Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 83 for “"Fokker-Planck"”.
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Fokker-Planck models and globular cluster evolution
… cluster evolution using the orbit-averaged Fokker-Planck equation are compared with observations of the globular clusters M71 and NGC 6397. The first set of models studied includes a mass spectrum, a tidal boundary and allows for a central energy source from the formation, hardening and …
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Relaxation to equilibrium for kinetic Fokker-Planck equation
… behaviour of solutions $f_t$ of kinetic Fokker-Planck equation in $\mathbb{R}^d$, namely their convergence towards equilibrium $f_\infty$ in the form \[ \textrm{d}(f_t,f_\infty)\leq C_1 e^{-C_2 t}\textrm{d}(f_0,\mu) \] for appropriate distances $\textit{d}$ and constants $C_1 \geq 1$, …
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The Fokker-Planck and Related Equations in Theoretical Population Dynamics
… and of "white noise type", the SDE leads to a Fokker-Planck equation, a second order parabolic partial differential equation for the probability density function. Using separation of variables and simple transformations the Fokker-Planck equation reduces to a time independent ordinary …
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Solution of the Fokker-Planck Equation by Sequentially Optimized Meshfree Approximation
This thesis presents a technique to solve the Fokker-Planck equation by applica- tion of the Sequentially Optimized Meshfree Approximation (SOMA) method. It is well known that numerical solution of the Fokker-Planck equation is made di cult by the challenges of positivity enforcement, in nite …
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Fokker -Planck Modeling of Spherical Inertial Electrostatic, Virtual -Cathode Fusion Systems
… steady-state solutions of the bounce-averaged Fokker-Planck equation in which the Maxwellian ion population---absolutely confined in the electrostatic well---is dominant correspond to lowest ion recirculation powers (and hence highest fusion energy gains). Also, it is shown that the square-well …
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Efficient solution of the Fokker-Planck Equation via smooth particle hydrodynamics for nonlinear estimation
… systems is to solve the system's corresponding Fokker-Planck equation. The Fokker-Planck Equation (FPE) is the degenerate parabolic partial differential continuity equation that fully defines the evolution of the states' transition probability density function (PDF) over time. This also makes …
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A framework for ship stability in a seastate using the state-space Fokker-Planck method
… methods. Chief among them is the use of the Fokker-Planck equation (FPE), a deterministic partial differential equation governing the joint probability density function of the states of the SDE. The formulation for a rectangular barge rolling in beam waves is presented, with the approach …
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Drift-diffusion of a vacancy in inhomogeneous media and its material constants : a Fokker-Planck equation approach with an application to foreign exchange data
… the mobility and diffusion coefficients of a Fokker-Planck equation describing a vacancy hopping in inhomogeneous media in one dimension under a directed stress. The study used the general master equation as a basis for a physical model because of the mesoscopic view that the change in average …
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Analysis of moment-preserving methods for charged particle transport
… assessed. Among these methods are the well-known Fokker-Planck and Fermi approximations. These methods are known to be particularly bad for electrons. It is shown in this thesis that they are in fact very poor for all charged particle transport. Specifically, it will be seen that the Fokker-Planck …
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Nonuniqueness of Laws on State and Path Space: Flow Selections and Superposition for Fokker-Planck-Kolmogorov Equations and Convex Integration for Stochastic Hypodissipative Navier-Stokes Equations
… degree. In Parts I and II, we study parabolic Fokker--Planck--Kolmogorov equations (FPK equations), which are second-order differential equations for measures. In both parts, we prove structural results, which are of particular interest in cases of nonuniqueness of solutions.<br /><br /> More …
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The Cauchy problem for the Diffusive-Vlasov-Enskog equations
… diffusion. By choosing the diffusing term of Fokker-Planck type with or without dynamical friction forces. The Cauchy problem for the Diffusive-Vlasov-Poisson-Enskog equation (DVE) and the Cauchy problem for the Fokker-Planck-Vlasov-Poisson-Enskog equation (FPVE) are addressed.
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Poisson representation methods for stochastic models of chemical reactions
… master equations to be transformed into exact Fokker-Planck equations. The Fokker-Planck equations obtained using the Poisson representation are used to investigate some general features of chemical reaction systems whose steady state is thermodynamic equilibrium. The solutions for such systems …
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How well can one resolve the state space of a chaotic map?
… by computing the local eigenfunctions of the Fokker-Planck evolution operator in linearized neighborhoods of the periodic orbits of the corresponding deterministic system, and using overlaps of their widths as the criterion for an optimal partition. The Fokker-Planck evolution is then …
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Deterministic and Stochastic Approaches to Relaxation to Equilibrium for Particle Systems
… inhomogeneous kinetic theory (Boltzmann and Fokker-Planck equations) which motivates hypocoercivity. We also review the existing work on showing hypocoercivity using probabilistic techniques. We then present three different ways of showing hypocoercivity using stochastic tools. First we study …
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Discontinuous Galerkin Studies of Collisional Dynamics in Continuum-Kinetic Plasma
… While the continuum-kinetic Vlasov-Maxwell-Fokker-Planck system is well-established in theory and has been used as the basis for many approximate fluid equations, simulations utilizing the distribution function are relatively uncommon, due primarily to the high dimensionality of the problem. …
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Stochastic Averaging for Mechanical Systems
… distributions of the reduced system, the Fokker-Planck equation. Solving the steady-state two-dimensional Fokker-Planck equation forms a major part of this thesis; a finite-element method is used. Solving the Fokker-Planck equation necessitates the development of computational procedures …
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Modeling nonlinear stochastic ocean loads as diffusive stochastic differential equations to derive the dynamic responses of offshore wind turbines
… forms the input to a multi-dimension state-space Fokker-Planck equation, governing the dynamical response of the wind turbine structure. Its solution yields response, fatigue and failure statistics-information critical to the design of any offshore structure. The resulting Fokker-Planck equation …
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Markov-Analysen unebener Oberflächen
… stochastischer Systeme mithilfe einer Fokker-Planck-Gleichung für die Entwicklung bedingter Wahrscheinlichkeitsdichten (Pdf) in der Skalenvariablen. Die Methode und ihre Werkzeuge werden in dieser Arbeit auf einen Typ von Messdaten ausgedehnt, der bisher nur ansatzweise untersucht war. …
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Development and Application of Stochastic Methods for Radiation Belt Simulations
… diffusion, which solves the radiation belt Fokker-Planck equation using its equivalent stochastic differential equations, and presents applications of this method to investigating drift shell splitting effects on radiation belt electron phase space density. The theory of the stochastic …
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