h********r
发帖数: 519 | 1 When I was eighteen I wanted to be … a mechanical engineer.
The biggest challenge facing scientists is … nonlinearity.
I am waiting for the day when someone will discover … a hybrid of a plant a
nd an animal that can create its own energy by photosynthesis and move aroun
d.
Young people should study chemistry because … it is the foundation for stud
ying other subjects in science, engineering, and medicine.
Looking back over my career, I … would like to say “thanks” to those who
have said “no” to... 阅读全帖 |
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q***l
发帖数: 177 | 3 National Academy of Engineering Elects 66 Members and 10 Foreign Associates
WASHINGTON — The National Academy of Engineering (NAE) has elected 66 new
members and 10 foreign associates, announced NAE President Charles M. Vest
today. This brings the total U.S. membership to 2,254 and the number of
foreign associates to 206.
Election to the National Academy of Engineering is among the highest
professional distinctions accorded to an engineer. Academy membership
honors those who have made outstand... 阅读全帖 |
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s********n
发帖数: 235 | 4 Title: THE POSSIBLE USE OF MIXED IONIC ELECTRONIC CONDUCTORS INSTEAD OF
ELECTROLYTES IN FUEL-CELLS
Author(s): RIESS I
Source: SOLID STATE IONICS Volume: 52 Issue: 1-3 Pages: 127-134 DOI:
10.1016/0167-2738(92)90098-A Published: MAY 1992
Title: A NONLINEAR LEAST-SQUARES FIT PROCEDURE FOR ANALYSIS OF IMMITTANCE
DATA OF ELECTROCHEMICAL SYSTEMS
Author(s): BOUKAMP BA
Source: SOLID STATE IONICS Volume: 20 Issue: 1 Pages: 31-44 DOI: 10.
1016/0167-2738(86)90031-7 Published: FEB 1986
Tit... 阅读全帖 |
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s********n
发帖数: 235 | 5 Title: PLAUSIBLE CONCEPTS NECESSARY AND SUFFICIENT FOR INTERPRETATION OF
CERAMIC GRAIN-BOUNDARY PHENOMENA .1. GRAIN-BOUNDARY CHARACTERISTICS,
STRUCTURE, AND ELECTROSTATIC POTENTIAL
Author(s): KINGERY WD
Source: JOURNAL OF THE AMERICAN CERAMIC SOCIETY Volume: 57 Issue: 1
Pages: 1-8 DOI: 10.1111/j.1151-2916.1974.tb11350.x Published: 1974
Title: PLAUSIBLE CONCEPTS NECESSARY AND SUFFICIENT FOR INTERPRETATION OF
CERAMIC GRAIN-BOUNDARY PHENOMENA-II, SOLUTE SEGREGATION, GRAIN-BOUNDARY
DIFFUSIO... 阅读全帖 |
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C*****G
发帖数: 81 | 6 Title: A NONLINEAR LEAST-SQUARES FIT PROCEDURE FOR ANALYSIS OF IMMITTANCE
DATA OF ELECTROCHEMICAL SYSTEMS
Author(s): BOUKAMP, BA
Source: SOLID STATE IONICS Volume: 20 Issue: 1 Pages: 31-44 DOI: 10.
1016/0167-2738(86)90031-7 Published: FEB 1986
many thanks!
x********[email protected] |
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d*******7
发帖数: 188 | 7 need the following two papers, baozi x2, thanks for the help.
