IEETA/DETI, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal. david.campos@ua.pt|IEETA/DETI, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal. david.campos@ua.pt|IEETA/DETI, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal. david.campos@ua.pt