Funding for this research was provided by:
Fundamental Research Funds for the Central Universities (3102016ZY024)
Fundamental Natural Science Research Funds of Shaanxi Province (2016JM6077)
National Natural Science Foundation of China (61772424)
Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (CX201716)
National Natural Science Foundation of China (61602383)
Article History
Received: 14 July 2017
Revised: 17 July 2018
Accepted: 10 August 2018
First Online: 28 August 2018