1. Department of Mechanical Engineering, The University of Hong Kong, Hong Kong
2. School of Mathematics and the Frontiers Science Center for Mobile Information Communication and Security, Southeast University, Nanjing, China
3. Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
4. School of Mathematics, Southeast University, Nanjing, China
5. Graduate School of Informatics, Kyoto University, Kyoto, Japan
6. Systems Research Institute of the Polish Academy of Sciences, Warsaw, Poland