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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

Estimativa do desempenho de tratores agrícolas em campo e pista a partir do ensaio dinamométrico / Estimate of the performance of agricultural tractors in field and track from dynamometric tests

Russini, Alexandre 22 March 2012 (has links)
The agricultural tractor allows to move and to pull machines and implements used during the execution of the activities to field. One of the largest problem refers to the acting of the tractor, the reason of a lot of questions between farmers and manufacturing companies. The perfomance determination is a much complex task, mainly when realized in field level, because the variables that should be analyzed are countless, inside of an extremely wide context. The solution found by a lot of researchers was the standardization through testings realized in concrete track, what shows unreliable results about the perfomance of the tractor in the field, besides they can be expensives. The aim of this work was to previse, through dynamometrics tests, the perfomance of an agricultural tractor of wheels in track and in the field, without appeal to the direct tests. The experiment was conducted in Federal University of Santa Maria, submitting a instrumented tractor to dynamic tests of traction in a paved surface and in the field, besides static tests, using an electric dynamometer with Foucault current. Through the use of equations, already conceptualized, was possible to create a interrelation between the following variables: torque and power of the engine, resistance to the rollover, wheel slipping, relation between the transmission relation and the tires dimensions, providing a way to estimate the power developed in the traction bar and the fuel consumption, with subsequent comparison with the dynamic tests. It was found by the correlation analysis, using obtained and estimated values, that there was a high correlation coefficient between the power traction observed in the track and in the field, relative to the estimated power (0.99 and 0.98) respectively.The equations estimating the fuel consumption presented a high adjustment for 90%, obtaining variation between the field treatments and the track in order to 1,19% and 2,09% respectively. Therefore, the estimate of the tractor performance can be made with high accuracy, just doing the dynamometric tests in laboratory, substituting the dynamic tests of field and track. / O trator agrícola permite movimentar e tracionar máquinas e implementos utilizados durante a realização das atividades a campo. Um dos maiores problemas refere-se ao desempenho do trator, razão de muitos questionamentos entre agricultores e empresas fabricantes. A determinação do desempenho é uma tarefa bastante complexa, principalmente quando realizada em nível de campo, pois inúmeras são as variáveis que devem ser analisadas, dentro de um contexto extremamente amplo. A solução encontrada por inúmeros pesquisadores foi a padronização através de ensaios realizados em pista de concreto, o que remete a resultados pouco precisos referindo-se ao comportamento do trator a campo, além de serem dispendiosos. O objetivo deste trabalho foi prever através de ensaios dinamométricos, o desempenho de um trator agrícola de rodas em pista e a campo, sem recorrer aos ensaios diretos. O experimento foi conduzido na Universidade Federal de Santa Maria, submetendo um trator instrumentado a ensaios dinâmicos de tração em superfície pavimentada e campo, além de ensaios estáticos, utilizando um dinamômetro elétrico de corrente de Foucault. Através do uso de equações, já conceituadas, pôde-se realizar a inter-relação das seguintes variáveis: torque e potência do motor, resistência ao rolamento, patinamento, relação de transmissão e dimensões dos pneus, obtendo-se uma estimativa da potência desenvolvida na barra de tração e consumo de combustível, com posterior comparação aos ensaios dinâmicos. Verificou-se através da análise de correlação, utilizando os valores obtidos e estimados, que houve um elevado coeficiente de correlação entre a potência de tração observada no campo e pista em relação à potência estimada, (0,99 e 0,98) respectivamente. As equações de estimativa do consumo de combustível apresentaram um ajuste superior a 90%, obtendo variação entre os tratamentos de campo e pista na ordem de 1,19% e 2,09% respectivamente. Portanto, a estimativa do desempenho de um trator pode ser feita com elevada exatidão, realizando-se o ensaio dinamométrico em laboratório, substituindo desta forma, os ensaios dinâmicos de campo e pista.
2

Výroba držáku magnetu / Production of the magnet holder

Kraval, Jiří January 2016 (has links)
This project developed within the engineering studies of M-STG submits a proposal of a production technology of production of the magnet holder made of DC03. Based on a literary study of the problem of cutting, drawing, bending and calculations manufacturing of the component in a production die was suggested. The production die uses a normalised component and is tightened on PE 100 crank press with nominal drawbar pull 1000 kN. The conclusion of the thesis deals with the economic benefit of the suggested manufacturing technology.
3

Study of Energy Neutrality in Kochi Metro Rail, India

Paul, Jeena January 2021 (has links)
Now a days, the society thinks about more sustainable and clean energy sources. Most of the countries in the world relay on non-renewable energy sources for the generation of electricity. This results in the scarcity of fossil fuels in future and also increases the production of carbon emissions. This thesis considers a metro system named Kochi Metro which is a rapid transit system serving in the city of Kochi in Kerala, India which uses renewable sources, mainly solar, for giving power to the Metro.In this thesis work, trying to analyze the measures adopted by Kochi Metro Rail project in potential reductions of energy consumption and energy generation both contributing to energy efficiency.With the help of Matlab, different levels of installed PV power are used to find out the possible self-usage, self-sufficiency, and energy neutrality of the system.
4

Analýza provozu trakční napájecí stanice / Hybrid AC/DC,AC/AC substation operation analysis

Lakomý, Marek January 2014 (has links)
The work analyzes the operation of hybrid substations. The first chapter provides an analysis of domestic traction systems and describes in detail specific station. The next chapter follows the first in a way in which obtained parameters are converted to parameters suitable for the simulation program and presents its results. The third chapter discusses the serial communication used in one switchgear and about voltage regulator that controls one high voltage field. The last chapter verifies the simulation results obtained from the second chapter with real measurement and direct comparison is also included.

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