卫生类AB级:阅读理解Pool Watch
Swimmers can drown in busy swimming pools when lifeguards fail to notice that they are in trouble. A report says that on average 15 people drown in British pools each year， but many more suffer major injury after getting into difficulties. Now a French company has developed an artificial intelligence system called Poseidon that sounds the alarm when it sees someone in danger of drowning.
When a swimmer sinks towards the bottom of the pool， the new system sends an alarm signal to a poolside monitoring station and a lifeguard‘s pager (呼机)。 In trials at a pool in Ancenis， near Nantes， it saved a life within just a few months， says Alistair McQuade， a spokesman for its maker， Poseidon Technologies.
Poseidon keeps watch through a network of underwater and overhead video cameras. AI software analyses the images to work out swimmers‘ trajectories (轨迹)。 To do this reliably， it has to tell the difference between a swimmer and the shadow of someone being cast onto the bottom or side of the pool.
It does the same with an image from another camera viewing the shape from a different angle. If the two projections are in the same position， the shape is identified as a shadow and is ignored. But if they are different， the shape is a swimmer and so the system follows its trajectory.
To pick out potential drowning victims， anyone in the water who starts to descend slowly is added to the software‘s “pre-alert” (预先警戒) list， says McQuade. Swimmers who then stay immobile on the pool bottom for 5 seconds or more are considered in danger of drowning. Poseidon double-checks that the image really is of a swimmer， not a shadow， by seeing whether it obscures (使模糊) the pool’s floor texture when viewed from overhead. If so， it alerts the lifeguard， showing the swimmer‘s location on a poolside screen.
The first full-scale Poseidon system will be officially opened next week at a pool in High Wycombe， Buckinghamshire. One man who is impressed with the idea is Travor Baylis， inventor of the clockwork (时钟装置) radio. Baylis runs a company that installs swimming pools - and he was once an underwater escapologist (脱身杂技演员) with a circus (马戏团)。 “1 say full marks to them if this works and can save lives，” he says.
11 AI means the same as
A an image.
B an idea.
C anything immobile.
D artificial intelligence
12 To save a life， AI software must be able to
A descend in the water.
B videotape every movement.
C distinguish between a swimmer and a shadow
D save a life within a few months.
13 How does Poseidon save a life?
A It orders an underwater robot to rescue the drowning swimmer.
B It alerts the lifeguard.
C It displays the swimmer‘s shadow on the screen.
D It watches the pool through dozens of overhead cameras.
14 Which of the following statements about Travor Baylis is NOT true?
A He owns a swimming pool.
B He invented the clockwork radio.
C He was once an entertainer.
D He runs a company.
15 How does Baylis look at the Poseidon system?
A He thinks it is too expensive.
B He thinks it is a good system.
C He thinks it is not efficient enough.
D He thinks it is as good as the British pool Watch system.
答案：A C D B B
