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  1. Hub Snub: Removing Vertices with High Degree from Coarse-grid Correction

    04 Feb 2016 | Online Presentations | Contributor(s): Geoffry Sanders

    Network scientists often employ numerical solutions to linear systems as subroutines of data mining algorithms. Due to the ill-conditioned nature of the systems, obtaining solutions with standard iterative methods is often prohibitively costly; current research aims to automatically construct...

  2. Compatible Relaxation Based Geometric-Algebraic Multigrid

    04 Feb 2016 | Online Presentations | Contributor(s): Fei Cao

    We develop compatible relaxation algorithms for smoothed aggregation-based multigrid coarsening. In the proposed method, we use the geometry of the given discrete problem on the finest level to coarsen the system together with compatible relaxation to from the sparsity structure of the...

  3. A Fast Multigrid Approach for Solving the Helmholtz Equation with a Point Source

    04 Feb 2016 | Online Presentations | Contributor(s): Eran Treister

    Solving the discretized Helmholtz equations with high wave numbers in large dimensions is a challenging task. However, in many scenarios, the solution of these equations is required for a point source. In this case, the problem can be be reformulated and split into two parts: one in a solution...

  4. Task-Graph and Functional Programming Models: The New Paradigm

    04 Feb 2016 | Online Presentations | Contributor(s): Ben Bergen

    The Message Passing Interface (MPI) is an example of a distributed-memory communication model that has served us well through the CISC processor era. However, because of MPI's low-level interface, which requires the user to manage raw memory buffers, and its bulk-synchronous communication...

  5. Support Graph Smoothing Techniques

    04 Feb 2016 | Online Presentations | Contributor(s): Alyson Fox

    Many tasks in large-scale network analysis and simulation require efficient approximation of the solution to the linear system $ Lx=b$, where $ L$ is a graph Laplacian. However, due to the large size and complexity of scale-free graphs, standard iterative methods do not perform optimally. The...

  6. A Scalable Algorithm for Inverse Medium Problems with Multiple Sources

    04 Feb 2016 | Online Presentations | Contributor(s): Keith Kelly

    We consider the problem of acoustic scattering as described by the free-space, time-harmonic scalar wave equation given by   (0.1)   along with radiation boundary conditions. Here, is a point in , is the source term, and is the wavenumber. Our formulation is based on potential theory....

  7. HPGMG: Benchmarking Computers Using Multigrid

    04 Feb 2016 | Online Presentations | Contributor(s): Jed Brown

    HPGMG (https://hpgmg.org) is a geometric multigrid benchmark designed to measure the performance and versatility of computers. For a benchmark to be representative of applications, good performance on the benchmark should be sufficient to ensure good performance on most important applications...

  8. Parallel Multigrid Preconditioner Based on Automatic 3D Tetradedric Meshes

    04 Feb 2016 | Online Presentations | Contributor(s): Frederic Vi

    Multigrid methods are efficient for solving large sparse linear systems. Geometric (GMG) and Algebraic Multigrid (AMG) have both their own benefits and limitations. Combining the simplicity of AMG with the efficiency of GMG lead us to the development of an Hybrid Multigrid preconditionner. From...

  9. Geometric Multigrid for MHD Simulations with Nedelec Finite Elements on Tetrahedral Grids

    04 Feb 2016 | Online Presentations | Contributor(s): Chris Hansen

    The Magneto-HydroDynamic (MHD) model is used extensively to simulate macroscopic plasma dynamics in Magnetic Confinement Fusion (MCF) devices. In these simulations, the span of time scales from fast wave dynamics to the desired evolution of equilibrium due to transport processes is large,...

  10. Application of Multigrid Techniques to Magnetic and Electromagnetic Systems

    04 Feb 2016 | Online Presentations | Contributor(s): Benjamin Cowan

    We discuss the use of multigrid techniques for several novel systems related to electromagnetics. One of these is the magnetostatic problem, in which systems can involve highly anisotropic and nonlinear materials. We describe the linear problems arising in several variations of this problem,...

