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Showing 2 results for Hosseini Kordkheili
Seyed Ali Hosseini Kordkheili, Sajjad Hajirezaie, Seyed Hassan Momeni Massuleh,
Volume 15, Issue 12 (2-2016)
Abstract
A comparison between three different time domain MIMO modal identification techniques i.e. ERA, EITD and PRCE is performed. The comparison is executed for discontinuous (mass and spring) and continuous (beam) systems in two different cases; i. e. experimental and operational modal analysis techniques. For this purpose the modal parameters of the system are measured using both direct time history data of impulse response (EMA) as well as correlation function of random response of the structure (OMA). From the results it is noted that some parameters like sampling frequency and total recording time have effect on their accuracy. Sensitivities of the results due to these parameters are measured and reported for all three considered methods. For this purpose the effecting parameters are altered between a couple of values and the sensitivity of the results is studied for all methods in both EMA and OMA cases. Finally, a comparison between the results of different methods is done and the accuracy of the methods is studied. It is concluded that ERA is the most accurate and reliable method with the least sensitivity to effecting parameters in both EMA and OMA cases.
S.h. Momeni Massouleh, M. Vesaghati Javan, S.a. Hosseini Kordkheili,
Volume 19, Issue 7 (July 2019)
Abstract
Empirical mode decomposition (EMD) is one of the new methods for decomposing a signal into its constituent components. The existence of multiple error sources has led to activities to eliminate or mitigate their effects. In this research, one of the major problems of EMD for the separation of noise-polluted signals, namely, mode mixing problem has been studied. To solve this problem, bandwidth EMD has been used, which enhances the EMD method and processes speed and greatly prevents mode mixing problem. Also, among the available methods to extract the instantaneous properties, the proper pair of instantaneous properties identification and signal normalization method is presented by an example. To investigate the efficiency of the bandwidth EMD method, using the optimal method of extracting the instantaneous properties, the experimental data of a faulty bearing have been studied and the instantaneous properties of both EMD method and the bandwidth EMD method have been extracted. Using the coefficient of variation criterion, it is shown that the bandwidth EMD method has a higher resolution and better results than EMD method. Finally, using information of decomposed white noise by EMD, the noise isolation quality of the original data is examined, which indicates a better decomposition of the results of the bandwidth EMD method.