SMOOTHING THE TIME-FREQUENCY REPRESENTATIONS TO IMPROVE THE DIAGNOSIS FOR ENGINEERING STRUCTURES. - Minda, Andrea Amalia; Paun, Lucian; Burtea, Daniela Giorgiana; Gillich, Gilbert-Rainer (Annals of 'Constantin Brancusi' University of Targu-Jiu. Engineering Series / Analele Universităţii Constantin Brâncuşi din Târgu-Jiu. Seria Inginerie, 2021)