L.E. Sheinkman - Dr. Sc. (Eng.), Professor, Tula State University. E-mail: eliard@yandex.ru D.V. Dergunov - Ph. D. (Eng.), Engineer, Tula State University. E-mail: dmitrov83@mail.ru A.E. Chetverikova - Post-graduate Student, Tula State University. E-mail: eliard@yandex.ru