【单选题】406MHZ EPIRB自浮式支架的静水压力释放器的使用时间限制是_
【多选题】中国古代建筑以木构架结构为主要的结构方式,创造了与这种结构相适应的各种( )。
【单选题】406MHz EPIRB自浮式支架的静水压力释放器的使用年限是()。
【多选题】离心压缩机的喘振Second, the centrifugal compressor surge:()
A.
现象:压力、流量大幅度变化;吼叫;振动强烈。 Phenomenon: pressure and flow change greatly; Roar; The vibration is strong.
B.
危害harm:强烈振动破坏密封部件及轴承、叶轮等运转部件。Strong vibration damages sealing parts and bearing, impeller and other running parts.
C.
防止方法prevention method:保证Q1>Qmin,工作点压力低于喘振点压力。Ensure Q1>Qmin, working point pressure is lower than surge point pressure.
D.
防止方法prevention method:当Q1
【单选题】世界上第一家商业性旅行社诞生于( )年。
【单选题】中国古代建筑以( )结构为主要的结构方式。
【单选题】【2017年真题·单选】世界上第一家商业性旅行社诞生于( )。
【多选题】采用高强钢的优势有以下几方面The advantages of using high strength steel are as follows:()
A.
输量一定,高压输送,管径减小,厚度减小,用 量减少With a certain amount of transportation, the pipe diameter is reduced, the thickness is reduced and the quantity is reduced;
B.
管径与重量减小,施工费用减少Reducing pipe diameter and weight and construction cost;
C.
输送压力提高,压缩机站间距增大,同时天然气 密度大,压缩机效率提高,能耗减小The transportation pressure increases, the compressor station spacing increases, at the same time, the natural gas density increases, the compressor efficiency increases, and the energy consumption decreases.