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 20 for “"the conjugate gradient method"”.
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The direct determination of nonlinear displacements of arbitrarily supported shallow shells using mathematical programming techniques
The nonlinear behavior of an asymmetrically loaded shallow shell of revolution with arbitrary edge conditions is investigated. The approach used in the present investigation is to obtain the displacement set which minimizes the finite-difference approximation of the shell potential energy by using …
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Construction of Centroidal Voronoi Tessellations Using A Conjugate Gradient Method Based On Trust Regions
… whose generating points coincide with the centroids (mass centers) of the corresponding Voronoi regions is called a centroidal Voronoi tessellation (CVT). Due to the natural optimization properties enjoyed by CVTs, they have diverse applications in many areas of science and engineering. …
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Polynomial Preconditioning for Conjugate Gradient Methods
The solution of a linear system of equations, Ax = b, arises in many scientific applications. If A is large and sparse, an iterative method is required. When A is hermitian positive definite (hpd), the conjugate gradient method of Hestenes and Stiefel is popular. When A is hermitian indefinite …
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A Parallel Aggregation Algorithm for Inter-Grid Transfer Operators in Algebraic Multigrid
… grow in size to address real-world problems, there is an increasing need for fast algorithms. Nowadays there are many GPU/CPU parallel approaches to solve such problems. Multigrid methods can be used to solve large-scale problems, or even better they can be used to precondition the conjugate …
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Investigating a Second-Order Optimization Strategy for Neural Networks
… this cumulative dissertation investigates the application of the conjugate gradient method CG for the optimization of artificial neural networks (NNs) and compares this method with common first-order optimization methods, especially the stochastic gradient descent (SGD). The presented …
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Adaptive finite element simulation of incompressible viscous flow
A finite element method is employed for solving two- and three-dimensional incompressible flows. The formulation is based on a segregated solution method. In this segregated formulation, the velocities and pressures are uncoupled and the equations for each are solved one after the other. This …
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Parallel Gauss-Newton method for CP decomposition
In this thesis, we formulate the Gauss-Newton algorithm to make it viable for running on distributed memory architectures and comparative to Alternating least squares algorithm for CP decomposition. Alternating least squares may exhibit slow or no convergence, especially when high accuracy is …
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The simulation of surface ship micro-bubble wakes
A method in which the transport and evolution of the bubble population in a surface ship wake is numerically simulated is presented. The simulation is accomplished by constructing an advective-diffusive transport model for the scalar bubble field and solving this model for late times after ship …
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Variational data assimilation for two interface problems
… system such that its evolution best fits the observed data. In this dissertation, we develop and analyze the variational data assimilation method with finite element discretization for two interface problems, including the Parabolic Interface equation and the Stokes-Darcy equation with the …
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Iterative Methods for the Reconstruction of Tomographic Images with Unconventional Source-detector Configurations
… a critical role in current medical practice for the evaluation of patients, particularly in the emergency department and intensive care units. Expensive high resolution stationary scanners are available in radiology departments of most hospitals. In many situations however, a small, inexpensive, …
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Reconstruction Methods for Optical Molecular Tomography
… on physiological and pathological activities at the cellular and molecular levels. Optical molecular tomography is an emerging area of molecular imaging. It locates and quantifies a 3D molecular probe distribution in vivo from data measured on the external surface of a small animal around the …
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Variable Viscosity Thermal Convection at Infinite Prandtl Number in a Thick Spherical Shell
Variable viscosity thermal convection at infinite Prandtl number in a thick spherical shell is modeled using the finite element method. The discretized tensor Navier-Stokes equations are solved with the multigrid method applied to the spherical elements. Numerically convergent solutions can be …
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Preconditioning of Karush--Kuhn--Tucker Systems arising in Optimal Control Problems
This work is concerned with the construction of preconditioners for indefinite linear systems. The systems under investigation arise in the numerical solution of quadratic programming problems, for example in the form of Karush--Kuhn--Tucker (KKT) optimality conditions or in interior--point …
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Optimal Control of Thermal Damage to Biological Materials
Hyperthermia is a cancer treatment modality that raises cancerous tissue to cytotoxic temperature levels for roughly 30 to 45 minutes. Hyperthermia treatment planning refers to the use of computational models to optimize the heating protocol to be used in a hyperthermia treatment. This thesis …
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Machine-Vision-Based Pose Estimation System Using Sensor Fusion for Autonomous Satellite Grappling
… during an on-orbit satellite servicing mission, the position and orientation (pose) of the satellite with respect to the servicing vessel is required in order to guide the robotic arm of the vessel towards the satellite. The main objective of this research is the development of a machine …
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Numerical simulation of microwave heating of a target with temperature dependent electrical properties in a single-mode cavity
This dissertation extends the work done by Hue and Kriegsmann in 1998 on microwave heating of a ceramic sample in a single-mode waveguide cavity. In that work, they devised a method combining asymptotic and numerical techniques to speed up the computation of electromagnetic fields inside a high-Q …
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Fast blind adaptive equalisation for multiuser CDMA systems
… in a CDMA system, we have to re-establish the orthogonally of codes which are used when combining input signals from many users onto a single communication path, as otherwise the performance of such system is limited significantly by inter-symbol interference (ISI) and multiuser access …
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Inertial iterative thresholding with applications to sparse and low-rank signal recovery
This thesis is concerned with a class of methods known collectively as iterative thresholding algorithms. These methods have been used by researchers for several decades to solve various optimization problems that arise in signal processing, inverse problems, pattern recognition and other related …
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Using the inverse heat conduction problem and thermography for the determination of local heat transfer coefficients and fin effectiveness for longitudinal fins
… energy consumption has increased tremendously in the last decades and this trend will continue, the concept of energy efficiency has become omnipresent. In electronics miniaturization has become a trend. Desktops, laptops, dvd-players, mp3-players, televisions,... are getting thinner and/or …