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 15 of 15 for “"multi-grid"”.
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Improved lifetimes and synchronization behavior in multi-grid inertial electrostatic confinement fusion devices
… scaling analysis. The use of a single cathode grid causes short ion lifetimes and operation at high device pressure for simple ion generation both fundamentally limit the efficiency of these devices. Several improvements, including operation at much lower pressure with ion guns and the use of …
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The effect of energy input on the aggregation rate in an oscillating multi-grid reactor
Aggregation is a size enlargement mechanism which can be either desirable or inconvenient depending on the process involved. It involves the coming together or collision of two or more particles to form a larger single particle. It is a mechanism which is poorly understood and much research is …
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The efficient use of vectorized direct solvers in computational fluid dynamics
… equations is examined for both single-grid and multi-grid strategies. A procedure is developed for comparing the computational effort required for the direct method with that of the vertical line Gauss-Seidel iteration scheme in order to provide a criteria for choosing between the two …
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Scattering design : absorption enhancement and frequency selective metasurfaces
… limits on absorption enhancement due to multiple scattering from arrays of "metaparticles", applicable to general wave-scattering problems and motivated here by ocean-buoy energy extraction. We show that general limits, including the well known Yablonovitch result in solar cells, arise …
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Computational methods for the shape from shading problem
… scheme coupled with a special continuation-multi grid method for this formulation. We also allow for multiple image data and explicit knowledge of the location of discontinuities in surface height and orientation. Given multiple image data, we obtain excellent results even in the presence of …
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Improving programmability and performance for scientific applications
… solver using a novel coupling technique for multi-time scale methods for discrete finite element domains. We exploit domain semantics using a high-level dynamic runtime scheme to reorder and balance workloads to greatly improve runtime performance. The framework presented automatically …
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The effect of energy input on flotation kinetics in an oscillating grid flotation cell
… kinetics of quartz in a novel oscillating grid flotation cell. The effects of bubble size and particle size have been recognized as important variables affecting particle-bubble contacting in turbulent systems and are investigated in this thesis. The research work done in this thesis is a …
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Next Generation Algorithms for Magnetically Confined Fusion Reactor Simulations
… and material interfaces, preserving non-grid-aligned equilibria, ensuring high-order accuracy, capturing shocks, and maintaining the divergence-free condition of the magnetic field. Adaptive multi-grid solvers are used to compute steady-state plasma equilibria, while sharp-interface …
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Experimental Investigation of Wind Loading on a Ducted Wind Turbine
… tunnel. Turbulence was generated using a novel multi-grid approach that utilises two passive grids placed at a fixed distance from each other. Testing was done for four different turbulence intensities in the range of 1% to 16%. Fluctuating drag measurements were made using a multi axis load …
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Chebyshev spectral methods for potential field computation
… method is much faster than that of the spectral multi grid method. When there are discontinuities in the source function f and/or the conductivity o, the single-domain Chebyshev spectral method does not converge exponentially. In this case we use the multi-domain Chebyshev spectral method to …
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Transient Analysis of Isothermal Elastohydrodynamic Point Contacts
… constant squeeze film motion has been assumed. A multi-level/multigrid numerical method has been employed to obtain solutions for pressure distribution and film thickness for a wide range of loads, speeds, squeeze film velocity and different contacting materials. Rapid convergence has been …
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Numerical simulations of vortices near free and solid surfaces
… equation. A state of the art solver based on multigrid techniques was developed which gives excellent convergence rates. The result is a tool capable of modeling complex three-dimensional flows in a variety of configurations. Three different flow fields have been examined in order to determine …
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Structure-Preserving High Performance Computational Methods for Transport in Porous Media
… of state-of-the-art sci- entific libraries and multi-grid solvers like the FEniCS/Firedrake Projects, HYPRE, and Trilinos. It is shown that this spectrum can augment one’s ability to understand both the hardware and algorithmic efficiencies of popular numerical techniques like the finite element …
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Development and Application of Low-Order Computational Models of the Left Ventricle
… element model. However, as in many FEM studies, multiple combinations of the stiffness parameters lead to equally good fits to the data, implying uncertainty in parameter identification. We find that only a combined parameter representing the overall stiffness of the LV is identified robustly. In …