The motor on the spot is in operation in the random failure period and therefore its failure rate is approximately a constant.
现场使用的电机基本运行在偶然失效阶段，因而其失效率近似为一常数。
2
When concentration of toluene was constant, the lag period of TCE increased, and the rate and extent of degradation decreased with the concentration of TCE increasing.
The pattern of the progressive evolution of offset streams might indicate that the slip rate of the fault in the same place is relatively constant during a certain period.