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Báo cáo hóa học: "Review Article Techniques to Obtain Good Resolution and Concentrated Time-Frequency Distributions: A Review"

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: Review Article Techniques to Obtain Good Resolution and Concentrated Time-Frequency Distributions: A Review | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2009 Article ID 673539 43 pages doi 10.1155 2009 673539 Review Article Techniques to Obtain Good Resolution and Concentrated Time-Frequency Distributions A Review Imran Shafi 1 2 Jamil Ahmad 1 2 Syed Ismail Shah 1 2 and F. M. Kashif1 2 3 1 Centre for Advanced Studies in Engineering CASE G-5 2 Islamabad Pakistan 2Iqra University H-9 Islamabad Pakistan 3 Laboratory for Electromagnetic and Electronic Systems LEES MIT Cambridge MA 02139 USA Correspondence should be addressed to Imran Shafi imran.shafi@gmail.com Received 12 July 2008 Revised 13 December 2008 Accepted 23 April 2009 Recommended by Ulrich Heute We present a review of the diversity of concepts and motivations for improving the concentration and resolution of timefrequency distributions TFDs along the individual components of the multi-component signals. The central idea has been to obtain a distribution that represents the signal s energy concentration simultaneously in time and frequency without blur and crosscomponents so that closely spaced components can be easily distinguished. The objective is the precise description of spectral content of a signal with respect to time so that first necessary mathematical and physical principles may be developed and second accurate understanding of a time-varying spectrum may become possible. The fundamentals in this area of research have been found developing steadily with significant advances in the recent past. Copyright 2009 Imran Shafi 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 and Historical Perspective The signals with time-dependant spectral content STSC are commonly found in nature or are self-generated for many reasons. The processing of such signals forms the basis of many .