TY JOUR TI Analysis and Selection of Geometric Parameters of a Hopper to Study the Process of Unloading of Bulk Materials KW hopper KW bulk materials KW arch formation KW loading and unloading devices KW statistical analysis JO Proceedings of Petersburg Transport University AU Vorob'ev, A.A. AU Migrov, A.A. PY 2022 IS 19 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"