V.A. Tsarev - Dr. Sc. (Eng.), Professor, Department ЭПУ, Yuri Gagarin State Technical University (Saratov). E-mail: tsarev_va@mail.ru I.O. Chigurov - Post-graduate Student, Department ЭПУ, Yuri Gagarin State Technical University (Saratov). E-mail: chigurov@gmail.com P.D. Shalaev - Ph. D. (Eng.), Head of Department, JSC «SPE «Almaz» (Saratov). E-mail: p.d.shalaev@yandex.ru