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aries1988 : example   32

Using CFD to Help Increase the Safety of Driverless Cars
Pointwise uses a multiple block approach simplifying complex CFD studies into modular grids that can easily be linked together. This approach gives users full control of the process, from the smallest element to the largest, and enables them to troubleshoot and improve grid quality early in the process. It also saves time and increases accuracy by allowing the reuse of grids in different configurations for additional CFD studies.

“For the motorway study, I did not have to re-mesh the car. I did not have to re-extrude viscous layers or re-mesh the volume,“ says Khalil. “It saves a remarkable amount of time and ensures that the results are exactly the same because we’re using the exact same data and mesh. Pointwise’s T-Rex feature was also critical to accurately capturing the boundary layer flow, which is especially important for turbulence studies.”
cfd  example  driving  automation  car  autoroute 
25 days ago by aries1988
Case Study: CFD and AI Can Aid Driverless Cars | Another Fine Mesh
Working with his professors and advisors, Khalil began by gathering data about road conditions on the UK’s M1 roadway such as traffic patterns, accidents, winds, and speed. He then used Pointwise to create individual high-fidelity meshes for the subject car and a variety of vehicles. After inputting the road conditions and running simulations on the individual aerodynamics of the main vehicle, he joined all the meshes together using Pointwise’s multiple block feature for the final study of how the moving parts interacted together.
cfd  example  driving  automation 
25 days ago by aries1988
Atrocities. Norms. Bicycles. See Where We’re Going With This?
But he didn’t do it alone. An entire team culture enabled Mr. Armstrong and his fellow riders to dope themselves to peak performance. The team’s doctor, its support workers, even riders’ wives were all enlisted to support and cover up the drug regimen. Team members from that time describe doping as a joint effort, something everyone approached with the same dedication and care that they applied to the rest of their training.

The pervasive doping, on that team and others, endangered riders’ health. It ruined lives. But if you read accounts by people who were involved, the most striking thing is that doping didn’t feel bad to them at the time. It felt more like a responsibility; one more thing that the team was doing to reach their ultimate goal of victory — and that everyone needed to help with.

Everyone on Lance Armstrong’s team knew that performance-enhancing drugs were banned in cycling. But those weren’t the rules that mattered. The internal rules, the norms for how people should behave to be a good member of the team, were the ones that held sway. And those norms said: Good members of this team do whatever it takes to win, so take the drugs.

In fact, even if you do know that your group is wrong, independence is still painful. In a 2005 study, fMRI scans of people contradicting their group’s statements showed increased activity in the part of the brain that processes emotional distress and fear, even when the subjects knew they were giving the correct answer to an easy question.

Those incentives, left unchecked, will shape group norms; those norms, in turn, will demand conformity. Participation in horrifying acts can become a condition of membership in good standing.
social  norm  concept  morality  population  example  explained 
10 weeks ago by aries1988
This Is How I Thread (Parallelism & Pointwise) | Another Fine Mesh
If parallelism is a tool, then that implies it is used to build something. What is that something? Put simply, optimized software. More specifically, parallelism is used to help computers solve bigger problems in less time. However, parallelism is not the only technique used to optimize code.

In the computing world, one name we give our workers is threads (short for threads of execution). When multiple threads are used in conjunction to solve a problem, this is called multithreading. If a problem can be subdivided so that multiple threads may execute concurrently to accomplish the same goal, then less time will be required to finish. However, subdividing problems is not always straightforward.

Fortunately, the algorithms used for many of the examine metrics in Pointwise fall into the “embarrassingly parallel” category.
So, what does it mean for an algorithm to be “embarrassingly parallel”? Simply put, it means that very little effort is required to divvy up a problem into parallel tasks. On top of this, little or no communication or synchronization among threads is required. Raw information is provided to each thread and each thread processes that data independently.
Unfortunately, cases like this are the exception. Data is rarely in such an amenable format, and threads often need to be highly interdependent to arrive at a solution.

However, closer inspection reveals that simply dividing the point data between threads for multithreaded execution will not provide sufficient isolation. This is because the algorithm requires that incident element data remain constant while a point is being positioned. If one thread modifies any point on a hull that another thread is manipulating, then results become inconsistent at best and corrupt at worst. The likelihood of such a scenario occurring increases dramatically as the number of threads increases.

