Affiliation: | a Department of Engineering Sciences and Methods, University of Modena and Reggio Emilia, via G.R. Fogliani 1, 42100 Reggio Emilia, Italy b Department of Mathematical Sciences, Polytechnic University of Marche, via Brecce Bianche, 60131 Ancona, Italy c A. Razmadze Mathematical Institute of the Georgian Academy of Sciences, 1 M. Aleksidze St., 0193 Tbilisi, Georgia |