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Tea for Bedtime - A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
Some people may consider sleep as a setback or an unnecessary delay in their plans. However, even if you are terribly busy, taking enough time to sleep can literally save your day and make you more productive. Either if you’re looking for productivity or some time to relax, sleep is one of the most important activities in mammals and the majority of living beings.
But what happens during sleep, why is it important, and why are you having so much trouble getting asleep?
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
About Sleep & Sleep Problems
Sleep has been on the scope for years. Philosophers and scientists have made serious efforts to understand this activity, and more recently, neuroscientists have developed modern ways to study the brain of people when they sleep.
Many questions are still unanswered, but we do know that sleep is vital for neuronal recovery. It supports nervous activity, reorganizes neurons, repairs neuronal damage, and clears the brain from metabolic waste. Thus, it is fundamental if you want to learn, memorize, and keep on living (1).
You have probably experienced how a sleepless night makes it difficult to concentrate, gives you a feeling of drowsiness, and causes irritability. But there is also a clinical problem called “chronic partial sleep loss,” which is more common than insomnia and has similar consequences on the long-term (2).
If you are having insomniac, partially sleepless nights, or feel you’re not having enough resting hours at night, you might feel better by applying a few recommendations. We will break them down into three categories:
• Sleep rituals and sleep hygiene
• Drugs and natural treatment
• Easy lifestyle changes to follow
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
The Importance of Bedtime Rituals
Men are creatures of habit, and that includes our sleeping hours. As we grow older, our parents try to instill the habit of going to sleep early, and some of them used bedtime stories after tucking in and dimming the lights. The elements of the sleep ritual are different, but the majority of us slept better after listening to stories or songs we were used to listening around that time.
Even as an adult, it is possible to create sleep rituals that prepare the mind and tell your unconscious self it is bedtime. The ideal timing to implement these rituals is around one hour before your sleep time, and there are several options to choose from:
• Take a relaxing bath: In scientific research, the term is “water-based passive body heating.” According to studies, taking a relaxing bath or shower for 10 minutes, scheduled 1 hour before bedtime improves our sleep quality (3).
• Dim the lights: By dimming the lights, we are stimulating our body to secrete melatonin, a substance that improves sleep and helps us achieve a long deep sleep (REM sleep) (4).
• Turn off your devices: It is one of the best recommendations to teenagers and should be followed around one hour before sleep (5).
• Get a massage: A massage helps you relax, especially when performed by expert hands. This technique may reduce the time you need to get asleep (6).
• Try meditation: Meditation is one of the most widely researched tools for stress and anxiety, and it is beneficial to increase sleep quality and quantity (7).
• Use essential oils: Certain scents such as lavender help us manage anxiety, feel more relaxed, and improve the quality of sleep (8).
• Read a printed book: A useful habit to prepare yourself to sleep is reading a printed book, which is much better than e-reading to induce sleepiness (9).
• Listen to music: People with insomnia may benefit from listening to music, especially a type of music that induces relaxation (10).
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
Do You Really Need Drugs to Sleep?
You have probably not tried all of the recommendations we have mentioned above. By implementing a bedtime ritual, a significant proportion of insomniac people have improved their sleep without any drugs. Moreover, there are additional recommendations ahead that you can try, and only use drugs as an emergency alternative when nothing else works.
Overuse of benzodiazepines to sleep is a significant health problem, with several cases of overdose death, and growing sleep alterations. Instead of solving the issue in the long run, these prescription drugs make it worse still, and it was the third most commonly misused drug in the United States (11).
One of the safest approaches to treating sleeping problems is melatonin supplements, which are available in many forms. But there’s not enough data to know exactly how this drug works and more investigation in humans is required to reduce the adverse effects (unintended sedation and daytime sleepiness) (12).
Is there another safe alternative we can try?
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
Natural treatments for sleep problems
The advantage of using natural aids for sleep problems is that we will avoid the potential side effects of benzodiazepines and other drugs to treat insomnia. The majority are medicinal plants with sedative properties that you can drink at night in infusions and sleep teas. Some of them chamomile, peppermint leaves, lavender, and many others:
• Leaves of Melissa: It is also known as lemon balm, and it is useful to treat anxiety disorders that do not allow you to get asleep. It reduces symptoms such as palpitations and agitation, and both the taste and smell of this herb are found to be beneficial to calm down and find your inner peace (13, 14).
• Peppermint leaves: Aromatherapy with peppermint improves stress symptoms. Additionally, it is useful to calm down your gastrointestinal system and reduce abdominal discomfort, which sometimes impairs sleep (15, 16).
• Rose hips: An anti-inflammatory that relieves pain symptoms and allows you to relax for a good night’s sleep (17).
• Chamomile: One of the most powerful remedies against anxiety, chamomile is used to control the symptoms of major anxiety disorders and depression in adults (18).
• Fennel fruits: Along with chamomile and leaves of Melissa, fennel fruit extract is very useful in small children with infant colic. It reduces their symptoms in a very short period and allows them and their families to get back to sleep (19).
• Hibiscus petals: A herb with a significant stress-releaving potential, excellent for people who suffer from hypertension. It reduces the symptoms of agitation associated with high blood pressure (20).
• Lavender grass: Using lavender twice a day improves very severe anxiety problems, and reduces the recurrence of stressful thoughts that do not allow for quiet sleeping (21).
• Hawthorn flowers and fruits: A useful herb and fruit to improve mild to moderate anxiety syndromes. It is useful to calm down your body and mind before going to sleep (22).
• Lemongrass: It has an anxyolitic effect by activating neurons in the brain to release GABA, a type of inhibitory neurotransmitter that calms you down and promotes sleepiness (23).
• Cones of hops: An excellent aid against insomnia. People fall asleep faster by combining hops and other extracts. It helps insomnia and increases the quality of sleep (24).
• Flowers of linden: It has a strong anxiolytic and sedative effect, reducing stress and promoting sleep by triggering inhibitory activity in the central nervous system (25).
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
Lifestyle Changes & Recommendations
Besides having a fixed bedtime ritual and using herbal infusions, a series of easy lifestyle changes may also contribute to helping you achieve a restful night. The most significant changes you can implement are as follows (26):
• Use your bedroom appropriately: We should use the bed for two main activities: sleeping and having sex. Other than that, there’s no reason to watch television, work, and eat in your bed. If you use your bed to sleep, your mind will associate the comfort and special feel of your mattress with drowsiness, and you will not struggle so much to get asleep.
• Don’t force yourself to sleep: A typical question is what to do if you try everything and just can’t get to sleep. It is not healthy to feel growing anxiety to get asleep. If you do, sit up or go elsewhere, read a book, or choose a soothing activity to enjoy for a while. Then, get back to your bed and try to relax once again.
• Have a light dinner: Instead of a heavy dinner, reduce your intake a bit, and use dairy products, turkey, or cheese and crackers. They have tryptophan, an amino acid that your body transforms into sleep-inducing substances such as serotonin and melatonin.
• Reduce caffeine intake: Remember that caffeine is a stimulant of the central nervous system. So, cutting your caffeine intake is a wise step a few hours before going to sleep.
• Exercise often and at the right time: Exercising throughout the day is associated with better sleep patterns at night. If you go out and exercise in the early morning, you will also get direct sunlight and help your body regulate its internal clock. In time, you will feel your sleeping patterns slowly get back to normal.
Using all of the recommendations in this short guide will definitely achieve a gradual change. If they don’t have an immediate effect, it may take a while, and it depends on you to keep trying. The recommendations are the same, and there’s a lot to do before recurring to synthetic drugs with multiple side effects.
A Practical & Concise Guide on How to Recover Your Sleep & Beat Insomnia
Highlights
• Sleep is fundamental in humans and the majority of living beings because it clears the brain from metabolic debris and promotes better brain connections.
• Using a sleeping ritual is very useful for getting better sleep. It usually starts one hour before bedtime and may include meditation, massages, dimming the lights, getting a hot bath, or reading a printed book.
• Instead of using synthetic drugs to sleep, we can opt for natural treatments that do not cause addiction, such as Valerian, St. John’s Wort, Magnolia, Rosemary, Ginseng, and Green Tea.
• Other lifestyle recommendations we can follow to improve our sleep quality include not using the bedroom for activities other than sleep, exercise often, not forcing yourself to sleep when you feel anxiety, reduce our caffeine intake and have a light dinner closely before sleeping.
Sources:
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Brussels / 1 & 2 February 2020
schedule
IoT with CircuitPython
Look mam, no development environment.
Introduction to CircuitPython and how to make basic IoT without a development environment.
A brief history of CircuitPython CircuitPython vs MicroPython
Hello World demo: 1. Hello World in REPL 2. Hello World in a Python script 3. Blink (the electronic Hello World) 4. Cheerlights (the internet connectivity Hello World) 5. Hide and Seek (a BLE Hello World?)
Circuit Python supported hardware used for the IoT demo: * nRF52840 (Nordic Semiconductor) with build-in BLE * ATSAMD51 (Microchip) M4 with Airlift (ESP32 used as a Wifi Co-Processor)
Speakers
Photo of David Glaude David Glaude
Links
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Fitness Tip: How To Hydrate and Replace Electrolytes When Working Out
Image result for Fitness Tip: How To Hydrate and Replace Electrolytes When Working Out
Water is important to live. some days while not it may end in death - it's that necessary. thus considering an association strategy, particularly once figuring out within the heat is important to overall health. we tend to lose water through respiration, sweating also as urinary and fecal output. Exercise hurries up the speed of water loss creating an intense exercise, particularly within the heat, a clear stage of resulting in cramping, lightheadedness and warmth exhaustion or heat stroke if adequate fluid intake is not met. Correct fluid intake is a very important priority for exercisers and non-exercisers within the heat. Water makes up hr of our bodies. thus it's improbably necessary to for several completely different roles within the body.
The Role of association within the Body:
Water has several necessary jobs. From a solvent to a mineral supply, water plays a district in many alternative functions. Here square measure a number of water's necessary jobs:
- Water acts as a solvent or a liquid which will dissolve alternative solids, liquids, and gases. It will carry and transport this stuff in a very variety of the way. 2 of water's most vital roles square measure the actual fact that water transports nutrients to cells and carries waste product far from cells.
- within the presence of water, chemical reactions will proceed once they could be not possible otherwise. thanks to this, water acts as a catalyst to hurry up catalyst interactions with alternative chemicals.
- drain the cup as a result of water acts as a lubricant! meaning that water helps lubricate joints and acts as a cushion for the eyes and medulla spinalis.
- Body association and fluid exchange facilitate regulate temperature. do not be afraid to sweat! It helps to regulate your temperature. after we begin to sweat, we all know that temperature has accrued. As sweat stays on the skin, it begins to evaporate that lowers the temperature.
- Did you recognize that water contains minerals? drinkable is very important as a supply of metallic element and metallic element. once drinkable is processed, pollutants square measure removed and lime or sedimentary rock is employed to re-mineralize the water adding the metallic element and metallic element into the water. as a result of re-mineralization varies reckoning on the situation of the quarry, the mineral content also can vary.
Which Factors confirm what proportion of Water we tend to Need:
What factors have an effect on what proportion water would like? All of the subsequent facilitate confirm what proportion of water we tend to need to require it.
Climate - hotter climates might increase water wants by a further five hundred cubic centimeter (2 cups) of water per day.
Physical activity demands - a lot of or a lot of intense exercises would require a lot of water - reckoning on what proportion exercise is performed, water wants may double.
How much we've sweated - the number of sweating might increase water wants.
Body size - Larger individuals can probably need a lot of water and smaller individuals would require less.
Thirst - additionally associate degree indicator of after we want water. Contrary to in style believe that after we square measure thirsty we'd like water, thirst is not sometimes perceived till 1-2% of body weight is lost. At that time, exercise performance decreases and mental focus and clarity might drop off.
We know why water is very important however will we set about hydrating correctly?
We get water not solely through the beverages we tend to consume however additionally through a number of the food we tend to eat. Fruits and vegetables in their raw kind have the very best proportion of water. lyonnaise or "wet" carbohydrates like rice, lentils, and legumes have a good quantity of water wherever fats like kookie, seeds and oils square measure terribly low in water content.
Fluid wants By Bodyweight:
One of the best thanks for confirming what proportion of water you would like is by weight. this may be the fundamental quantity you would like daily while not exercise. *Yes, you'll have to search out a metric device like this one to try and do the maths.
Water Needs: thirty - forty cubic centimeter of water per one kilogram of bodyweight
Example: if you weigh fifty kilograms (110 lb), you'd want one.5 L - two L of water per day.
Hydration Indicators:
You should be drinkable systematically (not all at one time) throughout the day. The body will solely absorb an explicit quantity of water at a time. Any rabid drinking could lead to health problems.
Thirst - As declared on top of, if you are thirsty, you are already dehydrated.
Urine - the color of your excretory product is additionally associate degree indicator of your association level.
colorless to slightly yellow - hydrous
soft yellow - hydrous
pale gold - hydrous
gold, dark gold or brown - doable lightweight to moderate dehydration
brown - dehydrated
Hydration + solution Strategy:
These straightforward steps can assist you to hydrate daily and before and once workouts.
1. confirm what proportion of water you would like to drink on routine mistreatment the weight formula on top of.
2. Pre-hydration - Drinking concerning two cups of water BEFORE intense exercise ensures adequate association to begin.
3. throughout Exercise - one cup (8 ounces) of water mixed with electrolytes (about 3/4 water to 1/4 electrolyte) each quarter-hour or so.
4. once Exercise - Fluid intake is needed to help in recovery. ill with a combination of water, supermolecule and carbs could be a nice plan additionally to electrolytes if required. Formula: or so 15g of supermolecule, 30g of carbs, electrolytes, and water.
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WTF is wrong
I burned 4 games so far, and so far only 2 has worked. Whenever I do the swap trick for the other 2 it just freezes on the sega logo. The other games works fine and loads up great, but these 2 dont. I tried patching it already but still no luck, anyone can give some help?
Could be a few things wrong here.
1. You might simply be stuffing up the timing of the swap with these games.
2. If you are using the single swap method (ie original->copy), then the TOC on the original disc may differ from the TOC on the copy, causing the crash. Always use the double swap (copy->original->copy).
3. It also seems that some discs will not boot some games. I've never come up aginst this problem myself, but apparently it does exist. Try using a different original game to swap with.
Good luck
smile.gif
1. Im pretty sure Im getting it right cos my other 2 games boot
2. Yes I am using the double swap method, didnt even know the single one existed, also can the original be any game or do I have to have the original of the game Im am playing?
3. I tried 3 different games already, with the same results ???
What are the games you are having trouble with?
Apparently some games make extra security checks.
I can't remember any off the top of my head though. ???
Originally posted by Weapon@June 05 2002,22:49
1. Im pretty sure Im getting it right cos my other 2 games boot
2. Yes I am using the double swap method, didnt even know the single one existed, also can the original be any game or do I have to have the original of the game Im am playing?
3. I tried 3 different games already, with the same results ???
Ok then. With regards to 2, it doesn't matter. Because the TOC is read off the copied game it is correct for that game. Using the two swap method only the security ring is read from the original, and all security rings are supposed to be equal. If you haven't got it to boot with three different games then there must be something else wrong.
I suppose another possiblility is that your burns are bad. I suppose you could try booting them in one of the emulators to see if they get any further...
Also, when burning the games try to keep the burn speed down to 4x or lower. This can sometimes have a bearing, although it's been proven fairly conclusively that it is not an issue.
That's about all I can think of. With my own saturn, some games just refuse to run. Most notable is Andretti Racing. I have both a copy and the original, neither work (although not in the same way your games aren't working). It could be that the Saturn itself is damaged.
EDIT: Oh yeah, the games that require more than one swap with the original (ie check for the security ring more than once - Lemmings 3D and Alien Trilogy are examples of these) will just dump you back to the CD player screen if this is not done in time. No crashes.
the games I am having troubles with are virtua fighter remix and Dungeons and Dragons - Shadows Over Mystara. I dunno if its bad burns or what, wat is the url to the emu? and will the emu run all games?
if i'm not mistaken, those saturn emulators are currently running at a whopping 1fps
thus rendering any game you attempt to play with them other than turnbased stratagey games utterly unplayable
I had this problem with trying to boot newer third party games including 4mb RAM games. I used to use the swap trick with Daytona USA, it boted some games, but some wouldn't. I tried a few more including rips I did myself and they didn't work. I found using Xmen Vs Streetfighter can be used to do the swap trick on all backups including 4mb RAM Games even though it is an import. If you don't have the game, try a later Saturn release even if it's import.
Only you have the power to make dreams come true....
OR
You could try upgrading to the newest ASPI layer. By the way - what version of Windows are you using? XP has sucky CD support, especially for the Saturn emulators. If Force ASPI didn't work, I'd guess your CD-ROM doesn't work with the emus...yet.
yeah I got that **** ass XP OS
angry.gif
dammit, seems like it has alot of troubles. I tried ASPI 4.60 and force already, dunno wats left ???
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opencv进行图像分割
时间: 2023-11-07 20:52:48 浏览: 28
OpenCV提供了一些图像分割算法，包括基于阈值的分割、边缘检测、区域增长、分水岭算法等。 下面简单介绍一下基于阈值的分割： 1. 将图像转换为灰度图像。 2. 选择一个合适的阈值进行分割，可以使用全局阈值或自适应阈值。 3. 将图像分成两个部分，一部分是高于阈值的像素，另一部分是低于阈值的像素。 4. 对于高于阈值的像素，将其赋予一个值，对于低于阈值的像素，将其赋予一个不同的值。 下面是一个基于阈值的图像分割的示例代码： ``` python import cv2 # 读取图像 img = cv2.imread('image.jpg') # 将图像转换为灰度图像 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 应用全局阈值分割 ret, thresh = cv2.threshold(gray, 127, 255, cv2.THRESH_BINARY) # 显示结果 cv2.imshow('image', img) cv2.imshow('gray', gray) cv2.imshow('thresh', thresh) cv2.waitKey(0) cv2.destroyAllWindows() ``` 在这个示例中，我们首先读取了一张图像，并将其转换为灰度图像。然后，我们使用cv2.threshold()函数对灰度图像进行全局阈值分割。最后，我们使用cv2.imshow()函数显示原始图像、灰度图像和分割图像。
相关问题
opencv 文字图像分割
OpenCV文字图像分割是一种用于将文本区域从图像中分离出来的计算机视觉技术。这个过程涉及到将图像中的文本区域与背景区域进行分离，从而为文本检测、识别或分析等后续步骤提供更好的基础。 在实现文本图像分割时，可以通过以下步骤进行： 1. 图像预处理：首先对图像进行预处理，包括灰度化、二值化、去噪等操作。这些操作有助于提取出文字和背景的区别。 2. 文字区域提取：使用形态学操作、连通组件分析等方法，可以提取出图像中的文字区域。这些方法能够找到文字的边界和连通区域。 3. 分割与去除：通过分析提取到的文字区域，可以进行进一步的分割和去除杂质操作。例如，可以利用图像的连通性和形状特征，去除非文字的干扰。 4. 文字区域重建：从分割后的文字区域中，可以进行重建和连接操作，以提高文本的连续性。例如，可以通过基于几何形状和布局的方法，对分割后的文字区域进行重建和连接。 在实际应用中，可以根据具体的场景和需求选择不同的方法和技术。例如，可以使用基于阈值分割的方法、基于深度学习的方法等来实现文字图像分割。而OpenCV提供了丰富的函数库和工具，可以方便地进行图像处理和分析。 总之，OpenCV文字图像分割是通过将图像中的文字区域与背景区域进行分离，提取出文字的技术。通过预处理、区域提取、分割与去除、文字区域重建等步骤，可以实现对文字图像的分割和处理。
opencv 图像分割算法
OpenCV（Open Source Computer Vision Library）是一个开源的计算机视觉库，它提供了许多图像处理和计算机视觉算法。图像分割是计算机视觉中的一个重要任务，它可以将图像分成多个区域或对象。OpenCV提供了许多图像分割算法，包括阈值分割、区域生长、聚类、水平集方法等。 以下是几个常见的OpenCV图像分割算法的介绍： 1. 阈值分割（Thresholding）：阈值分割是一种简单的图像分割方法，它通过将图像中的像素值与一个阈值进行比较，将像素分为不同的类别。OpenCV提供了多种阈值分割算法，如全局阈值和自适应阈值等。 2. 区域生长（Region Growing）：区域生长是一种基于像素的图像分割方法，它通过将具有相似属性的像素组合成一个区域，并将其他像素标记为背景。OpenCV提供了区域生长算法的实现，可以根据不同的应用场景选择不同的生长算法。 3. 聚类（Clustering）：聚类是一种无监督的图像分割方法，它通过将相似的像素组合成群集，并将其他像素标记为背景。OpenCV提供了多种聚类算法，如K-means、DBSCAN等。 4. 水平集方法（Level Set Method）：水平集方法是近年来发展起来的一种先进的图像分割方法，它通过将图像中的边界或轮廓进行跟踪和演化，将图像分割成不同的区域。OpenCV提供了水平集方法的实现，可以根据不同的应用场景选择不同的水平集算法。 在使用OpenCV进行图像分割时，通常需要先对图像进行预处理，如滤波、去噪、缩放等，然后再选择合适的算法进行分割。OpenCV还提供了许多工具和函数，用于处理图像数据和执行各种计算机视觉任务。使用OpenCV进行图像分割可以大大提高效率和准确性，适用于各种计算机视觉应用场景。
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OpenCV中的图像分割算法是分水岭算法。该算法通过对图像进行预处理，使用cv2.watershed()函数实现分割。\[1\]在使用该函数之前，需要先对图像中的期望分割区域进行标注，将已确定的区域标注为正数，未确定的区域标注为0。分水岭算法将图像比喻为地形表面，通过标注的区域作为“种子”，实现图像分割。\[2\] 在OpenCV中，除了cv2.watershed()函数外，还可以借助形态学函数、距离变换函数cv2.distanceTransform()和cv2.connectedComponents()来完成图像分割的具体实现。\[3\]形态学函数用于对图像进行形态学操作，距离变换函数用于计算图像中每个像素点到最近边界的距离，而cv2.connectedComponents()函数用于将图像中的连通区域进行标记。 综上所述，OpenCV中的图像分割算法是分水岭算法，通过预处理和使用cv2.watershed()函数实现分割，同时还可以借助形态学函数、距离变换函数和cv2.connectedComponents()函数来完成图像分割的具体实现。 #### 引用[.reference_title] - *1* *2* *3* [OpenCV进行图像分割：分水岭算法（相关函数介绍以及项目实现）](https://blog.csdn.net/m0_62128864/article/details/124541624)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v91^control_2,239^v3^insert_chatgpt"}} ] [.reference_item] [ .reference_list ]
通过使用OpenCV库和Python编程语言，可以实现图像分割的任务。下面是一种基于K-means聚类算法的图像分割方法的示例代码： python import cv2 import numpy as np # 读取图像 img = cv2.imread("path_to_image.jpg") # 将图像转换为灰度图 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 使用K-means聚类算法进行图像分割 Z = gray.reshape((-1, 1)) Z = np.float32(Z) criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 10, 1.0) k = 2 # 聚类中心个数 ret, label, center = cv2.kmeans(Z, k, None, criteria, 10, cv2.KMEANS_RANDOM_CENTERS) center = np.uint8(center) res = center[label.flatten()] segmented_img = res.reshape((gray.shape)) # 显示分割结果 cv2.imshow("Segmented Image", segmented_img) cv2.waitKey(0) cv2.destroyAllWindows() 上述代码首先读取图像，并将其转换为灰度图像。然后使用K-means聚类算法对灰度图像进行分割，将像素值聚类为k个类别。最后，将分割结果可视化显示出来。 请注意，上述代码只是图像分割中的一种方法，其他图像分割方法也可以使用OpenCV中的不同函数来实现。具体选择哪种方法取决于实际需求和图像特征。123 #### 引用[.reference_title] - *1* *2* *3* [Python 计算机视觉（十二）—— OpenCV 进行图像分割](https://blog.csdn.net/qq_52309640/article/details/120941157)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 100%"] [ .reference_list ]
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Global opportunities and challenges on net-zero CO2 emissions towards a sustainable future
A. Joseph Nathanael, Kumaran Kannaiyan*, Aruna K. Kunhiraman, Seeram Ramakrishna, Vignesh Kumaravel
*Corresponding author for this work
Research output: Contribution to journalArticlepeer-review
Abstract
In recent years, global warming has been showing its deadliest impact on civilization through natural calamities. Given this situation, sustainable and economically viable CO2 capture, utilization, and storage (CCUS) techniques are the need of the hour more than ever before. Herein, cutting-edge technologies and materials for CO2 capture, conversion, and utilization are briefly discussed. The advances of various carbon capture technologies such as absorption, adsorption, membrane, and biochemical are investigated. Furthermore, the conversion of CO2 into value-added products with the help of single-atom catalysts, plasma technology, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs) is discussed in detail. MOFs and COFs have been receiving a great deal of attention as they offer material design flexibility to enhance the CO2 conversion efficiency. Among the existing methods, plasma technology has received the least attention; however, it has the potential to enhance the conversion rate, as demonstrated. On CO2 utilization, two significant energy-intensive technologies, refrigeration and air-conditioning and the organic Rankine cycle, that have the potential to utilize either pure or blended CO2 as their working fluid, are discussed. Specifically, the blending of CO2 with hydrocarbons has grabbed attention as a potential alternative natural working fluid with minimal environmental impact. The utilization of CO2 in commercial technologies primarily relies on the balance between performance enhancement and environmental benefits. Pilot-scale research projects and opportunities on CCUS technologies have also been discussed. This journal is
Original languageEnglish
Pages (from-to)2226-2247
Number of pages22
JournalReaction Chemistry & Engineering
Volume6
Issue number12
DOIs
StatePublished - Dec 2021
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\documentclass[a4paper, finnish, 12pt]{article} \usepackage[paperwidth=210mm, paperheight=297mm, top=20mm, bottom=25mm, left=30mm, right=30mm]{geometry} \usepackage{amsmath, amsfonts, amssymb, amsthm, marvosym} % matikkakomentoja \usepackage[dvips]{graphicx} \usepackage{psfrag, pstricks} \usepackage{pgfplots} \pgfplotsset{} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage[finnish]{babel} \usepackage{tikz} % mahdollistaa kuvien piirtämisen latexilla tikz-ympäristössä \usepackage{tkz-euclide} \usepackage{graphicx} % mahdollistaa kuvatiedostojen lisäämisen \usepackage{pdfpages} % mahdollistaa pdf-tiedostojen lisäämisen \usepackage{hyperref} % mahdollistaa linkkien lisäämisen \newcommand{\eqnum}[2][noname] {\begin{equation}\label{#1} \begin{split} #2 \end{split} \end{equation} } % numeroimaton yhtalo \newcommand{\eq}[2][noname] {\begin{equation*}\begin{split} #2 \end{split} \end{equation*} } \newcommand{\li}{\displaystyle \lim} \DeclareMathOperator{\dx}{d} % Derivaatan d \newcommand{\sij}[2]{\bigg/_{\mspace{-15mu}#1}^{\,#2}} % integraalin sijoitus -merkki %vector and matrix styles etc \newcommand{\vct}[1]{{\mathbf #1}} % vector symbol \newcommand{\mtx}[1]{{\mathrm #1}} % matrix symbol \newcommand{\real}{{\mathbb R}} % the set of real numbers \newcommand{\integ}{{\mathbb Z}} % the set of integers \newcommand{\luon}{{\mathbb N}} % the set of integers \newcommand{\rati}{{\mathbb Q}} % the set of integers \newcommand{\kom}{{\mathbb C}} % the set of integers \newcommand{\abs}[1]{\lvert {#1} \rvert} % absolute value \newcommand{\norm}[1]{\lVert {#1} \rVert} % vector norm \begin{document} \pagestyle{empty} \begin{flushright} \item[FYS-1080 2015-02 Teemu Salminen 256544] \end{flushright} \begin{description} \item[Tehtävä:] 1. Tyhjän hissin massa on $600kg$. Hissi on suunniteltu nousemaan $20.0m$ ajssa $16.0s$ ja sitä nostaa moottori, jonka maksimiteho on $40hp$. Mikä on suurin matkustajamäärä, jolla hissi toimii? (keskimäär. matkustaja $m=65.0kg$, $1hp=746W$). \item[Vastaus:] $P=40hp=40*746W=29840W$, $h=20.0m$, $\Delta t=16.0s$, $m=600kg+n65.0kg$.\\ $P=W/t=mgh/t=29840W\Rightarrow m=(29840W*t)/(gh)=(29840W*16.0s)/(9.81m/s^2*20.0m)=2433.435kg\Rightarrow m=2433kg=600kg+n65.0kg \Rightarrow n65.0kg=1833kg \Rightarrow n= 28.2 \Rightarrow 28$hlö. \item[Tehtävä:] 2. Lapsi työntää $m=10.0kg$:n kelkkaa x-akselin suuntaisella voimalla, joka on esitetty kuvassa. Laske voiman tekemä työ, kun kelkka liikkuu matkan (a) $x=0.0m..8.0m$ (b) $x=8.0m..12.0m$ (c) $x=0.0m..12.0m$. \begin{figure}[h] \begin{tikzpicture}[scale=0.4] \tkzInit[xmax=12,ymax=10,xmin=0,ymin=0] \tkzGrid \tkzAxeXY \draw[ thick,-] (0,0) -- (8,10) node[anchor=south west] {}; \draw[ thick,-] (8,10) -- (12,0) node[anchor=south west] {}; \end{tikzpicture} \end{figure} \item[Vastaus:] (a) Graafisella integroinnilla 43ruutua$=43Nm=43J$ (b) $20Nm=20J$ (c) $43J+20J=63J$ \item[Tehtävä:] 3. Vuoristoradan tyhjän vaunun paino on $m=120kg$. Pystysuorassa silmukassa, $r=12.0m$, pohjalla (a) vaunun nopeus on $25.0m/s$ ja silmukan huipulla (b) vaunun nopeus on $8.0m/s$. Mikä on kitkan tekemä vaunun noustessa väli $a-b$? \item[Vastaus:] $m=120kg$, $r=12.0m$, $v_1=25.0m/s$, $v_2=8.0m/s$. Valitaan silmukan pohja nollatasoksi. Tällöin huipulla $h=24.0m$.\\ $W_{\mu} = \Delta E = (E_{Ploppu}+E_{Kloppu})-(E_{Palku}+E_{Kalku})= (mgh_2 + 1/2mv_2^2)-(mgh_1 + 1/2mv_1^2)$ Sijoitetaan: \\ $W_{\mu} = 120kg*9.81m/s^2*24.0m + 1/2*120kg*(8.0m/s)^2 - 120kg*9.81m/s^2*0m - 1/2*120kg*(25.0m/s)^2=-5407.2N\approx -5400N$\\ Eli kitka vastustaa liikettä $5400N$ voimalla. \newpage \item[Tehtävä:] 4. Vuoristoradan vaunu ajaa kitkatta pystysuoran silmukan. Vaunu lasketaan liikkeelle korkeudelta $h$ ilman alkuvauhtia. (a) Mikä on minimikorkeus $h$ (suhteessa $r$), jolta vaunu kulkee silmukan? (b) Oletetaan, että $h=3.50R$ ja $r=20.0m$. Laske vaunun vauhti, säteittäinen kiihtyvyys ja tangentiaalinen kiihtyvyys silmukan loppuneljännespisteessä. Piirrä kiihtyvyyden komponentit. \item[Vastaus:] (a) Silmukan huipulla vaunuun vaikuttaa voimat $\bar{N}$ ja $\bar{G}$, molemmat alaspäin. Jotta vaunu pysyy raiteilla, tukivoiman $N$ täytyy olla vähintään 0. \\ Saadaan: $F_{tot}=N + mg = mv^2/r \rightarrow N=mv^2/r-mg \stackrel{N=0}{\rightarrow}v^2=gr \stackrel{*1/2m}{\rightarrow}1/2mgr=1/2mv^2$. Eli kineettisen energian huipulla täytyy olla vähintään $1/2mrg$. Valitaan potentiaalienergian nollatasoksi silmukan alapinta, jolloin $E_{Kloppu}+E_{Ploppu}=E_{Kalku}+E_{Palku}$ josta saadaan:\\ $1/2mgr+mgh_2 =1/2mv^2 + mgh_1 \stackrel{v=0, h_2=2r}{\rightarrow}mgh=1/2mgr+mg2r\rightarrow h=1/2r+2r=5/2r$. Eli lähtökorkeus $h$ täytyy olla vähintään $\frac{5}{2}r$.\\ (b) $r=20.0m$, $h=3.50r=70.0m$. \\Kohdassa A on $E_{KA} =1/2mv^2 = 0$ ja $E_{PA} = mgh=mg3.50r$.\\Kohdassa B on $E_{KB} = 1/2mgr$ ja $E_{PB} = mgh=mg2r$.\\Kohdassa C on $E_{KC}=1/2mv^2$ ja $E_{PC}=mgh=mgr$. \\ $1/2mv^2 + mg3.50r = 1/2mv^2 + mgr \rightarrow 1/2v^2 + g3.50r = 1/2v^2+gr \rightarrow g3.50r=1/2v^2+gr \rightarrow 1/2v^2 = g3.50r-gr \rightarrow v=\sqrt{2g3.5r-2gr}\Rightarrow v= \sqrt{2*9.81m/s^2*3.5*20.0m-2*9.81m/s^2*20.0m}=31.32m/s$\\ Vaunuun vaikuttaa vain putoamiskiihtyvyys $g=9.81m/s^2=a_t$.\\ $a_c=\frac{v^2}{r}=\frac{(31.32m/s)^2}{20.0m}=49.0499m/s\approx 49.0m/s$ \begin{figure}[h] \begin{tikzpicture}[scale=0.1] \tkzInit[xmax=0,ymax=0,xmin=0,ymin=0] \tkzGrid \draw[ thick,<-] (0,0) -- (49,0) node[anchor=south west] {$a_c$}; \draw[ thick,->] (0,0) -- (0,-9.8) node[anchor=south west] {$a_t$}; \end{tikzpicture} \end{figure} \item[Tehtävä:] 5. Kappale, $m=0.0400kg$ liikkuu $xy$-tasossa. Kappaleeseen kohdistuva nettovoima kuvataan potentiaalienergiana $U(x,y)= (5.80J/m^2)x^2+(3.60J/m^2)y^3$.\\ Mitkä ovat kappaleeseen kohdistuvan voiman ja kiihtyvyyden komponentit kohdassa $x=0.300m$, $y=0.600m$? \item[Vastaus:] x-suuntaiset: $F_x=-\partial U/\partial x \Rightarrow -2(5.80)x=-11.60x \Rightarrow F_x=-11.60*0.300m=-3.48N \Rightarrow F_x=ma_x \Rightarrow ma_x=-11.60x \Rightarrow 0.0400kg*a_x=-11.60*0.300m \Rightarrow a_x=-87m/s^2$ y-suuntaiset: $F_y=-\partial U/\partial y \Rightarrow -3(3.60)y^2 = -10.80y^2 \Rightarrow F_y=-10.80*(0.600m)^2 = -3.888N \Rightarrow ma_y=-10.80y^2 \Rightarrow 0.0400kg*a_y=-10.80(0.600m)^2 \Rightarrow 97.2m/s^2$\\ $a= \sqrt{a_x^2+a_y^2}=\sqrt{(-87)^2+(-97.2)^2} = 130.449m/s^2\approx 130.4m/s^2$\\ $tan(\theta)=a_y/a_x = 97.2/-87 \Rightarrow \theta=48.17^{\circ}$\\ V: $F_x=-3.48N$, $F_y=-3.89N$, $a=130.4m/s^2$, $\theta=48.17^{\circ}$. \newpage \item[Tehtävä:] 6. Pesäpalloon, $m=0.145kg$, isketään mailalla. Juuri ennen osumaa pallo etenee oikealle vauhdilla $50.0m/s$ ja se kimpoaa mailasta kulmaan $30^{\circ}$ vaakasuoraan nähden vauhdilla $65.0m/s$. Jos mailan ja pallon kontakti kestää $1.75ms$, mikä on keskimääräinen voima? \item[Vastaus:] $p=mv \Rightarrow p_1=mv_1=0.145kg*-50.0m/s=-7.25Ns$ Vain x-akselin suuntaista liikemäärää. $p_{2x} = mv_{2x} = 0.145kg*cos(30^{\circ})*65.0m/s=8.162Ns$ ja $p_{2y} = 0.145kg*sin(30^{\circ})*65.0m/s=4.713Ns$. Muutos x-suunnassa: $8.162Ns-(-7.25Ns)=15.412Ns$. Muutos y-suunnassa: $4.713Ns-0=4.713Ns$ Kokonaismuutos: $15.412Ns+4.713Ns=20.125Ns$. $J=F\Delta t \rightarrow F=J/\Delta t \Rightarrow F=20.125Ns/0.00175s=11500N$. \end{description} \end{document}
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pH Balance Friendly
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I like to think that the term pH balance is equivalent to gluten; it's often thrown around and talked about but no one knows what it actually is. If you're one of those people who doesn't know what gluten is, I can't help you - but if you're still not quite sure what pH balance is, then keep reading!
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What happens if the pH balance is off?
If the pH balance is off, the skin can have adverse reactions. See for yourself:
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2. When the pH balance is too acidic, one may experience inflammation and irritation. This effect is similar to what would happen if you put a harsh chemical peel on your skin; the skin becomes "burnt", sensitive, irritated and prone to break outs.
What is the ideal pH level?
The ideal pH level is on the acidic side; it falls between 4.5 and 5.5. An acidic pH kills bacteria and keeps the skin balanced, hydrated and rejuvenated. An acidic pH helps keep your skin balanced, hydrated, healthy, and radiant.
Does skin-type affect the pH level?
Yes, people with oily skin typically have a pH level that falls between 4 and 5.2. People with dry skin tend to have a pH above 5.5.
What factors affect the pH level?
Your pH level depends on a variety of factors such as: 1) diet; 2) sleep; 3) environment; and/or 4) skincare and cosmetic products.
How to restore balance in pH levels?
A balanced pH is maintained through healthy habits. Here is a list of some DOs and DONTs:
DO
1. Moisturize your skin - When the skin is dry it is prone to cracking. In other words, dry skin is vulnerable to wrinkles.
2. Use products that directly say they are pH balanced - Products that are pH balanced are very good for the skin. If your product doesn't mention it - it’s probably because it doesn’t include pH balancing properties and hence isn’t going to be good for your skin
3. Go NATURAL - Look for ingredients that are natural and won’t throw off your pH balance. Here are a couple examples of great ingredients to incorporate into your body care routine
• Aloe Vera Leaf Juice - nourishes and hydrates your skin.
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• Vitamin C
DONT
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| 0.989566 |
Open access peer-reviewed chapter
Deep Learning-Based Detection of Pipes in Industrial Environments
Written By
Edmundo Guerra, Jordi Palacin, Zhuping Wang and Antoni Grau
Submitted: 06 April 2020 Reviewed: 12 June 2020 Published: 14 July 2020
DOI: 10.5772/intechopen.93164
From the Edited Volume
Industrial Robotics
Edited by Antoni Grau and Zhuping Wang
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Abstract
Robust perception is generally produced through complex multimodal perception pipelines, but these kinds of methods are unsuitable for autonomous UAV deployment, given the restriction found on the platforms. This chapter describes developments and experimental results produced to develop new deep learning (DL) solutions for industrial perception problems. An earlier solution combining camera, LiDAR, GPS, and IMU sensors to produce high rate, accurate, robust detection, and positioning of pipes in industrial environments is to be replaced by a single camera computationally lightweight convolutional neural network (CNN) perception technique. In order to develop DL solutions, large image datasets with ground truth labels are required, so the previous multimodal technique is modified to be used to capture and label datasets. The labeling method developed automatically computes the labels when possible for the images captured with the UAV platform. To validate the automated dataset generator, a dataset is produced and used to train a lightweight AlexNet-based full convolutional network (FCN). To produce a comparison point, a weakened version of the multimodal approach—without using prior data—is evaluated with the same DL-based metrics.
Keywords
• deep learning
• autonomous robotics
• UAV
• multimodal perception
• computer vision
1. Introduction
Robotics, as a commercial technology, started to be widespread some decades ago, but instead of decreasing, it has been growing year by year with new contributions in all the related fields that it integrates. The introduction of new materials, sensors, actuators, software, communications and use scenarios converted Robotics in a pushing area that embraces our everyday life. New robotic morphologies are the most shocking aspect that society perceives (i.e., the first models of each type generally produce the largest impact), but the long-term success of robotics is found in its capability to automate productive processes. Manufacturers and developers know that the market is found not only in large-scale companies (car manufacturers and electronics mainly) but also in the SME that provides solutions to problems that are manually performed so far. Also, robotics has opened the doors to new applications that did not exist some years ago and are also attractive to investors. These facts, together with lower prices for equipment, better programming and communication tools, and new fast-growing user-friendly collaborative robotic frameworks, have pushed robotics technology at the edge in many areas.
It is clear that industrial robotics leads the market worldwide, but social/gaming uses of robots have increased sales. Nevertheless, the most promising scenario for the present time and short term is the use of robots in commercial applications out of the plant floor. Emergency systems, inspection, and maintenance of facilities of any kind, rescues, surveillance, agriculture, fishing, border patrolling, and many other applications (without military use) attract users/clients because their use increases the productivity of the different sectors, low prices and high profitability are the keys.
There exist many robot morphologies and types (surface, underwater, aerial, underground, legged, wheels, caterpillar, etc.) but authors want to draw attention in the unmanned aerial vehicles (UAVs), which have several properties that make them attractive for a set of application that cannot be done with any other type of robot. First, those autonomous robots can fly, and therefore, they can reach areas that humans or other robots cannot. They are light, easy to move from one area to another, and can be adapted to any area, terrain, soil, building, or facility. The drawback is the fragility in front of adverse meteorological events, and their autonomy is quite limited compared with unmanned surface vehicles (USVs).
UAVs have seen the birth of a new era of unthinkable cheap, easy applications up to now. The authors would like to focus its use in the maintenance and inspection of industrial facilities, but specifically in the inspection of pipes in big, complex factories (mainly gas and oil companies) where the manual inspection (and even location and mapping) of pipes becomes an impossible task. Manned helicopters (with thermal engines) cannot fly close to pipes or even among a bunch of pipes. Scaffolds cannot be put up in complex, unstable, and fragile pipes to manually inspect them. Therefore, a complex problem can be solved through the use of UAVs for inspecting pipes of different diameters, colors, textures, and conditions in hazardous factories. This problem is not new and some solutions have been brought to an incipient market. Works as those in [1, 2] propose the creation of a map of the pipe set navigating among it with odometry and inertial units [3]. Obstacle avoidance in a crowded 3D world of pipes becomes of great interest when planning a flight; in [4], some contributions are made in this direction although the accuracy of object is deficient to be a reliable technology. Work in [5] overcomes some of the latter problems with the use of a big range of sensors, cameras, laser, barometer, ultrasound, and a computationally inefficient software scheme made the UAV too heavy and unreliable due to the excessive sensor fusion approach.
Many of the technical developments that have helped robotics grow have had a wider impact, especially those related with increasing computational power and parallelization levels. Faster processors, with tens of cores and additional multiple threat capabilities, and modern GPUs (graphics processing unit) have led to the emergence of GPGPU (general-purpose computing on GPU). These type of computing techniques have led to huge advances in the artificial intelligence (AI) field, producing the emergence of the “deep learning” field. The deep learning (DL) field is focused in using artificial neural networks (ANNs) that present tens or hundreds of layers, exploiting the huge parallelization capabilities of modern GPU. This is used in exploiting computational cores (e.g., CUDA cores), which compared on a one-to-one basis with a processor core, they are less powerful and slower, but can be found in amounts of hundreds or thousands. This has allowed the transition from shallow ANN to the deeper architectures and innovations such as several types of convolutional layers. In this work, the authors present a novel approach to detect pipes in industrial environments based in fully convolutional networks (FCNs). These will be used to extract the apparent contour of the pipes, replacing most of the architecture developed in [6] and discussed in Section 2. To properly train these networks, a custom dataset relevant to the domain is required, so the authors captured a dataset and developed an automatic label generation procedure base in previous works. Two different state-of-the-art semantic segmentation approaches were trained and evaluated with the standard metrics to prove the validity of the whole approach. Thus, in the following section, some generalities about the pipe detection and positioning problem are discussed, and the authors’ previous work [6] on it, as it will be relevant later. The next section discusses the semantic segmentation problem as a way to extract the apparent contour, both surveying classical methods, considered for earlier works, and state of the art deep-learning-based methodologies. The fourth section describes how the automatic label generator using multimodal data was derived and some features to the process. The experimental section starts discussing the metrics employed to validate the results, the particularities of the domain dataset generated and describes how an AlexNet FCN architecture was trained through transfer learning and the results achieved. To conclude, some discussion on the quality of the results and possible enhancements is introduced, discussing which would be the best strategies to follow continuing this research.
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2. Related work
As it has been discussed, inspection and surveying are a frequent problem where UAV technologies are applied. The most common scenario found is that of a hard to reach infrastructure that is visually inspected through different sensors onboard a piloted UAV. Some projects have proposed the introduction of higher level perception and automation capacities, depending on the specific problem. In these cases, it is common to join state-of-the-art academic and industrial expertise to reach functional solutions.
In one of these projects, the specific challenge of accurately detecting and positioning a pipe in real time using only the hardware deployable in a small (per industry standards) UAV platform was considered (Figure 1), with several solutions studied and tested (including vision- and LIDAR-based techniques).
Figure 1.
One of the UAV used for the development of perception tasks in the AEROARMS project. Several sensors were deployed, processing them with a set of SBCs (single-board computers), including a Velodyne LiDAR, two different cameras, ultrasonic range-finder (height), and optical flow.
In the case of LIDAR-based detection, finding a pipe is generally treated as a segmentation problem in the sensor space (using R3 data collected as “point clouds”). There are many methods used for LIDAR detection, but the most successful are based on stochastic model fitting and registration, commonly in RANSAC (Random Sample Consensus [7]) or derived approaches [8, 9]. Three different data density levels were tested using the libraries available through ROS: using RANSAC over a map estimated by a SLAM technique, namely LOAM [10]; detecting the pipe in a small window of consecutive point clouds joined by an ICP-like approach [11]; and finally to simply work using the most recent point cloud. The first approach probed to be computationally unfeasible, no matter what optimization was tested, as even working with a single datum cloud point could be prohibitive if not done carefully. To enhance the performance, the single cloud point approach was optimized employing spatial and stochastic filtering to reduce the data magnitude, and a curvature filter allowed to reduce fake positives in degenerate configurations, producing robust results at between 1 and 4 Hz. To solve the same problem with visual sensors, a two-step strategy was used. In order to estimate the pose of the pipes to be found, they were assumed to be circular and regular enough to be modeled as a straight homogeneous circular cylinder. This allowed using a closed-form conic equation [12], which related the axis of the pipe (its position and orientation as denoted in Plücker coordinates) with the edges of its projection in the image space. While this solves the positioning problem, the detection probed to be a little more challenging: techniques based on edge detection, segmentation, or other classical computer vision methods used to work under controlled light but failed to perform acceptably in outdoor scenarios. This issue was solved by introducing human supervision, where an initial seed for the pipe in the image sensor space was provided (or validated) by a human and then tracked robustly through vision predicting it with the UAV odometry.
With these results, discussed in [6], it was apparent that a new solution was needed, as the LiDAR approaches were too slow and the vision-based techniques probed themselves unreliable. The final proposed solution was based on integrating data from the laser and the vision sensors: the RANSAC over LiDAR approach would detect robustly the pipe and provide an initial position, which would then be projected into the image space (accounting for displacements if odometry is available) and used as a seed for the vision-based pipeline described.
In that same work [6], a sensibility analysis studying the effects of the relative pose between the sensor and pipes is provided. Once the pipe is detected in the LiDAR’s space sensor, the cylinder model is projected into the R2 image space using a projection matrix derived from the calibrated camera model (assumed to be a thin lens pinhole model, per classic literature [13]). This provides a region or band of interest where to look for the edges of the pipe in the image and is useful to solve the degenerate conic equation up to scale (i.e., being a function of the radius). An updated architecture version of the process is depicted in Figure 2.
Figure 2.
The architecture of the multimodal perception pipeline combining LiDAR and camera vision. An updated version adds to previous works a validation step using odometric measurements.
The detailed architecture of the multimodal approach reveals how the LiDAR-based pipeline minimizes the data dimensionality by filtering non-curved surfaces (i.e., remove walls, floor, etc.) and also by removing entirely regions of the sensed space if priors or relevant data or the expected relative position of the pipe to the sensor is available. This was aimed at minimizing the size of the point cloud to be processed by the RANSAC step. To be able to project the detected pipe from the LiDAR sensor space into the camera image, some additional information was required: the rigid transformation between sensors (i.e., the calibration between LiDAR and camera) and an estimation of the odometry of the UAV. This is due because, even in the best assumption, with a performance slightly over 4 Hz, the delay between the captured point cloud and the produced estimation of the pipe would be over 200 ms. Therefore, the projection of the detected pipe to predict the area of interest to search the apparent contour has to consider the displacement during this period, not only the rigid LiDAR to camera transformation. This predicted region of interest is used in the vision process pipeline, with predictions of the appearance of the pipes into image space used to refine the contour search. This contour search relies on stacking a Hough transform to join line segment detector (LSD) detected segments (to overcome partial obstructions) on the relevant area and allows to choose the nearest correctly aligned lines. Notice that using a visual servoing library [14], an option to use data provided through human interaction was kept as available, though the integration of LiDAR detections as seeds into the visual pipeline made it unnecessary. To avoid degenerate or spurious solutions, a validation step (based on reprojection and “matching” of the Plückerian coordinates [15] for a tracked piped) was later introduced.
This architecture leads to a fast (limited by the performance of the vision-based part) and robust (based on the RANSAC resilience to spurious detections) pipe detector with great accuracy, which was deployed and test in a UAV. The main issue of the approach is the hardware requirements: access to odometry from the avionics systems, LiDAR, and camera sensors, and enough computing power to process them (beyond any other task required from the UAV). All this hardware is focused on solving what can be described as a semantic segmentation problem. This is relevant given the enormous changes produced in the last decade in the computer vision field, and how classic problems like semantic segmentation are currently solved.
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3. Semantic segmentation problem: classic approaches and deep learning (DL)
In the context of computer vision, the semantic segmentation problem is used to determine which regions of an image present an object of a given category, that is, a class or label is assigned to a given area (be it a pixel, window, or segmented region). The different granularity accepted is produced by how the technique and its solution evolved: for a long time, it was completely unfeasible to produce pixel-wise solutions, so images were split according to different procedures, which added a complexity layer to the problem.
Current off-the-shelf technologies have changed the paradigm, as GPUs present huge capabilities in terms of parallelization, while solid-state disks make fast reliable storage cheap. These technical advancements have increased dramatically the performance, complexity, and memory available for data representation, especially for techniques inherently strong in highly parallelized environments. One of the fields where the impact has been more noticeable has been the artificial intelligence community, where the artificial neural network (ANN) has seen a resurgence thanks to the support this kind of hardware provides to otherwise computationally unfeasible techniques. The most impactful development in recent years has been the convolutional neural networks (CNNs), which have become the most popular computer vision approach for several of the classic problem and the default solution for semantic segmentation.
To understand the impact of deep learning into our proposed solution, we will discuss briefly how the classical segmentation pipeline worked and how the modern CNN-based classifier became the modern semantic segmentation techniques.
3.1 Classic semantic segmentation pipeline
The classic semantic segmentation pipeline can be split into two generic blocks, namely image processing for feature extraction and feature level classification. The first block generally includes any image preprocessing done and resizing/resampling, splitting the image into the regions/windows, defining the granularity level of the classification, and finally, extracting the features itself. The features can be of any type and frequently the ones feed to the classification modules will be a composition of several individual features from different detectors. The use of different window/region-based approaches helps build up higher level features, and the classification can be refined at later stages with data from adjacent regions.
Notice that this kind of architecture generally relies on classifiers which required very accurate knowledge or a dataset with the classes to learn specified for each input so it can be trained. Figure 3 shows the detection of pipelines in classic semantic segmentation. Notice that to train the classifier, the image mask or classification result becomes also an input for the training process.
Figure 3.
Block diagram of a classical architecture approach for semantic segmentation using computer vision.
So, it can be seen that solving the semantic segmentation problem though classic pattern recognition methods requires acute insight into the specifics of the problem domain, as the features to be detected and extracted are built/designed specifically. This implies (as mentioned earlier) working from low-level features and explicitly deriving the higher level features from them is a very complex problem itself, as they are affected by the input characteristics, what is to be found/discriminated, and which techniques will be used in the classification part of the pipeline.
3.2 The segmentation problem with deep learning
Modern semantic segmentation techniques have organically evolved with the rise of the deep learning field to its current prominence. This evolution can be seen as a refinement in the scale of the inference produced from very coarse (image level probabilistic detection) to very fine (pixel level classification). The earliest ANN examples made probabilistic predictions about the presence of an object of a given class, that is, detection of objects with a probability assigned. The next step, achieved thanks to increased parallelization and network depth, was starting to tackle the localization problem, providing centroids and/or boxes for the detected classes (the use of classes instead of objects here is deliberate, as the instance segmentation problem, separating adjacent objects of the same class, would be dealt with much later).
The first big break into the classification problem was done by AlexNet [13] in 2012, when it won the ILSVRC challenge, with a score of 84.6% in the top-5 accuracy test, while the next best score was only 73.8% (based on classic techniques). AlexNet has since then become a known standard and a default network architecture to test problems, as it is actually not very deep or complex (see Figure 4). It presents five convolutional layers, with max-pooling after the first two, three fully connected layers, and a ReLU to deal with non-linearities. This clear victory of the CNN-based approaches was validated next year by Oxford’s VGG16 [16], one of the several architectures presented, winning the ILSVRC challenge with a 92.7% score.
Figure 4.
Diagram of the AlexNet architecture, showcasing its pioneering use of convolutional layers.
While several other networks have been presented with deeper architecture, relevant development focused on introducing new types of structures into the networks. GoogLeNet [17], the 2014 ILSVRC winner, achieved victory thanks to the novel contribution of the inception module, which validated the concept that the CNN layers of a network could operate in other orders different from the classic sequential approach. Another relevant contribution produced by technology giants was ResNet [18], which scored a win for Microsoft in 2016. The introduction of residual blocks allowed them to increase the depth to 152 layers while keeping initial data meaningful for training the deeper layers. These residual blocks architecture essentially forwards a copy of the received inputs of a layer; thus, later layers received the results and same inputs of prior layers and can learn from the residuals.
More recently, ReNet [19] architecture was used to extend recurrent neural networks (RNNs) to multidimensional inputs.
The jump from the classification problem with some spatial data to pixel level labeling (refining inference from image/region to pixel level) was presented by Long [20], with the fully convolutional network (FCN). The method they proposed was based on using the full classifier (like the ones just discussed) as layers in a convolutional network architecture. FCN architecture, and its derivatives like U-Net [21] are the best solutions to semantic segmentation for most domains. These derivatives may include classic methods, such as DeepLab’s [22] conditional random fields [23], which reinforces the inference from spatially distant dependencies, usually lost due to CNN spatial invariance. The latest promising contributions to the semantic segmentation problem are based on the encoder-decoder architecture, known as autoenconders, like for example SegNet [24].
For the works discussed in this chapter, a FCN16 model with AlexNet as a semantic segmentation model was used. The main innovation introduced by the general FCN was exploiting the classification power via convolution of the common semantic segmentation DL network, but at the same time, reversing the downsampling effect of the convolution operation itself. Taking AlexNet as an example, as seen in Figure 4, convolutional layers apply a filter like operation while reducing the size of the data forwarded to the next layer. This process allows producing more accurate “deep features” but at the same time also removes high-level information describing the spatial relation between the features found. Thus, in order to exploit the features from the deep layers while the keeping information from spatial relation, data from multiple layers has to be fused (with element-wise summation). In order to be able to produce this fusion, data from the deeper layers are upsampled using deconvolution. Notice that data from shallow layers will be coarser but contain more spatial information. Thus, up to three different levels can be processed through FCN, depending on the quantity of layers deconvoluted and fused, as seen in Figure 5.
Figure 5.
Detail of the skip architectures (FCN32, FCN16, and FCN8) used to produce results with data from several layers to recover both deep features and spatial information from shallow layers (courtesy of [25]).
More information on the detailed working of the different FCN models can be found in [25]. It is still worth noting that the more shallow layers are fused, the more accurate the model becomes, but according to the literature, the gain from FCN16 to FCN8 is minimal (below 2%).
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4. Automated ground truth labeling for multimodal UAV perception dataset
Classic methods using trained classifiers would pick designed features (based on several metrics and detectors, as discussed earlier) to parametrize a given sample and assign a label. This would allow creating small specific datasets, which could be used to infer the knowledge to create bigger datasets in a posterior step. The high specificity of the features chosen (generally with expert domain knowledge applied implicitly) with respect to the task generally made them unsuitable to export learning to other domains.
By contrast, deep learning offers several transfer learning options. That is, as it was proven by Yosinski [26], trained with a distant domain dataset are generally useful for different domains and usually better than training from an initial random state. Notice that the transferability of features decreases with the difference between the previously trained task and the target one and implies that the network architecture is the same up to the transferred layers at least.
With this concept in mind, we decided to build a dataset to train an outdoor industrial pipe detector with pixel level annotation to be able to determine the position of the pipe. While the ability of transfer learning allows us to skip building a dataset with several tens of thousands of images, and therefore, the authors will work with a few thousand, which were used to fine-tune the network. These orders of magnitude are required as a “shallow” deep network. For instance, the AlexNet already presents 60 million parameters.
Capturing and labeling a dataset is a cumbersome task, so we also set to automatize this task with minimal human supervision/interaction, exploiting the capabilities of the sensing architecture proposed in earlier works described in Section 2.
This framework, see Figure 6, uses the images captured by the UAV camera sensor, the data processed by the localization approach chosen (see Section 2) to obtain the UAV odometry, and pipe detection seeds from the RANSAC technique treating the LiDAR point cloud data. When a pipe (or generally a cylinder) is detected and segmented in the data sensor provided by the LiDAR, this is used to produce a label for the temporally near images, to identify the region of the image (the set of pixels) containing the pipe or cylinder detected and its pose w.r.t. the camera. Notice that even running the perception part, the camera works at a higher rate than the LiDAR, so the full odometric estimation is used to interpolate between pipe detections, to estimate where the label should be projected into the in-between images (just as it was described for the pipe prediction in Section 2).
Figure 6.
The framework proposed to automatically produce labeled datasets with the multimodal perception UAV.
This methodology was used to create an initial labeled dataset with actual data captured in real industrial scenarios during test and development flights, as it will be discussed in the next section.
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5. Experimental evaluation
To evaluate the viability of the proposed automated dataset generation methodology, we apply it to capture a dataset and train several semantic segmentation networks with it. To provide some quantitative quality measurement for the solutions produced, we use modified standard metrics for state-of-the-art deep learning, accounting that in our problem we are dealing with only one semantic class:
• PA (pixel accuracy): base metric, defined by the ratio between properly classified pixels TP and the total number of pixels in an image, pixtotal:
PA=TPpixtotalE1
Notice that usually, besides the PA the mean pixel accuracy (MPA) is provided, but in our case, it reduces to the same value of PA, thus it will not be provided.
• IoU (intersection over union): standard metric in segmentation. The ration is computed between the intersection and union of two sets, namely the found segmentation and the labeled ground truth. Conceptually, it equals to the ratio between the number of correct positives (i.e., the intersection of the sets) TP, over all the correct positives, spurious positives FP and false negatives FN (i.e., the union of both the ground truth and segmentation provided). Usually, it is used as mean IoU (MIU), averaging the same ratio for all classes.
IoU=TPTP+FP+FNE2
An additional metric usually computed along with the MIU is the frequency weighted MIU, which just weighs the average IoU computed at MIU according to the relative frequency of each class. The MIU, in our case, IoU is the most relevant metric and the most widely used when reporting segmentation results (semantic or otherwise).
5.1 Dataset generation results
The system proposed was implemented over the ROS meta-operating system, just as in previous works [6], where the UAV system used to capture the data is described. A set of real flights in simulated industry environments was performed, where flights around a pipe were done. During these flights, averaging ~240 s, an OTS USB camera was used to capture images (at 640 × 480 resolution), achieving an average frame rate of around 17 fps. This translated in around 20,000 raw images captured, including the parts of flight where no industry-like elements are present, thus of limited use.
Notice that as per the method described, the pipe to be found can be only labeled automatically when the LiDAR sensor can detect it; thus, the number of images was further reduced due to the range limitations of the LiDAR scanner. Other factors, such as vibrations and disruptions in the input or results of required perceptual data, further reduced the number of images with accurate labels.
Around ~2100 images were automatically labeled with a mask assigning a ground truth for the pipe in the image. After an initial human inspection of the assigned label, a further ~320 were rejected, obtaining a final set of 1750. The image rejected produced spurious ground truths/masks. Some of them had inconsistent data and the reprojection of the cylinder detected in through RANSAC in LiDAR scans was not properly aligned (error could be produced by spurious interpolation of poses, faulty synchronization data from the sensors, or due to deformation of the UAV frame, as it is impossible for it to be perfectly rigid). Another group presented partial detections (only one of the edges of the pipe is visible in the image), thus making it useless for the apparent contour optimization. A third type of error found was produced by the vision-based pipeline, where a spurious mask was generated, commonly some shadows/textures displace/retort the edge, or areas not pertaining to the pipe are assigned due similarity of the texture and complexity of delimiting the areas.
A sample of the labeling process can be seen in Figure 7, with the original image, the segmented pipe image, and approximations to centroid and bounding bow.
Figure 7.
Left: dataset image. Middle: bounding box and centroid of the region detected. Right: segmentation mask image.
Out of the several options available to test the validity of the dataset produced, the shallow architecture AlexNet was selected, as it could be easily trained and it would provide some insight in the performance that could be realistically expected from a CNN-based approach deployed in the limited hardware of a UAV.
According to previous literature, the dataset was divided into training, validation, and test at the standard ratio of 70, 15, and 15% respectively.
To match the input of AlexNet the images were resized to 256 × 256 resolution. This was mainly done to reduce the computational load, as the input size could be easily fit adjusting some parameters, like the stride. To train and test the network, the Pytorch library was used, which provides full support for its own implementation of AlexNet.
To produce some metrics relevant to the network architecture just trained, a modified version of the technique used to label the dataset was used. Note that this approach, as described in previous sections, uses LiDAR, cameras, and odometry to: acquire an initial robust detection (from LiDAR), track its projection and predict it in the camera image space (using odometric data), and finally determine its edges/contour in the image. The robustness of the LiDAR detection is mainly due to exploiting prior knowledge (in the form of the known radius of the pipe to detect) that cannot be introduced into the AlexNet architecture to produce a meaningful comparison. So, a modified method, referred to as NPMD (no-priors multimodal detector) was employed to estimate the accuracy of earlier work detector without priors. The main difference was modifying the LiDAR pipeline to be able to detect several pipes with different radius (as it should be considered unknown). This led to the appearance of false positives and spurious measurements, which in turn weakened the results produced by the segmentation part of the visual pipeline.
Thus, FCN with AlexNet classification was trained using a pre-trained model for AlexNet, with the standard stochastic gradient descend (SGD) with a momentum of 0.9. A learning rate of 10−3 was used, according to known literature, with image batches of 20. The weight decay and bias learning rate were set to standard values of 5.10−4 and 2, respectively. Without any prior data, and no benefit to obtain by doing otherwise reported in any previous works, the classifier layer was set to 0, and the dropout layer in the AlexNet left unmodified. This trained model produced the results found in Table 1.
AlexNetFCNUPMD
PA73.456.7
IoU58.642.1
Table 1.
Experimental results obtained by AlexNet-based FCN.
It can be seen that eliminating the seed/prior data from the multimodal detector made it rather weak, with very low values for IoU, signaling the presence of spurious detections and probably fake positives. The FCN-based solution was around 1.5 times better segmenting the pipe, being a clear winner. This was to be expected as we deliberately removed one of the key factors contributing to the LiDAR-based RANSAC detection robustness, the radius priors, leading to the appearance of spurious detections.
It is worth noting that although the results are not that strong in terms of metrics achieved for a single-class case, there are no other vision-only pipe detectors with better results in the literature, neither other approaches actually tested in real UAV’s platforms, like authors’ previous works [6].
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6. Conclusions
The field of computer vision has been greatly impacted by the advances in deep learning that have emerged in the last decade. This has allowed solving, with purely vision-based approaches, some problems that were considered unsolvable under this restriction. In the case presented, a detection and positioning problem, solved with limited hardware resources (onboard a UAV) in an industry-like uncontrolled scenario through a multimodal approach, has been solved with a vision-only approach. The previous multimodal approach relied in LiDAR, cameras, and odometric measurements (mainly from GPS and IMU) to extract data with complex algorithms like RANSAC and combine them to predict the position of a pipe and produce a measurement. This system was notable thanks to its robustness and performance but presented the huge requirements detailed in [6]. In order to solve the problem in a simpler and more affordable manner, a pure visual solution was chosen as the way to go, exploring the deep learning opportunities.
Although the switch to a pure visual solution meant that during its use, the procedure would only use the camera sensor, the multimodal approach was still used to capture data, and through a series of modifications, turn it into an automatic labeling tool. This allowed building a small but complete dataset with fully labeled images relevant to the problem that we were trying to solve. Finally, to test this dataset, we train a DL architecture able to solve the semantic segmentation problem. Thus, three different contributions have been discussed in this chapter: firstly, a dataset generator exploiting multimodal data captured by the perception system to be replaced has been designed and implemented; secondly, with this dataset generation tool, the data captured has been properly labeled so it can be used for DL applications; and finally, a sample lightweight network model for semantic segmentation, FCN with AlexNet classification, has been trained and evaluated to test the problem.
By the same reasons that there was no dataset available for our challenge and we had to capture and develop one dedicated to our domain, there were no related works to obtain metrics. In order to have some relevant metrics to compare the results of the developed approach, a modified version of [13] was produced and benchmarked without the use of prior knowledge. Under these assumptions, the new CNN-based method was able to clearly surpass the multimodal approach, though it still lacks robustness to be considered ready for industrial standards. Still, these initial tests have proven the viability of the built dataset generator and the utilization of CNN-based semantic segmentation to replace the multimodal approach.
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Acknowledgments
This research was funded by the Spanish Ministry of Economy, Industry and Competitiveness through Project 2016-78957-R.
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12. 12. Doignon C, de Mathelin M. A degenerate conic-based method for a direct fitting and 3-d pose of cylinders with a single perspective view. In: Proceedings 2007 IEEE International Conference on Robotics and Automation. Roma, Italy: IEEE; 10-14 July 2007. pp. 4220-4225
13. 13. Krizhevsky A, Sutskever I, Hinton GE. Imagenet classification with deep convolutional neural networks. In: Pereira F, Burges CJC, Bottou L, Weinberger KQ , editors. Advances in Neural Information Processing Systems 25. Curran Associates, Inc.; 2012. pp. 1097-1105
14. 14. Marchand E, Spindler F, Chaumette F. ViSP for visual servoing: A generic software platform with a wide class of robot control skills. IEEE Robotics and Automation Magazine. 2005;12(4):40-52
15. 15. Bartoli A, Sturm P. The 3D line motion matrix and alignment of line reconstructions. In: Proceedings of the 2001 IEEE Computer Society Conference on Computer Vision and Pattern Recognition, CVPR, Kauai, HI, USA. Vol. 1. 8-14 December 2001. pp. I-287-I-292
16. 16. Simonyan K, Zisserman A. Very Deep Convolutional Networks for Large-Scale Image Recognition. 2015. Available from: http://arxiv.org/abs/1409.1556
17. 17. Szegedy C, Liu W, Jia Y, Sermanet P, Reed S, Anguelov D, et al. Going deeper with convolutions. In: 2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). Boston, MA, USA; 7-12 June 2015. pp. 1-9
18. 18. He K, Zhang X, Ren S, Sun J. Deep residual learning for image recognition. In: 2016 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). Las Vegas, NV, USA; 27-30 June 2016. pp. 770-778
19. 19. Visin F, Kastner K, Cho K, Matteucci M, Courville A, Bengio Y. ReNet: A Recurrent Neural Network Based Alternative to Convolutional Networks. 2015. Available from: http://arxiv.org/abs/1505.00393
20. 20. Long J, Shelhamer E, Darrell T. Fully convolutional networks for semantic segmentation. In: 2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR). Boston, MA, USA; 7-12 June 2015. pp. 3431-3440
21. 21. Ronneberger O, Fischer P, Brox T. U-Net: Convolutional networks for biomedical image segmentation. In: Navab N, Hornegger J, Wells WM, Frangi AF, editors. Medical Image Computing and Computer-Assisted Intervention—MICCAI 2015. (Lecture Notes in Computer Science). Cham: Springer International Publishing; 2015. pp. 234-241
22. 22. Chen L-C, Papandreou G, Kokkinos I, Murphy K, Yuille AL. DeepLab: Semantic image segmentation with deep convolutional nets, Atrous convolution, and fully connected CRFs. IEEE Transactions on Pattern Analysis and Machine Intelligence. 2018;40(4):834-848
23. 23. Lafferty J, Mccallum A, Pereira F. Conditional random fields: Probabilistic models for segmenting and labeling sequence data. In: 2001 Conference on Machine Learning, ICML, Williamstown, MA, USA; 28 June-1 July 2001. pp. 282-289
24. 24. Badrinarayanan V, Kendall A, Cipolla R. SegNet: A deep convolutional encoder-decoder architecture for image segmentation. IEEE Transactions on Pattern Analysis and Machine Intelligence. 2017;39(12):2481-2495
25. 25. Shelhamer E, Long J, Darrell T. Fully convolutional networks for semantic segmentation. IEEE Transactions on Pattern Analysis and Machine Intelligence. 2017;39(4):640-651
26. 26. Yosinski J, Clune J, Bengio Y, Lipson H. How transferable are features in deep neural networks? In: Advances in Neural Information Processing Systems. Montrea (CANADA): Curran Associates, Inc.; 2014. pp. 3320-3328
Written By
Edmundo Guerra, Jordi Palacin, Zhuping Wang and Antoni Grau
Submitted: 06 April 2020 Reviewed: 12 June 2020 Published: 14 July 2020
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__label__pos
| 0.884787 |
Code Efficiency
Attention paid to making code efficient in speed and particularly in resource use is always worthwhile. This topic suggests some methods that should become familiar to Symbian developers for this platform.
Stack usage
Each thread in an application has a limited standard stack space of 8Kb, which should be carefully managed. Therefore:
• avoid copy-by-value, except for basic types
• create any large object or array on the heap rather than the stack
• minimise the lifetime of automatic variables by appropriately scoping them
The last point can be illustrated with the following example:
void ABadFunction()
{
TBigObject Object1;
TBigObject Object2;
TBigObject Object3;
GetTwoObjectValues(Object1,Object2);
Object3=SumObjects(Object1,Object2);
FunctionWithUnknownStackOverhead(Object3);
}
In the above code, Object1 and Object2 persist, using stack space, throughout the lifetime of the call to FunctionWithUnknownStackOverhead() , although they are not required by that time. They should be removed from the stack before the call is made. This can be achieved as follows:
void ABetterFunction()
{
TBigObject Object1;
GetTotalObjectValues(Object1);
FunctionWithUnknownStackOverhead(Object1);
}
void GetTotalObjectValues(TBigObject &aObject)
{
TBigObject Object1;
TBigObject Object2;
GetTwoObjectValues(Object1,Object2);
aObject=SumObjects(Object1,Object2);
}
By splitting the code into two functions, you ensure that the stack is used no more than required.
Function overloads
If a function definition has default arguments, and if that function often gets called with the caller assuming the default arguments, consider providing an overloaded function that doesn't have the additional arguments. This is because every time the compiler supplies a default parameter, it generates additional code where the function is called.
For example, if you have
void FunctionOne(TInt aInt=0);
which often gets called in code by the line
FunctionOne();
then consider supplying
void FunctionOne();
the contents of which might be:
void FunctionOne()
{
FunctionOne(0);
}
Pointers and references
Using a reference as a function argument may be more efficient than using a pointer. This is because the compiler has to preserve the value of the null pointer through all conversions.
Imagine a class CXxx which derives from a mixin class MYyy , as in
class CXxx : public CBase,public MYyy {...};
Then, to pass a pointer to a CXxx to a function taking a MYyy , the compiler has to add sizeof(CBase) to the pointer, except when that pointer is NULL . If cp is a CXxx* , and Func() a function taking an MYyy* , then what happens in a call like Func(cp) is something like this:
Func((MYyy* aM)(cp==NULL ? NULL : (TUint8*)cp+sizeof(CBase)));
Null references are not possible, so no test for NULL is necessary when they are used. On ARM, converting from CXxx* to MYyy* takes 8 instructions, whereas the CXxx& to MYyy& conversion takes only two.
Floating point maths
Floating point maths is sufficiently slow that it is worth looking to see if an alternative algorithm using only integer maths is available.
For example, given two TInts , aTop , and aBottom , instead of:
TReal a = (TReal)aTop;
TReal b = (TReal)aBottom;
TReal c = a/b+0.5;
TReal result;
Math::Round(result,c,0);
return (TInt)result;
you should use
return((2*aTop+aBottom)/(2*aBottom));
Inline functions
Inline functions are intended to speed up code by avoiding the expense of a function call, but retain its modularity by disguising operations as functions. Before using them, however, there are two issues that you should check:
• code compactness: limited memory resources may mean that the speed cost of a function call is preferable to large bodies of inline code
• binary compatibility: changing the implementation of an inline function can break binary compatibility. This is important if your code is going to be used by other Symbian developers.
The most common cases where inline functions are acceptable are:
• getter and setters for one- or two-machine word quantities: for example,
inline ConEnv() const { return iConEnv; };
• trivial constructors for T classes:
inline TPoint::TPoint(TInt aX, TInt aY) { iX=aX; iY=aY; };
• in the thin-template idiom: see Thin templates
• certain other operators and functions, possibly templated, whose definition, not subject to change, is to map one operation onto another, for example,
template <class T> inline T Min(T aLeft,T aRight)
{ return(aLeft<aRight ? aLeft : aRight); }
No test for NULL pointer when deleting object
C++ specifies that delete 0 does nothing, so that you need never write code such as
if (iX)
delete iX;
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__label__pos
| 0.966168 |
Glow Plug Warning Car Dashboard Light
Glow Plug Warning Car Dashboard Light
Glow Plug (Diesel): This light shows that the engine’s glow plugs are warming up and that the engine should not be started until this light goes out.
Diesel engines need preheating before starting, particularly when starting from cold, and the glow plug serves as a starting assistance. The Glow Plug Indicator will glow for a few seconds after the ignition switch is switched on, then turn off. The engine may be started after the indication has gone out. The duration of lighting varies based on the ambient temperature, the temperature of the water, and the state of the batteries. If the engine makes a false start, turn the ignition switch to the LOCK/OFF position for 10 seconds, then turn the ignition switch to the ON position for the preheating to occur again, and start the engine once the Glow Plug Indicator goes off. If the Glow Plug Indicator continues to illuminate after a few seconds or flashes on and off after the engine has warmed up, or comes on while driving, turn the ignition switch to the ON position.
What Exactly Are Glow Plugs?
A glow plug is a part of your car that aids in the starting of your diesel-powered engine. They’re especially important in colder climates, since cold weather may prohibit diesel engines from starting at all. To start correctly, diesel engines depend on the heat generated by compression in the chamber. When a diesel engine is without an external source of heat and is also exposed to very cold temperatures, the engine will not start. Diesel glow plugs are the answer to this problem!
It’s critical to understand not just how glow plugs operate and how to change them, but also how to keep your vehicle running in the winter. Because roadside breakdowns may be very hazardous, it’s critical to have the expertise required to resolve these problems no matter where you are.
Glow Plugs: How Do They Work?
In order to function, an engine needs not only air and fuel, but also an ignition point. Glow plugs work by heating the tiny coil of wire within the plug, also known as the element, with the help of a 1.5v battery located in the glow plug ignitor. In certain modern cars, this battery is occasionally seen installed on-board.
The kind of gasoline used in the vehicle, as well as the material of the element, will influence how hot it remains after the engine has started. The element, which is made up of many distinct metals alloyed together, will come into touch with methanol-containing fuel, and the interaction between the two will cause a catalytic reaction. The platinum is heated in this process, which also ignites the methanol.
Is the light on your Glow Plug Indicator flashing?
If your Glow Plug Indicator is flashing, it means that your vehicle’s ECU (engine management unit) has detected a fault that could be related to the glow plugs, the glow plug light, the glow plug control module, or even sensors that aren’t necessarily directly related to the glow plug igniter itself. When the ECU identifies a potential problem, it records diagnostic data that qualified mechanics using code readers may extract and analyze.
When the Glow Plug Indicator sign appears on your car, it is probable that your vehicle will enter “safe mode” to avoid engine damage. When your car is in safe mode, you will notice a significant decrease in performance. Depending on the severity of the problem, it may be safe to drive the car for very limited distances until you can fully diagnose and fix it.
Dealing with your glow plug indicator sign flickering may be very frustrating, as can dealing with your glow plug indicator not lighting up at all. Both are warning indications of a problem inside your car that may cause severe damage, therefore it is critical that you get the vehicle properly examined as soon as possible, avoid highway driving at all times, and never presume that the symbol is shown by mistake.
6 Symptoms of a Bad Glow Plug
bad glow plug
1 . Difficulty Starting the Vehicle
You can’t start a diesel engine with faulty glow plugs. A defective glow plug will not produce enough heat to preheat the cylinder and ignite the gasoline.
If it cannot generate heat quickly enough, it may take many tries to start the car. The car will not start at all if the glow plugs are almost dead and the ambient temperature is below freezing.
2.Poor engine power
after a difficult start, bad glow plugs will make it difficult for your car to run properly, due to improper combustion which reduces power and efficiency.
3. Slow Acceleration
While you can start a diesel engine with a faulty glow plug, the vehicle will not perform optimally. When you floor the accelerator without producing much speed, you will notice the first indication of decreased performance.
Poor acceleration may also be caused by other engine issues. However, if you observe any of these additional faulty glow plug symptoms in addition to poor acceleration, the cause is most likely one or more of your glow plugs.
4. Misfiring
Backfiring exhaust may create a slew of problems in your car. It happens when the gasoline fails to ignite properly inside the cylinder. Because the glow plug is so important in igniting fuel, you may presume that a misfire in a diesel engine is caused by your glow plugs.
5. Dark or White Exhaust Smoke
Several causes may contribute to dark gray or black exhaust smoke. If the issue is with the combustion process, you may have a problem with the glow plugs.
Dark smoke while accelerating is more frequent in diesel engines, but if this symptom happens with others on our list, a broken glow plug may be to blame.
6.Check Engine Light
Faulty glow plugs may cause the check engine light to illuminate, and when scanned with an OBD2 scanner, you will get a glow-plug-related error code such as P0380, which translates to “Glow Plug/Heater Circuit ‘A’ Malfunction.”
P0381, P0382, P0383, P0384, P0670, P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, P0679, P0680, P0681, P0682, P0683, and P0684 are additional glow plug-related diagnostic problem codes.
When should your glow plug control module be replaced?
Replacing your glow plugs or glow plug control module is a simple job that should be done every 60,000 miles (95,000 km). This will assist to guarantee that you don’t discover they’ve gone bad on a very chilly day.
HOW TO TEST THE GLOW PLUG?
READ HERE: https://www.yourmechanic.com/article/how-to-test-diesel-glow-plugs-by-ed-ruelas
Thank you -Erwin
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| 0.890273 |
Investigating the Diagnostic Stability of Schizophrenia vs Schizoaffective Disorder
Psychiatric TimesVol 40, Issue 4
What are the key diagnostic differences between schizophrenia and schizoaffective disorder?
schizophrenia
SewcreamStudio/AdobeStock
CASE VIGNETTE
“Mr Piety” is a 34-year-old white male with a history of chronic schizoaffective disorder, bipolar type. He was stable on a regimen of clozapine 125 mg twice daily and valproic acid 1500 mg at bedtime for more than a decade. He was noted to have morbid obesity, with a body mass index of 50 kg/m2. Mr Piety reported a history of 1 lifetime manic episode lasting less than 2 weeks in his late teens. Otherwise, he denied a history of manic symptoms. He also denied significant depressive symptoms. He did not feel that the valproic acid was particularly helpful.
Mr Piety’s psychiatrist changed his diagnosis from schizoaffective disorder to schizophrenia and tapered him off valproic acid over a period of 3 to 4 months. Mr Piety did not experience recurrence of any mood symptoms and there were no other changes to his psychotropic medication regimen. One year later, he had lost 26 lbs (8% of his baseline total body weight) and his BMI was 45.7. Less than 4 years later, he had lost 48 lbs (16% of his baseline total body weight) and his BMI was 42.
Schizoaffective disorder has been a controversial diagnosis since its inception, first appearing in DSM-III.1,2 In DSM-III-R, schizoaffective disorder required the presence of affective symptoms for a “substantial” period (the definition of “substantial” was not further specified) relative to the total duration of illness, with a period of at least 2 weeks characterized by psychotic symptoms in the absence of affective symptoms.2
The prevalence of DSM-IV schizoaffective disorder was nontrivial.3 However, the diagnostic reliability of schizoaffective disorder is low relative to other differential diagnoses, and overdiagnosis has been a concern.4
As a result, in DSM-5, more stringent criteria for the diagnosis were introduced, requiring the presence of affective symptoms for a majority of the course of illness (Table).5
Table. Selected Comparative DSM-5 Criteria for Schizophrenia and Schizoaffective Disorder
Table. Selected Comparative DSM-5 Criteria for Schizophrenia and Schizoaffective Disorder5
Many patients receive different diagnoses over time, including schizoaffective disorder, schizophrenia, and a mood disorder with psychotic features.4,6
The Current Study
Florentin and colleagues7 aimed to describe differences in demographic and hospitalization characteristics across different diagnostic groups, to compare the stability of the schizoaffective disorder diagnosis, and to assess changes in the incidence of schizoaffective disorder following changes to the diagnostic criteria in DSM-5.
The study authors extracted data from the national Psychiatric Case Registry from the Ministry of Health of Israel, which covers all psychiatric admissions and discharges in the country since 1950. They identified all psychiatric inpatients aged 18 to 65 years who had been hospitalized between 2010 and 2015 with a diagnosis of either schizophrenia or schizoaffective disorder on their last discharge. For each patient, all psychiatric diagnoses from hospitalizations between 1963 and 2017 were recorded. They included 16,341 patients with at least 2 hospitalizations during this period.
The authors trichotomized patients into diagnostic groups: (1) those who received a diagnosis only of schizophrenia, (2) those who received a diagnosis only of schizoaffective disorder, and (3) those with both diagnoses. These groups were compared based on age, sex, ethnicity, substance use disorder, total number of hospitalizations, and average length of stay.
Cohen’s κ coefficient was used to measure reliability between first vs last diagnosis and most frequent vs first and last diagnosis. They assessed “diagnostic constancy,” defined as the presence of the same diagnoses in more than 75% of hospitalizations. Logistic regression models were used to predict the stability between first and most frequent diagnosis.
In the study sample, 64.6% were schizophrenia only, 11.5% were schizoaffective only, and 23.9% had both diagnoses. Those with both diagnoses were older, had an earlier mean age at first hospitalization, had a higher prevalence of substance use disorder, and had a greater number of mean number of hospitalizations than those in the other 2 groups. The proportion of males was highest in the schizophrenia-only group.
Thirty-eight percent of patients with a first diagnosis of schizoaffective disorder subsequently received a diagnosis of schizophrenia, and 21% with a first diagnosis of schizophrenia subsequently received a diagnosis of schizoaffective disorder.
Overall, the κ (reliability) between the first and most frequent diagnosis was 0.71. With an increasing number of hospitalizations, the agreement between first and most frequent diagnosis decreased. There was little change in the proportion of patients who received a diagnosis of schizoaffective disorder at first hospitalization between the pre- and post-DSM-5 period (8.5% vs 10.7%).
Study Conclusions
The authors found that schizophrenia was 2.5 times more frequently diagnosed than schizoaffective disorder, which is similar to previous findings.3 The relative size of the schizoaffective-only group diminished with an increasing number of hospitalizations. Almost 40% of patients who first received a diagnosis of schizoaffective disorder subsequently received a diagnosis of schizophrenia.
Prospective diagnostic consistency was lower for schizoaffective disorder than for schizophrenia. The authors noted that the increased prevalence of substance use disorder comorbidity in the “both disorders” group may contribute to diagnostic instability. Finally, there was little chance in the incidence of schizoaffective disorder in the pre- vs post–DSM-5 period.
Study strengths included the large sample using a national case registry over a 50-year period and the unique approach to assessing diagnostic stability. The primary study limitation was the exclusion of patients with a last diagnosis of bipolar disorder. Other limitations included the retrospective design and the lack of availability of some clinical and prognostic factors.
The Bottom Line
The reliability of schizoaffective disorder is relatively low and its incidence has not decreased since the publication of DSM-5, despite stricter criteria.
Dr Miller is a professor in the Department of Psychiatry and Health Behavior at Augusta University in Augusta, Georgia. He is on the Editorial Board and serves as the schizophrenia section chief for Psychiatric Times®. The author reports that he receives research support from Augusta University, the National Institute of Mental Health, and the Stanley Medical Research Institute.
References
1. Maj M, Pirozzi R, Formicola AM, et al. Reliability and validity of the DSM-IV diagnostic category of schizoaffective disorder: preliminary dataJ Affect Disord. 2000;57(1-3):95-98.
2. Diagnostic and Statistical Manual of Mental Disorders: DSM-3. 3rd ed. American Psychiatric Association; 1980.
3. Perälä J, Suvisaari J, Saarni SI, et al. Lifetime prevalence of psychotic and bipolar I disorders in a general populationArch Gen Psychiatry. 2007;64(1):19-28.
4. Fusar-Poli P, Cappucciati M, Rutigliano G, et al. Diagnostic stability of ICD/DSM first episode psychosis diagnoses: meta-analysis. Schizophr Bull. 2016;42(6):1395-1406.
5. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 5th ed. American Psychiatric Association; 2013.
6. Bromet EJ, Kotov R, Fochtmann LJ, et al. Diagnostic shifts during the decade following first admission for psychosis. Am J Psychiatry. 2011;168(11):1186-1194.
7. Florentin S, Reuveni I, Rosca P, et al. Schizophrenia or schizoaffective disorder? A 50-year assessment of diagnostic stability based on a national case registrySchizophr Res. 2023;252:110-117.
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| 0.613553 |
001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.hbase.replication;
020
021import org.apache.yetus.audience.InterfaceAudience;
022import org.apache.hadoop.hbase.wal.WAL.Entry;
023
024/**
025 * Skips WAL edits for all System tables including META
026 */
[email protected]
028public class SystemTableWALEntryFilter implements WALEntryFilter {
029 @Override
030 public Entry filter(Entry entry) {
031 if (entry.getKey().getTableName().isSystemTable()) {
032 return null;
033 }
034 return entry;
035 }
036}
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__label__pos
| 0.613353 |
Learn More
CRISPR-Cas is a prokaryotic adaptive immune system that provides sequence-specific defense against foreign nucleic acids. Here we report the structure and function of the effector complex of the Type III-A CRISPR-Cas system of Thermus thermophilus: the Csm complex (TtCsm). TtCsm is composed of five different protein subunits (Csm1-Csm5) with an uneven(More)
The CRISPR-Cas system is a prokaryotic host defense system against genetic elements. The Type III-B CRISPR-Cas system of the bacterium Thermus thermophilus, the TtCmr complex, is composed of six different protein subunits (Cmr1-6) and one crRNA with a stoichiometry of Cmr112131445361:crRNA1. The TtCmr complex copurifies with crRNA species of 40 and 46 nt,(More)
IL-4 has been shown to be involved in the accumulation of leukocytes, especially eosinophils, at sites of inflammation by acting on vascular endothelial cells. To identify novel molecules involved in the IL-4-dependent eosinophil extravasation, cDNA prepared from HUVEC stimulated with IL-4 was subjected to differential display analysis, which revealed a(More)
The lipase gene from Pseudomonas aeruginosa was randomly mutated by error-prone PCR to obtain thermostable mutants, followed by screening for thermostable mutant lipases. Out of about 2,600 transformants, four thermostable clones were obtained. Their nucleotide sequences showed that they had two or three amino acid substitutions. Analysis of the thermal(More)
D-Alanine-D-alanine ligase (Ddl) is one of the key enzymes in peptidoglycan biosynthesis and is an important target for drug discovery. The enzyme catalyzes the condensation of two D-Ala molecules using ATP to produce D-Ala-D-Ala, which is the terminal peptide of a peptidoglycan monomer. The structures of five forms of the enzyme from Thermus thermophilus(More)
Adaptive immunity in bacteria involves RNA-guided surveillance complexes that use CRISPR (clustered regularly interspaced short palindromic repeats)-associated (Cas) proteins together with CRISPR RNAs (crRNAs) to target invasive nucleic acids for degradation. Whereas type I and type II CRISPR-Cas surveillance complexes target double-stranded DNA, type III(More)
Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is believed to be a potent mediator of peritoneal fluid accumulation and angiogenesis and of tumor growth in ascites tumor. Such roles, however, have not been generally established because of insufficient quantitative and systemic analyses. To address this, we examined(More)
Size exclusion chromatography of the cytosolic fraction of SecA-overproducing cells of Escherichia coli suggested that SecA, an essential component of the secretory machinery, exists as an oligomer. The subunit structure of SecA was then studied using a purified specimen. Estimation of the molecular mass by means of ultracentrifugation and chemical(More)
Interactions between SecA and cellular components involved in the translocation of secretory proteins across the cytoplasmic membrane of Escherichia coli were studied by examining changes in the sensitivity of SecA to staphylococcal protease V8. In the presence of ATP, the amino-terminal 95-kDa portion of the SecA molecule became highly resistant to V8(More)
Genome analyses have revealed that members of the Lrp/AsnC family of transcriptional regulators are widely distributed among prokaryotes, including both bacteria and archaea. These regulatory proteins are involved in cellular metabolism in both global and specific manners, depending on the availability of the exogenous amino acid effectors. Here we report(More)
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| 0.668571 |
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service * National Institutes of Health
Summary
Occasional over indulgent Alcohol users and those that consume alcohol above the recommended average daily consumption (1 drink per day for women and up to 2 drinks per day for men) run the risk of diminished nutrient digestion and nutrient utilization through a number of complex mechanisms. Additionally, alcohol affects blood glucose levels leading to depravation of brain energy and function. Certain nutritional supplements (mainly; Vitamins B- 12, 6,5,3,2, C, D, E, folate, calcium, iron) may affect these implications and reverse the negative effects. An individual should consult with their doctor before subscribing to any nutritional supplement regimen. Abstinence from alcohol is preferred.
Alcohol and Nutrition
Nutrition is a process that serves two purposes: to provide energy and to maintain body structure and function. Food supplies energy and provides the building blocks needed to replace worn or damaged cells and the nutritional components needed for body function. Alcohol users often eat poorly, limiting their supply of essential nutrients and affecting both energy supply and structure maintenance. Furthermore, alcohol interferes with the nutritional process by affecting digestion, storage, utilization, and excretion of nutrients (1).
Impairment of Nutrient Digestion and Utilization
Once ingested, food must be digested (broken down into small components) so it is available for energy and maintenance of body structure and function. Digestion begins in the mouth and continues in the stomach and intestines, with help from the pancreas. The nutrients from digested food are absorbed from the intestines into the blood and carried to the liver. The liver prepares nutrients either for immediate use or for storage and future use.
Alcohol inhibits the breakdown of nutrients into usable molecules by decreasing secretion of digestive enzymes from the pancreas (2). Alcohol impairs nutrient absorption by damaging the cells lining the stomach and intestines and disabling transport of some nutrients into the blood (3). In addition, nutritional deficiencies themselves may lead to further absorption problems. For example, folate deficiency alters the cells lining the small intestine, which in turn impairs absorption of water and nutrients including glucose, sodium, and additional folate (3).
Even if nutrients are digested and absorbed, alcohol can prevent them from being fully utilized by altering their transport, storage, and excretion (4). Decreased liver stores of vitamins such as vitamin A (5), and increased excretion of nutrients such as fat, indicate impaired utilization of nutrients by alcohol users (3).
Alcohol and Energy Supply
The three basic nutritional components found in food--carbohydrates, proteins, and fats--are used as energy after being converted to simpler products. Some alcohol users ingest as much as 50 percent of their total daily calories from alcohol, often neglecting important foods (3,6).
Even when food intake is adequate, alcohol can impair the mechanisms by which the body controls blood glucose levels, resulting in either increased or decreased blood glucose (glucose is the body's principal sugar) (7). In nondiabetic moderate alcohol users, increased blood sugar, or hyperglycemia--caused by impaired insulin secretion--is usually temporary and without consequence. Decreased blood sugar, or hypoglycemia, can cause serious injury even if this condition is short lived. Hypoglycemia can occur when a fasting or malnourished person consumes alcohol. When there is no food to supply energy, stored sugar is depleted, and the products of alcohol metabolism inhibit the formation of glucose from other compounds such as amino acids (7). As a result, alcohol causes the brain and other body tissue to be deprived of glucose needed for energy and function.
Although alcohol is an energy source, how the body processes and uses the energy from alcohol is more complex than can be explained by a simple calorie conversion value (8). For example, alcohol provides an average of 20 percent of the calories in the diet of the upper third of drinking Americans, and we might expect many drinkers who consume such amounts to be obese. Instead, national data indicate that, despite higher caloric intake, drinkers are no more obese than nondrinkers (9,10). Also, when alcohol is substituted for carbohydrates, calorie for calorie, subjects tend to lose weight, indicating that they derive less energy from alcohol than from food (summarized in 8).
The mechanisms accounting for the apparent inefficiency in converting alcohol to energy are complex. (11), but several mechanisms have been proposed. For example, over drinking triggers an inefficient system of alcohol metabolism, the microsomal ethanol-oxidizing system (MEOS) (1). Much of the energy from MEOS-driven alcohol metabolism is lost as heat rather than used to supply the body with energy.
Research indicates that the majority of sometimes over indulgent drinkers may have detectable nutritional deficiencies. Because some alcohol users tend to eat poorly--often eating less than the amounts of food necessary to provide sufficient carbohydrates, protein, fat, vitamins A and C, the B vitamins, and minerals such as calcium and iron (6,9,26)--a major concern is that alcohol's effects on the digestion of food and utilization of nutrients may shift a well-nourished person towards a malnourished person and in some cases (daily alcohol use) severe malnutrition.
Summary
Occasional over indulgent Alcohol users and those that consume alcohol above the recommended average daily consumption (1 drink per day for women and up to 2 drinks per day for men) run the risk of diminished nutrient digestion and nutrient utilization through a number of complex mechanisms. Additionally, alcohol affects blood glucose levels leading to depravation of brain energy and function. Certain nutritional supplements (mainly; Vitamins B- 12, 6,5,3,2, C, D, E, folate, calcium, iron) may affect these implications and reverse the negative effects. An individual should consult with their doctor before subscribing to any nutritional supplement regimen. Abstinence from alcohol is preferred.
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service * National Institutes of Health
REFERENCES AVAILABLE UPON REQUEST: REPRINTS AVAILABLE
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Quick Answer: What Is The Side Effects Of B12 Injections?
How long do B12 injection side effects last?
How long will the effects of a B12 shot last? The effects of our shots vary between individuals. Most people feel the effects for about one week.
Who should not take B12 injections?
B-12 deficiency risk factors
alcohol abuse. smoking. certain prescription medications, including antacids and some type 2 diabetes drugs. having an endocrine-related autoimmune disorder, such as diabetes or a thyroid disorder.
What does vitamin B12 injections do for you?
Vitamin B-12 is also added to some foods and is available as a dietary supplement. Vitamin B-12 injections are commonly prescribed to help prevent or treat pernicious anemia and B-12 deficiency.
How do you feel after B12 injections?
The injection is given into a muscle (known as an intramuscular injection). You may have some pain, swelling or itching where your injection was given. However this is usually mild and will wear off quite quickly.
How often should you get B12 injections?
Once your B12 levels stabilize, you only need to administer every three to four days for 2-3 weeks. To maintain appropriate levels, it is suggested you take one B12 injection monthly and frequently get blood tests to determine future treatment.
You might be interested: How Much B12 Is Safe To Take Daily?
What happens when your vitamin B12 is low?
Not having enough B12 can lead to anemia, which means your body does not have enough red blood cells to do the job. This can make you feel weak and tired. Vitamin B12 deficiency can cause damage to your nerves and can affect memory and thinking.
Does B12 injections cause weight gain?
Despite the numerous processes in which vitamin B12 is involved, there’s little evidence to suggest that it has any influence on weight gain or loss.
What medications should not be taken with B12?
Certain medications can decrease the absorption of vitamin B12, including: colchicine, metformin, extended-release potassium products, antibiotics (such as gentamicin, neomycin, tobramycin), anti-seizure medications (such as phenobarbital, phenytoin, primidone), medications to treat heartburn (such as H2 blockers
How long does B12 deficiency take to correct?
Recovery from vitamin B12 deficiency takes time and you may not experience any improvement during the first few months of treatment. Improvement may be gradual and may continue for up to six to 12 months.
Does B12 help with belly fat?
If you want to lose excess weight, vitamin B12 has been linked to weight loss and energy enhancing. Vitamin B12 plays a major role in the body’s essential functions, including DNA synthesis. Vitamin B12 also helps the body convert fats and proteins into energy.
What vitamins help lose belly fat?
1. B vitamins
• B-12 is essential for the metabolism of proteins and fats. It needs B-6 and folate to work correctly.
• B-6 also helps metabolize protein.
• Thiamine helps the body metabolize fat, protein, and carbohydrates.
You might be interested: Often asked: What Does B12 Do In Anemia?
When does B12 shot start working?
A response usually is seen within 48 to 72 hours, with brisk production of new red blood cells. Once B12 reserves reach normal levels, injections of vitamin B12 will be needed every one to three months to prevent symptoms from returning.
Do B12 injections help with fatigue?
The B vitamins, and particularly vitamin B12, play a vital role in how your body produces what it needs for energy. If you’re deficient in vitamin B12, an injection will definitely give your energy level a boost. In fact, one of the first signs of vitamin B12 deficiency is fatigue.
Where do you inject B12?
The thigh is the most common injection site for intramuscular self-injections, but one may also inject the vitamin B12 shot at the shoulder and the upper buttocks. Experienced doctors commonly give a B12 shot in the deltoid muscle, but this is more difficult to do if you are just learning.
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Intro to Redis With Spring Boot
DZone 's Guide to
Intro to Redis With Spring Boot
In this tutorial, get an introduction Spring Data Redis and learn one way of connecting it to a web application to perform CRUD operations.
· Database Zone ·
Free Resource
In this article, we will review the basics of how to use Redis with Spring Boot through the Spring Data Redis library.
We will build an application that demonstrates how to perform CRUD operations Redis through a web interface. The full source code for this project is available on GitHub.
What Is Redis?
Redis is an open-source, in-memory key-value data store, used as a database, cache, and message broker. In terms of implementation, Key-Value stores represent one of the largest and oldest members in the NoSQL space. Redis supports data structures such as strings, hashes, lists, sets, and sorted sets with range queries.
The Spring Data Redis framework makes it easy to write Spring applications that use the Redis Key-Value store by providing an abstraction to the data store.
Setting Up a Redis Server
The server is available for free here.
If you use a Mac, you can install it with homebrew:
brew install redis
Then start the server:
mikes-MacBook-Air:~ mike$ redis-server
10699:C 23 Nov 08:35:58.306 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
10699:C 23 Nov 08:35:58.307 # Redis version=4.0.2, bits=64, commit=00000000, modified=0, pid=10699, just started
10699:C 23 Nov 08:35:58.307 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
10699:M 23 Nov 08:35:58.309 * Increased maximum number of open files to 10032 (it was originally set to 256).
_._
_.-``__ ''-._
_.-`` `. `_. ''-._ Redis 4.0.2 (00000000/0) 64 bit
.-`` .-```. ```\/ _.,_ ''-._
( ' , .-` | `, ) Running in standalone mode
|`-._`-...-` __...-.``-._|'` _.-'| Port: 6379
| `-._ `._ / _.-' | PID: 10699
`-._ `-._ `-./ _.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' | http://redis.io
`-._ `-._`-.__.-'_.-' _.-'
|`-._`-._ `-.__.-' _.-'_.-'|
| `-._`-._ _.-'_.-' |
`-._ `-._`-.__.-'_.-' _.-'
`-._ `-.__.-' _.-'
`-._ _.-'
`-.__.-'
10699:M 23 Nov 08:35:58.312 # Server initialized
10699:M 23 Nov 08:35:58.312 * Ready to accept connections
Maven Dependencies
Let’s declare the necessary dependencies in our pom.xml for the example application we are building:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
Redis Configuration
We need to connect our application with the Redis server. To establish this connection, we are using Jedis, a Redis client implementation.
Config
Let’s start with the configuration bean definitions:
@Bean
JedisConnectionFactory jedisConnectionFactory() {
return new JedisConnectionFactory();
}
@Bean
public RedisTemplate<String, Object> redisTemplate() {
final RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
template.setConnectionFactory(jedisConnectionFactory());
template.setValueSerializer(new GenericToStringSerializer<Object>(Object.class));
return template;
}
The JedisConnectionFactory is made into a bean so that we can create a RedisTemplate to query data.
Message Publisher
Following the principles of SOLID, we create a MessagePublisher interface:
public interface MessagePublisher {
void publish(final String message);
}
We implement the MessagePublisher interface to use the high-level RedisTemplate to publish the message since the RedisTemplate allows arbitrary objects to be passed in as messages:
@Service
public class MessagePublisherImpl implements MessagePublisher {
@Autowired
private RedisTemplate<String, Object> redisTemplate;
@Autowired
private ChannelTopic topic;
public MessagePublisherImpl() {
}
public MessagePublisherImpl(final RedisTemplate<String, Object> redisTemplate, final ChannelTopic topic) {
this.redisTemplate = redisTemplate;
this.topic = topic;
}
public void publish(final String message) {
redisTemplate.convertAndSend(topic.getTopic(), message);
}
}
We also define this as a bean in RedisConfig:
@Bean
MessagePublisher redisPublisher() {
return new MessagePublisherImpl(redisTemplate(), topic());
}
Message Listener
In order to subscribe to messages, we need to implement the MessageListener interface: each time a new message arrives, a callback gets invoked and the user code executed through a method named onMessage. This interface gives access to the message, the channel it has been received through, and any pattern used by the subscription to match the channel.
Thus, we create a service class to implement MessageSubscriber:
@Service
public class MessageSubscriber implements MessageListener {
public static List<String> messageList = new ArrayList<String>();
public void onMessage(final Message message, final byte[] pattern) {
messageList.add(message.toString());
System.out.println("Message received: " + new String(message.getBody()));
}
}
We add a bean definition to RedisConfig:
@Bean
MessageListenerAdapter messageListener() {
return new MessageListenerAdapter(new MessageSubscriber());
}
RedisRepository
Now that we have configured the application to interact with the Redis server, we are going to prepare the application to take example data.
Model
For this example, we are defining a Movie model with two fields:
private String id;
private String name;
//standard getters and setters
Repository interface
Unlike other Spring Data projects, Spring Data Redis does offer any features to build on top of the other Spring Data interfaces. This is odd for us who have experience with the other Spring Data projects.
Often, there is no need to write an implementation of a repository interface with Spring Data projects. We simply just interact with the interface. Spring Data JPA provides numerous repository interfaces that can be extended to get features such as CRUD operations, derived queries, and paging.
So, unfortunately, we need to write our own interface and then define the methods:
public interface RedisRepository {
Map<Object, Object> findAllMovies();
void add(Movie movie);
void delete(String id);
Movie findMovie(String id);
}
Repository Implementation
Our implementation class uses the redisTemplate defined in our configuration class RedisConfig.
We use the HashOperations template that Spring Data Redis offers:
@Repository
public class RedisRepositoryImpl implements RedisRepository {
private static final String KEY = "Movie";
private RedisTemplate<String, Object> redisTemplate;
private HashOperations hashOperations;
@Autowired
public RedisRepositoryImpl(RedisTemplate<String, Object> redisTemplate){
this.redisTemplate = redisTemplate;
}
@PostConstruct
private void init(){
hashOperations = redisTemplate.opsForHash();
}
public void add(final Movie movie) {
hashOperations.put(KEY, movie.getId(), movie.getName());
}
public void delete(final String id) {
hashOperations.delete(KEY, id);
}
public Movie findMovie(final String id){
return (Movie) hashOperations.get(KEY, id);
}
public Map<Object, Object> findAllMovies(){
return hashOperations.entries(KEY);
}
}
Let’s take note of the init() method. In this method, we use a function named opsForHash(), which returns the operations performed on hash values bound to the given key. We then use the hashOps, which was defined in init(), for all of our CRUD operations.
Web Interface
In this section, we will review adding Redis CRUD operations capabilities to a web interface.
Add a Movie
We want to be able to add a Movie to our web page. The Key is the is the Movie id and the Value is the actual object. However, we will later address this, so only the Movie name is shown as the value.
Let’s add a form to an HTML document and assign appropriate names and IDs:
<form id="addForm">
<div class="form-group">
<label for="keyInput">Movie ID (key)</label>
<input name="keyInput" id="keyInput" class="form-control"/>
</div>
<div class="form-group">
<label for="valueInput">Movie Name (field of Movie object value)</label>
<input name="valueInput" id="valueInput" class="form-control"/>
</div>
<button class="btn btn-default" id="addButton">Add</button>
</form>
Now, we use JavaScript to persist the values on form submission:
$(document).ready(function() {
var keyInput = $('#keyInput'),
valueInput = $('#valueInput');
refreshTable();
$('#addForm').on('submit', function(event) {
var data = {
key: keyInput.val(),
value: valueInput.val()
};
$.post('/add', data, function() {
refreshTable();
keyInput.val('');
valueInput.val('');
keyInput.focus();
});
event.preventDefault();
});
keyInput.focus();
});
We assign the @RequestMapping value for the POST request, request the Key and Value, create a Movie object, and save it to the repository:
@RequestMapping(value = "/add", method = RequestMethod.POST)
public ResponseEntity<String> add(
@RequestParam String key,
@RequestParam String value) {
Movie movie = new Movie(key, value);
redisRepository.add(movie);
return new ResponseEntity<>(HttpStatus.OK);
}
Viewing the Content
Once a Movie object is added, we refresh the table to display an updated table. In our JavaScript code block for section 7.1, we called a JavaScript function called refreshTable(). This function performs a GET request to retrieve the current data in the repository:
function refreshTable() {
$.get('/values', function(data) {
var attr,
mainTable = $('#mainTable tbody');
mainTable.empty();
for (attr in data) {
if (data.hasOwnProperty(attr)) {
mainTable.append(row(attr, data[attr]));
}
}
});
}
The GET request is processed by a method named findAll() that retrieves all the Movie objects stored in the repository and then converts the datatype from Map<Object, Object> to Map<String, String>:
@RequestMapping("/values")
public @ResponseBody Map<String, String> findAll() {
Map<Object, Object> aa = redisRepository.findAllMovies();
Map<String, String> map = new HashMap<String, String>();
for(Map.Entry<Object, Object> entry : aa.entrySet()){
String key = (String) entry.getKey();
map.put(key, aa.get(key).toString());
}
return map;
}
Delete a Movie
We write JavaScript to do a POST request to /delete, refresh the table, and set keyboard focus to key input:
function deleteKey(key) {
$.post('/delete', {key: key}, function() {
refreshTable();
$('#keyInput').focus();
});
}
We request the Key and delete the object in the redisRepository based on this key:
@RequestMapping(value = "/delete", method = RequestMethod.POST)
public ResponseEntity<String> delete(@RequestParam String key) {
redisRepository.delete(key);
return new ResponseEntity<>(HttpStatus.OK);
}
8. Demo
Here, we added two movies:
spring data redis add value
Here, we removed one movie:
spring data redis remove value
Conclusion
In this tutorial, we introduced Spring Data Redis and one way of connecting it to a web application to perform CRUD operations.
The source code for the example application is on GitHub.
Topics:
crud, database, redis, spring boot, spring data, tutorial
Published at DZone with permission of Michael Good , DZone MVB. See the original article here.
Opinions expressed by DZone contributors are their own.
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For a Cisco is regarded as the single most commonly well known and also regarded titles in existence to get a selection of enterprises, these testimonials in many cases are well worth reasonably limited that will various other accreditations really dont give ones take-home pay. It has been reported that will wages grows to get Cisco 500-006 professional staff is occasionally over 16% plus in this particular marketplace, exactly who wouldn?¡¥t like to have enable you to produce an supplemental piece of adjust included with the tip of their take-home pay?
2021 Nov 500-006 simulations
Q21. Why would an endpoint stop sending 720p in a call with a Cisco TelePresence MCU?
A. The endpoint Ethernet speed renegotiated at half-duplex.
B. The Cisco TelePresence MCU is using video to receive bit rate optimization to request a lower bandwidth.
C. Another endpoint joined the conference, which brought the conference rate down.
D. Another endpoint failed in its negotiation with the Cisco TelePresence MCU.
Answer:
Q22. Which three directory services can import Cisco TMS users? (Choose three.)
A. Active Directory
B. Active Directory with Kerberos (Secure AD)
C. Novell eDirectory
D. Lightweight Directory Access Protocol
Answer: A,B,D
Explanation:
User Import
C lick Configure to display the Type field
Select the typeof directory server to Import groups and users from:
Active Directory (AD)
Active Directory with Kerberos (secure AD)
LightweightDirectoryAccessProtocol(LDAP)
Q23. What does an endpoint system use to navigate the Auto Attendant menu on the Cisco TelePresence MCU?
A. FECC and DTMF navigation
B. a special remote that came with the Cisco TelePresence MCU
C. only FECC, DTMF is not supported
D. web interface of the endpoint
Answer:
Q24. How many conferencing bridges can a single full-capacity Cisco TelePresence Conductor support?
A. 1
B. 10
C. 15
D. 25
E. 30
F. 104
G. 500
H. 2400
Answer:
Explanation:
Cisco TelePresence Conductor For larger deplyoments, a full-capacity version of Cisco Telepresence Conductor is required. Up to 2400 concurrent call sessions or up to 30 Cisco Telepresence Servers or
Telepresence MCUs are supported by one full-capacity Cisco Telepresence Conductor appliance or cluster.
Up to three full-capacity Cisco Telepresence Conductors can be clustered to provide resilience.
Q25. Which statement is correct about the configuration of the call control device?
A. The Cisco TelePresence Management Suite can auto-provision the dial plan between the Cisco VCS and Cisco Unified Communications Manager, using CDP.
B. The Cisco Unified Communications Manager dial plan only supports numeric values.
C. The Cisco VCS and Cisco Unified Communications Manager can pass dial plan information between them to create a single directory based on an H.350 schema.
D. The Cisco VCS and Cisco Unified Communications Manager support numeric and URI dialing.
Answer:
Explanation:
CDP: Cisco Discovery Protocol http://en.wikipedia.org/wiki/Cisco_Discovery_Protocol CUCM supports URI dialing since version 9.0H.350: No reference to CUCM in VCS X8.2 Admin Guide.
Update 500-006 exams:
Q26. How will FindMe . help a user working from either home or the office?
A. Anyone can contact the user using a single identity.
B. Users can locate any individual in the company using the address book.
C. Users can change their system names according to their current location.
D. Anyone can contact the user by giving each endpoint the same configuration.
Answer:
Explanation:
FindMe. FindMe is a form of User Policy, which is the set of rules that determines what happens to a call for a particular user or group when it is received by the VCS. The FindMe feature lets you assign a single FindMe ID to individuals or teams in your enterprise. By logging into their FindMe account, users can set up a list of locations such as "at home" or "in the office" and associate their devices with those locations. They can then specify which devices are called when their FindMe ID is dialed, and what happens if those devices are busy or go unanswered. Each user can specify up to 15 devices and 10 locations. This means that potential callers can be given a single FindMe alias on which they can contact an individual or group in your enterprise — callers won't have to know details of all the devices on which that person or group might be available. To enable this feature you must purchase and install the FindMe option key. Standard operation is to use the VCS's own FindMe manager. However you can use an off-box FindMe manager; this feature is intended for future third-party integration.
Q27. The following Cisco TMS warning is displayed: "No route possible between X and Y." What does this warning indicate?
A. One of the endpoints.is not registered.on the Cisco TP VCS.
B. There is a restriction that does not allow calls between zones.
C. TMS cannot find one of the selected systems.
D. Gateway is not available.
Answer:
Q28. Where do you change the Maximum Session Bit Rate for Video Calls?
A. Device > Trunk
B. System > Location
C. Media Resources > Media Resource Group
D. System > Enterprise Parameters
E. System > Region
Answer:
Explanation:
C:UsersMCSDesktop1.jpg
Q29. Which three endpoints are provisioned by Cisco TMSPE? (Choose three.)
A. Cisco TelePresence System MX Series
B. Cisco TelePresence System EX Series
C. Cisco Unified IP Phone 9971
D. Cisco Unified IP Phone 7960
E. Cisco TelePresence System CTS 500
Answer: A,B,E
Explanation:
C:UsersMCSDesktop1.jpg
Q30. Which persistent setting other than system name, E.164 alias, and H.323 ID is configurable for a personal video system?
A. SIP URI
B. MAC address
C. serial number
D. IP address
Answer:
Explanation:
There are four persistent settings:
System Name
H.323ID
E.164 alias
SIP URI
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Erectile Dysfunction and Its Link to Sleep Disorders
Erectile
and Health
Erectile dysfunction (ED) is a common male sexual health problem and a major concern for many men. ED is a condition where a man cannot achieve or maintain an erection during sexual activity. It affects up to 30 million men in the United States and is estimated to affect up to 52% of all men over 40 years of age. Recent studies have revealed a strong link between ED and sleep disorders, such assleep apnea, insomnia, and narcolepsy.
Sleep Apnea
Sleep apnea is a disorder in which a person’s breathing pauses multiple times during sleep and can last up to 10 seconds at a time. It can cause restless sleep and can lead to serious health issues such as heart problems, stroke, and high blood pressure. It can also lead to ED. Several studies have found a significant correlation between sleep apnea and erectile dysfunction. In one study, men with sleep apnea were found to have double the rate of erectile dysfunction compared to men without sleep apnea.
See also The Impact of Testosterone Replacement Therapy on Sexual Health and Libido
Insomnia
Insomnia is defined as difficulty falling and staying asleep. It can cause fatigue, mood swings, and mental health issues. Studies have found that men with chronic insomnia have a three-fold increased risk of developing ED. This is because insomnia disrupts testosterone production, which plays an important role in male sexual health and sexual performance.
See also low testosterone in men
Narcolepsy
Narcolepsy is a sleep disorder which causes excessive fatigue and daytime sleepiness. It can also lead to difficulty with sexual arousal and erection. In one study, men with narcolepsy were found to have a six-fold increased risk of ED compared to the general population.
How to Reduce the Risk of ED
Given the link between sleep disorders and ED, it is important for men to take steps to reduce the risk of erectile dysfunction. The most important step is to get a good night’s sleep each night. This means sticking to a consistent sleep schedule and avoiding things that can disrupt sleep, such as caffeine, alcohol, and electronics. For men who are struggling with a sleep disorder, it is important to seek help from a medical professional. Additionally, eating a healthy diet, exercising regularly, and avoiding smoking can also help reduce the risk of ED.
See also Low Testosterone and Its Impact on Muscle Mass and Strength
Conclusion
Erectile Dysfunction is a common problem that affects many men. Recent studies have revealed a strong link between ED and sleep disorders, such as sleep apnea, insomnia, and narcolepsy. It is important for men to take steps to reduce their risk of ED and seek help from a medical professional if they are suffering from a sleep disorder.
Keywords: Erectile Dysfunction, ED, Sleep Disorders, Sleep Apnea, Insomnia, Narcolepsy, Testosterone, Sexual Health, Sexual Performance.
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Web Attacks and Countermeasures
Web Attacks and Defense
1. Introduction
What is a web application? Why web applications are the first target for hackers? What are the attacks Web applications usually face, how to prevent from these attacks. Lets start from the various web application attacks. This article is divided into three areas including types of attacks, countermeasures and risk factor.
2. ATTACKS
Following are the most common web application attacks.
a. Remote code execution
b. SQL injection
c. Format string vulnerabilities
d. Cross Site Scripting (XSS)
e. Username enumeration
Remote Code Execution
As the name suggests, this vulnerability allows an attacker to run arbitrary, system level code on the vulnerable web application server and retrieve any desired information contained therein. Improper coding errors lead to this vulnerability. At times, it is difficult to discover this vulnerability during penetration testing assignments but such problems are often revealed while doing a source code review. However, when testing Web applications is important to remember that exploitation of this vulnerability can lead to total system compromise with the same rights as the Web server itself is running with.
SQL Injection
SQL injection is a very old approach but it’s still popular among attackers. This technique allows an attacker to retrieve crucial information from a Web server’s database. Depending on the application’s security measures, the impact of this attack can vary from basic information disclosure to remote code execution and total system compromise.
Format String Vulnerabilities
This vulnerability results from the use of unfiltered user input as the format string parameter in certain Perl or C functions that perform formatting, such as C’s printf().
A malicious user may use the %s and %x format tokens, among others, to print data from the stack or possibly other locations in memory. One may also write arbitrary data to arbitrary locations using the %n format token, which commands printf() and similar functions to write back the number of bytes formatted. This is assuming that the corresponding argument exists and is of type int *.
Format string vulnerability attacks fall into three general categories: denial of service, reading and writing.
Cross Site Scripting
The success of this attack requires the victim to execute a malicious URL which may be crafted in such a manner to appear to be legitimate at first look. When visiting such a crafted URL, an attacker can effectively execute something malicious in the victim’s browser. Some malicious JavaScript, for example, will be run in the context of the web site which possesses the XSS bug.
Username enumeration
Username enumeration is a type of attack where the backend validation script tells the attacker if the supplied username is correct or not. Exploiting this vulnerability helps the attacker to experiment with different usernames and determine valid ones with the help of these different error messages.
3. Countermeasures
Username enumerations:
Display consistent error messages to prevent disclosure of valid usernames. Make sure if trivial accounts have been created for testing purposes that their passwords are either not trivial or these accounts are absolutely removed after testing is over – and before the application is put online.
Cross site scripting:
Input validation, secure programming and usage of good language for dynamic web applications.
SQL Injection:
Avoid connecting to the database as a super user or as the database owner. Always use customized database users with the bare minimum required privileges required to perform the assigned task. Perform input validation and do not give error response on client side.
Format String:
Edit the source code so that the input is properly verified.
Remote code execution:
It is an absolute must to sanitize all user input before processing it. As far as possible, avoid using shell commands. However, if they are required, ensure that only filtered data is used to construct the string to be executed and make sure to escape the output
4. Risk Factors
SQL Injection:
Rating: Moderate to Highly Critical
Remote Code Execution:
Rating: Highly Critical
Cross Site Scripting:
Rating: Less Critical
User Name Enumeration
Rating: Less
5. Summary
This is the short article to develop awareness on web attacks and countermeasures, these are common web application attacks.
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Feedback
Projection-based model order reduction for aerodynamic applications
GND
1042925267
Affiliation/Institute
Institut Computational Mathematics
Vendl, Alexander
The subject of this thesis is model order reduction for the governing equations arising in computational fluid dynamics (CFD). Although the application of numerical simulations gains in importance compared to experimental wind tunnel tests, the large amount of time needed for the vast number of computations limits the applicability. As a result efficient computational methods, such as model order reduction, play an important role. The goal of model order reduction is to reduce the number of equations of the underlying system. The reduced order model should then have the property that it can be solved much more efficiently. The challenge of the application to nonlinear equations like the governing equations of CFD is that, although the number of discretized equations can easily be reduced by projection, an independence from the full order is not actually achieved. This is due to the fact that in each iterative step of solving the reduced model, a nonlinear right hand side has to be evaluated, which is of the order of the original model. As a result nonlinear model order reduction methods aim at creating reduced order models, which do not evaluate the right hand side of the governing equations at each and every computational grid point, but only at a small subset of these points. In this work a method called missing point estimation is used. It achieves the above goal with an appropriate projection. Furthermore, due to the projection onto a low-dimensional subspace, the number of equations is significantly reduced compared to the original problem. This altogether yields a reduced order model, which can be solved efficiently. When applying missing point estimation to different fields of application, the selection of the points differs considerably. In this work it shall be investigated, which point selections are most suitable for the prediction of the flow fields around airfoils and complex three-dimensional aircraft configurations.
Diese Arbeit hat die Modellreduktion der Grundgleichungen der Strömungsmechanik zum Thema. Obwohl der Einsatz der numerischen Strömungssimulation gegenüber experimentellen Tests im Windkanal an Bedeutung gewinnt, schränkt der hohe zeitliche Aufwand für die große Anzahl der benötigten Berechnungen die Anwendbarkeit ein. Daher spielen effiziente Berechnungsmethoden wie die Modellreduktion eine wichtige Rolle. Die Modellreduktion hat zum Ziel, die Anzahl der Gleichungen des Systems zu reduzieren. Das Modell reduzierter Ordnung sollte dann die Eigenschaft haben, dass es sich deutlich effizienter lösen lässt. Die Herausforderung bei der Anwendung auf nichtlineare Gleichungen wie denen der Strömungsmechanik besteht darin, dass obwohl die Anzahl der Gleichungen durch Projektion stark reduziert werden können, keine Unabhängigkeit von der Ordnung des Ausgangsproblems erreicht wird. Dies liegt daran, dass in jedem Schritt zur Lösung des reduzierten Modells die rechte Seite des ursprünglichen Systems ausgewertet wird, die von der Ordnung des Ausgangsproblems ist. Daher ist das Ziel, reduzierte Modelle so zu erstellen, dass die rechte Seite nicht an jedem Punkt des Rechengitters, sondern an einer Teilmenge dieser Punkte ausgewertet wird. In dieser Arbeit wird eine Methode namens Missing Point Estimation (MPE) verwendet, die das obige Ziel mit Hilfe einer geeigneten Projektion erreicht. Aufgrund dessen, dass auf einen niedrig-dimensionalen Unterraum projiziert wird, ist zudem die Anzahl der Gleichungen stark gegenüber derjenigen des Ausgangsproblems reduziert. Dies hat dann insgesamt zur Folge, dass sich das reduzierte Modell effizient lösen lässt. Bei der Verwendung der MPE für unterschiedliche Anwendungsgebiete ist die Auswahl der Punkte, an denen die rechte Seite des Systems evaluiert wird, sehr verschieden. In dieser Arbeit soll untersucht werden, welche Auswahlen sich für die Vorhersage von Strömungen um Tragflächenprofile und um komplexe 3D-Konfigurationen eignen.
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Drugs Used In Thromboembolic Disorders Flashcards Preview
Cardiovascular Exam I > Drugs Used In Thromboembolic Disorders > Flashcards
Flashcards in Drugs Used In Thromboembolic Disorders Deck (54)
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1
3 major drug types used in thromboembolic disorders include anticoagulants, antiplatelet drugs, and thrombolytic (fibinolytic) drugs. There are two types of anticoagulants, parenteral or oral. What are the parenteral anticoagulants?
Indirect thrombin and factor Xa (FXa) inhibitors: unfractionated heparin (heparin sodium), low molecular weight heparin (enoxaparin, tinzaparin, dalteparin), and synthetic pentasaccharide (fondaparinux)
Direct thrombin inhibitors: lepirudin, bivalirudin, argatroban
2
3 major drug types used in thromboembolic disorders include anticoagulants, antiplatelet drugs, and thrombolytic (fibinolytic) drugs. There are two types of anticoagulants, parenteral or oral. What are the oral anticoagulants?
Coumarin anticoagulants: warfarin
Direct oral anticoagulants (DOAC): factor Xa inhibitors (rivaroxaban, apixaban, edoxaban), direct thrombin inhibitor (dabigatran)
3
3 major drug types used in thromboembolic disorders include anticoagulants, antiplatelet drugs, and thrombolytic (fibinolytic) drugs. There are two types of anticoagulants, parenteral or oral. What are the antiplatelet drug families?
Inhibitors of thromboxane A2 synthesis:
Aspirin
ADP receptor blockers:
Clopidogrel
Prasugrel
Ticlopidine
Ticagrelor
Platelet glycoprotein receptor blockers:
Abciximab
Eptifibatide
Tirofiban
Inhibitors of phosphodiesterases:
Dipyridamole
Cilostazol
4
3 major drug types used in thromboembolic disorders include anticoagulants, antiplatelet drugs, and thrombolytic (fibinolytic) drugs. There are two types of anticoagulants, parenteral or oral. What are the thrombolytic drug classes?
Tissue-type plasminogen activator drugs:
Alteplase
Reteplase
Tenecteplase
Urokinase-type plasminogen activator:
Urokinase
Streptokinase preparations:
Streptokinase
5
Which category of drugs is primarily used to prevent clots from forming in the arteries (aka white thrombi)?
Antiplatelet drugs
6
Which category of drugs is primarily used to prevent clots from forming in the venous system and heart (red thrombi)?
Anticoagulants
7
MOA of indirect thrombin and FXa inhibitors
Indirect thrombin and factor Xa (FXa) inhibitors: unfractionated heparin (heparin sodium), low molecular weight heparin (enoxaparin, tinzaparin, dalteparin), and synthetic pentasaccharide (fondaparinux)
Bind plasma serine protease inhibitor ANTITHROMBIN III
Antithrombin III inhibits several clotting factor proteases, especially thrombin IIa, IXa, and Xa
8
In the absence of _______, protease inhibition reactions are slow, when it is present it increases antithrombin III activity by 1000-fold
Heparin
9
MOA of high molecular weight heparin vs. low molecular weight heparin vs. fondaparinux
HMW heparin = inhibits the activity of both thrombin and factor Xa
LMW heparin inhibits factor Xa with little effect on thrombin
Fondaparinux inhibits factor Xa activity with no effect on thrombin
10
Clinical use of HMW vs. LMW heparin
They have practically equal efficiency in several thromboembolic conditions
LMW have increased bioavailability from the SC injection site and allow for less frequent injections and more predictable dosing
[note they are very hydrophilic and must be given IV or SC]
Used to tx disorders secondary to red (fibrin-rich) thrombi and reduce the risk of emboli — protects against embolic stroke and PE, given to pts with DVT and atrial arrhythmias, prevention of emboli during surgery, heparin locks prevent clots from forming in catheters
11
Describe monitoring of pts on heparin
Activated partial thromboplastin time (aPTT) — measures the efficacy of the intrinsic (contact activation) pathway and a common pathway. In order to activate the intrinsic pathway, phospholipids, activator, and Ca are mixed with pts plasma — evaluates serine protease factors (II, IX, X, XI, XII) affected by heparin
Anti-Xa assay — designed to examine proteolytic activity of factor Xa
12
Adverse effects of heparin
Bleeding
Heparin-induced thrombocytopenia (HIT) — systemic hypercoagulable state d/t immunogenicity of the complex of heparin with platelet factor 4 (PF4); characterized by venous and arterial thromboses
13
Contraindications and methods for reversal of heparin
Contraindications: severe HTN, active TB, ulcers of GI tract, pts with recent surgeries
Reversal of heparin: protamine sulfate
14
MOA of fondaparinux
Binds to antithrombin to indirectly inhibit factor Xa
[High affinity reversible finding to antithrombin III; conformational change in the reactive loop greatly enhances antithrombin basal rate of factor Xa inactivation; thus fondaparinux acts a an antithrombin III catalyst]
15
T/F: unlike heparins, fondaparinux does not inhibit thrombin activity, rarely induces HIT, and is not reversed by protamine sulfate
True
16
Clinical indications for fondaparinux use
Prevention of DVT
Tx of acute DVT (in conjunction with warfarin)
Tx of PE
17
MOA of parenteral direct thrombin inhibitors
[Direct thrombin inhibitors: lepirudin, bivalirudin, argatroban]
Direct inhibition of the protease activity of thrombin
Lepirudin and bivalirudin are bivalent direct thrombin inhibitors (bind at both active site and substrate recognition site)
Argatroban binds only at the thrombin active site (small molecular weight inhibitor; short-acting drug — used IV)
18
Classify lepirudin and bivalirudin in terms of reversible vs. irreversible inhibition of thrombin
Lepirudin = irreversible inhibitor of thrombin
Bivalirudin = reversible inhibitor of thrombin; also inhibits platelet aggregation
19
Clinical indications and AEs for the direct thrombin inhibitors
[Direct thrombin inhibitors: lepirudin, bivalirudin, argatroban]
Indications: HIT, coronary angioplasty (bivalirudin and argatroban)
AEs: bleeding (no antidote exists!), repeated lepirudin use may cause anaphylactic reaction
20
Warfarin is the most commonly prescribed AC in the US. What is its MOA?
Inhibits reactivation of vitamin K, by inhibiting enzyme vitamin K epoxide reductase
Inhibits carboxylation of glutamate residues by gamma-glutamyl carboxylase (GGCX) in prothrombin and factors VII, IX, and X, making them inactive
21
List proteins affected by warfarin
Factor II (prothrombin)
Hemostatic factors VII, IX, and X
Other proteins that affect function in apoptosis, bone ossification, ECM formation, etc.
Note: carboxylation fo glutamate residues is one of the common mechanisms of posttranslational modification of proteins — converts hypofunctional hemostatic factors into functional ones
22
Describe potency and metabolism of the warfarin isomers
2 stereoisomers: R and S
S-isomer is 3-5x more potent
R-warfarin is metabolized by CYP3A4 and some other CYP isoforms
S-warfarin is metabolized primarily by CYP2C9
[OH-derivatives are pumped out of hepatocytes by ABCB1 transporter into bile and excreted with the bile]
23
T/F: warfarin has low bioavailability, short half life, and dosage is relatively consistent among pts
False!
Warfarin has 100% bioavailability, delayed onset of action, long half life (36h), and the correct dose varies widely from pt to pt based on disease state, genetic makeup, and drug interactions
24
Clinical use and AEs of Warfarin
Clinical use: prevent thrombosis or prevent/tx thromboembolism, atrial fibrillation, prosthetic heart valves
AEs: teratogenic effect (bleeding d/o in fetus, abnormal bone formation), skin necrosis, infarction of breasts, intestines, extremities; osteoporosis, bleeding
25
Warfarin dose is titrated based on what lab tests?
Prothrombin time (PT) — time to coagulation of plasma after addition of tissue factor (factor III); used for evaluation of extrinsic path
INR = international normalized ratio; 0.9 to 1.3 is normal, 0.5 has high chance of thrombosis, 4-5 has high chance of bleeding, 2-3 is the range for pts on warfarin
26
Pharmacogenomics affecting variability in warfarin action
VKORC1 — responsible for 30% variation in dose. High dose haplotype more common in african americans (more resistant to warfarin); Low dose haplotype more common in asian americans (less resistant to warfarin)
CYP2C9 — responsible for 10% variation in dose, mainly among caucasian pts
27
Pharmacokinetic factors that increase prothrombin time d/t interactions with warfarin
Amiodarone
Cimetidine
Disulfuram
Metronidazole*
Fluconazole*
Phenylbutazone*
Sulfinpyrazone*
TMP-SMX
[* = specific to S-warfarin]
28
Pharmacodynamic factors that increase prothrombin time d/t interactions with warfarin
Drugs:
High dose ASA
3rd gen. Cephalosporins
Heparin
Other factors:
Hepatic dz (red.clotting factor synth)
Hyperthryoidism
29
Pharmacokinetic factors that decrease prothrombin time d/t interactions with warfarin
Barbiturates
Cholestyramine
Rifampin
30
Pharmacodynamic factors that decrease prothrombin time d/t interactions with warfarin
Drugs:
Diuretics
Vitamin K
Other factors:
Hypothyroidism
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Expert Knowledge Trivia Quiz
Link to Expert Knowledge Quiz title page
Current score: 0/10 View Scoring Summary
4. Confronting one’s sphere
In 1959, physicist Freeman Dyson described a concept that came to be known as a “Dyson Sphere”. A Dyson Sphere is:
A) The minimum volume needed to contain all living things
B) A personal vehicle for interstellar travel
C) The region of influence of an interstellar empire
D) A rigid hollow sphere completely enclosing a star
Your answer — A) The minimum volume needed to contain all living things — was incorrect.
When considering the long-term consequences of continually increasing energy consumption, Dyson foresaw that in the distant future humanity would require energy in amounts that now seem almost incalculably vast. He proposed a correspondingly vast solution: a shell with a radius of one earth orbit, completely enclosing the sun, which would capture all the sun’s energy for human use.
Click “Question 5” below to continue the quiz.
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Issue No.08 - August (2000 vol.11)
pp: 794-812
ABSTRACT
<p><b>Abstract</b>—Multidestination message passing has been proposed as an attractive mechanism for efficiently implementing multicast and other collective operations on direct networks. However, applying this mechanism to switch-based parallel systems is nontrivial. In this paper, we propose alternative switch architectures with differing buffer organizations to implement multidestination worms on switch-based parallel systems. First, we discuss issues related to such implementation (deadlock-freedom, replication mechanisms, header encoding, and routing). Next, we demonstrate how an existing central-buffer-based switch architecture supporting unicast message passing can be enhanced to accommodate multidestination message passing. Similarly, implementing multidestination worms on an input-buffer-based switch architecture is discussed, and two architectural alternatives are presented that reduce the wiring complexity in a practical switch implementation. The central-buffer-based and input-buffer-based implementations are evaluated against each other, as well as against the corresponding software-based schemes. Simulation experiments under a range of traffic (multiple multicast, bimodal, varying degree of multicast, and message length) and system size are used for evaluation. The study demonstrates the superiority of the central-buffer-based switch architecture. It also indicates that under bimodal traffic the central-buffer-based hardware multicast implementation affects background unicast traffic less adversely compared to a software-based multicast implementation. These results show that multidestination message passing can be applied easily and effectively to switch-based parallel systems to deliver good multicast and collective communication performance.</p>
INDEX TERMS
Parallel computer architecture, switch/router architecture, wormhole switching, cut-through switching, multicast, broadcast, collective communication, interconnection networks, performance evaluation.
CITATION
Rajeev Sivaram, Craig B. Stunkel, Dhabaleswar K. Panda, "Implementing Multidestination Worms in Switch-Based Parallel Systems: Architectural Alternatives and Their Impact", IEEE Transactions on Parallel & Distributed Systems, vol.11, no. 8, pp. 794-812, August 2000, doi:10.1109/71.877938
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ASP.NET Razor Code Expressions
Razor syntax is widely used with C# programming language. To write C# code into a view use @ (at) sign to start Razor syntax. We can use it to write single line expression or multiline code block. Let's see how we can use C# code in the view page.
The following example demonstrate code expression.
// Index.cshtml
Produce the following output.
Output:
ASP Razor code expression 1
Implicit Razor Expressions
Implicit Razor expression starts with @ (at) character followed by C# code. The following example demonstrates about implicit expressions.
// Index.cshtml
It produces the following output.
Output:
ASP Razor code expression 2
Explicit Razor Expressions
Explicit Razor expression consists of @ (at) character with balanced parenthesis. In the following example, expression is enclosed with parenthesis to execute safely. It will throw an error if it is not enclosed with parenthesis.
We can use explicit expression to concatenate text with an expression.
// Index.cshtml
It produces the following output.
Output:
ASP Razor code expression 3
Razor Expression Encoding
Razor provides expression encoding to avoid malicious code and security risks. In case, if user enters a malicious script as input, razor engine encode the script and render as HTML output.
Here, we are not using razor syntax in view page.
// Index.cshtml
It produces the following output.
Output:
ASP Razor code expression 4
In the following example, we are encoding JavaScript script.
// Index.cshtml
Now, it produces the following output.
Output:
ASP Razor code expression 5
This time razor engine encodes the script and return as a simple HTML string.
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Flotation equipment is binq made excellent mining crushing machinery, we offer you the best of the equipment and services . . .
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Gravity Flotation and Dissolved Air Flotation
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Gravity Flotation
Gravity flotation is used, sometimes in combination with sedimentation and sometimes alone, to remove oils, greases, and other flotables such as solids that have a low specific weight. Various types of “skimmers” have been developed to harvest floated materials, and the collection device to which the skimmers transport these materials must be properly designed. Figures 8-98(a)–(f) are photographs of different types of gravity flotation and harvesting equipment.
Dissolved Air Flotation
Dissolved air flotation (DAF) is a solids separation process, similar to plain sedimentation. The force that drives DAF is gravity, and the force that retards the process is hydrodynamic drag. Dissolved air flotation involves the use of pressure to dissolve more air into wastewater than can be dissolved under normal atmospheric pressure, then releasing the pressure. The “dissolved” air, now in a supersaturated state, comes out of solution, or “precipitates,” in the form of tiny bubbles. As these tiny bubbles form, they become attached to solid particles within the wastewater, driven by their hydrophobic nature. When sufficient air bubbles attach to a particle to make the conglomerate (particle plus air bubbles) lighter than water (specific gravity less than one), the particle is carried to the water surface.
A familiar example of this phenomenon is a straw in a freshly opened bottle of a carbonated beverage. Before the bottle is opened, its contents are under pressure, having been pressurized with carbon dioxide gas at the time of bottling. When the cap is taken off, the pressure is released, and carbon dioxide precipitates from solution in the form of small bubbles. The bubbles attach to any solid surface, including a straw, if one has been placed in the bottle. Soon, the straw rises up in the bottle.
In a manner similar to the straw, solids having a specific gravity greater than one can be caused to rise to the surface of a volume of wastewater. Solids having a specific gravity less than one can also be caused to rise to the surface at a faster rate by using DAF than without it. Often, chemical coagulation of the solids can significantly enhance the process, and in some cases, dissolved solids can be precipitated, chemically, then separated from the bulk solution by DAF.
“Dissolution” of Air in Water Examination of the molecular structures of both oxygen and nitrogen reveals that neither would be expected to be polar, therefore, neither would be expected to be soluble in water.
Dalton’s law of partial pressures states further that, in a mixture of gases, each gas exerts pressure independently of the others, and the pressure exerted by each individual gas, referred to as its “partial pressure,” is the same as it would be if it were the only gas in the entire volume. The pressure exerted by the mixture, therefore, is the sum of all the partial pressures. Conversely, the partial pressure of any individual gas in a mixture, such as air, is equal to the pressure of the mixture multiplied by the fraction, by volume, of that gas in the mixture.
The consequence of this equation is that, by way of the process of diffusion, molecules of any gas, in contact with a given volume of water, will diffuse into that volume to an extent that is described by Henry’s Law, as long as the quantity of dissolved gas is relatively small. For higher concentrations, Henry’s constant changes somewhat. This principle holds for any substance in the gaseous state, including volatilized organics. The molecules that are forced into the water by this diffusion process exhibit properties that are essentially identical to those that are truly dissolved. In conformance with the second law of thermodynamics, they distribute themselves uniformly throughout the liquid volume (maximum disorganization), and they will react with substances that are dissolved.
An example is the reaction of molecular oxygen with ferrous ions. Unlike dissolved substances, however, they will be replenished from the gas phase with which they are in contact, up to the extent described by Henry’s law, if they are depleted by way of reaction with other substances, or by biological metabolism. The difference between a substance existing in water solution as the result of diffusion and one that is truly dissolved can be illustrated by the following example.
Consider a beaker of water in a closed space—a small, airtight room, for instance. An amount of sodium chloride is dissolved in the water, and the water is saturated with oxygen; that is, it is in equilibrium with the air in the closed space. Now, a container of sodium chloride is opened, and at the same time, a pressurized cylinder of oxygen is released.
The concentration of sodium chloride will not change, but, because the quantity of oxygen in the air within the closed space increases (partial pressure of oxygen increases), the concentration of dissolved oxygen in the water increases. The oxygen molecules are not truly dissolved; that is, they are not held in solution by the forces of solvation, or hydrogen bonding by the water molecules. Rather, they are forced into the volume of water by diffusion, which is to say, by the second law of thermodynamics. The molecules of gas are constantly passing through the water-air interface in both directions. Those that are in the water are constantly breaking through the surface to return to the gas phase, and they are continually being replaced by diffusion from the air into the water. An equilibrium concentration becomes established, described by Henry’s law. All species of gas that happen to exist in the “air” participate in this process: nitrogen, oxygen, water vapor, volatilized organics, or whatever other gases are included in the given volume of air.
The concentration, in terms of mass of any particular gas that will be forced into the water phase until equilibrium becomes established, depends on the temperature and the concentration of dissolved substances such as salts and the “partial pressure” of the gas in the gas phase.
As the temperature of the water increases, the random vibration activity, “Brownian motion,” of the water increases. This results in less room between water molecules for the molecules of gas to “fit into.” The result is that the equilibrium concentration of the gas decreases. This is opposite to the effect of temperature on dissolution of truly soluble substances in water, or other liquids, where increasing temperature results in increasing solubility.
Some gasses are truly soluble in water because their molecules are polar, and these gases exhibit behavior of both solubility and diffusivity. Carbon dioxide and hydrogen sulfide are examples. As the temperature of water increases, solubility increases, but diffusivity decreases. Also, because each of these two gases exists in equilibrium with hydrogen ion when in water solution, the pH of the water medium has a dominant effect on their solubility, or rather, their equilibrium concentration, in water.
In the previous example, where a beaker of water is in a closed space, if a flame burning in the closed space depletes the oxygen in the air, oxygen will come out of the water solution. If all of the oxygen is removed from the air, the concentration of “dissolved oxygen” in the beaker of water will eventually go to zero (or close to it), and the time of this occurrence will coincide with the flame extinguishing because of lack of oxygen in the air.
Dissolved Air Flotation Equipment The dissolved air flotation (DAF) process takes advantage of the principles described earlier. Figure 8-99 presents a diagram of a DAF system, complete with chemical coagulation and sludge handling equipment. As shown in Figure 8-99, raw (or pretreated) wastewater receives a dose of a chemical coagulant (metal salt, for instance), then proceeds to a coagulation-flocculation tank. After coagulation of the target substances, the mixture is conveyed to the flotation tank, where it is released in the presence of recycled effluent that has just been saturated with air under several atmospheres of pressure in the pressurization system shown. An anionic polymer (coagulant aid) is injected into the coagulated wastewater just as it enters the flotation tank.
The recycled effluent is saturated with air under pressure as follows: A suitable centrifugal pump forces a portion of the treated effluent into a pressure-holding tank. A valve at the outlet from the pressure-holding tank regulates the pressure in the tank, the flow rate through the tank, and the retention time in the tank, simultaneously. An air compressor maintains an appropriate flow of air into the pressure-holding tank. Under the pressure in the tank, air from the compressor is diffused into the water to a concentration higher than its saturation value under normal atmospheric pressure. In other words, about 23 ppm of “air” (nitrogen plus oxygen) can be “dissolved” in water under normal atmospheric pressure (14.7 psig). At a pressure of six atmospheres, for instance, (6 × 14.7 = about 90 psig), Henry’s law would predict that about 6 × 23, or about 130 ppm, of air can be diffused into the water.
In practice, dissolution of air into the water in the pressurized holding tank is less than 100% efficient, and a correction factor, f, which varies between 0.5 and 0.8, is used to calculate the actual concentration.
After being held in the pressure-holding tank in the presence of pressurized air, the recycled effluent is released at the bottom of the flotation tank, in close proximity to where the coagulated wastewater is being released. The pressure to which the recycled effluent is subjected has now been reduced to one atmosphere, plus the pressure caused by the depth of water in the flotation tank. Here, the “solubility” of the air is less, by a factor of slightly less than the number of atmospheres of pressure in the pressurization system, but the quantity of water available for the air to diffuse into has increased by a factor equal to the inverse of the recycle ratio.
Practically, however, the wastewater will already be saturated with respect to nitrogen but may have no oxygen because of biological activity. Therefore, the “solubility” of air at the bottom of the flotation tank is about 25 ppm, and the excess air from the pressurized, recycled effluent precipitates from “solution.” As this air precipitates in the form of tiny, almost microscopic, bubbles, the bubbles attach to the coagulated solids. The presence of the anionic polymer (coagulant aid), plus the continued action of the coagulant, causes the building of larger solid conglomerates, entrapping many of the adsorbed air bubbles. The net effect is that the solids are floated to the surface of the flotation tank, where they can be collected by some means, thus removed from the wastewater.
Some DAF systems do not have a pressurized recycle system, but rather, the entire forward flow on its way to the flotation tank is pressurized. This type of DAF is referred to as “direct pressurization” and is not widely used for treating industrial wastewaters because of undesirable shearing of chemical flocs by the pump and valve.
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Documento 16 Ejemplo Regresion
Paquetes necesarios:
# Instalamos devtools y el dataset con el que vamos a trabajar si no lo tenemos aún:
# install.packages("devtools")
# install.packages("GGally")
# devtools::install_github("kassambara/datarium")
library(datarium)
library(dplyr)
library(ggplot2)
library(magrittr)
library(GGally)
• Data marketing: inversión en youtube, facebook y periódicos –> ventas
data("marketing")
16.1 Análisis exploratorio
dim(marketing)
## [1] 200 4
str(marketing)
## 'data.frame': 200 obs. of 4 variables:
## $ youtube : num 276.1 53.4 20.6 181.8 217 ...
## $ facebook : num 45.4 47.2 55.1 49.6 13 ...
## $ newspaper: num 83 54.1 83.2 70.2 70.1 ...
## $ sales : num 26.5 12.5 11.2 22.2 15.5 ...
La función summary() muestra la media, mediana, cuartiles, valor mínimo y valor máximo, para variables cuantitativas y la frecuencia absoluta para variables cualitativas.
Los cuartiles son valores que dividen una muestra de datos en cuatro partes iguales. Utilizando cuartiles puede evaluar rápidamente la dispersión y la tendencia central de un conjunto de datos, que son los pasos iniciales importantes para comprender sus datos.
La manera más simple de medir la dispersión es identificar los valores mayor y menor de un conjunto de datos. La diferencia entre los valores mínimo y máximo se denomina el rango (o recorrido) de las observaciones.
summary(marketing)
## youtube facebook newspaper sales
## Min. : 0.84 Min. : 0.00 Min. : 0.36 Min. : 1.92
## 1st Qu.: 89.25 1st Qu.:11.97 1st Qu.: 15.30 1st Qu.:12.45
## Median :179.70 Median :27.48 Median : 30.90 Median :15.48
## Mean :176.45 Mean :27.92 Mean : 36.66 Mean :16.83
## 3rd Qu.:262.59 3rd Qu.:43.83 3rd Qu.: 54.12 3rd Qu.:20.88
## Max. :355.68 Max. :59.52 Max. :136.80 Max. :32.40
Por ejemplo, vemos que existe mayor dispersión en Youtube (Min: 0.84, Max: 355,68) que en Facebook (Min: 0, Max: 59.52).
quantile(marketing$youtube)
## 0% 25% 50% 75% 100%
## 0.84 89.25 179.70 262.59 355.68
plot(marketing)
ggpairs(marketing)
Podemos apreciar que tanto Youtube como Facebook siguen una relación lineal positiva: esto significa que ambas variables aumentan o disminuyen simultáneamente a un ritmo constante.
• La correlación negativa indica que están asociadas de forma inversa, esto es, valores altos de una de las variables se corresponden con valores bajos de la otra.
# Relación positiva y parece que es lineal:
# Nuestra variable y será la que queramos predecir.
marketing %>%
ggplot(aes(x=youtube, y=sales)) +
geom_point() +
stat_smooth()
## `geom_smooth()` using method = 'loess' and formula 'y ~ x'
marketing %>%
ggplot(aes(x=facebook, y=sales)) +
geom_point() +
stat_smooth()
## `geom_smooth()` using method = 'loess' and formula 'y ~ x'
# No es lineal:
marketing %>%
ggplot(aes(x=newspaper, y=sales)) +
geom_point() +
stat_smooth()
## `geom_smooth()` using method = 'loess' and formula 'y ~ x'
16.2 Correlación:
Segunda forma para sacar la correlación (aparte de verlo visualmente con ggpairs):
# Hay que explicar el significado de cada cosa
cor(marketing$sales, marketing$youtube)
## [1] 0.7822244
# Al ser el coeficiente de correlación de 0.78
# podemos afirmar que la correlación es lineal positiva.
La correlación es usada para determinar la relación entre dos o más variables. El Coeficiente de Correlación es un valor cuantitativo de la relación entre dos o más variables, pudiendo variar desde -1.00 hasta 1.00.
La correlación de proporcionalidad directa o positiva se establece con los valores +1.00 y de proporcionalidad inversa o negativa, con -1.00.
No existe relación entre las variables cuando el coeficiente es de 0.00.
16.3 Modelo:
¿Hay relación entre la inversión y las ventas?
La función lm() la utilizamos cuando queremos predecir –o explicar– una variable dependiente a partir de una o más variables independientes.
# Variable depend: Sales // Variables independ: Youtube
ventas_youtube <- lm(data = marketing, formula = sales ~ youtube)
ventas_youtube
##
## Call:
## lm(formula = sales ~ youtube, data = marketing)
##
## Coefficients:
## (Intercept) youtube
## 8.43911 0.04754
plot(marketing$youtube, marketing$sales)
abline(ventas_youtube, col = "red")
Output de lm():
La ordenada al origen (Intercept) y las pendientes estimadas para cada variable.
• Intercept: Término ind de la ecuación de la recta. Se define como el resultado esperado cuando Youtube es cero (ordenada al origen).
• Slope: Pendiente de la recta. Si yo incremento en una unidad la variable Youtube, las ventas van a subir en 0.04754.
• Modelo lineal encontrado?
Ventas = 8.43911 + 0.04754 * youtube Por cada unidad las ventas se incrementan en un 0.04754
ventas_youtube$coefficients
## (Intercept) youtube
## 8.43911226 0.04753664
# coefficients(ventas_youtube)
# ventas_youtube$residuals # Error en cada punto, hay bastantes (200 observaciones)
ventas_youtube$residuals[1] # Cogemos el primero
## 1
## 4.955071
#residuals(ventas_youtube)
ventas_youtube$fitted.values[1:10] # y-aproximado
## 1 2 3 4 5 6 7 8
## 21.564929 10.977569 9.420269 17.081273 18.752662 8.935395 11.719140 15.295797
## 9 10
## 8.929690 19.836497
# ventas_youtube$model[1:10] Para visualizar el modelo
16.4 Dibujar el modelo y el dataset
attach(marketing)
plot(youtube, sales)
abline(ventas_youtube)
# En la Y va la funcion que tu quieres predecir, es decir la ventas
marketing %>%
ggplot(aes(x=youtube, y=sales)) +
geom_point() +
stat_smooth(method = lm)
## `geom_smooth()` using formula 'y ~ x'
16.5 Plot del modelo:
plot(ventas_youtube)
1. Residuos linealmente distribuidos, cerca del y = 0
2. Los residuos están prácticamente distribuidos siguiendo una normal. También detecta outliers y valores importantes.
3. Residuos distribuidos aleatoriamente -> Mucha dispersión de los errores.
4. Distancia Cook –> Outliers, valores importantes.
Ahora, cómo de bueno es el modelo:
Con la función summary() obtenemos los errores estándar de los coeficientes, los p-values así como el estadístico F y R2. En modelos lineales simples (como este caso), dado que solo hay un predictor, el p-value del test F es igual al p-value del t-test del predictor.
summary(ventas_youtube)
##
## Call:
## lm(formula = sales ~ youtube, data = marketing)
##
## Residuals:
## Min 1Q Median 3Q Max
## -10.0632 -2.3454 -0.2295 2.4805 8.6548
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 8.439112 0.549412 15.36 <2e-16 ***
## youtube 0.047537 0.002691 17.67 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 3.91 on 198 degrees of freedom
## Multiple R-squared: 0.6119, Adjusted R-squared: 0.6099
## F-statistic: 312.1 on 1 and 198 DF, p-value: < 2.2e-16
¿Hay modelo? H0 o H1
• H0: no hay modelo, ai=0
• F-estadístico –> 312.1 (muy cerca de 1 - no hay relaciones de dependecia - no hay modelo —> se cumple H0)
• p-value (probabilidad): 2.2e-16 no se cumple H0, H1 es cierta (si hay modelo)
Residuos - Calidad del ajuste realizado - media, dispersión…
R2 - 0.6119 -> 61.19% de la variabilidad de las ventas viene reflejado por la variante youtube.
