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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.
131

Health Monitoring for Aircraft Systems using Decision Trees and Genetic Evolution

Gerdes, Mike January 2019 (has links) (PDF)
Reducing unscheduled maintenance is important for aircraft operators. There are significant costs if flights must be delayed or cancelled, for example, if spares are not available and have to be shipped across the world. This thesis describes three methods of aircraft health condition monitoring and prediction; one for system monitoring, one for forecasting and one combining the two other methods for a complete monitoring and prediction process. Together, the three methods allow organizations to forecast possible failures. The first two use decision trees for decision-making and genetic optimization to improve the performance of the decision trees and to reduce the need for human interaction. Decision trees have several advantages: the generated code is quickly and easily processed, it can be altered by human experts without much work, it is readable by humans, and it requires few resources for learning and evaluation. The readability and the ability to modify the results are especially important; special knowledge can be gained and errors produced by the automated code generation can be removed. A large number of data sets is needed for meaningful predictions. This thesis uses two data sources: first, data from existing aircraft sensors, and second, sound and vibration data from additionally installed sensors. It draws on methods from the field of big data and machine learning to analyse and prepare the data sets for the prediction process.
132

Production 4.0 of Ring Mill 4 Ovako AB

Hassan, Muhammad January 2020 (has links)
Cyber-Physical System (CPS) or Digital-Twin approach are becoming popular in industry 4.0 revolution. CPS not only allow to view the online status of equipment, but also allow to predict the health of tool. Based on the real time sensor data, it aims to detect anomalies in the industrial operation and prefigure future failure, which lead it towards smart maintenance. CPS can contribute to sustainable environment as well as sustainable production, due to its real-time analysis on production. In this thesis, we analyzed the behavior of a tool of Ringvalsverk 4, at Ovako with its twin model (known as Digital-Twin) over a series of data. Initially, the data contained unwanted signals which is then cleaned in the data processing phase, and only before production signal is used to identify the tool’s model. Matlab’s system identification toolbox is used for identifying the system model, the identified model is also validated and analyzed in term of stability, which is then used in CPS. The Digital-Twin model is then used and its output being analyzed together with tool’s output to detect when its start deviate from normal behavior.
133

Rekonstrukce železniční stanice Svitavy / Reconstruction of Railway Station Svitavy

Marek, Josef January 2022 (has links)
The goal of this thesis was to design the reconstruction of the railway station Svitavy. The line speed was rised from the current value to 160 km·h-1. New platforms were designed, therefore the railway substructure and the drainage were adjusted accordingly. Also, the effective length of the main tracks was extended to 740 m.
134

[pt] PLANEJAMENTO DA EXPANSÃO DA TRANSMISSÃO CONSIDERANDO SISTEMAS DE ARMAZENAMENTO DE ENERGIA / [en] TRANSMISSION EXPANSION PLANNING CONSIDERING ENERGY STORAGE SYSTEMS

