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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
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
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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
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
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
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Gupta, R. (author)
In this work we study the implementations of deflation and preconditioning techniques for solving ill-conditioned linear systems using iterative methods. Solving such systems can be a time-consuming process because of the jumps in the coefficients due to large difference in material properties. We have developed implementations of the iterative...
doctoral thesis 2015
document
Akram, M. (author), Jansen, K.M.B. (author), Bhowmik, S. (author), Ernst, L.J. (author)
Titanium and its alloys are usually bonded together using a high temperature resistant polyimide or epoxy adhesives. Such adhesives can withstand temperatures from 200°C to300°C. Earlier research work indicates that Surface modification of titanium with mechanical treatment and atmospheric pressure plasma treatment techniques leads to improved...
conference paper 2012
document
Collignon, T.P. (author)
This dissertation deals mainly with the design, implementation, and analysis of efficient iterative solution methods for large sparse linear systems on distributed and heterogeneous computing systems as found in Grid computing. First, a case study is performed on iteratively solving large symmetric linear systems on both a multi–cluster and a...
doctoral thesis 2011
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Gupta, R. (author), Vuik, C. (author), Lemmens, C.W.J. (author)
report 2010
document
De Wilde, J. (author), Baudrez, E. (author), Heynderickx, G. (author), Marin, G.B. (author)
Local preconditioning for Eulerian-Eulerian gas-solid flow calculations with variable gas density is investigated. The performance of simultaneous solution algorithms for low-Mach calculations is strongly related to preconditioning. The gas-solid drag source terms are at the origin of a solid volume fraction and frequency dependency of the...
conference paper 2006
document
Tang, J.M. (author), Vuik, C. (author)
Simulating bubbly flows is a very popular topic in CFD. These bubbly flows are governed by the Navier-Stokes equations. In many popular operator splitting formulations for these equations, solving the linear system coming from the discontinuous diffusion equation takes the most computational time, despite of its elliptic origins. Sometimes these...
conference paper 2006
document
Tang, J.M. (author), Vuik, C. (author)
Simulating bubbly flows is a very popular topic in CFD. These bubbly flows are governed by the Navier-Stokes equations. In many popular operator splitting formulations for these equations, solving the linear system coming from the discontinuous diffusion equation takes the most computational time, despite of its elliptic origins. Sometimes these...
conference paper 2006
document
Turkel, E. (author), Vatsa, V.N. (author), Swanson, R.C. (author), Rossow, C.C. (author)
We consider a multistage algorithm to advance in pseudo-time to find a steady state solution for the compressible Navier-Stokes equations. The rate of convergence to the steady state is improved by using an implicit preconditioner to approximate the numerical scheme. This properly addresses the stiffness in the discrete equations associated with...
conference paper 2006
document
Georgoulis, E.H. (author), Loghin, D. (author)
Standard (conforming) finite element approximations of convection-dominated convection-diffusion problems often exhibit poor stability properties that manifest themselves as non-physical oscillations polluting the numerical solution. Various techniques have been proposed for the stabilisation of finite element methods (FEMs) for convection...
conference paper 2006
document
Turkel, E. (author), Erlangga, Y.A. (author)
We consider acoustic scattering about a general body. This is described by the Helmholtz equation exterior to the body. In order to truncate the infinite domain we use the BGT absorbing boundary condition. The resultant problem in a finite domain is solved by a finite element procedure. This yields a large sparse system of linear equations which...
conference paper 2006
document
Tang, J.M. (author), Vuik, C. (author)
For various applications, it is well-known that deflated ICCG is an efficient method for solving linear systems with invertible and singular co-efficient matrix. This deflated ICCG with subdomain deflation vectors is used by us to solve linear systems with singular coefficient matrix, arising from a discretization of the Poisson equation with...
report 2006
document
Tang, J.M. (author)
In this report we give a short overview of aspects on parallel deflated conjugate gradient method which is applied on large, sparse, symmetric and semi-positive definite linear systems obtained from moving boundary problems. Moreover, we present some results of small numerical experiments. After introducing the Navier-Stokes equations for...
report 2005
document
Li, C. (author), Vuik, C. (author)
In this paper, some theoretical results on the eigenvalue analysis of the SIMPLER preconditioning for incompressible now is presented. Some formulations have been derived to characterize the spectrum of the preconditioned matrix. These results could be helpful for the practical use of the SIMPLER preconditioning. Some numerical tests are reported.
report 2003
document
Heldring, A. (author)
In this thesis, a full-wave analysis of electrically large reflector antennas (with a surface in the order of several thousands of square wavelengths) is presented. The mathematical model used for the analysis is the Electric Field Integral Equation (EFIE), applied to infinitely thin, Perfectly Conducting (PEC) surfaces. The Method of Moments ...
doctoral thesis 2002
document
Li, C. (author), Vuik, C. (author)
In this paper, an eigenvalue analysis of the SIMPLE preconditioning for incompressible flow is presented. Some formulations have been set up to characterize the spectrum of the preconditioned matrix. This leads to a generalized eigenvalue problem. The generalized eigenvalue problem is investigated. Some eigenvalue bounds and the estimation for...
report 2002
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