Whole array operations and array section operations are important features of many data-parallel languages. Efficient implementation of these operations on distributed- memory multicomputers is critical to the scalability and high-performance of data-parallel programs. This thesis presents an approach for analyzing communication patterns induced by array operations and for using run-time information to schedule the message flow. The distributed, dynamic scheduling algorithms guarantee link-contention-free data transfer and utilize network resources almost optimally. They incur little overhead, which is important in order not to reduce the speedup gained by the parallel execution. The algorithms can be used by compilers for the generation of efficient code for array operations. Implemented in a runtime library, they can derive a schedule depending on parameters passed by the parallel application. Simulation results demonstrate the algorithms' superiority to the asynchronous transfer mode that is commonly used for this type of communication.

We have conducted a performance analysis of a large scale multiprocessor system based on shared buses organized in a hierarchical fashion and employing an easy to implement snoopy cache protocol. · This arrangement, named TREEBUS [ 5], presents a logical extension path for multiprocessor systems based on a single shared bus whose scalability is limited by the available system bus bandwidth [26]. The multiple, independent, hierarchical buses overcome the bus bandwidth limitation and the architecture can scale to relatively large sizes. We have developed an easy to use, reasonably accurate and computationally efficient analytic model for analyzing the performance of the memory hierarchy. Our analysis presents a balanced view by incorporating cost and size of the memory subsystem, two parameters which can significantly impact the feasibility of this architecture. The results indicate that the TREEBUS can deliver high performance for a maximum of about 512 processors using available technology. For larger sizes, the problem is not the limited system bus bandwidth but the unmanageable size of the main memory and a deteriorating cost/performance ratio.

