139 research outputs found
Structure driven multiprocessor compilation of numeric problems
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1991.Title as it appears in the Feb. 1991 M.I.T. Graduate List: Structure driven compilation of numeric problems.Includes bibliographical references (leaves 134-136).by G.N. Srinivasa Prasanna.Ph.D
Hierarchical N-Body problem on graphics processor unit
Galactic simulation is an important cosmological computation, and represents a classical N-body problem suitable for implementation on vector processors. Barnes-Hut algorithm is a hierarchical N-Body method used to simulate such galactic evolution systems.
Stream processing architectures expose data locality and concurrency available in multimedia applications. On the other hand, there are numerous compute-intensive scientific or engineering applications that can potentially benefit from such computational and communication models. These applications are traditionally implemented on vector processors.
Stream architecture based graphics processor units (GPUs) present a novel computational alternative for efficiently implementing such high-performance applications. Rendering on a stream architecture sustains high performance, while user-programmable modules allow implementing complex algorithms efficiently. GPUs have evolved over the years, from being fixed-function pipelines to user programmable processors.
In this thesis, we focus on the implementation of Barnes-Hut algorithm on typical current-generation programmable GPUs. We exploit computation and communication requirements present in Barnes-Hut algorithm to expose their suitability for user-programmable GPUs. Our implementation of the Barnes-Hut algorithm is formulated as a fragment shader targeting the selected GPU. We discuss implementation details, design issues, results, and challenges encountered in programming the fragment shader
High accuracy binary black hole simulations with an extended wave zone
We present results from a new code for binary black hole evolutions using the
moving-puncture approach, implementing finite differences in generalised
coordinates, and allowing the spacetime to be covered with multiple
communicating non-singular coordinate patches. Here we consider a regular
Cartesian near zone, with adapted spherical grids covering the wave zone. The
efficiencies resulting from the use of adapted coordinates allow us to maintain
sufficient grid resolution to an artificial outer boundary location which is
causally disconnected from the measurement. For the well-studied test-case of
the inspiral of an equal-mass non-spinning binary (evolved for more than 8
orbits before merger), we determine the phase and amplitude to numerical
accuracies better than 0.010% and 0.090% during inspiral, respectively, and
0.003% and 0.153% during merger. The waveforms, including the resolved higher
harmonics, are convergent and can be consistently extrapolated to
throughout the simulation, including the merger and ringdown. Ringdown
frequencies for these modes (to ) match perturbative
calculations to within 0.01%, providing a strong confirmation that the remnant
settles to a Kerr black hole with irreducible mass and spin $S_f/M_f^2 = 0.686923 \pm 10\times10^{-6}
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Mapping of recursive algorithms onto multi-rate arrays
In this dissertation, multi-rate array (MRA) architecture and its synthesis are proposed
and developed. Using multi-coordinate systems (MCS), a unified theory for mapping
algorithms from their original algorithmic specifications onto multi-rate arrays is
developed.
A multi-rate array is a grid of processors in which each interconnection may have its
own clock rate; operations with different complexities run at their own clock rate, thus
increasing the throughput and efficiency.
A class of algorithms named directional affine recurrence equations (DARE) is
defined. The dependence space of a DARE can be decomposed into uniform and non-uniform
subspaces. When projected along the non-uniform subspace, the resultant array
structure is regular. Limitations and restrictions of this approach are investigated and a
procedure for mapping DARE onto MRA is developed.
To generalize this approach, synthesis theory is developed with initial specification
as affine direct input output (ADIO) which aims at removing redundancies from algorithms.
Most ADIO specifications are the original algorithmic specifications. A multi-coordinate
systems (MCS) is used to present an algorithm's dependence structures. In a
MCS system, the index spaces of the variables in an algorithm are defined relative to their own coordinate systems. Most traditionally considered irregular algorithms present regular dependence structures under MCS technique. Procedures are provided for transforming algorithms from original algorithmic specifications to their regular specifications.
Multi-rate schedules and multi-rate timing functions are studied. The solution for multi-rate timing functions can be formulated as linear programming problems. Procedures are provided for mapping ADIOs onto multi-rate VLSI systems. Examples are provided to illustrate the synthesis of MRAs from DAREs and ADIOs.
The first major contribution of this dissertation is the development of the concrete, executable MRA architectures. The second is the introduction of MCS system and its application in the development of the theory for synthesizing MRAs from original algorithmic specifications
Visualizing the memory performance of parallel programs with Chiron
Bibliography: leaves 78-81.This thesis describes Chiron, visualization system which helps programmers detect memory system bottlenecks in their shared-memory parallel applications. Chiron is different from most other performance debugging tools in that it uses three-dimensional graphics techniques to display vast amounts of memory-performance data. Both code-and data-oriented information can be presented in several views. These views have been designed to help the user detect problems which cause coherence interference or replacement interference. Chiron’s interactive user-interface enables the user to manipulate the views and home in on features which indicate memory system bottlenecks. The visualized data can be augmented with more detailed numerical and correlations between the separate views can be displayed. The effectiveness of Chiron is illustrated in this thesis by means of three case studies
Computational Methods in Science and Engineering : Proceedings of the Workshop SimLabs@KIT, November 29 - 30, 2010, Karlsruhe, Germany
In this proceedings volume we provide a compilation of article contributions equally covering applications from different research fields and ranging from capacity up to capability computing. Besides classical computing aspects such as parallelization, the focus of these proceedings is on multi-scale approaches and methods for tackling algorithm and data complexity. Also practical aspects regarding the usage of the HPC infrastructure and available tools and software at the SCC are presented
Robust and affordable localization and mapping for 3D reconstruction. Application to architecture and construction
La localización y mapeado simultáneo a partir de una sola cámara en movimiento se conoce como Monocular
SLAM. En esta tesis se aborda este problema con cámaras de bajo coste cuyo principal reto consiste en ser
robustos al ruido, blurring y otros artefactos que afectan a la imagen. La aproximación al problema es discreta,
utilizando solo puntos de la imagen significativos para localizar la cámara y mapear el entorno. La principal
contribución es una simplificación del grafo de poses que permite mejorar la precisión en las escenas más
habituales, evaluada de forma exhaustiva en 4 datasets. Los resultados del mapeado permiten obtener una
reconstrucción 3D de la escena que puede ser utilizada en arquitectura y construcción para Modelar la Información
del Edificio (BIM). En la segunda parte de la tesis proponemos incorporar dicha información en un sistema de
visualización avanzada usando WebGL que ayude a simplificar la implantación de la metodologÃa BIM.Departamento de Informática (Arquitectura y TecnologÃa de Computadores, Ciencias de la Computación e Inteligencia Artificial, Lenguajes y Sistemas Informáticos)Doctorado en Informátic
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