Department of Physics and Earth Sciences, University of Ferrara, Ferrara, Italy

Birmingham Centre for Railway Research and Education (BCRRE), School of Engineering, University of Birmingham, Birmingham B15 2TT, United Kingdom.

Department of Electrical and Photonics Engineering, Technical University of Denmark, Building 343, Office 026, DK-2800 Kongens Lyngby, Denmark

CENIMAT/I3N, Department of Materials Science, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, 2829-516, Portugal