[1]
Title: On-line Inspection for Glass Fiber Forming,
Journal: ASME Journal of Manufacturing Science and Engineering, 2007,
Author: *Paul P. Lin, Qin Guo, Xiaolong Li
Link: http://manufacturingscience.asmedigitalcollection.asme.org/mobile/article.aspx?articleid=1450868
[2]
Title: Intelligent Fault Diagnosis, Prognosis and Self-Reconfiguration for
nonlinear Dynamic Systems Using Soft Computing Techniques,
Journal: IEEE Conference, 200... 阅读全帖 |
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g****g
发帖数: 8 | 8 Position for
Ph.D graduate student for
• Optical super resolution nanoscopy,
• Micro/nanofluidics,
• Bioimaging
Highly motivated applicants with strong experimental background in optics
and bioimagings or micro/nanofluidics are invited to apply for Ph.D student
position for experimental research in Biomedical Engineering. We have
developed a large multifunctional far-field optical nanoscopic system using
two tunable femto lasers for the super resolution imaging,
nanop... 阅读全帖 |
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f*********e
发帖数: 211 | 9 I want to be a structural analysist either in dynamics or statics. I can do
nonlinear dynamical analysis. |
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y****a
发帖数: 172 | 10 来自主题: CivilEngineering版 - 提供点信息 要看那方面。按规范设计，包括equivalent lateral force, response spectrum和
linear time history，现在基本没有多大难度了。nonlinear和nolinear control还不
是人人都能做。 |
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g******6
发帖数: 782 | 11 http://www.nae.edu/56154.aspx
National Academy of Engineering Elects 66 Members and 10 Foreign Associates
WASHINGTON — The National Academy of Engineering (NAE) has elected 66 new
members and 10 foreign associates, announced NAE President Charles M. Vest
today. This brings the total U.S. membership to 2,254 and the number of
foreign associates to 206.
Election to the National Academy of Engineering is among the highest
professional distinctions accorded to an engineer. Academy membership
honor... 阅读全帖 |
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h*****q
发帖数: 58 | 12 From all the posts above,I guess my best choice is still private company,
maybe internal transfer for me is best for me.
Just to clarify my modeling/analysis experience is all kinda "not-easy"
stuff.
From suspension, cablestayed bridges, to regular thru-arch truss , and from
static to dynamic, linear to nonlinear, stage to impact loading, time
history, plastic hinge, you name it. I am sick of these kinda of stuff.
So i guess all my experience for DOT people are useless. Right?
$h!t |
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p***8
发帖数: 36 | 13 PhD and post-doc positions in Mechanical Engineering are immediately
available in the research group of Dr. Yi Wang at the University of South
Carolina-USC (Columbia/Main campus, https://www.sc.edu/study/colleges_
schools/engineering_and_computing/faculty-staff/yi_wang.php). USC is the
flagship university in the State of South Carolina, and the Ph.D. program at
the department of Mechanical Engineering is ranked No. 31 nationally by the
National Research Council (NRC) [1], and the College of Engi... 阅读全帖 |
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p***8
发帖数: 36 | 14 PhD positions in Mechanical Engineering are immediately available in the
research group of Dr. Yi Wang at the University of South Carolina-USC (
Columbia/Main campus, https://www.sc.edu/study/colleges_schools/engineering_
and_computing/faculty-staff/yi_wang.php). USC is the flagship university in
the State of South Carolina, and the Ph.D. program at the department of
Mechanical Engineering is ranked No. 31 nationally by the National Research
Council (NRC) [1], and the College of Engineering and ... 阅读全帖 |
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b*****y
发帖数: 163 | 15 if you mean elasticity, then the book below
is a good reference:
Foundations of the Nonlinear Theory of Elasticity
by V.V. Novozhilov |
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s*****l
发帖数: 167 | 16 What kind of computational problems are you dealing with in solid mechanics?
solving nonlinear elasticity eqns? |
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bd
发帖数: 21 | 17 dynamic crack problems and some nonlinear problems. |
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s*****l
发帖数: 167 | 18 I need some reference in elasticity (better be nonlinear).
Basically, I need some examples where the solution is more or less known,
quantitatively or qualitatively.
I want to test a numerical procedure. But I have to have a way to
verify my numerical solution. The example has better be a 3D problem but
can be reduced to one dimensional solution. Also if there is heat transfer
it is better.
If you know of any paper or book that has these kind of
examples, please let me know.
