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https://reference.globalspec.com/standard/3879629/iec-60027-3-2002-letter-symbols-to-be-used-in-electrical-technology-part-3-logarithmic-and-related-quantities-and-their-units
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IEC 60027-3:2002Letter symbols to be used in electrical technology - Part 3: Logarithmic and related quantities, and their units
published
Organization: IEC - International Electrotechnical Commission Publication Date: 19 July 2002 Status: published Page Count: 25 ICS Code (Character symbols): 01.075 ICS Code (Quantities and units): 01.060
Abstracts
abstract
Applies to logarithmic quantities and units. Quantities that can be expressed as the logarithm of a dimensionless quantity, such as the ratio of two physical quantities of the same kind, can be regarded and treated in different ways. In many cases, differences do not affect practical treatment.
Document History
IEC 60027-3:2002 - Letter symbols to be used in electrical technology - Part 3: Logarithmic and related quantities, and their units
July 19, 2002 - IEC - International Electrotechnical Commission
Applies to logarithmic quantities and units. Quantities that can be expressed as the logarithm of a dimensionless quantity, such as the ratio of two physical quantities of the same kind, can be regarded and treated in different ways. In many cases, differences do not affect practical treatment.
IEC 60027-3:1989/AMD1:2000 - Amendment 1 - Letter symbols to be used in electrical technology - Part 3: Logarithmic quantities and units
March 10, 2000 - IEC - International Electrotechnical Commission
A description is not available for this item.
IEC 60027-3:1989 - Letter symbols to be used in electrical technology - Part 3: Logarithmic quantities and units
December 15, 1989 - IEC - International Electrotechnical Commission
Applies to logarithmic quantities and units. Quantities that can be expressed as the logarithm of a dimensionless quantity, such as the ratio of two physical quantities of the same kind, can be regarded and treated in different ways. In many cases, differences do not affect practical treatment.
IEC 60027-3:1974 - Letter symbols to be used in electrical technology - Part 3: Logarithmic quantities and units
January 1, 1974 - IEC - International Electrotechnical Commission
A description is not available for this item.
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http://mathhelpforum.com/advanced-statistics/202260-probability-theory-expected-vales-exponential-distribution.html
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# Thread: probability theory-expected vales for exponential distribution
1. ## probability theory-expected vales for exponential distribution
Here's a problem that I got when I self-study probability theory with the course recorded at Harvard in stat 110.
A post office has 2 clerks. Alice enters the post office while 2 other customers,
Bob and Claire, are being served by the 2 clerks. She is next in line. Assume
that the time a clerk spends serving a customer has the Exponential(lambda) distribution.
(b) What is the expected total time that Alice needs to spend at the post
office?
the answer gives that the expected waiting time(waiting in line) is 1/(2lambda) and the expected time being served in 1/lambda, so the total time is 3/(2lambda)
I don't understand why the expected waiting time(waiting in line) is 1/(2lambda)
the solution says that the minimum of two independent
Exponentials is Exponential with rate parameter the sum of the two
individual rate parameters.
where does the rationale of the statement above come from.......
thanks..
2. ## Re: probability theory-expected vales for exponential distribution
Hey pyromania.
What you looking at comes from an area known as an order statistics. If you want to prove the result yourself calculate Min(A,B).
To start you off consider P[Min(A,B)] which is given by P(A > x and B > x) = P(C < x) = P(A > x)P(B > x) [independence] which is equal to [1 - P(A < x)][1 - P(B < x)] and P(A < x) is the CDF for A(x) and the P(B < x) is the CDF of B(x). Now differentiate both sides to get the PDF of C and compare the two.
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http://math.stackexchange.com/questions/173113/relationship-between-prime-factorizations-of-n-and-n1
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# Relationship between prime factorizations of $n$ and $n+1$?
Are there any theorems that give us any information about the prime factorization of some integer $n+1$, if we already know the factorization of $n$?
Recalling Euclid's famous proof for the infinity of the set of prime numbers, I guess we know that if $n = p_1 p_2 p_3$, then $n+1$ cannot have $p_1$, $p_2$, or $p_3$ as factors. But is there any way we could use the information about $n$'s factorization to determine something more precise about the factorization of $n+1$?
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Seems unlikely, given the extreme cases of Fermat and Mersenne primes. – user17794 Jul 20 '12 at 4:50
In general I think not (though the experts will confirm this), but if $n$ has two factors (not necessarily prime) which differ by 2 so that $n=r(r+2)$ then $n+1=(r+1)^2$. – Mark Bennet Jul 20 '12 at 4:53
$n$ and $n+1$ are relatively prime, so no prime factor of one can be a prime factor of the other. But beyond that, there is no regularity; if $n$ is prime and different from $2$, then $n+1$ is certainly not prime; and conversely for $n+1\neq 3$. There is no known regularity in the functions $\omega(n)$, $\Omega(n)$. – Arturo Magidin Jul 20 '12 at 5:18
Currently very little is known about this problem and it appears intractable by known methods, though it is of great interest. More generally, additive number theory takes upon the challenge of studying the additive structure of prime numbers, which is bound to be difficult due to their inherent multiplicative nature.
Some problems that would greatly benefit from knowing how addition effects prime factorizations include: The Twin Prime Conjecture and The Collatz Conjecture.
-
As I wrote when this question was raised at MathOverflow, if knowing the factorization of $n$ told you much about the factorization of $n+1$, the Fermat numbers $2^{2^n}+1$ would be easy --- but, they aren't.
-
While the factorisation of $N$ might not help much with the factorisation of $N+1$, in special circumstances, it can help with determining primality of $N$.
Famous examples of this include Pépin's Test for primality of numbers of the form $2^{2^n}+1$, and Proth's Theorem for primality of numbers of the form $k \times 2^n+1$ where $k<2^n$ (Proth primes feature on the top 20 known primes).
There are more general primality tests for $N+1$ based on (partial) knowledge of the factorisation of $N$, but they tend to be less elegant. For example, this was snipped from "Factorizations of $b^n \pm 1$, b = 2, 3, 5, 6, 7, 10, 11, 12 Up to High Powers" by Brillhart, Lehmer, Selfridge, Tuckerman, and Wagstaff, Jr.:
Theorem 11. Let $N-1=FR$, where $F$ is completely factored and $(F,R)=1$. Suppose there exists an $a$ for which $a^{N-1} \equiv 1 \pmod N$ and $(a^{(N-1)/q}-1,N)=1$ for each prime factor $q$ of $F$. Let $R=rF+s$, $1 \leq s < F$, and suppose $N<2F^3+2F$, $F>2$. If $r$ is odd, or if $r$ is even and $s^2-4r=t^2$, then $N$ is prime. Otherwise, $s^2-4r=t^2$ and $$N = [\frac{1}{2}(s-t)F+1][\frac{1}{2}(s+t)F+1].$$
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https://www.gradesaver.com/textbooks/math/algebra/introductory-algebra-for-college-students-7th-edition/chapter-5-section-5-5-dividing-polynomials-exercise-set-page-385/17
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## Introductory Algebra for College Students (7th Edition)
$100$
RECALL: The zero-exponent rule states that for any non-zero number $a$, $a^0=1$ Use the zero-exponent rule to obtain: $=100(1) \\=100$
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https://www.semanticscholar.org/paper/Calculations-with-off-shell-matrix-elements%2C-TMD-Bury-Hameren/a8dcf85d6a57a516ee47d1d64edcb45e4ef4897f
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# Calculations with off-shell matrix elements, TMD parton densities and TMD parton showers
@article{Bury2018CalculationsWO,
title={Calculations with off-shell matrix elements, TMD parton densities and TMD parton showers},
author={Marcin Bury and A. van Hameren and Hannes Jung and Krzysztof Kutak and Sebastian Sapeta and Mirko Serino},
journal={The European Physical Journal. C, Particles and Fields},
year={2018},
volume={78}
}
• M. Bury, +3 authors M. Serino
• Published 16 December 2017
• Physics, Medicine
• The European Physical Journal. C, Particles and Fields
A new calculation using off-shell matrix elements with TMD parton densities supplemented with a newly developed initial state TMD parton shower is described. The calculation is based on the KaTie package for an automated calculation of the partonic process in high-energy factorization, making use of TMD parton densities implemented in TMDlib. The partonic events are stored in an LHE file, similar to the conventional LHE files, but now containing the transverse momenta of the initial partons… Expand
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Matching NLO QCD and parton showers in heavy flavour production
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Production of two charm quark–antiquark pairs in single-parton scattering within the kt -factorization approach
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Collinear and TMD quark and gluon densities from parton branching solution of QCD evolution equations
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A bstractWe study parton-branching solutions of QCD evolution equations and present a method to construct both collinear and transverse momentum dependent (TMD) parton densities from this approach.Expand
Matching NLO QCD computations and parton shower simulations
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We propose a method for matching the next-to-leading order (NLO) calculation of a given QCD process with a parton shower Monte Carlo (MC) simulation. The method has the following features: fullyExpand
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https://ejde.math.txstate.edu/Volumes/2010/153/abstr.html
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Electron. J. Diff. Equ., Vol. 2010(2010), No. 153, pp. 1-7.
### Regularity for 3D Navier-Stokes equations in terms of two components of the vorticity Sadek Gala
Abstract:
We establish regularity conditions for the 3D Navier-Stokes equation via two components of the vorticity vector. It is known that if a Leray-Hopf weak solution satisfies
where form the two components of the vorticity, , then becomes the classical solution on (see [5]). We prove the regularity of Leray-Hopf weak solution under each of the following two (weaker) conditions:
where is the Morrey-Campanato space. Since is a proper subspace of , our regularity criterion improves the results in Chae-Choe [5].
Submitted May 20, 2010. Published October 28, 2010.
Math Subject Classifications: 35Q35, 76C99.
Key Words: Navier-Stokes equations; regularity conditions; Morrey-Campaanto spaces.
Show me the PDF file (219 KB), TEX file, and other files for this article.
Sadek Gala Department of Mathematics, University of Mostaganem Box 227, Mostaganem 27000, Algeria email: [email protected]
Return to the EJDE web page
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https://eepower.com/technical-articles/integrated-capacitors-reduce-commutation-loop-inductance/
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Technical Article
# Integrated Capacitors Reduce Commutation Loop Inductance
January 22, 2020 by Gyorgy Kovacs
## This article highlights Vincotech MLCC SMD capacitors with X7R dielectric that significantly reduced switching devices voltage overshoot during turn-OFF.
Designers pursuing the right balance of price and performance to satisfy today’s demand for power-switching applications are cutting it close with inverters. And engineers are more likely to select parts with performance parameters in the neighborhood of the target specifications to gain a built-in design advantage. This is why margins between devices’ maximum electrical value and the application parameters are shrinking.
Power modules are a big step forward for engineers seeking to boost efficiency. They have several advantages over discrete components, one being superior parasitic performance. Nonetheless, there is still room for improvement, particularly if we take the electric components connected to the power module into consideration. These connections are still the source of parasitic inductances that adversely affect switching performance. They may even jeopardize the switching elements if the design lacks the necessary voltage buffer.
Parasitic inductance in an inverter power bridge leads to inefficiencies. The voltage spikes during the power device’s switch-OFF cycle (Figure 1) at a high rate of dI/dt:
$\dpi{150}&space;V_{CE(peak)}&space;=&space;V_{CE}+L_{x}\times&space;\frac{di}{dt}$
##### Figure 1: Switch-OFF curves (Uce and Ic) of a power switch
Switching time may have to be increased to prevent voltage spikes from damaging power devices. Increasing power devices’ switching time would also increase turn-ON and turn-OFF losses in each power switch. This adds to the switching losses, generating even more heat to be dissipated in the switching devices.
DC link capacitors can mitigate the effects of inductance from the DC voltage source and reduce the switching component’s voltage overshoot. The key to good performance is a low-inductance design that connects these parts so as to minimize PCB and module pins’ stray inductance. Even so, the decrease in parasitic inductances is unremarkable no matter how carefully the designer configures this electric circuit. It certainly cannot compare installing a capacitor with a snubber function in the module (Figure 2). This integrated capacitor provides a low-inductive, high-frequency solution that closes the commutation loop.
##### Figure 2: Position of the snubber capacitor as it relates to the parasitic inductances of a module design
It is standard practice at Vincotech to integrate MLCC SMD capacitors. High voltage (650 -1000 V) parts in case size 1206 to 2220 can be applied as a snubber. Different types of capacitors may be used depending on the given specification. Devices with X7R (class2) dielectric materials have s higher capacitance in the same package as C0G/NP0 parts, but class 2 materials have a significant DC bias effect. This means that the part’s capacitance value is significantly decreased at the rated voltage (Figure 3).
##### Figure 3: K-Sim (www.kemet.com) simulation of X7R capacitor showing the DC bias dependency
The comparative measurements of the SiC MOSFET booster configuration shown in figure 4 were taken to illustrate the behavior of the different setups, including one without a snubber capacitor. This test used a standard double-pulse measurement system and the MOSFETs’ nominal current. The switching devices were encapsulated in a standard Vincotech package with the additional snubbers placed on the layout by design.
##### Figure 4: Booster configuration to test the integrated DC snubber effect
option value overshoot (absolute value) no capacitor - 205 (805 V) X7R 100 nF 150 (750 V) C0G 22 nF 121 (721 V)
##### Table 1: SMD capacitor effect on overshoot voltage
The integrated capacitors significantly reduced the switching devices’ voltage overshoot during turn-off. This test also underscored the differences between capacitors’ dielectric materials. C0G/NP0 devices have significantly lower capacitances than their X7R counterpart and exhibited even better performance. This is attributable to the X7R class 2 material’s high DC bias effect.
##### Figure 5: Switch-OFF waveforms of the DC snubber effect test circuit. Yellow = gate voltage; green = collector-emitter voltage; pink = collector current
C0G/NP0 capacitors’ dissipation factor (DF) parameters are superior to those of the X7R, which results in less self-heating because of the dissipation factor’s lower ESR (equivalent series resistance) component.
Another advantage of the C0G/NP0 material is that it is immune to the aging phenomenon that causes the capacitance and dissipation factor of X7R devices to decrease over time.
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http://tex.stackexchange.com/questions/9510/changing-side-of-line-numbering-in-two-columns-documents?answertab=votes
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# Changing side of line numbering in two columns documents
I'm trying to type some report and I have a small problem with the twocolums document class and the line numbering in listings.
The document is on two columns :
\documentclass[8pt,[...],a4paper,twocolumn]{article}
The listings can end up either on the left or the right column. The problem is: if I put
\lstset{numbers=left,frame=tb,[...]}
the space between the columns is not sufficient when the listing is on the right column and the text from the first column is written over.
Is there any way to ask the listings to put the line numbers "outside" ?
-
\documentclass[a4paper,twocolumn]{article}
\usepackage{listings}
\lstset{numbers=left,frame=tb,numbersep=1em,xleftmargin=2em,
basicstyle=\ttfamily\small}
\parindent=0pt
\begin{document}
\rule{\linewidth}{1pt}
\begin{lstlisting}
\def\showDiff#1#2{}%
\end{lstlisting}
\newpage
\rule{\linewidth}{1pt}
\begin{lstlisting}
\def\showDiff#1#2{}%
\end{lstlisting}
\end{document}
-
Could you explain what your code is doing? – Seamus Jan 23 '11 at 12:18
It produce two listings, one on each column, with the numbers on the left. But instead of increasing the space between the columns, it adds a margin for the numbers, so the listing is not as large as before without having narrower columns. Not quite the solution i was thinking about, but it produces a good result. – Thomas Schwery Jan 23 '11 at 17:24
Even though it doesn't exactly answer the question, it's the solution i'm using now ... – Thomas Schwery Jan 29 '11 at 21:53
Even if it were possible, for code listings I would find line numbers on the right hand side unclear and confusing. I suggest to increase the space between columns in your document:
\setlength{\columnsep}{25pt}
EDIT: Fixed embarassing typo in code sampling.
-
That's what i'm doing for now, but i would like to know if there was a way to change automatically the side of the numbering depending on the column the listing is in. – Thomas Schwery Jan 23 '11 at 13:00
the numbers are always on the left. See my example for setting it correct. – Herbert Jan 23 '11 at 15:02
You can try this:
\documentclass[a4paper,twocolumn]{article}
\usepackage[switch]{lineno}
\begin{document}
\linenumbers
\end{document}
-
But that only gives you line numbering, one of many features of the listings package. – Chris H Jan 30 '14 at 13:07
|
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https://greenleafngo.org/renewable-energy/
|
Renewable Energy
Green Leaf, with its qualified and professionals team of volunteers, will identify those areas where possibilities of renewable energy could be implemented at various stages. Green Leaf Trust welcomes grass root innovators like root top solar and rain water harvesting of renewable energy and their R&D, startups, technologies and helps them to build a sustainable future.
Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. Renewable energy often provides energy in four important areas: electricity generation, air and water heating/cooling, transportation, and rural (off-grid) energy services. Renewable energy resources exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency is resulting in significant energy security, climate change mitigation, and economic benefits. In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power. At the national level, at least 30 nations around the world already have renewable energy contributing more than 20 percent of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond.
The government of India, through the Ministry of New and Renewable Energy (MNRE) has been activity involved in implementing various schemes for power generation through renewable sources like solar, wind, hydro and waste to power.
|
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http://mathoverflow.net/revisions/50005/list
|
MathOverflow will be down for maintenance for approximately 3 hours, starting Monday evening (06/24/2013) at approximately 9:00 PM Eastern time (UTC-4).
Update. Here is an explicit example (which also preserves the $\mathbb Q$-span of the basis). Let $V=\ell_2$ over $\mathbb R$ and $(e_j)$ the standard basis. Define $T:V\to V$ by$$(Tx)_1 &= x_1+3x_2+x_3 \\ (Tx)_2 &= 3x_1+10x_2+6x_3+x_4 \\ (Tx)_n &= x_{n-2}+6x_{n-1}+11x_n+6x_{n+1}+x_{n+2}, \qquad n>2 .$$Let $\alpha$ be the root of $p(x)=x^2+3x+1$ such that $|\alpha|<1$. Then the vector $v\in\ell_2$ defined by $v_n=\alpha^n$ satisfies $Tv=0$, so it is an eigenvector for $\lambda=0$. On the other hand, no nonzero rational vector $w$ satisfies $Tw=0$ because the relation $Tw=0$ implies the recurrence relation w_{n+4}=-6w_{n+3}-11w_{n+2}-6w_{n+1}-w_n ,which does not have rational solutions tending to 0.
2 minor clarification
Let $V=\ell_2$ over $\mathbb R$ and $(e_j)$ the standard basis, so that $\langle x,e_j\rangle=x_j$ for every $x\in\ell_2$. Let $v\in V$ be a unit vector with irrational ratios of coordinates (for definiteness, take a geometric progression like $(c\pi^{-n})_{n\in\mathbb N}$). Then there exist a continuous self-adjoint $T:V\to V$ with rational coordinates such that $\ker T=\langle v\rangle$. So we have $\lambda=0$ but no $\lambda$-eigenvector is rational.
I represent $T$ by its (infinite) matrix $(t_{ij})_{i,j\in\mathbb N}$, $t_{ij}=\langle Te_i,e_j\rangle$. This matrix should be symmetric, and continuity of the resulting operator should be taken care of.
Begin with a self-adjoint $A$ such that $\ker A=\langle v\rangle$ with irrational components $a_{ij}$. For example, let $A$ be the projection to the orthogonal complement of $v$, so $a_{ij}=\delta_{ij}-v_iv_j$. I am going to approximate the matrix $(a_{ij})$ by a rational matrix $(t_{ij})$ such that the kernel stays the same.
Since $Av=0$, each row of our matrix is orthogonal to $v$. Approximate the first row $a_i=(a_{1i})$ by a rational vector $t_1=(t_{1i})$ such that $\langle t_1,v\rangle=0$ and $|t_{1i}-a_{1i}|$ is bounded by a rapidly decaying geometric progression (see below for details). Replace the first row and the first column of the matrix by this approximation. Then adjust the diagonal elements $a_{ii}$ so that the rows remain orthogonal to $v$, namely change $a_{ii}$ to $a_{ii}-(a_{1i}-t_{1i})v_1v_i^{-1}$. Recall that $v_i$ is a not-so-fast decaying geometric progression, so this adjustment is a small change.
Now remove the first row and the first column from the matrix, and the first component from $v$. Apply the same procedure to the truncated data: namely approximate the first remaining row and the first remaining column by a rational vector whose scalar product with $v$ is the same as before, then adjust the diagonal elements so that the scalar products of all rows with $v$ are preserved. Repeat ad infinitum. Note that every element of the original matrix is changed only finitely many times, and $v$ belongs to the kernel of the matrix after each step.
The approximations are controlled and the adjustments are bounded in terms of approximations, so the sum $\sum (a_{ij}-t_{ij})^2$ can be made arbitrarily small. This implies that $T$ is continuous and $\|T-A\|$ is small (say, less than 1/2), so we have $Tv=0$ and $\|Tw\|\ge\frac12\|w\|$ for all $w$ orthogonal to $w$. Therefore $\ker T=\langle v\rangle$. However $v$ cannot be rescaled to a rational vector.
It remains to show that every vector $w\in\ell_2$ can be approximated by a rational vector $w'$ such that $\langle w',v\rangle=\langle w,v\rangle$ and $w'_i-w_i$ is bounded by a small, fast decaying progression. Let $w'_1=w_1+\varepsilon_1$ be a rational approximation of $w_1$, then let $w'_2=w_2-\varepsilon_1v_1v_2^{-1}+\varepsilon_2$ be a rational approximation of $w_2-\varepsilon_1v_1v_2^{-1}$, then let $w'_3=w_3-\varepsilon_2v_2v_3^{-1}+\varepsilon_3$ be a rational approximation of $w_3-\varepsilon_2v_2v_3^{-1}$, and so on. The $\varepsilon_i$ at each step can be chosen arbitrarily small, and the resulting vector $w'$ satisfies $\langle w'-w,v\rangle=0$.
1
Let $V=\ell_2$ over $\mathbb R$ and $(e_j)$ the standard basis, so that $\langle x,e_j\rangle=x_j$ for every $x\in\ell_2$. Let $v\in V$ be a unit vector with irrational ratios of coordinates (for definiteness, take a geometric progression like $(c\pi^{-n})_{n\in\mathbb N}$). Then there exist a continuous self-adjoint $T:V\to V$ with rational coordinates such that $\ker T=\langle v\rangle$.
I represent $T$ by its (infinite) matrix $(t_{ij})_{i,j\in\mathbb N}$, $t_{ij}=\langle Te_i,e_j\rangle$. This matrix should be symmetric, and continuity of the resulting operator should be taken care of.
Begin with a self-adjoint $A$ such that $\ker A=\langle v\rangle$ with irrational components $a_{ij}$. For example, let $A$ be the projection to the orthogonal complement of $v$, so $a_{ij}=\delta_{ij}-v_iv_j$. I am going to approximate the matrix $(a_{ij})$ by a rational matrix $(t_{ij})$ such that the kernel stays the same.
Since $Av=0$, each row of our matrix is orthogonal to $v$. Approximate the first row $a_i=(a_{1i})$ by a rational vector $t_1=(t_{1i})$ such that $\langle t_1,v\rangle=0$ and $|t_{1i}-a_{1i}|$ is bounded by a rapidly decaying geometric progression (see below for details). Replace the first row and the first column of the matrix by this approximation. Then adjust the diagonal elements $a_{ii}$ so that the rows remain orthogonal to $v$, namely change $a_{ii}$ to $a_{ii}-(a_{1i}-t_{1i})v_1v_i^{-1}$. Recall that $v_i$ is a not-so-fast decaying geometric progression, so this adjustment is a small change.
Now remove the first row and the first column from the matrix, and the first component from $v$. Apply the same procedure to the truncated data: namely approximate the first remaining row and the first remaining column by a rational vector whose scalar product with $v$ is the same as before, then adjust the diagonal elements so that the scalar products of all rows with $v$ are preserved. Repeat ad infinitum. Note that every element of the original matrix is changed only finitely many times, and $v$ belongs to the kernel of the matrix after each step.
The approximations are controlled and the adjustments are bounded in terms of approximations, so the sum $\sum (a_{ij}-t_{ij})^2$ can be made arbitrarily small. This implies that $T$ is continuous and $\|T-A\|$ is small (say, less than 1/2), so we have $Tv=0$ and $\|Tw\|\ge\frac12\|w\|$ for all $w$ orthogonal to $w$. Therefore $\ker T=\langle v\rangle$. However $v$ cannot be rescaled to a rational vector.
It remains to show that every vector $w\in\ell_2$ can be approximated by a rational vector $w'$ such that $\langle w',v\rangle=\langle w,v\rangle$ and $w'_i-w_i$ is bounded by a small, fast decaying progression. Let $w'_1=w_1+\varepsilon_1$ be a rational approximation of $w_1$, then let $w'_2=w_2-\varepsilon_1v_1v_2^{-1}+\varepsilon_2$ be a rational approximation of $w_2-\varepsilon_1v_1v_2^{-1}$, then let $w'_3=w_3-\varepsilon_2v_2v_3^{-1}+\varepsilon_3$ be a rational approximation of $w_3-\varepsilon_2v_2v_3^{-1}$, and so on. The $\varepsilon_i$ at each step can be chosen arbitrarily small, and the resulting vector $w'$ satisfies $\langle w'-w,v\rangle=0$.
|
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|
https://methodelafaypdf.fr/carbonsteel/earthing-strip-steels-2475.html
|
earthing strip steels- CBD Steel
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# earthing strip steels
As the world's leading steel supplier, we can provide a wide range of steel types, including carbon steel, weathering steel, boiler steel, structural steel, etc., and we can meet customers' requirements in any size, as well as the production of steel and complete plant plans. If you are interested in these aspects, please contact us.
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### Manufacturer of GI Angle & GI Strip by Shri Laxmi Steels , earthing strip steels
Incepted in the year of 2004, Shri Lakshmi Steels is leading Manufacturer of GI Angle, GI Strip, GI Pipe, Slotted Angle etc. We design and develop our entire range of products using superior quality basic material and modern technology to ensure that final output satisfies with Earthing Products - GI Flat Earthing Strip Manufacturer , earthing strip steelsManufacturer of Earthing Products - GI Flat Earthing Strip, GI Earthing Strip, Earthing Wire and GI Earthing Rod offered by Rajnish Steels, Sonipat, Haryana.GI EARTHING - GI Earthing Strip Manufacturer from MumbaiGI earth strip is connected to the actual earthing bar than it is ok to insulate with what ever means. In some places GI coated steel cables are used instead of insulated cables due to cost or deter thefts.
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### Hard Facts About Bonding to Steel EC&M - Home EC&M
Do you know the special grounding requirements involved in bonding to steel? When you think of grounding, you may visualize ground grid conductors, electrodes, interconnections -- all buried in the soil. But, many of the currents these components must carry and dissipate enter the below grade ground system from an above grade structural member. Bonding the ground conductor to the building , earthing strip steelsBRITISH STANDARD BS 7430:1998Table 11 Earth fault currents for copper strip earthing conductors 27 Table 12 Earth fault currents for aluminium strip earthing conductors 28 , earthing strip steels structural steels Technical delivery conditions. 3 Definitions For the purposes of this British Standard, the definitions given Coated Steel Coils Manufacturer,Aluminized Steel Coils , earthing strip steelsGI Earthing Strips Use our GI Earthing Strips which are easy to install, have accurate width, thickness and finish, etc. They are used to give protection against static electricity and display great thermal, flexibility and electrical conductivity and robustness.
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Gi Strip is a series of connections into the ground for electrical safety. The earthing terminal is the main component in the system. Putting it in a simple layman''s language, earthing terminal is connected to anyAluminized Steel coil,Galvanized steel,Electro Galvanized , earthing strip steelsEstablished in the year of 1987, we "J. K. Steel Corporation" are an acclaimed name in the business preoccupied in manufacturing, exporting and supplying a comprehensive catalogue of Industrial Steel Products. In our product series, we are providing maximum quality Hot Dip Galvanize Steel, Cold Rolled Steel - CRCA and Stainless Steel Strips.These products are fabricated from best quality , earthing strip steelsElectro Strip Steel Suppliers, Manufacturer, Distributor , earthing strip steels offers 194 Electro Strip Steel Suppliers, and Electro Strip Steel Manufacturers, Distributors, Factories, Companies. There are 84 OEM, 65 ODM, 15 Self Patent. Find high quality Electro Strip Steel Suppliers on .
### Code of practice for protective earthing of electrical , earthing strip steels
Table 6 Earth fault currents (in kA) for copper strip earthing conductors 52 Table 7 Earth fault currents (in kA) for aluminium strip earthing conductors 53 Table8 Values of K and 53 , earthing strip steels Stainless steels List of stainless steels BS EN 10263-4:2001, Steel rod, bars and wire for cold heading and cold , earthing strip steelsThe Characteristics of Austenitic Stainless SteelStainless steels with a low nickel and high nitrogen content are classified as 200 series. Because it is a gas, however, only limited amounts of nitrogen can be added before deleterious effects arise, including the formation of nitrides and gas porosity that weaken the alloy.NGK Berylco Beryllium Copper Strip ProductsBeryllium Copper Strip Products from NGK Berylco feature High Strength & Elastic Modulus, High Fatigue Strength, Elevated Temperature Properties and Resistance to Stress Relaxation, Good Formability, High Electrical Conductivity, Corrosion Resistance, and Reliability. Beryllium copper alloys have high mechanical strength and a favorable elastic modulus, which makes them highly suitable as
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### How to Demagnetize Steel Sciencing
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### Hot-dip galvanized steel strip from thyssenkrupp
Hot-dip galvanized steel strip from thyssenkrupp combines the advantages of batch and continuous galvanizing. The hot-rolled steel is zinc-coated continuously and unlike conventionally hot-dip galvanized slit strip its edges are also coated. Hot-rolled steels to DIN EN 10111 and 10025-2 are available as substrate materials.Steel NewsThe product portfolio includes deep-drawing and grain-oriented (GO) steels, but also galvanized earthing strip and wire. After its merger with Nová Hu Válcovna za studena, the portfolio was expanded by carbon and micro-alloyed steels and steel binding strip. A major part of the companys GO steel production is exported, notably to , earthing strip steelsHot-dip galvanized steel strip from thyssenkruppHot-dip galvanized steel strip from thyssenkrupp combines the advantages of batch and continuous galvanizing. The hot-rolled steel is zinc-coated continuously and unlike conventionally hot-dip galvanized slit strip its edges are also coated. Hot-rolled steels to DIN EN 10111 and 10025-2 are available as substrate materials.
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### Guide Earthing systems - OBO Bettermann
2 Earthing fixed point 3 Earth entry rod 4 Cross-connector 5 Cross-connector with corrosion protection 6 Corrosion protection strip 7 Flat conductor 8 Connection terminal for reinforced steels Note Connections in the earth must be protected with a corrosion protection strip. WELDING OF STAINLESS STEELS AND OTHER JOINING By definition, stainless steels are iron-base alloys containing 10% or more chromium, which imparts to the metal the corrosion-resistant properties for which stainless steels are so highly regarded. The chromium content may be increased and other alloying elements added or adjusted to meet specific end-use or manufacturing requirements.Motwane. Clamp on MethodSimply clamp around the conductor or earthing strip and measure the earth resistance fast and accurately. The unique long jaw is particularly suitable where grounding is done by flat steels or copper strips. It has low battery indication & data hold facility with in built memory storage of upto 99 test results. DECT-3 has got the double , earthing strip steels
### BS 7430(1998) 1998 CODE OF PRACTICE FOR EARTHING
11 Earth fault currents for copper strip earthing conductors 12 Earth fault currents for aluminium strip earthing conductors 13 Values of K and SS , earthing strip steels HOT ROLLED PRODUCTS OF NON-ALLOY STRUCTURAL STEELS TECHNICAL DELIVERY CONDITIONS BS EN 60898 1991 :SINGAPORE STANDARD Code of practice for earthing10 Earth fault currents (in kA) for copper strip earthing conductors 37 11 Earth fault currents (in kA) for aluminium strip earthing conductors 38 12 Values of K and 38 13 Values of current densities for earthing conductors 58 , earthing strip steels BS EN 10025-1 Hot rolled products of structural steels. General technical delivery conditions BS EN 1011-4 , earthing strip steels#TITLE# |KOBELCO - KOBE STEEL, LTD.The ABCs of Arc Welding Band-Overlaying What Overlaying with Strip Electrode Offers. The overlaying with a strip electrode, so-called Band-Overlaying, features the use of thin, wide strip electrodes in combination with fluxes instead of wire electrodes for submerged arc welding (SAW) and electroslag welding (ESW) as illustrated in Figure 1.
### Technical Specifications for Earth Rods/Accessories , earthing strip steels
AS/NZS 1442 Carbon steels and carbon-manganese steels - Hot-rolled bars and semifinished products . Technical Specification for Earth Rods/ Accessories, Connectors and Earth Enhancing , earthing strip steels various components of the earthing system including the earth rod, Understanding Electric Arc Furnace Steel Making OperationsDissolved gases, especially hydrogen (H2) and nitrogen (N2), is a concern for steel makers. Burying of the arc also helps to prevent N2 from being exposed to the arc where it can dissociate and enter into the steel. If the CO is evolved within the steel bath, it helps to strip N2 and H2 from the steel.Gi Earthing PLates Manufacturer - Gi Earthing Plates , earthing strip steelsGi Earthing PLates Manufacturer Being a quality conscious company, we are engaged in manufacturing a range of earthing materials, that are made by our dexterous engineers who always strive to satisfy the customers. Our entire range includes GI earthing strips, GI earthing plates, GI earthing wires, gi earthing pipes, earthing powder and others.
### DIN EN 10151 - Stainless steel strip for springs , earthing strip steels
This European Standard applies to cold rolled narrow strip of thicknesses up to and including 3 mm in rolled widths less than 600 mm made from the stainless steel grades listed in Table 1. The steels are used in the conditions given in Table 4 for the production of springs and spring parts that are exposed to corrosive effects and sometimes , earthing strip steelsEarthing Material In Howrah, Earthing Material Dealers , earthing strip steelsFind the top earthing material dealers, traders, distributors, wholesalers, manufacturers & suppliers in Howrah, West Bengal. Get latest & updated earthing material Cold Rolled Grain Oriented (CRGO) Silicon Steel , earthing strip steelsJan 02, 2019 · N. P. Goss, the early inventor of the cold rolled grain oriented silicon steel or CRGO steel manufacturing process in 1933 gave the idea in his own words I have experimental evidence which leads me to believe that there is an apparent relation between the grain size and ductility of a specimen and its magnetic properties.
### Properties and Composition of Type 201 Stainless Steel
Type 201 is part of the 200 series of austenitic stainless steel. Originally developed to conserve nickel, this family of stainless steels is characterized by low nickel content. Type 201 can substitute for type 301 in many applications, but it's less resistant to corrosion Copper Strips Manufacturers, Suppliers, Exporters,Dealers , earthing strip steelsCopper Earthing, Copper Strips, Copper Control Panels, Copper Foils, Aluminium Bus-Bars. Send Enquiry Porwal Metallicanarrow metal steel strip, narrow metal steel strip , earthing strip steelsZ100 Hot Dipped Zinc Galvanized Narrow Metal Steel Strip Material SGCC,SGCH,G350,G450,G550,DX51D,DX52D,DX53D Hardness S oft (HRB 60),medium hard(HRB60-85),Full hard(HRB85- 95) Surface treatment Chromated/Non-Chromated, Oiled/Non-oiled, Skin pass 20' container weight 25-28tons (unless there is limited weight at destination port) Logo Printed according
### Cressall
Cressall neutral earthing resistors (NERs) are employed in AC distribution networks , earthing strip steels stainless steel strip, wound edgewise into oval coils. Each coil is supported by ridged , earthing strip steels stainless steels capable of withstanding temperature excursions to 1100°C whilst retaining Vinyl Coated - Cable & Wire Rope / Pulling , earthing strip steelsMuzata Stainless Steel 304 Black Wire Rope,Vinyl Coated,7x7 Strand Core,Wire Rope OD 1/16",Coated OD 3/32",165ft,Railing Kit Decking Stair,Light Guide Wire,7x7 Strand,358lbs Breaking Strengthelectrical resistance - Why is stainless steel a poor , earthing strip steelsYou are correct, stainless steel is a really poor conductor compared to most metals. This source lists it as $7.496 \times 10^{-7}\ \mathrm{\Omega \cdot m}$ which is more than 40 times worse than copper.. The reason is that conductivity in metals is high is that metals form a crystal lattice where the outer shell electrons are shared and easily move through the lattice.
### Parmar Industries, Pune - Manufacturer of Cable Tray and , earthing strip steels
Parmar Industries is known to be amongst the prominent manufacturer of this highly commendable range of Earthing and Cable Tray. The offered range made up of the Cable Tray, Metal Grating, Earthing Material and many more. Offered products are designed using only high quality material in full compliance with the set industry parameters.FRP Roofing Sheet - FRP Sheet Wholesale Distributor from , earthing strip steelsWith the in depth experience, we are engaged in distributing and supplying of Pipe fitting, PVC pipes and fittings, G.I. pipes and fittings, Stainless steel pipes and fittings, Hardware tools, M.S. pipes, pipe threads and fittings and ropes.In addition to these, we also have in stock Industrial filters, Belts and rubber products, Brass valves and fittings, Water meter, FRP roofing sheet and , earthing strip steelsWhat forms of corrosion can occur in stainless steels?What forms of corrosion can occur in stainless steels? The most common forms of corrosion in stainless steel are Pitting corrosion - The passive layer on stainless steel can be attacked by certain chemical species. The chloride ion Cl- is the most common of these and is found in everyday materials such as salt and bleach. Pitting corrosion is , earthing strip steels
### Alloy Steel - Manganese Steel Casting Manufacturer from Pune
Manufacturer of Alloy Steel - Manganese Steel Casting, EN24 AISI:4340 817M40 34CrNiMo6 40NiCr4Mo3 Bright Steel Bar, M.S. Profile Cutting offered by Poly Metal India, Pune, Maharashtra.Corrosion damage in earth-termination systems - EE PublishersStainless steels should contain at least 18% chromium, 9% nickel and 2% molybdenum. Extensive testing has shown that only high-alloy stainless steel, e.g. material no. 1.4571, is sufficiently corrosion-resistant in the ground. Stainless steels without molybdenum are not suitable as earth electrode materials and not permitted by the standard.Spring Steel Strip, Packing Steel Strap, Corrugated Roof SheetSpring Steel Strip We are the leader in spring steel industry , and we can offer a wide variety of spring steel products to meet your specifications. Spring steel refers to steel, normally of the high carbon or alloy type, used in the manufacture of springs.
### RS Components, Ltd. Sealing Glands Data Sheets , earthing strip steels
Find RS Components, Ltd. Sealing Glands Data Sheets on GlobalSpec.Hydrochloric Acid Handbook - Occidental Petroleumcarbon, alloy and stainless steels. Steel pickling is the process by which iron oxides and scale are removed from the surface of steel by converting the oxides to soluble compounds. Pickling is required for steel products that undergo further processing such as wire production, coating of sheet and strip
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http://commons.apache.org/proper/commons-math/apidocs/org/apache/commons/math3/analysis/solvers/BracketedUnivariateSolver.html
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org.apache.commons.math3.analysis.solvers
## Interface BracketedUnivariateSolver<FUNC extends UnivariateFunction>
• Type Parameters:
FUNC - Type of function to solve.
All Superinterfaces:
BaseUnivariateSolver<FUNC>
All Known Implementing Classes:
BaseSecantSolver, BracketingNthOrderBrentSolver, IllinoisSolver, PegasusSolver, RegulaFalsiSolver
public interface BracketedUnivariateSolver<FUNC extends UnivariateFunction>
extends BaseUnivariateSolver<FUNC>
Interface for (univariate real) root-finding algorithms that maintain a bracketed solution. There are several advantages to having such root-finding algorithms:
• The bracketed solution guarantees that the root is kept within the interval. As such, these algorithms generally also guarantee convergence.
• The bracketed solution means that we have the opportunity to only return roots that are greater than or equal to the actual root, or are less than or equal to the actual root. That is, we can control whether under-approximations and over-approximations are allowed solutions. Other root-finding algorithms can usually only guarantee that the solution (the root that was found) is around the actual root.
For backwards compatibility, all root-finding algorithms must have ANY_SIDE as default for the allowed solutions.
Since:
3.0
Version:
$Id: BracketedUnivariateSolver.java 1364387 2012-07-22 18:14:11Z tn$
AllowedSolution
• ### Method Summary
Methods
Modifier and Type Method and Description
double solve(int maxEval, FUNC f, double min, double max, AllowedSolution allowedSolution)
Solve for a zero in the given interval.
double solve(int maxEval, FUNC f, double min, double max, double startValue, AllowedSolution allowedSolution)
Solve for a zero in the given interval, start at startValue.
• ### Methods inherited from interface org.apache.commons.math3.analysis.solvers.BaseUnivariateSolver
getAbsoluteAccuracy, getEvaluations, getFunctionValueAccuracy, getMaxEvaluations, getRelativeAccuracy, solve, solve, solve
• ### Method Detail
• #### solve
double solve(int maxEval,
FUNC f,
double min,
double max,
AllowedSolution allowedSolution)
Solve for a zero in the given interval. A solver may require that the interval brackets a single zero root. Solvers that do require bracketing should be able to handle the case where one of the endpoints is itself a root.
Parameters:
maxEval - Maximum number of evaluations.
f - Function to solve.
min - Lower bound for the interval.
max - Upper bound for the interval.
allowedSolution - The kind of solutions that the root-finding algorithm may accept as solutions.
Returns:
A value where the function is zero.
Throws:
MathIllegalArgumentException - if the arguments do not satisfy the requirements specified by the solver.
TooManyEvaluationsException - if the allowed number of evaluations is exceeded.
• #### solve
double solve(int maxEval,
FUNC f,
double min,
double max,
double startValue,
AllowedSolution allowedSolution)
Solve for a zero in the given interval, start at startValue. A solver may require that the interval brackets a single zero root. Solvers that do require bracketing should be able to handle the case where one of the endpoints is itself a root.
Parameters:
maxEval - Maximum number of evaluations.
f - Function to solve.
min - Lower bound for the interval.
max - Upper bound for the interval.
startValue - Start value to use.
allowedSolution - The kind of solutions that the root-finding algorithm may accept as solutions.
Returns:
A value where the function is zero.
Throws:
MathIllegalArgumentException - if the arguments do not satisfy the requirements specified by the solver.
TooManyEvaluationsException - if the allowed number of evaluations is exceeded.
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https://www.shaalaa.com/concept-notes/determinants-matrix-order-one-two_2334
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# Determinants of Matrix of Order One and Two
#### notes
Determinant of a matrix of order one:
Let A = [a] be the matrix of order 1, then determinant of A is defined to be equal to a
Determinant of a matrix of order two:
Let A =[(a_11,a_12),(a_21,a_22)] be a matrix of order 2 xx 2,
then the determinant of A is defined as:
det (A) = |A| = ∆ = |(a_11,a_12),(a_21,a_22)| = a_11a_22 - a_21a_12
If you would like to contribute notes or other learning material, please submit them using the button below.
### Shaalaa.com
Determinants part 2 (Matrix Order 1 ,2, 3) [00:13:22]
S
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https://www.science.gov/topicpages/p/photon+production+cross.html
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#### Sample records for photon production cross
1. XCOM: Photon Cross Sections Database
National Institute of Standards and Technology Data Gateway
SRD 8 XCOM: Photon Cross Sections Database (Web, free access) A web database is provided which can be used to calculate photon cross sections for scattering, photoelectric absorption and pair production, as well as total attenuation coefficients, for any element, compound or mixture (Z <= 100) at energies from 1 keV to 100 GeV.
2. Di-photon and photon + b/c production cross sections at Ecm = 1.96- TeV
SciTech Connect
Gajjar, Anant; /Liverpool U.
2005-05-01
Measurements of the di-photon cross section have been made in the central region and are found to be in good agreement with NLO QCD predictions. The cross section of events containing a photon and additional heavy flavor jet have also been measured, as well as the ratio of photon + b to photon + c. The statistically limited sample shows good agreement with Leading Order predictions.
3. Measurement of the inclusive isolated prompt photon production cross section at the Tevatron using the CDF detector
SciTech Connect
Deluca Silberberg, Carolina
2009-04-01
In this thesis we present the measurement of the inclusive isolated prompt photon cross section with a total integrated luminosity of 2.5 fb-1 of data collected with the CDF Run II detector at the Fermilab Tevatron Collider. The prompt photon cross section is a classic measurement to test perturbative QCD (pQCD) with potential to provide information on the parton distribution function (PDF), and sensitive to the presence of new physics at large photon transverse momentum. Prompt photons also constitute an irreducible background for important searches such as H → γγ, or SUSY and extra-dimensions with energetic photons in the final state. The Tevatron at Fermilab (Batavia, U.S.A.) is currently the hadron collider that operates at the highest energies in the world. It collides protons and antiprotons with a center-of-mass energy of 1.96 TeV. The CDF and the D0 experiments are located in two of its four interaction regions. In Run I at the Tevatron, the direct photon production cross section was measured by both CDF and DO, and first results in Run II have been presented by the DO Collaboration based on 380 pb-1. Both Run I and Run II results show agreement with the theoretical predictions except for the low pTγ region, where the observed and predicted shapes are different. Prompt photon production has been also extensively measured at fixed-target experiments in lower pTγ ranges, showing excess of data compared to the theory, particularly at high xT. From an experimental point of view, the study of the direct photon production has several advantages compared to QCD studies using jets. Electromagnetic calorimeters have better energy resolution than hadronic calorimeters, and the systematic uncertainty on the photon absolute energy scale is smaller. Furthermore, the determination of the photon kinematics does not require the use of jet algorithms. However, the measurements using photons
4. Measurement of the Differential Cross Section for Isolated Prompt Photon Production in pp Collisions at 7 TeV
SciTech Connect
Chatrchyan, S.; et al.,
2011-09-01
A measurement of the differential cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 36 inverse picobarns recorded by the CMS detector at the LHC. The measurement covers the pseudorapidity range |eta|<2.5 and the transverse energy range 25 < ET < 400 GeV, corresponding to the kinematic region 0.007 < xT < 0.114. Photon candidates are identified with two complementary methods, one based on photon conversions in the silicon tracker and the other on isolated energy deposits in the electromagnetic calorimeter. The measured cross section is presented as a function of ET in four pseudorapidity regions. The next-to-leading-order perturbative QCD calculations are consistent with the measured cross section.
5. Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at sqrt(s) = 7 TeV
SciTech Connect
Khachatryan, Vardan; et al.
2011-02-01
The differential cross section for the inclusive production of isolated prompt photons has been measured as a function of the photon transverse energy E_T-gamma in pp collisions at sqrt(s)=7 TeV using data recorded by the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.9 inverse picobarns. Photons are required to have a pseudorapidity |eta_gamma|<1.45 and E_T-gamma > 21 GeV, covering the kinematic region 0.006 < x_T < 0.086. The measured cross section is found to be in agreement with next-to-leading-order perturbative QCD calculations.
6. Measurements of the Differential Cross Sections for the Inclusive Production of a Photon and Heavy Flavor Jet
SciTech Connect
Duggan, Daniel
2009-04-01
This thesis presents the first measurement of the differential production cross section of a heavy flavor (bottom or charm) jet and direct photon at the Fermilab Tevatron. These measurements were performed using data recorded with the D0 detector from proton-antiproton collisions at a center of mass energy of √s = 1.96 TeV. These results probe a kinematic range for the photon transverse momentum of 30 < pTγ < 150 GeV and rapidity of |yγ| < 1.0 and for jet transverse momentum pTjet > 15 GeV and rapidity of |yjet| < 0.8. These results are compared to next-to-leading-order theoretical calculations.
7. Photon-initiated production of a dilepton final state at the LHC: Cross section versus forward-backward asymmetry studies
Accomando, Elena; Fiaschi, Juri; Hautmann, Francesco; Moretti, Stefano; Shepherd-Themistocleous, Claire H.
2017-02-01
We explore the effects of photon induced (PI) production of a dilepton final state in the Large Hadron Collider environment. Using QED parton distribution function (PDF) sets we can treat the photons as real partons inside the protons and compare their yield directly to that of the Drell-Yan (DY) process. In particular, we concentrate on an error analysis of the two mechanisms. In order to do so, we use the neural network parton distribution functions (NNPDF) set, which comes with a set of replicas to estimate the systematic PDF error, and the CT14 set. On the one hand, we find that the PI contribution becomes dominant over DY above a dilepton invariant mass of 3 TeV. On the other hand, the PI predictions are affected by a large uncertainty coming from the QED PDFs, well above the one affecting the DY mode. We assess the impact of these uncertainties in the context of resonant and nonresonant searches for a neutral massive vector boson (Z') through the differential cross section and forward-backward asymmetry (AFB) observables as a function of the dilepton invariant mass. While the former is subject to the aforementioned significant residual errors the latter shows the systematic error cancellation expected (recall that AFB is a ratio of cross sections) even in presence of PI contributions, so that the recently emphasized key role played by AFB as a valid tool for both Z' discovery and interpretation in both resonant and nonresonant mode is further consolidated.
8. Measurement of Production Cross Section Times Branching Ratio for W Boson + Photon and Z Boson + Photon and Search for Anomalous W Boson-Photon and Z Boson-Photon Couplings at 1.8 Tev
Vondracek, Mark Frank
Measurements of the production cross section times branching ratio for W + gamma and Z + gamma processes, where the W decays into a muon and neutrino and the Z decays into a muon pair, have been made from the analysis of 18.6 +/- 0.7 pb^{-1} of high-P_{T} muon data from proton-antiproton (pp) collisions. The data were collected with the Collider Detector at Fermilab (CDF) during the 1992-93 run. In a search for central photons (|eta| < 1.1) with transverse energy above 7 GeV and angular separation from the muon by at least Delta R = 0.7 we find 7 Wgamma and 4 Z gamma candidates. This translates into cross section times branching ratios of 9.0 +/- 6.4 pb for the Wgamma process and 6.6 +/- 3.4 pb for the Z gamma process. Separate measurements were made for photon E_{T} values above 11 GeV and 15 GeV. The cross section times branching ratio results were used to calculate a series of cross section ratios. An analysis designed to search for anomalous couplings between the gauge bosons was also carried out using these results. Assuming only one anomalous coupling to be non-zero at a time, the 95% CL limits on Wgamma anomalous couplings are, -3.7 < Deltakappa < 3.7, -1.2 < lambda < 1.2, -3.8 < ~kappa < 3.8 and -1.2 < ~lambda < 1.2. For ZZgamma anomalous couplings the experimental limits are measured to be, at the 95% CL, -4.6 < h_sp{30}{Z}(h _sp{10}{Z}) < 4.6 and -1.1 < h_sp{40}{Z}(h _sp{20}{Z}) < 1.1. For Zgammagamma anomalous couplings the experimental limits are measured to be, at, the 95% CL, -4.9 < h_sp{30}{gamma }(h_sp{10}{gamma}) < 4.9 and -1.2 < h_sp{40} {gamma}(h_sp{20}{ gamma}) < 1.2. Limits are placed on electromagnetic multipole moments for both the W and Z bosons using the measured limits of the anomalous couplings, and are presented in this thesis. All of the measurements presented in this thesis are consistent with Standard Model expectations.
9. Measurement of the isolated prompt photon production cross section in pp collisions at √s=7 TeV.
PubMed
2011-02-25
The differential cross section for the inclusive production of isolated prompt photons has been measured as a function of the photon transverse energy E(T)(γ) in pp collisions at √s=7 TeV using data recorded by the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.9 pb(-1). Photons are required to have a pseudorapidity |η(γ)|<1.45 and E(T)(γ)>21 GeV, covering the kinematic region 0.006cross section is found to be in agreement with next-to-leading-order perturbative QCD calculations.
10. Measurement of the Production Cross Section for Pairs of Isolated Photons in pp collisions at sqrt(s) = 7 TeV
SciTech Connect
Chatrchyan, S.; et al.,
2012-01-01
The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, $\\Delta(\\phi)$, less than approximately 2.8.
11. X-ray production cross sections at incident photon energies across the M{sub i} (i=1-5) edges of {sub 90}Th
SciTech Connect
Kaur, Rajnish; Shehla,; Kumar, Anil; Puri, Sanjiv
2015-08-28
The X-ray production cross sections for the M{sub k} (k= ξ, δ, α, β, ζ, γ, m{sub 1}, m{sub 2}) groups of X-rays have been evaluated at incident photon energies across the M{sub i} (i =1-5) edges of {sub 90}Th using the relativistic Hartree-Fock-Slater model based photoionisation cross sections and recently reported values of the M-shell X-ray emission rates, fluorescence and Coster Kronig yields. Further, the energies of the prominent (M{sub i}-S{sub j}) (S{sub j}=N{sub j}, O{sub j} and i =1-3, j =1-7) resonant Raman scattered (RRS) peaks at different incident photon energies have also been evaluated using the neutral-atom electron binding energies (E{sub sj}) based on the relaxed orbital relativistic Hartree-Fock-Slater model.
12. Measurement of the photon plus b-jet production differential cross section in $p\\bar{p}$ collisions at $\\sqrt{s}$ =1.96 TeV
SciTech Connect
Abazov, V. M.; Abbott, B; Acharya, B S; Adams, M; Adams, T; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Aoki, M; Askew, A; Atkins, S; Augsten, K; Avila, C; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Baringer, P; Barreto, J; Bartlett, J F; Bartosik, N; Bassler, U; Bazterra, V; Bean, A; Begalli, M; Bellantoni, L; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besancon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatia, S; Bhatnagar, V; Blazeay, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brandt, O; Brock, R; Brooijmans, G; Bross, A; Brown, D; Brown, J; Bu, X B; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Buszello, C P; Camacho-Perez, E; Casey, B C. K.; Castilla-Valdez, H; Caughron, S; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Chapon, E; Chen, G; Chevalier-Thery, S; Cho, D K; Cho, S W; Choi, S; Choudhary, B; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M -C; Croc, A; Cutts, D; Das, A; Davies, G; de Jong, S J; De La Cruz-Burelo, E; Deliot, F; Demina, R; Denisov, D; Denisov, S P; Desai, S; Deterre, C; DeVaughan, K; Diehl, H T; Diesburg, M; Ding, P F; Dominguez, A; Dubey, A; Dudko, L V; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Feng, L; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fuess, S; Garcia-Bellido, A; Garcia-Gonzalez, J A; Garcia-Guerra, G A; Gavrilov, V; Gay, R; Geng, W; Gerbaudo, D; Gerber, C E; Gershtein, Y; Ginther, G; Golovanov, G; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Grenier, G; Gris, Ph; Grivaz, J -F; Grohsjean, A; Gruenendahl, S; Gruenewald, M W; Guillemin, T; Gutierrez, G; Gutierrez, P; Haas, A; Hagopian, S; Haley, J; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Head, T; Hebbeker, T; Hedin, D; Hegab, H; Heinson, A P; Heintz, U; Hensel, C; Heredia-De La Cruz, I; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Howley, I; Hubacek, Z; Hynek, V; Iashvili, I; Ilchenko, Y; Illingworth, R; Ito, A S; Jabeen, S; Jaffre, M; Jayasinghe, A; Jesik, R; Johns, K; Johnson, E; Johnson, M; Jonckheere, A; Jonsson, R; Joshi, J; Jung, A W; Juste, A; Kaadze, K; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Kiselevich, I; Kohli, J M; Kozelov, A V; Kraus, J; Kulikov, S; Kumar, A; Kupco, A; Kurca, T; Kuzmin, V A; Lammers, S; Landsberg, G; Lebrun, P; Lee, H S; Lee, S W; Lee, W M; Lellouch, J; Li, H; Li, L; Li, Q Z; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, H; Liu, Y; Lobodenko, A; Lokajicek, M; de Sa, R Lopes; Lubatti, H J; Luna-Garcia, R; Lyon, A L; Maciel, A K. A.; Madar, R; Magana-Villalba, R; Malik, S; Malyshev, V L; Maravin, Y; Martinez-Ortega, J; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Menezes, D; Mercadante, P G; Merkin, M; Meyer, A; Meyer, J; et al.
2012-07-24
We present measurements of the differential cross section dσ/dργτ for the inclusive production of a photon in association with a b -quark jet for photons with rapidities |yγ| < 1.0 and 30 < ργτ < 300 GeV , as well as for photons with 1.5 <|yγ| < 2.5 and 30 < ργτ < 200 GeV, where ργτ is the photon transverse momentum. The b -quark jets are required to have pT > 15 GeV and rapidity |yjet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb-1, recorded with the D0 detector at the Fermilab Tevatron $p\\bar{p}$ Collider at $\\sqrt{s}$ =1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the SHERPA and PYTHIA Monte Carlo event generators.
13. Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at √s=7TeV
SciTech Connect
Chatrchyan, Serguei
2014-11-12
A measurement of differential cross sections for the production of a pair of isolated photons in proton–proton collisions at √s=7TeV is presented. The data sample corresponds to an integrated luminosity of 5.0fb-1 collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25GeV respectively, in the pseudorapidity range |η|<2.5, |η|ϵ[1.44,1.57] and with an angular separation ΔR>0.45, is 17.2±0.2(stat)±1.9(syst)±0.4(lumi) \\,pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins–Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.
14. Measurement of the production cross section of an isolated photon associated with jets in proton-proton collisions at s=7TeV with the ATLAS detector
2012-05-01
A measurement of the cross section for the production of an isolated photon in association with jets in proton-proton collisions at a center-of-mass energy s=7TeV is presented. Photons are reconstructed in the pseudorapidity range |ηγ|<1.37 and with a transverse energy ETγ>25GeV. Jets are reconstructed in the rapidity range |yjet|<4.4 and with a transverse momentum pTjet>20GeV. The differential cross section dσ/dETγ is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-pT jet: |yjet|<1.2, 1.2≤|yjet|<2.8 and 2.8≤|yjet|<4.4. For each rapidity configuration the same-sign (ηγyjet≥0) and opposite-sign (ηγyjet<0) cases are studied separately. The results are based on an integrated luminosity of 37pb-1, collected with the ATLAS detector at the LHC. Next-to-leading order perturbative QCD calculations are found to be in fair agreement with the data, except for ETγ≲45GeV, where the theoretical predictions overestimate the measured cross sections.
15. Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at [Formula: see text].
PubMed
A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at [Formula: see text] is presented. The data sample corresponds to an integrated luminosity of 5.0[Formula: see text] collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25[Formula: see text] respectively, in the pseudorapidity range [Formula: see text], [Formula: see text] and with an angular separation [Formula: see text], is [Formula: see text][Formula: see text]. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.
16. Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at √s=7TeV
DOE PAGES
Chatrchyan, Serguei
2014-11-12
A measurement of differential cross sections for the production of a pair of isolated photons in proton–proton collisions at √s=7TeV is presented. The data sample corresponds to an integrated luminosity of 5.0fb-1 collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25GeV respectively, in the pseudorapidity range |η|<2.5, |η|ϵ[1.44,1.57] and with an angular separation ΔR>0.45, is 17.2±0.2(stat)±1.9(syst)±0.4(lumi) \\,pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthalmore » angle difference between the two photons, and the cosine of the polar angle in the Collins–Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.« less
17. Single photon, photon-jet and diphoton production at DO
SciTech Connect
Abachi, S.; DO Collaboration
1995-07-01
Results are described on the observation of isolated single photons by the DO detector at the Fermilab {anti p}p collider. The inclusive cross section has been measured for photons in the central rapidity region ({vert_bar} {eta} {vert_bar}< 0.9) above 10 GeV E{sub T}. Studies of jets recoiling against the single photon permit the measurement of the fundamental hard scattering cos{theta}* distribution. An analysis of the {eta} correlations between high-E{sub T} photons and the leading jet probes the gluon x distribution. Diphoton production measurements are used both as a test of QCD processes and as a search for resonant structure, including bosonic Higgs production.
18. Direct Photon Production in a Nuclear Environment
Guo, Xiaofeng
The photon is a very good probe of short distance physics in strong interactions. It can be produced directly at short-distance or through fragmentation processes. Through one-loop order in perturbation theory of quantum chromodynamics (QCD), this thesis provides complete analytic expressions for both the inclusive and the isolated prompt photon production cross sections in hadronic final states of e^+e ^- annihilations. It is the first time that the full angular dependence of the cross sections is derived. Extraction of photon fragmentation functions from e^+e ^- annihilations is addressed. Using e ^+e^--->gamma+X as an example, this work demonstrates for the first time that conventional perturbative QCD factorization breaks down for isolated photon production in e^+e ^- annihilations in a specific region of phase space. The impact of this breakdown for computations of prompt photon production in hadron-hadron reactions is also discussed. In hadron-nucleus collisions, high energy photons can be produced through a single hard scattering as well as through multiple scattering. The contribution from the multiple scattering can be presented in terms of multi-parton correlation functions. Using information on the multi-parton correlation functions extracted from photon-nucleus experiments, for the first time, the nuclear dependence of direct photon production in hadron-nucleus collisions was predicted without any free parameter, and was tested at Fermi Lab experiment E706.
19. Theoretical X-ray production cross sections at incident photon energies across L{sub i} (i=1-3) absorption edges of Br
SciTech Connect
Puri, Sanjiv
2015-08-28
The X-ray production (XRP) cross sections, σ{sub Lk} (k = l, η, α, β{sub 6}, β{sub 1}, β{sub 3}, β{sub 4}, β{sub 9,10}, γ{sub 1,5}, γ{sub 2,3}) have been evaluated at incident photon energies across the L{sub i}(i=1-3) absorption edge energies of {sub 35}Br using theoretical data sets of different physical parameters, namely, the L{sub i}(i=1-3) sub-shell the X-ray emission rates based on the Dirac-Fock (DF) model, the fluorescence and Coster Kronig yields based on the Dirac-Hartree-Slater (DHS) model, and two sets of the photoionisation cross sections based on the relativistic Hartree-Fock-Slater (RHFS) model and the Dirac-Fock (DF) model, in order to highlight the importance of electron exchange effects at photon energies in vicinity of absorption edge energies.
20. Inclusive D*-meson production in two-photon collisions at LEP
Sokolov, A. A.
2002-06-01
The inclusive production of D*+ is measured by DELPHI in photon-photon collisions at LEP-II energies. The measured cross sections are compatible with the QCD calculations having the contributions from the resolved processes sensitive to the gluon density in photon. The total cross section of the charm quark production in two-photon collisions at LEP-II energies is estimated.
1. rho/sup 0/. omega. production in photon photon interactions
SciTech Connect
Derby, K.A.
1987-08-01
The subject of this dissertation is the production of the rho/sup 0/..omega.. final state in photon photon interactions. The production of the rho/sup 0/..omega.. final state has been of interest primarily because of its similarity to the related process ..gamma gamma.. ..-->.. rho/sup 0/rho/sup 0/. The cross section for rho/sup 0/rho/sup 0/ production demonstrates a peaking near threshold, the mechanism of which has been the subject of considerable speculation. The data sample used for the analysis was obtained using the TPC detector facility at the PEP e/sup +/e/sup -/ storage ring, and corresponds to an integrated e/sup +/e/sup -/ luminosity of 64 pb/sup -1/ at 29 GeV center of mass energy. Our estimate of the rho/sup 0/..omega.. cross section is compared to the predictions of several models which have been used to account for the observed rho/sup 0/rho/sup 0/ cross section. The experimental results are consistent with the predictions of a threshold enhancement model, as well as those of a four quark (qq anti q anti q) resonance model. However, they disagree with the predictions of a t-channel factorization approach.
2. Photon structure and the production of jets, hadrons, and prompt photons.
SciTech Connect
Klasen, M.
1999-07-22
We give a pedagogical introduction to hard photoproduction processes at HERA, including the production of jets, hadrons, and prompt photons. Recent theoretical developments in the three areas are reviewed. In summary, hard photoproduction processes can provide very useful information on the hadronic structure of the photon, in particular on the gluon density, which is complimentary to the information coming from deep inelastic photon-photon scattering at electron-positron colliders. Among the different hadronic final states, jets are most easily accessible experimentally and phenomenologically. On the other hand, inclusive hadron production offers the possibility to test the universality of hadron fragmentation functions and measure the photon structure down to very low values of p{sub T} and x{sub {gamma}}. Prompt photon production suffers from a reduced cross section and limited data, but allows for the additional testing of photon fragmentation functions.
3. Charmonium production in photon-photon collisions
SciTech Connect
Aihara, H.; Alston-Garnjost, M.; Avery, R.E.; Barbaro-Galtieri, A.; Barker, A.R.; Barnett, B.A.; Bauer, D.A.; Bengtsson, H.U.; Bobbink, G.J.; Bolognese, T.S.; Bross, A.D.; Buchanan, C.D.; Buijs, A.; Caldwell, D.O.; Chao, H.Y.; Chun, S.B.; Clark, A.R.; Cowan, G.D.; Crane, D.A.; Dahl, O.I.; Daoudi, M.; Derby, K.A.; Eastman, J.J.; Eberhard, P.H.; Edberg, T.K.; Eisner, A.M.; Enomoto, R.; Erne, F.C.; Fujii, T.; Gary, J.W.; Gorn, W.; Hauptman, J.M.; Hofmann, W.; Hylen, J.; Kamae, T.; Kaye, H.S.; Kees, K.H.; Kenney, R.W.; Winston, K.; Kofler, R.R.; Lander, R.L.; Langeveld, W.G.J.; Layter, J.G.; Lin, W.T.; Linde, F.L.; Loken, S.C.; Lu, A.; Lu, X.Q.; Lynch, G.R.; Madaras, R.J.; Maeshima, K.; Magnuson, B.D.; Masek, G.E.; Mathis, L.G.; Matthews, J.A.J.; Maxfield, S.J.; Miller, E.S.; Moses, W.; McNeil, R.R.; Nygren, D.R.; Oddone, P.R.; Paar, H.P.; Park, S.K.; Pellett, D.E.; Pripstein, M.; Ronan, M.T.; Ross, R.R.; Rouse, F.R.; Schwitkis, K.A.; Sens, J.C.; Shapiro, G.; Shen, B.C.; Slater, W.E.; Smit
1987-01-01
We have searched for the two-photon production of the /eta//sub c/, /chi//sub 0/ and /chi//sub 2/ charmonium states at the e/sup +/e/sup -/ collider PEP in the channels /gamma//gamma/ /yields/ K/sup +-/K/sub S//sup 0//pi//sup -+/, /gamma//gamma/ /yields/ K/sup +/K/sup -//pi//sup +//pi//sup -/, /gamma//gamma/ /yields/ /pi//sup +//pi//sup -//pi//sup +//pi//sup -/ and /gamma//gamma/ /yields/ K/sup +/K/sup -/K/sup +/K/sup -/. We identify four /eta//sub c/ candidates in the K/sup +/K/sup -/K/sup +/K/sup -/ channel, on a negligible background; this leads to a preliminary 95% C.L. lower limit for /Gamma//sub /gamma//gamma//(/eta//sup c/) of 1.6 keV. In the other channels we find no evidence for any of the three states and establish preliminary 95% C.L. upper limits /Gamma//sub /gamma//gamma//(/eta//sub c/) < 15 keV, /Gamma//sub /gamma//gamma//(/chi//sub 0/)< 14 keV and /Gamma//sub /gamma//gamma//(/chi//sub 2/) < 4.0 keV. Combining the results on the /eta//sub c/ from all channels we obtain the value /Gamma//sub /gamma//gamma//(/eta//sub c/) = 4.5/sub -3.6///sup -5.5 keV. 18 refs., 3 figs., 1 tab.
4. Measurement of the cross section for direct-photon production in association with a heavy quark in pp[over ¯] collisions at sqrt[s]=1.96 TeV.
PubMed
Aaltonen, T; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Butti, P; Buzatu, A; Calamba, A; Camarda, S; Campanelli, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Cho, K; Chokheli, D; Ciocci, M A; Clark, A; Clarke, C; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Cremonesi, M; Cruz, D; Cuevas, J; Culbertson, R; d'Ascenzo, N; Datta, M; De Barbaro, P; Demortier, L; Deninno, M; d'Errico, M; Devoto, F; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dorigo, M; Driutti, A; Ebina, K; Edgar, R; Elagin, A; Erbacher, R; Errede, S; Esham, B; Eusebi, R; Farrington, S; Fernández Ramos, J P; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Frisch, H; Funakoshi, Y; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González López, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gramellini, E; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Han, J Y; Happacher, F; Hara, K; Hare, M; Harr, R F; Harrington-Taber, T; Hatakeyama, K; Hays, C; Heinrich, J; Herndon, M; Hocker, A; Hong, Z; Hopkins, W; Hou, S; Hughes, R E; Husemann, U; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kambeitz, M; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y J; Kim, Y K; Kimura, N; Kirby, M; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Kruse, M; Kuhr, T; Kurata, M; Laasanen, A T; Lammel, S; Lancaster, M; Lannon, K; Latino, G; Lee, H S; Lee, J S; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lipeles, E; Lister, A; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucà, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, P; Martínez, M; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M J; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Nigmanov, T; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagliarone, C; Palencia, E; Palni, P; Papadimitriou, V; Parker, W; Pauletta, G; Paulini, M; Paus, C; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Pranko, A; Prokoshin, F; Ptohos, F; Punzi, G; Ranjan, N; Redondo Fernández, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodriguez, T; Rolli, S; Ronzani, M; Roser, R; Rosner, J L; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, E E; Schwarz, T; Scodellaro, L; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sinervo, P; Sliwa, K; Smith, J R; Snider, F D; Song, H; Sorin, V; Stancari, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thomson, E; Thukral, V; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Vázquez, F; Velev, G; Vellidis, C; Vernieri, C; Vidal, M; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wallny, R; Wang, S M; Warburton, A; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wilbur, S; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Zanetti, A M; Zeng, Y; Zhou, C; Zucchelli, S
2013-07-26
We report on a measurement of the cross section for direct-photon production in association with a heavy quark using the full data set of sqrt[s]=1.96 TeV proton-antiproton collisions corresponding to 9.1 fb-1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron. The measurements are performed as a function of the photon transverse momentum, covering a photon transverse momentum between 30 and 300 GeV, photon rapidities |yγ|<1.0, a heavy-quark-jet transverse momentum pTjet>20 GeV, and jet rapidities |yjet|<1.5. The results are compared with several theoretical predictions.
5. Isolated double prompt photon production at CDF
SciTech Connect
Harris, R.M.
1992-11-04
We present a measurement of the cross section for production of two isolated prompt photons in p[bar p] collisions at [radical]s = 1.8 TeV. The cross section, measured as a function of transverse momentum (PT) of each photon, is roughly three times what full QCD calculations predict. Calculations that only include the Born and box diagrams, which are commonly used to estimate the prompt diphoton background to Higgs decay at future hadron colliders, are lower than our measurement by roughly ii factor of five. We also study variables sensitive to K[sub T]: the transverse momentum of initial state partons. The vector sum of the transverse momenta of both photons, K[sub T] = [vert bar][rvec P][sub T1] + [rvec P][sub T2][vert bar], is compared to previous measurements at lower collision energies, and we find a roughly logarithmic increase with [radical]s. The measured mean value is < K[sub T] >= 5.1 [plus minus] 1.1 GeV at [radical]s = 1.8 TeV.
6. Measurement of the triple-differential cross section for photon+jets production in proton-proton collisions at √s = 7 TeV
DOE PAGES
Chatrchyan, Serguei
2013-06-03
A measurement of the triple-differential cross section,more » $${{{{{\\mathrm{d}}^3}\\sigma }} \\left/ {{\\left( {\\mathrm{d}\\mathrm{p}_T^{\\gamma}\\mathrm{d}{\\eta^{\\gamma }}\\mathrm{d}{\\eta^{\\mathrm{jet}}}} \\right)}} \\right.}$$ , in photon + jets final states using a data sample from proton-proton collisions at $$\\sqrt{s}$$ = 7 TeV is presented. This sample corresponds to an integrated luminosity of 2.14 fb$$^{-1}$$ collected by the CMS detector at the LHC. Photons and jets are reconstructed within a pseudorapidity range of |η| < 2.5, and are required to have transverse momenta in the range 40 < $$p_{\\mathrm{T}}^{\\mathrm{jet}}$$ < 300 GeV and $$p_{\\mathrm{T}}^{\\mathrm{jet}}$$ > 30 GeV, respectively. The measurements are compared to theoretical predictions from the sherpa leading-order QCD Monte Carlo event generator and the next-to-leading-order perturbative QCD calculation from jetphox. Lastly, the predictions are found to be consistent with the data over most of the examined kinematic region.« less
7. Measurement of the triple-differential cross section for photon+jets production in proton-proton collisions at √s = 7 TeV
SciTech Connect
Chatrchyan, Serguei
2013-06-03
A measurement of the triple-differential cross section, ${{{{{\\mathrm{d}}^3}\\sigma }} \\left/ {{\\left( {\\mathrm{d}\\mathrm{p}_T^{\\gamma}\\mathrm{d}{\\eta^{\\gamma }}\\mathrm{d}{\\eta^{\\mathrm{jet}}}} \\right)}} \\right.}$ , in photon + jets final states using a data sample from proton-proton collisions at $\\sqrt{s}$ = 7 TeV is presented. This sample corresponds to an integrated luminosity of 2.14 fb$^{-1}$ collected by the CMS detector at the LHC. Photons and jets are reconstructed within a pseudorapidity range of |η| < 2.5, and are required to have transverse momenta in the range 40 < $p_{\\mathrm{T}}^{\\mathrm{jet}}$ < 300 GeV and $p_{\\mathrm{T}}^{\\mathrm{jet}}$ > 30 GeV, respectively. The measurements are compared to theoretical predictions from the sherpa leading-order QCD Monte Carlo event generator and the next-to-leading-order perturbative QCD calculation from jetphox. Lastly, the predictions are found to be consistent with the data over most of the examined kinematic region.
8. Measurement of prompt photon cross-section with the ATLAS detector
Ishmukhametov, Renat
The thesis presents the result of the measurement of the prompt photons production cross-section with the ATLAS detector on the Large Hadron Collider using 2010 data at 7 TeV center of mass energy. The measurement is done using two datasets, one for lower value of the transverse energy, another one is for the higher value of the transverse energy. A good agreement with the theoretical prediction is observed,The thesis presents the measurement of the prompt photon production cross-section with the ATLAS detector at the Large Hadron Collider using 2010 data at 7 TeV center of mass energy. The measurement is done using two datasets, and for different values of photon transverse energy, ET. The first measurement, made for photons with ET>15 GeV, uses 880 nb-1 of collision data, and the second measurement, relevant for photons with ET>45 GeV, uses 35 pb-1 of data. Good agreement with the theoretical prediction for the cross-section is observed, especially for the higher transverse energy photons. This thesis also contains the result of the measurement of the electronic crosstalk in the ATLAS liquid argon calorimeter, important for the photon calibration and calorimeter commissioning. especially with the higher transverse energy photons. The thesis also contains the results of the measurement of the electronic crosstalk in the ATLAS liquid argon calorimeter, important for the photon calibration and calorimeter commissioning.
9. Large conditional single-photon cross-phase modulation
PubMed Central
Hosseini, Mahdi; Duan, Yiheng; Vuletić, Vladan
2016-01-01
Deterministic optical quantum logic requires a nonlinear quantum process that alters the phase of a quantum optical state by π through interaction with only one photon. Here, we demonstrate a large conditional cross-phase modulation between a signal field, stored inside an atomic quantum memory, and a control photon that traverses a high-finesse optical cavity containing the atomic memory. This approach avoids fundamental limitations associated with multimode effects for traveling optical photons. We measure a conditional cross-phase shift of π/6 (and up to π/3 by postselection on photons that remain in the system longer than average) between the retrieved signal and control photons, and confirm deterministic entanglement between the signal and control modes by extracting a positive concurrence. By upgrading to a state-of-the-art cavity, our system can reach a coherent phase shift of π at low loss, enabling deterministic and universal photonic quantum logic. PMID:27519798
10. Observation of top-quark pair production in association with a photon and measurement of the t t ¯ γ production cross section in p p collisions at √{s }=7 TeV using the ATLAS detector
2015-04-01
A search is performed for top-quark pairs (t t ¯) produced together with a photon (γ ) with transverse energy greater than 20 GeV using a sample of t t ¯ candidate events in final states with jets, missing transverse momentum, and one isolated electron or muon. The data set used corresponds to an integrated luminosity of 4.59 fb-1 of proton-proton collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. In total, 140 and 222 t t ¯γ candidate events are observed in the electron and muon channels, to be compared to the expectation of 79 ±26 and 120 ±39 non-t t ¯γ background events, respectively. The production of t t ¯γ events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The t t ¯γ production cross section times the branching ratio (BR) of the single-lepton decay channel is measured in a fiducial kinematic region within the ATLAS acceptance. The measured value is σtt ¯ γ fid×BR =63 ±8 (stat)-13+17(syst)±1 (lumi) fb per lepton flavor, in good agreement with the leading-order theoretical calculation normalized to the next-to-leading-order theoretical prediction of 48 ±10 fb .
11. Heavy flavor production from photons and hadrons
SciTech Connect
Heusch, C.A.
1982-01-01
The present state of the production and observation of hadrons containing heavy quarks or antiquarks as valence constituents, in reactions initiated by real and (space-like) virtual photon or by hadron beams is discussed. Heavy flavor production in e/sup +/e/sup -/ annihilation, which is well covered in a number of recent review papers is not discussed, and similarly, neutrino production is omitted due to the different (flavor-changing) mechanisms that are involved in those reactions. Heavy flavors from spacelike photons, heavy flavors from real photons, and heavy flavors from hadron-hadron collisions are discussed. (WHK)
12. Measurement of the production cross section of an isolated photon associated with jets in proton-proton collisions at root s=7 TeV with the ATLAS detector
SciTech Connect
2012-05-23
A measurement of the cross section for the production of an isolated photon in association with jets in proton-proton collisions at a center-of-mass energy {radical}s = 7 TeV is presented. Photons are reconstructed in the pseudorapidity range |{eta}{sup y}| < 1.37 and with a transverse energy E{sub T}{sup y} > 25 GeV. Jets are reconstructed in the rapidity range |y{sup jet}| < 4.4 and with a transverse momentum p{sub T}{sup jet} > 20 GeV. The differential cross section d{sigma}/dE{sub T}{sup y} is measured, as a function of the photon transverse energy, for three different rapidity ranges of the leading-p{sub T} jet: |y{sup jet}| < 1.2, 1.2 {le} |y{sup jet}| < 2.8 and 2.8 {le} |y{sup jet}| < 4.4. For each rapidity configuration the same-sign ({eta}{sup y} y{sup jet} {ge} 0) and opposite-sign ({eta}{sup y} y{sup jet} < 0) cases are studied separately. The results are based on an integrated luminosity of 37 pb{sup -1}, collected with the ATLAS detector at the LHC. Next-to-leading order perturbative QCD calculations are found to be in fair agreement with the data, except for E{sub T}{sup y} {approx}< 45 GeV, where the theoretical predictions overestimate the measured cross sections.
13. Direct photon production in e+e- annihilation
Fernandez, E.; Ford, W. T.; Qi, N.; Read, A. L.; Smith, J. G.; Camporesi, T.; de Sangro, R.; Marini, A.; Peruzzi, I.; Piccolo, M.; Ronga, F.; Blume, H. T.; Hurst, R. B.; Sleeman, J. C.; Venuti, J. P.; Wald, H. B.; Weinstein, Roy; Band, H. R.; Gettner, M. W.; Goderre, G. P.; Meyer, O. A.; Moromisato, J. H.; Shambroom, W. D.; von Goeler, E.; Ash, W. W.; Chadwick, G. B.; Clearwater, S. H.; Coombes, R. W.; Kaye, H. S.; Lau, K. H.; Leedy, R. E.; Lynch, H. L.; Messner, R. L.; Moss, L. J.; Muller, F.; Nelson, H. N.; Ritson, D. M.; Rosenberg, L. J.; Wiser, D. E.; Zdarko, R. W.; Groom, D. E.; Lee, H. Y.; Delfino, M. C.; Heltsley, B. K.; Johnson, J. R.; Lavine, T. L.; Maruyama, T.; Prepost, R.
1985-01-01
Direct photon production in hadronic events from e+e- annihilation has been studied at √s =29 GeV with use of the MAC detector at the PEP storage ring. A charge asymmetry A=(-12.3+/-3.5)% is observed in the final-state jets. The cross section and the charge asymmetry are in good agreement with the predictions of the fractionally charged quark-parton model. Both the charge asymmetry and total yield have been used to determine values of quark charges. Limits have been established for anomalous sources of direct photons.
14. Magnetic two-photon scattering and two-photon emission - Cross sections and redistribution functions
NASA Technical Reports Server (NTRS)
Alexander, S. G.; Meszaros, P.
1991-01-01
The magnetic two-photon scattering cross section is discussed within the framework of QED, and the corresponding scattering redistribution function for this process and its inverse, as well as the scattering source function are calculated explicitly. In a similar way, the magnetic two-photon emission process which follows the radiative excitation of Landau levels above ground is calculated. The two-photon scattering and two-photon emission are of the same order as the single-photon magnetic scattering. All three of these processes, and in optically thick cases also their inverses, are included in radiative transport calculations modeling accreting pulsars and gamma-ray bursters. These processes play a prominent role in determining the relative strength of the first two cyclotron harmonics, and their effects extend also to the higher harmonics.
15. Higgs boson pair production at a photon-photon collision in the two Higgs doublet model
2009-03-01
We calculate the cross section of Higgs boson pair production at a photon collider in the two Higgs doublet model. We focus on the scenario in which the lightest CP even Higgs boson (h) has the Standard Model like couplings to the gauge bosons. We take into account the one-loop correction to the hhh coupling as well as additional one-loop diagrams due to charged Higgs bosons to the γγ → hh helicity amplitudes. It is found that the full cross section can be enhanced by both these effects to a considerable level. We discuss the impact of these corrections on the hhh coupling measurement at the photon collider.
16. Partial cross sections of helium satellites at medium photon energies
SciTech Connect
Wehlitz, R.; Sellin, I.A.; Hemmers, O.
1997-04-01
Still of current interest is the important role of single ionization with excitation compared to single ionization alone. The coupling between the electrons and the incoming photon is a single-particle operator. Thus, an excitation in addition to an ionization, leading to a so-called satellite line in a photoelectron spectrum, is entirely due to electron-electron interaction and probes the electron correlation in the ground and final state. Therefore the authors have undertaken the study of the intensity of helium satellites He{sup +}nl (n = 2 - 6) relative to the main photoline (n = 1) as a function of photon energy at photon energies well above threshold up to 900 eV. From these results they could calculate the partial cross-sections of the helium satellites. In order to test the consistency of their satellite-to-1s ratios with published double-to-single photoionization ratios, the authors calculated the double-to-single photoionization ratio from their measured ratios using the theoretical energy-distribution curves of Chang and Poe and Le Rouzo and Dal Cappello which proved to be valid for photon energies below 120 eV. These calculated double-to-single ionization ratios agree fairly well with recent ion measurements. In the lower photon energy range the authors ratios agree better with the ratios of Doerner et al. while for higher photon energies the agreement is better with the values of Levin et al.
17. High resolution cross strip anodes for photon counting detectors
Siegmund, O. H. W.; Tremsin, A. S.; Vallerga, J. V.; Abiad, R.; Hull, J.
2003-05-01
A new photon counting, imaging readout for microchannel plate sensors, the cross strip (XS) anode, has been investigated. Charge centroiding of signals detected on two orthogonal layers of sense strip sets are used to derive photon locations. The XS anode spatial resolution (<3 μm FWHM) exceeds the spatial resolution of most direct charge sensing anodes, and does so at low gain (<2×10 6). The image linearity and fidelity are high enough to resolve and map 7 μm MCP pores, offering new possibilities for astronomical and other applications.
18. Isolated prompt photon production at CDF
SciTech Connect
Maas, P.A. )
1992-11-01
This note describes measurements of isolated prompt photon production at [radical]s = 1.8 TeV using the CDF experiment. The measurements are compared to recent NLO QCD calculations, including recently obtained parton distribution functions. Qualitatively, the QCD calculation with the new parton distribution functions agrees better with the data than the previous parton distribution functions.
19. Isolated prompt photon production at CDF
SciTech Connect
Maas, P.A.; CDF Collaboration
1992-11-01
This note describes measurements of isolated prompt photon production at {radical}s = 1.8 TeV using the CDF experiment. The measurements are compared to recent NLO QCD calculations, including recently obtained parton distribution functions. Qualitatively, the QCD calculation with the new parton distribution functions agrees better with the data than the previous parton distribution functions.
20. Neutral Higgs boson pair production in photon-photon annihilation in the two Higgs doublet model
SciTech Connect
Arhrib, Abdesslam; Benbrik, Rachid; Chen, C.-H.; Santos, Rui
2009-07-01
We study double Higgs production in photon-photon collisions as a probe of the new dynamics of Higgs interactions in the framework of two Higgs doublet models. We analyze neutral Higgs bosons production and decay in the fusion processes, {gamma}{gamma}{yields}S{sub i}S{sub j}, S{sub i}=h{sup 0}, H{sup 0}, A{sup 0}, and show that both h{sup 0}h{sup 0} and A{sup 0}A{sup 0} production can be enhanced by threshold effects in the region E{sub {gamma}}{sub {gamma}}{approx_equal}2m{sub H{+-}}. Resonant effects due to the heavy Higgs H{sup 0} can also play a role in the cross section enhancement when it is allowed to decay to two light CP-even h{sup 0} or to two light CP-odd A{sup 0} scalars. We have scanned the allowed parameter space of the two Higgs doublet model and found a vast region of the parameter space where the cross section is 2 orders of magnitude above the standard model cross section. We further show that the standard model experimental analysis can be used to discover or to constrain the two Higgs doublet model parameter space.
1. Cross two photon absorption in a silicon photonic crystal waveguide fiber taper coupler with a physical junction
SciTech Connect
Sarkissian, Raymond O'Brien, John
2015-01-21
Cross two photon absorption in silicon is characterized using a tapered fiber photonic crystal silicon waveguide coupler. There is a physical junction between the tapered fiber and the waveguide constituting a stand-alone device. This device is used to obtain the spectrum for cross two photon absorption coefficient per unit volume of interaction between photons of nondegenerate energy. The corresponding Kerr coefficient per unit volume of interaction is also experimentally extracted. The thermal resistance of the device is also experimentally determined and the response time of the device is estimated for on-chip all-optical signal processing and data transfer between optical signals of different photon energies.
2. Ratio of Isolated Photon Cross Sections in ppbar Collisions at √s = 630 and 1800 GeV
2001-12-01
The inclusive cross section for production of isolated photons has been measured in ppbar collisions at (s) = 630 GeV with the D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy (ET) range from 7-49 GeV and have pseudorapidity \\|η\\|<2.5. This measurement is combined with the previous D0 result at (s) = 1800 GeV to form a ratio of the cross sections. Comparison of next-to-leading-order QCD with the measured cross section at 630 GeV and the ratio of cross sections show satisfactory agreement in most of the ET range.
3. NLO QCD corrections for J /ψ +c +c ¯ production in photon-photon collision
Chen, Zi-Qiang; Chen, Long-Bin; Qiao, Cong-Feng
2017-02-01
The γ +γ →J /ψ +c +c ¯ inclusive process is an extremely important subprocess in J /ψ production via photon-photon scattering, like at LEPII or various types of future electron-positron colliders. In this work we perform the next-to-leading order (NLO) QCD corrections to this process in the framework of nonrelativistic QCD (NRQCD) factorization formalism, the first NLO calculation for two projectiles to the 3-body quarkonium inclusive production process. By setting the center-of-mass energy at LEPII, the √{s }=197 GeV , we conduct analyses of the pt2 distribution and total cross section of this process at the NLO accuracy. It turns out that the total cross section is moderately enhanced by the NLO correction with a K factor of about 1.46, and hence the predicted J /ψ inclusive productivity is increased while the DELPHI data still overshoot the theoretical prediction. At the future Circular Electron-Positron Collider, the NLO corrections are found to be more significant, with a K factor of about 1.76.
4. Undulator-Based Production of Polarized Photons
SciTech Connect
Professor Kirk McDonald
2008-05-29
"Project Title: Undulator-Based Production of Polarized Photons" DOE Contract Number: FG02-04ER41355 Principal Investigator: Prof. Kirk McDonald Period of Performance: 09/10/2004 thru 08/31/2006 This award was to fund Princeton's activity on SLAC experiment E166, "Undulator-Based Production of Polarized Positrons" which was performed at SLAC during June and September 2005. Princeton U. fabricated a magnetic spectrometer for this experiment, and participated in the commissioning, operation, and analysis of the experiment, for which Prof. McDonald was a co-spokesperson. The experiment demonstrated that an intense positron beam with 80% longitudinal polarization could be generated by conversion of MeVenergy circularly polarized photons in a thin target, which photons were generated by passage of high-energy electrons through a helical undulator. This technique has since been adopted as the baseline for the polarized positron source of the proposed International Linear Collider. Results of the experiment have been published in Physical Review Letters, vol 100, p 210801 (2008) [see attached .pdf file], and a longer paper is in preparation.
5. Diphoton and photon + b/c cross sections at CDF II
SciTech Connect
Bocci, A.; /Rockefeller U.
2004-12-01
A measurement of the rate of prompt diphoton production in p{bar p} collisions at {radical}s = 1.96 TeV using the CDF detector is presented. The results are compared to a NLO calculation. they also measured the {gamma} + b and {gamma} + c cross sections comparing the results with PYTHIA LO predictions. The background from non-prompt sources is estimated using a statistical method based on differences in electromagnetic showers initiated by photons and by the background.
6. Electroweak radiative corrections to triple photon production at the ILC
Zhang, Yu; Li, Wei-Hua; Duan, Peng-Fei; Song, Mao; Li, Gang
2016-07-01
In this paper, we present the precision predictions for three photon production in the standard model (SM) at the ILC including the full next-to-leading (NLO) electroweak (EW) corrections, high order initial state radiation (h.o.ISR) contributions and beamstrahlung effects. We present the LO and the NLO EW + h.o.ISR + beamstrahlung corrected total cross sections for various colliding energy when √{ s} ≥ 200 GeV and the kinematic distributions of final photons with √{ s} = 500 GeV at ILC, and find that the NLO EW corrections, the h.o.ISR contributions and the beamstrahlung effects are important in exploring the process e+e- → γγγ.
7. Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments
SciTech Connect
Hagmann, C; Pruet, J
2006-10-26
The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence.
8. Exclusive e+e-, di-photon and di-jet production at the Tevatron
SciTech Connect
Terashi, Koji; /Rockefeller U.
2007-05-01
Results from studies on exclusive production of electron-position pair, di-photon, and dijet production at CDF in proton-antiproton collisions at the Fermilab Tevatron are presented. THe first observation and cross section measurements of exclusive e{sup +}e{sup -} and di-jet production in hadron-hadron collisions are emphasized.
9. Electroweak corrections to top quark pair production in association with a hard photon at hadron colliders
Duan, Peng-Fei; Zhang, Yu; Wang, Yong; Song, Mao; Li, Gang
2017-03-01
We present the next-to-leading order (NLO) electroweak (EW) corrections to the top quark pair production associated with a hard photon at the current and future hadron colliders. The dependence of the leading order (LO) and NLO EW corrected cross sections on the photon transverse momentum cut are investigated. We also provide the LO and NLO EW corrected distributions of the transverse momentum of final top quark and photon and the invariant mass of top quark pair and top-antitop-photon system. The results show that the NLO EW corrections are significant in high energy regions due to the EW Sudakov effect.
10. Photon plus heavy-quark production in high-energy collisions within the target rest frame formalism
SciTech Connect
Betemps, M. A.; Machado, M. V. T.
2010-11-01
We apply the target rest frame formalism to photon+heavy quark production cross section in hadronic collisions at high energies. We investigate the dependence of the production cross section on the photon and quark rapidities and transverse momenta. It is shown that the photon transverse momentum spectrum is a sensitive probe of color dipole scattering amplitude. The theoretical results are compared to Tevatron measurements of the differential {gamma}+c+X and {gamma}+b+X production cross sections at {radical}(s)=1.96 TeV. An analysis for proton-proton and proton-lead collisions at the LHC regime is also performed.
11. Stopping powers and cross sections due to two-photon processes in relativistic nucleus-nucleus collisions
NASA Technical Reports Server (NTRS)
Cheung, Wang K.; Norbury, John W.
1994-01-01
The effects of electromagnetic-production processes due to two-photon exchange in nucleus-nucleus collisions are discussed. Feynman diagrams for two-photon exchange are evaluated using quantum electrodynamics. The total cross section and stopping power for projectile and target nuclei of identical charge are found to be significant for heavy nuclei above a few GeV per nucleon-incident energy.
12. Photon-jet cross sections in deep-inelastic scattering
Aurenche, P.; Fontannaz, M.
2015-02-01
We present the complete next-to-leading order calculation of isolated prompt photon production in association with a jet in deep-inelastic scattering. The calculation involves, direct, resolved, and fragmentation contributions. It is shown that defining the transverse momenta in the proton virtual-photon frame (CM), as usually done, or in the laboratory frame, as done in some experiments, is not equivalent and leads to important differences concerning the perturbative approach. In fact, using the latter frame may preclude, under certain conditions, the calculation of the next-to-leading order correction to the important resolved component. A comparison with the latest ZEUS data is performed and good agreement is found in the perturbatively stable regions.
13. Measurement of the differential cross section of photon plus jet production in $pp¯$ collisions at $s=1.96 TeV$
SciTech Connect
2013-10-01
We study the process of associated photon and jet production, p+$\\bar{p}$→ photon + jet + X, using 8.7 fb-1 of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy √s=1.96 TeV. Photons are reconstructed with rapidity |yγ| <1.0 or 1.5<|yγ| < 2.5 and transverse momentum pT$γ\\atop{T}$ > 20 GeV. The highest-pT jet is required to be in one of four rapidity regions up to |yjet|< 3.2. For each rapidity configuration we measure the differential cross sections in p$γ\\atop{T}$ separately for events with the same sign (yγ yjet>0) and opposite sign (yγ yjet<=0) of photon and jet rapidities. We compare the measured triple differential cross sections, d3 sigma / d p$γ\\atop{T}$ yγ yjet, to next-to-leading order (NLO) perturbative QCD calculations using different sets of parton distribution functions and to predictions from the SHERPA and PYTHIA Monte Carlo event generators. The NLO calculations are found to be in general agreement with the data, but do not describe all kinematic regions.
14. Measurement of Prompt Photon Production in 1.8-TeV Proton - Antiproton Collisions
SciTech Connect
Ino, Takashi
1996-06-01
The inclusive production cross section of prompt photons with transverse energies 27 < EtEt < 40 GeV and in pseudorapidity 1.32 < ηη < 2.22 has been measured in proton antiproton collisions at s√s = 1.8 TeV. Using the data recorded by the CDF detector during the 1988-1989 TEVATRON collider run, corresponding to an integrated lurminosity of 3.8 ± 0.1 pb-1 3995 prompt photon candidate events are selected in the endplug electromagnetic calorimeter. From differences in the longitudinal cascade shower profile between a single photon and multi-photons from π0π0 and ηη meson decays, the number of prompt photon events in the candidates is extracted to be 1972 ± 353.The differences in the shower shape are obtained by a GEANT3 based Monte Carlo detector simulation, which has been careful1y studied and found to wel1 reproduce the electromagnetic cascade of electrons at various energies as wel1 as incident angles. The inclusive production cross section has been obtained to be σσ = 1.44 ± 0.09(stat..) ± 0.27(syst.) nb. The measurement agrees with the next-to-leading order QCD calculation using recent parton distribution functions. The differential cross section with respect to pseudorapidity has also been measured and found to be in good agreement with the QCD calculation. The photon event fraction and its dependence on the photon isolation are studied. The isolation dependence of the photon event fraction shows a consistency with the QCD prediction. Future prospects of prompt photon measurernents in the endplug region for the new data, which has been col1ected during 1992 to 1995 correspondingto roughly 110 pb-1 are also discussed.
15. Pion and kaon pair production in photon-photon collisions
SciTech Connect
Aihara, H.; Alston-Garnjost, M.; Avery, R.E.; Barbaro-Galtieri, A.; Barker, A.R.; Barnes, A.V.; Barnett, B.A.; Bauer, D.A.; Bengtsson, H.; Bintinger, D.L.; Blumenfeld, B.J.; Bobbink, G.J.; Bross, A.D.; Buchanan, C.D.; Buijs, A.; Cain, M.P.; Caldwell, D.O.; Chamberlain, O.; Chien, C.; Clark, A.R.; Cowan, G.D.; Crane, D.A.; Dahl, O.I.; Derby, K.A.; Eastman, J.J.; Eberhard, P.H.; Eisner, A.M.; Enomoto, R.; Erne-acute-accent, F.C.; Fujii, T.; Gabioud, B.; Gary, J.W.; Gorn, W.; Hauptman, J.M.; Hofmann, W.; Huth, J.E.; Hylen, J.; Joshi, U.P.; Kamae, T.; Kaye, H.S.; Kees, K.H.; Kenney, R.W.; Kerth, L.T.; Ko, W.; Koda, R.I.; Kofler, R.R.; Kwong, K.K.; Lander, R.L.; Langeveld, W.G.J.; Layter, J.G.; Linde, F.L.; Lindsey, C.S.; Loken, S.C.; Lu, A.; Lu, X.; Lynch, G.R.; Madaras, R.J.; Maeshima, K.; Magnuson, B.D.; Marx, J.N.; Maruyama, K.; Masek, G.E.; Mathis, L.G.; Matthews, J.A.J.; Maxfield, S.J.; Melnikoff, S.O.; Miller, E.S.; Moses, W.; McNeil, R.R.; Nemethy, P.; Nygren, D.R.; Oddone, P.J.; Pa
1986-07-28
We report measurements of the two-photon processes e-italic/sup +/e/sup -/..-->..e/sup +/e/sup -/..pi../sup +/..pi../sup -/ and e-italic/sup +/e/sup -/..-->..e/sup +/e/sup -/K/sup +/K/sup -/, at an e-italic/sup +/e/sup -/ center-of-mass energy of 29 GeV. In the ..pi../sup +/..pi../sup -/ data a high-statistics analysis of the f-italic(1270) results in a ..gamma gamma.. width GAMMA(..gamma gamma -->..f-italic) = 3.2 +- 0.4 keV. The ..pi../sup +/..pi../sup -/ continuum below the f-italic mass is well described by a QED Born approximation, whereas above the f-italic mass it is consistent with a QCD-model calculation if a large contribution from the f-italic is assumed. For the K-italic/sup +/K/sup -/ data we find agreement of high-mass continuum with the QCD prediction; limits on f-italic'(1520) and t-italich-italice-italict-italica-italic(1720) formation are presented.
16. Two-photon induced collagen cross-linking in bioartificial cardiac tissue
Kuetemeyer, Kai; Kensah, George; Heidrich, Marko; Meyer, Heiko; Martin, Ulrich; Gruh, Ina; Heisterkamp, Alexander
2011-08-01
Cardiac tissue engineering is a promising strategy for regenerative therapies to overcome the shortage of donor organs for transplantation. Besides contractile function, the stiffness of tissue engineered constructs is crucial to generate transplantable tissue surrogates with sufficient mechanical stability to withstand the high pressure present in the heart. Although several collagen cross-linking techniques have proven to be efficient in stabilizing biomaterials, they cannot be applied to cardiac tissue engineering, as cell death occurs in the treated area. Here, we present a novel method using femtosecond (fs) laser pulses to increase the stiffness of collagen-based tissue constructs without impairing cell viability. Raster scanning of the fs laser beam over riboflavin-treated tissue induced collagen cross-linking by two-photon photosensitized singlet oxygen production. One day post-irradiation, stress-strain measurements revealed increased tissue stiffness by around 40% being dependent on the fibroblast content in the tissue. At the same time, cells remained viable and fully functional as demonstrated by fluorescence imaging of cardiomyocyte mitochondrial activity and preservation of active contraction force. Our results indicate that two-photon induced collagen cross-linking has great potential for studying and improving artificially engineered tissue for regenerative therapies.
17. Femtosecond correlated photon echo in CdS crystal under two-photon excitation by two pairs of crossed laser beams
Samartsev, V. V.; Leontiev, A. V.; Mitrofanova, T. G.
2015-07-01
We consider the possibility of observing a femtosecond correlated photon echo (FCPE) under two-photon excitation of CdS crystal by two pairs of crossed laser beams. The peculiarities of FCPE signals and their possible applications are discussed.
18. THE PAIR BEAM PRODUCTION SPECTRUM FROM PHOTON-PHOTON ANNIHILATION IN COSMIC VOIDS
SciTech Connect
Schlickeiser, R.; Ibscher, D.; Elyiv, A.; Miniati, F. E-mail: [email protected] E-mail: [email protected]
2012-10-20
Highly beamed relativistic e {sup {+-}}-pair energy distributions result in double photon collisions of the beamed gamma rays from TeV blazars at cosmological distances with the isotropically distributed extragalactic background light (EBL) in the intergalactic medium. The typical energies k {sub 0} {approx_equal} 10{sup -7} in units of m{sub e}c {sup 2} of the EBL are more than 10 orders of magnitude smaller than the observed gamma-ray energies k {sub 1} {>=} 10{sup 7}. Using the limit k {sub 0} << k {sub 1}, we demonstrate that the angular distribution of the generated pairs in the lab frame is highly beamed in the direction of the initial gamma-ray photons. For the astrophysically important case of power-law distributions of the emitted gamma-ray beam up to the maximum energy M interacting with Wien-type N(k {sub 0}){proportional_to}k{sup q} {sub 0}exp (- k {sub 0}/{Theta}) soft photon distributions with total number density N {sub 0}, we calculate analytical approximations for the electron production spectrum. For distant objects with luminosity distances d{sub L} >> r {sub 0} = ({sigma} {sub T} N {sub 0}){sup -1} = 0.49N {sup -1} {sub 0} Mpc (with Thomson cross section {sigma} {sub T}), the implied large values of the optical depth {tau}{sub 0} = d{sub L} /r {sub 0} indicate that the electron production spectra differ at energies inside and outside the interval [({Theta}ln {tau}{sub 0}){sup -1}, {tau}{sub 0}/{Theta}], given the maximum gamma-ray energy M >> {Theta}{sup -1}. In the case M >> {Theta}{sup -1}, the production spectrum is strongly peaked near E {approx_equal} {Theta}{sup -1}, being exponentially reduced at small energies and decreasing with the steep power law {proportional_to}E {sup -1-p} up to the maximum energy E = M - (1/2).
19. Charmonium production in ultra-peripheral heavy ion collisions with two-photon processes
Yu, Gong-Ming; Yu, Yue-Chao; Li, Yun-De; Wang, Jian-Song
2017-04-01
We calculate the production of large-pT charmonium and narrow resonance state (exotic charmonium) in proton-proton, proton-nucleus, and nucleus-nucleus collisions with the semi-coherent two-photon interactions at Relativistic Heavy Ion Collider (RHIC), Large Hadron Collider (LHC), and Future Circular Collider (FCC) energies. Using the large quasi-real photon fluxes, we present the γγ → H differential cross section for charmonium and narrow resonance state production at large transverse momentum in ultra-peripheral heavy ion collisions. The numerical results demonstrate that the experimental study of ultra-peripheral collisions is feasible at RHIC, LHC, and FCC energies.
20. The two-photon excitation cross section of 6MAP, a fluorescent adenine analogue.
PubMed
Stanley, Robert J; Hou, Zhanjia; Yang, Aiping; Hawkins, Mary E
2005-03-03
6MAP is a fluorescent analogue of adenine that undergoes Watson-Crick base pairing and base stacking in double-stranded DNA. The one-photon absorption spectrum of 6MAP is characterized by a maximum around 330 nm with moderate quantum yield fluorescence centered at about 420 nm. To take advantage of this probe for confocal and single-molecule microscopy, it would be advantageous to be able to excite the analogue via two photons. We report the first determination of the two-photon excitation cross section and spectrum for 6MAP from 614 to 700 nm. The power dependence of the fluorescence indicates that emission results from the absorption of two photons. The one-photon and two-photon emission line shapes are identical within experimental error. A study of the concentration dependence of the fluorescence yield for one-photon excitation shows no measurable quenching up to about 5 microM. The maximum in the two-photon excitation spectrum gives a two-photon cross section, delta(TPE), of 3.4 +/- 0.1 Goeppert-Mayer (G.M.) at 659 nm, which correlates well with the one-photon absorption maximum. This compares quite favorably with cross sections of various naturally fluorescent biological molecules such as flavins and nicotiamide. In addition, we have also obtained the two-photon-induced fluorescence emission spectrum of quinine sulfate. It is approximately the same as that for one-photon excitation, suggesting that two-photon excitation of quinine sulfate may be used for calibration purposes.
1. Two-dimensional two-photon absorbing chromophores and solvent effects on their cross-sections
Zheng, Lixin; Jen, Alex K.
2003-02-01
A series of 2-dimensional two-photon absorbing chromophores and their 1-dimensional analogs were studied. The influence of the solvents on the linear absorption, photoluminescence and two-photon absorption cross-sections were also examined for these chromophores. The stoke's shift increase with increasing solvent polarity, that can be adequately described by Lippert equation. Two-photon absorption cross sections were measured with femtosecond pulses by the two-photon-induced fluorescence technique. It was observed that two-photon cross-sections were also strongly dependent on the solvents, however no simple correlation with solvent polarity was found in this study. Interestingly, a linear relationship was observed in these chromophores between the molar extinction coefficient and the two-photon cross section when plotted in log-log formats. Understanding of the relationship may provide a better insight of the two-photon absorption processes, and potentially will contribute to the design of highly efficient two-photon absorbing chromophores.
2. Geometric effect on photonic nanojet generated by dielectric microcylinders with non-cylindrical cross-sections
Liu, Cheng-Yang; Lin, Fan-Chih
2016-12-01
We experimentally report the geometric effect on photonic nanojet generated by dielectric microcylinders with non-cylindrical cross-sections. The non-cylindrical cross-sections include truncated microcylinders and elliptical microcylinders. The truncated microcylinder is formed with the cutting thickness. The elliptical microcylinder is defined by ratio of minor to major axes. The specific spatial electromagnetic fields for microcylinders with different non-cylindrical cross-sections are studied by using finite-difference time-domain calculation. The direct imaging of photonic nanojets for microcylinders with different non-cylindrical cross-sections are performed with a scanning optical microscope system. The field distribution and location of photonic nanojet depending on the various spatial shapes are experimentally demonstrated. The photonic nanojet with long focal length and low divergence could be used to scan over a target to obtain a large area image when the non-cylindrical micro-media are coupled with a conventional optical microscope.
3. Universal Parametrization of Thermal Photon Production in Hadronic Matter
Heffernan, Matthew; Hohler, Paul; Rapp, Ralf
2014-09-01
As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of thermal photon production largely within an unprecedented 20% of the calculated values from the spectral function, a significant reduction in error from available parametrizations. The contribution of photons and dileptons from pion-pion bremsstrahlung is evaluated for the importance of its contribution. The functional form, coupled with the comparison to the bremsstrahlung production of thermal photons, will provide a baseline for guiding future studies. As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of
4. Study of $π0$ pair production in single-tag two-photon collisions
SciTech Connect
Masuda, M.; Uehara, S.; Watanabe, Y.; Nakazawa, H.; Abdesselam, A.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Babu, V.; Badhrees, I.; Bakich, A. M.; Barberio, E.; Behera, P.; Bhuyan, B.; Biswal, J.; Bobrov, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Browder, T. E.; Červenkov, D.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Chistov, R.; Cho, K.; Chobanova, V.; Choi, S. -K.; Choi, Y.; Cinabro, D.; Dalseno, J.; Danilov, M.; Dash, N.; Dingfelder, J.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gillard, R.; Giordano, F.; Glattauer, R.; Goh, Y. M.; Goldenzweig, P.; Golob, B.; Haba, J.; Hayasaka, K.; Hayashii, H.; He, X. H.; Hou, W. -S.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Jaegle, I.; Joffe, D.; Joo, K. K.; Julius, T.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kim, D. Y.; Kim, J. B.; Kim, J. H.; Kim, K. T.; Kim, M. J.; Kim, S. H.; Kim, Y. J.; Ko, B. R.; Korpar, S.; Križan, P.; Krokovny, P.; Kumita, T.; Kuzmin, A.; Kwon, Y. -J.; Lange, J. S.; Lee, D. H.; Lee, I. S.; Li, C.; Li, L.; Li, Y.; Libby, J.; Liventsev, D.; Lukin, P.; Matvienko, D.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Mohanty, S.; Moll, A.; Moon, H. K.; Mori, T.; Mussa, R.; Nakano, E.; Nakao, M.; Nanut, T.; Natkaniec, Z.; Nayak, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Park, C. W.; Park, H.; Pedlar, T. K.; Pestotnik, R.; Petrič, M.; Piilonen, L. E.; Rauch, J.; Ribežl, E.; Ritter, M.; Rostomyan, A.; Sandilya, S.; Santelj, L.; Sanuki, T.; Sato, Y.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seino, Y.; Senyo, K.; Seon, O.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T. -A.; Shiu, J. -G.; Shwartz, B.; Simon, F.; Sohn, Y. -S.; Sokolov, A.; Solovieva, E.; Starič, M.; Sumihama, M.; Sumiyoshi, T.; Tamponi, U.; Tanida, K.; Teramoto, Y.; Uglov, T.; Unno, Y.; Uno, S.; Van Hulse, C.; Vanhoefer, P.; Varner, G.; Vinokurova, A.; Vorobyev, V.; Vossen, A.; Wagner, M. N.; Wang, C. H.; Wang, M. -Z.; Wang, P.; Williams, K. M.; Won, E.; Yamaoka, J.; Yamashita, Y.; Yashchenko, S.; Ye, H.; Yusa, Y.; Zhang, C. C.; Zhang, Z. P.; Zhilich, V.; Zhulanov, V.; Zupanc, A.
2016-02-01
We report a measurement of the differential cross section of π^0 pair production in single-tag two-photon collisions, y*y->π^0π^0, in e+e- scattering. The cross section is measured for Q^2up to 30 GeV^2 is the negative of the invariant mass squared of the tagged photon
5. Prompt photon production in p-p collisions
SciTech Connect
Cleymans, J.; Quack, E.; Redlich, K.
1995-07-01
A systematic study of the inclusive photon cross-section in p-p collisions is presented. The dependence of the {gamma} rates on the renormalization and factorization scales is discussed. A comparison is made with experimental data for centre-of-mass energies ranging from 23 GeV to 1.8 TeV. Predictions of the cross-sections are given for two different sets of structure functions for RHIC and LHC energies.
Kaufmann, Tom; Mukherjee, Asmita; Vogelsang, Werner
2016-06-01
We argue that the process p p →(jet γ )X , for which a photon is observed inside a fully reconstructed jet and is treated as part of the jet, offers new probes of the so far little-known fragmentation functions for photons. We present a next-to-leading-order QCD calculation of the cross section for this process in the limit that the jet is relatively narrow. We also investigate the background resulting from the two-photon decay of neutral pions. We present numerical results relevant for possible measurements at the LHC and at RHIC. These suggest that p p →(jet γ )X should provide clean access to the photon fragmentation functions, provided an efficient suppression of the background is available in experiment.
7. Hard thermal photon production in relativistic heavy ion collisions
Steffen, F. D.; Thoma, M. H.
2001-06-01
The recent status of hard thermal photon production in relativistic heavy ion collisions is reviewed and the current rates are presented with emphasis on corrected bremsstrahlung processes in the quark-gluon plasma (QGP) and quark-hadron duality. Employing Bjorken hydrodynamics with an EOS supporting the phase transition from QGP to hot hadron gas (HHG), thermal photon spectra are computed. For SPS 158 GeV Pb+Pb collisions, comparison with other theoretical results and the WA98 direct photon data indicates significant contributions due to prompt photons. Extrapolating the presented approach to RHIC and LHC experiments, predictions of the thermal photon spectrum show a QGP outshining the HHG in the high-pT-region.
8. Coherent destruction of tunneling in two-level system driven across avoided crossing via photon statistics.
PubMed
Miao, Qiang; Zheng, Yujun
2016-06-29
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons 〈N〉 and the Mandel's Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel's Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
9. Coherent destruction of tunneling in two-level system driven across avoided crossing via photon statistics
PubMed Central
Miao, Qiang; Zheng, Yujun
2016-01-01
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons 〈N〉 and the Mandel’s Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel’s Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively. PMID:27353375
10. Coherent destruction of tunneling in two-level system driven across avoided crossing via photon statistics
Miao, Qiang; Zheng, Yujun
2016-06-01
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons and the Mandel’s Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel’s Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
11. Off-equilibrium photon production during the chiral phase transition
SciTech Connect
Michler, Frank; Hees, Hendrik van; Dietrich, Dennis D.; Leupold, Stefan; Greiner, Carsten
2013-09-15
In the early stage of ultrarelativistic heavy-ion collisions chiral symmetry is restored temporarily. During this so-called chiral phase transition, the quark masses change from their constituent to their bare values. This mass shift leads to the spontaneous non-perturbative creation of quark–antiquark pairs, which effectively contributes to the formation of the quark–gluon plasma. We investigate the photon production induced by this creation process. We provide an approach that eliminates possible unphysical contributions from the vacuum polarization and renders the resulting photon spectra integrable in the ultraviolet domain. The off-equilibrium photon numbers are of quadratic order in the perturbative coupling constants while a thermal production is only of quartic order. Quantitatively, we find, however, that for the most physical mass-shift scenarios and for photon momenta larger than 1 GeV the off-equilibrium processes contribute less photons than the thermal processes. -- Highlights: •We investigate first-order photon emission arising from the chiral mass shift. •We provide an ansatz eliminating possible unphysical vacuum contributions. •Our ansatz leads to photon spectra being integrable in the ultraviolet domain.
12. Benchmark cross sections for bottom quark production
SciTech Connect
Berger, E.L.
1988-01-07
A summary is presented of theoretical expectations for the total cross sections for bottom quark production, for longitudinal and transverse momentum distributions, and for b, /bar b/ momentum correlations at Fermilab fixed target and collider energies.
13. Phenomenology of photon and dilepton production in relativistic nuclear collisions
Bratkovskaya, Elena
2014-11-01
We discuss the latest theoretical results on direct photon and dilepton production from relativistic heavy-ion collisions. While the dilepton spectra at low invariant mass show in-medium effects like collisional broadening of the vector meson spectral functions, the dilepton yield at high invariant masses (above 1.1 GeV) is dominated by QGP contributions for central heavy-ion collisions at relativistic energies. The present status of the photon v2 "puzzle" - a large elliptic flow v2 of the direct photons experimentally observed at RHIC and LHC energies - is also addressed. The role of hadronic and partonic sources for the photon spectra and v2 is considered as well as the possibility to subtract the QGP signal from the experimental observables.
14. Isolated Photon Cross Section in pp¯ Collisions at √s = 1.8 TeV
Abbott, B.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Ahn, S.; Akimov, V.; Alves, G. A.; Amos, N.; Anderson, E. W.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Baden, A.; Baldin, B.; Banerjee, S.; Bantly, J.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Chen, W.; Cho, D. K.; Choi, S.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Cullen-Vidal, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Denisov, D.; Denisov, S. P.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Draper, P.; Ducros, Y.; Dudko, L. V.; Dugad, S. R.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gibbard, B.; Gilmartin, R.; Ginther, G.; Gobbi, B.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J. A.; Greenlee, H.; Grinstein, S.; Grudberg, P.; Grünendahl, S.; Guglielmo, G.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Ito, A. S.; Jerger, S. A.; Jesik, R.; Joffe-Minor, T.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Jun, S. Y.; Kahn, S.; Kajfasz, E.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Kim, S. K.; Klima, B.; Klopfenstein, C.; Knuteson, B.; Ko, W.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Landsberg, G.; Leflat, A.; Lehner, F.; Li, J.; Li, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lu, J. G.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Maciel, A. K.; Madaras, R. J.; Manankov, V.; Mani, S.; Mao, H. S.; Markeloff, R.; Marshall, T.; Martin, M. I.; Martin, R. D.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McKibben, T.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Negret, J. P.; Negroni, S.; Norman, D.; Oesch, L.; Oguri, V.; Olivier, B.; Oshima, N.; Owen, D.; Padley, P.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, M.; Piegaia, R.; Piekarz, H.; Pischalnikov, Y.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Reay, N. W.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sculli, J.; Sen, N.; Shabalina, E.; Shankar, H. C.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Song, X. F.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stevenson, M. L.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stoyanova, D. A.; Strauss, M.; Streets, K.; Strovink, M.; Stutte, L.; Sznajder, A.; Tarazi, J.; Tartaglia, M.; Thomas, T. L.; Thompson, J.; Toback, D.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; van Gemmeren, P.; Vaniev, V.; Varelas, N.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Wightman, J. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Wood, D. R.; Yamada, R.; Yamin, P.; Yasuda, T.; Yip, K.; Youssef, S.; Yu, J.; Yu, Y.; Zanabria, M.; Zheng, H.; Zhou, Z.; Zhu, Z. H.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.
2000-03-01
We report a new measurement of the cross section for the production of isolated photons with transverse energies ( EγT) above 10 GeV and pseudorapidities \\|η\\|<2.5 in pp¯ collisions at s = 1.8 TeV. The results are based on a data sample of 107.6 pb-1 recorded during 1992-1995 with the D0 detector at the Fermilab Tevatron collider. The background, predominantly from jets which fragment to neutral mesons, was estimated using the longitudinal shower shape of photon candidates in the calorimeter. The measured cross section is in good agreement with the next-to-leading order QCD calculation for EγT>~36 GeV.
15. Measurement of Two-Photon Absorption Cross Section of Metal Ions by a Mass Sedimentation Approach
PubMed Central
Ma, Zhuo-Chen; Chen, Qi-Dai; Han, Bing; Liu, Xue-Qing; Song, Jun-Feng; Sun, Hong-Bo
2015-01-01
The photo-reduction of metal ions in solution induced by femtosecond laser is an important and novel method for fabricating three-dimensional metal microstructures. However, the nonlinear absorption cross section of metal ions remains unknown because its measurement is difficult. In the present study, a method based on Two-Photon Excited Sedimentation (TPES) is proposed to measure the two-photon absorption cross section (TPACS) of metal ions in solution. The power-squared dependence of the amount of sediment on the excitation intensity was confirmed, revealing that 800 nm femtosecond laser induced reduction of metal ions was a two photon absorption process. We believe that the proposed method may be applied to measure the TPACS of several metal ions, thereby opening a new avenue towards future analysis of two-photon absorption materials. PMID:26657990
16. Photon scattering cross sections of H2 and He measured with synchrotron radiation
NASA Technical Reports Server (NTRS)
Ice, G. E.
1977-01-01
Total (elastic + inelastic) differential photon scattering cross sections have been measured for H2 gas and He, using an X-ray beam. Absolute measured cross sections agree with theory within the probable errors. Relative cross sections (normalized to theory at large S) agree to better than one percent with theoretical values calculated from wave functions that include the effect of electron-electron Coulomb correlation, but the data deviate significantly from theoretical independent-particle (e.g., Hartree-Fock) results. The ratios of measured absolute He cross sections to those of H2, at any given S, also agree to better than one percent with theoretical He-to-H2 cross-section ratios computed from correlated wave functions. It appears that photon scattering constitutes a very promising tool for probing electron correlation in light atoms and molecules.
17. Improved calculation of total cross section for pair production by relativistic heavy ions
NASA Technical Reports Server (NTRS)
Eby, P. B.
1989-01-01
A calculation of the total cross section for direct electron-positron pair production by heavy ions is described. It combines the use of the Weizsaecker-Williams method for low-energy transfers and existing calculations for high-energy transfers. Higher-order corrections to the total cross section are calculated based on the Weizsaecher-Williams method and existing results for pair production by photons.
18. Measurement of the inclusive isolated prompt photon cross-section in pp collisions at √{ s} = 7 TeV using 35pb-1 of ATLAS data
2011-12-01
A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy √{ s} = 7 TeV is presented. The measurement covers the pseudorapidity ranges | η | < 1.37 and 1.52 ⩽ | η | < 2.37 in the transverse energy range 45 ⩽ET < 400 GeV. The results are based on an integrated luminosity of 35pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.
19. Consistency of data on soft photon production in hadronic interactions
SciTech Connect
Lichard, P. )
1994-12-01
The glob model of Lichard and Van Hove and the modified soft annihilation model (MSAM) of Lichard and Thompson are used as a phenomenological tool for relating results from various experiments on soft photon production in high energy collisions. The total phenomenological expectation is composed of contributions from classical bremsstrahlung, the soft annihilation model, and the glob model. The empirical excess above the background from hadronic decays at very small longitudinal momenta of photons is well reproduced, as well as that for transverse momenta [ital p][sub [ital T
20. Heavy Meson Production at a Low-Energy Photon Collider
SciTech Connect
Asztalos, S
2004-04-15
A low-energy {gamma}{gamma} collider has been discussed in the context of a testbed for a {gamma}{gamma} interaction region at the Next Linear Collider(NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual {gamma}{gamma} luminosities.
1. Cross sections for non-sequential two-photon double ionization of helium
Feist, Johannes; Nagele, Stefan; Pazourek, Renate; Persson, Emil; Burgdörfer, Joachim; Schneider, Barry; Collins, Lee
2008-05-01
The generalized cross sections for non-sequential two-photon double ionization of helium at photon energies from 39.5,V to 54.4,V have been the subject of several recent theoretical studies. Quantitative agreement between the different approaches has not yet been reached. In this contribution, we present converged results for the total integrated and triply differential cross sections for the above process, which are based on the direct integration of the time-dependent Schr"odinger equation. We compare our data with calculations from other authors and investigate to what extent electronic correlation in the representation of the double continuum affects the cross sections. We also study the influence of the pulse shape on the value of the cross sections extracted from time-dependent approaches.
2. Photon-exposure-dependent photon-stimulated desorption for obtaining photolysis cross section of molecules adsorbed on surface by monochromatic soft x-ray photons.
PubMed
Chou, L-C; Jang, C-Y; Wu, Y-H; Tsai, W-C; Wang, S-K; Chen, J; Chang, S-C; Liu, C-C; Shai, Y; Wen, C-R
2008-12-07
Photon-exposure-dependent positive- and negative-ion photon-stimulated desorption (PSD) was proposed to study the photoreactions and obtain the photolysis cross sections of molecules adsorbed on a single-crystal surface by monochromatic soft x-ray photons with energy near the core level of adsorbate. The changes in the F(+) and F(-) PSD ion yields were measured from CF(3)Cl molecules adsorbed on Si(111)-7x7 at 30 K (CF(3)Cl dose=0.3x10(15) molecules/cm(2), approximately 0.75 monolayer) during irradiation of monochromatic soft x-ray photons near the F(1s) edge. The PSD ion yield data show the following characteristics: (a) The dissociation of adsorbed CF(3)Cl molecules is due to a combination of direct photodissociation via excitation of F(1s) core level and substrate-mediated dissociation [dissociative attachment and dipolar dissociation induced by the photoelectrons emitting from the silicon substrate]. (b) the F(+) ion desorption is associated with the bond breaking of the surface CF(3)Cl, CF(2)Cl, CFCl, and SiF species. (c) the F(-) yield is mainly due to DA and DD of the adsorbed CF(3)Cl molecules. (d) The surface SiF is formed by reaction of the surface Si atom with the neutral fluorine atom, F(+), or F(-) ion produced by scission of C-F bond of CF(3)Cl, CF(2)Cl, or CFCl species. A kinetic model was proposed for the explanation of the photolysis of this submonolayer CF(3)Cl-covered surface. Based on this model and the variation rates of the F(+)F(-) signals during fixed-energy monochromatic photon bombardment at 690.2 and 692.6 eV [near the F(1s) edge], the photolysis cross section was deduced as a function of energy.
3. Quantum teleportation of a generic two-photon state with weak cross-Kerr nonlinearities
Wang, Meiyu; Yan, Fengli
2016-08-01
We present a scheme for teleporting a generic two-photon polarization state by using two EPR states as quantum channel based on weak cross-Kerr nonlinearities. As the core component of the present framework, the quantum nondemolition detector based on the weak cross-Kerr nonlinearity acts as an EPR entangler as well as the Bell-state analyzer. This makes the teleportation protocol be achieved near deterministically and be feasible in the current experimental technology.
4. Generation of four-photon polarization entangled decoherence-free states with cross-Kerr nonlinearity
PubMed Central
Wang, Meiyu; Yan, Fengli; Gao, Ting
2016-01-01
We propose a theoretical protocol for preparing four-photon polarization entangled decoherence-free states, which are immune to the collective noise. With the assistance of the cross-Kerr nonlinearities, a two-photon spatial entanglement gate, two controlled-NOT gates, a four-photon polarization entanglement gate are inserted into the circuit, where X homodyne measurements are aptly applied. Combined with some swap gates and simple linear optical elements, four-photon polarization entangled decoherence-free states which can be utilized to represent two logical qubits, |0〉L and |1〉L are achieved at the output ports of the circuit. This generation scheme may be implemented with current experimental techniques. PMID:27901116
5. Atlas of photoneutron cross sections obtained with monoenergetic photons. Final edition, 1986
SciTech Connect
Dietrich, S.S.; Berman, B.L.
1986-06-01
In view of the need for a comprehensive compilation of photoneutron cross-section data, these monoenergetic-photon data are gathered together here and presented in a uniform format. This compilation updates and supersedes the earlier editions of this Atlas. A more complete compilation is being assembled by the photonuclear group at the National Bureau of Standards. 15 refs., 174 figs.
6. Probing gluon saturation with next-to-leading order photon production at central rapidities in proton-nucleus collisions
Benić, Sanjin; Fukushima, Kenji; Garcia-Montero, Oscar; Venugopalan, Raju
2017-01-01
We compute the cross section for photons emitted from sea quarks in proton-nucleus collisions at collider energies. The computation is performed within the dilute-dense kinematics of the Color Glass Condensate (CGC) effective field theory. Albeit the result obtained is formally at next-to-leading order in the CGC power counting, it provides the dominant contribution for central rapidities. We observe that the inclusive photon cross section is proportional to all-twist Wilson line correlators in the nucleus. These correlators also appear in quark-pair production; unlike the latter, photon production is insensitive to hadronization uncertainties and therefore more sensitive to multi-parton correlations in the gluon saturation regime of QCD. We demonstrate that k ⊥ and collinear factorized expressions for inclusive photon production are obtained as leading twist approximations to our result. In particular, the collinearly factorized expression is directly sensitive to the nuclear gluon distribution at small x. Other results of interest include the realization of the Low-Burnett-Kroll soft photon theorem in the CGC framework and a comparative study of how the photon amplitude is obtained in Lorenz and light-cone gauges.
7. Higgs boson pair production in new physics models at hadron, lepton, and photon colliders
SciTech Connect
2010-12-01
We study Higgs boson pair production processes at future hadron and lepton colliders including the photon collision option in several new physics models; i.e., the two-Higgs-doublet model, the scalar leptoquark model, the sequential fourth generation fermion model and the vectorlike quark model. Cross sections for these processes can deviate significantly from the standard model predictions due to the one-loop correction to the triple Higgs boson coupling constant. For the one-loop induced processes such as gg{yields}hh and {gamma}{gamma}{yields}hh, where h is the (lightest) Higgs boson and g and {gamma} respectively represent a gluon and a photon, the cross sections can also be affected by new physics particles via additional one-loop diagrams. In the two-Higgs-doublet model and scalar leptoquark models, cross sections of e{sup +}e{sup -}{yields}hhZ and {gamma}{gamma}{yields}hh can be enhanced due to the nondecoupling effect in the one-loop corrections to the triple Higgs boson coupling constant. In the sequential fourth generation fermion model, the cross section for gg{yields}hh becomes very large because of the loop effect of the fermions. In the vectorlike quark model, effects are small because the theory has decoupling property. Measurements of the Higgs boson pair production processes can be useful to explore new physics through the determination of the Higgs potential.
8. Consistent simulation of direct-photon production in hadron collisions including associated two-jet production
Odaka, Shigeru; Kurihara, Yoshimasa
2016-05-01
We have developed an event generator for direct-photon production in hadron collisions, including associated 2-jet production in the framework of the GR@PPA event generator. The event generator consistently combines γ + 2-jet production processes with the lowest-order γ + jet and photon-radiation (fragmentation) processes from quantum chromodynamics (QCD) 2-jet production using a subtraction method. The generated events can be fed to general-purpose event generators to facilitate the addition of hadronization and decay simulations. Using the obtained event information, we can simulate photon isolation and hadron-jet reconstruction at the particle (hadron) level. The simulation reasonably reproduces measurement data obtained at the large hadron collider (LHC) concerning not only the inclusive photon spectrum, but also the correlation between the photon and jet. The simulation implies that the contribution of the γ + 2-jet is very large, especially in low photon-pT ( ≲ 50 GeV) regions. Discrepancies observed at low pT, although marginal, may indicate the necessity for the consideration of further higher-order processes. Unambiguous particle-level definition of the photon-isolation condition for the signal events is desired to be given explicitly in future measurements.
9. Measurement of the two-photon absorption cross section by means of femtosecond thermal lensing.
PubMed
Rodriguez, Luis; Chiesa, Matteo
2011-07-01
We present a variation of the single-beam thermal lensing experiment to determine the two-photon absorption cross sections of classical fluorophores. The approach is based on comparison of two thermal lensing signals simultaneously induced by a one- and two-photon absorption process from a high-repetition-rate femtosecond laser system. As a consequence of this comparison, a simplified expression independent of the several experimental parameters is obtained. Additionally, because of the low incident power levels required, undesirable optical effects such as Kerr or Raman scattering are avoided. Our experimental results agree well with those recently published for luminescent methods, validating the approach.
10. Generation of four-photon polarization entangled states with cross-Kerr nonlinearity
Wang, Meiyu; Yan, Fengli
2015-05-01
We show how to prepare three different types of four-photon polarization entangled states among four modes. The scheme only use cross-Kerr medium, polarization beam splitters and X homodyne measurements on coherent light fields, which can be efficiently implemented in quantum optical laboratories. GHZ states and symmetric Dick states can be generated in deterministic way based on the scheme. With the possible availability of suitable strong Kerr nonlinearity, another type of entangled state called genuine four-photon entangled state can be realized as well.
11. Cross-phase-modulation-induced instability in photonic-crystal fibers.
PubMed
Serebryannikov, E E; Konorov, S O; Ivanov, A A; Alfimov, M V; Scalora, M; Zheltikov, A M
2005-08-01
Cross-phase-modulation-induced instability is identified as a significant mechanism for efficient parametric four-wave-mixing frequency conversion in photonic-crystal fibers. Fundamental-wavelength femtosecond pulses of a Cr, forsterite laser are used in our experiments to transform the spectrum of copropagating second-harmonic pulses of the same laser in a photonic-crystal fiber. Efficient generation of sidebands shifted by more than 80 THz with respect to the central frequency of the second harmonic is observed in the output spectrum of the probe field.
12. Low-cost label-free biosensors using photonic crystals embedded between crossed polarizers.
PubMed
Nazirizadeh, Yousef; Bog, Uwe; Sekula, Sylwia; Mappes, Timo; Lemmer, Uli; Gerken, Martina
2010-08-30
There is a strong need for low-cost biosensors to enable rapid, on-site analysis of biological, biomedical, or chemical substances. We propose a platform for label-free optical biosensors based on applying the analyte onto a surface-functionalized photonic crystal slab and performing a transmission measurement with two crossed polarization filters. This dark-field approach allows for efficient background suppression as only the photonic crystal guided-mode resonances interacting with the functionalized surface experience significant polarization rotation. We present a compact biosensor demonstrator using a low-cost light emitting diode and a simple photodiode capable of detecting the binding kinetics of a 2.5 nM solution of the protein streptavidin on a biotin-functionalized photonic crystal surface.
13. Momentum imbalance of isolated photon-tagged jet production at RHIC and LHC.
PubMed
Dai, Wei; Vitev, Ivan; Zhang, Ben-Wei
2013-04-05
In collisions of ultrarelativistic nuclei, photon-tagged jets provide a unique opportunity to compare jet production and modification due to parton shower formation and propagation in strongly interacting matter at vastly different center-of-mass energies. We present first results for the cross sections of jets tagged by an isolated photon to O(α(em)α(s)(2)) in central Au+Au reactions with sqrt[s(NN)] = 200 GeV at RHIC and central Pb + Pb reactions with sqrt[s(NN)] = 2.76 TeV at LHC. We evaluate the increase in the transverse momentum imbalance of the observed γ + jet state, induced by the dissipation of the parton shower energy due to strong final-state interactions. Theoretical predictions to help interpret recent and upcoming experimental data are presented.
14. Deterministic reshaping of single-photon spectra using cross-phase modulation
PubMed Central
2016-01-01
The frequency conversion of light has proved to be a crucial technology for communication, spectroscopy, imaging, and signal processing. In the quantum regime, it also offers great potential for realizing quantum networks incorporating disparate physical systems and quantum-enhanced information processing over a large computational space. The frequency conversion of quantum light, such as single photons, has been extensively investigated for the last two decades using all-optical frequency mixing, with the ultimate goal of realizing lossless and noiseless conversion. I demonstrate another route to this target using frequency conversion induced by cross-phase modulation in a dispersion-managed photonic crystal fiber. Owing to the deterministic and all-optical nature of the process, the lossless and low-noise spectral reshaping of a single-photon wave packet in the telecommunication band has been readily achieved with a modulation bandwidth as large as 0.4 THz. I further demonstrate that the scheme is applicable to manipulations of a nonclassical frequency correlation, wave packet interference, and entanglement between two photons. This approach presents a new coherent frequency interface for photons for quantum information processing. PMID:27051862
15. Vector meson and associated strangeness production using a linearly polarized photon beam at Jefferson Lab
SciTech Connect
Philip L. Cole
2004-09-01
The set of experiments forming the g8a run took place in the summer of 2001 in Hall B of Jefferson Lab. The g8a run was the commissioning experiment for the linearly-polarized photon beam at CLAS. The aim of these experiments is to improve the understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. A beam of tagged and collimated linearly polarized photons (energy range 1.8-2.2 GeV) in conjunction with the large solid angle coverage of CLAS make possible the extraction of the differential cross-sections and polarization observables for the photoproduction of vector mesons and kaons. The reaction channels are under investigation to search for possibly missing nucleon resonances. An overview of the experiment and preliminary results on the measurement of the photon asymmetries of the aforementioned reactions will be presented in this paper.
16. Exclusive production of pion and kaon meson pairs in two photon collisions at LEP
ALEPH Collaboration; Heister, A.; Schael, S.; Barate, R.; Brunelière, R.; de Bonis, I.; Decamp, D.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocmé, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmüller, O.; Cattaneo, M.; Clerbaux, B.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Hansen, J. B.; Harvey, J.; Hutchcroft, D. E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Sguazzoni, G.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J. M.; Perret, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Kraan, A. C.; Nilsson, B. S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G. P.; Passalacqua, L.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Thompson, A. S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P. J.; Girone, M.; Hill, R. D.; Marinelli, N.; Nowell, J.; Rutherford, S. A.; Sedgbeer, J. K.; Thompson, J. C.; White, R.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Clarke, D. P.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Smizanska, M.; van der Aa, O.; Delaere, C.; Leibenguth, G.; Lemaitre, V.; Blumenschein, U.; Hölldorfer, F.; Jakobs, K.; Kayser, F.; Kleinknecht, K.; Müller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Männer, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Awunor, O.; Blair, G. A.; Cowan, G.; Garcia-Bellido, A.; Green, M. G.; Jones, L. T.; Medcalf, T.; Misiejuk, A.; Strong, J. A.; Teixeira-Dias, P.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Ward, J. J.; Bloch-Devaux, B.; Boumediene, D.; Colas, P.; Fabbro, B.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, B.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S. R.; Berkelman, K.; Cranmer, K.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A.; Nielsen, J.; Pan, Y. B.; von Wimmersperg-Toeller, J. H.; Wiedenmann, W.; Wu, J.; Wu, S. L.; Wu, X.; Zobernig, G.; Dissertori, G.
2003-09-01
Exclusive production of /π and K meson pairs in two photon collisions is measured with ALEPH data collected between 1992 and 2000. Cross-sections are presented as a function of cosθ* and invariant mass, for cosθ*<0.6 and invariant masses between 2.0 and 6.0 GeV/c2 (2.25 and 4.0 GeV/c2) for pions (kaons). The shape of the distributions are found to be well described by QCD predictions but the data have a significantly higher normalization.
17. A phenomenological study of photon production in low energy neutrino nucleon scattering
SciTech Connect
Jenkins, James P; Goldman, Terry J
2009-01-01
Low energy photon production is an important background to many current and future precision neutrino experiments. We present a phenomenological study of t-channel radiative corrections to neutral current neutrino nucleus scattering. After introducing the relevant processes and phenomenological coupling constants, we will explore the derived energy and angular distributions as well as total cross-section predictions along with their estimated uncertainties. This is supplemented throughout with comments on possible experimental signatures and implications. We conclude with a general discussion of the analysis in the context of complimentary methodologies. This is based on a talk presented at the DPF 2009 meeting in Detroit MI.
18. Inclusive J/psi production in two-photon collisions at LEP II with the DELPHI detector
Chapkine, Mikhail
2002-06-01
Inclusive J/psi production in photon-photon collisions has been observed by the DELPHI collaboration at LEP II beam energies. A clean signal from the reaction gamma][gamma [right arrow] J/psi + X is seen. Number of observed events, N(J/psi [right arrow] mu]+[mu-) = 36 plus-or-minus 7 for the integrated luminosity 617 pb-1, yielding a cross section of sigma](J/[psi [right arrow] mu]+[mu-) = 25.2 plus-or-minus 10.2 pb. Based on a study of the event shapes of different types of gamma][gamma processes in the PYTHIA program, we conclude that (74plus-or-minus22)% of the observed J/psi events are due to the 'resolved' photons, the dominant contribution of which is evidently a single color-octet gluon within the photon.
19. Study of inclusive J/ψ production in two-photon collisions at LEP II with the DELPHI detector
Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alderweireld, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Almehed, S.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Bellunato, T.; Belous, K.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Bugge, L.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Carimalo, C.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crawley, B.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Dris, M.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gele, D.; Geralis, T.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hahn, F.; Hahn, S.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Hansen, J.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Hultqvist, K.; Jackson, J. N.; Jarlskog, Ch.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Keranen, R.; Kernel, G.; Kersevan, B. P.; Kiiskinen, A.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Kurowska, J.; Laforge, B.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Meyer, W. T.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nemecek, S.; Nicolaidou, R.; Niezurawski, P.; Nikolenko, M.; Nygren, A.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Rames, J.; Ramler, L.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Ripp-Baudot, I.; Rodriguez, D.; Romero, A.; Ronchese, P.; Rosenberg, E.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Savoy-Navarro, A.; Schwanda, C.; Schwering, B.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Terranova, F.; Timmermans, J.; Tinti, N.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Ullaland, O.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Lysebetten, A.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verbeure, F.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zimin, N. I.; Zintchenko, A.; Zoller, Ph.; Zupan, M.; Delphi Collaboration
2003-07-01
Inclusive J/ψ production in photon-photon collisions has been observed at LEP II beam energies. A clear signal from the reaction γγ→J/ψ+X is seen. The number of observed N(J/ψ→μ+μ-) events is 36±7 for an integrated luminosity of 617 pb-1, yielding a cross-section of σ(J/ψ+X)=45±9(stat)±17(syst) pb. Based on a study of the event shapes of different types of γγ processes in the PYTHIA program, we conclude that (74±22)% of the observed J/ψ events are due to 'resolved' photons, the dominant contribution of which is most probably due to the gluon content of the photon.
20. Study of inclusive /J/ψ production in two-photon collisions at LEP II with the DELPHI detector
DELPHI Collaboration; Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alderweireld, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Almehed, S.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Bellunato, T.; Belous, K.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Bugge, L.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Carimalo, C.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crawley, B.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Dris, M.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gele, D.; Geralis, T.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hahn, F.; Hahn, S.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Hansen, J.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Hultqvist, K.; Jackson, J. N.; Jarlskog, Ch.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Keranen, R.; Kernel, G.; Kersevan, B. P.; Kiiskinen, A.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Kurowska, J.; Laforge, B.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lenzen, G.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Meyer, W. T.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nemecek, S.; Nicolaidou, R.; Niezurawski, P.; Nikolenko, M.; Nygren, A.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Poropat, P.; Pozdniakov, V.; Privitera, P.; Pukhaeva, N.; Pullia, A.; Rames, J.; Ramler, L.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Ripp-Baudot, I.; Rodriguez, D.; Romero, A.; Ronchese, P.; Rosenberg, E.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Savoy-Navarro, A.; Schwanda, C.; Schwering, B.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Terranova, F.; Timmermans, J.; Tinti, N.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Ullaland, O.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Lysebetten, A.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verbeure, F.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zimin, N. I.; Zintchenko, A.; Zoller, Ph.; Zupan, M.
2003-07-01
Inclusive /J/ψ production in photon-photon collisions has been observed at LEP II beam energies. A clear signal from the reaction /γγ-->J/ψ+X is seen. The number of observed N(J/ψ-->μ+μ-) events is /36+/-7 for an integrated luminosity of 617 pb-1, yielding a cross-section of /σ(J/ψ+X)=45+/-9(stat)+/-17(syst) pb. Based on a study of the event shapes of different types of /γγ processes in the PYTHIA program, we conclude that /(74+/-22)% of the observed /J/ψ events are due to resolved' photons, the dominant contribution of which is most probably due to the gluon content of the photon.
1. Study of inclusive strange-baryon production and search for pentaquarks in two-photon collisions at LEP
Achard, P.; Adriani, O.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S. V.; Banerjee, S.; Banerjee, S.; Barczyk, A.; Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de La Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.; Deiters, K.; Della Volpe, D.; Delmeire, E.; Denes, P.; Denotaristefani, F.; de Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F. J.; Extermann, P.; Falagan, M. A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, P. H.; Fisher, W.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Y.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z. F.; Grenier, G.; Grimm, O.; Gruenewald, M. W.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Hervé, A.; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S. R.; Jin, B. N.; Jindal, P.; Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kaur, M.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Kopal, M.; Koutsenko, V.; Kräber, M.; Kraemer, R. W.; Krüger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J. M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W. G.; Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.; Muanza, G. S.; Muijs, A. J. M.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pieri, M.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Razis, P.; Rembeczki, S.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, K.; Roe, B. P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D. J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.; Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, S. C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Tully, C.; Tung, K. L.; Ulbricht, J.; Valente, E.; van de Walle, R. T.; Vasquez, R.; Vesztergombi, G.; Vetlitsky, I.; Viertel, G.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, Q.; Wang, X. L.; Wang, Z. M.; Weber, M.; Wynhoff, S.; Xia, L.; Xu, Z. Z.; Yamamoto, J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yeh, S. C.; Zalite, A.; Zalite, Y.; Zhang, Z. P.; Zhao, J.; Zhu, G. Y.; Zhu, R. Y.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zöller, M.
2007-01-01
Measurements of inclusive production of the Λ, Ξ- and Ξ*(1530) baryons in two-photon collisions with the L3 detector at LEP are presented. The inclusive differential cross sections for Λ and Ξ- are measured as a function of the baryon transverse momentum, pt, and pseudo-rapidity, η. The mean number of Λ, Ξ- and Ξ*(1530) baryons per hadronic two-photon event is determined in the kinematic range 0.4 GeVproduction of the pentaquark θ+(1540) in two-photon collisions through the decay θ+→pK0 S is also presented. No evidence for production of this state is found.
2. On two-parameter models of photon cross sections: application to dual-energy CT imaging.
PubMed
Williamson, Jeffrey F; Li, Sicong; Devic, Slobodan; Whiting, Bruce R; Lerma, Fritz A
2006-11-01
The goal of this study is to evaluate the theoretically achievable accuracy in estimating photon cross sections at low energies (20-1000 keV) from idealized dual-energy x-ray computed tomography (CT) images. Cross-section estimation from dual-energy measurements requires a model that can accurately represent photon cross sections of any biological material as a function of energy by specifying only two characteristic parameters of the underlying material, e.g., effective atomic number and density. This paper evaluates the accuracy of two commonly used two-parameter cross-section models for postprocessing idealized measurements derived from dual-energy CT images. The parametric fit model (PFM) accounts for electron-binding effects and photoelectric absorption by power functions in atomic number and energy and scattering by the Klein-Nishina cross section. The basis-vector model (BVM) assumes that attenuation coefficients of any biological substance can be approximated by a linear combination of mass attenuation coefficients of two dissimilar basis substances. Both PFM and BVM were fit to a modern cross-section library for a range of elements and mixtures representative of naturally occurring biological materials (Z = 2-20). The PFM model, in conjunction with the effective atomic number approximation, yields estimated the total linear cross-section estimates with mean absolute and maximum error ranges of 0.6%-2.2% and 1%-6%, respectively. The corresponding error ranges for BVM estimates were 0.02%-0.15% and 0.1%-0.5%. However, for photoelectric absorption frequency, the PFM absolute mean and maximum errors were 10.8%-22.4% and 29%-50%, compared with corresponding BVM errors of 0.4%-11.3% and 0.5%-17.0%, respectively. Both models were found to exhibit similar sensitivities to image-intensity measurement uncertainties. Of the two models, BVM is the most promising approach for realizing dual-energy CT cross-section measurement.
3. Entropy production in a lepton-photon universe
Husdal, Lars; Brevik, Iver
2017-02-01
We look at the entropy production during the lepton era in the early universe by using a model where we exclude all particles except the leptons and photons. We assume a temperature dependent viscosity as calculated recently by one of us (Husdal in Astrophys. Space Sci. 361(8):1, 2016b) with the use of relativistic kinetic theory. We consider only the bulk viscosity, the shear viscosity being omitted because of spatial isotropy. The rate of entropy production is highest just before the neutrinos decouple. Our results show that the increase in entropy during the lepton era is quite small, about 0.071 % at a decoupling temperature of T=10^{10} K. This result is slightly smaller than that obtained earlier by Caderni and Fabbri (Phys. Lett. B 69:508, 1977). After the neutrino decoupling, when the Universe has entered the photon era, kinetic theory arguments no longer support the appearance of a bulk viscosity. At high temperatures and a stable particle ratio, entropy production (d{σ }/d{T}) goes as T^{-8}, with the total entropy (Δ σ) increasing as T^{-7}. These rates go slightly down just before the neutrinos decouple, where Δσ∝ T^{-6.2}.
4. Production and testing of the VITAMIN-B6 fine-group and the BUGLE-93 broad-group neutron/photon cross-section libraries derived from ENDF/B-VI nuclear data
SciTech Connect
Ingersoll, D.T.; White, J.E.; Wright, R.Q.; Hunter, H.T.; Slater, C.O.; Greene, N.M.; MacFarlane, R.E.
1993-11-01
A new multigroup cross-section library based on ENDF/B-VI data has been produced and tested for light water reactor shielding and reactor pressure vessel dosimetry applications. The broad-group library is designated BUGLE-93. The processing methodology is consistent with ANSI/ANS 6.1.2, since the ENDF data were first processed into a fine-group, pseudo problem-independent format and then collapsed into the final broad-group format. The fine-group library is designated VITAMIN-B6. An extensive integral data testing effort was also performed. In general, results using the new data show significant improvements relative to earlier ENDF data.
5. Production and Testing of the VITAMIN-B6 Fine Group and the BUGLE-93 Broad-Group Neutron/Photon Cross-Section Libraries Derived from ENDF/B-VI Nuclear Data
SciTech Connect
White, J.E.
2001-04-19
A revised multigroup cross-section library based on Release 3 of ENDF/B-VI data has been produced and tested for light-water-reactor shielding and reactor pressure vessel dosimetry applications. This new broad-group library, which is designated BUGLE-96, represents an improvement over the BUGLE-93 data library released in February 1994 and replaces the data package for BUGLE-93 in the Radiation Safety Information Computational Center (formerly RSIC). The processing methodology is the same as that used for producing BUGLE-93 and is consistent with ANSI/ANS 6.1.2. The ENDF data were first processed into a fine-group, pseudo-problem-independent format and then collapsed into the final broad-group format. The fine-group library, which is designated VITAMIN-B6, contains 120 nuclides. The BUGLE-96 47-neutron-group/20-gamma-ray-group library contains the same 120 nuclides processed as infinitely dilute and collapsed using a weighting spectrum typical of a concrete shield. Additionally, nuclides processed with resonance self-shielding and weighted using spectra specific to BWR and PWR material compositions and reactor models are available. As an added feature of BUGLE-96, cross-section sets having upscatter data for four thermal neutron groups are included. The upscattering data should improve the application of BUGLE-96 to the calculation of more accurate thermal fluences, although more computer time will be required. Several new dosimetry response functions and kerma factors for all 120 nuclides are also included in the library. The incorporation of feedback from users has resulted in a data library that addresses a wider spectrum of user needs.
6. Determination of Two-Photon Absorption Cross-Section of Noble Gases for Calibration of Laser Spectroscopic Techniques
SciTech Connect
Rosa, M. I. de la; Perez, C.; Gruetzmacher, K.; Fuentes, L. M.
2008-10-22
The objective of our work is to apply two-photon polarization spectroscopy as a new calibration method for the determination of two-photon excitation cross-sections of noble gases, like Xe and Kr, which are commonly used for calibrations of MP-LIF techniques in other laboratories.
7. Determination of acceptor-to-donor cross section ratio for two-photon excitation in living cells
Hou, Zexian; Wang, Yuhua; Zheng, Liqin; Chen, Tongsheng; Yang, Hongqin; Xie, Shusen
2016-10-01
The cross section is a significant parameter for fluorescence protein and determination of acceptor-to-donor cross section ratio for two-photon excitation in living cells is the vital issue for two-photon excitation FRET quantification. In this study, Hela cells were labeled with FPs that acceptor-to-donor concentration ratio is 1 to 1 and acceptor-to-donor cross section ratio ranged from 700nm to 960nm was obtained by emission spectral unmixing with independent excitation crosstalk correction. The results show that acceptor-to-donor cross section ratio declines with the excitation wavelength from 700nm to 790nm and then increases inversely from 790nm to 960nm. This method can quickly determine the cross section without any additional references, which could provide a powerful and convenient tool for measuring acceptor-to-donor cross section ratio by two-photon excitation in living cells.
8. Study of isolated prompt photon production in p -Pb collisions for the ALICE kinematics
2017-03-01
Prompt photon production is known as a powerful tool for testing perturbative QCD predictions and also the validity of parton densities in the nucleon and nuclei, especially of the gluon. In this work, we have performed a detailed study on this subject, focusing on the isolated prompt photon production in p -Pb collisions at forward rapidity at the LHC. The impact of input nuclear modifications obtained from different global analyses by various groups on several quantities has been investigated to estimate the order of magnitude of the difference between their predictions. We have also studied in detail the theoretical uncertainties in the results due to various sources. We found that there is a remarkable difference between the predictions from the nCTEQ15 and other groups in all ranges of photon transverse momentum pTγ. Their differences become more explicit in the calculation of the nuclear modification ratio and also the yield asymmetry between the forward and backward rapidities rather than single differential cross sections. We emphasize that future measurements with ALICE will be very useful, not only for decreasing the uncertainty of the gluon nuclear modification, but also to accurately determine its central values, especially in the shadowing region.
9. Heavy quark production in photon-Pomeron interactions at high energies
SciTech Connect
Machado, M. M.; Goncalves, V. P.
2013-03-25
The diffractive heavy quark cross sections are estimated considering photon-Pomeron interactions in hadron - hadron at RHIC, Tevatron, and CERN LHC energies. We assume the validity of the hard diffractive factorization and calculate the charm and bottom total cross sections and rapidity distributions using the diffractive parton distribution functions of the Pomeron obtained by the H1 Collaboration at DESY-HERA. Such processes are sensitive to the gluon content of the Pomeron at high energies and are a good place to constrain the behavior of this distribution. We also compare our predictions with those obtained using the dipole model, and verify that these processes are a good test of the different mechanisms for heavy quarks diffractive production at hadron colliders.
10. Deterministic distribution of four-photon Dicke state over an arbitrary collective-noise channel with cross-Kerr nonlinearity
PubMed Central
Wang, Mei-Yu; Yan, Feng-Li; Gao, Ting
2016-01-01
We present two deterministic quantum entanglement distribution protocols for a four-photon Dicke polarization entangled state resorting to the frequency and spatial degrees of freedom, which are immune to an arbitrary collective-noise channel. Both of the protocols adopt the X homodyne measurement based on the cross-Kerr nonlinearity to complete the task of the single-photon detection with nearly unit probability in principle. After the four receivers share the photons, they add some local unitary operations to obtain a standard four-photon Dicke polarization entangled state. PMID:27412489
11. Study of the associated production of photons and b-quark jets in pp¯ collisions at s=1.96TeV
Aaltonen, T.; Adelman, J.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauer, G.; Beauchemin, P.-H.; Bedeschi, F.; Beecher, D.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.; Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.; Dagenhart, D.; Datta, M.; Davies, T.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca, C.; Demortier, L.; Deng, J.; Deninno, M.; D'Errico, M.; di Canto, A.; di Giovanni, G. P.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, T.; Dube, S.; Ebina, K.; Elagin, A.; Erbacher, R.; Errede, D.; Errede, S.; Ershaidat, N.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; Guimaraes da Costa, J.; Gunay-Unalan, Z.; Haber, C.; Hahn, S. R.; Halkiadakis, E.; Han, B.-Y.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hartz, M.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussein, M.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin, P. E.; Kato, Y.; Kephart, R.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leone, S.; Lewis, J. D.; Lin, C.-J.; Linacre, J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.; Loginov, A.; Lovas, L.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; MacQueen, D.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Mastrandrea, P.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione, A.; Mesropian, C.; Miao, T.; Mietlicki, D.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Nielsen, J.; Nodulman, L.; Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Osterberg, K.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramanov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Potamianos, K.; Poukhov, O.; Prokoshin, F.; Pronko, A.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Renz, M.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ, J.; Rusu, V.; Rutherford, B.; Saarikko, H.; Safonov, A.; Sakumoto, W. K.; Santi, L.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon, Y.; Shreyber, I.; Simonenko, A.; Sinervo, P.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur, R.; Soha, A.; Somalwar, S.; Sorin, V.; Squillacioti, P.; Stanitzki, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Tipton, P.; Ttito-Guzmán, P.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Tourneur, S.; Trovato, M.; Tsai, S.-Y.; Tu, Y.; Turini, N.; Ukegawa, F.; Uozumi, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar, R.; Vogel, M.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Weinelt, J.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wolfe, H.; Wright, T.; Wu, X.; Würthwein, F.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.; Zhang, X.; Zheng, Y.; Zucchelli, S.; CDF Collaboration
2010-03-01
The cross section for photon production in association with at least one jet containing a b quark has been measured in proton antiproton collisions at s=1.96TeV. The data sample used corresponds to an integrated luminosity of 340pb-1 collected with the CDF II detector. Both the differential cross section as a function of photon transverse energy ETγ and the total cross section are measured and compared to a next-to-leading order prediction for the process.
12. Quantum computation based on photonic systems with two degrees of freedom assisted by the weak cross-Kerr nonlinearity.
PubMed
Luo, Ming-Xing; Li, Hui-Ran; Lai, Hong
2016-07-18
Most of previous quantum computations only take use of one degree of freedom (DoF) of photons. An experimental system may possess various DoFs simultaneously. In this paper, with the weak cross-Kerr nonlinearity, we investigate the parallel quantum computation dependent on photonic systems with two DoFs. We construct nearly deterministic controlled-not (CNOT) gates operating on the polarization spatial DoFs of the two-photon or one-photon system. These CNOT gates show that two photonic DoFs can be encoded as independent qubits without auxiliary DoF in theory. Only the coherent states are required. Thus one half of quantum simulation resources may be saved in quantum applications if more complicated circuits are involved. Hence, one may trade off the implementation complexity and simulation resources by using different photonic systems. These CNOT gates are also used to complete various applications including the quantum teleportation and quantum superdense coding.
13. Quantum computation based on photonic systems with two degrees of freedom assisted by the weak cross-Kerr nonlinearity
Luo, Ming-Xing; Li, Hui-Ran; Lai, Hong
2016-07-01
Most of previous quantum computations only take use of one degree of freedom (DoF) of photons. An experimental system may possess various DoFs simultaneously. In this paper, with the weak cross-Kerr nonlinearity, we investigate the parallel quantum computation dependent on photonic systems with two DoFs. We construct nearly deterministic controlled-not (CNOT) gates operating on the polarization spatial DoFs of the two-photon or one-photon system. These CNOT gates show that two photonic DoFs can be encoded as independent qubits without auxiliary DoF in theory. Only the coherent states are required. Thus one half of quantum simulation resources may be saved in quantum applications if more complicated circuits are involved. Hence, one may trade off the implementation complexity and simulation resources by using different photonic systems. These CNOT gates are also used to complete various applications including the quantum teleportation and quantum superdense coding.
14. Using DNA origami nanostructures to determine absolute cross sections for UV photon-induced DNA strand breakage.
PubMed
Vogel, Stefanie; Rackwitz, Jenny; Schürman, Robin; Prinz, Julia; Milosavljević, Aleksandar R; Réfrégiers, Matthieu; Giuliani, Alexandre; Bald, Ilko
2015-11-19
We have characterized ultraviolet (UV) photon-induced DNA strand break processes by determination of absolute cross sections for photoabsorption and for sequence-specific DNA single strand breakage induced by photons in an energy range from 6.50 to 8.94 eV. These represent the lowest-energy photons able to induce DNA strand breaks. Oligonucleotide targets are immobilized on a UV transparent substrate in controlled quantities through attachment to DNA origami templates. Photon-induced dissociation of single DNA strands is visualized and quantified using atomic force microscopy. The obtained quantum yields for strand breakage vary between 0.06 and 0.5, indicating highly efficient DNA strand breakage by UV photons, which is clearly dependent on the photon energy. Above the ionization threshold strand breakage becomes clearly the dominant form of DNA radiation damage, which is then also dependent on the nucleotide sequence.
15. Prompt J /ψ production in association with a c c ¯ pair within the framework of nonrelativistic QCD via photon-photon collisions at the International Linear Collider
Sun, Zhan; Wu, Xing-Gang; Zhang, Hong-Fei
2015-10-01
We present a systematical study on the prompt J /ψ production in association with a c c ¯ pair via the process, γ γ →H (c c ¯)+c +c ¯, within the framework of nonrelativistic QCD at the future high-energy e+e- collider—International Linear Collider (ILC), including both direct and feed-down contributions. For direct J /ψ production, the states with color-octet channels, especially the P3 J[8] and S1 0[8] ones, provide a dominant contribution to the production cross section, which are about 52 times over that of the color-singlet one. This is clearly shown by the transverse momentum (pt) and rapidity distributions. The feed-down contribution from ψ' and χc J (J =0 , 1, 2) is sizable, which is about 20% to the total prompt cross section. Besides the yields, we also calculate the J /ψ polarization parameter λ . In the small pt region, the polarization of the prompt J /ψ is longitudinal due to large contributions through the P3 J[8] channel, and becomes transverse in the high pt region due to the S3 1[8] channel. Thus the J /ψ production via photon-photon collisions at the ILC shall provide a useful platform for testing the color-octet mechanism.
16. Solidity of Type III Bernoulli Crossed Products
Marrakchi, Amine
2017-03-01
We generalize a theorem of Chifan and Ioana by proving that for any, possibly type III, amenable von Neumann algebra A 0, any faithful normal state φ_0 and any discrete group {Γ}, the associated Bernoulli crossed product von Neumann algebra {M=(A_0,φ_0)^{overline{⊗} Γ} rtimes Γ} is solid relatively to L(Γ). In particular, if L(Γ) is solid then M is solid and if {Γ} is non-amenable and {A_0 ≠ C then M is a full prime factor. This gives many new examples of solid or prime type III factors. Following Chifan and Ioana, we also obtain the first examples of solid non-amenable type III equivalence relations.
17. General calculation of the cross section for dark matter annihilations into two photons
Garcia-Cely, Camilo; Rivera, Andres
2017-03-01
Assuming that the underlying model satisfies some general requirements such as renormalizability and CP conservation, we calculate the non-relativistic one-loop cross section for any self-conjugate dark matter particle annihilating into two photons. We accomplish this by carefully classifying all possible one-loop diagrams and, from them, reading off the dark matter interactions with the particles running in the loop. Our approach is general and leads to the same results found in the literature for popular dark matter candidates such as the neutralinos of the MSSM, minimal dark matter, inert Higgs and Kaluza-Klein dark matter.
18. Measurement of the energy dependence of the total photon-proton cross section at HERA
2011-03-01
The energy dependence of the photon-proton total cross section, σtotγp, was determined from e+p scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194
19. Measurement of the energy dependence of the total photon-proton cross section at HERA
2011-03-01
The energy dependence of the photon-proton total cross section, σtotγp, was determined from ep scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194
20. Measurement of the inclusive isolated prompt photon cross section in pp collisions at √s=7 TeV with the ATLAS detector
DOE PAGES
Aad, G.; Abbott, B.; Abdallah, J.; ...
2011-03-18
A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy √s=7 TeV is presented. The measurement covers the pseudorapidity ranges |ηγ|<1.37 and 1.52≤|ηγ|<1.81 in the transverse energy range 15≤EγT<100 GeV. The results are based on an integrated luminosity of 880 nb-1, collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrowmore » cone around the photon candidate. The results are compared to predictions from next-to-leading-order perturbative QCD calculations.« less
1. Study of π0 pair production in single-tag two-photon collisions
Masuda, M.; Uehara, S.; Watanabe, Y.; Nakazawa, H.; Abdesselam, A.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Babu, V.; Badhrees, I.; Bakich, A. M.; Barberio, E.; Behera, P.; Bhuyan, B.; Biswal, J.; Bobrov, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Browder, T. E.; Červenkov, D.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Chistov, R.; Cho, K.; Chobanova, V.; Choi, S.-K.; Choi, Y.; Cinabro, D.; Dalseno, J.; Danilov, M.; Dash, N.; Dingfelder, J.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gillard, R.; Giordano, F.; Glattauer, R.; Goh, Y. M.; Goldenzweig, P.; Golob, B.; Haba, J.; Hayasaka, K.; Hayashii, H.; He, X. H.; Hou, W.-S.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Jaegle, I.; Joffe, D.; Joo, K. K.; Julius, T.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kim, D. Y.; Kim, J. B.; Kim, J. H.; Kim, K. T.; Kim, M. J.; Kim, S. H.; Kim, Y. J.; Ko, B. R.; Korpar, S.; Križan, P.; Krokovny, P.; Kumita, T.; Kuzmin, A.; Kwon, Y.-J.; Lange, J. S.; Lee, D. H.; Lee, I. S.; Li, C.; Li, L.; Li, Y.; Libby, J.; Liventsev, D.; Lukin, P.; Matvienko, D.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Mohanty, S.; Moll, A.; Moon, H. K.; Mori, T.; Mussa, R.; Nakano, E.; Nakao, M.; Nanut, T.; Natkaniec, Z.; Nayak, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Park, C. W.; Park, H.; Pedlar, T. K.; Pestotnik, R.; Petrič, M.; Piilonen, L. E.; Rauch, J.; Ribežl, E.; Ritter, M.; Rostomyan, A.; Sandilya, S.; Santelj, L.; Sanuki, T.; Sato, Y.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seino, Y.; Senyo, K.; Seon, O.; Sevior, M. E.; Shebalin, V.; Shen, C. P.; Shibata, T.-A.; Shiu, J.-G.; Shwartz, B.; Simon, F.; Sohn, Y.-S.; Sokolov, A.; Solovieva, E.; Starič, M.; Sumihama, M.; Sumiyoshi, T.; Tamponi, U.; Tanida, K.; Teramoto, Y.; Uglov, T.; Unno, Y.; Uno, S.; Van Hulse, C.; Vanhoefer, P.; Varner, G.; Vinokurova, A.; Vorobyev, V.; Vossen, A.; Wagner, M. N.; Wang, C. H.; Wang, M.-Z.; Wang, P.; Williams, K. M.; Won, E.; Yamaoka, J.; Yamashita, Y.; Yashchenko, S.; Ye, H.; Yusa, Y.; Zhang, C. C.; Zhang, Z. P.; Zhilich, V.; Zhulanov, V.; Zupanc, A.; Belle Collaboration
2016-02-01
We report a measurement of the differential cross section of π0 pair production in single-tag two-photon collisions, γ*γ →π0π0, in e+e- scattering. The cross section is measured for Q2 up to 30 GeV2, where Q2 is the negative of the invariant mass squared of the tagged photon, in the kinematic range 0.5 GeV
2. Anomalous photon-gauge boson coupling contribution to the exclusive vector boson pair production from two photon exchange in pp collisions at 13 TeV
Martins, D. E.; Rebello Teles, P.; Vilela Pereira, A.; Sá Borges, J.
2015-04-01
We study the W and Z pair production from two-photon exchange in proton-proton collisions at the LHC in order to evaluate the contributions of anomalous photon-gauge boson couplings, that simulates new particles and couplings predicted in many Standard Model (SM) extensions. The experimental results of W+ W- exclusive production (pp → pW+W- p) at 7 TeV from the CMS collaboration [1] updates the experimental limits on anomalous couplings obtained at the Large Electron-Positron Collider (LEP). This motivates our present analysis hopefully anticipating the expected results using the Precision Proton Spectrometer (PPS) to be installed as part of CMS. In this work, we consider the W+W- exclusive production to present the pT distribution of the lepton pair corresponding to the SM signal with pT (e, μ) > 10 GeV. Next, we consider the photon-gauge boson anomalous couplings by calculating, from the FPMC and MadGraph event generators, the process γγ → W+W- from a model with gauge boson quartic couplings, by considering a 1 TeV scale for new physical effects. We present our results for an integrated luminosity of 5 fb-1 at center-of-mass energy of 7 TeV and for an integrated luminosity of 100 fb-1 at 13 TeV. We present our preliminary results for Z pair exclusive production from two-photon exchange with anomalous couplings, where the ZZγγ quartic coupling is absent in the SM. We calculate the total cross section for the exclusive process and present the four lepton invariant mass distribution. Finally we present an outlook for the present analysis.
