Regimes of a population density described by a nonlinear reaction-diffusion model

Certain stationary and nonstationary solutions of a reaction-diffusion model are obtained. Results of a numerical simulation of problems involving boundary conditions of the first kind are presented. A classification of regimes of change in population density is determined. Engineering Physics Institute, Moscow, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 2, pp. 179–186, March–April, 1996.     

Radionucleid propagation in a porous medium with allowance made for sorption and diffusion

An analytic solution is found for the concentration of the first and the second radionucleids in a porous medium. The effect is shown of radioactive decay and of diffusion on the occurrence time of the maximal concentration at the outlet of the absorber layer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 6, pp. 1100–1104, December, 1976.     

The Shubnikov-de Haas effect and thermoelectric properties of Tl-doped Sb2Te3 and Bi2Se3

Semiconductors - The influence of doping with Tl on the Shubnikov-de Haas effect at T = 4.2 K in magnetic fields up to 38 T in p-Sb2−x Tl x Te3 (x = 0, 0.005, 0.015, and 0.05) and...     

Cavitation in Liquid Rotation

Russian Engineering Research - In liquid rotation during ultrasound treatment, pressure due to the centrifugal force increases the total force on the cavitational bubbles, thereby increasing the...     

Aquathermolysis of heavy oil in reservoir conditions with the use of oil-soluble catalysts: part II – changes in composition of aromatic hydrocarbons

Abstract

This paper discusses aquathermolysis process of heavy crude oil from Boca de Jaruco reservoir, which is developed by CSS method. The catalysts based on cobalt, nickel, iron and cupper are used to intensify the in-situ conversion processes. The active form of catalysts generates after steam injection. In second part of work the conversion of aromatic hydrocarbons depending on thermo-catalytic conditions and composition of catalysts are investigated. The thermo-catalytic treatment destructs resin and asphaltene molecules. The destruction products transform into aromatic fractions. The correlation between the C4-phenanthrene/naphtabenzothiophen ratio and the yields of aromatics and resins are revealed. The increase in high-molecular aromatic hydrocarbon, particularly tetramethyl-phenanthrene content is observed. However, the content of heteroatom compounds such as naphtabenzothiophen is constant. Based on IR-spectroscopy, the changes in composition of aromatic fraction are revealed. The lowest value of aromaticity index is detected for experiments with only hydrogen donor (without catalysts) and for experiments with Ni-, Cu-based catalysts.