R2 ajustado -> 60.99%. No está sobrecargado (overfitting)
• Probabilidad Pr(>|t|)
• Pr(>|t|) = <2e-16 *** muy significativo
Si tuviéramos (por ejemplo):
• Pr(>|t|) = 0.13 nada significativo
Entonces, en este caso:
Ventas = 0.04754 * youtube
16.6 Modelo regresión multivariable:
ventas <- lm(data = marketing, sales ~ youtube+facebook+newspaper)
# ventas <- lm(data = marketing, sales ~ .)
ventas
##
## Call:
## lm(formula = sales ~ youtube + facebook + newspaper, data = marketing)
##
## Coefficients:
## (Intercept) youtube facebook newspaper
## 3.526667 0.045765 0.188530 -0.001037
plot(ventas)
summary(ventas)
##
## Call:
## lm(formula = sales ~ youtube + facebook + newspaper, data = marketing)
##
## Residuals:
## Min 1Q Median 3Q Max
## -10.5932 -1.0690 0.2902 1.4272 3.3951
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 3.526667 0.374290 9.422 <2e-16 ***
## youtube 0.045765 0.001395 32.809 <2e-16 ***
## facebook 0.188530 0.008611 21.893 <2e-16 ***
## newspaper -0.001037 0.005871 -0.177 0.86
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 2.023 on 196 degrees of freedom
## Multiple R-squared: 0.8972, Adjusted R-squared: 0.8956
## F-statistic: 570.3 on 3 and 196 DF, p-value: < 2.2e-16
# La probabilidad del newspaper es demasiada alta, nos dice que no es significativa en las ventas. No nos interesa invertir en newspaper.
# Quitaríamos del modelo el newspaper
ventas2 <- lm(data = marketing, sales ~ youtube+facebook)
ventas2
##
## Call:
## lm(formula = sales ~ youtube + facebook, data = marketing)
##
## Coefficients:
## (Intercept) youtube facebook
## 3.50532 0.04575 0.18799
plot(ventas2)
summary(ventas2)
##
## Call:
## lm(formula = sales ~ youtube + facebook, data = marketing)
##
## Residuals:
## Min 1Q Median 3Q Max
## -10.5572 -1.0502 0.2906 1.4049 3.3994
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 3.50532 0.35339 9.919 <2e-16 ***
## youtube 0.04575 0.00139 32.909 <2e-16 ***
## facebook 0.18799 0.00804 23.382 <2e-16 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 2.018 on 197 degrees of freedom
## Multiple R-squared: 0.8972, Adjusted R-squared: 0.8962
## F-statistic: 859.6 on 2 and 197 DF, p-value: < 2.2e-16
16.7 Modelo polinomial:
¿Hay una parabola sales-youtube?
ventas_pol2 <- lm(data = marketing, sales ~ youtube+I(youtube^2))
ventas_pol2
##
## Call:
## lm(formula = sales ~ youtube + I(youtube^2), data = marketing)
##
## Coefficients:
## (Intercept) youtube I(youtube^2)
## 7.337e+00 6.727e-02 -5.706e-05
summary(ventas_pol2)
##
## Call:
## lm(formula = sales ~ youtube + I(youtube^2), data = marketing)
##
## Residuals:
## Min 1Q Median 3Q Max
## -9.2213 -2.1412 -0.1874 2.4106 9.0117
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 7.337e+00 7.911e-01 9.275 < 2e-16 ***
## youtube 6.727e-02 1.059e-02 6.349 1.46e-09 ***
## I(youtube^2) -5.706e-05 2.965e-05 -1.924 0.0557 .
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 3.884 on 197 degrees of freedom
## Multiple R-squared: 0.619, Adjusted R-squared: 0.6152
## F-statistic: 160.1 on 2 and 197 DF, p-value: < 2.2e-16
# Vemos que no ha mejorado mucho
16.8 EJEMPLO INTERNET
Para la salida:
##
## Call:
## lm(formula = ausencias ~ salario, data = df)
##
## Residuals:
## Min 1Q Median 3Q Max
## -9.516 -3.053 1.428 2.961 5.475
##
## Coefficients:
## Estimate Std. Error t value Pr(>|t|)
## (Intercept) 47.6002 3.0789 15.460 9.50e-10 ***
## salario -3.0094 0.4027 -7.474 4.67e-06 ***
## ---
## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
##
## Residual standard error: 4.294 on 13 degrees of freedom
## Multiple R-squared: 0.8112, Adjusted R-squared: 0.7967
## F-statistic: 55.86 on 1 and 13 DF, p-value: 4.672e-06
Interpretación:
El modelo ajustado es significativo: Los coeficientes de regresión son 47.6002 y -3.0094, estos parámetros son significativos, con p-valor menor de 0.05 (9.50e-10, 4.67e-06). El error estándar para cada parámetro es 3.0789 y 0.4027 respectivamente. La R2 ajustada es 0.7967, que indica un buen ajuste del modelo (próximo a 1),
El modelo tiene la forma de:
• ausencias=47.60−3.01×salario
• Los coeficientes de regresión son 47.60 y -3.01.
• 47.60 es el valor medio de la variable dependiente (ausencias) cuando la predictora es cero (salario).
• 3.01 es el efecto medio (negativo) sobre la variable dependiente Y (ausencias) al aumentar en una unidad el valor de la predictora X (salario). Esto es, variación que se produce en Y (-3.01) por cada unidad de incremento en X.
EN CONCLUSIÓN: Existe una relación lineal negativa entre las variables: cuando aumentamos en una unidad el salario, las ausencias disminuyen en 3.01 unidades. De forma que por cada aumento de la categoría del salario, las ausencias de los trabajadores disminuyen en 3.01 días.
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Article Text
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The prevalence, severity and risk factors for pterygium in central Myanmar: the Meiktila Eye Study
1. S R Durkin1,
2. S Abhary1,
3. H S Newland2,
4. D Selva2,
5. T Aung3,
6. R J Casson1
1. 1
South Australian Institute of Ophthalmology, Adelaide, Australia
2. 2
Department of Ophthalmology & Visual Sciences, The University of Adelaide, Adelaide, Australia
3. 3
Yangon Eye Hospital, Yangon, Myanmar
1. Dr S R Durkin, South Australian Institute of Ophthalmology, Ophthalmology Network, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia 5000; shane_durkin{at}yahoo.com
Abstract
Aims: To determine the prevalence, severity and risk factors associated with pterygium in adults in central Myanmar.
Methods: Population-based, cross-sectional survey of the people 40 years and over residing in rural Myanmar. Pterygium was graded for severity (T1 to T3) by visibility of episcleral vessels, and the apical extent was recorded. An autorefractor was used to measure refractive error.
Results: There were 2481 subjects identified, and 2076 (83.7%) participated. The prevalence of pterygium in either eye was 19.6% (95% confidence interval (CI) 16.9 to 22.2) and of bilateral pterygium 8.0% (95% CI 7.7 to 8.3). Outdoor occupation was an independent predictor of pterygium (p<0.01). The mean apical extent from the limbus was 2.2 mm (95% CI 2.05 to 2.35). Higher-grade pterygia did not have a significantly greater apical extent (p = 0.35). The presence of pterygium was associated with astigmatism, (p = 0.01), and the amount of astigmatism increased as both the severity (p<0.01) and apical extent increased (p<0.01). Two people of the 84 people blinded in both eyes were bilaterally blind from pterygium (1.7%; 95% CI 0.2 to 6.1), and pterygium accounted for 2.2% (95% CI 0.7 to 5.0) of blindness in at least one eye. No participant had low vision in both eyes due to pterygium, but pterygium led to 0.8% (95% CI 0.3 to 1.6) of low vision in at least one eye. Pterygium was therefore associated with 0.4% (95% CI 0.04 to 1.3) of binocular visual impairment and 1.0% (95% CI 0.6 to 1.8) of visual impairment in a least one eye.
Conclusions: There is a high prevalence of pterygium in central Myanmar, and the risk of developing this condition increases with outdoor occupation. Pterygium in this population is associated with considerable visual morbidity, including blindness.
Statistics from Altmetric.com
Footnotes
• Funding: The research was supported by a donation from Pfizer, who had no involvement in the analysis or interpretation of results.
• Competing interests: None.
• Patient consent: Informed consent was obtained for publication of figure 1.
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Boost C++ Efficiency Top Performance Tips Unveiled
Boost C++ Efficiency: Top Performance Tips Unveiled
In the fast-paced realm of programming, the need for optimized code is paramount. As a C++ enthusiast, you’re likely familiar with the importance of performance. Let’s delve into the secrets that can turbocharge your C++ code and elevate your programming prowess.
Mastering the Basics: Lay a Solid Foundation
First and foremost, ensure your grasp on the fundamentals is rock-solid. Efficient C++ programming starts with a clear understanding of language basics, syntax, and data structures. Familiarize yourself with the intricacies of memory management, pointers, and smart pointers. A strong foundation sets the stage for high-performance code.
Smart Usage of Containers: Choose Wisely
C++ offers a plethora of container classes, each with its strengths and weaknesses. When optimizing for performance, selecting the right container becomes crucial. Vector, list, map, and unordered_map have distinct use cases. Understand the characteristics of each and employ them judiciously based on your specific requirements.
Const-Correctness: Embrace the Immutable
Embracing const-correctness not only enhances code readability but also contributes to performance improvements. Declare variables and functions as const wherever applicable. This not only communicates intent but also enables the compiler to make certain optimizations, leading to more efficient code execution.
Inline Functions: Unleash the Speed
Inlining functions can be a game-changer for C++ performance. By eliminating the overhead of function calls, you can significantly reduce execution time. However, exercise caution – indiscriminate inlining can lead to code bloat. Identify critical functions and strategically inline them to strike the right balance between speed and code size.
Optimized Memory Usage: Mind Your Footprint
Efficient memory usage is a cornerstone of C++ performance. Be mindful of your data structures and their memory requirements. Choose the smallest data type that meets your needs, and avoid unnecessary dynamic memory allocations. This not only speeds up your program but also minimizes the risk of memory-related issues.
Algorithmic Efficiency: Choose the Right Tool for the Job
C++ boasts a rich set of algorithms in its Standard Template Library (STL). When optimizing for performance, understanding the time complexity of these algorithms is essential. Select algorithms that align with the specific requirements of your task. Choosing the right tool for the job can lead to substantial improvements in execution speed.
Parallelism and Concurrency: Harness the Power
Modern processors often come equipped with multiple cores, and C++ provides mechanisms to harness this parallel processing power. Explore threading and concurrency to break down tasks into parallel units. Be cautious with synchronization to avoid pitfalls, but when employed correctly, parallelism can unlock substantial performance gains.
Compiler Optimization Flags: Unveil the Compiler Magic
Compilers are not just translators; they are sophisticated tools that can optimize your code during compilation. Familiarize yourself with compiler flags tailored for performance. Experiment with optimization levels, explore inlining options, and delve into architecture-specific optimizations. Unleashing the power of compiler flags can lead to significant speed enhancements.
Profile and Benchmark: Measure, Analyze, Optimize
To truly understand and improve the performance of your C++ code, profiling and benchmarking are indispensable. Identify
Maximize C Language Efficiency with Proven Coding Tips
Maximizing C Language Efficiency with Proven Coding Tips
Programming in C can be a challenging yet rewarding endeavor. To truly master this language and unlock its full potential, developers must embrace proven coding tips that enhance efficiency and streamline their projects. In this article, we’ll explore essential strategies and techniques to elevate your C programming skills.
Essential Foundations: Mastering C Language Basics
Before diving into advanced tips, it’s crucial to reinforce the fundamentals. Ensure a solid understanding of C syntax, data types, and basic programming constructs. Building a strong foundation sets the stage for implementing more sophisticated coding techniques.
Efficiency Unleashed: Tips for Optimal Code Performance
One key aspect of C programming lies in optimizing code for peak performance. Utilize efficient algorithms, minimize resource consumption, and leverage the full power of C to create applications that run seamlessly. These tips ensure your code operates at its best, even in resource-intensive scenarios.
Invaluable Insights: Navigating Challenges with Practical Tips
Every programmer encounters challenges, and C is no exception. Gain invaluable insights into problem-solving and debugging techniques specific to C programming. Learn to navigate common pitfalls and emerge with a deeper understanding of your codebase.
Code Like a Pro: Mastering Advanced C Coding Techniques
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Uncovering Secrets: Pro Tips for C Coding Success
Unlock the secrets of C coding success with expert tips. From best practices to lesser-known tricks, these insights provide a deeper understanding of the language. Discover how to write cleaner, more maintainable code that stands the test of time.
Diving Deep: In-Depth Tips for Coding Excellence
To truly excel in C programming, go beyond the surface. Delve into in-depth tips that cover nuances, optimizations, and lesser-known features of the language. This exploration allows you to push the boundaries of what’s possible and develop a deeper connection with the intricacies of C.
Proven Proficiency: Essential C Language Mastery Tips
Achieve proven proficiency with essential mastery tips. Enhance your coding style, adhere to industry standards, and adopt a mindset of continuous improvement. These tips are the building blocks for becoming a proficient and respected C programmer.
Revolutionizing Your Approach: Game-Changing C Tips
Revolutionize your coding approach by embracing game-changing tips. From adopting new paradigms to exploring innovative libraries, stay open to transformative ideas that challenge the status quo. Revolutionizing your approach keeps your coding style dynamic and adaptable.
Empowering Your Skills: Must-Know C Coding Insights
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Boost Your C Skills Essential Tips for Efficient Coding
Boost Your C Skills: Essential Tips for Efficient Coding
Mastering the Basics: Building a Solid Foundation
Before we dive into the advanced tips and tricks, let’s start with the basics. Understanding the core elements of C, such as syntax, data types, and fundamental constructs, lays the groundwork for efficient coding. Even experienced developers benefit from revisiting these essentials, ensuring a strong foundation to build upon.
Elevating Your Code: Proven Tips for Optimal Performance
Efficiency is the name of the game in C programming. To boost your skills, focus on optimizing your code for peak performance. Implementing efficient algorithms, minimizing resource usage, and harnessing the full power of C will make your applications run seamlessly, even in resource-intensive environments.
Insider Insights: Navigating Challenges in C Programming
Every coder faces challenges, and C is no exception. Gain invaluable insights into problem-solving and debugging techniques specific to C programming. Learning to navigate common pitfalls equips you with the skills needed to overcome hurdles and build robust, error-free code.
Code Smarter: Proven Tips for Efficient C Development
Efficient coding is not just about speed but also about writing clean and maintainable code. Discover proven tips for smarter coding that enhances not only the speed of development but also the clarity of your code. Adopting best practices ensures your codebase remains manageable and scalable.
Advanced C Techniques: Coding Mastery Unleashed
Now it’s time to level up your coding prowess. Delve into advanced C techniques, exploring pointers, memory management, and complex data structures. Mastery of these concepts empowers you to write more sophisticated and efficient code, setting you apart as a skilled C programmer.
Unlocking C Secrets: Expert Tips and Tricks Revealed
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Dive Deep into C: Essential Tips for Coding Excellence
To truly excel in C programming, you need to go beyond the surface. Dive deep into essential tips that cover nuances, optimizations, and lesser-known features of the language. This exploration allows you to push the boundaries of what’s possible and develop a deeper connection with the intricacies of C.
Code Optimization: Mastering C Language Efficiency
Optimizing your code is not just about making it run faster; it’s about making it run better. Learn the art of code optimization in C by fine-tuning your algorithms, minimizing memory usage, and enhancing overall efficiency. Mastering these skills ensures your code performs at its best.
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Must-Know Tips: Navigating Challenges in C Coding
Every coder encounters challenges, but not everyone knows how to navigate them effectively. Arm yourself with
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| 0.982158 |
Linux Goodies
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A Review of the Free R Mathematics Language
Amazon Computers
R, the Free Statistics Language
R mesh plot
The plot you see above is an example of a mesh plot produced by the matrix scripting language R.
R is a language created by and used by mathematicians. R is an open source clone of the commercial language S. R is an object oriented language, and every declared function is an object. The object oriented nature makes some syntax seem peculiar, but that's because things are being done by object functions instead of language intrinsics as with other most languages.
Object oriented languages can accomplish some things that are difficult or impossible in non object oriented languages. As an example, the object nature of R provides the ability to pass a function name to a function, and have that passed function executed within the called function.
In Linux, R has a simple command line interface. The Windows version comes with a GUI interface. R has a nice history mechanism, allowing the user to scroll back through, and modify if desired, previous commands. The history is not maintained from one invocation of R to another.
R is heavily populated with statistical functions, and also contains some signal processing functions such as filtering, interpolation, and regression. R programs can be ran in batch mode, but when that is done there is no user interaction. In batch mode, input parameters must be from files, and output is to a file. The user can create a file in their home directory named .Rprofile and use it to auto-load any R modules of their own that they often used. That makes R routines quickly accessible by entering the language with just R, and then executing the functions.
R Syntax
R has the most convenient methodology for providing function calls with variable arguments. The argument list in a created function simply has the default values for optionally passed parameters defined in the function declaration statement. No logic needs to be created in the function to determine if parameters were passed or not. Most other math languages require the programmer to do some coding within a function to deal with parameters that may or not be passed. The defaulting or parsing of passed parameters in R is done completely by the R system. The following function declaration illustrates the method.
scalemat <- function(mat, sf=2){
m2 <- mat * sf
}
In the code example, the function scalemat will return a matrix scaled by a provided scale factor (sf). In the example, the sf parameter is defaulted to 2. Within the code the parameter sf can simply be used, and it will either have the defaulted valued if not passed to the function, or the passed value. Notice also that no return statement is used. The last variable created in a function is automatically the one passed back to the calling routine.
R has a list construct that can be used to package multiple non-similar arguments under one name. The elements of the list can be named when created, and the list can be returned by a function. The individual elements of the list can be accessed by index or by name, if names were assigned. The following code snippet illustrates the use of a list. Variable x is assigned a list of 3 elements. Element a is a scalar, element b is an array, and element c is a string.
x <- list(a=10, b=c(10,11,12), c="label")
u <- x$a
v <- x$b
w <- x$c
Unlike MATLAB, R does not auto-load user defined modules just because they are referenced. Modules have to be loaded with a source command or listed in the .Rprofile file. I find it works best to package related routines into module libraries so that when an R module is loaded with the source command, all relevant routines are loaded at once.
R uses some interesting syntax that takes a bit of getting used to. Even the equal sign equation nomenclature commonly used in other languages is different in R. A couple of example R equations are listed below:
x <- c(10,20,30,40)
y <- rbind(c(1,2),c(11,12),c(15,19))
As you can see, the <- operator is used, instead of the more common equal sign, to store values into variables. The first equation in the example stores an array of numbers into a variable named x. The c(...) operator is a function that creates the array. Notice the second equation. It creates a 3 row, 2 column matrix. The c(..) operator makes arrays, and the rbind operator combines arrays and matrices into rows. There is a cbind operator that combines arrays and matrices into columns.
Unlike MATLAB and Octave, R mathematical operations default to scalar operations. Special operators are used to specify matrix operations. For example, the following example illustrates multiplying a scalar cell by cell multiply of matrix A by matrix B, then the matrix multiply operator.
Scalar multiply:
C <- A * B
Matrix Multiply
C <- A %*% B
For help, the user can type help(topic) for specific documented help topics, or help.search("subject") for a list of possible help topics pertinent to the supplied subject.
R comes with many function libraries, and even more can be obtained from the Comprehensive R Archive Network known as CRAN. The CRAN website offers documentation, FAQs, and downloads or many contributed packages.
R Input/Output
R has a flexible, though different looking, collection of I/O routines. It was fairly easy, for example, to create a function that could examine ASCII files that consist of columns of numbers separated by some character, such as a tab, a comma, or a colon. The routine can determine the separator and with a single instruction read in the entire file as a matrix with the scan command, specifying the separator. It is likewise easy to read in an entire binary file as a matrix using the readBin command. Various data types can be read with the readBin command, and the user can specify if the data file to be read is little or big endian. This feature allows R to work with data that may have been created on a different computer platform.
When I was presented with the problem of analyzing some spreadsheet data, I was pleasantly surprised to find that R has a read.csv command that can read and create an intelligible list of data from comma separated files (CSV files). R can also make many spreadsheet style graphs such as bar charts and pie charts. An illustration can be seen on the Linux Survey page. If you check out the R graphs, take time to fill out the survey if you wish.
For output, R has the commonly used print command for writing to the screen, but with a twist. To output multiple values in a single print command, one must put the message together with the paste command first. Below is an example of how to print out a message containing text and values:
# How to print a composite message
print(paste("X = ",x,"Y = ",Y))
You might notice in the the previous example that the # character signifies to R that the following information is comment only.
Writing to ASCII files is done with the write command, which has many optional arguments to control output format. To write out a binary file, one uses the writeBin command, which lets the user output integers, floating point, complex, and other data types. The writeBin command also lets the user specify whether the output is to be in little or big endian.
R Graphics
The graph at the upper image is an R color contour map of the sinx/x function. R can make labeled line contours as well. The graph you see at the bottom illustrates an R color contour map with a line contour map overlay. This shows that the line contour and color contour features can be combined. Users can make such maps with many options, including lines only, colors only, and different color schemes.
R scatter plot
R has an extensive integrated graphics library for doing 2D and 3D graphics. Being statistical in nature, R also offers a number of plots that help in the statistical analysis of data. For example, given a matrix with related data in columns, a simple call to a routine called pair will produce a window full of scatter graphs that plot each column versus each other column. This allows a quick qualitative determination if any of the functions are correlated with one another.
R also provides mechanisms for obtaining mouse position and button information from graphics windows. R can present image graphics as well, and do so with respectable speed. While R doesn't come with image I/O routines, the Comprehensive R Archive Network has download-able R routines for loading and saving fits file formats. Fits is a commonly used color capable graphic format used in astronomy.
As it happens, there are many utilities in Linux that can handle fits files, along with about every other graphics format you might have heard of. The utility convert from the imagemagick package is one that can convert just about any kind of graphics format to any other graphics format. In the process, it can also enhance, crop, or provide many other operations on the image during conversion. So having even just the fits file format available for R is sufficient in Linux, given the capabilities of the convert utility to convert anything else to fits format.
I converted a little utility from PDL to R that steps through a sequence of web cam astro-photos allowing me to select a reference point for frame alignment, and if desired to crop images. The graphic display of the images is reasonably fast, and mouse control is easy to use. I created this program in several matrix languages,and found that not all did the task well. But R handles the problem nicely, giving me a handy utility for cropping, aligning, and stacking lunar and planetary images. See 6 Inch Reflector Astrophotography for examples of the images this technique can produce.
Summary
In summary, I find R to be an excellent choice for a scripting matrix language. The syntax takes a bit of getting used to, but the speed and functionality of the language is impressive. It is well documented, and supports a wide variety of graphics presentation methods. It handles a wide range of data investigation techniques, including statistics, regression, filtering, and signal processing. It has flexible enough I/O capabilities to handle different data formats, making it quite applicable for data processing tasks. It is even capable of being used for some image processing.
Below is my subjective evaluation of some characteristics of R.
Pros:
• Freely available for MacOS, Windows, and Linux.
• Very similar to the commercial language S.
• Has a very large software archive (CRAN).
• Especially good for working on statistical and time-series problems.
• R is not limited to 2 dimensional arrays.
• R has a richer variety of data types than many matrix languages, such as character, logical, integer, complex, and double.
• R supports more data forms than just multi-dimensional matrices, such as arrays and lists.
• R has a good enough collection of file i/o routines to allow a user to move files to and from most any external utility.
• R can import comma separated variable (CSV) files from spreadsheets.
• R has the easiest method of creating variable number of argument functions that I've ever seen.
• R has 2D and 3D graphics support, and mouse clicks on graphs can return information to the R script.
• R can make bar charts and pie charts in addition to common math language graphs
• R has support to help in the generation of reports based upon analysis results.
• R works well interactively and can be ran in batch mode.
• Cons:
• The use of the <- symbol instead of the more common = for data assignment can take a bit of getting used to.
• While R is very fast at performing matrix operations, it slows down considerably when loops are used extensively.
• For interactive use, R is a bit slow on high density graphs, like photographic images.
• R doesn't directly read any graphic file formats, though Fits file packages are available from the CRAN archive. I found that adding PNM graphics file routines to be very easy. R can save a graph in jpeg,png,tiff, and bmp formats.
• Because more data types are available, there's a steeper learning curve than with say, Octave.
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Introduction to R
Basic Computation
Welcome!
Welcome to your first tutorial for coding in R! In this tutorial set, we'll discuss how to set up calculations, create and use basic data structures, and run several basic descriptor commands.
Keep in mind...
Throughout this tutorial, you will see code chunks like this:
2+2
Often, these code chunks will be completed and ready to go for demonstration. You should run them to see what happens.
You should also feel free to play around with them too and run them with other entries! Don't worry, you won't break the tutorial by changing the contents. :)
Some code chunks will be challenges for you to fill. In these, use the provided hints...the last hint will be the suggested solution. You can also use submit to check that your output is correct!
Arithmetic
First lets practice basic computations with R. Addition, subtraction, multiplication, division, and exponents use symbols that are likely already familiar to you.
look at the examples provided for simple computations and then produce some of your own:
56+1
66-60
45*2
81/9
5^2
sqrt(144)
Adding Parentheses
We can also use parentheses to complete multiple calculations at once.
When implmenting computations into R, keep in mind order of operations (PEMDAS), thus adding () into a certain portion of your math problem in R is essential if calculating multiple operations at once.
(25-5)/4
((6*3)-12)^2
Your Turn!
Output the code 8 plus 6, all divided by 2. The solution is available for reference:
(8 + 6)/2
#Did you use parentheses around 8+6?
(8+6)
Vectors in R
Introducing Vectors
A vector is a collection of items (for example, a list of numbers) that are tied together into one structure. To create a vector, we will use our first R function, c (which is short for "concatenate")
functions in R are usually a letter or name, followed by parentheses that include inputs for that function.
The following vector could represent the heights (in inches) of 13 adults. The entries are placed inside the function like an input, and then when I run this function, it outputs the same list of numbers, but tied together as a vector.
c(65,71,63,68,67,72,64,61,67,71,72,68,64)
Characters
An example of a character vector might be storing responses to a question that produces categorical responses. Notices that character entries should be in quotation marks (whereas numbers should typically be listed without quotation marks).
c("yes","yes","no","yes","no","yes","yes","yes","no","yes")
Sequences
In some cases (like plots), we might wish to create a sequence of equally placed numbers. There is a special function named "seq" that allows us to make a sequence from a starting value to a final value, by intervals of our choice.
Notice that this function now has multiple arguments to fill. We will define the three listed here.
seq(from = 2, to = 20, by = 2)
Leaving out the argument names
Keep in mind that in R, we don't have to fill in all of the argument names. If we list our inputs in this order, R will assume the order is...from, to, by...in that order.
seq(2, 20, 2)
Default entries
Something else to keep in mind--we don't have to fill in every possible argument to a function. Only the necessary ones. For example, if we leave the "by" argument empty, R will assume a default value of 1. Try running this to see!
seq(2, 20)
In case you're curious, you can always check out the documentation for a function by running ? in front of the name. This will give you info about what argument options are available, and what default entries are used if left undefined. It's a bit technical and confusing at first, but as you become more coding experienced, it can be very helpful to reference for new (to you) functions.
?seq
Creating Variables
We can also save vectors to a variable name--this is helpful when we might want to summarize or use this vector in a later command.
heights = c(65,71,63,68,67,72,64,61,67,71,72,68,64)
heights
breaks = seq(0,100,5)
breaks
Operations on a variable
We can complete arithmetic operations on vectors, as well as calculate various summary statistics if working with data.
Take a look at the following example, where we take our height vector and multiply it by 2.54 to convert these values from inches to centimeters.
Try changing 2.54 to a different number to observe what happens!
height = c(65,71,63,68,67,72,64,61,67,71,72,68,64)
height_cm = height*2.54
height_cm
Practice!
Give it a try! Create a sequence from 3 to 24 by 3's. Name this as Vector, and then divide Vector by 3. It should produce a vector from 1 to 8 by 1's after this division.
______ = ___(from = __, to = __, by = __)
Vector/__
Vector = seq(from = 3, to = __, by = __)
Vector/__
Vector = seq(from = 3, to = 24, by = 3)
Vector/3
More Practice!
Now, try creating a vector with the following data representing inches of precipitation for 12 months in Champaign.
Save this data as a vector named Temp_2019
3.85, 1.90, 5.09, 4.89, 6.08, 2.82, 3.38, 2.19, 3.36, 5.00, 1.91, 1.82
FYI: Weather data for the Champaign_Urbana area can be found here: https://stateclimatologist.web.illinois.edu/data/champaign-urbana/
3.85, 1.90, 5.09, 4.89, 6.08, 2.82, 3.38, 2.19, 3.36, 5.00, 1.91, 1.82
Temp_2019 = c(...)
Temp_2019 = c(3.85, 1.90, 5.09, 4.89, 6.08, 2.82, 3.38, 2.19, 3.36, 5.00, 1.91, 1.82)
Temp_2019
Data Frames (and Tibbles) in R
Introducing Data Frames
A data frame in R is a collection of vectors, where each vector represents one variable of data. Typically, each column of a data frame is a variable, and each row represents one observation (set of measurements from one individual at one point in time).
In an upcoming software video, we'll see how to use RStudio to import data into a session (since most of the time, we're working with data in a spreadsheet or some other file), but for now, we'll focus on data we create directly in R, or some named datasets that exist online in the R universe already for learning purposes.
Upload the Prostate Data frame with Package
In the following code, we will upload a data frame named "prostate." This data is saved in a package named "faraway." Packages are ways that R users can create code structures or data frames and share them with others! We'll use packages many times throughout the course.
Note that if using a package on your personal computer, you'll need to install it before librarying it. So if you want to replicate this next bit on your own computer, be sure to run the following: install.packages("faraway")
Once installed, you can activate any package for use in your current session of R by running library(package_name). In this case, the package name is faraway, so we will run that here!
library(faraway)
prostate
Note that library(faraway) calls on the location of this data, and then prostate is one (of many!) data frames in this package that we can access. By running just the name, we get a snapshot of this data frame in our output.
A Little Exploration
We can use different functions on a data frame to learn more about it. Here are a couple basic ones.
"Number of rows (observations)"
nrow(prostate)
"Number of coloumns (variables)"
ncol(prostate)
Create a Data Frame Manually
We can also create a data frame manually by entering named vectors that we want to tie together. We will use the command "data.frame", which concatenates vectors that we list separated by commas.
Class = data.frame(
heights = c(65,71,63,68,67,72,64,61,67,71,72,68,64),
responses = c("yes","yes","no","yes","no","yes","yes","yes","no","yes","no","no","yes")
)
Class
New Lines to Improve Readability
Notice in the code chunk above, we hit "enter" after each comma to list each variable in a new line. With most functions in R, you can insert line breaks to improve readability without changing the operation! We could list all of that in one long line, and it would run exactly the same, but it is now very difficult to read!
As you are learning to code, please please please make line breaks where appropriate! It will make it much easier for you and for those of us who might be helping you. :)
Data Frames with Multiple Variables
Now, can you try creating a data frame with two variables? Let's report the test scores of 5 fictional students, as well as their Names.
Scores: 90, 81, 87, 98, 78
Names: "Jose", "Maddie", "Peter", "Amy", and "Kara"
Let's call this data frame "Results."
Then be sure to call up this data frame at the end.
Don't forget to put a comma at the end of the Scores line!
______ = data.frame(
Scores = ...
Names = ...
)
Results
Results = data.frame(
Scores = c(90, 81, ...),
Names = c("Jose", ...)
)
Results
Results = data.frame(
Scores = c(90, 81, 87, 98, 78),
Names = c("Jose", "Maddie", "Peter", "Amy", "Kara")
)
Results
And Tibbles Too
You should also be aware that "tibbles" are another data structure that you may encounter. Tibbles behave exactly like data frames in basically every way--the only real difference is how they display data when called on.
In this R tutorial, you won't see a difference. In fact, this tutorial purposely displays data frames like a tibble! But if using R on your personal computer, you'll notice that data frames display clunkier. They might display as many as 1,000 rows of data, while tibbles display a truncated version, plus some additional variable info. Tibbles just give you an efficient run down!
The more data you work with in R, the more you'll notice the difference, and probably realize why tibbles are easier to work with than data frames.
We can actually take the same data from earlier and save it as a tibble.
Class = tibble(
heights = c(65,71,63,68,67,72,64,61,67,71,72,68,64),
responses = c("yes","yes","no","yes","no","yes","yes","yes","no","yes","no","no","yes")
)
Class
Summarizing Data
Summarizing Data
When analyzing data, we are often interested in summarizing certain variables in our data.
The summary command is a quick way to produce several helpful summary statistics for all of our variables at once. Summary produces the 5-number summary and the mean for all variables.
library(faraway)
summary(prostate)
We can also produce specific summaries for specific variables using commands like mean, sd, and median. Just make sure you call on specific variables by using the $ operator. This allows you to access a specific element of the data frame.
sd(prostate$lweight)
mean(prostate$lweight)
median(prostate$age)
Exploring the diabetes data frame
Now Lets take a look at a new dataset
library the faraway package again, and then call up the data frame named diabetes to display.
library(_______)
________
library(faraway)
diabetes
Calculate the numbers of observations from the dataset:
nrow(___)
nrow(diabetes)
Summary
Now, run a summary of the diabetes data frame.
summary(____)
summary(diabetes)
More Statistics
And lastly, calculate the standard deviation of the age variable (within diabetes).
sd(diabetes$____)
sd(diabetes$age)
This tutorial was created by Brandon Pazmino (UIUC '21) with editing and maintenance by Kelly Findley. We hope this experience was helpful for you!
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java.sql.PreparedStatement
Sanitizing user input is a means to secure an application. The JDBC™ standard however provides a mechanism being superior regarding the purpose of protecting applications against SQL injection attacks. We shed some light on our current mechanism sending SQL statements to a database server:
Figure 884. SQL statements in Java applications get parsed at the database server Slide presentation
SQL statements in Java™ applications get parsed at the database server
Figure 885. Two questions Slide presentation
1. What happens when executing thousands of SQL statements having identical structure?
2. Is this architecture adequate with respect to security concerns?
Figure 886. Addressing performance Slide presentation
INSERT INTO Person VALUES ('Jim', '[email protected]')
INSERT INTO Person VALUES ('Eve', '[email protected]')
INSERT INTO Person VALUES ('Pete', '[email protected]')
...
Wasting time parsing SQL over and over again!
Figure 887. Addressing performance mitigation Slide presentation
INSERT INTO Person VALUES
('Jim', '[email protected]'),
('Eve', '[email protected]'),
('Pete', '[email protected]') ... ;
Dealing with large record counts even this option may become questionable.
Figure 888. Restating the SQL injection problem Slide presentation
The database server's interpreter may interpret an attacker's malicious code among with intended SQL.
• User input is being interpreted by the database server's interpreter.
• User input filtering my be incomplete / tedious.
Figure 889. Solution: Use java.sql.PreparedStatement Slide presentation
• User input being excluded from parsing.
• Allows for reuse per record.
Figure 890. PreparedStatement principle. Slide presentation
PreparedStatement principle.
Prepared statements are an example for parameterized SQL statements which do exist in various programming languages. When using java.sql.PreparedStatement instances we actually have three distinct phases:
Figure 891. Three phases using parameterized queries Slide presentation
1. PreparedStatement instance creation: Parsing SQL statement possibly containing place holders.
2. Set values of all placeholder values: SQL values are not being parsed.
3. Execute the statement.
Steps 2. and 3. may be repeated without re-parsing the underlying SQL statement thereby saving database server resources.
Our introductory toy application Figure 854, “JDBC™ backed data insert ” may be rewritten using PreparedStatement objects:
Figure 892. PreparedStatement example Slide presentation
final Connection conn = DriverManager.getConnection (...
final PreparedStatement pStmt = conn.prepareStatement(
"INSERT INTO Person VALUES(?, ?)");❶
pStmt.setString(1, "Jim");❷
pStmt.setString(2, "[email protected]");❸
final int updateCount = pStmt.executeUpdate();❹
System.out.println("Successfully inserted " + updateCount + " dataset(s)");
An instance of java.sql.PreparedStatement is being created. Notice the two question marks representing two place holders for string values to be inserted in the next step.
Fill in the two placeholder values being defined at ❶.
Caution
Since half the world of programming folks will index a list of n elements starting from 0 to n-1, JDBC™ apparently counts from 1 to n. Working with JDBC™ would have been too easy otherwise!
Execute the beast! Notice the empty parameter list. No SQL is required since we already prepared it in ❶.
Figure 893. Injection attempt example Slide presentation
Jim', '[email protected]');DROP TABLE Person;INSERT INTO Person VALUES('Joe
Attacker's injection text simply becomes part of the database server's content.
Problem solved!
Figure 894. Limitation: No dynamic table support! Slide presentation
• SELECT birthday from Persons
• PreparedSatatement statement =
connection.prepareStatement("SELECT ? from ?" );
statement.setString(1, "birthday") ;
statement.setString(2, "Persons") ;
ResultSet rs = statement.executeQuery() ;
In a nutshell: Only attribute value literals may be parameterized.
Providing an attributes name as parameter.
Providing the table name to be queried as parameter.
Setting the desired attributes name intending:
SELECT birthday FROM ...
Setting the table name to be queried intending:
SELECT birthday FROM Persons
Fails: Only attribute value literals are allowed.
exercise No. 10
Prepared Statements to keep the barbarians at the gate
Q:
Use PreparedStatement objects to sanitize your flawed Interactive inserts, connection properties, error handling and unit tests implementation being susceptible to SQL injection attacks.
When you are done repeat your injection attempt from Attack from the dark side . You may require larger string lengths in your SQL schema for accommodating the injection string.
A:
See:
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Manduca Sexta Lab Report
967 Words 4 Pages
Metabolism is a complex process in organisms that convert the food into energy for organism to function properly. Metabolic rate is typically defined as the amount of energy the organism is currently using to maintain the activity (Perkin, 2015). Since metabolism is a key in sustaining the organisms’ life, we decided to investigate the experiment about metabolic rate caterpillar, Manduca sexta. There are many techniques used to measuring the metabolic rate, but there are only best method that can be done in laboratory: “quantification of heat production and quantification of gas consumption” (Perkin, 2015).Our investigation is about measuring the oxygen consumption of the caterpillar in the trial duration when it was placed in sealed chamber along with chemical absorbing CO2 produced. Metabolism are mostly varies in …show more content…
Since we need to find that whether there is a statistically correlation between the body mass and metabolic rate of Manduca sexta, Regression test was used to analyze our data. The independent variable is the metabolic rate and the dependent variable is body mass.
3. Result The body mass of caterpillar (Manduca sexta) varied from 0.25g to 1.55g. The measured temperature inside of the chamber varied in different caterpillar and ranged from 22.0°C to 23.1°C. The volume of O2 consumption in 15 min ranged from 0.0mL to 0.60mL. The metabolic rate value (mL/min) was 0 to 0.04. From the Regression test, the P value is 0.079, coefficient value is 0.019 and 95% confidence interval value is from -0.0033 to 0.0405. It can be seen the correlation between body mass of Manduca sexta and its metabolic rate based on the graph (Fig.1) Figure 1: The correlation between body mass of Manduca sexta and its metabolic rate 4.
Related Documents
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JStellato JStellato - 7 months ago 35
C# Question
Linq Group By with Count and Key Name
I'm attempting to get the company name from a table in which I create the new anonymous type after a group. The query works if I comment out the "CompanyName" Line
db.tbl
.GroupBy(a => a.ID)
.Select(b => new {
// This line is where I need help, I want to grab the company name
CompanyName = b.GroupBy(x=>x.CustomerName).ToString(),
CustomerId = (int) b.Key,
TotalQuotes = b.Count()
})
Answer
You don't need to Group each list again.
As I suppose the CustomerName will be the same for all the entities part of a Group, you can simply take the first entity and extract from it the CustomerName:
db.tbl
.GroupBy(a => a.ID)
.Select(c => new {
CompanyName = c.First().CustomerName,
CustomerId = (int) c.Key,
TotalQuotes = c.Count()
});
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| 0.939273 |
Important questions on Traffic Flow in Transport domain
1. What’s CE?
CE is customer edge, it’s the network device located at customer site.
It should have at least 1 connection towards provider edge device.
2. What’s PE?
PE is provider edge, it’s the interfaces between clients and service provider network.
It should have at least 1 interface outside the provider network.
3. What’s P?
P is provider core device, it’s the router or network device that has all interfaces inside the service provider network.
4. What’s UNI?
UNI is user to network interface.
It’s the demarcation points between subscriber and service provider, it can be the connection between CE and PE.
5. What’s NNI
NNI is network to network interface.
It’s the connection between 2 service providers.
It’s should be between 2 PE devices.
6. What’s the ELINE
It’s the point to point Ethernet service.
7. What’s ELAN?
It’s the multipoint to multipoint Ethernet service.
1. What’s E- Tree?
It’s Ethernet point to multi point services where the root node can communicate with all leafs, but leafs can’t communicate with each other.
2. What’s the Pesudo wire?
It’s a virtual connecycan be created to transport any kind of legacy technology traffic like TDM in to packet networks.
3. What’s the trail?
It’s a logical transmission line created virtually be software configuration to transport the traffic inside optical system.
Trail can be ODU, OTU, OMS, OTS, client.
LinkedIn: :point_down:
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germantown wi population speck clear case iphone xr
are identical twins completely identical
Whereas for identical twins since one egg is splitting into two, the two cells have the same exact DNA make up and chromosomes. While we Do identical twins have identical characteristics? btk5093 September 17, 2015 at 4:47 pm. Monozygotic twins, or identical twins, are formed by a single zygote that splits itself into two blastocysts. Some of the differences can be caused by the environment. In the Hensels case, the egg separation process started but it did not finish, leaving a partially divided egg. Twins have long been the darlings of genetic research. That actually can happen two twins born, 1 on New Years Eve 11:59pm and another New Years Day 12:00am. These fraternal twins are no more alike than any other siblings in Although identical twins share the same genetic makeup, one womb, physical characteristics, and many more, they are not necessarily indistinguishable. The twins were born in South Korea in 1985 and adopted by different Jewish American families. In other words, the photons formed twins even though they were born completely independently of one another. Identical twins share the same genes. After: 182 pounds. The team analysed 3,046 DNA samples from identical twins in the UK, Australia, the Netherlands and Finland, and compared this to a control group of 3,396 non-identical twins. The mixed race twins with DIFFERENT colour skin and eyes: Amelia and Jasmine become UK's first sisters to be genetically identical but don't look the same. The researchers identified a link this is completely normal. Di di twins can be identical or non-identical, but are actually more likely to be non-identical, because of the way this type of twin occurs in your womb. Identical twins start out as a singleton pregnancy, and are also known as monozygotic twins. Your response should be able to distinguish Identical twins have the same genes or DNA. They are nurtured in equal prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is gay, the co-twin should also be gay. Because they have identical DNA, it ought to be 100%, Dr. Whitehead notes. But the studies reveal something else. Before: 5.9 mmol/liter. Identical twins are genetically the same, but the laws of genetics dont completely determine your physical appearance. Conjoined Twins. Pt 1: 1.What exactly are twins, and how do they arise? But this does not mean the twins will be identical in every way. How does this So even if identical twins are genetically similar, the pressure faced by the fetus in the womb can affect their fingerprints. 75% of conjoined twins are female.. As a slight curve ball, there have also been a handful of cases of semi-identical twins, which are thought to occur due to simultaneous fertilization of the egg It occurs very rarely when two sperm fertilizes a single egg which then splits. These twins share the same genetic material. Not All Twins Are Identical (Even Identical Ones) - Medium Twins are two offspring produced by the same pregnancy. genetics reproduction mitosis twins.
NOTE: This section is reserved for twins who do not look alike at all; brother-sister twins who look alike go to Half-Identical Twins.. Anime. Even the difference in the length of umbilical cord can make changes to the fingerprints. While twins may confuse us humans, canines can sniff out their differences. This story is just completely insane I mean both were adopted as babies and both were named James. Non-identical twins are uniquely separate individuals who just happen to be gestating at the same time and place as each other. Identical twins Genetic materials called chromosomes in both babies are completely identical. Nevertheless, these isogenic individuals are not completely identical, but show phenotypic discordance for many traits from birth weight to a range of complex diseases . They start with identical genes, because each is formed from a single fertilised egg that splits into two embryos. Non-identical twins are created when a woman produces two eggs at the same time and both are fertilised, each by a Mentor Program Coordinator. Non-identical twins are also known as fraternal twins or dizygotic twins Fraternal twins can be different genders because they are two completely different eggs getting fertilized; but even two same gender fraternal twins do not look completely alike. Associate Editor. If we assume that identical twins are exactly identical, then if we make a clone of a twin will all three be exactly identical? On average, identical twins are more similar in personality traits and (especially) IQ than non-identical twins or other siblings. This is one of the main pieces of evidence for their being some genetic influence on IQ and personality. However, identical twins can be quite dissimilar in these characteristics. Identical twins look alike and share the same DNA, but they aren't completely identical. The most common type of twins are non-identical twins, which can be the same or different sexes. Because the egg was fertilized by one sperm, identical twins have an almost identical genetic code, and their gender is always the same. The fact that they were separated at birth and still They moved to Los Angeles, California when they were 16 years old. Korean identical twins met for the first time in Florida on their 36th birthday after being separated at birth. Nov. 22, 2021 Identical twins share the same DNA, but one twin can suffer from type 2 diabetes while the other twin does not develop the disease. Share. Because monozygotic twins were thought to be genetically identical, they were perfect for sorting out which traits Learn vocabulary, terms, and more with flashcards, games, and other study tools. ; In Corsair, fraternal twins Aura and Leti are clearly related yet distinct, with Leti taking much more after their father's side and Aura taking more after their mother's side. 12 MAY 2020. Identical twins or monozygotic twins are developed from a single zygote that splits into two embryos. Even mammals form natural clones: identical twins are a common example in many species. Factors that increase your chances of having twins include: 4. Start studying identical twins. While most identical twins do share almost completely identical DNA, some do not. Non-identical twins form from two separate eggs which are fertilized by two completely separate sperm. This can change the physical appearance of the twins and cause a size discrepancy between them. This is the rarest, making up less than .1% of all pregnancies, according to Columbia University. Identical twins form from the same egg and get the same genetic material from their parents but that doesn't mean they're genetically identical by the time they're born. It's common especially in drawn or animated media, where the creator has complete control over the appearance of the characters to use brother-sister twins as being each other's Distaff Counterpart and Spear Counterpart. When identical twins are conceived, the fertilized egg splits into two, causing two separate embryos to grow. The most common type of twins are non-identical twins, which can be the same or different sexes. Twins are defined as two offspring produced from the same pregnancy, they can be either identical or fraternal. But for the most part, basic biology says identical twins share the same DNA. Identical twins form from the same egg and get the same genetic material from their parents but that doesn't mean they're genetically identical by the time they're born. If Identical Twins Married Identical Twins, How Genetically It completely slipped my mind. The zygote divides into two or more embryos early in development. MZ twins arise from the same single cell and therefore share almost all of their genetic variants (Figure 1). Again, because the embryos develop independently after the zygotes split, identical twins
Through their production company, True Image Productions, Inc., the Merrell Twins produced and released a completely self-funded, original scripted series called "Prom Knight".
Out of 381 pairs of identical twins involved in the new study, 39 had more than 100 differences in their DNA. Identical twins are never completely identical. However, "such genomic differences between identical twins are still very rare, on the order of a few differences in 6 billion base pairs," with base pairs being the building blocks of After: 4.9 mmol/liter. The Identical Twin ID Tag trope as used in popular culture. Identical twins will share the same genetic information so the same genetic markers can be identified. 2. Thus identical twins, though they start with the same genes, likely develop different personalities in the same environment partially based on how they interact with their This causes the babies to be born conjoined. These separate zygotes go on to form embryos. In a 2011 study published in the journal PLOS One, German shepherd police dogs were presented with the scents of identical twins.Then, they were then able to find the exact matches among jars that contained scents from other people that were meant to distract them. Identical twins have identical DNA fingerprints because their DNA codes are basically cloned copies of each other. Identical, or monozygotic, twins come from the same fertilized egg. There are always small physical differences that you can use to tell one twin from another. Trusted Source. That means a different genetic code and the possibility that fraternal twins will not look that much alike.
Answer (1 of 2): Any two siblings of the same family may resemble each other but they cannot be completely identical.Maternal and paternal genes undergo shuffling during the process of Identical, or monozygotic, twins occur when a single egg, fertilised by a single sperm, divides and makes two babies. Humans have always been fascinated by identical twins. Your twins being in separate sacs means that your pregnancy is Fraternal twins occur when two egg cells are each fertilized by a different sperm cell in the same menstrual cycle. So, at some point during cell division (before 14 days post-conception), identical twin embryos share It is interesting to note that although Ross gained greater muscle mass with a traditional diet, Hugo reported no symptoms of weakness and had a feeling of similar strength while eating a vegan diet. These can be used to tell twins apart. 7 thoughts on Are identical twins really identical? It has been reported that most parents of identical twins actually believe their children are fraternal twins because they are not identical in every way. Do identical twins always look alike? If we break this word down, mono means one, and zygote means So ya, identical twins could fool everybody with their looks, but they aint fooling the fingerprint test! Thus, the twins share the same DNA from their mother but each gets a slightly different version of their father's DNA. Answer (1 of 10): Identical twins have exactly the same genetic sequence (well, there could be a small number of somatic mutations that distinguish them, but in general we can assume that Dizygotic twins, or fraternal twins, are formed by two different zygotes fertilized by two sperm. Why do identical twins come out at the same time? Why cant the twins be born years apart and still look completely identical?!? Identical twins predominantly have the same sex. But, there have been extremely rare instances where the monozygotic twins are of different sexes. This scenario is so rare that there have been only a few reported cases so far and it is unlikely that you will come across such twins in your lifetime. Parents of identical twins Even though identical twins are from the same sperm and egg and therefore have exactly the same set of chromosomes and therefore genes, Another big factor why identical twins aren't necessarily completely identical is the environment which each of them were raised in. When two different eggs are fertilized by two different sperm, the twins resulting from this are fraternal. Just how their individuality emerges has remained a bit of a mystery. Since identical twins develop from one zygote, When a mother gives birth to twins, the offspring are not always identical or even the same gender. Mostly, newborn twins are identical but once they get out into the world and start forming an identity of their own, the physical and mental changes that they undergo are clearly visible. To narrow it down, there are two major factors that are responsible for identical twins not looking identical; Environmental differences and DNA differences . ENVIRONMENTAL DIFFERENCES There are various environmental influences that can affect the genes of identical twins. 20 surprising facts about identical twins. Conclusion. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. They should be The differences between identical and fraternal twins are due to how they are conceived. Being identical twins is awesome! This is only possible with identical twins. When their fascinating case came to light, scientists saw how very valuable they could be to the study of reunited twins. (Zappys Technology Solutions) The original fertilized egg
It is possible to have triplets where two of the babies are identical twins (and may share one placenta, and even one sac) and the third baby is non-identical (with completely separate placenta and sac). Epigenetic patterns can separate twins over time. Although they share similar DNA, it is not completely the same. The DNA replication If we have a child that is from You have an identical best friend and worst enemy. Molly Sinert and Emily Bushnell embraced each other for the first time at Hyatt Centric Las Olas Fort Lauderdale on March 29, according to Good Morning America. Improve this question. Research published on Non-identical twins form from two completely separate eggs which are fertilised by two completely separate sperm. Di Di identical twins: the early years. Shutterstock. When identical twins are conceived, the fertilized egg splits into two, causing two Of 381 pairs of identical twins studied and two sets of identical triplets, scientists found that 15% of them had a substantial number of mutations specific to one twin but not the other, the researchers write. But a new study says This is because both babies come from the same egg and sperm. Fraternal Twins. A new type of twinning was identified in 2007. More types of twins exist than previously thought. Monochorionic-Monoamniotic (Mono-Mono): Both twins share the same amniotic sac and the same placenta. The Jim twins are so interesting. Even though identical twins come from the same fertilized egg, in the end each twin has slightly different DNA. BONUS FACT: Identical twins are always the same gender, and only fraternal twins can be different genders. This is why identical twins can have differing fingerprints. Twin pregnancies have unique risks and outlooks. Answer (1 of 10): Identical twins have exactly the same genetic sequence (well, there could be a small number of somatic mutations that distinguish them, but in general we can assume that the sequences are identical). Non-identical twins are no more alike than any other brothers or sisters. Fuck, Im too high for this. Conjoined twins are formed when a woman produces one egg which doesnt fully separate after fertilization. On February 9, 1979, the Jim Twins were finally reunited. Tyler Howard Winklevoss (born August 21, 1981) is an American investor, founder of Winklevoss Capital Management and Gemini cryptocurrency exchange, and Olympic rower.Winklevoss co-founded HarvardConnection (later renamed ConnectU) along with his brother Cameron Winklevoss and a Harvard classmate of theirs, Divya Narendra.In 2004, the Winklevoss Identical twins are formed from the splitting of a zygote formed from one egg and one sperm. These are known as conjoined twins.There are two possibilities for the formation of conjoined twins- either the single fertilized egg does not split completely during the formation of identical twins, or two fertilized eggs fuse together earlier during the development. IDENTICAL Twins? Identical twins will have the same blood type and even though they are extremely similar, they may not be exactly identical due to environmental factors. Identical Twins Not So Identical Environmental influences separate twins over time 5 Jul 2005 By Cathy Tran Not so similar. Non-identical twins form from two completely separate eggs which are fertilised by two completely separate sperm. But from that moment onwards, their DNA begins diverging. Veronica and Vanessa are identical twins born on August 6, 1996 in Kansas City, Missouri. As it turns out, The change continues as the twins grow up into adults. Having identical twins is genetic. She is Mom to 17-year-old identical twins girls and a 12-year-old son. Despite the name, identical twins are rarely completely identical. So there technically have 2 birthdays and born different years. Identical twins are formed after zygote, a fertilised egg splits into two embryos and shares the same genes. The idea of having a duplicate lies at the origin of many myths and beliefs.
If a starfish is chopped in half, both pieces can regenerate, forming two complete, genetically identical individuals. Look for things like birthmarks, freckles, moles, and other distinguishing features. Female identical twins can have differences in which X chromosomes one from each parent are active. Fraternal twins or dizygotic twins, on the other hand, are developed from separate eggs that are fertilised by different sperm cells. Identical light particles (photons) are important for many technologies based on quantum physics. Beyond identical and fraternal, there's a rare third type. Kirio and Kirika from Kamichama Karin. View identical twins Megan Iversen from BZ 350 at Colorado State University, Fort Collins. These twins are always identical and can be conjoined. Also read: Determination of Sex Sometimes the identical twins are physically connected. When fraternal twins are conceived, two eggs are fertilized at the same time. A set of twins who look and act for all the world like they're identical, except for the miiiinor detail that one's male and the other's female.. How many identical triplets are there in the US? Weight: Before: 185 pounds.
The differences between identical and fraternal twins are due to how they are conceived. Recent studies have shown that identical twins have very "similar" not "identical" DNA, but for the most part, according to basic biology it is identical. These fraternal twins are no more alike than any other siblings in a family with the same biological mother and father. Identical twins, meanwhile, result when one egg is fertilized Namely, identical twins are formed when a fertilized egg separates into two embryos during the first few weeks of pregnancy. Despite having the same genetic makeup, identical twins have their own distinctive personalities. In the animal world, the eggs of female aphids grow into identical genetic copies of their motherwithout being fertilized by a male. Image by Lorilee Alanna via Pixabay. Another If two identical twins grow up to be completely different from one another, we can assume that their environments were more influential in their behaviour than genetics. Known as fraternal twins, they represent a longstanding The reason the zygote splits is thought to be inherited, which may be why some families have a few sets of identical twins. Muscle Mass: Before: 153 pounds. These twins do not share the same genetic material. 3. Their skin tone, weight, height or personality, to name a few characteristics, may be different. Identical twins come from the same egg, making their genetic makeup the same, while fraternal twins share half of their genes since they form from different eggs. One twin may have a particular medical condition, while the other does not. , German researchers examining 40 genetically identical twin mice found they could develop very distinct personalities. Because identical twins come from a single After: 152 pounds. The reason twins to not end up as identical clones of each other lies in Very rarely, the zygote splits around day 13-15, making it impossible for the twins to separate fully. These twins will be the same sex and share the same The stereotype of identical twins is that they are exactly the same: they look alike, they dress in matching outfits, they share the same likes and dislikes. The
When mom has identical twins, it means one fertilized egg splits in More research is being done to investigate this.
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CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING
Optogenetic stimulation was used on mESC-derived MEBs to implement training regimens during two important stages of neural development: neurogenesis (while still in suspension) and synaptogenesis (seeded on functionalized glass or MEAs) (Fig. 1a). Training regimens consisted of periodic stimulation with 5 ms pulses at 20 Hz in 1 s intervals for an hour (Supplementary Fig. 1a). This regimen has been shown to enhance axonal growth30, and thus would suggest that it could lead to a shift in structural potentiation in a neural network. The regimen was repeated every 24 h as differentiation occurred within the EBs, with an expectation that consistent repetition would enhance the potentiation and cause long-term changes in the firing patterns of the network. Following established differentiation protocols of mESC towards mature motor neurons31,32,33, the described training regimen was started at D2 of differentiation, at which point stem cells have been induced towards neuronal lineages, and specialization and maturation of motor neurons has been shown to take place in the subsequent 7 days (Fig. 1b). Since one of the transcription factors that drove differentiation, retinoic acid, is light sensitive, media was changed every single day immediately after stimulation to ensure that stimulation effects on MEBs were not artifacts (i.e. false positives) caused by photodegradation of factors (Supplementary Fig. 1b)34. Furthermore, since the differentiation was monitored with the expression of the motor neuronal marker Hb9 through a GFP reporter, we used the plateau of GFP expression between D8 and D9, as an indicator that D9 was an appropriate time point for seeding the MEBs on glass (Supplementary Fig. 1c). Thus, after these 7 days (D2-D9) of differentiation, stimulated (S) and non-stimulated (NS) cultures were seeded on MEA chips (Fig. 1c). Careful seeding practices were applied to ensure that ~ 20 MEBs were seeded within the sensing area of the MEAs for a ~ 50% coverage by the MEBs (Supplementary Fig. 2). Seeding in this manner ensured empty space between clusters for the extension of processes, even though some nearby clusters would start fusing into larger clusters. The resulting two groups of samples seeded on MEAs were further subdivided into two more experimental groups, referring to whether or not a training regimen was continued during network formation on chip for the consequent 15 days (D10-D25). For ease of discussion, S or NS prior to a colon (e.g. S:X or NS:X) will refer to the presence or lack thereof of stimulation, during neurogenesis, while S or NS written after a colon (e.g. X:S or X:NS), indicates the presence or absence of stimulation during synaptogenesis (Fig. 1a).
Figure 1
Approach to training mESC-derived motor neuronal embryoid body networks during neurogenesis and synaptogenesis. a Representative diagram of experimental setup combining differentiating ChR2 mESC’s and MEAs. b Representative diagram of ChR2 mESC differentiation toward motor neuronal embryoid bodies monitored by the expression of GFP guided by the motor neuronal specific Hb9 promoter (scale bar: 200 µm). c Representative image of fabricated MEA chip. d Representative spontaneous spike trains from MEA recordings of cultured embryoid body networks.
Figure 2
figure2
Intact MEBs indicate formation of internal networks and form active networks between them a (i) Scanning electron micrograph of two embryoid bodies. (scale bar: 200 µm) and (ii) confocal image showing dense clusters of synaptophysin between cultured embryoid bodies (scale bar: 50 µm). b (i) MEB cryosections showing usual internal structure. (Scale bar: 50 µm) with (ii) zoom in of internal structure of a sectioned embryoid body (scale bar: 15 µm). c Representative confocal image of MEB cryosection stained for GAD65/67 and vGlut. Triangles show GAD65/67 clusters d. Representative confocal image of entire field of view for neural culture grown on the MEA sensing area (scale bar: 200 µm) with scanning electron micrograph zoom in of embryoid bodies extending processes atop of sensing electrodes. e. Bar graph for average firing rate of 15 active electrodes for cultured embryoid body networks exposed to known neuronal signaling molecules at sequential addition of tonic baths of 10, 100 and 250 µM. Glut Glutamate, ACh Acetylcholine, cAMP cyclic AMP, cGMP cyclic GMP, NE norepinephrine, GABA gamma-aminobutyric acid) across 5 min of recording/exposure (n = 15; error bar represents SEM, * p < 0.05; ANOVA with Tukey post-hoc test).
The electrical activity of the resulting neuronal cultures was measured with the MEA system and the raw data was filtered to remove low frequencies (< 200 Hz), to remove undesired voltage artifacts (e.g. stimulation artifacts), and extract action potentials recorded as spiking events (Fig. 1d). A two-step procedure was used to remove false positives from the analyzed data: (1) the detection threshold was set at a value at which no positives would be detected from the ground electrode, then (2) the recorded spikes at each electrode were inspected to ensure that the detected spikes had the appropriate voltage phases relating to action potentials: depolarization, repolarization and refractory period.
MEB cultures form active neural networks with excitatory and inhibitory populations
In this work, neural networks were cultured from intact MEBs, in contrast to growing them as a monolayer after dissociation. The long-term goal of our study is the modulation of electrical activity of the MEBs towards downstream implantation in in-vivo or in-vitro experimental systems and modulating the functionality of such systems through the resulting interaction. When cultured in their intact form, MEBs tend to keep their spheroid shape, while extending processes which contain neurites that form networks as they undergo synaptogenesis (Fig. 2a). Furthermore, dense web-like neurite structures form within the spheroid itself (Fig. 2b) and both excitatory (vGlut) and inhibitory (GAD65/67) receptors stain positively (Fig. 2c).
Network formation was validated by exposing MEB cultures grown on MEAs (Fig. 2d) to varying concentrations of commonly used exciting and inhibiting signaling molecules for 5 min: L-glutamate, acetylcholine, cyclic AMP, cyclic GMP, norepinephrine and GABA. (Fig. 2e). As expected, L-glutamate evoked a statistically significant (repeated measures ANOVA with a Greenhouse–Geisser correction, n = 15; F(1.28,17.89) = 18.78, p = 1.88E-4) response in the network. A post hoc Tukey test showed a statistically significant positive difference at p < 0.05 between 0 µM to 10 µM, while higher concentrations, 100 µM and 250 µM, showed a decrease in firing rate with the latter showing a statistically significant negative difference to the spontaneous firing rate, most likely related to excitotoxicity35. Other excitatory signaling molecules, acetylcholine and cyclic AMP, evoked a continuously excitatory response (repeated measures ANOVA; ACh (with Greenhouse–Geisser correction), n = 15: F(2.13,29.78) = 16.14, p = 1.31E-5 and cAMP: F(3,42) = 125.49,p = 4.20E-15) continued a gradual increase in firing rate with increasing concentrations. Cyclic GMP, another cyclic nucleotide similar in function as cAMP, failed to evoke any statistically significant effect on firing rate (repeated measures ANOVA with a Greenhouse–Geisser correction, n = 15; F(2.08,29.18) = 2.86, p = 0.07). On the other hand, the inhibitory neurotransmitters evoked statistically significant effects on the MEB-derived networks, with norepinephrine (repeated measures ANOVA, n = 15; F(3,42) = 81.43, p = 1.53E-17), showing a statistically significant decrease at p < 0.05 in a post hoc Tukey test from 0 µM to 10 µM, and 100 µM to 250 µM, while GABA (repeated measures ANOVA, n = 15; F(3,42) = 191.55, p = 1.60E-24) showed a statistically significant decrease in firing rate at p < 0.05 in post hoc Tukey test at each concentration. The responses corroborated the development of endogenously active neural networks expressing different kinds of receptors. The observations that MEBs extend processes within the body itself while responding to both excitatory and inhibitory signaling molecules would lead to the hypothesis that these MEBs could be forming intrabody circuits which could be “trained” during differentiation and have these changes last after network formation.
Stimulation during neurogenesis results in morphological changes in MEB cultures
The effects of stimulation during differentiation were initially observed in neurite extension and presynaptic protein clustering. While it has been reported that neurite outgrowth could be enhanced if neural populations simultaneously underwent optogenetic stimulation30, it was not clear if effects of the stimulation on MEBs done in suspension would still result in an increase of neurite extension when later seeded on chips, as this would indicate some stable long-term changes in the neuronal system. To quantify this, S:NS and NS:NS MEBs were seeded at low confluence on gridded coverslips and imaged 6 times every two hours on D10 (1 DIV) to quantify the number of extending neurites (Fig. 3a). Observations showed a consistently statistically significant positive difference (ANOVA, n = 20; 14hrs: F(1,38) = 215.44, p = 0.0; 16hrs: F(1,38) = 148.40, p = 1.08E-2; 18hrs: F(1,38) = 257.32, p = 0.0; 20hrs: F(1,38) = 199.14,p = 1.11E-2; 22hrs: F(1,38) = 221.35, p = 0.0; 24hrs: F(1,38) = 76.11,p = 1.31E-2) of number of neurites extended for S:NS samples, compared to NS:NS, for each of the six hours the two groups were measured and compared. This indicates an increased rate of neurite extension as a result of the stimulation during neurogenesis (Fig. 3b). Next, we wanted to observe the effect of stimulation during differentiation on the propensity of the network to form synapses. To quantify this, the clustering of presynaptic synaptophysin stained with anti-SY38, was counted along individual neurites as well as per unit area between the groups NS:NS and S:S (Fig. 3c). By D11 (2 DIV) S:S samples showed a statistically significant ~ twofold increase (ANOVA, n = 10; F(1,18) = 24.58, p = 1.02E-4) of synaptophysin clusters per neurite than NS:NS samples (Fig. 3d). This increase of pre-synaptic clusters per neurite combined with the increase in neurite extension resulted in S:S samples presenting a statistically significant higher synaptophysin clusters per unit area than NS:NS counterparts at D11 (ANOVA, n = 10; F(1,18) = 40.18, p = 5.68), D13 (ANOVA, n = 10; F(1,18) = 131.58, p = 1.04E-9) and D15 (ANOVA, n = 10; F(1,18) = 74.87, p = 7.88E-8) (Fig. 3e). When monitoring the difference of pre-synaptic clusters per unit area at D13 and D15, the statistically significant difference indicated that optogenetic stimulation during neurogenesis evoked physiological responses on two important aspects of neural network development: neurite extension and presynaptic clustering (Fig. 3e).
Figure 3
figure3
Stimulation during neurogenesis affects key morphological parameters of network formation. a. Representative phase contrast images of neurite extension along the periphery of embryoid bodies between non-stimulated (NS) and stimulated during neurogenesis (S) samples (scale bar: 50 µm). b. Bar graphs representing the average number of neurites protruding from the periphery of embryoid body normalized by the perimeter of the embryoid body at a given time after seeding. Each point signifies the number of extending neurites normalized by the perimeter of an individual embryoid body (n = 20; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test). c. Representative fluorescence images of synaptic puncta stained against SY38 at D11 along a neurite. Arrow denote presynaptic puncta. (scale bar: 5 µm). d. Bar graphs representing the average number of presynaptic puncta along the length of neurites for D11. Each point corresponds to the average number of synaptic puncta along a neurite normalized the length of the neurite per field of view (n = 10; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test). e. Bar graphs representing the average number of presynaptic puncta per unit area for D11-D15. Each point corresponds to the average number of synaptic puncta per unit area in an individual field of view (n = 10; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test).
MEB network synchronicity is amplified by stimulation during neurogenesis and synaptogenesis
Network synchrony is a common parameter used to characterize a developing neural network, as it gives information on the network’s plasticity and connectivity. Various studies have successfully shown that the presence of chronic stimulation results in improved network synchrony36,37,38. In our study, we wanted to observe the long-term effects of stimulation regimens on the network synchrony and determine if these effects were amplified or shifted when the training regimen during neurogenesis was extended during synaptogenesis. From the raster plots of the spontaneous activity recorded at D21, the increased level of synchronous activity was notable between NS:S and S:S samples versus S:NS and NS:NS (Fig. 4a). This can be appreciated by the peaks above the raster plots, which correspond to a summation of the activity across all electrodes, where synchronous networks would result in discrete peaks whereas in samples that lacked coordinated firing, the resulting line plot seemed to lack any peaks.
Figure 4
figure4
MEB network synchronicity is amplified by stimulation during neurogenesis and synaptogenesis. a. Representative raster plots of MEB cultures at D25 showing network synchrony by line plots of the sum of active electrodes for each time point. b. The average correlation value (χ) was calculated for active electrodes across time for an average value for each electrode, then mapped to their respective spatial position on the MEA array. c. Bar graphs representing the mean correlation value across the culture for the MEA cultures at the different days of recording. The correlation value for the culture was calculated using active electrodes during spontaneous time of each culture for each day of recording. Each point corresponds to the correlation value across electrodes for each MEA culture. (n = 3; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test).
Similarity between electrode recordings was quantified with cross-correlation in order to quantify synchronous behavior. Values for the similarity across the network were obtained by calculating cross-correlation for all electrode combinations (Supplementary Fig. 3). For this analysis, only spontaneous recordings of active electrodes (electrodes detecting at least 10 spikes/min) were used to quantify the long-term effects of the training regimen on steady state synchrony. When average correlation values per electrodes were mapped to their position on the chip, NS:S and S:S samples showed high synchrony level ((stackrel{-}{chi }) > 0.5) across the entire network for spontaneous recordings at D21 (Fig. 4b). This showed that synchronous behavior extended across the entire network and was markedly higher for networks that were stimulated during synaptogenesis.
Interestingly, when the network wide mean synchronicity was calculated for each recording day, a trend of higher synchrony was observed for samples that had been exposed to some form of training regimen (NS:S, S:NS or S:S) but no statistical significance was observed at D11 (ANOVA, n = 3; F(3,8) = 3.42, p = 0.073) and D13 (ANOVA, n = 3; F(3,8) = 1.77, p = 0.23). At D15, a statistically significant difference (ANOVA, n = 3; F(3,8) = 7.47, p = 0.010) was observed, with a post hoc Tukey test performed at p < 0.05 showing statistical significance between NS:S and S:NS (stackrel{-}{chi }) values. Subsequently, while no statistical significance was observed for D17 (ANOVA, n = 3; F(3,8) = 3.88, p = 0.055), D19 (ANOVA, n = 3; F(3,8) = 3.58, p = 0.066) and D21 (ANOVA, n = 3; F(3,8) = 3.61, p = 0.065), a gradual trend was observed for the synchronicity of networks undergoing training during synaptogenesis (NS:S and S:S) being larger than their counterparts (NS:NS and S:NS). At D23, there was a statistically significant difference among the experimental groups (ANOVA, n = 3; F(3,8) = 8.73, p = 6.6E-3). Post hoc comparisons using Tukey test at p < 0.05 indicated that the (stackrel{-}{chi }) value for NS:S and S:S were higher than both NS:NS and S:NS groups. This statistically significance was sustained for D25 (ANOVA, n = 3; F(3,8) = 6.46, p = 0.016), with the post hoc Tukey test showing significant difference between (stackrel{-}{chi }) for S:S and (stackrel{-}{chi }) for NS:NS as well as S:NS. (Fig. 4c).
Spectral density elucidates changes in steady state firing
Conventionally, electrophysiological behavior is characterized by firing rate during set epochs and burst parameters (Supplementary Fig. 4). However, when analyzing these parameters during spontaneous firing, there was no discernable trend in the change of long-term firing rate or burst parameters between experimental groups. However, when observing the spike data during steady state of a more mature neural network (D25), there were deviations on how the spike firing clustered into bursts, despite the fact that no clear change in the number of spikes was observed (Fig. 5a). We accredited this seeming conflict between the quantitative and qualitative data to the selection method of the burst detection parameters (See Quantification and statistical analysis). In order to avoid arbitrariness in the selection of these parameters, we decided to characterize the data in the frequency domain. For this reason, we focused on characterizing spontaneous firing recorded on MEAs by comparing changes in the power spectrums of recorded signals calculated through Fourier transforms (Fig. 5b). To obtain spectral profiles, binned spike counts were divided into 10-s-long contiguous windows and transformed to the frequency domain, thus representing the power spectrum as a function of time (Fig. 5b). When initially calculating the power spectral density (PSD) and observing between the DC frequency and the Nyquist frequency, we noticed that most of the components appeared below 7 Hz for all samples. For this reason, we compared samples between 0.1 Hz (to remove DC component) and 5 Hz. Focusing between 0.1–5 Hz, all samples except S:S, showed frequency profiles of their respective firing patterns with components across the entire bandwidth of interest. This spontaneous heterogeneous firing patterns can be expected from these cultures formed from MEBs, as they are a super-network composed of individual networks from within each MEB. On the other hand, S:S samples show a clear change in their frequency profile, where most of the spectral power fell within 0.1-1 Hz.
Figure 5
figure5
Stimulating training regimens modulates firing patterns in the frequency domain. a. Fifteen second representation of spontaneous voltage recording from NS:NS, NS:S, S:NS and S:S samples for D25. b. Smoothened (3 point moving average) and normalized (AUC) power spectra was calculated for contiguous 10 s windows across the 4 min of spontaneous recording NS:NS, NS:S, S:NS and S:S. Resulting matrices were averaged across samples. c. Bar graph for the sum of power spectral density magnitude from (b) across the spontaneous recording time between 0.1 Hz and 1 Hz (n = 3; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test).
Moreover, if the signal power is summed between the frequency range of 0.1-1 Hz, the training regimen pattern had a statistically significant effect at p < 0.05 on the power magnitude within this frequency interval (ANOVA, n = 3; F(3,8) = 20.15, p = 4.37E-4). Post hoc comparisons using Tukey test at p < 0.05 showed a statistically significant difference between power magnitude withing 0.1-1 Hz of samples non stimulated during synaptogenesis (NS:NS, S:NS) and samples stimulated throughout development (S:S) (Fig. 5c). Moreover, the post hoc Tukey test indicated a statistically significant difference between power spectra values between NS:S and S:S, implying that combined stimulation of both neurogenesis and synaptogenesis had an amplified effect on modulating the power spectra of the networks than just stimulation during synaptogenesis. This statistical significance was not observed in the mature networks (D25: ANOVA, n = 3; F(3,8) = 0.063, p = 0.98) if the power was summed for the whole frequency interval of interest (0.1-5 Hz) (Supplementary Fig. 5).
Neurogenetic stimulation changes the opto-response of MEB networks
Another aspect of consideration on the effect of training MEBs during neurogenesis was whether the early stage perturbation had some effects on how the later-stage network would respond to the same perturbation. To study this, we recorded responses to optogenetic stimulation from sets of samples that had not undergone the training regimen during neurogenesis (Fig. 6a) and compared them to those set that had undergone such regimen (Fig. 6b). Initial observation showed a difference between how the networks responded when stimulated early in the network development (D11) versus more mature networks (D25). For example, when early networks, which had a low spontaneous firing rate (D11) were stimulated, there would be a very notable evoked response during stimulation followed by a quiescent state, where the network would barely fire before returning to the baseline spontaneous firing rate. In contrast, more mature networks (D25), would still show an evoked response during stimulation but would automatically return to baseline firing rate right after stimulation ceased. What was interesting was that the quiescent time after stimulation for early S:S networks were notably shorter than those from the NS:S samples (Fig. 6a-b). Moreover, at D25, while NS:S samples would return to the same baseline firing rate right after stimulation stopped, S:S samples showed a transient change in firing rate for several seconds after the stimulation stopped (Fig. 6a-b).
Figure 6
figure6
Stimulation during neurogenesis alters response to stimulation during network formation. Summed spike counts per each 100 ms for all active electrodes across the 20 min of recording were graphed for D11 and D25 for one representative sample from NS:S (a) and S:S (b). c. Zoom-in of a for 1 min, centered around the 20 s of stimulation at D25 for sample NS:S, the arrows represent the firing rate interval prior to stimulation (FRpre), the firing rate during stimulation (FRstim) and the firing rate after stimulation (FRpost). d. Bar graphs showing the mean firing rate increase between Frstim/Frpre for D11-D25. (n = 9; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test)). e. Bar graphs showing the firing rate increase between Frpost/Frpre for D11-D25. (n = 9: error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test)). f. Raster plot of average correlation value for each electrode during 10 s bins across the entire recording time. g. Ratio of average correlation value prior to stimulation during recording and correlation value post stimulation (χpost/ χpre). (n = 3; error bar represents SEM, *p < 0.05, ANOVA with Tukey post-hoc test).
To quantify this behavior, the evoked firing rate during stimulation (FRstim) and the post-response firing rate (FRpost) were compared to the firing rate prior to stimulation (FRpre) for the three instances of stimulation within recording for each of the three MEA networks for both experimental groups (Fig. 6c). While the fold-change increase of firing rate FRpre to FRstim decreased with time for both NS:S (repeated measures ANOVA with Greenhouse–Geisser correction, n = 3; F(1.48, 11.83) = 14.79, p = 1.12E-3) and S:S (repeated measures ANOVA with Greenhouse–Geisser correction, n = 3; F(1.88, 15.02) = 11.02, p = 1.31E-3 (because more mature networks would have a higher baseline firing rate), when comparing the amount of evoked action potentials during stimulation (FRstim/FRpre), S:S samples seemed to respond more strongly to stimulation than NS:S samples (Fig. 6d). One-way ANOVA determined a statistically significant difference between NS:S and S:S FRstim/FRpre values for D13 (n = 9; F(1, 16) = 5.55, p = 0.031), D15 (n = 9; F(1,16) = 5.90, p = 0.027), D17 (n = 9; F(1,16) = 11.30, p = 4E-3), D19 (n = 9; F(1,16) = 8.78, p = 9.2E-3), D23 (n = 9; F(1,16) = 10.81, p = 4.6E-3) and D25 (n = 9; F(1,16) = 9.94, p = 6.2E-3), while only showing a trend (not statistically significant) of higher S:S FRstim/FRpre values for D11 (n = 9; F(1,16) = 4.48, p = 0.05) and D21 (n = 9; F(1,16) = 1.1, p = 0.31).
Additionally, the quiescent state response post-stimulation observed in early days (D11, D13 and D15), reflected itself in FRpost being less than FRpre, resulting in FRpost/FRpre < 1 for NS:S and S:S samples. We observed that this transient decrease in firing rate was statistically significantly shorter for the S:S samples than the NS:S for D11 (ANOVA, n = 9; F(1,16) = 19.95, p = 3.9E-4) and D13 (ANOVA, n = 9; F(1,16) = 9.49, p = 7.2E-3) (Fig. 6e). Repeated measured ANOVA indicated that FRpost/FRpre ratios increased for both NS:S (Greenhouse–Geisser corrected, n = 9; F(3.06, 24.48) = 36.92, p = 2.69E-9) and S:S (n = 9; F(7,56) = 5.66, p = 5.63E-5). Furthermore, at later days of network development, it was notable that FRpost/FRpre was ~ 1 for NS:S, meaning that the steady state firing rate was indistinguishable from that immediately following the termination of stimulation. On the other hand, S:S samples showed FRpost/FRpre values above 1 from D17 forward, indicating that the network would transiently increase in firing rate right after stimulation. One-way ANOVA showed that this increase between FRpost/FRpre values for S:S and NS:S was statistically significant for D17 (n = 9; F(1,16) = 12.19, p = 3E-3), D21 (n = 9; F(1,16) = 6.94, p = 0.018) and D23 (n = 9; F(1,16) = 9.91, p = 6.23E-3), while only showing a non-statistically significant trend for D19 (n = 9; F(1,16) = 2.16, p = 0.16) and D25 (n = 9; F(1,16) = 3.76, p = 0.071). It is relevant to mention that these effects were observed while there was no perceivable change in efficiency of the blue light to activate the ChR2 ion channels and evoke a response in the networks (Supplementary Fig. 6). These observations were corroborated by repeated measures ANOVA performed at p < 0.05, which showed no statistically significance change in efficiency (repeated measures ANOVA, n = 12; F(2,22) = 1.25, p = 0.31).
To further study how the training regimens affected network response, we also quantified the evoked response reflected in the network’s synchronicity for the initial stimulation done on the initial spontaneous interval of recording. For this purpose, raster-plots of the average values of cross-correlation (as calculated for the analysis in Fig. 4) were calculated using 10 s bins across the entire 20 min of recording (Fig. 6f). When quantifying the short term effect of stimulation during recording had on network synchronicity, by comparing (stackrel{-}{chi }) post to (stackrel{-}{chi }) pre, a trend was observed where the presence of a training regimen during neurogenesis seemed to cause the correlation fold-change ((stackrel{-}{chi }) post/(stackrel{-}{chi }) pre) for S:S samples to be higher than NS:S samples. One-way ANOVA detected a statistically significant difference between (stackrel{-}{chi }) post/(stackrel{-}{chi }) pre for S:S and NS:S for days D19 (n = 3; F(1,4) = 16.49, p = 0.015) and D23 (n = 3; F(1,4) = 11.12, p = 0.029) (Fig. 6g).
Changes evoked by stimulation during neurogenesis result in genetic changes
Given the effects on neurite extension, presynaptic clustering, frequency profiles and network response to stimulation that were observed as a result of the presence of training regimens on MEBs during neurogenesis, we proceeded to determine genetic changes that could provide possible mechanistic explanations. Total messenger RNA sequencing was performed and analyzed for stimulated (S) and non-stimulated (NS) MEBs at D9, as well as EBs at D2. The differentially expressed genes in MEBs that underwent training regimens during neurogenesis were compared to those that did not, both with respect to the genetic expression of EBs sampled prior to differentiation (at D2). A total of 749 differentially expressed genes between S and NS with p < 0.05 were detected and clustered and color coded with respect to the differential expression of D2 (Fig. 7a). There were 200 genes that were upregulated during control differentiation, but this upregulation was lessened for samples that underwent training regimen (black bar), while the upregulation of 172 genes was amplified for those same samples (red bar). On the other hand, there were 202 genes whose downregulation was stagnated for samples with training regimen (yellow bar). For 173 genes, the control downregulation was further amplified after stimulation (blue bar). Something important to note was that this observed differential expression did not include changes in phenotype populations, matching the immunostaining observations (Supplementary Fig. 7). This indicated that training regimen during differentiation did not seem to noticeably disrupt the rate of phenotype specification or generation of the neural populations that generally result from the differentiation protocol (Table 1). This suggests that training regimens affected other functional pathways rather than altering the differentiation of populations. For further analysis, a more stringent threshold (p < 0.0005) was set to detect the most promising genes as key factors for the behavioral changes seen in stimulated MEB cultures. This threshold resulted in 97 differentially expressed genes for the black cluster (Fig. 7b), 63 differentially expressed genes for the red cluster (Fig. 7c), 77 differentially expressed genes for the yellow cluster (Fig. 7d) and 71 differentially expressed genes for the blue cluster (Fig. 7e). From this pool, a thorough literature study was used to identify gene targets that had been reported to be related to known neural development and function (Table 2, Supplementary Fig. 9).
Figure 7
figure7
RNA Sequencing shows differential expression as a result of optical stimulation during neurogenesis. a. Heat map of standard deviation of differential expression for genes with p < 0.05 (n = 749). Genes were primarily clustered for: (1) genes that would overexpress during differentiation and underexpressed due to stimulation, (2) genes that would overexpress during control differentiation and overexpressed further due to stimulation, (3) genes that would underexpress during control differentiation and stimulation minimized that underexpression and (4) genes that would underexpress during control differentiation and stimulation amplified that underexpression. (first color column in order: black, red, yellow, blue). Significantly differentially regulated genes, with p < 0.0005 (n = 307) were extracted as column plots for: b. black, c. red, d. yellow and e. blue clusters.
Table 1 Expression comparisons for phenotypic gene targets.
Table 2 Significantly (p < 0.0005) differentially expressed genes reported in literature as regulators of neural development.
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Advanced Reactors and Fuel Cycles
Kathryn Huff, University of Illinois at Urbana-Champaign
Usage Details
Dr. Huff is interested in modeling and simulation in the context of nuclear reactors and fuel cycles toward improved safety and sustainability of nuclear power. In the context of high performance computing, this work requires the coupling of multiple physics at multiple scales to model and simulate the design, safety, and performance of advanced nuclear reactors. In particular, thermal-hydraulic phenomena, neutron transport, and fuel performance couple tightly in nuclear reactor. Detailed spatially and temporally resolved neutron flux and temperature distributions in particular can improve designs, help characterize performance, inform reactor safety margins, and enable validation of numerical modeling techniques for those unique physics.
The current state of the art in advanced nuclear reactor simulation (e.g., the CASL DOE innovation hub) is focused on more traditional light water reactors. Dr. Huff is interested in extending that state of the art by enabling similarly high fidelity modeling and simulation of more advanced reactor designs. These designs require development of models and tools for representing unique materials, geometries, and physical phenomena. Current work includes extension of the MOOSE framework to appropriately model coupled thermal-hydraulics and neutronics of molten salt flow in a high temperature pebble-bed type reactor. Future work may include similarly challenging materials and geometries such as those in sodium cooled, gas cooled, and very high temperature reactor designs which promise advanced safety or sustainability.
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ComputerSome computer scientists create packages to manage robots. Computer, the flagship publication of the IEEE Computer Society, publishes peer-reviewed articles written for and by computer researchers and practitioners representing the full spectrum of computing and data know-how, from hardware to software and from emerging research to new applications.
Most jobs for computer and knowledge research scientists require a master’s degree in computer science or a associated discipline. Computers (ISSN 2073-431X) is a global scientific peer-reviewed open entry journal of computer science, together with computer and network architecture and computer-human interaction as its essential foci, revealed quarterly online by MDPI.
An inventory of instructions is called a program and is stored on the computer’s arduous disk Computers work by means of the program by using a central processing unit , and they use fast memory known as RAM as an area to store the instructions and information while they are doing this.
Computer scientists build algorithms into software packages that make the information easier for analysts to use. If you happen to fail to heed this caution, the program could stop working with your browser, operating system or device at any time and you could not be capable to recover your account or your tax info.
Computer packages that be taught and adapt are a part of the rising field of synthetic intelligence and machine learning Artificial intelligence based mostly products usually fall into two major classes: rule based techniques and pattern recognition programs.
Categories: Computer
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Spatiotemporal variability in fatty acid profiles of the copepod Calanus marshallae off the west coast of Vancouver Island
Date
2015-04-21
Authors
Bevan, Daniel
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Factors affecting energy transfer to higher trophic levels can determine the survival and production of commercially important species and thus the success of fisheries management regimes. Juvenile salmon experience particularly high mortality during their early marine residence, but the root causes of this mortality remain uncertain. One potential contributing factor is the food quality encountered at this critical time. The nutritionally vital essential fatty acids (EFA) docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) are essential to all marine heterotrophs, and their availability has the potential to affect energy transfer through a limitation-driven food quality effect. Assessing variability in DHA and EPA in an ecologically important prey species of juvenile salmon could give insight into the prevalence and severity of food quality effects. On the west coast of Vancouver Island (WCVI), one such species is the calanoid copepod Calanus marshallae. This omnivorous species possesses a high grazing capacity and the ability to store large amounts of lipids. As it is also an important prey item for a diverse array of predators, including juvenile Pacific salmon, C. marshallae plays a key role in energy transfer from phytoplankton to high-trophic iv consumers. This study quantified spatiotemporal variability in the quality of C. marshallae as prey for higher trophic levels using three polyunsaturated fatty acid indicators: DHA:EPA, %EFA and PUFA:SFA (polyunsaturated fatty acids to saturated fatty acids). Samples were collected on the WCVI in May and September of 2010 and May 2011. The environmental parameters included in the analysis were the phase of the Pacific Decadal Oscillation (PDO), sea surface temperature (SST), latitude, station depth, and season (spring versus late summer). Despite a phase shift in the PDO from positive to negative, overall means of the fatty acid indicators did not vary between May 2010 and May 2011. Same-station %EFA values rarely fluctuated more than 5%. DHA:EPA ratios were more variable but without a discernable pattern, while PUFA:SFA ratios decreased in shelf stations and increased offshore. Contrary to expectations, fatty acid indicators showed a weak positive correlation or no relationship with SST, nor was there a relationship with latitude. The narrow temperature range observed across all stations suggests that temperature may not play a significant role in PUFA availability off the WCVI. There were, however, significant relationships between the fatty acid indicators and bottom depth and season. Shelf and slope stations showed significantly higher %EFA and PUFA:SFA than did offshore stations (depth >800 m), with this gradient appearing stronger in May than September. While the food quality represented by C. marshallae was consistent across all shelf stations, the lower food quality observed offshore could potentially affect juvenile salmon growth along the WCVI where the shelf narrows to less than 5 km.
Description
Keywords
Polyunsaturated fatty acids, DHA, EPA, Copepod, Juvenile salmon, Food quality, Calanus marshallae
Citation
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File Include 01
This exercise is one of our challenges on File Include vulnerabilities
PRO
Tier
Medium
< 1 Hr.
10228
Many web applications need to include files for loading classes or sharing templates across multiple pages. "File Include" vulnerabilities occur when user-controlled parameters are used in file inclusion functions like `require`, `require_once`, `include`, or `include_once` without proper filtering. This can allow an attacker to manipulate the function to load and execute arbitrary files.
In this lab, you will explore both Local File Include (LFI) and Remote File Include (RFI) vulnerabilities. By injecting special characters or using directory traversal techniques, you can read and execute files, potentially gaining control over the server. The lab also demonstrates how PHP's configuration option `allow_url_include` can enable remote file inclusion, leading to severe security risks.
Want to learn more? Get started with PentesterLab Pro! GOPRO
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<![CDATA[Inside Skylight]]>https://blog.skylight.io/https://blog.skylight.io/favicon.pngInside Skylighthttps://blog.skylight.io/Ghost 4.48Wed, 05 Oct 2022 14:23:48 GMT60<![CDATA[Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript [2022 Update]]]>https://blog.skylight.io/ts-extends-confidence-2-2022/6255c501e6cdc9003df9dff4Thu, 14 Apr 2022 17:32:39 GMT
This article is part 2 of a series on converting your Ember app to TypeScript to foster confidence in your engineering team, based on my talk for EmberConf 2021 (and updated in 2022 based on the latest and greatest Ember + TypeScript practices). You can watch the full talk below, but note that this blog post will differ substantially since it has been updated. (You can see the old version here if you want to see how much has changed in the last year!)
We started with some basics: "What even is a type? What is TypeScript?" Now, we'll look at what TypeScript looks like in an Ember app before circling back to the benefits of TypeScript in the context of developer confidence.
Table of Contents
A Metatutorial
Let's convert an app to TypeScript! We'll use the Super Rentals app from the Ember Guides tutorial as our example. Super Rentals is a website for browsing interesting places to stay during your post-quarantine vacation.
Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript [2022 Update]
Super Rentals is a very modern Ember app, using the latest and greatest Ember Octane features. Admittedly, using TypeScript with pre-Octane Ember was clunky. With Octane and native classes, however, using TypeScript with Ember is pretty straightforward.
If you are not familiar with Ember Octane idioms, I recommend following the Super Rentals tutorial before following this one. Otherwise, you can start with:
$ git clone https://github.com/ember-learn/super-rentals.git && cd super-rentals
Setup
Installing TypeScript
The first step is to run ember install ember-cli-typescript. Installing the ember-cli-typescript package adds everything you need to compile TypeScript with Ember.
$ ember install ember-cli-typescript
🚧 Installing packages…
ember-cli-typescript,
typescript,
@types/ember,
@types/ember-data,
Etc…
create tsconfig.json
create app/config/environment.d.ts
create types/super-rentals/index.d.ts
create types/ember-data/types/registries/model.d.ts
create types/global.d.ts
This includes:
• The typescript package itself.
• A default tsconfig.json file.
• Some basic utility types and directories.
• And types packages for each of Ember's modules.
While Ember itself doesn't have types baked in (but they are coming soon!), there is a project called Definitely Typed that acts as a repository for types for hundreds of projects—including Ember. You install these types as packages, then import them the same way you would a JavaScript module.
LET'S COMMIT!
Installing Glint
In addition to TypeScript, we also need to install Glint. Glint is a template-aware tool for performing end-to-end TypeScript type-checking on your Ember project. With Glint, your templates will be checked against your TypeScript files and vice versa! 😍
To set up Glint, you first need to install it. (You'll also need to add the ember-modifier package if your project doesn't already have it, as Glint assumes you have it installed.)
$ yarn add --dev @glint/core @glint/environment-ember-loose ember-modifier
Then, add a Glint configuration file. The environment key is set to ember-loose, the environment recommended by the Glint team for Ember projects. We are also adding the optional include key so that we can gradually enable type-checking for our app. For now, include only '' so that Glint isn't checking anything yet.
# .glintrc.yml
environment: ember-loose
# FIXME: Remove include key before merge
include:
- ''
Next, we need to import the types for the ember-loose environment. We'll also add a catch-all "template registry" for now so that we won't be bombarded with errors once we start type-checking our files. We'll talk about the template registry later, so try not to dwell on it now.
// types/super-rentals/index.d.ts
import '@glint/environment-ember-loose';
// NOTE: This import won't be necessary after Glint 0.8
import '@glint/environment-ember-loose/native-integration';
// FIXME: Remove this catch-all before merge
declare module '@glint/environment-ember-loose/registry' {
export default interface Registry {
[key: string]: any;
}
}
// ...
Finally, to see helpful red squiggly lines in VSCode, install the typed-ember.glint-vscode extension. You may need to reload your VSCode window after installing to see errors. (NOTE: The Glint team recommends also disabling the vscode.typescript-language-features extension, but there are multiple bugs if you follow that advice.)
LET'S COMMIT!
Strict Mode
As I mentioned in Part 1, you can configure TypeScript's strictness. There are two ends of the spectrum here:
Start with all the checks disabled, then enable them gradually as you start to feel more comfortable with your TypeScript conversion. I do recommend switching to strict mode as soon as possible because strictness is sorta the point of TypeScript to avoid shipping detectable bugs in your code.
// tsconfig.json
{
"compilerOptions": {
"alwaysStrict": true,
"noImplicitAny": true,
"noImplicitThis": true,
"strictBindCallApply": true,
"strictFunctionTypes": true,
"strictNullChecks": true,
"strictPropertyInitialization": true,
"exactOptionalPropertyTypes": true,
"noPropertyAccessFromIndexSignature": true,
"noUncheckedIndexedAccess": true,
"noFallthroughCasesInSwitch": true,
"noUnusedLocals": true,
"noUnusedParameters": true,
"noImplicitReturns": true,
// ...
}
}
Alternatively, you can start in strict mode. This is the strategy we will use for converting Super Rentals, since I want you to see the full power of TypeScript.
// tsconfig.json
{
"compilerOptions": {
"strict": true,
// ...
}
}
In fact, I want my TypeScript even stricter. In addition to strict mode, let's enable as many strict checks as we can. Why not!?
// tsconfig.json
{
"compilerOptions": {
"strict": true,
"exactOptionalPropertyTypes": true,
"noPropertyAccessFromIndexSignature": true,
"noUncheckedIndexedAccess": true,
"noFallthroughCasesInSwitch": true,
"noUnusedLocals": true,
"noUnusedParameters": true,
"noImplicitReturns": true,
// ...
}
}
I'm going to also add the typescript-eslint plugin, which adds even more checks:
yarn add -D @typescript-eslint/parser @typescript-eslint/eslint-plugin
(👋👋 NOTE: If you're following along, you'll also need to add some boilerplate, and you remove babel-eslint/@babel/eslint-parser.)
And finally, let's change the noEmitOnError config from the ember-cli-typescript default of true to false. We'll talk about why in the next section.
// tsconfig.json
{
"compilerOptions": {
"noEmitOnError": false,
// ...
}
}
LET'S COMMIT!
Iterative Migration
Gradual Typing Hacks
Alright! Now that we have installed TypeScript, we can start converting files. Fortunately, TypeScript allows for gradual typing. This means that you can use TypeScript and JavaScript files interchangeably, so you can convert your app piecemeal.
Of course, many of your files might reference types in other files that haven't been converted yet. There are several strategies you can employ to avoid a chain-reaction resulting in having to convert your entire app at once:
• TypeScript declaration files (.d.ts)—These files are a way to document TypeScript types for JavaScript files without converting them.
• The unknown type—You can sometimes get pretty far just by annotating types as unknown.
• The any type—Opt out of type checking for a value by annotating it as any.
• The @ts-expect-error / @glint-expect-error directive—A better strategy than any, however, is to mark offending parts of your code with an "expect error" directive. This comment will ignore a type-checking error and allow the TypeScript compiler to assume that the value is of the type any. If the code stops triggering the error, TypeScript will let you know.
(Experienced TypeScript users may already be familiar with @ts-ignore. The difference is that @ts-ignore won't let you know when the code stops triggering the error. At Tilde, we've disallowed @ts-ignore in favor of @ts-expect-error. If you really want to dig into it, the TypeScript team provided guidelines about when to choose one over the other here.)
Our gradual typing strategy is why we are going to disable noEmitOnError for now. With noEmitOnError set to true, our app would not build if there were any type errors, which would mean we wouldn't be able to poke around in our code via debugger as we are investigating our types during conversion.
Where do we start?
OK, so we know we can convert our app in a piecemeal fashion. So, where do we start? There are several strategies to choose from:
• Outer leaves first (aka Models first)—Models likely have the fewest non-Ember imports, so you won't have to use as many of our gradual typing hacks. This strategy is best if your app already uses Octane, since Octane getters might not always be compatible with pre-Octane computed properties. (👋👋 NOTE: see dependentKeyCompat, a whole 'nother can of worms).
• Inner leaves first (aka Components first)—This strategy is best if you are converting to Octane simultaneously with TypeScript. You will need to make heavy use of our gradual typing hacks.
• You touch it, you convert it—Whenever you are about to touch a file, convert it to TypeScript first. This strategy is best if you don't have time to convert everything at once.
• Most fun first—Pick the files you are most curious about. Refactoring to TypeScript is an awesome way to build confidence in your understanding of a chunk of code. This strategy is also great for onboarding new team members.
The Tilde team tried all of these strategies for our half-Classic/half-Octane app and settled on a mix of "you touch it, you convert it" and "most fun first." For our Super Rentals conversion, however, we are going to approach the conversion "outer leaves first."
Models
Our outer-most leaf is the Rental model. In JavaScript, it looks like this:
// app/models/rental.js
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
export default class RentalModel extends Model {
@attr title;
@attr owner;
@attr city;
@attr location;
@attr category;
@attr image;
@attr bedrooms;
@attr description;
get type() {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
The Rental model keeps track of various attributes about our vacation rentals. It also has a getter to categorize the type of rental into either "Community" or "Standalone."
Step One: Rename the file to TypeScript.
And...we're done! Congratulations! You've just written your first TypeScript class! Because all valid JavaScript is valid TypeScript, any JavaScript code will still compile as TypeScript code.
But...it looks like we have some type checking errors. We can see these errors automatically if we are using an editor with TypeScript integration, like VSCode, usually in the form of red squiggly underlines. Alternatively, you can run the TypeScript compiler manually in your terminal by running yarn tsc.
// app/models/rental.ts
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
export default class RentalModel extends Model {
// Member 'title' implicitly has an 'any' type.
@attr title;
// Member 'owner' implicitly has an 'any' type.
@attr owner;
// Member 'city' implicitly has an 'any' type.
@attr city;
// Member 'location' implicitly has an 'any' type.
@attr location;
// Member 'category' implicitly has an 'any' type.
@attr category;
// Member 'image' implicitly has an 'any' type.
@attr image;
// Member 'bedrooms' implicitly has an 'any' type.
@attr bedrooms;
// Member 'description' implicitly has an 'any' type.
@attr description;
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get type() {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
Ok, it looks like we have a little more work to do. The type checking errors indicate that TypeScript has found the potential for a bug here. Let's start from the top.
Member 'title' implicitly has an 'any' type.
This error is telling us that we need to annotate the title attribute with a type. We can look at the seed data from the Super Rentals app to figure out what the type should be. It looks like the title is a string.
// public/api/rentals.json
{
"data": [
{
"type": "rentals",
"id": "grand-old-mansion",
"attributes": {
"title": "Grand Old Mansion", // It's a string!
"owner": "Veruca Salt",
"city": "San Francisco",
"location": {
"lat": 37.7749,
"lng": -122.4194
},
"category": "Estate",
"image": "<https://upload.wikimedia.org/mansion.jpg>",
"bedrooms": 15,
"description": "This grand old mansion sits..."
}
},
// ...
]
}
@attr title: string;
Hmm...we have a new error now:
Property 'title' has no initializer and is not definitely assigned in the constructor.
This message is a little confusing, but here is what it means:
TypeScript expects properties to either:
• Be declared with an initial value (e.g. title: string = 'Grand Old Mansion')
• Be set in the constructor (e.g. constructor(title) { this.title = title; })
• Or be allowed to be undefined (e.g. title: string | undefined)
TypeScript doesn't really know that the @attr decorator is making the property exist. In this case, we can tell TypeScript "someone else is setting this property" by marking the value with the declare property modifier:
@attr declare title: string;
Let's go ahead and resolve the rest of the squiggly lines on the attributes. For the most part, our attributes use JavaScript primitive types. For the location attribute, however, we declared a MapLocation interface to describe the properties on the location object.
And the last error is coming from ESLint, asking us to provide a return type for the type getter. Because we know that the type getter will always return either the string 'Community' or the string 'Standalone', we can put string in as the return type, or we can be extra specific and use a union of literal types for the return value.
// app/models/rental.ts
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
interface MapLocation {
lat: number;
lng: number;
}
export default class RentalModel extends Model {
@attr declare title: string;
@attr declare owner: string;
@attr declare city: string;
@attr declare location: MapLocation;
@attr declare category: string;
@attr declare image: string;
@attr declare bedrooms: number;
@attr declare description: string;
get type(): 'Community' | 'Standalone' {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
Alright! We're free of type checking errors!
LET'S COMMIT!
One more thing about models before we move on. This model doesn't have any relationships on it, but if it did, we would use a similar strategy to what we did with attributes: the declare property modifier. The Ember Data types give us handy types that keep track of the many intricacies of Ember Data relationships. Cool!
import Model, {
AsyncBelongsTo,
AsyncHasMany,
belongsTo,
hasMany,
} from '@ember-data/model';
import Comment from 'my-app/models/comment';
import User from 'my-app/models/user';
export default class PostModel extends Model {
@belongsTo('user') declare author: AsyncBelongsTo<User>;
@hasMany('comments') declare comments: AsyncHasMany<Comment>;
}
Routes
The next leaf in includes routes. Let's convert the index route. It's pretty simple, with a model hook that accesses the Ember Data store and finds all of the rentals:
// app/routes/index.js
import Route from '@ember/routing/route';
import { service } from '@ember/service';
export default class IndexRoute extends Route {
@service store;
model() {
return this.store.findAll('rental');
}
}
First, we'll rename the file to TypeScript...and once again we have some type-checking errors:
// app/routes/index.ts
import Route from '@ember/routing/route';
import { service } from '@ember/service';
export default class IndexRoute extends Route {
// Member 'store' implicitly has an 'any' type.
@service store;
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
model() {
return this.store.findAll('rental');
}
}
The first error is Member 'store' implicitly has an 'any' type. We know that the type of the store service is a Store. We can import the Store type from '@ember-data/store' and add the type annotation.
@service store: Store;
And because the store is set by the @service decorator, we need to use the declare property modifier again.
@service declare store: Store;
And the last type-checking error is again the linter telling us we need a return type on the function. Here's a little hack you can use to check the return type. Pop void in as the return type. In this case, we get a type-checking error, as expected because we know the model hook does not actually return void :
// app/routes/index.ts
import Route from '@ember/routing/route';
import { service } from '@ember/service';
import Store from '@ember-data/store';
export default class IndexRoute extends Route {
@service store: Store;
// Type 'PromiseArray<any>' is not assignable to type 'void'.
model(): void {
return this.store.findAll('rental');
}
}
Hmm... PromiseArray makes sense, but I wouldn't expect an array of any values. It should be a more specific type. Something seems wrong here.
We've run into one of the first gotchas of using TypeScript with Ember. Ember makes heavy use of string key lookups. For example, here we look up all of the rentals by passing the 'rental' string to the Store's findAll method. In order for TypeScript to know that the 'rental' string correlates with the RentalModel, we need to add some boilerplate to the end of the rental model file. The ember-cli-typescript installation added a ModelRegistry for this purpose, and we just need to register our RentalModel with the registry:
// app/models/rental.ts
export default class RentalModel extends Model {/* ... */}
declare module 'ember-data/types/registries/model' {
export default interface ModelRegistry {
rental: RentalModel;
}
}
And now, we get a much more useful error!
// app/routes/index.ts
import Route from '@ember/routing/route';
import { service } from '@ember/service';
import Store from '@ember-data/store';
export default class IndexRoute extends Route {
@service store: Store;
// Type 'PromiseArray<RentalModel>' is not assignable to type 'void'.
model(): void {
return this.store.findAll('rental');
}
}
It looks like our return type is a Promise Array of Rental Models. We can add the appropriate imports and the type annotation, and now we have no more type-checking errors!
import Route from '@ember/routing/route';
import { service } from '@ember/service';
import Store from '@ember-data/store';
// FIXME: Do not merge with the "private" DS global exposed!
import DS from 'ember-data';
import RentalModel from 'super-rentals/models/rental';
export default class IndexRoute extends Route {
@service declare store: Store;
model(): DS.PromiseArray<RentalModel> {
return this.store.findAll('rental');
}
}
(NOTE: We have to use DS.PromiseArray for now because PromiseArray is private so the type isn't exported. We will fix this issue in a future commit. Let’s just keep this secret between us. 😛)
LET'S COMMIT!
Additionally, convert the Rental route.
Components
Next, let's try converting a component, the inner-most leaf of our app.
When choosing which components to convert first, I recommend choosing components that do not invoke any other components. The inner-most-inner-most leaf, if you will.
Additionally, we will convert each component in two passes:
1. For the first pass, we will address basic issues that one would find with tsc alone.
2. For the second pass, we will enable Glint for the component and address issues that arise from end-to-end type-checking.
We'll start with the Rentals::Filter component.
Rentals::Filter Component: TSC Pass
The Rentals::Filter component filters the list of vacation rentals based on a passed-in search query.
Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript [2022 Update]
When we rename the file, we see some type-checking errors:
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
export default class RentalsFilterComponent extends Component {
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get results() {
// Property 'rentals' does not exist on type '{}'.
// Property 'query' does not exist on type '{}'.
let { rentals, query } = this.args;
if (query) {
// Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
The first type-checking error is the linter reminding us to add a return type to the function. From reading the code, it looks like we are expecting this function to return an array of Rental models, so let's put that for now:
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
export default class RentalsFilterComponent extends Component {
get results(): Array<RentalModel> {
// Property 'rentals' does not exist on type '{}'.
// Property 'query' does not exist on type '{}'.
let { rentals, query } = this.args;
if (query) {
// Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
Alright! Next type-checking error:
Property 'rentals' does not exist on type '{}'.
We are destructuring the component args, but it looks like TypeScript has no idea what properties the args object should have. We have to tell TypeScript what the component arguments are.
Fortunately, the Glimmer Component type is a generic. It takes an optional type argument where you can specify the "component signature" as defined by Ember RFC-748 and polyfilled by Glint. To do this, we'll define an interface called RentalsFilterSignature with a field called Args to specify the component arguments. We'll mark the types for the arguments as unknown for now. Then, we can pass that interface as an argument to the Component type: Component<RentalsFilterSignature>.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
interface RentalsFilterSignature {
Args: {
rentals: unknown;
query: unknown;
};
}
export default class RentalsFilterComponent extends Component<RentalsFilterSignature> {
get results(): Array<RentalModel> {
let { rentals, query } = this.args;
if (query) {
// rentals: Object is of type 'unknown'.
// rental: Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
// Type 'unknown' is not assignable to type 'RentalModel[]'.
return rentals;
}
}
Now, TypeScript knows about our component's arguments, but it's complaining that because the rentals type is unknown, TypeScript doesn't know what to do with the filter method. Let's resolve these by adding a type to the rentals argument.
By doing a little sleuthing, tracing the component invocations back to the route template, we discover that the rentals argument is the resolved model from the IndexRoute.
<!-- app/components/rentals.hbs -->
<!-- ... -->
<!-- @rentals is passed into Rentals::Filter in the Rentals component -->
<Rentals::Filter @rentals={{@rentals}} @query={{this.query}} as |results|>
<!-- ... -->
</Rentals::Filter>
<!-- app/templates/index.hbs -->
<!-- ... -->
<!-- @rentals is passed into the Rentals component in the Index Route -->
<Rentals @rentals={{@model}} />
We can extract the resolved model type from the Index Route by using the ModelFrom utility type borrowed from the ember-cli-typescript documentation cookbook.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
import IndexRoute from 'super-rentals/routes';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsFilterSignature {
Args: {
rentals: ModelFrom<IndexRoute>;
query: unknown;
};
}
export default class RentalsFilterComponent extends Component<RentalsFilterSignature> {
get results(): Array<RentalModel> {
let { rentals, query } = this.args;
if (query) {
// query: Argument of type 'unknown' is not assignable to parameter of type 'string'.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
// Type 'ArrayProxy<RentalModel>' is missing the following properties from
// type 'RentalModel[]': pop, push, concat, join, and 45 more.
return rentals;
}
}
Updating the rentals type in the arguments interface resolves not only the type-checking error that we've been working on, but also another one further down in the code. Sweet!
Unfortunately, we have some new type-checking errors. These errors are telling us that the rentals argument returns an ArrayProxy<RentalModel> but filter is coercing it into an Array<RentalModel>, which has slightly different behavior. For example, ArrayProxy doesn't have push or pop methods like an Array does. This could cause a bug in the future! 🐛
We always want to return an Array, so we might resolve this by first converting the rentals argument to an Array before using it in the results getter:
let rentals = this.args.rentals.toArray();
Alternatively, we can convert the @rentals argument to an array in the model hook of the Index Route. Personally I prefer using this strategy when possible because:
1. We no longer need to import DS.
2. I find the behavior of PromiseArray to be confusing, so I prefer to convert it to an Array ASAP.
(NOTE: There are flaws with this strategy also, but I want to avoid changing the behavior from the original app, so we'll stick with this strategy for now.)
// app/routes/index.ts
import Store from '@ember-data/store';
import Route from '@ember/routing/route';
import { service } from '@ember/service';
import RentalModel from 'super-rentals/models/rental';
export default class IndexRoute extends Route {
@service declare store: Store;
async model(): Promise<Array<RentalModel>> {
return (await this.store.findAll('rental')).toArray();
}
}
And because we used the ModelFrom utility in our component arguments interface, we don't need to make any updates there because TypeScript already knows!
OK, we're down to one final type-checking error:
Argument of type 'unknown' is not assignable to parameter of type 'string'.
TypeScript is telling us that the includes method on the rental.title string expects a string to be passed to it, but we've passed an unknown. Let's find out what that query argument type actually is!
Just like with rentals, we can determine the type of query by looking at the component invocation in the Rentals component: @tracked query = '';
Alternatively, because we have noEmitOnError set to false in our tsconfig.json, we can also run our code and find the type of query via debugger or Ember Inspector.
It looks like query is a string, so we'll enter string into the Args field of our component signature.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalsComponent from 'super-rentals/components/rentals';
import RentalModel from 'super-rentals/models/rental';
import IndexRoute from 'super-rentals/routes';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsFilterSignature {
Args: {
rentals: ModelFrom<IndexRoute>;
query: string;
};
}
export default class RentalsFilterComponent extends Component<RentalsFilterSignature> {
get results(): Array<RentalModel> {
let { rentals, query } = this.args;
if (query) {
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
Phew! We're done!
LET'S COMMIT!
Rentals::Filter Component: Glint Pass
Up until now, we've been relying on the TypeScript compiler—tsc—for type-checking our TypeScript files only. Let's update the Glint configuration to include the files we've converted to TypeScript so far so that we can type-check the matching globs end-to-end:
# glintrc.yml
environment: ember-loose
include:
- 'app/models/**'
- 'app/routes/**'
- 'app/components/rentals/filter.*'
Now, we can run yarn glint in our terminal:
$ yarn glint
app/components/rentals/filter.hbs:1:1 - error TS2345: Argument of type '"default"' is not assignable to parameter of type 'unique symbol'.
1 {{yield this.results}}
In addition to tracking the types for the component arguments, the component signature also tracks the blocks we expect a component to yield. This (admittedly confusing) error message is telling us that we need to specify the Blocks field in our component signature so that Glint will know to expect us to yield a default block.
In our case, the Rentals::Filter component yields a block with an array of Rental models from the results getter. We can provide this information to Glint by adding the following to the component signature:
// app/components/rentals/filter.ts
// ...
interface RentalsFilterSignature {
Args: {/* ... */};
Blocks: { default: [results: Array<RentalModel>] };
}
export default class RentalsFilterComponent extends Component<RentalsFilterSignature> {/* ... */}
Now, whenever we invoke the Rentals::Filter component, Glint will require that we pass content to the default block. Glint will also provide type information in the invoking template about the yielded results value.
Once we've added the Blocks field, we can run yarn glint again and should see no errors.
LET'S COMMIT!
Map Component: TSC Pass
Next, let's take a look at the Map component, which displays a map of the given coordinates. First, we'll rename the file to TypeScript and take a look at the resulting type-checking errors:
// app/components/map.ts
import Component from '@glimmer/component';
import ENV from 'super-rentals/config/environment';
const MAPBOX_API = '<https://api.mapbox.com/styles/v1/mapbox/streets-v11/static>';
export default class MapComponent extends Component {
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get src() {
// Property 'lng' does not exist on type '{}'.
// Property 'lat' does not exist on type '{}'.
// Property 'width' does not exist on type '{}'.
// Property 'height' does not exist on type '{}'.
// Property 'zoom' does not exist on type '{}'.
let { lng, lat, width, height, zoom } = this.args;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get token() {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
Let's start by adding our arguments interface and resolving the return-type lints. We'll also need to add the type for MAPBOX_ACCESS_TOKEN to the config declaration file that ember-cli-typescript generated for us in our very first commit.
// app/config/environment.d.ts
export default config;
/**
* Type declarations for
* import config from 'my-app/config/environment'
*/
declare const config: {
// ...
MAPBOX_ACCESS_TOKEN: string;
};
// app/components/map.ts
import Component from '@glimmer/component';
import ENV from 'super-rentals/config/environment';
const MAPBOX_API = 'https://api.mapbox.com/styles/v1/mapbox/streets-v11/static';
interface MapArgs {
lng: unknown;
lat: unknown;
width: unknown;
height: unknown;
zoom: unknown;
}
export default class MapComponent extends Component<MapArgs> {
get src(): string {
let { lng, lat, width, height, zoom } = this.args;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
get token(): string {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
Look at that! All of our type-checking errors went away! For your first pass converting your app, I think it's totally fine to merge the unknown types like this. (It's way better than merging any.)
LET'S COMMIT!
Map Component: Glint Pass
Once again, we'll add this component's blob to the include key in our Glint configuration and run yarn glint.
# glintrc.yml
environment: ember-loose
include:
# ...
- 'app/components/map.*'
$ yarn glint
app/components/map.hbs:3:35 - error TS2345: Argument of type 'unknown' is not assignable to parameter of type 'EmittableValue | AcceptsBlocks<{}, any>'.
3 alt="Map image at coordinates {{@lat}},{{@lng}}"
~~~~~~~~
// ...
Starting from the top, we can see that Glint is less pleased with our unknown values than straight TypeScript was. We are seeing a lot of errors along the lines of Argument of type 'unknown' is not assignable to parameter of type 'EmittableValue | AcceptsBlocks<{}, any>'.
But Glint expects html attributes to have an EmittableValue passed to them. EmittableValue is defined as SafeString | Element | string | number | boolean | null | void; Unfortunately, it doesn't know if our unknown values match this type, so we'll have to investigate the types of our arguments.
We can reverse-engineering the types from one of the invocations:
<!-- example invocation -->
<Map
@lat={{@rental.location.lat}}
@lng={{@rental.location.lng}}
@zoom="9"
@width="150"
@height="150"
alt="A map of {{@rental.title}}"
/>
// app/components/map.ts
// ...
interface MapSignature {
Args: {
lng: number;
lat: number;
width: string;
height: string;
zoom: string;
};
}
export default class MapComponent extends Component<MapSignature> {/* ... */}
When we run yarn glint again, there is only one error remaining:
$ yarn glint
app/components/map.hbs:4:5 - error TS2345: Argument of type 'null' is not assignable to parameter of type 'Element'.
4 ...attributes
In addition to tracking your component's arguments and blocks, the component signature also keeps track of your component's "root element"—the element that receives "splattributes"— via the Element field. By default, the Element field type is set to null, indicating that ...attributes will not be allowed anywhere in the component template and invoking templates will not be allowed to pass any attributes to the component.
// app/components/map.hbs
<div class="map">
<img
alt="Map image at coordinates {{@lat}},{{@lng}}"
...attributes
src={{this.src}}
width={{@width}} height={{@height}}
>
</div>
In order to specify that the Map component splats its attributes onto an <img> element, we can add the Element field to the component signature, like so:
// app/components/map.ts
// ...
interface MapSignature {
Element: HTMLImageElement;
Args: {/* ... */};
}
export default class MapComponent extends Component<MapSignature> {/* ... */}
Now, when we run yarn glint, we get no errors.
LET'S COMMIT!
Remaining Inner-Most-Inner-Most Leaf Components
Using what we've learned, convert the rest of the inner-most-inner-most components (components that do not invoke any other components):
Rentals Component: TSC Pass
Our last un-converted component is the Rentals component, which takes an array of Rental models, passes them into the Rentals::Filter component along with a filter query, then renders a Rental component for each of the yielded results.
When we rename the file, we see no type-checking errors because the class itself is pretty simple:
// app/components/rental.ts
import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
export default class RentalsComponent extends Component {
@tracked query = '';
}
LET'S COMMIT!
Rentals Component: Glint Pass
Next, we enable Glint for the component:
# .glintrc.yml
environment: ember-loose
include:
# ...
- 'app/components/rentals.*'
Then run yarn glint and see one error:
$ yarn glint
app/components/rentals.hbs:8:34 - error TS2339: Property 'rentals' does not exist on type 'EmptyObject'.
8 <Rentals::Filter @rentals={{@rentals}} @query={{this.query}} as |results|>
~~~~~~~
This error is telling us that Glint doesn't yet know about the rentals argument. Let's add that to our component signature. (We already know the type from our investigation for the Rentals::Filter component!)
// app/components/rentals.ts
import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import IndexRoute from 'super-rentals/routes/index';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsSignature {
Args: {
rentals: ModelFrom<IndexRoute>;
};
}
export default class RentalsComponent extends Component<RentalsSignature> {/* ... */}
Now, yarn glint gives us no errors!
LET'S COMMIT!
Are we done yet?
Remember that when we set up glint, we included a catch-all "template registry" so that we won't be bombarded with errors during our conversion. Now that we've converted every component with a class file, it's time to remove that catch-all. 🙈
// types/super-rentals/index.d.ts
// ...
import '@glint/environment-ember-loose';
// NOTE: This import won't be necessary after Glint 0.8
import '@glint/environment-ember-loose/native-integration';
// Delete this:
// declare module '@glint/environment-ember-loose/registry' {
// export default interface Registry {
// [key: string]: any;
// }
// }
// ...
Now, let's run yarn glint again:
$ yarn glint
app/templates/rental.hbs:1:1 - error TS7053: Element implicitly has an 'any' type because expression of type '"Rental::Detailed"' can't be used to index type 'Globals'.
Property 'Rental::Detailed' does not exist on type 'Globals'.
1 <Rental::Detailed @rental={{@model}} />
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// ...
We are inundated with errors following the pattern: Element implicitly has an 'any' type because expression of type 'X' can't be used to index type 'Globals'. This error means that you need to register X in your "template registry."
Template Registry
In order for Glint to be able to find the correct component (or helper or modifier) for a template invocation, we need to register each one with Glint's template registry, similar to how we need to register our models. (NOTE: once RFC-779 is implemented, you will no longer need to do this. 🙌)
Add a registration to the bottom of each component class file, like so:
// app/components/rentals/filter.ts
// ...
export default class RentalsFilterComponent extends Component<RentalsFilterArgs> { /* ... */ }
declare module '@glint/environment-ember-loose/registry' {
export default interface Registry {
'Rentals::Filter': typeof RentalsFilterComponent;
}
}
Learn more about the template registry in the Glint documentation.
LET'S COMMIT!
Now, when we run yarn glint most of the errors are gone. Unfortunately, we still have an error of this type for each template-only component. 😢
Registering Template-Only Components
When we registered our components earlier, we only registered the components that already had classes. Glint requires that you also register template-only components so that there are no gaps in the type-checking.
The Glint team recommends adding a TypeScript file for the component with import templateOnlyComponent from @ember/component/template-only; and adding the relevant boilerplate as shown in the Glint documentation.
At Tilde, we prefer to add an empty Glimmer component class. 😬 While there are minor performance gains from using template-only components, we find that these are outweighed by the cost of having to teach developers the templateOnlyComponent function, which was always meant to be an intimate API. Additionally, we found that eventually we were adding backing classes to many template-only components anyway, and the churn necessary to re-write the component file when this happened was annoying.
So, pick the method that works the best for your team and app. With that said, once RFC-779 is implemented, you will no longer need to worry about this issue. 🙌 🙌
Let's go ahead and add empty component classes and their relevant component signatures for our template-only components. Here's the Rental component as an example:
// app/components/rental.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
interface RentalSignature {
Args: { rental: RentalModel };
}
export default class RentalComponent extends Component<RentalSignature> {}
declare module '@glint/environment-ember-loose/registry' {
export default interface Registry {
Rental: typeof RentalComponent;
}
}
We can also now remove the include config from our .glintrc.yml.
And now, when we run yarn glint, there are no errors! We're done converting our app! 🎉
LET'S COMMIT!
Continuous Integration
Last but not least, we should enable type-checking in CI so that we won't accidentally merge future code with TypeScript/Glint errors:
// package.json
{
"name": "super-rentals",
// ...
"scripts": {
"lint:glint": "glint",
// ...
},
// ...
}
Because Ember's default lint script aggregates all of the other lint:xxx scripts, our lint:glint script should be included when lint is run from now on, including on CI.
LET'S COMMIT!
Wrapping Up
Thanks for following along with this tutorial. If you want to see the full diff for the conversion, head on over to the PR here:
Convert to TypeScript (2022 Edition) by gitKrystan · Pull Request #1 · gitKrystan/super-rentals-ts-2022
Converting the Ember Super Rentals app to TypeScript (2022 Edition) - Convert to TypeScript (2022 Edition) by gitKrystan · Pull Request #1 · gitKrystan/super-rentals-ts-2022
Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript [2022 Update]
If you have any questions or comments about this tutorial, feel free to comment on the PR!
FAQs
What if I want to write new code in TypeScript?
Unfortunately, the blueprints that ship with ember-cli-typescript are perpetually out-of-date with the latest ember-source blueprints. In fact, I recommend removing the ember-cli-typescript-blueprints package from your project altogether.
With that said, thanks to this PR, if you are running ember-cli >= 4.3 and ember-source >= 4.4 (now in beta), you can generate TypeScript code using Ember's built-in blueprints by running, for example, EMBER_TYPESCRIPT_BLUEPRINTS=true ember g component example -gc --typescript
Eventually the EMBER_TYPESCRIPT_BLUEPRINTS flag will no longer be necessary. Also, you will be able to set "isTypeScriptProject": true in .ember-cli to make the --typescript flag your default.
I'm really excited about the implications of RFC-779 for TypeScript users. Is there a way I can try it?
Ember RFC-779 introduces a new .gts file type that allows you to write <template> tags in your TypeScript code instead of a separate .hbs template file. Additionally, instead of using a runtime resolution strategy that looks up your components, etc, using magic strings, your <template> code will have access to values in your JavaScript scope, which means they can just use normal JavaScript imports. This means you will no longer have to add that annoying boilerplate "template registry" code at the end of all you component, modifier, and helper files. Additionally, template-only components will no longer be a special case requiring the additional thought we put into them above.
If you're excited to try it, you can! Just install ember-template-imports and have fun removing all of that annoying boilerplate.
Alternatively, check out the source for ember-wordle, which uses ember-template-imports and the <template> tag. 🤯
Do you have any sweet tricks for type narrowing in Ember?
Why, yes! Yes I do! You may already be familiar with Ember debug's assert. This function will throw an error with the provided message if the provided condition is false. Also, the type for assert is written such that TypeScript now knows that the condition must be true for all of the following lines. This allows us to use assert for type "narrowing". Also, the best part is that the assert code and its condition are stripped from your production builds, so you haven't added any production overhead. Sweet!
How can I use TypeScript with Ember Concurrency?
Picture a simple Ember Concurrency task. When you perform the waitASecond task, it waits for a second, then logs 'done' to the console.
// my-app/components/waiter.js
import { action } from '@ember/object';
import Component from '@glimmer/component';
import { task, timeout } from 'ember-concurrency';
export default class Waiter extends Component {
@task *waitASecond() {
yield timeout(1000);
console.log('done');
}
@action startWaiting() {
this.waitASecond.perform();
}
}
Unfortunately, TypeScript doesn't know much about what the generator is doing to the waitASecond generator function, so it doesn't know that waitASecond is actually a Task that you can call perform on. To use Ember Concurrency with TypeScript, we need to use an add-on called ember-concurrency-ts, which gives us a taskFor method that casts the TaskGenerator as a Task:
// my-app/components/waiter.ts
import { action } from '@ember/object';
import Component from '@glimmer/component';
import { task, timeout, TaskGenerator } from 'ember-concurrency';
import { taskFor } from 'ember-concurrency-ts';
export default class Waiter extends Component {
@task *waitASecond(): TaskGenerator<void> {
yield timeout(1000);
console.log('done');
}
@action startWaiting(): void {
taskFor(this.waitASecond).perform();
}
}
How can I use TypeScript with Mirage?
One of the biggest sticking points we had with TypeScript conversion was converting test files that use Mirage.
MirageJS, which powers ember-cli-mirage, does have types, but we ran into issues using them with ember-cli-mirage without lots of really complicated gymnastics that won't fit in this blog post. To that end, I am posting a GitHub gist with our gymnastics, which will hopefully be helpful to you. (NOTE: If you are a TypeScript beginner, it's OK to be overwhelmed reading the types in that gist. It was certainly overwhelming writing them! ❤️)
What if I have deeply nested gets?
Very occasionally, you still need to use get (for proxies), even with Ember Octane. If your get call is accessing a deeply nested property, however, you will need to chain your get calls together. This is because TypeScript doesn't know to split the string lookup on dots. In practice, I haven't found that this comes up super often, and often, you don't actually need get for the entire chain.
// This gives you a confusing type-checking error:
myEmberObject.get('deeply.nested.thing');
// Do one of these instead:
myEmberObject.get('deeply').get('nested').get('thing');
myEmberObject.deeply?.nested?.get('thing');
myEmberObject.deeply?.get('nested').thing;
TypeScript Without TypeScript
No appetite for switching? You can get some of TypeScript's benefits—such as code completion and documentation-on-hover—by using JSDoc annotations in your JavaScript along with the VSCode text editor. JSDoc allows you to document types, though it doesn't have all of TypeScript's features.
VSCode's JavaScript IntelliSense features are powered by the TypeScript compiler under the hood, so you even get access to TypeScript's built-in types and @types packages for your libraries, even if you don't use JSDoc annotations.
Once you've documented the types in your JavaScript files, you can even add a @ts-check comment to the top of your file to get type checking in your JavaScript files, powered by TypeScript!
Moving on
In the next article, we'll talk about the benefits of TypeScript in the context of developer confidence.
]]>
<![CDATA[Parallelizing Queries with Rails 7's `load_async`]]>https://blog.skylight.io/rails-7-load_async/62016c8b60e2c4003bc6eae9Wed, 09 Feb 2022 22:46:21 GMTAs you're likely well aware, Rails 7 was released last month bringing a number of new features with it. One of the features we're most excited about is load_async. This features allows for multiple Active Record queries to be executed in parallel which can be a great tool for speeding up slow requests.
Since Rails introduces an entirely new infrastructure for load_async, Skylight's existing integration wasn't capturing all of these queries. But don't worry, because the brand new Skylight 5.3 handles these correctly!
To see how this works in practice, consider the following scenario:
class UsersController < ApplicationController
def index
@users = User.slow.all
@apps = App.slow.all
@invoices = Invoice.slow.all
end
end
app/controllers/users_controller.rb
<h1>Users</h1>
<ul>
<%- for user in @users -%>
<li><%= user.name %></li>
<%- end -%>
</ul>
<h1>Apps</h1>
<ul>
<%- for app in @apps -%>
<li><%= app.title %></li>
<%- end -%>
</ul>
<h1>Invoice</h1>
<ul>
<%- for invoice in @invoices -%>
<li><%= invoice.amount %></li>
<%- end -%>
</ul>
app/views/users/index.html.erb
This is a pretty straightforward example, but let's break down how Rails will process it. When /users is requested, we'll enter the UsersController#index action. This will initialize our three instance variables, but the queries will not actually be executed until the results are needed.
💡
Note that we're using a custom scope called slow. This simulates a slow query with pg_sleep like such: scope :slow, -> { where("SELECT true FROM pg_sleep(1)") }
Once Rails begins rendering the view it will hit the @users for loop. It will attempt to coerce @users to an array by calling to_a . This causes the query to execute synchronously, meaning that we'll have to wait for the query to complete before rendering can progress. Once the query has executed we'll continue on, repeating the process for @apps and @invoices.
Here's what it looks like in Skylight:
Event sequence without load_async
Unsurprisingly, the bulk of our time is spent in these very slow queries which each take a full second to execute with the entire request taking over 3 seconds total.
We could try to change things by calling to_a in the controller action instead as such:
@users = User.slow.all.to_a
@apps = App.slow.all.to_a
@invoices = Invoice.slow.all.to_a
Event sequence with to_a
However, this only moves the work slightly earlier in the process. We still won't see any performance benefits since each query still has to execute sequentially. In general, calling to_a like this isn't recommended.
Enter load_async
As you probably guessed, load_async is going to help solve this problem. Using load_async we can rewrite this as:
@users = User.slow.all.load_async
@apps = App.slow.all.load_async
@invoices = Invoice.slow.all.load_async
When load_async is called, the query starts executing immediately on a global thread pool. So in our example, all three queries will execute in parallel. When we hit the view, we'll still have to wait for @users to be loaded, but while we're waiting, @apps and @invoices are also loading. Once we hit those in the rendering process they'll either already be loaded or at least well on their way there!
Event Sequence with load_async
We can see that this is indeed what happened. We're still blocked on the users query since we didn't actually make it any faster, but we can see that we no longer have to wait for the apps or invoices queries. Our total request now only takes a bit over 1 second, which is a significant improvement.
💡
Before this will work, you do need to configure the thread pool executor. This can be done in your Rails application config by setting config.active_record.async_query_executor to :global_thread_pool. There are a handful of other options so it's worth taking a look at the Rails documentation
A Word of Warning
If we still want to make this request faster—and we should since 1 second response time is still pretty bad!— then we could work on speeding up the users query.
Event Sequence with optimized users query
Unfortunately, this really any better and our whole request still takes over 1 second to complete. So what happened?
As before, the queries all executed in parallel. However, the apps query is still slow so even though our users query finished much faster we still end up blocked waiting for the apps query to finish.
As with almost all performance optimizations, load_async isn't a panacea. We're still only going to be as fast as our slowest query. However, as we saw in our initial work, there can still be big benefits by running this queries sequentially.
One Final Detail
One important configuration option I didn't mention was the concurrency option. By default the global executor that we configured will only execute a maximum of 4 queries simultaneously. When the pool is full, the queries become synchronous, behaving as they would if load_async was not used. Having a low default is good to ensure that your database isn't overloaded, but if your database can handle the additional connections and load it may be worth increasing this value with config.active_record.global_executor_concurrency. (Check out the documentation for the correct options if you're using an alternate pool.)
Conclusion
While load_async won't solve all your performance problems, it's definitely something you should consider in any case where you have multiple sequential queries. As we saw, running queries simultaneously can bring significant benefits over running them sequentially. Enjoy your new found performance optimizing potential!
]]>
<![CDATA[Introducing Saved Searches]]>https://blog.skylight.io/introducing-saved-searches/6095bee79843a7003bdbc4fbFri, 14 May 2021 21:55:17 GMT
Tired of composing the same endpoint searches over and over while working on performance issues? We've got you covered with our new Saved Searches feature! It allows you to bookmark your commonly used endpoint searches by app, so instead of having to remember an exact query, you can just save it so you don't have to sift through your endpoints list again. It's just another way we try to help our users get answers, not just a bunch of data.
Introducing Saved Searches
Need some help with a particular performance issue and want to share it with a colleague? Searches are shared with all collaborators on an app, so just save the query and you can easily show your coworker exactly what you were looking at.
Have a number of apps, each with their own performance problems to focus on? Because searches are unique to each environment (e.g. "development" or "production") and component (e.g. "web" or "worker"), you can use them to track what you're working on so only the relevant saved searches will be there when you meander over to a particular app dashboard before you've had your coffee.
Demoing your work to your colleagues? Instead of awkwardly composing your query while they watch, just save that puppy ahead of time.
Here at Skylight we believe it's the little things that make a big difference in user experience. I hope this small feature will make your experience of using Skylight just a bit snazzier and speedier.
Introducing Saved Searches
Take a look at our guides to see it in action. And as always, we love to hear from our users, so please reach out with any feedback.
If you're just here for the feature announcement, you're now free to go, but read on if you'd like to hear about what I've learned from bringing this feature to fruition.
Personal Takeaways
If you're a member of our Insiders mailing list, you may already know that this was the first time I've managed a feature on my own here at Tilde (or without a project manager) and let me tell you, I've learned a lot.
First, I've gained a greater appreciation for what project managers do. When I worked at a company with a PM I'd honestly get a bit PO'ed when a ticket did not define the full scope of what they were expecting, or the designs didn't include all the states of a feature. Ah, how the tables have turned. This project taught me how difficult it is to fully plan a feature ahead of time, even a small one, and why there is such an iterative nature to programming. So maybe go a little easier on your project manager. 😉
Second, managing this feature helped give me more confidence in my software development skills and my ability to figure something out that might seem way over my head at first. It also helped me appreciate where I am in my software development journey more. Here are the things that I think really helped me get there:
Learn what works for you to get yourself unstuck
I discovered that often my biggest problem is that my question is just too vague, and the standard advice of talking to a rubber duck was just not cutting it. So I have a sort of rubber duck penpal instead. Before you think I'm just irredeemably weird (I mean, I do live in a city whose slogan is "Keep Portland Weird", so I guess I can't count that out), let me explain.
I've learned that I process things better through writing than talking. So I started writing out my questions as inline code comments just for me to see, which was, let's just say, eye opening. When I read the first question I write down my first reaction is a lot less "Great question!" and a lot more "I'm sorry, was that a thought?".
Introducing Saved Searches
Seeing it written out seems to trick my brain into thinking that someone else is asking me the question and, well, if someone else is asking, I really ought to try to clarify it and answer it, right? This leads me to ask myself narrowing questions that I also write down, and eventually I make my question so specific that I can figure out the answer by going to the documentation or googling it. As a bonus, if I'm still stuck, I can go to a colleague with this more specific question and it makes it a lot easier for them to help me. I'm not saying I do this all the time yet, but now it's what I strive to do, at least.
You will throw out work and, no, it was not a waste of time
Sometimes you're refactoring a bit of code and realize at some point that it's not working out. Or it might be that a design seemed good in the abstract but it doesn't integrate well with the rest of the feature when you see it in action. At that point it's often better to throw out that work and start over with the knowledge you gained from your first attempt. As far as I can tell, this is just... programming. You know, I'm not sure why I ever expected I should be able to write code that works exactly the way I want the first time. Literally nobody does that all the time or even most of the time.
Dive in and learn what's right in front of you
I am a recovering perfectionist and former straight A student who thought that was the be all end all of being a competent human being. I was always looking for that ⭐️. And so I've spent my development career stressing over the specific skills I need to develop to finally be a real web developer.
🙄
But there is no single source of truth to tell you what skills a web developer needs to have because our field is so new and ever-changing. And it’s not like you can just download "web developer" as a skill.
Introducing Saved Searches
It's more like you're walking on a path and each time you go over it you notice and learn different things and deepen your knowledge. Eventually you work on enough of a variety of things that you learn how stuff fits together and you see more of the nuances. And one day you look up and discover that you know where to look when various problems come up. It's not some big goal of being a competent developer or some big picture skills blueprint that gets you there. It's immersing yourself in each problem you come across, reading the relevant documentation, and honing your questions to build better understanding over time. So have a little patience with yourself and just dig in.
]]>
<![CDATA[Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript]]>https://blog.skylight.io/ts-extends-confidence-3/605cff76f63ddf003bd1dbf3Tue, 30 Mar 2021 15:10:00 GMT
This article is the third and final part of a series on converting your Ember app to TypeScript to foster confidence in your engineering team, based on my talk for EmberConf 2021.
We started with some basics: "What even is a type? What is TypeScript?" Then, we looked at what TypeScript looks like in an Ember app. Now, we're circling back to the benefits of TypeScript in the context of developer confidence.
Sus? How do we become "imposters"?
The prizewinning author Maya Angelou once said, after publishing her 11th book, that every time she wrote another one she’d think to herself: “Uh-oh, they’re going to find out now. I’ve run a game on everybody, and they're going to find me out.”
Imposter syndrome is "the experience of feeling incompetent and of having deceived others about one's abilities". You will find "imposters" in all facets of society, regardless of culture, gender, age, or occupation. In fact, psychologists estimate that 70% of people will experience this feeling at least once in their lives.
Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript
70% of us are imposters?
To call it a syndrome is to downplay how universal it is. -What is imposter syndrome and how can you combat it?
To that end, the psychologists who first described this experience didn't call it "imposter syndrome," they called it imposter phenomenon.
Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript
There are all sorts of reasons why you might experience imposter phenomenon. Studies show that the more competent someone is in a subject area, the more likely they are to underestimate their own ability compared to their peers. So, it's not an issue of competence, it's an issue of confidence.
It me!
I am one of these imposters.
I am a programmer from a non-traditional background. I didn't realize I was interested in computers until I was 30. Instead, I became a designer. I spent most of my architectural career designing buildings and urban landscapes for tech companies in silicon valley. You might even recognize my work. 💁♀️
My exposure to tech companies led to curiosity about programming. Drawn by the lure of an equally interesting but less stressful career, I left architecture and attended a code school here in Portland, where I learned Ember among other things. It was awesome! I was so stoked to get my new career started. One evening, I recruited some code school colleagues to join me at the local JavaScript Meetup. The Meetup turned out to be a bit of a dud, but by a stroke of good fortune, in walked a giant crowd of people, all clad in Ember gear. It turned out that an impromptu EmberConf Happy Hour had arrived!
Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript
Despite being super nervous, I did the best I could networking and met a crowd of very nice folks. But one conversation stuck with me the most. A man, after bragging about having graduating with his computer science degree the year I was born, tried to convince me that code school was a bad idea because the market was oversaturated with junior developers. He then proceeded to give my male code school colleagues sage career advice.
🤔 I started to think "Maybe I don't belong here?"
Nevertheless she persisted
I finished code school and started a hobby app. At our school's showcase demo day, I presented my hobby app to potential employer after potential employer, but one interaction in particular stuck out.
Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript
I recognized Yehuda Katz from across the room and got a little nervous. He's like...the guy that wrote thing thing, right?
I stumbled through my presentation, then Yehuda and his team had great questions and suggestions. Less than an hour later, I had a very flattering email in my inbox, and I've been working at Tilde ever since.
And yet...I still felt like an imposter. Mr. CS Degree was still in my head.
And then...2020 happened
Three years into my journey at Tilde, 2020 happened. Our company moved to fully-remote overnight. Rather than try to push through our big projects while still reeling from this massive change, we decided to focus instead on small, relaxing projects as we adapted to these new norms.
Just a few months prior, the Ember team had released Ember Octane. We decided that if we are going to convert our app to Octane anyway, we might as well convert it to TypeScript at the same time. Godfrey gave us a TypeScript demo, and we were off.
At first, I felt a little overwhelmed, but eventually, as we worked our way through the app, I started to really see the benefits of TypeScript. I found myself drawn to working in the more complex—sometimes crufty—areas of our codebase, code that had intimidated me before. Beyond transforming our codebase, I myself was starting to feel transformed... from a competent but hesitant mid-level engineer into a competent and confident senior engineer. I was starting to feel less like an imposter.
Can we fix it? Yes we can!
Imposter phenomenon is talked about quite a bit in the programming community, and there is lots of wonderful advice to be found:
1. Surround yourself with supportive people.
2. Own your accomplishments.
3. Learn to take your mistakes in stride.
4. See yourself as a work in progress.
5. Train yourself not to need external validation.
6. Realize there's no shame in asking for help.
7. Use positive affirmations.
8. Say "yes" to opportunities.
9. Visualize success.
10. Go to therapy.
11. Do some yoga.
12. Embrace feeling like an imposter.
13. Decide to be confident.
14. Etc, etc, etc.
It can be a long and overwhelming TODO list, and rarely are technical and tooling solutions offered. Based on my experience, I propose adding one more item here:
Typed Ember extends Confidence Part 3: The Real Benefits of TypeScript
The real benefits of TypeScript
If you google "Why use TypeScript", you can find all sorts of blogs about TypeScript's technical benefits, and sure, there are many. But to me, where TypeScript really shines is not its technical, but its "personal" benefits.
Confidence to refactor the crufty stuff
Many legacy code bases have code that people are scared to work on. I've found that refactoring to TypeScript makes understanding these crufty spots so much easier, and sometimes even fun.
Confidence that your code will Just Work
Once you've added types to a significant chunk of your project, you really start to see the benefits. Type annotations, coupled with JSDoc, are a place to pool the knowledge of every engineer that ever worked on that code. Eventually, you start to notice that you don't have to refresh your development app so many times to experiment because your code Just Works the first time around.
Confidence to open PRs on open source projects
I used to be scared to open pull requests on open source projects because it felt too public and unsafe. Opening PRs on the Ember Types on Definitely Typed was a great way to get started in open source, and I've since moved on to opening PRs on other projects too.
Confidence to try other Strictly Typed languages
I've been to RustConf like four times, and each time I take the beginner and intermediate trainings and still feel totally overwhelmed. After using TypeScript for only a few months, I was able to transition to writing Rust, and it made so much more sense. I will forever refer to TypeScript as "Baby's First Type System."
Confidence to make you read this series of articles
TypeScript's answer key gives me confidence. So much so that I signed up to do an EmberConf talk after years of saying "Maybe one day..." and now you've read these articles about it. And for that, I thank you.
]]>
<![CDATA[Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript]]>https://blog.skylight.io/ts-extends-confidence-2/605cfc07f63ddf003bd1db87Tue, 30 Mar 2021 15:05:00 GMT
This article is part 2 of a series on converting your Ember app to TypeScript to foster confidence in your engineering team, based on my talk for EmberConf 2021.
I've updated this tutorial in 2022 based on the latest and greatest. I recommend reading that version instead!
We started with some basics: "What even is a type? What is TypeScript?" Now, we'll look at what TypeScript looks like in an Ember app before circling back to the benefits of TypeScript in the context of developer confidence.
A Metatutorial
Let's convert an app to TypeScript! We'll use the Super Rentals app from the Ember Guides tutorial as our example. Super Rentals is a website for browsing interesting places to stay during your post-quarantine vacation.
Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript
Super Rentals is a very modern Ember app, using the latest and greatest Ember Octane features. Admittedly, using TypeScript with pre-Octane Ember was clunky. With Octane and native classes, however, using TypeScript with Ember is pretty straightforward.
If you are not familiar with Ember Octane idioms, I recommend following the Super Rentals tutorial before following this one. Otherwise, you can start with:
$ git clone <https://github.com/ember-learn/super-rentals.git> && cd super-rentals
Installing TypeScript
The first step is to run ember install ember-cli-typescript. Installing the ember-cli-typescript package adds everything you need to compile TypeScript.
$ ember install ember-cli-typescript
🚧 Installing packages…
ember-cli-typescript,
typescript,
@types/ember,
@types/ember-data,
Etc…
create tsconfig.json
create app/config/environment.d.ts
create types/super-rentals/index.d.ts
create types/ember-data/types/registries/model.d.ts
create types/global.d.ts
This includes:
• The typescript package itself.
• A default tsconfig.json file.
• Some basic utility types and directories.
• And types packages for each of Ember's modules.
While Ember itself doesn't have types baked in (spoiler alert: yet), there is a project called Definitely Typed that acts as a repository for types for hundreds of projects—including Ember. You install these types as packages, then import them the same way you would a JavaScript module.
LET'S COMMIT!
Gradual Typing Hacks
Alright! Now that we have installed TypeScript, we can start converting files. Fortunately, TypeScript allows for gradual typing. This means that you can use TypeScript and JavaScript files interchangeably, so you can convert your app piecemeal.
Of course, many of your files might reference types in other files that haven't been converted yet. There are several strategies you can employ to avoid a chain-reaction resulting in having to convert your entire app at once:
TypeScript declaration files (.d.ts)—These files are a way to document TypeScript types for JavaScript files without converting them.
The unknown type—You can sometimes get pretty far just by annotating types as unknown.
The any type—Opt out of type checking for a value by annotating it as any.
The @ts-expect-error directive—A better strategy than any, however, is to mark offending parts of your code with a @ts-expect-error directive. This comment will ignore a type-checking error and allow the TypeScript compiler to assume that the value is of the type any. If the code stops triggering the error, TypeScript will let you know.
(Experienced TypeScript users may already be familiar with @ts-ignore. The difference is that @ts-ignore won't let you know when the code stops triggering the error. At Tilde, we've disallowed @ts-ignore in favor of @ts-expect-error. If you really want to dig into it, the TypeScript team provided guidelines about when to choose one over the other here.)
Gradual Strictness, or How I Learned to Stop Worrying and Love the Strictness
You can also gradually increase TypeScript's strictness, as we mentioned before. There are two ends of the spectrum here:
Start with all the checks disabled, then enable them gradually as you start to feel more comfortable with your TypeScript conversion. I do recommend switching to strict mode as soon as possible because strictness is sorta the point of TypeScript to avoid shipping detectable bugs in your code.
// tsconfig.json
{
"compilerOptions": {
"alwaysStrict": true,
"noImplicitAny": true,
"noImplicitThis": true,
"strictBindCallApply": true,
"strictFunctionTypes": true,
"strictNullChecks": true,
"strictPropertyInitialization": true,
// ...
}
}
Alternatively, you can start in strict mode. This is the strategy we will use for converting Super Rentals, since I want you to see the full power of TypeScript.
// tsconfig.json
{
"compilerOptions": {
"strict": true,
// ...
}
}
In fact, I want my TypeScript even stricter. I'm going to also add the typescript-eslint plugin, which adds additional checks:
yarn add -D @typescript-eslint/parser @typescript-eslint/eslint-plugin
(👋👋 NOTE: Plus some boilerplate.)
LET'S COMMIT!
Where do we start?
OK, so we know we can convert our app in a piecemeal fashion. So, where do we start? There are several strategies to choose from:
• Outer leaves first (aka Models first)—Models likely have the fewest non-Ember imports, so you won't have to use as many of our gradual typing hacks. This strategy is best if your app already uses Octane, since Octane getters might not always be compatible with computed properties. (👋👋 NOTE: see dependentKeyCompat, a whole 'nother can of worms).
• Inner leaves first (aka Components first)—This strategy is best if you are converting to Octane simultaneously with TypeScript. You will need to make heavy use of our gradual typing hacks.
• You touch it, you convert it—Whenever you are about to touch a file, convert it to TypeScript first. This strategy is best if you don't have time to convert everything at once.
• Most fun first—Pick the files you are most curious about. Refactoring to TypeScript is an awesome way to build confidence in your understanding of a chunk of code. This strategy is also great for onboarding new team members.
The Tilde team tried all of these strategies for our half-Classic/half-Octane app and settled on a mix of "you touch it, you convert it" and "most fun first." For our Super Rentals conversion, however, we are going to approach the conversion "outer leaves first."
Models
Our outer-most leaf is the Rental model. In JavaScript, it looks like this. The Rental keeps track of various attributes about our vacation rentals. It also has a getter to categorize the type of rental into either "Community" or "Standalone."
// app/models/rental.js
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
export default class RentalModel extends Model {
@attr title;
@attr owner;
@attr city;
@attr location;
@attr category;
@attr image;
@attr bedrooms;
@attr description;
get type() {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
Step One: Rename the file to TypeScript.
And...we're done! Congratulations! You've just written your first TypeScript class! Because all valid JavaScript is valid TypeScript, any JavaScript code will still compile as TypeScript code. But...it looks like we have some type checking errors:
// app/models/rental.ts
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
export default class RentalModel extends Model {
// Member 'title' implicitly has an 'any' type.
@attr title;
// Member 'owner' implicitly has an 'any' type.
@attr owner;
// Member 'city' implicitly has an 'any' type.
@attr city;
// Member 'location' implicitly has an 'any' type.
@attr location;
// Member 'category' implicitly has an 'any' type.
@attr category;
// Member 'image' implicitly has an 'any' type.
@attr image;
// Member 'bedrooms' implicitly has an 'any' type.
@attr bedrooms;
// Member 'description' implicitly has an 'any' type.
@attr description;
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get type() {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
Ok, it looks like we have a little more work to do. The type checking errors indicate that TypeScript has found the potential for a bug here. Let's start from the top.
Member 'title' implicitly has an 'any' type.
This error is telling us that we need to annotate the title attribute with a type. We can look at the seed data from the Super Rentals app to figure out what the type should be. It looks like the title is a string.
