## 3 Results and Discussion
\begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline
**CI** & **P10,P1** & **P2,P1** & **P3,P1** & **P4,P1** & **P5,P1** & **P6,P1** & **P7,P1** & **PS,P1** & **PS,P1** & **Selected** \\ \hline Mean & 0.0344 & 0.0079 & 0.0576 & 0.0756 & 0.0103 & 0.0551 & 0.0165 & 0.0969 & 0.0273 & ✓ \\ Kurtosis & 1.8664 & 0.1378 & 0.2153 & 0.0763 & 0.2812 & 0.0229 & 0.0822 & 0.0293 & 0.0544 & ✓ \\ Skewness & 0.4265 & 0.0680 & 0.0616 & 0.1370 & 0.1916 & 0.4084 & 0.0423 & 0.0161 & 0.1699 & ✓ \\ Energy operator & 0.5188 & 0.8403 & 0.0285 & 0.0011 & 0.0130 & 0.0513 & 0.5376 & 0.2571 & 0.2024 & ✓ \\ Zero crossing & 0.0545 & 0.0504 & 0.0914 & 0.2574 & 0.2043 & 0.1362 & 0.0741 & 0.0944 & 0.0109 & ✓ \\ Slope sign change & 0.0179 & 0.1600 & 0.2648 & 0.0399 & 0.2579 & 0.0339 & 0.3576 & 0.3789 & 0.7242 & ✓ \\ TMHO & 0.1061 & 0.0216 & 0.1777 & 0.2243 & 0.0270 & 0.1476 & 0.0393 & 0.2778 & 0.0729 & ✓ \\ Clearence factor & 0.3785 & 0.0045 & 0.0452 & 0.0121 & 0.1001 & 0.0329 & 0.2984 & 0.1857 & 0.1385 & � \\ Pulse & 0.4189 & 0.0105 & 0.0827 & 0.0051 & 0.0752 & 0.0239 & 0.2541 & 0.1810 & 0.1995 & � \\ Wilson amplitude & 0.0223 & 0.0961 & 0.0833 & 0.0059 & 0.1526 & 0.0015 & 0.3008 & 0.3050 & 0.2722 & � \\ Log detector & 0.0143 & 0.1348 & 0.0958 & 0.0278 & 0.1441 & 0.0088 & 0.2943 & 0.2784 & 0.2781 & � \\ Norm entropy & 0.0102 & 0.1506 & 0.1200 & 0.0335 & 0.1722 & 0.0168 & 0.2747 & 0.2784 & 0.2680 & � \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Bhattacharyya distance by CIs in printing failure. \begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline
**CI** & **P10,P1** & **P2,P1** & **P3,P1** & **P4,P1** & **P5,P1** & **P6,P1** & **P7,P1** & **PS,P1** & **PS,P1** & **Selected** \\ \hline Mean & 0.0016 & 0.0289 & 0.0618 & 0.0545 & 0.0442 & 0.0411 & 0.0333 & 0.0979 & 0.0664 & ✓ \\ Kurtosis & 0.6935 & 0.3533 & 0.2871 & 0.2039 & 0.5874 & 0.5694 & 0.0484 & 0.4872 & 0.8844 & ✓ \\ Skewness & 0.2828 & 0.0850 & 0.0304 & 0.0070 & 0.2501 & 0.0086 & 0.0559 & 0.0202 & 0.0445 & ✓ \\ Energy operator & 0.1577 & 0.9395 & 0.0116 & 0.0435 & 0.2758 & 0.0384 & 0.2111 & 0.0480 & 0.0400 & ✓ \\ Zero crossing & 0.2809 & 0.1266 & 0.0771 & 0.0356 & 0.0772 & 0.0958 & 0.3544 & 0.0552 & 0.0606 & ✓ \\ Slope sign change & 0.0997 & 0.0264 & 0.3210 & 0.0049 & 0.0124 & 0.0011 & 0.0426 & 0.0010 & 0.000 & ✓ \\ TMHO & 0.3601 & 0.3251 & 0.2599 & 0.2294 & 0.1819 & 0.1822 & 0.1395 & 0.2670 & 0.2683 & ✓ \\ Wave form & 0.0716 & 0.2126 & 0.1325 & 0.0012 & 0.0299 & 0.0405 & 0.0202 & 0.0260 & 0.0968 & � \\ Log entropy & 0.0931 & 0.2530 & 0.1784 & 0.0045 & 0.0060 &calculated. The results of the accuracy and AUC by accelerometer, failure and classifier are detailed in Table 9 and Table 10 respectively. In [PERSON] et al. [10], a 10 CIs ranking was performed using the filtering method for different gear DB in the time domain. When using the 10 CIs ranking in the RF and K-NN ranking models, the calculated accuracy in some DB was less than 85%. In the work done by [PERSON] et al. [38], 15 CIs were used to detect bearing failures, resulting in values higher than 95% accuracy for the RF classification model. In this research, by using the wrapper method for the ranking of CIs and the RF and K-NN classification models, the classification accuracy \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**A**} & \multicolumn{2}{c}{**Breaking**} & \multicolumn{2}{c}{**Cracking**} & \multicolumn{2}{c}{**Pitting**} & \multicolumn{2}{c}{**Scuffing**} \\ \cline{2-9}  & **RF** & **K-NN** & **RF** & **K-NN** & **RF** & **K-NN** & **RF** & **K-NN** \\ \hline A1 & 0.9922 & 0.9871 & 0.9965 & 0.9988 & 0.9885 & 0.9894 & 0.9905 & 0.9929 \\ A2 & 0.9920 & 0.9930 & 0.9970 & 0.9982 & 0.9969 & 0.9962 & 0.9943 & 0.9968 \\ A3 & 0.9956 & 0.9913 & 0.9950 & 0.9921 & 0.9935 & 0.9949 & 0.9952 & 0.9982 \\ A4 & 0.9959 & 0.9980 & 0.9950 & 0.9987 & 0.9981 & 0.9967 & 0.9971 & 0.9970 \\ A5 & 0.9964 & 0.9959 & 0.9983 & 0.9969 & 0.9926 & 0.9926 & 0.9961 & 0.9976 \\ A6 & 0.9994 & 0.9960 & 0.9937 & 0.9961 & 0.9973 & 0.9978 & 0.9992 & 0.9990 \\ \hline \hline \end{tabular}
\end{table}