6CHEN J, SHI Y, SHI S. Noise analysis of digital ultrasonic nondestructive evaluation system. The International Journal of pressure Vessels and Piping, 1999, 76 (9) : 619 -630.
7黄建兵.超声波精确测距的研究[J].南京理工大学学报,2004,(2):11-12.
8BRASSER P, HOSTEN B, VULOVIC F. High frequency transducers and correlation method to Enhance ultrasonic gas flow metering. Flow Measurement and Instrumentation, 2001, 12 (3) : 201 -211.