905 resultados para Pavements, Flexible
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Dissertation presented to obtain the Doutoramento (Ph.D.) degree in Biochemistry at the Instituto de Tecnologia Qu mica e Biol ogica da Universidade Nova de Lisboa
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Com o progresso da tecnologia aeronáutica, a deslocação de pessoas e bens tornou-se bastante acessível para variados pontos de mundo, com espaço de tempo muito reduzido. Um dos motores essenciais deste avanço, concernente à mobilidade, é o transporte aéreo e a sua evolução. Este tipo de transporte requer a máxima segurança, sendo que um único acidente pode gerar centenas de vítimas. Atendendo a estas condições, a qualidade dos pavimentos aeroportuários é de grande importância para a segurança da movimentação das aeronaves em solo. Mas, por razões económicas e por vezes de espaço, perspetivas de novas construções perdem viabilidade comparativamente a soluções de reabilitação. A posição geográfica do aeroporto de Ondjiva faz com que seja um importante ponto de passagem entre a África do Sul e a Namíbia e, prevê-se que o número de voos que se efetuam no aeroporto cresça, sendo que o país está numa fase de grande evolução. O presente trabalho visa o conhecimento do processo de dimensionamento para pavimentos aeroportuários e soluções de correção para anomalias que possam apresentar, aplicando-os ao aeroporto de Ondjiva, em Angola. Atualmente, o aeroporto revela um grande desgaste das pistas de táxi, inadaptabilidade das cabeceiras face às cargas estáticas a que são submetidas e, largura insuficiente da pista para a aeronave de projeto, ou aeronave crítica, atendendo ao regulamento da ICAO (International Civil Aviation Organization). Para melhorar o conforto, a segurança e eficiência dos serviços aéreos, o dimensionamento do aeroporto deve obedecer aos princípios e regras da ICAO. Pretende-se também a modelação de uma solução de reforço para o pavimento existente, para que não seja necessário construir um aeroporto de raiz, minimizando custos. Após a realização do dimensionamento, foi estudada a sinalização horizontal e luminosa da pista, para que esteja em conformidade com as suas novas medidas.
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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
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Portuguese Science Foundation - project Electra PTDC/CTM/099124/2008 and the PhD grant SFRH/BD/45224. financial support: Professor E. Fortunato’s ERC 2008 Advanced Grant (INVISIBLE contract number 228144), “APPLE” FP7-NMP-2010-SME/262782-2 and “SMARTEC” FP7-ICT-2009.3.9/258203
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Micro/nano wrinkled patterns on cross-linked urethane/urea polymeric flexible free standing films with two soft segments, polypropylene oxide and polybutadiene, can be induced by UV-irradiation. The ability to write/erase these 3D structures, in a controlled manner, is the main focus of this work. The imprinting of the wrinkled structures was accomplished by swelling in an appropriate solvent followed by drying the membranes after the cross-linking process and UV irradiation. The surface tailoring of the elastomeric membranes was imaged by optical microscopy, scanning electronic microscopy and by atomic force microscopy. To erase the wrinkled structures the elastomers were swollen. The swelling as well as the sol/gel fraction and the UV radiation were tuned in order to control the wrinkles characteristics. It was found that the wrinkles wavelength, in the order of microns (1±0,25μm), was stamped by the UV radiation intensity and exposure time while the wrinkles' amplitude, in the order of nanometers (150-450 nm), was highly dependent on the swelling and sol/gel fraction. A prototype for volatile organic compounds detection was developed taking advantage of the unique 3D micro/nano wrinkles features.
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Logoplaste is a specialist in operating in-house industrial sites for manufacturing rigid plastic packaging containers. In developing countries, especially in Africa, the low income of consumers does not allow a widespread adoption of products typically sold in rigid plastic containers. In these countries the flexible packages are usually adopted as they allow for better ratios of cost/litter of product, particularly in smaller packages. Should Logoplaste offer this type of technology in order to expand into developing countries?
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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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This paper offers a new approach to estimating time-varying covariance matrices in the framework of the diagonal-vech version of the multivariate GARCH(1,1) model. Our method is numerically feasible for large-scale problems, produces positive semidefinite conditional covariance matrices, and does not impose unrealistic a priori restrictions. We provide an empirical application in the context of international stock markets, comparing the nev^ estimator with a number of existing ones.
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Fundação para a Ciência e a Tecnologia (FCT) - (PTDC/EBB-EBI/102266/2008 and SFRH/BD/43830/2008, respectively) and by European Community’s FP7/2007-2013 (grant agreement nº 270089)
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The airport pavement deteriorates during service due to traffic and climate effects therefore systematic monitoring is required in order to assess their structural and functional condition. The aim of this work is to present the methodologies used nowadays for airport pavement evaluation and to contribute to their improvement in structural analysis area The main aspects that are addressed are the application of the Ground Penetrating Radar (GPR) and the use of the Falling Weight Deflectometer (FWD) tests, for structural evaluation, and the use of the GRIP tester and the measurement of texture depth of the wearing course layer, for the functional evaluation of the runway. Also, freeware computer softwares used to design new runways (FAARFIELD and COMFAA) are presented and examples are given. Case studies are described both for structural and functional evaluation.
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In this thesis was investigated the radiation hardness of the building blocks of a future flexible X-ray sensor system. The characterized building blocks for the pixel addressing and signal amplification electronics are high mobility semiconducting oxide transistors (HMSO-TFTs) and organic transistors (OTFTs), whereas the photonic detection system is based on organic semiconducting single crystals (OSSCs). TFT parameters such as mobility, threshold voltage and subthreshold slope were measured as function of cumulative X-ray dose. Instead for OSSCs conductivity and X-ray sensitivity were analysed after various radiation steps. The results show that ionizing radiation does not lead to degradation in HMSO-TFTs. Instead OTFTs show instability in mobility which is reduced up to 73% for doses of 1 kGy. OSSC demonstrate stable detector properties for the tested total dose range. As conclusion, HMSO-TFTs and OSSCs can be readily employed in the X-ray detector system allowing operation for total doses exceeding 1 kGy of ionizing radiation.
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This chapter aims at developing a taxonomic framework to classify the studies on the flexible job shop scheduling problem (FJSP). The FJSP is a generalization of the classical job shop scheduling problem (JSP), which is one of the oldest NP-hard problems. Although various solution methodologies have been developed to obtain good solutions in reasonable time for FSJPs with different objective functions and constraints, no study which systematically reviews the FJSP literature has been encountered. In the proposed taxonomy, the type of study, type of problem, objective, methodology, data characteristics, and benchmarking are the main categories. In order to verify the proposed taxonomy, a variety of papers from the literature are classified. Using this classification, several inferences are drawn and gaps in the FJSP literature are specified. With the proposed taxonomy, the aim is to develop a framework for a broad view of the FJSP literature and construct a basis for future studies.