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S0141938214000699 | Although the three-dimensional television is popular for its stereoscopy, the fatigue caused by the prolonged watching of 3DTV should not be underestimated. Electroencephalogram (EEG) has been widely used for monitoring the brain’s functional activities. Based on our previous research of 3DTV fatigue, one more objective and effective 3DTV fatigue evaluation model is proposed on gravity frequency of power spectrum and power spectral entropy. As the fatigue changes, the gravity frequency reflects the transition of EEG power spectrum and the power spectral entropy describes the level of chaos of EEG. 16 channels of EEG data of twenty-five subjects watching 2DTV and 3DTV were collected, and gravity frequency of power spectrum and power spectral entropy were then calculated and analyzed. These two parameters of the 3D group changed more significantly comparing with that of the 2D group on several electrodes. There are significant decreases in gravity frequency and power spectral entropy in several brain regions after long time of watching 3DTV, which indicates the decline of subjects’ alertness level. Based on the subjective evaluation and two significant parameters, gravity frequency and power spectral entropy, an accurate evaluation model for 3DTV fatigue was established using the regression equation. | Assessment visual fatigue of watching 3DTV using EEG power spectral parameters |
S0141938214000705 | Three kinds of lanthanide phosphors (La x Lu1 − x F3: Eu3+, LaF3–CaF2:Eu3+ and LaF3: Eu3+) have been successfully synthesized based on three different ways such as molten salts, co-precipitation, supersonic and microwave irradiations. The as-prepared powder materials all exhibited red luminescence. Their crystal structures or morphologies were studied by means of X-ray powder diffraction and scanning electronic microscope. Eu3+-doped LaF3–CaF2 phosphor can be emissive under excitation at longer wavelengths (466 and 533nm) excitations. Supersonic and microwave irradiations have shortened the reaction time of LaF3: Eu3+ crystals in 40min under very low temperature (50°C). | Design and characterization of new lanthanide fluorides and their optical properties |
S0141938214000717 | MEMS (microelectromechanical systems) are used in many fields including display applications, which are extensively studied both in academia and industry. For practical devices, numbers of advanced technologies have been developed based on MEMS concept. For display technologies, projection displays, reflective displays, transmissive displays and other display modes have been achieved by different MEMS modes. In this review, the current MEMS-based display technologies are introduced and discussed including digital micromirror device (DMD), laser scanning display (LSD), interferometric modulator display (IMOD), digital micro-shutter (DMS), time multiplexed optical shutter (TMOS), grating light valve (GLV) and others. The typical structure and fundamental of each display mode are interpreted. | Advanced MEMS-based technologies and displays |
S0141938214000729 | Polymer networks are employed in vertical-aligned liquid crystal (LC) cells to stabilize the LC molecular configuration under the in-plane field driving. Two different polymer morphologies, respectively produced by the monofunctional and bifunctional acrylate monomers, are assembled on the glass-substrate surface. The enhanced electro-optical performance is observed on the LC cell with bifunctional acrylate polymer networks, and the appropriate display cell is developed at an optimum concentration of 2wt%. This type of polymer-LC cell shows the fast turn-off and turn-on responses at the low driving voltage, which are attributed to the strong anchoring and the stable LC reorientations, respectively. Furthermore, around 30% improvement in the gray-level response on the 2-wt%-TA-9164-polymer-LC cell is successfully achieved, as compared to the pure LC cells. | Optimized electro-optical properties of polymer-stabilized vertical-aligned liquid crystal displays driven by an in-plane field |
S0141938214000791 | The relationship between the occurrence of simulator sickness (SS) and varying latency in a helmet-mounted display (HMD) was explored in this study. Previous work has always considered latency to be a constant. The aim of this research was to determine if a latency that varied over time would impact the experience of SS for HMD users. An object location task was used while viewing real, live video scenes via HMD. A planned comparisons approach was utilized with four experimental conditions, 2 of them having constant latency (0ms added to system baseline, 200ms added to system baseline) and 2 of them having sinusoidally varying latency (100ms amplitude at 0.2Hz frequency, and 20–100ms varying amplitude at 0.2Hz frequency). These conditions allowed for the assessment of the effects of constant latency vs. varying latency on the experience of SS. The results indicated that a varying latency is associated with greater experience of SS among HMD users than constant latency. Results also indicated, as has other recent research, that added constant latency on its own does not appear to be associated with the experience of higher levels of SS in an HMD. | The effects of 0.2Hz varying latency with 20–100ms varying amplitude on simulator sickness in a helmet mounted display |
S0141938214000808 | Thin amorphous silicon (a-Si) films were crystallized into polycrystalline silicon (poly-Si) by combining solid phase crystallization (SPC) and subsequent excimer laser annealing (ELA). Then thin film transistors (TFTs) were fabricated by using the poly-Si formed in the single and double excimer laser scanned area. The device performance of the TFTs fabricated with the excimer laser energy density of 230mJ/cm2 is almost equal for the single and double scanned area. This observation indicates that the overlapping laser irradiation with the laser energy density below 230mJ/cm2 does not change the characteristics of TFTs. Based on this result, we discuss the correlation between performance of active matrix organic light emitting display (AMOLED) panels and excimer laser energy density during ELA for SPC treated and non-treated poly-Si films. | Effects of the single and double (overlap) scanned excimer laser annealing on solid phase crystallized silicon films |
S0141938214000821 | Modern liquid crystal displays (LCDs) require novel technologies, such as new alignment methods to eliminate alignment layers, fast response and long operation time. To this end, we report an overview of recent efforts in LCD technologies devoted to realize more display modes having no alignment layer, faster switching time and low battery consumption. In particular, we overview recent advances on the liquid crystals (LCs) alignment for display applications, which includes superfine nanostructures, polymeric microchannels and polymer stabilized LCs. Furthermore, we analyze the main optical and electro-optical properties of new generation LCDs displays addressing a particular attention to LCs blue phase hosting gold nanoparticles. Moreover, we focus on the progress of electrofluidic displays, which demonstrates characteristics that are similar to LCDs, with attention on various pixel designs, operation principles and possible future trends of the technology. | Developing novel liquid crystal technologies for display and photonic applications |
S0141938214000833 | We examined the effects of the visual size and the number of digits on reading numerical time information in young adults. Using an adaptive staircase procedure, minimal stimulus presentation duration (MSPD) for 80%-correct responses was determined for visual sizes ranging from 0.1° to 15°, when reading 1 (“mm”), 2 (“hh:mm”) or 3 (“hh:mm:ss”) 2-digit units of time information. All three time types revealed U-shaped relations between MSPD and visual size, with the characteristics of the relation depending on the number of time units. Time type had two different effects. First, longer time types gave rise to longer MSPDs, as more elements needed to be encoded into working memory. Second, longer time types gave rise to smaller ranges of optimal visual character size, decreasing from 0.2–2° for the 1-unit time type to 0.3–0.5° for the 3-unit time type. The lower boundary of the optimal range of visual size may be understood as resulting from acuity limitations. The shift in the upper boundary of the optimal range of visual size is suggested to reflect the change in size of the visual span associated with larger visual character sizes. | Stimulus duration thresholds for reading numerical time information: Effects of visual size and number of time units |
S0141938214000870 | This paper discusses state-of-the-art tactile displays fabricated by a micro-electronic-mechanical-system (MEMS). A tactile display conveys tactile sensations to users by using actuators. Traditional tactile displays consist of large size actuators, such as a motor or an ultrasound vibrator, to convey tactile feedback by vibration. In addition, the tactile sensation of traditional displays has poor resolution. Microelectromechanical system (MEMS) technology, which is a miniature fabrication process, enables etching, sputtering and assembling of miniature structures. Recently, the technology was applied to tactile displays. For example, shape memory alloy (SMA) actuators are widely used in tactile displays to convey roughness or vibration. The actuators are fabricated by a sputtering process and then thinned. The displays convey various tactile sensations, including feedback and tactile sensations of objects such as paper or wood. This paper is a review of tactile displays fabricated by MEMS technology. We also describe the fabrication processes and stimulation methods to present the potential and applications of the displays. | MEMS-based tactile displays |
S0141938214000882 | This work presents the possibility of the hollow core nanoparticles to improve luminance in an organic light emitting diode device. The finite difference time domain simulation estimates the effect of the hollow core nanoparticles on the external quantum efficiency of the organic light emitting diode device. The efficiency depends on the size and the volume fraction of the hollow core nanoparticles in the polymer layer, together with the refractive index and the thickness of the polymer layer. It is shown that the hollow core nanoparticles dispersed in a polymer layer can enhance the external quantum efficiency by a factor of 2.5. This work also introduces a continuous production method of the hollow core nanoparticles by using the microfluidic self-assembly of amphiphilic polymers and the layer formation dispersed with them for the rigorous light scattering. | Hollow-core polymeric nanoparticles for the enhancement of OLED outcoupling efficiency |
S0141938214000894 | New chiral compounds of the steroid type, namely, 3-alkanoyl- and 3-alkyl derivatives of 16-arylidene estrone, were synthesized and exhibited high helical twisting power (HTP) in nematic liquid crystals E63 and LC-1289. The peculiarities of the molecular structure of chiral compounds (CCs) and their high degree of chirality were discussed. Quite small concentrations of chiral compounds in both nematic solvents were needed to obtain a short-pitch cholesteric helical macrostructure with the selective light reflection in the visible range of the spectrum. The insignificant temperature dependence of the maximum wavelength of the selective light reflection obtained on the whole cholesteric range for all studied liquid crystalline (LC) systems could be related to relatively rigid molecular structure of the chiral compounds. The cholesteric LC mixtures comprising 3-alkanoyl- and 3-alkyl derivatives of 16-arylidene estrone were characterized by the phase stability and the stability of reflective characteristics in time that makes it possible to consider this series of dopants as appropriate for development of bistable cholesteric reflective LC displays. | Influence of the rigidity of the steroid core in the structure of chiral dopants on the temperature dependence of cholesteric short pitch |
S0141938214000912 | In this paper we investigated the accuracy of center-to-center distance perception in near field augmented reality visual targets viewed by stereoscopic glasses. One real and one virtual targets were presented in four layout or target orientations (two horizontal and two vertical, by altering the relative positions of real and virtual targets) at three different parallax conditions (on screen, 5cm from screen and 10cm from screen) and four levels of scaled between targets’ distance (10–20cm, 20–30cm, 30–40cm and 40–50cm). The result revealed overall underestimation with an accuracy of about 84%. Interestingly, it was noticed that the main effects of layout, parallax and center-to-center distance were significant. Generally, accuracy improves when targets put vertical, close to observers’ position and smaller separation of targets. Significant interactions among the three main factors were also reported. The results are of great importance as it provides guide for the developers to decide where to present targets depending on the need for relative accuracy of judgment. Some engineering implications of the result are also discussed in this paper. | Distance estimation with mixed real and virtual targets in stereoscopic displays |
S0141938214000924 | This paper reviews several optical connecting devices that are based on microelectromechanical systems (MEMS) components. In this paper, we divide optical connecting devices into two categories. The first category includes MEMS-based optical switches developed for optical fiber communication, which perform optical switching, wavelength division multiplexing (WDM) routing, and/or optical cross connection. The other category consists of MEMS-based optical interconnects that have been constructed primarily for use in rack-to-rack, board-to-board, chip-to-chip, card-to-card and/or intra-chip interface connections. Working principles of these MEMS optical connecting devices will also be discussed in this paper. | MEMS optical switches and interconnects |
S0141938214000936 | Fiber-optical microendoscopy has recently been an essential medical diagnostic tool for patients in investigating tissues in vivo due to affordable cost, high quality imaging performance, compact size, high-speed imaging, and flexible movement. Microelectromechanical systems (MEMS) scanner technology has been playing a key role in shaping the miniaturization and enabling high-speed imaging of fiber-optical microendoscopy for over 20years. In this article, both review of MEMS based fiber-optical microendoscopy for optical coherence tomography, confocal, and two-photon imaging will be discussed. These advanced optical endoscopic imaging modalities provide cellular and molecular features with deep tissue penetration enabling guided resections and early cancer assessment. | MEMS based fiber optical microendoscopes |
