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Interesting Conference: "micro-TAS 2006"

The conference "micro-TAS" may be interesting to researchers in engineering and science, especially involving Bio-MEMS/NEMS, biophysics, and biochemistry. See details of this conference.

Cellular and Molecular Mechanics

Cellular and Molecular Mechanics I was invited by Dr. Zhigang Suo to write a short piece on “Cellular and Molecular Mechanics”. I am writing this informally to introduce this subject matter rather than talk in vernacular such as mechanotransduction, phosphorylation, etc. I have more formal papers if someone is interested in more detailed discussions on this subject area. This is a field in which I have been working for over a decade now and I find it more exciting every day. The question always is how does mechanics affect biological processes. This is a very interdisciplinary subject matter as mechanists, engineers, physicists, chemists, and biologists have been investigating this process from various perspectives. I am obviously not the first to study this process. For most of us, it is realized from an empirical perspective that mechanics matters to biology, but exactly how mechanics specifically alters biochemistry continues to be highly debated today. Mechanics of course matters in many physiological areas. Your blood flows, your heart pumps, your bone and muscle feel mechanics. Not only does the body experience mechanical stimulation, but it reacts biochemically to it. A wonderful example is when people go into space (NASA) for long periods of time. The bone in one’s body begins to resorb in a similar response mode to what one experiences in aging (osteoporosis). This is primarily due to just the change in the gravity (mechanics). Other diseases are related to these issues including the two biggest killers: heart disease and cancer. While biomechanics on this scale has been studied for awhile (Leonardo Da Vinci, who was interested in mechanics, also wrote one of the first texts on anatomy), the movement to the cellular and molecular scales has brought a tremendous amount of excitement. I consider the cell as one of the ultimate smart materials exhibiting these characteristics. The cell has evolved over millions of years and is designed better than almost any system that we can personally build. Just as the biological eye provides a beautiful template for optics based lenses, much can be learned about building technology (“nanotechnology” and “microtechnology”) through examining the behavior of cells and molecules.

Zhigang Suo's picture

A Fresh Look at a Beautiful Subject

This is a review on Thermal Physics by Charles Kittle and Herbert Kroemer. I posted the review on Amazon on 2 December 2001.

This is by far THE BEST textbook on the subject. As many people say, thermodynamics is a subject that one has to learn at least three times. I can easily understand the very negative review from the undergraduate student at Berkely. The subject itself is hard, and simply is not for everyone, not for the first run at least. I say this from experience. I earned a Ph.D. degree over ten years ago, and took courses on thermodynamics at both undergraduate and graduate levels. I didn't understand the subject at all, and didn't find much use in my thesis work. However, something about the subject has kept me going back to it ever since. I now own about 40 books on the subject, and use the ideas almost daily in my research.

the FFT based algorithm to solve the continuum electrostatic field

In the paper[1], the continuum electrostatic simulation in the ion transport through membrane-spanning nanopores is realized by the implicit-solvent method. To solve the problem, the governing equation (Poisson equation for systems with heterogeneous permittivity) is expressed and the electric field is calculated in its reciprocal space by applying 3D-FFT[2]. The system is considered periodic, and a modified vacuum field outside is defined. The rectangular unit cell is discredited into grid points. By iteratively revise this modified vacuum field, the residual of the electric field at the grid points reach its minimum in the real space. After getting the predefined threshold, the iteration is terminated and the reaction potential is calculated. The potential at any point in the domain is interpolate by its eight surrounding grid points. The accuracy and convergence properties of this proposed algorithm are very well, with an overall speed comparable to a typical finite-difference solver.

Zhigang Suo's picture

Elements of linear elasticity

Update on 26 September 2008: An updated file on elements of linear elasticity is posted. You can still access the older version by clicking "revisions".

Return to the outline of the course.

The Fourth China-Japan-Korea Joint Symposium on Optimization of Structural and Mechanical Systems

The Fourth China-Japan-Korea Joint Symposium on Optimization of Structural and Mechanical Systems will be held in Kunming, China, November 6–9, 2006.

http://sail.dlut.edu.cn/cjkosm4/Home/Index.htm

Recent advances of computer technology have given powerful practical tools to structural and mechanical designs. Optimal design is one of such area where various theories and methodologies are well developed. It is, however, lacking general interests among field designers and engineers. Innovative optimal design techniques and new applications are yet to be developed. Following the successful first CJK-OSM1 in Xian, China in 1999, second (CJK-OSM2) in Busan, Korea in 2002 and the third (CJK-OSM3) in Kanazawa, Japan in 2004, as agreed among participants in the symposium, the fourth CJK-OSM symposium will be held in Kunming, China during Nov. 6th -Nov. 9th, 2006. As before this will be a forum for exchange of recent research ideas and fostering new developments and new applications. Reflecting current interests from various fields, several new topics are included. The scope is, however, not limited to those listed.

