1. Information Technology College, Dalian Maritime University, Dalian, China
2. College of Artificial Intelligence, Dalian Maritime University, Dalian, China
3. Department of Computer and Information Sciences, Northumbria University, London, U.K.
4. Department of Computer Science, Faculty of Business and Physical Sciences, Aberystwyth University, Aberystwyth, U.K.
5. Department of Computer Science, Xiamen University, Xiamen, China