2014英语四级听力练习慢速4.19(1)_大学英语听力

2014英语四级听力练习慢速4.19(1)

　　Earlier this year, Homeland Security and rescuers used FINDER to carry out more than 65 test searches in the American state of Virginia.

　　They say the tests proved successful in recognizing a human heartbeat under nine meters of mixed concrete and other material. The device was also able to identify a heartbeat hidden behind six meters of solid concrete, and from a distance of up to 30 meters in open space.

　　Jim Lux is with the Jet Propulsion Laboratory in California.

　　FINDER works by sending a low-power microwave signal, and it illuminates the rubble pile, and some of the microwaves go in and reflect off the victim inside and come back out. So FINDER sees both the reflection from the rubble, which doesnt move, and a very tiny reflection from the victim, which does move, because when you breathe and when your heart beats, your skin moves a little bit and we can see that.

　　Jim Lux says the device is small, easy to carry and easy to use.

　　It goes out and collects 30-seconds worth of data, because that is how long you need to get the heartbeat and the breathing, and then it analyzes it and displays it for the user.

　　FINDER could be used with other tools rescuers use, such as listening devices or search dogs. Matthew Tamillow is with Virginia Task Force 1. He says the new technology could help rescuers in deciding which buildings to search.