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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.
281

An investigation into the application of formal decision making techniques to design Alterations and Additions (As&As) for vessels of the Royal Fleet Auxiliary (RFA)

Franks, D. A. January 2018 (has links)
The Royal Fleet Auxiliary (RFA) is a flotilla of ships, owned by the United Kingdom (UK) Ministry of Defence (MoD), which serves to resupply naval vessels during worldwide operations. Design Alterations and Additions (As&As) are implemented throughout their service lives in order to ‘Upgrade’ and ‘Update’ their capability. This research offers an original contribution to knowledge by applying formal decision making techniques to A&A reasoning in a way that, to the best knowledge of the researcher, has not previously been implemented as an integral part of the in-service design control process for RFA ships. In delivering this contribution, Multi Attribute Decision Making (MADM) techniques are investigated and applied. Three MADM techniques are applied: SAW (Simple Additive Weighting), AHP (Analytic Hierarchy Processes) and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution). Application of these techniques defines the scope boundary and so rules out exhaustive investigation into the wider decision making approaches that could form the focus of future research. Literature reviews indicate that formal decision techniques have been extensively studied and applied – seemingly to the point of saturation. For this reason, the research does not claim to have developed new techniques. Rather, the contribution to knowledge lies in the systematic application of the techniques. In this respect, a niche topic is identified involving the implementation of As&As during Fleet Time (FT). Investigation results in the systematic identification and categorisation of the Risk Factors (RFs) constraining FT implementation. Two different techniques (SAW and AHP) are applied to FT As&As. The outcomes demonstrate a consistent trend and so offer mutual assurance. In addition, comparison of the techniques indicates that, whilst SAW offers a convenient and intuitive approach, the AHP imposes a higher cognitive burden. This is regarded as significant by the researcher since As&As are subject to schedule and cost constraints, whereby pragmatic and proportional approaches are more likely to find programme acceptance. Based upon an actual decision involving the selection of materials for a ship sea water system, TOPSIS is used to evaluate the options against key criteria. A sensitivity analysis indicates that selection will be influenced in the direction of the criteria weighting. Since ‘procurement cost’ is an important criterion for As&As, the thesis demonstrates a methodology for the delivery of robust cost estimates. This involves the treatment of cost uncertainty using risk analysis software based upon the Monte Carlo technique. The researcher consolidates studies into systematic decision methodologies for As&As. Credibility is claimed since methodologies are based upon established techniques and tested against A&A examples. Credibility is also claimed from the theme, running throughout the thesis, that the studies build upon the professional experience of the researcher and involve engagement with Suitably Qualified and Experienced Personnel (SQEP).
282

Basic Studies on Persistent Current Compensator for Superconducting Magnet by Use of Linear Type Magnetic Flux Pump / リニア型磁束ポンプを適用した超伝導マグネット用永久電流補償装置に関する基礎研究 / リニアガタ ジソク ポンプ オ テキヨウシタ チョウデンドウ マグネットヨウ エイキュウ デンリュウ ホショウ ソウチ ニ カンスル キソ ケンキュウ

Chung, Yoon Do 25 September 2007 (has links)
学位授与大学:京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2864号 ; 請求記号: 新制/工/1421 ; 整理番号: 25549 / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13393号 / 工博第2864号 / 新制||工||1421(附属図書館) / 25549 / UT51-2007-Q794 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 小林 哲生, 准教授 中村 武恒 / 学位規則第4条第1項該当
283

Novel fabrication techniques for microfluidic based in-situ oceanographic nutrient sensors

