1. School of Mathematical Sciences; Ocean University of China; Qingdao 266100 China
2. Institute for Sustainable Manufacturing and Department of Electrical and Computer Engineering; University of Kentucky; Lexington KY 40506 USA
3. Institute of Information and Systems Engineering; Henan University of Finance and Economics; Zhengzhou 450003 China
4. Department of Mathematics; Harbin Institute of Technology; Weihai 264209 China