Liu, Feng
Funding for this research was provided by:
NNSF of China (11701333)
Support Program for Outstanding Young Scientific and Technological Top-notch Talents of College of Mathematics and Systems Science (Sxy2016K01)
Article History
Received: 27 April 2018
Accepted: 19 August 2018
First Online: 4 September 2018
Competing interests
: The author declares that they have no competing interests.