Publications
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The inverse fast multipole method: using a fast approximate direct solver as a preconditioner for dense linear systems KU Leuven
Although some preconditioners are available for solving dense linear systems, there are still many matrices for which preconditioners are lacking, particularly in cases where the size of the matrix N becomes very large. Examples of preconditioners include incomplete LU (ILU) preconditioners that sparsify the matrix based on some threshold, algebraic multigrid preconditioners, and specialized preconditioners, e.g., Calder´on and other analytical ...
Fast hierarchical solvers for sparse matrices using extended sparsification and low-rank approximation KU Leuven
Inversion of sparse matrices with standard direct solve schemes is robust but computationally expensive. Iterative solvers, on the other hand, demonstrate better scalability but need to be used with an appropriate preconditioner (e.g., ILU, AMG, Gauss–Seidel) for proper convergence. The choice of an effective preconditioner is highly problem dependent. We propose a novel fully algebraic sparse matrix solve algorithm. The computational complexity ...
Application of the inverse fast multipole method as a preconditioner in a 3D Helmholtz boundary element method KU Leuven
We investigate an efficient preconditioning of iterative methods (such as GMRES) for solving dense linear systems Ax = b that follow from a boundary element method (BEM) for the 3D Helmholtz equation, focusing on the low-frequency regime. While matrix–vector products in GMRES can be accelerated through the low-frequency fast multipole method (LFFMM), the BEM often remains computationally expensive due to the large number of GMRES iterations. We ...
Mitigation of railway induced ground vibration by stiff wave barriers KU Leuven
© 2016, German Acoustical Society (DEGA). All rights reserved. Railway induced vibrations can be a source of annoyance for lineside residents. Within the frame of the EU FP7 project RIVAS, different mitigation measures on the transmission path have been investigated. This paper shows the potential of stiff wave barriers to reduce low frequency railway induced vibrations by means of field measurements and numerical simulations. In El Realengo ...
Efficient mesh deformation based on radial basis function interpolation by means of the inverse fast multipole method KU Leuven
Radial basis function interpolation is often employed in mesh deformation algorithms for unstructured meshes, for example in fluid–structure interaction or design optimization problems. This is known to be a robust methodology that results in high quality deformed meshes. The applicability of this method to large problems is currently hampered by its prohibitive computational cost, however, which is caused by the need to solve a dense system of ...
Reducing railway-induced ground--borne vibration by using open trenches and soft-filled barriers KU Leuven
© 2016 Elsevier Ltd. A trench can act as a barrier to ground vibration and is a potential mitigation measure for low frequency vibration induced by surface railways. However, to be effective at very low frequencies the depth required becomes impractical. Nevertheless, for soil with a layered structure in the top few metres, if a trench can be arranged to cut through the upper, soft layer of soil, it can be effective in reducing the most ...
Experimental and numerical evaluation of the effectiveness of a stiff wave barrier in the soil KU Leuven
© 2015 Elsevier Ltd. This paper discusses the design, the installation, and the experimental and numerical evaluation of the effectiveness of a stiff wave barrier in the soil as a mitigation measure for railway induced vibrations. A full scale in situ experiment has been conducted at a site in El Realengo (Spain), where a barrier consisting of overlapping jet grout columns has been installed along a railway track. This barrier is stiff compared ...