1. College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), D11, Xueyuan Road, Beijing 100083, P.R. China
2. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology (Beijing), D11, Xueyuan Road, Beijing 100083, P.R. China
3. The EMS Energy Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, United States