1. College of Information, Shanghai Ocean University, Shanghai 201306, P. R. China
2. State Key Laboratory of Simulation and Regulation of River Basin Water Cycle, China Institute of Water Resources and Hydropower Research, Beijing 100048, P. R. China
3. School of Computer Science and Information Technology, Northeast Normal University, Changchun 130117, P. R. China
4. Academic Affair Office, Pingdingshan University, Pingdingshan 467000, P. R. China