When the porosity and pore diameter reduced, the sound absorption curve moved to the low frequencyzone and the frequency bandwidth increased at the same time.
随着孔隙率、孔径的减小，多孔铝的共振吸声系数有所下降，吸声频谱曲线向低频方向移动，且频带宽度展宽。
2
It shows in theory that the frequency domain sounding in near zone of the line current source is possible.
通过对计算结果的分析，在理论上说明了线源频率域近区测深的可行性。
3
The EB scanning track, scanning frequency and energy density distribution at heating zone could be programmed off-line and adjusted on-line.