Thanks! |
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s*s
发帖数: 6 | 19
This is a typical problem that can be solved by using the shooting method. The
shooting method is a commonly-used method in numerical solution of nonlinear
dynamical differential equations. Just look up this method in mechnical or
applied mathematical journals. Good luck. |
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c*******e
发帖数: 8624 | 20 如果你说解非线性方程组的话,都改成一阶的,然后用ode solver就可以了 |
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P****S
发帖数: 2286 | 21
'fsolve' in Optimization toolbox. |
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f****e
发帖数: 15 | 22
: ~~~~~~~~~
no ba, he meant to solve algebraic equation.
i don't think matlab can solve every arbitrary algebraic equation. |
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x**u
发帖数: 21 | 23 hi, there
I'm now doing dynamic loading on a cube with a centeral hole. The
hole is filled with another material. I guess this should be a
nonlinear dynamics case so I used the implicit direct integration
for the analysis step. The step time is 0.5sec. The maximum
increments is 100. The following is definition in the keywords:
** ----------------------------------------------------------------
**
** STEP: Dynamical loading
**
*Step, name="Dynamical loading"
Dynamicl loading applied at the top su |
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t**********a
发帖数: 7 | 24 multivariate nonlinear regression
其中，非线性模型的形式由用户指定。必须用matlab等大软件吗？
没有用过matlab,敬请大虾们指点。多谢。 |
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o****p
发帖数: 7 | 25 现在的课题与uncertainty analysis有关，
面对的是一个 discontinuous, nonlinear 的complicated model （discrete in time
的 差分方程组），input, parameter很多，且uncertain。
我想问一下，除了Monte Carlo simulation之类的sampling
的方法之外，有没有其他的direct的方法来进行uncertainty analysis? 也就是说，在知
道inputs,parameters的 distribution（连续或者离散） 或者moments的情况下,如何得
到output的distribution 或者momens。
monte carlo太费时间了，对于我的问题的实际应用意义不大，所以我想有没有其他的方
法。 如果是一个differential equation,我倒是见过用expansion的方法解决的。
本人数学背景不强，在自己的领域内也没有看到相关研究，望哪位大虾能指点迷津。
谢谢 |
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o*****s
发帖数: 1445 | 26 I have a code like the following. But it is a linear constrained optimization
code. I want to solve nonlinear optimization. How can I change it? I knew
fmincon in matlab. Thanks a lot.
% [xmin,lambdamin,fxmin]=dnewtonlip('f','g',A,b,x0,tol)
%
% Given a function 'f', its gradient 'g', a feasible x0, and
% linear inequality constraints Ax>=b, use a discrete Newton method
% to minimize f, ending at a point xk, with
%
% |f(xk)-f(xk-1)| < tol*(1+|f(xk)|)
%
function [xmin,lambdamin,fxmin]=dn |
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i******d
发帖数: 4 | 27 I was trying use matlab to slove a complicated system of nonlinear algebraic
equation by function Solve. But it shows explicite solutions couldn't be
found. (for some parameters,it gives me solution in 5 minutes.but if i change
the parameter, it may takes forever for matlab or no explicit solution)
my equations are below. Unknowns are x, y and z, others are parameters.
Ssmith=solve('R*g*S*y/x^3-a*(1+0.5*R*g*y/x^3)/(b+R*g*y/x^3)-alpha*z/x^2=0',...
'0.0016*(647.68*z-1)*h0*x/(1+0.0024*(647.68*z |
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a*******o
发帖数: 129 | 28 【 以下文字转载自 CS 讨论区,原文如下 】
发信人: ayiyahiho (sddddddddddddddddd), 信区: CS
标 题: lineariation problem....help, please
发信站: Unknown Space - 未名空间 (Mon Jun 6 17:52:27 2005) WWW-POST
Hi, all,
I have a nonlinear constraint which i don't know how to linearize it.
it is in the form
x*y=z
x and y both have a bound.
Then, how can i linearize it? I hope I can achieve a LP or MILP form by
linearization.
