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发帖数: 6973 | 1 Kris Maher, New Tool May Reach Trapped Miners;
Lockheed Martin Is Testing Wireless Communication System to Help Locate
Workers After Accidents
Wall Street Journal, July 20, 2010.
http://online.wsj.com/article/SB10001424052748704720004575377232010729558.html
("to send a fully wireless signal through the layers of earth and rock above
mines. * * * Using the magnetic waves, the system has successfully
transmitted signals through mines to depths in excess of 1,550 feet in tests
. Radio waves, by con |
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