“…In the past decades, a variety of methods have been developed in bearing fault diagnosis, such as vibration analysis [ 1 ], acoustic analysis [ 2 ], noise analysis [ 3 ], thermal imaging analysis [ 4 ] and so on, among which the vibration analysis has proven to be the most efficient [ 5 ]. Many vibration signal processing tools have been used in signal preprocessing such as Fourier spectral analysis [ 6 ], wavelet analysis [ 7 ], empirical mode decomposition [ 8 ], and multi-wavelet transformation [ 9 ]. These vibration analysis methods have achieved good performance from non-adaptive analysis to adaptive analysis and from qualitative analysis to quantitative analysis [ 10 ].…”