Ilmir Masuilovich Bayanov,

Kazan National Research Technical Universitynamed after Tupolev,

10 K.Marx St., Kazan, 420111, Russia,

balan7@yandex.ru

Ilyas Kadirovich Gimaltdinov,

Bashkir State University,

32 Zaki Validi St., Ufa, 450076, Russia,

strbsu@mail.ru

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