[ 1 ]
[Chunrui Ai]College of Applied Sciences, Beijing University of Technology Beijing 100124, China%School of Mathematics and Statistics, Zhengzhou University Zhengzhou 450001, China
[ 2 ]
[Shilin Yang]College of Applied Sciences, Beijing University of Technology Beijing 100124, China%School of Mathematics and Statistics, Zhengzhou University Zhengzhou 450001, China
