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 25 for “"Particle Methods"”.
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Nonlinear Filtering: Dimensional Reduction and Particle Methods
"Our result is applied to the electric power system whose daily operations must be guarded against failures due to natural disasters, rogue attacks and other unexpected conditions. One of the central challenges in current power system operations is to develop a better estimation scheme which is …
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Efficient particle methods for solving the Boltzmann equation
A new particle simulation method for solving the Boltzmann equation is presented and tested. This method holds a significant computational efficiency advantage for low-signal flows compared to traditional particle methods such as the Direct Simulation Monte Carlo (DSMC). More specifically, the …
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Inference in sensor networks : graphical models and particle methods
… In part, this is due to a number of efficient methods for solving inference problems defined on graphical models, but even more important is the fact that many of these methods (such as belief propagation) can be interpreted as a set of message passing operations, for which it is not difficult …
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Random-vortex-particle methods applied to broadband fan interaction noise
… interaction noise. In contrast with classical methods to generate synthetic turbulence, random-vortex-particle methods can be extended to cope with inhomogeneous non-stationary turbulence with little modification from the formulation for homogeneous turbulence. The stochastic method is applied …
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Searching for signs of hidden sectors at the LHC: long-lived particle methods and models
… tools that cover gaps in parameter space for new particles. Open questions ask the origins of neutrino masses, the mechanisms underlying flavour mass hierarchies, the matter-antimatter asymmetry and signs of dark matter. These questions are solved in theories of new long-lived particles (LLPs) in …
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Correlated electron transport across atomic and molecular tunnel junctions
… such systems are usually treated with a single particle approximation such as NEGF+DFT non-equilibrium Green’s function plus density functional theory. Typical single particle treatments are incomplete due to approximations made in the treatment of the electronic structure leading to …
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A WC-MPS Model for Viscous Free Surface Flows
… that cannot be obtained directly through other methods. In other words, numerical simulation provides the assistance to interpret the theoretical phenomena and offers an alternative way to insightfully study the theories or experiments. In hydrodynamics simulations, the tradition mesh-based …
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Nonlinear filtering of high dimensional, chaotic, multiple timescale correlated systems
… lower dimensional problem, and to develop novel methods for dealing with issues that plague particle filtering when applied to high dimensional, chaotic, multiple timescale correlated systems. The first half of the dissertation is theoretical and addresses the question of approximating the …
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Development of a Hybrid Particle Continuum Solver
… situations that exhibit large fluctuations in particle density such as: planetary reentry, ablation due to arcing, rocket exhaust plumes, etc. When simulating these events, a high level of physical accuracy can be achieved with kinetic methods otherwise known as particle methods. However, this …
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Dynamics of dense gas-star systems : Black holes and their precursors
… of clean-cut aspects without any noise that particle methods suffer from. We study the most important physical processes that are readily available in the evolution of a spherical cluster, like self-gravity, two-body relaxation etc, the interaction with a central black hole and the role of a …
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Bayesian Inference for Nonlinear Dynamical Systems : Applications and Software Implementation
… dynamical systems, focusing on the use of methods such as particle filtering and smoothing. There are three areas of contributions: software implementation, applications of nonlinear estimation and some theoretical extensions to existing algorithms. The common theme for all the work …
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Algorithms for particle remeshing applied to smoothed particle hydrodynamics
This thesis outlines adaptivity schemes for particle-based methods for the simulation of nearly incompressible fluid flows. As with the remeshing schemes used in mesh and grid-based methods, there is a need to use localized refinement in particle methods to reduce computational costs. Various forms …
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Efficient simulation of molecular gas transport for micro- and nanoscale applications
… gradients, etc.), which make the traditional particle methods like the direct simulation Monte Carlo (DSMC) computationally inefficient. By considering only the deviation from equilibrium, the low-variance particle method introduced herein, simulates molecular gas transport in near-equilibrium …
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Lagrangian methods for ballistic impact simulations/
This thesis explores various Lagrangian methods for simulating ballistic impact with the ultimate goal of finding a universal, robust and scalable computational framework to assist in the design of armor systems. An overview is provided of existing Lagrangian strategies including particle methods, …
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Improving the Material Point Method
… material point method (GIMP) and the convected particle domain interpolation method (CPDI). Both GIMP and CPDI try to improve MPM by altering the geometry of the evolved material-point domain. Such changes lead to improvement of the quadrature part of the MPM algorithm. In this work, we give a …
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An evaluation of noise reduction algorithms for particle-based fluid simulations in multi-scale applications
Particle-based fluid simulations can be utilised to study phenomena ranging from galaxyscale, using smoothed particle hydrodynamics, plasma physics with particle-in-cell methods, aerospace re-entry problems, using direct simulation Monte Carlo, down to chemical, biological and fluid properties at …
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Kernel-based Lagrangian method for imperfectly-mixed chemical reactions, A
Current Lagrangian (particle-tracking) algorithms used to simulate diffusion-reaction equations must employ a certain number of particles to properly emulate the system dynamics---particularly for imperfectly-mixed systems. The number of particles is tied to the statistics of the initial …
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Vortex Methods for Fluid Simulation in Computer Graphics
… adds to graphical applications. Vortex methods are receiving increasing attention from the computer graphics community for simple and direct modeling of complex flow phenomena such as turbulence. However, vortex methods have not been developed yet to the level of other techniques for …
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State space modelling of extreme values with particle filters
… gradually over time. Sequential Monte Carlo methods known as particle filters provide an approach to inference for such models whereby observations are added to the fit sequentially. Though originally developed for on-line inference, particle filters, along with related particle smoothers, …
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An investigtion into the ability of a kinetic particle-based solver for study of gas flows in micro-scale structures
… pre-cognizance or trials. Even stochastic particle approaches, such as the DSMC, usually adept at resolving such flows, proves to be prohibitively expensive owing to the small signal to-noise ratio necessitating a large number of samples to obtain appreciably accurate results. The present …
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