1. School of Mathematical Sciences, Nankai University, Tianjin 300071, China
2. Division of Biomedical Engineering and Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A9
3. School of Information Science and Engineering, Central South University, Changsha, Hunan 410012, China
4. School of Computing and Mathematics, Ulster University, Belfast BT37 0QB, UK