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 58 for “"numerical accuracy"”.
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Towards Improvement of Numerical Accuracy for Unstructured Grid Flow Solver
<p>An effort to improve the numerical accuracy of a three dimensional unstructured grid finite volume scheme is pursued in the present work. Unstructured grid methods have been widely used in computational fluid dynamics for the convenience of modeling complex geometries in realistic applications. …
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Code Verification and Numerical Accuracy Assessment for Finite Volume CFD Codes
… the correctness of the code through order of accuracy testing. The verification testing is performed on different mesh types which include triangular and quadrilateral elements in 2D and tetrahedral, prismatic, and hexahedral elements in 3D. The requirements of systematic mesh refinement are …
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An investigation into a method of designing insertion loss ladder filters avoiding incompatibilities
… design method (Darlington, Cauer) leads to numerical accuracy problems. Accepted methods for dealing with inaccuracy either replace the independent variable (frequoncy) by the more suitable "z-variable" (Szentirmai, Bingham) or introduce rules for polynomial manipulation based on …
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Higher Radix Floating-Point Representations for FPGA-Based Arithmetic
… three decades ago because they provide maximal numerical accuracy per bit of floating-point data. However, the unique nature of FPGA-based computation makes numerical accuracy per unit of FPGA resources a more important measure of the usefulness of a given floating-point representation. From …
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Framework for a Unified Macroscale Model of Magnetostriction
… form of the analytic equations that ensures numerical accuracy will be provided. Furthermore, a comparison to experimental data performed for several magnetostrictive materials will show that the model accurately predicts the behavior of Terfenol-D while two different iron gallium alloys are …
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Evaluating FFT Implementations Developed for use on FPGA Hardware
… Here, performance measurements include numerical accuracy, logic resource utilisation and maximum clock rates at which the implementation can be operated. This research project investigates, tests and compares three different FFT cores, namely the CASPER wideband, ASTRON wideband, and …
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Accuracy improvement of the second-kind Fredholm integral equations in computational electromagnetics
… iterative convergence but rather poor solution accuracy compared with the first-kind Fredholm integral equations. The loss of the numerical accuracy is mainly due to the discretization error of the identity operators involved in second-kind IEs. In the past decade, although much effort has been …
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Scaling finite difference methods in large eddy simulation of jet engine noise to the petascale: numerical methods and their efficient and automated implementation
… to satisfy the stringent requirements of CAA on numerical accuracy, finite difference methods in LES-based jet engine noise prediction rely on the implicitly formulated compact spatial partial differentiation and spatial filtering schemes, a crucial component of which is an embedded solver for …
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Heat conduction in two and three dimensions : computer modelling of building physics applications
… modelling a problem, such as how to choose the numerical mesh, the proper boundary conditions, numerical accuracy, numerical stability, etc. The second aim of the thesis is to provide advice and guidelines how to deal with various problems that occur in building physics applications. To this …
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A Two-Level Galerkin Reduced Order Model for the Steady Navier-Stokes Equations
… this thesis we propose, analyze, and investigate numerically a novel two-level Galerkin reduced order model (2L-ROM) for the efficient and accurate numerical simulation of the steady Navier-Stokes equations. In the first step of the 2L-ROM, a relatively low-dimensional nonlinear system is solved. …
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Numerical Study of Synthetic-Jet Actuation Effect on Airfoil Trailing Edge Noise
<p>The current study conducts numerical simulations to assess the possibility of employing Synthetic Jet Actuators (SJAs) as active noise control devices for reduction of airfoil acoustic radiation. High-accuracy numerical efforts employ a sixth-order accurate Navier-Strokes solver implementing a …
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Hamiltonian Paths and Strands for Unified Grid Approach for Computing Aerodynamic Flows
… applicable on the typical structured grid. The numerical accuracy and convergence rate are investigated under various flow conditions. The numerical efficiency was improved with a line-implicit method compared to a point-implicit method on the unstructured grid. Both stencil- and gradient-based …
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Nonlinear ultrasonic guided waves for quantitative life prediction of structures with complex geometries
… the longitudinal wave is investigated in detail. Numerical accuracy is validated from comparison with a closed, for both linear and non-linear code. The reflection of the non-linear P-wave gives confirmation for the correct treatment of the boundary condition. Finally the capabilities of the …
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GPU acceleration of the frequency domain acceleration search for binary pulsars
… Fresnel integrals, which increases the speed and numerical accuracy of the calculations, in both single- and double-precision. Furthermore, we develop a new estimate which improves the numerical accuracy of filter coefficients for accelerations close to zero. The GPU-accelerated pipeline achieves …
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Spin-Aware Neural Network Interatomic Potential for Atomistic Simulation
… exceptional phenomenological richness to high numerical accuracy, but at high cost and limited scale. Empirical potentials are faster and scale better, but cannot compare to ab initio in numerical and physical accuracy. Machine learning (ML) interatomic potentials (IPs) of recent years offer a …
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Tip leakage flow, heat transfer and blade lifing in a jet engine turbine
… program, was also performed to investigate the numerical accuracy of heat transfer calculations for fully developed flow. A literature survey of gas turbine blade materials and factors influencing turbine tip blade life was performed. Approximate temperature ranges for the significant blade life …
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Analysis of hybrid electrothermomechanical microactuators with integrated electrothermal and electrostatic actuation
… mechanical analysis, respectively. To preserve numerical accuracy and reduce computational time, we also incorporate a boundary integral formulation to describe the electric potential in the medium surrounding the actuator. We show through the example of a hybrid double-beam actuator, that …
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Mathematical modelling of flow and combustion in internal combustion engines
… prime sources of uncertainty, in current numerical models, namely turbulence modelling, inaccuracies in the solution procedure specific to moving grids, and combustion modelling. Two and three-dimensional computations of the in-cylinder turbulent flow in a diesel engine are described …
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Perturbative Check of the Action and Energy Lattice Sum Rules
… order and shown to be satisfied with good numerical accuracy. The various contributions to the quark-antiquark potential are analyzed, and the restriction of the expectation value of the sum over all spatial plaquettes (the energy in the magnetic fields) to one fixed time slice is examined.
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A Selective Approach to Hexahedral Refinement of Unstructured Conformal Meshes
… mesh in a specified region, improving numerical accuracy. Previous research using solely sheet refinement theory made the implementation computationally expensive and unable to effectively handle multiply-connected transition elements and self-intersecting hexahedral sheets. The …
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