Symposium on Mechanics in Biology and Medicine

This symposium will be part of the 2007 ASME Applied Mechanics and Materials Conference, to be held in the University of Texas in Austin, in June 3-6, 2007.

Nanotube 'forest' makes super slippery surface

A material less sticky than Teflon has been created by covering a surface with a "forest" of carbon nanotubes. Newscients.com has a very interesting report. Read more...

Student Presentation Competition at USNCCM IX

The 9th US National Congress on Computational Mechanics will feature a student presentation competition. This competition continues in the format pursued at the recent World Congress in Los Angeles. It is open to students who have an abstract accepted for presentation at the Congress.

19th Annual Melosh Competition at ETH Zurich

The 19th Annual Melosh Competition for the Best Student Paper on Finite Element Analysis will be held at ETH Zurich, on April 27, 2007.    The competition has become one of the premier graduate student events in the broad area of mechanics.   We have held the competition at a variety of locations over the past several years, but this is the first time it will be held outside the US.  We are presently seeking funds to provide travel fellowships for those students selected as finalists, as this represents an excellent opportunity for students to visit a world-class institution.  

Details on the competition and submission procedure can be found here.   The extended abstracts are due on January 8, 2007. I want to emphasize that the competition is really one on computational science.   As a result, papers on meshfree methods, molecular dynamics methods, their coupling with the FEM, etc., are welcome.   Please encourage your colleagues working in computational science to consider applying.  

Pradeep Sharma's picture

Journal Club: Response/Feedback requested

Hello everyone,

I had previously posted this entry on the AMD blog and perhaps it worthwhile to post it again on this forum. I would like to solicit feedback and comments on an idea to further enhance the role and utility of iMechanica.

This inspiration comes from Bell labs and the physics community.....

They started a journal club (year 2003). Each month ONLY 2-3 already published recent journal papers are reviewed and commentary posted in the form of a newsletter. Since only 2-3 papers are reviewed, the selection is much more stringent and careful. The contribution is regular and periodic (monthly). Hence, this newsletter is taken seriously by physicists.

In our case, this can be done within iMechanica. I suspect we could achieve the same kind of interest if we restrict "notable" papers to 1-3 per month and make it a regular monthly feature. In principle anyone could submit a commentary but the blog moderators will select the top 2-3.

The operational rules are open for discussion. Briefly though, I am thinking on the lines of rotating 1-2 moderators with a term of say 2 months. The moderator will receive commentaries on recently published papers RELATED to mechanics area. The moderator will highlight 1-3 notable commentaries in the journal club newsletter. A key requirement must be that the commentaries/paper highlighted are related to mechanics in some form or the other. The concept of rotating moderator is to provide breadth and prevent bias of any one individual. Rotation of journal club moderators will also keep the "work-load" well distributed.

Pradeep Sharma's picture

Collected Works of J.D. Eshelby

Perhaps a post has already been made in this regard; A book containing all the papers by J.D. Eshelby was recently released by Springer. This book is compiled by Markenscoff and Gupta. Congratulations to both of them for such a great idea!

I bought this book last week and it is fascinating to read all of Eshelby's papers in chronological order. Furthermore, I found a few papers that I had not even been aware of. The price, at roughly $195 on Amazon is a bit steep but (in my opinion) well worth it. The book also contains forewords by several researcher who knew Eshelby personally.

Here is the amazon link to this book

Ting Zhu's picture

Handbook of Materials Modeling

by S. Yip (Editor), 2005

Book Review
"A new guide to materials modeling largely succeeds in its aim to be the defining reference for the field of computational materials science and represents a huge undertaking..." -- by James Elliott | University of Cambridge, Materials Today, Volume 9, Issues 7-8, July-Aug 2006, Pages 51-52.

