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磁  悬  浮  列  车

磁悬浮列车是由无接触的电磁悬浮、导向和驱动系统组成的新型交通工具,是高新技术的产物。上海磁悬浮列车示范运营线项目于2006年4月26日正式通过国家竣工验收。正线全长约30km,设计最高运行时速430km/h,单向运行时间7min20s。

(1)上海磁悬浮列车的结构如图甲所示.要使列车悬浮起来,车身线圈的上端是_________极,它是利用_____________的相互作用,将车身托离轨道,大大减小了___________,使列车能高速运行。若列车总质量是20t,磁悬浮列车行驶时,强大的___________使列车上升10mm。 

(2)如果列车在单向运行过程中,只停靠一站,那么,停靠时间约为_________(设磁悬浮列车全程均以360km/h的速度行驶)。

(3)图乙是另一种磁悬浮列车的设计原理图,A是磁性稳定的电磁铁,安装在铁轨上,B是安装在车身上(紧靠铁轨上方)的电阻非常小的螺线管。B中电流方向如图乙所示,请在图中标出通电螺线管的N极,螺线管B与电磁铁A之间相互_________ (选填“排斥”或“吸引”),从而使列车悬浮在铁轨上方。

答案

(1)北  同名磁极互相排斥  摩擦  斥力(排斥力)  

(2)2min20s  

(3)B的下端是S极  排斥

阅读理解

B

WASHINGTON – It’s a great achievement that inspires notions of robots with consciousness and independent minds.

When people or animals get hurt, they can usually compensate for minor injuries and keep limping along, but for robots, even slight damage can make them stumble and fall. However, a recently made robot has demonstrated a novel ability: it can heal its own damage.

The new robot, which looks like a splay – legged, four – footed starfish can sense injury to itself and adapt. That ability sets the new robot apart from earlier machines. Because the robot can recover from unfamiliar places. “There is a need for planetary robotic rovers to be able to fix things on their own,” says Josh Bongard, a professor in the University of Vermont, who is one of the device’s creator. “Robots on other planets must be able to continue their mission without human help if they are damaged and cannot communicate their problem back to Earth.”

A typical robot functions according to a computer program, but the new robot works differently. First, sensors in its four legs observe the robot’s movements and signals to its built – in computer. From the formation it collects, the robot creates its own programs that allow it to adapt to different situations. For example, when the researchers shortened one of the robot’s legs, the smart machine simply adjusted its way of walking – it used three legs instead of four.

The researchers are looking for other places to put the resilient robot to work. One pellicle spot is the ocean floor. That dark and dangerous undersea terrain might be a good choice for a robot the scientists call the Starfish. “We never officially named the robot, but we usually refer to it as the Starfish, even though a real starfish has five rather than four legs,” says Bongard. “Also, a real starfish  is much better than our robot at recovering from injury, because it can actually grow its legs again.” Scientists have created robots that help humans in many ways: by exploring space, fighting fires, and even performing surgery.

46.The newly designed robot distinguishes itself from the former ones because it___________

A.can communicate with people on the earth about their problems

B.works according to a certain computer program

C.can find its problems and solve them automatically

D.can explore unfamiliar places

47.An example is given in the fourth paragraph in order to explain that the robot ___________

A.is used to create new programs

B.has typical robot functions

C.has sensors to observe its movements

D.can gather information and adapt to new conditions

48.The underlined word “resilient” in the last paragraph means the robot is ___________.

A.creative    B.newly made     C.able to recover    D.informative

49.Which of the following is TURE about the robot “Starfish”?

A.It was spoken highly of by people for its special ability?

B.It will stumble and fall if damaged.

C.It can grow its legs again once they are broken.

D.It has started to work on the ocean floor.

50.What might be the best title of the passage?

A.How does the Starfish Robot work

B.Do – It – Yourself Robot Repair

C.Robots Designed to Work On Other Planets

D.New Robot Helping Us In Many Ways

单项选择题