S0141938215000025 | A film-insert injection compression molding process was introduced to encapsulate cholesteric liquid crystal displays with flexible and rigid lens for full protection of displays to replace the currently used time consuming hand lamination technique. For this purpose, a new interchangeable cavity instrumented hot runner mold was designed and constructed. This complex method was carefully optimized considering challenges arising from an insert multilayer display with +80% liquid crystal content as well as different thermal expansion coefficients between the layers and the lens material as a high potential of delamination and warpage. Concerning the desired physical properties including transparency, low melt viscosity and melting temperature as well as a wide range of hardness grades from soft (flexible) to hard (rigid), three different hardness grades of thermoplastic polyurethanes were found to be the best candidates for this lens application. During proposed lens encapsulation, the pressure changes were evaluated with screw and mold movements using position detection via displacement transducers attached to track the mold closure and screw forward motion. The quality of encapsulation and shrinkage related problems, as well as their elimination, were all discussed. Display substrate material selection criteria for lowered warpage were defined with supporting thermal characterizations. Among the process parameters, tested also by applying the design of experiments with Taguchi method, mold temperature was found to be the most influential parameter on warpage, followed by pin gate opening time, packing pressure, and cooling time. | Instrumented film-insert injection compression molding for lens encapsulation of liquid crystal displays |
S0141938215000037 | In many virtual environments, such as those of video games, the scene background moves to give the illusion of movement. In the present study, two experiments were designed to investigate the combined impact of lateral background motion and task difficulty on players’ performance in a target-shooting task. Participants had to perform the task on either the moving or the stationary version of a patterned background that was either green (Experiment 1) or black-and-white (Experiment 2). The difficulty of the task was manipulated by varying the number of visual features shared between the target and distractor items. In accordance with the literature, the participants’ performance was worse, and the number and duration of participants’ fixations increased when the task was difficult. Background motion had an additive, negative impact on performance. When the background was black-and-white, background motion had an impact only when the task was easy but not when it was difficult. Design recommendations based on manipulations of the background characteristics are proposed to establish the level of difficulty in simple video games that use lateral background motion. | How visual background motion and task difficulty modulate players’ performance in a shooting task |
S0141938215000293 | The effect of 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) doping on electroluminescent properties of poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (poly-TPD) was investigated. A series of organic light-emitting devices (OLEDs) integrated with (i) single-layer poly-TPD, (ii) blended single-layer poly-TPD:TPBi or (iii) bilayer poly-TPD/TPBi were fabricated and characterized. An excimer emission band at 500nm was found in the poly-TPD film, poly-TPD:TPBi (1:1) blend film, and poly-TPD/TPBi bilayer film. It was observed that the planar geometry of poly-TPD was related to the formation of excimers. The electromer emission, which was absent in photoluminescence, was investigated by applying an external electrical field to devices with non-doped and TPBi-doped poly-TPD. Only the electromer emission was observed in the devices with TPBi-doped poly-TPD, due to the impeded intrinsic and excimer emissions. The planar geometry of poly-TPD molecules may be destroyed due to the longer inter-ion distance with the doping of TPBi. | Electroluminescent properties of poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] doped with 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene |
S0141938215000311 | Using a ray tracing technique, we investigate the dependence of the moiré effect on the crossing angles between touch screen panels (TSPs) and display panels, the metal grid structures (spacing and width), and metal grid shapes (non-uniform and random grids). Of those design parameters, adjusting the crossing angle (∼45°), reducing the grid width (∼1μm), and employing a random grid in the shape of irregular hexagon are found to suppress the moiré phenomenon to a great extent. We also provide the simulation scheme that can capture the moiré patterns observed experimentally and useful design guidelines for metal grids. | Design of moiré-free metal meshes using ray tracing for touch screen panels |
S0141938215000323 | When reading from an electronic screen, many individuals report symptoms such as tired eyes or eye strain. To minimize these symptoms, a 3× acuity reserve has been suggested, i.e., the minimum print size should be at least 3 times larger than the size of the letters at the reader’s acuity limit. This study evaluated whether the 3× rule is appropriate, or if an alternative relationship between visual acuity and letter size would be preferable. The experiment was performed on 25 visually-normal subjects who viewed a series of random words on a computer monitor. The threshold distance (T) at which the text could be resolved was determined. Both reading speed and accuracy were measured during a 10min task performed at T and at 0.5T, 0.33T and 0.25T. In a second study, the procedure was repeated at 0.5T and 0.33T for 1h. Immediately following the 1h trial, subjects completed a questionnaire concerning symptoms experienced during the task. The mean T for the 10min trial was 131.4cm. While the mean reading speeds for the 0.5T, 0.33T and 0.25T conditions were significantly different from the 1T condition, they were not significantly different from each other. For the 1h trial, reading speed at 1T was significantly different from both the 0.5T and 0.33T conditions, but no significant difference was observed between the 0.5T and 0.33T trials. A significant increase in the total post-task symptoms was found after reading at the threshold distance (T), compared with 0.5T and 0.25T, but no significant difference in symptom score was found between the 0.5T and 0.25T conditions. Accordingly, based on a change in viewing distance (and angular print size) in young, visually-normal subjects, a 2× rule may be appropriate, i.e., for sustained comfortable reading, the text size should be at least twice the individual’s visual acuity. However, higher values may be necessary for older subjects, or individuals with visual abnormalities. | Is the 3× reading rule appropriate for computer users? |
S0141938215000335 | Minimum angle of resolution (MAR) was measured for the grating which consisted of lines of two colors selected from Red, Green, Blue, White and Black. Method of two alternative forced choice (2AFC) was used where the participants were asked to answer the direction of the color grating of the horizontal or vertical directions. From the measured psychometric function of the ratio of the correct answers, MAR which corresponded to the threshold of 75% correct answer ratio was determined. MAR of the grating patches with more than one primary color was measured to be affected by the combination of colors and to be 10–30% larger than that of the grating patch of White–Black. While the resolving power for Blue pattern had been known to be worse than those for Green and Red patterns, MAR of the grating including Blue was not always the worst. | Measurement of minimum angle of resolution (MAR) for the spatial grating consisting of lines of two colors |
S0141938215000347 | Background The use of colors in visual displays can facilitate visual search and perception, but their use may not be effective without consideration of differences in the interpretation of their connoted meanings between individuals of different occupational backgrounds. Objective This study examined color-concept associations for Hong Kong Chinese students and white-collar workers, and then compared their associations with those of two other occupational groups to assess whether occupational background is related to color-concept associations. Method A questionnaire survey was used to examine color-concept associations among 100 university students and 100 white-collar workers in Hong Kong. The participants were presented with 16 safety-related concepts and were asked to choose one of 10 colors that best represented each concept. The associations reported by four groups with different occupations (the two groups in this study and the groups of managerial staff and steel workers examined in our previous study) were compared. A chi-square test was applied to determine whether significant color association(s) existed for each concept. Results Our results revealed that each concept was significantly associated with at least one color (p < 0.01). The Hong Kong white-collar workers and managerial staff in mainland China both expressed the same color associations for 14 of the tested concepts, and differed only over which colors were associated with “strong,” and “radiation hazard.” These findings generally suggest that populations with similar occupations can have similar color perceptions. However, the students and the other three employee groups reported different color associations with the concepts “normal,” “off” and “potential hazard.” Conclusions Occupational background is associated with how color is interpreted for its connoted meaning. One should consider occupational background carefully when choosing colors in product designs, especially for safety. | A study of the relationship between color-concept association and occupational background for Chinese |
S0141938215000529 | Objective It is generally assumed that motion in motion images is responsible for increased postural sway as well as for visually induced motion sickness (VIMS). However, this has not yet been tested. To that end, we studied postural sway and VIMS induced by motion and still images. Method 15 Participants were exposed to motion- and still images in separate sessions. Motion images consisted of video clips taken from a first person shooter game. Still images consisted of stills taken every 10s from these same clips. Before, during, and after exposure, VIMS was rated and postural sway was measured. Sway path length, standard deviation and short- and long-term scaling components of the centre of pressure were calculated as measures of postural sway. Results VIMS scores obtained during and after exposure to motion images were significantly higher compared to scores obtained before, and directly after exposure to still images. The sway path length, standard deviation in anteroposterior direction and short-term scaling components in mediolateral and anteroposterior direction increased significantly during exposure to motion and still images. Conclusion In this experiment motion- and still images caused different levels of VIMS, but comparable increases in postural sway. We assume VIMS was caused by a mismatch between visual and vestibular motion cues. The increase in sway during exposure to still images can be explained by visual effects present in still images. The lack of vection in the motion images may explain why sway was not larger when viewing these motion images as compared to viewing the still images. | Motion in images is essential to cause motion sickness symptoms, but not to increase postural sway |
S0141938215000530 | Dysprosium doped strontium calcium magnesium di-silicate phosphor namely: SrCaMgSi2O7:Dy3+ was prepared by the solid state reaction method. The crystal structure of the prepared phosphor was an akermanite type structure, which belongs to the tetragonal crystallography with space group P 42 ‾ 1 m. From field emission scanning electron microscopy (FESEM), agglomerations of particles were observed due to the high temperature synthesis process. The chemical composition of the sintered SrCaMgSi2O7:Dy3+ phosphor was confirmed by energy dispersive X-ray spectroscopy (EDX). Under the ultra-violet (UV) excitation, the characteristic emission of Dy3+ ions peaking at 478, 580 and 674nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+. Commission International de I’Eclairage (CIE) color coordinates of SrCaMgSi2O7:Dy3+ are suitable as white light emitting phosphor. Decay graph indicate that this phosphor contains fast decay and slow decay process. The mechanoluminescence (ML) intensity of SrCaMgSi2O7:Dy3+ phosphor increases linearly with increasing impact velocity of the moving piston, which suggests that this phosphor can be used as sensors to detect the stress of an object. Thus the present investigation indicates that the piezo-electrically induced de-trapping model is responsible to produce ML in SrCaMgSi2O7:Dy3+ phosphor. The possible mechanism of white light emitting long lasting phosphor is also investigated. | Structural characterization and optical properties of dysprosium doped strontium calcium magnesium di-silicate phosphor by solid state reaction method |
S0141938215000542 | The Spectral Radiance Piecewise Partition Model (SRPPM) is a new model for characterizing Liquid Crystal Displays (LCD). According to the additive property of the spectral radiances of the primary displayed color, the SRPPM model can be divided into three subspace partitions to calculate the transfer coefficient matrixes with cubic polynomial, which based on the relationship between the digital input of the LCD and the spectral radiance of displayed color. The color difference was used to evaluate the accuracy of this model. Comparing with other characterization models for LCD, the experimental results show that the average color difference of SRPPM is 0.82ΔE 76, and 80% of the color differences between color samples are less than 1ΔE 76. | The Spectral Radiance Piecewise Partition Model for characterizing Liquid Crystal Displays |
S0141938215000554 | Blue organic light-emitting devices (OLEDs) combing a composite hole transporting layer (c-HTL) and novel homogeneous double emitting layers (DELs) have been fabricated. The c-HTL plays a significant role of rectification in balancing the carriers’ injection concentration which matches well with the DELs structure. The DELs is consisted of two homogeneous hosts, such as 2-methyl-9,10-di(2-naphthyl) anthracene (MADN) and 9,10-di(2-naphthyl) anthracene (ADN). The optimal device presents the maximal current efficiency of 15.9cd/A at 4.9mA/cm2 and the minor efficiency roll-off of 13.4% under the driving voltage varying from 5V to 10V, respectively. Meanwhile, the device’s maximal current efficiency and the corresponding efficiency roll-off have been obviously improved by 55.9% and 63.9% compared with those of the conventional device. These results indicate that the homogeneous DELs not only greatly facilitate carriers’ injection into the emitting layer (EML), but also evenly modulate carriers’ distribution due to natural energy barrier of the interface. The transient photoluminescence decay of double hosts further illustrates that the DELs structure can increase the recombination ratio of electron–hole pairs and improve the exciton’s utilization. Additionally, the optimal device’ current density is reduced by 44.1% under the same luminance of 25,780cd/m2 compared with that of the conventional device. | Utilization of a composite hole transporting layer and novel homogeneous double emitting layers for performance improvement and low efficiency roll-off in organic light-emitting diodes |
