D.E. Tsygankov – Post-graduate Student, Department «Applied Mathematics and Informatics», 

Ulyanovsk State Technical University

E-mail: d.tsyg@mail.ru

A.F. Pokhilko – Ph. D. (Eng.), Associate Professor, Professor, Department «Applied Mathematics and Informatics»,

Ulyanovsk State Technical University

E-mail: afp@ulstu.ru