working channel
3.The working principle of a multi-channel ultrasonic inner inspection pig and the design scheme of its subsystems are introduced, the principle block diagram is presented, and many methods such as synchronous collection and memory of thickness data and orientation data are put forward.
7.The paper presents a kind of multi-channel quasi-square-wave Synchronous Rectifying Buck(SR-Buck) converter for the lower-voltage high current power system,and analyzes its working principles in detail.
10.The system uses PC and single-control dual mode to control the temperature separately and uses DS1620 to collect four-channel temperature with MPU and PC serial communication. PC could control the working temperature of X-ray collection board through semiconductor refrigeration chip.

