1. Department of Agricultural and Forestry Engineering, University of Valladolid, Duques de Soria University Campus, 42004 Soria, Spain
2. Department of Electrical Engineering, University of Cuenca, Central Campus, Cuenca 010104, Ecuador
3. Department of Electrical Engineering, School of Industrial Engineering, University of Valladolid, 47011 Valladolid, Spain
4. Department of Physics, University of Valladolid, Duques de Soria University Campus, 42004 Soria, Spain