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[Illinois] ECE 564 Lecture 9
11 Apr 2016 | | Contributor(s):: Gabriel Popescu
[Illinois] ECE 564: Modern Light Microscopy
Current research topics in modern light microscopy: optics principles (statistical optics, Gaussian optics, elastic light scattering, dynamic light scattering); traditional microscopy (bright field, dark field, DIC, phase contract, confocal, epi-fluorescence, confocal fluorescence); current...
[Illinois] ECE 564 Lecture 2
05 Apr 2016 | | Contributor(s):: Gabriel Popescu
05 Feb 2016 | | Contributor(s):: Scott Michael Louis Slone, Chris Maffeo, AbderRahman N Sobh, Aleksei Aksimentiev
Tool workflow for building DNA Brick structures automatically.
[Illinois] Engineering the Mode Coupling in Microrings for Laser and Sensor Applications
11 Feb 2016 | | Contributor(s):: Lynford Goddard
The integrated microring Bragg reflector forms the basis of a new family of compact reflective photonic devices. The buildup of field strength in the high quality factor ring resonator configuration yields multiple reflection encounters with the same set of gratings. This enables high...
Data-Centric Models for Multilevel Algorithms
05 Feb 2016 | | Contributor(s):: Samuel Guiterrez
Today, computational scientists must contend with a diverse set of supercomputer architectures that are capable of exposing unprecedented levels of parallelism and complexity. Effectively placing, moving, and operating on data residing in complex distributed memory hierarchies is quickly...
New FOSLS Formulation of Nonlinear Stokes Flow for Glaciers
05 Feb 2016 | | Contributor(s):: Jeffrey Allen
This talk describes two First-order System Least-squares (FOSLS) formulations of the nonlinear Stokes flow used to model glaciers and ice sheets. The first is a Stress formulation and the second a Stress-Vorticity formulation. Both use fluidity, which is the reciprocal of viscosity and avoid the...
Non-Blocking Conjugate Gradient Methods for Extreme Scale Computing
05 Feb 2016 | | Contributor(s):: Paul Eller
Many scientific and engineering applications use Krylov subspace methods to solve large systems of linear equations. For extreme scale parallel computing systems, the dot products in these methods (implemented using allreduce operations in MPI) can limit performance because they are a...
Preconditioning for Divergence-Conforming Discretizations of the Stokes Equations
05 Feb 2016 | | Contributor(s):: Thomas Benson
Recent years have seen renewed interest in the numerical solution of the Stokes Equations. Of particular interest is the use of inf-sup stable pairs of finite elements for which weak enforcement of the incompressibility condition implies strong enforcement as well, such as with BDMelements....
Range Decomposition: A Low Communication Algorithm for Solving PDEs on Massively Parallel Machines
05 Feb 2016 | | Contributor(s):: Tom Manteuffel
The Range Decomposition (RD) algorithm uses nested iteration and adaptive mesh refinement locally before performing a global communication step. Only several such steps are observed to be necessary before reaching a solution within a small multiple of discretization error. The target application...
A Fast Multigrid Approach for Solving the Helmholtz Equation with a Point Source
02 Feb 2016 | | 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...
A Massively Parallel Semicoarsening Multigrid for 3D Reservoir Simulation on Multi-core and Multi-GPU Architectures
02 Feb 2016 | | Contributor(s):: Abdulrahman Manea
In this work, we have designed and implemented a massively parallel version of the Semicoarsening Black Box Multigrid Solver , which is capable of handling highly heterogeneous and anisotropic 3D reservoirs, on a parallel architecture with multiple GPU’s. For comparison purposes, the...
A Multigrid Method for the Self-Adjoint Angular Flux Form of the Radiation-Transport Equation Based on Cellwise Block Jacobi Iteration
02 Feb 2016 | | 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...
A Performance Comparison of Algebraic Multigrid Preconditioners on GPUs and MIC
02 Feb 2016 | | 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...
A Scalable Algorithm for Inverse Medium Problems with Multiple Sources
02 Feb 2016 | | 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....
Application of Multigrid Techniques to Magnetic and Electromagnetic Systems
02 Feb 2016 | | 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,...
Compatible Relaxation Based Geometric-Algebraic Multigrid
02 Feb 2016 | | 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...
Discretization of Elliptic Differential Equations Using Sparse Grids and Prewavelets
02 Feb 2016 | | Contributor(s):: Christoph Pflaum
Sparse grids can be used to discretize second order elliptic differential equations on a d-dimensional cube. Using Galerkin discretization, we obtain a linear equation system with unknowns. The corresponding discretization error is in the -norm. A major difficulty in...
Geometric Multigrid for MHD Simulations with Nedelec Finite Elements on Tetrahedral Grids
02 Feb 2016 | | 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,...
High Dimensional Uncertainty Quantification via Multilevel Monte Carlo
02 Feb 2016 | | Contributor(s):: Hillary Fairbanks
Multilevel Monte Carlo (MLMC) has been shown to be a cost effective way to compute moments of desired quantities of interest in stochastic partial differential equations when the uncertainty in the data is high-dimensional. In this talk, we investigate the improved performance of MLMC versus...