Funding for this research was provided by:
The work was partly supported by the National Natural Science Foundation of China (71571090)
Natural Science Foundation of Shaanxi Province (2017JM7022)
the Youth Innovation Team of Shaanxi Universities, the Project of Fundamental Research Funds for the Central Universities (JB190602)
the Interdisciplinary Foundation of Humanities and Information of Xidian University (RW180167)
Article History
Received: 3 January 2020
Revised: 2 May 2020
Accepted: 6 June 2020
First Online: 17 June 2020