TY JOUR TI MATHEMATICAL MODELING OF THE DYNAMIC INTERACTION OF FOREST MACHINES AND SKIDDER SYSTEMS WITH THE SOIL WHEN WORKING ON SLOPES KW forests on slopes KW logging operations KW skidding KW soils KW forests on permafrost JO Forestry Engineering Journal AU Kalyashov, V.A. AU Shapiro, V.Y. AU Grigor'ev, I.V. AU Kunitskaya, O.A. AU Grigoreva, O.I. PY 2022 IS 12 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov