Funding for this research was provided by:
National Natural Science Foundation of China (51604267)
State Key Laboratory of Coal Resources and Safe Mining at CUMT (SKLCRSM15X05)
the Fundamental Research Funds for the Central Universities (2018QNA24)
Article History
Received: 5 September 2018
Accepted: 25 March 2019
First Online: 29 April 2019