N.P. Petrov1, S.N. Petrova2, N. V. Korzhavina3, E. V. Lisovsky4

1 Ural State University of Economics (Ekaterinburg, Russia)
2 Technical University of the Ural Mining and Metallurgical Company
(Verkhnyaya Pyshma, Russia), 
2 Ural State Low University (Ekaterinburg, Russia)
3  Technical University of the Ural Mining and Metallurgical Company (Verkhnyaya Pyshma, Russia)
4 Kaluga branch of the Bauman Moscow State Technical University (Kaluga, Russia)