1. College of Computer, Northwestern Polytechnical University, Xi'an, China
2. College of Computer and Information Technology, and the Hubei Key Laboratory of Intelligent Vision Based Monitoring for Hydroelectric Engineering, China Three Gorges University, Yichang, China
3. College of Control Science and Technology, Zhejiang University, Hangzhou, China
4. Department of Sciences and Informatics, Muroran Institute of Technology, Muroran, Japan