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电流互感器的选择和校验。 电流互感器一次电流变化的大小对误差的影响，说法正确的是( )。
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In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civilization from the faces of terror". The company’s share price skyrocketed, as did the stocks of other face-recognition companies, and airports across the globe began installing the software and running trials. As the results start to come in, however, the gloss (光滑表面) is wearing off. No matter what you might have heard about face-recognition software, Big Brother it ain’t. The concern was based largely on an independent assessment of face-recognition systems carried out in 2000 in the U. S. by the Department of Defense. These tests found that to catch 90 per cent of suspects at an airport, face-recognition software would have to raise a huge number of false alarms. One in three people would end up being dragged out of the line and that’s assuming everyone looks straight at the camera and makes no effort to disguise himself. Results from the recent airport trials would seem to justify that concern. Most face-recognition systems use some kind of geometric technique to translate a picture of a face into a set of numbers that capture its characteristics. Once it has identified these boundaries, the software calculates their relative sizes and positions and converts this geometry into what Visionics calls a "faceprint". Feed the software a series of mug-shots (通缉犯), and it’ll calculate their faceprints. Then it can monitor live CCTV images for the faces of known suspects. When it finds a match, it raises an alarm. Even if the system does manage to capture a face, the problems aren’t over. The trouble is that a suspect’s faceprint taken from live CCTV is unlikely to match the one in the database in every detail. To give themselves the best chance of picking up suspects, operators can set the software so that it doesn’t have to make an exact match before it raises the alarm. But there’s a price to pay: the more potential suspects you pick up, the more false alarms you get. You have to get the balance just right. Despite the disappointing tests, some people insist that face-recognition technology is good enough to put terrorists off. After all the claims and counter-claims, with no one able to discern (洞察) the truth, the industry may soon have to face up to reality. What makes it so hard for the face-recognition systems to work effectively
In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civilization from the faces of terror". The company’s share price skyrocketed, as did the stocks of other face-recognition companies, and airports across the globe began installing the software and running trials. As the results start to come in, however, the gloss (光滑表面) is wearing off. No matter what you might have heard about face-recognition software, Big Brother it ain’t. The concern was based largely on an independent assessment of face-recognition systems carried out in 2000 in the U. S. by the Department of Defense. These tests found that to catch 90 per cent of suspects at an airport, face-recognition software would have to raise a huge number of false alarms. One in three people would end up being dragged out of the line and that’s assuming everyone looks straight at the camera and makes no effort to disguise himself. Results from the recent airport trials would seem to justify that concern. Most face-recognition systems use some kind of geometric technique to translate a picture of a face into a set of numbers that capture its characteristics. Once it has identified these boundaries, the software calculates their relative sizes and positions and converts this geometry into what Visionics calls a "faceprint". Feed the software a series of mug-shots (通缉犯), and it’ll calculate their faceprints. Then it can monitor live CCTV images for the faces of known suspects. When it finds a match, it raises an alarm. Even if the system does manage to capture a face, the problems aren’t over. The trouble is that a suspect’s faceprint taken from live CCTV is unlikely to match the one in the database in every detail. To give themselves the best chance of picking up suspects, operators can set the software so that it doesn’t have to make an exact match before it raises the alarm. But there’s a price to pay: the more potential suspects you pick up, the more false alarms you get. You have to get the balance just right. Despite the disappointing tests, some people insist that face-recognition technology is good enough to put terrorists off. After all the claims and counter-claims, with no one able to discern (洞察) the truth, the industry may soon have to face up to reality. What is the fatal defect of the system according to the U. S. Department of Defense
Human beings are animals. We breathe, eat and digest, and reproduce the same life (21) common to all animals. In a biological laboratory rats, monkeys, and humans seem very much the same. However, biological understanding is not enough: (22) itself, it can never tell us what human beings are. (23) to our physical equipment the naked human body--we are not an (24) animal. We are tropical creatures, (25) hairless and sensitive to cold. We are not fast and have neither claws nor sharp teeth to defend ourselves. We need a lot of food but have almost no physical equipment to help us get it. In the purely physical (26) , our species seems a poor (27) for survival. But we have survived--survived and multiplied and (28) the earth. Some day we will have a (29) living on the moon, a place with neither air nor water and with temperatures that turn gases into solids. How can we have done all these things Part of the answer is physical. (30) its limitations, our physical equipment has some important (31) . We have excellent vision and hands that can (30) objects with a precision unmatched by any other (33) . Most importantly, we have a large brain with an almost (34) number of neural (35) .
Before high school teacher Kimberly Rugh got down to business at the start of a recent school week, she joked with her students about how she’d had to clean cake out of the corners of her house after her 2-year-old son’s birthday party. This friendly combination of chitchat took place not in front of a blackboard but in an E-mail message that Rugh sent to the 145 students she’s teaching at the Florida Virtual School, one of the nation’s leading online high schools. The school’s motto is "any time, any place, any path, any pace". Florida’s E-school attracts many students who need flexible scheduling, from young tennis stars and young musicians to brothers Tobias and Tyler Heeb, who take turns working on the computer while helping out with their family’s clam-farming business on Pine Island, off Florida’s southwest coast. Home-schoolers also are well represented. Most students live in Florida, but 55 hail from West Virginia, where a severe teacher shortage makes it hard for many students to take advanced classes. Seven kids from Texas and four from Shanghai round out the student body. The great majority of Florida Virtual Schooler-- 80 percent are enrolled in regular Florida public or private high schools. Some are busy overachievers. Others are retaking classes they barely passed the first time, The school’s biggest challenge is making sure that students aren’t left to sink or swim on their own. After the school experienced a disappointing course completion rate of just 50 percent in its early years, Executive Director Julie Young made a priority out of what she calls "relationship-building," asking teachers to stay in frequent E-mail and phone contact with their students. That personal touch has helped: The completion rate is now 80 percent. Critics of online classes say that while they may have a limited place, they are a poor substitute for the face-to-face contact and socialization that take place in brick-and-mortar classrooms. Despite opportunities for online chats, some virtual students say they’d prefer to have more interaction with their peers. Students and parents are quick to acknowledge that virtual schooling isn’t for everyone. "If your child’s not focused and motivated, I can only imagine it would be a nightmare," says Patricia Haygood of Orlando, whose two daughters are thriving at the Florida school. For those who have what it takes, however, virtual learning fills an important niche. "I can work at my own pace, on my own time," says Hackney. "It’s the ultimate in Student responsibility.\ "Any time, any place, any path, any pace" is ______.
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