Orientador: Roberto Testezlaf / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-24T05:47:03Z (GMT). No. of bitstreams: 1 Mesquita_Marcio_D.pdf: 9242210 bytes, checksum: 01b3ff5b3006dbb1e240ffc605b33110 (MD5) Previous issue date: 2014 / Resumo: A falta de desenvolvimento técnico de projetos para filtros de areia utilizando ferramentas tecnológicas de engenharia limita a otimização das suas configurações e restringe o seu funcionamento eficiente, trazendo prejuízos energéticos, econômicos, e tornando mais longo o caminho para o aparecimento de inovações no processo de filtragem da água para a irrigação. Buscando contribuir para o desenvolvimento tecnológico e científico de um modelo de filtro de areia o objetivo geral dessa pesquisa foi contribuir para o aprimoramento do projeto estrutural desses equipamentos, colaborando com a padronização dos seus parâmetros de operação e gerando informações que auxiliem fabricantes no aperfeiçoamento de seus modelos de filtros. A metodologia dessa pesquisa foi divida em quatro etapas: (1) validação do uso da fluidodinâmica computacional em análises hidráulicas para filtros de areia; (2) análise do comportamento hidrodinâmico de modelos comerciais de placas difusoras e drenos no escoamento interno de filtros de areia; (3) projeto e dimensionamento de modelos originais de placa difusora e de dreno; e (4) construção e avaliação hidráulica de um protótipo de filtro de areia. Os resultados indicaram que, para as condições experimentais ensaiadas, a modelagem numérica parametrizada simulou com precisão o comportamento do escoamento de filtros de areia. O modelo de placa difusora projetada reduziu significativamente a velocidade do fluxo de entrada no filtro e aumentou a homogeneidade da distribuição das linhas de escoamento sobre a superfície do leito poroso. O protótipo de dreno proposto possibilitou a formação de linhas de fluxo radial e perpendicular na região de atuação do acessório, reduzindo o aparecimento de pontos de estagnação e vórtices e diminuindo a turbulência na entrada das suas aberturas. Adicionalmente, a proposição de um arranjo espacial para o sistema de drenagem aumentou a área efetiva de atuação de cada dreno, possibilitando uma expansão mais uniforme e homogênea do leito filtrante durante o fluxo ascendente e requerendo menores velocidades de fluidização para efetivação da retrolavagem. O protótipo de filtro de areia, desenvolvido a partir da aplicação das ferramentas de CFD, apresentou menor perda de pressão em relação aos equipamentos comerciais e para as condições de ensaios a que foram submetidos. Sobretudo, esse estudo permitiu validar a hipótese do emprego de ferramentas de CFD no projeto das dimensões, formato e o arranjo estrutural da placa difusora e de drenos em filtros de areia visando à melhor distribuição das linhas de fluxo, redução da perda de pressão durante os processos de filtragem e retrolavagem, diminuição das deformações superficiais da camada filtrante e maior homogeneidade de fluidização do leito durante a retrolavagem. Dessa forma, a técnica de fluidodinâmica computacional (CFD) mostrou-se adequada para projetos de novos componentes estruturais de filtros de areia, assim como para estudos sobre a sua dinâmica de funcionamento e operação / Abstract: The deficiency of technological development on sand filters design using engineering technological tools restricts its structure optimization and operation effectiveness, causing energy and economic losses. This condition contributes to make the upgrades in the irrigation filtration science a longer path. Searching to help the technological and scientific development of a sand filter model the objective of this research was to contribute to the structural design improvement of these equipment, collaborating with the standardization of its operating parameters and generating information to help manufacturers to improve their filter models. The research methodology was divided into four steps: (1) validation of the use of computational fluid dynamics in sand filters hydraulic analyzes; (2) analyses of the hydrodynamic behavior of commercial model of diffuser plates and drains in the sand filters inner flow; (3) design of innovative models of diffuser plate and drain; and (4) construction and hydraulic evaluation of a prototype of a sand filter. The results indicated that for the defined assessment conditions, the parameterized numerical model simulated the flow process with significant accuracy the sand filter hydrodynamic. The designed diffuser plate reduced significantly the filter inflow, increasing the uniformity the flow lines distribution on the porous media surface. The proposed underdrain model allowed the establishment of radial and perpendicular flow lines in the operating area near the drain, reducing the occurrence of stagnation points and vortexes and the turbulence close to the slots. The projected spatial arrangement of the drainage system increased the effective operation area of each drain, resulting in uniform and homogeneous expansion of the filter bed during the upward flow and requiring lower fluidization velocities values to accomplish the backwash process. The sand filter prototype, developed from the application of CFD tools, reduced the pressure loss in the trials conditions comparing to evaluated commercials equipment. Mainly, this research validated the hypothesis of CFD¿s tools application in the design of the dimensions, shape and the structural arrangement of the diffuser plate and drains for sand filters. This methodology allowed accomplishing the homogenization of flow lines, reducing the pressure loss during the filtering and backwash processes, decreasing the media superficial deformations and increase the homogeneity of the bed fluidization during the backwash. Consequently, the computational fluid dynamics technique (CFD) showed suitable for design applications on new structural components¿ of sand filters, as well to study its functioning and operation¿s dynamics / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

