Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article A Window Width Optimized S-Transform | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2008 Article ID 672941 13 pages doi 2008 672941 Research Article A Window Width Optimized S-Transform Ervin Sejdic 1 Igor Djurovic 2 and Jin Jiang1 1 Department of Electrical and Computer Engineering The University of Western Ontario London Ontario Canada N6A5B9 2 Electrical Engineering Department University of Montenegro 81000 Podgorica Montenegro Correspondence should be addressed to Jin Jiang jjiang@ Received 14 May 2007 Accepted 15 November 2007 Recommended by Sven Nordholm Energy concentration of the S-transform in the time-frequency domain has been addressed in this paper by optimizing the width of the window function used. A new scheme is developed and referred to as a window width optimized S-transform. Two optimization schemes have been proposed one for a constant window width the other for time-varying window width. The former is intended for signals with constant or slowly varying frequencies while the latter can deal with signals with fast changing frequency components. The proposed scheme has been evaluated using a set of test signals. The results have indicated that the new scheme can provide much improved energy concentration in the time-frequency domain in comparison with the standard S-transform. It is also shown using the test signals that the proposed scheme can lead to higher energy concentration in comparison with other standard linear techniques such as short-time Fourier transform and its adaptive forms. Finally the method has been demonstrated on engine knock signal analysis to show its effectiveness. Copyright 2008 Ervin Sejdic et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION In the analysis of the nonstationary signals one often needs to examine their .
