... different discriminant measures in various applications ( 16 19 20 ). The approach used in this work is based on relative entropy that is now defined. The algorithm first chooses a time-frequency decomposition method such as wavelet packet transform or local trigonometric transform...

... defects in rolling element bearings. This approach is capable of completely extracting the characteristic frequencies related to the defect from the resonant frequency band. Based on the Shannon entropy of wavelet-based envelope spectra, a criterion to select optimal scale to monitor the condition...