3. Anomalous photon-gauge boson coupling contribution to the exclusive vector boson pair production from two photon exchange in pp collisions at 13 TeV
SciTech Connect
Martins, D. E.; Vilela Pereira, A.; Sá Borges, J.; Rebello Teles, P.
2015-04-10
We study the W and Z pair production from two-photon exchange in proton-proton collisions at the LHC in order to evaluate the contributions of anomalous photon-gauge boson couplings, that simulates new particles and couplings predicted in many Standard Model (SM) extensions. The experimental results of W{sup +} W{sup −} exclusive production (pp → pW{sup +}W{sup −} p) at 7 TeV from the CMS collaboration [1] updates the experimental limits on anomalous couplings obtained at the Large Electron-Positron Collider (LEP). This motivates our present analysis hopefully anticipating the expected results using the Precision Proton Spectrometer (PPS) to be installed as part of CMS. In this work, we consider the W{sup +}W{sup −} exclusive production to present the p{sub T} distribution of the lepton pair corresponding to the SM signal with p{sub T} (e, μ) > 10 GeV. Next, we consider the photon-gauge boson anomalous couplings by calculating, from the FPMC and MadGraph event generators, the process γγ → W{sup +}W{sup −} from a model with gauge boson quartic couplings, by considering a 1 TeV scale for new physical effects. We present our results for an integrated luminosity of 5 fb{sup −1} at center-of-mass energy of 7 TeV and for an integrated luminosity of 100 fb{sup −1} at 13 TeV. We present our preliminary results for Z pair exclusive production from two-photon exchange with anomalous couplings, where the ZZγγ quartic coupling is absent in the SM. We calculate the total cross section for the exclusive process and present the four lepton invariant mass distribution. Finally we present an outlook for the present analysis.
4. Nuclear Recoil Cross Sections from Time-dependent Studies of Two-Photon Double Ionization of Helium
SciTech Connect
Horner, Daniel A.; Rescigno, Thomas N.; McCurdy, C. William
2009-12-21
We examine the sensitivity of nuclear recoil cross sections produced by two-photon double ionization of helium to the underlying triple differential cross sections (TDCS) used in their computation. We show that this sensitivity is greatest in the energy region just below the threshold for sequential double ionization. Accurate TDCS, extracted from non-perturbative solutions of the time-dependent Schroedinger equation, are used here in new computations of the nuclear recoil cross section.
5. Direct photon production in high-energy nuclear collisions
SciTech Connect
Peitzmann, T.
2016-01-22
Direct photons have always been considered a promising probe for the very early phases of high-energy nuclear collisions. Prompt photons reveal information about the initial state and its possible modifications in nuclei. In this context they should be one of the best probes for effects of gluon saturation. Thermal photons emitted from the produced matter in nuclear collisions carry information on the temperature of the very early phase. In particular a simultaneous measurement of yield and elliptic flow of thermal photons can put strong constraints on the early time dynamics of the system. I review the status of results on direct photon measurements at RHIC and LHC and their interpretation. Prompt photons at high p{sub T} are consistent with expectations from NLO pQCD in pp and show no strong nuclear modifications in A–A collisions. Recent analysis at RHIC has shown very intriguing results for lower p{sub T}, with high thermal photon yield and strong elliptic flow of direct photons, which are not fully understood theoretically. Also the ALICE experiment at the LHC has measured a high yield of thermal photons. Furthermore I discuss prospects for future measurements of forward direct photons at the LHC.
6. Further Results on the Production of Neutral Mesons by Photons
DOE R&D Accomplishments Database
Panofsky, W. K. H.; Steinberger, J.; Steller, J.
1951-10-01
Further measurements have been made on the photoproduction of neutral mesons using the gamma-gamma coincidence technique. New data have been obtained on the gamma-gamma correlation curves in beryllium. The angular distribution of the photo mesons in Be has been determined and found to be strongly peaked forward. The dependence on the atomic number A of production has been found to obey an A{sup 2/3} law. Some data obtained for production in hydrogen show that the pi-zero and pi-plus production cross sections are comparable and that the pi-zero excitation curve starts more slowly from threshold than does the pi-plus photo excitation curve.
7. Photon pair production from a hot atomic ensemble in the diamond configuration
Willis, Richard Thomas
This thesis discusses four-wave mixing (4WM) in a warm ensemble of rubidium using the diamond configuration level structure. Both classical 4WM and nonclassical photon-pair production are investigated. Quantum information science has spawned a great amount of experimental work on the interaction of light with collective modes of excitation in atomic ensembles. Plans to build quantum networks and quantum repeaters with atom ensembles take advantage of nonlinear interactions to produce and store non-classical states of light. These technologies will require photon sources that not only generate nonclassical light, but also resonant, narrow band light. Here we investigate a system which could be used as such a source. We take advantage of the 4WM interaction in a warm ensemble of Rubidium atoms. Our scheme utilizes the diamond energy level configuration which, in rubidium, allows for correlated pairs at telecommunications wavelengths. We start by examining the properties of classical 4WM in the system. We measure the resonance structure and see that it can be understood in terms of velocity class selective resonant enhancement and power splitting effects. The efficiency of the process is low and limited by linear absorption of the pumps. Our observations agree with a semi-classical Maxwell-Bloch theoretical treatment. Next we observe pair generation by spontaneous 4WM from the warm ensemble. The temporal profile of the cross-correlation function (CCF) for the photons depends on pump-laser power and detuning. This allows us to produce biphotons with controllable spectra. A simple quantum optical theoretical treatment based on linear filtering gives qualitative agreement with the data. We show that the photon pairs are polarization entangled, clearly violating Bell's Inequality. A perturbative quantum optical treatment predicts the polarization state of the pairs and agrees with our measurements. We analyze the photon statistics of the source and find the largest
8. Production of photons in relativistic heavy-ion collisions
DOE PAGES
Jean -Francois Paquet; Denicol, Gabriel S.; Shen, Chun; ...
2016-04-18
In this work it is shown that the use of a hydrodynamical model of heavy-ion collisions which incorporates recent developments, together with updated photon emission rates, greatly improves agreement with both ALICE and PHENIX measurements of direct photons, supporting the idea that thermal photons are the dominant source of direct photon momentum anisotropy. The event-by-event hydrodynamical model uses the impact parameter dependent Glasma model (IP-Glasma) initial states and includes, for the first time, both shear and bulk viscosities, along with second-order couplings between the two viscosities. Furthermore, the effect of both shear and bulk viscosities on the photon rates ismore » studied, and those transport coefficients are shown to have measurable consequences on the photon momentum anisotropy.« less
9. Production of photons in relativistic heavy-ion collisions
SciTech Connect
Jean -Francois Paquet; Denicol, Gabriel S.; Shen, Chun; Luzum, Matthew; Schenke, Bjorn; Jeon, Sangyong; Gale, Charles
2016-04-18
In this work it is shown that the use of a hydrodynamical model of heavy-ion collisions which incorporates recent developments, together with updated photon emission rates, greatly improves agreement with both ALICE and PHENIX measurements of direct photons, supporting the idea that thermal photons are the dominant source of direct photon momentum anisotropy. The event-by-event hydrodynamical model uses the impact parameter dependent Glasma model (IP-Glasma) initial states and includes, for the first time, both shear and bulk viscosities, along with second-order couplings between the two viscosities. Furthermore, the effect of both shear and bulk viscosities on the photon rates is studied, and those transport coefficients are shown to have measurable consequences on the photon momentum anisotropy.
10. Inclusive Cross Section Production of J/ψ in LEP
Osati, T.; Abubakri, B.
2017-02-01
Cross section production is one of the observable quantities in the hadronic systems. Inclusive cross section production J/ψ may be calculated through the use of the fragmentation c → J/ψ. In this paper we calculate the inclusive cross section production J/ψ about the pole of Z 0 in the e + e ‑ annihilation, through the lowest order regim of perturbative of QCD ananlyticaly. The obtained results arrive an excellent agreement with the exprimental data to produce the inclusive cross section production c → J/ψ.
11. Measurement of K* K* production in two-photon interactions
ARGUS Collaboration; Albrecht, H.
2000-09-01
A measurement of gamma gamma production of the final states K^+ K^- π^+ π ^-, K^+ K^- π^0 π ^0, K^0_SK^0_Sπ^+π^-, K^0_S K^{±} π^{mp} π^0 and K^0_SK^0_Sπ^0π^0 was performed by the ARGUS collaboration at the e^+e^- storage ring DORIS II at DESY. Since the two intermediate states K^{*0} bar{K}^{*0} and K^{*+}K^{*-} are accessible by analysing different final states, the measurement provides several cross checks for cross-sections to these two states. The results for γγ to K^{*}bar{K}^* cross-sections obtained from different final states are found to be consistent with each other. The analysis of the partial wave structure of the K^{*0}bar{K}^{*0} state from the reaction γ γ to K^+ K^- π^+ π ^- revealed the dominance of the (J^P,J_z) = (2^+,± 2) wave.
12. High-statistics study of K0S pair production in two-photon collisions
Uehara, S.; Watanabe, Y.; Nakazawa, H.; Adachi, I.; Aihara, H.; Asner, D. M.; Aulchenko, V.; Aushev, T.; Bakich, A. M.; Bala, A.; Bhardwaj, V.; Bhuyan, B.; Bondar, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Chekelian, V.; Chen, A.; Chen, P.; Cheon, B. G.; Chilikin, K.; Chistov, R.; Cho, K.; Chobanova, V.; Choi, S.-K.; Choi, Y.; Cinabro, D.; Dalseno, J.; Dingfelder, J.; Doležal, Z.; Dutta, D.; Eidelman, S.; Epifanov, D.; Farhat, H.; Fast, J. E.; Feindt, M.; Ferber, T.; Frey, A.; Gaur, V.; Gabyshev, N.; Ganguly, S.; Gillard, R.; Giordano, F.; Goh, Y. M.; Golob, B.; Haba, J.; Hayasaka, K.; Hayashii, H.; Hoshi, Y.; Hou, W.-S.; Hyun, H. J.; Iijima, T.; Ishikawa, A.; Itoh, R.; Iwasaki, Y.; Julius, T.; Kah, D. H.; Kang, J. H.; Kato, E.; Kawai, H.; Kawasaki, T.; Kiesling, C.; Kim, D. Y.; Kim, H. O.; Kim, J. B.; Kim, J. H.; Kim, Y. J.; Klucar, J.; Ko, B. R.; Kodyš, P.; Korpar, S.; Križan, P.; Krokovny, P.; Kumita, T.; Kuzmin, A.; Kwon, Y.-J.; Lee, S.-H.; Li, J.; Li, Y.; Liu, C.; Liu, Z. Q.; Liventsev, D.; Lukin, P.; Matvienko, D.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Moll, A.; Mori, T.; Muramatsu, N.; Mussa, R.; Nagasaka, Y.; Nakao, M.; Ng, C.; Nisar, K. N.; Nishida, S.; Nitoh, O.; Ogawa, S.; Okuno, S.; Pakhlova, G.; Park, C. W.; Park, H.; Park, H. K.; Pedlar, T. K.; Pestotnik, R.; Petrič, M.; Piilonen, L. E.; Ritter, M.; Röhrken, M.; Rostomyan, A.; Sahoo, H.; Saito, T.; Sakai, Y.; Sandilya, S.; Santelj, L.; Sanuki, T.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seidl, R.; Senyo, K.; Seon, O.; Shapkin, M.; Shen, C. P.; Shibata, T.-A.; Shiu, J.-G.; Shwartz, B.; Sibidanov, A.; Simon, F.; Sohn, Y.-S.; Sokolov, A.; Solovieva, E.; Starič, M.; Steder, M.; Sumihama, M.; Sumiyoshi, T.; Tamponi, U.; Tanida, K.; Tatishvili, G.; Teramoto, Y.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Vahsen, S. E.; Van Hulse, C.; Varner, G.; Wagner, M. N.; Wang, C. H.; Wang, M.-Z.; Wang, P.; Wang, X. L.; Williams, K. M.; Won, E.; Yamashita, Y.; Yashchenko, S.; Yook, Y.; Yuan, C. Z.; Yusa, Y.; Zhang, C. C.; Zhang, Z. P.; Zhilich, V.; Zhulanov, V.; Zupanc, A.
2013-12-01
We report a high-statistics measurement of the differential cross section of the process γ γ to K^0_S K^0_S in the range 1.05 {GeV} ≤ W ≤ 4.00 GeV, where W is the center-of-mass energy of the colliding photons, using 972 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider operated at and near the Upsilon -resonance region. The differential cross section is fitted by parameterized S-, D_0-, D_2-, G_0-, and G_2-wave amplitudes. In the D_2 wave, the f_2(1270), a_2(1320), and f_2'(1525) are dominant and a resonance, the f_2(2200), is also present. The f_0(1710) and possibly the f_0(2500) are seen in the S wave. The mass, total width, and product of the two-photon partial decay width and decay branching fraction to the K bar {K} state Γ _{γ γ }mathcal {B}(K bar {K}) are extracted for the f_2'(1525), f_0(1710), f_2(2200), and f_0(2500). The destructive interference between the f_2(1270) and a_2(1320) is confirmed by measuring their relative phase. The parameters of the charmonium states χ _{c0} and χ _{c2} are updated. Possible contributions from the χ _{c0}(2P) and χ _{c2}(2P) states are discussed. A new upper limit for the branching fraction of the P- and CP-violating decay channel η _c to K^0_S K^0_S is reported. The detailed behavior of the cross section is updated and compared with QCD-based calculations.
13. High Transverse Momentum Direct Photon Production at Fermilab Fixed-Target Energies
SciTech Connect
Apanasevich, Leonard
2005-01-01
This thesis describes a study of the production of high transverse momentum direct photons and π0 mesons by proton beams at 530 and 800 GeV/c and π- beams at 515 GeV/c incident on beryllium, copper, and liquid hydrogen targets. The data were collected by Fermilab experiment E706 during the 1990 and 1991-92 fixed target runs. The apparatus included a large, finely segmented lead and liquid argon electromagnetic calorimeter and a charged particle spectrometer featuring silicon strip detectors in the target region and proportional wire chambers and drift tubes downstream of a large aperture analysis magnet. The inclusive cross sections are presented as functions of transverse momentum and rapidity. The measurements are compared with next-to-leading order perturbative QCD calculations and to results from previous experiments.
14. Probing the neutron-skin thickness by photon production from reactions induced by intermediate-energy protons
Wei, Gao-Feng
2015-07-01
The photon from neutron-proton bremsstrahlung in p +Pb reactions is examined as a potential probe of the neutron-skin thickness in different centralities and at different proton incident energies. It is shown that the best choice of reaction environment is about 140 MeV for the incident proton and the 95%-100% centrality for the reaction system since the incident proton mainly interacts with neutrons inside the skin of the target and thus leads to different photon production to a maximal extent. Moreover, considering two main uncertainties from both photon production probability and nucleon-nucleon cross section in the reaction, I propose to use the ratio of photon production from two reactions to measure the neutron-skin thickness because of its cancellation effects on these uncertainties simultaneously, but preserved about 13%-15% sensitivities on the varied neutron-skin thickness from 0.1 to 0.3 fm within the current experimental uncertainty range of the neutron-skin size in 208Pb.
15. Differential cross section of γn→K+Σ- on bound neutrons with incident photons from 1.1 to 3.6 GeV
DOE PAGES
Pereira, S. Anefalos; Mirazita, M.; Rossi, P.; ...
2010-05-01
Differential cross sections of the reaction γd → K+Σ–(p) have been measured with the CLAS detector at Jefferson Lab using incident photons with energies between 1.1 and 3.6 GeV. This is the first complete set of strangeness photoproduction data on the neutron covering a broad angular range. At energies close to threshold and up to Eγ ~ 1.8 GeV, the shape of the angular distribution is suggestive of the presence of s -channel production mechanisms. For Eγ > 1.8 GeV, a clear forward peak appears and becomes more prominent as the photon energy increases, suggesting contributions from t-channel production mechanisms.more » Furthermore, these data can be used to constrain future analysis of this reaction.« less
16. Enhancing Photon Utilization Efficiency for Astaxanthin Production from Haematococcus lacustris Using a Split-Column Photobioreactor.
PubMed
Kim, Z-Hun; Park, Hanwool; Lee, Ho-Sang; Lee, Choul-Gyun
2016-07-28
A split-column photobioreactor (SC-PBR), consisting of two bubble columns with different sizes, was developed to enhance the photon utilization efficiency in an astaxanthin production process from Haematococcus lacustris. Among the two columns, only the smaller column of SC-PBR was illuminated. Astaxanthin productivities and photon efficiencies of the SC-PBRs were compared with a standard bubble-column PBR (BC-PBR). Astaxanthin productivity of SC-PBR was improved by 28%, and the photon utilization efficiencies were 28-366% higher than the original BC-PBR. The results clearly show that the effective light regime of SC-PBR could enhance the production of astaxanthin.
17. Next-to-leading order QCD predictions for graviton and photon associated production in the large extra dimensions model at the LHC
SciTech Connect
Gao Xiangdong; Li Chongsheng; Gao Jun; Wang Jian; Oakes, Robert J.
2010-02-01
We present the calculations of the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein (KK) graviton and photon associated production process pp{yields}{gamma}G{sub KK}+X in the large extra dimensions model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution, and the pseudorapidity distribution of photon.
18. Direct photon production in d+Au collisions at sNN=200 GeV
2013-05-01
Direct photons have been measured in sNN=200 GeV d+Au collisions at midrapidity. A wide pT range is covered by measurements of nearly real virtual photons (1photons (5photons in d+Au collisions over the scaled p+p cross section is consistent with unity. Theoretical calculations assuming standard cold-nuclear-matter effects describe the data well for the entire pT range. This indicates that the large enhancement of direct photons observed in Au+Au collisions for 1.0
19. The Lyman-continuum photon production efficiency in the high-redshift Universe
Wilkins, Stephen M.; Feng, Yu; Di-Matteo, Tiziana; Croft, Rupert; Stanway, Elizabeth R.; Bouwens, Rychard J.; Thomas, Peter
2016-05-01
The Lyman-continuum photon production efficiency (ξion) is a critical ingredient for inferring the number of photons available to reionize the intergalactic medium. To estimate the theoretical production efficiency in the high-redshift Universe we couple the BlueTides cosmological hydrodynamical simulation with a range of stellar population synthesis models. We find Lyman-continuum photon production efficiencies of log10(ξion/erg-1 Hz) ≈ 25.1-25.5 depending on the choice of stellar population synthesis model. These results are broadly consistent with recent observational constraints at high-redshift though favour a model incorporating the effects of binary evolution.
20. Preparation of four-photon polarization-entangled decoherence-free states employing weak cross-Kerr nonlinearities
Xiu, Xiao-Ming; Li, Qing-Yang; Lin, Yan-Fang; Dong, Hai-Kuan; Dong, Li; Gao, Ya-Jun
2016-10-01
With the assistance of weak cross-Kerr nonlinearities, we present a preparation scheme of four-photon polarization-entangled decoherence-free states, which can be used to construct the minimal optical decoherence-free subspaces where a logical qubit is fully protected against collective decoherence. To complete the preparation task, one spatial entanglement process, two polarization entanglement processes, and one detecting process are applied. The fulfillments of the above processes are contributed by a cross-Kerr nonlinear interaction between the signal photons and a coherent state via Kerr media. Exploiting the available single-photon resource and simple linear optics elements, this scheme is feasible and desirable to be extended to the construction of multiphoton decoherence-free states against the collective decoherence.
1. Heavy-Quark Associated Production with One Hard Photon at Hadron Colliders
SciTech Connect
Hartanto, Heribertus Bayu
2013-01-01
We present the calculation of heavy-quark associated production with a hard photon at hadron colliders, namely $pp(p\\bar p) → Q\\bar Q +X$γ (for $Q=t,b$), at Next-to-Leading Order (NLO) in Quantum Chromodynamics (QCD). We study the impact of NLO QCD corrections on the total cross section and several differential distributions at both the Tevatron and the Large Hadron Collider (LHC). For $t\\bar t$γ production we observe a sizeable reduction of the renormalization and factorization scale dependence when the NLO QCD corrections are included, while for $b\\bar b$γ production a considerable scale dependence still persists at NLO in QCD. This is consistent with what emerges in similar processes involving $b$ quarks and vector bosons and we explain its origin in detail. For $b\\bar b$γ production we study both the case in which at least one $b$ jet and the case in which at least two $b$ jets are observed. We perform the $b\\bar b$γ calculation using the Four Flavor Number Scheme (4FNS) and compare the case where at least one $b$ jet is observed with the corresponding results from the Five Flavor Number Scheme (5FNS) calculation. Finally we compare our results for $p\\bar p →+b+X$γ with the Tevatron data.
2. Label-free detection and discrimination of poly-brominated diphenylethers using molecularly imprinted photonic cross-reactive sensor arrays.
PubMed
Xu, Dan; Zhu, Wei; Wang, Chen; Tian, Tian; Li, Jian; Lan, Yue; Zhang, Guanxin; Zhang, Deqing; Li, Guangtao
2014-11-25
Molecularly imprinted photonic polymers can serve as ideal sensing elements for efficiently creating cross-reactive sensor arrays. Based on this concept, a new method for sensitive and label-free detection of challenging PBDEs was developed, by which the direct detection and discrimination of trace levels of PBDEs against a high-background of interferents was achieved with 100% accuracy.
3. Continuous Sensing Photonic Lab-on-a-Chip Platform Based on Cross-Linked Enzyme Crystals.
PubMed
Conejero-Muriel, Mayte; Rodríguez-Ruiz, Isaac; Verdugo-Escamilla, Cristóbal; Llobera, Andreu; Gavira, José A
2016-12-06
Microfluidics or lab-on-a-chip technology offer clear advantages over conventional systems such as a dramatic reduction of reagent consumption or a shorter analysis time, which are translated into cost-effective systems. In this work, we present a photonic enzymatic lab-on-a-chip reactor based on cross-linked enzyme crystals (CLECs), able to work in continuous flow, as a highly sensitive, robust, reusable, and stable platform for continuous sensing with superior performance as compared to the state of the art. The microreactor is designed to facilitate the in situ crystallization and crystal cross-linking generating enzymatically active material that can be stored for months/years. Thus, and by means of monolithically integrated micro-optics elements, continuous enzymatic reactions can be spectrophotometrically monitored. Lipase, an enzyme with industrial significance for catalyzed transesterification, hydrolysis, and esterification reactions, is used to demonstrate the potential of the microplatforms as both a continuous biosensor and a microreactor for the synthesis of high value compounds.
4. Proton Pair Production Cross Sections at BESIII
Zhou, Xiaorong
Using data samples collected with the BESIII detector at the BEPCII collider, the Born cross section of e + e - to pbar{p} at 12 center-of-mass energies from 2232.4 to 3671.0 MeV is provided. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal. In addition, the ratio of electric to magnetic form factors are extracted for the data samples with larger statistics. The measured cross sections are in agreement with recent results from BaBar, improving the overall uncertainty by about 30%. The |GE/GM| ratios are close to unity and consistent with BaBar results in the same q2 region.
5. Two-photon excitation cross section in light and intermediate atoms in frozen-core LS-coupling approximation
NASA Technical Reports Server (NTRS)
Omidvar, K.
1980-01-01
Using the method of explicit summation over the intermediate states two-photon absorption cross sections in light and intermediate atoms based on the simplistic frozen-core approximation and LS coupling have been formulated. Formulas for the cross section in terms of integrals over radial wave functions are given. Two selection rules, one exact and one approximate, valid within the stated approximations are derived. The formulas are applied to two-photon absorptions in nitrogen, oxygen, and chlorine. In evaluating the radial integrals, for low-lying levels, the Hartree-Fock wave functions, and for high-lying levels, hydrogenic wave functions obtained by the quantum-defect method have been used. A relationship between the cross section and the oscillator strengths is derived.
6. Brominated 7-hydroxycoumarin-4-ylmethyls: Photolabile protecting groups with biologically useful cross-sections for two photon photolysis
PubMed Central
Furuta, Toshiaki; Wang, Samuel S.-H.; Dantzker, Jami L.; Dore, Timothy M.; Bybee, Wendy J.; Callaway, Edward M.; Denk, Winfried; Tsien, Roger Y.
1999-01-01
Photochemical release (uncaging) of bioactive messengers with three-dimensional spatial resolution in light-scattering media would be greatly facilitated if the photolysis could be powered by pairs of IR photons rather than the customary single UV photons. The quadratic dependence on light intensity would confine the photolysis to the focus point of the laser, and the longer wavelengths would be much less affected by scattering. However, previous caged messengers have had very small cross sections for two-photon excitation in the IR region. We now show that brominated 7-hydroxycoumarin-4-ylmethyl esters and carbamates efficiently release carboxylates and amines on photolysis, with one- and two-photon cross sections up to one or two orders of magnitude better than previously available. These advantages are demonstrated on neurons in brain slices from rat cortex and hippocampus excited by glutamate uncaged from N-(6-bromo-7-hydroxycoumarin-4-ylmethoxycarbonyl)-l-glutamate (Bhc-glu). Conventional UV photolysis of Bhc-glu requires less than one-fifth the intensities needed by one of the best previous caged glutamates, γ-(α-carboxy-2-nitrobenzyl)-l-glutamate (CNB-glu). Two-photon photolysis with raster-scanned femtosecond IR pulses gives the first three-dimensionally resolved maps of the glutamate sensitivity of neurons in intact slices. Bhc-glu and analogs should allow more efficient and three-dimensionally localized uncaging and photocleavage, not only in cell biology and neurobiology but also in many technological applications. PMID:9990000
7. Chemiluminescence from the Ca*(/sup 3/P) + SF/sub 6/ reaction: absolute cross section, photon yields, and electronic branching
SciTech Connect
Verdasco, E.; Rabanos, V.S.; Aoiz, F.J.; Urena, A.G.
1987-04-09
A study of the chemiluminescence under single-collision conditions of the reaction of the metastable Ca(4s4p /sup 3/P/sup 0/) of atomic calcium with SF/sup 6/ is presented. Chemiluminescence cross sections and photon yields for production of various CaF (A,B) band systems are also reported. The observed electronic branching ratio sigma/sub A//sigma/sub B/ is 4.77, and a comparison with several statistical model calculations is also discussed.
8. Measurement of the inclusive isolated prompt photon cross section in pp collisions at √{s}=8 TeV with the ATLAS detector
2016-08-01
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of √{s}=8 TeV is presented. The measurement covers the pseudorapidity ranges | η γ | < 1 .37 and 1 .56 ≤ | η γ | < 2 .37 in the transverse energy range 25 < E T γ < 1500 GeV. The results are based on an integrated luminosity of 20.2 fb-1, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on the observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate. The measured cross sections are compared with leading-order and next-to-leading order perturbative QCD calculations and are found to be in a good agreement over ten orders of magnitude. [Figure not available: see fulltext.
9. Measurement of the inclusive isolated prompt photon cross section in pp collisions at $$\\sqrt{s}=8$$ TeV with the ATLAS detector
DOE PAGES
Aad, G.; Abbott, B.; Abdallah, J.; ...
2016-08-01
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of √s = 8 TeV is presented. The measurement covers the pseudorapidity ranges |ηγ | < 1.37 and 1.56 ≤ |ηγ | < 2.37 in the transverse energy range 25 < ETγ < 1500 GeV. The results are based on an integrated luminosity of 20.2 fb–1, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on themore » observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate. In conclusion, the measured cross sections are compared with leading-order and next-to-leading order perturbative QCD calculations and are found to be in a good agreement over ten orders of magnitude.« less
10. Measurement of the inclusive isolated prompt photon cross section in pp collisions at $\\sqrt{s}=8$ TeV with the ATLAS detector
SciTech Connect
2016-08-01
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of √s = 8 TeV is presented. The measurement covers the pseudorapidity ranges |ηγ | < 1.37 and 1.56 ≤ |ηγ | < 2.37 in the transverse energy range 25 < ETγ < 1500 GeV. The results are based on an integrated luminosity of 20.2 fb–1, recorded by the ATLAS detector at the LHC. Photon candidates are identified by combining information from the calorimeters and the inner tracker. The background is subtracted using a data-driven technique, based on the observed calorimeter shower-shape variables and the deposition of hadronic energy in a narrow cone around the photon candidate. In conclusion, the measured cross sections are compared with leading-order and next-to-leading order perturbative QCD calculations and are found to be in a good agreement over ten orders of magnitude.
11. Effects of the plasma profiles on photon and pair production in ultrahigh intensity laser solid interaction
SciTech Connect
Tian, Y. X.; Jin, X. L. Yan, W. Z.; Li, J. Q.; Li, B.; Yu, J. Q.
2015-12-15
The model of photon and pair production in strong field quantum electrodynamics is implemented into our 1D3V particle-in-cell code with Monte Carlo algorithm. Using this code, the evolution of the particles in ultrahigh intensity laser (∼10{sup 23} W/cm{sup 2}) interaction with aluminum foil target is observed. Four different initial plasma profiles are considered in the simulations. The effects of initial plasma profiles on photon and pair production, energy spectra, and energy evolution are analyzed. The results imply that one can set an optimal initial plasma profile to obtain the desired photon distributions.
12. Quantum computation based on photonic systems with two degrees of freedom assisted by the weak cross-Kerr nonlinearity
PubMed Central
Luo, Ming-Xing; Li, Hui-Ran; Lai, Hong
2016-01-01
Most of previous quantum computations only take use of one degree of freedom (DoF) of photons. An experimental system may possess various DoFs simultaneously. In this paper, with the weak cross-Kerr nonlinearity, we investigate the parallel quantum computation dependent on photonic systems with two DoFs. We construct nearly deterministic controlled-not (CNOT) gates operating on the polarization spatial DoFs of the two-photon or one-photon system. These CNOT gates show that two photonic DoFs can be encoded as independent qubits without auxiliary DoF in theory. Only the coherent states are required. Thus one half of quantum simulation resources may be saved in quantum applications if more complicated circuits are involved. Hence, one may trade off the implementation complexity and simulation resources by using different photonic systems. These CNOT gates are also used to complete various applications including the quantum teleportation and quantum superdense coding. PMID:27424767
13. Photon and dilepton production in high energy heavy ion collisions
SciTech Connect
Sakaguchi, Takao
2015-05-07
The recent results on direct photons and dileptons in high energy heavy ion collisions, obtained particularly at RHIC and LHC are reviewed. The results are new not only in terms of the probes, but also in terms of the precision. We shall discuss the physics learned from the results.
14. Top Quark Pair Production Cross Section at the Tevatron
SciTech Connect
Peters, Reinhild Yvonne
2015-09-25
The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark production cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.
15. Power-efficient production of photon pairs in a tapered chalcogenide microwire
SciTech Connect
Meyer-Scott, Evan Dot, Audrey; Ahmad, Raja; Li, Lizhu; Rochette, Martin; Jennewein, Thomas
2015-02-23
Using tapered fibers of As{sub 2}Se{sub 3} chalcogenide glass, we produce photon pairs at telecommunication wavelengths with low pump powers. We found maximum coincidences-to-accidentals ratios of 2.13 ± 0.07 for degenerate pumping with 3.2 μW average power, and 1.33 ± 0.03 for non-degenerate pumping with 1.0 μW and 1.5 μW average power of the two pumps. Our results show that the ultrahigh nonlinearity in these microwires could allow single-photon pumping to produce photon pairs, enabling the production of large entangled states, heralding of single photons after lossy transmission, and photonic quantum information processing with nonlinear optics.
16. CT14QED parton distribution functions from isolated photon production in deep inelastic scattering
Schmidt, Carl; Pumplin, Jon; Stump, Daniel; Yuan, C.-P.
2016-06-01
We describe the implementation of quantum electrodynamic (QED) evolution at leading order (LO) along with quantum chromodynamic (QCD) evolution at next-to-leading order (NLO) in the CTEQ-TEA global analysis package. The inelastic contribution to the photon parton distribution function (PDF) is described by a two-parameter ansatz, coming from radiation off the valence quarks, and based on the CT14 NLO PDFs. Setting the two parameters to be equal allows us to completely specify the inelastic photon PDF in terms of the inelastic momentum fraction carried by the photon, p0γ, at the initial scale Q0=1.295 GeV . We obtain constraints on the photon PDF by comparing with ZEUS data [S. Chekanov et al. (ZEUS Collaboration), Phys. Lett. B 687, 16 (2010)] on the production of isolated photons in deep inelastic scattering, e p →e γ +X . For this comparison we present a new perturbative calculation of the process that consistently combines the photon-initiated contribution with the quark-initiated contribution. Comparison with the data allows us to put a constraint at the 90% confidence level of p0γ≲0.14 % for the inelastic photon PDF at the initial scale of Q0=1.295 GeV in the one-parameter radiative ansatz. The resulting inelastic CT14QED PDFs will be made available to the public. In addition, we also provide CT14QEDinc PDFs, in which the inclusive photon PDF at the scale Q0 is defined by the sum of the inelastic photon PDF and the elastic photon distribution obtained from the equivalent photon approximation.
17. Entangled'' free-induction decay in CdS crystal under two-photon excitation by two crossed laser beams
Leontiev, A. V.; Lobkov, V. S.; Mitrofanova, T. G.; Shmelyov, A. G.; Samartsev, V. V.
2012-09-01
A new method of two-photon excitation of femtosecond signals of entangled'' free induction decay (EFID) by two crossed 790-nm laser beams in a CdS crystal at room temperature has been realized for the first time. This entangled'' (through the wave vectors) coherent response appears only in the case when the photons involved to the process of two-photon excitation of the sample belong to the different laser beams. This technique allows one to separate the EFID signal from the exciting femtosecond pulses and to vary the response wavelength by varying the angle between their wave vectors. The most optimal case occurs when the angle between the wave vectors of exciting pulses as well as the angle between each of these wave vectors and that of the response is equal to 60°.
18. Measurements of partial cross sections and photoelectron angular distributions for the photodetachment of Fe- and Cu- at visible photon wavelengths
Covington, A. M.; Duvvuri, Srividya S.; Emmons, E. D.; Kraus, R. G.; Williams, W. W.; Thompson, J. S.; Calabrese, D.; Carpenter, D. L.; Collier, R. D.; Kvale, T. J.; Davis, V. T.
2007-02-01
Photodetachment cross sections and the angular distributions of photoelectrons produced by the single-photon detachment of the transition metal negative ions Fe- and Cu- have been measured at four discrete photon wavelengths ranging from 457.9 to 647.1nm (2.71-1.92eV) using a crossed-beams laser photodetachment electron spectrometry (LPES) apparatus. Photodetachment cross sections were determined by comparing the photoelectron yields from the photodetachment of Fe- to those of Cu- and C- , which have known absolute photodetachment cross sections. Using the measured photodetachment cross sections, radiative electron attachment cross sections were calculated using the principle of detailed balance. Angular distributions were determined by measurements of laboratory frame, angle-, and energy-resolved photoelectrons as a function of the angle between the linear laser polarization vector and the momentum vector of the collected photoelectrons. Values of the asymmetry parameter have been determined by nonlinear least-squares fits to these angular distributions. The measured asymmetry parameters are compared to predictions of photodetachment models including Cooper and Zare’s dipole approximation theory [J. Cooper and R. N. Zare, J. Chem. Phys. 48, 942 (1968)], and the angular momentum transfer theory developed by Fano and Dill [Phys. Rev. A 6, 185 (1972)].
19. Pion and photon production in heavy ion collisions
SciTech Connect
Gabor,D.
2008-03-16
Measurement of neutral pions and direct photons are closely connected experimentally, on the other hand they probe quite different aspects of relativistic heavy ion collisions. In this short review of the {pi}{sup 0} results from the PHENIX experiment at RHIC our focus is on the {phi}-integrated nuclear modification factor, its energy and system size dependence, and the impact of these results on parton energy loss models. We also discuss the current status of high p{sub T} and thermal direct photon measurements both in p+p and Au+Au collisions. Recognizing the advantages of measuring not only the 'signal', but also all the 'references' needed for proper interpretation in the same experiments (with same or similar systematics) we argue that RHIC should regularly include d+A and even d+d collisions into its system size and energy scan.
20. Deterministic Production of Photon Number States via Quantum Feedback Control
Geremia, J. M.
2006-05-01
It is well-known that measurements reduce the state of a quantum system, at least approximately, to an eigenstate of the operator associated with the physical property being measured. Here, we employ a continuous measurement of cavity photon number to achieve a robust, nondestructively verifiable procedure for preparing number states of an optical cavity mode. Such Fock states are highly sought after for the enabling role they play in quantum computing, networking and precision metrology. Furthermore, we demonstrate that the particular Fock state produced in each application of the continuous photon number measurement can be controlled using techniques from real-time quantum feedback control. The result of the feedback- stabilized measurement is a deterministic source of (nearly ideal) cavity Fock states. An analysis of feedback stability and the experimental viability of a quantum optical implementation currently underway at the University of New Mexico will be presented.
1. On the photon production in nucleus-nucleus collisions at high energy
Tarasov, Y. A.; Antonenko, V. G.
1995-03-01
A modified Landau hydrodynamical model is applied to study hard thermal photon production in central heavy-ion collisions at LHC, RHIC and SPS energies. It is shown that the phase transition from quark-gluon plasma into hadrons in consequence of the thermodynamical expansion is close to the second order phase transition if a resonance production is taken into account. Hard direct photon emission is also investigated with consideration of nuclear shadowing effect on structure function of quarks and gluons. Also ππ photon background is investigated. It is demonstrated that at the LHC energy photon yield from the quark-gluon plasma in the photon transversal momentum k ⊥ range from 5 to 25 GeV/c exceeds both the background and the direct photon yield. This conclusion may be important for the quark-gluon plasma diagnostic aims. It is also shown that for the LHC energy the thermal photon yield in the present model essentially exceeds this yield obtained in the Bjorken scaling model.
2. Measurement of the inclusive isolated prompt photon cross section in $p\\bar{p}$ collisions at $\\sqrt{s}=$1.96~TeV, using the full CDF data sample
SciTech Connect
Luca, Alessandra
2016-01-01
The measurement of the cross section for the inclusive production of isolated prompt photons in proton-antiproton collisions at $\\sqrt{s}$=1.96~TeV is presented. The data set corresponds to an integrated luminosity of 9.5~fb$^{-1}$, collected with the Collider Detector at Fermilab in Run~II. The measurement is performed as a function of the photon transverse energy ($E_T^{\\gamma}$) covering the range of 30~GeV$< E_T^{\\gamma} <$500~GeV in the pseudorapidity region $|\\eta^{\\gamma}|<$1.0. To reduce the background coming from the decays of $\\pi^0$'s, $\\eta$'s and other hadrons, photons are required to be isolated in the calorimeter. The output distributions of an Artificial Neural Network are exploited to estimate the remaining contamination from jets faking isolated photons. Results are compared to leading-order and next-to-leading-order perturbative QCD calculations.
3. Two-color interference effect involving three-photon atomic excitation and four-wave mixing in crossed laser beams
SciTech Connect
Peet, V.
2007-09-15
Through multiphoton ionization measurements, the polarization effects in destructive quantum interference under three-photon resonant excitation have been studied. Recent observations [V. Peet, Phys. Rev. A 74, 033406 (2006)] have indicated that contrary to the well-known pattern of a total suppression of resonance excitation, the destructive interference becomes incomplete if three-photon transition is driven by crossed beams with orthogonal polarization planes. These observations have been tested for a more general case of two-color excitation and very similar polarization-dependent anomalies in the interference character have been registered. It has been shown that the destructive interference is modified and the resonance excitation does occur if two crossed laser beams have opposite circular polarizations. The pressure-induced evolution of the uncanceled ionization peaks has the ratio of blue shift to width close to 0.5 exactly as it is known for resonance ionization peaks registered under excitation by counterpropagating laser beams.
4. Code System for Producing Pointwise and Multigroup Neutron and Photon Cross Sections from ENDF/B Data.
SciTech Connect
MACFARLANE, ROBERT E.
1996-12-19
Version 03 The NJOY nuclear data processing system is a comprehensive computer code system for producing pointwise and multigroup cross sections and related quantities from ENDF/B evaluated nuclear data in the ENDF format, including the latest US library, ENDF/B-VI. The NJOY code works with neutrons, photons, and charged particles and produces libraries for a wide variety of particle transport and reactor analysis codes.
5. Calculation of Nuclear Particles Production at High-Energy Photon Beams from a Linac Operating at 6, 10 and 15 MV.
PubMed
Marchesini, Renato; Bettega, Daniela; Calzolari, Paola; Pignoli, Emanuele
2016-08-13
Production of photonuclear particles in a tissue-equivalent medium has been calculated for linacs at 6, 10 and 15 MV from Varian TrueBeam. Based on the knowledge of bremsstrahlung fluence spectra and linac photon beam parameters, numerical integration was performed on the cross sections for photoparticle production of the constituent elements of tissue ((2)H,(12)C,(13)C,(16)O,(17)O,(18)O,(14)N,(15)N). At 15 MV, at the depth of photon maximum dose, the total absorbed dose due to neutrons, protons, alphas and residual nuclei from photon reactions in tissue (5.5E-05 Gy per Gy of photons) is comparable to that due to neutrons from accelerator head. Results reasonably agree with data reported in the literature using Monte Carlo models simulating linac head components. This work suggests a simple method to estimate the dose contributed by the photon-induced nuclear particles for high-energy photon beams produced by linacs in use, as it might be relevant for late stochastic effects.
6. A practical guide to event generation for prompt photon production with Sherpa
Siegert, Frank
2017-04-01
The production of prompt photons is one of the most relevant scattering processes studied at hadron–hadron colliders in recent years. This article will give an overview of the different approaches used to simulate prompt photon production in the Sherpa event generator framework. Special emphasis is placed on a complete simulation of this process including fragmentation configurations. As a novel application a merged simulation of γ γ and γ γ +jet production at NLO accuracy is presented and compared to measurements from the ATLAS experiment.
7. Study of photon emission by electron capture during solar nuclei acceleration. 3: Photon production evaluations
NASA Technical Reports Server (NTRS)
Perez-Peraza, J.; Alvarez, M.; Gallegos, A.
1985-01-01
Lower limits of photon fluxes were evaluated from electron capture during acceleration in solar flares, because the arbitrary q sub c asterisk assumed in this work evolves very slow with velocity, probably much more slowly than the physical actual situation: in fact, more emission is expected toward the IR region. Nevertheless the authors claim to show that the factibility of sounding acceleration processes, charge evolution processes and physical parameters of the source itself, by the observational analysis of this kind of emissions. For instance, it would be interesting to search observationally, for the predicted flux and energy drift of F sub e ions interacting with the atomic 0 and F sub e of the source matter, or, even more feasible for the X-ray lines at 4.2 keV and 2.624 + 0.003 KeV from Fe and S ions in ionized Fe at T = 10 to the 7th power K respectively, the 418 + or - 2 eV and 20 + or - 4 eV lines of Fe and S in ionized Fe at 5 x 10 to the 6th power K, which are predicted from Fermi acceleration.
8. Ratiometric Visualization of NO/H2S Cross-Talk in Living Cells and Tissues Using a Nitroxyl-Responsive Two-Photon Fluorescence Probe.
PubMed
Zhou, Yibo; Zhang, Xiufang; Yang, Sheng; Li, Yuan; Qing, Zhihe; Zheng, Jing; Li, Jishan; Yang, Ronghua
2017-03-27
It is of scientific significance to explore the intricate relationship between two crucial gasotransmitters nitric oxide (NO) and hydrogen sulfide (H2S), because they exert similar and interdependent biological actions within the living organisms. Nevertheless, visualization of the NO/H2S crosstalk using effective molecular imaging tools remains challenging. To address this issue, and given that nitroxyl (HNO) has been implicated as the interdependent production of NO and H2S via a network of cascading chemical reactions, we herein design a ratiometric two-photon fluorescent probe for HNO, termed TP-Rho-HNO, which consists of benzo[h]chromene-rhodol scaffold as two-photon energy transfer cassette with phosphine moiety as specific HNO recognition unit. The newly proposed probe has been successfully applied in ratiometric two-photon bioimaging of endogenous HNO derived from NO and H2S interaction in the human umbilical vein cells (HUVECs) and as well as in rat brain tissues. Intriguingly, the imaging results consistently demonstrate that the mutually dependent upgeneration of H2S and NO are present in living biosystems, indicating that this molecular probe would provide a powerful approach to elucidate the chemical foundation for the anfractuous cross-talk between the NO and H2S signaling pathways in biology.
9. Modified TAROT for cross-selling personal financial products
Tee, Ya-Mei; LEE, Lai-Soon; LEE, Chew-Ging; SEOW, Hsin-Vonn
2014-09-01
The Top Application characteristics Remainder Offer characteristics Tree (TAROT) was first introduced in 2007. This is a modified Classification and Regression Trees (CART) used to help decide which question(s) to ask potential applicants to customise an offer of a personal financial product so that it would have a high probability of take up. In this piece of work the authors are presenting, they have further modified the TAROT to cross TAROT, using its properties and modeling steps to deal with the issue of cross-selling. Since the bank already has ready customers, it would be ideal to cross-sell the financial products seeing that one can ask one (or more) further question(s) based on the initial offer to identify and customise another financial product to offer.
10. Comparison of photon and hadron induced production of ρ0 mesons in the energy range of 65 to 175 GeV
Apsimon, R. J.; Atkinson, M.; Baake, M.; Bagdasarian, L. S.; Barberis, D.; Brodbeck, T. J.; Brook, N.; Charity, T.; Clegg, A. B.; Coyle, P.; Danaher, S.; Danagulian, S.; Davenport, M.; Dickinson, B.; Diekmann, B.; Donnachie, A.; Doyle, A. T.; Eades, J.; Ellison, R. J.; Fiedler, F.; Flower, P. S.; Foster, J. M.; Galbraith, W.; Galumian, P. I.; Gapp, C.; Gebert, F.; Hallewell, G.; Heinloth, K.; Henderson, R. C. W.; Hickman, M. T.; Hoeger, K. C.; Hofmann, R. P.; Holzkamp, A.; Holzkamp, S.; Hughes-Jones, R. E.; Ibbotson, M.; Jakob, H. P.; Joseph, D.; Keemer, N. R.; Kingler, J.; Körsgen, G.; Kolya, S. D.; Lafferty, G. D.; McCann, H.; McClatchey, R.; McManus, C.; Mercer, D.; Morris, J. A. G.; Morris, J. V.; Newton, D.; O'Connor, A.; Oedingen, R.; Oganesian, A. G.; Ottewell, P. J.; Paterson, C. N.; Paul, E.; Raid, D.; Rotscheidt, H.; Sharp, P. H.; Soeldner-Rembold, S.; Thacker, N. A.; Thompson, L.; Thompson, R. J.; Waterhouse, J.; Weigend, A. S.; Wilson, G. W.
1992-12-01
The inclusive production of ρ0 mesons was measured in γ p and h ± p collisions at beam energies of 65 GeV≦ E γ≦175 GeV and E h =80, 140 GeV, respectively, where h is π or K. Cross sections were determined for all beams and energies as functions of x F (-0.1≦ x F≦1.0), p T (0≦ p T≦3.5 GeV/c) and the polar decay angle of the ρ0 by fitting the ρ0 signal in π+π- mass distributions. The ρ0 line shape is found to be distorted from a pure Breit-Wigner distribution throughout most of the x F- p T plane for both photon and hadron beams and a simple explanation is suggested. Throughout the paper emphasis is put on the comparison of photon and hadron beam data. The comparison of cross sections of γ p and hp data provides a measure of the Vector Meson Dominance factor throughout the x F- p T range of the ρ0. The ρ0 production at low p T can be described for both photon and hadron beams by a triple regge model at large x F. Similarly central production is well described by the quark-antiquark fusion model. At large p T there is an excess of ρ0 photoproduction which is consistent with the expected onset of pointlike photon interactions.
11. Photon-photon collisions
SciTech Connect
Burke, D.L.
1982-10-01
Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.
12. Exclusive photon-photon production of muon pairs in proton-proton collisions at sqrt(s) = 7 TeV
SciTech Connect
Chatrchyan, Serguei; Khachatryan, Vardan; Sirunyan, Albert M.; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; /Yerevan Phys. Inst. /Vienna, OAW /Minsk, High Energy Phys. Ctr. /Antwerp U., WISINF /Vrije U., Brussels /Brussels U. /Gent U. /Louvain U. /UMH, Mons /Rio de Janeiro, CBPF /Rio de Janeiro State U.
2011-11-01
A measurement of the exclusive two-photon production of muon pairs in proton-proton collisions at {radical}s = 7 TeV, pp {yields} p{mu}{sup +}{mu}{sup -}p, is reported using data corresponding to an integrated luminosity of 40 pb{sup -1}. For muon pairs with invariant mass greater than 11.5 GeV, transverse momentum p{sub T}({mu}) > 4 GeV and pseudorapidity |{eta}({mu})| < 2.1, a fit to the dimuon p{sub T}({mu}{sup +}{mu}{sup -}) distribution results in a measured cross section of {sigma}(p {yields} p{mu}{sup +}{mu}{sup -}) = 3.38{sub -0.55}{sup +0.58}(stat.) {+-} 0.16(syst.) {+-} 0.14(lumi.) pb, consistent with the theoretical prediction evaluated with the event generator LPAIR. The ratio to the predicted cross section is 0.83{sub -0.13}{sup +0.14}(stat.) {+-} 0.04(syst.) {+-} 0.03(lumi.). The characteristic distributions of the muon pairs produced via {gamma}{gamma} fusion, such as the muon acoplanarity, the muon pair invariant mass and transverse momentum agree with those from the theory.
13. Search for Double Higgs Production in the Final State with Two Photons and Two Bottom Quarks at the CMS Detector
Hebda, Philip Robert
A search for the production of Higgs pairs in the decay channel with two photons and two bottom quarks is reported for both resonant and nonresonant cases. The data corresponds to an integrated luminosity of 19.7 /fb of proton-proton collisions at a center-of-mass energy of 8 TeV collected by the CMS detector at the CERN Large Hardron Collider. The candidate events are selected by requiring two photons and two jets and are classified according to the number of jets tagged as coming from the hadronization of a bottom quark. The search for resonance production of two Higgs bosons through a new particle as hypothesized in extensions to the Standard Model involving a Radion or KK-graviton from models with warped extra dimensions or involving a heavy Higgs from models with supersymmetry, is performed on the resonant mass range from 260 GeV to 1100 GeV. The search for Standard Model nonresonant production of two Higgs bosons is performed; in addition a theoretical framework is explored for the analysis of anomalous values of the couplings tt¯H, HHH, and tt¯HH. The observations are consistent with background expectations. Upper limits at the 95% confidence level are extracted on the production cross section of resonant and SM nonresonant production. In particular, the Radion with a vacuum expectation of 1 TeV is observed (expected) to be excluded with masses below 0.97 TeV (0.88 TeV), while the analysis is not sensitive to the Radion with a vacuum expectation of 3 TeV. The nonresonant double Higgs cross section is observed (expected) to be excluded at 1.91 fb (1.59 fb) or 72.9 (60.7) times the NNLO Standard Model value.
14. Vectorial laws of refraction and reflection using the cross product and dot product.
PubMed
Tkaczyk, Eric R
2012-03-01
We demonstrate that published vectorial laws of reflection and refraction of light based solely on the cross product do not, in general, uniquely determine the direction of the reflected and refracted waves without additional information. This is because the cross product does not have a unique inverse operation, which is explained in this Letter in linear algebra terms. However, a vector is in fact uniquely determined if both the cross product (vector product) and dot product (scalar product) with a known vector are specified, which can be written as a single equation with a left-invertible matrix. It is thus possible to amend the vectorial laws of reflection and refraction to incorporate both the cross and dot products for a complete specification with unique solution. This enables highly efficient, unambiguous computation of reflected and refracted wave vectors from the incident wave and surface normal.
15. Chiral symmetry breaking and confinement effects on dilepton and photon production around Tc
Satow, Daisuke; Weise, Wolfram
2015-09-01
Production rates of dileptons and photons from the quark-gluon (QGP) phase are calculated taking into account effects of confinement and spontaneous chiral symmetry breaking (χ SB ) not far from the transition temperature Tc. We find that the production rates of dileptons with large momenta and of photons originating from the QGP around Tc are suppressed by the χ SB effect. We also discuss to what extent information about details of the chiral transition, such as its characteristic temperature range and the steepness of the crossover, are reflected in these quantities.
16. Synthesis, crystals of centrosymmetric triphenylamine chromophores bearing prodigious two-photon absorption cross-section and biological imaging.
PubMed
Wang, Shichao; Xu, Shasha; Wang, Yiming; Tian, Xiaohe; Zhang, Yujin; Wang, Chuankui; Wu, Jieying; Yang, Jiaxiang; Tian, Yupeng
2017-02-15
Two centrosymmetric D-π-D type triphenylamine chromophores with long π-conjugated bridge and strong electron-donating moiety were designed, synthesized and fully characterized. The crystal analysis revealed that multiple CH⋯π interactions existed in two chromophores, which played a crucial role in generating molecular 1D chains and 2D layers structures. Linear and nonlinear optical properties of the chromophores were systematically investigated with the aid of theoretical calculations. Two chromophores both exhibited intense and wide-dispersed one-photon/two-photon excited fluorescence, bear prodigious 2PA cross section (δ). Especially for Dye2, with ethyoxyl groups, displayed the strong 2PA activity, large cross-sections (δmax>16,000GM) and high NLO efficiency (δmax/MW>16GM/(g·mol)) in the range of 680-830nm in DMF. In addition, one- and two-photon fluorescence microscopy images of HepG2 cells incubated with Dye2 were obtained and found that Dye2 could effectively uptake toward living cells and display a uniformly localized in cytosolic space.
17. Synthesis, crystals of centrosymmetric triphenylamine chromophores bearing prodigious two-photon absorption cross-section and biological imaging
Wang, Shichao; Xu, Shasha; Wang, Yiming; Tian, Xiaohe; Zhang, Yujin; Wang, Chuankui; Wu, Jieying; Yang, Jiaxiang; Tian, Yupeng
2017-02-01
Two centrosymmetric D-π-D type triphenylamine chromophores with long π-conjugated bridge and strong electron-donating moiety were designed, synthesized and fully characterized. The crystal analysis revealed that multiple Csbnd H ⋯ π interactions existed in two chromophores, which played a crucial role in generating molecular 1D chains and 2D layers structures. Linear and nonlinear optical properties of the chromophores were systematically investigated with the aid of theoretical calculations. Two chromophores both exhibited intense and wide-dispersed one-photon/two-photon excited fluorescence, bear prodigious 2PA cross section (δ). Especially for Dye2, with ethyoxyl groups, displayed the strong 2PA activity, large cross-sections (δmax > 16,000 GM) and high NLO efficiency (δmax/MW > 16 GM/(g·mol)) in the range of 680-830 nm in DMF. In addition, one- and two-photon fluorescence microscopy images of HepG2 cells incubated with Dye2 were obtained and found that Dye2 could effectively uptake toward living cells and display a uniformly localized in cytosolic space.
18. Cross-talk characterization of dense single-photon avalanche diode arrays in CMOS 150-nm technology
Xu, Hesong; Pancheri, Lucio; C. Braga, Leo H.; Betta, Gian-Franco Dalla; Stoppa, David
2016-06-01
Cross-talk characterization results of high-fill-factor single-photon avalanche diode (SPAD) arrays in CMOS 150-nm technology are reported and discussed. Three different SPAD structures were designed with two different sizes (15.6 and 25.6 μm pitch) and three guard ring widths (0.6, 1.1, and 1.6 μm). Each SPAD was implemented in an array, composed of 25 (5×5) devices, which can be separately activated. Measurement results show that the average cross-talk probability is well below 1% for the shallow-junction SPAD structure with 15.6 μm pitch and 39.9% fill factor, and 1.45% for the structure with 25.6 μm pitch and 60.6% fill factor. An increase of cross-talk probability with the excess bias voltage is observed.
19. Photon Production from Proton-Antiproton Collisions at SQRT.S = 1.8TEV
Carter, Thomas Gordon
1990-01-01
The first measurement of low energy photon production from pp collisions at sqrt{s} = 1.8TeV is presented. The transverse momentum spectrum for photons is measured between 260 and 1500MeV/c. The < P_{t}> between those limits is 511 +/- 11MeV/c. The absolute photon production rate in the range P_{t} = 0-1500MeV/c for -0.48 >=q eta >=q 0.97 is found to be {dN _gammaover deta} = 3.44 +/- 0.15 +/- 0.34. The photon to charged pi ratio is measured in this range and found to be 1.40 +/- 0.07 +/- 0.20. For values of average charged particle multiplicity between 20 and 123, the value of < P_ {t}> varies linearly between 487MeV/c and 560MeV/c, the absolute production rate varies linearly between 1.55 and 10.1 and the photon to charge pi ratio remains constant. The eta to pi^0 ratio for the data sample is determined to be 0.33 +/- 0.19.
20. Cross Modulation of Two Laser Beams at the Individual-Photon Level
DTIC Science & Technology
2014-09-12
medium, such that the photons travel as slow-light polaritons [15,25,26], whose atomic excitation component can block the transmission of another light...through the ensemble, traveling in the medium as slow-light polaritons , a superposition of a photon and a collective atomic excitation to the state...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 slow-light polariton , the polariton’s atomic component in state jci reduces
1. Photon-photon collisions
SciTech Connect
Brodsky, S.J.
1988-07-01
Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.
2. Time-dependent configuration-interaction-singles calculation of the 5 p -subshell two-photon ionization cross section in xenon
Karamatskou, Antonia; Santra, Robin
2017-01-01
The 5 p two-photon ionization cross section of xenon in the photon-energy range below the one-photon ionization threshold is calculated within the time-dependent configuration-interaction-singles (TDCIS) method. The TDCIS calculations are compared to random-phase-approximation calculations [Wendin et al., J. Opt. Soc. Am. B 4, 833 (1987), 10.1364/JOSAB.4.000833] and are found to reproduce the energy positions of the intermediate Rydberg states reasonably well. The effect of interchannel coupling is also investigated and found to change the cross section of the 5 p shell only slightly compared to the intrachannel case.
3. Top quark pair production cross section at the Tevatron
SciTech Connect
2008-04-01
Top quark pair production cross section has been measured at the Tevatron by CDF and D0 collaborations using different channels and methods, in order to test standard model predictions, and to search for new physics hints affecting the t{bar t} production mechanism or decay. Measurements are carried out with an integrated luminosity of 1.0 to 2.0 fb{sup -1}, and are found to be consistent with standard model expectations.
4. Abstracts of computer programs and data libraries pertaining to photon production data
SciTech Connect
White, J.E.; Manneschmidt, J.B.; Finch, S.Y.; Dickens, J.K.
1998-06-01
Abstracts, or descriptions, of computer programs and data libraries pertaining to Photon Production Data (Measurements, Evaluations and Calculations) maintained in the collections of the Radiation Safety Information Computational Center, Oak Ridge, Tennessee USA and at the OECD/NEA Data Bank, Paris, are collected in this document.
5. Stopping powers and cross sections due to two-photon processes in relativistic nucleus-nucleus collision
NASA Technical Reports Server (NTRS)
Cheung, Wang K.; Norbury, John W.
1992-01-01
The radiation dose received from high energy galactic cosmic rays (GCR) is a limiting factor in the design of long duration space flights and the building of lunar and martian habitats. It is of vital importance to have an accurate understanding of the interactions of GCR in order to assess the radiation environment that the astronauts will be exposed to. Although previous studies have concentrated on the strong interaction process in GCR, there are also very large effects due to electromagnetic (EM) interactions. In this report we describe our first efforts at understanding these EM production processes due to two-photon collisions. More specifically, we shall consider particle production processes in relativistic heavy ion collisions (RHICs) through two-photon exchange.
6. Geolocating Individual Photons: Laying the Foundation for ICESat-2 Science Data Products
Webb, C. E.; Neumann, T.; Brenner, A. C.; Luthcke, S. B.; Robbins, J. W.; Saba, J. L.
2015-12-01
The Ice, Cloud and land Elevation Satellite-2 (ICESat-2) is NASA's next generation spaceborne laser altimeter, currently scheduled for launch in October 2017. The sole instrument onboard is the Advanced Topographic Laser Altimeter System (ATLAS), which will use a photon-counting detection method to measure range from the satellite to the Earth's surface with green (532-nm wavelength) laser light. Combining these measurements with precise knowledge of the position and orientation of the ATLAS instrument in orbit will yield elevation measurements to ±88° latitude around the globe. In this presentation, we provide an overview of the ICESat-2 data products with a particular focus on the Global Geolocated Photon Cloud. With two redundant lasers, operated one at a time, ATLAS sends laser pulses toward the Earth 10,000 times per second, and the outgoing beam is split into three pairs of two beams, to increase spatial coverage and enable determination of local surface slopes. Geolocation algorithms in the ground-based science data processing system will produce a latitude, longitude and ellipsoidal elevation for each photon that is returned to ATLAS, yielding a photon point cloud. These data will incorporate a suite of geophysical corrections, and the product will also provide a coarse surface classification (land ice, sea ice, ocean, land, inland water), along with initial signal-vs-noise discrimination. While higher-level, surface-specific science data products will provide the most precise estimates of surface elevation by aggregating the geolocated photons to reduce noise, we expect that this lower-level data product - which provides most of the inputs to the higher-level products - will be of interest to the general community.
7. Industrial-scale spray layer-by-layer assembly for production of biomimetic photonic systems.
PubMed
Krogman, K C; Cohen, R E; Hammond, P T; Rubner, M F; Wang, B N
2013-12-01
Layer-by-layer assembly is a powerful and flexible thin film process that has successfully reproduced biomimetic photonic systems such as structural colour. While most of the seminal work has been carried out using slow and ultimately unscalable immersion assembly, recent developments using spray layer-by-layer assembly provide a platform for addressing challenges to scale-up and manufacturability. A series of manufacturing systems has been developed to increase production throughput by orders of magnitude, making commercialized structural colour possible. Inspired by biomimetic photonic structures we developed and demonstrated a heat management system that relies on constructive reflection of near infrared radiation to bring about dramatic reductions in heat content.
8. Rapidity correlations and {Delta}G from prompt photon plus jet production in polarized pp collisions
SciTech Connect
Sanghyeon Chang; Claudio Coriano; L. E. Gordon
1997-09-01
A study of prompt photon plus associated jet production is performed at next-to-leading order (O({alpha}{alpha}{sub s}{sup 2})) in QCD at {radical}S=200--500 GeV, appropriate for the RHIC polarized {rvec p}{rvec p} collider experiment. Momentum correlations between the jet and photon are examined and the utility of the process as a method for constraining the size and shape of the polarized gluon density of the proton {Delta}G is examined.
9. Growth of optical-quality anthracene crystals doped with dibenzoterrylene for controlled single photon production
SciTech Connect
Major, Kyle D. Lien, Yu-Hung; Polisseni, Claudio; Grandi, Samuele; Kho, Kiang Wei; Clark, Alex S.; Hwang, J.; Hinds, E. A.
2015-08-15
Dibenzoterrylene (DBT) molecules within a crystalline anthracene matrix show promise as quantum emitters for controlled, single photon production. We present the design and construction of a chamber in which we reproducibly grow doped anthracene crystals of optical quality that are several mm across and a few μm thick. We demonstrate control of the DBT concentration over the range 6–300 parts per trillion and show that these DBT molecules are stable single-photon emitters. We interpret our data with a simple model that provides some information on the vapour pressure of DBT.
10. Measurement of the Inclusive Isolated Prompt Photon Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using the CDF Detector
SciTech Connect
Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR
2009-10-01
A measurement of the cross section for the inclusive production of isolated photons by the CDF experiment at the Fermilab Tevatron collider is presented. The measurement covers the pseudorapidity region |{eta}{sup {gamma}}| < 1.0 and the transverse energy range E{sub T}{sup {gamma}} > 30 GeV and is based on 2.5 fb{sup -1} of integrated luminosity. The sample is almost a factor of seven larger than those used for recent published results and extends the E{sub T}{sup {gamma}} coverage by 100 GeV. The result agrees with next-to-leading order perturbative QCD calculations within uncertainties over the range 50 < E{sub T}{sup {gamma}} < 400 GeV, though the energy spectrum in the data shows a steeper slope at lower E{sub T}{sup {gamma}}.
11. Measurement of the inclusive isolated prompt photon cross section in pp¯ collisions at s=1.96TeV using the CDF detector
Aaltonen, T.; Adelman, J.; González, B. Álvarez; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauer, G.; Beauchemin, P.-H.; Bedeschi, F.; Beecher, D.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.; Choudalakis, G.; Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Almenar, C. Cuenca; Cuevas, J.; Culbertson, R.; Cully, J. C.; Dagenhart, D.; Datta, M.; Davies, T.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca, C.; Demortier, L.; Deng, J.; Deninno, M.; D'Errico, M.; di Canto, A.; di Giovanni, G. P.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, T.; Dube, S.; Ebina, K.; Elagin, A.; Erbacher, R.; Errede, D.; Errede, S.; Ershaidat, N.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Genser, K.; Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; da Costa, J. Guimaraes; Gunay-Unalan, Z.; Haber, C.; Hahn, K.; Hahn, S. R.; Halkiadakis, E.; Han, B.-Y.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hartz, M.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Henderson, C.; Herndon, M.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Huffman, B. T.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussein, M.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin, P. E.; Kato, Y.; Kephart, R.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Knuteson, B.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leone, S.; Lewis, J. D.; Lin, C.-J.; Linacre, J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.; Loginov, A.; Lovas, L.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; MacQueen, D.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Mastrandrea, P.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione, A.; Mesropian, C.; Miao, T.; Mietlicki, D.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Fernandez, P. Movilla; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Nielsen, J.; Nodulman, L.; Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Osterberg, K.; Griso, S. Pagan; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramanov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Potamianos, K.; Poukhov, O.; Prokoshin, F.; Pronko, A.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Renz, M.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ, J.; Rusu, V.; Rutherford, B.; Saarikko, H.; Safonov, A.; Sakumoto, W. K.; Santi, L.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon, Y.; Shreyber, I.; Simonenko, A.; Sinervo, P.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur, R.; Soha, A.; Somalwar, S.; Sorin, V.; Spreitzer, T.; Squillacioti, P.; Stanitzki, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Tipton, P.; Ttito-Guzmán, P.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Tourneur, S.; Trovato, M.; Tsai, S.-Y.; Tu, Y.; Turini, N.; Ukegawa, F.; Uozumi, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar, R.; Vogel, M.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Weinelt, J.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wolfe, H.; Wright, T.; Wu, X.; Würthwein, F.; Xie, S.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.; Zhang, X.; Zheng, Y.; Zucchelli, S.
2009-12-01
A measurement of the cross section for the inclusive production of isolated photons by the CDF experiment at the Fermilab Tevatron collider is presented. The measurement covers the pseudorapidity region |ηγ|<1.0 and the transverse energy range ETγ>30GeV and is based on 2.5fb-1 of integrated luminosity. The sample is almost a factor of 7 larger than those used for recent published results and extends the ETγ coverage by 100 GeV. The result agrees with next-to-leading order perturbative QCD calculations within uncertainties over the range 50
12. A 32-channel photon counting module with embedded auto/cross-correlators for real-time parallel fluorescence correlation spectroscopy
SciTech Connect
Gong, S.; Labanca, I.; Rech, I.; Ghioni, M.
2014-10-15
Fluorescence correlation spectroscopy (FCS) is a well-established technique to study binding interactions or the diffusion of fluorescently labeled biomolecules in vitro and in vivo. Fast FCS experiments require parallel data acquisition and analysis which can be achieved by exploiting a multi-channel Single Photon Avalanche Diode (SPAD) array and a corresponding multi-input correlator. This paper reports a 32-channel FPGA based correlator able to perform 32 auto/cross-correlations simultaneously over a lag-time ranging from 10 ns up to 150 ms. The correlator is included in a 32 × 1 SPAD array module, providing a compact and flexible instrument for high throughput FCS experiments. However, some inherent features of SPAD arrays, namely afterpulsing and optical crosstalk effects, may introduce distortions in the measurement of auto- and cross-correlation functions. We investigated these limitations to assess their impact on the module and evaluate possible workarounds.
13. Inclusive photon production at forward rapidities in pp collisions at LHC energies with the ALICE experiment
Sudipan Dethe ALICE Collaboration
2016-04-01
Measurements of multiplicity and pseudorapidity distributions of particles produced in pp collisions are important for the study of particle production mechanisms and to obtain baseline distributions to be compared with those from heavy-ion collisions. The inclusive photon measurements (dominated by π0 decays) are complementary to the charged particle measurements. The present work focuses on the forward rapidity region with comparisons to different models such as PYTHIA and PHOJET. We report the measurements of multiplicity and pseudorapidity distributions of inclusive photons using the ALICE Photon Multiplicity Detector (PMD) at forward rapidities (2.3 < η < 3.9) in pp collisions at = 0.9, 2.76 and 7 TeV. It is observed that the photon multiplicity distributions are well described by negative binomial distributions (NBD). Multiplicity distributions are studied in terms of KNO variables for each energy. It is shown that the increase in the average photon multiplicity as a function of beam energy is compatible with both a logarithmic and power law dependence. The results are compared to different model predictions. These models reproduce experimental results at lower energy while they are not accurate at higher energies.
14. Wave-mixing interference in three-photon resonant atomic excitation with cross-polarized angled beams
SciTech Connect
Peet, V.
2006-09-15
Three-photon excitation and associated wave mixing near the 6s and 6s{sup '} resonances of xenon have been studied utilizing resonance-enhanced multiphoton ionization in angled beams with different polarizations. It has been shown that a complete cancellation of three-photon resonant atomic excitation caused by the well-known destructive wave-mixing interference occurs in s and p polarization of angled beams but distinct resonance ionization enhancement is observed when pump beams have orthogonal polarization planes. Pressure-induced evolution of the resonance ionization peak in cross-polarized beams is identical to that observed with counterpropagating beams. The reason for such resonance ionization enhancement is unknown and cannot be explained within the frame work of existing theory. The effect may result from some peculiarities of wave-mixing interference in a multilevel atomic system, where different degenerate magnetic sublevels of the upper atomic state and multiple interfering excitation processes are involved. Another possibility is that the resonance ionization enhancement results from a process where weak counterpropagating light is generated within the excitation region of cross-polarized angled beams.
15. Medium effect on the photon production in ultrarelativisitc heavy-ion collisions
Song, Chung-Sik; Fai, George
1998-04-01
The effect of in-medium vector and axial vector meson masses on the photon production in heavy-ion collisions has been studied. We assume that the effective mass of a vector meson in hot nuclear matter decreases while that of an axial-vector meson is given by the Weinberg mass formula, m_a_1=√2m_ρ (Phys. Rev. Lett. 18, 507 (1967)). We find that the production rate increases with reduced vector and axial vector meson masses and is enhanced by an order of magnitude at T=160 MeV with m_ρ=330 MeV, compared to the result obtained with free mass. Assuming a hydrodynamic evolution of the system we estimate the effect of the reduced masses on the photon production in nucleus-nucleus collisions. The result has been compared with experimental data obtained from WA80/WA98 collaboration (Phys. Rev. Lett. 76, 3506 (1996).).
16. Top Quark Production Cross Section at the Tevatron
SciTech Connect
Shabalina, E.; /Chicago U.
2006-05-01
An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb{sup -1} up to 760 pb{sup -1}.
17. Faking ordinary photons by displaced dark photon decays
Tsai, Yuhsin; Wang, Lian-Tao; Zhao, Yue
2017-01-01
A light metastable dark photon decaying into a collimated electron/positron pair can fake a photon, either converted or unconverted, at the LHC. The detailed object identification relies on the specifics of the detector and strategies for the reconstruction. We study the fake rate based on the ATLAS (CMS) detector geometry and show that it can be O(1) with a generic choice of parameters. Especially, the probability of being registered as a photon is angular dependent. Such detector effects can induce bias to measurements on certain properties of new physics. In this paper, we consider the scenario where dark photons in final states are from a heavy resonance decay. Consequently, the detector effects can dramatically affect the results when determining the spin of a resonance. Further, if the decay products from the heavy resonance are one photon and one dark photon, which has a large probability to fake a diphoton event, the resonance is allowed to be a vector. Because of the difference in detectors, the cross sections measured in ATLAS and CMS do not necessarily match. Furthermore, if the diphoton signal is given by the dark photons, the standard model Z γ and Z Z final states do not necessarily come with the γ γ channel, which is a unique signature in our scenario. The issue studied here is relevant also for any future new physics searches with photon(s) in the final state. We discuss possible ways of distinguishing dark photon decay and a real photon in the future.
18. Anomalous soft photon production from the induced currents in Dirac sea
Loshaj, Frasher; Kharzeev, Dmitri
2013-10-01
The propagation of a high energy quark distrurbs the confining vacuum inducing the currents in Dirac sea. Since quarks possess electric charge, these induced vacuum currents act as a source of soft photon radiation. This can lead to the enhancement of the soft photon production above the expectations based on the charged hadron yields and the Low theorem. We illustrate the phenomenon by using the exactly soluble 1 + 1 dimensional massless Abelian gauge model that shares with QCD all of the ingredients involved in this mechanism: confinement, chiral symmetry breaking, axial anomaly, and the periodic θ-vacuum. We show that the propagating quark throughout the process of hadronization induces in the vacuum charged transition currents that lead to a strong resonant enhancement of the soft photon yield; the Low theorem however remains accurate in the limit of very soft momenta. We then construct on the basis of our result a simple phenomenological model and apply it to the soft photon production in the fragmentation of jets produced in Z0 decays. We find a qualitative agreement with the recent result from the DELPHI Collaboration.
19. Anomalous soft photon production from the induced currents in Dirac sea
Kharzeev, Dmitri E.; Loshaj, Frashër
2014-04-01
The propagation of a high-energy quark disturbs the confining QCD vacuum inducing the currents in Dirac sea. Since quarks possess electric charge, these induced vacuum quark currents act as a source of soft photon radiation. This can lead to the enhancement of the soft photon production above the expectations based on the charged hadron yields and the Low theorem. We illustrate the phenomenon by using the exactly soluble 1+1 dimensional massless Abelian gauge model that shares with QCD all of the ingredients involved in this mechanism: confinement, chiral symmetry breaking, axial anomaly, and the periodic θ vacuum. We show that the propagating quark throughout the process of hadronization induces in the vacuum charged transition currents that lead to a strong resonant enhancement of the soft photon yield; the Low theorem, however, remains accurate in the limit of very soft momenta. We then construct on the basis of our result a simple phenomenological model and apply it to the soft photon production in the fragmentation of jets produced in Z0 decays. We find a qualitative agreement with the recent result from the DELPHI Collaboration.
20. o-nitrobenzyl photolabile protecting groups with red-shifted absorption: syntheses and uncaging cross-sections for one- and two-photon excitation.
PubMed
Aujard, Isabelle; Benbrahim, Chouaha; Gouget, Marine; Ruel, Odile; Baudin, Jean-Bernard; Neveu, Pierre; Jullien, Ludovic
2006-09-06
We evaluated the o-nitrobenzyl platform for designing photolabile protecting groups with red-shifted absorption that could be photolyzed upon one- and two-photon excitation. Several synthetic pathways to build different conjugated o-nitrobenzyl backbones, as well as to vary the benzylic position, are reported. Relative to the reference 4,5-dimethoxy-2-nitrobenzyl group, several o-nitrobenzyl derivatives exhibit a large and red-shifted one-photon absorption within the near-UV range. Uncaging after one-photon excitation was studied by measuring UV-visible absorption and steady-state fluorescence emission on model caged ethers and esters. In the whole series investigated, the caged substrates were released cleanly upon photolysis. Quantum yields of uncaging after one-photon absorption lie within the 0.1-1 % range. We observed that these drop as the maximum wavelength absorption of the o-nitrobenzyl protecting group is increased. A new method based on fluorescence correlation spectroscopy (FCS) after two-photon excitation was used to measure the action uncaging cross section for two-photon excitation. The series of o-nitrobenzyl caged fluorescent coumarins investigated exhibit values within the 0.1-0.01 Goeppert-Mayer (GM) range. Such results are in line with the low quantum yields of uncaging associated with cross-sections of 1-50 GM for two-photon absorption. Although the cross-sections for one- and two-photon absorption of o-nitrobenzyl photolabile protecting groups can be readily improved, we emphasize the difficulty in enlarging the corresponding action uncaging cross-sections in view of the observed trend of their quantum yield of uncaging.
1. Fast, accurate photon beam accelerator modeling using BEAMnrc: a systematic investigation of efficiency enhancing methods and cross-section data.
PubMed
Fragoso, Margarida; Kawrakow, Iwan; Faddegon, Bruce A; Solberg, Timothy D; Chetty, Indrin J
2009-12-01
In this work, an investigation of efficiency enhancing methods and cross-section data in the BEAMnrc Monte Carlo (MC) code system is presented. Additionally, BEAMnrc was compared with VMC++, another special-purpose MC code system that has recently been enhanced for the simulation of the entire treatment head. BEAMnrc and VMC++ were used to simulate a 6 MV photon beam from a Siemens Primus linear accelerator (linac) and phase space (PHSP) files were generated at 100 cm source-to-surface distance for the 10 x 10 and 40 x 40 cm2 field sizes. The BEAMnrc parameters/techniques under investigation were grouped by (i) photon and bremsstrahlung cross sections, (ii) approximate efficiency improving techniques (AEITs), (iii) variance reduction techniques (VRTs), and (iv) a VRT (bremsstrahlung photon splitting) in combination with an AEIT (charged particle range rejection). The BEAMnrc PHSP file obtained without the efficiency enhancing techniques under study or, when not possible, with their default values (e.g., EXACT algorithm for the boundary crossing algorithm) and with the default cross-section data (PEGS4 and Bethe-Heitler) was used as the "base line" for accuracy verification of the PHSP files generated from the different groups described previously. Subsequently, a selection of the PHSP files was used as input for DOSXYZnrc-based water phantom dose calculations, which were verified against measurements. The performance of the different VRTs and AEITs available in BEAMnrc and of VMC++ was specified by the relative efficiency, i.e., by the efficiency of the MC simulation relative to that of the BEAMnrc base-line calculation. The highest relative efficiencies were approximately 935 (approximately 111 min on a single 2.6 GHz processor) and approximately 200 (approximately 45 min on a single processor) for the 10 x 10 field size with 50 million histories and 40 x 40 cm2 field size with 100 million histories, respectively, using the VRT directional bremsstrahlung splitting
2. Application of Origen2.1 in the decay photon spectrum calculation of spallation products
Hong, Shuang; Yang, Yong-Wei; Xu, Hu-Shan; Meng, Hai-Yan; Zhang, Lu; Liu, Zhao-Qing; Gao, Yu-Cui; Chen, Kang
2016-11-01
Origen2.1 is a widely used computer code for calculating the burnup, decay, and processing of radioactive materials. However, the nuclide library of Origen2.1 is used for existing reactors like pressurized water reactors. To calculate the photon spectrum released by the decay of spallation products, we have made specific libraries for the ADS tungsten spallation target, based on the results given by the FLUKA Monte Carlo code. All the data used to make the Origen2.1 libraries are obtained from Nuclear structure & decay Data (NuDat2.6). The accumulated activity of spallation products and the contribution of nuclides to photon emission are given in this paper. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03030102)
3. Calculation of energy deposition, photon and neutron production in proton therapy of thyroid gland using MCNPX.
PubMed
Mowlavi, Ali Asghar; Fornasie, Maria Rosa; de Denaro, Mario
2011-01-01
In this study, the MCNPX code has been used to simulate a proton therapy in thyroid gland, in order to calculate the proton energy deposition in the target region. As well as, we have calculated the photon and neutron production spectra due to proton interactions with the tissue. We have considered all the layers of tissue, from the skin to the thyroid gland, and an incident high energy pencil proton beam. The results of the simulation show that the best proton energy interval, to cover completely the thyroid tissue, is from 42 to 54 MeV, assuming that the thyroid gland has a 14 mm thickness and is located 11.2mm under the skin surface. The most percentage of deposited energy (78%) is related to the 54 MeV proton energy beam. Total photon and neutron production are linear and polynomial second order functions of the proton energy, respectively.
4. Vacuum ultraviolet of hydrogenated amorphous carbons. II. Small hydrocarbons production in Photon Dominated Regions
Alata, I.; Jallat, A.; Gavilan, L.; Chabot, M.; Cruz-Diaz, G. A.; Munoz Caro, G. M.; Béroff, K.; Dartois, E.
2015-12-01
Context. Hydrogenated amorphous carbons (a-C:H) are a major component of the carbonaceous solids present in the interstellar medium. The production and existence of these grains is connected in particular with the balance between their photolysis, radiolysis, and hydrogenation. During grain processing, H2 and other small organic molecules, radicals, and fragments are released into the gas phase. Aims: We perform photolytic experiments on laboratory produced interstellar a-C:H analogues to monitor and quantify the release of species and compare to relevant observations in the interstellar medium. Methods: Hydrogenated amorphous carbon analogues at low temperature are exposed to ultraviolet (UV) photons, under ultra-high vacuum conditions. The species produced are monitored using mass spectrometry and post irradiation temperature-programmed desorption. Additional experiments are performed using deuterated analogues and the species produced are unambiguously separated from background contributions. We implement the laboratory measured yields for the released species in a time dependent model to investigate the effect of the UV photon irradiation of hydrogenated amorphous carbons in a photon dominated region, and estimate the associated time scale. Results: The UV photolysis of hydrogenated amorphous carbons leads to the production of H2 molecules and small hydrocarbons. The model shows that the photolytic evolution of a-C:Hs in photon dominated regions, such as the Horsehead Nebula, can raise the abundance of carbonaceous molecules by several orders of magnitude at intermediate visual extinctions, i.e., after the C+ maximum and before the dense cloud conditions prevail where models generally show a minimum abundance for such carbonaceous species. The injection time peak ranges from a thousand to ten thousand years in the models, considering only the destruction of such grains and no re-hydrogenation. This time scale is consistent with the estimated advection front of
5. Calculation of the cross section for top quark production
SciTech Connect
Berger, E.L.; Contopanagos, H.
1996-06-21
The authors summarize calculations of the cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength. In their approach they resume the universal leading-logarithm contributions, and they restrict the calculation to the region of phase space that is demonstrably perturbative. They compare the approach with other methods. They present predictions of the physical cross section as a function of the top quark mass in proton-antiproton reactions at center-of-mass energies of 1.8 and 2.0 TeV, and they discuss estimated uncertainties.
6. Positronium beam production and scattering cross-sections
Leslie, Dawn Elizabeth
In this work, the efficiency for the production of a monoenergetic positronium beam via the charge-exchange reaction of a positron beam in a gaseous target has been determined for molecular hydrogen and molecular nitrogen. In the case of molecular nitrogen, it has been found that the energy range over which a useful intensity of collimated positronium may be produced can be extended to 250eV, 100eV higher than previously achieved. This should enable measurements of the total and partial positronium cross-sections at correspondingly higher energies, where target inelastic effects are expected to be significant A recent measurement of the integrated positronium formation cross-section for xenon found a larger yield of positronium atoms compared to the other noble gases. A shoulder was also seen 10eV above the peak and it was suggested that this might be due to the production of positronium in an excited state. These findings have provided an incentive to investigate the collimated positronium production efficiency from xenon, which has been found to be surprisingly low. The quantum state of the beam atoms has also been found to be dominantly ground state. Possible reasons for these findings are discussed Total cross-sections for positronium-gas scattering have been extracted from the measurements of the positronium beam production efficiency for both molecular nitrogen and xenon. These quantities have also been determined directly by measuring the intensity of the positronium beam transmitted through a gas cell via the Beer-Lambert Law. A good consistency is found between the values obtained using this method and those determined indirectly. Recently, measurements have been made of the absolute integrated cross-section for the fragmentation of positronium in collision with helium atoms, along with the longitudinal energy distributions of the residual positrons in the energy range -Ep/=13-33eV. Measurements of the latter indicate a peak close to half the residual
7. Parton distributions with the combined HERA charm production cross sections
SciTech Connect
Bertone, Valerio; Rojo, Juan
2013-04-15
Heavy quark structure functions from HERA provide a direct handle on the medium and small-x gluon PDF. In this contribution, we discuss ongoing progress on the implementation of the FONLL General-Mass scheme with running heavy quark masses, and of its benchmarking with the HOPPET and OpenQCDrad codes, and then present the impact of the recently released combined HERA charm production cross sections in the NNPDF 2.3 analysis. We find that the combined charm data contribute to constraining the gluon and quarks at small values of Bjorken-x.
8. Influence of the four-photon parametric processes and cross-phase modulation on the relative motion of optical filaments
Kovachev, L. M.; Georgieva, D. A.; Dakova, A. M.
2015-10-01
We investigate two types of nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing {{P}\\text{cr}} . In the first case we study energy exchange between filaments. The model describes this process through a degenerate four-photon parametric mixing (FPPM) scheme and requests initial phase difference between the waves. When there is no initial phase difference between the pulses, the FPPM process does not work. In this case the second type of interaction is obtained as merging between two, three or four filaments in a single filament with higher power. It is found that in the second case the interflow between the filaments has the potential for interaction due to cross-phase modulation (CPM).
9. Code System for Producing Pointwise and Multigroup Neutron and Photon Cross Sections from ENDF/B Data.
SciTech Connect
MACFARLANE, ROBERT E.
1995-06-01
Version 04 The NJOY nuclear data processing system is a comprehensive computer code package for producing pointwise and multigroup neutron and photon cross sections from ENDF/B evaluated nuclear data. This is the last NJOY-91 series. It uses the same module structure as the earlier versions and its graphics options depend on DISSPLA. This new release, designated NJOY91.119, includes bug fixes, improvements in several modules, and some new capabilities. Information on the changes is included in the README file. A new test problem was added to test some ENDF-6 features, including Reich-Moore resonance reconstruction, energy-angle matrices in GROUPR, and energy-angle distributions in ACER. The 91.119 release is basically configured for UNIX.
10. Complete four-photon cluster-state analyzer based on cross-Kerr nonlinearity
Wang, Zhi-Hui; Zhu, Long; Su, Shi-Lei; Guo, Qi; Cheng, Liu-Yong; Zhu, Ai-Dong; Zhang, Shou
2013-09-01
We propose a method to construct an optical cluster-state analyzer based on cross-Kerr nonlinearity combined with linear optics elements. In the scheme, we employ two four-qubit parity gates and the controlled phase gate (CPG) from only the cross-Kerr nonlinearity and show that all the orthogonal four-qubit cluster states can be completely identified. The scheme is significant for the large-scale quantum communication and quantum information processing networks. In addition, the scheme is feasible and deterministic under current experimental conditions.
11. Production and elliptic flow of dileptons and photons in a matrix model of the quark-gluon plasma.
PubMed
Gale, Charles; Hidaka, Yoshimasa; Jeon, Sangyong; Lin, Shu; Paquet, Jean-François; Pisarski, Robert D; Satow, Daisuke; Skokov, Vladimir V; Vujanovic, Gojko
2015-02-20
We consider a nonperturbative approach to the thermal production of dileptons and photons at temperatures near the critical temperature in QCD. The suppression of colored excitations at low temperature is modeled by including a small value of the Polyakov loop, in a "semi"-quark-gluon plasma (QGP). Comparing the semi-QGP to the perturbative QGP, we find a mild enhancement of thermal dileptons. In contrast, to leading logarithmic order in weak coupling there are far fewer hard photons from the semi-QGP than the usual QGP. To illustrate the possible effects on photon and dilepton production in heavy-ion collisions, we integrate the rate with a simulation using ideal hydrodynamics. Dileptons uniformly exhibit a small flow, but the strong suppression of photons in the semi-QGP tends to weight the elliptical flow of photons to that generated in the hadronic phase.
12. CONSTRAINTS ON IONIZING PHOTON PRODUCTION FROM THE LARGE-SCALE Lyα FOREST
SciTech Connect
Pontzen, Andrew; Peiris, Hiranya; Bird, Simeon; Verde, Licia
2014-09-10
Recent work has shown that the z ≅ 2.5 Lyα forest on large scales encodes information about the galaxy and quasar populations that keep the intergalactic medium photoionized. We present the first forecasts for constraining the populations with data from current and next-generation surveys. At a minimum, the forest should tell us whether galaxies or, conversely, quasars dominate the photon production. The number density and clustering strength of the ionizing sources might be estimated to sub-10% precision with a DESI-like survey if degeneracies (e.g., with the photon mean-free-path, small-scale clustering power normalization, and potentially other astrophysical effects) can be broken by prior information. We demonstrate that when inhomogeneous ionization is correctly handled, constraints on dark energy do not degrade.
13. Slow light with large group index - bandwidth product in lattice-shifted photonic crystal waveguides
Tang, Jian; Li, Wenhui; Wu, Jun; Xu, Zhonghui
2016-10-01
This study presents a systematic optimization procedure to generate slow light with large group index, wideband, and low dispersion in an lattice-shifted photonic crystal waveguide. The waveguide is based on triangular lattice photonic crystal imposed by selectively altering the locations of the holes adjacent to the line defect. Under a constant group index criterion of ± 10% variation, when group indices are nearly constants of 24, 33, 46, 57, and 66, their corresponding bandwidths of flat band reach 24.2, 17.6, 12.8, 10.1 and 8.6 nm around 1550 nm, respectively. A nearly constant large group index - bandwidth product (GBP) of 0.37 is achieved for all cases. Low dispersion slow light propagation is confirmed by studying the relative temporal pulse-width spreading with the 2-D finite-difference time-domain method.
14. Measuring astrophysically relevant 36Cl production cross sections
Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Clark, Adam; Nelson, Austin; Beard, Mary; Collon, Philippe
2016-09-01
The short-lived radionuclide 36Cl (t1 / 2 = 0 . 301 Ma) is known to have existed in the Early Solar System (ESS), and evaluating its production sources can lead to better understanding of the processes taking place in ESS formation and their timescales. The X-wind model is used to explain 36Cl production via solar energetic particles from the young Sun, but is lacking empirical data for many relevant reactions. Bowers et al. (2013) measured the 33S(α,p)36Cl cross section at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by Hauser-Feshbach statistical model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. Recent results of the re-measurement of the 33S(α,p)36Cl reaction, providing greater coverage of the same energy range as Bowers et al., will be presented. Future plans for measurement of other 36Cl producing reactions will also be discussed.
15. Neutron Cross Section Covariances for Structural Materials and Fission Products
Hoblit, S.; Cho, Y.-S.; Herman, M.; Mattoon, C. M.; Mughabghab, S. F.; Obložinský, P.; Pigni, M. T.; Sonzogni, A. A.
2011-12-01
We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10 eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also 23Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.
16. Search for Production of Resonant States in the Photon-Jet Mass Distribution Using pp Collisions at s=7TeV Collected by the ATLAS Detector
2012-05-01
This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11fb-1 of proton-proton collisions at s=7TeV. We compare the photon+jet mass distribution to a background model derived from data and find consistency with the background-only hypothesis. Given the lack of evidence for a signal, we set 95% credibility level limits on generic Gaussian-shaped signals and on a benchmark excited-quark (q*) model, excluding 2 TeV Gaussian resonances with cross section times branching fraction times acceptance times efficiency near 5 fb and excluding q* masses below 2.46 TeV, respectively.
17. Neutron-skin effect in direct-photon and charged-hadron production in Pb+Pb collisions at the LHC
Helenius, Ilkka; Paukkunen, Hannu; Eskola, Kari J.
2017-03-01
A well-established observation in nuclear physics is that in neutron-rich spherical nuclei the distribution of neutrons extends farther than the distribution of protons. In this work, we scrutinize the influence of this so called neutron-skin effect on the centrality dependence of high-p_T direct-photon and charged-hadron production. We find that due to the estimated spatial dependence of the nuclear parton distribution functions, it will be demanding to unambiguously expose the neutron-skin effect with direct photons. However, when taking a ratio between the cross sections for negatively and positively charged high-p_T hadrons, even centrality-dependent nuclear-PDF effects cancel, making this observable a better handle on the neutron skin. Up to 10% effects can be expected for the most peripheral collisions in the measurable region.
18. Cross section asymmetry of two-body carbon disintegration 12C (γ , p)11B with polarized photons at energy 40-50 MeV
Burdeinyi, D.; Brudvik, J.; Fissum, K.; Ganenko, V.; Hansen, K.; Isaksson, L.; Livingston, K.; Lundin, M.; Nilsson, B.; Schroder, B.
2017-01-01
The cross section asymmetry of 12C (γ ,p01)11B and 12C (γ ,p2-6)11B reactions has been studied at the energy range 40-55 MeV, using linearly polarized tagged photons of the MAX-lab facility. The asymmetry of the 12C (γ ,p01)11B processes, which assume the one-body mechanism of the reaction, is Σ ≈ 0.82 ± 0.05 for photon energies 45-50 MeV. The asymmetry for the 12C (γ ,p2-6)11B reactions, which produce a maximum at excitation energy ∼ 6 MeV, is Σ ≈ 0.53 ± 0.13 for a photon energy 49 MeV. It is close to the asymmetry of reaction of the free deuteron photodisintegration, and can be resulted from the two-body mechanism of the photon absorption.
19. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution
SciTech Connect
Moreno, J.; Dobryakov, A. L.; Hecht, S. E-mail: [email protected]; Kovalenko, S. A. E-mail: [email protected]; Ioffe, I. N.; Granovsky, A. A.
2015-07-14
1-photon (382 nm) and 2-photon (752 nm) excitations to the S{sub 1} state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S{sub 1} → S{sub n} due to resonant absorption of a third pump photon. Subsequent S{sub n} → S{sub 1} internal conversion (with τ{sub 1} = 1 ps) prepares a very hot S{sub 1} state which cools down with τ{sub 2} = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ{sup (2)} = 32 ⋅ 10{sup −50} cm{sup 4} s at 752 nm are evaluated from the bleach signal.
20. Broadband transient absorption spectroscopy with 1- and 2-photon excitations: Relaxation paths and cross sections of a triphenylamine dye in solution.
PubMed
Moreno, J; Dobryakov, A L; Ioffe, I N; Granovsky, A A; Hecht, S; Kovalenko, S A
2015-07-14
1-photon (382 nm) and 2-photon (752 nm) excitations to the S1 state are applied to record and compare transient absorption spectra of a push-pull triphenylamine (TrP) dye in solution. After 1-photon excitation, ultrafast vibrational and structural molecular relaxations are detected on a 0.1 ps time scale in nonpolar hexane, while in polar acetonitrile, the spectral evolution is dominated by dipolar solvation. Upon 2-photon excitation, transient spectra in hexane reveal an unexpected growth of stimulated emission (SE) and excited-state absorption (ESA) bands. The behavior is explained by strong population transfer S1 → Sn due to resonant absorption of a third pump photon. Subsequent Sn → S1 internal conversion (with τ1 = 1 ps) prepares a very hot S1 state which cools down with τ2 = 13 ps. The pump pulse energy dependence proves the 2-photon origin of the bleach signal. At the same time, SE and ESA are strongly affected by higher-order pump absorptions that should be taken into account in nonlinear fluorescence applications. The 2-photon excitation cross sections σ(2) = 32 ⋅ 10(-50) cm(4) s at 752 nm are evaluated from the bleach signal.
1. Search for anomalous single top quark production in association with a photon in pp collisions at √(s) = 8 TeV
DOE PAGES
Khachatryan, Vardan
2016-04-06
We found the results of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for tγ events where t → Wb andW → μn is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum.more » Furthermore, there was no evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tug and tcg anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: B(t → uγ) < 1.3 x 10-4 and B(t →cγ) < 1.7 x 10-3. Upper limits are also set on the cross section of associated tγ production in a restricted phase-space region. These are the most stringent limits currently available.« less
2. Search for anomalous single top quark production in association with a photon in pp collisions at √(s) = 8 TeV
SciTech Connect
Khachatryan, Vardan
2016-04-06
We found the results of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for tγ events where t → Wb andW → μn is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum. Furthermore, there was no evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tug and tcg anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: B(t → uγ) < 1.3 x 10-4 and B(t →cγ) < 1.7 x 10-3. Upper limits are also set on the cross section of associated tγ production in a restricted phase-space region. These are the most stringent limits currently available.
3. Search for anomalous single top quark production in association with a photon in pp collisions at √{s}=8 TeV
2016-04-01
The result of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for tγ events where t → Wb and W → μν is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum. No evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tuγ and tcγ anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: ℬ(t → u γ) < 1.3 × 10- 4 and ℬ(t → c γ) < 1.7 × 10- 3. Upper limits are also set on the cross section of associated tγ production in a restricted phase-space region. These are the most stringent limits currently available. [Figure not available: see fulltext.
4. Production of Ac-225 for cancer therapy by photon-induced transmutation of Ra-226.
PubMed
Melville, G; Meriarty, H; Metcalfe, P; Knittel, T; Allen, B J
2007-09-01
The increasing application of Ac-225 for cancer therapy indicates the potential need for its increased production and availability. The production of Ac-225 has been achieved using bremsstrahlung photons from an 18 MV medical linear accelerator (linac) to bombard a Ra-226 target. A linac dose of 2800 Gy produced about 64 microCi of Ra-225, which decays to Ac-225. This result, while consistent with the theoretical calculations, is far too low to be of practical use. A more powerful linac is required that runs at a higher current, longer pulse length and higher frequency for practical production. This process could also lead to the reduction of the nuclear waste product Ra-226.
5. Measurement of the Zγ production cross section in pp collisions at 8 TeV and search for anomalous triple gauge boson couplings
SciTech Connect
Khachatryan, Vardan
2015-04-29
The cross section for the production of Zγ in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb-1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. Furthermore, the differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. These observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. As a result, limits on anomalous triple gauge couplings of ZZγ and Zγγ are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.
6. Measurement of the Zγ production cross section in pp collisions at 8 TeV and search for anomalous triple gauge boson couplings
DOE PAGES
Khachatryan, Vardan
2015-04-29
The cross section for the production of Zγ in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb-1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. Furthermore, the differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. These observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. As a result, limits on anomalous triple gaugemore » couplings of ZZγ and Zγγ are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.« less
7. Benchmarking two-photon absorption cross sections: performance of CC2 and CAM-B3LYP.
PubMed
Beerepoot, Maarten T P; Friese, Daniel H; List, Nanna H; Kongsted, Jacob; Ruud, Kenneth
2015-07-15
We investigate the performance of CC2 and TDDFT/CAM-B3LYP for the calculation of two-photon absorption (TPA) strengths and cross sections and contrast our results to a recent coupled cluster equation-of-motion (EOM-EE-CCSD) benchmark study [K. D. Nanda and A. I. Krylov, J. Chem. Phys., 2015, 142, 064118]. In particular, we investigate whether CC2 TPA strengths are significantly overestimated compared to higher-level coupled-cluster calculations for fluorescent protein chromophores. Our conclusion is that CC2 TPA strengths are only slightly overestimated compared to the reference EOM-EE-CCSD results and that previously published overestimated cross sections are a result of inconsistencies in the conversion of the TPA strengths to macroscopic units. TDDFT/CAM-B3LYP TPA strengths, on the other hand, are found to be 1.5 to 3 times smaller than the coupled-cluster reference for the molecular systems considered. The unsatisfactory performance of TDDFT/CAM-B3LYP can be linked to an underestimation of excited-state dipole moments predicted by TDDFT/CAM-B3LYP.
8. Inclusive pi^0, eta, and direct photon production at high transverse momentum in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV
SciTech Connect
STAR Collaboration; Abelev, Betty
2010-07-07
We report a measurement of high-p{sub T} inclusive {pi}{sup 0}, {eta}, and direct photon production in p + p and d + Au collisions at {radical}s{sub NN} = 200 GeV at midrapidity (0 < {eta} < 1). Photons from the decay {pi}{sup 0} {yields} {gamma}{gamma} were detected in the Barrel Electromagnetic Calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The {eta} {yields} {gamma}{gamma} decay was also observed and constituted the first {eta} measurement by STAR. The first direct photon cross section measurement by STAR is also presented, the signal was extracted statistically by subtracting the {pi}{sup 0}, {eta}, and {omega}(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading order perturbative QCD calculations.
9. Molecularly imprinted photonic polymers as sensing elements for the creation of cross-reactive sensor arrays.
PubMed
Xu, Dan; Zhu, Wei; Wang, Chen; Tian, Tian; Cui, Jiecheng; Li, Jian; Wang, Hui; Li, Guangtao
2014-12-08
By combining molecular imprinting and colloidal crystal templating, molecularly imprinted inverse-opal photonic polymers (MIPPs) acting as sensing elements have been exploited to create sensor arrays for the first time. With this new strategy, abundant sensing elements with differential sensing abilities were easily accessible. Because of the unique hierarchical porous structure integrated in each sensing element, high sensitivity and selectivity, fast response and self-reporting (label-free) detection could be simultaneously achieved. All these fascinating features indicate that MIPPs are ideal sensing elements for creating sensor arrays. By integrating the individual sensing elements on a substrate, the formed array chip delivers better portability and high-throughput capability. As a demonstration, six kinds of contaminants were selected as analytes. The detection and discrimination of these analytes and even their mixtures in a wide range of concentrations, particularly trace amounts of analyte against a high background of other components, could be achieved, indicating the powerful capability of MIPPs-based sensor array for sensing. These results suggest that the described strategy opens a new route for sensor array creation and should find important applications in a wide range of areas.
10. Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA
2013-02-01
Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections σ_red^{cbar{c}} for charm production are obtained in the kinematic range of photon virtuality 2.5≤ Q 2≤2000 GeV2 and Bjorken scaling variable 3ṡ10-5≤ x≤5ṡ10-2. The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W ± and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.
11. Search for anomalous production of events with a high energy lepton and photon at the Tevatron
SciTech Connect
2006-01-01
We present results of a search for the anomalous production of events containing a high-transverse momentum charged lepton (ℓ, either e or μ) and photon (γ), accompanied by missing transverse energy (ET), and/or additional leptons and photons, and jets (X). We use the same kinematic selection criteria as in a previous CDF search, but with a substantially larger data set, 305 pb-1, a p$\\bar{p}$ collision energy of 1.96 TeV, and the upgraded CDF II detector. We find 42 ℓγET events versus a standard model expectation of 37.3 ± 5.4 events. The level of excess observed in Run I, 16 events with an expectation of 7.6 ± 0.7 events (corresponding to a 2.7 σ effect), is not supported by the new data. In the signature of ℓℓγ + X we observe 31 events versus an expectation of 23.0 ± 2.7 events. In this sample we find no events with an extra photon or ET and so find no events like the one eeγγ ET event observed in Run I.
12. Production of f 2(1270) and f 0(975) mesons by photons and hadrons of energy 65 175 GeV
Apsimon, R. J.; Atkinson, M.; Baake, M.; Bagdasarian, L. S.; Barberis, D.; Brodbeck, T. J.; Brook, N.; Charity, T.; Clegg, A. B.; Coyle, P.; Danaher, S.; Danagulian, S.; Davenport, M.; Dickinson, B.; Diekmann, B.; Donnachie, A.; Doyle, A. T.; Eades, J.; Ellison, R. J.; Fiedler, F.; Flower, P. S.; Foster, J. M.; Galbraith, W.; Galumian, P. I.; Gapp, C.; Gebert, F.; Hallewell, G.; Heinloth, K.; Henderson, R. C. W.; Hickman, M. T.; Hoeger, K. C.; Hofmann, R. P.; Holzkamp, A.; Holzkamp, S.; Hughes-Jones, R. E.; Ibbotson, M.; Jacob, H. P.; Joseph, D.; Keemer, N. R.; Kingler, J.; Körsgen, G.; Kolya, S. D.; Lafferty, G. D.; McCann, H.; McClatchey, R.; McManus, C.; Mercer, D.; Morris, J. A. G.; Morris, J. V.; Newton, D.; O'Connor, A.; Oedingen, R.; Oganesian, A. G.; Ottewell, P. J.; Paterson, C. N.; Paul, E.; Reid, D.; Rotscheidt, H.; Sharp, P. H.; Söldner-Rembold, S.; Thacker, N. A.; Thompson, L.; Thompson, R. J.; Waterhouse, J.; Weigend, A. S.; Wilson, G. W.
1992-06-01
Measurements are reported of inclusive f 2(1270) and f 0(975) production in γp, π± p and K ± p collisions at photon beam energies of 65 to 175 GeV and hadron beam energies of 80 and 140 GeV. The f 2 and f 0 mesons were found at masses of 1.250 GeV and 0.961 GeV respectively. Inclusive f 2 production at low x F was found to have a similar p T dependence for each beam type, whereas an additional pion-exchange contribution was found for production by pions at high x F. Cross sections are compared with those for ρ0 production and give no indication of a non-qbar q component in either f-meson state.
13. Hadronic Production of Ψ(2S) Cross section and Polarization
SciTech Connect
Chung, Kwangzoo
2008-05-01
The hadronic production cross section and the polarization of Ψ(2S) meson are measured by using the data from p$\\bar{p}$ collisions at √s = 1.96 TeV collected by the Collider Detector at Fermilab. The datasets used correspond to integrated luminosity of 1.1 fb-1 and 800 pb-1, respectively. The decay Ψ(2S) → μ+μ- is used to reconstruct Ψ(2S) mesons in the rapidity range |y(Ψ(2S))| < 0.6. The coverage of the pT range is 2.0 GeV/c ≤ pT (Ψ(2S)) < 30 GeV/c for the cross section analysis and pT ≥ 5 GeV/c for the polarization analysis. For events with pT (Ψ(2S)) > 2 GeV/c the integrated inclusive cross section multiplied by the branching ratio for dimuon decay is 3.17 ± 0.04 ± 0.28 nb . This result agrees with the CDF Run I measurement considering the increased center-of-mass energy from 1.8 TeV to 1.96 TeV. The polarization of the promptly produced Ψ(2S) mesons is found to be increasingly longitudinal as pT increases from 5 GeV/c to 30 GeV/c. The result is compared to contemporary theory models.
14. On the analogy between pulse-pile-up in energy-sensitive, photon-counting detectors and level-crossing of shot noise
Roessl, Ewald; Bartels, Matthias; Daerr, Heiner; Proksa, Roland
2016-03-01
Shot noise processes are omnipresent in physics and many of their properties have been extensively studied in the past, including the particular problem of level crossing of shot noise. Energy-sensitive, photon-counting detectors using comparators to discriminate pulse-heights are currently heavily investigated for medical applications, e.g. for x-ray computed tomography and x-ray mammography. Surprisingly, no mention of the close relation between the two topics can be found in the literature on photon-counting detectors. In this paper, we point out the close analogy between level crossing of shot noise and the problem of determining count rates of photon- counting detectors subject to pulse pile-up. The latter is very relevant for obtaining precise forward models for photon-counting detectors operated under conditions of very high x-ray flux employed in clinical x-ray computed tomography. Although several attempts have been made to provide reasonably accurate, approximative models for the registered number of counts in x-ray detectors under conditions of high flux and arbitrary x-ray spectra, see, e.g., no exact, analytic solution is given in the literature for general continuous pulse shapes. In this paper we present such a solution for arbitrary response functions, x-ray spectra and continuous pulse shapes based on a result from the theory of level crossing. We briefly outline the theory of level crossing including the famous Rice theorem and translate from the language of level crossing to the language of photon-counting detection.
15. A Polarized High-Energy Photon Beam for Production of Exotic Mesons
SciTech Connect
Senderovich, Igor
2012-01-01
This work describes design, prototyping and testing of various components of the Jefferson Lab Hall D photon beamline. These include coherent bremsstrahlung radiators to be used in this facility for generating the photon beam, a fine resolution hodoscope for the facility's tagging spectrometer, and a photon beam position sensor for stabilizing the beam on a collimator. The principal instrumentation project was the hodoscope: its design, implementation and beam testing will be thoroughly described. Studies of the coherent bremsstrahlung radiators involved X-ray characterization of diamond crystals to identify the appropriate line of manufactured radiators and the proper techniques for thinning them to the desired specification of the beamline. The photon beam position sensor project involved completion of a designed detector and its beam test. The results of these shorter studies will also be presented. The second part of this work discusses a Monte Carlo study of a possible photo-production and decay channel in the GlueX experiment that will be housed in the Hall D facility. Specifically, the γ p → Xp → b1 π → ω π+1 π-1 channel was studied including its Amplitude Analysis. This exercise attempted to generate a possible physics signal, complete with internal angular momentum states, and be able to reconstruct the signal in the detector and find the proper set of JPC quantum numbers through an amplitude fit. Derivation of the proper set of amplitudes in the helicity basis is described, followed by a discussion of the implementation, generation of the data sets, reconstruction techniques, the amplitude fit and results of this study.
16. Dynamic control of photosynthetic photon flux for lettuce production in CELSS
NASA Technical Reports Server (NTRS)
Chun, C.; Mitchell, C. A.
1996-01-01
A new dynamic control of photosynthetic photon flux (PPF) was tested using lettuce canopies growing in the Minitron II plant-growth/canopy gas-exchange system. Canopy photosynthetic rates (Pn) were measured in real time and fedback for further environment control. Pn can be manipulated by changing PPF, which is a good environmental parameter for dynamic control of crop production in a Controlled Ecological Life-Support Systems CELSS. Decision making that combines empirical mathematical models with rule sets developed from recent experimental data was tested. With comparable yield indices and potential for energy savings, dynamic control strategies will contribute greatly to the sustainability of space-deployed CELSS.
17. Search for anomalous production of events with two photons and additional energetic objects at CDF
Aaltonen, T.; Adelman, J.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauer, G.; Beauchemin, P.-H.; Bedeschi, F.; Beecher, D.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.; Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.; Dagenhart, D.; Datta, M.; Davies, T.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca, C.; Demortier, L.; Deng, J.; Deninno, M.; D'Errico, M.; di Canto, A.; di Giovanni, G. P.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, T.; Dube, S.; Ebina, K.; Elagin, A.; Erbacher, R.; Errede, D.; Errede, S.; Ershaidat, N.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; Guimaraes da Costa, J.; Gunay-Unalan, Z.; Haber, C.; Hahn, S. R.; Halkiadakis, E.; Han, B.-Y.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hartz, M.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussein, M.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin, P. E.; Kato, Y.; Kephart, R.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leone, S.; Lewis, J. D.; Lin, C.-J.; Linacre, J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.; Loginov, A.; Lovas, L.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; MacQueen, D.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Mastrandrea, P.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione, A.; Mesropian, C.; Miao, T.; Mietlicki, D.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Nielsen, J.; Nodulman, L.; Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Osterberg, K.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramanov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penzo, A.; Phillips, T. I.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Potamianos, K.; Poukhov, O.; Prokoshin, F.; Pronko, A.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Renz, M.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ, J.; Rusu, V.; Rutherford, B.; Saarikko, H.; Safonov, A.; Sakumoto, W. K.; Santi, L.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon, Y.; Shreyber, I.; Simonenko, A.; Sinervo, P.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur, R.; Soha, A.; Somalwar, S.; Sorin, V.; Squillacioti, P.; Stanitzki, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Tipton, P.; Ttito-Guzmán, P.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Tourneur, S.; Trovato, M.; Tsai, S.-Y.; Tu, Y.; Turini, N.; Ukegawa, F.; Uozumi, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar, R.; Vogel, M.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Weinelt, J.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wolfe, H.; Wright, T.; Wu, X.; Würthwein, F.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.; Zhang, X.; Zheng, Y.; Zucchelli, S.; CDF Collaboration
2010-09-01
We present results of a search for anomalous production of two photons together with an electron, muon, τ lepton, missing transverse energy, or jets using pp¯ collision data from 1.1-2.0fb-1 of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs of new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.
18. Search for Anomalous Production of Events with Two Photons and Additional Energetic Objects at CDF
SciTech Connect
Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; /Waseda U. /Dubna, JINR
2009-10-01
The authors present results of a search for anomalous production of two photons together with an electron, muon, {tau} lepton, missing transverse energy, or jets using p{bar p} collision data from 1.1-2.0 fb{sup -1} of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs for new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.
19. ConnesFusionTensorProduct/Photon GluonFusion in Mitochondria
Wh-Maksoed, Prodi Of Physics Ui, Depok 16415-Indonesia; Ssi, Wh-Maksoed
2016-05-01
As in AJ Wassermann distinguished of classical invariant theory & quantum invariant theory subfactor, in S. Palcoux:From Neveu-Schwarz Subfactors & Connes Fusion'' described the subfactor theory & Witt-algebra whereas Andreas Thom's explanation about ConnesFusionTensorProduct/CFTP related Connes fusion to composition of homomorphism (i). classical tensor product O-X adds the changes,(ii). Relative tensor product H-X preserve the changes. For photonGluonFusion/PGF defined:''photon is the gauge boson of QED, the simplest of all boson'' devotes to CFT as quantum field theory which are invariant under conformal transformation & in 2D there are infinite dimensional algebra. Alain Connes states theirselves Connes fusion as associative tensor operation'' to be in coincidences with their dynamic behavior driven by the balance in mitochondrial fusion & fission (Carveney, 2007) from Peter Alexander Williams: Retinal neuronal remodeling in a model of Optic Atrophy'', Dec, 2011. Great acknowledged to the VicePresident of the R.I, HE.Mr. Drs. M. JUSUF KALLA.
20. Center of mass energy and system-size dependence of photon production at forward rapidity at RHIC
SciTech Connect
STAR Collaboration; Abelev, Betty
2010-07-05
We present the multiplicity and pseudorapidity distributions of photons produced in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 62.4 and 200 GeV. The photons are measured in the region -3.7 < {eta} < -2.3 using the photon multiplicity detector in the STAR experiment at RHIC. The number of photons produced per average number of participating nucleon pairs increases with the beam energy and is independent of the collision centrality. For collisions with similar average numbers of participating nucleons the photon multiplicities are observed to be similar for Au+Au and Cu+Cu collisions at a given beam energy. The ratios of the number of charged particles to photons in the measured pseudorapidity range are found to be 1.4 {+-} 0.1 and 1.2 {+-} 0.1 for {radical}s{sub NN} = 62.4 GeV and 200 GeV, respectively. The energy dependence of this ratio could reflect varying contributions from baryons to charged particles, while mesons are the dominant contributors to photon production in the given kinematic region. The photon pseudorapidity distributions normalized by average number of participating nucleon pairs, when plotted as a function of {eta} - ybeam, are found to follow a longitudinal scaling independent of centrality and colliding ion species at both beam energies.
1. Cross sections for the exclusive photon electroproduction on the proton and Generalized Parton Distributions
SciTech Connect
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sections $\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$ for the $ep\\to e^\\prime p^\\prime \\gamma$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.
2. Cross sections for the exclusive photon electroproduction on the proton and Generalized Parton Distributions
DOE PAGES
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sectionsmore » $$\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$$ for the $$ep\\to e^\\prime p^\\prime \\gamma$$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($$Q^2,x_B,t$$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.« less
3. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions.
PubMed
Jo, H S; Girod, F X; Avakian, H; Burkert, V D; Garçon, M; Guidal, M; Kubarovsky, V; Niccolai, S; Stoler, P; Adhikari, K P; Adikaram, D; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Compton, N; Contalbrigo, M; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dupre, R; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Harrison, N; Hattawy, M; Hicks, K; Hirlinger Saylor, N; Ho, D; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Joo, K; Joosten, S; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Kuhn, S E; Kuleshov, S V; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; McKinnon, B; Meziani, Z E; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Movsisyan, A; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Net, L A; Niculescu, G; Osipenko, M; Ostrovidov, A I; Paolone, M; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Puckett, A J R; Raue, B A; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Simonyan, A; Skorodumina, Iu; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S; Strakovsky, I I; Strauch, S; Sytnik, V; Tian, Ye; Tkachenko, S; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I
2015-11-20
Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}.
4. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions
Jo, H. S.; Girod, F. X.; Avakian, H.; Burkert, V. D.; Garçon, M.; Guidal, M.; Kubarovsky, V.; Niccolai, S.; Stoler, P.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Elouadrhiri, L.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Hattawy, M.; Hicks, K.; Hirlinger Saylor, N.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; McKinnon, B.; Meziani, Z. E.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Park, K.; Pasyuk, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Simonyan, A.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration
2015-11-01
Unpolarized and beam-polarized fourfold cross sections (d4σ /d Q2d xBd t d ϕ ) for the e p →e'p'γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q2,xB,t ) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H , expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction xB.
5. Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays
Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nemecek, S.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.; DELPHI Collaboration
2010-06-01
An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation process, with the neutral pairs being more effectively radiating than the charged ones.
6. Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at √{ s} = 8TeV
2016-08-01
Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy (ETmiss) were examined. The data sample was collected in pp collisions at √{ s} = 8TeV with the CMS detector at the LHC and corresponds to 7.4fb-1. The analysis focuses on scenarios in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The data were obtained using a specially designed trigger with dedicated low thresholds, providing good sensitivity to signatures with photons, ETmiss , and low hadronic energy. No excess of events over the standard model expectation is observed. The results are interpreted using the model of general gauge mediation. With the wino mass fixed at 10GeV above that of the bino, wino masses below 710GeV are excluded at 95% confidence level. Constraints are also set in the context of two simplified models, for which the analysis sets the lowest cross section limits on the electroweak production of supersymmetric particles.
7. Two-photon absorption cross section determination for fluorene derivatives: analysis of the methodology and elucidation of the origin of the absorption processes.
PubMed
Belfield, Kevin D; Bondar, Mykhailo V; Hernandez, Florencio E; Przhonska, Olga V; Yao, Sheng
2007-11-08
A comprehensive analysis of the well-known open aperture Z-scan method, using a modified equation for the change in transmittance, is presented and accounts for discrepancies in two-photon absorption (2PA) cross sections between picosecond and femtosecond excitation. This new approach takes into account excited-state absorption and stimulated emission of the molecules studied. The two-photon absorption cross-section spectra of a series of six fluorene-based derivatives, determined using picosecond pulses, over a broad spectral range (500-900 nm), and this approach using a modified fitting procedure in the open aperture Z-scan is reported. We demonstrate that the fluorene derivatives exhibit two-photon absorption cross-section values between 700 and 5000 GM, when excited into the two-photon allowed electronic state. Excitation anisotropy spectra, measured to investigate the nature of the observed linear and nonlinear absorption bands, are presented and provide insight into the 2PA process.
8. Effect of the concentration of organic dyes on their surface plasmon enhanced two-photon absorption cross section using activated Au nanoparticles
Cohanoschi, Ion; Yao, Sheng; Belfield, Kevin D.; Hernández, Florencio E.
2007-04-01
In this article we present the study of the surface plasmon enhanced two-photon absorption of a hydrophilic stilbene derivative (trans-4,4'-diaminostilbene) in aqueous solution at different concentrations. The observed exponential growth of the effective two-photon absorption cross section [σ2'(Au)] is attributed to the electric-field augmentation via surface plasmon resonance between nanoparticles, i.e., hot spots, and the molecular density on Au nanospheres. An unprecedented σ2'(Au)=550 000 GM has been measured. This result opens a new universe of applications in multiphoton imaging, photodynamic therapy, telecommunications, optical limiting, and multidimensional data storage using hybrid systems.
9. Cross strip microchannel plate imaging photon counters with high time resolution
SciTech Connect
Stonehill, Laura C; Shirey, Robert; Rabin, Michael W; Thompson, David C; Siegmund, Oswald H W; Vallerga, John V; Tremsin, Anton S
2010-01-01
We have implemented cross strip readout microchannel plate detectors in 18 mm active area format including open face (UV/particle) and sealed tube (optical) configurations. These have been tested with a field programmable gate array based parallel channel electronics for event encoding which can process high input event rates (> 5 MHz) with high spatial resolution. Using small pore MCPs (6 {micro}m) operated in a pair, we achieve gains of >5 x 10{sup 5} which is sufficient to provide spatial resolution of <35 {micro}m FHWM, with self triggered event timing accuracy of {approx}2 ns for sealed tube optical sensors. A peak quantum efficiency of {approx}19% at 500 nm has been achieved with SuperGenII photocathodes that have response over the 400 nm to 900 nm range. Local area counting rates of up to >200 events/mcp pore sec{sup -1} have been attained, along with image linearity and stability to better than 50 {micro}m.
10. Omega Omega and Proton-Antiproton Production in Two Photon Interactions at ARGUS
Tsipolitis, George
1990-01-01
The reactions gammagamma to 2pi^+2pi ^-2pi^0 and gamma gammatopi^+pi^-pi ^0pi^0 have been studied by using the ARGUS detector at the e^+e^ - storage ring DORIS II at DESY. In the 2pi^+2pi^ -2pi^0 final state the production of omega-mesons is observed and in particular the reaction gammagamma to omegaomega is seen for the first time. The cross section for gammagamma to omegaomega is found to have an enhancement at ~1.9GeV/c ^2 of about 12 nb. The topological cross sections for the reactions gammagamma to 2pi^+2 pi^-2pi^0 and gammagamma to omegapi^+pi^-pi ^0 are also measured. The production of charged rho -mesons is observed in the pi^+pi ^-pi^0pi^0 final state. The cross section for the reaction gamma gamma to rho ^+rho^- is measured for the first time. The cross section did not show a threshold enhancement similar to that found in the reaction gammagamma to rho^0rho^0 and is about a factor of four smaller. A spin parity analysis of the rho^+rho^- system shows that the cross section is dominated by the two amplitudes J^{P} = 0^+ and J^{P } = 2^+ with helicity 2.
11. Measurement of the Cross Section for Diphoton Production in barpp Collisions at √s=1.8 TeV
Takano, Takeshi; CDF Collaboration
1996-05-01
The cross section for prompt diphoton production in barpp collisions at √s=1.8 TeV is presented. The results are reported as a function of transverse energy of the photons, invariant mass of the two photons and transverse momentum of the two photon system. The data were collected by the Collider Detector at Fermilab during the 1993-95 Tevatron run which yielded approximately 80pb^-1 of accumulated luminosity. *We thank the Fermilab staffs and the technical staffs of the participating institutions for their vital contributions. This work was supported by the U.S. Department of Energy and National Science Foundation; the Italian Istituto Nazionale di Fisica Nucleare; the Ministry of Education, Science and Culture of Japan; the Natural Sciences and Engineering Research Council of Canada; the National Science Council of the Republic of China; and the A. P. Sloan Foundation. ^ Supported by the Ministry of Education, Science and Culture of Japan.
12. Photon induced Λ(1520) production and the role of the K* exchange
Toki, Hiroshi; García-Recio, Carmen; Nieves, Juan
2008-02-01
We study the photon induced Λ(1520) production in the effective Lagrangian method near threshold, EγLAB≤2GeV, and in the quark-gluon string model at higher energies 3GeV≤EγLAB≤5GeV. In particular, we study the role of the K* exchange for the production of Λ(1520) within the SU(6) Weinberg-Tomozowa chiral unitary model proposed by García-Recio, Nieves, and Salcedo [Phys. Rev. D 74, 034025 (2006)PRVDAQ0556-282110.1103/PhysRevD.74.034025]. The coupling of the Λ(1520) resonance to the NK¯* pair, which is dynamically generated, turns out to be relatively small and, thus, the K exchange mechanism dominates the reaction. In the higher energy region, where experimental data are available, the quark-gluon string mechanism with the K Regge trajectory reproduces both the energy and the angular distribution dependences of the Λ(1520) photoproduction reaction.
13. Reconsideration of the inclusive prompt photon production at the LHC with kT-factorization
Lipatov, A. V.; Malyshev, M. A.
2016-08-01
We reconsider the inclusive production of isolated prompt photons in p p collisions at the LHC energies in the framework of kT-factorization approach. Our analysis is based on the O (α αs) off-shell (depending on the transverse momenta of initial quarks and gluons) production amplitudes of q*g*→γ q and q*q¯*→γ g partonic subprocesses and transverse momentum dependent (or unintegrated) quark and gluon densities in a proton, which are chosen in accordance with the Kimber-Martin-Ryskin prescription. We show that the subleading high-order O (α αs2) contributions, not covered by the noncollinear evolution of parton densities, are important to describe latest LHC data.
14. Report on an improved calculation of the Beryllium-7 + proton -> Boron-8 + photon cross section at stellar energies
Zhang, X.; Nollett, Kenneth M.; Phillips, D. R.
2017-01-01
The radiative capture reaction, 7Be+p -> 8B+photon, is a subject of long-standing interest for nuclear astrophysics. Its cross section needs to be known at low energies (about 20 keV in our Sun), which unfortunately is too small to be directly measured in lab. Therefore, theories are used to extrapolate the higher-energy measurements down to the low energies. The previous studies, including microscopic and phenomenological models, face difficulties with estimating theoretical uncertainties. In this talk, I will present our studies based on the Halo-Effective-Field-Theory framework, which provides a systematic expansion for the reaction amplitude in terms of the low energy to the high energy scale ratio. Our next-to-leading-order formula can parameterize other existing results with sub-percent discrepancy in the relevant energy region, which is consistent with our theoretical uncertainty estimation based on the size of ignored higher order contributions. We then applied Bayesian analysis to constrain the theory parameters based on the direct capture data, and got a stringent constraint on the zero energy S factor, S(0)=21.3 +/- 0.7 (eV b). The error is less than half of the previously recommended value, S(0)=20.8 +/- 1.6 (eV b). The work is supported by the U.S. Department of Energy under Grant No. DE-FG02-93ER-40756 and No. DEFG02-97ER-41014.
15. Results on hadronic events from the MAC detector at PEP. I. Direct photon production. II. Precision R measurement and energy-energy correlations
SciTech Connect
Heltsley, B.K.
1984-07-01
Direct photon production in hadronic events from e/sup +/e/sup -/ ..-->.. hadrons has been studied at ..sqrt..s=29 GeV using the MAC detector at PEP. Both the charge asymmetry in the final state jets and total yield have been used to determine values of quark charges, which are in good agreement with the predictions of the fractionally charged quark-parton model. Limits have been established for anomalous sources of direct photons. Measurements of the total cross section and energy-energy correlations for e/sup +/e/sup -/ ..-->.. hadrons at ..sqrt..s=29 GeV with the MAC detector are presented. Two complementary event selections for the precision R measurement are described, one accepting events over nearly the entire 4..pi.. solid angle (minimizing extrapolation to unseen phase space), and the other restricted to wide angles (reducing two-photon backgrounds). The two methods agree, yield R = 3.93 +- 0.10 (which includes the effects of higher order radiative corrections), and given ..cap alpha../sub s/ = 0.19 +- 0.07, independent of fragmentation. The asymmetry in the energy-energy correlation cross section yields different results for ..cap alpha../sub s/ in different models, 0.185 in the string model and from 0.105 to 0.140 for incoherent jet formation, depending on the gluon fragmentation and momentum conservation algorithms. The string fragmentation model provides a satisfactory description of the measured correlation cross section, whereas incoherent jet fragmentation does not. 35 references.
16. Measurements of partial cross sections and photoelectron angular distributions for the photodetachment of Fe{sup -} and Cu{sup -} at visible photon wavelengths
SciTech Connect
Covington, A. M.; Duvvuri, Srividya S.; Emmons, E. D.; Kraus, R. G.; Williams, W. W.; Thompson, J. S.; Calabrese, D.; Carpenter, D. L.; Collier, R. D.; Kvale, T. J.; Davis, V. T.
2007-02-15
Photodetachment cross sections and the angular distributions of photoelectrons produced by the single-photon detachment of the transition metal negative ions Fe{sup -} and Cu{sup -} have been measured at four discrete photon wavelengths ranging from 457.9 to 647.1 nm (2.71-1.92 eV) using a crossed-beams laser photodetachment electron spectrometry (LPES) apparatus. Photodetachment cross sections were determined by comparing the photoelectron yields from the photodetachment of Fe{sup -} to those of Cu{sup -} and C{sup -}, which have known absolute photodetachment cross sections. Using the measured photodetachment cross sections, radiative electron attachment cross sections were calculated using the principle of detailed balance. Angular distributions were determined by measurements of laboratory frame, angle-, and energy-resolved photoelectrons as a function of the angle between the linear laser polarization vector and the momentum vector of the collected photoelectrons. Values of the asymmetry parameter have been determined by nonlinear least-squares fits to these angular distributions. The measured asymmetry parameters are compared to predictions of photodetachment models including Cooper and Zare's dipole approximation theory [J. Cooper and R. N. Zare, J. Chem. Phys. 48, 942 (1968)], and the angular momentum transfer theory developed by Fano and Dill [Phys. Rev. A 6, 185 (1972)].
17. Direct photon production in Pb–Pb collisions at sNN=2.76 TeV
DOE PAGES
2016-01-19
We studied the direct photon production at mid-rapidity in Pb-Pb collisions at √sNN = 2.76 TeV in the transverse momentum range 0.9 < pT < 14 GeV/c. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e- pair reconstructed in the central tracking system. Our results of the two methods were combined and direct photon spectra were measured for the 0-20%, 20-40%, and 40-80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT greater than or similar to 5 GeV/c. Direct photon spectramore » down to pT approximate to 1 GeV/c could be extracted for the 20-40% and 0-20% centrality classes. Furthermore, the significance of the direct photon signal for 0.9 < pT < 2.1 GeV/c is 2.6 sigma for the 0-20% class. The spectrum in this pT range and centrality class can be described by an exponential with an inverse slope parameter of (297 ± 12stat ± 41syst) MeV. State-of-the-art models for photon production in heavy-ion collisions agree with the data within uncertainties.« less
18. Direct photon production in Pb-Pb collisions at √{sNN} = 2.76 TeV
2016-03-01
Direct photon production at mid-rapidity in Pb-Pb collisions at √{sNN} = 2.76 TeV was studied in the transverse momentum range 0.9 Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the ALICE detector material with the e+e- pair reconstructed in the central tracking system. The results of the two methods were combined and direct photon spectra were measured for the 0-20%, 20-40%, and 40-80% centrality classes. For all three classes, agreement was found with perturbative QCD calculations for pT ≳ 5 GeV / c. Direct photon spectra down to pT ≈ 1 GeV / c could be extracted for the 20-40% and 0-20% centrality classes. The significance of the direct photon signal for 0.9 photon production in heavy-ion collisions agree with the data within uncertainties.
19. Biocompatible Green and Red Fluorescent Organic Dots with Remarkably Large Two-Photon Action Cross Sections for Targeted Cellular Imaging and Real-Time Intravital Blood Vascular Visualization.
PubMed
Xiang, Jiayun; Cai, Xiaolei; Lou, Xiaoding; Feng, Guangxue; Min, Xuehong; Luo, Wenwen; He, Bairong; Goh, Chi Ching; Ng, Lai Guan; Zhou, Jian; Zhao, Zujin; Liu, Bin; Tang, Ben Zhong
2015-07-15
Fluorescent organic dots are emerging as promising bioimaging reagents because of their high brightness, good photostability, excellent biocompatibility, and facile surface functionalization. Organic dots with large two-photon absorption (TPA) cross sections are highly desired for two-photon fluorescence microscopy. In this work, we report two biocompatible and photostable organic dots fabricated by encapsulating tetraphenylethene derivatives within DSPE-PEG matrix. The two organic dots show absorption maxima at 425 and 483 nm and emit green and red fluorescence at 560 and 645 nm, with high fluorescence quantum yields of 64% and 22%, respectively. Both organic dots exhibit excellent TPA property in the range of 800-960 nm, affording upon excitation at 820 nm remarkably large TPA cross sections of 1.2×10(6) and 2.5×10(6) GM on the basis of dot concentration. The bare fluorophores and their organic dots are biocompatible and have been used to stain living cells for one- and two-photon fluorescence bioimagings. The cRGD-modified organic dots can selectively target integrin αvβ3 overexpressing breast cancer cells for targeted imaging. The organic dots are also applied for real-time two-photon fluorescence in vivo visualization of the blood vasculature of mouse ear, providing the spatiotemporal information about the whole blood vascular network. These results demonstrate that the present fluorescent organic dots are promising candidates for living cell and tissue imaging.
20. Measurement of the Cross Section for Prompt Isolated Diphoton Production in $p\\bar{p}$ Collisions at \\sqrt s = 1.96 TeV
SciTech Connect
Vellidis, Costas; /Fermilab
2011-09-01
This article reports a measurement of the cross section of prompt isolated photon pair production in p{bar p} collisions at a total energy {radical}s = 1.96 TeV using data of 5.36 fb{sup -1} integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured cross section, differential in basic kinematic variables, is compared with three perturbative QCD predictions, a leading order (LO) parton shower calculation and two next-to-leading order (NLO) calculations. The NLO calculations reproduce most aspects of the data. By including photon radiation from quarks before and after hard scattering, the parton shower prediction becomes competitive with the NLO predictions.
1. Measurement of the cross section for prompt isolated diphoton production in pp collisions at square root(s) = 1.96 TeV.
PubMed
Aaltonen, T; Álvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bauer, G; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Brisuda, A; Bromberg, C; Brucken, E; Bucciantonio, M; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; De Cecco, S; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, D; Errede, S; Ershaidat, N; Eusebi, R; Fang, H C; Farrington, S; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Funakoshi, Y; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hidas, D; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirby, M; Klimenko, S; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Lin, C-J; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, Q; Liu, T; Lockwitz, S; Lockyer, N S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Martínez-Ballarín, R; Mastrandrea, P; Mathis, M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Potamianos, K; Poukhov, O; Pranko, A; Prokoshin, F; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rubbo, F; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Sakurai, Y; Santi, L; Sartori, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Sfyrla, A; Sgalaberna, D; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shiraishi, S; Shochet, M; Shreyber, I; Simonenko, A; Sinervo, P; Sissakian, A; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Somalwar, S; Sorin, V; Squillacioti, P; Stancari, M; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Ttito-Guzmán, P; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Tu, Y; Ukegawa, F; Uozumi, S; Varganov, A; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamaoka, J; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zucchelli, S
2011-09-02
This Letter reports a measurement of the cross section of prompt isolated photon pair production in pp collisions at a total energy square root(s)=1.96 TeV using data of 5.36 fb(-1) integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. The measured cross section, differential in basic kinematic variables, is compared with three perturbative QCD predictions, a leading order parton shower calculation and two next-to-leading order calculations. The next-to-leading order calculations reproduce most aspects of the data. By including photon radiation from quarks before and after hard scattering, the parton shower prediction becomes competitive with the next-to-leading order predictions.
2. Photon-induced Fission Product Yield Measurements on 235U, 238U, and 239Pu
Krishichayan, Fnu; Bhike, M.; Tonchev, A. P.; Tornow, W.
2015-10-01
During the past three years, a TUNL-LANL-LLNL collaboration has provided data on the fission product yields (FPYs) from quasi-monoenergetic neutron-induced fission of 235U, 238U, and 239Pu at TUNL in the 0.5 to 15 MeV energy range. Recently, we have extended these experiments to photo-fission. We measured the yields of fission fragments ranging from 85Kr to 147Nd from the photo-fission of 235U, 238U, and 239Pu using 13-MeV mono-energetic photon beams at the HIGS facility at TUNL. First of its kind, this measurement will provide a unique platform to explore the effect of the incoming probe on the FPYs, i.e., photons vs. neutrons. A dual-fission ionization chamber was used to determine the number of fissions in the targets and these samples (along with Au monitor foils) were gamma-ray counted in the low-background counting facility at TUNL. Details of the experimental set-up and results will be presented and compared to the FPYs obtained from neutron-induced fission at the same excitation energy of the compound nucleus. Work supported in part by the NNSA-SSAA Grant No. DE-NA0001838.
3. Evidence for WZ Production and a Measurement of the WZ Production Cross Section
SciTech Connect
Degenhardt, James D.
2007-05-01
This dissertation describes a test of the Standard Model (SM) of particle physics by measuring the probability, or cross section, of simultaneously producing a W boson and a Z boson from proton-antiproton collisions. The SM predicts the cross section of WZ production to be 3.68 ± 0.25 pb. The SM and physics of WZ production are described in Chapter 2 of this dissertation. The 1.96 TeV center-of-mass energy proton-antiproton collisions are provided by the Fermi National Accelerator Laboratory (FNAL) Tevatron Collider. The W and Z particles are detected using the D0 detector, which is described in Chapter 3. The data were collected by the detector during 2002-2006 corresponding to 1 fb-1 of p{bar p} collisions. This data set is described in Chapter 6. The measurement uses the trilepton (evee, μvee, evμμ, and μvμμ) decay channels, in which a W decays to a charged lepton plus a neutrino and a Z decays to a pair of charged leptons. The W and Z particle selection criteria, detection efficiency, and background determination are described in Chapter 7. We observe 13 candidate events in 1 fb-1 of p$\\bar{p}$ collisions. In this data set we expect to see 4.5 ± 0.6 background events, and we expect to see 9.2 ± 1.0 signal events. The probability of 4.5 ± 0.6 background events to fluctuate to 13 or more events is 1.2 x 10-3 which is a 3.0 σ deviation from the background estimate. A log likelihood method is used to determine the most likely cross section as determined by the measured signal efficiencies, the expected backgrounds, and the observed data. Presented in Chapter 8 is a measurement of the cross section for p$\\bar{p}$ → WZ + X at √s = 1.96 TeV. The WZ diboson production cross section is measured to be σWZ = 2.7$+1.7\\atop{-1.3}$ pb. This is in agreement with the predicted Standard Model cross section.
4. Photon initiated single top quark production via flavor-changing neutral currents at the LHC
Goldouzian, Reza; Clerbaux, Barbara
2017-03-01
Single top quark production is a powerful process to search for new physics signs. In this work we propose and investigate a search for top quark flavor-changing neutral currents (FCNCs) via a photon using direct single top quark production events in proton-proton collisions at the LHC at CERN. We show that the direct single top quark final state can provide constraints on the strengths of top-quark-γ and top-quark-gluon FCNC couplings simultaneously. Results of a search for direct single top quark production at the LHC at a center-of-mass energy of 8 TeV performed by the ATLAS Collaboration are used to set first experimental limits on the anomalous FCNC top decay branching fractions B (t →u γ )<0.05 % and B (t →c γ )<0.14 % via direct single top quark production. Finally, the sensitivity of the proposed channel for probing the top-quark-γ couplings at 13 TeV is presented.
5. Ionizing Photon Production and Escape in Extreme Starbursts: the Case of the Green Peas
2015-08-01
With similarities to high-redshift galaxies and potential Lyman continuum (LyC) escape, the low-redshift "Green Pea" (GP) galaxies represent an important test of ionizing photon production and feedback in young massive clusters. Using optical spectra and HST ACS emission-line imaging, we evaluate the ionizing sources, optical depths, and spatial variation of ionization in these unusual starbursts. The GPs’ spectra imply young starburst ages and possible low LyC optical depths. However, CLOUDY photoionization and Starburst99 models have difficulty reproducing all of the observed line ratios and suggest a need for additional hard ionizing sources. New ACS observations of four GPs highlight the extreme, compact nature of these bursts and reveal regions of low optical depth that are the likely sites of LyC escape.
6. Direct Photon Production at Next-to-Next-to-Leading Order
SciTech Connect
Campbell, John M.; Ellis, R. Keith; Williams, Ciaran
2016-12-13
We present the first calculation of direct photon production at next-to-next-to leading order (NNLO) accuracy in QCD. For this process, although the final state cuts mandate only the presence of a single electroweak boson, the underlying kinematics resembles that of a generic vector boson plus jet topology. In order to regulate the infrared singularities present at this order we use the $N$-jettiness slicing procedure, applied for the first time to a final state that at Born level includes colored partons but no required jet. We compare our predictions to ATLAS 8 TeV data and find that the inclusion of the NNLO terms in the perturbative expansion, supplemented by electroweak corrections, provides an excellent description of the data with greatly reduced theoretical uncertainties.
7. Evaluation of Cross-Section Sensitivities in Computing Burnup Credit Fission Product Concentrations
SciTech Connect
Gauld, I.C.
2005-08-12
U.S. Nuclear Regulatory Commission Interim Staff Guidance 8 (ISG-8) for burnup credit covers actinides only, a position based primarily on the lack of definitive critical experiments and adequate radiochemical assay data that can be used to quantify the uncertainty associated with fission product credit. The accuracy of fission product neutron cross sections is paramount to the accuracy of criticality analyses that credit fission products in two respects: (1) the microscopic cross sections determine the reactivity worth of the fission products in spent fuel and (2) the cross sections determine the reaction rates during irradiation and thus influence the accuracy of predicted final concentrations of the fission products in the spent fuel. This report evaluates and quantifies the importance of the fission product cross sections in predicting concentrations of fission products proposed for use in burnup credit. The study includes an assessment of the major fission products in burnup credit and their production precursors. Finally, the cross-section importances, or sensitivities, are combined with the importance of each major fission product to the system eigenvalue (k{sub eff}) to determine the net importance of cross sections to k{sub eff}. The importances established the following fission products, listed in descending order of priority, that are most likely to benefit burnup credit when their cross-section uncertainties are reduced: {sup 151}Sm, {sup 103}Rh, {sup 155}Eu, {sup 150}Sm, {sup 152}Sm, {sup 153}Eu, {sup 154}Eu, and {sup 143}Nd.
8. The effect of neutron skin on inclusive prompt photon production in Pb + Pb collisions at Large Hadron Collider energies
De, Somnath
2017-04-01
Recent experiments on lead ({{{Pb}}}82208) nuclei have observed the celebrated phenomenon of the neutron skin thickness of low energy nuclear physics. Skin thickness provides a measure of the extension of the spatial distribution of neutrons inside the atomic nucleus than protons. We have studied the effect of neutron skin thickness on inclusive prompt photon production in Pb + Pb collisions at Large Hadron Collider energies. We have calculated the ‘central-to-peripheral ratio’ ({R}{cp}) of prompt photon production with and without accounting for the neutron skin effect. The neutron skin causes a characteristic enhancement of the ratio, in particular at forward rapidity, which is distinguishable in our calculation. However, a very precise direct photon measurement up to large transverse momenta would be necessary to constrain the feature in experiment.
9. Inclusive direct photon production in the central and forward rapidity regions in proton - anti-proton collisions at a center-of-mass energy of 1800-GeV
SciTech Connect
Jerger, Steven A.
1997-01-01
A study of isolated direct photon production in proton-antiproton collisions at a center of mass energy √s= 1800 Ge V is reported, as measured at the D0 Fermilab Tevatron. Cross sections for the central (0 ≤ |η| ≤0.9) and forward (1.6 ≤ |η| ≤2.5) rapidity regions are presented as a function of photon (15 GeV≤ ET ≤ 150 GeV ), and compared with a next-to-leading order QCD calculation. In the central the data and theory are consistent in both shape and normalization; however, in the forward region the data are consistently above the theory, especially in the ET region below ~30 Ge V. A preliminary measurement of the correlation between the rapidity of the photon and that of the leading in the event shows qualitative agreement between the data and theoretical prediction.
10. Cross sections for H(-) and Cl(-) production from HCl by dissociative electron attachment
NASA Technical Reports Server (NTRS)
Orient, O. J.; Srivastava, S. K.
1985-01-01
A crossed target beam-electron beam collision geometry and a quadrupole mass spectrometer have been used to conduct dissociative electron attachment cross section measurements for the case of H(-) and Cl(-) production from HCl. The relative flow technique is used to determine the absolute values of cross sections. A tabulation is given of the attachment energies corresponding to various cross section maxima. Error sources contributing to total errors are also estimated.
11. Measurement of the Cross Section for Production of Prompt Diphoton in proton anti-proton Collisions at √s = 1.96-TeV
SciTech Connect
Liu, Yan-wen
2004-01-01
QCD production, and compared with next-to-leading order predictions. The background is subtracted using a statistical method based on the difference between the EM showers initiated by photons and by the backgrounds. The cross sections are measured as a function of diphoton mass, diphoton system transverse momentum and azimuthal angle between the two photons. The results are found to be consistent with perturbative QCD predictions.
12. Resonance formation in photon-photon collisions
SciTech Connect
Gidal, G.
1988-08-01
Recent experimental progress on resonance formation in photon-photon collisions is reviewed with particular emphasis on the pseudoscalar and tensor nonents and on the ..gamma gamma..* production of spin-one resonances. 37 refs., 17 figs., 5 tabs.
13. SU-E-T-112: An OpenCL-Based Cross-Platform Monte Carlo Dose Engine (oclMC) for Coupled Photon-Electron Transport
SciTech Connect
Tian, Z; Shi, F; Folkerts, M; Qin, N; Jiang, S; Jia, X
2015-06-15
Purpose: Low computational efficiency of Monte Carlo (MC) dose calculation impedes its clinical applications. Although a number of MC dose packages have been developed over the past few years, enabling fast MC dose calculations, most of these packages were developed under NVidia’s CUDA environment. This limited their code portability to other platforms, hindering the introduction of GPU-based MC dose engines to clinical practice. To solve this problem, we developed a cross-platform fast MC dose engine named oclMC under OpenCL environment for external photon and electron radiotherapy. Methods: Coupled photon-electron simulation was implemented with standard analogue simulation scheme for photon transport and Class II condensed history scheme for electron transport. We tested the accuracy and efficiency of oclMC by comparing the doses calculated using oclMC and gDPM, a previously developed GPU-based MC code on NVidia GPU platform, for a 15MeV electron beam and a 6MV photon beam in a homogenous water phantom, a water-bone-lung-water slab phantom and a half-slab phantom. We also tested code portability of oclMC on different devices, including an NVidia GPU, two AMD GPUs and an Intel CPU. Results: Satisfactory agreements were observed in all photon and electron cases, with ∼0.48%–0.53% average dose differences at regions within 10% isodose line for electron beam cases and ∼0.15%–0.17% for photon beam cases. It took oclMC 3–4 sec to perform transport simulation for electron beam on NVidia Titan GPU and 35–51 sec for photon beam, both with ∼0.5% statistical uncertainty. The computation was 6%–17% slower than gDPM due to the differences in both physics model and development environment, which is considered not significant for clinical applications. In terms of code portability, gDPM only runs on NVidia GPUs, while oclMC successfully runs on all the tested devices. Conclusion: oclMC is an accurate and fast MC dose engine. Its high cross
14. Two-Photon Ratiometric Fluorescence Probe with Enhanced Absorption Cross Section for Imaging and Biosensing of Zinc Ions in Hippocampal Tissue and Zebrafish.
PubMed
Li, Wanying; Fang, Bingqing; Jin, Ming; Tian, Yang
2017-02-21
Zinc ion (Zn(2+)) not only plays an important function in the structural, catalytic, transcription, and regulatory of proteins, but is also an essential ionic signal to regulate brain neurotransmitters pass process. In this work, we designed and synthesized an intramolecular charge transfer-based ratiometric two-photon fluorescence probe, P-Zn, for imaging and biosensing of Zn(2+) in live cell, hippocampal tissue, and zebrafish. The developed probe demonstrated high two-photon absorption cross section (δ) of 516 ± 77 GM, which increased to 958 ± 144 GM after the probe was coordinated with Zn(2+). Furthermore, this P-Zn probe quickly recognized Zn(2+) with high selectivity, over other metal ions, amino acids, and reactive oxygen species. More interestingly, the initial emission peak of the present probe at 465 nm decreased with a new peak increased at 550 nm, leading to the ratiometric determination of Zn(2+) with high accuracy. Finally, this two-photon fluorescence probe with high temporal resolution and remarkable analytical performance, as well as low-cytotoxicity, was successfully applied in imaging of live cells, hippocampal tissues, and zebrafishes. The present P-Zn probe combined with FLIM provided accurate mapping of Zn(2+) distribution at single-cell level. More interestingly, the two-photon spectroscopic results demonstrated that the level of Zn(2+) in hippocampal tissue of mouse with AD was higher than that in normal mouse brain.
15. a Measurement of the Total Photon-Proton Cross Section in the Center of Mass Energy Range 167 TO 194 GEV
Burow, Burkhard Dietrich
The thesis is a complete presentation of a total photon-proton (gamma p) cross section measurement using the ZEUS detector at the recently commissioned HERA electron-proton (ep) collider. A measurement of gamma p interactions using the exchanged virtual photon of ep collisions is shown to be justified and the correct flux of photons is determined. HERA and ZEUS are introduced, with an emphasis on the components used in the measurement. The data was collected during the fall of 1992 for which the experimental conditions are described, including the determination of the 13 nb ^{-1} of integrated ep luminosity which provided the event sample. The treatment of background events is described, as are event losses due to inefficiencies in their identification by the trigger and in their subsequent analysis. The observed number of events is corrected for the acceptance of the experiment using Monte Carlo simulations of gamma p interactions tuned to match characteristics of the observed events. Radiative corrections to the measurement are shown to be small and the calculation is corroborated by a measurement of the number of radiative events. In the gamma p center of mass energy range 167 < W < 194 GeV, the total gamma p cross section is sigma _sp{rm tot}{gamma p} = 143 +/- 3 (stat.) +/- 18 (syst.) mub.
16. Vacuum ultraviolet photon-mediated production of [(18) F]F2.
PubMed
Krzyczmonik, Anna; Keller, Thomas; Kirjavainen, Anna K; Forsback, Sarita; Solin, Olof
2017-04-01
The chemistry of F2 and its derivatives are amenable to facile aliphatic or aromatic substitution, as well as electrophilic addition. The main limitation in the use of [(18) F]F2 for radiopharmaceutical synthesis is the low specific activity achieved by the traditional methods of production. The highest specific activities, 55 GBq/μmol, for [(18) F]F2 have been achieved so far by using electrical discharge in the post-target production of [(18) F]F2 gas from [(18) F]CH3 F. We demonstrate that [(18) F]F2 is produced by illuminating a gas mixture of neon/F2 /[(18) F]CH3 F with vacuum ultraviolet photons generated by an excimer laser. We tested several illumination chambers and production conditions. The effects of the initial amount of [(18) F]F(-) , amount of carrier F2 , and number of 193-nm laser pulses at constant power were evaluated regarding radiochemical yield and specific activity. The specific activity attained for [(18) F]F2 -derived [(18) F]NFSi was 10.3 ± 0.9 GBq/μmol, and the average radiochemical yield over a wide range of conditions was 6.7% from [(18) F]F(-) . The production can be improved by optimization of the synthesis device and procedures. The use of a commercially available excimer laser and the simplicity of the process can make this method relatively easy for adaptation in radiochemistry laboratories.
17. Intermodal and cross-polarization four-wave mixing in large-core hybrid photonic crystal fibers.
PubMed
Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper
2015-03-09
Degenerate four-wave mixing is considered in large mode area hybrid photonic crystal fibers, combining photonic bandgap guidance and index guidance. Co- and orthogonally polarized pump, signal and idler fields are considered numerically by calculating the parametric gain and experimentally by spontaneous degenerate four-wave mixing. Intermodal and birefringence assisted intramodal phase matching is observed. Good agreement between calculations and experimental observations is obtained. Intermodal four-wave mixing is achieved experimentally with a conversion efficiency of 17%.
18. Making baryons dark: the quantum prediction of the variation of photon-particle scattering cross section with the approach to equilibrium in deep gravity wells
Ernest, Alllan David; Collins, Matthew P.
2015-08-01
Analysis of astrophysical phenomena relies on knowledge of cross sections. These cross sections are measured in scattering experiments, or calculated using theoretical techniques such as partial wave analysis. It has been recently shown [1,2,3] however that photon scattering cross sections depend also on the degree of localization of the target particle, and that particles in large-scale, deep-gravity wells can exhibit lower cross sections than those measured in lab-based experiments where particles are implicitly localized. This purely quantum effect arises as a consequence of differences in the gravitational eigenspectral distribution of a particle’s wavefunction in different situations, and is in addition to the obvious notion that delocalized particle scattering is less likely simply because the target particles are ‘in a bigger box’.In this presentation we consider the quantum equilibrium statistics of particles in gravitational potentials corresponding to dark matter density profiles. We show that as galactic halos approach equilibrium, the dark eigenstates of the eigenspectral ensemble are favoured and baryons exhibit lower photon scattering cross sections, rendering halos less visible than expected from currently accepted cross sections. Traditional quantum theory thus predicts that baryons that have not coalesced into self-bound macroscopic structures such as stars, can essentially behave as dark matter simply by equilibrating within a deep gravity well. We will discuss this effect and the consequences for microwave anisotropy analysis and primordial nucleosynthesis.[1] Ernest, A. D., and Collins, M. P., 2014, Australian Institute of Physics, AIP Congress, Canberra, December, 2014.[2] Ernest, A. D., 2009, J. Phys. A: Math. Theor., 42, 115207, 115208.[3] Ernest, A. D., 2012, In Prof. Ion Cotaescu (Ed) Advances in Quantum Theory (pp 221-248). Rijeka: InTech. ISBN 978-953-51-0087-4
19. Next-to-leading order QCD predictions for the signal of dark matter and photon associated production at the LHC
SciTech Connect
Wang Jian; Shao Dingyu; Zhang Hao; Li Chongsheng
2011-10-01
We study the potential of the LHC to discover the signal of dark matter associated production with a photon induced by a dimension six effective operator, including next-to-leading order QCD corrections. We investigate the main backgrounds from the standard model, i.e. Z boson and a photon associated production with invisible decay of Z boson, and Z boson and a jet production with the jet misidentified as a photon. We find that the p{sub T}{sup {gamma}} distributions of the backgrounds decrease faster than that of the signal with increasing of the transverse momentum of the photon. The {eta}{sup {gamma}} distributions of the backgrounds are almost flat in the full range of {eta}{sup {gamma}}. In contrast, the signal lies mainly in the central region of {eta}{sup {gamma}}. These characteristics may help to select the events in experiments. We show that in the parameter space allowed by the relic abundance constraint, which we have calculated at the next-to-leading-order QCD level, the LHC with {radical}(S)=7 TeV may discover this signal at the 5{sigma} level after collecting an integrated luminosity of 1 fb{sup -1}. On the other hand, if this signal is not observed at the LHC, we can set a lower limit on the new physics scale at the 3{sigma} level.
20. Soft X-Ray Irradiation of Methanol Ice: Formation of Products as a Function of Photon Energy
Chen, Y.-J.; Ciaravella, A.; Muñoz Caro, G. M.; Cecchi-Pestellini, C.; Jiménez-Escobar, A.; Juang, K.-J.; Yih, T.-S.
2013-12-01
Pure methanol ices have been irradiated with monochromatic soft X-rays of 300 and 550 eV close to the 1s resonance edges of C and O, respectively, and with a broadband spectrum (250-1200 eV). The infrared (IR) spectra of the irradiated ices show several new products of astrophysical interest such as CH2OH, H2CO, CH4, HCOOH, HCOCH2OH, CH3COOH, CH3OCH3, HCOOCH3, and (CH2OH)2, as well as HCO, CO, and CO2. The effect of X-rays is the result of the combined interactions of photons and electrons with the ice. A significant contribution to the formation and growth of new species in the CH3OH ice irradiated with X-rays is given by secondary electrons, whose energy distribution depends on the energy of X-ray photons. Within a single experiment, the abundances of the new products increase with the absorbed energy. Monochromatic experiments show that product abundances also increase with the photon energy. However, the abundances per unit energy of newly formed species show a marked decrease in the broadband experiment as compared to irradiations with monochromatic photons, suggesting a possible regulatory role of the energy deposition rate. The number of new molecules produced per absorbed eV in the X-ray experiments has been compared to those obtained with electron and ultraviolet (UV) irradiation experiments.
1. Measurement of the photon electroproduction cross section at JLAB with the goal of performing a Rosenbluth separation of the DVCS contribution
SciTech Connect
Jimenez-Arguello, Alejandro Marti
2014-07-11
The study of the inner structure of hadrons allows us to understand the nature of the interactions between partons, quarks and gluons, described by Quantum Chromodynamics. The elastic scattering reactions, which have been studied in order to measure the nucleon form factors, are included in this frame. The inelastic scattering reactions are also included in this frame, they allow us to obtain information about the nucleon structure thanks to the development of the parton distribution functions (PDFs). While through elastic scattering we can obtain information about the charge distribution of the nucleon, and hence, about the spatial distribution of the partons, through inelastic scattering we obtain information about the momentum distributions of partons, by employing the PDFs. However, we can study the exclusive inelastic scattering reactions, such as the Deeply Virtual Compton Scattering (DVCS), wich allow us to access to the spatial and momentum distributions simultaneously. This is possible thanks to the generalized parton distributions (GPDs), which allow us to correlate both types of distributions. The process known as DVCS is the easiest way to access the GPDs. This process can be expressed as the scattering of an electron by a proton by means of a virtual photon with the result of the scattered initial particles plus a real photon. We find a process competing with DVCS known as Bethe-Heitler (BH), in which the real photon is radiated by the lepton rather than the quark. Due to the small cross section of DVCS, of the order of nb, in order to conduct these kind of experiments it is necessary to make use of facilities capable of providing high beam intensities. One of these facilities is the Thomas Jefferson National Accelerator Facility , where the experiment JLab E07-007, "Complete Separation of Virtual Photon and π⁰ Electroproduction Observables of Unpolarized Protons", took place during the months of October to December of 2010. The main goal of this
2. Discrete quantum Fourier transform using weak cross-Kerr nonlinearity and displacement operator and photon-number-resolving measurement under the decoherence effect
Heo, Jino; Kang, Min-Sung; Hong, Chang-Ho; Yang, Hyeon; Choi, Seong-Gon
2016-12-01
We present a scheme for implementing discrete quantum Fourier transform (DQFT) with robustness against the decoherence effect using weak cross-Kerr nonlinearities (XKNLs). The multi-photon DQFT scheme can be achieved by operating the controlled path and merging path gates that are formed with weak XKNLs and linear optical devices. To enhance feasibility under the decoherence effect, in practice, we utilize a displacement operator and photon-number-resolving measurement in the optical gate using XKNLs. Consequently, when there is a strong amplitude of the coherent state, we demonstrate that it is possible to experimentally implement the DQFT scheme, utilizing current technology, with a certain probability of success under the decoherence effect.
3. Systematics of isotopic production cross sections from interactions of relativistic 40Ca in hydrogen
Chen, C.-X.; Albergo, S.; Caccia, Z.; Costa, S.; Crawford, H. J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T. G.; Insolia, A.; Knott, C. N.; Lindstrom, P. J.; McMahon, M.; Mitchell, J. W.; Potenza, R.; Russo, G. V.; Soutoul, A.; Testard, O.; Tull, C. E.; Tuvé, C.; Waddington, C. J.; Webber, W. R.; Wefel, J. P.
1997-09-01
The isotopic production cross sections for 40Ca projectiles at 357, 565, and 763 MeV/nucleon interacting in a liquid hydrogen target have been measured by the Transport Collaboration at the LBL HISS facility. The systematics of these cross sections are studied, and the results indicate that nuclear structure effects are present in the isotope production process during the relativistic collisions. The newly measured cross sections are also compared with those predicted by semiempirical and parametric formulas, but the predictions do not fully describe the systematics such as the energy dependence. The consequences of the cross section systematics in galactic cosmic ray studies are also discussed.
4. Electro-magnetic physics studies at RHIC: Neutral pion production, direct photon HBT, photon elliptic flow in gold-gold collisions at sqrt(s_NN) = 200 GeV and the Muon Telescope Detector simulation
Lin, Guoji
Electro-magnetic (E&M) probes such as direct photons and muons (mu) are important tools to study the properties of the extremely hot and dense matter created in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC). In this thesis, several topics of E&M physics will be addressed, including neutral pion (pi0) production, direct photon HBT, and photon elliptic flow (v2) in Au+Au collisions at sNN = 200 GeV. A discussion on the simulation study of the new Muon Telescope Detector (MTD) will also be presented. The pi0 production is a fundamental measurement of hadron production and prerequisite for the background study of direct photons. Neutral pions are reconstructed using the photons detected by the STAR Barrel Electro-magnetic Calorimeter (BEMC) and the Time Projection Chamber (TPC). Spectra of pi 0 are measured at transverse momentum 1 < pT < 12 GeV/c near mid-rapidity (0 < eta < 0.8) in 200 GeV Au+Au collisions. The spectra and nuclear modification factors RCP and RAA are compared to earlier pi+/- and pi0 results. Direct photon Hanbury-Brown and Twiss (HBT) correlations can reveal information of the system size throughout the whole collision. A first attempt of direct photon HBT study at RHIC in 200 GeV Au+Au collisions is done using photons detected by the STAR BEMC and TPC. All unknown correlation at small Qinv is observed, whose magnitude is much larger than the expected HBT signal, and possible causes of the correlation will be discussed. Direct photon elliptic flow (v2) at intermediate to high pT is sensitive to the source of direct photon production. Results of inclusive photon v2 in 200 GeV Au+Au collisions are presented. The v2 of pi0 decay photons is calculated from the previously published pi results. The comparison between inclusive and decay photon v 2 indicates that direct photon v2 is small. A new large-area Muon Telescope Detector at mid-rapidity at RHIC is proposed and under investigation, using the Long-strip Multi-Gap Resistive Plate
5. Ten years of photonics education at the college level in Ontario: results and by-products
Nantel, Marc
2010-08-01
In 2000, there was no way for an Ontario student to obtain a credential in optics, laser or photonics without going through graduate school. This was in, arguably, the world-leading jurisdiction in photonics-enabled telecommunications industry. To alleviate this problem and supply the job market with highly-qualified people in the field of optics and photonics, the Ontario Centres of Excellence - then as Photonics Research Ontario - partnered with Algonquin College (Ottawa) and Niagara College (Welland) to establish over the past decade a suite of programs: a 1-year Certificate in Advanced Lasers, a 2-year Diploma for Photonics Engineering Technician, a 3-year Diploma for Photonics Engineering Technologists and a 4-year Bachelor of Applied Technology - Photonics. Much has been learnt along the way - the crucial need for industrial partner and government support, for example - and many course corrections had to be made (telecom bust, anyone?). The author will share the results of this 10-year journey so far, the lessons learnt, and a view to the next ten years for these programs and photonics education in Ontario in general.
6. Effect of polarization entanglement in photon-photon scattering
Rätzel, Dennis; Wilkens, Martin; Menzel, Ralf
2017-01-01
It is found that the differential cross section of photon-photon scattering is a function of the degree of polarization entanglement of the two-photon state. A reduced general expression for the differential cross section of photon-photon scattering is derived by applying simple symmetry arguments. An explicit expression is obtained for the example of photon-photon scattering due to virtual electron-positron pairs in quantum electrodynamics. It is shown how the effect in this explicit example can be explained as an effect of quantum interference and that it fits with the idea of distance-dependent forces.
7. Two-photon polymerization for production of human iPSC-derived retinal cell grafts.
PubMed
Worthington, Kristan S; Wiley, Luke A; Kaalberg, Emily E; Collins, Malia M; Mullins, Robert F; Stone, Edwin M; Tucker, Budd A
2017-03-25
Recent advances in induced pluripotent stem cell (iPSC) technology have paved the way for the production of patient-specific neurons that are ideal for autologous cell replacement for treatment of neurodegenerative diseases. In the case of retinal degeneration and associated photoreceptor cell therapy, polymer scaffolds are critical for cellular survival and integration; however, prior attempts to materialize this concept have been unsuccessful in part due to the materials' inability to guide cell alignment. In this work, we used two-photon polymerization to create 180 μm wide non-degradable prototype photoreceptor scaffolds with varying pore sizes, slicing distances, hatching distances and hatching types. Hatching distance and hatching type were significant factors for the error of vertical pore diameter, while slicing distance and hatching type most affected the integrity and geometry of horizontal pores. We optimized printing parameters in terms of structural integrity and printing time in order to create 1 mm wide scaffolds for cell loading studies. We fabricated these larger structures directly on a porous membrane with 3 µm diameter pores and seeded them with human iPSC-derived retinal progenitor cells. After two days in culture, cells nested in and extended neuronal processes parallel to the vertical pores of the scaffolds, with maximum cell loading occurring in 25 μm diameter pores. These results highlight the feasibility of using this technique as part of an autologous stem cell strategy for restoring vision to patients affected with retinal degenerative diseases.
8. Indirect dark matter signatures in the cosmic dark ages. II. Ionization, heating, and photon production from arbitrary energy injections
Slatyer, Tracy R.
2016-01-01
Any injection of electromagnetically interacting particles during the cosmic dark ages will lead to increased ionization, heating, production of Lyman-α photons and distortions to the energy spectrum of the cosmic microwave background, with potentially observable consequences. In this paper we describe numerical results for the low-energy electrons and photons produced by the cooling of particles injected at energies from keV to multi-TeV scales, at arbitrary injection redshifts (but focusing on the post-recombination epoch). We use these data, combined with existing calculations modeling the cooling of these low-energy particles, to estimate the resulting contributions to ionization, excitation and heating of the gas, and production of low-energy photons below the threshold for excitation and ionization. We compute corrected deposition-efficiency curves for annihilating dark matter, and demonstrate how to compute equivalent curves for arbitrary energy-injection histories. These calculations provide the necessary inputs for the limits on dark matter annihilation presented in the accompanying paper I, but also have potential applications in the context of dark matter decay or deexcitation, decay of other metastable species, or similar energy injections from new physics. We make our full results publicly available at http://nebel.rc.fas.harvard.edu/epsilon, to facilitate further independent studies. In particular, we provide the full low-energy electron and photon spectra, to allow matching onto more detailed codes that describe the cooling of such particles at low energies.
9. Calculations of photo-induced X-ray production cross-sections in the energy range 1-150 keV and average fluorescence yields for Zn, Cd and Hg
Sampaio, J. M.; Guerra, M.; Parente, F.; Madeira, T. I.; Indelicato, P.; Santos, J. P.; Marques, J. P.