Thank you very much. |
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m********e
发帖数: 5088 | 29 现在急需解一个stationary nonlinear schrodinger equation:
-U''+q*U^3=EU （3D)
这个U就是wave function，是在complex space里面的, E是eigen
energy。本来想用femlab解的，结果发现它是白痴。
大家有没有比较好的数值解方法阿？ |
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m********e
发帖数: 5088 | 30 Femlab会自动地把nonlinear
part忽略的，我已经试过了。对于eigenvalue问题，famlab好像只能解linear problem。
当然，我也用的不熟，你觉得应该怎么解？ |
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Y********x
发帖数: 322 | 31 it is highly nonlinear and need to be described by a separate
function. maybe I have to resort to other more powerful solver. Anybody know
s other BIP solver i can try? Thanks a bunch!
ab
funct |
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s**i
发帖数: 381 | 32 no. Everything in turbulence is deterministic by nature. it is just the
nonlinearity makes it look like "random".
The so-called nonclosed terms come after the averaging, but that is called
the
RANS model, no longer N-S any more. |
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c****1
发帖数: 5654 | 33 i used to a PhD candidate at Math dept. majoring scientific computing,
learned
a lot about numerical analysis, PDE, ODE, linear/nonlinear programming, etc..
i wonder how easy it is to use to knowledge plus my 5 years software
experience
thanks a lot!
i found my current job(including previous one) as a software engineer does
not
need math background at all, i love to find a job using both software and
math
background, any idea? |
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r****y
发帖数: 1437 | 36 since you do not have a nonlinear term here, just spectral method.
of course, up to your domain and b.c., hehe. |
|
w**d
发帖数: 2334 | 37 Can someone help me download this paper? Our university doesn't have the
subscription.
Thanks alot. My email: c********[email protected]
Title: Resolution of a stochastic weakly damped nonlinear Schrodinger
equation by a multilevel numerical
method
Author(s): Moebs G, Temam R
Source: JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND
VISION 17 (10): 1870-1879 OCT
2000 |
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j**u
发帖数: 6059 | 38 ☆─────────────────────────────────────☆
whatsmore (kick) 于 (Thu Jun 28 14:27:34 2007) 提到:
用过matlab的optimization tool box.不是很好用。
☆─────────────────────────────────────☆
windwin (chaos) 于 (Thu Jun 28 14:49:52 2007) 提到:
TOMLAB?
☆─────────────────────────────────────☆
SCM (SCM) 于 (Thu Jun 28 14:52:31 2007) 提到:
matlab does not work well for large scale problem
☆─────────────────────────────────────☆
longhei ($$$$$$$$$$$$) 于 (Thu Jun 28 16:48:46 2007) 提到:
knitro :-)
☆───────────── |
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s****h
发帖数: 921 | 39 x=[x1,x2,...,xn]
min g(x)
st. f1(x)=0
f2(x)=0
...
fm(x)=0
传统算法是Least Square加Gauss-Newton法迭代作.
但当x维数很大的时候,收敛性有一些问题.
但是我的问题有一个特殊之处:
迭代计算,
每次将f(x)从nonlinear方程变成linear方程,h(x).
h(x)和f(x)关系类似h(x)=f(x)/x
这样每次就可以用Least Square解线性方程算出x.
每次再重新迭代.
我发现有趣的是收敛性能更好了.
但是迭代步数增加了.
我感觉有点象Gaussian-Siedel和Newton-Raphson解非线性方程.
前者收敛性能好像好一点,主要对初值要求不高,但收敛步数的确比Newton-Raphson多.
当然,二个算法都没保证一定会收敛. |
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S*M
发帖数: 536 | 40 check coin-or
for open source solver for nonlinear programming, I suggest IPOPT, which is
included in coin-or |
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k*******n
发帖数: 116 | 41 我的PDE model是 2D nonlinear incompressible elasticity
具体的set up是一块正方形的neo-Hookean材料，左边固定，右边用一个力拉
因为是个非线性问题，我用最简单的牛顿法迭代
得到的算法是收敛的，画出的displacement和pressure的图也是符合物理直观的
可是我怎么知道这个解是可靠的呢？
因为我以前就有过惨痛的教训，算法看起来收敛，图也和物理直观相符，但其实是错误的
所以我想知道有个简单易行的办法可以验证数值解的可靠性 |
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l*****i
发帖数: 3929 | 42 lsqcurvefit - Solve nonlinear curve-fitting (data-fitting) problems in least
-squares sense
Equation
Find coefficients x that best fit the equation
given input data xdata, and the observed output ydata, where xdata and ydata
are matrices or vectors of length m, and F (x, xdata) is a matrix-valued or
vector-valued function.
