Universal Rule

Book Reviews

Friday, March 19, 2004

Modeling dissipative acoustics with Elmer -- Comment()
I made an animation (using Snapz Pro 2.0) of Elmer displaying the solution to the tutorial example 9, which discusses modeling dissipative acoustics. The model describes propagation of sound waves in a circular tube. Here are the results (in QuickTime format):

I'm wondering if there is a Mac OS X tool for making movies out of still images. Snapz Pro works ok, but it would be nice to be able to compose the movie from still images output directly from Elmer. So, you could do something like the following in Elmer:

do i 100 301 {math s=2*pi*($i-100)/200; 
  math p=cos(s)*Flow.7-sin(s)*Flow.8; 
  display; screensave t$i.ppm;}

Here we generated 201 pictures into files t100.ppm ... t301.ppm.

Update: GraphicConverter can generate the animation easily. (Command File/Export Slideshow to Movie...) I re-generated the movie with GraphicConverter, using the highest quality and 24 pictures per second (see here).

-- Comment()
Blog Libel Threat towards Gavin Sheridan by John Gray: "I must retract a remark made on my blog last November, and to publish an apology, within three weeks. [...] I am not seeking a campaign for vindication, but I will attempt over the next number of days to detail the story, the ins and outs of internationl legal jurisdiction, the possibility of being sued from another country - and what exactly constitutes defamatory remarks." [via Dan Gillmor's eJournal]

For more details about pseudoscientific charlatans, check out The Doctor Is Out: "Little wonder that the public is ill-informed about empirically supported treatments when most of their knowledge of mental health issues comes directly from the likes of 'Dr. Phil' McGraw, radio show host 'Dr. Laura' Schlessinger (whose doctorate is in physiology and not psychology or psychiatry), relationship 'expert' John Gray (who holds no professional license), and motivational guru Tony Robbins (a practitioner of the pseudoscientific Neurolinguistic Programming)."

A new visiting researcher -- Comment()
Today in my group starts a new visiting researcher, a Ph.D. student. We already had a visiting post-doc. Both researchers study numerical methods and mathematical modeling using Elmer as the main tool. This kind of knowledge transfer between us and universities (and in some cases industry) has worked out really well.

-- Comment()
The coming crisis in computational science by Douglass Post: 'A key figure of merit is the "time to solution", the time between the identification of a problem and the delivery of validated and analyzed computational solution. For the reasons quoted earlier, the "time to solution" is growing in many cases, not decreasing.'

-- Comment()
I noticed that Quadric Surfaces at the web site of American Mathematical Society (AMS) shows my animation of quadratic functions:

First I was suprised, but then I remembered AMS asking permission to use the graphics.