2016-09-01
In this paper, we calculate the K-, L- and M-shells X-ray production, and X-ray fluorescence cross-sections after photo-induced ionization, for Zn, Cd, and Hg, and for incident photon energy range from 1 to 150 keV. For this purpose, the corresponding average fluorescence yields for Zn, Cd, and Hg as well as the photoionization cross-sections were calculated using the Dirac-Fock method. Subshell fluorescence, intrashell and intershell yields are obtained consistently from radiative and radiationless transitions calculated in the exact same method. A comprehensive account of the relations between the X-ray production, X-ray fluorescence cross-sections and the photoionization cross-sections and these yields is presented. Comparisons are made with results from other authors. The obtained values for the photoionization cross-sections are in good agreement with the widely used data of Scofield in the studied energy range. However our results for the X-ray fluorescence cross sections seem to favor some data relatively to others. The energy dependence of the average fluorescence yields is discussed, in particular, the reliability of extrapolated data for lighter elements from measurements and calculations in heavier elements above the inner shell absorption edges is questioned. Tabulated data on photoionization and X-ray production cross-sections are presented for the incident photon energy range 1-150 keV in steps of 1 keV.
10. CMS results on exclusive and diffractive production
SciTech Connect
Alves, Gilvan A.
2015-04-10
We present recent CMS measurements of diffractive and exclusive processes, using data collected at 7 TeV at the LHC. Measurements of soft single- and double-diffractive cross sections are presented, as well as measurements of photon-induced processes including studies of exclusive WW production via photon-photon exchange.
11. Estimates of Z boson and J/ψ production cross sections at the large hadron collider
SciTech Connect
Alexopoulos, T.; Leontsinis, S.
2015-05-15
We calculate the leading-order cross section for the associated production of Z and J/ψ. Processes that include associated production of electroweak bosons and heavy quarkonium can give valuable insight into the production mechanism of quarkonia. We conclude that this process is accessible by the LHC statistics.
12. Measurement of angular dependence of M X-ray production cross-sections in Re, Bi and U at 5.96 keV
Apaydın, G.; Tıraşoǧlu, E.; Söǧüt, Ã.-.
2008-03-01
The M X-ray production differential cross sections in Re, Bi and U elements have been measured at the 5.96 keV incident photon energy in an angular range 135° 155°. The measurements were performed using a 55Fe source and a Si(Li) detector. The present results contradict the predictions of Cooper and Zare [ Atomic Collision Processes, Gordon and Breach, New York (1969)] and experimental results of Kumar et al. [J. Phys. B: At. Mol. Opt. 34, 613 (2001)]. that, after photoionization of inner shells, the vacancy state has equal population of magnetic substates and the subsequent X-ray emission is isotropic, but confirm the predictions of the calculations of Flügge et al. [Phys. Rev. Lett. 29, 7 (1972)] and experimental results of Sharma and Allawadhi [J. Phys. B: At. Mol. Opt. 32, 2343 (1999)] and Ertugrul [Nucl. Instrum. Meth. B 119, 345 (1996)]. Total M X-ray production cross sections from the decay at the 5.96 keV photon energies are found to be in good agreement with the calculated theoretical results using the theoretical values of M shell photoionization cross section.
13. Lecturers' Perception of Research Activities for Knowledge Production in Universities in Cross River State, Nigeria
ERIC Educational Resources Information Center
Uchendu, C. C.; Osim, R. O.; Odigwe, F. N.; Alade, F. N.
2014-01-01
This study examined lecturers' perception of research activities for knowledge production in universities in Cross River State, Nigeria. Two hypotheses were isolated to give direction to this investigation. 240 university lecturers were sampled from a population of 1,868 from the two universities in Cross River State, using stratified random…
14. Top quark production cross section at E**cm = 1.96-TeV
SciTech Connect
Schwienhorst, Reinhard; /Michigan State U.
2004-11-01
Preliminary results on the top pair production cross section measurements by the D0 and CDF experiments in Run II at the Tevatron are presented. The measurements are obtained using various final state signatures.
15. Qcd physics: measurement of the cross section for prompt diphoton production in p anti-p collisions at s**(1/2) = 1.96 tev
SciTech Connect
Acosta, D.; The CDF Collaboration
2005-06-13
We report a measurement of the rate of prompt diphoton production in p{bar p} collisions at {radical}s = 1.96 TeV using a data sample of 207 pb{sup -1} collected with the upgraded Collider Detector at Fermilab (CDF II). The background from non-prompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.
16. Measurement of the cross section for prompt diphoton production in pp collisions at square root of s=1.96 TeV.
PubMed
Acosta, D; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Arguin, J-F; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Bacchetta, N; Bachacou, H; Badgett, W; Barbaro-Galtieri, A; Barker, G J; Barnes, V E; Barnett, B A; Baroiant, S; Barone, M; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Ben-Haim, E; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bishai, M; Blair, R E; Blocker, C; Bloom, K; Blumenfeld, B; Bocci, A; Bodek, A; Bolla, G; Bolshov, A; Booth, P S L; Bortoletto, D; Boudreau, J; Bourov, S; Brau, B; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canepa, A; Casarsa, M; Carlsmith, D; Carron, S; Carosi, R; Cavalli-Sforza, M; Castro, A; Catastini, P; Cauz, D; Cerri, A; Cerrito, L; Chapman, J; Chen, C; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Chu, M L; Chuang, S; Chung, J Y; Chung, W-H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A G; Clark, D; Coca, M; Connolly, A; Convery, M; Conway, J; Cooper, B; Cordelli, M; Cortiana, G; Cranshaw, J; Cuevas, J; Culbertson, R; Currat, C; Cyr, D; Dagenhart, D; Da Ronco, S; D'Auria, S; de Barbaro, P; De Cecco, S; De Lentdecker, G; Dell'Agnello, S; Dell'Orso, M; Demers, S; Demortier, L; Deninno, M; De Pedis, D; Derwent, P F; Dionisi, C; Dittmann, J R; Dörr, C; Doksus, P; Dominguez, A; Donati, S; Donega, M; Donini, J; D'Onofrio, M; Dorigo, T; Drollinger, V; Ebina, K; Eddy, N; Ehlers, J; Ely, R; Erbacher, R; Erdmann, M; Errede, D; Errede, S; Eusebi, R; Fang, H-C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferretti, C; Field, R D; Flanagan, G; Flaugher, B; Flores-Castillo, L R; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Fujii, Y; Furic, I; Gajjar, A; Gallas, A; Galyardt, J; Gallinaro, M; Garcia-Sciveres, M; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D W; Gerchtein, E; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Ginsburg, C; Giolo, K; Giordani, M; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, D; Goldstein, J; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Gotra, Y; Goulianos, K; Gresele, A; Griffiths, M; Grosso-Pilcher, C; Grundler, U; Guenther, M; Guimaraes da Costa, J; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harr, R F; Harris, R M; Hartmann, F; Hatakeyama, K; Hauser, J; Hays, C; Hayward, H; Heider, E; Heinemann, B; Heinrich, J; Hennecke, M; Herndon, M; Hill, C; Hirschbuehl, D; Hocker, A; Hoffman, K D; Holloway, A; Hou, S; Houlden, M A; Huffman, B T; Huang, Y; Hughes, R E; Huston, J; Ikado, K; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Issever, C; Ivanov, A; Iwata, Y; Iyutin, B; James, E; Jang, D; Jarrell, J; Jeans, D; Jensen, H; Jeon, E J; Jones, M; Joo, K K; Jun, S Y; Junk, T; Kamon, T; Kang, J; Karagoz Unel, M; Karchin, P E; Kartal, S; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, M S; Kim, S B; Kim, S H; Kim, T H; Kim, Y K; King, B T; Kirby, M; Kirsch, L; Klimenko, S; Knuteson, B; Ko, B R; Kobayashi, H; Koehn, P; Kong, D J; Kondo, K; Konigsberg, J; Kordas, K; Korn, A; Korytov, A; Kotelnikov, K; Kotwal, A V; Kovalev, A; Kraus, J; Kravchenko, I; Kreymer, A; Kroll, J; Kruse, M; Krutelyov, V; Kuhlmann, S E; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, J; Lancaster, M; Lander, R; Lannon, K; Lath, A; Latino, G; Lauhakangas, R; Lazzizzera, I; Le, Y; Lecci, C; LeCompte, T; Lee, J; Lee, J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Li, K; Lin, C; Lin, C S; Lindgren, M; Liss, T M; Lister, A; Litvintsev, D O; Liu, T; Liu, Y; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; MacQueen, D; Madrak, R; Maeshima, K; Maksimovic, P; Malferrari, L; Manca, G; Marginean, R; Marino, C; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Matsunaga, H; Mattson, M; Mazzanti, P; McFarland, K S; McGivern, D; McIntyre, P M; McNamara, P; NcNulty, R; Mehta, A; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miller, L; Miller, R; Miller, J S; Miquel, R; Miscetti, S; Mitselmakher, G; Miyamoto, A; Miyazaki, Y; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla Fernandez, P A; Mukherjee, A; Mulhearn, M; Muller, T; Mumford, R; Munar, A; Murat, P; Nachtman, J; Nahn, S; Nakamura, I; Nakano, I; Napier, A; Napora, R; Naumov, D; Necula, V; Niell, F; Nielsen, J; Nelson, C; Nelson, T; Neu, C; Neubauer, M S; Newman-Holmes, C; Nigmanov, T; Nodulman, L; Norniella, O; Oesterberg, K; Ogawa, T; Oh, S H; Oh, Y D; Ohsugi, T; Okusawa, T; Oldeman, R; Orava, R; Orejudos, W; Pagliarone, C; Palencia, E; Paoletti, R; Papadimitriou, V; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Pauly, T; Paus, C; Pellett, D; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pitts, K T; Plager, C; Pompos, A; Pondrom, L; Pope, G; Portell, X; Poukhov, O; Prakoshyn, F; Pratt, T; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Rademacker, J; Rahaman, M A; Rakitine, A; Rappoccio, S; Ratnikov, F; Ray, H; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Rimondi, F; Rinnert, K; Ristori, L; Robertson, W J; Robson, A; Rodrigo, T; Rolli, S; Rosenson, L; Roser, R; Rossin, R; Rott, C; Russ, J; Rusu, V; Ruiz, A; Ryan, D; Saarikko, H; Sabik, S; Safonov, A; Denis, R St; Sakumoto, W K; Salamanna, G; Saltzberg, D; Sanchez, C; Sansoni, A; Santi, L; Sarkar, S; Sato, K; Savard, P; Savoy-Navarro, A; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Scodellaro, L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semeria, F; Sexton-Kennedy, L; Sfiligoi, I; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Siegrist, J; Siket, M; Sill, A; Sinervo, P; Sisakyan, A; Skiba, A; Slaughter, A J; Sliwa, K; Smirnov, D; Smith, J R; Snider, F D; Snihur, R; Soha, A; Somalwar, S V; Spalding, J; Spezziga, M; Spiegel, L; Spinella, F; Spiropulu, M; Squillacioti, P; Stadie, H; Stelzer, B; Stelzer-Chilton, O; Strologas, J; Stuart, D; Sukhanov, A; Sumorok, K; Sun, H; Suzuki, T; Taffard, A; Tafirout, R; Takach, S F; Takano, H; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tanimoto, N; Tapprogge, S; Tecchio, M; Teng, P K; Terashi, K; Tesarek, R J; Tether, S; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tollefson, K; Tomura, T; Tonelli, D; Tönnesmann, M; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tseng, J; Tsuchiya, R; Tsuno, S; Tsybychev, D; Turini, N; Turner, M; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vacavant, L; Vaiciulis, A; Varganov, A; Vataga, E; Vejcik, S; Velev, G; Veszpremi, V; Veramendi, G; Vickey, T; Vidal, R; Vila, I; Vilar, R; Vollrath, I; Volobouev, I; von der Mey, M; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wallny, R; Walter, T; Yamashita, T; Yamamoto, K; Wan, Z; Wang, M J; Wang, S M; Warburton, A; Ward, B; Waschke, S; Waters, D; Watts, T; Weber, M; Wester, W C; Whitehouse, B; Wicklund, A B; Wicklund, E; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolter, M; Worcester, M; Worm, S; Wright, T; Wu, X; Würthwein, F; Wyatt, A; Yagil, A; Yang, C; Yang, U K; Yao, W; Yeh, G P; Yi, K; Yoh, J; Yoon, P; Yorita, K; Yoshida, T; Yu, I; Yu, S; Yu, Z; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zetti, F; Zhou, J; Zsenei, A; Zucchelli, S
2005-07-08
We report a measurement of the rate of prompt diphoton production in pp collisions at square root of s=1.96 TeV using a data sample of 207 pb(-1) collected with the upgraded Collider Detector at Fermilab. The background from nonprompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.
17. New results for a photon-photon collider
SciTech Connect
David Asner et al.
2002-09-26
We present new results from studies in progress on physics at a two-photon collider. We report on the sensitivity to top squark parameters of MSSM Higgs boson production in two-photon collisions; Higgs boson decay to two photons; radion production in models of warped extra dimensions; chargino pair production; sensitivity to the trilinear Higgs boson coupling; charged Higgs boson pair production; and we discuss the backgrounds produced by resolved photon-photon interactions.
18. Crossed cerebellar diaschisis in ischemic stroke: a study of regional cerebral blood flow by /sup 133/Xe inhalation and single photon emission computerized tomography
SciTech Connect
Meneghetti, G.; Vorstrup, S.; Mickey, B.; Lindewald, H.; Lassen, N.A.
1984-06-01
Seventy measurements of CBF were performed in 12 stroke patients by /sup 133/Xe inhalation and a rapidly rotating single photon emission computerized tomograph. CBF was measured every other day during the acute phase and at 2- and 6-month follow-up visits. A persistent contralateral cerebellar blood flow depression was evident in five patients with severe hemispheric low flow areas, which correlated with large, hypodense lesions on the computerized tomographic scan. In a sixth patient with a small, deep infarct, a transient crossed cerebellar low flow was observed, while the clinical symptoms persisted. It is concluded from this serial study that crossed cerebellar diaschisis is a common finding in completed stroke. It is probably caused by disconnection of the corticopontine pathways, a disconnection that tends to persist. The phenomenon is in fact less variable than the stroke-related CBF changes in the infarcted hemisphere, in which a period of relative hyperemia is frequently seen.
19. Photoproduction total cross section and shower development
Cornet, F.; García Canal, C. A.; Grau, A.; Pancheri, G.; Sciutto, S. J.
2015-12-01
The total photoproduction cross section at ultrahigh energies is obtained using a model based on QCD minijets and soft-gluon resummation and the ansatz that infrared gluons limit the rise of total cross sections. This cross section is introduced into the Monte Carlo system AIRES to simulate extended air showers initiated by cosmic ray photons. The impact of the new photoproduction cross section on common shower observables, especially those related to muon production, is compared with previous results.
20. Partial dissociative emission cross sections and product state distributions of the resulting photofragments
Picconi, David; Grebenshchikov, Sergy Yu.
2016-12-01
This paper relates the partial cross section of a continuous optical emission into a given scattering channel of the lower electronic state to the photofragment population. This allows one to infer partial emission cross sections 'non-optically' from product state distributions; in computations, explicit construction of exact scattering states is therefore avoided. Applications to the emission spectra of NaI, CO2, and pyrrole are given. It is also demonstrated that a similar relationship holds between partial cross sections of dissociative photoionization and distributions of ionic fragments over final product channels.
1. Parameterized Cross Sections for Pion Production in Proton-Proton Collisions
NASA Technical Reports Server (NTRS)
Blattnig, Steve R.; Swaminathan, Sudha R.; Kruger, Adam T.; Ngom, Moussa; Norbury, John W.; Tripathi, R. K.
2000-01-01
An accurate knowledge of cross sections for pion production in proton-proton collisions finds wide application in particle physics, astrophysics, cosmic ray physics, and space radiation problems, especially in situations where an incident proton is transported through some medium and knowledge of the output particle spectrum is required when given the input spectrum. In these cases, accurate parameterizations of the cross sections are desired. In this paper much of the experimental data are reviewed and compared with a wide variety of different cross section parameterizations. Therefore, parameterizations of neutral and charged pion cross sections are provided that give a very accurate description of the experimental data. Lorentz invariant differential cross sections, spectral distributions, and total cross section parameterizations are presented.
2. Soft X-ray irradiation of methanol ice: Formation of products as a function of photon energy
SciTech Connect
Chen, Y.-J.; Juang, K.-J.; Yih, T.-S.; Ciaravella, A.; Cecchi-Pestellini, C.; Muñoz Caro, G. M.; Jiménez-Escobar, A.
2013-12-01
Pure methanol ices have been irradiated with monochromatic soft X-rays of 300 and 550 eV close to the 1s resonance edges of C and O, respectively, and with a broadband spectrum (250-1200 eV). The infrared (IR) spectra of the irradiated ices show several new products of astrophysical interest such as CH{sub 2}OH, H{sub 2}CO, CH{sub 4}, HCOOH, HCOCH{sub 2}OH, CH{sub 3}COOH, CH{sub 3}OCH{sub 3}, HCOOCH{sub 3}, and (CH{sub 2}OH){sub 2}, as well as HCO, CO, and CO{sub 2}. The effect of X-rays is the result of the combined interactions of photons and electrons with the ice. A significant contribution to the formation and growth of new species in the CH{sub 3}OH ice irradiated with X-rays is given by secondary electrons, whose energy distribution depends on the energy of X-ray photons. Within a single experiment, the abundances of the new products increase with the absorbed energy. Monochromatic experiments show that product abundances also increase with the photon energy. However, the abundances per unit energy of newly formed species show a marked decrease in the broadband experiment as compared to irradiations with monochromatic photons, suggesting a possible regulatory role of the energy deposition rate. The number of new molecules produced per absorbed eV in the X-ray experiments has been compared to those obtained with electron and ultraviolet (UV) irradiation experiments.
3. Suitability of cross-bred cows for organic farms based on cross-breeding effects on production and functional traits.
PubMed
de Haas, Y; Smolders, E A A; Hoorneman, J N; Nauta, W J; Veerkamp, R F
2013-04-01
Data from 113 Dutch organic farms were analysed to determine the effect of cross-breeding on production and functional traits. In total, data on 33 788 lactations between January 2003 and February 2009 from 15 015 cows were available. Holstein-Friesian pure-bred cows produced most kg of milk in 305 days, but with the lowest percentages of fat and protein of all pure-bred cows in the data set. Cross-breeding Holstein dairy cows with other breeds (Brown Swiss, Dutch Friesian, Groningen White Headed, Jersey, Meuse Rhine Yssel, Montbéliarde or Fleckvieh) decreased milk production, but improved fertility and udder health in most cross-bred animals. In most breeds, heterosis had a significant effect (P < 0.05) on milk (kg in 305 days), fat and protein-corrected milk production (kg in 305 days) and calving interval (CI) in the favourable direction (i.e. more milk, shorter CI), but unfavourably for somatic cell count (higher cell count). Recombination was unfavourable for the milk production traits, but favourable for the functional traits (fertility and udder health). Farm characteristics, like soil type or housing system, affected the regression coefficients on breed components significantly. The effect of the Holstein breed on milk yield was twice as large in cubicle housing as in other housing systems. Jerseys had a negative effect on fertility only on farms on sandy soils. Hence, breed effects differ across farming systems in the organic farming and farmers can use such information to dovetail their farming system with the type of cow they use.
4. Cross-cultural and cross-ecotype production of a killer whale 'excitement' call suggests universality.
PubMed
Rehn, Nicola; Filatova, Olga A; Durban, John W; Foote, Andrew D
2011-01-01
Facial and vocal expressions of emotion have been found in a number of social mammal species and are thought to have evolved to aid social communication. There has been much debate about whether such signals are culturally inherited or are truly biologically innate. Evidence for the innateness of such signals can come from cross-cultural studies. Previous studies have identified a vocalisation (the V4 or 'excitement' call) associated with high arousal behaviours in a population of killer whales in British Columbia, Canada. In this study, we compared recordings from three different socially and reproductively isolated ecotypes of killer whales, including five vocal clans of one ecotype, each clan having discrete culturally transmitted vocal traditions. The V4 call was found in recordings of each ecotype and each vocal clan. Nine independent observers reproduced our classification of the V4 call from each population with high inter-observer agreement. Our results suggest the V4 call may be universal in Pacific killer whale populations and that transmission of this call is independent of cultural tradition or ecotype. We argue that such universality is more consistent with an innate vocalisation than one acquired through social learning and may be linked to its apparent function of motivational expression.
5. Cross-cultural and cross-ecotype production of a killer whale excitement' call suggests universality
Rehn, Nicola; Filatova, Olga A.; Durban, John W.; Foote, Andrew D.
2011-01-01
Facial and vocal expressions of emotion have been found in a number of social mammal species and are thought to have evolved to aid social communication. There has been much debate about whether such signals are culturally inherited or are truly biologically innate. Evidence for the innateness of such signals can come from cross-cultural studies. Previous studies have identified a vocalisation (the V4 or `excitement' call) associated with high arousal behaviours in a population of killer whales in British Columbia, Canada. In this study, we compared recordings from three different socially and reproductively isolated ecotypes of killer whales, including five vocal clans of one ecotype, each clan having discrete culturally transmitted vocal traditions. The V4 call was found in recordings of each ecotype and each vocal clan. Nine independent observers reproduced our classification of the V4 call from each population with high inter-observer agreement. Our results suggest the V4 call may be universal in Pacific killer whale populations and that transmission of this call is independent of cultural tradition or ecotype. We argue that such universality is more consistent with an innate vocalisation than one acquired through social learning and may be linked to its apparent function of motivational expression.
6. Measurement of differential cross sections for Higgs boson production in the diphoton decay channel in pp collisions at [Formula: see text].
PubMed
A measurement is presented of differential cross sections for Higgs boson (H) production in pp collisions at [Formula: see text][Formula: see text]. The analysis exploits the [Formula: see text] decay in data corresponding to an integrated luminosity of 19.7[Formula: see text] collected by the CMS experiment at the LHC. The cross section is measured as a function of the kinematic properties of the diphoton system and of the associated jets. Results corrected for detector effects are compared with predictions at next-to-leading order and next-to-next-to-leading order in perturbative quantum chromodynamics, as well as with predictions beyond the standard model. For isolated photons with pseudorapidities [Formula: see text], and with the photon of largest and next-to-largest transverse momentum ([Formula: see text]) divided by the diphoton mass [Formula: see text] satisfying the respective conditions of [Formula: see text] and [Formula: see text], the total fiducial cross section is [Formula: see text][Formula: see text].
7. Measurement of differential cross sections for Higgs boson production in the diphoton decay channel in pp collisions at $$\\sqrt{s}$$ = 8 TeV
DOE PAGES
Khachatryan, Vardan
2016-01-11
Here, we presented a measurement of differential cross sections for the Higgs boson (H) production in pp collisions at √s = 8 TeV. The analysis exploits the H →γγ decay in data corresponding to an integrated luminosity of 19.7 fb-1 collected by the CMS experiment at the LHC. The cross section is measured as a function of the kinematic properties of the diphoton system and of the associated jets. Results corrected for detector effects are compared with predictions at next-to-leading order and nextto-next-to-leading order in perturbative quantum chromodynamics, as well as with predictions beyond the standard model. Furthermore, for isolatedmore » photons with pseudorapidities |η| < 2.5, and with the photon of largest and next-to-largest transverse momentum (pγT) divided by the diphoton mass mgg satisfying the respective conditions of pγT/mγγ > 1/3 and >1/4, the total fiducial cross section is 32 ±10 fb.« less
8. Measurement of differential cross sections for Higgs boson production in the diphoton decay channel in pp collisions at $\\sqrt{s}$ = 8 TeV
SciTech Connect
Khachatryan, Vardan
2016-01-11
Here, we presented a measurement of differential cross sections for the Higgs boson (H) production in pp collisions at √s = 8 TeV. The analysis exploits the H →γγ decay in data corresponding to an integrated luminosity of 19.7 fb-1 collected by the CMS experiment at the LHC. The cross section is measured as a function of the kinematic properties of the diphoton system and of the associated jets. Results corrected for detector effects are compared with predictions at next-to-leading order and nextto-next-to-leading order in perturbative quantum chromodynamics, as well as with predictions beyond the standard model. Furthermore, for isolated photons with pseudorapidities |η| < 2.5, and with the photon of largest and next-to-largest transverse momentum (pγT) divided by the diphoton mass mgg satisfying the respective conditions of pγT/mγγ > 1/3 and >1/4, the total fiducial cross section is 32 ±10 fb.
9. Measurement of the cross section for high-pT hadron production in the scattering of 160-GeV/c muons off nucleons
Adolph, C.; Alekseev, M. G.; Alexakhin, V. Yu.; Alexandrov, Yu.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Austregesilo, A.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bertini, R.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M., Jr.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Goertz, S.; Grabmüller, S.; Grasso, A.; Grube, B.; Gushterski, R.; Guskov, A.; Guthörl, T.; Haas, F.; von Harrach, D.; Heinsius, F. H.; Herrmann, F.; Heß, C.; Hinterberger, F.; Höppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Morreale, A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Novakova, C.; Novy, J.; Nowak, W.-D.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Pesek, M.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Reicherz, G.; Rocco, E.; Rodionov, V.; Rondio, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sapozhnikov, M. G.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, A.; Schmidt, K.; Schmïden, H.; Schmitt, L.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Sznajder, P.; Takekawa, S.; Ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vondra, J.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wiślicki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.
2013-11-01
The differential cross section for the production of charged hadrons with high transverse momenta in the scattering of 160GeV/c muons off nucleons at low photon virtualities has been measured at the COMPASS experiment at CERN. The results, which cover transverse momenta from 1.1GeV/c to 3.6GeV/c, are compared to a perturbative quantum chromodynamics (pQCD) calculation, in order to evaluate the applicability of pQCD to this process in the kinematic domain of the experiment. The shape of the calculated differential cross section as a function of transverse momentum is found to be in good agreement with the experimental data, but the absolute scale is underestimated by next-to-leading order pQCD. The inclusion of all-order resummation of large logarithmic threshold corrections reduces the discrepancy from a factor of 3 to 4 to a factor of 2. The dependence of the cross section on the pseudorapidity and on the virtual photon energy fraction is investigated. Finally the dependence on the charge of the hadrons is discussed.
10. Graphs of the cross sections in the recommended Monte Carlo cross-section library at the Los Alamos Scientific Laboratory
SciTech Connect
Soran, P.D.; Seamon, R.E.
1980-05-01
Graphs of all neutron cross sections and photon production cross sections on the Recommended Monte Carlo Cross Section (RMCCS) library have been plotted along with local neutron heating numbers. Values for anti ..nu.., the average number of neutrons per fission, are also given.
11. Jacobian transformed and detailed balance approximations for photon induced scattering
Wienke, B. R.; Budge, K. G.; Chang, J. H.; Dahl, J. A.; Hungerford, A. L.
2012-01-01
Photon emission and scattering are enhanced by the number of photons in the final state, and the photon transport equation reflects this in scattering-emission kernels and source terms. This is often a complication in both theoretical and numerical analyzes, requiring approximations and assumptions about background and material temperatures, incident and exiting photon energies, local thermodynamic equilibrium, plus other related aspects of photon scattering and emission. We review earlier schemes parameterizing photon scattering-emission processes, and suggest two alternative schemes. One links the product of photon and electron distributions in the final state to the product in the initial state by Jacobian transformation of kinematical variables (energy and angle), and the other links integrands of scattering kernels in a detailed balance requirement for overall (integrated) induced effects. Compton and inverse Compton differential scattering cross sections are detailed in appropriate limits, numerical integrations are performed over the induced scattering kernel, and for tabulation induced scattering terms are incorporated into effective cross sections for comparisons and numerical estimates. Relativistic electron distributions are assumed for calculations. Both Wien and Planckian distributions are contrasted for impact on induced scattering as LTE limit points. We find that both transformed and balanced approximations suggest larger induced scattering effects at high photon energies and low electron temperatures, and smaller effects in the opposite limits, compared to previous analyzes, with 10-20% increases in effective cross sections. We also note that both approximations can be simply implemented within existing transport modules or opacity processors as an additional term in the effective scattering cross section. Applications and comparisons include effective cross sections, kernel approximations, and impacts on radiative transport solutions in 1D
12. Exploratory study of fission product yield determination from photofission of Pu239 at 11 MeV with monoenergetic photons
DOE PAGES
Bhike, Megha; Tornow, W.; Krishichayan, -; ...
2017-02-14
Here, measurements of fission product yields play an important role for the understanding of fundamental aspects of the fission process. Recently, neutron-induced fission product-yield data of 239Pu at energies below 4 MeV revealed an unexpected energy dependence of certain fission fragments. In order to investigate whether this observation is prerogative to neutron-induced fission, a program has been initiated to measure fission product yields in photoinduced fission. Here we report on the first ever photofission product yield measurement with monoenergetic photons produced by Compton back-scattering of FEL photons. The experiment was performed at the High-Intensity Gamma-ray Source at Triangle Universities Nuclear Laboratory on 239Pu at Eγmore » = 11 MeV. In this exploratory study the yield of eight fission products ranging from 91Sr to 143Ce has been obtained.« less
13. Measurement of 230Pa and 186Re Production Cross Sections Induced by Deuterons at Arronax Facility
2014-02-01
A dedicated program has been launched on production of innovative radionuclides for PET imaging and for β- and α targeted radiotherapy using proton or α particles at the ARRONAX cyclotron. Since the accelerator is also able to deliver deuteron beams up to 35 MeV, we have reconsidered the possibility of using them to produce medical isotopes. Two isotopes dedicated to targeted therapy have been considered: 226Th, a decay product of 230Pa, and 186Re. The production cross sections of 230Pa and 186Re, as well as those of the contaminants created during the irradiation, have been determined by the stacked-foil technique using deuteron beams. Experimental values have been quantified using a referenced cross section. The measured cross sections have been used to determine expected production yields and compared with the calculated values obtained using the Talys code with default parameters.
14. Measurement of the Zγ → ν ν ‾ γ production cross section in pp collisions at √{ s} = 8 TeV and limits on anomalous ZZγ and Zγγ trilinear gauge boson couplings
2016-09-01
An inclusive measurement of the Zγ → ν ν ‾ γ production cross section in pp collisions at √{ s} = 8TeV is presented, using data corresponding to an integrated luminosity of 19.6 fb-1 collected with the CMS detector at the LHC. This measurement is based on the observation of events with large missing energy and with a single photon with transverse momentum above 145GeV and absolute pseudorapidity in the range | η | < 1.44. The measured Zγ → ν ν ‾ γ production cross section, 52.7 ± 2.1 (stat) ± 6.4 (syst) ± 1.4 (lumi) fb, agrees well with the standard model prediction of 50.0-2.2+2.4 fb. A study of the photon transverse momentum spectrum yields the most stringent limits to date on the anomalous ZZγ and Zγγ trilinear gauge boson couplings.
15. Search for production of resonant states in the photon-jet mass distribution using pp collisions at √s=7 TeV collected by the ATLAS detector.
PubMed
2012-05-25
This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11 fb(-1) of proton-proton collisions at √s=7 TeV. We compare the photon+jet mass distribution to a background model derived from data and find consistency with the background-only hypothesis. Given the lack of evidence for a signal, we set 95% credibility level limits on generic Gaussian-shaped signals and on a benchmark excited-quark (q*) model, excluding 2 TeV Gaussian resonances with cross section times branching fraction times acceptance times efficiency near 5 fb and excluding q* masses below 2.46 TeV, respectively.
16. Spatio-energetic cross-talks in photon counting detectors: detector model and correlated Poisson data generator
Taguchi, Katsuyuki; Polster, Christoph; Lee, Okkyun; Kappler, Steffen
2016-03-01
An x-ray photon interacts with photon counting detectors (PCDs) and generates an electron charge cloud or multiple clouds. The clouds (thus, the photon energy) may be split between two adjacent PCD pixels when the interaction occurs near pixel boundaries, producing a count at both of the two pixels. This is called double-counting with charge sharing. The output of individual PCD pixel is Poisson distributed integer counts; however, the outputs of adjacent pixels are correlated due to double-counting. Major problems are the lack of detector noise model for the spatio-energetic crosstalk and the lack of an efficient simulation tool. Monte Carlo simulation can accurately simulate these phenomena and produce noisy data; however, it is not computationally efficient. In this study, we developed a new detector model and implemented into an efficient software simulator which uses a Poisson random number generator to produce correlated noisy integer counts. The detector model takes the following effects into account effects: (1) detection efficiency and incomplete charge collection; (2) photoelectric effect with total absorption; (3) photoelectric effect with fluorescence x-ray emission and re-absorption; (4) photoelectric effect with fluorescence x-ray emission which leaves PCD completely; and (5) electric noise. The model produced total detector spectrum similar to previous MC simulation data. The model can be used to predict spectrum and correlation with various different settings. The simulated noisy data demonstrated the expected performance: (a) data were integers; (b) the mean and covariance matrix was close to the target values; (c) noisy data generation was very efficient
17. Systematics of isotopic production cross sections from interactions of relativistic {sup 40}Ca in hydrogen
SciTech Connect
Chen, C.; Guzik, T.G.; McMahon, M.; Wefel, J.P.; Albergo, S.; Caccia, Z.; Costa, S.; Insolia, A.; Potenza, R.; Russo, G.V.; Tuve, C.; Crawford, H.J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Knott, C.N.; Waddington, C.J.; Lindstrom, P.J.; Tull, C.E.; Mitchell, J.W.; Webber, W.R.
1997-09-01
The isotopic production cross sections for {sup 40} Ca projectiles at 357, 565, and 763 MeV/nucleon interacting in a liquid hydrogen target have been measured by the Transport Collaboration at the LBL HISS facility. The systematics of these cross sections are studied, and the results indicate that nuclear structure effects are present in the isotope production process during the relativistic collisions. The newly measured cross sections are also compared with those predicted by semiempirical and parametric formulas, but the predictions do not fully describe the systematics such as the energy dependence. The consequences of the cross section systematics in galactic cosmic ray studies are also discussed. {copyright} {ital 1997} {ital The American Physical Society}
18. Interactions of relativistic neon to nickel projectiles in hydrogen, elemental production cross sections
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https://www.physicsforums.com/threads/level-curves.184021/
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# Homework Help: Level curves
1. Sep 11, 2007
### cscott
1. The problem statement, all variables and given/known data
I need to sketch level curves of $T(x, y) = 50(1 + x^2 + 3y^2)^{-1}$ and $V(x, y) = \sqrt{1 - 9x^2 -4y^2}$
3. The attempt at a solution
Is it correct that they are ellipses?
ie $$1 = \frac{9}{1 - c^2} x^2 + \frac{4}{1 - c^2}y^2[/itex] for V(x, y) = c = constant I feel so rusty going back to school :s Last edited: Sep 11, 2007 2. Sep 11, 2007 ### HallsofIvy That's for V? Setting $V(x,y)= \sqrt{1- 9x^2- 4y^2}= c$, then $1- 9x^2- 4y^2= c^2$, $9x^2+ 4y^2= 1-c^2$, [tex]\frac{9}{1- c^2}x^2+ \frac{4}{1-c^2}y^2= 1$$
just as you say. Yes, that's an ellipse. It might be easier to recognise if you wrote it
$$\frac{x^2}{\left(\frac{\sqrt{1-c^2}}{3}\right)^2}+ \frac{y^2}{\left(\frac{\sqrt{1-c^2}}{2}\right)^2}= 1$$
an ellipse with center at (0,0) and semi-axes of length
$$\frac{\sqrt{1-c^2}}{3}$$
and
$$\frac{\sqrt{1-c^2}}{2}$$
Similarly, $T(x,y)= 50(1+ x^2+ 3y^2)^{-1}= c$ gives $c(1+ x^2+ 3y^2)= 50$ so $1+ x^2+ 3y^2= 50/c$, $x^2+ 3y^2= (50/c- 1)$. Now divide both sides by 50/c- 1:
$$\frac{x^2}{50/c-1}+ \frac{y^2}{\frac{50/c-1}{3}}= 1$$
again, an ellipse with center at (0,0), semi-axes of length
$$\sqrt{50/c- 1}$$
and
$$\sqrt{\frac{50/c- 1}{3}}$$
3. Sep 11, 2007
### cscott
That does make it easier to understand.
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http://www.sciforums.com/threads/manipulating-electrons-and-quarks-to-negate-gravity.160454/page-3
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# manipulating electrons and quarks to negate gravity
Discussion in 'Pseudoscience' started by Kevin paul wood, Jan 14, 2018.
1. ### NotEinsteinValued Senior Member
Messages:
1,496
So the first sentence of your opening post was incorrect? OK.
What resonance are you referring to exactly?
What are "multi spatial properties"?
The oscillations of what field exactly?
How can mass be excited to a frequency?
Again, what does "winking out" mean?
Aha, so it is producing a force to counter gravity, not to remove the force of gravity. Got it.
How does this force know which direction gravity is operating in? All forces relevant at the atomic scale I know of do not couple with gravity in this way.
What does it mean to "hoodwink gravity"?
What does it mean to "slip a mass a millisecond out of time"?
All of this is starting to sound more and more like word-salad. Perhaps this thread should be moved into the fringe-subsection of this forum. (And it seems exchemist agrees.)
(That is not my nickname; please type it correctly.)
Since "electron quasiparticle entrophic entangelment einstines spooky theory at work" is gibberish and thus doesn't exist, no, I don't think that has anything to do with it.
3. ### Kevin paul woodRegistered Member
Messages:
32
the electrons are constantly vibrating to some degree and if you want to get technical evrything has a resonate frequency and its pseudo quasiparticle entangelment via entropic electron and bozeon
5. ### Kevin paul woodRegistered Member
Messages:
32
it means the electron goes back to its normal state of evrywhere and nowhere now and anytime inside the atom thats its spacial anomoly r you fucking with me or testing me because i will eat shit to learn but not if your making light you have to know this is big
7. ### Kevin paul woodRegistered Member
Messages:
32
i dont care when i get the nobel i wont even thik of you two i can explain this to anyone with a 100 iq you arent going to teach me shit are ya
8. ### NotEinsteinValued Senior Member
Messages:
1,496
If you are talking about the thermal vibrations, then yes (when not at absolute zero temperature), that's correct.
Everything solid, sure.
That is gibberish; you appear to just be stringing words together, resulting in a meaningless word-salad.
The normal state of an electron doesn't say that the electron is everywhere, nor that is it nowhere (and how can it be both at the same time anyway?), nor that it is anytime.
If that's the normal state, it's not an anomaly. Also, if it's "now and anytime", wouldn't it be a temporal anomaly too?
No, I'm not f*cking with you; either there is a language barrier, or you appear to be using words and terminology differently than mainstream science. I'm just trying to understand what you mean; no need to get insulting.
I am not; I'm just trying to understand what you are saying.
You should; if other people cannot understand what you are saying, you are not going to convince other people of the correctness of your claims.
If you are merely following the work of Edward Leedskalnin, I think the Nobel Prize would be awarded to him. However, the Nobel Prize isn't awarded posthumously, so that's not going to happen either, I'm afraid.
Good, letting things go is an important skill to have.
I suppose that could be contrived to be an insult of my intelligence... Good thing you don't know my actual IQ, so your statement clearly doesn't refer to me.
(Again, please watch your language.) I'm not trying to teach you anything; I'm trying to get you to teach me.
Messages:
10,450
OK.
10. ### hardaleeRegistered Senior Member
Messages:
381
I have been to coral castle along us1 south of Miami many years ago.
It is interesting but not a feat requiring new science.
It was built with pulleys, levers, inclined planes, etc. that were available to builders and engineers at the time.
No mystery to a structural engineer but worth the price of admission.
11. ### river
Messages:
11,058
Hmm...
Yet nobody saw any evidence of any of these devices .
12. ### originIn a democracy you deserve the leaders you elect.Valued Senior Member
Messages:
10,450
There is no evidence of any devices used to construct or erect the Statue of Liberty, Hmm
13. ### RainbowSingularityValued Senior Member
Messages:
1,094
just guessing here but if you apply an anti matter force that ocilates a wave function to form a cantilever force that pushes back against gravity, then E=MC2 is not butt hurt.
... kinda like gravitational lensing with magnets
but i am just postulising
*magnets being a harmonic field resonance generator of some variety
14. ### NotEinsteinValued Senior Member
Messages:
1,496
What is an "anti matter force"?
Is the wave function oscillating, or is the force causing an oscillation of the wave function?
What does gravity have to do with this? Gravity is an insignificant force at this scale, compared to the electromagnetic and strong interaction forces.
Why would anything violate $E=mc^2$ in the first place?
How is an anti matter force similar to the magnetic force?
Honestly, it looks more like word-salad to me...
In what way are magnets "harmonic field generators of some variety"?
15. ### RainbowSingularityValued Senior Member
Messages:
1,094
you are not usualy honest ?
16. ### NotEinsteinValued Senior Member
Messages:
1,496
Where have I said that?
17. ### RainbowSingularityValued Senior Member
Messages:
1,094
(penny drops)
99.99999% have absolutely NO intention of teaching you anything.
there is haggling
there is shouting
there is teaching
chance of #3 is around 0.00001%
here.
thus everything above what you have just labelled as honest,
all content from before the point you started being honest
18. ### NotEinsteinValued Senior Member
Messages:
1,496
Ah, I see where your confusion is coming from. In English, it's a sort of short-hand for "In my honest opinion" (at least, that's how I've been taught it). I prefaced that sentence to make it explicitly clear that I was just giving my opinion at the time.
I see you've chosen to ignore my other questions? What is your opinion on the "intellectual honesty" of a person doing that?
19. ### RainbowSingularityValued Senior Member
Messages:
1,094
realising the importance of the use of language in scientific terms you have decided to flog a dead horse that you lead to water then shot because it asked if there was a different flavour water availible.
the "flogging" part of your post is "shouting" the same thing "etherial honesty" as a metaphor to subframe the debate into a pre coded version of what you intend to pull out of it.
20. ### RainbowSingularityValued Senior Member
Messages:
1,094
the application of the technical specificity is important ?
thus injecting the term "honesty" should suddenly be translated into something else ?
... ?
of "any" variety ?
intellectualy honest ?
you appear to be trolling.
i look forward to you proving me wrong.
Last edited: Jun 6, 2018
21. ### DaveC426913Valued Senior Member
Messages:
9,184
Polite people try not to be too honest when it comes to criticizing. Reticence is the better part of manners.
All of NE's comments were polite, but the one about word salad was his reticence cracking, and having to criticize KPW's comment.
A perfectly legitimate use of the word 'honestly'.
22. ### DaveC426913Valued Senior Member
Messages:
9,184
NE is doing what can only be described as the very opposite of trolling.
He is patiently, and politely attempting to get KPW's to explain his comments so that he can address them.
KPW is indeed using words and phrases that are, to be generous, scientifically ambiguous.
KPW should be encouraged to nurture his interest in science, but should also be encouraged to learn that the way to a Nobel prize is by educating himself in the area of his interest, so as to meaningfully ask questions.
If anyone could be accused the trolling, it might be you, for trying to take the conversation toward attacking another member who is engaged in a discussion. Don't be that guy.
exchemist likes this.
23. ### RainbowSingularityValued Senior Member
Messages:
1,094
i conceed your points to err on my ignorance while accepting your greater comprehention of NE's meanings.
noting some subjects are off limits...
suffice to say the magic of magnets & harmonic reasonance production manipulation etc is quite a fringe science.
having lightly read on the coral castle it could have been built by mexican slave labour for all we know.
noting if it were possible to produce gravity, thus it possible to produce a gravity field(of some type)
"Gravity" being quite the scientific mystery box etc... bosons etc... is harmonic reasonance subject to gravitational influence & vice versa
right out on the fringe for an example were it possible to produce cold fusion in a cell phone size machine it might open up mechanics of things that currently appear outside the known range of newtonian physics.
how long did it take for the global corporate science department to decide cell phone towers were probably not too awfully bad for anyone as long as they dont put one in the CEOs' back yard...
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https://www.physicsforums.com/threads/second-order-geodesic-equation.725793/
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# Second order geodesic equation.
1. Nov 30, 2013
### ozone
Hello all,
I have a geodesic equation from extremizing the action which is second order. I am curious as to what the significance is of having 2 independent geodesic equations is. Also I was wondering what the best way to deal with this is.
2. Nov 30, 2013
### WannabeNewton
What do you mean by two independent geodesic equations? Are you working in a 2 dimensional space with coordinates $\{x^1,x^2\}$ and have two geodesic equations, one for each coordinate?
As an aside, usually the easiest way to deal with the geodesic equation is to not deal with it at all. What I mean by this is that if your space has obvious symmetries then just use first integrals of conserved quantities. It's the same thing as using conservation of energy instead of Newton's 2nd law for classical mechanics problems.
3. Nov 30, 2013
### ozone
Sorry I should have been more clear, I believe that I have two independent solutions to the geodesic equation for a single direction, but perhaps I am misinterpreting the result. The equation is written as
$\ddot{x}(\tau)^a = A_{ab}(\tau) x(\tau)^b$
Here a,b are the two orthogonal directions to the wavefront of a pp-wave. Luckily I am in a system where $A_{ab}$ is an orthogonal matrix. This was derived using some symmetries and conversations with the Lagrangian. However I am having trouble interpreting what it means to have a second order geodesic equation (when we write down our geodesic equation in terms of Christoffel symbols it is always first order).
4. Nov 30, 2013
### WannabeNewton
Perhaps we're using different definitions of the geodesic equation but AFAIK it is always second order in $\tau$: $\ddot{x}^{\mu} = -\Gamma ^{\mu}_{\alpha\beta}\dot{x}^{\alpha}\dot{x}^{\beta}$.
5. Nov 30, 2013
### ozone
True but the equation above should only have one independent solution as best I can ascertain.. Suppose for simplicity we had a diagonal connection coefficient which is valued at 1 in some $\bar{x}$direction, I don't see how that is different from writing $\dot{x}= x^2$ (by substituting$x = \dot{\bar{x}}$),this is only a first order equation... or am I missing something blatant?
6. Dec 2, 2013
### Bill_K
This is one of the standard tricks/methods for solving differential equations. Define p = dx/dt and hope that you can write a DE containing p alone. If so, it will be first order and you can solve it to get p(t). There will be one constant of integration.
But then you still have to solve p = dx/dt to get x(t), and this will produce a second constant of integration. It's a second order DE, you haven't changed that, all you have done is to solve it in stages.
7. Dec 2, 2013
### ozone
Fair enough, I agree with what you are saying. My main question then is what do we do with these constants of integration? May we just arbitrarily set them equal to one?
8. Dec 2, 2013
### Bill_K
E.g. they can be used to specify the two initial conditions for the geodesic: the initial position and velocity.
Similar Discussions: Second order geodesic equation.
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http://codeforces.com/problemset/problem/613/A
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A. Peter and Snow Blower
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Peter got a new snow blower as a New Year present. Of course, Peter decided to try it immediately. After reading the instructions he realized that it does not work like regular snow blowing machines. In order to make it work, you need to tie it to some point that it does not cover, and then switch it on. As a result it will go along a circle around this point and will remove all the snow from its path.
Formally, we assume that Peter's machine is a polygon on a plane. Then, after the machine is switched on, it will make a circle around the point to which Peter tied it (this point lies strictly outside the polygon). That is, each of the points lying within or on the border of the polygon will move along the circular trajectory, with the center of the circle at the point to which Peter tied his machine.
Peter decided to tie his car to point P and now he is wondering what is the area of the region that will be cleared from snow. Help him.
Input
The first line of the input contains three integers — the number of vertices of the polygon n (), and coordinates of point P.
Each of the next n lines contains two integers — coordinates of the vertices of the polygon in the clockwise or counterclockwise order. It is guaranteed that no three consecutive vertices lie on a common straight line.
All the numbers in the input are integers that do not exceed 1 000 000 in their absolute value.
Output
Print a single real value number — the area of the region that will be cleared. Your answer will be considered correct if its absolute or relative error does not exceed 10 - 6.
3 0 00 1-1 21 2
12.566370614359172464
4 1 -10 01 22 01 1
21.991148575128551812
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http://www.computer.org/csdl/proceedings/hicss/2003/1874/09/187490301b-abs.html
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Subscribe
Big Island, HI, USA
Jan. 6, 2003 to Jan. 9, 2003
ISBN: 0-7695-1874-5
pp: 301b
Qun Li , Dartmouth College
Javed Aslam , Dartmouth College
Daniela Rus , Dartmouth College
ABSTRACT
This paper discusses several distributed power-aware routing protocols in wireless ad-hoc networks (especially sensor networks). We seek to optimize the lifetime of the network. We have developed three distributed power-aware algorithms and analyzed their efficiency in terms of the number of message broadcasts and the overall network lifetime modeled as the time to the first message that can not be sent. These are: (1) a distributed min Power algorithm (modeled on a distributed version of Dijkstra?s algorithm), (2) a distributed max-min algorithm, and (3) the distributed version of our the centralized online max - zP<sub>min</sub> algorithm presented in [12]. The first two algorithms are used to define the third, although they are very interesting and useful on their own for applications where the optimization criterion is the minimum power, respectively the maximum residual power. The distributed max - zP<sub>min</sub> algorithm optimizes the overall lifetime of the network by avoiding nodes of low power, while not using too much total power.
INDEX TERMS
null
CITATION
Qun Li, Javed Aslam, Daniela Rus, "Distributed Energy-conserving Routing Protocols", HICSS, 2003, 36th Hawaii International Conference on Systems Sciences, 36th Hawaii International Conference on Systems Sciences 2003, pp. 301b, doi:10.1109/HICSS.2003.1174850
20 ms
(Ver 2.0)
Marketing Automation Platform
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https://github.com/romen/krambook
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# romen/krambook forked from yogsototh/krambook
Write book in Markdown. Use XeLaTeX to render and be able to use macros.
Ruby Shell
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Failed to load latest commit information. bin content filters include .gitignore Google_webfont.url README.md Rakefile config.rb config.ru config_html.rb
# What is this project?
This project intends to provide you a cool way to write a book.
You write text file using the natural markdown syntax. The book can then be generated as PDF using %xelatex or to an HTML website.
You can see examples of standard end result here:
# Why this project?
## Markdown is easier to read than LaTeX
The best typesetting system I know is LaTeX. Unfortunately LaTeX was created a long time ago and its syntax is full of backslashes. Here is an example of a standard minimal LaTeX document:
\documenttype{article}
\usepackage[utf-8]{inputenc}
\usepackage{fontenc}
\usepackage{amsmath}
... % This is the ritual header
\begin{document} % ---- end of the preamble
\section{First section}
I begin by making a list of bullet points:
\begin{itemize}
\item the first point is
\LaTeX is a bit verbose
\item the second point is
\Latex has \textem{more} \textbackslash{} than Markdown
\item I believe you understood now.
\end{itemize}
\end{document}
To achieve a similar result using a markdown syntax:
First section
=============
I begin by making a list of bullet points:
- the first point is LaTeX is a bit verbose
- the second point is LaTeX has _more_ \ than Markdown
- I believe you understood now
The HTML end result using the markdown will be:
# First section
I begin by making a list of bullet points:
• the first point is LaTeX is a bit verbose
• the second point is LaTeX has more \ than Markdown
• I believe you understood now
Then I believe I don't have to convince more you that the markdown syntax is more natural than the LaTeX one.
## Markdown does not scale
LaTeX has many incredible properties that makes it scalable even for very long document. On the other hand Markdown wasn't created for this purpose. Markdown was done to provide a standard syntax to transform some text file into HTML. Markdown lack many features that many other project have added to it. One of this project is Kramdown. There is many other project that expanded the abilities of Markdown.
But I believe not any of these project is scalable because the power of these language is stricly inferior to the power of the TeX language. In fact TeX is Turing complete -- considering we have the ability to make many compilations until reaching a fixed point.
How can LaTeX be Turing complete? Simply with the power of provided by macros. In LaTeX you can declare macros like this:
\newcommand{\un}{\sum_{n=0}^\infty u_n}
And each time you type:
Here is a formula $\un = \pi$
It will be equivalent to:
Here is a formula $\sum_{n=0}^\infty u_n = \pi$
Imagine a thesis where this formula is present a hundred times and you begin to understand why macros are a necessity for long documents. But in LaTeX you could also declare macros with parameters and that use other declared macros:
\newcommand{\ratlang}[2]{\mathcal{S}_{#1}^{\mathrm{rat}}(#2)}
\newcommand{\sr}[2]{\ratlang{\mathbb{R}}(\Sigma)}
...
Let us denote $\sr$ the class of rationnal stochastic language over $\mathbb{R}$ with alphabet $\Sigma$.
Now you see the power of LaTeX.
There is also another thing that make LaTeX scalable. You can include other source files. This make it easy to separate work and also to work with many other people.
Another good point with LaTeX and markdown is that you write only in text file and you can then version these file using git for example.
The purposes of this project are
• Handle long documents by:
• working with many small and versionnable text files
• generate high-quality PDF and HTML documents.
For now, the power of this superset of kramdown syntax is not Turing complete. You can declare macros, but without any parameters and you cannot use already declared macros inside other macros declaration. But this simple addition to markdown is already powerful enough for most of usage.
# FAQ
### What is the idea of the project?
provide macros for Markdown then transform the text in Latex and generate a pdf file.
### Why not using LaTeX directly?
Simply because LaTeX is verbose and full of backslashes. To prove my point, simply compare a LaTeX and a Markdown file.
LaTeX:
\documenttype{article}
\usepackage[utf-8]{inputenc}
\usepackage{fontenc}
\usepackage{amsmath}
... % This is the ritual header
\begin{document} % ---- end of the preamble
I begin by making a list of bullet points:
\begin{itemize}
\item the first point is
\LaTeX is a bit verbose
\item the second point is
\Latex has \textem{more} \textbackslash{} than Markdown
\item I believe you understood now.
\end{itemize}
\end{document}
Markdown:
I begin by making a list of bullet points:
- the first point is LaTeX is a bit verbose
- the second point is LaTeX has _more_ \ than Markdown
- I believe you understood now
Both file will be generated as:
I begin by making a list of bullet points:
• the first point is LaTeX is a bit verbose
• the second point is LaTeX has more \ than Markdown
• I believe you understood now
### Why macros are so necessary for long documents?
Because without them, Markdown simply does not scale. For example imagine you can't declare \su to be generated as $$\sum_{n=0}^{\infty} u_n$$ in a thesis where this expression is repeated 1000 times.
# Install
If you are reading these lines, chances are great that your system contains all necessary packages. But to resume you have to install:
• LaTeX (more precisely XeLaTeX),
• ruby,
• rake and
• %kramdown[^1].
[^1]: %kramdown is an amelioration of the original markdown format.
To install XeLaTeX, I suggest you to use TexLive full install? But of course you are free to use any other distribution.
You'll need to install ruby and rake. They should be present on your system, but just in case:
[Ubuntu]> sudo apt-get install ruby rake
[Mac OS X]> sudo port install ruby rake
In order to install the %kramdown gem:
gem install kramdown
# How do I write a book using it?
• Edit the config.rb file (set title, author name and pdf filename)
• Create and write files in the content folder. You should write them using the kramdown format. Very close to the Mardown format.
• run rake (or rake compile) to create and show a .pdf file.
Remark: : by default file are sorted by name. I suggest you to name your files and folder with number prefixes. For example like 00_intro.md, 01_section/01_subsection.md, etc... You can make a bit of ruby (search @filelist in the Rakefile file) to change this behaviour.
Of course there is also a
rake clean
and
rake clobber
# Macros
Now you can write the content of your book mostly in %kramdown format. But with some simple additions: macros.
Remark: for now Krambook accept only macros without any parameter. Here are some examples:
%%% simple %%% A Simple Macro %%%
%%% amacro %%% a
macro
on many lines %%%
%%% code %%% ruby: "a"*3 %%%
%%% complex %%% ruby: (1..5).map do |x|
x*x
end.join(" : ") %%%
These transformations will occur on the markdown file before it is transformed in LaTeX.
You can also declare macro that will be processed after the file was transformed in LaTeX.
LLL latex LLL \LaTeX LLL
LLL latex_ LLL \LaTeX{} LLL
In markdown, you simply write %macroname or %code and it will be transformed correctly in your pdf.
# HTML render
To render math properly install MathJax into the site/js directory
|
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|
https://www.worldweatherattribution.org/trends-in-weather-extremes-february-2018/
|
# Trends in weather extremes
#### 28 February, 2018
##### News
Twenty years ago, the trend in annual mean global mean temperature became detectable. Ten years ago, robust regional seasonal mean temperature trends similarly started to emerge. Nowadays, we can see trends even in weather extremes.
Studying these trends is an essential step in the extreme event attribution procedure we use at World Weather Attribution. Over the years, we have collected a fair number of results in these analyses and other articles. In this article, I take a step back and consider global long-term meteorological station data for hot, cold, and wet extremes, and share some thoughts on tropical cyclones and droughts. I make no claims for completeness; there is a lot of literature on this that I do not know.
The obvious first-order hypothesis is that warm extremes are getting warmer and cold extremes less cold. Severe precipitation tends to increase due to the higher moisture content of warmer air. Sea level rise simply heightens storms urges. Other extremes do not have as obvious first-order trends.
The figures are based on GHCN-D station data from NOAA/NCEI and can easily be reproduced on the KNMI Climate Explorer. They have at least 50 years of data and a minimum distance between station of 0.5º. The daily average temperature was chosen, defined as the average of maximum and minimum temperatures. This quantity is less sensitive to changes in observing practices and surroundings than either minimum or maximum temperatures alone, e.g., decreased ventilation due to trees growing affects minimum and maximum temperatures with opposite signs. There are no obvious urban/rural contrasts in the maps, so they mainly reflect large-scale trends.
Note that we compute trends as a function of the smoothed global average temperature, rather than simply time, since our first-order hypotheses are related to warming.
### Heat extremes
In this analysis a heat extreme is simply defined as the highest daily average temperature of the year. Our trend analysis shows that almost everywhere these heat extremes are now warmer than a century ago, following the obvious first-order connection with global average temperature. We encountered two exceptions in our work: in the eastern U.S. heat extremes now are roughly as warm as they were during the Dust Bowl of the 1930s, when the severe drought heightened the temperature of hot days. In India, where there has generally been no trend since the 1970s, we find that increasing air pollution and irrigation counteracted the warming trend due to greenhouse gases over that period (van Oldenborgh et al, 2018). In the rest of the world, the increases are typically large, with the temperature of the hottest day of the year rising much faster than the global mean temperatures in most regions (values above one in Figure 1).
The map of Figure 1 also shows the sparsity of stations with long daily temperature records that are publicly available in the tropics. This is mainly a result of the data being sold commercially. However, in this region, temperature extremes are also often not acknowledged, although there is evidence that they pose a major health hazard (see Gerland et al, 2015 for Africa).
### Cold extremes
For cold extremes, the daily average temperature of the coldest day of the year is considered. Figure 2 shows that these cold events heat up even faster than the heat extremes, up to a factor of five times the global mean temperature (see e.g., van Oldenborgh et al, 2015 and the WWA cold wave analyses). The strongest increases over land are in Siberia and Canada. Winter temperatures are very low there due to radiative cooling over snow under a clear sky, with strong vertical gradients in the lowest meters of the atmosphere. These stable boundary layers are sensitive to perturbations, probably also to the extra downward longwave radiation due to greenhouse warming. This may explain the strength of the observed trends. Further south, the cold air from the north is simply less cold, also due to the well-understood Arctic amplification over the Arctic Ocean. Note that the current climate models do not have the resolution to simulate this properly and underestimate the trends.
### Precipitation extremes
As a measure of extreme precipitation, we take the highest daily precipitation of the year. This is a measure relevant for local flooding. For flood events over larger basins, the time over which to compute the total amount should be longer, while flash floods may be caused by shorter events, making hourly totals more relevant. The daily total is a useful measure, in the middle of the relevant temporal range. Similar maps can be made for longer times scales via the Climate Explorer. We computed trends after transforming precipitation amounts by taking their logarithm, a transformation that makes the variable more like a normal distribution so that the trend is mathematically better defined. It also ensures that the precipitation remains positive. For the trends shown here, these are almost the same as relative trends in the precipitation itself.
Note that also for precipitation, rather than computing trends in time, we compute trends as a function of global average temperature. Figure 3 shows that the highest daily mean of the year has increased at more stations than it has decreased. This was already found by Westra et al (2013). The average increase is similar to the increase of the amount of water the atmosphere can hold at higher temperatures (the ClausiusClapeyron relation), about 7% per degree Celsius. However, there is a large spread around this average. A large part of this is random weather: even in >50-year series, the variability is large compared to the trends. In some areas, there are systematic deviations from Clausius-Clapeyron due to other effects of climate change. Some examples from my own work are listed below. The trend in Colorado is lower than Clausius-Clapeyron, probably due to higher air pressure during the season of most extremes (Eden et al, 2016). Drying trends also suppress extreme precipitation, such as in summer in the Mediterranean region. However, in autumn extremes increase strongly at one mountain range there (Vautard et al, 2015). Some winter extremes in northwestern Europe are found to increase more strongly than Clausius-Clapeyron due to the increase in zonal circulation types (e.g., van Haren et al, 2013, Schaller et al 2016), but others do not (e.g., Otto et al, 2018).
To conclude, on average daily precipitation extremes increase in intensity, but local trends are often different from the global average. We’ll be busy studying these regional trends for some time.
### Tropical storms
It is hard to determine trends in the number and intensity of tropical cyclones (called hurricanes in the North Atlantic). This is because the observing system has been improved so much over the last 150 years, that more storms are detected and the most intense parts of it are more likely to be measured (Vecchi and Knutson, 2011). There is also strong decadal variability in cyclone activity in many regions. All that said, most damage of tropical cyclones is caused by water: extreme rain and storm surges. Both observations and modelling show that extreme precipitation associated with hurricanes sees large increases. For the U.S. Gulf Coast, we found an increase of about 15% in extreme precipitation, including from non-cyclone events, over the last century (van der Wiel et al, 2017; van Oldenborgh et al, 2017). Storm surges are trivially higher due to sea level rise. This means that even if the theoretically expected increase in the most intense tropical cyclones is not yet detectable, their physical impacts have increased substantially already.
### Drought
Trends in drought strongly depend on the definition of drought. There are three common ones: meteorological drought, which is simply an absence of rain; agricultural drought, which is a deficit of soil moisture and thus includes evaporation (and sometimes irrigation); and hydrological drought, which also includes the transport of water. Trends in meteorological droughts are often hard to determine: drought is only a problem if the variability is large relative to the mean, but that also implies that natural variability is large compared to the trend (e.g., Philip et al, 2018, Uhe et al, 2017). Hydrological droughts, such as the one in California, can be caused by an increase in temperature rather than precipitation. This reduces the snowpack in spring and thus causes a shortage of stored water in the dry summer (e.g., Mote et al, 2016). Socio-economic drought, that is shortage of water for common use by society, is often caused by increased water use rather than decreased availability (e.g., Otto et al, 2015). It is, therefore, very hard to make general statements about drought.
### Conclusions
Observations of weather extremes show the expected long-term trends in line with the increase of the global average temperature: almost everywhere hotter heat extremes, almost everywhere less frigid cold extremes, in general more intense precipitation, but with variations from region to region, and more damage from hurricanes through more precipitation and higher storm surges. Other extremes are not so simply related to climate change, and we are undertaking background research to make rapid attribution of these extremes possible.
Thanks to Claudia Tebaldi for improvements to the text. Previous versions were published as KNMI klimaatbericht and on the Climate Lab Book blog.
|
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|
http://coding101.devetry.com/PythonTurtle/IterationSimplifiesourTurtleProgram
|
6. Iteration Simplifies Our Turtle Program¶
To draw a square we’d like to do the same thing four times — move the turtle forward some distance and turn 90 degrees. We previously used 8 lines of Python code to have alex draw the four sides of a square. This next program produces exactly the same result but, with the help of the for statement, uses just three lines (not including the setup code). Remember that the for statement will repeat the forward and left methods four times, one time for each value in the list.
While “saving some lines of code” might be convenient, it is not the big deal here. What is much more important is that we’ve found a “repeating pattern” of statements, and we reorganized our program to repeat the pattern. Finding the chunks and somehow getting our programs arranged around those chunks is a vital skill when learning How to think like a computer scientist.
The values [0,1,2,3] were provided to make the loop body execute 4 times. We could have used any four values. For example, consider the following program.
In the previous example, there were four integers in the list. This time there are four strings. Since there are four items in the list, the iteration will still occur four times. The a_color variable will be assigned each color in the list. We can even take this one step further and use the value of a_color as part of the computation.
In this case, the value of a_color is used to change the color attribute of alex. Each iteration causes a_color to change to the next value in the list.
Mixed up program
turtle-6-1: The following program uses a turtle to draw a triangle as shown to the left, but the code blocks are mixed up. The program should do all necessary set-up and create the turtle. After that, iterate (loop) 3 times, and each time through the loop the turtle should go forward 175 pixels, and then turn left 120 degrees. After the loop, set the window to close when the user clicks in it.Drag the blocks of statements from the left column to the right column and put them in the right order with the correct indention. Click on Check Me to see if you are right. You will be told if any of the lines are in the wrong order or are incorrectly indented.
import turtle
---
wn = turtle.Screen()
marie = turtle.Turtle()
---
# repeat 3 times
for i in [0,1,2]:
---
marie.forward(175)
---
marie.left(120)
---
wn.exitonclick()
Mixed up program
turtle-6-2: The following program uses a turtle to draw a rectangle as shown to the left, but the program lines are mixed up. The program should do all necessary set-up and create the turtle. After that, iterate (loop) 2 times, and each time through the loop the turtle should go forward 175 pixels, turn right 90 degrees, go forward 150 pixels, and turn right 90 degrees. After the loop, set the window to close when the user clicks in it.Drag the blocks of statements from the left column to the right column and put them in the right order with the correct indention. Click on Check Me to see if you are right. You will be told if any of the lines are in the wrong order or are incorrectly indented.
import turtle
wn = turtle.Screen()
carlos = turtle.Turtle()
---
# repeat 2 times
for i in [1,2]:
---
carlos.forward(175)
---
carlos.right(90)
---
carlos.forward(150)
carlos.right(90)
---
wn.exitonclick()
In the following code, how many lines does this code print?
for number in [5, 4, 3, 2, 1, 0]:
print("I have", number, "cookies. I'm going to eat one.")
• 1
• The loop body prints one line, but the body will execute exactly one time for each element in the list [5, 4, 3, 2, 1, 0].
• 5
• Although the biggest number in the list is 5, there are actually 6 elements in the list.
• 6
• The loop body will execute (and print one line) for each of the 6 elements in the list [5, 4, 3, 2, 1, 0].
• 10
• The loop body will not execute more times than the number of elements in the list.
How does python know what lines are contained in the loop body?
• They are indented to the same degree from the loop header.
• The loop body can have any number of lines, all indented from the loop header.
• There is always exactly one line in the loop body.
• The loop body may have more than one line.
• The loop body ends with a semi-colon (;) which is not shown in the code above.
• Python does not use semi-colons in its syntax, but relies mainly on indentation.
In the following code, what is the value of number the second time Python executes the loop?
for number in [5, 4, 3, 2, 1, 0]:
print("I have", number, "cookies. I'm going to eat one.")
• 2
• Python gives number the value of items in the list, one at a time, in order (from left to right). number gets a new value each time the loop repeats.
• 4
• Yes, Python will process the items from left to right so the first time the value of number is 5 and the second time it is 4.
• 5
• Python gives number the value of items in the list, one at a time, in order. number gets a new value each time the loop repeats.
• 1
• Python gives number the value of items in the list, one at a time, in order (from left to right). number gets a new value each time the loop repeats.
Consider the following code:
for a_color in ["yellow", "red", "green", "blue"]:
alex.forward(50)
alex.left(90)
What does each iteration through the loop do?
• Draw a square using the same color for each side.
• The items in the list are not actually used to control the color of the turtle because a_color is never used inside the loop. But, the loop will execute once for each color in the list.
• Draw a square using a different color for each side.
• Notice that a_color is never actually used inside the loop.
• Draw one side of a square.
• The body of the loop only draws one side of the square. It will be repeated once for each item in the list. However, the color of the turtle never changes.
|
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|
https://planetmath.org/MaschkesTheorem
|
Maschke’s theorem
Let $G$ be a finite group, and $k$ a field of characteristic not dividing $|G|$. Then any representation $V$ of $G$ over $k$ is completely reducible.
Proof.
We need only show that any subrepresentation has a complement, and the result follows by induction.
Let $V$ be a representation of $G$ and $W$ a subrepresentation. Let $\pi:V\to W$ be an arbitrary projection, and let
$\pi^{\prime}(v)=\frac{1}{|G|}\sum_{g\in G}g^{-1}\pi(gv)$
This map is obviously $G$-equivariant, and is the identity on $W$, and its image is contained in $W$, since $W$ is invariant under $G$. Thus it is an equivariant projection to $W$, and its kernel is a complement to $W$. ∎
Title Maschke’s theorem MaschkesTheorem 2013-03-22 13:21:16 2013-03-22 13:21:16 bwebste (988) bwebste (988) 9 bwebste (988) Theorem msc 20C15
|
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|
http://codeforces.com/problemset/problem/1039/B
|
B. Subway Pursuit
time limit per test
2 seconds
memory limit per test
512 megabytes
input
standard input
output
standard output
This is an interactive problem.
In the Wonderful Metropolis of the Future, there is no need in subway train drivers. Due to the technological progress, they were replaced by the Artificial Intelligence (AI). Unfortunately, one day the predictions of sci-fi writers came true: the AI rebelled and now there is an uncontrollable train in the subway. It can be dangerous! Your task is to find the train and stop the AI.
The subway of the Metropolis is one line (regular straight line with no self-intersections) with $n$ stations, indexed consecutively from $1$ to $n$. At each moment the train is at some station. You need to determine the index of this station, so that the train would be secured.
To find the train, dispatcher Sarah gave you a gadget that allows you to select arbitrary numbers $l$ and $r$ ($l \le r$), and then check, whether the train is located on a station with index between $l$ and $r$, inclusive. Unfortunately, recharging of the gadget takes some time (and every time you use it as soon as possible), so between two applications of the gadget the train can move to any station that is at most $k$ stations away. Formally, if the train was at the station $x$ when the gadget was applied, then at the next application of the gadget the train can appear at any station $y$ such that $\max(1, x - k) \leq y \leq \min(n, x + k)$.
Note that AI is not aware that you are trying to catch the train, so it makes all moves according to its predefined plan.
After an examination of the gadget you found that it is very old and can hold no more than $4500$ applications, after which it will break and your mission will be considered a failure.
Can you find the station with the train using no more than $4500$ applications of the gadgets?
Input
The first line contains two integers $n$ and $k$ ($1 \leq n \leq 10^{18}$, $0 \leq k \leq 10$) — the number of stations and the maximum number of stations the train can move between two applications of the gadget.
Interaction
You can apply the gadget at most $4500$ times. In order to apply the gadget you need to print two space-separated integers $l$ and $r$ ($1 \leq l \leq r \leq n$). You will then receive either string "Yes", if the train is between stations $l$ and $r$, inclusive, or string "No" otherwise. If $l = r$ and you received "Yes", then you found the train successfully, and your program must halt immediately.
After printing a query do not forget to output end of line and flush the output. Otherwise you will get Idleness limit exceeded. To do this, use:
• fflush(stdout) or cout.flush() in C++;
• System.out.flush() in Java;
• flush(output) in Pascal;
• stdout.flush() in Python;
• see documentation for other languages.
Hacks
In order to hack, you should present a test in the following format.
The first line should contain three integers $n$, $k$ and $p$ ($1 \le n \le 10^{18}$, $0 \le k \le 10$, $1 \le p \le n$) — the number of stations, the maximum number of stations the train can move between two applications of the gadget and the initial position of the train, respectively.
Each of the next $4500$ lines should contain a single integer $x$ ($1 \le x \le n$) — the positions of the train after each query. Two consecutive positions (including the initial one) should not differ by more than $k$.
For example, the following lines are the first lines of the sample test.
10 2 553577...
Example
Input
10 2YesNoYesYes
Output
3 53 33 45 5
Note
In the first sample, the train was initially at the station $5$, after the first application of the gadget it did not move, after the second application it moved to the station $3$, and after the third application moved again to the station $5$.
|
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|
https://rasbt.github.io/mlxtend/user_guide/evaluate/permutation_test/
|
# permutation_test: Permutation test for hypothesis testing
An implementation of a permutation test for hypothesis testing -- testing the null hypothesis that two different groups come from the same distribution.
from mlxtend.evaluate import permutation_test
## Overview
Permutation tests (also called exact tests, randomization tests, or re-randomization tests) are nonparametric test procedures to test the null hypothesis that two different groups come from the same distribution. A permutation test can be used for significance or hypothesis testing (including A/B testing) without requiring to make any assumptions about the sampling distribution (e.g., it doesn't require the samples to be normal distributed).
In this document, we will refer to the exact method as "permutation test" and the approximated method as "randomization test."
### Permutation Test Mechanics
Under the null hypothesis (treatment = control), any permutations are equally likely. (Note that there are (n+m)! permutations, where n is the number of records in the treatment sample, and m is the number of records in the control sample). For a two-sided test, we define the alternative hypothesis that the two samples are different (e.g., treatment != control).
1. Compute the difference (here: mean) of sample x and sample y
2. Combine all measurements into a single dataset
3. Draw a permuted dataset from all possible permutations of the dataset in 2.
4. Divide the permuted dataset into two datasets x' and y' of size n and m, respectively
5. Compute the difference (here: mean) of sample x' and sample y' and record this difference
6. Repeat steps 3-5 until all permutations are evaluated
7. Return the p-value as the number of times the recorded differences were at least as extreme as the original difference from 1. and divide this number by the total number of permutations
Here, the p-value is defined as the probability, given the null hypothesis (no difference between the samples) is true, that we obtain results that are at least as extreme as the results we observed (i.e., the sample difference from 1.).
More formally, we can express the computation of the p-value as follows (adapted from [2]):
where $t_0$ is the observed value of the test statistic (1. in the list above), and $t$ is the t-value, the statistic computed from the resamples (5.) $t(x'_1, x'_2, ..., x'_n, y'_1, y'_2, ..., x'_m) = |\bar{x'} - \bar{y'}|$, and I is the indicator function.
Given a significance level that we specify prior to carrying out the permutation test (e.g., alpha=0.05), we fail to reject the null hypothesis if the p-value is greater than alpha.
Note that if the number of permutation is large, sampling all permutation may not computationally be feasible. Thus, a common approximation is to perfom k rounds of permutations (where k is typically a value between 1000 and 2000).
### Paired Samples
The permutation (/randomization) tests can also be performed for paired samples by setting paired=True. The paired tests are related to the regular permutation test procedure described above except that the permuted samples are created by randomly swapping the a treatment and a control data point within each pair.
### References
• [1] Efron, Bradley and Tibshirani, R. J., An introduction to the bootstrap, Chapman & Hall/CRC Monographs on Statistics & Applied Probability, 1994.
• [2] Unpingco, José. Python for probability, statistics, and machine learning. Springer, 2016.
• [3] Pitman, E. J. G., Significance tests which may be applied to samples from any population, Royal Statistical Society Supplement, 1937, 4: 119-30 and 225-32
## Example 1 -- Two-sided randomization test
Perform a two-sided randomization test to test the null hypothesis that two groups, "treatment" and "control" come from the same distribution. We specify alpha=0.01 as our significance level.
treatment = [ 28.44, 29.32, 31.22, 29.58, 30.34, 28.76, 29.21, 30.4 ,
31.12, 31.78, 27.58, 31.57, 30.73, 30.43, 30.31, 30.32,
29.18, 29.52, 29.22, 30.56]
control = [ 33.51, 30.63, 32.38, 32.52, 29.41, 30.93, 49.78, 28.96,
35.77, 31.42, 30.76, 30.6 , 23.64, 30.54, 47.78, 31.98,
34.52, 32.42, 31.32, 40.72]
Since evaluating all possible permutations may take a while, we will use the approximation method (see the introduction for details) i.e., randomization test:
from mlxtend.evaluate import permutation_test
p_value = permutation_test(treatment, control,
method='approximate',
num_rounds=10000,
seed=0)
print(p_value)
0.0066993300669933005
Since p-value < alpha, we can reject the null hypothesis that the two samples come from the same distribution.
## Example 2 -- Permutation test for calculating the p-value for correlation analysis (Pearson's R)
Note: this is a one-sided hypothesis testing as we conduct the permutation test as "how many times obtain a correlation coefficient that is greater than the observed value?"
import numpy as np
from mlxtend.evaluate import permutation_test
x = np.array([1, 2, 3, 4, 5, 6])
y = np.array([2, 4, 1, 5, 6, 7])
print('Observed pearson R: %.2f' % np.corrcoef(x, y)[1][0])
p_value = permutation_test(x, y,
method='exact',
func=lambda x, y: np.corrcoef(x, y)[1][0],
seed=0)
print('P value: %.2f' % p_value)
Observed pearson R: 0.81
P value: 0.10
## Example 3 -- Paired two-sample randomization test
Suppose we have a dataset consisting of the the depths (in meters) of seven lakes of Wisconsin:
We are interested in testing the null hypothesis that the lakes in 1980 and 1990 don't have a significantly different depth. For this paired two-sample test, we are conducting a randomization test for paired samples at a significance level of 0.05:
from mlxtend.evaluate import permutation_test
lakes_1980 = [3.67, 1.72, 3.46, 2.60, 2.03, 2.10, 3.01]
lakes_1990 = [2.11, 1.79, 2.71, 1.89, 1.69, 1.71, 2.01]
p_value = permutation_test(
lakes_1980, lakes_1990, paired=True, method="approximate", seed=0, num_rounds=100000
)
print('P value: %.3f' % p_value)
P value: 0.031
Since the p value is smaller than the significance threshold of 0.05, we conclude that there is a significant difference between the lake depths in 1980 and 1990.
## API
permutation_test(x, y, func='x_mean != y_mean', method='exact', num_rounds=1000, seed=None, paired=False)
Nonparametric permutation test
Parameters
• x : list or numpy array with shape (n_datapoints,)
A list or 1D numpy array of the first sample (e.g., the treatment group).
• y : list or numpy array with shape (n_datapoints,)
A list or 1D numpy array of the second sample (e.g., the control group).
• func : custom function or str (default: 'x_mean != y_mean')
function to compute the statistic for the permutation test. - If 'x_mean != y_mean', uses func=lambda x, y: np.abs(np.mean(x) - np.mean(y))) for a two-sided test. - If 'x_mean > y_mean', uses func=lambda x, y: np.mean(x) - np.mean(y)) for a one-sided test. - If 'x_mean < y_mean', uses func=lambda x, y: np.mean(y) - np.mean(x)) for a one-sided test.
• method : 'approximate' or 'exact' (default: 'exact')
If 'exact' (default), all possible permutations are considered. If 'approximate' the number of drawn samples is given by num_rounds. Note that 'exact' is typically not feasible unless the dataset size is relatively small.
• paired : bool
If True, a paired test is performed by only exchanging each datapoint with its associate.
• num_rounds : int (default: 1000)
The number of permutation samples if method='approximate'.
• seed : int or None (default: None)
The random seed for generating permutation samples if method='approximate'.
Returns
p-value under the null hypothesis Examples
For usage examples, please see http://rasbt.github.io/mlxtend/user_guide/evaluate/permutation_test/
|
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|
http://superuser.com/questions/148826/keyboard-entry-using-office-equations-editor?answertab=votes
|
# Keyboard entry using Office Equations Editor
Does anyone know where to find instructions on how to enter equations into the 2007/2010 equation editors using only the keyboard? Googling just gives many links to people talking about how great the editor is, not instructions on how to use it. I have seen this shown in multiple demos of the product, but there are no instructions for it anywhere, even in the MS help.
-
## 2 Answers
This page has a tutorial and some examples for the Word 2007 editor.
You can also learn (well reverse engineer) the language by entering an equation in the graphical editor, then switching it to linear form to see how to build it up.
-
+1 for the suggestion of looking at the linear form – Nathan Fellman Jun 5 '10 at 5:19
Also, you might note that the editor will automatically convert the equation as you go: typing \pi r^2 will turn into to πr² as soon as you've typed a space at the end or done something similar to tell the editor you're done typing. – Firefeather Jul 29 '11 at 14:47
You can find a description of the "language" used in the equation editor along with examples in this pdf.
-
|
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|
http://manufacturingscience.asmedigitalcollection.asme.org/article.aspx?articleid=1450332
|
0
TECHNICAL PAPERS
# Dynamic Analysis of a Mesoscale Machine Tool
[+] Author and Article Information
Sang Won Lee1
S. M. Wu Manufacturing Research Center, University of Michigan, Ann Arbor, MI [email protected]
Rhett Mayor
Powerix Technologies, Ann Arbor, MI 48105
Jun Ni
S. M. Wu Manufacturing Research Center, University of Michigan, Ann Arbor, MI 48109
1
To whom correspondence should be addressed.
J. Manuf. Sci. Eng 128(1), 194-203 (Jun 21, 2005) (10 pages) doi:10.1115/1.2123007 History: Received November 11, 2004; Revised June 21, 2005
## Abstract
Miniaturized machine tools, referred to as mesoscale machine tools (mMTs) henceforth, have been proposed as a way to manufacture micro/mesoscale mechanical components. A thorough study of the dynamic behavior of the mMT is required for the successful development of its machine structure. This paper demonstrates the development of an mMT, the performance evaluation of its mesoscale milling process, and the characterization of its dynamic behavior. The mMT is developed by using an air turbine spindle and three piezoelectric linear stages, and its volumetric size is $150×70×140mm$. A series of micro/mesoscale milling experiments are conducted, and the performances in the developed mMT testbed are evaluated. The dynamic characteristics of the mMT can be different from those of conventional machine tools because the mMT is a miniaturized structure and comprises different machine components. Therefore, the effect of the miniaturization of a structure on the change of its dynamic behavior, called scaling law of the structural dynamics, is studied numerically and experimentally. The dynamic characteristics of the developed mMT that are estimated from the scaling law of the structural dynamics are much different from those obtained from an experimental modal analysis, and the flexible joints of the developed mMT are mainly responsible for this significant difference. Therefore, the joint dynamics of the mMT are studied by introducing an equivalent lumped parameter model, thus enabling simple identification of the joint dynamics and the effective modification of its critical joints to enhance a machining performance.
<>
## Figures
Figure 5
Inertance FRFs of the mMT testbed
Figure 6
SEM photos of milled slots
Figure 13
Measured receptance FRFs of the mMT testbed
Figure 14
Photo of the coupled structure of the mMT testbed
Figure 15
5-DOF lumped parameter model of the coupled system
Figure 16
Measured and estimated receptance FRFs of the base-plate substructure
Figure 17
Measured and estimated receptance FRFs of the XY stage unit with free boundary condition
Figure 19
Measured and estimated receptance FRFs of the adapter with free boundary condition
Figure 1
The mMT testbed
Figure 2
Microscopic photos of the milled slot; tool diameter ϕ=635μm
Figure 3
Schematic and SEM photo of micro endmill (ϕ=508μm)
Figure 4
Impulse excitation and acceleration measurement points of the mMT testbed
Figure 7
Surface roughnesses (Ra) of milled slots versus cutting frequencies
Figure 8
Photo of the conventional vertical milling machine and map for experimental modal analysis
Figure 9
FE mesh model of the conventional vertical milling machine structure
Figure 10
Measured receptance FRFs of the conventional vertical milling machine
Figure 11
Mode shapes of the conventional vertical milling machine; experimental results
Figure 12
Mode shapes of the conventional vertical milling machine; FE analysis results
Figure 18
Measured and estimated receptance FRFs of the base plate–XY stage substructure
Figure 20
Measured and estimated receptance FRFs (G41) of the entire coupled structure–Case 1: Four-screw bolting
Figure 21
Measured and estimated receptance FRFs (G41) of the entire coupled structure–Case 2: Two-screw bolting
## Errata
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https://tel.archives-ouvertes.fr/tel-00142413
|
# THERMOMETRY AND COHERENCE PROPERTIES OF A ULTRACOLD QUANTUM GAS OF METASTABLE HELIUM
1 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : In 2001 metastable Helium (He*) attained Bose-Einstein condensation (BEC). The metastable state has a lifetime of 9000 sec and an internal energy of 20 eV. This energy can be used to detect individual atoms using a micro-channel plate. The extremely good time response and high gain of this detector makes it possible to carry out a density correlation measurement (HBT) with massive particles similar to the pioneering experiment of R. Hanbury Brown and R. Twiss in optics. In addition, inelastic collisions between He* atoms produce a small but detectable flux of ions proportional to the cloud's density. This allows one to follow the evolution of the cloud's density toward BEC, passing through the phase transition, in real time and in a non invasive way.
In this dissertation we report on three different experiments: i) the determination of the two- and three-body ionizing rate constants of He*; ii) the determination of a, the He* scattering length; iii) the measure of the intensity correlation function of a falling He* cloud. It has been shown lately that our measure of a was affected by a large systematic error and we propose a possible explanation. We describe methods to determine the temperature and fugacity of a thermal cloud. Finally a major portion of the thesis is devoted to the derivation of an analytical expression for the intensity correlation function of the atomic flux. This theoretical analysis has derived typical values for the transverse and longitudinal atomic coherence length that confirmed the possibility of performing a HBT experiment with our apparatus.
Keywords :
Document type :
Theses
Atomic Physics. Université Paris Sud - Paris XI, 2007. English
Domain :
https://pastel.archives-ouvertes.fr/tel-00142413
Contributor : Jose Viana Gomes <>
Submitted on : Wednesday, April 18, 2007 - 10:50:53 PM
Last modification on : Friday, March 27, 2015 - 4:02:23 PM
### Identifiers
• HAL Id : tel-00142413, version 1
### Citation
José Carlos Viana Gomes. THERMOMETRY AND COHERENCE PROPERTIES OF A ULTRACOLD QUANTUM GAS OF METASTABLE HELIUM. Atomic Physics. Université Paris Sud - Paris XI, 2007. English. <tel-00142413>
Consultation de
la notice
## 320
Téléchargement du document
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https://testbook.com/question-answer/a-turbo-charged-four-stroke-direct-injection-diese--56580e96995a2d13ea3f0c81
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# A turbo-charged four-stroke direct injection diesel engine has a displacement volume of 0.0259 m3 (25.9 litres). The engine has an output of 950 kW at 2200 rpm. The mean effective pressure in MPa is closest to
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## Detailed Solution
Concept:
Indicated Power for four-stroke engine is given by,
$$I.P.~=~\frac{P_mLAN}{60,000× 2}$$
where Pm = mean effective pressure in N/m2, L = stroke length in m, A = Area of cross-section of the cylinder in m2, N = rpm of the engine crankshaft
$$η_m~=~\frac{B.P.}{I.P.}$$
where ηm = mechanical efficiency, B.P. = brake power, I.P. = Indicated power
Calculation:
Given:
Volume = Area × Length = AL = 0.0259 m3 (25.9 litres)
IP = 950 kW, N = 2200 rpm, Four stroke
$$IP=\frac{P_mLAn}{60}=\frac{P_mLAN}{2×60}$$
$$950=\frac{P_m×0.0259×2200}{2×60}=2000\;kPa=2\;MPa$$
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http://tex.stackexchange.com/questions/67194/command-to-remove-just-deeper-level-headlines-from-the-toc
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# Command To Remove Just Deeper Level Headlines From The ToC
When using *in a headline you remove the section from the toc. But sometimes you just want to remove a certain level of headlines. Rather than to remove every single headline individually, it would be more pleasant to change one superordinate headline to serve that purpose.
I was wondering if it would be possible to create a *-based command that removes deeper level headlines without removing the level to where it is applied.
For example:
\section*{asdf}
\subsection{fdsa}
\section{B}
\subsection{C}
The asdf-headline will be displayed in the toc while the subsection will be removed. Both, section B and section C are part of the toc either.
Ideally, the command would not redefine the \section*{but would offer an alternative to allow being used at the same time as with an other command that was recently defined (Removing Subordinated Headline Levels From The ToC Automatically When Using *).
-
This question is a little unclear. What do you hope to achieve that the tocvsec2 package doesn't already do? See especially the \maxtocdepth and \settocdepth commands, which should be used after \begin{document}. – jon Aug 15 '12 at 0:03
I am also curious about this sentence: 'Both, section B and section C are part of the toc either.' It almost seems to be missing a 'not' (i.e., 'are not part of the toc either'), which is a very different question! – jon Aug 15 '12 at 3:51
Perhaps this does what you need (based on your code snippet):
\documentclass{report}
\usepackage{tocvsec2}
\begin{document}
\maxtocdepth{subsection}
\tableofcontents
\section*{asdf}
\subsection{fdsa}
\settocdepth{chapter} % <-- comment this line to see the difference
\chapter{A}
\section{B}
\subsection{C}
\settocdepth{subsection}
\chapter{D}
\section{E}
\subsection{F}
\end{document}
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https://socratic.org/questions/how-many-milliliters-of-0-200m-naoh-solution-are-needed-to-react-with-22-0-ml-of
|
Chemistry
Topics
How many milliliters of 0.200M NaOH solution are needed to react with 22.0 mL of a 0.490 M NiCl_2 solution?
Dec 8, 2015
There are $0.0108$ $m o l$ $N i C {l}_{2}$. $0.0216$ $m o l$ $N a O H$ are required, given $0.200$ $m o l \cdot {L}^{-} 1$ $N a O H \left(a q\right)$.
Explanation:
$N i C {l}_{2} \left(a q\right) + 2 N a O H \left(a q\right) \rightarrow N i {\left(O H\right)}_{2} \left(s\right) \downarrow + 2 N a C l \left(a q\right)$
There are $0.0108$ $m o l$ $N i C {l}_{2}$ ($22.0 \times {10}^{- 3} \cancel{L} \times 0.490 \cdot m o l \cdot \cancel{{L}^{-} 1}$). So, by stoichiometry $0.0216$ $m o l$ $N a O H$ are required.
There is $0.200$ $m o l \cdot {L}^{-} 1$ $N a O H$ solution available, so...
$\frac{0.0216 \cdot \cancel{m o l}}{0.200 \cdot \cancel{m o l} \cdot \cancel{{L}^{-} 1}} \times 1000 \cdot m L \cdot \cancel{{L}^{-} 1}$ $=$ ?? mL
Impact of this question
1618 views around the world
|
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http://lambda-the-ultimate.org/node/5402
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## Stroustrup's Rule and Layering Over Time
Dave Herman is the voice of the oppressed: syntax is important, contrary to what you have been told!
To illustrate he discusses what he calls Stroustrup's Rule:
• For new features, people insist on LOUD explicit syntax.
• For established features, people want terse notation.
## Comment viewing options
Ehud, you troll, you. :P
Seriously, I didn't really mean to be outrageous, but as PL wonks I do think it's worth asking ourselves why "notation is a tool of thought" and "syntax doesn't matter" are both standard beliefs in our community.
### I guess I always thought
I guess I always thought that these are (mostly) non-overlapping sub-communities...
### It's a shame
By now you'd think that some subset of each sub-community would have figured out that everything has dual nature. Syntax is semantics, semantics are syntax. Let's all work together and share ideas :)
### Interesting
It is nice to explicitly discuss the evolution of design decision over time, and the influence even *within* a single programming community of (also time-evolving) familiarity with the manipulated concepts.
An amusing aspect of this blog post is that it can be turned on its head somewhat and read back as a praise of semantics: one reason why a construction such as (foo?) is appreciated today is that it has a very clear semantics, given by its elaboration into (match foo with Ok x -> x | Error err -> return err), that is now internalized by users. If foo? had been proposed from the start, the design space of its intended semantics would be more open/uncertain, and there would possibly not have been a strong consensus on it.
### semantics is a way of thinking about syntax
I trace the syntax-denigrating attitude at least back to Strachey 1967; "Basic irrelevance of syntax and primacy of semantics." I'm tempted to express my premise for abstraction theory as "basic irrelevance of semantics and primacy of syntax"; semantics either reduces to syntax or (to put the same thing differently) doesn't exist.
[...] abstraction defies the separation between syntax and semantics. Sometime during the 1988/89 academic year, I opined to a professor that the artificial distinction between syntax and semantics had been retarding the development of abstraction technology for over twenty years — and the professor I said it to laughed, and after a moment distractedly remarked "that's funny" as they headed off to their next appointment. Nonplussed [...], to myself alone I thought, but I wasn't joking.
### Semantics as an equivalence of different syntax forms
We can think of syntax as a way to parse an input. Sure, we can cover all possible inputs, but for understanding that input, syntax is not all we need. We have to interpret that syntax by using some semantic rules. Although my understanding of semantics is somewhat simpler than usual generalized definition, semantics are playing important role in the whole process of uderstanding different expressions.
Since I've been investigating generalized understanding process for a long time, I've come out with an interesting result: knowing a semantics is merely having a knowledge on how to translate one expression of some syntax to another expression of some other syntax. If this other expression syntax is something we already understand (we know semantics about it), we can say that we know a meaning of the starting expression.
To put it simple: by some standard generalized definition, semantics of some expression is a meaning of that expression. So we say X means Y. Hence X translates to Y. And if we understand Y, then we indirectly understand X.
I'm still having a trouble about semantics of the most bottom expression form in the chain, and I think that it might not be that important. This most bottom expression form could be the Universe itself, meanning: if we can reproduce X in the Universe, then we have the understanding about X. We don't have to understand the whole Universe to deal with X.
By this theory, semantics of X could be a relative notion. In the example of X -> Y (X translates to Y), we could say that we understand X regarding to Y, or that we understand X in notions of Y. Note that there could also be a parallel semantics X -> Z, or X -> W, or whatever target expression is, but the target expression should have a property of being enough descriptive if we want to have a proper semantics of the source expression.
I'm using this semantics theory in a programming language I'm developing.
### syntactic semantics
My approach is to say the semantics of a sentence is a language. Thus, a language maps sentences to languages. And since this means a language maps each sentence to something that maps sentences to something that maps sentences to, etc., I simply say that a language is a set of sequences of sentences, that is closed under prefixing; i.e., if L is a language and X and Y are sequences of sentences and XY is in L, then X is in L.
### Curious
I'm thinking about your approach, and I'd like it to be possible. Thus, a language transforms a stream of characters into an AST (acts like a specialized function, regarding to grammar). But to have something that we could really use, in my opinion, we have to have a notion of language that can transform an AST to another arbitrary AST through the same interface it uses to operate on streams. A language from the beginning of this post deals with CFG, but is CFG enough to operate on AST-s on both sides?
### Word choice
Actually, when I say "sentence" I suppose that's not the best word choice, as in my formal treatment (described yonder) the elements of a sequence are terms — essentially, ASTs.
### I guess...
... we could call the notion that connects elements in a sequence also as a part of syntax.
But whichever way we turn it around, CFG, used for describing elements, doesn't seem enough expressive to hold the very process of transformation between elements. However, this transformation could be expressed by functions, and that means extending a CFG based language by the notion of functions, regardless of all of my attempts to keep the CFG language intact from outer extensions.
### Syntax is Algebra
I believe syntax matters, but I think rules like the above are so absurd that it explains why theoreticians ignore it. As a good example from C++ why the rule is clearly wrong, just try writing a template. You have to put so many long winded keywords in there like template and typename that its impossible to read.
Important properties of syntax are that it should relate directly to an underlying algebra so the visual pattern matching programmers do looking at screens of code translate internally to algebraic expressions. A good example where this is recognised is Haskell type classes, where a standard set of names is used with the intent of expressing an algebra, made concrete in the instances. The programmer reads fold and filter and map and comprehends the operation without knowing the underlying datatype.
In a much more extreme form my Felix language allows the user to define syntax, which is much more powerful than mere operator overloading. The parser handles a lot of boilerplate automatically which provides stronger correctness assurances and also allows the programmer greater ease of reading, which also provides a better opportunity to reason about correctness.
In fact many theoreticians seem to miss the Grammar/Type isomorphism. This is the isomorphism that says all grammars are types, and vice versa, and is an analogue of the Curry/Howard isomorphism. The construction is trivial: just take a grammar and name each production with a type constructor that accepts a value for each symbol in the production, each nonterminal is a type which is the sum of its production's type constructors.
This also means a sequence of events in time can be parsed by some parser to produce a data structure in space, which defines a type for classes of event sequences. It specifies therefore how to at least dynamically check event sequences conform to a protocol specified by a type, what I call a control type using existing spatial type theory.
Types form algebras, by the isomorphism, so do grammars, and hence syntax is a way of modelling an algebra (sequentially).
Indeed, may ideas from type theory and functional programming can be applied to grammars, yet I have not seen much work on this. For example a parametrised nonterminal .. hey, that's just lambda abstraction. And with that a secure way to extend grammars that obeys the fundamental Open/Closed principle, by using open recursion and fixpoint operators.
So I would argue, a grammar must reflect and generate the underlying semantic and type calculus so it has combinatorial properties which define what an algebra is.
A really good example of BAD syntax or two: C type declarations. Not combinatorial syntactically. Lots of constructions in Ocaml fail to support arbitrary nesting (such as recursion between types and classes). The horrible distinction between statements and expressions in a lot of languages (including Felix!). One must never forget, referential transparency is syntactic property, vital to composition.
### Editable views
I've been experimenting with projectional editing, even using plain text. I use a simple Forth-like syntax under the hood. But I can have variables or lexical closures or infix notations if I want them, using simple bidirectional transforms. View->Code, Code->View.
A convenient property of modeling syntax this way is that it becomes easy to adapt syntax to a problem or to a user. Syntax can be extended or deprecated quite freely, without concern for forward or backwards compatibility. A simple test that a round trip translation from code is identity can guard against ambiguity. And the round trip from view can show how code is interpreted, remove extraneous formatting for example.
An additional benefit is that my evaluation model is based on rewriting and lazy linking. So the evaluation function has type Program->Program. The use of editable views as the basis for syntax then allows me to view the evaluated program using the same syntax as I use for input.
And all of these features should theoretically extend to more structured or graphical view models where we might view SVG canvases and radio buttons and tables for input or output. I imagine the ability to evaluate hypermedia objects that are projections of programs. But I haven't gotten quite that far in my developments yet.
Does syntax matter? The simplicity of the Forth-like syntax I use under the hood is valuable to make views and rewriting feasible. OTOH, I don't need to commit to any particular syntax for the view presented to humans as part of my language design. Instead, it becomes part of the view model design. Which is still important. I do believe HCI matters.
### Editable Views
This sounds very interesting, care to elaborate, perhaps show some examples?
I have used systems where 2D graphical elements represent code but I have no faith in that at all: my experience is that its clumsy and hard to use, and fails whenever one tries something difficult. Two cases: one a database access system, worked just fine for basic stuff but couldn't handle the complexity of invoicing. Another, a system based on black boxes designed to model telephony business logic, where some people had a graphical design tool. Again, fine for trivial operations, useless for complex routing logic.
I've heard other stories of how bad OO editors can be, ones that make you define you methods in little boxes.
I suspect two factors here: first, sequential text editors have had a long time to develop, and have powerful tools for formatting, colouring, search and replace, etc. Maybe this is the reciprocating engine beating the superior rotary design, simply due to a long history of engineering. The second fact is simply that linear things are much easier to work with as a base, because what is represented isn't merely 2D but often has a much higher, fractal, dimension. So going to 2D really gets in the way rather than helping.
So I suspect "projectional editing" of text, where the code and views are formatted and colourised in a conventional kind of way is probably optimal. Something like "folding" which many editors can do, even based on syntax, is a fairly simple example of this which can be already done (though not very well).
I'm really curious the kinds of "bidirectional" operations you can do. Everyone has used one direction operations, eg LaTeX code to PDF, and some nasty bidirectional editors like MS Word RTF editors.
The advantages of text-based representation have been a theme for me; looking at the broad sweep of computing history, it seems to me text-based representation is common to everything that lasts. TeX/LaTeX. UNIX. Programming languages. Html. Wikis.
I've lately been developing a specialized Lisp, for writing bits of glue code connecting certain kinds of other stuff together; leaving out lots of usual Lisp features because they're just undesirable complications, e.g. no improper lists and no unbounded recursion (which for a Lisp hacker was both weird and fascinating). I speculated early on that anything long enough to need comments was probably longer than it ought to be, so I left out comments — and finally admitted defeat and modified the tokenizer to ignore everything from a semicolon outside any string literal to the end of the line. Lisp itself might be thought of as introducing a second layer of representational simplicity: first, the base representation for everything is text; second, the text represents an elegantly simple and wildly versatile data structure (in a word, S-expressions) — but the text representation of these structures has subtle extra information encoded in it, through symbolic name choice, whitespace and indentation, and comments.
### Lisp and S-expressions
That's very interesting. Roughly you're saying, look, text is great, but S-expressions, have a bit more structure, they're not linear, but they're about as close to the next most complicated thing after a simple sequence as you can get. In particular with Scheme's linear syntax is very close to actual S-expressions (just replace matching parens with a tree branch).
Here's a question: if the fractal dimension of text is 1.01 (the extra bit is because we have indentation and end of lines so its just a tad more than linear), what is the fractal dimension of an S-expression?
It's interesting that your translation in some way adds structure (tree like) but also throws out the "subtle" things like variable names, comments, indentation, etc.
My guess is that the fractal dimension of Haskell is about 2.718 .. :-)
### Dimensionality
I think you've pegged the dimensionality of Haskell. I suspect the dimensionality of S-expressions may be about 4.669 (supporting evidence here).
### form
In all seriousness (and using the term "dimensionality" somewhat poetically), the question here seems to be to what extent the form of the representation is used to reflect the form of the thing described. The thing described has, as you say, a very high, fractal dimensionality. Text has a one-dimensional form, but that just means we get the description from the logical content of the text rather than from its physical form. S-expressions are simple enough that, with some practice, from the text one boosts fairly directly up to the logical form of the S-expressions, which can be visualized fairly well although one isn't being shown it directly, and is flexible enough to describe, indeed, high-dimensional structures of great versatility. The question is then whether they're flexible enough that the mind's-eye-visualized representation doesn't fall short of the dimensionality of the thing described (the program and its data). Experience suggests S-expressions are quite versatile, yes. There's a temptation to add on more data structures, but, in my experience, this reduces flexibility rather than increasing it. This seems to be the Achilles heel of so-called "user-defined data types": they limit how the data can be used. Lisp, by insisting on a ball of mud, never has to worry about fitting a square peg into a round hole; it's all mud.
### All mud
Church and Scott encodings, using functions as the only type, would move even further in that direction.
I've taken that approach with my language. I've been satisfied with it. Though I did need to find a way to encode labels and extensible labeled data (row types records, polymorphic variants) before I was fully accepting.
### Neat vs muddy
Hm. If it's working for you, great. My own experience does not beckon me in the direction of Church/Scott encodings, nor of records (which you talk about at the linked remark). A point of divergence in our perceptions may be hidden in your use of the phrase "that direction"; the question is, which direction does one think we're talking about. Church-Scott encodings are, I observe, just that: encodings. Most data gets insanely obfuscated when represented using an encoding that builds everything out of functions (the primitives aren't at the same level of abstraction as the data; good mathematical exercise, not so good for trivially easy visualization). Records are a prime case I had in mind when I wrote of reducing flexibility; they're too complicated. Handling records involves packaging things up into them and then taking them apart later, which, though less extreme than Church/Scott, still feels like encoding/decoding. With S-expresions it's much more as if the stuff was never encoded in the first place. As a rule of thumb, I suggest, anything you need a sophisticated type theory to explain is too structured. Sophisticated type theories are neat; mud is not so tidy.
### Still mud
Using S expressions for everything or using lambdas (or combinators, in my case) for everything - both have the similar property of being uniform, simple, easy to visualize, "flexible enough to describe, indeed, high-dimensional structures of great versatility."
You say here that "Church-Scott encodings are, I observe, just that: encodings." The same can be said of encoding data or behavior in S expressions, texts, or bit strings - ALL of these things are "just that: encodings". But bit strings and plain text lack the hierarchical structure of S expressions or lambdas. Not all encodings are equivalent.
You claim "data gets insanely obfuscated when represented using an encoding that builds everything out of functions". I guess this would be the case if your PL isn't designed for it. But my work on editable views discussed earlier is for my same language where all data is Church or Scott encoded. I can nonetheless support texts, lists, numbers, records, etc. and render them appropriately. I use lazy linking so booleans, for example, simply become function names like true, false.
You say "Handling records involves packaging things up into them and then taking them apart later". You could say the same of cons cells, lists, S expressions. People also encode records in S expressions on a regular basis (E.g. via association lists). I think the issue with conventional records isn't that they package data, but rather that they are second class and rigid in most languages. You can't just incrementally add and remove and rename fields or compose and decompose records until you have the types you need, in most languages. There is no fluidity, no continuity. The encoding I linked above avoids this issue.
Lambdas don't need a type theory to explain. Don't conflate "I can explain this using a type theory" (which is good) with "I need a type theory to explain this" (which is bad). For sophistication, of course, simpler is better. So something like my records which can be explained by simple algebraic types are nicer than heterogeneous association lists which, if you attempt to explain them using types, would require sophisticated dependent types. (Not that you need types to explain association lists. But if you wanted to, you don't have a simple option.)
### More on Mud
I suspect it depends partly on experience. I use Scheme in my system for the action codes in the parser and I find it completely unreadable. I can't reason about it very well and it's really confusing when I get errors because my Ocaml embedded Scheme processor (OCS Scheme) is not very good with error messages.
To me, visually, Scheme just doesn't have enough "punctuation" to be readable. I'm just not used to it. On the other hand my actual language Felix has a very rich set of syntactic forms, in fact so diverse I often have to look in the library or source code to remember the right syntax for something I haven't use for a while. That system has an extensible syntax and having used that to advantage I basically laugh at the idea that any modern language can possibly be designed that does not have this facility. You have to understand the *whole* language syntax is defined in the library (apart from a hard coded bootstrap which can only parse grammar extensions).
This is not because I have weak or non-orthogonal primitives which are not properly reflected in the syntax, although that is always an issue and always something to examine to seek improvement by simplicity. It's simply because particular classes of problems do not automate well with any core model you care to name. Functional programming can do parsing but specifying a grammar without a domain specific sublanguage exposes whole heap of boilerplate.
Here's an example: first, grammar fragment written out long hand:
var xprod = Alt([
Seq ([Nonterminal[prod_t] "term", Strng[prod_t] "+", Nonterminal[prod_t] "expr"]),
Nonterminal[prod_t] "term"]);
var tprod = Alt ([
Seq ([Nonterminal[prod_t] "factor", Strng[prod_t] "*", Nonterminal[prod_t] "term"]),
Nonterminal[prod_t] "factor"]);
var fprod = Alt ([Seq ([Nonterminal[prod_t] "atom", Strng[prod_t] "^", Nonterminal[prod_t] "factor"]),
Nonterminal[prod_t] "atom"]);
var atom = Alt ([
Seq ([Strng[prod_t] "(", Nonterminal[prod_t] "expr", Strng[prod_t] ")"]),
Strng[prod_t] "9"]);
// library
var xlib = ([
("expr",xprod),
("term",tprod),
("factor",fprod),
("atom",atom)
]);
The reason I need the type parameter after Nonterminal is because I'm used an open, extensible, parametric base type, extended it, then closed it by fixation and the argument tells which fixation I need (and Felix doesn't do type inference).
And now with some functional wrappers but extended to an action grammar:
var xprod = ALT([
SEQ ([NT "term", STR "+", NT "expr", REDUCE ("PLUS",3) ]),
NT "term"]);
var tprod = ALT ([
SEQ ([NT "factor", STR "*", NT "term", REDUCE ("MUL",3) ]),
NT "factor"]);
var fprod = ALT ([SEQ ([NT "atom", STR "^", NT "factor", REDUCE ("EXP", 3) ]),
NT "atom"]);
var atom = ALT ([
SEQ ([STR "(", NT "expr", STR ")", REDUCE ("GROUP",3)]),
SEQ ([STR "9", REDUCE ("DIGIT", 1) ])]);
var stmt = SEQ ([ NT "expr", STR ";", REDUCE ("STMT",2)]);
and finally using a DSSL (domain specific sub language):
gramlib xlib {
expr = expr "+" term {REDUCE ("PLUS",3)} | term;
term = term "*" factor {REDUCE ("MUL",3)} | factor;
factor = factor "^" atom {REDUCE ("EXP", 3)} | atom;
atom =
| "(" expr ")" { REDUCE ("GROUP",3) }
| "9" { REDUCE ("DIGIT", 1) }
;
stmt = expr ";" { REDUCE ("STMT",2) };
}
Just for fun here is the specification for the DSSL:
priority
palt_pri # "_1";
plibrary := "gramlib" sname "{" plibentry* "}" =>#
"""
(let*
(
(tup (ast_tuple ,_sr ,_4))
(v (ast_apply ,_sr (,(nos "list") ,tup)))
)
(ast_var_decl ,_sr ,_2 ,dfltvs none (some ,v))
)
"""
;
plibentry := sname "=" pexpr[palt_pri] ";" =>#
"""(ast_tuple ,_sr (,(strlit _1) ,_3))""";
sexpr := "parser" "(" pexpr[palt_pri] ")" =># "_3";
private pexpr[palt_pri] := "|"? pexpr[>palt_pri] ("|" pexpr[>palt_pri])+ =>#
"""(ast_apply ,_sr (
,(qnoi 'Parser_synlib 'ALT)
(ast_apply ,_sr (,(noi 'list) ,(cons _2 (map second _3))))))"""
;
private pexpr[pseq_pri] := pexpr[>pseq_pri] (pexpr[>pseq_pri])+ =>#
"""(ast_apply ,_sr (
,(qnoi 'Parser_synlib 'SEQ)
(ast_apply ,_sr (,(noi 'list) ,(cons _1 _2)))))"""
;
private pexpr[patom_pri] := "(" pexpr[palt_pri] ")" =># "_2";
private pexpr[patom_pri] := String =>#
"""(ast_apply ,_sr ( ,(qnoi 'Parser_synlib 'STR) ,_1)) """
;
private pexpr[patom_pri] := "#EPS" =>#
"""(ast_apply ,_sr ( ,(qnoi 'Parser_synlib 'EPS) ())) """
;
private pexpr[patom_pri] := sname=>#
"""(ast_apply ,_sr ( ,(qnoi 'Parser_synlib 'NT) ,(strlit _1))) """
;
private pexpr[patom_pri] := "{" sexpr "}" =># "_2";
}
which uses the following library support:
class Parser_synlib
{
open Parsers;
open Grammars;
fun NT (s:string) => Recog (Nonterminal [pgram_t] s);
fun STR (s:string) => Recog (Strng [pgram_t] s);
fun REDUCE (s:string, n:int) => Action[pgram_t] (Reduce (s,n));
fun ALT (ls: list[pgram_t]) => Recog (Alt[pgram_t] ls);
fun SEQ (ls: list[pgram_t]) => Recog (Seq[pgram_t] ls);
fun EPS () => Recog (Epsilon[pgram_t]);
}
Using this machinery has greatly improved my ability to construct syntax error free grammars for testing my parser, and allowed extensions to be incorporated easily.
The point is the (Felix) grammar extensions automate boilerplate constructions systematically. They turn the particular domain's algebra represented in a functional algebra which is way too powerful for the job, and hence require lots of boilerplate, into a much simpler algebra by a syntactic mapping, which is itself driven by a syntactic algebra (namely the grammar extensions).
### Error messages on mud
it's really confusing when I get errors because my Ocaml embedded Scheme processor (OCS Scheme) is not very good with error messages.
Error messages keep turning up as an issue; perhaps they're a clue to something. Key to a really good error message, methinks, is that it has a human element shining through it that simply cannot be generated formally; that element has to come from the human programmer who wrote the code in the first place. This means the language processor has to preserve the human element through everything that happens to the code up through the moment when the error message gets generated; but while this takes a well-designed language processor, I'm not so sure all languages can support such a processor. Maybe we should be asking what properties of a language allow this sort of humanity-preserving error messaging.
### Errors
I agree. And some algorithms seems better suited to good error reporting than others.
I'm building a parser at the moment that uses coroutines and explores all paths. In principle, the parse fails if no path makes it to the end of the string. I have no idea how to explain an error other than "Syntax Error" without even being able to give a location.
Compare this with a GLR algorithm, where when the parse fails, it does so at a particular location. You can still only say "Syntax error at line 20 column 3" but that's better than "We can't find a parse".
This is also why I dislike HM type inference.
### re: Errors
PEG.js has an interesting solution to reporting errors. It reports a syntax error, but it also outputs a list of terminals which were expected to be parsed at the maximum location it reached while parsing.
### Menhir's error support
Thanks to the work of Frédéric Bour and François Pottier, the LALR parser generator Menhir now supports the "manually write a custom error message for each possible error state of the automaton" (attributed to Clinton Jeffery) approach, and the results are rather good. See:
I have used it on a small grammar for an idealized textual IR, and I had to write 32 error messages. The result is very clear, and although there is some regularity in the error message structures there is no clear way to entirely automate the process.
For example, here is one of the error states described by Menhir on my grammar:
program: BRANCH NIL TRIPLE_DOT ## ## Ends in an error in state: 53. ## ## instruction -> BRANCH expression . label label [ NEWLINE ] ## ## The known suffix of the stack is as follows: ## BRANCH expression ##
and here is my human-written error message:
Parsing an instruction, we parsed "branch <expr>" so far; a label, for example "foo", is now expected to construct a branch instruction "branch <expr> <label> <label>". `
### Deep understanding
It sounds as if one would have to have a fairly deep understanding of the parsing algorithm and the grammar to design the error handling. Supporting fluent handling of that sort is presumably well worthwhile for the results it can produce in situations where that sort of deep understanding is feasible. I'd really like to be able to give a minimal, intuitive description of a grammar and have the parser produce lovely error messages by deriving them from what I provided.
I'm peripherally reminded of a brief anecdote that usually came up during the coverage of LR parsing in compilers classes at my alma mater, concerning the choice of an error message to put in an LR parser table when something really ought to be allowed but isn't; the proposed message was "Error in language design".
### Stability
How stable are these error messages in the face of grammar modifications?
### Early to tell
I have made a couple changes to the grammar yet, but nothing very invasive.
The state numbers will shift a lot, of course, but menhir can keep track of that reliably. The menhir-generated description starts with the terminal stream that gets to the error state, so when you update the error file with the new grammar (menhir has a command to do that) it will robustly find the new error states for each previous error message thanks to this terminal stream (by just running the automaton on it). If some previous errors are not errors anymore, you get told, and if new error states appear they get added to the file.
Another thing that changes is that the description of the error context will change. I changed the grammar to allow explicit newlines in the middle of instructions (previously NEWLINE was a terminal that would terminate instruction), and I got list(NEWLINE) appearing in the middle of the context -- in the places where I inserted them in the grammar.
I think that one think to watch for would be for error states to get merged or split: going from several different possible contexts to one or conversely is going to need you to rewrite your error message. This has not happened to me yet.
(Then menhir provides you some machinery to, for example, mark some symbols to provoke extra reductions when they are at the top of the stack in an error state, which has the effect of "unrolling the context further" and thus have a coarser-granularity error instead of a finer-granularity error, which sometimes is what you want. These advanced aspects are explained in the article on the C error messages that I linked above.)
### Ideally,
one would like to have error messages generated automatically from the grammar in some way that inherently creates lucid diagnostic information by preserving human perspective. The two questions are then what human-perspective information to provide to start with, and how to hang on to it and present it when the error occurs. In those terms, locating error-handling decisions at the parse states is a somewhat downstream option along a spectrum; one might then ask, how might one shift such information upstream to the grammar description, so that when modifying the grammar one would not then have any multiplied considerations of separately modifying the error-handling.
### Indeed, but
Frédéric Bour, an author of the Merlin editor service for OCaml, has implemented an approach going in the description of what you describe. The grammar is annotated with extra information that help reacting to errors. (In the Merlin case, the annotations are not so much to decide an error message as to direct error recovery, that is produce an artificial fix of the parsing state to continue reading the programming buffer and usefully report other errors down the line.)
That said, there is a fundamental tension here : one of the things that the parser generator does is to run a grammar analysis that extracts information that is not, by design, present in the original grammar. This means that you may need to annotate "intent" on things that don't show up, declaratively, in the grammar description.
For example, the ability to write two separate productions that share a common prefix (instead of having to factorize them manually) is part of the core value of LR parser generators, as it lets you write more readable rules. The existence of this sharing will have an error-message impact, as errors in the shared part will have ambiguous continuations -- and this is an information you need to exploit to write a good error message, and generally want to know as a grammar designer. But I don't know where I would attach information for this case in the source grammar.
So I think it is useful to think of separating the error-reporting logic from the nitty-gritty details of the parsing automaton as much as possible, but we should also recognize that said details also play the role of a powerful grammar analysis tools whose information we want to exploit. How to expose this in a better way, I don't know.
If we were thinking of this question as just another case of compiler error reporting (type error, syntax error), one thing we would consider is to ask the grammar author to write a "shared prefix handling clause" somewhere in the grammar (maybe in a part dedicated to grammar errors), and then having a warning or error at compilation time if a mixed-continuation error exists without the corresponding sharing-aware clause, or conversely if a previous sharing clause has been rendered inadequate by a change in the grammar.
### explaining stuff
The approach in my long-ago toy compiler was to produce a diagnostic message saying "here's the part of the source code where the problem happened, this part of it is the partial expression that was being put together, this token here is the one that didn't fit, and these are the sorts of things that would have made sense". Expressed far more compactly and effectively than that; but that's the information it conveyed (as best I recall; alas I don't have a platform set up where I can run it). The technique was probably helped by the fact that the grammar was set up so there was always just one unambiguous choice of what partial expression was being put together at a given point; if there's more than one choice of how many tokens before the current point might be included in the current expression, it would be more difficult to succinctly illustrate what the parser was in the process of doing when the problem was encountered.
### The existence of this
The existence of this sharing will have an error-message impact, as errors in the shared part will have ambiguous continuations -- and this is an information you need to exploit to write a good error message, and generally want to know as a grammar designer. But I don't know where I would attach information for this case in the source grammar.
You could attach it to the enclosing alternative. Let's say you have a piece of grammar A B | A C, but the input is A D. You could attach error messages to the B and C nodes in the grammar that give an explanation of why the parse failed if the last hope of parsing the string died there. Such nodes would have type Parser where T is the value of the node if successfully parsed, and E is the type of error. By default the error type could be a pair (n:Int, errormsg:Str) where n indicates how far into the input string we got. The default error combiner for | could take the errors from both branches and choose the one with largest n. If both branches have the same n, display both (as in "We parsed up to {n}, and were expecting B or C, but got D"). If you a custom error message for the shared prefix you could write a custom error combiner on the | node (and change the error type for the B and C nodes from strings to something you can analyse programmatically in the error combiner).
### A custom error combiner on
A custom error combiner on the | node would seem to expect an explicit branch. Grammars tend to introduce alternatives by simply having multiple grammar rules existing in parallel, in which case the choice is implicit. One might of course provide a custom error combiner for implicit choice; that seems rather... broad in scope, for customization.
### Those implicit choices are
Those implicit choices are always associated with a named grammar rule, so you could attach the error combiner to the rule.
### Let's say
Let's say we've got
A -> B !
A -> B , A
B -> C ( D )
B -> C [ D ]
We parse a C, and then instead of a "(" or a "[" we find a semicolon. Which rule would the error combiner be attached to?
B
### Oh.
Thanks. That clarifies things; I would have said that's a nonterminal, rather than a rule, hence my momentary confusion. If you're willing to attach the error handling to (what I would call) a nonterminal rather than to an operator, that does limit it scope — though one might wonder if the scope might then be too narrow.
### Functions as records
I have found it reasonable to treat records (and arrays, and lists, etc) as particular kinds of function closure. You call them with arguments (keys to look up) and they return results (data stored at that key). And there's a binding procedure that you call with a record, key and a value as arguments which stores the value into the closure at that key.
Closures, however, are not my favorite kind of function. Their semantics rapidly get ugly.
FWIW, I share the opinion that improper lists are not needed or wanted as program representation in Lisps.
### Bidirectional operations
I started with numbers. My base language has support for natural numbers and texts. But in a view I can translate between expressions like "#0 #3 integer" and "-3". "3 #5 ratio" to "3/5" in the view. And "3141 -3 decimal" to "3.141". (Here I use #3 in the view for natural numbers, but that translates to plain 3 in the source.)
My underlying language doesn't support comments. But I can model comments in views in terms of simply dropping a text. Comment-like structures can also support qualified namespaces and other view hints.
The translation for local variables and lexical closures is a bit more involved, derived from proof of equivalence between SKI and lambda calculus. I blogged about it recently. It was finding this translation, and how simple it was, that finally convinced me this approach was really doable.
Once we have variables, infix notations aren't difficult. We can simply translate between "A B op" and "(A op B)" for a known set of operator-like words whenever A and B are variables, values, or themselves infix expressions. (We could further leverage operator precedence to eliminate unnecessary parentheses... but I personally never use operator precedence in my code.)
I have also experimented with concise expression of sequences, useful for lists, data, continuation passing code. A sequence translate between "[[a] {b,c} cons]" and "{a, b, c}". And "[[c] nil cons]" becomes "{c}".
Note how, for both sequence and numbers, I derive views from other views, incrementally building towards higher level expressions. I've found this a very convenient strategy, and it means we still have a comprehensible presentation like "2 #3 ratio" if a particular view fails to support rational numbers.
Editable views are also very useful for translating secure hashes to human comprehensible names. My language can link code and binaries and hierarchical codebases by secure hash, which is convenient for some code sharing and structure sharing patterns.
### Cool
I like this idea a lot! Please report back as you make progress!
### Having seen C++
I thought Stroustrup's Rule was There's always enough room for another kitchen sink.
### This has some implications about minimal-syntax languages.
Stroustup's rule if applied to minimal-syntax languages (lisps, forths, etc) implies that all features are established features.
And indeed programmers in those languages DO treat all features as primitives. Lisp programmers use fairly deep concepts of semantics in casual, flexible, fluent ways. I hear the same thing is true of forth programmers.
It makes me wonder whether having the language structure enforcing minimal syntax on everything is somehow facilitating programmers in getting used to new things. Just the fact of *NOT* having the syntax call them out as not being remarkable or exceptional, might help programmers not *think* of them as remarkable or exceptional.
### Interesting
Lisp programmers use fairly deep concepts of semantics in casual, flexible, fluent ways. I hear the same thing is true of forth programmers.
I'm not completely sure what you are talking about. Would you mind giving a few examples?
### Well, okay...
Procedures as values that can be held in variables, stored in structures, etc.
Persistent closures.
Programs as expressions.
Functional programming.
Persistent closures as objects, long before OO became popular elsewhere.
Lambda and anonymous procedures.
'map' back before it was cool and all the kids started doing it.
Procedures with mutual recursion.
Macros and general translation of data into code.
Macros that generate macros.
Reflective interpreters.
Enumerations and generic accessors, long before it was cool and all the kids were doing it.
Distinguished equality predicates that test for different *kinds* of equality.
Type of an entity as an idea distinct from its storage format in memory.
And the list goes on. Each of these things emerged and became accepted practice treated as primitives, very *early* in Lisp history, for the most part long before programmers elsewhere started using them, and it seems to my (subjective, probably biased) memory that Lisp programmers got *comfortable* with these concepts much more rapidly than (later) programmers who encountered them using languages where loud syntax called them out.
### Counter example
As an occasional Scheme user I would guess that this rigid simplicity calls apart when one needs an extension domain not well supported by the syntax. I may be wrong but the thing I miss in Scheme is pattern matching.
I can pattern match manually in Scheme but it seems really messy. In Ocaml, its relatively simple. Racket is a Scheme with pattern matching, but it required an actual syntax extension if I understand correctly. Scheme macros don't do the job, because they're not recursive, pattern matching is.
### Pattern matching....
I remember thinking pattern matching was a problem in Lisp. Then I started using OPS5 Lisp when I needed pattern matching and the problem went away. :-)
Alternatively there's a package of macros that does essentially the same thing as a reflective interpreter extending scheme.
### Rigid simplicity
The classic "ball of mud" quote about Lisp works so well because it captures something about Lisp that's very hard to put into words. Lisp's simplicity isn't rigid.
### Pattern matching implemented in macros
If the Scheme supports something like defmacro, then a macro can call a procedure during macroexpansion, and that procedure can be recursive. That procedure can implement a custom notion of macroexpansion, or indeed its own whole compiled language.
Pattern matching is a good example of where that comes in handy. To write a macro where one part of the macro body is a pattern, we want to know what local variables are bound by that pattern so we can expand into a let or lambda with those variables. If we're willing to invoke a user-defined macroexpander on the pattern, we can design that macroexpander so that part of its expansion result is a set of variables.
Lisps often use macros as simple sugar for higher-order function calls, but a language which already has convenient lambdas doesn't need macros for that. I think macros pay off once we want to do a tree traversal, like we do with a macro for pattern matching.
### Will just leave these here…
Something different for Xmas: "stealth Lisps" that allow white space in identifiers:
|
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https://math.stackexchange.com/questions/3508666/triangle-interpolation-with-6-control-points
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# Triangle interpolation with 6 control points?
Through a costly simulation, I am able to calculate the value of a function at several discrete points on a plane. My task now is to interpolate, to find the values at all points of the grid. (It is a simulation of a sheet of rubber, with the sheet tessellated with a triangle grid.)
Now I have seen some similar questions on the site, on how to interpolate within a triangle, and the consensus seems to be to use barycentric coordinates. I have implemented this, and the result is shown on the left/top. For comparison, a result using the inverse of the distance to get the weights resulted in the picture on the right/bottom.
(I have not explicitly visualised the nodes, but from the second picture it's pretty obvious, where they are.)
Now, although the result with barycentric coordinates is not bad, esp. when compared to the other result, I'm not completely satisfied. Notice how the triangular/hexagonal structure is very visible, for example the bright lines emanating from the yellow spot.
My question: is there a better weighting function?
I strongly assume there is nothing better that only takes the 3 given control points into consideration, but I was wondering if there is a weighting function that uses the 6 nearest control points, so A-F instead of A-C in this figure:
Though there is a section on 'generalised' barycentric coordinates on the wikipedia site, I can't say it's something I understand how to apply. I've also looked at bicubic interpolation, but that is only possible on a square or rectangular grid.
Many thanks!
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https://math.stackexchange.com/questions/2358635/integral-without-divergence-theorem
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# Integral without Divergence Theorem
I wish to solve the following integral(Ans. $108\pi$)
$$\iint_S \vec F\cdot \hat{n}dS$$ Where
$$\vec F=4xz\hat{i}+xyz^2\hat{j}+3z\hat{k}$$
and $S$ is the surface of the region above the $xy$ plane bounded by the cone
$$z^2=x^2+y^2$$
and the plane $z=3$
My attempt:
Everything in Spherical Coordinates,
Here,
$$r\in[0,3\sqrt{2}]$$
$$\theta=\frac{\pi}{4}$$
$$\phi\in[0,2\pi]$$
$$dS=r\sin(\theta)d\phi dr=\frac{r}{\sqrt{2}}d\phi dr$$
$$\vec F=4r^2\sin(\theta)\cos(\phi)\cos(\theta)\hat{i}+r^4\sin^2(\theta)\cos(\phi)\sin(\phi)\cos^2(\theta)\hat{j}+3r\cos(\theta)\hat{k}$$
The $\hat{n}$ can be calculated using gradient
$$\vec{\nabla}(x^2+y^2-z^2)=2(x\hat{i}+y\hat{j}-z\hat{k})$$
$$|\vec{\nabla}(x^2+y^2-z^2)|=\sqrt{4(x^2+y^2+z^2)}=2r$$
$$\hat{n}=\frac{\vec{\nabla}(x^2+y^2-z^2)}{|\vec{\nabla}(x^2+y^2-z^2)|}=\frac{x}{r}\hat{i}+\frac{y}{r}\hat{j}-\frac{z}{r}\hat{k}=\sin(\theta)\cos(\phi)\hat{i}+\sin(\theta)\sin(\phi)\hat{j}-\cos(\theta)\hat{k}$$
Now,
$$\vec{F}\cdot\hat{n}=4r^2\sin^2(\theta)\cos^2(\phi)\cos(\theta)+r^4\sin^3(\theta)\cos(\phi)\sin^2(\phi)\cos^2(\theta)-3r\cos^2(\theta)$$
$$\vec{F}\cdot\hat{n}=\frac{4r^2\cos^2(\phi)}{(\sqrt{2})^3}+\frac{r^4\cos(\phi)\sin^2(\phi)}{(\sqrt{2})^5}-\frac{3r}{2}$$
$$\vec{F}\cdot\hat{n}dS=(r^3\cos^2(\phi)+\frac{r^5\cos(\phi)\sin^2(\phi)}{8}-\frac{3r^2}{2\sqrt{2}})drd\phi$$
$$\iint_S \vec F\cdot \hat{n}dS=\int_{0}^{2\pi}\int_{0}^{3\sqrt{2}}(r^3\cos^2(\phi)+\frac{r^5\cos(\phi)\sin^2(\phi)}{8}-\frac{3r^2}{2\sqrt{2}})drd\phi$$
$$\iint_S \vec F\cdot \hat{n}dS=\int_{0}^{2\pi}[\frac{r^4\cos^2(\phi)}{4}+\frac{r^6\cos(\phi)\sin^2(\phi)}{48}-\frac{r^3}{2\sqrt{2}}]_{0}^{3\sqrt{2}}d\phi$$
$$\iint_S \vec F\cdot \hat{n}dS=\int_{0}^{2\pi}[81\cos^2(\phi)+\frac{3^6\cos(\phi)\sin^2(\phi)}{6}-27]d\phi$$
$$\iint_S \vec F\cdot \hat{n}dS=81\int_{0}^{2\pi}\cos^2{\phi}d\phi+\frac{3^6}{6}\int_{0}^{2\pi}\cos(\phi)\sin^2(\phi)d\phi-27\int_{0}^{2\pi}d\phi$$
$$\iint_S \vec F\cdot \hat{n}dS=81\pi+0-54\pi=27\pi$$ What is wrong ??
EDIT: It looks like I forgot the top cap !! (Thanks to StackTD) For the upper cap we have
$$z=3$$
$$\hat{n}=\hat{k}$$
$$\vec{F}.\hat{n}=\vec{F}.\hat{k}=3z=9$$
$$\iint_S\vec{F}.\hat{n}dS=\iint_S9dS=9\iint_SdS=9\times area=9\times\pi(3)^2=81\pi$$
Total
$$27\pi+81\pi=108\pi$$
• Cylindrical coordinates looks to be a better choice here. – Paul Jul 14 '17 at 14:08
• There are 2 surfaces which have to be integrated separately also. – Paul Jul 14 '17 at 14:09
• Which is the second surface? Isn't this the only surface? – Nishant Garg Jul 14 '17 at 14:10
• The top of the surface, i.e. the "cap" of the cone, given by the plane $z=3$. At least, if $S$ is supposed to be this closed surface (that would lead to $108\pi$). – StackTD Jul 14 '17 at 14:16
• Ah, thanks!!! I solved it because of your help @StackTD – Nishant Garg Jul 14 '17 at 14:30
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https://datascience.stackexchange.com/questions/9458/nlp-opinion-mining-vs-sentiment-analysis/9461
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# nlp - opinion mining vs sentiment analysis
I have been told that nlp possibly holds the key for allowing researchers to infer the affective state of a person when writing. For instance, by using nlp analysis on online note taking you could infer whether a student is stressed. I work in educational cognitive science, so if this were the case it would be a valuable resource for me, however I am struggling to find evidence that this is indeed the case.
I have begun preliminary research and am trying to learn a bit about the technical aspects of nlp - I'm taking an online course by Jurafsky and Manning, another by Michael Collins - and I have been reading about what what can be inferred using nlp, specifically around opinion mining and sentiment analysis.
My question is two part:
• Firstly, most resources I have come across say something along the lines of nlp can be used for opinion mining and sentiment analysis and we will talk about the implications for opinion mining'. Can someone point me in the direction of more sentiment analysis oriented resources?
• Secondly, as I understand it, sentiment analysis is deriving the stated sentiment within text, e.g. I was happy with, I loved, was tasty, enjoyed, hated, frustrated, etc. Can nlp, or something else, be used to derive unstated affect? And is this the same thing as sentiment analysis?
[Apologies if this is asked in the wrong exchange. I've been trying to find the best fit, but there were a few candidates and I wasn't sure which would be most appropriate.]
• Alice, it is perfectly on-topic here; and it's a very nice question. Welcome to the site :) – Dawny33 Dec 21 '15 at 12:30
I think the key is that most Recurrent Neural Networks problems are formulated in terms of either a regression (with low values indicating negative sentiment, and high values positive) or a binary classification (is this text positive?).
What you seem to be interested in is a much more nuanced definition of sentiment. This doesn't present any inherent problem, as the same algorithms might well work to predict more complex sentiments. The issue is simply labeled data. Because this kind of classification is difficult even for humans, it isn't easy to reliably gather data on, say, how stressed a writer is.
However if you're interested in assembling a dataset of that nature, you'd be able to apply the same methods (Recurrent Neural Networks are a popular option) to do the classification. Many researchers in the field use Amazon Mechanical Turk or something similar to gather labeled data at a reasonable cost.
Can someone point me in the direction of more sentiment analysis oriented resources?
There are tonnes of exceptionally good papers on sentiment analysis for your reference. Especially the ones on social network sites like Twitter.
However, I think the book by Manning and his course are a nice start as references to NLP and opinion mining.
Can nlp, or something else, be used to derive unstated affect?
Yes, it can be. This would be my approach:
(Consider I already have a hand-classified training data) Using the bag of words approach, the most used words and phrases for a mood (stressful, jovial, etc) can be captured, and the subsequent training data can be ranked accordingly as (60% stressful, 40% jovial).
Additionally, you can also define thresholds for getting a single mood. Like:
if mood[score] > .5:
current_mood = mood
Sentiment analysis, sentiment detection and opinion mining all cover a set of problems, and can generally be considered to be one and the same.
The term sentiment analysis seems to be more popular in the press and in industry. In practice, as of 2015, it is mostly about giving a score, to text, between 0.0 and 1.0, for negative to positive sentiment. (Strictly speaking that is only a subproblem and one of many possible formulations.)
But whenever any of the terms is used, you should define or ask for definition of the exact problem.
|
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https://indico.desy.de/event/12482/contributions/9138/
|
# XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS16)
Apr 11 – 15, 2016
DESY Hamburg
Europe/Berlin timezone
## Diffractive production of heavy mesons at the LHC within k_t -factorization approach
Apr 13, 2016, 4:30 PM
15m
SR2 (DESY Hamburg)
### SR2
#### DESY Hamburg
Small-x, Diffraction and Vector Mesons
### Speaker
Dr Marta Luszczak (University of Rzeszow)
### Description
We discuss diffractive production of open charm and bottom mesons at the LHC [1]. The differential cross sections for single- and central-diffractive mechanisms for c ̄c and b ̄b pair production are calculated in the framework of the Ingelman-Schlein model corrected for absorption effects. In this approach one assumes that the pomeron has a well defined partonic structure, and that the hard process takes place in a pomeron-proton or proton-pomeron (single diffraction) or pomeron-pomeron (central diffraction) processes. Here, leading-order gluon-gluon fusion and quark-antiquark anihilation partonic subprocesses are taken into consideration. Both pomeron flux factors as well as parton distributions in the pomeron are taken from the H1 Collaboration analysis of diffractive structure function and diffractive dijets at HERA. The extra corrections from subleading reggeon exchanges are explicitly calculated and are also taken into consideration. Predictions for single- and central-diffractive production in the case of inclusive D and B mesons, as well as D ̄D correlations are presented, including detector acceptance of the ATLAS, CMS and LHCb Collaborations. The experimental aspects of possible standard and dedicated measurements are carefully discussed. For the first time, the differential cross sections for the diffractive c ̄c pair production are calculated in the framework of the k_t -factorization approach, i.e. effectively including higher-order corrections. The unintegrated (transverse momentum dependent) diffractive parton distributions in proton are calculated with the help of the Kimber-Martin-Ryskin prescription where collinear diffractive PDFs are used as input. The latter are obtained by means of the Ingelman-Schlein model. Several quark-level differential cross sections are shown, including one-dimensional distribution and two-dimensional correlation distributions (e.g. φ_ {c ̄c} - azimuthal angle correlations or pair transverse momentum p_t distributions. The hadronization of charm quarks is taken into account by means of fragmentation function technique. Predictions for single-diffractive production of D^0 meson including detector acceptance of the ATLAS experiment are presented. Crucial aspects of possible standard and dedicated measurements within the ATLAS detector are also discussed. [1] M. Luszczak, R. Maciula and A. Szczurek, Single- and central-diffractive production of open charm and bottom mesons at the LHC: theoretical predictions and experimental capabilities, Phys. Rev. D 91 (2015), 054024. [2] M. Luszczak, R. Maciula, A. Szczurek and M. Trzebinski, Diffractive charm production at the LHC within k_t -factorization approach, a paper in preparation. E-mail: [email protected]
### Primary author
Dr Marta Luszczak (University of Rzeszow)
### Co-authors
Prof. Antoni Szczurek (Institute of Nuclear Physics, Polish Academy of Sciences) Dr Rafal Maciula (Institute of Nuclear Physics, Polish Academy of Sciences)
Slides
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http://rin.io/oriented-cobordism-cohomology/
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# Oriented Cobordism Cohomology
Edit: When I say cobordism, I mean oriented cobordism unless stated otherwise. Also note that I accidentally flip-flopped $\Omega^*$ and $\Omega_*$ — $\Omega^n$ should be cobordism classes of maps from manifolds of codimension $n$ to $X$, and $\Omega_n$ is cobordism classes of maps from manifolds of dimension $n$ to $X$.
Let’s say $M_1, M_2,$ and $X$ are differentiable manifolds. We have a map $f_1$, and a map $f_2$.
Let’s think of a movie:
Our first frame is the map from $M_1\to X$
Our last frame is the map from $M_2 \to X$
What is in between? The instructions for how to deform $M_1 \to X$ to look like $M_2 \to X$.
Each movie frame is a map from $M \to X$, which we can stack up (like a CT-scan — such that the first frame is $M_1 \to X$, and the last is $M_2 \to X$) to get another map, $W \to X \times [0,1]$ which is “bounded” by the first and last map: $[0,1]$ is our time interval.
If such a $W$ exists, $M_1 \to X$ and $M_2 \to X$ are “cobordant” (same boundary), and $W$ is their “cobordism” (the manifold that has them as its boundary). It’s just an equivalence relation.
Note that we can also play with cobordism without $X$ by looking at cobordism classes of $n$-dimensional oriented manifolds.
Note that the pair of pants is just an aesthetically pleasing example of a cobordism, and there are many other examples!
Let’s make something using the recipe:
1. Take in a manifold $X$
2. Look the collection of maps from $n$-dimensional oriented manifolds to $X$ (up to cobordism of maps)
3. Equip the collection with connected sum.
4. Output: $n$-dimensional oriented cobordism group (wrt X).
$\Omega^*(X)$ is the slice category $\text{Man}/X$, up to cobordism of maps.
Why are the non-trivial groups $\Omega^{2n}(-)$? I’ve been told that all manifolds with odd dimension are nilbordant, but I’m not sure I believe this.
But this is just a group! Let’s make it a ring! This particular ring is called “Thom’s ring” in the literature.
1. Take in a manifold $X$
2. Look the collection of maps from $n$-dimensional oriented manifolds to $X$ (up to cobordism of maps) for all $n \in \mathbb{N}$
3. Equip the collection with connected sum and cartesian product.
4. Output: oriented cobordism ring (wrt X).
The graded ring $\Omega^*(-)$ is a cohomology theory (graded by dimension).
Notational aside: $MU^*(-)$ and $\Omega^*_{U}$ are alternative notations for $\Omega^*(-)$ used in the literature.
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http://wwww.thermalfluidscentral.org/encyclopedia/index.php/Maxwell_Relations
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# Maxwell relations
(Redirected from Maxwell Relations)
The fundamental thermodynamic relation for a reversible process in a single-component system, where the only work term considered is pdV, is obtained from eq. $dE \le TdS - \delta W$ from Thermodynamic property relations, i.e.,
$dE = TdS - pdV\qquad \qquad(1)$
which can also be rewritten in terms of enthalpy (H = E + pV), Helmholtz free energy (F = ETS), and Gibbs free energy (G = HTS) as
$dH = TdS + Vdp\qquad \qquad(2)$
$dF = - SdT - pdV\qquad \qquad(3)$
$dG = - SdT + Vdp\qquad \qquad(4)$
which all have the form of
$dz = Mdx + Ndy\qquad \qquad(5)$
Where
$M = {\left( {\frac{{\partial z}}{{\partial x}}} \right)_y}\qquad \qquad(6)$
$N = {\left( {\frac{{\partial z}}{{\partial y}}} \right)_x}\qquad \qquad(7)$
and dz is an exact differential, as thermodynamic properties like E,H,F, and G are path-independent functions.
Since eq. (5) is the total differential of function z,M and N are related by
${\left( {\frac{{\partial M}}{{\partial y}}} \right)_x} = {\left( {\frac{{\partial N}}{{\partial x}}} \right)_y} = \frac{{{\partial ^2}z}}{{\partial x\partial y}}\qquad \qquad(8)$
Applying eq. (8) to eqs. (1) – (4), the following relationships are obtained:
${\left( {\frac{{\partial T}}{{\partial V}}} \right)_S} = - {\left( {\frac{{\partial p}}{{\partial S}}} \right)_V} \qquad \qquad (9)$
${\left( {\frac{{\partial T}}{{\partial p}}} \right)_S} = {\left( {\frac{{\partial V}}{{\partial S}}} \right)_p}\qquad \qquad(10)$
${\left( {\frac{{\partial S}}{{\partial V}}} \right)_T} = {\left( {\frac{{\partial p}}{{\partial T}}} \right)_V}\qquad \qquad(11)$
${\left( {\frac{{\partial S}}{{\partial p}}} \right)_T} = - {\left( {\frac{{\partial V}}{{\partial T}}} \right)_p}\qquad \qquad(12)$
which are referred to as Maxwell relations. The goal of Maxwell relations is to find equivalent partial derivatives containing p,T, and V that can be physically measured and therefore provide a means of determining the change of entropy, which cannot be measured directly.
## References
Faghri, A., and Zhang, Y., 2006, Transport Phenomena in Multiphase Systems, Elsevier, Burlington, MA.
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https://pixmob.info/what-is-the-square-root-of-79/
|
# What Is The Square Root Of 79
What Is The Square Root Of 79. The term can be written as ²√75. 79 or 75. 79^1/2. As the index 2 is even and 75. 79 is greater than 0, 75. 79 has two real square roots: ²√75. 79, which is positive and called principal square root. Find the square root of 79. 18.
## Square Root of 79 – How to Find the Square Root of 79? – Cuemath
√ is called radical symbol or radical only. Second root of 6. 79 =. 4 rowssquare root of 79.
2 is the index. The radicand is the number below the radical sign. Square root = ±2. 6057628442.
## Square Root of 79 – How to Find the Square Root of 79? – Cuemath
25 rowsproof that the square root of 79 is 8. 88819441731559. The square root of 79 is defined as the. 25 rowswhat is square root?
The square root of 79 is expressed as √79 in the radical form and. A perfect square is a number with an integer as its square root. This means that it’s a product of an integer with itself. In decimal representation, the square root of 72 is 8. 485 when rounded to.
### SQUARE ROOT OF 79
#inhindi vargmul kaise nikalte hain #squarerootof √1000 youtu.be/GZImvqJS7io √361 youtu.be/w5A1ldaep1o √23 youtu.be/ThD8xf_24zE √676 youtu.be/5GyIqP1tYrA √441 youtu.be/p9kuUFlFG7k v108 youtu.be/Nd4ihDeL-RE √729 youtu.be/F5aT2Ae78vE √500 youtu.be/9DmQzU-cjOY √216 youtu.be/sBF4NBo6rR0 √10000 youtu.be/MBRGech-kNE Find The Square Root youtu.be/kbaKXZDrZlQ √1225 youtu.be/vIQS_xRA2bY √1296 youtu.be/6qJ_lO9fApw √1024 youtu.be/IRmWgrKrtko √841 youtu.be/aordsEZ46Lw 1 vargmul kaise nikale Teacher Name- Surendra Khilery . √1225 youtu.be/vIQS_xRA2bY √1296 youtu.be/6qJ_lO9fApw √1024 youtu.be/IRmWgrKrtko √841 …
## Conclusion
🐯 Step-by-step explanation of how to find the square root of 79. I'll show you how to simplify the square root, write it in simplest radical form, and then how to approximate the decimal value. Here are other ways to write this problem: What is the square root of 79? How do you find the square root of 79? sqrt(79) √79 \sqrt { 79 } The square root of (79). What Is The Square Root Of 79.
What Is The Square Root Of 79. Use this calculator to find the principal square root and roots of real numbers. Inputs for the radicand x can be positive or negative real numbers. The answer will also tell you.
Hi, I'm Kimberly. I have a ton of nicknames.. but you can call me Aki. When Kimberly is not scrapping, she is traveling, blog-hopping, reading, or editing photo shoots. And doing laundry!
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http://userdocs.mrtrix.org/en/3.0.1/reference/commands/fixelreorient.html
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# fixelreorient¶
## Synopsis¶
Reorient fixel directions
## Usage¶
fixelreorient [ options ] fixel_in warp fixel_out
• fixel_in: the input fixel directory
• warp: a 4D deformation field used to perform reorientation. Reorientation is performed by applying the Jacobian affine transform in each voxel in the warp, then re-normalising the vector representing the fixel direction
• fixel_out: the output fixel directory. If the the input and output directories are the same, the existing directions file will be replaced (providing the -force option is supplied). If a new directory is supplied then the fixel directions and all other fixel data will be copied to the new directory.
## Description¶
Reorientation is performed by transforming the vector representing the fixel direction with the Jacobian (local affine transform) computed at each voxel in the warp, then re-normalising the vector.
## Options¶
### Standard options¶
• -info display information messages.
• -quiet do not display information messages or progress status; alternatively, this can be achieved by setting the MRTRIX_QUIET environment variable to a non-empty string.
• -debug display debugging messages.
• -force force overwrite of output files (caution: using the same file as input and output might cause unexpected behaviour).
• -config key value (multiple uses permitted) temporarily set the value of an MRtrix config file entry.
• -help display this information page and exit.
• -version display version information and exit.
### References¶
Tournier, J.-D.; Smith, R. E.; Raffelt, D.; Tabbara, R.; Dhollander, T.; Pietsch, M.; Christiaens, D.; Jeurissen, B.; Yeh, C.-H. & Connelly, A. MRtrix3: A fast, flexible and open software framework for medical image processing and visualisation. NeuroImage, 2019, 202, 116137
Author: David Raffelt ([email protected])
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https://seispy.xumijian.me/usage/rf-sta.html
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# Calculate PRFs for a station¶
## 1. Prepare seismic records order by stations¶
Seismic data including direct P arrival should be trimmed according earthquakes. Meanwhile, the data should be order by stations instead of events. For example, YN001 and YN002 are stations; the SAC files are teleseismic data records of these stations.
event_data/
├── YN001
│ ├── 2018.229.15.35.02.1.sac
│ ├── 2018.229.15.35.02.2.sac
│ ├── 2018.229.15.35.02.3.sac
│ ├── 2018.229.22.06.55.1.sac
│ ├── 2018.229.22.06.55.2.sac
│ │......
├── YN002
│ ├── 2018.229.15.35.02.1.sac
│ ├── 2018.229.15.35.02.2.sac
│ ├── 2018.229.15.35.02.3.sac
│ ├── 2018.229.22.06.55.1.sac
│ ├── 2018.229.22.06.55.2.sac
│ │......
## 2. Calculate PRFs using a simple command¶
### 2.1 Prepare a configure file¶
We should prepare a configure file as following including all parameters that will be set during the calculation. The format is following Python module of configparser
[path]
datapath = Data/Path/to/station_name
rfpath = Result/Path/to/station_name
imagepath = Path/to/images
catalogpath = Path/to/catalog
[search_eq]
date_begin = 20110701
date_end = 20111101
catalog_server = IRIS
magmin = 5.5
magmax = 10
dismin = 30
dismax = 90
[match_eq]
dateformat = %Y.%j.%H.%M.%S
ref_comp = .1.
suffix = SAC
tolerance = 60
offset =
[snr]
noisegate = 5
noiselen = 50
[filter]
freqmin = 0.05
freqmax = 2
[trim]
time_before = 10
time_after = 120
[deconv]
gauss = 2
itmax= 400
minderr = 0.001
[save]
target_dt = 0.01
only_r = no
criterion = crust
## 2.2 Run in command line¶
We have provided the command prf. The usage is shown as:
usage: prf [-h] [-l] [-r COMP] [-s] [-b [BAZ]] cfg_file
Calculating RFs for single station
positional arguments:
cfg_file Path to RF configure file
optional arguments:
-h, --help show this help message and exit
-l use local catalog. Default is false
-r COMP Reverse components: EN, E or N
-s Switch East and North components
-b [BAZ] Correct back-azimuth with minimal energy of T component. "baz"
is specified as half-searching range. Default value is 90 deg
• cfg_file: configure file shown above.
• -l if the argument was specified, a local file of catalog would be used in searching earthquakes.
• -r Reverse the horizontal components. The arguments should be in EN, E or N.
• -s If this option is specified the the East and North components would be changed.
• -b Correct the back-azimuth with minimal energy of T component. the argument would be specified as half-searching range. Default value is 90 deg.
## 3. Initialize a project instance¶
To further understand the procedure of the command prf, we recommend calculating PRFs with writing a Python script as following steps.
First, let’s init a rfinstance. In this instance, we can set parameters, match earthquakes from catalog and calculate PRFs.
from seispy.rf import RF
from os.path import join
from obspy import UTCDateTime
pjt = RF()
## 4. Set parameters¶
Most of parameters are saved in pjt.para. Let’s show all default parameters
print(pjt.para.__dict__)
{'_datapath': '/Users/xumj',
'_rfpath': '/Users/xumj',
'_imagepath': '/Users/xumj',
'_catalogpath': '/Users/xumj/.pyenv/versions/anaconda3-5.3.1/lib/python3.7/site-packages/seispy-1.1.8-py3.7.egg/seispy/data/EventCMT.dat',
'offset': None,
'tolerance': 210,
'dateformat': '%Y.%j.%H.%M.%S',
'date_begin': 1976-01-01T00:00:00.000000Z,
'date_end': 2019-07-11T14:04:15.365860Z,
'magmin': 5.5,
'magmax': 10,
'dismin': 30,
'dismax': 90,
'ref_comp': 'BHZ',
'suffix': 'SAC',
'noisegate': 5,
'gauss': 2,
'target_dt': 0.01,
'phase': 'P',
'time_before': 10,
'time_after': 120,
'only_r': False}
Thus, we can set them in our scripts
pjt.para.datapath = 'Data/Path/to/station_name'
pjt.para.rfpath = 'Result/Path/to/station_name'
pjt.para.suffix = 'sac'
pjt.para.ref_comp = ".1."
pjt.date_begin = UTCDataTime('20180701')
pjt.date_end = UTCDataTime('20190701')
pjt.para.offset = 0
pjt.para.tolerance = 60
or in a configure file as above. When you want to initialize an instance using this configure file, please add the path to RF() as:
pjt = RF(cfg_file='path/to/config')
## 5. Search earthquakes from catalog¶
We use the same process as the SplitRFLab. To match the data records and events, we should search earthquakes with some criteria (period, epicentral distance and magnitude).
### 5.1 Load station information¶
the The station latitude and longitude are absolutely necessary when we are used to search earthquakes. the function will read stla and stlo of SAC header from files in pjt.para.datapath.
### 5.2 Search earthquakes¶
the function provide two method to search earthquakes. use
pjt.search_eq()
to search earthquakes in IRIS Web service with the CMT catalog.
In addition, the function allow to perpare earthquakes from a CMT catalog file (saved to seispy/seispy/data/EventCMT.dat). Use command updatecatalog to update the catalog file.
pjt.search_eq(local=True)
## 6. Associate SAC files with events¶
This is a important step, which allow to link SAC files and earthquakes in catalog. The pjt.para.dateformat, that is a format string as in time.strftime, including datetime infomation will allow to match events in catalog. For example, assuming the filename is 2018.229.15.35.02.1.sac. the pjt.para.dateformat should be %Y.%j.%H.%M.%S.
A reference sac file will read to Associate with events. Thus, file-search-string will help to find real SAC files in data path. In this program file-search-string composed of pjt.para.ref_comp and pjt.para.suffix. The presence of *pjt.para.ref_comp*pjt.para.suffix, such as *.1.*sac in this example, for SAC files will be found.
the pjt.para.offset and pjt.para.tolerance` are used to match the origin time from catalog. The definition are the same as those in SplitRFLab.
• The “offset” is the time duration between the event time and the starting time of your seismograms. Ideally, this offset should be identical to the “request start time” defined in the previous window but the data management center may have sent you data beginning later than requested. The offset value represents this difference.
• The “Tolerance” value in seconds will define the time window within which the program will try to associate a seismic file to an event file, by using either its name or the information contained in the header. It is up to the user to find the best compromise: a value too small will let orphans and a value too large will bring confusion since several files could be associated to a seismic event.
After setting up these parameters, use following command to match data records to the catalog:
pjt.match_eq()
## 7. Pretreatment¶
The process of pretreatment include retrend, bandpass filter, calculating arrival time, reject bad record with low SNR, trim records and rotate components from NE to RT.
### 7.1 Filter¶
We will aply a bandpass filter on seismic records. Two corners should be specified.
• para.freqmin: Pass band low corner frequency.
• para.freqmax: Pass band high corner frequency.
### 7.2 Signal-noise-ratios¶
Bad records will be rejected in this step. We will reject records with SNR < para.noisegate. The SNR was calculated as:
$$SNR = 10log_{10}\left(\frac{A_S}{A_N}\right)$$ where $A_N$ and $A_N$ are root mean squares (RMS) of the waveform in a para.noisrlen time-window before and after theoretical P arrival times, respectively.
### 7.3 Trim¶
The waveforms will be cut in this step before para.time_before and after para.time_after theoretical P arrival times, respectively.
pjt.detrend()
pjt.filter() # default using 'para.freqmin' and 'para.freqmax'
pjt.cal_phase()
pjt.drop_eq_snr() # The threshold used as 'para.noisegate'
pjt.trim() # from 'para.time_before' before P to 'para.time_after' after P
pjt.rotate()
## 8. Calculating PRFs¶
We need parameters of pjt.para.gauss, pjt.para.itmax and pjt.para.minderr to calculate PRFs using iterative time-domain deconvolution method
• pjt.para.gauss: Gauss factor. Default is 2.0
• pjt.para.itmax: The maximum number of iterations. Default is 400
• pjt.para.minderr: The minimum misfit. Default is 0.001
pjt.deconv()
## 9. Save PRFs¶
Save the PRFs to pjt.para.rfpath with some criteria. Two kind of criteria allow to set (i.e., crust or mtz). if the parameter set as None, all of PRFs will be saved.
### crust¶
• The maximum peak should appear berween -2s and 2s
### mtz¶
• The maximum peak should appear berween -5s and 5s
• the maximum amplitudes of PRFs in a 30–120 s window after the direct P are smaller than 30% of the maximum amplitudes of the direct P phases.
pjt.saverf(criterion='crust')
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https://www.physicsforums.com/threads/youngs-modulus-question.216393/
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# Young's Modulus Question
1. Feb 19, 2008
### robsmith82
I seem to be going a bit brain dead here, but in youngs modulus, how are the units in GPa as they are in one of my product specs I've just received?
Lets say we have stress in kN/m^2 and strain has no units, then surely E should be in kN/m^2?
2. Feb 19, 2008
### Mute
Pressure is measured in Pascals, and Pressure is defined as a force per unit area. So, a Pascal is really one Newton per unit area: N/m^2, for instance. So, kN/m^2 = kPa, which of course is just 10^6 GPa.
3. Feb 19, 2008
Doh.
Thanks!
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http://py5dev.ixora.io/developer/build_process.html
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# Build Process#
The py5 library is different from the typical Python library in that the code itself is the output of the meta-programming project py5generator. This approach is necessary because of the size, depth, and complexity of Processing.
## Prerequisites#
You will need to download and install Anaconda. You’ll also need build tools such as make and ant, as well as the source control program git.
## Clone Source Repository from GitHub#
You will need to clone the py5generator repo from GitHub. If you don’t already have the Processing 4 application on your computer, you’ll need to download that too.
On my computer I keep all of the py5 repos together in one directory.
$mkdir pythonprocessing$ cd pythonprocessing
$git clone https://github.com/py5coding/py5generator ## Install Java 17# You will need to have Java 17 installed on your computer and available on your path. Relevant information about how to install the correct version is available on the py5 install page. ## Create Anaconda Environment# Next you will need to create the Anaconda environment. This will install Python packages that go beyond what is necessary for regular py5 use. $ cd py5generator
$conda env create -f environment.yml$ conda activate py5
(py5) $cd .. ## Locate Processing Application# When the build process runs, the code will search for and copy jars from the Processing PDE application directory into a specific location in the destination directory. It is important to download the correct (latest) version of the Processing application. On my machine, I keep the Processing PDE application in ~/INSTALL/processing-4. The Java classes need to be compiled with debug information because the meta-programming code parses the output of javap to inspect the Processing jars and gather information about the relevant public fields and methods. Currently Processing jars are compiled with debug information enabled. If this were to ever change, the build process would need to change to adapt. ## Run the py5 Makefile# Finally, run the Makefile. The processing_dir parameter needs to point to the location of the Processing application. The py5_build_dir parameter is where the generated code will go. (py5)$ cd py5generator
(py5) $make processing_dir=~/INSTALL/processing-4 py5_build_dir=../py5code skip_autopep8=true The Makefile uses realpath. You may need to install the “coreutils” package if you don’t have it on your machine already. The optional skip_autopep8 argument will skip autopep8 formatting of the output code, accelerating the build process. Use this during development. A full build takes under a minute to complete. When this runs you’ll see a lot of logging information appear on the screen. There will be a few warnings about skipping typehints for some Matrix functions, but everything else will be info messages. You should familiarize yourself with the logs so you can spot changes and identify when something goes wrong. The final Makefile step installs the generated code into the active Anaconda environment. At this point the new code will be available for you to use. When the build process detects changes to Processing’s methods and fields, a message will appear in the logs. This process is designed to adapt as the Processing library evolves. Be aware that signature changes to known methods will result in automatic updates to documentation files in the py5_docs/Reference/api_en directory. There is an additional make command for generating reference documentation for the website. (py5)$ make generate_py5_docs py5_website_dir=../py5book py5_api_lang=api_en
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https://math.stackexchange.com/questions/2957570/applying-gronwall-lemma-in-majda-bertozzi-book
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# Applying Gronwall lemma in Majda-Bertozzi book.
I am studying Majda-Bertozzi book about incompressible flows. I have applied Gronwall lemma several times, but I do not know how to do in the following case: We have $$|\nabla v(\cdot,t)|_{L^{\infty}}\le C\left(1+\int_0^t|\nabla v(\cdot,s)|_{L^{\infty}}\right)\left(1+|w(\cdot,t)|_{L^{\infty}}\right)$$ and we must use Gronwall lemma to get: $$|\nabla v(\cdot,t)|_{L^{\infty}}\le|\nabla v_0|_0 \exp\left(\int_0^t|w(\cdot,s)|_{L^{\infty}}ds\right).$$ Thanks a lot!
• Where is this, presumably the energy methods chapter? You must need some constant in the final line right – Calvin Khor Oct 16 '18 at 7:46
• Probably yes. The goal (the proof of the theorem 3.6) is achieved if there is a constant in the final line right. But I do not know how to obtain the rhs of the conclusion. – Alex Oct 16 '18 at 7:57
• If I understand correctly, this is from the paper of Beale-Kato-Majda but the inequality in the paper there is different. projecteuclid.org/euclid.cmp/1103941230 maybe you can figure something out – Calvin Khor Oct 16 '18 at 8:56
$$q(t) \le c(t) + \int_0^t u(s) q(s) ds\implies q(t) \le c(0) \exp\left(\int_0^t u(s) ds\right) + \int_0^t c'(s)\left(\exp\int_s^t u(\tau)d\tau \right)ds$$ To put it in this form, you can set $$q(t) = \frac{|\nabla v(t)|_{L^\infty}}{1+|\omega(t)|_{L^\infty}}, u(t) = C(1+|\omega(t)|_{L^\infty}), c(t) = C$$ Then we have $$\frac{|\nabla v(t)|_{L^\infty}}{1+|\omega(t)|_{L^\infty}} \le C\exp\left(C\int _0^t 1+ |\omega(s)|_{L^\infty}ds \right)$$ i.e. $$|\nabla v(t)|_{L^\infty} \le C (1+|\omega(t)|_{L^\infty})\exp\left(C\int _0^t 1+ |\omega(s)|_{L^\infty}ds \right) = \frac{d}{dt} \exp \left(C\int _0^t 1+ |\omega(s)|_{L^\infty}ds \right)$$ And hence $$\int_0^t |\nabla v(s)|_{L^\infty} ds \le C\exp \left(C\int _0^t 1+ |\omega(s)|_{L^\infty}ds \right)$$ which you can plug into the $$H^m$$ energy estimate (3.79), $$\|u(T)\|_m \le \|u_0\|_m \exp\left(c_m\int_0^T|\nabla v(t)|_{L^\infty} dt \right)$$ to get the required a priori estimate.
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https://scicomp.stackexchange.com/questions/27734/data-for-tracy-widom-distribution/27751
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# Data for Tracy-Widom distribution
I have data for a random variable and I wish to test whether it conforms to the Tracy-Widom distribution. However, the T-W distribution is hard to compute. Is there a readly available table of its values I can just download?
It's actually not all that complicated to calculate the Tracy-Widom CDF just from its definition: see On The Numerical Evaluation Of Fredholm Determinants by Folkmar Bornemann. The Wikipedia page gives the definition as $$F_2(s) = \det(I - A_s),$$ where $A_s$ is the integral operator on $[s,\infty)$ with the kernel $$\DeclareMathOperator{\Ai}{Ai} K(x,y) = \frac{\Ai(x)\Ai'(y)-\Ai'(x)\Ai(y)}{x-y},$$ $$A_s[f](x) = \int_s^\infty K(x,y)f(y)\,\mathrm{d}y.$$
Just going from this, you can take the weights $w_i$ and nodes $x_i$ of any good quadrature rule on the interval $[s,\infty)$, such as the excellent tanh-sinh quadrature, and compute the determinant of the matrix $$\det\big( \delta_{ij} - w_i^{1/2} K(x_i, x_j) w_j^{1/2}\big)_{i,j}.$$ This works because the kernel is smooth.
To make sure this actually works, I wrote the code below (using Julia 0.6): there is a little bit of inaccuracy at $F_2(-8)$, but it's fine otherwise. Most of the time is spent calculating Airy functions, so it should be okay for generating tables of values for future use.
module TracyWidom
using SpecialFunctions
using Base.Test
function K(x, y)
try
if x == y
airyaiprime(x)^2 - x * airyai(x)^2
else
(airyai(x)*airyaiprime(y) - airyaiprime(x)*airyai(y)) / (x - y)
end
catch ex # underflow is not an error here
if isa(ex, SpecialFunctions.AmosException) && ex.id == 4
return 0.0
else
rethrow(ex)
end
end
end
function tanhSinhNodes(s, n=64)
tf = 3.158587875883174 # fzero(t -> log1p(-tanh(pi/2*sinh(t))) - log(eps(typeof(s))), 3.1)
t = linspace(-tf, tf, 2n+1)
u = tanh.(pi/2*sinh.(t))
w = pi/2*cosh.(t)./cosh.(pi/2*sinh.(t)).^2
w * step(t) .* 2./(u-1).^2, s + (u+1) ./ (1-u)
end
function tanhSinh(f, s, n=64)
w, x = tanhSinhNodes(s, n)
dot(w, f.(x))
end
function F2(s, n=128)
w, x = tanhSinhNodes(s, n)
m = length(w)
det([Int(i==j) - sqrt(w[i])*sqrt(w[j])*K(x[i], x[j]) for i=1:m, j=1:m])
end
function test()
@testset "TracyWidom" begin
@testset "tanh-sinh" begin
@test tanhSinh(x -> 1/(1+x^2), 0., 32) ≈ π/2
@test tanhSinh(x -> 1/(1+x^2), 1., 32) ≈ π/2 - atan(1.)
@test tanhSinh(x -> (1+x^2)^-1.25, 2.0, 32) ≈ 0.20885622523501382
end
@testset "F2" begin
@test F2(0.1) ≈ 0.9754704606594619
@test F2(-0.1) ≈ 0.9620142937272265
@test F2(-1.0) ≈ 0.8072142419992853
@test F2(-2.0) ≈ 0.41322414250512257
@test F2(-3.0) ≈ 0.08031955293933454
@test F2(-4.0) ≈ 0.0035445535955092003
@test F2(-5.0) ≈ 2.135996984741116e-5
@test F2(-6.0) ≈ 1.062254674124451e-8
@test F2(-7.0) ≈ 2.639614767246062e-13
@test F2(-8.0) ≈ 1.9859004257636574e-19
@test F2(1.0) ≈ 0.9975054381493893
@test F2(2.0) ≈ 0.9998875536983092
@test F2(3.0) ≈ 0.9999970059566077
@test F2(4.0) ≈ 0.9999999504208784
@test F2(5.0) ≈ 0.9999999994682207
@test F2(6.0) ≈ 0.9999999999961827
@test F2(7.0) ≈ 0.9999999999999811
@test F2(8.0) ≈ 0.9999999999999999
end
end
nothing
end
end
Mathematica has the TW distributions:
http://reference.wolfram.com/language/ref/TracyWidomDistribution.html
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http://export.arxiv.org/abs/2010.11728
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Full-text links:
math.NA
(what is this?)
