.燕京理工学院YANCHING INSTITUTE OF TECHNOLOGY 外文文献原稿和译文学院：机电工程学院专业：机械工程学号：130310208姓名： 张磊指导教师：王续明2017 年 3 月外文文献原稿和译文原 稿The water supply system is the national production and life indispensable important one annulus. The traditional method of water supply area, water pollution, infrastructure investment, but the main drawback is that water can not be kept constant, causing part of the equipment can not work normally. Variable frequency speed cont
