TY JOUR TI INCREASE OF POWER EFFICIENCY OF WOOD MACHINES KW wood machines KW power efficiency KW slipping KW speed JO Voronezh Scientific-Technical Bulletin AU Khakhina, A.. AU Nikiforova, A.. AU Rudov, M.. PY 2015 IS 4 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov