Thursday, September 13, 2007


More Nine-Eleven

NIST agrees.

At a press briefing in New York City on April 5, the National Institute of Standards and Technology
(NIST) presented its analysis of how the World Trade Center (WTC) towers collapsed after two
aircraft were flown into the buildings by terrorists on Sept. 11, 2001. The study is the most detailed
examination of a building failure ever conducted.
“Like most building collapses, these events were the result of a combination of factors,” said Shyam
Sunder, lead investigator for the agency’s building and fire safety investigation into the WTC disaster.
“While the buildings were able to withstand the initial impact of the aircraft, the resulting fires that spread
through the towers weakened support columns and floors that had fireproofing dislodged by the impacts.
This eventually led to collapse as the perimeter columns were pulled inward by the sagging floors and
The probable collapse sequences update and finalize hypotheses released by NIST last October. The
sequences are supported by extensive computer modeling and the evidence held by NIST, including
photographs and videos, recovered steel, eyewitness accounts and emergency communication records.
Additionally, this information was used to document a variety of factors affecting the performance of the
buildings, the efforts of emergency responders and the ability of occupants to escape prior to the collapses.
In turn, NIST has identified a number of future practices and technologies that potentially could have
enhanced building performance and life safety capabilities on 9-11 had they been available for



MSNBC replayed some tape from the morning of 9/11/01 and I watched it for a while. I was not impressed by the idea that the collapse was brought about by conspirators who had planted explosives; nor was I impressed by the notion that it was caused by collisions with the airplanes. My conclusion was that it was brought down by the fires. I suspect that if a floor of the WTC was engulfed by fire from any cause the building would have collapsed. The authorities might have wanted to cover up that vulnerability as much as anything else.

Why would buildings have been built that were so vulnerable to contact with the air traffic, considering how heavy that is in the New York Metropolitan Area? That's where Prof. Petroski's book comes in. There are lots of "other" forces that cause engineers to push designs to the edge of failure, and sometimes beyond that edge--aesthetics, greed, convenience of construction, etc. And sometimes that leads to lots of casualties--in this case over a million Iraqis have died and more millions displaced by the war that was justified by the 9/11 disaster.

But we won't learn from such a disaster if we don't look at it closely and honestly, and we are not in the kind of historical period that makes that possible.

Monday, September 10, 2007


Post-Industrial Engineering

Henry Petroski's book To Engineer Is Human raised an interesting question. One of the significant constraints on design in our contemporary world is cost. If you make something stronger (i.e., less failure-prone) than it needs to be, somebody else will design a thing that is cheaper to make and undersell you. In fact I had used that idea myself in an essay, the purpose of which I have forgotten: I said that if he wanted a microwave cavity that wasn't lossy a physicist would hog it out of a gold ingot, if he had one, whereas an engineer worries about 10 minutes of a worker's time.

That makes sense in our society in which money is the primary mark of social status. The protestant-industrial revolution has been characterized by upward mobility of the lower middle class by the acquisition of money; as opposed to the prior system of establishing status by being or serving a warlord. But the industrial age is over. Upward mobility stopped around 1950 because the sign of social status was the waste ( or unnecessary use) of resources, and there aren't enough resources to allow the women and people of color who live outside the industrialized world to waste resources at the same rate as bureaucrats in the developed world do. In fact the developed world is being characterized by downward mobility of lower-level bureaucrats who are becoming, in Toynbee's sense, an "internal proletariat".

The internal proletariat shows itself in the need to limit immigration from the undeveloped world, i.e., from the "external proletariat". That external proletariat is beginning to express hostility toward Western Civilization: as direct guerilla warfare among Islamic peoples, and as anti-colonialism among the Bolivarians of Latin America. According to Toynbee's scenario, Western Civilization will turn itself into a military dictatorship and run itself into the ground. Until that final stage we will experience constant guerilla war, since the guerillas do not have the infrastructure to "win" and Western Civilization is only trained to waste resources rather than use them to "win" and is too decadent to do anything creative.

The question is not how we save Western Civilization. It has served its purpose and needs to get out of the way with as little trauma as possible. The question is how we design the infrastructure of the post-industrial society.

One way has been described in This was based on the statement by Norbert Weiner, that when computers and robots are fully developed no one would be allowed to work unless they could do something better than the robots and computers. That suggested to me a society with an elite "Working class" of people doing creative activities and a larger "Liesure class" of people who merely needed to keep themselves amused.

All people would have an equal right to be themselves and food, shelter and health services would be there for the taking, produced and distributed by robots and computers and other, less sophisticated, machines. Each person would have, as a matter of right, his or her proportion of the annual global production.

The Working class would consist of "Journeymen" who were able to work with little or no supervision and "Masters" who were elected by their peers on the basis of a masterwork and who could take on apprentices. The apprentices would become journeymen when their masters decided they were ready.

The Liesure class would consist of groups of people whose customs showed mutual compliance in localities; and individualists who gathered in "Bohemias". Bohemias would be locations where the ordinary residents might not be creative but were capable of tolerating creative people. These areas might resemble the Latin Quarter or The Village or Haight-Ashbury.

