rank stage meaning in English

煤级阶段

For vibration mode - shape , this affect is more severity on high rank stage vibration than low . with opened hollow and pier added on dam , the frequency of vibration decline . although the array of low rank vibration mode - shape is changed , the dynamic characteristic of the dam not in evidence change
对于振型而言，这种影响对低阶振型比高阶振型大，考虑孔口和闸墩后，大坝的自振频率有所降低；在低阶振型中有一部分的排列顺序(大小关系)发生了变化，但这些变化不致使大坝的动力特性发生显著的改变。
Through investigating by use of correspondence analysis method , it was proved that the coal facies is the main control factor affecting pore system differential development of the coal reservoirs at high - rank stage in the basin and the high - rank coal has caused a common character of disadvantaging the coalbed methane ' s being produced from the pore system in the coal reservoirs overall
应用对应分析方法发现煤相是该盆地煤储层孔隙系统在高煤层级阶段差异发育的主导控制因素，而高煤级造就了该盆地煤储层孔隙系统总体上不利于煤层气产出的共同特征。