1. College of Mathematics and Computer ScienceFuzhou University Fuzhou China
2. Fujian Key Laboratory of Network Computing and Intelligent Information Processing Fuzhou China
3. Key Laboratory of Spatial Data Mining & Information SharingMinistry of Education of China Fuzhou China
4. Department of Electrical Engineering and Computer ScienceUniversity of Stavanger Stavanger Norway
5. Department of Computer ScienceMongolian National University Ulan Bator Mongolia