Funding for this research was provided by:
National Natural Science Foundation of China (51474139)
SDUST Research Fund (2014JQJH106)
Key Research and Development Program of Shandong Province (2016GSF120002)
Qingdao City Science and Technology Project (16-6-2-52-nsh)
China Postdoctoral Science Foundation Funded Special Project (2016T90642)
China Postdoctoral Science Foundation Funded Project (2015M570602)
Open Fund of the Key Laboratory of Coal Mine Gas and Fire Prevention and Control of Ministry of Education (2015KJZX02)
Qingdao Postdoctoral Applied Research Project (2015194)