A Morphological Filtering Method Based on Particle Swarm Optimization for Railway Vehicle Bearing Fault Diagnosis

Table 6

The kurtosis values of collected operations of the outer-race fault signal.

Operator	Kurtosis
Dilation	1.33
Morphological gradient (MG)	2.61
Open	1.13
Difference filter (DIF)	2.76
White top-hat transform (WTH)	3.38
Close-open (CO)	0.86
Combination morphological filter (CMF)	0.94
Combination morphological filter hat (CMFH)	2.33
Erosion	1.02
Close	1.07
Close and open average (AC&O)	0.98
Black top-hat transform (BTH)	6.39
Combination of WTH and positive BTH (CWTH&PBTH)	1.32
Open-close (OC)	0.98
CO and OC gradient (GCO&OC)	3.01
Morphology gradient product operation (MGPO)	4.56