To detect water leaking of underground tube, the traditional method relies on the sound-electricity transformation. Therefore, detection sensitivity, depth and distance suffer great limitation.
传统的检测地下管道漏水的方法是以声—电转换为基础，这使得灵敏度、深度和距离都受到很大限制。
2
Tube too much, will only let the distance more and more far.
管的太多，只会让距离越来越远。
3
This system was used to measure the flame propagation velocities along the tube, and furthermore to determine the DDT distance.