Searched for: subject%3A%22preconditioning%22
(1 - 20 of 65)

Pages

document
Quinlan, Alex (author)
One of the most well-established codes for modeling non-linear Magnetohydrodynamics (MHD) for tokamak reactors is JOREK, which solves these equations with a Bézier surface based finite element method. This code produces a highly sparse but also very large linear system. The main solver behind the code uses the Generalized Minimum Residual Method...
master thesis 2023
document
Buwalda, F.J.L. (author), de Goede, Erik (author), Knepflé, Maxim (author), Vuik, Cornelis (author)
The accuracy, stability and computational efficiency of numerical methods on central processing units (CPUs) for the depth-averaged shallow water equations were well covered in the literature. A large number of these methods were already developed and compared. However, on graphics processing units (GPUs), such comparisons are relatively scarce....
journal article 2023
document
Ji, Y. (author), Chen, K. (author), Möller, M. (author), Vuik, Cornelis (author)
Constructing an analysis-suitable parameterization for the computational domain from its boundary representation plays a crucial role in the isogeometric design-through-analysis pipeline. PDE-based elliptic grid generation is an effective method for generating high-quality parameterizations with rapid convergence properties for the planar...
journal article 2023
document
Vandenplas, Jeremie (author), Nguyen, B. (author), Vuik, Cornelis (author)
In this paper, we consider a block Jacobi preconditioner and various deflation techniques applied in the Deflated Preconditioned Conjugate Gradient (DPCG) method for solving a sparse system of linear equations derived from a statistical linear mixed model that analyses simultaneously phenotypic and pedigree information of genotyped and...
journal article 2023
document
Hoofwijk, Jorn (author)
In finite element software one has to solve a system of non-linear equations, which is commonly simplified to a sequence of linear system. We research the possibility to solve these systems on a GPU to improve the solve time. We are particularly interested in systems arising from geotechnical models. We compare several combinations of Krylov...
master thesis 2022
document
Vakili, Seryas (author), Ebadi, G. (author), Vuik, Cornelis (author)
In this article, a parameterized extended shift-splitting (PESS) method and its induced preconditioner are given for solving nonsingular and nonsymmetric saddle point problems with nonsymmetric positive definite (1,1) part. The convergence analysis of the (Formula presented.) iteration method is discussed. The distribution of eigenvalues of...
journal article 2022
document
Nguyen, Buu-Van (author)
The single-step single nucleotide polymorphism best linear unbiased prediction (ssSNPBLUP) model can potentially be used in animal breeding for genetic evaluations. It has been reported that this model has convergence issues when the Preconditioned Conjugate Gradient (PCG) method is applied. This is due to the linear system being ill-conditioned...
master thesis 2021
document
Maquelin, Eva (author)
Numerical methods are investigated for solving large-scale sparse linear systems of equations, that can be applied to thermo-mechanical models and wafer-slip models. This thesis examines efficient numerical methods, in terms of memory, number of iterations required for convergence, and computation time. To be more specific, algebraic multigrid ...
master thesis 2021
document
Koolstra, Kirsten (author), Remis, R.F. (author)
Purpose: To learn a preconditioner that accelerates parallel imaging (PI) and compressed sensing (CS) reconstructions. Methods: A convolutional neural network (CNN) with residual connections was used to train a preconditioning operator. Training and validation data were simulated using 50% brain images and 50% white Gaussian noise images....
journal article 2021
document
Dhingra, Kriti (author)
Magnetic Resonance Imaging is a painless procedure to produce high-resolution diagnostic images. Today, it is one of the essential clinical imaging modalities. One of the major challenges involved with this imaging modality is its long scanning time. Parallel imaging in combination with compressed sensing has overcome this challenge to a great...
master thesis 2020
document
Dely, Alexandre (author), Andriulli, Francesco P. (author), Cools, K. (author)
The time domain-electric field integral equation (TD-EFIE) and its differentiated version are widely used to simulate the transient scattering of a time dependent electromagnetic field by a perfect electric conductor (PEC). The time discretization of the TD-EFIE can be achieved by a space-time Galerkin approach or, as it is considered in this...
journal article 2020
document
van Gemert, J.H.F. (author)
This dissertation describes how to design dielectric pads that can be used to increase image quality in Magnetic Resonance Imaging, and how to accelerate image reconstruction times using a preconditioner.<br/><br/>Image quality is limited by the signal to noise ratio of a scan. This ratio is increased for higher static magnetic field strengths...
doctoral thesis 2019
document
Sereeter, B. (author), van Westering, W.H.P. (author), Vuik, Cornelis (author), Witteveen, C. (author)
In this paper, we propose a fast linear power flow method using a constant impedance load model to simulate both the entire Low Voltage (LV) and Medium Voltage (MV) networks in a single simulation. Accuracy and efficiency of this linear approach are validated by comparing it with the Newton power flow algorithm and a commercial network design...
journal article 2019
document
Koolstra, K. (author), van Gemert, J.H.F. (author), Börnert, Peter (author), Webb, A. (author), Remis, R.F. (author)
Purpose: Design of a preconditioner for fast and efficient parallel imaging (PI) and compressed sensing (CS) reconstructions for Cartesian trajectories. Theory: PI and CS reconstructions become time consuming when the problem size or the number of coils is large, due to the large linear system of equations that has to be solved in l<sub>1<...
journal article 2019
document
Liu, Zeyu (author)
In order to solve linear system of equations obtained from numerical discretisation fast and accurate, preconditioning on the coefficient matrix is needed. In this thesis research, a preliminary study on preconditioning techniques suitable for Mimetic Spectral Element Method (MSEM) will be presented. The spectral limit change of some important...
master thesis 2018
document
Swart, Wouter (author)
The numerical simulation of brittle failure with nonlinear finite element analysis (NLFEA) remains a challenge due to robustness issues. These problems are attributed to the softening material behaviour and the iterative nature of the Newton-Raphson type methods used in NLFEA. However, robust numerical simulations become increasingly important,...
master thesis 2018
document
Baumann, M.M. (author)
Seismic Full-Waveform Inversion is an imaging technique to better understand the earth's subsurface. Therefore, the reflection intensity of sound waves is measured in a field experiment and is matched with the results from a computer simulation in a least-squares sense. From a computational point-of-view, but also from an economic view point,...
doctoral thesis 2018
document
Baumann, M.M. (author), Astudillo Rengifo, R.A. (author), Qiu, Y. (author), Ang, Y.M.E. (author), van Gijzen, M.B. (author), Plessix, R.E. (author)
In this work, we present a new numerical framework for the efficient solution of the time-harmonic elastic wave equation at multiple frequencies. We show that multiple frequencies (and multiple right-hand sides) can be incorporated when the discretized problem is written as a matrix equation. This matrix equation can be solved efficiently...
journal article 2018
document
He, X. (author), Vuik, Cornelis (author), Klaij, Christiaan M. (author)
The augmented Lagrangian (AL) preconditioner and its variant have been successfully applied to solve saddle point systems arising from the incompressible Navier-Stokes equations discretized by the finite element method. Attractive features are the purely algebraic construction and robustness with respect to the Reynolds number and mesh renement....
journal article 2018
document
Boitcov, Dmitrii (author)
Existing multiscale solvers use a sequence of aggressive restriction, coarse-grid correction and prolongation operators to handle low-frequency modes on the coarse grid. High-frequency errors are resolved by employing a smoother on the fine grid. Deflation preconditioning improves matrix properties, i.e., damps slowly varying errors,...
master thesis 2017
Searched for: subject%3A%22preconditioning%22
(1 - 20 of 65)

Pages