random drafts meaning in English

不规则牵伸
任意牵伸

Based on some problems about random draft , energy conservation and ensemble efficiency of hydraulic - projects utilization , by the way of full - scale test , the application of frequency changer in agricultural water saving have been studied . it is the first time in china for the imagination that frequency changer has been used in tube - well irrigation in order to make the water pump keep constant transformation
本项目针对目前农业节水灌溉工程中存在的随机取水、节能问题和水利工程资源的综合利用效率提高问题，以实地工程应用试验为基础，对变频调速装置在农业节水灌溉工程中的应用进行了研究。