## 4 Results and Discussion
### Experiment Results from CWRU
\begin{table}
\begin{tabular}{l l l l l} \hline \hline \multicolumn{2}{c}{**Fault Type**} & & & \\ \hline
**IR** & **Ball** & **OR Centered** & **OR Orthogonal** & **OR Opposite** \\ \hline \multirow{7}{*}{Drive end} & & 118 = N2/N2/N2, & 197 FE = N2, & \\  & & 119 = N2/N2/N2, & 197 BA = P2, & \\  & & 120 DE = P1, 120 BA = N2, & 198 FE = N2, & \\  & 3001 = N2/-/-/, & 121 BA = P2, 187 FE = N2, & 198 BA = N1, & \\  & 3002 = N2/-/-/, & 224 DE = N1, 224 BA = P2, & 199 FE = N2, & \\  & 3003 = N2/-/-/, & 225 DE = P2, 25 FE = N2, & 200 = N2/N2/P2, & \\  & 3004 = N2/-/-/, & _118 = P2/N2/N1, & 197 FE = N1, & \\  & 3001 = P2/-/-, & _119 = P1/N2/N1, & 197 BA = Y2, & \\  & 3002 = P2/-/-, & _120 DE = P2, 120 BA = P2, & 198 FE = P2, & \\  & 3003 = P2/-/-, & 121 BA = N2, 187 FE = N1, & 198 BA = P2, & \\  & 3004 = P2/-/-, & 224 DE = P2, 224 BA = P2, & 199 FE = N1, & \\  & 3001 = P2/-/-, & 225 DE = P2, 225 FE = N1, & 200 = P1/N1/P2, & \\  & 3002 = P2/-/-, & **118 = P2/N2/N1,** & **197 FE = N2,** & \\  & **3003 = P2/-/-,** & **119 = P2/N2/N1,** & **197 FA = P1,** & \\  & **3004 = P2/-/-** & **120 DE = P1, 120 BA = P2,** & **198 FE = N2,** & \\  & **121 BA = N2, 187 FE = N1,** & **198 BA = P2,** & \\  & **224 DE = P1, 224 BA = N1,** & **199 FE = N2,** & \\  & & **225 DE = P1, 225 FE = N1** & **200 = P2/N1/P2** & \\ \hline \multirow{7}{*}{Drive end} & & & 122 = N2/N2, & \\  & & 123 = N2/N2, & \\  & & 124 = P2/N2, 125 = P2/N1, & \\  & & 192 = N1/N1, 228 DE = N2, & 202 FE = N2, & \\  & & 229 DE = N2, 122 = P1/N2, & 204 FE = N2, & \\  & bearing faults & 174 = N2/N2, & _123 = P2/N2,_ & \\  & & **124 = P2/N1, 125 = P2/N1,** & \\  & & **192 = P2/N1, 228 DE = N2,** & \\  & & **229 DE = N2** & \\ \hline \multirow{7}{*}{Fan end} & & & 302 = N2/N2/N2, \\  & & & 305 FE = N2, \\  & & 306 = N2/N2/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/P2/N2, \\ \hline \multirow{7}{*}{Fan end} & & & 307 = N2/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/P2/N2, \\ \hline \multirow{7}{*}{Fan end} & & & 307 = N2/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/N1/N2, \\  & & 307 = N1/N1/N2, \\ \cline{1-1}  & & 307 = N1/P2/N2, \\ \cline{1-1}  & & 307 = N1/P2/N2, \\ \cline{1-1}  & & 307 = N1/P2/N2, \\ \cline{1-1}  & & 307 = N1/P2/N2 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Categorization of nondiagnosable records in [32] using SSK (normal font), SE (italic), SSE (bold). Each sampled record has three simultaneous measurements DE/FE/BA. Diagnosable records per approach: 7 partially diagnosable (SSK), 1 diagnosable and 26 partially diagnosable (SE), 25 Partially diagnosable records (SSE). and outer-race (OR) faults were categorized as P1, as failure harmonics were not dominant, as shown in Figure 7e,f. SE was the only approach that presented a Y2 record in OR (see Figure 7c), where failure frequency was dominant. Meanwhile, the IR in Figure 7a and Ball in Figure 7b were P2/P1 due to the fault frequency not being dominant. SSE presented smoother PSD (see Figure 7h) in comparison with that of SE (see Figure 7b), but categorization remained the same. Record 197 BA was the only downgraded one from Y2 for SE (see Figure 7c) to P1 for SSE (see Figure 7i). This exception can be justified because either approach (SK or SE) did not benefit from the short-time version at constant-speed data. Along with the qualitative diagnosis above discussed in Table 6, we also quantified the impact of short-term feature extraction through the corresponding classifier performance, which was estimated using the CWRU dataset with five-class labeled records. Table 7 presents the accuracy estimates and the advantage of short-time feature strategy in either estimator (SK or SE). State-of-the-art approaches removed the engine influence as an additional procedure. In our case, engine influence was not removed, resulting in more heterogeneous classes. Furthermore, the proposed approach preserved the physical interpretation, allowing for visual inspection and automatic failure detection analysis.