“…In this study, 1, 2, 3, and 4 were used to indicate the degree of possible coal-gas outburst risk levels in the mine, where 1, 2, 3, and 4 indicate that no coal-gas outburst will occur (0 m 3 /t), the risk of coal-gas outburst disasters is small (0-5 m 3 /t), coal-gas outburst disasters will generally occur (5-10 m 3 /t), and serious coal-gas outburst disasters will occur (10 m 3 /t or more), respectively. KPCA [36,37] is mainly used to address nonlinear complex problems. It essentially employs a nonlinear function with extremely high nonlinear-processing capability, through which the introduced function maps a large amount of complex information in the original space to linearly divisible high-dimensional data.…”