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Growing pains of iMechanica

Dear fellow iMechanica users,

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7000+ registered users of iMechanica

The number of registered users of iMechanica reaches 7000 on 11 May 2008. So far, our fellow iMechanicians have contributed 3172 posts and 7425 comments.  The evolving statistics of iMechanica
(see the latest updates here and here) shows a steady growth with no sign of slowing down. 

Check out the earlier milestones of iMechanica when the number of registered users reached:

6000

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iMechanica back on service

Dear fellow iMechanicians:

After some technical problems over the past weekend, iMechanica is now back on full service. We apologize for any inconvenience this may cause and thank for your patience.

We are particularly grateful to Ms. Lesley Lam in OIT of Harvard School of Engineering and Applied Sciences for her prompt fix of the problem.

 

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Making flexible metallic glasses

Well-known for its high yield strength, metallic glass often suffers from its low ductility and intrinsic brittleness, as discussed in a recent iMech jClub theme on plasticity and failure in metallic glasses led by

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Mechanics of microtubule buckling in living cells

As the most rigid cytoskeletal filaments, microtubules bear compressive forces in living cells, balancing the tensile forces within the cytoskeleton to maintain the cell shape. It is often observed that, in living cells, microtubules under compression severely buckle into short wavelengths. By contrast, when compressed, isolated microtubules in vitro buckle into single long-wavelength arcs. The critical buckling force of the microtubules in vitro is two orders of magnitude lower than that of the microtubules in living cells.

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Symposium on Mechanics of Slender Structures (MoSS) 2008

From Prof. Weidong Zhu at
University of Maryland, Baltimore County

Dear Colleague,

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iMechanica: 5000 registered users, 9.5 million web hits


Launched on 9 September 2006, iMechanica is the web of mechanics and mechanicians.  The mission of iMechanica is twofold:

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NYT most popular article in December features MIT physics professor

At 71, Physics Professor Is a Web Star

Most frequently e-mailed by NYTimes.com readers in the past 30 days, the above article features MIT physics professor, Walter H. G. Lewin, on how his free physics lecture videos online have won him devotees all over the world.

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Everything is miscellaneous (Video)

While preparing a talk on iMechanica , I came across the following video "Information R/evolution" by Michael Wesch, an assistant professor of anthropology at Kansas State University.  This thought provoking video echoes a recent comment on "The future of knowledge?"

Enjoy!

 

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The Future of Conference

Attending conferences is one of the essential professional activities for scientific researchers. Conferences take various forms, such as community-wide meetings (e.g., MRS meetings, ASME congress, APS meetings), and topic-focused meetings/workshops (e.g., Plasticity07, Gordon Research Conferences(GRC)).  While people have different preferences on the types of conference to attend (e.g., see a recent iMech poll initiated by Biswajit Banerjee ), here are some common positive driving forces to motivate one to attend a conference:

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Post-Doc position on surgical simulation at University of Maryland, College Park

From Prof. Jaydev P. Desai at University of Maryland:

 

Post-Doc position at University of Maryland, College Park:

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Minutes of iMechanica get-together at McMat 2007

On 6 June 2007, about 50 mechanicians attended a special session at the McMat 2007, "iMechanica.org get together". The attendees of this special session came from various job sectors, such as academia, industry as well as government agencies. The session was chaired by K. Ravi-Chander and Rui Huang, who also served in the organizing committee of McMat 2007.

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Post-doc position: Surgical Simulation in a NIH project

From Prof. Jaydev P. Desai at University of Maryland

Post-Doc Position

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IBM Airgap Microprocessors enabled by self assembly (Video)

An earlier post by Xiaohu Liu reported IBM's latest progress in microprocessors. IBM has figured out how to control and perfect the self assembly process to create trillions of tiny, nano-sized holes across a chip, which speed electrons that flow across wires inside the chip and reduce the power consumed by 15 percent.The following short video may help us understand a little bit more about the new technology. More videos, audio and images on this are available here (free, but registration needed)

Enjoy.

-Teng

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iMechanica now has 2000+ registered users

iMechanica was lunched on 9 September 2006. It took about five months for iMechanica to see its 1000th registered user. Today we are welcoming the 2000th registered user after only another two and half months.

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Online meeting scheduling

Scheduling a meeting with more than 3 participants can be a headache. The organizer often needs to email or call the group, and wait for feedbacks. Quite often both the organizer and the participants need to go through such a process several rounds to finalize the schedule.

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The future role of iMechanica

Since iMechanica went official on 9 September 2006, its growth has always been accelerating. As of 22 February 2007, the total number of hits on iMechanica reaches 1,000,000+, iMechanica has 1252 registered users, 908 posts and 1308 comments.

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Delocalizing Strain in a Thin Metal Film on a Polymer Substrate

Teng Li, Zhenyu Huang, Zhichen Xi, Stephanie P. Lacour, Sigurd Wagner, Zhigang Suo, Mechanics of Materials, 37, 261-273 (2005).

Under tension, a freestanding thin metal film usually ruptures at a smaller strain than its bulk counterpart. Often this apparent brittleness does not result from cleavage, but from strain localization, such as necking. By volume conservation, necking causes local elongation. This elongation is much smaller than the film length, and adds little to the overall strain. The film ruptures when the overall strain just exceeds the necking initiation strain, εN , which for a weakly hardening film is not far beyond its elastic limit. Now consider a weakly hardening metal film on a steeply hardening polymer substrate. If the metal film is fully bonded to the polymer substrate, the substrate suppresses large local elongation in the film, so that the metal film may deform uniformly far beyond εN. If the metal film debonds from the substrate, however, the film becomes freestanding and ruptures at a smaller strain than the fully bonded film; the polymer substrate remains intact. We study strain delocalization in the metal film on the polymer substrate by analyzing incipient and large-amplitude nonuniform deformation, as well as debond-assisted necking. The theoretical considerations call for further experiments to clarify the rupture behavior of the metal-on-polymer laminates.

Related posts and discussions

Tension of Cu film on Pi substrate
Local thinning of Cu film
High ductility of a metal film adherent on a polymer substrate

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Mechanics of flexible macroelectronics

The following entry was first posted in www.macroelectronics.org on 8 May 2006.

Flat-panel displays are rapidly replacing cathode-ray tubes as the monitors of choice for computers and televisions, a commercial success that has opened the era of macroelectronics, in which transistors and other micro-components are integrated over large areas. In addition to the flat-panel displays, other macroelectronic products include x-ray imagers, thin-film solar cells, and thin-film antennas.
Like a microelectronic product, a macroelectronic product consists of many thin-film components of small features. While microelectronics advances by miniaturizing features, macroelectronics does so by enlarging systems. Macroelectronic products today are mostly fabricated on substrates of glass or silicon; they are expensive, fragile and not readily portable when their areas are large. To reduce cost and enhance portability, future innovation will come from new choice of materials and of manufacturing processes. For example, thin-film devices on thin polymer substrates lend themselves to roll-to-roll fabrication, resulting in lightweight, rugged and flexible products. These macroelectronic products will have diverse architectures, hybrid materials, and small features. Their mechanical behavior during manufacturing and use poses significant challenges to the creation of the new technologies.

A recent review paper by Suo et al. describes ongoing work in the emerging field of research – mechanics of flexible macroelectronics, with emphasis on the mechanical behavior at the scale of individual features, and over a long time. The following topics have been discussed in the paper:

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Gecko, Spiderman and Climbing Robot (Video)

I am at Boston for MRS 2006 Fall meeting this week, where I met a real "spiderman" at the poster session tonight. I'd like to share with you the following videos which were posted at YouTube by the "spiderman" himself, Mr. Jose Berengueres at Tokyo Instititute of Technology.

Mr. "Spiderman" also has posted a video on fasting climbing robot.

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The Future of Cell Phone?

Here is one answer from Nokia.


Nokia 888 communicator, a concept design which recently won the Nokia's Benelux Design Award. It uses liquid battery, flexible touch display, speech recognition, touch sensitive body cover which lets it understand and adjust to the environment. It has a simple programmable body mechanism so that it changes forms in different situations. Don't forget to enjoy a video demo of this cell phone of future.
Yet one more future application of flexible electronics, it's clear there're great mechanics and materials challenges in making electronic devices flexible. It will be great mechanicians can help accelerate the advance of this emerging technology.

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