Funding for this research was provided by:
National Center for Mathematics and Interdisciplinary Sciences, AMSS, CAS and NSFC Grant (11371349, 11688101)
National Natural Science Foundation of China (11671237)
Natural Science Foundation of Shandong Province (ZR2015AM001)
China Scholarship Council (201704910503)
Article History
Received: 10 December 2017
Revised: 4 May 2018
First Online: 22 May 2018