Classifying Power Quality Issues in Railway Electrification Systems Using a Nonsubsampled Contourlet Transform Approach. - Sinha, Pampa; Paul, Kaushik; Elzein, I. M.; Mahmoud, Mohamed Metwally; El‐Rifaie, Ali M.; Mbasso, Wulfran Fendzi; Ewais, Ahmed M. (Engineering Reports, 2025)