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Some questions about wave propagation

Submitted by LG on

Dear Sir,

As we know, periodic signals are best analysed in the frequency domain while stochastic signals are usually more profitably analysed in the time domain. The analysis in the frequency domain usually concern only one signal while in the time domain often involves the comparison of several different signals.

1) what are the general methods for transforming the frequency domain into time domain, and which should be superior?

Isotropic hardening and kinematic hardening

Submitted by kajalschopra on

I've been trying to figure out difference between isotropic and kinematic hardening.

As I see,kinematic hardening can model reversible nbehaviour of metals (Bauschinger effect).

In isotropic hardening, the yield surface increase in size, but remain the same shape, as a result of plastic straining.

That is, if the yield surface is represented by a cylinder of radius "A" then an increase in the radius denotes an increase in the yield stress as a result of plastic straining.

A Problem in Nature Of XFEM Approximation

Submitted by S. Omid R. Biabanaki on

There is a basic problem in NATURE of approximation of discontinuity in element using XFEM.I tried to illustrate that below:

for example, If you consider an element with strong discontinuity( like fracture or contact) which usually we use heaviside function as enrichment function. we expect two parts of element deform independently because of nature of problem.



In equation for approximation of this element we have two main parts. First  is 'regular' or 'standard' part which uses the standard shape functions of element and Second is the enriched part.

Faculty Position in Materials Science and Engineering at the University of Pennsylvania

Submitted by Dan Gianola on

The Department of Materials Science and Engineering at the University
of Pennsylvania
invites applications for a tenure track faculty
position
. Applications will be considered from outstanding candidates
in any emerging area of Materials Science and Engineering. Successful
candidates will be committed to excellence in undergraduate and
graduate teaching, in particular curriculum development related to

Mechanics connection to memory

Submitted by Taher A Saif on

Mechanical tension contributes to clustering of neurotransmitter vesicles at presynaptic terminals. 

Scott Siechen, Shengyuan Yang, Akira Chiba and Taher Saif

Proceedings of the National Academy of Sciences,   August 4, 2009   vol. 106   no. 31   12611–12616 

http://www.pnas.org/gca?gca=pnas%3B106%2F31%2F12611&allch= 

 

The Meaning of the Concept of Potential in Mechanics (and in Physics)

Submitted by Ajit R. Jadhav on

If someone knows of books/articles dealing with the meaning of the concept of potential in physics (or concerning the physical bases underlying the energy methods of mechanics) then I would very much appreciate getting to know about these.

Wondering about the Mechanics of Bacterial Death

Submitted by Ajit R. Jadhav on

0. I was idly thinking about the current H1N1 flue pandemic, and the following things occurred to me. Please note, I know very little about this subject matter. So, please consider descriptions in the following as, at best, tentative.



1. There is a basic difference between how alcohol kills viruses and how salt-water kills bacteria. [Alcohol is used in the hand-cleaners they use in hospitals. Girgling with salt-water is the first line of defense (and an unexpectedly highly effective one) which is well known for millenia.]



Fourth International Conference on Engineering Failure Analysis (ICEFA IV) - abstract deadline 27 November 2009

Submitted by Dan Lovegrove on

Following successful meetings in Lisbon, Toronto and Sitges, Elsevier will host the Fourth International Conference on Engineering Failure Analysis (www.icefa.elsevier.com) at Churchill College in Cambridge from the 4th - 7th July 2010. You are invited to participate in the latest in this important series of conferences, which have established a respected biennial forum for the discussion and dissemination of knowledge and experience in Engineering Failure Analysis.