或许你不该来

starkyo

没有无缘无故的爱与恨

starkyo

也没有永久的离与分

君莫笑

天上也会掉馅饼的吧

君莫笑

有时候

君莫笑

很难说的

君莫笑

口水王YOYO

君莫笑

没有，也米有

君莫笑

没什么说的了。

君莫笑

睡觉去吧

starkyo

太没内容了，字数不够应该加到十个字。

U.S.A

听力练习

U.S.A

只灌七层收工

U.S.A

Take a hike. No, literally: join the growing legion of New Yorkers who walk everywhere, for blocks and block and blocks, like the novelist Nicole Krauss or the design aficionado Randy Swearer, who considers his daily eight-mile strolls through the streets of the city better than theater. Need a guide? John Strausbaugh is happy to oblige. He’ll take you on a guided tour of Hell’s Kitchen, still home to glass-crunching circus artists and excellent cheap fried chicken. Step on over.

猛龙过江

又分５ＧＧ，还来灌５下下，，，

U.S.A

Caution Over Shuttle Shows Shift at NASA
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By KENNETH CHANG
Published: August 20, 2007
Confronted with the same kind of problem that doomed the space shuttle Columbia, NASA officials, chastened by years of criticism and upheaval in the agency, took a markedly different approach during the current mission of the Endeavour, calling on an array of new tools and procedures to analyze and respond to the problem.

While the Columbia faced much more serious damage — a 6- to 10-inch hole punched in a wing that let in hot gases during re-entry — outside officials said that with the Endeavour, NASA had taken steps far more elaborate and methodical in concluding that the craft was still safe.

“The comparison is night and day,” said John M. Logsdon, director of the Space Policy Institute at George Washington University, who served on the investigation board that looked into the Columbia disaster. He said he thought NASA had handled the Endeavour situation perfectly.

Engineers and officials with the National Aeronautics and Space Administration will not know how accurate their analysis was or whether their decision to forgo a repair of a gouge in the Endeavour’s underside was the correct one until the shuttle is back on Earth. The landing is scheduled for tomorrow.

But in maneuvers as simple as having the Endeavour perform a slow back flip to allow the crew aboard the International Space Station to photograph the shuttle’s belly, to the use of a new laser scanner that showed the exact shape and size of the damage, NASA officials demonstrated the vast changes in procedures, attitude and culture of the agency since the Columbia accident four years ago.

In both missions, a piece of foam fell from the fuel tank, damaging the shuttle; both times, NASA officials expressed confidence that there would be no peril to spacecraft or crew.

But this time, there is better reason to believe the assurances, outside experts say. For one, the piece of foam that hit the Endeavour was much smaller. And the accident, and the investigation board’s call for a transformation in the safety culture of NASA, led to changes within the agency.

The head of the shuttle program retired and the mission management team leader transferred out of the shuttle program. New tools were developed to identify and analyze damage to the heat tiles, and senior managers began to make sure that dissenting voices could be heard.

Perhaps the Endeavour analysis overlooked some crucial detail, but that possibility is “very, very slight,” Dr. Logsdon said. “This episode is a good example of how the shuttle program has changed.”

For both the Columbia and the Endeavour, the falling foam did not initially worry mission managers. The day after the Endeavour’s liftoff, John Shannon, chairman of the mission management team, said that three small pieces of foam might have hit, but “nothing significant.”

What changed in the last four years is how NASA managers handle an event they do not consider serious. Michael D. Griffin, the NASA administrator, said he and managers listened to all of the data before making decisions.

The Columbia’s mission mangers never thought foam could cause catastrophic damage, and subsequent analysis was performed in a way to back up that conclusion. They quashed requests to have spy satellites take a closer look at the underbelly of the Columbia, so they never knew where the 1.67-pound piece of foam hit the orbiter.

The engineers dismissed, without detailed analysis, the possibility of damage to the leading edge of the Columbia’s wings from foam.

Reconstruction of the Columbia’s debris showed that the foam, hurtling at 500 miles per hour, punched a hole 6 to 10 inches wide, which allowed hot gases to enter the wing during re-entry.

“What we uncovered was a relatively cavalier attitude to the damage of the thermal protection system,” said G. Scott Hubbard, another member of the Columbia accident investigation board who is now a professor of aeronautics and astronautics at Stanford.

That board found that a “broken safety culture” was as much a cause of the accident as the piece of insulating foam that struck the shuttle. John Allmen, program manager for shuttle support at the NASA Ames Research Center, said the pre-Columbia culture of NASA was sometimes intimidating for an engineer to bring up a concern. “The general culture was that, ‘What are you talking about? Prove to me it will fail,’ ” he said.

Mr. Allmen said he still occasionally saw signs of the old culture, but that the top officials like N. Wayne Hale Jr., the shuttle program manager, push it aside. “He says, ‘We’re going to talk about it,’ ” Mr. Allmen said. “He keeps a very open and very detailed format for discussion and comments.”

This time, mission managers knew the exact damage caused by the foam, which weighed one-third of an ounce. As the Endeavour approached the space station and performed the back flip, the station crew pinpointed a three-inch gouge on the right wing about four feet behind the landing gear door.

The Endeavour astronauts then used an instrument boom attached to the shuttle’s robotic arm to get a better look at the damage. A laser scanner in the boom, designed and built in response to the Columbia disaster to conduct inspections of the shuttle’s underside, provided the exact shape and size of the gouge.

Then engineers performed detailed computer simulations to predict what the flow of hot gases during re-entry would do to the damaged area. The simulations indicated that the hottest gases would not flow to the bottom of the gouge and that the temperatures of the underlying aluminum skin would remain safe.

That work was conducted by engineers from the Ames Research Center, who had adapted existing computer programs for the space shuttle, and then checked by other engineers from the Langley Research Center.

Engineers from the NASA research centers had not been involved during shuttle flights before the Columbia. About 100 people worked on the analysis of the Endeavour gouge.

In the mission management meetings, engineers reviewed the data and all agreed that the gouge did not pose a threat. As an extra caution, engineers analyzed what would happen if they were wrong and some of the aluminum structure above the damaged area was lost. Even then the Endeavour would return safely, they concluded.