These characteristics made its running process are unacted on external environment hard to damage and using long time . ( 4 ) Wireless automatic reading system .

这些特点使其运行过程中不 易 受 外界环境的 影响， 且 不易损坏，使用寿命长。（4）无线自动抄表。

Are scalar particles and photons unacted directly by torsion

挠 率 场对标量粒子及光子的直接作用 毫 不存在 吗

Ultrasonic is unacted on the light color electromagnetic radiation and so on and can adapt to the severe environment . So nondestructive testing ( NDT ) technologies based on ultrasonic are more and more popular the ultrasonic ranging technology is one of them .

超声波不 受光线、色彩、电磁干扰等影响，能适应较恶劣的环境，所以基于超声波的无损检测（简称NDT）越来越受到人们的关注，超声波测距就是其中之一。

Ultrasonic sensor is the non-contact measuring ; its measurement process is unacted by impurity chemical substances and magnetic materials . It can install horizontal or vertical by low pressure loss .

超声波传感器属于 间接非接触式测量，其测量过程完全 不 受 介质中杂质、化学物质和磁性材料的 影响，压损小，可以水平或垂直安装。