1. Navigation College, Dalian Maritime University, Dalian 116026, China
2. Department of Computer Science, The University of Alabama, Tuscaloosa, AL 35487-0290, USA
3. School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
4. School of Mechanical, Electrical, Information Engineering, Shandong University, Weihai 264209, China