1. Federal Institute of Education, Science and Technology Sul-Rio-Grandense, Passo Fundo 99.064-440, RS, Brazil
2. Department of Computer Science and Automation, University of Salamanca, 37008 Salamanca, Spain
3. Lisbon School of Engineering (ISEL), Polytechnic University of Lisbon (IPL), 1549-020 Lisbon, Portugal
4. Center of Technology and Systems (UNINOVA-CTS) and Associated Lab of Intelligent Systems (LASI), 2829-516 Caparica, Portugal