1. Professor, Faculty of Electrical Engineering, Univ. of Craiova, Craiova, RO-200440, Romania.
2. Lecturer, Faculty of Electrical Engineering, Univ. of Craiova, Craiova, RO-200440, Romania (corresponding author).
3. Assistant Professor, Faculty of Electrical Engineering, Univ. of Craiova, Craiova, RO-200440, Romania.