17 resultados para Condition based maintenance (CBM)


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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação

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Dissertação apresentada como requisito parcial para obtenção do grau de Mestre em Estatística e Gestão de Informação.

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Pavements require maintenance in order to provide good service levels during their life period. Because of the significant costs of this operation and the importance of a proper planning, a pavement evaluation methodology, named Pavement Condition Index (PCI), was created by the U.S. Army Corps of Engineers. This methodology allows for the evaluation of the pavement condition along the life period, generally yearly, with minimum costs and, in this way, it is possible to plan the maintenance action and to adopt adequate measures, minimising the rehabilitation costs. The PCI methodology provides an evaluation based on visual inspection, namely on the distresses observed on the pavement. This condition index of the pavement is classified from 0 to 100, where 0 it is the worst possible condition and 100 the best possible condition. This methodology of pavement assessment represents a significant tool for management methods such as airport pavement management system (APMS) and life-cycle costs analysis (LCCA). Nevertheless, it has some limitations which can jeopardize the correct evaluation of the pavement behavior. Therefore the objective of this dissertation is to help reducing its limitations and make it easier and faster to use. Thus, an automated process of PCI calculation was developed, avoiding the abaci consultation, and consequently, minimizing the human error. To facilitate also the visual inspection a Tablet application was developed to replace the common inspection data sheet and thus making the survey easier to be undertaken. Following, an airport pavement condition was study accordingly with the methodology described at Standard Test Method for Airport Pavement Condition Index Surveys D5340, 2011 where its original condition level is compared with the condition level after iterate possible erroneous considered distresses as well as possible rehabilitations. Afterwards, the results obtained were analyzed and the main conclusions presented together with some future developments.

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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

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Text based on the paper presented at the Conference "Autonomous systems: inter-relations of technical and societal issues" held at Monte de Caparica (Portugal), Universidade Nova de Lisboa, November, 5th and 6th 2009 and organized by IET-Research Centre on Enterprise and Work Innovation

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Dissertation presented at Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa to obtain the Master degree in Electrical and Computer Engineering

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In developed countries, civil infrastructures are one of the most significant investments of governments, corporations, and individuals. Among these, transportation infrastructures, including highways, bridges, airports, and ports, are of huge importance, both economical and social. Most developed countries have built a fairly complete network of highways to fit their needs. As a result, the required investment in building new highways has diminished during the last decade, and should be further reduced in the following years. On the other hand, significant structural deteriorations have been detected in transportation networks, and a huge investment is necessary to keep these infrastructures safe and serviceable. Due to the significant importance of bridges in the serviceability of highway networks, maintenance of these structures plays a major role. In this paper, recent progress in probabilistic maintenance and optimization strategies for deteriorating civil infrastructures with emphasis on bridges is summarized. A novel model including interaction between structural safety analysis,through the safety index, and visual inspections and non destructive tests, through the condition index, is presented. Single objective optimization techniques leading to maintenance strategies associated with minimum expected cumulative cost and acceptable levels of condition and safety are presented. Furthermore, multi-objective optimization is used to simultaneously consider several performance indicators such as safety, condition, and cumulative cost. Realistic examples of the application of some of these techniques and strategies are also presented.

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Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores

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Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

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Dissertation to obtain the degree of Master in Electrical and Computer Engineering