The lsqcurvefit function uses the same algorithm as lsqnonlin, and provides
an interface designed specifically for data-fitting problems.
Syntax
x = lsqcurvefit(fun,x0,xdata,y |
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n******8
发帖数: 172 | 43 isn't it a 2-D nonlinear fitting? |
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L*******g
发帖数: 913 | 44 2D的error minimization可以自己写一个吧。没做过，我猜的。 |
|
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f********a
发帖数: 15 | 46 我是想phd以后弄个master，但不是biomath master。是类似于应用数学的master，很
多课程都是pde，numerical methods， finite element methods，functional
analysis之类的课程，还有一些具体的modelling的课程，比如Mathematical Ecology
and Biology，Stochastic Differential Equations，Fluid Mechanics，Nonlinear
Systems，Statistical Mechanics等等。当然还有编程的课程，c＋＋， matlab。
你说的很对，他们都很需要和experimentalists合作，他们做modelling需要我们的数
据。我说的他们不欢迎我们的意思是到具体做modelling的时候，他们就不欢迎我们啦
，当然这也可以理解，毕竟我们学生物的多数都不学数学，也很少用到数学。 |
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f*****n
发帖数: 72 | 47 在解一个nonlinear optimization的问题，variables有441个. 开始3步是可以到2nd
order的，但是后面就会收敛很慢，基本上Gradient的norm就是常数了，老板让我找个
解释出来。。。想了半天无果。
code写的应该是没有问题的，因为有一个intial condition是可以得到2nd order
converge的，但是除此自外都不行，这也是一个需要解释的地方
输出如下：
Iter f(x) norm of grad
1 1.338356896477270 15.817786428955722
2 0.058318467536695 1.454325027881377
3 0.016906651903142 0.312036346047469
4 0.017479034846915 0.034953665750925
5 0.017480904458215 0.031569943654202
6 0.017484810226725 |
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f***e
发帖数: 43 | 48 一个目标函数，有10来个参数。求最值的那种。。。
函数应该比较规则，没有奇点，不过gradient如果需要得numerical，
关键在于10来个，numerical graident也蛮麻烦。
参数有些范围的constraint,
可能还有些别的nonlinear constraint |
|
k*********g
发帖数: 791 | 49 这几天我一直忙着做网站。就你关于sem的评论说一下。
Discontinuous的目的好处：
1 flux control，这样有利于local conservation
2 有利于并行计算
DG, discontinuous galerkin, 在计算固体力学领域经常成为 DG FEM 的代名词，但是
，有限元做成 discontinuous 是没有太多意义的，性能提高很少，却麻烦了很多。为
啥，我有点忘了为啥，但这是我几年前下的结论。如果真的要用有限元，还是
classical的continuous finite element method性价比高。
在scientific computing领域，galerkin的定义比较混乱，经常这一波人说的galerkin
和那一波人说的galerkin不是同一个意思。我认为，galerkin这么定义比较canonical
：用best fitting方式、主体在transform space计算的称之为galerkin。
这个定义是照顾了spectral method community的习惯，有点anti有限元的，因为在有
限元，g... 阅读全帖 |
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j****x
发帖数: 943 | 50 来自主题: Computation版 - 并行计算 gpu如果要不同的multiprocessor之间传递数据，那就是一出悲剧。所以对nonlinear的
problem，一个gpu没有多大提高，除非你有n个gpu，那还不是要用mpi，不知道nvidia
的infiniband搞定了没。 |
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