共用题干
第三篇
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.
Al 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）."I say full marks to them if this works and can save lives,"he says.
Al means the same as
A:an image.
B:an idea.
C:anything immobile.
D:artificial intelligence.

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