// public/api/rentals.json
{
"data": [
{
"type": "rentals",
"id": "grand-old-mansion",
"attributes": {
"title": "Grand Old Mansion", // It's a string!
"owner": "Veruca Salt",
"city": "San Francisco",
"location": {
"lat": 37.7749,
"lng": -122.4194
},
"category": "Estate",
"image": "<https://upload.wikimedia.org/mansion.jpg>",
"bedrooms": 15,
"description": "This grand old mansion sits..."
}
},
// ...
]
}
@attr title: string;
Hmm...we have a new error now:
Property 'title' has no initializer and is not definitely assigned in the constructor.
This message is a little confusing, but here is what it means:
TypeScript expects properties to either:
• Be declared with an initial value (e.g. title: string = 'Grand Old Mansion')
• Be set in the constructor (e.g. constructor(title) { this.title = title; })
• Or be allowed to be undefined (e.g. title: string | undefined)
TypeScript doesn't really know that the @attr decorator is making the property exist. In this case, we can tell TypeScript "someone else is setting this property" by marking the value with the declare property modifier:
@attr declare title: string;
Let's go ahead and resolve the rest of the squiggly lines on the attributes. For the most part, our attributes use JavaScript primitive types. For the location attribute, however, we declared a MapLocation interface to describe the properties on the location object.
And the last error is coming from ESLint, asking us to provide a return type for the type getter. Because we know that the type getter will always return either the string 'Community' or the string 'Standalone', we can put string in as the return type, or we can be extra specific and use a union of literal types for the return value.
// app/models/rental.ts
import Model, { attr } from '@ember-data/model';
const COMMUNITY_CATEGORIES = ['Condo', 'Townhouse', 'Apartment'];
interface MapLocation {
lat: number;
lng: number;
}
export default class RentalModel extends Model {
@attr declare title: string;
@attr declare owner: string;
@attr declare city: string;
@attr declare location: MapLocation;
@attr declare category: string;
@attr declare image: string;
@attr declare bedrooms: number;
@attr declare description: string;
get type(): 'Community' | 'Standalone' {
if (COMMUNITY_CATEGORIES.includes(this.category)) {
return 'Community';
} else {
return 'Standalone';
}
}
}
Alright! We're free of type checking errors!
LET'S COMMIT!
One more thing about models before we move on. This model doesn't have any relationships on it, but if it did, we would use a similar strategy to what we did with attributes: the declare property modifier. The Ember Data types give us handy types that keep track of the many intricacies of Ember Data relationships. Cool!
import Model, {
AsyncBelongsTo,
AsyncHasMany,
belongsTo,
hasMany,
} from '@ember-data/model';
import Comment from 'my-app/models/comment';
import User from 'my-app/models/user';
export default class PostModel extends Model {
@belongsTo('user') declare author: AsyncBelongsTo<User>;
@hasMany('comments') declare comments: AsyncHasMany<Comment>;
}
Routes
The next leaf in includes routes. Let's convert the index route. It's pretty simple, with a model hook that accesses the Ember Data store and finds all of the rentals:
// app/routes/index.js
import Route from '@ember/routing/route';
import { inject as service } from '@ember/service';
export default class IndexRoute extends Route {
@service store;
model() {
return this.store.findAll('rental');
}
}
First, we'll rename the file to TypeScript...and once again we have some type-checking errors:
// app/routes/index.ts
import Route from '@ember/routing/route';
import { inject as service } from '@ember/service';
export default class IndexRoute extends Route {
// Member 'store' implicitly has an 'any' type.
@service store;
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
model() {
return this.store.findAll('rental');
}
}
The first error is Member 'store' implicitly has an 'any' type. We know that the type of the store service is a Store. We can import the Store type from '@ember-data/store' and add the type annotation.
@service store: Store;
And because the store is set by the @service decorator, we need to use the declare property modifier again.
@service declare store: Store;
And the last type-checking error is again the linter telling us we need a return type on the function. Here's a little hack you can use to check the return type. Pop void in as the return type. In this case, we get a type-checking error, as expected because we know the model hook does not actually return void :
// app/routes/index.ts
import Route from '@ember/routing/route';
import { inject as service } from '@ember/service';
import Store from '@ember-data/store';
export default class IndexRoute extends Route {
@service store: Store;
// Type 'PromiseArray<any>' is not assignable to type 'void'.
model(): void {
return this.store.findAll('rental');
}
}
Hmm... PromiseArray makes sense, but I wouldn't expect an array of any values. It should be a more specific type. Something seems wrong here.
We've run into one of the first gotchas of using TypeScript with Ember. Ember makes heavy use of string key lookups. For example, here we look up all of the rentals by passing the 'rental' string to the Store's findAll method. In order for TypeScript to know that the 'rental' string correlates with the RentalModel, we need to add some boilerplate to the end of the rental model file. The ember-cli-typescript installation added a ModelRegistry for this purpose, and we just need to register our RentalModel with the registry:
// app/models/rental.ts
export default class RentalModel extends Model {
// ...
}
declare module 'ember-data/types/registries/model' {
export default interface ModelRegistry {
rental: RentalModel;
}
}
And now, we get a much more useful error!
// app/routes/index.ts
import Route from '@ember/routing/route';
import { inject as service } from '@ember/service';
import Store from '@ember-data/store';
export default class IndexRoute extends Route {
@service store: Store;
// Type 'PromiseArray<RentalModel>' is not assignable to type 'void'.
model(): void {
return this.store.findAll('rental');
}
}
It looks like our return type is a Promise Array of Rental Models. We can add the appropriate imports and the type annotation, and now we have no more type-checking errors!
import Route from '@ember/routing/route';
import { inject as service } from '@ember/service';
import Store from '@ember-data/store';
import DS from 'ember-data';
import RentalModel from 'super-rentals/models/rental';
export default class IndexRoute extends Route {
@service declare store: Store;
model(): DS.PromiseArray<RentalModel> {
return this.store.findAll('rental');
}
}
(NOTE: We have to use DS.PromiseArray because PromiseArray is private so the type isn't exported. 🤷♀️)
LET'S COMMIT!
See also: Converting the Rental Route.
Components
Next, let's try converting a component, the inner-most leaf of our app.
The Rentals::Filter component filters the list of vacation rentals based on a passed-in search query.
Typed Ember extends Confidence Part 2: Converting Your Ember App to TypeScript
When we rename the file, we see some type-checking errors:
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
export default class RentalsFilterComponent extends Component {
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get results() {
// Property 'rentals' does not exist on type '{}'.
// Property 'query' does not exist on type '{}'.
let { rentals, query } = this.args;
if (query) {
// Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
The first type-checking error is the linter reminding us to add a return type to the function. From reading the code, it looks like we are expecting this function to return an array of Rental models, so let's put that for now:
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
export default class RentalsFilterComponent extends Component {
get results(): Array<RentalModel> {
// Property 'rentals' does not exist on type '{}'.
// Property 'query' does not exist on type '{}'.
let { rentals, query } = this.args;
if (query) {
// Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
Alright! Next type-checking error:
Property 'rentals' does not exist on type '{}'.
We are destructuring the component args, but it looks like TypeScript has no idea what properties the args object should have. We have to tell TypeScript what the component arguments are.
Fortunately, the Glimmer Component type is a generic. It takes an optional type argument where you can specify your args. First, we'll define an interface called RentalsFilterArgs. We'll mark the types for the arguments as unknown for now. Then, we can pass that interface as an argument to the Component type: Component<RentalsFilterArgs>.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
interface RentalsFilterArgs {
rentals: unknown;
query: unknown;
}
export default class RentalsFilterComponent extends Component<RentalsFilterArgs> {
get results(): Array<RentalModel> {
let { rentals, query } = this.args;
if (query) {
// rentals: Object is of type 'unknown'.
// rental: Parameter 'rental' implicitly has an 'any' type.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
// Type 'unknown' is not assignable to type 'RentalModel[]'.
return rentals;
}
}
Now, TypeScript knows about our component's arguments, but it's complaining that because the rentals type is unknown, TypeScript doesn't know what to do with the filter method. Let's resolve these by adding a type to the rentals argument.
By doing a little sleuthing, tracing the component invocations back to the route template, we discover that the rentals argument is the resolved model from the IndexRoute.
<!-- app/components/rentals.hbs -->
<!-- ... -->
<!-- @rentals is passed into Rentals::Filter in the Rentals component -->
<Rentals::Filter @rentals={{@rentals}} @query={{this.query}} as |results|>
<!-- ... -->
</Rentals::Filter>
<!-- app/templates/index.hbs -->
<!-- ... -->
<!-- @rentals is passed into the Rentals component in the Index Route -->
<Rentals @rentals={{@model}} />
We can extract the model type from the Index Route by using the ModelFrom utility type borrowed from the ember-cli-typescript documentation cookbook.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
import IndexRoute from 'super-rentals/routes';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsFilterArgs {
rentals: ModelFrom<IndexRoute>;
query: unknown;
}
export default class RentalsFilterComponent extends Component<RentalsFilterArgs> {
get results(): Array<RentalModel> {
let { rentals, query } = this.args;
if (query) {
// Type 'RentalModel[]' is missing the following properties from type
// 'ArrayProxy<RentalModel>': content, objectAtContent, _super, init, and
// 5 more.
// Argument of type 'unknown' is not assignable to parameter of type 'string'.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
// Type 'ArrayProxy<RentalModel>' is missing the following properties from
// type 'RentalModel[]': pop, push, concat, join, and 19 more.
return rentals;
}
}
Updating the rentals type in the arguments interface resolves not only the type-checking error that we've been working on, but also another one further down in the code. Sweet!
By extracting the type rather than just hard-coding it to what we think it will be, we can avoid two issues:
1. Our assumption might not be correct, and because TypeScript isn't checking our templates, it won't know. This bug in our types could potentially proliferate throughout our app and cause problems when we ship our code.
2. The resolved model's type might change. If we've hard-coded the type in our arguments interface, TypeScript won't be able to help us find all of the places where we are using the model's value to update them to match the change.
What it boils down to is: we always want our answer key to have accurate and up-to-date answers so that we can trust it.
Unfortunately, we have some new type-checking errors. These errors are telling us that the rentals argument returns an ArrayProxy<RentalModel> but filter is coercing it into an Array<RentalModel>, which has slightly different behavior. For example, ArrayProxy doesn't have push or pop methods like an Array does. This could cause a bug in the future! 🐛 We always want to return an Array, so we can resolve this by first converting the rentals argument to an Array before using it.
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalModel from 'super-rentals/models/rental';
import IndexRoute from 'super-rentals/routes';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsFilterArgs {
rentals: ModelFrom<IndexRoute>;
query: unknown;
}
export default class RentalsFilterComponent extends Component<RentalsFilterArgs> {
get results(): Array<RentalModel> {
let { query } = this.args;
let rentals = this.args.rentals.toArray();
if (query) {
// Argument of type 'unknown' is not assignable to parameter of type 'string'.
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
OK, we're down to one final type-checking error:
Argument of type 'unknown' is not assignable to parameter of type 'string'.
TypeScript is telling us that the includes method on the rental.title string expects a string to be passed to it, but we've passed an unknown. Let's find out what that query argument type actually is!
Just like with rentals, we want to extract the type from the calling component if possible. In this case, query is a tracked property on that component. We can get the type of that property by importing the RentalsComponent type and looking-up the type of the query property using a similar syntax to what we'd use to access a value on an object. (👋👋 NOTE: For TypeScript to compile, you'll also need to convert the Rentals component to TypeScript if you are following along.)
// app/components/rentals/filter.ts
import Component from '@glimmer/component';
import RentalsComponent from 'super-rentals/components/rentals';
import RentalModel from 'super-rentals/models/rental';
import IndexRoute from 'super-rentals/routes';
import { ModelFrom } from 'super-rentals/types/util';
interface RentalsFilterArgs {
rentals: ModelFrom<IndexRoute>;
query: RentalsComponent['query'];
}
export default class RentalsFilterComponent extends Component<RentalsFilterArgs> {
get results(): Array<RentalModel> {
let { query } = this.args;
let rentals = this.args.rentals.toArray();
if (query) {
rentals = rentals.filter((rental) => rental.title.includes(query));
}
return rentals;
}
}
Phew! We're done!
LET'S COMMIT!
Let's take a look at one more component. The Map component, which displays a map of the given coordinates. First, we'll rename the file to TypeScript and take a look at the resulting type-checking errors:
// app/components/map.ts
import Component from '@glimmer/component';
import ENV from 'super-rentals/config/environment';
const MAPBOX_API = '<https://api.mapbox.com/styles/v1/mapbox/streets-v11/static>';
export default class MapComponent extends Component {
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get src() {
// Property 'lng' does not exist on type '{}'.
// Property 'lat' does not exist on type '{}'.
// Property 'width' does not exist on type '{}'.
// Property 'height' does not exist on type '{}'.
// Property 'zoom' does not exist on type '{}'.
let { lng, lat, width, height, zoom } = this.args;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
// Missing return type on function.
// eslint(@typescript-eslint/explicit-module-boundary-types)
get token() {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
Let's start by adding our arguments interface and resolving the return-type lints..
import Component from '@glimmer/component';
import ENV from 'super-rentals/config/environment';
const MAPBOX_API = '<https://api.mapbox.com/styles/v1/mapbox/streets-v11/static>';
interface MapArgs {
lng: unknown;
lat: unknown;
width: unknown;
height: unknown;
zoom: unknown;
}
export default class MapComponent extends Component<MapArgs> {
get src(): string {
let { lng, lat, width, height, zoom } = this.args;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
get token(): string {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
Look at that! All of our type-checking errors went away! For your first pass converting your app, I think it's totally fine to merge the unknown types like this. (It's way better than merging any.)
LET'S COMMIT!
But I have a few more things I want to show you, so we'll add the real types now.
In this case, we expect this component to be re-used all over our app, so we don't want to extract the argument types from the caller like we did for the Rentals::Filter component. Instead, we'll hard-code the types in the interface by reverse-engineering the types from one of the invocations:
<!-- example invocation -->
<Map
@lat={{@rental.location.lat}}
@lng={{@rental.location.lng}}
@zoom="9"
@width="150"
@height="150"
alt="A map of {{@rental.title}}"
/>
// app/components/map.ts
import Component from '@glimmer/component';
import ENV from 'super-rentals/config/environment';
const MAPBOX_API = '<https://api.mapbox.com/styles/v1/mapbox/streets-v11/static>';
interface MapArgs {
lng: number;
lat: number;
width: string;
height: string;
zoom: string;
}
export default class MapComponent extends Component<MapArgs> {
get src(): string {
let { lng, lat, width, height, zoom } = this.args;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
get token(): string {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
With the actual types, we still don't have any type-checking errors. All good!
LET'S COMMIT!
But I wonder if there is anything we can do to make this component easier to reuse. For example, is there a way to throw an error any time an engineer forgets to pass in one of these arguments?
It turns out, there is. We can use a union type to tell TypeScript that the longitude and latitude arguments might be undefined. Then, we can use getters to alias the arguments, but with an added check using Ember debug's assert. The assertion will throw an error with the provided message if the condition is false. Also, the type for assert is written such that TypeScript now knows that the condition must be true for all of the following lines. This allows us to drop the undefined type from the argument before returning it as a number. Thus, we can use this.lng and this.lat elsewhere in our code without having to worry about the possibility of them being undefined. Also! The best part is that the assert code and its condition are stripped from your production builds, so you haven't added any production overhead. Sweet!
// app/components/map.ts
import { assert } from '@ember/debug';
import Component from '@glimmer/component';
import ENV from 'super-entals/config/environment';
const MAPBOX_API = '<https://api.mapbox.com/styles/v1/mapbox/streets-v11/static>';
interface MapArgs {
lng: number | undefined;
lat: number | undefined;
width: string;
height: string;
zoom: string;
}
export default class MapComponent extends Component<MapArgs> {
get lng(): number {
assert('Please provide `lng` arg', this.args.lng);
return this.args.lng;
}
get lat(): number {
assert('Please provide `lat` arg', this.args.lat);
return this.args.lat;
}
get src(): string {
let { width, height, zoom } = this.args;
let { lng, lat } = this;
let coordinates = `${lng},${lat},${zoom}`;
let dimensions = `${width}x${height}`;
let accessToken = `access_token=${this.token}`;
return `${MAPBOX_API}/${coordinates}/${dimensions}@2x?${accessToken}`;
}
get token(): string {
return encodeURIComponent(ENV.MAPBOX_ACCESS_TOKEN);
}
}
LET'S COMMIT!
See also: Converting the Rental::Image component to TypeScript.
See also: Converting the Rentals component to TypeScript.
See also: Converting the ShareButton component to TypeScript.
Alright! We're done converting our app!
Advanced Ember TypeScript Tidbits
Deeply Nested Gets
Very occasionally, you still need to use get (for proxies), even with Ember Octane. If your get call is accessing a deeply nested property, however, you will need to chain your get calls together. This is because TypeScript doesn't know to split the string lookup on dots. In practice, I haven't found that this comes up super often, and often, you don't actually need get for the entire chain.
// This gives you a confusing type-checking error:
myEmberObject.get('deeply.nested.thing');
// Do one of these instead:
myEmberObject.get('deeply').get('nested').get('thing');
myEmberObject.deeply?.nested?.get('thing');
myEmberObject.deeply?.get('nested').thing;
Ember Concurrency
Picture a simple Ember Concurrency task. When you perform the waitASecond task, it waits for a second, then logs 'done' to the console.
// my-app/components/waiter.js
import { action } from '@ember/object';
import Component from '@glimmer/component';
import { task, timeout } from 'ember-concurrency';
export default class Waiter extends Component {
@task *waitASecond() {
yield timeout(1000);
console.log('done');
}
@action startWaiting() {
this.waitASecond.perform();
}
}
Unfortunately, TypeScript doesn't know much about what the generator is doing to the waitASecond generator function, so it doesn't know that waitASecond is actually a Task that you can call perform on. To use Ember Concurrency with TypeScript, we need to use an add-on called ember-concurrency-ts, which gives us a taskFor method that casts the TaskGenerator as a Task:
// my-app/components/waiter.ts
import { action } from '@ember/object';
import Component from '@glimmer/component';
import { task, timeout, TaskGenerator } from 'ember-concurrency';
import { taskFor } from 'ember-concurrency-ts';
export default class Waiter extends Component {
@task *waitASecond(): TaskGenerator<void> {
yield timeout(1000);
console.log('done');
}
@action startWaiting(): void {
taskFor(this.waitASecond).perform();
}
}
Typed Templates
You can try typed templates using the els-addon-typed-templates add-on in conjunction with the Unstable Ember Language Server and/or ember-template-lint-typed-templates. It's a pretty neat little add-on that will type-check your templates, including component invocations. Admittedly, it feels like a work-in-progress, but we did find several bugs in our app when we turned it on.
One important gotcha we've found with this add-on is that when you change something in a TypeScript file, you need to "tickle" the relevant template file (e.g. by adding then removing a line) to get the add-on to re-check it.
Alternatively, you can try Glint, a new typed-template solution by members of the ember-cli-typescript team. I haven't tried it yet, but I'm sure it's awesome!
Mirage Types
One of the biggest sticking points we had with TypeScript conversion was converting test files that use Mirage.
MirageJS, which powers ember-cli-mirage, does have types, but we ran into issues using them with ember-cli-mirage without lots of really complicated gymnastics that won't fit in this blog post. To that end, I am posting a GitHub gist with our gymnastics, which will hopefully be helpful to you. (NOTE: If you are a TypeScript beginner, it's OK to be overwhelmed reading the types in that gist. It was certainly overwhelming writing them! ❤️)
TypeScript Without TypeScript
No appetite for switching? You can get some of TypeScript's benefits—such as code completion and documentation-on-hover—by using JSDoc documentation in your JavaScript along with the VSCode text editor. JSDoc allows you to document types, though it doesn't have all of TypeScript's features.
VSCode's JavaScript features are powered by the TypeScript compiler under the hood, so you even get access to TypeScript's built-in types. You can also add @types packages from Definitely Typed, and VSCode will use those types as well.
Once you've documented the types in your JavaScript files, you can even add a @ts-check comment to the top of your file to get type checking in your JavaScript files, powered by TypeScript!
Moving on
In the next article, we'll talk about the benefits of TypeScript in the context of developer confidence.
]]>
<![CDATA[Typed Ember extends Confidence Part 1: What is TypeScript?]]>https://blog.skylight.io/ts-extends-confidence-1/605cf7c5f63ddf003bd1db1eTue, 30 Mar 2021 15:00:00 GMT
This article is part 1 of a series on converting your Ember app to TypeScript to foster confidence in your engineering team, based on my talk for EmberConf 2021.
We're going to start with some basics: "What even is a type? What is TypeScript?" Then, we'll look at what TypeScript looks like in an Ember app before circling back to the benefits of TypeScript in the context of developer confidence.
What is a Type?
You've likely come across the concept of "types" before. A value's type tells us what kind of data it stores and what you can and cannot do with that data.
JavaScript Primitive Types
The most basic types are called primitives. You can check a value's primitive type by using typeof, with the exception of null (👋👋 We'll come back to this later). Let's take a look at JavaScript's primitive types:
A number can hold a floating-point number (but shouldn't be used for numbers that exceed Number.MAX_SAFE_INTEGER), Infinity, or NaN (not a number).
typeof 1;
//=> 'number'
typeof 1.0;
//=> 'number'
Number.MAX_SAFE_INTEGER;
//=> 9007199254740991
1 / 0;
//=> Infinity
typeof Infinity;
//=> 'number'
typeof NaN;
//=> 'number'
For those values exceeding Number.MAX_SAFE_INTEGER, "bigint" to the rescue! A bigint can hold integers of arbitrary size (up to a limit determined by the JavaScript implementation).
typeof 9007199254740991n;
//=> 'bigint'
typeof (9007199254740991n ** 9007199254740991n);
//=> Uncaught RangeError: Maximum BigInt size exceeded
A string can hold a sequence of characters to represent text.
typeof 'Hello, EmberConf!';
//=> 'string'
typeof '';
//=> 'string'
A boolean can hold either true or false.
typeof true;
//=> 'boolean'
typeof false;
//=> 'boolean'
A symbol is a unique, anonymous value (👋 handwave, 👋 handwave, don't worry too much about this one). (If you know Ruby, this is not the same as Ruby symbols.)
typeof Symbol();
//=> 'symbol'
The undefined value is assigned to variables that have been declared but not yet defined.
typeof undefined;
//=> 'undefined'
let myVariable;
typeof myVariable;
//=> 'undefined'
let myObject = { hello: 'EmberConf!' }
typeof myObject.goodbye;
//=> 'undefined'
And finally, null is a value you can assign to a variable to indicate intentional absence.
typeof null;
//=> 'object'
null === null;
//=> true
As we can see above, typeof null returns... 'object'? We've run across the first gotcha in using typeof to check a type. It turns out that typeof null returns 'object' due to how null was implemented in the very first implementation of JavaScript. Unfortunately, changing this breaks the internet, so we're stuck with it. Because there is only one null value, you can just check if null === null.
In JavaScript, primitives are immutable values that are not objects and have no methods. This might sound confusing, because we know that we can create a string and then call methods on it. For example:
let s = 'Hello, EmberConf!';
s.startsWith('Hello');
//=> true
These methods are available because—with the exception of undefined and null—the JavaScript implementation will wrap all primitives in their respective wrapper objects to provide methods. In the example above, we can imagine the following happening under the hood:
// What we type
let s = 'Hello, EmberConf!';
// What the JavaScript implementation does under the hood
let s = new String('Hello, EmberConf!');
//=> String {
// 0: 'H',
// 1: 'e',
// 2: 'l',
// 3: 'l',
// 4: 'o',
// ...
// 16: '!',
// length: 17,
// __proto__: String, <= this is where the methods come from
// }
JavaScript Structural Types
In addition to primitives, JavaScript has more complex structural types:
An object is a mutable collection of properties organized in key-value pairs. Arrays, sets, maps, and other class instances are all objects under the hood. Because typeof will return the string 'object' regardless of the class, instanceof and other checks are more useful here. (👋👋 NOTE: For framework code or when using iFrames, you might not want to use instanceof either.)
typeof { hello: 'EmberConf!' };
//=> 'object'
typeof ['Hello', 'EmberConf!'];
//=> 'object'
typeof new Set(['Hello', 'EmberConf!']);
//=> 'object'
typeof new Map([['Hello', 'EmberConf!']]);
//=> 'object'
['Hello', 'EmberConf!'] instanceof Array;
//=> true
// preferred
Array.isArray(['Hello', 'EmberConf!']);
//=> true
new Set(['Hello', 'EmberConf!']) instanceof Set;
//=> true
new Map([['Hello', 'EmberConf!']]) instanceof Map;
//=> true
The other structural type is function. A function is a callable object.
function hello(conf = 'EmberConf') { return `Hello, ${conf}!` }
typeof hello;
//=> 'function'
hello();
//=> 'Hello, EmberConf!'
// This is what "callable" means:
hello.call(this, 'RailsConf');
//=> 'Hello, RailsConf!'
// But it's still just an object:
hello.hola = 'Hola!';
hello.hola;
'Hola!'
JavaScript is a loosely typed and dynamic language.
You may have heard that JavaScript is a loosely typed and dynamic language. What does this mean?
In JavaScript, loosely typed means that every variable has a type, but you can't guarantee that the type will stay the same. For example, you can change the type of a variable by assigning a different value to it:
let year = 2021;
typeof year;
//=> 'number'
year = 'two thousand and twenty one';
typeof year;
//=> 'string';
Even stranger, in some instances, JavaScript will implicitly coerce your value to a different type, sometimes in unexpected ways.
2 + 2;
//=> 4
2 + '2';
//=> '22'
2 + [2];
//=> '22'
2 + new Set([2]);
//=> '2[object Set]'
2 + true;
//=> 3
2 + null;
//=> 2
2 + undefined;
//=> NaN
JavaScript is also a dynamically typed language. This means that you never need to specify the type of your variable. Instead, the JavaScript implementation determines the type at run-time, and it will do the best it can with that knowledge at run-time. Sometimes, that means coercion, as we just saw. And sometimes you get...dun dun dun...the dreaded Type Error.
var undef;
undef.eek;
// 💣 TypeError: 'undefined' is not an object
This is fine
Great...so now we know that every variable in JavaScript has a type. We also know that the type of the variable can be changed and that if we use a value improperly, JavaScript will either implicitly coerce it with unexpected results or throw an error.
What could go wrong?
Typed Ember extends Confidence Part 1: What is TypeScript?
It turns out, quite a bit. In 2018, the error monitoring company Rollbar analyzed their database of JavaScript errors and found that 8 of the top 10 errors were some variation of trying to read or write to an undefined or null value.
Furthermore, because of type coercion, it's possible you might have additional type-related bugs that don't cause errors to be thrown in your app.
All of this leads to uncertainty. And uncertainty is the enemy of confidence.
What is TypeScript?
Fortunately, TypeScript can help!
TypeScript is an extension of JavaScript. When writing TypeScript, you can use all of JavaScript's features, plus additional TypeScript features.
Typed Ember extends Confidence Part 1: What is TypeScript?
The main difference, syntactically, is that TypeScript adds optional type annotations on top of the JavaScript you already know and love. When the compiler turns your TypeScript into JavaScript, it determines the types of the values in your code and checks the validity of the types in the contexts in which you use them before outputting standard JavaScript (with the type information removed). If you've used a value incorrectly, you get a type-checking error, alerting you to the issue before you ship your code.
Typed Ember extends Confidence Part 1: What is TypeScript?
Also, because our text editor can run the TypeScript compiler in the background, it can integrate the type information and other related documentation into the editor user experience. For example: code completion, hover info, and error messages. VSCode gives you these features out of the box, no installation required.
And because TypeScript comes with all of JavaScript's built-in types baked in, such as DOM types, you have a ton of information at your fingertips.
It's basically like having an answer key to your code. Having an answer key available to you at all times not only reduces your cognitive overhead, but it makes you feel like a rock star.
Typed Ember extends Confidence Part 1: What is TypeScript?
So…how does TypeScript get the answer key?
Because TypeScript is a strictly and statically typed language.
Statically Typed*
(*but also dynamically typed because it compiles to JavaScript!)
Statically typed means that TypeScript checks your code for potential type errors at compile-time. If the TypeScript compiler determines that you have a potential Type Error, it will log a "type-checking error" during compilation. Fix it and no runtime error.
let myVariable = 1;
// Type 'string' is not assignable to type 'number'.
myVariable = 'string cheese';
For all of this magic to work, TypeScript needs to know the type of your values at compile-time. Unlike some other strictly typed languages, TypeScript can sometimes infer the type of a value from its usage. Other times, you may need or prefer to declare the type of a value with a type annotation.
let myVariable: Array<number> = [];
myVariable.push(1);
// Argument of type 'string' is not assignable to parameter of type 'number'.
myVariable.push('string cheese');
It's worth noting that unlike some other statically typed languages, TypeScript will still compile even when you have type-checking errors. There are a couple of implications to this:
1. Should a Type Error make it through type-checking, the compiled JavaScript code will still throw the error at run-time.
2. If you are converting JavaScript code to TypeScript and you have type errors because your types aren't exactly right yet, you can still go into the console to poke around. I find this strategy super useful to avoid feelings of "fighting the type system" that you might get from other statically typed languages.
In other statically typed languages, the type system can feel like a gatekeeper. In TypeScript, it feels more like a messenger. While type-checking errors can be frustrating at times, they're almost always telling you useful information. "Don't shoot the messenger."
Strict, but not TOO strict
Typescript is more strictly typed than JavaScript.
Once a value has a type, TypeScript will not allow you to change that type (with the exception of undefined and null).
Also, TypeScript disallows a lot of implicit type coercion. For example, you can add the number 2 to the number 2, but you will get type-checking errors if you try to add, for example, an array or a set to the number 2.
2 + 2;
//=> 4
// Operator '+' cannot be applied to types 'number' and 'number[]'.
2 + [2];
//=> '22'
// Operator '+' cannot be applied to types 'number' and 'Set<number>'.
2 + new Set([2]);
//=> '2[object Set]'
// Operator '+' cannot be applied to types 'number' and 'boolean'.
2 + true;
//=> 3
// Object is possibly 'null'.
2 + null;
//=> 2
// Object is possibly 'undefined'.
2 + undefined;
//=> NaN
Interestingly, TypeScript will still allow you to add a string to a number. The compiled JavaScript will implicitly convert the number to a string before concatenating the two strings. In my example, this might seem ridiculous:
2 + '2';
//=> '22'
Though you might be able to imagine it happening in the case of, say, an input value:
2 + document.querySelector('input[type="number"]').value;
//=> '22'
But in the real world, adding a number to a string is a common-enough thing to do intentionally that it's considered idiomatic (This just means "everyone does it"). For example:
let itemCount = 42;
throw 'Too many items in queue! Item count: ' + itemCount;
//=> Error: Too many items in queue! Item count: 42
The TypeScript team decided not to make TypeScript too strict in this case. If you disagree with them, you can enable an ESLint rule to forbid this:
// Operands of '+' operation must either be both strings or both numbers.
// Consider using a template literal.
// eslint(@typescript-eslint/restrict-plus-operands)
2 + '2';
//=> '22'
This is one example of how TypeScript's strictness is configurable. You can increase or decrease the strictness via a file called tsconfig.json. Enabling "strict": true puts you in the strictest mode. And if that's not strict enough for you, you can enable even more checks with the typescript-eslint plugin.
Type Safety
Strictness helps you achieve something called type safety. This means that TypeScript will help you avoid those pesky Type Errors. In fact, in a 2017 paper for the Institute of Electrical and Electronics Engineers convention, researchers found that TypeScript detected 15% of public bugs.
Type safety helps you become a more confident developer.
TypeScript Types
As I mentioned before, the main difference between TypeScript syntax and JavaScript syntax is type annotations. Let's start by revisiting JavaScript's basic types in TypeScript syntax.
Primitive Types
For example, here are examples of explicit type declarations for each of JavaScript's primitives represented in TypeScript.
let myVariable: number = 1;
let myVariable: bigint = 9007199254740991n;
let myVariable: string = 'Hello, EmberConf!';
let myVariable: boolean = true;
let myVariable: symbol = Symbol();
let myVariable: undefined;
let myVariable: null = null;
Of course, as I mentioned before, TypeScript can infer the type of your value from it's usage, so these explicit annotations may not always be necessary:
let myVariable = 1;
let myVariable = 9007199254740991n;
let myVariable = 'Hello, EmberConf!';
let myVariable = true;
let myVariable = Symbol();
let myVariable;
let myVariable = null;
Structural Types
The annotations for structural types start to get a little more complicated. Here are examples of explicit type declarations for different structural types:
The Array type is an example of a generic type—a reusable type that takes another type as an argument (denoted with angle brackets). In this case, the Array type takes string as an argument, and TypeScript now knows that our variable is an array of strings. (👋👋 NOTE: You can also use the string[] notation for an array.)
let myVariable: Array<string> = ['Hello', 'EmberConf!'];
To declare the type of a function, declare the type of each variable and the return type, as so:
function sayHello(crowd: string): string {
return `Hello, ${crowd}!`;
}
sayHello('EmberConf');
//=> 'Hello, EmberConf!'
// Argument of type 'number' is not assignable to parameter of type 'string'.
sayHello(1);
//=> 'Hello, 1!'
For an object, use an interface to represent each of the properties and their types:
interface MyObject {
hello: string;
}
let myVariable: MyObject = { hello: 'EmberConf!' };
// Property 'goodbye' does not exist on type 'MyObject'.
myVariable.goodbye;
Moar Types!
In addition to JavaScript's basic types, TypeScript provides additional types. Let's go over a few types you might need to understand the next article in this series:
The unknown type is useful for when you don't know the type of the value. When you use unknown, you can "narrow" the type of the value using typeof or other comparisons.
function prettyPrint(raw: unknown): string {
if (typeof raw === 'string') {
// TypeScript now knows that `raw` is a string
return raw;
}
if (Array.isArray(raw)) {
// TypeScript now knows that `raw` is an array
return raw.join(', ');
}
throw '`prettyPrint` not implemented for this type';
}
The any type can also be used when you don't know the type of a value. The difference, though, is that when you annotate a value as any, TypeScript will allow you to do anything with it. Essentially, when you use the any type, you are opting out of static type checking for that variable. Proceed with caution! (Fortunately there are tsconfig and eslint-typescript rules to forbid using any!)
let yolo: any = 'hehehe';
// TypeScript won't yell at you here
yolo = null;
// or here
yolo.meaningOfLife;
//=> TypeError: Cannot read property 'meaningOfLife' of null
And lastly, the void type is the absence of a type. The void type is most commonly used to specify that we don’t expect this function to return anything:
function sayHello(crowd: string): void {
console.log(`Hello, ${crowd}!`);
}
function sayHello(crowd: string): void {
// Type 'string' is not assignable to type 'void'.
return `Hello, ${crowd}!`;
}
Moving On!
This concludes our TypeScript overview. Now, let's move on to the fun stuff: converting an Ember app to TypeScript!
]]>
<![CDATA[Skylight 5: Now with Source Locations!]]>https://blog.skylight.io/skylight-5-source-locations/60491446d2bb990039d7fa16Fri, 12 Mar 2021 18:27:08 GMT
This week we released Skylight version 5.0, which represents a major undertaking that has involved every person at Tilde and every part of our ever-growing stack. In addition to major internal refactors, this release also modernizes our native Rust code, and introduces Skylight's newest feature, Source Locations.
Source Locations
Starting now, Skylight can help you pinpoint the locations in your code that correspond to events in the event sequence. As Skylight traces your code, it will report the file names (with line numbers) or gem names that most likely triggered the event. No more scouring your code trying to find out exactly where an expensive SQL query originated! As you browse your endpoint data, you will find these source locations in the detail card for each event:
Skylight 5: Now with Source Locations!
If your app is synced with Github, we will also provide links to go directly to that line for the specified commit.
You can read more about Source Locations on our support page, and as always, please try it out and let us know what you think! Your feedback is invaluable as we continue to improve this and other Skylight features.
Module#prepend
Skylight 5 also includes a shift to Module#prepend for adding instrumentation to Rails or other third-party code that does not already have it. In versions 4 and below, most instrumentation was added via alias method chaining. Module#prepend is now the preferred way of overriding an existing method, but it comes with a caveat: if multiple libraries attempt to patch the same method, they should either all use Module#prepend or alias method chaining; mixing the two strategies can often result in unintended recursion. We will continue to support Skylight 4 for the immediate future to help ease the transition in case your code isn't prepend-ready, but otherwise recommend upgrading as soon as possible.
The Future
The Source Locations feature is just the tip of an iceberg-in-progress: to implement it, the Skylight team has invested considerable engineering efforts into a new backend framework, written in Rust, which will allow us to easily deploy purpose-built services for new features like this one. Stay tuned for future announcements!
]]>
<![CDATA[May 15 Outage Post-Mortem]]>https://blog.skylight.io/may-15-outage-postmoterm/5ebf22a30417a10045162339Fri, 15 May 2020 23:34:27 GMTLast night, we had an incident in our data-processing pipeline that resulted in some data loss.
At around 11:30 PM Pacific Time, an on-call engineering was paged due to a server becoming unresponsive and unreachable. While quite rare, our infrastructure is robust enough to tolerate some servers going down and it does not usually cause any service disruption.
Unfortunately, the situation was a bit different this time. Shortly after the first page, another server started exhibiting the same symptoms. Eventually, all our servers were affected by the outage.
Eventually, we managed to stabilize the system. The servers were up and running again, database availability was improving and began the process of automatic data repair and recovery. The web servers were accepting requests again, which means the Skylight agents could resume sending reports. However, the data-processing part of the system remained stuck in a restart loop due to a Kafka error.
Normally, Kafka is one the most robust parts of our system. Upon receiving reports from agents, after some lightweight authentication and validation steps, the contents of these agent reports were promptly written to Kafka while awaiting further processing. Because of Kafka's track record of being highly available, this split of responsibility in our architecture has historically prevented data loss during outages – as long as the data is in Kafka, we can always catch up on processing it after the issue is resolved.
This time, we were not so lucky. Because all of our servers went down together in short succession, it had defeated our redundancy and replication strategy. Not only was the Kafka cluster unavailable during the outage window, when the nodes eventually came back online, they suffered from a data consistency issue that caused a good amount of data to become unavailable. When the workers started back up, they tried to resume processing data from where they left off, and because the data was no longer available in Kafka, this caused a crash in the workers and thus they were stuck in a restart loop unable to make progress.
To be clear, Kafka wasn't used for storing persistent data. Once an agent report has been processed by a worker, the data in Kafka is no longer needed. However, it did mean that any reports that were submitted during the outage window that hadn't been processed were lost permanently. In other words, you may notice a gap of data missing on your Skylight dashboard from around Thursday May 14 11:30 PM Pacific Time and possibly up to around Friday May 15 3 AM or so.
Once we became certain that the data in Kafka was unrecoverable, we instructed the workers to skip over the agent reports in the affected window, so that they can start ingesting new data and unblock the processing of agent reports. We are very sorry about this, but given the circumstances at the time, we believe this was the right call.
Initially, we had assumed the incident was due to a widespread network partition event at the data center, as it seems to fit the reachability issues we observed at the time. Upon further investigation, it turned out that this was caused by a bad automatic security update, similar to another incident in the past. A bad package was pushed to Ubuntu's security channel yesterday. Under certain circumstances, installing this package will cause a kernel panic, which was what happened here.
Now that we have identified the root cause of the incident, we will work on mitigating the risk of it happening again in the future. In the short term, we plan to make some adjustments to our automatic security updates to allow for more time to discover and respond to issues like this. We also plan on looking into improving the redundancy of our Kafka cluster and potentially moving to a managed Kafka solution.
Once again, we are really sorry about this.
]]>
<![CDATA[The Lifecycle of a Response]]>https://blog.skylight.io/the-lifecycle-of-a-response/5eb04fb46776fb003934ffbfTue, 05 May 2020 17:59:51 GMT
This post is a write-up of the talk I gave at RailsConf 2020. You can find the slides here.
Last year, the Skylight team gave a talk called Inside Rails: The Lifecycle of a Request. In that talk, we covered everything that happens between typing a URL into your browser to a request reaching your Rails controller action. But that talk ended with a cliffhanger:
Once we are in the controller action, how does Rails send our response back to the browser?
Together, these two talks paint a complete picture of the browser request/response cycle, the foundation that the whole field of web development is built on. But don't worry, you don't need to have seen that talk to understand this one. We'll start with a little recap of the important concepts.
Buckle up, because we're headed on a safari into the lifecycle of the response.
The Lifecycle of a Response
First, a little recap...
Let's get in our Safari Jeep and head on over to "skylight.io/safari". When we visit this page, we should see "Hello World." Let's go!
The Lifecycle of a Response
Oh no!!!! It appears that our safari server has been overtaken by lions. Instead of "Hello World" we see... "Roar Savanna"?! How did this happen? Let's find out! First, we need to answer this question:
When our browser connects to a server, how does the server know what the browser is asking for?
The Lifecycle of a Response
The browser and the server have to agree on a language for "speaking" to each other so that each can understand what the other is asking for. This set of rules is called "HTTP." It stands for hyper text transfer protocol, which is the language that both browsers and web servers can understand. "Protocol" is just a fancy word for "set of rules."
To get "skylight.io/safari", here is the simplest request that we could make. It specifies that it is a GET request, for the path /safari, using the HTTP protocol version 1.1, and it is for the host "skylight.io":
GET /safari HTTP/1.1
Host: skylight.io
And the HTTP-compliant response from the server looks something like this:
HTTP/1.1 200 OK
Content-Type: text/plain
Content-Length: 12
Date: Thu, 25 Apr 2019 18:52:54 GMT
Roar Savanna
It specifies that the request was successful, gives a bunch of header information—like Content-Type, Content-Length, and Date—and finally, "Roar Savanna"—the response body.
But what happened in between sending this request and receiving the response?
The request is sent from the browser, through the interwebs, to our web server. (👋 handwave, 👋 handwave, check out last year's talk for more info.)
Then, another protocol kicks in. The "Rack protocol" is a set of rules for how to translate an HTTP-compliant request into a format that a Rack-compliant Ruby app (like Rails) can understand.
The web server (such as puma or unicorn) interprets the HTTP request and parses it into an environment hash, then calls your Rails app with this hash:
env = {
'REQUEST_METHOD' => 'GET',
'PATH_INFO' => '/safari',
'HTTP_HOST' => 'skylight.io',
# ...
}
MyRailsApp.call(env)
Rails receives the environment hash, passes it through a series of "middleware" and into your controller action. (👋 handwave, 👋 handwave, check out last year's talk for more info.)
In our controller, the lions have written something like this:
class SafariController < ApplicationController
def hello
# Get it? A savanna is a type of plain...
render plain: "Roar Savanna"
end
end
The Safari Controller has an action called hello that tells Rails to render a plaintext response that says "Roar Savanna."
Rails runs your controller code, passes it back through all of that middleware, then returns an array of three things: the status code, a hash of headers, and the response body. We'll call this the "Response Array."
env = {
'REQUEST_METHOD' => 'GET',
'PATH_INFO' => '/safari',
'HTTP_HOST' => 'skylight.io',
# ...
}
status, headers, body = MyRailsApp.call(env)
# The Response Array:
status # => 200
headers # => { 'Content-Type' => 'text/plain', 'Content-Length' => '12', ... }
body # => ['Roar Savanna']
The Rack-compliant web server receives this array, converts it into an HTTP-compliant plaintext response, and sends it on its merry way back to your browser. Roar Savanna!
HTTP/1.1 200 OK
Content-Type: text/plain
Content-Length: 12
Date: Thu, 25 Apr 2019 18:52:54 GMT
Roar Savanna
Easy peasy, right?
But how did Rails know what to put in this array? And how does the browser know what to do with this response?
Read on to find out!
The Status Code
The first item in the response array is the "status code." Simply put, the status code is a three digit number indicating if the request was successful, or not, and why.
Status codes are separated into 5 classes:
• 1xx Informational (These are pretty rare, so we won't go into more detail.)
• 2xx Success!!
• 3xx Redirection
• 4xx Client Error (for errors originating from the client that made the request)
• 5xx Server Error (for errors originating on the server)
Standardized status codes help clients make sense of the response, even if they can't read English (or whatever human language the response body is written in). This allows the browser, for example, to display the appropriate UI elements to the user or in development tools.
The Lifecycle of a Response
Status codes also tell the Google crawler what to do: pages responding with 200 OK status codes will be indexed, pages responding with 500 errors will be revisited later, and the crawler will follow redirection instructions from pages responding with 300-series status codes.
The Lifecycle of a Response
For these reasons, we want to be as precise as possible when choosing a status code.
(Pro-tip: you can learn a lot more about status codes by going to https://httpstatuses.com/.)
The simplest responses are the ones that require no response body. Even better, we can tell the browser not to even expect a response body by choosing the correct status code.
For example, let's say our Safari Controller has an eat_hippo action:
class SafariController < ApplicationController
def eat_hippo
consume_hippo if @current_user.lion?
head :no_content # 204
end
end
The action allows the current user to consume the hippo as long as they are a lion. Then it responds with a simple 204, which means "the server has successfully fulfilled the request and there is no additional content to send in the response body." In Safari speak, that's "the lion successfully ate the hippo and we can expect the hippo to have no body"....or something.
In Rails, the head method is shorthand for "respond only with this status, headers, and an empty body." The head method takes a symbol corresponding to a status, in this case :no_content for "204."
Redirects
Another common set of status codes is the 300 series: redirects.
For example, if we send a GET request to "skylight.io/find-hippo", the find_hippo action redirects us to the oasis_url because it's the dry season and the hippos have moved to find water.
The Lifecycle of a Response
The Rails redirect_to method responds with a 302 Found status by default and includes a Location "header" (more on headers below) with the URL to which the browser should redirect. This status tells the browser "the hippo resides temporarily at the oasis URL. Sometimes the hippo resides elsewhere, so always check this location first."
But let's say the hippo has moved to the oasis permanently, maybe because of global warming. In this case, we could pass a status to redirect_to:
The Lifecycle of a Response
The :moved_permanently symbol corresponds with a 301 status code. This says to the browser, "the hippo has moved permanently to the oasis, so whenever you are looking for the hippo, look in the oasis." The next time you try to visit the hippo at /find-hippo, your browser can automatically visit /oasis instead without having to make the extra request to /find-hippo.
Alternatively, we could add the following to our routes file:
The Lifecycle of a Response
Handling the redirect in the routes file allows us to remove the controller action altogether. The redirect helper in the router responds with a 301 as well.
Danger! There is one important thing to note about the redirect_to method. The controller continues to execute the code in the action even after you've called redirect_to. For example, take a look at this version of the find_hippo action:
The Lifecycle of a Response
Because we didn't return when we called redirect_to, we actually hit both the redirect and render, so Rails doesn't know which response to respond with (a 301 or a 200?). Rails will throw a Double Render Error.
The Lifecycle of a Response
And fixed. By moving the redirect into a before_action, we ensure that render doesn't also get called because we now skip our entire controller action.
Status codes are a very concise way of conveying important information to the browser, but often, we need to include additional instructions to the browser about how to handle our response. Enter, headers.
The Lifecycle of a Response
Headers
Headers are included in a hash as the second item in the response array that our Rails app returns to our web server.
Headers are simply additional information about the response. This information might provide directions for the browser, such as whether and for how long to cache the response. Or it might provide metadata to use in a JavaScript client app.
We already talked about the Location header, which is used by the browser to know where it should redirect to.
Some other common headers you might see in a Rails app include:
• The Content-Type response header tells the browser what the content type of the returned content actually is—for example, an image, an html document, or just plain unformatted text. The browser checks this in order to know how to display the response in the UI.
• The Content-Length header tells the browser the length in bytes of the response. For example, you might send a HEAD request to an endpoint. That endpoint can respond with head :ok and a Content-Length so you can see how many bytes its response would be (in order to generate a download percentage, for example) without having to wait for the entire body to download (thus negating the usefulness of a download percentage). This header is set automatically by the Rack::ContentLength middleware.
• The Set-Cookie header includes a semi-colon separated key-value string representing the cookies shared between the server and the browser. For example, Rails sets a cookie to track a user's requests across a session. Cookies in Rails are managed by a class called, no joke, the CookieJar.
These headers, and many more, are managed automatically by Rails. You can also set a header manually using response.headers like this:
response.headers['HEADER NAME'] = 'header value'
HTTP Caching
Headers can be used to give the browser directions about caching. "HTTP caching" is when your browser (or a proxy of the browser) stores an entire HTTP response. The next time you make a request to that endpoint, the response can be shown to you more quickly.
The Lifecycle of a Response
Caching behavior varies depending on the status code returned in the response, which is yet another reason that status codes are important.
The main header used to control caching behavior is, not surprisingly, called the Cache-Control header. Let's look at some examples.
(Pro-tip: You can turn on caching in development by running rails dev:cache.)
Hippos are pretty big and difficult to render, so maybe we should just render the hippo once, then cache it forever. The controller method http_cache_forever allows us to do this.
The Lifecycle of a Response
It sets the Cache-Control header's max-age directive to 3 billion, 155 million, 695 thousand and 200 seconds (or one century, which is basically forever in computer years). It also sets the private directive, which tells the browser and all browser proxies along the way that "This is a private hippo and she would prefer to be cached only by this user's browser and not by a shared cache."
The private directive means only the account owner should have access to the response. The browser can cache it, but a cache between your server and the client, such as a "content distribution network" (or CDN), should not. If we want to allow caching by shared caches, we can just pass public: true to http_cache_forever to tell browser proxies that we're OK with them caching the hippo response along the way to the browser.
The Lifecycle of a Response
For another example of indefinite caching, let's include a picture of our hippo in the template. When we visit the page and look at the image source, we notice that Rails didn't just serve up the image at /assets/hippo.png. Instead, it served the image at /assets/hippo-gobbledygook.png.
The Lifecycle of a Response
What is that about?
When the server serves our image, it sets the Cache-Control header to the equivalent of http_cache_forever. Browsers and browser proxies, like the CDN I mentioned before, will cache that hippo pic forever.
But what if we change the picture? How will our users access the most up-to-date hippo pix on the interwebs?!
The answer is "fingerprinting." The "gobbledygook" is actually the image's "fingerprint," and it's generated every time the Rails asset pipeline compiles the image based on the content of the image. If the image changes, the fingerprint linked in the html changes, and instead of showing the user the cached hippo pic, the browser will retrieve the new version of the image.
OK...back to response caching...
Was it really smart to cache the entire hippo forever? Hippos only live for about 40 years, and surely they change throughout their lives? Maybe we should only cache the hippo for an hour.
The Lifecycle of a Response
The expires_in controller method sets the Cache-Control header's max-age directive to the given amount of time. Now, our browser will reload the hippo if we visit the page again after an hour.
But how do we know the hippo won't change within that hour?
This is hard to guarantee. It sure would be nice if we could ask the server if the hippo has changed and only use the cache if the hippo has not changed.
Well, I have good news for you! This is the default behavior with no caching-specific code whatsoever!
The Lifecycle of a Response
Rails adds the must-revalidate directive to the Cache-Control header. This means that the browser should revalidate the cached response before displaying it to the user. Rails also sets the max-age directive to zero seconds, meaning that the cached response should immediately be considered stale. Together, these directives tell the browser to always revalidate the cached response before displaying it.
So how does this "revalidation" work?
The first time we visited the /find-hippo endpoint, Rails ran our code to create the response body, including doing all that work to find and render the hippo. Before Rails passes the body along to your server, a middleware called Rack::ETag "digests" the response body into a unique "entity tag", similar to the asset fingerprints we talked about before.
# a simplified Rack::ETag
module Rack
class ETag
def initialize(app)
@app = app
end
def call(env)
status, headers, body = @app.call(env)
if status == 200
digest = digest_body(body)
headers[Etag] = %(W/"#{digest}")
end
[status, headers, body]
end
private
#...
end
end
Rack::Etag then sets the ETag response header with this entity tag:
Cache-Control: max-age=0, private, must-revalidate
ETag: W/"48a7e47309e0ec54e32df3a272094025"
Our browser caches this response, including the headers. When we visit this page again, our browser notices that the cached response is stale (max-age=0) and that we've requested that it "revalidate." So, when our browser sends the GET request, it includes the entity tag associated with the cached response back to the server via the If-None-Match request header:
GET /find_hippo HTTP/1.1
Host: skylight.io
If-None-Match: W/"48a7e47309e0ec54e32df3a272094025"
The server again runs our code to create the response body—including doing all the work to find and render the hippo again—then passes the body along to Rack::ETag again. And again, Rack::ETag digests the response body into the unique entity tag and sets the Etag response header.
Now, the next middleware in the chain, Rack::ConditionalGet checks if the new ETag header matches the entity tag sent along by the If-None-Match request header:
# a simplified Rack::ConditionalGet
module Rack
class ConditionalGet
def initialize(app)
@app = app
end
def call(env)
status, headers, body = @app.call(env)
if status == 200 && etag_matches?
status = 304
body = []
end
[status, headers, body]
end
private
def etag_matches?
headers['ETag'] == env['HTTP_IF_NONE_MATCH']
end
end
end
If they match, Rack::ConditionalGet will replace the status with 304 Not Modified and discard the body. The browser doesn't need to wait to download the redundant body, and the 304 status tells the browser to just use the cached response instead.
If the new Etag does not match, the server just sends the full response along with the original status code. The browser will now render a fresh hippo.
It seems like the server is still doing a lot of work rendering an entire hippo just to generate and compare ETags. If we know that the only reason that the response body is changing is because the hippo herself is changing, surely there is a better way?
Enter, the stale? method.
The Lifecycle of a Response
Now, our action says to render the hippo only if she is stale. We still get the same caching headers as we did with the default action, but the Etag is different even though our response body is identical. What changed here?
The stale? method tells Rails not to bother rendering the entire response body to build the ETag. Instead, just check if the hippo herself has changed and build the ETag based on that. Under the hood, Rails just generates a string based on a combination of the model name, id, and updated_at (in this case, "hippo/1-20071224150000"), then runs that through the ETag digest algorithm. This saves the server all of the effort of rendering the entire body to generate the ETag.
And finally, what if the hippo is so private that she never ever wants to be cached? Weirdly, Rails doesn't yet have a built-in method to do this, so you have to set the Cache-Control header directly.
The Lifecycle of a Response
The no-store directive says that the response may not be stored in any cache, be it the browser or any proxies along the way. This is not to be confused with the poorly-named no-cache directive, which despite its name means that the response can be stored in any cache, but the stored response must be revalidated every time before it can be used.
Now that we've used the status code and headers to communicate to the browser what to do with our response, we should probably talk about the most important part of many responses: the body.
The Response Body
The body is the final part of the response array. It is a string representing the actual information the user has requested.
When we make a request to /find-hippo, how does Rails convert the code we wrote in our controller and view into an html page about a specific hippo? Let's find out!
Content Negotiation
When we visit "skylight.io/find-hippo" in the browser, our Rails app serves up an html response. We can verify this by looking at the Content-Type response header:
The Lifecycle of a Response
How did Rails know to respond with html?
Rails looks first at any explicitly requested file-extensions, for example "skylight.io/find-hippo.html". If none is provided, which is the case with the request we made to "skylight.io/find-hippo", then it looks at the Accept request header.
Our Safari browser defaults this Accept request header to text/html, indicating it would prefer to receive the html content-type (formatted as a "MIME type") in the response. It also says that if there is no html version available, this browser is happy to accept an xml version instead.
The Lifecycle of a Response
The render method we call in our controller looks for the template with the extension matching the requested content-type, so in this case safari/hippo.html.erb. It also sets the Content-Type header to match the rendered body.
The Lifecycle of a Response
We want a json hippo too, so let's make a request to /find-hippo.json:
The Lifecycle of a Response
Oops! We don't have a template for a json hippo yet. We could add one, or we can add a respond_to block to handle the different formats:
The Lifecycle of a Response
Now, if we request /find-hippo.json, we get the json hippo:
The Lifecycle of a Response
Interestingly, browsers are not actually required to obey the Content-Type header and might try to "sniff" out the type based on the contents of the file. For this reason, Rails sets the X-Content-Type-Options header to nosniff to prevent this behavior:
The Lifecycle of a Response
Template Rendering
There are three ways our Rails controllers can generate a response. We've already talked in depth about two of those ways: the redirect_to and head controller methods generate responses with status codes, headers, and empty bodies. Only the render method generates a full response that includes a body.
For our /find-hippo example, let's say the template looks like this:
The Lifecycle of a Response
When we visit "skylight.io/find-hippo" and call render :hippo, the render method finds the appropriate template, fills in all of the blanks with our instance variables, then generates the body to send to the browser.
In order to accomplish this, Rails generates a "View Context" class specific to each controller. Here's a very simplified example of what that view context class for the Safari Controller looks like:
class SafariControllerViewContext < ActionView::Base
include Rails::AllTheHelpers
# link_to, etc.
include MyApp::AllTheHelpers
# current_user, etc.
def initialize(assigns)
assigns.each { |k, v| instance_variable_set("@#{k}", v) }
end
private
# Hey <%= current_user.name %>, meet <%= link_to @hippo.name, @hippo %>!
def __compiled_app_templates_hippo_erb
output = ""
output << "Hey "
output << html_escape(current_user.name)
output << ", meet"
output << link_to(html_escape(@hippo.name), @hippo)
output << "!"
output
end
end
(Note: To see the actual code, look in ActionView::Base, ActionView::Rendering, ActionView::Renderer, ActionView::TemplateRenderer, and ActionView::Template.)
When the View Context is initialized, Rails loops through all of the instance variables we have set in our controller (in this case @hippo) and copies them into the view context object for use in the template. These instance variables are known as "assigns."
The View Context class includes all of the helpers available from Action View (such as link_to) and all of the helpers we have defined in our app (such as current_user).
Each template is compiled into an instance method on the View Context class. Essentially, each template's method is a souped up string concatenation. In this case:
• Start the output string with "Hey ".
• Get self.current_user, which is available because we included all of our app helpers in the View Context class. Escape current_user.name since it might be user input, then append it to the output string.
• Add ", meet".
• Get the @hippo instance variable that we set when we initialized the view context. Use self.link_to to generate a link to the page for our hippo. Again, link_to is available because we included all of the Action View helpers as a module. Escape @hippo.name to use for the link text, then append the link to the output string.
• Add the "!" to finish the output string.
• Return the output string.
And put it all together:
The Lifecycle of a Response
Wow! We've finally found the elusive hippo, Phyllis, and she's 200 OK. Along the way, we've witnessed rare action, unimaginable scale, impossible locations and intimate moments captured from the deepest depths of Rails internals. We've travelled across the great text/plain, taking in the spectacular Action View as we found our way back to the browser.
Thank you for joining me while we unearthed...the amazing lifecycle of a Rails response.
]]>
<![CDATA[Announcing Skylight for GraphQL! 🤝]]>= `1.7`.]]>https://blog.skylight.io/announcing-skylight-for-graphql/5dbb4a6b9762b30038bfa1c4Fri, 01 Nov 2019 21:04:30 GMTAnnouncing Skylight for GraphQL! 🤝
Skylight 4.2.0 now includes GraphQL instrumentation! To use it, upgrade the Skylight gem and add 'graphql' to your probes list. We support graphql-ruby versions >= 1.7.
Announcing Skylight for GraphQL! 🤝
How does it work?
GraphQL is a new API implementation strategy that works somewhat differently from traditional Rails APIs. Instead of writing a controller action to represent each endpoint, every query sent to a GraphQL API is typically handled by a single controller and action. When it comes to profiling performance for this endpoint on Skylight, however, things get tricky. Though we may want to inspect the particular performance characteristics of one query, the waters are muddied if all of your queries are aggregated under this single endpoint. For customers using GraphQL, this is (unfortunately) exactly what they would have seen, since Skylight was originally written to serve the one-endpoint-per-action model.
Luckily, the GraphQL spec includes an optional Operation Name field that helps identify and group together particular queries. Skylight uses the operation name to determine the endpoint name and group your queries together. This means that even though all of your GraphQL requests are sent to a single controller, your queries will be aggregated by name in the Skylight dashboard! 🎉 Skylight's GraphQL instrumentation works best when naming queries because it helps us keep like data with like.
What about multiplexed queries?
Skylight names your endpoint based on all of the queries sent in a single request. For example, if you send two named queries together, your endpoint name will be a combination of those two query names.
Announcing Skylight for GraphQL! 🤝
Handling anonymous queries
Skylight groups all single anonymous queries under one endpoint. While your anonymous queries will still be tracked, you may notice that any spans under GraphQL::Schema#execute are ignored.
Announcing Skylight for GraphQL! 🤝
We intentionally ignore child nodes of anonymous queries because their divergent traces can’t be aggregated in a way that would provide actionable insights. We highly recommend using named queries with the GraphQL probe in order to get the most out of Skylight instrumentation!
You can learn more about this feature in our documentation. We hope you'll give it a try and tell us what you think!
If Skylight sounds useful to you, or if you have some endpoints like these ones that you'd like to investigate further, sign up today and get a free 30-day trial. Or, refer a friend and you'll both get $50 in credit!
]]>
<![CDATA[Using Skylight on Skylight]]>https://blog.skylight.io/skylight-on-skylight/5d03d052b09e2400370ef459Fri, 14 Jun 2019 20:39:53 GMTUsing Skylight on Skylight
We recently rolled out a new billing system that relies heavily on Stripe's Billing APIs. To avoid issues of inconsistency we try to rely on Stripe, whenever possible, as our single source of truth. This means that we frequently have to reach out to Stripe to get up-to-date information.
We realized early on that constantly reaching out to Stripe wasn't going to be good for performance, so we implemented a caching solution and figured that things were good to go. However, when we looked at the Skylight UI recently (yes, we actually use our own tool!) we noticed that some endpoints were much slower than we expected.
Using Skylight on Skylight
When we dove into the OrganizationsController#show endpoint, things didn't look great:
Using Skylight on Skylight
We could see that we had caching in place, but we were still having to call out to Stripe multiple times. Clearly, something was not working as we had expected.
There are a number of different places in our app where we could be calling out to Stripe so, to get some additional insight, we added custom instrumentation around these points to learn a bit more about where they were getting called from and what objects we were trying to fetch.
Using Skylight on Skylight
Now we had a bit better idea of what we were trying to fetch. In some of these places, we realized that we were actually bypassing the cache. This was easy to fix. We just needed to add some additional caching.
But that couldn't explain all of these cases! We were certain that some of these places shouldn't be calling out to Stripe after the cache was primed, yet here they were. After some further investigation, we realized that we weren't caching nil values. This meant that any time that we got a nil from Stripe (something that we did expect), we would continue to try to fetch from Stripe again, instead of using the nil value.
After adding additional caching and making sure we were caching nil values, we checked to see how we were doing:
Using Skylight on Skylight
Much better! (Those database queries could use some optimization, but perhaps we'll come back to those in another blog post. 😉)
Without Skylight, it would have taken much longer to realize how slow these endpoints had become. Maybe at some point, we would have logged into the app and realized that it felt a little slow. Perhaps we would have added more caching, but even then, we might have missed a few spots. We probably would have missed the issue of nil values not getting cached, just assuming that the remaining slowness was inherent in the setup.
The insights provided by Skylight enabled us to catch a problem before anyone complained, and better yet, helped show us what we needed to do to fix it.
If Skylight sounds useful to you, or if you have some endpoints like these ones that you'd like to investigate further, sign up today and get a free 30-day trial. Or, refer a friend and you'll both get $50 in credit!
]]>
<![CDATA[Announcing Skylight 4.0: Now with Background Jobs!]]>https://blog.skylight.io/background-jobs/5cd5e8f294e82200bf5d45c7Fri, 10 May 2019 22:27:38 GMTAnnouncing Skylight 4.0: Now with Background Jobs!
Skylight’s new Background Jobs feature helps you discover and correct hidden performance issues in your Sidekiq, Delayed::Job, and Active Job queues. Now available with the 4.0 Skylight agent.
While Skylight was originally developed to instrument web requests, we understand the web interface is only one part of your server-side application. For this reason, we've been hard at work preparing Skylight for Background Jobs!
Announcing Skylight 4.0: Now with Background Jobs!
This release is the culmination of over a year of work that touched every part of the Skylight ecosystem and was the motivation behind many of the features and improvements we've released over the past several months. Thank you to all of the Skylight Insiders who tried our the alpha and beta versions; your feedback, as always, was invaluable in preparing this release. We're excited to make Skylight 4.0 with background jobs available to all of our customers!
See Skylight for Background Jobs in action on one of our Skylight for Open Source apps: Octobox!
Neato! How do I turn it on? 🎉
Head on over to our background jobs documentation to get started!
Wait…I have questions. 🤔
No worries, we have answers! Read on to learn more about background jobs, why you need them, and how the team at Skylight went about implementing this new feature.
Why should I use background jobs?
We recommend moving slow code, such as third-party integrations, into background jobs in our Performance Tips documentation.
A typical web request finishes within a few seconds, with outliers ranging from dozens of seconds to perhaps a few minutes. Moving time-intensive work to the background—to be executed out-of-band of the typical request-response cycle—eliminates the pipeline coupling the work to the receiver.
For example, the story of user sign-up may differ significantly depending on which side of the looking glass you are on.
🔍 From the user’s point of view, it’s a pretty simple story: “As a user, I want to fill in my email and password, and then get started doing whatever it was I came here to do.” Easy peasy, right?
🔎 From the server’s point of view, there are many events that need to happen: syncing external accounts, setting up various pieces of internal data, mirroring the new account to a CRM, sending a confirmation email, etc. Whew…that might take a while!
These events are all important parts of the site’s functionality but would make the simple action of “signing up” appear unreasonably slow to the user. Not only could this be a bad first experience for the user, but it also risks locking up our web server or timing out the connection. Yikes! 😭
Luckily, developers have background jobs at our disposal. Each one of those events can be considered a separate piece of work, so when a new user signs up, we can tell our jobs processor to handle anything that is not immediately required to redirect the user to the post-sign-up experience. Not only does this allow a much faster response, it frees our web server to handle other traffic, and hopefully makes our user happy. 👍
Why should I track my background jobs’ performance?
While moving work into background jobs helps us improve web request response times, in terms of computing resources, we haven't achieved much else. We still need to do the same amount of work, plus some additional overhead (for example, whatever is necessary to power the background jobs framework itself).
This often means a new cluster of servers. 💸💸💸
Additionally, jobs can put even more load on the database, as we'll probably need to load some of the same records over and over again for each additional job we enqueue.
So while refactoring slow controller endpoints into background jobs may be a big win for your users, you still need to be aware of background application performance because it can have a big impact on your overall system performance. We developed Skylight for Background Jobs for precisely this reason—while jobs performance improvements may be less visible to your customers, we feel that they are just as important for maintaining your overall application health.
How the heck did you pull this off?
As mentioned above, implementation of Skylight for Background Jobs took over a year, with many detours along the way. For part one of this saga, see our post about Skylight Environments implementation, which was actually the first feature on the path to support jobs. After releasing Skylight Environments, we still had a lot of work to do. Here’s the rest of the story of Skylight for Background Jobs as told by Zach, who worked on the feature from start to finish.
The Collector
Skylight was originally designed to instrument and aggregate web request traces, so many of our time-series aggregation algorithms were optimized for data that fit certain criteria.
For example, we assumed that five minutes was a good theoretical maximum span duration, as most web servers include a default timeout well below this value. As it's pretty typical for most requests to finish within a few seconds, a five minute limit should be more than sufficient to handle even the grossest outliers…until now. It's not unusual for a single job to take several minutes or even hours, making our five-minute limit somewhat quaint.
Skylight's data collector is a large Java app ☕️ that accepts transaction-level trace data from all of the Skylight agents in the wild and emits aggregate traces to our UI on skylight.io/app. These aggregate traces track the distributions of the time spent in each transaction, with further aggregation done at the level of individual nodes within the trace. The aggregation and compression of these traces is what allows Skylight to store and query huge amounts of data efficiently, and had been tuned to handle traces of five minutes or less.
Last fall, Godfrey and I set about reading and learning about all of the bespoke digest algorithms and their associated data structures (neither of us had a hand in creating the original app), with the goal of increasing that five minute limit. (Have a look at our November outage post-mortem to get an idea of the operational concerns we need to consider when making these sorts of changes.)
After a few false starts and theoretical model revisions, we successfully increased our max span duration first to one hour, then to four hours (where we currently are). We're still hoping to increase this limit further, but first we want to focus on increasing the number of allowed child spans first to allow for greater fidelity in very long traces.
The Agent
Internally, Skylight has been measuring our own background jobs since late 2017, using an open-source community gem called sidekiq-skylight. A few months later, Peter started working on built-in support for Sidekiq instrumentation in our Ruby gem, and we switched to using our own Sidekiq middleware in early 2018. (Surprise! Skylight has had hidden support for Sidekiq instrumentation since version 2.0.)
We added support for Active Job and Delayed::Job a few months after that and set about testing the characteristics of the various Active Job processors to see how well they would play with Skylight. The good news is that most of them worked with minimal fuss, with the notable exception of Resque, which uses a fork-per-job model that causes Skylight to exit often before it has a chance to report its trace data (this is something we would still like to address).
We also started tracking the enqueuing of jobs on the web side, so you can now measure the actual benefit of enqueuing a job versus performing that work inline during a web request (enabled by default).
In addition to Ruby, the Skylight agent is also written in Rust—most importantly skylightd, the daemon that batches raw data from your server and sends it to our data collection infrastructure. On the Rust side of the agent, the biggest issue we had to address was another limitation that was originally designed around the web request model: traces could contain up to 2048 child nodes, but allocating any more than that would result in an error. This limitation is also reflected on the collector, so we decided that our best option to maintain compatibility with existing traces was to implement a “pruning” algorithm that could more-or-less intelligently discard nodes at the deepest level of the trace until the final count was under the limit (while this works well in practice, it's still on our roadmap of something we can continue to improve in the future).
The User Experience
As always, we prioritize providing a user experience that makes it easy to understand and act on your app’s performance data. Whenever we add a new feature, we are very careful that it doesn’t add unnecessary complexity to this user experience.
For this reason, one of the primary motivators for offering first-class background jobs support was to allow data about background jobs to be shown separately from data about web requests. The sidekiq-skylight gem—which many Skylight users were already using—lumps jobs data into the same bucket as web requests data. As you might imagine, this breaks many of Skylight’s aggregation features. ☹️
For example, the Response Timeline shows aggregate data about all of the responses in the selected time period. By lumping background jobs in with web requests, we might show “2 seconds” as a typical response time when your median web request response time is only 100 miliseconds and the median duration of your jobs is over a minute. In this case, “2 seconds” isn’t really telling you anything about your app’s performance.
Fortunately, most of the work to separate jobs data from web requests data was completed in order to release Skylight Environments. Specifically, we inserted the concept of an “App Component” between the “App” model and the data in the collector, which allows us to split an app’s data into multiple “buckets”—for example, “MyApp production web”, “MyApp staging web”, “MyApp production worker”, “MyApp staging worker”.
Splitting the background jobs UI from the web requests UI also allowed us to provide terminology specific to jobs. To this end, Krystan wrote a new “translation” helper that allows us to make context-aware changes to strings, so we can use different terminology on pages displaying background jobs.
Announcing Skylight 4.0: Now with Background Jobs!
You’ll also see your production background jobs data in the Skylight Trends feature, including Trends in the UI.
The Rollout
While the actual instrumentation of jobs was relatively straightforward, as one of the largest new features Skylight has ever rolled out, we spent a great deal of time developing techniques that would allow us to gradually onboard our existing customers without affecting the existing user experience. In general we focused on keeping changes small and individually manageable. Highlights include:
• Moving storage of UI-related feature flags to the server, which allowed us to integrate it with our permissions system. During the alpha and beta phases, the new “process type” drop down selector would only be shown to specific users, so the new server-side flags would allow us greater control over who could see that menu (previously, we would have asked users to individually enable flags to see new features).
• A new “survey” feature that allows us to collect information and automatically group cohorts of users in our CRM, which was used to impanel an alpha testing group for the background jobs feature.
• A restructuring of our agent authorization endpoint to ensure that only users with permissions to use the pre-release background jobs features would be able to collect data.
• Improved logic around deciding what background jobs usage is “billable”.
What else is new in 4.0?
In addition to adding support for background jobs, we also added:
• Active Storage instrumentation.
• Trace pruning, as mentioned above, for web requests in addition to jobs.
• Better instrumentation for Active Model Serializers and Action Controller content types.
• Improved error handling and logging.
• Changes necessary to be compatible with Rails 6!
Also, we dropped support for Ruby 2.2, which is end-of-life. For users using modern Ruby, the upgrade to 4.0 should be painless.
See the Skylight agent CHANGELOG for a full list of changes.
Thanks!
Throughout this process, we've used Skylight for Background Jobs to learn about and improve our own app's performance characteristics, and we've turned it into a feature that we hope you'll find useful as well. We're by no means finished, however. There are many improvements and planned features in the pipeline, so stay tuned for future updates!
Credits (in order of appearance)
Collector Infrastructure Improvements: Godfrey and Zach
App Management Infrastructure Improvements: Zach and Krystan
User Interface Rejiggering: Krystan
Agent Updates: Peter and Zach
Documentation and Bloggering: Zach and Krystan
Dogfooding and Bug-finding: Zach and the Skylight Insiders
Haven't tried out Skylight yet? Sign up for your 30-day free trial! Or refer a friend and you both get $50 in credit.
]]>
<![CDATA[The Lifecycle of a Request]]>https://blog.skylight.io/the-lifecycle-of-a-request/5cc9f8a194e82200bf5d45b3Thu, 02 May 2019 21:00:00 GMTThe Lifecycle of a Request
This post is part of a series. Check out Part II: The Lifecycle of a Response here!
This post is a write-up of the talk we gave at RailsConf 2019. You can find the slides here.
The Lifecycle of a Request
Most Rails developers should be pretty familiar with this work flow: open up a controller file in your editor, write some Ruby code inside an action method, visit that URL from the browser and the code you just wrote comes alive. But have you thought about how any of this works? How did typing a URL into your browser's address bar turn into a method call on your controllers? Who actually calls your methods?
A journey into the Interwebs
The Lifecycle of a Request
Let's say you are meeting someone for lunch. "Meet at Pastini" probably works for your co-workers who go there a lot, but may not be so helpful for your out-of-town friend. Instead, you should probably provide the street address of the restaurant, that way, they can give it to the cab driver, or just ask a local for directions.
Computers work much the same way. When you type a domain name like that into your browser, the first order of business is for the browser to connect to your server. While domain names like "skylight.io" are easier for us to remember, it doesn't help your computer find your server. To figure out how to get there, they need to translate that name into an address for computer networks, this is the IP address. (It stands for Internet Protocol address, in case you are wondering!)
It looks something like 34.194.84.73, you've probably come across it at some point. With this kind of address, computers can navigate the interconnected networks of the Internet and find their way to their destinations.
DNS, which stands for Domain Name System, is what helps our computers translate the domain name into the IP address they use to find the correct server. You can try it for yourself with a utility called dig on your computer (or with this online version).
; <<>> DiG 9.10.6 <<>> skylight.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32689
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;skylight.io. IN A
;; ANSWER SECTION:
skylight.io. 59 IN A 34.194.84.73
;; Query time: 34 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Mon Apr 29 14:50:34 PDT 2019
;; MSG SIZE rcvd: 56
The output looks a bit intimidating, but the main thing to see here is in the answer section, it resolved the "skylight.io" domain into the IP address 34.194.84.73.
The DNS is a registry of domain names mapped to IP addresses
When you buy/own a domain you are in charge of setting up and maintaining this mapping, otherwise, your customers won't be able to find you.
Okay, once we have the IP address of the server, our browser can connect to it. The way that the browser connects to the server is actually pretty interesting, you can think of opening a connection between the two like picking up a phone and dialing someone's number.
In fact, we can try this one too! There is this program on your computer called telnet, that lets you open a "raw" connection to any server. For example, telnet 34.194.84.73 80 would try to open a connection to the server we found earlier, on port 80, which is the default HTTP port.
The Lifecycle of a Request
Once we have connected, we have to say something, but what do we say? The browsers and the servers have to agree on a language for "speaking" to each other, so that they can understand what one another is asking for. This is where HTTP comes in; it stands for hyper text transfer protocol, which is the language that both browsers and web servers can understand.
To make the request for "skylight.io/hello", here is the simplest request that we could make. It specifics that it is a GET request, for the path /hello, using the HTTP protocol version 1.1, and it is for the host "skylight.io":
GET /hello HTTP/1.1
Host: skylight.io
If we carefully type this into our telnet session (the trailing new line is important to signify the end of the request), we may get a response from the server that looks like this:
HTTP/1.1 200 OK
Content-Type: text/plain
Content-Length: 11
Date: Thu, 25 Apr 2019 18:52:54 GMT
Hello World
It specified the request was successful, gives a bunch of header information, and finally, "Hello World" – the text we rendered from the controller.
HTTP is a plain-text protocol, as opposed to a binary protocol, which makes it easy for humans to learn, understand and debug. It provides a structured way for the browser to ask for web pages and assets, submit forms, handle caching, compression and other mundane details.
Just like your phone line, the connection between the browser and the server is unencrypted.
The request goes through a lot of places to get to the other side: the conference wifi routers, the convention center's routers, our Internet provider, the server’s hosting company, and many other intermediate networks in between that helped forward the request along to the right place. This means, a lot of parties along the way have the opportunity to eavesdrop in on the conversion. But maybe you don’t want others to know what conversation you’re having?
No problem, you can just encrypt the contents of the conversation. It will still pass through all the same parties, and they will still be able to see that you are sending each other messages. But, those messages won’t make sense to them, because only your browser and the server have the keys to decrypt these messages.
This is known as HTTPS – the S makes it secure ;) Notably, it's not a different protocol from HTTP. You are still speaking in the same plain-text protocol that we saw earlier, but before before the browser sends the message out, it encrypts it, and before the server interprets the message, it decrypts it.
The encryption/decryption is done by using a secret key that both the browser and the server have agreed upon and no one else knows about. But how do the browser and server pick what keys to use for encryption/decryption without giving those keys away while all the other parties are listening in? Well, that's a topic for another time.
The server
The Lifecycle of a Request
By now, your browser has successfully connected to the server and asked it for a specific web page. How did it generate this response?
First of all, what kind of server is this? It’s a "web server", which really just means that it "speaks" HTTP, as we saw earlier. Some examples are apache, nginx, passenger, lighthttpd, unicorn, puma, and even webrick; some are written in Ruby, others are written in system languages like C.
Their job is to parse and "understand" the request, and make a decision on how to service that request. For simple requests, like serving static assets, you can easily just configure the web server to do that for you.
For example, let's say that we want to tell the web server that whenever a browser requests anything under "/assets/", then the web server should try to find that file in my app's "/public/assets" folder. If it exists, it should serve that with compression, otherwise, it should return a 404 not found page.
Depending on which web server you are using, there are specific configuration languages or syntax you might want to use. For example, if you are using nginx, you would probably put something like this in nginx.conf:
location /assets {
alias /var/myapp/public/assets;
gzip_static on;
gzip on;
expires max;
add_header Cache-Control public;
}
The Lifecycle of a Request
For more complicated things though, it gets trickier.
For example, we might want to tell our web server: "Hey, whenever a browser goes to "/blog", go to the database and get the the 10 most recent blog post, make them look pretty, maybe show some comments too, and throw in a header and footer, a nav bar, some JS and CSS, and off you go!"
Well, this is probably something that's too complicated to express in the web server's configuration language. But hey, that's what we have Rails for. So really, we want to tell the web server that it needs to hand these requests off to Rails for further processing, but how is the web server going to communicate with Rails?
The Lifecycle of a Request
In Ruby, there are many ways to communicate this kind of information. Rails could potentially register a block with the server, or the server could call a method on Rails. The server could pass the request information as method arguments, environment variables, or maybe even global variables? And if we do that, well then, what kind of object should these be? On the flip side, how will Rails communicate back to the web server?
Ultimately, all of these options work, and at the end of the day, which one you pick is not nearly as important as everyone agreeing on the same convention. That's why Rack was born – to present a unified API for web servers to communicate with Ruby web frameworks, and vice versa. By implementing the Rack protocol, all Ruby frameworks that conforms to that convention will work seamlessly with these web servers.
The Lifecycle of a Request
Rack is a simple Ruby protocol/convention that does a few things. The web server needs to tell the web framework, "Hey, here a request for you to handle. By the way, here are the deets for the request: paths, http verb, headers, etc." On the other hand, the framework needs to tell the server, "Hey, that’s cool, I’ve handled it. Here is the result... the status code, headers, and body."
In order to remain lightweight and framework agnostic, Rack picked the simplest possible way to do this in Ruby. It notifies the web framework using a method call, communicates the details as method arguments, and the web framework communicates back by return values from the method call.
In code, that looks like this.
env = {
'REQUEST_METHOD' => 'GET',
'PATH_INFO' => '/hello',
'HTTP_HOST' => 'skylight.io',
# ...
}
status, headers, body = app.call(env)
status # => 200
headers # => { 'Content-Type' => 'text/plain' }
body # => ['Hello World']
First the web server prepares a hash, which is conventionally called the "env hash". The env hash contains all the information from the HTTP request – for example, REQUEST_METHOD contains the HTTP verb, PATH_INFO contains the request path and HTTP_* has the corresponding header values.
On the other hand, the "app" or framework must implement a #call method. The server will expect it to be there and invoke it with the env hash as the only argument. It is expected to handle the request based on the information in the env hash and return an array with exactly three things in it (a.k.a. "a tuple of three").
So what are the three things?
The first element is the HTTP status code – 200 for a successful request, 404 for not found, etc. The second element is a hash containing the response headers, such as Content-Type. The third and final element in the array is the response body. We might think that the body should be a string, but it's actually not! For some technical reasons, the body is an "each-able" object – a object that implements a #each that yields strings. In the simple case, you can just return an array with a single string in it.
The Lifecycle of a Request
So, let's see this in action! Before we dive into Rails, let's try to build a simple Rack app.
# app.rb
class HelloWorld
def call(env)
if env['PATH_INFO'] == '/hello'
[200, {'Content-Type' => 'text/plain'}, ['Hello World']]
else
[404, {'Content-Type' => 'text/plain'}, ['Not Found']]
end
end
end
This is probably the simplest Rack app that we could build. It didn't have to subclass from anything, just a simple class that implements #call. It looks at the request path from the env hash, if it matches /hello exactly, it renders a plain text "Hello World" response, otherwise, it renders a 404 "Not Found" error response.
Alright, now that we have written our app, how do we use it? How do we make it do things? Recall that Rack is only a protocol that web servers can implement, so we will need to wire up our app to a Rack-aware web server.
Conveniently, the rack gem, a collection of complimentary utilities for implementing and using the Rack specification, comes with an example web server called rackup that can do this for us. rackup understands a config file format called config.ru:
# config.ru
require_relative 'app'
run HelloWorld.new
This is basically a Ruby file with some extra configuration DSL. Here we are requiring our app file, constructing an instance of our HelloWorld app and passing it to the rackup server using the run DSL method.
With that, we can run the rackup command from within the directory of our config.ru file and it'll attach the server to port 9292 by default. If we visit http://localhost:9292/hello, we will see "Hello World", and if we navigate to http://localhost:9292/wat we will see the "Not Found" error.
Now, let's say we want to add a redirect from the root path http://localhost:9292/ to http://localhost:9292/hello. We can modify our app like so:
# app.rb
class HelloWorld
def call(env)
if env['PATH_INFO'] == '/'
[301, {'Location' => '/hello'}, []]
elsif env['PATH_INFO'] == '/hello'
[200, {'Content-Type' => 'text/plain'}, ['Hello World']]
else
[404, {'Content-Type' => 'text/plain'}, ['Not Found']]
end
end
end
This works, but it doesn't scale very far. If we keep adding things here, this if/elsif/else/end chaing is going to get very long. Redirecting is also a pretty common thing that we may want to reuse in different parts of our application. Wouldn't it be great if we can implement this functionality in a modular, reusable and composable manner?
Of course we can!
# app.rb
class Redirect
def initialize(app, from:, to:)
@app = app
@from = from
@to = to
end
def call(env)
if env["PATH_INFO"] == @from
[301, {"Location" => @to}, []]
else
@app.call(env)
end
end
end
class HelloWorld
def call(env)
if env["PATH_INFO"] == '/hello'
[200, {"Content-Type" => "text/plain"}, ["Hello World!"]]
else
[404, {"Content-Type" => "text/plain"}, ["Not Found!"]]
end
end
end
Here, we are able to keep HelloWorld exactly the way it was before. Instead, we added a new Redirect class that is responsible for manging that one single responsibility. If it found a matching path, it will issue a redirect response and that would be the end. If it didn't, it delegates to the next app that we passed to it.
To wire this up, we change our config.ru like so:
require_relative 'app'
run Redirect.new(
HelloWorld.new,
from: '/',
to: '/hello'
)
We constructed an instance of the HelloWorld app and passed it to the Redirect app.
With this, we have implemented a Rack middleware! Middlewares are not technically part of the Rack spec – as far as the web server is concerned, there is only one app (Redirect), it just happens to call another Rack app as part of it's #call method, but the web server doesn't need to know that.
This middleware pattern is so common that config.ru has a dedicated DSL keyword for it:
require_relative 'app'
use Redirect, from: '/', to: '/hello'
run HelloWorld.new
With the use keyword, we can clean up the nesting. Neato!
The middleware pattern is very poweful. Without writing any extra code, we can beef up our toy app to add compression, HTTP caching and handle HEAD requests just by adding a few middleware from the rack gem:
require_relative 'app'
use Rack::Deflater
use Rack::Head
use Rack::ConditionalGet
use Rack::ETag
use Redirect, from: '/', to: '/hello'
run HelloWorld.new
You can imagine building up a very functional app this way.
Rails <3 Rack
Finally, we are ready for Rails!
Of course, Rails implements Rack. If you look at your Rails app, it should come with a config.ru file that looks like this:
require_relative 'config/environment'
run Rails.application
Even though config.ru originated from rackup, it is also understood by a few other web servers and services like Heroku, so it's useful for Rails to include it by default.
We learned that we are supposed to pass a Rack app to the run keyword, so Rails.application must be a Rack app that responds to #call! Well, why don't we try it from the Rails console!
The Lifecycle of a Request
Instead of building a spec-complient env hash by hand, we can use the Rack::MockRequest.env_for utility method from the rack gem. It takes a URL and takes care of the rest for you. Calling Rails.application.call with this env hash yields the expected tuple of status code, headers and body. It even prints the familiar request log to the console. Cool!
One thing that stands out from the config.ru file in our Rails app is that it didn't have any use statements. Does Rails not use any middlewares? No! In fact, there is a handy command that you can run to see all the middlewares in your app using the familiar config.ru syntax:
$ bin/rails middleware
use Rack::Sendfile
use ActionDispatch::Executor
use ActiveSupport::Cache::Strategy::LocalCache::Middleware
use Rack::Runtime
use Rack::MethodOverride
use ActionDispatch::RequestId
use ActionDispatch::RemoteIp
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use ActionDispatch::DebugExceptions
use ActionDispatch::Callbacks
use ActionDispatch::Cookies
use ActionDispatch::Session::CookieStore
use ActionDispatch::Flash
use ActionDispatch::ContentSecurityPolicy::Middleware
use Rack::Head
use Rack::ConditionalGet
use Rack::ETag
use Rack::TempfileReaper
run Blorgh::Application.routes
We can see that Rails has implemented a lot of its functionalitiy in middlewares, such as cookies handling. This is cool, because if we are implementing an API server, we can just remove these unnecessary middlewares. But how?
Recall that use statement is just a convenience in for building up your app in config.ru, the web server only "sees" the outer-most app anyway. Rails have a different convenience for manging middlewares in config/application.rb:
# config/application.rb
require_relative 'boot'
require 'rails/all'
Bundler.require(*Rails.groups)
module Blorgh
class Application < Rails::Application
# Disable cookies
config.middleware.delete ActionDispatch::Cookies
config.middleware.delete ActionDispatch::Session::CookieStore
config.middleware.delete ActionDispatch::Flash
# Add your own middleware
config.middleware.use CaptchaEverywhere
end
end
Finally, our app!
So, we looked at the middlewares, but where's our "app"? From the output of bin/rails middleware, we know that use is for middlewares and run is for the app, so Blorgh::Application.routes must be it!
The Lifecycle of a Request
Running the same test in the Rails console, we can see that if we replace Rails.application.call with Blorgh::Application.routes, everything still works. So what does this rack app do, and where did it come from?
This Rack app looks at the request URL, match it against a bunch of routing rules to find the right controller/action to call. Rails generates this app for you by Rails based on your config/routes.rb.
# config/routes.rb
Rails.application.routes.draw do
resources :posts
end
The resources DSL should look pretty familiar to most Rails developers. It's a shorthand for defining a bunch of routes at once. Ultimately, it expands into these seven routes:
# config/routes.rb
Rails.application.routes.draw do
# resources :posts becomes...
get '/posts' => 'posts#index'
get '/posts/new' => 'posts#new'
post '/posts' => 'posts#create'
get '/posts/:id' => 'posts#show'
get '/posts/:id/edit' => 'posts#edit'
put '/posts/:id' => 'posts#update'
delete '/posts/:id' => 'posts#destroy'
end
For example, when you make a GET request to /posts, it will call the PostsController#index method, if you make a PUT request to /posts/:id, it will go to PostsController#update instead.
So, what is this posts#index string? Well, we know it stands for the index action on the PostsController. If you follow the code in Rails, you will see that it eventually expands into PostsController.action(:index). So what is that?
Here is a much simplified version of the Action Controller code:
class ActionController::Base
def self.action(name)
->(env) {
request = ActionDispatch::Request.new(env)
response = ActionDispatch::Response.new(request)
controller = self.new(request, response)
controller.process_action(name)
response.to_a
}
end
attr_reader :request, :response, :params
def initialize(request, response)
@request = request
@response = response
@params = request.params
end
def process_action(name)
event = 'process_action.action_controller'
payload = {
controller: self.class.name,
action: action_name,
# ...
}
ActiveSupport::Notifications.instrument(event, payload) do
self.send(name)
end
end
end
We see our action class method on the top there. You can see that it returns a lambda. The lambda takes an argument called env. What’s that?
SURPRISE It’s a hash! And what does the lambda return? An array! And by the way, SURPRISE lambdas respond to #call! Yup, it’s a Rack app! Everything is a Rack app!
Finally, putting everything together, you can imagine the routes app is a rack app that looks something like this:
class BlorghRoutes
def call(env)
verb = env['REQUEST_METHOD']
path = env['PATH_INFO']
if verb == 'GET' && path == '/posts'
PostsController.action(:index).call(env)
elsif verb == 'GET' && path == '/posts/new'
PostsController.action(:new).call(env)
elsif verb == 'POST' && path == '/posts'
PostsController.action(:create).call(env)
elsif verb == 'GET' && path =~ %r(/posts/.+)
PostsController.action(:show).call(env)
elsif verb == 'GET' && path =~ %r(/posts/.+/edit)
PostsController.action(:edit).call(env)
elsif verb == 'PUT' && path =~ %r(/posts)
PostsController.action(:update).call(env)
elsif verb == 'DELETE' && path = %r(/posts/.+)
PostsController.action(:destroy).call(env)
else
[404, {'Content-Type': 'text-plain', ...}, ['Not Found!']]
end
end
end
It matches the given request path and http verb against the rules defined in your routes config, and delegates to the appropriate Rack app on the controllers. Good thing you don't have to write this by hand. Thanks Rails!
Now you might be wondering, how does Rails generate this from your routes config to do this mapping, and route every request efficiently? SURPRISE! There's a talk for that, too. Check out Vaidehi's talk from last year's RailsConf.
Ok, now that we know #everythingisarackapp, we can mix and match things. Here are some Pro Tips™:
1. Did you know that you can route a part of your Rails app to a Rack app, just like that?
Rails.application.routes.draw do
get '/hello' => HelloWorld.new
end
2. In fact, now that we learned about lambdas, we can even write that inline!
Rails.application.routes.draw do
get '/hello' => ->(env) {
[200, {'Content-Type': 'text/plain'}, ['Hello World!']
}
end
3. You may think that's a terrible idea, but in fact you've probably used this functionality before – how did you think the router's redirect DSL works? SURPRISE, it returns a rack app!
Rails.application.routes.draw do
# redirect(...) returns a Rack app!
get '/' => redirect('/hello')
end
4. You can even mount a Sinatra app inside a Rails app! You may not know this, but the Sidekiq web UI is was written in Sinatra, so you may already have a Sinatra app running inside your Rails app!
Rails.application.routes.draw do
mount Sidekiq::Web, at: '/sidekiq'
end
Update: Since Sidekiq 4.2, the web UI was migrated to a custom framework to reduce external dependencies. Of course, it still uses the Rack protocol!
The migration pull request makes for an interesting case study of what it takes to build a minimal version of Sinatra on top of what we learned here about the Rack protocol. Among other things, it handles basic routing, view rendering, redirects and more.
5. Of course, you can also go the other way around an mount your Rails app inside a Sinatra app. We'll leave that up to your imagination.
With what we learned, we can even replace the controller#action string with this:
Rails.application.routes.draw do
get '/posts' => PostsController.action(:index)
get '/posts/new' => PostsController.action(:new)
post '/posts' => PostsController.action(:create)
get '/posts/:id' => PostsController.action(:show)
get '/posts/:id/edit' => PostsController.action(:edit)
put '/posts/:id' => PostsController.action(:update)
delete '/posts/:id' => PostsController.action(:destroy)
end
...or we can paste the output of bin/rails middleware into our config.ru file!
Now, we wouldn't recommend actually doing either of those in your Rails app – it bypasses autoload and some performance optimizations, prevents gems from adding middlewares, is hostile to future changes in Rails, etc. Nevertheless, it's very cool to know how everything fits together!
The Lifecycle of a Request
After all that, now we've finally made it back into the controller action that we started with. But wait, how does render plain... get turned into the response tuple required by the Rack spec? Well, we don't have time for that today, but maybe stay tuned for a "The Lifecycle of a Rails Response" talk/blog post!
How does Skylight work?
What we learned so far is that frameworks aren't magic. They're just a layer of sugar on top of a consistent, well-defined primitive. Conventions help you learn how to use Rails and share your skills with other developers, but on top of that, they give the community the ability to write tools that everyone can share.
For example, Skylight needs to measure how long your entire request took. What better way to do that than a middleware?
$ bin/rails middleware
use Skylight::Middleware
use Rack::Sendfile
use ActionDispatch::Executor
...
run Blorgh::Application.routes
Convention over configuration is also more than just how you build Rails apps. Rails conventions allow Skylight to collect detailed information about your web app without needing a line of Skylight configuration.
Earlier on, we looked at how Rails dispatches actions, in the simplified version of ActionController::Base#process_action. Inside that method, when Rails dispatches actions to your controller method, it uses a built-in instrumentation system called ActiveSupport::Notifications to notify libraries like Skylight that something interesting has happened. This API is how Skylight gets the name of your endpoint without any configuration.
The Lifecycle of a Request
Skylight does way more than give you average response times. We give you a detailed aggregate view of your entire request. We leverage ActiveSupport::Notifications and community conventions to provide conventional descriptions not only for Rails things like template rendering and Active Record timing, but also for popular HTTP libraries, caching libraries, and alternative database libraries (like Mongoid).
By default, we only show you important parts of your request, so you can focus on speeding up what matters. In this example, you should probably focus on AppSerializer if you want to speed up this endpoint. But we still collect lots more information that you can see if you want to dig in, including all of the Rack middleware used by your app.
The Lifecycle of a Request
This talk is part of a series. Check out The Lifecycle of a Response!
]]>
<![CDATA[November Outage Post-Mortem]]>https://blog.skylight.io/november-outage-post-mortem/5cc9f70a70712a0017b35326Tue, 04 Dec 2018 17:00:00 GMT
For the last couple of months, we have been investing in improving our operations and infrastructure here at Skylight. As our efforts begin to bear fruit, we have had a pretty good run without major incidents – until last week where we were hit by one of the biggest outages in our recent history. As they say, it never rains, but oh does it pour!
Incident Summary
Between November 28 and November 30 (Pacific Time from here on), we experienced a major outage. Our data processing sub-system was offline for 17 hours, the longest in our history. During this time, the Skylight agent was sending data with no impact to customer applications. We built the backend systems in compartments so the data collection sub-system is not affected when the data processing sub-system experiences downtime. The Skylight UI was also unaffected, beyond the fact that there was no realtime data to show.
While our architecture meant that we were unlikely to lose data, the extensive downtime accumulated a huge amount of data to be processed once the system was back online. Since this magnitude of backlog is very rare (a first, in fact), our infrastructure was not well-tuned to handle this type of workload. As a result, we were unable to process data as quickly as we would have liked.
After the initial recovery, some of our customers experienced multi-hour data processing delays (time between data was sent from the agent and when they become available on the Skylight UI) for the next two days. This is certainly not the experience we aim for, and we are sorry for letting you down. This post-mortem serves as a detailed report of what happened, and what we are doing to prevent it from happening again.
Detailed Timeline
This section gives an overview of the key events that contributed to the outage. Most of these facts were not known at the time of occurrence.
November 27 (Tuesday)
• At 5:18 PM, Ubuntu published a new OpenJDK build into the security channel.
• Following the standard Ubuntu (and Debian) best practices, our servers are configured to automatically apply security updates. Over the next couple of hours, the security update was picked up and applied on all our servers without human intervention.
• Around 11 PM, one of the worker servers encountered an unrelated Java exception during processing, which caused our monitoring system to automatically kill and restart the process. This is a routine procedure and our system is designed to tolerate and recover from these kinds of failures. However, since this was the first restart after the security update, the data processing application was running the new OpenJDK build for the first time.
• At 11:09 PM, the on-call engineer was paged to handle a disk-space issue on a worker server.
• Shortly after, we detected an elevated error rate, caused by OS-level SIGBUS errors ("a fault occurred in a recent unsafe memory access operation in compiled Java code") and a mix of other application-level exceptions (e.g. integer underflow), all of which originated from within a dependency used to maintain an off-heap query cache. We later determined these errors had the same root cause.
• The new errors quickly overwhelmed the worker server. The data processing application was stuck in a "restart loop" and was unable to make meaningful progress. The resulted in a significant loss in data processing capacity which affected about 25% of customer applications.
• At 11:20 PM, the on-call engineer responded to the alert and began investigating. At first, the focus was to triage the disk-space issue that was brought to our attention. We observed that the off-heap query cache was taking up a lot (but not all) of available disk space, but it seemed to have settled with no signs of growth or fluctuation. Even with that oversized cache, we appeared to have a reasonable (if only barely) buffer of free space left, so it was not obviously an urgent issue.
• We shifted into investigating the stream of the far more unusual new errors and restoring the worker’s processing capacity. For the rest of the hour, we attempted the routine troubleshooting and recovery procedures—rebooting, cycling hardware, provisioning extra disk space, etc—to no avail.
November 28 (Wednesday)
• Between 12 AM and 1 AM, the remaining worker servers were restarted for a variety of routine reasons. At this point all the servers were running the new OpenJDK build and were stuck in similar restart loops. This resulted in a total loss of data processing capacity.
• At the time, the root cause of the failure was not known. Since the worker servers were largely isolated from each other, we had been assuming up until this point that this was an isolated problem restricted to the first worker. These workers were set up to process different, independent shards of customer data, so our leading theory was that we had some form of corrupted data, caused by an agent bug. The spread of the failure was quite surprising and extremely puzzling.
• Since we were focusing on recovering the first server thus far, we missed the window of opportunity to compare and identify any differences between a "healthy" and "unhealthy" worker server. By the time we looked into the other servers, they all exhibited similar failure modes with no apparent links to be found in the application logs.
• Since the symptoms were consistent with data corruption (invalid data was produced somewhere upstream resulting in unaccounted for conditions somewhere down the chain), this was the main focus of our investigation. This kind of problem is extremely difficult to debug (especially at 2 AM!), as the cause and effect can sometimes be very far apart, making usual debugging techniques ineffective. We resorted to code reading—both in our application codebase and in the third-party dependency—carefully tracing all the data paths to identify ways this sort of problem could manifest, as well as reviewing all recent commits.
• When morning rolled around, additional engineers got involved in the situation, handling status updates, customer communications, etc. Our status page assumed a maximum data processing delay of six hours. By this point, we had reached that limit and the figure was not accurate. Perhaps this was too much optimism on our part, but the reason a cutoff was chosen here was to avoid potentially generating an unbounded amount of load on the collector (querying a lot of historic data) during an already bad outage situation.
• At this point, even though we still had not identified a root cause, we were pretty confident that the problem was related to the off-heap query cache. We starting evaluating a plan to operate with the cache completely disabled. This was not something we did lightly, as we knew that behavior could diverge from what was typically possible on production. We also knew that this could put an unprecedented amount of read load on the database, which our database was not tuned for. But since we were running low on other leads, we prepared a patch for this.
• At around 11 AM, we finished drawing up a plan and decided to test the patch to disable the query cache on a single worker server. While it did not exhibit cache-related issues, it got stuck in a restart loop due to a new exception. Unfortunately, this time it was a garden-variety neighborhood NullPointerException exception, which took us a while to triage.
• We determined that this error was caused by some missing data in the database. The exact cause was unknown at the time, but we figured out how to work around it with another patch. We realized (way) later that this was because we were persisting transient 1 minute rollups with a 6-hour TTL (expiration time). Normally, we would finalize the rollup window soon after and rewrite the data with a much longer TTL, matching our data retention policy. Since we were down for more than 6 hours at this point, the transient data had already expired. The problem itself wasn’t particularly fatal, but we had never experienced a downtime long enough to have accounted for this scenario.
• At around 2 PM, we successfully restarted the first worker server. We resumed data processing for some customers and assessed the extra workload's impact on the database. After the longest 15 hours at Skylight, we breathed our first sigh of relief and took breaks for food and coffee.
• As it turned out, the concern over the extra database workload was mostly unnecessary. Due to other issues we experienced in the past (which are now fixed), we ended up provisioning a lot of extra database capacity. This came in pretty handy for the situation as it allowed the database cluster to handle the extra workload reasonably well.
• By 5 PM, we felt confident enough to restart another worker server. By 7 PM, we had all of our worker servers back online.
• Due to the six hour reporting limit on the lag monitoring, we didn't have very good visibility into the backlog situation in terms of wall clock time. We did, however, have metrics in terms of raw bytes from the input side of the pipeline. We knew that we were burning through backlog at a positive rate (i.e. our data processing rate was higher than our ingestion rate), so we were no longer at risk of any data loss (which would only happen if we were to over-run the ingestion buffer) and it was "just a matter of time" until we were fully caught up. We decided that it was safest to let things settle overnight rather than to make any more last-minute changes with our sleep-deprived brains.
• At this point, we all went home* for dinner and had a good night's sleep. (* Yehuda and I were at the Bay Area for TC39, and Peter worked from home, so we only "went home" metaphorically.)
November 29 (Thursday)
• By daytime, the data processing delay on the first worker server had reduced to under the 6 hour mark, which was a good sign. However, this didn't mean we were 6 hours wall clock time away from fully catching up. The volume of data that we process at Skylight is directly tied to the amount of traffic our customers’ applications receive. In aggregate, this adds up to a huge daytime traffic bias – we often process several times more data at (US) daytime "peak hours".
• While we had provisioned more than enough processing capacity to handle the typical peak traffic, there wasn’t much spare capacity left to process the backlog. It also didn’t help that we had the query cache disabled, which meant we were operating at somewhat degraded performance. The end result was that while we were able to catch up significantly during the night (we were once over 17 hours behind in processing data!), the gap didn't narrow significantly during the day.
• At around 8:30 AM, we deployed a patch to our monitoring system that increased the delay reporting window. At this point, most of the workers were caught up and somewhere within the 6 hour window, where they continued to hover for the rest of the work day. During this period, our customers experienced various levels of delayed access to their performance data (e.g. only data from the morning would be available when checking the app in the afternoon). Once again, we are truly sorry for the confusion and inconvenience that this caused.
• We looked into provisioning extra capacity to get us through the hump, but ultimately decided against it. In hindsight, this may have been an incorrect judgement call, but, at the time we made it, we were both more optimistic about the processing rate and more conservative about introducing unnecessary variables and sources of errors into the system. Throughout this incident, our top priority was to avoid data-loss. At the time, we still had not identified the root cause, and we were unsure how much extra load the database cluster could handle. Since it generally takes a couple of hours to provision extra servers and reconfigure our pipeline, we believed the payoff was probably not worth the extra risk.
• We also attempted to re-enable the query cache, but we ran into the same issues as before.
• Since there wasn’t much else to do to speed things up on the processing side, we shifted focus back to investigating the root causes for the incident for the rest of the day.
• By 5 PM, the first worker was fully caught up, with the remaining workers hovering around the 5 hour mark.
November 30 (Friday)
• By 6 AM, all but one of the workers were fully caught up, while the last worker was hovering around the 2 hour mark (due to unbalanced sharding). Based on our experience from Thursday, we knew that this would probably remain the case for the rest of the day. At this point, we felt that we understood the capacity of the system fairly well and decided to provision extra capacity and rebalance the shards.
• By noon, we deployed the infrastructure changes successfully.
• By around 4 PM, all workers were fully caught up.
• By the end of day, we completed our root cause analysis (see below for the findings).
Root Cause Analysis
Once again, most of this information was not known at the time of their occurrences. This section is written in an order optimized for understanding the problem.
A month ago, Ubuntu published an OpenJDK security update to address a variety of CVE vulnerabilities. This version was based on the upstream OpenJDK 8 Update 181 release. Unfortunately, it was later discovered that this release also introduced a regression. As far as we know, we were not affected by that particular issue, as we have been running this in production for about a month at this point.
To address the issue, Ubuntu published the aforementioned OpenJDK update last Tuesday. Based on the Ubuntu Security Notice, there don't seem to be other notable security patches in this release other than to address the regression caused by the October update. However, this release is based on the newer upstream OpenJDK 8 Update 191 release, which contained a variety of other bugfix patches.
Among those patches was a fix for JDK-8168628. On the surface, the symptoms of this bug were quite similar to our situation: it involves SIGBUS faults while using mmap, which our off-heap query cache ultimately relies on under the hood. However, in practice this patch had the opposite effect for us: we did not experience any of those issues before the patch, and now we do.
To understand why, we need to explain how our off-heap query cache works. For those unfamiliar, the POSIX mmap API is a way to memory-map a file. This allows you to arbitrarily address contents of a big file as if they are just content in memory (e.g. using pointer arithmetic and dereferencing, as opposed to using the regular file-oriented APIs such as lseek and read).
When accessing an address for the first time, the kernel will lazily load the relevant part of the file into memory, usually one or more pages at a time. Likewise, when running low on memory, portions of the memory-mapped file can be flushed to disk and unloaded from RAM. In a way, it can act like an application-level swap space.
This is perfect for our use case. As our data (other than the transient rollups mentioned above) are immutable-once-written, this allowed us to maintain a local cache larger than the available amount of working memory alone would allow. Even when we do have to read from disk, it will still be slightly faster than making a trip to the database and will reduce the read load on the database.
On each worker server, we have configured two such local, equally sized, off-heap caches via Chronicle Map to store two different types of query data. The exact size of the caches are heuristically (but deterministically) calculated by the library using static configuration we provide.
Later introspection determined the size of each of these caches was around 90 GB each (180 GB combined), which added up to more than the disk space we had provisioned (100 GB dedicated to the caches) on the worker servers.
This was not a problem for us in practice, as we rely on sparse file support in XFS, which lazily allocates backing disk space as needed. Under typical operating load, our query caches are running at around 10-20% full at all time, which means we are normally only using around 20-30 GB disk space, leaving a pretty healthy margin.
Furthermore, because the content of the cache is tied to the lifetime of the data processing application process, in the extremely unlikely event that we run out of disk space for the query cache (this has never happened before, as far as we are aware), it will simply crash the process and instantly empty the cache/disk and start over again.
With all that said, even though it does not cause any problems in practice, you could argue that this is a misconfiguration on our part, as we also don't have any particular reason to configure the cache to be bigger than the available disk space. It was simply one of those cases where you plugged in some initial guesstimates which worked well and never had a reason to go back and fine-tune the numbers.
During the outage, we observed that one of our two caches consumed over 90GB of disk space (90% of what was available), while the second one was only using a few hundred KBs.
Using strace, we have traced down the system call that was responsible for this behavior. It turns out that, in an attempt to fix JDK-8168628, OpenJDK 8 Update 191 changed the behavior of RandomAccessFile::setLength on Linux-based systems from performing a fallocate instead of a ftruncate system call (patch diff).
This method is used by Chronicle Map to initialize the cache files on disk on startup. The change in behavior is subtle but important – where ftruncate merely updates the metadata for the file, while fallocate eagerly allocates backing disk space and zero-fills the file.
To understand the motivation of this change, JDK-8168628 describes the scenario where you are mapping a big file and eventually fail to lazily allocate the necessary disk space on subsequent access, causing a SIGBUS crash despite having "pre-allocated" the file with RandomAccessFile::setLength. In order to fix this crash, the assumption was that this method should eagerly allocate the requested disk space so that it would fail early.
This change had some unfortunate consequences. For starters, zero-ing a huge file is not a quick operation. But more importantly, quoting the latest comment from the bug thread: “it break[s] sparse files”… which is exactly what happened to us. The result of this change was that, when initializing the first cache, Java would now eagerly allocate 90 GB of backing disk. Since we had 100 GB available, this operation would succeed, although it would be a bit slow and result in a lot of unnecessary disk IO. However, when it came time to initialize the second cache, it would also try to eagerly allocate 90 GB of backing disk. Only this time, it would fail to do so as there is not enough disk space left.
For some reason, the resulting IOException was discarded and ignored. Perhaps the thought was that this was not necessarily a fatal problem, due to sparse files, or perhaps the hope was that disk space would eventually free up before they were really needed.
Whatever the logic, the application/library would happily proceed to mmap-ing the file, despite the error. However, since the first cache used up almost all the available disk space, shortly after, we ran out of backing disk and failed to allocate space on subsequent access, resulting in a SIGBUS fault. Ironically, this was exactly the situation described in JDK-8168628, and what the patch was trying to prevent in the first place.
The general consensus is that this patch was a bad idea and was fixing the wrong problem. In fact, it has already been reverted in JDK 11 and will hopefully make its way back to JDK 8 eventually.
Going Forward
Given that the incident was ultimately triggered by an automatic system update, it is natural to question whether that should have been enabled at all. As painful as this was, we still believe problems like these are a relatively rare occurrence and the benefits of automatic patching far outweigh the risk.
In a small team like ours, if everything is an emergency, then nothing really is. Perhaps in an ideal world, we would promise to review every security patch before applying them manually in a timely manner, the truth is we just don’t have that kind of resources to dedicate. Without the automatic update, we would likely fall behind on applying security patches, which would have far worse consequences.
That being said, we need to keep a closer eye on the upgrade process. In hindsight, the upgrade logs should have been one of the first things we checked. We will be adding this to our troubleshooting checklists, as well as setting up better notifications and monitoring around this to improve our situational awareness.
We will also work on improving our communications during incidents like this. While we have always had a status page setup, it was not prominently linked to from within the Skylight UI. This resulted in a pretty confusing experience during the outage, as customers would notice the missing data and assumed there was a problem on their end. To address this problem, we will be adding a live incident banner to the Skylight UI that shows the latest incident information right within the UI during an outage. This change should go live sometime this week, but hopefully you won’t see it anytime soon.
In the longer term, we will work on improving our architecture, such that we will be able to provision extra resources more fluidly during the recovery phase. This has always been on our wishlist, but it requires making some pretty significant changes to our architecture. Given that it would only make a difference in the rare outage scenarios, it was difficult to prioritize the work since we would rather be working on customer-facing features. However, we also understand that when it comes to winning your trust, reliability is just as important of a feature. We will do our best to strike the right balance here.
Once again, we are sorry for the trouble and would like to thank you for your patience during this incident. We will do better.
]]>
<![CDATA[Skylight Trends Reports, Now Outside of Your Inbox!]]>https://blog.skylight.io/trends-not-just-in-your-inbox-anymore/5cc9f70a70712a0017b35325Thu, 11 Oct 2018 15:16:51 GMTSkylight Trends Reports, Now Outside of Your Inbox!
Skylight’s latest update to Trends allows users to easily view & navigate through their historical trends data from within the Skylight UI.
Skylight Trends Reports, Now Outside of Your Inbox!
Seasoned Skylight users know that there is something special about opening up your email inbox on Monday mornings: why, getting to read your Skylight trends report, of course! 📬
But inboxes can be limiting—and overwhelming! That's why we're so excited about our latest update to Trends, which makes it easy to view your reports from week to week, without ever needing to look back at old emails.
Skylight Trends Reports, Now Outside of Your Inbox!
Skylight was designed to provide you with answers, not data. When we first created our Trends emails, we wanted to distill your performance data into a weekly report that would help you catch slowdowns before your customers.
This latest update to Trends provides you with the same reports that you know & love, in one easy-to-find place. No more digging through your inbox for your old Trends reports, or wishing that you hadn't deleted that Trends email from last month.
Skylight Trends Reports, Now Outside of Your Inbox!
Instead, historical Trends data for each of your apps will be available from your Skylight dashboard!
If you are already subscribed to our Trends emails, rest assured that you'll still get your Monday morning email, as usual. Just know that you can always find your reports in Skylight, too—just in case you ever need them again. 💌
Haven't tried out Skylight yet? Sign up for your 30-day free trial! Or refer a friend and you both get $50 in credit.
]]>
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| 0.536733 |
XNAT for Data Sharing: ConnectomeDB
Data sharing entails an investigator distributing his data, either openly, semi-openly, or in closed collaborations. Large NIH studies are required to share data and many smaller projects have realized the benefits of sharing. However, data sharing requires the use of an application that can give researchers control over multiple levels of access, and control which data is accessible by whom.
With the increasing prevalence of sharing, XNAT is being used more frequently in this context. The ConnectomeDB, which distributes more than 2 petabytes of data for the Human Connectome Project, is a prime example.
XNAT's access control system allows investigators to make their data openly accessible to users of their XNAT instance, accessible by request, or completely closed. Its support for anonymization and DICOM metadata review help ensure subject privacy and compliance with HIPAA regulations. In XNAT, investigators can harmonize their scan labeling scheme with commonly used terms. Finally, its extensible data model allows investigators to share a variety of non-imaging data and derived image data with their imaging studies.
Currently, XNAT is working with the Human Connectome Project and the Cancer Imaging Archive on each project's data sharing needs, and is the backbone of a publicly available imaging resource at XNAT Central.
Project Aims:
The Human Connectome Project was founded in 2011 as the charter project to create and share the largest dataset of brain imaging from healthy young adults to date. The HCP captured a complex imaging protocol across 3T MRI, 7T MRI and MEG data modalities. The protocol includes structural scans, resting-state and task functional scans, and diffusion scans. Moreover, the project needed to distribute data in unprocessed and preprocessed formats, and other types of data including task analysis and group average data.
In addition to the imaging data, the HCP performed an exhaustive set of behavioral and clinical data gathering, including information that needed to be restricted from the general public – either for potential identifiability (i.e. exact age, ethnicity, or family status) or sensitivity (i.e. alcohol and substance use, or family history of mental disorders).
Why use XNAT?
The HCP informatics team deployed two XNAT instances – one internal application ("IntraDB") to store and manage all incoming scans and data, and one external application ("ConnectomeDB") for pipeline processing and data sharing.
XNAT has native support for all of the data types that the HCP needed to distribute, and the extensibility of the front end and the permissions model allowed the HCP team to construct a heavily customized data-sharing UI. The permissions model applied "open access", "restricted access" and "sensitive access" levels of permissions to each user account, depending on what level of usage they had been approved for. This allowed ConnectomeDB to maintain IRB approval while distributing highly restricted and sensitive data to select investigators.
Additionally, XNAT's built-in project controls allowed for multiple phased releases of data as the project hit certain milestones – i.e. 500 subjects, 900 subjects, and 1200 subjects with completed imaging and processing.
By the final release of data, ConnectomeDB was storing and distributing nearly 2 petabytes of data. In order to facilitate the downloading of hundreds of gigabytes of data, this XNAT was integrated with an Aspera download server, which funnels extremely high-speed downloads outside of the http: protocol. HCP developers also built a custom download selector, allowing users to only select the imaging modalities and processing levels that were of interest to their research.
Who are the Primary Users?
IntraDB is used only by a small team of scan technicians, quality assurance, and data managers internal to the HCP.
ConnectomeDB has nearly 10,000 users at the open access permission level, and nearly 1,000 investigators that have been granted restricted access. As of November 2017, nearly 10 petabytes of data has been downloaded.
What Inherent Features of XNAT Have Been Most Useful?
By far, XNAT's extensibility should be considered as its most useful feature. Without that, managing a project of this scope and scale could never have been possible. Additionally, the trust in XNAT's security model enabled us to release data to a wide audience without breaching the project's IRB requirements.
$label.name
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__label__pos
| 0.821085 |
许可行,吴帅,周晓华.基于嵌入式系统的简易逻辑分析仪设计[J].国外电子测量技术,2017,36(7):77-81
基于嵌入式系统的简易逻辑分析仪设计
Design of simple logic analyzer based on embedded system
DOI：
中文关键词: 数字信号 逻辑分析仪 触发 多通道
英文关键词:digital signal logic analyzer attenuation triggering
基金项目:
作者单位
许可行 火箭军指挥学院 武汉 430012
吴帅 火箭军指挥学院 武汉 430012
周晓华 火箭军指挥学院 武汉 430012
AuthorInstitution
Xu Kexing Rocket Force Command College, Wuhan 430012, China
Wu Shuai Rocket Force Command College, Wuhan 430012, China
Zhou Xiaohua Rocket Force Command College, Wuhan 430012, China
摘要点击次数: 931
全文下载次数: 1150
中文摘要:
基于数字信号采集处理以及数字示波器存储显示原理，提出了一种简易逻辑分析仪制作方案。该系统主要由C8051F020与FPGA最小系统模块、ADC采集模块、信号衰减模块及TFT触摸显示模块组成。该设计采用单级、三级触发方式判断，可同时对8路信号进行采集、触发、存储及显示。经实验验证，该系统具有较高的测试速率、能实现多通道输入、可进行多级触发等优点。
英文摘要:
This paper presents a solution scheme to realize the simple logical analyzer based on digital signals processing and digital storage oscilloscope principle. The system is mainly composed of minimum system of C8051F020 and FPGA, ADC converting module, signal attenuation module and TFT Touch Screen. The design uses single stage and third stage trigger. Meanwhile, the system can collect 8 channels of analog signals, trigger and storage. The experiment indicates that system has the advantages ofhigh speed test, multichannel input, multi mode triggers.
查看全文 查看/发表评论 下载PDF阅读器
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| 0.581044 |
Are oats gluten free?
oats
Erin Dwyer - Research Dietitian, 02 March 2020
When we asked our instagram and Facebook audience what questions they would like answered, a common one was ‘What is the deal with oats?’. This is a great question as it is not 100% straight forward so let us clear it up....
But first, please remember, a low FODMAP diet is NOT a gluten free diet. When following a low FODMAP diet we are concerned about the ‘fermentable carbohydrates’, gluten is a protein so unless you have Coeliac Disease OR Non Coeliac Gluten sensitivity (NCGS) there is no need to worry about gluten. You can read more about this here
If you do have Coeliac Disease or NCGS, then oats are controversial. Gluten is the overarching name for the protein in wheat (gliadin), rye (secalin), barley (horedin) and oats (avenin). Currently you can test for each specific protein, except for avenin, the protein in oats. Therefore, the Australian Food Standard Code does not allow ‘Gluten Free’ labels on oat products in Australia. In Europe and the USA however, oats not contaminated with gluten-containing grains can be called Gluten Free.
What do we mean by not contaminated?
Sometimes referred to in international regulations, pure ‘non-contaminated' oats are oats that have not been processed in facilities with rye, barley or wheat.
Why can the USA and Europe call them gluten free?
In Australia, our testing for gluten is more specific than in other parts of the world, we test to 1-3 parts per million (ppm), whereas the USA and Europe test to only 20ppm, therefore we pick up the presence of gluten more often than other countries, so essentially Australia's rules are stricter.
Current Recommendations for those with Coeliac Disease
The current evidence suggests that most people with coeliac disease can tolerate uncontaminated or wheat free oats, however there are some will react to oats and it may or may not cause noticeable symptoms. Therefore, the recommendation from Coeliac Australia is if you would like to include oats in your gluten free diet then you should do so under medical supervision, with a gastroscopy and biopsy taken prior to commencing a daily intake of 50-70g oats for 3 months, then following with another gastroscopy with biopsy to assess your individual reaction (if any) to oats.(Rashid, M. et al., 2007)
If you are currently following Step 1 of the low FODMAP diet, be sure to check the app for low FODMAP serve sizes of oats - in their different forms (groats/rolled/quick) they do have different FODMAP content.
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Back to all articles
|
__label__pos
| 0.871656 |
Skip to content
KafkaConnectClient
Index > KafkaConnect > KafkaConnectClient
Auto-generated documentation for KafkaConnect type annotations stubs module mypy-boto3-kafkaconnect.
KafkaConnectClient
Type annotations and code completion for boto3.client("kafkaconnect"). boto3 documentation
Usage example
from boto3.session import Session
from mypy_boto3_kafkaconnect.client import KafkaConnectClient
def get_kafkaconnect_client() -> KafkaConnectClient:
return Session().client("kafkaconnect")
Exceptions
boto3 client exceptions are generated in runtime. This class provides code completion for boto3.client("kafkaconnect").exceptions structure.
Usage example
client = boto3.client("kafkaconnect")
try:
do_something(client)
except (
client.BadRequestException,
client.ClientError,
client.ConflictException,
client.ForbiddenException,
client.InternalServerErrorException,
client.NotFoundException,
client.ServiceUnavailableException,
client.TooManyRequestsException,
client.UnauthorizedException,
) as e:
print(e)
Type checking example
from mypy_boto3_kafkaconnect.client import Exceptions
def handle_error(exc: Exceptions.BadRequestException) -> None:
...
Methods
can_paginate
Check if an operation can be paginated.
Type annotations and code completion for boto3.client("kafkaconnect").can_paginate method. boto3 documentation
Method definition
def can_paginate(
self,
operation_name: str,
) -> bool:
...
close
Closes underlying endpoint connections.
Type annotations and code completion for boto3.client("kafkaconnect").close method. boto3 documentation
Method definition
def close(
self,
) -> None:
...
create_connector
Creates a connector using the specified properties.
Type annotations and code completion for boto3.client("kafkaconnect").create_connector method. boto3 documentation
Method definition
def create_connector(
self,
*,
capacity: CapacityTypeDef, # (1)
connectorConfiguration: Mapping[str, str],
connectorName: str,
kafkaCluster: KafkaClusterTypeDef, # (2)
kafkaClusterClientAuthentication: KafkaClusterClientAuthenticationTypeDef, # (3)
kafkaClusterEncryptionInTransit: KafkaClusterEncryptionInTransitTypeDef, # (4)
kafkaConnectVersion: str,
plugins: Sequence[PluginTypeDef], # (5)
serviceExecutionRoleArn: str,
connectorDescription: str = ...,
logDelivery: LogDeliveryTypeDef = ..., # (6)
workerConfiguration: WorkerConfigurationTypeDef = ..., # (7)
) -> CreateConnectorResponseTypeDef: # (8)
...
1. See CapacityTypeDef
2. See KafkaClusterTypeDef
3. See KafkaClusterClientAuthenticationTypeDef
4. See KafkaClusterEncryptionInTransitTypeDef
5. See PluginTypeDef
6. See LogDeliveryTypeDef
7. See WorkerConfigurationTypeDef
8. See CreateConnectorResponseTypeDef
Usage example with kwargs
kwargs: CreateConnectorRequestRequestTypeDef = { # (1)
"capacity": ...,
"connectorConfiguration": ...,
"connectorName": ...,
"kafkaCluster": ...,
"kafkaClusterClientAuthentication": ...,
"kafkaClusterEncryptionInTransit": ...,
"kafkaConnectVersion": ...,
"plugins": ...,
"serviceExecutionRoleArn": ...,
}
parent.create_connector(**kwargs)
1. See CreateConnectorRequestRequestTypeDef
create_custom_plugin
Creates a custom plugin using the specified properties.
Type annotations and code completion for boto3.client("kafkaconnect").create_custom_plugin method. boto3 documentation
Method definition
def create_custom_plugin(
self,
*,
contentType: CustomPluginContentTypeType, # (1)
location: CustomPluginLocationTypeDef, # (2)
name: str,
description: str = ...,
) -> CreateCustomPluginResponseTypeDef: # (3)
...
1. See CustomPluginContentTypeType
2. See CustomPluginLocationTypeDef
3. See CreateCustomPluginResponseTypeDef
Usage example with kwargs
kwargs: CreateCustomPluginRequestRequestTypeDef = { # (1)
"contentType": ...,
"location": ...,
"name": ...,
}
parent.create_custom_plugin(**kwargs)
1. See CreateCustomPluginRequestRequestTypeDef
create_worker_configuration
Creates a worker configuration using the specified properties.
Type annotations and code completion for boto3.client("kafkaconnect").create_worker_configuration method. boto3 documentation
Method definition
def create_worker_configuration(
self,
*,
name: str,
propertiesFileContent: str,
description: str = ...,
) -> CreateWorkerConfigurationResponseTypeDef: # (1)
...
1. See CreateWorkerConfigurationResponseTypeDef
Usage example with kwargs
kwargs: CreateWorkerConfigurationRequestRequestTypeDef = { # (1)
"name": ...,
"propertiesFileContent": ...,
}
parent.create_worker_configuration(**kwargs)
1. See CreateWorkerConfigurationRequestRequestTypeDef
delete_connector
Deletes the specified connector.
Type annotations and code completion for boto3.client("kafkaconnect").delete_connector method. boto3 documentation
Method definition
def delete_connector(
self,
*,
connectorArn: str,
currentVersion: str = ...,
) -> DeleteConnectorResponseTypeDef: # (1)
...
1. See DeleteConnectorResponseTypeDef
Usage example with kwargs
kwargs: DeleteConnectorRequestRequestTypeDef = { # (1)
"connectorArn": ...,
}
parent.delete_connector(**kwargs)
1. See DeleteConnectorRequestRequestTypeDef
delete_custom_plugin
Deletes a custom plugin.
Type annotations and code completion for boto3.client("kafkaconnect").delete_custom_plugin method. boto3 documentation
Method definition
def delete_custom_plugin(
self,
*,
customPluginArn: str,
) -> DeleteCustomPluginResponseTypeDef: # (1)
...
1. See DeleteCustomPluginResponseTypeDef
Usage example with kwargs
kwargs: DeleteCustomPluginRequestRequestTypeDef = { # (1)
"customPluginArn": ...,
}
parent.delete_custom_plugin(**kwargs)
1. See DeleteCustomPluginRequestRequestTypeDef
describe_connector
Returns summary information about the connector.
Type annotations and code completion for boto3.client("kafkaconnect").describe_connector method. boto3 documentation
Method definition
def describe_connector(
self,
*,
connectorArn: str,
) -> DescribeConnectorResponseTypeDef: # (1)
...
1. See DescribeConnectorResponseTypeDef
Usage example with kwargs
kwargs: DescribeConnectorRequestRequestTypeDef = { # (1)
"connectorArn": ...,
}
parent.describe_connector(**kwargs)
1. See DescribeConnectorRequestRequestTypeDef
describe_custom_plugin
A summary description of the custom plugin.
Type annotations and code completion for boto3.client("kafkaconnect").describe_custom_plugin method. boto3 documentation
Method definition
def describe_custom_plugin(
self,
*,
customPluginArn: str,
) -> DescribeCustomPluginResponseTypeDef: # (1)
...
1. See DescribeCustomPluginResponseTypeDef
Usage example with kwargs
kwargs: DescribeCustomPluginRequestRequestTypeDef = { # (1)
"customPluginArn": ...,
}
parent.describe_custom_plugin(**kwargs)
1. See DescribeCustomPluginRequestRequestTypeDef
describe_worker_configuration
Returns information about a worker configuration.
Type annotations and code completion for boto3.client("kafkaconnect").describe_worker_configuration method. boto3 documentation
Method definition
def describe_worker_configuration(
self,
*,
workerConfigurationArn: str,
) -> DescribeWorkerConfigurationResponseTypeDef: # (1)
...
1. See DescribeWorkerConfigurationResponseTypeDef
Usage example with kwargs
kwargs: DescribeWorkerConfigurationRequestRequestTypeDef = { # (1)
"workerConfigurationArn": ...,
}
parent.describe_worker_configuration(**kwargs)
1. See DescribeWorkerConfigurationRequestRequestTypeDef
generate_presigned_url
Generate a presigned url given a client, its method, and arguments.
Type annotations and code completion for boto3.client("kafkaconnect").generate_presigned_url method. boto3 documentation
Method definition
def generate_presigned_url(
self,
ClientMethod: str,
Params: Mapping[str, Any] = ...,
ExpiresIn: int = 3600,
HttpMethod: str = ...,
) -> str:
...
list_connectors
Returns a list of all the connectors in this account and Region.
Type annotations and code completion for boto3.client("kafkaconnect").list_connectors method. boto3 documentation
Method definition
def list_connectors(
self,
*,
connectorNamePrefix: str = ...,
maxResults: int = ...,
nextToken: str = ...,
) -> ListConnectorsResponseTypeDef: # (1)
...
1. See ListConnectorsResponseTypeDef
Usage example with kwargs
kwargs: ListConnectorsRequestRequestTypeDef = { # (1)
"connectorNamePrefix": ...,
}
parent.list_connectors(**kwargs)
1. See ListConnectorsRequestRequestTypeDef
list_custom_plugins
Returns a list of all of the custom plugins in this account and Region.
Type annotations and code completion for boto3.client("kafkaconnect").list_custom_plugins method. boto3 documentation
Method definition
def list_custom_plugins(
self,
*,
maxResults: int = ...,
nextToken: str = ...,
) -> ListCustomPluginsResponseTypeDef: # (1)
...
1. See ListCustomPluginsResponseTypeDef
Usage example with kwargs
kwargs: ListCustomPluginsRequestRequestTypeDef = { # (1)
"maxResults": ...,
}
parent.list_custom_plugins(**kwargs)
1. See ListCustomPluginsRequestRequestTypeDef
list_worker_configurations
Returns a list of all of the worker configurations in this account and Region.
Type annotations and code completion for boto3.client("kafkaconnect").list_worker_configurations method. boto3 documentation
Method definition
def list_worker_configurations(
self,
*,
maxResults: int = ...,
nextToken: str = ...,
) -> ListWorkerConfigurationsResponseTypeDef: # (1)
...
1. See ListWorkerConfigurationsResponseTypeDef
Usage example with kwargs
kwargs: ListWorkerConfigurationsRequestRequestTypeDef = { # (1)
"maxResults": ...,
}
parent.list_worker_configurations(**kwargs)
1. See ListWorkerConfigurationsRequestRequestTypeDef
update_connector
Updates the specified connector.
Type annotations and code completion for boto3.client("kafkaconnect").update_connector method. boto3 documentation
Method definition
def update_connector(
self,
*,
capacity: CapacityUpdateTypeDef, # (1)
connectorArn: str,
currentVersion: str,
) -> UpdateConnectorResponseTypeDef: # (2)
...
1. See CapacityUpdateTypeDef
2. See UpdateConnectorResponseTypeDef
Usage example with kwargs
kwargs: UpdateConnectorRequestRequestTypeDef = { # (1)
"capacity": ...,
"connectorArn": ...,
"currentVersion": ...,
}
parent.update_connector(**kwargs)
1. See UpdateConnectorRequestRequestTypeDef
get_paginator
Type annotations and code completion for boto3.client("kafkaconnect").get_paginator method with overloads.
|
__label__pos
| 0.842396 |
YUI recommends YUI 3.
YUI 2 has been deprecated since 2011. This site acts as an archive for files and documentation.
Yahoo! UI Library
TreeView Widget 2.7.0
Yahoo! UI Library > treeview > Node.js (source view)
Search:
Filters
(function () {
var Dom = YAHOO.util.Dom,
Lang = YAHOO.lang,
Event = YAHOO.util.Event;
/**
* The base class for all tree nodes. The node's presentation and behavior in
* response to mouse events is handled in Node subclasses.
* @namespace YAHOO.widget
* @class Node
* @uses YAHOO.util.EventProvider
* @param oData {object} a string or object containing the data that will
* be used to render this node, and any custom attributes that should be
* stored with the node (which is available in noderef.data).
* All values in oData will be used to set equally named properties in the node
* as long as the node does have such properties, they are not undefined, private or functions,
* the rest of the values will be stored in noderef.data
* @param oParent {Node} this node's parent node
* @param expanded {boolean} the initial expanded/collapsed state (deprecated, use oData.expanded)
* @constructor
*/
YAHOO.widget.Node = function(oData, oParent, expanded) {
if (oData) { this.init(oData, oParent, expanded); }
};
YAHOO.widget.Node.prototype = {
/**
* The index for this instance obtained from global counter in YAHOO.widget.TreeView.
* @property index
* @type int
*/
index: 0,
/**
* This node's child node collection.
* @property children
* @type Node[]
*/
children: null,
/**
* Tree instance this node is part of
* @property tree
* @type TreeView
*/
tree: null,
/**
* The data linked to this node. This can be any object or primitive
* value, and the data can be used in getNodeHtml().
* @property data
* @type object
*/
data: null,
/**
* Parent node
* @property parent
* @type Node
*/
parent: null,
/**
* The depth of this node. We start at -1 for the root node.
* @property depth
* @type int
*/
depth: -1,
/**
* The node's expanded/collapsed state
* @property expanded
* @type boolean
*/
expanded: false,
/**
* Can multiple children be expanded at once?
* @property multiExpand
* @type boolean
*/
multiExpand: true,
/**
* Should we render children for a collapsed node? It is possible that the
* implementer will want to render the hidden data... @todo verify that we
* need this, and implement it if we do.
* @property renderHidden
* @type boolean
*/
renderHidden: false,
/**
* This flag is set to true when the html is generated for this node's
* children, and set to false when new children are added.
* @property childrenRendered
* @type boolean
*/
childrenRendered: false,
/**
* Dynamically loaded nodes only fetch the data the first time they are
* expanded. This flag is set to true once the data has been fetched.
* @property dynamicLoadComplete
* @type boolean
*/
dynamicLoadComplete: false,
/**
* This node's previous sibling
* @property previousSibling
* @type Node
*/
previousSibling: null,
/**
* This node's next sibling
* @property nextSibling
* @type Node
*/
nextSibling: null,
/**
* We can set the node up to call an external method to get the child
* data dynamically.
* @property _dynLoad
* @type boolean
* @private
*/
_dynLoad: false,
/**
* Function to execute when we need to get this node's child data.
* @property dataLoader
* @type function
*/
dataLoader: null,
/**
* This is true for dynamically loading nodes while waiting for the
* callback to return.
* @property isLoading
* @type boolean
*/
isLoading: false,
/**
* The toggle/branch icon will not show if this is set to false. This
* could be useful if the implementer wants to have the child contain
* extra info about the parent, rather than an actual node.
* @property hasIcon
* @type boolean
*/
hasIcon: true,
/**
* Used to configure what happens when a dynamic load node is expanded
* and we discover that it does not have children. By default, it is
* treated as if it still could have children (plus/minus icon). Set
* iconMode to have it display like a leaf node instead.
* @property iconMode
* @type int
*/
iconMode: 0,
/**
* Specifies whether or not the content area of the node should be allowed
* to wrap.
* @property nowrap
* @type boolean
* @default false
*/
nowrap: false,
/**
* If true, the node will alway be rendered as a leaf node. This can be
* used to override the presentation when dynamically loading the entire
* tree. Setting this to true also disables the dynamic load call for the
* node.
* @property isLeaf
* @type boolean
* @default false
*/
isLeaf: false,
/**
* The CSS class for the html content container. Defaults to ygtvhtml, but
* can be overridden to provide a custom presentation for a specific node.
* @property contentStyle
* @type string
*/
contentStyle: "",
/**
* The generated id that will contain the data passed in by the implementer.
* @property contentElId
* @type string
*/
contentElId: null,
/**
* Enables node highlighting. If true, the node can be highlighted and/or propagate highlighting
* @property enableHighlight
* @type boolean
* @default true
*/
enableHighlight: true,
/**
* Stores the highlight state. Can be any of:
* <ul>
* <li>0 - not highlighted</li>
* <li>1 - highlighted</li>
* <li>2 - some children highlighted</li>
* </ul>
* @property highlightState
* @type integer
* @default 0
*/
highlightState: 0,
/**
* Tells whether highlighting will be propagated up to the parents of the clicked node
* @property propagateHighlightUp
* @type boolean
* @default false
*/
propagateHighlightUp: false,
/**
* Tells whether highlighting will be propagated down to the children of the clicked node
* @property propagateHighlightDown
* @type boolean
* @default false
*/
propagateHighlightDown: false,
/**
* User-defined className to be added to the Node
* @property className
* @type string
* @default null
*/
className: null,
/**
* The node type
* @property _type
* @private
* @type string
* @default "Node"
*/
_type: "Node",
/*
spacerPath: "http://us.i1.yimg.com/us.yimg.com/i/space.gif",
expandedText: "Expanded",
collapsedText: "Collapsed",
loadingText: "Loading",
*/
/**
* Initializes this node, gets some of the properties from the parent
* @method init
* @param oData {object} a string or object containing the data that will
* be used to render this node
* @param oParent {Node} this node's parent node
* @param expanded {boolean} the initial expanded/collapsed state
*/
init: function(oData, oParent, expanded) {
this.data = {};
this.children = [];
this.index = YAHOO.widget.TreeView.nodeCount;
++YAHOO.widget.TreeView.nodeCount;
this.contentElId = "ygtvcontentel" + this.index;
if (Lang.isObject(oData)) {
for (var property in oData) {
if (oData.hasOwnProperty(property)) {
if (property.charAt(0) != '_' && !Lang.isUndefined(this[property]) && !Lang.isFunction(this[property]) ) {
this[property] = oData[property];
} else {
this.data[property] = oData[property];
}
}
}
}
if (!Lang.isUndefined(expanded) ) { this.expanded = expanded; }
this.logger = new YAHOO.widget.LogWriter(this.toString());
/**
* The parentChange event is fired when a parent element is applied
* to the node. This is useful if you need to apply tree-level
* properties to a tree that need to happen if a node is moved from
* one tree to another.
*
* @event parentChange
* @type CustomEvent
*/
this.createEvent("parentChange", this);
// oParent should never be null except when we create the root node.
if (oParent) {
oParent.appendChild(this);
}
},
/**
* Certain properties for the node cannot be set until the parent
* is known. This is called after the node is inserted into a tree.
* the parent is also applied to this node's children in order to
* make it possible to move a branch from one tree to another.
* @method applyParent
* @param {Node} parentNode this node's parent node
* @return {boolean} true if the application was successful
*/
applyParent: function(parentNode) {
if (!parentNode) {
return false;
}
this.tree = parentNode.tree;
this.parent = parentNode;
this.depth = parentNode.depth + 1;
// @todo why was this put here. This causes new nodes added at the
// root level to lose the menu behavior.
// if (! this.multiExpand) {
// this.multiExpand = parentNode.multiExpand;
// }
this.tree.regNode(this);
parentNode.childrenRendered = false;
// cascade update existing children
for (var i=0, len=this.children.length;i<len;++i) {
this.children[i].applyParent(this);
}
this.fireEvent("parentChange");
return true;
},
/**
* Appends a node to the child collection.
* @method appendChild
* @param childNode {Node} the new node
* @return {Node} the child node
* @private
*/
appendChild: function(childNode) {
if (this.hasChildren()) {
var sib = this.children[this.children.length - 1];
sib.nextSibling = childNode;
childNode.previousSibling = sib;
}
this.children[this.children.length] = childNode;
childNode.applyParent(this);
// part of the IE display issue workaround. If child nodes
// are added after the initial render, and the node was
// instantiated with expanded = true, we need to show the
// children div now that the node has a child.
if (this.childrenRendered && this.expanded) {
this.getChildrenEl().style.display = "";
}
return childNode;
},
/**
* Appends this node to the supplied node's child collection
* @method appendTo
* @param parentNode {Node} the node to append to.
* @return {Node} The appended node
*/
appendTo: function(parentNode) {
return parentNode.appendChild(this);
},
/**
* Inserts this node before this supplied node
* @method insertBefore
* @param node {Node} the node to insert this node before
* @return {Node} the inserted node
*/
insertBefore: function(node) {
this.logger.log("insertBefore: " + node);
var p = node.parent;
if (p) {
if (this.tree) {
this.tree.popNode(this);
}
var refIndex = node.isChildOf(p);
//this.logger.log(refIndex);
p.children.splice(refIndex, 0, this);
if (node.previousSibling) {
node.previousSibling.nextSibling = this;
}
this.previousSibling = node.previousSibling;
this.nextSibling = node;
node.previousSibling = this;
this.applyParent(p);
}
return this;
},
/**
* Inserts this node after the supplied node
* @method insertAfter
* @param node {Node} the node to insert after
* @return {Node} the inserted node
*/
insertAfter: function(node) {
this.logger.log("insertAfter: " + node);
var p = node.parent;
if (p) {
if (this.tree) {
this.tree.popNode(this);
}
var refIndex = node.isChildOf(p);
this.logger.log(refIndex);
if (!node.nextSibling) {
this.nextSibling = null;
return this.appendTo(p);
}
p.children.splice(refIndex + 1, 0, this);
node.nextSibling.previousSibling = this;
this.previousSibling = node;
this.nextSibling = node.nextSibling;
node.nextSibling = this;
this.applyParent(p);
}
return this;
},
/**
* Returns true if the Node is a child of supplied Node
* @method isChildOf
* @param parentNode {Node} the Node to check
* @return {boolean} The node index if this Node is a child of
* supplied Node, else -1.
* @private
*/
isChildOf: function(parentNode) {
if (parentNode && parentNode.children) {
for (var i=0, len=parentNode.children.length; i<len ; ++i) {
if (parentNode.children[i] === this) {
return i;
}
}
}
return -1;
},
/**
* Returns a node array of this node's siblings, null if none.
* @method getSiblings
* @return Node[]
*/
getSiblings: function() {
var sib = this.parent.children.slice(0);
for (var i=0;i < sib.length && sib[i] != this;i++) {}
sib.splice(i,1);
if (sib.length) { return sib; }
return null;
},
/**
* Shows this node's children
* @method showChildren
*/
showChildren: function() {
if (!this.tree.animateExpand(this.getChildrenEl(), this)) {
if (this.hasChildren()) {
this.getChildrenEl().style.display = "";
}
}
},
/**
* Hides this node's children
* @method hideChildren
*/
hideChildren: function() {
this.logger.log("hiding " + this.index);
if (!this.tree.animateCollapse(this.getChildrenEl(), this)) {
this.getChildrenEl().style.display = "none";
}
},
/**
* Returns the id for this node's container div
* @method getElId
* @return {string} the element id
*/
getElId: function() {
return "ygtv" + this.index;
},
/**
* Returns the id for this node's children div
* @method getChildrenElId
* @return {string} the element id for this node's children div
*/
getChildrenElId: function() {
return "ygtvc" + this.index;
},
/**
* Returns the id for this node's toggle element
* @method getToggleElId
* @return {string} the toggel element id
*/
getToggleElId: function() {
return "ygtvt" + this.index;
},
/*
* Returns the id for this node's spacer image. The spacer is positioned
* over the toggle and provides feedback for screen readers.
* @method getSpacerId
* @return {string} the id for the spacer image
*/
/*
getSpacerId: function() {
return "ygtvspacer" + this.index;
},
*/
/**
* Returns this node's container html element
* @method getEl
* @return {HTMLElement} the container html element
*/
getEl: function() {
return Dom.get(this.getElId());
},
/**
* Returns the div that was generated for this node's children
* @method getChildrenEl
* @return {HTMLElement} this node's children div
*/
getChildrenEl: function() {
return Dom.get(this.getChildrenElId());
},
/**
* Returns the element that is being used for this node's toggle.
* @method getToggleEl
* @return {HTMLElement} this node's toggle html element
*/
getToggleEl: function() {
return Dom.get(this.getToggleElId());
},
/**
* Returns the outer html element for this node's content
* @method getContentEl
* @return {HTMLElement} the element
*/
getContentEl: function() {
return Dom.get(this.contentElId);
},
/*
* Returns the element that is being used for this node's spacer.
* @method getSpacer
* @return {HTMLElement} this node's spacer html element
*/
/*
getSpacer: function() {
return document.getElementById( this.getSpacerId() ) || {};
},
*/
/*
getStateText: function() {
if (this.isLoading) {
return this.loadingText;
} else if (this.hasChildren(true)) {
if (this.expanded) {
return this.expandedText;
} else {
return this.collapsedText;
}
} else {
return "";
}
},
*/
/**
* Hides this nodes children (creating them if necessary), changes the toggle style.
* @method collapse
*/
collapse: function() {
// Only collapse if currently expanded
if (!this.expanded) { return; }
// fire the collapse event handler
var ret = this.tree.onCollapse(this);
if (false === ret) {
this.logger.log("Collapse was stopped by the abstract onCollapse");
return;
}
ret = this.tree.fireEvent("collapse", this);
if (false === ret) {
this.logger.log("Collapse was stopped by a custom event handler");
return;
}
if (!this.getEl()) {
this.expanded = false;
} else {
// hide the child div
this.hideChildren();
this.expanded = false;
this.updateIcon();
}
// this.getSpacer().title = this.getStateText();
ret = this.tree.fireEvent("collapseComplete", this);
},
/**
* Shows this nodes children (creating them if necessary), changes the
* toggle style, and collapses its siblings if multiExpand is not set.
* @method expand
*/
expand: function(lazySource) {
// Only expand if currently collapsed.
if (this.expanded && !lazySource) {
return;
}
var ret = true;
// When returning from the lazy load handler, expand is called again
// in order to render the new children. The "expand" event already
// fired before fething the new data, so we need to skip it now.
if (!lazySource) {
// fire the expand event handler
ret = this.tree.onExpand(this);
if (false === ret) {
this.logger.log("Expand was stopped by the abstract onExpand");
return;
}
ret = this.tree.fireEvent("expand", this);
}
if (false === ret) {
this.logger.log("Expand was stopped by the custom event handler");
return;
}
if (!this.getEl()) {
this.expanded = true;
return;
}
if (!this.childrenRendered) {
this.logger.log("children not rendered yet");
this.getChildrenEl().innerHTML = this.renderChildren();
} else {
this.logger.log("children already rendered");
}
this.expanded = true;
this.updateIcon();
// this.getSpacer().title = this.getStateText();
// We do an extra check for children here because the lazy
// load feature can expose nodes that have no children.
// if (!this.hasChildren()) {
if (this.isLoading) {
this.expanded = false;
return;
}
if (! this.multiExpand) {
var sibs = this.getSiblings();
for (var i=0; sibs && i<sibs.length; ++i) {
if (sibs[i] != this && sibs[i].expanded) {
sibs[i].collapse();
}
}
}
this.showChildren();
ret = this.tree.fireEvent("expandComplete", this);
},
updateIcon: function() {
if (this.hasIcon) {
var el = this.getToggleEl();
if (el) {
el.className = el.className.replace(/\bygtv(([tl][pmn]h?)|(loading))\b/gi,this.getStyle());
}
}
},
/**
* Returns the css style name for the toggle
* @method getStyle
* @return {string} the css class for this node's toggle
*/
getStyle: function() {
// this.logger.log("No children, " + " isDyanmic: " + this.isDynamic() + " expanded: " + this.expanded);
if (this.isLoading) {
this.logger.log("returning the loading icon");
return "ygtvloading";
} else {
// location top or bottom, middle nodes also get the top style
var loc = (this.nextSibling) ? "t" : "l";
// type p=plus(expand), m=minus(collapase), n=none(no children)
var type = "n";
if (this.hasChildren(true) || (this.isDynamic() && !this.getIconMode())) {
// if (this.hasChildren(true)) {
type = (this.expanded) ? "m" : "p";
}
// this.logger.log("ygtv" + loc + type);
return "ygtv" + loc + type;
}
},
/**
* Returns the hover style for the icon
* @return {string} the css class hover state
* @method getHoverStyle
*/
getHoverStyle: function() {
var s = this.getStyle();
if (this.hasChildren(true) && !this.isLoading) {
s += "h";
}
return s;
},
/**
* Recursively expands all of this node's children.
* @method expandAll
*/
expandAll: function() {
var l = this.children.length;
for (var i=0;i<l;++i) {
var c = this.children[i];
if (c.isDynamic()) {
this.logger.log("Not supported (lazy load + expand all)");
break;
} else if (! c.multiExpand) {
this.logger.log("Not supported (no multi-expand + expand all)");
break;
} else {
c.expand();
c.expandAll();
}
}
},
/**
* Recursively collapses all of this node's children.
* @method collapseAll
*/
collapseAll: function() {
for (var i=0;i<this.children.length;++i) {
this.children[i].collapse();
this.children[i].collapseAll();
}
},
/**
* Configures this node for dynamically obtaining the child data
* when the node is first expanded. Calling it without the callback
* will turn off dynamic load for the node.
* @method setDynamicLoad
* @param fmDataLoader {function} the function that will be used to get the data.
* @param iconMode {int} configures the icon that is displayed when a dynamic
* load node is expanded the first time without children. By default, the
* "collapse" icon will be used. If set to 1, the leaf node icon will be
* displayed.
*/
setDynamicLoad: function(fnDataLoader, iconMode) {
if (fnDataLoader) {
this.dataLoader = fnDataLoader;
this._dynLoad = true;
} else {
this.dataLoader = null;
this._dynLoad = false;
}
if (iconMode) {
this.iconMode = iconMode;
}
},
/**
* Evaluates if this node is the root node of the tree
* @method isRoot
* @return {boolean} true if this is the root node
*/
isRoot: function() {
return (this == this.tree.root);
},
/**
* Evaluates if this node's children should be loaded dynamically. Looks for
* the property both in this instance and the root node. If the tree is
* defined to load all children dynamically, the data callback function is
* defined in the root node
* @method isDynamic
* @return {boolean} true if this node's children are to be loaded dynamically
*/
isDynamic: function() {
if (this.isLeaf) {
return false;
} else {
return (!this.isRoot() && (this._dynLoad || this.tree.root._dynLoad));
// this.logger.log("isDynamic: " + lazy);
// return lazy;
}
},
/**
* Returns the current icon mode. This refers to the way childless dynamic
* load nodes appear (this comes into play only after the initial dynamic
* load request produced no children).
* @method getIconMode
* @return {int} 0 for collapse style, 1 for leaf node style
*/
getIconMode: function() {
return (this.iconMode || this.tree.root.iconMode);
},
/**
* Checks if this node has children. If this node is lazy-loading and the
* children have not been rendered, we do not know whether or not there
* are actual children. In most cases, we need to assume that there are
* children (for instance, the toggle needs to show the expandable
* presentation state). In other times we want to know if there are rendered
* children. For the latter, "checkForLazyLoad" should be false.
* @method hasChildren
* @param checkForLazyLoad {boolean} should we check for unloaded children?
