Table 1.

Time domain features.

Feature	Equation	Feature	Equation
Mean $(\overline{x})$	$\overline{x}=\frac{1}{n}{\displaystyle \sum _{i=1}^n{x}_i}$	Kurtisus $(x_{kur})$	$x_{kur}=\frac{{\displaystyle {\sum }_{i=1}^n{(x_i-\overline{x})}^4}}{(n-1)x_{std}^4}$
Peak $(x_p)$	$x_p=\max (x_i)$	Crest factor (CF)	$\mathrm{CF}=\frac{x_p}{x_{rms}}$
Root mean square $(x_{rms})$	$x_{rms}=\sqrt{\frac{1}{n}{\displaystyle \sum _{i=1}^n{x_i}^2}}$	Shape factor (SF)	$\mathrm{SF}=\frac{x_{rms}}{\overline{x}}$
Standard deviation $(x_{std})$	$x_{std}=\sqrt{\frac{1}{n-1}{\displaystyle \sum _{i=1}^n{(x_i-\overline{x})}^2}}$	Impulse factor (IF)	$\mathrm{IF}=\frac{x_p}{\overline{x}}$
Skewness $(x_{ske})$	$x_{ske}=\frac{{\displaystyle {\sum }_{i=1}^n{(x_i-\overline{x})}^3}}{(n-1)x_{std}^3}$	Margin factor (CIF)	$\mathrm{CIF}=\frac{x_p}{{\left(\frac{1}{n}{\sum }_{i=1}^n\sqrt{x_i}\right)}^2}$