valve-opening period

The result shows that the defrosting period of machine with electronic expansion valve is 12 seconds or 11% shorter than that with thermal expansion electronic valve, so suggests integrating both two methods by using the electronic expansion valve and defrosting by reversing four-way valve with compressor off.

结果表明：采用电子膨胀阀的除霜时间比热力膨胀阀的短12s，即减少11%。

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The management of severe heart valve disease at perioperative period

重症心脏瓣膜病围手术期处理

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The tappet clearance is slightly effective to distortion only during the valve lifting period if it changes not much from designed value.

气门间隙在设计值附近变化不大时，仅在气门开启阶段对配气机构动变形稍有影响。

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LPR N testing valve is the main valve for testing drill stem of APR tools, of which the key role is to make true the close and open of well during testing period.

LPR N测试阀是APR工具测试管柱的主阀。其主要作用是实现测试中的开关井。

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