Funding for this research was provided by:
Natural Science Foundation of Shaanxi Provincial Department of Education (2019jjxxxx)
the Applied Characteristic Discipline in Xiangnan University
Text and Data Mining valid from 2019-03-21
Received: 9 April 2018
Accepted: 30 January 2019
First Online: 21 March 2019
: The authors declare that they have no competing interests.