1. College of Computer and Information Science, Southwest University, Chongqing, China.
2. School of Software, Shandong University, Jinan, China.
3. Department of Computer Science, Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
4. Department of Computer Science, College of Electrical and Information Engineering, Beijing University of Civil Engineering and Architecture, Beijing, China.