Funding for this research was provided by:
National Natural Science Foundation of China (71471102)
Natural Science Foundation of Guangdong Province (2015A030310506)
Philosophy and Social Science Planning Program of Guangdong Province (GD16XGL38)
Article History
Received: 29 January 2018
Revised: 9 March 2018
Accepted: 14 March 2018
First Online: 26 March 2018