衛生類AB級:閱讀理解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 (呼機)。 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 (軌跡)。 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” (預先警戒) 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 (時鐘裝置) radio. Baylis runs a company that installs swimming pools - and he was once an underwater escapologist (脫身雜技演員) with a circus (馬戲團)。 “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