Funding for this research was provided by:
Northwest University (41630639, 41702302)
China Geological Survey (91025019)
Special/Youth Foundation of Taiyuan University of Technology (201901D211001)
Scientific and Technologial Innovation Programs of Higher Education Institutions in Shanxi (2019L0278)
Article History
Received: 1 September 2019
Accepted: 29 April 2020
First Online: 11 May 2020
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.