1. School of Mining and Petroleum Engineering, University of Alberta, Edmonton, AB T6G 2R3, Canada
2. Faculty of Civil Engineering and Resource Management, AGH University of Krakow, 30-059 Krakow, Poland
3. GIG Central Mining Institute, 40-166 Katowice, Poland
4. State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China