“…Commonly used feature extraction indicators include time domain-based ones such as kurtosis, root mean square (RMS), shape indicator (SI), etc [11,12]; frequency domain-based ones, such as frequency domain average (FDA), frequency center, etc [13,14]. Among them, kurtosis, RMS, and their variants are the most used statistical indicators [7,9,15]. Kurtosis is sensitive to early fault features [7,8,16] and can be used for early fault detection which is considered a prerequisite for PDA.…”