手工操作或用电动工具或机器进行测量，切割，弯曲和穿透管道。
Measure, cut, bend and thread pipes using hand and power tools or machines.
本文讨论了管道流体瞬变过程中压力波在管道中阀门处的穿透和反射情况，导出了压力波在阀门处的穿透和射反系数。
The pressure wave penetration and reflection properitics at a valve, which is located in a conduit, are discussed, And the Penetration and reflection coefficients are derived.
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