1. Department of Mathematics, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, China; School of Information and Electrical engineering, Ludong University, 264025 Yantai, China
2. School of Mathematics and Statistics, Jiangsu Normal University, 221116 Xuzhou, China
3. School of Mathematics, Hefei University of Technology, 230009 Hefei, China
4. School of Mechatronic Engineering and Automation, Shanghai University, 200444 Shanghai, China
5. Department of Mathematics, Nanjing University of Aeronautics and Astronautics, 211106 Nanjing, China