S0141938215000566 | This study explores a new way to integrate advanced display technology into educational activities for children with different disabilities. A free interactive mobile augmented reality (AR) application was developed to facilitate the learning of geometry. Twenty-one elementary school children participated in an experiment. The results show that the AR system could help the school children to finish puzzle game activities independent of teacher’s assistance. With the use of AR display technology, the participants demonstrated improved ability to complete puzzle game tasks when compared to the use of traditional paper-based methods. Performance data indicated that the use of AR technology could enhance learning motivation and frustration tolerance in children with special needs. | Augmented reality in educational activities for children with disabilities |
S0141938215000578 | Industrial and academic researches have, in the last twenty years, matured the plasma display panels (PDPs) to the successful product level for commercial flat screen television sets. The sustain driver with resonant operation, converting high dc voltage to ac square-wave voltage with high frequency for strong visible light emission, have great influence on the entire circuit efficiency and cost, from driving circuit point. Although circuit losses and costs of PDP drivers are of the utmost importance, comparative study of the sustain drivers has been missed in literature, despite numerous publications for PDP drivers. This paper, in detail, presents the theoretical analyses and systematic comparisons of the PDP drivers, in terms of switch current and voltage ratings. Based on analytical expressions and comparative features, the sustain drivers are evaluated from standpoint of switch ratings. | Rating analysis and comparisons of resonant circuit based sustain drivers for PDPs |
S0141938215000591 | After the appearance of digital broadcasting, realistic images such as 3D and high resolution broadcasting are rapidly developing and evolving. And, recent trend emphasizes not only viewing the information but also using it through the display media. To keep up with this trend, large size display manufacturers are trying to support resolution beyond the full HD, in order to display additional information and high definition broadcasting at the same time. In this paper, we present a 21:9 cinema mode resolution (2560×1080) function using two ICs that support full HD for Plasma Display Panels (PDPs) which is one of the largest flat display panels. In order to achieve this, we first set the master and the slave between the two ICs, and propose an efficient information exchange and computation scheme using serial communication that links the master and the slave. Furthermore, we realize the cinema function with 21:9 resolution through image quality processing and operational parameter exchange and computation in the boundary that is set between the master and the slave. Finally, the cinema mode image realized using the hardware circuit board is demonstrated. | Implementation of 21:9 cinema mode function using two ICs supporting full HD resolution |
S0141938215000608 | 3D video has recently seen a massive increase in exposure in our lives. However, differences between the viewing and shooting conditions for a film lead to disparities between the reformed media and the original three-dimensional effect, which cause severe visual fatigue to viewers and result in headaches and dizziness. In this paper, a series of image processing algorithms are introduced to overcome these problems. The image processing pipeline is composed of four steps, eye-pupil detection, stereo correspondence computation, saliency map generation, and 3D warping. Each step is implemented in an S3DS-3D rendering system and its time complexity is measured. From the results, it was found that real-time stereoscopic 3D rendering is impossible using only a software implementation because SIFT and optical flow calculation requires a significant amount of time. Therefore, these two algorithm blocks should be implemented with hardware acceleration. Fortunately, active research is being conducted on these issues and real-time processing is expected to become available soon for applications beyond full-HD TV screens. In addition, it was found that saliency map generation and 3D warping blocks also need to be implemented in hardware for full-HD display although they do not have significant time complexity compared to SIFT and optical flow algorithm blocks. | A study on the possibility of implementing a real-time stereoscopic 3D rendering TV system |
S0141938215000621 | Two phenylanthracene-substituted fluorene derivatives, 10-(9,9′-dimethyl-2-(10-phenylanthracen-9-yl)-9H-fluoren-7-yl)-phenylanthracene (1) and 2′,7′-di-(10-phenylanthracen-9-yl)-9,9′-spirobi[9H-fluorene] (2) have been designed, synthesized, and characterized. A device using compound 1 as an emitting material exhibited luminous efficiency, power efficiency, external quantum efficiency and CIE coordinates of 3.37cd/A, 1.50lm/W, 1.87% at 20mA/cm2 and (0.18, 0.25) at 7V, respectively. Furthermore, by exploiting this efficient blue fluorescent material as a blue emitting material with the combination of red phosphorescent bis(2-phenylquinoline)acetylacetonate [(pq)2Ir(acac)], an efficient white OLED (WOLED) with a external quantum efficiency of 1.70%, luminous efficiency of 1.38cd/A, power efficiency of 0.94lm/W at 20mA/cm2 and the color coordinates of (0.33, 0.36) at 14V is demonstrated. | Blue electroluminescent materials based on phenylanthracene-substituted fluorene derivatives for organic light-emitting diodes |
S0141938215000906 | GdVO4:Eu3+, Bi3+ with tetragonal phase has been successfully synthesized by employing efficient irradiations. The assembly of composites with fine grains based on acoustic energy and microwave radiation requires low temperature (90°C) and short reaction time (60min). All the compounds exhibited red emissions and they can be sensitized through the doped Bi3+ ions. The dependence of pH changes and doping concentration on the fluorescence features has been discussed. The photoluminescence measurements show that the optical properties achieved the best results at pH=9 for GdVO4:Eu3+(5mol%), Bi3+(1mol%) or pH=7 for GdVO4:Eu3+. | Facile synthesis of lanthanide vanadates and their luminescent properties |
S0141938215000918 | A scalable video coding (SVC) server can simultaneously provide a single bitstream with a fixed maximum service layer for different kinds of devices having different memory capacity, network bandwidth, and CPU performance requirements. An efficient hybrid 3D video service scheme is proposed without violation of the SVC standard technology for multiple transmission paths. A dynamic local disparity vector estimation algorithm is used to reflect the motion shift component between stereo views in the inter-layer prediction stage of the SVC encoder. To improve the coding efficiency, an adaptive search scheme based on distortion rates (DRs) between corresponding and reference macroblocks is used. Based on experimental results, up to 1.41dB of quality improvement using JSVM 9.19 reference software is verified. | A novel hybrid 3D video service algorithm based on scalable video coding (SVC) technology |
S0141938215000931 | This paper proposes a fast mode decision algorithm for 3D High Efficiency Video Coding (3D-HEVC) depth intra coding. In the current 3D-HEVC design, it is observed that for most of the cases, full rate-distortion (RD) cost search of Bi-Partition mode could be skipped since most coding units (CUs) of depth map are very flat or smooth while Bi-Partition modes are designed for CUs with edge or sharp transition. Using the rough RD cost value calculated by HEVC Rough Mode Decision as a selection threshold, we propose a fast Bi-Partition modes selection algorithm to speed up the encoding process. The test result for the proposed fast algorithm reports a 34.4% encoding time saving with a 0.3% bitrate increase on synthesized views for the All-Intra test case and negligible impact under the random access test case. Moreover, by simply varying the selection threshold, we can make a tradeoff between encoding time saving and bitrate loss based on the requirement of different applications. | Low complexity Bi-Partition mode selection for 3D video depth intra coding |
S0141938215000943 | In general, to achieve high compression efficiency, a 2D image or a 2D block is used as the compression unit. However, 2D compression requires a large memory size and long latency when input data are received in a raster scan order that is common in existing TV systems. To address this problem, a 1D compression algorithm that uses a 1D block as the compression unit is proposed. 1D set partitioning in hierarchical trees (SPIHT) is an effective compression algorithm that fits the encoded bit length to the target bit length precisely. However, the 1D SPIHT can have low compression efficiency because 1D discrete wavelet transform (DWT) cannot make use of the redundancy in the vertical direction. This paper proposes two schemes for improving compression efficiency in the 1D SPIHT. First, a hybrid coding scheme that uses different coding algorithms for the low and high frequency bands is proposed. For the low-pass band, a differential pulse code modulation–variable length coding (DPCM–VLC) is adopted, whereas a 1D SPIHT is used for the high-pass band. Second, a scheme that determines the target bit length of each block by using spatial correlation with a minimal increase in complexity is proposed. Experimental results show that the proposed algorithm improves the average peak signal to noise ratio (PSNR) by 2.97dB compared with the conventional 1D SPIHT algorithm. With the hardware implementation, the throughputs of both encoder and decoder designs are 6.15Gbps, and gate counts of encoder and decoder designs are 42.8K and 57.7K, respectively. | An enhanced one-dimensional SPIHT algorithm and its implementation for TV systems |
S0141938215000955 | Multi-projector displays allow the realization of large and immersive projection environments by allowing the tiling of projections from multiple projectors. Such tiled displays require real time geometrical warping of the content that is being projected from each projector. This geometrical warping is a computationally intensive operation and is typically applied using high-end graphics processing units (GPUs) that are able to process a defined number of projector channels. Furthermore, this limits the applicability of such multi-projector display systems only to the content that is being generated using desktop based systems. In this paper we propose a platform independent FPGA based scalable hardware architecture for geometric correction of projected content that allows addition of each projector channel at a fractional increase in logic area. The proposed scheme provides real time correction of HD quality video streams and thus enables the use of this technology for embedded and standalone devices. | A scalable architecture for geometric correction of multi-projector display systems |
S0141938215000967 | An increasing number of studies on efficient implementation of vivid and realistic displays are being conducted as liquid crystal displays (LCDs) become widely used in TV applications. For vivid displays, the specifications such as wide color gamut (WCG) and high dynamic range (HDR) should be implemented in LCDs. However, the low transmittance rate of the WCG and the significant costs for the peak luminance capability of the HDR are major obstacles. Hence, an RGBW LCD, which is capable of increasing the transmission efficiency, may be a good platform to overcome these problems. In this paper, we estimate the perceived brightness effect of the WCG by using the Helmholtz–Kohlrausch (H–K) effect on RGB and RGBW LCDs. The simulation results showed that the RGBW LCD was more suitable for adopting the WCG than the RGB LCD in terms of the brightness balance of achromatic and chromatic colors, and the results were also confirmed by subjective tests. In addition, we propose an effective method to implement the HDR display based on the RGBW LCD. The data stretch, considering a local adaptation characteristic of a human visual system (HVS), greatly enhanced the details of the dark regions, and the local peak dimming using the white channel analysis and the white channel data itself increased the expressiveness of the peak luminance in irradiative or specular regions to 1500nits. | Wide color gamut and high dynamic range displays using RGBW LCDs |
S0141938215000979 | HEVC is the latest coding standard to improve the coding efficiency by a factor of two over the previous H.264/AVC standard at the cost of the increased complexity of computation rate-distortion optimization (RDO) is one of the computationally demanding operations in HEVC and makes it difficult to process the HEVC compression in real time with a reasonable computing power. This paper aims to present various simplified RDO algorithms with the evaluation of their RD performance and computational complexity. The algorithms for the simplified estimation of the sum of squared error (SSE) and context-adaptive binary arithmetic coding (CABAC) proposed for H.264/AVC are reviewed and then they are applied to the simplification of HEVC RDO. By modifying the previous algorithm for H.264/AVC, a new simplified RDO algorithm is proposed for modifying the previous algorithm for H.264/AVC to be optimized for the hierarchical coding structure of HEVC. Further simplification is attempted to avoid the transforms operations in RDO. The effectiveness of the existing H.264/AVC algorithms as well as the proposed algorithms targeted for HEVC is evaluated and the trade-off relationship between the RD performance and computational complexity is presented for various simplification algorithms. Experimental results show that reasonable combinations of RDO algorithms reduce the computation by 80–85% at the sacrifice of the BD-BR by 3.46–5.93% for low-delay configuration. | Simplified algorithms for rate-distortion optimization in high efficiency video coding |
S0141938215300019 | Panoramic videos provide a high resolution wide-angle field of view to audience. The rendering of such panoramic videos on large multi-projector curved displays further enhances the experience by providing them an immersive visual environment. Immersive panoramic projection thus comprise of three steps: acquisition of videos, stitching of video frames and their projection using multi-projector display system. Both panoramic stitching and multi-projector rendering require compute intensive geometric and photometric transformations that have to be applied for each frame of a video during stitching as well as rendering process. In this paper, we propose a unified scheme that handles these two separate geometric transformations using a single, combined Look up Table (LUT). The scheme allows projection of planar and cylindrical panoramas on curved cylindrical displays. Experimental results show that the proposed scheme provides a speedup of up to 73% and 83% for projector resolutions of HD and 4K respectively, for a two-camera two-projector panoramic display system. Furthermore, for a 4K projector, the proposed scheme requires 2.278ms for the geometric transformation of its content, thus enabling real time panoramic video projection. | A unified panoramic stitching and multi-projector rendering scheme for immersive panoramic displays |
