a
Institute of Continuous Media Mechanics, Ural Branch of RAS, Perm, Russia
b
Perm National Research Polytechnical University, Perm, Russia
E-mail: raikher@icmm.ru
c
Institute of Continuous Media Mechanics, Ural Branch of RAS, Perm, Russia
E-mail: stepanov@icmm.ru
d
Perm State University, Perm, Russia
E-mail: anz@psu.ru