短語詞組短語power r spectral density 功率譜密度power -spectral density psd 功率譜密度power spectral density PSD 功率譜密度displacement power spectral density 位移能譜密度auto power spectral density 自功率譜wave power spectral density 波能波密度power spectral density technique 功率譜密度技術geometric power spectral density 幾何功率譜密度power spectral density analyze 功率譜分析儀 返回 power spectral density