I.S. Zamulin - Ph.D. (Phys.-Math.), Senior Research Scientist, Khakas State University named after N.F. Katanova (Abakan) Е-mail: zamulin_ivan@mail.ru S.L. Gafner - Dr.Sc. (Phys.-Math.), Associate Professor, Khakas State University named after N.F. Katanova (Abakan) E-mail: sgafner@khsu.ru