* @return {boolean} true if this has children or if it might and we are
* checking for this condition.
*/
hasChildren: function(checkForLazyLoad) {
if (this.isLeaf) {
return false;
} else {
return ( this.children.length > 0 ||
(checkForLazyLoad && this.isDynamic() && !this.dynamicLoadComplete) );
}
},
/**
* Expands if node is collapsed, collapses otherwise.
* @method toggle
*/
toggle: function() {
if (!this.tree.locked && ( this.hasChildren(true) || this.isDynamic()) ) {
if (this.expanded) { this.collapse(); } else { this.expand(); }
}
},
/**
* Returns the markup for this node and its children.
* @method getHtml
* @return {string} the markup for this node and its expanded children.
*/
getHtml: function() {
this.childrenRendered = false;
return ['<div class="ygtvitem" id="' , this.getElId() , '">' ,this.getNodeHtml() , this.getChildrenHtml() ,'</div>'].join("");
},
/**
* Called when first rendering the tree. We always build the div that will
* contain this nodes children, but we don't render the children themselves
* unless this node is expanded.
* @method getChildrenHtml
* @return {string} the children container div html and any expanded children
* @private
*/
getChildrenHtml: function() {
var sb = [];
sb[sb.length] = '<div class="ygtvchildren" id="' + this.getChildrenElId() + '"';
// This is a workaround for an IE rendering issue, the child div has layout
// in IE, creating extra space if a leaf node is created with the expanded
// property set to true.
if (!this.expanded || !this.hasChildren()) {
sb[sb.length] = ' style="display:none;"';
}
sb[sb.length] = '>';
// this.logger.log(["index", this.index,
// "hasChildren", this.hasChildren(true),
// "expanded", this.expanded,
// "renderHidden", this.renderHidden,
// "isDynamic", this.isDynamic()]);
// Don't render the actual child node HTML unless this node is expanded.
if ( (this.hasChildren(true) && this.expanded) ||
(this.renderHidden && !this.isDynamic()) ) {
sb[sb.length] = this.renderChildren();
}
sb[sb.length] = '</div>';
return sb.join("");
},
/**
* Generates the markup for the child nodes. This is not done until the node
* is expanded.
* @method renderChildren
* @return {string} the html for this node's children
* @private
*/
renderChildren: function() {
this.logger.log("rendering children for " + this.index);
var node = this;
if (this.isDynamic() && !this.dynamicLoadComplete) {
this.isLoading = true;
this.tree.locked = true;
if (this.dataLoader) {
this.logger.log("Using dynamic loader defined for this node");
setTimeout(
function() {
node.dataLoader(node,
function() {
node.loadComplete();
});
}, 10);
} else if (this.tree.root.dataLoader) {
this.logger.log("Using the tree-level dynamic loader");
setTimeout(
function() {
node.tree.root.dataLoader(node,
function() {
node.loadComplete();
});
}, 10);
} else {
this.logger.log("no loader found");
return "Error: data loader not found or not specified.";
}
return "";
} else {
return this.completeRender();
}
},
/**
* Called when we know we have all the child data.
* @method completeRender
* @return {string} children html
*/
completeRender: function() {
this.logger.log("completeRender: " + this.index + ", # of children: " + this.children.length);
var sb = [];
for (var i=0; i < this.children.length; ++i) {
// this.children[i].childrenRendered = false;
sb[sb.length] = this.children[i].getHtml();
}
this.childrenRendered = true;
return sb.join("");
},
/**
* Load complete is the callback function we pass to the data provider
* in dynamic load situations.
* @method loadComplete
*/
loadComplete: function() {
this.logger.log(this.index + " loadComplete, children: " + this.children.length);
this.getChildrenEl().innerHTML = this.completeRender();
this.dynamicLoadComplete = true;
this.isLoading = false;
this.expand(true);
this.tree.locked = false;
},
/**
* Returns this node's ancestor at the specified depth.
* @method getAncestor
* @param {int} depth the depth of the ancestor.
* @return {Node} the ancestor
*/
getAncestor: function(depth) {
if (depth >= this.depth || depth < 0) {
this.logger.log("illegal getAncestor depth: " + depth);
return null;
}
var p = this.parent;
while (p.depth > depth) {
p = p.parent;
}
return p;
},
/**
* Returns the css class for the spacer at the specified depth for
* this node. If this node's ancestor at the specified depth
* has a next sibling the presentation is different than if it
* does not have a next sibling
* @method getDepthStyle
* @param {int} depth the depth of the ancestor.
* @return {string} the css class for the spacer
*/
getDepthStyle: function(depth) {
return (this.getAncestor(depth).nextSibling) ?
"ygtvdepthcell" : "ygtvblankdepthcell";
},
/**
* Get the markup for the node. This may be overrided so that we can
* support different types of nodes.
* @method getNodeHtml
* @return {string} The HTML that will render this node.
*/
getNodeHtml: function() {
this.logger.log("Generating html");
var sb = [];
sb[sb.length] = '<table id="ygtvtableel' + this.index + '"border="0" cellpadding="0" cellspacing="0" class="ygtvtable ygtvdepth' + this.depth;
if (this.enableHighlight) {
sb[sb.length] = ' ygtv-highlight' + this.highlightState;
}
if (this.className) {
sb[sb.length] = ' ' + this.className;
}
sb[sb.length] = '"><tr class="ygtvrow">';
for (var i=0;i<this.depth;++i) {
sb[sb.length] = '<td class="ygtvcell ' + this.getDepthStyle(i) + '"><div class="ygtvspacer"></div></td>';
}
if (this.hasIcon) {
sb[sb.length] = '<td id="' + this.getToggleElId();
sb[sb.length] = '" class="ygtvcell ';
sb[sb.length] = this.getStyle() ;
sb[sb.length] = '"><a href="#" class="ygtvspacer"> </a></td>';
}
sb[sb.length] = '<td id="' + this.contentElId;
sb[sb.length] = '" class="ygtvcell ';
sb[sb.length] = this.contentStyle + ' ygtvcontent" ';
sb[sb.length] = (this.nowrap) ? ' nowrap="nowrap" ' : '';
sb[sb.length] = ' >';
sb[sb.length] = this.getContentHtml();
sb[sb.length] = '</td></tr></table>';
return sb.join("");
},
/**
* Get the markup for the contents of the node. This is designed to be overrided so that we can
* support different types of nodes.
* @method getContentHtml
* @return {string} The HTML that will render the content of this node.
*/
getContentHtml: function () {
return "";
},
/**
* Regenerates the html for this node and its children. To be used when the
* node is expanded and new children have been added.
* @method refresh
*/
refresh: function() {
// this.loadComplete();
this.getChildrenEl().innerHTML = this.completeRender();
if (this.hasIcon) {
var el = this.getToggleEl();
if (el) {
el.className = el.className.replace(/\bygtv[lt][nmp]h*\b/gi,this.getStyle());
}
}
},
/**
* Node toString
* @method toString
* @return {string} string representation of the node
*/
toString: function() {
return this._type + " (" + this.index + ")";
},
/**
* array of items that had the focus set on them
* so that they can be cleaned when focus is lost
* @property _focusHighlightedItems
* @type Array of DOM elements
* @private
*/
_focusHighlightedItems: [],
/**
* DOM element that actually got the browser focus
* @property _focusedItem
* @type DOM element
* @private
*/
_focusedItem: null,
/**
* Returns true if there are any elements in the node that can
* accept the real actual browser focus
* @method _canHaveFocus
* @return {boolean} success
* @private
*/
_canHaveFocus: function() {
return this.getEl().getElementsByTagName('a').length > 0;
},
/**
* Removes the focus of previously selected Node
* @method _removeFocus
* @private
*/
_removeFocus:function () {
if (this._focusedItem) {
Event.removeListener(this._focusedItem,'blur');
this._focusedItem = null;
}
var el;
while ((el = this._focusHighlightedItems.shift())) { // yes, it is meant as an assignment, really
Dom.removeClass(el,YAHOO.widget.TreeView.FOCUS_CLASS_NAME );
}
},
/**
* Sets the focus on the node element.
* It will only be able to set the focus on nodes that have anchor elements in it.
* Toggle or branch icons have anchors and can be focused on.
* If will fail in nodes that have no anchor
* @method focus
* @return {boolean} success
*/
focus: function () {
var focused = false, self = this;
if (this.tree.currentFocus) {
this.tree.currentFocus._removeFocus();
}
var expandParent = function (node) {
if (node.parent) {
expandParent(node.parent);
node.parent.expand();
}
};
expandParent(this);
Dom.getElementsBy (
function (el) {
return /ygtv(([tl][pmn]h?)|(content))/.test(el.className);
} ,
'td' ,
self.getEl().firstChild ,
function (el) {
Dom.addClass(el, YAHOO.widget.TreeView.FOCUS_CLASS_NAME );
if (!focused) {
var aEl = el.getElementsByTagName('a');
if (aEl.length) {
aEl = aEl[0];
aEl.focus();
self._focusedItem = aEl;
Event.on(aEl,'blur',function () {
//console.log('f1');
self.tree.fireEvent('focusChanged',{oldNode:self.tree.currentFocus,newNode:null});
self.tree.currentFocus = null;
self._removeFocus();
});
focused = true;
}
}
self._focusHighlightedItems.push(el);
}
);
if (focused) {
//console.log('f2');
this.tree.fireEvent('focusChanged',{oldNode:this.tree.currentFocus,newNode:this});
this.tree.currentFocus = this;
} else {
//console.log('f3');
this.tree.fireEvent('focusChanged',{oldNode:self.tree.currentFocus,newNode:null});
this.tree.currentFocus = null;
this._removeFocus();
}
return focused;
},
/**
* Count of nodes in a branch
* @method getNodeCount
* @return {int} number of nodes in the branch
*/
getNodeCount: function() {
for (var i = 0, count = 0;i< this.children.length;i++) {
count += this.children[i].getNodeCount();
}
return count + 1;
},
/**
* Returns an object which could be used to build a tree out of this node and its children.
* It can be passed to the tree constructor to reproduce this node as a tree.
* It will return false if the node or any children loads dynamically, regardless of whether it is loaded or not.
* @method getNodeDefinition
* @return {Object | false} definition of the tree or false if the node or any children is defined as dynamic
*/
getNodeDefinition: function() {
if (this.isDynamic()) { return false; }
var def, defs = Lang.merge(this.data), children = [];
if (this.expanded) {defs.expanded = this.expanded; }
if (!this.multiExpand) { defs.multiExpand = this.multiExpand; }
if (!this.renderHidden) { defs.renderHidden = this.renderHidden; }
if (!this.hasIcon) { defs.hasIcon = this.hasIcon; }
if (this.nowrap) { defs.nowrap = this.nowrap; }
if (this.className) { defs.className = this.className; }
if (this.editable) { defs.editable = this.editable; }
if (this.enableHighlight) { defs.enableHighlight = this.enableHighlight; }
if (this.highlightState) { defs.highlightState = this.highlightState; }
if (this.propagateHighlightUp) { defs.propagateHighlightUp = this.propagateHighlightUp; }
if (this.propagateHighlightDown) { defs.propagateHighlightDown = this.propagateHighlightDown; }
defs.type = this._type;
for (var i = 0; i < this.children.length;i++) {
def = this.children[i].getNodeDefinition();
if (def === false) { return false;}
children.push(def);
}
if (children.length) { defs.children = children; }
return defs;
},
/**
* Generates the link that will invoke this node's toggle method
* @method getToggleLink
* @return {string} the javascript url for toggling this node
*/
getToggleLink: function() {
return 'return false;';
},
/**
* Sets the value of property for this node and all loaded descendants.
* Only public and defined properties can be set, not methods.
* Values for unknown properties will be assigned to the refNode.data object
* @method setNodesProperty
* @param name {string} Name of the property to be set
* @param value {any} value to be set
* @param refresh {boolean} if present and true, it does a refresh
*/
setNodesProperty: function(name, value, refresh) {
if (name.charAt(0) != '_' && !Lang.isUndefined(this[name]) && !Lang.isFunction(this[name]) ) {
this[name] = value;
} else {
this.data[name] = value;
}
for (var i = 0; i < this.children.length;i++) {
this.children[i].setNodesProperty(name,value);
}
if (refresh) {
this.refresh();
}
},
/**
* Toggles the highlighted state of a Node
* @method toggleHighlight
*/
toggleHighlight: function() {
if (this.enableHighlight) {
// unhighlights only if fully highligthed. For not or partially highlighted it will highlight
if (this.highlightState == 1) {
this.unhighlight();
} else {
this.highlight();
}
}
},
/**
* Turns highlighting on node.
* @method highlight
* @param _silent {boolean} optional, don't fire the highlightEvent
*/
highlight: function(_silent) {
if (this.enableHighlight) {
if (this.tree.singleNodeHighlight) {
if (this.tree._currentlyHighlighted) {
this.tree._currentlyHighlighted.unhighlight();
}
this.tree._currentlyHighlighted = this;
}
this.highlightState = 1;
this._setHighlightClassName();
if (this.propagateHighlightDown) {
for (var i = 0;i < this.children.length;i++) {
this.children[i].highlight(true);
}
}
if (this.propagateHighlightUp) {
if (this.parent) {
this.parent._childrenHighlighted();
}
}
if (!_silent) {
this.tree.fireEvent('highlightEvent',this);
}
}
},
/**
* Turns highlighting off a node.
* @method unhighlight
* @param _silent {boolean} optional, don't fire the highlightEvent
*/
unhighlight: function(_silent) {
if (this.enableHighlight) {
this.highlightState = 0;
this._setHighlightClassName();
if (this.propagateHighlightDown) {
for (var i = 0;i < this.children.length;i++) {
this.children[i].unhighlight(true);
}
}
if (this.propagateHighlightUp) {
if (this.parent) {
this.parent._childrenHighlighted();
}
}
if (!_silent) {
this.tree.fireEvent('highlightEvent',this);
}
}
},
/**
* Checks whether all or part of the children of a node are highlighted and
* sets the node highlight to full, none or partial highlight.
* If set to propagate it will further call the parent
* @method _childrenHighlighted
* @private
*/
_childrenHighlighted: function() {
var yes = false, no = false;
if (this.enableHighlight) {
for (var i = 0;i < this.children.length;i++) {
switch(this.children[i].highlightState) {
case 0:
no = true;
break;
case 1:
yes = true;
break;
case 2:
yes = no = true;
break;
}
}
if (yes && no) {
this.highlightState = 2;
} else if (yes) {
this.highlightState = 1;
} else {
this.highlightState = 0;
}
this._setHighlightClassName();
if (this.propagateHighlightUp) {
if (this.parent) {
this.parent._childrenHighlighted();
}
}
}
},
/**
* Changes the classNames on the toggle and content containers to reflect the current highlighting
* @method _setHighlightClassName
* @private
*/
_setHighlightClassName: function() {
var el = Dom.get('ygtvtableel' + this.index);
if (el) {
el.className = el.className.replace(/\bygtv-highlight\d\b/gi,'ygtv-highlight' + this.highlightState);
}
}
};
YAHOO.augment(YAHOO.widget.Node, YAHOO.util.EventProvider);
})();
Copyright © 2009 Yahoo! Inc. All rights reserved.
|
__label__pos
| 0.999053 |
Journal of Sports Medicine and Physical Fitness, دوره (62), شماره (9), سال (2022-8)
عنوان : ( Interactive effect of exercise training and growth hormone administration on histopathological and functional assessment of the liver in male Wistar rats )
نویسندگان: امیر رشیدلمیر , Roozbeh , Reza Bagheri , مهتاب معظمی , زهرا موسوی , علی جوادمنش , Julien S Baker , Alexei Wong ,
بر اساس تصمیم نویسنده مقاله دسترسی به متن کامل برای اعضای غیر دانشگاه ممکن نیست
استناددهی: BibTeX | EndNote
چکیده
BACKGROUND: Abuse of growth hormone (GH) is expanding in exercising populations due to its lipolytic and anabolic actions. The purpose of this study was to examine the interactive effect of exercise training and GH administration on histopathological and functional assessment in the liver of male Wistar rats. METHODS: Forty-eight male Wistar rats were randomly divided into six groups including control + saline group (CS), GH injection group (GI), resistance training + saline group (RS), aerobic training + saline group (AS), resistance training + GH injection group (RG), aerobic training + GH injection group (AG). All groups were injected with either saline or GH 1 h before each training session. RT and AT were performed five days/week for a total of 8-weeks. At the end of the study, blood samples and liver tissue samples were taken to evaluate circulating AST, ALT, and ALP enzymes, as well as albumin protein. Histopathology of liver tissue was performed via qualitative microscopic evaluation. RESULTS: Microscopic evaluation of liver tissue did not show any histopathologic changes. All the groups administered with GH showed a significant increase in ALT, ALP, and albumin protein (P<0.05). However, AST enzyme concentrations increased significantly only in the RG group (P=0.022). In addition, neither RS nor the AS groups showed significant AST, ALT, and ALP changes, but serum albumin concentration significantly increased in the AS group (P=0.033). CONCLUSIONS: The elevation of liver enzymes showed that GH administration with or without exercise training might cause severe liver damage.
کلمات کلیدی
Sports; Exercise; Liver function tests
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@article{paperid:1092244,
author = {رشیدلمیر, امیر and Roozbeh and Reza Bagheri and معظمی, مهتاب and موسوی, زهرا and جوادمنش, علی and Julien S Baker and Alexei Wong},
title = {Interactive effect of exercise training and growth hormone administration on histopathological and functional assessment of the liver in male Wistar rats},
journal = {Journal of Sports Medicine and Physical Fitness},
year = {2022},
volume = {62},
number = {9},
month = {August},
issn = {0022-4707},
keywords = {Sports; Exercise; Liver function tests},
}
[Download]
%0 Journal Article
%T Interactive effect of exercise training and growth hormone administration on histopathological and functional assessment of the liver in male Wistar rats
%A رشیدلمیر, امیر
%A Roozbeh
%A Reza Bagheri
%A معظمی, مهتاب
%A موسوی, زهرا
%A جوادمنش, علی
%A Julien S Baker
%A Alexei Wong
%J Journal of Sports Medicine and Physical Fitness
%@ 0022-4707
%D 2022
[Download]
|
__label__pos
| 0.584177 |
Main Content
Configure Standard Math Library for Target System
Specify standard library extensions that the code generator uses for math operations. When you generate code for a new model or with a new configuration set object, the code generator uses the ISO®/IEC 9899:1999 C (C99 (ISO)) library by default. For preexisting models and configuration set objects, the code generator uses the library specified by the Standard math library parameter.
If your compiler supports the ISO®/IEC 9899:1990 (C89/C90 (ANSI)), ISO/IEC 14882:2003(C++03 (ISO) or ISO/IEC 14882:2011(C++11 (ISO)) math library extensions, you can change the standard math library setting. The C++03 (ISO) or C++11 (ISO) library is an option when you select C++ for the programming language.
The C99 library leverages the performance that a compiler offers over standard ANSI C. When using the C99 library, the code generator produces calls to ISO C functions when possible. For example, the generated code calls the function sqrtf(), which operates on single-precision data, instead of sqrt().
To change the library setting, use the Configuration Parameters>Standard math library parameter. The command-line equivalent is TargetLangStandard.
Generate and Inspect ANSI C Code
1. Open the example model rtwdemo_clibsup.
2. Generate code.
### Starting build procedure for: rtwdemo_clibsup
### Successful completion of code generation for: rtwdemo_clibsup
Build Summary
Top model targets built:
Model Action Rebuild Reason
===================================================================================
rtwdemo_clibsup Code generated Code generation information file does not exist.
1 of 1 models built (0 models already up to date)
Build duration: 0h 0m 12.883s
3. Examine the code in the generated file rtwdemo_clibsup.c. Note that the code calls the sqrt function.
if (rtb_Abs2 < 0.0F) {
rtb_Abs2 = -(real32_T)sqrt((real32_T)fabs(rtb_Abs2));
} else {
rtb_Abs2 = (real32_T)sqrt(rtb_Abs2);
}
Generate and Inspect ISO C Code
1. Change the setting of Standard math library to C99 (ISO). Alternatively, at the command line, set TargetLangStandard to C99 (ISO).
2. Regenerate the code.
### Starting build procedure for: rtwdemo_clibsup
### Successful completion of code generation for: rtwdemo_clibsup
Build Summary
Top model targets built:
Model Action Rebuild Reason
===================================================================================
rtwdemo_clibsup Code generated Code generation information file does not exist.
1 of 1 models built (0 models already up to date)
Build duration: 0h 0m 15.679s
3. Reexamine the code in the generated file rtwdemo_clibsup.c. Now the generated code calls the function sqrtf instead of sqrt.
if (rtb_Abs2 < 0.0F) {
rtb_Abs2 = -sqrtf(fabsf(rtb_Abs2));
} else {
rtb_Abs2 = sqrtf(rtb_Abs2);
}
Related Information
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__label__pos
| 0.981531 |
The Open Loop Power Control require in cdma due to following reason.
• Assumes Loss is Similar on Forward paths and Reverse Paths
• Receive Power + Transmit Power = -73
1. All Powers in dBm
• Example: For a Received Power of -85 dBm
1. Transmit Power = (-73) – (- 85)
2. Transmit Power = +12 dBm
• Provides an Estimate of Reverse TX Power for Given Propagation Conditions
Open loop power control is based on the similarity of the loss in the forward path to the loss in the reverse path (forward refers to the base-to-mobile link, while reverse refers to the mobile-to-base link).
Open loop control sets the sum of transmit power and receive power to a constant, nominally -73, if both reverse and forward powers are in dBm. A reduction in signal level at the receive antenna will result in an increase in signal power from the transmitter.
For example, assume the Forward received power from the base station is -85 dBm. This is the total energy received in the 1.23 MHz receiver bandwidth. It includes the composite signal from the serving base station as well as from other nearby base stations on the same frequency.
The open loop transmit power setting for a received power of -85 dBm would be +12 dBm. Thus open loop power control adjusts the transmit power of the phone to match the propagation conditions that the phone is experiencing at any given time.
By the TIA/EIA-98 standard specification, the open loop power control slew rate is limited to roughly match the slew rate of closed loop power control directed by the base station. This eliminates the possibility of open loop power control suddenly transmitting excessive power in response to a receiver signal level dropout.
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Open access
Electro-Surgery Practices and Complications in Laparoscopy
Written By
Ming-Ping Wu
Submitted: 08 November 2010 Published: 23 August 2011
DOI: 10.5772/20301
From the Edited Volume
Advanced Gynecologic Endoscopy
Edited by Atef Darwish
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1. Introduction
Operative laparoscopy is widely accepted as an efficacious technique in the treatment of gynecologic lesions. The patients, as well as the surgeons, may enthusiastically accept these new minimally invasive techniques in treating gynecologic as well as surgical diseases [1]. Since the introduction of the small medical video camera in the mid-1980s, the advent of laparoscopic surgery has brought a revolution in surgical techniques with shorter hospitalization and convalescence [2],[3]. However, surgeons who are well trained in open techniques do not automatically have that same status in laparoscopic cases. Therefore, surgeons who are skilled in open techniques may still require further training to become adapted with laparoscopic techniques. The required spatial orientation, hand-eye coordination and manipulative skills under laparoscopy are quite different [4]. All surgeons are aware of their own “learning curves”, during which time complication rates may be appreciable [4],[5]. Although the complication rate may decrease when more experience is gained with the laparoscopic procedure, the increasingly advanced and difficulty procedures performed by the gynecologists via laparoscopic further potentiates the higher risk of complications [6].
The rapidity of the uptake of these procedures into routine use and numerous adverse outcomes have raised justifiable concern [7],[8]. According to Magrina et al. review among 1,549,360 patients, the overall laparoscopic complication rate ranges 0.2-10.3% [6]. An early learning curve with limited cases may account for the high complication rate up to 10.3% (47 of 452 patients) [9, 10]. In a Finnish national-wide study [11], the major complication rate in overall gynecologic laparoscopies was 0.4% (130/ 32,205) among total procedures, and 1.26% (118/ 9,337) in operative laparoscopies. In an American Association Gynecologic Laparoscopy (AAGL) membership survey for laparoscopic-assisted vaginal hysterectomy (LAVH) was 6.59% (983/ 14,911) [12]. In Taiwan, Lee et al. reported the major complication rate 1.66% (12/ 722) in LAVHs group [13]; Wu et al. reported 1.59% (24/ 1,507) [14] and 0.72% (31/4307) in the follow-up study [15]. Since laparoscopic surgery is highly experience-dependent, follow-up studies in different study periods deserve continuous attentions.
Urinary bladder and bowel injuries comprise the main part of the complications. Bladder injuries are relatively common in the gynecologic field, especially in LAVHs. The complication rate was 2.4% (22/9,337) in Finnish study [11], and 1.08% (161/14,911) in AAGL study [12]. In Taiwan, Lee et al. reported 0.8% (6/722) [13]; it was 0.40% (6/1,507) [14] and 0.30% (13/ 4107) in Wu et al. follow-up study [15]. Bowel injuries, although not common, is one of the most serious complications when not detected and managed promptly. van der Voort et al. reported, based on 29 studies, the incidence of laparoscopy-induced gastrointestinal injury was 0.13 % (430/ 329,935) and of bowel perforation 0.22 % (66/ 29,532). The incidence may be under-reported due to retrospective and complication that occurred after leaving hospital being overlooked [16].The small intestine was most frequently injured 55.8 % (227/ 407), followed by the large intestine 38.6% (157/ 407), and the stomach 3.9 % (16/ 407) [17]. The reported bowel injury rates ranged from 0.16% (15/ 9,337) [11] to 0.62% (93/ 14,911);[12] 0.28% (2/ 722) in Lee et al. LAVHs stud;[13] 0.33% (5/ 1,507) in Wu et al. study.[14], and 0.16% (7/ 4,107) in the follow-up study [15]. Nevertheless, laparoscopy-induced bowel injury is associated with a high mortality rate of 3.6% [17].
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2. Electrosurgery use in laparoscopic surgery
The behavior of electricity in living tissue is generally governed by Ohm’s law:
Voltage (V)= current (I) x resistance (R)
Electrical current flows through a continuous circuit. Voltage is the necessary electromotive force that mediates or drives this electron movement through the circuit. Heat is produced when electrons encounter resistance [18]. The electricity has the following characteristics, which how it works and how it associates complications: i.e. (i) electricity takes the path of least resistance, (ii) seeks ground, and (iii) must have a complete circuit to do work [18].Understanding the electrosurgical principles is essential for using appropriate currents and techniques to achieve the desired tissue effect and to avoid complication [19].
Electrosurgical units (ESUs) are the most common piece of electrical equipment in the operating room. The constant presence of the ESU in the operating room assists surgeon to achieve desired tissue effect, but also increases the potential for electrosurgical injury [20]. With electrosurgery, we can achieve tissue effects such as cutting (also called vaporization), fulguration (also called superficial coagulation, or spray coagulation), and desiccation (also called deep coagulation) [20],[21],[22]. Primary factors that determine tissue effects of electrosurgery include energy modality (monopolar or bipolar), generator power output (watts), the alternating current waveform, the current density, and surgical techniques.
1. Energy modality, i.e., monopolar and biopolar. In monopolar electrosurgery, the current flows starts with the active electrode, through the patient and the return electrode for the completion of the circuit [21]. With monopolar current, the instrument tip is one pole, whereas the second pole is the grounding pad. In bipolar electrosurgery, both active and return electrodes are located at the surgical field, typically within the instrument tip [21]. The electrodes are only millimeters apart, therefore relatively low power of bipolar systems are needed to desiccate the tissue [23]. The power output of bipolar instruments is one-third to one-tenth that of monopolar systems.
2. Generator power output is most often indicated via a digital readout on the face of the generator. Others may have a logarithmic scale from 1 (lowest) to 10 (highest), making exact settings and adjustments more difficult [20],[18],[23]. Surgeons should understand what kind of generator they use and in what scale the power is presented.
3. Alternating current waveforms include cut waveform (continuous, non-modulated, undamped), blended waveform (different percentage duty cycle), and coagulation waveform (interrupted, modulated, damped), which are used for different surgical aims [20],[18],[23]. However, these labels are misleading because they do not necessarily produce the tissue effects that are associated with the terms “cut” and “coagulation” [23]. In fact, “cut” waveform can coagulate, and “coagulation” waveform can cut. Moreover, “cut” waveform is often the most appropriate current to use for tissue coagulation [23]. A cut waveform incorporates higher current but lower voltage than coagulation waveforms at the same power setting. As contrast, coagulation waveform has higher voltage and lower current than a cut waveform of the same power setting [18]. Therefore, with the same wattage, coagulation waveform has a much higher voltage than cut current. Higher voltages are more likely to produce unwanted effects and injuries than lower voltages. In more simple terms, for the same power levels, cut waveform produce less charring and tissue damage [23].
4. Current density depends on the area of surface contact, and the shape or size of the electrode [20],[18],[23]. Current density can affect the tissue effect as well as the heat production. The greater the current that passes through an area, the greater the effect will be on the tissue. Also, the greater the amount of heat that is produced by the current, the greater the thermal damage on tissue [18]. Heat generated at the tissue is inversely proportional to the surface area of the electrode. Smaller electrodes provide a higher current density and result in a concentrated heating effect at the site of tissue contact [18]. When the contact area is decreased by a factor of 10 (e.g. 2.5 cm2 to 0.25 cm2), the current density increases by a factor of 100 (e.g. 0.01 amp/cm2 to 1 amp/cm2), and the resulting final temperature increases from 37oC to 77oC. Thus, a small contact area produces high enough temperatures to cut [24],[22].
5. Surgical techniques include hand-eye coordination, speed of procedure, proximity between the electrode and the tissue, and dwell time [20],[18],[23]. During the learning curve, hand-eye coordination difficulties may be encountered involve working in a two-dimension environment with their hands generally disassociated from their eyes, esp. in radically new operative skills [25]. The speed of procedure will result in either less or more coagulation and thermal spread [18]. Proximity between the electrode and the tissue can determine contact (e.g. desiccation effect) or non-contact tissue effect, e.g. fulguration effect [23]. The dwell time determines the amount of tissue effect. Too long activation will produce wider and deeper tissue damage more than the anticipated desired tissue effect [18].
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3. Mechanisms of injury
The majority of laparoscopic complications happen subsequent to the followings: the entry to the peritoneal cavity, the delivery of energy to the surgical site (e.g. electrosurgery) and specific high-risk procedures [26]. A trocar or Veress needle caused the most bowel injuries 41.8% (114/ 273), followed by a coagulator or laser 25.6% (70/ 273). In 68.9 % of instances of bowel injury, adhesions or a previous laparotomy were noted [17]. Injuries during laparoscopic electrosurgical procedures can be attributed to misidentification of anatomic structures, mechanical trauma, and electro-thermal complications [12]. Misidentification and mechanical trauma can occur laparoscopically, just like that in laparotomy [27]. Moreover, surgical skills become more difficult when the surgeon’s spatial orientation and hand-eye coordination have not been well established.
Electro-thermal injury may result from the following situations: direct application, insulation failure, direct coupling, capacitive coupling, etc.
1. Direct application. Electrosurgical injury may happen via direct application similar to open laparotomy. It may be due to unintended activation of the electrosurgical probe, e.g. moving from the intended operating area to an iliac artery or vein on the pelvic sidewall, or operating on a moving ovarian cyst [28].
2. Insulation failure-induced stray current occurs when damage occurs to the covering of the active electrode, allowing the current to contact non-target tissue, which is often out of view of the surgical team members. Pre-operative careful inspection of the equipment before and after use is the best means of identifying defective insulation [20]. Two major causes of insulation failure include the use of high voltage currents and the frequent re-sterilization of instruments which can weaken and break the insulation [21]. Breaks in the insulation create alternate pathways for current to flow. With a high enough concentration of current, injury to adjacent organs is possible. This occurs primarily when a coagulation waveform is used due to its high voltage output [21]. A common equipment defect is a break in insulation. The risk of a break may be increased when using a 5-mm insulated instrument through a 10-mm sleeve, or by repeated use of disposable equipment [20]. Extensive burns and operating room fires can occur from these current leaks with temperatures measured to be as high as 700 °C [29].
3. Coupling. Direct coupling occurs when the electrosurgical unit is accidentally activated while the active electrode is in close proximity to another metal instrument e.g. laparoscope, metal grasper forceps, within the abdomen [21]. Current from the active electrode flows through the secondary instrument through the pathway of least resistance, and potentially damages adjacent structures or organs in direct contact with the secondary instrument. Direct coupling can be prevented with visualization of the electrode in contact with the target tissue and avoiding contact with any other conductive instruments prior to activating the electrode [20]. Ito et al. reported a small bowel perforation after a thermal burn caused by contact with the end of the laparoscope during gynecologic laparoscopy [30]. The preventive maneuver is to activate the electrode only when it is fully visible and in contact with the target tissue [30]. However, one must keep in mind that the depth of penetration of thermal energy goes beyond that seen by the naked eye; therefore, unrecognized injuries can present later after progression of the damaged tissue [20].
Capacitive coupling occurs when two conductive elements or instruments are separated by an insulator and form stored energy. An electrostatic field is created between the two conductors such that current through one conductor is transmitted to the second conductor once the net charge exceeds the insulator's capacity [21]. The electric current is transferred from one conductor (the active electrode), through intact insulation, into adjacent conductive materials (e.g. bowel, etc) without direct contact. For example, in a hybrid trocar sleeve, i.e. a nonconductive (plastic) locking anchor is placed over a conductive (metal) sleeve, the plastic anchor will stop the transmission into the abdominal wall over a large surface. This results in capacitive coupling. It happens to adjacent bowel, and results in bowel burns. Although the most common example of a capacitor being created is the placement of an active electrode, surrounded by its insulation, down a metal trocar, this can also occur with plastic trocars [27],[29]. Capacitor coupling may be minimized by activating the active electrode only when it is in contact with target tissues, limiting the amount of time that the coagulation setting (with its high-voltage peaks) is used, and by using metal cannulas that allow stray current to be dispersed through the patient’s abdominal wall, not internal tissues [18],[23].
1. Return electrode burns. The primary purpose of the grounding (dispersive) pad is to prove the path of least resistance from the patient back to the generator and to ensure an area of low current density [31],[32]. To complete current circuit, the return electrode must be of low resistance with a large enough surface area to disperse the electrical current without generating heat. If the patient's return electrode not completely in contact with the patient's skin, or is not able to disperse the current safely, then the current exiting the body can have a high enough density to produce an unintended burn [21]. The quality of contact between the return electrode and the patient's skin can be compromised by excessive hair, adipose, bony prominences, presence of fluid, or scar tissue. It is important to have good contact between the patient and a dispersive pad [20]. No other object, including hair, clothes, gauzes, and so on, should be between the patient and the grounding pad
2. Alternative site burn can happen if the dispersive (ground) pad is not well attached to the patient’s skin [20]. When the dispersive pad is compromised in the quantity or quality of the pad/patient interface, electrical circuit can be completed by some small grounded contact points, thus producing high current densities and causing a burn. Examples of such contact points include electrocardiogram (EKG) leads, towel clip, intravenous stand or stirrup, and neurosurgical head frames [31],[32]. The stray current could be intensified if the return electrode was distant from the operating site or if the grounded sites occurred in the path between the active and return electrode. In the case of ground-referenced electrosurgical units, even if the return electrode was disconnected, electrosurgery would continue with current finding alternative pathways to return to the ground. Electrocution of the patient under these circumstances was possible [21].
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4. Preventive and adjuvant protective maneuvers
4.1. Pre-operative phase
1. Knowledge of electrosurgical biophysics. A thorough understanding of the biophysical principles of radio-frequency electrical energy is of supreme importance [20],[18],[23]. For example, when the generator output cannot accomplish tissue effects as expected, it should be suspected first that there is a defect in the ground plate or its connection, or that an alternative pathway for the current has been instituted [32].
2. Bowel preparation is important if it is anticipated that the large bowel is at risk [28]. It facilitates operative maneuvers by increasing intra-peritoneal free space and reducing inadvertent bowel trauma [33]. Additionally, bowel preparation reduces the severity of complications which may occur after bowel perforation. Also, the use of naso-gastric tube is recommended, esp. after several trials of endotracheal intubation, to diminish the possibility of a trocar entry into the stomach [15].
3. To choose proper current waveform mode. In monopolar electrosurgery, both “cut” or “coagulation” waveform can be used for either cutting effect or fulguration effect. A cutting current power setting must be between 50 and 80W to be effective. Typically, the coagulation current is effective with the power setting in the range of 30–50W. Although it is possible to cut tissue using coagulation currents at high power, the end result is greater charring and tissue damage [18]. Use bipolar instruments whenever possible [33].
4. To improve dexterity and hand-eye coordination through sequential phases of training, i.e. didactic phase, laboratory experience, observation and/or assistance, and preceptorship [25]. The chances of direct trauma are greater during laparoscopic surgery because the surgeon is limited to visualize in only two-dimensions, with surgeon’s hands generally dissociated from their eyes, esp. when operating on mobile organs [28],[34].
5. Team resource management (TRM). It is important to organize a laparoscopic team, including biomedical engineer, perioperative nurses and other operation room personnel, and promote extended education activities and participation in medical conferences. When adapting the wisdom of crew resource management (CRM) from aviation to medicine, there still some challenges. Surgical team also needs to improve team communication and coordination [35].
4.2. Intra-operative phase
1. Safe pneumo-peritonization and entry. The site of primary entry is usually the umbilicus, but there is a high risk of subumbilical adhesions that may contain bowel in patients with a history of previous laparotomy [26]. There is therefore a risk of injury to the bowel regardless of the entry method, and in these cases, consideration should be given to the use of an alternative site such as left upper quadrant, i.e. Palmer’s point [36]. Te Palmer's entry is safe with a lower failure rate in the patients with risks of underlying adhesions and more appropriate in the presence of a large pelvic mass or a nearby hernia [36]. Contraindications to the use of this site, such as hypersplenism or a distended stomach, should be excluded before entry [26]. The blind insertion of a Veress needle or first trocar to create the pneumoperitoneum has been shown to cause vascular and visceral injuries. No single insertion technique is universally safe and divorced from complications in establishing pneumoperitoneum. The use of the open laparoscopy method introduced by Hasson may reduce the likelihood of bowel injury in patients who are likely to have anterior wall adhesions [37]. Other techniques include a well-executed open technique with employment of digital pressure to and local adhesiolysis [38], and/or adjuvant instruments, e.g. optic access trocar [39],[40] can be offered as suggestion for reducing injuries. In addition, the radially expandable sleeve with a tapered blunt dilator and cannula has been proposed to a potential safer laparoscopic trocar access [41]. The radially expanding access system (STEP) trocar entry had less trocar site bleeding when compared with standard trocar entry [42]. The trocar-cannula systems with safety apparatus do not necessarily guarantee the safety during entrance of the abdominal wall, because the relatively thick plastic shields need extra effort push the shield through the transveralis fascia and peritoneum [31],[43].
2. To identify individual anatomic variation. Left and right pelvic anatomic locations are not necessarily mirror images, laparoscopically. The course of the inferior epigastric vessels can be more difficult to identify in overweight patients. The proximity of the ureter to the uterosacral and infundibulopelvic ligaments reaffirms the need to identify them before dissection [44].
3. The adequate electrosurgical techniques, e.g. do not activate electrode in the air, converting to laparotomy when indicted. Activating the electrode in the air, when not in use, will create an ‘open circuit’, which can result in a capacitive current effect, too. Capacitive coupling is increased by open circuits, use of 5-mm cannulas (versus 10 mm), and higher generator voltages [45]. This situation can be avoided by using multiple, short activation time that allows normal tissue to remain cool [27]. Meanwhile, do not activate the instrument in close proximity or direct contact with another instrument [21]. Activate the electrode only when whole tissue is in the field of vision, to minimize the chances of direct trauma. After the use of electrosurgery, keep it in view until it has cooled or removed from the body [33]. Meanwhile, surgeons should learn to operate via traditional laparotomy before progressing to laparoscopy. In order to minimize complications, trainees need to become proficient at converting to laparotomy when the procedure cannot be completed laparoscopically [25],[28].
4. The adequate use of current waveform and advanced biopolar facility. By lowering the concentration of the current used, coagulating with a cutting current, and using an active electrode monitoring system, the risk of accidental burns caused by insulation failure can be reduced [21]. Advanced bipolar facility include: Ligasure (Valley Lab Covidien, Boulder, CO, U.S.A), Gyrusw Olympus Gyrus ACMI (Maple Grove, MN, U.S.A), EnSeal (Ethicon Endo-Surgery, Cincinnati, OH, U.S.A). Ligasure combined the technology of pressure and bipolar energy; Gyrus used pulsed bipolar energy; EnSeal combined high levels of pressure and temperature sensitive electrodes [46].
5. To use electrosurgical accessory safety equipment when possible. A return electrode monitoring system (REM) is a dual-padded patient return electrode system designed to monitor irregular separation of the ground pad. It can actively monitor tissue impedance (resistance) at the contact between the patient’s body and the patient return electrode, and interrupts the power if the quality and/or quantity are compromised. REM can monitor and assist to avoid return electrode burn. This system inactivates the generator if a condition develops at the patient return electrode site that could result in a burn [20]. Active electrode monitoring (AEM) e.g. Encision, Inc, (Boulder, CO, U.S.A), was developed to minimize the risks of insulation failure and capacitive coupling, active electrode monitoring systems now exist [21]. When interfaced with electrosurgical units, these systems continuously monitor and shield against the occurrence of stray electrosurgical currents. Critical to the success of these systems are the integrated laparoscopic instruments which have a secondary conductor within the shaft that provides coaxial shielding [21]. If any stray energy is sensed, the radiofrequency generator shuts down before a burn can occur [46]. The use of an active electrode monitoring system and limiting the amount of time that a high voltage setting is used can also eliminate concerns about capacitive coupling [20].
Tissue response technology (TRT) uses a computer-controlled tissue feedback system that automatically senses resistance of the tissue and adjusts the output voltage to maintain a consistent effect across different tissue density, to achieve a consistent tissue effect. Newer generator constantly monitor impedance to maintain the preset wattage over a broad range of impedance, avoiding unnecessary higher wattage with potential hazards [28]. Improved performance can now be achieved at lower electrosurgical settings [47]. Vessel sealing technology, which combines with bipolar electrosurgery with tissue response generators and optimal mechanical pressure, can seal and fuse vessel walls up to 7 mm in diameter [21]. This technology delivers high current and low voltage to the targeted tissue and denatures the vessel wall protein; the mechanical pressure allows the denatured protein to form a coagulum [48]. Thermal spread appears to be reduced when compared to traditional bipolar electrosurgical systems. Valleylab, Gyrus ACMI, and SurgRx, Inc. are three companies which have developed devices for both open and laparoscopic applications [48],[49],[50]. Smoke evacuation scavenger system can improve the operation field from smoggy atmosphere. It also protects patients, as well as surgical staffs, from the exposure of smoke and the byproducts during laparoscopic procedures [51].
To use adjuvant protective procedure. Some adjuvant protective procedures were suggested during laparoscopic surgeries. In addition to these preventive maneuvers, Wu et al. inserted a bladder retractor via urethral meatus into the bladder cavity to identify the utero-vesical space, especially in cases with dense fibrotic adhesion (Fig. 1). The bladder retractor with oval-shaped tip can mobilize the bladder and counter-act with the uterine mobilizer to expose vesico-uterine space at an adequate distance, which was not achieved easily with standard laparoscopic techniques [52]. Lin and Chou conducted a modified procedure of Laparoscopic assisted vaginal hysterectomy (LAVH) by preligating the uterine arteries, in which a pair of polydioxanone (PDS) clips were placed at the uterine artery located between the ureter and the bifurcation of the hypogastric artery before the uterine vessels were desiccated [53]. Chang et al. use the retrograde umbilical ligament tracking method for uterine artery ligation to prevent excessive bleeding from uterine vessels and ureterhal thermal injury, especially in huge uterine size [54]. The adjuvant protective procedures may account, at least in part, for the lower ureteral injury rate [15]. A high index of suspicion and prior visualization and/or retroperitoneal dissection of the ureter, will be helpful in decreasing ureteral injury [55].
Figure 1.
A bladder retractor via urethral meatus into the bladder cavity to identify the utero-vesical space in cases with dense fibrotic adhesion.
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5. Recognition of complication and salvage procedures
5.1. Intra-operative phase
1. Entry (Veress- or trocar-) related. The treatment of bowel injuries depends upon the extent of damage. If the Veress needle has been inserted into a hollow viscus without tearing, no further therapy is indicated, since its small diameter leaves no defect; and the muscular wall will close over this puncture spontaneously [33]. However, when the insertion of the trocar into a small intestine, leaves a large defect, e.g. one-half the diameter of the lumen, a segment resection and anastomosis should be performed through laparotomy. If the perforation has occurred, it may be beneficial to leave the trocar in situ to serve to identify the site of laceration [56].
2. Urinary tract injury. Bladder injury can be detected by direct visualization of either bladder mucosa or Foley balloon (Fig. 2). If a bladder injury at laparoscopy is suspected but not immediately identified, diluted methylene blue should be instilled into the bladder via a Foley catheter. The bladder will be seen to fill and the dye will leak out through any lacerations [26]. To observe the gas leakage into the urine bag intra-operatively is another detection methods [15]. When bladder injury was recognized intra-operatively, it can be repaired vaginally, laparoscopically or by laparotomy without incident (Fig. 3). Early recognition with immediate salvage procedure could overcome further sequelae [57]. The extended use of an indwelling catheter should be considered.
Figure 2.
Bladder injury detected by direct visualization of bladder mucosa and Foley balloon.
Ureteral injuries in gynecologic laparoscopy usually are not recognized intraoperatively, only those patients with persistent abdominal and/or flank pain, abdominal distention, and fever may raise the cautions during post-operative phase [55]. Those intra-operative recognized ureteral injuries can be solved by direct laparoscopic end-to-end reanastomosis (Fig. 4). It can be also resolved by double-J ureteral stent with or without the assistance of ureteroscopy (Fig. 5). If the initial salvage procedure fails, percutaneous nephrostomy and antegrade ureteral double-J stent is a backup procedure to avoid the subsequent ureteral fistula.
Figure 3.
Bladder injury was recognized intra-operatively, and was repaired vaginally.
Figure 4.
Ureteral injuries recognized intraoperatively and was repaired by laparoscopic end-to-end reanastomosis.
Figure 5.
Ureteral injuries recognized intraoperatively with the assistance of ureteroscopy.
Bowel injury. The time of diagnosis was reported 61.6% (154/ 250) recognized during surgery; 5.2% (13/ 250) recognized early post-operative phase within the next 48 hours; 10.4% (26/ 250) bowel injuries diagnosed late, at least on the third postoperative day or later. Another 22.8% (57/250) diagnosed after the conclusion of surgery, the number of hours elapsed was not reported [17]. A laparotomy was most frequently performed to manage the laparoscopy-induced bowel injury (78.6%). Conservative (7.0%) and laparoscopic (7.5%) treatment were used considerably less often [58],[17].
Stomach injury is a rare complication, it may be encountered after several trials of endotracheal intubations (Fig. 6). The inadvertent endotracheal intubation can cause excess gas inflated into the stomach and displaced the hyperinflated stomach as low as the periumbilical area [15]. Naso-gastric intubation for decompression is helpful to prevent gastric injury for those cases with distended stomach. Injury to small bowel or prepped colon, primary closure in two layers under laparoscopic guidance is recommended [33]. In selected cases with trocar-induced penetrating injuries of the bowel, institution of drainage and antibiotics can allow possible medical management of the problem, and thereby preclude conversion to laparotomy [59]. Conservative management comprised percutaneous drainage of abscesses, antibiotics or expectant treatment [17].
Figure 6.
Stomach injury by the introduction of primary trocar after several trials of endotracheal intubations.
When a large bowel injury is identified at the time of surgery, it is appropriate to repair this immediately, usually with the direct involvement of colorectal surgical colleagues [26]. The exact technique of repair will depend on the size of the injury, the exact site, and whether bowel preparation has been performed before surgery. As for colon injury, the transverse colon and sigmoid colon are most commonly traumatized by the trocar insertion. The spillage of foul-smelling gas through the insufflation needle is a helpful diagnostic sign [56]. The treatment options include primary repair, colostomy or segmental resection [33]. Superficial lesions can be treated with a laparoscopic purse-string suture placed beyond the margins of the thermally affected tissue or by postoperative observation alone [28]. Defects involving the full thickness of the bowel wall require direct surgical repair via laparoscopy or open lapaarotomy [56]. A suture to oversaw a lesion was performed mainly for serosal damage or burn sites, and for perforations that were discovered immediately [17]. Primary closure of the perforation trauma was reported to be a safe method, with a failure rate varying from 1.2% to 2.4 %, as an alternative to traditional colostomy if the absence of contraindication. The contraindication included more than two associated injuries, the need for blood transfusion over 4 units, significant contamination, increasing colon injury severity scores [60]. A laparoscopic suture closure followed by copious irrigation until the effluent becomes clear might be also satisfactory [61]. Suturing was the procedure most often performed at laparotomy, 63% times (61/ 97), followed by bowel resection with reanastomoses 26% (25/ 97). A diverting stoma was required 11 % (11/ 97) [17]. Full-thickness penetration of the rectum can occur during the excision of rectal endometriosis. After excision of the nodule of the recto-sigmoid colon, a single-or double-layered repaired can be done by laparoscopic assisted transvaginal approach or total laparoscopic intracorporeal technique [62]. Concerning the unprepared bowel with a large amount of fecal contamination, laparotomy followed by repair and colostomy should be considered [33].
Electro-thermal effect. The sigmoid colon is especially vulnerable because of its close proximity to the uterus and ovaries. Colon injury caused by bipolar electrosurgery can be readily identified by viewing the area of blanch on the surface of the colon, as compared with monopolar electrosurgery which is more difficult to detect and evaluate [28]. Superficial thermal injuries to the bowel may be treated prophylactically with a laparoscopic-guided pursestring suture placed beyond the thermally affected tissue [56]. The spread of electro-thermal injuries is greater than the initial area of branching and can create a large area of necrosis; thus the depth of injury is difficult to assess even if they are noticed intraoperatively. The injury of a viscus or bile duct typical occurs only after several days have elapsed [31]. Thermal injury of the bowel necessitates segmental resection with a wide margin around the site of injury because thermal damage may extend for a considerable distance from the site of thermal contact (several centimetres) [33]. Excision of a generous segment up to 5 cm on each side of the margin of the injury site, to include this area of coagulation necrosis, is required to prevent subsequent reperforation. Currently, the best way to treat bowel injury during laparoscopic surgery is by traditional laparotomy. However, as laparoscopists become more experienced in laparoscopic surgery, laparoscopic suture repair will become another choice in the management [13]. The efficiency and accuracy of laparoscopic bowel suturing techniques have been proposed. In Reich’s series, there are few indications for colostomy during the repair of bowel injuries noted during the course of a laparoscopic procedure [56].
5.2. Post-operative phase
Being highly alert to postoperative warning signs. During postoperative observation period, which may last 3 to 5 days, the surgical team should be highly alert to the early manifestations of peritonitis, especially for physicians who are on duty for coverage. Isolated small intestine injuries may not cause clear or rapid symptoms and abnormal laboratory values, while colon injury with or without combined ileal injuries, has grave outcomes. The degree of peritonitis depends on the amount of spillage and length of time between perforation and exploration. However, these warning signs may be insidious, and imply the importance of possible early intervention. For example, persistent excessive external fluid leak from the periumbilical area after laparoscopic surgery with no drainage from other incisional sides may suggest small-bowel injury. latrogenic, internal-external canalization between the small intestine and the skin masked clinical symptoms and signs of small-intestinal injury [63].
Abnormal laboratory and imaging tests are helpful in confirming the diagnosis, however, normal test result is not reassuring. Patients who do not void may have early manifestation of bowel injury. Lack of classic symptoms, signs, or changes in pertinent laboratory data did not rule out small-bowel perforation [63].
Figure 7.
Vesico-vaginal fistula happened with the delayed deterection of bladder injury.
Patient education before discharge. Bowel injury that is unrecognized at the time of surgery is one of the most dangerous complications of laparoscopic surgery. All patients undergoing laparoscopy must be advised before discharge that they should feel progressively better, and that any worsening in their condition should prompt them to seek advice [26]. They may well make a reasonable initial recovery and be discharged home. Once at home, they may become unwell, develop pain and fever and start vomiting. On seeking medical help, it is essential that the attending staff have a very high degree of suspicion of bowel injury. In the case of postoperative peritonism or peritonitis, the early use of computed tomography scanning can be very useful in the diagnosis of bowel obstruction secondary to a port site hernia. Increasing abdominal pain after laparoscopic surgery demands an expedient evaluation, even if it requires a repeated laparoscopy with a negative finding [34]. The involvement of general surgeons and early recourse to exploratory surgery is essential to prevent a poor outcome [26].
Delay detection of bladder injury may result in vesico-vaginal fistula which demand repetitive repair if the first salvage procedure failed (Fig. 7) [15]. If a ureteric injury is suspected but not confirmed at the time of initial surgery, an intravenous pyelogram should be performed. Urological colleagues should be involved in the management of these complication [26]. Once ureteral injury was detected in a late post-operative period after the formation of ureteral fistula, ascites with urine content (urinoma) might complicate the situation. Laparotomy for end-to-end anastomosis is usually necessary in the cases with complete transection, ligation or electro-thermal injury-induced ischemic necrosis [15].
Figure 8.
Tubo-ovarian abscess is a risk factor associated with bowel injuries.
Delay detection of bowel injury may cause high morbidity and mortality. van der Voort et al. reported overall mortality rate associated with bowel injury complication 3 6% (16/ 450) The [17]. The clinical picture may be varied. The early manifestation may be non-specific, e.g. vomiting, abdominal pain, distension and malaise; which is followed by additional features, e.g. a localized peritoneal abscess or generalized peritonitis [33]. In this stage, fever, leukocytosis and even septic shock can occur. Bowel injury caused by direct trauma or electrothermal injury has different clinical courses and histo-pathologic findings [64]. Symptoms of bowel perforation after electrical injury usually arise 4 to 10 days after the procedures, whereas symptoms of traumatic perforation usually occur within 12 to 36 hours [56],[65],[34]. Most electro-thermal injuries, more common in large bowel, are unrecognized intraoperatively and lead to long-term sequelae. It may occur insidiously due to stray current, insulation failure or capacitive coupling, in addition to direct, active electrode injury [65]. As for the timing of detection, van der Voort et al. reported more than 10% unrecognized until the third post-operative day or later [17]. In Wu et al. series, some identifiable risk factors associated with bowel injuries were emergent, non-scheduled surgeries, tubo-ovarian abscess or uncertain preoperative diagnosis (Fig. 8) [15]. The original injury severity, e.g. multiple injuries, happened more commonly in managing tubo-ovarian abscess, especially combined with appendicitis. They had grave outcomes with prolonged hospitalizations and demanded multiple salvage procedures.
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6. Conclusions
As complications are an inevitable reality of surgery, we need to be aware of the types of complications in a systematic way, train to respond in an appropriate way, and learn to communicate and deal with complications in laparoscopic surgery [8]. To achieve electrosurgical safety and to prevent potential electrosurgical injury, understanding the biophysics of electrosurgery, characteristics of their own equipment, desired tissue effects, types of injury, and the possible clinical manifestations are very important, as well as the mastering of laparoscopic surgical dexterity. Organizing a team-work including surgeons, perioperative nurses, biomedical engineers, and operation room personnel through team resource management. Intraoperative adjuvant protective maneuvers, early recognition and immediate implementation of salvage procedures will minimize the complications. Risk-aversive behaviors include paying particular attentions to placement of the first port, more liberal use of open laparoscopy or other adjuvant instrument, placement of all other ports under direct vision, elimination of intra-operative anatomy uncertainty, programmed inspection of the abdomen before withdrawing the laparoscope [31]. The dexterity improvement with hand-eye coordination and the knowledge of the mechanism of electrosurgical injury is important in recognizing and reducing potential electrosurgical complications [65]. Be highly alertness to postoperative warning signs including obvious signs of peritonitis or abdominal pain, and insidious ones. Patient education before discharge and detection of delay manifestation with salvage maneuver may minimize catastrophic disaster.
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Written By
Ming-Ping Wu
Submitted: 08 November 2010 Published: 23 August 2011
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What is REM Sleep? Boost Your REM Sleep for a Better Night
What is REM Sleep? Boost Your REM Sleep for a Better Night
Sleep is crucial to a healthy and happy life. However, not all sleep is equal. If you’re in the 70% of sleep-deprived adults, then getting more sleep overall will likely be beneficial. However, what you really need to aim for is more rapid eye movement (REM) sleep. This is a somewhat unique stage of sleep that many other animals never achieve. For human wellness, though, it’s essential. What is REM sleep, why is it important, and how can you boost yours?
The Rapid Eye Movement of Mammals
Rapid eye movement (REM) isn’t a trait all animals share. It’s mostly reserved for those species who need a deeper level of sleep, which, for the most part, means mammals. Some birds and reptiles also achieve this deep state of sleep, but it's more commonly seen among our mammalian cousins. Even elephants, those majestic and complex creatures, don’t achieve REM sleep daily. That’s because they only need two hours of sleep a night to function.
In general, the longer an animal sleeps, the more likely they are to enter REM sleep. Lions sleep an enviable 16 hours per day, while even our canine friends need up to 14. Primates are similar to humans in their sleep habits, with chimpanzees opting for an average of 9.7 hours a day. Gorillas need 12. These lengthy sleep periods leave plenty of time for mammals to enter their much-needed REM stage of sleep.
But what is REM sleep? Well, as the name implies, it’s a period of sleep where the eyes are rapidly darting in different directions under closed eyelids. You’ve probably seen your pet dog’s eyes doing this when they’re all curled up on the sofa and fast asleep. During the night, your body cycles between REM and non-REM sleep. For the first 30 minutes or so after dropping off, you’re in light sleep in which your heart rate begins to slow, and your body temperature drops. During this time, you can be easily awoken.
When Does REM Sleep Occur?
Around 90 minutes after you first dozed off, your body will enter REM. This first period of REM sleep lasts approximately 10 minutes; then, each subsequent period becomes longer. Your final REM sleep period could last up to an hour. In general, you’ll have between three and five REM cycles each night. For adults, this equates to around 25% of your total sleep time. Babies, meanwhile, can spend 50% of the night in REM.
Despite being in a deep sleep, your brain is actually at its most active during this time. Plenty is happening during REM sleep, and you’re at the point where your most vivid dreams will occur. It can be hard to wake up during this phase, but if you do, you’ll likely be confused for a few moments. You’ll have been so immersed in your dream world that suddenly transporting back to reality can be disorientating.
During this time, your heart rate goes up, and your internal body may appear very active. Fortunately, your legs will be temporarily paralysed to ensure you don’t start acting out your dreams. Towards the end of a healthy sleep cycle, you’ll begin to gently come out of REM and back into a light sleep before waking up.
Why is REM Sleep Important?
Sleep is an extraordinary and essential part of the day. There are three main reasons that scientists believe we need sleep. First, it’s a time when we consolidate information and strengthen memories. Second, it’s when the body repairs itself, which is why deep sleep is often prioritised after a period of sleep deprivation. Finally, it helps to conserve energy so that you have the boost you need to succeed during the day.
It seems that most of these benefits are derived during the REM stages of sleep. The more deeply you’re able to sleep during the night, the more you’ll receive the core benefits of sleep. It particularly seems to be the period when memories are sorted, helping your brain retain the information you learned during the day. That’s how REM sleep can make you smarter.
REM is also the period when dreams happen. The function of dreaming isn’t clear, but most agree that this mysterious quirk of being human is important for living a meaningful life. It seems that dreams help us process painful emotions and may play a role in creativity and problem-solving. The less you allow yourself to achieve REM sleep, the harder it will be to accrue these benefits.
How to Achieve Better REM Sleep
Now that you know what REM sleep is and why it’s so important, you’re probably wondering how to get more of it. This might seem difficult since you have no control over what’s happening when you’re asleep. However, there are plenty of habits you can form during the day which impacts the duration and quality of your REM sleep cycle.
One of the most significant factors is caffeine. We all know that drinking coffee and energy drinks before bedtime is a bad idea. It makes it harder to fall asleep, cutting down the number of hours you’re able to achieve. However, did you know that it doesn’t affect all sleep stages equally? No, it tends to cut into your REM sleep more than any other, leaving you with more hours of light sleep. Alcohol has the same effect.
Conversely, a hard workout seems to increase the amount of REM sleep you can achieve each night. Exercising before bed helps your body prioritise the deeper stages of sleep. However, remember to avoid rigorous exercise within the hour before bed since this can raise your energy levels and make it difficult to sleep.
When you don’t have time to hit the gym, you can consider using natural sleep aids like Neubria Drift. These induce a state of calm, helping you sleep more quickly, so you have ample time to go through all the necessary cycles of REM sleep.
So, what is REM sleep? It’s an incredible privilege that human beings are lucky to have access to. Of all the benefits we receive from sleeping, much occurs during the REM sleep stage. Therefore, it’s a good idea to try and spend more of your sleeping life in REM. To do this, consider cutting out caffeine and alcohol close to bedtime, working out more often, and taking natural supplements to increase the quantity and quality of your sleep.
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Documentation for /proc/sys/vm/* kernel version 2.2.10 (c) 1998, 1999, Rik van Riel For general info and legal blurb, please look in README. ============================================================== This file contains the documentation for the sysctl files in /proc/sys/vm and is valid for Linux kernel version 2.2. The files in this directory can be used to tune the operation of the virtual memory (VM) subsystem of the Linux kernel and the writeout of dirty data to disk. Default values and initialization routines for most of these files can be found in mm/swap.c. Currently, these files are in /proc/sys/vm: - overcommit_memory - page-cluster - dirty_ratio - dirty_background_ratio - dirty_expire_centisecs - dirty_writeback_centisecs - max_map_count - min_free_kbytes - laptop_mode - block_dump - drop-caches - zone_reclaim_mode - min_unmapped_ratio - min_slab_ratio - panic_on_oom ============================================================== dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, block_dump, swap_token_timeout, drop-caches: See Documentation/filesystems/proc.txt ============================================================== overcommit_memory: This value contains a flag that enables memory overcommitment. When this flag is 0, the kernel attempts to estimate the amount of free memory left when userspace requests more memory. When this flag is 1, the kernel pretends there is always enough memory until it actually runs out. When this flag is 2, the kernel uses a "never overcommit" policy that attempts to prevent any overcommit of memory. This feature can be very useful because there are a lot of programs that malloc() huge amounts of memory "just-in-case" and don't use much of it. The default value is 0. See Documentation/vm/overcommit-accounting and security/commoncap.c::cap_vm_enough_memory() for more information. ============================================================== overcommit_ratio: When overcommit_memory is set to 2, the committed address space is not permitted to exceed swap plus this percentage of physical RAM. See above. ============================================================== page-cluster: The Linux VM subsystem avoids excessive disk seeks by reading multiple pages on a page fault. The number of pages it reads is dependent on the amount of memory in your machine. The number of pages the kernel reads in at once is equal to 2 ^ page-cluster. Values above 2 ^ 5 don't make much sense for swap because we only cluster swap data in 32-page groups. ============================================================== max_map_count: This file contains the maximum number of memory map areas a process may have. Memory map areas are used as a side-effect of calling malloc, directly by mmap and mprotect, and also when loading shared libraries. While most applications need less than a thousand maps, certain programs, particularly malloc debuggers, may consume lots of them, e.g., up to one or two maps per allocation. The default value is 65536. ============================================================== min_free_kbytes: This is used to force the Linux VM to keep a minimum number of kilobytes free. The VM uses this number to compute a pages_min value for each lowmem zone in the system. Each lowmem zone gets a number of reserved free pages based proportionally on its size. ============================================================== percpu_pagelist_fraction This is the fraction of pages at most (high mark pcp->high) in each zone that are allocated for each per cpu page list. The min value for this is 8. It means that we don't allow more than 1/8th of pages in each zone to be allocated in any single per_cpu_pagelist. This entry only changes the value of hot per cpu pagelists. User can specify a number like 100 to allocate 1/100th of each zone to each per cpu page list. The batch value of each per cpu pagelist is also updated as a result. It is set to pcp->high/4. The upper limit of batch is (PAGE_SHIFT * 8) The initial value is zero. Kernel does not use this value at boot time to set the high water marks for each per cpu page list. =============================================================== zone_reclaim_mode: Zone_reclaim_mode allows to set more or less agressive approaches to reclaim memory when a zone runs out of memory. If it is set to zero then no zone reclaim occurs. Allocations will be satisfied from other zones / nodes in the system. This is value ORed together of 1 = Zone reclaim on 2 = Zone reclaim writes dirty pages out 4 = Zone reclaim swaps pages zone_reclaim_mode is set during bootup to 1 if it is determined that pages from remote zones will cause a measurable performance reduction. The page allocator will then reclaim easily reusable pages (those page cache pages that are currently not used) before allocating off node pages. It may be beneficial to switch off zone reclaim if the system is used for a file server and all of memory should be used for caching files from disk. In that case the caching effect is more important than data locality. Allowing zone reclaim to write out pages stops processes that are writing large amounts of data from dirtying pages on other nodes. Zone reclaim will write out dirty pages if a zone fills up and so effectively throttle the process. This may decrease the performance of a single process since it cannot use all of system memory to buffer the outgoing writes anymore but it preserve the memory on other nodes so that the performance of other processes running on other nodes will not be affected. Allowing regular swap effectively restricts allocations to the local node unless explicitly overridden by memory policies or cpuset configurations. ============================================================= min_unmapped_ratio: This is available only on NUMA kernels. A percentage of the total pages in each zone. Zone reclaim will only occur if more than this percentage of pages are file backed and unmapped. This is to insure that a minimal amount of local pages is still available for file I/O even if the node is overallocated. The default is 1 percent. ============================================================= min_slab_ratio: This is available only on NUMA kernels. A percentage of the total pages in each zone. On Zone reclaim (fallback from the local zone occurs) slabs will be reclaimed if more than this percentage of pages in a zone are reclaimable slab pages. This insures that the slab growth stays under control even in NUMA systems that rarely perform global reclaim. The default is 5 percent. Note that slab reclaim is triggered in a per zone / node fashion. The process of reclaiming slab memory is currently not node specific and may not be fast. ============================================================= panic_on_oom This enables or disables panic on out-of-memory feature. If this is set to 1, the kernel panics when out-of-memory happens. If this is set to 0, the kernel will kill some rogue process, called oom_killer. Usually, oom_killer can kill rogue processes and system will survive. If you want to panic the system rather than killing rogue processes, set this to 1. The default value is 0.
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Infinite sets of points in the Euclidean plane, even discrete sets, do not always have Euclidean minimum spanning trees. For instance, consider the points with coordinates
\[\left(i, \pm\left(1+\frac1i\right)\right),\]
for positive integers \(i\). You can connect the positive-\(y\) points and the negative-\(y\) points into two chains with edges of length less than two, but then you have to pick one edge of length greater than two to span from one chain to the other. Whichever edge you choose, the next edge along would always be a better choice. So a tree that minimizes the multiset of its edge weights (as finite minimum spanning trees do) does not exist for this example. And as the same example shows, the sum of edge weights may be infinite, so how can we use minimization of this sum to define a tree?
Discrete infinite set of points with no Euclidean minimum spanning tree
Despite that, here’s a construction that works for any compact set, even one with infinitely many components, and that generalizes easily to higher-dimensional Euclidean spaces. I think it deserves to be called the Euclidean minimum spanning tree. Given a compact set \(C\), consider every partition \(C=A\cup (C\setminus A)\) of \(C\) into two disjoint nonempty compact subsets. For each such partition, find a line segment \(s_A\) of minimum length with endpoints in \(A\) and \(C\setminus A\), breaking ties lexicographically by coordinates. By the assumed compactness of \(A\) and \(C\setminus A\), such a line segment exists. Let \(T_C\) be the union of \(C\) itself and of all line segments obtained in this way. For example, the union of a triangle, square, and circle shown below has three partitions into two nonempty compact subsets, separating one of these three shapes from the other two. Two of these partitions choose the diagonal pink segment as their shortest connection, and the third partition chooses the horizontal pink segment. So in this case, \(T_C\) consists of the three blue given shapes and two pink segments.
Minimum spanning tree of a circle, square, and triangle
When \(C\) is a finite point set, \(T_C\) is just a Euclidean minimum spanning tree. When \(C\) has finitely many connected components, like the example above, \(T_C\) is again a minimum spanning tree, for the component-component distances. In the general case, \(T_C\) still has many of the familiar properties of Euclidean minimum spanning trees:
• It consists of the input and a collection of line segments connecting pairs of input points, by construction.
• It is a connected set. Topologically, this means that it cannot be covered by two disjoint open sets that both have a nonempty intersection with it. (This is different from being path-connected, a stronger property.) Any nontrivial open disjoint cover of \(C\) would be spanned by a line segment from one set to the other, and no new disjoint covers can separate these line segments from their endpoints.
• For any added segment \(s_A\), the intersection of two disks with that segment as radius (a “lune”) has no point of \(C\) in its interior. Any interior point would form one end of a shorter connecting segment between \(A\) and \(C\setminus A\), with the other end at an endpoint of \(s_A\). No two added segments can cross without violating the empty lune property.
The empty lune of an edge
• For any added segment \(s_A\), the open rhombus with angles \(60^\circ\) and \(120^\circ\) having \(s_A\) as its long diagonal is disjoint from the rhombi formed in the same way from the other segments. Any two overlapping rhombi would allow the longer of the two segments they come from to be replaced by a shorter segment crossing the same compact partition, on a three-segment path connecting its endpoints via the other segment endpoints. Because these non-overlapping rhombi cover a region of bounded area, the squared segment lengths have a bounded sum, and only finitely many segments can be longer than any given length threshold.
An infinite minimum spanning tree and its empty rhombi
• The union of \(C\) with any subset of added segments is compact. If \(p\) is a limit point of a sequence \(\sigma_i\) of points in this union, it must either lie in the empty rhombus of a segment (in which case it can only be a point of the same segment), or it is a limit point of a sequence of points in \(C\), obtained by replacing each point in \(\sigma_i\) that is interior to a segment by the nearest segment endpoint. This replacement only increases the distance from the replaced point to \(p\) by a constant factor, which does not affect convergence. By compactness the replaced sequence converges to a point in \(C\).
• For any \(i\), the set \(T_i\) of the largest \(i\) added segments (with the same tie-breaking order) are edges of a minimum spanning tree for a family of \(i-1\) sets. To construct these sets, find the components of the union of \(C\) with all shorter segments, and intersect each component with \(C\). None of these components can cross between \(A\) and \(C\setminus A\) for any edge \(s_A\in T_i\). Because adding \(T_i\) connects all these components, there can be at most \(i-1\) components. Each edge in \(T_i\) is shortest (with a consistent tie-breaking rule) across some partition of the components, one of the ways of determining the edges in a finite minimum spanning tree. In particular, \(T_C\) is minimally connected: removing any edge \(s_A\in S_i\) separates some of the components from each other.
• \(T_C\) has the minimum sum of squared edge lengths of all collections of line segments between points of \(C\) that connect \(C\). To see this, consider any other connecting set \(X\) of line segments with a finite sum of squared edge lengths. Truncate the sorted sequence of edges of \(T_C\) to a finite initial sequence \(T_i\) such that the rest of the sequence has negligible sum of squares. Because \(T_i\) is a minimum spanning tree of its components, and \(X\) connects those same components (perhaps redundantly), the sequence of edge lengths in \(T_i\) is, step for step, less than or equal to the sorted sequence of lengths in \(X\).
There may exist other sets of line segments that connect \(C\) with the same sum of squared edge lengths but they all are minimally connected, with the same sequence of edge lengths, the same empty lune and empty rhombus properties, and the same property that their initial sequences form finite minimum spanning trees of their components.
(Discuss on Mastodon)
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How Animals Treat Themselves Different Methods
How Animals Treat Themselves
Let’s see that animals of the world can treat themselves by different methods.
He was a bird that was taught in the grill of the thorny wires, he tries to be free her butt cant, in this effort to get the rid of them he becomes injured. A boy was saw him from outside now boys comes and caught him and takes his home with carefully and mercifully to help them. Boy does necessary treatment free them that bird can fly now. The bird goes and set in the tree and bird opens strip wound around hair and remains open. The birds make their treatment from the sun shining. I reached the point that birds can treatment by self and they have ideas that how to treat their injuries. They make their treat himself and like humans they don’t need doctors.
Animal-treatment-methods
Animal-treatment-methods
Injured mountain rates protect them gonad of the trees to escape from germs and dust, similarly bear animal protect their injuries by using water and gonad of the trees to prevent from big injuries. According to experts if the bone of “ud ud” bird broken he takes paste in the injured place and after some days plaster is perfectly fine.
When wild animals in injured, they change their place and takes the peaceful place where they takes rest and eats verity of herbs as medicine. Lion and other wild animals when injured or ill leave to eating meat and eats only vegetables and different herbals in the treatment of different diseases which can benefit.
This point teaches us that basic medicine learning gives humans by animals.
Leaves of certain plants, such as after a losing virginity Mongoose snake venom which is capable of decoupling, When your children on rainy days (to protect it from weather conditions) find grass and fodder, Monkey ‘soon’ diseases have been seen eating neem leaves are broken off.
When wild animals are suffering from fever is people land at a place that not only shade but also clean the air and water is near. To reduce fever or fever to break some not eat, drink only water. Similar joint or muscle pains the animals that reside in a place where the sun light directly affects.
At last the old bear and other animal’s find the hot springs and the baths are regularly go there. Lice or flea dirt animals in case they are seen at the lutnyan. This process, bath Khaki ‘hyn.mahryn could also correspond to the observation of animal foods change with seasonal changes.
Injured when part of a zero chance of recovery if the doctor was forced to cut it so that other body parts are protected from risk, Will surely surprise you to know that animals are of the last treatment. If they are dealing with a situation irreversible organ are isolated from the body in different ways.
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Transparency and patterned drawing
256-color transparency
In paletted video modes, translucency and lighting are implemented with a 64k lookup table, which contains the result of combining any two colors c1 and c2. You must set up this table before you use any of the translucency or lighting routines. Depending on how you construct the table, a range of different effects are possible. For example, translucency can be implemented by using a color halfway between c1 and c2 as the result of the combination. Lighting is achieved by treating one of the colors as a light level (0-255) rather than a color, and setting up the table appropriately. A range of specialised effects are possible, for instance replacing any color with any other color and making individual source or destination colors completely solid or invisible. Color mapping tables can be precalculated with the colormap utility, or generated at runtime. Read chapter "Structures and types defined by Allegro" for an internal description of the COLOR_MAP structure.
Truecolor transparency
In truecolor video modes, translucency and lighting are implemented by a blender function of the form:
unsigned long (*BLENDER_FUNC)(unsigned long x, y, n);
For each pixel to be drawn, this routine is passed two color parameters x and y, decomposes them into their red, green and blue components, combines them according to some mathematical transformation involving the interpolation factor n, and then merges the result back into a single return color value, which will be used to draw the pixel onto the destination bitmap.
The parameter x represents the blending modifier color and the parameter y represents the base color to be modified. The interpolation factor n is in the range [0-255] and controls the solidity of the blending.
When a translucent drawing function is used, x is the color of the source, y is the color of the bitmap being drawn onto and n is the alpha level that was passed to the function that sets the blending mode (the RGB triplet that was passed to this function is not taken into account).
When a lit sprite drawing function is used, x is the color represented by the RGB triplet that was passed to the function that sets the blending mode (the alpha level that was passed to this function is not taken into account), y is the color of the sprite and n is the alpha level that was passed to the drawing function itself.
Since these routines may be used from various different color depths, there are three such callbacks, one for use with 15-bit 5.5.5 pixels, one for 16 bit 5.6.5 pixels, and one for 24-bit 8.8.8 pixels (this can be shared between the 24 and 32-bit code since the bit packing is the same).
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How To Get Rid Of Chest Fat
Lifting, pushing, and controlling arm movements all rely on the chest muscles. However, excess fat can still form in this area of the body, and some people may wonder how to get rid of chest fat. In most cases, chest fat develops as a result of having too much body fat in general. However, chest fat can develop as a result of a medical condition.
Many people experience sarcopenia as they age, which is a gradual loss of muscle tissue. A person with sarcopenia has more body fat than someone who does not have the condition.
Hormonal changes in females can cause breast growth. Anyone who notices any unusual changes or lumps in their breasts should consult a doctor. Gynecomastia, or an increase in breast gland tissue, is one possible cause of male chest fat. Males and females both have breast glands, but males’ glands are typically smaller. Gynecomastia can be caused by hormonal imbalances, obesity, or ageing.
Get Rid Of Chest Fat With Bodybuilding
Get Rid Of Chest Fat With Bodybuilding
Fat in the chest area should not always be confused with gynecomastia, a medical condition characterised by the growth of excess breast tissue rather than fat tissue in men. Excess fat on your chest and other areas can only be removed through exercise and a healthy diet. You can follow these steps to get rid of chest fat:
• Begin dieting early. Even during the off-season, it’s a good idea to keep a close eye on what you eat, but if you have a competition coming up, start your diet at least 16 weeks before the contest date. Make sure it’s a well-balanced diet rich in protein and low in fat, with plenty of whole grains, fresh fruits and vegetables. Egg whites, oatmeal, fresh fruit, chicken or lean ground beef, whole-grain pasta, steamed fresh vegetables, cottage cheese, and whole-grain bread are all recommended as six meals per day. A protein shake should also be included in one or two of the six meals.
• Focus your chest training day on pec-specific exercises like bench press (flat and incline), Smith Machine incline presses, dumbbell flys, dumbbell decline presses, dips, cable crossovers, and a pec deck workout.
• Include cardio exercise in your workout routine. To help burn off excess fat from your pecs, perform cardio exercises such as running, rowing, stair-stepping, or elliptical training for 30 minutes up to four times per week.
• To incorporate cardio with your strength training, perform your resistance workout as a circuit. Circuit workouts, according to personal trainer and former bodybuilder Matt Siaperas, save time by allowing you to get fat-burning aerobic exercise while also working your muscles with resistance. Perform only one set of each exercise during your workout, moving from exercise to exercise with no rest in between.
Get Rid Of Chest Fat With Surgery
Get Rid Of Chest Fat With Surgery
If you can’t get rid of chest fat despite initial treatment or observation, your doctor may recommend surgery.
There are two gynecomastia surgery options:
• Liposuction: This procedure removes breast fat but not breast gland tissue.
• Mastectomy: The breast gland tissue is removed during this type of surgery. Small incisions are frequently used in surgery. This less invasive type of surgery has a shorter recovery period.
Get Rid Of Chest Fat Naturally
Get Rid Of Chest Fat Naturally
Losing chest fat is no different than losing fat anywhere else on your body, and there is no way to lose fat from your chest alone. It is part of total-body fat loss. If you want to tone up your pecs, here’s how fat loss works.
To lose one pound of fat, you must burn 3,500 calories. It’s all math, specifically the Forbes equation. A caloric deficit can be achieved through diet, exercise, or both.
Most of us consume between 1,800 and 3,000 calories per day. You don’t have to make any drastic changes. Dropping 500 calories from your daily intake results in a weekly weight loss of one pound, and those pounds add up quickly. You’ll be down nearly 10 pounds after two months. The key to success is consistency: Making small changes on a daily basis always yields better, longer-lasting results than starving yourself or crash dieting.
Keto Diet
The keto diet can be especially effective if you want to go all-in on low carb. A keto diet is essentially a very low carb diet in which carbs are limited to 50 grammes or less per day, with moderate protein and relatively high fat intake. While eating fat to lose fat may seem counterintuitive, fats and proteins can satisfy hunger, causing you to eat less overall. The goal of the keto diet is to get your body into ketosis, a state in which it burns fat for fuel instead of carbs — but only after it has used up any stored sugar in your liver and muscles. If you have trouble with moderation, it might be a good idea to track your calories. There’s an app for that, just like there’s an app for everything these days.
Exercises
Bench press
For this exercise, you’ll need weights and a bench. To avoid injury, start light and gradually increase your weight — don’t be a hero. In this description, we’ll use a barbell, but you can also do this exercise with dumbbells.
Lie on a workout bench with your back flat and the bar against your chest. Maintain a shoulder-width distance between your hands. Slowly press the bar up until your arms are straight but not locked. Keep your elbows at a 45-degree angle as you lower the bar back down. Allow the bar to brush against your body before pressing it back up.
Push-Ups
The good old-fashioned push-up — no weights needed and extremely effective.
To perform a proper push-up, begin in a plank position with your hands under your shoulders and your feet shoulder-width apart. As you slowly lower to the floor, keep your arms tight to your body. Raise your body by pressing your palms into the floor. Repeat, attempting to increase the number of reps each time you exercise.
Dumbbell pull-over
You’ll need a set of dumbbells and a bench for this exercise. Begin by lying completely flat on the bench. Hold the dumbbells straight up, over your chest — the dumbbells should be parallel to the floor. Keep your thumb tightly wrapped around the bar for your own safety. Nobody enjoys getting a dumbbell to the head. Slowly lower the weights over your head toward the floor, but don’t go past your ears. Then, return them to the starting position. Repeat. Remember to start with lighter weights and work your way up. There’s no shame in asking someone to spot you.
Cable cross
A cable cross can be performed on a machine at the gym or at home with exercise bands. The cable cross identifies the area of your chest beneath your arms, near your armpits. If you’re using a machine, adjust the weight to achieve the desired resistance. It’s best to do as many reps as you can with a lighter weight for tightening and firming. Begin by keeping your hips square and your back to the machine. Pull the handles towards you until they intersect and form an X.
Cardio Exercises
It’s probably safe to say that no one enjoys cardio, but if you want to cut calories and burn fat, it’s in your best interest to kiss and make up. Aim for 20 to 40 minutes four times a week for best results. On the bright side, when it comes to cardio, the world is essentially your oyster. Among the best options are:
• Biking
• Elliptical
• stair-climber
• jumping rope
• running at a medium pace (outside or on a treadmill)
Swimming
Swimming can be a great way to lose excess chest fat and tone up the upper body. It is especially beneficial for women who want to lose breast fat. It works out the chest muscles quickly and effectively. If you can spend an hour a day in the pool without taking more than a 2-5 minute break, you can easily lose chest fat in a month.
Yogas
Dhanurasana
Dhanurasana, also known as the Bow pose, can help women lose chest fat. To perform this asana, lie on your stomach on the floor and lift your legs upward and backwards, folding them from the knees. Move your upper body in an upward and backward motion. To complete the pose, hold your feet with your hands for at least 30 seconds.
Balasana
Women can easily perform Balasana, or the resting child’s pose, to reap the benefits of reduced chest fat. Place your legs under your hips and sit on the floor. Your hips should be completely supported by your legs, and your body should be well balanced. Now, lower your head until it touches the ground. Take your hands back to hold your feet’s ankles once you’ve touched the ground. Hold the pose for 30-40 seconds before relaxing.
Ustrasana
Ustrasana, or the camel pose, can also help women lose chest fat. On your knees, stand on the yoga mat. Your hip should not be supported by your legs. Maintain your torso erect at first, then slowly bend backwards and grasp the ankles of your legs with your hands as shown in the picture. Hold this position for 30 seconds before releasing.
Natarajasana
Natarajasana, also known as the Lord of Dance Pose, is an advanced level yogasana that should not be attempted by beginners. To perform this pose, stand on one leg and then raise your other leg upwards and backwards, as shown in the image above, to hold it with your hands.
How To Get Rid Of Chest Fat Under Arms?
To tone your underarms try to do these exercises:
• Push-up
• Cat-cow
• Downward facing dog
• Triceps press
• Triceps extension
• Chest press
• Bicep curl
• Bench dip
• Triceps press-down
• Seated row
Get Rid Of Chest Fat Reddit
There has been a lot of discussion about how to get rid of chest fat on Reddit. Mainly it says that there is no such thing as spot fat reduction. You should work chest exercises (bench press, flys, etc.) to build a muscle foundation so that skin and fat fall in a more flattering manner. Also, work on your back and shoulders as well. It appears to tighten things up a little more. Losing weight will only make a minor difference. Most people lose a similar proportion of muscle and fat when they lose weight. As a result, your proportions will look very similar, albeit smaller. Lifting weights is the solution. Instead of losing muscle, you will gain muscle. You don’t want to just burn fat and muscle. You want to lose fat while building muscle. As a result, your muscle-to-fat ratio improves (more muscle, less fat).
This is the only way to get rid of chest fat. This would be extremely difficult to accomplish using cardio (running, swimming, sports, etc.) Diet is also extremely important. In fact, it is more important than physical activity. Consume fewer calories and eat healthier. You will lose both fat and muscle if you only do cardio. So you’ll be much smaller, with less fat in the stomach, but you’ll still have chest fat, even if the rest of your body is skinny. That is why it is critical that you exercise with weights. You can also do bodyweight exercises, such as push-ups. However, it must be resistance training rather than cardio. Cardio can be done in addition to resistance training. However, don’t make cardio your primary focus. Weights and diet are the main ways to get rid of chest fat.
How To Get Rid Of Chest Fat As Teenager?
If you want to lose chest fat, you must lose fat all over your body. Fat cannot be removed from a single location. Begin by eating fewer calories than your maintenance calories. Sleep for at least 7-8 hours. Incorporate compound movements into your workout as well. Leg days should never be skipped. You can speed up the fat-loss process by including cardio. Begin doing push-ups and pull-ups at home. If you are doing it for the first time, don’t be afraid to try it. Make a habit of doing push-ups every day; after a while, you will notice results, but don’t expect them to come quickly. It takes time, and you should also consider your diet. Perform a variety of exercises if possible. Liposuction is the only way to lose fat in a week. If you have the time, go to the gym and work out.
How To Get Rid Of Chest Fat For Females?
Look for a Calorie-Restricted Diet
When attempting to lose body fat, you must rely on a regular diet that provides fewer calories while keeping your stomach full. The best way to plan such a diet is to include more vegetables and fruits in your diet because fruits and vegetables are high in vitamins, minerals, and dietary fibres while being low in calories. The best thing about dietary fibres is that they keep you fuller for longer while adding a few calories to your diet. So, if you want to lose excess chest fat, include more of these foods in your daily diet.
Avoiding Fats and Junk Food
Foods high in fat and junk food are two of the primary causes of rising obesity rates in every society. Fats, particularly saturated fats, are the most dangerous enemy of a fit body. They raise cholesterol levels in the blood and are the primary cause of fat deposition. As a result, avoid all fatty foods, such as butter, cheese, ghee, and oils. Colas, even diet colas, chips, and other high-calorie foods should be avoided. Deep-fried foods should be avoided at all costs, at least for the time being. Make an effort to reduce your consumption of junk foods, which may be tasty but are harmful to your health.
How to Get Rid of Side Fat
Keep an eye on your sugar and carbohydrate intake. The amount of sugar and carbohydrate you consume on a daily basis has a direct impact on your body weight. Instead of being burned during metabolism, sugars and carbohydrates are easily stored in the body. So, take a look at how much sugar and carbohydrate you consume on a daily basis. Avoid giving in to your sweet tooth. If you have a strong desire for sweets, opt for fresh sweet fruits rather than a pastry or ice cream.
Reduce Your Alcohol Consumption
Alcohol is one of the primary causes of alcoholic fat in the body, which is notoriously difficult to burn off. If you drink and have excess chest fat, the first thing you should do for your health is to stop drinking. Apart from adhering to the aforementioned rules when deciding on a diet, keep the following guidelines in mind to ensure that what you eat is properly used in the body during metabolism rather than being stored.
Get Rid Of Chest Fat FAQs
Get Rid Of Chest Fat
Can you get rid of chest fat easily?
It takes time to get results from your exercise. However, it is definitely possible to see the results within a month or two.
What are some exercises I could do at home to get rid of chest fat?
You can try pushups and a couple of yoga positions like Dhanurasana and Ustrasana to get rid of chest fat.
Is it safe to get liposuction to get rid of chest fat?
Liposuction is an option to get rid of chest fat. However, you can try working out first.
Is Keto diet effective in getting rid of chest fat?
Yes, Keto diet is very effective. But, consult a nutritionist first.
How many calories do I need to burn every day to get rid of chest fat?
You need to burn about 3500 calories each day to get rid of chest fat.
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Water (molecule)
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Water (H2O, HOH) is the most abundant molecule on Earth's surface, composing of about 70% of the Earth's surface as liquid and solid state in addition to being found in the atmosphere as a vapor. It is in dynamic equilibrium between the liquid and vapor states at standard temperature and pressure. At room temperature, it is a nearly colorless, tasteless, and odorless liquid, with a hint of blue. Many substances dissolve in water and it is commonly referred to as the universal solvent. Because of this, water in nature and in use is rarely clean, and may have some properties different from those in the laboratory. However, there are many compounds that are essentially, if not completely, insoluble in water. Water is the only common, pure substance found naturally in all three common states of matter—for other substances, see Chemical properties.
Forms of water
See the Water#Overview of types of water
Water can take many forms. The solid state of water is commonly known as ice (while many other forms exist; see amorphous solid water); the gaseous state is known as water vapor (or steam, though this is actually incorrect, since steam is just condensing liquid water droplets), and the common liquid phase is generally taken as simply water. Above a certain critical temperature and pressure (647 K and 22.064 MPa), water molecules assume a supercritical condition, in which liquid-like clusters float within a vapor-like phase.
Heavy water is water in which the hydrogen is replaced by its heavier isotope, deuterium. It is chemically almost identical to normal water. Heavy water is used in the nuclear industry to slow down neutrons.
Physics and chemistry of water
Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Water is a tasteless, odorless liquid at ambient temperature and pressure, and appears colorless in small quantities, although it has its own intrinsic very light blue hue. Ice also appears colorless, and water vapor is essentially invisible as a gas.[1] Water is primarily a liquid under standard conditions, which is not predicted from its relationship to other analogous hydrides of the oxygen family in the periodic table, which are gases such as hydrogen sulfide. Also the elements surrounding oxygen in the periodic table, nitrogen, fluorine, phosphorus, sulfur and chlorine, all combine with hydrogen to produce gases under standard conditions. The reason that oxygen hydride (water) forms a liquid is that it is more electronegative than all of these elements (other than fluorine). Oxygen attracts electrons much more strongly than hydrogen, resulting in a net positive charge on the hydrogen atoms, and a net negative charge on the oxygen atom. The presence of a charge on each of these atoms gives each water molecule a net dipole moment. Electrical attraction between water molecules due to this dipole pulls individual molecules closer together, making it more difficult to separate the molecules and therefore raising the boiling point. This attraction is known as hydrogen bonding. Water can be described as a polar liquid that dissociates disproportionately into the hydronium ion (H3O+(aq)) and an associated hydroxide ion (OH(aq)). Water is in dynamic equilibrium between the liquid, gas and solid states at standard temperature and pressure, and is the only pure substance found naturally on Earth to be so.
Water, ice and vapor
Heat capacity and heat of vaporization
Water has the second highest specific heat capacity of any known chemical compound, after ammonia, as well as a high heat of vaporization (40.65 kJ mol−1), both of which are a result of the extensive hydrogen bonding between its molecules. These two unusual properties allow water to moderate Earth's climate by buffering large fluctuations in temperature.
Density of water and ice
The solid form of most substances is more dense than the liquid phase; thus, a block of pure solid substance will sink in a tub of pure liquid substance. But, by contrast, a block of common ice will float in a tub of water because solid water is less dense than liquid water. This is an extremely important characteristic property of water. At room temperature, liquid water becomes denser with lowering temperature, just like other substances. But at 4 °C, just above freezing, water reaches its maximum density, and as water cools further toward its freezing point, the liquid water, under standard conditions, expands to become less dense. The physical reason for this is related to the crystal structure of ordinary ice, known as hexagonal ice Ih. Water, lead, uranium, neon and silicon are some of the few materials which expand when they freeze; most other materials contract. It should be noted however, that not all forms of ice are less dense than liquid water. For example HDA and VHDA are both more dense than liquid phase pure water. Thus, the reason that the common form of ice is less dense than water is a bit non-intuitive and relies heavily on the unusual properties inherent to the hydrogen bond.
Generally, water expands when it freezes because of its molecular structure, in tandem with the unusual elasticity of the hydrogen bond and the particular lowest energy hexagonal crystal conformation that it adopts under standard conditions. That is, when water cools, it tries to stack in a crystalline lattice configuration that stretches the rotational and vibrational components of the bond, so that the effect is that each molecule of water is pushed further from each of its neighboring molecules. This effectively reduces the density ρ of water when ice is formed under standard conditions.
The importance of this property cannot be overemphasized for its role on the ecosystem of Earth. For example, if water were more dense when frozen, lakes and oceans in a polar environment would eventually freeze solid (from top to bottom). This would happen because frozen ice would settle on the lake and riverbeds, and the necessary warming phenomenon (see below) could not occur in summer, as the warm surface layer would be less dense than the solid frozen layer below. It is a significant feature of nature that this does not occur naturally in the environment.
Nevertheless, the unusual expansion of freezing water (in ordinary natural settings in relevant biological systems), due to the hydrogen bond, from 4 °C above freezing to the freezing point offers an important advantage for freshwater life in winter. Water chilled at the surface increases in density and sinks, forming convection currents that cool the whole water body, but when the temperature of the lake water reaches 4 °C, water on the surface decreases in density as it chills further and remains as a surface layer which eventually freezes and forms ice. Since downward convection of colder water is blocked by the density change, any large body of fresh water frozen in winter will have the coldest water near the surface, away from the riverbed or lakebed. This accounts for various little known phenomena of ice characteristics as they relate to ice in lakes and "ice falling out of lakes" as described by early 20th century scientist Horatio D. Craft.
The following table gives the density of water in grams per cubic centimeter at various temperatures in degrees Celsius:[2]
Temp (°C) Density (g/cm³)
30 0.9956502
25 0.9970479
22 0.9977735
20 0.9982071
15 0.9991026
10 0.9997026
4 0.9999720
0 0.9998395
−10 0.998117
−20 0.993547
−30 0.983854
The values below 0 °C refer to supercooled water.
Freezing point
A simple but environmentally important and unusual property of water is that its usual solid form, ice, floats on its liquid form. This solid state is not as dense as liquid water because of the geometry of the hydrogen bonds which are formed only at lower temperatures. For almost all other substances the solid form has a greater density than the liquid form. Fresh water at standard atmospheric pressure is most dense at 3.98 °C, and will sink by convection as it cools to that temperature, and if it becomes colder it will rise instead. This reversal will cause deep water to remain warmer than shallower freezing water, so that ice in a body of water will form first at the surface and progress downward, while the majority of the water underneath will hold a constant 4 °C. This effectively insulates a lake floor from the cold. The water will freeze at 0 °C (32 °F, 273 K), however, it can be supercooled in a fluid state down to its crystal homogeneous nucleation at almost 231 K (−42 °C)[3]. Ice also has a number of more exotic phases not commonly seen (go to the full article on Ice).
Density of saltwater and ice
The density of water is dependent on the dissolved salt content as well as the temperature of the water. Ice still floats in the oceans, otherwise they would freeze from the bottom up. However, the salt content of oceans lowers the freezing point by about 2 °C and lowers the temperature of the density maximum of water to the freezing point. That is why, in ocean water, the downward convection of colder water is not blocked by an expansion of water as it becomes colder near the freezing point. The oceans' cold water near the freezing point continues to sink. For this reason, any creature attempting to survive at the bottom of such cold water as the Arctic Ocean generally lives in water that is 4 °C colder than the temperature at the bottom of frozen-over fresh water lakes and rivers in the winter.
As the surface of salt water begins to freeze (at −1.9 °C for normal salinity seawater, 3.5%) the ice that forms is essentially salt free with a density approximately equal to that of freshwater ice. This ice floats on the surface and the salt that is "frozen out" adds to the salinity and density of the seawater just below it, in a process known as brine rejection. This more dense saltwater sinks by convection and the replacing seawater is subject to the same process. This provides essentially freshwater ice at −1.9 °C on the surface. The increased density of the seawater beneath the forming ice causes it to sink towards the bottom.
Miscibility and condensation
Water is miscible with many liquids, for example ethanol in all proportions, forming a single homogeneous liquid. On the other hand water and most oils are immiscible usually forming layers according to increasing density from the top.
Red line shows saturation
As a gas, water vapor is completely miscible with air. On the other hand the maximum water vapor pressure that is thermodynamically stable with the liquid (or solid) at a given temperature is relatively low compared with total atmospheric pressure. For example, if the vapor partial pressure[4] is 2% of atmospheric pressure and the air is cooled from 25 °C, starting at about 22 °C water will start to condense, defining the dew point, and creating fog or dew. The reverse process accounts for the fog burning off in the morning. If one raises the humidity at room temperature, say by running a hot shower or a bath, and the temperature stays about the same, the vapor soon reaches the pressure for phase change, and condenses out as steam. A gas in this context is referred to as saturated or 100% relative humidity, when the vapor pressure of water in the air is at the equilibrium with vapor pressure due to (liquid) water; water (or ice, if cool enough) will fail to lose mass through evaporation when exposed to saturated air. Because the amount of water vapor in air is small, relative humidity, the ratio of the partial pressure due to the water vapor to the saturated partial vapor pressure, is much more useful. Water vapor pressure above 100% relative humidity is called super-saturated and can occur if air is rapidly cooled, say by rising suddenly in an updraft.[5]
Vapor Pressures of Water
Temperature (°C) Pressure (torr)
0 4.58
5 6.54
10 9.21
12 10.52
14 11.99
16 13.63
17 14.53
18 15.48
19 16.48
20 17.54
21 18.65
22 19.83
23 21.07
24 22.38
25 23.76
[6]
Compressibility
The compressibility of water is a function of pressure and temperature. At 0 °C in the limit of zero pressure the compressibility is 5.1×10-5 bar−1.[7] In the zero pressure limit the compressibility reaches a minimum of 4.4×10-5 bar−1 around 45 °C before increasing again with increasing temperature. As the pressure is increased the compressibility decreases, being 3.9×10-5 bar−1 at 0 °C and 1000 bar. The bulk modulus of water is 2.2×109 Pa.[8] The low compressibility of non-gases, and of water in particular, leads to them often being assumed as incompressible. The low compressibility of water means that even in the deep oceans at 4000 m depth, where pressures are 4×107 Pa, there is only a 1.8% decrease in volume.[8]
Triple point
The various triple points of water[9]
Phases in stable equilibrium Pressure Temperature
liquid water, ice I, and water vapour 611.73 Pa 273.16 K
liquid water, ice Ih, and ice III 209.9 MPa 251 K (-22 °C)
liquid water, ice Ih, and gaseous water 612 Pa 0.01 °C
liquid water, ice III, and ice V 350.1 MPa -17.0 °C
liquid water, ice V, and ice VI 632.4 MPa 0.16 °C
ice Ih, Ice II, and ice III 213 MPa -35 °C
ice II, ice III, and ice V 344 MPa -24 °C
ice II, ice V, and ice VI 626 MPa -70 °C
The temperature and pressure at which solid, liquid, and gaseous water coexist in equilibrium is called the triple point of water. This point is used to define the units of temperature (the kelvin and, indirectly, the degree Celsius and even the degree Fahrenheit). The triple point is at a temperature of 273.16 K (0.01 °C) by convention, and at a pressure of 611.73 Pa. This pressure is quite low, about 1/166 of the normal sea level barometric pressure of 101,325 Pa. The atmospheric surface pressure on planet Mars is remarkably close to the triple point pressure, and the zero-elevation or "sea level" of Mars is defined by the height at which the atmospheric pressure corresponds to the triple point of water.
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water phase diagram
Y-axis = Pressure in Pascal (10n),
X-axis = Temperature in Kelvin.
S = Solid
L = Liquid
V = Vapour
CP = Critical Point
TP = Triple point of water
The triple point of water (the single combination of pressure and temperature at which pure liquid water, ice, and water vapor can coexist in a stable equilibrium) is used to define the kelvin, the SI unit of thermodynamic temperature. As a consequence, water's triple point temperature is a prescribed value rather than a measured quantity: 273.16 kelvins (0.01 °C) and a pressure of 611.73 pascals (approximately 0.0060373 atm). This is approximately the combination that exists with 100% relative humidity at sea level and the freezing point of water.
Although it is commonly named as "the triple point of water", the stable combination of liquid water, ice I, and water vapour is but one of several triple points on the phase diagram of water. Gustav Heinrich Johann Apollon Tammann in Göttingen produced data on several other triple points in the early 20th century. Kamb and others documented further triple points in the 1960s.[10][9][11]
Mpemba effect
The Mpemba effect is the surprising phenomenon whereby hot water can, under certain conditions, freeze sooner than cold water, even though it must pass the lower temperature on the way to freezing. However, this can be explained with evaporation, convection, supercooling, and the insulating effect of frost.
Hot ice
Hot ice is the name given to another surprising phenomenon in which water at room temperature can be turned into ice that remains at room temperature by supplying an electric field on the order of 106 volts per meter.[12]
The effect of such electric fields has been suggested as an explanation of cloud formation. The first time cloud ice forms around a clay particle, it requires a temperature of −10 °C, but subsequent freezing around the same clay particle requires a temperature of just −5 °C, suggesting some kind of structural change.[13]
Surface tension
Water drops are stable, due to the high surface tension of water, 72.8 mN/m, the highest of the non-metallic liquids. This can be seen when small quantities of water are put on a surface such as glass: the water stays together as drops. This property is important for life. For example, when water is carried through xylem up stems in plants the strong intermolecular attractions hold the water column together. Strong cohesive properties hold the water column together, and strong adhesive properties stick the water to the xylem, and prevent tension rupture caused by transpiration pull. Other liquids with lower surface tension would have a higher tendency to "rip", forming vacuum or air pockets and rendering the xylem water transport inoperative.
Electrical properties
Pure water containing no ions is an excellent insulator, however, not even "deionized" water, is completely free of ions. Water undergoes auto-ionisation at any temperature above absolute zero. Further, because water is such a good solvent, it almost always has some solute dissolved in it, most frequently a salt. If water has even a tiny amount of such an impurity, then it can conduct electricity readily, as impurities such as salt separate into free ions in aqueous solution by which an electric current can flow.
Water can be split into its constituent elements, hydrogen and oxygen, by passing a current through it. This process is called electrolysis. Water molecules naturally dissociate into H+ and OH ions, which are pulled toward the cathode and anode, respectively. At the cathode, two H+ ions pick up electrons and form H2 gas. At the anode, four OH ions combine and release O2 gas, molecular water, and four electrons. The gases produced bubble to the surface, where they can be collected. It is known that the theoretical maximum electrical resistivity for water is approximately 182 ·m²/m (or 18.2 MΩ·cm²/cm) at 25 °C. This figure agrees well with what is typically seen on reverse osmosis, ultrafiltered and deionized ultrapure water systems used for instance, in semiconductor manufacturing plants. A salt or acid contaminant level exceeding that of even 100 parts per trillion (ppt) in ultrapure water will begin to noticeably lower its resistivity level by up to several kilohm-square meters per meter (a change of several hundred nanosiemens per meter of conductance).
Electrical conductivity
Pure water has a low electrical conductivity, but this increases significantly upon solvation of a small amount of ionic material water such as hydrogen chloride. Thus the risks of electrocution are much greater in water with the usual impurities not found in pure water. Any electrical properties observable in water are from the ions of mineral salts and carbon dioxide dissolved in it. Water does self-ionize where two water molecules become one hydroxide anion and one hydronium cation, but not enough to carry enough electric current to do any work or harm for most operations. In pure water, sensitive equipment can detect a very slight electrical conductivity of 0.055 µS/cm at 25 °C. Water can also be electrolyzed into oxygen and hydrogen gases but in the absence of dissolved ions this is a very slow process, as very little current is conducted. While electrons are the primary charge carriers in water (and metals), in ice (and some other electrolytes), protons are the primary carriers (see proton conductor).
Dipolar nature of water
model of hydrogen bonds between molecules of water
An important feature of water is its polar nature. The water molecule forms an angle, with hydrogen atoms at the tips and oxygen at the vertex. Since oxygen has a higher electronegativity than hydrogen, the side of the molecule with the oxygen atom has a partial negative charge. A molecule with such a charge difference is called a dipole. The charge differences cause water molecules to be attracted to each other (the relatively positive areas being attracted to the relatively negative areas) and to other polar molecules. This attraction is known as hydrogen bonding, and explains many of the properties of water. Certain molecules, such as carbon dioxide, also have a difference in electronegativity between the atoms but the difference is that the shape of carbon dioxide is symmetrically aligned and so the opposing charges cancel one another out. This phenomenon of water can be seen if you hold an electrical source near a thin stream of water falling vertically, causing the stream to bend towards the electrical source.
Although hydrogen bonding is a relatively weak attraction compared to the covalent bonds within the water molecule itself, it is responsible for a number of water's physical properties. One such property is its relatively high melting and boiling point temperatures; more heat energy is required to break the hydrogen bonds between molecules. The similar compound hydrogen sulfide (H2S), which has much weaker hydrogen bonding, is a gas at room temperature even though it has twice the molecular mass of water. The extra bonding between water molecules also gives liquid water a large specific heat capacity. This high heat capacity makes water a good heat storage medium.
Hydrogen bonding also gives water its unusual behavior when freezing. When cooled to near freezing point, the presence of hydrogen bonds means that the molecules, as they rearrange to minimize their energy, form the hexagonal crystal structure of ice that is actually of lower density: hence the solid form, ice, will float in water. In other words, water expands as it freezes, whereas almost all other materials shrink on solidification.
An interesting consequence of the solid having a lower density than the liquid is that ice will melt if sufficient pressure is applied. With increasing pressure the melting point temperature drops and when the melting point temperature is lower than the ambient temperature the ice begins to melt. A significant increase of pressure is required to lower the melting point temperature —the pressure exerted by an ice skater on the ice would only reduce the melting point by approximately 0.09 °C (0.16 °F).
Electronegative Polarity
Water has a partial negative charge (σ-) near the oxygen atom due to the unshared pairs of electrons, and partial positive charges (σ+) near the hydrogen atoms. In water, this happens because the oxygen atom is more electronegative than the hydrogen atoms — that is, it has a stronger "pulling power" on the molecule's electrons, drawing them closer (along with their negative charge) and making the area around the oxygen atom more negative than the area around both of the hydrogen atoms.
Adhesion
Dew drops adhering to a spider web
Water sticks to itself (cohesion) because it is polar. Water also has high adhesion properties because of its polar nature. On extremely clean/smooth glass the water may form a thin film because the molecular forces between glass and water molecules (adhesive forces) are stronger than the cohesive forces. In biological cells and organelles, water is in contact with membrane and protein surfaces that are hydrophilic; that is, surfaces that have a strong attraction to water. Irving Langmuir observed a strong repulsive force between hydrophilic surfaces. To dehydrate hydrophilic surfaces—to remove the strongly held layers of water of hydration—requires doing substantial work against these forces, called hydration forces. These forces are very large but decrease rapidly over a nanometer or less. Their importance in biology has been extensively studied by V. Adrian Parsegian of the National Institute of Health.[14] They are particularly important when cells are dehydrated by exposure to dry atmospheres or to extracellular freezing.
Surface tension
This daisy is under the water level, which has risen gently and smoothly. Surface tension prevents the water from submerging the flower.
Water has a high surface tension caused by the strong cohesion between water molecules. This can be seen when small quantities of water are put onto a non-soluble surface such as polythene; the water stays together as drops. Just as significantly, air trapped in surface disturbances forms bubbles, which sometimes last long enough to transfer gas molecules to the water. Another surface tension effect is capillary waves which are the surface ripples that form from around the impact of drops on water surfaces, and some times occur with strong subsurface currents flow to the water surface. The apparent elasticity caused by surface tension drives the waves.
Capillary action
Capillary action refers to the process of water moving up a narrow tube against the force of gravity. It occurs because water adheres to the sides of the tube, and then surface tension tends to straighten the surface making the surface rise, and more water is pulled up through cohesion. The process is repeated as the water flows up the tube until there is enough water that gravity can counteract the adhesive force.
Water as a solvent
Water is also a good solvent due to its polarity. When an ionic or polar compound enters water, it is surrounded by water molecules (Hydration). The relatively small size of water molecules typically allows many water molecules to surround one molecule of solute. The partially negative dipole ends of the water are attracted to positively charged components of the solute, and vice versa for the positive dipole ends.
In general, ionic and polar substances such as acids, alcohols, and salts are relatively soluble in water, and nonpolar substances such as fats and oils are not. Nonpolar molecules stay together in water because it is energetically more favorable for the water molecules to hydrogen bond to each other than to engage in van der Waals interactions with nonpolar molecules.
An example of an ionic solute is table salt; the sodium chloride, NaCl, separates into Na+ cations and Cl- anions, each being surrounded by water molecules. The ions are then easily transported away from their crystalline lattice into solution. An example of a nonionic solute is table sugar. The water dipoles make hydrogen bonds with the polar regions of the sugar molecule (OH groups) and allow it to be carried away into solution.
Solvation
High concentrations of dissolved lime make the water of Havasu Falls appear turquoise.
Water is a very strong solvent, referred to as the universal solvent, dissolving many types of substances. Substances that will mix well and dissolve in water (e.g. salts) are known as "hydrophilic" (water-loving) substances, while those that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances. The ability of a substance to dissolve in water is determined by whether or not the substance can match or better the strong attractive forces that water molecules generate between other water molecules. If a substance has properties that do not allow it to overcome these strong intermolecular forces, the molecules are "pushed out" from the water, and do not dissolve. Contrary to the common misconception, water and hydrophobic substances does not "repel", and the hydration of a hydrophobic surface is energetically, but not entropically, favorable.
Amphoteric nature of water
Chemically, water is amphoteric — i.e., it is able to act as either an acid or a base. Occasionally the term hydroxic acid is used when water acts as an acid in a chemical reaction. At a pH of 7 (neutral), the concentration of hydroxide ions (OH) is equal to that of the hydronium (H3O+) or hydrogen (H+) ions. If the equilibrium is disturbed, the solution becomes acidic (higher concentration of hydronium ions) or basic (higher concentration of hydroxide ions).
Water can act as either an acid or a base in reactions. According to the Brønsted-Lowry system, an acid is defined as a species which donates a proton (an H+ ion) in a reaction, and a base as one which receives a proton. When reacting with a stronger acid, water acts as a base; when reacting with a stronger base, it acts as an acid. For instance, it receives an H+ ion from HCl in the equilibrium:
HCl + H2O Template:Unicode H3O+ + Cl
Here water is acting as a base, by receiving an H+ ion.
In the reaction with ammonia, NH3, water donates an H+ ion, and is thus acting as an acid:
NH3 + H2O Template:Unicode NH4+ + OH
Acidity in nature
In theory, pure water has a pH of 7 at 298 K. In practice, pure water is very difficult to produce. Water left exposed to air for any length of time will rapidly dissolve carbon dioxide, forming a dilute solution of carbonic acid, with a limiting pH of about 5.7. As cloud droplets form in the atmosphere and as raindrops fall through the air minor amounts of CO2 are absorbed and thus most rain is slightly acidic. If high amounts of nitrogen and sulfur oxides are present in the air, they too will dissolve into the cloud and rain drops producing more serious acid rain problems.
Hydrogen bonding in water
A water molecule can form a maximum of four hydrogen bonds because it can accept two and donate two hydrogens. Other molecules like hydrogen fluoride, ammonia, methanol form hydrogen bonds but they do not show anomalous behaviour of thermodynamic, kinetic or structural properties like those observed in water. The answer to the apparent difference between water and other hydrogen bonding liquids lies in the fact that apart from water none of the hydrogen bonding molecules can form four hydrogen bonds either due to an inability to donate/accept hydrogens or due to steric effects in bulky residues. In water local tetrahedral order due to the four hydrogen bonds gives rise to an open structure and a 3-dimensional bonding network, which exists in contrast to the closely packed structures of simple liquids. There is a great similarity between water and silica in their anomalous behaviour, even though one (water) is a liquid which has a hydrogen bonding network while the other (silica) has a covalent network with a very high melting point. One reason that water is well suited, and chosen, by life-forms, is that it exhibits its unique properties over a temperature regime that suits diverse biological processes, including hydration.
It is believed that hydrogen bond in water is largely due to electrostatic forces and some amount of covalency. The partial covalent nature of hydrogen bond predicted by Linus Pauling in the 1930s is yet to be proven unambiguously by experiments and theoretical calculations.
Quantum properties of molecular water
Although the molecular formula of water is generally considered to be a stable result in molecular thermodynamics, recent work started in 1995 has shown that at certain scales, water may act more like H3/2O than H2O at the quantum level.[15] This result could have significant ramifications at the level of, for example, the hydrogen bond in biological, chemical and physical systems. The experiment shows that when neutrons and electrons collide with water, they scatter in a way that indicates that they only are affected by a ratio of 1.5:1 of hydrogen to oxygen respectively. However, the time-scale of this response is only seen at the level of attoseconds (10-18 seconds), and so is only relevant in highly resolved kinetic and dynamical systems.[16][17]
Heavy Water and isotopologues of water
Hydrogen has three isotopes. The most common, making up more than 95% of water, has 1 proton and 0 neutrons. A second isotope, deuterium (short form "D"), has 1 proton and 1 neutron. Deuterium, D
2
O
, is also known as heavy water and is used in nuclear reactors as a neutron moderator. The third isotope, tritium, has 1 proton and 2 neutrons, and is radioactive, with a half-life of 12.32 years. T
2
O
exists in nature only in tiny quantities, being produced primarily via cosmic ray-driven nuclear reactions in the atmosphere. D
2
O
is stable, but differs from H
2
O
in in that it is more dense - hence, "heavy water" - and in that several other physical properties are slightly different from those of common, Hydrogen-1 containing "light water". D
2
O
occurs naturally in ordinary water in very low concentrations. Consumption of pure isolated D
2
O
may affect biochemical processes - ingestion of large amounts impairs kidney and central nervous system function. However, very large amounts of heavy water must be consumed for any toxicity to be apparent, and smaller quantities can be consumed with no ill effects at all.
Transparency
Water's transparency is also an important property of the liquid. If water were not transparent, sunlight, essential to aquatic plants, would not reach into seas and oceans.
History
The properties of water have historically been used to define various temperature scales. Notably, the Kelvin, Celsius and Fahrenheit scales were, or currently are, defined by the freezing and boiling points of water. The less common scales of Delisle, Newton, Réaumur and Rømer were defined similarly. The triple point of water is a more commonly used standard point today.[18]
The first scientific decomposition of water into hydrogen and oxygen, by electrolysis, was done in 1800 by William Nicholson, an English chemist. In 1805, Joseph Louis Gay-Lussac and Alexander von Humboldt showed that water is composed of two parts hydrogen and one part oxygen (by volume).
Gilbert Newton Lewis isolated the first sample of pure heavy water in 1933.
Polywater was a hypothetical polymerized form of water that was the subject of much scientific controversy during the late 1960s. The consensus now is that it does not exist.
Pseudoscience concept is water memory.
Systematic naming
The accepted IUPAC name of water is simply "water", although there are two other systematic names which can be used to describe the molecule.
The simplest and best systematic name of water is hydrogen oxide. This is analogous to related compounds such as hydrogen peroxide, hydrogen sulfide, and deuterium oxide (heavy water). Another systematic name, oxidane, is accepted by IUPAC as a parent name for the systematic naming of oxygen-based substituent groups,[19] although even these commonly have other recommended names. For example, the name hydroxyl is recommended over oxidanyl for the –OH group. The name oxane is explicitly mentioned by the IUPAC as being unsuitable for this purpose, since it is already the name of a cyclic ether also known as tetrahydropyran in the Hantzsch-Widman system; similar compounds include dioxane and trioxane.
Systematic nomenclature and humor
Dihydrogen monoxide or DHMO is an overly pedantic systematic covalent name of water. This term has been used in parodies of chemical research that call for this "lethal chemical" to be banned. In reality, a more realistic systematic name would be hydrogen oxide, since the "di-" and "mon-" prefixes are superfluous. Hydrogen sulfide, H2S, is never referred to as "dihydrogen monosulfide", and hydrogen peroxide, H2O2, is never called "dihydrogen dioxide".
Some overzealous material safety data sheets for water list the following: Caution: May cause drowning![citation needed]
Other systematic names for water include hydroxic acid or hydroxylic acid. Likewise, the systematic alkali name of water is hydrogen hydroxide—both acid and alkali names exist for water because it is able to react both as an acid or an alkali, depending on the strength of the acid or alkali it is reacted with (amphoteric). None of these names are used widely outside of DHMO sites.
See also
References
1. Braun, Charles L. (1993). "Why is water blue?" (HTML). J. Chem. Educ. 70 (8): 612. Unknown parameter |coauthors= ignored (help)
2. Lide, D. R. (Ed.) (1990). CRC Handbook of Chemistry and Physics (70th Edn.). Boca Raton (FL):CRC Press.
3. P. G. Debenedetti, P. G., and Stanley, H. E.; "Supercooled and Glassy Water", Physics Today 56 (6), p. 40–46 (2003).
4. The pressure due to water vapor in the air is called the partial pressure(Dalton's law) and it is directly proportional to concentration of water molecules in air (Boyle's law).
5. Adiabatic cooling resulting from the ideal gas law.
6. Brown, Theodore L., H. Eugene LeMay, Jr., and Bruce E. Burston. Chemistry: The Central Science. 10th ed. Upper Saddle River, NJ: Pearson Education, Inc., 2006.
7. Fine, R.A. and Millero, F.J. (1973). "Compressibility of water as a function of temperature and pressure". Journal of Chemical Physics. 59 (10): 5529. doi:10.1063/1.1679903.
8. 8.0 8.1 R. Nave. "Bulk Elastic Properties". HyperPhysics. Georgia State University. Retrieved 2007-10-26.
9. 9.0 9.1 Template:Cite paper
10. Template:Cite paper
11. William Cudmore McCullagh Lewis and James Rice (1922). A System of Physical Chemistry. Longmans, Green and co.
12. Choi, Eun-Mi; Yoon, Young-Hwan; Lee, Sangyoub; Kang, Heon. "Freezing Transition of Interfacial Water at Room Temperature under Electric Fields". Physical Review Letters. 95 (8): 085701. doi:10.1103/PhysRevLett.95.085701.
13. Connolly PJ, Saunders CPR, Gallagher MW, Bower KN, Flynn MJ, Choularton TW, Whiteway J, Lawson RP (2005). "Aircraft observations of the influence of electric fields on the aggregation of ice crystals". Quarterly Journal of the Royal Meteorological Society, Part B. 131 (608): 1695–1712. Unknown parameter |month= ignored (help)
14. Physical Forces Organizing Biomolecules (PDF)
15. Phil Schewe, James Riordon, and Ben Stein (31 Jul 03). "A Water Molecule's Chemical Formula is Really Not H2O". Physics News Update. Check date values in: |date= (help)
16. C. A. Chatzidimitriou-Dreismann, T. Abdul Redah, R. M. F. Streffer and J. Mayers (1997). "Anomalous Deep Inelastic Neutron Scattering from Liquid H2O-D2O: Evidence of Nuclear Quantum Entanglement". Physical Review Letters. 79 (15): 2839. doi:10.1103/PhysRevLett.79.2839.
17. C. A. Chatzidimitriou-Dreismann, M. Vos, C. Kleiner and T. Abdul-Redah (2003). "Comparison of Electron and Neutron Compton Scattering from Entangled Protons in a Solid Polymer". Physical Review Letters. 91 (5): 057403–4. doi:10.1103/PhysRevLett.91.057403.
18. http://home.comcast.net/~igpl/Temperature.html
19. Leigh, G. J. et al. 1998. Principles of chemical nomenclature: a guide to IUPAC recommendations, p. 99. Blackwell Science Ltd, UK. ISBN 0-86542-685-6
External links
Template:WH Template:WS Template:Jb1 af:water (molekule) de:Wassermolekül la:Aqua (moleculum) scn:Acqua (elimentu) sr:Вода (молекул) fi:vesi th:น้ำ (โมเลกุล)
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RedisTemplate序列化工具GenericJackson2JsonRedisSerializer
Redis作为高速缓存数据库，目前应用非常广泛。RedisTemplate是Spring提供用于操作redis数据库的一个类。
将数据存放到Redis中，以及数据读取。这里必然涉及到数据的系列化和反系列化。RedisTemplate默认的系列化类是JdkSerializationRedisSerializer，用JdkSerializationRedisSerializer序列化的话，被序列化的对象必须实现Serializable接口。在存储内容时，除了属性的内容外还存了其它内容在里面，总长度长，且不容易阅读。
我们要求是存储的数据可以方便查看，也方便反系列化，方便读取数据。
JacksonJsonRedisSerializer和GenericJackson2JsonRedisSerializer，两者都能系列化成json，但是后者会在json中加入@class属性，类的全路径包名，方便反系列化。前者如果存放了List则在反系列化的时候如果没指定TypeReference则会报错java.util.LinkedHashMap cannot be cast to 。
在项目中我们可以灵活设置RedisTemplate的系列化器。
这里写图片描述
我们可以看到RedisTemplate里面定义了key,value，hashKey,haskValue等键，值的系列化器，我们可以自己方便的修改。如果没有设置则会有默认的。
JdkSerializationRedisSerializer。
实例：设置RedisTemplate系列化。GenericJackson2JsonRedisSerializer系列化和反系列化使用的是ObjectMapper
package com.xfl.boot.common.config;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
/**
* Created by XFL
* time on 2017/6/12 23:24
* description:
*/
@Configuration
public class RedisConfig {
private static Logger logger = LoggerFactory.getLogger(RedisConfig.class);
@Bean(name = "springSessionDefaultRedisSerializer")
public GenericJackson2JsonRedisSerializer getGenericJackson2JsonRedisSerializer() {
return new GenericJackson2JsonRedisSerializer();
}
@Bean
public RedisTemplate<String, Object> getRedisTemplate(
JedisConnectionFactory connectionFactory) {
RedisTemplate<String, Object> redisTemplate = new RedisTemplate<String, Object>();
redisTemplate.setConnectionFactory(connectionFactory);
redisTemplate.setDefaultSerializer(new GenericJackson2JsonRedisSerializer());
StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
redisTemplate.setKeySerializer(stringRedisSerializer);
redisTemplate.setHashKeySerializer(stringRedisSerializer);
return redisTemplate;
}
}
//数据取出示例：
RespCallbackDto respCallbackDto = (RespCallbackDto) redisTemplate.opsForHash().get(key, prvId);
这里写图片描述
可以看到保存到redis数据库中的数据是json，并且每个节点都有@class属性，这些属性在凡系列化时会使用到。
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个人分类： redis/spring-data-redis
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| 0.597108 |
高级检索
汪克林, 曹则贤. 量子系统哈密顿量的必要条件[J]. 物理, 2022, 51(9): 645-648. DOI: 10.7693/wl20220906
引用本文: 汪克林, 曹则贤. 量子系统哈密顿量的必要条件[J]. 物理, 2022, 51(9): 645-648. DOI: 10.7693/wl20220906
WANG Ke-Lin, CAO Ze-Xian. Necessary condition for a Hamiltonian to be proper in quantum mechanics[J]. PHYSICS, 2022, 51(9): 645-648. DOI: 10.7693/wl20220906
Citation: WANG Ke-Lin, CAO Ze-Xian. Necessary condition for a Hamiltonian to be proper in quantum mechanics[J]. PHYSICS, 2022, 51(9): 645-648. DOI: 10.7693/wl20220906
量子系统哈密顿量的必要条件
Necessary condition for a Hamiltonian to be proper in quantum mechanics
• 摘要: 在此前的量子理论中，哈密顿量被要求是厄米算符，这既保证了其本征值谱为实又保证了动力学演化过程几率守恒。近年来，一些非厄米哈密顿量被发现同样满足这两条要求。然而，这两条要求都是哈密顿量可描述量子系统动力学的充分条件而非必要条件。文章中我们从量子化条件和动力学演化方程出发，考察一般形式的哈密顿量，表述为产生算符和湮灭算符之正规积的形式，欲为恰当的哈密顿量所应满足的必要条件。对于形如\hatH=\hatp^2+\mathrmi \hatx^3和\hatH=\hatp^2-\hatx^4这样的近年来得到广泛关注的非厄米哈密顿量，容易验证它们满足必要性条件。必要性条件可以用来及时排除那些不恰当的非厄米哈密顿量形式。
Abstract: In quantum mechanics, the Hamiltonians are required to be hermitian, since hermiticity guarantees that the energy spectrum is real and the time evolution is unitary. However, some non-hermitian Hamiltonians are also found meeting these requirements. The hermiticity is essentially a sufficient condition. In the current article, we formulate the necessary condition for a Hamiltonian to be proper in quantum mechanics, regarding the quantization condition it follows and the role it plays in the governing equation of dynamic evolution. It can be confirmed that the Hamiltonians adopted in quantum mechanics, even the non-hermitian ones such as\hatH=\hatp^2+\mathrmi \hatx^3 and \hatH=\hatp^2-\hatx^4, meet such a necessary condition. The necessary condition provides the first criterium for the candidate Hamiltonians to be introduced.
/
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Helpers
ServerUrlHelper
Mezzio\Helper\ServerUrlHelper provides the ability to generate a full URI by passing only the path to the helper; it will then use that path with the current Psr\Http\Message\UriInterface instance provided to it in order to generate a fully qualified URI.
Usage
When you have an instance, use either its generate() method, or call the instance as an invokable:
// Using the generate() method:
$url = $helper->generate('/foo');
// is equivalent to invocation:
$url = $helper('/foo');
The helper is particularly useful when used in conjunction with the UrlHelper, as you can then create fully qualified URIs for use with headers, API hypermedia links, etc.:
$url = $serverUrl($url('resource', ['id' => 'sha1']));
The signature for the ServerUrlHelper generate() and __invoke() methods is:
function ($path = null) : string
Where:
• $path, when provided, can be a string path to use to generate a URI.
Creating an instance
In order to use the helper, you will need to inject it with the current UriInterface from the request instance. To automate this, we provide Mezzio\Helper\ServerUrlMiddleware, which composes a ServerUrl instance, and, when invoked, injects it with the URI instance.
As such, you will need to:
• Register the ServerUrlHelper as a service in your container.
• Register the ServerUrlMiddleware as a service in your container.
• Register the ServerUrlMiddleware as pipeline middleware, anytime before the routing middleware.
The following examples demonstrate registering the services.
use Mezzio\Helper\ServerUrlHelper;
use Mezzio\Helper\ServerUrlMiddleware;
use Mezzio\Helper\ServerUrlMiddlewareFactory;
// laminas-servicemanager:
$services->setInvokableClass(ServerUrlHelper::class, ServerUrlHelper::class);
$services->setFactory(ServerUrlMiddleware::class, ServerUrlMiddlewareFactory::class);
// Pimple:
$pimple[ServerUrlHelper::class] = function ($container) {
return new ServerUrlHelper();
};
$pimple[ServerUrlMiddleware::class] = function ($container) {
$factory = new ServerUrlMiddlewareFactory();
return $factory($container);
};
// Aura.Di:
$container->set(ServerUrlHelper::class, $container->lazyNew(ServerUrlHelper::class));
$container->set(ServerUrlMiddlewareFactory::class, $container->lazyNew(ServerUrlMiddlewareFactory::class));
$container->set(
ServerUrlMiddleware::class,
$container->lazyGetCall(ServerUrlMiddlewareFactory::class, '__invoke', $container)
);
To register the ServerUrlMiddleware as pipeline middleware anytime before the routing middleware:
use Mezzio\Helper\ServerUrlMiddleware;
// Programmatically:
$app->pipe(ServerUrlMiddleware::class);
$app->pipeRoutingMiddleware();
$app->pipeDispatchMiddleware();
// Or use configuration:
// [
// 'middleware_pipeline' => [
// ['middleware' => ServerUrlMiddleware::class, 'priority' => PHP_INT_MAX],
// /* ... */
// ],
// ]
The following dependency configuration will work for all three when using the Mezzio skeleton:
return [
'dependencies' => [
'invokables' => [
ServerUrlHelper::class => ServerUrlHelper::class,
],
'factories' => [
ServerUrlMiddleware::class => ServerUrlMiddlewareFactory::class,
],
],
'middleware_pipeline' => [
['middleware' => ServerUrlMiddleware::class, 'priority' => PHP_INT_MAX],
/* ... */
],
];
Skeleton configures helpers
If you started your project using the Mezzio skeleton package, the ServerUrlHelper and ServerUrlMiddleware factories are already registered for you, as is the ServerUrlMiddleware pipeline middleware.
Using the helper in middleware
Compose the helper in your middleware (or elsewhere), and then use it to generate URI paths:
use Interop\Http\ServerMiddleware\DelegateInterface;
use Interop\Http\ServerMiddleware\MiddlewareInterface;
use Psr\Http\Message\ServerRequestInterface;
use Mezzio\Helper\ServerUrlHelper;
class FooMiddleware implements MiddlewareInterface
{
private $helper;
public function __construct(ServerUrlHelper $helper)
{
$this->helper = $helper;
}
public function process(ServerRequestInterface $request, DelegateInterface $delegate)
{
$response = $delegate->process($request);
return $response->withHeader(
'Link',
$this->helper->generate() . '; rel="self"'
);
}
}
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Statalist
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: RE: re: a question related to -foreach-
From "Nick Cox" <[email protected]>
To <[email protected]>
Subject st: RE: re: a question related to -foreach-
Date Tue, 21 Oct 2008 18:32:10 +0100
Notwithstanding this good advice, it may be of interest to see an answer
to the original question.
First, as does Kit, I assume that the number of observations is at least
36. This can always be achieved by -set obs- if it is not correct.
gen mean = .
local i = 1
qui foreach x of var b1-b36 {
su `x', meanonly
replace mean = r(mean) in `i'
local ++i
}
OR
gen mean = .
qui forval i = 1/36 {
su b`i', meanonly
replace mean = r(mean) in `i'
}
You will want to keep track of names too.
For example,
gen mean = .
gen varname = ""
local i = 1
qui foreach x of var b1-b36 {
su `x', meanonly
replace mean = r(mean) in `i'
replace varname = "`x'" in `i'
local ++i
}
Nick
[email protected]
Christopher Baum
Carlo asks
. foreach x of varlist b1-b36 {
2. summarize `x'
3. }
I would like to generate a newvar in which the r(mean) for each one
of the 36 variables included in varlist are stored. How can I do this
in Stata 9.2/SE?
No need to use a foreach loop.
tabstat b1-b36, save
mat mu = r(StatTotal)'
mat li mu
If for some reason you want these in a variable, use -svmat-:
svmat mu
which creates variable mu1, obs. 1-36.
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
© Copyright 1996–2014 StataCorp LP | Terms of use | Privacy | Contact us | What's new | Site index
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| 0.891322 |
food health weight loss wellness
The Goodness of Mushrooms
The Goodness of Mushrooms
Adding more mushrooms to your diet is a delicious way to improve your nutrition. While many classify mushrooms in the vegetable category, they are technically fungi, though they’re packed with vitamins, minerals, and health-promoting compounds, which makes them a smart addition to your meals. They can even make a good substitute for meat in most dishes, since they can have a denser, meatier texture and flavor.
So what makes many mushrooms so magical? First, they are a big boost to the immune system. They contain selenium, which helps your body produce T-cells, which are known as the killers of invading pathogens. The cell walls of mushrooms contain a compound called beta-glucan, which are fibers that stimulate the immune system to specifically hunt down cancer cells, and prevent the growth of tumors.
Since mushrooms are so high in antioxidants, they can help the repair of many tissues in your body. Not only that, but they tend to help the body regulate blood glucose and insulin levels. For anyone with blood sugar control issues, this is a big deal. Specifically, people with diabetes or prediabetic conditions can see benefits in this regard.
Mushrooms are a high fiber food. This means they can fill you up at meal time, and you’ll stay satisfied for many hours afterwards. The fiber in mushrooms can help to feed the good probiotic bacteria in your gut, so you can have improved digestion. You can also experience weight loss from adding more mushrooms to your diet.
Your heart will thank you, too. Mushrooms contain potassium and vitamin C, both of which we all could use more of. The potassium is especially important for the heart’s muscle tissue. Sodium and potassium work together and need to be balanced in our diet. Most of us get plenty of sodium, but not enough potassium, so mushrooms can help rebalance this equation. Plus, you’ll be helping to regulate your blood pressure and cholesterol levels.
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39 + = 44
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__label__pos
| 0.878211 |
Journal of Tropical Ecology
Effects of fire, food availability and vegetation on the distribution of the rodent Bolomys lasiurus in an Amazonian savanna
Viviane Maria Guedes Layme a1, Albertina Pimentel Lima a1c1 and William Ernest Magnusson a1
a1 Coordenação de Pesquisas em Ecologia, Instituto Nacional de Pesquisas da Amazônia, CP 478, 69011-970 Manaus-AM, Brazil
Article author query
layme v [PubMed][Google Scholar]
lima a [PubMed][Google Scholar]
magnusson w [PubMed][Google Scholar]
Abstract
We investigated the relative influences of vegetation cover, invertebrate biomass as an index of food availability and the short-term effects of fires on the spatial variation in densities of the rodent Bolomys lasiurus in an Amazonian savanna. Densities were evaluated in 31 plots of 4 ha distributed over an area of approximately 10×10 km. The cover of the tall grass (Trachypogon plumosus), short grass (Paspalum carinatum), shrubs and the extent of fire did not explain the variance in densities of Bolomys lasiurus. Food availability alone explained about 53% of the variance in B. lasiurus densities, and there was no significant relationship between insect abundance and vegetation structure. Fires had little short-term impact on the density of Bolomys lasiurus in the area we studied. As the species appears to respond principally to food availability, habitat suitability models based on easily recorded vegetation-structure variables, or the frequency of disturbance by fire, may not be effective in predicting the distribution of the species within savannas.
(Accepted April 12 2002)
Key Words: Amazon; grassland; habitat; population; rat.
Correspondence:
c1 Corresponding author. Email: [email protected]
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| 0.664058 |
To Terminate or Attenuate?
To Terminate or Attenuate?
Terminations and attenuators can handle high power levels at microwave frequencies, and advanced materials are enabling them to do so in smaller packages.
Download this article in .PDF format
This file type includes high resolution graphics and schematics when applicable.
Attenuators and terminations are commonly-used components in high-frequency systems, used to adjust or absorb power, respectively. In many ways, the two types of components are similar, since they are both designed to stop RF/microwave power. Attenuators decrease some portion of the power, in fixed or variable amounts, while terminations stop power applied to them altogether.
Both types of components are available in various forms, from miniature chips to higher-power coaxial components and the highest-power waveguide assemblies. Both types of components play important roles in high-frequency circuits and systems, especially when high-power signals must be managed.
Fig. 1
Aettnuators and terminations must both handle high power levels, with some key differences.
Attenuators and, in particular, high-power terminations are usually specified with size, weight, power-handling capability, and frequency range as essential parameters for comparison. Power-handling capability is generally a function of size, with the highest-power components occupying the greatest amount of volume in a design.
A termination is a one-port component meant to absorb all the power applied to it, while an attenuator is a two-port component that reduces the level of the power passing through it by a fixed or variable amount. Attenuators can reduce signal power by a fixed amount or can provide an adjustable range of attenuation. For the most part, adjustments are continuously variable or switched in discrete steps.
Terminations are typically connected at an unused port in a system, such as an unused port of a power divider that is splitting off signal power to other parts of the system. In addition, terminations are used when a passive component (such as a filter or a coupler) is being matched to 50 Ω for measurement purposes, as when testing for return loss or power-handling capability. Terminations used for establishing reference impedances at high power levels are usually referred to as dummy loads.
Matching an attenuator or termination to an application is a matter of understanding the main operating parameters and making the best choice of component for a particular set of requirements. Attenuators are available with fixed attenuation values for a particular frequency range or with a range of attenuation settings that can be set in steps or under continuously variable control.
Whether fixed or variable, attenuators can be compared in terms of bandwidth, attenuation flatness across the frequency range, insertion loss, return loss or VSWR, power-handling capability, operating temperature range, size, and weight. For more on the fundamental operating parameters of RF/microwave attenuators, see “Know When To Add Attenuation.”
Terminating Power
As with attenuators, terminations are available in many form factors. These include miniature chips, coaxial packages, and high-power waveguide components, generally with power ratings to match their sizes. Terminations are characterized by fewer parameters than attenuators, since they do not exhibit amplitude responses as a function of frequency. Rather, the frequency range of a termination is the span of frequencies over which it can maintain an impedance match with a system’s characteristic impedance—usually 50 Ω, but sometimes 75 Ω for broadcast applications or other impedances for specialized uses.
An important function of an RF/microwave termination, especially for high-power models, is its capability to dissipate heat. Any type of power-absorbing component, such as a termination, can dissipate heat by means of conduction, convection, or radiation. Conduction takes place by means of physical contact of different materials, such as a flange-mounted termination to a heat sink.
Conduction occurs when heat is dissipated as it moves from areas of higher energy to areas of lower energy. Convection is a dissipation of heat from a source by means of a flowing liquid (such as water) or a flowing gas (including air, as in fan-cooled terminations). Thermal radiation occurs when a source emits EM waves that carry the heat energy—e.g., infrared (IR) radiation, as used in space heaters.
Any resistive element, including attenuators and terminations, will generate heat that must be dissipated to minimize temperature-related stress and ensure the long-term reliability of a component, circuit, or system. For that reason, terminations are usually fabricated from or packaged in a material with high value of emissivity or heat radiation efficiency.
An ideal thermal radiator would have an emissivity value of 1. While no materials exhibit that thermal radiating efficiency, aluminum comes close, with an emissivity of 0.9. For that reason, aluminum is often used to construct extremely high-power terminations, dummy loads, and attenuators.
Terminations are somewhat simpler to specify than RF/microwave attenuators, since the primary goals of any termination are to establish a good match with the system characteristic impedance and to absorb and dissipate a certain amount of power. As for attenuators, the number of suppliers for high-frequency terminations is large, with package styles ranging from tiny chip terminations to much larger waveguide terminations. As noted, heat must be dissipated, so the power-handling capabilities of these different terminations are related to physical size and connections to surrounding circuitry.
For example, American Technical Ceramics, which supplies both attenuators and terminations, supplies circuit-board-mountable components but in different packages and with different power ratings. The firm’s leaded and surface-mount-technology terminations are well suited for densely packed PCBs. However, these tiny components cannot match the power-handling and thermal-management capabilities of slightly larger flange-mount terminations and their larger cross-sectional mounting connections for effective thermal dissipation.
Res-Net Microwave builds its chip terminations and resistors on thermally dissipative beryllium oxide (BeO) substrate material, allowing for relatively large power-handling capabilities in small component sizes. The firm supplies terminations in most major package styles (see figure). These include conduction- and convection-cooled coaxial terminations with SMA connectors for use at power levels to 250 W from DC to 4 GHz, and the same power rating through 3 GHz with Type-N and TNC coaxial connectors.
The power-handling capabilities drop with increasing frequency, to about 50 W for SMA terminations operating to 18 GHz. The firm offers chip terminations based on its BeO substrates rated to 15 W at microwave frequencies.
Another material building block for high-power terminations is aluminum oxide, A2O3, also known as alumina, long a favorite substrate for high-power passive RF/microwave components. As an example, the chip resistors fabricated by US Microwaves on alumina substrates can also be used as chip terminations at power levels beyond 100 W through microwave frequencies.
The material supports a wide operating temperature range, from -65 to +200°C. Similarly, aluminum nitride material is effective for thermal dissipation, and is often used in packaging for high-power attenuators and terminations.
In spite of the thermal advantages of composite materials, higher power levels will require larger terminations to safely dissipate heat from a high-frequency design. Material advances have made possible some impressive power ratings for chip and SMT resistors, terminations, and attenuators. Nevertheless, higher-power applications, such as communications transmitters and radar systems, will still require the largest terminations and attenuators, usually with waveguide flanges for consistent dissipation of power levels that often exceed 1 kW CW.
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__label__pos
| 0.940314 |
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Connecting to a SQL Server CE Database
SQL Server 2000
Before you can manipulate information in a database, you must open a connection to a valid data source. The Connection object is used to represent a connection to a data source. To open a connection to a data source, create a variable that represents the connection, and then create a Microsoft® ActiveX® Data Object for Windows® CE (ADOCE) Connection object by using the Set statement and CreateObject function. The following example shows how to do this:
Dim cn As ADOCE.Connection
Set cn = CreateObject("ADOCE.Connection.3.1")
Note When you use the CreateObject function to create a reference to the ADOCE 3.1 control, you must include the version number. If the version number is omitted from the string, an earlier version of the control is used. If no earlier version of the control exists on the device, an error is returned. Microsoft SQL Server™ 2000 Windows CE Edition (SQL Server CE) can be accessed only through ADOCE 3.1 or later.
After a Connection object is created, you can use the properties and methods of the Connection object to open, close, and manipulate a connection. The following example shows how to open a connection to a database on the device by using the Open method:
cn.ConnectionString = "Provider=Microsoft.SQLSERVER.OLEDB.CE.2.0; data source=\Northwind.sdf"
cn.Open
Caution You must specify the SQL Server CE provider string when you open a SQL Server CE database. If you do not specify a provider string in the Open method, Open defaults to using the proprietary Windows CE data source and creates a new Windows CE data source file named Test.sdf. This is the equivalent of specifying CEDB for the Provider property in the connection string.
In the previous sample, the connection string property is set before the Open method is executed. The Open method is used without any parameters. A connection string can also be used as a parameter of the Open method. When connecting to a SQL Server CE database, you must specify both the provider and data source properties in the connection string. The data source property must be set with the full path and database name.
Disconnecting from a Database
After you make modifications and save them to the database, close the connection to the data source. The following example shows how to use the Close method to close a connection:
cn.Close
Set cn = Nothing
Note You can have only one open connection to a SQL Server CE database at a time, and this connection must be closed before starting replication or remote data access (RDA).
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© 2015 Microsoft
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__label__pos
| 0.921354 |
Lymphatic Circulation
Lymph travels through a network of small and large channels that are in some ways similar to the blood vessels. However, the system is not a complete circuit. It is a oneway system that begins in the tissues and ends when the lymph joins the blood (see Fig. 12-1).
Lymphatic Capillaries
The walls of the lymphatic capillaries resemble those of the blood capillaries in that they are made of one layer of flattened (squamous) epithelial cells. This thin layer, also called endothelium, allows for easy passage of soluble materials and water (Fig. 12-3). The gaps between the endothelial cells in the lymphatic capillaries are larger than those of the blood capillaries. The lymphatic capillaries are thus more permeable, allowing for easier entrance of relatively large protein particles. The proteins do not move back out of the vessels because the endothelial cells overlap slightly, forming one-way valves to block their return. Unlike the blood capillaries, the lymphatic capillaries arise blindly; that is, they are closed at one end and do not form a bridge between two larger vessels. Instead, one end simply lies within a lake of tissue fluid, and the other communicates with a larger lymphatic vessel that transports the lymph toward the heart (see Figs. 12-1 and 12-2).
Some specialized lymphatic capillaries located in the lining of the small intestine absorb digested fats. Fats taken into these lacteals are transported in the lymphatic vessels until the lymph is added to the blood.
The lymphatic system in relation to the cardiovascular system
Pathway of lymphatic drainage in the tissues
Figure 12-2 Pathway of lymphatic drainage in the tissues. Lymphatic capillaries are more permeable than blood capillaries and can pick up fluid and proteins left in the tissues as blood leaves the capillary bed to travel back toward the heart.
Structure of a lymphatic capillary
Figure 12-3 Structure of a lymphatic capillary. Fluid and proteins can enter the capillary with ease through gaps between the endothelial cells. Overlapping cells act as valves to prevent the material from leaving.
Lymphatic Vessels
The lymphatic vessels are thin walled and delicate and have a beaded appearance because of indentations where valves are located (see Fig. 12-1). These valves prevent back flow in the same way as do those found in some veins. Lymphatic vessels (Fig. 12-4) include superficial and deep sets. The surface lymphatics are immediately below the skin, often lying near the superficial veins. The deep vessels are usually larger and accompany the deep veins. Lymphatic vessels are named according to location. For example, those in the breast are called mammary lymphatic vessels, those in the thigh are called femoral lymphatic vessels, and those in the leg are called tibial lymphatic vessels. At certain points, the vessels drain through lymph nodes, small masses of lymphatic tissue that filter the lymph. The nodes are in groups that serve a particular region. For example, nearly all the lymph from the upper extremity and the breast passes through the axillary lymph nodes, whereas lymph from the lower extremity passes through the inguinal nodes. Lymphatic vessels carrying lymph away from the regional nodes eventually drain into one of two terminal vessels, the right lymphatic duct or the thoracic duct, both of which empty into the bloodstream.
Figure 12-1 The lymphatic system in relation to the cardiovascular system. Lymphatic vessels pick up fluid in the tissues and return it to the blood in vessels near the heart.
Figure 12-4 Vessels and nodes of the lymphatic system. (A) Lymph nodes and vessels of the head. (B) Drainage of right lymphatic duct and thoracic duct into subclavian veins.
The Right Lymphatic Duct The right lymphatic duct is a short vessel, approximately 1.25 cm (1/2 inch) long, that receives only the lymph that comes from the superior right quadrant of the body: the right side of the head, neck, and thorax, as well as the right upper extremity. It empties into the right subclavian vein near the heart (see Fig. 12-4 B). Its opening into this vein is guarded by two pocket-like semilunar valves to prevent blood from entering the duct. The rest of the body is drained by the thoracic duct.
The Thoracic Duct The thoracic duct, or left lymphatic
duct, is the larger of the two terminal vessels, measuring approximately 40 cm (16 inches) in length. As shown in
Figure 12-4, the thoracic duct receives lymph from all parts of the body except those superior to the diaphragm on the right side. This duct begins in the posterior part of the abdominal cavity, inferior to the attachment of the diaphragm. The first part of the duct is enlarged to form a cistern, or temporary storage pouch, called the cisterna chyli. Chyle is the milky fluid that drains from the intestinal lacteals, and is formed by the combination of fat globules and lymph. Chyle passes through the intestinal lymphatic vessels and the lymph nodes of the mesentery (membrane around the intestines), finally entering the cisterna chyli. In addition to chyle, all the lymph from below the diaphragm empties into the cisterna chyli, passing through the various clusters of lymph nodes. The thoracic duct then carries this lymph into the bloodstream. The thoracic duct extends upward through the diaphragm and along the posterior wall of the thorax into the base of the neck on the left side.
Here, it receives the left jugular lymphatic vessels from the head and neck, the left subclavian vessels from the left upper extremity, and other lymphatic vessels from the thorax and its parts. In addition to the valves along the duct, there are two valves at its opening into the left subclavian vein to prevent the passage of blood into the duct.
Movement of Lymph
The segments of lymphatic vessels located between the valves contract rhythmically, propelling the lymph along. The contraction rate is related to the volume of fluid in the vessel the more fluid, the more rapid the contractions. Lymph is also moved by the same mechanisms that promote venous return of blood to the heart. As skeletal muscles contract during movement, they compress the lymphatic vessels and drive lymph forward. Changes in pressures within the abdominal and thoracic cavities caused by breathing aid the movement of lymph during passage through these body cavities.
Contacts: [email protected] www.encyclopedia.lubopitko-bg.com Corporation. All rights reserved.
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How to plot a graph in Python
Python provides one of a most popular plotting library called Matplotlib. It is open-source, cross-platform for making 2D plots for from data in array. It is generally used for data visualization and represent through the various graphs.
Matplotlib is originally conceived by the John D. Hunter in 2003. The recent version of matplotlib is 2.2.0 released in January 2018.
Before start working with the matplotlib library, we need to install in our Python environment.
Installation of Matplotlib
Type the following command in your terminal and press enter.
The above command will install matplotlib library and its dependency package on Window operating system.
Basic Concept of Matplotlib
A graph contains the following parts. Let's understand these parts.
How to plot a graph in Python
Figure: It is a whole figure which may hold one or more axes (plots). We can think of a Figure as a canvas that holds plots.
Axes: A Figure can contain several Axes. It consists of two or three (in the case of 3D) Axis objects. Each Axes is comprised of a title, an x-label, and a y-label.
Axis: Axises are the number of line like objects and responsible for generating the graph limits.
Artist: An artist is the all which we see on the graph like Text objects, Line2D objects, and collection objects. Most Artists are tied to Axes.
Introduction to pyplot
The matplotlib provides the pyplot package which is used to plot the graph of given data. The matplotlib.pyplot is a set of command style functions that make matplotlib work like MATLAB. The pyplot package contains many functions which used to create a figure, create a plotting area in a figure, decorates the plot with labels, plot some lines in a plotting area, etc.
We can plot a graph with pyplot quickly. Let's have a look at the following example.
Basic Example of plotting Graph
Here is the basic example of generating a simple graph; the program is following:
Output:
How to plot a graph in Python
Ploting Different Type of Graphs
We can plot the various graph using the pyplot module. Let's understand the following examples.
1. Line Graph
The line chart is used to display the information as a series of the line. It is easy to plot. Consider the following example.
Example -
Output:
The line can be modified using the various functions. It makes the graph more attractive. Below is the example.
Example -
2. Bar Graph
Bar graph is one of the most common graphs and it is used to represent the data associated with the categorical variables. The bar() function accepts three arguments - categorical variables, values, and color.
Example -
3. Pie Chart
A chart is a circular graph which is divided into the sub-part or segment. It is used to represent the percentage or proportional data where each slice of pie represents a particular category. Let's understand the below example.
Example -
Output:
How to plot a graph in Python
4. Histogram
The histogram and bar graph is quite similar but there is a minor difference them. A histogram is used to represent the distribution, and bar chart is used to compare the different entities. A histogram is generally used to plot the frequency of a number of values compared to a set of values ranges.
In the following example, we have taken the data of the different score percentages of the student and plot the histogram with respect to number of student. Let's understand the following example.
Example -
Output:
How to plot a graph in Python
Let's understand another example.
Example - 2:
Output:
How to plot a graph in Python
5. Scatter Plot
The scatter plot is used to compare the variable with respect to the other variables. It is defined as how one variable affected the other variable. The data is represented as a collection of points. Let's understand the following example.
Example -
Output:
How to plot a graph in Python
Example - 2:
Output:
How to plot a graph in Python
In this tutorial, we have discussed all basic types of graph which used in data visualization. To learn more about graph, visit our matplotlib tutorial.
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JamesT JamesT - 1 year ago 65
Python Question
Dictionary of lists from tab delimited file
I'm attempting to load a tab delimited text file into a python program. It has the following format,
AAAAAA 1234 5678 90AB QQQQ JKL1
BBBBBB QWER TYUI ASDF QQQQ
CCCCCC ZXCV 1234 PPPP
...
ZZZZZZ 1111
In short, variable numbers of columns for each row, but always at least two and each column within a row is unique. The first column I would like to use as a key, and load the rest into a list with the key pointing to it. I tried looking into the csv module already as was suggested in other threads, but I've not quite found a way to make it work for me. So yeah, apologies if this should be more obvious, very much a newbie question.
Answer Source
simple str.split should work just fine for splitting the columns. Using that, you just need to read each row and split it into columns taking the first element as the key and the rest as the value:
with open(file) as fin:
rows = ( line.split('\t') for line in fin )
d = { row[0]:row[1:] for row in rows }
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Teacher resources and professional development across the curriculum
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The Habitable Planet - A Systems Approach To Environmental ScienceHabitable Planet home page
Interview with Howard Hu
Interviewer: How did you get interested in science?
