“…One of the most common manners is to refine and extract the fault features from vibration signals by combination of a few of advanced signal processing methods (e.g., wavelet package transform (WPT) [8,10], hilbert transform(HT) [10,11], empirical mode decomposition (EMD) [11] and higher order spectra (HOS) [12]), to recognize the fault frequency used to compare with the theoretical value with involvement of expert’s empirical judgement. With the advent of artificial intelligence, the process of rolling bearing fault diagnosis is more and more treated as a procedure of fault pattern recognition, and its effectiveness and reliability significantly depend on the selection of dominant characteristic vector of the fault features [13]. Recently, Some entropy based methods, e.g., approximate entropy (ApEn) [14,15], sample entropy (SampEn) [16], fuzzy entropy (FuzzyEn) [16,17], hierarchical entropy (HE) [13,18] and hierarchical fuzzy entropy (HFE) [13], have been proposed to to extract characteristic vector of the fault features from bearing vibration signals.…”