Funding for this research was provided by:
Natural Science Foundation of Guangdong Province (2015A030310506)
Guangdong Planning Office of Philosophy and Social Science (GD16XGL38, 2016GZQN32)
National Natural Science Foundation of China (71731010, 71671048)
Article History
Received: 27 November 2017
Revised: 13 December 2017
Accepted: 21 December 2017
First Online: 16 January 2018