Fig. 10

Fault detection results. (a)–(f): The outlier detection result of the LOF-based fault detection method, i.e., \(LO{F_1}\left( {{{\varvec{e}}_k}\left( 1 \right)} \right)\)-\(LO{F_6}\left( {{{\varvec{e}}_k}\left( 6 \right)} \right)\). (g)–(l) The outlier detection results of the residual chi-square detection method, respectively based on \({{\varvec{e}}_k}\left( 1 \right)\)-\({{\varvec{e}}_k}\left( 6 \right)\).