摘要
通过研究超声波声场的指向性及近场区声压的轴向变化规律,得出如下结论:在木材超声波衰减成像中,当工作频率为15 kHz时,声轴线上的观测点均位于声场较稳定的远场区,可以将接收端的振幅看作只与粘滞性衰减有关而不做调整;而声轴线外的观测点受非粘滞性因素的影响较大,需要对振幅进行方向性校正,并给出校正的计算方法。
By studying the ultrasonic field directivity and axial changes of sound pressure in near field region, the results obtained showed that when the working frequency was 15 kHz, the observation points on the beam axis all located in the far field region of relatively stable sound field. Consequently, the amplitude of the receiver could be regarded to be related to viscous attenuation without adjustment. Nevertheless, the observation points out of the beam axis were heavily affected by the non-viscosity factors, as a result of which, directional correction to amplitude was needed and the correction method was introduced.
出处
《森林工程》
2009年第3期60-62,65,共4页
Forest Engineering
基金
国家"十一五"科技支撑课题(2006BAD18B07)资助
国家自然科学基金项目资助(30671643)
关键词
超声波
接受方向角
振幅
声场
ultrasonic
receiving direction angle
amplitude
sound field
