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Joost Vlassak's picture

COMPUTATIONAL METHODS FOR MICRO AND NANO SYSTEMS

Ninth U.S. National Congress on computational mechanics
July 22 -26, 2007. San Francisco, California

A mini-symposium on

COMPUTATIONAL METHODS FOR MICRO AND NANO SYSTEMS

Call for Papers
Micro and Nano Electro Mechanical Systems have recently attracted much attention from the industry and from the scientific community. MEMS are nowadays routinely met in various fields like in the automotive, aerospace and large consumer applications.
It can be said that for various micro systems the pioneering phase has been substituted by a phase of industrial applications. Hence, new challenges concerning reliability, optimization and increasing miniaturizations must be tackled by the designers. All these issues need a multi-disciplinary approach and must be supported by multi-physics numerical and experimental analyses able to contribute to the definition of a unified design and analysis methodology of MEMS and NEMS.

Xin-Lin Gao's picture

Symposium on "Mechanics of Nano-, Bio- and Cellular Materials" at the McMat 2007

CALL FOR PAPERS

The 2007 ASME Applied Mechanics and Materials Conference (McMat 2007)
Austin, Texas, June 3-7, 2007

http://www.ae.utexas.edu/MCMAT07/

Symposium on

Modeling elastomers at Medinstill

I am a senior research engineer at Medical Instill Technologies, New Milford, CT. Our company is currently focused on designing and manufacturing innovative dispensing systems for pharmaceutical and nutritional products, and also their filling systems. You may visit our website (http://www.medinstill.com) for more information.

We are currently exploring elastomer-based dispensing systems for fluids of different viscosities. In relation to this project, we are interested in hiring somebody with a doctoral level education and who has exposure to modeling elastomers, particularly elastomer solid mechanics, adhesion between elastomers, and flow of fluids over elastomers.

Martijn Feron's picture

Web journals threaten peer-review system

The peer review system has been the established way to select publicated research for decades. However, this way of publishing may come to an end.

New developments in this field embrace the idea that research should not be restricted by the iron grip of the journals. The value of the authors work is debated in cyberspace, leading to a number of consequences. Disadvantages include the possibility of a deluge of junk science due to the unfiltered publishing and online abuse concerning unfairly ridiculing rival's work. On the other side scientific discovery could be accelerated and online critiques may help detect mistakes or fraud more quickly.

Already the first initiatives are present, Philica, PLoS (Public Library of Science). Online journals are not boomingly popular, as they have attracted little attention so far. However, possibilities regarding reaching a broad audience in a fast way seem promising...

Horacio Espinosa's picture

The 13th International Conference on Experimental Mechanics

Dear Colleagues:

The 13th International Conference on Experimental Mechanics (ICEM13, http://www.icem13.gr) will be held on July 1-6, 2007 in Alexandroupolis, Greece. It is our pleasure to announce that the Conference will include a special symposium organized by us entitled, “Plasticity, Fracture and Fatigue at the Micro and Nano Scales,” which will focus on recent developments in this area within the larger scope of assessing research needs in a variety of applications of interest.

Zhigang Suo's picture

The Boltzmann Distribution

  • A small system in thermal contact with a large system
  • The Boltzmann factor
  • Partition function
  • The probability for a system in thermal equilibrium with a reservoir to be in a specific state
  • The probability for a system in thermal equilibrium with a reservoir to be in a configuration
  • Thermal fluctuation of an RNA molecule
  • A matter of words

Return to the outline of Statistical Mechanics.

Zhigang Suo's picture

Entropy

  • A dissection of a sample space
  • Entropy of a dissection of a sample space
Zhigang Suo's picture

Probability

  • An experiment that has many possible outcomes
  • Construct a sample space at a suitable level of detail
  • Probability of an event
  • Conditioning
  • Independent events
  • Random variable
  • Use a random variable to specify an event
  • Use a random variable to dissect a sample space
  • Probability distribution of a random variable
  • Variance of a random variable
  • A dimensionless measure of the fluctuation of a random variable

Return to the outline of Statistical Mechanics

Pradeep Sharma's picture

How "hot" is a research topic?

