a Research Institute “Geodesy,” Krasnoarmeisk, Moscow oblast, 141292 Russia
b Faculty of Mechanics and Mathematics, Moscow State University, Moscow, 119992 Russia
c Moscow State University of Civil Engineering, Moscow, 129337 Russia
Correspondence to: *e-mail: elukashov@yandex.ru
Correspondence to: **e-mail: evrad07@gmail.com
Received 26 December, 2017
DOI: 10.1134/S1064562418030080