  11. Monolithic Multigrid Methods for Coupled Multi-Physics Problems

    04 Feb 2016 | Online Presentations | Contributor(s): Scott Maclachlan

    While block-diagonal and approximate block-factorization preconditioners are often considered for coupled problems, monolithic approaches can offer improved performance, particularly when the coupling between equations is strong. In this talk, we discuss the extension of Braess-Sarazin...

  12. A Performance Comparison of Algebraic Multigrid Preconditioners on GPUs and MIC

    04 Feb 2016 | Online Presentations | Contributor(s): Karl Rupp

    Algebraic multigrid (AMG) preconditioners for accelerators such as graphics processing units (GPUs) and Intel's many-integrated core (MIC) architecture typically require a careful, problem-dependent trade-off between efficient hardware use, robustness, and convergence rate in order to...

  13. Understanding the Propagation of Silent Data Corruption in Algebraic Multigrid

    04 Feb 2016 | Online Presentations | Contributor(s): Jon Calhoun

    Sparse linear solvers from a fundamental kernel in high performance computing (HPC). Exascale systems are expected to be more complex than systems of today being composed of thousands of heterogeneous processing elements that operate at near-threshold-voltage to meet power constraints. The...

  14. A Multigrid Method for the Self-Adjoint Angular Flux Form of the Radiation-Transport Equation Based on Cellwise Block Jacobi Iteration

    04 Feb 2016 | Online Presentations | Contributor(s): Jeffrey Densmore

    Cellwise block Jacobi iteration is a technique for radiation-transport calculations in which the angular flux for all directions is solved for simultaneously within a spatial cell with the angular flux in neighboring cells held fixed. Each step of the iteration then involves the inversion of a...

  15. Least-Squares Finite Element Method and Nested Iteration for Electromagnetic Two-Fluid Plasma Models

    04 Feb 2016 | Online Presentations | Contributor(s): Christopher Leibs

    Efforts are currently being directed towards a fully implicit, electromagnetic, JFNK-based solver, motivating the necessity of developing a fluid-based, electromagnetic, preconditioning strategy [1]. The two-fluid plasma (TFP) model is an ideal approximation to the kinetic Jacobian. The TFP...

  16. On the Design of a Finite Element Multigrid Solver for Mimetic Finite Difference Schemes

    04 Feb 2016 | Online Presentations | Contributor(s): Carmen Rodrigo

    The focus of this work is to study the relation between mimetic finite difference schemes on triangular grids and some finite element methods for two model problems based on curl-rot and grad-div operators. With this purpose, modified Nédélec and Raviart-Thomas finite element...

  17. A Massively Parallel Semicoarsening Multigrid for 3D Reservoir Simulation on Multi-core and Multi-GPU Architectures

    04 Feb 2016 | Online Presentations | Contributor(s): Abdulrahman Manea

    In this work, we have designed and implemented a massively parallel version of the Semicoarsening Black Box Multigrid Solver [1], which is capable of handling highly heterogeneous and anisotropic 3D reservoirs, on a parallel architecture with multiple GPU’s. For comparison purposes, the...

  18. [Illinois] Nanotechnology meets Biology in the Cancer Cell: Applications in Medicine, Drug Delivery, and Determining Drug Efficacy

    04 Feb 2016 | Online Presentations | Contributor(s): Mostafa El-Sayed

  19. Seventeenth Copper Mountain Conference on Multigrid Methods

    04 Feb 2016 | Workshops

    HIGHLIGHTED TOPICSUncertainty QuantificationOptimization and Inverse ProblemsData Mining, Large Graphs, and Markov ChainsNonsymmetric and Indefinite ProblemsKrylov AcceleratorsHybrid Direct-Iterative Linear SolversParallel Multigrid on Multicore Systems and Heterogeneous ArchitecturesTime...

  20. [Illinois] Bionanotechnology Seminar Series

    29 Jan 2016 | Series

    This series is organized by PhD students who are appointed as Trainees in the NIH/NCI Midwest Cancer Nanotechnology Training Center (M-CNTC) and in the NSF IGERT in Cellular and Molecular Mechanics and BioNanotechnology (CMMB IGERT). These traineeships are designed to train the next generation...