Trace Ratio Criterion-Based Kernel Discriminant Analysis for Fault Diagnosis of Rolling Element Bearings Using Binary Immune Genetic Algorithm

Table 3

Time-domain statistical features.

Feature	Eq.	Feature	Eq.
Standard deviation		Clearance factor
Peak		Shape factor
Skewness		Impact factor
Kurtosis		Square mean root
Crest factor

where is a digital signal series, , is the number of elements of the digital signal, and and are the mean value and root-mean-square value of the digital signal series, respectively.