前者称为微分算子的谱分析，后者称为逆谱问题。

The former is called the spectra analysis of a differential operator and the latter is the inverse spectra problem.

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本文采用自功率谱、逆频谱方法对拖拉机变速箱异常噪声源进行了诊断，找出了产生异常噪声的根源。

With auto-power spectrum and cepstrum, this paper diagnoses the unusual noise source of the gear box, and finds an impaired gear of the box.

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本文采用频响函数矩阵求逆法，辨识了立式机组动态力的幅值谱。

By using inverse matrix of frequency response function in this paper, the spectrum of dynamic forces acting on the set has been identified.

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