The propagation of P-wave in one-dimensional rock masses is analyzed according to plane to plane contact model.

采用面-面接触模型模拟了纵波在一维岩体中的传播，给出了纵波波形；

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So it indicates that the surface with this kind of concave can reduce friction under the condition of plane-plane contact, and if the concave on the surface has some special depth t...

从而得到结论，在平面-平面接触，乏油状态下，该种表面凹坑有一定减阻作用，且在某一深度的凹坑减阻效果最好。

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The key to Silent Feet is slowly and simultaneously to contact the wall’s vertical plane and the foothold’s horizontal aspect — so visually track the movement.

幽灵步的关键是要缓慢且自然的接触岩壁的垂直面以及脚点的水平面 所以需要用目光来注视着脚的移动。

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But air traffic controllers say they lost contact with the Twin Otter plane.

VOA: standard.2009.08.02

Fighter pilots were sent up to intercept Stewart's plane after controllers lost contact with it, and they reported its cockpit and cabin windows were frosted over.

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Air traffic controllers re-established radio contact after the plane had flown about 150 miles past its destination.

CNN: Crew of wayward airliner cooperative, sober, police say

Shortly afterward, air traffic controllers in Malaysia lost contact with the plane somewhere over the sea between Malaysia and Vietnam.

CNN: Pilot spots large object off Reunion Island