School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China;
College of Computer Science, Beijing University of Technology, Beijing 100124, China;
School of Computer, National University of Defense Technology, Changsha 410073, China;
Haier Group, Qingdao 266000, China;
School of Computer and Information Technology, Beijing Jiaotong University, Beijing 100029, China;