“…In this study, considering the complementarity of different domain features, multidomain features are extracted from multisensor signals. To further reduce the redundant information contained in initial features, various dimension reduction techniques have been applied for feature selection and fusion, such as kernel principal component analysis (KPCA) [30], [34], [57], minimum redundancy maximum relevance (MRMR) [58], and locally linear embedding (LLE) [59]. Among them, KPCA can effectively fuse principal components from numerous features, and it is a popular technique for nonlinear dimensionality reduction in tool wear monitoring [30], [34], [57].…”