1. Departamento de Informática y Automática; Universidad de Salamanca; Campus Plaza de la Merced s/n; 37008; Salamanca; Spain
2. Department of Artificial Intelligence and Applied Electronics; Technological Institute of Castilla and Leon; Poligono Industrial de Villalonquejar; C/Lopez Bravo 70; 09001; Burgos; Spain
3. Department of Civil Engineering; University of Burgos; EPS Politécnica, Campus Vena, Edificio C. C/Francisco de Vitoria; s/n; 09001; Burgos; Spain
4. Department of Computer Science; University of Oviedo; Campus de Viesques s/n; 33204; Gijón; Spain