1. School of Computer Engineering, Jimei University, Xiamen, China
2. Joint NTU-UBC Research Centre of Excellence in Active Living for the Elderly (LILY), Nanyang Technological University, Singapore, Singapore
3. School of Informatics, Xiamen University, Xiamen, China
4. School of Cyber Science and Engineering, Wuhan University, Wuhan, China
5. School of Computer Science and Technology, University of Science and Technology of China, Hefei, China
6. School of Computer Science and Engineering, Nanyang Technological University, Singapore, Singapore