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Effective Diffusion Coefficient in Void Regions
Nuclear Science and Engineering, 1962The muitigroup diffusion theory for a virtually critical medium with homogeneous regions, when applied to a void region having one-dimensional cylindrical geometry, yields slightly erroneous results as a result of the fact that the theory ignores the neutron current traversing the gap.
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Effect of sampling on the estimation of the apparent coefficient of diffusion in MRI
2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2017The Apparent Diffusion Coefficient (ADC) is a quantitative measure derived from MRI that is able to asses the amount of diffusion within living tissues. It is employed to characterize different diseases and to evaluate response to therapy. For ADC estimation, the diffusion signal needs to be sampled using a small number of values, presenting ...
Santiago Aja-Fernández +2 more
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Time-dependent neutron diffusion coefficient for the effective diffusion equation
Progress in Nuclear Energy, 2019Abstract The time-dependency of neutron diffusion coefficient as well as neutronic interfacial coefficients in nuclear reactors at short time-scale is investigated via the volume averaging method. The boundary-value problems of governing differential equation for spatial deviations around averages of local variables are developed in this work.
Carlos G. Aguilar-Madera +2 more
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Effective Diffusion Coefficient in Porous Media
Journal of Applied Physics, 1963Recent calculations by Prager of upper bounds for the effective diffusion coefficient (or conductivity) in porous media, in terms of certain statistical parameters of the random geometry, are reformulated so as to apply specifically to a bed of spherical particles.
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Effect of geometry on the effective moisture transfer diffusion coefficient
Journal of Food Engineering, 1996Abstract The effective moisture transfer diffusion coefficient ( D eff ) of ready-to-eat breakfast cereals (RTE) is determined either from an individual particle or a bulk of material in the literature. The D eff is assumed to be the same in both cases which can be dependent on the material thickness. In this study, the effect of bed depth of
M.Ahmet Tütüncü, T.P. Labuza
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Spin waves and spin diffusion in Fermi liquids: Bounds on effective diffusion coefficients
Physical Review B, 1986We investigate the accuracy of the usual relaxation-time approximations, involving the spin-diffusion lifetime tau/sub D/, which are generally made in analyses of spin waves and the Leggett-Rice effect in Fermi liquids. By employing the variational methods of Ah-Sam, Hojgaard-Jensen, and Smith and of Egilsson and Pethick, we are able to determine upper
, Bedell, , Meltzer
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Determination of the effective diffusion coefficient
2011The equation for drying kinetics is obtained, base on the analytical solution of the differential equation with a boundary condition in the form of the flux. This equation was initially developed by G. Efremov. In this paper a modification of the Efremov drying equation will be presented.
Vasić, Miloš +3 more
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Calculations of the effective diffusion coefficient for inhomogeneous media
Journal of Physics and Chemistry of Solids, 2002Abstract We suggest a modification of the well-known Maxwell-Garnett equation for the mobility (effective diffusion coefficient) in two-phase media (a matrix with inclusions) which permits the description of a wide range of experimental situations.
Kalnin, J., Kotomin, E., Maier, J.
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Consistent measurement of diffusion coefficients for effectiveness factors
Chemical Engineering Science, 1980Abstract An examination has been made of how structural factors influence the measured values of effective diffusivity using the steady(Wicke-Kallenbach) and unsteady (chromatographic) state methods. For a solid with a typical bidisperse pore size distribution it is shown that the steady state method tends to give longer values.
C. McGreavy, M.A. Siddiqui
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Effective diffusion coefficient for two-band systems
Applied Physics Letters, 2005The effective longitudinal diffusion coefficient for two-band systems is determined. Emphasis is put on the nonlinear transport regime realized at high electric fields. Particular results are obtained for bipolar transport in two-band semiconductors and vertical transport in semiconductor superlattices.
P. Kleinert, V. V. Bryksin
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