S0141938215300020 | This paper presents a novel image restoration algorithm using examples and truncated constrained least squares (TCLS) filter for ultra-high definition (UHD) television systems. The proposed approach consists of three steps: (i) generation of the patch dictionary using multiple-step image blurring, (ii) selection of the optimum patch based on the orientation and the amount of blurring, and (iii) combination of the selected patch in the dictionary and its filtered version by the TCLS restoration filter for reducing the patch mismatch error. In the proposed algorithm, a complicated point-spread-function (PSF) estimation process is replaced with the generation of multiple, differently blurred patches. Furthermore, the patch dictionary is made by orientation-based classification to reduce the time to search the optimum patch. Experimental results show that the proposed algorithm can restore more natural images with less synthetic artifacts than existing methods. The proposed method provides a significantly improved restoration performance over existing methods in the sense of both subjective and objective measures including peak-to-peak signal-to-noise ratio (PSNR) and structural similarity measure (SSIM). | UHD TV image enhancement using example-based spatially adaptive image restoration filter |
S0141938215300032 | With the spread of portable smart devices, social networking services are gaining popularity. At the same time, emoticons which can be used a primary tool to deliver the enriched personal feelings are also gaining popularity in the social networking services. Now, emoticon markets are much bigger than before since the territory of emoticons broadens the culture and social issues. However, provided emoticons from the service providers are difficult to express the exact personalized feeling. Thus, users cannot edit what they want to express. In this study, we propose a new concept of emoticons, an editable visual object, to resolve above problems. User can edit the components inside the proposed editable visual object and send it to express exact intention. Further, we propose an efficient editable visual object description schema to represent and transmit the editable visual object. To prove the performance and efficiency of proposed technique, we implement and test the prototype system for the mobile device. As shown in the test results, the proposed description method is at most 100 times superior to the compared screen capturing method in the view of transmission bandwidth. The proposed editable visual object can be exploited not only mobile applications, but also various fields such as education and medical field. | Introduction to editable visual object and its description schema for mobile applications |
S0141938215300044 | 3D has been one of the most important technologies of the last decade having an exponential progression. Nevertheless, several problems such as visual discomfort and visual fatigue have slowed its progression for homes. This factor decreases significantly the overall quality of experience from watching 3D content and reduces the level of satisfaction of a user. This study explores the accumulation of visual fatigue when watching 3D video in close to real-life conditions. In order to obtain more information about visual discomfort, an hour of eye-tracking experiments have been conducted. Investigations have been made by analyzing information provided both by users through questionnaires and visual gaze characteristics recording. Obtained results are compared to data produced when watching 2D. The deep statistical analysis showed that time and video content have an influence on video fatigue accumulation and visual functions. With respect to the obtained results, a model has been proposed based on video characteristics (motion activity, disparity range and changes) and the previous state of visual fatigue. | Investigation and modeling of visual fatigue caused by S3D content using eye-tracking |
S0141938215300056 | The aim of this study is to develop an effective method to analyze regions of interest (ROIs). Two experiments were conducted at different times using different groups of observers with different images on different displays. Observers’ eye-movement data were collected. Fixation maps showing CIELAB L ∗ values were created. The ΔL ∗ values between the two maps were used to quantify differences in visual fields, counting methods, observer variability and repeatability between the two experiments. The results showed that fixation maps can be used to effectively analyze the distribution of eye movements between images. The ΔL ∗ value calculated for two fixation maps is easy to understand and computes differences based only on ROIs more effectively than differences based on the entire image. The results from the two experiments were consistent, indicating that eye-tracking data are robust for evaluating image quality. | Identifying regions of interest in reading an image |
S0141938215300068 | This study evaluates the effect of presentation media (PC tablet versus pencil and paper) on the performance, level of visual fatigue, and subjective preference of those taking visuospatial tests. Fifty university students participated and performed three visuospatial short-term memory tests and three visuospatial ability tests by using both types of display media. The display medium substantially affected all of the measured variables (p <0.01). On average, the paper–pencil test scores of the visuospatial short-term memory tests were about 10% higher and the answer time was about 20% shorter than those of the PC tablet tests. The average paper–pencil test score of the visuospatial ability tests was about 35% higher than the average test score of the PC tablet test. The visuospatial performance was substantially decreased under the PC tablet condition compared with that under the pencil–paper condition. In addition, visual fatigue was greater when participants used the PC tablet than when they used a pencil and paper. | The evaluation of visuospatial performance between screen and paper |
S0141938215300081 | Anaglyph video (i.e., 3D video) is a recent trend in movies and multimedia; the method has also been recently developed for conversion of such videos from traditional 2D screens or by rendering stereoscopic media into 3D video. There have also been many studies regarding movie playing and other types of entertainment that uses olfactory displays or smell generators. These devices are capable of generating a considerable number of different odors with different intensities yet still have some limitations and are not ready for commercial use. In this study, a complete solution is presented for a user to experience olfactory sensations with a displayed video on a PC with auditory and 3D visual effects using a novel olfactory display device based on a micro-porous piezoelectric film that is capable of digitally producing fine particles of scent material with precision, quantity and speed. | Anaglyph video smell presentation using micro-porous piezoelectric film olfactory display |
S0141938215300093 | Icon plays a critical role in computer interface design. Studies on icon taxonomy explain the way in which various types of icon represent the objects and provide designers creation rules by which icons are more in line with users’ cognitive psychology. However, along with larger and larger use of icons, the previous classification criterion causes the boundary between categories blur. What’s more, Single classification standard is not able to well illustrate the icons applied in today’s computer applications. The purpose of this paper is to present an objective-oriented icon taxonomy which proposes to categorize icons into action icon and knowledge icon. To assess this proposition, we analyzed a sample of icons that applied in computer interface and suggest precise application domains to both action icon and knowledge icon categories. The results of this practice manifested that action icon and knowledge icon implied a high relation with applied environment and explicated the development trace of computer icons. This work is one of the first to point out the notion of knowledge icon and to highlight the importance of objective of icon application. Findings in this paper could enrich icon use in computer interface design, especially provides possible way to improve online knowledge sharing by visual tool like icon. | From action icon to knowledge icon: Objective-oriented icon taxonomy in computer science |
S0141938215300111 | This paper presents a new bi-side gate driver integrated by indium-zinc-oxide thin film transistors (IZO TFTs). Our optimized operate method can achieve high speed performance by employing a lower duty ratio (25%) CK2 with its pulse located in the middle of the pulse of CK2L to fully use the bootstrapped high voltage of node Q. In addition, the size of devices is optimized by calculation and simulation, and the function of the proposed gate driver is predicted by the circuit simulation. Furthermore, the proposed gate driver with 20 stages is fabricated by the IZO TFTs process. It is shown that a 2.6μs width pulse with good noise-suppressed characteristic can be successfully output at the condition of R load =6kΩ and C load =150pF. The power consumption of the proposed gate driver with 20 stages is measured as 1mW. Hence, the proposed gate driver may be applied to the display of 4K resolution (4096×2160) at a frame rate of 120Hz. Moreover, there is a good stability for the proposed gate driver under 48h operation. | Design of high speed gate driver employing IZO TFTs |
S0141938215300135 | To study the interface effects on the device performance, we fabricated indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs) with a two-stack gate-insulator structure. The two-stack gate insulator was composed of a thick main insulator and a thin interfacial insulator; the main insulator determines the effective permittivity of the gate insulator, and the interfacial insulator regulates the gate/active interface properties. The a-IGZO TFTs had about 10cm2 V−1 s−1 field effect mobility (μ FE) values and 107–108 switching ratios. The dependences of μ FE and threshold voltage, V TH, on the channel width to length ratio were different according to the electron affinity, χ, of the interfacial insulator. The contact resistance between the source/drain electrode and the active layer, and the electron-injection barrier height from the active layer to the interfacial gate insulator layer could explain this finding. In this work, we successfully demonstrated the method to distinguish the interface-related phenomena from the insulator permittivity-related phenomena. | Analysis of the dependence of indium–gallium–zinc oxide thin-film transistor properties on the gate interface material using a two-stack gate-insulator structure |
S0141938215300147 | Blue color organic/polymeric light emitting diodes are very important because they can be used for tri-color display applications, fluorescence imaging, and exciting yellow phosphor for generating white light for general illumination. But the efficiency of blue organic/polymeric light emitting diodes is considerably low due to their large band gap that requires higher energy for effective emission. In this paper we report the enhancement in polyfluorene blue organic light emitting diodes with a polymer nano-composite hole transport layer. Blue light emitting diode based on polyfluorene as an emissive layer and poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate)–titanium dioxide nanocomposite as the hole transport layer were fabricated and studied. Different concentrations of titanium dioxide nanoparticles were doped in poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) in the hole transport layer and the performance of the devices were studied. Significant enhancement in the blue peak at 430nm of polyfluorene has been observed with increase in concentration of TiO2 nanoparticles in the hole transport layer. The turn on voltage of the device has also been found to improve significantly with the incorporation of titanium dioxide nanoparticles in the hole transport layer. The optimized concentration of titanium dioxide in the hole transport layer for most efficient device has been found to 15wt.%. | Efficiency enhancement in blue organic light emitting diodes with a composite hole transport layer based on poly(ethylenedioxythiophene):poly(styrenesulfonate) doped with TiO2 nanoparticles |
S0141938215300159 | It is a challenging task to improve the visual comfort of a stereoscopic 3D (S3D) image with satisfactory viewing experience. In this paper, we propose a visual comfort improvement scheme by adjusting zero-disparity plane (ZDP) for projection. The degree of visual discomfort is predicted by considering three factors: spatial frequency, disparity response, and visual attention. Then, the selection of an optimal ZDP is guided by the predicted visual discomfort map. Finally, the disparity ranges of the crossed and uncrossed disparities are automatically adjusted according to the ZDP as requirements. Experiment results show that the proposed scheme is effective in improving visual comfort while preserving the unchanged depth sensation. | Visual discomfort relaxation for stereoscopic 3D images by adjusting zero-disparity plane for projection |
S0141938215300160 | A new display concept for reproduction of high-luminance colors based on a liquid crystal display has been developed using a brighter backlight unit and color mapping algorithms. The new concept is able to display brighter colors close to a peak luminance of a display white than conventional displays so that realistic scene of brighter colors is better reproduced. It may also be one of the future display solutions needed to extend the color gamut in the direction of brighter colors, which is a principal limitation in conventional displays even in high-dynamic range display systems. With the new concept, an xvYCC- (extended-video YCbCr) compatible display can be easily realized. | New display concept for realistic reproduction of high-luminance colors |
S0141938215300172 | Data hiding, also known as information hiding, plays an important role in information security for various purposes. Reversible data hiding is a technique that allows distortion-free recovery of both the cover image and the secret information. In this paper, we propose a new, reversible data hiding scheme that is based on the Sudoku technique and can achieve higher embedding capacity. The proposed scheme allows embedding more secret bits into a pair of pixels while guaranteeing the good quality of the stego-image. The experimental results showed that the proposed scheme obtained higher embedding capacity than some other previous schemes. In addition, our proposed scheme maintained the good visual quality of the stego-image (i.e., PSNR>46dB), which outperforms some existing schemes. | A reversible data hiding scheme based on the Sudoku technique |
S0141938215300196 | Objective Visually induced motion sickness (VIMS) and increased postural sway are two adverse side effects that may occur when viewing motion stimuli. However, whether these effects are elevated to a greater extent when viewing stereoscopic 3D motion stimuli, compared to 2D stimuli on a TV screen, has not been investigated under controlled circumstances. Therefore this study aimed at investigating VIMS and postural sway before, during, and directly after viewing 2D and 3D motion stimuli, on a commonly available TV screen. Method 16 Participants were exposed to an aviation documentary shown in 2D and in 3D on separate occasions. Before, during, and after exposure, VIMS and postural sway were measured. VIMS was quantified by a rating scale giving a single number, and by a multi-symptom questionnaire that assessed multiple VIMS symptoms separately. Sway path length, standard deviations and short-range and long-range scaling components of the center of pressure were calculated as measures of postural sway. Results VIMS symptom severity, as obtained with the single rating scale, did not show a significant increase to either 2D or 3D exposure. The multi-symptom questionnaire did reveal significant increases in VIMS symptom severity to both 2D and 3D exposure. However, VIMS was not significantly more increased in case of 3D exposure compared to 2D exposure. All postural sway measures (sway path length, standard deviation in mediolateral and anteroposterior direction, as well as the short-range scaling components) increased significantly as a result of exposure. None of the postural sway measures was differentially affected to 3D as compared to 2D exposure. Conclusion Viewing 3D motion stimuli did not cause more serious VIMS symptoms, compared to viewing motion stimuli in 2D. We attribute this lack of difference to the fact that the 3D effects in this documentary were optimized for viewing in a cinema, the projection on the TV-screen thus causing quarantining of the visual input. The increase in postural sway, irrespective of image type, may reflect exploratory behavior, allowing the participant to gain more information about self-orientation with respect to the virtual environment. | Equally moved and not really sick from viewing 2D and 3D motion stimuli on a TV screen |
