Table 2 Time domain features.
From: A remaining useful life prediction method based on PSR-former
\(Mean = \frac{1}{N}\sum\limits_{i = 1}^{N} {x_{i} }\) | \(Pk = max\{ \left| {x_{i} } \right|\}\) | \(RMS = \sqrt {\frac{1}{N}\sum\limits_{i = 1}^{N} {x_{i}^{2} } }\) |
|---|---|---|
\(RRMS(i) = \frac{RMS(i)}{{\frac{1}{N}\sum\limits_{i = 1}^{N} {RMS(i)} }}\) | \(Max = max\{ x_{i} \}\) | \(Std = \sqrt {\frac{1}{N}\sum\limits_{i = 1}^{N} {(x_{i} - \mu )^{2} } }\) |
\(Kurtosis = \frac{{E[(x - \mu )^{4} ]}}{{\sigma^{4} }}\) | \(Skewness = \frac{{E[(x - \mu )^{3} ]}}{{\sigma^{3} }}\) | \(Var = \frac{1}{N}(\sum\limits_{i = 1}^{N} {(\left| {x_{i} } \right| - \mu )^{2} } )\) |
