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In this thesis, the second generation wavelet transform theory and its application in the diagnosis of mechanical failure , the second generation wavelet denoising matlab based on the second generation of wavelet signal processing system . First, the proposed paper topic and its significance to elaborate ; Secondly, the Fourier transform method of signal analysis , wavelet analysis and wavelet packet analysis theory is introduced ; Furthermore , the introduction of the second generation wavelet transform principle and to study the classification of the prediction operator coefficient and update the coefficients of the operator and the solution process solve the prediction operator coefficient and update operators coefficient with different vanishing moments . Biorthogonal wavelet lifting scheme based construction methods and procedures , drawn out with a second-order , fourth-order , sixth-order , eight bands vanishing moments of the scaling function and wavelet function graphics ; Finally, the second generation wavelet transform is applied mine ventilator fault diagnosis , diagnosis of a fan rubbing fault , the results show that the second generation wavelet transform algorithm is simple , fast operation , low memory , wavelet construction is simple . The second-generation wavelet threshold denoising principle, a function of the threshold and threshold selection rules , using simulated signals verify the algorithm , and the algorithm is applied to the fan vibration signal denoising and fault diagnosis . The study results show that this method can effectively improve the signal-to-noise ratio , and reduce the noise contained in the original signal to improve the accuracy of fault diagnosis . Second generation wavelet signal processing system based on matlab second generation wavelet decomposition and reconstruction, denoising, scaling function and wavelet function structure , spectrum analysis function .
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