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Showing 1 to 20 of 174 for “"Diffusion Equation"”.
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Nonlinear methods for solving the diffusion equation.
Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering.
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Travelling Wave Analysis of a Nonlinear Diffusion Equation
… model, which can be formulated as a nonlinear diffusion free boundary (nonlinear Stefan) problem, indicate a travelling wave behaviour that is subsequently investigated using a travelling wave analysis. Considering first a simplified linear problem, we perform a travelling wave analysis that …
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Exponential Stability for a Diffusion Equation in Polymer Kinetic Theory
… we present an exponential stability result for a diffusion equation arising from dumbbell models for polymer flow. Using the methods of semigroup theory, we show that the semigroup U(t) associated with the diffusion equation is well defined and that all solutions converge exponentially to an …
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Lie group invariant finite-difference schemes for the neutron diffusion equation
… are used to solve a variety of differential equations. For the neutron diffusion equation, the typical local truncation error for standard finite difference approximation is on the order of the mesh spacing squared. To improve the accuracy of the finite difference approximation of the …
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Higher Order Nodal Methods for Solving the Steady-State Neutron Diffusion Equation
Made available in DSpace on 2017-07-06T18:55:59Z (GMT). No. of bitstreams: 3 Rajic_Hrabri_L_MS.pdf: 30908896 bytes, checksum: 49031fbb5ce3965a84550e8ed6a14c67 (MD5) Rajic_Hrabri_L_MS_ABS.pdf: 500847 bytes, checksum: dd84aaf9af22b9252ed2a0353a415f57 (MD5) license.txt: 4813 bytes, checksum: …
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The Diffusion Equation Method for Global Optimization and Its Application to Magnetotelluric Geoprospecting
… are ill-posed. We investigate the use of the Diffusion Equation Method (DEM) for global optimization in implementing an approximate quasisolution method for determining the size, shape, and orientation of an underground deposit. We examine the theoretical underpinnings of the DEM, first …
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Derivation of Similarith solutions for the One-Dimensional, One-Velocity Neutron Diffusion Equation Using Lie Group Transformation Theory
Made available in DSpace on 2017-07-06T18:55:28Z (GMT). No. of bitstreams: 3 Myers_William_L_MS.pdf: 26862151 bytes, checksum: fb1b194ae8d1df514a990af341ae3487 (MD5) Myers_William_L_MS_ABS.pdf: 596542 bytes, checksum: 6959b7aaf4a682d0c3b55423a0f04de3 (MD5) license.txt: 4813 bytes, checksum: …
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A theoretical and experimental investigation of moisture diffusion in wood
In this paper, the application of the diffusion equation to the problem of moisture movement below the fiber saturation point is investigated. The general diffusion equation was solved by numerical methods for the case of a concentration-dependent coefficient and a boundary condition of a specified …
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Asymptotic Problems Related to Smoluchowski-Kramers Approximation
… ``Physical" Brownian motion, of the Langevin's equation $\mu\ddot{q}_{t}^{\mu,\varepsilon}=-\dot{q}_{t}^{\mu,\varepsilon}+b(q_{t}^{\mu,\varepsilon})+ \sqrt{\varepsilon}\sigma(q_{t}^{\mu,\varepsilon})\dot{W}_{t},\ q_{0}^{\mu,\varepsilon}=q,\ \dot{q}_{0}^{\mu,\varepsilon}=p$, where $\dot{W}_t$\ is …
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A fast characteristic finite difference method for fractional advection-diffusion equations with non-linear reaction.
… can be modeled with fractional differential equations. This approach results in early arrival of contaminants and heavy-tail distributions observed in field experiments. The implicit finite difference scheme with the shifted Grunwald approximation discritizing the fractional …
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Numerical modelling of solute transport processes using higher order accurate finite difference schemes. Numerical treatment of flooding and drying in tidal flow simulations and higher order accurate finite difference modelling of the advection diffusion equation for solute transport predictions.
… of the processes of advection and dispersion-diffusion is the most crucial factor in solute transport simulations. It is generally appreciated that the first order upwind difference scheme gives rise to excessive numerical diffusion, whereas the conventional second order central difference …
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Massively parallel solver for the high-order Galerkin Least-Squares method
… high-order discretization of the Poisson equation, the advection-diffusion equation, and the Euler equation. The Robin-Robin interface condition is extended to the Euler equation using the entropy-symmetrized variables. The BDDC method maintains scalability for the high-order …
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Dynamics of Nonlinear Diffusion Processes
… purpose of this thesis is to analyze nonlinear diffusion processes. In particular, some of the results arrived at by Newman and Sagan in their 1981 paper "Galactic Civilizations: Population Dynamics and Interstellar Diffusion," will be reproduced by different means. First, a thorough analysis of …
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Application of Lie Groups to Discretizing Nuclear Engineering Problems
… one dimension for the time-independent neutron diffusion equation for Cartesian, cylindrical, and spherical geometries. This method will be expanded to constructing two-term recurrence relations for an arbitrary number of spatial regions, as well as detailing starting point values for type 2 and …
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Dynamics of biological macromolecules investigated by fluorescence depolarization
… rotational motion have been largely based on the diffusion equation. It has been implicitly stated that a ""jump"" model should give the same result for the anisotropy decay as the diffusion equation. In this work, we derive the general result from the jump model, where the excitation and emission …
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Dynamics of biological macromolecules investigated by fluorescence depolarization
… rotational motion have been largely based on the diffusion equation. It has been implicitly stated that a ""jump"" model should give the same result for the anisotropy decay as the diffusion equation. In this work, we derive the general result from the jump model, where the excitation and emission …
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Solution of the advection equation using finite difference schemes and the method of characteristics
… is achieved by the solution of the advection-diffusion equation. At present, there exist many numerical techniques which can be used to solve the advection-diffusion equation. The major difficulty when considering undertaking such a simulation, is what method should be used to calculate the …
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Experimental demonstration and exploration of quantum lattice gas algorithms
… implementation demonstrated here solves the diffusion equation, and it provides a test example from which to probe the strengths and limitations of this new computation paradigm. The NMR experiment consists of encoding a mass density onto an array of 16 two-qubit quantum information …
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Fast Solution Methods For Fractional Diffusion Equations and Their Applications
<p>Fractional diffusion equations model phenomena exhibiting anomalous diffusion that can not be modeled accurately by the second order diffusion equations. Because of the non-local property of fractional differential operators, the numerical methods have full coefficient matrices which require …
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