1. College of Automation, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
2. School of Science, Wuhan University of Technology, Wuhan 430070, P. R. China
3. Department of Electronic Information and Mechanics, China University of Geosciences, Wuhan 430074, P. R. China
4. Petroleum Engineering College, Yangtze University, Jingzhou 420400, P. R. China