1. School of Resources and Safety Engineering, Chongqing University, Chongqing 400044, China
2. State Key Laboratory of the Gas Disaster Detecting, Preventing and Emergency Controlling, Chongqing 400037, China
3. China Coal Technology and Engineering Group, Chongqing Research Institute, Chongqing 400037, China
4. Huaibei Mining (Group) Co., Ltd., Anhui 235000, China