1. CCTEG Chinese Institute of Coal Science, Beijing 100013, China
2. College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
3. Schobert International, LLC, Jordan, Minnesota 55352, United States
4. The EMS Energy Institute, the Pennsylvania State University, University Park, Pennsylvania 16802, United States
5. Kentucky Geological Survey, University of Kentucky, 228 Mining & Minerals Resources Building, Lexington, Kentucky 40506, United States
6. The Department of Earth Science and Engineering, Shanxi Institute of Technology, Yangquan 045000, Shanxi, China