经济学的

This paper designs one kind of mineshaft portable gas detector in view of the present situation, when the gas gas density approaches the dangerous value, automatically sends out reports to the police, the reminder mineshaft personnel leaves immediately.

本文针对目前情况设计一种井下便携式瓦斯探测器，当瓦斯气体浓度接近危险值时，自动发出报警，提醒井下人员立刻离开。

Through the introduction of the internal structure of sliding valve in screw rod compressor,the methods of dealing with the problems in controlling the energy level of compressor were indicated.

通过介绍螺杆压缩机的滑阀的内部结构，处理压缩机能级控制出现的问题。