L.A. Savchenkova - Student, Saint Petersburg State Polytechnical University. E-mail: La.savchenkova@yandex.ru
T.T. Kaverzneva - Ph.D. (Eng.), Associate Professor, Saint Petersburg State Polytechnical University. E-mail: kaverztt@mail.ru
D.A. Tarkhov - Dr.Sc. (Eng.), Professor, St.-Petersburg State Polytechnical University. E-mail: dtarkhov@gmail.com