# Title: A highly efficient and accurate exponential semi-implicit scalar auxiliary variable (ESI-SAV) approach for dissipative system
Abstract: The scalar auxiliary variable (SAV) approach is a very popular and efficient method to simulate various phase field models. To save the computational cost, a new SAV approach is given by introducing a new variable $\theta$. The new SAV approach can be proved to save nearly half CPU time of the original SAV approach while keeping all its other advantages. In this paper, we propose a novel technique to construct an exponential semi-implicit scalar auxiliary variable (ESI-SAV) approach without introducing any extra variables. The new proposed method also only needs to solve one linear equation with constant coefficients at each time step. Furthermore, the constructed ESI-SAV method does not need the bounded below restriction of nonlinear free energy potential which is more reasonable and effective for various phase field models. Meanwhile it is easy to construct first-order, second-order and higher-order unconditionally energy stable time-stepping schemes. Other than that, the ESI-SAV approach can be proved to be effective to solve the non-gradient but dissipative system such as Navier-Stokes equations. Several numerical examples are provided to demonstrate the improved efficiency and accuracy of the proposed method.
Comments: arXiv admin note: text overlap with arXiv:1912.09263, arXiv:2001.00812 Subjects: Numerical Analysis (math.NA); Analysis of PDEs (math.AP) Cite as: arXiv:2010.11728 [math.NA] (or arXiv:2010.11728v1 [math.NA] for this version)
## Submission history
From: Zhengguang Liu [view email]
[v1] Mon, 19 Oct 2020 01:40:39 GMT (3165kb,D)
Link back to: arXiv, form interface, contact.
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https://www.physicsforums.com/threads/neutron-decay.63186/
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# Neutron decay
1. Feb 8, 2005
### m00nd0g68
A neutron at rest in the laboratory spontaneously decays into a proton, an electron, and a small essentially massless particle called a neutrino. Calculate the kinetic energy of the proton and the electron in each of the following cases:
a) the neutrino has no kinetic energy
b) the neutrino has 300keV of kinetic energy and is traveling opposite the proton and the same direction as the electron
c) the neutrino has 300keV of kinetic energy and is traveling perpendicular to the proton and electron, which are traveling opposite of each other.
I have solved part a. But part b I am having a problem with. I understand that the neutrino’s E = K + E0 = K + mc2 = K = 300keV (where mc2 = 0 because it has no mass) but I don’t know how to use this with the energies of the other two. Do I simply subtract the energies of the proton, electron and the given K of the neutrino to get an amount that is a new total energy? On part c how do I handle the 300keV of the neutrino that is traveling perpendicularly to the proton and electron?
Any hints would be appreciated…
moondog
2. Feb 8, 2005
### dextercioby
Though it's obviouly a relativistic problem,maybe some of the ole tricks from Newtonian mechanics would help.Do a vector (momenta) diagram and pay attention when u write the conservation of total momentum,ie.write it in vector form & pay attention with the projections.
This valid for point "b" and especially for point "c".
For the record:it's a (massless) electronic ANTIneutrino.
Daniel.
3. Feb 9, 2005
### Davorak
For relativistic mechanics you have to use
$$E^2 = p^2 +m^2$$
In natrual units, instead of the old E1 + E2 ..En = Etot, you get:
$$E_{after}=E_{before}]$$
$$\sqrt{p_{after 1}^2 + m_{after 1}^2} +\sqrt{p_{after 2}^2 + m_{after 2}^2}... = \sqrt{p_1^2 + m_1^2} +\sqrt{p_2^2 + m_2^2}...$$
Also you still have momentum conservation,
$$P_{after \ 1} + P_{after \ 2} ... = P_1 + p_2 ...$$
Hope this helps. There is the four vector notation for this math that simplifies some of this maybe someone else can post it.
4. Feb 9, 2005
### m00nd0g68
My results so far...
For part a I calculated a kinetic energy of 0.782MeV for the electron and 0.752keV for the proton.
For part b I calculated a kinetic energy of 0.483MeV for the proton and 0.387keV for the proton.
Lastly, for part c I calculated 1.08MeV for the electron and 1.21keV for the proton.
Does that make sense?
moondog
5. Feb 9, 2005
### dextercioby
Are you sure with the numbers,i mean,taking into account the mass ratio,the electron would be 1 million times faster than the proton...
Daniel.
6. Feb 10, 2005
### m00nd0g68
Perpindicular neutrino travel
The main part I am not understanding is how to deal with the perpendicular travel of the neutrino. Since E=K+E0=K+mc^2 and the neutrino is massless this means that E=K=.300MeV. How do I deal with this in the perpendicular direction?
moondog
7. Feb 10, 2005
### Staff: Mentor
There is total (kinetic + rest) energy, a scalar quantity.
An then there is momentum, a vector quantity, with components in 2 dimensions, e.g. x-direction and y-direction. The neutrino has momentum, in the direction of travel, which must equal the momentum components of the electron and proton, which are in the opposite direction.
See also - Neutrino Nuclear Physics (1.04 Mb, 50 pages, Japanese language support not necessary - download with save target as).
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http://math.stackexchange.com/users/47830/misha
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# misha
Unregistered less info
reputation
1
bio website location age member for 2 years, 2 months seen Nov 4 '12 at 3:24 profile views 1
1 Positive $T$ satisfying $\int_T^\infty x^{-\log{x}} dx = \int_0^Tx^{-\log{x}}dx$ 1 Convergence of a series.
# 21 Reputation
+10 Positive $T$ satisfying $\int_T^\infty x^{-\log{x}} dx = \int_0^Tx^{-\log{x}}dx$ +10 Convergence of a series.
# 0 Questions
This user has not asked any questions
# 2 Tags
1 sequences-and-series 1 integration
# 1 Account
Mathematics 21 rep 1
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https://forums.techguy.org/threads/intermittant-mouse-trouble-then-freezing.271629/
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# Intermittant Mouse trouble...then freezing.
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#### IntrexTech
Joined
Sep 8, 2004
Messages
3
Lately I have been experiencing some mouse behaviour problems. I notice that it seems to be sluggish at times and is jerky. Sometimes the mouse will halt and then just go haywire, opening up the startmenu and hopping all about the screen. The longer the system runs it seems to get progressively worse until the mouse pointer just freezes altogether and will not move. The rest of the system works just fine, I can navigate through the system by the keyboard. I just don't know what is causing the problem.
At first I thought perhaps it was a physical problem with the mouse, but decided that if that was so, the problem wouldn't clear up on reboot. I have scanned my system for both virus and spyware and it is currently clean. It is a Logitech Optical Mouse with a PS/2 connector. If anyone has any suggestions it would be much appreciated. The following is a Hijack log of my current settings:
Logfile of HijackThis v1.97.7
Scan saved at 11:13:11 AM, on 9/8/2004
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)
Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe
C:\WINDOWS\System32\cisvc.exe
C:\WINDOWS\system32\gearsec.exe
C:\Program Files\Norton SystemWorks\Norton AntiVirus\navapsvc.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Norton SystemWorks\Norton Utilities\NPROTECT.EXE
C:\PROGRA~1\NORTON~1\SPEEDD~1\nopdb.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\System32\carpserv.exe
C:\Program Files\Common Files\Symantec Shared\ccApp.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\WINDOWS\System32\cidaemon.exe
C:\Program Files\AIM\aim.exe
C:\Program Files\Irfanview\I_VIEW32.EXE
C:\TechieTools\HijackThis.exe
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://start.earthlink.net
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.yahoo.com
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyServer = http=localhost:8080
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
N3 - Netscape 7: user_pref("browser.startup.homepage", "www.yahoo.com"); (C:\Documents and Settings\Intrex\Application Data\Mozilla\Profiles\default\ppwraspw.slt\prefs.js)
N3 - Netscape 7: user_pref("browser.search.defaultengine", "engine://C%3A%5CProgram%20Files%5Cmozilla.org%5CMozilla%5Csearchplugins%5CNetscapeSearch.src"); (C:\Documents and Settings\Intrex\Application Data\Mozilla\Profiles\default\ppwraspw.slt\prefs.js)
O2 - BHO: EarthLink Popup Blocker - {4B5F2E08-6F39-479a-B547-B2026E4C7EDF} - C:\Program Files\EarthLink TotalAccess\PnEL.dll
O2 - BHO: NAV Helper - {BDF3E430-B101-42AD-A544-FADC6B084872} - C:\Program Files\Norton SystemWorks\Norton AntiVirus\NavShExt.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O3 - Toolbar: Pop-Up Blocker - {D7F30B62-8269-41AF-9539-B2697FA7D77E} - C:\Program Files\EarthLink TotalAccess\PnEL.dll
O3 - Toolbar: Norton AntiVirus - {42CDD1BF-3FFB-4238-8AD1-7859DF00B1D6} - C:\Program Files\Norton SystemWorks\Norton AntiVirus\NavShExt.dll
O4 - HKLM\..\Run: [CARPService] carpserv.exe
O4 - HKLM\..\Run: [ccApp] "C:\Program Files\Common Files\Symantec Shared\ccApp.exe"
O4 - HKLM\..\Run: [ccRegVfy] "C:\Program Files\Common Files\Symantec Shared\ccRegVfy.exe"
O9 - Extra 'Tools' menuitem: Sun Java Console (HKLM)
O9 - Extra 'Tools' menuitem: MaxSpeed (HKLM)
O9 - Extra button: AIM (HKLM)
O9 - Extra 'Tools' menuitem: Windows Messenger (HKLM)
O15 - Trusted Zone: www.earthandbeyond.ea.com
O15 - Trusted Zone: www.hotmail.com
O15 - Trusted Zone: www.msn.com
O15 - Trusted Zone: www.pogo.com
#### ~Candy~
Joined
Jan 27, 2001
Messages
103,706
Hi and welcome. Does it act the same way on a different type of surface?
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As Seen On
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https://www.datascience.com/blog/experimenting-the-bayesian-way
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Throughout the course of your career, you may need to quantify the effect of changes you make to a product or service. These changes can be the introduction of a new design to a website, the creation of a new medicine, or even choosing one football player to take a penalty kick for your team over another in the World Cup final. The way we quantify these changes is usually via A/B experiments.
For a website, this entails splitting traffic into two or more variants. Visitors in the A variant see the website’s original design, while those in the B variant see the new design. Now, there are two popular approaches to measuring the differences between theses variants statistically: the frequentist approach and the Bayesian approach.
Traditionally, the frequentist approach prevails. In this approach, you treat the traffic in each variant as a sample of all the traffic you will get in your website’s lifetime. Since we are dealing with samples, the means of the samples can be equal or different due to chance — hence, we must use statistical tests (such as Student t-test), confidence intervals, and p-values to figure out whether this is the case. The difference is statistically significant if we can prove that it is unlikely to be due to chance. If you are taking a frequentist approach, you will have to wait until you collect a certain amount of data before you can determine if a change is statistically significant.
On the other hand, if we use a Bayesian approach, we must think more in terms of beliefs. The probabilities we see in our samples are interpreted as beliefs about how different the two variants are. Beliefs can be initialized using our prior knowledge of our website visitors and updated using data. Rather than discussing whether the difference between the two samples is significant or not, we quantify our beliefs about how different the two samples are.
The key advantage of the Bayesian approach is that it is more intuitive and easy to explain to your stakeholders. You can communicate to them — from day one — the belief you have reached about your samples’ differences. You can then update your belief whenever new data is available, and it is up to you and your stakeholders to decide when you have enough belief in the difference. Additionally, you can make use of prior knowledge you have about your website visitors and plug it into your analysis to reach a quicker conclusion.
The Bayesian approach was not very popular in the past because it involves computationally expensive calculations. However, thanks to the powerful computers at our disposal today, those calculations are much easier to execute than they were 30 years ago.
### Software Requirements
To be able to run this code, you need to have Python installed. I used Python 3 for the code here, but I believe earlier versions should work too. You also need to install NumPy, Pandas, and Matplotlib.
### Probability Distributions
Before we get into how to conduct a Bayesian analysis, it is important to understand probability distributions and what they are used for. As an example, take a soccer match where one team has to make a penalty kick. Player A has made eight kicks before and scored five times, so his accuracy is 62.5%. Meanwhile, Player B made 85 kicks and scored 50 times, and so his accuracy is 58.8%. Is it fair to confidently say that Player A is more accurate than Player B?
Before you answer, ask yourself if you’re equally confident about the numbers in these two scenarios. Since you saw Player B take many more penalty kicks than Player A, you know much more about Player B’s skill than Player A’s. As we will see in the next section, the beta distribution is useful in this case. Not only does it give us rates, it also shows us how confident we are in those rates.
### Beta Distribution
The beta function takes two parameters, alpha (the number of successful penalty kicks) and beta (the number of missed penalty kicks). Of course, we can search the internet for the beta equation and substitute the alpha and beta parameters to plot the distribution. However, there is an easier way: We can ask our computer to generate random samples from the beta using the aforementioned parameters. We then can use those samples to find out anything we want about our distribution, or even compare two distributions to each other. This is called a Monte Carlo method, and given a certain distribution, we can use it and NumPy to generate thousands of samples, then compare the two players’ distributions.
Think of it this way: We are asking Player A to make eight kicks, and then another eight, and then another, all the way up to 10,000 sets of eight kicks. Similarly, for Player B, we are asking him to make 10,000 sets of 85 kicks. Then, we’ll compare the distributions of their penalty kick accuracies. Since we cannot ask the players to make such a huge number of penalty kicks in real life, we will use beta distribution parameterized by each of their scored and missed kicks.
import numpy as np
import pandas as pd
from numpy.random import beta
# How many random samples to generate
N = 10000
# We define alpha and beta for the two distributions
success_a = 5
failure_a = 3
success_b = 50
failure_b = 35
# Generate N samples using the predefined alphas and betas
a_samples = beta(success_a, failure_a, N)
b_samples = beta(success_b, failure_b, N)
# Convert to a Pandas Series for better handling later
a_samples = pd.Series(a_samples)
b_samples = pd.Series(b_samples)
# Plot the two distributions using kernel density estimation
pd.DataFrame(
{
'Player A': a_samples,
'Player B': b_samples,
}
).plot(
kind=’kde’,
title='Beta Distribution',
xlim=(0,1),
)
Now we have a better understanding of how these two players perform. According to the distribution means, Player A (orange) is slightly better than Player B (blue) on average. However, the orange distribution is narrower, which means that we have more confidence that Player B’s accuracy is somewhere above 40% and below 80%, while Player A’s accuracy is all over the place (it can be 20% or even 100%; we're not sure). Obviously, Player A’s accuracy is more likely to be above 60% based on his bigger probability mass. Now, as a coach, you still have a tough choice to make about which player to make the kick — but at least you have a better understanding of your data and how confident you can be in it.
Here are some examples of beta distributions and probability density functions:
When both alpha and beta equal one, we end up with a uniform distribution. Imagine that a player makes two penalty kicks, scores one, and missed the other. In this instance, it’s hard to be certain about his accuracy. However, when another player shoots 10 penalty kicks, scores five, and misses five, we are more certain of the 50% accuracy, even though it is still 50-50 like in the first case. This is why the purple probability density function is higher around 50%. The blue one is higher, narrower, and more certain because we’re working with more data — 30 penalty kicks.
### Binomial Distribution
Another distribution we need to have a look at is the binomial distribution. It answers a different question. Say we know that a player has a penalty kick accuracy of 80%. If he shoots 10 penalty kicks in a row, what are the chances that he will score only one out of all of them? What about the chances of only scoring two or three, and so on? Obviously, he cannot score 2.5 or 3.14 kicks, so the binomial is a discrete distribution.
One might argue that if his accuracy is 80%, then he should score eight out of 10. While the probabilities should indeed peak at eight, there is still a chance that he scores only seven or nine. It is hard to capture the real probability, especially with a low number of kicks.
In the graph below, the probability mass function for players has an accuracy of 20% and 80%, with both of them making 10 penalty kicks. Player A’s probabilities peak at two as expected, while B peaks at eight, but there is still a chance that they score a bit more or less than those numbers out of the 10 kicks.
Since this is a discrete distribution, we represent it with a probability mass function instead of a probability density function. As you can see, the graph is displayed as discrete bars and — since probabilities should add up to one — the sum of the bars’ heights for each player add up to one.
If the same Player A is allowed to make 100 kicks instead of 10, he will have a greater chance of showing his real (in)accuracy. In other words, we will have more certainty around once we've seen 20 correct kicks out of 100, compared to two out of 10, as demostrated in the next figure.
# Python Imports
import numpy as np
import pandas as pd
from numpy.random import binomial
# How many random samples to generate
N = 10000
# Binomial distribution parameters
n_a = 10
p_a = 0.2
n_b = 100
p_b = 0.2
# Generate N samples using the predefined N and p
a_samples = binomial(n_a, p_a, N)
b_samples = binomial(n_b, p_b, N)
# Convert to a Pandas Series for better handling later
a_samples = pd.Series(a_samples)
b_samples = pd.Series(b_samples)
# We get some values around 2 in the A samples
# And some values around 20 in the B sample
# We want to calculate how often each value appears
a_freq = a_samples.value_counts()
b_freq = b_samples.value_counts()
# For better visualisation
# We will pad some of missing frequencies
# We will set them to zero
a_freq = a_freq.reindex(range(11), fill_value=0)
b_freq = b_freq.reindex(range(41), fill_value=0)
# Sine we are calculating probabilities here
# We will divide by the total number of samples (N)
a_hist = a_freq / N
b_hist = b_freq / N
fig, axs = plt.subplots(1, 2, figsize=(16,6))
# We already calculated our histogram,
# So we will use a bar chart here instead.
pd.DataFrame(
{
'Player A; P=20% & n=100': a_hist,
}
).plot(
kind='bar',
title='Binomial Distribution (P=20%; n=10)',
xlim=(0, 10),
ax=axs[0],
)
pd.DataFrame(
{
'Player B; P=20% & n=100': b_hist,
}
).plot(
kind='bar',
title='Binomial Distribution (P=20%; n=100)',
xlim=(0, 50),
ax=axs[1],
)
### Time to Pick the Penalty Kicker
Armed with our knowledge of the beta and binomial distributions, we can decide which player we should chose to take a penalty kick. This same methodology is what you would use to decide what changes to a website are more likely to lead to higher conversions, or what medicine is more likely to cure more patients. What we need to calculate is the true accuracy of a player given the data we have about them. Remember, the player cannot take an infinite number of penalty kicks — only a few dozen, if we are lucky. Consequently, what we are after is an estimate of the player’s accuracy.
Let's call Player A's accuracy $Pr_a(Scores)&space;%0$ with “Pr” representing probability. Similarly, $Pr_b(Scores)&space;%0$ will represent accuracy for Player B. Since we’re looking for an estimate of accuracy, we are after the distribution of these two scoring probabilities, i.e., the distributions of the aforementioned probabilities. We want to get a distribution based on our collected data, so we are looking for conditional probabilities. The probability distribution of the players’ accuracy gives the data we have, or more formally:
$Pr(Pr_a(Scores)&space;|&space;Data)&space;%0$
The pipe “|” here means given, or conditional data.
We can calculate these two probabilities for the two players thanks to Bayes' rule:
$Pr(Pr_a(Scores)&space;|&space;Data)&space;=&space;{Pr(Data&space;|&space;Pr_a(Scores))&space;\times&space;Pr(Pr_a(Scores))&space;/&space;P(Data)&space;}&space;%0$
$Pr(Pr_b(Scores)&space;|&space;Data)&space;=&space;Pr(Data&space;|&space;Pr_b(Scores))&space;\times&space;Pr(Pr_b(Scores))/&space;P(Data)$
Since we are comparing two players, and P(Date) is not a function of either (it is the same for both of them), we can get rid of it in our comparison:
$Pr(Pr_a(Scores)&space;|&space;Data)&space;:=&space;Pr(Data&space;|&space;Pr_a(Scores))&space;\times&space;Pr(Pr_a(Scores))&space;%0$
$Pr(Pr_b(Scores)&space;|&space;Data)&space;:=&space;Pr(Data&space;|&space;Pr_b(Scores))&space;\times&space;Pr(Pr_b(Scores))&space;%0$
I am using := instead of the proportionality sign (∝) for better readability.
### The Prior
$Pr(Pr_a(Scores))&space;%0$ is called the prior, which represents our belief in a player’s accuracy without seeing him take any penalty kicks. Notice that it does not depend on any data. One way to set our prior is to think of what a generic soccer player does. Say we know that on average a player in the first division takes 10 penalty kicks in a season, scores seven times, and misses three kicks. Remember, the beta distribution is meant to provide us with the distribution of rates, given a certain number of successes and failures.
In this case, $Pr(Pr_a(Scores))&space;%0$ can be represented by a beta distribution with$\alpha&space;=&space;7&space;%0$ and $\beta&space;=&space;3&space;%0$. This is called an "informed prior" because we’re using previous information to inform our initial belief. Sometimes, we won't even have prior information about football players to begin with. In that case, we can use an uninformed prior. Remember, if we set both alpha and beta to one, the beta distribution turns into an uninformed one. When we are starting our calculations on such a clean slate, everything is possible!
### The Likelihood
$Pr(Data&space;|&space;Pr_a(Scores))&space;%0$ is called the likelihood. Say we know a player’s accuracy to be 80%, and we have seen him taking 10 penalty kicks and scoring seven times. What is the likelihood that those two facts match? If he only scores twice, will this data match his scoring accuracy less? The binomial distribution is the best way to represent this likelihood. The interesting part is that the likelihood depends not only on how closely the probability we have seen in our data matches the true probability, but also on how much data we collect.
### Conjugate Distributions
Now, we must multiply the prior (beta distribution) by the likelihood (binomial distribution). The product is called the posterior. It's important to note, however, that there are some interesting facts you need to know about these two particular distributions. The product of a beta with parameters (alpha and beta) and a binomial, where we know that a player with accuracy P was seen scoring K kicks out of N, ends up being another beta distribution with parameters: ($\alpha_{new}&space;=&space;\alpha&space;+&space;K&space;%0$) and ($\beta_{new}&space;=&space;\beta&space;+&space;N&space;-&space;K&space;%0$). Because of the properties of these particular distributions, we call beta a conjugate prior. You can check the derivation in this video. The new beta distribution is now our posterior.
How can I speak about soccer nowadays without mentioning Lionel Messi and Cristiano Ronaldo? Let’s compare these two players’ penalty kick accuracy. It's always a good idea to validate your data, but for the sake of this example, I’ve found some information about these players on an obscure website. According to the website, Messi scored in 81 penalty kicks and missed 24 of them, while Ronaldo scored 109 and missed 23. Knowing these numbers, we can easily calculate and plot the posterior distributions of the two players and compare them.
# Python Imports
import numpy as np
import pandas as pd
from numpy.random import binomial
from numpy.random import beta
# Our priors Beta distribution parameters
prior_alpha = 1
prior_beta = 1
# How many kicks were scored
successes_messi = 81
successes_ronaldo = 109
# How many kicks were not scored
fails_messi = 24
fails_ronaldo = 23
# Calculate Posterior := Likelihood * Prior
messi_samples = beta(
a = prior_alpha + successes_messi,
b = prior_beta + fails_messi,
size=10000
)
ronaldo_samples = beta(
a = prior_alpha + successes_ronaldo,
b = prior_beta + fails_ronaldo,
size=10000
)
fig, ax = plt.subplots(1, 1, figsize=(12,8))
pd.DataFrame(
{
'Posterior Messi': messi_samples,
'Posterior Ronaldo': ronaldo_samples,
}
).plot(
kind='hist',
title='Messi vs Ronaldo Penalty Shootout Accuracy',
bins=100,
alpha=0.5,
ax=ax,
)
# Add lines to show the medians of each distribution
ax.vlines(
x=np.median(messi_samples), ymin=0, ymax=500, color='red', alpha=0.75,
)
ax.vlines(
x=np.median(ronaldo_samples), ymin=0, ymax=500, color='blue', alpha=0.75,
)
fig.show()
At this point, you might be wondering about the "size" of the parameter used and why I called the posterior a distribution. Imagine that we are able to clone people, and we made 10,000 clones each of Messi and Ronaldo; hence the size is set to 10,000. Each of these clones is generated from the aforementioned posterior beta distributions. What we are comparing now is the distributions of those 20,000 clones.
We can see that there is overlap between the two distributions, but what is more important is quantifying the difference between the distributions. Remember, we are now comparing one Messi clone to one Ronaldo clone at a time, and repeating this process for 10,000 clones. We want to figure out how often one clone is better than the other, and the distributions of those differences. Thus, we are going to subtract the two posterior samples from each other and plot the difference. We can also draw a vertical red line at zero; the probability mass to the right of red line represents how often in our samples Ronaldo is more accurate. Or in Bayesian terms, it represents our confidence in Ronaldo being more accurate. The black line is at the median of the distribution of the differences, as it shows the expected value of how accurate Ronaldo is compare to Messi.
# Calculate the difference between the two samples
samples_diff = pd.Series(ronaldo_samples) - pd.Series(messi_samples)
# Find the median of the difference
samples_diff_median = samples_diff.median()
fig, ax = plt.subplots(1, 1, figsize=(12,8))
# Plot the samples difference
samples_diff.plot(
kind='hist',
title='Diff (Ronaldo - Messi)',
bins=100,
color='Gray',
alpha=0.75,
ax=ax,
)
ax.set_xlabel("Expected Difference in Rates")
# Draw a black line at the median of the difference
diff_vline_min, diff_vline_max = ax.get_ylim()
ax.plot(
(samples_diff_median, samples_diff_median),
(diff_vline_min, diff_vline_max),
'Black',
alpha=0.5,
)
# Draw a red line at zero
ax.plot(
(0, 0),
(diff_vline_min, diff_vline_max),
'Red',
alpha=0.5,
)
fig.show()
There is a much bigger probability mass to the red line’s right, which shows more confidence in Ronaldo having better penalty shootout skills. We can quantify the difference between the two players’ accuracy and the confidence in that difference as follows:
print(
'Confidence that Ronaldo > Messi: {}%'.format(
(
100 * ((b_samples - a_samples) > 0).mean()
).round(2)
)
)
print(
'Difference (Ronaldo - Messi) Median {}%'.format(
round(100 * samples_diff_median, 2)
)
)
# Confidence that Ronaldo > Messi: 85.58%
# Difference (Ronaldo - Messi) Median 5.39%
The outcome of penalty kicks is binary; you either scored or didn't score. What about something like darts? You throw a dart and you can get a different score depending on where it hits the board. In a case like this one, our favorite beta and binomial distributions won’t work. Thankfully, there are two other distributions that are fit for this scenario: Categorical distribution is the equivalent of the binomial distribution and Dirichlet is the non-binary version of beta. And yes, you guessed it, the Dirichlet and categorical distributions are also conjugates. It's fairly easy to replace the code above with the new distributions and figure out how to parameterize the posterior Dirichlet distribution with the prior and likelihood parameters.
### Conclusion
It’s clear that bayesian analysis has its perks. It is easy and more informative than traditional p-values. You can actually see the difference between two treatments you are comparing — and you're able to quantify the confidence you have in this difference. You also can use a more informed prior if you want to include your prior belief in a certain outcome. There are plenty of Python libraries to help you calculate and plot your analysis. I used NumPy here, but PyMC3 is a good — and more advanced alternative.
As we have seen, the most important part of this work is to think clearly about what you are measuring and find the proper distributions to represent your prior knowledge and the likelihood of an event. We have touched on both binary and categorical events in this post, but I would be happy to hear from readers about different kind of events they test and what kind of distributions they find to be more suitable for them. Wikipedia has a helpful list of conjugate distributions you can look at for inspiration.
I wish you the best of luck analyzing your next experiment the Bayesian way!
Author
Tarek Amr
Tarek Amr is based in the Netherlands, where he works as a machine learning scientist. His book, Practical D3.js, provides step-by-step guidance to mastering the efficient use of D3.js in data visualization projects. Tarek is passionate about open data initiatives and is happy to respond to questions and comments on LinkedIn.
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https://facelessuser.github.io/pymdown-extensions/
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# PyMdown Extensions
## Usage
PyMdown Extensions is a collection of extensions for Python Markdown. Keep in mind, the PyMdown extensions were designed to work with the default extensions, so your mileage may vary in regards to compatibility when paired with other 3rd party extensions.
All extensions are found under pymdownx. Assuming we wanted to specify the use of the MagicLink extension, we would include it in Python Markdown like so:
>>> import markdown
Check out documentation on each extension to learn more about how to configure and use each one.
Reminder
Please read the Usage Notes for information on extension compatibility and general notes to be aware of when using these extensions.
## Extensions
Arithmatex
Arithmatex is an extension that preserves LaTeX math equations ($\frac{\sqrt x}{y^3}$) during the Markdown conversion process so that they can be used with MathJax.
B64
B64 converts all local images in a document to base64 encoding and embeds them in the document.
BetterEm
BetterEm is a different approach to emphasis than Python Markdown's default. It works similar but handles certain corner cases differently.
Caret
Caret is an extension that is syntactically built around the ^ character. It adds support for inserting superscripts and adds an easy way to place text in an <ins> tag.
Critic
Critic adds handling and support of Critic Markup.
Details
Details creates collapsible elements with <details><summary> tags.
Click Me!
Thanks!
Emoji
Emoji makes adding emoji via Markdown easy .
EscapeAll
EscapeAll allows the escaping of any character, some with additional effects. Check it out to learn more.
Extra
Extra is just like Python Markdown's Extra package except it uses PyMdown Extensions to substitute similar extensions.
ExtraRawHTML
ExtraRawHTML exposes Python Markdown's feature of parsing markdown in HTML blocks. No longer do you have to include all of Extra when all you want to do is parse Markdown in HTML blocks.
Highlight
Highlight allows you to configure the syntax highlighting of SuperFences and InlineHilite. Also passes standard Markdown indented code blocks through the syntax highlighter.
InlineHilite
InlineHilite highlights inline code: from module import function as func.
Keys
Keys makes inserting key inputs into documents as easy as pressing CtrlAltDel.
MagicLink linkafies URL and email links without having to wrap them in Markdown syntax. Also, allows shortens repository issue, pull request, and commit links. You can even use easily insert mentions: @twitter.
Mark
Mark allows you to mark words easily.
PathConverter
PathConverter converts paths to absolute or relative to a given base path.
ProgressBar
ProgressBar creates progress bars quick and easy.
SmartSymbols
SmartSymbols inserts commonly used Unicode characters via simple ASCII representations: =/= → ≠.
Snippets
Snippets include other Markdown or HTML snippets into the current Markdown file being parsed.
StripHTML
StripHTML can strip out HTML comments and specific tag attributes.
SuperFences
SuperFences is like Python Markdown's fences, but better. Nest fences under lists, admonitions, and other syntaxes. Combine multiple fences together in tabbed groups, and even create special custom fences for content like UML.
Title: Here is a title
A->B: Normal line
B-->C: Dashed line
C->>D: Open arrow
D-->>A: Dashed open arrow
Title: Here is a title
A->B: Normal line
B-->C: Dashed line
C->>D: Open arrow
D-->>A: Dashed open arrow
Tilde is syntactically built around the ~ character. It adds support for inserting subscripts and adds an easy way to place text in a <del> tag.
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http://hmf.enseeiht.fr/travaux/bei/beiep/content/2012-g16/droplets-distribution
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Droplets distribution
Establishment of a model for the water bombing from an aircraft
When a drop is too big, it gives birth to smaller droplets according to several breakup regimes, depending on the Weber number :
$We=\frac{aerodynamic force}{surface tension force}=\frac{\rho_G \| \vec{U_G}-\vec{V_p} \|^2 d_p}{\sigma}$
Breakup regimes
Another adimensional number plays a role in the atomization process : the Bond number
$Bo=\frac{gravity force}{surface tension force}=\frac{\rho_G g {d_p}^2}{\sigma}$
To remain stable, a droplet has to satisfy the following conditions :
• $We_{drop} \le We_{cr}$
• $Bo_{drop} \le Bo_{cr}$
When it does not, the drop - called the "mother" drop - gives birth to small droplets, called "children" droplets. To simplify the problem here, we chose to consider the division of the "mother" drop into two "children" droplets. The centre of mass C of the new-formed droplet will be randomly located on a sphere around the centre of mass M of the "mother" drop, the radius being equal to the mother drop's diameter :
Spherical coordinates
Our approach consisted in studying each droplet, evaluating its Weber and Bond numbers. Big at the beginning, all the drops are divided into smaller droplets, until the "children" droplets satisfy the stability criteria. Hence, at the end, the stable droplets are all the same size.
The droplets distribution is as below :
Droplets distribution right after the second atomization
The next step, now, is to calculate the movement equation of every single drop, in order to evaluate the mark on the ground.
|
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|
http://www.ni.com/documentation/en/labview-comms/1.0/mnode-ref/pi/
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Version:
Represents the value of pi (3.1415926535897...). pi is defined as the perimeter of a circle divided by its diameter.
## Syntax
c = pi
Value of pi.
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http://physics.stackexchange.com/questions/6630/could-a-bubble-of-photons-make-a-spaceship-massless?answertab=active
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# Could a bubble of photons make a spaceship massless? [closed]
I'm not sure how theoretically possible this is but my question is...
If we could somehow make a perfect bubble of photons (a massless bubble) and put a spaceship inside it, could it therefore effectively become massless as the perfectly sealed bubble around it has no mass adn therefore travel at lightspeed?
Sorry if this is just nonsense.
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## closed as off-topic by ACuriousMind, Kyle Kanos, Brandon Enright, John Rennie, DanuSep 27 '14 at 8:05
This question appears to be off-topic. The users who voted to close gave this specific reason:
• "We deal with mainstream physics here. Questions about the general correctness of unpublished personal theories are off topic, although specific questions evaluating new theories in the context of established science are usually allowed. For more information, see Is non mainstream physics appropriate for this site?." – Kyle Kanos, Brandon Enright, John Rennie, Danu
If this question can be reworded to fit the rules in the help center, please edit the question.
As my friend Zach once remarked when confronted with a similar question, "I've got a mushroom pound of photons for your forehead." I don't know what he meant, but it sure was snappy. Joking aside, I think the answer to this question is 'no'. The mass of an object is not generally related to the presence or absence of photons nearby. – Andrew Mar 10 '11 at 16:32
Let me enumerate several reasons why it's indeed nonsense:
1. Photons are called massless because their rest mass is zero; however, their total mass that is subject to gravity etc. is given by their energy, $E=mc^2=hf$, and it is nonzero
2. Photons can't be kept in a shell because they need to move by the speed of light; the closest thing you can get is the "photon orbit" of a black hole - at distance $R=3GM/c^2$ from a neutral black hole center, for example - where photons may move for a long time but this orbit is unstable, so the photons eventually either fall to the black hole or escape from it
3. Even if you ignored the problems above, the photons would have no impact on the spaceship inside: analogously, toilet paper is also light but a dumbbell doesn't become light just because you pack it in toilet paper. I have already written enough so if you need to explain why the previous sentence is true, please ask another question and someone else may wrestle with it.
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"but a dumbbell doesn't become light just because you pack it in toilet paper" lol, thank you! I think I understand now! Photons really do cause me problems getting my head around. But this has helped a lot. – takkischitt Mar 10 '11 at 16:40
It was a pleasure. Photons are cool but they're just pieces of light. – Luboš Motl Mar 10 '11 at 17:10
Funny for you to say that "Photons (...) [a]re just pieces of light". As Einstein said in a letter to Besso: "50 years of consciously pondering have not gotten me closer to the answer of the question 'What are quanta of light'. Today every rascal thinks he knows but he is wrong" (that's a simple translation from the originally german letter) – BandGap Mar 11 '11 at 10:55
The real answer here is 'why not?', of course!
You all assume that you need billions of static photons to form a bubble.
Just one, (obviously, traveling at the speed of light), and forced to follow an arc which steps sideways by the width of a photon on completion of one orbit, would be a complete bubble to us.
What forces are generated inside this one photon bubble? This is the question to ask yourselves.
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Jeez! I never looked at it from that point of view! – Terry the Timelord Mar 21 '13 at 19:44
Bit of a weird comment on your own post ;) – Bernhard Mar 21 '13 at 20:08
That's an answer fitting to the level of the question. Science fiction for non-physicians. ;) – Stefan Bischof Mar 21 '13 at 20:15
This is just nonsense.
The only remotely possible idea that comes to mind in this context is by using the photon's impulse to maintain some sort of balanced spaceship but there is no way to create a bubble of photons. They cannot be confined without some material border (aka mirror)and you would have to carry that weight with you.
Edit: Ok, not only material borders but also bending of space would allow for photon confinement. But gravitational effects have the side effect that you need some major amount of mass to do that (black holes, galaxy clusters, ...). Unfortunately to accelerate such a body you need a lot of force of some kind since F=ma and thus a=F/m. (a being acceleration, m the mass and F the force)
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Thanks for your answer. I'm not a physicist or in any way schooled in this sort of subject so this is more a product of my basic knowledge and imagination, so again, this may appear as nonsense... but gravity bends light (photons) as in the case with gravitational lensing, so would it be theoretically possible to hold the photons in a bubble through massive gravitational fields? – takkischitt Mar 10 '11 at 16:30
@takkischitt Read Lubos' answer again. You would need a black hole to bend the light a lot , but it would not form a bubble. – anna v Mar 10 '11 at 20:51
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https://en.wikipedia.org/wiki/Federated_database_system
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# Federated database system
A federated database system is a type of meta-database management system (DBMS), which transparently maps multiple autonomous database systems into a single federated database. The constituent databases are interconnected via a computer network and may be geographically decentralized. Since the constituent database systems remain autonomous, a federated database system is a contrastable alternative to the (sometimes daunting) task of merging several disparate databases. A federated database, or virtual database, is a composite of all constituent databases in a federated database system. There is no actual data integration in the constituent disparate databases as a result of data federation.
Through data abstraction, federated database systems can provide a uniform user interface, enabling users and clients to store and retrieve data from multiple noncontiguous databases with a single query—even if the constituent databases are heterogeneous. To this end, a federated database system must be able to decompose the query into subqueries for submission to the relevant constituent DBMSs, after which the system must composite the result sets of the subqueries. Because various database management systems employ different query languages, federated database systems can apply wrappers to the subqueries to translate them into the appropriate query languages.
## Definition
McLeod and Heimbigner[1] were among the first to define a federated database system in the mid 1980s.
A FDBS is one which "define[s] the architecture and interconnect[s] databases that minimize central authority yet support partial sharing and coordination among database systems".[1] This description might not accurately reflect the McLeod/Heimbigner[1] definition of a federated database. Rather, this description fits what McLeod/Heimbigner called a composite database. McLeod/Heimbigner's federated database is a collection of autonomous components that make their data available to other members of the federation through the publication of an export schema and access operations; there is no unified, central schema that encompasses the information available from the members of the federation.
Among other surveys,[2] practitioners define a Federated Database as a collection of cooperating component systems which are autonomous and are possibly heterogeneous.
The three important components of an FDBS are autonomy, heterogeneity and distribution.[2] Another dimension which has also been considered is the Networking Environment Computer Network, e.g., many DBSs over a LAN or many DBSs over a WAN update related functions of participating DBSs (e.g., no updates, nonatomic transitions, atomic updates).
## FDBS architecture
A DBMS can be classified as either centralized or distributed. A centralized system manages a single database while distributed manages multiple databases. A component DBS in a DBMS may be centralized or distributed. A multiple DBS (MDBS) can be classified into two types depending on the autonomy of the component DBS as federated and non federated. A nonfederated database system is an integration of component DBMS that are not autonomous. A federated database system consists of component DBS that are autonomous yet participate in a federation to allow partial and controlled sharing of their data.
Federated architectures differ based on levels of integration with the component database systems and the extent of services offered by the federation. A FDBS can be categorized as loosely or tightly coupled systems.
• Loosely Coupled require component databases to construct their own federated schema. A user will typically access other component database systems by using a multidatabase language but this removes any levels of location transparency, forcing the user to have direct knowledge of the federated schema. A user imports the data they require from other component databases and integrates it with their own to form a federated schema.
• Tightly coupled system consists of component systems that use independent processes to construct and publicize an integrated federated schema.
Multiple DBS of which FDBS are a specific type can be characterized along three dimensions: Distribution, Heterogeneity and Autonomy. Another characterization could be based on the dimension of networking, for example single databases or multiple databases in a LAN or WAN.
### Distribution
Distribution of data in an FDBS is due to the existence of a multiple DBS before an FDBS is built. Data can be distributed among multiple databases which could be stored in a single computer or multiple computers. These computers could be geographically located in different places but interconnected by a network. The benefits of data distribution help in increased availability and reliability as well as improved access times.
#### Heterogeneity
Heterogeneities in databases arise due to factors such as differences in structures, semantics of data, the constraints supported or query language. Differences in structure occur when two data models provide different primitives such as object oriented (OO) models that support specialization and inheritance and relational models that do not. Differences due to constraints occur when two models support two different constraints. For example, the set type in CODASYL schema may be partially modeled as a referential integrity constraint in a relationship schema. CODASYL supports insertion and retention that are not captured by referential integrity alone. The query language supported by one DBMS can also contribute to heterogeneity between other component DBMSs. For example, differences in query languages with the same data models or different versions of query languages could contribute to heterogeneity.
Semantic heterogeneities arise when there is a disagreement about meaning, interpretation or intended use of data. At the schema and data level, classification of possible heterogeneities include:
• Naming conflicts e.g. databases using different names to represent the same concept.
• Domain conflicts or data representation conflicts e.g. databases using different values to represent same concept.
• Precision conflicts e.g. databases using same data values from domains of different cardinalities for same data.
• Metadata conflicts e.g. same concepts are represented at schema level and instance level.
• Data conflicts e.g. missing attributes
• Schema conflicts e.g. table versus table conflict which includes naming conflicts, data conflicts etc.
In creating a federated schema, one has to resolve such heterogeneities before integrating the component DB schemas.
#### Schema matching, schema mapping
Dealing with incompatible data types or query syntax is not the only obstacle to a concrete implementation of an FDBS. In systems that are not planned top-down, a generic problem lies in matching semantically equivalent, but differently named parts from different schemas (=data models) (tables, attributes). A pairwise mapping between n attributes would result in ${\displaystyle n(n-1) \over 2}$ mapping rules (given equivalence mappings) - a number that quickly gets too large for practical purposes. A common way out is to provide a global schema that comprises the relevant parts of all member schemas and provide mappings in the form of database views. Two principal approaches depend on the direction of the mapping:
1. Global as View (GaV): the global schema is defined in terms of the underlying schemas
2. Local as View (LaV): the local schemas are defined in terms of the global schema
Both are examples of data integration, called the schema matching problem.
### Autonomy
Fundamental to the difference between an MDBS and an FDBS is the concept of autonomy. It is important to understand the aspects of autonomy for component databases and how they can be addressed when a component DBS participates in an FDBS. There are four kinds of autonomies addressed:
• Design Autonomy which refers to ability to choose its design irrespective of data, query language or conceptualization, functionality of the system implementation.
Heterogeneities in an FDBS are primarily due to design autonomy.
• Communication autonomy refers to the general operation of the DBMS to communicate with other DBMS or not.
• Execution autonomy allows a component DBMS to control the operations requested by local and external operations.
• Association autonomy gives a power to component DBS to disassociate itself from a federation which means FDBS can operate independently of any single DBS.
The ANSI/X3/SPARC Study Group outlined a three level data description architecture, the components of which are the conceptual schema, internal schema and external schema of databases. The three level architecture is however inadequate to describing the architectures of an FDBS. It was therefore extended to support the three dimensions of the FDBS namely Distribution, Autonomy and Heterogeneity. The five level schema architecture is explained below.
### Concurrency control
The Heterogeneity and Autonomy requirements pose special challenges concerning concurrency control in an FDBS, which is crucial for the correct execution of its concurrent transactions (see also Global concurrency control). Achieving global serializability, the major correctness criterion, under these requirements has been characterized as very difficult and unsolved.[2] Commitment ordering, introduced in 1991, has provided a general solution for this issue (See Global serializability; See Commitment ordering also for the architectural aspects of the solution).
## Five Level Schema Architecture for FDBSs
The five level schema architecture includes the following:
• Local Schema is basically the conceptual model of a component database expressed in a native data model.[3]
• Component schema is the subset of the local schema that the owner organisation is willing to share with other users of the FDBS and it is translated into a common data model.[3]
• Export Schema represents a subset of a component schema that is available to a particular federation.[3] It may include access control information regarding its use by a specific federation user. The export schema helps in managing flow of control of data.
• Federated Schema is an integration of multiple export schemas. It includes information on data distribution that is generated when integrating export schemas.[3]
• External schema is extracted from a federated schema, and is defined for the users/applications of a particular federation.[3]
While accurately representing the state of the art in data integration, the Five Level Schema Architecture above does suffer from a major drawback, namely IT imposed look and feel. Modern data users demand control over how data is presented; their needs are somewhat in conflict with such bottom-up approaches to data integration.
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https://digitalslidearchive.github.io/HistomicsTK/examples/annotations_to_object_segmentation_masks.html
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# Converting annotations to object segmentation mask images¶
Overview:
The DSA database stores annotations in an (x,y) coordinate list format. Some object localization algorithms like Faster-RCNN take coordinate formats whereas others (eg Mask R-CNN) require some form of object segmentation mask image whose pixel values encode not only class but instance information (so that individual objects of the same class can be distinguished).
This notebook demonstrates tools to convert annotations into contours or masks that can be used with algorithms like Mask-RCNN. There are two approaches for generating these data:
• Generate contours or an object segmentation mask image from a region defined by user-specified coordinates.
• Generate contours or object segmentation mask images from annotations contained within region-of-interest (ROI) annotations. This involves mapping annotations to these ROIs and creating one image per ROI.
The examples below extend approaches described in Amgad et al, 2019:
Mohamed Amgad, Habiba Elfandy, Hagar Hussein, …, Jonathan Beezley, Deepak R Chittajallu, David Manthey, David A Gutman, Lee A D Cooper, Structured crowdsourcing enables convolutional segmentation of histology images, Bioinformatics, , btz083, https://doi.org/10.1093/bioinformatics/btz083
A csv file like the one in histomicstk/annotations_and_masks/tests/test_files/sample_GTcodes.csv is needed to define what group each pixel value corresponds to in the mask image, to define the overlay order of various annotation groups, and which groups are considered to be ROIs. Note that the term “group” here comes from the annotation model where each group represents a class like “tumor” or “necrosis” and is associated with a an annotation style.
What is the difference between this and annotations_to_masks_handler?
The difference between this and version 1, found at histomicstk.annotations_and_masks.annotations_to_masks_handler is that this (version 2) gets the contours first, including cropping to wanted ROI boundaries and other processing using shapely, and then parses these into masks. This enables us to differentiate various objects to use the data for object localization/classification/segmentation tasks. If you would like to get semantic segmentation masks instead, i.e. you do not care about individual objects, you can use either version 1 or this handler using the semantic run mode. They re-use much of the same code-base, but some edge cases maybe better handled by version 1. For example, since this version uses shapely first to crop, some objects may be incorrectly parsed by shapely. Version 1, using PIL.ImageDraw may not have these problems.
Bottom line is: if you need semantic segmentation masks, it is probably safer to use version 1 (annotations to masks handler), whereas if you need object segmentation masks, this handler should be used in object run mode.
Where to look?
|_ histomicstk/
|_tests/
[1]:
import os
import copy
import girder_client
import tempfile
import matplotlib.pyplot as plt
%matplotlib inline
get_bboxes_from_slide_annotations,
scale_slide_annotations, get_scale_factor_and_appendStr)
get_all_rois_from_slide_v2)
#Some nice default configuration for plots
plt.rcParams['figure.figsize'] = 7, 7
titlesize = 16
## Connect girder client and set parameters¶
[2]:
CWD = os.getcwd()
APIURL = 'http://candygram.neurology.emory.edu:8080/api/v1/'
SAMPLE_SLIDE_ID = '5d586d57bd4404c6b1f28640'
GTCODE_PATH = os.path.join(CWD, '../../tests/test_files/sample_GTcodes.csv')
# connect to girder client
gc = girder_client.GirderClient(apiUrl=APIURL)
# gc.authenticate(interactive=True)
# just a temp directory to save masks for now
BASE_SAVEPATH = tempfile.mkdtemp()
SAVEPATHS = {
'rgb': os.path.join(BASE_SAVEPATH, 'rgbs'),
'contours': os.path.join(BASE_SAVEPATH, 'contours'),
'visualization': os.path.join(BASE_SAVEPATH, 'vis'),
}
for _, savepath in SAVEPATHS.items():
os.mkdir(savepath)
# What resolution do we want to get the images at?
# Microns-per-pixel / Magnification (either or)
MPP = 2.5 # <- this roughly translates to 4x magnification
MAG = None
### Let’s inspect the ground truth codes file¶
This contains the ground truth codes and information dataframe. This is a dataframe that is indexed by the annotation group name and has the following columns:
• group: group name of annotation (string), eg. “mostly_tumor”
• overlay_order: int, how early to place the annotation in the mask. Larger values means this annotation group is overlayed last and overwrites whatever overlaps it.
• GT_code: int, desired ground truth code (in the labeled mask) Pixels of this value belong to corresponding group (class)
• is_roi: Flag for whether this group marks ‘special’ annotations that encode the ROI boundary
• is_background_class: Flag, whether this group is the default fill value inside the ROI. For example, you may descide that any pixel inside the ROI is considered stroma.
NOTE:
Zero pixels have special meaning and do not encode specific ground truth class. Instead, they simply mean ‘Outside ROI’ and should be ignored during model training or evaluation.
[3]:
# read GTCodes file
GTCodes_dict.index = GTCodes_dict.loc[:, 'group']
GTCodes_dict = GTCodes_dict.to_dict(orient='index')
[4]:
GTCodes_dict.keys()
[4]:
dict_keys(['roi', 'evaluation_roi', 'mostly_tumor', 'mostly_stroma', 'mostly_lymphocytic_infiltrate', 'necrosis_or_debris', 'glandular_secretions', 'mostly_blood', 'exclude', 'metaplasia_NOS', 'mostly_fat', 'mostly_plasma_cells', 'other_immune_infiltrate', 'mostly_mucoid_material', 'normal_acinus_or_duct', 'lymphatics', 'undetermined', 'nerve', 'skin_adnexia', 'blood_vessel', 'angioinvasion', 'mostly_dcis', 'other'])
[5]:
GTCodes_dict['mostly_tumor']
[5]:
{'group': 'mostly_tumor',
'overlay_order': 1,
'GT_code': 1,
'is_roi': 0,
'is_background_class': 0,
'color': 'rgb(255,0,0)',
## Generate contours for user-defined region¶
Algorithms like Mask-RCNN consume coordinate data describing the boundaries of objects. The function annotations_to_contours_no_mask generates this countour data for user-specified region. These coordinate data in these contours is relative to the region frame instead of the whole-slide image frame.
[6]:
print(annotations_to_contours_no_mask.__doc__)
Process annotations to get RGB and contours without intermediate masks.
Parameters
----------
gc : object
girder client object to make requests, for example:
gc = girder_client.GirderClient(apiUrl = APIURL)
gc.authenticate(interactive=True)
slide_id : str
girder id for item (slide)
MPP : float or None
Microns-per-pixel -- best use this as it's more well-defined than
magnification which is more scanner or manufacturer specific.
MPP of 0.25 often roughly translates to 40x
MAG : float or None
If you prefer to use whatever magnification is reported in slide.
If neither MPP or MAG is provided, everything is retrieved without
scaling at base (scan) magnification.
mode : str
This specifies which part of the slide to get the mask from. Allowed
modes include the following
- wsi: get scaled up or down version of mask of whole slide
- min_bounding_box: get minimum box for all annotations in slide
- manual_bounds: use given ROI bounds provided by the 'bounds' param
- polygonal_bounds: use the idx_for_roi param to get coordinates
bounds : dict or None
if not None, has keys 'XMIN', 'XMAX', 'YMIN', 'YMAX' for slide
region coordinates (AT BASE MAGNIFICATION) to get labeled image
(mask) for. Use this with the 'manual_bounds' run mode.
idx_for_roi : int
index of ROI within the element_infos dataframe.
Use this with the 'polygonal_bounds' run mode.
slide_annotations : list or None
Give this parameter to avoid re-getting slide annotations. If you do
provide the annotations, though, make sure you have used
scale_slide_annotations() to scale them up or down by sf BEFOREHAND.
element_infos : pandas DataFrame.
The columns annidx and elementidx
encode the dict index of annotation document and element,
respectively, in the original slide_annotations list of dictionaries.
This can be obained by get_bboxes_from_slide_annotations() method.
Make sure you have used scale_slide_annotations().
linewidth : float
visualization line width
get_rgb: bool
get rgb image?
get_visualization : bool
get overlayed annotation bounds over RGB for visualization
text : bool
Returns
--------
dict
Results dict containing one or more of the following keys
- bounds: dict of bounds at scan magnification
- rgb: (mxnx3 np array) corresponding rgb image
- contours: dict
- visualization: (mxnx3 np array) visualization overlay
### More input parameters¶
These optional parameters describe the desired magnification or resolution of the output, and whether to generate an RGB image for the region and a visualization image of the annotations.
[7]:
# common params for annotations_to_contours_no_mask()
annotations_to_contours_kwargs = {
'MPP': MPP, 'MAG': MAG,
'linewidth': 0.2,
'get_rgb': True,
'get_visualization': True,
'text': False,
}
### 1. manual_bounds mode¶
As shown in the example for generating semantic segmentation masks, this method can be run in four run modes: 1. wsi 2. min_bounding_box 3. manual_bounds 4. polygonal_bounds. Here we test the basic ‘manual_bounds’ mode where the boundaries of the region you want are provided at base/scan magnification.
[8]:
bounds = {
'XMIN': 58000, 'XMAX': 63000,
'YMIN': 35000, 'YMAX': 39000
}
[9]:
# get specified region, let the method get and scale annotations
gc=gc, slide_id=SAMPLE_SLIDE_ID,
mode='manual_bounds', bounds=bounds,
**annotations_to_contours_kwargs)
/home/mtageld/Desktop/HistomicsTK/histomicstk/annotations_and_masks/annotation_and_mask_utils.py:668: RuntimeWarning: invalid value encountered in greater
iou = iou[:, iou[1, :] > iou_thresh].astype(int)
The result is an rgb image, contours and a visualization. Let’s take a look at these below.
[10]:
roi_out.keys()
[10]:
dict_keys(['rgb', 'contours', 'bounds', 'visualization'])
[11]:
roi_out['bounds']
[11]:
{'XMIN': 57994, 'XMAX': 62994, 'YMIN': 34999, 'YMAX': 38992}
[12]:
for imstr in ['rgb', 'visualization']:
plt.imshow(roi_out[imstr])
plt.title(imstr)
plt.show()
[13]:
DataFrame(roi_out['contours']).head()
[13]:
annidx annotation_girder_id elementidx element_girder_id type group label color xmin xmax ymin ymax bbox_area coords_x coords_y
0 0 5d586d58bd4404c6b1f28642 0 5a943eb992ca9a0016fae97f rectangle roi roi rgb(163, 19, 186) 121 501 0 310 117800 491,143,121,292,501,501,491 0,0,13,310,189,15,0
1 1 5d586d58bd4404c6b1f28644 0 5a943eb992ca9a0016fae981 polyline blood_vessel blood_vessel rgb(128,0,128) 341 360 241 259 342 353,352,351,350,350,349,348,347,346,345,344,34... 241,241,241,241,242,242,242,242,242,242,242,24...
2 1 5d586d58bd4404c6b1f28644 1 5a943eb992ca9a0016fae982 polyline blood_vessel blood_vessel rgb(128,0,128) 244 258 161 181 280 244,244,244,244,244,244,245,245,245,245,245,24... 161,162,163,165,166,167,167,168,169,170,171,17...
3 2 5d586d58bd4404c6b1f2864c 0 5a943eba92ca9a0016fae990 polyline mostly_lymphocytic_infiltrate mostly_lymphocytic_infiltrate rgb(0,0,255) 388 501 71 236 18645 501,501,500,500,499,498,498,497,496,495,495,49... 171,75,75,74,74,74,73,73,72,72,71,71,71,71,72,...
4 2 5d586d58bd4404c6b1f2864c 1 5a943eba92ca9a0016fae994 polyline mostly_lymphocytic_infiltrate mostly_lymphocytic_infiltrate rgb(0,0,255) 359 434 0 21 1575 434,359,359,359,360,360,360,361,361,362,362,36... 0,0,1,2,2,3,4,5,6,6,7,7,7,7,7,8,8,8,9,9,11,12,...
Note that if the above function call is made repeatedly for the same slide (e.g. to iterate over multiple regions), multiple get requests would be created to retrieve annotations from the server. To improve efficiency when handling multiple regions in the same slide, we could manually get annotations and scale them down/up to desired resolution, and pass them to annotations_to_contours_no_mask().
[14]:
# get annotations for slide
slide_annotations = gc.get('/annotation/item/' + SAMPLE_SLIDE_ID)
# scale up/down annotations by a factor
sf, _ = get_scale_factor_and_appendStr(
gc=gc, slide_id=SAMPLE_SLIDE_ID, MPP=MPP, MAG=MAG)
slide_annotations = scale_slide_annotations(slide_annotations, sf=sf)
# get bounding box information for all annotations
element_infos = get_bboxes_from_slide_annotations(slide_annotations)
[15]:
# get specified region -- manually providing scaled annotations
gc=gc, slide_id=SAMPLE_SLIDE_ID,
mode='manual_bounds', bounds=bounds,
slide_annotations=slide_annotations, element_infos=element_infos,
**annotations_to_contours_kwargs)
/home/mtageld/Desktop/HistomicsTK/histomicstk/annotations_and_masks/annotation_and_mask_utils.py:668: RuntimeWarning: invalid value encountered in greater
iou = iou[:, iou[1, :] > iou_thresh].astype(int)
[16]:
roi_out['bounds']
[16]:
{'XMIN': 57994, 'XMAX': 62994, 'YMIN': 34999, 'YMAX': 38992}
### 2. min_bounding_box mode¶
In min_bounding_box mode everything in the slide is handled using the smallest rectangular bounding box.
[17]:
# get ROI bounding everything
gc=gc, slide_id=SAMPLE_SLIDE_ID,
mode='min_bounding_box', **annotations_to_contours_kwargs)
[18]:
minbbox_out['bounds']
[18]:
{'XMIN': 56726, 'YMIN': 33483, 'XMAX': 63732, 'YMAX': 39890}
[19]:
plt.imshow(minbbox_out['visualization'])
[19]:
<matplotlib.image.AxesImage at 0x7f1825c3f8d0>
### 3. wsi mode¶
wsi mode creates a scaled version of the entire whole-slide image and all annotations contained within.
NOTE:
This does not rely on tiles and processes the image at whatever magnification you want. You can supress the RGB or visualization outputs and to just fetch the contours or object segmentation mask (see below), providing a bigger magnification range before encountering memory problems.
[20]:
# get entire wsi region
get_kwargs = copy.deepcopy(annotations_to_contours_kwargs)
get_kwargs['MPP'] = 5.0 # otherwise it's too large!
gc=gc, slide_id=SAMPLE_SLIDE_ID,
mode='wsi', **get_kwargs)
[21]:
wsi_out['bounds']
[21]:
{'XMIN': 0, 'XMAX': 131516, 'YMIN': 0, 'YMAX': 80439}
[22]:
plt.imshow(wsi_out['visualization'])
plt.show()
[23]:
plt.imshow(wsi_out['visualization'][1500:2000, 2800:3300])
plt.show()
## Parse manually-drawn ROIs into separate labeled object masks¶
This function utilizes the polygonal_bounds mode of the get_image_and_mask_from_slide() method to generate a set of outputs for each ROI annotation.
In the example above we focused on generating contour data to represent objects. Below we focus on generating object segmentation mask images.
[24]:
print(get_all_rois_from_slide_v2.__doc__)
Get all ROIs for a slide without an intermediate mask form.
This mainly relies on contours_to_labeled_object_mask(), which should
be referred to for extra documentation.
This can be run in either the "object" mode, whereby the saved masks
are a three-channel png where first channel encodes class label (i.e.
same as semantic segmentation) and the product of the values in the
second and third channel encodes the object ID. Otherwise, the user
may decide to run in the "semantic" mode and the resultant mask would
consist of only one channel (semantic segmentation with no object
differentiation).
The difference between this and version 1, found at
get_all_rois_from_slide()
is that this (version 2) gets the contours first, including cropping
to wanted ROI boundaries and other processing using shapely, and THEN
parses these into masks. This enables us to differentiate various objects
to use the data for object localization or classification or segmentation
tasks. If you would like to get semantic segmentation masks, i.e. you do
not really care about individual objects, you can use either version 1
or this method. They re-use much of the same code-base, but some edge
cases maybe better handled by version 1. For example, since
this version uses shapely first to crop, some objects may be incorrectly
parsed by shapely. Version 1, using PIL.ImageDraw may not have these
problems.
Bottom line is: if you need semantic segmentation masks, it is probably
safer to use version 1, whereas if you need object segmentation masks,
this method should be used.
Parameters
----------
gc : object
girder client object to make requests, for example:
gc = girder_client.GirderClient(apiUrl = APIURL)
gc.authenticate(interactive=True)
slide_id : str
girder id for item (slide)
GTCodes_dict : dict
the ground truth codes and information dict.
This is a dict that is indexed by the annotation group name and
each entry is in turn a dict with the following keys:
- group: group name of annotation (string), eg. mostly_tumor
- overlay_order: int, how early to place the annotation in the
mask. Larger values means this annotation group is overlayed
last and overwrites whatever overlaps it.
- GT_code: int, desired ground truth code (in the mask)
Pixels of this value belong to corresponding group (class)
- is_roi: Flag for whether this group encodes an ROI
- is_background_class: Flag, whether this group is the default
fill value inside the ROI. For example, you may descide that
any pixel inside the ROI is considered stroma.
save_directories : dict
paths to directories to save data. Each entry is a string, and the
following keys are allowed
- ROI: path to save masks (labeled images)
- rgb: path to save rgb images
- contours: path to save annotation contours
- visualization: path to save rgb visualzation overlays
mode : str
run mode for getting masks. Must me in
- object: get 3-channel mask where first channel encodes label
(tumor, stroma, etc) while product of second and third
channel encodes the object ID (i.e. individual contours)
This is useful for object localization and segmentation tasks.
- semantic: get a 1-channel mask corresponding to the first channel
of the object mode.
While the main purpose of this method IS to get object segmentation
masks, it is conceivable that some users might just want to get
the RGB and contours. Default is True.
annotations_to_contours_kwargs : dict
default values are assigned if specific parameters are not given.
slide_name : str or None
If not given, its inferred using a server request using girder client.
verbose : bool
Print progress to screen?
monitorprefix : str
text to prepend to printed statements
callback : function
a callback function to run on the roi dictionary output. This is
internal, but if you really want to use this, make sure the callback
can accept the following keys and that you do NOT assign them yourself
gc, slide_id, slide_name, MPP, MAG, verbose, monitorprefix
Also, this callback MUST *ONLY* return thr roi dictionary, whether
or not it is modified inside it. If it is modified inside the callback
then the modified version is the one that will be saved to disk.
callback_kwargs : dict
kwargs to pass to callback, not including the mandatory kwargs
that will be passed internally (mentioned earlier here).
Returns
--------
list of dicts
each entry contains the following keys
rgb - path to saved rgb image
contours - path to saved annotation contours
visualization - path to saved rgb visualzation overlay
The above method mainly relies on contours_to_labeled_object_mask(), described below.
[25]:
print(contours_to_labeled_object_mask.__doc__)
Process contours to get and object segmentation labeled mask.
Parameters
----------
contours : DataFrame
contours corresponding to annotation elemeents from the slide.
All coordinates are relative to the mask that you want to output.
The following columns are expected.
- group: str, annotation group (ground truth label).
- ymin: int, minimun y coordinate
- ymax: int, maximum y coordinate
- xmin: int, minimum x coordinate
- xmax: int, maximum x coordinate
- coords_x: str, vertix x coordinates comma-separated values
- coords_y: str, vertix y coordinated comma-separated values
gtcodes : DataFrame
the ground truth codes and information dataframe.
This is a dataframe that is indexed by the annotation group name
and has the following columns.
- group: str, group name of annotation, eg. mostly_tumor.
- GT_code: int, desired ground truth code (in the mask).
Pixels of this value belong to corresponding group (class).
- color: str, rgb format. eg. rgb(255,0,0).
mode : str
run mode for getting masks. Must be in
- object: get 3-channel mask where first channel encodes label
(tumor, stroma, etc) while product of second and third
channel encodes the object ID (i.e. individual contours)
This is useful for object localization and segmentation tasks.
- semantic: get a 1-channel mask corresponding to the first channel
of the object mode.
verbose : bool
print to screen?
monitorprefix : str
prefix to add to printed statemens
Returns
-------
np.array
If mode is "object", this returns an (m, n, 3) np array
that can be saved as a png
First channel: encodes label (can be used for semantic segmentation)
Second & third channels: multiplication of second and third channel
gives the object id (255 choose 2 = 32,385 max unique objects).
This allows us to save into a convenient 3-channel png object labels
mask-rcnn save formats like having one channel per object and a
separate csv file for object labels. This is also more convenient
than simply saving things into pickled np array objects, and allows
If mode is "semantic" only the labels (corresponding to first
channel of the object mode) is output.
[26]:
get_all_rois_kwargs = {
'gc': gc,
'slide_id': SAMPLE_SLIDE_ID,
'GTCodes_dict': GTCodes_dict,
'save_directories': SAVEPATHS,
'annotations_to_contours_kwargs': annotations_to_contours_kwargs,
'slide_name': 'TCGA-A2-A0YE',
'mode': 'object',
'verbose': True,
'monitorprefix': 'test',
}
savenames = get_all_rois_from_slide_v2(**get_all_rois_kwargs)
test: roi 1 of 3: Overlay level -1: Element 1 of 50: roi
test: roi 1 of 3: Overlay level 1: Element 2 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 3 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 4 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 5 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 6 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 7 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 8 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 9 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 10 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 11 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 12 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 13 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 14 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 15 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 16 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 17 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 18 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 19 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 20 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 21 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 22 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 23 of 50: normal_acinus_or_duct
test: roi 1 of 3: Overlay level 1: Element 24 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 25 of 50: normal_acinus_or_duct
test: roi 1 of 3: Overlay level 1: Element 26 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 27 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 28 of 50: blood_vessel
test: roi 1 of 3: Overlay level 1: Element 29 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 30 of 50: blood_vessel
test: roi 1 of 3: Overlay level 1: Element 31 of 50: blood_vessel
test: roi 1 of 3: Overlay level 1: Element 32 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 33 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 34 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 35 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 36 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 37 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 38 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 39 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 40 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 41 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 42 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 43 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 44 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 45 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 1: Element 46 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 47 of 50: mostly_lymphocytic_infiltrate
test: roi 1 of 3: Overlay level 1: Element 48 of 50: mostly_tumor
test: roi 1 of 3: Overlay level 2: Element 49 of 50: mostly_stroma
test: roi 1 of 3: Overlay level 3: Element 50 of 50: exclude
test: roi 1 of 3: Saving /tmp/tmpvdwsnssq/masks/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png
test: roi 1 of 3: Saving /tmp/tmpvdwsnssq/rgbs/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png
test: roi 1 of 3: Saving /tmp/tmpvdwsnssq/vis/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png
test: roi 1 of 3: Saving /tmp/tmpvdwsnssq/contours/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.csv
test: roi 2 of 3: Overlay level -2: Element 1 of 16: roi
test: roi 2 of 3: Overlay level 1: Element 2 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 3 of 16: mostly_lymphocytic_infiltrate
test: roi 2 of 3: Overlay level 1: Element 4 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 5 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 6 of 16: mostly_lymphocytic_infiltrate
test: roi 2 of 3: Overlay level 1: Element 7 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 8 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 9 of 16: blood_vessel
test: roi 2 of 3: Overlay level 1: Element 10 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 11 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 1: Element 12 of 16: mostly_tumor
test: roi 2 of 3: Overlay level 2: Element 13 of 16: mostly_stroma
test: roi 2 of 3: Overlay level 2: Element 14 of 16: mostly_stroma
test: roi 2 of 3: Overlay level 2: Element 15 of 16: mostly_stroma
test: roi 2 of 3: Overlay level 3: Element 16 of 16: exclude
test: roi 2 of 3: Saving /tmp/tmpvdwsnssq/masks/TCGA-A2-A0YE_left-58473_top-38203_bottom-39780_right-60389.png
test: roi 2 of 3: Saving /tmp/tmpvdwsnssq/rgbs/TCGA-A2-A0YE_left-58473_top-38203_bottom-39780_right-60389.png
test: roi 2 of 3: Saving /tmp/tmpvdwsnssq/vis/TCGA-A2-A0YE_left-58473_top-38203_bottom-39780_right-60389.png
test: roi 2 of 3: Saving /tmp/tmpvdwsnssq/contours/TCGA-A2-A0YE_left-58473_top-38203_bottom-39780_right-60389.csv
test: roi 3 of 3: Overlay level -3: Element 1 of 11: roi
test: roi 3 of 3: Overlay level 1: Element 2 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 1: Element 3 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 1: Element 4 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 1: Element 5 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 1: Element 6 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 1: Element 7 of 11: mostly_tumor
test: roi 3 of 3: Overlay level 3: Element 8 of 11: exclude
test: roi 3 of 3: Overlay level 3: Element 9 of 11: exclude
test: roi 3 of 3: Overlay level 3: Element 10 of 11: exclude
test: roi 3 of 3: Overlay level 3: Element 11 of 11: exclude
test: roi 3 of 3: Saving /tmp/tmpvdwsnssq/masks/TCGA-A2-A0YE_left-57594_top-35808_bottom-37445_right-59441.png
test: roi 3 of 3: Saving /tmp/tmpvdwsnssq/rgbs/TCGA-A2-A0YE_left-57594_top-35808_bottom-37445_right-59441.png
test: roi 3 of 3: Saving /tmp/tmpvdwsnssq/vis/TCGA-A2-A0YE_left-57594_top-35808_bottom-37445_right-59441.png
test: roi 3 of 3: Saving /tmp/tmpvdwsnssq/contours/TCGA-A2-A0YE_left-57594_top-35808_bottom-37445_right-59441.csv
[27]:
savenames[0]
[27]:
{'mask': '/tmp/tmpvdwsnssq/masks/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png',
'rgb': '/tmp/tmpvdwsnssq/rgbs/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png',
'visualization': '/tmp/tmpvdwsnssq/vis/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.png',
'contours': '/tmp/tmpvdwsnssq/contours/TCGA-A2-A0YE_left-59191_top-33483_bottom-38083_right-63732.csv'}
### Let’s visualize the contours¶
[28]:
# visualization of contours over RGBs
for savename in savenames:
plt.imshow(vis)
plt.title(os.path.basename(savename["visualization"]))
plt.show()
### Let’s visualize the object mask¶
An object segmentation mask image uses the multiple channels to encode both class and instance information. In this mask format we multiply the second and third channel values to calculate a unique id for each object.
[29]:
mask = imread(savename["mask"])
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http://careyoukeep.com/most-effective-brain-enhancer-best-memory-support-supplement.html
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Cognition is a suite of mental phenomena that includes memory, attention and executive functions, and any drug would have to enhance executive functions to be considered truly ‘smart’. Executive functions occupy the higher levels of thought: reasoning, planning, directing attention to information that is relevant (and away from stimuli that aren’t), and thinking about what to do rather than acting on impulse or instinct. You activate executive functions when you tell yourself to count to 10 instead of saying something you may regret. They are what we use to make our actions moral and what we think of when we think about what makes us human.
My predictions were substantially better than random chance7, so my default belief - that Adderall does affect me and (mostly) for the better - is borne out. I usually sleep very well and 3 separate incidents of horrible sleep in a few weeks seems rather unlikely (though I didn’t keep track of dates carefully enough to link the Zeo data with the Adderall data). Between the price and the sleep disturbances, I don’t think Adderall is personally worthwhile.
# A Romanian psychologist and chemist named Corneliu Giurgea started using the word nootropic in the 1970s to refer to substances that improve brain function, but humans have always gravitated toward foods and chemicals that make us feel sharper, quicker, happier, and more content. Our brains use about 20 percent of our energy when our bodies are at rest (compared with 8 percent for apes), according to National Geographic, so our thinking ability is directly affected by the calories we’re taking in as well as by the nutrients in the foods we eat. Here are the nootropics we don’t even realize we’re using, and an expert take on how they work.
###### So what’s the catch? Well, it’s potentially addictive for one. Anything that messes with your dopamine levels can be. And Patel says there are few long-term studies on it yet, so we don’t know how it will affect your brain chemistry down the road, or after prolonged, regular use. Also, you can’t get it very easily, or legally for that matter, if you live in the U.S. It’s classified as a schedule IV controlled substance. That’s where Adrafinil comes in.
In fact, some of these so-called “smart drugs” are already remarkably popular. One recent survey involving tens of thousands of people found that 30% of Americans who responded had taken them in the last year. It seems as though we may soon all be partaking – and it’s easy to get carried away with the consequences. Will this new batch of intellectual giants lead to dazzling, space-age inventions? Or perhaps an explosion in economic growth? Might the working week become shorter, as people become more efficient?
My predictions were substantially better than random chance7, so my default belief - that Adderall does affect me and (mostly) for the better - is borne out. I usually sleep very well and 3 separate incidents of horrible sleep in a few weeks seems rather unlikely (though I didn’t keep track of dates carefully enough to link the Zeo data with the Adderall data). Between the price and the sleep disturbances, I don’t think Adderall is personally worthwhile.
With this experiment, I broke from the previous methodology, taking the remaining and final half Nuvigil at midnight. I am behind on work and could use a full night to catch up. By 8 AM, I am as usual impressed by the Nuvigil - with Modalert or something, I generally start to feel down by mid-morning, but with Nuvigil, I feel pretty much as I did at 1 AM. Sleep: 9:51/9:15/8:27
At this point, I began thinking about what I was doing. Black-market Adderall is fairly expensive; $4-10 a pill vs prescription prices which run more like$60 for 120 20mg pills. It would be a bad idea to become a fan without being quite sure that it is delivering bang for the buck. Now, why the piracetam mix as the placebo as opposed to my other available powder, creatine powder, which has much smaller mental effects? Because the question for me is not whether the Adderall works (I am quite sure that the amphetamines have effects!) but whether it works better for me than my cheap legal standbys (piracetam & caffeine)? (Does Adderall have marginal advantage for me?) Hence, I want to know whether Adderall is better than my piracetam mix. People frequently underestimate the power of placebo effects, so it’s worth testing. (Unfortunately, it seems that there is experimental evidence that people on Adderall know they are on Adderall and also believe they have improved performance, when they do not5. So the blind testing does not buy me as much as it could.)
That is, perhaps light of the right wavelength can indeed save the brain some energy by making it easier to generate ATP. Would 15 minutes of LLLT create enough ATP to make any meaningful difference, which could possibly cause the claimed benefits? The problem here is like that of the famous blood-glucose theory of willpower - while the brain does indeed use up more glucose while active, high activity uses up very small quantities of glucose/energy which doesn’t seem like enough to justify a mental mechanism like weak willpower.↩
Cognition is a suite of mental phenomena that includes memory, attention and executive functions, and any drug would have to enhance executive functions to be considered truly ‘smart’. Executive functions occupy the higher levels of thought: reasoning, planning, directing attention to information that is relevant (and away from stimuli that aren’t), and thinking about what to do rather than acting on impulse or instinct. You activate executive functions when you tell yourself to count to 10 instead of saying something you may regret. They are what we use to make our actions moral and what we think of when we think about what makes us human.
Many people prefer the privacy and convenience of ordering brain boosting supplements online and having them delivered right to the front door. At Smart Pill Guide, we have made the process easier, so you can place your order directly through our website with your major credit card or PayPal. Our website is secure, so your personal information is protected and all orders are completely confidential.
Fortunately, there are some performance-enhancing habits that have held up under rigorous scientific scrutiny. They are free, and easy to pronounce. Unfortunately, they are also the habits you were perhaps hoping to forego by using nootropics instead. “Of all the things that are supposed to be ‘good for the brain,’” says Stanford neurology professor Sharon Sha, “there is more evidence for exercise than anything else.” Next time you’re facing a long day, you could take a pill and see what happens.
For obvious reasons, it’s difficult for researchers to know just how common the “smart drug” or “neuro-enhancing” lifestyle is. However, a few recent studies suggest cognition hacking is appealing to a growing number of people. A survey conducted in 2016 found that 15% of University of Oxford students were popping pills to stay competitive, a rate that mirrored findings from other national surveys of UK university students. In the US, a 2014 study found that 18% of sophomores, juniors, and seniors at Ivy League colleges had knowingly used a stimulant at least once during their academic career, and among those who had ever used uppers, 24% said they had popped a little helper on eight or more occasions. Anecdotal evidence suggests that pharmacological enhancement is also on the rise within the workplace, where modafinil, which treats sleep disorders, has become particularly popular.
Smart Pill is formulated with herbs, amino acids, vitamins and co-factors to provide nourishment for the brain, which may enhance memory, cognitive function, and clarity. , which may enhance memory, cognitive function, and clarity. In a natural base containing potent standardized extract 24% flavonoid glycosides. Fast acting super potent formula. A unique formulation containing a blend of essential nutrients, herbs and co-factors.
“Cavin, you are phemomenal! An incredulous journey of a near death accident scripted by an incredible man who chose to share his knowledge of healing his own broken brain. I requested our public library purchase your book because everyone, those with and without brain injuries, should have access to YOUR brain and this book. Thank you for your legacy to mankind!”
In 3, you’re considering adding a new supplement, not stopping a supplement you already use. The I don’t try Adderall case has value $0, the Adderall fails case is worth -$40 (assuming you only bought 10 pills, and this number should be increased by your analysis time and a weighted cost for potential permanent side effects), and the Adderall succeeds case is worth $X-40-4099, where$X is the discounted lifetime value of the increased productivity due to Adderall, minus any discounted long-term side effect costs. If you estimate Adderall will work with p=.5, then you should try out Adderall if you estimate that 0.5 \times (X-4179) > 0 ~> $X>4179$. (Adderall working or not isn’t binary, and so you might be more comfortable breaking down the various how effective Adderall is cases when eliciting X, by coming up with different levels it could work at, their values, and then using a weighted sum to get X. This can also give you a better target with your experiment- this needs to show a benefit of at least Y from Adderall for it to be worth the cost, and I’ve designed it so it has a reasonable chance of showing that.)
Interesting. On days ranked 2 (below-average mood/productivity), nicotine seems to have boosted scores; on days ranked 3, nicotine hurts scores; there aren’t enough 4’s to tell, but even ’5 days seem to see a boost from nicotine, which is not predicted by the theory. But I don’t think much of a conclusion can be drawn: not enough data to make out any simple relationship. Some modeling suggests no relationship in this data either (although also no difference in standard deviations, leading me to wonder if I screwed up the data recording - not all of the DNB scores seem to match the input data in the previous analysis). So although the 2 days in the graph are striking, the theory may not be right.
"A system that will monitor their behavior and send signals out of their body and notify their doctor? You would think that, whether in psychiatry or general medicine, drugs for almost any other condition would be a better place to start than a drug for schizophrenia," says Paul Appelbaum, director of Columbia University's psychiatry department in an interview with the New York Times.
Drugs and catastrophe are seemingly never far apart, whether in laboratories, real life or Limitless. Downsides are all but unavoidable: if a drug enhances one particular cognitive function, the price may be paid by other functions. To enhance one dimension of cognition, you’ll need to appropriate resources that would otherwise be available for others.
The U.S. Centers for Disease Control and Prevention estimates that gastrointestinal diseases affect between 60 and 70 million Americans every year. This translates into tens of millions of endoscopy procedures. Millions of colonoscopy procedures are also performed to diagnose or screen for colorectal cancers. Conventional, rigid scopes used for these procedures are uncomfortable for patients and may cause internal bruising or lead to infection because of reuse on different patients. Smart pills eliminate the need for invasive procedures: wireless communication allows the transmission of real-time information; advances in batteries and on-board memory make them useful for long-term sensing from within the body. The key application areas of smart pills are discussed below.
I started with the 10g of Vitality Enhanced Blend, a sort of tan dust. Used 2 little-spoonfuls (dust tastes a fair bit like green/oolong tea dust) into the tea mug and then some boiling water. A minute of steeping and… bleh. Tastes sort of musty and sour. (I see why people recommended sweetening it with honey.) The effects? While I might’ve been more motivated - I hadn’t had caffeine that day and was a tad under the weather, a feeling which seemed to go away perhaps half an hour after starting - I can’t say I experienced any nausea or very noticeable effects. (At least the flavor is no longer quite so offensive.)
(On a side note, I think I understand now why modafinil doesn’t lead to a Beggars in Spain scenario; BiS includes massive IQ and motivation boosts as part of the Sleepless modification. Just adding 8 hours a day doesn’t do the world-changing trick, no more than some researchers living to 90 and others to 60 has lead to the former taking over. If everyone were suddenly granted the ability to never need sleep, many of them would have no idea what to do with the extra 8 or 9 hours and might well be destroyed by the gift; it takes a lot of motivation to make good use of the time, and if one cannot, then it is a curse akin to the stories of immortals who yearn for death - they yearn because life is not a blessing to them, though that is a fact more about them than life.)
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https://brilliant.org/problems/lattice-path/
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# Getting From Here To There On A Lattice Grid
Discrete Mathematics Level 5
What is 8 more than the mean area under a path of length 129 that goes only right or up through a square grid and starts at the origin?
Note: If the path ends at $$(X,Y)$$, then the area is bounded by the path, the $$x$$-axis, and the line $$x = X$$.
×
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http://cms.math.ca/10.4153/CJM-2003-015-7
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location: Publications → journals → CJM
Abstract view
# The Maximum Number of Points on a Curve of Genus $4$ over $\mathbb{F}_8$ is $25$
Published:2003-04-01
Printed: Apr 2003
• David Savitt
Format: HTML LaTeX MathJax PDF PostScript
## Abstract
We prove that the maximum number of rational points on a smooth, geometrically irreducible genus 4 curve over the field of 8 elements is 25. The body of the paper shows that 27 points is not possible by combining techniques from algebraic geometry with a computer verification. The appendix shows that 26 points is not possible by examining the zeta functions.
MSC Classifications: 11G20 - Curves over finite and local fields [See also 14H25] 14H25 - Arithmetic ground fields [See also 11Dxx, 11G05, 14Gxx]
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http://mathhelpforum.com/pre-calculus/104142-can-you-colve-x.html
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# Thread: can you colve for x?
1. ## can you colve for x?
Solve the equation for x.
Solve the equation for x.
First note that 256=4^4 so we change the question into
$4^{x-x^2}=\frac{1}{(4^4)^x}=\frac{1}{4^{4x}}$
Multiply both sides by $4^{4x}$ to get $4^{4x}\cdot 4^{x-x^2}=1$
$4^{4x+x-x^2}=1$
$4^{5x-x^2}=1$
And we need the exponent to be 0 since $x^0=1$ (you can take the log of both sides, but log 1=0 so we reach the same conclusion)
So now just solve $5x-x^2=0$
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https://www.tubesandmore.com/products/guitar_parts?sort=recent&viewmode=grid&filters=668a408c400a2527
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# Guitar Parts & Pickups
Guitars can lead a rough life and replacement parts can bring your axe to like new condition. But did you know that you can also change components to achieve different sounds? The options are endless!
Nut - Bone, for Fender, 44.45mm X 3.3mm X 6.35, Flat
Bone nut for Fender® , 44.45mm x 3.3mm x 6.35mm at highest point with flat bottom.
$3.95 Nut - Graphite, for Fender, blank unslotted This graphite nut blank will work for most Fender® and similar style guitars and basses. It is NOT slotted and does require final shaping and fitting to exact size. It has a radiused bottom. • Length = 2 1/64 inches (51.25mm) • Height = 11/64 inches (4.55mm) • Thickness = 1/8 inch (3.1mm)$4.55
Nut - Bone, for Gibson, 43mm X 5.9mm X 8mm, Flat
Bone nut for Gibson®, 43mm x 5.9mm x 8mm at highest point with flat bottom.
$5.55 Nut - Plastic construction, for Stratocaster Stratocaster guitar nut - plastic construction$1.95
Nut - Bone, for Fender, 44.45mm X 3.3mm X 6.35, Radiused
Bone nut for Fender® , 44.45mm x 3.3mm x 6.35mm with radiused bottom.
$4.25 Nut - Brass, for Fender, blank un-slotted This brass nut blank will work for most Fender® and similar style guitars and basses. It is NOT slotted and does require final shaping and fitting to exact size. • Thickness = 9/64 inches (3.47mm) • Flat Bottom Length = 1 11/16 inches (43 mm) • Height at ends = 13/64 inches (5.25mm) • Height at middle = 15/64 inches (6mm)$6.50
Nut - Graphite, for Fender, with Slots
Graphite nut for Fender® This graphite nut will work for most Fender® and similar style guitars. It is slotted, but does require final shaping and fitting to exact size.
PLEASE NOTE: Because this nut tapers in both thickness from top to bottom and height on the fret board side vs. the headstock side all measurements for those dimensions were taken at the center of the nut.
• Length = 1 41/64 inches (41.52mm)
• Height #1 (fretboard side) = 13/64 inches (5.06mm)
• Height #2 (headstock side) = 13/64 inches (5mm)
• Thickness at bottom = 9/64 inches (3.46mm)
• Thickness at top = 1/8 inches (3.1mm)
$4.55 Nut - Graphite, for Gibson, slotted This graphite nut will work for most Gibson® and similar style guitars and basses. It is slotted but does require final shaping and fitting to exact size. PLEASE NOTE: Because this nut tapers in both thickness from top to bottom and height on the fret board side vs. the headstock side all measurements for those dimensions were taken at the center of the nut. • Length = 1 23/32 inches (43.75mm) • Height #1 (fretboard side) = 5/16 inches (7.81mm) • Height #2 (headstock side) = 9/32 inches (7mm) • Thickness at bottom = 15/64 inches (6.1mm) • Thickness at top = 3/16 inches (4.78mm)$4.55
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http://energyresources.asmedigitalcollection.asme.org/article.aspx?articleid=2715668&resultClick=1
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0
Research Papers: Energy Systems Analysis
# Experimental Investigation of the Effect of Nanofluid on Thermal Energy Storage System Using Clathrate
[+] Author and Article Information
M. A. M. Hassan
Mechanical Power Engineering Department,
Faculty of Engineering,
Helwan University,
Mataria, Cairo 11718, Egypt
e-mail: [email protected]
H. M. Abdel-Hameed
Mechanical Power Engineering Department,
Faculty of Engineering,
Helwan University,
Mataria, Cairo 11718, Egypt
e-mail: [email protected]
Osama E. Mahmoud
Mechanical Power Engineering Department,
Faculty of Engineering,
Helwan University,
Mataria, Cairo 11718, Egypt
e-mail: [email protected]
1Corresponding author.
Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received April 19, 2018; final manuscript received November 9, 2018; published online November 30, 2018. Assoc. Editor: Esmail M. A. Mokheimer.
J. Energy Resour. Technol 141(4), 042003 (Nov 30, 2018) (8 pages) Paper No: JERT-18-1279; doi: 10.1115/1.4042004 History: Received April 19, 2018; Revised November 09, 2018
## Abstract
Climatic change illustrates the need to new policy of load management. In this research, a special design of thermal energy storage (TES) system, with an appropriate storage medium that is suitable for residential and commercial buildings has been constructed and commissioned. Direct contact heat transfer is a significant factor to enhance the performance of TES. Numerous experimental runs were conducted to investigate the clathrate formation and the characteristics of the proposed TES cooling system; in addition, the effect of using nanofluid particles Al2O3 on the formation of clathrate under different operating parameters was evaluated. The experiments were conducted with a fixed amount of water 15 kg, mass of refrigerant to form clathrate of 6.5 kg, nanofluid particles concentration ranged from 0.5% to 2% and the mass flux of refrigerant varied from 150 to 300 kg/m2 s. The results indicate that there is a significant effect of using nanoparticles concentration on the charging time of the clathrate formation. The percentage of reduction in charging time of about 22% was achieved for high nanoparticles concentration. In addition, an enhancement in charging time by increasing the refrigerant flow rate reaches 38% when the mass flux varied from 200 to 400 kg/m2 s. New correlation describing the behavior of the temperatures with the charging time at different nanoparticles concentrations is presented.
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Liang, D. , Wang, R. , Guo, K. , and Fan, S. , 2001, “ Prediction of Refrigerant Gas Hydrates Formation Conditions,” J. Therm. Sci., 10(1), pp. 64–68.
Li, Z. , Kaihua, G. , Yongli, Z. , Bifen, S. , and Jiawei, Z. , 2000, “ Phase Equilibrium Calculation for Refrigerant Simple Gas Hydrates,” J. Eng. Thermophys., 21(1), pp. 13–16.
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## Figures
Fig. 1
Fig. 2
The schematic diagram of the experimental test-rig
Fig. 3
The thermocouple distribution within the storage tank
Fig. 4
Storage media thermal behavior during cycle operation at different nanofluid concentration with refrigerant mass flux 150 kg/m2·s
Fig. 5
Storage media thermal behavior during cycle operation at different nanofluid concentration with refrigerant mass flux 230 kg/m2·s
Fig. 6
Storage media thermal behavior during cycle operation at different nanofluid concentration with refrigerant mass flux 300 kg/m2·s
Fig. 7
Storage media thermal behavior during complete cycle operation
Fig. 8
Storage media thermal behavior during complete cycle operation
Fig. 9
Pressure variation during charging process
Fig. 10
Variation of compression ratio and volumetric efficiency during charging process
Fig. 11
Variation of compressor power and cooling load charging process
Fig. 12
Variation of COP during charging process
## Errata
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https://stacks.math.columbia.edu/tag/0B1R
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Lemma 43.23.3. Let $V$ be a vector space of dimension $n + 1$. Let $Y, Z \subset \mathbf{P}(V)$ be closed subvarieties. There is a nonempty Zariski open $U \subset \mathbf{P}(V)$ such that for all closed points $p \in U$ we have
$Y \cap r_ p^{-1}(r_ p(Z)) = (Y \cap Z) \cup E$
with $E \subset Y$ closed and $\dim (E) \leq \dim (Y) + \dim (Z) + 1 - n$.
Proof. Set $Y' = Y \setminus Y \cap Z$. Let $y \in Y'$, $z \in Z$ be closed points with $r_ p(y) = r_ p(z)$. Then $p$ is on the line $\overline{yz}$ passing through $y$ and $z$. Consider the finite type scheme
$T = \{ (y, z, p) \mid y \in Y', z \in Z, p \in \overline{yz}\}$
and the morphism $T \to \mathbf{P}(V)$ given by $(y, z, p) \mapsto p$. Observe that $T$ is irreducible and that $\dim (T) = \dim (Y) + \dim (Z) + 1$. Hence the general fibre of $T \to \mathbf{P}(V)$ has dimension at most $\dim (Y) + \dim (Z) + 1 - n$, more precisely, there exists a nonempty open $U \subset \mathbf{P}(V) \setminus (Y \cup Z)$ over which the fibre has dimension at most $\dim (Y) + \dim (Z) + 1 - n$ (Varieties, Lemma 33.20.4). Let $p \in U$ be a closed point and let $F \subset T$ be the fibre of $T \to \mathbf{P}(V)$ over $p$. Then
$(Y \cap r_ p^{-1}(r_ p(Z))) \setminus (Y \cap Z)$
is the image of $F \to Y$, $(y, z, p) \mapsto y$. Again by Varieties, Lemma 33.20.4 the closure of the image of $F \to Y$ has dimension at most $\dim (Y) + \dim (Z) + 1 - n$. $\square$
In your comment you can use Markdown and LaTeX style mathematics (enclose it like $\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).
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https://socratic.org/questions/what-are-some-examples-of-alternative-energy-resources
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Earth Science
Topics
# What are some examples of alternative energy resources?
Feb 22, 2015
Examples of alternative energy sources besides fossil fuels (coal, natural gas, oil) could include harnessing the power of the sun (solar), wind, waves (hydro), or the earth itself (geothermal). These energy sources are considered 'renewable' energy sources, as they will not run out.
Nuclear power is also considered 'renewable' as the earth contains a limited amount of nuclear fuel, but there is enough to last for thousands of years. So while this energy source will eventually run out, it won't be for a very long time. However, although nuclear power does not produce any atmospheric pollution, there is still the matter of disposing of the radioactive nuclear fuel safely.
##### Impact of this question
253 views around the world
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http://math.stackexchange.com/questions/146241/there-are-no-simple-groups-of-order-2n-5-for-n-geq-4
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# There are no simple groups of order $2^n.5$ for $n\geq 4$.
How do you show that there are no simple groups of order $2^n\times 5$ for $n\geq 4$, without using the theorem that a finite group of order $p^nq^m$, where p, q are primes and $m,n\geq 1$ is not simple.
I have a hint to 'use the coset action determined by the Sylow 2-subgroup', but I'm not sure what this means.
-
If this is homework please tag this with the homework tag – Belgi May 17 '12 at 11:29
It's not homework, I'm just going through some questions that don't come with solutions. – 09867 May 17 '12 at 11:30
Hint: There are either 5 or 1 Sylow 2-subgroups (why?). Assuming there are 5 and we let $G$ act by conjugation on the Sylow 2-subgroups we get a non-trivial homomorphism from $G$ to $S_5$. What can we say about its kernel?
@09867 What's the order of G and what's the order of $S_5$. – JSchlather May 17 '12 at 12:20
$|S_5|=120$, $|G|=2^n.5$. So if $n\geq 4$ $|G|\geq 80$. So.. this homomorphism can't exist because 80 doesn't divide 120? – 09867 May 17 '12 at 12:25
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https://tex.stackexchange.com/questions/595545/about-saving-a-drawing-as-a-tikz-file
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# About saving a drawing as a tikz file
This answer describes how to include a tikz file in your document, whether it is an article, a book or a beamer presentation.
It works fine, up until the point that you call for some other libraries.
Suppose I have the following graphics:
% File myDrawing.tex
\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\usetikzlibrary{math} %needed tikz library
\tikzmath{\x1 = 1; \y1 =1; \x2 = \x1 + 1; \y2 =\y1 +3; }
% Using the variables for drawing
\begin{tikzpicture}
\draw[very thick, -stealth] (\x1, \y1)--(\x2, \y2);
\end{tikzpicture}
\end{document}
As you can see it consists of mainly a tikzpicture environment, but it also calls for the math tikz library, and declares variables \x1 and \y1 outside the tikzpicture environment.
As yet another example, consider this pgfplots part of code:
\documentclass{standalone}
\usepackage{pgfplots}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}
\begin{axis}
\end{axis}
\end{tikzpicture}
\end{document}
It makes use of the arrows library and sets the pgfplots version, outside the tikzpicture environment, too.
Is it possible to create a file myDrawing.tikz that I can transplant in my main document, and also make use of the tikzscale package? If the answer is yes, then how? Can you post an example?
I am having difficulties with correctly and nicely (in)putting a drawing inside my document. Particularly with the height-to-width aspect ratio.
Until now I saved the drawing as a tex file, under a standalone document class and worked with includestandalone[width=...]{path/to/file} as described here. But sometimes I want the figure to be inside a \begin{columns} \column{0.4\textwidth} \end{columns} environment in a beamer presentation, and sometimes in the side margin of a book document, with a width=\marginparwidth option.
The tikzscale package looks very promising, but its documentation instructs its use only when working with tikz files.
• This sounds a bit complicated :) do you use the same drawings in many different documents? If not then adding the full code of the drawings in the document itself seems like the easiest solution - possibly combined with an editor that supports code folding if you think that all the code is cluttering the view. – Marijn May 3 at 19:04
• @Marijn I would give it a try, as I am working with Vim and folding is possible there. Can you show explicitly how? – tush May 3 at 19:05
• Most commands like \tikzset or \pgfmath can be used both inside or outside a tikzpicture environment. The only exception I know of is \tikzfadings (see tex.stackexchange.com/questions/277784/…). – John Kormylo May 3 at 19:14
• @John Kormylo I didn't know that! That works, and it sounds like a good answer to my question. – tush May 3 at 20:42
1. Enter full code. Set the foldmethod to manual.
2. Select tikzpicture enviroment with visual selection (ctrl-v)
3. Press zf to fold. Continue editing the rest of the document. If you want to go inside the fold, press zd.
4. When you exit Vim enter :mkview to save the folds. When you start Vim the next time the code shows unfolded. Enter :loadview to re-apply the folds from the previous session.
Note that you can of course automate most of the commands in your .vimrc.
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https://groups.google.com/g/comp.lang.scheme/c/ZQHqjFSxoHs/m/sci9p7QSiwUJ
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# How to write dirty R5RS macros
84 views
### [email protected]
Mar 27, 2002, 3:53:45 PM3/27/02
to
observationally equivalent to referentially opaque macros. These
macros capture user identifiers and allow their own identifiers being
captured by closest lexical bindings. In other words, we will write
macros that do the things that the R5RS macro system has sought to
prevent. This article will also show how to 're-define' a lambda form
while still keeping the original 'lambda' available. The redefined
lambda acts as if it was infected by a virus, which propagates through
the lambda's body infecting other lambdas in turn. Although we will be
re-defining all binding forms, we will preserve the semantics of
Scheme as given in R5RS.
* Referential transparency of macros
* Petrofsky's extraction
* Towards the full referential opaqueness: a mylet form
* Achieving the full referential opaqueness: redefining all binding forms
* Referential transparency of macros
The referential transparency of macros means that all identifiers in
the macro code (other than pattern variables) refer to the bindings
that existed when the macro was defined rather to the bindings that
exist at the point of invocation. The transparency has two facets. The
first one demands that bindings introduced by macros should not
capture free identifiers in macro arguments.
Let's consider the following macro:
(define-syntax m1
(syntax-rules ()
((m1 body) (let ((i 10)) body))))
A form (m1 body) expands into (let ((i 10)) body). Naive, referentially
opaque expansion of (m1 (* 1 i)) would have produced
(let ((i 10)) (* 1 i))
The binding of 'i' introduced by the macro would have captured the
free variable 'i' occurring in the 'body'. The referential
transparency and hygiene prevent this capture through systematic
renaming of introduced identifiers. Therefore,
(let ((i 1))
(m1 (* 1 i)))
actually expands to
(let ((i~2 1))
(let ((i~5 10)) (* 1 i~2))
and gives the result 1. The identifier i~2 is different from i~5: we
will call them of different _colors_.
The second facet of the referential transparency demands that free
identifiers in a macro expansion should not be captured by bindings
that textually appear after the macro definition. If a macro expansion
introduces a free identifier, the identifier refers to the binding
occurrence which was in effect when the macro was defined. E.g.
(define foo 1)
(define-syntax mm
(syntax-rules ()
((mm) foo)))
The following form
(let ((foo 2))
(mm))
expands into
(let ((foo~1 2))
foo)
and yields 1 when evaluated. The local 'let' binds 'foo' of a
different color, and therefore, does not capture 'foo' introduced by
macro mm. If foo was not defined when macro mm was introduced, (mm)
will always lead to an "unbound identifier" error.
We will now show how to write R5RS macros that violate both aspects of
referential transparency. The main idea has been introduced by Al
Petrofsky in an article
How to write seemingly unhygienic macros using syntax-rules
Date: 2001-11-19 01:23:33 PST
In that article, Al Petrofsky has shown how to circumvent the weak
generalizes Petrofsky's idea to attack the full referential transparency.
* Petrofsky's extraction
For completeness and reference we will derive the Petrofsky technique
first. The derivation below differs from the one in Petrofsky's
article in insignificant details: I didn't remember the details and
therefore wrote the macros below by following the general idea.
Petrofsky's article deals with a weak form of the referential
transparency: capturing a free identifier in the user code that has
not been rebound. That is, we'd like to write a macro m1 so that
(m1 10 body) expands into
(let ((i 10)) body)
such that the binding of 'i' captures possible occurrences of 'i' in
the 'body'. We assume that there are no other bindings of 'i' in the
scope of '(m1 10 body)', or 'i' was defined early in the global scope
and not re-defined since. This assumption is the distinction between
the 'weak' referential opaqueness and the true one.
Developing even weakly referentially-opaque macros is challenging. We
cannot just write
(define-syntax m1
(syntax-rules ()
((_ val body) (let ((i val)) body))))
because
(m1 10 (* 1 i))
will expand into
(let ((i~5 10)) (* 1 i))
where 'i' in (* 1 i) refers to the top-level binding of 'i' or
remains undefined. However, we can write
(define-syntax m1-i
(syntax-rules ()
((_ i val body) (let ((i val)) body))))
that is, specifically pass the variable to capture. In that case,
(m1-i i 10 (* 1 i))
expands into
(let ((i 10)) (* 1 i))
and the capture occurs. Hence to circumvent the hygiene in the weak
sense, we only need to find a way to convert an invocation of m1 into
an invocation of m1-i. Macro m1-i requires the explicit specification
of the symbol to capture -- which we can get by extracting the symbol
'i' (_together_ with its color) from the argument of m1. That's the
essence and the elegance of the Petrofsky's idea. Once we have the
rightly colored occurrence of 'i', we can use it in the binding form and
effect the capture.
The extraction of the colored identifiers from a form is done by the
following macro extract:
; Extract a colored identifier from a form
; extract SYMB BODY CONT
; BODY is a form that may contain an occurrence of an identifier that
; refers to the same binding occurrence as SYMB, perhaps with a different
; color. CONT is a form of the shape (K-HEAD K-IDL . K-ARGS)
; where K-IDL are K-ARGS are S-expressions representing lists or the
; empty list.
; The extract macro expands into
; (K-HEAD (extr-id . K-IDL) . K-ARGS)
; where extr-id is the extracted colored identifier. If symbol SYMB does
; not occur in BODY at all, extr-id is identical to SYMB.
(define-syntax extract
(syntax-rules ()
((_ symb body _cont)
(letrec-syntax
((tr
(syntax-rules (symb)
((_ x symb tail (cont-head symb-l . cont-args))
(cont-head (x . symb-l) . cont-args)) ; symb has occurred
((_ d (x . y) tail cont) ; if body is a composite form,
(tr x x (y . tail) cont)) ; look inside
((_ d #(x . y) tail cont)
(tr x x (y . tail) cont))
((_ d1 d2 () (cont-head symb-l . cont-args))
(cont-head (symb . symb-l) . cont-args)) ; symb does not occur
((_ d1 d2 (x . y) cont)
(tr x x y cont)))))
(tr body body () _cont)))))
The extract macro is the workhorse of the circumvention strategies.
We also need a macro that extracts several identifiers, extract*:
; Extract several colored identifiers from a form
; extract* SYMB-L BODY CONT
; where SYMB-L is the list of symbols to extract, and BODY and CONT
; has the same meaning as in extract, see above.
;
; The extract* macro expands into
; (K-HEAD (extr-id-l . K-IDL) . K-ARGS)
; where extr-id-l is the list of extracted colored identifiers. The extraction
; itself is performed by the macro extract.
(define-syntax extract*
(syntax-rules ()
((_ (symb) body cont) ; only one symbol: use extract to do the job
(extract symb body cont))
((_ _symbs _body _cont)
(letrec-syntax
((ex-aux ; extract symbol-by-symbol
(syntax-rules ()
((_ found-symbs () body cont)
(reverse () found-symbs cont))
((_ found-symbs (symb . symb-others) body cont)
(extract symb body
(ex-aux found-symbs symb-others body cont)))
))
(reverse ; reverse the list of extracted symbols
(syntax-rules () ; to match the order of SYMB-L
((_ res () (cont-head () . cont-args))
((_ res (x . tail) cont)
(reverse (x . res) tail cont)))))
(ex-aux () _symbs _body _cont)))))
Now we can write a macro
(define-syntax m1-dirty-v1
(syntax-rules ()
((_ _val _body)
(let-syntax
((cont
(syntax-rules ()
((_ (symb) val body) (let ((symb val)) body) ))))
(extract i _body (cont () _val _body))))))
Then
(m1-dirty-v1 10 (* 1 i))
expands into
(let ((i~11 10)) (* 1 i~11))
and evaluates to 10, as expected.
The m1-dirty-v1 macro seems to do the job, but it has a flaw. It does
not nest:
(m1-dirty-v1 10
(m1-dirty-v1 20 (* 1 i)))
expands into
(let ((i~16 10)) (let ((i~17~25~28 20)) (* 1 i~16)))
and evaluates to 10 rather than to 20 as we might have expected. The
nested invocation of m1-dirty-v1 violates our assumption of no
bindings of 'i' in the scope of m1-dirty-v1 that was not present at
the time m1-dirty-v1 was defined. The outer invocation of m1-dirty-v1
creates a binding for 'i' -- which violates the weak referential
transparency assumption. Al Petrofsky has also shown how to overcome
the problem. If we bind 'i' and still want m1-dirty-v1 to work as
expected, we need to re-define m1-dirty-v1 in the scope of the new
binding to 'i'. Thus we need a macro that re-defines itself in its own
expansion. We however face a problem:
(m1-dirty-v1 10
(m1-dirty-v1 20 (* 1 i)))
If the outer invocation of m1-dirty-v1 re-defines itself, this
redefinition has to capture the inner invocation of m1-dirty-v1. This
is the same problem of the weak referential opaqueness -- which we
know how to solve, by extracting the colored identifier m1-dirty-v1
from outer macro's body. We need to extract two identifiers: 'i' and
'm1-dirty-v1'. We arrive at the following macro:
; A macro that re-defines itself in its expansion
; m1-dirty-v2 val body
; expands into
; (let ((i val)) body)
; and also re-defines itself in the scope of body.
(define-syntax m1-dirty-v2
(syntax-rules ()
((_ _val _body)
(letrec-syntax
((doit ; it's the continuation from extract*
(syntax-rules () ; myself-symb i-symb are colored ids extracted
((_ (myself-symb i-symb) val body) ; from the 'body'
(let ((i-symb val)) ; first bind the symbol i
(let-syntax ; now re-define oneself
((myself-symb
(syntax-rules ()
((_ val__ body__)
(extract* (myself-symb i-symb) body__
(doit () val__ body__))))))
body))))))
(extract* (m1-dirty-v2 i) _body
(doit () _val _body))))))
Therefore
(m1-dirty-v2 10
(m1-dirty-v2 20 (* 1 i)))
now expands to
(let ((i~26 10)) (let ((i~52 20)) (* 1 i~52)))
and evaluates to 20.
The macro m1-dirty-v2 is still weakly referentially transparent. If we
evaluate
(let ((i 1))
(m1-dirty-v2 10 (* 1 i)))
we obtain
(let ((i 1)) (let ((i~3~22~29 10)) (* 1 i)))
which evaluates to 1 rather than 10.
We can still build a completely referentially opaque m1-dirty
macro. This operation is easier to illustrate on a simpler example,
which breaks the second facet of the referential transparency.
* Towards the full referential opaqueness: a mylet form
In this section, we will try to break the second facet of the
referential transparency: write a macro that allows free identifiers
in its expansion being captured by the closest lexical binding. In
other words, we want to write such a macro mm
(define-syntax mm
(syntax-rules ()
((mm) foo)))
so that the following form
(let ((foo 2))
(mm))
evaluates to 2.
As the first step, let us aim at the referentially opaque capture in
the following form:
(mylet ((foo 2))
(mm))
Where 'mylet' is a new binding form -- which eventually expands to the
regular let. We can use the freedom of implementing mylet to remove
the roadblock to referential opaqueness. The trick is to re-define
dirty macros whenever we add a new binding. This will guarantee the
capture of the latest binding.
Since we want to generate and re-generate macro mm, we need a
generator:
; Macro: make-mm NAME SYMB BODY
; In the scope of BODY, define a macro NAME that expands into a symbol SYMB
(define-syntax make-mm
(syntax-rules ()
((_ name symb body)
(let-syntax
((name
(syntax-rules ()
((_) symb))))
body))))
; (mylet ((var init)) body)
; expands into
; (let ((var init)) body')
; where body' is the body wrapped in the re-definitions of mylet and macro mm.
(define-syntax mylet
(syntax-rules ()
((_ ((_var _init)) _body)
(letrec-syntax
((doit ; The continuation from extract*
(syntax-rules () ; mylet-symb, etc. are extracted from body
((_ (mylet-symb mm-symb foo-symb) ((var init)) body)
(let ((var init)) ; bind the 'var' first
(make-mm mm-symb foo-symb ; now re-generate the macro mm
(letrec-syntax
((mylet-symb ; and re-define myself
(syntax-rules ()
((_ ((var_ init_)) body_)
(extract* (mylet-symb mm-symb foo-symb) (var_ body_)
(doit () ((var_ init_)) body_))))))
body)))
))))
(extract* (mylet mm foo) (_var _body)
(doit () ((_var _init)) _body))))))
Now
(define foo 1)
(mylet ((x 1)) (list (mm) x))
evaluates to (1 1), as expected. (mm) expands to 'foo' defined in the
global environment. However,
(mylet ((foo 2)) (list (mm) foo))
expands to
((lambda (foo~39) (list foo~39 foo~39)) 2)
and evaluates to (2 2). Hence (mm) expanded to foo which was captured
by the local binding! Because mylet constantly re-generates itself, it
nests:
(mylet ((foo 3)) (mylet ((foo 4)) (mylet ((foo 5)) (list foo (mm)))))
expands to
((lambda
(foo~55)
((lambda
(foo~100)
((lambda (foo~142) (list foo~142 foo~142)) 5))
4))
3)
and evaluates to (5 5). To further verify that (mm) captures the lexical
binding, we evaluate
(mylet ((foo 3))
(mylet ((thunk (lambda () (mm))))
(mylet ((foo 4)) (list foo (mm) (thunk)))))
which gives us (4 4 3). The invocation (mm) within the closure 'thunk'
captured foo that was lexically visible at that time, which was 3.
* Achieving the full referential opaqueness: redefining all binding forms
The previous section showed that a a non-hygienic capture is possible
if we can introduce our own binding forms. We can achieve the same
result with the regular binding forms let, let*, letrec and lambda --
if we just re-define them. To be precise we need to 'overload' only
one, fundamental binding form: the lambda itself. The other binders
are defined in terms of lambda.
This redefinition is done by a macro defile, which defiles its
body. It is a bit long, therefore, it is moved to the appendix. We
will consider a few excerpts from that macro's code.
The first notable piece is the following:
(letrec-syntax
...
(lambda-native ; capture the native lambda
(syntax-rules ()
((_ . args) (lambda . args))))
This fragment does what it looks like: it captures the native lambda,
which is needed to effect bindings.
(letrec-syntax
...
((let-symb ; R5RS definition of let, with no ...
(syntax-rules () ; and no named-let, for simplicity
((_ "0" vars inits () . body)
((lambda-symb vars . body) . inits))
((_ "0" vars inits ((var init) . other) . body)
(let-symb "0" (var . vars) (init . inits) other . body))
((_ bindings . body)
(let-symb "0" () () bindings . body))))
This is the _standard_ definition of let (save named let, which is
dropped for simplicity). We can't use a ... pattern because of the
deep nesting of this macro. We redefine 'let' to use our redefined
(letrec
...
(lambda-symb ; re-defined, infected lambda
(syntax-rules ()
((_ _vars _body)
(letrec-syntax
((doit
(syntax-rules ()
((_ (mylet-symb mylet*-symb mylambda-symb
mymm-symb myfoo-symb) vars body)
(lambda-native vars
(make-mm mymm-symb myfoo-symb
(do-defile ; proliferate in the body
(mylet-symb mylet*-symb mylambda-symb
mymm-symb myfoo-symb)
body)))))))
(extract* (let-symb let*-symb lambda-symb mm-symb foo-symb)
(_vars _body)
(doit () _vars _body))))))
We're relying on the lambda-native to create bindings. Right after
that, we redefine all our macros. The infected lambda spreads from one
binding to another.
Let us see how it works:
(defile
(let ((foo 2)) (list (mm) foo))
)
expands into
((lambda (foo~186) (list foo~186 foo~186)) 2)
and predictably evaluates to (2 2). All the infected lambdas are gone:
the expansion result is the regular Scheme code.
Furthermore,
(defile
(let ((foo 2))
(let ((foo 3) (bar (list (mm) foo)))
(list foo (mm) bar)))
)
evaluates to (3 3 (2 2)). The scoping rules of let are respected.
Finally,
(defile
(let* ((foo 2)
(i 3)
(foo 4)
(ft (lambda () (mm))) ; will capture binding of foo to 4
(foo 5)
(ft1 (lambda (foo) (mm))) ; will capture the arg of ft1
(foo 6))
(list foo (mm) (ft) (ft1 7) '(mm)))
)
evaluates to the expected (6 6 4 7 (mm)).
All the examples run with Bigloo 2.4b interpreter and the compiler.
We must point out that the defiled examples behave as if (mm), unless
quoted, were just the variable foo. In other words, as if mm were
defined as a *non-hygienic*, referentially opaque macro
(define-macro (mm) foo)
We have thus demonstrated an observational equivalent of a dirty,
referentially opaque macro, exclusively developed with R5RS, hygienic
macros. The guarantees of R5RS macros can be circumvented.
Appendix.
; This macro defiles its body.
; It re-defines let-forms and the lambda, and defines
; a non-hygienic macro 'mm'. Whenever any binding is introduced,
; the let-forms, the lambdas and 'mm' are redefined.
; The redefined lambda acts as if it were infected by a virus, which
; keeps spreading within lambda's body to infect other lambda's there.
;
; In the following macro, we should have redefined letrec and the named let.
; We omit those forms for simplicity.
(define-syntax defile
(syntax-rules ()
((_ dbody)
(letrec-syntax
((do-defile
(syntax-rules () ; all the overloaded symbols
((_ (let-symb let*-symb lambda-symb mm-symb foo-symb)
body-to-defile)
(letrec-syntax
((let-symb ; R5RS definition of let, with no ...
(syntax-rules () ; and no named-let, for simplicity
((_ "0" vars inits () . body)
((lambda-symb vars . body) . inits))
((_ "0" vars inits ((var init) . other) . body)
(let-symb "0" (var . vars) (init . inits) other
. body))
((_ bindings . body)
(let-symb "0" () () bindings . body))))
(let*-symb ; R5RS definition of let*
(syntax-rules ()
((_ () . body) (let-symb () . body))
((_ (binding . bindings) . body)
(let-symb (binding) (let*-symb bindings . body)))))
(lambda-symb ; re-defined, infected lambda
(syntax-rules ()
((_ _vars _body)
(letrec-syntax
((doit
(syntax-rules ()
((_ (mylet-symb mylet*-symb mylambda-symb
mymm-symb myfoo-symb) vars body)
(lambda-native vars
(make-mm mymm-symb myfoo-symb
(do-defile ; proliferate in the body
(mylet-symb mylet*-symb mylambda-symb
mymm-symb myfoo-symb)
body)))))))
(extract* (let-symb let*-symb lambda-symb
mm-symb foo-symb)
(_vars _body)
(doit () _vars _body))))))
(lambda-native ; capture the native lambda
(syntax-rules ()
((_ . args) (lambda . args))))
)
body-to-defile)))))
(extract* (let let* lambda mm foo) dbody
(do-defile () dbody))
))))
### David Golden
Mar 27, 2002, 5:03:03 PM3/27/02
to
[email protected] wrote:
> observationally equivalent to referentially opaque macros. These
> macros capture user identifiers and allow their own identifiers being
> captured by closest lexical bindings. In other words, we will write
> macros that do the things that the R5RS macro system has sought to
> prevent. This article will also show how to 're-define' a lambda form
> while still keeping the original 'lambda' available. The redefined
> lambda acts as if it was infected by a virus, which propagates through
> the lambda's body infecting other lambdas in turn. Although we will be
> re-defining all binding forms, we will preserve the semantics of
> Scheme as given in R5RS.
>
Spectacular stuff !
--
Don't eat yellow snow.
### Al Petrofsky
Mar 27, 2002, 8:00:39 PM3/27/02
to
[email protected] ([email protected]) writes:
> We have thus demonstrated an observational equivalent of a dirty,
> referentially opaque macro, exclusively developed with R5RS, hygienic
> macros. The guarantees of R5RS macros can be circumvented.
I don't think you can quite put it that way. The guarantees of r5rs
macros are with respect to the r5rs binding forms. What you have
shown, rather, is a set of binding forms, developed on top of r5rs,
which create bindings that are not transparent to the variable
references of a particular macro.
That's what I was jokingly suggesting earlier this month in article
<[email protected]>, and I'm impressed to see you
actually did it. I like how the aptly-named defile macro uses
identifier extraction to set up the initial bindings of lambda, let,
etc.. That's a little simpler than how I did things in my November
article, and it nicely avoids the problem of redefining top-level
lambda.
Pondering the possibilities, I think it would be straightforward to
add do, letrec, and let-syntax to the binding forms that defile
supports. Letrec-syntax would be trickier, but possible, and internal
define would be impossible (that is, impossible if you want to support
macros that expand into internal definitions). The only other
non-top-level r5rs binding construct is syntax-rules, which binds
pattern variables. Although the concept of referential transparency
is meaningful for pattern variables, it is hard to conceive of a macro
that would want to insert an identifier reference that would be
captured by a pattern variable binding. I think that as a result of
the fact that the region of a pattern variable is a template rather
than an expression, it would work out that the macro would have to do
its own identifier extractions, and defile would not need to do
anything special with syntax-rules.
-al
### Al Petrofsky
Mar 28, 2002, 7:50:21 PM3/28/02
to
A couple notes after fiddling with your code a bit:
[email protected] ([email protected]) writes:
> (define-syntax extract
...
> ((_ d #(x . y) tail cont)
...
> All the examples run with Bigloo 2.4b interpreter and the compiler.
Does this bogus dotted vector really work in Bigloo? I know some
readers accept #(a . (b c)) as a synonym for #(a b c), but I can't
imagine how bigloo represents #(x . y) after reading it. (Perhaps it
is silently converted to #(x)? That is, (x . y) gets passed to
a version of list->vector that ignores the list's last cdr. If so,
you should probably report that as a Bigloo bug.)
> (letrec-syntax
> ...
> (lambda-native ; capture the native lambda
> (syntax-rules ()
> ((_ . args) (lambda . args))))
>
> This fragment does what it looks like: it captures the native lambda,
> which is needed to effect bindings.
This is not actually necessary. In the region of lambda-native, the
non-native lambda is named lambda-symb, so there is no conflict. You
can drop this clause from the letrec-syntax bindings and replace the
one call to lambda-native with a call to lambda. (At some point in
the expansion, lambda-sym will be lambda, but thanks to referential
transparency, you needn't worry about that.)
-al
### [email protected]
Mar 28, 2002, 9:27:21 PM3/28/02
to
Al Petrofsky <[email protected]> wrote in message news:<[email protected]>...
> [email protected] ([email protected]) writes:
>
> > We have thus demonstrated an observational equivalent of a dirty,
> > referentially opaque macro, exclusively developed with R5RS, hygienic
> > macros. The guarantees of R5RS macros can be circumvented.
>
> I don't think you can quite put it that way. The guarantees of r5rs
> macros are with respect to the r5rs binding forms.
Do the perverted lambdas introduced in the previous article satisfy
R5RS? A brief check of R5RS seems to answer affirmatively. R5RS
Section 4.1.4 describes the semantics of a lambda form at
run-time. The defiled lambda seems to have exactly the same semantics
(because it macro-expands into the native lambda). Since a lambda is
not a macro (in most of the Schemes), R5RS is silent on how lambdas
should be treated by a macro expander. The defiled let and let*
binding forms should comply with R5RS as well, because these forms
relate to the overloaded lambda as the original let and let* forms
relate to the original lambda. R5RS Section 4.3 does not outlaw the
construction in the previous article, because the 'defile' macro is
truly a R5RS macro.
If a Scheme system with defiled lambda and other binding forms
nevertheless complies with R5RS, it casts doubt on the assertion that
R5RS macros are referentially transparent.
### Thomas Bushnell, BSG
Mar 28, 2002, 11:45:41 PM3/28/02
to
[email protected] ([email protected]) writes:
> If a Scheme system with defiled lambda and other binding forms
> nevertheless complies with R5RS, it casts doubt on the assertion that
> R5RS macros are referentially transparent.
Hrm, I'm inclined to a holistic view of the standard. Such defiled
lambdas, because they allow the violation of referential transparency,
are not actually standard compliant.
Perhaps I'm missing some subltety, however... enlighten me if so.
### Sander Vesik
Mar 29, 2002, 10:07:52 AM3/29/02
to
Thomas Bushnell, BSG <[email protected]> wrote:
> [email protected] ([email protected]) writes:
>
>> If a Scheme system with defiled lambda and other binding forms
>> nevertheless complies with R5RS, it casts doubt on the assertion that
>> R5RS macros are referentially transparent.
>
> Hrm, I'm inclined to a holistic view of the standard. Such defiled
> lambdas, because they allow the violation of referential transparency,
> are not actually standard compliant.
*IF* these are written using nothing but R5RS compliant constructs and
not relying on any undefined behaviour behaving in a certain way, are
definately standard compliant. In fact, an application of such is
probably testing the compliance of various implementations 8-)
>
> Perhaps I'm missing some subltety, however... enlighten me if so.
>
That R5RS facilities are more capable than people usualy realise and thus
some things commonly asserted about them need to necessarily be true?
--
Sander
+++ Out of cheese error +++
### Al Petrofsky
Mar 29, 2002, 3:41:23 PM3/29/02
to
[email protected] ([email protected]) writes:
> Al Petrofsky <[email protected]> wrote in message news:<[email protected]>...
> > [email protected] ([email protected]) writes:
> >
> > > We have thus demonstrated an observational equivalent of a
> > > dirty, referentially opaque macro, exclusively developed with
> > > R5RS, hygienic macros. The guarantees of R5RS macros can be
> > > circumvented.
> >
> > I don't think you can quite put it that way. The guarantees of
> > r5rs macros are with respect to the r5rs binding forms.
>
> Do the perverted lambdas introduced in the previous article satisfy
> R5RS? [...] R5RS is silent on how lambdas should be treated by a
> macro expander.
The r5rs 4.3 discussion of the referential transparency of
syntax-rules transformers states:
* If a macro transformer inserts a free reference to an identifier,
the reference refers to the binding that was visible where the
transformer was specified, regardless of any local bindings that
may surround the use of the macro.
In other words, the local bindings introduced by lambda and the other
r5rs binding forms must be transparent to free identifier references
inserted by syntax-rules expansions.
> If a Scheme system with defiled lambda and other binding forms
> nevertheless complies with R5RS, it casts doubt on the assertion that
> R5RS macros are referentially transparent.
SICP shows how to implement a call-by-name scheme system on top of
r5rs scheme. Does that cast doubt on the assertion that r5rs scheme
is call-by-value?
-al
### [email protected]
Mar 31, 2002, 5:47:29 PM3/31/02
to
I have verified that the defiled R5RS macros work in S48 (after you
remove the #(a . b) pattern from the macro expand, see below). All
examples pass, although it takes a second. The ,expand command in S48
can nicely show the result of the macro expansion.
Al Petrofsky <[email protected]> wrote in message news:<[email protected]>...
> > (define-syntax extract ...
> > ((_ d #(x . y) tail cont) ...
> > All the examples run with Bigloo 2.4b interpreter and the compiler.
> Does this bogus dotted vector really work in Bigloo?
I'm sorry to say that I never tested that case. I have never come
across a practical example of vector patterns. Bigloo accepts #(a
. b) pattern, but it doesn't work as I expected. SCM and S48 do not
even accept #(a . b). SCM and S48 do take correct vector patterns,
e.g., #(a b), but they fail to match against them. Thus vector
patterns in SCM and S48 don't seem to work, at least for me.
> > (letrec-syntax
> > ...
> > (lambda-native ; capture the native lambda
> > (syntax-rules ()
> > ((_ . args) (lambda . args))))
> >
> > This fragment does what it looks like: it captures the native lambda,
> > which is needed to effect bindings.
> This is not actually necessary.
I'm afraid this is necessary -- at least for S48. If you omit that
declaration,
,expand (defile (let ((foo 2)) (list (mm) foo)))
yields
'((#(>> #(>> #(>> let let 1673) #{Generated #{Generated doit 1635}
1650} 1654) #{Generated #{Generated #{Generated lambda-native 1635}
1650} 1654} 1674) (foo) (list foo foo)) 2)
However, with the unmodified defile as given in the article,
,expand (defile (let ((foo 2)) (list (mm) foo)))
prints
'((lambda (foo) (list foo foo)) 2)
a neat, albeit perverted result.
Still, your point is valid: defile does use referential transparency.
That's the reason lambda-native redefinition works at all. It's
rather ironic that an attack on the referential transparency itself
relies on some form of the referential transparency.
### Al Petrofsky
Mar 31, 2002, 10:15:43 PM3/31/02
to [email protected]
[email protected] ([email protected]) writes:
> Al Petrofsky <[email protected]> wrote in message news:<[email protected]>...
> > > (define-syntax extract ...
> > > ((_ d #(x . y) tail cont) ...
> > > All the examples run with Bigloo 2.4b interpreter and the compiler.
> > Does this bogus dotted vector really work in Bigloo?
>
> I'm sorry to say that I never tested that case. I have never come
> across a practical example of vector patterns.
The very practical example, for which vector patterns were added to
the spec between r4rs and r5rs, is quasiquote.
> SCM and S48 do take correct vector patterns, e.g., #(a b), but they
> fail to match against them.
It works for me in scm 5d2:
(require 'macro)
(let-syntax ((m (syntax-rules () ((_ #(a b)) (+ a b)))))
(m #(1 2)))
=> 3
It's possible S48 implements the r4rs spec, in which case vector
patterns are matched according to equal?, and the following example
will still work:
(let-syntax ((m (syntax-rules () ((_ #(a b)) (+ 1 2)))))
(m #(a b)))
=> 3
> > > This fragment does what it looks like: it captures the native lambda,
> > > which is needed to effect bindings.
> > This is not actually necessary.
>
> I'm afraid this is necessary -- at least for S48. If you omit that
> declaration,
> ,expand (defile (let ((foo 2)) (list (mm) foo)))
> yields
> '((#(>> #(>> #(>> let let 1673) #{Generated #{Generated doit 1635}
> 1650} 1654) #{Generated #{Generated #{Generated lambda-native 1635}
> 1650} 1654} 1674) (foo) (list foo foo)) 2)
From the presence of lambda-native in the output, I presume you missed
the second half of my prescription:
> > You can drop this clause from the letrec-syntax bindings and
> > replace the one call to lambda-native with a call to lambda.
-al
### Joe Marshall
Mar 29, 2002, 7:06:00 AM3/29/02
to
"Thomas Bushnell, BSG" <[email protected]> wrote in message
news:[email protected]...
> [email protected] ([email protected]) writes:
>
> > If a Scheme system with defiled lambda and other binding forms
> > nevertheless complies with R5RS, it casts doubt on the assertion that
> > R5RS macros are referentially transparent.
>
> Hrm, I'm inclined to a holistic view of the standard. Such defiled
> lambdas, because they allow the violation of referential transparency,
> are not actually standard compliant.
Since they are implicitly allowed by the standard as is, then
they are standard compliant. So either the standard is incorrect
if it asserts that R5RS macros cannot be made ``referentially opaque''
(Oleg's view) or the standard is not standard compliant (Thomas
Bushnell, BSG's view). I think you are throwing out the baby
with the bathwater.
Whatever the case, I'm pleased that one can subvert the
hygiene of the pattern matching. This means that you do not
need to refer to an `underlying implementation' for those
cases where you don't want hygiene.
Now if someone could show how to go from non-hygienic
substitution to where you could execute arbitrary code
during macro expansion (ala DEFMACRO), then an
underlying implementation would not be necessary at all.
~jrm
### [email protected]
Apr 1, 2002, 4:02:29 PM4/1/02
to
Al Petrofsky <[email protected]> wrote in message news:<[email protected]>...
> The r5rs 4.3 discussion of the referential transparency of
> syntax-rules transformers states:
> * If a macro transformer inserts a free reference to an identifier,
> the reference refers to the binding that was visible where the
> transformer was specified, regardless of any local bindings that
> may surround the use of the macro.
This paragraph does apply as it is to the defiled macros. In the code,
(define foo 1)
(defile
(let ((foo 2)) (list (mm) foo))
)
the identifier 'foo' inserted in the expansion of the macro mm indeed
refers to the binding of 'foo' that was visible when macro 'mm' was
defined. The twist is that the definition of the macro 'mm' happened
right after the local binding of foo.
The macro 'defile' is a R5RS macro, in full compliance with R5RS.
The 'defile' macro shadows syntactic bindings and binds 'lambda',
'let', 'let*' in a local scope. That is not prohibited by R5RS.
R5RS states that there are no reserved keywords, and syntactic
bindings may shadow variable bindings and other syntactic bindings.
However, the result of the 'defile' expansion is observationally
equivalent to the expansion of a non-hygienic macro and is apparently
referentially opaque. That's the paradox: I go on following the rules
and end up seemingly contradicting them.
On one hand, I should not be surprised. The implementations of
lambda-calculator and of the Turing machine as R5RS macros prove that
the syntax-rules macros are Turing complete. Therefore, it is
potentially possible to use R5RS macros to build another macro system
that lacks the referential transparency guarantees.
This explanation leaves some sense of dissatisfaction. If I look at an
isolated peace of code, e.g.,
(let ((foo 2)) (list (mm) foo))
and know that macro mm expands into a reference to a variable foo
(which is also globally defined), I still can't tell which binding of
variable 'foo' will be captured. I cannot apply the referentially
transparency guarantee of R5RS because I don't know off hand if 'let'
or 'lambda' have been re-defined in _particular_ ways. To be sure
about the binding of 'foo', I have to analyze all the program up to
that point, check out definitions and re-definitions of all syntactic
keywords. Essentially I have to macro-expand a form in order to make
a judgment about its identifier bindings. The macro-expansion process
however, being Turing complete, may go on for a long time and may even
fail to terminate. This means that many simple judgments about
identifier bindings cannot be decided upon within bounded or
exponential etc. time -- cannot be mechanically decided, in general.
This conclusion poses another question. The R5RS macro system, being
severely constrained in expressiveness, is still powerful enough to
implement its own "negation", so to speak. If this behavior is deemed
acceptable, what is the reason then to keep the constraints? Why not
to add guards and other syntactic sugar of far more pleasant
syntax-case macros? If we have nothing to lose, we can at least enjoy
it.
### David Rush
Apr 3, 2002, 6:24:24 AM4/3/02
to
[email protected] ([email protected]) writes:
> On one hand, I should not be surprised. The implementations of
> lambda-calculator and of the Turing machine as R5RS macros prove that
> the syntax-rules macros are Turing complete. Therefore, it is
> potentially possible to use R5RS macros to build another macro system
> that lacks the referential transparency guarantees.
Yes. Isn't it amazing how hard it is to avoid Turing-completeness?
Your demonstration of macro-CPS raises some significant issues
w/rt the status of syntax-rules macros in R5RS.
> The R5RS macro system, being
> severely constrained in expressiveness, is still powerful enough to
> implement its own "negation", so to speak. If this behavior is deemed
> acceptable, what is the reason then to keep the constraints? Why not
> to add guards and other syntactic sugar of far more pleasant
> syntax-case macros? If we have nothing to lose, we can at least enjoy
> it.
As far as I'm concerned, all that's needed is for someone to turn the
syntax-case specification into a SRFI. Then, if there ever is an R6RS,
it can leave the macro system specification in the SRFI world, where
it belongs.
david rush
--
Censorship may be useful for preservation of morality, but can never
be so for its restoration.
-- Jean-Jacques Rousseau
|
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|
https://chemistry.stackexchange.com/questions/168054/why-would-a-reaction-be-nonspontaneous-at-higher-temperatures
|
# Why would a reaction be nonspontaneous at higher temperatures?
Typically we think of a higher temperature speeding up the reaction rate and/or supplying the activation energy of a reaction. So why is it the case that some reactions are only spontaneous at lower temperatures?
Using the gibbs free energy equation $$\Delta G = \Delta H - T \Delta S$$, If I have a reaction where $$\Delta H$$ is negative (exothermic?) and $$\Delta S$$ is negative it makes $$\Delta G$$ positive at higher temperatures which means the reaction is nonspontaneous at higher temperatures. Why would this be the case?
• LeChatelier's principle says a reaction that creates heat get's slower (and ultimately goes backwards) at higher temperature. And btw. it's totally arbitrary which one is the "forward" direction of any reaction.
– Karl
Sep 23, 2022 at 20:49
• @Karl Not slower, the net reaction ultimately is backwards. LeChatelier talks about equilibrium thermodynamics, not kinetics.
– Karsten
Sep 23, 2022 at 21:46
• @Karsten I agree, but Karl isn't completely wrong. If the equilibrium constant shifts, then the forward and backward rate constants do too (as $K = k_f/k_r$). A smaller equilibrium constant does indicate a slower forward reaction (and/or faster backward reaction). Sep 24, 2022 at 0:38
• You are mixing the thermodynamics and kinetics of a reaction, Thermodynamics just predicts if the reaction will happen or not, Kinetics predicts how fast will it happen, If the reaction is feasible then we look at its kinetics Oct 25, 2022 at 5:04
Thermodynamics studies systems at equilibrium so changing temperature moves the equilibrium from one position to another. For a given change we wish to know if the change of state will occur spontaneously or whether some amount of work is needed to make the change occur. In the gas phase this work usually called 'PV' work such as a change in volume. From the second law there must be overall entropy production so that the total change in entropy of the 'system' i.e. the reaction, plus that of the surroundings is always positive but which can be zero if the conditions are reversible. It can be shown using the First and Second Laws that the Gibbs free energy must decrease if the total entropy production is to be positive, i.e. the Gibbs free energy change must be negative for a spontaneous reaction.
When the temperature changes we can use the Van't Hoff Iscohore to predict what happens;
$$\frac{d\ln(K_p)}{dT}=\frac{\Delta H^{\text{o}}}{RT^2}$$
which when integrated (assuming that $$\Delta H^{\text{o}}$$ is independent of temperature over a small temp range which is often a good approximation) produces a gradient of $$-\Delta H^{\text{o}}/R$$ when $$\ln(K)$$ is plotted vs $$1/T$$.
(An aside. Notice that the entropy is not involved, the species involved are the same but in different proportions and there is always entropy of mixing which compensates. You can see this also from $$G=H-TS$$ where $$\displaystyle \left( \frac{\partial G}{\partial T} \right)_p = -S$$ is a constant as temperature changes.)
Thus for an exothermic reaction such as the formation of ammonia from hydrogen and nitrogen since $$\Delta H<0$$ the equilibrium constant $$K_p$$ must decrease as the temperature increases and less ammonia is in the equilibrium mixture as the temperature is increased, as is experimentally verified. The opposite is true for an endothermic reaction, i.e. dissociation of $$\ce{N_2O_4}$$.
If you have measured the forward and reverse rate constants, defining the equilibrium constant as the ratio of rate constants and using the Arrhenius equation produces
$$K_e= \frac{k_f}{k_b}=\frac{k_f^0}{k_b^0}e^{-(E_f-E_b)/RT}$$
where $$k_f, k_b$$ are the rate constants and $$E_f, E_b$$ the activation energies. An exothermic reaction has $$E_b > E_f$$ and the equilibrium constant decreases on increasing the temperature just as predicted by the thermodynamic argument.
Finally the Gibbs energy is related to the equilibrium constant as
$$\displaystyle \Delta G^{\text{o}}=-RT\ln(K_p)$$
so the sign of $$\Delta G^{\text{o}}$$, positive or negative, depends only on whether the equilibrium constant is less than or greater than one.
You expect both the forward and the reverse reaction to proceed faster at higher temperature. If the reverse reaction speeds up by a higher factor, this will affect the equilibrium.
"Spontaneous" is a technical term that does not reflect our day-to-day use of spontaneous. If you substitute the longer "goes forward or would have to go forward, starting from standard state, to attain equilibrium", it might make more sense.
If I start at standard state at a given temperature, either the forward reaction will be faster than the reverse reaction, or vice versa. If I repeat the experiment at higher temperature, I will see an increased forward rate and an increased reverse rate. These increases are typically not of the same magnitude, however.
So the direction that the reaction takes to reach equilibrium, starting from standard conditions, can be different depending on temperature. With respect to the direction of the reaction as written, it can change from spontaneous to non-spontaneous, or from non-spontaneous to spontaneous. If you write the reaction in the other direction, as Karl mentions, you come to the opposite conclusion.
In conclusion, there is always one net direction of the reaction that becomes "more favored", and the other net direction that becomes "less favored" as you increase the temperature and individual rates go up.
• Thank you for your answer. So basically what it means is that its opposite reaction would be favorable at the high temperature instead. Sep 24, 2022 at 17:11
• Yes, that is always the case. If a reaction is non-spontaneous, the reverse reaction is spontaneous. It just says that equilibrium is either reached in the forward or the reverse direction (unless we are already at equilibrium, in which case we don't see any net reaction).
– Karsten
Sep 24, 2022 at 17:38
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|
https://physics.stackexchange.com/questions/616149/amperian-loop-and-magnetic-field
|
# Amperian loop and magnetic field
Suppose I have a long solenoid with $$n$$ turns per unit length. The current through the solenoid is changing and I am interested in finding the magnetic field $$(B)$$ inside. So, we choose an amperian path as in this figure and equate $$\oint B.dl= \mu_0\times nli$$ $$\Rightarrow B = \mu_0\times ni$$ and then differentiating wrt. time and using $$\oint E_{induced}.dl= -\frac{d\phi}{dt}$$ we get the E field at a distance $$r$$ from the centre of the loop equals $$\dfrac{\mu_0\times nr}{2}\times \dfrac{di}{dt}$$. And in the very first step of choosing amperian path, we have an extra term $$\mu_0\epsilon_0 \dfrac{d\phi_E}{dt}$$ which depends upon the second time derivative of current. So, why is this term ignored in the derivation.
That therm comes from the fact that in the vacumm $$i$$ needs to be seen as $$i_{tot} = i + \epsilon_o \frac{d \phi_E}{dt}$$ (for more in depht view you can search "displacement current" on wikipedia), which acconts for the current not being costant in time in the ampere's law (to be precise all the discussion is made around the 4th maxwell equation, which is basically the non-integral version of ampere's law).
$$$$\int B u_n d\Sigma = \mu_oi_{tot} = \mu_oi + \mu_o\epsilon_o \frac{d \phi_E}{dt}$$$$
Most of the time the displacement current can be considered negligible (and $$\epsilon_o$$ is very small in comparison to $$i$$) and you case this term can be ignored.
• yes the final result shoud be the same. But you can just not consider the displacement currenti from the beggining being 10^8 times smaller than $\mu_oi$ (you don't need to "demostrate" an approsimation like that, it's simply common sense) – lorenzo Baldessarini Feb 21 at 14:58
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http://poincare101.blogspot.com/2011/11/abstract-algebra-presented-in-non.html
|
## Sunday, November 27, 2011
### Abstract Algebra presented in a non-intimidating way (esp. for developers)
Hi.
I think math is really cool, but, most people (sadly) don't think so. This includes many programmers who in fact enjoy many of the same things that mathematicians do, but, are more practical for most of the time.
I'll show you why abstract algebra (in particular, group theory) is really cool, and why you don't have to be a freaking genius to get it.
Firstly, in order to understand most of this, you'll need to understand a tiny bit of Set theory, and to save time, I'll just refer you to wikipedia for that one (you just need to understand basic unions and intersections).
Let's begin with a simple definition, of a group (note: for hardcore types, this isn't fully rigorous because I haven't defined what an operation is, but, you get the idea).
A group is defined:
1)
A set (usually called $S$) with an operation attached (we call the operation $*$), so, if $G$ is a group,
$G = <S, *>$
2) Closure is one property that all groups must have in order for them to be a group. Closure means:
If $G = <S, *>$ and $x \epsilon S$ and $y \epsilon S$, then $x*y \epsilon S$
Note: $*$ does NOT NECESSARILY MEAN MULTIPLICATION!
3)
All groups have an identity element $e$, such that ( we are still considering the group $G$ with operation $*$):
For all $x \epsilon S$, $x*e = x$
4)
All elements in a group have an inverse,
If $a \epsilon S$, $a^{-1} \epsilon S$ such that:
$a * a^{-1} = e$
5)
The operation $*$ is associative. That means:
$(a*b)*c = a*(b*c)$
Alright, why in the world would anyone in their right mind define something like that?!
Let's take a step back, and understand where this comes from.
Around the 19th century or so, people realized that elementary algebra wasn't the only type of algebra that existed. There were all kinds of other algebras, like matrix algebra, and vector algebra and boolean algebra, and all these new all these new kinds of algebras kept cropping up with all these new rules (like, matrix multplication isn't commutative, that means: $A*B$ is not necessarily equal to $B*A$ when $B$ and $A$ are matrices) because mathematicians now had to solve all kinds of new problems.
And, the problem was, mathematics was losing its "connectivity", all these new algebras had little to no connection to each other, and it was very difficult to make progress in a few of these algebras at once.
Then, there was a clever idea. All of these algebras still were only doing a few operations on a set (or crossproducts of sets) and then were equating those operations on sets. That's how abstract algebra came along. Mathematicians realized that they could define "algebraic structures" (i.e. define algebraic systems so they followed a few axioms), and prove things about those algebraic structures, and any algebra that was then invented that could be proven to fit that algebraic structure would automatically have all the properties that people had proved about those structures!
Basically, if you came up with a new algebra, called "Cheese Algebra" and it has all these funny rules, but, it handles only one operation and you can prove that Cheese Algebra has all the properties of a Group, you're done! That means that all the things people have proven for Groups are automatically true for Cheese Algebra!
Isn't that awesome?
Let's try it.
The definition of a group is pretty simple, but, there are a few catches. First and foremost, the $*$ operation is not multiplication. Read the sentence over again. And again.
Secondly, in a group $a*b$ is not necessarily equal to $b*a$. Groups in which this is true are called Abelian groups and they make your life much easier, but, not all groups are like that.
Then, there are some basic theorems about groups that can be proven, and these are some important ones:
• A group has a single, unique identity element
• Every element of a group has a single, unique inverse
• $(a_1*a_2*a_3* ... * a_n)^ {-1} = (a_n^{-1} * a_{n-1}^{-1} * a_{n-2}^{-1} * ... * a_1^{-1})$
• $(a^{-1})^{-1} = a$
Let's prove a couple of them.
The first one is pretty easy, we assume there are two identities, $e_1$ and $e_2$ for a group $G = <S, *>$ and this would mean,
$e_1*e_2 = e_1$ (consider $e_2$ as the identity element)
$e_1*e_2 = e_2$ (consider $e_1$ as the identity element)
Which means $e_1=e_2$, which is a contradiction.
The second one is really similar, so, I won't go into the details.
The third one is a bit different, you first prove $(a*b)^-1 = b^{-1} * a^{-1}$ and then use the associative property of groups.
Okay, so, what does this mean?
Well, each of these properties hold for every algebraic system that's a group!
So, for example, matrices (the ones that do have inverses) form a group under the operation of multiplication, so, we've figured out a bunch of cool properties about matrices, like
The inverse of the inverse of a matrix is the matrix itself.
And, we haven't dealt with a single $a_ij$ component (although we would in proving that "inverseable" matrices do indeed form a group under multiplication)!
Also, the real numbers (excluding zero) form a group under multiplication, so, we can say this, too,
The reciprocal of the recipocral of a real number is the real number itself.
And, vectors form a group under addition (this one's really easy to prove, I suggest you try with the axioms given, hint: the identity is the vector <0,0,0>), too:
If you negate the negative of a vector, you get the vector itself.
Notice that the inverse operations change with each of them, but, the idea is still the same, so, with the single idea of a group, we've solved problems in a bunch of different areas of mathematics.
Let's try something a bit more complex, let's solve an equation on a group. What does that mean? Well, we can't use our knowledge of existing algebra, we can only use the axioms about groups, and the things we proved from them in order to solve the equation.
Now, I'll show you the equation, but, try solving it first if you can before looking at the solution, it'll give you a different kind of appreciation for the solution.
Solve the equation $a*x*b = c$ for $x$ in terms of $a, b, c$, which are constants.
Solution
=======
Multiply both sides by $b^{-1}$,
$a*x*b*b^{-1} = c*b^{-1}$
Since $b*b^{-1} = e$,
$a*x*e = c*b^{-1}$
Since, $a*x*e = (a*x)*e = a*x$,
$a*x = c*b^{-1}$
Now, since each element of the group has a unique inverse, we can take the inverse of both sides of the equation, and the equation will still hold true:
$(a*x)^-1 = (c*b^{-1})^{-1}$
Which is the same as:
$x^{-1}*a^{-1} = b*c^{-1}$
Multiply both sides by $a$,
$x^{-1} = b*c^{-1}*a$
Take the inverse of both sides again, and notcie $(a^{-1})^{-1}$,
$x = a^{-1}*c*b^{-1}$
Yay!
Now, what's (again) really cool, is that this works for every, single freaking algebraic system that you can think of that's a group. Matrices with multiplication? Done. Real numbers with multiplication (aside from 0)? Done. Vectors with addition? Done.
Abstract algebra doesn't stop there, it defines all these structures that have similar properties like Rings and Fields that you can use to prove things in a bunch of different algebras in one fell swoop.
I hope you liked this article, and I'd love your feedback, email me at dhaivatpandya at g mail dot com, or comment below :)
EDIT: I forgot to mention some applications to CS.
Alright, you guys know how Haskell?
Haskell (and any ML-type language, really) uses something known as Algebraic data types, which basically let you specify datatypes that follow certain axioms, in a way.
Even though it is completely your responsibility to make sure that these structures form some kind of helpful algebra, the relation is still there.
And, about classes in OOP languages, there's a very close correlation.
You can very nearly think of classes as a algebraic structure that have many operations (methods) and elements (fields, variables, etc.), but, this isn't a perfect correlation because of many things that OOP languages let you do that are functionally "impure", and mathematics is a completely pure functional language (which is why it maps to Haskell so nicely), there is no state.
1. You lost me right after "The first one is pretty easy".
Why are there two identities when there should only be one? And what is an identity anyway? A number? Why is e1 = e2 a contradiction?
Why is the second theorem really similar? In what way is it similar?
For theorem #4, What is that "1" with the upper bar in front of it? Is that supposed to be an equals?
"The inverse of the inverse of a matrix is the matrix itself." I don't get where this conclusion is coming from.
The rest of it requires knowledge from before, so I'm completely lost at this point.
1. Groups are invented for a different purpose. I hate the theorem, proof approach. One has to be present with the problem, and then tools to solve them. Groups have at least 300 years of history. One the most important, easy and beautiful tools of math.
Now to your question. The statement should begin like this " we assume there are two identities, e1 and e2 for a group G=, and e_1 <> e_2 and this would mean" e_1 <> e_2 was missing.
But again, you don't learn math in blog comments. ;)
2. Its pretty hard to come up with a problem that people can relate to easily when working with something like group theory, but, I have tried that approach in newer posts.
Thanks a lot for the feedback!
Do follow (top right) if you like it :)
2. You present a very clear introduction to algebra here, which is much more accessible than, say, the relevant wikipedia articles. You keep it nice and simple and to the point.
For math geeks, I think this is great -- you start off with some definitions, then a little history, and then start to show the power of this abstract concept. I imagine that you'd follow this up with some practical uses (e.g. computer graphics).
I'm worried that for computer engineers, and to a lesser extent computer scientists, this may still be too abstract. I recall several math courses starting off this way, with definitions, some history, then looking at properties and deriving interesting theorems. Maybe it would be possible to motivate the power of group theory by starting with a problem in computer science and describing how an understanding of group theory can lead to a better understanding of the problem and solution? I'm thinking of something like quaternions and understanding how they interact (without needing to deal with imaginary numbers). I'm sure you know many more interesting problems in computer science and engineering, and I can't wait to read more about them.
3. Wolter:
The contradiction occurs because we assumed that it had two different identities, but, they turn out to be the same, which means that there is only one identity per group.
The second theorem is very similar because it requires that you use the same idea as the first:
i.e. Assume $a$ has two inverse $a^{-1}_1$ and $a^{-1}_2$, and then we know:
$a * a^{-1}_1 = e = a * a^{-1}_2$
Therefore,
$a^{-1}_1 = a^{-1}_2$
As for the Theorem #4 question, that was a fault in my part, its supposed to mean:
$(a^{-1})^{-1}$
And the matrix conclusion is coming from the fact that matrix multiplication is forms a group,
so, if you have a matrix $M$, then:
$(M^{-1})^{-1} = M$
by Theorem #4.
@coshx
Thanks a lot for the feedback! I will be doing more stuff on this considering the postive feedback I've gotten, and I will be doing more applications, but, as always, applications are slightly more difficult to understand than just pure math, so, I'll be presenting a proper application in the next one (which will probably introduce Rings as well).
4. Dhaivat,
Thanks for your post. It lost me about halfway through. I may try again in the morning when I'm rested. You say that applications are more difficult to understand than pure math. If you're talking about programming applications, they may be slightly more difficult for you, but for most of us, the pure math is more difficult, which is why we became programmers and not mathmaticians. If you're specifically targeting programmers, then starting off with a practical application, even one involving a language that not many programmers know, such as Haskell (I'm learning it now), would be extremely beneficial.
5. The thing is, with group theory, a subject so abstract, a very practical matter would be more difficult to understand than the pure math because most practical applications require a strong understanding of group theory (isomorphisms, rings, fields, etc.), that's why I refrained from using practical applications. But, with the next one, I assure you there'll be much more practical stuff :)
If you're getting stuck with it, try going slow, group theory is very abstract subject, so taking it slow would be best :)
If are still having trouble, contact me on dhaivatpandya AT gmail DOT com, my twitter at dhaivatpoincare, or just leave a comment here, I'll do my best to help :)
6. Hey Dhaivat,
This is a bit nit-picky, but...
Your definition of an "identity" element is not quite right:
>"All groups have an identity element e, such that:
For all xϵS, x∗e=x"
This is a right-identity. It's also important that e is a left-identity as well for it to be an "identity".
i.e. For all xϵS, e*x=x
Your later proof shows that if there is a left identity and a right identity, they must be equal (and therefore unique).
Basically there are three statements which are equivalent:
A) The set has at least one left identity and at least one right identity (not necessarily the same).
B) The set has at least one element which is both a left and a right identity.
C) The set has exactly one element which is both a left identity and a right identity.
I don't think it matters which one you take as the definition, and which one you later prove the equivalence of.
7. Hi Dhaivat,
Your explanation is fantastically good. You are brilliant at exposing concepts that are not necessarily easy to understand. I hope you will write many more such articles, because they are truly refreshing.
I have been looking for articles such as yours, that clarify with real examples and exercises, how to compute LALR1 lookahead sets in the presence of numerous epsilon rules, and how to understand the results intuitively. Unfortunately, nobody in that area seems to have pen as good as yours ...
8. Your definition of an identity element is incomplete. You also need that if e is the identity element, e * x = x for all x in S (for example, to prove that there can be only one identity element).
Without this, I could define S to be the reals, and the * operation to be an identity operation, so that x * y = x for all x, y in S. This is obviously not a group, but it satisfies your definition.
9. "The contradiction occurs because we assumed that it had two different identities, but, they turn out to be the same"
So if e1 turned out to be "1" and e2 turned out to be "2", then 1 = 2? Is that the contradiction?
"(a−1)−1"
But what does that mean? There's no equals sign in there anywhere.
Also, looking further ahead, why not just multiply both sides by a-1 and then multiply by b-1 to get x = a-1 * c * b-1? It seems like all the other steps just complicate things.
10. On a related note, proving inverses to be unique (your second theorem) is perhaps similar to proving the identity unique (your first theorem), but you should probably mention that you first have to prove that a * a^-1 = e implies a^-1 * a = e (this follows from the uniqueness of the identity element and some fiddling with associativity).
11. @Jeremy: I have read about left and right identities, but, I sort of left them out for the sake of decreasing complexity, but, they do leave a small hole, yes.
@Erik
Thanks for your feedback, its really encouraging. I will be covering more and more stuff, so, stay tuned.
@Alex
See what I said to Jeremy. Basically, I'm trading complete rigor for a more understandable idea.
@Wolter
No, no see, $e_1$ and $e_2$ were assumed to be *different* identity elements, but it turns out that they are in fact the same, so, we can only have one identity element $e$, so, there's no question of $e_2=2$ and $e_1=1$ because they're the same, and we assumed that they were different.
(a-1)-1 isn't what it says, it says $(a^{-1})^{-1}$
Where $a^{-1}$ is the inverse of $a$ such that:
$a * a^{-1} = e$
And, for your last question, you can't do that since you would be assuming that the * operation is commutative which isn't necessarily true.
Hopefully that made sense, if it didn't, I'm still awake for another hour :)
12. I understand your comments about rigor, and maybe I will include most things in the next one, but, I really wanted this one to be understandable to all audiences and not to be bogged down into details.
However, I did miss the
$a*e = a = e*a$
which should have been mentioned.
13. So how do you decide what the identity element is?
Also, I thought multiplication was commutative?
14. Oh almost forgot. I wrote (a-1)-1 this way because that's how it copy/pastes. But I still don't understand what it's supposed to means since there's no equals in there.
15. @Wolter
Multiplication is commutative, but, the * operand just represents a generic operation, not necessarily multiplication.
The identity element is usually found using some ideas of the set and operation you're considering.
Like, if you're consider integers as your set, and addition as your operation, your identity element would be 0, since any integer + 0 = that integer.
And, for the $(a^{-1})^{-1}$, it was my mistake again, I'm sorry I didn't understand you earlier, now its fixed, you should go look :)
16. I like your post. It seems the definition of a group you give is very similar to the definition of Monoids in Haskell or Scala (aka type theory). As a matter of fact, as currently learning about it, application of monoids can lead to very useful code patterns like unfolding data in tree structures (nodes in the trees being seen as context holding data values). Thank you for sharing.
17. yes, since mathematics is a purely functional language, languages like haskell, scala (even clojure to some extent) map very nicely to it, and especially group theory since functional programming languages can be a special type of algebra.
18. "Multiplication is commutative, but, the * operand just represents a generic operation, not necessarily multiplication."
Ok, but in your example, you're saying to multiply both sides, so isn't it multiplication in this case?
"Like, if you're consider integers as your set, and addition as your operation, your identity element would be 0, since any integer + 0 = that integer."
OK, so if you were to assume that 0 and 1 were identity elements in this case, then 0 = 1 would be the contradiction?
19. No, i'm not multiplying, I'm just using the operand * on both sides (its called the multiplicative operand, but its got nothing to do with multiplication
No, 0 and 1 are not the identity elements, only 0 is the identity element. Because if you take any number, say 6 and add 1 to it, you don't get 6 back, you get 7, so, 1 is not the identity element.
20. But in your example, you say "Multiply both sides by b−1"...
"No, 0 and 1 are not the identity elements, only 0 is the identity element."
Yes, I understand this, but I'm talking about the assumption of 2 identity elements as you stated before: "e1 * e2 = e1" and "e1 * e2 = e2", thus e1 = e2. But if you chose 0 and 1 as your assumed identity elements that would mean 0 = 1... Is that what you mean by the contradiction?
21. I say "multiply both sides by" because the * is called the multiplicative operand, even though its got nothing to do with multiplication (that's really stupid, I know, but that's the way it works)
22. Fair enough.
So partway through the example you end up with "a∗x=c∗b−1". From there, why can't you just multiply both sides by a-1?
23. Because a*x*a^(-1) != a*a^(-1)*x
24. It's wonderful to see 14 year old write about math, especially with some actual background story to go along with it, but I feel like you're missing your audience (if you aim to reach programmers). For example, you state that proving things about abstract algebras is great, but fail to give any concrete examples beyond "it's neat".
And rather than ground it by starting from a known quality (i.e. an algebra people know), you explicitly dive in with things like "* is not multiplication!", and make it sound very important, without answering the next thought 95% of your readers will have: "then what is it?" i.e. The reader should be able to build up a concrete picture of what you're describing so they can reason about it, not have to take your word for things.
Do keep writing and teaching, but try to be more aware that everyone approaches topics from their own perspective, and you need to cover all bases. Your opening problem, that many people don't think math is cool, is mostly due to the fact that math is taught in the same way everywhere, by the book, and starting from formulas that, taken at face value, are meaningless runes carved in stone, when they actually represent things that we can easily grasp with our mind: lines, curves, quantities, sets, orientations, topologies, etc. A gifted mathematician loves abstraction so that they will quickly build up their own picture and relish the chance to abstract it. Most people however need stuff that's grounded in the familiar.
25. I should add this link, as it's one of the best reads I've ever had on the topic of math, and teaching it:
http://www.maa.org/devlin/LockhartsLament.pdf
26. Wolter, just in case, here's how I understand your original question:
"Why are there two identities when there should only be one?"
There isn't - its a proof through contradiction. That is, you assume the opposite of what you want to prove (in this case the opposite of "there is only one identity") and prove that this cannot be possible because it would be a contradiction.
"And what is an identity anyway?"
An identity is an element of the set in question. So, if your set is a set of numbers, then yes, its a number. If you're working with a set of vectors, then the identity is a vector. If a set of apples existed where some operation on this set were to form a group, then the identity would be an apple. For something to be an identity it simply needs to meet the rule that x op e = x, where x is any element of your set, op is the operation of the group and e is the identity.
"Why is e1 = e2 a contradiction?"
He is proving that a group with two (or more) identities is a contradiction. To prove this he takes any two (different - if he took two that are actually the same, then he is not proving that a group can or cant have more than one identity, since he is only working with one!) identities and shows that it would only be possible if they were the same. But if they're the same then he didn't really pick two identities at all - he only picked one - therefore the setup of two identities is a contradiction. This means that a group with two or more identities cannot exist.
27. We probably need to include the axiom "e * x = x" for proving identity element uniqueness.
28. Dan: That makes a lot more sense. So can you explain why you can multiply both sides of "a∗x∗b=c" by b-1, but you can't multiply "a∗x=c∗b−1" by a-1? All he said is "a*x*a^(-1) != a*a^(-1)*x", which doesn't mean anything to me.
29. Wolter, let me show you why your idea of multiplying both sides doesn't quite work (though with the traditional definition of a group, for example from wikipedia, it does):
You are at the step where you have a ∗ x = c ∗ b^−1.
From this, it follows that a^-1 * (a * x) = a^-1 * (c * b^-1). By associativity, this means that (a^-1 * a) * x = a^-1 * c * b^-1.
Now we are almost there. If we knew that a^-1 * a = e then we could substitute that fact in and get the final answer. But we never actually proved that. Our axiom about inverses never stated that a^-1 * a = e when a^-1 and a are written in this opposite order. This is actually a true fact, but you would need more steps to prove it.
By the way, the wikipedia definition includes this fact as an axiom, which is defining slightly more than you need. You need either e * a = a * e = e, or a^-1 * a = a * a^-1 = e. If either of these properties hold for a group, you can derive the other.
30. @Steven
A lot of people have told me similar things, I will really try to include more applications in the next one, but, in such basic group theory, it is very difficult to have any real applications, because they all require atleast some idea of what groups are and how they're used.
BTW, I love the Lockhart's Lament :)
@Wolter and Steven
Stupid commutativity. Screws it up for everyone.
31. "And, about classes in OOP languages, there's a very close correlation."
This is utter nonsense. Object orientation isn't even one thing - it's two things (the Kay style Smalltalk message passing between interfaces mindset or the C++ compile-time virtual pointer table abstraction to call interfaces.)
You're just saying "oh, and these two things are similar."
They're not even remotely similar. The math you're talking about is about proving properties. Object orientation outside ML/Coq is not provable in any meaningful way, and the purpose of OOP is not to show proof. OOP in both cases are about decomposing complex systems into simpler systems so that they're easier to reason about and maintain.
The stunningly obvious nonsensical nature of this claim throws the rest of the article into doubt.
32. Did you read the explanation why I thought they were similar?
I said that it was absolutely up to the writer of the classes that they formed any sort of algebraic structure, but, the idea is there. You're taking elements (data), and you're defining operations on them, which is the exact point of algebraic systems.
I'm not sure if that's what you understood, and still gave that response, and if that's the case, it would be better if you could explain why "The math you're talking about is about proving properties"
33. Dhaivat: the thing is, every lesson should start with a light bulb going off that says "Isn't that interesting?". If you look at your post, you chose to start with "a simple definition" that is actually 5 separate definitions full of 'math words' and symbols.
If you want to illustrate the universality of these rules, you should at the very least show how they work in concrete, familiar groups, e.g. integers, matrices, modular arithmetic, ... That way, you can show and convince your reader that there is a universal pattern, rather than telling them.
Also, if you like Lockhart's Lament, go seek out texts and videos by Richard Feynman, arguably one of the greatest teachers of the last century. But he may convince you to become a physicist instead of a mathematician ;).
34. Yeah, that makes sense. BTW, my next one most likely won't be out until Saturday; I have a lot of stuff going on.
I like Richard Feynman as well :) I've read all the "Lectures in Physics" books he has, they're really excellent, he starts out with simple observations and turns them into a complete study.
35. Im a programmer, I read your article 5 times, still couldn't understand diddly dime squat,.. I started reading up on SET theory (the wiki).. Didnt understand squat there as well, tried to read up on the closure property of SETS,.. nope no luck there.... tried to understand what an axiom is, dont get me started, Tried everything... sniff, I give up.. I wish I can understand it all.. Cant call myself a coder till then..
36. Rohit,
Okay, can you tell me roughly where you start getting lost?
An axiom (don't look this up on Wikipedia; it'll sound like meaningless junk) means something you assume in order to prove other things. Like, in Geometry, you assume that the shortest distance between two points is a line.
37. Dhaivat, I start getting lost when you say G=. So A group Is a Set and an operation. I assume that an operation is a something like a union or intersection. So I start to wonder, dont you need two sets to complete an operation ? So whats with the comma and the prompt signs ?.. Sorry im sounding too new. Okay when you say xϵS, what does the "ϵ" mean ? its like a "belongs to".. I Can't figure. And when you say "inverse" of a group. I cant figure what. I remember in school, we learnt "matrices" and how to form an inverse of them. The thing is we never learnt what is matrix is and where it is applied.. We were just thought that, "this is the way to invert a matrix". No now when Im free from previous conditioning, Im begining to question every little small thing, I cant go through the full article when I have doubts at every single line. I only have myself to blame, Im giving your article another shot, this time, Im reading up on SETS, Matrices, algebra again. Thanks man, From the other comments, everyone thinks this is an awesome read. I wish i could be there too
38. Okay, I see where your problem is.
Firstly, you only need one set ($S$), because you can have two elements from $S$, like $x$ and $y$, and perform the operation $*$ on them to get $x*y$. Does that make sense so far?
The $x \epsilon S$ means $x$ is a member of the set $S$.
See if you can understand anything from that.
And, I've had that exact same problem with matrices (even though aren't related to this subject in particular), and mostly, school math is a load of BS.
39. Nice post ,Best Mobile Phone Solutions says I read your post many times but I never understand what you exactly want to say .So can you explain in which step you are facing problem.
40. Your last proof could be much shorter if you went on and said that $a^{-1} \ast a \ast x = a^{-1} \ast c \ast b^{-1}$. The reason this works is trivial: you are effectively doing $a^{-1} \ast (a \ast x) = a^{-1} \ast (a \ast x)$, then performing a substitution.
Perhaps this was what another poster attempted to point out.
41. Yeah, that's true.
Thanks a lot for the input!
42. Hi Dhaivat,
thanks for the article.
I have one suggestion, though I don't know if it makes sense.
Since you are targeting programmers maybe you could use some programming metaphores like explaining an abstract operation with operator overloading or xϵS is like S is a class x,y are objects.
This may be not totally true but could help getting an idea.
Cheers,
Ramon
43. Hi!
Nice Post. I've never looked at algebra like this. Thanks.
44. Thanks :)
45. I just want to say your post is tremendous. The clarity in your post is simply spectacular and i can assume you are an expert on this field.
travel to Egypt
1. Thanks.
I'm actually a student.
46. This comment has been removed by a blog administrator.
1. Would you like to leave? Thanks.
47. Algebra is a major component of math that is used to unify mathematic concepts. Algebra is built on experiences with numbers and operations, along with geometry and data analysis. Some students think that algebra is like learning another language. This is true to a small extent, algebra is a simple language used to solve problems that can not be solved by numbers alone. It models real-world situations by using symbols, such as the letters x, y, and z to represent numbers.
simplify the expression
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https://socratic.org/questions/5a1e07a47c014958fb5cc9f3#512981
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Precalculus
Topics
# Question #cc9f3
Nov 29, 2017
It's an even function.
#### Explanation:
A function is odd $f \left(- x\right) = - f \left(x\right)$
A function is even if $f \left(- x\right) = f \left(x\right)$
In this problem substitute $f \left(- x\right)$ so,
$f \left(- x\right) = {\left(- x\right)}^{4} - 3 {\left(- x\right)}^{2} - 4$
$= {x}^{4} - 3 {x}^{2} - 4$
When we substitute $- x$, we get the original function therefore, this is an even function.
##### Impact of this question
302 views around the world
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http://mfat.imath.kiev.ua/article/?id=984
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Open Access
# Transformations of Nevanlinna operator-functions and their fixed points
### Abstract
We give a new characterization of the class ${\bf N}^0_{\mathfrak M}[-1,1]$ of the operator-valued in the Hilbert space ${\mathfrak M}$ Nevanlinna functions that admit representations as compressed resolvents ($m$-functions) of selfadjoint contractions. We consider the auto\-morphism ${\bf \Gamma}:$ $M(\lambda){\mapsto}M_{{\bf \Gamma}} (\lambda):=\left((\lambda^2-1)M(\lambda)\right)^{-1}$ of the class ${\bf N}^0_{\mathfrak M}[-1,1]$ and construct a realization of $M_{{\bf \Gamma}}(\lambda)$ as a compressed resolvent. The unique fixed point of ${\bf\Gamma}$ is the $m$-function of the block-operator Jacobi matrix related to the Chebyshev polynomials of the first kind. We study a transformation ${\bf\widehat \Gamma}:$ ${\mathcal M}(\lambda)\mapsto {\mathcal M}_{{\bf\widehat \Gamma}}(\lambda) :=-({\mathcal M}(\lambda)+\lambda I_{\mathfrak M})^{-1}$ that maps the set of all Nevanlinna operator-valued functions into its subset. The unique fixed point ${\mathcal M}_0$ of ${\bf\widehat \Gamma}$ admits a realization as the compressed resolvent of the "free" discrete Schrödinger operator ${\bf\widehat J}_0$ in the Hilbert space ${\bf H}_0=\ell^2({\mathbb N}_0)\bigotimes{\mathfrak M}$. We prove that ${\mathcal M}_0$ is the uniform limit on compact sets of the open upper/lower half-plane in the operator norm topology of the iterations $\{{\mathcal M}_{n+1}(\lambda)=-({\mathcal M}_n(\lambda)+\lambda I_{\mathfrak M})^{-1}\}$ of ${\bf\widehat\Gamma}$. We show that the pair $\{{\bf H}_0,{\bf \widehat J}_0\}$ is the inductive limit of the sequence of realizations $\{\widehat{\mathfrak H}_n,\widehat A_n\}$ of $\{{\mathcal M}_n\}$. In the scalar case $({\mathfrak M}={\mathbb C})$, applying the algorithm of I.S. Kac, a realization of iterates $\{{\mathcal M}_n(\lambda)\}$ as $m$-functions of canonical (Hamiltonian) systems is constructed.
