1. School of Computer Science and Technology, Harbin Institute of Technology Shenzhen Graduate School, HIT Campus Shenzhen University Town, Xili, Shenzhen 518055, P. R. China
2. School of Natural Sciences and Humanities, Harbin Institute of Technology Shenzhen Graduate School, HIT Campus Shenzhen University Town, Xili, Shenzhen 518055, P. R. China
3. Department of Computer Science and Information Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
4. Department of Computer Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan