Font Size: a A A

Based On Wavelet Multi-scale In Explosion Shock Wave Overpressure Signal Recovery Technology Research

Posted on:2014-02-25Degree:MasterType:Thesis
Country:ChinaCandidate:S LiuFull Text:PDF
GTID:2248330395482663Subject:Mechanical and electrical engineering
Abstract/Summary:PDF Full Text Request
This paper mainly studied on the multi-scale wavelet filtering methods which were conducted to recover the shock overpressure signal with strong noise due to internal explosion, the main research contents and conclusions include:1) This paper mainly studied the theory of wavelet transform combined with simulation, the result indicated that the multi-scale wavelet method for filtering has a big advantage compared with traditional filter means. Traditional filtering methods based on Fourier transform are less accurate to remove the high frequency information of the signal, while wavelet filtering can remove high frequency noise efficiently and retain the mutation information, it’s the most suitable means for recovery of shock overpressure signal due to internal explosion.2) Sym10wavelet was the suitable wavelet base of recovery overpressure signal due to internal explosion. It was the foundation of research on recovery of shock overpressure signal using multi-scale wavelet method with strong noise pollution. The time-frequency characteristics of three commonly used wavelet bases contained DbN, SymN and CoifN were analyzed in this paper. Considering the rapid mutations and multi-peaks of overpressure, sym10has the strongest capability to recover shock signal by comparing the different abilities of reconstructing the primary shock wave and the accuracy of extracting characteristic signal under strong-noise among DbN, SymN and CoifN wavelet bases. Thus sym10is the most suitable wavelet base of recovery pressure signal due to internal explosion.3) There are three main methods to recover the shock overpressure signal due to internal explosion based on the existing wavelet theory. It contains methods of wavelet transform modulus maxima, spatial correlation of wavelet transform coefficients and wavelet thresholding. The paper obtained that method based on wavelet transform modulus maxima was the most effective mean to recover the shock overpressure signal using de-noising simulation with Matlab software. Considering the reconstruction speed of wavelet coefficients from maxima modulus, the author has proposed improvement method combined with the wavelet threshold method. Simulation experiments showed that the improved wavelet modulus maxima could be more effective to recover the shock overpressure signal, and the reconstruction speed is improved.4) This paper provided quantitative evaluation of recovery effect about explosion shock wave overpressure signal. When correlation coefficient reaches47%and peak ratio is more than78%of the recovery signal and sampling of internal explosion shock wave signal, we can think the recovery signal approximation to the true inner explosion overpressure of shock wave signal, the recovery signal is the true signal.5) Wavelet signal recovery software was developped based on MATLAB programming language. For the convenient of using recovery technology and mastering the wavelet filtering theory to recover signal, the author compiled signal recovery software which contained translation de-noising and multi-scale wavelet. It was an independent installation package which played a significant role in promotion of the wavelet application in signal processing.
Keywords/Search Tags:Internal explosion, shock wave, overpressure signal, wavelet, multi-scale, recovery
PDF Full Text Request
Related items