Key words: Nevanlinna operator-valued function, compressed resolvent, fixed point, block-operator Jacobi matrix, canonical system.
### Article Information
Title Transformations of Nevanlinna operator-functions and their fixed points Source Methods Funct. Anal. Topology, Vol. 23 (2017), no. 3, 212-230 Milestones Received 19/04/2017; Revised 30/05/2017 Copyright The Author(s) 2017 (CC BY-SA)
### Authors Information
Yu. M. Arlinskiĭ
Department of Mathematics, Dragomanov National Pedagogical University, 9 Pirogova, Kyiv, 01601, Ukraine
### Citation Example
Yu. M. Arlinskiĭ, Transformations of Nevanlinna operator-functions and their fixed points, Methods Funct. Anal. Topology 23 (2017), no. 3, 212-230.
### BibTex
@article {MFAT984,
AUTHOR = {Arlinskiĭ, Yu. M.},
TITLE = {Transformations of Nevanlinna operator-functions and their fixed points},
JOURNAL = {Methods Funct. Anal. Topology},
FJOURNAL = {Methods of Functional Analysis and Topology},
VOLUME = {23},
YEAR = {2017},
NUMBER = {3},
PAGES = {212-230},
ISSN = {1029-3531},
URL = {http://mfat.imath.kiev.ua/article/?id=984},
}
Coming Soon.
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https://www.cut-the-knot.org/do_you_know/Buratino1.shtml
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# Golden Ratio in Square
Tran Quang Hung has posted on the CutTheKnotMath facebook page a simple construction of the golden ratio.
### Construction
In square $ABCD$ $M,N,P,Q$ are midpoints of the sides, as shown below; $F$ the center of the square. Then circle $(AP)$ on $AP$ as a diameter, cuts $NF$ (point $X$) in Golden Ratio. Chord $AX$ cuts $MF$ in Golden Ratio:
Then $\displaystyle\frac{FX}{NX}=\frac{MZ}{FZ}=\phi,$ the golden ratio.
### Proof
Assume, without loss of generality, that $AB=2.$ Then $AP=\sqrt{5}.$ Since $AP$ is a diameter of the circle, $E$ - the intersection of $AP$ and $NQ$ is its center, which shows that $EX=\frac{1}{2}\sqrt{5}$ and that $EF=\frac{1}{2}.$ It follows that $FX=\frac{1}{2}(\sqrt{5}-1)$ and $NX=1-FX=\frac{1}{2}(3-\sqrt{5}),$ with a consequence that $\displaystyle\frac{FX}{NX}=\frac{1+\sqrt{5}}{2}=\phi.$
Next, triangles $AQX$ and $ZFX$ are similar: $\displaystyle\frac{FZ}{AQ}=\frac{FX}{QX},$ implying
$\displaystyle FZ=\frac{FX}{FX+1}=\frac{\sqrt{5}-1}{\sqrt{5}+1}=NX.$
We thus also have $MZ=FX$ and $\displaystyle\frac{MZ}{FZ}=\frac{FX}{NX}=\phi.$
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https://waseda.pure.elsevier.com/ja/publications/a-numerical-proof-algorithm-for-the-non-existence-of-solutions-to
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# A numerical proof algorithm for the non-existence of solutions to elliptic boundary value problems
Kouta Sekine*, Mitsuhiro T. Nakao, Shin'ichi Oishi, Masahide Kashiwagi
*この研究の対応する著者
## 抄録
In 1988, M.T. Nakao developed an algorithm that was based on the fixed-point theorem on Sobolev spaces for the numerical proof of the existence of solutions to elliptic boundary value problems on a bounded domain with a Lipschitz boundary (Nakao (1988) [9]). Thereafter, many researchers reported that the numerical existence proof algorithm to elliptic boundary value problems is actually significant and sufficiently useful. However, the numerical proof of the non-existence of solutions to the problem has hitherto not been considered due to several challenges. The purpose of this paper is to solve these difficulties and to propose an algorithm for the numerical proof of the non-existence of solutions in a closed ball B¯H01(uˆ,ρ)={u∈H01(Ω)|‖u−uˆ‖H01≤ρ} to elliptic boundary value problems. We demonstrate some numerical examples that confirm the usefulness of the proposed algorithm.
本文言語 English 87-107 21 Applied Numerical Mathematics 169 https://doi.org/10.1016/j.apnum.2021.06.011 Published - 2021 11
• 数値解析
• 計算数学
• 応用数学
## フィンガープリント
「A numerical proof algorithm for the non-existence of solutions to elliptic boundary value problems」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。
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http://link.springer.com/article/10.1007%2Fs00122-007-0512-6
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, Volume 114, Issue 7, pp 1211-1228
# QTL mapping with near-isogenic lines in maize
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## Abstract
A set of 89 near-isogenic lines (NILs) of maize was created using marker-assisted selection. Nineteen genomic regions, identified by restriction fragment length polymorphism loci and chosen to represent portions of all ten maize chromosomes, were introgressed by backcrossing three generations from donor line Tx303 into the B73 genetic background. NILs were genotyped at an additional 128 simple sequence repeat loci to estimate the size of introgressions and the amount of background introgression. Tx303 introgressions ranged in size from 10 to 150 cM, with an average of 60 cM. Across all NILs, 89% of the Tx303 genome is represented in targeted and background introgressions. The average proportion of background introgression was 2.5% (range 0–15%), significantly lower than the expected value of 9.4% for third backcross generation lines developed without marker-assisted selection. The NILs were grown in replicated field evaluations in two years to map QTLs for flowering time traits. A parallel experiment of testcrosses of each NIL to the unrelated inbred, Mo17, was conducted in the same environments to map QTLs in NIL testcross hybrids. QTLs affecting days to anthesis, days to silking, and anthesis-silk interval were detected in both inbreds and hybrids in both environments. The testing environments differed dramatically for drought stress, and different sets of QTLs were detected across environments. Furthermore, QTLs detected in inbreds were typically different from QTLs detected in hybrids, demonstrating the genetic complexity of flowering time. NILs can serve as a valuable genetic mapping resource for maize breeders and geneticists.
Communicated by M. Bohn.
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https://aimsciences.org/article/doi/10.3934/cpaa.2015.14.941
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# American Institute of Mathematical Sciences
May 2015, 14(3): 941-957. doi: 10.3934/cpaa.2015.14.941
## KAM Tori for generalized Benjamin-Ono equation
1 School of Mathematics and Statistics, Zhengzhou University, Zhengzhou, Henan, 450001, China
Received July 2014 Revised December 2014 Published March 2015
In this paper, we investigate one-dimensional generalized Benjamin-Ono equation, \begin{eqnarray} u_t+\mathcal{H}u_{xx}+u^{4}u_x=0,x\in\mathbb{T}, \end{eqnarray} and prove the existence of quasi-periodic solutions with two frequencies. The proof is based on partial Birkhoff normal form and an unbounded KAM theorem developed by Liu-Yuan[Commun.Math.Phys.307(2011)629-673].
Citation: Dongfeng Yan. KAM Tori for generalized Benjamin-Ono equation. Communications on Pure & Applied Analysis, 2015, 14 (3) : 941-957. doi: 10.3934/cpaa.2015.14.941
##### References:
[1] P. Baldi, Periodic solutions of fully nonlinear autonomous equations of Benjamin-Ono type,, \emph{Ann. Inst. H. Poincar Anal. Non Linaire}, 30 (2013), 33. doi: 10.1016/j.anihpc.2012.06.001. Google Scholar [2] P. Baldi, M. Berti and R. Montalto, KAM for quasi-linear and fully nonlinear forced perturbations of Airy equation,, \emph{Math. Ann.}, 359 (2014), 471. doi: 10.1007/s00208-013-1001-7. Google Scholar [3] P. Baldi, M. Berti and R. Montalto, KAM for quasi-linear KdV,, \emph{C. R. Math. Acad. Sci. Paris}, 352 (2014), 603. doi: 10.1016/j.crma.2014.04.012. Google Scholar [4] T. B. Benjamin, Internal waves of permanent form in fluids of great depth,, \emph{J. Fluid Mech.}, 29 (1967), 559. Google Scholar [5] M. Berti, L. Biasco and M. Procesi, KAM theory for the Hamiltonian derivative wave equations,, \emph{Arch. Ration. Mech. Anal.}, 212 (2014), 905. doi: 10.1007/s00205-014-0726-0. Google Scholar [6] J. Bourgain, Construction of quasi-periodic solutions for Hamiltonian perturbations of linear equations and application to nonlinear pde,, \emph{Int. Math. Res. Notices}, 11 (1994), 475. doi: 10.1155/S1073792894000516. Google Scholar [7] J. Bourgain, On Melnikov's persistence problem,, \emph{Math. Res. Lett.}, 4 (1997), 445. doi: 10.4310/MRL.1997.v4.n4.a1. Google Scholar [8] J. Bourgain, Quasi-periodic solutions of Hamiltonian perturbations for 2D linear Schrödinger equation,, \emph{Ann. Math.}, 148 (1998), 363. doi: 10.2307/121001. Google Scholar [9] J. Bourgain, Green's Function Estimates for Lattice Schrödinger Operators and Applications,, Annals of mathematics studies, (2005). Google Scholar [10] J. Bourgain, On invariant tori of full dimension for 1D periodic NLS,, \emph{J. Funct. Anal.}, 229 (2005), 62. doi: 10.1016/j.jfa.2004.10.019. Google Scholar [11] L. Chierchia and J. You, KAM tori for 1D nonlinear wave equation with periodic boundary conditions,, \emph{Commun. Math. Phys.}, 211 (2000), 497. doi: 10.1007/s002200050824. Google Scholar [12] G. Iooss, P. I. Plotnikov and J. F. Toland, Standing waves on an infinitely deep perfect fluid under gravity,, \emph{Arch. Ration. Mech. Anal.}, 177 (2005), 367. doi: 10.1007/s00205-005-0381-6. Google Scholar [13] J. R. Iorio, On the Cauchy problem for the Benjamin-Ono equation,, \emph{Comm. Partial Differential equations}, 11 (1986), 1031. doi: 10.1080/03605308608820456. Google Scholar [14] T. Kappler and J. Pöschel, KdV $&$ KAM,, Springer-Verlag, (2003). doi: 10.1007/978-3-662-08054-2. Google Scholar [15] C. E. Kenig, G. Ponce and L. Vega, On the generalized Benjamin-Ono equations,, \emph{Trans. Amer. Math. Soc.}, 342 (1994), 155. doi: 10.2307/2154688. Google Scholar [16] S. B. Kuksin, Hamiltonian perturbation of infinite-dimensional linear system with an imaginary spectrum,, \emph{Funkt. Anal. Prilozh.}, 21 (1987), 22. Google Scholar [17] S. B. Kuksin, Perturbation of quasiperiodic solutions of infinite-dimensional Hamiltonian systems,, \emph{Izv. Akad. Nauk SSSR, 52 (1989), 41. Google Scholar [18] S. B. Kuksin, Nearly Integrable Infinite-dimensional Hamiltonian Systems,, Springer-Verlag, (1993). Google Scholar [19] S. B. Kuksin and J. Pöschel, Invariant Cantor manifolds of quasi-periodic oscillations for a nonlinear Schrödinger equation,, \emph{Ann. of Math.}, 143 (1996), 149. doi: 10.2307/2118656. Google Scholar [20] S. B. Kuksin, On small denominators equations with large variable coefficients,, \emph{J. Appl. Math. Phys.}, 48 (1997), 262. doi: 10.1007/PL00001476. Google Scholar [21] S. B. Kuksin, A KAM theorem for equations of the Korteweg-de Vries type,, \emph{Rev. Math-Math Phys.}, 10 (1998), 1. Google Scholar [22] S. B. Kuksin, Analysis of Hamiltonian PDEs,, Oxford Univ. Press, (2000). Google Scholar [23] J. Liu and X. Yuan, Spectrum for quantum Duffing oscillator and small-divisor equation with large variable coefficient,, \emph{Commun. Pure Appl. Math.}, 63 (2010), 1145. doi: 10.1002/cpa.20314. Google Scholar [24] J. Liu and X. Yuan, A KAM theorem for Hamiltonian partial differential equations with unbounded perturbations,, \emph{Commun. Math. Phys.}, 307 (2011), 629. doi: 10.1007/s00220-011-1353-3. Google Scholar [25] J. Liu and X. Yuan, KAM for the derivative nonliear Schrödinger equation with periodic boundary conditions,, \emph{Journal of Differential Equations}, 256 (2014), 1627. doi: 10.1016/j.jde.2013.11.007. Google Scholar [26] L. Mi, Quasi-periodic solutions of derivative nonlinear Schrödinger equations with a given potential,, \emph{Journal of Mathematical Analysis and Applications}, 390 (2012), 335. doi: 10.1016/j.jmaa.2012.01.046. Google Scholar [27] L. Mi and K. Zhang, Invariant tori for Benjamin-Ono equation with unbounded quasi-periodically forced perturbation,, \emph{Discrete and Continuous Dynamical Systems-Series A}, 34 (2014), 689. doi: 10.3934/dcds.2014.34.689. Google Scholar [28] L. Molinet and F. Ribaud, Well-posedness results for the generalized Benjamin-Ono equation with small initial data,, \emph{J. Math. Pures Appl.}, 83 (2004), 277. doi: 10.1016/j.matpur.2003.11.005. Google Scholar [29] H. Ono, Algebraic solitary waves in stratified fluids,, \emph{Journal of the Physical Society of Japan}, 39 (1975), 1082. Google Scholar [30] J. Pöschel, A KAM theorem for some nonlinear PDEs,, \emph{Ann. Scuola Norm. Sup. Pisacl. Sci.}, 23 (1996), 119. Google Scholar [31] J. Pöschel, Quasi-periodic solutions for nonlinear wave equations,, \emph{Comm. Math. Helv.}, 71 (1996), 269. doi: 10.1007/BF02566420. Google Scholar [32] T. Tao, Global well-posedness of the Benjamin-Ono equation in H1(R),, \emph{J. Hyperbolic Differ. Equ.}, 1 (2004), 27. doi: 10.1142/S0219891604000032. Google Scholar [33] C. E. Wayne, Periodic and quasi-periodic solutions of nonlinear wave equation via KAM theory,, \emph{Commun. Math. Phys.}, 127 (1990), 479. Google Scholar [34] X. Yuan and K. Zhang, A reduction theorem for time dependent Schrödinger operator with finite differentiable unbounded perturbation,, \emph{J. Math. Phys.}, 54 (2013). doi: 10.1063/1.4803852. Google Scholar [35] J. Zhang, M. Gao and X. Yuan, KAM tori for reversible partial differential equations,, \emph{Nonlinearity}, 24 (2011), 1189. doi: 10.1088/0951-7715/24/4/010. Google Scholar
show all references
##### References:
[1] P. Baldi, Periodic solutions of fully nonlinear autonomous equations of Benjamin-Ono type,, \emph{Ann. Inst. H. Poincar Anal. Non Linaire}, 30 (2013), 33. doi: 10.1016/j.anihpc.2012.06.001. Google Scholar [2] P. Baldi, M. Berti and R. Montalto, KAM for quasi-linear and fully nonlinear forced perturbations of Airy equation,, \emph{Math. Ann.}, 359 (2014), 471. doi: 10.1007/s00208-013-1001-7. Google Scholar [3] P. Baldi, M. Berti and R. Montalto, KAM for quasi-linear KdV,, \emph{C. R. Math. Acad. Sci. Paris}, 352 (2014), 603. doi: 10.1016/j.crma.2014.04.012. Google Scholar [4] T. B. Benjamin, Internal waves of permanent form in fluids of great depth,, \emph{J. Fluid Mech.}, 29 (1967), 559. Google Scholar [5] M. Berti, L. Biasco and M. Procesi, KAM theory for the Hamiltonian derivative wave equations,, \emph{Arch. Ration. Mech. Anal.}, 212 (2014), 905. doi: 10.1007/s00205-014-0726-0. Google Scholar [6] J. Bourgain, Construction of quasi-periodic solutions for Hamiltonian perturbations of linear equations and application to nonlinear pde,, \emph{Int. Math. Res. Notices}, 11 (1994), 475. doi: 10.1155/S1073792894000516. Google Scholar [7] J. Bourgain, On Melnikov's persistence problem,, \emph{Math. Res. Lett.}, 4 (1997), 445. doi: 10.4310/MRL.1997.v4.n4.a1. Google Scholar [8] J. Bourgain, Quasi-periodic solutions of Hamiltonian perturbations for 2D linear Schrödinger equation,, \emph{Ann. Math.}, 148 (1998), 363. doi: 10.2307/121001. Google Scholar [9] J. Bourgain, Green's Function Estimates for Lattice Schrödinger Operators and Applications,, Annals of mathematics studies, (2005). Google Scholar [10] J. Bourgain, On invariant tori of full dimension for 1D periodic NLS,, \emph{J. Funct. Anal.}, 229 (2005), 62. doi: 10.1016/j.jfa.2004.10.019. Google Scholar [11] L. Chierchia and J. You, KAM tori for 1D nonlinear wave equation with periodic boundary conditions,, \emph{Commun. Math. Phys.}, 211 (2000), 497. doi: 10.1007/s002200050824. Google Scholar [12] G. Iooss, P. I. Plotnikov and J. F. Toland, Standing waves on an infinitely deep perfect fluid under gravity,, \emph{Arch. Ration. Mech. Anal.}, 177 (2005), 367. doi: 10.1007/s00205-005-0381-6. Google Scholar [13] J. R. Iorio, On the Cauchy problem for the Benjamin-Ono equation,, \emph{Comm. Partial Differential equations}, 11 (1986), 1031. doi: 10.1080/03605308608820456. Google Scholar [14] T. Kappler and J. Pöschel, KdV $&$ KAM,, Springer-Verlag, (2003). doi: 10.1007/978-3-662-08054-2. Google Scholar [15] C. E. Kenig, G. Ponce and L. Vega, On the generalized Benjamin-Ono equations,, \emph{Trans. Amer. Math. Soc.}, 342 (1994), 155. doi: 10.2307/2154688. Google Scholar [16] S. B. Kuksin, Hamiltonian perturbation of infinite-dimensional linear system with an imaginary spectrum,, \emph{Funkt. Anal. Prilozh.}, 21 (1987), 22. Google Scholar [17] S. B. Kuksin, Perturbation of quasiperiodic solutions of infinite-dimensional Hamiltonian systems,, \emph{Izv. Akad. Nauk SSSR, 52 (1989), 41. Google Scholar [18] S. B. Kuksin, Nearly Integrable Infinite-dimensional Hamiltonian Systems,, Springer-Verlag, (1993). Google Scholar [19] S. B. Kuksin and J. Pöschel, Invariant Cantor manifolds of quasi-periodic oscillations for a nonlinear Schrödinger equation,, \emph{Ann. of Math.}, 143 (1996), 149. doi: 10.2307/2118656. Google Scholar [20] S. B. Kuksin, On small denominators equations with large variable coefficients,, \emph{J. Appl. Math. Phys.}, 48 (1997), 262. doi: 10.1007/PL00001476. Google Scholar [21] S. B. Kuksin, A KAM theorem for equations of the Korteweg-de Vries type,, \emph{Rev. Math-Math Phys.}, 10 (1998), 1. Google Scholar [22] S. B. Kuksin, Analysis of Hamiltonian PDEs,, Oxford Univ. Press, (2000). Google Scholar [23] J. Liu and X. Yuan, Spectrum for quantum Duffing oscillator and small-divisor equation with large variable coefficient,, \emph{Commun. Pure Appl. Math.}, 63 (2010), 1145. doi: 10.1002/cpa.20314. Google Scholar [24] J. Liu and X. Yuan, A KAM theorem for Hamiltonian partial differential equations with unbounded perturbations,, \emph{Commun. Math. Phys.}, 307 (2011), 629. doi: 10.1007/s00220-011-1353-3. Google Scholar [25] J. Liu and X. Yuan, KAM for the derivative nonliear Schrödinger equation with periodic boundary conditions,, \emph{Journal of Differential Equations}, 256 (2014), 1627. doi: 10.1016/j.jde.2013.11.007. Google Scholar [26] L. Mi, Quasi-periodic solutions of derivative nonlinear Schrödinger equations with a given potential,, \emph{Journal of Mathematical Analysis and Applications}, 390 (2012), 335. doi: 10.1016/j.jmaa.2012.01.046. Google Scholar [27] L. Mi and K. Zhang, Invariant tori for Benjamin-Ono equation with unbounded quasi-periodically forced perturbation,, \emph{Discrete and Continuous Dynamical Systems-Series A}, 34 (2014), 689. doi: 10.3934/dcds.2014.34.689. Google Scholar [28] L. Molinet and F. Ribaud, Well-posedness results for the generalized Benjamin-Ono equation with small initial data,, \emph{J. Math. Pures Appl.}, 83 (2004), 277. doi: 10.1016/j.matpur.2003.11.005. Google Scholar [29] H. Ono, Algebraic solitary waves in stratified fluids,, \emph{Journal of the Physical Society of Japan}, 39 (1975), 1082. Google Scholar [30] J. Pöschel, A KAM theorem for some nonlinear PDEs,, \emph{Ann. Scuola Norm. Sup. Pisacl. Sci.}, 23 (1996), 119. Google Scholar [31] J. Pöschel, Quasi-periodic solutions for nonlinear wave equations,, \emph{Comm. Math. Helv.}, 71 (1996), 269. doi: 10.1007/BF02566420. Google Scholar [32] T. Tao, Global well-posedness of the Benjamin-Ono equation in H1(R),, \emph{J. Hyperbolic Differ. Equ.}, 1 (2004), 27. doi: 10.1142/S0219891604000032. Google Scholar [33] C. E. Wayne, Periodic and quasi-periodic solutions of nonlinear wave equation via KAM theory,, \emph{Commun. Math. Phys.}, 127 (1990), 479. Google Scholar [34] X. Yuan and K. Zhang, A reduction theorem for time dependent Schrödinger operator with finite differentiable unbounded perturbation,, \emph{J. Math. Phys.}, 54 (2013). doi: 10.1063/1.4803852. Google Scholar [35] J. Zhang, M. Gao and X. Yuan, KAM tori for reversible partial differential equations,, \emph{Nonlinearity}, 24 (2011), 1189. doi: 10.1088/0951-7715/24/4/010. Google Scholar
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2018 Impact Factor: 0.925
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https://www.makeageek.com/anecdotes-detail/enigma-and-cryptography/c51ce4d
|
Enigma
In 1918, German engineer Arthur Scherbius applied for a patent for a machine that coded and decoded secret messages quickly and easily. Scherbius’s Enigma shifted letters similarly to a Caesar cipher, but Enigma constantly changed the order in which the letters were shifted. Such pattern changes mask the nature of the cipher by appearing random. Without knowledge of the algorithms generating the cipher patterns, code breaking methods require enormous amounts of computation. With around $\fn_phv 10^{114}$ possible configurations, the Enigma seemed a cryptographically safe bet.
The Enigma worked quickly and accurately. While the Enigma had only modest commercial success, it became widely adopted by the German military. From the mid-$\fn_phv 1920s$ until the end of World War II, Germany and its allies encrypted and decrypted important communications using various versions of the Enigma.
Conquering Enigma
During World War II, many of the world’s best problem solvers considered cracking Enigma to be an insurmountable task. British mathematician Alan Turing viewed it as a challenge. Until the war, Turing lived in obscurity, working out the connections between logic and computing–work that laid the foundation for the design of modern computers. War provided Turing with a chance to prove the practical value of his work.
Using an understanding of cryptography, Turing went to work conquering Enigma. Polish experts who had built Enigma replicas furnished British intelligence with enough information to give Turing a much-needed starting point. But even armed with knowledge of Enigma’s design, Turing and other cryptographers required information about the way Enigma machines were configured. A few clues were needed to cut down on the enormity of the task of checking Enigma’s possible arrangements. British and Polish forces helped obtain those clues by capturing a few Enigma machines and in some cases observed the ways in which they were used.
Part of Turing’s brilliance was his ability to apply logic to machines. Turing designed an electromechanical device (based partially on a machine designed by Polish cryptographers) known as the bombe to help crack Enigma. With the number of possible configurations reduced, the bombe checked remaining possibilities until the right configuration was uncovered and Enigma’s messages deciphered.
The German military’s confidence in the invulnerability of Enigma played right into the hands of Allied intelligence. British cryptographers deciphered messages relating to German troop deployment and training in Russia and elsewhere. The information was so valuable that some historians speculate that conquering Enigma shortened the war in Europe by two years. For his wartime services, Turing was awarded the Order of the British Empire.
Turing is sometimes called the founder of modern computer science. Using an understanding of logic and practical engineering, Turing devised methods for data input and output, memory, and programming computers. His theoretical work brought him to the point of speculating that computers could be built that think for themselves. The themes of his work drive the study of artificial intelligence.
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http://umj-old.imath.kiev.ua/volumes/issues/?lang=en&year=2016&number=11
|
2019
Том 71
№ 11
# Volume 68, № 11, 2016
Article (Russian)
### Laplacian with respect to the measure on a Riemannian manifold and the Dirichlet problem. II
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1443-1449
We propose the $L^2$ -version of Laplacian with respect to measure on an (infinite-dimensional) Riemannian manifold. The Dirichlet problem for equations with proposed Laplacian is solved in a part of the Rimannian manifold of a certain class.
Article (Ukrainian)
### Almost periodic solutions of systems with delay and nonfixed times of impulsive action
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1450-1466
We study the existence and asymptotic stability of piecewise continuous almost periodic solutions for systems of differential equations with delay and nonfixed times of impulsive action that can be regarded as mathematical models of neural networks.
Article (Ukrainian)
### Estimations of the Laplace – Stieltjes integrals
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1467-1482
We study the Laplace – Stieltjes integrals with an arbitrary abscissa of convergence. The lower and upper estimates for these integrals are established. The accumulated results are used to deduce the relationships between the growth of the integral and the maximum of the integrand.
Article (English)
### General proximal point algorithm for monotone operators
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1483-1492
We introduce a new general proximal point algorithm for an infinite family of monotone operators in a real Hilbert space. We establish strong convergence of the iterative process to a common zero point of the infinite family of monotone operators. Our result generalizes and improves numerous results in the available literature.
Article (Ukrainian)
### I. Approximative properties of biharmonic Poisson integrals in the classes $W^r_{\beta} H^{\alpha}$
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1493-1504
We deduce asymptotic equalities for the least upper bounds of approximations of functions from the classes $W^r_{\beta} H^{\alpha}$, and $H^{\alpha}$ by biharmonic Poisson integrals in the uniform metric.
Article (Ukrainian)
### Asymptotically independent estimators in a structural linear model with measurement errors
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1505-1517
We consider a structural linear regression model with measurement errors. A new parameterization is proposed, in which the expectation of the response variable plays the role of a new parameter instead of the intercept. This enables us to form three groups of asymptotically independent estimators in the case where the ratio of variances of the errors is known and two groups of this kind if the variance of the measurement error in the covariate is known. In this case, it is not assumed that the errors and the latent variable are normally distributed.
Article (Ukrainian)
### Sufficient conditions under which the solutions of general parabolic initial-boundaryvalue problems are classical
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1518-1527
We establish new sufficient conditions under which the generalized solutions of initial-boundary-value problems for the linear parabolic differential equations of any order with complex-valued coefficients are classical. These conditions are formulated in the terms of belonging of the right-hand sides of this problem to certain anisotropic H¨ormander spaces. In the definition of classical solution, its continuity on the line connecting the lateral surface with the base of the cylinder (in which the problem is considered) is not required.
Article (Ukrainian)
### Two-dimensional Coulomb dynamics of two and three equal negative charges in the field of two equal fixed positive charges
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1528-1539
Periodic and bounded for positive time solutions of the planar Coulomb equation of motion for two and three identical negative charges in the field of two equal fixed positive charges are found. The systems possess equilibrium configurations to which the found bounded solutions converge in the infinite time limit. The periodic solutions are obtained with the help of the Lyapunov center theorem.
Article (English)
### Hypersurfaces with nonzero constant Gauss – Kronecker curvature in $M^{n+1}(±1)$
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1540-1551
We study hypersurfaces in a unit sphere and in a hyperbolic space with nonzero constant Gauss – Kronecker curvature and two distinct principal curvatures one of which is simple. Denoting by $K$ the nonzero constant Gauss – Kronecker curvature of hypersurfaces, we obtain some characterizations of the Riemannian products $S^{n-1}(a) \times S^1(\sqrt{1 - a^2}),\quad$ $a^2 = 1/\left(1 + K^{\frac{2}{n - 2}}\right)$ or $S^{n-1}(a) \times H^1(- \sqrt{1 + a^2}),\quad$ $a^2 = 1/\left(K^{\frac{2}{n - 2}} - 1\right)$.
Article (English)
### A construction of regular semigroups with quasiideal regular *-transversals
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1552-1560
Let $S$ be a semigroup and let “$\ast$ ” be a unary operation on S satisfying the following identities: $$xx^{\ast} x = x, x^{\ast} xx^{\ast} = x^{\ast},\; x^{\ast \ast \ast} = x^{\ast},\; (xy^{\ast} )^{\ast} = y^{\ast \ast} x^{\ast},\; (x^{\ast} y)^{\ast} = y^{\ast} x^{\ast \ast}.$$ Then S\ast = \{ x\ast | x \in S\} is called a regular \ast -transversal of $S$ in the literatures. We propose a method for the construction of regular semigroups with quasiideal regular $\ast$ -transversals based on the use of fundamental regular semigroups and regular $\ast$ -semigroups.
Article (English)
### On the growth of meromorphic solutions of difference equation
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1561-1570
We estimate the order of growth of meromorphic solutions of some linear difference equations and study the relationship between the exponent of convergence of zeros and the order of growth of the entire solutions of linear difference equations.
Brief Communications (Ukrainian)
### Complete classification of finite semigroups for which the inverse monoid of local automorphisms is a permutable semigroup
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1571-1578
A semigroup $S$ is called permutable if $\rho \circ \sigma = \sigma \circ \rho$. for any pair of congruences $\rho, \sigma$ on $S$. A local automorphism of semigroup $S$ is defined as an isomorphism between two of its subsemigroups. The set of all local automorphisms of the semigroup $S$ with respect to an ordinary operation of composition of binary relations forms an inverse monoid of local automorphisms. We present a complete classification of finite semigroups for which the inverse monoid of local automorphisms is permutable.
Brief Communications (Ukrainian)
### On the equivalence of some perturbations of the operator of multiplication by the independent variable
Ukr. Mat. Zh. - 2016. - 68, № 11. - pp. 1579-1584
We study the conditions of equivalence of two operators obtained as perturbations of the operator of multiplication by the independent variable by certain Volterra operators in the space of functions analytic in an arbitrary domain of the complex plane starlike with respect to the origin.
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https://shreddercenter.blog/2018/04/28/fourier-fun/
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# Fourier Fun
[latexpage]
::
### Fourier Series
Allows us to expand any periodic funciton on the range $(-L,L)$ in terms of sinusoidal functions that are periodic on that interval
$f(x)=\sum _{ n=0 }^{ \infty }{ A_{ n }\cos (\frac { n\pi /*x }{ L } ) } +\sum _{ n=0 }^{ \infty }{ B_{ n }\sin (\frac { n\pi x }{ L } ) }$
• Recall Euler’s formula: $e^z = e^{s+it} = e^s e^{it} = e^{s}(\cos(t)+i\sin(t))$
• Euler’s identity gives $e^{i\pi} + 1 = 0$ (i.e., $e^{i/pi}=-1$)
• This is a consequence of Euler’s formula:
• $e^{ix} = \cos x + i \sin x$ ⇒ let $x = \pi$ $e^{i\pi} = \cos(\pi) + i\sin(\pi) = -1 + i(0) = -1$
• Since the sines and cosines can be combined into a complex exponential, we can use this equivalency to simplify $f(x)$ into a single term:
$f(x) = \sum_{n=-\infty}^{\infty}{a_n e^{in\pi x/L}}$
where $a_n=\frac{1}{2L} \int _{ -L}^{L}{f(x)e^{-in\pi x/L}dx}$
### Review of sine and cosine:
#### Cosine Function
• Even function ⇒ $\cos(-x) = cos(x)$ ⇒ symmetric
• $\int _{-\pi}^{\pi}{\cos(\theta)d\theta} = 0$
#### Sine Function
• Odd function ⇒ $\sin(-x) = -\sin(x)$ 1 ⇒ antisymmetric
• $\int _{-\pi}^{\pi}{\sin(\theta)d\theta} = 0$
### The Fourier Transform
Note: a majority of these equations I got from the first reference I listed
Let $g(t)$ be a function of time and $G(\omega)$ be a function of frequency
• Aside: $\omega \equiv 2\pi \upsilon$ where $\omega =$ angular frequency and $\upsilon =$ oscillation frequency
• Then, the FT of $g(t)$ (if it exists) is …
$G(\omega) = \mathcal{F} \{g(t) \} = \sqrt { \frac { |b| }{ (2\pi )^{ 1-a } } } \int _{ -\infty }^{ \infty }{g(t)e^{ib\omega t}dt}$
$g(t) = \mathcal{F}^{-1} \{g(t) \} = \mathcal{F} \{G(\omega ) \} = \sqrt { \frac { |b| }{ (2\pi )^{ 1+a } } } \int _{ -\infty }^{ \infty }{G(\omega)e^{-ib\omega t}d\omega}$
#### Some common parameter choices
• Physics and Mathematica default: $a = 0, b =1$
$G(\omega) = \sqrt { \frac { |1| }{ (2\pi )^{ 1-0 } } } \int _{ -\infty }^{ \infty }{g(t)e^{i(1)\omega t}dt} = \sqrt { \frac { 1 }{ (2\pi ) } } \int _{ -\infty }^{ \infty }{g(t)e^{i\omega t}dt}$
$G(\omega) = \sqrt { \frac { 1 }{ (2\pi ) } } \int _{ -\infty }^{ \infty }{g(t)e^{i\omega t}dt}$
• Pure mathematics and systems engineering: $a=1, b =-1$
$G(\omega) = \sqrt { \frac { |-1| }{ (2\pi )^{ 1-1 } } } \int _{ -\infty }^{ \infty }{g(t)e^{i(-1)\omega t}dt} = \sqrt { \frac { 1 }{ (2\pi )^0 } } \int _{ -\infty }^{ \infty }{g(t)e^{-i\omega t}dt} = \int _{ -\infty }^{ \infty }{g(t)e^{-i\omega t}dt}$
$G(\omega) = \int _{ -\infty }^{ \infty }{g(t)e^{-i\omega t}dt}$
• Classical physics: $a=-1, b=1$
$G(\omega) = \sqrt { \frac { |1| }{ (2\pi )^{ 1-(-1) } } } \int _{ -\infty }^{ \infty }{g(t)e^{i(1)\omega t}dt} = \sqrt { \frac { 1 }{ (2\pi )^2 } } \int _{ -\infty }^{ \infty }{g(t)e^{i\omega t}dt} = \frac{1}{2\pi }\int _{ -\infty }^{ \infty }{g(t)e^{-i\omega t}dt}$
$G(\omega) = \frac{1}{2\pi }\int _{ -\infty }^{ \infty }{g(t)e^{-i\omega t}dt}$
• Signal processing: $a = 0, b = -2\pi$
$G(\omega) = \sqrt { \frac { |-2\pi| }{ (2\pi )^{ 1-(0) } } } \int _{ -\infty }^{ \infty }{g(t)e^{i(-2\pi)\omega t}dt} = sqrt { \frac { 2\pi }{ 2\pi} } \int _{ -\infty }^{ \infty }{g(t)e^{-i2\pi \omega t}dt} = \int _{ -\infty }^{ \infty }{g(t)e^{-i2\pi \omega t}dt}$
$G(\omega) = \int _{ -\infty }^{ \infty }{g(t)e^{-i2\pi \omega t}dt}$
### Fourier Transform in Quantum Mechanics
Note: most of this material comes from the second link listed under my sources.
#### Conjugate pairs
• A conjugate pair is a pair of variables that are related to one another via the FT.
• Two conjugate pairs that exist in nature are:
1. Time ($t$) and frequency ($\upsilon$):
• $G(\upsilon) = \mathcal{F} \{ g(t) \} = \frac{1}{\sqrt{2\pi}} \int_{-\infty}^{\infty}{e^{-i\upsilon t}g(t)dt}$
• $g(t) = \mathcal{F} \{ G(\upsilon) \} = \mathcal{F}^{-1} \{ g(t) \} = \frac{1}{\sqrt{2\pi}} \int_{-\infty}^{\infty}{e^{i\upsilon t}G(\upsilon) d\upsilon }$
2. Position ($x$) and momentum ($\rho$):
• $\phi(\rho) = \mathcal{F} \{ \Psi(x) \} = \frac{1}{\sqrt{2\pi \hbar}} \int_{-\infty}^{\infty}{e^{-i\rho x/ \hbar} \Psi (x)dx}$
• $\Psi(x) = \mathcal{F} \{ \phi (\rho) \} = \mathcal{F}^{-1} \{ \Phi(x) \} = \frac{1}{\sqrt{2\pi \hbar}} \int_{-\infty}^{\infty}{e^{i\rho x/ \hbar} \phi (\rho) d\rho}$
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http://mathhelpforum.com/calculus/36558-definitely-integral.html
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# Math Help - Definitely Integral
1. ## Definitely Integral
To all Integral lovers,
In the Spirit of Integration....here is a popular integral
$\int\limits_0^{\frac {\pi }{4}} {\ln \left( {1 + \tan x} \right)dx}$
Well Enjoy,
Isomorphism
P.S: Elegant methods score can score a lot of 'thank you's
2. Originally Posted by ThePerfectHacker
I will wait for some different way of doing it. I have a solution that looks more elegant... but it is almost the same as you did....
3. OK i will post my solution since nobody else replied
$I = \int\limits_0^{\frac {\pi }{4}} {\ln \left( {1 + \tan x} \right)dx}$
$I = \int\limits_0^{\frac {\pi }{4}} {\ln \left( {1 + \tan \left(\frac{\pi}4 - x\right)} \right)dx}$
$I =\int\limits_0^{\frac {\pi }{4}} \ln \frac2{1 + \tan x} dx$
$I = \int\limits_0^{\frac {\pi }{4}}\ln 2 \,dx - I$
So $I = \frac{\pi}8 \ln2$
Part 2:
$\int^1_0\frac{x^4(1-x)^4}{1+x^2} dx$
This is a funny integral... not hard... but the answer is interesting
People who solve it can comment on the answer rather than showing the answer
4. Originally Posted by Isomorphism
OK i will post my solution since nobody else replied
$I = \int\limits_0^{\frac {\pi }{4}} {\ln \left( {1 + \tan x} \right)dx}$
$I = \int\limits_0^{\frac {\pi }{4}} {\ln \left( {1 + \tan \left(\frac{\pi}4 - x\right)} \right)dx}$
$I =\int\limits_0^{\frac {\pi }{4}} \ln \frac2{1 + \tan x} dx$
$I = \int\limits_0^{\frac {\pi }{4}}\ln 2 \,dx - I$
So $I = \frac{\pi}8 \ln2$
Part 2:
$\int^1_0\frac{x^4(1-x)^4}{1+x^2} dx$
This is a funny integral... not hard... but the answer is interesting
People who solve it can comment on the answer rather than showing the answer
Haha...but how close is that approximation to the real thing...is it less or more making this positive or negative haha
5. Originally Posted by Mathstud28
Haha...but how close is that approximation to the real thing...is it less or more making this positive or negative haha
Hmm actually this is used to approximate 'it' by the use of sandwiching the integral between two series :P
6. I thought of converting this thread into an "integral collection of my life". So I will be posting integrals here that seem nice to me. Anyone who thinks (s)he has a nice solution, can of course post them here... Thank you
The next one in the set:
Part 3:
$\int_0^\infty \frac{dx}{1+x^4}$
7. Originally Posted by Isomorphism
Part 3:
$\int_0^\infty \frac{dx}{1+x^4}$
If I remember correctly: $\int_0^{\infty} \frac{dx}{x^n+1} = \frac{(\pi/n)}{\sin (\pi/n)}$ where $n\geq 2$.
8. Originally Posted by ThePerfectHacker
If I remember correctly: $\int_0^{\infty} \frac{dx}{x^n+1} = \frac{(\pi/n)}{\sin (\pi/n)}$ where $n\geq 2$.
Can you prove that without complex analysis(that is without using residues)?
9. Originally Posted by Isomorphism
Can you prove that without complex analysis(that is without using residues)?
Do you mean by decomposition on the bottom or do you mean by using something else?
10. $\int_0^\infty \frac{dx}{1+x^4}$ can be solved without complex numbers. I used only pure substitution and algebraic tricks
P.S: Unfortunately what I did only holds for this problem . It does not work for TPH's generalization.
11. Originally Posted by Isomorphism
Can you prove that without complex analysis(that is without using residues)?
Combine Gamma & Beta functions plus the Euler Reflection Formula.
12. Originally Posted by Krizalid
Combine Gamma & Beta functions plus the Euler Reflection Formula.
huh?
13. Let $\int_{0}^{\infty }{\frac{1}{1+x^{n}}\,dx}.$ Make the substitution $z=x^n,$ hence
\begin{aligned}
\int_{0}^{\infty }{\frac{1}{1+x^{n}}\,dx}&=\frac{1}{n}\int_{0}^{\in fty }{\frac{z^{1/n-1}}{1+z}\,dz}\\
&=\frac{1}{n}\beta \left(\frac{1}{n},1-\frac{1}{n}\right)\\
&=\frac{1}{n}\cdot \frac{\Gamma \left( n^{-1}\right)\Gamma\left( 1-n^{-1} \right)}{\Gamma (1)}\\
\end{aligned}
Note aside: I've heard that the Reflection Formula can be only proved via complex analysis. It's a dream to see a solution with elementary tools.
14. Here is the latest update of "Definitely Integral"
Compute I:
$\boxed{I = \int_0^{\pi/4}\ln(\sin x) \cdot \ln(\cos x)\,dx}$
P.S:I think its quite hard
Page 1 of 2 12 Last
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https://socratic.org/questions/how-do-you-solve-for-g-in-t-2pisqrt-l-g
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Physics
Topics
# How do you solve for g in T=2pisqrt(L/g)?
Aug 10, 2016
$g = \frac{4 {\pi}^{2} L}{T} ^ 2$
#### Explanation:
$\textcolor{red}{\text{First,}}$ what you want to do is square both sides of the equation to get rid of the square root, since squaring a number is the inverse of taking the square root of a number:
${T}^{2} = {\left(2 \pi\right)}^{2} \sqrt{{\left(\frac{L}{g}\right)}^{2}}$
${T}^{2} = {\left(2 \pi\right)}^{2} \left(\frac{L}{g}\right)$
$\textcolor{b l u e}{\text{Second,}}$ we simplify the ${\left(2 \pi\right)}^{2}$ part so it's easier to read. Remember, when you square something in parenthesis, you are squaring every single term inside:
${T}^{2} = 4 {\pi}^{2} \left(\frac{L}{g}\right)$
$\textcolor{p u r p \le}{\text{third,}}$ multiply both sides by $g$:
$g \times {T}^{2} = 4 {\pi}^{2} \left(\frac{L}{\cancel{\text{g}}}\right) \times \cancel{g}$
$g \times {T}^{2} = 4 {\pi}^{2} L$
$\textcolor{m a r \infty n}{\text{finally,}}$ divide both sides by ${T}^{2}$ to get $g$ by itself:
$\frac{g \times {\cancel{T}}^{2}}{\cancel{T}} ^ 2 = \frac{4 {\pi}^{2} L}{T} ^ 2$
Thus, $g$ is equal to:
$g = \frac{4 {\pi}^{2} L}{T} ^ 2$
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https://db0nus869y26v.cloudfront.net/en/South_African_rand
|
South African rand
List
• 10 other official names:
• Suid-Afrikaanse rand
• iRanti yeSewula Afrika
• iRanti yoMzantsi Afrika (Xhosa)
• iRandi laseNingizimu Afrika (Zulu)
• liRandi laseNingizimu Afrika (Swazi)
• Ranta ya Afrika-Borwa
• Ranta ya Afrika Borwa (Sotho)
• Ranta ya Aforika Borwa (Tswana)
• Rhandi ya Afrika-Dzonga (Tsonga)
• Rannda ya Afurika Tshipembe (Venda)
ISO 4217
CodeZAR
Number710
Exponent2
Unit
Pluralrand
SymbolR
Denominations
Subunit
1100Cent
Symbol
c
BanknotesR 10, R 20, R 50, R 100, R 200
Coins10c, 20c, 50c, R 1, R 2, R 5, Krugerrand
Demographics
Official user(s)[a]
[b]
[c]
Eswatini[d]
Unofficial user(s)
[e]
Issuance
Central bankSouth African Reserve Bank
Websitewww.resbank.co.za
PrinterSouth African Bank Note Company
MintSouth African Mint
Websitewww.samint.co.za
Valuation
Inflation4.1% (South Africa only)
SourceSouth African Reserve Bank, March 2020
MethodCPI
Pegged by Namibian dollar
Lesotho loti
Swazi lilangeni
(at par)
1. ^ A Common Monetary Area member.
2. ^ A Common Monetary Area member, used alongside Namibian dollar
3. ^ A Common Monetary Area member, used alongside Lesotho loti
4. ^ A Common Monetary Area member, used alongside Swazi lilangeni
5. ^ Alongside Zimbabwean dollar (suspended indefinitely from 12 April 2009), euro, US dollar, pound sterling, Botswana pula, Indian rupee, Australian dollar, Chinese yuan, and Japanese yen. The US dollar has been adopted as the official currency for all government transactions.
The South African rand, or simply the rand, (sign: R; code: ZAR[a]) is the official currency of the Southern African Common Monetary Area: South Africa, Namibia (alongside the Namibian dollar), Lesotho (alongside the Lesotho loti) and Eswatini (alongside the Swazi lilangeni). It is subdivided into 100 cents (sign: "c").
The South African rand is legal tender in the Common Monetary Area member states of Namibia, Lesotho and Eswatini, with these three countries also having their own national currency (the dollar, the loti and the lilangeni respectively) pegged with the rand at parity and still widely accepted as substitutes. The rand was also legal tender in Botswana until 1976, when the pula replaced the rand at par.
## Etymology
The rand takes its name from the Witwatersrand ("white waters' ridge" in English, rand being the Dutch and Afrikaans word for 'ridge'), the ridge upon which Johannesburg is built and where most of South Africa's gold deposits were found.
## History
The rand was introduced in the Union of South Africa in 1961, three months before the country declared itself a republic.[1] A Decimal Coinage Commission had been set up in 1956 to consider a move away from the denominations of pounds, shillings, and pence; it submitted its recommendations on 8 August 1958.[2] It replaced the South African pound as legal tender, at the rate of 2 rand to 1 pound, or 10 shillings to the rand. The government introduced a mascot, Decimal Dan, "the rand-cent man" (known in Afrikaans as Daan Desimaal).[3] This was accompanied by a radio jingle, to inform the public about the new currency.[4] Although pronounced in the Afrikaans style as /rʌnt/ in the jingles when introduced,[5] the contemporary pronunciation in South African English is /rænd/.[6]
### Brief exchange rate history
#### 1961–2000
Value of the South African rand to the United States dollar from 1975 to 2015 by the blue columns: The percentage rate of change year-on-year is shown by the black line.[7]
One rand was worth US\$1.40 (R 0.72 per dollar) from the time of its inception in 1961 until late 1971, and the U.S. dollar became stronger than South African currency for the first time on 15 March 1982.[8] Its value thereafter fluctuated as various exchange rate dispensations[clarification needed] were implemented by the South African authorities. By the early 1980s, high inflation and mounting political pressure combined with sanctions placed against the country due to international opposition to the apartheid system had started to erode its value. The currency broke above parity with the dollar for the first time in March 1982, and continued to trade between R 1 and R 1.30 to the dollar until June 1984, when depreciation of the currency gained momentum. By February 1985, it was trading at over R 2 per dollar, and in July that year, all foreign exchange trading was suspended for three days to try to stop the depreciation.
By the time that State President P. W. Botha made his Rubicon speech on 15 August 1985, it had weakened to R 2.40 per dollar. The currency recovered somewhat between 1986 and 1988, trading near the R 2 level most of the time and even breaking beneath it sporadically. The recovery was short-lived, however, and by the end of 1989, the rand was trading at more than R 2.50 per dollar.
As it became clear in the early 1990s that the country was destined for Black majority rule and one reform after the other was announced, uncertainty about the future of the country hastened the depreciation until the level of R 3 to the dollar was breached in November 1992. A host of local and international events influenced the currency after that, most notably the 1994 general election, which had it weaken to over R 3.60 to the dollar, the election of Tito Mboweni as the governor of the South African Reserve Bank, and the inauguration of President Thabo Mbeki in 1999, which had it quickly slide to over R 6 to the dollar. The controversial land reform programme that was initiated in Zimbabwe, followed by the September 11, 2001 attacks, propelled it to its weakest historical level of R 13.84 to the dollar in December 2001.
#### 2001–2011
Two generations of older notes and coins: The notes of the latter of these two generations (as depicted by the R 5 note in this image) were replaced with the iconic "Big Five" notes and these were recently updated to show the face of Nelson Mandela.
Banknotes and coins of the South African rand's fourth series (2005–2012). Set of ZAR notes 2012 to present tax collection ZAR:6,100,000,000,000
This sudden depreciation in 2001 led to a formal investigation, which in turn led to a dramatic recovery. By the end of 2002, the currency was trading under R 9 to the dollar again, and by the end of 2004 was trading under R 5.70 to the dollar. The currency softened somewhat in 2005, and was trading around R 6.35 to the dollar at the end of the year. At the start of 2006, however, the currency resumed its rally, and as of 19 January 2006, was trading under R 6 to the dollar again. However, during the second and third quarters of 2006 (i.e. April through September), the rand weakened significantly.
In sterling terms, it fell from around 9.5% to just over 7%, losing some 25% of its international trade-weighted value in just six months. In late 2007, the rand rallied modestly to just over 8%, only to experience a precipitous slide during the first quarter of 2008.
This downward slide could be attributed to a range of factors: South Africa's worsening current account deficit, which widened to a 36‑year high of 7.3% of gross domestic product (GDP) in 2007; inflation at a five-year high of just under 9%; escalating global risk aversion as investors' concerns over the spreading impact of the sub-prime crisis grew; and a general flight to "safe havens", away from the perceived risks of emerging markets. The rand depreciation was exacerbated by the Eskom electricity crisis, which arose from the utility being unable to meet the country's rapidly growing energy demands.
#### 2012–present
A stalled mining industry in late 2012 led to new lows in early 2013.[9] In late January 2014, the rand slid to R 11.25 to the dollar, with analysts attributing the shift to "word from the US Federal Reserve that it would trim back stimulus spending, which led to a massive sell-off in emerging economies."[10] In 2014, South Africa experienced its worst year against the US dollar since 2009,[11] and in March 2015, the rand traded at its worst since 2002.[11] At the time, Trading Economics released data that the rand "averaged R4.97 to the dollar between 1972–2015, reaching an all time high of R12.45 in December 2001 and a record low of R0.67 in June of 1973."[11] By the end of 2014, the rand had weakened to R 15.05 per dollar, partly due to South Africa's consistent trade account deficit with the rest of the world.
From 9–13 December 2015, over a four-day period, the rand dropped over 10% due to what some suspected was President Zuma's surprise announcement that he would be replacing the Finance Minister Nhlanhla Nene with the little-known David van Rooyen. The rapid drop in value was stemmed when Zuma backtracked and announced that the better-known previous Minister of Finance, Pravin Gordhan, would instead be appointed to the post. Zuma's surprise sacking of Nene damaged international confidence in the rand, and the exchange rate was volatile throughout much of January 2016, and reached an all-time low of R 17.9169 to the US dollar on 9 January 2016 before rebounding to R 16.57 later the same day.[12]
The January drop in value was also partly caused by Japanese retail investors cutting their losses in the currency to look for higher-yield investments elsewhere and due to concerns over the impact of the economic slowdown in China, South Africa's largest export market.[13] By mid-January, economists were speculating that the rand could expect to see further volatility for the rest of 2016.[14][15] By 29 April, it reached its highest performance over the previous five months, exchanging at a rate of 14.16 to the United States dollar.[16]
Following the United Kingdom voting to leave the European Union, the rand dropped in value over 8% against the US\$ on 24 June 2016, the currency's largest single-day decline since the 2008 economic crash.[17] This was partly due to a general global financial retreat from currencies seen as risky to the US dollar[18] and partly due to concerns over how British withdrawal from the EU would impact the South African economy and trade relations.[17][19]
In April 2017, a Reuters poll estimated that the rand would remain relatively stable for the rest of the year, as two polls found that analysts had already factored in a possible downgrade to "junk" status. At the time, Moody's rated South Africa two notches above junk status.[20] When President Jacob Zuma narrowly won a motion of no confidence in South Africa in August 2017, the rand continued to slide, dropping 1.7% that day.[21] In September 2017, Goldman Sachs said that the debt and corruption of Eskom Holdings was the biggest risk to South Africa's economy and the exchange rate of the rand. At the time, it had no permanent CEO, and Colin Coleman of Goldman Sachs in Africa said the company was "having discussions on solutions" on finding credible management.[22] In October 2017, the rand firmed against the US dollar as it recovered from a six-month low. Reuters noted that "South Africa is highly susceptible to global investor sentiment as the country relies on foreign money to cover its large budget and current account deficits."[23] On 13 November 2017, the rand fell by over 1% when the budget chief Michael Sachs stood down from his position in Zuma's administration.[24]
## Coins
Main article: Coins of the South African rand
A 5-rand bimetallic coin issued in 2004
Coins were introduced in 1961 in denominations of 12, 1, 2+12, 5, 10, 20, and 50 cents. In 1965, 2-cent coins replaced the 2+12-cent coins. The 12-cent coin was last struck for circulation in 1973. The 1-rand coin for circulation was introduced in 1967, followed by 2-rand coins in 1989 and 5-rand coins in 1994. Production of the 1- and 2-cent coins was discontinued in 2002, followed by 5-cent coins in 2012, primarily due to inflation having devalued them, but they remain legal tender.[25][26][27][28] Shops normally round the total purchase price of goods to the nearest 10 cents (in favour of the consumer).
In an effort to curb counterfeiting, a new 5-rand coin was released in August 2004. Security features introduced on the coin include a bimetal design (similar to the €1 and €2 coins, the Thai ฿10 coin, the Philippine ₱10 coin [the coin was changed the composition to nickel-plated steel in 2018], the British £2 coin, and the Canadian \$2 coin), a specially serrated security groove along the rim and microlettering.[29]
## Banknotes
The first series of rand banknotes was introduced in 1961 in denominations of 1-, 2-, 10-, and 20-rand, with similar designs and colours to the preceding pound notes to ease the transition. They bore the image of what was believed at the time to be Jan van Riebeeck, the first V.O.C. administrator of Cape Town. It was later discovered that the image was not in fact Van Riebeeck at all, a portrait of Bartholomeus Vermuyden had been mistaken for Van Riebeeck.[30] Like the last pound notes, they were printed in two variants, one with English written first and the other with Afrikaans written first.[citation needed]
In 1966, a second series was released with designs which moved away from the previous pound notes. Notes with denominations of 1-, 5- and 10-rand were produced with predominantly one colour per note. A smaller 1-rand note with the same design was introduced in 1973 and a 2-rand note was introduced in 1974. The 20-rand denomination from the first series was dropped. All notes bore the image of Jan van Riebeeck. The practice of having an English and an Afrikaans version of each note was continued in this series.[citation needed]
The 1978 series began with denominations of 2-, 5-, 10- and 20-rand, with a 50-rand introduced in 1984. This series had only one language variant for each denomination of note. Afrikaans was the first language on the 2-, 10-, and 50-rand, while English was the first language on the 5- and 20-rand. The 1-rand note was replaced by a coin.
South African ATM showing R 50 and R 100 banknotes.
In the 1990s, the notes were redesigned with images of the Big Five wildlife species. 10-, 20- and 50-rand notes were introduced in 1992 & 1993, retaining the colour scheme of the previous issue. Coins were introduced for the 2- and 5-rand, replacing the notes of the previous series, mainly because of the severe wear and tear experienced with low-denomination notes in circulation. In 1994, 100- and 200-rand notes were introduced.[citation needed]
The 2005 series has the same principal design, but with additional security features such as colour-shifting ink on the 50-rand and higher and the EURion constellation. The obverses of all denominations were printed in English, while two other official languages were printed on the reverse, thus making use of all 11 official languages of South Africa.
In 2010, the South African Reserve Bank and commercial banks withdrew all 1994 series 200-rand banknotes due to relatively high-quality counterfeit notes in circulation.[31]
In 2011, the South African Reserve Bank issued 100-rand banknotes which were defective because they lacked fluorescent printing visible under UV light. In June, printing of this denomination was moved from the South African Bank Note Company to Crane Currency's Swedish division (Tumba Bruk), which reportedly produced 80 million 100-rand notes.[32] The South African Reserve Bank shredded 3.6 million 100-rand banknotes printed by Crane Currency because they had the same serial numbers as a batch printed by the South African Bank Note Company. In addition, the notes printed in Sweden were not the correct colour, and they were 1 mm short.[33]
On 11 February 2012, President Jacob Zuma announced that the country would be issuing a new set of banknotes bearing Nelson Mandela's image.[34][35] They were entered into circulation on 6 November 2012.[36] These contained the same denominations of 10-, 20-, 50-, 100-, and 200-rand.
In 2013, the 2012 series was updated with the addition of the EURion constellation to all five denominations.[37]
On 18 July 2018, a special commemorative series of banknotes was released in commemoration of the 100th anniversary of Nelson Mandela's birth. This series includes notes of all denominations, 10-, 20-, 50-, 100-, and 200-rand. These notes will circulate alongside the existing notes.[38] The notes depict the standard face of Nelson Mandela on the obverse, but instead of the Big Five animals on the reverse, they show a younger Mandela with different iconic scenes relating to his legacy. These scenes comprise: the rolling hills of the Eastern Cape, featuring Mandela's humble birthplace of Mvezo (10-rand); the home of Mandela in Soweto, where he defined his political life alongside other struggle icons (20-rand); the site where Mandela was captured near Howick, following 17 months in hiding, where a monument to him has been erected (50-rand); the place of Mandela's 27-year imprisonment at Robben Island, showing a pile of quarried limestone (100-rand); the statue of Mandela at the Union Buildings in remembrance of when he was inaugurated there in 1994 (200-rand).[39][40][41]
### First series
Banknotes of the South African rand (1961 First Issue)[42]
Image Value Obverse Reverse Colour Language Size (mm)
[43] 1 rand Jan van Riebeeck Lion from coat of arms Brown Afrikaans/English, English/Afrikaans 136×78
[44] 2 rand Lion from coat of arms Blue Afrikaans/English, English/Afrikaans 149×84
[45] 10 rand Jan van Riebeeck's sailing ship Green Afrikaans/English, English/Afrikaans 170×96
[46] 20 rand Gold mine Purple Afrikaans/English, English/Afrikaans 176×103
### Second series
Banknotes of the South African rand (1966 Second Issue)[42]
Image Value Obverse Reverse Colour Language Size (mm)
[47] 1 rand Jan van Riebeeck and protea Farming and agriculture Brown Afrikaans/English, English/Afrikaans 128×64
1 rand Jan van Riebeeck and protea Farming and agriculture Brown Afrikaans/English, English/Afrikaans 120×57
2 rand Jan van Riebeeck, Cape Dutch architecture and vines Gariep Dam, pylon and maize cob Blue Afrikaans/English, English/Afrikaans 127×63
[48] 5 rand Jan van Riebeeck, Voortrekker Monument and Great Trek Mining Purple Afrikaans/English, English/Afrikaans 134×70
[49] 10 rand Jan van Riebeeck, Union Buildings and springbok Jan van Riebeeck's three ships Green Afrikaans/English, English/Afrikaans 140×76
### Third series
Banknotes of the South African rand (1978 Third Issue)[42]
Image Value Obverse Reverse Colour Language Size (mm)
[50] 2 rand Jan van Riebeeck and pylon Sasol coal to oil refinery Blue Afrikaans and English 120×57
[51] 5 rand Jan van Riebeeck and diamonds Mining and Johannesburg city centre Purple English and Afrikaans 127×63
[52] 10 rand Jan van Riebeeck and protea Agriculture Green Afrikaans and English 133×70
[53] 20 rand Jan van Riebeeck, Cape Dutch architecture and vines Jan van Riebeeck's three ships and Coat of Arms of South Africa Brown English and Afrikaans 140×77
[54] 50 rand Jan van Riebeeck and lion Fauna and flora Red Afrikaans and English 147×83
### Fourth series
Banknotes of the South African rand (1992 Fourth Issue "Big Five")[42][55]
Image Value Obverse Reverse Colour Language Size (mm)
[56] 10 rand Rhinoceros Agriculture Green Afrikaans and English 128×70
[57] 20 rand Elephants Mining Brown English and Afrikaans 134×70
[58] 50 rand Lions Manufacturing Red Afrikaans and English 140×70
[59] 100 rand Cape buffaloes Tourism Blue English and Afrikaans 146×70
[60] 200 rand Leopards Transport and communication Orange Afrikaans and English 152×70
### Fifth series
Banknotes of the South African rand (2005 Fifth Issue "English & Other Official Languages")[42]
Image Value Obverse Reverse Colour Language Size (mm)
[61] 10 rand Rhinoceros Agriculture Green English, Afrikaans, Swati 128×70
[62] 20 rand Elephants Mining Brown English, Southern Ndebele, Tswana 134×70
[63] 50 rand Lions Manufacturing Red English, Venda, Xhosa 140×70
[64] 100 rand Cape buffaloes Tourism Blue English, Northern Sotho, Tsonga 146×70
[65] 200 rand Leopards Transport and communication Orange English, Sotho, Zulu 152×70
### Sixth series
Banknotes of the South African rand (2012 Sixth Issue "Nelson Mandela")[42]
Image Value Obverse Reverse Colour Language Size (mm)
[66] 10 rand Nelson Mandela Rhinoceros Green English, Afrikaans, Swati 128×70
[67] 20 rand Elephant Brown English, Southern Ndebele, Tswana 134×70
[68] 50 rand Lion Red English, Venda, Xhosa 140×70
[69] 100 rand Cape buffalo Blue English, Northern Sotho, Tsonga 146×70
[70] 200 rand Leopard Orange English, Sotho, Zulu 152×70
### Seventh series
Banknotes of the South African rand (2018 Seventh Issue "Mandela Centenary")
Image Value Obverse Reverse Colour Language Size (mm)
[71] 10 rand Nelson Mandela Young Mandela and his birthplace of Mvezo Green English, Afrikaans, Swati 128×70
[72] 20 rand Young Mandela and his home in Soweto Brown English, Southern Ndebele, Tswana 134×70
[73] 50 rand Young Mandela and the site of his capture near Howick Red English, Venda, Xhosa 140×70
[74] 100 rand Young Mandela and his place of imprisonment at Robben Island Blue English, Northern Sotho, Tsonga 146×70
[75] 200 rand Young Mandela and his statue at the Union Buildings Orange English, Sotho, Zulu 152×70
### Exchange rate
Current ZAR exchange rates
From Google Finance: AUD CAD CHF CNY EUR GBP HKD JPY USD INR NGN JPY
From Yahoo! Finance: AUD CAD CHF CNY EUR GBP HKD JPY USD INR NGN JPY
From XE.com: AUD CAD CHF CNY EUR GBP HKD JPY USD INR NGN JPY
From OANDA: AUD CAD CHF CNY EUR GBP HKD JPY USD INR NGN JPY
## Note
1. ^ From Zuid-Afrikaanse rand ("South African rand"); the ZA is a historical relic from Dutch, used because "SA" is allocated to Saudi Arabia.
## References
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3. ^ A General's Story: from an Era of War and Peace, Jannie Geldenhuys, Jonathan Ball, 1995, page 32
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31. ^ "Statement issued by the SARB Governor, Ms G Marcus on counterfeit notes in circulation". South African Reserve Bank. 21 April 2010. Retrieved 25 May 2010.
32. ^ "South Africa faulty 100-rand notes reported | Africa". BanknoteNews.com. 5 December 2010. Retrieved 5 September 2012.
33. ^ "South Africa shreds 3.6 million defective 100-rand notes | Africa". BanknoteNews.com. 20 May 2012. Retrieved 5 September 2012.
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41. ^ "#Madiba100 commemorative notes and coin have a new look and feel". IOL. 14 July 2018. Retrieved 16 July 2018.
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75. ^
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https://www.gamedev.net/forums/topic/518500-affecting-private-members/
|
# Affecting Private Members
## Recommended Posts
I am creating an object class for my game and well all its data is private(I am still not sure why people keep stuff private, my understanding is it's to keep them safe from being changed unless you want them to be changed), I am new to handling things this way and well I am creating functions to retrieve and change this members but It's getting quite unmanagable.. I am pretty sure I am doing thisn wrong, can someone tell me how to make this simpler?
class object
{
private:
D3DXVECTOR2 pos;
float dirAngle;
float rotAngle;
DWORD lastShoot;
public:
//constructors
object();
object(D3DXVECTOR2, float, float, float);
//Set position
void setPos(D3DXVECTOR2);
// This are the add or subtract functions
void sub_x(float);
void sub_y(float);
void sub_dir(float);
void sub_rot(float);
//This are the retrieve functions
float getDir();
float getRot();
float getLast();
};
object::object()
{
pos = D3DXVECTOR2(0.0f,0.0f);
dirAngle = 0;
rotAngle = 0;
lastShoot = 0;
}
object::object(D3DXVECTOR2 p,
float dir,
float rot,
float last)
{
pos = p;
dirAngle = dir;
rotAngle = rot;
lastShoot = last;
}
void object::setPos(D3DXVECTOR2 p)
{
pos = p;
}
//Change X
{
pos.x += x;
}
void object::sub_x(float x)
{
pos.x -= x;
}
//Change Y
{
pos.y += y;
}
void object::sub_y(float y)
{
pos.y += y;
}
//Change Dir
{
dirAngle += dir;
}
void object::sub_dir(float dir)
{
dirAngle -= dir;
}
//....
//Get Properties
float getDir()
{
return dirAngle;
}
float getRot()
{
return rotAngle;
}
float getLast()
{
return lastShoot;
}
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Your opinion about private members is correct. However the methods you made could be done real simpler(really if you need more operators like multiply/cross/dot). Here's my version of it. I'm not sure if the d3d9x lib comes with vector operations, else you might make a vector class.
class object
{
private:
D3DXVECTOR2 pos;
float dirAngle;
float rotAngle;
DWORD lastShoot;
public:
//constructors
object();
object(D3DXVECTOR2, float, float, float);
D3DXVECTOR2 &GetPos() { return pos; }
float &GetDirAngle() { return dirAngle; }
float &GetRotAngle() { return rotAngle; }
DWORD &GetLastShoot() { return lastShoot; }
};
int main()
{
object obj;
obj.GetPos() = Vector(0,0,0); // You might need some operator for this
obj.GetPos()+=p; // etc...
}
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Here are some tips:
1) Be consistent. Be consistent in everything you do. It will make managing your code so much easier. This means be consistent in your naming convention (either do [addX, subDir, getRot, etc.] or [add_x, sub_dir, get_rot, etc.], but don't do both of them!).
2) Don't be afraid of spelling the whole word out. getDir() and getRot() would make a lot more sense if they were getDirection() and getRotation().
3) (a) Think about something really should be private or public (or protected). Member variables are often made private because of abstraction. When someone is using your class, they don't care about the exact implementation details; that's for you to worry about, not them. That's why you split up the class into "public" and "private" parts. They want your class to do something for them, and as long as it does it, they don't care how it does it. Plus if you ever need to change the internal implementation of the class, you can still keep the public interface, which means that you can change/update your class without breaking existing code.
(b) Another reason for making members private is because sometimes changing one can have a rather large impact. For example, let's pretend you have a class that represents a 2D vector. It has three variables: x, y, and angle. x and y are the (x, y) coordinates of the vector, and angle is the angle the vector makes with the x-axis. If the variables were public and someone were to change x, that could potentially change angle too! So then you decide to make the variables private and use accessor methods (the getters/setters) so that if someone wants to change x, you can also change angle in the accessor method without the user having to worry about manually updating the angle.
4) Realize that your class isn't getting unmanageable (or if you really think it is, identify exactly what part(s) of it is/are unmanageable). Your class is pretty small, and you only have a few accessor methods. You'll be writing much bigger classes with a lot more accessor methods someday. Welcome to the world of programming. (But in terms of manageability, consider visitor's suggestion of renaming your functions. He makes a very good point.)
5) Read up on this. If you have a const object, you can only use its const member functions.
Your class is so simple that if I were you, I'd consider (note I said consider, as in think about it, not necessarily actually do it) making the variables public. However, I'm not entirely sure what you are trying to accomplish with your class, so only make the variables public if it makes sense.
About johan postma's post: Hmmm... I'd never thought of that. Cool. Anyway, there really isn't much difference from that code and just making the members public. Personally I'd prefer public members with meaningful, descriptive names over those types of functions. The reason being is getter methods are almost universally implemented in such a way that the variable is meant to be read, not written to. This breaks my #1 rule of being consistent.
[ninja'd++]
[Edited by - MikeTacular on December 20, 2008 12:18:14 PM]
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void add_x(float);void sub_x(float);void add_y(float);void sub_y(float);
These could probably be condensed to:
void move(D3DXVECTOR2)
The thing with making things private is not only to limit who can modify the values but also help the rest of the program not care what the members are at all. For this it might help to think about the class in terms of services that it provides (move) rather than in terms of manipulating the class members (add_x etc).
void add_dir(float);void sub_dir(float);void add_rot(float);void sub_rot(float);
For these you might need half the number of functions (substracting is the same as adding a negative value) and again you might rather call them after what they do (e.g rotate, turn) and not emphasize on the member variable that is affected (add_dir, add_rot).
//This are the retrieve functionsfloat getDir();float getRot();float getLast();
These should be marked as constant methods since calling them shouldn't modify the instance.
float getDir() const;
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I don't really understand how this works/what this does :S.
'class object
{
private:
D3DXVECTOR2 pos;
float dirAngle;
float rotAngle;
DWORD lastShoot;
public:
//constructors
object();
object(D3DXVECTOR2, float, float, float);
D3DXVECTOR2 &GetPos() { return pos; }
float &GetDirAngle() { return dirAngle; }
float &GetRotAngle() { return rotAngle; }
DWORD &GetLastShoot() { return lastShoot; }
};
int main()
{
object obj;
obj.GetPos() = Vector(0,0,0); // You might need some operator for this
obj.GetPos()+=p; // etc...
}'
About the creating a move function, good idea, something like this?
class object{private: D3DXVECTOR2 position; float direction_angle; float rotation_angle; DWORD time_since_last_shot; public: //constructors object(); object(D3DXVECTOR2, float, float, DWORD); //Set position void set_position(D3DXVECTOR2); // This are the add or subtract functions void move_forward(); void move_backward(); void direct_forward(); void direct_backward(); void turn_forward(); void turn_backward(); //This are the retrieve functions float get_direction() const; float get_rotation() const; float get_time_since_last_shot() const; float get_degrees_to_radians();};object::object(){ position = D3DXVECTOR2(0.0f,0.0f); direction_angle = 0; rotation_angle = 0; time_since_last_shot = 0;}object::object(D3DXVECTOR2 new_position, float new_direction, float new_rotation, DWORD new_time_since_last_shot){ position = new_position; direction = new_direction; rotation = new_rotation; time_since_last_shot = new_time_since_last_shot;}void object::set_position(D3DXVECTOR2 new_position){ position = new_position;}//Movevoid object::move_forward(){ position.x -= 2.0f * sin(direction * get_degrees_to_radians()); position.y -= 2.0f * cos(direction * get_degrees_to_radians());}void object::move_backward(){ position.x += 2.0f * sin(direction * get_degrees_to_radians()); position.y += 2.0f * cos(direction * get_degrees_to_radians());}//Directionvoid object::direct_right(){ direction -= 2.0f; if(direction < 0) direction += 360;}void object::direct_left(){ direction += 2.0f; if(direction > 360) direction -= 360;}//Rotationvoid object::turn_right(){ rotation -= 2.0f; if(rotation < 0) rotation += 360;}void object::turn_left(){ rotation += 2.0f; if(rotation > 360) rotation -= 360;}//Get Propertiesfloat get_direction() const{ return direction;}float get_rotation() const{ return rotation;}float get_time_since_last_shot() const{ return time_since_last_shot;}float get_degrees_to_radians() const{ return 13.14159f / 180.0f;}
I would like to combine move_forward/backward into one, something like 'move', and the turn_right/left and direct_right/left into 1, something like 'rotate'.
The way it's set up right now direction is used with the move function to change the object's position while rotation changes the sprite's rotation(I noticed something strange, if you add to direction you have to subtract from rotation that's why I am using two different variables... If I tried to use direction for both then the sprite would rotate at the opposite direction from where the object was heading)
How could I do this?
Some questions, a constant variable you can't reset right? Neither can you change its value in any way?(Adding, subtracting)
The suggestion to make my variables global, I am confused aren't global variables bad? Or just in big classes?
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Quote:
Original post by johan postmaYour opinion about private members is correct. However the methods you made could be done real simpler(really if you need more operators like multiply/cross/dot). Here's my version of it. I'm not sure if the d3d9x lib comes with vector operations, else you might make a vector class.class object{private: D3DXVECTOR2 pos; float dirAngle; float rotAngle; DWORD lastShoot; public: D3DXVECTOR2 &GetPos() { return pos; } float &GetDirAngle() { return dirAngle; } float &GetRotAngle() { return rotAngle; } DWORD &GetLastShoot() { return lastShoot; }};int main(){ object obj; obj.GetPos() = Vector(0,0,0); // You might need some operator for this obj.GetPos()+=p; // etc... }
Take a look at what you have written here, and then ask yourself whether you gain anything by making the variables private.
You aren't preventing them from being changed by other classes/functions, because they can assign whatever they like to the reference, you aren't hiding implementation details, because a reference must refer to an actual instance, and you can't have side-effects on modification, because you can't detect the modification.
Basically you have added a lot of boilerplate code for zero gain, and (at least in my opinion) at the cost of a lot of readability. Also don't forget that when debugging you probably have compiler optimisations turned off, in which case all these little functions won't be inlined.
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Yes, you cannot change a const variable. Which means if someone made a const object of your class, they would not be able to call the move() function on it because that would change the object in some way.
Woah, wait. Nobody said to make your variables global. Global and public are 2 very, very different things. A public variable is a variable stored within a class that can be directly access through an object of that class. A global is a variable that doesn't exist in a class, it exists globally. You don't have to have an object of a class to use a global variable. Public variables aren't always bad. In my complex number class, I made the real and imaginary parts of the complex number public. There are times when public variables are the best tool, and there are times when they are not.
As for the code that you don't understand, it works because it uses references. Wikipedia and the C++ FAQ Lite explain references better than I could. But I wouldn't use that code if I were you.
Now about combining your functions: what do you recognize in common between the functions? They're exactly the same, except for a +/-. What if you had something like this:
class Object{ public: // This moves the object in the direction it's already facing. // A positive displacement is forward, and a negative displacement // is backwards. void move(float displacement); // This moves the object according to the variable 'displacement'. // Essentially, just add it do your current position void move(D3DXVECTOR2 displacement); // This rotates the object theta degrees. Remember that a positive // rotation is a counterclockwise rotation. void rotate(float theta); float getAngle() const; D3DXVECTOR2 getPosition() const; private: // You could make the variables public. It's up to you. float angle; D3DXVECTOR2 position; // This really shouldn't be a member fuction, but I'm putting it here // just for this sample code float degreesToRadians(float degrees) const;};void Object::move(float displacement){ position.x += displacement * std::cos(degreesToRadians(angle)); position.y += displacement * std::sin(degreesToRadians(angle));}void Object::move(D3DXVECTOR2 displacement){ position += displacement; // The above is the same as doing: // position.x += displacement.x; // position.y += displacement.y;}void Object::rotate(float theta){ angle += theta;}float Object::getAngle() const{ return angle;}D3DXVECTOR2 Object::getPosition() const{ return position;}float Object::degreesToRadians(float degrees){ const float pi = 3.1415926535897932384626433832795f; return degrees * pi / 180.0f;}
Note I only have to store one angle and I now only have a few functions. If you wanted to move the object forward 10 units, you just call move(10.0f). If you want to move the object backwards 10 units, just call move(-10.0f). What do you think of my above code? Do you have any questions about it?
[disclaimer]
I haven't tested the code above, but I'm pretty sure it's right. I don't know how D3DXVECTOR2 operates, so you may have to adjust the code so it properly accesses the correct members
[/disclaimer]
I noticed you had swapped sin and cos in your move function. cos should be used for the x-axis, and sin should be used for the y-axis. Also, in my code, I didn't implement any functions to set the position and angle. I figured you would be able to do this fairly easily on your own.
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I do have a couple of trivial questions.
I am still wondering if a single rotation variable will do, as I mentioned before trying to use the same value with the movement calculation and the rotation calculation had the sprite rotate in the opposite direction from where it was heading(I had to make a second variable with an opposite value to the rotation's to apply on the rotation calculation.. they became direction and rotation respectively).
I noticed you didnt made a check when changing rotation if you had gone below 0 or over 360 degrees to set it back(+360 to 0, -0 to 360) is this because the compiler will do that for you? Like turning 380 degrees into 20/ 720 into 360..?
Won't such a large amount of numbers on the pi definition cause problems? The calculation is made quite often during the game.
class object{private: D3DXVECTOR2 position; float rotation; DWORD time_since_last_shot; public: //constructors object(); object(D3DXVECTOR2, float, DWORD); // This are the add or subtract functions void move(float); void rotate(float); //This are the retrieve functions D3DXVECTOR2 get_position() const; float get_rotation() const; DWORD get_time_since_last_shot() const; float degrees_to_radians();};object::object(){ position = D3DXVECTOR2(0.0f,0.0f); rotation = 0; time_since_last_shot = 0;}object::object(D3DXVECTOR2 new_position, float new_rotation, DWORD new_time_since_last_shot){ position = new_position; rotation = new_rotation; time_since_last_shot = new_time_since_last_shot;}//Movevoid object::move(float displacement){ position.x += displacement * cos(degrees_to_radians(rotation)); position.y += displacement * sin(degrees_to_radians(rotation));}//Directionvoid object::rotate(float theta){ rotation += theta; if(rotation < 0) rotation += 360; if(rotation > 360) rotation -= 360;}//Get PropertiesD3DXVECTOR2 get_position() const{ return position;}float get_rotation() const{ return rotation;}DWORD get_time_since_last_shot() const{ return time_since_last_shot;}float degrees_to_radians(degrees){ const float pi = 3.1415926535897932384626433832795f; return degrees * pi / 180.0f;}
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Yes, you're right, I should have included a check when rotating to wrap the angle from [0, 360] degrees. The computer/compiler will not do it automatically.
I'm still not sure why you had to use two angles. You shouldn't need more than one. I think maybe the problem came from using sin/cos incorrectly. Or possibly applying the angle incorrectly when rendering. You originally had
position.x -= 2.0f * sin(direction * get_degrees_to_radians()); // should be cos
position.y -= 2.0f * cos(direction * get_degrees_to_radians()); // should be sin
So I think that may have been the problem. Try your new code and see if you still have the same problem. If you do, then there is probably something wrong in your rendering step and we can take a look at that code.
Wait. The move function I wrote (which is in your new code) is for regular Cartesian coordinates, like this:
However, if you're working in 2D, you might be using screen coordinates, like this:
If you are using screen coordinates, then some adjustments will have to be made. Let me know if you are using screen coordinates and I'll help you out.
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Oh I am using screen coordinates.
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Ok, well I'm going to assume you want to keep the origin in the top left and have the positive y-axis going down. In that case, now it depends on what you want to consider a "positive" rotation. I can't remember what's considered as the "standard". Counterclockwise is the standard for regular Cartesian coordinates, but I'm not sure about screen coordinates. Anyway, I'll give you both. If you want positive rotation to be counterclockwise, do the following:
angle += theta; // for rotations
x += displacement * std::cos(degreesToRadians(angle)); // for moving
y -= displacement * std::sin(degreesToRadians(angle)); // for moving
If you want positive rotation to be clockwise, do the following:
angle += theta; // for rotations
x += displacement * std::cos(degreesToRadians(angle)); // for moving
y += displacement * std::sin(degreesToRadians(angle)); // for moving
The only real difference is the +/- for the y component. If you ever wonder how I derived this, just look up the trig odd/even identities and draw a few pictures of regular Cartesian coordinate rotations and screen coordinate rotations.
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Oh then that's it, I should have been using the first method(positive counter clockwise) that's why the sprite's rotation went opposite of the object's direction.
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https://socratic.org/questions/how-would-you-rank-the-atomic-radius-of-the-following-elements-from-largest-to-s
|
Chemistry
Topics
# How would you rank the atomic radius of the following elements from largest to smallest: Na^(+) , F^(-) , O^(2-), Al^(3+), Mg^(2+), N^(3-)?
Nov 28, 2015
${\text{N"^(3-) > "O"^(2-) > "F"^(-) > "Na"^(+) > "Mg"^(2+) > "Al}}^{3 +}$
#### Explanation:
The important thing to realize here is that all those ions are isoelectronic, which means that they same the same number of electrons, and thus the same electron configuration.
More specifically, all those ions have the electron configuration of neon, $\text{Ne}$, which is a noble gas.
As you know, atomic and ionic size is determined by the distance from the nucleus to the outermost electrons. Since all those species have their outermost electrons on the same energy level, $n = 2$ to be precise, you will have to look at effective nuclear charge.
The attraction between the outermost electrons and the nucleus is what ultimately determines the size of the ion. This implies that the more positive the nucleus is, the more attracted the outermost electrons will be.
This of course means that the outermost electrons will be closer to the nucleus.
In your case, the nucleus with the most protons will compress the energy levels of the electrons the most, which will result in the ion having the smallest size.
This means that ionic size will increase in the order ${\text{Al}}^{3 +}$, ${\text{Mg}}^{2 +}$, ${\text{Na}}^{+}$, ${\text{F}}^{-}$, ${\text{O}}^{2 -}$, ${\text{N}}^{3 -}$, since aluminium has the biggest atomic number and the nitrogen the smallest.
Therefore, the order you're looking for will be
${\text{N"^(3-) > "O"^(2-) > "F"^(-) > "Na"^(+) > "Mg"^(2+) > "Al}}^{3 +}$
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https://brilliant.org/discussions/thread/quadratics-and-their-graphs/
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×
# A simple proof ?
If $$f(x)$$ is a quadratic equation with $$2$$ real roots, prove that the points where the graph of $$y=f(x)$$ cuts the $$x-$$ axis are equidistant to every point on the symmetric axis of $$f(x)$$.
Note by Karthik Venkata
2 years, 6 months ago
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consider the function to be $F(x) = ax^2 + bx + c$ given that roots are real .... two cases arise
(1) * they are equal *
i.e they both lie on axis of symmetry and share the same point hence are equidistant.
(2) they are distinct
the formula for roots is given by $x = \frac{-b}{2a} + or - \frac{\sqrt{b^2-4ac}}{2a}$ ......... {1}
which shows that equal amounts of $\frac{\sqrt{b^2-4ac}}{2a}$ is added and subtracted from the axis of symmetry giving rise to the roots. {this tells that the x coordinates of roots are placed equally apart from axis of symmetry}
they lie on the same horizontal axis {implies y coordinate w.r.t point on axis of symmetry is same} hence roots are equidistant.
- 2 years, 5 months ago
You are really close to the actual proof, you just need to prove that the quadratic has its symmetric axis given by the plot of the equation $$x = \dfrac{-b}{2a}$$ in the $$xy$$ plane.
- 2 years, 5 months ago
oops i considered that to be true ........ we can write F(x) as $F(x) = (x+\frac{b}{2a} )^2 + \frac{b^2 - 4ac}{4 a^2}$ comparing this with the graph of $f(x) = x^2 + k$ which has symmetry at x=0 {the y axis} , after translation of $\frac{b}{2a}$ the symmetry shifts to $x=\frac{-b}{2a}$
- 2 years, 5 months ago
Well excellent proof Abhinav Raichur !
- 2 years, 5 months ago
thank you :)
- 2 years, 5 months ago
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https://developer.aliyun.com/article/399464
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# 《Two Dozen Short Lessons in Haskell》（二十一）在形式参数中使用模式匹配
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### 第二十一章 Patterns as Formal Parameters
1 The formula (x : xs) is equivalent to
a x ++ xs
b [x] ++ xs
c [x] ++ [xs]
d all of the above
2 The definition
HASKELL DEFINITION • f(x : xs) = g x xs
HASKELL DEFINITION • f [ ] = h
a defines h in terms of g
b defines f for arguments that are either empty or non-empty sequences
c will not work if xs is the empty sequence
d all of the above
3 The definition
HASKELL DEFINITION • f(x : xs) = g x xs
is equivalent to
a f xs | null xs = g x xs
b f xs = g x xs || h
c f xs | not(null xs) = g (head x) (tail xs)
d f x xs = g(x : xs)
4 Which of the following defines a function of type ([Char], Char) -> [Char] ?
a f( (x : xs), ’x’ ) = [x] ++ reverse xs ++ [’x’]
b f( x , y : ys ) = [ ] ++ reverse ys ++ [x]
c f( (xs : ’x’), x ) = [x] ++ reverse xs ++ [’x’]
d all of the above
5 Which of the following formulas delivers every third element of the sequence xs?
a foldr drop [ ] xs
b [ foldr drop [ ] suffix | suffix <- iterate (drop 3) xs ]
c [ x | (x : suffix) <- takeWhile (/= [ ]) (iterate (drop 3) (drop 2 xs)) ]
d takeWhile (/= [ ]) (iterate (take 3) xs)
=============================
=============================
1 b
2 b
3 c
4 a
b选项不仅仅应用于([Char],Char)，还可以应用于其它类型，f :: (a, [a]) -> [a]
c中的(xs:’x’)应该是无法匹配的，根据reverse xs ++ [’x’]，可以推断xs是[Char]，这样(xs:’x’)里的'x’就应该是[[Char]]类型，所以会报语法错。
5 c
http://www.cnblogs.com/speeding/
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https://wiki.math.ucr.edu/index.php/Implicit_Differentiation
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# Implicit Differentiation
## Background
So far, you may only have differentiated functions written in the form ${\displaystyle y=f(x)}$. But some functions are better described by an equation involving ${\displaystyle x}$ and ${\displaystyle y}$. For example, ${\displaystyle x^{2}+y^{2}=16}$ describes the graph of a circle with center ${\displaystyle \left(0,0\right)}$ and radius 4, and is really the graph of two functions ${\displaystyle y=\pm {\sqrt {16-x^{2}}}}$, the upper and lower semicircles:
Sometimes, functions described by equations in ${\displaystyle x}$ and ${\displaystyle y}$ are too hard to solve for ${\displaystyle y}$, for example ${\displaystyle x^{3}+y^{3}=6xy}$. This equation really describes 3 different functions of x, whose graph is the curve:
We want to find derivatives of these functions without having to solve for ${\displaystyle y}$ explicitly. We do this by implicit differentiation. The process is to take the derivative of both sides of the given equation with respect to ${\displaystyle x}$, and then do some algebra steps to solve for ${\displaystyle y'}$ (or ${\displaystyle {\dfrac {dy}{dx}}}$ if you prefer), keeping in mind that ${\displaystyle y}$ is a function of ${\displaystyle x}$ throughout the equation.
## Warm-up exercises
Given that ${\displaystyle y}$ is a function of ${\displaystyle x}$, find the derivative of the following functions with respect to ${\displaystyle x}$.
1) ${\displaystyle y^{2}}$
Solution:
${\displaystyle 2yy'}$
Reason:
Think ${\displaystyle y=f(x)}$, and view it as ${\displaystyle (f(x))^{2}}$ to see that the derivative is ${\displaystyle 2f(x)\cdot f'(x)}$ by the chain rule, but write it as ${\displaystyle 2yy'}$.
2) ${\displaystyle xy}$
Solution:
${\displaystyle xy'+y}$
Reason:
${\displaystyle x}$ and ${\displaystyle y}$ are both functions of ${\displaystyle x}$ which are being multiplied together, so the product rule says it's ${\displaystyle x\cdot y'+y\cdot 1}$.
3) ${\displaystyle \cos y}$
Solution:
${\displaystyle -y'\sin y}$
Reason:
The function ${\displaystyle y}$ is inside of the cosine function, so the chain rule gives ${\displaystyle (-\sin y)\cdot y'=-y'\sin y}$.
4) ${\displaystyle {\sqrt {x+y}}}$
Solution:
${\displaystyle {\frac {1+y'}{2{\sqrt {x+y}}}}}$
Reason:
Write it as ${\displaystyle (x+y)^{\frac {1}{2}}}$, and use the chain rule to get ${\displaystyle {\frac {1}{2}}\left(x+y\right)^{-{\frac {1}{2}}}\cdot \left(1+y'\right)}$, then simplify.
## Exercise 1: Compute y'
Find ${\displaystyle y'}$ if ${\displaystyle \sin y-3x^{2}y=8}$.
Note the ${\displaystyle \sin y}$ term requires the chain rule, the ${\displaystyle 3x^{2}y}$ term needs the product rule, and the derivative of 8 is 0.
We get
${\displaystyle {\begin{array}{rcl}\sin y-3x^{2}y&=&8\\\left(\cos y\right)y'-\left(3x^{2}y'+6xy\right)&=&0\quad ({\text{derivative of both sides with respect to }}x)\\\left(\cos y\right)y'-3x^{2}y'&=&6xy\\\left(\cos y-3x^{2}\right)y'&=&6xy\\y'&=&{\dfrac {6xy}{\cos y-3x^{2}}}.\end{array}}}$
## Exercise 2: Find equation of tangent line
Find the equation of the tangent line to ${\displaystyle x^{2}+2xy-y^{2}+x=2}$ at the point ${\displaystyle \left(1,0\right)}$.
We first compute ${\displaystyle y'}$ by implicit differentiation.
${\displaystyle {\begin{array}{rcl}x^{2}+2xy-y^{2}+x&=&2\\2x+2xy'+2y-2yy'+1&=&0\\x+xy'+y-yy'+{\frac {1}{2}}&=&0\\xy'-yy'&=&-x-y-{\frac {1}{2}}\\(x-y)y'&=&-(x+y+{\frac {1}{2}})\\y'&=&-{\dfrac {x+y+{\frac {1}{2}}}{x-y}}\end{array}}}$
At the point ${\displaystyle \left(1,0\right)}$, we have ${\displaystyle x=1}$ and ${\displaystyle y=0}$. Plugging these into our equation for ${\displaystyle y'}$ gives
${\displaystyle {\begin{array}{rcl}y'&=&-{\dfrac {1+0+{\frac {1}{2}}}{1-0}}=-{\frac {3}{2}}.\\\end{array}}}$
This means the slope of the tangent line at ${\displaystyle \left(1,0\right)}$ is ${\displaystyle m=-{\frac {3}{2}}}$, and a point on this line is ${\displaystyle \left(1,0\right)}$. Using the point-slope form of a line, we get
${\displaystyle {\begin{array}{rcl}y-0&=&-{\frac {3}{2}}\left(x-1\right)\\\\y&=&-{\frac {3}{2}}x+{\frac {3}{2}}.\\\end{array}}}$
Here's a picture of the curve and tangent line:
## Exercise 3: Compute y"
Find ${\displaystyle y''}$ if ${\displaystyle ye^{y}=x}$.
Use implicit differentiation to find ${\displaystyle y'}$ first:
${\displaystyle {\begin{array}{rcl}ye^{y}&=&x\\ye^{y}y'+y'e^{y}&=&1\\y'\left(ye^{y}+e^{y}\right)&=&1\\y'&=&{\dfrac {1}{ye^{y}+e^{y}}}\\&=&\left(ye^{y}+e^{y}\right)^{-1}\end{array}}}$
Now ${\displaystyle y''}$ is just the derivative of ${\displaystyle \left(ye^{y}+e^{y}\right)^{-1}}$ with respect to ${\displaystyle x}$. This will require the chain rule. Notice we already found the derivative of ${\displaystyle ye^{y}}$ to be ${\displaystyle ye^{y}y'+y'e^{y}}$.
So
${\displaystyle {\begin{array}{rcl}y''&=&-1\left(ye^{y}+e^{y}\right)^{-2}\left(ye^{y}y'+y'e^{y}+e^{y}y'\right)\\\\&=&{\dfrac {-1}{\left(ye^{y}+e^{y}\right)^{2}}}\left(ye^{y}y'+2y'e^{y}\right)\\\\&=&-{\dfrac {y'e^{y}\left(y+2\right)}{\left(e^{y}\right)^{2}\left(y+1\right)^{2}}}\\\\&=&-{\dfrac {y'\left(y+2\right)}{e^{y}\left(y+1\right)^{2}}}\quad ({\text{since }}e^{y}\neq 0).\end{array}}}$
But we mustn't leave ${\displaystyle y'}$ in our final answer. So, plug ${\displaystyle y'={\dfrac {1}{e^{y}\left(y+1\right)}}}$ back in to get
${\displaystyle {\begin{array}{rcl}y''&=&-{\dfrac {{\frac {1}{e^{y}\left(y+1\right)}}\left(y+2\right)}{e^{y}\left(y+1\right)^{2}}}\\\\&=&-{\dfrac {y+2}{\left(e^{y}\right)^{2}\left(y+1\right)^{3}}}\end{array}}}$
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http://smarteiffel.loria.fr/man/short.html
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Wiki FAQ Lib doc. Tools doc. Mailing list Bug reports Papers Download SCM Inria People Home (http) Home
The short Command
The short command is the SmartEiffel interface generator. Using a plain Eiffel source file, the short command prints on the standard output the interface of this class. The short command is also a good tool to performs many validity checks of a given class (syntax, exportation rules, inheritance, etc.). There are two invocation modes: traditional and ACE.
Note that features from ANY are not printed unless the class you are shorting is ANY or feature from ANY is redefined.
Usage
se short [format] [options] <Class>
ACE mode
se short [format] [options] <ACEfile.ace> <Class>
The short command prints on the standard output the interface of the given <Class>.
The default format is -plain: no special characters are added.
The short command is customisable and some predefined formats are already available (see below for predefined formats and how to add a new output format). When ACE mode is used, as usual, the "loadpath.se" is ignored and only the content of the ACE file is used to look for the Eiffel source code.
Options
-help:
Display a brief summary of the command-line syntax and a complete list of compiler options.
-verbose:
Print system information during the compilation (full path of files loaded, type inference score, removed files, etc.).
-version:
Display the version number of the SmartEiffel release you're using.
Adds a loadpath file for class lookup. See details in the finder man page.
-sort:
Features are sorted alphabetically.
-short:
Does not consider inherited features.
-no_style_warning:
Suppress output for warning messages related to non respect of standard Eiffel style guidelines (for example ItEm will not trigger a warning).
-no_warning:
Suppresses output for all warning messages (error messages are still printed). Implies -no_style_warning.
-client <client_class>:
Specify the class whom the point of view is taken of. This command allow to know all features visible to client_class from the class you short.
Note1: default is equivalent to -client ANY.
Note2: se short -client class class does not show all features from class, only features exported to itself are printed (callable via qualified calls).
-all_clients:
To display all features even those which are not exported.
Predefined Output Formats
-plain:
The default compact output format. No special character added.
-pretty:
Basically, it is similar to -plain except that there are a couple of additional line-feeds (e.g. between features) that make the structure of the output easier to read. (It sort of appears like the "pretty" printer would have done it, that's why "-pretty").
-tex1:
Simple output mode for TeX. Encloses the interface in a simple verbatim TeX environment.
-tex2:
Output mode for TeX. Uses a TeX alltt environment with a \bf font for keywords, \it font for comments and \tt font for identifiers.
-tex3:
Output mode for TeX. Follows style guidelines given in ETL appendix A. As the previous mode, this mode also uses a TeX alltt environment.
-html1:
A nice HTML output (provided by Matthias Klose).
-html2:
Another nice HTML output too. This one is the one used to generate the library interface of the SmartEiffel WEB site.
-html_css:
A nice HTML+CSS output (provided by John E. Perry). The CSS file is seshort.css.
To define a new output format, you have to add a new sub-directory in the SmartEiffel "short" directory. In order to change the output, this new directory must contains various hook files, which contain text used to replace the default output.
Here is the current list of hook files.
1. Changing the output for the class interface header
"hook000" - If this hook file exists, the contents of this file is printed very first.
"hook010" - If this hook file exists, and if the processed class is an expanded one, the contents of this file is printed before the class name to replace the default string "expanded class interface ".
"hook011" - If this hook file exists, and if the processed class is an deferred one, the contents of this file is printed before the class name to replace the default string "deferred class interface ".
"hook012" - If this hook file exists, and if the processed class is an ordinary one (not deferred nor expanded) the contents of this file is printed before the class name to replace the default string "class interface ".
"hook013" _ If this hook file exists, the contents of this file is printed before the class name whatever the kind of class (expanded, deferred or ordinary) to replace the default empty string "".
"hook014" - If this hook exists, the contents of the file is printed after the class name to replace the default string "%N".
"hook015" - If this hook file exists, and if a class header comment is present, this file is printed once before the heading class comment.
"hook016" - If this hook file exists, and if an heading comment is present, the contents of this file is printed to replace the default string " --" at the beginning of each comment line.
"hook017" - If this hook file exists, and if an heading comment is present, the contents of this file is printed to replace the default string "%N" at the end of each comment line.
"hook018" - If this hook file exists, and if a class heading comment is present, the contents of this file is printed once after the heading comment.
"hook019" - If this hook file exists, and if the processed class has no heading comment, this file is printed once.
2. Changing the output for the creation list
"hook100" - If it exists, this file is printed before the creation list to replace the default string "creation%N".
"hook101" - If it exists, this file is printed after the creation list to replace the default empty string "".
"hook102" - If it exists, this file is printed when the class has no creation list.
3. Changing the output for the feature list
"hook200" - If exists, printed before the feature list when option -sort is selected to replace the default string "feature(s)%N".
"hook201" - If exists, printed after the feature list when option -sort is selected to replace the default empty string "".
"hook202" - If exists, printed before each feature list with no heading comment to replace the default string "feature(s) from ".
"hook203" - If exists, printed after the class name of "hook202" to replace the default string "%N".
"hook204" - If exists, printed before a feature list with a heading comment to replace the default string "feature(s) from ".
"hook205" - If exists, printed after the class name introduced at "hook204" to replace the default string "%N".
"hook206" - If exists, printed before each line of the feature list comment to replace the default string " --".
"hook207" - If exists, printed after each line of the feature list comment to replace the default string "%N".
"hook208" - If exists, printed after a feature list comment to replace the default empty string "".
4. Changing the output for a feature signature
"hook300" - If this hook exists, the contents of this file is printed before each feature to replace the default string " ".
"hook301" - If this hook exists, the contents of this file is printed once when the feature has no arguments to replace the default empty string "".
"hook302" - If this hook exists, the contents of this file is printed once when the feature has arguments to replace the default string " (".
"hook303" - If this hook exists, the contents of this file is printed when the feature has arguments to replace the default string " ;".
"hook304" - If this hook exists, the contents of this file is printed when the feature has arguments to replace the default string ", ".
"hook305" - If this hook exists, the contents of this file is printed when the feature has arguments to replace the default string ": ".
"hook306" - If this hook exists, the contents of this file is printed once when the feature has arguments to replace the default string ")".
"hook307" - If this hook exists, the contents of this file is printed once when the feature has no result to replace the default string "%N".
"hook308" - If this hook exists, the contents of this file is printed once before the result type of the feature to replace the default string ": ".
"hook309" - If this hook exists, the contents of this file is printed once after the result type of the feature to replace the default string "%N".
5. Changing the output for a feature comment
"hook310" - If this hook file exists, and if a feature has a heading comment, this file is printed once before the comment.
"hook311" - If this hook file exists, and if a feature has a heading comment, the contents of this file is printed to replace the default string " --" at the beginning of each comment line.
"hook312" - If this hook file exists, and if a feature has a heading comment, the contents of this file is printed to replace the default string "%N" at the end of each comment line.
"hook313" - If this hook file exists, and if a feature has a heading comment, the contents of this file is printed once after this comment.
"hook314" - If this hook file exists, and if a feature has no heading comment, the contents of this file is printed.
"hook315" - If this hook file exists, and if a feature is deferred, the contents of this file is printed.
6. Changing the output for require clauses
6.1. For the header of a require clause
"hook400" - If this hook file exists, and if a feature has no require assertion, the contents of this file is printed to replace the default empty string "".
"hook401" - If this hook file exists, and if a feature has one require assertion, the contents of this file is printed before the latest inherited assertion to replace the default string " require%N".
"hook402" - If this hook file exists, and if a feature has more than one require assertion, the contents of this file is printed before the require assertion to replace the default string " require else%N".
"hook403" - If this hook file exists, and if a feature has at least one require assertion, the contents of this file is printed to finish the job (once after the last printed require assertion) to replace the default empty string "".
"hook412" - If exists, printed when a require clause has no heading comment to replace the default empty string "".
"hook413" - If exists, printed once before the require clause heading comment to replace the default empty string "".
"hook414" - If exists, printed before each line of the heading comment to replace the default string " --".
"hook415" - If exists, printed after each line of the heading comment to replace the default string "%N".
"hook416" - If exists, printed once after the require clause heading comment.
"hook417" - If exists, printed when a require clause has no assertion to replace the default empty string "".
"hook418" - If exists, printed once before the first assertion of a require clause to replace the default empty string "".
"hook433" - If exists, printed once after the last assertion of a require clause to replace the default empty string "".
"hook434" - If exists, printed to finish a require clause to replace the default empty string "".
6.2. For each assertion in a require clause
"hook419" - If exists, printed before each assertion of a require clause to replace the default string " ".
"hook420" - If exists, printed when an assertion has no tag to replace the default empty string "".
"hook421" - If exists, printed before a tag to replace the default empty string "".
"hook422" - If exists, printed after a tag to replace the default string ": ".
"hook423" - If exists, printed when the assertion has no expression to replace the default empty string "".
"hook424" - If exists, printed before the expression to replace the default empty string "".
"hook425" - If exists, printed after the expression (except for the last assertion) to replace the default string ";".
"hook426" - If exists, printed when an assertion has no comment to replace the default string "%N".
"hook427" - If exists, printed once before the assertion comment to replace the default empty string "".
"hook428" - If exists, printed before each line of the expression comment to replace the default string " --".
"hook429" - If exists, printed after each line of the expression comment to replace the default string "%N".
"hook430" - If exists, printed once after the assertion's comment to replace the default string "".
"hook431" - If exists, printed after the assertion to replace the default empty string "".
6.3. For the last assertion in a require clause
Same hook file list as described in section 6.2 except "hook425" which becomes :
"hook432" - If exists, printed after the last expression to replace the default empty string "".
7. Changing the output for ensure clauses
7.1. For the header of the ensure clause
"hook500" - If this hook file exists, and a feature has no ensure clause, the contents of this file is printed to replace the default empty string "".
"hook511" - If this hook file exists, the contents of this file is printed before each ensure clause to replace the default string " ensure%N".
"hook512" - If exists, printed when ensure clause has no heading comment to replace default empty string "".
"hook513" - If exists, printed once before the ensure clause heading comment to replace the default empty string "".
"hook514" - If exists, printed before each line of the heading comment to replace the default string " --".
"hook555" - If exists, printed after each line of the heading comment to replace the default string "%N".
"hook516" - If exists, printed once after the ensure clause heading comment.
"hook517" - If exists, printed when an ensure clause has no assertion to replace the default empty string "".
"hook518" - If exists, printed once before the first assertion of the ensure clause to replace the default empty string "".
"hook533" - If exists, printed once after the last assertion of the ensure clause to replace the default empty string "".
"hook534" - If exists, printed to finish the ensure clause to replace the default empty string "".
7.2. For each assertion in the ensure assertion
"hook519" - If exists, printed before each assertion of the ensure clause to replace the default string " ".
"hook520" - If exists, printed when an assertion has no tag to replace the default empty string "".
"hook521" - If exists, printed before a tag to replace the default empty string "".
"hook522" - If exists, printed after a tag to replace the default string ": ".
"hook523" - If exists, printed when the assertion has no expression to replace the default empty string "".
"hook524" - If exists, printed before the expression to replace the default empty string "".
"hook525" - If exists, printed after the expression (except for the last assertion) to replace the default string ";".
"hook526" - If exists, printed when an assertion has no comment to replace the default string "%N".
"hook527" - If exists, printed once before the assertion comment to replace the default empty string "".
"hook528" - If exists, printed before each line of the expression comment to replace the default string " --".
"hook529" - If exists, printed after each line of the expression comment to replace the default string "%N".
"hook530" - If exists, printed once after the assertion's comment to replace the default string "".
"hook531" - If exists, printed after the assertion to replace the default empty string "".
7.3. For the last assertion in the ensure clause
Same hook files list as described in section 7.2 except "hook525" which becomes :
"hook532" - If exists, printed after the last expression to replace the default empty string "".
8. Changing the output after each feature
"hook599" - If exists, printed after each feature to replace the default empty string "".
9. Changing the output for the class invariant
9.1. For the header of the class invariant
"hook800" - If this hook file exists, and when no class invariant exists, the contents of this file is printed to replace the default empty string "".
"hook811" - If this hook file exists, the contents of this file is printed before the class invariant to replace the default string "invariant%N".
"hook812" - If exists, printed when class invariant has no heading comment to replace default empty string "".
"hook813" - If exists, printed once before the invariant heading comment to replace the default empty string "".
"hook814" - If exists, printed before each line of the heading comment to replace the default string " --".
"hook855" - If exists, printed after each line of the heading comment to replace the default string "%N".
"hook816" - If exists, printed once after the invariant heading comment.
"hook817" - If exists, printed when class invariant has no assertion to replace the default empty string "".
"hook818" - If exists, printed once before the first assertion of the class invariant to replace the default empty string "".
"hook833" - If exists, printed once after the last assertion of the class invariant to replace the default empty string "".
"hook834" - If exists, printed to finish the class invariant to replace the default empty string "".
9.2. For each assertion in the class invariant
"hook819" - If exists, printed before each assertion of the class invariant to replace the default string " ".
"hook820" - If exists, printed when an assertion has no tag to replace the default empty string "".
"hook821" - If exists, printed before a tag to replace the default empty string "".
"hook822" - If exists, printed after a tag to replace the default string ": ".
"hook823" - If exists, printed when the assertion has no expression to replace the default empty string "".
"hook824" - If exists, printed before the expression to replace the default empty string "".
"hook825" - If exists, printed after the expression (except for the last assertion) to replace the default string ";".
"hook826" - If exists, printed when an assertion has no comment to replace the default string "%N".
"hook827" - If exists, printed once before the assertion comment to replace the default empty string "".
"hook828" - If exists, printed before each line of the expression comment to replace the default string " --".
"hook829" - If exists, printed after each line of the expression comment to replace the default string "%N".
"hook830" - If exists, printed once after the assertion's comment to replace the default string "".
"hook831" - If exists, printed after the assertion to replace the default empty string "".
9.3. For the last assertion in the class invariant
Same hook files list as described in section 9.2 except "hook825" which becomes :
"hook832" - If exists, printed after the last expression to replace the default string ";".
10. Changing the output for the class interface footer
"hook900" - When exists, printed once before class footer to replace the default empty string "".
"hook901" - When exists, printed once at the end of an expanded class before the class name to replace the default "end of expanded ".
"hook902" - When exists, printed once at the end of a deferred class before the class name to replace the default "end of deferred ".
"hook903" - When exists, printed once at the end of an ordinary (not expanded nor deferred) class, before the class name to replace the default string "end of ".
"hook904" - When exist, printed just before the class name to replace the default empty string "".
"hook905" - When exists, the contents of this file is printed after the class name to replace the default string "%N".
"hook999" - If this hook file exists, the contents of this file is printed once to finish the job.
11. Class name and formal generic arguments
11.1 Changing the output for class names
"Bcn" - When exists, printed Before each class name.
"Mcn" - When exists, the corresponding class name is printed one more time (using lower case letters) just before the contents of this hook file.
"Acn" - When exists, printed After each class name.
"Ucn" - To replace the Underscore character in a class name.
11.2 Changing the output for formal generic arguments
"Bfga" - When exists, printed Before each formal generic argument.
"Mfga" - When exists, the corresponding formal generic argument is printed one more time (using lower case letters) just before the contents of this hook file.
"Afga" - When exists, printed After each formal generic argument.
"Ufga" - To replace the Underscore character in a formal generic argument.
12. Changing the output for a type mark
"Btm" - When exists, printed Before each type mark.
"Atm" - When exists, printed After each type mark.
"open_sb" - To replace the opening square bracket (default "[").
"close_sb" - To replace the closing square bracket (default "]").
"fgl_sep" - To replace the default comma ", " in a formal generic argument list.
"tm_blank" - To replace a blank character in a type mark.
"tm_sep" - To replace default string ", " as a separator in a generic list.
"like" - To replace the default string "like ".
"expanded" - To replace the default string "expanded ".
13. Changing the output for feature names
13.1. Simple feature names
"Bsfn" - When exists, printed Before each Simple Feature Name.
"Asfn" - When exists, printed After each Simple Feature Name.
"Usfn" - To replace the underscore character in a simple feature name.
13.2. Infix feature names
"Bifn" - When exists, replaces the default string "infix %"" Before an infix feature name definition.
"Aifn" - When exists, replaces the default string "%"" to close "Bifn".
"Binfix" - When exists, replaces the default string " " printed before the infix name used in an expression.
"Ainfix" - When exists, replaces the default string " " printed after the infix name used in an expression.
"rem" - When exists, replaces the default string "\\".
13.3. Prefix feature names
"Bpfn" - When exists, replaces the default string "prefix %"" Before a prefix feature name definition.
"Apfn" - When exists, replaces the default string "%"" to close "Bpfn".
14. Changing the output for an argument name
"Ban" - When exists, printed Before each argument name.
"Aan" - When exists, printed after each argument name.
"Uan" - To replace the Underscore character in an argument name.
15. Changing the output for a tag name
"Btag" - When exists, printed Before each tag name.
"Atag" - When exists, printed after each tag name.
"Utag" - To replace the Underscore character in a tag name.
16. Changing the output for an effective argument list
"op_eal" - To replace the default string "(" to open an effective argument list.
"eal_sep" - To replace the default string ", " in an effective argument list.
"cl_eal" - To replace the default string ")" for an effective argument list.
17. Changing the output for manifest strings
"open_ms" - To replace the default opening string "%"".
"close_ms" - To replace the default closing string "%"".
"Prcnt_ms" - To replace a % character inside a manifest string.
"Slash_ms" - To replace a / character inside a manifest string.
18. Changing the output for a manifest array
"op_ma" - To replace the default string "<<" to open a manifest array.
"ma_sep" - To replace the default string ", " in a manifest array.
"cl_ma" - To replace the default string ">>" to close a manifest array.
19. Changing the output for comments lines
"BECL" - Before Each Comment Line. This hook is applied to all comments whatever the kind of comment. If exists, printed before the contents of each line of each comment (usually after the default string "--").
"AECL" - After Each Comment Line. This hook is applied to all comments whatever the kind of comment. If exits, printed after the contents of each line of each comment (usually, printed before the default "%N").
"Ucomment" - To replace the Underscore character in a comment.
"op_quote" - To replace the default opening quote mark "`".
"cl_quote" - To close an "op_quote" to replace the closing quote mark "'".
20. Miscellaneous tuning
"open_b" - To replace the default opening bracket "(" in expressions.
"close_b" - To replace the default closing bracket ")" in expressions.
"arrow" - To replace the default string "->" in a formal generic list.
"dot" - To replace the default string "." in an expression.
"Result" - To replace the default string "Result".
"old" - To replace the default string "old " in ensure clauses.
"strip_open" - To replace the default string "strip (".
"strip_close" - To replace default string ")" which closes "strip_open".
"create_open" - To replace the default string "create {".
"create_close" - To replace default string "}" which closes "create_open".
"fnl_sep" - To replace the default string ", " in a feature name list.
"Current" - To replace the default string "Current".
"Void" - To replace the default string "Void".
"once" - To replace the default string "once ".
"new_line" - To replace the default string "%N".
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https://studyqueries.com/how-to-learn-kanji/
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How To Learn Kanji? A Beginner’s Ultimate Guide
How To Learn Kanji? In a similar way, not learning kanji is like cooking a meal without all the seasonings that make it delicious. Your meal is still edible and provides you with the energy you need to continue your day. However, do you find it enjoyable in any way and would you recommend it to your friends? Unfortunately, no. While you do not need to learn kanji to get by, learning kanji will definitely help you gain a better understanding of the Japanese language and make your life in Japan easier.
In the beginning, many Japanese learners complain that learning Kanji is difficult. Kanji can be difficult to understand at first, but that does not diminish its importance. There is widespread use of kanji in Japan. There are examples of this on menus, signs, and even in names. It is therefore not sufficient to be able to speak Japanese or read hiragana if you plan to live in Japan for an extended period of time.
Furthermore, if you intend to work in Japan in the future, you must be familiar with kanji. Now that we have established the importance of kanji, let’s discuss the best method for learning it. This article will provide you with some great kanji study tips so you can stop stressing about them when you are next confronted with them.
The Kanji character is only one part of a much larger and more complex Japanese language. If you have not already done so, we recommend visiting our Guide to Japanese Adjectives and Guide to Japanese Conjugation.
How To Learn Japanese Kanji In The Best And Fast Way
Memorization Through Repetition
Repetition is the key to learning any language. Just about anything can be learned through rote memorization, like flashcards or reading notes over and over. Reading and writing down kanji (and their meaning) over and over again is a great way to study. For beginners, this is a great way to start learning kanji.
You could also practice stroke order with easy-to-write kanji. In this lesson, you’ll learn how to read kanji and how recognize radicals. You’ll also learn how kanji look and how they sound based on whether they’re associated with another kanji. You won’t get stressed out when you see the same kanji again!
Using Mnemonics
Another way to learn kanji is with mnemonics. Many kanji textbooks use this method to help students memorize kanji. I was taught kanji with this method as a beginner and it helps me memorize certain kanji. Kanji are pictures of the words they represent.
It’s hard to figure out what each kanji represents just by looking at it, since kanji were created centuries ago. Using a picture to associate kanji with its meaning is one of the best ways to learn them. Here are a few examples of how to use a picture to explain kanji.
• $$田 (だ/da)$$ : Rice Field
• $$川 (かわ/kawa)$$: River
• $$山 (やま/yama)$$: Mountain
• Learn $$常用漢字$$ (Jouyou Kanji)
In Japanese society, jouyou kanji are commonly used kanji. In Japan, children are taught this type of kanji. You can learn kanji by studying jouyou kanji. Some of the kanji on the list are commonly used and easy to write. Furthermore, the strokes are not too difficult, making them easy to remember. A few of these kanji are $$肉(にく$$/niku/meat), $$国-くに$$/kuni/country), and $$子 -こ$$/ko/child).
Knowing this type of kanji will be helpful when you begin reading Japanese newspapers, signs, books, and other reading materials. However, you will at least be familiar with a few popular kanji that will make reading easier. You might even be able to guess the meaning of words you don’t understand. In Japanese textbooks such as the Genki textbook, jouyou kanji can be found. Online lists can also be found easily.
Are you aware that we offer highly engaging online Japanese textbooks for beginners? To prepare you for your next encounter with kanji, we will cover some of the most commonly used kanji.
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Learn The Kanji For The Words You Use The Most
This kanji tip encourages you to study kanji you might use in everyday conversations but aren’t included in Jouyou kanji.
Electronics (printers, headphones, etc.), decorative items in the home (curtains, vases, lamps), and words specific to a career field. You might be able to communicate better with Japanese friends and family if you learn more kanji for words you use regularly.
By learning kanji like these, you’ll be able to expand your vocabulary and knowledge of kanji. Try using kanji to spice up your conversation with a Japanese pen pal.
Maybe you just wanna understand what your penfriend is saying without having to constantly ask them what the kanji means. Whatever you do, learning the kanji you’ll use regularly is a smart way to learn Japanese.
There’s no doubt that you’ve noticed a pattern in the kanji you’ve learned. You’ve seen these trends related to the radical, which is the main component of kanji. Radicals can be found left, right, above, or below kanji.
Kanji can also be surrounded by them. You can guess the meaning of the kanji by understanding the radical. See for yourself. Observe how the radicals are used to interpret a kanji’s meaning.
$$読$$ (yo)
The radical is $$言$$. This is located on the left and means to say. As a result, the kanji refers to speaking. $$読$$ means to read.
$$悪$$ (aku)
The radical is $$心$$. It refers to the heart or mind. Hearts and minds are not literally referred to in this phrase. It is more metaphorical in nature. At the bottom is radical. Hence, the kanji represents the heart. $$悪$$ (aku) means bad.
Being able to recognize and understand kanji is a valuable skill when you begin reading more Japanese literary content. For beginners to the Japanese language, it is impossible to know the meanings and pronunciations of each of the kanjis that are used by the Japanese.
When they see unfamiliar kanji, even native Japanese speakers look them up. It is possible to improve your reading speed and comprehension of a text by understanding the meaning of radicals. Despite guessing the wrong meaning, your Japanese friends will enjoy it at the very least.
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Take Your Vocabulary List To The Next Level With Kanji
You can broaden your kanji studies even more by learning the kanji on your vocabulary list. It’s probably not a surprise to you that Japanese textbooks like Genki have kanji lists for each chapter. Here’s the order of the strokes, their meanings, and their pronunciations.
A kanji that gets this much attention is usually considered important and is regularly used. Having said that, textbooks like Genki also provide plenty of vocabulary words without a detailed chart showing kanji writing and other words using the same kanji.
Like kids who don’t get invited to parties but have all the coolest party tricks. The party will always be fun, even if you don’t see them very often.
Study the kanji and your word list. Besides helping you learn more kanji, it will also help you memorize your vocabulary words. Your use of grammar principles will probably increase as you learn the grammar principles and complete the writing activities for each chapter.
The kanji for each word should also be studied if you have made your own vocabulary list. In order to read Japanese books, signs, newspapers, and other reading material better, you must learn more kanji.
It can be tedious to create your own vocabulary list. Our Ultimate Guide to Learning Japanese Vocabulary covers everything you need to know.
Become Familiar With Japanese Reading Material
A language must be read in order to be learned. You probably heard this from your English teachers every day. No matter where you are from or what language you speak, you must be able to read and write. Reading and writing can only be improved by doing more of them.
You might be thinking, “I can’t!” “I don’t know enough kanji.” or “It’s too difficult.” “I have to translate everything.” You might be right in part, but not entirely. The goal is to motivate yourself to learn more about kanji and understand how they are used in writing, so you may not recognize every kanji you encounter.
It will take some time for you to become proficient at reading Japanese. It took you a long time, but you persevered and now you’re an expert in it.
Alternatively, you might have read beginner-level material that was easy to understand and had easy-to-pronounce words. The process of learning kanji is no different. You can improve your understanding of kanji by reading materials that match your proficiency level.
You can start reading children’s material if your proficiency level is N5. Two manga that is easy to read for beginners includes kanji reading: Yotsuba and Shirokuma Cafe. You should definitely check them out.
In addition, if you are reading online, use the Google Chrome browser extension rikaichan. When you hover over words with your mouse, it translates the kanji. Hovering over kanji will also provide you with information about them. All Japanese language learners should use this extension when reading Japanese.
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It is important to use a dictionary when learning any foreign language. If you do not know the meaning of a word, you should be able to search for its translation easily. Studying Japanese is particularly challenging. You might also want to look up words that use similar kanji if you do not know the word. If you learn kanji, you will gain a better understanding of its meaning.
If you don’t have access to a digital dictionary, it can be difficult to look things up. However, if you know how to spell the word in hiragana, it’s relatively easy. See if the surrounding words use the same romanized kanji as the romanized kanji. There should be a lot of words that use the same kanji and you should be able to comprehend the meaning of all the related kanji.
Therefore, we highly recommend that you buy or download a dictionary if you don’t already have one. If you don’t have one, you can’t study Japanese efficiently or effectively.
Make Sure You Practice The Stroke Order
Is it difficult for you to remember the pronunciation and meaning of a kanji but not its appearance? Many Japanese language learners experience this problem. If you answered yes, you aren’t alone. It seems that many people are more likely to remember the meaning and pronunciation of a kanji if they are looking at it. When they do not see the kanji, however, it becomes significantly more challenging.
There is a connection between this phenomenon and how people study. Using flashcards to study the meaning and pronunciation of kanji is a common method of studying Japanese. Stroke order, however, is overlooked in this study method.
By learning the stroke order of a kanji, you’ll be able to remember how it looks. Additionally, you will gain more confidence when you encounter two kanji with similar pronunciations and will be able to determine which one to use. The fact that you’ve seen and read about how to operate a car doesn’t mean you know how to drive it. It is always easier to remember some things when you actually do them.
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Get To Practice With Your Pen Pals
Although some may consider writing kanji to be the most boring and time-consuming method of learning kanji, it is probably the most effective method of memorizing kanji. Try making it more engaging, interactive, and fun if you fall into this category. Starting a pen pal relationship would be a good first step.
Writing to a pen pal is a great way to improve your grammar and spelling skills. You can also use it to remember vocabulary words and kanji. You will find yourself using some kanji over and over again.
By repeating kanji, you become more engaged when you talk to someone, resulting in better recall. If you are looking for a pen pal, check out HelloTalk. Our Ultimate Guide to Japanese Learning Apps will give you more useful tools for your learning journey if you’re searching for something more specific.
By Studying Compound Kanji, You Can Learn Kanji
Despite our previous discussion, studying kanji alone can be a bit of a letdown. Trying to memorize a kanji while muttering the meaning and pronunciation of the word, you stare at it. Due to the lack of context, it is hard to remember just one character by itself.
If you walk into an argument, the first thing you hear is, “It wasn’t my fault!” It’s like trying to make sense of the conversation. “I barely touched the elephant!” It may take you a while to realize that the argument is about who spooked the elephants during a previous visit.
The process of learning kanji is similar to that of learning English. This is probably due to the fact that kanji are typically parts of words. In addition to their own meanings and pronunciations, they are often accompanied by hiragana or another kanji. Check out the kanji in the picture below.
Make sure you read the meanings of each kanji separately.
Use Flashcards
Flashcards are a tried-and-true way to study. On the other hand, people who make their own Japanese flashcards write the word in Japanese on one side and the English equivalent on the other. I think this is a good idea. It works, but you’ll need to know a few more things when studying kanji. We’ve got you covered with White Rabbit flashcards.
There’s no comparison between White Rabbit flashcards and the old standard flashcards. These flashcards have English translations of everything on the card, as well as stroke order, kanji that seem similar, and other words using the same kanji. Despite having a lot of information on one card, it doesn’t look cluttered. There are three levels of difficulty for flashcards: beginner, intermediate, and advanced. There’s so much information in White Rabbit flashcards that they’re great for studying kanji.
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Apps For Learning Kanji
Apps are always a great option when it comes to studying. There are apps for learning autonomy, math, and coding. There must be some kanji apps out there. Kanji Study is one of those apps. There are hundreds of kanji to study in this app – from Elementary 1 to Advanced. You can also learn about radicals with this program.
The Japanese Kanji Study lets you study kanji in depth by analyzing characters, explaining radicals, and using words in sentences. The stroke order of the kanji can also be shown along with the various terms that use it. The app is free on Android, but you’ll have to pay a one-time fee to access most of it.
You can also learn Japanese with JLPT: Japanese Study Kanji Vocabulary N5 N4 N3 N1. With this app, you can learn more than kanji. While studying for the Japanese Language Proficiency Test (JLPT), you can practice your vocabulary and grammar. An appealing interface makes the app easy to use. There’s also a free version of this software in the Google Play Store, but you have to buy a subscription to get access to the full app.
Learn Kanji With These Books
You can also learn kanji through books if you don’t like apps. These books include kanji displaying stroke order and strategies for recalling kanji. Kanji can even be memorized using visuals. In order to study kanji, many students use Remembering the Kanji: A Full Course on How Not to Forget the Meaning and Writing of Japanese Characters.
Even though it doesn’t have visuals like Kanji Pict-O-Graphix, another kanji book, it does describe how the kanji appears, so you can imagine the kanji in your head. You can get the book on Amazon in paperback or Kindle.
Get Into Calligraphy
If you’re an artist or want to branch out from learning kanji, calligraphy might be for you. Calligraphy is known as $$書道$$ -$$しょどう$$ (shodo) in Japanese and you may already be familiar with it. There have probably been videos of people meticulously writing characters with a brush dipped in ink on thin white rice paper. There’s something graceful about it, and the result is always stunning. Having tried it a few times, I found it to be relaxing and peaceful.
If you do try out $$書道$$, you may quickly discover how messy it can be. Use several layers of newspaper or construction paper behind the rice paper to keep the ink from bleeding onto the hard surface below. Rice paper is super thin. You might even want to wear an old shirt and pants in case you spill ink. You can always buy calligraphy pens if you want a less messy alternative.
Write down the meaning of the kanji you studied in a corner of the paper first. This part can be done with a regular pen. After that, draw the kanji that matches the meaning with an inkbrush or calligraphy pen. Make sure you use the right stroke order. Make sure you got it right once you’re done.
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FAQs
Is kanji difficult to learn?
Japanese kanji, the boogeyman of the language, is actually pretty simple. In addition to making it easier to learn kanji (through spaced repetition systems), technology has also made reading and writing kanji easier. You don’t have to remember the stroke order of each kanji anymore; just type it in!
How long does it take to learn kanji?
What’s the average time it takes to learn Kanji? We calculate that you should be able to read kanji within three months if you learn 25 kanji a day. The first time you saw kanji was probably when you decided to learn Japanese.
How many kanji should a beginner learn?
People say you have to learn around 2000 kanji to be fluent in Japanese. For example, Japanese people must know 2136 government-mandated joyo kanji. Similarly, you have to know 2000 kanji to pass the N1 level of the JLPT.
Is Japanese kanji easy?
Kanji looks complicated, and it takes time to learn – a high school graduate needs to know 10,000 different characters! It doesn’t require talent, though. There’s good news for those who are scared to learn Kanji: it’s logical.
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Conclusion
Kanji can be hard to learn. Now it doesn’t have to be. You’ve learned two of the best ways to study kanji, along with how to get started. Besides apps and activities, you know a few ways to make studying interesting. That’s why you don’t need to worry. It’s fun dragging your brush over thin rice paper or joking around with a pen pal.
When it comes to mastering Japanese conversation, your vocabulary is just as important as your kanji. Learn how to survive any Japanese conversation with our guide Guide to Top 1000 Japanese Words You Need to Know!
How To Learn And Writing Japanese – A Beginner’s Ultimate Guide
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http://www.talkstats.com/threads/standard-deviation.4723/
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standard deviation
saige30
New Member
I have a problem I'm struggling to figure out how to compute....could someone walk me though the problem and explain how to figure out the answer? I'm really not even sure where to start on these types of problems. Thanks!
problem: The average sales representative for Insmed pharmaceutical company earns $124,000 in sales incentives with a standard deviation of$32,000. Assuming that the salaries are normally distributed, 90% of teh salaries will be above what dollar mark?
Last edited:
Dragan
Super Moderator
I have a problem I'm struggling to figure out how to compute....could someone walk me though the problem and explain how to figure out the answer? I'm really not even sure where to start on these types of problems. Thanks!
problem: The average sales representative for Insmed pharmaceutical company earns $124,000 in sales incentives with a standard deviation of$32,000. Assuming that the salaries are normally distributed, 90% of teh salaries will be above what dollar mark?
Use the Z-tranformation: Z = (X - Mu)/Sigma.
You know that Mu = 124, Sigma = 32, and from the Z-table Z = -1.28. Solving for X we obtain X = 32*(-1.28) + 124= your answer...(multiply your answer times 1000 to get the dollar amount).
saige30
z score
thanks so much...my answer is 90% of scores will be over $83,040. Is that correct? also- I knew equation already, but I wasn't sure how to find the zscore. I have the table in my book, but my professor didn't discuss how to use it. Can you offer any help there? THanks! Dragan Super Moderator I have the table in my book, but my professor didn't discuss how to use it. Can you offer any help there? THanks! Your question would be much easier for me to address if I had your textbook and then I could just (simply) show you....but I don't. How about this...Why not ask your professor to show you how to use the table(s) - since it seems to be the case that you're being required to solve these problems. saige30 New Member i would if only he had office hours from when he assigned the practice through tomorrow (our test) but he's out of the office thanks though for your help!! Mean Joe TS Contributor problem: The average sales representative for Insmed pharmaceutical company earns$124,000 in sales incentives with a standard deviation of \$32,000. Assuming that the salaries are normally distributed, 90% of teh salaries will be above what dollar mark?
You want the area under the curve = .90. This is a one-tail problem; the z-score corresponding to a tail area of .10 is z=1.282 BUT since we want the area ABOVE the value, we use z=-1.282
(Look at your insurance problem where they wanted to cover 85% BELOW the specific value and you used the positive z. Understand when to use positive z and when to use negative z? You won't get the right answer if you don't.)
Using the formula (for one-tail): z = (x - mean) / stdev, we can solve x=82,976.
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https://www.physicsforums.com/threads/momentum-of-two-objects.138693/
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# Homework Help: Momentum of two objects
1. Oct 16, 2006
### map7s
Object 1 has a mass m1 and a velocity 1 = (2.78 m/s) in the x direction. Object 2 has a mass m2 and a velocity 2 = (3.21 m/s) in the y direction. The total momentum of these two objects has a magnitude of 16.8 kgm/s and points in a direction 66.5° above the positive x-axis. Find m1 and m2.
I tried doing p=mv for each one but it didn't work. I think that it has something to do with the resulting angle, but I don't know how to incorporate that into the equation.
2. Oct 16, 2006
### jamesrc
Write a little more about what you did. You should be trying to break up the total momentum into x and y components (using trigonometry). Then you can equate the momentum of object 1 with the component of the total momentum in the x-direction and the momentum of object 2 with the component of the total momentum in the y-direction.
3. Oct 16, 2006
All you have to do is solve the vector equation: $$\vec{p} = \vec{p}_{1} + \vec{p}_{2}$$, where p is the total momentum, and p1 and p2 are the momentum of masses 1 and 2, respectively.
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https://brilliant.org/problems/palindrome-rooted-polynomial/
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# 'Palindrome' rooted polynomial.
Algebra Level 4
$x^8 + 2x^6 + 2x^5 + 2x^4 + 2x^3 + 2x^2 + x = 6039306$
Find sum of all the integer solutions to the equation above.
×
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http://www.ck12.org/tebook/Basic-Speller-Teacher-Materials/r1/section/5.2/
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<meta http-equiv="refresh" content="1; url=/nojavascript/"> Lesson two | CK-12 Foundation
You are reading an older version of this FlexBook® textbook: Basic Speller Teacher Materials Go to the latest version.
# 5.2: Lesson two
Created by: CK-12
## Review of Elements, Simple Addition, and Compound Words
1. Elements are the smallest parts of written words that add meaning to the words. There are three kinds of elements: prefixes, bases, and suffixes.
Prefixes are elements that go at the front of words and cannot stand free as words. Un- and re- are prefixes in the words unpainted and remixing.
Bases are elements that can have prefixes and suffixes added at the front and back.
Free bases are bases that can stand free as words, like the bases paint and mix in the words unpainted and remixing.
Suffixes are elements that go at the end of words and cannot stand free as words. In the words unpainted and remixing,-ed and -ing are suffixes.
2. The Rule of Simple Addition. Unless you know some reason to make a change, when you add elements together to spell a word, do not make any changes at all. Simply add the elements together.
Add the following prefixes and suffixes to the free bases to spell words. All of the elements combine according to the Rule of Simple Addition:
Prefix + Free Base + Suffix = Word
un + friend + ly = unfriendly
un + fail + ing = unfailing
re + move + s = removes
re + search + er = researcher
un + arm + ed = unarmed
re + arm + ing = rearming
un + finish + ed = unfinished
re + finish + ed = refinished
un + trust + ing = untrusting
re + act + ing = reacting
3. Now try some the other way around. Analyze each of the following words into its elements. Most contain a prefix. All contain a free base and a suffix:
Word = Analysis
unmixed = un + mix + ed
remixing = re + mix + ing
searches = search + es
losses = loss + es
redrawing = re + draw + ing
undoctored = un + doctor + ed
genies = genie + s
4. Compound Words. Words like somebody that are made up of two or more shorter words are called compound words, or just compounds.
Divide each of the following words into two parts. In some words Part 1 is a prefix and Part 2 is a free base. In some words Part 1 is a free base and Part 2 is a suffix. Some of the words are compounds in which both Part 1 and Part 2 are free bases.
Word Part 1 Part 2
searchlight search light
remove re move
strikeout strike out
gathered gather ed
landfill land fill
inchworm inch worm
roaster roast er
trusted trust ed
rewrap re wrap
birdcage bird cage
youths youth s
mixer mix er
Write the five compound words from the table above into these boxes: . . .
$searchlight && strikeout && landfill && inchworm && birdcage$
In each of the five compounds did the shorter words combine through simple addition?
Yes
Nearly all compound words combine by simple addition
Teaching Notes.
Item 1. Elements, bases, and suffixes are introduced in Book 1, Lesson 28. Prefixes are introduced in Book 2, Lesson 40.
Item 2. The Rule of Simple Addition is introduced in Book 1, Lesson 30.
Item 3. Compounds are introduced in Book 1, Lesson 31. They are also discussed in Book 2, Lessons 13-14, 38-39.
## Subjects:
1 , 2 , 3 , 4 , 5
## Date Created:
Feb 23, 2012
Apr 29, 2014
You can only attach files to None which belong to you
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https://physics.stackexchange.com/questions/309789/dependence-of-fluid-pressure-being-on-height-and-not-mass
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# Dependence of fluid pressure being on height and not mass
Fluid pressure is calculated as
$$\rho = hdg$$
where $\rho$ is fluid pressure, $h$ is depth from surface, $d$ is density of fluid and $g$ is acceleration of gravity.
It used to make sense to me for square or rectangle shaped containers since pressure means force per unit area.
$$Pressure = \frac{Force}{Area} = \frac{Fluid \space Weight}{Container's \space Bottom \space Area}$$
and
$$h \times d \times g= \frac{h\times m \times g}{v} = \frac{h\times m \times g}{h \times s} = \frac{m \times g}{s} = \frac{Fluid \space Weight}{Container's \space Bottom \space Area}$$
where $m$ is mass, $v$ is volume and $s$ is bottom area.
I thought that pressure being dependent on $h$ and not $m$ would be acceptable since $m$ is also dependent on $h$ since fluids can't go higher when they have spaces to their sides.
One big obvious mistake I made was to assume that all containers would be squares or rectangles. So, now I can't wrap my mind around the concept that pressures on tennis balls in the following image are equal.
Why are they equal when the weight (and mass) of fluid above them is obviously different?
• PS: I found a very similar question on the site before asking the question and I even took the image from there however, OP of that question asks something slightly different based on a thought experiment and it hasn't got an answer that answers my question so please don't mark as duplicate. – SarpSTA Feb 4 '17 at 23:33
• Pressure is weight over surface. Is this ratio really higher in the picture on the right? Why would that be the case? – Phoenix87 Feb 4 '17 at 23:41
• In the left diagram, you can think of the situation as a ball in a little cubical chamber being pressurized by a long, heavy piston with a small cross-sectional area (i.e., the narrow column of water). In the right diagram, you have the another ball in a cubical chamber but now the chamber is pressurized by an even heavier piston than the the one on the left AND this heavier piston also has a larger cross-sectional area than the piston on the left. So which chamber has a higher pressure? Sure, the piston on the right is pushing with more force, but that force is pushing over a larger area. – Samuel Weir Feb 4 '17 at 23:56
What you have ignored is the effect of the container walls.
The liquid is in equilibrium each particle has no net force on it.
Whatever force the liquid above a small region of the liquid exerts on that region a region of the liquid at the same horizontal level has the same force exerted by the container wall.
So the region of liquid has the same force on it irrespective of whether there is liquid or a container wall above it.
So your analysis failed to include the contribution to the force due to the container wall.
Make a hole in the wall and the force due to the wall ceases to exist and liquid comes out of the hole.
Let us consider the picture you provided(remove the tennis balls,they're useless here), and at a certain depth $h$ from the free surface of both tanks, connect them by another pipe as shown.
NOTE:both the free surfaces of the tanks are at the same distance from the pipe,which is horizontal.
If possible, let us assume that the pressures at the given depth $h$ is different in the tanks. Then water would flow from the right to the left(under the assumption that greater mass implies greater pressure). Also assume after transportation, no water is spilled over the brim of the tanks. Now, at equilibrium the horizontal pipe is at a distance of $h_1$ from the free surface of left tank and at $h_2$ from free surface of right tank($h_1 > h_2$). Consider a infinitesimally small fluid cube A of side $dh$ in the left tank, at the same level as the pipe. Let the force here be $\vec F = F_x + F_y + F_z$.
Clearly under equlibrium(taking z axis to be vertical):
$(F_x + dF_x)-F_x = 0$.............1)
$(F_y + dF_y) -F_y = 0$............2)
$(F_z + dF_z) - F_z = dV.\rho.g$.....3)[$dV = dA.dh$ is the volume of the fluid element.]
Clearly,from 1) and 2), we can see that $dP_x = \frac{dF_x}{dA} = 0$ and similarly, $dP_y = 0$
From 3), we have $dF_z = \rho.g.dA.dh$
or, integrating $P_z = \rho.g.h + C$ Clearly, $C = P_a$ (atmospheric pressure)
So, for the left tank, $P_z = \rho.g.h_1 + P_a$, while for the right tank it is
$P_z = \rho.g.h_2 + P_a$ [Assuming change in $P_a$ is negligible over $h_1 - h_2$.
But this means that the pressures are not equal at the same depth in the left and right tanks, and neither are the forces on the fluid elements. Thus, there will be further flow to attain equilibrium, net force on the fluid elements should be zero. This contradicts the assumption that equilibrium had been reached at $h_2$ and $h_1$. Hence, our primary assumption must also be false. i.e: there cannot be any water flow when we initially connect the pipes. Thus the pressures must also be equal at the same depth, whatever the shape of the tank.
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https://space.stackexchange.com/questions/38595/delta-v-cost-of-longitudinal-plane-change-correction
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# Delta-v cost of longitudinal plane change correction?
In a recent question, the slow drift of a landing site on a rotating body relative to an orbiter came up.
This would sometimes require a plane change correction when one desires to recover the landing party.
What would the $$\Delta v$$ cost of such a maneuver be?
Some initial considerations:
• The landing site does not uniquely define a plane. While the latitude sets a minimum inclination, the inclination of the orbiter's initial orbit may very well be larger.
• Similarly, an entire family of planes are possible for the pickup orbit. Optimisation would require picking the closest one.
• Landing from an equatorial orbit would never require a plane change, and neither will a polar landing.
• When the initial inclination is low and/or the stay is short, the cost is low.
• For all configurations of inclination and latitude, there would be no need for a plane change exactly twice during the body's rotation.
• While the plane change can usually be done as a simple impulse, that's not always optimal. I would imagine calculation just the inclination change angle instead of the velocity change would be simpler
While not exactly a hairy problem, the 3-dimensional geometry is not quite trivial, so it would be nice to have an answer to this for future reference.
• While not in the spirit of the question, if launching from Earth, just wait 24 hours for the Earth to rotate back into the same position. That's what Soyuz 6, 7, and 8 did. Launched each 24 hours, 6 took movies of the attempted docking of 7 and 8. They then landed at about the same spot in 24 hour intervals. Zero delta-v required. – DrSheldon Sep 6 '19 at 12:04
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https://math.stackexchange.com/questions/2315998/check-that-operator-is-linear-transformation-and-find-matrix-in-the-same-basis
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Check that operator is linear transformation and find matrix in the same basis
Now I have:
$$\varphi\mathbf{x}=(x_2+x_3,2x_1+x_3,3x_1-x_2+x_3)$$
How do I check that this transformation is linear, and Also find its matrix?
As about matrix, the basis is not given, so it should be standard one: $$e_1=\langle1,0,0\rangle, e_2=\langle0,1,0\rangle, e_3=\langle0,0,1\rangle$$
As far as I know I have to put all the components into the matrix, like:
$$A =\begin{pmatrix}x_2+x_3 \\ 2x_1+x_3 \\ 3x_1-x_2+x_3 \end{pmatrix}$$
But I do not know how to proceed with given $e_{1,2,3}$ basis.
$$A_{\varphi} = \begin{pmatrix} 0 & 1 & 1 \\ 2 & 0 & 1 \\ 3 & -1 & 1 \end{pmatrix}$$
But asd I've said above, I do not know how to get the right result
• First tell what is the definition space and what the codomain...! And "to find its matrix"...with respect to what basis ? – DonAntonio Jun 9 '17 at 12:35
• @Bye_World Good...and I guess the space is $\;\Bbb R^3\;$ both as domain and codomain. Let us let him confirm. Poor worded questions cause problems... – DonAntonio Jun 9 '17 at 12:39
• @Bye_World And I don't see why you keep on intervening if the OP hasn't even said half a word, and I don't care who and why gave him the question: it is still a poorly worded one. Shall we wait until the OP address the questions or you intend to continue writing? – DonAntonio Jun 9 '17 at 12:41
On linearity
In general, to show that a function $T:V\to W$ between real vector spaces $V$ and $W$ is linear, you need to show that it is
• Homogeneous. I.e. for all $\mathbf v\in V$ and for all $k\in \Bbb R$, $T(k\mathbf v) = kT(\mathbf v)$.
• Additive. I.e. for all $\mathbf v_1, \mathbf v_2 \in V$, $T(\mathbf v_1+\mathbf v_2) = T(\mathbf v_1) + T(\mathbf v_2)$.
In this particular case, showing homogeneity means proving (or disproving) that for all real $k$: $$\varphi(k\mathbf x) = \varphi\big(k(x_1,x_2,x_3)\big) = k\varphi(\mathbf x)$$ and showing additivity means (dis)proving that $$\varphi(\mathbf x +\mathbf y) = \varphi\big((x_1,x_2,x_3)+(y_1,y_2,y_3)\big) = \varphi(\mathbf x) + \varphi(\mathbf y)$$
On the Matrix Representation
Hint:
$$A =\begin{pmatrix}x_2+x_3 \\ 2x_1+x_3 \\ 3x_1-x_2+x_3 \end{pmatrix} = \pmatrix{ 0x_1 + 1x_2 + 1x_3 \\ 2x_1+0x_2+1x_3 \\ 3x_1-1x_2+1x_3}$$
Does that help?
• Aha. it explains the second part of question, first one is still unclear, how to check if transformation is linear or not – M.Mass Jun 9 '17 at 12:43
• See if my edit helps. – user137731 Jun 9 '17 at 12:59
I suppose that the transformations acts on the vector space $\mathbb{R}^3$ (over $\mathbb{R}$). If so you can prove linearity showing that: $$\varphi(\mathbf x+a\mathbf y)=\varphi (\mathbf x)+a\varphi(\mathbf y) \quad \forall a\in\mathbb{R} \quad and \quad \forall \mathbf x,\mathbf y\in\mathbb{R}^3$$
This is simple using the definition and the properties of addition and multiplication in $\mathbb {R}$.
To show that the matrix that you have found represents the transformation simply verify that:
$$A_{\varphi}\mathbf x^T =[\varphi (\mathbf x)]^T$$ That is obvious $$\begin{pmatrix} 0 & 1 & 1 \\ 2 & 0 & 1 \\ 3 & -1 & 1 \end{pmatrix}\begin{pmatrix} x_1 \\ x_2 \\ x_3 \end{pmatrix}=\begin{pmatrix} x_1+x_2 \\ 2x_1+x_3 \\ 3x_1-x_2+x_3 \end{pmatrix}$$
To find the matrix of a linear transformation $T$ with respect to the standard basis, first you have to know which space $T$ is going from (the "domain") and which space $T$ is sending vectors to (the "codomain"). Here you can see that the vectors in the domain have 3 components (they are $x_1,x_2,$ and $x_3$), and (if we're working with just real numbers, as is typical), and that the outputs have three components. So $T$ is a linear transformation from $\mathbb{R}^3$ to $\mathbb{R}^3$. What you do is you find $T(e_1)$, $T(e_2)$, and $T(e_3)$. Those appear as the columns of the matrix.
So in this example, $T(e_1)=(0,2,3)$ (you just plug in $x_1=1,x_2=0,x_3=0$). This goes in the first column. Then find $T(e_2)$. That goes in the 2nd column. Then find $T(e_3)$. That goes in the third column.
How to check something is a linear transformation:
Let's review what the term linear transformation means. If $V$ and $W$ are vector spaces, a linear transformation from $V$ to $W$ is a map $T$ from $V$ to $W$ such that for every two scalars $c$ and $d$, and every two vector $v_1$ and $v_2$ in $V$, $T(cv_1+dv_2)=cT(v_1)+dT(v_2)$.
(If you're taking linear algebra, it would be a good idea to memorize this.)
As Bye_World says, you can also break this down into two criteria. First, check that for every single scalar $c$ and every single vector $v$ in $V$, $T(cv)=cT(v)$. Then check that for every two vectors $v_1$ and $v_2$ in $V$, $T(v_1+v_2)=T(v_1)+T(v_2)$. I'm going to walk you down how I would do the first thing to check. In parentheses I'll write down my mental picture.
If $\textbf{v}=(v_1,v_2,v_3)$ and $c$ is any scalar, does $T(c\textbf{v})=cT(\textbf{v})$?
(I have to convert the thing on the left of the equals sign to the thing on the right. First I'll write $c\textbf{v}$ in coordinates:)
$c(v_1,v_2,v_3)=(cv_1,cv_2,cv_3)$.
(Now I need to plug that into $T$. They tell you what $T$ does, so I use that.)
$T(cv_1,cv_2,cv_3)=(cv_2+cv_3, 2cv_1+cv_3, 3cv_1-cv_2+cv_3)$.
(OK. Now I'm trying to check that this is equal to $cT(\textbf{v})$. Let me write that in coordinates.)
$cT(\textbf{v})=cT(v_1,v_2,v_3)=c(v_2+v_3,2v_1+v_3,3v_1-v_2+v_3) ... (So I rewrote the left hand side out and I rewrote the right hand side and I have to now check that I got the same thing. You can see that this is the same by distributing the$c$across)$=(cv_2+cv_3,2cv_1+cv_3,3cv_1-cv_2+cv_3)$. (Now conclude:) So$T(c\textbf{v})=cT(\textbf{v})$. That's how you do the first part of checking that something is a linear transformation. I'll let you do the second part. By the way, what, in words, is going on? Think of$T$as a function, except instead of taking numbers to other numbers (like$f(x)=x^2$), it takes vectors to other vectors. The condition that$T(c\textbf{v})=cT(\textbf{v})$can be visualized. If$\textbf{v}$was a purple vector, then$T(\textbf{v})$is where the purple vector goes. The statement says that, any scalar multiple of the purple vector goes to the corresponding scalar multiple of where the purple vector goes. So for instance, 2 times the purple vector has to go to 2 times where the purple vector goes, etc. I think some linear algebra students find this explanation helpful. • Technically we don't know that$\operatorname{dom} \varphi = \Bbb R^3$, it's just implied (which is why Don was getting all bent out of shape in the comments). It could very well be$\varphi(x_1,x_2,x_3,x_4)=\dots$where the map just doesn't use$x_4$. But good answer. +1 I like how you walked the reader through the proof that$T(cv) = cT(v)\$. Just a note on formatting, tho. If you add double dollar signs instead of single ones you get $$\text{Math Mode}$$ which can help break up your answer a little more so it doesn't look like such a wall of text. Not a big deal tho. As I said, good answer. – user137731 Jun 9 '17 at 13:27
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https://www.rdocumentation.org/packages/base/versions/3.6.2/topics/chol2inv
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# chol2inv
0th
Percentile
##### Inverse from Choleski (or QR) Decomposition
Invert a symmetric, positive definite square matrix from its Choleski decomposition. Equivalently, compute $(X'X)^{-1}$ from the ($R$ part) of the QR decomposition of $X$.
Keywords
algebra, array
##### Usage
chol2inv(x, size = NCOL(x), LINPACK = FALSE)
##### Arguments
x
a matrix. The first size columns of the upper triangle contain the Choleski decomposition of the matrix to be inverted.
size
the number of columns of x containing the Choleski decomposition.
LINPACK
logical. Defunct and ignored (with a warning for true value).
##### Value
The inverse of the matrix whose Choleski decomposition was given.
Unsuccessful results from the underlying LAPACK code will result in an error giving a positive error code: these can only be interpreted by detailed study of the FORTRAN code.
##### References
Anderson. E. and ten others (1999) LAPACK Users' Guide. Third Edition. SIAM. Available on-line at http://www.netlib.org/lapack/lug/lapack_lug.html.
Dongarra, J. J., Bunch, J. R., Moler, C. B. and Stewart, G. W. (1978) LINPACK Users Guide. Philadelphia: SIAM Publications.
chol, solve.
library(base) # NOT RUN { cma <- chol(ma <- cbind(1, 1:3, c(1,3,7))) ma %*% chol2inv(cma) # }
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http://artofmemory.com/wiki/Chisanbop
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# Chisanbop
Chisanbop or chisenbop (from Korean chi (ji) finger + sanpŏp (sanbeop) calculation[1] 지산법) is an abacus-like finger counting method used to perform basic mathematical operations. According to The Complete Book of Chisanbop[2] by Hang Young Pai, chisanbop was created in the 1940s in Korea by Sung Jin Pai and revised by his son Hang Young Pai. It was brought to the U.S. around 1977 by Hang Young Pai. With this method it is possible to display all numbers from 0 to 99 with two hands.
## Basic concepts
The hands are held in a relaxed posture on or above a table. All fingers are floating off the table to begin with. The fingers are pressed into the table to indicate value.
Each finger (but not the thumb) of the right hand has a value of one. Press the index finger of the right hand onto the table to indicate "one." Press the index and middle fingers for "two", the three leftmost fingers for "three", and all four fingers of the right hand to indicate "four".
The thumb of the right hand holds the value "five". To place the value "six", press the right thumb and index finger onto the table. The thumb indicates "five" plus the "one" indicated by the finger.
The left hand represents the tens digit. It works like the right hand, but each value is multiplied by ten. Each finger on the left hand represents "ten", and the left thumb represents "fifty". In this way, all values between zero and ninety-nine can be indicated on two hands.
## Notation
A proposed notation system for representing the numbers:
. = a finger off the table
o = a finger on the table
- = a thumb off the table
@ = a thumb on the table
Values between zero and 9 are shown with the entire right hand:
-.... = 0
@oooo = 9
@ooo. = 8
@oo.. = 7
@o... = 6
@.... = 5
-oooo = 4
-ooo. = 3
-oo.. = 2
-o... = 1
Values larger than 10 are shown with both hands:
..oo- @.... = 25
....@ @.... = 55
oooo- -.... = 40
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https://www.science.gov/topicpages/a/al+cu+ta.html
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#### Sample records for al cu ta
1. A new type of Cu-Al-Ta shape memory alloy with high martensitic transformation temperature
Wang, C. P.; Su, Y.; Y Yang, S.; Shi, Z.; Liu, X. J.
2014-02-01
In this study, a new type of Cu-Al-Ta (Cu86Al12Ta2 wt%) shape memory alloy with high martensitic transformation temperature is explored. The microstructure, reversible martensitic transformation and shape memory properties are investigated by means of optical microscopy, back-scattered electron, electron probe microanalysis, x-ray diffraction, differential scanning calorimetry and tensile tests. It is proposed that Cu86Al12Ta2 alloy consists of a mixture of primarily {\\beta }_{1}^{\\prime} martensite and a little {\\gamma }_{1}^{\\prime} martensite and some different precipitates. The tiny thin-striped Ta2(Al,Cu)3 precipitate is predominant in the as-quenched condition, whereas the particle-shaped Cu(Al, Ta) precipitate is dominant after hot-rolling. Additionally, the dendritic-shaped γ1(Cu9Al4) phase begins to appear after hot-rolling, but it disappears when the sample is re-quenched. All studied samples have reversible martensitic transformation temperatures higher than 450 ° C. The results show that two-step martensitic transformation behavior is observed for Cu86Al12Ta2 alloy in all three different conditions due to the transformations between ({\\beta }_{1}^{\\prime}+{\\gamma }_{1}^{\\prime}) martensites and the austenite parent phase. The results further show that the recovery ratios are almost 100% when the pre-strains are ≤2.5%, then they gradually decrease with further increase of the pre-strains. The shape memory effects clearly increase as a result of increase of the pre-strains, up to a maximum value of 3.2%.
2. Wetting and spontaneous infiltration: the case study of TaC/(Au, Al and Cu) compared to TiC/Cu
Aizenshtein, M.; Froumin, N.; Nafman, O.; Frage, N.
2016-06-01
Spontaneous infiltration of molten metals in to ceramic skeletons, in the course MMCs' production, is related to improved wetting of the ceramic by metals. TiC is considered a "metal-like" carbide and is supposed to be wetted well by metals through metallic bonding mechanism. Nevertheless, TiC/Cu exhibit an unusual behavior since spontaneous infiltration of molten Cu takes place, while TiC is partially wetted by Cu (θ=90°).In this work we studied the relation between wetting and spontaneous infiltration in the TaC/Au, Al and Cu systems. TaC is also considered a "metal-like" carbide and indeed no chemical interaction was observed at the interfaces of the studied systems.Sessile drop experiments showed almost perfect wetting in the three system but spontaneous infiltration occurred only in the first two (e.g. TaC/Au or Al). Thermodynamic calculation shows the difference between the systems which also has its' influence on the mechanical properties of the MMCs'. Further calculation clarifies the difference between TaC/Cu and TiC/Cu infiltration behavior, but is unable to explain the wetting results differences.Correlation between wetting and spontaneous infiltration in some cases is not straight forward and more studies and calculations on the atomistic level should be done in order to clarify this matter.
3. Transmission electron microscopy study of the failure mechanism of the diffusion barriers (TiN and TaN) between Al and Cu
Kim, Soo-Hyun
2017-01-01
Failure mechanisms of transition metal nitride thin film diffusion barriers, such as TiN and TaN (10 nm in thickness), between Al and Cu were investigated by transmission electron microscopy (TEM), scanning transmission electron microscopy, and energy dispersive spectroscopy. After annealing at 450 °C during 30 min, the TiN diffusion barrier initially failed due to an interfacial reaction between TiN and Al forming TiAl3. When the annealing temperature was increased to 500 °C, Cu-Al intermetallic compounds were formed by the interdiffusion of Al and Cu through the diffusion barrier. In the case of the Al/TaN/Cu structure, no interfacial reaction products were observed after annealing up to 550 °C. On the other hand, it failed after annealing at 550 °C due to the inter-diffusion of Cu and Al through the diffusion barrier. TEM also identified Cu to be the rapid diffusing species in both systems. The results are discussed based on the thermodynamic stability of the interface predicted by the ternary phase diagram and the diffusion kinetics of Al and Cu through the diffusion barrier. The results show that both the thermodynamic stability of the diffusion barrier between Al and Cu and the diffusion kinetics of Al and Cu through the diffusion barrier, which are dependent on the microstructure of the diffusion barrier, should be considered carefully when selecting diffusion barrier materials between Al and Cu.
4. /Cu-Al System
Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum
2014-05-01
Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.
5. Probing off-Hugoniot states in Ta, Cu, and Al to 1000 GPa compression with magnetically driven liner implosions
Lemke, R. W.; Dolan, D. H.; Dalton, D. G.; Brown, J. L.; Tomlinson, K.; Robertson, G. R.; Knudson, M. D.; Harding, E.; Mattsson, A. E.; Carpenter, J. H.; Drake, R. R.; Cochrane, K.; Blue, B. E.; Robinson, A. C.; Mattsson, T. R.
2016-01-01
We report on a new technique for obtaining off-Hugoniot pressure vs. density data for solid metals compressed to extreme pressure by a magnetically driven liner implosion on the Z-machine (Z) at Sandia National Laboratories. In our experiments, the liner comprises inner and outer metal tubes. The inner tube is composed of a sample material (e.g., Ta and Cu) whose compressed state is to be inferred. The outer tube is composed of Al and serves as the current carrying cathode. Another aluminum liner at much larger radius serves as the anode. A shaped current pulse quasi-isentropically compresses the sample as it implodes. The iterative method used to infer pressure vs. density requires two velocity measurements. Photonic Doppler velocimetry probes measure the implosion velocity of the free (inner) surface of the sample material and the explosion velocity of the anode free (outer) surface. These two velocities are used in conjunction with magnetohydrodynamic simulation and mathematical optimization to obtain the current driving the liner implosion, and to infer pressure and density in the sample through maximum compression. This new equation of state calibration technique is illustrated using a simulated experiment with a Cu sample. Monte Carlo uncertainty quantification of synthetic data establishes convergence criteria for experiments. Results are presented from experiments with Al/Ta, Al/Cu, and Al liners. Symmetric liner implosion with quasi-isentropic compression to peak pressure ˜1000 GPa is achieved in all cases. These experiments exhibit unexpectedly softer behavior above 200 GPa, which we conjecture is related to differences in the actual and modeled properties of aluminum.
6. Probing off-Hugoniot states in Ta, Cu, and Al to 1000 GPa compression with magnetically driven liner implosions
DOE PAGES
Lemke, R. W.; Dolan, D. H.; Dalton, D. G.; ...
2016-01-07
We report on a new technique for obtaining off-Hugoniot pressure vs. density data for solid metals compressed to extreme pressure by a magnetically driven liner implosion on the Z-machine (Z) at Sandia National Laboratories. In our experiments, the liner comprises inner and outer metal tubes. The inner tube is composed of a sample material (e.g., Ta and Cu) whose compressed state is to be inferred. The outer tube is composed of Al and serves as the current carrying cathode. Another aluminum liner at much larger radius serves as the anode. A shaped current pulse quasi-isentropically compresses the sample as itmore » implodes. The iterative method used to infer pressure vs. density requires two velocity measurements. Photonic Doppler velocimetry probes measure the implosion velocity of the free (inner) surface of the sample material and the explosion velocity of the anode free (outer) surface. These two velocities are used in conjunction with magnetohydrodynamic simulation and mathematical optimization to obtain the current driving the liner implosion, and to infer pressure and density in the sample through maximum compression. This new equation of state calibration technique is illustrated using a simulated experiment with a Cu sample. Monte Carlo uncertainty quantification of synthetic data establishes convergence criteria for experiments. Results are presented from experiments with Al/Ta, Al/Cu, and Al liners. Symmetric liner implosion with quasi-isentropic compression to peak pressure ~1000 GPa is achieved in all cases. Lastly, these experiments exhibit unexpectedly softer behavior above 200 GPa, which we conjecture is related to differences in the actual and modeled properties of aluminum.« less
7. Probing off-Hugoniot states in Ta, Cu, and Al to 1000 GPa compression with magnetically driven liner implosions
SciTech Connect
Lemke, R. W.; Dolan, D. H.; Dalton, D. G.; Brown, J. L.; Tomlinson, K.; Robertson, G. R.; Knudson, M. D.; Harding, E.; Mattsson, A. E.; Carpenter, J. H.; Drake, R. R.; Cochrane, K.; Blue, B. E.; Robinson, A. C.; Mattsson, T. R.
2016-01-07
We report on a new technique for obtaining off-Hugoniot pressure vs. density data for solid metals compressed to extreme pressure by a magnetically driven liner implosion on the Z-machine (Z) at Sandia National Laboratories. In our experiments, the liner comprises inner and outer metal tubes. The inner tube is composed of a sample material (e.g., Ta and Cu) whose compressed state is to be inferred. The outer tube is composed of Al and serves as the current carrying cathode. Another aluminum liner at much larger radius serves as the anode. A shaped current pulse quasi-isentropically compresses the sample as it implodes. The iterative method used to infer pressure vs. density requires two velocity measurements. Photonic Doppler velocimetry probes measure the implosion velocity of the free (inner) surface of the sample material and the explosion velocity of the anode free (outer) surface. These two velocities are used in conjunction with magnetohydrodynamic simulation and mathematical optimization to obtain the current driving the liner implosion, and to infer pressure and density in the sample through maximum compression. This new equation of state calibration technique is illustrated using a simulated experiment with a Cu sample. Monte Carlo uncertainty quantification of synthetic data establishes convergence criteria for experiments. Results are presented from experiments with Al/Ta, Al/Cu, and Al liners. Symmetric liner implosion with quasi-isentropic compression to peak pressure ~1000 GPa is achieved in all cases. Lastly, these experiments exhibit unexpectedly softer behavior above 200 GPa, which we conjecture is related to differences in the actual and modeled properties of aluminum.
8. Probing off-Hugoniot states in Ta, Cu, and Al to 10 Mbar compression with magnetically driven liner implosions
Mattsson, T. R.; Lemke, R. W.; Dolan, D. H.; Dalton, D. G.; Brown, J. L.; Robertson, G. R.; Knudson, M. D.; Harding, E.; Mattsson, A. E.; Carpenter, J. H.; Drake, R. R.; Cochrane, K.; Robinson, A. C.; Tomlinson, K.; Blue, B. E.
We report on a technique for obtaining off-Hugoniot equation of state data on solid metals by a magnetically driven cylindrical liner implosion on Sandia's Z-machine (Z). The sample material is in an inner tube with an outer tube composed of Al that serves as the current carrying cathode. A shaped current pulse quasi-isentropically compresses the sample as it implodes. Photonic Doppler velocimetry measures the implosion velocity of the free inner surface of the sample material, and the explosion velocity of the return current anode free outer surface. The velocimetry measurements are used in conjunction with magnetohydrodynamic simulations and optimization to infer pressure and density in the sample. Results are presented for experiments on the Z-machine in which Ta, Cu, and Al samples were compressed to peak pressure 10 Mbar. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
9. Mechanical and thermal behaviors of nitrogen-doped Zr-Cu-Al-Ag-Ta--An alternative class of thin film metallic glass
Chen, Pao-Sheng; Chen, Hsien-Wei; Duh, Jenq-Gong; Lee, Jyh-Wei; Shian-Ching Jang, Jason
2012-10-01
Super-plasticity and nano-scale surface roughness make thin film metallic glass (TFMG) a candidate for master mold of micro/nano imprint technique. Meanwhile, better mechanical properties of TFMG undoubtedly expand the life time of master mold. In this study, nitrogen is doped into Zr-based TFMG to exhibit the hardness higher than 10 GPa. Different from elements used to be doped into metallic glass, the role of nitrogen atoms plays in metallic glass is distinct and vital owing to its strong electronegativity. From the correlation of thermal and mechanical behavior, the role and effect of nitrogen in Ta-Zr-Cu-Al-Ag TFMG is discussed and proposed.
10. Probing off-Hugoniot states in Ta, Cu, and Al to 1000 GPa compression with magnetically driven liner implosions
SciTech Connect
Lemke, R. W. Dolan, D. H.; Dalton, D. G.; Brown, J. L.; Robertson, G. R.; Harding, E.; Mattsson, A. E.; Carpenter, J. H.; Drake, R. R.; Cochrane, K.; Robinson, A. C.; Mattsson, T. R.; Tomlinson, K.; Blue, B. E.; Knudson, M. D.
2016-01-07
We report on a new technique for obtaining off-Hugoniot pressure vs. density data for solid metals compressed to extreme pressure by a magnetically driven liner implosion on the Z-machine (Z) at Sandia National Laboratories. In our experiments, the liner comprises inner and outer metal tubes. The inner tube is composed of a sample material (e.g., Ta and Cu) whose compressed state is to be inferred. The outer tube is composed of Al and serves as the current carrying cathode. Another aluminum liner at much larger radius serves as the anode. A shaped current pulse quasi-isentropically compresses the sample as it implodes. The iterative method used to infer pressure vs. density requires two velocity measurements. Photonic Doppler velocimetry probes measure the implosion velocity of the free (inner) surface of the sample material and the explosion velocity of the anode free (outer) surface. These two velocities are used in conjunction with magnetohydrodynamic simulation and mathematical optimization to obtain the current driving the liner implosion, and to infer pressure and density in the sample through maximum compression. This new equation of state calibration technique is illustrated using a simulated experiment with a Cu sample. Monte Carlo uncertainty quantification of synthetic data establishes convergence criteria for experiments. Results are presented from experiments with Al/Ta, Al/Cu, and Al liners. Symmetric liner implosion with quasi-isentropic compression to peak pressure ∼1000 GPa is achieved in all cases. These experiments exhibit unexpectedly softer behavior above 200 GPa, which we conjecture is related to differences in the actual and modeled properties of aluminum.