JUAN PABLO LEAL GONZALEZ 11 January 2019 (has links)
[pt] O planejamento da expansão da transmissão (PET) visa identificar novos reforços para a rede, permitindo uma conexão tecnicamente adequada entre demanda e geração de energia elétrica, ambas previstas para um determinado horizonte de planejamento. Um bom plano de expansão deve garantir o equilíbrio entre os custos de investimento e operação, mantendo um nível satisfatório de segurança no fornecimento de energia elétrica. Entretanto, a identificação de bons planos de expansão para o PET tem se tornado uma tarefa cada vez mais difícil. Isso se deve, principalmente, às características e dimensões dos sistemas atuais, a não linearidade e natureza combinatória do problema de otimização e às incertezas presentes nos dados. Os erros de previsão, a indisponibilidade de equipamentos e a disponibilidade dos recursos naturais são parâmetros que variam de forma aleatória e inserem um alto grau de incerteza nos sistemas elétricos, o qual aumenta proporcionalmente com o horizonte de planejamento. Uma das incertezas mais relevantes a ser gerenciada nas próximas décadas será a capacidade de geração oriunda de fontes renováveis, em particular as eólicas, devido à sua grande variabilidade. A utilização de dispositivos de armazenamento permitirá melhor aproveitamento dessas fontes e, portanto, torna-se necessário o desenvolvimento de ferramentas computacionais capazes de considerar tais dispositivos no problema PET. Esta dissertação apresenta uma nova metodologia de apoio ao problema PET inserindo armazenadores de energia elétrica para aumentar o aproveitamento de fontes renováveis no sistema. Isso, respeitando as restrições de segurança da rede, acompanhando à curva de demanda e levando em consideração as variáveis operativas destes dispositivos. A possibilidade de incluir sistemas de armazenamento de energia elétrica é avaliada através de uma análise custo-benefício. A metodologia proposta é aplicada a um sistema teste, submetido a diversas condições operativas, e os resultados obtidos são amplamente discutidos. / [en] The transmission expansion planning (TEP) aims at identifying new reinforcements for the network, allowing a technically adequate connection between demand and generation of electric energy, both foreseen for a given planning horizon. A good expansion plan must ensure a balance between investment and operating costs, while maintaining a satisfactory level of security of the electric energy supply. However, identifying good expansion plans for TEP has become an increasingly difficult task. This is mainly due to the characteristics and dimensions of the current systems, the nonlinearity and combinatorial nature of the optimization problem, and the uncertainties present in the data. Forecasting errors, equipment unavailability, and the availability of natural resources are parameters that vary in a random way and insert a high degree of uncertainty in the electrical system, which proportionally increases with the planning horizon. One of the most relevant uncertainties to be managed in the upcoming decades will be the generation capacity from renewable sources, particularly wind power, due to its great variability. Storage devices will allow better use of these sources and, therefore, it becomes necessary to develop computational tools capable of considering such devices in the TEP problem. This dissertation presents a new methodology to support the TEP problem by inserting electric energy storage to increase the use of renewable energy in the system, while respecting the security restrictions of the network, following the demand curve and taking into account the operational variables of these devices. The possibility of including electric energy storage systems is evaluated through a costbenefit analysis. The proposed methodology is applied to a test system, subject to various operating conditions, and the obtained results are widely discussed.
135

An Introductory Course in the Reading of Simple Graphic and Statistical Material for Use in Junior High Schools

McKenzie, Annie 01 January 1930 (has links) (PDF)
In the stories of olden times and in those of our own American Indians, we learned of the picture writing of primitive peoples. It became an early method of recording people's thoughts. This was a very useful method at a time when the race was young. This in turn was the beginning of our alphabet, later the beginning of shaping letters into words, and then word into sentences and paragraphs. As our world has grown older, new idea have come into use and we are no longer content to live as our grandparents lived. We travel by fast express trains, high powered auto- mobiles, airplanes, or zeppelins. The radio gives us the news before our papers containing it are on the street. are not able to talk with people on the other side of the world. Business men find this a very valuable means of doing business when time means money. The motion pictures bring us the story of the book we have not had time to read and the characters from its pages talk to us from the screen. In short, we must have quicker ways of doing things.
136

Partner satisfaction and renewal likelihood in consumer supported agriculture (CSA) : a case study of The Equiterre CSA network

Achuo, George January 2003 (has links)
No description available.
137

Žiju tarot / I Live Tarot

Oplatková, Hana January 2012 (has links)
Private deck of cards created during six-month survey and documentation of daily experiences. The package contains 49 cards and it is inspired by a set of 78 tarot cards. Text content - reverse side of the card was created using diary notes. Face side of the card was chosen as a representation of processes taking place usually in days when the card was read.
138

Partner satisfaction and renewal likelihood in consumer supported agriculture (CSA) : a case study of The Equiterre CSA network

Achuo, George January 2003 (has links)
No description available.

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