S0141938215300202 | A series of Eu3+-activated Li2Mg2(WO4)3 (LMW) materials were synthesized by high temperature solid state reactions. The phosphor can be effectively excited by 394nm near ultraviolet light and emit intense red light with high color purity. Prepared phosphors can be indexed to LMW with particular lyonsite structure. The occupation of Eu3+ in LMW is selective. Most of Eu3+ comes into 1A sites without inversion symmetry. The present research suggests that LMW is a suitable host for luminescence applications and Eu3+-activated LMW is a promising phosphor for phosphor-converted white light-emitting diodes. | Red phosphor Li2Mg2(WO4)3: Eu3+ with lyonsite structure for near ultraviolet light-emitting diodes |
S0141938215300238 | In this paper, a new data hiding method is proposed based on secret sharing scheme with the DNA exclusive or (DNA-XOR) operator for color images. The DNA-XOR secret sharing scheme uses a DNA-XOR truth table. Each input value of truth table is evaluated and according to that evaluation, highest PSNR (Peak Signal-to-Noise Ratio) value is selected for secret sharing. These selected values are embedded into cover image. Cover image is used as an encryption key in the proposed secret sharing process. In this study, the hidden data are divided into three secret shares and embedded into the red, green and blue channels of a cover image respectively. In here, the DNA-XOR operator has been firstly used as secret sharing operator in data hiding literature. Our proposed data hiding method was compared with previous methods. The comparison of these methods shows that our proposed method gives the most successful result. | A reversible data hiding algorithm based on probabilistic DNA-XOR secret sharing scheme for color images |
S0141938215300354 | Although visually impaired people are generally considered to be dependent and helpless people, they actually share the same characteristics as other people. Thanks to the Braille alphabet, which has been developed to reduce inequality of opportunity to minimum, their lives become a little bit easier. Besides Braille alphabet, there are many devices and software developed for visually impaired people. In this study, a readable, vocalized and refreshable Braille device, which can ease the lives of visually impaired people, has been developed. The results of the tests on this device with 20 visually-impaired people whose ages ranged between 5 and 15 and who do not know the Braille alphabet indicated the usability rate of this device to be 81.8%. The usability rate of the device was found to be 97.16% in the tests with 30 visually-impaired people whose ages ranged between 10 and 33 and who know the Braille alphabet. The durability test of the device indicated that Braille cells worked with 100% efficiency in the trials from 50 characters to 4000 characters. The device was superior both in terms of features and 35% cheaper compared to the ones available on the market. Besides, it was determined that USB connection transmitted data faster compared to the Bluetooth connection. | An interactive and multi-functional refreshable Braille device for the visually impaired |
S0141938215300391 | The development of mobile devices nowadays shows an increasing trend toward interacting with 3D digital content on a 2D touch screen. However, many issues regarding the appropriateness of the control mode require further exploration. The experimental design in this study designates displays of two sizes—five inches and seven inches—with three groups of hand gestures controlling the X-, Y-, and Z-axis, respectively. The three groups of gestures are compared in terms of how they interact with the 3D content. In the experiment, 30 adult research subjects twice completed a task that involved rotating three 3D immersive-heritage models. Their characteristics, completion time, subjective evaluation, and frequency of gesture change were measured and examined. The results from the experiment and the statistics from a two-way Analysis of Variance (ANOVA) indicate: (1) the display size and the task-completion time are inversely related. Under the effect of the Control–Display ratio, using a smaller display results in a shorter completion time while using a larger display results in a longer completion time; (2) tasks with obvious characteristics for the 3D objects require a shorter time to complete, but those with no obvious characteristics require more time; and (3) using familiar hand gestures leads to a shorter task-completion time, while using unfamiliar hand gestures leads to a longer completion time. The findings of this study show that the Control–Display ratio is an important factor that affects the operational performance of the 3D immersive-heritage model’s rotation tasks completed with hand gestures on small displays. In addition, adaptability and familiarity should be taken into consideration when introducing new hand gestures. Hence, the suggestions in this study constitute important guidelines for museums designing technology for the interaction between mobile devices and 3D immersive-heritage models. | The effects of screen size on rotating 3D contents using compound gestures on a mobile device |
S0141938215300421 | Electronic visual displays have shown a rapid technological evolution in the last two decades. With reference to the ergonomic requirements for video display terminal (VDT) workstations (ISO 9241), at an international level, attention is focused on the human–system interaction. With reference to visual ergonomics, the aim of this study is to assess luminance conditions through in-field measurements in order to evaluate: luminance and contrast ratios, luminance and contrast non-uniformities. The assessment was applied to widespread flat screen displays and repeated for fourteen combinations of Contrast–Brightness. The analysis carried out by the Authors shows the importance of realizing a simple and quick procedure to determine the performance levels of displays used in VDT workstations. The proposed assessment could be used as a practical tool for staff assigned to assess the risks arising from VDT use in the workplace within the Occupational Health and Safety Assessment Procedure. | Visual ergonomics of video-display-terminal workstations: Field measurements of luminance for various display settings |
S0141938215300433 | The phase behaviors of a blue-phase (BP) liquid crystal in a planar-aligned cell were investigated by means of temperature-dependent dielectric spectroscopy. With auxiliary observations of optical transmission spectra and birefringent textures, we found that the transition temperatures of two adjacent mesophases, including the cholesteric-to-BPI, the BPI-to-BPII, and the BPII-to-isotropic, can clearly be distinguished by the first and second derivatives of the real-part dielectric permittivity function to the temperature at a specific frequency. Furthermore, an attempt to evaluate the device performance of a polymer-stabilized BP, derived from the photopolymerization of two monomers (RM257 and TMPTA), was achieved with a new circuital design for the voltage-holding-ratio (VHR) measurement. Preliminary results of the VHRs of samples at 180Hz and their temperature dependence were obtained accordingly. | Dielectric characterization and voltage holding ratio of blue-phase cells |
S0141938215300445 | We report on the temperature dependence of dielectric properties of nematic liquid crystals impregnated with BaTiO3 (BTO) ferroelectric nanoparticles. The behavior of ion transport at low frequencies is discussed by means of dielectric spectroscopy, which allows the ionic concentration and the relaxation time of electrode polarization to be deduced. The experimental results imply that the ferroelectric nanoparticles can not only increase the traveling time of ions between two electrodes but also suppress the buildup of the electric double layers. Verified by the voltage holding ratio of cells containing various contents of BTO nanoparticles, it is obvious that doping BTO into liquid crystals is a low-cost and easy way to improve the device performance. | Temperature-dependent electrical and dielectric properties of nematic liquid crystals doped with ferroelectric particles |
S0141938215300457 | We present a simple and efficient way to improve the performance of the twisted nematic liquid crystal (LC) system by doping a small amount of n-alcohols. The LCs modified by n-hexanol demonstrates the optimum electro-optical properties of lower driving voltage and shorter response time. Our measurements indicate that the liquid dopant n-alcohols can be used to modify LCs for lowering zenithal anchoring energy relative to undoped LCs. Without the drawbacks of precipitation and aggregation that the nanoparticles could have, the method of doping n-alcohol liquids provides a more stable and reliable choice to apply in the various LC display systems. | The n-alcohols liquid doping effect on the twisted nematic liquid crystals |
S0141938215300470 | Modern interfaces increasingly rely on screens filled with digital text to display information to users. Previous research has shown that even relatively subtle differences in the design of the on-screen typeface can influence to-device glance time in a measurable and meaningful way (Reimer et al., 2014). Here we outline a methodology for rapidly and flexibly investigating the legibility of typefaces on digital screens in glance-like contexts, and apply this method to a comparison of 5 Simplified Chinese typefaces. We find that the legibility of the typefaces, measured as the minimum presentation time needed to read character strings accurately and respond to a yes/no lexical decision task, is sensitive to differences in the typeface’s design characteristics. The most legible typeface under study (“MT YingHei”) could be read 33.1% faster than the least legible typeface in this glance-induced context. A second study examined two different weights of the MT YingHei type family (medium and bold), as well as two contrast polarity (color) conditions to investigate how these variations impact legibility thresholds. Results indicate that bold weight text is easier to read in this enforced glance-like context, and that positive polarity text (black on white) is easier to read compared to white on black text under the lighting conditions considered. These results are discussed in terms of contextual factors that may mediate glance-reading behavior, as well as how type design interacts with the practical limitations of a moderate density pixel grid. | The effects of Chinese typeface design, stroke weight, and contrast polarity on glance based legibility |
S0141938215300482 | Large displays enable users to perform several tasks simultaneously. Under such circumstances, notification information provided through the concept of ambient displays plays a vital role in assisting users to switch among tasks. This paper presents the experimental results of a notification system design in the peripheral region of large displays. The aim is to provide guidance for notification information design by investigating detection and discrimination performance of human observers when visual notification information is presented away from the foveal region and viewed using peripheral vision. The proposed notification system was designed using an array of glyphs. Each glyph is a small gray square with a fixed size of 60×60 pixels. By changing the gray levels of adjacent glyphs dynamically, a glyph array presents a particular dynamic pattern. The experiments involved testing factors that comprised the visual angle, size and shape of glyph arrays, frequency of temporal modulation, phase shift of each pattern, and number of stimuli. The results show that glyph arrays are detected accurately if they are larger, even at wide viewing angles, and that the number of glyphs in a glyph array affects the performance more than the shapes of glyph arrays do. Furthermore, the discrimination performance is higher when both the frequency and phase are manipulated simultaneously (multidimensional design), compared with the case when each of these dimensions is varied separately (single-dimensional design). When the number of stimuli is set at 8, for example, users can maintain an accuracy rate of 70% for the multidimensional design, whereas the accuracy rate is only approximately 60% for the single-dimensional design. | Evaluation of detection and discrimination ability of peripheral vision on notification information based on large displays |
S0141938215300494 | In this paper, we proposed a novel method to embed a series of ternary secret data into a cover image based on an improved Least-Significant-Bit (LSB) scheme using the modulo three strategy. Our new method can hide two ternary numbers into each grayscale pixel, normally only modify the two LSBs of the pixel, while it may cause overflow/underflow and a carry/borrow. We solve these problems by adding 1 to the pixel or subtracting 1 from the pixel before embedding. The embedding capacity of our method can be 3.1699bpp. At the same time, the quality of the stego image of our new method also is better than traditional LSB scheme when the embedding capacity is greater than 3bpp with a Peak Signal-to-Noise Ratio (PSNR) greater than 37dB. Extensive experimental results indicated that our new method is capable of getting a higher PSNR than traditional LSB scheme when the embedding capacity is greater than 3bpp, and it has higher resistance ability against the chosen steganalysis algorithm when the embedding capacity is low. | An improved least-significant-bit substitution method using the modulo three strategy |
S0141938215300536 | The MoO3 doped N,N′-bis-(1-naphthyl)-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB:MoO3 in 2:1 mass ratio) and 4,4′-N,N′-dicarbazole-biphenyl (CBP:MoO3 in 2:1 mass ratio) as p-doped hole transport layers have been used in inverted organic light emitting diodes (IOLEDs). Compared to the NPB/20nm NPB:MoO3 structure, the NPB/10nm CBP:MoO3/10nm NPB:MoO3 structure showed increased device performance, mostly because the hole transport barrier from CBP:MoO3 to NPB was smaller than that from NPB:MoO3 to NPB; it also presented improved device performance than the NPB/20nm CBP:MoO3 structure, ascribed to the higher conductivity of NPB:MoO3 than that of CBP:MoO3. We provide a manageable way to unlock the merits of p-doped hole transport layers for markedly increasing the performance of IOLEDs. | Unlocking the potential of p-doped hole transport layers in inverted organic light emitting diodes |
