Affiliation: | 1. Department of Mathematics, Lahijan Branch, Islamic Azad University, Lahijan, Iran;2. UISPA-LAETA/INEGI, Faculty of Engineering, University of Porto, Porto, Portugal;3. parsa@liau.ac.ir;5. UISPA-LAETA/INEGI, Faculty of Engineering, University of Porto, Porto, Portugal;6. Department of Electrical Engineering, Institute of Engineering, Porto, Portugal |