1. School of Electrical EngineeringXi'an Jiaotong UniversityShaanxi710049People's Republic of China
2. Robert W. Galvin Centre for Electricity InnovationIllinois Institute of Technology10 West 35th StreetChicagoUSA
3. Department of Electronic and Electrical EngineeringUniversity of BathBA2 7AYBathUK