iMechanica - video - Comments

Sınıf

asykro — Wed, 13 Feb 2008 16:49:19 -0500

Tacoma Bridge Failure was Due to Flutter

Madhukar Vable — Sun, 23 Dec 2007 04:43:07 -0500

Hope I do this right as I am new to this.

I believe the failure of
Tacoma Bridge was not due to resonance but due to
aerodynamic instability of flutter. [See Billah K.Y. and Scalan R.H. (1991) "Resonance, Tacoma Narrows Bridge Failure and Undergraduate Physics Textbooks" Am. J. Phys. Vol 59, No. 2, pp 118-124).

Flutter occurs when the
bending and torsion modes couple. In this coupled mode the
deformation causes the aerodynamic loads to increase which in turn
causes additional deformation and the cycle grows till the stucture
breaks. Today wind tunnel testing of suspension bridges is mandatory
but was not understood in bridge design at the time Tacoma Bridge was
built.

Madhu

Multiphysics (CFD + Structural) Software for Bridge Dynamics

Ondrej Kalny — Fri, 14 Dec 2007 01:12:06 -0500

In September, I attended IABSE (International Association for Bridge and Structural Engineering) symposium in Germany. It was interesting to see several presentations dealing with advances in computational modeling of bridge dynamics. These programs combine CFD with structural models and are becoming so powerful that can virtually eliminate wind tunnel testing, at least during the conceptual design stages.

ok, BridgeArt.net

useful website for mobius transforms

Zhigang Suo — Tue, 11 Dec 2007 20:38:07 -0500

A message from Meghan Purdy:

Hi Professor Suo,

I just found this very useful website. It lets you apply any Mobius transform to a lot of shapes on the z-plane, and it's really useful for checking answers on this homework. You may want to pass this on to the other students.

http://www.math.ucla.edu/~tao/java/Mobius.html

Best,
Meghan Purdy

Tacoma Narrows leads to the "Windbelt"

Mark E. Walter — Mon, 10 Dec 2007 13:06:31 -0500

A young inventor says that the Tacoma Narrows Bridge inspired him to invent the "Windbelt" to generate electricity.

http://www.humdingerwind.com/windbelt.html

Mobius transformation

Biswajit Banerjee — Mon, 10 Dec 2007 10:12:44 -0500

Just wanted to point out an earlier thread on the topic at http://imechanica.org/node/1619

Thanks for the link!

Dhruv Bhate — Sun, 14 Oct 2007 16:08:30 -0400

Interesting to see how this develops!

Embedded YouTube movie can not be shown

Kejie Zhao — Sat, 13 Oct 2007 22:07:19 -0400

Hi Prof. Li,

Many thanks for the clear steps of posting a vedio. But now I find the embedded YouTube movies can not be shown, only left a yellow block area, in my blog. I also find this problem is encountered in other recent posts of Channel vedio. I hope this is my Internet Explore problem, but not a general one. Thank you

Kejie Zhao

Thanks for your information

Joseph X. Zhou — Sun, 07 Oct 2007 16:52:38 -0400

Thanks for your information about the version with explanation, which is exactly what I am looking for. You are absolutely right that the true image of inner space of a cell should be filled with lots of small molecules: water, ligand and various ions Ca+, Na+ etc. Here the video takes some artistic liberties to make it look empty. However, it is good to do so since we can focus on a single mechanis at a time.

Great video of the cell, with explanations

Zhigang Suo — Sun, 07 Oct 2007 07:24:37 -0400

Thank you so much for pointing to this great video. The video highlights some molecular processes. In addition to large molecules featured in the video, should I assume that the space is filled with water or other small molecules?

Here is another version of the same video pointed out by Teng Ti. This version also has accompanying explanation.

Gecko and fluids

Aaron Goh — Sun, 30 Sep 2007 10:51:07 -0400

Can a gecko climb a wet wall, e.g. after the wall is exposed to rain? What about a wall which is freshly painted and the paint is not dry yet?

Thanks for sharing this

Ehsan Tarkesh — Fri, 28 Sep 2007 23:02:47 -0400

Thanks for sharing this video. This is a very interesting educational tool.

Cool video demo

Teng Li — Fri, 28 Sep 2007 22:53:33 -0400

Very instructive video. Perfect demo in classroom.

When you finish watching the video, try the related videos at the bottom. Some of them are also cool.

Thanks, Biswajit.

Re: Mobius transformation

Biswajit Banerjee — Fri, 28 Sep 2007 21:36:51 -0400

This video has been mentioned in this weeks Science. The link is http://www.sciencemag.org/cgi/content/full/317/5846/1858#article9

Biswajit

That is really fantastic!

ilandron — Wed, 29 Aug 2007 02:16:36 -0400

That is really fantastic! The world is amazing.

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