S0141938215300561 | This paper presents an optimized color characterization model based on Radial Basis Functions (RBFs). The performance of the proposed model was tested on a number of different mobile devices and compared with the performance of other state of the art color characterization models. We compared the accuracy of models using the CIELAB color difference. Four different models were discussed in detail: Piecewise Linear Model Assuming Variation in Chromaticity, Polynomial regression, Artificial Neural Network, and proposed Radial Basis Function model. For training and evaluation of the models we measured a large number of color samples on various mobile device displays. Results have shown that our optimized RBF model has superior accuracy over other models with median color difference of 0.39. In addition, it has particularly good accuracy for colors on the boundary of device’s gamut with maximum color difference of 0.87, where other models shown unacceptably high (>10) color difference. | An optimized Radial Basis Function model for color characterization of a mobile device display |
S0141938216300026 | A new method is developed for the preparation of a transparent electrically conductive hybrid polymer films which maintain their electrical conductivity when subjected to deformation in two and three dimensions including bending, stretching and twisting. These films are made by a hybrid roll to roll (R2R) process where electrically conductive nanofibers are partially embedded in solution cast dielectric polymer films such as poly(methyl methacrylate) (PMMA), polyimide (PI) or polyurethanes (PU). Nanofibers partially embedded in films can be laser ablated to obtain in-plane anisotropic electrical conductivity created in the form of parallel conductive lines separated by non-conductive spaces on the film surface. The patterned films can be used for high resolution pixel addressable liquid crystal displays. There are several situations, such as wearable sensors, curved displays and advanced flexible OLED lightings, where elastic extensibility and/or permanent deformability are desired without significant loss of electrical conductivity. To satisfy this demand, the multifunctional films can be made elastic, thermally deformable with the judicious choice of materials comprising the nanofibers and the matrix they are embedded in. The multifunctional transparent conductive films are easily manufactured through a low-cost continuous hybrid roll to roll process. Furthermore, they can be used in future displays, solar cells, wearable electronics and skin attached sensors requiring flexibility as well as stretchability and more desirably subsequent recovery after cessation of stress and strains without any loss of electrical conductivity. | Flexible, stretchable, transparent and electrically conductive polymer films via a hybrid electrospinning and solution casting process: In-plane anisotropic conductivity for electro-optical applications |
S0141938216300087 | The objective of this study is to put forward a new non-contact resistance measurement method for repeating bending tests of transparent electrodes deposited on flexible display substrates. The study utilizes a terahertz time domain spectroscopy (THz-TDS) method to measure electrical properties of flexible polyethylene terephthalate/indium tin oxide samples up to 20,000 bending times. In addition, this study utilizes THz-TDS method to measure electrical characteristics of flexible substrates with hard-coat films. Accordingly, the percentage errors of measured sheet resistances based on THz-TDS method are less than or equal to 5.5% for comparison with a contact type four-point probe method or our previously reported flexible characteristic inspection system method. The values show a reasonable agreement with contact-mode sheet resistance measurements. Therefore, the electrical properties of thin films are measured offline or online easily by using this method. | Non-contact resistance measurement of transparent electrodes deposited on flexible display substrates under repetitive bending test by terahertz time domain spectroscopy |
S0141938216300166 | Three-dimensional (3-D) images are perceived as images that float in front of the screens of 3-D displays. Users should be able to interact with these images instantaneously and accurately in applications where their bodies actually seen by them interact with the images. However, conventional techniques using just binocular disparity are too slow and inaccurate. Therefore, we propose a new technique where the visually perceived positions of images are obtained from the body movements of users. The feasibility of this technique was evaluated in an experiment using the positions obtained from users as they reached out to touch the images. These positions were closer to the visually perceived positions of the images than those calculated from binocular disparity. These findings demonstrate the feasibility of the proposed technique for 3-D interactive applications. | New technique of obtaining visually perceived positions of 3-D images using movements of users’ bodies |
S0141938216300178 | In the product emotional design era, the website homepage design, especially the aesthetic design, has become a key factor that influences users’ first impressions, attitudes and behaviors. Based on the Stimulus-Organism-Response (S-O-R) theory, the current study examines the mechanism through which the aesthetic design of a comprehensive job-hunting website homepage affects users’ satisfaction. Emotion and perceived ease of use were used to describe users’ internal evaluation to the homepage (i.e. organism). The Structural Equation Modeling method was used to test the proposed hypotheses. The empirical evidence shows that aesthetic formality does not have a significant impact on positive arousal, but it has positively influences on energetic arousal through its impact on aesthetic appeal. The other hypotheses proposed in this study are all been supported. The additional results, i.e. the effects of three key design elements on homepage aesthetics, are found. The aim of this study was to provide practical recommendation in the establishment of a pattern of webpage aesthetics that influences users’ satisfaction. | How homepage aesthetic design influences users’ satisfaction: Evidence from China |
S0141938216300312 | The impact of aberration on the speckle suppression efficiency is investigated in a laser projector system containing a moving diffractive optical element (DOE). The results of a qualitative analysis based on the number of diffraction orders passed through the optical system are presented, along with a quantitative analysis built upon the Fresnel approximation and the thin lens model. It is shown that the speckle contrast in the paraxial area of the screen is practically insensitive to aberrations — limited to a few percent at most, due to the change in angle between diffraction orders. However, the speckle contrast in peripheral areas changes stepwise if aberrations change the number of diffraction orders that illuminate the area. | Impact of aberrations on speckle suppression efficiency on moving a DOE inside the optical system |
S0142061513002585 | Conventionally monitoring operating conditions of a power transmission line is accomplished by periodic inspections along this line. This monitoring allows corrective maintenance by finding faults during the inspection. But in more efficient maintenance, predictive techniques that are characterized by real-time monitoring should be employed. Such predictive techniques allow for verifying the working status of the line by using normal working models to detect faults and fault models for diagnosis. This paper presents a study that used a mathematical model appropriate for application to predictive maintenance of transmission line segments at low cost, without the need for sensors distributed along the line, and presenting a new indicator of transmission line operation conditions. By tracking the leakage current of transmission lines, this model allows for estimating the current line insulation status. Once the current line insulation status is known, it is possible to compare it against other future status and verify the progress of the insulation conditions of that line. The model uses a new indicator, called MCHO, which can detect and diagnose both normal and abnormal operating conditions of a power transmission line. This new indicator is the capacitance of the harmonic frequencies of the transmission line leakage current. The model was validated through measurements obtained on a stretch of transmission line. | MCHO – A new indicator for insulation conditions in transmission lines |
S0142061513002676 | In this paper, an interleaved step-up converter with a single-capacitor snubber for PV energy conversion applications is proposed. The step-up converter adopts two sets of boost converters with an interleaved fashion and coupled-inductor technology to reduce output ripple current and increase output power level. To achieve higher conversion efficiency and reduce switching losses of the proposed converter, a lossless single-capacitor turn-off snubber is introduced. Therefore, the conversion efficiency can be increased significantly. In order to draw the maximum power from the PV arrays, a perturbation-and-observation method and a microcontroller are associated to implement maximum power point tracking (MPPT) algorithm and power regulating scheme. Finally, a prototype of a soft-switching interleaved soft-switching boost converter with coupled inductors has been built and implemented. Experimental results have obtained to verify the performance and feasibility of the proposed converter for PV arrays applications. | Interleaved step-up converter with a single-capacitor snubber for PV energy conversion applications |
S0142061513003517 | Gravitational search algorithm (GSA) is based on law of gravity and the interaction between masses. In GSA, searcher agents are collection of masses and their interactions are based on Newtonian laws of gravity and motion. In this paper, to further improve the optimization performance of GSA, opposition-based learning is employed in opposition-based gravitational search algorithm (OGSA) for population initialization and also for generation jumping. In the present work, OGSA is applied for the solution of optimal reactive power dispatch (ORPD) of power systems. Traditionally, ORPD is defined as the minimization of active power transmission losses by controlling a number of control variables. ORPD is formulated as a non-linear constrained optimization problem with continuous and discrete variables. In this work, OGSA is used to find the settings of control variables such as generator voltages, tap positions of tap changing transformers and amount of reactive compensation to optimize certain objectives. The study is implemented on IEEE 30-, 57- and 118-bus test power systems with different objectives that reflect minimization of either active power loss or that of total voltage deviation or improvement of voltage stability index. The obtained results are compared to those yielded by the other evolutionary optimization techniques surfaced in the recent state-of-the-art literature including basic GSA. The results presented in this paper demonstrate the potential of the proposed approach and show its effectiveness and robustness for solving ORPD problems of power systems. | Solution of reactive power dispatch of power systems by an opposition-based gravitational search algorithm |
S0142061514000027 | During the last years wind power has emerged as one of the most important sources in the power generation share. Due to stringent Grid Code requirements, wind power plants (WPPs) should provide ancillary services such as fault ride-through and damping of power system oscillations to resemble conventional generation. Through an adequate selection of input–output signal pairs, WPPs can be effectively used to provide electromechanical oscillations damping. In this paper, different analysis techniques considering both controllability and observability measures and input–output interactions are compared and critically examined. Recommendations are drawn to select the best signal pairs available from WPPs to contribute to power oscillations damping. Control system design approaches including single-input single-output and multivariable control are considered. The recommendation of analysis techniques is justified through the tools usage in a test system including a WPP. | Input–output signal selection for damping of power system oscillations using wind power plants |
S0142061514003743 | This survey paper is an excerpt of a more comprehensive study on Smart Grid (SG) and the role of Advanced Metering Infrastructure (AMI) in SG. The survey was carried out as part of a feasibility study for creation of a Net-Zero community in a city in Ontario, Canada. SG is not a single technology; rather it is a combination of different areas of engineering, communication and management. This paper introduces AMI technology and its current status, as the foundation of SG, which is responsible for collecting all the data and information from loads and consumers. AMI is also responsible for implementing control signals and commands to perform necessary control actions as well as Demand Side Management (DSM). In this paper we introduce SG and its features, establish the relation between SG and AMI, explain the three main subsystems of AMI and discuss related security issues. | A survey on Advanced Metering Infrastructure |
S0142061514004815 | A power outage brings in economic losses for both the customers and the utilities. Studying these unwanted events and making solid predictions about the outcomes of the interruptions has been an attractive area of interest for the researchers for the last couple of decades. By making use of a customer survey study conducted in Finland, this paper benefits from both the reported cost data collected from customers and from the analytical data that are available and then presents a new hybrid approach to estimate the customer interruption costs of service sector customer segment. Making use of Value Added information of the customers is a common practice for the cost normalization purposes. This paper verifies the approach by comparing the findings of the customer survey and the econometric model suggested here. This study is a unique source in terms of providing a reliable, easy to apply, and a straightforward model for calculating the economic impacts of power outages. | Interruption costs of service sector electricity customers, a hybrid approach |
S0142061514005869 | This paper proposes a three-phase four-leg voltage sourced inverter (VSI) based load unbalance compensator (LUC) including its control algorithm, which is a component of a microgrid. The purpose of proposed three-phase four-leg VSI based LUC is to improve power quality of the standalone microgrid. Power quality of the microgrid which was installed in Mara-island, Korea is analyzed using a real operational data. In this work, the microgrid in Mara-island which includes a photovoltaic power generation system, a diesel generator, a battery energy storage system, and a power management system is modeled in PSCAD/EMTDC, and proposed three-phase four-leg VSI based LUC is also modeled and applies to the modeled microgrid. Power flow and stability of the modeled microgrid with the LUC is analyzed under variable irradiance and unbalance loads. The results show that the proposed LUC helps to improve stability of the stand-alone microgrid. The proposed three-phase four-leg VSI based LUC and its control algorithm can be effectively utilized to the stand alone microgrid which has large unbalance loads. | A novel three-phase four-leg inverter based load unbalance compensator for stand-alone microgrid |
