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Localization of transient events in dispersive medium by attack time and filter bank analysis
Filip FRANEK(플필립),JunGu KANG(강준구),SungUk CHOI(최성욱),JongHo LEE(이종호) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
Localization of vibration events in structural systems is a challenge due to character of propagating waves in dispersive medium, in which bending waves propagate with a frequency dependent speed of sound. This property of solid materials is adverse for time of arrival methods used in non-dispersive medium. The proposed ideas tackle the problem of various propagation speed of each frequency component. The first method using attack time and magnitude information detects the change of envelope that is position dependent and becomes flatter and longer further from the origin of vibration. This envelope shape can be extracted by signal manipulation that obtains positive and smoothed magnitude envelope of the original signal or it can accumulate the signal from which the slope information can be obtained, and signals can be ranked. Second method utilize standard techniques for time estimation as triggering, and cross-correlation, but it separates the signals into multiple frequency bands beforehand as was suggested by White. The results give more detailed information about closeness of sound sources since there is not only a simple integer order to indicate the closeness of sensors from the vibration origin, whereas a histogram of each method is obtained by feeding the methods through the filter banks.