Table 1.

Alternative Feature Indicators and Their Parameter Definitions.

Feature indicator	Parameter definition	Feature indicator	Parameter definition
Mean	$\overline{x}=\frac{1}{n}\sum _{i=1}^n{x}_i$	Root mean square	${\overline{x}}_x=\sqrt{\frac{1}{n}\sum _{i=1}^n{x}_i^2}$
Geometric mean	$x_g=\sqrt[n]{x_1·x_2\cdots x_n}$	Range	$r=x_{\max }-x_{\min }$
Harmonic mean	$H_n=\frac{n}{\sum _{i=1}^n\frac{1}{x_i}}$	Waveform index	$S_f=\frac{\sqrt{\frac{1}{n}\sum _{i=1}^n{x}_i^2}}{\left|\overline{x}\right|}$
Peak index	$C_f=\frac{x_{\max }}{\sqrt{\frac{1}{n}\sum _{i=1}^n{x}_i^2}}$	$E_{3,0}$	$E_{3,0}={\int }_0^{t_1}{\left|x_{3,0}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,0}^k\right|}^2$
Kurtosis index	$K_f=\frac{\frac{1}{n}{\sum _{i=1}^n(x_i-\overline{x})}^4}{{\left[\frac{1}{n}{\sum _{i=1}^n(x_i-\overline{x})}^2\right]}^2}$	$E_{3,1}$	$E_{3,0}={\int }_0^{t_1}{\left|x_{3,0}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,0}^k\right|}^2$
Margin index	$C{L}_f=\frac{x_{\max }}{{\left(\frac{1}{n}\sum _{i=1}^n\sqrt{|x_i-\overline{x}|}\right)}^2}$	$E_{3,2}$	$E_{3,2}={\int }_{t_1}^{t_2}{\left|x_{3,2}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,2}^k\right|}^2$
2-Order moment (variance)	$M_2^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^2$	$E_{3,3}$	$E_{3,3}={\int }_{t_2}^{t_3}{\left|x_{3,3}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,3}^k\right|}^2$
3-Order moment (skewness)	$M_3^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^3$	$E_{3,4}$	$E_{3,4}={\int }_{t_3}^{t_4}{\left|x_{3,4}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,4}^k\right|}^2$
4-Order moment	$M_4^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^4$	$E_{3,5}$	$E_{3,5}={\int }_{t_4}^{t_5}{\left|x_{3,5}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,5}^k\right|}^2$
5-Order moment	$M_5^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^5$	$E_{3,6}$	$E_{3,6}={\int }_{t_5}^{t_6}{\left|x_{3,6}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,6}^k\right|}^2$
6-Order moment	$M_6^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^6$	$E_{3,7}$	$E_{3,7}={\int }_{t_6}^{t_7}{\left|x_{3,7}^k\left(t\right)\right|}^2\mathrm{dt}=\sum _{k=1}^m{\left|x_{3,7}^k\right|}^2$
7-Order moment	$M_7^{\prime }=\frac{1}{n}\sum _{i=1}^n{(x_i-\overline{x})}^7$