S0142061514007686 | Evidence shows that a small number of line contingencies in power systems may cause a large-scale blackout due to the effects of cascading failures. With the development of new technologies and the growing number of heterogeneous participants, a modern/smart grid should be able to self-heal its internal disturbances by continually performing self-assessment to deter, detect, respond to and restore from unpredictable contingencies. Along this line, this research focuses on the problem of how to prevent the occurrence of cascading failures through load shedding by considering heterogeneous shedding costs of grid participants. A fair load-shedding algorithm is proposed to solve the problem in a decentralized manner, where a load-shedding participant need only monitor its own operational status and interact with its neighboring participants. Using an embedded feedback mechanism, the fair load-shedding algorithm can determine a marginal compensation price for each load-shedding participant in real time based on the proportional fairness criterion, without knowing the shedding costs of the participants. Such fairly determined compensations can help motivate loaders/generators to actively participate in the load shedding in the face of internal disturbances. Finally, the properties of the load-shedding algorithm are evaluated by carrying out an experimental study on the standard IEEE 30 bus system. The study will offer new insights into emergency planning and design improvement of self-healing smart grids. | Decentralized control and fair load-shedding compensations to prevent cascading failures in a smart grid |
S0142061515003324 | The increased number of renewable power plants pose threat to power system balance. Their intermittent nature makes it very difficult to predict power output, thus either additional reserve power plants or new storage and control technologies are required. Traditional spinning reserve cannot fully compensate sudden changes in renewable energy power generation. Using new storage technologies such as flow batteries, it is feasible to balance the variations in power and voltage within very short period of time. This paper summarises the controlled use of hybrid flow battery, thermal and hydro power plant system, to support wind power plants to reach near perfect balance, i.e. make the total power output as close as possible to the predicted value. It also investigates the possibility of such technology to take part in the balance of the Lithuanian power system. A dynamic model of flow battery is demonstrated where it evaluates the main parameters such as power, energy, reaction time and efficiency. The required battery size is tested based on range of thermal and hydro power plant reaction times. This work suggests that power and energy of a reasonable size flow battery is sufficient to correct the load and wind power imbalance. | Hybrid wind power balance control strategy using thermal power, hydro power and flow batteries |
S0164121213002641 | This paper presents an approach for the automated debugging of reactive and concurrent Java programs, combining model checking and runtime monitoring. Runtime monitoring is used to transform the Java execution traces into the input for the model checker, the purpose of which is twofold. First, it checks these execution traces against properties written in linear temporal logic (LTL), which represent desirable or undesirable behaviors. Second, it produces several execution traces for a single Java program by generating test inputs and exploring different schedulings in multithreaded programs. As state explosion is the main drawback to model checking, we propose two abstraction approaches to reduce the memory requirements when storing Java states. We also present the formal framework to clarify which kinds of LTL safety and liveness formulas can be correctly analysed with each abstraction for both finite and infinite program executions. A major advantage of our approach comes from the model checker, which stores the trace of each failed execution, allowing the programmer to replay these executions to locate the bugs. Our current implementation, the tool TJT, uses Spin as the model checker and the Java Debug Interface (JDI) for runtime monitoring. TJT is presented as an Eclipse plug-in and it has been successfully applied to debug complex public Java programs. | Using SPIN for automated debugging of infinite executions of Java programs |
S0164121213002744 | Many organisations are dependent upon long-term sustainable software systems and associated communities. In this paper we consider long-term sustainability of Open Source software communities in Open Source software projects involving a fork. There is currently a lack of studies in the literature that address how specific Open Source software communities are affected by a fork. We report from a study aiming to investigate the developer community around the LibreOffice project, which is a fork from the OpenOffice.org project. In so doing, our analysis also covers the OpenOffice.org project and the related Apache OpenOffice project. The results strongly suggest a long-term sustainable LibreOffice community and that there are no signs of stagnation in the LibreOffice project 33 months after the fork. Our analysis provides details on developer communities for the LibreOffice and Apache OpenOffice projects and specifically concerning how they have evolved from the OpenOffice.org community with respect to project activity, developer commitment, and retention of committers over time. Further, we present results from an analysis of first hand experiences from contributors in the LibreOffice community. Findings from our analysis show that Open Source software communities can outlive Open Source software projects and that LibreOffice is perceived by its community as supportive, diversified, and independent. The study contributes new insights concerning challenges related to long-term sustainability of Open Source software communities. | Sustainability of Open Source software communities beyond a fork: How and why has the LibreOffice project evolved? |
S0164121214001381 | Numerous component models have been proposed in the literature, a testimony of a subject domain rich with technical and scientific challenges, and considerable potential. Unfortunately however, the reported level of adoption has been comparatively low. Where successes were had, they were largely facilitated by the manifest endorsement, where not the mandate, by relevant stakeholders, either internal to the industrial adopter or with authority over the application domain. The work presented in this paper stems from a comprehensive initiative taken by the European Space Agency (ESA) and its industrial suppliers. This initiative also enjoyed significant synergy with interests shown for similar goals by the telecommunications and railways domain, thanks to the interaction between two parallel project frameworks. The ESA effort aimed at favouring the adoption of a software reference architecture across its software supply chain. The center of that strategy revolves around a component model and the software development process that builds on it. This paper presents the rationale, the design and implementation choices made in their conception, as well as the feedback obtained from a number of industrial case studies that assessed them. | A component-based process with separation of concerns for the development of embedded real-time software systems |
S0164121214002702 | This paper proposes an architecture and associated methodology to separate front end UI concerns from back end coding concerns to improve the platform flexibility, shorten the development time, and increase the productivity of developers. Typical UI development is heavily dependent upon the underlying platform, framework, or tool used to create it, which results in a number of problems. We took a separation-based UI architecture and modified it with a domain specific language to support the independence of UI creation thereby resolving some of the aforementioned problems. A methodology incorporating this architecture into the development process is proposed. A climate science application was created to verify the validity of the methodology using modern practices of UX, DSLs, code generation, and model-driven engineering. Analyzing related work provides an overview of other methods similar to our method. Subsequently we evaluate the climate science application, conclude, and detail future work. | A separation-based UI architecture with a DSL for role specialization |
S0164121215000151 | Root cause analysis (RCA) is a recommended practice in retrospectives and cause–effect diagram (CED) is a commonly recommended technique for RCA. Our objective is to evaluate whether CED improves the outcome and perceived utility of RCA. We conducted a controlled experiment with 11 student software project teams by using a single factor paired design resulting in a total of 22 experimental units. Two visualization techniques of underlying causes were compared: CED and a structural list of causes. We used the output of RCA, questionnaires, and group interviews to compare the two techniques. In our results, CED increased the total number of detected causes. CED also increased the links between causes, thus, suggesting more structured analysis of problems. Furthermore, the participants perceived that CED improved organizing and outlining the detected causes. The implication of our results is that using CED in the RCA of retrospectives is recommended, yet, not mandatory as the groups also performed well with the structural list. In addition to increased number of detected causes, CED is visually more attractive and preferred by retrospective participants, even though it is somewhat harder to read and requires specific software tools. | Diagrams or structural lists in software project retrospectives – An experimental comparison |
S0164121215000680 | Test case prioritization assigns the execution priorities of the test cases in a given test suite. Many existing test case prioritization techniques assume the full-fledged availability of code coverage data, fault history, or test specification, which are seldom well-maintained in real-world software development projects. This paper proposes a novel family of input-based local-beam-search adaptive-randomized techniques. They make adaptive tree-based randomized explorations with a randomized candidate test set strategy to even out the search space explorations among the branches of the exploration trees constructed by the test inputs in the test suite. We report a validation experiment on a suite of four medium-size benchmarks. The results show that our techniques achieve either higher APFD values than or the same mean APFD values as the existing code-coverage-based greedy or search-based prioritization techniques, including Genetic, Greedy and ART, in both our controlled experiment and case study. Our techniques are also significantly more efficient than the Genetic and Greedy, but are less efficient than ART. | Input-based adaptive randomized test case prioritization: A local beam search approach |
S0164121215001740 | There exists no generally accepted theory in software engineering, and at the same time a scientific discipline needs theories. Some laws, hypotheses and conjectures exist, but yet no generally accepted theory. Several researchers and initiatives emphasize the need for theory in the discipline. The objective of this paper is to formulate a theory of software engineering. The theory is generated from empirical observations of industry practice, including several case studies and many years of experience in working closely between academia and industry. The theory captures the balancing of three different intellectual capitals: human, social and organizational capitals, respectively. The theory is formulated using a method for building theories in software engineering. It results in a theory where the relationships between the three different intellectual capitals are explored and explained. The theory is illustrated based on an industrial case study, where it is shown how decisions made in industry practice are explainable with the formulated theory, and the consequences of the decisions are made explicit. Based on the positive results, it is concluded that the theory may have a good explanatory power, although more evaluations are needed. | A general theory of software engineering: Balancing human, social and organizational capitals |
S0164121215001818 | Coping with evolution in automated production systems implies a cross-disciplinary challenge along the system's life-cycle for variant-rich systems of high complexity. The authors from computer science and automation provide an interdisciplinary survey on challenges and state of the art in evolution of automated production systems. Selected challenges are illustrated on the case of a simple pick and place unit. In the first part of the paper, we discuss the development process of automated production systems as well as the different type of evolutions during the system's life-cycle on the case of a pick and place unit. In the second part, we survey the challenges associated with evolution in the different development phases and a couple of cross-cutting areas and review existing approaches addressing the challenges. We close with summarizing future research directions to address the challenges of evolution in automated production systems. | Evolution of software in automated production systems: Challenges and research directions |
S0164121215001855 | Computing paradigms have shifted towards highly parallel processing and massive replication of data. This entails the efficient distribution of requests and the synchronization of results provided to users. Guaranteeing SLAs requires the ability to evaluate the performance of such systems while taking the effect of non-parallel workloads into consideration. This can be achieved with performance models that are able to represent both parallel and sequential workloads. This paper presents a product-form stochastic Petri-net approximation of fork-join queueing networks with interfering requests. We derive the necessary conditions that guarantee the accuracy of the approximations and verify this through examples in comparison to simulation. We apply these approximate models to the performance evaluation of replication in NoSQL cloud datastores and illustrate the composition of large models from smaller models, thus facilitating the ability to model a range of deployment scenarios. We show the efficiency of our solution method, which finds the product-form solution of the models without the representation of the state-space of the underlying CTMC. | Approximating closed fork-join queueing networks using product-form stochastic Petri-nets |
