Concentrations of heavy metals in soil and leaves of plant species Paulownia elongata S.Y.Hu and Paulownia fortunei Hemsl

This paper sums up the results of the research on heavy metals contents (Pb, Ni, Fe, Zn and Mn) in soil and leaves of the plant species, Paulownia elongata S.Y. Hu and Paulownia fortunei Hemsl. at the plantation established on the eutric brown soil in Banat (Vojvodina). The plantation, which served asthe control field is at the municipality of Bela Crkva, far away from the main traffic lines. Concentrations of analyzed heavy metals in the leaves of the tree species, Paulownia growing in urban and suburban conditions were compared with the concentration of polluters in the leaves of the tree species, P. elongata and P. fortunei in the experimental field in Bela Crkva

Neutral Radius Value Determination by Numerical Simulation Method at Ring Upsetting Test

Ring upsetting represents a basic operation for bulk forming process and has particular significance since it is used for contact friction determination. At ring upsetting by flat dies, metal flow depends upon tribological conditions present at contact surface. Thereby, two variants of metal flow are possible: a) two-way flow from neutral radius that is present at lower friction coefficient values, followed by ring’s inner radius reduction and ring’s outer radius increase. In such circumstances, neutral radius is found between inner and outer radius. b) one-way flow that occurs at higher friction coefficient values, where neutral radius is lower than ring’s inner radius. This paper is presenting the results of determination of relation between neutral radius value and friction coefficient. Such relation is determined by numerical simulation, by using Simufact.Forming software. Experimental verification of neutral radius position is conducted by metallographic analysis, for two friction coefficient values. Friction coefficient values are determined by ring upsetting by using dies, where in one case of ring upsetting, contact surfaces were ion implanted with nitroge