Two-dimensional convective diffusion of a radioactive impurity with allowance for sorption in a porous medium

A mathematical model of the two-dimensional convective diffusion of radionuclide transfer in a porous medium has been considered. A fundamental solution in the form of Green's function has been obtained for this model. The analytical expressions of the impurity-concentration distribution for stationary conditions and for a few kinds of boundary conditions have been given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 417–420, May–June, 2008.     

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.     

Calculation of high-temperature sublimation refining in relation to the degree of sublimation for a material consisting of separate parts

This paper considers high-temperature sublimation of a two-component material consisting of parts differing in size. A sublimation equation is used to calculate the average impurity concentration in the condensate as a function of the degree of sublimation. The results demonstrate that the sublimation refining of a multipart material can be both more effective and less effective than the sublimation of a material in the form of a single block, depending on process and material parameters, but the difference between the purity levels achieved is not very large.     

Generalized diffusion equation for impurity atoms in semiconductor crystals

A diffusion equation is obtained for impurity atoms migrating by means of the formation of equilibrium complexes with intrinsic point defects, the distribution of which is nonequilibrium and nonuniform.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 5, pp. 805–810, November, 1989.     

Longitudinal diffusion of an impurity in a pipe with permeable walls

The problem of the spread of an impurity in a stream with fluid injection through the pipe walls is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 2, pp. 314–317, February, 1980.     

Real-time observation of impurity diffusion in silicon nanowires

Solid-state diffusion of the transition metal impurities, gold (Au), nickel (Ni), and copper (Cu), in silicon (Si) nanowires was studied by in situ transmission electron microscopy. Compared to diffusion in a bulk crystal, Au diffusion is extremely slow when the amount of metal is limited but significantly enhanced when an unlimited supply is available. Cu and Ni diffusion leads to rapid silicide formation but slows considerably with physical encapsulation by a volume-restricting carbon shell.     

Calculation of SHF and EHF microwave waveguides using relativistic approach with allowance for a finite conductivity

Calculation of a waveguide structure for the SHF and EHF microwave range using a relativistic approach is described. The influence of the finite conductivity of the surface of screened waveguide structures on their electric properties is considered. The results obtained using the proposed approach are compared to those provided by perturbative method.     

Calculation of diffusion coefficients for dense gases

Calculated values of mutual gas diffusion coefficients are compared to values measured by the laser interferometry method.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 3, pp. 438–442, March, 1988.     

Effective diffusion of impurity in laminar flow of liquid

The effective diffusion of an impurity in a flow of non-Newtonian liquid is investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 2, pp. 342–345, February, 1977.     

Calculation of dendritic liquation (microsegregation) in a solidifying steel ingot with allowance for ionic migration

Based on the mathematical model, the analytical solution of the problem of formation of dendritic liquation for different configurations of a dendritic cell has been obtained; the use of this solution makes it possible to optimize melting processes from the viewpoint of the chemical inhomogeneity of ingots and billets. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 98–105, January–February, 2009.     

Steady-state two-dimensional diffusion of a radioactive impurity in a channel with sorbing walls

We consider the analytical solution of the problem of steady-state diffusion of a radioactive impurity in a gas-filled channel of finite length with sorbing walls, with allowance for surface diffusion. The conditions under which the two-dimensional problem becomes one-dimensional are found.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 6, pp. 953–956, December, 1988.     

Calculation of the density of vaporization centers at the heating surface with an allowance for their mutual interaction

An expression is proposed for calculating the density of vaporization centers at the heating surface that accounts for the superheating, the roughness and material of the surface, the pressure, and the interaction between centers based on the Kenning model.Transted from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 4, pp. 638–641, April, 1990.     

Calculation of prolonged high-temperature sublimation refining of a material consisting of spherical parts

We demonstrate the possibility of calculating the time-dependent vapor composition and impurity distribution in a condensate for a prolonged high-temperature sublimation of a model material consisting of spherical parts differing in size (and identical in initial composition). The calculation procedure is based on the use of distillation equations for a binary substance in a nonequilibrium vaporization process. It has been shown that the condensate obtained through the sublimation of such a material has an increased impurity concentration compared to the condensate obtained through the sublimation of a single sphere.     

Calculation of evaporation of a twisted flow of cryogenic fluid in leidenfrost film boiling with allowance for the initial section

A mathematical model of evaporation of a twisted flow if a cryogenic fluid developed by the authors is supplemented by the calculation of an initial section. Calculational and experimental results are compared. Kazan State Technical University. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 741–747, September–October, 1996.     

Two-dimensional radiative heat transfer with allowance for shading

Radiative heat transfer with account taken for shading in an infinite cylinder whose contour is made up of arbitrary straight-line segments and which has variable temperature and emissivity on its two sides is examined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 1, pp. 49–57, January, 1976.     

Calculation of the effectiveness of plate cooling with coolant ejection at an angle to the main flow with allowance for the stagnant zone

A method is presented for calculating the efficiency of cooling of a flat surface with large ejection angles. The gaseous wall screen is calculated from formulas for tangential ejection.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 48, No. 5, pp. 715–719, May, 1985.