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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simula??o computacional de medidas estereol?gicas em estruturas de metal duro (WC-Co)

Esteves, Ezequias Matos 22 August 2011 (has links)
Made available in DSpace on 2014-12-17T14:07:08Z (GMT). No. of bitstreams: 1 EzequiasME_TESE.pdf: 4077046 bytes, checksum: 10fbafe209b02444fb805640364b456c (MD5) Previous issue date: 2011-08-22 / This work focuses on the creation and applications of a dynamic simulation software in order to study the hard metal structure (WC-Co). The technological ground used to increase the GPU hardware capacity was Geforce 9600 GT along with the PhysX chip created to make games more realistic. The software simulates the three-dimensional carbide structure to the shape of a cubic box where tungsten carbide (WC) are modeled as triangular prisms and truncated triangular prisms. The program was proven effective regarding checking testes, ranging from calculations of parameter measures such as the capacity to increase the number of particles simulated dynamically. It was possible to make an investigation of both the mean parameters and distributions stereological parameters used to characterize the carbide structure through cutting plans. Grounded on the cutting plans concerning the analyzed structures, we have investigated the linear intercepts, the intercepts to the area, and the perimeter section of the intercepted grains as well as the binder phase to the structure by calculating the mean value and distribution of the free path. As literature shows almost consensually that the distribution of the linear intercepts is lognormal, this suggests that the grain distribution is also lognormal. Thus, a routine was developed regarding the program which made possible a more detailed research on this issue. We have observed that it is possible, under certain values for the parameters which define the shape and size of the Prismatic grain to find out the distribution to the linear intercepts that approach the lognormal shape. Regarding a number of developed simulations, we have observed that the distribution curves of the linear and area intercepts as well as the perimeter section are consistent with studies on static computer simulation to these parameters. / Este trabalho versa sobre a cria??o e as aplica??es de um software de simula??o din?mica para estudo da estrutura do metal duro (WC-Co). A base tecnol?gica utilizada para amplia??o da capacidade de hardware foi a GPU Geforce 9600 GT com o chip Physx criada com o prop?sito de dar mais realismo aos jogos eletr?nicos. O software simula a estrutura tridimensional do metal duro com o formato de uma caixa c?bica onde os carbetos de tungst?nio (WC) s?o modelados como prismas triangulares e prismas triangulares truncados. O programa se mostrou eficiente em testes de verifica??o, desde c?lculos de medidas de par?metros como na capacidade de amplia??o do n?mero de part?culas simuladas dinamicamente. Foi poss?vel fazer uma investiga??o de par?metros m?dios e de distribui??es de par?metros estereol?gicos utilizados para caracterizar a estrutura do metal duro atrav?s de planos de cortes. Nos planos de cortes das estruturas analisadas foram investigados os interceptos lineares, intercepto de ?rea e per?metro de se??o dos gr?os interceptados e a fase ligante da estrutura atrav?s do c?lculo do valor m?dio e da distribui??o do livre caminho. Como a literatura ? quase consensual que a distribui??o dos interceptos lineares ? lognormal e que isso sugere que a distribui??o dos gr?os na estrutura tamb?m seja lognormal, foi desenvolvida uma rotina no programa, que possibilitou uma investiga??o mais detalhada dessa quest?o. Foi observado que ? poss?vel, sob certos valores para os par?metros que definem o formato e tamanho do gr?o prism?tico, encontrar distribui??o de interceptos lineares que se aproximam do formato lognormal. Nas v?rias simula??es desenvolvidas foi verificado que as curvas de distribui??es de interceptos lineares, de ?rea e per?metro de se??o, est?o de acordo com trabalhos na literatura de simula??o computacional est?tica desses par?metros.
2

Modelagem e controle adaptativo de uma planta did?tica de n?vel com instrumenta??o industrial

Fonseca, Daniel Guerra Vale da 31 August 2012 (has links)
Made available in DSpace on 2014-12-17T14:56:07Z (GMT). No. of bitstreams: 1 DanielGVF_DISSERT.pdf: 2881772 bytes, checksum: 5236953fb6bb70560393eeeaa01f96f9 (MD5) Previous issue date: 2012-08-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The control, automation and optimization areas help to improve the processes used by industry. They contribute to a fast production line, improving the products quality and reducing the manufacturing costs. Didatic plants are good tools for research in these areas, providing a direct contact with some industrial equipaments. Given these capabilities, the main goal of this work is to model and control a didactic plant, which is a level and flow process control system with an industrial instrumentation. With a model it is possible to build a simulator for the plant that allows studies about its behaviour, without any of the real processes operational costs, like experiments with controllers. They can be tested several times before its application in a real process. Among the several types of controllers, it was used adaptive controllers, mainly the Direct Self-Tuning Regulators (DSTR) with Integral Action and the Gain Scheduling (GS). The DSTR was based on Pole-Placement design and use the Recursive Least Square to calculate the controller parameters. The characteristics of an adaptive system was very worth to guarantee a good performance when the controller was applied to the plant / As ?reas de controle, automa??o e otimiza??o contribuem para a melhoria dos processos utilizados pelas ind?strias, permitindo uma linha de produ??o r?pida, aprimorando a qualidade do produto final e reduzindo os custos de produ??o. Boas ferramentas para o desenvolvimento de pesquisas nestas ?reas s?o as plantas did?ticas, pois proporcionam um contato direto com equipamentos semelhantes ou at? mesmo usados no setor industrial. Em vista dessas capacidades, o objetivo deste trabalho ? modelar e controlar uma planta did?tica que consiste de um sistema de controle de processo para vaz?o e n?vel com instrumenta??o industrial. Com o modelo ? poss?vel construir um simulador capaz de permitir estudos a respeito do funcionamento do sistema, sem os gastos com a opera??o do processo real. ? o caso de experimentos com controladores, que podem ser testados diversas vezes antes de serem efetivamente utilizados no processo real. Dentre os diversos tipos de controladores existentes, foi dado foco aos de tipo adaptativo, principalmente ao auto-sintoniz?vel direto (Direct Self-Tuning Regulator DSTR) com a??o integral e ao controlador com Escalonamento de Ganho (Gain Scheduling GS). O controlador DSTR foi projetado com base no m?todo de posicionamento de p?los e teve seus par?metros calculados atrav?s da t?cnica dos m?nimos quadrados recursivos. As caracter?sticas dos sistemas adaptativos foram de grande valia para garantir um desempenho satisfat?rio dos controladores, quando aplicados ? planta

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