在進行系統之模態參數識別的過程中，模態干涉常會造成可識別性的問題，影響系統識別結果的精度。產生模態干涉的主要原因通常有相近頻率、高阻尼比及阻尼非比例性過大等等。本文主要在探討時域之模態參數識別，針對前人所提出的亞伯拉罕時域法進行深入研究。
本文將延遲時間取樣擴充頻道法應用於亞伯拉罕時域法，針對系統響應在含有雜訊的影響下如何提高系統的識別精度進行探討。實際上系統的自由度為無窮多個，由於在進行模態參數識別時，選擇適當的系統階數可有效提升模態參數識別的準確性。吾人提出利用奇異值分解法引入最小二乘法求出系統矩陣，並同時判定出系統階數，從而提升亞伯拉罕時域法的有效性。另外，利用頻響函數圖判定系統階數時，頻響函數圖較易受到模態干涉程度的影響，導致模態遺漏的狀況，本文利用頻響函數中相位角的分布判定待識別的系統模態，從而提升模態識別的有效性。

Modal interferences often cause problems on identifiability and affect the accuracy of system identification during the process of modal parameter identification. Major causes of modal interferences include close frequencies, high damping ratios, non-proportional damping…etc. This thesis will investigate modal-parameter identification in time domain, by proposes a method of using the technique of channel-expansion in Ibrahim time domain method to improve identification accuracy.In general, selecting the order of system before using Ibrahim time domain method is important. This thesis proposes Singular Value Decomposition instead of the Method of Least Squares to solve the matrix of system and at the same time evaluate the order of system to avoid the phenomenon of omitted modes. In addition, this thesis proposes the use of the phase angle diagram of frequency response function in conjunction with the amplitude diagram. So that it is easier to distinguish the modes which are influenced by modal interference.

SUMMARY

Modal interferences often cause problems on identifiability and affect the accuracy of system identification during the process of modal parameter identification. Major causes of modal interferences include close frequencies, high damping ratios, non-proportional damping…etc. This thesis will investigate modal-parameter identification in time domain, by proposes a method of using the technique of channel-expansion in Ibrahim time domain method to improve identification accuracy.
In general, selecting the order of system before using Ibrahim time domain method is important. This thesis proposes Singular Value Decomposition instead of the Method of Least Squares to solve the matrix of system and at the same time evaluate the order of system to avoid the phenomenon of omitted modes. In addition, this thesis proposes the use of the phase angle diagram of frequency response function in conjunction with the amplitude diagram. So that it is easier to distinguish the modes which are influenced by modal interference.

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