I proposed that the primary universal constraint on behavior would be an abhorrence of waste, possibly because it was identified with the elite of the late industrial period. Whatever else anyone believed it would be considered extremely bad taste (or "nekulturni") to waste. There would be a universal, emotional adherence to the motto that used to be in military mess-halls: "Take what you need but eat what you take".

That would provide the tension in the creative act that cost does in our money-based society. It would eliminate the needless duplication of goods we now see in developed societies: if there were two products with the same function, quality and use of resources, the better would be chosen (by peer review) for production. Status among design workers would be determined by whose designs remained in use.

Sunday, September 09, 2007



When we are in the US most of our time is spent seeing doctors, or waiting to see doctors, or having operations in hospitals or clinics or nice stuff like that. To amuse ourselves without spending too much money we spend Saturday going to Yard Sales. We buy a lot of books and send them down to the Caribbean in barrels along with stuff that's hard to get down there, because a used paperback book costs about what a laborer gets for a day's work. If we don't want to keep them we donate them to the public library.

Once in a while we run across a real gem. Yesterday I found a copy of To Engineer Is Human by Henry Petroski. It is subtitled "the role of failure in successful design" and his view of the history of engineering considers not only that failure is inevitable but that the thoughtful analysis of failure is a stimulus to the evolution of engineering design.

I sat down and, pretty much, read it through. I have to say that I enjoyed it more than any book that I have read in recent years.

Part of that is nostalgia, of course, I not only had, and used at MIT, a K&E LogLog Decitrig slide rule like the one he uses as an example, but I had a book of log tables from the Bureau of Standards for pushing some calculations a couple of decimal places. When I worked at Yale I bought for our project an early Marchant electronic calculator that was as big as a Monroe mechanical calculator, cost $1500 and had the same power as the ones you can now get in a dollar store. Petrosky uses the sliderule as an example of the historical limitations of technology.

But new technology brings in new limitations. While in graduate school I did part time technical writing on the Wright YJ67 jet engine. Evidently their engineers wrote so badly that the company shipped the raw information to the small firm I worked for and we wrote their reports. In one case I ran across a diagram which showed the temperature distribution in the combustion chamber With the temperatures stated to 4 decimal places. It may be that their engineers believed it, but nobody who actually tried to measure temperature in a combustion chamber would take more than two decimal places seriously. It was probably the result of a computer simulation and computers don't get to take measurements.

I also did a failure analysis of a fuel control for that engine. We got the job because our overhead was lower than anybody else. I taught myself what it was about, hired a college student for the summer, and got a commendation from the Air Force. We got it to perform the mission by saying that the pilot had to push a test button every few minutes.

Nobody was happier than I was when the Air Force scrapped that engine.

I also taught a course on nuclear safety for prospective engineers for the nuclear freighter Savannah where one student was transferred from graduate school in maryland and a couple of the others had GED certificates and 25 years at sea. The chairman of the department asked me not to go too heavy on safety because one of my class was a shop steward and they didn't want him to know too much. I did go heavier than I might have if he hadn't said that, but I was happy when the NS Savannah was decommissioned.

I also learned something about brittle fracture. When I was cleaning up toxic waste sites I had a client who had leaded gas on the groundwater under his gas station. He hadn't had leaded gas in those tanks for twenty years but it was downgradient of a landfill where the National Guard had reportedly dumped drums of leaded gas.

The State forced him to exhume those gasoline tanks and the state inspector found a leak by pounding on a rust spot with a sledge on an extremely cold winter day. This was two weeks after the tank had passed a standard leak test. But the daily cover on the landfill was excavation material from the "Big Dig" and I was the only one who wanted to look into that carefully. After all, if they found the excavated material was contaminated it would have added to the "Big Dig" deficit.

The state later took away my license as a site cleanup engineer. The expert witnesses against me at the hearing couldn't cite anything I had done contrary to regulations. but, as the Board's lawyer said, I hadn't been charging my clients enough. Since the Board was mostly my business competitors that was a terrible crime.

As an example, there was an oil spill at a church I had belonged to. Another engineer had estimated $70,000 to explore for contamination. I provided my services pro bono and worked with volunteers from the congregation. We did the job for $600.

The State Board took away my license on the spot, so I retired. My lawyer charged me more than my income for that year and never really understood what was going on.

That sort of thing should explain why I enjoyed the book. I had been trained as a nuclear physicist but I had done a fair amount of engineering work, at least partly because my father was a tool & diemaker. When I worked for the engineering firm anything that didn't fit precisely within one or another specialty was given to me to try. Since I didn't have any preconceived ideas I could sometimes figure out a cheap way to accomplish the task.

Even my Ph.D. thesis was less interesting for the physics it contained than the design of the instrument I did it with. People all over the world were interested in that.

But I'm not in that business any more as you can see from

But if you run across one of Professor Petroski's books, grab it. Even a non-engineer will find it interesting.

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