HOWARD: Well, my parents were Chinese immigrants. My father was an engineer and he pushed me towards medicine but I was much more interested in broader things about society. I grew up in the 1970s, and environmental health and occupational health came to me early on through a personal experience when I was exposed to asbestos while working in a shipyard. I knew from that experience that I was at increased risk for lung cancer and a disease that would shrink my lungs. When I found out that asbestos was something that had been regulated for years but poorly enforced, allowing me to be exposed, I realized that I had stumbled upon a field that was at the intersection of health, politics, social economics. And it was very interesting to me.
Interviewer: How is your health now due to the asbestos exposure?
HOWARD: Oh, I’m not about to keel over. I’m okay. But, I do have to get checked out and have a chest X-ray every three to five years.
Interviewer: What is the fundamental research question that you and your team are working on at Tar Creek?
HOWARD: The fundamental research question we’re addressing at the Tar Creek Superfund Site is, “What are the health effects of mixtures of metals, in this case, the mixtures of lead, manganese, cadmium, and arsenic that exist in mining waste?”
Interviewer: Can you explain what a Superfund site is?
HOWARD: A Superfund site, in general, is one that has been designated a high priority area of contamination by the Environmental Protection Agency (EPA). They keep this list, called the National Priority List, which I believe has over two thousand sites. The sites are rated based on the number of contaminants, how toxic they are, and the potential for human exposure.
Interviewer: Tar Creek was one of the earliest listings, and one of the most extreme?
HOWARD: That’s correct. This was one of the first sites that was so designated on the National Priority List, because of its size and the immediate recognition that metals exposure was a hazard.
Interviewer: How did you get involved with the research at Tar Creek?
HOWARD: The story really goes back about twelve years or so. This is an area of the country where metals have been mined for many decades. And people have been living amidst these mountains of mining waste during that time without a good idea of how it was affecting their health. In the 1970s this was one of the areas that was designated as a Superfund site because of the recognition that the exposure to metals must be relevant. But no health studies had been done.
In the mid 1990s, a woman named Rebecca Jim, who’s the head of a community agency called Local Environmental Action Demanded (I love that acronym, LEAD), contacted me after reading about some of our research and asked me whether I could be interested in their exposures, and whether I could measure some of the teeth that she had collected from school aged children for lead. She had read some of our research which indicated that tooth lead levels provide a metric for understanding how much lead exposure a child had endured during the first few years of life. We measured those teeth. The levels were relatively high. And, that began a relationship in which she encouraged us to come to the Tar Creek Superfund Site and try to shed some light on what the health impacts of the mining waste were in this community.
Around 2001, we began to do some research with support from the Harvard Superfund Basic Research Program. And, then in 2004, we got a major grant from the National Institute of Environmental Health Sciences and the Environmental Protection Agency to make this the focal point of our human population work stemming from our Center for Children’s Environmental Health and Disease Prevention Research.
Interviewer: When I went to visit Tar Creek, there was mention of research being done on aquifers.
HOWARD: The research on the aquifers has mostly been conducted by the United States Geological Survey. We have used that research to provide a preliminary assessment of what the metals exposure might be in the residents. Our research is much more focused on the immediate environment of the residents living in the Tar Creek Superfund Site, trying to understand what their exposures might be from house dust, soil, air, drinking water, food, so that we have a better idea of how these metals may travel from these mining sites and from these aquifers to the actual people themselves.
Interviewer: What are the big questions at the base of your research, and how does it fit in with the bigger picture of general health and the work you’re doing here as well?
HOWARD: In terms of the big picture, environmental health as a science has become increasingly sophisticated over these years and now we have very good ideas based on basic research in the laboratory and human population studies of what individual toxicants can do to people, whether it’s asbestos, or benzene, or lead.
One of the big questions that we’re trying to get at, however, is how mixtures of toxicants, in this case metals, may affect human health. And, there is good evidence from basic research work that you cannot predict what the ultimate human health impacts might be from simply knowing what the individual toxicants can do. Mixtures can, in the most extreme cases, interact in ways that are unforeseen and give you toxic ramifications that are much greater than what could be predicted from the single exposures. On the other hand, in some mixtures, toxicants can cancel out the effects of each other. So this research, which is a combination of human population studies and basic science studies in the laboratory, is trying to attack this problem using a well-integrated systematic approach of studies to understand the health effects of mixtures.
Interviewer: How do you break down such a big question into research topics? What are you actually studying right now that contributes to answering the “big question”?
HOWARD: The big picture question that we’re looking at is, “What are the health effects of mixtures of metals?” This is a question that can be broken down into how these mixtures of metals move from these mining waste sites into the immediate vicinity of people with potential for exposure in drinking water, and food, and air. Then it can be broken down into how these things might interact inside the gut, or in the lungs, or in the brain, to eventually cause toxicity.
This particular set of studies is focusing on early life, probably because pregnancy and the first two years of life are generally recognized as being extremely vulnerable periods to toxicants, particularly neurologically – brain affecting – toxicants.
Interviewer: Can you explain the different projects involved in this study?
HOWARD: There are actually five major projects in our package of studies. Three of them are human population studies. I’ll describe those first. One of them is known as a birth cohort study. We’re actually recruiting women who are giving birth at a local hospital and measuring the levels of metals that appear in the umbilical cord blood, in mom’s hair, and in the infants as they develop. And then we follow those infants and try to understand how those metal exposures may impact neurodevelopment. The second human population study is looking at how these mothers are actually exposed to metals by looking at what’s in their air, what’s in their food, what’s in their drinking water, what’s in their house dust. The house dust also is important for the babies as they grow up, because hand to mouth behavior in babies is normal. And they are always exposed to house dust. The third human population study is looking at the general environment of where the Tar Creek residents live and looking at how the metals might travel from the chat piles - these large mountains of mining waste - into the drinking water, into the soil, and into the road where the waste that gets churned up by activities like cars driving through creates dust that people can breathe.
Interviewer: What are some of the previous findings that indicate the need to learn more about the Tar Creek area?
HOWARD: Some of the previous work that has led us to focus on the Tar Creek Superfund Site, including samples by the Environmental Protection Agency and the Geological Survey of the Federal Government, indicate high levels of metals throughout the entire Tar Creek Superfund area. There have also been some exposure studies involving biological samples, such as the Tribal Efforts Against Lead Study, conducted by researchers from the University of Oklahoma, that showed elevated levels of lead in children aged two and three years.
Interviewer: Can you tell me bit about the types of warning signs a community must experience in order to take the health hazards of mining seriously? Is it the health issues that catalyze action, or something else?
HOWARD: The issue of mining and a community’s health is very complex. We have focused on the issue of metals exposure and its impact on development. It’s a subtle issue. If metals actually lower your child’s I.Q. by five points or ten points, it’s not something you’re ever going to recognize. But it’s something obviously that will be hugely important for parents as well as the children. That’s subtle. And it doesn’t surprise me that residents in a toxic site where there might be severe implications may not have that as a front burner issue for them because it’s hard to see. On the other hand, mining also involves physical hazards, such as the collapse of ground under houses, under roads, because of unregistered mining sites and what are called cave-ins. Those are more obvious physical threats that bring these issues immediately to the forefront, to the public. They’re linked, of course, because these are all related to mining. One has to bring all issues to the forefront to a community, and they have to be done in a linked way so that the community can really understand in a holistic way how mining might be a threat to their health.
Interviewer: Can you describe some of the studies conducted in a lab that complement the studies of human populations?
HOWARD: This Center involves basic science studies performed in the laboratory that are integrated with our human population studies. One of these studies involves taking actual chat mining waste and exposing animals, in this case mice and rats, and trying to see how the metals interact with each other and how the animals absorb the effect - their absorption in the gut, or in the nose, or in the lungs. Among the early findings that we have uncovered in this research is that, in fact, respiratory exposure and nasal exposure may be an extremely relevant route of exposure for manganese, a metal that’s well known to be a neurotoxin. Part of that is related to the fact that olfaction, that is the sense of smell, involves a nerve that goes directly from the brain to the sinuses. And manganese can actually be absorbed right through the sinus into that nerve and transport it directly to the brain, without ever having to be absorbed into blood. This is one of the surprising findings that may explain some of the most relevant neurotoxin potential for a metal like manganese.
Another of our animal studies is looking at neurotoxicity in a more direct manner by injecting or exposing these animals to mixtures of metals and looking at neurobehavioral outcomes, such as the ability of these animals to remember, to sustain life through stresses, and their ability to do specific tasks involving coordination. All of these kinds of studies will go a long way to helping us understand how these mixtures of metals may affect neurodevelopment in children.
Interviewer: How long have you been doing animal studies and what are your findings so far?
HOWARD: For almost two years. One of the studies has told us that the sinus and nasal route of absorption might be extremely relevant. Another of the studies tells us that manganese may be more toxic than we thought and may interact with arsenic to increase its impact on child development.
Interviewer: Are the levels of human exposure to hazardous metals (or metal mixtures) going up, down, or staying the same?
HOWARD: It’s a very mixed, moving picture in which we only have small pieces of the puzzle. It’s too early to understand whether the overall trend for human exposure is going up, going down, or flat. We simply don’t have that data yet.
Interviewer: Will you or do you study what happens to the people who deal directly with the mining waste?
HOWARD: We’d like to be able to do that. Right now we’re focusing on the mother/infant pairs and their exposures. But it will also be important to see whether the workers who are using the mining waste, as you mentioned, and are shoveling it out of trucks, and who are there when it’s being pulverized into dust are significantly exposed. And we would like to know whether the secondary use, trucking it to other parts, of the country may eventually result in significant exposures. We simply don’t know.
Interviewer: How does weathering affect the risk of exposure?
HOWARD: One of the potentially helpful effects of weathering may be to develop crusts that will keep down the level of dust in respirable particles. Weathering may also produce the actual waste that’s in the immediate environment by getting it further down into soil, where it’s less available for human exposure.
Interviewer: Regarding Tar Creek, do you have any gut feeling about what the future holds?
HOWARD: I don’t anticipate that there are going to be major changes over decades. There will be subtle changes as the years go by. I think that some of the movement of the residents may address some of the questions of human exposure. But certainly not all of them, given the multiple sites that are impacted in this Superfund area as well as the use of this chat all over the state.
Interviewer: The WHO (World Health Organization) publishes acceptable exposure levels, but your studies have found that exposure levels below the WHO standard may still have neurological effects, among other things. Can you compare your findings with global findings, or will your studies affect WHO levels?
HOWARD: Well, again, our study is focused on the big picture issue of how mixtures may impact human health. This is not an issue that WHO has considered in setting its standards, or, for that matter, the United States Centers for Disease Control. So it could be considered as a cutting edge issue in environmental health. The exposures information that we have so far in the children being born is somewhat encouraging, showing that the exposures aren’t quite as high as they had been measured perhaps ten or fifteen years ago. We don’t know yet why that might be true, or whether it’s true for all children in this area. But we’re certainly hopeful that the residents, as they gain more knowledge of these exposures, their potential effects, and how to avoid them, may be actually reducing their own exposures through simple common sense measures, some of which we are already beginning to promote as measures people can take. And that’s maybe why we’re seeing a reduction over time.
Interviewer: Can you briefly mention how your project ties into the larger world?
HOWARD: The world implications of the subjects that we’re studying include the fact that metals are now recognized as being more diverse in their ability to affect our health than had been known before. For instance, manganese and arsenic, which are metals that, in the past we knew were toxic at high levels to adults, are now seen as potential threats to child development, something that has not been appreciated before. Arsenic is also something that is a risk for neurodevelopmental toxicity, not just cancer. And, that’s a new revelation for metals.
Mining is a process that occurs all over the world, in this country, in developed countries, and in a developing world, at an increasing pace as industrialization fuels the need for all these metals in mega quantities for manufacturing. That means that what we’re discovering will have implications for communities all over the world who are exposed to this metal mining waste.
Interviewer: What are some of the uses for the metals that were mined at the Tar Creek mining area?
HOWARD: The Tar Creek mining area was a source of metals for our nation’s industries and our armaments for many decades. A lot of the ammunition that was used in World War Two, in fact, had its origins in metal mines of Tar Creek.
Interviewer: Other than educating the public, as you said, are there any other things we can do to mitigate the hazards of the mine waste?
HOWARD: I am hopeful that our research will allow us to better target interventions for people, including those who are living in the worst areas of mining waste. Among the interventions may be nutritional interventions emphasizing various nutrients that may decrease absorption of toxic metals that may mitigate the ultimate toxic affects. Avoidance of some lifestyles, whether it’s food sources or behaviors that will increase exposure. And, if necessary, drug treatments that can reduce metal levels in the body or at key target organs to improve outcomes. Those are all possible interventions in an area where the exposures are extreme or inevitable. Public health measures or sociologic measures, like moving people, of course, are another drastic measure that have to considered, and are being considered at the Tar Creek Superfund Site.
Interviewer: So, can you concisely sum up and describe the health component of what you are studying at the Tar Creek Superfund Site?
HOWARD: The health component of what we’re focusing on at the Tar Creek Superfund Site is child development, specifically neurodevelopment. How well can these children think and perform as they get into school age? What is their I.Q.? What is their coordination? What is their ability to think abstractly? Those are all key skills that our children need, particularly since today’s world is a knowledge-based economy. They have to be able to think well. That is not the only health implication that has to be considered over time. Adults are also at risk. Our particular research group has other research projects which have shown that metals exposure may ultimately result in adults in hypertension, heart attacks, accelerated declines in thinking ability, Alzheimer’s, Parkinson’s Disease. And, finally, there’s the recognition that children’s exposures may actually manifest themselves as adult disease later in life. That’s called the fetal origins of adult disease hypothesis, a very important theory that may have currency in today’s world.
Interviewer: How old are the children you have been studying? I visited with the principal of the school and she claims that she sees the effects in her students, but has any study been done on those students?
HOWARD: Not yet. At this point, we’re following the mother/infant pairs who were initially enrolled in our study. And the oldest children are only around three years old or so. Our eventual goal is to try to follow them as they get into school and understand how their exposures may impact behaviors that every parent/teacher knows.
Interviewer: Can you comment on what the implications are of relocating a lot of the hazardous mining to places outside the US?
HOWARD: I think the issue of something like mining metals has become a global issue. It is an issue of economics, not just politics. In environmental health we call this the exportation of hazardous wastes, products, and industries. And mining is one of those industries that has moved offshore. Nowadays, a lot of the metals that we enjoy in our products, in our country, stem from mines that are in Indonesia, Malaysia, India, Africa, and we do have to think about how these communities that live around these mining sites are affected. Eventually, it all gets down to the globalization of the world’s economies and, our interdependence in not only commerce, but people. We will eventually be affected if the communities around mines in South Africa, or Malaysia, are poisoned by these wastes, not only through the court systems, but also through civil unrest, by other injunctions and protests, and people who understand that fundamentally the world is responsible for the health of people when our economies are this interdependent. That’s part of the implications of what we’re doing with mining waste research.
Interviewer: Are there other types of mines, different from the Tar Creek mines that cause health hazards?
HOWARD: Yes. The issue of mining and health extends far beyond the kinds of mines that we’re studying. Mines that are focused on gold actually use mercury, which has been imported as part of the purification process, and that has led to extreme contamination in some environments, like in Brazil. Mining for uranium, which is huge for nuclear fuel, involves uranium tailings that are a huge radiation threat to populations living around mines. So there are complicated issues that are specific for the substance that’s being mined and the eventual risks that the communities surrounding those mines are exposed to.
Interviewer: There’s still quite a bit of copper being mined in this state (OK). Is that process a bit cleaner than that of some other minerals that are being mined, or does that also have other kinds of hazards?
HOWARD: Copper mining also involves a number of different threats, including collateral exposures to arsenic and lead, and through the smelting process, the purification process, exposure to those metals affects communities surrounding the smelter.
Interviewer: Can you explain what the collateral damages are?
HOWARD: A big issue with mines is exposure not only to the metal that’s being mined, but collateral exposure and health affects from the other metals that derive from the ore that produces the metal of interest. So, for instance, the mining of copper will inevitably involve potential exposure to lead and arsenic. And the mining of gold will not only involve exposure to other metals and ores, but exposure to mercury, which is specifically imported for the purification process and then often discarded as waste.
So this discussion of the multiplicity of metals at each of these mining sites, from the mine, including the metals of interests and the collateral metals that are produced, to the metals that are brought in for the purification process, means that the issue of mixtures of metals is germane all over the world. That’s exactly the kind of issue that we’re trying to understand at the Tar Creek Superfund Site.
Interviewer: What are the implications of your studies and how do you hope they affect the future?
HOWARD: The big implications of the kind of work that we’re doing is number one, to demonstrate exactly what threats ensue from development and the industries that we employ to give us the products we need to live. Because a lot of these exposures are now occurring at their greatest in the developing world, one of my great hopes is that the developing world will be able to use this information during the development process, to leapfrog some of the worst excesses of our own society and go straight to a cleaner technology, a cleaner developmental model, that will allow their populations to reduce or prevent these exposures from happening from the beginning.
Interviewer: Can you discuss the costs of mining and how that ties in to public health?
HOWARD: The question of economics and how much these products cost is a very relevant one. And what it really means is that we have underestimated what the costs are. The human costs are for the environmental health threats that are produced when we mine these metals. In the future what we really need to do is to get a whole product life cycle cost when we embark on the next adventure to mine the next metal. Because that cost will allow us to recognize that preventing exposure by implementing, at the outset, a cleaner technology for mining metals or for making the next plastic will allow us to avoid the human cost down the line to defective communities, or the users of the products at the end.
Interviewer: Is there anything else you care to mention?
HOWARD: Yes, I guess there is an issue I should cover. There’s another aspect to our research, which is a very important dimension to environmental health. That is understanding the genetic variation in children and how some children might be genetically susceptible to the health effects of metals. We call that gene environment interaction. Nowadays, environmental health scientists recognize that most diseases are a complex interplay between our genes and our environment. We no longer think of disease as being either genes or environment. We’re also trying to understand that at the Tar Creek Superfund Site as part of our package of research.
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(Wikipedia) - Airplane "Aeroplane" and "Planes" redirect here. For other uses, see Airplane (disambiguation), Aeroplane (disambiguation), or Plane (disambiguation). Airplane/Aeroplane
Boeing 737-700 jet airliner
An airplane or aeroplane (informally plane) is a powered, fixed-wing aircraft that is propelled forward by thrust from a jet engine or propeller. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Most airplanes are flown by a pilot on board the aircraft, but some are designed to be remotely or computer-controlled.
In 1799, Sir George Cayley set forth the concept of the modern airplane. He was building and flying models of fixed-wing aircraft in 1803, and he built a successful passenger-carrying glider in 1853. Between 1867 and 1896 the German pioneer of human aviation Otto Lilienthal developed heavier-than-air flight. The Wright brothers flights in 1903 are recognized as "the first sustained and controlled heavier-than-air powered flight". Following WWI, aircraft technology continued to develop. Airplanes had a presence in all the major battles of World War II. The first jet aircraft was the German Heinkel He 178 in 1939. The first jet airliner, the de Havilland Comet, was introduced in 1952. The Boeing 707, the first widely successful commercial jet, was in commercial service for more than 50 years, from 1958 to 2010.
Contents
• 1 Etymology and usage
• 2 History
• 2.1 Antecedents
• 2.2 Early powered flights
• 2.3 Development of jet aircraft
• 3 Propulsion
• 3.1 Propeller engines
• 3.2 Jet engines
• 3.3 Electric engines
• 3.4 Rocket engines
• 3.5 Ramjet and scramjet engines
• 4 Design and manufacture
• 5 Characteristics
• 5.1 Airframe
• 5.2 Wings
• 5.2.1 Wing structure
• 5.2.2 Wing configuration
• 5.3 Fuselage
• 5.4 Wings vs. bodies
• 5.4.1 Flying wing
• 5.4.2 Blended wing body
• 5.4.3 Lifting body
• 5.5 Empennage and foreplane
• 5.6 Controls and instruments
• 6 Safety
• 7 See also
• 8 References
• 9 Bibliography
• 10 External links
Etymology and usage
First attested in English in the late 19th century (prior to the first sustained powered flight), the word airplane, like aeroplane, derives from the French aéroplane, which comes from the Greek ἀήρ (aēr), "air" and either Latin planus, "level", or Greek πλάνος (planos), "wandering". "Aéroplane" originally referred just to the wing, as it is a plane moving through the air. In an example of synecdoche, the word for the wing came to refer to the entire aircraft.
In the United States and Canada, the term "airplane" is used for powered fixed-wing aircraft. In the United Kingdom and most of the Commonwealth, the term "aeroplane" is usually applied to these aircraft.
History Main articles: Aviation history and First flying machine Antecedents
Many stories from antiquity involve flight, such as the Greek legend of Icarus and Daedalus, and the Vimana in ancient Indian epics. Around 400 BC in Greece, Archytas was reputed to have designed and built the first artificial, self-propelled flying device, a bird-shaped model propelled by a jet of what was probably steam, said to have flown some 200 m (660 ft). This machine may have been suspended for its flight.
Some of the earliest recorded attempts with gliders were those by the 9th-century poet Abbas Ibn Firnas and the 11th-century monk Eilmer of Malmesbury; both experiments injured their pilots. Leonardo da Vinci researched the wing design of birds and designed a man-powered aircraft in his Codex on the Flight of Birds (1502).
Le Bris and his glider, Albatros II, photographed by Nadar, 1868
In 1799, Sir George Cayley set forth the concept of the modern airplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control. Cayley was building and flying models of fixed-wing aircraft as early as 1803, and he built a successful passenger-carrying glider in 1853. In 1856, Frenchman Jean-Marie Le Bris made the first powered flight, by having his glider "L''Albatros artificiel" pulled by a horse on a beach. Then Alexander F. Mozhaisky also made some innovative designs. In 1883, the American John J. Montgomery made a controlled flight in a glider. Other aviators who made similar flights at that time were Otto Lilienthal, Percy Pilcher, and Octave Chanute.
Sir Hiram Maxim built a craft that weighed 3.5 tons, with a 110-foot (34-meter) wingspan that was powered by two 360-horsepower (270-kW) steam engines driving two propellers. In 1894, his machine was tested with overhead rails to prevent it from rising. The test showed that it had enough lift to take off. The craft was uncontrollable, which Maxim, it is presumed, realized, because he subsequently abandoned work on it.
In the 1890s, Lawrence Hargrave conducted research on wing structures and developed a box kite that lifted the weight of a man. His box kite designs were widely adopted. Although he also developed a type of rotary aircraft engine, he did not create and fly a powered fixed-wing aircraft.
Between 1867 and 1896 the German pioneer of human aviation Otto Lilienthal developed heavier-than-air flight. He was the first person to make well-documented, repeated, successful gliding flights.
Otto Lilienthal in mid-flight, c. 1895Early powered flights
The Wright brothers flights in 1903 are recognized by the Fédération Aéronautique Internationale (FAI), the standard setting and record-keeping body for aeronautics, as "the first sustained and controlled heavier-than-air powered flight". By 1905, the Wright Flyer III was capable of fully controllable, stable flight for substantial periods. The Wright brothers credited Otto Lilienthal as a major inspiration for their decision to pursue manned flight.
In 1906, Alberto Santos Dumont made what was claimed to be the first airplane flight unassisted by catapult and set the first world record recognized by the Aéro-Club de France by flying 220 meters (720 ft) in less than 22 seconds. This flight was also certified by the FAI.
An early aircraft design that brought together the modern monoplane tractor configuration was the Bleriot VIII design of 1908. It had movable tail surfaces controlling both yaw and pitch, a form of roll control supplied either by wing warping or by ailerons and controlled by its pilot with a joystick and rudder bar. It was an important predecessor of his later Bleriot XI Channel-crossing aircraft of the summer of 1909.
After much work the aircraft, A. Vlaicu nr. 1, was finished in 1909, and was test flown on June 17, 1910. From the first flight the airplane had no need of changes. The plane was made from a single aluminum spar 10 meters long which supported the entire aircraft, making it very easy to fly. Ten planes were made for the Romanian Air Force, being the second-ever military air force in the world.
World War I served as a testbed for the use of the airplane as a weapon. Airplanes demonstrated their potential as mobile observation platforms, then proved themselves to be machines of war capable of causing casualties to the enemy. The earliest known aerial victory with a synchronized machine gun-armed fighter aircraft occurred in 1915, by German Luftstreitkräfte Leutnant Kurt Wintgens. Fighter aces appeared; the greatest (by number of Aerial Combat victories) was Manfred von Richthofen.
Following WWI, aircraft technology continued to develop. Alcock and Brown crossed the Atlantic non-stop for the first time in 1919. The first international commercial flights took place between the United States and Canada in 1919.
Airplanes had a presence in all the major battles of World War II. They were an essential component of the military strategies of the period, such as the German Blitzkrieg or the American and Japanese aircraft carrier campaigns of the Pacific War.
Development of jet aircraft
The first ''operational'' jet aircraft was the German Heinkel He 178, which was tested in 1939. In 1943, the Messerschmitt Me 262, the first ''operational'' jet fighter aircraft, went into service in the German Luftwaffe. In October 1947, the Bell X-1 was the first aircraft to exceed the speed of sound.
The first jet airliner, the de Havilland Comet, was introduced in 1952. The Boeing 707, the first widely successful commercial jet, was in commercial service for more than 50 years, from 1958 to 2010. The Boeing 747 was the world''s biggest passenger aircraft from 1970 until it was surpassed by the Airbus A380 in 2005.
Propulsion See also: Powered aircraft and Aircraft engine Propeller enginesAn Antonov An-2 biplane
Smaller and older propeller planes make use of reciprocating engines (or piston engines) to turn a propeller to create thrust. The amount of thrust a propeller creates is determined by its disk area - the area in which the blades rotate. If the area is too small, efficiency is poor, and if the area is large, the propeller must rotate at a very low speed to avoid going supersonic and creating a lot of noise, and not much thrust. Because of this limitation, propellers are favored for planes which travel at below mach .5, while jets are a better choice above that speed. Propeller engines may be quieter than jet engines (though not always) and may cost less to purchase or maintain and so remain common on light general aviation aircraft such as the Cessna 172. Larger modern propeller planes such as the Dash 8 use a jet engine to turn the propeller, primarily because an equivalent piston engine in power output would be much larger and more complex.
Jet enginesThe Concorde supersonic transport aircraft
Jet aircraft are propelled by jet engines, which are used because the aerodynamic limitations of propellers do not apply to jet propulsion. These engines are much more powerful than a reciprocating engine for a given size or weight and are comparatively quiet and work well at higher altitude. Most modern jet planes use turbofan jet engines which balance the advantages of a propeller, while retaining the exhaust speed and power of a jet. This is essentially a ducted propeller attached to a jet engine, much like a turboprop, but with a smaller diameter. When installed on an airliner, it is efficient so long as it remains below the speed of sound (or subsonic). Jet fighters and other supersonic aircraft that do not spend a great deal of time supersonic also often use turbofans, but to function, air intake ducting is needed to slow the air down so that when it arrives at the front of the turbofan, it is subsonic. When passing through the engine, it is then re-accelerated back to supersonic speeds. To further boost the power output, fuel is dumped into the exhaust stream, where it ignites. This is called an afterburner and has been used on both pure jet aircraft and turbojet aircraft although it is only normally used on combat aircraft due to the amount of fuel consumed, and even then may only be used for short periods of time. Supersonic airliners (e.g. Concorde) are no longer in use largely because flight at supersonic speed creates a sonic boom which is prohibited in most heavily populated areas, and because of the much higher consumption of fuel supersonic flight requires.
Jet aircraft possess high cruising speeds (700 to 900 km/h (430 to 560 mph)) and high speeds for takeoff and landing (150 to 250 km/h (93 to 155 mph)). Due to the speed needed for takeoff and landing, jet aircraft use flaps and leading edge devices to control of lift and speed. Many also use thrust reversers to slow down the aircraft upon landing.
Electric engines
An electric aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, power beaming, or batteries. Currently, flying electric aircraft are mostly experimental prototypes, including manned and unmanned aerial vehicles, but there are some production models on the market already.
Rocket enginesBell X-1 in flight, 1947
In World War II, the Germans deployed the Me 163 Komet rocket-powered aircraft. The first plane to break the sound barrier in level flight was a rocket plane – the Bell X-1. The later North American X-15 broke many speed and altitude records and laid much of the groundwork for later aircraft and spacecraft design. Rocket aircraft are not in common usage today, although rocket-assisted take offs are used for some military aircraft. Recent rocket aircraft include the SpaceShipOne and the XCOR EZ-Rocket.
Ramjet and scramjet enginesArtist''s concept of X-43A with scramjet attached to the underside
A ramjet is a form of jet engine that contains no major moving parts and can be particularly useful in applications requiring a small and simple engine for high-speed use, such as with missiles. Ramjets require forward motion before they can generate thrust and so are often used in conjunction with other forms of propulsion, or with an external means of achieving sufficient speed. The Lockheed D-21 was a Mach 3+ ramjet-powered reconnaissance drone that was launched from a parent aircraft. A ramjet uses the vehicle''s forward motion to force air through the engine without resorting to turbines or vanes. Fuel is added and ignited, which heats and expands the air to provide thrust.
A scramjet is a supersonic ramjet and aside from differences with dealing with internal supersonic airflow works like a conventional ramjet. This type of engine requires a very high initial speed in order to work. The NASA X-43, an experimental unmanned scramjet, set a world speed record in 2004 for a jet-powered aircraft with a speed of Mach 9.7, nearly 7,500 miles per hour (12,100 km/h).
Design and manufacture Main article: Aerospace manufacturerAssembly line of the SR-71 Blackbird at Skunk Works, Lockheed Martin’s Advanced Development Programs (ADP).
Most airplanes are constructed by companies with the objective of producing them in quantity for customers. The design and planning process, including safety tests, can last up to four years for small turboprops or longer for larger planes.
During this process, the objectives and design specifications of the aircraft are established. First the construction company uses drawings and equations, simulations, wind tunnel tests and experience to predict the behavior of the aircraft. Computers are used by companies to draw, plan and do initial simulations of the aircraft. Small models and mockups of all or certain parts of the plane are then tested in wind tunnels to verify its aerodynamics.
When the design has passed through these processes, the company constructs a limited number of prototypes for testing on the ground. Representatives from an aviation governing agency often make a first flight. The flight tests continue until the aircraft has fulfilled all the requirements. Then, the governing public agency of aviation of the country authorizes the company to begin production.
In the United States, this agency is the Federal Aviation Administration (FAA), and in the European Union, European Aviation Safety Agency (EASA). In Canada, the public agency in charge and authorizing the mass production of aircraft is Transport Canada.
In the case of international sales, a license from the public agency of aviation or transport of the country where the aircraft is to be used is also necessary. For example, airplanes made by the European company, Airbus, need to be certified by the FAA to be flown in the United States, and airplanes made by U.S.-based Boeing need to be approved by the EASA to be flown in the European Union.
An Airbus A321 on final assembly line 3 in the Airbus plant at Hamburg Finkenwerder Airport.
Quieter planes are becoming more and more necessary due to the increase in air traffic, particularly over urban areas, as aircraft noise pollution is a major concern.
Small planes can be designed and constructed by amateurs as homebuilts. Other homebuilt aircraft can be assembled using pre-manufactured kits of parts that can be assembled into a basic plane and must then be completed by the builder.
There are few companies that produce planes on a large scale. However, the production of a plane for one company is a process that actually involves dozens, or even hundreds, of other companies and plants, that produce the parts that go into the plane. For example, one company can be responsible for the production of the landing gear, while another one is responsible for the radar. The production of such parts is not limited to the same city or country; in the case of large plane manufacturing companies, such parts can come from all over the world.
The parts are sent to the main plant of the plane company, where the production line is located. In the case of large planes, production lines dedicated to the assembly of certain parts of the plane can exist, especially the wings and the fuselage.
When complete, a plane is rigorously inspected to search for imperfections and defects. After approval by inspectors, the plane is put through a series of flight tests to assure that all systems are working correctly and that the plane handles properly. Upon passing these tests, the plane is ready to receive the "final touchups" (internal configuration, painting, etc.), and is then ready for the customer.
CharacteristicsAn IAI Heron - an unmanned aerial vehicle with a twin-boom configurationAirframe
The structural parts of a fixed-wing aircraft are called the airframe. The parts present can vary according to the aircraft''s type and purpose. Early types were usually made of wood with fabric wing surfaces, When engines became available for powered flight around a hundred years ago, their mounts were made of metal. Then as speeds increased more and more parts became metal until by the end of WWII all-metal aircraft were common. In modern times, increasing use of composite materials has been made.
Typical structural parts include:
• One or more large horizontal wings, often with an airfoil cross-section shape. The wing deflects air downward as the aircraft moves forward, generating lifting force to support it in flight. The wing also provides stability in roll to stop the aircraft from rolling to the left or right in steady flight.
The An-225 Mriya, which can carry a 250-tonne payload, has two vertical stabilisers.
• A fuselage, a long, thin body, usually with tapered or rounded ends to make its shape aerodynamically smooth. The fuselage joins the other parts of the airframe and usually contains important things such as the pilot, payload and flight systems.
• A vertical stabilizer or fin is a vertical wing-like surface mounted at the rear of the plane and typically protruding above it. The fin stabilizes the plane''s yaw (turn left or right) and mounts the rudder which controls its rotation along that axis.
• A horizontal stabilizer or tailplane, usually mounted at the tail near the vertical stabilizer. The horizontal stabilizer is used to stabilize the plane''s pitch (tilt up or down) and mounts the elevators which provide pitch control.
• Landing gear, a set of wheels, skids, or floats that support the plane while it is on the surface. On seaplanes the bottom of the fuselage or floats (pontoons) support it while on the water. On some planes the landing gear retracts during flight to reduce drag.
Wings
The wings of a fixed-wing aircraft are static planes extending either side of the aircraft. When the aircraft travels forwards, air flows over the wings which are shaped to create lift. This shape is called an airfoil and is shaped like a birds wing.
Wing structure
Airplanes have flexible wing surfaces which are stretched across a frame and made rigid by the lift forces exerted by the airflow over them. Larger aircraft have rigid wing surfaces which provide additional strength.
Whether flexible or rigid, most wings have a strong frame to give them their shape and to transfer lift from the wing surface to the rest of the aircraft. The main structural elements are one or more spars running from root to tip, and many ribs running from the leading (front) to the trailing (rear) edge.
Early airplane engines had little power and light weight was very important. Also, early airfoil sections were very thin, and could not have strong frame installed within. So until the 1930s most wings were too light weight to have enough strength and external bracing struts and wires were added. When the available engine power increased during the 1920s and 30s, wings could be made heavy and strong enough that bracing was not needed any more. This type of unbraced wing is called a cantilever wing.
Wing configuration Main articles: Wing configuration and WingCaptured Morane-Saulnier L wire-braced parasol monoplane
The number and shape of the wings varies widely on different types. A given wing plane may be full-span or divided by a central fuselage into port (left) and starboard (right) wings. Occasionally even more wings have been used, with the three-winged triplane achieving some fame in WWI. The four-winged quadruplane and other multiplane designs have had little success.
A monoplane has a single wing plane, a biplane has two stacked one above the other, a tandem wing has two placed one behind the other. When the available engine power increased during the 1920s and 30s and bracing was no longer needed, the unbraced or cantilever monoplane became the most common form of powered type.
The wing planform is the shape when seen from above. To be aerodynamically efficient, a wing should be straight with a long span from side to side but have a short chord (high aspect ratio). But to be structurally efficient, and hence light weight, a wing must have a short span but still enough area to provide lift (low aspect ratio).
At transonic speeds (near the speed of sound), it helps to sweep the wing backwards or forwards to reduce drag from supersonic shock waves as they begin to form. The swept wing is just a straight wing swept backwards or forwards.
Two Dassault Mirage G prototypes, one with wings swept
The delta wing is a triangle shape which may be used for a number of reasons. As a flexible Rogallo wing it allows a stable shape under aerodynamic forces, and so is often used for ultralight aircraft and even kites. As a supersonic wing it combines high strength with low drag and so is often used for fast jets.
A variable geometry wing can be changed in flight to a different shape. The variable-sweep wing transforms between an efficient straight configuration for takeoff and landing, to a low-drag swept configuration for high-speed flight. Other forms of variable planform have been flown, but none have gone beyond the research stage.
Fuselage Main article: fuselage
A fuselage is a long, thin body, usually with tapered or rounded ends to make its shape aerodynamically smooth. The fuselage may contain the flight crew, passengers, cargo or payload, fuel and engines. The pilots of manned aircraft operate them from a cockpit located at the front or top of the fuselage and equipped with controls and usually windows and instruments. A plane may have more than one fuselage, or it may be fitted with booms with the tail located between the booms to allow the extreme rear of the fuselage to be useful for a variety of purposes.
Wings vs. bodies Flying wing Main article: Flying wingThe US-produced B-2 Spirit is a strategic bomber. It has a flying wing configuration and is capable of intercontinental missions
A flying wing is a tailless aircraft which has no definite fuselage. Most of the crew, payload and equipment are housed inside the main wing structure.
The flying wing configuration was studied extensively in the 1930s and 1940s, notably by Jack Northrop and Cheston L. Eshelman in the United States, and Alexander Lippisch and the Horten brothers in Germany. After the war, a number of experimental designs were based on the flying wing concept, but the known difficulties remained intractable. Some general interest continued until the early 1950s but designs did not necessarily offer a great advantage in range and presented a number of technical problems, leading to the adoption of "conventional" solutions like the Convair B-36 and the B-52 Stratofortress. Due to the practical need for a deep wing, the flying wing concept is most practical for designs in the slow-to-medium speed range, and there has been continual interest in using it as a tactical airlifter design.
Interest in flying wings was renewed in the 1980s due to their potentially low radar reflection cross-sections. Stealth technology relies on shapes which only reflect radar waves in certain directions, thus making the aircraft hard to detect unless the radar receiver is at a specific position relative to the aircraft - a position that changes continuously as the aircraft moves. This approach eventually led to the Northrop B-2 Spirit stealth bomber. In this case the aerodynamic advantages of the flying wing are not the primary needs. However, modern computer-controlled fly-by-wire systems allowed for many of the aerodynamic drawbacks of the flying wing to be minimized, making for an efficient and stable long-range bomber.
Blended wing body Main article: Blended wingComputer-generated model of the Boeing X-48
Blended wing body aircraft have a flattened and airfoil shaped body, which produces most of the lift to keep itself aloft, and distinct and separate wing structures, though the wings are smoothly blended in with the body.
Thus blended wing bodied aircraft incorporate design features from both a futuristic fuselage and flying wing design. The purported advantages of the blended wing body approach are efficient high-lift wings and a wide airfoil-shaped body. This enables the entire craft to contribute to lift generation with the result of potentially increased fuel economy.
Lifting bodyThe Martin Aircraft Company X-24 was built as part of a 1963 to 1975 experimental US military program.Main article: Lifting body
A lifting body is a configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating non-lifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic, and hypersonic flight, or, spacecraft re-entry. All of these flight regimes pose challenges for proper flight stability.
Lifting bodies were a major area of research in the 1960s and 70s as a means to build a small and lightweight manned spacecraft. The US built a number of famous lifting body rocket planes to test the concept, as well as several rocket-launched re-entry vehicles that were tested over the Pacific. Interest waned as the US Air Force lost interest in the manned mission, and major development ended during the Space Shuttle design process when it became clear that the highly shaped fuselages made it difficult to fit fuel tankage.
Empennage and foreplaneCanards on the Saab Viggen
The classic airfoil section wing is unstable in flight and difficult to control. Flexible-wing types often rely on an anchor line or the weight of a pilot hanging beneath to maintain the correct attitude. Some free-flying types use an adapted airfoil that is stable, or other ingenious mechanisms including, most recently, electronic artificial stability.
But in order to achieve trim, stability and control, most fixed-wing types have an empennage comprising a fin and rudder which act horizontally and a tailplane and elevator which act vertically. This is so common that it is known as the conventional layout. Sometimes there may be two or more fins, spaced out along the tailplane.
Some types have a horizontal "canard" foreplane ahead of the main wing, instead of behind it. This foreplane may contribute to the lift, the trim, or control of the aircraft, or to several of these.
Controls and instrumentsA light aircraft (Robin DR400/500) cockpitFurther information: Fixed-wing aircraft § Aircraft controls and Fixed-wing aircraft § Cockpit instrumentation
Airplanes have complex flight control systems. The main controls allow the pilot to direct the aircraft in the air by controlling the attitude (roll, pitch and yaw) and engine thrust.
On manned aircraft, cockpit instruments provide information to the pilots, including flight data, engine output, navigation, communications and other aircraft systems that may be installed.
Safety Main article: Air safety
When risk is measured by deaths per passenger kilometer, air travel is approximately 10 times safer than travel by bus or rail. However, when using the deaths per journey statistic, air travel is significantly more dangerous than car, rail, or bus travel. Air travel insurance is relatively expensive for this reason- insurers generally use the deaths per journey statistic. There is a significant difference between the safety of airliners and that of smaller private planes, with the per-mile statistic indicating that airliners are 8.3 times safer than smaller planes.
Tags:Airbus A380, Airplane, American, Antonov, Atlantic, Birds, Boeing, Boeing 707, Boeing 747, Canada, Codex, Comet, Concorde, Dassault, European Union, France, French, Fédération, German, Germany, Greece, Greek, Hamburg, Ibn, Japanese, Jet, Landing, Lockheed, Mach, Maxim, NASA, Nadar, Northrop, Pacific, Plane, US, United Kingdom, United States, WWI, WWII, Wikipedia, World War I, World War II, Wright Flyer, Wright brothers
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What Does It Mean To Be In A Calorie Deficit?
You've likely seen the term calorie deficit or caloric deficit when reading about how to lose weight. But what does it mean to be in a calorie deficit, and how can you safely get there and lose weight in a healthy way?
A calorie deficit simply means that you're burning more energy — calories — than you're taking in. When you balance out the amount of calories you burn with the amount of calories that you eat and drink, you either end up with a calorie surplus, meaning you've eaten more than you've burned, or a calorie deficit, meaning you've burned more than you've eaten. A calorie deficit, also known as an energy deficit, leads to weight loss (via Verywell Fit).
You don't just burn calories through exercise: You burn them as you digest food, as your body regulates its temperature, and as you go about the small movements that make up daily living, like cooking, cleaning, and even working on the computer. You can calculate your basal metabolic rate — the calories you require to function optimally, based on your age, weight, gender, and daily activity level — using an online calculator like this one from ACE Fitness.
How big can your caloric deficit be?
Experts tend to agree that for most people, a calorie deficit of around 500 calories per day — 3,500 in a week — is a sustainable, safe way to lose weight gradually. In that deficit, your body begins using your stored fat as fuel. At most, you can try to create a deficit of 1,000 calories per day, which would lead to two pounds of fat loss per week, but any more than that is considered dangerous (via Women's Health). Regardless of what type of diet you're on — Paleo, vegan, keto, Mediterranean — you can create a calorie deficit.
You can reach a caloric deficit in two ways: By increasing your energy output, or by decreasing your energy input. Simply put, that means you're either exercising more or eating less. Experts agree that a combination of the two is the best way to sustain meaningful weight loss, since it's difficult to exercise long enough to burn a large amount of calories. But, after a certain amount of time eating less calories than you're burning, your body will slow your metabolism and actually drop the rate at which it uses energy (via Harvard Health Publishing).
Signs that you're cutting too many calories
As previously mentioned, eating too few calories can slow your metabolism. Yet getting too few calories on a routine basis can affect our body in a number of other ways too. According to WebMD, very low-calorie diets can induce side effects — including fatigue, nausea, diarrhea, and constipation. In more serious cases, some people may develop gallstones as a result of the body beginning to break down fat as an energy source. Additional signs that one is not getting the calories their body needs include hair loss, dizziness, and headaches (via SFGate).
Cutting too many calories can also increase one's risk for certain health conditions, reports Healthline. This can include everything from the common cold to malnutrition and fertility issues. Therefore, it's important to maintain a healthy, balanced calorie intake. Experts state that women should consume at least 1,000 calories per day and that men should consume a minimum of 1,200 calories daily (per SFGate). If you're taking in even lower amounts of calories due to a health condition, very low-calorie diets should be supervised by a physician.
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Transform Data
Transform data between time and frequency domains
Functions
fftTransform iddata object to frequency domain data
ifftTransform iddata objects from frequency to time domain
etfeEstimate empirical transfer functions and periodograms
spaEstimate frequency response with fixed frequency resolution using spectral analysis
spafdrEstimate frequency response and spectrum using spectral analysis with frequency-dependent resolution
Examples and How To
Transform Time-Domain Data in the App
Transform time-domain data to frequency-domain or frequency-response data.
Transform Frequency-Domain Data in the App
Transform frequency-domain input-output data to time-domain or frequency-response data.
Transform Frequency-Response Data in the App
Transform frequency-response data to frequency-domain input-output data or to frequency-response data with a different frequency resolution.
Concepts
Supported Data Transformations
Transform between time-domain and frequency-domain data at the command line.
Transforming Between Time and Frequency-Domain Data
Transform between time-domain and frequency-domain iddata objects at the command line.
Transforming Between Frequency-Domain and Frequency-Response Data
Transform between iddata and idfrd objects at the command line.
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Clinical trial identifiers for MSCs
A shiny app to explore the characterisation of mesenchymal stromal cells in clinical trial reports
Genever Lab
Department of Biology
University of York
York YO10 5DD
https://www.geneverlab.info/
DOI
Prepared by Emma Rand in support of:
Wilson, A. J., Rand, E., Webster, A. J., & Genever, P. G. (2021). Characterisation of mesenchymal stromal cells in clinical trial reports: analysis of published descriptors. Stem cell research & therapy, 12 (1), 360. https://doi.org/10.1186/s13287-021-02435-1
Abstract
Background: Mesenchymal stem or stromal cells are the most widely used cell therapy to date. They are heterogeneous, with variations in growth potential, differentiation capacity and protein expression profile depending on tissue source and production process. Nomenclature and defining characteristics have been debated for almost 20 years, yet the generic term “MSC” is used to cover a wide range of cellular phenotypes. Against a documented lack of definition of cellular populations used in clinical trials, our study evaluated the extent of characterization of the cellular population or study drug.
Methods: A literature search of clinical trials involving mesenchymal stem/stromal cells was refined to 84 papers upon application of pre-defined inclusion/exclusion criteria. Data were extracted covering background trial information including location, phase, indication, tissue source, and details of clinical cell population characterisation (expression of surface markers, viability, differentiation assays and potency/functionality assays). Descriptive statistics were applied, and tests of association between groups were explored using Fisher's Exact Test for Count Data with simulated p-value.
Results: Twenty-eight studies (33.3%) include no characterization data. Forty-five (53.6%) reported average values per marker for all cell lots used in the trial, and 11 (13.1%) studies included individual values per cell lot. Viability was reported in 57% of studies. Differentiation was discussed: osteogenesis (29% of papers) adipogenesis (27%) and chondrogenesis (20%); and other functional assays arose in 7 papers (8%). Extent of characterization was not related to clinical phase of development. Assessment of functionality was very limited and did not always relate to likely mechanism of action.
Conclusions: Extent of characterization was poor and variable. Our findings concur with those in other fields including bone marrow aspirate and platelet-rich plasma therapy. We discuss the potential implications of these findings for the use of mesenchymal stem or stromal cells in regenerative medicine, and the importance of characterization for transparency and comparability of literature.
Visualisation tools
Barplots for categorical variables
These barplots allow you to explore the number of trials for various categorical variables.
Where there are many categories, or category names are long, barplots with flipped axes are often clearer. You can select an additional categorical variable using the fill option. A test for the association between the x-axis variable and the fill variable is given below the plot.
Each point represents a publication - hover over the point for the publication id number. The extent of characterisation is given by the number of tests done without values being reported, with values being reported, or the sum of these (total).
Boxplots for categorical variable
A test for a difference in the extent of characterisations between different levels of the categorical variable is given below the plot.
The number of trials testing for an attribute and reporting values, testing without reporting values or not testing for each characterisation attribute.
In detail for each trial. The box indicates ISCT markers
Each point represents a publication - hover over the point for the publication id number.
Where there are no error bars - the publication reported average values for all cell lots used in the trial.
Where error bars are included - either the standard error on the average values for all cell lots used in the trial reported by the publication or the standard error calculated from individual values reported per cell lot.
ISCT markers
Other markers
The following markers were not reported in any paper: CD133, CD146, CD271, STRO-1, MSCA-1, SSEA-4
Figure 1. Literature search strategy and results. (A) The schematic shows search terms, refinements and exclusions used. Numbers refer to the total number of papers remaining at each stage. (B) Reported characteristics for MSCs in clinical research studies: data elements captured for this analysis. Basic information on the trial included clinical phase, indication, route of administration and mechanism(s) of action. Specifics of the cell source included donor details, tissue source and usage (allogeneic/autologous) and the descriptor used by the study: stem/stromal cells or other nomenclature. Aspects of characterization reported in the study were captured, focusing on assessment of viability, phenotypic profile, differentiation capacity and potency evaluations. Reference to ISCT minimal criteria for identification of MSC was also recorded.
Figure 2. Background trial information. (A) Origin of clinical research publications, ranked by number from each country represented in the analysis. (B) Clinical trials reported in literature by clinical phase, ranked by most commonly represented phase of clinical study. (C) Route of administration, ranked by most commonly used in the studies. (D) Indications addressed by the clinical studies, ranked by most commonly represented indication.
Figure 3. Background information on cells used in clinical trials. (A) Sources of tissue from which MSCs were derived. (B) Reported use of autologous and allogeneic MSCs (C) Nomenclature used to describe the cells used in the clinical trials.
Figure 4. Extent and stringency of characterization. (A) Number of articles reporting each category of characterization. (B) Stringency of characterization reported at each clinical phase of development (coloured as in A). (C) Number of phenotypic markers, and viability, evaluated in articles that reported values/averages.
Figure 5. Phenotypic characterization and viability. The minimal criteria recommended by ISCT for identification of MSC are shown between the black bars on the y-axis. (A) Analysis of individual markers reported in the clinical data set, showing whether an attribute was performed with results reported, whether it was performed but no results stated, or not mentioned in the study report. (B) Number of studies that addressed each attribute, defined by extent of reporting for each marker. Required expression or absence of a marker according to the ISCT recommendation is indicated on the y-axis.
Figure 6. Differentiation and other functionality assessments. (A) Frequency of functionality assessments. (B) Nomenclature (stem/stromal) in relation to potential mechanism of actions relevant to each study indication. (C) Evaluation of MSC differentiation capacity (multi-potentiality) in relation to the mechanism of action anticipated for each study.
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video播放器全屏兼容方案
Github上有两个video的插件维护的比较积极，在Github里搜索video，排序选择最高star的，关于video播放器的分别是video.jsmediaelement，虽然video.js的数目很多，但我想只是因为它这个项目的名称起得好，所以大家搜索video的内容时，Github总是第一位推荐，而mediaelement却没法出现在Github的那个推荐搜索里。
我们的网站使用的是mediaelement集成的，里面有很多很实用的插件，其中关于video全屏的方案兼容性做得很好，比起video.js那个插件，不支持ios Safari全屏播放，考虑PC方面的比较多，而mediaelement的那个Fullscreen.js就写得比较全了。我提取了里面的一些代码，总结如下：
1.首先检查是否支持浏览器自带的全屏方法。
github上有一个fullscreen.js的api很全，mediaelement就是使用这个类似的方法，当然video.js这个也是使用上面这个。
用法很简单，引入js后，screenfull 就是一个全局变量。我们可以通过定义一个按钮点击后出发这个全屏api.代码如下：
if (screenfull.enabled) {
screenfull.toggle(target);
screenfull.on('change', () = >{
if (screenfull.isFullscreen) {
$('body').addClass('fullscreen');
} else {
$('body').removeClass('fullscreen');
}
});
}
还有更多用法可以参考官网：https://github.com/sindresorhus/screenfull.js
2.当不支持上面的用法时，我们还可以继续检测是否支持苹果Safari自带的video全屏api。
var element = $('#video video')[0]; //video DOM
if (element.webkitEnterFullscreen || element.enterFullScreen) {
element.webkitEnterFullscreen && element.webkitEnterFullscreen();
element.enterFullScreen && element.enterFullScreen();
}
为什么这个代码有用而且必须加呢？因为iphone上，微信和Safari都不支持第一种的浏览器api，但支持这个全屏api，所以我们使用这个api实现了iphone下面video标签的全屏。
3.当然是以上两种方法都不支持的情况下，我们就只能模拟video全屏了，模拟的意思就是只能实现样式上看起来全屏，但实际浏览器自带的头部和尾部都没法隐藏，不像上面这两种api，当全屏状态下，浏览器的上下导航是会隐藏的。
function mockFullscreen(curEl) {
var wrapperEl = $('#video .video_wrap');
var playerEl = $('#video video');
if (curEl.hasClass('normal')) {
playerObj.fullscreen = false;
$('body').removeClass('fullscreen');
curEl.removeClass('normal');
} else {
playerObj.fullscreen = true;
$('body').addClass('fullscreen');
curEl.addClass('normal');
}
}
所以，模拟video控件的全屏，就是上面这三种写法了，结合起来就能实现各个平台的全屏效果了。
完整代码：
<div id="video">
<button class="fscreen J_play">播放视频</button>
<button class="fscreen J_fscreen">video全屏</button>
<div class="video_wrap"><video id="video_js_palyer" preload="auto" autoplay="autoplay" playsinline="true" webkit-playsinline="true" x-webkit-airplay="true" x5-video-player-type="h5" x5-video-player-fullscreen="true" x5-video-orientation="portraint" x5-video-ignore-metadata="true" style="width: 100%; object-fit: contain;" src="//auto.pcvideo.com.cn/pcauto/vpcauto/2018/07/05/1530785606876-vpcauto-78188-1_3.mp4"></video></div>
</div>
<script type="text/javascript" src="https://js.3conline.com/pcvideo/2017/wap/live/v2/fullscreen.js" charset="gbk"></script>
<script src="https://js.3conline.com/min/temp/v1/lib-jquery1.10.2.js"></script>
<script type="text/javascript">
var Features = {};
var target = $('#video')[0]; // Get DOM element from jQuery collection
var element = $('#video video')[0];
var NAV = window.navigator;
var UA = NAV.userAgent.toLowerCase();
Features.IS_IOS = /ipad|iphone|ipod/i.test(UA) && !window.MSStream;
// iOS
Features.hasiOSFullScreen = (element.webkitEnterFullscreen !== undefined);
// W3C
Features.hasNativeFullscreen = (element.requestFullscreen !== undefined);
// OS X 10.5 can't do this even if it says it can :(
if (Features.hasiOSFullScreen && /mac os x 10_5/i.test(UA)) {
Features.hasNativeFullscreen = false;
Features.hasiOSFullScreen = false;
}
var IS_CHROME = /chrome/i.test(UA);
if (IS_CHROME) {
Features.hasiOSFullScreen = false;
}
var playerObj = {};
$('.J_play').on('click',function(){
var self = $(this);
if(!self.hasClass('playing')){
element.play();
self.addClass('playing');
}else{
element.pause();
self.removeClass('playing');
}
});
element.addEventListener('pause',function(){
if(!$('.J_play').hasClass('playing')){
$('.J_play').addClass('playing');
}
});
element.addEventListener('pause',function(){
if($('.J_play').hasClass('playing')){
$('.J_play').removeClass('playing');
}
});
element.addEventListener('ended',function(){
if($('.J_play').hasClass('playing')){
$('.J_play').removeClass('playing');
}
})
$(document).on('click','.J_fscreen',function(){
var curEl = $(this);
curEl.html('触发全屏');
if(!$('.J_play').hasClass('playing')){
$('.J_play').trigger('click');
}
enterFullScreen();
function enterFullScreen(){
if(Features.IS_IOS && Features.hasiOSFullScreen && typeof element.webkitEnterFullscreen === 'function' && element.canPlayType('video/mp4')){
// alert(2);
Features.isiOSFullScreen = true;
console.log('ios全屏');
setTimeout(function(){
element.webkitEnterFullscreen();
},0);
return;
}
fakeFullScreen();
}
function fakeFullScreen(){
if(Features.isiOSFullScreen) return;
if (screenfull.enabled) {
console.log('浏览器全屏');
screenfull.toggle(target);
screenfull.on('change', () => {
if(screenfull.isFullscreen){
playerObj.isFullScreen = true;
$('body').addClass('body_fullscreen');
}else{
playerObj.isFullScreen = false;
$('body').removeClass('body_fullscreen');
}
});
}else{
console.log('伪全屏');
_mockFullscreen();
}
}
function exitFullscreen(){
fakeFullScreen();
}
function _mockFullscreen() {
var wrapperEl = $('#video .video_wrap');
var playerEl = $('#video video');
if (curEl.hasClass('fullscreen_on')) {
playerObj.isFullScreen = false;
$('body').removeClass('body_fullscreen');
curEl.removeClass('fullscreen_on');
} else {
playerObj.isFullScreen = true;
$('body').addClass('body_fullscreen');
curEl.addClass('fullscreen_on');
}
}
})
</script>
演示：http://caibaojian.com/demo/2018/8/video-fullscreen.html
原创文章：video播放器全屏兼容方案 ，未经许可，禁止转载，©版权所有
原文出处：前端开发博客 (http://caibaojian.com/video-screenfull.html)
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MENU
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Why will laser cleaning become the general trend?
2020-05-14source:access:627
The traditional industrial cleaning methods mainly include high-pressure water, chemical reagents, ultrasonic waves, and mechanical polishing. However, these cleaning methods have problems such as damage to the substrate, poor working environment, pollution, partial cleaning, and high cleaning costs. With the intensification of environmental pollution, scholars from various countries are actively developing energy-saving, environmentally friendly and efficient new cleaning technologies. Because laser cleaning technology has multiple advantages such as low damage to substrate materials, high cleaning accuracy, zero emissions and no pollution, it is gradually being valued and favored by academia and industry. There is no doubt that the application of laser cleaning technology to the cleaning of dirt on metal surfaces has very broad prospects.
Development history and current status of laser cleaning technology:
In the 1960s, the famous physicist Schawlow first proposed the concept of laser cleaning, and then applied the technology to the repair and maintenance of ancient books. The decontamination range of laser cleaning abroad is very wide, from the thick rust layer to the fine particles on the surface of the object, including the cleaning of cultural relics, the removal of rubber dirt on the tire mold surface, the removal of silicone oil contaminants on the surface of the gold film, and microelectronics. High-precision cleaning in the industry. In China, laser cleaning technology really began in 2004, and China began to invest a lot of manpower and material resources to strengthen the research on laser cleaning technology. In the past decade, with the development of advanced lasers, from inefficient and bulky carbon dioxide lasers to light and compact fiber lasers; from continuous output lasers to short pulse lasers with nanoseconds or even picoseconds and femtoseconds; from visible light output To the output of long-wave infrared light and short-wave ultraviolet light ... lasers have developed by leaps and bounds in terms of energy output, wavelength range, or laser quality and energy conversion efficiency. The development of lasers has naturally promoted the rapid development of laser cleaning technology. Laser cleaning technology has achieved fruitful results in theory and application.
The principle of laser cleaning technology:
The process of pulsed laser cleaning depends on the characteristics of the light pulses generated by the laser and is based on the photophysical reaction caused by the interaction between the high-intensity light beam, the short-pulse laser and the contamination layer. The physical principle can be summarized as follows (Figure 1):
A) The beam emitted by the laser is absorbed by the pollution layer on the surface to be treated;
B) Absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), generating shock waves;
C) Shock waves make pollutants debris and removed;
D) The light pulse width must be short enough to avoid heat accumulation that would damage the treated surface;
E) Experiments show that when there are oxides on the metal surface, plasma is generated on the metal surface.
Plasma is only generated when the energy density is above the threshold, which depends on the contaminated layer or oxide layer being removed. This threshold effect is very important for effective cleaning while ensuring the safety of the substrate material. There is a second threshold for the appearance of plasma. If the energy density exceeds this threshold, the base material will be destroyed. In order to carry out effective cleaning under the premise of ensuring the safety of the substrate material, the laser parameters must be adjusted according to the situation, so that the energy density of the light pulse is strictly between two thresholds.
Advantages of laser cleaning:
Compared with traditional cleaning methods such as mechanical friction cleaning, chemical corrosion cleaning, liquid solid strong impact cleaning, and high-frequency ultrasonic cleaning, laser cleaning has obvious five advantages:
Environmental protection advantages: Laser cleaning is a "green" cleaning method, without the use of any chemicals or cleaning fluids. The cleaned waste is basically solid powder, small in size, easy to store, recyclable, no photochemical reaction, no Will cause pollution.
Effect advantage: The traditional cleaning method is often contact cleaning, which has mechanical force on the surface of the cleaning object, the surface of the damaged object or the cleaning medium is attached to the surface of the object to be cleaned, and cannot be removed, resulting in secondary pollution Grinding and non-contact, no thermal effects will not damage the substrate, making these problems solved.
Control advantages: The laser can be transmitted through the optical fiber, cooperate with the robot hand and the robot, and realize the long-distance operation conveniently.
Convenient advantage: laser cleaning can remove various types of contaminants on the surface of various materials, reaching a degree of cleanliness that cannot be achieved by conventional cleaning. It can also selectively clean contaminants on the surface of the material without damaging the surface of the material.
Cost advantage: laser cleaning speed is fast, high efficiency, save time; although the initial investment of laser cleaning system is high at the current stage, the cleaning system can be used stably for a long time, the operating cost is low, and more importantly, it can be easily automated . It is foreseeable that the cost of the laser cleaning system will be greatly reduced in the future, thereby further reducing the cost of using laser cleaning technology.
Classification of laser cleaning technology:
The methods of laser cleaning can be divided into the following three categories:
1. Laser Dry Cleaning
Using laser radiation to directly decontaminate, after the laser is absorbed by objects or dirt particles, it generates vibration, which separates the substrate and the pollutants. In the laser dry cleaning, there are two main ways to remove dirt particles: One is the instantaneous thermal expansion of the substrate surface, which generates vibrations to remove the particles adsorbed on the surface. The other is the thermal expansion of the particles themselves, causing the particles to leave the surface of the substrate.
2. Laser wet cleaning
Laser wet cleaning is to uniformly cover the surface of the substrate to be cleaned with a layer of liquid dielectric film, and then use laser radiation to remove stains. According to the absorption of laser light by dielectric film and substrate, wet cleaning can be divided into strong substrate absorption, strong dielectric film absorption and dielectric film substrate absorption. When the strong substrate absorbs, after the substrate absorbs the laser energy, the heat is transferred to the liquid dielectric film, the liquid layer at the interface between the substrate and the liquid is overheated and the liquid layer and the stain are removed together.
3. Laser + inert gas cleaning
At the same time of laser radiation, the surface of the workpiece is blown with inert gas. When the contaminants are peeled from the surface, they are blown away from the surface by the gas, avoiding the contamination and oxidation of the clean surface.
CYCJET is a brand name of Yuchang Industrial Company Limited. As a manufacturer, CYCJET have more than ten years’ experience for wholesaler and retailer of different types of handheld inkjet printing solution, Laser printing solution, portable marking solution in Shanghai China.
Contact Person: David Guo
Telephone: +86-21-59970419 ext 8008
MOB:+86-139 1763 1707
Email: [email protected]
SHANGHAI YUCHANG INDUSTRIAL CO., LIMITED
ADD.: 1/F BLDG 4, NO. 333 HUAGAO RD.,HUATING IND. ZONE, JIADING DIST., SHANGHAI (201816) P.R.C.
TEL: +86 21 5997 0419 FAX:+86 21 5997 1610 MOB:+ 86-139 1763 1707(Whatsapp) Email:[email protected] SiteMap
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| 0.939709 |
Menopause Symptoms And Natural Remedies That You Ought to Know
4036889922 f63cf7986b m Menopause Symptoms And Natural Remedies That You Ought to Know
Menopause is not a disease, but it is new phase in an older woman’s life which usually causes the ovulation to cease and as a result Menopause stops. This is a natural phenomenon in life and it starts many years before menopause symptoms actually begin to show. The levels of the hormones may vary for many years before eventually becoming so little that the endometrium remains thin and does not bleed. Generally the ovaries start to slow the production of hormones like estrogen, testosterone and progesterone. The low estrogen levels may lead to changes in collagen production that may affect hair, nails, skin and tendons. The skin may become thinner, dryer, less elastic, more prone to bruising and skin itching may also occur. The foremost symptoms of menopause are, night sweats, insomnia, hot flushes, palpitations, joint aches, vaginal dryness and headaches. Due to the shortage of estrogen it thereby contributes to developing heart disease, osteoporosis, tooth decay, cardiovascular problems and a range of vaginal complications. Menopause generally occurs around 51 years, but it can occur much earlier or later. If it occurs before the age of 45 then it is called early menopause and before the age of 40 it is called as premature menopause. Premenopause is the phase from the beginning of menopausal indication to the post menopause. Post menopause subsequently occurs in the last period. Usually it is defined as more than 12 months when no periods in someone occurs and with intact ovaries. Menopause symptoms are as follows – 1. Hot Flashes 2. Sleep Problems 3. Bladder Problems 4. Aches and Pains 5. Skin Problems 6. Vaginal Dryness 7. Emotional imbalances. The Home Remedies are – To increase your levels of estrogen try increasing your consumption of plants which contain estrogenic substances. To reduce the Hot Flashes one will have to drink at least 8 glasses of water everyday. Then use 2 teaspoons of cohosh root tincture, 1 spoon of don quai root tincture, 1 spoon of sarsaparilla tincture, 1 spoon of licorice root tincture, 1 spoon of chaste tree tincture, 1 spoon ginseng root tincture. Then mix all the ingredients well and take 3 drops a day. For skin one may use 2 ounces aloe Vera gel and blossom water. 1 tablespoon of wine vinegar can be used to bring a glow in the skin. 6 drops rose eranium essential oil and few drops of sandalwood essential oil. There are various creams that can be applied to prevent any type of irritation. Even oil application like almond oil is an effective home remedy.
You Need to Know About These Stress Symptoms
5590047933 7f78e3e07b m You Need to Know About These Stress Symptoms
Even though stress doesn’t affect everyone the same way, there are some symptoms of it that are fairly common. The signs of stress will affect and show in various ways on our lives including our physical, mental and social health. Stress and life come hand in hand because we are always bombarded with various demands from family, friends and bosses but we should learn to control our stress levels. When your stress levels appear too much to bear with greater frequency of the following stress symptoms affecting your life, you are well advised to find help from family and friends as well as from a psychiatric, if needed.
Weight gain or loss could be caused from stress. You may find yourself skipping meals because you feel too stressed to eat, this is not a great way to lose weight because you are depriving your body of the necessary nutrition it needs to function. Some people are susceptible to eating disorders that are related to their stress levels and can reduce weight but not in a healthy natural way. Even more common is overeating, or eating the wrong kinds of foods, which cause weight gain. To feel better emotionally some people use food. You may find that it is hard to cut back on your calories if you are consistently eating. By managing your stress you should be able to take steps to manage your eating habits. Your personal and professional relationships also suffer mainly because of your difficulty with controlling your moods due to abnormal levels of stress. Your temper can also be intolerant of others so much so that being rude has now become part of your daily life. Stress adversely impacts on the way we react to situations like big arguments over small matters, road rage over trivial traffic infractions and extreme frustrations over irrelevant issues. This, in turn, can make your relationships more difficult and create even more stress, so it’s important to find ways to manage stress that’s causing you to act out in ways that may be inappropriate.
People often hold stress in different parts of their bodies, which can cause a variety of symptoms. In some cases, it can cause muscle aches, especially in the back, shoulders and neck. If your area to hold tension is your neck, for example, you are likely to experience frequent tightness and stiffness in the area. Back pain is another physical ailment commonly associated with stress though it can be the result of other physical conditions too. When you begin to notice stress impacting a certain body part, it’s a good idea to try deep breathing to reduce the pain you’ll experience.
Just as there are many symptoms of stress, such as the ones we’ve covered here, there are many ways to deal with it. It’s better if you can find a way to reduce stress or change the circumstances that are causing it, rather than only treating the symptoms. Aspirin can only treat the headache not what’s causing the headache. Find the cause, find the cure.
Alzheimers Disease Symptoms
131986788 238f3f8718 m Alzheimers Disease Symptoms
Alzheimer’s Disease is a common form of dementia that can be devastating to someone progressing through the stages of it and to loved ones who have to witness the degeneration of their mental faculties. Alzheimer’s Disease affects all of us, from close family and friends to strangers and famous figures like Ronald Reagan. While Alzheimer’s is an incurable disease and there are no treatments known to stop its progression, it’s important to know how to detect it early on.
All of us experience faulty memory and general malfunctions in our thinking every now and then, but the symptoms of Alzheimer’s exhibit this to such a degree that it interferes with daily living. Alzheimer’s Disease symptoms include poor retention of recently acquired knowledge, problems with developing or following plans, forgetting how to do simple daily tasks, confusion about time and location, trouble with visual and spatial perception, losing language ability, misplacing things and being unable to retrace steps, seriously poor judgment, withdrawal and significant changes in disposition. It’s normal to have occasional incidents that are reminiscent of these symptoms, but they’re more likely to be Alzheimer’s Disease symptoms when a generally older individual can’t live their life the way they used to because of excessive forgetfulness or impaired thinking.
If you or someone in your life appears to exhibit Alzheimer’s Disease symptoms, getting checked out right away can help patients plan better for the future. One way to alleviate symptoms involves medication that helps brain functioning by boosting levels of acetylcholine, a neurotransmitter associated with memory or inhibiting glutamate, a chemical that over-actively controls the amount of substances that enter brain nerve cells in Alzheimer’s patients. Other than medicine, usually Alzheimer’s Disease is “treated” by making sure that patients engage in an active lifestyle with a healthy diet and social relationships. Alzheimer’s patients can also get a head start on dealing with things like financial issues and housing and care services so that they and their loved ones will be provided for.
Even if the condition is untreatable, it’s possible to relieve Alzheimer’s Disease symptoms to provide a better quality of life for patients and the people in their lives. After all, we should all make the best of the time that we have, and sometimes things happen in life to make us more aware of that fact.
High Blood Pressure – Natural Treatment, Causes And Symptoms
2436478104 4563c0c060 m High Blood Pressure Natural Treatment, Causes And Symptoms
Heart pumps out the blood to all the tissues and organs of the body through the vessels called arteries. When the blood flows in the arteries with pressure it results into hypertension which is also known as high blood pressure. Normal measurement of blood pressure is 120/80 and when this measurement goes to 140/90 or above then this condition is considered to be high blood pressure. There are many causes of blood pressure and sometimes it is the result of another disease. In that case when the root cause is treated the blood pressure returns to its normal position. This condition may be kidney disease which is chronic, pregnancy, dysfunction of thyroid, intake of birth control pills, addiction of alcohol, tumors and coarctation of the aorta. Many factors, that cause high blood pressure is still unknown. But some factors that contributes to the cause of high blood pressure are age, race, overweight, hereditary, intake of excess sodium, use of alcohol, lack of exercise and also due to intake of certain medications. Some of the major symptoms of high blood pressure are-blurred vision, Nausea, dizziness and constant headache. Sometimes the high blood pressure show no symptoms but cause progressive damage to heart, blood vessels and other organs. If the degree of high blood pressure is high then it requires immediate hospitalization. It is very necessary to lower the blood pressure to prevent stroke or brain hemorrhage. Blood pressure can be reduced to a great extent through nutritional changes. It is necessary to increase the intake of fruits and vegetables. It not only reduces our fat and cholesterol but also reduces the blood pressure with loss in weight also. 1. Restrict the intake of sugar, salt, refined foods, junk foods, caffeine, dairy products and fried products. 2. Drink plenty of water 3. Avoid food sensitivities 4. Increase the intake of fresh, whole, unrefined, unprocessed foods. It is necessary to include vegetables, fruits, garlic, onion, olive oil, cold water fish, soy, beans and whole grains in your diet. It will finally lower the blood pressure and weight is also reduced. 5. It is must to reduce the intake of sodium in your diet. It will help in reducing the blood pressure. This fact is known to almost every educated person. 6. Some herbal medicines also reduce our blood pressure. 7. To lower the blood pressure flaxseed meal is also a best option. Grind 2-4 tablespoon and take it daily. 8. Vitamin C, calcium and coenzyme are also recommended top lower the blood pressure.
Herpes Ointment Can Alleviate Painful Symptoms
4394963502 812685929a m Herpes Ointment Can Alleviate Painful Symptoms
It is often possible to treat the painful symptoms of herpes with over the counter medications such as aspirin, acetaminophen and ibuprofen. However, when the discomfort becomes intolerable many people will use a herpes ointment for relief.
Acyclovir ointment is a prescription antiviral topical medication that is indicated for use with initial genital herpes breakouts and for treatment of individuals at risk for complications from herpes due to compromised immune systems. Acyclovir 5% ointment contains 50 mg of acyclovir. In clinical trials of initial herpes infections, side effects included mild burning and stinging at the site of application. Studies have also shown that acyclovir may reduce healing time by 5%. This medication is for use on the skin only, and should not be used in the eyes. For recurring genital herpes outbreaks, lidocaine ointment can be used to alleviate pain. Lidocaine will provide temporary relief of symptoms, but will not reduce the duration of the herpes outbreak or prevent future outbreaks. In some individuals it may cause the area to become overly sensitive. As with any medication there is the potential of an allergic reaction. People with a known allergy to lidocaine should not use this ointment. If an allergic reaction occurs, treatment should be discontinued and the individual should consult with a physician. Some research has shown that ointments containing propolis, a substance made by honey bees, may help heal herpes sores, and that it may be more effective than ointments made with acyclovir. In a study, propolis ointment was applied to the sores four times daily. After 10 days, 24 of the 30 patients using it reported that their sores had healed, as compared to only 14 of the 30 patients using acyclovir. Propoalis has not been approved by the U. S. Food and Drug Administration for the treatment of herpes. Currently, it is available as a nutritional supplement. Using herpes ointment can help to lessen the pain and discomfort of an outbreak, but will not prevent future outbreaks. Patients should consult with their doctor before beginning any new treatment.
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Code Snippets
This document contains code for some of the important classes, listed as below:
PgAdminModule
PgAdminModule is inherited from Flask.Blueprint module. This module defines a set of methods, properties and attributes, that every module should implement.
class PgAdminModule(Blueprint):
"""
Base class for every PgAdmin Module.
This class defines a set of method and attributes that
every module should implement.
"""
def __init__(self, name, import_name, **kwargs):
kwargs.setdefault('url_prefix', '/' + name)
kwargs.setdefault('template_folder', 'templates')
kwargs.setdefault('static_folder', 'static')
self.submodules = []
self.parentmodules = []
super(PgAdminModule, self).__init__(name, import_name, **kwargs)
def create_module_preference():
# Create preference for each module by default
if hasattr(self, 'LABEL'):
self.preference = Preferences(self.name, self.LABEL)
else:
self.preference = Preferences(self.name, None)
self.register_preferences()
# Create and register the module preference object and preferences for
# it just before the first request
self.before_app_first_request(create_module_preference)
def register_preferences(self):
# To be implemented by child classes
pass
def register(self, app, options):
"""
Override the default register function to automagically register
sub-modules at once.
"""
self.submodules = list(app.find_submodules(self.import_name))
super(PgAdminModule, self).register(app, options)
for module in self.submodules:
module.parentmodules.append(self)
if app.blueprints.get(module.name) is None:
app.register_blueprint(module)
app.register_logout_hook(module)
def get_own_stylesheets(self):
"""
Returns:
list: the stylesheets used by this module, not including any
stylesheet needed by the submodules.
"""
return []
def get_own_messages(self):
"""
Returns:
dict: the i18n messages used by this module, not including any
messages needed by the submodules.
"""
return dict()
def get_own_javascripts(self):
"""
Returns:
list: the javascripts used by this module, not including
any script needed by the submodules.
"""
return []
def get_own_menuitems(self):
"""
Returns:
dict: the menuitems for this module, not including
any needed from the submodules.
"""
return defaultdict(list)
def get_panels(self):
"""
Returns:
list: a list of panel objects to add
"""
return []
def get_exposed_url_endpoints(self):
"""
Returns:
list: a list of url endpoints exposed to the client.
"""
return []
@property
def stylesheets(self):
stylesheets = self.get_own_stylesheets()
for module in self.submodules:
stylesheets.extend(module.stylesheets)
return stylesheets
@property
def messages(self):
res = self.get_own_messages()
for module in self.submodules:
res.update(module.messages)
return res
@property
def javascripts(self):
javascripts = self.get_own_javascripts()
for module in self.submodules:
javascripts.extend(module.javascripts)
return javascripts
@property
def menu_items(self):
menu_items = self.get_own_menuitems()
for module in self.submodules:
for key, value in module.menu_items.items():
menu_items[key].extend(value)
menu_items = dict((key, sorted(value, key=attrgetter('priority')))
for key, value in menu_items.items())
return menu_items
@property
def exposed_endpoints(self):
res = self.get_exposed_url_endpoints()
for module in self.submodules:
res += module.exposed_endpoints
return res
NodeView
The NodeView class exposes basic REST APIs for different operations used by the pgAdmin Browser. The basic idea has been taken from Flask’s MethodView class. Because we need a lot more operations (not, just CRUD), we can not use it directly.
class NodeView(View, metaclass=MethodViewType):
"""
A PostgreSQL Object has so many operaions/functions apart from CRUD
(Create, Read, Update, Delete):
i.e.
- Reversed Engineered SQL
- Modified Query for parameter while editing object attributes
i.e. ALTER TABLE ...
- Statistics of the objects
- List of dependents
- List of dependencies
- Listing of the children object types for the certain node
It will used by the browser tree to get the children nodes
This class can be inherited to achieve the diffrent routes for each of the
object types/collections.
OPERATION | URL | HTTP Method | Method
---------------+-----------------------------+-------------+--------------
List | /obj/[Parent URL]/ | GET | list
Properties | /obj/[Parent URL]/id | GET | properties
Create | /obj/[Parent URL]/ | POST | create
Delete | /obj/[Parent URL]/id | DELETE | delete
Update | /obj/[Parent URL]/id | PUT | update
SQL (Reversed | /sql/[Parent URL]/id | GET | sql
Engineering) |
SQL (Modified | /msql/[Parent URL]/id | GET | modified_sql
Properties) |
Statistics | /stats/[Parent URL]/id | GET | statistics
Dependencies | /dependency/[Parent URL]/id | GET | dependencies
Dependents | /dependent/[Parent URL]/id | GET | dependents
Nodes | /nodes/[Parent URL]/ | GET | nodes
Current Node | /nodes/[Parent URL]/id | GET | node
Children | /children/[Parent URL]/id | GET | children
NOTE:
Parent URL can be seen as the path to identify the particular node.
i.e.
In order to identify the TABLE object, we need server -> database -> schema
information.
"""
operations = dict({
'obj': [
{'get': 'properties', 'delete': 'delete', 'put': 'update'},
{'get': 'list', 'post': 'create'}
],
'nodes': [{'get': 'node'}, {'get': 'nodes'}],
'sql': [{'get': 'sql'}],
'msql': [{'get': 'modified_sql'}],
'stats': [{'get': 'statistics'}],
'dependency': [{'get': 'dependencies'}],
'dependent': [{'get': 'dependents'}],
'children': [{'get': 'children'}]
})
@classmethod
def generate_ops(cls):
cmds = []
for op in cls.operations:
idx = 0
for ops in cls.operations[op]:
meths = []
for meth in ops:
meths.append(meth.upper())
if len(meths) > 0:
cmds.append({
'cmd': op, 'req': (idx == 0),
'with_id': (idx != 2), 'methods': meths
})
idx += 1
return cmds
# Inherited class needs to modify these parameters
node_type = None
# Inherited class needs to modify these parameters
node_label = None
# This must be an array object with attributes (type and id)
parent_ids = []
# This must be an array object with attributes (type and id)
ids = []
@classmethod
def get_node_urls(cls):
assert cls.node_type is not None, \
"Please set the node_type for this class ({0})".format(
str(cls.__class__.__name__))
common_url = '/'
for p in cls.parent_ids:
common_url += '<{0}:{1}>/'.format(str(p['type']), str(p['id']))
id_url = None
for p in cls.ids:
id_url = '{0}<{1}:{2}>'.format(
common_url if not id_url else id_url,
p['type'], p['id'])
return id_url, common_url
def __init__(self, **kwargs):
self.cmd = kwargs['cmd']
# Check the existance of all the required arguments from parent_ids
# and return combination of has parent arguments, and has id arguments
def check_args(self, **kwargs):
has_id = has_args = True
for p in self.parent_ids:
if p['id'] not in kwargs:
has_args = False
break
for p in self.ids:
if p['id'] not in kwargs:
has_id = False
break
return has_args, has_id and has_args
def dispatch_request(self, *args, **kwargs):
http_method = flask.request.method.lower()
if http_method == 'head':
http_method = 'get'
assert self.cmd in self.operations, \
'Unimplemented command ({0}) for {1}'.format(
self.cmd,
str(self.__class__.__name__)
)
has_args, has_id = self.check_args(**kwargs)
assert (
self.cmd in self.operations and
(has_id and len(self.operations[self.cmd]) > 0 and
http_method in self.operations[self.cmd][0]) or
(not has_id and len(self.operations[self.cmd]) > 1 and
http_method in self.operations[self.cmd][1]) or
(len(self.operations[self.cmd]) > 2 and
http_method in self.operations[self.cmd][2])
), \
'Unimplemented method ({0}) for command ({1}), which {2} ' \
'an id'.format(http_method,
self.cmd,
'requires' if has_id else 'does not require')
meth = None
if has_id:
meth = self.operations[self.cmd][0][http_method]
elif has_args and http_method in self.operations[self.cmd][1]:
meth = self.operations[self.cmd][1][http_method]
else:
meth = self.operations[self.cmd][2][http_method]
method = getattr(self, meth, None)
if method is None:
return make_json_response(
status=406,
success=0,
errormsg=gettext(
'Unimplemented method ({0}) for this url ({1})').format(
meth, flask.request.path
)
)
return method(*args, **kwargs)
@classmethod
def register_node_view(cls, blueprint):
cls.blueprint = blueprint
id_url, url = cls.get_node_urls()
commands = cls.generate_ops()
for c in commands:
cmd = c['cmd'].replace('.', '-')
if c['with_id']:
blueprint.add_url_rule(
'/{0}{1}'.format(
c['cmd'], id_url if c['req'] else url
),
view_func=cls.as_view(
'{0}{1}'.format(
cmd, '_id' if c['req'] else ''
),
cmd=c['cmd']
),
methods=c['methods']
)
else:
blueprint.add_url_rule(
'/{0}'.format(c['cmd']),
view_func=cls.as_view(
cmd, cmd=c['cmd']
),
methods=c['methods']
)
def children(self, *args, **kwargs):
"""Build a list of treeview nodes from the child nodes."""
children = self.get_children_nodes(*args, **kwargs)
# Return sorted nodes based on label
return make_json_response(
data=sorted(
children, key=lambda c: c['label']
)
)
def get_children_nodes(self, *args, **kwargs):
"""
Returns the list of children nodes for the current nodes. Override this
function for special cases only.
:param args:
:param kwargs: Parameters to generate the correct set of tree node.
:return: List of the children nodes
"""
children = []
for module in self.blueprint.submodules:
children.extend(module.get_nodes(*args, **kwargs))
return children
BaseDriver
class BaseDriver(object):
"""
class BaseDriver(object):
This is a base class for different server types.
Inherit this class to implement different type of database driver
implementation.
(For PostgreSQL/EDB Postgres Advanced Server, we will be using psycopg2)
Abstract Properties:
-------- ----------
* Version (string):
Current version string for the database server
* libpq_version (string):
Current version string for the used libpq library
Abstract Methods:
-------- -------
* get_connection(*args, **kwargs)
- It should return a Connection class object, which may/may not be
connected to the database server.
* release_connection(*args, **kwargs)
- Implement the connection release logic
* gc()
- Implement this function to release the connections assigned in the
session, which has not been pinged from more than the idle timeout
configuration.
"""
@abstractproperty
def version(cls):
pass
@abstractproperty
def libpq_version(cls):
pass
@abstractmethod
def get_connection(self, *args, **kwargs):
pass
@abstractmethod
def release_connection(self, *args, **kwargs):
pass
@abstractmethod
def gc_timeout(self):
pass
BaseConnection
class BaseConnection(object):
"""
class BaseConnection(object)
It is a base class for database connection. A different connection
drive must implement this to expose abstract methods for this server.
General idea is to create a wrapper around the actual driver
implementation. It will be instantiated by the driver factory
basically. And, they should not be instantiated directly.
Abstract Methods:
-------- -------
* connect(**kwargs)
- Define this method to connect the server using that particular driver
implementation.
* execute_scalar(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns single
datum result.
* execute_async(query, params, formatted_exception_msg)
- Implement this method to execute the given query asynchronously and
returns result.
* execute_void(query, params, formatted_exception_msg)
- Implement this method to execute the given query with no result.
* execute_2darray(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns the result
as a 2 dimensional array.
* execute_dict(query, params, formatted_exception_msg)
- Implement this method to execute the given query and returns the result
as an array of dict (column name -> value) format.
* def async_fetchmany_2darray(records=-1, formatted_exception_msg=False):
- Implement this method to retrieve result of asynchronous connection and
polling with no_result flag set to True.
This returns the result as a 2 dimensional array.
If records is -1 then fetchmany will behave as fetchall.
* connected()
- Implement this method to get the status of the connection. It should
return True for connected, otherwise False
* reset()
- Implement this method to reconnect the database server (if possible)
* transaction_status()
- Implement this method to get the transaction status for this
connection. Range of return values different for each driver type.
* ping()
- Implement this method to ping the server. There are times, a connection
has been lost, but - the connection driver does not know about it. This
can be helpful to figure out the actual reason for query failure.
* _release()
- Implement this method to release the connection object. This should not
be directly called using the connection object itself.
NOTE: Please use BaseDriver.release_connection(...) for releasing the
connection object for better memory management, and connection pool
management.
* _wait(conn)
- Implement this method to wait for asynchronous connection to finish the
execution, hence - it must be a blocking call.
* _wait_timeout(conn, time)
- Implement this method to wait for asynchronous connection with timeout.
This must be a non blocking call.
* poll(formatted_exception_msg, no_result)
- Implement this method to poll the data of query running on asynchronous
connection.
* cancel_transaction(conn_id, did=None)
- Implement this method to cancel the running transaction.
* messages()
- Implement this method to return the list of the messages/notices from
the database server.
* rows_affected()
- Implement this method to get the rows affected by the last command
executed on the server.
"""
ASYNC_OK = 1
ASYNC_READ_TIMEOUT = 2
ASYNC_WRITE_TIMEOUT = 3
ASYNC_NOT_CONNECTED = 4
ASYNC_EXECUTION_ABORTED = 5
ASYNC_TIMEOUT = 0.2
ASYNC_WAIT_TIMEOUT = 2
ASYNC_NOTICE_MAXLENGTH = 100000
@abstractmethod
def connect(self, **kwargs):
pass
@abstractmethod
def execute_scalar(self, query, params=None,
formatted_exception_msg=False):
pass
@abstractmethod
def execute_async(self, query, params=None,
formatted_exception_msg=True):
pass
@abstractmethod
def execute_void(self, query, params=None,
formatted_exception_msg=False):
pass
@abstractmethod
def execute_2darray(self, query, params=None,
formatted_exception_msg=False):
pass
@abstractmethod
def execute_dict(self, query, params=None,
formatted_exception_msg=False):
pass
@abstractmethod
def async_fetchmany_2darray(self, records=-1,
formatted_exception_msg=False):
pass
@abstractmethod
def connected(self):
pass
@abstractmethod
def reset(self):
pass
@abstractmethod
def transaction_status(self):
pass
@abstractmethod
def ping(self):
pass
@abstractmethod
def _release(self):
pass
@abstractmethod
def _wait(self, conn):
pass
@abstractmethod
def _wait_timeout(self, conn, time):
pass
@abstractmethod
def poll(self, formatted_exception_msg=True, no_result=False):
pass
@abstractmethod
def status_message(self):
pass
@abstractmethod
def rows_affected(self):
pass
@abstractmethod
def cancel_transaction(self, conn_id, did=None):
pass
|
__label__pos
| 0.992396 |
Commit 16774180 authored by Andreas Mueller's avatar Andreas Mueller Committed by GitHub
fix collocation score computation on 2.7, remove words with empty cou… (#184)
* fix collocation score computation on 2.7, remove words with empty counts.
* copy dict keys on python3
parent bceab74a
......@@ -36,13 +36,15 @@ Namespaces are one honking great idea -- let's do more of those!
def test_collocations():
wc = WordCloud(collocations=False)
wc = WordCloud(collocations=False, stopwords=[])
wc.generate(THIS)
wc2 = WordCloud(collocations=True)
wc2 = WordCloud(collocations=True, stopwords=[])
wc2.generate(THIS)
assert_greater(len(wc2.words_), len(wc.words_))
assert_in("is better", wc2.words_)
assert_not_in("is better", wc.words_)
assert_not_in("way may", wc2.words_)
def test_plurals_numbers():
......
from __future__ import division
from itertools import tee
from operator import itemgetter
from collections import defaultdict
......@@ -54,10 +55,18 @@ def unigrams_and_bigrams(words, normalize_plurals=True):
word2 = standard_form[bigram[1].lower()]
if score(count, counts[word1], counts[word2], n_words) > 30:
# bigram is a collocation
# discount words in unigrams dict. hack because one word might
# appear in multiple collocations at the same time
# (leading to negative counts)
counts_unigrams[word1] -= counts_bigrams[bigram_string]
counts_unigrams[word2] -= counts_bigrams[bigram_string]
# add joined bigram into unigrams
counts_unigrams[bigram_string] = counts_bigrams[bigram_string]
counts_unigrams[bigram_string] = counts_bigrams[bigram_string]
words = list(counts_unigrams.keys())
for word in words:
# remove empty / negative counts
if counts_unigrams[word] <= 0:
del counts_unigrams[word]
return counts_unigrams
......
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|
__label__pos
| 0.983007 |
Home iPhone How to turn on the LED notification light on your iPhone?
How to turn on the LED notification light on your iPhone?
172
0
By activating the LED Flash for Alerts bulunan feature on the iPhone, you can make the flash blink when the phone rings or when a notification is received. Although the flash light for notifications is actually for the visually impaired, it is very useful for many people. For iOS 13 and later, we will explain in detail how to use the flash light as a notification light.
After the iOS 13 update, the Accessibility menu was removed from the General tab and became a stand-alone menu. The LED Flash feature for alerts is also carried under a different menu. In this article, we will illustrate how to turn on the flash on the iPhone and iPad models using iOS 13 and above, when the phone rings or when the notification arrives.
How to turn on the LED notification light on your iPhone?
1. Open the Settings section.
2. Select Accessibility.
3. Select Audio / Visual.
4. Activate the LED Flash option for alerts. This will cause the backlight to blink when the phone rings or when you receive a notification.
5. If you select Blink When Quiet in the same menu, the flash will also flash when your phone is silent.
Using the flash light as a notification light will often not miss calls and notifications. It also adds visual elegance.
If you are having problems with the flash when the iPhone is playing, you can ask us in the comments section.
LEAVE A REPLY
Please enter your comment!
Please enter your name here
|
__label__pos
| 0.988337 |
Running Bitbucket Server as a Linux service
This page describes how to run Bitbucket Server as a Linux service, and only applies if you are manually installing or upgrading Bitbucket Server from an archive file. See the page Install Bitbucket Server from an archive file for more details.
Bitbucket Server assumes that the external database is available when it starts; these approaches do not support service dependencies, and the startup scripts will not wait for the external database to become available.
For production use on a Linux server, Bitbucket Server should be configured to run as a Linux service, that is, as a daemon process. This has the following advantages:
• Bitbucket Server can be automatically restarted when the operating system restarts.
• Bitbucket Server can be automatically restarted if it stops for some reason.
• Bitbucket Server is less likely to be accidentally shut down, as can happen if the terminal Bitbucket Server was manually started in is closed.
• Logs from the Bitbucket Server JVM can be properly managed by the service.
System administration tasks are not supported by Atlassian. These instructions are only provided as a guide and may not be up to date with the latest version of your operating system.
Using the Java Service Wrapper
Bitbucket Server can be run as a service on Linux using the Java Service Wrapper. The Service Wrapper is known to work with Debian, Ubuntu, and Red Hat.
The Service Wrapper provides the following benefits:
• Allows Bitbucket Server, which is a Java application, to be run as a service.
• No need for a user to be logged on to the system at all times, or for a command prompt to be open and running on the desktop to be able to run Bitbucket Server.
• The ability to run Bitbucket Server in the background as a service, for improved convenience, system performance and security.
• Bitbucket Server is launched automatically on system startup and does not require that a user be logged in.
• Users are not able to stop, start, or otherwise tamper with Bitbucket Server unless they are an administrator.
• Can provide advanced failover, error recovery, and analysis features to make sure that Bitbucket Server has the maximum possible uptime.
Please see http://wrapper.tanukisoftware.com/doc/english/launch-nix.html for wrapper installation and configuration instructions.
The service wrapper supports the standard commands for SysV init scripts, so it should work if you just create a symlink to it from /etc/init.d.
Using an init.d script
The usual way on Linux to ensure that a process restarts at system restart is to use an init.d script. This approach does not restart Bitbucket Server if it stops by itself.
1. Stop Bitbucket Server.
2. Create a bitbucket user, set the permissions to that user, create a home directory for Bitbucket Server and create a symlink to make upgrades easier:
$> curl -OL https://www.atlassian.com/software/stash/downloads/binary/atlassian-bitbucket-X.Y.Z.tar.gz
$> tar xz -C /opt -f atlassian-bitbucket-X.Y.Z.tar.gz
$> ln -s /opt/atlassian-bitbucket-X.Y.Z /opt/atlassian-bitbucket-latest
# Create a home directory
$> mkdir /opt/bitbucket-home
# ! Update permissions and ownership accordingly
(Be sure to replace X.Y.Z in the above commands with the version number of Bitbucket Server.)
3. Create the startup script in /etc/init.d/bitbucket with the following contents (Ensure the script is executable by running chmod 755 bitbucket):
#! /bin/sh
### BEGIN INIT INFO
# Provides: bitbucket
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Initscript for Atlassian Bitbucket Server
# Description: Automatically start Atlassian Bitbucket Server when the system starts up.
# Provide commands for manually starting and stopping Bitbucket Server.
### END INIT INFO
# Adapt the following lines to your configuration
# RUNUSER: The user to run Bitbucket Server as.
RUNUSER=vagrant
# BITBUCKET_INSTALLDIR: The path to the Bitbucket Server installation directory
BITBUCKET_INSTALLDIR="/opt/atlassian-bitbucket-X.Y.Z"
# BITBUCKET_HOME: Path to the Bitbucket home directory
BITBUCKET_HOME="/opt/bitbucket-home"
# ==================================================================================
# ==================================================================================
# ==================================================================================
# PATH should only include /usr/* if it runs after the mountnfs.sh script
PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Atlassian Bitbucket Server"
NAME=bitbucket
PIDFILE=$BITBUCKET_HOME/log/bitbucket.pid
SCRIPTNAME=/etc/init.d/$NAME
# Read configuration variable file if it is present
[ -r /etc/default/$NAME ] && . /etc/default/$NAME
# Define LSB log_* functions.
# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
. /lib/lsb/init-functions
run_with_home() {
if [ "$RUNUSER" != "$USER" ]; then
su - "$RUNUSER" -c "export BITBUCKET_HOME=${BITBUCKET_HOME};${BITBUCKET_INSTALLDIR}/bin/$1"
else
export BITBUCKET_HOME=${BITBUCKET_HOME};${BITBUCKET_INSTALLDIR}/bin/$1
fi
}
#
# Function that starts the daemon/service
#
do_start()
{
run_with_home start-bitbucket.sh
}
#
# Function that stops the daemon/service
#
do_stop()
{
if [ -e $PIDFILE ]; then
run_with_home stop-bitbucket.sh
else
log_failure_msg "$NAME is not running."
fi
}
case "$1" in
start)
[ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
do_start
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
stop)
[ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
do_stop
case "$?" in
0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
esac
;;
status)
if [ ! -e $PIDFILE ]; then
log_failure_msg "$NAME is not running."
return 1
fi
status_of_proc -p $PIDFILE "" $NAME && exit 0 || exit $?
;;
restart|force-reload)
#
# If the "reload" option is implemented then remove the
# 'force-reload' alias
#
log_daemon_msg "Restarting $DESC" "$NAME"
do_stop
case "$?" in
0|1)
do_start
case "$?" in
0) log_end_msg 0 ;;
1) log_end_msg 1 ;; # Old process is still running
*) log_end_msg 1 ;; # Failed to start
esac
;;
*)
# Failed to stop
log_end_msg 1
;;
esac
;;
*)
echo "Usage: $SCRIPTNAME {start|stop|status|restart|force-reload}" >&2
exit 3
;;
esac
Running on system boot
1. To start on system boot, add the script to the start up process.
For Ubuntu (and other Debian derivatives) use:
update-rc.d bitbucket defaults
For RHEL (and derivates) use:
chkconfig --add bitbucket --level 0356
Note: You may have to install the redhat-lsb package on RHEL (or derivatives) to provide the LSB functions used in the script.
2. Verify that the Bitbucket Server service comes back up after restarting the machine.
Using a systemd unit file
Thanks to Patrick Nelson for calling out this approach, which he set up for a Fedora system. It also works on other distributions that use systemd as the init system. This approach does not restart Bitbucket Server if it stops by itself.
1. Create a bitbucket.service file in your /etc/systemd/system/ directory with the following lines:
[Unit]
Description=Atlassian Bitbucket Server Service
After=syslog.target network.target
[Service]
Type=forking
User=atlbitbucket
ExecStart=/opt/atlassian-bitbucket-X.Y.Z/bin/start-bitbucket.sh
ExecStop=/opt/atlassian-bitbucket-X.Y.Z/bin/stop-bitbucket.sh
[Install]
WantedBy=multi-user.target
The value for User should be adjusted to match the user that Bitbucket Server runs as. ExecStart and ExecStop should be adjusted to match the path to your <Bitbucket Server installation directory>.
2. Enable the service to start at boot time by running the following in a terminal:
systemctl enable bitbucket.service
3. Stop Bitbucket Server, then restart the system, to check that Bitbucket Server starts as expected.
4. Use the following commands to manage the service:
Disable the service:
systemctl disable bitbucket.service
Check that the service is set to start at boot time:
if [ -f /etc/systemd/system/*.wants/bitbucket.service ]; then echo "On"; else echo "Off"; fi
Manually start and stop the service:
systemctl start bitbucket
systemctl stop bitbucket
Check the status of Bitbucket Server:
systemctl status bitbucket
Last modified on Apr 8, 2019
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|
__label__pos
| 0.713275 |
Common Garlic Toad
from Wikipedia, the free encyclopedia
Common Garlic Toad
Common spadefoot toad (Pelobates fuscus)
Common spadefoot toad ( Pelobates fuscus )
Systematics
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Superfamily : Toad frogs (Pelobatoidea)
Family : Pelobatidae
Genre : European sea toads ( pelobates )
Type : Common Garlic Toad
Scientific name
Pelobates fuscus
( Laurenti , 1768)
The common spadefoot toad ( Pelobates fuscus ) is a frog and belongs to the genus of European sea-toed toads ( Pelobates ) within the superfamily of toad frogs . With the sharp-edged, horny growths on the soles of their feet, they can very quickly bury themselves in loose soil where they spend the day. Due to its hidden way of life and its scattered distribution, the species is generally little known. In order to draw attention to its endangerment in nature, it was named " Lurch of the Year " 2007.
features
Adult males reach a maximum body length of 6.5 cm, females a maximum of around 8 cm; on average, however, both sexes remain somewhat smaller. The color of the common toad varies depending on its lifestyle, regional occurrence and gender. Usually the animals show irregular dark brown, often elongated, island spots on the upper side on a light gray to beige-brown ground. Almost every animal can be individually distinguished. There can also be reddish or brown warts, and red spots on the flanks. Females are usually more reddish-brown in color, while males tend to have gray or clay-yellow tones. In addition, the latter have thickened humerus glands during the mating season. Some copies are almost completely missing the markings. During the stay in the water, many animals darken and thus have a temporarily poorer contrast pattern.
Male with typical "cat's eye"
The belly is whitish in color, often with light to dark gray speckles. Occasionally, albinotic forms also occur. Further distinctive exterior features a helmet-like "apex bump" on the back of the head as well as the vertical slit-shaped pupil as otherwise only under the Central European anurans midwife toad has. The heel hump ( callus internus ) on the soles of the feet of all frogs is particularly enlarged, sharp-edged and hardened in the common garlic toad. It serves the animal as a "grave shovel" (grave callus; compare way of life).
Ventral side; note also the heel bumps on the soles of the feet.
This characteristic - as well as the pupil shape - is shared by the species with its close southern European relatives, the razor foot ( Pelobates cultripes ) and the Syrian red toad ( Pelobates syriacus ), but also with the American red toad (Scaphiopodidae). The color of the grave calluses varies depending on the species - in the common garlic toad they are light brown in color.
The eponymous garlic smell , which is said to be associated with this frog, is only noticeable when there is a strong startle reaction. The secretion given off serves to defend against the enemy. The repertoire of behavior in defending against enemies should also include actively attacking and biting the opponent as well as uttering a startle cry that is similar to a toddler's cry. However, passive behaviors such as inflating the body or crouching down can be observed much more regularly in threatening situations.
Reproduction and Individual Development
( The following phenological data generally refer to the Central European lowlands.)
Garlic toad spawning cord
Size comparison between the larva of a common toad and a common toad larva, which has already been developed further (below). The eyes, which are far out, the breathing hole (spiraculum) on the left flank and the semi-transparent silhouette that can often be observed are clearly visible.
Very light-colored larva of the common spadefoot toad in the stage of metamorphosis
With the arrival of significantly frost-free, rainy nights (mostly around the end of March), spadefoot toads set off from their winter quarters to the breeding waters. They appear here in normal years with winter weather until February / March in often only a few days delayed from typical "Frühlaichern" as common toad or frog , with males as some are in most amphibian species on average active earlier than females.
The mating calls of the males - females are also capable of making sounds - are very quiet due to the lack of sound bubbles and are also usually uttered under water. As a result, they are only audible to the observer at close range. They sound like "wock .. wock .. wock" or "klock .. klock .. klock". The main calling and spawning time is between the end of March and mid-May. Triggered by extensive rainfall in the height of summer, a second courtship and spawning phase (secondary spawning season) occasionally takes place. In the case of the amplexus , the female is clasped by the male in the lumbar region - this is typical of the more original species of Mesobatrachia and Archaeobatrachia ("primordial frogs").
The spawn , which is wrapped in a spiral around vertical plant stems, differs from that of the real toads (thin cords) as well as that of the frogs (balls or clumps): They are thick gelatin cords about 40-70 cm long and one and a half to two centimeters in diameter. They contain between 1200 and 3400 brown-black eggs. After four to ten days of embryonic development, the tadpoles hatch. The older stages of development are noticeably large and move like a fish, with a total length of 9 to 12 centimeters - exceptionally also over 20 cm - significantly larger than many other frog larvae. When viewed from above, they have eyes that are noticeably far apart (as is usually the case with Central European species only tadpoles of the tree frog ) and have relatively strong, dark horned beaks. They like to swim just below the surface of the water in warm layers of water, so that they can dive down in a flash when alarmed and hide in the mud. Even when they leave the larval water (end of June and in July, sometimes later), i.e. when the metamorphosis is complete , the animals are comparatively large: at 2 to 3.5 cm, they have shrunk considerably compared to the larval stage, but are still a good double long like most other freshly metamorphosed frogs in Europe. Garlic toads can become sexually mature after a year; however, they usually only take part in the reproductive process in the second year after the metamorphosis .
Habitat, way of life
The adult toads, apart from the spawning season, are ground-dwelling land animals. They particularly prefer landscapes with loose, sandy to sandy-loamy topsoil (for example heaths, inland dunes , grasslands, steppes). Here the animals can quickly dig in with their heel hump "shovels" on their hind feet and the specially adapted leg muscles. According to a study from northwest Germany, the burial depths are only between 1.5 and 8 centimeters during the spawning season, depending on the type of soil and the environment, but probably significantly deeper during the rest of the time (around 10 to 60 cm). The excavated caves are used several times by the animals. If the environmental conditions are optimal, the underground daytime hiding spots are literally expanded into a living cave, with the walls being mechanically stabilized and strengthened by the common garlic toad. In very dry summers, there can occasionally be longer periods of inactivity, during which the toads rarely leave their burrow.
Adult male
As soon as dusk falls, the animals dig their way out of their underground hiding place in order to look for food on the surface. Garlic toads are mainly insectivores. Their diet consists mainly of beetles , field crickets , grasshoppers and smooth caterpillars, but also woodlice , small to medium-sized snails and earthworms . They themselves belong to the prey spectrum of various bird and mammal species. The most important predators are owls such as the tawny owl (for adult toads) and in particular the mallard when devouring spawn and larvae. In addition, herons , storks and birds of prey also appear as predators of tadpoles and adults (see also: red-footed falcon ).
Habitat with a sandy bottom - ideal for garlic toads
Garlic toads have benefited in many ways from agriculture and its tendency towards ever larger arable land (but compare also: endangerment). The more open, worked ground areas with loose grain, the more frequently the animals migrate into these habitats. Garlic toads particularly like to colonize sandy potato and asparagus fields ("potato toad ").
Spawning waters on the western edge of the area in an intensive agricultural landscape (Heimerzheim, Rhein-Sieg-Kreis, NRW)
Small to medium-sized, eutrophic still waters such as ponds and ponds with a minimum depth of around 30 centimeters are preferred as spawning biotopes . They are also happy to colonize so-called secondary biotopes such as gravel, sand or clay pits, but also extensively managed carp pond areas. A bank zone rich in vegetation, for example overgrown with swath cane , cattail or flood turf , meets the needs of the animals. More often, the spawning grounds are located near or even in the middle of cultivated arable land. Toad to hibernate dig up to a meter deep into the ground. Found cavities in the earth, such as mouse holes or mole passages, are preferred as winter quarters and redesigned according to one's own needs. The garlic toads usually avoid topsoils in the fen as well as in the floodplain and floodplain areas - unless the floodplain is interspersed with drifting sand dunes, geest islands or fluvial sand deposits. This is the case, for example, on the middle Elbe , where the species can even be found in very individual places. In optimal habitats, populations of several hundred or even over a thousand toads can sometimes be detected. In general, it can be assumed that the occurrence of the species is not yet fully known due to its hidden, inconspicuous way of life.
distribution
Distribution map according to IUCN data
A female; It is typical for the stain pattern that a longitudinal line is left out in the middle of the back.
The distribution of the nominate form Pelobates fuscus fuscus mainly includes the lowlands of Central and Eastern Europe. The common spadefoot toad is a continental- pontic species. The westernmost occurrences are on the eastern border of France ( Rhine area ) and in the east of the Netherlands , the northernmost in Denmark and Estonia . In the east the area extends to Kazakhstan and in the south to Upper Italy , northern Serbia and Bulgaria . In Switzerland the species is considered to be extinct or at most has an uncertain status today, in Austria it is scattered outside the Alpine region or rarely found in eastern basin locations ( Styria , Upper Austria , Burgenland , Lower Austria , Vienna ).
The main areas of distribution in Germany are mainly in the lowlands of all north-eastern federal states (= north-eastern German lowlands) and in Lower Saxony (especially in the eastern half). In addition, there are certain accumulation of sites in northern Bavaria (especially: Franconian pond landscape) and in the Upper Rhine lowlands of Baden-Württemberg and southern Hesse . Otherwise, occurrences of this species are only found inconsistently in Germany or are completely absent, especially in the low mountain range regions dominated by weathered rocks.
Systematics
The common spadefoot toad and three other closely related species of the European sea-toed toad ( Pelobates ) usually form an independent family Pelobatidae in recent systematic reviews within the historically "medium-wide" development of the frog suborder Mesobatrachia (which some authors do not separate from the Archaeobatrachia ). Previously, the family Pelobatidae was further defined and also included the American paddock toads and the Asiatic toad frogs . Based on comparative DNA examinations, these are now each regarded as separate families and only grouped together taxonomically in the form of the superfamilies of the toad frogs (Pelobatoidea) and the Pelodytoidea (together with the mud divers ) . Other authors understand the families subsumed in Pelobatoidea and Pelodytoidea partly only as subfamilies.
The disjunct common spadefoot toad in the Italian Po Valley - earlier also in the extreme south of Switzerland - were temporarily treated as a separate subspecies Pelobates fuscus insubricus Cornalia, 1873 (Italian common spadefoot). However, this taxonomic status is now being questioned. In the main distribution area, a western and an eastern form of the common toad are also distinguished; some authors even give the eastern species its own category. At least it seems justified to differentiate this as a further subspecies from the nominate form. The eastern subspecies is called Pelobates fuscus vespertinus and occurs eastwards from eastern Ukraine and the European part of Russia.
Fossil evidence
The earliest fossil finds of the common toad in Central Europe date from the Upper Pliocene , about two million years ago. For the Ice Age ( Pleistocene ) there is widespread, but not very frequent evidence, mainly from areas with loess soils . Post-Ice Age warm phases were associated with intensive reforestation - in the case of the “steppe species” of the common garlic toad, this has even led to a decline in the meantime. Fossilized skeletal remains (but also "modern" for example, in Owls gewöllen be) quite well assign the spadefoot, because it has distinctive features in the bone structure. These include hump-like ossification of the skin on the roof of the skull and butterfly-shaped widenings and transverse processes on the lumbar vertebrae .
Hazard and protection
Gravel pit developed close to nature
Garlic toads, like all Central European amphibians, suffer above all from the destruction or impairment of small bodies of water in the cultural landscape through the filling up or entry of garbage and environmental toxins. The flooding of fertilizers also pollutes many bodies of water and contributes to their premature silting up through eutrophication . However, in this respect the common garlic toads seem to be somewhat less sensitive than species such as the tree frog . If people put fish in small bodies of water that would not naturally occur there, this usually leads to a collapse of amphibian populations, as their spawn and larvae are eaten by most fish. In extensive carp pond farms with near-natural reed areas, garlic toads can survive quite well and also build up larger populations. This then sometimes happens to the annoyance of pond owners, who perceive the large tadpoles as a nuisance, perhaps also as a food competitor for their carp. Therefore, the completely harmless tadpoles, which feed on suspended organic matter and occasionally carrion and injured conspecifics, are still being combated.
The settlement of arable land is associated with considerable dangers for the common garlic toads. They can be injured or killed by agricultural machines during tillage, suffer lethal skin burns from artificial fertilizers, be affected when sewage sludge and liquid manure are spread and be poisoned by pesticides directly or indirectly via the food chain . In addition, the spadefoot toad is endangered by road traffic when migrating, for example if a road runs between the winter quarters and the spawning water.
While the populations of the species in area centers (such as in Germany, for example in Brandenburg and Saxony-Anhalt ) are often still assessed as safe, regional tendencies to decline are also noticeable, especially at the margins of distribution. In North Rhine-Westphalia the species is now considered "critically endangered".
Front view of a Common Garlic Toad with its pupils wide open
Legal protection status (selection)
National Red List classifications (selection)
• Red List Federal Republic of Germany: 3 - endangered
• Red list of Austria: EN (corresponds to: highly endangered)
• Red list of Switzerland: DD (data deficient = insufficient data situation)
nomenclature
Outdated scientific synonyms are Bufo fuscus Laurenti, 1768 (first description), Rana fusca Freyhans, 1779 and Bombina marmorata Koch, 1828. Johann Georg Wagler introduced the taxonomically correct scientific name Pelobates fuscus in 1830. This name was derived from the Greek ( ho pelos = mud, bainein = to go) and the Latin ( fuscus = dark brown, dark gray). Little to hardly used German-language trivial names are "garlic toad", "garlic frog toad", "brown toad frog", "land toad", "water toad" or "brown" or "marbled limber". In English the species is called "Common Spadefoot", in French "Pélobate brun", in Dutch "Knoflookpad", in Italian "Pelobate bruno", in Polish "Grzebiuszka ziemna".
Sources and further information
Individual evidence
1. Karen Jahn: Observations on the burial depth of Pelobates fuscus during the spawning season. - Zeitschrift für Feldherpetologie 4 (1997, Issue 1), pp. 165-172. ISBN 3-933066-00-X
2. for example: Viktor Wendland: The garlic toad (Pelobates fuscus) in Berlin and the surrounding area. - Milu, 2, pp. 332-339 (1967).
3. Andreas Nöllert: The garlic toad. - Neue Brehm-Bücherei, Ziemsen-Verlag, Wittenberg, 2nd edition 1990, 103 pages ISBN 3-7403-0243-7 ; there also quotes from further references to this statement.
4. Andreas Krone (ed.): The garlic toad (Pelobates fuscus) - distribution, biology, ecology and protection. RANA, special issue 5, Rangsdorf 2008, ISBN 978-3-9810058-6-8
5. M. García-París, DR Buchholtz & G. Parra-Olea: Phylogenetic relationships of Pelobatoidea re-examined using mtDNA. - Molecular Phylogenetics and Evolution 28 (2003), pp. 12-23.
6. Alain Dubois: Amphibia Mundi. 1.1. An ergotaxonomy of recent amphibians. - Alytes, Intern. Journal of Batrachology, Vol. 23, 2005, pp. 1-24.
7. Kurt Grossenbacher: On the characterization and current situation of the Italian garlic toad, Pelobates fuscus insubricus. P. 17–28 in: Andreas Krone (Ed.): The garlic toad (Pelobates fuscus) - distribution, biology, ecology and protection. RANA, special issue 5, Rangsdorf 2008, ISBN 978-3-9810058-6-8
8. Axel Kwet & Andreas Nöllert: The garlic toad - from Rösel von Rosenhof to the Froschlurch of the year 2007. P. 5–16 in: Andreas Krone (ed.): The garlic toad (Pelobates fuscus) - distribution, biology, ecology and protection. RANA, special issue 5, Rangsdorf 2008, ISBN 978-3-9810058-6-8
9. Gottfried Böhme: On the historical development of the Herpetofaunen of Central Europe in the Ice Age (Quaternary). - In: Rainer Günther (Ed.): The amphibians and reptiles of Germany. - G. Fischer-Verlag, Jena, 1996, pp. 30-39. ISBN 3-437-35016-1
10. Bernd Stöcklein: Investigations on amphibian populations on the edge of the Central Franconian pond landscape with special consideration of the common toad (Pelobates fuscus Laur.). - PhD. at the Univ. Erlangen-Nürnberg, 1980, 192 pp.
11. For example: Christian Fischer: Population and area losses of natterjack toads (Bufo calamita) and garlic toads (Pelobates fuscus) in East Frisia (NW Lower Saxony). - Journal for field herpetology, Laurenti-Verlag, Bochum, vol. 6 (1999), pp. 95-101.
12. Isabella Draber: Protection of the common garlic toad in Münsterland: Investigations on larvae and juveniles of the common garlic toad (Pelobates fuscus) as part of a Life + project in Münstrerland (North Rhine-Westphalia) . Osnabrück University of Applied Sciences, Osnabrück 2015.
13. Garlic toad at www.wisia.de
14. Federal Agency for Nature Conservation (ed.): Red list of endangered animals, plants and fungi in Germany 1: Vertebrates. Landwirtschaftsverlag, Münster 2009, ISBN 978-3-7843-5033-2
15. Online overview at www.amphibienschutz.de
literature
• Andreas Krone (Ed.): The garlic toad (Pelobates fuscus) - distribution, biology, ecology and protection. RANA, special issue 5, Rangsdorf 2008, ISBN 978-3-9810058-6-8 .
• Norbert Menke, Christian Göcking & Arno Geiger: The garlic toad (Pelobates fuscus) - distribution, biology, ecology, protection strategies and breeding. LANUV-Fachberichte 75, 2016, 279 S. full text as pdf
• Robert Mertens: The amphibians and reptiles of the Rhine-Main area. - Verlag Kramer, Frankfurt / M., 1975.
• Burkhard Müller: Bio-acoustic and endocrinological investigations on the common toad Pelobates fuscus fuscus (Laurenti, 1768) (Salientia: Pelobatidae). In: Salamandra. Volume 20, 1984, pp. 121-142.
• Andreas Nöllert: The garlic toad. Neue Brehm-Bücherei, Ziemsen-Verlag, Wittenberg, 2nd edition 1990, 103 pages ISBN 3-7403-0243-7 .
• Andreas Nöllert, Rainer Günther: Garlic Toad - Pelobates fuscus (Laurenti, 1768). In: Rainer Günther (Ed.): The amphibians and reptiles of Germany. G. Fischer-Verlag, Jena / Stuttgart / Lübeck / Ulm 1996, ISBN 3-437-35016-1 , pp. 252-274.
• Peter Sacher: Multi-year observation of a population of the common spadefoot toad (Pelobates fuscus). - Hercynia NF Vol. 24 (1987), pp. 142-152.
• Hans Schneider: The mating calls of native frogs (Discoglossidae, Pelobatidae, Bufonidae, Hylidae). In: Journal for Morphology and Ecology of Animals. Volume 57, 1966, pp. 119-136.
• Hans Schneider: Bioacoustics of the Froschlurche - native and related species. With audio CD. Supplement to the Zeitschrift für Feldherpetologie 6. Laurenti Verlag, Bielefeld 2005. ISBN 3-933066-23-9 . Audio samples 10–11.
• Ulrich Sinsch: Gravel as secondary habitats for threatened amphibians and reptiles. In: Salamandra, Volume 24, Issue 2/3, 1988, pp. 161-174.
Web links
Commons : Common Garlic Toad - Album with pictures, videos and audio files
Wiktionary: Common Garlic Toad - explanations of meanings, origins of words, synonyms, translations
This version was added to the list of articles worth reading on February 8, 2006 .
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The OSI Model: An Essential Foundation to Networking
Updated: Mar 26
No technology that is connected to internet is un-hackable. It's only a matter of time.
Introduction
What is the OSI Model? The OSI, short for (the Open Systems Interconnection model) is a conceptual framework for understanding how network communication works. It was the first standard model adopted by all major computer and telecommunication companies in the early 1980s.
The OSI Model (aka ISO-OSI, i.e., International Organization of Standardization – Open System Interconnection) divides the communication process between two devices into seven layers. It provides a standard reference model that allows different networking technologies and protocols to interoperate and communicate.
Scenario
Imagine you have two servers that need to share information. The message doesn't just magically teleport from an application on the first machine to the application on the other. Instead, it transits down the layers and eventually reaches the transmission line. Once it jumps across the gap to the other device, it has to repeat the process in reverse by ascending layers until it reaches the receiving application.
Core Definition
For any starting number N representing a layer that transmits a message, the OSI model can be used to explain the transmission few key concepts:
• Protocol Data Units (PDUs) are abstracted messages that include payloads, headers, and footers.
• Service Data Units (SDUs) are equivalent to the payloads.
At each subsequent transition from some layer N to some layer N-1, a layer-N PDU becomes a new N-1 SDU. This payload gets wrapped up in a layer N-1 PDU with the relevant headers and footers. On the opposite end, the data passes up the chain, unwrapping at each relevant stage until it's just a payload that the corresponding layer-N device can consume.
The 7 Layers of OSI
7 Layers of the OSI Model
7 Layers of the OSI Model
We'll describe OSI layers "top-down" from the application layer that directly serves the end user to the physical layer.
7. The Application Layer
• The application layer is the highest layer of the OSI Model and is responsible for providing the interface between the network and the end user's application.
• Standard network services such as file transfer, email, and web browsing are provided at the application layer. Protocols such as HTTPS (Hypertext Transfer Protocol Secure) and, FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol) operate at this layer, allowing users to access and transfer files and other resources over the network.
Functions of the Application Layer
Functions of the Application Layer
• The application layer also provides the interface for user authentication and authorization. Protocols such as LDAP (Lightweight Directory Access Protocol) and Kerberos are used to verify the identity of users and grant them access to specific resources or services on the network.
6. The Presentation Layer
• The presentation layer is responsible for formatting and encoding data in a standardized way independent of the application or system being used. It includes protocols like SSL (Secure Sockets Layer) that provide secure communication.
• It deals with issues such as data compression and encryption.
• An example of a presentation service would be converting an extended binary-coded decimal interchange code text computer file to an ASCII-coded file. The presentation layer could translate between multiple data formats using a standard format if necessary.
Functions of the Presentation Layer
Functions of the Presentation Layer
5. The Session Layer
• The session layer establishes, maintains, and terminates connections between devices. Some standard protocols that operate at the session layer include Remote Procedure Call (RPC), NetBIOS (Network Basic Input Output System), and Windows Internet Name Service (WINS).
Functions of the Session Layer
Functions of the Session Layer
Some standard functions of the session layer include :
• Setting up and tearing down communication sessions between devices.
• Synchronizing the flow of data between devices.
• Resuming communication after a temporary interruption or fault.
• Negotiating the options and parameters for a communication session.
• Managing access to shared resources during a communication session.
4. The Transport Layer
• The transport layer provides end-to-end communication services and error recovery for the application layer. It includes protocols like TCP (Transmission Control Protocol) and (UDP) User Datagram Protocol that provides error correction, flow control, and data segmentation and reassembly.
• Every protocol uses a unique decimal number to ensure that the data is sent and received on the intended application as it passes through the network or Internet.
Functions of the Transport Layer
Functions of the Transport Layer
• TCP is a connection-oriented protocol that guarantees the delivery of the message, while UDP is a connectionless protocol that sends the data without error correction. Under the TCP and UDP are port numbers used to distinguish the specific type of application.
3. The Network Layer
• The network layer is responsible for routing data between different networks. It includes protocols like (IP) Internet Protocol, (IPX) Internetwork Packet Exchange, and AppleTalk. These protocols provide the necessary functions for routing data across a network and ensuring it reaches its destination.
• It is responsible for determining the best path for data as it travels from its source to its destination. The network layer also assigns logical addresses to devices on the network, which are used to identify the devices and route data to them.
Functions of the Network Layer
Functions of the Network Layer
• The network layer is often considered the "heart" of the OSI model because it plays a central role in the operation of a network. It is a critical component of modern computer networks and is essential for allowing devices to communicate with each other and exchange information.
2. The Data Link Layer
• The data link layer links two devices on the same physical network, such as a local area network (LAN). It ensures that data is transmitted correctly and without errors.
• It includes protocols like (SDLC) Synchronous Data Link Protocol, (HDLC) High-Level Data Link Protocol, (SLIP)Serial Line Interface Protocol, (PPP)Point - to - Point Protocol, (LCP) Link Control Protocol, and (NCP) Network Control Protocol.
• This layer comprises two parts—Logical Link Control (LLC), which identifies network protocols, performs error checking, and synchronizes frames. Media Access Control (MAC) uses MAC addresses to connect devices and define permissions to transmit and receive data.
Functions of the Data Link Layer
Functions of the Data Link Layer
• Overall, the data link layer is crucial in ensuring data's reliable and efficient transmission over a network.
1. The Physical Layer
• The physical layer is responsible for transmitting raw data over a communication channel, including the hardware, cables, and other components that make up the network.
• It defines the physical characteristics of the communication channel, including the signaling used, the frequency range, and the data rate.
Functions of the Physical Layer
Functions of the Physical Layer
• The physical layer ensures that data is transmitted accurately and reliably from one device to another.
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Lifestyle
• Avoid wearing clothes that are tight around the stomach area
• Sleep on a wedge shaped pillow that's at least 6 to 10 inches thick on one end. Don't substitute regular pillows; they just raise your head, and not your entire upper body.
• Take regular exercise to keep your digestive system working efficiently, reducing the risk of heartburn
• Avoid smoking – chemicals inhaled from cigarette smoke can cause the ring of muscle that separates your oesophagus from your stomach to relax. This can allow stomach acid to leak up into your oesophagus more easily - visit smokefree.nhs.uk for advice to help you stop smoking
Diet
• Eat small meals regularly throughout the day instead of three large meals
• Avoid eating less than three hours before bedtime
• Eat slowly
• Avoid or keep fatty or spicy food to a minimum
• Avoid or keep coffee, alcohol, acidic fruit juices and vinegar consumption to a minimum
• Try to identify triggers that make your heartburn worse. Then remove them from your diet to see whether avoiding specific foods helps your symptoms to improve
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I'm trying to emulate the behavior of this drag n drop found here
How do I change the following code to get the mouse over effect with the rectangle outline? Also is it possible to have it sortable like the example above?
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<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.9/jquery-ui.min.js"></script>
<script>
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$("#draggable li")
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if (diffClick < clickDelay) {
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revertDuration: 10,
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containment: '.demo',
start: function(e, ui) {
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$("#droppable, #draggable").droppable({
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hoverClass: "ui-state-active",
drop: function(e, ui) {
$('.' + selectedClass).appendTo($(this)).add(ui.draggable)
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</script>
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</div>
</body>
</html>
share|improve this question
I heartily recommend using jqueryui.com/demos/droppable instead. – Blazemonger Oct 25 '11 at 14:49
I am using this but I'm trying to emulate the outlined rectangle for the drop zone from the page linked. – Paul Oct 25 '11 at 14:59
you should be able to reproduce that in jQuery droppable with an activeClass and some CSS. – Blazemonger Oct 25 '11 at 15:00
up vote 2 down vote accepted
The link you posted has an example created without jQuery, and I have done the same several times myself with a slightly different approach.
I'm sure there is an easier way in jQuery UI draggable, and the documentation would be the first place to look.
However, to show how it's done in regular javacript without a library, wich should probably work with jQuery as well, as it uses regular event listeners, you would do something like this:
var dropzone;
dropzone = document.getElementById("dropzone");
dropzone.addEventListener("dragenter", dragin, false);
dropzone.addEventListener("dragleave", dragout, false);
dropzone.addEventListener("drop", drop, false);
This binds the events to functions, that would look something like this:
function drop(e) {
//do something when dropped
e.stopprop, preventdefault etc.
}
function dragin(e) {
//do something when dragged in
e.stop stuff
}
function dragout(e) {
//do something when dragged out, usually remove the stuff you did above
e.stop stuff
}
This is the way it's normally done, and just as mouseenter and mouseleave, the drag event listeners should work with jQuery, and you could probably use .bind(); to bind them to some sort of action in exactly the same way as the mouse events, allthough I have never tested this as I always do this without jQuery.
share|improve this answer
I would have 2 classes. One with how the div looks normally, then another with how it should look when something is dragged over it (over, out). Then for the event handlers, I would toggle the classes.
Here is some sample code that will change the color of a div from silver to red as something is dragged over it:
<style>
.selectedCategory {
width: 200px;
height: 35px;
background: silver;
}
.selectedCategoryActive {
width: 200px;
height: 35px;
background: red;
}
</style>
<div id="element" class="selectedCategory"></div>
$('#element').droppable({
over: function(event, ui) {
$(this).toggleClass('selectedCategoryActive');
},
out: function(event, ui) {
$(this).toggleClass('selectedCategoryActive');
}
});
share|improve this answer
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__label__pos
| 0.935423 |
Orbit
Sentinel-3 Mission Orbit
The Sentinel-3 orbit is similar to the orbit of Envisat allowing continuation of the ERS/Envisat time series.
Sentinel-3 uses a high inclination orbit (98.65°) for optimal coverage of ice and snow parameters in high latitudes. The orbit inclination is the angular distance of the orbital plane from the equator.
The Sentinel-3 orbit is a near-polar, sun-synchronous orbit with a descending node equatorial crossing at 10:00 h Mean Local Solar time. In a sun-synchronous orbit, the surface is always illuminated at the same sun angle.
The orbital cycle is 27 days (14+7/27 orbits per day, 385 orbits per cycle). The orbit cycle is the time taken for the satellite to pass over the same geographical point on the ground.
The two in-orbit Sentinel-3 satellites enable a short revisit time of less than two days for OLCI and less than one day for SLSTR at the equator.
The orbit reference altitude is 814.5 km.
Sentinel-3B's orbit is identical to Sentinel-3A's orbit but flies +/-140° out of phase with Sentinel-3A.
The following table contains a summary of useful orbital information for Sentinel-3:
Altitude
Inclination
Period
Cycle
Ground-track deviation
Local Time at Descending Node
814.5 km
98.65 deg
100.99 min
27 days
+- 1 km
10:00 hours
The KML data files displaying the Sentinel-3 orbit ground tracks for a complete cycle with a time step of 10 seconds are available below:
Download ASCII files with the Sentinel-3 reference latitude and longitude, for a complete cycle, with a time step of 1 second.
|
__label__pos
| 0.604742 |
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Patents
Publication numberUS5940294 A
Publication typeGrant
Application number08/631,458
Publication date17 Aug 1999
Filing date12 Apr 1996
Priority date
12 Apr 1996
Inventors
Original Assignee
U.S. Classification
International Classification
Cooperative Classification
European Classification
G05B19/042P
References
External Links
System for assisting configuring a process control environment
US 5940294 A
Abstract
A configuration assistant system is disclosed which guides a user through configuring a process control environment via a sequence of screen presentations. The configuration assistant system advantageously enables a process control designer or user to quickly and easily configure a process control environment. The screen presentations may be contained within a plurality of instructional sections to further assist the process control designer in configuring the process control environment.
Claims
What is claimed is:
1. A method for configuring a process control environment, the process control environment including a computer system having a processor coupled to a display device, the method comprising:
providing a plurality of instructional sections, the instructional sections setting forth information relating to configuring a process control environment;
presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections;
guiding a user through the configuration of the process control environment via a question and answer session conducted via the sequence of configuration screen presentations, and
configuring the system based upon responses from the user to the question and answer session.
2. The method of claim 1 wherein the plurality of instructional sections include an introduction instructional section, the introduction instructional section providing the user with introductory information relating to the configuration of the process control environment.
3. The method of claim 1 wherein the plurality of instructional sections include a controller instructional section, the controller instructional section providing a sequence of screen presentations for guiding the user through the process of configuring controllers within the process control environment.
4. The method of claim 1 wherein the plurality of instructional sections include a controller hierarchy instructional section, the controller hierarchy section providing a sequence of screen presentations for guiding the user through the process of configuring a controller hierarchy within the process control environment.
5. The method of claim 1 wherein the plurality of instructional sections include a workstation instructional section, the workstation instructional section providing a sequence of screen presentations for guiding the user through the process of configuring a workstation within the process control environment.
6. The method of claim 1 wherein the instructional sections are implemented using an object oriented framework.
7. The method of claim 6 wherein the object oriented framework includes classes; and
the instructional sections include classes derived from a set of commercially available foundation classes.
8. The method of claim 1 wherein the configuration of the process control environment is stored within a database, the database including information relating to the process control environment; and
the database is continuously updated as the user is guided through the configuration process.
9. The method of claim 1 wherein the configuration of the process control environment is reflected within an explorer portion of the process control environment.
10. The method of claim 1 wherein the sequence of screen presentations has an order, the order being determined by the question and answer session.
11. The method of claim 1 wherein the guiding the user includes presenting, on the display device, a configuration screen presentation including a textual question, wherein an answer to the question provided by the user determines which of the sequence of configuration screen presentations is presented next on the display device.
12. A system for configuring a process control environment, the system comprising:
a computer including a process coupled to a memory and a display device coupled to the processor;
a plurality of instructional sections stored in the memory, the instructional sections setting forth information relating to configuring the process control environment;
means for presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections;
means for guiding a user through the configuration of the process control environment via a question and answer session conducted via the sequence of configuration screen presentations, and
means for configuring the system based upon responses from the user to the question and answer session.
13. The system of claim 12 wherein the plurality of instructional sections include an introduction instructional section, the introduction instructional section providing the user with introductory information relating to the configuration of the process control environment.
14. The system of claim 12 wherein the plurality of instructional sections include a controller instructional section, the controller instructional section providing a sequence of screen presentations for guiding the user through the process of configuring controllers within the process control environment.
15. The system of claim 12 wherein the plurality of instructional sections include a controller hierarchy instructional section, the controller hierarchy section providing a sequence of screen presentations for guiding the user through the process of configuring a controller hierarchy within the process control environment.
16. The system of claim 12 wherein the plurality of instructional sections include a workstation instructional section, the workstation instructional section providing a sequence of screen presentations for guiding the user through the process of configuring a workstation within the process control environment.
17. The system of claim 12 wherein the instructional sections are implemented in software.
18. The system of claim 17 wherein the software is implemented using an object oriented framework.
19. The system of claim 18 wherein the object oriented technology includes classes; and
the instructional sections include classes derived from a set of commercially available foundation classes.
20. The system of claim 12 further comprising:
a database including information relating to the process control environment;
and wherein the database is continuously updated as the user is guided through the configuration process.
21. The system of claim 12 further comprising:
an explorer portion coupled to the processor; and
wherein the configuration of the process control environment is reflected within the explorer portion of the process control environment.
22. The system of claim 12 wherein the sequence of screen presentations has an order, the order being determined by the question and answer session.
23. The method of claim 12 wherein the means for guiding the user includes means for presenting, on the display device, a configuration screen presentation including a textual question, wherein an answer to the question provided by the user determines which of the sequence of configuration screen presentations is presented next on the display device.
24. An article of manufacture comprising:
a non-volatile memory;
a plurality of instructional sections stored in the non-volatile memory, the instructional section setting forth information relating to configuring a process control environment;
means for presenting, on a display device, a sequence of configuration screen presentations relating to the instruction sections, the means for presenting being stored in the non-volatile memory;
means for guiding a user through the configuration of the process control environment via a question and answer session conducted via the sequence of configuration screen presentations, the means for guiding being stored in the non-volatile memory, and
means for configuring the system based upon responses from the user to the question and answer session, the means for configuring being stored in the non-volatile memory.
25. The article of claim 24 wherein the sequence of screen presentations has an order, the order being determined by the question and answer session.
26. The method of claim 24 wherein the means for guiding the user includes means for presenting, on the display device, a configuration screen presentation including a textual question, wherein an answer to the question provided by the user determines which of the sequence of configuration screen presentations is presented next on the display device.
27. A method of configuring a process control environment, the process control environment including a computer system having a processor coupled to a display device, the method comprising:
providing a plurality of instructional sections, the instructional sections setting forth information relating to configuring a process control environment;
presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sequence;
guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations;
gathering information to configure the process control environment via a user dialog conducted via the sequence of screen presentations, and
configuring the system based upon responses from the user to the question and answer session.
28. A method for configuring a process control environment, the process control environment including a computer system having a processor coupled to a display device, the method comprising:
providing an object oriented framework, the object oriented framework including classes from a set of commercially available foundation classes and classes derived from a set of commercially available foundation classes;
providing a plurality of instructional sections, the providing the plurality of instructional sections including using at least one instructional section class derived from the set of commercially available foundation classes, the at least one instructional section class including information relating to configuring a process control environment;
presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections, the presenting including using at least one configuration screen presentation class derived from the set of commercially available foundation classes;
guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations, and
configuring the system based upon responses from the user to the question and answer session.
29. The method of claim 28 wherein the plurality of instructional sections include an introduction instructional section, the introduction instructional section providing the user with introductory information relating to the configuration of the process control environment, the providing the introduction instructional section including using an introduction instructional section class.
30. The method of claim 28 wherein the plurality of instructional sections include a controller instructional section, the controller instructional section providing a sequence of screen presentations for guiding the user through the process of configuring controllers within the process control environment, the providing the controller instructional section including using a controller instructional section class.
31. The method of claim 28 wherein the plurality of instructional sections include a controller hierarchy instructional section, the controller hierarchy section providing a sequence of screen presentations for guiding the user through the process of configuring a controller hierarchy within the process control environment, the providing the controller hierarchy instructional section including using a controller hierarchy instructional section class.
32. The method of claim 28 wherein the plurality of instructional sections include a workstation instructional section, the workstation instructional section providing a sequence of screen presentations for guiding the user through the process of configuring a workstation within the process control environment, the providing the workstation instructional section including using a workstation instructional section class.
33. The method of claim 28 wherein the guiding the user through the configuration of the process control environment includes guiding the user via a question and answer session conducted via the sequence of configuration screen presentations.
34. The method of claim 28 wherein the configuration of the process control environment is stored within a database, the database including information relating to the process control environment; and
the database is continuously updated as the user is guided through the configuration process.
35. The method of claim 28 wherein the configuration of the process control environment is reflected within an explorer portion of the process control environment.
36. The method of claim 28 wherein the at least one configuration screen presentation class is a dialog class.
37. A system for configuring a process control environment, the system comprising:
a computer system including a processor coupled to a memory and a display device coupled to the processor;
an object oriented framework stored in the memory, the object oriented framework including classes from a set of commercially available foundation classes and classes derived from the set of commercially available foundation classes, the object oriented framework including a plurality of instructional section classes derived from the set of commercially available foundation classes, the instructional section classes including information for providing a plurality of instructional sections setting forth information relating to configuring the process control environment;
means for presenting, on the display device, a sequence of configuration screen presentations relating to the instructional sections, the means for presenting using at least one configuration screen presentation class derived from the set of commercially available foundation classes;
means for guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations, and
means for configuring the system based upon responses from the user to the question and answer session.
38. The system of claim 37 wherein the plurality of instructional section classes include an introduction instructional section class, the introduction instructional section class including information for providing an introduction instructional section, the introduction instructional section providing the user with introductory information relating to the configuration of the process control environment.
39. The system of claim 37 wherein the plurality of instructional section classes include a controller instructional section class, the controller instructional section class including information for providing a controller instructional section, the controller instructional section providing a sequence of screen presentations for guiding the user through the process of configuring controllers within the process control environment.
40. The system of claim 37 wherein the plurality of instructional section classes include a controller hierarchy instructional section class, the controller hierarchy section class including information for providing a controller hierarchy section, the controller hierarchy section providing a sequence of screen presentations for guiding the user through the process of configuring a controller hierarchy within the process control environment.
41. The system of claim 37 wherein the plurality of instructional section classes include a workstation instructional section class, the workstation instructional section class including information for providing a workstation instructional section, the workstation instructional section providing a sequence of screen presentations for guiding the user through the process of configuring a workstation within the process control environment.
42. The system of claim 37 wherein the instructional sections are implemented in software.
43. The system of claim 37 further comprising:
a database including information relating to the process control environment; and
wherein the database is continuously updated as the user is guided through the configuration process.
44. The system of claim 37 further comprising:
an explorer portion coupled to the processor; and
wherein the configuration of the process control environment is reflected within the explorer portion of the process control environment.
45. The system of claim 37 wherein the means for guiding the user through the configuration of the process control environment includes means for guiding the user via a question and answer session conducted via the sequence of configuration screen presentations.
46. The method of claim 37 wherein the at least one configuration screen presentation class is a dialog class.
Description
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A process control environment 100 is shown in FIG. 1 and illustrates a control environment for implementing a digital control system, process controller or the like. The process control environment 100 includes an operator workstation 102 and an engineering workstation 106 electrically interconnected by a local area network ("LAN") 108, or other known communication link, for transferring and receiving data and control signals among the various workstations and a plurality of controller/multiplexers 110. Workstations 102 and 106 are, for example, computers which conform to the IBM compatible architecture. The workstations 102 and 106 are shown connected by the LAN 108 to a plurality of the controller/multiplexers 110 that electrically interface between the workstations and a plurality of processes 112. In multiple various embodiments, the LAN 108 includes a single workstation connected directly to a controller/multiplexer 110 or alternatively includes a plurality of workstations, for example two workstations 102 and 106, and many controller/multiplexers 110 depending upon the purposes and requirements of the process control environment 100. In some embodiments, a single process controller/multiplexer 110 controls several different processes 112 or alternatively controls a portion of a single process.
In the process control environment 100, a process control strategy is developed by creating a software control solution on the engineering workstation 106, for example, and transferring the solution via the LAN 108 to the operator workstation 102, lab workstation 104, and to controller/multiplexer 110 for execution. The operator workstation 102 supplies interface displays to the control/monitor strategy implemented in the controller/multiplexer 110 and communicates to one or more of the controller/multiplexers 110 to view the processes 112 and change control attribute values according to the requirements of the designed solution. The processes 112 are formed from one or more field devices, which may be smart field devices or conventional (non-smart) field devices.
In addition, the operator workstation 102 communicates visual and audio feedback to the operator regarding the status and conditions of the controlled processes 112. The engineering workstation 106 includes a processor 116, and a display 115 and one or more input/output or user-interface device 118 such as a keyboard, light pen and the like. The workstation 106 also includes a memory 117, which includes both volatile and non-volatile memory. The operator workstation 102 and other workstations (not shown) within the process control environment 100 include at least one central processing unit (not shown) which is electrically connected to a display (not shown) and a user-interface device (not shown) to allow interaction between a user and the processor.
The memory 117 includes a control program that executes on the processor 116 to implement control operations and functions of the process control environment 100. The memory 117 also includes a configuration assistant system 130 which is stored within the non-volatile memory when the configuration assistant system 130 is not in operation. The control program also includes an explorer portion which assists a user in navigating throughout the process control environment 100. The explorer portion of the control program is discussed in more detail in the application to Nixon et al. entitled "A Process Control System for Versatile Control of Multiple Process Devices of Various Device Types" having attorney docket number M-3923, which application is hereby incorporated by reference.
Configuration assistant system 130 assists a user in the process of creating a process configuration for a process control environment. Configuration assistant system 130 is designed to be understandable by a user who has no previous experience in configuring a process control environment. At a broad level, configuration assistant system 130 gathers information via a question and answer session which is conducted via a sequence of screen presentations which are presented on display 115 of, e.g., engineering workstation 102 and continuously writes this information to a database (not shown). The information in the database may then be directly downloaded to a controller 110 to configure the controller 110. In addition to writing the configuration information to the database, the configuration information obtained from the user during the operation of the configuration assistant system 130 is used to update the explorer portion of the control program.
Referring to FIG. 2, a schematic block diagram illustrates a hierarchical relationship among system objects of a configuration model 200. The configuration model 200 includes many configuration aspects including control, I/O, process graphics, process equipment, alarms, history and events. The configuration model 200 also includes a device description and network topology layout.
The configuration model hierarchy 200 is defined for usage by a particular set of users for visualizing system object relationships and locations and for communicating or navigating maintenance information among various system objects. For example, one configuration model hierarchy 200, specifically a physical plant hierarchy, is defined for usage by maintenance engineers and technicians for visualizing physical plant relationships and locations and for communicating or navigating maintenance information among various instruments and equipment in a physical plant. An embodiment of a configuration model hierarchy 200 that forms a physical plant hierarchy supports a subset of the SP88 physical equipment standard hierarchy and includes a configuration model site 210, one or more physical plant areas 220, equipment modules 230 and control modules 240.
The configuration model hierarchy 200 is defined for a single process site 210 which is divided into one or more named physical plant areas 220 that are defined within the configuration model hierarchy 200. The physical plant areas 220 optionally contain tagged modules, each of which is uniquely instantiated within the configuration model hierarchy 200. A physical plant area 220 optionally contains one or more equipment modules 230. An equipment module 230 optionally and hierarchically contains other equipment modules 230, control modules 240 and function blocks. An equipment module 230 includes and is controlled by a control template that is created according to one of a number of different graphical process control programming languages including continuous function block, ladder logic, or sequential function charting ("SFC"). The configuration model hierarchy 200 optionally contains one or more control modules 240. A control module 240 is contained in an object such as a physical plant area 220, an equipment module 230 or another control module 240. A control module 240 optionally contains objects such as other control modules 240 or function blocks.
User Interface Aspects of Configuration Assistant System
Referring to FIGS. 3A and 3B, each screen presentation generated by configuration assistant system 130 includes a navigation portion 302 as well as a screen specific portion 304. The navigation portion 302 includes navigation tabs 310 which allow a user to access particular sections of the configuration assistant system 300. For example, when configuration assistant 300 is first accessed, start navigation tab 312 is actuated. Additional navigation tabs include controller navigation tab 314, controller hierarchy navigation tab 316, workstation navigation tab 318, install navigation tab 320 and end navigation tab 321 which provide access to the controller section, controller hierarchy section, workstation section, install and the end section of configuration assistant system 130, respectively.
The navigation portion 302 also includes a variety of buttons which provide navigation functions. More specifically, navigation portion 302 includes Back button 330, Next button 332, Help button 334 and Navigate button 336. The Back button 332 takes the user to the previous screen presentation in strict historical order. The Next button 334 takes the user to the screen presentation appropriate for the selections that are made on the current screen presentation. The help button 334 accesses the help contents for the configuration assistant system. The navigate button 336 brings up a list of screen presentations already viewed. When configuration assistant system 130 is accessed, it first takes default values of the process control environment 100 where they are sufficient to get the system running. If the elements of the environment 100 are not in auto internet protocol (IP) address assignment mode, then the environment is set to the auto IP address assignment mode and the user is notified.
The layout of the screen specific portion 304 of each screen presentation conforms to one of four general layout categories: informational screen layout, Choice screen layout, Selection screen layout and Data Entry screen Layout.
More specifically, referring to FIG. 4A, information screen layout 400 includes a picture portion 402 as well as a descriptive text portion 404. The picture portion 402 includes a bit mapped picture which is context specific. This picture orients a user to the context of the function that the user is performing and also improves the appearance of the screen presentation. The descriptive text portion 404 provides a textual explanation to step a user through the configuration assistant system 130. FIG. 4B shows an example of an information screen presentation.
Referring to FIG. 5A, choice screen layout 500 includes a picture portion 502, a descriptive text portion 504 and a radio button portion 506. The picture portion 502 and descriptive text portion 504 perform the same function as in the information screen layout. The radio button portion 506 set forth radio button that may be actuated to chose a particular selection. FIG. 5B shows an example of a choice screen presentation.
Referring to FIG. 6A, select screen presentation 600 includes picture portion 602, descriptive text portion 604 and list selection portion 606. The picture portion 602 and descriptive text portion 604 perform the same function as in the information screen layout and choice screen layout. The list selection portion 606 provides a list of choices from which a user may select one or more choices. FIG. 6B shows an example of a select screen presentation.
Referring to FIG. 7A, Data Entry screen presentation 700 includes picture portion 702 and descriptive text portion 704 as well as an information entry portion 706. The information entry portion 706 includes fields such as name field 708 and description field 710 into which information is entered by a user. The picture portion 702 and descriptive text portion 704 perform the same function as in the information screen layout, choice screen layout and select screen layout. FIG. 7B shows an example of a Data Entry screen presentation.
Implementation of Configuration Assistant System
The process control environment 100 and more specifically configuration assistant system 130 is implemented using an object-oriented framework. An object-oriented framework uses object-oriented concepts such as class hierarchies, object states and object behavior. These concepts, which are briefly discussed below, are well known in the art. The preferred object-oriented framework is written using object-oriented programming languages, such as the C++ programming language, which is well-known in the art.
The building block of an object-oriented framework is an object. An object is defined by a state and a behavior. The state of an object is set forth by fields of the object. The behavior of an object is set forth by methods of the object. Each object is an instance of a class, which provides a template for the object. A class defines zero or more fields and zero or more methods.
Fields are data structures which contain information defining a portion of the state of an object. Objects which are instances of the same class have the same fields. However, the particular information contained within the fields of the objects can vary from object to object. Each field can contain information that is direct, such as an integer value, or indirect, such as a reference to another object.
A method is a collection of computer instructions which can be executed in processor 116 by computer system software. The instructions of a method are executed, i.e., the method is performed, when software requests that the object for which the method is defined perform the method. A method can be performed by any object that is a member of the class that includes the method. The particular object performing the method is the responder or the responding object. When performing the method, the responder consumes one or more arguments, i.e., input data, and produces zero or one result, i.e., an object returned as output data. The methods for a particular object define the behavior of that object.
Classes of an object-oriented framework are organized in a class hierarchy. In a class hierarchy, a class inherits the fields and methods which are defined by the superclasses of that class. Additionally, the fields and methods defined by a class are inherited by any subclasses of the class. Ie., an instance of a subclass includes the fields defined by the superclass and can perform the methods defined by the superclass. Accordingly, when a method of an object is called, the method that is accessed may be defined in the class of which the object is a member or in any one of the superclasses of the class of which the object is a member. When a method of an object is called, process control environment 100 selects the method to run by examining the class of the object and, if necessary, any superclasses of the object.
A subclass may override or supersede a method definition which is inherited from a superclass to enhance or change the behavior of the subclass. However, a subclass may not supersede the signature of the method. The signature of a method includes the method's identifier, the number and type of arguments, whether a result is returned, and, if so, the type of the result. The subclass supersedes an inherited method definition by redefining the computer instructions which are carried out in performance of the method.
Classes which are capable of having instances are concrete classes. Classes which cannot have instances are abstract classes. Abstract classes may define fields and methods which are inherited by subclasses of the abstract classes. The subclasses of an abstract class may be other abstract classes; however, ultimately, within the class hierarchy, the subclasses are concrete classes.
All classes defined in the disclosed preferred embodiment, except for mix-in classes which are described below, are subclasses of a class, CObject. Thus, each class that is described herein and which is not a mix-in class inherits the methods and fields of class CObject.
More specifically, configuration assistant system 130 is implemented using the Foundation classes version 4.0 of the Microsoft developers kit for Visual C++ for Windows NT version 3.51. Specifically, the dialog classes descend from the CDialog class of the Foundation classes, the section classes descend from the CObject classes of the Foundation classes. Configuration assistant system 130 also includes Class CHcaApp (not shown) which descends from the foundation class CWinApp (not shown) and relates to the windowing features of the configuration assistant system.
Referring to FIG. 8, the class hierarchy for the instructional section classes which descend from class CObject 800 class are shown. More specifically, class CHcaSection 802 descends from the Foundation class CObject 800. Class CHcaSection 802 is a virtual base class which controls which screen to present to the user at a given time.
Section classes ClntroSection 810, CCtrlrSection 812, CEndSection 814, CWkstnSection 816, CInstlSection 818 and CSP88Section 820 descend from class CHcaSection 802. Class CCtrlrSection 812 controls presentation of the controller section and determines which screen is presented at a given time. Class CEndSection 814 controls presentation of the end section and determines which screen is presented at a given time. Class CWkstnSection 816 controls the workstation section and determines which screen to present at a given time. Class CInstlSection 818 controls the install section and determines which screen presentation should be presented at a given time. ClntroSection 819 controls the introduction section and determines which screen presentation to present at a given time. Class CSP88Section 820 controls the control hierarchy section and determines which screen presentation to present at a given time.
Referring to FIGS. 9A-9D, the class hierarchy for the dialog classes which descend from class CDialog 900 are shown. The class CHawkDialog 902 descends from class CDialog 900. The class CHcaDialogBase 904 descends from class CHawkDialog 902. Class CHcaDlg 903 also descends from class CHawkDialog 902 and is associated with class CHcaDialogBase 904.
Class CHcaDlg 903 is the parent dialog for all the screens in the configuration assistant system 130. Class CHcaDlg 903 presents the screens presentations using class CHcaSection 802 based helper classes and controls the tabs 312-320 for accessing the sections as well as the next button 332, back button 330, help button 334, and navigate button 336. Class CHcaDialogBaseD 904 is a base class for controlling the nested dialogs in the configuration assistant system 130.
