The adding system regards the slime water of the freedistrict of the thickener as detecting target, sedimental speed as the feedback, form the close-circuit control system.
该添加系统以浓缩池自由区的煤泥水为检测对象，以沉降速度作为反馈量，构成闭环控制系统。
2
UCCA, located at 798 art district, also offers a free art workshop every weekend for children of migrant workers in the capital.
尤伦斯当代艺术中心(UCCA)位于798艺术区，每周还为首都的外来工儿童提供免费的艺术工作室。
3
Under the program, the district gives home-schooling families free computers and Internet service for correspondence classes.