I. A. Fanyaev - Lecturer-Trainee, Gomel State University n.a. Francisk Skorina (Gomel, Belarus). E-mail: Fanyaev@gmail.com V. P. Kudin - Dr.Sc. (Eng.), Associate Professor, Professor, Gomel Engineering Institute (Gomel, Belarus). E-mail: vkudzin@mail.ru