A plurality of configuration assistant system dialog classes descend from class CHcaDialogBase 904. These configuration assistant system dialog classes are generally grouped into a plurality of generalizations which are generally related to the various instructional sections. One class which descends from class CHcadialogBase 904 and is not within one of the generalization groups is class CNaviagateD 905. Class CNavigateD 905 presents a list of screen presentations in historical order so that the user can access a previously viewed screen presentation.
More specifically, referring to FIG. 9A, configuration assistant system dialog classes which are within the introduction, install and end generalization and which descend from class CHcaDialogBase 904 include classes CIntro1D 910, Clntro2D 911, CIntro3D 912, CInstlAnotherD 913, CInstlCheckD 914, ClnstlCheckOrInstfD 915, CInstlCtrlrSelectD 916, CinstlMaindD 917, CInstlStard) 918, ClnstlStatusD 919, CInstlWkstnSelectD 920 and CEndStart 921.
More specifically, Class CIntro1D 910 presents the first page of the introduction section. Class CIntro2D 911 presents the second page of the introduction section. Class CIntro3D 912 presents the third page of the introduction section. Class CInstlAnotherD 913 asks whether the user wishes to install another node in the system. Cass CMsWlCheckD 914 presents the results of checking the database to see if everything that is required to run the configuration assistant system 130 is stored within the database and presents any problems found to the user. Class CInstlCheckD 914 also presents a "fix it" button (not shown) which transfers the user to the screen presentation most likely to fix the problem. Class CInstCheckOrInstID 915 asks whether the user wishes to check the configuration that has been generated by the configuration assistant system 130 before installing it, or whether the configuration should be installed without being checked. Class CInstlCtrlSelectD 916 presents a list of controllers to the user and asks which one to install. Class ClnstIMainD 917 presents the main screen presentation for the install section; the main screen presentation for the install section presents the starting choices for installing the system. Class CInstdStart) 918 is the start screen presentation for the install section; this start screen presentation introduces what will be done in this section. Class CInstlStatusD 919 presents the status of the install process as it is occurring. Class CInstlWkstnSelectD 920 presents a list of workstations to the user and asks which workstation the user wishes to install. Class CEndStartD 921 presents the start screen for the end section; this screen presentation congratulates the user and tells the user that the process of configuring the system is complete.
Referring to FIG. 9B, configuration assistant system dialog classes which are within the workstation generalization and which descend from class CHcaDialogBase 904 include CWkstnAnotherNetD 930, CWkstnAnotherOperD 931, CWksnAnotherPCD 932, CWkstnCreateDiskD 933, CWkstnDiskPathD 934, CWkstnMainD 935, CWkstnNetStartD 936, CWkstnOperateD 937, CWkstnPCsD 938, CWkstnPropsD 939 and CWkstnStartD 940.
More specifically, Class CWkstnAnotherNetD 930 asks whether the user wants to add a personal computer (PC), i.e., a workstation, modify a PC, or if the user is done editing PCs. Class CWkstnAnotherOperD 931 asks whether the user wishes to configure the operating capabilities of another PC. Class CWkstnAnotherPCD 932 asks whether the user wishes to configure another PC. Class CWkstnCreateDiskD 933 asks whether the user wishes to create a configuration diskette. Class CWkstnDiskPathD 934 allows the user to enter the path to the configuration file. Class CWkstnMainD 935 presents the main screen for the workstation section; the main screen provides the starting choices for configuring workstations. Class CWkstnPropsD 939 allows the user to enter the properties of the workstation. Class CWkstNetStartD 936 asks whether the user wishes to add a PC or modify a PC. Class CWkOperateD 937 presents a list of areas and asks the user to select which areas can be operated from the present PC. Class CWkstnPCsD 938 presents a list of PCs and asks the user which one the user wishes to configure. Class CWkstnStartD 940 is the start screen for the workstation section; the start screen for the workstation section introduces what will be done in this section.
Referring to FIG. 9C, configuration assistant system dialog classes which are within the controller generalization and which descend from class CHcaDialogBase 904 include CCtrlrStartD 950, CCtrlrMaindD 951, CCtrlrAssignD 952, CCtrlrAnotherCardOrCtrlrD 953, CCtrlrAnotherChannelD 954, CCtrlrAnotherSlotD 955, CCtrlrCardTypesD 956, CCtrlrChannelsD 957, CCtrlrCharPropsD 958, CCtrlrPropsD 959, CCtrlrSelectD 960 and CCtrlrSlotsD 961.
Class CCtrlrStartD 950 presents the start screen presentation for the controller section; this screen presentation introduces what functions will be accomplished in the controller section. Class CCtrlrMainD 951 presents the main screen presentation for the controller section; the main screen presentation presents the staring choices for configuring controllers 110. Class CCtrlrAssignD 952 presents a list of auto-sensed controllers 110 to allow the user to select one of the controllers 110 to be configured. Class CtrlrAnotherCardOrCtrl 953 asks whether the user wishes to configure another card on the present controller or another controller. Class CCtrlAnotherChannel 954 asks whether the user wishes to configure another channel on the present card. Class CCtrlrAnotherSlotD 955 asks whether the user wishes to configure another slot in the present controller. Class CCtrlrCardTypesD 956 presents a list of card types to allow the user to select the type of card present in a slot. Class CCtrhrChannelsD 957 presents a list of channels or ports for a given card and allows the user to select one of the channels or ports to set the properties thereof. Class CCtrlrChanPropsD 958 allows the user to enter the properties of a given channel or port of a card. Class CCtriPropaD 959 allows the user to enter the properties of a controller, these properties include name and description. Class CCtrlrSelectD 960 allows the user to select a controller from a list for purposes of configuring the controller 110. Class CCtrlrSlotsD 961 presents a list of slots in a controller to allow the user to configure the card types present in the slots.
Referring to FIG. 9D, configuration assistant system dialog classes which are within the controller hierarchy generalization and which descend from class CHcaDialogBase 904 include CSP88AlgoTypeD 970, CSP88AnotherAreaD 971, CSP88AreaPropsD 972, CSP88AreaSelectD 973, CSP88AttributesD 974, CSP88DisplaysD 975, DSP88EditAreaD 976, SCP88EditModuleD 977, CSP88EditOtherD 978, CSP88EditWhatD 979, CSP88MaindD 980, CSP88ModKindD 981 CSP88ModePathD 982, CSPModPropsD 983, CSP88ModSelectD 984, CSP88NodeAssignmentD 985,CSP88PeriodD 986, CSP88Stara) 987 and CSP88StartromD 988.
More specifically, Class CSP88AIgoTypeD 970 queries the user regarding the work type algorithm to use in the module being created. Class CSP88AnotherAreaD 971 queries the user whether the user wishes to configure another area or configure the modules in the present area. Class CSP88AreaPropsD 972 allows the user to enter the properties of an area including the name and description of the area. Class CSP88AreaSelectD 973 allows the user to select an area to be modified. Class CSP88AttributesD 974 presents a list of attributes for a module and allows the user to edit the attributes using a standard attribute editing dialog. Class CSP88DisplaysD 975 allows the user to enter the primary, detail and instrument displays associated with a module. Class CSP88EditAreaD 976 asks whether the user wishes to add or rename an area. Class CSP88EditModuleD 977 asks whether the user wishes to add a module or modify a module. Class CSP88EditOtherD 978 asks whether the user wishes to configure another part of the present module, configure another module, or configure another area. Class CSP88EditWhatD 979 asks whether the user wishes to configure the properties of a module or the attributes. Class CSP88MainD 980 presents the main screen for the control hierarchy section; the main screen for the control hierarchy section presents the starting choices for editing the control hierarchy. Class CSP88ModPathD 982 allows the user to enter a path to a module from which the module presently being created will be derived. Class CSP88ModPropsD 983 allows the user to enter the properties of a module. Class CSP88ModSelectD 984 presents a list of modules from which list the user may select one. Class CSP88NodeAssignment 985 asks the user for the name of the node to which the present module will be assigned. Class CSP88PeriodD 986 allows the user to enter the execution period and priority of a module. Class CSP88StartD 987 presents start screen for the control hierarchy section; the start screen for the control hierarchy section introduces the section. Class CSP88StartFromD 988 asks whether the user wants to create a module from scratch or from another module.
Operation of Configuration Assistant System
Referring generally to FIGS. 10-14, the operation of configuration assistant system 130 is conceptually performed on a section by section basis. The access to a particular instructional section is controlled by the section class hierarchy portion of configuration assistant system 130. Specifically, FIG. 10 shows the operation of the instructional section, FIG. 11 shows the operation of the controller section, FIG. 12 shows the operation of the controller hierarchy section, FIG. 13 shows the operation of the workstation section, and FIG. 14 shows the operation of the install section.
More specifically, when configuration assistant system 130 is first accessed, a starting screen conforming to the start section of the configuration assistant system is displayed. This screen presentation conforms to the information layout. From this screen, a user may select another tab, 312-320, or the Next button 332. When another tab is selected, the next screen to be displayed is the starting screen for the selected tab. Alternately, when the Next button 332 is actuated, the next screen to be displayed is the starting screen for the Controllers section. The class which presents the dialog for the initial screen presentations is the CHcaDlg class.
Other alternatives from any screen presentation, including the starting screen presentation, include actuation of the Navigate button 336 and actuation of the tour button 338. When the navigate button is actuated, a navigate dialog screen presentation is presented. The users may then select a screen presentation from the list of screen presentations available. The configuration assistant system 130 then presents the selected screen presentation. The class which presents the dialog for the navigate dialog screen presentation is the CHcaDlg class.
The configuration assistant system includes a plurality of user edit node modes of operation. These user edit node modes of operation include moving a controller node from auto-sensed to configured and adding a controller node to the environment.
When moving a controller node from auto-sensed to configured, the user selects the controller tab 314 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a controller main choice screen presentation to be presented; the controller main choice screen presentation conforms to the Choice screen layout. The choices presented include: assign an existing controller; add a controller placeholder; configure a controller's properties; and, configure a controllers I/O. The user then actuates the assign existing controller radio button and actuates the Next button 332. The configuration assistant system 130 then presents a controller assignment select screen presentation which conforms to the Choice screen layout and provides a list of auto-sensed controllers. The user then selects a controller from the list of auto-sensed controllers and actuates the next button 332. The configuration assistant system 130 then presents a controller properties data entry screen presentation which conforms to the Data Entry screen layout. The user then enters the controller properties including the Name and Description of the controller. If the user is not sure to which controller 110 he is referring, then the user actuates a flash button (not shown). Actuating the flash button causes the configuration assistant system 130 to cause the selected controller 110 to flash a light. The user then merely looks at the controllers of the environment 100 to determine which controller 110 has a blinking light. Actuating the flash button (not shown) also causes a light to flash within the picture of the controller, thus indicating to a user that the controller's actual light is flashing. Once the controller properties have been entered, then the next button is actuated, thus causing configuration assistant system 130 to present the controller main choice screen presentation. The classes which present the dialog for this function are CCtrlrMainD, CCtrlrAssignD, and CCtrlrPropsD.
When adding a controller node place holder to the environment, the user selects the controller tab 314 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the controller main choice screen presentation to be presented. The user then actuates the add controller placeholder radio button and actuates the Next button 332. The configuration assistant system 130 then presents a controller properties data entry screen presentation which conforms to the Data Entry screen layout. The user then enters the controller properties including the Name and Description of the controller. Once the controller properties have been entered, then the next button is actuated, thus causing configuration assistant system 130 to present the controller main choice screen presentation. The classes which present the dialog for this function are CCtrlrMainD and CCtrlrPropsD.
The configuration assistant system 130 includes a plurality of user edit cards of a node modes of operation. These user edit cards of a node modes of operation include setting the properties of an auto-sensed card and adding a card to a node.
When setting the properties of an auto-sensed card, the user selects the controller tab 3l4 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the controller main choice screen presentation to be presented. The user then actuates the configure controller I/O radio button and actuates the Next button 332. The configuration assistant system 130 then presents a controllers select screen presentation which conforms to the Choice screen layout and provides a list of configured controllers. The user then selects a controller from the list of configured controllers and actuates the next button 332. The configuration assistant system 130 then presents a slots select screen presentation which conforms to the Choice screen layout and provides a list of slots in the selected controller. The user then selects a slot with a card in it from the list of slots and actuates the next button 332. The configuration assistant system 130 then presents a channel properties data entry screen presentation which conforms to the Data Entry screen layout. The user then enters the channel properties including the channel type, the enabled/disabled status and the I/O tag of the card and actuates the next button 332. The configuration assistant system 130 then causes a continue choice screen presentation to be presented. The continue choice screen presentation asks the user whether he wishes to configure another channel. If the user selects yes, then the configure card select screen presentation is again presented. If the user select no, then the user is asked whether he wishes to configure another card on this controller or another controller or is done configuring controllers. If the user selects another card then the controller slots select screen presentation is presented. If the user selects another controller, then the controllers select screen presentation is presented. If the user select done with controllers, then the control hierarchy tab section of the configuration assistant system 130 is initiated. The classes which present the dialog for this function are CCtrlrMaind, CCtrlrSelectD, CCtrlrSlotsD, CCtrlrCardD, CChannelPropsD, CAnothehrCardOrChannelD, and CAnotherControllerD.
When adding a card to a node, the user selects the controller tab 314 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the controller main choice screen presentation to be presented. The user then actuates the configure controller I/O radio button and actuates the Next button 332. The configuration assistant system 130 then presents a controllers select screen presentation which conforms to the Choice screen layout and provides a list of configured controllers. The user then selects a controller from the list of configured controllers and actuates the next button 332. The configuration assistant system 130 then presents a slots select screen presentation which conforms to the Choice screen layout and provides a list of slots in the selected controller. The user then selects an empty slot from the list of slots, selects a configure slot radio button and actuates the next button 332. The configuration assistant system 130 then presents a configure slot screen presentation which conforms to the Choice screen layout and provides a list of card types. The user then selects a card type from the list of card types and actuates the next button 332. The configuration assistant system 130 then causes a continue choice screen preston to be presented. The continue choice screen presentation asks the user whether he wishes to configure another slot. If the user selects yes, then the controller slots select screen presentation is again presented. If the user select no, then the user is asked whether he wishes to configure another controller or is done configuring controllers. If the user selects another controller, then the controllers select screen presentation is presented. If the user select done with controllers, then the control hierarchy section of the configuration assistant system 130 is initiated. The classes which present the dialog for this function are CCtrlrMaind, CCtrlrSelectD, CCtrlrSlotsD, CCtrlrCardD, and CAnotherControllerD.
The configuration assistant system 130 includes a plurality of user edit areas modes of operation. These user edit areas modes of operation include adding an area and renaming an area.
When adding an area, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a control hierarchy main choice screen presentation to be presented; the control hierarchy main choice screen presentation conforms to the Choice screen layout. The control hierarchy main choice screen choices include edit an area and edit the modules in an area. The user then actuates the edit an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents a areas choice select screen presentation which conforms to the Choice screen layout and provides the options of add an area or rename an area. The user then selects the add an area choice and actuates the next button 332. The configuration assistant system 130 then presents an area properties data entry screen presentation which conforms to the Data Entry screen layout. The user then enters the area properties including the Name and Description of the area. Once the area properties have been entered, then the next button is actuated. The configuration assistant system 130 then presents a choice screen presentation. The choices are configure modules for this area, configure another area and done configuring areas. The user select the done configuring areas choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditAreaD, CSP88AreaPropsD and CSP88AnotherAreaD.
When renaming an area, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a control hierarchy main choice screen presentation to be presented; the control hierarchy main choice screen presentation conforms to the Choice screen layout. The control hierarchy main choice screen choices include edit an area and edit the modules in an area. The user then actuates the edit an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents a areas choice select screen presentation which conforms to the Choice screen layout and provides the options of add an area or rename an area. The user then selects the rename an area choice and actuates the next button 332. The configuration assistant system 130 then presents an area properties data entry screen presentation which conforms to the Data Entry screen layout and includes an area name in the name field. The user then enters a new name in the name field of the area properties. Once the name has been entered, then the next button is actuated. The configuration assistant system 130 then presents a choice screen presentation. The choices are configure modules for this area, configure another area and done configuring areas. The user select the done configuring areas choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditAreaD, CSP88AresPropsD and CSP88AnotherAreaD.
The configuration assistant system 130 includes a plurality of user edit modules modes of operation. These user edit modules modes of operation include adding a module to an area, editing the properties of a module and editing the attributes of a module and editing a module.
When adding a module to an area, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the control hierarchy main choice screen presentation to be presented The user then actuates the edit the modules in an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents an areas select screen presentation which conforms to the Select screen layout and provides a list of areas. The user then selects an area and actuates the next button 332. The configuration assistant system 130 then causes a module choice screen presentation to be presented; the choices presented are add a new module and modify a module. For adding a module, the user then actuates the add a new modules radio button and actuates the Next button 332. The configuration assistant system 130 then presents a series of data entry screen presentations conform to the Data Entry screen layout. The user then enters properties including the Name and Description of the module, create from scratch or from a library module and function block or SFC algorithm. After the data has been entered, a choice screen is presented asking whether the user wishes to configure the module, modify a different module in this area or done configuring modules in this area. The user selects the done configuring modules choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditModuleD, CSP88ModPropsD, CSP88StartFromD and CSP88AlgoTypeD.
When editing the properties of a module, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the control hierarchy main choice screen presentation to be presented The user then actuates the edit the modules in an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents an areas select screen presentation which conforms to the Select screen layout and provides a list of areas. The user then selects an area and actuates the next button 332. The configuration assistant system 130 then causes a module choice screen presentation to be presented; the choices presented are add a new module and modify a module. For editing the properties of a module, the user then actuates the modify a modules radio button and actuates the Next button 332. The configuration assistant system 130 then presents a select screen which lists the modules for the current area. The user then selects the module to be edited and actuates the next button 332. The configuration assistant system 130 then presents a choice screen presentation, the choices are edit the properties or edit the configuration view. For editing the properties of a module, the user actuates the edit the properties radio button and actuates the Next button 332. The configuration assistant system 130 then presents a series of data entry screen presentations conforming to the Data Entry screen layout. The user then enters properties including the Node assignment, execution period and priority, and primary, detail and instrument displays. After the data has been entered, a choice screen is presented asking whether the user wishes to configure the attributes of the module, configure another module in this area, configure another area or done configuring modules in this area. The user selects the done configuring modules choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditModuleD, CSP88EditOtherD, CSP88NodeAssigmentD, CSP88PeriodD and CSP88DisplaysD.
When editing the attributes of a module, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the control hierarchy main choice screen presentation to be presented. The user then actuates the edit the modules in an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents an areas select screen presentation which conforms to the Select screen layout and provides a list of areas. The user then selects an area and actuates the next button 332. The configuration assistant system 130 then causes a module choice screen presentation to be presented; the choices presented are add a new module and modify a module. For editing the attributes of a module, the user then actuates the modify a modules radio button and actuates the Next button 332. The configuration assistant system 130 then presents a select screen which lists the modules for the current area. The user then selects the module to be edited and actuates the next button 332. The configuration assistant system 130 the presents a choice screen presentation, the choices are edit the properties or edit the configuration view. For editing the attributes of a module, the user actuates the edit the configuration view radio button and actuates the Next button 332. The configuration assistant system 130 then presents an attributes select screen presentation. The user selects an attribute and actuates an edit attribute button (not shown). An attribute properties dialog is presented thus allowing the user to edit the attribute. After the data has been entered, a choice screen is presented asking whether the user wishes to configure the attributes of the module, configure another module in this area, configure another area or done configuring modules in this area. The user selects the done configuring modules choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditModuleD, CSP88EditOtherD, CSP88Attributes.
When editing a module, the user selects the control hierarchy tab 316 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes the control hierarchy main choice screen presentation to be presented. The user then actuates the edit the modules in an area radio button and actuates the Next button 332. The configuration assistant system 130 then presents an areas select screen presentation which conforms to the Select screen layout and provides a list of areas. The user then selects an area and actuates the next button 332. The configuration assistant system 130 then causes a module choice screen presentation to be presented; the choices presented are add a new module and modify a module. For editing a module, the user then actuates the modify a modules radio button and actuates the Next button 332. The configuration assistant system 130 then presents a select screen which lists the modules for the current area. The user then selects the module to be edited and actuates the next button 332. The configuration assistant system 130 the presents a choice screen presentation, the choices are edit the properties or edit the configuration view. For editing a module, the user actuates a edit algorithm button (see FIG. 3B). The configuration assistant system 130 then causes a Control Studio system to be executed. The Control Studio system is discussed in more detail in cofiled application entitled in the application to Dove et al. entitled "System for Configuring a Process Control Environment" having attorney docket number M-3927, which application is hereby incorporated by reference in its entirety. After the module has been edited, control returns from the control studio system and a choice screen is presented asking whether the user wishes to configure the attributes of the module, configure another module in this area, configure another area or done configuring modules in this area. The user selects the done configuring modules choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CSP88MainD, CSP88EditModuleD and CSP88EditOtherD.
The configuration assistant system 130 includes a plurality of user edit workstations modes of operation. These user edit workstation modes of operation include adding a workstation node to the system, modifying a workstation node in the system, creating a configuration diskette and configuring the operating capabilities of the workstation.
When adding a workstation node to the system, the user selects the workstation tab 318 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are configure network properties and configure operating capabilities. The user then actuates the configure network properties radio button and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are add a workstation, modify a workstation, and create a configuration diskette. The user then actuates add a workstation radio button and actuates the Next button 332. The configuration assistant system 130 then presents the workstation properties data entry screen The user then enters properties including the Name and Description of the workstation and actuates the Next button 332. After the data has been entered, a choice screen is presented asking whether the user wishes to add a workstation, modify a workstation or is done adding and modifying workstations in the system. The user selects the done adding and modifying choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CWkstnStartD, CWkstnMainD, CWkstnNetworkD, CWkstnPropsd, and CWks therD.
When modifying a workstation node in the system, the user selects the workstation tab 318 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are configure network properties and configure operating capabilities. The user then actuates the configure network properties radio button and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are add a workstation, modify a workstation, and create a configuration diskette. The user then actuates modify a workstation radio button and actuates the Next button 332. The configuration assistant system 130 then presents the workstation select screen which lists the workstations in the system. The user then selects the workstation to be modified and actuates the next button 332. The configuration assistant system 130 then presents the workstation properties data entry screen. The user then enters properties including the Name and Description of the workstation and actuates the Next button 332. After the data has been entered, a choice screen is presented asking whether the user wishes to add a workstation, modify a workstation or is done adding and modifying workstations in the system. The user selects the done adding and modifying choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CWkstnStartD, CWkstnMainD, CWkstnNetworkD, CWkstnSelectD, CWkstnPropsD, and CWksAnotherD.
When creating a configuration diskette, the user selects the workstation tab 318 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are configure network properties and configure operating capabilities. The user then actuates the configure network properties radio button and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are add a workstation, modify a workstation, and create a configuration diskette. The user then actuates create a configuration diskette radio button and actuates the Next button 332. The configuration assistant system 130 then presents the configuration diskette data entry screen. The user then enters a path to the configuration diskette and actuates the Next button 332. After the data has been entered, the configuration file is written to the path, and a choice screen is presented asking whether the user wishes to add or modify a workstation or define the operational capabilities of workstations in the system. The classes which present the dialog for this function are CWkstnStartD, CWkstnMainD, CWkstnNetworkD, CWkstnDiskD, and CWkstnAnotherD.
When configuring the operating capabilities of a workstation, the user selects the workstation tab 318 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are configure network properties and configure operating capabilities. The user then actuates the configure operating capabilities radio button and actuates the Next button 332. The configuration assistant system 130 then causes the workstation select screen to appear. The user then selects a workstation and actuates the next button 332. The configuration assistant system 130 then causes the operate areas select screen presentation to be presented, which lists all areas available from which to operate. The user then selects the areas from which the selected workstation can operate from the list of all areas and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choice presented is whether the user wishes to configure another workstation. The user then selects no and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices are whether the user wishes to add or modify another PC, i.e., workstation or define the operational capabilities of PC's. Control then transitions to the next section. The classes which present the dialog for this function are CWkstnStartD, CWkstnMainD, CWkostiNetworkD, CWkstnDiskD, and CWkstnAnotherD.
The configuration assistant system 130 includes a single user installation mode of operation. When installing a controller on the system, the user selects the install tab 320 from the main screen presentation and actuates the next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are install the system, install a workstation and install a controller. The user then actuates the install a controller radio button and actuates the Next button 332. The configuration assistant system 130 then causes a controller select screen presentation to be presented. The user then selects a controller, and actuates the Next button 332. The configuration assistant system 130 then causes a choice screen presentation to be presented. The choices presented are check the configuration and go ahead and install the controller. The user then actuates the check the configuration radio button and actuates the Next button 332. The configuration assistant system 130 then initiates a series of checks to verify nothing is missing. For each check that fails, and informational screen which describes the problem is displayed. Included in the screen is a fix it button. If the user selects the fixit button, the configuration assistant system 130 will display the screen most likely to fix the problem, if the information requested by the screen is correctly entered by the user. After presenting the informational check screens, the configuration assistant system 130 automatically installs the configuration and presents an install status screen. After the installation is complete the configuration assistant system 130 causes a choice screen presentation to be presented. The choices presented are install another node and done with installation. The user selects the done installing choice and actuates the next button thus causing the configuration assistant system 130 to present the control hierarchy main choice screen presentation. The classes which present the dialog for this function are CInstlStartD, ClnstlMainD, ClnstlCheckOrInstID, CInstlCheckD, CInstlStatusD, and CInstlAnotherD.
Other Embodiments
Other embodiments are within the following claims.
More specifically, while particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention, including but not limited to implementations in other programming languages. Additionally, while the preferred embodiment is disclosed as a software implementation, it will be appreciated that hardware implementations such as application specific integrated circuit implementations are also within the scope of the following claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
FIG. 1 is a schematic block diagram showing a workstation in accordance with a generalized embodiment of the present invention.
FIG. 2 is a schematic block diagram showing a hierarchical relationship among system objects of a configuration model in accordance with an embodiment of the present invention.
FIG. 3A is a block diagram of the screen presentation of the configuration assistant system in accordance with the present invention.
FIG. 3B is an example of a screen presentation of the configuration assistant system.
FIG. 4A is a block diagram of a screen presentation of the Information screen presentation of the configuration assistant system in accordance with the present invention.
FIG. 4B is an example of an Information screen presentation.
FIG. 5A is a block diagram of a screen presentation of a choice screen presentation of the configuration assistant system in accordance with the present invention.
FIG. 5B is an example of a choice screen presentation.
FIG. 6A is a block diagram of a screen presentation of a Selection screen presentation of the configuration assistant system in accordance with the present invention.
FIG. 6B is an example of a Selection screen presentation.
FIG. 7A is a block diagram of a screen presentation of a Data Entry screen presentation of the configuration assistant system in accordance with the present invention.
FIG. 7B is an example of a Data Entry screen presentation.
FIG. 8 is a block diagram showing the class hierarchy of the configuration assistant system classes that descend from class CObject.
FIGS. 9A-9D are block diagrams showing the class hierarchy of the configuration assistant classes that descend from class CDialog.
FIG. 10 is a flow chart showing the operation of the introduction section of the configuration assistant system.
FIGS. 11A-11C are flow charts showing the operation of the controller section of the configuration assistant system.
FIGS. 12A-12D are flow charts showing the operation of the controller hierarchy section of the configuration assistant system.
FIGS. 13A-13C are flow charts showing the operation of the workstation section of the configuration assistant system.
FIG. 14 is a flow chart showing the operations of the install section of the configuration assistance system.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to process monitoring and control systems. More specifically, the present invention relates to a system for assisting configuring a process monitoring and control system.
2. Description of the Related Art
Present-day process control systems use instruments, control devices and communication systems to monitor and manipulate control elements, such as valves and switches, to maintain at selected target values one or more process variables, including temperature, pressure, flow and the like. The process variables are selected and controlled to achieve a desired process objective, such as attaining the safe and efficient operation of machines and equipment utilized in the process. Process control systems have widespread application in the automation of industrial processes such as the processes used in chemical, petroleum, and manufacturing industries, for example.
Control of the process is often implemented using microprocessor-based controllers, computers or workstations which monitor the process by sending and receiving commands and data to hardware devices to control either a particular aspect of the process or the entire process as a whole. The specific process control functions that are implemented by software programs in these microprocessors, computers or workstations may be individually designed, modified or changed through programming while requiring no modifications to the hardware. For example, an engineer might cause a program to be written to have the controller read a fluid level from a level sensor in a tank, compare the tank level with a predetermined desired level, and then open or close a feed valve based on whether the read level was lower or higher than the predetermined, desired level. The parameters are easily changed by displaying a selected view of the process and then by modifying the program using the selected view. The engineer typically would change parameters by displaying and modifying an engineer's view of the process.
In addition to executing control processes, software programs also monitor and display a view of the processes, providing feedback in the form of an operator's display or view regarding the status of particular processes. The monitoring software programs also signal an alarm when a problem occurs. Some programs display instructions or suggestions to an operator when a problem occurs. The operator who is responsible for the control process needs to view the process from his point of view. A display or console is typically provided as the interface between the microprocessor based controller or computer performing the process control function and the operator and also between the programmer or engineer and the microprocessor based controller or computer performing the process control function.
Systems that perform, monitor, control, and feed back functions in process control environments are typically implemented by software written in high-level computer programming languages such as Basic, Fortran or C and executed on a computer or controller. These high-level languages, although effective for process control programming, are not usually used or understood by process engineers, maintenance engineers, control engineers, operators and supervisors. Higher level graphical display languages have been developed for such personnel, such as continuous function block and ladder logic. Thus each of the engineers, maintenance personnel, operators, lab personnel and the like, require a graphical view of the elements of the process control system that enables them to view the system in terms relevant to their responsibilities.
For example, a process control program might be written in Fortran and require two inputs, calculate the average of the inputs and produce an output value equal to the average of the two inputs. This program could be termed the AVERAGE function and may be invoked and referenced through a graphical display for the control engineers. A typical graphical display may consist of a rectangular block having two inputs, one output, and a label designating the block as AVERAGE. A different program may be used to create a graphical representation of this same function for an operator to view the average value. Before the system is delivered to the customer, these software programs are placed into a library of predefined user selectable features.
The programs are identified by function blocks. A user may then invoke a function and select the predefined graphical representations to create different views for the operator, engineer, etc. by selecting one of a plurality of function blocks from the library for use in defining a process control solution rather than having to develop a completely new program in Fortran, for example.
A group of standardized functions, each designated by an associated function block, may be stored in a control library. A designer equipped with such a library can design process control solutions by interconnecting, on a computer display screen, various functions or elements selected with the function blocks to perform particular tasks. The microprocessor or computer associates each of the functions or elements defined by the function blocks with predefined templates stored in the library and relates each of the program functions or elements to each other according to the interconnections desired by the designer. Ideally, a designer could design an entire process control program using graphical views of predefined functions without ever writing one fine of code in Fortran or other high-level programming language.
One problem associated with the use of graphical views for process control programming is that existing systems allow only the equipment manufacturer, not a user of this equipment, to create his own control functions, along with associated graphical views, or modify the predefined functions within the provided library.
New process control functions are designed primarily by companies who sell design systems and not by the end users who may have a particular need for a function that is not a part of the standard set of functions supplied by the company. The standardized functions are contained within a control library furnished with the system to the end user. The end user must either utilize existing functions supplied with the design environment or rely on the company supplying the design environment to develop any desired particular customized function for them. If the designer is asked to modify the parameters of the engineer's view, then all other views using those parameters have to be rewritten and modified accordingly because the function program and view programs are often developed independently and are not part of an integrated development environment. Clearly, such procedure is very cumbersome, expensive, and time-consuming.
What is needed is a design environment that can easily be used, not only by a designer or manufacturer but also a user, to configure a solution to meet the specific needs of the user for developing process control functions.
SUMMARY OF THE INVENTION
It has been discovered that providing a configuration assistant system which guides a user through configuring a process control environment via a sequence of screen presentations advantageously enables a process control designer or user to quickly and easily configure a process control environment. The screen presentations may be contained within a plurality of instructional sections to further assist the process control designer in configuring the process control environment.
More specifically, in one aspect, the present invention relates to a method for configuring a process control environment. The process control environment includes a computer system having a processor coupled to a display device. The method includes the steps of providing a plurality of instructional sections, the instructional sections setting forth information relating to configuring a process control environment; presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections; and, guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations.
In another aspect, the present invention relates to a system for configuring a process control environment. The system includes a computer system, which includes a processor coupled to a memory and a display device coupled to the processor, and a plurality of instructional sections coupled to the processor, the instructional sections setting forth information relating to configuring the process control environment. The system also includes means for presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections, and means for guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations.
In another aspect, the invention relates to an article of manufacture which includes a non-volatile memory and a plurality of instructional sections stored in the non-volatile memory, the instructional sections setting forth information relating to configuring a process control environment. The article of manufacture also includes means for presenting, on the display device, a sequence of configuration screen presentations relating to the instruction sections, the means for presenting being stored in the non-volatile memory and means for guiding a user through the configuration of the process control environment via the sequence of configuration screen presentations, the means for guiding being stored in the non-volatile memory.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to copending application by Nixon et al., entitled "A Process Control System Using Standard Protocol Control of Standard Devices and Nonstandard Devices", filed on even date herewith U.S. patent application No. 08/631,862, now U.S. Pat. No. 5,828,857 which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "A Process Control System for Versatile Control of Multiple Process Devices of Various Device Types", filed on even date herewith (U.S. patent application Ser. No. 08/631,521), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "A Process Control System for Monitoring and Displaying Diagnostic Information of Multiple Distributed Devices", filed on even date herewith (U.S. patent application Ser. No. 08/631,557 ), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "Process Control System Including Automatic Sensing and Automatic Configuration of Devices", filed on even date herewith (U.S. patent application Ser. No. 08/631,519), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "A Process Control System User Interface Including Selection of Multiple Control Languages", filed on even date herewith (U.S. patent application Ser. No. 08/631,517), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "Process Control System Using a Control Strategy Implemented in a Layered Hierarchy of Control Modules", filed on even date herewith (U.S. patent application Ser. No. 08/631,520 ), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Dove et al., entitled "System for Configuring a Process Control Environment", filed on even date herewith (U.S. patent application Ser. No. 08/631,863), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "A Process Control System Using a Process Control Strategy Distributed Among Multiple Control Elements", filed on even date herewith (U.S. patent application Ser. No. 08/631,518), which application is hereby incorporated by reference in its entirety, including any appendices and references thereto.
This application is related to copending application by Nixon et al., entitled "Improved Process System ", filed on even date herewith (U.S Provisional Patent Application No. 60/017,700), which application is hereby incorporated by reference in its entirety including any appendices and references thereto.
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\documentclass[11pt]{article} \usepackage{fullpage} \usepackage{setspace} \usepackage{parskip} \usepackage{titlesec} \usepackage[section]{placeins} \usepackage{xcolor} \usepackage{breakcites} \usepackage{lineno} \usepackage{hyphenat} \usepackage{times} \PassOptionsToPackage{hyphens}{url} \usepackage[colorlinks = true, linkcolor = blue, urlcolor = blue, citecolor = blue, anchorcolor = blue]{hyperref} \usepackage{etoolbox} \makeatletter \patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{% \errmessage{\noexpand\@combinedblfloats could not be patched}% }% \makeatother \usepackage[round]{natbib} \let\cite\citep \renewenvironment{abstract} {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize} {\bigskip} \titlespacing{\section}{0pt}{*3}{*1} \titlespacing{\subsection}{0pt}{*2}{*0.5} \titlespacing{\subsubsection}{0pt}{*1.5}{0pt} \usepackage{authblk} \usepackage{graphicx} \usepackage[space]{grffile} \usepackage{latexsym} \usepackage{textcomp} \usepackage{longtable} \usepackage{tabulary} \usepackage{booktabs,array,multirow} \usepackage{amsfonts,amsmath,amssymb} \providecommand\citet{\cite} \providecommand\citep{\cite} \providecommand\citealt{\cite} % You can conditionalize code for latexml or normal latex using this. \newif\iflatexml\latexmlfalse \providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}% \AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}} \usepackage[utf8]{inputenc} \usepackage[ngerman,english]{babel} \begin{document} \title{Actionable Patient Safety Solutions \#2B: Catheter-associated Urinary Tract Infections (CAUTI)} \author[1]{Ariana Longley}% \author[2]{sbarker}% \author[2]{anna.noonan}% \author[2]{brent_d_nibarger}% \author[2]{caroline}% \author[1]{CJLillis}% \author[2]{mariadaniela.dacostapires}% \author[2]{derek}% \author[2]{edwin.loftin}% \author[2]{gleongtez}% \author[2]{haskell.helen}% \author[2]{jthomas}% \author[2]{julia}% \author[2]{kate}% \author[2]{kate.oneill}% \author[1]{Kathleen Puri}% \author[2]{kellieq44}% \author[2]{mert}% \author[2]{paul.alper}% \author[2]{peter.cox}% \author[2]{philip.stahel}% \author[2]{robin.betts}% \author[2]{sspaanbroek}% \author[2]{terry.kuzma-gottron}% \author[2]{todd.fletcher}% \author[2]{yisrael.safeek}% \author[2]{Alicia Cole}% \author[2]{greg}% \author[2]{philip.stahel}% \author[2]{emily.appleton}% \author[2]{Jonathan Coe}% \affil[1]{Patient Safety Movement Foundation}% \affil[2]{Affiliation not available}% \vspace{-1em} \date{} \begingroup \let\center\flushleft \let\endcenter\endflushleft \maketitle \endgroup \sloppy \section*{Executive Summary Checklist} {\label{994700}} In order to establish a program to eliminate~ Catheter-associated Urinary Tract Infections (CAUTI) an implementation plan~ with the following actionable steps must be completed. This checklist was adapted from the core prevention strategies recommended by the CDC~\cite{gould2010catheter}. \begin{itemize} \tightlist \item Hospital governance and senior~ administrative leadership must champion efforts to raise awareness of the high~ incidence of CAUTIs and prevention measures. \item Healthcare leadership must support~ the design and implementation of standards and training programs on catheter~ insertion and manipulation. \end{itemize} \begin{quote} \begin{itemize} \tightlist \item Insert catheters only for~ appropriate indications \item Ensure that only properly trained~ persons insert and maintain catheters \item Insert catheters using aseptic~ technique and sterile equipment \item Maintain unobstructed urine flow \item Perform~ perineal care routinely for patients who have indwelling catheters to reduce~ the risk of skin breakdown and irritation \item Remove catheters as soon as possible \end{itemize} \end{quote} \begin{itemize} \tightlist \item Following aseptic insertion,~ maintain a closed drainage system \item Senior leadership must address~ barriers, provide resources (budget/personnel), and assign accountability~ throughout the organization. \item Select technology has shown early~ success to reduce infections and/or positively enhance outcomes of patients and~ providers in frontline CAUTI~ prevention. \end{itemize} \section*{The Performance Gap} {\label{367780}} Urinary tract infections are the most common nosocomial infection,~ accounting for up to 40\% of infections reported in acute care hospitals~\cite{20004811}. There are an estimated 560,000 nosocomial UTIs annually in the United States~ with an estimated cost of \$450 million annually~\cite{Klevens_2007}. Up to 80\% of UTIs are associated with the presence of an indwelling~ urinary catheter~\cite{Apisarnthanarak_2007}. A catheter-associated urinary tract infection (CAUTI)~ increases hospital cost and is associated with increased morbidity and~ mortality~\cite{15774051,18165672,19292664}. There are an estimated 13,000 deaths annually attributable to CAUTIs~\cite{17357358}. CAUTIs are considered by the Centers for Medicare and Medicaid Services to~ represent a reasonably preventable complication of hospitalization.~ As such, no additional payment is provided to~ hospitals for CAUTI treatment-related costs. Urinary catheters are used in 15-25\% of hospitalized~ patients~\cite{10466554} and are often placed for inappropriate indications.~ According to a 2008 survey of U.S. hospitals~ \textgreater{}50\% did not monitor which patients were catheterized, and 75\% did not~ monitor duration and/or discontinuation~\cite{18171256}. The pathogenesis of CAUTIs may occur early at~ insertion or late by capillary action, or occur due to a break in the closed~ drainage tubing or contamination of collection bag urine~\cite{11294737}. The source of the organisms~may be endogenous (meatal, rectal, or vaginal colonization) or exogenous,~ usually via contaminated hands of healthcare personnel during catheter~ insertion or manipulation of the collecting system. Prevention strategies have been recommended by~ HICPAC/Centers for Disease Control and Prevention~\cite{20156062}. The Core Strategies are~ supported by high levels of scientific evidence and demonstrated feasibility,~ whereas the Supplemental strategies are supported by less robust evidence and~ have variable levels of feasibility. \subsection*{Core~ Prevention Measures include:} {\label{338333}} \begin{itemize} \tightlist \item Insert catheters only for~ appropriate indications \item Compliance~ with evidence-based guidelines e.g. Surgical Care Improvement Project (SCIP-Inf-9) requires~ urinary catheter removal on Postoperative Day 1 (POD1) or Postoperative Day 2~ (POD 2) with day of surgery being day zero \item Leave catheters in-place only as~ long as needed \item Only properly trained persons insert~ and maintain catheters \item Insert catheters using aseptic~ technique and sterile equipment \item Maintain a closed drainage system \item Maintain unobstructed urine flow \item Hand hygiene and standard (or~ appropriate) isolation precautions~~~~~~~ \end{itemize} \textbf{Supplemental Prevention Measures Include:} \begin{itemize} \tightlist \item Alternatives to indwelling urinary catheterizations \item Portable ultrasound devices to reduce unnecessary catheterizations \end{itemize} \textbf{The following practices are~NOT} \textbf{recommended for CAUTI prevention (HICPAC guidelines):} \begin{itemize} \tightlist \item Complex urinary drainage systems \item Changing catheters or drainage bags~ at routine, fixed intervals \item Routine antimicrobial prophylaxis \item Cleaning of periurethral area with~ antiseptics while catheter is in place \item Irrigation of bladder with~ antimicrobials \item Instillation of antiseptic or~ antimicrobial solutions into drainage bags \item Routine screening for asymptomatic~ bacteriuria (ASB) \end{itemize} Prior~ to the implementation of new preventive measures, an evaluation should assess~ baseline policies and procedures with regard to CAUTI.~ New policies and practices should be tracked~ once implemented to ensure adherence and to remove any barriers to effective~ change. \section*{Leadership Plan} {\label{833163}} \begin{itemize} \tightlist \item Hospital governance and senior~ administrative leadership must champion efforts in raising awareness around the~ high incidence of CAUTIs and prevention measures. \item Healthcare leadership should support~ the design and implementation of standards and training programs on catheter insertion~ and manipulation \item Senior leadership will need to~ address barriers, provide resources (budget/personnel), and assign~ accountability throughout the organization \item Leadership commitment and action are~ required at all levels for successful process improvement \end{itemize} \section*{Practice Plan} {\label{464071}} \begin{itemize} \tightlist \item Reduce the use and duration of use~ of urinary catheters \end{itemize} \begin{quote} \begin{itemize} \tightlist \item While there have been multiple~ attempts to deploy antimicrobial catheters to reduce the rate of infection,~ there is no literature to support that this technology has made a significant~ impact. \item It has been estimated that 80\% of~ hospital-acquired UTIs are directly attributable to use of an indwelling~ urethral catheter~\cite{15175612}~and studies have shown that there is a very high utilization in patients where~ it was not indicated or for durations that may have been longer than clinically~ necessary~\cite{saint2000physicians}. \item Thus the greatest opportunities to~ reduce the rate of UTI are 1) to place catheters only for appropriate~ indications and 2) to limit the duration of catheter placement. \end{itemize} \end{quote} \section*{Technology Plan} {\label{129136}} \emph{Suggested practices and technologies~ are limited to those proven to show benefit or are the only known technologies~ with a particular capability. As other options may exist, please send~ information on any additional technologies, along with appropriate evidence, to} \href{mailto:[email protected]}{\emph{[email protected]}}\emph{.} Implement an anti-infective Foley catheter kit with enhanced components to~ prepare, insert and maintain a safe urinary catheter. One standard kit that has~ been effective: \begin{itemize} \tightlist \item BARDEX\selectlanguage{ngerman}® I.C. Advance Complete Care®~ Trays \end{itemize} \section*{Metrics} {\label{560281}} \subsection*{Topic:} {\label{738126}} \textbf{Catheter-associated urinary tract infections (CAUTI)} Rate of patients with CAUTI per 1,000 urinary catheter-days - all in-patient units \subsection*{Outcome Measure Formula} {\label{113951}} \textbf{Numerator:}~Catheter-associated~ urinary tract infections based on CDC NHSN definitions for all inpatient units~\cite{centers2015urinary} \textbf{Denominator:} Total number of urinary catheter-days for all patients that have an urinary catheter in all tracked units *Rate is typically displayed as CAUTI/1,000 urinary catheter days \subsection*{Metric Recommendations} {\label{165948}} \textbf{Indirect Impact:~}All patients with conditions that lead to temporary or permanent incontinence \textbf{Direct Impact:} All patients that require a urinary catheter \textbf{Lives Spared Harm:} \[Lives\ Spared\ Harm\ =\ \left(CAUTI\ Rate_{baseline}\ -\ CAUTI\ Rate_{measurement}\right)\times\ Urinary\ Catheter\ Days_{measurement}\] \[Lives\ Saved\ =\ Lives\ Spared\ Harm\ \times\ Mortality\ Rate\] \subsection*{Notes:~} {\label{874670}} To~ meet the NHSN definitions, infections must be validated using the hospital~ acquired infection (HAI) standards~\cite{centers2015identifying}.~ Infection rates can be stratified by unit types further defined by CDC~\cite{centers2016identifying}. Infections that were present on admission (POA) are not considered HAIs and not~ counted. \textbf{Data Collection:~} CAUTI~ and urinary catheter-days can be collected through surveillance (at least once~ per month) or gathered through electronic documentation.~ Denominator documented electronically must~ match manual counts (+/- 5\%) for a 3 month validation period.~ CAUTI~ can be displayed as a Standardized Infection Ratios (SIR) using the following~ formula:~ \[SIR\ =\ \frac{Observed CAUTI}{Expected CAUTI}\] Expected infections are calculated by NHSN and available by location (unit type) from the baseline period. \subsection*{Mortality (will be calculated by the Patient Safety Movement Foundation):~} {\label{424177}} The~ PSMF, when available, will use the mortality rates associated with Hospital~ Acquired Conditions targeted in the Partnership for Patient's grant funded~ Hospital Engagement Networks (HEN). The program targeted 10 hospital acquired~ conditions to reduce medical harm and costs of care. ``At the outset of the PfP~ initiative, HHS agencies contributed their expertise to developing a~ measurement strategy by which to track national progress in patient safety---both~ in general and specifically related to the preventable HACs being addressed by~ the PfP. In conjunction with CMS's overall leadership of the PfP, AHRQ has~ helped coordinate development and use of the national measurement strategy. The~ results using this national measurement strategy have been referred to as the~ ``AHRQ National Scorecard,'' which provides summary data on the national HAC rate~(13)~\cite{agency2015efforts}. Catheter Associated Urinary Tract Infections was included in this work with~ published metric specifications. This is the most current and comprehensive~ study to date. Based on these data the~ estimated additional inpatient mortality for Catheter Associated Urinary Tract~ Infection Events is 0.023 (23 per 1000 events) \cite{ahrq2013}. \selectlanguage{english} \FloatBarrier \bibliographystyle{plainnat} \bibliography{bibliography/converted_to_latex.bib% } \end{document}
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| 0.99959 |
React Native Star Rating Component
npm version
NPM
React Native Star Rating Component
A React Native component for generating and displaying interactive star ratings. Compatible with both iOS and Android.
Table of Contents
Installation
1. install react-native-star-rating and its dependeices
npm install react-native-star-rating --save
or
yarn add react-native-star-rating
1. link react-native-vector-icons
please refer to react-native-vector-icons installation guide
Usage
Props
PropTypeDescriptionRequiredDefault
activeOpacitynumberNumber between 0 a 1 to determine the opacity of the button.No0.2
animationstringAdd an animation to the stars when upon selection. Refer to react-native-animatable for the different animation types.Noundefined
buttonStyleViewPropTypes.styleStyle of the button containing the star.No{}
containerStyleViewPropTypes.styleStyle of the element containing the star rating component.No{}
disabledboolSets the interactivity of the star buttons.Nofalse
emptyStarstring or image objectThe name of the icon to represent an empty star. Refer to react-native-vector-icons. Also can be a image object, both {uri:xxx.xxx} and require('xx/xx/xx.xxx').Nostar-o
emptyStarColorstringColor of an empty star.Nogray
fullStarstring or image objectThe name of the icon to represent a full star. Refer to react-native-vector-icons. Also can be a image object, both {uri:xxx.xxx} and require('xx/xx/xx.xxx').Nostar
fullStarColorstringColor of a filled star.Noblack
halfStarstring or image objectThe name of the icon to represent an half star. Refer to react-native-vector-icons. Also can be a image object, both {uri:xxx.xxx} and require('xx/xx/xx.xxx').Nostar-half-o
halfStarColorstringColor of a half-filled star. Defaults to fullStarColor.Noundefined
halfStarEnabledboolSets ability to select half starsNofalse
iconSetstringThe name of the icon set the star image belongs to. Refer to react-native-vector-icons.NoFontAwesome
maxStarsnumberThe maximum number of stars possible.No5
ratingnumberThe current rating to show.No0
reversedboolRenders stars from right to leftNofalse
selectedStarfunctionA function to handle star button presses.Yes() => {}
starSizenumberSize of the star.No40
starStyleViewPropTypes.styleStyle to apply to the star.No{}
For the emptyStar, fullStar, halfStar, and iconSet props, please refer to the react-native-vector-icons package for the valid string names for the star icons. When selecting the icon string names, you must remember to remove the font family name before the first hyphen. For example, if you want to use the ion-ios-star from the Ionicon font set, you would set the fullStar prop to ios-star and the iconSet to Ionicons.
For the animation prop, please refer to the react-native-animatable package for valid string names for the different animations available.
General Star Example
The following example will render 3.5 stars out of 5 stars using the star-o for the empty star icon, star-half-o for the half star icon, and star for the full star icon from the FontAwesome icon set in black color.
import StarRating from 'react-native-star-rating';
class GeneralStarExample extends Component {
constructor(props) {
super(props);
this.state = {
starCount: 3.5
};
}
onStarRatingPress(rating) {
this.setState({
starCount: rating
});
}
render() {
return (
<StarRating
disabled={false}
maxStars={5}
rating={this.state.starCount}
selectedStar={(rating) => this.onStarRatingPress(rating)}
/>
);
}
}
export default GeneralStarExample
General Star Example
Custom Star Case
The following example will render 2.5 stars out of 7 stars using the ios-star-outline for the empty star icon, ios-star-half for the half star icon, and ios-star for the full star icon from the Ionicons icon set in red color.
import StarRating from 'react-native-star-rating';
class CustomStarExample extends Component {
constructor(props) {
super(props);
this.state = {
starCount: 2.5
};
}
onStarRatingPress(rating) {
this.setState({
starCount: rating
});
}
render() {
return (
<StarRating
disabled={false}
emptyStar={'ios-star-outline'}
fullStar={'ios-star'}
halfStar={'ios-star-half'}
iconSet={'Ionicons'}
maxStars={7}
rating={this.state.starCount}
selectedStar={(rating) => this.onStarRatingPress(rating)}
fullStarColor={'red'}
/>
);
}
}
export default CustomStarExample
Custom Star Example
Running the ExampleApp (WIP)
Navigate to the root of the ExampleApp and install the dependencies
cd ExampleApp && npm install
Run the app on the iOS simulator.
npm run ios
Development Setup (WIP)
Be sure to have create-react-native-app installed.
npm install -g create-react-native-app
Create a development app in the root folder.
create-react-native-app DevelopmentApp
Going into the development app and clone this repo.
cd DevelopmentApp && git clone https://github.com/djchie/react-native-star-rating.git
Go into the react-native-star-rating directory and start developing!
cd react-native-star-rating
Roadmap
View the project roadmap here
Contributing
See CONTRIBUTING.md for contribution guidelines.
Check it on GitHub
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| 0.541081 |
Improving privacy and security in decentralized ciphertext-policy attribute-based encryption
Jinguang Han, Willy Susilo, Yi Mu, Jianying Zhou, Man Ho Allen Au
Research output: Journal article publicationJournal articleAcademic researchpeer-review
104 Citations (Scopus)
Abstract
In previous privacy-preserving multiauthority attribute-based encryption (PPMA-ABE) schemes, a user can acquire secret keys from multiple authorities with them knowing his/her attributes and furthermore, a central authority is required. Notably, a user's identity information can be extracted from his/her some sensitive attributes. Hence, existing PPMA-ABE schemes cannot fully protect users' privacy as multiple authorities can collaborate to identify a user by collecting and analyzing his attributes. Moreover, ciphertext-policy ABE (CP-ABE) is a more efficient public-key encryption, where the encryptor can select flexible access structures to encrypt messages. Therefore, a challenging and important work is to construct a PPMA-ABE scheme where there is no necessity of having the central authority and furthermore, both the identifiers and the attributes can be protected to be known by the authorities. In this paper, a privacy-preserving decentralized CP-ABE (PPDCP-ABE) is proposed to reduce the trust on the central authority and protect users' privacy. In our PPDCP-ABE scheme, each authority can work independently without any collaboration to initial the system and issue secret keys to users. Furthermore, a user can obtain secret keys from multiple authorities without them knowing anything about his global identifier and attributes.
Original languageEnglish
Article number6987293
Pages (from-to)665-678
Number of pages14
JournalIEEE Transactions on Information Forensics and Security
Volume10
Issue number3
DOIs
Publication statusPublished - 1 Mar 2015
Keywords
• CP-ABE
• decentralization
• privacy
ASJC Scopus subject areas
• Safety, Risk, Reliability and Quality
• Computer Networks and Communications
Cite this
|
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| 0.884039 |
I2E: Event-Driven Programming and Agents
The division of roles in object technology is clear: of the two principal constituents of a system, object types and operations, the first dominates. Classes, representing object types, determines the structure of the software; every routine, representing an operation, belongs to a class.
In some circumstances it is useful to define an object that denotes an operation. This is especially useful if you want to build an object structure that refers to operations, so that you can later traverse the structure and execute the operations encountered. A typical application is event-driven programming for Graphical User Interfaces (GUI), including Web programming. In GUI programming you will want to record properties of the form "When the user clicks this OK button, the system must update the file"
each involves a control (here the OK button), an event (mouse click) and an operation (update the file). This can be programmed by having an "event loop", triggered for each event, which performs massive decision-making (if "The latest event was `left mouse click on button 23'" then "Appropriate instructions" else if ... and so on with many branches); but this leads to bulky software architectures where introducing any new control or event requires updating a central part of the code. It's preferable to let any element of the system that encounters a new control-event-operation association [control, event, operation]
store it as a triple of objects into an object structure, such as an array or a list. Triples in that structure may come from different parts of the system; there is no central know-it-all structure. The only central element is a simple mechanism which can explore the object structure to execute each operation associated with a certain control and a certain event. The mechanism is not just simple; it's also independent of your application, since it doesn't need to know about any particular control, event or operation (it will find them in the object structure). So it can be programmed once and for all, as part of a library such as EiffelVision 2 for platform-independent graphics.
To build an object structure, we need objects. A control, an event are indeed objects. But an operation is not: it's program code -- a routine of a certain class.
Agents address this issue. An agent is an object that represents a routine, which can then be kept in an object structure. The simplest form of agent is written agent r, where r is a routine. This denotes an object. If your_agent is such an agent object, the call your_agent.call ([a, b])
where a and b are valid arguments for r, will have the same effect as a direct call to r with arguments a and b. Of course, if you know that you want to call r with those arguments, you don't need any agents; just use the direct call r (a, b). The benefit of using an agent is that you can store it into an object structure to be called later, for example when an event-driven mechanism finds the agent in the object structure, associated with a certain control and a certain event. For this reason agents are also called delayed calls.
Info: The notation [a, b] denotes a sequence of elements, or tuple. The reason call needs a tuple as argument, whereas the direct call r (a, b) doesn't, is that call is a general routine (from the EiffelBase class ROUTINE, representing agents) applicable to any agent, whereas the direct call refers explicitly to r and hence requires arguments a and b of specific types. The agent mechanism, however, is statically typed like the rest of the language; when you call call, the type checking mechanism ensures that the tuple you pass as argument contains elements a and b of the appropriate types.
A typical use of agents with EiffelVision 2 is ok_button.select_actions.extend (agent your_routine)
which says: "add your_routine to the list of operations to be performed whenever a select event (left click) happens on ok_button". ok_button.select_actions is the list of agents associated with the button and the event; in list classes, procedure extend adds an item at the end of a list. Here, the object to be added is the agent.
This enables the EiffelVision 2 event-handling mechanism to find the appropriate agent when it processes an event, and call call on that agent to trigger the appropriate routine. EiffelVision 2 doesn't know that it's your_routine; in fact, it doesn't know anything about your application. It simply finds an agent in the list, and calls call on it. For your part, as the author of a graphical application, you don't need to know how EiffelVision 2 handles events; you simply associate the desired agents with the desired controls and events, and let EiffelVision 2 do the rest.
Agents extend to many areas beyond GUIs. In numerical computation, you may use an agent to pass to an "integrator" object a numerical function to be integrated over a certain interval. In yet another area, you can use agents (as in the iteration library of EiffelBase) to program iterators : mechanisms that repetitively apply an arbitrary operation -- represented by an agent -- to every element of a list, tree or other object structure. More generally, agent embody properties of the associated routines, opening the way to mechanism for reflection, also called "introspection": the ability, during software execution, to discover properties of the software itself.
cached: 02/22/2018 10:08:48.000 PM
|
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| 0.851633 |
How to make a function that returns a promise works correctly in a forEach loop?
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Since a function that returns a promise is asynchronous, how would you use it inside of a forEach loop? The forEach loop will almost always finish before the data being fetched or manipulated by the promise returning function can complete its data manipulation.
Here is an example of some code where I am having this problem.
var todaysTopItemsBySaleFrequency = [];
listOfItemIdsAndSaleFrequency.forEach((item) => {
Product.findById(item.itemId).then((foundItem) => {
var fullItemData = foundItem.toJSON();
fullItemData.occurrences = item.occurrences;
todaysTopItemsBySaleFrequency.push(fullItemData);
});
});
return res.status(200).json(todaysTopItemsBySaleFrequency);
The array called todaysTopItemsBySaleFrequency is sent back to the client empty. findById is a mongoose function which returns a promise, so it doesn't fully populate the array by the time the response is sent back to the client.
You cannot use a forEach loop, as that works only with functions that don't return anything. If they return something, or a promise for it, you'll have to use a map loop. You then can use Promise.all on the result, the array of promises:
Promise.all(listOfItemIdsAndSaleFrequency.map(item =>
Product.findById(item.itemId).then(foundItem => {
var fullItemData = foundItem.toJSON();
fullItemData.occurrences = item.occurrences;
return fullItemData;
})
)).then(todaysTopItemsBySaleFrequency => {
res.status(200).json(todaysTopItemsBySaleFrequency);
})
|
__label__pos
| 0.907059 |
Select Page
According to a survey, there are around 80 sleep disorders in the world, though the exact number of classification has not yet mentioned. Most people sometimes experience sleep problems due to stress, busy schedules, and other outside influences. However, when these problems begin to occur regularly and interfere with daily life, they may indicate a sleep disorder.
In this blog post, we will discuss about various sleep disorder and its causes
Sleep Disorder Psychology
Most of the sleep doctors or sleep specialist use one of the two major system to check the specific sleep disorder. The two major system are
• The diagnostic and statistical manual of mental disorder
• The internal classification of sleep disorder
Depending on the type of sleep disorder, people may find it difficult in falling asleep and may feel extremely tired and irritate throughout the day. Lack of sleep or incomplete rest to the body can have a negative impact on mood, concentration and overall health.
In some of the cases, sleep disorders can also be a symptom of another medical or mental problems. These sleep problems may eventually disappear once the treatment is obtained for the underlying cause. When another condition is not responsible for sleep disorder, sleep disorder treatment normally involves a combination of medical treatments and some changes in lifestyles.
It is important to get a diagnosis and treatment immediately if you suspect that you may have a sleep disorder. When not treated, the negative effects of sleep disturbances can lead to other health consequences. They can also affect your performance when you are at work, it can cause tension in relationships and affect your ability to perform daily activities.
List of Sleep Disorder
There are a large number of sleep disorders in the worlds, out of which the most commons are listed below
• Insomnia
• Snoring
• Allergies and respiratory problems
• Nocturia
• Chronic Pain
• Stress and anxiety
• REM Sleep Disorder
• Sleepwalking
• Sleeptalking
• Nightmares
Insomnia: Most Common Sleep Disorder
Also known as sleeplessness, is a sleep disorder symptoms where people have difficulty falling asleep or staying asleep for as long as desired. Insomnia result in daytime sleepiness, lack of energy, irritation and depressed mood. This can lead to an increased risk of accidents, as well as problems of concentration and learning. Insomnia can be short term, for days or weeks, or long-term, for more than a month. There are two types of insomnia
• Acute insomnia – Which does not occur for a longer period and generally appears for a shorter period of time. This type of insomnia is not a major threat to health issues and other life concerns
• Chronic insomnia – This type of insomnia generally occurs for a longer period and it can affect the health and personal life in many ways. One should immediately contact professional doctors to resolve this problem as quickly as possible
Other Types Of Sleep Disorder
Snoring
If you live alone and it does not disturb your sleep, this may not be a major problem for you. But if it wakes you up, causing a bad sleep, or disturbs your sleep partner, then this is a more obvious problem.
Surveys have shown that partners of people who snore may suffer from poor health due to disturbed sleep. Sometimes it resorts to another common solution– like sleeping in a different room.
There is also evidence that snoring could get worse over time if it is not controlled. Prolonged snoring can damage the blood vessels of your muscles, which further reduces control and makes your snoring worse.
Allergies and respiratory problem
Allergies, upper respiratory infections or colds can make you difficult to breathe. The inability of breathing from your nose can also cause the sleep disorder.
Nocturia
Nocturia, or frequent urination, can disturb your sleep by making you wake up during the night. Hormonal imbalances and urinary tract diseases can contribute to the development of this disease. Make sure you call the doctor immediately if frequent urination is accompanied by bleeding or pain.
Chronic pain
Sometimes when you fall asleep and you wake up suddenly because of pain, or that pain does not let you sleep, then you are suffering from chronic pain.
Some of the most common causes are
• Arthritis
• Fibromyalgia
• Persistent headaches
• Continuous lower back pain
• Inflammatory bowel disease
Stress and anxiety
Sometimes stress and tensions can lead to a negative impact on sleep quality and does not let you sleep properly.
REM sleep disorder
For most people, dreaming is purely a “mental” activity: Dreams occur in the mind while the body is at rest. But people who suffer from paradoxical sleep disorder (RBD) Act their dreams. They physically move members or even get up and engage in activities associated with waking up. Some fall asleep talking, shouting, screaming, patting or punching. Some even fly out of bed in sleep! The RBD is usually noticed when it presents a danger to the sleeping person, his or her bed partner or other people she meets. Sometimes, adverse effects such as injuries sustained by the partner or partner during their sleep trigger a diagnosis of RBD. The good news is that RBD can usually be treated successfully.
So, for most people, even when they have vivid dreams in which they imagine themselves to be active, their bodies are motionless. But people suffering from RBD do not have this muscular paralysis, which allows them to express dramatic and/or violent dreams during REM sleep. Sometimes they start by talking, twisting and jerking themselves during their dreams for years before fully realising their REM dreams.
Sleep talking
Sleep talking is a sleep disorder defined as a conversation during sleep without being aware of it. Sleeping can involve complicated dialogues or monologue, complete gibberish or mumbling. The good news is that for most people it is a rare and short-lived event. Anyone can experience talking sleep, but the condition is more common in males and children.
Sleeptalking are not generally aware of their behaviour or words; Therefore, their voices and the type of language they use may seem different from their awakened speech. Talking can be spontaneous or induced by a conversation with the sleeper.
Sleep walking
It is a behavioral disorder that occurs during deep sleep and leads to the walking or execution of other complex behaviours during sleep. It is much more common in children than adults and is more likely to occur if a person is deprived of sleep. Because a sleepwalker usually stays deeply asleep throughout the episode, it can be difficult to wake up and probably will not remember the sleepwalking incident.
Sleepwalking usually involves more than just walking during sleep; It is a series of complex behaviors that take place during sleep, the most obvious of which is walking. The symptoms of sleepwalking range from simply sitting in bed and looking around, walking in the room or home, leaving the house and even travelling long distances. It’s a common misconception that a sleepwalker shouldn’t be awake. In fact, it can be dangerous enough not to wake a sleepwalker.
Nightmares
Nightmares are dreams with vivid and disturbing content. They are more common in children during REM sleep, but they can also happen to adults. They usually involve an immediate awakening and a good reminder of the dream. Nocturnal terrors, also widespread in children, are often described as extreme nightmares that occur during non-REM sleep.
Nocturnal terrors have common characteristics. They usually include excitement, agitation, large pupils, perspiration and increased blood pressure. Usually the child cries out and seems terrified for several minutes until they end up relaxing and going back to sleep. Nocturnal terrors usually occur early in the night and may be associated with sleepwalking. The child usually does not remember or has only a vague memory of his dream.
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Sample records for ac underground cable
1. Online Location of Faults on AC Cables in Underground Transmission Systems
Jensen, Christian Flytkjær
2013-01-01
A transmission grid is normally laid out as an almost pure overhead line (OHL) network. The introduction of transmission voltage level XLPE cables and the increasing interest in the environmental impact of OHL has resulted in an increasing interest in the use of underground cables on transmission level. In Denmark for instance, the entire 150 kV, 132 kV and 220 kV and parts of the 400 kV transmission network will be placed underground before 2030.To reduce the operating losses of a cable-base...
2. Superconducting ac cable
The components of a superconducting 110 kV ac cable for power ratings >= 2000 MVA have been developed. The cable design especially considered was of the semiflexible type, with a rigid cryogenic envelope and flexible hollow coaxial cable cores pulled into the former. The cable core consists of spirally wound Nb-Al composite wires and a HDPE-tape wrapped electrical insulation. A 35 m long single phase test cable with full load terminations for 110 kV and 10 kA was constructed and successfully tested. The results obtained prove the technical feasibility and capability of our cable design. (orig.)
3. Online Fault Location on AC Cables in Underground Transmission Systems using Sheath Currents
Jensen, Christian Flytkjær; Nanayakkarab, Kasun; Rajapakse, Athula;
2014-01-01
This paper studies online travelling wave methods for fault location on a crossbonded cable system using sheath currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. At...
4. Online Location of Faults on AC Cables in Underground Transmission Systems
Jensen, Christian Flytkjær
deviations in the parameters of the OHL will result in large errors for fault location in the cable section. Field measurements showing the effect of short circuits on crossbonded systems conducted on parts of the electrical connection to the Anholt offshore wind farm are performed. The purpose is to examine...... whether neural networks can be trained using data from state-of-theart cable models to predict and estimate the fault location on crossbonded cables. Numerous measurements of different short circuits are carried out and it is concluded that the state-ofthe-art models predict general behaviour of the...... crossbonded system under fault conditions well, but the accuracy of the calculated impedance is low for fault location purposes. The neural networks can therefore not be trained and no impedance-based fault location method can be used for crossbonded cables or hybrid lines. The use of travelling wave...
5. Online fault location on crossbonded AC cables in underground transmission systems
F. Jensen, Christian; Bak, Claus Leth; Gudmundsdottir, Unnur Stella
2014-01-01
In this paper, a fault locator system specifically designed for crossbonded cables is described. Electromagnetic wave propagation theory for crossbonded cables with focus on fault location purposes is discussed. Based on this, the most optimal modal component and input signal to the fault locator system are identified. The fault locator system uses the Wavelet Transform both to create reliable triggers in the units and to estimate the fault location based on time domain signals obtained in th...
6. High Temperature Superconducting Underground Cable
Farrell, Roger, A.
2010-02-28
The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.
7. High Temperature Superconducting Underground Cable
The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the worlds first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.
8. Online fault location on crossbonded AC cables in underground transmission systems
F. Jensen, Christian; Bak, Claus Leth; Gudmundsdottir, Unnur Stella
2014-01-01
of a 245 kV crossbonded cable system, connecting the newly installed 400 MW Danish offshore wind farm Anholt to the main grid, are obtained and used to verify the proposed system. Furthermore, extensive simulation data created in PSCAD/EMTDC is used in order to examine the robustness of the system to......In this paper, a fault locator system specifically designed for crossbonded cables is described. Electromagnetic wave propagation theory for crossbonded cables with focus on fault location purposes is discussed. Based on this, the most optimal modal component and input signal to the fault locator...... system are identified. The fault locator system uses the Wavelet Transform both to create reliable triggers in the units and to estimate the fault location based on time domain signals obtained in the substations by two fault locator units. Field measurements of faults artificially created on a section...
9. Online fault location on AC cables in underground transmission systems using screen currents
Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula;
This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. At...... coils if the screen currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and visual inspection methods are used and the accuracy is compared. Field measurements...
10. 47 CFR 32.2422 - Underground cable.
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Underground cable. 32.2422 Section 32.2422... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2422 Underground cable. (a) This account shall include the original cost of underground cable installed in conduit and...
11. EHV AC undergrounding electrical power performance and planning
Benato, Roberto
2010-01-01
EHV AC Undergrounding Electrical Power discusses methods of analysis for cable performance and for the behaviour of cable, mixed and overhead lines. The authors discuss the undergrounding of electrical power and develop procedures based on the standard equations of transmission lines. They also provide technical and economical comparisons of a variety of cables and analysis methods, in order to examine the performance of AC power transmission systems. A range of topics are covered, including: energization and de-energization phenomena of transmission lines; power quality; and cable safety cons
12. Modeling of long High Voltage AC Underground
Gudmundsdottir, Unnur Stella; Bak, Claus Leth; Wiechowski, W. T.
2010-01-01
This paper presents the work and findings of a PhD project focused on accurate high frequency modelling of long High Voltage AC Underground cables. The project is cooperation between Aalborg University and Energinet.dk. The objective of the project is to investigate the accuracy of most up to date...... cable models, perform highly accurate field measurements for validating the model and identifying possible disadvantages of the cable model. Furthermore the project suggests and implements improvements and validates them against several field measurements. It is shown in this paper how a new method for...... calculating the frequency dependent cables impedance greatly improves the modeling procedure and gives a highly accurate result for high frequency simulations....
13. 30 CFR 75.804 - Underground high-voltage cables.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground high-voltage cables. 75.804 Section... AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.804 Underground high-voltage cables. (a) Underground high-voltage cables used in...
14. 30 CFR 57.4057 - Underground trailing cables.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground trailing cables. 57.4057 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Fire Prevention and Control § 57.4057 Underground trailing cables. Underground trailing cables shall be accepted...
15. 47 CFR 32.6422 - Underground cable expense.
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Underground cable expense. 32.6422 Section 32.6422 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM... Underground cable expense. (a) This account shall include expenses associated with underground cable....
16. AC loss in superconducting tapes and cables
Oomen, Marijn Pieter
2000-01-01
The present study discusses the AC loss in high-temperature superconductors. Superconducting materials with a relatively high critical temperature were discovered in 1986. They are presently developed for use in large-scale power-engineering devices such as power-transmission cables, transformers an
17. Comparison of advanced high power underground cable designs
In this paper, advanced high power underground cable designs are compared in the light of available literature, of reports and information supplied by participating industries (AEG, BICC, CGE, Pirelli, Siemens), spontaneous contributions by EdF, France, BBC and Felten and Guilleaume Kabelwerke A.G., Germany, and Hitachi, Furukawa, Fujikura and Sumitomo, Japan, and earlier studies carried out at German public research centres. The study covers cables with forced cooling by oil or water, SF6-cables, polyethylene cables, cryoresistive and superconducting cables. (orig.)
18. AC loss in superconducting tapes and cables
Oomen, Marijn Pieter
High-temperature superconductors are developed for use in power-transmission cables, transformers and motors. The alternating magnetic field in these devices causes AC loss, which is a critical factor in the design. The study focuses on multi-filament Bi-2223/Ag tapes exposed to a 50-Hz magnetic field at 77 K. The AC loss is measured with magnetic, electric and calorimetric methods. The results are compared to theoretical predictions based mainly on the Critical-State Model. The loss in high- temperature superconductors is affected by their characteristic properties: increased flux creep, high aspect ratio and inhomogeneties. Filament intergrowths and a low matrix resistivity cause a high coupling-current loss especially when the filaments are fully coupled. When the wide side of the tape is parallel to the external magnetic field, the filaments are decoupled by twisting. In a perpendicular field the filaments can be decoupled only by combining a short twist pitch with a transverse resistivity much higher than that of silver. The arrangement of the inner filaments determines the transverse resistivity. Ceramic barriers around the filaments cause partial decoupling in perpendicular magnetic fields at power frequencies. The resultant decrease in AC loss is greater than the accompanying decrease in critical current. With direct transport current in alternating magnetic field, the transport-current loss is well described with a new model for the dynamic resistance. The Critical- State Model describes well the magnetisation and total AC loss in parallel magnetic fields, at transport currents up to 0.7 times the critical current. When tapes are stacked face-to-face in a winding, the AC-loss density in perpendicular fields is greatly decreased due to the mutual shielding of the tapes. Coupling currents between the tapes in a cable cause an extra AC loss, which is reduced by a careful cable design. The total AC loss in complex devices with many tapes is generally well
19. Development of YBCO HTS cable with low AC loss
High temperature superconducting (HTS) cables using YBCO tapes are expected to be more economical because AC losses will be much smaller than conventional cables. To reduce AC loss, 10 mm wide YBCO tapes were divided into five strips using a YAG laser. Using narrower strips and optimizing the space between the strips were effective in reducing AC loss. A 1 m conductor was fabricated, and AC loss was 0.048 W/m at 1 kA and 50 Hz. Based on the successful AC loss reduction in the 1 m conductor, we will fabricate a 10 m HTS cable with a three-layer HTS conductor, electrical insulation, and a one-layer HTS shield and cupper protection layer for overcurrent. In addition, we have developed a prototype of the HTS cable joint that can withstand an overcurrent condition of 31.5 kA for 2 s
20. 30 CFR 75.822 - Underground high-voltage longwall cables.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground high-voltage longwall cables. 75... MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.822 Underground high-voltage longwall cables. In addition to the...
1. Energy dispatching analysis of lightning surges on underground cables in a cable connection station
The paper aimed to simulate the transient over-voltage phenomena which occur at 345 kV and 161 kV underground cables, when lighting strikes on or near the cable connection station, by using the Electro-Magnetic Transients Program (EMTP). A feasibility study on changing related parameters, as well as cable connections and grounding methods to reduce the impact caused by lightning strikes, will be thoroughly conducted. The various components required for a detailed simulation including; lightning surges, transmission line and tower, arrester, and underground cables are all considered. Then, the transient voltage of the cables will be analyzed under different situations including; connection methods, grounding locations, length of the grounding wire of arrester, and the grounding resistance for different locations. The simulation results show that the length of the grounding wire is more sensitive to the transient over-voltage which occurred when a common grounding topology was adopted. In contrast, the use of an independent grounding topology resulted in a reduction of the grounding resistance, which effectively decreased the over-voltage, thereby avoiding surpassing the shielding voltage level of the cable, caused by the rise of ground voltage.
2. Assessment of 69 kV Underground Cable Thermal Ratings using Distributed Temperature Sensing
Stowers, Travis
Underground transmission cables in power systems are less likely to experience electrical faults, however, resulting outage times are much greater in the event that a failure does occur. Unlike overhead lines, underground cables are not self-healing from flashover events. The faulted section must be located and repaired before the line can be put back into service. Since this will often require excavation of the underground duct bank, the procedure to repair the faulted section is both costly and time consuming. These added complications are the prime motivators for developing accurate and reliable ratings for underground cable circuits. This work will review the methods by which power ratings, or ampacity, for underground cables are determined and then evaluate those ratings by making comparison with measured data taken from an underground 69 kV cable, which is part of the Salt River Project (SRP) power subtransmission system. The process of acquiring, installing, and commissioning the temperature monitoring system is covered in detail as well. The collected data are also used to evaluate typical assumptions made when determining underground cable ratings such as cable hot-spot location and ambient temperatures. Analysis results show that the commonly made assumption that the deepest portion of an underground power cable installation will be the hot-spot location does not always hold true. It is shown that distributed cable temperature measurements can be used to locate the proper line segment to be used for cable ampacity calculations.
3. Comparative Analysis of Thermography Studies and Electrical Measurement of Partial Discharges in Underground Power Cables
Gonzalez-Parada, A.; Guzman-Cabrera, R.; Torres-Cisneros, M.; Guzman-Sepulveda, J. R.
2015-09-01
The principal cause of damage in underground power cable installations is partial discharge (PD) activity. PD is a localized non-linear phenomenon of electrical breakdown that occurs in the insulating medium sitting between two conducting materials, which are at different potentials. The damage to the insulating material is induced by the AC voltage to which the insulator is subjected during the discharge process, and it can be directly or indirectly measured by the charge displacement across the insulation and the cavity defect. Non-invasive detection techniques that help in identifying the onset of the discharge process are required as PD is a major issue in terms of maintenance and performance of underground power installations. The main locations of failure are the accessories at points of connection such as terminals or splices. In this article, a study of electrical detection of PD and image processing of thermal pictures is presented. The study was carried out by controllably inducing specific failures in the accessories of the installation. The temporal evolution of the PD signals was supported with thermal images taken during the test in order to compare the PD activity and thermal increase due to failure. The analysis of thermographic images allows location of the failure by means of intensity-based texture segmentation algorithms. This novel technique was found to be suitable for non-invasive detection of the PD activity in underground power cable accessories.
4. Narrow strand YBCO Roebel cable for lowered AC loss
We have constructed test lengths of Roebel cable from wide strips of second generation YBCO wire. The strand width is 2mm to allow for lowered AC losses in comparison with standard HTS wires. Up to 10 strands can be cut from the 40mm wide strip and assembled into a 10 strand cable with a transposition length of 90mm. Electrical measurements show good retention of critical current through the cutting and cabling processes. Initial AC loss measurements confirm the reduction expected from full width wire. Results from mechanical modeling are presented which have been used to optimise strand geometry to reduce stress concentrations. Manufacturing capability to produce up to 100m lengths has been demonstrated
5. Experimental investigation of a.c. losses in cabled superconductors
A.c. losses in multifilamentary composite superconducting strands and cables have been measured in adiabatic conditions for transverse field sweep rates up to 50 T s-1. Measurements were performed on NbTi and Nb3Sn conductors of several configurations and surface preparations: single strands, soldered strands and cables of varying degrees of compaction composed of bare strands, with CuNi barriers and strands with chrome plating. The experimental data agree well with existing loss models. The data suggests that the total cable loss grows as approx.= 1/(void)3 below void fractions of 40%. This observed cable loss dependence on void fraction does not agree well with a previously proposed model. (author)
6. Non-invasive monitoring of underground power cables using Gaussian-enveloped chirp reflectometry
In this paper, we introduce non-invasive Gaussian-enveloped linear chirp (GELC) reflectometry for the diagnosis of live underground power cables. The GELC reflectometry system transmits the incident signal to live underground power cables via an inductive coupler. To improve the spatial resolution of the GELC reflectometry, we used the multiple signal classification method, which is a super-resolution method. An equalizer, which is based on Wiener filtering, is used to compensate for the signal distortion due to the propagation characteristics of underground power cables and inductive couplers. The proposed method makes it possible to detect impedance discontinuities in live underground power cables with high spatial resolution. Experiments to find the impedance discontinuity in a live underground power cable were conducted to verify the performance of the proposed method. (paper)
7. Research on communication system of underground safety management based on leaky feeder cable
CHEN Jian-hong; ZHANG Tao; CHENG Yun-cai; ZHANG Han
2007-01-01
According to the current working status of underground safety management and production scheduling, the importance and existed problem of underground mine radio communication were summarized, and the basic principle and classification of leaky feeder cable were introduced and the characteristics of cable were analyzed specifically in depth, and the application model of radio communication system for underground mine safety management was put forward. Meanwhile, the research explanation of the system component, function and evaluation was provided. The discussion result indicates that communication system of underground mine safety management which is integrated two-way relay amplifier and other equipment has many communication functions, and underground mine mobile communication can be achieved well.
8. Low AC Loss in a 3 kA HTS Cable of the Dutch Project
Chevtchenko, Oleg; Zuijderduin, Roy; Smit, Johan; Willén, Dag; Lentge, Heidi; Thidemann, Carsten; Traeholt, Chresten; Melnik, Irina; Geschiere, Alex
2012-01-01
Requirements for a 6km long high temperature superconducting (HTS) AC power cable of the Amsterdam project are: a cable has to fit in an annulus of 160mm, with two cooling stations at the cable ends only. Existing solutions for HTS cables would lead to excessively high coolant pressure drop in th...
9. Models for electromagnetic coupling of lightning onto multiconductor cables in underground cavities
Higgins, Matthew Benjamin
This dissertation documents the measurements, analytical modeling, and numerical modeling of electromagnetic transfer functions to quantify the ability of cloud-to-ground lightning strokes (including horizontal arc-channel components) to couple electromagnetic energy onto multiconductor cables in an underground cavity. Measurements were performed at the Sago coal mine located near Buckhannon, WV. These transfer functions, coupled with mathematical representations of lightning strokes, are then used to predict electric fields within the mine and induced voltages on a cable that was left abandoned in the sealed area of the Sago mine. If voltages reached high enough levels, electrical arcing could have occurred from the abandoned cable. Electrical arcing is known to be an effective ignition source for explosive gas mixtures. Two coupling mechanisms were measured: direct and indirect drive. Direct coupling results from the injection or induction of lightning current onto metallic conductors such as the conveyors, rails, trolley communications cable, and AC power shields that connect from the outside of the mine to locations deep within the mine. Indirect coupling results from electromagnetic field propagation through the earth as a result of a cloud-to-ground lightning stroke or a long, low-altitude horizontal current channel from a cloud-to-ground stroke. Unlike direct coupling, indirect coupling does not require metallic conductors in a continuous path from the surface to areas internal to the mine. Results from the indirect coupling measurements and analysis are of great concern. The field measurements, modeling, and analysis indicate that significant energy can be coupled directly into the sealed area of the mine. Due to the relatively low frequency content of lightning (< 100 kHz), electromagnetic energy can readily propagate through hundreds of feet of earth. Indirect transfer function measurements compare extremely well with analytical and computational models
10. Installation of underground power transmission cables. Proceedings of a Department of Energy workshop
None
1979-06-01
The proceedings of a Department of Energy-sponsored workshop in the installation of underground power transmission cables are reported. The workshop was held in Pittsburgh, Pennsylvania, October 2--5, 1978. Sixty-two participants, representing equipment manufacturers, utilities, contractors, universities, and government agencies, were divided into topic groups covering specific installation activities. Discussion was directed toward a review of the state of the art in underground cable installation, future equipment and technique development requirements, and the formulation of conclusions and recommendations. The principal technological problem for underground installation is the lack of ability to locate underground obstacles, principally in urban and suburban areas. Development of a sensing system to locate obstacles was given a high priority by nearly all topic groups. The lack of market definition was seen as the principal impediment to competition and development of specialized equipment. Most participants felt that the federal government must assume a role in research and development of new equipment and techniques. However, the participants did not favor increased federal regulation of underground cable installation systems.
11. A Study on the Thermal Effect of the Current-Carrying Capacity of Embedded Underground Cable
LI Dewen
2012-10-01
Full Text Available The current paper aims to study embedded underground cable and the effect of temperature that surrounds it. Determining the carrying capacity of the cable is important to predict the temperature changesin the embedded pipe. Simulating the temperature field and the laying environment according to the IEC standard enables the calculation of the carrying capacity of the buried region. According to the theoryof heat transfer, the embedded pipe tube model temperature field should be coupled with a numerical model. The domain and boundary conditions of the temperature field should also be determined using the 8.7/15kV YJV 400 cable. In conducting numerical calculation and analysis using the temperature field model, the two-dimensional temperature distribution of the emission control area should be determined. The experimental results show that the simulation isconsistent with the IEC standard. Furthermore, in identifying the cable ampacity, the different seasons and different cable rows should be taken into account using the finite element method. Finally, theappropriate choice of root and circuit numbers of the cable will improve the cable’s the carrying capacity.
12. Detection and Location of Underground Power Cable using Magnetic Field Technologies
Wang, P.; Goddard, K.F.; Lewin, P L; Swingler, S.G
2011-01-01
The location of buried underground electricity cables is becoming a major engineering and social issue worldwide. Records of utility locations are relatively scant, and even when records are available, they almost always refer to positions relative to ground-level physical features that may no longer exist or that may have been moved or altered. The lack of accurate positioning records of existing services can cause engineering and construction delays and safety hazards when new construction,...
13. The scaling of transport AC losses in Roebel cables with varying strand parameters
A Roebel cable is a good candidate for low-voltage windings in a high-temperature superconductor (HTS) transformer because of its high current-carrying capability and low AC loss. Transport AC loss measurements were carried out in 1.8 m long 15/5 (fifteen 5 mm wide strands) and 15/4 Roebel cables. The results were compared with those in many Roebel cables composed of 2 mm wide Roebel strands. Comparison of the AC losses hinted that the intrinsic difference in normalized transport AC losses is due to differences in the g/w (ratio of the horizontal gap between the Roebel strands over the Roebel strand width) values. The intrinsic difference was confirmed by measuring transport AC loss in a series of horizontally arranged parallel conductor pairs with various g values. A method to scale transport AC losses in Roebel cables with varying strand parameters was developed. The scaling method will be useful for a rough assessment of AC loss in one-layer solenoid winding coils, such as in a HTS transformer. (papers)
14. Development and Improvement of an Intelligent Cable Monitoring System for Underground Distribution Networks Using Distributed Temperature Sensing
Jintae Cho
2014-02-01
Full Text Available With power systems switching to smart grids, real-time and on-line monitoring technologies for underground distribution power cables have become a priority. Most distribution components have been developed with self-diagnostic sensors to realize self-healing, one of the smart grid functions in a distribution network. Nonetheless, implementing a real-time and on-line monitoring system for underground distribution cables has been difficult because of high cost and low sensitivity. Nowadays, optical fiber composite power cables (OFCPCs are being considered for communication and power delivery to cope with the increasing communication load in a distribution network. Therefore, the application of distributed temperature sensing (DTS technology on OFCPCs used as underground distribution lines is studied for the real-time and on-line monitoring of the underground distribution power cables. Faults can be reduced and operating ampacity of the underground distribution system can be increased. This paper presents the development and improvement of an intelligent cable monitoring system for the underground distribution power system, using DTS technology and OFCPCs as the underground distribution lines in the field.
15. On the Degradation Mechanism of Low-Voltage Underground Cable with Poly(Vinyl Chloride) Insulation
Tawancy, H. M.; Hassan, M.
2016-06-01
A study has been undertaken to determine the degradation mechanism leading to localized short-circuit failures of an underground low-voltage cable with PVC insulation. It is shown that that the insulation of outer sheath and conductor cores has been cracked by thermal degradation involving dehydrochlorination, oxidation, and loss of plasticizers leading to current leakage between the cores. Most evidence points out that overheating due to poor connection of copper wires as well as a chemically active soil has caused the observed degradation.
16. Full Scale Test on a 100km, 150kV AC Cable
Faria da Silva, Filipe Farria; Wiechowski, W.; Bak, Claus Leth; Gudmundsdottir, Unnur Stella
2010-01-01
This paper presents some of the results obtained from the electrical measurements on a 99.7 km, 150 kV three-phase AC cable, connecting 215 MW offshore wind farm Horns Rev 2, located in Denmark west coast, to Denmark's 400 kV transmission network. The measurements were performed at nominal voltag...
17. Theory of AC Loss in Cables with 2G HTS Wire
Clem, J.R.; Malozemoff, A.P.
2009-09-13
While considerable work has been done to understand AC losses in power cables made of first generation (1G) high temperature superconductor (HTS) wires, use of second generation (2G) HTS wires brings in some new considerations. The high critical current density of the HTS layer 2G wire reduces the surface superconductor hysteretic losses. Instead, gap and polygonal losses, flux transfer losses in imbalanced two layer cables and ferromagnetic losses for wires with NiW substrates constitute the principal contributions. Current imbalance and losses associated with the magnetic substrate can be minimized by orienting the substrates of the inner winding inward and the outer winding outward.
18. Magnetic fields and childhood cancer: an epidemiological investigation of the effects of high-voltage underground cables.
Bunch, K J; Swanson, J; Vincent, T J; Murphy, M F G
2015-09-01
Epidemiological evidence of increased risks for childhood leukaemia from magnetic fields has implicated, as one source of such fields, high-voltage overhead lines. Magnetic fields are not the only factor that varies in their vicinity, complicating interpretation of any associations. Underground cables (UGCs), however, produce magnetic fields but have no other discernible effects in their vicinity. We report here the largest ever epidemiological study of high voltage UGCs, based on 52,525 cases occurring from 1962-2008, with matched birth controls. We calculated the distance of the mother's address at child's birth to the closest 275 or 400 kV ac or high-voltage dc UGC in England and Wales and the resulting magnetic fields. Few people are exposed to magnetic fields from UGCs limiting the statistical power. We found no indications of an association of risk with distance or of trend in risk with increasing magnetic field for leukaemia, and no convincing pattern of risks for any other cancer. Trend estimates for leukaemia as shown by the odds ratio (and 95% confidence interval) per unit increase in exposure were: reciprocal of distance 0.99 (0.95-1.03), magnetic field 1.01 (0.76-1.33). The absence of risk detected in relation to UGCs tends to add to the argument that any risks from overhead lines may not be caused by magnetic fields. PMID:26344172
19. New piercing for insulated cables in underground networks; Novos conectores compactos perfurantes ('piercings') para cabos isoldados em redes subterraneas
Moreno, Fernando; Corral, Horacio [Tradis, SP (Brazil). E-mail: [email protected]
1999-07-01
This work presents a tap and transition connection in low voltage protected underground cables. This connection allows tapping for clients or branchings from a main energized cables. The compact connectors range various types of insulated cables protected and under grounded in a simple way. The work analysed the advantages of using two components polyurethane resins for the tapping protection and insulation restoring.
20. Experimental study of thermal field deriving from an underground electrical power cable buried in non-homogeneous soils
The electrical cables ampacity mainly depends on the cable system operation temperature. To achieve a better cable utilization and reduce the conservativeness typically employed in buried cable design, an accurate evaluation of the heat dissipation through the cables and the surrounding soil is important. In the traditional method adopted by the International Electrotechnical Commission (IEC) and the Institute of Electrical and Electronics Engineers (IEEE) for the computation of the thermal resistance between an existing underground cable system and the external environment, it is still assumed that the soil is homogeneous and has uniform thermal conductivity. Numerical studies have been conducted to predict the temperature distribution around the cable for various configurations and thermal properties of the soil. The paper presents an experimental study conducted on a scale model to investigate the heat transfer of a buried cable, with different geometrical configurations and thermal properties of the soil, and to validate a simplified model proposed by the authors in 2012 for the calculation of the thermal resistance between the underground pipe or electrical cable and the ground surface, in cases where the filling of the trench is filled with layers of materials with different thermal properties. Results show that experimental data are in good agreement with the numerical ones. -- Highlights: • Heat transfer of a buried cable has been experimentally studied on a scale model. • Different configurations and thermal properties of the soil have been tested. • Authors previously proposed a simplified model and obtained numerical results. • Experimental results and numerical ones previously obtained were in accordance
1. Numerical simulation of coupled heat, liquid water and water vapor in soils for heat dissipation of underground electrical power cables
The trend towards renewable energy comes along with a more and more decentralized production of electric energy. As a consequence many countries will have to build hundreds or even thousands of miles of underground transmission lines during the next years. The lifetime of a transmission line system strongly depends on its temperature. Therefore an accurate calculation of the cable temperature is essential for estimating and optimizing the system's lifetime. The International Electrotechnical Commission and the Institute of Electronics and Electrical Engineers are still employing classic approaches, dating back from the 1950s, that are missing fundamental phenomena involved in heat transport in soils. In recent years several authors [4,37] pointed out that for a proper computation of heat transport in soils, physical processes describing heat, liquid water and vapor transport must be coupled and the respective environmental weather conditions need to be considered. In this study we present a numerical model of coupled liquid water, vapor and heat flow, to describe heat dissipation from underground cables. At first the model is tested and validated on a downscaled experiment [32], secondly the model is applied on a simplified system to demonstrate the strong relation of the cable temperature on soil water content and finally the model is applied using real weather conditions to demonstrate that small changes in the design of underground transmission line systems can lead to considerable improvements in both average as well as peak-to-peak temperatures. - Highlights: • Wind farms and heat dissipation in underground power cables. • Cable lifetime, cable temperature and properties of surrounding soil. • Coupled model for heat dissipation, liquid water and vapor transport in soils. • Numerical simulation under real weather conditions. • Cable temperature depending on construction of transmission line system
2. AC loss performance of cable-in-conduit conductor. Influence of cable mechanical property on coupling loss reduction
The ITER Central Solenoid (CS) model coil, CS Insert and Nb3Al Insert were developed and tested from 2000 to 2002. The AC loss performances of these coils were investigated in various experiments. In addition, the AC losses of the CS and Nb3Al Insert conductors were measured using short CS and Nb3Al Insert conductors before the coil tests. The coupling time constants of these conductors were estimated to be 30 and 120 ms, respectively. On the other hand, the test results of the CS and Nb3Al Inserts show that the coupling currents induced in these conductors had multiple decay time constants. In fact, the existence of the coupling currents with long decay time constants, the order of which was in the thousands of seconds, was directly observed with hall sensors and voltage taps. Moreover, the AC loss test results show that electromagnetic force decreases coupling losses with exponential decay constants. This is because the weak sinter among the strands, which originated during heat treatment, was broken due to the electromagnetic force, and then the contact resistance among strands increased. It was found that this exponential decay constant was the function of a gap (i.e., a mechanical property of the cable) created between the cable and conduit due to electromagnetic force. The gap can be estimated by pressure drop, measured under the electromagnetic force. The pressure drop can easily be measured at an initial trial charge, and then it is possible to estimate the exponential decay constant before normal coil operation. Accordingly, it is possible to predict promptly how many times the trial operations are necessary to decrease the coupling losses to the designed value by measuring the coupling losses and the pressure drop during the initial coil operation trial. (author)
3. Earth return path impedances of underground cable for three-layer earth
B. HEMMATIAN; B. VAHIDI; S. H. HOSSEINIAN
2009-01-01
One of the factors that affect the parameters of an underground cable is earth return path impedance. Pollaczek developed a formula for the case of one-layer (homogenous) earth. But in practice the earth is composed of several layers. In this study we develop a new formula for earth return path impedance in the case of a three-layer earth. To check the accuracy of the obtained results, a comparison has been made with the finite element method (FEM). A comparison between the results of the Poilaczek formula and results of the obtained formula for a three-layer earth has been made, showing that the use of the Pollaczek formula instead of the actual formula can cause serious errors.
4. Interstrand and AC-loss measurements on Rutherford-type cables for accelerator magnet applications
Otmani, R; Tixador, P
2001-01-01
One of the main issues for particle accelerator magnets is the control of interstrand resistances. Too low resistances result in large coupling currents during ramping, which distort field quality, while too large resistances may prevent current redistribution among cable strands, resulting in degraded quench performance. In this paper, we review a series of interstrand resistance and AC-loss measurements performed on four Rutherford-type cables. The four cables have the same number of strands and similar outer dimensions, corresponding to LHC quadrupole cable specifications. The first cable is made from NbTi strands, coated with silver-tin alloy, the second one is made from bare Nb/sub 3/Sn strands, the third one is made also from bare Nb/sub 3/Sn strands but includes a 25- mu m-thick stainless steel core between the strand layers, and the last one is made from Nb/sub 3/Sn strands plated with chromium. To cross-check the two measurement types and assess their consistency, we compare the coupling-current time...
5. External electromagnetic transient sources: analysis of its effect in underground power cables; Fuentes transitorias electromagneticas externas: analisis de su efecto en los cables de potencia subterraneos
Escamilla Paz, Antonio
2009-07-01
In most of the electrical power systems that operate at present, the subterranean cables are only a complement. The cost of these cables is generally higher than the one of the aerial power lines, thus its use is restricted only to those areas where the construction of the aerial power lines is not feasible. It is estimated that for voltages lower than 110 kV this cost is up to seven times greater than the one of an aerial power line and for voltages higher than 380 kV it can be up to twenty times greater. Nevertheless, important reasons exist to construct a subterranean cable system such as: a) the fast growth of the urban centers and the industrial zones, which brings about restrictions of the rights of way for the construction of aerial power lines, b) the crossing of large water bodies, c) the congestion of aerial power lines near the generating substations or power plants, d) the crossing of air lines and e) the laws and the regulations, to mention some of them. The importance of the underground transmission systems of high and extra high voltage will be increased in the medium and the long term, therefore, it is considered that the effects of the external phenomena in these systems, like the inductions produced by the electromagnetic transient sources, will be more severe. In this research work the atmospheric discharges are defined as the external electromagnetic transient sources. The large dimension cables such as the power cables, behave as large collectors of the interferences produced by the atmospheric discharges, which can bring about damages in the components of a system. In order to avoid the damages and to increase the reliability of the subterranean cable systems it is necessary to use protective devices and appropriate insulation levels, mainly. If the phenomenon and the behavior of the system are properly represented, it is possible to more accurately determine the characteristics that the equipment must have to resist the over voltages and the
6. Theory of ac loss in power transmission cables with second generation high temperature superconductor wires
While a considerable amount of work has been done in an effort to understand ac losses in power transmission cables made of first generation high temperature superconductor (HTS) wires, use of second generation (2G) HTS wires brings in some new considerations. The high critical current density of the HTS layer in 2G wires reduces the surface superconductor hysteretic losses, for which a new formula is derived. Instead, gap and polygonal losses, flux transfer losses in imbalanced two-layer cables and ferromagnetic losses for wires with NiW substrates constitute the principal contributions. A formula for the flux transfer losses is also derived with a paramagnetic approximation for the substrate. Current imbalance and losses associated with the magnetic substrate can be minimized by orienting the substrates of the inner winding inward and the outer winding outward.
7. Quantification of the heat dissipation of underground medium and low-voltage cables; Quantifizierung der Waermeableitung bei erdverlegten Mittel- und Niederspannungskabeln
Stegner, Johannes; Drefke, Christof; Sass, Ingo [Technische Univ. Darmstadt (Germany). Inst. fuer Angewandte Geowissenschaften; Hentschel, Klaus [E.ON Bayern AG, Regensburg (Germany)
2013-06-01
The performance of underground power cables depends on its operational warming. In a research project, the influence of soil and bedding materials on this performance is investigated in consideration of climate, weather and water balance of the site.
8. Measuring ac losses in superconducting cables using a resonant circuit:Resonant current experiment (RESCUE)
Däumling, Manfred; Olsen, Søren Krüger; Rasmussen, Carsten;
1998-01-01
A simple way to obtain true ac losses with a resonant circuit containing a superconductor, using the decay of the circuit current, is described. For the measurement a capacitor is short circuited with a superconducting cable. Energy in the circuit is provided by either charging up the capacitors...... with a certain voltage, or letting a de flow in the superconductor. When the oscillations are started-either by opening a switch in case a de is flowing or by closing a switch to connect the charged capacitors with the superconductor-the current (via a Rogowski coil) or the voltage on the capacitor can...
9. Double Layered Sheath in Accurate HV XLPE Cable Modeling
Gudmundsdottir, Unnur Stella; Silva, J. De; Bak, Claus Leth;
2010-01-01
This paper discusses modelling of high voltage AC underground cables. For long cables, when crossbonding points are present, not only the coaxial mode of propagation is excited during transient phenomena, but also the intersheath mode. This causes inaccurate simulation results for high frequency...
10. Identification of problems when using long high voltage AC cable in transmission system I: Switching transient problems
Rahimi, Saeed; Wiechowski, W.; Randrup, M;
2008-01-01
the proper substitution and solution which make the transmission expansion possible with minimized visual impacts on the communities. Within European countries, Denmark was been at the forefront of replacing the transmission lines with cables. The project was supplying the power to the greater......Due to political and environmental pressures from the public and government side, upgrading and building new transmission facilities are becoming more and more difficult and in some cases the expansion of overhead transmission lines are impossible. This means that underground cable technology is...
11. Power applications for superconducting cables in Denmark
Tønnesen, Ole; Østergaard, Jacob; Olsen, S. Krüger
1999-01-01
In Denmark a growing concern for environmental protection has lead to wishes that the open country is kept free of overhead lines as far as possible. New lines under 100 kV and existing 60/50 kV lines should be established as underground cables. Superconducting cables represent an interesting...... alternative to conventional cables, as they are able to transmit two or more times the energy than a conventional cable. HTS cables with a room temperature dielectric design are especially interesting as a target for replacing overhead lines. Superconducting cables in the overall network are of interest in...... cases such as transmission of energy into cities and through areas of special interest. The planned large groups of windmills in Denmark generating up to 2000 MVA or more both on dry land and off-shore will be an obvious case for the application of superconducting AC or DC cables. These opportunities...
12. Techniques and equipment for detecting and locating incipient faults in underground power transmission cable systems. First technical progress report, 21 August 1978-31 March 1979
Phillips, A.C.; Nanevicz, J.E.; Adamo, R.C.; Cole, C.A.; Honey, S.K.; Petro, J.P.
1979-05-01
This work is to provide practical methods for detecting and locating incipient faults in energized and deenergized underground power transmission cable systems. Radio-frequency probing techniques are emphasized. Supporting tasks include measurements of cable characteristics at manufacturing plants and utility installations, field evaluation, development of signal couplers to access transmission lines, and a study of methods leading to technically effective and economical use of incipient-fault locators.
13. Numerical simulation of heat dissipation processes in underground power cable system situated in thermal backfill and buried in a multilayered soil
Highlights: • A practical thermal analysis of underground power cable system. • The geological measurements were performed for cable line placement location. • Dry zone formation effect included in soil and FTB thermal conductivity formula. • A simplified FEM model of underground power cable system. • The computational numerical code validation with ANSYS. - Abstract: This paper presents the thermal analysis of the underground transmission line, planned to be installed in one of the Polish power plants. The computations are performed by using the Finite Element Method (FEM) code, developed by the authors. The paper considers a system of three power cables arranged in flat (in-line) formation. The cable line is buried in the multilayered soil. The soil layers characteristic and thermal properties are determined from geological measurements. Different conditions of cable bedding are analyzed including power cables placement in the FTB or direct burial in a mother ground. The cable line burial depth, measured from the ground level, varies from 1 m to 2.5 m. Additionally, to include the effect of dry zones formation on the temperature distribution in cable line and surroundings, soil and FTB thermal conductivities are considered as a temperature-dependent. The proposed approach for determining the temperature-dependent thermal conductivity of soil layers is discussed in detail. The FEM simulation results are also compared with the results of the simulation that consider soil layers as homogeneous materials. Therefore, thermal conductivity is assumed to be constant for each layer. The results obtained by using the FEM code, developed by the authors, are compared with the results of ANSYS simulations, and a good agreement was found
14. Failure evaluation of underground high voltage cables (115 kV) in Mazatlan, Sinaloa: Microscopic method
Valero-Huerta, M.A.; Ramirez-Delgado, R. [Lab. de Pruebas de Equipos y Materiales, Irapuato (Mexico)
1995-11-01
The present paper is a complete analysis of the failure which occurred to the 115 kV power cable installed between the Mazatlan Centro and Mazatlan Norte Substations. Laboratory analysis that established the causes of the failure are included. It was concluded that the failure of the cable was provoked by the entrance of sewage water to the screen, and due to the presence of anaerobic organisms, resulted in the formation of sulfidic acid, which caused the severe corrosion that can be observed in the screen. The resulting loss of conductivity provoked heating capable of melting the isolator until its rupture.
15. Ac loss modelling and measurement of superconducting transformers with coated-conductor Roebel-cable in low-voltage winding
Pardo, Enric; Staines, Mike; Jiang, Zhenan; Glasson, Neil
2015-11-01
Power transformers using a high temperature superconductor (HTS) ReBCO coated conductor and liquid nitrogen dielectric have many potential advantages over conventional transformers. The ac loss in the windings complicates the cryogenics and reduces the efficiency, and hence it needs to be predicted in its design, usually by numerical calculations. This article presents detailed modelling of superconducting transformers with Roebel cable in the low-voltage (LV) winding and a high-voltage (HV) winding with more than 1000 turns. First, we model a 1 MVA 11 kV/415 V 3-phase transformer. The Roebel cable solenoid forming the LV winding is also analyzed as a stand-alone coil. Agreement between calculations and experiments of the 1 MVA transformer supports the model validity for a larger tentative 40 MVA 110 kV/11 kV 3-phase transformer design. We found that the ac loss in each winding is much lower when it is inserted in the transformer than as a stand-alone coil. The ac loss in the 1 and 40 MVA transformers is dominated by the LV and HV windings, respectively. Finally, the ratio of total loss over rated power of the 40 MVA transformer is reduced below 40% of that of the 1 MVA transformer. In conclusion, the modelling tool in this work can reliably predict the ac loss in real power applications.
16. Modelling of long High Voltage AC Cables in the Transmission System
Gudmundsdottir, Unnur Stella
for comparison at the measuring site. Measurements are performed on a 400 kV 7.6 km long cable, which is a part of a hybrid OHL/cable transmission line. The cables are laid in flat formation and have been in operation for several years. For performing the measurements, the cables are disconnected from...... time. From analysing the modal currents, the source of deviation is identified. The same phenomena and source for deviation between field measurements and simulation results is identified for a 400 kV flat formation crossbonded 7.6 km cable line, a 150 kV tight trefoil crossbonded 2.5 km cable line and...... a way, that the impedance matrix is no longer calculated from the analytical equations but from a finite element method including the proximity effect. A MATLAB program is constructed in order to calculate the impedance matrix based on the finite element method. Furthermore, this MATLAB program also...
17. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems
Sztykiel, Michal; Bak, Claus Leth; Wiechowski, Wojciech;
2010-01-01
Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay mode......-simulated and real world generated current signals connected to the relay.......Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay models...... can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP...
18. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems
Sztykiel, Michal; Bak, Claus Leth; Dollerup, Sebastian
2011-01-01
Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay......-simulated and real world generated current signals connected to the relay.......Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay...... models can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP...
19. Condition assessment of power cables using partial discharge diagnosis at damped AC voltages
Wester, F.J.
2004-01-01
The thesis focuses on the condition assessment of the distribution power cables, which have a very critical part in the distribution of electrical power over regional distances. The majority of the outages in the power system is related to the distribution cables, of which for more than 60% to internal defects. The material degradation in the power cables can be categorised into four local degradation processes, which are related to partial discharges. Partial discharge characteristics theref...
20. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems
Sztykiel, Michal; Bak, Claus Leth; Dollerup, Sebastian
2011-01-01
Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a detailed approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay models can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIP...
1. A nontrivial factor in determining current distribution in an ac HTS cable-proximity effect
2010-01-01
A superconductor has zero resistance at the superconducting state. This unique property creates many exceptional phenomena, of which some are known and the others are not. Our experiments with multilayer high temperature superconductor (HTS) cable samples revealed a new phenomenon that alternating current had a tendency to flow in the inner and outer layers of the cables. We attribute the cause of this phenomenon to the electromagnetic interaction in an infinite electrical conductivity medium and term it "super-proximity-effect". This effect will greatly affect the performance of a multilayer superconducting cable and other superconducting devices which are involved with alternating current transportation.
2. An EMC Evaluation of the Use of Unshielded Motor Cables in AC Adjustable Speed Drive Applications
Hanigovszki, Norbert; Poulsen, J.; Spiazzi, G.;
2004-01-01
-phase applications the occurrence of common-mode voltage is inherent due to asymmetrical output pulses. As a result, for electromagnetic compatibility (EMC) reasons, in most applications shielded cables are used between the inverter and the motor, implying high installation costs. The present paper discusses the use...... of cheaper, unshielded cables. A new method for measuring electromagnetic interference (EMI) from unshielded cables is proposed and measurement results are presented. The level of EMI is evaluated in different situations: without an output filter, with a classical LC output filter and with an...
3. Development of buried cable location survey system by underground rader for power distribution cables under pavements. Haiden chichuka no tame no chika radar ni yoru maisetsukan tansa system no kaihatsu
Suzuki, K.; Kitano, K.
1990-06-01
To execute construction work for power distribution cables under pavements reasonably, it is important to develop a technology capable of non-destructive detection of the location of existing buried cables from the ground surface. This study is to clarify the principle, measurement method, effectiveness, and limitation of the underground radar system which is at present considered as the most effective survey method for buried cables. In this system, accuracy in measuring the depth of underground cable location by a separated type antenna has been improved, software to improve resolution by a migration process has been developed, and a compact survey system which can analyze the data on the site has been realized. As aresult of the survey at city areas, all pipes buried less than 1m in depth with the resistivity value of more than 100 {Omega} m were detected as well as those less than 2m in depth with more than some 100 {Omega} m. However, non-metal pipes buried deeper than 1m in the ground of less than 100 {Omega} m were not detected. Consequently, improvement of the system is necessary in future. 7 refs., 23 figs., 6 tabs.
4. UNDERGROUND
Full text: Cossetted deep underground, sheltered from cosmic ray noise, has always been a favourite haunt of neutrino physicists. Already in the 1930s, significant limits were obtained by taking a geiger counter down in Holborn 'tube' station, one of the deepest in London's underground system. Since then, neutrino physicists have popped up in many unlikely places - gold mines, salt mines, and road tunnels deep under mountain chains. Two such locations - the 1MB (Irvine/ Michigan/Brookhaven) detector 600 metres below ground in an Ohio salt mine, and the Kamiokande apparatus 1000m underground 300 km west of Tokyo - picked up neutrinos on 23 February 1987 from the famous 1987A supernova. Purpose-built underground laboratories have made life easier, notably the Italian Gran Sasso Laboratory near Rome, 1.4 kilometres below the surface, and the Russian Baksan Neutrino Observatory under Mount Andyrchi in the Caucasus range. Gran Sasso houses ICARUS (April, page 15), Gallex, Borexino, Macro and the LVD Large Volume Detector, while Baksan is the home of the SAGE gallium-based solar neutrino experiment. Elsewhere, important ongoing underground neutrino experiments include Soudan II in the US (April, page 16), the Canadian Sudbury Neutrino Observatory with its heavy water target (January 1990, page 23), and Superkamiokande in Japan (May 1991, page 8)
5. Optimal Selection of AC Cables for Large Scale Offshore Wind Farms
Hou, Peng; Hu, Weihao; Chen, Zhe
2014-01-01
platform in Matlab. A real offshore wind farm is chosen as the study case to demonstrate the proposed method. Furthermore, the optimization is also applied to an offshore wind farm under development. It can be observed from the results that the proposed optimal cable selection framework is an efficient and...
6. Tunnel Boring Machine Cutter Maintenance for Constructing Underground Cable Lines from Nuclear Power Plants
The tunnel boring machine (TBM) can construct an underground tunnel efficiently and without construction noise vibration related problems. Many civil projects, such as NPP construction, set importance on the economics of construction. Thus, advance rate, which is the speed at which the TBM is able to progress along its intended route, is one of the key factors affecting construction period and construction expenses. As the saying goes, time is money. Right Double Quotation Mark In addition, it is important to manage construction permits and civil complaints, even when construction expenses and construction periods are excluded. So, accurate prediction for advance rate is important when designing tunnel project. Several designers and project owners have tried to improve construction efficiency and tunneling advance rate.. There have been several studies on managing the rate of wear, designing an optimum tunnel face, and finding the optimum cutter spacing. Cutter replacements due to cutter wear and tear are very important because the wear and tear of cutters attached to the cutter head profoundly affect the advance rate. To manage cutter wear and tear is to control parameters related to cutter shape and cutter wear rate. There have been studies on the relationship between rock properties or TBM characteristics, and cutter wear or replacement. However, many of these studies relied on computer simulations or other small scale experiments. Therefore, this paper attempts to present a correlation between cutter replacement or cutter wear, against various parameters using practical data such as rock quality and TBM shield specifications, from an actual construction site. This study was conducted to suggest directions in the improvement of TBM cutters by analyzing relationships between rock conditions and cutter maintenance as well as TBM advance rates. Actual field data was collected and compared to actual design values in evaluating the effectiveness of traditional
7. Tunnel Boring Machine Cutter Maintenance for Constructing Underground Cable Lines from Nuclear Power Plants
Lee, Jae Wang; Yee, Eric [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)
2014-10-15
The tunnel boring machine (TBM) can construct an underground tunnel efficiently and without construction noise vibration related problems. Many civil projects, such as NPP construction, set importance on the economics of construction. Thus, advance rate, which is the speed at which the TBM is able to progress along its intended route, is one of the key factors affecting construction period and construction expenses. As the saying goes, time is money. Right Double Quotation Mark In addition, it is important to manage construction permits and civil complaints, even when construction expenses and construction periods are excluded. So, accurate prediction for advance rate is important when designing tunnel project. Several designers and project owners have tried to improve construction efficiency and tunneling advance rate.. There have been several studies on managing the rate of wear, designing an optimum tunnel face, and finding the optimum cutter spacing. Cutter replacements due to cutter wear and tear are very important because the wear and tear of cutters attached to the cutter head profoundly affect the advance rate. To manage cutter wear and tear is to control parameters related to cutter shape and cutter wear rate. There have been studies on the relationship between rock properties or TBM characteristics, and cutter wear or replacement. However, many of these studies relied on computer simulations or other small scale experiments. Therefore, this paper attempts to present a correlation between cutter replacement or cutter wear, against various parameters using practical data such as rock quality and TBM shield specifications, from an actual construction site. This study was conducted to suggest directions in the improvement of TBM cutters by analyzing relationships between rock conditions and cutter maintenance as well as TBM advance rates. Actual field data was collected and compared to actual design values in evaluating the effectiveness of traditional
8. AC loss in high-temperature superconducting conductors, cables and windings for power devices
High-temperature superconducting (HTS) transformers and reactor coils promise decreased weight and volume and higher efficiency. A critical design parameter for such devices is the AC loss in the conductor. The state of the art for AC-loss reduction in HTS power devices is described, starting from the loss in the single HTS tape. Improved tape manufacturing techniques have led to a significant decrease in the magnetization loss. Transport-current loss is decreased by choosing the right operating current and temperature. The role of tape dimensions, filament twist and resistive matrix is discussed and a comparison is made between state-of-the-art BSCCO and YBCO tapes. In transformer and reactor coils the AC loss in the tape is influenced by adjacent tapes in the coil, fields from other coils, overcurrents and higher harmonics. These factors are accounted for by a new AC-loss prediction model. Field components perpendicular to the tape are minimized by optimizing the coil design and by flux guidance pieces. High-current windings are made of Roebel conductors with transposed tapes. The model iteratively finds the temperature distribution in the winding and predicts the onset of thermal instability. We have fabricated and tested several AC windings and used them to validate the model. Now we can confidently use the model as an engineering tool for designing HTS windings and for determining the necessary tape properties
9. Water treeing in underground power cables: modelling of the trees and calculation of the electric field perturbation
Acedo García, Miguel; Radu, I.; Frutos Rayego, Fabián; Filippini, Jean César; Notingher, P.
2001-01-01
In order to explain the development of different types of water trees and the related dielectric breakdowns in extruded power cables, it is necessary to analyse the dielectric properties of the corresponding treed regions and their influence on the distribution of electric field. The study presented in this paper is both experimental and theoretical. Experimentally, we performed the laboratory ageing of a power cable for accelerated conditions of applied voltage and frequency: ...
10. Power System Technical Performance Issues Related to the Application of Long HVAC Cables
Bak, Claus Leth
The aim of this TB is to serve as a practical guide for preparing models and performing studies necessary during the assessment of the technical performance of HV/EHV systems with a large share of (long) AC cables. The brochure follows all phases of planning and analysis of a typical underground...
11. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems, EMTDC/PSCAD Relays Modelling
Bak, Claus Leth; Sztykiel, Michal; Dollerup, Sebastian
2011-01-01
Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows creating complex and accurate relay models derived from the original algorithms. Relay model......-simulated and real world generated current signals connected to the relay.......Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows creating complex and accurate relay models derived from the original algorithms. Relay models...... can be applied with various systems, allowing obtaining the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC 4 7SD522/610. Relay model was verified experimentally with its real equivalent by both EMTP...
12. Line Differential Protection Scheme Modelling for Underground 420 kV Cable Systems:EMTDC/PSCAD Relays Modelling
Sztykiel, Michal; Bak, Claus Leth; Wiechowski, Wojciech; Dollerup, Sebastian
2010-01-01
Based on the analysis of a specific relay model and an HVAC (High Voltage Alternating Current) cable system, a new approach to EMTDC/PSCAD modelling of protective relays is presented. Such approach allows to create complex and accurate relay models derived from the original algorithms. Relay models can be applied with various systems, allowing to obtain the most optimal configuration of the protective relaying. The present paper describes modelling methodology on the basis of Siemens SIPROTEC...
13. A flexible super conducting ac cable: radial thermal contraction and the x-ray examination of a sample length of cold core
The temperature reduction which a superconducting cable core will have to undergo following its manufacture and installation is nearly 300 K before it can be used. The satisfactory accommodation of the corresponding significant amount of thermal contraction of its component parts is therefore of major importance. This paper is concerned with such thermal contraction upon cooling of a flexible superconducting ac cable core comprising helically laid strip conductors of niobium clad copper and a polyethylene tape dielectric with electrostatic screens and bedding layers. A method is described of designing, for a controlled amount of radial contraction, a core held at near constant length. A report is also given of the x-ray examination of a sample core used for voltage tests. The relevance of the results to some other designs of core is discussed. (author)
14. Design procedure and operation experience of data acquisition and control system for 22.9 kV underground HTS power cable
Ryoo, H. S.; Sohn, S. H.; Hwang, S. D.; Lim, J. H.; Choi, H. S.; Yatsuka, K.; Masuda, T.; Isojima, S.; Watanabe, M.; Suzawa, C.; Koo, J. Y.
2007-10-01
A new 100 m underground HTS cable system was planned for an experimental study in a real scale. The main targets of the project were the verification of the system application. Various types and multipoint analogue data including digital control sequence data were required to be measured. Because of the long operating period of the system cooling and warming sequence, very high operating stability was required. Additionally the economically designed main cooling facility was requested over-night manual operation. The basic function of the data acquisition and control system was the gathering of various type data and the control of test facilities include the cooling facility. Most effort of the design procedure was focused on making the automatic operation including under an emergency situation and the alerting of the emergency state to the operators staying even remote place. The main focus of this function was reducing of the operating man power, specially requested for over-night. So various emergency situations and scenarios were considered and analyzed for the automation operation.
15. A two-dimensional finite element method to calculate the AC loss in superconducting cables, wires and coated conductors
In order to utilize HTS conductors in AC electrical devices, it is very important to be able to understand the characteristics of HTS materials in the AC electromagnetic conditions and give an accurate estimate of the AC loss. A numerical method is proposed in this paper to estimate the AC loss in superconducting conductors including MgB2 wires and YBCO coated conductors. This method is based on solving a set of partial differential equations in which the magnetic field is used as the state variable to get the current and electric field distributions in the cross sections of the conductors and hence the AC loss can be calculated. This method is used to model a single-element and a multi-element MgB2 wires. The results demonstrate that the multi-element MgB2 wire has a lower AC loss than a single-element one when carrying the same current. The model is also used to simulate YBCO coated conductors by simplifying the superconducting thin tape into a one-dimensional region where the thickness of the coated conductor can be ignored. The results show a good agreement with the measurement
16. A two-dimensional finite element method to calculate the AC loss in superconducting cables, wires and coated conductors
Hong, Z; Jiang, Y; Pei, R; Coombs, T A [Electronic, Power and Energy Conversion Group, Engineering Department, University of Cambridge, CB2 1PZ (United Kingdom); Ye, L [Department of Electrical Power Engineering, CAU, P. O. Box 210, Beijing 100083 (China); Campbell, A M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, CB3 0HE (United Kingdom)], E-mail: [email protected]
2008-02-15
In order to utilize HTS conductors in AC electrical devices, it is very important to be able to understand the characteristics of HTS materials in the AC electromagnetic conditions and give an accurate estimate of the AC loss. A numerical method is proposed in this paper to estimate the AC loss in superconducting conductors including MgB{sub 2} wires and YBCO coated conductors. This method is based on solving a set of partial differential equations in which the magnetic field is used as the state variable to get the current and electric field distributions in the cross sections of the conductors and hence the AC loss can be calculated. This method is used to model a single-element and a multi-element MgB{sub 2} wires. The results demonstrate that the multi-element MgB{sub 2} wire has a lower AC loss than a single-element one when carrying the same current. The model is also used to simulate YBCO coated conductors by simplifying the superconducting thin tape into a one-dimensional region where the thickness of the coated conductor can be ignored. The results show a good agreement with the measurement.
17. Cable Diagnostic Focused Initiative
Hartlein, R.A.; Hampton, R.N.
2010-12-30
This report summarizes an extensive effort made to understand how to effectively use the various diagnostic technologies to establish the condition of medium voltage underground cable circuits. These circuits make up an extensive portion of the electric delivery infrastructure in the United States. Much of this infrastructure is old and experiencing unacceptable failure rates. By deploying efficient diagnostic testing programs, electric utilities can replace or repair circuits that are about to fail, providing an optimal approach to improving electric system reliability. This is an intrinsically complex topic. Underground cable systems are not homogeneous. Cable circuits often contain multiple branches with different cable designs and a range of insulation materials. In addition, each insulation material ages differently as a function of time, temperature and operating environment. To complicate matters further, there are a wide variety of diagnostic technologies available for assessing the condition of cable circuits with a diversity of claims about the effectiveness of each approach. As a result, the benefits of deploying cable diagnostic testing programs have been difficult to establish, leading many utilities to avoid the their use altogether. This project was designed to help address these issues. The information provided is the result of a collaborative effort between Georgia Tech NEETRAC staff, Georgia Tech academic faculty, electric utility industry participants, as well as cable system diagnostic testing service providers and test equipment providers. Report topics include: •How cable systems age and fail, •The various technologies available for detecting potential failure sites, •The advantages and disadvantages of different diagnostic technologies, •Different approaches for utilities to employ cable system diagnostics. The primary deliverables of this project are this report, a Cable Diagnostic Handbook (a subset of this report) and an online
18. Low Friction Cryostat for HTS Power Cable of Dutch Project
Chevtchenko, O.; Zuijderduin, R.; Smit, J.; Willen, D.; Lentge, H.; Thidemann, C.; Traeholt, C.
2012-01-01
Particulars of 6 km long HTS AC power cable for Amsterdam project are: a cable has to fit in an annulus of 160 mm, with only two cooling stations at the cable ends [1]. Application of existing solutions for HTS cables would result in excessively high coolant pressure drop in the cable, possibly affe
19. Effects of Formvar coating and copper-nickel outer sheath on the ac losses of multi-strand subsize cables
Ac losses of two subcables, one with Formvar coating on the strands of the BNL 12-ml NbTi/Cu/CuNi conductor and another without the coating, were measured using the ANL Subcable Test Facility. The results indicate that couplings among the strands with and without the Formvar coating were quite weak. Weak coupling of the bare strands is due to the high resistance of the copper-nickel outer sheath. In the regime of B(dot) = 0 approx. 1.2 T/s and B = 0 approx. 4 T, the magnetic diffusion time constant was (3.8 - 5.7) x 10-3 s
20. Switching Overvoltages in 60 kV reactor compensated cable grid due to resonance after disconnection
Bak, Claus Leth; Baldursson, Haukur; Oumarou, Abdoul M.
2008-01-01
Some electrical distribution companies are nowadays replacing overhead lines with underground cables. These changes from overhead to underground cable provoke an increased reactive power production in the grid. To save circuit breakers the reactors needed for compensating this excessive reactive ...
1. Techniques and equipment for detecting and locating incipient faults in underground power transmission cable systems. Technical progress report 3, 1 July 1979-30 September 1979
Phillips, A.C.; Nanevicz, J.E.; Adamo, R.C.; Cole, C.A.; Honey, S.K.; Petro, J.P.
1980-04-01
The study is divided into seven tasks: (1) developing RF sounding techniques including experimental detector/locator units such as the HV crossmodulation sounder; (2) constructing a prototype swept-frequency cable sounder; (3) measuring cable characteristics; (4) developing power-transmission-line signal couplers; (5) constructing an HV source to augment experimental and prototype detector/locator units; (6) evaluating the prototype swept-frequency cable sounder; and (7) studying technically effective and economical use of incipient-fault detector/locator units.
2. Underground pipeline corrosion
Orazem, Mark
2014-01-01
Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n
3. Electromagnetic transients in power cables
da Silva, Filipe Faria
2013-01-01
From the more basic concepts to the most advanced ones where long and laborious simulation models are required, Electromagnetic Transients in Power Cables provides a thorough insight into the study of electromagnetic transients and underground power cables. Explanations and demonstrations of different electromagnetic transient phenomena are provided, from simple lumped-parameter circuits to complex cable-based high voltage networks, as well as instructions on how to model the cables.Supported throughout by illustrations, circuit diagrams and simulation results, each chapter contains exercises,
4. Gjoea power cable; a green solution
Dretvik, Svein-Egil
2010-07-01
An alternative to today's power generation offshore using either gas or diesel, is alternating current (AC) electric power cable from shore. The power from shore through the AC cable gives high savings for the environment. The cable replaces 4 gas turbines with a total CO2 disposal of 240 00 tonnes each year which represents the disposal of 100 000 cars. ABB was awarded the contract which includes engineering, fabrication and installation of the power cable from Mongstad to the Gjoea platform which will be the longest AC cable in the world with a total length of 100 km. The presentation will include system design, qualification of dynamic power cable, cable fabrication experiences, testing at fabrication yard and installation aspects. (Author)
5. Strengthening future electricity grid of the Netherlands by integration of HTS transmission cables
The electricity grid of the Netherlands is changing. There is a call of society to use more underground cables, less overhead lines (OHL) and to reduce magnetic emissions. At the same time, parts of the future transmission grid need strengthening depending on the electricity demand in the coming decades [1]. Novel high temperature superconductor (HTS) AC transmission cables can play a role in strengthening the grid. The advantages as compared to alternatives, are: economic, underground, higher power capacity, lower losses, reduced magnetic field emissions in (existing) OHL, compact: less occupation of land and less permits needed, a possibility to keep 380 kV voltage level in the grid for as long as needed. The main obstacles are: the relatively high price of HTS tapes and insufficient maturity of the HTS cable technology. In the paper we focus on a 34 km long connection in the transmission grid (to be strengthened in three of the four of TenneT scenarios [1]), present the network study results, derive the requirements for corresponding HTS transmission cable system and compare HTS system to the alternatives (OHLs and XLPE cables).
6. Power applications for superconducting cables
Tønnesen, Ole; Hansen, Steen; Jørgensen, Preben; Lomholt, Karin; Mikkelsen, Søren D.; Okholm, Jan; Salvin, Sven; Østergaard, Jacob
2000-01-01
High temperature superconducting (HTS) cables for use in electric ac power systems are under development around the world today. There are two main constructions under development: the room temperature dielectric design and the cryogenic dielectric design. However, theoretical studies have shown...... that the insertion of these cables in the network is not without problems. The network stability requirements may impose severe constraints on the actual obtainable length of superconducting cables. Load flow considerations show that it may be difficult to use these high current cables to their full...
7. Techniques and equipment for detecting and locating incipient faults in underground power transmission cable systems. Technical progress report 2, 1 April 1979-30 June 1979
Phillips, A.C.; Naneviez, J.E.; Adamo, R.C.; Cole, C.A.; Honey, S.K.; Petro, J.P.
1980-01-01
The study has been divided into seven tasks: (1) development of RF probing techniques including experimental detector/locator units; (2) construction of a prototype detector/locator unit; (3) measurement of cable characteristics; (4) development of power-transmission-line signal couplers; (5) construction of a high-voltage (HV) source to augment experimental or prototype detector/locator units; (6) evaluation of the prototype detector/locator unit; and (7) study of technically effective and economical use of incipient-fault detector/locator units.
8. Cable manufacture
Gamble, P.
1972-01-01
A survey is presented of flat electrical cable manufacturing, with particular reference to patented processes. The economics of manufacture based on an analysis of material and operating costs is considered for the various methods. Attention is given to the competitive advantages of the several processes and their resulting products. The historical area of flat cable manufacture is presented to give a frame of reference for the survey.
9. Switching Restrikes in HVAC Cable Lines and Hybrid HVAC Cable/OHL Lines
da Silva, Filipe Miguel Faria; Bak, Claus Leth; Balle Holst, Per
2011-01-01
The disconnection of HV underground cables may, if unsuccessful, originate a restrike in the circuit breaker, leading to high overvoltages, and potentially damaging the cable and near equipment. Due to the cable high capacitance and low resistance the voltage damping is slow, resulting, half a...... cycle after the disconnection, in a voltage of approximately 2 pu at the circuit breaker terminals. In case of restrike in that instant, it is theoretical possible to attain an overvoltage of 3 pu. The overvoltage can be even larger in hybrid cable-Overhead Lines (OHL), due to voltage magnifications in...
10. Low Friction Cryostat for HTS Power Cable of Dutch Project
Chevtchenko, Oleg; Zuijderduin, Roy; Smit, Johan;
2012-01-01
affecting public acceptance of the project. In order to solve this problem, a model cryostat was developed consisting of alternating rigid and flexible sections and hydraulic tests were conducted using sub-cooled liquid nitrogen. In the 47 m-long cryostat, containing a full-size HTS cable model, measured......Particulars of 6km long HTS AC power cable for Amsterdam project are: a cable has to fit in an annulus of 160mm, with only two cooling stations at the cable ends [1]. Application of existing solutions for HTS cables would result in excessively high coolant pressure drop in the cable, possibly...
11. Superconducting power cables in Denmark - a case study
Østergaard, Jacob
1997-01-01
HTS cables will be less expensive for high power ratings, have lower losses for lines with a high load, and have a reduced reactive power production. The use of superconducting cables in Denmark accommodate plans by the Danish utility to make a substantial conversion of overhead lines to underground......A case study of a 450 MVA, 132 kV high temperature superconducting (HTS) power transmission cable has been carried out. In the study, a superconducting cable system is compared to a conventional cable system which is under construction for an actual transmission line in the Danish grid. The study...
12. Electrohydrodynamic pumping in cable pipes. Final report
Crowley, J.M.; Chato, J.C.
1983-02-01
Many oil-insulated electric power cables are limited by heat buildup caused in part by the low thermal conductivity of the oil. Circulation of the oil is known to reduce the cable temperature, but can lead to excessive pressure buildup on long cables when using conventional pumping methods. An alternate pumping method using distributed electric fields to avoid this pressure buildup is described. Electrohydrodynamic (EHD) pumping was studied both theoretically and experimentally for possible application in underground cable cooling. Theoretical studies included both analytical and finite-element analysis of the flow patterns driven by travelling electric fields. Experimentally, flow rates in a cable-pipe model were measured under a wide variety of operating conditions. Theory and experiment are in agreement for velocities below 10 cm/s, but higher velocities could not be reached in the experiment, due to increased electroconvection and, possibly, turbulence.
13. Cable Stability
Bottura, L
2014-01-01
Superconductor stability is at the core of the design of any successful cable and magnet application. This chapter reviews the initial understanding of the stability mechanism, and reviews matters of importance for stability such as the nature and magnitude of the perturbation spectrum and the cooling mechanisms. Various stability strategies are studied, providing criteria that depend on the desired design and operating conditions.
14. On stiffening cables of a long reach manipulator
A long reach manipulator will be used for waste remediation in large underground storage tanks. The manipulator's slenderness makes it flexible and difficult to control. A low-cost and effective method to enhance the manipulator's stiffness is proposed in this research by using suspension cables. These cables can also be used to accurately measure the position of the manipulator's wrist
15. Undergrounding issues
As part of a general review of British Columbia Hydro's rights-of-way policies, a task group was formed to explore and assess the technical, social, environmental, and economic issues related to the provision of suitable underground rights-of-way for distribution and transmission lines. Issues considered were: evaluations of undergrounding; designation of service areas as underground areas; the BC Hydro fund to assist municipalities in beautifying selected areas by placing existing overhead lines underground; community funding of undergrounding; underground options to transmission and distribution requirements; and long-range underground row planning. Key findings are as follows. Undergrounding is technically feasible and available for all BC Hydro operating voltages, but initial construction costs of undergrounding continue to exceed equivalent overhead by a significant margin. Undergrounding can contribute to the optimization of existing rights-of-way. Public safety is improved with undergrounding and long-term benefits to BC Hydro and society are provided by undergrounding, compared to overhead options. Customers have shown some willingness to contribute to the cost of undergrounding, and it is generally agreed that those communities that want undergrounding should pay for it. Policy recommendations are made under each of the issue areas, and justifications for the recommendations are given along with implementation costs and alternative options
16. Applying Diagnostics to Enhance Cable System Reliability (Cable Diagnostic Focused Initiative, Phase II)
Hartlein, Rick [Georgia Tech Research Corporation (GTRC), Atlanta, GA (United States). National Electric Energy Testing, Research and Applications Center (NEETRAC); Hampton, Nigel [Georgia Tech Research Corporation (GTRC), Atlanta, GA (United States). National Electric Energy Testing, Research and Applications Center (NEETRAC); Perkel, Josh [Georgia Tech Research Corporation (GTRC), Atlanta, GA (United States). National Electric Energy Testing, Research and Applications Center (NEETRAC); Hernandez, JC [Univ. de Los Andes, Merida (Venezuela); Elledge, Stacy [Georgia Tech Research Corporation (GTRC), Atlanta, GA (United States). National Electric Energy Testing, Research and Applications Center (NEETRAC); del Valle, Yamille [Georgia Tech Research Corporation (GTRC), Atlanta, GA (United States). National Electric Energy Testing, Research and Applications Center (NEETRAC); Grimaldo, Jose [Georgia Inst. of Technology, Atlanta, GA (United States). School of Electrical and Computer Engineering; Deku, Kodzo [Georgia Inst. of Technology, Atlanta, GA (United States). George W. Woodruff School of Mechanical Engineering
2016-02-01
The Cable Diagnostic Focused Initiative (CDFI) played a significant and powerful role in clarifying the concerns and understanding the benefits of performing diagnostic tests on underground power cable systems. This project focused on the medium and high voltage cable systems used in utility transmission and distribution (T&D) systems. While many of the analysis techniques and interpretations are applicable to diagnostics and cable systems outside of T&D, areas such as generating stations (nuclear, coal, wind, etc.) and other industrial environments were not the focus. Many large utilities in North America now deploy diagnostics or have changed their diagnostic testing approach as a result of this project. Previous to the CDFI, different diagnostic technology providers individually promoted their approach as the “the best” or “the only” means of detecting cable system defects.
17. 300 Area signal cable study
This report was prepared to discuss the alternatives available for removing the 300 Area overhead signal cable system. This system, installed in 1969, has been used for various monitoring and communication signaling needs throughout the 300 Area. Over the years this cabling system has deteriorated, has been continually reconfigured, and has been poorly documented to the point of nonreliability. The first step was to look at the systems utilizing the overhead signal cable that are still required for operation. Of the ten systems that once operated via the signal cable, only five are still required; the civil defense evacuation alarms, the public address (PA) system, the criticality alarms, the Pacific Northwest Laboratory Facilities Management Control System (FMCS), and the 384 annunciator panel. Of these five, the criticality alarms and the FMCS have been dealt with under other proposals. Therefore, this study focused on the alternatives available for the remaining three systems (evacuation alarms, PA system, and 384 panel) plus the accountability aid phones. Once the systems to be discussed were determined, then three alternatives for providing the signaling pathway were examined for each system: (1) re-wire using underground communication ducts, (2) use the Integrated Voice/Data Telecommunications System (IVDTS) already installed and operated by US West, and (3) use radio control. Each alternative was developed with an estimated cost, advantages, and disadvantages. Finally, a recommendation was provided for the best alternative for each system
18. Design and Evaluation of Ybco Cable for the Albany Hts Cable Project
Ohya, M.; Yumura, H.; Ashibe, Y.; Ito, H.; Masuda, T.; Sato, K.
2008-03-01
The Albany Cable Project's aim is to develop a 350 meter long HTS cable system with a capacity of 800 A at 34.5 kV, located between two substations in the National Grid Power Company's grid. In-grid use of BSCCO HTS cable began on July 20, 2006, and successful long-term operation proceeded as planned. The cable system consists of two cables, one 320 meters long and the other 30 meters, a cable-to-cable splice in a vault, two terminations, and a cooling system. In Phase-II of the Albany project, this autumn, the 30-meter section will be replaced with YBCO cable. The test manufacturing and evaluation of YBCO cable has been carried out using SuperPower's YBCO wires in order to confirm the credibility of the cable design. No degradation of the critical current was found at any stage of manufacture. The fault-current test, involving a 1-meter sample carrying 23 kA at 38 cycles, was conducted under open-bath conditions. The temperature increases at the conductor and shield were comparable to those of the BSCCO core, and no Ic degradation was found after the fault-current test. After the design suitability was confirmed, a 30-meter YBCO cable was manufactured. The critical current of the conductor and the shield were approximately 2.6 kA and 2.4 kA, respectively, almost the same as the design values, considering the wire's Ic and the effect of the magnetic field. The AC loss of the sample cable was 0.34 W/m/phase at 800 Arms and 60 Hz. Following favorable shipping test results, the YBCO cable was shipped to the United States, and arrived at the site in June 2007.
19. Research and Promotion on the Automatic Roll Line Device of Recycling Communication Cable on the Underground Coal Mine Working Face%煤矿井下工作面回收通讯电缆自动卷线装置的研发和推广
贾鸿飞
2015-01-01
随着科学技术的发展，煤矿的建设也发生了日新月异的变化，当代的现代化煤矿逐步开始进入到数字化矿井的阶段。数字化矿井综采工作面的无线通讯、视频的显示、各个综采设备的运行状态的数据，与地面中心站的网络相连接起来，能实时监视综采工作面的状态，达到了煤矿的安全生产。伴随而来的问题就是综采工作面在回采过程中将回收大量的通讯电缆，其中包括通讯光缆。本实用新型提供的煤矿井下工作面回收通讯电缆自动卷线装置，属于煤矿井下综采工作面设备技术领域，主要解决现有技术人工盘电缆存在着电缆凌乱、摆放不整齐、费时费力、效率低、降低采购成本等诸多问题。本文着重从煤矿井下工作面回收各类通讯电缆自动卷线装置的研发和推广方面进行了相关的阐述与分析。%With the development of science and technology, the construction of coal mine has also changed a lot, the contemporary modernization coal mine gradually begins to enter the stage of digital mine. The connection of wireless communications, video display, running status data of each fully mechanized equipment in the digital coal mine fully mechanized working face with network of the ground central station can achieve real-time monitoring of the state of fully mechanized working face and achieve the coal mine safety production. At the same time, the problems are associated that the fully mechanized working face will recycle a lot of communication cable including communication optical cable in the extraction process. This automatic volume line device of recycling communication cable in the underground coal mine working face provided by this utility model belongs to the equipment technology of underground coal mine fully mechanized working face. It mainly solves the messy cable and auf-stellen, time-consuming, low efficiency, reduce procurement costs and other
20. Universal Cable Brackets
Vanvalkenburgh, C.
1985-01-01
Concept allows routing easily changed. No custom hardware required in concept. Instead, standard brackets cut to length and installed at selected locations along cable route. If cable route is changed, brackets simply moved to new locations. Concept for "universal" cable brackets make it easy to route electrical cable around and through virtually any structure.
1. Switching Overvoltages in 60 kV reactor compensated cable grid due to resonance after disconnection
Bak, Claus Leth; Baldursson, Haukur; Oumarou, Abdoul M.
2008-01-01
Some electrical distribution companies are nowadays replacing overhead lines with underground cables. These changes from overhead to underground cable provoke an increased reactive power production in the grid. To save circuit breakers the reactors needed for compensating this excessive reactive...... power could be directly connected to long cables. Switching both cable and reactor together will cause resonance to occur between the cable capacitance and the inductance of the cable during last end disconnection. Similar type of resonance condition is known to have caused switching overvoltages on the...... 400kV grid in Denmark. Therefore it is considered necessary to analyze further whether connecting a reactor directly to 60kV cable can cause switching overvoltages. A model in PSCAD was used to analyze which parameters can cause overvoltage. The switching resonance overvoltage was found to be caused...
2. Conventional cable testing methods: strengths, weaknesses and possibilities
The paper reviews the major conventional methods that can be used to test power plant cables. It assesses their usefulness in diagnosing the condition of the insulation of the cable and then proposes some possible directions for innovation. The methods examined are dc insulation resistance measurement, ac signal injection for continuous monitoring and fault location, and the ac measurement of capacitance and loss angle. Specific subjects considered are the effects of temperature, cable construction and installation, and the validity of insulation resistance or loss angle measurement. The innovative proposals refer to the use of automation in the measurement and of computer-based Expert Systems for the evaluation of the results
3. Parametric study on coupling loss in subsize ITER Nb3Sn cabled specimen
Nijhuis, Arend; Kate, ten, F.J.W.; Bruzzone, Pierluigi; Bottura, Luca
1996-01-01
The cable in conduit conductors for the various ITER coils are required to function under pulse conditions and fields up to 13 T. A parametric study, restricted to a limited variation of the reference cable lay out, is carried out to clarify the quantitative impact of various cable parameters on the coupling loss and to find realistic values for the coupling loss time constants to be used in ac loss computations. The investigations cover ac coupling loss measurements on jacketed sub- and full...
4. Experimental Investigation of the Corona Discharge in Electrical Transmission due to AC/DC Electric Fields
Fuangpian Phanupong
2016-01-01
Full Text Available Nowadays, using of High Voltage Direct Current (HVDC transmission to maximize the transmission efficiency, bulk power transmission, connection of renewable power source from wind farm to the grid is of prime concern for the utility. However, due to the high electric field stress from Direct Current (DC line, the corona discharge can easily be occurred at the conductor surface leading to transmission loss. Therefore, the polarity effect of DC lines on corona inception and breakdown voltage should be investigated. In this work, the effect of DC polarity and Alternating Current (AC field stress on corona inception voltage and corona discharge is investigated on various test objects, such as High Voltage (HV needle, needle at ground plane, internal defect, surface discharge, underground cable without cable termination, cable termination with simulated defect and bare overhead conductor. The corona discharge is measured by partial discharge measurement device with high-frequency current transformer. Finally, the relationship between supply voltage and discharge intensity on each DC polarity and AC field stress can be successfully determined.
5. Temperature Dependence of PMD of the Optical Cables
Ahn, S.J. [Korea Electric Power Research Institute, Taejon (Korea)
2000-03-01
This report is relevant to the project {sup K}EPCO All-Optical Network Project{sup w}hich is being carried out by Computer and Communication Group in Power System Laboratory. This report is planned to be used as a reference guide for the PMD strategy of the KEPCO optical networks. The PMD of the optical cable installed in the air as OPGW is greatly affected by the environmental temperature change, unlike that of the optical cable installed underground. The variance was turned out to be 70% larger compared with that of underground optical cable and the time scale of the PMD was less than 5 min, in the worst case. Hence, the compensation technology should be chosen taking into account the properties of the aerial optical cables. (author). 6 refs., 3 figs., 1 tab.
6. The Mathematical Modelling of Heat Transfer in Electrical Cables
Bugajev Andrej; Jankevičiūtė Gerda; Tumanova Natalija
2014-01-01
This paper describes a mathematical modelling approach for heat transfer calculations in underground high voltage and middle voltage electrical power cables. First of the all typical layout of the cable in the sand or soil is described. Then numerical algorithms are targeted to the two-dimensional mathematical models of transient heat transfer. Finite Volume Method is suggested for calculations. Different strategies of nonorthogonality error elimination are considered. Acute triangles meshes ...
7. Loss and Inductance Investigation in Superconducting Cable Conductors
Olsen, Søren Krüger; Tønnesen, Ole; Træholt, Chresten;
1999-01-01
the layers are therefore studied theoretically. The current distribution between the superconducting layers is monitored as a function of transport current, and the results are compared with the expected current distribution given by our electrical circuit model.The AC-losses are measured as a...... Hz) the AC-loss was measured on cable #2 to 0.6W/mxphase. This is, to our knowledge, the lowest AC-loss (at 2kA and 77K) of a high temperature superconducting cable conductor reported so far....
8. UtilityTelecom_CABLE2005
Vermont Center for Geographic Information — The VT Cable System dataset (CABLE2005) includes lines depicting the extent of Vermont's cable system as of 12/31/2005. Numerous cable companies provide service in...
9. UtilityTelecom_CABLE2007
Vermont Center for Geographic Information — The VT Cable System dataset (CABLE2007) includes lines depicting the extent of Vermont's cable system as of 12/31/2007. Numerous cable companies provide service in...
10. Cable-fault locator
Cason, R. L.; Mcstay, J. J.; Heymann, A. P., Sr.
1979-01-01
Inexpensive system automatically indicates location of short-circuited section of power cable. Monitor does not require that cable be disconnected from its power source or that test signals be applied. Instead, ground-current sensors are installed in manholes or at other selected locations along cable run. When fault occurs, sensors transmit information about fault location to control center. Repair crew can be sent to location and cable can be returned to service with minimum of downtime.
11. Fault Location on Mixed Overhead Line and Cable Network
Han, Junyu
2015-01-01
Society is increasingly concerned about the environmental impact of energy systems, and prefers to locate power lines underground. In future, certain socially/environmentally sensitive overhead transmission feeders will need to include underground cable sections. Fault location, especially when using travelling waves, become complicated when the combined transmission line includes a number of discontinuities, such as junction points, teed points and fault points. Consequently, a diverse range...
12. Cable Supported Bridges
Gimsing, Niels Jørgen
Cable supported bridges in the form of suspension bridges and cable-stayed bridges are distinguished by their ability to overcome large spans.The book concentrates on the synthesis of cable supported bridges, covering both design and construction aspects. The analytical part covers simple methods...
13. Cable Television: Franchising Considerations.
Baer, Walter S.; And Others
This volume is a comprehensive reference guide to cable television technology and issues of planning, franchising, and regulating a cable system. It is intended for local government officials and citizens concerned with the development of cable television systems in their communities, as well as for college and university classes in…
14. Modeling vibration response and damping of cables and cabled structures
Spak, Kaitlin S.; Agnes, Gregory S.; Inman, Daniel J.
2015-02-01
In an effort to model the vibration response of cabled structures, the distributed transfer function method is developed to model cables and a simple cabled structure. The model includes shear effects, tension, and hysteretic damping for modeling of helical stranded cables, and includes a method for modeling cable attachment points using both linear and rotational damping and stiffness. The damped cable model shows agreement with experimental data for four types of stranded cables, and the damped cabled beam model shows agreement with experimental data for the cables attached to a beam structure, as well as improvement over the distributed mass method for cabled structure modeling.
15. Control of a long reach manipulator with suspension cables for waste storage tank remediation. Final report
A long reach manipulator will be used for waste remediation in large underground storage tanks. The manipulator's slenderness makes it flexible and difficult to control. A low-cost and effective method to enhance the manipulator's stiffness is proposed in this research by using suspension cables. These cables can also be used to accurately measure the position of the manipulator's wrist
16. Resistive cryogenic cable, phase III. Final report, April 18, 1974--March 31, 1977
None
1977-01-01
Work performed during 3 years of research on development of a foam-insulated underground cryogenic power transmission cable is reported. Information is included on the cryogenic envelope investigation; evaluation and aging study of electrical insulation; test system specifications; and cable system design and cost studies. (LCL)
17. Commercialization of Medium Voltage HTS Triax TM Cable Systems
Knoll, David
2012-12-31
The original project scope that was established in 2007 aimed to install a 1,700 meter (1.1 mile) medium voltage HTS Triax{TM} cable system into the utility grid in New Orleans, LA. In 2010, however, the utility partner withdrew from the project, so the 1,700 meter cable installation was cancelled and the scope of work was reduced. The work then concentrated on the specific barriers to commercialization of HTS cable technology. The modified scope included long-length HTS cable design and testing, high voltage factory test development, optimized cooling system development, and HTS cable life-cycle analysis. In 2012, Southwire again analyzed the market for HTS cables and deemed the near term market acceptance to be low. The scope of work was further reduced to the completion of tasks already started and to testing of the existing HTS cable system in Columbus, OH. The work completed under the project included: • Long-length cable modeling and analysis • HTS wire evaluation and testing • Cable testing for AC losses • Optimized cooling system design • Life cycle testing of the HTS cable in Columbus, OH • Project management. The 200 meter long HTS Triax{TM} cable in Columbus, OH was incorporated into the project under the initial scope changes as a test bed for life cycle testing as well as the site for an optimized HTS cable cooling system. The Columbus cable utilizes the HTS TriaxTM design, so it provided an economical tool for these of the project tasks.
18. SC Power leads and cables - Nominal Current Test Performance of 2 kA-Class High-Tc Superconducting Cable Conductors and Its Implications for Cooling Systems for Utility Cables
Willen, D. W. A; Daumling, M.; Rasmussen, C. N.; Træholt, Chresten; Olsen, Søren Krüger; Rasmussen, Carsten; Jensen, Kim Høj; Østergaard, Jacob; Kyhle, Anders; Tønnesen, Ole
The current carrying performance of 3-10 m long superconducting cable conductor models has been evaluated. A reduced energy loss compared to conventional cables can be obtained using high-Tc superconducting materials due to the limited resistive and ac hysteresis losses in some conductor configur...
19. Interstrand contact resistances of Bi-2212 Rutherford cables for SMES
Kawagoe, A. [Kagoshima University, Kohrimoto 1-21-40, Kagoshima-shi, Kagoshima 890-0065 (Japan)]. E-mail: [email protected]; Kawabata, Y. [Kagoshima University, Kohrimoto 1-21-40, Kagoshima-shi, Kagoshima 890-0065 (Japan); Sumiyoshi, F. [Kagoshima University, Kohrimoto 1-21-40, Kagoshima-shi, Kagoshima 890-0065 (Japan); Nagaya, S. [Chubu Electric Power Co. Inc., Kitazekiyama 20-1, Ohtakacho-aza, Midori-ku, Nagoya 249-8522 (Japan); Hirano, N. [Chubu Electric Power Co. Inc., Kitazekiyama 20-1, Ohtakacho-aza, Midori-ku, Nagoya 249-8522 (Japan)
2006-10-01
Interstrand contact resistances of Bi-2212 Rutherford cables for SMES coils were evaluated from a comparison between measured data and 2D-FEM analyses on interstrand coupling losses in these cables. The cables were composed of 30 non-twisted Bi-2212 strands with a diameter of 0.81 mm and a cable twist pitch of 90 mm. Three samples were measured; one of them had NiCr cores and the others had no cores. One of the latter two samples repeatedly experienced bending. The interstrand coupling losses were measured in liquid helium for the straight samples under transverse ac ripple magnetic fields superposed on dc bias magnetic fields. The transverse magnetic field was applied to the samples in directions both perpendicular and parallel to the flat face of the cable. The effect of the bending on the interstrand coupling losses could be neglected for the non-cored samples. The interstrand coupling losses of NiCr cored sample decreased by about 30% compared with the non-cored samples, in case the direction of the transverse magnetic fields applied to the cable is perpendicular to the flat face of the cable. Using these results and 2D-FEM analyses, taking into account that interstrand contact conditions vary from the center to the edge in the cross-section of cables, gave us the conclusion that the between side-by-side strands contact with metallurgical bond only in both edges of the cables.
