1. College of Information Science and Engineering, Hunan Normal University, Changsha, China
2. State Grid Hubei Electric Power Research Institute, Wuhan, Hubei, China
3. School of Computer Science and Engineering, Central South University, Changsha, China
4. Department of Electrical and Software Engineering, University of Calgary, Calgary, Canada
5. Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Canada