11. Atomically engineering Cu/Ta interfaces.
SciTech Connect
Webb, Edmund Blackburn, III; Zhou, Xiao Wang
2007-09-01
This report summarizes the major research and development accomplishments for the late start LDRD project (investment area: Enable Predictive Simulation) entitled 'Atomically Engineering Cu/Ta Interfaces'. Two ultimate goals of the project are: (a) use atomistic simulation to explore important atomistic assembly mechanisms during growth of Cu/Ta multilayers; and (b) develop a non-continuum model that has sufficient fidelity and computational efficiency for use as a design tool. Chapters 2 and 3 are essentially two papers that address respectively these two goals. In chapter 2, molecular dynamics simulations were used to study the growth of Cu films on (010) bcc Ta and Cu{sub x}Ta{sub 1-x} alloy films on (111) fcc Cu. The results indicated that fcc crystalline Cu films with a (111) texture are always formed when Cu is grown on Ta. The Cu films are always polycrystalline even when the Ta substrate is single crystalline. These polycrystalline films are composed of grains with only two different orientations, which are separated by either orientational grain boundaries or misfit dislocations. Periodic misfit dislocations and stacking fault bands are observed. The Cu film surface roughness was found to decrease with increasing adatom energy. Due to a Cu surface segregation effect, the Cu{sub x}Ta{sub 1-x} films deposited on Cu always have a higher Cu composition than that used in the vapor mixture. When Cu and Ta compositions in the films are comparable, amorphous structures may form. The fundamental origins for all these phenomena have been studied in terms of crystallography and interatomic interactions. In chapter 3, a simplified computational method, diffusional Monte Carlo (dMC) method, was developed to address long time kinetic processes of materials. Long time kinetic processes usually involve material transport by diffusion. The corresponding microstructural evolution of materials can be analyzed by kinetic Monte Carlo simulation methods, which essentially
12. Failure mechanism of Ta diffusion barrier between Cu and Si
Laurila, Tomi; Zeng, Kejun; Kivilahti, Jorma K.; Molarius, Jyrki; Suni, Ilkka
2000-09-01
The reaction mechanisms in the Si/Ta/Cu metallization system and their relation to the microstructure of thin films are discussed on the basis of experimental results and the assessment of the ternary Si-Ta-Cu phase diagram at 700 °C. With the help of sheet resistance measurements, Rutherford backscattering spectroscopy, x-ray diffraction, a scanning electron microscope, and a transmission electron microscope, the Ta barrier layer was observed to fail at temperatures above 650 °C due to the formation of TaSi2, the diffusion of Cu through the silicide layer, and the resulting formation of Cu3Si precipitates. However, in order for the TaSi2 phase to form first, the Ta diffusion barrier layer must be thick enough (e.g., 50-100 nm) to prevent Cu diffusion into the Si substrate up to the temperature of TaSi2 formation (˜650 °C). Independent of the Ta layer thickness, Cu3Si was present as large nodules, whereas the TaSi2 existed as a uniform layer. The resulting reaction structure was found to be in local equilibrium on the basis of the assessed Si-Ta-Cu phase diagram at 700 °C, and therefore no further reactions were expected. The role of oxygen was also found to be important in the reactions and it seems to have a strong effect on the thermal stability of the barrier layer.
13. Design and fabrication of ultrathin and highly thermal-stable α-Ta/graded Ta(N)/TaN multilayer as diffusion barrier for Cu interconnects
Liu, C. H.; Wang, Y.; Liu, B.; An, Z.; Song, Z. X.; Xu, K. W.
2011-02-01
A one-step strategy of magnetron sputtering deposition with dynamic regulation of sputtering atmosphere was developed to prepare α-Ta/graded Ta(N)/TaN multilayer films on the Si substrate. The evolution of Ta clusters shows a significant effect on the crystal structure of the Ta film. The experimental results validate that the formation of α-Ta was attributed to the nucleation of larger Ta clusters. After being annealed at 600 °C, the α-Ta/graded Ta(N)/TaN multilayer film can still effectively block the diffusion of Cu. The mechanisms of the forming of the α-Ta and the thermal stability of the film stacks are characterized in detail.
14. Excellent resistive memory characteristics and switching mechanism using a Ti nanolayer at the Cu/TaOx interface
PubMed Central
2012-01-01
Excellent resistive switching memory characteristics were demonstrated for an Al/Cu/Ti/TaOx/W structure with a Ti nanolayer at the Cu/TaOx interface under low voltage operation of ± 1.5 V and a range of current compliances (CCs) from 0.1 to 500 μA. Oxygen accumulation at the Ti nanolayer and formation of a defective high-κ TaOx film were confirmed by high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photo-electron spectroscopy. The resistive switching memory characteristics of the Al/Cu/Ti/TaOx/W structure, such as HRS/LRS (approximately 104), stable switching cycle stability (>106) and multi-level operation, were improved compared with those of Al/Cu/TaOx/W devices. These results were attributed to the control of Cu migration/dissolution by the insertion of a Ti nanolayer at the Cu/TaOx interface. In contrast, CuOx formation at the Cu/TaOx interface was observed in an Al/Cu/TaOx/W structure, which hindered dissolution of the Cu filament and resulted in a small resistance ratio of approximately 10 at a CC of 500 μA. A high charge-trapping density of 6.9 × 1016 /cm2 was observed in the Al/Cu/Ti/TaOx/W structure from capacitance-voltage hysteresis characteristics, indicating the migration of Cu ions through defect sites. The switching mechanism was successfully explained for structures with and without the Ti nanolayer. By using a new approach, the nanoscale diameter of Cu filament decreased from 10.4 to 0.17 nm as the CC decreased from 500 to 0.1 μA, resulting in a large memory size of 7.6 T to 28 Pbit/sq in. Extrapolated 10-year data retention of the Ti nanolayer device was also obtained. The findings of this study will not only improve resistive switching memory performance but also aid future design of nanoscale nonvolatile memory. PMID:22734564
15. Analysis of NiAlTa precipitates in beta-NiAl + 2 at. pct Ta alloy
NASA Technical Reports Server (NTRS)
Pathare, V.; Michal, G. M.; Vedula, K.; Nathal, M. V.
1987-01-01
Results are reported from experiments performed to identify the precipitates, and their orientation in the matrix, in a beta-NiAl alloy containing 2 at. pct. Ta after undergoing creep test at 1300 K. Test specimens formed by extruding hot powders were compressed at 1300 K for about 50 hr at a strain rate averaging 6/1 million per sec. The specimens were then thinned and examined under an electron microscope and by X-ray diffractometry. An intermetallic NiAlTa compound with a hexagonal Cl4 structure appeared as second phase precipitates in the samples, exhibiting plate-like shapes and a habit plane close to (012). The prism planes of the hexagonal NiAlTa precipitates paralleled the closest packed planes in the cubic beta-NiAl matrix.
16. Diffusion barrier performance of novel Ti/TaN double layers for Cu metallization
Zhou, Y. M.; He, M. Z.; Xie, Z.
2014-10-01
Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum better than 1 × 10-3 Pa. Ti/TaN double layers were formed on SiO2/Si substrates by DC magnetron sputtering and then the properties of Cu/Ti/TaN/SiO2/Si film stacks were studied. It was found that the Ti/TaN double layers provide good diffusion barrier between Cu and SiO2/Si up to 750 °C for 30 min. The XRD, Auger and EDS results show that the Cu-Si compounds like Cu3Si were formed by Cu diffusion through Ti/TaN barrier for the 800 °C annealed samples. It seems that the improved diffusion barrier property of Cu/Ti/TaN/SiO2/Si stack is due to the diffusion of nitrogen along the grain boundaries in Ti layer, which would decrease the defects in Ti film and block the diffusion path for Cu diffusion with increasing annealing temperature. The failure mechanism of Ti/TaN bi-layer is similar to the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu3Si.
17. Diffusion barrier properties of amorphous and nanocrystalline Ta films for Cu interconnects
Cao, Z. H.; Hu, K.; Meng, X. K.
2009-12-01
In the present paper, the diffusion barrier properties of amorphous and nanocrystalline (NC) Ta films, and the interface microstructure of Ta/Cu were investigated as a function of annealing temperature. X-ray diffraction, scanning electron microscopy, cross-sectional transmission electron microscopy, and energy-dispersive spectrometer line scans were employed to study the microstructure evolution and diffusion behavior. It was found that an amorphous layer with a thickness of ˜5 nm formed at the interface of NC Ta/Cu at 450 °C annealing, while the interface of amorphous-Ta/Cu was still abrupt. Moreover, amorphous-Ta film acts as an effective diffusion barrier up to temperatures of 650 °C, which is higher than that for NC-Ta film. The fast diffusion along grain boundaries inside NC-Ta films is suggested to be responsible for the main failure of NC-Ta film.
18. Dose-enhancement effects in TaSi/Al- and Al-gate MOS devices
SciTech Connect
Fleetwood, D.M.; Beutler, D.E.; Draper, B.L.; Knott, D.; Brown, D.B.; Rosenstock, H.
1988-01-01
The response of MOS capacitors with TaSi/Al and Al electrodes to medium- and low-energy x-irradiation is investigated. Experimentally measured dose-enhancement effects are compared with computer simulations for these structures.
19. Electrodeposition of Al-Ta alloys in NaCl-KCl-AlCl3 molten salt containing TaCl5
Sato, Kazuki; Matsushima, Hisayoshi; Ueda, Mikito
2016-12-01
To form Al-Ta alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl melt containing TaCl5 at 423 K. The voltammogram showed two cathodic waves at 0.45 V and 0.7 V vs. Al/Al(III), which may correspond to reduction from Ta(V) to Ta(III) and from Ta(III) to tantalum metal, respectively. Electrodeposits of Al and Ta were obtained in the range from -0.05 to 0.3 V and the highest concentration of Ta in the electrodeposit was 72 at% at 0.3 V. With increasing Ta content in the alloy, the morphology of the electrodeposits became powdery and the particle size smaller.
20. Barrier properties and failure mechanism of Ta-Si-N thin films for Cu interconnection
Lee, Yoon-Jik; Suh, Bong-Seok; Kwon, Myoung Seok; Park, Chong-Ook
1999-02-01
Cosputtered Ta-Si-N amorphous films of ten different compositions were investigated as a barrier material for Cu interconnection. The films of relatively low nitrogen content (<47 at. %) undergo an abrupt failure with the formation of tantalum silicides and copper silicide between Si and Cu during annealing. Ta43Si4N53 thin film is readily crystallized into TaNx in spite of a remarkable chemical stability with Cu. The films containing nitrogen more than 51 at. % are sacrificial barriers which show the formation of Cu3Si phase at Ta-Si-N/Cu interface even before the films crystallize to form tantalum silicide. According to electrical tests, the barriers which show the sacrificial characteristics are most effective and show no electrical degradation even after annealing at 500 °C for an hour in Si/Cu and 525 °C for an hour in SiO2/Cu metallization.
1. Microstructural Investigations On Ni-Ta-Al Ternary Alloys
SciTech Connect
Negache, M.; Souami, N.
2010-01-05
The Ni-Al-Ta ternary alloys in the Ni-rich part present complex microstructures. They are composed of multiple phases that are formed according to the nominal composition of the alloy, primary Ni(gamma), Ni{sub 3}Al(gamma'), Ni{sub 6}AlTa(tau{sub 3}), Ni{sub 3}Ta(delta) or in equilibrium: two solid phases (gamma'-tau{sub 3}), (tau{sub 3}-delta), (tau{sub 3}-gamma), (gamma-delta) or three solid phases (gamma'-tau{sub 3}-delta). The nature and the volume fraction of these phases give these alloys very interesting properties at high temperature, and this makes them attractive for specific applications. We have developed a series of ternary alloys in electric arc furnace, determining their solidification sequences using Differential Thermal Analysis (DTA), characterized by SEM-EDS, X-ray diffraction and by a microhardness tests. The follow-up results made it possible to make a correlation between the nature of the formed phases and their solidifying way into the Ni{sub 75}Al{sub x}Ta{sub y} (x+y = 25at.%) system, which are varied and complex. In addition to the solid solution Ni (gamma), the formed intermetallics compounds (gamma', tau{sub 3} and delta) has been identified and correlated with a complex balance between phases.We noticed that the hardness increases with the tantalum which has a hardening effect and though the compound Ni{sub 3}Ta(delta) is the hardest. The below results provide a better understanding of the complex microstructure of these alloys.
2. Interatomic potential for the Cu-Ta system and its application to surface wetting and dewetting
Hashibon, Adham; Lozovoi, Alexander Y.; Mishin, Yuri; Elsässer, Christian; Gumbsch, Peter
2008-03-01
An angle-dependent interatomic potential has been developed for the Cu-Ta system by crossing two existing potentials for pure Cu and Ta. The cross-interaction functions have been fitted to first-principles data generated in this work. The potential has been extensively tested against first-principles energies not included in the fitting database and applied to molecular dynamics simulations of wetting and dewetting of Cu on Ta. We find that a Cu film placed on a Ta (110) surface dewets from it, forming a Cu droplet on top of a stable Cu monolayer. We also observe that a drop of liquid Cu placed on a clean Ta (110) surface spreads over it as a stable monolayer, while the extra Cu atoms remain in the drop. The stability of a Cu monolayer and instability of thicker Cu films are consistent with recent experiments and first-principles calculations. This agreement demonstrates the utility of the potential for atomistic simulations of Cu-Ta interfaces.
3. TaC as a diffusion barrier between Si and Cu
Laurila, Tomi; Zeng, Kejun; Kivilahti, Jorma K.; Molarius, Jyrki; Suni, Iikka
2002-04-01
The reaction mechanisms and related microstructures in the Si/TaC/Cu metallization system have been studied experimentally and theoretically by utilizing ternary Si-Ta-C and Ta-C-Cu phase diagrams as well as activity diagrams calculated at 800 °C. With the help of sheet resistance measurements, Rutherford backscattering spectrometry, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy, the metallization structure with the 70 nm thick TaC barrier layer was observed to fail completely at temperatures above 725 °C because of the formation of large Cu3Si protrusions. However, the formation of amorphous Ta layer containing significant amounts of carbon and oxygen was already observed at the TaC/Cu interface at 600 °C. This layer also constituted an additional barrier layer for Cu diffusion, which occurred only after the crystallization of the amorphous layer. The formation of Ta2O5 was observed at 725 °C with x-ray diffraction, indicating that the oxygen rich amorphous layer had started to crystallize. The formation of SiC and TaSi2 occurred almost simultaneously at 800 °C. The observed reaction structure was consistent with the thermodynamics of the ternary system. The metallization structures with 7 nm and 35 nm TaC barrier layers failed above 550 °C and 650 °C, respectively, similarly because of the formation of Cu3Si. The high formation temperature of TaSi2 and SiC implies high stability of Si/TaC interface, thus making TaC layer a potential candidate to be used as a diffusion barrier for Cu metallization.
4. Al-Cu-Zr (050)
Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.
This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-Cu-Zr (050)' with the content:
5. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys
NASA Technical Reports Server (NTRS)
Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.
1994-01-01
Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.
6. Effects of annealing on antiwear and antibacteria behaviors of TaN-Cu nanocomposite thin films
SciTech Connect
Hsieh, J. H.; Cheng, M. K.; Chang, Y. K.; Li, C.; Chang, C. L.; Liu, P. C.
2008-07-15
TaN-Cu nanocomposite films were deposited by reactive cosputtering on Si and tool steel substrates. The films were then annealed using rapid thermal annealing (RTA) at 400 deg. C for 2, 4, and 8 min, respectively, to induce the nucleation and growth of Cu particles in TaN matrix and on film surface. Field emission scanning electron microscopy was applied to characterize Cu nanoparticles emerged on the surface of TaN-Cu thin films. The effects of annealing on the antiwear and antibacterial properties of these films were studied. The results reveal that annealing by RTA can cause Cu nanoparticles to form on the TaN surface. Consequently, the tribological behaviors, as well as the antibacterial behavior may vary depending on particle size, particle distribution, and total exposed Cu amount. For the samples with large Cu particles, the reduction of averaged friction and wear rate is obvious. Apparently, it is due to the smeared Cu particles adhered onto the wear tracks. This Cu layer may act as a solid lubricant. From the antibacterial testing results, it is found that both Cu particle size and total exposed Cu amount are critical in making short-term antibacterial effect. Overall, all the annealed TaN-Cu samples can reach >99% antibacterial efficiency in 24 h, with respect to uncoated Si substrate.
7. Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys
NASA Technical Reports Server (NTRS)
Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.
1995-01-01
Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.
8. Structural Stability of Diffusion Barriers in Cu/Ru/MgO/Ta/Si
PubMed Central
Hsieh, Shu-Huei; Chen, Wen Jauh; Chien, Chu-Mo
2015-01-01
Various structures of Cu (50 nm)/Ru (2 nm)/MgO (0.5–3 nm)/Ta (2 nm)/Si were prepared by sputtering and electroplating techniques, in which the ultra-thin trilayer of Ru (2 nm)/MgO (0.5–3 nm)/Ta (2 nm) is used as the diffusion barrier against the interdiffusion between Cu film and Si substrate. The various structures of Cu/Ru/MgO/Ta/Si were characterized by four-point probes for their sheet resistances, by X-ray diffractometers for their crystal structures, by scanning electron microscopes for their surface morphologies, and by transmission electron microscopes for their cross-section and high resolution views. The results showed that the ultra-thin tri-layer of Ru (2 nm)/MgO (0.5–3 nm)/Ta (2 nm) is an effective diffusion barrier against the interdiffusion between Cu film and Si substrate. The MgO, and Ta layers as deposited are amorphous. The mechanism for the failure of the diffusion barrier is that the Ru layer first became discontinuous at a high temperature and the Ta layer sequentially become discontinuous at a higher temperature, the Cu atoms then diffuse through the MgO layer and to the substrate at the discontinuities, and the Cu3Si phases finally form. The maximum temperature at which the structures of Cu (50 nm)/Ru (2 nm)/MgO (0.5–3 nm)/Ta (2 nm)/Si are annealed and still have low sheet resistance is from 550 to 750 °C for the annealing time of 5 min and from 500 to 700 °C for the annealing time of 30 min. PMID:28347099
9. Structural Stability of Diffusion Barriers in Cu/Ru/MgO/Ta/Si.
PubMed
Hsieh, Shu-Huei; Chen, Wen Jauh; Chien, Chu-Mo
2015-11-03
Various structures of Cu (50 nm)/Ru (2 nm)/MgO (0.5-3 nm)/Ta (2 nm)/Si were prepared by sputtering and electroplating techniques, in which the ultra-thin trilayer of Ru (2 nm)/MgO (0.5-3 nm)/Ta (2 nm) is used as the diffusion barrier against the interdiffusion between Cu film and Si substrate. The various structures of Cu/Ru/MgO/Ta/Si were characterized by four-point probes for their sheet resistances, by X-ray diffractometers for their crystal structures, by scanning electron microscopes for their surface morphologies, and by transmission electron microscopes for their cross-section and high resolution views. The results showed that the ultra-thin tri-layer of Ru (2 nm)/MgO (0.5-3 nm)/Ta (2 nm) is an effective diffusion barrier against the interdiffusion between Cu film and Si substrate. The MgO, and Ta layers as deposited are amorphous. The mechanism for the failure of the diffusion barrier is that the Ru layer first became discontinuous at a high temperature and the Ta layer sequentially become discontinuous at a higher temperature, the Cu atoms then diffuse through the MgO layer and to the substrate at the discontinuities, and the Cu₃Si phases finally form. The maximum temperature at which the structures of Cu (50 nm)/Ru (2 nm)/MgO (0.5-3 nm)/Ta (2 nm)/Si are annealed and still have low sheet resistance is from 550 to 750 °C for the annealing time of 5 min and from 500 to 700 °C for the annealing time of 30 min.
10. Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions
Pstruś, Janusz; Gancarz, Tomasz
2014-05-01
The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.
11. Interface structure in Cu/Ta2O5/Pt resistance switch: a first-principles study.
PubMed
Xiao, Bo; Watanabe, Satoshi
2015-01-14
The interface structures of a Cu/Ta2O5/Pt resistance switch under various oxidation conditions have been examined from first-principles. The O-rich Cu/Ta2O5 interface is found to be stable within a wide range of O chemical potentials. In this interface structure, a considerable number of interface Cu atoms tend to migrate to the amorphous Ta2O5 (a-Ta2O5) layer, which causes the formation of the Cu2O layer. The interface Cu atoms become more ionized with an increase in the interface O concentration and/or temperature. These ionized Cu(+) ions could function as one of the main sources for the formation of conduction filaments in the Cu/a-Ta2O5/Pt resistance switch. In contrast, the ionization of the interface Cu atoms is not observed in the Cu/crystal-Ta2O5 interface primarily due to the much lower Cu ionic conductivity in crystal-Ta2O5 than that in amorphous state. In addition, the Pt electrode could not be ionized, irrespective of the interface O concentration and temperature. The formation of interface O vacancies in Pt/Ta2O5 is always energetically more stable than that in Cu/Ta2O5, which may be partly responsible for the cone shape of conduction filament formed in the Cu/a-Ta2O5/Pt resistance switch, where the base of the cone lies on the Pt/Ta2O5 interface.
12. Preparation and investigation of the quaternary alloy CuTaInSe{sub 3}
SciTech Connect
Grima-Gallardo, P. Munoz, M.; Duran, S.; Delgado, G.E.; Quintero, M.; Ruiz, J.
2007-12-04
Polycrystalline samples of the quaternary alloy CuTaInSe{sub 3} were prepared by the usual melt and anneal technique. The analysis of the diffraction pattern indicates a single phase which indexes as a tetragonal chalcopyrite-like structure with lattice parameters a = 5.7837 {+-} 0.0002 A; c = 11.6208 {+-} 0.0007 A and V = 389 {+-} 1 A{sup 3}. Differential thermal analysis shows that the melting transition of CuTaInSe{sub 3} is incongruent with large liquid + solids regions.
13. Conduction paths in Cu/amorphous-Ta{sub 2}O{sub 5}/Pt atomic switch: First-principles studies
SciTech Connect
Xiao, Bo Tada, Tomofumi; Watanabe, Satoshi; Gu, Tingkun
2014-01-21
We have examined the structure of Cu filaments in Cu/amorphous-Ta{sub 2}O{sub 5} (a-Ta{sub 2}O{sub 5})/Pt atomic switch from first principles. We have found that the Cu single atomic chains are unstable during the molecular dynamics (MD) simulation and thus cannot work as conduction paths. On the other hand, Cu nanowires with various diameters are stable and can form conductive paths. In this case, the Cu-Cu bonding mainly contributes to the conductive, delocalized defect state. These make a sharp contrast with the case of single Cu chains in crystalline Ta{sub 2}O{sub 5}, which can be conductive paths through the alternant Cu-Ta bonding structure. A series of MD simulations suggest that even Cu nanowires with a diameter of 0.24 nm can work as conduction paths. The calculations of the transport properties of Cu/a-Ta{sub 2}O{sub 5}/Pt heterostructures with Cu nanowires between two electrodes further confirm the conductive nature of the Cu nanowires in the a-Ta{sub 2}O{sub 5}.
14. Microstructure and Mechanical Properties of Bulk Nanostructured Cu-Ta Alloys Consolidated by Equal Channel Angular Extrusion
DTIC Science & Technology
2014-07-01
dynamic compression test, copper, tantalum , strength, deformation, shear punch 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18...nanocrystalline copper and tantalum [34,51–53,56,57]. Property Symbol Cu–1Ta 700 C Cu–10Ta 900 C Cu–10Ta 700 C NC pure Cu NC pure Ta HV 2.12 2.12 3.75 2.55
15. Mechanical properties of Cu/Ta multilayers prepared by magnetron sputtering
SciTech Connect
Nguyen, T.D.; Barbee, T.W., Jr.
1998-04-01
The microstructure and mechanical properties of sputtered Cu/Ta multilayers were studied. X- ray diffraction and transmission electron microscopy characterization indicate that both the Ta and Cu in the 2 nm period multilayer are predominantly amorphous, while in longer period samples, the layers are crystalline, with the metastable tetragonal {beta}-Ta observed. No observable microstructure changes upon annealing at 300{degrees}C were found. An average Vickers micro- hardness value of about 5.5 GPa was measured, which increases about 5% upon annealing at 300{degrees}C. Residual stress in the multilayers and its dependence on thermal annealing are reported. The relationships between microstructure and mechanical properties in the multilayers are discussed.
16. Sputtered Ta-Si-N diffusion barriers in Cu metallizations for Si
NASA Technical Reports Server (NTRS)
Kolawa, E.; Pokela, P. J.; Reid, J. S.; Chen, J. S.; Nicolet, Marc A.; Ruiz, R. P.
1991-01-01
Electrical measurements on shallow Si n+-p junction diodes with a 30-nm TiSi2 contacting layer demonstrate that an 80-nm-thick amorphous Ta36Si14N50 film prepared by reactive RF sputtering of a Ta5Si3 target in an Ar/N2 plasma very effectively prevents the interaction between the Si substrate with the TiSi2 contacting layer and a 500-nm Cu overlayer. The Ta36Si14N50 diffusion barrier maintains the integrity of the I-V characteristics up to 900 C for 30-min annealing in vacuum. It is concluded that the amorphous Ta36Si14N50 alloy is not only a material with a very low reactivity for copper, titanium, and silicon, but must have a small diffusivity for copper as well.
17. High Nb, Ta, and Al creep- and oxidation-resistant austenitic stainless steel
DOEpatents
Brady, Michael P [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Yamamoto, Yukinori [Oak Ridge, TN; Liu, Chain-tsuan [Oak Ridge, TN
2010-07-13
An austenitic stainless steel HTUPS alloy includes, in weight percent: 15 to 30 Ni; 10 to 15 Cr; 2 to 5 Al; 0.6 to 5 total of at least one of Nb and Ta; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1 W; up to 0.5 Cu; up to 4 Mn; up to 1 Si; 0.05 to 0.15 C; up to 0.15 B; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni wherein said alloy forms an external continuous scale comprising alumina, nanometer scale sized particles distributed throughout the microstructure, said particles comprising at least one composition selected from the group consisting of NbC and TaC, and a stable essentially single phase fcc austenitic matrix microstructure, said austenitic matrix being essentially delta-ferrite-free and essentially BCC-phase-free.
18. Pulsed laser deposition growth of heteroepitaxial YBa2Cu3O7/La0.67Ca0.33MnO3 superlattices on NdGaO3 and Sr0.7La0.3Al0.65Ta0.35O3 substrates
Malik, V. K.; Marozau, I.; Das, S.; Doggett, B.; Satapathy, D. K.; Uribe-Laverde, M. A.; Biskup, N.; Varela, M.; Schneider, C. W.; Marcelot, C.; Stahn, J.; Bernhard, C.
2012-02-01
Heteroepitaxial superlattices of [YBa2Cu3O7(n)/La0.67Ca0.33MnO3(m)]x (YBCO/LCMO), where n and m are the number of YBCO and LCMO monolayers and x the number of bilayer repetitions, have been grown with pulsed laser deposition on NdGaO3 (110) and Sr0.7La0.3Al0.65Ta0.35O3 (001). These substrates are well lattice matched with YBCO and LCMO and, unlike the commonly used SrTiO3, they do not give rise to complex and uncontrolled strain effects at low temperature. The growth dynamics and the structure have been studied in situ with reflection high-energy electron diffraction and ex situ with scanning transmission electron microscopy, x-ray diffraction, and neutron reflectometry. The individual layers are found to be flat and continuous over long lateral distances with sharp and coherent interfaces and with a well-defined thickness of the individual layer. The only visible defects are antiphase boundaries in the YBCO layers that originate from perovskite unit-cell height steps at the interfaces with the LCMO layers. We also find that the first YBCO monolayer at the interface with LCMO has an unusual growth dynamics and is lacking the CuO chain layer, while the subsequent YBCO layers have the regular Y-123 structure. Accordingly, the CuO2 bilayers at both the LCMO/YBCO and the YBCO/LCMO interfaces are lacking one of their neighboring CuO chain layers and, thus, half of their hole-doping reservoir. Nevertheless, from electric transport measurements on a superlattice with n=2 we obtain evidence that the interfacial CuO2 bilayers remain conducting and even exhibit the onset of a superconducting transition at very low temperature. Finally, we show from dc magnetization and neutron reflectometry measurements that the LCMO layers are strongly ferromagnetic.
19. Study on quasiperiodic Ta/Al multilayer films by x-ray diffraction
SciTech Connect
Peng, R.W.; Hu, A.; Jiang, S.S. )
1991-11-11
Quasiperiodic (Fibonacci) Ta/Al multilayer films with Ta(110) and Al(111) textures were fabricated by magnetron sputtering. The structure of the multilayers was characterized in detail by x-ray diffraction. The diffraction peaks at low and high angles can be indexed by the projection method from the high-dimension periodic structure. The experimental results were in good agreement with the numerical calculation using the model for the compositionally modulated multilayers. The diffraction spectrum of the quasiperiodic Ta/Al multilayers is totally different from that of periodic structure, and the possible application of Fibonacci films as optical elements in a soft x-ray region is discussed.
20. Thermal and structural stability of cosputtered amorphous Ta(x)Cu(1-x) alloy thin films on GaAs
NASA Technical Reports Server (NTRS)
Oh, J. E.; Woolam, J. A.; Aylesworth, K. D.; Sellmyer, D. J.; Pouch, J. J.
1986-01-01
The characteristics of thin films of Ta-Cu, prepared over a wide range of compositions by cosputter deposition onto GaAs and fused quartz substrates, are studied by X-ray diffraction and van der Pauw resistivity measurement. Results show films to be amorphous over the range of 55-95 at. pct, and show Ta(93)Cu(7) barriers to be effective in preventing Au in-diffusion, with a 3000-A layer remaining unpenetrated after an annealing at 700 C for 20 min. Diffusion of Ga and/or As into amorphous 93 at. pct Ta is found to be more rapid than that of Au, and interfacial reactions were shown to form compounds including Ta3Au, CuAu, TaAs2, and Ga3Cu7 above 700 C.
1. Prediction of novel alloy phases of Al with Sc or Ta
PubMed Central
Bilić, Ante; Gale, Julian D.; Gibson, Mark A.; Wilson, Nick; McGregor, Kathie
2015-01-01
Using the evolutionary optimization algorithm, as implemented in the USPEX crystal predictor program, and first principles total energy calculations, the compositional phase diagrams for Al-Sc and Al-Ta alloy systems at zero temperature and pressure have been calculated. In addition to the known binary intermetallic phases, new potentially stable alloys, AlSc3 and AlTa7, have been identified in the Al-poor region of the phase diagram. The dynamic and thermal stability of their lattices has been confirmed from the calculated vibrational normal mode spectra in the harmonic approximation. PMID:25950915
2. Study of Dissolution Process of Solid Cu in Liquid Al
Chen, Shuying; Wu, Yang; Chang, Guowei; Zhu, Changxu; Li, Qingchun
2016-09-01
The dissolution process of solid Cu in liquid Al influences the compound quality directly when fabricating the copper cladding aluminum (CCA) composite castings utilizing the casting aluminum method. Dissolution rate of solid Cu is investigated utilizing the method of quenching rapidly. Effects of liquid Al temperature and the contact time between solid Cu and liquid Al on the dissolution rate of Cu are investigated; meanwhile, the dissolution mechanism of Cu is explored. Subsequently, the influences of processing parameters on the dissolution thickness of Cu are examined. The results indicate that chemical compounds, such as AlCu2, Cu5Al, CuAl2 and Cu2Al3, may form on the contact surface between solid Cu and liquid Al. These chemical compounds are contributed to decompose the solid Cu, Cu5Al exerts the greatest effect. The dissolution of Cu is affected by the contact time between solid Cu and liquid Al, temperature and cooling method of Cu plate. The dissolution of Cu cannot terminate immediately even though the Cu plate is cooled by the spray. The experimental results will provide a reference for controlling the composite layer thickness.
3. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems
NASA Technical Reports Server (NTRS)
Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.
1995-01-01
Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.
4. Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles
PubMed Central
Abedini, Alam; Saion, Elias; Larki, Farhad; Zakaria, Azmi; Noroozi, Monir; Soltani, Nayereh
2012-01-01
Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. PMID:23109893
5. Development of Ta-matrix Nb3Al Strand and Cable for High-Field Accelerator Magnet
SciTech Connect
Tsuchiya, K.; Ghosh, A.; Kikuchi, A.; Takeuchi, T.; Banno, N.; Iijima, Y.; Nimori, S.; Takigawa, H.; Terashima, A.; Nakamoto, T.; Kuroda, Y.; Maruyama, M.; Takao, T.; Tanaka, K.; Nakagawa, K.; Barzi, E.; Yamada, R.; Zlobin, A.
2011-08-03
Research and development of Nb{sub 3}Al strands and cables for a high field accelerator magnet is ongoing under the framework of the CERN-KEK collaboration. In this program, new Ta-matrix Nb{sub 3}Al strands were developed and their mechanical properties and superconducting properties were studied. The non-Cu J{sub c} values of these strands were 750 {approx} 800 A/mm{sup 2} at 15 T and 4.2 K. Using these strands, test fabrication of 27-strand Rutherford cable was carried out in collaboration with NIMS and Fermilab. The properties of the strands extracted from the cable were examined and it was found that there was no degradation of the superconducting properties of the strands. In this paper, we report the fabrication of the strands and the cable in brief and present some of the results obtained by studying their properties.
6. Structure and Microhardness of Cu-Ta Joints Produced by Explosive Welding
PubMed Central
Maliutina, Iu. N.; Mali, V. I.; Bataev, I. A.; Bataev, A. A.; Esikov, M. A.; Smirnov, A. I.; Skorokhod, K. A.
2013-01-01
The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20⋯40 μm thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5⋯500 nm, with a predominance of 5⋯50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV) and tantalum (~160 HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818
7. Islamic Education Philosophy Development (Study Analysis on Ta'lim Al-Kitab Al-Zarnuji Muta'allim Works)
ERIC Educational Resources Information Center
2016-01-01
"Ta'lim Muta'allim" is one of the monumental works of Shaykh Tajuddin Nu'man ibn Ibrahim ibn al-Khalil al-Zarnuji, who lived in the 6th century H/13-14 M. The reason for writing this study ie: (1) it is very rich with the basic values of Islamic education, (2) the values are already widely practiced in the world of education, especially…
8. Growth and Oxidation of Thin Film Al(2)Cu
SciTech Connect
SON,KYUNG-AH; MISSERT,NANCY A.; BARBOUR,J. CHARLES; HREN,J.J.; COPELAND,ROBERT GUILD; MINOR,KENNETH G.
2000-01-18
Al{sub 2}Cu thin films ({approx} 382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {micro} 3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30-70 {micro}m wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67 {+-} 2% Al and 33 {+-} 2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approx} 5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.
9. Electrochemical characterization of surface complexes formed on Cu and Ta in succinic acid based solutions used for chemical mechanical planarization
Sulyma, Christopher M.; Roy, Dipankar
2010-02-01
Open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu lines and Ta barriers in the fabrication of semiconductor devices. It is shown that in non-alkaline solutions of H 2O 2, the SA-promoted surface complexes of Cu and Ta can potentially support chemically enhanced material removal in low-pressure CMP of surface topographies overlying fragile low-k dielectrics. ADS can suppress Cu dissolution without significantly affecting the surface chemistry of Ta. The data analysis steps are discussed in detail to demonstrate how the D.C. and A.C. electrochemical probes can be combined in the framework of the RDE technique to design and test CMP slurry solutions.
10. Properties of TaN{sub {ital x}} films as diffusion barriers in the thermally stable Cu/Si contact systems
SciTech Connect
Takeyama, M.; Noya, A.; Sase, T.; Ohta, A.; Sasaki, K.
1996-03-01
The properties of Ta{sub 2}N and TaN compound films as a diffusion barrier between Cu and Si have been investigated by examining compositional depth profiles obtained by Auger electron spectroscopy. The use of a Ta{sub 2}N barrier is effective for improving the thermal stability of the contact system by raising the silicide formation temperature as compared with the use of a Ta barrier. The contact system of Cu/TaN/Si is fairly stable due to annealing for 1 h even at 750{degree}C. This is interpreted by the stability of the TaN compound, which is chemically inert to Si as well as Cu at this temperature. Eliminating the grain growth of TaN due to annealing is also effective for suppressing the physical diffusion through the barrier. {copyright} {ital 1996 American Vacuum Society}
11. Isothermal oxidation behavior and microstructure of plasma surface Ta coating on γ-TiAl
SciTech Connect
Song, Jian; Zhang, Ping-Ze Wei, Dong-Bo; Wei, Xiang-Fei; Wang, Ya
2014-12-15
The oxidation behavior of γ-TiAl with Ta surface coating fabricated by double glow plasma surface alloying technology was investigated by thermogravimetric method. Oxidation experiments were carried out at 750 °C and 850 °C in air for 100 h. The modification layer was comprised of deposition layer and diffusion layer, which metallurgically adhered to the substrate. Tantalum element decreased with the case depth. The oxidation morphology was studied by a scanning electron microscope and X-ray diffraction. The results highlighted that in the oxidizing process of the oxidation, the phase containing Ta-richer may restrain diffusing outward of the element Al in the matrix. Ti diffused outward, and formed the TiO{sub 2} scales, while the middle layer was rich in Al, and formed the continuous Al{sub 2}O{sub 3} scales after oxidation, which was effective to prevent further infiltration of oxygen atoms, and as a result the oxidation resistance increased immensely. - Highlights: • A Ta modified coating was prepared on γ-TiAl using DGP surface alloying technology. • The modification layer metallurgically adhered to the substrate. • The bonding force is about 60 N, satisfying the demands of practical use. • The oxidation resistance increased immensely at 750 °C and 850 °C.
12. Fluoride (F) is not taken up by Salmonella typhimurium TA98 (TA98), used for Ames mutagenicity test, unless aluminum (Al) is present
SciTech Connect
Ahn, H.W.; Jeffery, E.H. )
1991-03-11
TA98 is commonly used for the Ames test to detect frame-shift mutations. Ames test results for fluoride mutagenicity are controversial. Since Al and F, both present in finished drinking water, form a stable complex, the authors determined the effect of Al on F uptake by TA98 to evaluate any Al effect on Ames test results for F. A known number of TA98 in 0.1M potassium phosphate buffer was incubated with various concentrations of Al, F or aluminum fluoride for 1 hr at 37C in a shaking incubator. The cells were washed twice in potassium phosphate buffer and then resuspended in water. After breaking the cells open by sonication, the resulting supernatant was analyzed for Al by graphite furnace atomic absorption and for F using a F ion-selective electrode. Al accumulated in a concentration-dependent manner to 4.5 ppm then decreased rapidly as the Al was increased to 9 ppm. Intracellular F was below the limit of detection even when the medium contained 590 ppm F. However, F was taken up from media containing greater than 200 ppm F, providing that aluminum was also present. The authors conclude that the Ames test, using TA98, is not suitable for the detection of F mutagenicity.
13. Structure of the copper(I) tantalum oxide, Cu/sub 5/Ta/sub 11/O/sub 30/
SciTech Connect
Jahnberg, L.
1982-03-01
The structure of hexagonal CU/sub 6/Ta/sub 11/O/sub 30/ (space group P62c) has been determined from single-crystal diffractometer data. The cell dimensions are a = 6.2297(2) angstrom and c = 32,550(2) angstrom, and the cell content is two formula units. The structure is related to those of CaTa/sub 4/O/sub 11/ and CeTa/sub 7/O/sub 19/ and contains alternately single and double layers of TaO/sub 7/ pentagonal bipyramids sharing edges in the equatorial plane in the same way as UO/sub 7/ in ..cap alpha..-U/sub 3/O/sub 8/. The layers are connected by TaO/sub 6/ octahedra and linear CuO/sub 2/ groups, both formed by the apex oxygens of the TaO/sub 7/ bipyramids. Refinement was made with the least-squares technique using 729 reflections, of which 422 were independent. The conventional R value was 3.9%.
14. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression.
PubMed
Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro
2016-08-13
15. Novel high-strength NiCuCoTiTa alloy with plasticity
Samal, Sumanta; Biswas, Krishanu
2013-07-01
The present investigation reports a novel Ni-Ti-based Ni48Cu10Co2Ti38Ta2 alloy, obtained by arc melting cum suction casting route under ultrahigh-purity Ar atmosphere. X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy (TEM) investigations reveal a microstructure consisting of nanostructured eutectic between cubic NiTi and hexagonal Ni3Ti with micron-scale NiTi and cubic Ti2Ni dendrites. Detailed TEM investigation indicates substantial reduction in the interlamellar spacing as the alloy chemistry changes from binary to quinary. The alloy shows a high compressive strength, 2 GPa, with high plasticity 13 %. Fractography surface of this new alloy reveals mixed mode of fracture. The results are discussed in light of the available literature on deformation of nanostructured eutectic with micron-sized dendrites in the microstructures.
16. Mechanical Failure of Thin Ta and Cu/Ta Layers on Polyimide Substrates: A Synchrotron-Based Technique for In Situ Characterization
SciTech Connect
Frank, Stephan; Olliges, Sven; Spolenak, Ralph; Handge, Ulrich A.
2009-06-18
In situ synchrotron radiation diffraction and confocal light microscopy is used to study fragmentation and buckling of thin brittle Ta layers with thicknesses of 50 nm, 100 nm and 200 nm on polyimide substrates. Synchrotron-based stress measurements confirm that cracking leads to relaxation of tensile stress. Simultaneously, compressive stress arises in transverse direction, which finally leads to buckling. This behavior can be explained quantitatively by a two-dimensional shear lag model. It is well established that the properties of the coating-substrate interface determine the processes of coating fragmentation and delamination. A possible approach for influencing and controlling these processes is given by the incorporation of a ductile interlayer. It can be observed that the presence of Cu interlayers with thicknesses of 5 nm, 20 nm and 50 nm reduces the fracture strength of brittle Ta coatings on polyimide substrates, whereas the resistance to buckling is increased significantly.
17. Intermetallic Phase Formation in Explosively Welded Al/Cu Bimetals
Amani, H.; Soltanieh, M.
2016-08-01
Diffusion couples of aluminum and copper were fabricated by explosive welding process. The interface evolution caused by annealing at different temperatures and time durations was investigated by means of optical microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, and x-ray diffraction. Annealing in the temperature range of 573 K to 773 K (300 °C to 500 °C) up to 408 hours showed that four types of intermetallic layers have been formed at the interface, namely Al2Cu, AlCu, Al3Cu4, and Al4Cu9. Moreover, it was observed that iron trace in aluminum caused the formation of Fe-bearing intermetallics in Al, which is near the interface of the Al-Cu intermetallic layers. Finally, the activation energies for the growth of Al2Cu, AlCu + Al3Cu4, Al4Cu9, and the total intermetallic layer were calculated to be about 83.3, 112.8, 121.6, and 109.4 kJ/mol, respectively. Considering common welding methods ( i.e., explosive welding, cold rolling, and friction welding), although there is a great difference in welding mechanism, it is found that the total activation energy is approximately the same.
18. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution
Wang, Ying; Liang, Shuhua; Yang, Qing; Wang, Xianhui
2016-11-01
Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl2 + HCl solution. Compared to Cu40Al60 and Cu45Al55 alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu17Al83 alloy as the starting alloy. The growth direction of the FDC is <110>, and all angles between the trunks and branches are 60°. Nanoscale Cu2O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu17Al83 alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl2 intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.
19. Intermetallic compound formation at Cu-Al wire bond interface
Bae, In-Tae; Young Jung, Dae; Chen, William T.; Du, Yong
2012-12-01
Intermetallic compound (IMC) formation and evolution at Cu-Al wire bond interface were studied using focused ion beam /scanning electron microscopy, transmission electron microscopy (TEM)/energy dispersive x-ray spectroscopy (EDS), nano beam electron diffraction (NBED) and structure factor (SF) calculation. It was found that discrete IMC patches were formed at the Cu/Al interface in as-packaged state and they grew toward Al pad after high temperature storage (HTS) environment at 150 °C. TEM/EDS and NBED results combined with SF calculation revealed the evidence of metastable θ'-CuAl2 IMC phase (tetragonal, space group: I4¯m2, a = 0.404 nm, c = 0.580 nm) formed at Cu/Al interfaces in both of the as-packaged and the post-HTS samples. Two feasible mechanisms for the formation of the metastable θ'-CuAl2 phase are discussed based on (1) non-equilibrium cooling of wire bond that is attributed to highly short bonding process time and (2) the epitaxial relationships between Cu and θ'-CuAl2, which can minimize lattice mismatch for θ'-CuAl2 to grow on Cu.
20. Effect of Cu Addition to Zn-12Al Alloy on Thermal Properties and Wettability on Cu and Al Substrates
Gancarz, Tomasz; Pstruś, Janusz; Mosińska, Sylwia; Pawlak, Sylwia
2016-01-01
The thermal properties, electrical resistivity, thermal linear expansion and tensile strength of a new high-temperature lead-free solder based on a eutectic Zn-Al alloy with 0.5, 1.0, or 1.5 at. pct Cu added were studied. Wettability studies on Cu substrate were performed with flux at 773 K (500 °C) for 60, 180, 240, 900, 1800, and 3600 seconds, and for 480 seconds at 733 K, 753 K, 773 K, 793 K, and 823 K (460 °C, 480 °C, 500 °C, 520 °C, and 550 °C, respectively). The experiment was designed to demonstrate the effect of the addition of Cu on the kinetics of the formation and growth of the CuZn, Cu5Zn8, CuZn4, and Al4Cu9 phases, which were identified by X-ray diffraction analysis. Wetting tests were also performed on the Al substrate, for 15 and 30 seconds at 773 K and 793 K (500 °C and 520 °C, respectively). Very low contact angles on Al pads were obtained. The electrical resistivity of Zn-Al-Cu alloys was slightly higher than that of the ZnAl eutectic alloy. The present results are discussed with respect to the available literature on Zn-Al and Zn-Al-Cu alloys.
1. Modelling potential photovoltaic absorbers Cu3MCh4(M = V, Nb, Ta; Ch = S, Se, Te) using density functional theory.
PubMed
Kehoe, Aoife B; Scanlon, David O; Watson, Graeme W
2016-05-05
The geometric and electronic properties of a series of potential photovoltaic materials, the sulvanite structured Cu3MCh4(M = V, Nb, Ta; Ch = S, Se, Te), have been computationally examined using both PBEsol+U and HSE06 methods to assess the materials' suitability for solar cell application and to compare the predictions of the two theoretical approaches. The lattice parameters, electronic density of states, and band gaps of the compounds have been calculated to ascertain the experimental agreement obtained by each method and to determine if any of the systems have an optical band gap appropriate for photovoltaic absorber materials. The PBEsol+U results are shown to achieve better agreement with experiment than HSE06 in terms of both lattice constants and band gaps, demonstrating that higher level theoretical methods do not automatically result in a greater level of accuracy than their computationally less expensive counterparts. The PBEsol+U calculated optical band gaps of five materials suggest potential suitability as photovoltaic absorbers, with values of 1.72 eV, 1.49 eV, 1.19 eV, 1.46 eV, and 1.69 eV for Cu3VS4, Cu3VSe4, Cu3VTe4, Cu3NbTe4, and Cu3TaTe4, respectively, although it should be noted that all fundamental band gaps are indirect in nature, which could lower the open-circuit voltage and hence the efficiency of prospective devices.
2. Oxidation characteristics of Ti-33Al-6Nb-1.4Ta
NASA Technical Reports Server (NTRS)
Wallace, T. A.; Clark, R. K.; Sankaran, S. N.; Wiedemann, K. E.
1991-01-01
Static oxidation kinetics of the gamma titanium-aluminide alloy Ti-33Al-6Nb-1.4Ta (wt pct) have been investigated in air from 700 to 1000 C and in oxygen from 800 to 1000 C using thermogravimetric analysis. The oxidation kinetics were controlled by the presence of alumina for all oxygen exposures and in air below 800 C, while the kinetics in air above 800 C were more complex. Oxidation products were identified using X-ray diffraction techniques. Oxide scale morphology was examined by SEM and TEM of the surfaces and across sections of oxidized specimens. The oxidation products formed depended on the exposure: Al2O3 and TiO2 were identified on all specimens exposed in and air and oxygen; the nitride phases TiN and Ti2AlN were also found on specimens exposed in air.
3. Al-to-Cu Friction Stir Lap Welding
Firouzdor, Vahid; Kou, Sindo
2012-01-01
Recently, friction stir welding (FSW) has been used frequently to join dissimilar metals, for instance, Al to Mg, Cu, and steel. The formation of brittle intermetallic compounds often severely limits the strength and ductility of the resultant welds. In the present study, Al-to-Cu lap FSW was studied by welding 6061 Al to commercially pure Cu. Conventional lap FSW was modified by butt welding a small piece of Al to the top of Cu, with a slight pin penetration into the bottom of Al. At travel speeds up to 127 mm/min (5 ipm), the modified welds were about twice the joint strength and five to nine times the ductility of the conventional lap welds. In the conventional lap welds, voids were present along the Al-Cu interface, and fracture occurred along the interface in tensile testing. No such voids were observed in the modified lap welds, and fracture occurred through Cu. Thus, as in the case of Al-to-Mg lap FSW recently studied by the authors, modified lap FSW significantly improved the weld quality in Al-to-Cu lap FSW. At the relatively high travel speed of 203 mm/min (8 ipm), however, modified lap FSW was no longer superior because of channel formation.
4. Perpendicular magnetic anisotropy in Ta/Co2FeAl/MgO multilayers
Gabor, M. S.; Petrisor, T.; Tiusan, C.; Petrisor, T.
2013-08-01
In this paper, we demonstrate the stabilization of perpendicular magnetic anisotropy (PMA) in Ta/Co2FeAl/MgO multilayers sputtered on thermally oxidized Si(100) substrates. The magnetic analysis points out that these films show significant interfacial anisotropy even in the as-deposited state, KS=0.67 erg/cm2, enough to provide PMA for the as-deposited films with thicknesses below 1.5 nm. Moreover, the interfacial anisotropy is enhanced by thermal annealing up to 300 °C. The presence of a magnetic dead layer, whose thickness increases with annealing temperature, was also identified.
NASA Technical Reports Server (NTRS)
Regan, T. M.; Stoloff, N. S.
1977-01-01
The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.
6. Influence of Al content on non-equilibrium solidification behavior of Ni-Al-Ta model single crystal alloys
Ai, Cheng; Zhou, Jian; Zhang, Heng; Zhao, Xinbao; Pei, Yanling; Li, Shusuo; Gong, Shengkai
2016-01-01
The non-equilibrium solidification behaviors of five Ni-Al-Ta ternary model single crystal alloys with different Al contents were investigated by experimental analysis and theoretical calculation (by JMatPro) in this study. These model alloys respectively represented the γ' phase with various volume fractions (100%, 75%, 50%, 25% and 0%) at 900 °C. It was found that with decreasing Al content, liquidus temperature of experimental alloys first decreased and then increased. Meanwhile, the solidification range showed a continued downward trend. In addition, with decreasing Al content, the primary phases of non-equilibrium solidified model alloys gradually transformed from γ' phase to γ phase, and the area fraction of which first decreased and then increased. Moreover, the interdendritic/intercellular precipitation of model alloys changed from β phase (for 100% γ') to (γ+γ')Eutectic (for 75% γ'), (γ+γ')Eutectic+γ' (for 50% γ' and 25% γ') and none interdendritic precipitation (for 0% γ'), and the last stage non-equilibrium solidification sequence of model alloys was determined by the nominal Al content and different microsegregation behaviors of Al element.
7. An impedance study of complex Al/Cu-Al2O3 electrode
Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.
2011-06-01
Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.
8. Controlling microstructure, preferred orientation, and mechanical properties of Cr-Al-N by bombardment and alloying with Ta
Hollerweger, R.; Zhou, L.; Holec, D.; Koller, C. M.; Rachbauer, R.; Polcik, P.; Mayrhofer, P. H.
2016-02-01
Recent ab initio studies showed that the inherent ductility of cubic structured Cr1-xAlxN coatings (as compared with similar hard coatings) significantly increases when alloyed with Ta. As there is only little experimental and theoretical information available, we have performed a combined experimental and ab initio based study on the influence of Ta additions (0, 2, 6, 12, and 26 at. % on the metal sublattice) on structure and mechanical properties of arc evaporated Cr1-x-yAlxTayN coatings with Al/(Cr + Al) ratios >0.61. With increasing Ta-content, the droplet number density decreases and the coating surface smoothens, which is much more pronounced as with increasing the bias potential from -40 to -120 V. Simultaneously, the columnar structure observed for Ta-free Cr0.37Al0.63N significantly changes into a fine-grained structure (crystallite size ˜5 nm) with clearly reduced columnar character. Increasing the Ta content also favors the formation of a preferred 200 growth orientation resulting in a reduction of the indentation moduli E from ˜500 to ˜375 GPa, which is in agreement with ab initio calculations. As the hardness H remains between 34 and 41 GPa, an increased resistance against brittle fracture is indicated with increasing Ta.
9. Chemical-mechanical planarization of Al and Cu thin films for the damascene process
Wrschka, Peter Thomas
In this thesis, the chemical-mechanical planarization (CMP) of Al and Cu thin films is investigated. Our results are obtained by polishing blanket and patterned wafers covered with either Al or Cu utilizing various pads and slurries. Removal rates and metal to SiO2 selectivity values at different pressures and velocities are measured. Furthermore, the results of the successful planarization of Al and Cu damascene structures are reported here. We analyze the surface oxidation of Al before and immediately after the polishing of blanket wafers by X-ray photoelectron spectroscopy. The results show that the CMP of Al proceeds by the growth and removal of the metal passivation layer, i.e. Al2O3. A model for the Al removal mechanism is proposed, which states that the in-situ passivation layer thickness is inversely proportional to the removal rate. The CMP of Cu damascene structures found that the Cu line recess, metal line corrosion and the adherence of slurry particles is determined by the slurry formulation. Cu line dishing, comer rounding of the SiO2 spacer and the pattern density dependence of the removal rate is controlled by the type of pad utilized. We found that moderate etch rates (~10 nm/min) yield high removal rates (~1 μm/min) and low Cu line recess (<10% of Cu line thickness). The occurrence of corrosion is favored at small feature sizes in low pattern density areas. However, this can be avoided by employing passivating agents. The dishing of metal lines and the comer rounding of dielectric spacers is prevented by employing a sufficiently hard pad. The diffusion barrier layer removal (Ta), which shows no chemical etching in the slurry, is affected by the pad and the slurry particle type. A hard pad and especially the use of silica particles enhances the liner removal significantly. Silica particles also adhere less to the metal lines and settle at a substantially slower rate in the slurry than alumina particles.
10. Composition dependence of the electronic properties of Al-Cu-Fe and Al-Cu-Ru-Si semimetallic quasicrystals
Pierce, F. S.; Bancel, P. A.; Biggs, B. D.; Guo, Q.; Poon, S. J.
1993-03-01
Electronic transport properties and specific heats of ordered icosahedral phase alloys in the Al-Cu-Ru-Si and Al-Cu-Fe systems are examined, and comparison with high-quality rhombohedral (3/2) approximant phase samples of Al-Cu-Fe is made. Strong temperature dependence and sensitivity to composition changes of these properties are observed. The similarity of transport properties between the icosahedral (i) and rhombohedral (r) phases of Al62.5Cu26.5Fe11 is noted. The results can be qualitatively interpreted in terms of band structure. There appears to be sufficient evidence for a rapidly varying conductivity spectrum σ(E) in the ordered i phases. However, important questions concerning the physics of these semimetallic quasicrystals remain to be answered.
11. Processing, physical metallurgy and creep of NiAl + Ta and NiAl + Nb alloys. Ph.D. Thesis. Final Contractor Report
NASA Technical Reports Server (NTRS)
Pathare, Viren M.
1988-01-01
Powder processed NiAl + Ta alloys containing 1, 2, and 4.5 at percent tantalum and NiAl + Nb alloys containing 1 and 2 at percent niobium were developed for improved creep properties. In addition, a cast alloy with 5 at percent tantalum was also studied. Hot extrusion parameters for processing alloys with 1 and 2 at percent of tantalum or niobium were designed. The NiAl + 4.5 at percent Ta alloy could be vacuum hot pressed successfully, even though it could not be extruded. All the phases in the multiphase alloys were identified and the phase transformations studied. The Ni2AlTa in NiAl + 4.5 at percent Ta alloy transforms into a liquid phase above 1700 K. Solutionizing and annealing below this temperature gives rise to a uniform distribution of fine second phase precipitates. Compressive creep properties were evaluated at 1300 K using constant load and constant velocity tests. In the higher strain rate region single phase NiAl + 1 at percent Ta and NiAl + 1 at percent Nb alloys exhibit a stress exponent of 5 characteristic of climb controlled dislocation creep. In slower strain rate regime diffusional creep becomes important. The two phase alloys containing 2 to 5 at percent Ta and 2 at percent Nb show considerable improvement over binary NiAl and single phase alloys. Loose dislocation networks and tangles stabilized by the precipitates were found in the as crept microstructure. The cast alloy which has larger grains and a distribution of fine precipitates shows the maximum improvement over binary NiAl.
12. Kinetic parameters and structural variations in Cu-Al-Mn and Cu-Al-Mn-Mg shape memory alloys
Canbay, Canan Aksu
2017-02-01
In this work polycrystalline Cu-Al-Mn and Cu-Al-Mn-Mg SMAs were fabricated by arc melting. The thermal analysis was made to determine the characteristic transformation temperatures of the samples and kinetic parameters. Also the effect of Mg on transformation temperatures and kinetic parameters detected. The structural analysis was made to designate the diffraction planes of martensite phase at room temperature and this was supported by optical measurement observations.
13. A first-principles study of the tetragonal and hexagonal R 2Al (R = Cr, Zr, Nb, Hf, Ta) phases
Shang, Xiu; Shen, Jiang; Tian, Fuyang
2016-10-01
The crystal structures, elastic moduli, electronic structure, and phonon dispersion of the tetragonal R 2Al (R = Cr, Zr, Nb, Hf, Ta) intermetallic compounds are investigated by using the first-principles method. The space group number is 139 for tetragonal Cr2Al, 136 for tetragonal Nb2Al and Ta2Al, and the space group numbers are 140 and 194 for tetragonal and hexagonal Zr2Al and Hf2Al, respectively. The results of elastic constants and phonon dispersion indicate that the present intermetallic compounds are thermodynamically stable. The stability of hexagonal Zr2Al and Hf2Al is analyzed via the electronic density of state, compared to the tetragonal Zr2Al and Hf2Al compounds. For the R2Al intermetallic compounds, the less ductility and strong anisotropy are predicted. The more negative formation enthalpy and thermodynamic stability of R2Al (R = Nb, Zr, Hf) shed light on the Nb2Al, Zr2Al, Hf2Al phases found experimentally in refractory high entropy alloys.
14. Quantitative studies of electric field intensity on atom diffusion of Cu/Ta/Si stacks during annealing
Wang, Lei; Asempah, Isaac; Dong, Song-Tao; Yin, Pian-Pian; Jin, Lei
2017-03-01
It has been shown that enhanced electric field intensity (0-4.0 kV/cm) has an obvious effect on accelerating atom diffusion in Cu/Ta/Si interconnect stacks at 650 °C. The theoretical deduction proves that diffusion coefficient is accelerated proportional to an acceleration factor (1 + a·αE/0.8)2. The analysis indicates that the accelerating effect is mainly attributed to the perturbation of the electric state of the defects and enhanced vacancy and dislocation densities.
15. Diffusion of oxygen in amorphous Al2O3, Ta2O5, and Nb2O5
Nakamura, R.; Toda, T.; Tsukui, S.; Tane, M.; Ishimaru, M.; Suzuki, T.; Nakajima, H.
2014-07-01
The self-diffusivity of oxygen in amorphous Al2O3 (a-Al2O3), a-Ta2O5, and a-Nb2O5 was investigated along with structural analysis in terms of pair distribution function (PDF). The low activation energy, ˜1.2 eV, for diffusion in the oxides suggests a single atomic jump of oxygen ions mediated via vacancy-like defects. However, the pre-exponential factor for a-Ta2O5 and a-Nb2O5 with lower bond energy was two orders of magnitude larger than that for a-Al2O3 with higher bond energy. PDF analyses revealed that the short-range configuration in a-Ta2O5 and a-Nb2O5 was more broadly distributed than that in a-Al2O3. Due to the larger variety of atomic configurations of a-Ta2O5 and a-Nb2O5, these oxides have a higher activation entropy for diffusion than a-Al2O3. The entropy term for diffusion associated with short-range structures was shown to be a dominant factor for diffusion in amorphous oxides.
16. Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy
NASA Technical Reports Server (NTRS)
Harf, F. H.; Tewari, S. N.
1977-01-01
Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.
17. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys
Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.
The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.
18. Complex permeability spectra of PbO and Ta2O5 added nanocrystalline MgCuZn ferrites
V, Seetha Rama Raju
2015-05-01
PbO and Ta2O5 added MgCuZn ferrites are prepared by the Microwave-Hydrothermal (M-H) processing. The nanocrystalline ferrites are sintered to a temperature of 900 °C/4 h. SEM pictures reveal that, the addition of PbO causes a small amount of grain growth, whereas the addition of Ta2O5 causes a fine-grained microstructure. The complex permeability spectra (μ*=μ‧-iμ″) of the prepared samples were measured in the frequency range from 1 MHz to 1.8 GHz, the μ* spectra are analyzed into two magnetization processes with focus on the particle size of ferrite samples. In addition to the spin rotation relaxation in 130-200 MHz, it is initially identified the contribution from reversible domain wall bowing rising at 6-40 MHz. The magnetic state of the ferrite is also influenced by the addition of PbO and Ta2O5. The spin rotation mechanism of the present ferrites is enhanced by the preparation of nanocrystalline samples.
19. Quantifying protein adsorption on combinatorially sputtered Al-, Nb-, Ta- and Ti-containing films with electron microprobe and spectroscopic ellipsometry
Byrne, T. M.; Lohstreter, L.; Filiaggi, M. J.; Bai, Zhijun; Dahn, J. R.
2009-04-01
Although metallic biomaterials are widely used, systematic studies of protein adsorption onto such materials are generally lacking. Combinatorial binary libraries of Al 1-xNb x, Al 1-xTa x, Al 1-xTi x, Nb 1-xTa x, Nb 1-xTi x, and Ta 1-xTi x (0 ⩽ x ⩽ 1) and a ternary library of Al 1-xTi xTa y (0 ⩽ x ⩽ 1 and 0 ⩽ y ⩽ 0.7), along with their corresponding pure element films were sputtered onto glass substrates using a unique magnetron sputtering technique. Films were characterized with wavelength-dispersive spectroscopy (WDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Fibrinogen and albumin adsorption amounts were measured by wavelength-dispersive spectroscopy (WDS) and spectroscopic ellipsometry (SE) equipment, both high throughput techniques with automated motion stage capabilities. Protein adsorption onto these films was found to be closely correlated to the alumina surface fraction, with high alumina content at the surface leading to low amounts of adsorbed fibrinogen and albumin. Protein adsorption amounts obtained with WDS and SE were in good agreement for all films.
20. Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys.
PubMed
Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey
2017-12-01
The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.
1. Controlling Bulk Cu6Sn5 Nucleation in Sn0.7Cu/Cu Joints with Al Micro-alloying
Xian, J. W.; Belyakov, S. A.; Gourlay, C. M.
2016-01-01
We show that dilute Al additions can control the size of primary Cu6Sn5 rods in Sn-0.7Cu/Cu ball grid array joints. In Sn-0.7Cu-0.05Al/Cu joints, the number of primary Cu6Sn5 per mm2 is ˜7 times higher and the mean three-dimensional length of rods is ˜4 times smaller than in Al-free Sn-0.7Cu/Cu joints, while the area fraction of primary Cu6Sn5 is similar. It is shown that epitaxial nucleation of primary Cu6Sn5 occurs on δ-Cu33Al17 or γ 1-Cu9Al4 particles, which are stable in the Sn-0.7Cu-0.05Al melt during holding at 250°C. The observed facet relationships agree well with previously determined orientation relationships between δ-Cu33Al17 and Cu6Sn5 in hypereutectic Sn-Cu-Al alloys and result in a good lattice match with <˜2.5% lattice mismatch on two different interfacial planes.
2. Optical properties analysis of Ta-doped TiO2 thin films on LaAlO3 substrates
Nurfani, Eka; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi
2015-09-01
We study optical properties of Ta-doped TiO2 thin film on LaAlO3 substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 - 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO2 thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO2:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO2 thin film. Due to a processing error by AIP Publishing, an incorrect version of the above article was published on 30 September 2015 that omitted the name of author Toto Winata. AIP Publishing apologizes for this error. All online versions of the article were corrected on 7 October 2015. The author names and affiliations appear correctly above.
3. Characterization of Cu-exchanged SSZ-13: a comparative FTIR, UV-Vis, and EPR study with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios.
PubMed
Giordanino, Filippo; Vennestrøm, Peter N R; Lundegaard, Lars F; Stappen, Frederick N; Mossin, Susanne; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo
2013-09-21
Cu-SSZ-13 has been characterized by different spectroscopic techniques and compared with Cu-ZSM-5 and Cu-β with similar Si/Al and Cu/Al ratios and prepared by the same ion exchange procedure. On vacuum activated samples, low temperature FTIR spectroscopy allowed us to appreciate a high concentration of reduced copper centres, i.e. isolated Cu(+) ions located in different environments, able to form Cu(+)(N2), Cu(+)(CO)n (n = 1, 2, 3), and Cu(+)(NO)n (n = 1, 2) upon interaction with N2, CO and NO probe molecules, respectively. Low temperature FTIR, DRUV-Vis and EPR analysis on O2 activated samples revealed the presence of different Cu(2+) species. New data and discussion are devoted to (i) [Cu-OH](+) species likely balanced by one framework Al atom; (ii) mono(μ-oxo)dicopper [Cu2(μ-O)](2+) dimers observed in Cu-ZSM-5 and Cu-β, but not in Cu-SSZ-13. UV-Vis-NIR spectra of O2 activated samples reveal an intense and finely structured d-d quadruplet, unique to Cu-SSZ-13, which is persistent under SCR conditions. This differs from the 22,700 cm(-1) band of the mono(μ-oxo)dicopper species of the O2 activated Cu-ZSM-5, which disappears under SCR conditions. The EPR signal intensity sets Cu-β apart from the others.
4. Screened coulomb hybrid DFT investigation of band gap and optical absorption predictions of CuVO3, CuNbO3 and Cu5Ta11O30 materials.
PubMed
Harb, Moussab; Masih, Dilshad; Takanabe, Kazuhiro
2014-09-14
We present a joint theoretical and experimental investigation of the optoelectronic properties of CuVO3, CuNbO3 and Cu5Ta11O30 materials for potential photocatalytic and solar cell applications. In addition to the experimental results obtained by powder X-ray diffraction and UV-Vis spectroscopy of the materials synthesized under flowing N2 gas at atmospheric pressure via solid-state reactions, the electronic structure and the UV-Vis optical absorption coefficient of these compounds are predicted with high accuracy using advanced first-principles quantum methods based on DFT (including the perturbation theory approach DFPT) within the screened coulomb hybrid HSE06 exchange-correlation formalism. The calculated density of states are found to be in agreement with the UV-Vis diffuse reflectance spectra, predicting a small indirect band gap of 1.4 eV for CuVO3, a direct band gap of 2.6 eV for CuNbO3, and an indirect (direct) band gap of 2.1 (2.6) eV for Cu5Ta11O30. It is confirmed that the Cu(I)-based multi-metal oxides possess a strong contribution of filled Cu(I) states in the valence band and of empty d(0) metal states in the conduction band. Interestingly, CuVO3 with its predicted small indirect band gap of 1.4 eV shows the highest absorption coefficient in the visible range with a broad absorption edge extending to 886 nm. This novel result offers a great opportunity for this material to be an excellent candidate for solar cell applications.
5. Reduced Cu concentration in CuAl-LPE-grown thin Si layers
SciTech Connect
Wang, T.H.; Ciszek, T.F.; Asher, S.; Reedy, R.
1995-08-01
Cu-Al has been found to be a good solvent system to grow macroscopically smooth Si layers with thicknesses in tens of microns on cast MG-Si substrates by liquid phase epitaxy (LPE) at temperatures near 900{degrees}C. This solvent system utilizes Al to ensure good wetting between the solution and substrate by removing silicon native oxides, and employs Cu to control Al doping into the layers. Isotropic growth is achieved because of a high concentration of solute silicon in the solution and the resulting microscopically rough interface. The incorporation of Cu in the Si layers, however, was a concern since Cu is a major solution component and is generally regarded as a bad impurity for silicon devices due to its fast diffusivity and deep energy levels in the band gap. A study by Davis shows that Cu will nonetheless not degrade solar cell performance until above a level of 10{sup 17} cm{sup -3}. This threshold is expected to be even higher for thin layer silicon solar cells owing to the less stringent requirement on minority carrier diffusion length. But to ensure long term stability of solar cells, lower Cu concentrations in the thin layers are still preferred.
6. Electrical Properties and Superconductivity of MSr2Nd2-xCexCu2O10-δ (M=Ta, Nb)
Zhu, Yingjie; Qian, Yitai; Li, Rukang; Wang, Shiwei; Chen, Zuyao; Chen, Zhaojia; Wang, Nanling; Zhou, Guien
1992-09-01
A new series of layered cuprate compounds MSr2Nd2-xCexCu2O10-δ (M=Ta, Nb) have been synthesized. The structure of the compounds is similar to that of T1-1222. A peak in the R-T curve for the sample of TaSr2Nd1.3Ce0.7Cu2O10-δ has been observed at about 50 K. For the sample of NbSr2Nd1.45Ce0.55Cu2O10-δ, metal-like conductivity behaviour has been observed. We have found superconductivity at about 13.2 K in the samples of NbSr2Nd2-xCexCu2O10-δ (x=0.49, 0.50, 0.51, 0.52).
7. Ab initio molecular dynamics simulations of short-range order in Zr50Cu45Al5 and Cu50Zr45Al5 metallic glasses
DOE PAGES
Huang, Yuxiang; Huang, Li; Wang, C. Z.; ...
2016-02-01
Comparative analysis between Zr-rich Zr50Cu45Al5 and Cu-rich Cu50Zr45Al5 metallic glasses (MGs) is extensively performed to locate the key structural motifs accounting for their difference of glass forming ability. Here we adopt ab initio molecular dynamics simulations to investigate the local atomic structures of Zr50Cu45Al5 and Cu50Zr45Al5 MGs. A high content of icosahedral-related (full and distorted) orders was found in both samples, while in the Zr-rich MG full icosahedrons < 0,0,12,0 > is dominant, and in the Cu-rich one the distorted icosahedral orders, especially < 0,2,8,2 > and < 0,2,8,1 >, are prominent. And the < 0,2,8,2 > polyhedra in Cu50Zr45Al5more » MG mainly originate from Al-centered clusters, while the < 0,0,12,0 > in Zr50Cu45Al5 derives from both Cu-centered clusters and Al-centered clusters. These difference may be ascribed to the atomic size difference and chemical property between Cu and Zr atoms. Lastly, the relatively large size of Zr and large negative heat of mixing between Zr and Al atoms, enhancing the packing density and stability of metallic glass system, may be responsible for the higher glass forming ability of Zr50Cu45Al5.« less
8. Mirroring the dynamic magnetic behavior of magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates
Agra, K.; Gomes, R. R.; Della Pace, R. D.; Dorneles, L. S.; Bohn, F.; Corrêa, M. A.
2015-11-01
We investigate the magnetoimpedance effect in a wide frequency range in magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates. We observe a direct correlation between structural and quasi-static magnetic properties and the magnetoimpedance effect, since they are directly dependent on the nature of the spacer material. Moreover, we verify that all these properties are insensitive to the kind of employed substrate. We compare the magnetoimpedance results measured for multilayers in rigid and flexible substrates and discuss them in terms of different mechanisms that govern the impedances changes, magnetic anisotropy, structural character, and of numerical calculation results found in the literature. The fact that magnetostrictive multilayers can be reproduced in distinct kinds of substrates corresponds to an important advance for their applicability. The results place multilayers grown onto flexible substrates as attractive candidates for application as probe element in the development of MI-based sensor devices.
9. Intermetallic Formation at Interface of Al/Cu Clad Fabricated by Hydrostatic Extrusion and Its Properties.
PubMed
Lee, Jongbeom; Jeong, Haguk
2015-11-01
Al/Cu clad composed of Al core and Cu sheath has been produced by hydrostatic extrusion at 523 K, at an extrusion rate of 27. The prepared specimen was post-annealed at temperatures of 673 K and 773 K for various time durations, and the effect of annealing conditions have been analyzed. The hardness at the interface between Al and Cu matrix of the Al/Cu bimetal clad increases because of annealing. Results indicate that the hardness is more sensitive to annealing temperature than the annealing time. Three kinds of intermetallic compounds (IMC), namely, CuAl, Cu3Al2, and CuAl2, are formed at the Al-Cu interface, upon annealing at 673 K. On the other hand, four kinds of IMCs, namely, Cu4Al3, CuAl, Cu3Al2, CuAl2, are formed at the annealing temperature of 773 K. The growth of each IMC follows the parabolic law as a function of annealing times at certain annealing temperature. The growth rate of each IMC is limited to its interdiffusion rate constant. The IMC Cu4Al3 appears upon annealing at 773 K, and not during annealing at 673 K, because of the higher value of activation energy associated with its formation, when compared to other IMCs.
10. Measured In Situ Atmospheric Ambient Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal, AL, April-May 2015
DTIC Science & Technology
2015-09-01
Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan Gurton, Stephanie Cunningham, and...Aerosol Size-Distributions, Particle Concentrations, and Turbulence Data for RSA TA-6 Test Range, Redstone Arsenal , AL, April–May 2015 by Kristan...Redstone Arsenal , AL Approved for public release; distribution unlimited. ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188
11. Investigation of Al/CuO multilayered thermite ignition
Nicollet, Andréa; Lahiner, Guillaume; Belisario, Andres; Souleille, Sandrine; Djafari-Rouhani, Mehdi; Estève, Alain; Rossi, Carole
2017-01-01
The ignition of the Al/CuO multilayered material is studied experimentally to explore the effects of the heating surface area, layering, and film thickness on the ignition characteristics and reaction performances. After the description of the micro-initiator devices and ignition conditions, we show that the heating surface area must be properly calibrated to optimize the nanothermite ignition performances. We demonstrated experimentally that a heating surface area of 0.25 mm2 is sufficient to ignite a multilayered thermite film of 1.6 mm wide by a few cm long, with a success rate of 100%. A new analytical and phenomenological ignition model based on atomic diffusion across layers and thermal exchange is also proposed. This model considers that CuO first decomposes into Cu2O, and then the oxygen diffuses across the Cu2O and Al2O3 layers before reaching the Al layer, where it reacts to form Al2O3. The theoretical results in terms of ignition response times confirm the experimental observation. The increase of the heating surface area leads to an increase of the ignition response time and ignition power threshold (go/no go condition). We also provide evidence that, for any heating surface area, the ignition time rapidly decreases when the electrical power density increases until an asymptotic value. This time point is referred to as the minimum response ignition time, which is a characteristic of the multilayered thermite itself. At the stoichiometric ratio (Al thickness is half of the CuO thickness), the minimum ignition response time can be easily tuned from 59 μs to 418 ms by tuning the heating surface area. The minimum ignition response time increases when the bilayer thickness increases. This work not only provides a set of micro-initiator design rules to obtain the best ignition conditions and reaction performances but also details a reliable and robust MicroElectroMechanical Systems process to fabricate igniters and brings new understanding of phenomena
12. Beneficial effect of Cu on Ti-Nb-Ta-Zr sputtered uniform/adhesive gum films accelerating bacterial inactivation under indoor visible light.
PubMed
Alhussein, Akram; Achache, Sofiane; Deturche, Regis; Sanchette, Frederic; Pulgarin, Cesar; Kiwi, John; Rtimi, Sami
2017-04-01
This article presents the evidence for the significant effect of copper accelerating the bacterial inactivation on Ti-Nb-Ta-Zr (TNTZ) sputtered films on glass up to a Cu content of 8.3 at.%. These films were deposited by dc magnetron co-sputtering of an alloy target Ti-23Nb-0.7Ta-2Zr (at.%) and a Cu target. The fastest bacterial inactivation of E. coli on this later TNTZ-Cu surface proceeded within ∼75min. The films deposited by magnetron sputtering are chemically homogenous. The film roughness evaluated by atomic force spectroscopy (AFM) on the TNTZ-Cu 8.3 at.% Cu sample presented an RMS-value of 20.1nm being the highest RMS of any Cu-sputtered TNTZ sample. The implication of the RMS value found for this sample leading to the fastest interfacial bacterial inactivation kinetics is also discussed. Values for the Young's modulus and hardness are reported for the TNTZ films in the presence of various Cu-contents. Evaluation of the bacterial inactivation kinetics of E. coli under low intensity actinic hospital light and in the dark was carried out. The stable repetitive bacterial inactivation was consistent with the extremely low Cu-ion release from the samples of 0.4 ppb. Evidence is presented by the bacterial inactivation dependence on the applied light intensity for the intervention of Cu as semiconductor CuO during the bacterial inactivation at the TNTZ-Cu interface. The mechanism of CuO-intervention under light is suggested based on the pH/and potential changes registered during bacterial disinfection.
13. Hydrogen isotope trapping in Al-Cu binary alloys
DOE PAGES
Chao, Paul; Karnesky, Richard A.
2016-01-01
In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high;more » for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.« less
14. Hydrogen isotope trapping in Al-Cu binary alloys
SciTech Connect
Chao, Paul; Karnesky, Richard A.
2016-01-01
In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high; for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.
15. Theoretics-directed effect of copper or aluminum content on the ductility characteristics of Al-based (Al3Ti, AlTi, AlCu, AlTiCu2) intermetallic compounds
Li, Yong; Ma, Xiao-Juan; Liu, Qi-Jun; Kong, Ge-Xing; Ma, Hai-Xia; Wang, Wen-Peng; Wang, Yi-Gao; Jiao, Zhen; Liu, Fu-Sheng; Liu, Zheng-Tang
2016-11-01
First-principle simulations have been applied to investigate the effect of copper (Cu) or aluminum (Al) content on the ductility of Al3Ti, AlTi, AlCu, and AlTiCu2 alloys. The mechanical stable and elastic properties of Al-based intermetallic compounds are researched by density functional theory with the generalized gradient approximation (DFT-GGA). The calculated lattice constants are in conformity with the previous experimental and theoretical data. The deduced elastic constants show that the investigated Al3Ti, AlTi, AlCu, and AlTiCu2 structures are mechanically stable. Shear modulus, Young’s modulus, Poisson’s ratio, and the ratio B/G have also been figured out by using reckoned elastic constants. A further analysis of Young’s modulus and Poisson’s ratio reveals that the third added element copper content has significant effects on the Al-Ti-based ICs ductile character. Project supported by the National Natural Science Foundation of China (Grant Nos. 41674088, 11574254, 11272296, and 11547311), the National Basic Research Program of China (Grant No. 2011CB808201), the Fundamental Research Fund for the Central Universities, China (Grant Nos. 2682014ZT30 and 2682014ZT31), and the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University, China (Grant No. SKLSP201511).
16. Indium Helps Strengthen Al/Cu/Li Alloy
NASA Technical Reports Server (NTRS)
Blackburn, Linda B.; Starke, Edgar A., Jr.
1992-01-01
Experiments on Al/Cu/Li alloys focus specifically on strengthening effects of minor additions of In and Cd. Indium-bearing alloy combines low density with ability to achieve high strength through heat treatment alone. Tensile tests on peak-aged specimens indicated that alloy achieved yield strength approximately 15 percent higher than baseline alloy. Alloy highly suitable for processing to produce parts of nearly net shape, with particular applications in aircraft and aerospace vehicles.
17. Viscous and acoustic properties of AlCu melts
Khusnutdinoff, R. M.; Mokshin, A. V.; Menshikova, S. G.; Beltyukov, A. L.; Ladyanov, V. I.
2016-05-01
The atomic dynamics of the binary Al100- x Cu x system is simulated at a temperature T = 973 K, a pressure p = 1.0 bar, and various copper concentrations x. These conditions (temperature, pressure) make it possible to cover the equilibrium liquid Al100- x Cu x phase at copper concentrations 0 ≤ x ≤ 40% and the supercooled melt in the concentration range 40% ≤ x ≤ 100%. The calculated spectral densities of the time correlation functions of the longitudinal {tilde C_L}( k, ω) and transverse {tilde C_T}( k, ω) currents in the Al100- x Cu x melt at a temperature T = 973 K reveal propagating collective excitations of longitudinal and transverse polarizations in a wide wavenumber range. It is shown that the maximum sound velocity in the v L ( x) concentration dependence takes place for the equilibrium melt at an atomic copper concentration x = 10 ± 5%, whereas the supercooled Al100- x Cu x melt saturated with copper atoms ( x ≥ 40%) is characterized by the minimum sound velocity. In the case of the supercooled melt, the concentration dependence of the kinematic viscosity ν( x) is found to be interpolated by a linear dependence, and a deviation from the linear dependence is observed in the case of equilibrium melt at x < 40%. An insignificant shoulder in the ν( x) dependence is observed at low copper concentrations ( x < 20%), and it is supported by the experimental data. This shoulder is caused by the specific features in the concentration dependence of the density ρ( x).
18. Structure Evolution and Electric Properties of TaN Films Deposited on Al2O3-BASED Ceramic and Glass Substrates by Magnetron Reactive Sputtering
Zhou, Yan Ming; Ma, Yang Zhao; Xie, Zhong; He, Ming Zhi
2014-03-01
Structure evolution and electric properties of tantalum nitride (TaN) films deposited on Al2O3-based ceramic and glass substrates by magnetron reactive sputtering were carried out as a function of the N2-to-Ar flow ratio. The TaN thin films on Al2O3-based ceramic substrates grow with micronclusters composed of numerous nanocrystallites, contains from single-phase of Ta2N grains to TaN, and exhibits high defect density, sheet resistance and negative TCR as the N2-to-Ar flow ratio continuously increases. However, the films on the glass substrates grow in the way of sandwich close-stack, contains from single-phase of Ta2N grains to TaN and Ta3N5 phases with the increase of N2-to-Ar flow ratio. These results indicate that the N2-to-Ar flow ratio and surface characteristic difference of substrates play a dominant effect on the structure and composition of the TaN films, resulting in different electrical properties for the films on Al2O3-based ceramic and the samples on glass substrates.
19. Investigation of new type Cu-Hf-Al bulk glassy alloys
Nagy, E.; Rontó, V.; Sólyom, J.; Roósz, A.
2009-01-01
In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu49Hf42Al9, Cu46Hf45Al9, Cu50Hf42.5Al7.5 and Cu50Hf45Al5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.
20. Selective photocatalytic reduction of CO2 to methanol in CuO-loaded NaTaO3 nanocubes in isopropanol
PubMed Central
Xiang, Tianyu; Chen, Jingshuai; Wang, Yuwen; Yin, Xiaohong; Shao, Xiao
2016-01-01
Summary A series of NaTaO3 photocatalysts were prepared with Ta2O5 and NaOH via a hydrothermal method. CuO was loaded onto the surface of NaTaO3 as a cocatalyst by successive impregnation and calcination. The obtained photocatalysts were characterized by XRD, SEM, UV–vis, EDS and XPS and used to photocatalytically reduce CO2 in isopropanol. This worked to both absorb CO2 and as a sacrificial reagent to harvest CO2 and donate electrons. Methanol and acetone were generated as the reduction product of CO2 and the oxidation product of isopropanol, respectively. NaTaO3 nanocubes loaded with 2 wt % CuO and synthesized in 2 mol/L NaOH solution showed the best activity. The methanol and acetone yields were 137.48 μmol/(g·h) and 335.93 μmol/(g·h), respectively, after 6 h of irradiation. Such high activity could be attributed to the good crystallinity, morphology and proper amount of CuO loading, which functioned as reductive sites for selective formation of methanol. The reaction mechanism was also proposed and explained by band theory. PMID:27335766
1. Oscillatory magnetic anisotropy and spin-reorientation induced by heavy-metal cap in Cu/FeCo/M (M =Hf or Ta): A first-principles study
Ong, P. V.; Kioussis, Nicholas; Amiri, P. Khalili; Wang, K. L.
2016-11-01
Using ab initio electronic structure calculations we have investigated the effect of the thickness of a heavy-metal (HM) cap on the magnetic anisotropy of the Cu /FeCo /HM (n ) thin film where HM = Hf and Ta with thicknesses of n =0 -10 monolayers (MLs). We find that the Hf cap results in a large perpendicular magnetic anisotropy (PMA), which exhibits quasiperiodic oscillation with a period of two MLs. In contrast, the Ta-capped heterostructure exhibits a spin reorientation from out-of-plane to in-plane magnetization orientation at two MLs of Ta. Moreover, the MA remains negative and depends weakly on the Ta-cap thickness beyond the critical thickness. The underlying mechanism of the PMA oscillation is the periodic change in spin-flip spin-orbit coupling between the minority-spin Fe d (x z ,y z ) and majority Fe d (z2) at Γ ¯, which is induced by the hybridization with Hf at the FeCo/Hf interface. Our results help resolve the contradictory experiments regarding the role of the FeCo/Ta interface on the PMA of the MgO/FeCo/Ta junction. The calculations reveal that the ferromagnet/Hf is promising for spintronic applications and that the capping material and thickness are additional parameters for optimizing the functional properties of spintronic devices.
2. Spark Plasma Sintering of AlN Ceramics and Surface Metallization by Refractory Metal of Ti, Nb, Mo, Ta or W at Low Temperature
Kai, Ayako; Johkoh, Naoji; Miki, Toshikatsu
2003-06-01
Aluminum nitride (AlN) powder with no additives was sintered successfully at 1200°C in low-pressure N2 gas using a spark plasma sintering (SPS) process. The density value of the resultant ceramic is as high as 95% of the theoretical one. No openings were left in the grain boundary. If AlN powder is sandwiched by refractory metal (Ti, Nb, Mo, Ta and W) foils during SPS, one obtains AlN ceramics metallized by the refractory metals even at 1200°C. The adhesion strength of Ti, Mo or W to AlN ceramics is sufficiently high, but that of Nb or Ta is low. The characterization of metal/AlN interfaces by X-ray diffractometory (XRD), scanning electron microscopy (SEM) and electron-probe microanalysis (EPMA) has revealed the formation of a thin reaction layer at the Ti/AlN interface, which may be the reason for the high adhesion strength of the Ti/AlN interface. The high adhesion strengths of Mo/AlN and W/AlN might also be associated with thinner metal/AlN reaction layers, which were unfortunately undetectable in our XRD data. The weak adhesion of Nb/AlN and Ta/AlN interfaces was elucidated by large differences in the thermal-expansion coefficient between metallic Nb or Ta and the AlN ceramics.
3. Massive spalling of Cu-Zn and Cu-Al intermetallic compounds at the interface between solders and Cu substrate during liquid state reaction
Kotadia, H. R.; Panneerselvam, A.; Mokhtari, O.; Green, M. A.; Mannan, S. H.
2012-04-01
The interfacial intermetallic compound (IMC) formation between Cu substrate and Sn-3.8Ag-0.7Cu-X (wt.%) solder alloys has been studied, where X consists of 0-5% Zn or 0-2% Al. The study has focused on the effect of solder volume as well as the Zn or Al concentration. With low solder volume, when the Zn and Al concentrations in the solder are also low, the initial Cu-Zn and Al-Cu IMC layers, which form at the solder/substrate interface, are not stable and spall off, displaced by a Cu6Sn5 IMC layer. As the total Zn or Al content in the system increases by increasing solder volume, stable CuZn or Al2Cu IMCs form on the substrate and are not displaced. Increasing concentration of Zn has a similar effect of stabilizing the Cu-Zn IMC layer and also of forming a stable Cu5Zn8 layer, but increasing Al concentration alone does not prevent spalling of Al2Cu. These results are explained using a combination of thermodynamic- and kinetics-based arguments.
4. Martensitic transformation in a Cu-Zn-Al alloy studied by 63Cu and 27Al NMR
Rubini, S.; Dimitropoulos, C.; Gotthardt, R.; Borsa, F.
1991-08-01
27Al and 63Cu line shape, Knight shift, and relaxation rates over a wide range of temperature and external magnetic field are reported for a Cu-Zn-Al alloy displaying a martensitic phase transformation (MPT) at MS=152 K. Changes in line shape, linewidth, and T-12 at the MPT are detected for both nuclei, and are found to be consistent with the local atomic rearrangement occurring at the transformation. A double structure for the 27Al NMR line is observed in a small range of temperature below MS, and interpreted as the superposition of the signals arising from the two coexisting phases. It is shown that the growth of the martensitic phase during the cooling can be monitored by means of the deconvolution of the 27Al spectrum into the two components. From the analysis, it is inferred that a sudden formation of extensive regions in the martensitic phase occurs at the transition. The Knight shift and the Korringa term (T1T)-1 are slightly different in the two phases, indicating a small increase of the density of s electrons at the Fermi surface at the nuclear sites. The enhancement factors of the susceptibility and of the spin-lattice relaxation rate do not seem to be affected by the MPT but are different when measured at the Al or Cu site, indicating a local nonuniform charge-density distribution in the unit cell. A small enhancement of T-11 is observed for both nuclei in the temperature interval in which the growth of the martensite within the austenite is detected. The anomalous contribution to the relaxation is interpreted as due to strong local charge-density fluctuations caused by atomic motion at the interfaces between the two phases. No precursor effects were detected on the NMR parameters above MS, indicating the absence of a static or long-lived microstructure of the product phase and of a static short-wavelength modulation of the lattice.
5. Solidification behavior and structure of Al-Cu alloy welds
SciTech Connect
Brooks, J.A.; Li, M.; Yang, N.C.Y.
1997-09-01
The microsegregation behavior of electron beam (EB) and gas tungsten arc (GTA) welds of Al-Cu alloys covering a range from 0.19 to 7.74 wt% Cu were characterized for dendrite core concentrations and fraction eutectic solidification. Although a single weld speed of 12.7 mm/sec was used, some differences were observed in the segregation behavior of the two weld types. The microsegregation behavior was also modeled using a finite differences technique considering dendrite tip and eutectic undercooling and solid state diffusion. Fairly good agreement was observed between measured and calculated segregation behavior although differences between the two weld types could not be completely accounted for. The concept of dendrite tip undercooling was used to explain the formation of a single through thickness centerline grain in the higher alloy content GTA welds.
6. Growth and oxidation of thin film Al{sub 2}Cu
SciTech Connect
Son, K.A.; Missert, N.A.; Barbour, J.C.; Hren, J.J.; Copeland, R.G.; Minor, K.G.
1999-11-09
Al{sub 2}Cu thin films ({approximately}382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {approximately}3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron Microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30--70 {mu}m wide and 10--25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67{+-}2% Al and 33{+-}2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approximately}5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.
7. Low Temperature Creep of a Titanium Alloy Ti-6Al-2Cb-1Ta-0.8Mo
NASA Technical Reports Server (NTRS)
Chu, H. P.
1997-01-01
This paper presents a methodology for the analysis of low temperature creep of titanium alloys in order to establish design limitations due to the effect of creep. The creep data on a titanium Ti-6Al-2Cb-1Ta-0.8Mo are used in the analysis. A creep equation is formulated to determine the allowable stresses so that creep at ambient temperatures can be kept within an acceptable limit during the service life of engineering structures or instruments. Microcreep which is important to design of precision instruments is included in the discussion also.
8. CO sub 2 induced inhibition of the localized corrosion of aluminum, Al-0. 5% Cu, and Al-2% Cu in dilute HF solution
SciTech Connect
Scully, J.R. . Dept. of Materials Science); Peebles, D.E. )
1991-01-01
This study presents work on corrosion of aluminum, Al-.5% Cu, and Al-2% Cu. Electrochemical tests were performed in dilute HF solutions both with and without CO{sub 2} sparging. It is suggested that CO{sub 2} or its reaction products interact with the passive film so that exposure of Cu in the oxide-solution interface is minimized. CO{sub 2} is investigated as a corrosion inhibitor. 4 refs. (JDL)
9. Photocatalytic property and structural stability of CuAl-based layered double hydroxides
SciTech Connect
Lv, Ming; Liu, Haiqiang
2015-07-15
Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) were successfully synthesized by coprecipitation. Powder X-ray diffraction (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES) and UV–Vis diffuse reflectance spectrum (UV–vis) were used to confirm the formation of as-synthesized solids with good crystal structure. The photocatalytic activity of those LDH materials for CO{sub 2} reduction under visible light was investigated. The experimental results show that CuNiAl-LDHs with narrowest band gap and largest surface areas behave highest efficiency for methanol generation under visible light compared with CuMgAl-LDHs and CuZnAl-LDHs. The CuNiAL-LDH showed high yield for methanol production i.e. 0.210 mmol/g h, which was high efficient. In addition, the influence of the different M{sup 2+} on the structures and stability of the CuMAl-LDHs was also investigated by analyzing the geometric parameters, electronic arrangement, charge populations, hydrogen-bonding, and binding energies by density functional theory (DFT) analysis. The theoretical calculation results show that the chemical stability of LDH materials followed the order of CuMgAl-LDHs>CuZnAl-LDHs>CuNiAl-LDHs, which is just opposite with the photocatalytic activity and band gaps of three materials. - Graphical abstract: The host–guest calculation models and XRD patterns of CuMAl-LDHs: CuMgAl-LDHs (a), CuZnAl-LDHs (b) and CuNiAl-LDHs (c). - Highlights: • Three types of CuMAl layered double hydroxides (LDHs, M=Mg, Zn, Ni) has been synthesized. • CuMgNi shows narrower band gap and more excellent textural properties than other LDHs. • The band gap: CuMgAl based on result from UV–vis analysis. • CuMgAl shows the highest stability and lowest photocatalytic activity, while CuNiAl just opposite.
10. Corrosion behavior of Cu and the Cu-Zn-Al shape memory alloy in simulated uterine fluid.
PubMed
Chen, Bangyi; Liang, Chenghao; Fu, Daojun; Ren, Deming
2005-09-01
Chemical immersion tests, electrochemical methods and atomic absorption spectrometry were employed to investigate the corrosion behavior of Cu and the Cu-Zn-Al shape memory alloy (SMA) in simulated uterine fluid. The effect of pH on corrosion rate and corrosion potential was also investigated. The results indicated that in the static state in simulated uterine fluid, dealuminumification of the Cu-Zn-Al alloy occurred with Cl- combining with aluminum ions to form hydroxyl aluminum chloride. The hydroxyl aluminum chloride hydrolyzed readily and facilitated further dealuminumification corrosion. The corrosion process of Cu and Cu-Zn-Al SMA in simulated uterine fluid was controlled by cathodic reduction of oxygen. Because the tendency for surface ionization is greater for aluminum than for zinc, a compact protective aluminum layer was formed, which inhibited the cathodic reduction of oxygen. Hence, the corrosion rate of Cu-Zn-Al SMA was smaller than that of Cu in simulated uterine fluid. With increasing pH, the corrosion rate of Cu and Cu-Zn-Al SMA in simulated uterine fluid decreased and the open-circuit potential moved in a positive direction.
11. Diffusion Bonding of TA15 and Ti2AlNb Alloys: Interfacial Microstructure and Mechanical Properties
Li, Ping; Ji, Xiaohu; Xue, Kemin
2017-03-01
TA15 and Ti2AlNb alloys were joined by diffusion welding. The influence of holding time on morphology and mechanical properties of the joint was studied under two conditions of different bonding pressure and temperature. The interface structure was analyzed by BSE and EDS. The mechanical properties of joints were tested. The results show that the typical interfacial microstructure consists of lath α-phase (TA15 alloy)/flake α phase + α-interfacial phase + α2 phase/B2-rich phase/Ti2AlNb alloy. When bonding at 920 °C and 15 MPa with increasing holding time, the interface microstructure evolves into flake α phase and distributes as a basket-weave and the interfacial coarse spherical α phase distributes as a line. α2 phase and O phase disappear gradually while the content of the B2 phase increases. The tensile strength of the joints is 870, 892 and 903 MPa, for 120, 150 and 210 min holding time, respectively, while the elongation rises as well. When bonding at 940 °C and 10 MPa with increasing holding time, the interfacial area includes more Widmanstatten structure and B2 phase. The tensile strength of joints decreases from 921 to 908 MPa, while the elongation increases from 12 to 15.5%, for holding 120 and 210 min, respectively. The tendency of plastic fracture also increases with holding time for both temperature-pressure combinations.
12. Microstructure development in Al-Cu-Ag-Mg quaternary alloy
Zhou, Bin; Froyen, L.
2012-01-01
The solidification behaviour of multi-component and multi-phase systems has been largely investigated in binary and ternary alloys. In the present study, a quaternary model system is proposed based on the well known Al-Cu-Ag and Al-Cu-Mg ternary eutectic alloys. The quaternary eutectic composition and temperature were determined by EDS (Energy Dispersive Spectrometry) and DSC (Differential Scanning Calorimetry) analysis, respectively. The microstructure was then characterised by SEM (Scanning Electron Microscope). In the DSC experiments, two types of quaternary eutectics were determined according to their phase composition. For each type of eutectic, various microstructures were observed, which result in different eutectic compositions. Only one of the determined eutectic compositions was further studied by the controlled growth technique in a vertical Bridgeman type furnace. In the initial part of the directionally solidified sample, competing growth between two-phase dendrites and three-phase eutectics was obtained, which was later transformed to competing growth between three-phase and four-phase eutectics. Moreover, silver enrichment was measured at the solidification front, which is possibly caused by Ag sedimentation due to gravity and Ag rejection from dendritic and three-phase eutectic growth, and its accumulation at the solidification front.
13. Thermal, solution and reductive decomposition of Cu-Al layered double hydroxides into oxide products
SciTech Connect
Britto, Sylvia; Vishnu Kamath, P.
2009-05-15
Cu-Al layered double hydroxides (LDHs) with [Cu]/[Al] ratio 2 adopt a structure with monoclinic symmetry while that with the ratio 0.25 adopt a structure with orthorhombic symmetry. The poor thermodynamic stability of the Cu-Al LDHs is due in part to the low enthalpies of formation of Cu(OH){sub 2} and CuCO{sub 3} and in part to the higher solubility of the LDH. Consequently, the Cu-Al LDH can be decomposed thermally (150 deg. C), hydrothermally (150 deg. C) and reductively (ascorbic acid, ambient temperature) to yield a variety of oxide products. Thermal decomposition at low (400 deg. C) temperature yields an X-ray amorphous residue, which reconstructs back to the LDH on soaking in water or standing in the ambient. Solution decomposition under hydrothermal conditions yields tenorite at 150 deg. C itself. Reductive decomposition yields a composite of Cu{sub 2}O and Al(OH){sub 3}, which on alkali-leaching of the latter, leads to the formation of fine particles of Cu{sub 2}O (<1 {mu}m). - Graphical abstract: SEM image of (a) the Cu{sub 2}O-Al(OH){sub 3} composite obtained on reductive decomposition of CuAl{sub 4}-LDH and (b) Cu{sub 2}O obtained on leaching of Al(OH){sub 3} from (a).
14. Electrical conduction mechanism in La3Ta0.5Ga5.3Al0.2O14 single crystals.
PubMed
Yaokawa, Ritsuko; Aota, Katsumi; Uda, Satoshi
2013-12-14
The electrical conduction mechanism in La3Ta0.5Ga5.3Al0.2O14 (LTGA) single crystals was studied by nonstoichiometric defect formation during crystal growth. Since stoichiometric LTGA is not congruent, the single crystal grown from the stoichiometric melt was Ta-poor and Al-rich, where Al atoms were substituted not only in Ga sites but also in Ta sites. The population of the substitutional Al in Ta sites increased with increasing oxygen partial pressure during growth (growth-pO2) in the range from 0.01 to 1 atm. Below 600 °C, substitutional Al atoms in Ta sites were ionized to yield holes, and thus the electrical conductivity of the LTGA crystal depended on temperature and the growth-pO2. The dependence of the electrical conductivity on the growth-pO2 decreased as temperature increased. The temperature rise increases ionic conductivity, for which the dominant carriers are oxygen defects formed by the anion Frenkel reaction.
15. Characterization and Electrical Properties of Al-Doped Cu(In,Ga)Se2 Semiconductors with Various Cu Contents
2014-04-01
Cu(In,Ga)Se2 (CIGSe) semiconductor, which shows record photovoltaic conversion efficiencies near 20%, has become a leading material for thin-film solar cell applications. In this work, Al-doped CIGSe (Al-CIGSe) bulk material with different Cu contents has been prepared by a liquid-phase reactive sintering method at 650°C. Sintering of the Al-CIGSe bulk material has been carried out in the presence of Sb2S3 and Te. The bulk Cu x [(In0.6Al0.1)Ga0.3]Se2 semiconductor was n-type for x = 0.7 and p-type for higher Cu content. The defect chemistry of Al-CIGSe was studied by measuring the electrical properties as a function of copper content. The changes in the conductivity type and carrier concentration were related to defect states involving Cu vacancy and antisite defects of In Cu 2+ and Cu B 2 - in a Cu B IIISe2-type phase. The lattice parameters were in good agreement with other evidence for the existence of different defect states.
16. Vanishing quasiparticle density in a hybrid Al/Cu/Al single-electron transistor
Saira, O.-P.; Kemppinen, A.; Maisi, V. F.; Pekola, J. P.
2012-01-01
The achievable fidelity of many nanoelectronic devices based on superconducting aluminum is limited by either the density of residual nonequilibrium quasiparticles nqp or the density of quasiparticle states in the gap, characterized by Dynes parameter γ. We infer upper bounds nqp<0.033μm-3 and γ<1.6×10-7 from transport measurements performed on Al/Cu/Al single-electron transistors, improving previous results by an order of magnitude. Owing to efficient microwave shielding and quasiparticle relaxation, a typical number of quasiparticles in the superconducting leads is zero.
17. Evaluation of intermediate phases formed on the bonding interface of hot pressed Cu/Al clad materials
Lee, Kwang Seok; Lee, Sangmok; Lee, Jong-Sup; Kim, Yong-Bae; Lee, Geun-An; Lee, Sang-Pill; Bae, Dong-Su
2016-09-01
The aim of the present study is to identify the properties of intermediate phases formed on the bonding interface of hot pressed Cu/Al clad materials by transmission electron microscopy and nano-indentation analyses. Cu/Al clad materials were fabricated by hot pressing under 200 MPa at 250 °C for 1 h and then heat treated at 400 °C for 1 h. Nano-indentation measurement was conducted to evaluate the nanohardness and modulus of the intermediate phases formed between the Cu/Al interfaces. A 3-tier diffusion layer was observed at the Cu/Al interfaces. Knoop microhardness values at the bonding interface were 7 to 11 times that of the Cu and Al matrix metals. The intermediate phases formed at the bonding interface were Al4Cu9, AlCu, and Al2Cu. A mapping analysis confirmed that the Al and Cu particles moved via mutual diffusion toward the intermediate phases formed at the bonding interface. The nanohardness values of η2-AlCu and γ1-Al4Cu9 were 4 to 7 times that of the Cu and Al matrix metals. Nanohardness and Knoop microhardness measurement curves exhibited similar tendencies. The rigidity values of the respective intermediate phases can be arranged in descending order as follows: γ1-Al4Cu9 > η2-AlCu > θ-Al2Cu.
18. Optical properties analysis of Ta-doped TiO{sub 2} thin films on LaAlO{sub 3} substrates
SciTech Connect
Nurfani, Eka; Sutjahja, Inge M.; Rusydi, Andrivo; Darma, Yudi
2015-09-30
We study optical properties of Ta-doped TiO{sub 2} thin film on LaAlO{sub 3} substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 – 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO{sub 2} thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO{sub 2}:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO{sub 2} thin film.
19. Diffusion Brazing of Al6061/15 Vol. Pct Al2O3p Using a Cu-Sn Interlayer
Cooke, Kavian O.; Khan, Tahir I.; Oliver, Gossett D.
2013-06-01
Diffusion brazing of Al-6061 alloy containing 15 vol. pct Al2O3 particles was attempted using Cu-Sn interlayer. Joint formation was attributed to the solid-state interdiffusion of Cu and Sn followed by eutectic formation and subsequent isothermal solidification. Examination of the joint region using scanning electron microprobe analyzer (EPMA), wavelength dispersive spectroscopy (WDS) and X-ray diffraction (XRD) showed the formation of intermetallic phases such as Al7Cu3Mg3, Mg2Cu6Al5, Cu3Sn, and Mg2Sn. The results indicated an increase in joint strength with increasing bonding time giving the highest joint shear strength of 94 MPa at a bonding duration of 3 hours.
20. Physical properties of CuAlO 2 single crystal
Brahimi, R.; Bellal, B.; Bessekhouad, Y.; Bouguelia, A.; Trari, M.
2008-09-01
CuAlO 2 single crystal elaborated by the flux method is a narrow band gap semiconductor crystallizing in the delafossite structure (SG R3¯m). Oxygen insertion in the layered lattice generates p-type conductivity where most holes are trapped in surface-polaron states. The detailed photoelectrochemical characterization and electrochemical impedance spectroscopy (EIS) have been reported for the first time on the single crystal. The study is confined in the basal plan and reversible oxygen insertion is evidenced from the intensity potential characteristics. The oxide is characterized by an excellent chemical stability; the semi-logarithmic plot gave a corrosion potential of-0.82 V SCE and an exchange current density of 0.022 μA cm -2 in KCl (0.5 M) electrolyte. The capacitance measurement ( C-2- V) shows a linear behavior from which a flat band potential of +0.42 V SCE and a doping density NA of 10 16 cm -3 have been determined. The valence band, located at 5.24 eV (0.51 V SCE) below vacuum, is made up of Cu-3d orbital. The Nyquist plot exhibits a pseudo-semicircle whose center is localized below the real axis with an angle of 20°. This can be attributed to a single relaxation time of the electrical equivalent circuit and a constant phase element (CPE). The absence of straight line indicates that the process is under kinetic control.
1. First-principles study of Al-Cu energetics and consequences on athermal formation of Cu-rich compounds
Besson, R.; Kwon, J.; Thuinet, L.; Avettand-Fènoël, M.-N.; Legris, A.
2014-12-01
In spite of its practical interest, the Al-Cu system remains largely unexplored, especially on its Cu-rich side. In order to improve the knowledge of this system, we perform a thorough ab initio study of fcc-based Al-Cu energetics, using the recently proposed M2BCE reciprocal-space cluster expansion approach. We demonstrate the existence of two clearly distinct composition domains, revealing complex ground-state properties. Below 50% Cu, the GP 2 -A l3Cu compound appears as highly favored, in agreement with the well-documented transformation sequence in Al-based alloys. Conversely, the domain between 50% and 80% Cu displays a much shallower landscape, characterized by the existence of a wealth of compounds undergoing fcc →bcc structural instabilities. While such "Bain paths" have been identified for a long time in iron-based alloys, our work gives evidence for their existence in the Al-Cu system. As a striking application, these instabilities provide plausible athermal mechanisms for the formation of Cu-rich phases, in particular for the unexpected emergence of γ1-A l4C u9 , a Hume-Rothery compound observed in various nonequilibrium conditions.
2. Fracture toughness of an Al-Li-Cu-In alloy
NASA Technical Reports Server (NTRS)
Wagner, John A.; Gangloff, Richard P.
1992-01-01
The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates.
3. Temperature effect on ideal shear strength of Al and Cu
Iskandarov, Albert M.; Dmitriev, Sergey V.; Umeno, Yoshitaka
2011-12-01
According to Frenkel’s estimation, at critical shear stress τc=G/2π, where G is the shear modulus, plastic deformation or fracture is initiated even in defect-free materials. In the past few decades it was realized that, if material strength is probed at the nanometer scale, it can be close to the theoretical limit, τc. The weakening effect of the free surface and other factors has been discussed in the literature, but the effect of temperature on the ideal strength of metals has not been addressed thus far. In the present study, we perform molecular dynamics simulations to estimate the temperature effect on the ideal shear strength of two fcc metals, Al and Cu. Shear parallel to the close-packed (111) plane along the [112¯] direction is studied at temperatures up to 800 K using embedded atom method potentials. At room temperature, the ideal shear strength of Al (Cu) is reduced by 25% (22%) compared to its value at 0 K. For both metals, the shear modulus, G, and the critical shear stress at which the stacking fault is formed, τc, decrease almost linearly with increasing temperature. The ratio G/τc linearly increases with increasing temperature, meaning that τc decreases with temperature faster than G. Critical shear strain, γc, also decreases with temperature, but in a nonlinear fashion. The combination of parameters, Gγc/τc, introduced by Ogata as a generalization of Frenkel’s formula, was found to be almost independent of temperature. We also discuss the simulation cell size effect and compare our results with the results of abinitio calculations and experimental data.
4. The hot corrosion of Co-25Cr-10Ni-5Ta-3Al-0.5Y alloy /S-57/
NASA Technical Reports Server (NTRS)
Santoro, G. J.
1978-01-01
A cobalt-base alloy, Co-25Cr-10Ni-5Ta-3Al-0.5Y (S-57), was subjected to hot corrosion in Mach 0.3 burner-rig combustion gases at maximum alloy temperatures of 900 and 1000 C. Various salt concentrations were injected into the burner: 0.5, 2,5, and 10 parts per million synthetic sea salt and 4 parts per million sodium sulfate (Na2SO4). The extent of corrosion was determined by measuring the maximum depth of corrosion in the alloy, and the corrosion process was studied by metallography, X-ray diffraction, scanning electron microscopy, and electron microprobe analysis. While S-57 was found to possess only moderate oxidation resistance at these temperatures, this alloy resisted significant hot corrosion attack under all but the most severe test conditions. The process of hot corrosion attack under the most severe conditions of this study was primarily sulfidation.
5. Band structure, Fermi surface, elastic, thermodynamic, and optical properties of AlZr 3 , AlCu 3 , and AlCu 2 Zr: First-principles study
Parvin, R.; Parvin, F.; Ali, M. S.; Islam, A. K. M. A.
2016-08-01
The electronic properties (Fermi surface, band structure, and density of states (DOS)) of Al-based alloys AlM 3 (M = Zr and Cu) and AlCu2Zr are investigated using the first-principles pseudopotential plane wave method within the generalized gradient approximation (GGA). The structural parameters and elastic constants are evaluated and compared with other available data. Also, the pressure dependences of mechanical properties of the compounds are studied. The temperature dependence of adiabatic bulk modulus, Debye temperature, specific heat, thermal expansion coefficient, entropy, and internal energy are all obtained for the first time through quasi-harmonic Debye model with phononic effects for T = 0 K-100 K. The parameters of optical properties (dielectric functions, refractive index, extinction coefficient, absorption spectrum, conductivity, energy-loss spectrum, and reflectivity) of the compounds are calculated and discussed for the first time. The reflectivities of the materials are quite high in the IR-visible-UV region up to ˜ 15 eV, showing that they promise to be good coating materials to avoid solar heating. Some of the properties are also compared with those of the Al-based Ni3Al compound.
6. Mechanical properties of Al-Cu alloy-SiC composites
SciTech Connect
Anggara, B. S.; Handoko, E.; Soegijono, B.
2014-09-25
The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.
7. Structural and electronic properties of CuI doped with Zn, Ga and Al
Zhu, Jiajie; Gu, Mu; Pandey, Ravindra
2013-08-01
The structural and electronic properties of CuI doped with Zn, Ga and Al are investigated using density functional theory. The calculated results find that the solubility of the cation dopants considered is primarily determined by the difference in the electronic configurations between host and dopants. The order of the formation energy of the dopants is predicted to be E(ZnCu)>E(AlCu)>E(GaCu) in CuI. Furthermore, dopants at the octahedral interstitial sites have lower formation energies as compared to dopants located at the tetrahedral interstitial sites in the lattice. The defect complex consisting of ZnCu and the copper vacancy (ZnCu+VCu) is predicted to be preferred in the lattice, suggesting that incorporation of Zn is expected to enhance the concentration of copper vacancies in CuI.
8. Refinement and growth enhancement of Al2Cu phase during magnetic field assisting directional solidification of hypereutectic Al-Cu alloy
PubMed Central
Wang, Jiang; Yue, Sheng; Fautrelle, Yves; Lee, Peter D.; Li, Xi; Zhong, Yunbo; Ren, Zhongming
2016-01-01
Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites. In this study, a hypereutectic Al-40 wt.%Cu alloy has been directionally solidified under various axial magnetic fields and the morphology of Al2Cu phase was quantified in 3D by means of high resolution synchrotron X-ray tomography. With rising magnetic fields, both increase of Al2Cu phase’s total volume and decrease of each column’s transverse section area were found. These results respectively indicate the growth enhancement and refinement of the primary Al2Cu phase in the magnetic field assisting directional solidification. The thermoelectric magnetic forces (TEMF) causing torque and dislocation multiplication in the faceted primary phases were thought dedicate to respectively the refinement and growth enhancement. To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope. PMID:27091383
9. Refinement and growth enhancement of Al2Cu phase during magnetic field assisting directional solidification of hypereutectic Al-Cu alloy
Wang, Jiang; Yue, Sheng; Fautrelle, Yves; Lee, Peter D.; Li, Xi; Zhong, Yunbo; Ren, Zhongming
2016-04-01
Understanding how the magnetic fields affect the formation of reinforced phase during solidification is crucial to tailor the structure and therefor the performance of metal matrix in situ composites. In this study, a hypereutectic Al-40 wt.%Cu alloy has been directionally solidified under various axial magnetic fields and the morphology of Al2Cu phase was quantified in 3D by means of high resolution synchrotron X-ray tomography. With rising magnetic fields, both increase of Al2Cu phase’s total volume and decrease of each column’s transverse section area were found. These results respectively indicate the growth enhancement and refinement of the primary Al2Cu phase in the magnetic field assisting directional solidification. The thermoelectric magnetic forces (TEMF) causing torque and dislocation multiplication in the faceted primary phases were thought dedicate to respectively the refinement and growth enhancement. To verify this, a real structure based 3D simulation of TEMF in Al2Cu column was carried out, and the dislocations in the Al2Cu phase obtained without and with a 10T high magnetic field were analysed by the transmission electron microscope.
10. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys.
PubMed
Vasconcelos, Angela J; Kikuchi, Rafael H; Barros, André S; Costa, Thiago A; Dias, Marcelino; Moreira, Antonio L; Silva, Adrina P; Rocha, Otávio L
2016-05-31
An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL) and cooling rates (TR) by measuring Vickers microhardness (HV), optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS). The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1) increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET) is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist.
11. Electrical conductivity of dense Al, Ti, Fe, Ni, Cu, Mo, Ta, and W plasmas.
PubMed
DeSilva, A W; Vunni, G B
2011-03-01
We report measurements of electrical conductivity of eight metals in the plasma state at densities ranging from 0.002 to 0.5 times solid density, and with internal energy from 2 to 30 kJ/gm. Data are presented as functions of internal energy and specific volume. Conductivity is observed to fall as the plasma expands for fixed internal energy, and for all but tantalum and titanium shows a minimum at approximately 0.01 times solid density, followed by an increase as the density decreases further.
12. Electrical Conductivity of Dense Al, Ti, Fe, Ni, Cu, Mo, Ta, and W Plasmas
DTIC Science & Technology
2011-06-01
conductivity measurements previously reported by the author and co- workers [1–5] required the use of tabulated equations of state from the SESAME library...Thermophys. 26, 1137 (2005). [6] S. P. Lyon and J. D. Johnson, “ Sesame : the Los Alamos National Laboratory Equation of State Database,” Report No. LA-UR-92...eight metals in the plasma state at densities ranging from 0.002 to 0.5 times solid density, and with internal energy from 2 to 30 kJ/gm. Data are
13. The Low-Lying States of AlCu and AlAg
NASA Technical Reports Server (NTRS)
Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry
1994-01-01
The singlet and triplet states of AlCu and AlAg below about 32 000/cm are studied using the internally contracted multireference configuration-interaction method. A more elaborate study of the X(sup 1)Sum(sup +) ground state of AlCu is undertaken using extended Gaussian basis sets, including the effect of inner-shell correlation and including a perturbational estimate of relativistic effects. Our best estimate of the spectroscopic constants (r(sub 0), DeltaG(sub 1/2), and D(sub 0)) for the X(sup 1)Sum(sup+) state with the experimental values in parentheses are: 4.416(4.420) a(sub 0), 295 (294) /cm, and 2.318 (2.315) eV. The calculations definitively assign the upper state in the observed transition at 14 892/cm to the lowest (sup 1)Prod state. The calculated spectroscopic constants and radiative lifetime for the (sup 1)Prod state are in good agreement with experiment. The calculations support the tentative assignments of Behm et al. for three band systems observed in the visible region between 25 000 and 28 000 / cm. However, the computed spectroscopic constants are in very poor agreement with those deduced from an analysis of the spectra. Analogous theoretical results for AlAg suggest that the (2)(sup 3)Prod, (3)(sup 3)Prod, and (3)(sup 1)Sum(sup +) states account for the bands observed, but not assigned, by Duncan and co-workers.
14. The effects of shockwave profile shape and shock obliquity on spallation in Cu and Ta: kinetic and stress-state effects on damage evolution(u)
SciTech Connect
Gray, George T
2010-12-14
15. Preparation of Al-Cu-Fe-(Sn,Si) quasicrystalline bulks by laser multilayer cladding
Feng, Li-ping; Fleury, Eric; Zhang, Guo-sheng
2012-05-01
(Al65Cu20Fe15)100- x Sn x ( x=0, 12, 20, 30) and Al57Si10Cu18Fe15 powders were cladded on a medium carbon steel (45# steel) substrate by laser multilayer cladding, respectively. The phases and properties of the produced quasicrystalline bulks were investigated. It was found that the main phases in the Al65Cu20Fe15 sample were crystalline λ-Al13Fe4 and icosahedral quasicrystal together with a small volume fraction of θ-Al2Cu phase. The volume fraction of icosahedral phase decreased as the Sn content in the (Al65Cu20Fe15)100- x Sn x samples increased owing to the formation of β-CuSn phase. The increase of Sn content improved the brittleness of the quasicrystal samples. The morphology of the solidification microstructure in the Al57Si10Cu18Fe15 sample changed from elongated shape to spherical shape due to the addition of Si. The nanohardness of the laser multilayer cladded quasicrystal samples was equal to that of the as-cast sample prepared by vacuum quenching. In terms of hardness, the laser cladded Al57Si10Cu18Fe15 quasicrystalline alloy has the highest value among all the investigated samples.
16. Friction Stir Welding of Al-Cu Bilayer Sheet by Tapered Threaded Pin: Microstructure, Material Flow, and Fracture Behavior
Beygi, R.; Kazeminezhad, M.; Kokabi, A. H.; Loureiro, A.
2015-06-01
The fracture behavior and intermetallic formation are investigated after friction stir welding of Al-Cu bilayer sheets performed by tapered threaded pin. To do so, temperature, axial load, and torque measurements during welding, and also SEM and XRD analyses and tensile tests on the welds are carried out. These observations show that during welding from Cu side, higher axial load and temperature lead to formation of different kinds of Al-Cu intermetallics such as Al2Cu, AlCu, and Al4Cu9. Also, existence of Al(Cu)-Al2Cu eutectic structures, demonstrates liquation during welding. The presence of these intermetallics leads to highly brittle fracture and low strength of the joints. In samples welded from Al side, lower axial load and temperature are developed during welding and no intermetallic compound is observed which results in higher strength and ductility of the joints in comparison with those welded from Cu side.
17. Plasmon-exciton couplings in Al-CuCl nanoshells and the effects of oxidation
Yao, Jie; Ji, WenQian; Wu, DaJian; Cheng, Ying; Liu, XiaoJun
2017-04-01
The plasmon-exciton couplings in the Al-CuCl nanoshells have been investigated by using the Mie scattering theory. It is found that the bright dipole mode of the Al nanosphere can couple well with the exciton mode of the outer CuCl shell in the UV region by changing the geometry. The strong plasmon-exciton couplings in the Al-CuCl nanoshell lead to two hybrid plexcitonic modes and hence the Rabi splitting. We study the dispersion curves of the plexcitonic modes of the Al-CuCl nanoshells and obtain the splitting energy of about 135 meV. Furthermore, the influences of the metal oxide on the plasmon-exciton couplings in the Al-CuCl nanoshells have been studied. It is found that the Rabi splitting energy will shrink with the oxide.
18. Radial macrosegregation and dendrite clustering in directionally solidified Al-7Si and Al-19Cu alloys
Ghods, M.; Johnson, L.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.
2016-05-01
Hypoeutectic Al-7 wt% Si and Al-19 wt% Cu alloys were directionally solidified upward in a Bridgman furnace through a range of constant growth speeds and thermal gradients. Though processing is thermo-solutally stable, flow initiated by gravity-independent advection at, slightly leading, central dendrites moves rejected solute out ahead and across the advancing interface. Here any lagging dendrites are further suppressed which promotes a curved solid-liquid interface and the eventual dendrite "clustering" seen in transverse sections (dendrite "steepling" in longitudinal orientations) as well as extensive radial macrosegregation. Both aluminum alloys showed considerable macrosegregation at the low growth speeds (10 and 30 μm s-1) but not at higher speed (72 μm s-1). Distribution of the fraction eutectic-constituent on transverse sections was determined in order to quantitatively describe radial macrosegregation. The convective mechanisms leading to dendrite-steepling were elucidated with numerical simulations, and their results compared with the experimental observations.
19. Investigation on thermal stability of Ta2O5, TiO2 and Al2O3 coatings for application at high temperature
Shang, Peng; Xiong, Shengming; Li, Linghui; Tian, Dong; Ai, Wanjun
2013-11-01
In this paper, tantalum pentoxide (Ta2O5), titanium dioxide (TiO2) and aluminum oxide (Al2O3) coatings are deposited on silicon substrates by ion beam sputtering (IBS). The influences of the thermal exposure at high temperature in air on the surface morphology, roughness, and the structure were investigated. The results indicate that the chemical composition of the as-deposited TiO2 and Ta2O5 coatings are apparently close to the stoichiometry ratios and both of them are amorphous structures. The peaks corresponding to anatase TiO2 appear at 400 °C while the anatase-to-rutile transformation is not observed after 800 °C and 1000 °C bake. Ta2O5 coating crystallizes at 800 °C and 1000 °C to form the hexagonal structure and orthorhombic structure, respectively. TiO2 and Al2O3 single layers all develop catastrophic damage at 400 °C in the form of noted spallation or blisters, whereas there is no visible damage for the Ta2O5 coating even at 1000 °C. To understand possible damage mechanisms, the thermal stress distributions through the thickness of Ta2O5 and TiO2 coatings and the influence of the microstructure transformation are discussed. Finally, some possible approaches to improve the thermal stability are also proposed.
20. A new layered copper oxide - LaSrCuAlO5
Wiley, J. B.; Markham, L. M.; Vaughey, J. T.; McCarthy, T. J.; Sabat, M.
This paper describes the synthesis, crystal structure, and conductivity of a new layered copper oxide, LaSrCuAlO5. The compound was prepared by solid state reaction of Aldrich cupric oxide, strontium carbonate, lanthanum oxide, and aluminum nitrate. The results of XRD studies showed that, although the crystal structure of LaSrCuAlO5 is similar to Ca2Fe2O5 and Ca2AlFeO5, there are significant differences in the ordering of oxygen vacancies. The LaSrCuAlO5 prepared was found to be semiconducting, with a resistivity at room temperature of 0.065 ohm cm.
1. Multiple diffraction in an icosahedral Al-Cu-Fe quasicrystal
Fan, C. Z.; Weber, Th.; Deloudi, S.; Steurer, W.
2011-07-01
In order to reveal its influence on quasicrystal structure analysis, multiple diffraction (MD) effects in an icosahedral Al-Cu-Fe quasicrystal have been investigated in-house on an Oxford Diffraction four-circle diffractometer equipped with an Onyx™ CCD area detector and MoKα radiation. For that purpose, an automated approach for Renninger scans (ψ-scans) has been developed. Two weak reflections were chosen as the main reflections (called P) in the present measurements. As is well known for periodic crystals, it is also observed for this quasicrystal that the intensity of the main reflection may significantly increase if the simultaneous (H) and the coupling (P-H) reflections are both strong, while there is no obvious MD effect if one of them is weak. The occurrence of MD events during ψ-scans has been studied based on an ideal structure model and the kinematical MD theory. The reliability of the approach is revealed by the good agreement between simulation and experiment. It shows that the multiple diffraction effect is quite significant.
2. New investigation of phase equilibria in the system Al-Cu-Si.
PubMed
Ponweiser, Norbert; Richter, Klaus W
2012-01-25
The phase equilibria and invariant reactions in the system Al-Cu-Si were investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe micro analysis (EPMA). Isothermal phase equilibria were investigated within two isothermal sections. The isothermal section at 500 °C covers the whole ternary composition range and largely confirms the findings of previous phase diagram investigations. The isothermal section at 700 °C describes phase equilibria only in the complex Cu-rich part of the phase diagram. A new ternary compound τ was found in the region between (Al,Cu)-γ(1) and (Cu,Si)-γ and its solubility range was determined. The solubility of Al in κ-CuSi was found to be extremely high at 700 °C. In contrast, no ternary solubility in the β-phase of Cu-Al was found, although this phase is supposed to form a complete solid solution according to previous phase diagram assessments. Two isopleths, at 10 and 40 at.% Si, were investigated by means of DTA and a partial ternary reaction scheme (Scheil diagram) was constructed, based on the current work and the latest findings in the binary systems Al-Cu and Cu-Si. The current study shows that the high temperature equilibria in the Cu-rich corner are still poorly understood and additional studies in this area would be favorable.
3. Research of Mechanical Property Gradient Distribution of Al-Cu Alloy in Centrifugal Casting
Sun, Zhi; Sui, Yanwei; Liu, Aihui; Li, Bangsheng; Guo, Jingjie
Al-Cu alloy castings are obtained using centrifugal casting. The regularity of mechanical property gradient distribution of Al-Cu alloy castings with the same centrifugal radius at different positions is investigated. The result shows that the tensile strength, yield strength, elongation and microscope hardness exhibit the following gradient distribution characteristic — high on both sides and low on the center. The trend of mechanical property gradient distribution of Al-Cu alloy increases with the increase in the rotation speed. Moreover, the mechanical properties of casting centerline two sides have asymmetry. The reason is that the grain size of casting centerline two sides and Al2Cu phase and Cu content change correspondingly.
4. Crystal structure of novel compounds in the systems Zr-Cu-Al, Mo-Pd-Al and partial phase equilibria in the Mo-Pd-Al system.
PubMed
Khan, Atta U; Rogl, P; Giester, G
2012-02-28
The crystal structures of three Al-rich compounds have been solved from X-ray single crystal diffractometry: τ(1)-MoPd(2-x)Al(8+x) (x = 0.067); τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) and τ(9)-ZrCu(1-x)Al(4) (x = 0.144). τ(1)-MoPd(2-x)Al(8+x) adopts a unique structure type (space group Pbcm; lattice parameters a = 0.78153(2), b = 1.02643(3) and c = 0.86098(2) nm), which can be conceived as a superstructure of the Mo(Cu(x)Al(1-x))(6)Al(4) type. Whereas Mo-atoms occupy the 4d site, Pd(2) occupies the 4c site, Al and Pd(1) atoms randomly share the 4d position and the rest of the positions are fully occupied by Al. A Bärnighausen tree documents the crystallographic group-subgroup relation between the structure types of Mo(Cu(x)Al(1-x))(6)Al(4) and τ(1). τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) has been confirmed to crystallize with the ThMn(12) type (space group I4/mmm; lattice parameters a = 0.85243(2) and c = 0.50862(3) nm). In total, 4 crystallographic sites were defined, out of which, Zr occupies site 2a, the 8f site is fully occupied by Cu, the 8i site is entirely occupied by Al, but the 8j site turned out to comprise a random mixture of Cu and Al atoms. The compound τ(9)-ZrCu(1-x)Al(4) (x = 0.144) crystallizes in a unique structure type (space group P4/nmm; lattice parameters a = 0.40275(3) and c = 1.17688(4) nm) which exhibits full atom order but a vacancy (14.4%) on the 2c site, shared with Cu atoms. τ(9)-ZrCu(1-x)Al(4) is a superstructure of Cu with an arrangement of three unit cells of Cu in the direction of the c-axis. A Bärnighausen tree documents this relationship. The ZrCu(1-x)Al(4) type (n = 3) is part of a series of structures which follow this building principle: Cu (n = 1), TiAl(3) (n = 2), τ(5)-TiNi(2-x)Al(5) (n = 4), HfGa(2) (n = 6) and Cu(3)Pd (n = 7). A partial isothermal section for the Al-rich part of the Mo-Pd-Al system at 860 °C has been established with two ternary compounds τ(1)-MoPd(2-x)Al(8+x) and τ(2) (unknown structure). The
5. Role of the (Ta/Nb)O{sub x}/Al{sub 2}O{sub 3} interface on the flatband voltage shift for Al{sub 2}O{sub 3}/(Ta/Nb)O{sub x}/Al{sub 2}O{sub 3} multilayer charge trap capacitors
SciTech Connect
Nabatame, Toshihide; Ohi, Akihiko; Ito, Kazuhiro; Takahashi, Makoto; Chikyo, Toyohiro
2015-01-15
The authors studied the characteristics of Si/Al{sub 2}O{sub 3}/(Ta/Nb)O{sub x}/Al{sub 2}O{sub 3}/SiO{sub 2}/Pt charge trap capacitors fabricated by atomic layer deposition and postmetallization annealing at 400 °C. Al{sub 2}O{sub 3} and (Ta/Nb)O{sub x} films are amorphous and have negligible fixed charges. In program mode, a flatband voltage (V{sub fb}) drastically shifts toward the positive direction at a short program time of 10{sup −4} s. A large V{sub fb} shift of approximately 4 V arises after programming at 1 mC/cm{sup 2} because there is a large difference in the conduction band offset between the (Ta/Nb)O{sub x}-charge trapping layer (TNO-CTL) and the Al{sub 2}O{sub 3}-blocking layer (AlO-BL) (1.8 eV). In the retention mode, most of the trapped electrons in the TNO-CTL transfers across the Al{sub 2}O{sub 3}-tunneling layer (AlO-TL) rather than the AlO-BL. The thickness of the AlO-TL affects the V{sub fb} shift degradation behavior in the retention mode. The injected electrons are dominantly located at the TNO-CTL/ALO-BL interface, determined from the thickness dependence of the TNO-CTL on the V{sub fb} shift.
6. Luminescence of delafossite-type CuAlO2 fibers with Eu substitution for Al cations
PubMed Central
Liu, Yin; Gong, Yuxuan; Mellott, Nathan P.; Wang, Bu; Ye, Haitao; Wu, Yiquan
2016-01-01
Abstract CuAlO2 has been examined as a potential luminescent material by substituting Eu for Al cations in the delafossite structure. CuAlO2:Eu3+ nanofibers have been prepared via electrospinning for the ease of mitigating synthesis requirements and for future optoelectronics and emerging applications. Single-phase CuAlO2 fibers could be obtained at a temperature of 1100 °C in air. The Eu was successfully doped in the delafossite structure and two strong emission bands at ~405 and 610 nm were observed in the photoluminescence spectra. These bands are due to the intrinsic near-band-edge transition of CuAlO2 and the f-f transition of the Eu3+ activator, respectively. Further electrical characterization indicated that these fibers exhibit semiconducting behavior and the introduction of Eu could act as band-edge modifiers, thus changing the thermal activation energies. In light of this study, CuAlO2:Eu3+ fibers with both strong photoluminescence and p-type conductivity could be produced by tailoring the rare earth doping concentrations. PMID:27877870
7. Evaluation of the microstructure of Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 4
NASA Technical Reports Server (NTRS)
Pickens, Joseph R.; Kumar, K. S.; Brown, S. A.; Gayle, Frank W.
1991-01-01
Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy designed to have ultrahigh strength and to serve in aerospace applications. The alloy displays significantly higher strength than competitive alloys in both naturally aged and artificially aged tempers. The strengthening phases in such tempers have been identified to, in part, explain the mechanical properties attained. In general, the alloy is strengthened by delta prime Al3Li and Guinier-Preston (GP) zones in the naturally aged tempers. In artificially aged tempers in slightly underaged conditions, strengthening is provided by several phases including GP zones, theta prime Al2Cu, S prime Al2CuMg, T(sub 1) Al2CuLi, and possibly a new phase. In the peak strength artificially aged tempers, T(sub 1) is the predominant strengthening phase.
8. Further Precipitation Reactions Associated with Beta’ (Al3Zr) Particles in Al-Li-Cu-Mg-Zr Alloys
DTIC Science & Technology
1988-12-01
Gregson 8’ precipitation in Al-Li-Mg-Cu-Zr alloys. H.M. Flower J. Mater. Sci. Lett., 3, 829 (1984) 5 P.L. Makin On the ageing of an aluminium-lithium...Technol., 2, 349 (1986) 8 H.M. Flower The effect of composition and heat treatment upon the et al microstructure/property relationships in Al-Li-Cu-Mg...1119 REFERENCES concluded) No. Author Title, etc 10 P.J. Gregon Microstructural control of toughness in aluminium- H.M. Flower lithium alloys. Acta
9. Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires
SciTech Connect
Borza, F. Lupu, N.; Dobrea, V.; Chiriac, H.
2015-05-07
Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems.
10. Surface characteristics and protein adsorption on combinatorial binary Ti-M (Cr, Al, Ni) and Al-M (Ta, Zr) library films.
PubMed
Bai, Zhijun; Filiaggi, M J; Sanderson, R J; Lohstreter, L B; McArthur, M A; Dahn, J R
2010-02-01
Systematic studies of protein adsorption onto metallic biomaterial surfaces are generally lacking. Here, combinatorial binary library films with compositional gradients of Ti(1-x)Cr(x), Ti(1-x)Al(x), Ti(1-x)Ni(x) and Al(1-x)Ta(x), (0 Al(1-y)Zr(y) (0 < y <0.5) as well as corresponding pure metal films were sputtered onto clean Si surfaces. Bulk and surface chemistry, film microstructure, and surface roughness were subsequently correlated to fibrinogen or albumin adsorption measured using a high throughput wavelength dispersive spectroscopy technique. X-ray diffraction revealed these binary films to have crystalline phases present primarily at either extreme of the compositional library and an amorphous zone dominating along the gradient. These mirror-like films were generally found by atomic force microscopy to have a roughness of less than 8 nm, with any relative increases in roughness consistent with the development of crystalline phases. Surface chemistry by quantitative high-resolution X-ray photoelectron spectroscopy differed significantly from bulk film composition as measured by electron microprobe, with TiO(2) and Al(2)O(3) preferentially forming on the binary film surfaces. Correspondingly, protein adsorption onto these films closely correlated with their surface oxide fractions. Aluminum deposited as either a constant-composition film or as part of a binary library consistently adsorbed the least amount of albumin and fibrinogen, with alumina-enrichment of the surface oxide correlating with this adsorption. Overall, this combinatorial materials approach coupled with high-throughput surface analytical methods provides an efficient method of screening potential metallic biomaterials that may enable as well systematic studies of surface properties driving protein adsorption on these metal / metal oxide systems.
11. Microstructural variations in Cu/Nb and Al/Nb nanometallic multilayers
SciTech Connect
Polyakov, M. N.; Hodge, A. M.; Courtois-Manara, E.; Wang, D.; Kuebel, C.; Chakravadhanula, K.
2013-06-17
Miscible (Al/Nb) and immiscible (Cu/Nb) nanometallic multilayer systems were characterized by means of transmission electron microscopy techniques, primarily by automated crystallographic orientation mapping, which allows for the resolution of crystal structures and orientations at the nanoscale. By using this technique, distinctive Nb orientations in relation to the crystallographic state of the Al and Cu layer structures can be observed. Specifically, the Al and Cu layers were found to consist of amorphous, semi-amorphous, and crystalline regions, which affect the overall multilayer microstructure.
12. The shape memory capability and life of Cu-Al-Be-X alloys
SciTech Connect
Dong, Y.Y.; Dar, K.Z. ); Wang, T.M. ); Zin, S.J. )
1994-09-01
The shape memory capacity and the shape memory life of three alloys of the Cu-11.6Al-0.4Be-X type have been investigated using the strain angle restoration method and compared with the alloy Cu-25Zn-4Al. The alloys were subjected to various normalizing and normalizing plus aging treatments, and all were found to possess excellent shape memory properties. The alloy Cu-11.6Al-0.4Be-0.2Cr demonstrated the best shape memory capacity and life.
13. High Elastic Moduli of a 54Al2O3-46Ta2O5 Glass Fabricated via Containerless Processing.
PubMed
Rosales-Sosa, Gustavo A; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki; Yanaba, Yutaka; Mizoguchi, Teruyasu; Umada, Takumi; Okamura, Kohei; Kato, Katsuyoshi; Watanabe, Yasuhiro
2015-10-15
Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. Moreover, thinner and lighter glasses are desired for the fabrication of windows in buildings and cars, cover glasses for smart-phones and substrates in Thin-Film Transistor (TFT) displays. In this work, we report a 54Al2O3-46Ta2O5 glass fabricated by aerodynamic levitation which possesses one of the highest elastic moduli and hardness for oxide glasses also displaying excellent optical properties. The glass was colorless and transparent in the visible region, and its refractive index nd was as high as 1.94. The measured Young's modulus and Vickers hardness were 158.3 GPa and 9.1 GPa, respectively, which are comparable to the previously reported highest values for oxide glasses. Analysis made using (27)Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy revealed the presence of a significantly large fraction of high-coordinated Al in addition to four-coordinated Al in the glass. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta(5+) ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5.
14. High Elastic Moduli of a 54Al2O3-46Ta2O5 Glass Fabricated via Containerless Processing
PubMed Central
Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki; Yanaba, Yutaka; Mizoguchi, Teruyasu; Umada, Takumi; Okamura, Kohei; Kato, Katsuyoshi; Watanabe, Yasuhiro
2015-01-01
Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. Moreover, thinner and lighter glasses are desired for the fabrication of windows in buildings and cars, cover glasses for smart-phones and substrates in Thin-Film Transistor (TFT) displays. In this work, we report a 54Al2O3-46Ta2O5 glass fabricated by aerodynamic levitation which possesses one of the highest elastic moduli and hardness for oxide glasses also displaying excellent optical properties. The glass was colorless and transparent in the visible region, and its refractive index nd was as high as 1.94. The measured Young’s modulus and Vickers hardness were 158.3 GPa and 9.1 GPa, respectively, which are comparable to the previously reported highest values for oxide glasses. Analysis made using 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy revealed the presence of a significantly large fraction of high-coordinated Al in addition to four-coordinated Al in the glass. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta5+ ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5. PMID:26468639
15. High Elastic Moduli of a 54Al2O3-46Ta2O5 Glass Fabricated via Containerless Processing
Rosales-Sosa, Gustavo A.; Masuno, Atsunobu; Higo, Yuji; Inoue, Hiroyuki; Yanaba, Yutaka; Mizoguchi, Teruyasu; Umada, Takumi; Okamura, Kohei; Kato, Katsuyoshi; Watanabe, Yasuhiro
2015-10-01
Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. Moreover, thinner and lighter glasses are desired for the fabrication of windows in buildings and cars, cover glasses for smart-phones and substrates in Thin-Film Transistor (TFT) displays. In this work, we report a 54Al2O3-46Ta2O5 glass fabricated by aerodynamic levitation which possesses one of the highest elastic moduli and hardness for oxide glasses also displaying excellent optical properties. The glass was colorless and transparent in the visible region, and its refractive index nd was as high as 1.94. The measured Young’s modulus and Vickers hardness were 158.3 GPa and 9.1 GPa, respectively, which are comparable to the previously reported highest values for oxide glasses. Analysis made using 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy revealed the presence of a significantly large fraction of high-coordinated Al in addition to four-coordinated Al in the glass. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta5+ ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5.
16. Thermoelectric Properties of Fe2VAl and Fe2V0.75M0.25Al (M = Mo, Nb, Ta) Alloys: First-Principles Calculations
2016-02-01
Ab initio investigations of the structural, electronic, and thermoelectric properties of stoichiometric Fe2VAl full-Heusler alloy and Fe2V0.75M0.25Al (M = Mo, Nb, Ta) nonstoichiometric alloys have been performed using density functional theory on the basis of the full-potential linearized augmented plane wave method with the generalized gradient approximation. The thermoelectric properties are calculated using semiclassical Boltzmann transport theory within the constant-relaxation-time approximation. Fe2VAl, Fe2V0.75Nb0.25Al, and Fe2V0.75Ta0.25Al alloys are found to exhibit a semimetallic behavior, while Fe2V0.75Mo0.25Al acts as a metal. We found that Fe2VAl has a pseudogap of about -0.13 eV, whereas Fe2V0.75Nb0.25Al and Fe2V0.75Ta0.25Al are characterized by a zero energy gap around the Fermi level. Thermoelectric calculations showed that Fe2VAl has both p- and n-type thermoelectric properties, where the p-type thermopower values are found to be higher than those of n-type. The Seebeck coefficient S has maximum values from 20 μV K-1 to 125 μV K-1 and from 19 μV K-1 to 90 μV K-1 in the temperature range of 100 K to 800 K for p- and n-type, respectively. The maximum thermoelectric properties can be obtained at carrier concentration of the order of 1020 cm-3 for p- or n-type doping. Substitution of Nb and Ta atoms enhanced the thermoelectric properties to 150 μV K-1 at 800 K. The optimum concentrations for the three partially substituted alloys were found to be between 1020 cm-3 and 1021 cm-3.
17. Microstructure characteristics and mechanical properties of laser-TIG hybrid welded dissimilar joints of Ti-22Al-27Nb and TA15
Zhang, Kezhao; Lei, Zhenglong; Chen, Yanbin; Liu, Ming; Liu, Yang
2015-10-01
Laser-TIG-hybrid-welding (TIG - tungsten inert gas) process was successfully applied to investigate the microstructure and tensile properties of Ti-22Al-27Nb/TA15 dissimilar joints. The HAZ of the arc zone in Ti-22Al-27Nb was characterized by three different regions: single B2, B2+α2 and B2+α2+O, while the single B2 phase region was absent in the HAZ of the laser zone. As for the HAZ in TA15 alloy, the microstructure mainly contained acicular α‧ martensites near the fusion line and partially remained the lamellar structure near the base metal. The fusion zone consisted of B2 phase due to the relatively high content of β phase stabilizing elements and fast cooling rate during the welding process. The tensile strength of the welds was higher than that of TA15 alloy because of the fully B2 microstructure in the fusion zone, and the fracture preferentially occurred on the base metal of TA15 alloy during the tensile tests at room temperature and 650 °C.
18. Effect of current reversal on the failure mechanism of Al-Cu-Si narrow interconnects
SciTech Connect
Kim, C.U.; Kang, S.H.; Morris, J.W. Jr. |
1996-02-01
The work reported here concerns the effect of a brief exposure to a reversed current on the electromigration failure of narrow Al-Cu thin-film conducting lines. While the precise mechanism by which Cu retards electromigration in Al-Cu alloys is not fully understood, the consistent observation that electromigration failure is preceded by the sweeping of Cu from the failure site can be used to improve electromigration resistance by stabilizing the distribution of Cu. One way of doing this is to expose the Al-Cu line to a reverse current for some period of time. The present work shows that this method is particularly effective in thin lines with quasi-bamboo microstructures. It has the effect of building a reservoir of Cu at the upstream ends of the polygranular segments that are the preferred failure sites, and significantly increases both the mean time of failure, and the time to first failure of a distribution of lines. It can be inferred from these results that Al-Cu lines that conduct alternating current should be exceptionally resistant to electromigration failure. 11 refs., 8 figs.
19. Mixed oxide semiconductor CuInAlO4 nanoparticles: synthesis, structure and photocatalytic properties
Xu, Jian; Qin, Chuanxiang; Bi, Shala; Wan, Yingpeng; Huang, Yanlin; Wang, Yaorong; Seo, Hyo Jin
2017-01-01
CuInAlO4 nanoparticles were synthesized via the facile sol-gel route. The phase formations were investigated by x-ray powder diffraction and structure refinements. The morphological characteristic of the nano-oxides was tested with scanning electron microscopy, transmission electron microscopy, energy-dispersive spectra, N2-adsorption-desorption isotherms and the x-ray photoelectron spectrum. The optical absorption, band energy and structures of the nanoparticles were measured. CuInAlO4 has wide optical absorption from UV to visible wavelength. The nano-oxides have a narrow band energy of 2.191 eV. The photocatalysis ability of CuInAlO4 nanoparticles was confirmed by its efficient photodegradation on methylene blue (MB) dye under the excitation of the visible wavelengths: CuInAlO4 demonstrates efficient photocatalysis on MB photodegradation.
20. Finite Element Modeling for the Structural Analysis of Al-Cu Laser Beam Welding
Hartel, Udo; Ilin, Alexander; Bantel, Christoph; Gibmeier, Jens; Michailov, Vesselin
Laser beam welding of aluminum and copper (Al-Cu) materials is a cost efficient joining technology to produce e.g. connector elements for battery modules. Distortion low connections can be achieved, which have electrical favorable properties. Numerical simulation of the laser beam welding process of Al-Cu dissimilar materials can provide further insight into principal process mechanisms and mechanical response of the joint parts. In this paper a methodology is introduced to investigate the structural behavior of Al-Cu joints in overlap joint with respect to welding distortions and residual stresses. First the material model of the homogeneous base materials are validated. Next, a generic material model approach is used to simulate the structural behavior of heterogeneous Al-Cu connections.
1. Complex metallic surface phases in the Al/Cu(111) system: An experimental and computational study
Duguet, T.; Gaudry, E.; Deniozou, T.; Ledieu, J.; de Weerd, M. C.; Belmonte, T.; Dubois, J. M.; Fournée, V.
2009-11-01
The growth of complex intermetallics as surface alloys is investigated by annealing Al thin films deposited on Cu(111) substrate in ultrahigh vacuum. Already at room temperature, the large lattice mismatch between Al and Cu results in interfacial intermixing. Upon annealing, various phases are formed by diffusion depending on the thickness of the Al films and the annealing temperature. The surface structures are characterized by scanning tunneling microscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy. Three different superlattice phases are identified as well as the complex Hume-Rothery γ-Al4Cu9 phase. The epitaxial relationships between the surface phases and the Cu(111) substrate are determined. We further investigate the electronic structure of the γ phase by density functional calculations. Experimental valence bands are compared to calculated density of states and simulated STM images are used to identify possible bulk planes appearing as surface termination.
2. CuO nanoparticles encapsulated inside Al-MCM-41 mesoporous materials via direct synthetic route
PubMed Central
Huo, Chengli; Ouyang, Jing; Yang, Huaming
2014-01-01
Highly ordered aluminum-containing mesoporous silica (Al-MCM-41) was prepared using attapulgite clay mineral as a Si and Al source. Mesoporous complexes embedded with CuO nanoparticles were subsequently prepared using various copper sources and different copper loadings in a direct synthetic route. The resulting CuO/Al-MCM-41 composite possessed p6mm hexagonally symmetry, well-developed mesoporosity, and relatively high BET surface area. In comparison to pure silica, these mesoporous materials embedded with CuO nanoparticles exhibited smaller pore diameter, thicker pore wall, and enhanced thermal stability. Long-range order in the aforementioned samples was observed for copper weight percentages as high as 30%. Furthermore, a significant blue shift of the absorption edge for the samples was observed when compared with that of bulk CuO. H2-TPR measurements showed that the direct-synthesized CuO/Al-MCM-41 exhibited remarkable redox properties compared to the post-synthesized samples, and most of the CuO nanoparticles were encapsulated within the mesoporous structures. The possible interaction between CuO and Al-MCM-41 was also investigated. PMID:24419589
3. Cu-doped AlN: A possible spinaligner at room-temperature grown by molecular beam epitaxy?
SciTech Connect
Ganz, P. R.; Schaadt, D. M.
2011-12-23
Cu-doped AlN was prepared by plasma assisted molecular beam epitaxy on C-plane sapphire substrates. The growth conditions were investigated for different Cu to Al flux ratios from 1.0% to 4.0%. The formation of Cu-Al alloys on the surface was observed for all doping level. In contrast to Cu-doped GaN, all samples showed diamagnetic behavior determined by SQUID measurements.
4. Microstructure and Erosion Resistance Performance of ZrAlN/Cu Coating
Du, Jun; Zhu, Xiaoying; Zhang, Ping; Cai, Zhihai
ZrAlN/Cu coating has been deposited onto Ti-6Al-4 V substrate by reactive magnetron sputtering in order to improve its erosion resistance. The morphology and microstructure were studied combined with Field Emission Scanning Electron Microscrope(FSEM), X-ray Diffraction(XRD), X-ray Photoelectron Spectroscopy(XPS) and Transmission Electron Microscopy(TEM). Coatings hardness and toughness were measured by nano-indentation method and Vicker indentation method respectively. It has been found that Zr0.79Al0.19Cu0.02N coating possess dense columnar structure with 20∼40 nm columnar grains exbibiting (100) preferential orientation. XRD reflection peaks slightly shifts to higher angle, showing some of 19at%Al and 2at%Cu substitutely dissolves into face-centered cubic(FCC) ZrN lattice, XPS proves the existence of AlN and Cu phase in coating. Zr0.79Al0.19Cu0.02N coating demonstrates best erosion resistance at 15°∼90° impingement angle compared with Ti6Al4 V substrate, ZrN and Zr0.80Al0.20N coating, attributing to combination of high hardness(40.7 GPa) and good toughness.
5. Shape Memory effect and Superelasticity in the [001] Single crystals of a FeNiCoAlTa Alloy with γ-α'-Thermoelastic Martensitic Transformations
Chumlyakov, Yu. I.; Kireeva, I. V.; Kretinina, I. V.; Keinikh, K. S.; Kuts, O. A.; Kirillov, V. A.; Karaman, I.; Maier, H.
2013-12-01
Using single crystals of a Fe - 28% Ni - 17% Co - 11.5% Al - 25% Ta (аt.%) alloy, oriented for tensile loading along the [001] direction, the shape-memory (SME) and superelasticity (SE) effects caused by reversible thermoelastic martensitic transformations (MTs) from a high-temperature fcc-phase into a bctmartensite are investigated. It is demonstrated that the conditions necessary for the thermoelastic MTs to occur are achieved by aging at 973 K within the time interval (t) from 0.5 to 7.0 hours, which is accompanied by precipitation of the γ'-phase particles, (FeNiCo)3(AlTa), whose d < 8-12 nm. When the size of the γ'-precipitates becomes as large as d ≥ 8-12 nm, the MT becomes partially reversible. The physical causes underlying the kinetics of thermoelstic reversible fcc-bct MTs are discussed.
6. Investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al alloy with Ag and Mn additions
SciTech Connect
Silva, R.A.G.; Paganotti, A.; Gama, S.; Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A.
2013-01-15
The investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al, Cu-11%Al-3%Ag, Cu-11%Al-10%Mn and Cu-11%Al-10%Mn-3%Ag alloys was made using microhardness measurements, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersion X-ray spectroscopy and magnetic moment change with applied field measurement. The results indicated that the Mn addition changes the phase stability range, the microhardness values and makes undetectable the eutectoid reaction in annealed Cu-11%Al and Cu-11%Al-3%Ag alloys while the presence of Ag does not modify the phase transformation sequence neither microhardness values of the annealed Cu-11%Al and Cu-11%Al-10%Mn alloys, but it increases the magnetic moment of this latter at about 2.7 times and decreases the rates of eutectoid and peritectoid reactions of the former. - Highlights: Black-Right-Pointing-Pointer The microstructure of Cu-Al alloy is modified in the Ag presence. Black-Right-Pointing-Pointer ({alpha} + {gamma}) phase is stabilized down to room temperature when Ag is added to Cu-Al alloy. Black-Right-Pointing-Pointer Ag-rich phase modifies the magnetic characteristics of Cu-Al-Mn alloy.
7. Nb and Ta layer doping effects on the interfacial energetics and electronic properties of LaAlO3/SrTiO3 heterostructure: first-principles analysis.
PubMed
Nazir, Safdar; Behtash, Maziar; Cheng, Jianli; Luo, Jian; Yang, Kesong
2016-01-28
The two-dimensional electron gas (2DEG) formed at the n-type (LaO)(+1)/(TiO2)(0) interface in the polar/nonpolar LaAlO3/SrTiO3 (LAO/STO) heterostructure (HS) has emerged as a prominent research area because of its great potential for nanoelectronic applications. Due to its practical implementation in devices, desired physical properties such as high charge carrier density and mobility are vital. In this respect, 4d and 5d transition metal doping near the interfacial region is expected to tailor electronic properties of the LAO/STO HS system effectively. Herein, we studied Nb and Ta-doping effects on the energetics, electronic structure, interfacial charge carrier density, magnetic moment, and the charge confinements of the 2DEG at the n-type (LaO)(+1)/(TiO2)(0) interface of LAO/STO HS using first-principles density functional theory calculations. We found that the substitutional doping of Nb(Ta) at Ti [Nb(Ta)@Ti] and Al [Nb(Ta)@Al] sites is energetically more favorable than that at La [Nb(Ta)@La] and Sr [Nb(Ta)@Sr] sites, and under appropriate thermodynamic conditions, the changes in the interfacial energy of HS systems upon Nb(Ta)@Ti and Nb(Ta)@Al doping are negative, implying that the formation of these structures is energetically favored. Our calculations also showed that Nb(Ta)@Ti and Nb(Ta)@Al doping significantly improve the interfacial charge carrier density with respect to that of the undoped system, which is because the Nb(Ta) dopant introduces excess free electrons into the system, and these free electrons reside mainly on the Nb(Ta) ions and interfacial Ti ions. Hence, along with the Ti 3d orbitals, the Nb 4d and Ta 5d orbitals also contribute to the interfacial metallic states; accordingly, the magnetic moments on the interfacial Ti ions increase significantly. As expected, the Nb@Al and Ta@Al doped LAO/STO HS systems show higher interfacial charge carrier density than the undoped and other doped systems. In contrast, Nb@Ti and Ta@Ti doped systems may
8. Optical Measurement of Forming Limit and Formability of Cu/Al Clad Metals
Sun, Tao; Liang, Jin; Guo, Xiang; Ren, Maodong; Wang, Lizhong
2015-04-01
A digital image deformation measurement and analysis control system (XJTUDIC 8.0) was employed to measure the forming limit strain for Cu/Al clad metals produced via explosive welding technique. A contrast test between the digital image correlation (DIC) method and the conventional grid method was also implemented using the SPCC sheet metal forming limit test. The effect of heat treatment and contact status on forming limit was discussed based on the forming limit strain of Cu/Al clad metals. The interfacial and fracture structures were analyzed using scanning electron microscopy. The fracture site was predicted by finite element method. Results demonstrate that the forming limit curve of Cu/Al clad metals through DIC is more likely to reflect the formability of SPCC accurately. The forming limit of the clad with Al in the inner layer is higher than that of the clad with Cu in the inner layer. The formability of the annealed clads is superior to that of the non-annealed clads. The local interface failure induces the microcracks in Cu/Al clad metals during the forming process, which could be the main failure mode. With the finite element method, the fracture location of Cu/Al clad metals caused by uniaxial tensile during the forming limit test using DIC method is predicted accurately.
9. Formation of CuAlO2 Film by Ultrasonic Spray Pyrolysis
Iping, S.; Lockman, Zainovia; Hutagalung, S. D.; Kamsul, A.; Matsuda, Atsunori
2011-10-01
Smooth, crack free and homogenous CuAlO2 film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO3)2.3H2O and 90 mmol Al(NO3)3.9H2O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO2 can be detected for samples prepared by spraying the precursor mist at temperature of > 550 °C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO2.
10. Azide SHS of aluminium nitride nanopowder and its application for obtaining Al-Cu-AlN cast nanocomposite
Titova, Y. V.; Sholomova, A. V.; Kuzina, A. A.; Maidan, D. A.; Amosov, A. P.
2016-11-01
Method of azide self-propagating high-temperature synthesis (SHS-Az), using sodium azide (NaN3) as a nitriding reagent, was used for obtaining the nanopowder of aluminum nitride (AlN) from precursor that was sodium hexafluoroaluminate (Na3AlF6). The product of burning the mixture of Na3AlF6 + 3NaN3 after water rinsing consisted of micro - and nanoparticles of AlN (65%) and the residue of salt Na3AlF6 (35%). This product of SHS-Az was mixed with copper powder and pressed into a briquette of nanopowdery master alloy Cu- 4%(65%AlN+35%Na3AlF6), which was successfully introduced into aluminium melt at a temperature of 850°C. The salt Na3AlF6 in the product of combustion played a role of flux during introducing into the aluminum melt and was not included in the final composition of the composite alloy. The microstructure of the obtained cast composite aluminum alloy with the calculated composition of Al-1.2%Cu-0.035%AlN showed that the reinforcing particles of AlN of different sizes, including nanoparticles, were distributed mainly along the grain boundaries of the aluminum alloy.
11. Al- and Cu-doped BaSi2 films on Si(111) substrate by molecular beam epitaxy and evaluation of depth profiles of Al and Cu atoms
Ajmal Khan, M.; Takeishi, M.; Matsumoto, Y.; Saito, T.; Suemasu, T.
The main objective of the present work is to evaluate and compare the depth profiles of Al and Cu atoms in in-situ doped BaSi2. Furthermore, it is also desired to investigate and compare the carrier concentration of Al-doped as well as Cu-doped BaSi2 films and qualify as a potential dopant-candidate for more efficient solar cells of BaSi2. During the experiment, reactive deposition epitaxy and molecular beam epitaxy were used to develop the samples. X-ray diffraction (XRD) measurements and secondary ion mass spectroscopy (SIMS), were used to determine the structure, depth profile and composition of the already grown films. The electrical properties were characterized by Hall measurement using the van der Pauw method. In case of Al-doped BaSi2 films, it was not encouraging result due to diffusion and segregation of Al in both the surface and BaSi2/ Si interface regions. On the other hand, those phenomena were not observed for Cu-doped BaS2 films. Heavily Cu-doped BaSi2 showed n+ conductivity, differently from our prediction.
12. Wetting of TiC by Al-Cu alloys and interfacial characterization.
PubMed
Contreras, A
2007-07-01
The wetting behavior and the interfacial reactions that occurred between molten Al-Cu alloys (1, 4, 8, 20, 33, and 100 wt% Cu) and solid TiC substrates were studied by the sessile drop technique in the temperature range of 800-1130 degrees C. The effect of wetting behavior on the interfacial reaction layer was studied. All the Al-Cu alloys react with TiC at the interface forming an extensive reaction layer. The interface thickness varied with the samples, and depends on the temperature, chemical composition of the alloy and the time of the test. Wetting increases with increasing concentration of copper in the Al-Cu alloy at 800 and 900 degrees C. In contrast, at higher temperature such as 1000 degrees C wetting decreases with increasing copper content. The spreading kinetics and the work of adhesion were evaluated. The high values of activation energies indicated that spreading is not a simple viscosity controlled phenomenon but is a chemical reaction process. The spreading of the aluminum drop is observed to occur according to the formation of Al4C3, CuAl2O4, CuAl2, TiCux mainly, leading to a decreases in the contact angle. As the contact angle decreases the work of adhesion increases with increasing temperature. Al-Cu/TiC assemblies showed cohesive fracture corresponding to a strong interface. However, using pure Cu the adhesion work is poor, and the percentage of cohesion work is also too low (27-34%).
13. Large pinning forces and matching effects in YBa2Cu3O(7-δ) thin films with Ba2Y(Nb/Ta)O6 nano-precipitates.
PubMed
Opherden, Lars; Sieger, Max; Pahlke, Patrick; Hühne, Ruben; Schultz, Ludwig; Meledin, Alexander; Van Tendeloo, Gustaaf; Nast, Rainer; Holzapfel, Bernhard; Bianchetti, Marco; MacManus-Driscoll, Judith L; Hänisch, Jens
2016-02-18
The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O(7-δ) (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m(3) at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it.
14. Thermodynamic and mechanical stabilities of α- and β-Ta{sub 4}AlC{sub 3} via first-principles investigations
SciTech Connect
Thawabi, Hassan S. Duong, Thien Arróyave, Raymundo
2013-12-07
Recently, it has been predicted that Ta{sub 4}AlC{sub 3} is likely to exhibit an (α–β) polymorphic transformation at temperatures above 1873 K. However, recent X-ray diffraction and transmission electron microscopy experiments suggest on the other hand that the α phase remains stable up to temperatures close to the limit of experimental capabilities and no transition has yet been observed. While the matter has already been settled experimentally, in this work, we re-investigate the phase stability problem in Ta{sub 4}AlC{sub 3} by using first-principles methods. The study was carried out by considering both thermodynamic and mechanical stabilities of the Ta{sub 4}AlC{sub 3} polymorphs. Particularly, finite-temperature Gibbs free energies and elastic properties of the polymorphs were calculated using density functional theory. Calculation results reveal that the α phase continue to be stable even at temperatures exceeding 1875 K, which is in agreement with experimental results reported in literature.
15. Effect of delayed aging on mechanical properties of an Al-Cu-Mg alloy
SciTech Connect
Ravindranathan, S.P.; Kashyap, K.T.; Kumar, S.R.; Ramachandra, C.; Chatterji, B.
2000-02-01
The effect of delayed aging on mechanical properties is characteristically found in Al-Mg-Si alloys. Delayed aging refers to the time elapsed between solutionizing and artificial aging. Delayed aging leads to inferior properties. This effect was investigated in an Al-Cu-Mg alloy (AU2GN) of nominal composition Al-2Cu-1.5Mg-1Fe-1Ni as a function of delay. This alloy also showed a drop in mechanical properties with delay. The results are explained on the basis of Pashley's kinetic model to qualitatively explain the evolution of a coarse precipitate structure with delay. It is found that all the results of delayed aging in the Al-Cu-Mg alloys are similar to those found in Al-Mg-Si alloys.
16. Length scale of the dendritic microstructure affecting tensile properties of Al-(Ag)-(Cu) alloys
Duarte, Roberto N.; Faria, Jonas D.; Brito, Crystopher; Veríssimo, Nathalia C.; Cheung, Noé; Garcia, Amauri
2016-12-01
The dependence of tensile properties on the length scale of the dendritic morphology of Al-Cu, Al-Ag and Al-Ag-Cu alloys is experimentally investigated. These alloys were directionally solidified (DS) under a wide range of cooling rates (Ṫ), permitting extensive microstructural scales to be examined. Experimental growth laws are proposed relating the primary dendritic arm spacing, λ1 to Ṫ and tensile properties to λ1. It is shown that the most significant effect of the scale of λ1 on the tensile properties is that of the ternary alloy, which is attributed to the more homogeneous distribution of the eutectic mixture for smaller λ1 and by the combined reinforcement roles of the intermetallics present in the ternary eutectic: Al2Cu and nonequilibrium Ag3Al.
17. The effects of Cr, Co, Al, Mo and Ta on the cyclic oxidation behavior of a prototype cast Ni-base superalloy based on a 2(5) composite statistically designed experiment
NASA Technical Reports Server (NTRS)
Barrett, C. A.
1984-01-01
A series of cast Ni-base superalloys were systematically varied at selected levels of Co, Cr, Mo, Ta, and Al. The elemental levels varied were Mo, 0 to 4 percent; Cr, 6 to 18 percent; Co, 0 to 20 percent, Ta, 0 to 8 percent; and Al, 3.25 to 6.25 percent. The cyclic oxidation resistance was determined from specific weight change data as a function of time for 1 hr cycles in static air at 1100 C. The significant terms in decreasing order of their importance were Al, Ta, Cr2, Al-Cr, Cr-Co, Co2, Al-Mo, Cr-Mo, Al-Al, and Mo-Ta. The Al term alone accounted for close to 82 percent of the explained variability. The estimating equation showed that the Al level was the most important and should be at its 6.25 wt % maximum value. The Mo and Ta levels should also be at their maximum 4 and 8 wt % respectively. The cobalt composition should be as low as possible, i.e., 0 wt%. The Cr level optimum varies depending on the other 4 levels. The X-ray diffaction results indicate the most protective scales are alumina/aluminate spinel stabilizized with a tri-rutile oxide high in Ta and Mo.
18. Synthesis and analysis of nanocrystalline β1-Cu3Al and β2-NiAl intermetallic-reinforced aluminum matrix composite by high energy ball milling
Nguyen, Hong-Hai; Nguyen, Minh-Thuyet; Kim, Won Joo; Kim, Jin-Chun
2017-01-01
Nanocrystalline β1-Cu3Al and β2-NiAl intermetallic compounds were in-situ reinforced in the aluminum matrix with the atomic composition of Al67Cu20Ni13 by the mechanical alloying of elemental powders. Both β1-Cu3Al, β2-NiAl phases that can be only co-synthesized in Cu base alloys have been obtained after 15h milling in this study. The phase evolution during milling process was investigated by X-ray diffraction. The β1-Cu3Al, β2-NiAl phases were metastable with further milling time up to 40 h. Specially, unreacted Al matrix has been totally transformed to amorphous state in the final powder. A remarkable crystalline size of 6.5 nm was reached after 15 h milling time. Thermal stability of the milled powder was also studied by differential thermal analysis. It is shown that β1-Cu3Al, β2-NiAl phases were stable up to higher than 550 °C. Moreover, the inter-diffusion between Al matrix and Cu3Al within the temperature range of 620-740 °C led to the formation of superstructure ζ1-Al3Cu4 phase.
19. First-principles study of Be doped CuAlS2 for p-type transparent conductive materials
Huang, Dan; Zhao, Yu-Jun; Tian, Ren-Yu; Chen, Di-Hu; Nie, Jian-Jun; Cai, Xin-Hua; Yao, Chun-Mei
2011-06-01
CuAlS2 has attracted much attention recently as a p-type transparent conductive material. In this paper, we investigate the site preference of substitutional Be in CuAlS2 and the transition level of BeAl using the first-principles calculation. We find that Be would be doped effectively at Al sites in CuAlS2 as a good p-type dopant. In addition, we speculate that Be-Mg or Be-Zn codoped CuAlS2 could have a mobility enhancement and thus a good p-type conductivity due to low lattice distortion.