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RESUMO: A confiabilidade e qualidade dos resultados clínicos de um laboratório, estão dependentes da qualidade do equipamento onde estes são processados. A qualidade de um equipamento consiste em apresentar resultados com uma confiabilidade metrológica de acordo com os processos de medição realizados. Desta forma, os equipamentos de medição devem conter características metrológicas de acordo com os requisitos dos processos que estão inseridos, tais como: erro máximo, incerteza, resolução… Todos os equipamentos por muito bons que sejam, apresentam perdas das suas características metrológicas ao longo do tempo, o que se torna importante a determinação periódica das suas calibrações, manutenções e o seu respectivo ajuste. A periodicidade das calibrações, devem ser baseadas, em critérios bem estabelecidos de modo a evitar a ocorrência da não conformidade, devido às medições com os equipamentos fora das suas especificações, garantindo-se assim, a confiabilidade metrológica e o aumento da produtividade devido ao controlo dos processos, evitando-se desta forma qualquer tipo de avaria por parte destes. Os normativos de Qualidade e Certificação estabelecem como requisito a calibração dos equipamentos de medição em intervalos adequados, mas não definem claramente qual o intervalo adequado. O importante é gerir as etapas de calibração e manutenção de acordo com os equipamentos de modo a garantir que os resultados emitidos por estes sejam mantidos em condições confiáveis, dentro do período entre calibrações e manutenções, de modo a que nãoocorra uma condição de falha, e por conseguinte, medições com grande quantidade de erros.------------ ABSTRACT: The reliability and quality of the results of a clinical laboratory, are dependent on the quality of the equipment where they are processed. The quality of a product is to present results with a metrological reliability according to the measuring processes carried out. Thus, measuring equipment must contain metrological characteristics according to the requirements of the processes that are included, such as: maximum error, uncertainty, resolution ... All equipment for very good they are, show losses of its metrological characteristics over time, it becomes important to determine its periodic calibrations, maintenance and its adjustment. The frequency of calibrations should be based on well-established criteria in order to avoid the occurrence of non-compliance due to the measurements with the equipment beyond its specifications, thus ensuring the metrological reliability and increased productivity due to the control of processes, thus avoiding any kind of damage on the part thereof. The normative and Quality Certification as a requirement to establish calibration of measuring equipment at appropriate intervals, but not clearly stipulate the proper range. It is important to manage the steps of calibration and maintenance equipment according to ensure that the results emitted by these conditions are maintained in trusted within the period between calibrations and maintenance, sothat there occurs a fault condition, and therefore, large amount of measurements with errors.

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3rd Historic Mortars Conference, 11-14 September 2013, Glasgow, Scotland

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The main purpose of the research is to present a proposal for a methodology to support the rehabilitation project of renders of old buildings in Portugal. To achieve the objective it was considered essential to define the main types of participants and aspects to integrate the proposal. The research methodology consists in an inquiry presented to professional participants in rehabilitation, a market study of materials and products available in Portugal, the design of a methodology proposal and its application to a case study. The inquiry sample totals 24 answers from the targeted professionals. A sequence of relevant supporting procedures consists in the proposal, which aims to provide a supporting methodology to decide and project in this context and also to be tested with its application to the building. This proposal was applied to an old building with load-bearing stone masonry walls and air-lime based renders. It was concluded that the assessment of the building and external renderings’ condition, its diagnosis and of the supporting walls, the definition of intervention, the specification of materials to be used and performance requirements to comply, and also plans for conservation and periodic maintenance, are crucial. From the inquiry, compatibility between materials and complementary roles and points of view of different types of participants in rehabilitation must be highlighted. A proposal for a methodology to support the project could provide useful guidance particularly for architects and construction engineers, and improve the understanding of direct participants on site, therefore contributing for the correct implementation of intervention.

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The main purpose of the research is to present a proposal for a methodology to support the rehabilitation project of renders of old buildings. To achieve the objective it was considered essential to define the main types of participants and aspects to integrate the proposal. The research methodology consists in an inquiry presented to several professional participants in rehabilitation, a market study of materials and products available in Portugal, the design of a methodology proposal and its application to a case study. The inquiry sample totals 24 answers from the targeted professionals. A sequence of relevant supporting procedures consists in the proposal, which aims to provide a supporting methodology to decide and project in this context and also to be tested with its application to the building. This proposal was applied to an old building with load-bearing stone masonry walls and air-lime based renders. It was concluded that the assessment of the building and external renderings’ condition, its diagnosis and of the supporting walls, the definition of intervention, the specification of materials to be used and performance requirements to comply, and also plans for conservation and periodic maintenance, are crucial. From the inquiry, compatibility between materials and complementary roles and points of view of different types of participants in rehabilitation must be highlighted. A proposal for a methodology to support the project could provide useful guidance particularly for architects and construction engineers, and improve the understanding of direct participants on site, therefore contributing for the correct implementation of the intervention.