Ultrasonicemission is a phenomenon with cavitation of vessels or tracheids.
植物的超声发射是导管或管胞里空穴化时的伴随现象。
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The characteristic of linear and nonlinear responses between arc excited ultrasonicemission and excited frequency was realized by the received signal from the acoustic to the ultrasonic spectrum.
The basic theory in designing and implementing the ultrasonic distance measuring system, is to record the time between the emission wave and the reflected wave by the object.