9/11 Simulation Taxes Purdue Servers

Source: http://cityroom.blogs.nytimes.com/2007/06/22/911-simulation-taxes-purdue-servers/

June 22, 2007, 10:48 am

9/11 Simulation Taxes Purdue Servers

By Sewell Chan

It’s unusual for an academic computer-science department to brag about its prowess on YouTube, but that’s exactly what happened this month after Purdue University in West Lafayette, Ind., released a study into the causes of the collapse of the World Trade Center on Sept. 11, 2001.

A two-year Purdue University study released this month supports a federal agency’s conclusion that the impact of the hijacked jetliners stripped away fireproofing material, causing the weakened towers to eventually collapse under their own weight.

The video is a counterpoint to the conspiracy theories that still surround the collapse of the World Trade Center (and such outspoken figures as Rosie O’Donnell appear to be sympathetic to these arguments).•

The video went unnoticed for a while. Purdue issued a news release on June 12 noting its research. The university said it hoped the findings would help to improve the structural integrity of future skyscrapers. The nearly five-minute video with the release depicted “a scientifically based animation of the 9/11 attack.” Initially, the video was developed to help engineers study the effects on the twin towers of the impact of the planes; a more recent version was enhanced with a translator application to “automatically translate simulation data into a more realistic 3-D animation scene.” (Sorry, I wish I could explain how that translation works, but I can’t.)

The updated version of the 9/11 video became available on the Purdue computer-science department’s Web site on April 16, but things started to change on June 12.

But as a Purdue Web site explains:

The download rates of this large video file (122MB) averaged only a few each day. However, the CS internet web servers started to sweat shortly after Purdue announced this state-of-the-art 9/11 animated visualization video. The Purdue press release about the visualization work was picked up by various news sites, including physorg.com and the popular digg.com. The results were immediate. CS Facilities and Network Administrator, Dan Trinkle said, “At about 5:00pm the CS web server started receiving about 1500 hits an hour. If they were all World Trade Center Simulation Photosuccessful, that would have been about 190 GB per hour of file transfer.” During the 8:00am-9:00am hour the next morning, the video had over 7900 hits — almost 1TB if successful. The CS server was not able to serve the file quickly enough, so browsers would time out. Most of the hits at that time were only partial transfers so the high number could be attributed to retries.

At first, CS replaced the video with an error message (small text file). Researchers then uploaded the video to YouTube. Trinkle comments, “This site is better able to handle widespread distribution of videos.” Once that was done, CS configured the server to redirect requests to the YouTube location.

For the rest of the day, CS saw access rates over 700 per hour and as high as 2000 per hour redirecting requests to YouTube. By the end of the day CS had handled over 38,000 hits from over 16,000 different sites. By Thursday, June 14th most people were accessing the video directly from YouTube. The YouTube video has been viewed over 87,000 times.

In addition to the YouTube version, the video and a faster-loading version of the video also remain available on the Purdue Web site — provided, of course, the university’s servers have not been overwhelmed.)

The study was the first to use 3-D animation to provide visual context to the attacks, Christoph Hoffmann, a professor of computer science and one of the lead researchers on the project, told The Associated Press. ‘’One thing it does point out… is the absolute essential nature of fireproofing steel structures,'’ he said. ‘’This is something that wasn’t done originally in the World Trade Center when it was built.'’

The A.P. continues:

The report concludes that the weight of the aircraft’s fuel, when ignited, produced ‘’a flash flood of flaming liquid'’ that knocked out a number of structural columns within the building and removed the fireproofing insulation from other support structures, Hoffmann said.

The simulation also found that the airplane’s metal skin peeled away shortly after impact and shows how the titanium jet engine shafts flew through the building like bullets.

Ayhan Irfanoglu, a Purdue professor of civil engineering, said half of the building’s weight-bearing columns were concentrated at the cores of the towers.

‘’When that part is wiped out, the structure comes down,'’ Irfanoglu said. ‘’We design structures with some extra capacity to cover some uncertainties, but we never anticipate such heavy demand coming from an aircraft impact. If the columns were distributed, maybe, the fire could not take them out so easily.'’

The Purdue report essentially echoes an investigation by the National Institute of Standards and Technology, which recommended that cities raise fire standards for skyscrapers and develop new fire-resistant materials for tall buildings. That investigation focused on damage to the fireproofing of the twin towers but did not blame the collapse on the materials or design of the trade center.