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mitree's world
design, photography, video, animaiton, internet, flash
Browsing mitree's world blog archives for August, 2010.
A giant hole in Guatemala swallowed more than ten houses on Friday. This huge sinkhole is said to be more than 100 meter (330 feet) deep, it’s located in a poor district of Guatemala City.
Residents say the big hole suddenly appeared. The earth started shaking and loud noises were heard, several houses collapsed into the sink hole but no one got hurt. Locals say the air which arose from the hole smelled bad, just like a sewer.
Initially, a man and two teens were missing but according to BBC News they turned up later.
According to Guatemala City officials the hole was caused by leaking sewer pipes, which eroded the earth.
Guatemala City’s major Alvaro Arzu says the sewers will be repaired and help will be offered to those affected.
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» https://www.cia.gov/library/publications/the-world-factbook/geos/pc.html
Pitcairn Island was discovered in 1767 by the British and settled in 1790 by the Bounty mutineers and their Tahitian companions. Pitcairn was the first Pacific island to become a British colony (in 1838) and today remains the last vestige of that empire in the South Pacific. Outmigration, primarily to New Zealand, has thinned the population from a peak of 233 in 1937 to less than 50 today.
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» http://www.mindfully.org/Health/Space-Survival-NG1jan01.htm
Three days on the moon in the final Apollo mission, in 1972, leave astronaut Eugene Cernan weary and filthy with rock dust. A three-year trip to Mars multiplies the hazards of space travel, confronting NASA with a troubling scenario. Imagine a radiation-sick, sleep-deprived astronaut stepping on Mars. Muscle-and-bone-weakened, immune-system-challenged, he faints and breaks a leg. What now, Houston?
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» http://en.wikipedia.org/wiki/Busemann%27s_Biplane
Busemann’s Biplane is a conceptual airframe design invented by Adolf Busemannwhich inherently prohibits the formation of N-type shock waves and thus does not create a sonic boom.
It consists of two triangular cross-section plates a certain distance apart, with the flat sides parallel to the fluid flow. The spacing between the plates is sufficiently large that the flow does not choke and supersonic flow is maintained between them.
Usually with supersonic flow a positive pressure shock wave is generated at the front and a negative pressure shock wave at the rear. In Busemann’s biplane, the high pressure shock wave is created internally and reflects symmetrically between the two plates. This cancels/fills the expansion fan forming at the rear, leaving no external shock waves to propagate to infinity. The flat upper and lower surfaces generate no shock waves because the flow is parallel.
The internal alignment of the shock waves means that Busemann’s Biplane produces minimum wave drag[1]. However, the flat external surfaces and internal symmetry also mean that the airfoil does not produce any lift. Hence, no implementation has yet flown, although the concept has been successfully tested in wind tunnels and for ammunition.
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