20. Underground Mathematics
Hadlock, Charles R
2013-01-01
The movement of groundwater in underground aquifers is an ideal physical example of many important themes in mathematical modeling, ranging from general principles (like Occam's Razor) to specific techniques (such as geometry, linear equations, and the calculus). This article gives a self-contained introduction to groundwater modeling with…
1. 地下管线对通信电缆的屏蔽效应计算方法%Calculation method of electromagnetic shielding effects of underground pipelines to communication cables
周宇坤; 马信山
2001-01-01
An electromagnetic shielding calculation model of undergroundconductors is presented, which takes the inductive coupling and the resistive coupling into account simultaneously. The traditional electromagnetic shielding calculation method is improved by changing interpolating function with pipeline node currents in place of pipeline element currents. Based on the model, the electromagnetic shielding effectiveness of the buried pipeline to communication cables is calculated and the regularity of electromagnetic shielding effectiveness is discussed. The calculation results show that the dimension of pipeline and grounding resistances will affect shielding effectiveness.%提出了一种同时考虑感性耦合和阻性耦合时的地下管线对通信电缆的电磁屏蔽模型，以管线节点电流代替管线单元电流进行插值，改进了传统电磁屏蔽效应计算方法。在此基础上，进行了地下管线对地下通信电缆的电磁屏蔽系数计算，探讨了屏蔽保护的规律。计算结果表明，管线粗细和端接阻抗将明显影响屏蔽保护效果。
2. Inductance and current distribution analysis of a prototype HTS cable
This project is partly supported by NSFC Grant 51207146, RAEng Research Exchange scheme of UK and EPSRC EP/K01496X/1. Superconducting cable is an emerging technology for electricity power transmission. Since the high power capacity HTS transmission cables are manufactured using a multi-layer conductor structure, the current distribution among the multilayer structure would be nonuniform without proper optimization and hence lead to large transmission losses. Therefore a novel optimization method has been developed to achieve evenly distributed current among different layers considering the HTS cable structure parameters: radius, pitch angle and winding direction which determine the self and mutual inductance. A prototype HTS cable has been built using BSCCO tape and tested to validate the design the optimal design method. A superconductor characterization system has been developed using the Labview and NI data acquisition system. It can be used to measure the AC loss and current distribution of short HTS cables.
3. Dynamic Response Analysis of Towed Cable During Deployment/Retrieval
WANG Fei; HUANG Guo-liang; DENG De-heng
2008-01-01
A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR). The cable motion is described by the lumped parameter method, its corresponding boundary conditions are presented. In view of its varying length during DR, two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate, which is then used to determine the node number by a logic relation. For the discrete mathematical model of towed cable, an algorithm was developed to deal with the discrete governing equations. The simulation results indicate that the cable experiences more com- plex motions due to its varying length, and tension fluctuates seriously in the startup and ending stage of deployment/retrieval. The effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.
4. Electrical Aging Phenomena of Power Cables Aged by Switching Impulses
L.Cao; A.Zanwar; S.Grzybowski
2013-01-01
Due to the insufficient information regarding the aging phenomenon of cables caused by switching impulses,we aged 15 kV XLPE and EPR cable samples by 10000 switching impulses in experiments and tested them.Plus in order to compare the aging phenomenon under multi-stress conditions,additional EPR cable samples were aged by rated AC voltage and current with switching impulses superimposed.We used measurements of partial discharge parameters to monitor the cables' conditions during their aging process,and the AC breakdown voltages measurement to evaluate the cables after aging.Moreover,the Fourier transform infrared (FTIR) spectroscopy measurements revealed the changes of insulation materials after aging.The measurement results confirm that the accelerated aging of cable samples had taken place.The impacts of each individual aging factor are shown through the selected measurements and comparison.The study also helps to assess the reliability of the XLPE and EPR cables under similar condition while serving in power systems.
5. Southwire's High Temperature Superconducting Cable Development - Summary Report
ORNL for the DC Ic, voltage withstand, ac loss, and other properties using both the Vacuum and Pressure Terminations. The design concept was proven with the 5-m cables and the same design was used for the 30-m cables. Three 30-m cables were constructed during the first two quarters of 1999. The cables were made on flexible formers but they were introduced into three separate rigid vacuum jacketed pipes (VJP). The cables passed the DC Ic tests that were carried out at the manufacturing site. A site was developed at Southwire with a switch yard, liquid nitrogen tank, a cryogenic cooling and delivery system, and a control room with PLC control for the system. The HTS cables were installed by the third quarter of 1999. The HTS cables were energized Jan. 6, 2000. The official opening was carried out on Feb. 18, 2000. As of April 30, 2005 the HTS site has been operating at 100% load for >29,000 hours. Since June 1, 2001 the system has logged over 21,000 hours at full load without an operator on duty at the site. The cryogenic system has been under operation for more than two years and has proven very reliable. Southwire has developed World's First Industrial HTS cable and is continuing to prove its reliability. This report contains several sections outlined below that are related to Southwire's HTS cable development: (1) High Temperature Superconducting (HTS) Tapes; (2) Hand Wound 1-m Cables; (3) Development of Facilities for Construction and testing of HTS cables; (4) 5-m HTS Cables; (5) 30-m HTS Cables, Installation at Southwire; (6) Continued Developments; and (7) Publications. Each of the above sections provide only a short report. The details are given in separate volumes (Vol. 1 to Vol. 7) with separate appendices for each section. These are available at the Cofer Center Technical Library
6. Rokibaar Underground = Rock bar Underground
2008-01-01
Rokibaari Underground (Küütri 7, Tartu) sisekujundus, mis pälvis Eesti Sisearhitektide Liidu 2007. a. eripreemia. Sisearhitekt: Margus Mänd (Tammat OÜ). Margus Männist, tema tähtsamad tööd. Plaan, 5 värv. vaadet, foto M. Männist
7. Cable fault locator research
Cole, C. A.; Honey, S. K.; Petro, J. P.; Phillips, A. C.
1982-07-01
Cable fault location and the construction of four field test units are discussed. Swept frequency sounding of mine cables with RF signals was the technique most thoroughly investigated. The swept frequency technique is supplemented with a form of moving target indication to provide a method for locating the position of a technician along a cable and relative to a suspected fault. Separate, more limited investigations involved high voltage time domain reflectometry and acoustical probing of mine cables. Particular areas of research included microprocessor-based control of the swept frequency system, a microprocessor based fast Fourier transform for spectral analysis, and RF synthesizers.
8. Electrical power cable engineering
Thue, William A
2011-01-01
Fully updated, Electrical Power Cable Engineering, Third Edition again concentrates on the remarkably complex design, application, and preparation methods required to terminate and splice cables. This latest addition to the CRC Press Power Engineering series covers cutting-edge methods for design, manufacture, installation, operation, and maintenance of reliable power cable systems. It is based largely on feedback from experienced university lecturers who have taught courses on these very concepts.The book emphasizes methods to optimize vital design and installation of power cables used in the
9. The US market for high-temperature superconducting wire in transmission cable applications
Forbes, D
1996-04-01
Telephone interviews were conducted with 23 utility engineers concerning the future prospects for high-temperature superconducting (HTS) transmission cables. All have direct responsibility for transmission in their utility, most of them in a management capacity. The engineers represented their utilities as members of the Electric Power Research Institute`s Underground Transmission Task Force (which has since been disbanded). In that capacity, they followed the superconducting transmission cable program and are aware of the cryogenic implications. Nineteen of the 23 engineers stated the market for underground transmission would grow during the next decade. Twelve of those specified an annual growth rate; the average of these responses was 5.6%. Adjusting that figure downward to incorporate the remaining responses, this study assumes an average growth rate of 3.4%. Factors driving the growth rate include the difficulty in securing rights-of-way for overhead lines, new construction techniques that reduce the costs of underground transmission, deregulation, and the possibility that public utility commissions will allow utilities to include overhead costs in their rate base. Utilities have few plans to replace existing cable as preventive maintenance, even though much of the existing cable has exceeded its 40-year lifetime. Ten of the respondents said the availability of a superconducting cable with the same life-cycle costs as a conventional cable and twice the ampacity would induce them to consider retrofits. The respondents said a cable with those characteristics would capture 73% of their cable retrofits.
10. UtilityTelecom_CABLE2013
Vermont Center for Geographic Information — The VT Cable dataset (CABLE2013) includes lines depicting the extent of Vermont's cable modem broadband system as of 6/30/2013 in addition to those companies who do...
11. Cable tracking system proposal
The Experimental Facilities Division requires a labeling system to identify and catalog the instrumentation, control, and computer cables that will run throughout the building. Tom Sheridan from the MIS Group has already made some general suggestions about the information that could be included in an Oracle-based Cable Tracking System (E-mail text distributed by Gary Gunderson on the 27th of August). Glenn Decker's LS Note No. 191 is also relevant to the subject since it addresses name assignment rules for the storage ring devices. The intent of this note is to recommend a mechanism for tracking wires/cables, with enough specifics, to which all groups in the Division would adhere when pulling cables. Because most cables will run between various beamline devices, hutch safety components, and equipment racks, any method of tracking cables is related to the Equipment Tracking System. That system has been developed by the APS Project personnel and is described in the APS Project Equipment Tracking System Guidelines (DRAFT). It can be adopted to XFD's needs. Two essential features of the Cable Tracking System are: 1) Each cable shell have a unique Identifier, and 2) Cable label must contain information that is helpful during troubleshooting in the field. The Identifier is an alphanumeric string of characters that will originate in the Oraclebased Cable Tracking System. It is not necessary for the identifier to carry a lot of intelligence its primary purpose is simply to provide a link to the database. Bar-coding the Identifier would make it easy to combine cable information with the Equipment Tracking System
12. COPPER CABLE RECYCLING TECHNOLOGY
The United States Department of Energy (DOE) continually seeks safer and more cost-effective technologies for use in deactivation and decommissioning (D and D) of nuclear facilities. The Deactivation and Decommissioning Focus Area (DDFA) of the DOE's Office of Science and Technology (OST) sponsors large-scale demonstration and deployment projects (LSDDPs). At these LSDDPs, developers and vendors of improved or innovative technologies showcase products that are potentially beneficial to the DOE's projects and to others in the D and D community. Benefits sought include decreased health and safety risks to personnel and the environment, increased productivity, and decreased costs of operation. The Idaho National Engineering and Environmental Laboratory (INEEL) generated a list of statements defining specific needs and problems where improved technology could be incorporated into ongoing D and D tasks. One such need is to reduce the volume of waste copper wire and cable generated by D and D. Deactivation and decommissioning activities of nuclear facilities generates hundreds of tons of contaminated copper cable, which are sent to radioactive waste disposal sites. The Copper Cable Recycling Technology separates the clean copper from contaminated insulation and dust materials in these cables. The recovered copper can then be reclaimed and, more importantly, landfill disposal volumes can be reduced. The existing baseline technology for disposing radioactively contaminated cables is to package the cables in wooden storage boxes and dispose of the cables in radioactive waste disposal sites. The Copper Cable Recycling Technology is applicable to facility decommissioning projects at many Department of Energy (DOE) nuclear facilities and commercial nuclear power plants undergoing decommissioning activities. The INEEL Copper Cable Recycling Technology Demonstration investigated the effectiveness and efficiency to recycle 13.5 tons of copper cable. To determine the effectiveness
13. Magnetization losses in superconducting YBCO conductor-on-round-core (CORC) cables
Majoros, M.; Sumption, M. D.; Collings, E. W.; van der Laan, D. C.
2014-12-01
Described are the results of magnetization loss measurements made at 77 K on several YBCO conductor-on-round-core (CORC) cables in ac magnetic fields of up to 80 mT in amplitude and frequencies of 50 to 200 Hz, applied perpendicular to the cable axis. The cables contained up to 40 tapes that were wound in as many as 13 layers. Measurements on the cables with different configurations were made as functions of applied ac field amplitude and frequency to determine the effects of their layout on ac loss. In large scale devices such as e.g. Superconducting Magnetic Energy Storage (SMES) magnets, the observed ac losses represent less than 0.1% of their stored energy.
14. Flux-transfer losses in helically wound superconducting power cables
Clem, John R; Malozemoff, A P
2013-06-25
Minimization of ac losses is essential for economic operation of high-temperature superconductor (HTS) ac power cables. A favorable configuration for the phase conductor of such cables has two counter-wound layers of HTS tape-shaped wires lying next to each other and helically wound around a flexible cylindrical former. However, if magnetic materials such as magnetic substrates of the tapes lie between the two layers, or if the winding pitch angles are not opposite and essentially equal in magnitude to each other, current distributes unequally between the two layers. Then, if at some point in the ac cycle the current of either of the two layers exceeds its critical current, a large ac loss arises from the transfer of flux between the two layers. A detailed review of the formalism, and its application to the case of paramagnetic substrates including the calculation of this flux-transfer loss, is presented.
15. Test results of a 30-m HTS cable pre-demonstration system in Yokohama project
High temperature superconducting cable demonstration project supported by Ministry of Economy, Trade and Industry and New Energy and Industrial Technology Development Organization has started since FY 2007 in Japan. Target of this project is to operate a 66 kV, 200 MVA HTS cable in a live grid in order to demonstrate its reliability and stable operation. A demonstration site has been decided to Asahi substation which is located in Yokohama. The cable length will be decided to between 200 and 300 m depending on a site configuration. Various preliminary tests such as critical current, ac losses, fault current loading, mechanical tests, have been conducted by using short core samples in order to confirm a HTS cable design and a cable-to-cable joint structure. From these test results, a HTS cable, a joint and a termination have been designed to meet the required specifications. To verify their performances before the installation of the HTS cable system in Yokohama, a 30-m HTS cable was manufactured and various sample tests were conducted as shipping test. The critical current of the HTS conductor and shield were 6.1 kA and 7.1 kA, respectively. The AC loss was 0.83 W/m/ph at 2 kArms, 60 Hz. As withstand voltage tests, AC 90 kV for 3 h and lightning impulse at ±385 kV were applied to cable core, successfully. These test results has confirmed that the 30-m cable had good properties as designed and satisfied the required specifications. After the success of the shipping tests, the 30-m HTS cable pre-demonstration system has been installed at SEI factory. The cable system will be operated and checked the various performances in this summer.
16. Test results of a 30-m HTS cable pre-demonstration system in Yokohama project
Yumura, H.; Ashibe, Y.; Ohya, M.; Itoh, H.; Watanabe, M.; Yatsuka, K.; Masuda, T.; Honjo, S.; Mimura, T.; Kitoh, Y.; Noguchi, Y.
2010-11-01
High temperature superconducting cable demonstration project supported by Ministry of Economy, Trade and Industry and New Energy and Industrial Technology Development Organization has started since FY 2007 in Japan. Target of this project is to operate a 66 kV, 200 MVA HTS cable in a live grid in order to demonstrate its reliability and stable operation. A demonstration site has been decided to Asahi substation which is located in Yokohama. The cable length will be decided to between 200 and 300 m depending on a site configuration. Various preliminary tests such as critical current, ac losses, fault current loading, mechanical tests, have been conducted by using short core samples in order to confirm a HTS cable design and a cable-to-cable joint structure. From these test results, a HTS cable, a joint and a termination have been designed to meet the required specifications. To verify their performances before the installation of the HTS cable system in Yokohama, a 30-m HTS cable was manufactured and various sample tests were conducted as shipping test. The critical current of the HTS conductor and shield were 6.1 kA and 7.1 kA, respectively. The AC loss was 0.83 W/m/ph at 2 kA rms, 60 Hz. As withstand voltage tests, AC 90 kV for 3 h and lightning impulse at ±385 kV were applied to cable core, successfully. These test results has confirmed that the 30-m cable had good properties as designed and satisfied the required specifications. After the success of the shipping tests, the 30-m HTS cable pre-demonstration system has been installed at SEI factory. The cable system will be operated and checked the various performances in this summer.
17. Modeling of a distributed constant electric circuit considering contact resistance and coupling loss analyses for cable twisted at multiple stages
AC losses in multi-strand superconducting cables, utilized in large-scale applications such as fusion machines, are governed by the contact resistance between strands. Especially, in cable twisted at multiple-stages, a variety of magnetic field diffusion time constants exist and these correspond to the quantity of inter-strand coupling loss in each cabling stage. The rate of magnetic field change is less than several T/s in an average fusion machine. Under this condition, the magnetic field penetrates the cable well and the coupling current circuit with the larger time constant causes larger AC loss. Here, the time constant is equal to the leakage inductance divided by the resistance along the coupling current loop. Therefore, by evaluating the coupling current in the larger loop, which consists of a higher twisting stage (e.g., usually the final cabling stage), the loss in the entire cable can be determined. The leakage inductance between sub-cables can be estimated by considering the electrical centers. On the other hand, inter-sub-cable contact resistance was not previously evaluated due to its complexity. In this study, we established an inter-sub-cable contact resistance model that allows the AC loss in cable with multiple twisting stages to be evaluated numerically. The modeling of contact resistance between sub-cables is discussed in detail. (author)
18. Grounding Effect on Common Mode Interference of Underground Inverter
Cheng, Qiang; Cheng, Ning; LI Zhen-shuang
2013-01-01
For the neutral point not grounded characteristics of underground power supply system in coal mine, this paper studied common mode equivalent circuit of underground PWM inverter, and extracted parasitic parameters of interference propagation path. The author established a common mode and differential mode model of underground inverter. Taking into account the rise time of PWM, the simulation results of conducted interference by Matlab software is compared with measurement spectrum on the AC s...
19. High current, low loss high temperature superconductor cables, concepts, properties and applications
High Temperature Superconductors of the second generation (HTS-2G) became an industrial product during the recent years and are applied in several concepts of high current cables for a variety of applications. Low Losses, a thermal stabilization and mechanical strength are the requested features of the cables. We present an overview on the different cable concepts, their performance and the prospected DC and AC applications. Roebel cables and the CORC cable design are in particular suitable for AC operated high current devices as big generators, motors and large magnets. The performance of such cables was investigated under different conditions, as in pancake coils and layered windings. The behavior of the cables could meanwhile quite well be understood and described by FEM modeling. We also report on advanced cable versions which are equipped with a filamentary structure by means of laser assisted grooving of the superconducting layer. For some applications as large fusion magnets and accelerator magnets, even higher currents are requested. For such purpose Rutherford cables and more sophisticated concepts and cable designs are under investigation. We present the first results on such concepts and discuss the further research to be done. A final general outlook will indicate the prospects for the different applications. (author)
20. Albany Hts Cable Project Long Term In-Grid Operation Status Update
Yumura, H.; Masuda, T.; Watanabe, M.; Takigawa, H.; Ashibe, Y.; Ito, H.; Hirose, M.; Sato, K.
2008-03-01
High-temperature superconducting (HTS) cable systems are expected to be a solution for improvement of the power grid and three demonstration projects in the real grid are under way in the United States. One of them is the Albany, NY Cable Project, involving the installation and operation of a 350 meter HTS cable system with a capacity of 34.5kV, 800A, connecting between two substations in National Grid's electric utility system. A 320 meter and a 30 meter cable are installed in underground conduit and connected together in a vault. The cables were fabricated with 70km of DI-BSCCO wire in a 3 core-in-one cryostat structure. The cable installation of a 320 meter and a 30 meter section was completed successfully using the same pulling method as a conventional underground cable. After the cable installation, the joint and two terminations were assembled at the Albany site. After the initial cooling of the system, the commissioning tests such as the critical current, heat loss measurement and DC withstand voltage test were conducted successfully. The in-grid operation began on July 20th, 2006 and operated successfully in unattended condition through May 1st, 2007. In the 2nd phase of the Albany project, the 30 meter section is to be replaced by a YBCO cable. The YBCO cable had been developed and a new 30 meter cable was manufactured by using SuperPower's YBCO coated conductors. This paper describes the latest status of the Albany cable project.
1. Infiniband Based Cable Comparison
Minich, Makia [ORNL
2007-07-01
As Infiniband continues to be more broadly adopted in High Performance Computing (HPC) and datacenter applications, one major challenge still plagues implementation: cabling. With the transition to DDR (double data rate) from SDR (single datarate), currently available Infiniband implementations such as standard CX4/IB4x style copper cables severely constrain system design (10m maximum length for DDR copper cables, thermal management due to poor airflow, etc.). This paper will examine some of the options available and compare performance with the newly released Intel Connects Cables. In addition, we will take a glance at Intel's dual-core and quad-core systems to see if core counts have noticeable effect on expected IO patterns.
2. Underground logistics
Foraz, K; CERN. Geneva. TS Department
2005-01-01
More than 80’000 tons of materials have to be transported and installed down into the LHC tunnel. The magnet assemblies which represent about 50’000 tons, will be transported according to the master schedule between March 2005 and November 2006. Considering that these about 1’800 cryo-magnets will be transported at a maximum speed of 3 km/h in a narrow tube (where installation works and hardware commissioning activities are ongoing) this duration of 21 months is a real challenge. This paper aims at describing: - the information flows between the different people involved in the logistics attached to the cryo-magnets, - the organization chosen within the Installation Coordination group, - the problems encountered so far and the solutions adopted. The coordination process with other underground transport and activities, mainly for the QRL will also be presented.
3. Magnet cable manufacturing
The superconducting magnets used in the construction of particle accelerators are mostly built from flat, multistrand cables with rectangular or keystoned cross sections. The superconducting strands are mostly circular but a design of a cable made of preflattened wires was proposed a few years ago under the name of Berkeley flat; such cable shows some interesting characteristics. Another design consists of a few smaller precabled wires (e.g. 6 around 1). This configuration allows smaller filaments and a better transposition of the current elements. The Superconducting Super Collider project involves the largest amount of superconducting cable ever envisaged for a single machine. Furthermore, the design calls for exceptional accuracy and improved characteristics of the cable. A part of the SSC research and development program is focused on these important questions. In this paper we emphasize the difference between the conventional cabling and wires with superconducting. A new concept for the tooling will be introduced as well as the necessary characteristics of a specialized cabler. 5 figs
4. A Cool-down and Fault Study of a Long Length HTS Power Transmission Cable
Yuan, J.; Maguire, J.; Allais, A.; Schmidt, F.
2006-04-01
High temperature superconductor (HTS) power transmission cables offer significant advantages in power density over conventional copper-based cables. Currently the US Department of Energy is funding the design, development, and demonstration of the first long length, transmission level voltage, cold dielectric, underground high temperature superconductor power cable. The cable is 620 meters long and is designed for permanent installation in the Long Island Power Authority (LIPA) grid. The cable is specified to carry 574 MVA at a voltage of 138 kV and is designed to withstand a 69 kA fault current for a duration of 200ms. The superconducting state of the cable conductors is maintained by circulating sub-cooled liquid nitrogen, which flows through one phase conductor of the cable and returns through the other two. As HTS cables develop and lengths increase to what may be considered commercial, it is critical to study the cable thermal behavior during cool-down process and fault condition to avoid any possible damage to the cable core due to the thermal stress, over heating or bubble formation. This paper reviews the efforts that have been made to study the cool-down process and fault condition. Descriptions of the transient thermal and fluid model are provided. A discussion of the simulation results is also included.
5. Report on full-scale horizontal cable tray fire tests, FY 1988
In recent years, there has been much discussion throughout industry and various governmental and fire protection agencies relative to the flammability and fire propagation characteristics of electrical cables in open cable trays. It has been acknowledged that under actual fire conditions, in the presence of other combustibles, electrical cable insulation can contribute to combustible fire loading and toxicity of smoke generation. Considerable research has been conducted on vertical cable tray fire propagation, mostly under small scale laboratory conditions. In July 1987, the Fermi National Accelerator Laboratory initiated a program of full scale, horizontal cable tray fire tests, in the absence of other building combustible loading, to determine the flammability and rate of horizontal fire propagation in cable tray configurations and cable mixes typical of those existing in underground tunnel enclosures and support buildings at the Laboratory. The series of tests addressed the effects of ventilation rates and cable tray fill, fire fighting techniques, and effectiveness and value of automatic sprinklers, smoke detection and cable coating fire barriers in detecting, controlling or extinguishing a cable tray fire. This report includes a description of the series of fire tests completed in June 1988, as well as conclusions reached from the test results
6. Free and forced convective cooling of pipe-type electric cables. Volume 1: forced cooling of cables. Final report
Chato, J.C.; Crowley, J.M.
1981-05-01
A multi-faceted research program has been performed to investigate in detail several aspects of free and forced convective cooling of underground electric cable systems. There were two main areas of investigation. The first one reported in this volume dealt with the fluid dynamic and thermal aspects of various components of the cable system. In particular, friction factors for laminar flow in the cable pipes with various configurations were determined using a finite element technique; the temperature distributions and heat transfer in splices were examined using a combined analytical numerical technique; the pressure drop and heat transfer characteristics of cable pipes in the transitional and turbulent flow regime were determined experimentally in a model study; and full-scale model experimental work was carried out to determine the fluid dynamic and thermal characteristics of entrance and exit chambers for the cooling oil. The second major area of activity, reported in volume 2, involved a feasibility study of an electrohydrodynamic pump concept utilizing a traveling electric field generated by a pumping cable. Experimental studies in two different configurations as well as theoretical calculations showed that an electrohydrodynamic pump for the moving of dielectric oil in a cable system is feasible.
7. Water underground
de Graaf, Inge
2015-04-01
The world's largest assessable source of freshwater is hidden underground, but we do not know what is happening to it yet. In many places of the world groundwater is abstracted at unsustainable rates: more water is used than being recharged, leading to decreasing river discharges and declining groundwater levels. It is predicted that for many regions of the world unsustainable water use will increase, due to increasing human water use under changing climate. It would not be long before shortage causes widespread droughts and the first water war begins. Improving our knowledge about our hidden water is the first step to stop this. The world largest aquifers are mapped, but these maps do not mention how much water they contain or how fast water levels decline. If we can add a third dimension to the aquifer maps, so a thickness, and add geohydrological information we can estimate how much water is stored. Also data on groundwater age and how fast it is refilled is needed to predict the impact of human water use and climate change on the groundwater resource.
8. Space Charge Accumulation under Effects of Temperature Gradient and Applied Voltage Reversal on Solid Dielectric DC Cable
Choo, Wilson; Chen, George; Swingler, Steve
2009-01-01
A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial ac XLPE power cables under an application of 80 kV dc supply at different temperature gradients and during external voltage reversal are discussed in thi...
9. Analysis of AC loss in superconducting power devices calculated from short sample data
Rabbers, J.J.; Haken, ten, Bennie; Kate, ten, F.J.W.
2003-01-01
A method to calculate the AC loss of superconducting power devices from the measured AC loss of a short sample is developed. In coils and cables the magnetic field varies spatially. The position dependent field vector is calculated assuming a homogeneous current distribution. From this field profile and the transport current, the local AC loss is calculated. Integration over the conductor length yields the AC loss of the device. The total AC loss of the device is split up in different compone...
10. EHV/HV Underground Cable Systems for Power Transmission
Bak, Claus Leth
Power transmission is facing its largest challenges ever with regards to handling a transition from today’s fossil‐based power production into renewable sources of generation. We can no longer place power plants close to centres of consumption; they must be located where the natural resources are...... to be found. One very good example of this is offshore wind power plants. The current transmission system is laid out in a traditional manner, which is based on the idea of not transporting power over longer distances as the power plants have been located near centres of consumption. It has merely...... layout of the transmission system must be re‐thought in order to accommodate the transmission needs for the future. New lines have to be constructed. Transmission lines are usually laid out as overhead lines, which are large structures, i.e. a 400 kV power pylon is 50 meters high. According to public...
11. Pyrotechnic-actuated cable release
Hanson, R. W.
1968-01-01
Remote, unattended means has been designed and reduced to practice that retains and then releases an attached load by means of a restrained cable. The cable is released by an electrical impulse on signal.
12. The Electrical Aspects of the choice of Former in a High T-c Superconducting Power Cable
Däumling, Manfred; Kühle (fratrådt), Anders Van Der Aa; Olsen, Søren Krüger; Træholt, Chresten; Tønnesen, Ole
1999-01-01
design of a cable. The diameter of the former determines the overall diameter of the total cable, influences the heat loss to the ambient and enters into the total AC-losses. Depending on whether the former is made of a good or poor electrical conductor eddy currents in the former itself may also...
13. Improved GPS travelling wave fault locator for power cables by using wavelet analysis
Zhao, W.; Song, Y.H.; Chen, W.R. [Brunel Univ., Dept. of Electronics and Computer Engineering, Uxbridge (United Kingdom)
2001-06-01
The paper propose an improved approach to cable-fault location, which is essentially based on synchronised sampling technique, wavelet analysis and travelling wave principle. After an outline of the new scheme and brief introduction to the three major techniques, wavelet analysis of faulty transient waveforms is conducted in details to determine the best wavelet levels for this particular application. Then a 400 kV underground cable system simulated by the Alternative Transient Program (ATP) under various system and fault conditions is used to fully evaluate the approach. Numerical results show that this scheme is reliable and accurate with errors of less than 2% of the length of the cable line. (Author)
14. Study on interstrand coupling losses in Rutherford-type superconducting cables
Two sets of experimental apparatus for measuring the AC losses in superconducting strands and Rutherford-type cable conductors have been constructed. A few strand samples and a number of compacted cable samples with and without a CuMn matrix have been measured. The hysteresis loss, loss from coupling within strands and loss from coupling between strands in cables have been distinguished from each other. The results show that, even for Rutherford cables without any soldering and coating, their AC losses may be quite different from each other due to the variation of the interstrand coupling loss. For cables without a CuMn matrix, interstrand coupling loss increases nearly according to a geometrical series with an increase of curing temperature simulating coil fabrication. However, cables with the CuMn matrix show a relatively small curing temperature dependence. For most of the samples, losses do not show any evident dependence on the mechanical pressure. Interstrand resistances in one of these cables have also been measured; the results indicate that the tendency for a decrease in the interstrand resistances is consistent with the results of AC loss measurements. (author)
15. Field Demonstration of a 24-kV Superconducting Cable at Detroit Edison
Kelley, Nathan; Corsaro, Pietro
2004-12-01
Customer acceptance of high temperature superconducting (HTS) cable technology requires a substantial field demonstration illustrating both the system's technical capabilities and its suitability for installation and operation within the utility environment. In this project, the world's first underground installation of an HTS cable using existing ductwork, a 120 meter demonstration cable circuit was designed and installed between the 24 kV bus distribution bus and a 120 kV-24 kV transformer at Detroit Edison's Frisbie substation. The system incorporated cables, accessories, a refrigeration system, and control instrumentation. Although the system was never put in operation because of problems with leaks in the cryostat, the project significantly advanced the state-of-the-art in the design and implementation of Warm Dielectric cable systems in substation applications. Lessons learned in this project are already being incorporated in several ongoing demonstration projects.
16. Design and performance of ultra-high-density optical fiber cable with rollable optical fiber ribbons
Hogari, Kazuo; Yamada, Yusuke; Toge, Kunihiro
2010-08-01
This paper proposes a novel ultra-high-density optical fiber cable that employs rollable optical fiber ribbons. The cable has great advantages in terms of cable weight and diameter, and fiber splicing workability. Moreover, it will be easy to install in a small space in underground ducts and on residential and business premises. The structural design of the rollable optical fiber ribbon is evaluated theoretically and experimentally, and an optimum adhesion pitch P in the longitudinal direction is obtained. In addition, we examined the performance of ultra-high-density cables with a small diameter that employ rollable optical fiber ribbons and bending-loss insensitive optical fibers. The transmission, mechanical and mid-span access performance of these cables was confirmed to be excellent.
17. Field Demonstration of a 24-kV Superconducting Cable at Detroit Edison
Customer acceptance of high temperature superconducting (HTS) cable technology requires a substantial field demonstration illustrating both the system's technical capabilities and its suitability for installation and operation within the utility environment. In this project, the world's first underground installation of an HTS cable using existing ductwork, a 120 meter demonstration cable circuit was designed and installed between the 24 kV bus distribution bus and a 120 kV-24 kV transformer at Detroit Edison's Frisbie substation. The system incorporated cables, accessories, a refrigeration system, and control instrumentation. Although the system was never put in operation because of problems with leaks in the cryostat, the project significantly advanced the state-of-the-art in the design and implementation of Warm Dielectric cable systems in substation applications. Lessons learned in this project are already being incorporated in several ongoing demonstration projects
18. The Danish Superconducting Cable Project
Tønnesen, Ole
1997-01-01
The design and construction of a superconducting cable is described. The cable has a room temperature dielectric design with the cryostat placed inside the electrical insulation.BSCCO 2223 superconducting tapes wound in helix form around a former are used as the cable conductor. Results from...
19. Cable Television Information.
New York State Education Dept. , Albany. Bureau of Mass Communications.
Cable television for the State of New York is discussed in detail with relation to: (1) the regents of the University of the State of New York, (2) legislation, (3) planning and proposals for franchises, (4) the Federal Communications Commission, (5) access rules, (6) a list of companies and those serving schools, and (7) federal/state/local…
20. Long term investigation of thermal behaviour of 110 kV underground transmission lines in the Belgrade area
Sredojevic, M.R.; Naumov, R.M.; Popovic, D.P. [Nikola Tesla Electrical Engineering Inst., Belgrade (Yugoslavia); Simic, M.D. [Electrical Utility Co., Belgrade (Yugoslavia)
1997-12-31
The paper describes the procedure for applying a special cable backfill material, developed and manufactured at the Institute ``Nikola Tesla`` for the thermal stabilisation and reduction of hot spot cable operating temperature, on specific hot spots of 110 kV underground transmission lines in the Belgrade area. The results presented in this paper are an important contribution to the proof of the justification and necessity of defining and introducing in practice new procedures for the thermal stabilisation and reduction of operating temperature of existing, as well as of new, underground transmission cable lines to be built. (author)
1. Internal coaxial cable seal system
Hall, David R.; Sneddon, Cameron; Dahlgren, Scott Steven; Briscoe, Michael A.
2006-07-25
The invention is a seal system for a coaxial cable and is placed within the coaxial cable and its constituent components. A series of seal stacks including load ring components and elastomeric rings are placed on load bearing members within the coaxial cable sealing the annular space between the coaxial cable and an electrical contact passing there through. The coaxial cable is disposed within drilling components to transmit electrical signals between drilling components within a drill string. The seal system can be used in a variety of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.
2. Long length HTS cable with integrated FCL property
The past years have shown the growth of bottlenecks in electric power grids, among other reasons caused by the increasing demand of energy in the form of electricity and by the large-scaled integration of renewable sources. As solving of these challenges by means of traditional solutions appears to be more and more problematic, the need for new technology solutions has become apparent. The HTS cable technology demonstrates a great potential in solving of grid congestion issues. In addition to their large power transport capacity and low losses, modern-generation HTS cables also have an integrated fault-current limiting (FCL) property. Applications of such cables in power grids will help to solve fault-current issues when connecting new generators, and dispersed and large-scale renewable sources. As HTS cables, used in current projects, are limited to hundreds of meters in length, they have still not been used for energy transport over long distances. The Dutch DSO Alliander, together with Ultera, is working on the development of a 6 km FCL HTS cable for installation in the Alliander's HV grid. In order to get the low-loss benefits of the HTS technology, a cooling system with a high efficiency is needed. The FCL HTS cable will be cooled by one cooling station at each end of the cable, using a liquid nitrogen coolant. Alliander and Ultera have established and work to achieve technical performance targets believed to be required to realise a 6 km long, 50 kV retrofit system with a power rating of 250 MVA with cooling stations only at the two ends of the cable system. These targets aim to reduce the superconductor's AC loss at a nominal current, reduce the heat leak of the thermally insulating envelope, increase the voltage rating and reduce the friction coefficient of the coolant flow.
3. Method for analysis the complex grounding cables system
A new iterative method for the analysis of the performances of the complex grounding systems (GS) in underground cable power networks with coated and/or uncoated metal sheathed cables is proposed in this paper. The analyzed grounding system consists of the grounding grid of a high voltage (HV) supplying transformer station (TS), middle voltage/low voltage (MV/LV) consumer TSs and arbitrary number of power cables, connecting them. The derived method takes into consideration the drops of voltage in the cable sheets and the mutual influence among all earthing electrodes, due to the resistive coupling through the soil. By means of the presented method it is possible to calculate the main grounding system performances, such as earth electrode potentials under short circuit fault to ground conditions, earth fault current distribution in the whole complex grounding system, step and touch voltages in the nearness of the earthing electrodes dissipating the fault current in the earth, impedances (resistances) to ground of all possible fault locations, apparent shield impedances to ground of all power cables, e.t.c. The proposed method is based on the admittance summation method [1] and is appropriately extended, so that it takes into account resistive coupling between the elements that the GS. (Author)
4. Design and evaluation of 66 kV-class HTS power cable using REBCO wires
Ohya, M., E-mail: [email protected] [Sumitomo Electric Industries, Ltd., 1-1-3, Shimaya, Konohana-ku, Osaka 554-0024 (Japan); Yumura, H.; Masuda, T. [Sumitomo Electric Industries, Ltd., 1-1-3, Shimaya, Konohana-ku, Osaka 554-0024 (Japan); Amemiya, N. [Kyoto University, Kyoto Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8530 (Japan); Ishiyama, A. [Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Ohkuma, T. [International Superconductivity Technology Center, 1-10-13, Shinonome, Koto-ku, Tokyo 135-0062 (Japan)
2011-11-15
A 4-layer cable conductor was manufactured using 4-mm wide REBCO wires with low magnetic textured substrates. The AC loss of the cable conductor was 1.5 W/m at 5 kA. Our cables are expected to achieve the AC loss target of less than 2 W/m/ph at 5 kA. Over-current tests (max. 31.5 kA, 2 s) were conducted for a cable sample and its soundness was verified. A 5 kA-class current lead was also developed. Sumitomo Electric (SEI) has been involved in the development of 66 kV-class HTS cables using REBCO wires. One of the technical targets in this project is to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI has developed a clad-type of textured metal substrate with lower magnetization loss compared with a conventional NiW substrate. In addition, 30 mm-wide REBCO tapes were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The AC loss of a manufactured 4-layer cable conductor was 1.5 W/m at 5 kA at 64 K. Given that the AC loss in a shield layer is supposed to be one-fourth of a whole cable core loss, our cables are expected to achieve the AC loss target of less than 2 W/m/phase at 5 kA. Another important target is to manage a fault current. A cable core was designed and fabricated based on the simulation findings, and over-current tests (max. 31.5 kA, 2 s) were conducted to check its performance. The critical current value of the cable cores were measured before and after the over-current tests and verified its soundness. A 5 kA-class current lead for the cable terminations was also developed. The current loading tests were conducted for the developed current leads. The temperature distribution of the current leads reached to the steady-state within less than 12 h, and it was confirmed that the developed current lead has enough capacity of 5 kA loading.
5. Design and evaluation of 66 kV-class HTS power cable using REBCO wires
A 4-layer cable conductor was manufactured using 4-mm wide REBCO wires with low magnetic textured substrates. The AC loss of the cable conductor was 1.5 W/m at 5 kA. Our cables are expected to achieve the AC loss target of less than 2 W/m/ph at 5 kA. Over-current tests (max. 31.5 kA, 2 s) were conducted for a cable sample and its soundness was verified. A 5 kA-class current lead was also developed. Sumitomo Electric (SEI) has been involved in the development of 66 kV-class HTS cables using REBCO wires. One of the technical targets in this project is to reduce the AC loss to less than 2 W/m/phase at 5 kA. SEI has developed a clad-type of textured metal substrate with lower magnetization loss compared with a conventional NiW substrate. In addition, 30 mm-wide REBCO tapes were slit into 4 mm-wide strips, and these strips were wound spirally on a former with small gaps. The AC loss of a manufactured 4-layer cable conductor was 1.5 W/m at 5 kA at 64 K. Given that the AC loss in a shield layer is supposed to be one-fourth of a whole cable core loss, our cables are expected to achieve the AC loss target of less than 2 W/m/phase at 5 kA. Another important target is to manage a fault current. A cable core was designed and fabricated based on the simulation findings, and over-current tests (max. 31.5 kA, 2 s) were conducted to check its performance. The critical current value of the cable cores were measured before and after the over-current tests and verified its soundness. A 5 kA-class current lead for the cable terminations was also developed. The current loading tests were conducted for the developed current leads. The temperature distribution of the current leads reached to the steady-state within less than 12 h, and it was confirmed that the developed current lead has enough capacity of 5 kA loading.
6. Full-scale horizontal cable-tray tests: Fire-propagation characteristics
At the Fermi National Accelerator Center (Fermilab), as at any high-energy physics laboratory, the experimental program depends on complex arrays of equipment that require years to assemble and place in service. These equipment arrays are typically located in enclosed tunnels or experimental halls and could be destroyed by rapidly propagating, uncontrolled fire. Cable trays, both vertical and horizontal, are an integral and ubiquitous component of these installations. Concurrently, throughout industry and within the professional fire-fighting community, there has been concern over the flammability and fire propagation characteristics of electrical cables in open cable trays. While some information was available concerning fire propagation in vertical cable trays, little was known about fires in horizontal cable trays. In view of the potential for loss of equipment and facilities, not to mention the programmatic impact of a fire, Fermilab initiated a program of full-scale, horizontal cable-tray fire tests to determine the flammability and rate of horizontal fire propagation in cable-tray configurations and cable mixed typical of those existing in underground tunnel enclosures and support buildings as Fermilab. This series of tests addressed the effects of ventilation rates and cable-tray fill, fire-fighting techniques, and the effectiveness and value of automatic sprinklers, smoke detection, and cable-coating fire barriers in detecting, controlling, or extinguishing a cable-tray fire. Detailed descriptions of each fire test, including sketches of cable-tray configuration and contents, instrumentation, ventilation rates, Fermilab Fire Department personnel observations, photographs, and graphs of thermocouple readings are available in a report of these tests prepared by the Fermilab Safety Section
7. New Passive Methodology for Power Cable Monitoring and Fault Location
Kim, Youngdeug
The utilization of power cables is increasing with the development of renewable energy and the maintenance replacement of old overhead power lines. Therefore, effective monitoring and accurate fault location for power cables are very important for the sake of a stable power supply. The recent technologies for power cable diagnosis and temperature monitoring system are described including their intrinsic limitations for cable health assessment. Power cable fault location methods are reviewed with two main categories: off-line and on-line data based methods. As a diagnostic and fault location approach, a new passive methodology is introduced. This methodology is based on analyzing the resonant frequencies of the transfer function between the input and output of the power cable system. The equivalent pi model is applied to the resonant frequency calculation for the selected underground power cable transmission system. The characteristics of the resonant frequencies are studied by analytical derivations and PSCAD simulations. It is found that the variation of load magnitudes and change of positive power factors (i.e., inductive loads) do not affect resonant frequencies significantly, but there is considerable movement of resonant frequencies under change of negative power factors (i.e., capacitive loads). Power cable fault conditions introduce new resonant frequencies in accordance with fault positions. Similar behaviors of the resonant frequencies are shown in a transformer (TR) connected power cable system with frequency shifts caused by the TR impedance. The resonant frequencies can be extracted by frequency analysis of power signals and the inherent noise in these signals plays a key role to measure the resonant frequencies. Window functions provide an effective tool for improving resonant frequency discernment. The frequency analysis is implemented on noise laden PSCAD simulation signals and it reveals identical resonant frequency characteristics with theoretical
8. EIGENFREQUENCY ANALYSIS OF CABLE STRUCTURES WITH INCLINED CABLES
William Paulsen; Greg Slayton
2006-01-01
The approximate eigenfrequencies for the in-plane vibrations of a cable structure consisting of inclined cables, together with point masses at various points were computed. It was discovered that the classical transfer matrix method was inadequate for this task, and hence the larger exterior matrices were used to determine the eigenfrequency equation. Then predictions of the dynamics of the general cable structure based on the asymptotic estimates of the exterior matrices were made.
9. Applied use of combustion turbine generators as a station blackout alternate AC power source
In response to the 10 CFR 50.63 Station Blackout Rule and NRC Regulatory Guide (RG) 1.155, Arizona Public Service Company (APS) opted to install dual 13.8kV, 3400kW black start combustion turbine generators (CTG's) as an alternate AC (AAC) power source at the Palo Verde Nuclear Generating Station (PVNGS). These CTG's provide AC power to critical plant loads in the event of a Station Blackout (SBO) in any one of the three PVNGS units. The AAC power source entered service in the fall of 1993 for the first PVNGS unit. Connection of the AAC source for the other two nuclear units will be complete by mid-1995. Two redundant CTGs were used to provide assurance that the AAC system availability requirements of RG 1.155 of 95% were met. A CTG site was chosen near an existing source of diesel fuel oil that was reasonably distant from the plant switchyard. The CTG's were installed along with a prefabricated turbine control room (TCR) which houses the CTG control equipment and associated power distribution equipment and battery systems. Cables were routed from the CTG site to each of the PVNGS units utilizing both new and existing underground duct banks. The cables were sized for the combined output of both CTG's at maximum power output for site worst case conditions. At each of the PVNGS units, additional switchgear cubicles were added to provide an interface with the existing plant power distribution system at a point upstream of the safety related power system. A test program was developed by engineering that tested all aspects of the installation and proved its capability to fulfill its purpose. Testing ranged from verifying emergency lighting adequacy to emissions testing and a complete simulation of a SBO. CTG performance was evaluated and verified to meet all expectations
10. Stray current induced corrosion in lightning rod cables of 525 kV power lines towers: a case study
Wojcicki, F. R.
2003-12-01
Full Text Available With the growth of several areas in modem society, the necessity to generate and carry electrical energy to big cities has greatly increased. Cables supported by power towers with galvanized steel foundation usually carry energy. As the foundations are underground they may cause high rates of corrosion. These are usually detected by a conventional potential measurement using a Cu/CuSO4 reference electrode. It is believed that corrosion results from stray currents that flow through the ground to close the loop between neighboring towers. Stray currents originate in the lightning rod cables of the power line towers, induced by the strong electromagnetic and electric fields of the energized power lines. The intensity and direction of those currents were measured, indicating substantial values of both their AC and DC components. The potential of the tower ground system, measured in the perpendicular direction of the main axis of the power line, was plotted as a function of the distance to the tower base. The results clearly indicated the tendency to corrosive attack in the anodic towers as reflected by the slope of the plot, whereas no signs of corrosion could be found in the reverse slope, confirming the visual inspection of the foundation. The profile of the potential plots could be changed providing the electric insulation of the lightning rod cable.
Con el crecimiento de varias áreas en la sociedad moderna, la necesidad de generar y conducir la energía eléctrica a las grandes ciudades ha aumentado enormemente. La energía, normalmente, se transporta por cables sostenidos por torres de energía con base de acero galvanizado. Cuando las bases son subterráneas, pueden ocasionar altas tasas de corrosión. Estas, normalmente, se detectan por la medida convencional del potencial empleando un electrodo de referencia de Cu/CuSO4. Se cree que la corrosión es el resultado de corrientes perdidas que fluyen a través de la
11. Assessment of rock bolt systems for underground waste storage
A review of existing rock bolting systems was undertaken to assess their suitability in underground design for storage of nuclear waste. Unique engineering considerations are required due to the thermal pulse generated by the waste causing additional stress to the support system and possibly affecting anchorage stability. Field visits were made to four underground projects to assess the performance of a wide variety of rock bolt systems. Cable bolts, point anchor bolts, locally debonded full column cement grout bolts, and yieldable bolt systems show promise. Full scale testing of bolt systems is recommended, together with assessing temperature effects on grout strength and grout longterm stability
12. Cable networks, services, and management
2015-01-01
Cable Networks, Services, and Management is the first book to cover cable networks, services, and their management, in-depth, for network operators, engineers, researchers, and students. Thirteen experts in various fields have contributed their knowledge of network architectures and services, Operations, Administration, Maintenance, Provisioning, Troubleshooting (OAMPT) for residential and business services, cloud, Software Defined Networks (SDN), as well as virtualization concepts and their applications as part of the future directions of cable networks. The book begins by introducing architecture and services for Data Over Cable Service Interface Specification (DOCSIS) 3.0/ 3.1, Converged Cable Access Platform (CCAP), Content Distribution Networks (CDN, IP TV, and Packet Cable and Wi-Fi for Residential Services. Topics that are discussed in proceeding chapters include: operational systems and management architectures, service orders, provisioning, fault manageme t, performance management, billing systems a...
13. 14 CFR 23.689 - Cable systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cable systems. 23.689 Section 23.689... Systems § 23.689 Cable systems. (a) Each cable, cable fitting, turnbuckle, splice, and pulley used must... primary control systems; (2) Each cable system must be designed so that there will be no hazardous...
14. Current distribution among layers of single phase HTS cable conductor
Highlights: • A 1.5 m long HTS model cable with 4 layers designed by the uniform current principle has been built. • It is testified that the current distribution is influenced by the proximity effect. • The magnetic flux density and current density have been analyzed. • AC losses of tested current are larger than those of uniform current. - Abstract: High temperature superconducting (HTS) power cable shows high application prospect in modern power transmission, as it is superior over conventional transmission lines in high engineering current density and environmental friendliness. Its configuration is generally composed of several HTS layers designed with the principle of uniform current distribution, but there are few experimental results to verify the distribution. In this paper, a HTS cable model was designed based on the principle of uniform current, and the current distributions among layers in an HTS cable model were measured by Rogowski coils. The results provide an important basis for design of multi-layer HTS cable
15. Cable Bacteria in Freshwater Sediments
Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus B.; Dittmer, Anders Lindequist; Bjerg, Jesper Tataru; Trojan, Daniela; Schreiber, Lars; Damgaard, Lars Riis; Schramm, Andreas; Nielsen, Lars Peter
2015-01-01
In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the fre...
16. High-temperature superconducting conductors and cables
This is the final report of a 3-year LDRD project at LANL. High-temperature superconductivity (HTS) promises more efficient and powerful electrical devices such as motors, generators, and power transmission cables; however this depends on developing HTS conductors that sustain high current densities Jc in high magnetic fields at temperatures near liq. N2's bp. Our early work concentrated on Cu oxides but at present, long wire and tape conductors can be best made from BSCCO compounds with high Jc at low temperatures, but which are degraded severely at temperatures of interest. This problem is associated with thermally activated motion of magnetic flux lines in BSCCO. Reducing these dc losses at higher temperatures will require a high density of microscopic defects that will pin flux lines and inhibit their motion. Recently it was shown that optimum defects can be produced by small tracks formed by passage of energetic heavy ions. Such defects result when Bi is bombarded with high energy protons. The longer range of protons in matter suggests the possibility of application to tape conductors. AC losses are a major limitation in many applications of superconductivity such as power transmission. The improved pinning of flux lines reduces ac losses, but optimization also involves other factors. Measuring and characterizing these losses with respect to material parameters and conductor design is essential to successful development of ac devices
17. Simplified formulae for the estimation of the positive-sequence resistance and reactance of three-phase cables for different frequencies
Silva, Filipe Miguel Faria da
2015-01-01
The installation of HVAC underground cables became more common in recent years, a trend expected to continue in the future. Underground cables are more complex than overhead lines and the calculation of their resistance and reactance can be challenging and time consuming for frequencies that are...... not power frequency. Software packages capable of performing exact calculations of these two parameters exist, but simple equations able to estimate the reactance and resistance of an underground cable for the frequencies associated to a transient or a resonance phenomenon would be helpful. This paper...... proposes new simplified formulae capable of calculating the positive-sequence resistance and reactance of a cable for frequencies associated to temporary overvoltages, slow-front overvoltages and resonance phenomena. The calculation of a cable’s resistance and reactance is made using a simplified series...
18. LOCA testing of damaged cables
Experiments were conducted to assess the effects of dielectric withstand voltage testing of cables and to assess the survivability of aged and damaged cables under loss-of-coolant accident (LOCA) conditions. High potential testing at 240 Vdc/mil on undamaged cables suggested that no damage was incurred on the selected cables. During aging and LOCA testing, Okonite ethylene propylene rubber cables with a bonded jacket experienced unexpected failures. The failures appear to be primarily related to the level of thermal aging. For Brand Rex crosslinked polyolefin cables, the results suggest that 8 mils of insulation remaining should give the cables a high probability of surviving accident exposure following aging. The voltage levels necessary to detect when 8 mils of insulation remain are expected to be roughly 40 kVdc. This voltage level would almost certainly be unacceptable to a utility for use as a damage assessment tool. Although two Rockbestos silicone rubber cables failed during the accident test, the induced wall thickness did not seem to be the major cause of the failures. It appears likely that under less stressful thermal aging conditions, the cables would survive accident testing with as little as 4 mils or less of insulation remaining
19. Superconducting flat tape cable magnet
Takayasu, Makoto
2015-08-11
A method for winding a coil magnet with the stacked tape cables, and a coil so wound. The winding process is controlled and various shape coils can be wound by twisting about the longitudinal axis of the cable and bending following the easy bend direction during winding, so that sharp local bending can be obtained by adjusting the twist pitch. Stack-tape cable is twisted while being wound, instead of being twisted in a straight configuration and then wound. In certain embodiments, the straight length should be half of the cable twist-pitch or a multiple of it.
20. Soil scientific supervision of 220/38 kV cable circuits of the power station 'Eemscentrale' in the Dutch province Groningen: Part 2
Recently, five underground cable circuits were completed at the site of the EPON (an energy utility for the north-eastern part of the Netherlands) title power station, consisting of two 220 kV and two 380 kV connections with a total length of 24 km. In a previous article, attention is paid to theoretical aspects of heat transfer of cables for underground electricity transport, the research method of the soil scientific survey, and the results of the survey for the design of the cable connection, to be made by NKF (cable manufacturer) and for the final execution of the cable design. In this article attention will be paid to soil scientific marginal conditions and soil scientific supervision during the realization. 1 fig., 2 tabs., 2 refs
1. Cable tray fire tests
Funds were authorized by the Nuclear Regulatory Commission to provide data needed for confirmation of the suitability of current design standards and regulatory guides for fire protection and control in water reactor power plants. The activities of this program through August 1978 are summarized. A survey of industry to determine current design practices and a screening test to select two cable constructions which were used in small scale and full scale testing are described. Both small and full scale tests to assess the adequacy of fire retardant coatings and full scale tests on fire shields to determine their effectiveness are outlined
2. Design of Underground Current Detection Nodes Based on ZigBee
Wei Deyu
2015-01-01
Full Text Available At present, most current detection devices of underground power equipment in coal mines of China are equipped with the cable monitoring network. Certain problems such as difficult circuit extension and maintenance exist there. With the help of ZigBee technology, it is able to monitor the underground current of monitoring regions in coal mines safely and effectively. Major advantages include extremely low system cost, safe data transmission, flexible networking and ultra-large network capacity.
3. Comparison of Bergeron and Frequency-dependent cable models for the simulation of electromagnetic transients
Silva, Filipe Miguel Faria da
2016-01-01
The simulation of electromagnetic transients involving underground cables is very time consuming, when compared with simulations involving overhead lines, and Bergeron models are often used instead of the more accurate frequency-dependent models, in order to reduce the simulation time. This paper...... analyses the simulation errors of different Bergeron models to a reference frequency-dependent model for a 150kV cable. The simulations consider flat and trefoil installation, both-ends bonding and cross-bonding, ideal voltage source and modelling of the area around the cable. The Bergeron model is...... modelling of the area around the cable being energised, the Bergeron model has a small error if tuned for the right frequency....
4. Risk assessment of 170 kV GIS connected to combined cable/OHL network
Bak, Claus Leth; Kessel, Jakob; Atlason, Vidir;
2009-01-01
This paper concerns different investigations of lightning simulation of a combined 170 kV overhead line/cable connected GIS. This is interesting due to the increasing amount of underground cables and GIS in the Danish transmission system. This creates a different system with respect to lightning...... BFO. Overvoltages are evaluated for varying front times of the lightning surge, different soil resistivities at the surge arrester grounding in the overhead line/cable transition point and a varying length of the connection cable between the transformer and the GIS busbar with a SA implemented...... inadmissible voltages to appear at the transformer. However, BFO caused by a lightning stroke of extremely high magnitude can cause inadmissible voltages to appear at the transformer. With the GIS bus CB in open position results indicate that both SF and BFO can cause inadmissible voltages to appear at the...
5. Lightning simulation of a combined overhead line/cable connected GIS
Kessel, Jakob; Atlason, Vioir; Bak, Claus Leth;
2008-01-01
The paper concerns different investigations of lightning simulation of a combined 170 kV overhead line/cable connected GIS. This is interesting due to the increasing amount of underground cables and GIS in the Danish transmission system. This creates a different system with respect to lightning...... implementing a simulation model in PSCAD/EMTDC. Simulations are conducted for both SF and BFO where the overvoltage at the transformer are evaluated as this component has the lowest insulation strength. The overvoltages are evaluated for different front imes of the lightning surge, different soil resistivities...... at the surge arrester grounding in the overhead line/cable transition and different length of the connection cable between the transformer and the GIS busbar with a SA implemented. Those simulations are conducted for different positions of the circuit breaker present at the GIS busbar. The lightning...
6. Blasting in underground mining
Doneva, Nikolinka; Despodov, Zoran; Mirakovski, Dejan; Hadzi-Nikolova, Marija; Mijalkovski, Stojance
2015-01-01
The long history of underground facilities gives us a lot of cognitions that we use in the choice of appropriate drilling and blasting parameters to obtain satisfactory results in underground facility constructions. In this paper are represent parts of those cognitions. Selection of an appropriate blast hole pattern, hole cut type, total quantity of explosives, initiation sequence and to the amount of explosive detonated per delay are crucial for successfully blasting in underground facilitie...
7. The underground storage
In this work are given summaries of the addresses presented at the conference on the underground storage of June 2008. The topics described are: 1)sites and legislation of the underground storage in France (Carole Mercier) 2)oil and gas underground storage in salt cavities (Patrick Renoux) 3) geothermal storages (Herve Lesueur) 4)CO2 geological storage in aquifers and exploited oil deposits (Etienne Brosse). (O.M.)
8. Underground laboratories in Asia
Deep underground laboratories in Asia have been making huge progress recently because underground sites provide unique opportunities to explore the rare-event phenomena for the study of dark matter searches, neutrino physics and nuclear astrophysics as well as the multi-disciplinary researches based on the low radioactive environments. The status and perspectives of Kamioda underground observatories in Japan, the existing Y2L and the planned CUP in Korea, India-based Neutrino Observatory (INO) in India and China JinPing Underground Laboratory (CJPL) in China will be surveyed
9. Underground laboratories in Asia
Lin, Shin Ted, E-mail: [email protected] [College of Physical Science and Technology, Sichuan University, Chengdu 610064 China (China); Yue, Qian, E-mail: [email protected] [Key Laboratory of Particle and Radiation Imaging (Ministry of Education) and Department of Engineering Physics, Tsinghua University, Beijing 100084 China (China)
2015-08-17
Deep underground laboratories in Asia have been making huge progress recently because underground sites provide unique opportunities to explore the rare-event phenomena for the study of dark matter searches, neutrino physics and nuclear astrophysics as well as the multi-disciplinary researches based on the low radioactive environments. The status and perspectives of Kamioda underground observatories in Japan, the existing Y2L and the planned CUP in Korea, India-based Neutrino Observatory (INO) in India and China JinPing Underground Laboratory (CJPL) in China will be surveyed.
10. Test results of full-scale high temperature superconductors cable models destined for a 36 kV, 2 kA(rms) utility demonstration
Daumling, M.; Rasmussen, C.N.; Hansen, F.;
2001-01-01
Power cable systems using high temperature superconductors (HTS) are nearing technical feasibility. This presentation summarises the advancements and status of a project aimed at demonstrating a 36 kV, 2 kA(rms) AC cable system by installing a 30 m long full-scale functional model in a power util...
11. Cable Bacteria in Freshwater Sediments
Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus;
2015-01-01
In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures and...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...
12. Electromagnetic Transients in Power Cables
Silva, Filipe Faria Da; Bak, Claus Leth
For more than a century, overhead lines have been the most commonly used technology for transmitting electrical energy at all voltage levels, especially on the highest levels. However, in recent years, an increase in both the number and length of HVAC cables in the transmission networks...... concerning HVAC cables. An important topic that is not covered in this book is measurements protocols/ methods. The protocols used when performing measurements on a cable depend on what is to be measured, the available equipment and accessibility. Readers interested in the topic are referred to search...... of the method. The chapter continues by analysing the frequency-spectrums of cable-based networks which have lower resonance frequencies than usual because of the larger capacitance of the cables. At the same time, a technique that may help save time when plotting the frequency spectrum of a network is proposed...
13. Length of a Hanging Cable
Eric Costello
2011-01-01
Full Text Available The shape of a cable hanging under its own weight and uniform horizontal tension between two power poles is a catenary. The catenary is a curve which has an equation defined by a hyperbolic cosine function and a scaling factor. The scaling factor for power cables hanging under their own weight is equal to the horizontal tension on the cable divided by the weight of the cable. Both of these values are unknown for this problem. Newton's method was used to approximate the scaling factor and the arc length function to determine the length of the cable. A script was written using the Python programming language in order to quickly perform several iterations of Newton's method to get a good approximation for the scaling factor.
14. Numerical Analysis of Heat Transfer and Fluid Characteristics of Flowing Liquid Nitrogen in HTS Cable
Maruyama, O.; Ohkuma, T.; Izumi, T.; Shiohara, Y.
High-temperature superconducting (HTS) cable has heat intrusion from the termination including joule heat generation at the terminal joint and from the room temperature cable through the Cu current lead. According to the length of the HTS cable, this heat loss may become a considerable amount which cannot be ignored in the HTS cable system. In this study, referring to a high-voltage cable (HV cable) which was developed in M-PACC project, the effect of heat transfer at the interface between the terminal joint and LN2 in the terminal vessel (ho) on the temperature of the HTS cable were calculated and evaluated. The condition of flow in the terminal vessel was assumed to be natural convection, forced flow or static condition for evaluating this effect with various heat transfer condition. As a result, in the case of the natural convection, most of heats flow into the LN2 in the terminal vessel where the volumetric flow of the LN2 is large since ho becomes high. Accordingly, the temperature rise of the LN2 in the inner pipe of Cu former and the terminal vessel can be restricted. However, in the cases of the forced flow and the static condition, most of heats flow into the LN2 in the inner pipe where the volumetric flow of the LN2 is small since ho becomes small. Accordingly, the temperature rise of the LN2 in the inner pipe becomes high. This temperature rise of the LN2 in the inner pipe makes the temperature of the HTS conductor large resulting in remarkable increase of AC losses. Consequently, on the HV cable design, for restriction of the AC loss increase, it is expected that designing the HTS cable termination such as extending outer surface of the terminal joint for increasing of the heat inflow from the terminal joint to the LN2 in the vessel is effective.
15. Status and Progress of a Fault Current Limiting Hts Cable to BE Installed in the con EDISON Grid
Maguire, J.; Folts, D.; Yuan, J.; Henderson, N.; Lindsay, D.; Knoll, D.; Rey, C.; Duckworth, R.; Gouge, M.; Wolff, Z.; Kurtz, S.
2010-04-01
In the last decade, significant advances in the performance of second generation (2G) high temperature superconducting wire have made it suitable for commercially viable applications such as electric power cables and fault current limiters. Currently, the U.S. Department of Homeland Security is co-funding the design, development and demonstration of an inherently fault current limiting HTS cable under the Hydra project with American Superconductor and Consolidated Edison. The cable will be approximately 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The underground cable will be installed and energized in New York City. The project is led by American Superconductor teamed with Con Edison, Ultera (Southwire and nkt cables joint venture), and Air Liquide. This paper describes the general goals, design criteria, status and progress of the project. Fault current limiting has already been demonstrated in 3 m prototype cables, and test results on a 25 m three-phase cable will be presented. An overview of the concept of a fault current limiting cable and the system advantages of this unique type of cable will be described.
16. Parametric study on the axial performance of a fully grouted cable bolt with a new pull-out test
Chen Jianhang⇑; Hagan Paul C.; Saydam Serkan
2016-01-01
Modified cable bolts are commonly used in underground mines due to their superior performance in pre-venting bed separation when compared with plain strands. To better test the axial performance of a wide range of cable bolts, a new laboratory short encapsulation pull test (LSEPT) facility was developed. The facility simulates the interaction between cable bolts and surrounding rock mass, using artificial rock cylinders with a diameter of 300 mm in which the cable bolt is grouted. Furthermore, the joint where the load is applied is left unconstrained to allow shear slippage at the cable/grout or grout/rock interface. Based on this apparatus, a series of pull tests were undertaken using the MW9 modified bulb cable bolt. Various parameters including embedment length, test material strength and borehole size were evalu-ated. It was found that within a limited range of 360 mm, there is a linear relationship between the max-imum bearing capacity of the cable bolt and embedment length. Beyond 360 mm, the peak capacity continues to rise but with a much lower slope. When the MW9 cable bolt was grouted in a weak test material, failure always took place along the grout/rock interface. Interestingly, increasing the borehole diameter from 42 to 52 m in weak test material altered the failure mode from grout/rock interface to cable/grout interface and improved the performance in terms of both peak and residual capacity.
17. 400 MW grid connection to the Anholt offshore wind farm in a single 220 kV cable system
Kvarts, Thomas [Energinet.dk (Denmark); Bailleul, March; Douima, Youssef; Petitot, Francois [General Cable Group, Silec, Cachan (France); Domingo, Jose M. [General Cable Group (Spain); Jensen, Anders; Salwin, Sven T. [nkt cables (Denmark)
2011-07-01
In 2012, the so far largest wind farm in Denmark, Anholt offshore wind farm, will bring 400 MW more electrical power to Denmark. To that effect, Energinet.dk, Denmark's transmission system operator, will install and operate an 85-km-long grid connection from the Anholt platform to the Danish electricity transmission grid. This connection is composed of: (1) a single 24 km 245 kV submarine, 3 core cable, delivered and installed by nkt cables, and (2) a 60 km 245 kV underground cable system, delivered by the General Cable group. (3) an offshore transformer platform. (4) reactive compensation and transformation onshore. This aim of this paper is to present the characteristics of this project, the first at 245 kV in Denmark, and one of the first 245 kV 3 core submarine cables worldwide. We will first discuss the reasons that prevailed in defining the link's design: routes, voltage, cables dimensioning, impact of capitalized losses etc. Then, the submarine and underground cable systems' characteristics and necessary type test are presented. Finally, we present an overview of the actual implementation of each solution. (orig.)
18. Roebel cables from REBCO coated conductors: a one-century-old concept for the superconductivity of the future
Energy applications employing high-temperature superconductors (HTS), such as motors/generators, transformers, transmission lines and fault current limiters, are usually operated in the alternate current (ac) regime. In order to be efficient, the HTS devices need to have a sufficiently low value of ac loss, in addition to the necessary current-carrying capacity. Most applications are operated with currents beyond the current capacity of single conductors and consequently require cabled conductor solutions with much higher current carrying capacity, from a few kA up to 20–30 kA for large hydro-generators. A century ago, in 1914, Ludwig Roebel invented a low-loss cable design for copper cables, which was successively named after him. The main idea behind Roebel cables is to separate the current in different strands and to provide a full transposition of the strands along the cable direction. Nowadays, these cables are commonly used in the stator of large generators. Based on the same design concept of their conventional material counterparts, HTS Roebel cables from REBCO coated conductors were first manufactured at the Karlsruhe Institute of Technology and have been successively developed in a number of varieties that provide all the required technical features such as fully transposed strands, high transport currents and low ac losses, yet retaining enough flexibility for a specific cable design. In the past few years a large number of scientific papers have been published on the concept, manufacturing and characterization of such cables. Therefore it is timely for a review of those results. The goal is to provide an overview and a succinct and easy-to-consult guide for users, developers, and manufacturers of this kind of HTS cable. (topical review)
19. Roebel cables from REBCO coated conductors: a one-century-old concept for the superconductivity of the future
Goldacker, Wilfried; Grilli, Francesco; Pardo, Enric; Kario, Anna; Schlachter, Sonja I.; Vojenčiak, Michal
2014-09-01
Energy applications employing high-temperature superconductors (HTS), such as motors/generators, transformers, transmission lines and fault current limiters, are usually operated in the alternate current (ac) regime. In order to be efficient, the HTS devices need to have a sufficiently low value of ac loss, in addition to the necessary current-carrying capacity. Most applications are operated with currents beyond the current capacity of single conductors and consequently require cabled conductor solutions with much higher current carrying capacity, from a few kA up to 20-30 kA for large hydro-generators. A century ago, in 1914, Ludwig Roebel invented a low-loss cable design for copper cables, which was successively named after him. The main idea behind Roebel cables is to separate the current in different strands and to provide a full transposition of the strands along the cable direction. Nowadays, these cables are commonly used in the stator of large generators. Based on the same design concept of their conventional material counterparts, HTS Roebel cables from REBCO coated conductors were first manufactured at the Karlsruhe Institute of Technology and have been successively developed in a number of varieties that provide all the required technical features such as fully transposed strands, high transport currents and low ac losses, yet retaining enough flexibility for a specific cable design. In the past few years a large number of scientific papers have been published on the concept, manufacturing and characterization of such cables. Therefore it is timely for a review of those results. The goal is to provide an overview and a succinct and easy-to-consult guide for users, developers, and manufacturers of this kind of HTS cable.
20. HAWAII UNDERGROUND STORAGE TANKS
This is a point coverage of underground storage tanks(UST) for the state of Hawaii. The original database was developed and is maintained by the State of Hawaii, Dept. of Health. The point locations represent facilities where one or more underground storage tanks occur. Each fa...
1. Cable Aerodynamic Control
Kleissl, Kenneth
categorization of the different control technics together with an identification of two key mechanisms for reduction of the design drag force. During this project extensive experimental work examining the aerodynamics of the currently used cable surface modifications together with new innovative proposals have...... drag force due to the high intensity of streamwise vorticity, whereas the helical fillets resulted in a more gradual flow transition because of the spanwise variation. During yawed flow conditions, the asymmetrical appearance of the helical solution was found to induce a significant lift force with a...... were tested. While a proper discrete helical arrangement of Cylindrical Vortex Generators resulted in a superior drag performance, only systems applying "mini-strakes" were capable of complete rivulet suppression. When the strakes was positioned in a staggered helical arrangement, the innovative system...
2. Cable Bacteria in Freshwater Sediments.
Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus B; Dittmer, Anders Lindequist; Bjerg, Jesper Tataru; Trojan, Daniela; Schreiber, Lars; Damgaard, Lars Riis; Schramm, Andreas; Nielsen, Lars Peter
2015-09-01
In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures and electric fields indicated electron transfer between vertically separated anodic and cathodic half-reactions. Fluorescence in situ hybridization revealed the presence of Desulfobulbaceae filaments. In addition, in situ measurements of oxygen, pH, and electric potential distributions in the waterlogged banks of Giber Å demonstrated the presence of distant electric redox coupling in naturally occurring freshwater sediment. At the same site, filamentous Desulfobulbaceae with cable bacterium morphology were found to be present. Their 16S rRNA gene sequence placed them as a distinct sister group to the known marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary origin of the cable phenotype within Desulfobulbaceae with subsequent diversification into a freshwater and a marine lineage. PMID:26116678
3. Recent development of an HTS power cable using YBCO tapes
Overcurrent characteristics and reduction of AC loss are essential for high temperature superconducting (HTS) cable in a real grid. AC loss in an HTS conductor using YBCO could be potentially small but protection for overcurrent was needed. A 0.1 mm thick copper tape soldered to the YBCO tape was effective as protection from overcurrent and did not affect the increase in AC loss. The 2 m HTS conductor with Cu strands of 250 mm2 and YBCO tapes with copper was fabricated. This conductor could withstand overcurrent of 31.5 kA for 2 s. To reduce AC loss, 10 mm wide YBCO tapes were divided into five strips using YAG laser. Using narrower strips and decreasing the space between the strips were effective in reducing AC loss. In consideration of this configuration, a three-layer conductor was fabricated, and AC loss of 0.054 W/m at 1 kA rms was achieved even though it had a small outer diameter of 19.6 mm
4. Investigation of mechanism of breakdown in XLPE cables. Final report
McKean, A.L.
1976-07-01
The basic hypothesis that microporosity plays a significant role in the mechanism of breakdown of XLPE cable is explored. The potential improvement achieved by impregnating the microporous regions of the cable core with a neutral liquid is evaluated, with relation to ac voltage life and impulse strength. The effect at higher frequency is also demonstrated. A similar test program is pursued on model cables, designed to explore the effects of gas pressure and gas type on breakdown and life, since it is reasonable to expect that only the microporous regions of the insulation should be sensitive to the gas-pressure environment. Comparison of gas-pressurized model breakdown stress (and related microvoid size) with basic Paschen curves demonstrates reasonably good agreement, indicating that partial discharge is the basic mechanism of fatigue and breakdown. The form of the voltage life curve above and below the discharge inception level is proposed, and evidence is presented indicating breakdown originates in the bulk insulation as well as at the shield interface. It is also shown that model cable discharge energies are below 0.1 pC, even at very high stress, and cannot be measured with modern detectors. Results with liquid or gas impregnation suggest a possible approach to dielectric improvement.
5. Magnetization Losses of Roebel Cable Samples with 2G YBCO Coated Conductor Strands
Yang, Y.; Falorio, I.; Young, E.A.; Kario, A.; Goldacker, W.; Dhallé, M. M. J.; van Nugteren, J.; Kirby, G.; Bottura, L.; Ballarino, A.; 10.1109/TASC.2016.2525926
2016-01-01
Roebel cable with 2G YBCO strands is one of the promising HTS solutions of fully transposed high current conductors for high field accelerator magnets. Following the considerable research effort on the manufacturing of Roebel cables in recent years, sample conductors are now available in useful lengths with reproducible performances to allow detailed characterizations beyond the standard critical current measurements. The ac loss and strands coupling are of significant interest for the field quality of the accelerator magnets. We report a set of systematic ac loss measurements on two different Roebel cable samples prepared for the EuCARD2 collaboration. The measurements were performed over a wide range of temperature between 5 K and 90 K and the results were analyzed in the context of strands architecture and coupling. The results show that the transposed bundles are partially decoupled and the strands in transposition sections behave as an isolated single tape if the strands are insulated.
6. A full 3D time-dependent electromagnetic model for Roebel cables
Rodriguez Zermeno, Victor Manuel; Grilli, Francesco; Sirois, Frederic
2013-01-01
High temperature superconductor Roebel cables are well known for their large current capacity and low AC losses. For this reason they have become attractive candidates for many power applications. The continuous transposition of their strands reduces the coupling losses while ensuring better curr...
7. Analysis of AC loss in superconducting power devices calculated from short sample data
Rabbers, J.J.; Haken, ten B.; Kate, ten H.H.J.
2003-01-01
A method to calculate the AC loss of superconducting power devices from the measured AC loss of a short sample is developed. In coils and cables the magnetic field varies spatially. The position dependent field vector is calculated assuming a homogeneous current distribution. From this field profile
8. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.
Litzenberger, Wayne; Lava, Val
1994-08-01
References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).
9. 一体式电缆井的使用%Use of Integrated Cable Pit
蒋彦; 韦玮; 谈东波
2012-01-01
通过分析现有室外电缆井施工存在的不足，提出预制一体式电缆井的解决方案。分析一体式电缆井的技术优势、施工方法和注意事项，说明一体式电缆井的可实施性和推广价值。%Ac cording to the analysis on the disadvantages of construction of existing outdoor cable pits, a solution for prefabricated integrated cable pits is proposed. The technical advantages, construction methods and precautions of integrated cable pits are analyzed, and the practicality and promotion value of integrated cable pits is explained
10. On the cable expansion formula
Liu, Qihou
2008-01-01
In this paper, a generalized version of Morton's formula is proved. Using this formula, one can write down the colored Jones polynomials of cabling of an knot in terms of the colored Jones polynomials of the original knot.
11. Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables
Xu Xie
2014-06-01
Full Text Available In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.
12. Alternating current losses of a 10 metre long low loss superconducting cable conductor determined from phase sensitive measurements
Olsen, Søren Krüger; Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten;
1999-01-01
The ac loss of a superconducting cable conductor carrying an ac current is small. Therefore the ratio between the inductive (out-of-phase) and the resistive (in-phase) voltages over the conductor is correspondingly high. In vectorial representations this results in phase angles between the current...... and the voltage over the cable close to 90 degrees. This has the effect that the loss cannot be derived directly using most commercial lock-in amplifiers due to their limited absolute accuracy. However, by using two lock-in amplifiers and an appropriate correction scheme the high relative accuracy of...... such lock-in amplifiers can be exploited. In this paper we present the results from ac-loss measurements on a low loss 10 metre long high temperature superconducting cable conductor using such a correction scheme. Measurements were carried out with and without a compensation circuit that could reduce...
13. The underground macroeconomics
Marin Dinu
2013-01-01
Full Text Available Like Physics, which cannot yet explain 96% of the substance in the Universe, so is Economics, unprepared to understand and to offer a rational explicative model to the underground economy.
14. Orpheus in the Underground
Puskás Dániel
2015-12-01
Full Text Available In my study I deal with descents to the underworld and hell in literature in the 20th century and in contemporary literature. I will focus on modem literary reinterpretations of the myth of Orpheus, starting with Rilke’s Orpheus. Eurydice. Hermes. In Seamus Heaney’s The Underground. in the Hungarian Istvan Baka’s Descending to the Underground of Moscow and in Czesław Miłosz’s Orpheus and Eurydice underworld appears as underground, similarly to the contemporary Hungarian János Térey’s play entitled Jeramiah. where underground will also be a metaphorical underworld which is populated with the ghosts of the famous deceased people of Debrecen, and finally, in Péter Kárpáti’s Everywoman the grave of the final scene of the medieval Everyman will be replaced with a contemporary underground station. I analyse how an underground station could be parallel with the underworld and I deal with the role of musicality and sounds in the literary works based on the myth of Orpheus.
15. Parametric Vibration and Vibration Reduction of Cables in Cable-stayed Space Latticed Structure
BAO Yan; ZHOU Dai; LIU Jie
2008-01-01
Mechanical model and vibration equation of a cable in cable-stayed sparse latticed structure (CSLS) under external axial excitation were founded. Determination of the mass lumps and natural frequencies supplied by the space latticed structure (SLS) was analyzed. Multiple scales method (MSM) was introduced to analyze the characteristics of cable's parametric vibration, and the precise time-integration method (PTIM) was used to solve vibration equation. The vibration behavior of a cable is closely relative to the frequency ratio of the cable and SLS. The cable's parametric vibration caused by the external axial excitation easily occurs if the frequency ratio of the cable and SLS is in a certain range, and the cable's vibration amplitude varies greatly even if the initial disturbance supplied by SLS changes a little. Furthermore, the mechanical model and vibration equation of the composite cable system consisting of main cables and assistant cables were studied. The parametric analysis such as the pre-tension level and arrangement of the assistant cables was carried out. Due to the assistant cables, the single-cable vibration mode can be transferred to the global vibration mode, and the stiffness and damping of the cable system are enhanced. The natural frequencies of the composite cable system with the curve line arrangement of assistant cables are higher than those with the straight-line arrangement and the former is more effective than the latter on the cable's vibration suppression.
16. Flat conductor cable design, manufacture, and installation
Angele, W.; Hankins, J. D.
1973-01-01
Pertinent information for hardware selection, design, manufacture, and quality control necessary for flat conductor cable interconnecting harness application is presented. Comparisons are made between round wire cable and flat conductor cable. The flat conductor cable interconnecting harness systems show major cost, weight, and space savings, plus increased system performance and reliability. The design application section includes electrical characteristics, harness design and development, and a full treatise on EMC considerations. Manufacturing and quality control sections pertain primarily to the developed conductor-contact connector system and special flat conductor cable to round wire cable transitions.
17. Optical Measurement of Cable and String Vibration
Y. Achkire
1998-01-01
Full Text Available This paper describes a non contacting measurement technique for the transverse vibration of small cables and strings using an analog position sensing detector. On the one hand, the sensor is used to monitor the cable vibrations of a small scale mock-up of a cable structure in order to validate the nonlinear cable dynamics model. On the other hand, the optical sensor is used to evaluate the performance of an active tendon control algorithm with guaranteed stability properties. It is demonstrated experimentally, that a force feedback control law based on a collocated force sensor measuring the tension in the cable is feasible and provides active damping in the cable.
18. Numerical estimation of AC loss in superconductors with ripple current
Highlights: •The loss energy density with ripple current is numerically calculated. •Irie–Yamafuji model is used for magnetic field dependence of critical current. •Calculated result of cylindrical superconductor agrees with theoretical result. •AC loss of strip superconductor becomes large at small ripple current amplitude. •Strip superconductor should be used as a form of hollow cylinder to reduce AC loss. -- Abstract: The loss energy density (AC loss) with ripple current is numerically calculated by finite element method for cylindrical and strip superconductors based on Irie–Yamafuji model in which the magnetic field dependence of the critical current density is taken into account for design of DC transmission cable system. It is confirmed that calculated result of the AC loss in the cylindrical superconductor with the ripple current agrees well with theoretical estimation which was reported in the previous work. On the contrary, the AC loss in the strip superconductor with the ripple current is obtained only by numerical calculation. It is found that the AC loss in the strip superconductor of the ripple current becomes larger than that without DC current at small ripple current amplitude, since the penetration depth of magnetic field becomes large. Therefore, it is recommended that strip superconductor is better to use as cylindrical hollow superconductor for DC transmission cable system to reduce the AC loss
19. The data quality monitoring system of non-cable self-positioning seismographs
Zheng, F.; Lin, J.; Linhang, Z.; Hongyuan, Y.; Zubin, C.; Huaizhu, Z.; Sun, F.
2013-12-01
Seismic exploration is the most effective and promising geophysical exploration methods, it inverts underground geological structure by recording crust vibration caused by nature or artificial means. In order to get rid of the long-term dependence on imported seismographs, China pays more and more attention to the independent research and development of seismic exploration equipment. This study is based on the self-invented non-cable self-positioning seismographs of Jilin University. Non-cable seismographs have many advantages such as simple arrangement, light, easy to move, easy to maintain, low price, large storage space and high-quality data, they especially apply to complex terrain and field construction environment inconvenient laying big lines. The built-in integration of GPS realizes precise clock synchronization, fast and accurate self-positioning for non-cable seismographs. The low power design and the combination of built-in rechargeable battery and external power can effectively improve non-cable seismographs` working time, which ensures the stability of exploration and construction. In order to solve the problem that the non-cable seismographs are difficult to on-site data monitor and also to provide non-cable seismographs` ability of real-time data transmission, We integrate the wireless communication technology into non-cable seismographs, combing instrument, electronic, communication, computer and many other subject knowledge, design and develop seismic exploration field work control system and seismic data management system. Achieve two research objectives which are real-time data quality monitoring in the resource exploration field and status monitoring of large trace spacing long-term observations for seismographs. Through several field experiments in different regions, we accumulate a wealth of experience, and the experiments effectively prove the good practical performance of non-cable self-positioning seismographs and data quality monitoring
20. Underground physics with DUNE
Kudryavtsev, Vitaly A.; DUNE Collaboration
2016-05-01
The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40-kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well as proton decay and supernova neutrino burst searches. In this paper we will focus on the underground physics with DUNE.
1. Underground mineral extraction
Miller, C. G.; Stephens, J. B.
1980-01-01
A method was developed for extracting underground minerals such as coal, which avoids the need for sending personnel underground and which enables the mining of steeply pitched seams of the mineral. The method includes the use of a narrow vehicle which moves underground along the mineral seam and which is connected by pipes or hoses to water pumps at the surface of the Earth. The vehicle hydraulically drills pilot holes during its entrances into the seam, and then directs sideward jets at the seam during its withdrawal from each pilot hole to comminute the mineral surrounding the pilot hole and combine it with water into a slurry, so that the slurried mineral can flow to a location where a pump raises the slurry to the surface.
2. Underground physics with DUNE
Kudryavtsev, Vitaly A
2016-01-01
The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40 kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well as proton decay and supernova neutrino burst searches. In this paper we will focus on the underground physics with DUNE.
3. Underground Physics with DUNE
Kudryavtsev, Vitaly A. [Sheffield U.
2016-01-14
The Deep Underground Neutrino Experiment (DUNE) is a project to design, construct and operate a next-generation long-baseline neutrino detector with a liquid argon (LAr) target capable also of searching for proton decay and supernova neutrinos. It is a merger of previous efforts of the LBNE and LBNO collaborations, as well as other interested parties to pursue a broad programme with a staged 40 kt LAr detector at the Sanford Underground Research Facility (SURF) 1300 km from Fermilab. This programme includes studies of neutrino oscillations with a powerful neutrino beam from Fermilab, as well as proton decay and supernova neutrino burst searches. In this paper we will focus on the underground physics with DUNE.
4. Online Cable Tester and Rerouter
Lewis, Mark; Medelius, Pedro
2012-01-01
Hardware and algorithms have been developed to transfer electrical power and data connectivity safely, efficiently, and automatically from an identified damaged/defective wire in a cable to an alternate wire path. The combination of online cable testing capabilities, along with intelligent signal rerouting algorithms, allows the user to overcome the inherent difficulty of maintaining system integrity and configuration control, while autonomously rerouting signals and functions without introducing new failure modes. The incorporation of this capability will increase the reliability of systems by ensuring system availability during operations.
5. Equalization of data transmission cable
Zobrist, G. W.
1975-01-01
The paper describes an equalization approach utilizing a simple RLC network which can obtain a maximum slope of -12dB/octave for reshaping the frequency characteristics of a data transmission cable, so that data may be generated and detected at the receiver. An experimental procedure for determining equalizer design specifications using distortion analysis is presented. It was found that for lengths of 16 PEV-L cable of up to 5 miles and data transmission rates of up to 1 Mbs, the equalization scheme proposed here is sufficient for generation of the data with acceptable error rates.
6. Development of the communication cable suspending robot. Automation of cable suspending works; Tsushin cable tsurika robot no kaihatsu. Cable tsurika sagyo no jidoka
Maeda, T. [Kansai Electaric Power Co. Inc., Osaka (Japan)
2000-04-01
The automatic communication cable suspending robot was developed. For disuse of dangerous stringers and improvement of suspending workability, adoption of the new mechanical high-speed labor-saving cable laying method was decided regardless of current communication cable laying methods. This robot can deal with automatic removal works of existing cable hangers which has been thought to be extremely difficult, and thus integration works of many cables by a cable hanger in cable additional installation work. For easy handling of the robot, the robot body is composed of 6 separated parts such as driving part, power source part, cable draw-in part, hanger attaching part, hanger removing part and hanger recovering part according to each function. For avoiding troubles with telephone lines and CATV lines in city areas, the size and mass of the robot were considered enough. After this, some verification tests on the robot effectiveness including performance test, workability test on dummy poles, and field test are scheduled. (NEDO)
7. North American Submarine Cable Association (NASCA) Submarine Cables
National Oceanic and Atmospheric Administration, Department of Commerce — These data show the locations of in-service and out-of-service submarine cables that are owned by members of NASCA and located in U.S. territorial waters. More...
8. 47 CFR 76.640 - Support for unidirectional digital cable products on digital cable systems.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Support for unidirectional digital cable products on digital cable systems. 76.640 Section 76.640 Telecommunication FEDERAL COMMUNICATIONS... Standards § 76.640 Support for unidirectional digital cable products on digital cable systems. (a)...
9. Dynamic Underground Stripping Project
LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called ''Dynamic Stripping'' to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving the contaminated site in FY 92
10. Improvements in electric cable gland seals
An electric cable gland seal has a deformable sealing member which is penetrated by cables arranged in annular spaced array, the sealing member being disposed between two spreader plates which when urged together by springs compress and deform the sealing member into sealing contact with the cables, a distributor which holds the cables in the spaced array, and a cylindrical body adapted for sealing about an opening in the wall of a vessel. (UK)
11. The Application of Novel Polypropylene to the Insulation of Electric Power Cable (2)
Miyashita, Yoshitsugu; Demura, Tsuyoshi; Ueda, Asakiyo; Someya, Akira; Kawahigashi, Masaki; Murakami, Tsuyoshi; Matsuda, Yoshiji; Kurahashi, Kiyoshi; Yoshino, Katsumi
The authors had investigated the basic properties of newly developed stereoregular syndiotactic polypropylene (s-PP) which had been synthesized with homogeneous metallocene catalyst, in the previous paper. As the result of this, it was revealed that s-PP had superior thermal and electrical properties to cross-linked polyethylene (XLPE) which was adopted as conventional insulating material for high voltage power cable. In this paper, we estimated the possibility to apply s-PP to the actual power cable from the viewpoint of long-term thermal durability and processability. Consequently, it was found that the thermal stability of s-PP could be significantly improved by adding both hindered phenol and sulfur antioxidants, and wide molecular weight distribution of s-PP contributed to good processability during extrusion. On the basis of these results, 600V and 22kV class cables with insulation of s-PP were manufactured. Successfully manufactured cables proposed that s-PP could be available to electric power cable. Lightning Impulse and AC breakdown strength of both cables at the temperature range of RT to 120°C will be discussed.
12. Cable Insulation Breakdowns in the Modulator with a Switch Mode High Voltage Power Supply
Cours, A
2004-01-01
The Advanced Photon Source modulators are PFN-type pulsers with 40 kV switch mode charging power supplies (PSs). The PS and the PFN are connected to each other by 18 feet of high-voltage (HV) cable. Another HV cable connects two separate parts of the PFN. The cables are standard 75 kV x-ray cables. All four cable connectors were designed by the PS manufacturer. Both cables were operating at the same voltage level (about 35 kV). The PSs output connector has never failed during five years of operation. One of the other three connectors failed approximately five times more often than the others. In order to resolve the failure problem, a transient analysis was performed for all connectors. It was found that transient voltage in the connector that failed most often was subjected to more high-frequency, high-amplitude AC components than the other three connectors. It was thought that these components caused partial discharge in the connector insulation and led to the insulation breakdown. Modification o...
13. Your Personal Genie in the Cable.
Schlafly, Hubert J.
The technology necessary for the use of cable television (TV) has been invented; it simply must be put to use. By the 1970's, cable TV should be commonplace in this country. Its rapid growth was caused in part by its appearance at a time of explosive expansion of related technologies like data theory and computer design. The coaxial cable system…
14. EMP coupling to multiconductor shielded cables
A method is presented for calculating EMP coupling to multiconductor shielded cables by electromagnetic pulse. The induced voltage of inner conductor of the SYV-50-7 cable and SYVZ-9 cable placed on the ground are computed. The computed results agree with those measured
15. Using Cable Television for Library Data Transmission.
Whitaker, Douglas A.
1985-01-01
Discusses information gained from a test of cable data circuits on a Geac bibliographic control system at the Wayne Oakland Library Federation (WOLF) (Michigan). Highlights include an introduction to cable, hardware profile, the WOLF experience, and key questions that will affect the future use of cable for data transmission. (EJS)
16. Evaluation of AC losses for HT-7U CICC on plasma disruption
AC loss is one of the main issues in the design of the CICC used for PF and TF coils of superconducting tokamak. A preliminary calculation of AC loss for the designed HT-7U CICCs used for TF magnets is given. The authors only consider the hysteresis and coupling losses related to transversal and longitudinal kinds. In addition to the strand resistive barriers (Pb-30Sn-2Sb coating for NbTi strands), a stainless steel strip has been used inside these cables to reduce the AC loss in this kind of conductor. The available theory has enabled to emphasize the role played by the stainless steel strip in the reduction of total AC losses in this kind of conductor. It was shown that AC losses of cable were affected by the structure and change rate of magnetic field
17. Underground Storage Tanks in Iowa
Iowa State University GIS Support and Research Facility — Underground storage tank (UST) sites which store petroleum in Iowa. Includes sites which have been reported to DNR, and have active or removed underground storage...
18. Raman distributed temperature sensing in underground geoexchange system
Giuseffi, Marie; Ferdinand, Pierre; Vrain, Alexandre; Philippe, Mikael; Lesueur, Hervé
2010-09-01
Underground heat exchangers are instrumented by eight multimode optical fiber cables connected to a distributed temperature sensing (DTS) Raman system which provides real time temperature monitoring, versus operational conditions of the installation. A user-friendly Labview® software has been developed, allowing the configuration of the full installation, the signal processing of raw DTS data and storage, as well as the visualization of any temperature profile, on request. Preliminary temperature profiles are very promising. This platform will allow R&D about geothermal exchanges, will provide a full scale bench to characterize new equipments, and will encourage professionals to develop this renewable energy sector.
19. ALOHA Cabled Observatory: Early Results
Howe, B. M.; Lukas, R.; Duennebier, F. K.
2011-12-01
The ALOHA Cabled Observatory (ACO) was installed 6 June 2011, extending power, network communications and timing to a seafloor node and instruments at 4726 m water depth 100 km north of Oahu. The system was installed using ROV Jason operated from the R/V Kilo Moana. Station ALOHA is the field site of the Hawaii Ocean Time-series (HOT) program that has investigated temporal dynamics in biology, physics, and chemistry since 1988. HOT conducts near monthly ship-based sampling and makes continuous observations from moored instruments to document and study climate and ecosystem variability over semi-diurnal to decadal time scales. The cabled observatory system will provide the infrastructure for continuous, interactive ocean sampling enabling new measurements as well as a new mode of ocean observing that integrates ship and cabled observations. The ACO is a prototypical example of a deep observatory system that uses a retired first-generation fiber-optic telecommunications cable. Sensors provide live video, sound from local and distant sources, and measure currents, pressure, temperature, and salinity. Preliminary results will be presented and discussed.
20. Inflation and the underground economy
Ahiabu, Stephen
2006-01-01
This paper studies the optimal rate of seigniorage in an economy characterized by decentralized trade and a tax-evading underground sector. The economy has buyers, some of whom visit the formal market, while others visit the underground market. I find that the optimal rate of inflation depends on which of the two sectors, formal or underground, is more crowded/congested with buyers. If the underground sector is more crowded, the optimal inflation rate is as high as 42% per a...
1. Underground Economy in Croatia
Marija Švec
2009-12-01
Full Text Available The subject of this paper is to estimate the size of underground economy in the period 2001-2007 using labour approach. Two types of data are used: administrative and survey. The main questions are: How did the activity rates move? What is the relationship between activity rates and the size of shadow economy? Is there correlation between official employment, official unemployment and unofficial employment (shadow economy and what is it like? What is the position of Croatia considering the members of the European Union? It is presumed that the increase of activity rates causes decrease of underground economy. However, this assumption is valid only for administrative data. Correlation analysis is based on regression models and given results are quite logical. If Croatian and European underground economy is compared, it can be confirmed that the position of Croatia is extremely poor. Given results are approximative and show the level of Croatian underground economy which is presumably underestimated. These phenomena occur because of available statistics and method limitations
2. Advanced method for cable aging evaluation
The project of 'Assessment of Cable Aging for Nuclear Power Plants' started in FY2002. Until the end of FY2006, approximately 80% of the planned aging data has been acquired by the cable aging evaluation tests. The LOCA tests for nine kinds of cables were also conducted using the simultaneous aging specimens. Based on these results, the outlines of 'Guidelines for environmental qualification test for cables (Draft)' were developed. And a tentative assessment for seven kinds of cables was made using data acquired until present according to the outlines of guidelines. (author)
3. Aeolic vibration of aerial electricity transmission cables
Avila, A.; Rodriguez-Vera, Ramon; Rayas, Juan A.; Barrientos, Bernardino
2005-02-01
A feasibility study for amplitude and frequency vibration measurement in aerial electricity transmission cable has been made. This study was carried out incorporating a fringe projection method for the experimental part and horizontal taut string model for theoretical one. However, this kind of model ignores some inherent properties such as cable sag and cable inclination. Then, this work reports advances on aeolic vibration considering real cables. Catenary and sag are considered in our theoretical model in such a way that an optical theodolite for measuring has been used. Preliminary measurements of the catenary as well as numerical simulation of a sagged cable vibration are given.
4. Grounding Effect on Common Mode Interference of Underground Inverter
CHENG Qiang
2013-09-01
Full Text Available For the neutral point not grounded characteristics of underground power supply system in coal mine, this paper studied common mode equivalent circuit of underground PWM inverter, and extracted parasitic parameters of interference propagation path. The author established a common mode and differential mode model of underground inverter. Taking into account the rise time of PWM, the simulation results of conducted interference by Matlab software is compared with measurement spectrum on the AC side and motor side of converter, the difference is consistent showing that the proposed method has some validity. After Comparison of calculation results by Matlab simulation ,it can be concluded that ungrounded neutral of transformer could redue common mode current in PWM system, but not very effective, the most efficient way is to increase grounding impedance of inverter and motor.
5. Offshore Cable Installation - Lillgrund. Lillgrund Pilot Project
Unosson, Oscar (Vattenfall Vindkraft AB, Stockholm (Sweden))
2009-01-15
This report describes the installation method and the experiences gained during the installation of the submarine cables for the offshore wind farm at Lillgrund. The wind farm consists of 48 wind turbines and is expected to produce 0.33 TWh annually. Different aspects of the installation, such as techniques, co-operation between the installation teams, weather conditions and regulatory and environmental issues are described in this report. In addition, recommendations and guidelines are provided, which hopefully can be utilised in future offshore wind projects. The trenches, in which the submarine cables were laid, were excavated weeks before the cable laying. This installation technique proved to be successful for the laying of the inter array cables. The export cable, however, was laid into position with difficulty. The main reason why the laying of the export cable proved more challenging was due to practical difficulties connected with the barge entrusted with the cable laying, Nautilus Maxi. The barge ran aground a number of times and it had difficulties with the thrusters, which made it impossible to manoeuvre. When laying the inter array cables, the method specification was closely followed, and the laying of the cables was executed successfully. The knowledge and experience gained from the offshore cable installation in Lillgrund is essential when writing technical specifications for new wind plant projects. It is recommended to avoid offshore cable installation work in winter seasons. That will lower the chances of dealing with bad weather and, in turn, will reduce the risks
6. Self-healing cable apparatus and methods
Huston, Dryver (Inventor); Esser, Brian (Inventor)
2007-01-01
Self-healing cable apparatus and methods are disclosed. The cable has a central core surrounded by an adaptive cover that can extend over the entire length of the cable or just one or more portions of the cable. The adaptive cover includes a protective layer having an initial damage resistance, and a reactive layer. When the cable is subjected to a localized damaging force, the reactive layer responds by creating a corresponding localized self-healed region. The self-healed region provides the cable with enhanced damage resistance as compared to the cable's initial damage resistance. Embodiments of the invention utilize conventional epoxies or foaming materials in the reactive layer that are released to form the self-healed region when the damaging force reaches the reactive layer.
7. Electrical testing of generator station cables
Tests have been performed at a decommissioned nuclear plant to assess the ability of electrical diagnostic tests to determine the remaining life of cable insulation. Power and control cables with either SBR or PVC insulation were tested. These materials are typical of cables in plants built before 1960. Insulation resistance, capacitance, dissipation factor and partial discharge activity were not correlated to the dc breakdown voltage of the cables, which is taken as a measure of insulation condition. Thus it is uncertain if such tests can be used to predict remaining life, especially if historical data has not been collected. All the cables had very high dc breakdown voltages, which was consistent with the generally good physical condition of the cables. Based on this limited study, it seems that hipot tests may be the only convenient electrical method currently available to assure the condition of cables in a generating station undergoing life extension. However more work is needed to determine suitable hipot test voltages
8. Corrosion monitoring of carbon steel in the bentonite in deep underground
In previous study, a corrosion sensor has been developed and its applicability to monitoring of the corrosion behavior of carbon steel overpack has been confirmed. In this study, a simulated overpack was placed with buffer material composed mainly of bentonite in test tunnel of 350 m deep underground constructed at Horonobe underground research laboratory. The corrosion monitoring was performed by AC impedance method using the corrosion sensors embeded in the buffer material. (author)
9. Ripple current loss measurement with DC bias condition for high temperature superconducting power cable using calorimetry method
Kim, D.W.; Kim, J.G.; Kim, A.R. [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Park, M., E-mail: [email protected] [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Yu, I.K. [Changwon National University, 9 sarim-dong, Changwon 641-773 (Korea, Republic of); Sim, K.D.; Kim, S.H.; Lee, S.J.; Cho, J.W. [Superconducting Device and Cryogenics Group, Korea Electrotechnology Research Institute, Changwon, 641-120 (Korea, Republic of); Won, Y.J. [Korea Electric Power Corporation, 411, youngdong-dearo, Gangnam-gu, Seoul (Korea, Republic of)
2010-11-01
The authors calculated the loss of the High Temperature Superconducting (HTS) model cable using Norris ellipse formula, and measured the loss of the model cable experimentally. Two kinds of measuring method are used. One is the electrical method, and the other is the calorimetric method. The electrical method can be used only in AC condition. But the calorimetric method can be used in both AC and DC bias conditions. In order to propose an effective measuring approach for Ripple Dependent Loss (RDL) under DC bias condition using the calorimetric method, Bismuth Strontium Calcium Copper Oxide (BSCCO) wires were used for the HTS model cable, and the SUS tapes were used as a heating tape to make the same pattern of the temperature profiles as in the electrical method without the transport current. The temperature-loss relations were obtained by the electrical method, and then applied to the calorimetric method by which the RDL under DC bias condition was well estimated.
10. Ripple current loss measurement with DC bias condition for high temperature superconducting power cable using calorimetry method
The authors calculated the loss of the High Temperature Superconducting (HTS) model cable using Norris ellipse formula, and measured the loss of the model cable experimentally. Two kinds of measuring method are used. One is the electrical method, and the other is the calorimetric method. The electrical method can be used only in AC condition. But the calorimetric method can be used in both AC and DC bias conditions. In order to propose an effective measuring approach for Ripple Dependent Loss (RDL) under DC bias condition using the calorimetric method, Bismuth Strontium Calcium Copper Oxide (BSCCO) wires were used for the HTS model cable, and the SUS tapes were used as a heating tape to make the same pattern of the temperature profiles as in the electrical method without the transport current. The temperature-loss relations were obtained by the electrical method, and then applied to the calorimetric method by which the RDL under DC bias condition was well estimated.
11. An Analytical Benchmark for the Calculation of Current Distribution in Superconducting Cables
Bottura, L; Fabbri, M G
2002-01-01
The validation of numerical codes for the calculation of current distribution and AC loss in superconducting cables versus experimental results is essential, but could be affected by approximations in the electromagnetic model or incertitude in the evaluation of the model parameters. A preliminary validation of the codes by means of a comparison with analytical results can therefore be very useful, in order to distinguish among different error sources. We provide here a benchmark analytical solution for current distribution that applies to the case of a cable described using a distributed parameters electrical circuit model. The analytical solution of current distribution is valid for cables made of a generic number of strands, subjected to well defined symmetry and uniformity conditions in the electrical parameters. The closed form solution for the general case is rather complex to implement, and in this paper we give the analytical solutions for different simplified situations. In particular we examine the ...
12. Study on the effects of cable sliding motion on the seismic response of cable tray
In various industrial plants such as thermal power plants, nuclear power plants or chemical plants, many cable trays are generally used for supporting cables by which control signals will be transmitted. Cable trays are generally made by thin steel plates both sides of which are folded in the vertical direction, while cables are simply placed on the tray. Thus, cables begin to slides when the response acceleration of trays exceeds some amount of value. Consequently, seismic responses of cable tray will also depend on the occurrence of sliding motion of cables. Therefore, cable trays are seen as highly nonlinear structural systems. In this study, seismic responses of the cable tray are investigated analytically considering the cable sliding motions. A cable tray is modeled by a two-degree-of-freedom system. Response acceleration and displacement of the tray and the cable are evaluated for seismic inputs. It is confirmed that the sliding motion of the cable has very large influences on the seismic responses of the cable tray. (author)
13. LUNA: Nuclear astrophysics underground
Underground nuclear astrophysics with LUNA at the Laboratori Nazionali del Gran Sasso spans a history of 20 years. By using the rock overburden of the Gran Sasso mountain chain as a natural cosmic-ray shield very low signal rates compared to an experiment on the surface can be tolerated. The cross sectons of important astrophysical reactions directly in the stellar energy range have been successfully measured. In this proceeding we give an overview over the key accomplishments of the experiment and an outlook on its future with the expected addition of an additional accelerator to the underground facilities, enabling the coverage of a wider energy range and the measurement of previously inaccessible reactions
14. Jiangmen Underground Neutrino Observatory
He, Miao
2014-01-01
The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose neutrino-oscillation experiment designed to determine the neutrino mass hierarchy and to precisely measure oscillation parameters by detecting reactor antineutrinos, observe supernova neutrinos, study the atmospheric, solar neutrinos and geo-neutrinos, and perform exotic searches, with a 20 kiloton liquid scintillator detector of unprecedented $3\\%$ energy resolution (at 1 MeV) at 700-meter deep underground and to have other rich scientific possibilities. Currently MC study shows a sensitivity of the mass hierarchy to be $\\overline{\\Delta\\chi^2}\\sim 11$ and $\\overline{\\Delta\\chi^2}\\sim 16$ in a relative and an absolute measurement, respectively. JUNO has been approved by Chinese Academy of Sciences in 2013, and an international collaboration was established in 2014. The civil construction is in preparation and the R$\\&$D of the detectors are ongoing. A new offline software framework was developed for the detector simulation, the event ...
15. Underground Economy in Croatia
Marija Švec
2009-01-01
The subject of this paper is to estimate the size of underground economy in the period 2001-2007 using labour approach. Two types of data are used: administrative and survey. The main questions are: How did the activity rates move? What is the relationship between activity rates and the size of shadow economy? Is there correlation between official employment, official unemployment and unofficial employment (shadow economy) and what is it like? What is the position of Croatia considering the m...
16. Nuclear plant undergrounding
Under Section 25524.3 of the Public Resources Code, the California Energy Resources Conservation and Development Commission (CERCDC) was directed to study ''the necessity for '' and the effectiveness and economic feasibility of undergrounding and berm containment of nuclear reactors. The author discusses the basis for the study, the Sargent and Lundy (S and L) involvement in the study, and the final conclusions reached by S and L
17. Monitoring underground movements
Antonella Del Rosso
2015-01-01
On 16 September 2015 at 22:54:33 (UTC), an 8.3-magnitude earthquake struck off the coast of Chile. 11,650 km away, at CERN, a new-generation instrument – the Precision Laser Inclinometer (PLI) – recorded the extreme event. The PLI is being tested by a JINR/CERN/ATLAS team to measure the movements of underground structures and detectors. The Precision Laser Inclinometer during assembly. The instrument has proven very accurate when taking measurements of the movements of underground structures at CERN. The Precision Laser Inclinometer is an extremely sensitive device capable of monitoring ground angular oscillations in a frequency range of 0.001-1 Hz with a precision of 10-10 rad/Hz1/2. The instrument is currently installed in one of the old ISR transfer tunnels (TT1) built in 1970. However, its final destination could be the ATLAS cavern, where it would measure and monitor the fine movements of the underground structures, which can affect the precise posi...
18. Experimental verification of the effect of cable length on voltage distribution in stator winding of an induction motor under surge condition
Oyegoke, B.S. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Electromechanics
1997-12-31
This paper presents the results of surge distribution tests performed on a stator of a 6 kV induction motor. The primary aim of these tests was to determine the wave propagation properties of the machine winding fed via cables of different lengths. Considering the measured resorts, conclusions are derived regarding the effect of cable length on the surge distribution within the stator winding of an ac motor. (orig.) 15 refs.
19. Performance evolution of 60 kA HTS cable prototypes in the EDIPO test facility
Bykovsky, N.; Uglietti, D.; Sedlak, K.; Stepanov, B.; Wesche, R.; Bruzzone, P.
2016-08-01
During the first test campaign of the 60 kA HTS cable prototypes in the EDIPO test facility, the feasibility of a novel HTS fusion cable concept proposed at the EPFL Swiss Plasma Center (SPC) was successfully demonstrated. While the measured DC performance of the prototypes at magnetic fields from 8 T to 12 T and for currents from 30 kA to 70 kA was close to the expected one, an initial electromagnetic cycling test (1000 cycles) revealed progressive degradation of the performance in both the SuperPower and SuperOx conductors. Aiming to understand the reasons for the degradation, additional cycling (1000 cycles) and warm up-cool down tests were performed during the second test campaign. I c performance degradation of the SuperOx conductor reached ∼20% after about 2000 cycles, which was reason to continue with a visual inspection of the conductor and further tests at 77 K. AC tests were carried out at 0 and 2 T background fields without transport current and at 10 T/50 kA operating conditions. Results obtained in DC and AC tests of the second test campaign are presented and compared with appropriate data published recently. Concluding the first iteration of the HTS cable development program at SPC, a summary and recommendations for the next activity within the HTS fusion cable project are also reported.
20. Stability of Nb-Ti Rutherford Cables Exhibiting Different Contact Resistances
Willering, G P; Kaugerts, J; ten Kate, H H J
2008-01-01
Dipole magnets for the so-called SIS-300 heavy-ion synchrotron at GSI are designed to generate 6Â T with a field sweep rate of 1Â T/s. It is foreseen to wind the magnets with a 36 strands Nb-Ti Rutherford cable. An important issue in the cable design is sufficiently low AC loss and stability as well. In order to keep the AC loss at low level, the contact resistance between crossing strands Rc is kept high by putting a stainless steel core in the cable. The contact resistance between adjacent strands Ra is controlled by oxidation of the Sn-Ag coating of the strands, like in the LHC. In order to investigate the effect of Ra on the stability of the cable, we prepared four samples with different Ra by varying the heat treatment and applying a soldering technique, resulting in values between 1Â mW to 9Â mW. The stability of each sample against transient point-like heat pulses was measured. The results of the stability experiments and a comparison with calculations using the network model CUDI are presented...
1. The Mathematical Modelling of Heat Transfer in Electrical Cables
Bugajev Andrej
2014-05-01
Full Text Available This paper describes a mathematical modelling approach for heat transfer calculations in underground high voltage and middle voltage electrical power cables. First of the all typical layout of the cable in the sand or soil is described. Then numerical algorithms are targeted to the two-dimensional mathematical models of transient heat transfer. Finite Volume Method is suggested for calculations. Different strategies of nonorthogonality error elimination are considered. Acute triangles meshes were applied in two-dimensional domain to eliminate this error. Adaptive mesh is also tried. For calculations OpenFOAM open source software which uses Finite Volume Method is applied. To generate acute triangles meshes aCute library is used. The efficiency of the proposed approach is analyzed. The results show that the second order of convergence or close to that is achieved (in terms of sizes of finite volumes. Also it is shown that standard strategy, used by OpenFOAM is less efficient than the proposed approach. Finally it is concluded that for solving real problem a spatial adaptive mesh is essential and adaptive time steps also may be needed.
2. Environment Of Underground Water And Pollution
Han, Jeong Sang
1998-02-15
This book deals with environment of underground water and pollution, which introduces the role of underground water in hydrology, definition of related study of under water, the history of hydro-geology, basic conception of underground water such as origin of water, and hydrogeologic characteristic of aquifers, movement of underground water, hydrography of underground water and aquifer test analysis, change of an underground water level, and water balance analysis and development of underground water.
3. Environment Of Underground Water And Pollution
This book deals with environment of underground water and pollution, which introduces the role of underground water in hydrology, definition of related study of under water, the history of hydro-geology, basic conception of underground water such as origin of water, and hydrogeologic characteristic of aquifers, movement of underground water, hydrography of underground water and aquifer test analysis, change of an underground water level, and water balance analysis and development of underground water.
4. Development of a 10 m long superconducting multistrand conductor for power transmission cables
A 10 m long HTS cable conductor was stranded with an industrial winding process from 2 km of Ag/Bi2223 tapes. It was installed in a vacuum cryostat and was force cooled by pressurized liquid nitrogen. DC- and AC-load tests were performed while varying the frequency and amplitude of the current. The critical current of the conductor is 5000 A. This model of a power transmission cable demonstrates very low AC losses of 0.8 W m-1 at 2000 Arms/50 Hz measured both with an electric transport and a calorimetric method. The AC losses vary linearly with frequency, P ∝ f, and have a current dependence slightly lower than P ∝ I3. The magnitude of the losses is clearly lower than predicted by the block model version of the Bean model. The model for uniform current distribution (UCD) improves the quantitative description of the losses. From these experiments we conclude that our low loss winding design of the conductor is an early stage of an economical HTS power transmission cable. (author)
5. Critical state solution of a cable made of curved thin superconducting tapes
In this paper, we develop a method based on the critical state for calculating the current and field distributions and AC losses in a cable made of curved thin superconducting tapes. The method also includes the possibility of considering spatial variation of the critical current density, which may be the result of the manufacturing process. For example, rare-earth-based coated conductors are known to have a decrease in transport properties near the edges of the tape: this influences the way the current and field penetrate the sample and, consequently, the AC losses. We demonstrate that curved tapes arranged on a cylindrical former behave as an infinite horizontal stack of straight tapes, and we compare the AC losses in a variety of working conditions, both without and with the lateral dependence of the critical current density. This model and subsequent similar approaches can be of interest for various applications of coated conductors, including power cables and conductor-on-round-core cables. (paper)
6. AC losses in circular arrangements of parallel superconducting tapes
Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten; Däumling, Manfred; Olsen, Søren Krüger; Tønnesen, Ole
The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two arrangem......The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two...... arrangements, scale with the number of tapes and hence appear to be independent of the diameter.However, the AC loss per tape (for a given current per tape) appears to decrease with increasing diameter of the circular arrangement. Compared to a model for the AC loss in a continuous superconducting layer...... (Monoblock model) the measured values are about half an order of magnitude higher than expected for the small diameter arrangement. When compared to the AC loss calculated for N individual superconducting tapes using a well known model ( Norris elliptical) the difference is slightly smaller....
7. AC losses in circular arrangements of parallel superconducting tapes
Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten; Däumling, Manfred;
1998-01-01
The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two arrangem......The DC and AC properties of superconducting tapes connected in parellel and arranged in a single closed layer on two tubes (correspondig to power cable models with infinite pitch) with different diameters are compared. We find that the DC properties, i.e. the critical currents of the two...... arrangements, scale with the number of tapes and hence appear to be independent of the diameter.However, the AC loss per tape (for a given current per tape) appears to decrease with increasing diameter of the circular arrangement. Compared to a model for the AC loss in a continuous superconducting layer...... (Monoblock model) the measured values are about half an order of magnitude higher than expected for the small diameter arrangement. When compared to the AC loss calculated for N individual superconducting tapes using a well known model ( Norris elliptical) the difference is slightly smaller....
8. Free and forced convective cooling of pipe-type electric cables. Volume 2: electrohycrodynamic pumping. Final report
Chato, J.C.; Crowley, J.M.
1981-05-01
A multi-faceted research program has been performed to investigate in detail several aspects of free and forced convective cooling of underground electric cable systems. There were two main areas of investigation. The first one, reported in Volume 1, dealt with the fluid dynamic and thermal aspects of various components of the cable system. In particular, friction factors for laminar flow in the cable pipes with various configurations were determined using a finite element technique; the temperature distributions and heat transfer in splices were examined using a combined analytical numerical technique; the pressure drop and heat transfer characteristics of cable pipes in the transitional and turbulent flow regime were determined experimentally in a model study; and full-scale model experimental work was carried out to determine the fluid dynamic and thermal characteristics of entrance and exit chambers for the cooling oil. The second major area of activity, reported in this volume, involved a feasibility study of an electrohydrodynamic pump concept utilizing a traveling electric field generated by a pumping cable. Experimental studies in two different configurations as well as theoretical calculations showed that an electrohydrodynamic pump for the moving of dielectric oil in a cable system is feasible.
9. Modeling and Filter Design for Overvoltage Mitigation in a Motor Drive System with a Long Cable
Matsumura, Itaru; Akagi, Hirofumi
This paper presents an intensive discussion on modeling an adjustable-speed motor drive system consisting of a voltage-source PWM inverter and an induction motor that are connected by a three-phase symmetric, long cable with a grounding wire lead. Then, it describes a design procedure for a parallel-connected R-L filter in each phase that can mitigate the overvoltage appearing at the motor terminals. The model developed in this paper focuses on the inherent “ringing frequency” of the cable, where the ringing frequency is inversely proportional to cable length. When no filter is used, the so-called “impedance mismatch” causes the reflection of a voltage-traveling wave at both the inverter and the motor terminals. As a result, the impedance mismatch generates an overvoltage that may reach twice the inverter dc-link voltage at the motor terminals. The overvoltage may damage the motor-winding insulation, and may cause it to breakdown. Although an R-L filter installed on the ac side of the inverter can reduce the overvoltage, it would be difficult to design the filter effectively for long cables of different lengths. The effectiveness and validity of the simple design procedure described in this paper are confirmed on a 400-V, 15-kW experimental system with either a 100-m or 200-m-long cable.
10. Field application of a cable NDT system for cable-stayed bridge using MFL sensors integrated
In this study, an automated cable non-destructive testing(NDT) system was developed to monitor the steel cables that are a core component of cable-stayed bridges. The magnetic flux leakage(MFL) method, which is suitable for ferromagnetic continuum structures and has been verified in previous studies, was applied to the cable inspection. A multi-channel MFL sensor head was fabricated using hall sensors and permanent magnets. A wheel-based cable climbing robot was fabricated to improve the accessibility to the cables, and operating software was developed to monitor the MFL-based NDT research and control the climbing robot. Remote data transmission and robot control were realized by applying wireless LAN communication. Finally, the developed element techniques were integrated into an MFL-based cable NDT system, and the field applicability of this system was verified through a field test at Seohae Bridge, which is a typical cable-stayed bridge currently in operation.
11. Cable force monitoring system of cable stayed bridges using accelerometers inside mobile smart phone
Zhao, Xuefeng; Yu, Yan; Hu, Weitong; Jiao, Dong; Han, Ruicong; Mao, Xingquan; Li, Mingchu; Ou, Jinping
2015-03-01
Cable force is one of the most important parameters in structural health monitoring system integrated on cable stayed bridges for safety evaluation. In this paper, one kind of cable force monitoring system scheme was proposed. Accelerometers inside mobile smart phones were utilized for the acceleration monitoring of cable vibration. Firstly, comparative tests were conducted in the lab. The test results showed that the accelerometers inside smartphones can detect the cable vibration, and then the cable force can be obtained. Furthermore, there is good agreement between the monitoring results of different kinds of accelerometers. Finally, the proposed cable force monitoring system was applied on one cable strayed bridge structure, the monitoring result verified the feasibility of the monitoring system.
12. Occupational Asthma in a Cable Manufacturing Company
Attarchi, Mirsaeed; Dehghan, Faezeh; Yazdanparast, Taraneh; Mohammadi, Saber; Golchin, Mahdie; Sadeghi, Zargham; Moafi, Masoud; Seyed Mehdi, Seyed Mohammad
2014-01-01
Background: During the past decade, incidence of asthma has increased, which might have been due to environmental exposures. Objectives: Considering the expansion of cable manufacturing industry in Iran, the present study was conducted to evaluate the prevalence of occupational asthma in a cable manufacturing company in Iran as well as its related factors. Patients and Methods: This study was conducted on employees of a cable manufacturing company in Yazd, Iran, in 2012. The workers were divi...
13. Review of high voltage direct current cables
Chen, George; Miao, Hao; Z. Xu; A. S. Vaughan; Cao, Junzheng; Wang, Haitian
2015-01-01
Increased renewable energy integration and international power trades have led to the construction and development of new HVDC transmission systems. HVDC cables, in particular, play an important role in undersea power transmission and offshore renewable energy integration having lower losses and higher reliability. In this paper, the current commercial feasibility of HVDC cables and the development of different types of HVDC cables and accessories are reviewed. The non-uniform electric field ...
14. Optimal Sensor Placement for Stay Cable Damage Identification of Cable-Stayed Bridge under Uncertainty
Li-Qun Hou; Xue-Feng Zhao; Rui-Cong Han; Chun-Cheng Liu
2013-01-01
Large cable-stayed bridges utilize hundreds of stay cables. Thus, placing a sensor on every stay cable of bridges for stay cable damage identification (SCDI) is costly and, in most cases, not necessary. Optimal sensor placement is a significant and critical issue for SCDI. This paper proposes the criteria for sensor quantity and location optimization for SCDI on the basis of the concept of damage identification reliability index (DIRI) under uncertainty. Random elimination (RE) algorithm and ...
15. The underground economy in Romania
Eugenia Ramona MARA
2011-01-01
The actual economic crisis has a major impact on the underground economy because of tax burden increase especially. This study realizes an analysis of the major implications of the economic crises on the size and the consequences of the underground activities. Also we try to reveal the correlation between the underground economy and the official one. The conclusion of this study is that the shadow activities have grown since the financial crisis began.
16. Underground economy and aggregate fluctuations
Juan Carlos Conesa Roca; Carlos Díaz Moreno; José Enrique Galdón Sánchez
2001-01-01
This paper explores the role of underground economic activities as an explanation of differences in registered aggregate fluctuations. In order to do so, we introduce an underground economy sector in an otherwise standard Real Business Cycle model and calibrate it to the USA economy. We find that, at low frequencies, Europe fluctuates more than the USA, while its participation rate is smaller. The existence of underground activities rationalizes the negative relationship between participation...
17. How do you like them cables?
Sergei Malyukov
Cabling work is not for clautrophobic people! Cables are like the blood vessels and nervous system of ATLAS. With the help of all these cables, we can power ATLAS, control the detector and read out the data. Like the human blood vessels, they penetrate inside the ATLAS volume, reaching each of its elements. The ATLAS developers started to think about design of services, cables and pipes at the very first stages of the project. The cabling project has been developing most intensively during the last five years, passing through the projection and CAD design phases, then the installation of cable trays and finally the cables. The cable installation itself took two and a half years and was done by teams of technicians from several institutes from Russia, the Czech Republic and Poland. Here are some numbers to illustrate the scale of the ATLAS cabling system. More than 25000 optical fiber channels are used for reading the information from the sub-detectors and delivering the timing signals. The total numbe...
18. Underground nuclear waste containments
In the United States, about a hundred million gallons of high-level nuclear waste are stored in underground containments. Basically, these containments are of two different designs: single-shell and double-shell structures. The single-shell structures consist of reinforced concrete cylindrical walls seated on circular mats and enclosed on top with torispherical domes or circular flat roofs. The walls and the basemats are lined with carbon steel. The double-shell structures provide another layer of protection and constitute a completely enclosed steel containment within the single-shell structure leaving an annular space between the two walls. Single-shell containments are of earlier vintage and were built in the period 1945-1965. Double-shell structures were built through the 1960s and 1970s. Experience gained in building and operating the single-shell containments was used in enhancing the design and construction of the double-shell structures. Currently, there are about 250 underground single-shell and double-shell structures containing the high-level waste with an inventory of about 800 million curies. During their service lives, especially in early stages, these structures were subjected to thermal excursions of varying extents; also, they have aged in the chemical environment. Furthermore, in their remaining service lives, the structures may be subjected to loads for which they were not designed, such as larger earthquakes or chemical explosions. As a result, the demonstration of safety of these underground nuclear containments poses a challenge to structural engineers, which increases with time. Regardless of current plans for gradual retrieval of the waste and subsequent solidification for disposal, many of these structures are expected to continue to contain the waste through the next 20-40 years. In order to verify their structural capabilities in fulfilling this mission, several studies were recently performed at Brookhaven National Laboratory
19. Underground space planning in Helsinki
Ilkka Vähäaho
2014-01-01
This paper gives insight into the use of underground space in Helsinki, Finland. The city has an underground master plan (UMP) for its whole municipal area, not only for certain parts of the city. Further, the decision-making history of the UMP is described step-by-step. Some examples of underground space use in other cities are also given. The focus of this paper is on the sustainability issues related to urban underground space use, including its contribution to an environmentally sustainab...
20. Regulated underground storage tanks
This guidance package is designed to assist DOE Field operations by providing thorough guidance on the underground storage tank (UST) regulations. [40 CFR 280]. The guidance uses tables, flowcharts, and checklists to provide a ''roadmap'' for DOE staff who are responsible for supervising UST operations. This package is tailored to address the issues facing DOE facilities. DOE staff should use this guidance as: An overview of the regulations for UST installation and operation; a comprehensive step-by-step guidance for the process of owning and operating an UST, from installation to closure; and a quick, ready-reference guide for any specific topic concerning UST ownership or operation
1. Dossier: underground storage
This dossier reviews the main concepts of storage in geologic formations: shape of artificial cavities; natural reservoirs: natural gas storage in aquifers, heat storage, karsts and caves; artificial reservoirs: salt dissolution cavities, salt mines, enlargement of cavities, storage of metal wastes; reservoirs in mining cavities: hydrocarbons storage (tightness, steel coated cavities), cryogenic storage; use of ancient infrastructures (mines, quarries, galleries): hydrocarbons storage, toxic wastes storage, radioactive wastes disposal, reversible radioactive wastes storage, solar neutrons trapping in underground galleries, storage of film archives etc.. (J.S.)
2. Underground engineering applications
Developments of any underground engineering application utilizing nuclear explosives involve answering the same questions one encounters in any new area of technology: What are the characteristics of the new tool? How is it applicable to the job to be done? Is it safe to use? and, most importantly, is its use economically acceptable? The many facets of the answers to these questions will be explored. The general types of application presently under consideration will also be reviewed, with particular emphasis on those specific projects actively being worked on by commercial interests and by the U.S. Atomic Energy Commission. (author)
3. Sanford Underground Research Facility - The United State's Deep Underground Research Facility
Vardiman, D.
2012-12-01
The 2.5 km deep Sanford Underground Research Facility (SURF) is managed by the South Dakota Science and Technology Authority (SDSTA) at the former Homestake Mine site in Lead, South Dakota. The US Department of Energy currently supports the development of the facility using a phased approach for underground deployment of experiments as they obtain an advanced design stage. The geology of the Sanford Laboratory site has been studied during the 125 years of operations at the Homestake Mine and more recently as part of the preliminary geotechnical site investigations for the NSF's Deep Underground Science and Engineering Laboratory project. The overall geology at DUSEL is a well-defined stratigraphic sequence of schist and phyllites. The three major Proterozoic units encountered in the underground consist of interbedded schist, metasediments, and amphibolite schist which are crosscut by Tertiary rhyolite dikes. Preliminary geotechnical site investigations included drift mapping, borehole drilling, borehole televiewing, in-situ stress analysis, laboratory analysis of core, mapping and laser scanning of new excavations, modeling and analysis of all geotechnical information. The investigation was focused upon the determination if the proposed site rock mass could support the world's largest (66 meter diameter) deep underground excavation. While the DUSEL project has subsequently been significantly modified, these data are still available to provide a baseline of the ground conditions which may be judiciously extrapolated throughout the entire Proterozoic rock assemblage for future excavations. Recommendations for facility instrumentation and monitoring were included in the preliminary design of the DUSEL project design and include; single and multiple point extensometers, tape extensometers and convergence measurements (pins), load cells and pressure cells, smart cables, inclinometers/Tiltmeters, Piezometers, thermistors, seismographs and accelerometers, scanners (laser
4. 30 CFR 75.343 - Underground shops.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground shops. 75.343 Section 75.343... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.343 Underground shops. (a) Underground...-3 through § 75.1107-16, or be enclosed in a noncombustible structure or area. (b) Underground...
5. Multinational underground nuclear parks
Newcomer countries expected to develop new nuclear power programs by 2030 are being encouraged by the International Atomic Energy Agency to explore the use of shared facilities for spent fuel storage and geologic disposal. Multinational underground nuclear parks (M-UNPs) are an option for sharing such facilities. Newcomer countries with suitable bedrock conditions could volunteer to host M-UNPs. M-UNPs would include back-end fuel cycle facilities, in open or closed fuel cycle configurations, with sufficient capacity to enable M-UNP host countries to provide for-fee waste management services to partner countries, and to manage waste from the M-UNP power reactors. M-UNP potential advantages include: the option for decades of spent fuel storage; fuel-cycle policy flexibility; increased proliferation resistance; high margin of physical security against attack; and high margin of containment capability in the event of beyond-design-basis accidents, thereby reducing the risk of Fukushima-like radiological contamination of surface lands. A hypothetical M-UNP in crystalline rock with facilities for small modular reactors, spent fuel storage, reprocessing, and geologic disposal is described using a room-and-pillar reference-design cavern. Underground construction cost is judged tractable through use of modern excavation technology and careful site selection. (authors)
6. RP delves underground
Anaïs Schaeffer
2011-01-01
The LHC’s winter technical stop is rapidly approaching. As in past years, technical staff in their thousands will be flocking to the underground areas of the LHC and the Linac2, Booster, PS and SPS injectors. To make sure they are protected from ionising radiation, members of the Radiation Protection Group will perform an assessment of the levels of radioactivity in the tunnels as soon as the beams have stopped. Members of the Radiation Protection Group with their precision instruments that measure radioactivity. At 7-00 a.m. on 8 December the LHC and all of the upstream accelerators will begin their technical stop. At 7-30 a.m., members of the Radiation Protection Group will enter the tunnel to perform a radiation mapping, necessary so that the numerous teams can do their work in complete safety. “Before we proceed underground, we always check first to make sure that the readings from the induced radioactivity monitors installed in the tunnels are all normal,&rdqu...
7. Going Underground in Singapore
John Osborne (GS/SEM)
2010-01-01
Singapore has plans to build a massive Underground Science City (USC) housing R&D laboratories and IT data centres. A delegation involved in the planning to build the subterranean complex visited CERN on 18 October 2010 to learn from civil engineers and safety experts about how CERN plans and constructs its underground facilities. The delegation from Singapore. The various bodies and corporations working on the USC project are currently studying the feasibility of constructing up to 40 caverns (60 m below ground) similar in size to an LHC experiment hall, in a similar type of rock. Civil engineering and geotechnical experts are calculating the maximum size of the cavern complex that can be safely built. The complex could one day accommodate between 3000 and 5000 workers on a daily basis, so typical issues of size and number of access shafts need to be carefully studied. At first glance, you might not think the LHC has much in common with the USC project; as Rolf Heuer pointed out: &ldq...
8. Multinational underground nuclear parks
Myers, C.W. [Nuclear Engineering and Nonproliferation Division, Los Alamos National Laboratory, MS F650, Los Alamos, NM 87544 (United States); Giraud, K.M. [Wolf Creek Nuclear Operating Corporation, 1550 Oxen Lane NE, P.O. Box 411, Burlington, KS 66839-0411 (United States)
2013-07-01
Newcomer countries expected to develop new nuclear power programs by 2030 are being encouraged by the International Atomic Energy Agency to explore the use of shared facilities for spent fuel storage and geologic disposal. Multinational underground nuclear parks (M-UNPs) are an option for sharing such facilities. Newcomer countries with suitable bedrock conditions could volunteer to host M-UNPs. M-UNPs would include back-end fuel cycle facilities, in open or closed fuel cycle configurations, with sufficient capacity to enable M-UNP host countries to provide for-fee waste management services to partner countries, and to manage waste from the M-UNP power reactors. M-UNP potential advantages include: the option for decades of spent fuel storage; fuel-cycle policy flexibility; increased proliferation resistance; high margin of physical security against attack; and high margin of containment capability in the event of beyond-design-basis accidents, thereby reducing the risk of Fukushima-like radiological contamination of surface lands. A hypothetical M-UNP in crystalline rock with facilities for small modular reactors, spent fuel storage, reprocessing, and geologic disposal is described using a room-and-pillar reference-design cavern. Underground construction cost is judged tractable through use of modern excavation technology and careful site selection. (authors)
9. Understanding Electrical Treeing Phenomena in XLPE Cable Insulation Adopting UHF Technique
Sarathi, Ramanujam; Nandini, Arya; Danikas, Michael G.
2011-03-01
A major cause for failure of underground cables is due to formation of electrical trees in the cable insulation. A variety of tree structure can form from a defect site in cable insulation viz bush-type trees, tree-like trees, fibrillar type trees, intrinsic type, depending on the applied voltage. Weibull studies indicate that a higher applied voltage enhances the rate of tree propagation thereby reducing the life of cable insulation. Measurements of injected current during tree propagation indicates that the rise time and fall time of the signal is of few nano seconds. In the present study, an attempt has been made to identify the partial discharges caused due to inception and propagation of electrical trees adopting UHF technique. It is realized that UHF signal generated during tree growth have signal bandwidth in the range of 0.5-2.0 GHz. The formation of streamer type discharge and Townsend type discharges during tree inception and propagation alters the shape of the tree formed. The UHF signal generated due to partial discharges formed during tree growth were analyzed adopting Ternary plot, which can allow one to classify the shape of tree structure formed.
10. Modern geodesy approach in underground mining
Mijalkovski, Stojance; Despodov, Zoran; Gorgievski, Cvetan; Bogdanovski, Goran; Mirakovski, Dejan; Hadzi-Nikolova, Marija; Doneva, Nikolinka
2013-01-01
This paper presents overview of the development of modern geodesy approach in underground mining. Correct surveying measurements have great importance in mining, especially underground mining as well as a major impact on safety in the development of underground mining facilities.
11. New Projects in Underground Physics
Goodman, Maury
2003-01-01
A large fraction of neutrino research is taking place in facilities underground. In this paper, I review the underground facilities for neutrino research. I discuss ideas for future reactor experiments being considered to measure theta_13 and the UNO proton decay project.
12. HAWAII LEAKING UNDERGROUND STORAGE TANKS
Point coverage of leaking underground storage tanks(LUST) for the state of Hawaii. The original database was developed and is maintained by the State of Hawaii, Dept. of Health. The point locations represent facilities where one or more leaking underground storage tank exists. ...
13. Radar polarimetry applied to the classification of underground targets
Moriyama, Toshifumi; Nakamura, Masafumi; Yamaguchi, Yoshio; Yamada, Hiroyoshi; Boerner, Wolfgang-Martin
1997-12-01
This paper discusses the classification of target buried in the underground by the radar polarimetry. The subsurface radar is used in the detection of objects buried beneath the ground surface, such as archeological exploration, pipes, gas cables and cavities. However, in addition to target echo, the subsurface radar receives various echoes including clutter, because the underground is inhomogeneous medium. Therefore, the subsurface radar needs the ability to distinguish these echoes. In order to enhance the ability, we first applied the polarization anisotropy coefficient to classify the echo into isotropic target (plate, sphere) and anisotropic target (wire, pipe). It is easy to find the man- made target buried in the underground by polarization anisotropy coefficient. Second, we used a three-component decomposition technique for a scattering matrix. Third, we tried to classify targets using polarimetric signature approach. Moreover, the characteristic polarization state gives the oriented angle of anisotropic target. Therefore, these values contribute the classification of the target. The field experiments using an FM-CW radar system were carried out to show the usefulness of the radar polarimetry. In this paper, several detection and classification results are displayed. It is shown that these techniques improve the detection capability of buried target.
14. Local Government Uses of Cable Television.
Cable Television Information Center, Washington, DC.
The local government cable access channel is essentially a television station completely controlled by the local government. It differs from a local broadcast television station by being able to reach only those places which are connected to the cable system, having much less programming distribution costs, and having the capacity to deliver…
15. Assessment of sodium conductor distribution cable
None
1979-06-01
The study assesses the barriers and incentives for using sodium conductor distribution cable. The assessment considers environmental, safety, energy conservation, electrical performance and economic factors. Along with all of these factors considered in the assessment, the sodium distribution cable system is compared to the present day alternative - an aluminum conductor system. (TFD)
16. 21 CFR 890.1175 - Electrode cable.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electrode cable. 890.1175 Section 890.1175 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1175 Electrode cable....
17. 14 CFR 25.689 - Cable systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Cable systems. 25.689 Section 25.689... STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Control Systems § 25.689 Cable systems. (a... smaller than 1/8 inch in diameter may be used in the aileron, elevator, or rudder systems; and (2)...
18. Cable Television: Its Urban Context and Programming.
Warthman, Forrest
Cable television's future in urban settings is discussed in the context of alternative media capable of serving similar markets with similar programing. In addition to cable television, other transmission networks such as the telephone network, radio and television broadcasting, microwave networks, domestic satellites, and recording media are…
19. Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method
A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method
20. Optical cable fault locating using Brillouin optical time domain reflectometer and cable localized heating method
Lu, Y. G.; Zhang, X. P.; Dong, Y. M.; Wang, F.; Liu, Y. H.
2007-07-01
A novel optical cable fault location method, which is based on Brillouin optical time domain reflectometer (BOTDR) and cable localized heating, is proposed and demonstrated. In the method, a BOTDR apparatus is used to measure the optical loss and strain distribution along the fiber in an optical cable, and a heating device is used to heat the cable at its certain local site. Actual experimental results make it clear that the proposed method works effectively without complicated calculation. By means of the new method, we have successfully located the optical cable fault in the 60 km optical fiber composite power cable from Shanghai to Shengshi, Zhejiang. A fault location accuracy of 1 meter was achieved. The fault location uncertainty of the new optical cable fault location method is at least one order of magnitude smaller than that of the traditional OTDR method.
1. Behaviour of electrical cables under fire conditions
A Fire Probabilistic Safety Assessment - called the Fire PSA - is being carried out by the French Institute of Radiological Protection and Nuclear Safety (IPSN) to be used in the framework of the safety assessment of operating 900 MWe PWRs. The aim of this study is to evaluate the core damage conditional probability which could result from a fire. A fire can induce unavailability of safety equipment, notably damaging electrical cables introducing a significant risk contributor. The purpose of this paper is to present the electrical cable fire tests carried out by IPSN to identify the failure modes and to determine the cable damage criteria. The impact of each kind of cable failure mode and the methodology used to estimate the conditional probability of a failure mode when cable damage occurred is also discussed. (orig.)
2. Underground space planning in Helsinki
Ilkka Vähäaho
2014-10-01
Full Text Available This paper gives insight into the use of underground space in Helsinki, Finland. The city has an underground master plan (UMP for its whole municipal area, not only for certain parts of the city. Further, the decision-making history of the UMP is described step-by-step. Some examples of underground space use in other cities are also given. The focus of this paper is on the sustainability issues related to urban underground space use, including its contribution to an environmentally sustainable and aesthetically acceptable landscape, anticipated structural longevity and maintaining the opportunity for urban development by future generations. Underground planning enhances overall safety and economy efficiency. The need for underground space use in city areas has grown rapidly since the 21st century; at the same time, the necessity to control construction work has also increased. The UMP of Helsinki reserves designated space for public and private utilities in various underground areas of bedrock over the long term. The plan also provides the framework for managing and controlling the city's underground construction work and allows suitable locations to be allocated for underground facilities. Tampere, the third most populated city in Finland and the biggest inland city in the Nordic countries, is also a good example of a city that is taking steps to utilise underground resources. Oulu, the capital city of northern Finland, has also started to ‘go underground’. An example of the possibility to combine two cities by an 80-km subsea tunnel is also discussed. A new fixed link would generate huge potential for the capital areas of Finland and Estonia to become a real Helsinki-Tallinn twin city.
3. Underground space planning in Helsinki
Ilkka Vhaho
2014-01-01
This paper gives insight into the use of underground space in Helsinki, Finland. The city has an under-ground master plan (UMP) for its whole municipal area, not only for certain parts of the city. Further, the decision-making history of the UMP is described step-by-step. Some examples of underground space use in other cities are also given. The focus of this paper is on the sustainability issues related to urban underground space use, including its contribution to an environmentally sustainable and aesthetically acceptable landscape, anticipated structural longevity and maintaining the opportunity for urban development by future generations. Underground planning enhances overall safety and economy effi-ciency. The need for underground space use in city areas has grown rapidly since the 21st century;at the same time, the necessity to control construction work has also increased. The UMP of Helsinki reserves designated space for public and private utilities in various underground areas of bedrock over the long term. The plan also provides the framework for managing and controlling the city’s underground con-struction work and allows suitable locations to be allocated for underground facilities. Tampere, the third most populated city in Finland and the biggest inland city in the Nordic countries, is also a good example of a city that is taking steps to utilise underground resources. Oulu, the capital city of northern Finland, has also started to‘go underground’. An example of the possibility to combine two cities by an 80-km subsea tunnel is also discussed. A new fixed link would generate huge potential for the capital areas of Finland and Estonia to become a real Helsinki-Tallinn twin city.
4. Underground layout tradeoff study
This report presents the results of a technical and economic comparative study of four alternative underground layouts for a nuclear waste geologic repository in salt. The four alternatives considered in this study are (1) separate areas for spent fuel (SF) and commercial high-level waste (CHLW); (2) panel alternation, in which SF and CHLW are emplaced in adjacent panels of rooms; (3) room alternation, in which SF and CHLW are emplaced in adjacent rooms within each panel; and (4) intimate mixture, in which SF and CHLW are emplaced in random order within each storage room. The study concludes that (1) cost is not an important factor; (2) the separate-areas and intimate-mixture alternatives appear, technically, to be more desirable than the other alternatives; and (3) the selection between the separate-areas and intimate mixture alternatives depends upon future resolution of site-specific and reprocessing questions. 5 refs., 6 figs., 12 tabs
5. Biofuel goes underground
Tollinsky, Norm
2011-09-15
Kirkland Lake Gold, a gold producer, is switching to a blend of biofuel to power the mine's underground equipment. Kirkland Lake Gold is using a soy-based product which has several advantages: less expensive: for example, the soybean-based biofuel used by Kirkland Lake Gold is 10 cents a liter less expensive than diesel; cleaner: biofuel can reduce emissions by up to 80 per cent compared to conventional diesel; and safer: biofuel is safer than miner's diesel because it has a much higher flash point. Testing with soybean-based biofuel began in the early 90s but its price was too high at that time. The federal government's regulation of renewable fuel quotas has led to the better availability of biofuel now. The supply should be doubled to meet government quotas.
6. ACAC Converters for UPS
Rusalin Lucian R. Păun
2008-05-01
Full Text Available This paper propose a new control technique forsingle – phase ACAC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.
7. Construction behavior of the first underground opening of the superconducting super collider project
Most underground structures of the Superconducting Super Collider (SSC) will be within the competent Austin Chalk (AC), an ideal tunneling medium; however, some structures will be within the very low strength Eagle Ford Shale (EFS). A 3 m diameter Exploratory Shaft, 82 m deep with a test adit at the AC/EFS contact was constructed as the first underground opening on the SSC to provide information on design parameters and construction behavior. The Exploratory Shaft was instrumented with piezometers, MPBXs, convergence anchors, inclinometer and heave gage casings, and an instrumented steel ring liner section. The shaft was deep enough to induce over-stress in the EFS. The geomechanical properties of the EFS and overlying AC, the instrumentation, and the insights gained for the SSC project are presented in this paper
8. Magnetic flux leakage-based steel cable NDE and damage visualization on a cable climbing robot
Kim, Ju-Won; Lee, Changgil; Park, Seunghee; Lee, Jong Jae
2012-04-01
The steel cables in long span bridges such as cable-stayed bridges and suspension bridges are critical members which suspend the load of main girders and bridge floor slabs. Damage of cable members can occur in the form of crosssectional loss caused by fatigue, wear, and fracture, which can lead to structural failure due to concentrated stress in the cable. Therefore, nondestructive examination of steel cables is necessary so that the cross-sectional loss can be detected. Thus, an automated cable monitoring system using a suitable NDE technique and a cable climbing robot is proposed. In this study, an MFL (Magnetic Flux Leakage- based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults (LF) of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the level of damage. Measured signals from the damaged specimen were compared with thresholds set for objective decision making. In addition, the measured magnetic flux signal was visualized into a 3D MFL map for convenient cable monitoring. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.
9. Non-cable vehicle guidance
Daugela, G.C.; Willott, A.M.; Chopiuk, R.G.; Thornton, S.E.
1988-06-01
The purpose is to determine the most promising driverless mine vehicle guidance systems that are not dependent on buried cables, and to plan their development. The project is presented in two phases: a preliminary study and literature review to determine whether suitable technologies exist to justify further work; and an in-depth assessment and selection of technologies for vehicle guidance. A large number of guidance elements are involved in a completely automated vehicle. The technologies that hold the best potential for development of guidance systems for mine vehicles are ultrasonics, radar, lasers, dead reckoning, and guidance algorithms. The best approach to adaptation of these technologies is on a step by step basis. Guidance modules that are complete in themselves and are designed to be integrated with other modules can provide short term benefits. Two modules are selected for development: the dragline operations monitor and automated machine control for optimized mining (AMCOM). 99 refs., 20 figs., 40 tabs.
10. Self-healing cable for extreme environments
Huston, Dryver R. (Inventor); Tolmie, Bernard R. (Inventor)
2009-01-01
Self-healing cable apparatus and methods disclosed. The self-healing cable has a central core surrounded by an adaptive cover that can extend over the entire length of the self-healing cable or just one or more portions of the self-healing cable. The adaptive cover includes an axially and/or radially compressible-expandable (C/E) foam layer that maintains its properties over a wide range of environmental conditions. A tape layer surrounds the C/E layer and is applied so that it surrounds and axially and/or radially compresses the C/E layer. When the self-healing cable is subjected to a damaging force that causes a breach in the outer jacket and the tape layer, the corresponding localized axially and/or radially compressed portion of the C/E foam layer expands into the breach to form a corresponding localized self-healed region. The self-healing cable is manufacturable with present-day commercial self-healing cable manufacturing tools.
11. Power plant practices to ensure cable operability
This report describes the design, installation, qualification, maintenance, and testing of nuclear power plant cables with regard to continued operability. The report was initiated after questions arose concerning inadvertent abuse of cables during installation at two nuclear power plants. The extent of the damage was not clear and there was a concern as to whether cables, if damaged, would be able to function under accident conditions. This report reviews and discusses installation practices in the industry. The report also discusses currently available troubleshooting and in-situ testing techniques and provides cautions for some cases which may lead to further cable damage. Improved troubleshooting techniques currently under development are also discussed. These techniques may reduce the difficulty of testing while being able to identify cable flaws more definitively. The report finds, in general, that nuclear power plant cables have been relatively trouble-free; however, there is a need for further research and development of troubleshooting techniques which will make cable condition testing easier and more reliable. Also, recommendations for ''good'' installation practices are needed
12. The effect of DC superimposed AC Voltage on Partial Discharges in Dielectric Bounded Cavities
Olsen, Pål Keim; Mauseth, Frank; Ildstad, Erling
2014-01-01
Voltage source converters is used in HVDC stations in offshore HVDC transmission systems, between the AC and DC power grid. The AC ripple voltage on the DC side of the HVDC stations can be in the range of 1-10 % of the nominal DC voltage, depending on the size of the filter employed. For offshore HVDC grids, there is a drive to use polymeric insulated cables on the DC side. This work investigates how an AC voltage at power frequency superimposed on DC voltage influence the partial discharge m...
13. 47 CFR 32.2424 - Submarine & deep sea cable.
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Submarine & deep sea cable. 32.2424 Section 32... Submarine & deep sea cable. (a) This account shall include the original cost of submarine cable and deep sea... defined below, are to be maintained for nonmetallic submarine and deep sea cable and metallic...
14. Basic cable routing guidelines for a fast reactor plant
In this paper the guidelines evolved for cable routing in 500 MWe Prototype Fast Breeder Reactor (PFBR) are presented. Safety related redundant system cables in a nuclear plant shall not become unavailable due to cable fire. This is ensured by proper cable routing in the plant in addition to the other general fire protection measures
15. Cable Television 1980: Status and Prospect for Higher Education.
Baus, F., Ed.
Baseline information for the would-be cable television educational programer is provided by two papers, one an overview of the state of the cable television industry, and the other a report on a marketing study conducted to determine consumer attitudes toward cable TV as an educational medium. In "The Promise and Reality of Cable Television,"…
16. The creation of high-temperature superconducting cables of megawatt range in Russia
Sytnikov, V. E.; Bemert, S. E.; Krivetsky, I. V.; Romashov, M. A.; Popov, D. A.; Fedotov, E. V.; Komandenko, O. V.
2015-12-01
Urgent problems of the power industry in the 21st century require the creation of smart energy systems, providing a high effectiveness of generation, transmission, and consumption of electric power. Simultaneously, the requirements for controllability of power systems and ecological and resource-saving characteristics at all stages of production and distribution of electric power are increased. One of the decision methods of many problems of the power industry is the development of new high-efficiency electrical equipment for smart power systems based on superconducting technologies to ensure a qualitatively new level of functioning of the electric power industry. The intensive research and development of new types of electrical devices based on superconductors are being carried out in many industrialized advanced countries. Interest in such developments has especially increased in recent years owing to the discovery of so-called high-temperature superconductors (HTS) that do not require complicated and expensive cooling devices. Such devices can operate at cooling by inexpensive and easily accessible liquid nitrogen. Taking into account the obvious advantages of superconducting cable lines for the transmission of large power flows through an electrical network, as compared with conventional cables, the Federal Grid Company of Unified Energy System (JSC FGC UES) initiated a research and development program including the creation of superconducting HTS AC and DC cable lines. Two cable lines for the transmitted power of 50 MVA/MW at 20 kV were manufactured and tested within the framework of the program.
17. Low coupling loss core-strengthened Bi 2212\\/Ag Rutherford cables
Collings, E W; Scanlan, R M; Dietderich, D R; Motowidlo, L R
1999-01-01
In a comprehensive "vertically integrated" program multifilamentary (MF) high temperature superconducting (HTSC) Bi:2212/Ag strand was fabricated using the powder-in-tube process and heat treated in oxygen by a modified standard $9 procedure. The reaction-heat-treatment (HT) was adjusted to maximize critical current (density), I/sub c/ (J /sub c/), as measured in various magnetic fields, B. A series of Rutherford cables was designed, each of which included a $9 metallic (Nichrome-80) core for strengthening and reduction of coupling loss. Prior to cable winding a series of tests examined the possibility of strand "poisoning" by the core during HT. Small model Rutherford cables were wound, $9 and after HT were prepared for I/sub c/(B) measurement and calorimetric measurement of AC loss and hence interstrand contact resistance I/sub c/(B). It was deduced that, if in direct contact with the strand during HT, the core $9 material can degrade the I/sub c/ of the cable; but steps can be taken to eliminate this probl...
