1. Department of Electrical, Electronic Engineering and Computer Science, University of Catania, Catania, Italy
2. Department of Astronautical, Electrical and Energy Engineering, Sapienza – University of Rome, Roma, Italy
3. Politecnico di Torino, Dipartimento Energia “G. Ferraris,”, Torino, Italy
4. Department of Electrical and Computer Engineering, Baylor University, Waco, TX, USA