8,916 research outputs found
Accelerated Modeling of Near and Far-Field Diffraction for Coronagraphic Optical Systems
Accurately predicting the performance of coronagraphs and tolerancing optical
surfaces for high-contrast imaging requires a detailed accounting of
diffraction effects. Unlike simple Fraunhofer diffraction modeling, near and
far-field diffraction effects, such as the Talbot effect, are captured by
plane-to-plane propagation using Fresnel and angular spectrum propagation. This
approach requires a sequence of computationally intensive Fourier transforms
and quadratic phase functions, which limit the design and aberration
sensitivity parameter space which can be explored at high-fidelity in the
course of coronagraph design. This study presents the results of optimizing the
multi-surface propagation module of the open source Physical Optics Propagation
in PYthon (POPPY) package. This optimization was performed by implementing and
benchmarking Fourier transforms and array operations on graphics processing
units, as well as optimizing multithreaded numerical calculations using the
NumExpr python library where appropriate, to speed the end-to-end simulation of
observatory and coronagraph optical systems. Using realistic systems, this
study demonstrates a greater than five-fold decrease in wall-clock runtime over
POPPY's previous implementation and describes opportunities for further
improvements in diffraction modeling performance.Comment: Presented at SPIE ASTI 2018, Austin Texas. 11 pages, 6 figure
Simulation of reaction-diffusion processes in three dimensions using CUDA
Numerical solution of reaction-diffusion equations in three dimensions is one
of the most challenging applied mathematical problems. Since these simulations
are very time consuming, any ideas and strategies aiming at the reduction of
CPU time are important topics of research. A general and robust idea is the
parallelization of source codes/programs. Recently, the technological
development of graphics hardware created a possibility to use desktop video
cards to solve numerically intensive problems. We present a powerful parallel
computing framework to solve reaction-diffusion equations numerically using the
Graphics Processing Units (GPUs) with CUDA. Four different reaction-diffusion
problems, (i) diffusion of chemically inert compound, (ii) Turing pattern
formation, (iii) phase separation in the wake of a moving diffusion front and
(iv) air pollution dispersion were solved, and additionally both the Shared
method and the Moving Tiles method were tested. Our results show that parallel
implementation achieves typical acceleration values in the order of 5-40 times
compared to CPU using a single-threaded implementation on a 2.8 GHz desktop
computer.Comment: 8 figures, 5 table
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Preparing sparse solvers for exascale computing.
Sparse solvers provide essential functionality for a wide variety of scientific applications. Highly parallel sparse solvers are essential for continuing advances in high-fidelity, multi-physics and multi-scale simulations, especially as we target exascale platforms. This paper describes the challenges, strategies and progress of the US Department of Energy Exascale Computing project towards providing sparse solvers for exascale computing platforms. We address the demands of systems with thousands of high-performance node devices where exposing concurrency, hiding latency and creating alternative algorithms become essential. The efforts described here are works in progress, highlighting current success and upcoming challenges. This article is part of a discussion meeting issue 'Numerical algorithms for high-performance computational science'
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