Table 1.

Time-domain features with their mathematical expression.

Features	Mathematical Expression
Mean	$m\left(t\right)=\frac{1}{N}{{\displaystyle \sum }}_{n}x\left[n\right]$
Variance	${\sigma }^2\left(t\right)=\frac{1}{N}{{\displaystyle \sum }}_n{(x\left[n\right]-m\left(t\right))}^2$
Skewness	$\gamma \left(t\right)=\frac{1}{N{\sigma }^3\left(t\right)}{{\displaystyle \sum }}_n{(x\left[n\right]-m\left(t\right))}^3$
Kurtosis	$k\left(t\right)=\frac{1}{N{\sigma }^4\left(t\right)}{{\displaystyle \sum }}_n{(x\left[n\right]-m\left(t\right))}^4$
Coefficient of Variation	$C\left(t\right)=\frac{\sigma \left(t\right)}{m\left(t\right)}$