Funding for this research was provided by:
National Natural Science Foundation of China (51439008)
National Natural Science Foundation of China (41572307)
Science and Technology Project of Transportation Department of Guizhou Province (2015122046)
China Scholarship Council (201604910678)
Article History
Received: 8 January 2018
Accepted: 6 August 2018
First Online: 20 August 2018