R.I. Batalov - Ph.D. (Phys.-Math.), Senior Research Scientist, E.K. Zavoyskii Kazan Physical-Technical Institute of RAS E-mail: batalov@kfti.knc.ru R.M. Bayazitov - Dr.Sc. (Phys.-Math.), Leading Research Scientist, E.K. Zavoyskii Kazan Physical-Technical Institute of RAS, Kazan State Power Engineering University E-mail: batalov@kfti.knc.ru I.A. Faizrakhmanov - Dr.Sc. (Phys.-Math.), Chief Research Scientist, E.K. Zavoyskii Kazan Physical-Technical Institute of RAS E-mail: batalov@kfti.knc.ru G.D. Ivlev - Ph.D. (Phys.-Math.), Senior Research Scientist, Belarussian State University, Minsk, Belarus