PWR的压力释放装置主要有四种类型：直接作用式安全阀、先导操作压力释放阀、动力作用式压力释放阀和具有辅助装置的安全阀。
There are four types for PWR pressure-relieving devices: direct acting safety valve, pilot-operated pressure relief valve, power-operated pressure relief valve and safety valve with auxiliaries.
在旅游接待工作中，许多工作都必须靠员工手工操作，而且需要面对客人提供富有人情味的直接服务，因而需要大量的劳动力。
Manual service is needed in many tasks in tourist reception, and the customers should be provided with direct and personal service, this makes necessary large number of labor force in the industry.
锻造操作手在时变工况下的动力学特性直接影响着锻件的成形质量。
The quality of forging has a direct relation with the dynamic performance of forging manipulators in time-varying conditions.
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