Book Description
The first reference of its kind in the rapidly emerging field of computational approachs to materials research, this is a compendium of perspective-providing and topical articles written to inform students and non-specialists of the current status and capabilities of modelling and simulation. From the standpoint of methodology, the development follows a multiscale approach with emphasis on electronic-structure, atomistic, and mesoscale methods, as well as mathematical analysis and rate processes. Basic models are treated across traditional disciplines, not only in the discussion of methods but also in chapters on crystal defects, microstructure, fluids, polymers and soft matter. Written by authors who are actively participating in the current development, this collection of 150 articles has the breadth and depth to be a major contributor toward defining the field of computational materials. In addition, there are 40 commentaries by highly respected researchers, presenting various views that should interest the future generations of the community. Subject Editors: Martin Bazant, MIT; Bruce Boghosian, Tufts University; Richard Catlow, Royal Institution; Long-Qing Chen, Pennsylvania State University; William Curtin, Brown University; Tomas Diaz de la Rubia, Lawrence Livermore National Laboratory; Nicolas Hadjiconstantinou, MIT; Mark F. Horstemeyer, Mississippi State University; Efthimios Kaxiras, Harvard University; L. Mahadevan, Harvard University; Dimitrios Maroudas, University of Massachusetts; Nicola Marzari, MIT; Horia Metiu, University of California Santa Barbara; Gregory C. Rutledge, MIT; David J. Srolovitz, Princeton University; Bernhardt L. Trout, MIT; Dieter Wolf, Argonne National Laboratory.

Egon Orowan

August 2, 1901 - August 3, 1989

Question about dislocation nucleation sites in strained silicon-on-insulator

Electronic active device is built on the strained silicon-on-insulator (sSOI), e.g. strained Si layer on oxide, which in turn is bonded on bulk silicon wafer. Because no misfit dislocation can exist in strained silicon layer any more, will the dislocation be generated during later processing and operation? If there are still lots of dislocations in the strained silicon layer, where do they come from? Is there any experimental work to discover the dislocation nucleation sites? I guess they will nucleate from the triple junctions of gate-sSOI-cap, because the stress is singular in the triple junction. But I am not sure. So I want to know something about the experimental observations.

Ravi-Chandar's picture

McMat 2007 Applied Mechanics and Materials Conference

The McMat 2007 conference, organized by the University of Texas on behalf of the Applied Mechanics and the Materials Divisions of the ASME, will be held in Austin, June 3-7, 2007.

We are now accepting proposals for symposia and abstracts of papers.

My research work

I use this blog entry to upload my research work, then I have links for my publications in my resume. Otherwise, I don't have any links for my preprints.

If people can upload any files without writing a blog entry, that will be great.

Saturated voids in interconnect lines due to thermal strains and electromigration

Zhen Zhang, Zhigang Suo, Jun He

Thermal strains and electromigration can cause voids to grow in conductor lines on semiconductor chips. This long-standing failure mode is exacerbated by the recent introduction of low-permittivity dielectrics. We describe a method to calculate the volume of a saturated void (VSV), attained in a steady state when each point in a conductor line is in a state of hydrostatic pressure, and the gradient of the pressure along the conductor line balances the electron wind. We show that the VSV will either increase or decrease when the coefficient of thermal expansion of the dielectric increases, and will increase when the elastic modulus of the dielectric decreases. The VSV will also increase when porous dielectrics and ultrathin liners are used. At operation conditions, both thermal strains and electromigration make significant contributions to the VSV. We discuss these results in the context of interconnect design.

This has been published and the related references are listed here:

  • Z. Zhang, Z. Suo, and J. He, J. Appl. Physics, 98, 074501 (2005). link
  • J. He, Z. Suo, T.N. Marieb, and J.A. Maiz, Appl. Phys. Lett. 85, 4639 (2004). link

 

Ling Liu's picture

Ninth U.S. National Congress on Computational Mechanics

USNCCM IX, July 22 - 26, 2007
Pre- & Post-Congress Short Courses, July 22 & 26, 2007
Hyatt Regency San Francisco
San Francisco, California

BACKGROUND AND SCOPE
From their inception in 1991, the biennial congresses of the United States Association for Computational Mechanics have become major scientific events, drawing computational engineers and scientists worldwide from government, academia, and industry. The Ninth U.S. National Congress on Computational Mechanics (USNCCM IX), hosted by the University of California, Berkeley, will feature the latest developments in all aspects of computational mechanics, and will broaden the definition of the discipline to include many other computation-oriented areas in engineering and sciences. From applications in nanotechnology and bioengineering, to recent advances in numerical methods and high-performance computing, the technical program will reflect the Congress theme of "Interdisciplinary Computation''. In addition to plenary lectures and minisymposia that highlight the latest trends in computational mechanics, pre- and post-conference short courses addressing advances in multiscale and multiphysics methods, as well as other topics, will be held. Numerous vendor exhibits from Bay Area and national companies and organizations are also planned. Detailed information on USNCCM IX can be found at:
http://me.berkeley.edu/compmat/USACM/main.html

Nanshu Lu's picture

George Rankine Irwin (26 February 1907 - 9 October 1998)

G.R. Irwin during WW II.

