An electric line of force is also a closedline; it too forms a loop and returns on itself.
电力线也是一条封闭线;它形成一个圈,返回原处。
2
The system had many features such as high speed, high accuracy, untouched measuring and closed-loop control. The system is used on-line measuring and control of diameter measure.
The on-line application in Fujian Refinery shows that the model has a satisfactory accuracy, and it can be used for closed-loop control and optimal operation.