1. College of Earth Sciences, Jilin University, Changchun, China
2. Jilin Institute of Geological Sciences, Changchun, China
3. School of Earth Sciences, Yunnan University, Kunming, China
4. Yunnan Key Laboratory of Statistical Modeling and Data Analysis, Department of Statistics, Yunnan University, Kunming, China
5. China Coal Geology Group Co., Ltd, Beijing, China