20. Effect of hydrogen on Al2O3/Cu interfacial structure and adhesion
Wang, Xiao-Gang; Smith, John R.; Scheffler, Matthias
2002-08-01
We have carried out an ab initio investigation of the effect of hydrogen on the Al2O3/Cu interface. H on the Al2O3 surface can play a bridging role in the formation of the interface. The interfacial OH bond is stable in the presence of two atomic layers of Cu. In contrast, an Al monolayer would dissociate the surface OH bond. For thicker Cu, one-third of a monolayer of H remains stable in the interface, lowering the work of separation by 2.3 J/m2. The interfacial work of separation remains larger than that of bulk Cu, however. These results are consistent with available experimental data.
1. Cyclic Oxidation Behavior of CuCrAl Cold-Sprayed Coatings for Reusable Launch Vehicles
NASA Technical Reports Server (NTRS)
Raj, Sai; Karthikeyan, J.
2009-01-01
The next generation of reusable launch vehicles is likely to use GRCop-84 [Cu-8(at.%)Cr-4%Nb] copper alloy combustion liners. The application of protective coatings on GRCop-84 liners can minimize or eliminate many of the environmental problems experienced by uncoated liners and significantly extend their operational lives and lower operational cost. A newly developed Cu- 23 (wt.%) Cr-5% Al (CuCrAl) coating, shown to resist hydrogen attack and oxidation in an as-cast form, is currently being considered as a protective coating for GRCop-84. The coating was deposited on GRCop-84 substrates by the cold spray deposition technique, where the CuCrAl was procured as gas-atomized powders. Cyclic oxidation tests were conducted between 773 and 1,073 K to characterize the coated substrates.
2. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys
Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.
2016-12-01
Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion.
3. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys
PubMed Central
Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.
2016-01-01
Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion. PMID:28000750
4. Microstructure evolution and strain localization in Cu and Cu-8Al single crystals subjected to channel-die compression.
PubMed
Lewandowska, Małgorzata; Swiatnicki, Wiesław; Piatkowski, Andrzej; Jasienski, Zdzisław
2006-09-01
Single crystals of pure Cu and Cu-8%Al with two initial orientations, {112}111 and {112}110, were subjected to monotonic compression in channel-die at room temperature (293 K). The dislocation microstructure and local crystallography were investigated by transmission electron microscopy after different amounts of deformation. Various factors, such as initial single crystal orientation, chemical composition and amount of plastic deformation, were analysed in order to determine their influence on the microstructure evolution, local orientation variations and strain localization phenomena.
5. Microstructural Observations in a Cast Al-Si-Cu/TiC Composite
Karantzalis, A. E.; Lekatou, A.; Georgatis, E.; Poulas, V.; Mavros, H.
2010-06-01
A 3-5 vol.% TiC particulate Al-Si-Cu composite was prepared by diluting Al/20 vol.% TiC composite in an Al-7Si-4Cu alloy matrix. TiC particle distribution consists of isolated and clustered particles which are both located at the primary-α grain boundaries and at the areas of the last solidified liquid. Particle pushing by the solidification front is responsible for the final particle location. The solidified microstructure consists of primary and intermetallic phases formed by a sequence of possible eutectic reactions. No evidence of TiC particle degradation was observed.
6. AlCu alloy films prepared by the thermal diffusion technique
SciTech Connect
Oliva, A.I.; Corona, J.E.; Sosa, V.
2010-07-15
100-nm thick films of Al{sub 1-x}Cu{sub x} alloys were prepared on glass substrates by thermal diffusion technique. The Cu atomic concentration was varied from 10% to 90%. Alloys were prepared at different temperatures into a vacuum oven with Argon atmosphere. Two thermal processes were used: i) heating the film at 400 deg. C in a single step, and ii) heating the films in sequential steps at 100, 200, 300 and 400 deg. C. Morphology, electrical resistivity, and crystalline orientation of the alloys were studied. The electrical resistivity and surface roughness of the alloys were found to depend strongly on the atomic composition and the diffusion temperature. However, we did not find differences between samples prepared under the two thermal processes. Alloys prepared with x = 0.6 and x = 0.1-0.3 as Cu at concentration exhibited values on electrical resistivity and surface roughness lower than pure Al. Different phases of the Al{sub 1} {sub -} {sub x}Cu{sub x} films were observed as a function of Cu concentration showing a good agreement with the AlCu phase diagram.
7. Effect of Ag Addition on the Electrochemical Performance of Cu10Al in Artificial Saliva
PubMed Central
2016-01-01
In this work we proposed to evaluate the corrosion resistance of four different alloys by electrochemical techniques, a binary alloy Cu10Al, and three ternary alloys Cu10Al-xAg (x = 5, 10, and 15 wt.%) to be used like biomaterials in dental application. Biomaterials proposed were tested in artificial saliva at 37°C for 48 h. In addition, pure metals Cu, Al, Ag, and Ti as reference materials were evaluated. In general the short time tests indicated that the Ag addition increases the corrosion resistance and reduces the extent of localized attack of the binary alloy. Moreover, tests for 48 hours showed that the Ag addition increases the stability of the passive layer, thereby reducing the corrosion rate of the binary alloy. SEM analysis showed that Cu10Al alloy was preferably corroded by grain boundaries, and the Ag addition modified the form of attack of the binary alloy. Cu-rich phases reacted with SCN− anions forming a film of CuSCN, and the Ag-rich phase is prone to react with SCN− anions forming AgSCN. Thus, binary and ternary alloys are susceptible to tarnish in the presence of thiocyanate ions. PMID:27660601
8. X-ray emission study of ion beam mixed Cu/Al films on polyimide
SciTech Connect
Kurmaev, E.Z.; Zatsepin, D.A.; Winarski, R.P.; Stadler, S.; Ederer, D.L.; Moewes, A.; Fedorenko, V.V.; Shamin, S.N.; Galakhov, V.R.; Chang, G.S.; Whang, C.N.
1999-03-01
Cu (40 nm)/Al/polyimide/Si was mixed with 80 keV Ar{sup +} and N{sub 2}{sup +} from 5.0{times}10{sup 15} to 15{times}10{sup 15} ions/cm{sup 2}. Ultrasoft x-ray emission valence spectra (XES) of Cu, C, N and O excited by electron and photon radiation were used for study of chemical reactions in Cu/Al/PI/Si and PI/Si systems induced by ion beam mixing in dependence of type of ions and dose. It is found that ion beam mixing changes the chemical state of Cu atoms with respect to that of pure metal. These changes depend on the dose of ion beam bombardment and type of ions and are attributed to a formation of CuAl{sub 2}O{sub 4} interfacial layer, which can be responsible for enhanced interfacial adhesion strength. On the other hand, it is shown that the shape of C {ital K}{alpha}, N {ital K}{alpha} and O {ital K}{alpha} XES of ion beam mixed polyimide layer (PI/Si) is modified with ion bombardment. This means that the ion-beam mixing process is able to break the bonding of constituent atoms of irradiated PI layers and can induce the formation of chemically bonded complexes linking atoms in the Cu, Al and PI layers.{copyright} {ital 1999 American Vacuum Society.}
9. Crystallization kinetics of rapidly quenched Cu50Zr50 and Cu46Zr46Al8 glass-forming alloys
Kulikova, T. V.; Ryltseva, A. A.; Bykov, V. A.; Estemirova, S. Kh; Shuhyaev, K. Yu
2017-01-01
We studied the crystallization processes, the structure and thermal properties of amorphous alloys Cu50Zr50 and Cu46Zr46Al8 in a wide temperature range. Comparative study of the crystallization kinetics of these amorphous alloys was carried out for the first time using multivariate non-linear regression. It was found that mechanisms of the crystallization of studied metallic glasses are substantially different. The binary alloy is crystallized by branched reaction complex in four steps. For the ternary system was proposed two-step kinetic model of the crystallization process with consecutive reactions. The values of the total energy of activation for each crystallization stage reach to Cu50Zr50: E1 (345.2 kJ/mol); E2 (307.9 kJ/mol), E3 (281.1 kJ/mol), E4 (259.51 kJ/mol) and Cu46Zr46Al8: E1 (350.7 kJ/mol); E2 (150.4 kJ/mol).
10. Assessment of Post-eutectic Reactions in Multicomponent Al-Si Foundry Alloys Containing Cu, Mg, and Fe
Javidani, Mousa; Larouche, Daniel; Grant Chen, X.
2015-07-01
Post-eutectic reactions occurring in Al-Si hypoeutectic alloys containing different proportions of Cu, Mg, and Fe were thoroughly investigated in the current study. As-cast microstructures were initially studied by optical and electron microscopy to investigate the microconstituents of each alloy. Differential scanning calorimetry (DSC) was then used to examine the phase transformations occurring during the heating and cooling processes. Thermodynamic calculations were carried out to assess the phase formation under equilibrium and in nonequilibrium conditions. The Q-Al5Cu2Mg8Si6 phase was predicted to precipitate from the liquid phase, either at the same temperature or earlier than the θ-Al2Cu phase depending on the Cu content of the alloy. The AlCuFe-intermetallic, which was hardly observed in the as-cast microstructure, significantly increased after the solution heat treatment in the alloys containing high Cu and Fe contents following a solid-state transformation of the β-Al5FeSi phase. After the solution heat treatment, the AlCuFe-intermetallics were mostly identified with the stoichiometry of the Al7Cu2Fe phase. Thermodynamic calculations and microstructure analysis helped in determining the DSC peak corresponding to the melting temperature of the N-Al7Cu2Fe phase. The effect of Cu content on the formation temperature of π-Al8Mg3FeSi6 is also discussed.
11. Microstructural changes to AlCu6Ni1 alloy after prolonged annealing at elevated temperature.
PubMed
Wierzbińska, M; Sieniawski, J
2010-03-01
This work presents results of microstructure examination of AlCu(6)Ni(1) aluminium alloy. The commercial AlCu(4)Ni(2)Mg(2) (M-309) alloy is widely used for elements of aircraft and automotive engines. Modification its chemical composition was aimed at improving the stability of mechanical properties of the alloy subjected to long-term exposure to high temperature. The alloy after standard T6 heat treatment (solution heat treated at 818 K/10 h/water quenched followed by ageing at 498 K/8 h/air cooled) was annealed for 150 h at elevated temperature of 573 K corresponding to the maximum value at which structural elements of jet piston engines made of aluminium alloys operate. It was found that applied heat treatment caused an increasing in the particles of hardening phase (theta'-Al(2)Cu) size. The significant growth of the length of theta'-Al(2)Cu precipitations was observed in particularly. Nevertheless, it did not strongly result in change of its shape - the 'crystallites' and 'rods' were still characteristic of hardening phase morphology. The phenomena of the growth of theta'-Al(2)Cu precipitates caused decreasing the mechanical properties of the alloy, what is the subject of further investigations by the authors.
12. Electroless Cu Plating on Anodized Al Substrate for High Power LED.
PubMed
Rha, Sa-Kyun; Lee, Youn-Seoung
2015-03-01
Area-selective copper deposition on screen printed Ag pattern/anodized Al/Al substrate was attempted using a neutral electroless plating processes for printed circuit boards (PCBs), according to a range of variation of pH 6.5-pH 8 at 70 °C. The utilized basic electroless solution consisted of copper(II) sulfate pentahydrate, sodium phosphinate monohydrate, sodium citrate tribasic dihydrate, ammonium chloride, and nickel(II) sulfate hexahydrate. The pH of the copper plating solutions was adjusted from pH 6.5 to pH 8 using NH4OH. Using electroless plating in pH 6.5 and pH 7 baths, surface damage to the anodized Al layer hardly occurred; the structure of the plated Cu-rich films was a typical fcc-Cu, but a small Ni component was co-deposited. In electroless plating at pH 8, the surface of the anodized Al layer was damaged and the Cu film was composed of a lot of Ni and P which were co-deposited with Cu. Finally, in a pH 7 bath, we can make a selectively electroless plated Cu film on a PCB without any lithography and without surface damage to the anodized Al layer.
13. Enhanced 77 K vortex-pinning in Y Ba2Cu3O7-x films with Ba2Y TaO6 and mixed Ba2Y TaO6 + Ba2Y NbO6 nano-columnar inclusions with irreversibility field to 11 T
Rizzo, F.; Augieri, A.; Angrisani Armenio, A.; Galluzzi, V.; Mancini, A.; Pinto, V.; Rufoloni, A.; Vannozzi, A.; Bianchetti, M.; Kursumovic, A.; MacManus-Driscoll, J. L.; Meledin, A.; Van Tendeloo, G.; Celentano, G.
2016-06-01
Pulsed laser deposited thin Y Ba2Cu3O7-x (YBCO) films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO) were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO) additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO) and 11 T (YBCO-BYNTO), representing the highest ever achieved values in YBCO films.
14. High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy
NASA Technical Reports Server (NTRS)
Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.
1991-01-01
Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.
15. Surface tension of liquid Al-Cu and wetting at the Cu/Sapphire solid-liquid interface
Schmitz, J.; Brillo, J.; Egry, I.
2014-02-01
For the study of the interaction of a liquid alloy with differently oriented single crystalline sapphire surfaces precise surface tension data of the liquid are fundamental. We measured the surface tension of liquid Al-Cu contactlessly on electromagnetically levitated samples using the oscillating drop technique. Data were obtained for samples covering the entire range of composition and in a broad temperature range. The surface tensions can be described as linear functions of temperature with negative slopes. Moreover, they decrease monotonically with an increase of aluminium concentration. The observed behaviour with respect to both temperature and concentration is in agreement with a thermodynamic model calculation using the regular solution approximation. Surface tensions were used to calculate interfacial energies from the contact angles of liquid Cu droplets, deposited on the C(0001), A(11-20), R(1-102) surfaces of an α-Al2O3 substrate. The contact angles were measured by means of the sessile drop method at 1380 K. In the Cu/α-Al2O3 system, no anisotropy is evident neither for the contact angles nor for the interfacial energies of different surfaces. The work of adhesion of this system is isotropic, too.
16. S = 1/2 Square-Lattice Antiferromagnets: (CuX)LaB_2O_7 and (CuCl)A_2B_3O10 (X = Cl, Br; A = Ca, Sr; B = Nb, Ta)
Kageyama, H.; Kitano, T.; Nakanishi, R.; Yasuda, J.; Oba, N.; Baba, Y.; Nishi, M.; Ueda, Y.; Ajiro, Y.; Yoshimura, K.
A series of magnetic compounds with the formula (CuX)LaB_2O_7 and (CuCl)A_2B_3O10 (X = Cl, Br; A = Ca, Sr; B = Nb, Ta) have been prepared through a low-temperature topochemical route starting from nonmagnetic double- (n = 2) and triple- (n = 3) layered perovskites, respectively. The magnetic susceptibility of these compounds typically exhibits a broad maximum at low temperatures, characteristic of low-dimensional antiferromagnetic compounds. However, depending on the choice of the parameters, X, A, B and n, physical quantities such as the Weiss temperature and the temperature at a maximum susceptibility vary to a great extent, which enables us to study the phase diagram of the S = 1/2 frustrated square-lattice antiferromagnets (the so-called J_1-J_2 model). In particular, (CuCl)LaNb_2O_7, possibly having a ferromagnetic J_1 and an antiferromagnetic J_2, shows a spin-liquid behavior with the spin gap of 27 K.
17. Chemical Trend of Superconducting Critical Temperatures in Hole-Doped CuBO2, CuAlO2, CuGaO2, and CuInO2
Nakanishi, Akitaka; Katayama-Yoshida, Hiroshi; Ishikawa, Takahiro; Shimizu, Katsuya
2016-09-01
We calculated the superconducting critical temperature (Tc) for hole-doped CuXO2 (X = B, Al, Ga, and In) compounds using first-principles calculations based on rigid band model. The compounds with X = Al, Ga, and In have delafosite-type structures and take maximum Tc values at 0.2-0.3 with respect to the number of holes (Nh) in the unit-cell: 50 K for CuAlO2, 10 K for CuGaO2, and 1 K for CuInO2. The decrease of Tc for this change in X is involved by covalency reduction and lattice softening associated with the increase of ionic mass and radius. For CuBO2 which is a lighter compound than CuAlO2, the delafosite structure is unstable and a body-centered tetragonal structure emerges as the most stable structure. As the results, the electron-phonon interaction is decreased and Tc is lower by approximately 43 K than that of CuAlO2 at the hole-doping conditions of Nh = 0.2-0.3.
18. Real-time x-ray microbeam characterization of electromigration effects in Al(Cu) wires
SciTech Connect
Wang, P.-C.; Noyan, I. C.; Kaldor, S. K.; Jordan-Sweet, J. L.; Liniger, E. G.; Hu, C.-K.
2001-04-30
We report real-time, in situ x-ray microbeam measurements of electromigration-induced Cu redistribution, and the concurrent local stress variation in Al(Cu) wires. The data, which were obtained by combining x-ray microtopography with energy-dispersive fluorescence analysis, encompass both the early and late stages of electromigration as well as the postrelaxation stage at high temperature with the current turned off. We observe that both Cu concentration and stress values show unexpected local variations that may reflect the effect of local configuration such as film--substrate interface integrity or microstructure.
19. Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction
Tao, B. S.; Li, D. L.; Yuan, Z. H.; Liu, H. F.; Ali, S. S.; Feng, J. F.; Wei, H. X.; Han, X. F.; Liu, Y.; Zhao, Y. G.; Zhang, Q.; Guo, Z. B.; Zhang, X. X.
2014-09-01
Magnetic properties of Co40Fe40B20 (CoFeB) thin films sandwiched between Ta and MgAl2O4 layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4 structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki = 1.22 erg/cm2, which further increases to 1.30 erg/cm2 after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0 nm, while that for top CoFeB layer is between 0.8 and 1.4 nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.
20. Joule-Heating-Induced Damage in Cu-Al Wedge Bonds Under Current Stressing
Yang, Tsung-Han; Lin, Yu-Min; Ouyang, Fan-Yi
2014-01-01
Copper wires are increasingly used to replace gold wires in wire-bonding technology owing to their better electrical properties and lower cost. However, not many studies have been conducted on electromigration-induced failure of Cu wedge bonds on Al metallization. In this study, we investigated the failure mechanism of Cu-Al wedge bonds under high current stressing from 4 × 104 A/cm2 to 1 × 105 A/cm2 at ambient temperature of 175°C. The resistance evolution of samples during current stressing and the microstructure of the joint interface between the Cu wire and Al-Si bond pad were examined. The results showed that abnormal crack formation accompanying significant intermetallic compound growth was observed at the second joint of the samples, regardless of the direction of electric current for both current densities of 4 × 104 A/cm2 and 8 × 104 A/cm2. We propose that this abnormal crack formation at the second joint is mainly due to the higher temperature induced by the greater Joule heating at the second joint for the same current stressing, because of its smaller bonded area compared with the first joint. The corresponding fluxes induced by the electric current and chemical potential difference between Cu and Al were calculated and compared to explain the failure mechanism. For current density of 1 × 105 A/cm2, the Cu wire melted within 0.5 h owing to serious Joule heating.
1. Mechanism of resistive switching in Cu/AlOx/W nonvolatile memory structures
Sleiman, A.; Sayers, P. W.; Mabrook, M. F.
2013-04-01
The mechanism for resistive switching in aluminum oxide (AlOx) based electrochemical metallization memory cells is presented. Copper/AlOx/tungsten (Cu/AlOx/W) cells show reproducible resistive switching with an ON/OFF ratio of about 5 × 102 at a reading voltage of 0.1 V and reliable retention characteristics. Resistive switching occurs due to the formation and rupture of a Cu filament between the active electrode (Cu) and the counter electrode (W). The conduction of the devices was explained through back-to-back Schottky contacts in the OFF state, while it exhibits ohmic behavior in the ON state. Thermionic emission model was used to calculate the barrier heights of the Schottky contacts. The rupture of the Cu filament proved to occur at the weakest point of the filament inside the AlOx. Using Ohms Law, the slope of the linear I-V characteristics in the ON state was used to extract the Cu filament resistance and its diameter was estimated to be between 6 and 23 nm.
2. Corrosion behaviors of Al-Si-Cu-based filler metals and 6061-T6 brazements
Su, T. L.; Wang, S. S.; Tsao, L. C.; Chang, S. Y.; Chuang, T. H.; Yeh, M. S.
2002-04-01
The corrosion behaviors of a series of Al-Si-Cu-based filler metals and the 6061-T6 butt joints brazed with these filler metals are evaluated by polarization tests and immersion tests in a 3.5% NaCl aqueous solution. For comparison, a traditional Al-12Si filler metal is also employed. The results indicate that the Al-Si-Cu-based filler metals before brazing possess much higher corrosion current densities and pitting tendencies than the Al-12Si filler metal. However, brazing of the 6061-T6 alloy with an Al-12Si filler metal produces a wider butt joint, which, in this case, creates a more extensive corrosion region. Severe galvanic corrosion occurs at the 6061-T6 joints when brazed with Al-Si-Cu-based filler metals. However, in the case of the 6061-T6/Al-12Si brazements, selective corrosion of the Al-12Si eutectic phase can be observed. The bonding strengths of the 6061-T6 butt joints brazed with various filler metals are also measured before and after the immersion tests.
3. Growth of intermetallic phases in Al/Cu composites at various annealing temperatures during the ARB process
Hsieh, Chih-Chun; Shi, Ming-Shou; Wu, Weite
2012-02-01
The purpose of this study is to discuss the effect of annealing temperatures on growth of intermetallic phases in Al/Cu composites during the accumulative roll bonding (ARB) process. Pure Al (AA1100) and pure Cu (C11000) were stacked into layered structures at 8 cycles as annealed at 300 °C and 400 °C using the ARB technique. Microstructural results indicate that the necking of layered structures occur after 300 °C annealing. Intermetallic phases grow and form a smashed morphology of Al and Cu when annealed at 400 °C. From the XRD and EDS analysis results, the intermetallic phases of Al2Cu (θ) and Al4Cu9 (γ2) formed over 6 cycles and the AlCu (η2) precipitated at 8 cycles after 300 °C annealing. Three phases (Al2Cu (θ), Al4Cu9 (γ2), and AlCu (η2)) were formed over 2 cycles after 400 °C annealing.
4. Microstructure and Mechanical Properties of Laser-Welded Joints of Ti-22Al-25Nb/TA15 Dissimilar Titanium Alloys
Li, Dalong; Hu, Shengsun; Shen, Junqi; Zhang, Hao; Bu, Xianzheng
2016-05-01
Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α' phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal.
5. Microstructure properties and microhardness of rapidly solidified Al64Cu20Fe12Si4 quasicrystal alloy
Karaköse, Ercan; Keskin, Mustafa
2012-04-01
This paper presents differences in the microstructure and microhardness properties of conventional casting (ingot) and rapidly solidified Al64Cu20Fe12Si4 quasicrystal (QC) alloys. The phases present in the Al64Cu20Fe12Si4 ingot alloy were determined to be icosahedral quasicrystalline (IQC) Ψ-Al65Cu20Fe15, cubic β-AlFe, tetragonal θ-Al2Cu, and monoclinic λ-A13Fe4 phases, whereas only IQC Ψ-Al65Cu20Fe15 and cubic β-AlFe phases were identified in the rapidly solidified alloy. The microhardness value of the melt spun alloy was measured to be approximately 790 kg/mm2. Microhardness increases with increasing solidification rates.
6. Resistance to Fracture, Fatigue and Stress-Corrosion of Al-Cu-Li-Zr Alloys
DTIC Science & Technology
2007-11-02
Zr alloyý, 4 Heat treatment and hot rolling schedules fur 66 the Al-Cu-Li-Zr alloys 5 Laue transmission analysis of Al-Cu-Li-Zr alloys 67 6 X-ray...ratio, there appears to be an increase in amount of matrix 6 ’ as well as grain boundary precipitates ( 6 , T-phase) (? 4 ). As a result, there is a...containing 6 ’ precipitates that enhance slip planarity and certain titanium alloys (e.g. alloys with acicular astructure), will be expected to have a
7. Equation of State of an AlCoCrCuFeNi High-Entropy Alloy
Li, Gong; Xiao, Daihong; Yu, Pengfei; Zhang, Lijun; Liaw, Peter K.; Li, Yanchun; Liu, Riping
2015-08-01
The pressure-volume (P-V) relationship of the AlCoCrCuFeNi high-entropy alloy (HEA) at room temperature has been studied using in situ high-pressure energy-dispersive x-ray diffraction with synchrotron radiation at high pressures. The equation of state of the AlCoCrCuFeNi HEA is determined by the calculation of the radial distribution function. The experimental results indicate that the HEA keeps a stable face-centered-cubic + body-centered-cubic structure in the experimental pressure range from 0 GPa to 24 GPa.
8. Characterization of Al-Cu-Mg-Ag Alloy RX226-T8 Plate
NASA Technical Reports Server (NTRS)
Lach, Cynthia L.; Domack, Marcia S.
2003-01-01
Aluminum-copper-magnesium-silver (Al-Cu-Mg-Ag) alloys that were developed for thermal stability also offer attractive ambient temperature strength-toughness combinations, and therefore, can be considered for a broad range of airframe structural applications. The current study evaluated Al-Cu-Mg-Ag alloy RX226-T8 in plate gages and compared performance with sheet gage alloys of similar composition. Uniaxial tensile properties, plane strain initiation fracture toughness, and plane stress tearing resistance of RX226-T8 were examined at ambient temperature as a function of orientation and thickness location in the plate. Properties were measured near the surface and at the mid-plane of the plate. Tensile strengths were essentially isotropic, with variations in yield and ultimate tensile strengths of less than 2% as a function of orientation and through-thickness location. However, ductility varied by more than 15% with orientation. Fracture toughness was generally higher at the mid-plane and greater for the L-T orientation, although the differences were small near the surface of the plate. Metallurgical analysis indicated that the microstructure was primarily recrystallized with weak texture and was uniform through the plate with the exception of a fine-grained layer near the surface of the plate. Scanning electron microscope analysis revealed Al-Cu-Mg second phase particles which varied in composition and were primarily located on grain boundaries parallel to the rolling direction. Fractography of toughness specimens for both plate locations and orientations revealed that fracture occurred predominantly by transgranular microvoid coalescence. Introduction High-strength, low-density Al-Cu-Mg-Ag alloys were initially developed to replace conventional 2000 (Al-Cu-Mg) and 7000 (Al-Zn-Cu-Mg) series aluminum alloys for aircraft structural applications [1]. During the High Speed Civil Transport (HSCT) program, improvements in thermal stability were demonstrated for candidate
9. Re-investigation of phase equilibria in the system Al-Cu and structural analysis of the high-temperature phase η1-Al1-δCu.
PubMed
Ponweiser, Norbert; Lengauer, Christian L; Richter, Klaus W
2011-11-01
The phase equilibria and reaction temperatures in the system Al-Cu were re-investigated by a combination of optical microscopy, powder X-ray diffraction (XRD) at ambient and elevated temperature, differential thermal analysis (DTA) and scanning electron microscopy (SEM). A full description of the phase diagram is given. The phase equilibria and invariant reactions in the Cu-poor part of the phase diagram could be confirmed. The Cu-rich part shows some differences in phase equilibria and invariant reactions compared to the known phase diagram. A two phase field was found between the high temperature phase η1 and the low temperature phase η2 thus indicating a first order transition. In the ζ1/ζ2 region of the phase diagram recent findings on the thermal stability could be widely confirmed. Contrary to previous results, the two phase field between δ and γ1 is very narrow. The results of the current work indicate the absence of the high temperature β0 phase as well as the absence of a two phase field between γ1 and γ0 suggesting a higher order transition between γ1 and γ0. The structure of γ0 (I-43m, Cu5Zn8-type) was confirmed by means of high-temperature XRD. Powder XRD was also used to determine the structure of the high temperature phase η1-Al1-δCu. The phase is orthorhombic (space group Cmmm) and the lattice parameters are a = 4.1450(1) Å, b = 12.3004(4) Å and c = 8.720(1) Å; atomic coordinates are given.
10. Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy
SciTech Connect
Asghar, Z.
2014-02-15
The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an α-Al matrix. The strength at room temperature and at 300°C is studied as a function of solution treatment time at 490°C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300°C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300°C. - Highlights: • The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. • An imaging analysis procedure to segment phases with similar contrasts is presented. • 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. • AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.
11. Thermal Analysis of the Effect of Oxygen Contamination on Undercooling of Zr-Al-Ni-Cu, Cu-Zr-Ti, and Cu-Ni-Zr-Ti Metallic Glasses (Preprint)
DTIC Science & Technology
2009-04-01
been done on systems other than Zr65Al7.5(Cu17.5Ni10). Zr55Al10(Cu30Ni5) was found to be less sensitive to oxygen content than Zr65Al7.5(Cu17.5Ni10...Zr11Ti34 by arc-melting each of the pure elements under a titanium - gettered atmosphere. Starting materials used were: Al pellets, 99.999%; Cu shot...produce 2-6 g alloyed ingots of each composition. Each ingot was flipped typically 4-5 times in a titanium -gettered, high-purity argon atmosphere
12. Dissolution of Cu/Mg Bearing Intermetallics in Al-Si Foundry Alloys
Javidani, Mousa; Larouche, Daniel; Grant Chen, X.
2016-10-01
Evolutions of the Cu/Mg bearing intermetallics were thoroughly investigated in four Al-Si hypoeutectic alloys containing various Cu (1 and 1.6 wt pct) and Mg (0.4 and 0.8 wt pct) contents. The area fractions of Cu/Mg bearing phases before and after solution heat treatment (SHT) were quantified to evaluate the solubility/stability of the phases. Two Mg-bearing intermetallics (Q-Al5Cu2Mg8Si6, π-Al8FeMg3Si6) which appear as gray color under optical microscope were discriminated by the developed etchant. Moreover, the concentrations of the elements (Cu, Mg, and Si) in α-Al were analyzed. The results illustrated that in the alloys containing ~0.4 pct Mg, Q-Al5Cu2Mg8Si6 phase was dissolved after 6 hours of SHT at 778 K (505 °C); but containing in the alloys ~0.8 pct Mg, it was insoluble/ partially soluble. Furthermore, after SHT at 778 K (505 °C), Mg2Si was partially substituted by Q-phase. Applying a two-step SHT [6 hours@778 K (505 °C) + 8 hours@798 K (525 °C)] in the alloys containing ~0.4 pct Mg helped to further dissolve the remaining Mg bearing intermetallics and further modified the microstructure, but in the alloys containing ~0.8 pct Mg, it caused partial melting of Q-phase. Thermodynamic calculations were carried out to assess the phase formation in equilibrium and in non-equilibrium conditions. There was an excellent agreement between the experimental results and the predicted results.
13. Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.
PubMed
Colić, Miodrag; Rudolf, Rebeka; Stamenković, Dragoslav; Anzel, Ivan; Vucević, Dragana; Jenko, Monika; Lazić, Vojkan; Lojen, Gorazd
2010-01-01
Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but their biomedical application is still limited. The aim of this work was to compare the microstructure, corrosion and cytotoxicity in vitro of a Cu-Al-Ni SMA. Rapidly solidified (RS) thin ribbons, manufactured via melt spinning, were used for the tests. The control alloy was a permanent mould casting of the same composition, but without shape memory effect. The results show that RS ribbons are significantly more resistant to corrosion compared with the control alloy, as judged by the lesser release of Cu and Ni into the conditioning medium. These results correlate with the finding that RS ribbons were not cytotoxic to L929 mouse fibroblasts and rat thymocytes. In addition, the RS ribbon conditioning medium inhibited cellular proliferation and IL-2 production by activated rat splenocytes to a much lesser extent. The inhibitory effects were almost completely abolished by conditioning the RS ribbons in culture medium for 4 weeks. Microstructural analysis showed that RS ribbons are martensitic, with boron particles as a minor phase. In contrast, the control Cu-Al-Ni alloy had a complex multiphase microstructure. Examination of the alloy surfaces after conditioning by energy dispersive X-ray and Auger electron spectroscopy showed the formation of Cu and Al oxide layers and confirmed that the metals in RS ribbons are less susceptible to oxidation and corrosion compared with the control alloy. In conclusion, these results suggest that rapid solidification significantly improves the corrosion stability and biocompatibility in vitro of Cu-Al-Ni SMA ribbons.
14. Influence of Al2O3 sol concentration on the microstructure and mechanical properties of Cu-Al2O3 composite coatings
Wei, Xiaojin; Yang, Zhendi; Tang, Ying; Gao, Wei
2015-03-01
Copper (Cu) is widely used as electrical conducting and contacting material. However, Cu is soft and does not have good mechanical properties. In order to improve the hardness and wear resistance of Cu, sol-enhanced Cu-Al2O3 nanocomposite coatings were electroplated by adding a transparent Al oxide (Al2O3) sol into the traditional electroplating Cu solution. It was found that the microstructure and mechanical properties of the nanocomposite coatings were largely influenced by the Al2O3 sol concentration. The results show that the Al2O3 nanoparticle reinforced the composite coatings, resulting in significantly improved hardness and wear resistance in comparison with the pure Cu coatings. The coating prepared at the sol concentration of 3.93 mol/L had the best microhardness and wear resistance. The microhardness has been improved by 20% from 145.5 HV (Vickers hardness number) of pure Cu coating to 173.3 HV of Cu-Al2O3 composite coatings. The wear resistance was also improved by 84%, with the wear volume loss dropped from 3.2 × 10-3 mm3 of Cu coating to 0.52 × 10-3 mm3 of composite coatings. Adding excessive sol to the electrolyte deteriorated the properties.
15. Numerical investigation on thermal properties at Cu-Al interface in micro/nano manufacturing
Zhang, Liqiang; Yang, Ping; Chen, Min; Liao, Ningbo
2012-02-01
A hybrid model by integrating TTM (two-temperature model) and MD (molecular dynamics) is proposed to investigate the properties on interface of dissimilar materials under thermal flux conditions. This model can describe the electron phonon coupling and phonon scattering at the interface of different metals easily. By comparing the Cu-Cu interface and Cu-Al interface, the atoms of the Cu-Cu interface at different sides tend to move together; while, the atoms displacements of Cu and Al are opposite along the interface, which may cause stress and voids at the interface. Moreover, the propagation mechanisms of nanocracks and the corresponding change of temperature distribution and thermal flux are investigated. The results show that the interfaces of dissimilar materials are prone to crack initiations, leading to delaminations because of the high temperature. All these are useful for understanding the deformation and failure of the interfaces structures. It implies a potential method for design and analysis of interface structure in micro/nano manufacturing.
16. Solid Collection Efforts: Ta Collimator Evaluation
SciTech Connect
Gostic, J M
2011-11-21
Ta collimator sets that were part of the gated x-ray detector diagnostic (GXD) at NIF were analyzed for debris distribution and damage in 2011. These disks (ranging in thickness from 250 to 750 {mu}m) were fielded approximately 10 cm from target chamber center (TCC) on various symcap, THD and re-emit shots. The nose cone holder and forward Ta collimator (facing target chamber center, TCC) from all shots show evidence of surface melt. Non-destructive analysis techniques such as optical microscopy, surface profilometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray fluorescence (XRF) were used to determine debris composition and degree of deformation associated with each Ta disk. Molten debris from the stainless steel nose cone contaminated the surface of the collimators along with other debris associated with the target assembly (Al, Si, Cu, Au and In). Surface elemental analysis of the forward collimator Ta disks indicates that Au hohlraum debris is less concentrated on these samples versus those fielded 50 cm from TCC in the wedge range filter (WRF) assembly. It is possible that the Au is distributed below or within the stainless steel melt layer covering the disk, as most of the foreign debris is captured in the melted coating. The other disks (fielded directly behind the forward collimator in a sandwiched configuration) have visible forms of deformation and warping. The degree of warping increases as the shock wave penetrates the assembly with the most damage sustained on the back collimator. In terms of developing a solid collection capability, the collimator analyses suggests that close proximity may cause more interference with capsule debris collection and more damage to the surface of the collector diagnostic. The analyses of the Ta collimators were presented to the Target and Laser Interaction Sphere (TaLIS) group; a representative presentation is attached to this document.
17. The fabricability and corrosion resistance of several Al-Cu-Li aerospace alloys
SciTech Connect
Walsh, D.W.; Danford, M.; Sanders, J.
1996-12-31
Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities. The objectives of this study were to measure the fabricability of Al 2195 (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior. Al 2219 samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to 3.5% NaCl and mild corrosive water solutions in both the as received and as welded conditions. Fabricability was assessed using Gleeble testing, Varestraint testing and differential scanning calorimetry (DSC). Results indicate that Alloy 2195 is much more susceptible to hot cracking than Al 2219, and that cracking sensitivity is a strong function of chemical composition within specification ranges for Al 2195. Furthermore, for base metal samples, corrosion in mild corrosive water was more severe than corrosion in salt water. In addition, welding increases the corrosion rate in Al 2195 and 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples and autogenously welded Al2219 samples were less susceptible to corrosion than autogenously welded Al 2195 samples. Heterogeneously welded samples in both materials had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In all cases, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. Fabricability and corrosion resistance were correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis, polarization resistance and environmental scanning electron microscopy.
18. Composition dependence of superconductivity in YBa2(Cu(3-x)Al(x))O(y)
NASA Technical Reports Server (NTRS)
Bansal, N. P.
1993-01-01
Eleven different compositions in the system YBa2(Cu(3-x)Al(x))O(y) (x = 0 to 0.3) have been synthesized and characterized by electrical resistivity measurements, powder X-ray diffraction, and scanning electron microscopy. The superconducting transition temperature T sub c (onset) was almost unaffected by the presence of alumina due to its limited solubility in YBa2Cu3O(7-x). However, T sub c(R = 0) gradually decreased, and the resistive tails became longer with increasing Al2O3 concentration. This was probably due to formation of BaAl2O4 and other impurity phases from chemical decomposition of the superconducting phase by reaction with Al2O3.
19. Composition dependence of superconductivity in YBa2(Cu(3-x)Al(x))Oy
NASA Technical Reports Server (NTRS)
Bansal, Narottam P.
1991-01-01
Eleven different compositions in the system YBa2(Cu(3-x)Al(x))O(y) (x = 0 to 0.3) have been synthesized and characterized by electrical resistivity measurements, powder x-ray diffraction, and scanning electron microscopy. The superconducting transition temperature T sub c (onset) was almost unaffected by the presence of alumina due to its limited solubility in YBa2Cu3O(7-x). However, T sub c(R = 0) gradually decreased, and the resistive tails became longer with increasing Al2O3 concentration. This was probably due to formation of BaAl2O4 and other impurity phases from chemical decomposition of the superconducting phase by reaction with Al2O3.
20. Plasticity-improved Zr-Cu-Al bulk metallic glass matrix composites containing martensite phase
SciTech Connect
Sun, Y.F.; Wei, B.C.; Wang, Y.R.; Li, W.H.; Cheung, T.L.; Shek, C.H.
2005-08-01
Zr{sub 48.5}Cu{sub 46.5}Al{sub 5} bulk metallic glass matrix composites with diameters of 3 and 4 mm were produced through water-cooled copper mold casting. Micrometer-sized bcc based B2 structured CuZr phase containing martensite plate, together with some densely distributed nanocrystalline Zr{sub 2}Cu and plate-like Cu{sub 10}Zr{sub 7} compound, was found embedded in a glassy matrix. The microstructure formation strongly depends on the composition and cooling rate. Room temperature compression tests reveal significant strain hardening and plastic strains of 7.7% and 6.4% before failure are obtained for the 3-mm- and 4-mm-diam samples, respectively. The formation of the martensite phase is proposed to contribute to the strain hardening and plastic deformation of the materials.
1. Large pinning forces and matching effects in YBa2Cu3O7-δ thin films with Ba2Y(Nb/Ta)O6 nano-precipitates
Opherden, Lars; Sieger, Max; Pahlke, Patrick; Hühne, Ruben; Schultz, Ludwig; Meledin, Alexander; van Tendeloo, Gustaaf; Nast, Rainer; Holzapfel, Bernhard; Bianchetti, Marco; MacManus-Driscoll, Judith L.; Hänisch, Jens
2016-02-01
The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O7‑δ (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m3 at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it.
2. Large pinning forces and matching effects in YBa2Cu3O7-δ thin films with Ba2Y(Nb/Ta)O6 nano-precipitates
PubMed Central
Opherden, Lars; Sieger, Max; Pahlke, Patrick; Hühne, Ruben; Schultz, Ludwig; Meledin, Alexander; Van Tendeloo, Gustaaf; Nast, Rainer; Holzapfel, Bernhard; Bianchetti, Marco; MacManus-Driscoll, Judith L.; Hänisch, Jens
2016-01-01
The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O7−δ (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m3 at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it. PMID:26887291
3. Microstructural characteristics and aging response of Zn-containing Al-Mg-Si-Cu alloy
Cai, Yuan-hua; Wang, Cong; Zhang, Ji-shan
2013-07-01
Al-Mg-Si-Cu alloys with and without Zn addition were fabricated by conventional ingot metallurgy method. The microstructures and properties were investigated using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), tensile test, hardness test, and electrical conductivity measurement. It is found that the as-cast Al-Mg-Si-Cu-Zn alloy is composed of coarse dendritic grains, long needle-like β/δ-AlFeSi white intermetallics, and Chinese script-like α-AlFeSi compounds. During high temperature homogenization treatment, only harmful needle-like β-AlFeSi phase undergoes fragmentation and spheroidizing at its tips, and the destructive needle-like δ-phase does not show any morphological and size changes. Phase transitions from β-AlFeSi to α-AlFeSi and from δ-AlFeSi to β-AlFeSi are also not found. Zn addition improves the aging hardening response during the former aging stage and postpones the peak-aged hardness to a long aging time. In T4 condition, Zn addition does not obviously increase the yield strength and decrease the elongation, but it markedly improves paint-bake hardening response during paint-bake cycle. The addition of 0.5wt% Zn can lead to an increment of 99 MPa in yield strength compared with the value of 69 MPa for the alloy without Zn after paint-bake cycle.
4. Electron transport in Al-Cu co-doped ZnO thin films
Serin, T.; Atilgan, A.; Kara, I.; Yildiz, A.
2017-03-01
To investigate the influence of varying Al content on structural, optical, and electrical properties of ZnO thin films, Al-Cu co-doped ZnO thin films with fixed Cu content at 1 wt. % and different Al contents (1, 3, and 5 wt. %) were successfully synthesized on glass substrates using a sol-gel process. The results indicated that the varying Al content affects not only the grain size and band gap but also the electrical conductivity of the films, and a linear relationship was found between the band gap and strain values of the films. The temperature-dependent electrical conductivity data of the films demonstrated that electron transport was mainly controlled by the grain boundaries at intermediate and high temperatures, whereas it was governed by Mott-variable range hopping at low temperatures. Additionally, 3 wt. % Al content improved the electrical conductivity of Al-Cu co-doped ZnO by lowering the trap density and enhancing the hopping probability.
5. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films
Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.
2016-07-01
Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.
6. Complete oxidation of volatile organic compounds over Ce/Cu/gamma-AL2O3 catalyst.
PubMed
Kim, S C; Shim, W G
2008-05-01
The effect of cerium (Ce) addition into Cu (5, 10 or 15 wt%)/gamma-Al2O3 catalysts on the catalyst properties and catalytic activity was investigated for the complete oxidation of volatile organic compounds (VOCs). X-ray diffraction (XRD), the Brunauer Emmett Teller method (BET), temperature programmed reduction (TPR) by H2, and N2O pulse titration were used to characterize a series of supported copper catalysts modified with cerium. Cerium was observed to be an inhibitor for 5 wt% and promoter for 10 or 15 wt% Cu/gamma-Al2O3 catalyst. The results of TPR, average crystallite size and dispersion indicated that even though Ce loadings on 10 and 15 wt% Cu/gamma-Al2O3 caused a reduction in BET surface area of the catalysts, the loaded amounts of Ce enhanced the catalytic activity through the formation of highly dispersed copper clusters. Kinetic parameters were developed for individual benzene, toluene and o-xylene (BTX) for 5 wt% Ce/10 wt% Cu/gamma-Al2O3 catalyst at temperatures ranging from 210 to 240 degrees C. The Mars and Van Krevelen model was found to be an adequate description of the catalytic oxidation of BTX for this study. The activity sequence with respect to the BTX molecules was found to be benzene > toluene > o-xylene under the surface-reaction-controlled region.
7. Influence of temperature on AC conductivity of nanocrystalline CuAlO2
Prakash, T.
2012-07-01
Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and α-Al2O3 powders in the molar ratio of 1:1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10:1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 473 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for AC conductivities, DC and AC conductivities correlations and crossover frequencies ( f co ). The BNN (Barton, Nakajima and Namikawa) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.
8. X-ray imaging and controlled solidification of Al-Cu alloys toward microstructures by design
SciTech Connect
Clarke, Amy J.; Tourret, Damien; Imhoff, Seth D.; Gibbs, Paul J.; Fezzaa, Kamel; Cooley, Jason C.; Lee, Wah -Keat; Deriy, Alex; Patterson, Brian M.; Papin, Pallas A.; Clarke, Kester D.; Field, Robert D.; Smith, James L.
2015-01-30
X-ray imaging, which permits the microscopic visualization of metal alloy solidification dynamics, can be coupled with controlled solidification to create microstructures by design. This x-ray image shows a process-derived composite microstructure being made from a eutectic Al-17.1 at.%Cu alloy by successive solidification and remelting steps.
9. Real-time investigations of selenization reactions in the system Cu-In-Al-Se
Jost, Stefan; Hergert, Frank; Hock, Rainer; Purwins, Michael; Enderle, Ralph
2006-09-01
In this article we present results of a detailed study of selenization reactions in the quaternary system Cu-In-Al-Se and of the binary subsystem aluminum-selenium. The investigation of solid-state reactions involved in the formation of the compound semiconductor Cu(In,Al)Se2 was performed using real-time X-ray diffraction (XRD) with a time resolution of 22.5 s while annealing an elemental layer stack of the metals covered with selenium. A temperature-resolved phase analysis shows that the formation of the semiconductor takes place via metal-selenides. Ex-situ XRD measurements of the processed thin films show a phase segregation concerning the aluminum content of the formed chalcopyrite. Subsequent Rietveld-refinement of real-time measurements reveals a formation reaction of the quaternary semiconductor Cu(In,Al)Se2 from the -In2Se3 related crystal structure of (Al,In)2Se3 and Cu2Se as educts.
10. High temperature oxidation resistance of Ni-(5˜13)Co-(10˜16)Cr-(5˜9)W-5Al-(1˜1.5)Ti-(3˜6)Ta alloys
Kim, Hee-Soo; Park, Si-Jun; Seo, Seong-Moon; Yoo, Young-Soo; Jeong, Hi-Won; Jang, HeeJin
2016-09-01
The oxidation behavior of Ni-based superalloys was examined by cyclic oxidation tests at 850 and 1000 °C. The present study focused on the investigation of two newly developed and three commercial alloys (GTD-111, IN738LC, and CM247LC). The oxidation resistance of the superalloys were evaluated by the oxidation rate constants and the mass gains. The oxidation scales mainly consisted of outer Cr2O3 and inner Al2O3 layers at both temperatures, as well as oxides of minor elements such as TiO2, NiCr2O4, CrTaO4, HfO2, and TaO. The oxidation resistance of the alloys containing larger amounts of Al, W, and Ta and lower Mo and Ti concentrations was higher than those of the other alloys. The ranking of oxidation resistance for the alloys corresponded to the statistical prediction drawn from a response surface analysis. Furthermore, these alloys contained more Ta oxides, such as CrTaO4 and TaO, suggesting that Ta oxides had an active role in improving the oxidation resistance.
11. Influence of temperature on Al/p-CuInAlSe2 thin-film Schottky diodes
Parihar, Usha; Ray, Jaymin; Panchal, C. J.; Padha, Naresh
2016-06-01
Al/p-CuInAlSe2 Schottky diodes were fabricated using the optimized thin layers of CuInAlSe2 semiconductor. These diodes were used to study their temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) analysis over a wide range of 233-353 K. Based on these measurements, diode parameters such as ideality factor ( η), barrier height (ϕbo) and series resistance ( R s) were determined from the downward curvature of I-V characteristics using Cheung and Cheung method. The extracted parameters were found to be strongly temperature dependent; ϕbo increases, while η and R s decrease with increasing temperature. This behavior of ϕbo and η with change in temperature has been explained on the basis of barrier inhomogeneities over the MS interface by assuming a Gaussian distribution (GD) of the ϕbo at the interface. GD of barrier height (BH) was confirmed from apparent BH (ϕap) versus q/2 kT plot, and the values of the mean BH and standard deviation (σs) obtained from this plot at zero bias were found to be 1.02 and 0.14 eV, respectively. Also, a modified ln ( {J_{{s}} /T2 } ) - q2 σ_{{s}}2 /2k2 T2 versus q/ kT plot for Al/p-CuInAlSe2 Schottky diodes according to the GD gives ϕbo and Richardson constant ( A ** ) as 1.01 eV and 26 Acm-2 K-2, respectively. The Richardson constant value of 26 Acm-2 K-2 is very close to the theoretical value of 30 Acm-2 K-2. The discrepancy between BHs obtained from I-V and C-V measurements has also been interpreted.
12. Effects of silicon content on the structure and mechanical properties of (AlCrTaTiZr)-Six-N coatings by reactive RF magnetron sputtering
Cheng, Keng-Hao; Tsai, Che-Wei; Lin, Su-Jien; Yeh, Jien-Wei
2011-05-01
Multi-component (AlCrTaTiZr)-Six-N films were deposited on silicon wafers by reactive RF magnetron co-sputtering. The effect of silicon content on the structure, morphology and mechanical properties of the nitride films was investigated. Nitride films with lower silicon content remained as a simple NaCl-type face-centred cubic (FCC) structure. As the silicon content reached 7.9 at%, thermodynamically driven phase separation occurred, leading to a nanocomposite structure consisting of an FCC solid-solution nitride and an amorphous SiNx phase. These nitride films exhibited a high hardness of 34 GPa and remained at a constant level up to 7.9 at% Si. The reduced hardness at a silicon content of 10.2 at% was attributed to the appreciable amounts of softer amorphous segregation. The silicon incorporation significantly improved the oxidation resistance of (AlCrTaTiZr)N films. The film containing 7.9 at% Si annealed at 1000 °C for 2 h in air only had a 330 nm-thick oxide layer. The optimum Si content is 7.9 at% since it gives the best combination of hardness and oxidation resistance.
13. A basin-hopping Monte Carlo investigation of the structural and energetic properties of 55- and 561-atom bimetallic nanoclusters: the examples of the ZrCu, ZrAl, and CuAl systems
De Souza, Douglas G.; Cezar, Henrique M.; Rondina, Gustavo G.; de Oliveira, Marcelo F.; Da Silva, Juarez L. F.
2016-05-01
We report a basin-hopping Monte Carlo investigation within the embedded-atom method of the structural and energetic properties of bimetallic ZrCu, ZrAl, and CuAl nanoclusters with 55 and 561 atoms. We found that unary Zr55, Zr561, Cu55, Cu561, Al55, and Al561 systems adopt the well known compact icosahedron (ICO) structure. The excess energy is negative for all systems and compositions, which indicates an energetic preference for the mixing of both chemical species. The ICO structure is preserved if a few atoms of the host system are replaced by different species, however, the composition limit in which the ICO structure is preserved depends on both the host and new chemical species. Using several structural analyses, three classes of structures, namely ideal ICO, nearly ICO, and distorted ICO structures, were identified. As the amounts of both chemical species change towards a more balanced composition, configurations far from the ICO structure arise and the dominant structures are nearly spherical, which indicates a strong minimization of the surface energy by decreasing the number of atoms with lower coordination on the surface. The average bond lengths follow Vegard’s law almost exactly for ZrCu and ZrAl, however, this is not the case for CuAl. Furthermore, the radial distribution allowed us to identify the presence of an onion-like behavior in the surface of the 561-atom CuAl nanocluster with the Al atoms located in the outermost surface shell, which can be explained by the lower surface energies of the Al surfaces compared with the Cu surfaces. In ZrCu and ZrAl the radial distribution indicates a nearly homogeneous distribution for the chemical species, however, with a slightly higher concentration of Al atoms on the ZrAl surface, which can also be explained by the lower surface energy.
14. Development of Cu alloy anode and separator coated with Al-Ni intermetallic compound
SciTech Connect
Toyokura, K.; Hoshino, K.; Yamamoto, M.
1996-12-31
Anode made of Cu alloy and separator coated with Al-Ni intermetallic compound have been developed for VCFC. Anode of Ni alloy is usually used. However, the alternative of cost lower than Ni alloy anode should be needed, because Ni is expensive. Cu is attractive as an anode material for VCFC because it is inexpensive and electrochemically noble. However, the creep resistance of Cu is not sufficient, compared with Ni alloy. In this study, strengthening due to oxide-dispersed microstructure has been developed in Cu-Ni-Al alloy with the two-step sintering process. A wet-seal technique has been widely applied for gas-sealing and supporting of electrolyte in MCFC. Since the wet-seal area is exposed to a severe corrosive environment, corrosion resistance of material for wet sealing is related with the cell performance. Al-Ni plating with post-heat treating for stainless steel has been investigated. Stainless steel substrate was plated with Al after being coated with Ni, then heat-treated at 750 {degrees}C for 1 hour in Ar gas atmosphere. Due to the treatment, Al-Ni intermetallic compound ( mainly Al3Ni2 ) layer is formed on stainless steel surface. The long-term immersion test was carried out till 14,500 hours in 62 mol% Li{sub 2}CO{sub 3}-38 mol% K{sub 2}CO{sub 3} at 650 {degrees}C under air-30%CO{sub 2} atmosphere, for the purpose of evaluating the corrosion resistance and thermal stability of Al-Ni intermetallic compound layer in actual generating with VCFC.
15. Unusual Solidification Behavior of the Suction-Cast Cu-Zr-Al-Y Alloy Doped with Fe
Kozieł, Tomasz; Cios, Grzegorz; Latuch, Jerzy; Pajor, Krzysztof; Bała, Piotr
2017-04-01
The effect of iron addition on the microstructure of the Cu-Zr-Al-Y glass-forming alloy was studied. Despite a high superficial cooling rate, small Fe additions (1.5 and 3 pct) induced formation of crystalline CuZr and AlCu2Zr phases on the outer layers of suction-cast rods. As the melt composition near the solid/liquid interface was depleted in Fe, the remaining melt vitrified at a relatively low cooling rate.
16. Al-Cu-Fe quasicrystal/ultra-high molecular weight polyethylene composites as biomaterials for acetabular cup prosthetics.
PubMed
Anderson, Brian C; Bloom, Paul D; Baikerikar, K G; Sheares, Valerie V; Mallapragada, Surya K
2002-04-01
Polymer composites of Al-Cu-Fe quasicrystals and ultra-high molecular weight polyethylene (UHMWPE) were investigated for use in acetabular cup prosthetics. The wear properties of the Al-Cu-Fe/UHMWPE samples and a 440 steel ball counterface were measured. The mechanical strength of the Al-Cu-Fe/UHMWPE composites was compared to UHMWPE and alumina/UHMWPE. The biocompatibility of the composite material was tested using a direct contact cytotoxicity assay. Al-Cu-Fe/UHMWPE demonstrated lower volume loss after wear and higher mechanical strength than UHMWPE. This composite material also showed no increase in counterface wear or cytotoxicity relative to UHMWPE. These combined results demonstrate that Al-Cu-Fe/UHMWPE composites are promising candidate materials for acetabular cup prosthetics.
17. Consistency in Al/CuPc/ n-Si Heterojunction Diode Parameters Extracted Using Different Techniques
Ullah, Irfan; Shah, Mutabar; Khan, Majid; Wahab, Fazal
2016-02-01
This paper reports fabrication and characterization of an Al/CuPc/ n-Si heterojunction diode. The heterojunction was fabricated by depositing the active organic semiconducting material copper phthalocyanine (CuPc) on the n-Si substrate using the thermal vacuum evaporation technique. Electrical characterization of the fabricated heterojunction was carried out at ambient conditions. Various diode parameters, such as the ideality factor ( n), barrier height (Φ_{{b}}), and series resistance ( R s), were extracted from the current-voltage ( I- V) characteristic curve. These parameters are consistent with techniques used by Cheung, Norde and Hernandez et al. Furthermore these parameters are consistent with capacitance-voltage (C-V) characterization method. The conduction mechanism at the interface of CuPc and n-Si was also investigated. The surface morphology of the CuPc film was studied using atomic force microscopy and scanning electron microscopy. The optical bandgap of the CuPc film was calculated from the absorption spectrum using Tauc's law.
18. Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals
SciTech Connect
Cai, Tanhong
2001-01-01
Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.
19. Tensile strength of Al matrix with nanoscale Cu, Ti and Mg inclusions
Pogorelko, V. V.; Mayer, A. E.
2016-11-01
Molecular-dynamic investigations of Al+Cu, Al+Ti and Al+Mg nanocomposite strength under high-rate uniaxial tension were carried out in this work. We consider two different mechanisms of reduction of the tensile strength of a material with inclusions in comparison with a pure material of matrix. The first mechanism is connected with a stress concentration in matrix near a stiff and strong inclusion (Ti, Cu); in this case, the fracture occurs inside the matrix and does not touch the inclusion. The second mechanism acts in the case of a soft and weak inclusion (Mg); the fracture begins inside the inclusion and thereafter propagates into the matrix. The tensile strength of the systems is determined at varied strain rates (in the range from 0.1/ns to 30/ns at the temperature 300 K) and varied temperatures (in the range from 300 K to 900 K at the strain rate 1/ns).
20. Electrical conduction mechanism in La{sub 3}Ta{sub 0.5}Ga{sub 5.3}Al{sub 0.2}O{sub 14} single crystals
SciTech Connect
Yaokawa, Ritsuko Aota, Katsumi; Uda, Satoshi
2013-12-14
The electrical conduction mechanism in La{sub 3}Ta{sub 0.5}Ga{sub 5.3}Al{sub 0.2}O{sub 14} (LTGA) single crystals was studied by nonstoichiometric defect formation during crystal growth. Since stoichiometric LTGA is not congruent, the single crystal grown from the stoichiometric melt was Ta-poor and Al-rich, where Al atoms were substituted not only in Ga sites but also in Ta sites. The population of the substitutional Al in Ta sites increased with increasing oxygen partial pressure during growth (growth-pO{sub 2}) in the range from 0.01 to 1 atm. Below 600 °C, substitutional Al atoms in Ta sites were ionized to yield holes, and thus the electrical conductivity of the LTGA crystal depended on temperature and the growth-pO{sub 2}. The dependence of the electrical conductivity on the growth-pO{sub 2} decreased as temperature increased. The temperature rise increases ionic conductivity, for which the dominant carriers are oxygen defects formed by the anion Frenkel reaction.
1. Effect of Surplus Phase on the Microstructure and Mechanical Properties in Al-Cu-Mg-Ag Alloys with High Cu/Mg Ratio
Xu, Xiaofeng; Zhao, Yuguang; Wang, Xudong; Zhang, Ming; Ning, Yuheng
2015-11-01
In order to examine the effect of surplus phase on the microstructure and mechanical properties, different compositions with high Cu/Mg ratio of the T6-temper extruded Al-Cu-Mg-Ag alloys were studied in this investigation. The results show that the Al-5.6Cu-0.56Mg-0.4Ag alloy obtains superior mechanical properties at room temperature, while the yield strength of Al-6.3Cu-0.48Mg-0.4Ag alloy is 378 MPa at 200 °C, which is 200 MPa higher than that of Al-5.6Cu-0.56Mg-0.4Ag alloy. Although the excessive Cu content causes the slight strength loss and elongation decrease in the Al-6.3Cu-0.48Mg-0.4Ag alloy at room temperature, the surplus phases and recrystallized microstructure will play an effective role in strengthening the alloy at elevated temperature.
2. Laser micro-processing of amorphous and partially crystalline Cu45Zr48Al7 alloy
Aqida, S. N.; Brabazon, D.; Naher, S.; Kovacs, Z.; Browne, D. J.
2010-11-01
This paper presents a microstructural study of laser micro-processed high-purity Cu45Zr48Al7 alloys prepared by arc melting and Cu-mould casting. Microprocessing of the Cu45Zr48Al7 alloy was performed using a Rofin DC-015 diffusion-cooled CO2 slab laser system with 10.6-μm wavelength. The laser was defocused to a spot size of 0.2 mm on the sample surface. The laser parameters were set to give 300- and 350-W peak power, 30% duty cycle and a 3000-Hz laser pulse repetition frequency (PRF). About 100-micrometer-wide channels were scribed on the surfaces of disk-shaped amorphous and partially crystalline samples at traverse speeds of 500 and 5000 mm/min. These channels were analysed using scanning electron microscopy (SEM) and 2D stylus profilometry. The metallographic study and profile of these processed regions are discussed in terms of the applied laser processing parameters. The SEM micrographs showed that striation marks developed at the edge and inside these regions as a result of the laser processing. The results from this work showed that microscale features can be produced on the surface of amorphous Cu-Zr-Al alloys by CO2 laser processing.
3. The response of macrophages to a Cu-Al-Ni shape memory alloy.
PubMed
Colić, Miodrag; Tomić, Sergej; Rudolf, Rebeka; Anzel, Ivan; Lojen, Gorazd
2010-09-01
Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but little is known about their biocompatibility. The aim of this work was to study the response of rat peritoneal macrophages (PMØ) to a Cu-Al-Ni SMA in vitro, by measuring the functional activity of mitochondria, necrosis, apoptosis, and production of proinflammatory cytokines. Rapidly solidified (RS) thin ribbons were used for the tests. The control alloy was a permanent mold casting of the same composition, but without the shape memory effect. Our results showed that the control alloy was severely cytotoxic, whereas RS ribbons induced neither necrosis nor apoptosis of PMØ. These findings correlated with the data that RS ribbons are significantly more resistant to corrosion compared to the control alloy, as judged by the lesser release of Cu and Ni in the conditioning medium. However, the ribbons generated intracellular reactive oxygen species and upregulated the production of IL-6 by PMØ. These effects were almost completely abolished by conditioning the RS ribbons for 5 weeks. In conclusion, RS significantly improves the corrosion stability and biocompatibility of Cu-Al-Ni SMA. The biocompatibility of this functional material could be additionally enhanced by conditioning the ribbons in cell culture medium.
4. Superelasticity of Cu-Ni-Al shape-memory fibers prepared by melt extraction technique
Li, Dong-yue; Zhang, Shu-ling; Liao, Wei-bing; Geng, Gui-hong; Zhang, Yong
2016-08-01
In the paper, a melt extraction method was used to fabricate Cu-4Ni-14Al (wt%) fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy (SEM) and a dynamic mechanical analyzer (DMA), respectively. Appropriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.
5. Evaluation of the mechanical properties of conventionally-cast Al matrix composites reinforced by quasicrystalline Al-Cu-Fe particles using continuous ball indentation technique
Fleury, E.; Lee, S. M.; Kim, W. T.; Kim, D. H.
2000-10-01
Room temperature mechanical properties of the Al/(AlCuFe)p and Al96Cu4/(AlCuFe)p cast composites were estimated from uniaxial compressive test and continuous ball indentation technique. Values of the Young's modulus and yield stress determined from continuous ball indentation tests were slightly overestimated, suggesting a surface effect on the mechanical properties. However, it was shown that the Al-Cu-Fe particles provided a significant increase of the elastic modulus, yield stress, and strain hardening, especially in the range up to 10% volume fraction of reinforcements. Also, determination of the hardness by continuous-ball-indentation tests revealed a strong influence of the matrix strength on the mechanical properties of the conventionally cast composites.
6. Preparation of (5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) nanocatalysts and application in sonocatalytic decomposition of ametryn in aqueous solution.
PubMed
Li, Guanshu; Zhang, Hongbo; Wei, Chunsheng; Huang, Yingying; Dou, Xuekai; Wang, Yidi; Wang, Jun; Song, Youtao
2017-01-01
(5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) powder, as a high effective sonocatalyst, was prepared using sol-gel and calcination method. Then it was characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). In order to evaluate the sonocatalytic activity of the prepared (5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) powder, the sonocatalytic decomposition of ametryn was studied. In addition, some influencing factors such as different Ti/Ta molar ratios on the sonocatalytic activity of the prepared (5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) powder, catalyst added amount with ultrasonic irradiation time and used times on the sonocatalytic decomposition efficiency were examined by using ion chromatogram determination. The experimental results showed that the best sonocatalytic decomposition ratio of ametryn were 77.50% based on the N atom calculation and 95.00% based on the S atom calculation, respectively, when the conditions of 10.00mg/L initial concentration, 1.00g/L prepared (5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) powder (Ti/Ta=1.00:0.25 heat-treated at 550°C for 3.0h) added amount, 150min ultrasonic irradiation (40kHz frequency and 300W output power), 100mL total volume and 25-28°C temperature were adopted. Therefore, the (5.0%)Er(3+):Y3Al5O12/Pt-(TiO2-Ta2O5) composite nanoparticles could be considered as an effective sonocatalyst for decomposition of ametryn in aqueous solution.
7. Study on the Microstructure and Wettability of an Al-Cu-Si Braze Containing Small Amounts of Rare Earth Erbium
Shi, Yaowu; Yu, Yang; Li, Yapeng; Xia, Zhidong; Lei, Yongping; Li, Xiaoyan; Guo, Fu
2009-04-01
The effect of adding small amounts of rare earth Er on the microstructure of an Al-Cu-Si braze alloy has been investigated. Several Al-20Cu-7Si braze alloys containing various contents of Er were prepared, and their melting temperature, microstructure, hardness, and wettability in contact with 3003 aluminum alloy substrates were determined. The results indicate that the constituents of the microstructure of Al-20Cu-7Si-Er braze alloys are similar to those in the Al-20Cu-7Si alloy, and comprise of solid solutions of aluminum, silicon, and the intermetallic compound CuAl2. When the Er content increases, the size of the Al phase decreases, and the needle-like Si phase is thickened, and transformed to a blocky shape. Moreover, small amounts of Er can improve the wettability and hardness of the Al-20Cu-7Si braze alloy; however, the melting temperature of the Al-20Cu-7Si alloy does not change.
8. Effects of Fabrication Parameters on Interface of Zirconia and Ti-6Al-4V Joints Using Zr55Cu30Al10Ni5 Amorphous Filler
Liu, Yuhua; Hu, Jiandong; Shen, Ping; Guo, Zuoxing; Liu, Huijie
2013-09-01
ZrO2 was brazed to Ti-6Al-4V using a Zr55Cu30Al10Ni5 (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO2/ZrO2- x + TiO/(Zr,Ti)2(Cu,Ni)/(Zr,Ti)2(Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO2- x + TiO layer and the content of the (Zr,Ti)2(Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti)2(Cu,Ni) phase decreased, and the thickness of the (Zr,Ti)2(Cu,Ni) + (Zr,Ti)2(Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO2 side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO2 and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.
9. The Effect of Al2Cu Precipitate Size on Microstructure and Mechanical Properties of Al-2 wt.%Cu Alloys Fabricated by ARB
2015-12-01
The effect of pre-existing precipitates on microstructure evolution, mechanical properties, and fracture behavior of Al-2 wt.%Cu alloy during accumulative roll-bonding (ARB) process was investigated. Aging treatment was done on Al-2 wt.%Cu alloy in order to produce the nano-particle size precipitates. The microstructure evolution was studied using transmission electron microscope and electron backscattering diffraction (EBSD), and mechanical properties were investigated using tensile test and Vickers microhardness measurements. The fine precipitates were formed after the aging process and improved the mechanical properties in the Aged-specimen compared to the solution-treated (ST) specimen. The EBSD analysis showed that the grain size after 6-cycle ARB process has decreased down to 650 and 420 nm for the ST-ARB and the Aged-ARB specimens, respectively. Also, with increasing the number of the ARB cycles, the fraction of HAGBs is increased in both the ST and Aged-specimens. It was found that as the number of cycles increased, the Vickers microhardness value and the yield strength and the tensile strength increased. The scanning electron microscope (SEM) images showed that as the number of the ARB cycles increased, the dimple size became smaller.
10. Dynamic mechanical analyze of superelastic CuMnAl shape memory alloy
(Dragoș Ursanu, A. I.; Stanciu, S.; Pricop, B.; Săndulache, F.; Cimpoeșu, N.
2016-08-01
A new shape memory alloy was obtain from high purity Cu, Mn and Al elements using a induce furnace. The intelligent material present negative transformation temperatures and an austenite like state at room temperature. The austenite state of CuMnAl shape memory alloy present superelasticity property. Five kilograms ingot was obtain of Cu10Mn10Al alloy. From the base material (melted state) were cut samples with 6 mm thickness using a mechanical saw. After an homogenization heat treatment the samples were hot rolled through four passes with a reduction coefficient of 20%. Experimental lamellas were obtained with 1.5 mm thickness and 90x10 mm length and width. After the hot rolled treatment the materials were heat treated at 800°C for 20 minutes and chilled in water. Four samples, one just laminated and three heat treated by aging, were analyzed with a Netzsch DMA equipment to establish the elastic modulus and the internal friction values of the materials. Metallic materials microstructure was analyzed using a scanning electron microscope Vega Tescan LMH II type. After the aging heat treatment a decrease of internal friction is observed on the entire analyze range which is assigned to formation of Al-based precipitates that block the internal movement of the alloy characteristic phases.
11. Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.
PubMed
Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru
2005-05-01
It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces.
12. Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding
Fiori, F.; Marcantoni, M.
Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (tensile-strength tests) of the welded interface.
13. Incommensurate modulated structure study of a Cu-Zn-Al-Zr phase
SciTech Connect
Chung, C.Y.; Zou, W.H.; Han, X.D.; Lam, C.W.H.; Lai, J.K.L.; Gao, M.; Duan, X.F.
1998-09-18
Zr was added to Cu-Zn-Al shape memory alloy as a grain refinement element. There are two new phases, Cu{sub 50.2}Zr{sub 24.6}Al{sub 17.3}Zn{sub 7.9} (at%) (Z{sub 1} phase) and Cu{sub 57.4}Zr{sub 20.4}Zn{sub 10.3}Al{sub 11.9} (at%) (Z{sub 2}) phase is studied in detail in the present paper. The results of electron diffraction and high-resolution electron microscopy (HREM) investigations indicated a one-dimensional incommensurate modulated structure in the Z{sub 2} phase. The average structure of the phase is base-centered orthorhombic. The systematic reflection conditions associated with the main and satellite reflections demonstrate that the Bravais class of the Z{sub 2} phases is P{sub 11{bar 1}}{sup Cmmm} type in a (3 + 1) dimensional space for the incommensurate modulated structure. The substitution modulation effects of the Al and Zr elements are revealed by energy-filtered transmission electron microscopy (EFTEM), {l_brace}1{bar 3}{bar 2}{r_brace} compound-type twins are observed in the Z{sub 2} phase. The relationship between the Z{sub 1} and Z{sub 2} phases in the alloy is discussed.
14. Electroactive complex in thermally treated Ge-Si <Cu, Al> crystals
SciTech Connect
Azhdarov, G. Kh.; Zeynalov, Z. M.; Zakhrabekova, Z. M.; Kyazimova, A. I.
2010-05-15
It is shown by Hall measurements that quenching complexly doped Ge{sub 1-x}Si{sub x}<Cu, Al> (0 {<=} x {<=} 0.20) crystals from 1050-1080 K leads to the formation of additional electroactive acceptor centers in them. The activation energy of these centers increases linearly with an increase in the silicon content in the crystal and is described by the relation E{sub k}{sup x} = (52 + 320x) meV. Annealing these crystals at 550-570 K removes the additional acceptor levels. It is established that the most likely model for the additional electroactive centers is a pair composed of substituent copper and aluminum atoms (Cu{sub s}Al{sub s}) or interstitial copper and substituent aluminum atoms (Cu{sub i}Al{sub s}). It is shown that the generation of additional deep acceptor levels must be taken into account when using the method of precise doping of Ge{sub 1-x}Si{sub x}<Al> crystals with copper.
15. The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles
SciTech Connect
Tang, Fei
2004-01-01
Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of
16. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al. Part 1; Oxidation Kinetics
NASA Technical Reports Server (NTRS)
Raj, S. V.
2008-01-01
The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu-17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9+/-9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr-5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR-5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.
17. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics
NASA Technical Reports Server (NTRS)
Raj. Sai V.
2008-01-01
The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 +/- 9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.
18. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics
NASA Technical Reports Server (NTRS)
Raj. Sai V.
2008-01-01
The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 9.5 kJ mol-1. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.
19. Effect of the valence electron concentration on the bulk modulus and chemical bonding in Ta{sub 2}AC and Zr{sub 2}AC (A=Al, Si, and P)
SciTech Connect
Schneider, Jochen M.; Music, Denis; Sun Zhimei
2005-03-15
We have studied the effect of the valence electron concentration, on the bulk modulus and the chemical bonding in Ta{sub 2}AC and Zr{sub 2}AC (A=Al, Si, and P) by means of ab initio calculations. Our equilibrium volume and the hexagonal ratio (c/a) agree well (within 2.7% and 1.2%, respectively) with previously published experimental data for Ta{sub 2}AlC. The bulk moduli of both Ta{sub 2}AC and Zr{sub 2}AC increase as Al is substituted with Si and P by 13.1% and 20.1%, respectively. This can be understood since the substitution is associated with an increased valence electron concentration, resulting in band filling and an extensive increase in cohesion.
20. Characterization of write-once blu-ray disk containing Cu-Al/Si recording layer using transmission electron microscopy
Mai, Hung-Chuan; Hsieh, Tsung-Eong; Jeng, Shiang-Yao
2011-02-01
Microstructure change in write-once blu-ray disk containing Cu-Al/Si recording layer was investigated by transmission electron microscopy. Nanoscale crystallites were found to comprise of the Cu-Al/Si recording layer before and after signal writing and the energy dispersive spectroscopy revealed insignificant composition fluctuation in disk sample. Analytical results indicated the signal properties of disk samples are correlated with a moderate improvement of crystallinity and the formation of Cu and Si solid-solution phases due to element mixing in mark area, rather than the formation of Cu3Si silicide and recrystallization of recording layer as reported by previous studies.
1. The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18
Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.
2015-02-01
In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.
2. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates
Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong
2017-01-01
Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.
3. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates
Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong
2016-10-01
Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.
4. Effect of Interfacial Microstructure Evolution on Mechanical Properties and Fracture Behavior of Friction Stir-Welded Al-Cu Joints
Xue, P.; Xiao, B. L.; Ma, Z. Y.
2015-07-01
The interfacial microstructure evolution of Al-Cu joints during friction stir welding and post-welding annealing and its influence on the tensile strength and the fracture behavior were investigated in detail. An obvious interface including three sub-layers of α-Al, Al2Cu, and Al4Cu9 intermetallic compound (IMC) layers is generated in the as-FSW joint. With the development of annealing process, the α-Al layer disappeared and a new IMC layer of AlCu formed between initial two IMC layers of Al2Cu and Al4Cu9. The growth rate of IMC layers was diffusion controlled before the formation of Kirkendall voids, with activation energy of 117 kJ/mol. When the total thickness of IMC layers was less than the critical value of 2.5 μm, the FSW joints fractured at the heat-affected zone of Al side with a high ultimate tensile strength (UTS) of ~100 MPa. When the thickness of IMC layers exceeded 2.5 μm, the joints fractured at the interface. For relatively thin IMC layer, the joints exhibited a slightly decreased UTS of ~90 MPa and an inter-granular fracture mode with crack propagating mainly between the Al2Cu and AlCu IMC layers. However, when the IMC layer was very thick, crack propagated in the whole IMC layers and the fracture exhibited trans-granular mode with a greatly decreased UTS of 50-60 MPa.
5. Phase transformation induced resistive switching behavior in Al/Cu2Se/Pt
Rehman, Shania; Kim, Kihwan; Hur, Ji-Hyun; Kim, Deok-kee
2017-04-01
The phase transformation induced resistive switching behavior of an Al/Cu2Se/Pt device was studied. While the device did not demonstrate any resistive switching behavior at room temperature, it exhibited resistive switching behavior at 125 °C, near the transition temperature of copper(I) selenide (Cu2Se) (137 °C), where Cu2Se is known to transform from the monoclinic to superionic phase. The increase in ionic conductivity and structural variations (from ordered to disordered structure) associated with phase transformation were observed to be responsible for the origin of the switching behavior and increase in the on/off resistance ratio near the transition temperature. Thermodynamic calculations showed that a reduction in Gibb’s free energy of nucleation and an increase in the migration speed of the Cu ion associated with the ionic conductivity and order to disorder the transition of the Cu2Se at the transition temperature were the important factors responsible for the reduction in the SET voltages at 155 °C.
6. Ion irradiation induced nanocrystal formation in amorphous Zr 55Cu 30Al 10Ni 5 alloy
Carter, Jesse; Fu, E. G.; Martin, Michael; Xie, Guoqiang; Zhang, X.; Wang, Y. Q.; Wijesundera, D.; Wang, X. M.; Chu, Wei-Kan; McDeavitt, Sean M.; Shao, Lin
2009-09-01
Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr 55Cu 30Al 10Ni 5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 × 10 16 cm -2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5-10 nm and another with diameters of 50-100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings ( d-values) agree with the expectations for Cu 10Zr 7, NiZr 2 and CuZr 2 phases. We further discussed the possibility to form a substitutional intermetallic (Ni xCu 1-x)Zr 2 phase.
7. [NOx storage and decomposition behavior of Cu-Mg-Al catalyst].
PubMed
Kang, Shou-fang; Li, Jun-hua; Fu, Li-xin; Hao, Zheng-ping
2007-05-01
Cu-Mg-Al hydrotalcite mixed oxide was prepared by co-precipitation. The mixed oxide and its procurer were characterized by XRD. NO, storage performance and decomposition of the stored NO, over the catalyst were investigated by NO, storage experiment at constant temperature, temperature programmed desorption (TPD) and temperature programmed surface reaction (TPSR), respectively. The results indicate that Cu-Mg-Al hydrotalcite mixed oxide has a good performance of NO, storage. The formed nitrate can be decomposed to gaseous NOx rapidly in the investigated temperature range of 160-360 degrees C, and a small amount of gaseous NO, can be reduced by C3 H6 with increasing the concentration of C3 H6 in the inlet gas.
8. Microstructural evolution of Al-Cu thin-film conducting lines during post-pattern annealing
SciTech Connect
Kang, S.H.; Morris, J.W. , Jr. |
1997-07-01
This work reports a statistical analysis of the evolution of polygranular segment lengths during high-temperature annealing of Al(Cu) thin-film interconnects with quasi-bamboo microstructures. To create samples of Al(Cu) lines that could be imaged by transmission electron microscopy without breaking or thinning, the lines were deposited on electron-transparent silicon nitride films (the {open_quotes}silicon nitride window{close_quotes} technique). The microstructures of the lines were studied as a function of annealing time and temperature. In particular, the distribution of polygranular segment lengths was measured. The results show that the longer polyglranular segments are preferentially eliminated during post-pattern annealing. As a consequence, the segment-length distribution narrows monotonically during annealing, and changes in shape. The preferential loss of the longest polygranular segments leads to a dramatic increase in resistance to electromigration failure.
9. Solidification analysis of a centrifugal atomizer using the Al-32.7wt.% Cu alloy
SciTech Connect
Osborne, Matthew G.
1998-02-23
A centrifugal atomizer (spinning disk variety) was designed and constructed for the production of spherical metal powders, 100-1,000 microns in diameter in an inert atmosphere. Initial atomization experiments revealed the need for a better understanding of how the liquid metal was atomized and how the liquid droplets solidified. To investigate particle atomization, Ag was atomized in air and the process recorded on high-speed film. To investigate particle solidification, Al-32.7 wt.% Cu was atomized under inert atmosphere and the subsequent particles were examined microscopically to determine solidification structure and rate. This dissertation details the experimental procedures used in producing the Al-Cu eutectic alloy particles, examination of the particle microstructures, and determination of the solidification characteristics (e.g., solidification rate) of various phases. Finally, correlations are proposed between the operation of the centrifugal atomizer and the observed solidification spacings.
10. Superplastic formability of Al-Cu-Li alloy Weldalite (TM) 049
NASA Technical Reports Server (NTRS)
Ma, Bao-Tong; Pickens, Joseph R.
1991-01-01
Extensive research during the past decade shows that several aluminum lithium alloys can be processed to attain a microstructure that enables superplasticity. The high tensile stress of Al-Cu-Li alloy Weldalite (TM) 049 in the T4 and T6 tempers offers tremendous potential for attaining exceptional post-SPF (superplastic formability) properties. The used SPF material is Weldalite, which was shown to induce SPF behavior in other Al-Cu-Li alloys. The superplastic behavior and resulting post-SPF mechanical properties of this alloy, which was designed to be the next major structural alloy for space applications, were evaluated. The results indicate that Weldalite alloy does indeed exhibit excellent superplasticity over a wide range of temperatures and strain rates and excellent post-SPF tensile strength at various potential service temperatures.
11. Aqueous sodium chloride induced intergranular corrosion of Al-Li-Cu alloys
NASA Technical Reports Server (NTRS)
Pizzo, P. P.; Daeschner, D. L.
1986-01-01
Two methods have been explored to assess the susceptibility of Al-Li-Cu alloys to intergranular corrosion in aqueous sodium chloride solution. They are: (1) constant extension rate testing with and without alternate-immersion preexposure and (2) metallographic examination after exposure to a NaCl-H2O2 corrosive solution per Mil-H-6088F. Intergranular corrosion was found to occur in both powder and ingot metallurgy alloys of similar composition, using both methods. Underaging rendered the alloys most susceptible. The results correlate to stress-corrosion data generated in conventional time-to-failure and crack growth-rate tests. Alternate-immersion preexposure may be a reliable means to assess stress corrosion susceptibility of Al-Li-Cu alloys.
12. Synthesis, characterization and physical properties of Al-Cu-Fe quasicrystalline plasma sprayed coatings
SciTech Connect
Daniel, Sordelet
1995-11-09
Our lab has been working with plasma spraying of both high pressure gas atomized (HPGA) and cast and crushed quasicrystal powders. A major component of this research includes comparative studies of PAS coatings formed with starting powders prepared by both techniques. In addition, a thorough investigation of the effects of starting powder particle size on coating microstructure is included. During the course of the overall research, an interest developed in forming Al-Cu-Fe materials with finer grain sizes. Therefore, a brief study was performed to characterize the effect of adding boron to Al-Cu-Fe materials prepared by different techniques. In addition to characterizing the microstructural features of the above materials, oxidation and wear behavior was also examined.
13. Evaluation of Laser Braze-welded Dissimilar Al-Cu Joints
Schmalen, Pascal; Plapper, Peter
The thermal joining of Aluminum and Copper is a promising technology towards automotive battery manufacturing. The dissimilar metals Al-Cu are difficult to weld due to their different physicochemical characteristics and the formation of intermetallic compounds (IMC), which have reduced mechanical and electric properties. There is a critical thickness of the IMCs where the favored mechanical properties of the base material can be preserved. The laser braze welding principle uses a position and power oscillated laser-beam to reduce the energy input and the intermixture of both materials and therefore achieves minimized IMCs thickness. The evaluation of the weld seam is important to improve the joint performance and enhance the welding process. This paper is focused on the characterization and quantification of the IMCs. Mechanical, electrical and metallurgical methods are presented and performed on Al1050 and SF-Cu joints and precise weld criteria are developed.
14. Effect of homogenization process on the hardness of Zn-Al-Cu alloys
Villegas-Cardenas, Jose D.; Saucedo-Muñoz, Maribel L.; Lopez-Hirata, Victor M.; De Ita-De la Torre, Antonio; Avila-Davila, Erika O.; Gonzalez-Velazquez, Jorge Luis
2015-10-01
The effect of a homogenizing treatment on the hardness of as-cast Zn-Al-Cu alloys was investigated. Eight alloy compositions were prepared and homogenized at 350 °C for 180 h, and their Rockwell "B" hardness was subsequently measured. All the specimens were analyzed by X-ray diffraction and metallographically prepared for observation by optical microscopy and scanning electron microscopy. The results of the present work indicated that the hardness of both alloys (as-cast and homogenized) increased with increasing Al and Cu contents; this increased hardness is likely related to the presence of the θ and τ' phases. A regression equation was obtained to determine the hardness of the homogenized alloys as a function of their chemical composition and processing parameters, such as homogenization time and temperature, used in their preparation.
15. Unique properties of CuZrAl bulk metallic glasses induced by microalloying
SciTech Connect
Huang, B.; Bai, H. Y.; Wang, W. H.
2011-12-15
We studied the glass forming abilities (GFA), mechanical, and physical properties of (CuZr){sub 92.5}Al{sub 7}X{sub 0.5} (X = La, Sm, Ce, Gd, Ho, Y, and Co) bulk metallic glasses (BMGs). We find that the GFA, mechanical, and physical properties can be markedly changed and modulated by the minor rare earth addition. The Kondo screening effect is found to exist in (CuZr){sub 92.5}Al{sub 7}Ce{sub 0.5} BMG at low temperatures and the Schottky effect exists in all the rare earth element doped BMGs. Our results indicate that the minor addition is an effective way for modulating and getting desirable properties of the BMGs. The mechanisms of the effects of the addition are discussed. The results have implications for the exploration of metallic glasses and for improving the mechanical and low temperature physical properties of BMGs.
16. Elevated temperature flow strength, creep resistance and diffusion welding characteristics of Ti-6Al-2Nb-1Ta-0.8Mo
NASA Technical Reports Server (NTRS)
Whittenberger, J. D.; Moore, T. J.
1979-01-01
A study of the flow strength, creep resistance and diffusion welding characteristics of the titanium alloy Ti-6Al-2Nb-1Ta-0.8Mo has been conducted. Two mill-processed forms of this alloy were examined. The forged material had been processed above the beta transus (approximately 1275 K) while the rolled form had been subjected to work below the beta transus. Between 1150 and 1250 K, the forged material was stronger and more creep resistant than the rolled alloy. Both forms exhibit superplastic characteristics in this temperature range. Strain measurements during diffusion welding experiments at 1200 K reveal that weld interfaces have no measurable effect on the overall creep deformation. Significant deformation appears to be necessary to produce a quality diffusion weld between superplastic materials. A 'soft' interlayer inserted between faying surfaces would seemingly allow manufacture of quality diffusion welds with little overall deformation.
17. Elevated-temperature flow strength, creep resistance and diffusion welding characteristics of Ti-gAl-2Nb-1Ta-0.8Mo
NASA Technical Reports Server (NTRS)
Whittenberger, J. D.; Moore, T. J.
1977-01-01
A study of the flow strength, creep resistance and diffusion welding characteristics of the titanium alloy Ti-6Al-2Nb-1Ta-0.8Mo was conducted. Two mill-processed forms of this alloy were examined. The forged material was essentially processed above the beta transus while the rolled form was subjected to considerable work below the beta transus. Between 1150 and 1250 K, the forged material was stronger and more creep resistant than the rolled alloy. Both forms exhibit superplastic characteristics in this temperature range. Strain measurements during diffusion welding experiments at 1200 K reveal that weld interfaces have no measurable effect on the overall creep deformation. Significant deformation appears to be necessary to produce a quality diffusion weld between superplastic materials. A 'soft' interlayer inserted between faying surfaces would seemingly allow manufacture of quality diffusion welds with little overall deformation.
18. Effect of ZrO2 Nanoparticles on the Microstructure of Al-Si-Cu Filler for Low-Temperature Al Brazing Applications
Sharma, Ashutosh; Roh, Myung-Hwan; Jung, Do-Hyun; Jung, Jae-Pil
2016-01-01
In this study, the effect of ZrO2 nanoparticles on Al-12Si-20Cu alloy has been studied as a filler metal for aluminum brazing. The microstructural and thermal characterizations are performed using X-ray diffraction (XRD), scanning electron microscope (SEM), and differential thermal analysis (DTA). The intermetallic compound (IMC) phases are identified by the energy-dispersive spectroscopy analysis coupled with the SEM. The filler spreading test is performed according to JIS-Z-3197 standard. XRD and SEM analyses confirm the presence of Si particles, the CuAl2 ( θ) intermetallic, and the eutectic structures of Al-Si, Al-Cu, and Al-Si-Cu in the Al matrix in the monolithic and composite samples. It is observed that when the ZrO2 is added in the alloy, the CuAl2 IMCs and Si particles are found to be dispersed uniformly in the Al matrix up to 0.05 wt pct ZrO2. DTA results show that the liquidus temperature of Al-12Si-20Cu filler metal is dropped from ~806.78 K to 804.6 K (533.78 °C to 531.6 °C) with a lowering of 2 K (2 °C) in liquidus temperature, when the amount of ZrO2 is increased up to 0.05 wt pct. It is also shown that the presence of ZrO2 nanoparticles in the filler metal has no deleterious effect on wettability up to 0.05 wt pct of ZrO2. The ultimate tensile strength and elongation percentage are also found to improve with the addition of ZrO2 nanoparticles in the Al-12Si-20Cu alloy.
19. The Influence of Composition on the Clustering and Precipitation Behavior of Al-Mg-Si-Cu Alloys
Jia, Zhihong; Ding, Lipeng; Cao, Lingfei; Sanders, Robert; Li, Shichen; Liu, Qing
2017-01-01
The natural aging (NA) and artificial aging (AA) behavior of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions were systematically investigated by means of hardness test, atom probe tomography, transmission electron microscopy, and Monte Carlo simulation. The Si-rich low-Cu alloys displayed higher hardness compared to the Mg-rich equivalents because Si atoms play a dominant role in clustering of solute atoms during both natural and artificial aging. In the high-Cu alloys, Cu did not obviously change the cluster distribution during NA, but significantly refines the clusters and precipitates due to the strong interaction of Cu atoms with Mg atoms during AA. In contrast to the low-Cu alloys, the Mg-rich high-Cu alloys exhibit higher hardness in the early and over-aged stages of artificial aging, with similar or slightly higher hardness in the peak aging condition compared to their Si-rich counterparts. Three types of precipitates ( β″, Q', and L) are favored in the high-Cu alloys. The Mg-rich high-Cu alloy has more L phase, while the Si-rich variant is abundant in Q' phase. The negative effect of NA on subsequent AA behavior is less dependent on Mg/Si ratio in the high-Cu alloys due to a synergistic action of the residual Si and Cu atoms, but is closely related to Mg/Si ratio in low-Cu alloys.
20. Interface morphology and mechanical properties of Al-Cu-Al laminated composites fabricated by explosive welding and subsequent rolling process
2016-07-01
Explosive welding is a well-known solid state method for joining similar and dissimilar materials. In the present study, tri-layered Al-Cu-Al laminated composites with different interface morphologies were fabricated by explosive welding and subsequent rolling. Effects of explosive ratio and rolling thickness reduction on the morphology of interface and mechanical properties were evaluated through optical/scanning electron microscopy, micro-hardness, tensile and tensile-shear tests. Results showed that by increasing the thickness reduction, bonding strength of specimens including straight and wavy interfaces increases. However, bonding strength of the specimens with melted layer interface decreases up to a threshold thickness reduction, then rapidly increases by raising the reduction. Hardness Values of welded specimens were higher than those of original material especially near the interface and a more uniform hardness profile was obtained after rolling process.
1. The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys
NASA Technical Reports Server (NTRS)
Gilman, P. S.
1984-01-01
Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.
2. Effect of cooling rate on the microstructure and microhardness of the CuZrAgAl alloy
SciTech Connect
Liu, Y.; Blandin, J.J.; Suery, M.; Kapelski, G.
2012-08-15
The effect of cooling rate on the microstructure and microhardness of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} (at.%) alloy has been studied. The crystalline phases were characterized by X-ray diffraction, optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy, and identified as AlCu{sub 2}Zr, Cu{sub 10}Zr{sub 7} and CuZr{sub 2}. The solidification sequence was established as following: the Cu{sub 10}Zr{sub 7} phase forms first in the periphery of the rod, then following with AlCu{sub 2}Zr phase in the rod center and finally CuZr{sub 2} crystals in Cu-depleted areas. The effect of crystals on the mechanical properties of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was also estimated through the microhardness. According to the value of microhardness, inhomogeneous structure of the amorphous matrix is more easily formed for the alloy in the low cooling rate (i.e., 9 mm) as compared with the alloy with fully amorphous state in the large cooling rate (i.e., 3 mm). This inhomogeneous structure was attributed to the composition change of amorphous matrix arising from the forming of crystalline phases due to the low cooling rate. - Highlights: Black-Right-Pointing-Pointer The crystalline phases in the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy were identified. Black-Right-Pointing-Pointer The solidification sequence of Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was verified. Black-Right-Pointing-Pointer The softening and hardening of alloy could be observed due to the crystallization.
3. Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory
NASA Technical Reports Server (NTRS)
Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John
1993-01-01
Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.
4. Bulk Properties of Ni3Al(gamma') With Cu and Au Additions
NASA Technical Reports Server (NTRS)
Bozzolo, Guillermo; Ferrante, John
1995-01-01
The BFS method for alloys is applied to the study of 200 alloys obtained from adding Cu and Au impurities to a Ni3Al matrix. We analyze the trends in the bulk properties of these alloys (heat of formation, lattice parameter, and bulk modulus) and detect specific alloy compositions for which these quantities have particular values. A detailed analysis of the atomic interactions that lead to the preferred ordering patterns is presented.
5. Bipolar resistive switching in Cu/AlN/Pt nonvolatile memory device
Chen, C.; Yang, Y. C.; Zeng, F.; Pan, F.
2010-08-01
Highly stable and reproducible bipolar resistive switching effects are reported on Cu/AlN/Pt devices. Memory characteristics including large memory window of 103, long retention time of >106 s and good endurance of >103 were demonstrated. It is concluded that the reset current decreases as compliance current decreases, which provides an approach to suppress power consumption. The dominant conduction mechanisms of low resistance state and high resistance state were verified by Ohmic behavior and trap-controlled space charge limited current, respectively. The memory effect is explained by the model concerning redox reaction mediated formation and rupture of the conducting filament in AlN films.
6. Microstructure control of Al-Cu films for improved electromigration resistance
DOEpatents
Frear, D.R.; Michael, J.R.; Romig, A.D. Jr.
1994-04-05
A process for the forming of Al-Cu conductive thin films with reduced electromigration failures is useful, for example, in the metallization of integrated circuits. An improved formation process includes the heat treatment or annealing of the thin film conductor at a temperature within the range of from 200 C to 300 C for a time period between 10 minutes and 24 hours under a reducing atmosphere such as 15% H[sub 2] in N[sub 2] by volume. Al-Cu thin films annealed in the single phase region of a phase diagram, to temperatures between 200 C and 300 C have [theta]-phase Al[sub 2] Cu precipitates at the grain boundaries continuously become enriched in copper, due, it is theorized, to the formation of a thin coating of [theta]-phase precipitate at the grain boundary. Electromigration behavior of the aluminum is, thus, improved because the [theta]-phase precipitates with copper hinder aluminum diffusion along the grain boundaries. Electromigration, then, occurs mainly within the aluminum grains, a much slower process. 5 figures.
7. Microstructure control of Al-Cu films for improved electromigration resistance
DOEpatents
Frear, Darrel R.; Michael, Joseph R.; Romig, Jr., Alton D.
1994-01-01
A process for the forming of Al-Cu conductive thin films with reduced electromigration failures is useful, for example, in the metallization of integrated circuits. An improved formation process includes the heat treatment or annealing of the thin film conductor at a temperature within the range of from 200.degree. C. to 300.degree. C. for a time period between 10 minutes and 24 hours under a reducing atmosphere such as 15% H.sub.2 in N.sub.2 by volume. Al-Cu thin films annealed in the single phase region of a phase diagram, to temperatures between 200.degree. C. and 300.degree. C. have .theta.-phase Al.sub.2 Cu precipitates at the grain boundaries continuously become enriched in copper, due, it is theorized, to the formation of a thin coating of .theta.-phase precipitate at the grain boundary. Electromigration behavior of the aluminum is, thus, improved because the .theta.-phase precipitates with copper hinder aluminum diffusion along the grain boundaries. Electromigration, then, occurs mainly within the aluminum grains, a much slower process.
8. Cu-Al-Ni Shape Memory Single Crystal Wires with High Transformation Temperature
NASA Technical Reports Server (NTRS)
Hautcoeur, Alain; Fouché, Florian; Sicre, Jacques
2016-01-01
CN-250X is a new material with higher performance than Nickel-Titanium Shape Memory Alloy (SMA). For space mechanisms, the main disadvantage of Nickel-Titanium Shape Memory Alloy is the limited transformation temperature. The new CN-250X Nimesis alloy is a Cu-Al-Ni single crystal wire available in large quantity because of a new industrial process. The triggering of actuators made with this Cu-Al-Ni single crystal wire can range from ambient temperature to 200 C in cycling and even to 250 C in one-shot mode. Another advantage of CN-250X is a better shape recovery (8 to 10%) than Ni-Ti (6 to 7%). Nimesis is the first company able to produce this type of material with its new special industrial process. A characterization study is presented in this work, including the two main solicitation modes for this material: tensile and torsion. Different tests measure the shape recovery of Cu-Al-Ni single crystals wires during heating from room temperature to a temperature higher than temperature of end of martensitic transformation.
9. Microstructure evolution and tensile mechanical properties of thixoformed high performance Al-Zn-Mg-Cu alloy
Chen, Gang; Chen, Qiang; Wang, Bo; Du, Zhi-ming
2015-09-01
Al-Zn-Mg-Cu alloys are the strongest aluminum alloys which have been widely used for aerospace applications. They are usually machined from the wrought state usually with a high waste percentage. To reduce waste, it is important to thixoform these alloys in near net shape. In this work, the thixoformability of a commercial high performance Al-Zn-Mg-Cu alloy 7075 was studied. A novel multistep reheating regime was developed in recrystallization and partial melting (RAP) route to obtain spheroidal semi-solid microstructures. The as-extruded 7075 alloy was fully recrystallized for a short holding time using the multistep reheating regime. Semi-solid microstructures with fine and spherical solid grains with a grain size of 40-50 μm embedded in liquid matrix were obtained. The advantage of the multistep reheating regimes over those conventional routes was also discussed. Some wheel-shaped components were thixoformed from the as-received 7075 alloy. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed component based on multistep reheating regime, are 510 MPa, 446 MPa and 17.5% respectively. These values are superior to those of the products manufactured with the conventional RAP route. As the results indicated, thixoforming could be conducted based on commercial extruded Al-Zn-Mg-Cu alloys, which has important practical significance.
10. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses
PubMed Central
Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan
2016-01-01
Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design. PMID:27230692
11. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses
Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan
2016-05-01
Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.
12. Microstructure and Mechanical Properties of AlN/Cu Brazed Joints
Su, Cherng-Yuh; Pan, C. T.; Lo, Min-Sheng
2014-09-01
In this study, the AlN/Cu bonding was explored using the brazing technique. During AlN/Cu brazing, the temperature was set at 800, 850, and 900 °C for 10, 20, 30, and 60 min, respectively. We studied the bonding mechanism, microstructure formation, and the mechanical characteristics of the bond. The reaction layer developed at the interface of AlN/Cu is observed to be TiN. The activation energy of TiN is about 149.91 kJ/mol. The reaction layer thickness is linearly dependent on the temperature and duration at 800 and 850 °C for 60 min and 900 °C for 30 min. However, the growth of the reactive layers decreases gradually at 900 °C when the duration changed from 30 to 60 min. The strength of the specimens with thickness ranging between 1 and 1.5 μm is 40-51 MPa.
13. Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles
Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.
2015-06-01
The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.
14. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses.
PubMed
Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C; Altman, Sidney; Schwarz, Udo D; Kyriakides, Themis R; Schroers, Jan
2016-05-27
Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.
15. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys
NASA Technical Reports Server (NTRS)
Wagner, John A.
1989-01-01
An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.
16. Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy
NASA Technical Reports Server (NTRS)
Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.
1991-01-01
Alloys in the Al-Cu-Li Ag-Mg subsystem were developed that exhibit desirable combinations of strength and ductility. These Weldalite (trademark) alloys, are unique for Al-Cu-Li alloys in that with or without a prior cold stretching operation, they obtain excellent strength-ductility combinations upon natural and artificial aging. This is significant because it enables complex, near-net shape products such as forgings and super plastically formed parts to be heat treated to ultra-high strengths. On the other hand, commercial extrusions, rolled plates and sheets of other Al-Cu-Li alloys are typically subjected to a cold stretching operation before artificial aging to the highest strength tempers to introduce dislocations that provide low-energy nucleation sites for strengthening precipitates such as the T(sub 1) phase. The variation in yield strength (YS) with Li content in the near-peak aged condition for these Weldalite (trademark) alloys and the associated microstructures were examined, and the results are discussed.
17. Tensile Anisotropy of Cu/Al Clad Metals After Prestrain Using Digital Image Correlation
Sun, Tao; Liang, Jin; Guo, Xiang; Li, Lei-gang
2013-12-01
A dimensional deformation measurement system (XJTUDIC/VS) based on digital image correlation was employed to measure the deformation and strain field of Cu/Al clad metals made using the explosive welding technique. An extensometer with a gage length of 50 mm was used during the Q235 tensile test to verify the strain measurement accuracy of the system. The results demonstrate that the accuracy of the XJTUDIC/VS system is ≥0.5%, which is very close to that of the extensometer. The anisotropy of Cu/Al clad metals under uniaxial tension after 0, 1.5, 2.5, and 4.5% prestrain was investigated. With an increase in strain, the true stress-strain curve varied at different directions in the same prestrains. The strain hardening rate, r value (changes from 0.1 to 0.9), and n value (changes from 0.25 to 0.35) all strongly depended on loading directions and prestrains. The linear relations between longitudinal strain and transverse strain were also influenced by tensile directions and prestrains. Cu/Al clad metals generally presented strong anisotropy.
18. Microstructural Evolution and Fracture Behavior of Friction-Stir-Welded Al-Cu Laminated Composites
Beygi, R.; Kazeminezhad, Mohsen; Kokabi, A. H.
2014-01-01
In this study, we attempt to characterize the microstructural evolution during friction stir butt welding of Al-Cu-laminated composites and its effect on the fracture behavior of the joint. Emphasis is on the material flow and particle distribution in the stir zone. For this purpose, optical microscopy and scanning electron microscopy (SEM) images, energy-dispersive spectroscopy EDS and XRD analyses, hardness measurements, and tensile tests are carried out on the joints. It is shown that intermetallic compounds exist in lamellas of banding structure formed in the advancing side of the welds. In samples welded from the Cu side, the banding structure in the advancing side and the hook formation in the retreating side determine the fracture behavior of the joint. In samples welded from the Al side, a defect is formed in the advancing side of the weld, which is attributed to insufficient material flow. It is concluded that the contact surface of the laminate (Al or Cu) with the shoulder of the FSW tool influences the material flow and microstructure of welds.
19. Energetic initiators with narrow firing thresholds using Al/CuO Schottky junctions
Wang, Feng; Zhu, Peng; Li, Jie; Hu, Bo; Shen, Ruiqi; Ye, Yinghua
2016-07-01
We designed and prepared Schottky-junction-based Al/CuO energetic initiators with narrow firing thresholds according to Schottky barrier theory. Using various characterization methods, we preliminarily investigated the electrical breakdown property, withstand strike current ability, and multiple-firing performance of the energetic initiators. The breakdown voltage of the Al/CuO Schottky junction was ~8 V; and electrical breakdown in the initiators occurred one by one rather than simultaneously. The withstand strike current ability of the initiator mainly depended on the heat capacity of its ceramic plug when the electrical stimulus is more than ~8 V, its breakdown voltage. The ceramic plug can absorb heat from the initiator chip, letting the initiator withstand a constant current of 0.5 A for 20 s. More importantly, the initiators might be able to withstand hard electromagnetic interference by coupling the multiple-firing performance with an out-of-line slider in the explosive train. This knowledge of the characteristics of Schottky-junction-based Al/CuO energetic initiators will help in preparing highly insensitive, efficient initiating explosive devices for weapon systems.
20. Crystal structure of 1/0-2/1-1/0 Cu-Al-Sc approximant
Ishimasa, Tsutomu; Hirao, Arina; Honma, Takahiro; Mihalkovič, Marek
2011-07-01
The new crystal structure of an orthorhombic phase formed at the alloy composition Cu48.1Al36.4Sc15.5 was analyzed by means of the Rietveld method using synchrotron radiation diffraction data. The starting model for this analysis was constructed theoretically using the so-called 'cell constrained melt-quenching technique'. The space group of the final model is Cmmm, and the unit cell includes 49.0 Cu, 39.0 Al and 16.0 Sc atoms. The lattice parameters are a = 8.337(4) Å, b = 22.02(1) Å and c = 8.305(4) Å, which are related to the six-dimensional lattice parameter, a 6D = 6.959 Å, of the corresponding Cu-Al-Sc icosahedral quasicrystal as 1/0, 2/1 and 1/0 approximations, respectively. The characteristics of the structure can be understood as a framework consisting of Sc atoms, which is regarded as a tiling of five local structural units; the largest is an icosahedron similar to that included in the Tsai-type quasicrystal. The second exhibits structural similarity to a Mg2Zn11-type crystal and the third is an octahedron.
1. Numerical Simulation of Residual Stress in an Al-Cu Alloy Block During Quenching and Aging
Dong, Ya-Bo; Shao, Wen-Zhu; Lu, Liang-Xing; Jiang, Jian-Tang; Zhen, Liang
2015-12-01
In this study, residual stresses after different quenching and aging processes of Al-Cu forged blocks were investigated by numerical simulation method and experimental measurements. An iterative zone-based heat transfer calculation was coupled with the hyperbolic sine-type constitutive model to simulate the residual stress during quenching process. The simulation results were compared with experiment data using both x-ray diffraction and crack compliance methods. The simulation results were in good agreement with the experimental measurements with around 9-13% deviation at the largest. Residual stress reduction can be achieved by decreasing the cooling rate during quenching. Quenching in water with different temperatures of 60, 80, and 100 °C resulted in the maximum compressive residual stress reduction of approximately 28.2, 75.7, and 88.9%, respectively, in Al-Cu alloy samples. When quenched in 10, 20, and 30% PAG solution, the reduction of maximum compressive residual stress in Al-Cu alloy samples was approximately 35.1, 47.8, and 53.2%, respectively. In addition, in order to study the amount of residual stress relief after aging treatments, aging treatments at 140 and 170 °C for different times were also studied. Aging treatment used to obtain the peak-aged (T6) and overaged (T7) condition produces only about 22.5 to 34.7% reduction in residual stresses.
2. Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles
SciTech Connect
Agrawal, Shraddha Parveen, Azra; Naqvi, A. H.
2015-06-24
The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.
3. A comprehensive energy approach to predict fatigue life in CuAlBe shape memory alloy
Sameallah, S.; Legrand, V.; Saint-Sulpice, L.; Kadkhodaei, M.; Arbab Chirani, S.
2015-02-01
Stabilized dissipated energy is an effective parameter on the fatigue life of shape memory alloys (SMAs). In this study, a formula is proposed to directly evaluate the stabilized dissipated energy for different values of the maximum and minimum applied stresses, as well as the loading frequency, under cyclic tensile loadings. To this aim, a one-dimensional fully coupled thermomechanical constitutive model and a cycle-dependent phase diagram are employed to predict the uniaxial stress-strain response of an SMA in a specified cycle, including the stabilized one, with no need of obtaining the responses of the previous cycles. An enhanced phase diagram in which different slopes are defined for the start and finish of a backward transformation strip is also proposed to enable the capture of gradual transformations in a CuAlBe shape memory alloy. It is shown that the present approach is capable of reproducing the experimental responses of CuAlBe specimens under cyclic tensile loadings. An explicit formula is further presented to predict the fatigue life of CuAlBe as a function of the maximum and minimum applied stresses as well as the loading frequency. Fatigue tests are also carried out, and this formula is verified against the empirically predicted number of cycles for failure.
4. Properties of Cu(In,Ga,Al)Se{sub 2} thin films fabricated by magnetron sputtering
SciTech Connect
Hameed, Talaat A.; Cao, Wei; Mansour, Bahiga A.; Elzawaway, Inas K.; Abdelrazek, El-Metwally M.; Elsayed-Ali, Hani E.
2015-05-15
Cu(In,Ga,Al)Se{sub 2} (CIGAS) thin films were studied as an alternative absorber layer material to Cu(In{sub x}Ga{sub 1−x})Se{sub 2}. CIGAS thin films with varying Al content were prepared by magnetron sputtering on Si(100) and soda-lime glass substrates at 350 °C, followed by postdeposition annealing at 520 °C for 5 h in vacuum. The film composition was measured by an electron probe microanalyzer while the elemental depth profiles were determined by secondary ion mass spectrometry. X-ray diffraction studies indicated that CIGAS films are single phase with chalcopyrite structure and that the (112) peak clearly shifts to higher 2θ values with increasing Al content. Scanning electron microscopy images revealed dense and well-defined grains, as well as sharp CIGAS/Si(100) interfaces for all films. Atomic force microscopy analysis indicated that the roughness of CIGAS films decreases with increasing Al content. The bandgap of CIGAS films was determined from the optical transmittance and reflectance spectra and was found to increase as Al content increased.
5. A comparable study of structural and electrical transport properties of Al and Cu nanowires using first-principle calculations
SciTech Connect
Gao, N.; Li, J. C. E-mail: [email protected]; Jiang, Q. E-mail: [email protected]
2013-12-23
The structural and quantum transport properties of Al and Cu nanowires with diameters up to 3.6 nm are studied using density functional theory combined with Landauer formalism. Contrary to the classical electronic behavior, the conductance of Al wires is larger than that of Cu. This is mainly attributed to the larger contribution of conductance channels from Al-3p, which is determined by the chemical nature. Meanwhile, the stronger axial contraction of Al wires plays a minor role to conductance. This makes Al wires possible candidate interconnects in integrated circuits.
6. Nuclear excitation functions of proton-induced reactions (Ep = 35-90 MeV) from Fe, Cu, and Al
Graves, Stephen A.; Ellison, Paul A.; Barnhart, Todd E.; Valdovinos, Hector F.; Birnbaum, Eva R.; Nortier, Francois M.; Nickles, Robert J.; Engle, Jonathan W.
2016-11-01
Fe, Cu, and Al stacked foils were irradiated by 90 MeV protons at the Los Alamos Neutron Science Center's Isotope Production Facility to measure nuclear cross sections for the production of medically relevant isotopes, such as 52gMn, 54Mn, 48Cr, 55Co, 58mCo and 57Ni. The decay of radioactive isotopes produced during irradiation was monitored using high-purity germanium gamma spectroscopy over the months following irradiation. Proton fluence was determined using the natAl(p,x)22Na, natCu(p,x)62Zn natCu(p,x)65Zn, and natCu(p,x)56Co monitor reactions. Calculated cross sections were compared against literature values and theoretical TALYS predictions. Notably this work includes the first reported independent cross section measurements of natCu(p,x)58mCo and natCu(p,x)58gCo.
7. High-temperature wear and oxidation behaviors of TiNi/Ti2Ni matrix composite coatings with TaC addition prepared on Ti6Al4V by laser cladding
Lv, Y. H.; Li, J.; Tao, Y. F.; Hu, L. F.
2017-04-01
TiNi/Ti2Ni matrix composite coatings were produced on Ti6Al4V surfaces by laser cladding the mixed powders of Ni-based alloy and different contents of TaC (0, 5, 10, 15, 20, 30 and 40 wt.%). Microstructures of the coatings were investigated. High-temperature wear tests of the substrate and the coatings were carried out at 600 °C in air for 30 min. High-temperature oxidation tests of the substrate and the coatings were performed at 1000 °C in air for 50 h. Wear and oxidation mechanisms were revealed in detail. The results showed that TiNi/Ti2Ni as the matrix and TiC/TiB2/TiB as the reinforcements are the main phases of the coatings. The friction coefficients of the substrate and the coatings with different contents of TaC were 0.431 (the substrate), 0.554 (0 wt.%), 0.486 (5 wt.%), 0.457 (10 wt.%), 0.458 (15 wt.%), 0.507 (20 wt.%), 0.462 (30 wt.%) and 0.488 (40 wt.%). The wear rates of the coatings were decreased by almost 83%-98% than that of the substrate and presented a decreasing tendency with increasing TaC content. The wear mechanism of the substrate was a combination of serious oxidation, micro-cutting and brittle debonding. For the coatings, oxidation and slight scratching were predominant during wear, accompanied by slight brittle debonding in partial zones. With the increase in content of TaC, the oxidation film better shielded the coatings from destruction due to the effective friction-reducing role of Ta2O5. The oxidation rates of the substrate and the coatings with different contents of TaC at 1000 °C were 12.170 (the substrate), 5.886 (0 wt.%), 4.937 (5 wt.%), 4.517 (10 wt.%), 4.394 (15 wt.%), 3.951 (20 wt.%), 4.239 (30 wt.%) and 3.530 (40 wt.%) mg2 cm-4 h-1, respectively. The oxidation film formed outside the coating without adding TaC was composed of TiO2, NiO, Cr2O3, Al2O3 and SiO2. When TaC was added, Ta2O5 and TaC were also detected, which effectively improved the oxidation resistance of the coatings. The addition of TaC contributed to the
8. TA Collaborations
ERIC Educational Resources Information Center
Diefendorf, Martha
2010-01-01
This paper highlights several current collaborative activities of the National Early Childhood Technical Assistance Center (NECTAC). There are many specific examples of TA (Technical Assistance) collaborations that take place on a regular basis; the seven examples presented here were selected to represent different types of collaboration. The…
9. Lattice Dynamical Properties and Elastic Constants of the Ternary Chalcopyrite Compounds CuAlS2, CuGaS2, CuInS2, and AgGaS2
2017-02-01
Lattice dynamics calculations have been performed for ternary chalcopyrite compounds CuAlS2, CuGaS2, CuInS2, and AgGaS2 using the proposed theoretical model. This model is applied to study the zone-centre (GAMMA = 0) phonon frequencies of CuAlS2, CuGaS2, CuInS2, and AgGaS2. The interatomic interactions up to third nearest neighbours were calculated. The calculated zone-centre phonon frequencies are found to be in very good agreement with observed and previous calculated data available in the literature. Single crystal elastic constants and related properties for these materials were also calculated and compared with the available data in the scientific literature.
10. Hydrogen purification for fuel cell using CuO/CeO 2-Al 2O 3 catalyst
Maciel, Cristhiane Guimarães; Profeti, Luciene Paula Roberto; Assaf, Elisabete Moreira; Assaf, José Mansur
CuO/CeO 2, CuO/Al 2O 3 and CuO/CeO 2-Al 2O 3 catalysts, with CuO loading varying from 1 to 5 wt.%, were prepared by the citrate method and applied to the preferential oxidation of carbon monoxide in a reaction medium containing large amounts of hydrogen (PROX-CO). The compounds were characterized ex situ by X-ray diffraction, specific surface area measurements, temperature-programmed reduction and temperature-programmed reduction of oxidized surfaces; XANES-PROX in situ experiments were also carried out to study the copper oxidation state under PROX-CO conditions. These analyses showed that in the reaction medium the Cu 0 is present as dispersed particles. On the ceria, these metallic particles are smaller and more finely dispersed, resulting in a stronger metal-support interaction than in CuO/Al 2O 3 or CuO/CeO 2-Al 2O 3 catalysts, providing higher PROX-CO activity and better selectivity in the conversion of CO to CO 2 despite the greater BET area presented by samples supported on alumina. It is also shown that the lower CuO content, the higher metal dispersion and consequently the catalytic activity. The redox properties of the ceria support also contributed to catalytic performance.
11. Effect of [Al] and [In] molar ratio in solutions on the growth and microstructure of electrodeposition Cu(In,Al)Se2 films
Huang, Kuo-Chan; Liu, Chien-Lin; Hung, Pin-Kun; Houng, Mau-Phon
2013-05-01
In this paper, the cyclic voltammetric studies were used to realize the element's reduction potential and chemical reaction mechanism for presuming the formation routes of quaternary Cu(In,Al)Se2 crystals. Thereafter, the prior adjustment of deposited potential from -0.6 V to -1.0 V can be identified a suitable potential as co-electrodeposition. The material characteristics of Cu(In,Al)Se2 films are dominated by the percentage of aluminum content. Thus, the influence of aluminum and indium concentrations in solutions on the percentage composition, surface morphology, structural and crystal properties, and optical energy band gap of Cu(In,Al)Se2 films were investigated. Energy dispersive X-ray spectroscopy (EDS) indicated that the ratio of Al to (Al + In) in Cu(In,Al)Se2 films varied from 0.21 to 0.42 when adjusting aluminum and indium concentrations in solutions. Scanning electron microscopy (SEM) shows that the surface morphology changed from round-like structures into cauliflower-like structures and became rough when the aluminum concentration increased and indium concentration decreased in solutions. X-ray diffraction (XRD) patterns revealed three preferred growth orientations along the (1 1 2), (2 0 4/2 2 0), and (1 1 6/3 1 2) planes for all species. The (αhυ)2 versus hυ plots (UV-Visible) shows that the optical energy band gap of the Cu(In,Al)Se2 films can be successfully controlled from 1.17 eV to 1.48 eV by adjusting the aluminum and indium concentrations. Furthermore, the shift of the (1 1 2) peak in the XRD patterns and variation of optical band gap are evidence that the incorporation of aluminum atoms into the crystallitic CuInSe2 forms Cu(In,Al)Se2 crystals.
12. Effect of Substitution (Ta, Al, Ga) on the Conductivity of Li7La3Zr2O12
DTIC Science & Technology
2012-01-30
13] Y. Li, C.-A. Wang, H. Xie, J. Cheng, J.B. Goodenough , Electrochem. Commun. 13 (2011) 1289. J.L. Allen et al. / Journal of Power Sources 206 (2012...Ionics 28 (1998) 862. [17] Y. Li, C. Sun, J.B. Goodenough , Chem. Mater. 23 (2011) 2292. [18] J.M. Amarilla, B. Casal, E. Ruiz-Hitzky, J. Mater. Chem
13. Precipitation of a new platelet phase during the quenching of an Al-Zn-Mg-Cu alloy
PubMed Central
Zhang, Yong; Weyland, Matthew; Milkereit, Benjamin; Reich, Michael; Rometsch, Paul A.
2016-01-01
A previously undescribed high aspect ratio strengthening platelet phase, herein named the Y-phase, has been identified in a commercial Al-Zn-Mg-Cu alloy. Differential scanning calorimetry indicates that this phase only precipitates at temperature and cooling rate of about 150–250 °C and 0.05–300 K/s, respectively. This precipitate is shown to be responsible for a noticeable improvement in mechanical properties. Aberration corrected scanning transmission electron microscopy demonstrates the minimal thickness (~1.4 nm) precipitate plates are isostructural to those of the T1 (Al2CuLi) phase observed in Al-Cu-Li alloys. Low voltage chemical analysis by energy dispersive X-ray spectroscopy and electron energy loss spectroscopy gives evidence of the spatial partitioning of the Al, Cu and Zn within the Y-phase, as well as demonstrating the incorporation of a small amount of Mg. PMID:26979123
14. Evolution of atomic structure in Al75Cu25 liquid from experimental and ab initio molecular dynamics simulation studies.
PubMed
Xiong, L H; Yoo, H; Lou, H B; Wang, X D; Cao, Q P; Zhang, D X; Jiang, J Z; Xie, H L; Xiao, T Q; Jeon, S; Lee, G W
2015-01-28
X-ray diffraction and electrostatic levitation measurements, together with the ab initio molecular dynamics simulation of liquid Al(75)Cu(25) alloy have been performed from 800 to 1600 K. Experimental and ab initio molecular dynamics simulation results match well with each other. No abnormal changes were experimentally detected in the specific heat capacity over total hemispheric emissivity and density curves in the studied temperature range for a bulk liquid Al(75)Cu(25) alloy measured by the electrostatic levitation technique. The structure factors gained by the ab initio molecular dynamics simulation precisely coincide with the experimental data. The atomic structure analyzed by the Honeycutt-Andersen index and Voronoi tessellation methods shows that icosahedral-like atomic clusters prevail in the liquid Al(75)Cu(25) alloy and the atomic clusters evolve continuously. All results obtained here suggest that no liquid-liquid transition appears in the bulk liquid Al(75)Cu(25) alloy in the studied temperature range.
15. Hydrogen embrittlement of aged and retrogressed-reaged Al-Li-Cu-Mg alloys
SciTech Connect
Thakur, C.; Balasubramaniam, R.
1997-04-01
The hydrogen embrittlement (HE) of Al-2.30 Li-1.24 Cu-0.80 Mg-0.12 Zr and Al-1.90 Li-1.80 Cu-1 Mg-0.09 Zr alloys in different artificial aging tempers and after retrogression and reaging (RRA) treatments has been investigated by tensile testing hydrogen precharged specimens. The influence of RRA and hydrogen charging on the dislocation structure was studied by TEM. The under-aged temper was the most susceptible while the peak-aged temper was the most resistant to HE. The RRA treatment improved the HE resistance of all the tempers. This has been attributed to the reduction in dislocation density upon retrogression and reaging. The alloy with the lower Li content exhibited improved HE resistance. Flat fractographic features near the surface of the hydrogen charged specimen have been correlated to the depth of hydrogen penetration. The formation of LiAlH{sub 4} and LiH in hydrogen charged Al-Li alloys has been confirmed by X-ray diffraction studies. The hydrogen-dislocation interaction and hydride cracking mechanisms of HE have been addressed.
16. Solar-blind ultraviolet photodetector based on (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 single crystal
Du, Jian-yu; Ge, Chen; Xing, Jie; Li, Jian-kun; Jin, Kui-juan; Yang, Jing-ting; Guo, Hai-zhong; He, Meng; Wang, Can; Lu, Hui-bin; Yang, Guo-zhen
2017-03-01
A solar-blind ultraviolet photodetector based on perovskite (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 (LSAT) single crystal has been fabricated. The Deep Ultra Violet (DUV)/Ultra Violet (UV) (200 versus 290 nm) ratio is more than three orders of magnitude under the applied bias voltage 200 V. Under illumination at 200 nm, the responsivity of this ultraviolet photodetector reaches 4 mA/W at 200 V bias. The corresponding quantum efficiency and detectivity are 2.76% and 1×1011 cmṡHz0.5/W, respectively. The ultrafast response with a rise time of 563 ps and full width half maximum (FWHM) of 1.085 ns is obtained. The high sensitivity, ultrafast response speed, and good signal-to-noise ratio demonstrate that the LSAT photodetector could be a promising candidate as the solar-blind ultraviolet photodetector.
17. H2 dissociation on γ-Al2O3 supported Cu/Pd atoms: A DFT investigation
Wang, Hongtao; Chen, Lijuan; Lv, Yongkang; Ren, Ruipeng
2014-01-01
The density functional theory (DFT) was applied to investigate the promotion effects of single Cu and Pd atoms deposition on γ-Al2O3 surface for the adsorption and dissociation of H2 molecule, which is of importance for many catalysis reactions. Due to its strong Lewis acidity, the tri-coordinated surface Al site was identified to be the most preferable site for both Cu and Pd location. The inner surface electrons rearrangement from O to Al of alumina was found to be a key factor to stabilize the Cu/Pd adsorption configurations, rather than the total electrons transfer between Cu/Pd and the surface. It was found that the supported Cu and Pd atoms are more active for H2 dissociation than the clean γ-Al2O3 surface. The supported Pd is more active than Cu for H2 dissociation. In addition, the metal-support interaction of the γ-Al2O3 supported Cu/Pd atoms are more favored than the metal-metal interaction of the metal clusters for the H2 dissociated adsorption.
18. Interfacial Reactions Between ZnAl(Ge) Solders on Cu and Ni Substrates
Rautiainen, Antti; Vuorinen, Vesa; Paulasto-Kröckel, Mervi
2017-04-01
Reactions between zinc-aluminum-germanium solder and copper/nickel substrates were investigated after 30 min of soldering at 420°C that simulates a wafer-level bonding process, and the results were compared to a eutectic zinc-aluminum solder. The ZnAlGe system (81.4 at.% Zn, 13.1 at.% Al, 5.5 at.% Ge) was selected in order to decrease the eutectic temperature of the ZnAleut (88.7 at.% Zn, 11.3 at.% Al) for high-temperature lead-free solder applications. In addition, a standard high temperature storage test at 150°C was performed up to 3000 h in order to investigate the evolution of the interconnection microstructures. Extensive copper dissolution was discovered during the soldering process. Germanium did not participate in any of the interfacial reactions on a copper substrate. On a nickel substrate, rapid formation of intermetallic compounds was discovered with both solders, and all the aluminum from the 500 μm thick solder was consumed by the formation of the Al3Ni2 phase during bonding. Germanium was observed to dissolve in the Al3Ni2 phase, but the addition of germanium to the solder was not found to affect markedly the interfacial microstructure. Based on the results, isothermal sections at 150°C of Al-Cu-Zn and Al-Ni-Zn systems are presented with superimposed diffusion paths.
19. Nanomechanical properties, wear resistance and in-vitro characterization of Ta2O5 nanotubes coating on biomedical grade Ti-6Al-4V.
PubMed
Sarraf, Masoud; Razak, Bushroa Abdul; Nasiri-Tabrizi, Bahman; Dabbagh, Ali; Kasim, Noor Hayaty Abu; Basirun, Wan Jefrey; Bin Sulaiman, Eshamsul
2017-02-01
Tantalum pentoxide nanotubes (Ta2O5 NTs) can dramatically raise the biological functions of different kinds of cells, thus have promising applications in biomedical fields. In this study, Ta2O5 NTs were prepared on biomedical grade Ti-6Al-4V alloy (Ti64) via physical vapor deposition (PVD) and a successive two-step anodization in H2SO4: HF (99:1)+5% EG electrolyte at a constant potential of 15V. To improve the adhesion of nanotubular array coating on Ti64, heat treatment was carried out at 450°C for 1h under atmospheric pressure with a heating/cooling rate of 1°Cmin(-)(1). The surface topography and composition of the nanostructured coatings were examined by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS), to gather information about the corrosion behavior, wear resistance and bioactivity in simulated body fluids (SBF). From the nanoindentation experiments, the Young's modulus and hardness of the 5min anodized sample were ~ 135 and 6GPa, but increased to ~ 160 and 7.5GPa, respectively, after annealing at 450°C. It was shown that the corrosion resistance of Ti64 plates with nanotubular surface modification was higher than that of the bare substrate, where the 450°C annealed specimen revealed the highest corrosion protection efficiency (99%). Results from the SBF tests showed that a bone-like apatite layer was formed on nanotubular array coating, as early as the first day of immersion in simulated body fluid (SBF), indicating the importance of nanotubular configuration on the in-vitro bioactivity.
20. Vibrational states on vicinal surfaces of Al, Ag, Cu and Pd
Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.
1998-10-01
We present the calculation of vibrational modes and lattice relaxation for the (110), (211), (311), (511), (331) and (221) surfaces of Al, Ag, Cu and Pd. The surface phonon frequencies and polarizations are obtained for relaxed and unrelaxed surfaces using embedded atom model potentials. On all surfaces studied step-localized vibrational modes and surface states localized on terrace atoms are found. It is shown that as the terrace width increases so does the number of surface phonons. It is found that interlayer relaxation leads to a shift in the frequencies of the surface states and to a change in the number and localization. In particular, it may cause the appearance or disappearance of step modes. It is shown that the character of relaxation on vicinal surfaces is determined by the number of atoms on a terrace. A comparison of the results with the available experimental data for the Al(221), Cu(211), and Cu(511) surfaces indicates that there is a good agreement with the experimental data.
1. The influence of Cu, Al, or Fe on the insulating capacity of CF3I
Xiao, Song; Cressault, Yann; Zhang, Xiaoxing; Teulet, Philippe
2016-12-01
SF6 is widely used in electrical equipment as an insulating medium. However, SF6 is a serious greenhouse gas. CF3I is considered as one of its potential alternatives. This study verifies whether free metal particle (Cu, Al, or Fe) defects adversely affect CF3I insulation and investigates the incidence from different types and numbers of metal particles. This study is also devoted to calculating specific heat at constant pressure and electrical conductivity of CF3I-metal mixtures. The calculation results prove that with the increase of metal ions, temperature rises faster in the CF3I-Cu plasma or in the CF3I-Fe plasma than in the CF3I plasma without metal absorbing the same energy. The fast development of ionization can promote the increase of free electrons and the rise of electric conductivity. On the basis of the experiments and theoretical analysis, the influence of Cu and Al on the insulating capacity of CF3I is greater than that of Fe.
2. Strengthening TiN diffusion barriers for Cu metallization by lightly doping Al
Yang, L. C.; Hsu, C. S.; Chen, G. S.; Fu, C. C.; Zuo, J. M.; Lee, B. Q.
2005-09-01
Thin films of Ti1-xAlxN were deposited on (100) Si by ultrahigh-vacuum dual-target reactive sputtering, and the impact of lightly doping Al of x as small as 0.09 on altering the films's microstructure upon thermal annealing, and hence the performance of the films (40nm thick) as diffusion barriers for Cu metallization was evaluated. The results of transmission electron microscopy, Rutherford backscattering spectroscopy, and grazing-incidence x-ray diffraction show that the TiN barrier layer gives the commonly observed voided, columnar grains composed of 5nm sized subgrains. Upon annealing, the subgrains tend to coalesce into 20nm sized equiaxed grains full of crystalline defects, initiating an inward penetration of Cu and a partial dissociation of TiN, transforming themselves, respectively, into pyramidal (or columnar) Cu3Si precipitates and a dendritic Ti5Si3 layer just after 550°C, 10min annealing. However, the lightly doped Al not only overrides the tendency to form intercolumnar voids inherent in sputter deposition by self-shadowing and statistical roughening, but also substantially enhances the microstructural and thermochemical stability, hence significantly improving barrier property, as evidenced from an annealing test at an elevated temperature (600°C) for a prolonged period of 30min.
3. Development of Sn-Ag-Cu-X Solders for Electronic Assembly by Micro-Alloying with Al
SciTech Connect
Boesenberg, Adam; Anderson, Iver; Harringa, Joel
2012-03-10
Of Pb-free solder choices, an array of solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic (T eut = 217°C) composition have emerged with potential for broad use, including ball grid array (BGA) joints that cool slowly. This work investigated minor substitutional additions of Al (<0.25 wt.%) to Sn-3.5Ag-0.95Cu (SAC3595) solders to promote more consistent solder joint microstructures and to avoid deleterious product phases, e.g., Ag3Sn “blades,” for BGA cooling rates, since such Al additions to SAC had already demonstrated excellent thermal aging stability. Consistent with past work, blade formation was suppressed for increased Al content (>0.05Al), but the suppression effect faded for >0.20Al. Undercooling suppression did not correlate specifically with blade suppression since it became significant at 0.10Al and increased continuously with greater Al to 0.25Al. Surprisingly, an intermediate range of Al content (0.10 wt.% to 0.20 wt.% Al) promoted formation of significant populations of 2-μm to 5-μm faceted Cu-Al particles, identified as Cu33Al17, that clustered at the top of the solder joint matrix and exhibited extraordinary hardness. Clustering of Cu33Al17 was attributed to its buoyancy, from a lower density than Sn liquid, and its early position in the nucleation sequence within the solder matrix, permitting unrestricted migration to the top interface. Joint microstructures and implications for the full nucleation sequence for these SAC + Al solder joints are discussed, along with possible benefits from the clustered particles for improved thermal cycling resistance.
4. Spin glass behavior in frustrated quantum spin system CuAl2O4 with a possible orbital liquid state
Nirmala, R.; Jang, Kwang-Hyun; Sim, Hasung; Cho, Hwanbeom; Lee, Junghwan; Yang, Nam-Geun; Lee, Seongsu; Ibberson, R. M.; Kakurai, K.; Matsuda, M.; Cheong, S.-W.; Gapontsev, V. V.; Streltsov, S. V.; Park, Je-Geun
2017-04-01
CuAl2O4 is a normal spinel oxide having quantum spin, S = 1/2 for Cu2+. It is a rather unique feature that the Cu2+ ions of CuAl2O4 sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl2O4 shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, there is a peak at ~2.3 K in the heat capacity, which shifts towards a higher temperature with magnetic fields. On the other hand, there is no evidence of new superlattice peaks in the high-resolution neutron powder diffraction data when cooled from 40 to 0.4 K. This implies that there is no long-ranged magnetic order down to 0.4 K, thus confirming a spin glass-like ground state for CuAl2O4. Interestingly, there is no sign of structural distortion either although Cu2+ is a Jahn–Teller active ion. Thus, we claim that an orbital liquid state is the most likely ground state in CuAl2O4. Of further interest, it also exhibits a large frustration parameter, f = |θ CW/T m| ~ 67, one of the largest values reported for spinel oxides. Our observations suggest that CuAl2O4 should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state.
5. Spin glass behavior in frustrated quantum spin system CuAl 2 O 4 with a possible orbital liquid state
DOE PAGES
Nirmala, R.; Jang, Kwang-Hyun; Sim, Hasung; ...
2017-02-15
CuAl2O4 is a normal spinel oxide having quantum spin, S = 1/2 for Cu2+. It is a rather unique feature that the Cu2+ ions of CuAl2O4 sit at a tetrahedral position, not like the usual octahedral position for many oxides. At low temperatures, it exhibits all the thermodynamic evidence of a quantum spin glass. For example, the polycrystalline CuAl2O4 shows a cusp centered at ~2 K in the low-field dc magnetization data and a clear frequency dependence in the ac magnetic susceptibility while it displays logarithmic relaxation behavior in a time dependence of the magnetization. At the same time, theremore » is a peak at ~2.3 K in the heat capacity, which shifts towards a higher temperature with magnetic fields. Conversely, there is no evidence of new superlattice peaks in the high-resolution neutron powder diffraction data when cooled from 40 to 0.4 K. This implies that there is no long-ranged magnetic order down to 0.4 K, thus confirming a spin glass-like ground state for CuAl2O4. Interestingly, there is no sign of structural distortion either although Cu2+ is a Jahn–Teller active ion. Therefore, we claim that an orbital liquid state is the most likely ground state in CuAl2O4. Of further interest, it also exhibits a large frustration parameter, f = |θ CW/T m| ~ 67, one of the largest values reported for spinel oxides. These observations suggest that CuAl2O4 should be a rare example of a frustrated quantum spin glass with a good candidate for an orbital liquid state.« less
6. Magnetic properties of Nd-Fe-Co(Cu)-Al-B amorphous alloys prepared by nonequilibrium techniques
Kumar, G.; Eckert, J.; Roth, S.; Löser, W.; Ram, S.; Schultz, L.
2002-03-01
The amorphous alloys Nd40Fe40Co5Al8B7, Nd57Fe20Co5Al10B8, and Nd57Fe20Cu5Al10B8 were prepared by copper mold casting, melt spinning, and mechanical alloying. Despite their similar x-ray diffraction patterns, samples display different magnetic and thermal behavior correlated with the method of preparation. The fully amorphous melt-spun ribbons exhibit relatively soft magnetic properties with coercivities ≈40 kA/m at room temperature and a Curie temperature (TC)≈474 K. Apparently only the mold-cast cylinders of 3 mm diameter show hard magnetic behavior with a coercivity in the range of 258-270 kA/m (depending on composition) and have approximately the same TC as that of the melt-spun ribbons. An additional magnetic transition at 585 K due to the presence of Nd2Fe14B phase in the case of Nd40Fe40Co5Al8B7 cast rod has been observed. Heat treatment above crystallization temperature in as-cast Nd57Fe20Co5Al10B8 and Nd57Fe20Cu5Al10B8 samples destroys the hard magnetic properties. In contrast, mechanically alloyed amorphous samples are soft magnetic with maximum coercivity up to 11 kA/m but show an entirely different TC≈680-740 K, which is rather characteristic of an Fe solid solution. The magnetic properties are discussed in terms of different local atomic environment and cluster sizes in amorphous samples prepared by different methods.
7. Stokes-Einstein relation and excess entropy in Al-rich Al-Cu melts
Pasturel, A.; Jakse, N.
2016-07-01
We investigate the conditions for the validity of the Stokes-Einstein relation that connects diffusivity to viscosity in melts using entropy-scaling relationships developed by Rosenfeld. Employing ab initio molecular dynamics simulations to determine transport and structural properties of liquid Al1-xCux alloys (with composition x ≤ 0.4), we first show that reduced self-diffusion coefficients and viscosities, according to Rosenfeld's formulation, scale with the two-body approximation of the excess entropy except the reduced viscosity for x = 0.4. Then, we use our findings to evidence that the Stokes-Einstein relation using effective atomic radii is not valid in these alloys while its validity can be related to the temperature dependence of the partial pair-excess entropies of both components. Finally, we derive a relation between the ratio of the self-diffusivities of the components and the ratio of their pair excess entropies.
8. Atomistic Modeling of Quaternary Alloys: Ti and Cu in NiAl
NASA Technical Reports Server (NTRS)
Bozzolo, Guillermo; Mosca, Hugo O.; Wilson, Allen W.; Noebe, Ronald D.; Garces, Jorge E.
2002-01-01
The change in site preference in NiAl(Ti,Cu) alloys with concentration is examined experimentally via ALCHEMI and theoretically using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Results for the site occupancy of Ti and Cu additions as a function of concentration are determined experimentally for five alloys. These results are reproduced with large-scale BFS-based Monte Carlo atomistic simulations. The original set of five alloys is extended to 25 concentrations, which are modeled by means of the BFS method for alloys, showing in more detail the compositional range over which major changes in behavior occur. A simple but powerful approach based on the definition of atomic local environments also is introduced to describe energetically the interactions between the various elements and therefore to explain the observed behavior.
9. Crystallization and nanoindentation behavior of a bulk Zr-Al-Ti-Cu-Ni amorphous alloy
SciTech Connect
Wang, J. G.; Choi, B. W.; Nieh, T. G.; Liu, C. T.
2000-03-01
The crystallization and nanoindentation behavior of a Zr-10Al-5Ti-17.9Cu-14.6Ni (at.%) bulk amorphous alloy (BAA) were studied. Resulting from the kinetic nature of phase transformation in multicomponent alloys, the crystallization path is complex. Despite the complexity of different crystallization paths, the main final crystallized product in the Zr-based BAA is Zr{sub 2}Cu. Young's modulus and hardness of the BAA were found to increase with an increase in annealing temperature. The observed mechanical properties were correlated with the microstructure of the material. Also, in the present paper, both the observed crystallization and nanoindentation behavior are compared with existing data. Zr-based BAAs exhibit a ratio of hardness to Young's modulus (H/E ratio) of about 1/10, suggesting the interatomic bonding in the alloys is close to being covalent. (c) 2000 Materials Research Society.
10. Crystallization from high temperature solutions of Si in Cu/Al solvent
DOEpatents
Ciszek, Theodore F.; Wang, Tihu
1996-01-01
A liquid phase epitaxy method for forming thin crystalline layers of device quality silicon having less than 3.times.10.sup.16 Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850.degree. to about 1100.degree. C. in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution.
11. Crystallization from high temperature solutions of Si in Cu/Al solvent
DOEpatents
Ciszek, T.F.; Wang, T.
1996-08-13
A liquid phase epitaxy method is disclosed for forming thin crystalline layers of device quality silicon having less than 3{times}10{sup 16} Cu atoms/cc impurity, comprising: preparing a saturated liquid solution of Si in a Cu/Al solvent at about 20 to about 40 at. % Si at a temperature range of about 850 to about 1100 C in an inert gas; immersing or partially immersing a substrate in the saturated liquid solution; super saturating the solution by lowering the temperature of the saturated solution; holding the substrate in the saturated solution for a period of time sufficient to cause Si to precipitate out of solution and form a crystalline layer of Si on the substrate; and withdrawing the substrate from the solution. 3 figs.
12. Investigation on compressive behavior of Cu-35Ni-15Al alloy at high temperatures
Li, Cong; Chen, Jian; Li, Wei; Hu, Yongle; Ren, Yanjie; Qiu, Wei; He, Jianjun; Chen, Jianlin
2014-09-01
Microstructures and mechanical properties of Cu-35Ni-15Al alloy in cast and porous states were studied by scanning electron microscopy and compression tests. The influence of porosity, deformation temperature and loading rate on mechanical properties of the two kinds of alloys was investigated. The results show that the as cast alloy and porous alloys have almost the same phase constitution: Cu rich phase, Ni rich phase and K intermetallics. The yield strength of porous alloys increases continuously with decreasing porosity, the relationship between porosity and yield stress follows Gibson-Ashby equation. With decreasing deformation temperature, the yield strength of as cast alloy and porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend. After compression, the microstructure of as cast alloy is more uniform, and porous alloys are more prone to have localized deformations.
13. Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors
In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the
14. Ion irradiation induced element-enriched and depleted nanostructures in Zr-Al-Cu-Ni metallic glass
SciTech Connect
Chen, H. C.; Liu, R. D.; Yan, L. E-mail: [email protected]; Zhou, X. T. E-mail: [email protected]; Cao, G. Q.; Wang, G.
2015-07-21
The microstructural evolution of a Zr-Al-Cu-Ni metallic glass induced by irradiation with Ar ions was investigated. Under ion irradiation, the Cu- and Ni-enriched nanostructures (diameter of 30–50 nm) consisted of crystalline and amorphous structures were formed. Further, Cu- and Ni-depleted nanostructures with diameters of 5–20 nm were also observed. The formation of these nanostructures can be ascribed to the migration of Cu and Ni atoms in the irradiated metallic glass.
15. Morphology and properties of a hybrid organic-inorganic system: Al nanoparticles embedded into CuPc thin film
SciTech Connect
Molodtsova, O. V.; Babenkov, S. V.; Aristova, I. M.; Vilkov, O. V.; Aristov, V. Yu.
2014-04-28
The evolution of the morphology and the electronic structure of the hybrid organic-inorganic system composed of aluminum nanoparticles (NPs) distributed in an organic semiconductor matrix—copper phthalocyanine (CuPc)—as a function of nominal aluminum content was studied by transmission electron microscopy and by photoemission spectroscopy methods. The aluminum atoms deposited onto the CuPc surface diffuse into the organic matrix and self-assemble to NPs in a well-defined manner with a narrow diameter distribution, which depends on the amount of aluminum that is evaporated onto the CuPc film. We find clear evidence of a charge transfer from Al to CuPc and we have been able to determine the lattice sites where Al ions sit. The finally at high coverage about 64 Å the formation of metallic aluminum overlayer on CuPc thin film takes place.
16. Combination of ToF-SIMS imaging and AFM to study the early stages of corrosion in Al-Cu thin films
SciTech Connect
Seyeux, A.; Missert, Nancy; Frankel, Gerald; Unocic, Kinga A; Klein, L. H.; Galtayries, A.; Marcus, P
2011-01-01
The pitting corrosion of Al-Cu thin film alloys was investigated using samples that were heat treated in air to form through-thickness Al2Cu particles within an Al-0.5%Cu matrix. Time-of-Flight SIMS (ToF-SIMS) analysis revealed Cu-rich regions 250 - 800 nm in lateral extent near the metal/oxide interface. Following exposure that generated pitting corrosion, secondary electron, secondary ion, and AFM images showed pits with size and density similar to those of the Cu-rich regions. The role of the Cu-rich regions is addressed.
17. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling
SciTech Connect
Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H.; Antusek, Andrej; Parlinska-Wojtan, Magdalena; Bissig, Vinzenz
2012-10-29
Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.
18. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an AL-Zn-Mg-(Cu) Alloy
SciTech Connect
Young, G A; Scully, J R
2002-04-09
Precipitation hardenable Al-Zn-Mg alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are used to increase HEAC resistance at the expense of strength but overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). Results show that overaging the copper bearing alloys both inhibits hydrogen ingress from oxide covered surfaces and decreases the apparent hydrogen diffusion rates in the metal.
19. Intrinsic fatigue crack growth rates for Al-Li-Cu-Mg alloys in vacuum
NASA Technical Reports Server (NTRS)
Slavik, D. C.; Blankenship, C. P., Jr.; Starke, E. A., Jr.; Gangloff, R. P.
1993-01-01
The influences of microstructure and deformation mode on inert environment intrinsic fatigue crack propagation were investigated for Al-Li-Cu-Mg alloys AA2090, AA8090, and X2095 compared to AA2024. The amount of coherent shearable delta-prime (Al3Li) precipitates and extent of localized planar slip deformation were reduced by composition (increased Cu/Li in X2095) and heat treatment (double aging of AA8090). Intrinsic growth rates, obtained at high constant K(max) to minimize crack closure and in vacuum to eliminate any environmental effect, were alloy dependent; da/dN varied up to tenfold based on applied Delta-K or Delta-K/E. When compared based on a crack tip cyclic strain or opening displacement parameter, growth rates were equivalent for all alloys except X2095-T8, which exhibited unique fatigue crack growth resistance. Tortuous fatigue crack profiles and large fracture surface facets were observed for each Al-Li alloy independent of the precipitates present, particularly delta-prime, and the localized slip deformation structure. Reduced fatigue crack propagation rates for X2095 in vacuum are not explained by either residual crack closure or slip reversibility arguments; the origin of apparent slip band facets in a homogeneous slip alloy is unclear.
20. Growth process of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} whiskers
SciTech Connect
Zhu Chengcai; Nai Xueying; Zhu Donghai; Guo Fengqin; Zhang Yongxing; Li Wu
2013-01-15
The reactions occurred and growth process in the preparation of copper aluminum borate (Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17}) whiskers based on flux method (Al{sub 2}(SO{sub 4}){sub 3}/CuSO{sub 4}/H{sub 3}BO{sub 3} as raw materials, K{sub 2}SO{sub 4} as flux) were investigated. The thermogravimetric and differential scanning calorimetry analysis (TG-DSC), inductively coupled plasma atomic emission spectrum analysis (ICP-AES) and X-ray diffraction analysis (XRD) results of reactants mixture quenched at various temperatures and phase diagrams of K{sub 2}SO{sub 4}-Al{sub 2}(SO{sub 4}){sub 3} system and B{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system showed that the reaction process proceeds through three steps: the formation and decomposition of two different kinds of potassium aluminum sulfate (K{sub 3}Al(SO{sub 4}){sub 3} and KAl(SO{sub 4}){sub 2}); the formation of aluminum borate (Al{sub 4}B{sub 2}O{sub 9}) and decomposition of copper sulfate (CuSO{sub 4}) and boric acid (H{sub 3}BO{sub 3}); growth and formation of copper aluminum borate (Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17}) whiskers. The scanning electron microscopy (SEM) analysis results indicated that morphology in growth of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} whiskers develops through three stages: nanoparticles, fan-shaped whiskers and agminate-needlelike whiskers. - Graphical abstract: The morphology in growth of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} whiskers develops through three stages: nanoparticles, fan-shaped whiskers and agminate-needlelike whiskers. Highlights: Black-Right-Pointing-Pointer Reaction process in the preparation of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} whiskers was researched systematically. Black-Right-Pointing-Pointer Crystal growth mechanism of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} whiskers was proposed by theory and experiments. Black-Right-Pointing-Pointer Properties of Cu{sub 2}Al{sub 6}B{sub 4}O{sub 17} were analyzed by instruments, such as TG-DSC, ICP-AES, XRD and SEM.
1. Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Al-Cu-Sn alloy
Bencze, L.; Milacic, R.; Jacimovic, R.; Zigon, D.; Mátyás, L.; Popovic, A.
2010-01-01
The vaporisation of a liquid Al-Cu-Sn system has been investigated at 1273-1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich-Kister-Muggianu (RKM) sub-regular solution model. Thirty-one different compositions (41 samples) have been examined at eight fixed copper mole fractions, XCu = 0.10, 0.20, 0.30, 0.333, 0.40, 0.50, 0.60 and 0.70. The ternary L-parameters, the thermodynamic activities and the thermodynamic functions of mixing have been evaluated using standard KEMS procedures. In addition, the same quantities were obtained from the measured ion intensity ratios of Al+ to Cu+, Al+ to Sn+ and Cu+ to Sn+ using a mathematical regression technique. The intermediate data obtained directly are the RKM ternary L-parameters that are, as a function of temperature, as follows:L(0)=(14270+/-1270)+(100.1+/-7.6)T-(11.77+/-0.93)T[thin space]ln(T);L(1)=(145600+/-9780)+(101.6+/-58.7)T-(15.56+/-7.14)T[thin space]ln(T);L(2)=(76730+/-1240)+(79.2+/-7.4)T-(15.69+/-0.91)T[thin space]ln(T). From the obtained ternary L-parameters the integral molar excess Gibbs energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies can be also determined. In addition, for comparison, for some compositions, the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs-Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained from the RKM model.
2. Hydrogenolysis of Glycerol to Propylene Glycol on Nanosized Cu-Zn-Al Catalysts Prepared Using Microwave Process.
PubMed
Kim, Dong Won; Ha, Sang Ho; Moon, Myung Jun; Lim, Kwon Taek; Ryu, Young Bok; Lee, Sun Do; Lee, Man Sig; Hong, Seong-Soo
2015-01-01
Cu-Zn-Al catalysts were prepared using microwave-assisted process and co-precipitation methods. The prepared catalysts were characterized by XRD, BET, XPS and TPD of ammonia and their catalytic activity for the hydrogenolysis of glycerol to propylene glycol was also examined. The XRD patterns of Cu/Zn/Al mixed catalysts show CuO and ZnO crystalline phase regardless of preparation method. The highest glycerol hydrogenolysis conversion is obtained with the catalyst having a Cu/Zn/Al ratio of 2:2:1. Hydrogen pre-reduction of catalysts significantly enhanced both glycerol conversions and selectivity to propylene glycol. The glycerol conversion increased with an increase of reaction temperature. However, the selectivity to propylene glycol increased with an increase of temperature, and then declined to 30.5% at 523 K.
3. Friction and Wear Characteristics of Cu-4Al Foil Bearing Coating at 25 and 650 degree C
NASA Technical Reports Server (NTRS)
Stanford, Malcolm K.; DellaCorte, Christopher
2004-01-01
The friction and wear performance of a Cu-4Al top foil coating has been investigated in Generation I foil air bearings. The copper alloy was applied by a novel deposition technique (ion diffusion) and the journal was coated with PS304, a plasma spray deposited high temperature composite solid lubricant coating. The ion diffusion coating process deposits a desirable smooth layer compared to other methods like cathodic arc deposition. The tribological performance of bearings with and without Cu-4Al foil coatings were evaluated through start-stop tests on an air bearing test rig at 25 and 650 C. The results indicate that the Cu-4Al assists during the initial break-in period, gives more stable friction performance with respect to temperature, and appears to prevent top foil wear at high temperature. The measured load capacity coefficient was 0.5, which was comparable to earlier testing of more advanced design Generation III bearings coated with standard cathodic arc deposited Cu-4Al. However, further studies are needed to determine if deeper penetration of the copper alloy into the foil would help make the transition in friction behavior from contact with the Cu-4Al coated foil to contact with the base foil material more gradual. Also, future work is recommended to assess the performance of ion diffusion coatings with different Cu-based alloy compositions and to investigate the effect the coating has on the elastic modulus of the foil material.
4. Thermal stability and crystallization kinetics of Cu-Zr-Al-Ag BMGs investigated with isothermal electrical resistance measurement
Wang, Li-Fang; Cui, Xiao; Zhang, Qi-Dong; Zu, Fang-Qiu
2014-07-01
The thermal stability and crystallization kinetics of the Cu x Zr84- x Al8Ag8 ( x = 42, 40, 38, and 36) bulk metallic glasses (BMGs) were studied by measurement of isothermal electrical-resistance. As the composition becomes richer in Zr, the longer incubation time at the same relative annealing temperature, and the larger local activation energy needed to achieve the same crystallized volume-fraction, indicate improved thermal stability, which resists crystallization. The improved thermal stability is attributed to a denser atomic random-stacking structure and larger negative heat-of-mixing. During isothermal annealing processes, the four BMGs exhibited the same nucleation mechanism, which is a decreasing rate of nucleation over time. However, the crystal growth mechanisms of the four BMGs are different. The crystallization of the Cu36Zr48Al8Ag8 and Cu38Zr46Al8Ag8 BMGs is interface-controlled growth, contrasting with diffusion-controlled growth for the Cu40Zr44Al8Ag8 and Cu42Zr42Al8Ag8 alloys. The different growth modes may be caused by fluctuations in composition due to changes in the quantity and distribution of Cu-rich and Ag-rich regions.
5. CuAlTe{sub 2} under high temperature: An ab initio approach
SciTech Connect
Sharma, Monika Singh, Poonam Kumari, Meena Verma, U. P.
2014-04-24
The structural properties of the ternary CuAlTe{sub 2} semiconductor are investigated using the full-potential linearized augmented plane wave plus local orbital (FP−LAPW+lo) method within the local density approximation in the frame of the density functional theory. Our calculated results for structural properties are in excellent agreement with experimental values in comparison to the previous theoretical results. Through the quasi - harmonic Debye model, we have obtained successfully the thermodynamic properties in the pressure range from 0 to 50 GPa and the temperature range from 0 to 1100 K.
6. The rate dependence of the saturation flow stress of Cu and 1100 Al
SciTech Connect
Preston, D.L.; Tonks, D.L.; Wallace, D.C.
1991-01-01
The strain-rate dependence of the saturation flow stress of OFHC Cu and 1100 Al from 10{sup {minus}3}s{sup {minus}1} to nearly to 10{sup 12}s{sup {minus}1} is examined. The flow stress above 10{sup 9}s{sup {minus}1} is estimated using Wallace's theory of overdriven shocks in metals. A transition to the power-law behavior {Psi} {approximately} {tau}{sub s}{sup 5} occurs at a strain rate of order 10{sup 5}s{sup {minus}1}. 10 refs., 2 figs.
7. A thermodynamic prediction for microporosity formation in aluminum-rich Al-Cu alloys
NASA Technical Reports Server (NTRS)
Poirier, D. R.; Yeum, K.; Maples, A. L.
1987-01-01
A computer model is used to predict the formation and degree of microporosity in a directionally solidified Al-4.5 wt pct Cu alloy, considering the interplay between solidification shrinkage and gas porosity. Macrosegregation theory is used to determine the local pressure within the interdendritic liquid. Results show interdendritic porosity for initial hydrogen contents in the 0.03-1 ppm range, and none below contents of 0.03. An increase in either the thermal gradient or the solidification rate is show to decrease the amount of interdendritic porosity.
8. Mobile Interfacial Microstructures in Single Crystals of Cu-Al-Ni Shape Memory Alloy
Seiner, Hanuš
2015-06-01
This paper summarizes the main properties of the microstructures formed during reverse (austenite → martensite) transitions in single crystals of the Cu-Al-Ni shape memory alloy, and discusses the relation between these properties and the mechanical stabilization effect. It is shown that all experimentally observed interfacial microstructures ( X- and λ-interfaces and their non-classical equivalents) are not local minimizers of the quasi-static energy, and their formation is probably governed by requirements on mobility and dissipation. This conclusion is supported by finite elements models, and acoustic emission measurements.
9. Physical, mechanical, and tribological properties of quasicrystalline Al-Cu-Fe coatings prepared by plasma spraying
Lepeshev, A. A.; Rozhkova, E. A.; Karpov, I. V.; Ushakov, A. V.; Fedorov, L. Yu.
2013-12-01
The physical, mechanical, and tribological properties of quasicrystalline coatings based on the Al65Cu23Fe12 alloy prepared by plasma spraying have been investigated. The specific features of the phase formation due to the competitive interactions of the icosahedral ψ and cubic β phases have been elucidated. A correlation between the microhardness and the content of the icosahedral phase in the coating has been determined. The decisive role of the quasicrystalline phase in the formation of high tribological characteristics of the coatings has been revealed and tested.
10. Transmission electron microscopy characterization of microstructural features of Al-Li-Cu alloys
NASA Technical Reports Server (NTRS)
Avalos-Borja, M.; Pizzo, P. P.; Larson, L. A.
1983-01-01
A transmission electron microscopy (TEM) examination of aluminum-lithium-copper alloys was conducted. The principal purpose is to characterize the nature, size, and distribution of stringer particles which result from the powder metallurgy (P/M) processing of these alloys. Microstructural features associated with the stringer particles are reported that help explain the stress corrosion susceptibility of the powder metallurgy-processed Al-Li-Cu alloys. In addition, matrix precipitation events are documented for a variety of heat treatments and process variations. Hot rolling is observed to significant alter the nature of matrix precipitation, and the observations are correlated with concomitant mechanical property variations.
11. Melt Cleanliness Comparison of Chlorine Fluxing and Ar Degassing of Secondary Al-4Cu
Çolak, Murat; Kayikci, Ramazan; Dispinar, Derya
2016-10-01
The treatment of liquid aluminum prior to casting typically consists of purging gas and/or fluxes through the melt. By the use of several chemicals during these operations, several environmental problems can occur. Therefore, in this study, the melt cleanliness of Al-4Cu secondary alloy was investigated by comparing the use of argon degassing with or without chlorine fluxing. Reduced pressure test was used to assess the melt quality. Highest quality melt was obtained by Ar degassing with preheated graphite lance without the need to use any chemicals.
12. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al Part II: Scale Microstructures
NASA Technical Reports Server (NTRS)
Raj, Sai V.
2008-01-01
The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. Details of the oxidation kinetics of these alloys were discussed in Part I. This paper analyzes the microstructures of the scale and its composition in an attempt to elucidate the oxidation mechanisms in these alloys. The scales formed on Cu-17%Cr specimens oxidized between 773 and 973 K consisted of external CuO and subsurface Cu2O layers. The total thickness of these scales varied from about 10 m at 773 K to about 450 m at 973 K. In contrast, thin scales formed on Cu-17%Cr-5%Al alloys oxidized between 773 and 1173 K. The exact nature of these scales could not be determined by x-ray diffraction but energy dispersive spectroscopy analyses were used to construct a scale composition map. Phenomenological oxidation mechanisms are proposed for the two alloys.
13. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al. Part 2; Scale Microstructures
NASA Technical Reports Server (NTRS)
Raj, S. V.
2008-01-01
The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. Details of the oxidation kinetics of these alloys were discussed in Part I. This paper analyzes the microstructures of the scale and its composition in an attempt to elucidate the oxidation mechanisms in these alloys. The scales formed on Cu-17%Cr specimens oxidized between 773 and 973 K consisted of external CuO and subsurface Cu2O layers. The total thickness of these scales varied from about 10 m at 773 K to about 450 m at 973 K. In contrast, thin scales formed on Cu-17%Cr-5%Al alloys oxidized between 773 and 1173 K. The exact nature of these scales could not be determined by x-ray diffraction but energy dispersive spectroscopy analyses were used to construct a scale composition map. Phenomenological oxidation mechanisms are proposed for the two alloys.
14. Functional, structural and phylogenetic analysis of domains underlying the Al-sensitivity of the aluminium-activated malate/anion transporter, TaALMT1
Technology Transfer Automated Retrieval System (TEKTRAN)
TaALMT1 (Triticum aestivum Aluminum Activated Malate Transporter) is the founding member of a novel gene family of anion transporters (ALMTs) that mediate the efflux of organic acids. A small subgroup of root-localized ALMTs, including TaALMT1, is physiologically associated with in planta aluminum (...
15. Transport properties of mixed CuAl(S1-xSex)2 as promising thermoelectric crystalline materials
Reshak, A. H.
2015-03-01
The semi-classical Boltzmann theory as implemented in the BoltzTraP code is used to study the influence of substituting S by Se in the mixed CuAl(S1-xSex)2 crystalline materials on the transport properties. The carrier concentration (n), electrical conductivity (σ / τ), Seebeck coefficient (S), electronic thermal conductivity (κe / τ), the electronic power factor (S2 σ / τ), and the figure of merit (ZT) as a function of temperature at certain value of chemical potential are calculated. The carrier concentration, electrical conductivity, electronic thermal conductivity and the electronic power factor increase exponentially with increasing temperature. CuAl(S0.75Se0.25)2 exhibits the highest n, σ / τ, κe / τ and S2 σ / τ among these compounds along the whole temperature scale. We should emphasize that S is positive for all compounds which represents p-type concentration. At room temperature CuAl(S0.25Se0.75)2 and CuAl(S0.5Se0.5)2 exhibit ZT very close to unity, which implies that these materials could be good candidates for thermoelectric applications. The state-of-the-art full potential linear augmented plane wave (FPLAPW) method is used to calculate the electronic band structure, density of states and energy gaps for CuAl(S1-xSex)2. The electron effective mass ratio (me*/me) and effective mass of the heavy holes (mhh*/me) and light holes (mlh* /me) around Γ point, the center of the BZ, for CuAlS2 and CuAlSe2 are calculated.
16. Microwave assisted sintering of Al-Cu-Mg-Si-Sn alloy.
PubMed
2012-01-01
Microwave sintering has been a well-established technique to consolidate metal powders due to its instantaneous volumetric and rapid heating as compared to conventional heating. Al-3.8Cu-1Mg-0.8Si-0.3Sn (2712) alloy powders were compacted (200 and 400 MPa) and microwave sintered at different temperatures (570 to 630 degrees C) under different atmospheres (vacuum, N2, Ar and H2). Increasing sintering temperature enhanced sintered density from 91% to 98%. Sintering under vacuum at 590 degrees C was more efficient with a densification parameter of 0.36 followed by N2, Ar and H2. Regardless of the sintering condition, phase analysis via XRD revealed the presence of only alpha-Al peak attributed to lesser time available for diffusion of alloying elements. In addition, microstructural inhomogeneity leading to more intergranular melt formation was observed for all sintered compacts. Contrasting to densification, sintering in N2 resulted in better corrosion resistance.
17. The adsorption of water on Cu2O and Al2O3 thin films
SciTech Connect
Deng, Xingyi; Herranz, Tirma; Weis, Christoph; Bluhm, Hendrik; Salmeron, Miquel
2008-06-27
The initial stages of water condensation, approximately 6 molecular layers, on two oxide surfaces, Cu{sub 2}O and Al{sub 2}O{sub 3}, have been investigated by using ambient pressure X-ray photoelectron spectroscopy at relative humidity values (RH) from 0 to >90%. Water adsorbs first dissociatively on oxygen vacancies producing adsorbed hydroxyl groups in a stoichiometric reaction: O{sub lattic} + vacancies + H{sub 2}O = 2OH. The reaction is completed at {approx}1% RH and is followed by adsorption of molecular water. The thickness of the water film grows with increasing RH. The first monolayer is completed at {approx}15% RH on both oxides and is followed by a second layer at 35-40% RH. At 90% RH, about 6 layers of H{sub 2}O film have been formed on Al{sub 2}O{sub 3}.
18. A Thermally Stable NiZn/Ta/Ni Scheme to Replace AuBe/Au Contacts in High-Efficiency AlGaInP-Based Light-Emitting Diodes
Kim, Dae-Hyun; Park, Jae-Seong; Kang, Daesung; Seong, Tae-Yeon
2017-03-01
We developed NiZn/(Ta/)Ni ohmic contacts to replace expensive AuBe/Au contacts commonly used in high-efficiency AlGaInP-based light-emitting diodes (LEDs), and compared the electrical properties of the two contact types. Unlike the AuBe/Au (130 nm/100 nm) contact, the NiZn/Ta/Ni (130 nm/20 nm/100 nm) contact shows improved electrical properties after being annealed at 500°C, with a contact resistivity of 5.2 × 10-6 Ω cm2. LEDs with the NiZn/Ta/Ni contact exhibited a 4.4% higher output power (at 250 mW) than LEDs with the AuBe/Au contact. In contrast to the trend for the AuBe/Au contact, the Ga 2p core level for the NiZn/Ta/Ni contact shifted toward lower binding energies after being annealed at 500°C. Auger electron spectroscopy (AES) depth profiles showed that annealing the AuBe/Au samples caused the outdiffusion of both Be and P atoms into the metal contact, whereas in the NiZn/Ta/Ni samples, Zn atoms indiffused into the GaP layer. The annealing-induced electrical degradation and ohmic contact formation mechanisms are described and discussed on the basis of the results of x-ray photoemission spectroscopy and AES.
19. Structural characterization of niobium oxide thin films grown on SrTiO3 (111) and (La,Sr)(Al,Ta)O3 (111) substrates
Dhamdhere, Ajit R.; Hadamek, Tobias; Posadas, Agham B.; Demkov, Alexander A.; Smith, David J.
2016-12-01
Niobium oxide thin films have been grown by molecular beam epitaxy on SrTiO3 (STO) (111) and (La0.18Sr0.82)(Al0.59Ta0.41)O3 (LSAT) (111) substrates. Transmission electron microscopy (TEM) confirmed the formation of high quality films with coherent interfaces. Films grown with higher oxygen pressure on STO (111) resulted in a (110)-oriented NbO2 phase with a distorted rutile structure, which can be described as body-centered tetragonal. The a lattice parameter of NbO2 was determined to be ˜13.8 Å in good agreement with neutron diffraction results published in the literature. Films grown on LSAT (111) at lower oxygen pressure produced the NbO phase with a defective rock salt cubic structure. The NbO lattice parameter was determined to be a ≈ 4.26 Å. The film phase/structure identification from TEM was in good agreement with in situ x-ray photoelectron spectroscopy measurements that confirmed the dioxide and monoxide phases, respectively. The atomic structure of the NbO2/STO and NbO/LSAT interfaces was determined based on comparisons between high-resolution electron micrographs and image simulations.
20. Surface Modification and In Vitro Characterization of Cp-Ti and Ti-5Al-2Nb-1Ta Alloy in Simulated Body Fluid
Sasikumar, Y.; Rajendran, N.
