When the porosity and pore diameter reduced, the sound absorption curve moved to the low frequency zone and the frequencybandwidth 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。
3
The radio provides interoperability and compatibility with IP-based systems and has an extended radio-frequency range and narrow-frequencybandwidth operating modes.