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The 'snap' that spells danger

发布时间:2019-03-02 03:03:01来源:未知点击:

By Barry Fox Faint snapping noises can give early warning of weakness in a suspension bridge, say Peter Paulson and John McIntyre of Calgary, Alberta. But the sounds are too faint to hear, so the pair have come up with a way to listen for them (US patent 2004/143397). A suspension bridge’s cables contain thick bundles of thin wires, several hundred metres long. Piezoelectric microphones are stuck to the cables at the anchor points at each end, and to the support towers near where the cables run over the tops. If a strand of wire inside a bundle snaps,