1. College of Oceanography and Space Informatics, China University of Petroleum (East China), Qingdao, China
2. School of Computing and Information Technology, Great Bay University, Dongguan, China
3. Department of Mathematics, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA
4. Department of Information Systems, University of Maryland, Baltimore County (UMBC), Baltimore, MD, USA