Such organization can be achieved through the use of mesh partitioning. If the input mesh may be reliably and consistently partitioned into contiguous chunks, then each thread would be free to operate on its own chunk without fear of interfering with a concurrent thread.
The solution we adopted for this problem is to create a new, non-contiguous partition that only includes boundary points. This partition is then processed serially after multithreaded execution.

Of course, mesh partitioning presents overhead that a serial implementation
explained  parallelism  example  mesh  tool 
10 weeks ago by aries1988
大山侃大山:北京人讲不了广东话
SONY CENTRE FOR THE PERFORMING ARTS Dashan Live - Beijingers Can't Speak Cantonese 1,338 views Dashan 大山 Published on Feb 15, 2019 February 4, 2019 at the Sony…
canton  accent  fun  humor  video  chinese  beijing  example  language 
february 2019 by aries1988
Turbulence, the oldest unsolved problem in physics

because our understanding of turbulence over time has stayed largely ad-hoc and limited, the development of technology that interacts significantly with fluid flows has long been forced to be conservative and incremental. If only we became masters of this ubiquitous phenomenon of nature, these technologies might be free to evolve in more imaginative directions.

Motions of fluids are usually hidden to the senses except at the interface between fluids that have different optical properties.

For example, you can see the swirls and eddies on the surface of a flowing creek but not the patterns of motion beneath the surface.

The Navier-Stokes equation is difficult to solve because it is nonlinear. This word is thrown around quite a bit, but here it means something specific. You can build up a complicated solution to a linear equation by adding up many simple solutions. An example you may be aware of is sound: the equation for sound waves is linear, so you can build up a complex sound by adding together many simple sounds of different frequencies (harmonics). Elementary quantum mechanics is also linear; the Schrödinger equation allows you to add together solutions to find a new solution.

The idea is that the interesting dynamics occur at larger scales, and grid points are placed to cover these. But the subgrid motions that happen between the gridpoints mainly just dissipate energy, or turn motion into heat, so don’t need to be tracked in detail. This approach is also called large-eddy simulation (LES), the term eddy standing in for a flow feature at a particular length scale.

The idea is that, while the low-speed solution is valid at any speed, near a critical speed another solution also becomes valid, and nature prefers that second, more complex solution. In other words, the simple solution has become unstable and is replaced by a second one. As the speed is ramped up further, each solution gives way to a more complicated one, until we arrive at the chaotic flow we call turbulence.
turbulence  Physics  science  history  explained  example  LES 
december 2018 by aries1988
一周看完 3 本书,怎样读才能真正吸收?| 有用功 | 爱范儿

曾经高亮过的关键词和语句,都被做成了「小卡片」的形式,放在了大纲和思维导图里,等你来把它们重新组织起来。

这正是 MarginNote 令人着迷的地方:

所有你标记过的文字,插入过的批注,都会被「剪藏」到一个笔记本,作为备用的笔记素材收集起来;
这些笔记可以在页边、大纲列表、思维导图、学习卡集中不同的视图里自由切换;
笔记和大纲、思维导图是联动的,你可以边对照原文修改笔记,边在大纲或思维导图里重组笔记架构。
marginnote  example  book  reading 
july 2018 by aries1988
Sig WindE/Validation Cases - OpenFOAMWiki
The aim of this page is to hold validation cases for ABL (Atmospheric Boundary Layer) flows that are of interest to anybody starting to model ABL flows in OF. The simulations I perform, and refer to mainly in this text are RANS with k-epsilon turbulence closure models, using simpleFoam. Most of the first simulations that are placed in this page were done according to the excellent Martinez 2011 Ms.C. thesis [1] All of the boundary conditions and mesh creation suggestions were followed by from his work and the references within it.
validation  example  tool  data  ofm 
october 2017 by aries1988
Analysis | We have a pretty good idea of when humans will go extinct

That radical notion — that we are not, in fact, at the center of the universe — gives rise to what modern scientists call the Copernican Principle: We are not privileged observers of the world around us. We don't occupy a unique place in the universe. We are profoundly ordinary. We are not special.

Assuming that you and I are not so special as to be born at either the dawn of a very long-lasting human civilization or the twilight years of a short-lived one, we can apply Gott's 95 percent confidence formula to arrive at an estimate of when the human race will go extinct: between 5,100 and 7.8 million years from now.
probability  fun  example  human  disaster  berlin  future  prediction  earth  question 
october 2017 by aries1988
Calcul d'intérêts des livrets d'épargne
Les livrets d'épargne comme le Livret A, le Livret Bleu du Crédit Mutuel, le Codevi, et plus généralement les livrets d'épargne à taux réglementés ont un calcul d'intérêts par quinzaine.
explained  finance  numbers  example  bank 
september 2017 by aries1988
D.I.Y. Artificial Intelligence Comes to a Japanese Family Farm
The Koikes have been growing cucumbers in Kosai, a town wedged between the Pacific Ocean and the brackish Lake Hamana, for nearly fifty years.

For his project, he used TensorFlow, which Google released to the public in 2015.

He began by building a custom photo stand, which allowed him to photograph each cucumber from three angles. Then, to analyze the images, he adapted a popular piece of TensorFlow software used for recognizing handwritten numerals. Before he could turn the A.I. loose, though, Koike had to train it. He captured seven thousand photos of cucumbers that his mother had already sorted, then used the data to teach his software to recognize which vegetables belonged in which categories. Finally, he built an automated conveyor-belt system to move each cucumber from the photo stand to the bin designated by the program.
agriculture  ai  business  city  countryside  engineering  example  family  japanese  story 
august 2017 by aries1988
python - Remove a tag using BeautifulSoup but keep its contents - Stack Overflow
html = "<p>Good, <b>bad</b>, and <i>ug<b>l</b><u>y</u></i></p>"
invalid_tags = ['b', 'i', 'u']
print strip_tags(html, invalid_tags)
The result is:

<p>Good, bad, and ugly</p>
beautifulsoup  calibre  example 
march 2013 by aries1988
version control - Detect the OS from a Bash script - Stack Overflow
platform='unknown'
unamestr=`uname`
if [[ "$unamestr" == 'Linux' ]]; then
platform='linux'
elif [[ "$unamestr" == 'FreeBSD' ]]; then
platform='freebsd'
fi
os  bash  example 
march 2013 by aries1988
Python 正则式学习笔记 - whycadi的专栏 - 博客频道 - CSDN.NET
‘*?’ ‘+?’ ‘??’ 最小匹配
‘*’ ‘+’ ‘?’通常都是尽可能多的匹配字符。有时候我们希望它尽可能少的匹配。比如一个c语言的注释 ‘/* part 1 */ /* part 2 */’,如果使用最大规则:
>>> s =r ‘/* part 1 */ code /* part 2 */’
>>> re.findall( r’/*.**/’ , s )
[‘/* part 1 */ code /* part 2 */’]
结果把整个字符串都包括进去了。如果把规则改写成
>>> re.findall( r’/*.*?*/’ , s )                    #在*后面加上?,表示尽可能少的匹配
['/* part 1 */', '/* part 2 */']
结果正确的匹配出了注释里的内容
python  example  learn  pattern 
march 2013 by aries1988
Adding your favorite news website — calibre User Manual
Remove articles in feeds based on a string in the article title or url.
calibre  ebook  kindle  news  rss  learn  explained  example 
march 2013 by aries1988
OCR - Extract Scanned Text From PDF
#!/bin/bash
# - ocrpdf - Extract scanned text from a PDF file using Tesseract,
# Poppler and ImageMagick.
# Check if all necessary executables are installed
# Check if exist the file and is a pdf
# People that use graphical file managers happily use names like
# "This is my file.pdf" and include brackets, commas, non ascii
# symbols. And in some cases slashes too! Then they send this file
# like an email attachment and it travels across different machines
# and programs, protocols, encodings, character sets, etc. Despite
# most today operating systems and programs are able to get rid of
# this, it is not a good practice.
#
# Cleaning some weird symbols from file's name
# Convert pdf to ppm images
# Convert PPM images to TIF. If you use TIFF (two efs) tesseract
# returns an error
# Convert tif images to plain text
# Join txt files
# End ocrpdf
filename  example  bash 
september 2012 by aries1988
Extract Scanned Text From PDF
Extract scanned text from a PDF file using Tesseract, Poppler and ImageMagick.
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Advice about the scripts included in this site: try to understand what the script does and attempt to write your own version. If you just cut and paste the next time you'll have to visit my stupid site again ;-). Remember, it's not free software but to learn what makes you free.
bash  example  filename  pdf  oct  linux  howto  script 
may 2012 by aries1988

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