L = 1 2∇ · a∇ + b · ∇ on D ⊆ R and whose spatially dependent branching term is of the form β x z − α x z2, x∈D where β satisfies a very general condition and α > 0. In the case that α and β are bounded from above, we show that the measurevalued process can also be obtained as a limit of approximating branching particle systems. We give criteria for extinction/survival, recurrence/transience of ...

A two-dimensional (2D) single particle model for the copolymerization of propylene-ethylene with heterogeneous Ziegler-Natta catalyst is developed. The model accounts for the effects of the initial shape of the catalyst and carck/ pore patterns on the copolymer composition, polymerization rate and the average molecular weight properties. The spherical and oblate ellipsoidal shapes of catalyst p...

kinetics of the chemical leaching of chalcocite from a low-grade copper ore in a ferric sulfate medium was investigated using the constrained least square optimization technique. the experiments were carried out for different particle sizes in both the reactor and column at constant eh, ph, and temperature. the leaching rate increased with increase in the temperature. about 50% of the cu recove...

in the present work, the extraction of zinc from a sphalerite concentrate using sodium nitrate as an oxidant in a sulfuric acid solution was investigated. the effective parameters such as the temperature, sulfuric acid and sodium nitrite concentrations, stirring speed, particle size, and solid/liquid (s/l) ratio were analyzed. the dissolution rate increased with increase in the sulfuric acid an...