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 29 for “"Matrix-free"”.
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A matrix-free linear programming duality theory
Thesis: M.S., Massachusetts Institute of Technology, Department of Mathematics, 1979
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Shape optimization using a matrix-free Newton method
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
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Matrix-free time-domain methods for general electromagnetic analysis
… problems. If a computational method can be made free of matrix solutions, then it has a potential of solving very large scale problems. Among existing computational electromagnetic methods, the explicit finite-difference time-domain (FDTD) method is free of matrix solutions. However, it requires …
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A matrix-free numerical bifurcation method applied to sheared annular electroconvection
… in sheared annular electroconvection using matrix-free numerical bifurcation methods. In particular, we study a model that simulates a liquid crystal film in the Smectic A phase suspended between two annular electrodes, and subjected to an electric potential difference and a shear applied by …
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Matrix Free approach for Raviart-Thomas anisotropic Tensor Product Finite Elements
… thereby extend the existing implementation of matrix free framework in deal.ii. The extensions allow the framework to also support anisotropic vector-valued finite elements in addition to existing isotropic Lagrangian finite elements. Tests on finite element operators in divergence conforming …
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Hessian Matrix-Free Lagrange-Newton-Krylov-Schur-Schwarz Methods for Elliptic Inverse Problems
… Newton-Krylov method employed in a Hessian-free manner. The preconditioners have an inner-outer structure, taking the form of a Schur complement (block factorization) at the outer level and Schwarz projections at the inner level. However, building an exact Schur complement is prohibitively …
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Efficient matrix-free implementation and automated verification of hybridizable discontinuous Galerkin finite element methods
… mapping procedure amenable to both quadrature-free and quadrature-based discretizations, and compare the accuracy of the two on different problem geometries. We verify the quadrature-free approach, demonstrating that optimal orders of convergence can be obtained, even on non-affine and …
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On matrix-free pseudo-arclength continuation methods applied to a nonlocal partial differential equation in 1+1D with pseudo-spectral time-stepping
… observed in Eftimie et al. [5]. Finally we apply matrix-free, pseudo-arclength continuation methods with consideration given to symmetries within the model in an attempt to trace curves from known states to more dynamically exotic regions of parameter space. The ow operator is used to condition …
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Methods for Analysis of Nonlinear Thermoacoustic Systems
… in large thermoacoustic sytems are presented: matrix-free continuation methods and gradient methods. Continuation methods find limit cycles numerically in the time domain, with no additional assumptions other than those used to form the governing equations. Once the limit cycles are found, …
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The preparation of porous microcolumn arrays of silicon, and post-ionization of neutral particles from DIOS-MS
Matrix-free desorption/ionization on porous silicon (DIOS) has been used in this work to detect low molecular weight compounds by mass spectrometry. Post-ionization of neutral particles is a promising alternative technique for improving parent ion yields, particularly if gaseous neutrals can be …
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Iterative Reconstruction Algorithms for Polyenergetic X-ray Computerized Tomography
… iterative. In this thesis, we discuss a new fast matrix-free iterative reconstruction method based on a polyenergetic model. While most modern x-ray CT scanners rely on the well-known filtered back-projection algorithm, the corresponding reconstructions can be corrupted by beam hardening …
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Optimization And Validation Of Direct Analysis In Real Time Mass Spectrometry (dart-Ms) For Quantitation Of Sugars To Advance Biofuel Production
… range was developed using sugar standards in matrix-free solvents with the use of internal standards. </p> <p><em>iii) Validation of the DART-MS method for quantitation of six-carbon sugars in saccharification matrix</em>: Validation of the DART-MS method was performed to determine the limits …
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Fast Solvers for Models of Fluid Flow with Spectral Elements
… to efficiently eliminate the interior degrees of freedom and subsidiary subdomain solves. We demonstrate the effectiveness of this preconditioner in numerical simulations using a spectral element discretization. This work extends the use of Fast Diagonalization to steady convection-diffusion …
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Exploring global dynamics in a low order model of parallel shear flow
… the parameter space surrounding the it. We use a matrix-free manifold computation method to find a homoclinic orbit of limit cycles. Finally we will discuss a method to continue the homoclinic orbit.
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A discontinuous Galerkin spectral element method compressible flow solver
… include exponential spatial convergence, fast matrix-free operator evaluation, implicit time-stepping schemes, highly-scalable iterative solvers, effective stabilization techniques, and moving-mesh capabilities. Novel nonlinear filter-based artificial viscosity methods have been developed for …
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Novel Liquid extraction method for detecting Native-wood Formaldehyde
… emission exists in a complex equilibrium in wood matrix. The reaction between formaldehyde and wood hydroxyl groups/water can hinder the complete formaldehyde extraction. In order to have a complete formaldehyde extraction, a stronger nucleophile than hydroxyl and water groups is needed. In this …
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Lightly-Implicit Methods for the Time Integration of Large Applications
… full order of convergence. These methods are matrix free, have low memory requirements, and are particularly well suited to parallel architectures. Linear stability analysis of K-methods is leveraged to construct implementation improvements for both Rosenbrock-Krylov and exponential-Krylov …
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A Computational Framework for Assessing and Optimizing the Performance of Observational Networks in 4D-Var Data Assimilation
… for quantifying the observation impact include matrix free linear algebra algorithms and low-rank approximations of the sensitivities to observations. The sensor network configuration problem is formulated as a meta-optimization problem. Best values for parameters such as sensor location are …
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Acceleration Techniques for Industrial Large Eddy Simulation with High-Order Methods on CPU-GPU Clusters
… integration methods are implemented on GPUs: the matrix-free GMRES solver and a novel local GMRES-SGS method. Parametric studies are done to evaluate their performance on LES benchmark cases. On the High-Lift Common Research Model case for the 2021 4th AIAA High-Lift Prediction Workshop, both GPU …
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Model and Data Reduction for Control, Identification and Compressed Sensing
… for practitioners, and is a first step towards a matrix free approach to solve AREs. Numerical examples for n >= 100,000 unknowns are presented. In Chapter 4, we develop a system identification method which is motivated by tangential interpolation. This addresses the challenge of fitting linear …
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