Download PDF by : [Magazine] Scientific American. Vol. 272. No 3

Read or Download [Magazine] Scientific American. Vol. 272. No 3 PDF

Best nonfiction_3 books

Download e-book for kindle: Large-scale scientific computing, 7 conf., LSSC 2009, by

This e-book constitutes the completely refereed post-conference lawsuits of the seventh foreign convention on Large-Scale clinical Computations, LSSC 2009, held in Sozopol, Bulgaria, in June 2009. The ninety three revised complete papers awarded including five plenary and invited papers have been rigorously reviewed and chosen from a variety of submissions for inclusion within the booklet.

Additional resources for [Magazine] Scientific American. Vol. 272. No 3

Sample text

Meyers recalls one proposerally does), animal testing and fixed al for a study of gene therapy for canR&D costs. He also adds “opportunity cer in which investigators offered to cost”: the profit that could have been alter the DNA of bone marrow cells made by investing drug development free of charge as long as patients dollars elsewhere. Opportunity costs paid the $200,000 needed to have account for approximately half of his the cells extracted and reimplanted. figure, DiMasi says. At one time, insurance companies Regardless of whose number is covered parts of experimental theracloser, drug companies definitely do pies, but lately they have shied away abandon some compounds for lack from paying charges that patients reof a market rather than lack of thera- ceiving ordinary treatment would not peutic promise, DiMasi says.

Trick of the Tail T he coincidence of high thrust and eÛciency is not the only advantage of a ßapping foil. It also oÝers the possibilities of more ßexible operation, more maneuverability and, most intriguingly, tempting opportunities for recapturing kinetic energy from a wake. Fish instinctively exert precise and eÝective control of the ßow around their bodies to extract energy from waves, turbulence and even their own wakes. They have also evolved ways of controlling the ßow so as to enhance their turning and starting.

These results show that the criteria that indicate a stall for Þxed wings do not apply to a ßapping foil. True, what causes a stall in both cases is the sudden formation of uncontrolled vorticesÑabove and behind the wings, in the case of aircraft, disrupting the normally smooth ßow over them. With the ßapping foil, however, vortices do not in and of themselves cause a stall. In fact, vorticesÑproperly controlled and arrangedÑare essential to a foilÕs eÛcient operation, so it should be no surprise that they can be controlled over a wider range of angles to produce useful thrust.

Download PDF sample

[Magazine] Scientific American. Vol. 272. No 3


by Charles
4.1

Rated 4.78 of 5 – based on 32 votes