1. School of Computer Science, Northwestern Polytechnical University, Xi’an, China
2. College of Science, Guilin University of Technology, Guilin, China
3. School of Computer Science and Engineering, Guangxi Normal University, Guilin, China
4. National Engineering Laboratory for Integrated Aerospace-Ground-Ocean Big Data Application Technology, School of Computer Science, Northwestern Polytechnical University, Xi’an, China
5. Department of Computer Science, Aberystwyth University, Aberystwyth, U.K