S.D. Ionov - Post-graduate Student, Institute of Mathematics and Mechanics (IMM), Ural Branch of the Russian Academy of Sciences. E-mail: progsdi@gmail.com
S.V. Sharf - Institute of Mathematics and Mechanics (IMM), Ural Branch of the Russian Academy of Sciences. E-mail: scharf@imm.uran.ru
Yu.A. Basistov - Ph. D. (Phys.-Math.), Senior Research Scientist, Institute of Applied Mechanics RAS (Moscow). E-mail: yuabas@mail.ru
Yu.G. Yanovsky - Dr. Sc. (Eng.), Professor, Institute of Applied Mechanics RAS (Moscow). E-mail: iam@iam.ras.ru