S0164121215002010 | Having a large number of applications in the marketplace is considered a critical success factor for software ecosystems. The number of applications has been claimed to determine which ecosystems holds the greatest competitive advantage and will eventually dominate the market. This paper investigates the influence of developer multi-homing (i.e., participating in more than one ecosystem) in three leading mobile application ecosystems. Our results show that when regarded as a whole, mobile application ecosystems are single-homing markets. The results further show that 3% of all developers generate more than 80% of installed applications and that multi-homing is common among these developers. Finally, we demonstrate that the most installed content actually comprises only a small number of the potential value propositions. The results thus imply that attracting and maintaining developers of superstar applications is more critical for the survival of a mobile application ecosystem than the overall number of developers and applications. Hence, the mobile ecosystem is unlikely to become a monopoly. Since exclusive contracts between application developers and mobile application ecosystems are rare, multi-homing is a viable component of risk management and a publishing strategy. The study advances the theoretical understanding of the influence of multi-homing on competition in software ecosystems. | The influence of developer multi-homing on competition between software ecosystems |
S0165168413003307 | Video transcoding is a legitimate operation widely used to modify video format in order to access the video content in the end-user's devices, which may have some limitations in the spatial and temporal resolutions, bit-rate and video coding standards. In many previous watermarking algorithms the embedded watermark is not able to survive video transcoding, because this operation is a combination of some aggressive attacks, especially when lower bit-rate coding is required in the target device. As a consequence of the transcoding operation, the embedded watermark may be lost. This paper proposes a robust video watermarking scheme against video transcoding performed on base-band domain. In order to obtain the watermark robustness against video transcoding, four criteria based on Human Visual System (HVS) are employed to embed a sufficiently robust watermark while preserving its imperceptibility. The quantization index modulation (QIM) algorithm is used to embed and detect the watermark in 2D-Discrete Cosine Transform (2D-DCT) domain. The watermark imperceptibility is evaluated by conventional peak signal to noise ratio (PSNR) and structural similarity index (SSIM), obtaining sufficiently good visual quality. Computer simulation results show the watermark robustness against video transcoding as well as common signal processing operations and intentional attacks for video sequences. | Transcoding resilient video watermarking scheme based on spatio-temporal HVS and DCT |
S0165168414000644 | In this paper, we design and analyze a Newton-like blind equalization algorithm for the APSK system. Specifically, we exploit the principle of minimum entropy deconvolution and derive a blind equalization cost function for APSK signals and optimize it using Newton׳s method. We study and evaluate the steady-state excess mean square error performance of the proposed algorithm using the concept of energy conservation. Numerical results depict a significant performance enhancement for the proposed scheme over well established blind equalization algorithms. Further, the analytical excess mean square error of the proposed algorithm is verified with computer simulations and is found to be in good conformation. | Newton-like minimum entropy equalization algorithm for APSK systems |
S0165168414000814 | Mobile device localization in wireless sensor networks is a challenging task. It has already been addressed when the WiFi propagation maps of the access points are modeled deterministically or estimated using an offline human training calibration. However, these techniques do not take into account the environmental dynamics. In this paper, the maps are assumed to be made of an average indoor propagation model combined with a perturbation field which represents the influence of the environment. This perturbation field is embedded with a distribution describing the prior knowledge about the environmental influence. The device is localized with Sequential Monte Carlo methods and relies on the estimation of the propagation maps. This inference task is performed online, using the observations sequentially, with a new online Expectation Maximization based algorithm. The performance of the algorithm is illustrated with Monte Carlo experiments using both simulated data and a true data set. | Simultaneous localization and mapping in wireless sensor networks |
S0165168414001054 | In this paper, we propose a musical-noise-free blind speech extraction method using a microphone array for application to nonstationary noise. In our previous study, it was found that optimized iterative spectral subtraction (SS) results in speech enhancement with almost no musical noise generation, but this method is valid only for stationary noise. The proposed method consists of iterative blind dynamic noise estimation by, e.g., independent component analysis (ICA) or multichannel Wiener filtering, and musical-noise-free speech extraction by modified iterative SS, where multiple iterative SS is applied to each channel while maintaining the multichannel property reused for the dynamic noise estimators. Also, in relation to the proposed method, we discuss the justification of applying ICA to signals nonlinearly distorted by SS. From objective and subjective evaluations simulating a real-world hands-free speech communication system, we reveal that the proposed method outperforms the conventional methods. | Musical-noise-free blind speech extraction integrating microphone array and iterative spectral subtraction |
S0165168414002953 | Structured sparsity approaches have recently received much attention in the statistics, machine learning, and signal processing communities. A common strategy is to exploit or assume prior information about structural dependencies inherent in the data; the solution is encouraged to behave as such by the inclusion of an appropriate regularisation term which enforces structured sparsity constraints over sub-groups of data. An important variant of this idea considers the tree-like dependency structures often apparent in wavelet decompositions. However, both the constituent groups and their associated weights in the regularisation term are typically defined a priori. We here introduce an adaptive wavelet denoising framework whereby a sparsity-inducing regulariser is modified based on information extracted from the signal itself. In particular, we use the same wavelet decomposition to detect the location of salient features in the signal, such as jumps or sharp bumps. Given these locations, the weights in the regulariser associated to the groups of coefficients that cover these time locations are modified in order to favour retention of those coefficients. Denoising experiments show that, not only does the adaptive method preserve the salient features better than the non-adaptive constraints, but it also delivers significantly better shrinkage over the signal as a whole. | Wavelet shrinkage using adaptive structured sparsity constraints |
S0165168414003818 | Human motion denoising is an indispensable step of data preprocessing for many motion data based applications. In this paper, we propose a data-driven based human motion denoising method that sparsely selects the most correlated subset of motion bases for clean motion reconstruction. Meanwhile, it takes the statistic property of two common noises, i.e., Gaussian noise and outliers, into account in deriving the objective functions. In particular, our method firstly divides each human pose into five partitions termed as poselets to gain a much fine-grained pose representation. Then, these poselets are reorganized into multiple overlapped poselet groups using a lagged window moving across the entire motion sequence to preserve the embedded spatial–temporal motion patterns. Afterward, five compacted and representative motion dictionaries are constructed in parallel by means of fast K-SVD in the training phase; they are used to remove the noise and outliers from noisy motion sequences in the testing phase by solving ℓ1-minimization problems. Extensive experiments show that our method outperforms its competitors. More importantly, compared with other data-driven based method, our method does not need to specifically choose the training data, it can be more easily applied to real-world applications. | Sparse motion bases selection for human motion denoising |
S0165168414003855 | We present a novel unsupervised fall detection system that employs the collected acoustic signals (footstep sound signals) from an elderly person׳s normal activities to construct a data description model to distinguish falls from non-falls. The measured acoustic signals are initially processed with a source separation (SS) technique to remove the possible interferences from other background sound sources. Mel-frequency cepstral coefficient (MFCC) features are next extracted from the processed signals and used to construct a data description model based on a one class support vector machine (OCSVM) method, which is finally applied to distinguish fall from non-fall sounds. Experiments on a recorded dataset confirm that our proposed fall detection system can achieve better performance, especially with high level of interference from other sound sources, as compared with existing single microphone based methods. | An unsupervised acoustic fall detection system using source separation for sound interference suppression |
S0165168414003971 | The analysis of the stability and numerical simulation of Costas loop circuits for high-frequency signals is a challenging task. The problem lies in the fact that it is necessary to simultaneously observe very fast time scale of the input signals and slow time scale of phase difference between the input signals. To overcome this difficult situation it is possible, following the approach presented in the classical works of Gardner and Viterbi, to construct a mathematical model of Costas loop, in which only slow time change of signal׳s phases and frequencies is considered. Such a construction, in turn, requires the computation of phase detector characteristic, depending on the waveforms of the considered signals. While for the stability analysis of the loop near the locked state (local stability) it is usually sufficient to consider the linear approximation of phase detector characteristic near zero phase error, the global analysis (stability in the large) cannot be accomplished using simple linear models. The present paper is devoted to the rigorous construction of nonlinear dynamical model of classical Costas loop, which allows one to apply numerical simulation and analytical methods (various modifications of absolute stability criteria for systems with cylindrical phase space) for the effective analysis of stability in the large. Here a general approach to the analytical computation of phase detector characteristic of classical Costas loop for periodic non-sinusoidal signal waveforms is suggested. The classical ideas of the loop analysis in the signal׳s phase space are developed and rigorously justified. Effective analytical and numerical approaches for the nonlinear analysis of the mathematical model of classical Costas loop in the signal׳s phase space are discussed. | Nonlinear dynamical model of Costas loop and an approach to the analysis of its stability in the large |
S0165168414004368 | In this paper, we propose a novel method for the blind compensation of drift for the asynchronous recording of an ad hoc microphone array. Digital signals simultaneously observed by different recording devices have drift of the time differences between the observation channels because of the sampling frequency mismatch among the devices. On the basis of a model in which the time difference is constant within each short time frame but varies in proportion to the central time of the frame, the effect of the sampling frequency mismatch can be compensated in the short-time Fourier transform (STFT) domain by a linear phase shift. By assuming that the sources are motionless and have stationary amplitudes, the observation is regarded as being stationary when drift does not occur. Thus, we formulate a likelihood to evaluate the stationarity in the STFT domain to evaluate the compensation of drift. The maximum likelihood estimation is obtained effectively by a golden section search. Using the estimated parameters, we compensate the drift by STFT analysis with a noninteger frame shift. The effectiveness of the proposed blind drift compensation method is evaluated in an experiment in which artificial drift is generated. | Blind compensation of interchannel sampling frequency mismatch for ad hoc microphone array based on maximum likelihood estimation |
S0165168414004848 | Multimodulus algorithms (MMA) based adaptive blind equalizers mitigate inter-symbol interference in a digital communication system by minimizing dispersion in the quadrature components of the equalized sequence in a decoupled manner, i.e., the in-phase and quadrature components of the equalized sequence are used to minimize dispersion in the respective components of the received signal. These unsupervised equalizers are mostly incorporated in bandwidth-efficient digital receivers (wired, wireless or optical) which rely on quadrature amplitude modulation based signaling. These equalizers are equipped with nonlinear error-functions in their update expressions which makes it a challenging task to evaluate analytically their steady-state performance. However, exploiting variance relation theorem, researchers have recently been able to report approximate expressions for steady-state excess mean square error (EMSE) of such equalizers for noiseless but interfering environment. In this work, in contrast to existing results, we present exact steady-state tracking analysis of two multimodulus equalizers in a non-stationary environment. Specifically, we evaluate expressions for steady-state EMSE of two equalizers, namely the MMA2-2 and the βMMA. The accuracy of the derived analytical results is validated using different set experiments and found in close agreement. | Steady-state performance of multimodulus blind equalizers |
S0165168414005520 | Human motion retrieval plays an important role in many motion data based applications. In the past, many researchers tended to use a single type of visual feature as data representation. Because different visual feature describes different aspects about motion data, and they have dissimilar discriminative power with respect to one particular class of human motion, it led to poor retrieval performance. Thus, it would be beneficial to combine multiple visual features together for motion data representation. In this article, we present an Adaptive Multi-view Feature Selection (AMFS) method for human motion retrieval. Specifically, we first use a local linear regression model to automatically learn multiple view-based Laplacian graphs for preserving the local geometric structure of motion data. Then, these graphs are combined together with a non-negative view-weight vector to exploit the complementary information between different features. Finally, in order to discard the redundant and irrelevant feature components from the original high-dimensional feature representation, we formulate the objective function of AMFS as a general trace ratio optimization problem, and design an effective algorithm to solve the corresponding optimization problem. Extensive experiments on two public human motion database, i.e., HDM05 and MSR Action3D, demonstrate the effectiveness of the proposed AMFS over the state-of-art methods for motion data retrieval. The scalability with large motion dataset, and insensitivity with the algorithm parameters, make our method can be widely used in real-world applications. | Adaptive multi-view feature selection for human motion retrieval |
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