The number of registered users of iMechanica passed 8000 this afternoon.  The total number of posts is 3622, and the total number of comments 8429.  The total number of hits was 3.4 millions in March, 5.6 millions in April, 2.4 millions in May, and 2.7 millions in June.

From time to time people ask if I know other websites like iMechanica but focusing on different branches of engineering.  This morning I saw a recently compiled list of Top Engineering Blogs, and was delighted that iMechanica was ranked close to the top.  I'm aware of the widespread cynicisms among iMechanicians about rankings of all kinds.  But, heck, ranking is good if you are ranked high.  As Freeman Dyson would say, being consistent is a weakness of mind. 

I finally got around to read Does IT Matter, the 2004 book by Nicholas Carr.  He used the phrase IT (Information Technology) in "its commonly understood sense today, as denoting all the technology, both hardware and software, used to store, process, and transport information in digital form."  He explained, "The meaning of "IT" does not encompass the information that flows through the technology or the talent of the people using the technology."

I'm in Washington DC attending a small workshop entitled Understanding and Exploiting Nonlinearity.  Yesterday several talks described recent developments of nonlinear dynamics, the kind of phenomena that can be described by a set of nonlinear ordinary differential equations.  Years ago, when the theory of chaos was in vogue, I looked at several textbooks on nonlinear dynamics, and tried to apply a few elementary ideas to evolving structures in materials.  This time I learned that many of the esoteric ideas of nonlinear dynamics have found applications in modeling natural phenomena and creating new devices.  Perhaps it is a good time to relearn nonlinear dynamics.

At the invitation of David Clarke on behalf of the UCSB/Los Alamos Institute of Multiscale Materials and Structures, I gave the following three lectures:

1. Large deformation and instability in dielectric elastomers
2. Large deformation and instability in swelling polymeric gels
3. Mechanics and electrochemistry of polyelectrolyte gels

The abstracts follow, and the slides are attached at the end of this post.

People sometimes complain that reading iMechanica takes time.  This is because iMechanica has a large number of pages, and new pages are added frequently.  If you go directly to iMechanica, you have to load individual pages one by one.  

RSS feeds provide a perfect solution.  It is very easy to set up on your computer a RSS feed reader.  If you look at the reader once a day, say, all the new posts are right in front of you at a single click.  Better yet, you can use the same reader to subscribe to full text of The New York Times, abstracts of Nature, titles of JMPS...  The service is completely free.  Learn to subscribe to RSS feeds today.

iMechanica has gone a long way since its launch in September 2006.  The number of registered users is approaching 7,000, and the number of entries (posts and comments) has exceeded 10,000.  iMechanica is created and maintained by volunteering mechanicians, and is not funded by anybody.  The remarkable growth of iMechanica has surprised even the most optimistic among us.  Many have noted, however, that iMechanica is predominantly used by junior mechanicians.  This demographics is unremarkable for any web site, but many feel that we can benefit tremendously from the participation of established mechanicians. 

On the Web of Science my name appears sometimes as Suo Z and sometimes as Suo ZG.  If I search for Suo Z*, papers by a biologist named Suo ZM mix in.  Now Suo is a very rare name.  I cannot imagine how Wang JS searches for his papers.  Last year Michelle Oyen and I talked about assigning a unique identifier to each researcher, much like assigning an ISBN to each edition of a book, or assigning a DOI to each paper.

If you have a curious child at home, you will hear no end of Wikipedia.  In 2005, Michael Suo introduced me to Wikipedia, which has since become a source of inspiration for iMechanica.  

iMechanica has a search box, but its algorithm is less sophisticated than that of Google.  You may wish to use Google to search content on iMechanica.  For example, if you are looking for friction in iMechanica, type into the Google search box: friction site:imechanica.org

If instead you are only interested in rolling friction, then type into the Google search box: "rolling friction" site:imechanica.org.  The quotation marks ensure that all the included words appear in search results.

