Funding for this research was provided by:
National Natural Science Foundation of China (21878200, U1610115, 21676174)
International S&T Cooperation Program of Shanxi province (201703D421038)
Shanxi Scholarship Council of China (2017-036)
Joint Fund of Shanxi Provincial Coal Seam Gas (2015012019)
Article History
Received: 25 July 2018
Accepted: 2 April 2019
First Online: 8 April 2019
Compliance with ethical standards
:
: The authors declare no conflict of interest.