N.I. Skripkin - Head of Laboratory, JSC «Pluton» (Moscow) E-mail: n.skripkin@pluton.msk.ru S.L. Morugin - Dr. Sc. (Eng.), Associate Professor, Head of Department, Nizhny Novgorod State Technical University n.a. R.E. Alekseev E-mail: smorugin@yandex.ru

Chong-Zu Nguyen1, D.G. Kovtun2

1,2 Volgograd State Technical University (Volgograd, Russia)

2 kdmob74@gmail.com