Rob Wood teaches a course on micro/nano robotics, and asks me to give a 30-minute tutorial on the theory of dielectric elastomer actuators (DEAs).  I attach my slides, which might be useful to you if you'd like to include this topic in your class.  The tutorial draws upon work in the literature, as well as recent work in my group:

Early this week the number of registered users passed 6000.  Our growth rate remains nearly a constant, about 10 new users per day. In January Teng plotted some basic statistics of iMechanica. 

I'm attaching slides of a talk that I gave yesterday at the Schlumberger-Doll Research Center.  In preparing the talk, I made liberal use of slides prepared by Wei Hong for his own presentations.  The talk is mainly based on the following papers:

To students of AM 105a:

On 26 October 2007, Albert Tsou sent in the following Q & A.

Q: Why did the mathematician name his dog "Cauchy"?
A: Because the dog left a residue at every pole.

As you know, certain sections in Saff and Snider upset me, and I have deviated from the book. We all agree that no text should be held as an authority. But now, both you and I are paying for the deviation.

The notes here follow closely my lectures. Several students have mentioned that their own notes may reproduce what was written on the blackboards, but not what I said in class, so that they found it hard to reproduce the ideas.

In today's class of complex analysis, my co-instructor Scott Norris was lecturing on resonance.  He mentioned a YouTube video of the Tacoma Narrows Bridge.  Also instructive is the entry of the bridge on Wikipedia. 

Michael Brenner has just pointed out to me this video of the Moebius transformations.

I'm teaching Applied Mathematics 105a this semester.  The main content of the course is complex analysis.  The course is taken mainly by undergraduate students in Engineering, Physics, and Applied Mathematics.  There are about 70 people in the class, which makes it the largest class I have taught in the last 10 years. I have never taught a course on complex analysis before, but have used complex analysis in my research, and have taught the method of complex variables in my graduate course on elasticity.

In a previous post, Learning to be a PhD advisor, I wrote about learning to do my job from students.  Over the years, I have also learned from writings of other scientists on doing research, its dynamics:  competition, despair, and exhilaration...  Here is a small sample that occurs to me this morning. 

In preparing cases for faculty appointments, my colleagues in other fields often ask about citations of each candidate and his or her comparees.  Despite obvious resistance, my colleagues give following reasons:

I attach slides for an ASME talk, which is based on a recent paper.

I attach the slides of a presentation at the ASME meeting.  The talk was based on several recent papers on soft active materials (SAMs).  To give an uncluttered picture of the pull-in instability, I have removed all discussion on the Maxwell stress.   As you can see, the problem can be studied without ever mentioning this troublesome notion.

I have recently given seminars on Mechanics of Soft Active Materials (SAMs) at several universities, using this set of slides (pdf, 1.4 MB).  I also attach the slides as ppt; please feel free to use anyway you want.  Here is an abstract of the seminars, followed by a list of papers published by my group on the topic.  Each paper has initiated on iMechanica a thread of discussion, to which I'll link.  I'll give a talk at the ASME Congress in Seattle, in Session 10-12-4 Instability in Solids, 9:45 am - 11:15 am, Thursday, 15 November 2007.  

This semester I'm teaching an undergraduate course on functions of a complex variable.  A student has just sent me a message:

Q: Why did the mathematician name his dog "Cauchy"?
A: Because the dog left a residue at every pole.

*         *         *         *

I received an email several weeks ago with the following quote:

You are cordially invited to attend a reception, hosted by Harvard School of Engineering and Applied Sciences, during the MRS Fall Meeting, on Monday, 26 November 2007, from 7:30 pm to 10 pm, at Independence Room East, 2nd Floor, Sheraton Boston Hotel & Towers, 39 Dalton Street, Boston, MA.

Dean Venky Narayanamurti, Joanna Aizenberg, Michael Aziz, Shriram Ramanathan, Frans Spaepen, Zhigang Suo, Joost Vlassak