1. Department of Applied Mathematics, National Technical University ‘KhPI’, 2 Kyrpychova Str., 61002 Kharkiv, Ukraine
2. Faculty of Built Environment, Tampere University, P.O. Box 600, 33101 Tampere, Finland
3. Department of Higher Mathematics, National Technical University ‘KhPI’, 2 Kyrpychova Str., 61002 Kharkiv, Ukraine