Reliability Analysis with Multiple Dependent Features from a Vibration-Based Accelerated Degradation Test

Table 1

Candidate degradation features.

Feature	Formula	Feature	Formula
Mean		Clearance factor
Variance		Frequency center
Crest factor		Frequency variance
Kurtosis factor		HHT marginal energy (HME)
			Waveform factor		HHT marginal energy spectrum entropy (HMESE)	,
,

Note: is the number of frequency components in Hilbert-Huang Transform (HHT).