Orientadores: Vitor Rafael Coluci, Lubienska Cristina Lucas Jaquiê Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-22T12:49:14Z (GMT). No. of bitstreams: 1 NascimentoJunior_OrlandoSaraiva_M.pdf: 5339800 bytes, checksum: f37d5c4041d5404f5f45d33c5af054c5 (MD5) Previous issue date: 2013 / Resumo: Uma instalação hidráulica é um conjunto de dispositivos hidromecânicos e tubos com a função de transportar um fluido. O controle do escoamento deste fluido ocorre por meio de manobras nos dispositivos hidromecânicos. Uma investigação sobre o impacto das manobras destes dispositivos em uma instalação hidráulica pode evitar danos físicos ao sistema (como rompimento de tubos, por exemplo). Uma das formas de se investigar o efeito destas manobras é por meio da simulação. A simulação permite estudar um sistema hidráulico, que após uma manobra hidráulica sai de uma situação contínua (regime permanente inicial), entra em um estado transitório (regime transiente) para posteriormente entrar em uma nova situação contínua (regime permanente final). No regime de transiente hidráulico são formadas ondas de sobrepressão e subpressão internas na tubulação e que podem levar a danos. Um dos métodos mais aceitos para simulações de transiente hidráulico é o método das características, que permite transformar as equações diferenciais parciais que descrevem o fenômeno em um conjunto de equações diferenciais ordinárias. Dependendo do tamanho do sistema hidráulico (número e comprimento de tubos, número de dispositivos eletromecânicos, etc), o custo computacional pode ser elevado para se obter as informações sobre o comportamento do transiente. Neste trabalho aplicamos técnicas de computação paralela em placas de vídeos para processamento de propósito geral (GPU) e em multi-núcleos (OpenMP) para acelerar os cálculos do transiente hidráulico. Utilizamos um sistema hidráulico composto por um reservatório, uma válvula e um tubo e determinamos o ganho de desempenho em função do tamanho do tubo do sistema. A técnica OpenMP forneceu ganhos computacionais de até 3.3× enquanto a técnica envolvendo GPUs forneceu ganhos de 17×. Dessa forma, placas gráficas se mostraram muito interessantes para acelerar simulações de transientes hidráulicos com o método das características / Abstract: A hydraulic system is a set of hydromechanical devices and tubes designed to transport fluids through controlled operations. Investigating the impact of these operations on hydraulic systems can avoid physical damage to its parts (such as breakage of pipes, for example). One way to investigate these impacts is through computational simulations. The simulations allow to study a hydraulic system during initial and final steady states (after some device operation, for instance), and the transient state between them. During the hydraulic transient state, high and low pressure waves are formed in the tubes and are the main cause of tube damages. One of the most accepted methods for transient hydraulic simulations is the method of characteristics, which allows to transform the partial differential equations that describe the phenomenon in a set of ordinary differential equations. Depending on the size of the hydraulic system (number and length of tubes, number of electromechanical devices, etc), the computational cost to obtain information about the behavior of the transient can be large. In this work, we apply techniques of parallel computing involving video cards for general purpose processing (GPU) and multi-cores (OpenMP) to accelerate hydraulic transient calculations. We simulated a hydraulic system consisting of a reservoir, a valve and a pipe to determine the performance speedup as a function of the size of the pipe. The OpenMP technique provided computational speedup up to 3.3× whereas the GPU technique provided speedup of 17×. Therefore, our results indicated that GPUs are very interesting to accelerate hydraulic transients simulations using the method of characteristics / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

Electronic portfolio for mathematical problem solving in the elementary school is an authentic assessment tool for teachers and students to utilize in evaluating mathematical skills. It is a computer-based interactive software program to allow teachers to easily access student work in the problem solving area for assessment purposes, and to store multimedia work samples over time.

The parallelization and vectorization of Monte Carlo algorithms for modelling charge transport in semiconductor devices are considered. The standard ensemble Monte Carlo simulation of a three parabolic band model for GaAs is first presented as partial verification of the simulation. The model includes scattering due to acoustic, polar-optical and intervalley phonons. This ensemble simulation is extended to a full device simulation by the addition of real-space positions, and solution for the electrostatic potential from the charge density distribution using Poisson's equation. Poisson's equation was solved using the cloud-in-cell scheme for charge assignment, finite differences for spatial discretization, and simultaneous over-relaxation for solution. The particle movement (acceleration and scattering) and the solution of Poisson's are both separately parallelized. The parallelization techniques used in both parts are based on the use of semaphores for the protection of shared resources and processor synchronization. The speed increase results for parallelization with and without vectorization on the Ardent Titan II are presented. The results show saturation due to memory access limitations at a speed increase of approximately 3.3 times the serial case when four processors are used. Vectorization alone provides a speed increase of approximately 1.6 times when compared with the nonvectorized serial case. It is concluded that the speed increase achieved with the Titan II is limited by memory access considerations and that this limitation is likely to plague shared memory machines for the forseeable future. For the program presented here, vectorization is concluded to provide a better speed increase per day of development time than parallelization. However, when vectorization is used in conjunction with parallelization, the speed increase due to vectorization is negligible. / Graduation date: 1993