Funding for this research was provided by:
National Natural Science Foundation of China (20707016)
Natural Science Basic Research Plan in Shaanxi Province of China (2017JM2003)
Seed Foundation of Innovation and Creation for Graduate Students in Northwestern Polytechnical University (Z2019204)
Article History
Received: 23 May 2018
Accepted: 5 December 2018
First Online: 12 December 2018