短語詞組短語power r spectral density 功率譜密度power -spectral density psd 功率譜密度the cross -power-spectral method 互功率譜法power spectral density PSD 功率譜密度displacement power spectral density 位移能譜密度power spectral indensity 功率譜密度Power spectral analysis 功率譜分析;譜分析 返回 power spectral