18. The creation of high-temperature superconducting cables of megawatt range in Russia
Sytnikov, V. E., E-mail: [email protected]; Bemert, S. E.; Krivetsky, I. V.; Romashov, M. A. [JSC NTTs FSC EES (Russian Federation); Popov, D. A.; Fedotov, E. V.; Komandenko, O. V. [JSC Irkutskkabel (Russian Federation)
2015-12-15
Urgent problems of the power industry in the 21st century require the creation of smart energy systems, providing a high effectiveness of generation, transmission, and consumption of electric power. Simultaneously, the requirements for controllability of power systems and ecological and resource-saving characteristics at all stages of production and distribution of electric power are increased. One of the decision methods of many problems of the power industry is the development of new high-efficiency electrical equipment for smart power systems based on superconducting technologies to ensure a qualitatively new level of functioning of the electric power industry. The intensive research and development of new types of electrical devices based on superconductors are being carried out in many industrialized advanced countries. Interest in such developments has especially increased in recent years owing to the discovery of so-called high-temperature superconductors (HTS) that do not require complicated and expensive cooling devices. Such devices can operate at cooling by inexpensive and easily accessible liquid nitrogen. Taking into account the obvious advantages of superconducting cable lines for the transmission of large power flows through an electrical network, as compared with conventional cables, the Federal Grid Company of Unified Energy System (JSC FGC UES) initiated a research and development program including the creation of superconducting HTS AC and DC cable lines. Two cable lines for the transmitted power of 50 MVA/MW at 20 kV were manufactured and tested within the framework of the program.
19. A unique cabling machine designed to produce rutherford-type superconducting cable for the SSC project
Up to 25,000 Km of keystoned flat cable must be produced for the SSC project. Starting from a specification developed by Lawrence Berkeley Laboratory (LBL), a special cabling machine has been designed by Dour Metal. It has been designed to be able to run at a speed corresponding to a maximum production rate of 10 m/min. This cabling machine is the key part of the production line which consists of a precision Turkshead equipped with a variable power drive, a caterpillar, a dimensional control bench, a data acquisition system, and a take-up unit. The main features of the cabling unit to be described are a design with nearly equal path length between spool and assembling point for all the wires, and the possibility to run the machine with several over- or under-twisting ratios between cable and wires. These requirements led Dour Metal to the choice of an unconventional mechanical concept for a cabling machine
20. 29 CFR 1926.956 - Underground lines.
2010-07-01
... 29 Labor 8 2010-07-01 2010-07-01 false Underground lines. 1926.956 Section 1926.956 Labor... Underground lines. (a) Guarding and ventilating street opening used for access to underground lines or... underground facilities, efforts shall be made to determine the location of such facilities and work...
1. Environmental benefits of underground coal gasification.
Liu, Shu-qin; Liu, Jun-hua; Yu, Li
2002-04-01
Environmental benefits of underground coal gasification are evaluated. The results showed that through underground coal gasification, gangue discharge is eliminated, sulfur emission is reduced, and the amount of ash, mercury, and tar discharge are decreased. Moreover, effect of underground gasification on underground water is analyzed and CO2 disposal method is put forward. PMID:12046301
2. Underground storage of radioactive wastes
An introductory survey of the underground disposal of radioactive wastes is given. Attention is paid to various types of radioactive wastes varying from low to highly active materials, as well as mining techniques and salt deposits
3. Arrival directions of underground muons
A geiger counter cosmic ray telescope has been constructed in the Holborn Underground Laboratory, London, to study the arrival directions of cosmic ray muons in the zenith angle range 70 - 900. The apparatus is described and some preliminary results presented
4. ATLAS solenoid operates underground
2006-01-01
A new phase for the ATLAS collaboration started with the first operation of a completed sub-system: the Central Solenoid. Teams monitoring the cooling and powering of the ATLAS solenoid in the control room. The solenoid was cooled down to 4.5 K from 17 to 23 May. The first current was established the same evening that the solenoid became cold and superconductive. 'This makes the ATLAS Central Solenoid the very first cold and superconducting magnet to be operated in the LHC underground areas!', said Takahiko Kondo, professor at KEK. Though the current was limited to 1 kA, the cool-down and powering of the solenoid was a major milestone for all of the control, cryogenic, power and vacuum systems-a milestone reached by the hard work and many long evenings invested by various teams from ATLAS, all of CERN's departments and several large and small companies. Since the Central Solenoid and the barrel liquid argon (LAr) calorimeter share the same cryostat vacuum vessel, this achievement was only possible in perfe...
5. Underground pumped hydroelectric storage
Allen, R.D.; Doherty, T.J.; Kannberg, L.D.
1984-07-01
Underground pumped hydroelectric energy storage was conceived as a modification of surface pumped storage to eliminate dependence upon fortuitous topography, provide higher hydraulic heads, and reduce environmental concerns. A UPHS plant offers substantial savings in investment cost over coal-fired cycling plants and savings in system production costs over gas turbines. Potential location near load centers lowers transmission costs and line losses. Environmental impact is less than that for a coal-fired cycling plant. The inherent benefits include those of all pumped storage (i.e., rapid load response, emergency capacity, improvement in efficiency as pumps improve, and capacity for voltage regulation). A UPHS plant would be powered by either a coal-fired or nuclear baseload plant. The economic capacity of a UPHS plant would be in the range of 1000 to 3000 MW. This storage level is compatible with the load-leveling requirements of a greater metropolitan area with population of 1 million or more. The technical feasibility of UPHS depends upon excavation of a subterranean powerhouse cavern and reservoir caverns within a competent, impervious rock formation, and upon selection of reliable and efficient turbomachinery - pump-turbines and motor-generators - all remotely operable.
6. LUNA: Nuclear Astrophysics Deep Underground
Broggini, Carlo; Bemmerer, Daniel; Guglielmetti, Alessandra; Menegazzo, Roberto
2010-01-01
Nuclear astrophysics strives for a comprehensive picture of the nuclear reactions responsible for synthesizing the chemical elements and for powering the stellar evolution engine. Deep underground in the Gran Sasso laboratory the cross sections of the key reactions of the proton-proton chain and of the Carbon-Nitrogen-Oxygen (CNO) cycle have been measured right down to the energies of astrophysical interest. The salient features of underground nuclear astrophysics are summarized here. The mai...
7. Parametrically excited oscillation of stay cable and its control in cable-stayed bridges
孙炳楠; 汪至刚; 高赞明; 倪一清
2003-01-01
This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.
8. Condition Monitoring of Cables Task 3 Report: Condition Monitoring Techniques for Electric Cables
Villaran, M.; Lofaro, R.; na
2009-11-30
For more than 20 years the NRC has sponsored research studying electric cable aging degradation, condition monitoring, and environmental qualification testing practices for electric cables used in nuclear power plants. This report summarizes several of the most effective and commonly used condition monitoring techniques available to detect damage and measure the extent of degradation in electric cable insulation. The technical basis for each technique is summarized, along with its application, trendability of test data, ease of performing the technique, advantages and limitations, and the usefulness of the test results to characterize and assess the condition of electric cables.
9. Chinese Market for Fibres and Cables
Yuxing Zhao
2003-01-01
This article presents a summary of Chinese market of optical fibres and cables based on the development of the optical communications industry. Analysis shows that the market will keep growing for sometime in the future.
10. 3-D Numerical Simulations of Twisted Stacked Tape Cables
Krüger, Philipp A. C.; Zermeño, Victor M. R.; Takayasu, Makoto; Grilli, Francesco
2014-01-01
Different magnet applications require compact high current cables. Among the proposed solutions, the Twisted Stacked Tape Cable (TSTC) is easy to manufacture and has very high tape length usage efficiency. In this kind of cables the tapes are closely packed, so that their electromagnetic interaction is very strong and determines the overall performance of the cable. Numerical models are necessary tools to precisely evaluate this interaction and to predict the cable's behavior, e.g. in terms o...
11. Experimental Simulation of Wet-Snow Shedding from Sagged Cables
Fonyó, András; Kollar, László E.; Farzaneh, Masoud; Montpellier, Patrice
2009-01-01
The process of wet-snow shedding from overhead cables was simulated in cold-chamber experiments under different ambient conditions. The main objective of the study was to examine how cable sag influences the snow-shedding process. However, the effects of several other parameters were also considered, such as air temperature, solar radiation, snow-sleeve length, and periodic excitation of the cable. Periodic excitation was applied at the suspension point of the cable, leading to cable vibratio...
12. High frequency characteristics of medium voltage XLPE power cables
Mugala, Gavita
2005-01-01
The response of a cable can be used to analyze the variation of the material characteristics along its length. For diagnosis of possible ageing, it is necessary to know how cable design, material properties and cable insulation ageing affects the wave propagation. A cable model has therefore been worked out based upon the high frequency properties of the cable insulation and conductor systems. The high frequency characteristics of the semi-conducting screens, new and water-tree aged cross-lin...
13. Sustainable underground space development in Hong Kong
Xu, Xiaoxiao; 徐笑晓
2014-01-01
Underground space development is regarded as an effective approach to promote a quality living environment in compact city. In Hong Kong, urban underground space developed by private sectors seems not well organized. Besides, underground use in HK can be multifunctional. Thirdly, inner design in some underground spaces is not desirable and lacks vibrancy. Fourthly, underground space development in HK lacks governmental incentives. Last but not least, the regulations and legal loophole on prop...
14. Electrical Cable Bacteria Save Marine Life
Nielsen, Lars Peter
2016-01-01
Animals at the bottomof the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron ‘carpet’, trapping toxic hydrogen sulfide.......Animals at the bottomof the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron ‘carpet’, trapping toxic hydrogen sulfide....
15. Cable system transients theory, modeling and simulation
Ametani, Akihiro; Nagaoka, Naoto
2015-01-01
A systematic and comprehensive introduction to electromagnetic transient in cable systems, written by the internationally renowned pioneer in this field Presents a systematic and comprehensive introduction to electromagnetic transient in cable systems Written by the internationally renowned pioneer in the field Thorough coverage of the state of the art on the topic, presented in a well-organized, logical style, from fundamentals and practical applications A companion website is available
16. Ecology: Electrical Cable Bacteria Save Marine Life
Nielsen, Lars Peter
2016-01-01
Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide.......Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide....
17. Characteristic analysis of DC electric railway systems with superconducting power cables connecting power substations
The application of superconducting power cables to DC electric railway systems has been studied. It could leads to an effective use of regenerative brake, improved energy efficiency, effective load sharing among the substations, etc. In this study, an electric circuit model of a DC feeding system is built and numerical simulation is carried out using MATLAB-Simulink software. A modified electric circuit model with an AC power grid connection taken into account is also created to simulate the influence of the grid connection. The analyses have proved that a certain amount of energy can be conserved by introducing superconducting cables, and that electric load distribution and concentration among the substations depend on the substation output voltage distribution.
18. Specialized video systems for use in underground storage tanks
The Robotics Development Groups at the Savannah River Site and the Hanford site have developed remote video and photography systems for deployment in underground radioactive waste storage tanks at Department of Energy (DOE) sites as a part of the Office of Technology Development (OTD) program within DOE. Figure 1 shows the remote video/photography systems in a typical underground storage tank environment. Viewing and documenting the tank interiors and their associated annular spaces is an extremely valuable tool in characterizing their condition and contents and in controlling their remediation. Several specialized video/photography systems and robotic End Effectors have been fabricated that provide remote viewing and lighting. All are remotely deployable into and from the tank, and all viewing functions are remotely operated. Positioning all control components away from the facility prevents the potential for personnel exposure to radiation and contamination. Overview video systems, both monaural and stereo versions, include a camera, zoom lens, camera positioner, vertical deployment system, and positional feedback. Each independent video package can be inserted through a 100 mm (4 in.) diameter opening. A special attribute of these packages is their design to never get larger than the entry hole during operation and to be fully retrievable. The End Effector systems will be deployed on the large robotic Light Duty Utility Arm (LDUA) being developed by other portions of the OTD-DOE programs. The systems implement a multi-functional ''over the coax'' design that uses a single coaxial cable for all data and control signals over the more than 900 foot cable (or fiber optic) link
19. Carbon Fiber Reinforced Polymer for Cable Structures—A Review
Yue Liu
2015-10-01
Full Text Available Carbon Fiber Reinforced Polymer (CFRP is an advanced composite material with the advantages of high strength, lightweight, no corrosion and excellent fatigue resistance. Therefore, unidirectional CFRP has great potential for cables and to replace steel cables in cable structures. However, CFRP is a typical orthotropic material and its strength and modulus perpendicular to the fiber direction are much lower than those in the fiber direction, which brings a challenge for anchoring CFRP cables. This paper presents an overview of application of CFRP cables in cable structures, including historical review, state of the art and prospects for the future. After introducing properties of carbon fibers, mechanical characteristics and structural forms of CFRP cables, existing CFRP cable structures in the world (all of them are cable bridges are reviewed. Especially, their CFRP cable anchorages are presented in detail. New applications for CFRP cables, i.e., cable roofs and cable facades, are also presented, including the introduction of a prototype CFRP cable roof and the conceptual design of a novel structure—CFRP Continuous Band Winding System. In addition, other challenges that impede widespread application of CFRP cable structures are briefly introduced.
20. Environmental assessment of submarine power cables
Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar
1. Environmental assessment of submarine power cables
Isus, Daniel; Martinez, Juan D. [Grupo General Cable Sistemas, S.A., 08560-Manlleu, Barcelona (Spain); Arteche, Amaya; Del Rio, Carmen; Madina, Virginia [Tecnalia Research and Innovation, 20009 San Sebastian (Spain)
2011-03-15
Extensive analyses conducted by the European Community revealed that offshore wind energy have relatively benign effects on the marine environment by comparison to other forms of electric power generation [1]. However, the materials employed in offshore wind power farms suffer major changes to be confined to the marine environment at extreme conditions: saline medium, hydrostatic pressure... which can produce an important corrosion effect. This phenomenon can affect on the one hand, to the material from the structural viewpoint and on the other hand, to the marine environment. In this sense, to better understand the environmental impacts of generating electricity from offshore wind energy, this study evaluated the life cycle assessment for some new designs of submarine power cables developed by General Cable. To achieve this goal, three approaches have been carried out: leaching tests, eco-toxicity tests and Life Cycle Assessment (LCA) methodologies. All of them are aimed to obtaining quantitative data for environmental assessment of selected submarine cables. LCA is a method used to assess environmental aspects and potential impacts of a product or activity. LCA does not include financial and social factors, which means that the results of an LCA cannot exclusively form the basis for assessment of a product's sustainability. Leaching tests results allowed to conclude that pH of seawater did not significantly changed by the presence of submarine three-core cables. Although, it was slightly higher in case of broken cable, pH values were nearly equals. Concerning to the heavy metals which could migrate to the aquatic medium, there were significant differences in both scenarios. The leaching of zinc is the major environmental concern during undersea operation of undamaged cables whereas the fully sectioned three-core cable produced the migration of significant quantities of copper and iron apart from the zinc migrated from the galvanized steel. Thus, the tar
2. A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants
Sakamuri, Jayachandra N.; Nicolaos Antonio CUTULULIS; Rather, Zakir Hussain; Rimez, Johan
2015-01-01
This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC-HVDC) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, th...
3. AC power supply systems
An ac power supply system includes a rectifier fed by a normal ac supply, and an inverter connected to the rectifier by a dc link, the inverter being effective to invert the dc output of the receiver at a required frequency to provide an ac output. A dc backup power supply of lower voltage than the normal dc output of the rectifier is connected across the dc link such that the ac output of the rectifier is derived from the backup supply if the voltage of the output of the inverter falls below that of the backup supply. The dc backup power may be derived from a backup ac supply. Use in pumping coolant in nuclear reactor is envisaged. (author)
4. Measurement of AC losses in different former materials
Olsen, Søren Krüger; Træholt, Chresten; Kühle, Anders Van Der Aa;
1998-01-01
A high temperature superconducting cable may be based on a centrally located cylindrical support, a so-called former. If electrically conductive, the former can contribute to the AC losses through eddy current losses caused by unbalanced axial and tangential magnetic fields. With these measurements...... we aim at investigating the eddy current losses of commonly used former materials. A one layer cable conductor was wound on a glass fibre reinforced polymer (GRFP) former. By inserting a variety of materials into this, it was possible to measure the eddy current losses of each of the former...... candidates separately; for example copper tubes, stainless steel braid, copper braid, corrugated stainless steel tubes, etc. The measured data are compared with the predictions of a theoretical model. Our results show that in most cases, the losses induced by eddy currents in the former are negligible...
5. Measurement of AC losses in different former materials
Olsen, Søren Krüger; Træholt, Chresten; Kühle, Anders Van Der Aa;
1998-01-01
candidates separately; for example copper tubes, stainless steel braid, copper braid, corrugated stainless steel tubes, etc. The measured data are compared with the predictions of a theoretical model. Our results show that in most cases, the losses induced by eddy currents in the former are negligible......A high temperature superconducting cable may be based on a centrally located cylindrical support, a so-called former. If electrically conductive, the former can contribute to the AC losses through eddy current losses caused by unbalanced axial and tangential magnetic fields. With these measurements...... we aim at investigating the eddy current losses of commonly used former materials. A one layer cable conductor was wound on a glass fibre reinforced polymer (GRFP) former. By inserting a variety of materials into this, it was possible to measure the eddy current losses of each of the former...
6. Modelling ac ripple currents in HTS coated conductors
Xu, Zhihan; Grilli, Francesco
2015-10-01
Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc
7. Application study on the first cable-stayed bridge with CFRP cables in China
Kuihua Mei
2015-08-01
Full Text Available In order to push forward the development of CFRP cable-stayed bridge and accumulate experiences, the study on the application of the first cable-stayed bridge with CFRP cables in China was carried out. The design essentials of main components of the bridge were introduced and its integral performances, including static properties, dynamic properties and seismic response were analyzed using finite element method. A new bond-type anchorage was developed and the processes of fabricating and installing CFRP cables were elaborated. Based on the results of construction simulation, a tension scheme for bridge was propound. During constructing, the stresses and displacement of girder and pylon, as well as the forces and stresses of cables, were tested. The results indicate that all sections of the bridge could meet the requirements of the ultimate bearing capacity and normal service; the performance of the anchorage is good and the stresses in each cable system are similar; the tested values accord well with the calculated values. Further, creep deformation of the resin in anchorages under service load is not obvious. All these results demonstrate that the first application of CFRP cables in the cable-stayed bridge in China is successful.
8. Underground disposal of radioactive wastes
This report is an overview document for the series of IAEA reports dealing with underground waste disposal to be prepared in the next few years. It provides an introduction to the general considerations involved in implementing underground disposal of radioactive wastes. It suggests factors to be taken into account for developing and assessing waste disposal concepts, including the conditioned waste form, the geological containment and possible additional engineered barriers. These guidelines are general so as to cover a broad range of conditions. They are generally applicable to all types of underground disposal, but the emphasis is on disposal in deep geological formations. Some information presented here may require slight modifications when applied to shallow ground disposal or other types of underground disposal. Modifications may also be needed to reflect local conditions. In some specific cases it may be that not all the considerations dealt with in this book are necessary; on the other hand, while most major considerations are believed to be included, they are not meant to be all-inclusive. The book primarily concerns only underground disposal of the wastes from nuclear fuel cycle operations and those which arise from the use of isotopes for medical and research activities
9. Earthquake observation at underground cavern
The earthquake observation has been examined at a cylindrical type cavern hydroelectric power station of 15 m in diameter, 22 m in depth in rock mass in purpose of evaluating the earthquake resistance of semi-underground nuclear power plants. The behavior of the cylindrical cavern has been analysed by fourty-three observed seismic waves. And following results were obtained. (1) Ratios of cavern buttom maximum accelerations to cavern top maximum accelerations are concentrated in the range from 1/2 to 1. This shows that the accelerations are declined at underground. (2) The decline ratios of on-ground spectrum amplitude to the underground at the earthquakes of less than 100 km epicentral distance with shorter predominant periods are generally larger than these at the earthquakes of more than 100 km epicentral distance with longer predominant periods. (3) The peak periods of normalized response spectrum at underground tend to be longer as the epicentral distances are longer. This phenominons of underground are similar to the on-ground. (author)
10. Generalized cable theory for neurons in complex and heterogeneous media
Bédard, Claude; Destexhe, Alain
2013-08-01
Cable theory has been developed over the last decade, usually assuming that the extracellular space around membranes is a perfect resistor. However, extracellular media may display more complex electrical properties due to various phenomena, such as polarization, ionic diffusion, or capacitive effects, but their impact on cable properties is not known. In this paper, we generalize cable theory for membranes embedded in arbitrarily complex extracellular media. We outline the generalized cable equations, then consider specific cases. The simplest case is a resistive medium, in which case the equations recover the traditional cable equations. We show that for more complex media, for example, in the presence of ionic diffusion, the impact on cable properties such as voltage attenuation can be significant. We illustrate this numerically, always by comparing the generalized cable to the traditional cable. We conclude that the nature of intracellular and extracellular media may have a strong influence on cable filtering as well as on the passive integrative properties of neurons.
11. Cable condition monitoring in a pressurized water reactor environment
Oconee Nuclear Station is the first nuclear plant designed, engineered and constructed by Duke Power Company. Even though the accelerated aging method was available to determine the life expectancy of the cable used in the reactor building, no natural aging data was available at that time. In order to be able to verify the condition of the reactor building cable over the life of the plant, an on-going cable monitoring plan was instituted. Various types of cable were selected to be monitored, and they were installed in cable life evaluation circuits in the reactor building. At five year intervals over the life of the plant, cable samples would be removed from these cable life evaluation circuits and tested to determine the effects of the reactor building environment on the integrity of the cable. A review of the cable life evaluation circuits and the results of the evaluation program to date is presented
12. Ship nuclear power device of cable aging management
Cable for marine nuclear power plant continuous delivery of electrical energy. Cable is mostly in the high temperature and strong radiation and harsh working environment, and can not be replaced in the lifetime This should be the cable aging management methods through research, maintenance and repair program to provide a scientific basis. Cable aging management approach for a number of different levels of cable management at different levels, relying on computers and other modern tools, the use of information management database software maintenance of the cable through the science of aging control. Cable Aging Management including the scope of cable aging management, classification management basis and used for different levels of management supervision and implementation of means testing approach. Application of the ship that has the operational management science, both planned maintenance to improve the science, but also improves the efficiency of aging management. This management method can be extended to nuclear power plants of cable aging management. (authors)
13. Underground facility plan for Horonobe Underground Research Laboratory project
The basic and most important conditions in forming plans for designing and constructing an underground research facility are ensuring the safety of the facility construction and securing an environment conductive to research. The site presently designated for construction an underground research facility is in a sedimentary soft rock (mudstone) of Neogene period, found to contain methane gas. Evaluating measures to deal with the geological characteristics, including assessment of the stability of support and handling of methane gas, is important in guaranteeing the safety of construction and operation of the research facility once completed. (author)
14. Full-scale fire experiments on vertical horizontal cable trays
Two full-scale fire experiments on PVC cables used in nuclear power plants were carried out, one with cables in vertical position and one with cables in horizontal position. The vertical cable bundle, 3 m high, 300 mm wide and 30 mm thick, was attached to a steel cable ladder. The vertical bundle experiment was carried out in nearly free space with three walls near the cable ladder guiding air flow in order to stabilise flames. The horizontal cable experiment was carried out in a small room with five cable bundles attached to steel cable ladders. Three of the 2 m long cable bundles were located in an array, equally spaced above each other near one long side of the room and two correspondingly near the opposite long side. The vertical cable bundle was ignited with a small propane gas burner beneath the lower edge of the bundle. The horizontal cable bundles were ignited with a small propane burner beneath the lowest bundle in an array of three bundles. Rate of heat release by means of oxygen consumption calorimetry, mass change, CO2, CO and smoke production rate and gas, wall and cable surface temperatures were measured as a function of time, as well as time to sprinkler operation and failure of test voltage in cables. Additionally, the minimum rate of heat release needed to ignite the bundle was determined. This paper concentrates on describing and recording the experimental set-up and the data obtained. (orig.)
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16. Cable support for electric poles. Support de cables pour poteau electrique
Bourrieres, P.
1989-11-21
The cable support according to this invention comprises a central body of insulating material upon which are mounted individual cable supports and means for connecting the central body to a pole. In this manner, a support designed to support a plurality of cables is realized in a single operation. On the other hand, the placing of the cable support is carried out by a single operation of connecting the central body to the pole, allowing provision for mounting a cable support after erecting the pole, or in additions, a quick repair by transferring the central body from the broken end fo a pole to a new pole or to the trunk of the pole for a temporary restoration of electrical service.
17. HTS cables open the window for large-scale renewables
Geschiere, A.; Willén, D.; Piga, E.; Barendregt, P.
2008-02-01
In a realistic approach to future energy consumption, the effects of sustainable power sources and the effects of growing welfare with increased use of electricity need to be considered. These factors lead to an increased transfer of electric energy over the networks. A dominant part of the energy need will come from expanded large-scale renewable sources. To use them efficiently over Europe, large energy transits between different countries are required. Bottlenecks in the existing infrastructure will be avoided by strengthening the network. For environmental reasons more infrastructure will be built underground. Nuon is studying the HTS technology as a component to solve these challenges. This technology offers a tremendously large power transport capacity as well as the possibility to reduce short circuit currents, making integration of renewables easier. Furthermore, power transport will be possible at lower voltage levels, giving the opportunity to upgrade the existing network while re-using it. This will result in large cost savings while reaching the future energy challenges. In a 6 km backbone structure in Amsterdam Nuon wants to install a 50 kV HTS Triax cable for a significant increase of the transport capacity, while developing its capabilities. Nevertheless several barriers have to be overcome.
18. Evaluation of cable ageing in Nuclear Power Plants; Evaluacion del envejecimiento de cables en centrales nucleares
Lopez Vergara, T. [Empresarios Agrupados, A. I. E. Madrid (Spain); Alonso Chicote, J. [TECNATOM, S. A. (Spain); Burnay, S. [AEA Technology (UK)
2000-07-01
The majority of power, control and instrumentation cables in nuclear power plants use polymers as their basic material for insulation and jacket. In many cases, these cables form part of safety-related circuits and should therefore be capable of operating correctly under both normal and accident conditions. Since polymeric materials are degraded by the long term action of the radiation and thermal environments found in the plant, it is important to be able to establish the cable condition during the plant lifetime. Nowadays there are a number of different methods to evaluate the remaining lifetime of cables. In the case of new plants, or new cables in old plants, accelerated ageing tests and predictive models can be used to establish the behaviour of the cable materials under operating conditions. There are verified techniques and considerable experience in the definition of predictive models. This type of approach is best carried out during the commissioning stage or in the early stages of operation. In older plants, particularly where there is a wide range of cable types in use, it is more appropriate to use condition monitoring methods to establish the state of degradation of cables in-plant. Over the last 10 years there have been considerable developments in methods for condition monitoring of cables and a tool-box of practical techniques are now available. There is no single technique which is suitable for all cable materials but the range of methods covers nearly all of the types currently in use, at present, the most established methods are the indented, thermal analysis (OIT, OITP and TGA) and dielectric loss measurements, All of these are either non-destructive methods or require only micro-samples of material. (Author) 15 refs.
19. Nonlinear Dielectric Response of Water Treed XLPE Cable Insulation
Hvidsten, Sverre
1999-07-01
Condition assessment of XLPE power cables is becoming increasingly important for the utilities, due to a large number of old cables in service with high probability of failure caused by water tree degradation. The commercial available techniques are generally based upon measurements of the dielectric response, either by time (polarisation/depolarisation current or return voltage) or frequency domain measurements. Recently it has been found that a high number of water trees in XLPE insulated cables causes the dielectric response to increase more than linearly with increasing test voltage. This nonlinear feature of water tree degraded XLPE insulation has been suggested to be of a great importance, both for diagnostic purposes, and for fundamental understanding of the water tree phenomenon itself. The main purpose of this thesis have been to study the nonlinear feature of the dielectric response measured on watertreed XLPE insulation. This has been performed by dielectric response measurements in both time and frequency domain, numerical calculations of losses of simplified water tree models, and fmally water content and water permeation measurements on single water trees. The dielectric response measurements were performed on service aged cable samples and laboratory aged Rogowski type objects. The main reason for performing laboratory ageing was to facilitate diagnostic testing as a function of ageing time of samples containing mainly vented water trees. A new method, based upon inserting NaC1 particles at the interface between the upper semiconductive screen and the insulation, was found to successfully enhance initiation and growth of vented water trees. AC breakdown strength testing show that it is the vented water trees that reduce the breakdown level of both the laboratory aged test objects and service aged cable samples. Vented water treeing was found to cause the dielectric response to become nonlinear at a relatively low voltage level. However, the measured
20. High voltage pulsed cable design: a practical example
The design of optimum high voltage pulse cable is difficult because very little emperical data are available on performance in pulsed applications. This paper follows the design and testing of one high voltage pulse cable, 40/100 trigger cable. The design was based on an unproven theory and the impressive outcome lends support to the theory. The theory is outlined and it is shown that there exists an inductance which gives a cable of minimum size for a given maximum stress. Test results on cable manufactured according to the design are presented and compared with the test results on the cable that 40/100 replaces
1. CSNS control cable information management system based on web
This paper presents an approach to data modeling a great number of control devices and cables with complicated relations of CSNS (China Spallation Neutron Source). The CSNS accelerator control cable database was created using MySQL, and the control cable information management system based on Web was further built. During the development of the database, the design idea of IRMIS database was studied. and the actual situation of CSNS accelerator control cables was investigated. The control cable database model fitting the requirements was designed. This system is of great convenience to manage and maintain CSNS control devices and cables in the future. (authors)
2. Cable condition monitoring research activities at Sandia National Laboratories
Sandia National Laboratories is currently conducting long-term aging research on representative samples of nuclear power plant cables. The objectives of this program are to determine the suitability of these cables for extended life (beyond 40 year design basis) and to assess various cable condition monitoring techniques for predicting remaining cable life. The cables are being aged for long times at relatively mild exposure conditions with various condition monitoring techniques to be employed during the aging process. Following the aging process, the cables will be exposed to a sequential accident profile consisting of high dose rate irradiation followed by a simulated design basis loss-of-coolant accident (LOCA) steam exposure
3. Energy losses of superconducting power transmission cables in the grid
Østergaard, Jacob; Okholm, Jan; Lomholt, Karin;
2001-01-01
One of the obvious motives for development of superconducting power transmission cables is reduction of transmission losses. Loss components in superconducting cables as well as in conventional cables have been examined. These losses are used for calculating the total energy losses of conventional...... as well as superconducting cables when they are placed in the electric power transmission network. It is concluded that high load connections are necessary to obtain energy saving by the use of HTSC cables. For selected high load connections, an energy saving of 40% is expected. It is shown that the...... thermal insulation and cooling machine efficiency are the most important loss element in a superconducting cable system...
4. NEPO cable system aging management programs
Full text: Cable polymer aging and condition monitoring is being studied in detail under the Nuclear Energy Plant Optimization Program (NEPO) that is co-sponsored by the U.S. Department of Energy and EPRI. Significant advances in modeling of polymer aging and condition monitoring have occurred and continue to be developed. The activities include: Analysis of the linearity of the Arrhenius model to room temperature; Development of a wear-out technique for determining remaining life of cable polymers; Determination of the aging fragility point for composite EPR/CSPE insulation with respect to LOCA function; Development of visual/tactile training aids for cable assessment; Development of a totally new nuclear magnetic resonance condition monitoring technique; Assessment of existing techniques with regard to repeatability, accuracy and ease of use. Through use of highly precise oxygen consumption experiments, the linearity of the Arrhenius model is being evaluated. In these experiments, polymer is placed in vials with a known amount of oxygen and aged at much lower temperatures than is possible with standard accelerated aging techniques. aging results are possible at room temperature. The technique is being applied to commonly used insulation and jacket polymers. The wear-out technique allows highly non-linear aging behavior to be made linear. The wearout point of a polymer is determined through high-rate aging and use of a condition monitoring technique to establish the end point. Then, micro-samples of cable that have been naturally aged are subjected to high rate aging to the same end point. The ratio of the remaining high rate aging period to the total high rate aging time provides a linear indication of the remaining service time. Initial screening of nuclear plant cable systems can use visual/tactile techniques to identify cable that has aged significantly. Training aids have been developed by developing sets of specimens with accelerated aging ranging from none
5. Storage of high-level wastes, investigations in underground laboratories
This article reviews the different collaborations made by ANDRA (national agency for the management of radioactive wastes) in the fields of underground radioactive waste storage. ANDRA has taken part in various experimental research programs performed in laboratories such as Mol in Belgium, Aspo in Sweden, Pinawa in Canada and Grimsel in Switzerland. This article details the experiments led at Mol since 1984. ANDRA is commissioned by the 30.12.91 decree to study the possibility of storage in deep geological layers. A thorough knowledge of the matter requires the building of underground laboratories in order to test and validate technological choices on a real scale. 6 themes will have to be investigated: 1) the capacity to seal up the storage facility after its use in order to assure the protection of man and environment, 2) the effects of geological perturbations on the confining properties of the site, 3) the confining ability of the Callovian-Oxfordian geological formation, 4) the transfer of radionuclides from the geological formation to the biosphere, 5) the constructing possibility of an underground storage facility, and 6) the possibility of retrieving the stored packages. (A.C.)
6. Dynamic Underground Stripping Demonstration Project
LLNL is collaborating with the UC Berkeley College of Engineering to develop and demonstrate a system of thermal remediation and underground imaging techniques for use in rapid cleanup of localized underground spills. Called ''Dynamic Stripping'' to reflect the rapid and controllable nature of the process, it will combine steam injection, direct electrical heating, and tomographic geophysical imaging in a cleanup of the LLNL gasoline spill. In the first 8 months of the project, a Clean Site engineering test was conducted to prove the field application of the techniques before moving to the contaminated site in FY 92
7. HTS twisted stacked-tape cable conductor
The feasibility of high field magnet applications of the twisted stacked-tape cabling method with 2G YBCO tapes has been investigated. An analysis of torsional twist strains of a thin HTS tape has been carried out taking into account the internal shortening compressive strains accompanied with the lengthening tensile strains due to the torsional twist. The model is benchmarked against experimental tests using YBCO tapes. The critical current degradation and current distribution of a four-tape conductor was evaluated by taking account of the twist strain, the self-field and the termination resistances. The critical current degradation for the tested YBCO cables can be explained by the perpendicular self-field effect. It is shown that the critical current of a twisted stacked-tape conductor with a four-tape cable does not degrade with a twist pitch length as short as 120 mm. Current distribution among tapes and hysteresis losses are also investigated. A compact joint termination method for a 2G YBCO tape cable has been developed. The twisted stacked-tape conductor method may be an attractive means for the fabrication of highly compact, high current cables from multiple flat HTS tapes.
8. AC1 Wing
Adrian DOBRE
2010-03-01
Full Text Available The AC1 wing replaces the old wing of the wind tunnel model AEROTAXI, which has been made at scale 1:9. The new wing is part of CESAR program and improves the aerodynamic characteristics of the old one. The geometry of the whole wing was given by FOI Sweden and position of AC1 wing must coincide with the structure of the AEROTAXI model.
9. AC1 Wing
Adrian DOBRE
2010-01-01
The AC1 wing replaces the old wing of the wind tunnel model AEROTAXI, which has been made at scale 1:9. The new wing is part of CESAR program and improves the aerodynamic characteristics of the old one. The geometry of the whole wing was given by FOI Sweden and position of AC1 wing must coincide with the structure of the AEROTAXI model.
10. Computer-Aided Engineering Of Cabling
Billitti, Joseph W.
1989-01-01
Program generates data sheets, drawings, and other information on electrical connections. DFACS program, centered around single data base, has built-in menus providing easy input of, and access to, data for all personnel involved in system, subsystem, and cabling. Enables parallel design of circuit-data sheets and drawings of harnesses. Also recombines raw information to generate automatically various project documents and drawings, including index of circuit-data sheets, list of electrical-interface circuits, lists of assemblies and equipment, cabling trees, and drawings of cabling electrical interfaces and harnesses. Purpose of program to provide engineering community with centralized data base for putting in, and gaining access to, functional definition of system as specified in terms of details of pin connections of end circuits of subsystems and instruments and data on harnessing. Primary objective to provide instantaneous single point of interchange of information, thus avoiding
11. Distance and Cable Length Measurement System
Hernández, Sergio Elias; Acosta, Leopoldo; Toledo, Jonay
2009-01-01
A simple, economic and successful design for distance and cable length detection is presented. The measurement system is based on the continuous repetition of a pulse that endlessly travels along the distance to be detected. There is a pulse repeater at both ends of the distance or cable to be measured. The endless repetition of the pulse generates a frequency that varies almost inversely with the distance to be measured. The resolution and distance or cable length range could be adjusted by varying the repetition time delay introduced at both ends and the measurement time. With this design a distance can be measured with centimeter resolution using electronic system with microsecond resolution, simplifying classical time of flight designs which require electronics with picosecond resolution. This design was also applied to position measurement. PMID:22303169
12. Insulation systems for superconducting transmission cables
Tønnesen, Ole
This paper describes shortly the status of superconducting transmission lines and assesses what impact the recently discovered BSCCO superconductors may have on the design of the cables.Two basically different insulation systems are discussed:1) The room temperature dielectric design, where the...... electrical insulation is placed outside both the superconducting tube and the cryostat. The superconducting tube is cooled by liquid nitrogen which is pumped through the hollow part of the tube.2) The cryogenic dielectric design, where the electrical insulation is placed inside the cryostat and thus is kept...... at temperature near 77 K.The optimal design is determined by a loss evaluation in relation to the power transfer capacity of the cable. Development work in progress on the design and construction of superconducting cables in Denmark is described as an example....
13. Aging assessment of nuclear generating station cables
A number of diagnostic techniques requiring small samples (e.g. shavings) for monitoring the condition of nuclear generating station cables have been identified. The cables studied were insulated with cross-linked or unmodified polyethylene, ethylene propylene rubber, butyl rubber, styrene butadiene rubber, and polyvinyl chloride. Specimens were aged at elevated temperatures, or gamma irradiated up to 120 Mrad. The degradation was assessed by conventional elongation measurements, differential scanning calorimetry (DSC), oxidation induction time, DSC oxidation induction temperature (under high oxygen pressure), infrared carbonyl absorption, density, and swelling measurements. The sensitivities of the diagnostic techniques in measuring oxidation and embrittlement were compared with the elongation results, and a criterion for monitoring the cable degradation was developed. Some results presented illustrate the use of the diagnostic techniques in monitoring degradation. 13 refs., 2 tabs., 24 figs
14. Electrothermal Coordination in Cable Based Transmission Grids
Olsen, Rasmus Schmidt; Holbøll, Joachim; Gudmundsdottir, Unnur Stella
2013-01-01
Electrothermal coordination (ETC) is introduced for cable based transmission grids. ETC is the term covering operation and planning of transmission systems based on temperature, instead of current. ETC consists of one part covering the load conditions of the system and one covering the thermal...... behavior of the components. The dynamic temperature calculations of power cables are suggested to be based on thermoelectric equivalents (TEEs). It is shown that the thermal behavior can be built into widely used load flow software, creating a strong ETC tool. ETC is, through two case scenarios, proven to...... be beneficial for both operator and system planner. It is shown how the thermal behavior can be monitored in real-time during normal dynamic load and during emergencies. In that way, ETC enables cables to be loaded above their normal rating, while maintaining high reliability of the system, which...
15. Trackless centre pivot-steered underground vehicle with electric-motor drive. Gleisloses knickgelenktes Untertagefahrzeug mit Elektromotorantrieb
Hillmann, W.; Paus, H.; Drews, E.
1989-05-03
Trackless, centre pivot-steered underground vehicle with electric-motor drive of the tractor section, the supply of energy to which takes place via sliding contact line and a current-collecting device which can be driven thereon, and via a connecting cable which is connected electrically and mechanically to the latter and can be unwound from a reel against a restoring force, characterised by the combination of the following features: (a) the connecting cable (supply cable) is connected to the current-collecting device via a slip-ring member which can be rotated about a vertical axle; (b) a cable reel which winds in a spiral and is driven by a hydraulic motor is mounted on the tractor section so as to be rotatable about a vertical axle, the axle being equipped with a slip-ring member; (c) a hydraulically pivotable guide arm is arranged coaxially to the cable reel; (d) a hydrostatic axial piston transmission for the travelling mechanism and drive in (b) and (c) is coupled to a three phase current motor. 1 fig.
16. Fiberglass underground petroleum storage systems
Fiberglass Reinforced Plastic (FRP) products have been in use for many years in a wide variety of products and markets. The automotive, marine, military, chemical, and petroleum markets have made extensive use of FRP. Today, over 300,000 FRP tanks and over 40,000,000 feet of FRP pipe are in service in petroleum marketing as well as industrial and commercial storage applications. In the early 1960's the American Petroleum Institute invited the FRP industry to design FRP underground tanks to solve their corrosion caused underground leaker problems. The challenge was accepted and in 1965 FRP tanks were introduced to the petroleum storage marketplace. FRP pipe, specifically designed for underground petroleum use, was Underwriter's Laboratories tested and listed and introduced in 1968. These fiberglass tanks and pipe have a 25 year perfect record against both internal and external corrosion. The FRP tank and pipe performance record has been outstanding. Less than 1/2 of 1% have ever been involved in an in-ground failure. When first introduced, FRP tanks carried an initial cost premium of 50 to 100% over unprotected steel. Since all Underground Storage Tank (UST) systems must be corrosion protected, initial FRP costs are now competitive with corrosion protected steel
17. Underground nuclear explosions and earthquakes
The stages that have marked the ways towards the interdiction of nuclear tests are reviewed. Although seismographic equipments have been greatly improved, it is shown that a separate detection of underground nuclear explosions from natural seismic vibrations is still quite uneasy. The use of nuclear loads for civil engineering still makes it more complicate to apply a treatee of interdiction of nuclear tests
18. 30 CFR 72.630 - Drill dust control at underground areas of underground mines.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drill dust control at underground areas of underground mines. 72.630 Section 72.630 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT... dust control at underground areas of underground mines. (a) Dust resulting from drilling in rock...
19. Calorimetric measurements of losses in HTS cables
Tønnesen, Ole; Veje, Niels Erling Winsløv; Rasmussen, Carsten;
2001-01-01
A calorimetric test rig is used to investigate various loss components in a 10 m long superconducting cable model. A calorimetric technique, based on thermocouple measurements, is used to measure the losses of the 10 m long superconducting cable model. The current dependent losses are also measured...... electrically and compared with the losses obtained with the calorimetric method. The results obtained by the two methods are consistent. Based on an I2 (current) fitting procedure, the loss, caused by the eddy current generated in the stainless steel cryostat housing, and the hysteresis loss generated in the...
20. Configuration Synthesis for Fully Restrained 7-Cable-Driven Manipulators
Xiaoqiang Tang
2012-10-01
Full Text Available Cable distribution plays a vital role in Cable Driven Parallel Manipulators (CDPMs regarding tension and workspace quality, especially in fully restrained CDPMs. This paper focuses on three typical configurations of fully restrained CDPMs with 7 cables in order to introduce an approach for configuration synthesis. Firstly, the kinematic models of three types of CDPMs with 7 cables are set up. Then, in order to evaluate workspace quality, two new indices are proposed by using tensions along each cable, which are the All Cable Tension Distribution Index (ACTDI and Global Tension Distribution Index (GTDI. Next, the three types of CDPMs with 7 cables are analysed with the two indices. At the end, according to different performance requirements, the configurations of cable distribution are discussed and selected.
1. Superscreened co-axial cables for the nuclear power industry
This specification covers the requirements of superscreened cables. Part 1 covers general requirements and test methods. Part 2 covers data sheets setting out the electrical and mechanical requirements for each type of cable, together with engineering information. (U.K.)
2. Fault Management of a Cold Dielectric HTS Power Transmission Cable
High temperature superconductor (HTS) power transmission cables offer significant advantages in power density over conventional copper-based cables. As with conventional cables, HTS cables must be safe and reliable when abnormal conditions, such as local and through faults, occur in the power grid. Due to the unique characteristics of HTS power cables, the fault management of an HTS cable is different from that of a conventional cable. Issues, such as nitrogen bubble formation within lapped dielectric material, need to be addressed. This paper reviews the efforts that have been performed to study the fault conditions of a cold dielectric HTS power cable. As a result of the efforts, a fault management scheme has been developed, which provides both local and through faults system protection. Details of the fault management scheme with examples are presented
3. Dynamic Analysis of Towed and Variable Length Cable Systems
WANG Shu-xin; WANG Yan-hui; LI Xiao-ping
2007-01-01
Towed cable systems are frequently used in marine measurements where the length of the towed cable varies during launch and recovery. In this paper a novel method for modeling variable length cable systems is introduced based on the finite segment formulation. The variable length of the towed cable is described by changing the length of the segment near the towing point and by increasing or decreasing the number of the discrete segments of the cable. In this way, the elastic effects of the cable can be easily handled since geometry and material properties of each segment are kept constant. Experimental results show that the dynamic behavior of the towed cable is consistent between the model and the physical cable. Results show that the model provides numerical efficiency and simulation accuracy for the variable length towed system.
4. Basic Requirements for Cables of Systems Important to NPP Safety
In view of the need for equipment upgrades at Ukrainian nuclear power plants, the replacement of cables, as an integral part of any system, becomes important. There is no document in Ukraine that combines requirements for cables of systems important to nuclear safety. The paper systematizes the technical requirements of national regulatory documents on nuclear and radiation safety in relation to cable products. The most important requirements for selecting cables are fire safety, resistance to high temperatures, humidity and pressure, resistance to ionizing radiation, seismic resistance and electromagnetic compatibility. The use of cables in the NPP containment and safety systems imposes on them the most stringent requirements as regards nuclear and radiation safety in plant operation. The paper identifies features and operating conditions for cable lines as part of NPP safety systems and shows the general classification of cable products. Development of a regulatory document to combine requirements for cables of safety systems will facilitate their selection during upgrading.
5. Analysis of Electrical Coupling Parameters in Superconducting Cables
Bottura, L; Rosso, C
2003-01-01
The analysis of current distribution and redistribution in superconducting cables requires the knowledge of the electric coupling among strands, and in particular the interstrand resistance and inductance values. In practice both parameters can have wide variations in cables commonly used such as Rutherford cables for accelerators or Cable-in-Conduits for fusion and SMES magnets. In this paper we describe a model of a multi-stage twisted cable with arbitrary geometry that can be used to study the range of interstrand resistances and inductances that is associated with variations of geometry. These variations can be due to cabling or compaction effects. To describe the variations from the nominal geometry we have adopted a cable model that resembles to the physical process of cabling and compaction. The inductance calculation part of the model is validated by comparison to semi-analytical results, showing excellent accuracy and execution speed.
6. Nonlinear dynamic response of stay cables under axial harmonic excitation
Xu XIE; He ZHAN; Zhi-cheng ZHANG
2008-01-01
This paper proposes a new numerical simulation method for analyzing the parametric vibration of stay cables based on the theory of nonlinear dynamic response of structures under the asynchronous support excitation.The effects of important parameters related to parametric vibration of cables,I.e., characteristics of structure,excitation frequency,excitation amplitude,damping effect of the air and the viscous damping coefficient of the cables,were investigated by using the proposed method for the cables with significant length difference as examples.The analysis results show that nonlinear finite element method is a powerful technique in analyzing the parametric vibration of cables,the behavior of parametric vibration of the two cables with different Irvine parameters has similar properties,the amplitudes of parametric vibration of cables are related to the frequency and amplitude of harmonic support excitations and the effect of distributed viscous damping on parametric vibration of the cables is very small.
7. Urban underground resources management for sustainable development
Li, Huanqing
2010-01-01
Urban problems such as congestions, land scarcity, pollutions, could be alleviated by underground solutions, which are critical underground infrastructues and buildings adaptable to subsurface. An integrated approach of urban underground management is put forward, aiming to research on the feasability of developing valuable subsurface, and to promote the sustainability of resources' multi-usage exploitation.
8. 49 CFR 192.325 - Underground clearance.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Underground clearance. 192.325 Section 192.325... Lines and Mains § 192.325 Underground clearance. (a) Each transmission line must be installed with at least 12 inches (305 millimeters) of clearance from any other underground structure not associated...
9. Deep underground intensities of high energy muons
The experiment of the deep underground emulsion chamber has been started in order to measure the energy spectra of muons deep underground at high energies. Preliminary results based on the emulsion chamber with 0.9 ton of lead are presented. This test exposure has been performed at the vertical depth of 850 hg/cm2 underground in the road tunnel. (orig.)
10. Composite Based EHV AC Overhead Transmission Lines
Sørensen, Thomas Kjærsgaard
Overhead lines at transmission level are the backbone of any national power grid today. New overhead line projects however are at the same time subject to ever greater public resistance due to the lines environmental impact. As full undergrounding of transmission lines at extra high voltage (EHV......) levels are still not seen as possibility, the future expansion of transmission grids are dependent on new solutions with lessened environment impact, especially with regard to the visual impact. In the present Thesis, composite materials and composite based overhead line components are presented and...... analysed with regard to the possibilities, limitations and risks widespread application of composite materials on EHV AC overhead transmission lines may present. To form the basis for evaluation of the useability of composite materials, dierent overhead line projects aimed at reducing the environmental...
11. Broadcast Service Areas, Cable, cable, Published in Not Provided, 1:600 (1in=50ft) scale, Comcast.
NSGIC GIS Inventory (aka Ramona) — This Broadcast Service Areas, Cable dataset, published at 1:600 (1in=50ft) scale as of Not Provided. It is described as 'cable'. Data by this publisher are often...
12. Environmental Impact of a Submarine Cable: Case Study of the Acoustic Thermometry of Ocean Climate (ATOC)/ Pioneer Seamount Cable
Kogan, I.; Paull, C. K.; Kuhnz, L.; von Thun, S.; Burton, E.; Greene, H. G.; Barry, J. P.
2003-12-01
To better understand the potential impacts of the presence of cables on the seabed, a topic of interest for which little data is published or publicly available, a study of the environmental impacts of the ATOC/Pioneer Seamount cable was conducted. The 95 km long, submarine, coaxial cable extends between Pioneer Seamount and the Pillar Point Air Force Station in Half Moon Bay, California. Approximately two thirds of the cable lies within the Monterey Bay National Marine Sanctuary. The cable is permitted to NOAA- Oceanic and Atmospheric Research for transmitting data from a hydrophone array on Pioneer Seamount to shore. The cable was installed unburied on the seafloor in 1995. The cable path crosses the continental shelf, descends to a maximum depth of 1,933 m, and climbs back upslope to 998 m depth near the crest of Pioneer Seamount. A total of 42 hours of video and 152 push cores were collected in 10 stations along cable and control transects using the ROVs Ventana and Tiburon equipped with cable-tracking tools. The condition of the cable, its effect on the seafloor, and distribution of benthic megafauna and infauna were determined. Video data indicated the nature of interaction between the cable and the seafloor. Rocky nearshore areas, where wave energies are greatest, showed the clearest evidence of impact. Here, evidence of abrasion included frayed and unraveling portions of the cable's armor and vertical grooves in the rock apparently cut by the cable. The greatest incision and armor damage occurred on ledges between spans in irregular rock outcrop areas. Unlike the nearshore rocky region, neither the rocks nor the cable appeared damaged along outcrops on Pioneer Seamount. Multiple loops of slack cable added during a 1997 cable repair operation were found lying flat on the seafloor. Several sharp kinks in the cable were seen at 240 m water depths in an area subjected to intense trawling activity. Most of the cable has become buried with time in sediment
13. 47 CFR 76.111 - Cable sports blackout.
2010-10-01
... 47 Telecommunication 4 2010-10-01 2010-10-01 false Cable sports blackout. 76.111 Section 76.111... CABLE TELEVISION SERVICE Network Non-duplication Protection, Syndicated Exclusivity and Sports Blackout § 76.111 Cable sports blackout. (a) No community unit located in whole or in part within the...
14. Working Paper for the Revision of San Francisco's Cable Franchise.
San Francisco Public Library, CA. Video Task Force.
Ideas are presented for the revision of San Francisco's cable franchise. The recommendations in the report are based upon national research of library and urban use of cable communications and are designed to help the city's present and future cable franchises to comply with the regulations of the Federal Communications Commission by March 31,…
15. Estimation of Medium Voltage Cable Parameters for PD Detection
Villefrance, Rasmus; Holbøll, Joachim T.; Henriksen, Mogens
measured signal at the cable terminations to a specific PD-amplitude and location on the cable, the attenuation and the transmission speed of PD-pulses on the cable have to be known. Consequently, the main parameter to be determined is the complex propagation constant which consists of the attenuation and...
16. 47 CFR 32.2426 - Intrabuilding network cable.
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Intrabuilding network cable. 32.2426 Section 32... Intrabuilding network cable. (a) This account shall include the original cost of cables and wires located on the company's side of the demarcation point or standard network interface inside subscribers' buildings...
17. 47 CFR 32.6426 - Intrabuilding network cable expense.
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Intrabuilding network cable expense. 32.6426... Intrabuilding network cable expense. (a) This account shall include expenses associated with intrabuilding network cable. (b) Subsidiary record categories shall be maintained as provided in § 32.2426(a) of...
18. Ground Return Current Behaviour in High Voltage Alternating Current Insulated Cables
Roberto Benato
2014-12-01
Full Text Available The knowledge of ground return current in fault occurrence plays a key role in the dimensioning of the earthing grid of substations and of cable sealing end compounds, in the computation of rise of earth potential at substation sites and in electromagnetic interference (EMI on neighbouring parallel metallic conductors (pipes, handrails, etc.. Moreover, the ground return current evaluation is also important in steady-state regime since this stray current can be responsible for EMI and also for alternating current (AC corrosion. In fault situations and under some assumptions, the ground return current value at a substation site can be computed by means of k-factors. The paper shows that these simplified and approximated approaches have a lot of limitations and only multiconductor analysis can show the ground return current behaviour along the cable (not only the two end values both in steady-state regime and in short circuit occurrence (e.g., phase-to-ground and phase-to-phase-to-ground. Multiconductor cell analysis (MCA considers the cable system in its real asymmetry without simplified and approximated hypotheses. The sensitivity of ground return current on circuit parameters (cross-bonding box resistances, substation earthing resistances, soil resistivity is presented in the paper.
19. Broadband Wireline Provider Service: Cable Modem - Other; BBRI_cableOther12
University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - Other" technology. Broadband availability is...
20. Broadband Wireline Provider Service: Cable Modem - DOCSIS 3.0; BBRI_cableDOCSIS12
University of Rhode Island Geospatial Extension Program — This dataset represents the availability of wireline broadband Internet access in Rhode Island via "Cable Modem - DOCSIS 3.0" technology. Broadband availability is...
1. Overhead lines: materials. Guard conductors and cables; Lignes aeriennes: materiels. Conducteurs et cables de garde
Chanal, A. [Electricite de France (EDF), 75 - Paris (France). Direction de la Production et du Transport; Leveque, J.P. [Electricite de France (EDF), Reseau de Transport d' Electricite, 75 - Paris (France)
2003-02-01
This article presents the characteristics of bare cables for the construction of overhead lines. During the last decades, no important change has been made in the choice of conductive materials. The main materials used are: the high purity cold drawn aluminium in bi-metal aluminium-steel cables, and the 'almelec', an aluminium alloy with a reinforced traction resistance. Recently, new conductors with a higher transport capacity and a better temperature resistance have been developed. Another way of research concerns the combination of conductors and composite materials (carbon fibers) but no satisfactory solutions have been obtained so far. A more important evolution concerns the guard cables for high voltage lines which now include telecommunication circuits (optical fibers) for high flow rate transmission of numerical data. The laying out of such cables has been generalized in France in order to supply the overall territory with equivalent and satisfactory performances. (J.S.)
2. Cooperative Behaviours with Swarm Intelligence in Multirobot Systems for Safety Inspections in Underground Terrains
Chika Yinka-Banjo
2014-01-01
Full Text Available Underground mining operations are carried out in hazardous environments. To prevent disasters from occurring, as often as they do in underground mines, and to prevent safety routine checkers from disasters during safety inspection checks, multirobots are suggested to do the job of safety inspection rather than human beings and single robots. Multirobots are preferred because the inspection task will be done in the minimum amount of time. This paper proposes a cooperative behaviour for a multirobot system (MRS to achieve a preentry safety inspection in underground terrains. A hybrid QLACS swarm intelligent model based on Q-Learning (QL and the Ant Colony System (ACS was proposed to achieve this cooperative behaviour in MRS. The intelligent model was developed by harnessing the strengths of both QL and ACS algorithms. The ACS optimizes the routes used for each robot while the QL algorithm enhances the cooperation between the autonomous robots. A description of a communicating variation within the QLACS model for cooperative behavioural purposes is presented. The performance of the algorithms in terms of without communication, with communication, computation time, path costs, and the number of robots used was evaluated by using a simulation approach. Simulation results show achieved cooperative behaviour between robots.
3. Insulation system for high temperature superconductor cables
Michael, P. C.; Haight, A. E.; Bromberg, L.; Kano, K.
2015-12-01
Large-scale superconductor applications, like fusion magnets, require high-current capacity conductors to limit system inductance and peak operating voltage. Several cabling methods using high temperature superconductor (HTS) tapes are presently under development so that the unique high-field, high-current-density, high operating temperature characteristics of 2nd generation REBCO coated conductors can be utilized in next generation fusion devices. Large-scale magnets are generally epoxy impregnated to support and distribute electromagnetic stresses through the magnet volume. However, the present generation of REBCO coated conductors are prone to delamination when tensile stresses are applied to the broad surface of REBCO tapes; this can occur during epoxy cure, cooldown, or magnet energization. We present the development of an insulation system which effectively insulates HTS cabled conductors at high withstand voltage while simultaneously preventing the intrusion of the epoxy impregnant into the cable, eliminating degradation due to conductor delamination. We also describe a small-scale coil test program to demonstrate the cable insulation scheme and present preliminary test results.
4. Modeling of Pressure Effects in HVDC Cables
Szabo, Peter; Hassager, Ole; Strøbech, Esben
1999-01-01
A model is developed for the prediction of pressure effects in HVDC mass impregnatedcables as a result of temperature changes.To test the model assumptions, experiments were performed in cable like geometries.It is concluded that the model may predict the formation of gas cavities....
5. Dynamic Loadability of Cable Based Transmission Grids
Olsen, Rasmus Schmidt
supervised 2 master projects, as well as 5 special courses at DTU. Furthermore I created and taught a cable course, with approximately 25 students, throughout 13 weeks during the spring of 2011. The PhD project has until now contributed with 3 journal papers and 4 conference papers. Selected papers can be...
6. Dutch VULA consumer market services over Cable
Anoniem
2015-01-01
KPN offers a virtual unbundled local access wholesale service over its DSL infrastructure. This offer has been accepted by the Dutch Authority Consumer Market. In the report, it is argued that for consumer market services, the Dutch cable providers can develop an equivalent wholesale service from th
7. Study on Impedance Characteristics of Aircraft Cables
Weilin Li
2016-01-01
Full Text Available Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin and voltage frequency (variable frequency power supply will be adopted for next generation aircraft will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF aircraft electric power system.
8. History of cable-stayed bridges
Gimsing, Niels Jørgen
1999-01-01
The principle of supporting a bridge deck by inclined tension members leading to towers on either side of the span has been known for centuries. However, the real development of cable-stayed bridges did not begin before the 1950s. Since then the free span has been increased from 183 m in the Strö...
9. Integration of HTS Cables in the Future Grid of the Netherlands
Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Aanhaanen, G.; Melnik, I.; Geschiere, A.
Due to increasing power demand, the electricity grid of the Netherlands is changing. The future transmission grid will obtain electrical power generated by decentralized renewable sources, together with large scale generation units located at the coastal region. In this way electrical power has to be distributed and transmitted over longer distances from generation to end user. Potential grid issues like: amount of distributed power, grid stability and electrical loss dissipation merit particular attention. High temperature superconductors (HTS) can play an important role in solving these grid problems. Advantages to integrate HTS components at transmission voltages are numerous: more transmittable power together with less emissions, intrinsic fault current limiting capability, lower ac loss, better control of power flow, reduced footprint, less magnetic field emissions, etc. The main obstacle at present is the relatively high price of HTS conductor. However as the price goes down, initial market penetration of several HTS components (e.g.: cables, fault current limiters) is expected by year 2015. In the full paper we present selected ways to integrate EHV AC HTS cables depending on a particular future grid scenario in the Netherlands.
10. Possibility of high level waste underground disposal
The possibility that the high level wastes disposed underground return to the biosphere again is the dissolution and transport of radioactive nuclides by underground water. As the strata suitable to underground disposal, rock salt strata without underground water, and granite or shale strata in which the movement of underground water is slight are enumerated as the candidates. Wastes are formed into solidified bodies like glass, moreover the technical measures such as canisters and overpacks are applied, therefore even if underground water intrudes into the places of disposal, radioactive nuclides can be contained for considerable time. At the time of selecting the most suitable stratum and designing and evaluating the place of disposal to construct the underground disposal system with high potential for high level wastes, it is necessary to predict the movement of radioactive nuclides from the dissolution into underground water to the return to the biosphere. The potential danger of high level wastes, the danger of high level wastes disposed underground, the effect of isolation distance (the thickness of strata), and the comparison of the danger due to uranium ore and slag and the places of underground disposal are explained. The danger due to uranium ore and slag occurs early and lasts long, and is 1000 times as dangerous as the high level wastes disposed underground. (Kako, I.)
11. Cable deformation simulation and a hierarchical framework for Nb{sub 3}Sn Rutherford cables
Arbelaez, D; Prestemon, S O; Ferracin, P; Godeke, A; Dietderich, D R; Sabbi, G, E-mail: [email protected] [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)
2010-06-01
Knowledge of the three-dimensional strain state induced in the superconducting filaments due to loads on Rutherford cables is essential to analyze the performance of Nb{sub 3}Sn magnets. Due to the large range of length scales involved, we develop a hierarchical computational scheme that includes models at both the cable and strand levels. At the Rutherford cable level, where the strands are treated as a homogeneous medium, a three-dimensional computational model is developed to determine the deformed shape of the cable that can subsequently be used to determine the strain state under specified loading conditions, which may be of thermal, magnetic, and mechanical origins. The results can then be transferred to the model at the strand/macro-filament level for rod restack process (RRP) strands, where the geometric details of the strand are included. This hierarchical scheme can be used to estimate the three-dimensional strain state in the conductor as well as to determine the effective properties of the strands and cables from the properties of individual components. Examples of the modeling results obtained for the orthotropic mechanical properties of the Rutherford cables are presented.
12. Cable deformation simulation and a hierarchical framework for Nb3Sn Rutherford cables
Arbelaez, D.; Prestemon, S. O.; Ferracin, P.; Godeke, A.; Dietderich, D. R.; Sabbi, G.
2009-09-13
Knowledge of the three-dimensional strain state induced in the superconducting filaments due to loads on Rutherford cables is essential to analyze the performance of Nb{sub 3}Sn magnets. Due to the large range of length scales involved, we develop a hierarchical computational scheme that includes models at both the cable and strand levels. At the Rutherford cable level, where the strands are treated as a homogeneous medium, a three-dimensional computational model is developed to determine the deformed shape of the cable that can subsequently be used to determine the strain state under specified loading conditions, which may be of thermal, magnetic, and mechanical origins. The results can then be transferred to the model at the strand/macro-filament level for rod restack process (RRP) strands, where the geometric details of the strand are included. This hierarchical scheme can be used to estimate the three-dimensional strain state in the conductor as well as to determine the effective properties of the strands and cables from the properties of individual components. Examples of the modeling results obtained for the orthotropic mechanical properties of the Rutherford cables are presented.
13. A unique cabling designed to produce Rutherford-type superconducting cable for the SSC project
Up to 25,000 Km of keystoned flat cable must be produced for the SSC project. Starting from a specification developed by Lawrence Berkeley Laboratory (LBL), a special cabling machine has been designed by Dour Metal. It has been designed to be able to run at a speed corresponding to a maximum production rate of 10 m/min. This cabling machine is the key part of the production line which consists of a precision Turkshead equipped with a variable power drive, a caterpillar, a dimensional control bench, a data acquisition system, and a take-up unit. The main features of the cabling unit to be described are a design with nearly equal path length between spool and assembling point for all the wires, and the possibility to run the machine with several over- or under-twisting ratios between cable and wires. These requirements led Dour Metal to the choice of an unconventional mechanical concept for a cabling machine. 4 refs., 2 figs
14. Distribution of AC loss in a HTS magnet for SMES with different operating conditions
Xu, Y.; Tang, Y.; Ren, L.; Jiao, F.; Song, M.; Cao, K.; Wang, D.; Wang, L.; Dong, H.
2013-11-01
The AC loss induced in superconducting tape may affect the performance of a superconducting device applied to power system, such as transformer, cable, motor and even Superconducting Magnetic Energy Storage (SMES). The operating condition of SMES is changeable due to the need of compensation to the active or reactive power according to the demand of a power grid. In this paper, it is investigated that the distribution of AC loss for a storage magnet on different operating conditions, which is based on finite element method (FEM) and measured properties of BSCCO/Ag tapes. This analytical method can be used to optimize the SMES magnet.
15. 2nd International Conference on Cable-Driven Parallel Robots
Bruckmann, Tobias
2015-01-01
This volume presents the outcome of the second forum to cable-driven parallel robots, bringing the cable robot community together. It shows the new ideas of the active researchers developing cable-driven robots. The book presents the state of the art, including both summarizing contributions as well as latest research and future options. The book cover all topics which are essential for cable-driven robots: Classification Kinematics, Workspace and Singularity Analysis Statics and Dynamics Cable Modeling Control and Calibration Design Methodology Hardware Development Experimental Evaluation Prototypes, Application Reports and new Application concepts
16. Underground spaces/cybernetic spaces
Tomaž Novljan
2000-01-01
Full Text Available A modern city space is a space where in the vertical and horizontal direction dynamic, non-linear processes exist, similar as in nature. Alongside the “common” city surface, cities have underground spaces as well that are increasingly affecting the functioning of the former. It is the space of material and cybernetic communication/transport. The psychophysical specifics of using underground places have an important role in their conceptualisation. The most evident facts being their limited volume and often limited connections to the surface and increased level of potential dangers of all kinds. An efficient mode for alleviating the effects of these specific features are artistic interventions, such as: shape, colour, lighting, all applications of the basic principles of fractal theory.
17. ac bidirectional motor controller
Schreiner, K.
1988-01-01
Test data are presented and the design of a high-efficiency motor/generator controller at NASA-Lewis for use with the Space Station power system testbed is described. The bidirectional motor driver is a 20 kHz to variable frequency three-phase ac converter that operates from the high-frequency ac bus being designed for the Space Station. A zero-voltage-switching pulse-density-modulation technique is used in the converter to shape the low-frequency output waveform.
18. Underground leaching of uranium ores
Large amounts of low-grade U ore, not worth processing by conventional methods, are to be found at many sites in mine pillars, walls, and backfilling. Many proven deposits are not being mined because the geological conditions are difficult or the U ore is of relatively low grade. Factors such as radioactive emission, radon emanation, and the formation of radioactive dust give rise to health hazards. When U ores are treated above ground, enormous quantities of solid and liquid radioactive waste and mining spoil accumulate. The underground leaching of U is a fundamentally different kind of process. It is based on the selective dissolving of U at the place where it occurs by a chemical reagent; all that reaches the ground surface is a solution containing U, and after extraction of the U by sorption the reagent is used again. The main difficult and dangerous operations associated with conventional methods (excavation; extraction and crushing of the ore; storage of wastes) are avoided. Before underground leaching the ore formation has to be fractured and large ore bodies broken down into blocks by shrinkage stopping. These operations are carried out by advanced machinery and require the presence underground of only a few workers. If the ore is in seams, the only mining operation is the drilling of boreholes. The chemical reagent is introduced under pressure through one set of boreholes, while the U bearing solution is pumped out from another set. The process is monitored with the help of control boreholes. After extraction of the U by sorption, the reagent is ready to be used again. Very few operations are involved and insignificant amounts of dissolved U escape into the surrounding rock formations. Experience has shown that underground leaching reduces the final cost of the U metal, increases productivity, reduces capital expenditure, and radically improves working conditions
19. Double wall underground storage tank
Canaan, E.B. Jr.; Wiegand, J.R.; Bartlow, D.H.
1993-07-06
A double wall underground storage tank is described comprising: (a) a cylindrical inner wall, (b) a cylindrical outer wall comprising plastic resin and reinforcement fibers, and (c) a layer of spacer filaments wound around the inner wall, the spacer filaments separating the inner and outer walls, and the spacer filaments being at least partially surrounded by voids to enable liquids to flow along the filaments.
20. Underground storage of carbon dioxide
Tanaka, Shoichi [Univ. of Tokyo, Hongo, Bunkyo-ku (Japan)
1993-12-31
Desk studies on underground storage of CO{sub 2} were carried out from 1990 to 1991 fiscal years by two organizations under contract with New Energy and Indestrial Technology Development Organization (NEDO). One group put emphasis on application of CO{sub 2} EOR (enhanced oil recovery), and the other covered various aspects of underground storage system. CO{sub 2} EOR is a popular EOR method in U.S. and some oil countries. At present, CO{sub 2} is supplied from natural CO{sub 2} reservoirs. Possible use of CO{sub 2} derived from fixed sources of industries is a main target of the study in order to increase oil recovery and storage CO{sub 2} under ground. The feasibility study of the total system estimates capacity of storage of CO{sub 2} as around 60 Gton CO{sub 2}, if worldwide application are realized. There exist huge volumes of underground aquifers which are not utilized usually because of high salinity. The deep aquifers can contain large amount of CO{sub 2} in form of compressed state, liquefied state or solution to aquifer. A preliminary technical and economical survey on the system suggests favorable results of 320 Gton CO{sub 2} potential. Technical problems are discussed through these studies, and economical aspects are also evaluated.
1. The stress and underground environment
Chama, A.
2009-04-01
Currently,the program of prevention in occupational health needs mainly to identify occupational hazards and strategy of their prevention.Among these risks,the stress represents an important psycho-social hazard in mental health,which unfortunately does not spare no occupation.My Paper attempts to highlight and to develop this hazard in its different aspects even its regulatory side in underground environment as occupational environment.In the interest of better prevention ,we consider "the information" about the impact of stress as the second prevention efficient and no expensive to speleologists,hygienists and workers in the underground areas. In this occasion of this event in Vienna,we also highlight the scientific works on the stress of the famous viennese physician and endocrinologist Doctor Hans Selye (1907-1982),nicknamed "the father of stress" and note on relation between biological rhythms in this underground area and psychological troubles (temporal isolation) (Jurgen Aschoff’s works and experiences out-of time).
2. First ATLAS Events Recorded Underground
Teuscher, R
As reported in the CERN Bulletin, Issue No.30-31, 25 July 2005 The ATLAS barrel Tile calorimeter has recorded its first events underground using a cosmic ray trigger, as part of the detector commissioning programme. This is not a simulation! A cosmic ray muon recorded by the barrel Tile calorimeter of ATLAS on 21 June 2005 at 18:30. The calorimeter has three layers and a pointing geometry. The light trapezoids represent the energy deposited in the tiles of the calorimeter depicted as a thick disk. On the evening of June 21, the ATLAS detector, now being installed in the underground experimental hall UX15, reached an important psychological milestone: the barrel Tile calorimeter recorded the first cosmic ray events in the underground cavern. An estimated million cosmic muons enter the ATLAS cavern every 3 minutes, and the ATLAS team decided to make good use of some of them for the commissioning of the detector. Although only 8 of the 128 calorimeter slices ('superdrawers') were included in the trigg...
3. Analytical Solution for the Current Distribution in Multistrand Superconducting Cables
Bottura, L; Fabbri, M G
2002-01-01
Current distribution in multistrand superconducting cables can be a major concern for stability in superconducting magnets and for field quality in particle accelerator magnets. In this paper we describe multistrand superconducting cables by means of a distributed parameters circuit model. We derive a system of partial differential equations governing current distribution in the cable and we give the analytical solution of the general system. We then specialize the general solution to the particular case of uniform cable properties. In the particular case of a two-strand cable, we show that the analytical solution presented here is identical to the one already available in the literature. For a cable made of N equal strands we give a closed form solution that to our knowledge was never presented before. We finally validate the analytical solution by comparison to numerical results in the case of a step-like spatial distribution of the magnetic field over a short Rutherford cable, both in transient and steady ...
4. Deployment/Retrieval Modeling of Cable-Driven Parallel Robot
Q. J. Duan
2010-01-01
Full Text Available A steady-state dynamic model of a cable in air is put forward by using some tensor relations. For the dynamic motion of a long-span Cable-Driven Parallel Robot (CDPR system, a driven cable deployment and retrieval mathematical model of CDPR is developed by employing lumped mass method. The effects of cable mass are taken into account. The boundary condition of cable and initial values of equations is founded. The partial differential governing equation of each cable is thus transformed into a set of ordinary differential equations, which can be solved by adaptive Runge-Kutta algorithm. Simulation examples verify the effectiveness of the driven cable deployment and retrieval mathematical model of CDPR.
5. RESPONSE CHARACTERISTICS OF WIND EXCITED CABLES WITH ARTIFICIAL RIVULET
顾明; 刘慈军; 徐幼麟; 项海帆
2002-01-01
A wind tunnel investigation of response characteristics of cables with artificial rivulet is presented.A series of cable section models of different mass and stiffness and damping ratio were designed with artificial rivulet.They were tested in smooth flow under different wind speed and yaw angle and for different position of artificial rivulet.The measured response of cable models was then analyzed and compared with the experimental results obtained by other researchers and the existing theories for wind-induced cable vibration.The results show that the measured response of horizontal cable models with artificial rivulet could be well predicted by Den Hartog' s galloping theory when wind is normal to the cable axis.For the wind with certain yaw angles, the cable models with artificial rivulet exhibit velocity-restricted response characteristics.
6. Design, manufacture, test and delivery of a 230 kV extruded irradiated crosslinked polyethylene cable. Final report
None
1978-01-01
A project was initiated to develop a 230 kV solid dielectric cable for use in underground transmission. The dielectric is to be polyethylene, crosslinked by electron bombardment. Compared to the more conventional chemically crosslinked polyethylene, the irradiated cable is expected to contain less sensitive defects and thus be more suitable for a 230 kV rating. A toroidally shaped diode was developed to provide a uniform radiation dose to a thick-walled coaxial cable. The diode is to receive an output wave form obtained by ringing a Marx generator into a peaking capacitor. Initial evaluation of the toroidal diode was performed on thin plaques and tapes of insulating and semi-conducting polyethylene polymers. Additionally, some miscellaneous ethylene plastics were briefly investigated. Using a 4.8 MV Van de Graaff pulse generator in conjunction with several diode configurations, 15 to 35 kV extruded HMW-PE cables were irradiated. Dose rate, temperature, and pressure effects were evaluated. It was found that with limited dose rate it was possible to produce excellent crosslink density and uniformity at room temperature and atmospheric pressure. A subsequent 60 Hz voltage endurance test on an irradiated cable sample indicated it had long term, high stress capability. An engineering study conducted to determine an acceptable irradiator system design is reported. It was estimated that a 7 MV peak voltage at a rate of 2 to 3 pulse/sec can be provided by a Marx generator/peaking capacitor and should be capable of crosslinking a polyethylene wall thickness of approximately 2.5 cm. Based on the accumulated test results and on the performance of the 7 MV irradiator predicted, it appears feasible to continue the work effort into the next scheduled phase.
7. AC/RF Superconductivity
Ciovati, Gianluigi [JLAB
2015-02-01
This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.
8. AC/RF Superconductivity
Ciovati, G.
2015-01-01
This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.
9. A Study on the System and Method for Drawing 3-Dimensional Cable Object with the cable tracking Navigation
3D cable tracking system with navigation makes it possible to easily search the objects which users want to retrieve and to measure the visual, spatial and structural distance by connecting the existing cable management system with 3D cable tracking system with navigation. With this consideration, we hope to create a more advanced cable management system in the future. I would like to describes the management system and method of the cable installed in the nuclear power plant, and how to build the database of the system. More specifically, it will be operated to the maintenance and management function, and the life management system of the cable, describing the creation method of three-dimensional cable object formed by the information of trace route through navigation and how to build the system database automatically
10. A Study on the System and Method for Drawing 3-Dimensional Cable Object with the cable tracking Navigation
Bhang, Keugjin; Jung, Sunchul [Central Research Institute, Daejeon (Korea, Republic of); Hong, Junhee [Chungnam Univ., Daejeon (Korea, Republic of)
2013-05-15
3D cable tracking system with navigation makes it possible to easily search the objects which users want to retrieve and to measure the visual, spatial and structural distance by connecting the existing cable management system with 3D cable tracking system with navigation. With this consideration, we hope to create a more advanced cable management system in the future. I would like to describes the management system and method of the cable installed in the nuclear power plant, and how to build the database of the system. More specifically, it will be operated to the maintenance and management function, and the life management system of the cable, describing the creation method of three-dimensional cable object formed by the information of trace route through navigation and how to build the system database automatically.
11. Offshore wind farm electrical cable layout optimization
Pillai, A. C.; Chick, J.; Johanning, L.; Khorasanchi, M.; de Laleu, V.
2015-12-01
This article explores an automated approach for the efficient placement of substations and the design of an inter-array electrical collection network for an offshore wind farm through the minimization of the cost. To accomplish this, the problem is represented as a number of sub-problems that are solved in series using a combination of heuristic algorithms. The overall problem is first solved by clustering the turbines to generate valid substation positions. From this, a navigational mesh pathfinding algorithm based on Delaunay triangulation is applied to identify valid cable paths, which are then used in a mixed-integer linear programming problem to solve for a constrained capacitated minimum spanning tree considering all realistic constraints. The final tree that is produced represents the solution to the inter-array cable problem. This method is applied to a planned wind farm to illustrate the suitability of the approach and the resulting layout that is generated.
12. Development of polymer packaging for power cable
S. Sremac
2014-10-01
Full Text Available This paper discusses the issues of product design and the procedure of developing polymer packaging as one of the most important engineering tasks. For the purpose of packing power cables a polymer packaging has been designed in the form of drum. Packaging and many other consumer products are largely produced using polymeric materials due to many positive features. High Density Polyethylene is the type of polyethylene proposed for packaging purposes due to its low degree of branching and strong intermolecular forces. Transport and storage processes were automated based on the radio-frequency identification technology. The proposed system is flexible in terms of its possibility of accepting and processing different types of cables and other products.
13. Aging assessment of cable for NPP
Activation energy is measured with UTM (Universal Testing Machine), TGA (Thermo-gravimetric Analyzer) and DMA (Dynamic Mechanical Analyzer) to analyze the aging degree of cables for NPP (Nuclear Power Plant). Insulation power cables containing EPR (Ethylene Propylene Rubber) are arranged for two kinds of specimens which are intact specimens and aged specimens by exposing to LOCA (Loss of Coolant Accident) environmental conditions regulated in IEEE 323. In case of intact specimen, values of activation energy are 1.1 eV for UTM, 1.24 eV with storage modulus and 1.13 eV with loss modulus for DMA, 1.29 eV for TGA, respectively. Damping of specimen under LOCA conditions decreases the activation energy to 0.88 eV for TGA. (author)
14. Horizon-T Experiment Calibrations - Cables
Beznosko, D; Iakovlev, A; Makhataeva, Z; Vildanova, M I; Yelshibekov, K; Zhukov, V V
2016-01-01
An innovative detector system called Horizon-T is constructed to study Extensive Air Showers (EAS) in the energy range above 1016 eV coming from a wide range of zenith angles (0o - 85o). The system is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. The detector consists of eight charged particle detection points separated by the distance up to one kilometer as well as optical detector to view the Vavilov-\\v{C}erenkov light from the EAS. Each detector connects to the Data Acquisition system via cables. The calibration of the time delay for each cable and the signal attenuation is provided in this article.
15. Underground siting is a nuclear option
Underground siting of nuclear power plants is a concept that can be both technologically feasible and economically attractive. To meet both these criteria, however, each underground nuclear plant must be adapted to take full advantage of its location. It cannot be a unit that was designed for the surface and is then buried. Seeking to develop potential commercial programs, Underground Design Consultants (UDC)--a joint venture of Parsons, Brinckerhoff, Quade and Douglas, New York City, Vattenbyggnadsbyran (VBB), Stockholm, Sweden, and Foundation Sciences, Inc., Portland, Oregon--has been studying the siting of nuclear plants underground. UDC has made a presentation to EPRI on the potential for underground siting in the U.S. The summary presented here is based on the experiences of underground nuclear power plants in Halden, Norway; Agesta, Sweden; Chooz, France; and Lucens, Switzerland. Data from another plant in the design phase in Sweden and UDC's own considered judgment were also used
16. Influence of strand surface condition on interstrand contact resistance and coupling loss in NbTi-wound Rutherford cables
Sumption, M D; Scanlan, R M; Nijhuis, A; ten Kate, H H J; Kim, S W; Wake, M; Shintomi, T
1999-01-01
Presented in this work are the results of directly measured and AC- loss-derived interstrand contact resistance (ICR) measurements performed magnetically or resistively on bare-Cu and coated-strand pairs, calorimetrically on $9 11-strand Rutherford cables wound with strands that had been coated with various metallic and insulating layers, and calorimetrically and magnetically on 28-strand Rutherford cables (LHC-type) wound with bare-Cu-, Ni-, and $9 stabrite-plated strands. Comparisons are made of the effects of various conditions of heat treatment, HT (time and temperature), and pressure (applied during HT and then either maintained or re-applied during measurement). The $9 resulting ICRs are compared and interpreted in terms of the oxide layer on the strand coating and its response to curing conditions. (66 refs).
17. Development of radiation resistant electrical cable insulations
Two new polyethylene cable insulations have been formulated for nuclear applications, and have been tested under gamma radiation. Both insulations are based on low density polyethylene, one with PbO and the other with Sb2O3 as additives. The test results show that the concept of using inorganic antioxidants to retard radiation initiated oxidation (RIO) is viable. PbO is more effective than Sb2O3 in minimizing RIO
18. Optical fibre cable selection for electricity utilities
NONE
2001-07-01
The report provides an assessment of the range of optical fibre cable solutions available, by type e.g. OPGW, ADSS, rather than by design. it also examines the key issues which will influence an electricity utilities decisions and proposes a method of evaluating the options to identify the one which most closely matches the utility's critical needs, with measurements against time, cost and quality targets. (author)
19. Ultrasonic security seal with a cable
The sonic delay line of the seal is prolongated by a truncated part and terminated by a spherical cap which can be marked. The sealing capsule has a bore adapted to the size of the truncated part of the identity module. The sealing cable is fastened between the sealing capsule and the module. Application is made to the monitoring of containers for dangerous or radioactive materials
20. Space charge fields in DC cables
McAllister, Iain Wilson; Crichton, George C; Pedersen, Aage
The space charge that accumulates in DC cables can, mathematically, be resolved into two components. One is related to the temperature and the other to the magnitude of the electric field strength. Analytical expressions for the electric fields arising from each of these space charge components are...... derived. Thereafter, the significance of these field components under both normal operating conditions and immediately following polarity reversal is discussed...
1. Influence of Icing on Bridge Cable Aerodynamics
Koss, Holger; Frej Henningsen, Jesper; Olsen, Idar
2013-01-01
determination of these force coefficients require a proper simulation of the ice layer occurring under the specific climatic conditions, favouring real ice accretion over simplified artificial reproduction. The work presented in this paper was performed to study the influence of ice accretion on the aerodynamic...... forces of different bridge cables types. The experiments were conducted in a wind tunnel facility capable amongst others to simulate incloud icing conditions....
2. Automated wireless monitoring system for cable tension using smart sensors
Sim, Sung-Han; Li, Jian; Jo, Hongki; Park, Jongwoong; Cho, Soojin; Spencer, Billie F.; Yun, Chung-Bang
2013-04-01
Cables are critical load carrying members of cable-stayed bridges; monitoring tension forces of the cables provides valuable information for SHM of the cable-stayed bridges. Monitoring systems for the cable tension can be efficiently realized using wireless smart sensors in conjunction with vibration-based cable tension estimation approaches. This study develops an automated cable tension monitoring system using MEMSIC's Imote2 smart sensors. An embedded data processing strategy is implemented on the Imote2-based wireless sensor network to calculate cable tensions using a vibration-based method, significantly reducing the wireless data transmission and associated power consumption. The autonomous operation of the monitoring system is achieved by AutoMonitor, a high-level coordinator application provided by the Illinois SHM Project Services Toolsuite. The monitoring system also features power harvesting enabled by solar panels attached to each sensor node and AutoMonitor for charging control. The proposed wireless system has been deployed on the Jindo Bridge, a cable-stayed bridge located in South Korea. Tension forces are autonomously monitored for 12 cables in the east, land side of the bridge, proving the validity and potential of the presented tension monitoring system for real-world applications.
3. Causes and consequences of underground economy
Mara, Eugenia-Ramona
2011-01-01
In this endeavor an attempt has been made to investigate the major causes and factors of influence of the underground economy. Our analysis is based on the study of tax payer behavior and taxation system pattern. The paper examines how social institutions and government policies affect underground economy. All these factors have an important impact on the level and size of underground economy and determine the consequences of this phenomenon.
4. UNDERGROUND ECONOMY, GDP AND STOCK MARKET
Caus Vasile Aurel
2012-01-01
Economic growth is affected by the size and dynamics of underground economy. Determining this size is a subject of research for many authors. In this paper we present the relationship between underground economy dynamics and the dynamics of stock markets. The observations are based on regression used by Tanzi (1983) and the relationship between GDP and stock market presented in Tudor (2008). The conclusion of this paper is that the dynamics of underground economy is influenced by dynamic of f...
5. Transport Model of Underground Sediment in Soils
Sun Jichao; Wang Guangqian
2013-01-01
Studies about sediment erosion were mainly concentrated on the river channel sediment, the terrestrial sediment, and the underground sediment. The transport process of underground sediment is studied in the paper. The concept of the flush potential sediment is founded. The transport equation with stable saturated seepage is set up, and the relations between the flush potential sediment and water sediment are discussed. Flushing of underground sediment begins with small particles, and large pa...
6. Prospective barrier coatings for superconducting cables
Ipatov, Y.; Dolgosheev, P.; Sytnikov, V.
1997-07-01
Known and prospective types of chromium coatings, used in the production of superconducting `cable-in-conduit' conductors designed for the ITER and other projects, are considered. The influence of the technological conditions during the galvanic plating of hard, grey, black and combined chromium coatings in various electrolytes and the annealing conditions in air and in vacuum on the contact electrical resistance of copper and superconducting wire at room temperature and 4.2 K as well as on other physical properties, e.g. resistance to abrasion, elasticity and thickness of the coatings, is investigated. Black oxide - chromium coatings and combined chromium coatings, containing oxides of chromium and a number of other metals, ensure the possibility of a significant increase of contact resistance as well as its regulation in a broad range of values in comparison with hard chromium. The results of the present work and also an independent investigation of the cable containing the strand, manufactured in JSC `VNIIKP', allow us to propose the oxide - chromium coating as a barrier layer for multistrand superconducting cables.
7. Cable energy function of cortical axons.
Ju, Huiwen; Hines, Michael L; Yu, Yuguo
2016-01-01
Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na(+)-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na(+)-counting method severely underestimates energy cost in the cable model by 20-70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954
8. Cable energy function of cortical axons
Ju, Huiwen; Hines, Michael L.; Yu, Yuguo
2016-01-01
Accurate estimation of action potential (AP)-related metabolic cost is essential for understanding energetic constraints on brain connections and signaling processes. Most previous energy estimates of the AP were obtained using the Na+-counting method, which seriously limits accurate assessment of metabolic cost of ionic currents that underlie AP conduction along the axon. Here, we first derive a full cable energy function for cortical axons based on classic Hodgkin-Huxley (HH) neuronal equations and then apply the cable energy function to precisely estimate the energy consumption of AP conduction along axons with different geometric shapes. Our analytical approach predicts an inhomogeneous distribution of metabolic cost along an axon with either uniformly or nonuniformly distributed ion channels. The results show that the Na+-counting method severely underestimates energy cost in the cable model by 20–70%. AP propagation along axons that differ in length may require over 15% more energy per unit of axon area than that required by a point model. However, actual energy cost can vary greatly depending on axonal branching complexity, ion channel density distributions, and AP conduction states. We also infer that the metabolic rate (i.e. energy consumption rate) of cortical axonal branches as a function of spatial volume exhibits a 3/4 power law relationship. PMID:27439954
9. The ANDES Deep Underground Laboratory
Bertou, X
2013-01-01
ANDES (Agua Negra Deep Experiment Site) is a unique opportunity to build a deep underground laboratory in the southern hemisphere. It will be built in the Agua Negra tunnel planned between Argentina and Chile, and operated by the CLES, a Latin American consortium. With 1750m of rock overburden, and no close- by nuclear power plant, it will provide an extremely radiation quiet environment for neutrino and dark matter experiments. In particular, its location in the southern hemisphere should play a major role in understanding dark matter modulation signals.
10. Third symposium on underground mining
None
1977-01-01
The Third Symposium on Underground Mining was held at the Kentucky Fair and Exposition Center, Louisville, KY, October 18--20, 1977. Thirty-one papers have been entered individually into EDB and ERA. The topics covered include mining system (longwall, shortwall, room and pillar, etc.), mining equipment (continuous miners, longwall equipment, supports, roof bolters, shaft excavation equipment, monitoring and control systems. Maintenance and rebuilding facilities, lighting systems, etc.), ventilation, noise abatement, economics, accidents (cost), dust control and on-line computer systems. (LTN)
11. Underground Shocks Ground Zero Responses
Maurizio Bovi
2004-01-01
The aim of this paper is twofold. First, new annual data on Italian irregular sector for the period 1980-1991 are reconstructed. These data are compatible with the available 1992-2001 official data. Second, based on this self-consistent “long” sample a time series analysis of the two sides – the underground and the regular - of the Italian GDP is performed. Results from univariate and VAR models seem to suggest that there are no connections (causal relationship, feedbacks, contemporaneous cyc...
12. Increased Ac excision (iae): Arabidopsis thaliana mutations affecting Ac transposition
The maize transposable element Ac is highly active in the heterologous hosts tobacco and tomato, but shows very much reduced levels of activity in Arabidopsis. A mutagenesis experiment was undertaken with the aim of identifying Arabidopsis host factors responsible for the observed low levels of Ac activity. Seed from a line carrying a single copy of the Ac element inserted into the streptomycin phosphotransferase (SPT) reporter fusion, and which displayed typically low levels of Ac activity, were mutagenized using gamma rays. Nineteen mutants displaying high levels of somatic Ac activity, as judged by their highly variegated phenotypes, were isolated after screening the M2 generation on streptomycin-containing medium. The mutations fall into two complementation groups, iae1 and iae2, are unlinked to the SPT::Ac locus and segregate in a Mendelian fashion. The iae1 mutation is recessive and the iae2 mutation is semi-dominant. The iae1 and iae2 mutants show 550- and 70-fold increases, respectively, in the average number of Ac excision sectors per cotyledon. The IAE1 locus maps to chromosome 2, whereas the SPT::Ac reporter maps to chromosome 3. A molecular study of Ac activity in the iae1 mutant confirmed the very high levels of Ac excision predicted using the phenotypic assay, but revealed only low levels of Ac re-insertion. Analyses of germinal transposition in the iae1 mutant demonstrated an average germinal excision frequency of 3% and a frequency of independent Ac re-insertions following germinal excision of 22%. The iae mutants represents a possible means of improving the efficiency of Ac/Ds transposon tagging systems in Arabidopsis, and will enable the dissection of host involvement in Ac transposition and the mechanisms employed for controlling transposable element activity
13. 30 CFR 57.8519 - Underground main fan controls.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground main fan controls. 57.8519 Section... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Ventilation Surface and Underground § 57.8519 Underground main fan controls. All underground main fans...
14. Rapid optimization of tension distribution for cable-driven parallel manipulators with redundant cables
Ouyang, Bo; Shang, Weiwei
2016-03-01
The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method. The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method.
15. Hermetisk AC-Krets
Hirsch, Carl; Smirnoff, Alexander
2007-01-01
Under sex månader våren 2007 har ett samarbete mellan Volvo Lastvagnar och två studenter från KTH, inriktning Integrerad produktutveckling vid institutionen för maskinkonstruktion, pågått i form av ett examensarbete på 20 poäng. Dagens AC-system i Volvos lastbilar avger 20-40 g/år av köldmediet R134a som är en kraftfull växthusgas. Detta sker främst genom diffusion via slangar och tätningsmaterial. Syftet med detta examensarbete är att ta fram förslag på tekniska lösningar på ett nytt AC-syst...
16. Numerical method of thermal design of power cables
Bryukhanov, O.N.; Trigorlyy, S.V.
1985-05-01
Increasing the accuracy of computation of permissible current loads in cables requires that thermal calculations be performed considering the actual distribution of temperatures in the cables. An analysis of methods of thermal design of cables showed that numerical methods allowing most complete consideration of various heat exchange factors are superior. The authors suggest the use of the method of finite elements to study thermal states of multiple-conductor power cables laid in various ways. As an example, thermal calculation of three-conductor cable with circular conductors is studied. For a number of cables the permissible current loads calculated by the method of finite elements are greater than those established by the standards documents of calculated according to previous methods.
17. Aging assessment of electrical cables from NPD nuclear generating station
Degradation of NPD Nuclear Generating Station control and power cables after approximately 25 years of service was assessed. The PVC and SBR insulated cables were also exposed to radiation, accident and post-accident conditions, and accelerated aging to simulate extended service life. The degradation of the samples from the containment boiler room was minimal, caused mainly by thermal conditions rather than radiation. Although irradiation to 55 Mrad, simulating normal operation and accident radiation levels, caused degradation, the cables could still function during accident and post-accident conditions. Accelerated thermal aging to simulate an additional 10 years of service at 45 degrees C caused embrittlement of the PVC and a 60% decrease in elongation of the SBR. Comparison of test results of aged NPD cables with newer PVC cables obtained from Pickering NGS 'A' shows that the newer cables have improved aging stability and therefore should provide adequate service during their design life of 31 years
18. Optimization and stability of a cable-in-conduit superconductor
The optimization process for strand number and diameter, cable void fraction, and Cu/NbTi-ratio of the cable-in-conduit conductor for the superconducting magnet system of the planned stellarator fusion experiment Wendelstein 7-X is presented. Main optimization criteria are stability and cable cooling requirements, taking into account transient disturbances and losses. A simple stability criterion regarding transient disturbances is used which is derived from cable compression experiments. The resulting data for the 16 kA, 6 T cable are: cable and strand diameter ∼11.5 mm and ∼0.57 mm, respectively, strand number ∼250, void ∼36%, and Cu/sc-ratio ∼2.7
19. Dynamic behavior of stay cables with passive negative stiffness dampers
Shi, Xiang; Zhu, Songye; Li, Jin-Yang; Spencer, Billie F., Jr.
2016-07-01
This paper systematically investigates the dynamic behavior of stay cables with passive negative stiffness dampers (NSD) installed close to the cable end. A passive NSD is modeled as a combination of a negative stiffness spring and a viscous damper. Through both analytical and numerical approaches, parametric analysis of negative stiffness and viscous damping are conducted to systematically evaluate the vibration control performance of passive NSD on stay cables. Since negative stiffness is an unstable element, the boundary of passive negative stiffness for stay cables to maintain stability is also derived. Results reveal that the asymptotic approach is only applicable to passive dampers with positive or moderate negative stiffness, and loses its accuracy when a passive NSD possesses significant negative stiffness. It has been found that the performance of passive NSD can be much better than those of conventional viscous dampers. The superior control performance of passive NSD in cable vibration mitigation is validated through numerical simulations of a full-scale stay cable.
20. Analytical dynamic solution of a flexible cable-suspended manipulator
Bamdad, Mahdi
2013-12-01
Cable-suspended manipulators are used in large scale applications with, heavy in weight and long in span cables. It seems impractical to maintain cable assumptions of smaller robots for large scale manipulators. The interactions among the cables, platforms and actuators can fully evaluate the coupled dynamic analysis. The structural flexibility of the cables becomes more pronounced in large manipulators. In this paper, an analytic solution is provided to solve cable vibration. Also, a closed form solution can be adopted to improve the dynamic response to flexibility. The output is provided by the optimal torque generation subject to the actuator limitations in a mechatronic sense. Finally, the performance of the proposed algorithm is examined through simulations.
1. Antenna mechanism of length control of actin cables
Mohapatra, Lishibanya; Kondev, Jane
2014-01-01
Actin cables are linear cytoskeletal structures that serve as tracks for myosin-based intracellular transport of vesicles and organelles in both yeast and mammalian cells. In a yeast cell undergoing budding, cables are in constant dynamic turnover yet some cables grow from the bud neck toward the back of the mother cell until their length roughly equals the diameter of the mother cell. This raises the question: how is the length of these cables controlled? Here we describe a novel molecular mechanism for cable length control inspired by recent experimental observations in cells. This antenna mechanism involves three key proteins: formins, which polymerize actin, Smy1 proteins, which bind formins and inhibit actin polymerization, and myosin motors, which deliver Smy1 to formins, leading to a length-dependent actin polymerization rate. We compute the probability distribution of cable lengths as a function of several experimentally tuneable parameters such as the formin-binding affinity of Smy1 and the concentra...
2. Transverse stress effects in Nb3Sn cables
The effect of transverse compressive stress on the critical current of solder-filled and unfilled Nb3Sn cables is reported. The conductor used in this study is a Nb3Sn Rutherford cable manufactured with a bronze-process wire of 0.92 mm diameter. Like epoxy-impregnated cables, solder-filled cables exhibit much less degradation than wire samples when subjected to the same stresses. On the other hand, unfilled specimens are irreversibly damaged at the thin edge when loaded to 160 MPa, and show significantly higher degradation than similar specimens of the solder-filled cable. A finite-element calculation of the stress state inside a particular composite superconductor indicates that more compressive stress is developed in the virgin wire than in a straight wire segment in a real cable environment
3. Optical Fiber Grating Sensor for Force Measurement of Anchor Cable
JIANG Desheng; FU Jinghua; LIU Shengchun; SUI Lingfeng; FU Rong
2006-01-01
The development of the sensor suitable for measuring large load stress to the anchor cable becomes an important task in bridge construction and maintenance. Therefore, a new type of optical fiber sensor was developed in the laboratory - optical fiber grating sensor for force measurement of anchor cable (OFBFMAC). No similar report about this kind of sensor has been found up to now in China and other countries. This sensor is proved to be an effective way of monitoring in processes of anchor cable installation, cable cutting, cable force regulation, etc, with the accurate and repeatable measuring results. Its successful application in the tie bar cable force safety monitoring for Wuhan Qingchuan bridge is a new exploration of optical fiber grating sensing technology in bridge tie bar monitoring system.
4. The Coupling Effect of Spatial Reticulated Shell Structure with Cables
MA Jun; ZHOU Dai; FU Xu-chen
2005-01-01
The spatial reticulated shell structure with cables (RSC) is a kind of coupling working system, which consists of flexible cables, reticulated shell structure (RS) and tower columns. The dynamic analysis of RSC based on the coupling model was carried out. Three kinds of elements such as the spatial bar element, cable element and beam element were introduced to analyze the reticulated shell, cable and tower column respectively. Furthermore,such parameter influences as structural boundary conditions, grid configuration, the span-to-depth ratio and the arrangement of cable system upon structural dynamics were analyzed. The structural vibration modes can be divided into four groups based on some numerical examples. And the frequencies in the same group are very close while the frequencies in different groups are different from each other obviously. It is clear that the sequence of the appearance of the each mode group heavily depends on the comparative stiffness of the tower column system, RS and cables.
5. Study on the Configuration of Towed Flexible Cables
陈敏康; 张仁颐
2003-01-01
Based on the fundamental equation of flexible cable dynamics for a towed system, an easily solved mathematical model is set up in this paper by means of appropriate simplification. Several regular patterns of spatial motion of towed flexible cables in water are obtained through numerical simulation with the finite difference method, and then modification and verification by trial results at sea. A technical support is provided for the towing ship to maneuver properly when a flexible cable is towed. Furthermore, the relations between two towed flexible cables, which are towed simultaneously by a ship, are investigated. The results show that the ship towing two flexible cables is safe under the suggested arrangement of two winches for the towing system, and the coiling/uncoiling sequences of the cables as well as the suggested way of maneuvering.
6. Underground repository for radioactive wastes
In the feasibility study for an underground repository in Argentina, the conceptual basis for the final disposal of high activity nuclear waste was set, as well as the biosphere isolation, according to the multiple barrier concept or to the engineering barrier system. As design limit, the container shall act as an engineering barrier, granting the isolation of the radionuclides for approximately 1000 years. The container for reprocessed and vitrified wastes shall have three metallic layers: a stainless steel inner layer, an external one of a metal to be selected and a thick intermediate lead layer preselected due to its good radiological protection and corrosion resistance. Therefore, the study of the lead corrosion behaviour in simulated media of an underground repository becomes necessary. Relevant parameters of the repository system such as temperature, pressure, water flux, variation in salt concentrations and oxidants supply shall be considered. At the same time, a study is necessary on the galvanic effect of lead coupled with different candidate metals for external layer of the container in the same experimental conditions. Also temporal evaluation about the engineering barrier system efficiency is presented in this thesis. It was considered the extrapolated results of corrosion rates and literature data about the other engineering barriers. Taking into account that corrosion is of a generalized type, the integrity of the lead shall be maintained for more than 1000 years and according to temporal evaluation, the multiple barrier concept shall retard the radionuclide dispersion to the biosphere for a period of time between 104 and 106 years. (Author)
7. Underground storage tank management plan
The Underground Storage Tank (UST) Management Program at the Oak Ridge Y-12 Plant was established to locate UST systems in operation at the facility, to ensure that all operating UST systems are free of leaks, and to establish a program for the removal of unnecessary UST systems and upgrade of UST systems that continue to be needed. The program implements an integrated approach to the management of UST systems, with each system evaluated against the same requirements and regulations. A common approach is employed, in accordance with Tennessee Department of Environment and Conservation (TDEC) regulations and guidance, when corrective action is mandated. This Management Plan outlines the compliance issues that must be addressed by the UST Management Program, reviews the current UST inventory and compliance approach, and presents the status and planned activities associated with each UST system. The UST Management Plan provides guidance for implementing TDEC regulations and guidelines for petroleum UST systems. (There are no underground radioactive waste UST systems located at Y-12.) The plan is divided into four major sections: (1) regulatory requirements, (2) implementation requirements, (3) Y-12 Plant UST Program inventory sites, and (4) UST waste management practices. These sections describe in detail the applicable regulatory drivers, the UST sites addressed under the Management Program, and the procedures and guidance used for compliance with applicable regulations
8. Earthquake damage to underground facilities
The potential seismic risk for an underground nuclear waste repository will be one of the considerations in evaluating its ultimate location. However, the risk to subsurface facilities cannot be judged by applying intensity ratings derived from the surface effects of an earthquake. A literature review and analysis were performed to document the damage and non-damage due to earthquakes to underground facilities. Damage from earthquakes to tunnels, s, and wells and damage (rock bursts) from mining operations were investigated. Damage from documented nuclear events was also included in the study where applicable. There are very few data on damage in the subsurface due to earthquakes. This fact itself attests to the lessened effect of earthquakes in the subsurface because mines exist in areas where strong earthquakes have done extensive surface damage. More damage is reported in shallow tunnels near the surface than in deep mines. In mines and tunnels, large displacements occur primarily along pre-existing faults and fractures or at the surface entrance to these facilities.Data indicate vertical structures such as wells and shafts are less susceptible to damage than surface facilities. More analysis is required before seismic criteria can be formulated for the siting of a nuclear waste repository
9. Underground storage tank management plan
NONE
1994-09-01
The Underground Storage Tank (UST) Management Program at the Oak Ridge Y-12 Plant was established to locate UST systems in operation at the facility, to ensure that all operating UST systems are free of leaks, and to establish a program for the removal of unnecessary UST systems and upgrade of UST systems that continue to be needed. The program implements an integrated approach to the management of UST systems, with each system evaluated against the same requirements and regulations. A common approach is employed, in accordance with Tennessee Department of Environment and Conservation (TDEC) regulations and guidance, when corrective action is mandated. This Management Plan outlines the compliance issues that must be addressed by the UST Management Program, reviews the current UST inventory and compliance approach, and presents the status and planned activities associated with each UST system. The UST Management Plan provides guidance for implementing TDEC regulations and guidelines for petroleum UST systems. (There are no underground radioactive waste UST systems located at Y-12.) The plan is divided into four major sections: (1) regulatory requirements, (2) implementation requirements, (3) Y-12 Plant UST Program inventory sites, and (4) UST waste management practices. These sections describe in detail the applicable regulatory drivers, the UST sites addressed under the Management Program, and the procedures and guidance used for compliance with applicable regulations.
10. AC HTS Transmission Cable for Integration into the Future EHV Grid of the Netherlands
Zuijderduin, R.; Chevtchenko, O.; Smit, J.J.; Aanhaanen, G.; Melnik, I.; Geschiere, A.
2012-01-01
Due to increasing power demand, the electricity grid of the Netherlands is changing. The future grid must be capable to transmit all the connected power. Power generation will be more decentralized like for instance wind parks connected to the grid. Furthermore, future large scale production units a
11. DC Cable Short Circuit Fault Protection in VSC-MTDC
Lu, Shining
2015-01-01
With the development of offshore wind farms, Voltage Source Converter based High Voltage Direct Current or Multi-terminal High Voltage Direct Current Technology (VSC-HVDC/MTDC) is becoming promising in the field of large-capacity and long-distance power transmission. However, its extreme vulnerability to DC contingencies remains a challenge in both research and practice. DC cable short circuit faults, or cable pole-to-pole faults, though less common than DC cable ground faults, can cause the ...
12. 46 CFR 111.60-6 - Fiber optic cable.
2010-10-01
... 46 Shipping 4 2010-10-01 2010-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping... REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be... 60332-3-22 (all three standards incorporated by reference; see 46 CFR 110.10-1); or (b) Be installed...
13. Similarity Analysis of Cable Insulations by Chemical Test
As result of this experiment, it was found that FT-IR test for material composition, TGA test for aging trend are applicable for similarity analysis of cable materials. OIT is recommended as option if TGA doesn't show good trend. Qualification of new insulation by EQ report of old insulation should be based on higher activation energy of new insulation than that of old one in the consideration of conservatism. In old nuclear power plant, it is easy to find black cable which has no marking of cable information such as manufacturer, material name and voltage. If a type test is required for qualification of these cables, how could I select representative cable? How could I determine the similarity of these cables? If manufacturer has qualified a cable for nuclear power plant more than a decade ago and composition of cable material is changed with similar one, is it acceptable to use the old EQ report for recently manufactured cable? It is well known to use FT-IR method to determine the similarity of cable materials. Infrared ray is easy tool to compare compositions of each material. But, it is not proper to compare aging trend of these materials. Study for similarity analysis of cable insulation by chemical test is described herein. To study a similarity evaluation method for polymer materials, FT-IR, TGA and OIT tests were performed for two cable insulation(old and new) which were supplied from same manufacturer. FT-IR shows good result to compare material compositions while TGA and OIT show good result to compare aging character of materials
14. Total Magnetic Field Signatures over Submarine HVDC Power Cables
Johnson, R. M.; Tchernychev, M.; Johnston, J. M.; Tryggestad, J.
2013-12-01
Mikhail Tchernychev, Geometrics, Inc. Ross Johnson, Geometrics, Inc. Jeff Johnston, Geometrics, Inc. High Voltage Direct Current (HVDC) technology is widely used to transmit electrical power over considerable distances using submarine cables. The most commonly known examples are the HVDC cable between Italy and Greece (160 km), Victoria-Tasmania (300 km), New Jersey - Long Island (82 km) and the Transbay cable (Pittsburg, California - San-Francisco). These cables are inspected periodically and their location and burial depth verified. This inspection applies to live and idle cables; in particular a survey company could be required to locate pieces of a dead cable for subsequent removal from the sea floor. Most HVDC cables produce a constant magnetic field; therefore one of the possible survey tools would be Marine Total Field Magnetometer. We present mathematical expressions of the expected magnetic fields and compare them with fields observed during actual surveys. We also compare these anomalies fields with magnetic fields produced by other long objects, such as submarine pipelines The data processing techniques are discussed. There include the use of Analytic Signal and direct modeling of Total Magnetic Field. The Analytic Signal analysis can be adapted using ground truth where available, but the total field allows better discrimination of the cable parameters, in particular to distinguish between live and idle cable. Use of a Transverse Gradiometer (TVG) allows for easy discrimination between cable and pipe line objects. Considerable magnetic gradient is present in the case of a pipeline whereas there is less gradient for the DC power cable. Thus the TVG is used to validate assumptions made during the data interpretation process. Data obtained during the TVG surveys suggest that the magnetic field of a live HVDC cable is described by an expression for two infinite long wires carrying current in opposite directions.
15. A linear model of stationary elevator traveling and compensation cables
Zhu, W. D.; Ren, H.
2013-06-01
Based on a recent asymptotic analysis of a nonlinear model of a slack cable, a computationally efficient, linear model is developed for calculating the natural frequencies, mode shapes, and dynamic responses of stationary elevator traveling and compensation cables. The linear cable model consists of two vertical cable segments connected by a half-circular lower loop. The two vertical cable segments are modeled as a string with a variable tension due to the weight of the cable. The horizontal displacements of the cable segments consist of boundary-induced displacements and relative elastic displacements, where the boundary-induced displacements are interpolated from the displacements of the two lower ends of the cable segments, and the relative elastic displacements satisfy the corresponding homogeneous boundary conditions of the cable segments. The horizontal displacement of the lower loop is interpolated from those of the two lower ends of the two cable segments, and the bending stiffness of the lower loop is modeled by a spring with a constant stiffness, which can be calculated from the nonlinear model. Given a car position, the natural frequencies and mode shapes of an elevator traveling or compensation cable are calculated using the linear model and compared with those from the nonlinear model. The calculated natural frequencies are also compared with those from a full-scale experiment. In addition, the dynamic responses of a cable under a boundary excitation are calculated and compared with those from the nonlinear model. There is a good agreement between the predictions from the linear and nonlinear models and between the measured natural frequencies from the full-scale experiment and the corresponding calculated ones.
16. Similarity Analysis of Cable Insulations by Chemical Test
Kim, Jong Seog [Central Research Institute of Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)
2013-10-15
As result of this experiment, it was found that FT-IR test for material composition, TGA test for aging trend are applicable for similarity analysis of cable materials. OIT is recommended as option if TGA doesn't show good trend. Qualification of new insulation by EQ report of old insulation should be based on higher activation energy of new insulation than that of old one in the consideration of conservatism. In old nuclear power plant, it is easy to find black cable which has no marking of cable information such as manufacturer, material name and voltage. If a type test is required for qualification of these cables, how could I select representative cable? How could I determine the similarity of these cables? If manufacturer has qualified a cable for nuclear power plant more than a decade ago and composition of cable material is changed with similar one, is it acceptable to use the old EQ report for recently manufactured cable? It is well known to use FT-IR method to determine the similarity of cable materials. Infrared ray is easy tool to compare compositions of each material. But, it is not proper to compare aging trend of these materials. Study for similarity analysis of cable insulation by chemical test is described herein. To study a similarity evaluation method for polymer materials, FT-IR, TGA and OIT tests were performed for two cable insulation(old and new) which were supplied from same manufacturer. FT-IR shows good result to compare material compositions while TGA and OIT show good result to compare aging character of materials.
17. Prospects of Research on Cable Logging in Forest Engineering Community
Cavalli, Raffaele
2012-01-01
An analysis of researches on cable logging carried out in the past 12 years (2000–2011) as found in the scientific literature at international level is proposed in order to evaluate which have been the main topics of interest of the researchers and to evaluate the evolution of the research in the field of cable logging in the next future. International scientific literature on cable logging was extracted from the main databases, scientific journals and conference proceedings on forest enginee...
18. Underwater-cable power-transmission system: bottom segment design
1978-11-01
After a survey of the state of the art for bottom cables, some possible configurations are considered for candidate OTEC sites. General considerations on laying and embedding are discussed, and solutions are considered. Optimization of cable dimensions and the problem of flexible joints are covered. The state of the art of cable installation and repair is reviewed and discussed with reference to the representative OTEC sites. Costs for shore terminal stations are evaluated. (LEW)
19. Demand Pull and Supply Push in Portuguese Cable Television
João Leitão
2004-01-01
In this paper a Vector Autoregressive Model is applied to the most representative Portuguese cable television operators, in order to obtain a dynamic analysis of the interactivity established between the supply and the demand of network services, through the strategy of vertical integration of services. The results reveal the existence of two driving forces in the Portuguese main cable networks, on the one hand, the supply push which contributes to the enhancement of the basic cable demand, a...
20. Losses in armoured three-phase submarine cables
Ebdrup, Thomas; Silva, Filipe Miguel Faria da; Bak, Claus Leth;
2014-01-01
The number of offshore wind farms will keep increasing in the future as a part of the shift towards a CO2 free energy production. The energy harvested from the wind farm must be brought to shore, which is often done by using a three-phase armoured submarine power cable. The use of an armour...... increases the losses in armoured cables compared to unarmoured cables. In this paper a thorough state of the art analysis is conducted on armour losses in three-phase armoured submarine power cables. The analysis shows that the IEC 60287-1-1 standard overestimates the armour losses which lead to the...
1. Magnetic Flux Leakage Sensing-Based Steel Cable NDE Technique
Seunghee Park
2014-01-01
Full Text Available Nondestructive evaluation (NDE of steel cables in long span bridges is necessary to prevent structural failure. Thus, an automated cable monitoring system is proposed that uses a suitable NDE technique and a cable-climbing robot. A magnetic flux leakage- (MFL- based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults (LF of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the levels of damage. Measured signals from the damaged specimen were compared with thresholds that were set for objective decision-making. In addition, the measured magnetic flux signals were visualized as a 3D MFL map for intuitive cable monitoring. Finally, the results were compared with information on actual inflicted damages, to confirm the accuracy and effectiveness of the proposed cable monitoring method.
2. Modeling and Experiments of Spray System for Cable Painting Robot
ZHANG Jia-liang; Lü Tian-sheng; LI Bei-zhi
2008-01-01
Many cable-stayed bridges have been built in the world in the past decades,and cable-stayed structures have been adopted in many large constructions.The cable painting robot is safe and economically efficient for stay cable maintenance.In order to satisfy the need for spraying cables in hiigh attitude,an automatic cable spray system for cable painting robots is presented in this paper.Using the βdistribution,paint thickness distribution on a cylinder surface is modeled.The spray gun's number,angle and movement are analyzed to get coat evenness.Then a robotic spray system engineering prototype has been developed,which includes a cable electric running climbing base,a spray cover,four airless spray guns and a pressurized paint container.Experiments indicate that four airless spray guns can guarantee good coat quality for general stay cables.The field tests have been successfully conducted on Nanpu Bridge,Shanghai.
3. Modelling Subsea Coaxial Cable as FIR Filter on MATLAB
Kanisin, D.; Nordin, M. S.; Hazrul, M. H.; Kumar, E. A.
2011-05-01
The paper presents the modelling of subsea coaxial cable as a FIR filter on MATLAB. The subsea coaxial cables are commonly used in telecommunication industry and, oil and gas industry. Furthermore, this cable is unlike a filter circuit, which is a "lumped network" as individual components appear as discrete items. Therefore, a subsea coaxial network can be represented as a digital filter. In overall, the study has been conducted using MATLAB to model the subsea coaxial channel model base on primary and secondary parameters of subsea coaxial cable.
4. Research on Cable Assembly Technology Facing Tridimention Layout in Spacecraft
Song, Xiaohui; Liu, Zhe; Wang, Zaicheng; Zhang, Yidan; Zhang, Jie; Liu, Zhibin
According to the requirement for cables tridimensional layout in spacecraft, the research on new transmission line support (NTLS) is carried out. NTLS is namely T support. Based on the analysis of NTLS's physical parameters, the scheme of cable installing is established. Experimentations of statics and vibration prove the feasibility and dependability of the scheme. The results of experimentation indicate that the scheme of cable installing on T support is reasonable along with the requirement of cables tridimensional layout is satisfied. Therefore the efficiency of spacecraft assembly and integration is greatly enhanced.
5. Strand critical current degradation in $Nb_{3}$ Sn Rutherford cables
Barzi, E; Higley, H C; Scanlan, R M; Yamada, R; Zlobin, A V
2001-01-01
Fermilab is developing 11 Tesla superconducting accelerator magnets based on Nb/sub 3/Sn superconductor. Multifilamentary Nb/sub 3/Sn strands produced using the modified jelly roll, internal tin, and powder-in-tube technologies were used for the development and test of the prototype cable. To optimize the cable geometry with respect to the critical current, short samples of Rutherford cable with packing factors in the 85 to 95% range were fabricated and studied. In this paper, the results of measurements of critical current, n-value and RRR made on the round virgin strands and on the strands extracted from the cable samples are presented. (5 refs).
6. Development mineral insulated cables for nuclear instrumentation of reactors
In-core and out-of-core neutron detectors for reactor and safety control systems are usually connected by means of mineral insulated cables. The electrical signal, either a pulse or a current, is transmitted along the cable at high temperature, pressure and radiation and should not be influenced by electromagnetic interfereces from the environment. In this paper it is presented the result of the analysis of the mechanical and electrical properties of several types of mineral insulated cables and also the design, manufacture, sealing, cable ends and their applications to nuclear detectors of various types. (author)
7. BEHAVIOR OF ELASTIC TOWING CABLES IN SHEAR CURRENTS
HOU Guo-xiang; LI Hong-bin; ZHANG Sheng-jun; YANG Yun-tao; XU Shi-hua; XIE Wei
2005-01-01
The formulation and solution of governing equations that can be used to analyse the three-dimensional behaviour of elastic towing cables subjected to arbitrary sheared currents were presented in this paper. The elastic cable geometry was described in terms of two angles, elevation and azimuth, which are related to Cartesian co-ordinates by geometry compatibility relations. These relations were combined with the cable equilibrium equations to obtain a system of non-linear differential equations. In the end, results for cable tension, angles, geometry and elongation are presented for example cases.
8. 30 CFR 57.20031 - Blasting underground in hazardous areas.
2010-07-01
... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Blasting underground in hazardous areas. 57... MINES Miscellaneous § 57.20031 Blasting underground in hazardous areas. In underground areas where... removed to safe places before blasting....
9. Technologies for placing of underground installations
Doneva, Nikolinka; Despodov, Zoran; Mirakovski, Dejan; Hadzi-Nikolova, Marija
2014-01-01
In urban communities often there is a need to change existing underground installations or placing new ones. This paper will discuss two technologies for placing underground installations including: classic and contemporary technology (technology with mechanical excavation). For each of these two technologies will be given advantages and disadvantages, as well as experiences from their application.
10. UNDERGROUND ECONOMY, INFLUENCES ON NATIONAL ECONOMIES
CEAUȘESCU IONUT
2015-01-01
The purpose of research is to improve the understanding of nature underground economy by rational justification of the right to be enshrined a reality that, at least statistically, can no longer be neglected. So, we propose to find the answer to the question: has underground economy to stand-alone?
11. Underground location of nuclear power stations
In Japan where the population is dense and the land is narrow, the conventional location of nuclear power stations on the ground will become very difficult sooner or later. At this time, it is very important to establish the new location method such as underground location, Quaternary ground location and offshore location as the method of expanding the location for nuclear power stations from the viewpoint of the long term demand and supply of electric power. As for underground location, the technology of constructing an underground cavity has been already fostered basically by the construction of large scale cavities for underground pumping-up power stations in the last 20 years. In France, Norway and Sweden, there are the examples of the construction of underground nuclear power stations. In this way, the opportunity of the underground location and construction of nuclear power stations seems to be sufficiently heightened, and the basic research has been carried out also in the Central Research Institute of Electric Power Industry. In this paper, as to underground nuclear power stations as one of the forms of utilizing underground space, the concept, the advantage in aseismatic capability, the safety at the time of a supposed accident, and the economical efficiency are discussed. (Kako, I.)
12. UNDERGROUND ECONOMY, INFLUENCES ON NATIONAL ECONOMIES
CEAUȘESCU IONUT
2015-04-01
Full Text Available The purpose of research is to improve the understanding of nature underground economy by rational justification of the right to be enshrined a reality that, at least statistically, can no longer be neglected. So, we propose to find the answer to the question: has underground economy to stand-alone?
13. Overview of the European Underground Facilities
Pandola, L
2011-01-01
Deep underground laboratories are the only places where the extremely low background radiation level required for most experiments looking for rare events in physics and astroparticle physics can be achieved. Underground sites are also the most suitable location for very low background gamma-ray spectrometers, able to assay trace radioactive contaminants. Many operational infrastructures are already available worldwide for science, differing for depth, dimension and rock characteristics. Other underground sites are emerging as potential new laboratories. In this paper the European underground sites are reviewed, giving a particular emphasis on their relative strength and complementarity. A coordination and integration effort among the European Union underground infrastructures was initiated by the EU-funded ILIAS project and proved to be very effective.
14. Comparison of FT-IR and NIR method for cable classification
There are about 50,000 cables in NPP. The number of the cables need to be environmentally qualified are 1,000 cables to 3,000 cables depending on the NPP respectively. Some EQ cables are environmentally qualified and the steam test reports prepared, but some other EQ cables are not environmentally qualified or not prepared steam test reports. Not qualified EQ cables need to be qualified by steam test; high temperature and high pressure with the same condition of DBAs. There are thousands of EQ cables in NPP but all the EQ cables don't have to be tested entirely. The steam tests can be carried out by the same types of cables. One type of cable is tested and demonstrated that the cable's capability for the duration of the installed life, all the same type of cables are qualified. Therefore, the classification the EQ cables is very important to carry out the steam test effectively. Also cable classification method selection is important, too. I tried two kinds of methods to classify the Wolsong Unit 1 EQ cables, Near InfraRed (NIR) spectroscopy and Fourier Transform InfraRed (FT-IR) spectroscopy. In case of old NPPs, lots of cables are missing their material information or have the wrong material information. The two methods are capable of searching for the material information of the cable. Briefly, the purpose FT-IR and NIR scanning is to find out their material information and classification of the EQ cables
15. Development of a low-cost cableless geophone and its application in a micro-seismic survey at an abandoned underground coal mine
Dai, Kaoshan; Li, Xiaofeng; Lu, Chuan; You, Qingyu; Huang, Zhenhua; Wu, H. Felix
2015-04-01
Due to the urbanization in China, some building construction sites are planned on areas above abandoned underground mines, which pose a concern for the stability of these sites and a critical need for the use of reliable site investigations. The array-based surface wave method has the potential for conducting large-scale field surveys at areas above underground mines. However, the dense deployment of conventional geophones requires heavy digital cables. On the other hand, the bulky and expensive standard stand-alone seismometers limit the number of stations for the array-based surface wave measurements. Therefore, this study developed a low-cost cableless geophone system for the array-based surface wave survey. A field case study using this novel cableless geophone system was conducted at an abandoned underground mine site in China to validate its functionality.
16. Chemical-Sensing Cables Detect Potential Threats
2007-01-01
Intelligent Optical Systems Inc. (IOS) completed Phase I and II Small Business Innovation Research (SBIR) contracts with NASA's Langley Research Center to develop moisture- and pH-sensitive sensors to detect corrosion or pre-corrosive conditions, warning of potentially dangerous conditions before significant structural damage occurs. This new type of sensor uses a specially manufactured optical fiber whose entire length is chemically sensitive, changing color in response to contact with its target, and demonstrated to detect potentially corrosive moisture incursions to within 2 cm. After completing the work with NASA, the company received a Defense Advanced Research Projects Agency (DARPA) Phase III SBIR to develop the sensors further for detecting chemical warfare agents, for which they proved just as successful. The company then worked with the U.S. Department of Defense (DoD) to fine tune the sensors for detecting potential threats, such as toxic industrial compounds and nerve agents. In addition to the work with government agencies, Intelligent Optical Systems has sold the chemically sensitive fiber optic cables to major automotive and aerospace companies, who are finding a variety of uses for the devices. Marketed under the brand name Distributed Intrinsic Chemical Agent Sensing and Transmission (DICAST), these unique continuous-cable fiber optic chemical sensors can serve in a variety of applications: Corrosive-condition monitoring, aiding experimentation with nontraditional power sources, as an economical means of detecting chemical release in large facilities, as an inexpensive "alarm" systems to alert the user to a change in the chemical environment anywhere along the cable, or in distance-resolved optical time domain reflectometry systems to provide detailed profiles of chemical concentration versus length.
17. The technology of cable and cable fault locating : part 4, high voltage non persistent fault finding
Parker, G. [Radiodetection Ltd., Calgary, AB (Canada)
2001-04-01
The use of high voltage surge generators known as 'thumpers' was discussed in this last of a four part series on cable and fault locating technologies. The thumper is a portable source of high voltage, which repeatedly connects high voltage to a buried cable under test (CUT). The problem often associated with thumpers is that different ground conditions, vehicle traffic patters and fault types can make the noise they generate difficult to discern. In addition, repeated thumping can have negative side effects to the CUT, including weakening of adjacent cables. Thumped cables also fail prematurely, therefore thumping should be used only as a last resort. Advancements in thumper systems have included better listening devices, and the integration of safety systems, self-discharge systems, grounding, manual discharge hot-sticks, key switch lockouts and other methods to minimize injury. Other advancements have included a visual pre-locator which made the thumper more like a high voltage TDR. Pre-locators usually indicate the fault with an accuracy of 10 to 15 per cent. The Secondary Impulse Method (SIM) is the latest development in thumper technology. It was developed mainly to enhance trace interpretation. 2 figs.
18. Performances of super-long span prestressed cable-stayed bridge with CFRP cables and RPC girder
Fang Zhi; Fan Fenghong; Ren Liang
2013-01-01
To discuss the applicability of advanced composite carbon fiber reinforced polymer (CFRP) and ultra-high performance concrete reactive powder concrete (RPC) in super-long span cable-stayed bridges , taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable’s cross section was determined by the principle of equivalent cable capacity and the girder’s cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resis-tance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.
19. Depleted Argon from Underground Sources
Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.
20. Radionuclide behavior at underground environment
This study of radionuclide behavior at underground environment has been carried out as a part of the study of high-level waste disposal technology development. Therefore, the main objectives of this project are constructing a data-base and producing data for the safety assessment of a high-level radioactive waste, and verification of the objectivity of the assessment through characterization of the geochemical processes and experimental validation of the radionuclide migration. The various results from the this project can be applicable to the preliminary safety and performance assessments of the established disposal concept for a future high-level radioactive waste repository. Providing required data and technical basis for assessment methodologies could be a direct application of the results. In a long-term view, the results can also be utilized as a technical background for the establishment of government policy for high-level radioactive waste disposal
|
__label__pos
| 0.796667 |
Task-Per-Derivative: 1 Task-Section: user Task-Description: Xubuntu desktop Task-Extended-Description: This task provides the Xubuntu desktop environment. Task-Key: xubuntu-desktop Task-Name: xubuntu-desktop Task-Seeds: desktop-common = Hardware and Architecture Support = == Architecture-independent == * libgd2-xpm # force the xpm-enabled version for edubuntu compatibility = Network Services = Basic network services and Windows integration. * (avahi-autoipd) # IPv4 link-local interface configuration support * (network-manager-gnome) # see NetworkRoaming spec * (network-manager-pptp) * (network-manager-pptp-gnome) = GUI infrastructure = * xterm # Provide a backup terminal and complete X env. Extra fonts (should be common, but not so for space reasons): * (ttf-wqy-microhei) * (ttf-unfonts-core) * (ttf-opensymbol) * (ttf-liberation) Input methods: * (im-switch) * (ibus) * (ibus-gtk) * (ibus-table) * (ibus-pinyin) * (ibus-pinyin-db-android) = Desktop Xfce Apps = Common with Ubuntu: * (apport-gtk) * desktop-file-utils * (file-roller) * (gcalctool) * gdm * software-center * (app-install-data-partner) * (gnome-codec-install) # new default codec installation tool (from debian) * (transmission-gtk) # simple GNOME frontend for bittorrent downloads * (system-config-printer-gnome) * (libpam-gnome-keyring) * (gnome-system-tools) * (gucharmap) # SebastienBacher * language-selector # MichaelVogt * (firefox) * (firefox-gnome-support) * (ubufox) # ubuntu firefox tweaks - AlexanderSack * rarian-compat * synaptic # default GUI package manager * (libgnome2-perl) # so that the debconf GNOME frontend can be used from synaptic * software-properties-gtk # default GUI sources.list editor * update-manager * (update-notifier) * gdebi #TODO: drop it in natty, too late for maverick * zenity * (xdg-utils) # useful utilities * xdg-user-dirs * xdg-user-dirs-gtk * (gvfs-fuse) # let non-GNOME apps see GVFS via fuse Xfce core: * xfwm4 * xfdesktop4 * xfce4-panel * xfce4-utils * xfce4-settings * xfce4-session * thunar * (xfce4-appfinder) Xfce goodies: * (xfce4-mailwatch-plugin) * (xfce4-fsguard-plugin) * (xfce4-verve-plugin) * (xfce4-clipman-plugin) # drop it from the seeds when xfce4-settings >= 4.7.1 is here * (xfce4-mount-plugin) * (xfce4-quicklauncher-plugin) * (xfce4-weather-plugin) * (xfce4-xkb-plugin) * (xfce4-cpugraph-plugin) * (xfce4-systemload-plugin) * (xfce4-netload-plugin) * (xfce4-screenshooter) * (xfce4-notes-plugin) * (xfce4-smartbookmark-plugin) * (xfce4-dict) * (xfce4-places-plugin) * (xfce4-mixer) * (xfswitch-plugin) * (thunar-archive-plugin) * (thunar-media-tags-plugin) * (thunar-thumbnailers) * thunar-volman * (xfprint4) # Deprecated in Xfce 4.6 but still required by mousepad 0.2.x * (xfce4-volumed) # Developed and maintained by Xubuntu's own SiDi :) * (xfce4-terminal) * (orage) * (mousepad) * (ristretto) * (xfce4-power-manager) * (gigolo) * (xfce4-taskmanager) * (xfburn) * (parole) * (browser-plugin-parole) Games: We only ship a few by default. * (aisleriot) * (gnome-mahjongg) * (gnomine) * (gnome-sudoku) * (quadrapassel) Themes: * gtk2-engines # DanielHolbach (gtk2-engines were merged into one package) * gtk2-engines-pixbuf # Required by some themes the user might install * gtk2-engines-xfce * gtk2-engines-murrine * tango-icon-theme * tango-icon-theme-common * dmz-cursor-theme The gstreamer0.10 packages we want to install: * (gstreamer0.10-alsa) * (gstreamer0.10-plugins-base-apps) * libasound2-plugins Accessibility tools: * (gnome-accessibility-themes) * (onboard) * (brltty) * (brltty-x11) * (xcursor-themes) * (espeak) * (speech-dispatcher) = Other Desktop GUI Apps = * (evince) * (gnumeric) * (abiword) * (abiword-plugin-grammar) * (abiword-plugin-mathview) * (xscreensaver) * (screensaver-default-images) * (xscreensaver-gl) * (xscreensaver-data) * (jockey-gtk) # enable non-free graphics and other drivers easily * (usb-creator-gtk) [i386 amd64 lpia] * (simple-scan) * (catfish) * (gimp) * (exaile) * (thunderbird) * (pidgin) * (pidgin-otr) * (vinagre) * (xchat) Desktop Experience: * (notify-osd) # backend for libnotify = Documentation = * doc-base # integrates with scrollkeeper * (xubuntu-docs) = Development = Here we provide a minimal development environment sufficient to build kernel drivers, so that this is possible on the live CD and in scenarios where it is problematic to get these packages onto the installed system in order to compile a driver. -mdz * (gcc) * (make) * (linux-headers-generic) [i386] * (linux-headers-generic) [amd64] * (linux-headers-ia64) [ia64] * (linux-headers-sparc64) [sparc] * (linux-headers-hppa32) [hppa] * (linux-headers-hppa64) [hppa] * (linux-headers-lpia) [lpia] * (linux-headers-dove) [armel] = Other = * xubuntu-desktop # metapackage for everything here * xubuntu-default-settings * (xubuntu-artwork) * hal
|
__label__pos
| 0.999976 |
AcceleratedSurfaceWayland.h [plain text]
/*
* Copyright (C) 2016 Igalia S.L.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#if PLATFORM(WAYLAND)
#include "AcceleratedSurface.h"
#include "WebPage.h"
#include <WebCore/WlUniquePtr.h>
#include <wayland-egl.h>
namespace WebKit {
class AcceleratedSurfaceWayland final : public AcceleratedSurface {
WTF_MAKE_NONCOPYABLE(AcceleratedSurfaceWayland); WTF_MAKE_FAST_ALLOCATED;
public:
static std::unique_ptr<AcceleratedSurfaceWayland> create(WebPage&, Client&);
~AcceleratedSurfaceWayland() = default;
uint64_t window() const override { return reinterpret_cast<uint64_t>(m_window); }
uint64_t surfaceID() const override { return m_webPage.identifier().toUInt64(); }
void clientResize(const WebCore::IntSize&) override;
bool shouldPaintMirrored() const override { return true; }
void initialize() override;
void finalize() override;
void didRenderFrame() override;
private:
AcceleratedSurfaceWayland(WebPage&, Client&);
WebCore::WlUniquePtr<struct wl_surface> m_surface;
struct wl_egl_window* m_window { nullptr };
};
} // namespace WebKit
#endif // PLATFORM(WAYLAND)
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| 0.960895 |
ABSTRACT
Reconfigurable hardware has evolved to become Reconfigurable Systemon-Chips (RSoCs). Many modern reconfigurable hardware integrates generalpurpose processor cores, reconfigurable logic, memory, etc., on a single chip. This is driven by the advantages of programmable design solutions over application specific integrated circuits and a recent trend in integrating configurable logic (e.g., FPGA, and programmable processors), offering the “best of both worlds” on a single chip.
|
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| 0.693316 |
The Non-Technical Founder’s Common Tech Terms for Building Your Product
Nolte non technical founder
In today’s digital age, having a technical co-founder isn’t the only path to turning your brilliant idea into a digital product. If you’re a non-technical founder with a vision, you can make it a reality. This article is your guide to understanding the essentials of tech, from coding languages to security, enabling you to embark on your founder journey confidently.
Common Coding Languages and Their Uses
Before diving into the intricacies of tech, let’s start with the basics by exploring the fundamental coding languages and their specific roles in software development.
HTML
HTML is the cornerstone of web content structuring, allowing you to define the structure of your web pages.
CSS
CSS (Cascading Style Sheets) complements HTML by enabling you to add style and aesthetics to your web content.
JavaScript
As a versatile and dynamic scripting language, JavaScript adds interactivity, responsiveness, and functionality to websites and web applications.
Python
Renowned for its simplicity and readability, Python finds applications in web development, data analysis, and various other fields.
Ruby
Praised for its user-friendly syntax, Ruby is a popular choice for web development and building dynamic web applications.
Frameworks and Platforms: What Are They and Why Are They Important?
Frameworks and platforms are the scaffolding upon which your digital product is constructed and streamline development processes. Here’s what you need to know.
Frameworks
Frameworks are pre-established structures provide a systematic foundation for application development. By leveraging a framework, you save valuable time and effort while ensuring best practices are followed.
Platforms
Platforms furnish the environment necessary for hosting and deploying your digital product. Platforms like AWS (Amazon Web Services) and Azure offer scalability, reliability, and security for your projects.
Understanding the Cloud and Its Components
The cloud is the digital realm where your product’s data and services reside. Here’s a closer look at its components.
Cloud Services
Offered by providers like AWS and Google Cloud, Cloud Services grant you access to scalable and flexible infrastructure for your digital product.
Data Storage
Data Storage is made up of cloud-based repositories that enable seamless storage and retrieval of your data, ensuring it remains accessible and secure.
Key Terms in Software Development
Your software development team may mention these terms when they communicate with you about your digital product. Here are their definitions.
API
API (Application Programming Interface) acts as an intermediary, allowing different software components to communicate with one another. APIs are the building blocks of modern software development.
UI/UX
UI (User Interface) & UX (User Experience) encompass the design and user-friendliness of your product. A well-crafted UI/UX is vital for user satisfaction and engagement.
Frontend and Backend
Frontend deals with the visual aspects and user interactions, while the Backend manages the underlying processes, databases, and server-side operations.
Database Basics: SQL vs. NoSQL
Databases serve as the repository for your digital product’s data. Two primary database types are SQL and NoSQL.
SQL
SQL (Structured Query Language) databases excel at managing structured data. They are reliable, ensure data integrity, and are often used in complex data systems.
NoSQL
NoSQL (Not Only SQL) databases are renowned for their flexibility, making them suitable for handling unstructured or semi-structured data. They are preferred for projects requiring scalability and quick iterations.
The Difference Between Web Apps, Mobile Apps, and Desktop Apps
Understanding the various application types is pivotal to your non-technical founder journey.
Web Apps
Web Applications run within web browsers, making them accessible across various devices with internet connectivity.
Mobile Apps
Mobile Apps are specifically designed for smartphones and tablets, mobile apps offer a tailored user experience, taking advantage of mobile device capabilities.
Desktop Apps
Desktop Apps are installed directly on computers and laptops, desktop apps provide more robust functionality and offline capabilities.
Security Essentials: Encryption, Two-Factor Authentication, VPN
Ensuring the security of your digital product is paramount.
Encryption
Encryption is a security measure that protects your data from unauthorized access by converting it into unreadable code that can only be deciphered with the correct encryption key.
Two-Factor Authentication
Adding an extra layer of security, 2FA (Two-Factor Authentication) requires users to provide two forms of verification before granting access, significantly enhancing security.
VPN
VPNs (Virtual Private Network) are indispensable for safeguarding your online activities by creating secure, encrypted connections, particularly when using public Wi-Fi networks.
Now that you’ve gained a profound understanding of these tech essentials, you’re better prepared to embark on your digital product journey. Remember, learning is an ongoing process, and you don’t need to become a tech guru overnight.
Collaboration with tech-savvy individuals and maintaining curiosity will be your allies in this exciting endeavor. Becoming a non-technical founder and creating a digital product is not only feasible but also a rewarding journey. Embrace the learning process, seek guidance when needed, and stay curious. Your determination and vision can transform your ideas into reality in the digital realm.
FAQs
1. Is it necessary to learn coding languages as a non-technical founder?
While it’s not mandatory, having a basic understanding can significantly enhance communication with your development team and help you make informed decisions.
2. What are the advantages of using a framework in development?
Frameworks provide a structured, efficient foundation for your project, reducing development time and ensuring best practices are followed.
3. How can I ensure the security of my digital product?
Implement robust security measures such as encryption, two-factor authentication (2FA), and consider using a Virtual Private Network (VPN) to protect your product and user data.
4. Which database type, SQL or NoSQL, is more suitable for my project?
The choice depends on your project’s specific requirements and data structure. Consult with experts or your development team to make an informed decision.
5. Can I successfully build a digital product without a technical co-founder?
Absolutely! Many successful digital products have been created by non-technical founders. By partnering with a vetted technical partner like Nolte, you can successfully launch a digital product with full control over your vision.
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|
__label__pos
| 0.891557 |
PDA
View Full Version : HTML tag/node frequency statistics
Harry Armadillo
03-16-2005, 07:04 PM
A script I'm building needs to look at and fiddlle with nearly every node in the document's body. To make it run as fast as possible, the switch/case statement (that decides what to do based on what kind of node it is) needs to be in the optimum order - common to rare.
For example: I don't care about #comment nodes. Are they common enough that a case '#comment': break; will save time? Or are they uncommon enough that it'll be faster to let them fall out the bottom of the switch (despite having to checked them against more case statements)?
Does anyone know where I can find (or how can I generate) statistics on the relative frequency of nodes? I can examine pages myself one at a time (I have a bookmarklet that pops up a window with how many of each node type), but it would be too tedious to manually examine enough pages for good stats on the rarer tags.
vwphillips
03-16-2005, 08:03 PM
is this of any assistance?
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title></title>
<script language="JavaScript" type="text/javascript">
<!--
EAry=new Array('IMG','INPUT');
PAry=new Array();
function Priority(){
for (i=0;i<EAry.length;i++){
PAry[i]=new Array();
PAry[i][0]=EAry[i];
PAry[i][1]=document.getElementsByTagName(EAry[i]).length;
}
PAry.sort(tsoSortNumeric);
document.Show.Show1.value=PAry;
}
function tsoSortNumeric(tso0,tso1){
tsoA=tso0[1]; tsoB=tso1[1];
if (isNaN(tsoA)){ return 0;}
else {
if (isNaN(tsoB)){ return 0; }
else { return tsoA-tsoB; }
}
}
//-->
</script>
</head>
<body onload="Priority();" >
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<img src="111.gif" width="10" height="10">
<script> vic=0; </script>
<form name=Show id=Show style="position:absolute;visibility:visible;top:450px;left:0px;" >
<input size=100 name=Show1 >
<input size=10 name=Show2 >
<input size=10 name=Show3 >
<input size=10 name=Show4 >
<input size=10 name=Show5 >
<input size=10 name=Show6 >
</form>
</body>
</html>
Harry Armadillo
03-16-2005, 10:52 PM
Yeah, my bookmarklet does basically the same thing, only moreso.
javascript:(function(){var total=new Array();function sortThem(a,b){return(b.count-a.count)}function countObj(nodeName){this.nodeName=nodeName;this.count=1;}function totalNodes(obj){var i=total.length;var n=obj.nodeName.toLowerCase();dude:{while(i--){if(n==total[i].nodeName){total[i].count++;break dude;};}total[total.length]=new countObj(n);}for(var i=0;i<obj.childNodes.length;i++)totalNodes(obj.childNodes[i])}totalNodes(document.body);total.sort(sortThem);var w=window.open('','_blank');for(var i=0;i<total.length;i++)w.document.write(total[i].count+" "+total[i].nodeName+"<br>");w.document.close();})()Readable version:
javascript:(function(){
var total=new Array();
function sortThem(a,b){
return(b.count-a.count)
}
function countObj(nodeName){
this.nodeName=nodeName;
this.count=1;
}
function totalNodes(obj){
var i=total.length;
var n=obj.nodeName.toLowerCase();
dude:{
while(i--){
if(n==total[i].nodeName){
total[i].count++;
break dude;
};
}
total[total.length]=new countObj(n);
}
for(var i=0;i<obj.childNodes.length;i++)
totalNodes(obj.childNodes[i])
}
totalNodes(document.body);
total.sort(sortThem);
var w=window.open('','_blank');
for(var i=0;i<total.length;i++)
w.document.write(total[i].count+" "+total[i].nodeName+"<br>");
w.document.close();
})()
Which gives me something like this for this page:
819 #text
125 font
86 br
81 #comment
79 a
71 div
56 td
37 option
33 tr
22 img
21 strong
16 table
16 tbody
15 input
6 span
6 script
4 form
4 b
3 optgroup
2 select
2 p
2 code
2 hr
1 i
1 body
1 thead
That's great for a single page, but I need that sort of list for the 'average' page (or for the web as a whole...). I could generate that sort of list on a bunch of random pages (and have), but I don't have an easy way to total them over a ton of pages.
liorean
03-16-2005, 11:00 PM
Why don't you let it build the source code for a JavaScript object. Then you run it on twenty different sites and get twenty objects that you place in an array. Add together all nodes of the same kind to a total, and divide by twenty, and you have the average.
Harry Armadillo
03-16-2005, 11:31 PM
How do I do that on twenty pages from twenty different sites without triggering cross-site scripting warnings?
codegoboom
03-17-2005, 12:05 AM
There's a discussion about that kind of thing and xml http requests a few threads down, I think... (i'd probably just visit a bunch of sites in IE, and then read files from the cache, using the Shell/FSO).
liorean
03-17-2005, 02:10 AM
Harry: You don't. Twenty sites is low enough to collect one object literal for each manually. Then you manually enter those into the source code of the script that calculates the averages..
You see, the time you took for worrying about how to do it automatically is probably way larger than it would have been to do it manually.
Vladdy
03-17-2005, 03:33 AM
Eliminate the root of the problem....
processNode = new Array();
processNode['font'] = function(node)
{ /* process font node */
};
processNode['p'] = function(node)
{ /* process paragraph node */
};
function doNode(node)
{ processNode[node.nodeName](node);
}
glenngv
03-17-2005, 05:03 AM
I did a rough performance test on both solutions (hash and switch) and found interesting results for IE6 and Firefox. Their results are contrasting. In IE, hash is faster than switch but the other way around for FF and it's also interesting to note that FF is much faster (about twice as fast) than IE in processing the code. Here's the code and the results:
script:
//for hash
var processNode = new Array();
processNode['font'] = function(node)
{ /* process font node */
};
processNode['p'] = function(node)
{ /* process paragraph node */
};
processNode['div'] = function(node)
{ /* process div node */
};
function doNode(node)
{ processNode[node](node);
}
function process(node){
var s = new Date();
for (var i=0;i<100000;i++){
doNode(node);
}
var e = new Date();
var d = (e-s)/1000;
alert(d);
document.getElementById('output1').innerHTML+=d+' '+node+'<br />';
}
//for switch
function doNode2(node)
{
switch (node){
case 'font':processNode2(node);break;
case 'p':processNode2(node);break;
case 'div':processNode2(node);break;
}
}
function processNode2(node){
/* process node */
}
function process2(node){
var s = new Date();
for (var i=0;i<100000;i++){
doNode2(node);
}
var e = new Date();
var d = (e-s)/1000;
alert(d);
document.getElementById('output2').innerHTML+=d+' '+node+'<br />';
}
form:
<form>
<div>
<input type="button" value="hash" onclick="process(prompt('node?',''))" />
<div id="output1"></div>
</div>
<hr />
<div>
<input type="button" value="switch" onclick="process2(prompt('node?',''))" />
<div id="output2"></div>
</div>
</form>
Results:
hash (IE) switch (IE) hash (FF) switch (FF)
1.112 div 1.262 div 0.631 div 0.571 div
1.101 div 1.261 div 0.641 div 0.56 div
1.102 div 1.261 div 0.641 div 0.561 div
1.102 div 1.251 div 0.641 div 0.561 div
1.102 div 1.252 div 0.641 div 0.56 div
1.102 p 1.212 p 0.631 p 0.551 p
1.092 p 1.212 p 0.631 p 0.551 p
1.101 p 1.212 p 0.641 p 0.551 p
1.092 p 1.202 p 0.631 p 0.55 p
1.101 p 1.212 p 0.631 p 0.551 p
1.101 font 1.161 font 0.641 font 0.541 font
1.112 font 1.162 font 0.651 font 0.541 font
1.102 font 1.161 font 0.651 font 0.541 font
1.101 font 1.162 font 0.651 font 0.541 font
1.111 font 1.162 font 0.641 font 0.541 font
After I executed all the repetitions for hash method, I refreshed the page then execute the items for the switch method to make the scenario even.
Harry Armadillo
03-17-2005, 05:33 AM
Vladdy...won't work. The parent/child/sibling/grandparent/cousin relationships count, so I gotta just walk the the tree.
liorean, haven't you even had a puzzle that you just had to crack? Do I need to spend six hours figuring out how to cut a script down from 600 to 500 ms of run time? No, but I am going to. :) Anyway I found some code from your xml http postings - I didn't realize the IE5.5 would let you do out of domain xmlhttp requests.
I as type this, an ugly hunk of code is pulling urls from a list in a textarea, grabbing the html, chopping off the pieces I don't want, and dumping the rest into an iframe. Then a script totals up the different types of nodes and updates an output area.
IE5.5 seems the parse HTML into a slight different tree tha Firefox (not to mention how IE creates nodes from broken tags), so I still want to figure out how to do something similar in FF.
Meanwhile, it's nice to know that small is five time as common as blockquote and that #text is 185 times more common than hr.
codegoboom
03-17-2005, 11:36 AM
I still want to figure out how to do something similar in FF.
That may be documented on xulplanet (if not, just save the source files, and read them locally). ;)
Harry Armadillo
03-17-2005, 07:14 PM
Not being the sort of person who stops just because something may be pointless...I tried hashes.
The various functions all wanted different sets of parameters, so I end up building an object containing the minimal set and passed a reference to it. With the extra overhead, hashes are a lot slower. Especially with the error handling needed with IE's habit of making pointless nodes from broken tags (an '/img' node? a 'C160DB3548BEA4' node?)
FWIW, this the relative frequency I found in the bodies of a sample of 3021 pages:
31.2818 #text
9.5278 br
9.1822 a
7.4688 td
6.2378 font
4.7963 tr
3.9655 img
3.8765 p
3.5474 span
3.2721 b
2.2265 ! or #comment
2.1986 center
1.7305 tbody
1.6318 table
1.5344 div
0.9987 option
0.9682 nobr
0.8739 li
0.8541 input
0.5880 i
0.3109 strong
0.2909 spacer
0.2580 hr
0.2282 noscript
0.2156 script
0.2067 small
0.1776 area
0.1602 form
0.1547 u
0.1535 ul
0.1340 dd
0.1056 body
0.0782 sub
0.0738 em
0.0671 big
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Harry Armadillo
03-19-2005, 07:33 AM
For compiling my stats with a real browser, the key line is
netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
which causes Firefox to ask if I want to allow a script to do potentially unsafe and obviously evil things. Which of course I do. :)
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| 0.811274 |
What is moisture mapping?
When water damage occurs, insurance companies and clean up crews are affected. The first question to ask is, how extensive is the damage? Moisture mapping is a way of visually representing the moisture levels in a property. This means everyone can clearly understand where the wet zone (damage) ends and the dry zone (undamaged) begins.
So will I get a moisture map of my property?
A moisture map can be presented as a paper map or a computer summary. It may also be marked on the material (usually walls or floor) in question, with chalk, pen, tape or another marking material. Making marks on your property ensure it’s clear where the wet zone ends and the dry zone begins. Depending on the damage it may be unsuitable to walk on the wet zone. In this case, having a visual boundary is useful.
How is moisture measured?
Moisture can be detected in a variety of ways. Some being more sophisticated than others (ever stepped on a soggy carpet?) The high tech tools are typically only used around the perimeter of the wet zone, to understand exactly where the wet zone and dry zone meet. These tools include infrared cameras and moisture meters.
Why does this moisture map say my dry zone is damp too?
All buildings have a certain level of naturally occurring moisture. If you’ve been given a printed moisture map, it may indicate this level as the moisture of the dry zone. It may also vary across the building, and again this can be completely normal. For example, picture a leisure centre. The sauna and swimming pool areas will be incredibly moist, without a leak, the changing room (with its showers) quite moist and reception less moist.
Will my moisture map change?
Yes. One of the most useful features of moisture mapping is that it indicates if the damp is spreading or shrinking. If a pipe bursts under the floor then an hour-by-hour update would show the water spreading then stopping when the mains water supply was switched off. The wet zone might shrink as efforts were made to dry out the property, but grow again if the water was switched back on before an effective repair was completed. Typically, moisture mapping will be done at long intervals – less than once a week – as it takes time to dry a property. Spot checks will occur if the contractor doing the drying has any concerns.
Why do I have islands of damp on my moisture map?
Water moves consistently, but that doesn’t mean it will affect a room evenly. This is particularly true where the water is moving mainly through hidden channels and the effects are being seen at one remove, such as when water is underneath floorboards.
If you are interested in our moisture mapping services, please don’t hesitate to get in contact with our expert team. Have a look at our testimonials and case studies to see examples of our success stories with our valued clients. We offer a range of domestic services from moisture mapping to smoke damage restoration.
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| 0.996416 |
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