A.L. Priorov - Dr.Sc. (Eng.), Associate Professor, P.G. Demidov Yaroslavl State University. E-mail: andcat@yandex.ru I.S. Nenakhov - Post-graduate Student, P.G. Demidov Yaroslavl State University. E-mail: zergoodsound@gmail.com V.V. Khryashchev - Ph.D. (Eng.), Associate Professor, P.G. Demidov Yaroslavl State University. E-mail: vhr@yandex.ru