1. Institute of Electronics and Informatics Engineering of Aveiro (IEETA) and Department of Electronics, Telecommunications and Informatics (DETI), University of Aveiro, Aveiro, Portugal
2. Center for Computational and Stochastic Mathematics (CEMAT) and Department of Mathematics, IST, University of Lisbon, Lisbon, Portugal
3. Department of Mathematics and Statistics, Helmut Schmidt University, Hamburg, Germany