Dr George Rankine Irwin (26 February 1907 - 9 October 1998) was an American scientist in the field of fracture mechanics and strength of materials. He was internationally known for his study of fracture of materials. Read more...

Brain Storm and Carbon Nanotubes

Last year, I attended the course ES139/239 in Division of Engineering and Applied Sciences, Harvard University, the innovation in science and technology. The final project of my group was about carbon nanotube (CNT). In the stage of popping up ideas, we did not consider any feasibility issues, and just used our imagination to create fancy ideas. I was inspired by other guys a lot, felt too excited after the evening brainstorm session, and wrote down the ideas I coined up. Some of them are not nonsense, e.g. replacing Cu by CNT as conductor in integrated circuit (IC). Later on, I find a piece of news in nanotoday (Dec. 2005) that the company Arrowhead Research was to provide $680,000 over two years to Duke University to develop technology for IC based on CNTs. Of course, I am not the first one to come up with this idea. But this means the random imaginative idea is very helpful and sometimes feasible. Another point I learned from this course is to write down at least one idea per day. Keep doing this, then you have a large pool of ideas. One year later, you have 365 ideas. Don’t expect every idea to be useful. Even if just one or two of them are great, it is worthy doing. Imagine that if the future technology originated from one of your ideas, you will contribute the society and feel fullness of ecstasy. If you can realize your idea, you can be a millionaire or billionaire, and then lie on the beach of Caribbean to enjoy the sunshine.

Zhigang Suo's picture

The long tail of papers

(Initially posted in Applied Mechanics News on 25 July 2006)

In an entry on pay per paper, I alluded to Chris Anderson's new book, The Long Tail. It should be straightforward to collect page views or down loads or citations of individual papers in a journal. You can plot the numbers of hits of individual papers against the rankings of the papers. Here is the curve for articles in Slate. (Not sure why data stopped at top 500 hits. Why not go further to see a really long tail?) Hope someone in Applied Mechanics will show the same data for JMPS, IJSS, MOM, etc. It will be fun.

Here is the gist of Anderson's observation: If you care about the total sale, as a publisher might, then what matters is the area under the curve; the contribution of the tail may rival that of the head. This much is objective, and should not be controversial.

Now allow me to play a variation of the theme, which is admittedly subjective and possibly controversial. Let's say the net contribution of a journal to new knowledge is proportional to the area under the curve (the subjective part). Then numerous less cited papers may make a significant contribution comparable to the contribution made by the best cited papers.

If you are interested in this argument, you might as well generalize the analysis from a single journal to all journals in a field, or to all journals in science, engineering and medicine. I'm not sure if such a curve has ever been plotted, but the job should not be too hard.

Now, if you are an individual author, surely you'd like to have a lot of hits for your own papers, just as Anderson is celebrating his book becoming a best seller. However, if your job is to increase the total knowledge, as the NSF is set up to do, then you might as well pay as much attention to the long tail as to the tall head.

Carbon nanotubes

Carbon nanotube has been widely investigated and perceived as having great potential in nanomechanical and nanoelectronic devices due to uniqe combination of mechanical, electrical and chemical properties. The carbon nanotubes may be applied (a) as light-weight structural materials with extraordinary mechanical properties such as stiffness and strength; (b) in nano-electronic components as the next-generation of semi-conductors and nanowires; (c) as probes in scanning probe microscopy and atomic force microscopy with the added advantage of a chemically-functionalized tip; (d) as high-sensitivity microbalances; (e) as gas and molecule sensors; (f) in hydrogen storage devices thanks to its high surface-volume ratio; (g) as field-emission type displays; (h) as electrodes in organic light-emitting diodes and (i) as tiny tweezers for nanoscale manipulation, to name a few.

As a postdoc in Xi Chen's group, my current research in the mechanics of carbon nanotubes concentrates in the following areas: a) thermal vibration and application as strain/mass/specie sensors; b) buckling of nanotubes caused by compression, bending, torsion, and indentation; c) mechanical properties of carbon nanotubes in axial and radial directions, and effective continuum modeling; d) fluid conduction in nanotubes. I have published 14 journal papers since 2005 in these areas. I will introduce more details in my blog later.

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