Funding for this research was provided by:
the project of 12th Five-Year planning of Education Science in Shanxi (GH15026)
the Fundamental Research Funds for the Central Universities (ZY1821)
Text and Data Mining valid from 2018-04-24
Received: 31 December 2017
Accepted: 17 April 2018
First Online: 24 April 2018
: The authors declare to have no competing interests.