本文主要利用非參數化方法於頻譜估測之模態參數識別。在頻域分析中，大部分的量測訊號透過快速傅立葉轉換，將時間訊號轉換到頻率域上，可能會發生洩漏效應(Leakage effect)，造成後續模態參數識別的誤差。本文利用非參數化方法中的Welch's method，來抑制洩漏現象發生，並提出改良多參考點最小二乘複頻域法的加權函數，以及用circular overlap的方式來改良Welch's method以提高識別結果的精度。

This study aims to identify the modal parameters for spectrum estimation using a nonparametric method. In frequency domain analysis, fast Fourier transform is employed to convert most time signals within measurement data into frequency domain. In this process, the leakage effect is readily observed, resulting in errors in subsequent modal parameter identification. In this thesis, the leakage effect was minimized using the non-parametric method-Welch’s method. Also, we propose a weighting function to improve the poly-reference least squares complex frequency domain method and a circular overlap method to improve the identification accuracy of the Welch’s method.

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