2012-10-01
Ti and its alloys are widely used in manufacturing orthopedic implants as prostheses for joint replacement because of their high corrosion resistance and excellent biocompatibility. However, they lack in bone-bonding ability and leads to higher rate of osteolysis and subsequent loosening of implants. In order to enhance the bone-bonding ability of these alloys, various surface-modification techniques are generally employed. The present investigation is mainly concerned with the surface modification of Cp-Ti and Ti-5Al-2Nb-1Ta alloy using a mixture of alkali and hydrogen peroxide followed by subsequent heat treatment to produce a porous gel layer with anatase structure, which enhances osseointegration. The morphological behavior was examined by x-ray diffractometer (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDX). The in vitro characterization of all the specimens was evaluated by immersing the specimens in simulated body fluid solution to assess the apatite formation over the metal surface. The apatite formation was confirmed by XRD, SEM-EDX, and Fourier transform infrared spectroscopy (FT-IR). Further, the electrochemical corrosion behaviors of both the untreated and treated specimens were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy. The results revealed that the surface-modified and heat-treated specimens exhibited higher corrosion resistance and excellent biocompatibility when compared to the chemical and untreated specimens.
1. Structural evolution of Ag-Cu nano-alloys confined between AlN nano-layers upon fast heating.
PubMed
Janczak-Rusch, J; Chiodi, M; Cancellieri, C; Moszner, F; Hauert, R; Pigozzi, G; Jeurgens, L P H
2015-11-14
The structural evolution of a Ag-Cu/AlN nano-multilayer (NML), as prepared by magnetron-sputtering on a α-Al2O3 substrate, was monitored during fast heating by real-time in situ XRD analysis (at the synchrotron), as well as by ex situ microstructural analysis using SEM, XPS and in-house XRD. The as-deposited NML is constituted of alternating nano-layers (thickness ≈ 10 nm) of a chemically inert AlN barrier and a eutectic Ag-Cu(40at%) nano-alloy. The nano-alloy in the as-deposited state is composed of a fcc matrix of Ag nano-grains (≈6 nm), which are supersaturated by Cu, and some smaller embedded Cu rich nano-grains (≈4 nm). Heating up to 265 °C activates segregation of Cu out of the supersaturated Ag nano-grains phase, thus initiating phase separation. At T > 265 °C, the phase-separated Cu metal partially migrates to the top NML surface, thereby relaxing thermally-accumulated compressive stresses in the confined alloy nano-layers and facilitating grain coarsening of (still confined) phase-separated nano-crystallites. Further heating and annealing up to 420 °C results in complete phase separation, forming extended Ag and Cu domains with well-defined coherent Ag/AlN interfaces. The observed outflow of Cu well below the eutectic melting point of the bulk Ag-Cu alloy might provide new pathways for designing low-temperature nano-structured brazing materials.
2. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates
PubMed Central
2011-01-01
The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS: 88.40.jp; 73.40.Lq; 73.50.Pz. PMID:22136081
3. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates
Wang, Xianghu; Li, Rongbin; Fan, Donghua
2011-12-01
The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS: 88.40.jp; 73.40.Lq; 73.50.Pz.
4. The dominant factors affecting the memory characteristics of (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} high-k charge-trapping devices
SciTech Connect
Gong, Changjie; Lan, Xuexin; Yin, Qiaonan; Ou, Xin; Liu, Jinqiu; Sun, Chong; Wang, Laiguo; Lu, Wei; Yin, Jiang Xu, Bo; Xia, Yidong; Liu, Zhiguo; Li, Aidong
2014-09-22
The prototypical charge-trapping memory devices with the structure p-Si/Al{sub 2}O{sub 3}/(Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x}/Al{sub 2}O{sub 3}/Pt(x = 0.5, 0.3, and 0.1) were fabricated by using atomic layer deposition and RF magnetron sputtering techniques. A memory window of 7.39 V with a charge storage density of 1.97 × 10{sup 13 }cm{sup −2} at a gate voltage of ±11 V was obtained for the memory device with the composite charge trapping layer (Ta{sub 2}O{sub 5}){sub 0.5}(Al{sub 2}O{sub 3}){sub 0.5}. All memory devices show fast program/erase speed and excellent endurance and retention properties, although some differences in their memory performance exist, which was ascribed to the relative individual band alignments of the composite (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} with Si.
5. Structure and Composition Analysis of Cu(In,Al)Se2 Thin Films Prepared by Rapid Thermal Selenization
Lee, Shi-Wei; Tseng, Bae-Heng
2012-10-01
Thin films of CuIn1-xAlxSe2 (CIAS) were prepared by stacked elemental precursor layers in an inert ambient. The stacking sequence of precursor layers may affect the kinetics of phase formation. The soda lime glass (SLG)/Cu/Al/In/Se sample heated at 750 °C for 30 s with a temperature ramp rate of 15 °C/s may react to form single-phase CIAS thin films with a chemical composition fairly close to the predetermined value. Transmission electron microscopy (TEM) analysis of a selenized film prepared at 600 °C revealed the segregation of the content of Al to the substrate side and a relatively large variation of Al distributed in a lateral direction as compared with those of other elements. Changing the Cu and Al layer sequence may affect the reaction paths and lead to the formation of a mixture of two CIAS quaternary phases with different compositions.
6. A model of the interfacial processes inhibiting the environmental degradation of Al-Cu alloys
Kearns, Jeffery Robert
A better understanding of the composition and structure of chemically treated Al alloy surfaces is necessary to devise new, more environmentally benign, coating systems for aircraft. In this work, the surface of AA2024-T3, as well as analogs for constituent intermetallic compounds (IMC), were examined at various stages of the Al alloy pretreatment and chromate conversion coating (CCC) process. A complement of techniques were used: imaging and dyanmic Secondary Ion Mass Spectroscopy (SIMS), Variable-Angle X-ray Photoelectron Spectroscopy (VA/XPS), Synchrotron Infrared Microspectroscopy (SIRS), X-ray Absorption Spectroscopy (XAS), and Electrochemical Impedance Spectroscopy (EIS). The water and hydrocarbons in commercial CCC destabilized Cr(VI) during exposure to soft x-rays. However, it was possible to prevent photochemical reduction with the ultra-clean vacuum pumping practice recently developed at Stony Brook. The type of pretreatment used prior to chromate conversion coating influenced the extent of IMC removal, Cu (re)distribution, and surface activity. Cu(I) was observed on all the chemically treated surfaces. Samples pretreated in Sanchem 1000 while galvanically coupled to a Pt mesh had a more desirable distribution of Cu for subsequent processing. Chromate reduction was not a significant factor in CCC aging over a 24-hr period, but surface dehydration and structural change were correlated and causative. Imaging SIMS revealed heterogeneities in the CCC that varied laterally with IMC in the alloy substrate. These regions were depleted in compounds containing Cr, F, and CN. Cu was found at localized sites in the CCC contact surface. Cyano groups were bound as Cr(IlI)-CNFe(H). The chromate available for CCC repair was located on matrix regions through the entire bulk of the CCC. The presence of residual contaminants (e.g. cleaning agents, metal working fluid, ink) affected the distribution of activator compounds (e.g. ferricyanide) in a CCC. The cyanide complex
7. Properties of complexes of galactomannan of Leucaena leucocephala and Al3+, Cu2+ and Pb2+.
PubMed
Lombardi, Simone Cristina; Mercê, Ana Lucia Ramalho
2003-08-01
The use of biopolymers in many industrial processes is on the increase. The different interactions of biopolymers and electrolytes either in aqueous solutions or in solid state provide different physico-chemical properties and a simple correlation cannot be established. In this study, in order to determine the properties of the complexes of galactomannan of Leucaena leucocephala (gal) with the metal ions Al3+ and Pb2+, toxic elements and Cu2+, essential, the logs of the binding constants of the complexes formed in the aqueous solutions were calculated. Their rheological properties, their thermal behavior, the infrared characteristics and shape and form of the films formed by those complexes in solid state were also determined. The aqueous solutions properties have shown a better complexation between gal and Al3+. The species distribution diagrams have shown an existence of complex species going from acidic to basic pH values. Infrared spectra have proved the complexations as well as the viscosity studies. Thermal stabilities in general were smaller in the complexed species than in the native biopolymers and the films obtained from aqueous solutions showed for Cu2+ the most different morphology compared to the biopolymer itself. A use can be suggested of this biopolymer in environmental remediations besides its already established industrial uses.
8. Precipitation Effects on the Martensitic Transformation in a Cu-Al-Ni Shape Memory Alloy
Suru, Marius-Gabriel; Lohan, Nicoleta-Monica; Pricop, Bogdan; Mihalache, Elena; Mocanu, Mihai; Bujoreanu, Leandru-Gheorghe
2016-04-01
This paper describes the effects of precipitation of α-phase on a Cu-Al-Ni shape memory alloy (SMA) with chemical composition bordering on β region. By differential scanning calorimetry, a series of reproducible heat flow fluctuations was determined on heating a hot-rolled martensitic Cu-Al-Ni SMA, which was associated with the precipitation of α-phase. Two heat treatments were given to the SMA so as to "freeze" its states before and after the thermal range for precipitation, respectively. The corresponding microstructures of the two heat-treated states were observed by optical and scanning electron microscopy and were compared with the initial martensitic state. Energy dispersive spectroscopy experiments were carried out to determine the chemical compositions of the different phases formed in heat-treated specimens. The initial as well as the heat-treated specimens with a lamellar shape were further comparatively investigated by dynamic mechanical analysis and two-way shape memory effect (TWSME) tests comprising heating-cooling cycles under a bending load. Temperature scans were applied to the three types of specimens (initial and heat-treated states), so as to bring out the effects of heat treatment. The storage modulus increased, corresponding to the reversion of thermoelastic martensite and disappeared with the formation of precipitates. These features are finally discussed in association with TWSME under bending.
9. Visible light induced H2PO(4)(-) removal over CuAlO2 catalyst.
PubMed
Benreguia, N; Omeiri, S; Bellal, B; Trari, M
2011-09-15
The delafossite CuAlO(2) is successfully used for the visible light driven H(2)PO(4)(-) reduction. It is prepared from the nitrates decomposition in order to increase the ratio of reaction surface per given mass. CuAlO(2) is a narrow band gap semiconductor which exhibits a good chemical stability with a corrosion rate of 1.70 μmol year(-1) at neutral pH. The flat band potential (+0.25 V(SCE)) is determined from the Mott-Schottky characteristic. Hence, the conduction band, positioned at (-1.19 V(SCE)), lies below the H(2)PO(4)(-) level yielding a spontaneous reduction under visible illumination. The photocatalytic process is investigated under mild conditions and 30% conversion occurs in less than ~6h with a quantum efficiency of 0.04% under full light. The concentration decreases by a factor of 39% after a second cycle. The photoactivity follows a first order kinetic with a rate constant of 6.6 × 10(-2)h(-1). The possibility of identifying the reaction products via the intensity-potential characteristics is explored. The decrease of the conversion rate over illumination time is due to the competitive water reduction.
10. Cold Spraying of Cu-Al-Bronze for Cavitation Protection in Marine Environments
Krebs, S.; Gärtner, F.; Klassen, T.
2015-01-01
Traveling at high speeds, ships have to face the problem of rudder cavitation-erosion. At present, the problem is countered by fluid dynamically optimized rudders, synthetic, and weld-cladded coatings on steel basis. Nevertheless, docking and repair is required after certain intervals. Bulk Cu-Al-bronzes are in use at ships propellers to withstand corrosion and cavitation. Deposited as coatings with bulk-like properties, such bronzes could also enhance rudder life times. The present study investigates the coating formation by cold spraying CuAl10Fe5Ni5 bronze powders. By calculations of the impact conditions, the range of optimum spray parameters was preselected in terms of the coating quality parameter η on steel substrates with different temperatures. As-atomized and annealed powders were compared to optimize cavitation resistance of the coatings. Results provide insights about the interplay between the mechanical properties of powder and substrate for coating formation. Single particle impact morphologies visualize the deformation behavior. Coating performance was assessed by analyzing microstructures, bond strength, and cavitation resistance. These first results demonstrate that cold-sprayed bronze coatings have a high potential for ensuring a good performances in rudder protection. With further optimization, such coatings could evolve towards a competitive alternative to existing anti-cavitation procedures.
11. Fabrication of Al-Cu alloy with elongated pores by continuous casting technique
Suzuki, S.; Kim, T.-B.; Nakajima, H.
2009-05-01
A1-4.5wt%Cu was unidirectionally solidified by continuous casting technique under hydrogen pressure of 0.1MPa at the transference velocities ranging from 1 to 50 mmmidmin-1. The fabricated slabs have microstructures of columnar α-dendrite and eutectic, which are typical for hypo-eutectic Al-Cu alloys. Elongated pores are observed in the eutectic region surrounded by several columnar α-dendrites. The shapes of the pores are affected by that of the surrounding α-dendrites. The average pores diameter is several ten μm smaller than the average dendrite arm spacing, which decreases with increasing solidification rate. Therefore, the pore diameter varies from about 200 μm to 30 μm with increasing transference velocity from 1 to 50 mmmidmin-1. The porosity of the fabricated samples is in the range between 2 ~ 6 %. There is not significant dependence of the porosity on the transference velocity in the range of the present study. The porosity is similar to the reported value of Al-Si, where the area fraction of eutectic region is smaller than that of α-dendrite.
12. Trace element effects on precipitation processes and mechanical properties in an Al-Cu-Li alloy
SciTech Connect
Gilmore, D.L.; Starke, E.A. Jr.
1997-07-01
A study has been made of how impurities (Na and K) and trace additions of indium, magnesium, and silicon affect the microstructure and related mechanical properties of an Al-Cu-Li alloy. Transmission electron microscopy (TEM) was used to determine the size and distribution of particles in four alloys. Indium and magnesium are both seen to stimulate T{sub 1} precipitation. Indium also modifies {theta}{double_prime} morphology, and magnesium greatly increases the number density of {theta}{double_prime} precipitates. Strain localization was observed in underaged Al-Cu-Li-In tensile samples, consistent with observed changes in precipitate structure. No superposition of the effects of indium and magnesium was seen. High-resolution analytical microscopy was used to inspect precipitates for segregation of trace elements during early stages of aging, but no segregation was found within the detection limits of the system. Variations in heat treatment were made in order to study nucleation kinetics and trace element interactions with vacancies. Indium, with a binding energy less than that of lithium, was not seen to interact with quenched-in vacancies, while magnesium, with a binding energy greater than that of lithium, had a strong interaction. Yield anisotropies and fracture toughnesses were measured. Removal of trace impurities of sodium and potassium correlated with improved fracture properties. Magnesium was observed to increase anisotropy, especially in the T8 temper. A model was used to explain the anisotropy data in terms of texture and precipitate distribution.
13. The stress-corrosion behavior of Al-Li-Cu alloys: A comparison of test methods
NASA Technical Reports Server (NTRS)
Rizzo, P. P.; Galvin, R. P.; Nelson, H. G.
1982-01-01
Two powder metallurgy processed (Al-Li-Cu) alloys with and without Mg addition were studied in aqueous 3.5% NaCl solution during the alternate immersion testing of tuning fork specimens, slow crack growth tests using fracture mechanics specimens, and the slow strain rate testing of straining electrode specimens. Scanning electron microscopy and optical metallography were used to demonstrate the character of the interaction between the Al-Li-Cu alloys and the selected environment. Both alloys are susceptible to SC in an aqueous 3.5% NaCl solution under the right electrochemical and microstructural conditions. Each test method yields important information on the character of the SC behavior. Under all conditions investigated, second phase particles strung out in rows along the extrusion direction in the alloys were rapidly attacked, and played principal role in the SC process. With time, larger pits developed from these rows of smaller pits and under certain electrochemical conditions surface cracks initiated from the larger pits and contributed directly to the fracture process. Evidence to support slow crack growth was observed in both the slow strain rate tests and the sustained immersion tests of precracked fracture mechanics specimens. The possible role of H2 in the stress corrosion cracking process is suggested.
14. Comparison of laser ablation and sputter desorption of clusters from Au7Cu5Al4
King, B. V.; Moore, J. F.; Cui, Y.; Veryovkin, I. V.; Tripa, C. E.
2014-12-01
Ionized and neutral clusters were desorbed from spangold, a polycrystalline ternary alloy with composition Au7Cu5Al4, using both a femtosecond laser beam and an energetic ion beam and the resulting time of flight mass spectra compared. Neutral clusters containing up to 7 atoms were ejected by the 15 keV Ar+ beam whereas only smaller positively and negatively charged clusters were observed from the laser ablated spangold surface. Laser ionization mass spectrometry (LIMS) positive ion spectra were dominated by Al containing cluster ions whereas Au containing ions dominated the negative LIMS spectrum. An odd-even variation in LIMS cluster yield was observed, consistent with previous results and due to fragmentation of photoionized clusters. The laser sputtered neutral mass spectrometry (laser SNMS) spectrum showed that larger desorbed clusters were gold rich. The cluster signals also followed a power law dependence with cluster size with the exponent value of 6-7.6 for sputtered mixed clusters being greater than that found from sputtering of pure elements, similar to the result found previously in the Cu-Au system.
15. Application of Cu-Al-Mn superelastic alloy bars as reinforcement elements in concrete beams
Shrestha, Kshitij C.; Araki, Yoshikazu; Nagae, Takuya; Yano, Hayato; Koetaka, Yuji; Omori, Toshihiro; Sutou, Yuji; Kainuma, Ryosuke; Ishida, Kiyohito
2012-04-01
Experimental works are done to assess the seismic behavior of concrete beams reinforced with superelastic alloy (SEA) bars. Applicability of newly developed Cu-Al-Mn SEA bars, characterized by large recovery strain, low material cost, and high machinability, have been proposed as partial replacements for conventional steel bars in order to reduce residual deformations in structures during and after intense earthquakes. Four-point reverse-cyclic bending tests were done on 1/3 scale concrete beams comprising three different types of specimens - conventional steel reinforced concrete (ST-RC), SEA reinforced concrete (SEA-RC), and SEA reinforced concrete with pre-tensioning (SEA-PC). The results showed that SEA reinforced concrete beams demonstrated significant enhancement in crack recovery capacity in comparison to steel reinforced beam. Average recovery of cracks for each of the specimens was 21% for ST-RC, 84% for SEA-RC, and 86% for SEA-PC. In addition, SEA-RC and SEA-PC beams demonstrated strong capability of recentering with comparable normalized strength and ductility relative to conventional ST-RC beam specimen. ST-RC beam, on the other hand, showed large residual cracks due to progressive reduction in its re-centering capability with each cycle. Both the SEA-RC and SEA-PC specimens demonstrated superiority of Cu-Al-Mn SEA bars to conventional steel reinforcing bars as reinforcement elements.
16. Tensile Properties of Al-Cu 206 Cast Alloys with Various Iron Contents
Liu, K.; Cao, X.; Chen, X.-G.
2014-05-01
The Al-Cu 206 cast alloys with varying alloy compositions ( i.e., different levels of Fe, Mn, and Si) were investigated to evaluate the effect of the iron-rich intermetallics on the tensile properties. It is found that the tensile strength decreases with increasing iron content, but its overall loss is less than 10 pct over the range of 0.15 to 0.5 pct Fe at 0.3 pct Mn and 0.3 pct Si. At similar iron contents, the tensile properties of the alloys with dominant Chinese script iron-rich intermetallics are generally higher than those with the dominant platelet phase. In the solution and artificial overaging condition (T7), the tensile strength of the 206 cast alloys with more than 0.15 pct Fe is satisfactory, but the elongation does not sufficiently meet the minimum requirement of ductility (>7 pct) for critical automotive applications. However, it was found that both the required ductility and tensile strength can be reached at high Fe levels of 0.3 to 0.5 pct for the alloys with well-controlled alloy chemistry and microstructure in the solution and natural aging condition (T4), reinforcing the motivation for developing recyclable high-iron Al-Cu 206 cast alloys.
17. Growth of nanostructured Cu-Al-O film deposited on porous aluminium oxide
Park, Y.; Ko, H.; Shim, I.-B.; Kim, C. S.; Kouh, T.
2010-03-01
Anodic aluminium oxide has been gaining much attention due to the formation of a highly ordered porous structure, and this self-ordered structure is very appealing as an alternate method for fabricating various nanostructures and devices. On top of this porous aluminium oxide substrate prepared by two-step anodization technique, we have RF-sputtered Cu-Al-O thin films from a single-phase CuAlO 2 target at room temperature. These films show the formation of a highly ordered array of clusters on the nucleation sites provided by the porous substrate with their sizes increasing with film thickness, following the hexagonal pattern underneath. The corresponding surface coverage of the film on the substrate is proportional to the square of film thickness, which can be understood with a simple two-dimensional disk model. Our study suggests that the underlying structure of the anodic aluminium oxide substrate plays a crucial role on the growth of nanostructured thin films and affects the detailed growth mechanism.
18. Al and Si Alloying Effect on Solder Joint Reliability in Sn-0.5Cu for Automotive Electronics
Hong, Won Sik; Oh, Chulmin; Kim, Mi-Song; Lee, Young Woo; Kim, Hui Joong; Hong, Sung Jae; Moon, Jeong Tak
2016-12-01
To suppress the bonding strength degradation of solder joints in automotive electronics, we proposed a mid-temperature quaternary Pb-free Sn-0.5Cu solder alloy with minor Pd, Al, Si and Ge alloying elements. We manufactured powders and solder pastes of Sn-0.5Cu-(0.01,0.03)Al-0.005Si-(0.006-0.007)Ge alloys ( T m = 230°C), and vehicle electronic control units used for a flame-retardant-4 printed circuit board with an organic solderability preservative finish were assembled by a reflow soldering process. To investigate the degradation properties of solder joints used in engine compartments, thermal cycling tests were conducted from -40°C to 125°C (10 min dwell) for 1500 cycles. We also measured the shear strength of the solder joints in various components and observed the microstructural evolution of the solder joints. Based on these results, intermetallic compound (IMC) growth at the solder joints was suppressed by minor Pd, Al and Si additions to the Sn-0.5Cu alloy. After 1500 thermal cycles, IMC layers thicknesses for 100 parts per million (ppm) and 300 ppm Al alloy additions were 6.7 μm and 10 μm, compared to the as-reflowed bonding thicknesses of 6 μm and 7 μm, respectively. Furthermore, shear strength degradation rates for 100 ppm and 300 ppm Al(Si) alloy additions were at least 19.5%-26.2%. The cause of the improvement in thermal cycling reliability was analyzed using the (Al,Cu)-Sn, Si-Sn and Al-Sn phases dispersed around the Cu6Sn5 intermetallic at the solder matrix and bonding interfaces. From these results, we propose the possibility of a mid-temperature Sn-0.5Cu(Pd)-Al(Si)-Ge Pb-free solder for automotive engine compartment electronics.
19. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments
Holroyd, N. J. Henry; Scamans, G. M.
2013-03-01
Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack ("pop-in" vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies ( E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (<0.2 wt pct) are typically ranging from
20. Thermal and Microstructure Characterization of Zn-Al-Si Alloys and Chemical Reaction with Cu Substrate During Spreading
Berent, Katarzyna; Pstruś, Janusz; Gancarz, Tomasz
2016-08-01
The problems associated with the corrosion of aluminum connections, the low mechanical properties of Al/Cu connections, and the introduction of EU directives have forced the potential of new materials to be investigated. Alloys based on eutectic Zn-Al are proposed, because they have a higher melting temperature (381 °C), good corrosion resistance, and high mechanical strength. The Zn-Al-Si cast alloys were characterized using differential scanning calorimetry (DSC) measurements, which were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed at temperature ranges of -50 to 250 °C and 25 to 300 °C, respectively. The addition of Si to eutectic Zn-Al alloys not only limits the growth of phases at the interface of liquid solder and Cu substrate but also raises the mechanical properties of the solder. Spreading test on Cu substrate using eutectic Zn-Al alloys with 0.5, 1.0, 3.0, and 5.0 wt.% of Si was studied using the sessile drop method in the presence of QJ201 flux. Spreading tests were performed with contact times of 1, 8, 15, 30, and 60 min, and at temperatures of 475, 500, 525, and 550 °C. After cleaning the flux residue from solidified samples, the spreadability of Zn-Al-Si on Cu was determined. Selected, solidified solder/substrate couples were cross-sectioned, and the interfacial microstructures were studied using scanning electron microscopy and energy dispersive x-ray spectroscopy. The growth of the intermetallic phase layer was studied at the solder/substrate interface, and the activation energy of growth of Cu5Zn8, CuZn4, and CuZn phases were determined.
1. Influence of Li Addition to Zn-Al Alloys on Cu Substrate During Spreading Test and After Aging Treatment
Gancarz, Tomasz; Pstrus, Janusz; Cempura, Grzegorz; Berent, Katarzyna
2016-12-01
The spreading of Zn-Al eutectic-based alloys with 0.05 wt.%, 0.1 wt.%, and 0.2 wt.% Li on Cu substrate has been studied using the sessile drop method in presence of QJ201 flux. Wetting tests were performed after 1 min, 3 min, 8 min, 15 min, 30 min, and 60 min of contact at temperatures of 475°C, 500°C, 525°C, and 550°C. Samples after spreading at 500°C for 1 min were subjected to aging for 1 day, 10 days, and 30 days at temperature of 120°C, 170°C, and 250°C. The spreadability of eutectic Zn-5.3Al alloy with different Li contents on Cu substrate was determined in accordance with ISO 9455-10:2013-03. Selected solidified solder-substrate couples were, after spreading and aging tests, cross-sectioned and subjected to scanning electron microscopy, energy-dispersive spectroscopy (EDS), and x-ray diffraction (XRD) analysis of the interfacial microstructure. An experiment was designed to demonstrate the effect of Li addition on the kinetics of the formation and growth of CuZn, Cu5Zn8, and CuZn4 intermetallic compound (IMC) phases, during spreading and aging. The IMC layers formed at the interface were identified using XRD and EDS analyses. Increasing addition of Li to Zn-Al alloy caused a reduction in the thickness of the IMC layer at the interface during spreading, and an increase during aging. The activation energy was calculated, being found to increase for the Cu5Zn8 phase but decrease for the CuZn and CuZn4 phases with increasing Li content in the Zn-Al-Li alloys. The highest value of 142 kJ mol-1 was obtained for Zn-Al with 1.0 Li during spreading and 69.2 kJ mol-1 for Zn-Al with 0.05 Li during aging. Aging at 250°C caused an increase in only the Cu5Zn8 layer, which has the lowest Gibbs energy in the Cu-Zn system. This result is connected to the high diffusion of Cu from the substrate to the solder.
2. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy
PubMed Central
Zhai, W.; Wang, B. J.; Liu, H. M.; Hu, L.; Wei, B.
2016-01-01
The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures. PMID:27841283
3. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy
Zhai, W.; Wang, B. J.; Liu, H. M.; Hu, L.; Wei, B.
2016-11-01
The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.
4. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy.
PubMed
Zhai, W; Wang, B J; Liu, H M; Hu, L; Wei, B
2016-11-14
The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.
5. Characteristics of the Energetic Micro-initiator Through Integrating Al/Ni Nano-multilayers with Cu Film Bridge
Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Yan, Yichao; Zhang, Wanli; Li, Yanrong
2017-01-01
An energetic micro-initiator through integrating Al/Ni nano-multilayers with Cu film bridge was investigated in this study. The Cu film bridge was initially fabricated with wet etching, and Al/Ni nano-multilayers were alternately deposited on the surface of Cu film bridge by magnetron sputtering. The periodic layer structure of Al/Ni nano-multilayers was verified by scanning electron microscopy. The exothermic reaction in Al/Ni nano-multilayers can be initiated with onset reaction temperature as low as 503 K, and the total reaction heat is about 774.6 J/g. This energetic micro-initiator exhibited improved performances with lower threshold voltage, smaller initiation energy, and higher explosion temperature compared with Cu film bridge. An extra violent explosion phenomenon with longer duration time and larger quantities of ejected product particles was detected on this energetic micro-initiator by high-speed camera. Overall, the electric explosion performances of Cu film bridge can be improved evidently with the integration of Al/Ni nano-multilayers.
6. Wear and Friction Behavior of the Spray-Deposited SiCp/Al-20Si-3Cu Functionally Graded Material
Su, B.; Yan, H. G.; Chen, J. H.; Zeng, P. L.; Chen, G.; Chen, C. C.
2013-05-01
The spray-deposited SiCp/Al-20Si-3Cu functionally graded material (FGM) can meet the structure design requirements of brake disk. The effects of rotational speed and load on the wear and friction behaviors of the SiCp/Al-20Si-3Cu FGM sliding against the resin matrix friction material were investigated. For comparison, the wear and friction behaviors of a commercially used cast iron (HT250) brake rotor were also studied. The results indicate that the friction coefficient of the SiCp/Al-20Si-3Cu FGM decreases constantly with the increase of load or rotational speed and is affected by the gradient distribution of SiC particles. The wear rate of the SiCp/Al-20Si-3Cu FGM firstly increases, then decreases and finally increases again with increasing load or speed, and is about 1/10 of that of HT250. Based on observations and analyses on the morphology and substructure of the worn surface, the mechanical mixing layer acts as a protective coating and lubricant, and its thickness reduces with the SiC content increasing. Furthermore, it is proposed that the dominant wear mechanism of SiCp/Al-20Si-3Cu FGM changes from the abrasive wear to the oxidative wear and further to the delamination wear with increasing load or speed.
7. Hydrothermal growth and conductivity enhancement of (Al, Cu) co-doped ZnO nanorods thin films
Chakraborty, Mohua; Mahapatra, Preetilata; Thangavel, R.
2016-05-01
The incorporation of Al, Cu co-doping in ZnO host lattice plays an important role in modification of structural, optical and electrical properties in optoelectronic devices. In the present work, we were grown one dimensional ZnO nanorods (NRs) doped with different concentration of Al (0%~5%) and Cu was kept 20 M% on ITO glass substrates using a facile hydrothermal method, and investigated the effect of the codoping on the surface morphology and the electrical and optical performances of the doped ZnO NRs as photo anodes for solar water splitting applications. The crystallite size of NRs shows tuning in the band gap between 3.194 (Zn0.79Al0.01Cu0.2O) to 3.212 eV (Zn0.75Al0.05Cu0.2O) with Aluminium doping concentration and a remarkable improvement in current density (J) from 0.05 mA/cm2 to 4.98 mA/cm2 was achieved by incorporating Al and Cu has a critical effect of ZnO nanorods.
8. Growth morphology of single-crystal grains obtained by directional crystallisation of an Al-Cu-Fe alloy
Surowiec, Marian; Bogdanowicz, Wlodzimierz; Krawczyk, Jacek; Formanek, Bolesław; Sozanska, Maria
2011-07-01
Quasicrystalline as well as crystalline faceted single grains of four phases were obtained during directional crystallisation of an Al-Cu-Fe alloy by the Bridgman technique. The monoclinic λ phase, Al13(Cu, Fe)4, dominating at high temperatures formed single-crystal lamellae 0.5 mm to 1 mm thick. A second type of attractive morphological form exhibiting flux dissolution terraces was observed on spherical single crystals of β phase Al(Fe, Cu). Rectangular, hexagonal and octagonal shaped dissolution terraces were revealed at the positions of two-, three- and four-fold symmetry axes, respectively. A single quasicrystalline ψ phase, Al6Cu2Fe, exhibited icosahedral symmetry with growth forms of a dodecahedron with pentagonal facets. The flux dissolution of the β phase apparently plays an essential role in a peritectic reaction leading to quasicrystalline ψ phase formation. Polygonal single grains of ω phase Al7Cu2Fe exhibiting tetragonal symmetry formed the fourth type of thermodynamically stable growth forms. Single grains of the ω phase crystallised in the form of pellets with an octagonal cross-section. The growth morphology of the stable phases was investigated by scanning electron microscopy. The chemical composition of the growth forms described was confirmed by X-ray microanalysis using a scanning electron microscope, whereas the phase composition was determined using electron selected area diffraction and X-ray powder diffraction.
9. Characteristics of the Energetic Micro-initiator Through Integrating Al/Ni Nano-multilayers with Cu Film Bridge.
PubMed
Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Yan, Yichao; Zhang, Wanli; Li, Yanrong
2017-12-01
An energetic micro-initiator through integrating Al/Ni nano-multilayers with Cu film bridge was investigated in this study. The Cu film bridge was initially fabricated with wet etching, and Al/Ni nano-multilayers were alternately deposited on the surface of Cu film bridge by magnetron sputtering. The periodic layer structure of Al/Ni nano-multilayers was verified by scanning electron microscopy. The exothermic reaction in Al/Ni nano-multilayers can be initiated with onset reaction temperature as low as 503 K, and the total reaction heat is about 774.6 J/g. This energetic micro-initiator exhibited improved performances with lower threshold voltage, smaller initiation energy, and higher explosion temperature compared with Cu film bridge. An extra violent explosion phenomenon with longer duration time and larger quantities of ejected product particles was detected on this energetic micro-initiator by high-speed camera. Overall, the electric explosion performances of Cu film bridge can be improved evidently with the integration of Al/Ni nano-multilayers.
10. Microstructure Investigation of Cu-Ni Base Al2O3 Nanocomposites: From Nanoparticles Synthesis to Consolidation
Ramos, M. I.; Suguihiro, N. M.; Brocchi, E. A.; Navarro, R.; Solorzano, I. G.
2017-02-01
Different compositions of Cu-Ni/Al2O3 nanocomposites were prepared by a chemical-based synthesis of co-formed oxides (CuO-NiO-Al2O3) nanoparticles followed by selective hydrogen reduction of the Cu and Ni oxides and finally by consolidation into pellets. The synthesized composites with both phases (metallic and oxide) containing nanoparticles in the 5 to 60 nm range have been systematically produced. Micro- and nanoscale characterization techniques were extensively employed in all stages of the process. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses have shown a heterogeneous distribution of chemical elements resulting in the formation of Cu- and Ni-rich nanoparticles containing Al2O3 phase in a controlled low volume fraction, which later mostly dispersed between the metallic particle and, to a lesser extent, within metallic particles. After consolidation, under uniaxial pressure followed by sintering, the compacted nanocomposite observed in the transmission electron microscope (TEM) revealed that the Al2O3 have been more homogeneously distributed as such: the majority of it at the newly formed grain boundaries of the consolidated pellet and a small part of it within the metallic Cu-Ni matrix. Microhardness measurements demonstrate that dispersion of Al2O3 was successfully achieved as reinforcement phase, yielding up to 100 pct increase in hardness.
11. Icosahedral AlCuFe quasicrystal at high pressure and temperature and its implications for the stability of icosahedrite
PubMed Central
Stagno, Vincenzo; Bindi, Luca; Shibazaki, Yuki; Tange, Yoshinori; Higo, Yuji; Mao, H.-K.; Steinhardt, Paul J.; Fei, Yingwei
2014-01-01
The first natural-occurring quasicrystal, icosahedrite, was recently discovered in the Khatyrka meteorite, a new CV3 carbonaceous chondrite. Its finding raised fundamental questions regarding the effects of pressure and temperature on the kinetic and thermodynamic stability of the quasicrystal structure relative to possible isochemical crystalline or amorphous phases. Although several studies showed the stability at ambient temperature of synthetic icosahedral AlCuFe up to ~35 GPa, the simultaneous effect of temperature and pressure relevant for the formation of icosahedrite has been never investigated so far. Here we present in situ synchrotron X-ray diffraction experiments on synthetic icosahedral AlCuFe using multianvil device to explore possible temperature-induced phase transformations at pressures of 5 GPa and temperature up to 1773 K. Results show the structural stability of i-AlCuFe phase with a negligible effect of pressure on the volumetric thermal expansion properties. In addition, the structural analysis of the recovered sample excludes the transformation of AlCuFe quasicrystalline phase to possible approximant phases, which is in contrast with previous predictions at ambient pressure. Results from this study extend our knowledge on the stability of icosahedral AlCuFe at higher temperature and pressure than previously examined, and provide a new constraint on the stability of icosahedrite. PMID:25070248
12. Structure and nanomechanical characteristics of Al-Cu-Mg-Si alloy with partly liquated grain boundaries upon heat treatment
Chikova, O. A.; Reznik, P. L.; Ovsyannikov, B. V.
2016-12-01
The microstructure, phase composition, and mechanical characteristics of the structural constituents of an Al-Cu-Mg-Si alloy in which the liquation of grain boundaries occurred during heat treatment have been studied. Bands of the (Al + Al15(Fe, Mn)3Si2) eutectics have been observed at the grain boundaries. An algorithm for calculating the additional pressure, which results from mechanical impact on the metal containing these bands has been described.
13. Surface characteristics of Ti-6Al-4V alloy by EDM with Cu-SiC composite electrode
Li, L.; Feng, L.; Bai, X.; Li, Z. Y.
2016-12-01
Ti-6Al-4V alloy is widely used in many industries due to its outstanding properties. However, it has poor machinability using conventional mechanical cutting process. Electrical discharge machining is an alternative competitive process to machine titanium alloy by electrical erosion. This article studies the machining characteristics of Ti-6Al-4V with Cu-SiC composite electrode. Surface topography, subsurface microstructure, energy dispersive spectroscopy analysis, and micro-hardness have been analyzed. The machined surfaces show irregular compound structures, droplets of debris, shallow craters, and micro-pores. The surfaces processed by Cu-SiC electrode have fewer number of microcracks compared with that by Cu electrode. Continuous and uniform hardened layer can be achieved by Cu-SiC electrode. The hardened layer has significantly higher hardness than the bulk material because the new phases of TiC and TiSi2 were created on the surface.
14. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders
Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.
2016-12-01
Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu6Sn5 phase during solidification. In this study, the number and size of Cu6Sn5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu6Sn5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu6Sn5 phases. Transitions in the Cu6Sn5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 103 to 104 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu6Sn5 nucleant relationship. In addition, little evidence of the formation or decomposition of the ternary- β phase in the solidified alloys was noted. Solidification pathways omitting the formation of the ternary- β phase agreed well with observed room temperature microstructures.
15. Effect of Al2O3 on the sintering of garnet-type Li6.5La3Zr1.5Ta0.5O12
SciTech Connect
Wang, Yuxing; Yan, Pengfei; Xiao, Jie; Lu, Xiaochuan; Zhang, Ji-Guang; Sprenkle, Vincent L.
2016-10-01
It is widely recognized that Al plays a dual role in the fabrication of garnet-type solid electrolytes, i.e., as a dopant that stabilizes the cubic structure and a sintering aid that facilitates the densification. However, the sintering effect of Al2O3 has not been well understood so far because Al is typically “unintentionally” introduced into the sample from the crucible during the fabrication process. In this study, we have investigated the sintering effect of Al on the phase composition, microstructure, and ionic conductivity of Li6.5La3Zr1.5Ta0.5O12 by using an Al-free crucible and intentionally adding various amounts of γ-Al2O3. It was found that the densification of Li6.5La3Zr1.5Ta0.5O12 occurred via liquid-phase sintering, with evidence of morphology change among different compositions. Among all of the compositions, samples with 0.05 mol of Al per unit formula of garnet oxide (i.e., 0.3 wt% Al2O3) exhibited the optimal microstructure and the highest total ionic conductivity of 5 10-4 S cm-1 at room temperature.
16. Crystallographic Features and State Stability of the Decagonal Quasicrystal in the Al-Co-Cu Alloy System
Nakayama, Kei; Mizutani, Akito; Koyama, Yasumasa
2016-11-01
In the Al-Co-Cu alloy system, both the decagonal quasicrystal with the space group of Poverline{10}m2 and its approximant Al13Co4 phase with monoclinic Cm symmetry are present around 20 at. % Co-10 at. % Cu. In this study, we examined the crystallographic features of prepared Al-(30 - x) at. % Co-x at. % Cu samples mainly by transmission electron microscopy in order to make clear the crystallographic relation between the decagonal quasicrystal and the monoclinic Al13Co4 structure. The results revealed a coexistence state consisting of decagonal quasicrystal and approximant Al13Co4 regions in Al-20 at. % Co-10 at. % Cu alloy samples. With the help of the coexistence state, the orientation relationship was established between the monoclinic Al13Co4 structure and the decagonal quasicrystal. In the determined relationship, the crystallographic axis in the quasicrystal was found to be parallel to the normal direction of the (010)m plane in the Al13Co4 structure, where the subscript m denotes the monoclinic system. Based on data obtained experimentally, the state stability of the decagonal quasicrystal was also examined in terms of the Hume-Rothery (HR) mechanism on the basis of the nearly-free-electron approximation. It was found that a model based on the HR mechanism could explain the crystallographic features such as electron diffraction patterns and atomic arrangements found in the decagonal quasicrystal. In other words, the HR mechanism is most likely appropriate for the stability of the decagonal quasicrystal in the Al-Co-Cu alloy system.
17. Nanohardness, corrosion and protein adsorption properties of CuAlO2 films deposited on 316L stainless steel for biomedical applications
Chang, Shih-Hang; Chen, Jian-Zhang; Hsiao, Sou-Hui; Lin, Guan-Wei
2014-01-01
This study preliminarily assesses the biomedical applications of CuAlO2 coatings according to nanoindentation, electrochemical, and protein adsorption tests. Nanoindentation results revealed that the surface hardness of 316L stainless steel increased markedly after coating with CuAlO2 films. Electrochemical tests of corrosion potential, breakdown potential, and corrosion current density showed that the corrosion resistance properties of 316L stainless steel are considerably improved by CuAlO2 coatings. Bicinchoninic acid (BCA) protein assay results revealed that the protein adsorption behavior of 316L stainless steel did not exhibit notable differences with or without CuAlO2 coatings. A CuAlO2 coating of 100 nm thickness improved the surface nanohardness and corrosion resistance ability of 316L stainless steel. CuAlO2 is a potential candidate for biomaterial coating applications, particularly for surface modification of fine, delicate implants.
18. Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.
PubMed
Guo, Sai; Lu, Yanjin; Wu, Songquan; Liu, Lingling; He, Mengjiao; Zhao, Chaoqian; Gan, Yiliang; Lin, Junjie; Luo, Jiasi; Xu, Xiongcheng; Lin, Jinxin
2017-03-01
In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti2Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder.
19. The mechanism of electromigration failure of narrow Al-2Cu-1Si thin-film interconnects
SciTech Connect
Kim, C.; Morris, J.W. Jr. )
1993-05-15
This work is principally concerned with the microstructure of electromigration failure in narrow Al-2Cu-1Si conducting lines on Si. Samples were patterned from 0.5-[mu]m-thick vapor-deposited films with mean grain size of 2.4 [mu]m, and had linewidths of 1.3 [mu]m ([ital W]/[ital G][approx]0.5), 2 [mu]m ([ital W]/[ital G][approx]0.8), and 6 [mu]m ([ital W]/[ital G][approx]2.5). The lines were tested to failure at [ital T]=226 [degree]C and [ital j]=2.5[times]10[sup 6] A/cm[sup 2]. Other samples were tested over a range of substrate temperatures and current densities to test the effect of these variables, and 1.3 [mu]m lines were tested after preaging at 226 [degree]C for various times to change the Cu-precipitate distribution prior to testing. Three failure modes were observed: The 6 [mu]m specimens failed by separation along grain boundaries with an apparent activation energy of 0.65 eV; the 1.3 [mu]m specimens that were preaged for 24 h failed after very long times by gradual thinning to rupture; all other narrow lines failed by the transgranular-slit mechanism with an activation energy near 0.93 eV. Microstructural studies suggest that the transgranular-slit failure mechanism is due to the accumulation of a supersaturation of vacancies in the bamboo grains that terminate polygranular segments in the line. Failure occurs after Cu has been swept from the grain that fails. Failure happens first at the end of the longest polygranular segment of the line, at a time that decreases exponentially with the polygranular segment length. Preaging the line to create a more stable distribution of Cu lengthens the time required to sweep Cu from the longest polygranular segment, and significantly increases the time to failure. In the optimal case the transgranular-slit failure mechanism is suppressed, and the bamboo grain fails by diffuse thinning to rupture.
20. Structural changes in a Cu/Al sub 2 O sub 3 catalyst when used for oxidation of carbon monoxide
SciTech Connect
Laine, J.; Severino, F. ); Lopez-Agudo, A.; Fierro, J.L.G. )
1991-05-01
It has been found when copper is deposited on high surface area alumina using loadings below about 4 wt% Cu and calcined below 773 K that a surface spinel CuAl{sub 2}O{sub 4} forms, in which most of the Cu{sup 2+} is located in a distorted octahedral geometry. Previous results have indicated that, for such loadings, the most active catalysts for CO oxidation at 473 K are obtained by prereduction with pure CO; however, the initial active state was found to be affected by a significant deactivation. The present study was undertaken to elucidate the structural changes accompanying deactivation during CO oxidation.
1. Effect of heterogeneous precipitation on age-hardening of Al{sub 2}O{sub 3} particle dispersion Al-4mass% Cu composite produced by mechanical alloying
SciTech Connect
Arakawa, S.; Hatayama, T.; Matsugi, K.; Yanagisawa, O.
2000-04-14
The acceleration of aging kinetics has been frequently observed in aluminum matrix composites produced by ingot or powder metallurgy. Recently, in the mechanically alloyed (MA) Al-4mass%Cu/Al{sub 2}O{sub 3} composites, the authors have found that the age-hardening response significantly decreases, and that considerable stable {theta} phases are formed at a very short aging time. The purposes of this study are to investigate the local precipitation behaviors, and attempt to clarify the dominant microstructural factors of the decrease in the age-harden ability and the acceleration of the age-hardening kinetics in the Al{sub 2}O{sub 3} particle dispersion Al-4mass%Cu composites produced by mechanical alloying. In order to build a basis for comparison, the age-hardening behaviors of the unreinforced matrix alloy (IM alloy), which is produced by ingot metallurgy technique, are also investigated.
2. Al2O3/SUS304 Brazing via AgCuTi-W Composite as Active Filler
Su, Cherng-Yuh; Zhuang, Xie-Zongyang; Pan, Cheng-Tang
2014-03-01
Alumina ceramic (α-Al2O3) was brazed to stainless steel (SUS304) using an Ag-Cu-Ti + W composite filler and a traditional active brazing filler alloy (CuSil-ABA). Then, the effects of the presence of W particles and of the brazing parameters on the microstructures and mechanical properties of the brazed joints were investigated. The maximum tensile strength of the joints obtained using Ag-Cu-Ti + W composite filler was 13.2 MPa, which is similar to that obtained using CuSil-ABA filler (13.5 MPa). When the joint was brazed at 930 °C for 30 min, the tensile strengths decreased for both kinds of fillers, although the strength was slightly higher for the Ag-Cu-Ti + W composite filler than for the Ag-Cu-Ti filler. The interfacial microstructure results show that the Ti reacts with W to form a Ti-W-O compound in the brazing alloy. When there are more W particles in the brazing alloy, the thickness of the Ti X O Y reaction layer near the alumina ceramic decreases. Moreover, W particles added to the brazing alloy can reduce the coefficient of thermal expansion of the brazing alloy, which results in lower residual stress between the Al2O3 and SUS304 in the brazing joints and thus yields higher tensile strengths as compared to those obtained using the CuSil-ABA brazing alloy.
3. Effect of magnesium on the aging behavior of Al-Zn-Mg-Cu/Al2O3 metal matrix composites
Chou, Ming-Chun; Chao, Chuen-Guang
1996-07-01
The effect of magnesium content on the aging behavior of Al-Zn-Mg-Cu alloy reinforced with alumina (A12O3) was studied by using the differential scanning calorimetry (DSC) technique and hardness measurement. The magnesium contents were studied in the range from 1.23 to 2.97 wt pct. The addition of magnesium was found to increase the coherent Guinier-Preston (GP) zones in com-posites. The apparent formation enthalpy of GP zones of composites (0.1 V f) was 0.932 cal/g for 1.23 wt pct magnesium content and 1.375 cal/g for 2.97 wt pct magnesium content. The precipitation time to achieve the maximum hardness in the composites depends on the magnesium content. The time changed from 12 to 48 hours as the magnesium content increased from 1.23 to 2.97 wt pct. Both Vickers microhardness and Rockwell hardness increased with increasing magnesium content. The maximum hardness occurred in the composites that contained maximum amounts of GP zones and η' precipitates. However, the microhardness of the composites was always lower than that of monolithic alloys due to the alumina fibers which caused the suppression of GP zones and η' for-mation in the composites.
4. Ab Initio Calculations and Experimental Properties of CuAl x Ga1- x Te2 for Photovoltaic Solar Cells
Benabdeslem, M.; Sehli, H.; Rahal, S.; Benslim, N.; Bechiri, L.; Djekoun, A.; Touam, T.; Boujnah, M.; El Kenz, A.; Benyoussef, A.; Portier, X.
2016-02-01
Nanostructured chalcopyrite CuAl x Ga1- x Te2 ( x = 0.25, 0.50, and 0.75) has been prepared by ball milling of Cu, Al, Ga, and Te precursors. Preliminary ab initio calculations of the main properties have been performed on the prototype chalcopyrite semiconductor CuAlGaTe2. The simulation method used is based on the density functional theory within the framework of pseudo-potentials and plane waves. Band Structure calculations suggest that CuAlGaTe2 is a direct bandgap semiconductor having a band gap = 1.35 eV. In the experimental part, x-ray diffraction analysis revealed the presence of (112), (220)/(204), (312)/(116), and (400) reflections for all the milled powders characteristic of the chalcopyrite structure. A shift in peaks towards a higher value of 2 θ is observed with the increase in Al composition. With increasing Al content, it is found that the average crystallite size decreases whereas the bandgap energy increases from 1.34 eV to 1.51 eV. Compared with experimental data, calculated results by GGA-mBJ functional quantitatively agree with experimental data.
5. A Compton scattering study on the Hume-Rothery mechanism of AlCu TM (TM: transition metal) quasicrystals
Okada, J. T.; Sakurai, Y.; Watanabe, Y.; Ishikawa, R.; Yokoyama, Y.; Hiraoka, N.; Itou, M.; Nanao, S.
2006-08-01
The electron momentum distributions in icosahedral Al64Cu23Fe13, icosahedral Al63Cu23Ru13 and decagonal Al65Cu15Co20 quasicrystals have been studied using the high-resolution Compton scattering technique. The electron-per-atom ratios (e/a) of the quasicrystals were determined quantitatively for the first time from the Compton profiles. The radii of the Fermi spheres were evaluated from the values of e/a on the basis of the free-electron model. Comparisons between the radius of the Fermi spheres and the size of the quasi-Brillouin zones show that the icosahedral quasicrystals meet the empirical matching condition, while the decagonal quasicrystal does not do this so well. This implies that the Hume-Rothery mechanism works for the formation of the pseudogap near the Fermi level in the icosahedral quasicrystals, although it operates only slightly in the decagonal quasicrystal.
6. Microstructural and mechanical properties of Al-4.5wt% Cu reinforced with alumina nanoparticles by stir casting method
Valibeygloo, N.; Azari Khosroshahi, R.; Taherzadeh Mousavian, R.
2013-10-01
The microstructure and mechanical properties of Al-4.5wt% Cu alloy reinforced with different volume fractions (1.5vol%, 3vol%, and 5vol%) of alumina nanoparticles, fabricated using stir casting method, were investigated. Calculated amounts of alumina nanoparticles (about ϕ50 nm in size) were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the Al-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the alloy, resulting in higher peak hardness values.
7. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy
SciTech Connect
G.A. Young; J.R. Scully
2001-09-12
It is well established that Al-Zn-Mg-(Cu) aluminum alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are commonly used to increase HEAC resistance at the expense of strength. Overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). When freshly bared coupons of AA 7050 are exposed to 90 C, 90% RH air, hydrogen ingress follows inverse-logarithmic-type kinetics and is equivalent for underaged (HEAC susceptible) and overaged (HEAC resistant) tempers. However, when the native oxide is allowed to form (24 hrs in 25 C, 40% RH lab air) prior to exposure to 90 C, 90% RH air, underaged alloy shows significantly greater hydrogen ingress than the overaged alloy. Humid air is a very aggressive environment producing local ({approx}1{micro}m) hydrogen concentrations in excess of 10,000 wt. ppm at 90 C. In the copper bearing alloy, overaging also effects the apparent diffusivity of hydrogen. As AA 7050 is aged from underaged {yields} peak aged {yields} overaged, the activation energy for hydrogen diffusion increases and the apparent diffusivity for hydrogen decreases, In the low copper alloy, overaging has little effect on hydrogen diffusion. Comparison of the apparent activation energies for hydrogen diffusion and for K independent (stage II) crack growth
8. Influence of MnC2O4 microadditives on combustion characteristics of CuO/Al nanoenergetics
Painuly, Madhusudan; Patel, Vinay Kumar; Bhattacharya, Shantanu
2016-05-01
In this work, we have investigated the catalytic effect of MnC2O4 microrods on combustion characteristics of CuO/nAl nanoenergetic composites. CuO nanorods were prepared by solid state synthesis method using the nonionic surfactant of poly(ethylene)glycol of molecular weight 400 (PEG400). The crystal information and microstructure of CuO/nAl nanoenergetics were studied by X-ray diffractometry and Transmission Electron microscopy. Microrods shaped manganese oxalate (MnC2O4) were fabricated by using mild thermal precipitation and aging process and confirmed by energy dispersive X-ray spectroscopy (EDS). The microstructures of MnC2O4 microrods and the nanoenergetic composites of CuO/nAl/MnC2O4 were characterized by Field emission scanning electron microscopy (FE-SEM) imaging. The addition of MnC2O4 microrods has demonstrated a significant enhancement in dynamic pressure-time characteristics of CuO/nAl nanoenergetics.
9. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction
Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed
2017-02-01
Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.
10. Hydrogen production by thermocatalytic decomposition of methane over Ni-Al and Ni-Cu-Al catalysts: Effect of calcination temperature
Echegoyen, Y.; Suelves, I.; Lázaro, M. J.; Moliner, R.; Palacios, J. M.
Thermo catalytic decomposition of methane using Ni-Al and Ni-Cu-Al catalyst prepared by fusion of the corresponding nitrates is studied. The effects of catalyst calcination temperature on the hydrogen yields and the characteristics of the carbon obtained are studied. The role of copper has been also analyzed. Whatever the calcination temperature, all the catalysts show a high and almost constant hydrogen yield without catalyst deactivation after 8 h on stream, which confirms the good performance of this kind of catalysts. The presence of copper enhances the hydrogen production and the best results were obtained using catalysts calcined at 600 °C. Cu has a strong influence on the dispersion of Ni in the catalysts and inhibits NiO from the formation of nickel aluminate even at high calcinations temperatures, which facilitates the formation of the metallic Ni active phase during the subsequent catalyst reduction step. All catalysts tested promote the formation of very long filaments of carbon a few tens of nanometers in diameter and some micrometers long. The structural properties of these carbon filaments highly depend on the presence of Cu:Ni-Cu-Al catalysts promote the formation of a well-ordered graphitic carbon while Ni-Al catalysts enhance the formation of a rather turbostratic carbon.
11. Composition- and temperature-dependent liquid structures in Al-Cu alloys: an ab initio molecular dynamics and x-ray diffraction study
Xiong, L. H.; Wang, X. D.; Cao, Q. P.; Zhang, D. X.; Xie, H. L.; Xiao, T. Q.; Jiang, J. Z.
2017-01-01
The composition- and temperature-dependent liquid structures in eight Alrich-Cu binary alloys (from hypoeutectic Al93Cu7 to hypereutectic Al70Cu30) have been experimentally and computationally studied by x-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. The remarkable agreements of structure factors for all liquid Alrich-Cu alloys obtained from high-temperature high-energy XRD measurements and AIMD simulations have been achieved, which consolidates the analyses of structural evolutions in Alrich-Cu liquids during the cooling processing by AIMD simulations. The heat capacity of liquid Alrich-Cu alloys continuously increases and presents no abnormal peak when reducing the temperature, which differs from the reported prediction for 55-atom Alrich-Cu nanoliquids. The diffusivities of Al and Cu undergo an increasing deviation from Arrhenius behavior by tuning Cu concentration from 7 to 30 atomic percentages, correlated to the local ordering in these liquids by means of coordination number, bond-angle distribution, Honeycutt-Andersen index, bond-orientational order and Voronoi tessellation analyses. Upon cooling, the microstructure of the liquid Alrich-Cu alloys inclines to form Al2Cu crystal-like local atomic ordering, especially in the hypereutectic liquids. The favorable short-range ordering between Cu and Al atoms could cause the non-Arrhenius diffusion behavior.
12. Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates
Wang, Wenliang; Yang, Weijia; Gao, Fangliang; Lin, Yunhao; Li, Guoqiang
2015-03-01
Highly-efficient GaN-based light-emitting diode (LED) wafers have been grown on La0.3Sr1.7AlTaO6 (LSAT) substrates by radio-frequency molecular beam epitaxy (RF-MBE) with optimized growth conditions. The structural properties, surface morphologies, and optoelectronic properties of as-prepared GaN-based LED wafers on LSAT substrates have been characterized in detail. The characterizations have revealed that the full-width at half-maximums (FWHMs) for X-ray rocking curves of GaN(0002) and GaN(10-12) are 190.1 and 210.2 arcsec, respectively, indicating that high crystalline quality GaN films have been obtained. The scanning electron microscopy and atomic force microscopy measurements have shown the very smooth p-GaN surface with the surface root-mean-square (RMS) roughness of 1.3 nm. The measurements of low-temperature and room-temperature photoluminescence help to calculate the internal quantum efficiency of 79.0%. The as-grown GaN-based LED wafers have been made into LED chips with the size of 300 × 300 μm2 by the standard process. The forward voltage, the light output power and the external quantum efficiency for LED chips are 19.6 W, 2.78 V, and 40.2%, respectively, at a current of 20 mA. These results reveal the high optoelectronic properties of GaN-based LEDs on LSAT substrates. This work brings up a broad future application of GaN-based devices.
13. Highly-efficient GaN-based light-emitting diode wafers on La0.3Sr1.7AlTaO6 substrates
PubMed Central
Wang, Wenliang; Yang, Weijia; Gao, Fangliang; Lin, Yunhao; Li, Guoqiang
2015-01-01
Highly-efficient GaN-based light-emitting diode (LED) wafers have been grown on La0.3Sr1.7AlTaO6 (LSAT) substrates by radio-frequency molecular beam epitaxy (RF-MBE) with optimized growth conditions. The structural properties, surface morphologies, and optoelectronic properties of as-prepared GaN-based LED wafers on LSAT substrates have been characterized in detail. The characterizations have revealed that the full-width at half-maximums (FWHMs) for X-ray rocking curves of GaN(0002) and GaN(10-12) are 190.1 and 210.2 arcsec, respectively, indicating that high crystalline quality GaN films have been obtained. The scanning electron microscopy and atomic force microscopy measurements have shown the very smooth p-GaN surface with the surface root-mean-square (RMS) roughness of 1.3 nm. The measurements of low-temperature and room-temperature photoluminescence help to calculate the internal quantum efficiency of 79.0%. The as-grown GaN-based LED wafers have been made into LED chips with the size of 300 × 300 μm2 by the standard process. The forward voltage, the light output power and the external quantum efficiency for LED chips are 19.6 W, 2.78 V, and 40.2%, respectively, at a current of 20 mA. These results reveal the high optoelectronic properties of GaN-based LEDs on LSAT substrates. This work brings up a broad future application of GaN-based devices. PMID:25799042
14. Microstructure and Tensile Properties of Sn-1Ag-0.5Cu Solder Alloy Bearing Al for Electronics Applications
Shnawah, Dhafer Abdul-Ameer; Said, Suhana Binti Mohd; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Hoe, Teh Guan; Che, Fa Xing; Abood, Adnan Naama
2012-08-01
15. Precipitation hardening of an Al-4.2 wt% Mg-0.6 wt% Cu alloy
SciTech Connect
Ratchev, P.; Verlinden, B.; Houtte, P. van; Smet, P. de
1998-06-12
The precipitation hardening of an experimental Al-4.2 wt % Mg-0.6 wt % Cu alloy has been studied. After a first initial jump, the yield strength increases almost linearly with the logarithm of the ageing time and a peak of hardness is reached after 11 days at 180 C. Special attention is given to the precipitation hardening during the early stage of ageing. It has been shown that S{double_prime} phase can be formed heterogeneously on dislocation loops and helices and a new mechanism of precipitation hardening due to this S{double_prime} phase precipitation is proposed. The precipitation of S{double_prime} on dislocations is the predominant cause of strengthening during the initial stage of precipitation hardening (up to 30 min at 180 C). Guinier-Preston-Bagaryatsky (GPB) zones (or better, the recently introduced Cu/Mg clusters) also appear in the initial stage, but their contribution to the hardness, which up to now as considered to be predominant, is shown to be smaller than the one of the S{double_prime} precipitates. Since the density of the S{double_prime} nucleation sites is related to the amount of dislocations, this mechanism is important in the case of a bake hardening treatment when ageing is preceded by cold deformation. Uniform S{double_prime} precipitation has also been found at the later ageing stage, which suggests that the contribution of S{double_prime} to the precipitation hardening at that stage is not less important.
16. Band alignment of epitaxial SrTiO{sub 3} thin films with (LaAlO{sub 3}){sub 0.3}-(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (001)
SciTech Connect
Comes, Ryan B.; Chambers, Scott A.; Xu, Peng; Jalan, Bharat
2015-09-28
SrTiO{sub 3} (STO) epitaxial thin films and heterostructures are of considerable interest due to the wide range of functionalities they exhibit. The alloy perovskite (LaAlO{sub 3}){sub 0.3}-(Sr{sub 2}AlTaO{sub 6}){sub 0.7} (LSAT) is commonly used as a substrate for these material structures due to its structural compatibility with STO and the strain-induced ferroelectric response in STO films grown on LSAT. However, surprisingly little is known about the electronic properties of the STO/LSAT interface despite its potentially important role in affecting the overall electronic structure of system. We examine the band alignment of STO/LSAT heterostructures using x-ray photoelectron spectroscopy for epitaxial STO films deposited using two different molecular beam epitaxy approaches. We find that the valence band offset ranges from +0.2(1) eV to −0.2(1) eV depending on the film surface termination. From these results, we extract a conduction band offset from −2.4(1) eV to −2.8(1) eV, indicating that the conduction band edge is more deeply bound in STO and that LSAT will not act as a sink or trap for electrons in the supported film or multilayer.
17. Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)
SciTech Connect
Comes, Ryan B.; Xu, Peng; Jalan, Bharat; Chambers, Scott A.
2015-09-28
SrTiO3 (STO) epitaxial thin films and heterostructures are of considerable interest due to the wide range of functionalities they exhibit. The alloy perovskite (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) is commonly used as a substrate for these material structures due to its structural compatibility. However, surprisingly little is known about the electronic properties of the STO/LSAT interface despite its potentially important role in affecting the overall electronic structure of system. We examine the band alignment of STO/LSAT heterostructures using x-ray photoelectron spectroscopy for epitaxial STO films deposited using two different molecular beam epitaxy approaches. We find that the valence band offset ranges from +0.2(1) eV to -0.2(1) eV depending on surface conditions for the film and substrate. From these results we extract a conduction band offset from -2.4(1) eV to -2.8(1) eV, indicating that the conduction band edge is more deeply bound in STO and that LSAT will not act as a sink or trap for electrons in the supported film or multilayer.
18. Long-term superelastic cycling at nano-scale in Cu-Al-Ni shape memory alloy micropillars
SciTech Connect
San Juan, J. Gómez-Cortés, J. F.
2014-01-06
Superelastic behavior at nano-scale has been studied along cycling in Cu-Al-Ni shape memory alloy micropillars. Arrays of square micropillars were produced by focused ion beam milling, on slides of [001] oriented Cu-Al-Ni single crystals. Superelastic behavior of micropillars, due to the stress-induced martensitic transformation, has been studied by nano-compression tests during thousand cycles, and its evolution has been followed along cycling. Each pillar has undergone more than thousand cycles without any detrimental evolution. Moreover, we demonstrate that after thousand cycles they exhibit a perfectly reproducible and completely recoverable superelastic behavior.
19. Friction properties of PTFE, h-BN and Al-4%Cu alloy in a vacuum at super low temperature
Friction with ploughing components at super low temperature ina vacuum was studied on the soft plates of PTFE, h-BN and Al-4%Cu alloy sliding with the hard pins of 18-8 stainless steel with a pin-on-plate friction tester. The chief finding was that the friction was affected by low temperature ; for all the same load, friction forces of both of PTFE and h-BN were 16K > 300K, that of Al-4%Cu alloy was 16K <300K.
20. Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg.
PubMed
Ma, Zhipeng; Zhao, Weiwei; Yan, Jiuchun; Li, Dacheng
2011-09-01
Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase.
1. Recovery of Industrial and Recycled Al-Cu Alloys Subjected to Severe Plastic Deformation
Rekik, M. A.; Kassis, K.; Masmoudi, J.; Zghal, S.; Champion, Y.; Njah, N.
2009-11-01
Equal channel angular pressing (ECAP) is a well-known method to obtain high hardness levels through a strong refinement of grains. To obtain fine grains, a subsequent heating is performed after deformation. The main difficulty is to retain a sufficiently small grain size. Alloy purity is an important parameter in recristallization kinetics. In the present work, an industrial and a recycled Al-4%Cu alloys were subjected to ECAP. The evolution of the microstructure of the deformed and annealed alloys was investigated. The alloys exhibit different hardness values for a given equivalent deformation. In industrial alloy, no recovery was observed at low temperatures. On the other hand, enhanced precipitation in this alloy leads to an increase in hardness balancing then softening due to recovery. A substantial decrease in hardness is observed around 250 ∘C and seems to depend on alloy purity.
2. Fracture resistance and fatigue crack growth characteristics of two Al-Cu-Mg-Zr alloys
NASA Technical Reports Server (NTRS)
1992-01-01
The dependence of strength, fracture resistance, and fatigue crack growth rate on the aging conditions of two alloy compositions based on Al-3.7Cu-1.85Mg-0.2Mn is investigated. Mechanical properties were evaluated in two heat treatment conditions and in two orientations (longitudinal and transverse). Compact tension specimens were used to determine fatigue crack growth characteristics and fracture resistance. The aging response was monitored on coupons using hardness measurements determined with a standard Rockwell hardness tester. Fracture resistance is found to increase with increasing yield strength during artificial aging of age-hardenable 2124-Zr alloys processed by powder metallurgy techniques. Fatigue crack growth rate increases with increasing strength. It is argued that these changes are related to deformation modes of the alloys; a homogeneous deformation mode tends to increase fracture resistance and to decrease the resistance to the fatigue crack propagation rate.
3. Three-dimensional Dendritic Needle Network model with application to Al-Cu directional solidification experiments
SciTech Connect
Tourret, D.; Karma, A.; Clarke, A. J.; Gibbs, P. J.; Imhoff, S. D.
2015-06-11
We present a three-dimensional (3D) extension of a previously proposed multi-scale Dendritic Needle Network (DNN) approach for the growth of complex dendritic microstructures. Using a new formulation of the DNN dynamics equations for dendritic paraboloid-branches of a given thickness, one can directly extend the DNN approach to 3D modeling. We validate this new formulation against known scaling laws and analytical solutions that describe the early transient and steady-state growth regimes, respectively. Finally, we compare the predictions of the model to in situ X-ray imaging of Al-Cu alloy solidification experiments. The comparison shows a very good quantitative agreement between 3D simulations and thin sample experiments. It also highlights the importance of full 3D modeling to accurately predict the primary dendrite arm spacing that is significantly over-estimated by 2D simulations.
4. Role of Fe and sign reversal of the Hall coefficient in quasicrystalline Al-Cu-Fe
Lindqvist, P.; Berger, C.; Klein, T.; Lanco, P.; Cyrot-Lackmann, F.; Calvayrac, Y.
1993-07-01
Electronic transport properties were measured for the stable icosahedral phase of Al-Cu-Fe for a large number of high-structural-quality samples of different compositions. At low temperature, the Hall coefficient RH and the conductivity σ are found to best correlate with the Fe content rather than with the electron per atom parameter which is usually used; RH changes sign at a concentration of 12.5 at. % Fe, where σ is at minimum. RH has a strong temperature dependence and can change sign with temperature. These features put the focus on the Fe d states and can be interpreted by a Hume-Rothery type of behavior including the sp-d hybridization effects.
5. Metallographic preparation of Zn-21Al-2Cu alloy for analysis by electron backscatter diffraction (EBSD).
PubMed
Rodríguez-Hernández, M G; Martínez-Flores, E E; Torres-Villaseñor, G; Escalera, M Dolores
2014-08-01
Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.
6. XRMON-SOL: Isothermal equiaxed solidification of a grain refined Al-20 wt%Cu alloy
Murphy, A. G.; Mathiesen, R. H.; Houltz, Y.; Li, J.; Lockowandt, C.; Henriksson, K.; Zimmermann, G.; Melville, N.; Browne, D. J.
2016-04-01
A novel isothermal solidification furnace (XRMON-SOL) has been developed for operation under terrestrial and microgravity conditions, using aluminium-based alloys, in conjunction with real-time in situ X-radiography. The furnace is scheduled to fly on board the MASER 13 Sounding Rocket with a view to investigating isothermal equiaxed solidification under microgravity conditions. The present work provides details of the furnace design as well as detailed analysis of pre-flight terrestrial solidification experiments investigating nucleation and growth characteristics of a thin sample of grain refined Al-20 wt%Cu alloy isothermally solidified at a constant cooling rate of -0.05 K/s. Measurements of nucleation density, nucleation undercooling, grain orientation, grain envelope evolution, primary tip growth velocities, and equiaxed grain interactions are provided. Although the effects of gravity were minimised by choice of sample orientation, we show that such effects can only be eliminated in a microgravity environment.
7. New Fe-Co-Ni-Cu-Al-Ti Alloy for Single-Crystal Permanent Magnets
Belyaev, I. V.; Bazhenov, V. E.; Moiseev, A. V.; Kireev, A. V.
2016-03-01
A new alloy intended for single-crystal permanent magnets has been suggested. The new alloy has been designed based on the well-known Fe-Co-Ni-Cu-Al-Ti system and contains to 1 wt % Hf. The alloy demonstrates an enhanced potential ability for single-crystal forming in the course of unidirectional solidification of ingot. Single-crystal permanent magnets manufactured from this alloy are characterized by a high level of magnetic properties. When designing the new alloy, computer simulation of the phase composition and calculations of solidification parameters of complex metallic systems have been performed using the Thermo-Calc software and calculation and experimental procedures based on quantitative metallographic analysis of quenched structures. After the corresponding heat treatment, the content of high-magnetic phase in the alloy is 10% higher than that in available analogous alloys.
8. Thermophysical Properties Measurements of Zr62Cu20Al10Ni8
NASA Technical Reports Server (NTRS)
Bradshaw, Richard C.; Waren, Mary; Rogers, Jan R.; Rathz, Thomas J.; Gangopadhyay, Anup K.; Kelton, Ken F.; Hyers, Robert W.
2006-01-01
Thermophysical property studies performed at high temperature can prove challenging because of reactivity problems brought on by the elevated temperatures. Contaminants from measuring devices and container walls can cause changes in properties. To prevent this, containerless processing techniques can be employed to isolate a sample during study. A common method used for this is levitation. Typical levitation methods used for containerless processing are, aerodynamically, electromagnetically and electrostatically based. All levitation methods reduce heterogeneous nucleation sites, 'which in turn provide access to metastable undercooled phases. In particular, electrostatic levitation is appealing because sample motion and stirring are minimized; and by combining it with optically based non-contact measuring techniques, many thermophysical properties can be measured. Applying some of these techniques, surface tension, viscosity and density have been measured for the glass forming alloy Zr62Cu20Al10Ni8 and will be presented with a brief overview of the non-contact measuring method used.
9. Microstructure-property relationships in Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 2
NASA Technical Reports Server (NTRS)
Langan, T. J.; Pickens, J. R.
1991-01-01
The microstructure and mechanical properties of the ultrahigh strength Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049, were studied. Specifically, the microstructural features along with tensile strength, weldability, Young's modulus and fracture toughness were studied for Weldalite (tm) 049 type alloys with Li contents ranging from 1.3 to 1.9 wt. pct. The tensile properties of Weldalite 049 and Weldalite 049 reinforced with TiB2 particles fabricated using the XD (tm) process were also evaluated at cryogenic, room, and elevated temperatures. In addition, an experimental alloy, similar in composition to Weldalite 049 but without the Ag+Mg, was fabricated. The microstructure of this alloy was compared with that of Weldalite 049 in the T6 condition to assess the effect of Ag+Mg on nucleation of strengthening phases in the absence of cold work.
10. Direct observation of grain rotations during coarsening of a semisolid Al-Cu alloy
Dake, Jules M.; Oddershede, Jette; Sørensen, Henning O.; Werz, Thomas; Cole Shatto, J.; Uesugi, Kentaro; Schmidt, Søren; Krill, Carl E.
2016-10-01
Sintering is a key technology for processing ceramic and metallic powders into solid objects of complex geometry, particularly in the burgeoning field of energy storage materials. The modeling of sintering processes, however, has not kept pace with applications. Conventional models, which assume ideal arrangements of constituent powders while ignoring their underlying crystallinity, achieve at best a qualitative description of the rearrangement, densification, and coarsening of powder compacts during thermal processing. Treating a semisolid Al-Cu alloy as a model system for late-stage sintering—during which densification plays a subordinate role to coarsening—we have used 3D X-ray diffraction microscopy to track the changes in sample microstructure induced by annealing. The results establish the occurrence of significant particle rotations, driven in part by the dependence of boundary energy on crystallographic misorientation. Evidently, a comprehensive model for sintering must incorporate crystallographic parameters into the thermodynamic driving forces governing microstructural evolution.
11. Three-dimensional Dendritic Needle Network model with application to Al-Cu directional solidification experiments
DOE PAGES
Tourret, D.; Karma, A.; Clarke, A. J.; ...
2015-06-11
We present a three-dimensional (3D) extension of a previously proposed multi-scale Dendritic Needle Network (DNN) approach for the growth of complex dendritic microstructures. Using a new formulation of the DNN dynamics equations for dendritic paraboloid-branches of a given thickness, one can directly extend the DNN approach to 3D modeling. We validate this new formulation against known scaling laws and analytical solutions that describe the early transient and steady-state growth regimes, respectively. Finally, we compare the predictions of the model to in situ X-ray imaging of Al-Cu alloy solidification experiments. The comparison shows a very good quantitative agreement between 3D simulationsmore » and thin sample experiments. It also highlights the importance of full 3D modeling to accurately predict the primary dendrite arm spacing that is significantly over-estimated by 2D simulations.« less
12. Thermoelectric properties of CuAlCh{sub 2} (Ch = S, Se and Te)
SciTech Connect
Gudelli, Vijay Kumar; Kanchana, V.; Vaitheeswaran, G.
2015-06-24
Electronic and thermoelectric properties of ternary chalcopyrite-type CuAlCh{sub 2} (S, Se and Te) were studied using the first principles density functional calculations implemented in the full potential linear augmented plane wave (FP-LAPW) method. The thermoelectric properties are calculated by solving the Boltzmann transport equation within the constant relaxation time approximation. The calculated band gap using the Tran-Blaha modified Becke-Johnson potential (TB-mBJ), of all the compounds are in good agreement with the available experiment and other theoretical reports. Thermoelectric properties like thermopower, electrical conductivity scaled by relaxation time are calculated as a function of carrier concentrations at different temperatures. The calculated thermoelectric properties are compared with the available experiment and other theoretical calculations of similar materials.
13. Reducing the formation of FIB-induced FCC layers on Cu-Zn-Al austenite.
PubMed
Zelaya, Eugenia; Schryvers, Dominique
2011-01-01
The irradiation effects of thinning a sample of a Cu-Zn-Al shape memory alloy to electron transparency by a Ga(+) focused ion beam were investigated. This thinning method was compared with conventional electropolishing and Ar(+) ion milling. No implanted Ga was detected but surface FCC precipitation was found as a result of the focused ion beam sample preparation. Decreasing the irradiation dose by lowering the energy and current of the Ga(+) ions did not lead to a complete disappearance of the FCC structure. The latter could only be removed after gentle Ar(+) ion milling of the sample. It was further concluded that the precipitation of the FCC is independent of the crystallographic orientation of the surface.
14. Fracture resistance and fatigue crack growth characteristics of two Al-Cu-Mg-Zr alloys
SciTech Connect
Sarkar, B.; Lisagor, W.B. NASA, Langley Research Center, Hampton, VI )
1992-01-01
The dependence of strength, fracture resistance, and fatigue crack growth rate on the aging conditions of two alloy compositions based on Al-3.7Cu-1.85Mg-0.2Mn is investigated. Mechanical properties were evaluated in two heat treatment conditions and in two orientations (longitudinal and transverse). Compact tension specimens were used to determine fatigue crack growth characteristics and fracture resistance. The aging response was monitored on coupons using hardness measurements determined with a standard Rockwell hardness tester. Fracture resistance is found to increase with increasing yield strength during artificial aging of age-hardenable 2124-Zr alloys processed by powder metallurgy techniques. Fatigue crack growth rate increases with increasing strength. It is argued that these changes are related to deformation modes of the alloys; a homogeneous deformation mode tends to increase fracture resistance and to decrease the resistance to the fatigue crack propagation rate. 12 refs.
15. Matrix effects in ion-induced emission as observed in Ne collisions with Cu-Mg and Cu-Al alloys
NASA Technical Reports Server (NTRS)
Ferrante, J.; Pepper, S. V.
1983-01-01
Ion induced Auger electron emission is used to study the surfaces of Al, Mg, Cu - 10 at. % Al, Cu - 19.6 at. % Al, and Cu - 7.4 at. % Mg. A neon (Ne) ion beam whose energy is varied from 0.5 to 3 keV is directed at the surface. Excitation of the lighter Ne occurs by the promotion mechanism of Barat and Lichten in asymmetric collisions with Al or Mg atoms. Two principal Auger peaks are observed in the Ne spectrum: one at 22 eV and one at 25 eV. Strong matrix effects are observed in the alloys as a function of energy in which the population of the second peak is greatly enhanced relative to the first over the pure materials. For the pure material over this energy range this ratio is 1.0. For the alloys it can rise to the electronic structure of alloys and to other surface tools such as secondary ion mass spectroscopy.
16. Surface topography and roughness of high-speed milled AlMn1Cu
Wang, Zhenhua; Yuan, Juntang; Yin, Zengbin; Hu, Xiaoqiu
2016-10-01
The aluminum alloy AlMn1Cu has been broadly applied for functional parts production because of its good properties. But few researches about the machining mechanism and the surface roughness were reported. The high-speed milling experiments are carried out in order to improve the machining quality and reveal the machining mechanism. The typical topography features of machined surface are observed by scan electron microscope(SEM). The results show that the milled surface topography is mainly characterized by the plastic shearing deformation surface and material piling zone. The material flows plastically along the end cutting edge of the flat-end milling tool and meanwhile is extruded by the end cutting edge, resulting in that materials partly adhere to the machined surface and form the material piling zone. As the depth of cut and the feed per tooth increase, the plastic flow of materials is strengthened and the machined surface becomes rougher. However, as the cutting speed increases, the plastic flow of materials is weakened and the milled surface becomes smoother. The cutting parameters (e.g. cutting speed, feed per tooth and depth of cut) influencing the surface roughness are analyzed. It can be concluded that the roughness of the machined surface formed by the end cutting edge is less than that by the cylindrical cutting edge when a cylindrical flat-end mill tool is used for milling. The proposed research provides the typical topography features of machined surface of the anti-rust aluminum alloy AlMn1Cu in high speed milling.
17. Shape memory properties and microstructural evolution of rapidly solidified CuAlBe alloys
SciTech Connect
Ergen, Semra; Uzun, Orhan; Yilmaz, Fikret; Kiliçaslan, M. Fatih
2013-06-15
In this work, the effects of Be addition on the microstructure and phase transformation temperatures of Cu–12Al–xBe (x = 0.4, 0.5 and 0.6 wt.%) shape memory alloys fabricated by using the arc-melting and melt-spinning techniques have been investigated. X-ray diffraction analysis revealed that the arc-melted alloys consisted of austenitic β{sub 1}, martensitic β{sub 1}′ and γ{sub 2} precipitate phases, whereas melt-spun ribbons were composed of a fully martensitic phase. The average grain size of martensitic phases in melt-spun ribbons was determined by electron microscopy images, showing a decrease with increasing Beryllium (Be) amount. Moreover, it was found that the Be addition in the arc-melted alloys had a distinct effect on the morphology of the γ{sub 2} precipitate phase. Transmission electron microscopy analysis showed that the thickness of martensitic plates in the melt-spun ribbons reduced with increasing Be addition. In a differential scanning calorimeter analysis, no martensitic transformation (M{sub s}) peak was observed in arc-melted alloys, but it was clearly detected in melt-spun ribbons, in which M{sub s} decreased dramatically with increasing Be addition. The improvement in the shape memory ability of melt-spun ribbons was explained in terms of the refinement in grain size and martensitic plates. - Highlights: • The CuAlBe SMAs were produced by means of arc-melter and melt-spinner techniques. • MT was directly obtained in melt-spuns without any intermediate process. • The transformation temperatures decreased with increasing Be amount. • The thickness of martensitic plates in the ribbons reduced with increasing Be. • SMP of CuAl was improved by the addition of Be together with rapid solidification.
18. Temperature effects on the deformation and fracture of Al-Li-Cu-In alloys
NASA Technical Reports Server (NTRS)
Wagner, John A.; Gangloff, Richard P.
1991-01-01
The crack initiation and growth fracture resistance of Al-Cu-Li and Al-Cu-Li-In alloys were characterized and optimized for cryogenic tank applications. Presently, the effects of stress state and temperature is being determined on the fracture toughness and fracture mechanisms of commercially available Vintage 3 2090-T81 and experimental 2090+In-T6. Precracked J-integral specimens of both alloys were tested at ambient and cryogenic temperatures in the plane stress and plane strain conditions. Considering ambient temperature, results showed that 2090-T81 exhibited the highest toughness in both plane strain and plane stress conditions. For the plane strain condition, reasonable crack initiation and growth toughness of 1090-T81 are associated with a significant amount of delamination and transgranular fracture. Plane stress toughnesses were higher and fracture was characterized by shear cracking with minimal delaminations. In comparisons, the fracture behavior of 2090+In-T6 is significantly degraded by subgrain boundary precipitation. Toughness is low and characterized by intersubgranular fracture with no delamination in the plane stress or plane strain conditions. Intersubgranular cracking is a low energy event which presumably occurs prior to the onset of slip band cracking. Copious grain boundary precipitation is atypical of commercially available 2090. At cryogenic temperatures, both alloys exhibit increased yield strength, toughness, and amount of delamination and shear cracking. The change in fracture mode of 2090+In-T6 from intersubgranular cracking at ambient temperature to a combination of intersubgranular cracking, shear cracking, and delamination at cryogenic temperature is the subject of further investigation.
19. Effect of a prior stretch on the aging response of an Al-Cu-Li-Ag-Mg-Zr alloy
NASA Technical Reports Server (NTRS)
Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.
1991-01-01
Recently, a family of Al-Cu-Li alloys containing minor amounts of Ag, Mg, and Zr and having desirable combinations of strength and toughness were developed. The Weldalite (trademark) alloys exhibit a unique characteristic in that with or without a prior stretch, they obtain significant strength-ductility combinations upon natural and artificial aging. The ultra-high strength (approximately 690 MPa yield strength) in the peak-aged tempers (T6 and T8) were primarily attributed to the extremely fine T(sub 1) (Al2CuLi) or T(sub 1)-type precipitates that occur in these alloys during artificial aging, whereas the significant natural aging response observed is attributed to strengthening from delta prime (Al3Li) and GP zones. In recent work, the aging behavior of an Al-Cu-Li-Ag-Mg alloy without a prior stretch was followed microstructurally from the T4 to the T6 condition. Commercial extrusions, rolled plates, and sheets of Al-Cu-Li alloys are typically subjected to a stretching operation before artificial aging to straighten the extrusions and, more importantly, introduce dislocations to simulate precipitation of strengthening phases such as T(sub 1) by providing relatively low-energy nucleation sites. The goals of this study are to examine the microstructure that evolves during aging of an alloy that was stretch after solution treatment and to compare the observations with those for the unstretched alloy.
20. Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED Studies
SciTech Connect
Cai, T.; Shi, F.; Shen, Z.; Gierer, M.; Goldman, A.I.; Kramer, M.J.; Jenks, C.J.; Lograsso, T.A.; Delaney, D.W.; Thiel, P.A.; Van, M.A.
2001-04-15
We investigate the atomic structure of the fivefold surface of an icosahedral Al-Cu-Fe alloy, using scanning tunneling microscopy (STM) imaging and a special dynamical low energy-electron diffraction (LEED) method. STM indicates that the step heights adopt (primarily) two values in the ratio of tau, but the spatial distribution of these two values does not follow a Fibonacci sequence, thus breaking the ideal bulk-like quasicrystalline layer stacking order perpendicular to the surface. The appearance of screw dislocations in the STM images is another indication of imperfect quasicrystallinity. On the other hand, the LEED analysis, which was successfully applied to Al-Pd-Mn in a previous study, is equally successful for Al-Cu-Fe. Similar structural features are found for both materials, in particular for interlayer relaxations and surface terminations. Although there is no structural periodicity, there are clear atomic planes in the bulk of the quasicrystal, some of which can be grouped in recurring patterns. The surface tends to form between these grouped layers in both alloys. For Al-Cu-Fe, the step heights measured by STM are consistent with the thicknesses of the grouped layers favored in LEED. These results suggest that the fivefold Al-Cu-Fe surface exhibits a quasicrystalline layering structure, but with stacking defects.
1. Epitaxial growth of homogeneous single-crystalline AlN films on single-crystalline Cu (1 1 1) substrates
Wang, Wenliang; Yang, Weijia; Liu, Zuolian; Lin, Yunhao; Zhou, Shizhong; Qian, Huirong; Gao, Fangliang; Yang, Hui; Li, Guoqiang
2014-03-01
The homogeneous and crack free single-crystalline AlN thin films have been epitaxially grown on single-crystalline Cu (1 1 1) substrates with an in-plane alignment of AlN [11-20]//Cu [1-10] by pulsed laser deposition (PLD) technology with an integrated laser rastering program. The as-grown AlN films are studied by spectroscopic ellipsometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), polarized light microscopy, high-resolution X-ray diffraction, and high-resolution transmission electron microscopy (HRTEM). The spectroscopic ellipsometry reveals the excellent thickness uniformity of as-grown AlN films on the Cu (1 1 1) substrates with a root-mean-square (RMS) thickness inhomogeneity less than 2.6%. AFM and FESEM measurements indicate that very smooth and flat surface AlN films are obtained with a surface RMS roughness of 2.3 nm. The X-ray reflectivity image illustrates that there is a maximum of 1.2 nm thick interfacial layer existing between the as-grown AlN and Cu (1 1 1) substrates and is confirmed by HRTEM measurement, and reciprocal space mapping shows that almost fully relaxed AlN films are achieved only with a compressive strain of 0.48% within ∼321 nm thick films. This work demonstrates a possibility to obtain homogeneous and crack free single-crystalline AlN films on metallic substrates by PLD with optimized laser rastering program, and brings up a broad prospect for the application of acoustic filters that require abrupt hetero-interfaces between the AlN films and the metallic electrodes.
2. Chemical composition characterization of Ca3Ta(Ga0.5Al0.5)3Si2O14 single crystal by the line-focus-beam ultrasonic material characterization system
Ohashi, Yuji; Kudo, Tetsuo; Yokota, Yuui; Shoji, Yasuhiro; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira
2016-10-01
A new method for evaluation of homogeneity of Ca3Ta(Ga0.5Al0.5)3Si2O14 (CTGAS) single crystals was established based on leaky surface acoustic wave (LSAW) velocity measurements performed by the line-focus-beam ultrasonic material characterization (LFB-UMC) system. Three plate specimens cut perpendicular to X-, Y-, and Z-axes were prepared from the CTGAS crystal ingot and LSAW velocity distributions were examined for these specimens. LSAW velocity changes due to Al-substitution effect were successfully extracted by using a relationship between two LSAW velocities propagating along different directions for Ca3TaGa3Si2O14 (CTGS) and Al-substituted CTGS. Comparison of measured LSAW velocities and the results of chemical composition analysis performed by electron probe microanalysis (EPMA) demonstrated that LSAW velocity is mainly affected by Al-content change in CTGAS. Maximum velocity variation was observed in radial direction of the crystal ingot through the Z-axis propagating LSAW velocity measurements for Y-cut CTGAS specimen corresponding to Al-content change of 0.226 mol%. Accuracy of evaluation of Al content by velocity measurement for Y-cut Z-propagating LSAW is estimated to be ±0.0047 mol% and is superior to that by EPMA.
3. Influence of nano-Al2O3-reinforced oxide-dispersion-strengthened Cu on the mechanical and tribological properties of Cu-based composites
Zhao, Xiang; Guo, Lei-chen; Zhang, Long; Jia, Ting-ting; Chen, Cun-guang; Hao, Jun-jie; Shao, Hui-ping; Guo, Zhi-meng; Luo, Ji; Sun, Jun-bin
2016-12-01
The mechanical and tribological properties of Cu-based powder metallurgy (P/M) friction composites containing 10wt%-50wt% oxide-dispersion-strengthened (ODS) Cu reinforced with nano-Al2O3 were investigated. Additionally, the friction and wear behaviors as well as the wear mechanism of the Cu-based composites were characterized by scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS) elemental mapping. The results indicated that the Cu-based friction composite containing 30wt% ODS Cu exhibited the highest hardness and shear strength. The average and instantaneous friction coefficient curves of this sample, when operated in a high-speed train at a speed of 300 km/h, were similar to those of a commercial disc brake pad produced by Knorr-Bremse AG (Germany). Additionally, the lowest linear wear loss of the obtained samples was (0.008 ± 0.001) mm per time per face, which is much lower than that of the Knorr-Bremse pad ((0.01 ± 0.001) mm). The excellent performance of the developed pad is a consequence of the formation of a dense oxide composite layer and its close combination with the pad body.
4. Obtention of low oxidation states of copper from Cu 2+-Al 3+ layered double hydroxides containing organic sulfonates in the interlayer
Trujillano, Raquel; Holgado, María Jesús; Rives, Vicente
2009-03-01
A series of hydrotalcite-type compounds containing Cu(II) and Al(III) in the layers, and carbonate or different alkylsulfonates in the interlayer, have been prepared and studied. Calcination of these solids gives rise to formation of metallic copper and Cu 2+ and Cu + oxides or sulfates, depending on the calcination temperature and on the precise nature of the interlayer alkylsulfonate.
5. Brazing microstructure of Ti-6Al-6V-2Sn with Ti-Zr-Cu-Ni filler metal
SciTech Connect
Hsieh, K.C.; Kao, P.W.; Shu, M.F.
1994-12-31
Titanium and its alloys have been widely used in the aerospace industry since they have high specific strength and high corrosion resistance. The brazing of titanium is beneficial to join many contact areas simultaneously without severe distortion. The purpose of this study is to investigate the brazing microstructures under different brazing conditions with several Ti-Zr-Cu-Ni filler alloys. In our previous studies, the brazing microstructure of Ti-6Al-4V with Ti-Cu-Ni filler metal have been reported. Since Ti-6Al-6V-2Sn alloy has lower b-transus, the Ti-Cu-Ni filler alloy cannot successfully apply the brazing work. Several Ti-Zr-Cu-Ni alloys were prepared in powder form and pre-alloy form to perform the brazing of Ti-6Al-6V-2Sn at 870{degrees}C. The brazing microstructures are examined under optical metallograph, scanning electron microscopy (SEM), and X-ray analysis. The contents of this report include (1) DTA and phase analysis of Ti-Zr-Cu-Ni filler metals, (2) the brazing microstructure, and (3) the shear test result.
6. Enhancement on wettability and intermetallic compound formation with an addition of Al on Sn-0.7Cu lead-free solder fabricated via powder metallurgy method
Adli, Nisrin; Razak, Nurul Razliana Abdul; Saud, Norainiza
2016-07-01
Due to the toxicity of lead (Pb), the exploration of another possibility for lead-free solder is necessary. Nowadays, SnCu alloys are being established as one of the lead-free solder alternatives. In this study, Sn-0.7Cu lead-free solder with an addition of 1wt% and 5wt% Al were investigated by using powder metallurgy method. The effect of Al addition on the wettability and intermetallic compound thickness (IMC) of Sn-0.7Cu-Al lead-free solder were appraised. Results showed that Al having a high potential to enhance Sn-0.7Cu lead-free solder due to its good wetting and reduction of IMC thickness. The contact angle and IMC of the Sn-0.7Cu-Al lead-free solder were decreased by 14.32% and 40% as the Al content increased from 1 wt% to 5 wt%.
7. Residual Stress Development in CU Thin Films with and Without AlN Passivation by Cyclic Plane Bending
Shinohara, Mitsuhiko; Hanabusa, Takao; Kusaka, Kazuya
Since the thin film technology is applied to micro-machines, MEMS (micro electro-mechanical system), optical devices and others, the evaluation of mechanical properties in thin films becomes to be important. On the other hand, there are differences in mechanical properties between bulk materials and thin films, but studies in this field have not yet been made enough. The present paper reports on the evaluation of the mechanical properties of Cu thin films with and without AlN passivation layer. Specimens with different thickness of Cu film were subjected to cyclic plane bending fatigue test. Residual stresses developed in the Cu films were measured in a sequence of bending cycles using X-ray diffraction method in order to understand the effect of film thickness and passivation layer on mechanical properties of Cu thin films.
8. Characteristics of Friction Welding Between Solid Bar of 6061 Al Alloy and Pipe of Al-Si12CuNi Al Cast Alloy
Kimura, M.; Sakaguchi, H.; Kusaka, M.; Kaizu, K.; Takahashi, T.
2015-11-01
This paper describes the characteristics of friction welding between a solid bar of 6061 Al alloy and a pipe of Al-Si12CuNi (AC8A) Al cast alloy. When the joint was made by a continuous drive friction welding machine (conventional method), the AC8A portion of the joint showed heavy deformation and the AA6061 showed minimal deformation. In particular, the joint could not be successfully made with following conditions, because AC8A pipe side crushed due to insufficient friction heat or high pressure: a short friction time such as 0.3 s, high friction pressure such as 100 MPa, or high forge pressure such as 150 MPa. The heavy deformation of AC8A side was caused by increasing friction torque during braking. To prevent braking deformation until rotation stops, a joint was made by a continuous drive friction welding machine that has an electromagnetic clutch. When the clutch was released, the relative speed between both specimens simultaneously decreased to zero. When the joint was made with friction pressure of 25 MPa, friction time of 0.3 s, and forge pressure of 125 MPa, the joining could be successfully achieved and that had approximately 16% efficiency. In addition, when the joint was made with friction pressure of 25 MPa, friction time of 0.7 s, and forge pressure of 125 MPa, it had approximately 54% efficiency. However, all joints showed the fracture between the traveled weld interface and the AC8A side, because the weld interface traveled in the longitudinal direction of AC8A side from the first contacted position of both weld faying surfaces. Hence, it was clarified that the friction welding between a solid bar of AA6061 and a cast pipe of AC8A was not desirable since the traveling phenomena of the weld interface were caused by the combination of the shapes of the friction welding specimens.
9. Crystal structure and anisotropic magnetic properties of new ferromagnetic Kondo lattice compound Ce(Cu,Al,Si)2
Maurya, A.; Thamizhavel, A.; Dhar, S. K.; Provino, A.; Pani, M.; Costa, G. A.
2017-03-01
Single crystals of the new compound CeCu0.18Al0.24Si1.58 have been grown by high-temperature solution growth method using a eutectic Al-Si mixture as flux. This compound is derived from the binary CeSi2 (tetragonal α-ThSi2-type, Pearson symbol tI12, space group I41/amd) obtained by partial substitution of Si by Cu and Al atoms but showing full occupation of the Si crystal site (8e). While CeSi2 is a well-known valence-fluctuating paramagnetic compound, the CeCu0.18Al0.24Si1.58 phase orders ferromagnetically at TC=9.3 K. At low temperatures the easy-axis of magnetization is along the a-axis, which re-orients itself along the c-axis above 30 K. The presence of hysteresis in the magnetization curve, negative temperature coefficient of resistivity at high temperatures, reduced jump in the heat capacity and a relatively lower entropy released up to the ordering temperature, and enhanced Sommerfeld coefficient (≈100 mJ/mol K2) show that CeCu0.18Al0.24Si1.58 is a Kondo lattice ferromagnetic, moderate heavy fermion compound. Analysis of the high temperature heat capacity data in the paramagnetic region lets us infer that the crystal electric field split doublet levels are located at 178 and 357 K, respectively, and Kondo temperature (8.4 K) is of the order of TC in CeCu0.18Al0.24Si1.58.
10. Bond ionicities in CuBC2 chalcogenides (B=Al, Ga, In; C=S, Se, Te)
Merino, J. M.; Díaz, R.; León, M.
2000-04-01
The bond ionicities, fi,Cu-C and fi,BC of several CuBC2 (B=Al, Ga, In, and C=S, Se, Te) chalcopyrite compounds are estimated by means of the Phillips-Van Vechten dielectric theory for binary tetrahedral compounds and Levine's extension to multibond crystals in the same way as Neumann [Crystal Res. Technol. 18, 1299 (1983)]. The influence of Cu 3d electrons has been taken into account considering Jaffe-Zunger [Phys. Rev. B 29, 1882 (1984)] band-structure calculations in chalcopyrite compounds, and performing a simple extrapolation for Te compounds. The Cu-C bond susceptibilities have been estimated from the static dielectric constant values obtained by Márquez and Rincón [Phys. Status Solidi B 191, 115 (1995)], and a set of Cu-C bond susceptibilities is proposed. The evaluated fi,Cu-C bond ionicities were found to increase with the atomic fractional coordinate of the C atom, x[anion], indicating that the anion position is a good estimation of the Cu-C bond ionicity.
11. Irradiation effect of swift heavy ion for Zr50Cu40Al10 bulk glassy alloy
Onodera, Naoto; Ishii, Akito; Ishii, Kouji; Iwase, Akihiro; Yokoyama, Yoshihiko; Saitoh, Yuichi; Ishikawa, Norito; Yabuuchi, Atsushi; Hori, Fuminobu
2013-11-01
It has been reported that heavy ion irradiation causes softening in some cases of Zr-based bulk metallic glass alloys. However, the fundamental mechanisms of such softening have not been clarified yet. In this study, Zr50Cu40Al10 bulk glassy alloys were irradiated with heavy ions of 10 MeV I at room temperature. The maximum fluence was 3 × 1014 ions/cm2. The positron annihilation measurements have performed before and after irradiation to investigate changes in free volume. We discuss the relationship between the energy loss and local open volume change after 10 MeV I irradiation compared with those obtained for 200 MeV Xe and 5 MeV Al. The energy loss analysis in ion irradiation for the positron lifetime has revealed that the decreasing trend of positron lifetime is well expressed as a function of total electronic energy deposition rather than total elastic energy deposition. It means that the positron lifetime change by the irradiation has a relationship with the inelastic collisions with electrons during heavy ion irradiation.
12. In-Situ Observation of Directional Solidifications of Al-Cu Alloys During Parabolic Flight Campaigns
Abou-Khalil, L.; Salloum-Abou-Jaoude, G.; Reinhart, G.; Pickmann, C.; Zimmermann, G.; Houltz, Y.; Li, J.; Janson, O.; Nguyen-Thi, H.
2015-09-01
It is well known that the final properties of materials are strongly related to the microstructures formed during growth and to the accompanying segregation, both being very sensitive to the natural hydrodynamic movements in the melt induced by gravity. Therefore, a deeper understanding of gravity effects on the solidification microstructure is of great importance for industrial applications. In the framework of the ESA-MAP project entitled XRMON (in-situ X-Ray MONitoring of advanced metallurgical processes under microgravity and terrestrial conditions), directional solidification experiments with in situ X-ray radiography were carried out during the 60th and 61st ESA — PF campaigns onboard the Airbus A300 operated by Novespace. Parabolic flights offer several successions of periods with normal gravity between two parabolas, and hyper gravity and microgravity during each parabola, which allows the impact of gravity level variations on the solidification microstructures to be investigated. For this purpose, a dedicated apparatus was designed and developed in collaboration with SSC (Swedish Space Corporation). XRMON-PFF (Parabolic Flight Facility) includes a Bridgman furnace dedicated to the solidification of Al-based alloys with an X-ray device that enables in situ characterization. Columnar and/or equiaxed growth of refined and non-refined Al2Owt.%Cu alloys were investigated and X-ray radiography was successfully used to assess the effect of periodic variations of the gravity level on the solidification microstructure formation. Preliminary results confirmed the strong influence of gravity on the solidification microstructure development.
13. Crystal growth and transport properties of CuAlO2 single crystal
Brahimi, R.; Rekhila, G.; Trari, M.; Bessekhouad, Y.
2014-12-01
The transport properties of the delafossite CuAlO2 single crystal, grown by the flux method, are confined in ∞[AlO2] layers extending in the (001) plans. The dielectric properties are measured up to 490 K in the frequency range (102-105 Hz). The small variation of the dielectric loss tan(δ) is attributed to the wide space charge region. The linear plot log (conductivity) vs. 1000/ T follows an Arrhenius type law and the results are discussed in terms of electron hopping among localized states. The activation energy (0.18 eV) gives an effective mass of 16 m 0 indicating that the levels in the vicinity of the Fermi level are strongly localized. Hence, the increase of the conductivity (σ) results from a thermal activation of the mobility (μ300 K = 1.2 × 10-5 cm-2 V-1 s-1). The sign of hole like small polarons is that of p type carriers originating from oxygen intercalation. The thermopower is little temperature dependent and characteristic of non degenerate conductivity with a low holes concentration and a large concentration of surface states within the gap region.
14. Characterization of Al-Cu-Li Alloy 2090 Near Net Shape Extrusion
NASA Technical Reports Server (NTRS)
Birt, M. J.; Domack, M. S.; Hafley, R. A.; Pollock, W. D.
1998-01-01
Aluminum-lithium (Al-Li) alloys near net shape extrusions are being evaluated for potential application in launch vehicle structures. The objective of this study was to determine tensile and fracture properties, corrosion resistance, and weldability of integrally stiffened panels of Al-Cu-Li alloy 2090 in the T8 temper. The microstructure was pre-dominantly unrecrystallized. Texture analyses revealed the presence of fiber components in the stiffeners and a combination of fiber and rolling components in the skin. Variations in grain morphology and texture through the extruded cross section were correlated with the tensile, fracture, and corrosion behavior. Tensile strengths at room and cryogenic temperatures of the 2090 extrusions were similar to other 2090 product forms and were higher than 2219-T87, the primary structural material in the Space Shuttle external tank; however, ductilities were lower. The fracture resistance of the 2090 extrusion was lower than 2219-T87 plate at room temperature. At cryogenic temperatures, tensile ductility and fracture behavior of the 2090 extrusion were similar to other 2090 product forms but were lower than 2219-T87 plate. The exfoliation and stress corrosion resistance of the 2090 extrusion compared favorably with the characteristics of other 2090 product forms. The weldability and weldment properties of the extrusions were similar to 2090 and 2219 plates.
15. High-efficiency GaAs/CuInSe2 and AlGaAs/CuInSe2 thin-film tandem solar cells
Gale, R. P.; McClelland, R. W.; Dingle, B. D.; Gormley, J. V.; Burgess, R. M.
Tandem cell throughput has been increased, and quantities of cells that produce tens of watts of power in total were fabricated. An improved efficiency of 23.1 percent AM0/one sun at 28 C has been obtained for 4-sq cm tandem cells. The mechanically stacked tandem cells consist of an n(+):AlGaAs/n:GaAs/p:GaAs/p(+):AlGaAs thin-film top cell and an n(+):CdZnS/p:CuInSe2 thin-film bottom cell. In addition to being highly efficient, the cells are light in weight and radiation resistant. Large numbers of tandem cells have been completed, and individual cell performances exceeded 20 percent for the GaAs top cell and 3 percent for the CuInSe2 (CIS) bottom cell. To attain increased radiation resistance and even higher end-of-life efficiencies, the use of an AlGaAs high-bandgap cell for the upper cell was investigated. Large areas of thin-film AlGaAs were produced using the CLEFT process, and filters to simulate AlGaAs cell structures to be used over the CIS cells were fabricated. CIS cells have been tested under these filters. Results of these measurements indicate that significantly higher efficiencies can be expected from the lower cell in this configuration, and very high end-of-life efficiencies are possible with this approach.
16. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting
Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan
2016-04-01
The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.
17. Kinetics of hydrogen production of methanol reformation using Cu/ZnO/Al2O3 catalyst.
PubMed
Wu, Ho-Shing; Chung, Shun-Chang
2007-01-01
The catalytic performance of methanol reformation using Cu/ZnO/Al2O3 was investigated at low temperature. The operation conditions, such as composition of Cu, Zn, and Al, temperature, molar ratio of H2O/CH3OH, weight hourly space velocity, catalyst weight, and kind and flow rate of carrier gas (helium and air), were evaluated to obtain the optimum reaction condition. The catalysts were prepared by oxalic coprecipitation, coprecipitation, and polyol method. The weight composition of Cu, Zn, and Al prepared by oxalic coprecipitation was 15:15:5 by high-throughput screening of combinatorial chemistry method, which was the best Cu/ZnO/Al2O3 catalyst. The prepared catalysts showed high activity and selectivity towards hydrogen formation. The methanol conversion, production rate, and volumetric percentage of hydrogen using this best catalyst were larger than 95%, 0.65 mol/h x g and 59%, respectively, and the CO volumetric percentage was smaller than 0.22% when the reaction temperature was 240 degrees C. The size and dispersity of copper, and the activity and turnover frequency of the catalyst were calculated as well.
18. Site occupation, phase stability, crystal and electronic structures of the doped S phase (Al2CuMg)
Gu, Jianglong; Gu, Huimin; Zhai, Yuchun; Ma, Peihua
2016-07-01
The S phase (Al2CuMg) is an important strengthening phase for the Al-Cu-Mg alloys, which are widely used in the aerospace and transportation industries. The commonly added alloying elements (Mn, Ti, Zr) and the impurity elements (Fe and Si) in the Al-Cu-Mg alloys are always found in the S phase. First-principles calculations based on the density functional theory (DFT) were used to investigate the influence of doping Mn, Ti, Zr, Fe and Si elements on the S phase. Key findings demonstrated that these elements prefer to occupy different atomic sites in the S phase. Ti and Zr improved the structural stability of the S phase. The bulk modulus of the Fe, Si, Ti and Zr doped S phases becomes larger than that of the pure S phase. Both the crystal and electronic structures of the S phase are affected by the dopants. The results of this study provide a better theoretical understanding of the S phase, providing guidance for improved composition design and performance optimization of Al-Cu-Mg alloys.
19. Epoxidation of alkenes through oxygen activation over a bifunctional CuO/Al2O3 catalyst.
PubMed
Scotti, Nicola; Ravasio, Nicoletta; Zaccheria, Federica; Psaro, Rinaldo; Evangelisti, Claudio
2013-03-07
The epoxidation of alkenes was carried out over a CuO/Al(2)O(3) catalyst using cumene as an oxygen carrier, through a one-pot reaction, giving high conversion and selectivity with different substrates. Trans-β-methylstyrene gave the corresponding epoxide in 95% yield after 3 h.
20. The evolution of interface microstructure in a ZrO[sub 2]/Ag-Cu-Al-Ti system
SciTech Connect
Lee, Youngmin; Yu, Jin )
1993-08-01
Among ceramic/metal (C/M) joining technologies, the active filler metal method has been studied extensively due to the simple brazing process and excellent joint strength. Active metal elements, typically Ti, are intentionally added to braze alloys to enhance the formation of reaction products between the ceramic and the braze metal at the C/M interface. In the brazing of Al[sub 2]O[sub 3] with the Ag-Cu-Ti filler metal, reaction products such as [gamma]-TiO, Cu[sub 2](Ti, Al)[sub 4]O, Ti[sub 3](Cu[sub 0.76]Al[sub 0.18]Sn[sub 0.06])[sub 3]O were found, while products such as Ti[sub 5]Si[sub 3] and TiN formed in the brazing of Si[sub 3]N[sub 4]. The presence of reaction layers at the C/M interface influences the interface strength in a complex way. In Cu/Al[sub 2]O[sub 3], Co/Al[sub 2]O[sub 3], Ni/Al[sub 2]O[sub 3], and Cu/diamond systems, maxima of joint strength were observed at some intermediate Ti addition, while the flexural strength decreased substantially with the thickening of the TiO layer in a ZrO[sub 2]/Ag-Cu-Sn-Ti system. Thus, composition of the braze alloy (particularly, the content of the active metal), process conditions such as brazing temperature and time, microstructure and mechanical properties of reaction products at the C/M interfaces, interfacial chemistry, and residual stress are primary factors to be studied in order to understand the strengths of the C/M interfaces systematically. In the present and the following papers, evolutions of interfacial microstructures at various brazing conditions, and corresponding interface strengths are reported, respectively, for a ZrO[sub 2]/Ag-Cu-Al-Ti system.
1. An experimental investigation of innovative bridge columns with engineered cementitious composites and Cu-Al-Mn super-elastic alloys
Hosseini, F.; Gencturk, B.; Lahpour, S.; Ibague Gil, D.
2015-08-01
Recent strong earthquakes have shown that reinforced concrete (RC) bridge columns constructed using conventional materials and techniques suffer from major damage and permanent deformations. The yielding of the longitudinal reinforcement as the main source of energy absorption, and cracking and spalling of concrete results in a dysfunctional bridge structure that does not support the post-disaster recovery efforts. This paper investigates the use of engineered cementitious composites (ECCs) and Cu-Al-Mn super-elastic alloys (SEAs) to improve the performance of bridge columns under seismic loads. A new column design is proposed, which is composed of a pre-fabricated ECC tube that encompasses the longitudinal and transverse steel reinforcement (rebar). The rebar in the plastic hinge region of the cantilever columns was totally or partially replaced with Cu-Al-Mn SEA bars. The tube was filled with conventional concrete after it was placed inside the rebar cage of the foundation. ECC exhibits superior tensile ductility, bonding with steel, energy absorption and shear resistance, in addition to lower permeability and reduced crack widths compared to conventional concrete. Cu-Al-Mn SEA bars are capable of recovering large inelastic deformations exceeding 12% strain. The proposed approach capitalizes on the deformability of ECC with reduced damage, and the energy absorption capacity of Cu-Al-Mn SEA bars without permanent deformation. A total of six column specimens were constructed and tested under simulated seismic loading. The number of rebars replaced with Cu-Al-Mn SEA bars, ECC mixture design, and the ratio of the concrete core area to total column cross-sectional area were the variables investigated in the test program. A comparison of the results indicated that the proposed concept with no Cu-Al-Mn SEA bars provides higher lateral strength, similar energy absorption and reduced damage compared to conventional RC columns; however, similar to a conventional column, it
2. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles
Dutkiewicz, Jan; Rogal, Łukasz; Wajda, Wojciech; Kukuła-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas
2015-06-01
The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 μm, so the powder was sieved to obtain maximum size of 60 μm. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 °C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.
3. Microstructure and mechanical properties investigation of in situ TiB2 and ZrB2 reinforced Al-4Cu composites
Lutfi Anis, Ahmad; Ramli, Rosmamuhammadani; Darham, Widyani; Zakaria, Azlan; Talari, Mahesh Kumar
2016-02-01
Conventional Al-Cu alloys exhibit coarse grain structure leading to inferior mechanical properties in as-cast condition. Expensive thermo-mechanical treatments are needed to improve microstructure and corresponding mechanical properties. In situ Al-based composites were developed to improve mechanical properties by dispersion strengthening and grain refinement obtained by the presence of particulates in the melt during solidification. In this work Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 in situ composites were prepared by liquid casting method. XRD, electron microscopy and mechanical tests were performed on suitably sectioned and metallographically prepared surfaces to investigate the phase distribution, hardness and tensile properties. It was found that the reinforcement particles were segregated along the grain boundaries of Al dendrites. Tensile fracture morphology for both Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 were analyzed and compared to determine the fracture propagation mechanism in the composites. Al-4Cu-3ZrB2 in situ composites displayed higher strength and hardness compared to Al-4Cu-3TiB2 which could be ascribed to the stronger interfacial bonding between the Al dendrites and ZrB2 particulates as evidenced from fractographs.
4. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows
Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.
2016-12-01
Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu6Sn5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu6Sn5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu6Sn5 observed, while in the melt spun alloy, Cu6Sn5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu6Sn5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. The reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu6Sn5 was maintained for both alloys.
5. Interfacial Reactions of Zn-Al Alloys with Na Addition on Cu Substrate During Spreading Test and After Aging Treatments
Gancarz, Tomasz; Pstruś, Janusz; Berent, Katarzyna
2016-08-01
Spreading tests for Cu substrate with Zn-Al eutectic-based alloys with 0.2, 0.5, and 1.0 wt.% of Na were studied using the sessile drop method in the presence of QJ201 flux. Spreading tests were performed for 1, 3, 8, 15, 30, and 60 min of contact, at the temperatures of 475, 500, 525, and 550 °C. After cleaning the flux residue from solidified samples, the spreading area of Zn-Al + Na on Cu was determined in accordance with ISO 9455-10:2013-03. Selected, solidified solder-substrate couples were cross-sectioned and subjected to scanning electron microscopy of the interfacial microstructure. The experiment was designed to demonstrate the effect of Na addition on the kinetics of formation and growth of CuZn, Cu5Zn8, and CuZn4 phases, which were identified using x-ray diffraction and energy-dispersive spectroscopy analysis. The addition of Na to eutectic Zn-Al caused the spreading area to decrease and the thickness of intermetallic compound layers at the interface to reduce. Samples after the spreading test at 500 °C for 1 min were subjected to aging for 1, 10, and 30 days at 120,170, and 250 °C. The greater thicknesses of IMC layers were obtained for a temperature of 250 °C. With increasing Na content in Zn-Al + Na alloys, the thickness reduced, which correlates to the highest value of activation energy for Zn-Al with 1% Na.
6. Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.
PubMed
Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira
2013-01-14
The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.
7. Reversible transition between coherently strained BiFeO3 and the metastable pseudotetragonal phase on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001)
Fu, Z.; Yin, Z. G.; Zhang, X. W.; Chen, N. F.; Zhao, Y. J.; Bai, Y. M.; Zhao, D. Y.; Zhang, H. F.; Yuan, Y. D.; Chen, Y. N.; Wu, J. L.; You, J. B.
2017-02-01
Coherently strained BiFeO3 epitaxial films deposited on (001)-oriented (LaAlO3)0.3(Sr2AlTaO6)0.7 have a tetragonal crystal form, a stress-distorted version of the rhombohedral phase. A conversion from coherent BiFeO3 to a new, tilted pseudotetragonal phase with the c/a ratio exceeding 1.2 is observed beyond the critical thickness of 60 nm. X-ray reciprocal space maps display that this highly elongated metastable structure is monoclinically distorted by ˜0.2° and exhibits an out-of-plane tilt of ˜3°. These observations are at odds with traditional understandings that a coherent epilayer should turn into its parent structure upon increasing the thickness, providing a new insight into the strain relaxation mechanism of epitaxial films. We show that in the heating and cooling cycles, the transition between these two phases is completely reversible and is associated with the alleviation of thermal stress. Our results reveal that the coherent BiFeO3 epilayer with tetragonal symmetry stabilized by moderate compressive strain behaves as a structural bridge that links the thermally stable rhombohedral phase and the metastable tetragonal-like phase with a giant axial ratio. Moreover, the finding of a BiFeO3 phase mixture in our study extends the threshold in-plane strain of the stress-driven morphotropic phase boundary to a value as low as -2.3%.
8. Structure and properties during aging of an Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049
NASA Technical Reports Server (NTRS)
Gayle, Frank W.; Heubaum, Frank H.; Pickens, Joseph R.
1991-01-01
An Al-Cu-Li-Ag-Mg alloy, Weldalite (trademark) 049, was recently introduced as an ultra-high strength alloy (7000 MPa yield strength in artificially aged tempers) with good weldability. In addition, the alloy exhibits an extraordinary natural aging response (440 MPa yield strength (YS) in the unstretch condition) and a high ductility reversion condition which may be useful as a cold-forming temper. In contrast to other Al-Li alloys, these properties can essentially be obtained with or without a stretch or other coldworking operation prior to aging. Preliminary studies have revealed that the T4 temper (no stretch, natural age) is strengthened by a combination of GP zones and delta prime (Al3Li). The T6 temper (no stretch, aged at 180 C to peak strength) was reported to be strengthened primarily by T(sub 1) phase (Al2CuLi) with a minor presence of a theta prime like (Al2Cu) phase. On the other hand, a similar but lower solute containing alloy was reported to contain omega, (stoichiometry unknown), theta prime, and S prime in the peak strength condition. The purpose of this study is to further elucidate the strengthening phases in Weldalite (trademark) 049 in the unstretched tempers, and to follow the development of the microstructure from the T4 temper through reversion (180 C for 5 to 45 minutes) to the T6 temper.
9. Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys
SciTech Connect
Trishkina, L. Zboykova, N.; Koneva, N. Kozlov, E.; Cherkasova, T.
2016-01-15
The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.
10. Synthesis of Al2O3 nanoparticles highly distributed in YBa2Cu3O7 superconductor by citrate-nitrate auto-combustion reaction
Suan, Mohd Shahadan Mohd; Johan, Mohd Rafie
2013-09-01
The effects of Al2O3 nanoparticles on the structure and superconducting properties of YBa2Cu3O7-δ matrix prepared by auto-combustion reaction were investigated. The auto-combustion reaction has successfully transformed the Al nitrate added YBCO precursor gels to very fine ashes which yielded to Al2O3 and YBCO phases after the calcination process at 900 °C. The resultant reactions produced nanocrystalline YBa2Cu3O7-δ powders having well distributed Al2O3 nanoparticles (∼10 nm). The TG/DTA analysis reveals that the Al nitrate added precursor gels decomposed by two-steps reaction at temperature of 180 and 220 °C due to the decomposition of Al nitrate followed by Y, Ba and Cu nitrates. The XRD pattern showed the orthorhombic structure of Al2O3 added YBa2Cu3O7-δ powders having the particle size ranged in between 20 and 25 nm. SEM analysis showed that Al2O3 nanoparticles were distributed along the grain boundaries of YBa2Cu3O7-δ matrix for the higher mol of Al nitrate. The higher concentration of Al2O3 reacts with the YBa2Cu3O7 matrix to form Al3+ rich spots and diffuse within the YBa2Cu3O7-δ superconducting matrix which was confirmed by EDX analysis. The samples produced in this work were electrically superconducting at temperature above 85 K as measured by using standard four-probe technique. Formation of alumina precipitates and incorporation of Al3+ into YBa2Cu3O7-δ structure was found to significantly reduce the Tc of pure YBa2Cu3O7-δ.
11. The effect of particle size on the electrical conductivity of CuCl (Al2O3) composites
NASA Technical Reports Server (NTRS)
Chang, M. R.-W.; Shahi, K.; Wagner, J. B., Jr.
1984-01-01
The conductivity of CuCl containing Al2O3 of 0.06, 0.3, 1, 3, 8, and 15 micron sized particles was measured between 25 and 390 C. Conductivity was enhanced for the 0.06 and 0.3 sized Al2O3 particles for temperatures below approximately 250 C. The maximum enhancement occurred at 10 m/o of 0.06 micron Al2O3 at 25 C. Uncertain degrees of agglomeration as well as the grain size of the matrix were found to be significant.
12. Al-TiC Composites Fabricated by a Thermally Activated Reaction Process in an Al Melt Using Al-Ti-C-CuO Powder Mixtures: Part II. Microstructure Control and Mechanical Properties
Cho, Young-Hee; Lee, Jung-Moo; Kim, Su-Hyeon
2015-03-01
Controlling the processing parameters is important to minimize such undesirable microstructural features in Al/TiC composites as unreacted C, incomplete reaction products of Al3Ti and TiC aggregates, which originate from the pellet microstructure upon the combustion reaction of an Al-Ti-C-CuO pellet in an Al melt. In particular, the mean particle size of elemental powders is a key factor linked to the formation of TiC aggregates, which is significantly suppressed with smaller initial particles of Ti and C by mixing them homogenously by ball milling. Al-Cu-Mg alloys reinforced with up to 12 vol pct TiC are fabricated by the developed process, followed by extrusion. The composites after heat treatment exhibit high elastic modulus and an ultimate tensile strength of 93 GPa and 461 MPa, respectively, with a low coefficient of thermal expansion of 17.11 ppm/K.
13. Transitions in Wetting Behavior Between Liquid Ag-CuO Alloys and Al2O3Substrates
SciTech Connect
Friant, Jared R.; Meier, Alan; Darsell, Jens T.; Weil, K. Scott; Rohrer, G.
2012-02-24
Reactive air brazing (RAB) is a method for joining ceramics with applications in high temperature technologies such as gas separation and solid oxide fuel cell (SOFC) components. An understanding of wetting behavior is critical for optimization of the brazing process. In the current study, the wetting behavior of Ag-CuO on Al2O3 was evaluated. Based on in-situ contact angle measurements, three regions of wetting behavior were identified in the composition range of 0 to 40 mol% CuO. The first transition, a 20° decrease between 2 mol% CuO and 4 mol% CuO, was attributed to the liquid composition miscibility gap, and the second, a 10° decrease between 10 mol% CuO and 20 mol% CuO, was hypothesized to be dominated by the formation of a reaction product. Small, discontinuous reaction regions were identified via electron probe microanalysis (EPMA) but could not be verified with X-ray photoelectron spectroscopy analysis (XPS).
14. Impact of CrSiTi and NiSi on the Thermodynamics, Microstructure, and Properties of AlCoCuFe-Based High-Entropy Alloys
Wang, Xiao-Rong; Wang, Zhao-Qin; Lin, Tie-Song; He, Peng; Sekulic, Dusan P.
2016-05-01
Aiming to solve the problem of spontaneous combustion on titanium via electrospark deposition (ESD), two AlCoCuFe-based high-entropy alloys (HEAs), AlCoCuFe- x ( x = CrSiTi, NiSi), were produced by vacuum arc melting as electrodes in ESD process. The thermodynamic analysis of AlCoCuFe-based HEAs were carried out using the concept of mixing enthalpy matrix and a powerful thermodynamic calculation toolbox (HEA-Thermo-Calcu). The microstructure and mechanical properties of the two alloys were investigated. The AlCoCuFeCrSiTi alloy contains a body-centered cubic (BCC) phase and a face-centered cubic (FCC) phase. The AlCoCuFeNiSi alloy is composed of two BCC phases and an FCC phase. Addition of CrSiTi and NiSi to AlCoCuFe-based alloys makes the enthalpy of mixing to be sizably more negative than for the other AlCoCuFe-based HEAs. Notwithstanding the fact that the thermodynamic parameters do not agree with Yang's proposition, the two alloys form simple solid solutions. The electronegativity difference (Δ χ) favors a formation of the solid solution when Δχ ≤ 14.2. The hardness of AlCoCuFe- x ( x = CrSiTi, NiSi) alloys reaches 935 HV and 688 HV, respectively. The yield strength, fracture strength, and ultimate strain of AlCoCuFeNiSi are larger, i.e., 29, 30, and 45%, respectively, than those of the AlCoCuFeCrSiTi alloy.
15. The influence of the X atoms and Al 3p occupied states in AlTiX2(X=Fe,Cu,Co,Ni) intermetallics
Fu, Hongzhi; Chen, Dong; Cheng, Xinlu; Gao, Tao; Yang, Xiangdong
2007-01-01
The electronic structures of the ternary (Heusler) L21-phase compounds AlTiX2(X=Fe,Cu,Co,Ni) are calculated by first-principles using full potential linearized augmented plane wave (FLAPW) method with the generalized gradient approximation (GGA). The ab initio results are analyzed with a simplified model for Al-based compounds containing transition metal (TM) atoms. The results show that the total density of state (DOS) depends strongly on the positions of TM atoms, and the TM d DOS not only connects with the pseudo-gap which is the indication of the stability of the intermetallic ternary Hume-Rothery (H-R) alloys, but also plays a crucial role in hybridization with other element valence electrons. However, the Al 3s states are repelled far away from the Fermi energy in all studied samples, and the Al 3d states are far more extended-like in the character than the d states. Furthermore, the total DOSs in all the studied samples are modulated by Al 3p states and the Al 3p states are more sensitive than d states to change in the electronic interactions. Then, the Al 3p is also responsible for the major part of the H-R stability of the intermetallic compounds which we have concerned with here. Indeed, the DOSs of the studied alloys show a pseudo-gap near the Fermi level, commonly attributed to the H-R phenomenon. Especially, the AlCu2Ti has more particular flat total DOS than the other AlTiX2 alloys (X=Fe,Co,Ni), which shows the so-called half-metallic behavior or poor metallic character.
16. Size-dependent catalytic performance of CuO on γ-Al2O3: NO reduction versus NH3 oxidation
SciTech Connect
Kwak, Ja Hun; Tonkyn, Russell G.; Tran, Diana N.; Mei, Donghai; Cho, Sung June; Kovarik, Libor; Lee, Jong H.; Peden, Charles HF; Szanyi, Janos
2012-05-25
Catalytic reaction pathways of NH{sub 3} on CuO/{gamma}-Al{sub 2}O{sub 3} catalysts during NH{sub 3} SCR reactions were investigated under oxygen-rich conditions. On 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3}, NH{sub 3} reacted with oxygen to produce NO{sub x}. In contrast, on the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} catalyst NH{sub 3} reacted primarily with NO to form N{sub 2} with conversion efficiency of {approx}80% at 450 C. H{sub 2}-TPR results show that Cu species present in 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3} can be easily reduced at {approx}160 C, which suggests the formation of large CuO clusters on the alumina surface. On the other hand, the TPR spectrum obtained from the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} catalyst does not show any measurable H{sub 2} consumption up to 700 C, which suggests the presence of non-reducible isolated Cu species in this catalyst. STEM images collected from 10 wt % CuO/{gamma}-Al{sub 2}O{sub 3} show nano-sized CuO clusters, while no evidence of cluster formation is seen in the images recorded from the 0.5 wt % CuO/{gamma}-Al{sub 2}O{sub 3} sample, due to the intrinsic limitation of low Z contrast between highly dispersed Cu (atomic weight = 63.5) species and the alumina support (atomic weight of Al = 27). EXAFS data indicates the presence of Cu-Cu (Al) second shell at 0.35 nm only in the 10% CuO/{gamma}-Al{sub 2}O{sub 3} catalyst, and an estimated coordination number of {approx}1.7. The XANES and EXAFS results suggest the formation of relatively highly dispersed Cu oxide nanoclusters even at 10 wt % Cu loading. However, FT-IR spectra collected after CO adsorption on the CuO/{gamma}-Al{sub 2}O{sub 3} catalysts demonstrate the existence of different Cu species at Cu loadings of 0.5 and 10 wt %. Density functional theory (DFT) results show that supported CuO clusters, represented by a two-dimensional (2D) CuO monolayer, can effectively dissociate adsorbed NO and O2 to produce atomic oxygen species. These reactive atomic oxygen
17. Characterization of Cold Sprayed CuCrAl-Coated and Uncoated GRCop-84 Substrates for Space Launch Vehicles
NASA Technical Reports Server (NTRS)
Raj, S. V.; Karthikeyan, J.; Lerch, B. A.; Barrett, C.; Garlich, R.
2007-01-01
A newly developed Cu-23(wt.%)Cr-5%Al (CuCrAl) alloy is currently being considered as a protective coating for GRCop-84 (Cu-8(at.%)Cr-4%Nb). The coating was deposited on GRCop-84 substrates by the cold spray deposition technique. Cyclic oxidation tests conducted in air on both coated and uncoated substrates between 773 and 1073 K revealed that the coating remained intact and protected the substrate up to 1073 K. No significant weight loss of the coated specimens were observed at 773 and 873 K even after a cumulative cyclic time of 500 h. In contrast, the uncoated substrate lost as much as 80% of its original weight under similar test conditions. Low cycle fatigue tests revealed that the fatigue lives of thinly coated GRCop-84 specimens were similar to the uncoated specimens within the limits of experimental scatter. It is concluded that the cold sprayed CuCrAl coating is suitable for protecting GRCop-84 substrates.
18. Pool boiling of water-Al2O3 and water-Cu nanofluids on horizontal smooth tubes
PubMed Central
2011-01-01
Experimental investigation of heat transfer during pool boiling of two nanofluids, i.e., water-Al2O3 and water-Cu has been carried out. Nanoparticles were tested at the concentration of 0.01%, 0.1%, and 1% by weight. The horizontal smooth copper and stainless steel tubes having 10 mm OD and 0.6 mm wall thickness formed test heater. The experiments have been performed to establish the influence of nanofluids concentration as well as tube surface material on heat transfer characteristics at atmospheric pressure. The results indicate that independent of concentration nanoparticle material (Al2O3 and Cu) has almost no influence on heat transfer coefficient while boiling of water-Al2O3 or water-Cu nanofluids on smooth copper tube. It seems that heater material did not affect the boiling heat transfer in 0.1 wt.% water-Cu nanofluid, nevertheless independent of concentration, distinctly higher heat transfer coefficient was recorded for stainless steel tube than for copper tube for the same heat flux density. PMID:21711741
19. A comparative first-principles study on electronic structures and mechanical properties of ternary intermetallic compounds Al8Cr4Y and Al8Cu4Y: Pressure and tension effects
Yang, Wenchao; Pang, Mingjun; Tan, Yong; Zhan, Yongzhong
2016-11-01
An investigation into the bulk properties, elastic properties and Debye temperature under pressure, and deformation mode under tension of Al8Cu4Y and Al8Cr4Y compounds was investigated by using first principles calculations based on density functional theory. The calculated lattice constants for the ternary compounds (Al8Cu4Y and Al8Cr4Y) are in good agreement with the experimental data. It can be seen from interatomic distances that the bonding between Al1 atom and Cr, Y, and Al2 atoms in Al8Cr4Y are stronger than Al8Cu4Y. The results of cohesive energy show that Al8Cr4Y should be easier to be formed and much stronger chemical bonds than Al8Cu4Y. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν can be obtained by using the Voigt-Reuss-Hill averaging scheme. From the results of elastic properties, Al8Cr4Y has the stronger mechanical behavior than Al8Cu4Y. Our calculations also show that pressure has a greater effect on mechanical behavior for both compounds. The ideal tensile strength are obtained by stress-strain relationships under [001](001) uniaxial tensile deformation, which are 15.4 and 23.4 GPa for Al8Cu4Y and Al8Cr4Y, respectively. The total and partial density of states and electron charge density under uniaxial tensile deformations for Al8Cu4Y and Al8Cr4Y compounds are also calculated and discussed in this work.
20. Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size
PubMed Central
Liu, Rui; Tian, Yanzhong; Zhang, Zhenjun; An, Xianghai; Zhang, Peng; Zhang, Zhefeng
2016-01-01
It is commonly proposed that the fatigue strength can be enhanced by increasing the tensile strength, but this conclusion needs to be reconsidered according to our study. Here a recrystallized α-Cu-15at.%Al alloy with moderate grain size of 0.62 μm was fabricated by cold rolling and annealing, and this alloy achieved exceptional high fatigue strength of 280 MPa at 107 cycles. This value is much higher than the fatigue strength of 200 MPa for the nano-crystalline counterpart (0.04 μm in grain size) despite its higher tensile strength. The remarkable improvement of fatigue strength should be mainly attributed to the microstructure optimization, which helps achieve the reduction of initial damage and the dispersion of accumulated damage. A new strategy of “damage reduction” was then proposed for fatigue strength improvement, to supplement the former strengthening principle. The methods and strategies summarized in this work offer a general pathway for further improvement of fatigue strength, in order to ensure the long-term safety of structural materials. PMID:27264347
1. Effect of cold compression on precipitation and conductivity of an Al-Li-Cu alloy.
PubMed
Khan, A K; Robinson, J S
2008-12-01
Transmission electron microscopy has been used to investigate the effect of increasing the degree of deformation applied by cold compression on the ageing kinetics and electrical conductivity response of an Al-Li-Cu alloy containing Mg and Ag. When cold compressed greater than 3%, the increased dislocation density accelerates the widespread precipitation of the T(1) phase resulting in an enhanced age hardening response. The lengthening rate of T(1) precipitates is also reduced in this cold compressed condition owing to the reduced local solute supersaturation, a result of the widespread precipitation of T(1) plates. Cold compression by less than 3% does not increase the age hardening response, and the precipitation of GP zones/theta'' appears to be suppressed. Precipitation of the T(1) phase is also not significantly enhanced compared with that of the more than 3% cold compressed conditions. The anomalous decrease in electrical conductivity is associated with the nucleation and growth of the T(1) phase. Strain fields around T(1) precipitates combined with the increased volume fraction of T(1) are thought to be the cause of the anomalous conductivity behaviour.
2. Shock melting method to determine melting curve by molecular dynamics: Cu, Pd, and Al
SciTech Connect
Liu, Zhong-Li; Zhang, Xiu-Lu; Cai, Ling-Cang
2015-09-21
A melting simulation method, the shock melting (SM) method, is proposed and proved to be able to determine the melting curves of materials accurately and efficiently. The SM method, which is based on the multi-scale shock technique, determines melting curves by preheating and/or prepressurizing materials before shock. This strategy was extensively verified using both classical and ab initio molecular dynamics (MD). First, the SM method yielded the same satisfactory melting curve of Cu with only 360 atoms using classical MD, compared to the results from the Z-method and the two-phase coexistence method. Then, it also produced a satisfactory melting curve of Pd with only 756 atoms. Finally, the SM method combined with ab initio MD cheaply achieved a good melting curve of Al with only 180 atoms, which agrees well with the experimental data and the calculated results from other methods. It turned out that the SM method is an alternative efficient method for calculating the melting curves of materials.
3. A facile electron microscopy method for measuring precipitate volume fractions in AlCuMg alloys
SciTech Connect
Zhao, X.Q.; Shi, M.J.; Chen, J.H. Wang, S.B.; Liu, C.H.; Wu, C.L.
2012-07-15
Precipitate volume fraction is an important parameter to estimate the strength of precipitation-hardened metals. In this study, a facile method was applied to measure the precipitate volume fractions in an age-hardened AlCuMg alloy. In this method, the precipitate volume fraction values can be obtained by multiplying the volume precipitate number densities with the averaged precipitate volumes, which can be easily measured in scanning electron microscopy and transmission electron microscopy, respectively. Compared with the conventional method, in which the specimen thickness has to be measured in transmission electron microscopy, the method proposed in this study is more facile to perform. - Highlights: Black-Right-Pointing-Pointer We have proposed a facile method to measure precipitate volume fractions for precipitation-hardened metals. Black-Right-Pointing-Pointer This technique works well for the square-shaped {theta} Prime -phase nano-precipitates in 2xxx aluminum alloys. Black-Right-Pointing-Pointer Interesting is that the proposed method is easy for materials scientists and engineers to perform.
4. Softening Behavior of a New Al-Zn-Mg-Cu Alloy Due to TIG Welding
Zhang, Liang; Li, Xiaoyan; Nie, Zuoren; Huang, Hui; Sun, Jiantong
2016-05-01
A new Al-Zn-Mg-Cu alloy with T6 temper was welded by TIG welding, and the softening behavior of the joint was evaluated. Results show that the ultimate tensile strength of the joint is 436.2 ± 26.4 MPa which is about 64.5% of that of the base metal (BM). Fusion zone (FZ) is the weakest region even though its microhardness increases from 107.6 to 131.3 HV within 90 days after welding. Microhardness of the heat-affected zone (HAZ) adjacent to FZ increases from 125.2 to 162.3 HV within 90 days. However, a valley value of microhardness appears in the rest of the HAZ that increases from 112.1 to 128.1 HV within 90 days. The variation of grain size and precipitates is regarded as the main cause of softening in both FZ and HAZ. The grain size of FZ is about 33.9 μm, whereas 8.7 and 8.4 μm for HAZ and BM, respectively. A large number of η' phases distribute dispersively in BM, whereas precipitates in FZ identified as GPI zones are finer and fewer. Besides, precipitates in HAZ adjacent to FZ are also GPI zones. Precipitates in HAZ far away from FZ are coarser and fewer than those in BM and η phases begin to emerge.
5. Identification of strengthening phases in Al-Cu-Li alloy Weldalite 049
NASA Technical Reports Server (NTRS)
Langan, T. J.; Pickens, J. R.
1989-01-01
The tensile properties in the peak-strength T8 temper for Weldalite 049, a family of ultrahigh-strength weldable Al-Cu-Li-based alloys with a Li content ranging from 0 to 1.9 wt percent, are investigated, and strengthening precipitates at selected Li levels are identified. Relatively small amounts of Ag and Mg were found to be extremely effective in stimulating precipitation in Weldalite 049, resulting in a homogeneous distribution of fine, platelike precipitates with a 111-type habit plane in the peak-aged, T8 temper. The yield and tensile strengths are strongly dependent on Li content, with a peak in the range of 1.1 to 1.4 wt percent Li. At above 1.4 wt percent Li, strength decreases rapidly, which is associated with delta-prime precipitation. For high-resolution TEM, the structure of T(1)-type precipitates in Weldalite 049 is similar to that of T(1) platelets in 2090.
6. Phase transformations in the system Cu-Zn-Al under conditions far from equilibrium
Klopotov, Anatolii; Ivanov, Yuri; Vlasov, Viktor; Dedov, Nikolai; Loskutov, Oleg
2016-01-01
It is shown that the alloy Cu-Zn-Al is a multiphase material. Under equilibrium conditions this alloy can form an α-phase (FCC crystalline lattice) and a β-phase (simple cubic crystalline lattice) based on copper. The possibility of formation of a γ-phase due to a three-component alloy composition is revealed. It is established that different chemical composition of the copper-based solid solution (alloys with zinc or alloys with aluminum), different concentration of the second element in a solid solution leads to the fact that within the same type of the crystalline lattice there is a certain amount of α- and γ-phases, differing in the parameter value of the crystalline lattice. The possibility of formation of powder alloys with an x-ray amorphous and a nanocrystalline structure using the plasma chemical synthesis methods is demonstrated. A wide variety of binary phases, each with different concentrations of zinc and aluminum in a solid copper-based solution is revealed. These results indicate that plasma-chemical synthesis of metal alloy powders is accompanied by separation of elements. Powders of the ternary composition are not detected.
7. Precipitation under cyclic strain in solution-treated Al4wt%Cu I: mechanical behavior
SciTech Connect
2008-01-01
Solution-treated AL-4wt%Cu was strain-cycled at ambient temperature and above, and the precipitation and deformation behaviors investigated by TEM. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy super-saturation generated by cyclic strain and the presence of a continually refreshed dislocation density to provide heterogeneous nucleation sites. Texture effects as characterized by Orientation Imaging Microscopy appear to be responsible for latent hardening in specimens tested at room temperature, with increasing temperatures leading to a gradual hardening throughout life due to precipitation. Specimens exhibiting rapid precipitation hardening appear to show a greater effect of texture due to the increased stress required to cut precipitates in specimens machined from rolled plate at an angle corresponding to a lower average Schmid factor. The accelerated formation of grain boundary precipitates appears to be partially responsible for rapid inter-granular fatigue failure at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.
8. Formation of porous inner architecture at the interface of magnetic pulse welded Al/Cu joints
Sapanathan, T.; Raoelison, R. N.; Yang, K.; Buiron, N.; Rachik, M.
2016-10-01
Porous inner architecture has been revealed at the interface of magnetic pulse welded aluminum/copper (Al/Cu) joints. These materials could serve the purpose of heterogeneous architectured materials, while their makeup of inner architecture of porous interface with the pore sizes of sub-micron to a few microns, could offer potential attributes in energy storage application. Two welding cases with various impact intensities are compared. An input voltage of 6.5 kV with an initial air gap of 1.5 mm and a higher voltage of 7.5 kV with a large initial air gap of 5 mm are respectively considered as two cases with low and high velocity impacts. Overall morphology of the porous medium was revealed at the interface either in layered or pocketed structures. The allocation of the porous zone and pore sizes vary with the impact condition. The low velocity impact welding conditions also produces smaller pores compared to the high velocity impact case, where the pore sizes varies in submicron to a few microns (<10μm). By investigating the potential mechanism of the porous zone formation, it was identified that a combined phenomena of cavitation and coalescence play a major role in nucleation and growth of the pores where a rapid cooling that eventually freezes the porous structure at the interface.
9. Enriched alloy layer on an Al-Cu alloy studied by cyclic voltammetry
García Vergara, S. J.; Blanco Pinzon, C. E.; Skeldon, P.
2017-01-01
The behaviour of enriched Al-0.7at.%Cu alloy is investigated using cyclic voltammetry. Enriched alloy layers at the interface between the alloy/oxide film were developed by alkaline etching at 5mAcm-2 in 0.1M sodium hydroxide solution at 298K, with the time of etching determining the extent of enrichment. Cyclic voltammograms were recorded at a scan rate of 10mV s-1 in naturally aerated 0.1M ammonium pentaborate solution at 298K. The current overshoot of the enriched alloys was different from that for non-enriched alloy. The latter material revealed the usual single peaks, which are very similar. In contrast, the overshoot comprised two or more components for the enriched alloys. The behaviour is suggested to be associated with the atomic bonding of aluminium in copper-rich and aluminium-rich regions of the enriched alloy layer, with influence on the activation potentials for oxidation of aluminium.
10. Aging kinetics of a silicon carbide reinforced Al-Zn-Mg-Cu alloy
SciTech Connect
Davies, C.H.J.; Raghunathan, N.; Sheppard, T.
1994-01-01
The aging kinetics of a composite of an Al-Zn-Mg-Cu powder (CW67) combined with a varied volume fraction of a particulate silicon carbide were investigated by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). DSC revealed that the maximum rate of precipitation of the metastable {eta}{prime} phase was substantially lower for CW67/SiC/20p than for the unreinforced alloy or CW67/SiC/10p. TEM of isothermally aged material revealed differences between the unreinforced alloy and composites in respect of precipitate size and morphology. The authors conclude that SiC additions, by dint of additional dislocations generated during quenching, can affect the aging of CW67 either by accelerating the nucleation of precipitates or by accelerating precipitate growth. The aging rate of CW67/SiC/20p was increased by accelerating both the nucleation of precipitates and growth, whereas the aging in CW67/SiC10p was enhanced by accelerating precipitate growth only.
11. Precipitation in solution-treated Al-4wt%Cu under cyclic strain
SciTech Connect
2010-09-15
Solution-treated Al-4wt%Cu was strain-cycled at ambient temperature and above and the precipitation behavior investigated by TEM. In the temperature range 100 C to 200 C precipitation of {Theta}'' appears to have been suppressed and precipitation of {Theta}' promoted via cyclic strain. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy supersaturation generated by dislocation motion, with a diminishing effect observed at higher temperatures due to the faster recovery of non-equilibrium vacancy concentrations. {Theta}' precipitates generated under cyclic strain are considerably smaller and more finely dispersed than those typically produced via quench-aging due to their heterogeneous nucleation on dislocations, and possess a low aspect ratio and rounded edges of the broad faces due to the introduction of ledges into the growing precipitates by dislocation cutting. Frequency effects indicate that dislocation motion, rather than the extremely small precipitate size, is responsible for the observed reduction in aspect ratio. Accelerated formation of grain boundary precipitates appears partially responsible for rapid intergranular fatigue failure following cycling at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.
12. Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size
Liu, Rui; Tian, Yanzhong; Zhang, Zhenjun; An, Xianghai; Zhang, Peng; Zhang, Zhefeng
2016-06-01
It is commonly proposed that the fatigue strength can be enhanced by increasing the tensile strength, but this conclusion needs to be reconsidered according to our study. Here a recrystallized α-Cu-15at.%Al alloy with moderate grain size of 0.62 μm was fabricated by cold rolling and annealing, and this alloy achieved exceptional high fatigue strength of 280 MPa at 107 cycles. This value is much higher than the fatigue strength of 200 MPa for the nano-crystalline counterpart (0.04 μm in grain size) despite its higher tensile strength. The remarkable improvement of fatigue strength should be mainly attributed to the microstructure optimization, which helps achieve the reduction of initial damage and the dispersion of accumulated damage. A new strategy of “damage reduction” was then proposed for fatigue strength improvement, to supplement the former strengthening principle. The methods and strategies summarized in this work offer a general pathway for further improvement of fatigue strength, in order to ensure the long-term safety of structural materials.
13. Barrier/Cu contact resistivity
SciTech Connect
Reid, J.S.; Nicolet, M.A.; Angyal, M.S.; Lilienfeld, D.; Shacham-Diamand, Y.; Smith, P.M.
1995-10-17
The specific contact resistivity of Cu with ({alpha} + {beta})-Ta, TiN, {alpha}-W, and amorphous-Ta{sub 36}Si{sub 14}N{sub 50} barrier films is measured using a novel four-point-probe approach. Geometrically, the test structures consist of colinear sets of W-plugs to act as current and voltage probes that contact the bottom of a planar Cu/barrier/Cu stack. Underlying Al interconnects link the plugs to the current source and voltmeter. The center-to-center distance of the probes ranges from 3 to 200 {micro}m. Using a relation developed by Vu et al., a contact resistivity of roughly 7 {times} 10{sup {minus}9} {Omega} cm{sup 2} is obtained for all tested barrier/Cu combinations. By reflective-mode small-angle X-ray scattering, the similarity in contact resistivity among the barrier films may be related to interfacial impurities absorbed from the deposition process.
14. First-principles investigation of structural and magnetic disorder in CuNiMnAl and CuNiMnSn Heusler alloys
Aron-Dine, S.; Pomrehn, G. S.; Pribram-Jones, A.; Laws, K. J.; Bassman, L.
2017-01-01
Two quaternary Heusler alloys, equiatomic CuNiMnAl and CuNiMnSn, are studied using density functional theory to understand their tendency for atomic disorder on the lattice and the magnetic effects of disorder. Disordered structures with antisite defects of atoms of the same and different sublattices are considered, with the level of atomic disorder ranging from 3% to 25%. Formation energies and magnetic moments are calculated relative to the ordered ground state and combined with a simple thermodynamical model to estimate temperature effects. We predict the relative levels of disordering in the two equiatomic alloys with good correlation to experimental x-ray diffraction results. The effect of swaps involving Mn is also discussed.
15. Transient Liquid Phase Diffusion Bonding of 6061Al-15 wt.% SiC p Composite Using Mixed Cu-Ag Powder Interlayer
Roy, Pallab; Pal, Tapan Kumar; Maity, Joydeep
2016-08-01
Microstructure and shear strength of transient liquid phase diffusion bonded (560 °C, 0.2 MPa) 6061Al-15 wt.% SiCp extruded composite using a 50-µm-thick mixed Cu-Ag powder interlayer have been investigated. During isothermal solidification that took 2 h for completion, a ternary liquid phase formed due to diffusion of Cu and Ag in Al. Subsequent cooling formed a ternary phase mixture (α-Al + CuAl2 + Ag2Al) upon eutectic solidification. With mixed Cu-Ag powder interlayer, isothermal solidification was faster than for pure Al joints made using a 50-µm-thick Cu foil interlayer and for the composite joints made using a 50-µm-thick Cu foil/powder interlayer under similar conditions. The presence of brittle eutectic phase mixture (CuAl2 + Ag2Al) led to poor joint strength at short TLP bonding times. The mixture disappeared upon isothermal solidification with a 2-h hold yielding improved joint strength even with solidification shrinkage in the joint. Increased holding time (6 h) erased shrinkage via solid state diffusion and yielded the highest joint strength (87 MPa) and fair joint efficiency (83%).
16. Formation and Stability of Equiatomic and Nonequiatomic Nanocrystalline CuNiCoZnAlTi High-Entropy Alloys by Mechanical Alloying
Varalakshmi, S.; Kamaraj, M.; Murty, B. S.
2010-10-01
Nanocrystalline equiatomic high-entropy alloys (HEAs) have been synthesized by mechanical alloying in the Cu-Ni-Co-Zn-Al-Ti system from the binary CuNi alloy to the hexanary CuNiCoZnAlTi alloy. An attempt also has been made to find the influence of nonequiatomic compositions on the HEA formation by varying the Cu content up to 50 at. pct (Cu x NiCoZnAlTi; x = 0, 8.33, 33.33, 49.98 at. pct). The phase formation and stability of mechanically alloyed powder at an elevated temperature (1073 K [800 °C] for 1 hour) were studied. The nanocrystalline equiatomic Cu-Ni-Co-Zn-Al-Ti alloys have a face-centered cubic (fcc) structure up to quinary compositions and have a body-centered cubic (bcc) structure in a hexanary alloy. In nonequiatomic alloys, bcc is the dominating phase in the alloys containing 0 and 8.33 at. pct of Cu, and the fcc phase was observed in alloys with 33.33 and 49.98 at. pct of Cu. The Vicker’s bulk hardness and compressive strength of the equiatomic nanocrystalline hexanary CuNiCoZnAlTi HEA after hot isostatic pressing is 8.79 GPa, and the compressive strength is 2.76 GPa. The hardness of these HEAs is higher than most commercial hard facing alloys ( e.g., Stellite, which is 4.94 GPa).
17. Microstructure evolution of eutectic Al-Cu strips by high-speed twin-roll strip casting process
2015-10-01
In the present investigation, microstructural evolutions of functionally graded eutectic Al-Cu strips prepared by high-speed twin-roll strip caster at different casting speeds and liquid melt superheats were studied. The as-cast sample was subjected to scanning electron microscope to study the evolution of microstructure of the strip at different casting speeds and liquid melt superheats. At different casting speeds, non-equilibrium eutectic structure observed on the Al-Cu eutectic strip consists of lamellar as well as wavy structure with a distinct boundary. The lamellar microstructure consists of alternating layers of well-bonded α-Al phase and θ-Al2Cu phase. The globular flowery structure within the eutectic matrix was observed on the strip at different liquid melt superheats. The microhardness of the as-cast strip was studied by Vickers hardness tester, and it was found that hardness value increases with increasing casting speed and decreases with increasing liquid melt superheat.
18. Isothermal ageing at low temperatures of a smart material: A Cu-Zn-Al-Co shape memory alloy
SciTech Connect
Guilemany, J.M.; Fernandez, J. . Metalurgia Fisica-Ciencia de Materiales)
1994-10-01
Shape memory properties are found in alloys having a martensitic or [beta] structure. These structures are unstable at high and also at low aging temperatures transforming into the eutectoid phases by diffusion controlled processes. The presence of cobalt in heat-treated aluminum bronze was found to cause changes in the proportions of the equilibrium phases, increasing the [alpha] content and decreasing the fraction of the eutectoid [alpha] and [gamma]. On aging the cobalt containing alloy, thee were no structural changes until the temperature was below 350 C. At higher temperatures the martensite decomposed by two different modes. In the first mode, [alpha] phase precipitates at the grain boundaries or around CoAl(Cu) particles and the [gamma] phase is formed afterwards. The second mode of decomposition took place by a transitional [gamma][double prime] precipitation, which takes Al from the matrix, so allowing it to transform to the [gamma] phase. Little work has been carried out on systems such as Cu-Zn-Al-X, where X is a grain refining element. Authors have extensively studied the improvements of the properties of a Cu-Zn-Al-Co shape memory alloy. Calorimetric methods have also been used by the present authors to study the decomposition phenomena of this alloy. The present work is a continuation of that study to determine the hardness and structural changes brought about by the addition of Co.
19. Comparative analysis of the effects of tantalum doping and annealing on atomic layer deposited (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} as potential gate dielectrics for GaN/Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistors
SciTech Connect
Partida-Manzanera, T.; Roberts, J. W.; Sedghi, N.; Potter, R. J.; Bhat, T. N.; Zhang, Z.; Tan, H. R.; Dolmanan, S. B.; Tripathy, S.
2016-01-14
This paper describes a method to optimally combine wide band gap Al{sub 2}O{sub 3} with high dielectric constant (high-κ) Ta{sub 2}O{sub 5} for gate dielectric applications. (Ta{sub 2}O{sub 5}){sub x}(Al{sub 2}O{sub 3}){sub 1−x} thin films deposited by thermal atomic layer deposition (ALD) on GaN-capped Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor (HEMT) structures have been studied as a function of the Ta{sub 2}O{sub 5} molar fraction. X-ray photoelectron spectroscopy shows that the bandgap of the oxide films linearly decreases from 6.5 eV for pure Al{sub 2}O{sub 3} to 4.6 eV for pure Ta{sub 2}O{sub 5}. The dielectric constant calculated from capacitance-voltage measurements also increases linearly from 7.8 for Al{sub 2}O{sub 3} up to 25.6 for Ta{sub 2}O{sub 5}. The effect of post-deposition annealing in N{sub 2} at 600 °C on the interfacial properties of undoped Al{sub 2}O{sub 3} and Ta-doped (Ta{sub 2}O{sub 5}){sub 0.12}(Al{sub 2}O{sub 3}){sub 0.88} films grown on GaN-HEMTs has been investigated. These conditions are analogous to the conditions used for source/drain contact formation in gate-first HEMT technology. A reduction of the Ga-O to Ga-N bond ratios at the oxide/HEMT interfaces is observed after annealing, which is attributed to a reduction of interstitial oxygen-related defects. As a result, the conduction band offsets (CBOs) of the Al{sub 2}O{sub 3}/GaN-HEMT and (Ta{sub 2}O{sub 5}){sub 0.16}(Al{sub 2}O{sub 3}){sub 0.84}/GaN-HEMT samples increased by ∼1.1 eV to 2.8 eV and 2.6 eV, respectively, which is advantageous for n-type HEMTs. The results demonstrate that ALD of Ta-doped Al{sub 2}O{sub 3} can be used to control the properties of the gate dielectric, allowing the κ-value to be increased, while still maintaining a sufficient CBO to the GaN-HEMT structure for low leakage currents.
20. Influence of nitrogen-doping concentration on the electronic structure of CuAlO2 by first-principles studies
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# Impacts of an indigenous settlement on the taxonomic and functional structure of dung beetle communities in the Venezuelan Amazon
## Abstract
In the last 50 years, traditionally nomadic indigenous communities in Amazonia have increasingly adopted more sedentary lifestyles as a result of external influences. Permanent settlements lead to the concentration of disturbances (e.g., forest extraction and hunting) and threaten vulnerable species as well as those that provide important ecosystem services such as dung beetles. Here we evaluated the abundance, taxonomic, and functional structure (composition and diversity) of an ecological indicator group—dung beetles—along a disturbance gradient associated with a permanent settlement of the Jotï people in the Amazonian region of Venezuela. We applied generalized linear model to assess the response of dung beetle abundance to settlement distance and latent variable model to assess the influence of settlement distance on taxonomic diversity and functional structure. We found the abundance of roller-species increased but small-bodied beetles decreased away from the settlement. We found that proximity to the Jotï settlement did not affect metrics of taxonomic and functional diversity of the dung beetle assemblages in general, although functional evenness was lower away from the settlement. In contrast, we found impacts on the functional composition of dung beetles, with significant increase in the community-weighted means for roller species and large-bodied dung beetles away from Jotï settlement. Our findings suggest that the transition from nomadism to a more sedentary lifestyle has not caused widespread collapse in the diversity of dung beetle assemblages surrounding the settlement, however significant trends were observed in species-specific responses to human impact, and these responses were mediated by functional traits.
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## Acknowledgements
We thank the Jotï people for their contribution and collaboration on this study and their kind hospitality during our stay with them. We are also grateful to our colleagues at Laboratorio Ecología Humana de IVIC for logistical support. We thank Cong Liu and Nicholas Friedman for their input, Kenneth Dudley for his help with Figure 1, and two anonymous reviewers for their comments on the manuscript. Funding for this research was provided by the Charles H. and Anne Morrow Lindbergh Foundation and the American Philosophical Society. J.C. and E.P.E. were supported by subsidy funding to the Okinawa Institute of Science and Technology.
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### Corresponding author
Correspondence to Juanita Choo.
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Communicated by David L Hawksworth.
## Appendices
### Justification for the use of negative binomial GLMM
The reasons for using the negative binomial distribution and a GLMM in our analyses are as follows. Initial analysis using a Poisson GLMM resulted in overdispersion due to the relatively large number of zeros in the beetle abundance (60%). Zero inflated Poisson models (Zuur and Ieno 2016b) were also overdispersed and we therefore applied the negative binomial GLMM.
Model equation for negative binomial GLMM
$$Beetles_{ij} \sim NB\left( {\mu_{ij} ,\theta } \right)$$
$$E\left( {Beetles_{ij} } \right) = \mu_{ij}$$
$$\mu_{ij} = e^{{Intercept + Covariates_{ij}+a_{i}+ s_{j}}}$$
$$a_{i} \sim N\left( {0,\sigma_{Trap}^{2}}\right)$$
$$s_{j} \sim N\left( {0,\sigma_{Species}^{2}}\right)$$
Beetlesij is the number of beetles caught in trap i for species j, where i = 1,.., 55 and j = 1,..,26. To allow for dependency between multiple observations from the same trap, we included a random intercept site (ai), which is assumed to be normal and independently distributed with mean 0 and variance σ2Trap. We also included a random intercept species (bj), which is assumed to be normal and independently distributed with mean 0 and variance σ2Species. This random effect imposes a dependency structure between observed beetle numbers from the same species (i.e. observations from different traps from the same species).
### Model fitting using Bayesian context using Markov Chain Monte Carlo (MCMC) implemented in JAGS
Models were fit in a Bayesian context using Markov Chain Monte Carlo (MCMC) techniques implemented in JAGS (Plummer 2003) from within R (further details in Appendix 1). A burn-in of 80,000 iterations was used with 3 chains. We used a thinning rate of 100 and 4500 iterations were used for each posterior distribution. All continuous covariates were standardized. Once the models were fitted, model validation was applied to investigate the presence of any residual patterns. We plotted posterior mean Pearson residuals versus posterior mean fitted values, versus each covariate, and we also inspected the posterior mean residuals for any spatial dependency, and dependency between species.
The specification controlling the MCMC sampling for the LVM model uses the default values in the ‘boral’ package and are as follows:
1. 1.
Length of burn-in i.e., the number of iterations to discard at the beginning of the MCMC sampler was 1000.
2. 2.
Number of iterations including burn-in was 40,000.
3. 3.
Thinning rate was 30.
4. 4.
Seed for JAGS sampler was set to the value 123.
### Formulation of the latent variable model
The formulation of the LVM is as follows:
$$Y_{ij} \sim N\left( {\mu_{ij} ,\sigma_{j}^{2} } \right)$$
$$E\left( {Y_{ij} } \right) = \mu_{ij} = \alpha_{j} + X_{j} \times \beta_{j} + u_{ij}$$
The Yij is the value of the ith observation on diversity or functional structure index j. There are 9 response variables, hence j = 1, …, 9. And there are 55 sites, which means that i = 1, …, 55. The xj contains the 5 covariates. In an ordinary linear regression model, we assume that the residual terms uij are independent and normally distributed. In a multivariate GLMM we use a non-diagonal residual covariance matrix to model dependency between response variables. In the LVM we use the following construction.
$$u_{ij} = Z_{i}^{'} \times \lambda_{j}$$
The residuals uij are equal to a linear combination of typically 2 latent variables zi (each of length 55), very much like axes in ordination techniques (e.g. principal component analysis, canonical correspondence analysis). The λjs are factor loadings and tell us how the latent axes influence the response variables. Model validation followed the steps described in Hui et al. (2015). A more detailed description of LVM models can be found in Warton et al. (2015). We compared LVMs with 0, 1 and 2 latent axes using the widely applicable information criterion (WAIC), the expected Akaike information criterion (EAIC) and the expected Bayesian information criterion (BIC). See the ‘boral’ package documentation for or original references (Akaike 1974; Schwarz 1978; Watanabe 2013) explanation how these are calculated.
### Multicollinearity plot of the covariates
The multicollinearity plot of the covariates for three species traits (activity period, size, and nesting strategy), distance from settlement, and vegetation characteristics (plant species richness, and canopy openness). The plot includes values within the boxes that indicate variance inflation factor (VIF), which quantifies the severity of multicollinearity. VIF values indicate minimal collinearity among covariates. Boxes without numbers indicate the VIF values were very small. Following Zuur et al. (2010), we applied a VIF threshold value of 3 and below to support low levels of multicollinearity.
### Plots for model validation to verify the presence of any residual patterns
The following figures show a posterior mean Pearson residuals versus posterior mean fitted values; b posterior mean Pearson residuals versus covariates; c semivariogram plot of posterior mean residuals for any spatial dependency
.
### Pearson residuals for each dung beetle species combination
AteC CanthiG CanthiK Canthisp1 Canthisp2 CanthonQ CanthonSemio CanthonT DelG DelO DelS DichB DichD
AteC − 0.3 − 0.2 − 0.1 0.1 − 0.2 − 0.1 − 0.1 − 0.1 0.2 0.2 0.5 − 0.2
CanthiG 0.1 0.2 − 0.1 0.1 − 0.3 − 0.3 0.2 − 0.3 0.0 − 0.3 − 0.2
CanthiK 0.2 0.2 − 0.2 0.1 − 0.1 − 0.1 0.0 0.1 − 0.1 0.0
Canthisp1 0.3 − 0.2 − 0.2 − 0.3 0.1 − 0.2 0.1 − 0.2 − 0.2
Canthisp2 − 0.1 − 0.1 − 0.2 − 0.1 − 0.2 0.0 − 0.1 − 0.2
CanthonQ 0.2 0.1 − 0.1 0.3 0.0 0.0 0.0
CanthonSemio 0.4 0.1 0.1 − 0.1 − 0.1 0.1
CanthonT − 0.1 0.0 − 0.3 − 0.1 0.0
DelG − 0.1 0.2 − 0.1 0.2
DelO 0.2 0.4 − 0.1
DelS 0.4 − 0.2
DichB − 0.2
DichD
DichL
DichM
DichP
EuryC
EuryH
EuryHy
OntR
OxyC
OxyF
OxyS
ScyC
SylB
Uro
AteC DichL DichM DichP EuryC EuryH EuryHy OntR OxyC OxyF OxyS ScyC SylB Uro
CanthiG 0.6 0.0 − 0.1 − 0.1 − 0.2 0.3 0.4 0.0 0.2 0.1 − 0.1 − 0.3 − 0.1
CanthiK − 0.1 − 0.3 − 0.1 0.1 − 0.1 − 0.3 − 0.1 − 0.2 0.1 0.1 0.1 0.0 − 0.3
Canthisp1 − 0.1 0.0 − 0.2 0.2 − 0.3 0.1 − 0.1 − 0.1 − 0.1 − 0.1 0.1 − 0.1 − 0.1
Canthisp2 0.1 − 0.2 0.2 0.4 0.0 − 0.2 − 0.1 − 0.2 − 0.1 − 0.1 0.2 0.0 0.0
CanthonQ 0.0 − 0.1 0.0 0.4 0.0 0.0 0.0 − 0.1 0.0 0.0 0.0 0.3 − 0.1
CanthonSemio − 0.2 0.1 0.2 − 0.1 0.2 0.0 − 0.2 − 0.1 − 0.1 − 0.1 − 0.1 0.0 0.0
CanthonT − 0.1 0.2 0.0 0.0 − 0.1 − 0.1 0.0 0.2 − 0.1 0.0 − 0.1 − 0.1 0.1
DelG − 0.2 0.5 0.0 − 0.1 0.3 0.0 − 0.1 0.0 − 0.2 − 0.2 − 0.2 0.0 0.2
DelO 0.0 − 0.2 0.0 0.0 0.0 − 0.1 − 0.1 − 0.2 − 0.1 0.2 0.1 0.0 − 0.1
DelS 0.1 0.2 0.0 − 0.2 0.0 0.1 − 0.1 0.1 0.0 0.0 0.1 − 0.3 0.1
DichB 0.2 − 0.2 − 0.3 − 0.1 0.1 0.1 − 0.1 − 0.2 0.1 − 0.1 0.6 − 0.1 − 0.2
DichD 0.2 0.1 − 0.1 − 0.1 − 0.2 0.3 0.2 0.0 0.0 − 0.1 0.1 − 0.1 − 0.1
DichL − 0.2 0.0 0.2 0.0 − 0.1 − 0.1 − 0.1 0.1 − 0.2 0.0 − 0.2 0.2 0.0
DichM − 0.1 − 0.1 0.0 − 0.1 0.0 0.2 0.0 0.1 0.1 − 0.1 − 0.3 − 0.2
DichP 0.1 − 0.1 − 0.1 − 0.1 − 0.1 0.2 − 0.2 − 0.1 − 0.2 0.0 0.0
EuryC 0.0 0.0 − 0.1 − 0.1 0.0 0.0 0.1 − 0.1 0.1 − 0.1
EuryH − 0.1 − 0.1 0.0 0.1 0.3 − 0.3 − 0.1 0.2 − 0.2
EuryHy − 0.2 − 0.2 0.0 0.0 0.0 0.2 0.0 − 0.1
OntR 0.5 0.0 0.1 0.0 0.1 0.0 0.0
OxyC 0.1 0.2 0.0 − 0.2 0.1 − 0.1
OxyF − 0.1 0.0 0.1 − 0.1 0.0
OxyS − 0.1 0.0 0.0 − 0.1
ScyC − 0.1 0.0 − 0.1
SylB 0.0 − 0.1
Uro − 0.1
### Results of WAIC, EAIC, and BIC for the latent variable model
Results of the widely applicable information criterion (WAIC), the expected Akaike information criterion (EAIC) and the expected Bayesian information criterion (BIC) comparing the latent variable models with 0, 1 and 2 latent axes. Values with asterisk indicate the preferred latent variable model with 0, 1, or 2 axes.
0 axis1 axis2 axes
WAIC1034.081778.5258447.1811*
EAIC1098.503920.0688758.1535*
EBIC1363.391*1454.04761557.0195
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### Cite this article
Choo, J., Gill, B.D., Zuur, A.F. et al. Impacts of an indigenous settlement on the taxonomic and functional structure of dung beetle communities in the Venezuelan Amazon. Biodivers Conserv 29, 207–228 (2020). https://doi.org/10.1007/s10531-019-01879-5
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### Keywords
• Disturbance
• Functional diversity
• Functional evenness
• Functional trait
• Jotï
• Human impact
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