TY JOUR TI MATHEMATICAL MODELING IN THE STUDY OF ROUGHNESS AS APPLIED TO INTERNAL SURFACES KW roughness KW mathematical model KW inner surface KW tap KW design of experiments KW geometric parameters JO Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies AU Batmanov, E.. AU Bulgakov, V.. AU Guseinov, R.. PY 2019 IS 2019 PB Astrakhan State Technical University