A student pointed me to a recent article on physicsweb. This article discusses a new (scientific) ranking system developed by a German student (Michael Banks) in Max Planck Institute of Solid State Physics to characterize the "hotness" of the scientific subject. If, after reading the popular physicsweb article linked above, you are interested in more details you may wish to read the attached original article posted by Banks. "Carbon nanotubes" emerges at the top of the list.

fengliu's picture

Nanomechanical Architecture of Strained Bi-layer Thin Films:from design principles to experimental fabrication

The nanotechnology of the future demands controlled fabrication of nanostructures. Much success has been made in the last decade in fabricating nanostructures on surface with desirable size and shape, either in serial using scanned-probe techniques or in parallel using self-assembly/self-organization processes sometimes combined with lithographic patterning techniques. However, controlled fabrication of nanostructures remains in general a formidable challenge. For example, despite the enormous success we have so far enjoyed with carbon nanotubes (CNTs), it is still very difficult (if not impossible) to synthesize CNTs with a degree of control that we would like in terms of their size and chirality. Fabrication of nanostructures in many other forms and with other materials is even less developed. There exists a strong need for the development of nanofabrication techniques with higher degree of control. Here, we demonstrate the general design principles of an emerging nanofabrication approach based on nanomechanical architecture of strained bi-layer thin films, which allows fabrication of a variety of nanostructures, such as nanotubes, nanorings, nanodrills, and nanocoils, with an unprecedented level of control.

Namiko Yamamoto for ES240 Problem6

I am a first year PhD student in Aeronautics and Astronautics department at MIT. I also have obtained B.S. and M.S. from the same department. I have taken one Solid Mechanics (graduate level) course at MIT, but since it did not cover waves/vibration or nonlinear plate theory, I look forward to these new topics later in the course very much. My most research work has been done at Technology Laboratory for Advanced Materials and Composites at MIT. My M.S. thesis topic was on micro solid oxide fuel cell. The goal was to design and fabricate thin film tri-layer fuel cell structure that is thermomechanically stable at high operation temperature. We started with mechanical testing to acquire properties, and designed membranes with von Karman plate theory. My PhD topic is nano-engineered composites with carbon nanotubes (CNTs). Solid mechanics is very directly related to these structural tasks including stiffness testing. Generally, having better sense of mechanics behind and having many analysis tools will be greatly helpful. So far I have been having much fun coming to Harvard, taking a little break from MIT (I have been there more than enough, although I still love it there). I hope to learn as much as possible from this course.

Hi :)

Hi everyone, I am Roxanne, a G-2 student in applied physics.  My major was chemical engineering when I was an undergraduate student in Taiwan.  I had no background on mechanics then.  When I was a G-1, I took AP 293 (Deformation of Solids).  This course gave me some ideas on the plastic flow, elastic properties, and dislocations of materials. Math, like partial differential equation and tensors are pretty challenging to me…always.

 

Currently, I am working with Frans, and my research focus is on studying the creep phenomena in metals.

http://deas.harvard.edu/matsci/

Xuanhe Zhao's picture

Xuanhe Zhao

My name is Xuanhe Zhao, and I'm a first year student in DEAS. Before joining Harvard, I got my Master Degree in Materials Engineering from University of British Columbia, Canand. I have took one course on Computational Mechanics, and read a couple of books on theory of elasticity.

 The major goal for me taking ES 240 is to learn how to understand and solve engineering problems, both familiar and unfamiliar, in a intuitive way. In addition, I will further consolidate my background in solid mechanics.

Megan McCain's picture

Megan McCain

I am a first year grad student in bioengineering working in Dr. Parker's Disesase Biophysics Group (http://www.deas.harvard.edu/diseasebiophysics/). I attended Washington University in St. Louis for undergrad, where I double majored in biomedical engineering and biology and minored in chemistry. The only courses I have taken related to solid mechanics are Biomechanics and Transport Phenomena, both of which covered basic mechanics. As an undergrad, I worked in a research lab that focused on cardiac electrophysiology. The lab I am in now is interested in how the mechanical and electrical behaviors of cardiac cells are related, so I need to gain a stronger background in mechanics to match my background in electrophysiology. I hope that this class will help me develop an intuition about the mechanical behavior of objects, which I can apply to the mechanics of cellular events.

Ken P. Chong's picture

National Medal of Science

The nomination of colleagues for awards is one of the most important and gratifying aspects of participating in the scientific community. Help celebrate the contributions of your colleagues by submitting a nomination for The National Medal of Science.

The National Medal of Science was established in 1959 as a Presidential Award to be given to individuals "deserving of special recognition by reason of their outstanding contributions to knowledge in the physical, biological, mathematical, or engineering sciences." In 1980 Congress expanded this recognition to include the social and behavioral sciences. The National Medal of Science is the highest honor the President bestows on scientists. A Committee of 12 scientists and engineers is appointed by the President to evaluate the nominees for the Award. Since its establishment, the National Medal of Science has been awarded to 425 distinguished scientists and engineers whose careers spanned decades of research and development.

Michael Petralia

I completed my undergraduate degree in Mechanical Engineering at The Cooper Union for the Advancement of Science and Art, in New York City. At the undergraduate level, I have taken two courses related to solid mechanics: Solid Mechanics and Stress & Applied Elasticity. Though these courses covered most of the same topics, the focus was not on working with developing the equations for different situations. The majority of the work was in knowing when to apply the equations and coming up with quantitative solutions. Thus my weaknesses will be related to coming up with equations to model various stress situations.

Concerning my research, I am working with Prof. Robert Wood in the microrobotics laboratory. My focus will be on aquatic robots on the order of several centimeters in length. Because of the restrictions inherent in working at this scale, it will be important not to over-design the systems. From studying solid mechanics, I hope to gain the ability to analyze the states of stress and strain in materials such that I can effectively develop efficient systems for microrobotics.

will adams

My name is Will Adams and I am a first year grad student in BME. I have no previous courses in solid mechanics or strength of materials but I have taken two fluid mechanics courses, ES220 and ES123, as an undergrad which contain many of the same lines of thinking. Hopefully the math formalisms of these classes will help in ES240 but having no solids background leaves me with little intuition about experimental results. Hopefully I can acquire this here. I was a BME major as an undergrad here in DEAS.

Adrian Podpirka's picture

Adrian Podpirka

My name is Adrian Podpirka and I am a first year grad student studying applied physics. I came to Harvard after finishing my Bachelors in Material Science and Engineering at Columbia University. As an undergraduate I took Mechanics of Solids with Professor Xi Chen and Mechanical Properties of Materials with Professor Noyan.

Related to this course, my main weakness is the mathematics involved since it has been more then 3 years since I took differential equations. Also, both my undergraduate courses were not tensor based. My main strength in this course would be my understanding of material properties and the phenomenas involved.

My likely research direction will probably be in the field of fuel cell membranes with Professor Ramanathan.

Zhigang Suo's picture

Solid Mechanics Homework 11-15

This set of homework relies on a few elementary facts of the algebra of vectors and tensors.  If you are vague about these facts, see some old notes I wrote when I taught ES 240 in 2006:  node/205/revisions/1385/view

11. Positive-definite elastic energy density
12. The coefficient of thermal expansion (CTE) is a second-rank tensor.
13. Hooke's law for anisotropic, linearly elastic solids
14. Invariants of a tensor
15. A "derivation" of the Mises (1913) yield criterion

Xiao-Yan Gong's picture

Pushing Mechanics to the Up Front of Design

When a mechanical engineer and a material scientist were asked for the root cause of an in-vivo fracture. Mechanical engineer pointed to the loading and the material scientist pointed to the processing. While they both are correct, they both also missed the real ROOT cause, the design.

It is very common that medical device design engineers are so focused on the device functionality that often the very basic mechanics is overlooked. Lack of knowledge on the in-vivo environment (Design Requirements) is another subject to blame. However, it is common that even technology driven companies have gaps between design department and duarability deparment. Up front design engineers do not necessarily keep up with the fast paces of material advances. On the other hand, downstram subject matter experts, device tesing teams or often the R&D departments are not informed of design changes before the design is fixed. The problem is worse often in industrial leaders than in start-ups, but the sympton is the same, problem found in animal studies and/or clinical trials before they reached industrial subject matter experts.

Xiao-Yan Gong's picture

Mechanics in Medical Implant Industry

The major challenge in medical implant industry is the knowledge about human body. Had we know the human body and its functions better, we can make better and reliable implants. Below are two examples that I have learned.

Let's start from stent, a small, lattice-shaped, metal tube that is inserted permanently into an artery. The stent opens the narrowed artery so that an adequate supply of blood can be restored. See this FDA site for further detail.

Stent has revolutionized the treatments for cardiovascular disease and the interventional system. However, stent fractures are commonly observed in-vivo in the past years and has become a concern for patient wellness and therefore a challenge/opportunity for mechanical engineering. Both the engineering and the medical care societies have to work together to solve this issue. It is very surprising that little publications are available to study the key issues such as artery deformation, motion, its mechanical properties and its variations among patient age, race, and other factors. As a result, current stents, even they have been proven to be lifesavers for many patients, they are not necessarily a satisfactory product for a mechanical engineer. We can not wait for the medical care society to give us the information because they often concern and focus on different issues than us. In addition, they can not work alone to come up with the necessary equipments. Therefore, we need proactive to interact and help each other to get what we want. The day we know our interventional system better is the day that we can make better stents because stents can only be as good as our knowledge to the interventional system.

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