Ogilvie, Iain R. G. January 2012 (has links)
This work presents an investigation into the production of components for in-situ oceanographic nutrient sensors. These devices are based on a micro fluidic chip platform, taking the lab-on-a-chip (LOC) system concept out of the laboratory and into a real world environment. The systems are designed to provide data on nutrient concentrations in the ocean and as such are built from robust low cost materials designed for deployments from 24 hours to 3 months. This report focuses on the challenges faced in designing a micro fluidic system for these harsh deployment situations including a study of the relevant literature to indicate short falls in current technologies. The aim of this work was to develop the next generation of micro fluidic chip based nutrient sensors. A novel solvent vapour bonding technique has been developed for the production of polymer based micro fluidic chips which produces robust chips while simultaneously reducing the surface roughness of the substrates during bonding. This has allowed micromilling of polymer substrates to quickly and easily develop new chip designs with optical quality features. The surface reduction technology has enabled development of a method to integrate absorbance cells into tinted PMMA devices which is also discussed. Integration of polymer membranes to produce valve and pump structures is discussed and a novel bonding technique for chemically robust Viton R membranes is demonstrated. The final chapter includes a discussion on system topologies, concentrating on the need for high resolution sampling and the implications on system design that arise. A novel multiplexed stop ow system is demonstrated. Questions about the role of traditional micro fluidic components, such as mixers, in high-throughput low temporal response system designs are discussed and a micro fluidic mixer suitable for some of these systems demonstrated.
284

Development of an integrated soft cliff model to determine the impacts of environmental and climatic change on coastal recession

Carpenter, Natasha January 2014 (has links)
Understanding soft cliff systems is a significant challenge owing to the complex recession process and the need to quantify future responses to climate change. Process-based geomorphic modelling provides a key method for developing our understanding. However, existing models are frequently criticised for their simplified treatment of the cliff. Therefore, the overriding aim of this research was to contribute towards the development of a more integrated model. To facilitate this, this research has applied, evaluated and refined the SCAPE (Soft Cliff and Platform Erosion) model to a study frontage of variable lithology and coastal planshape on the south west coast of the Isle of Wight (UK). The initial model appraisal highlighted the need to further understand and quantify the role of variable material strength on shore platform geomorphology and rates of cliff toe retreat. The model was subsequently refined and demonstrated that outcropping layers of variable material resistance about mean sea level are a key control on the rates of cliff erosion, particularly for low sediment frontages. Weaker layers were found to result in an asymmetric increase in retreat in comparison to a more resistant layer of the same characteristics owing to the contrasting effects on the shore platform slope. This emphasises the importance of not extrapolating historic rates of retreat across frontages of variable lithology. Coastal management studies must consider relative changes in material resistance up the cliff face, the thickness of variable layers and the rate of sea-level rise to determine the magnitude of impact and duration of exposure.
285

Assessment of damage tolerance levels in FRP ship structures

Phillips, Holly Jacqueline January 1997 (has links)
This work is concerned with the damage tolerance assessment of laminated composite structures used in ship structures. An intensive review has been carried out with regard to current experimental, analytical and numerical work on both laminates and structural elements. Particular attention has been focused on the problem of damage due to delamination and its structural consequences. Strength assessments of top hat stiffeners and tee joints has been carried out with a view to identifying regions most susceptible to delaminations. It has been shown that such regions are contained within the curved region of the overlaminate in both types of structural elements. Strain energy release rates and J-integral values have been calculated for specific cracks to determine their likelihood of propagation under a variety of loading conditions. Overall, a number of conclusions have been drawn with regard to single-skin marine FRP structures. For example, both the strength - and the energy - based approaches have predicted that a tee joint subjected to a 45 degree pull-off load, delaminations which are deep within the overlaminate are more likely to propagate than those close to the surface.
286

Evaluation of the vertical and horizontal hydraulic conductivities of household wastes

Hudson, Andrew Philip January 2007 (has links)
Hydraulic conductivity is a measurement of the ease of movement of a fluid through a medium and is therefore a key parameter in the design of landfill leachate management systems. Hydraulic conductivity of landfilled wastes may be affected by several factors such as overburden stress from the weight of overlying waste, water content, the type, age and pre-processing of the waste, and the presence of landfill gas. A further factor that may affect leachate movement through wastes is the predominantly horizontal orientated structure of compacted wastes. This anisotropic structure may result in hydraulic conductivity in the horizontal direction being greater than that in the vertical direction. However existing research has been effectively limited to evaluating hydraulic conductivity in a single plane and so the presence of anisotropic flow in waste remains unproven. Consequently, modelling of leachate and contaminant movement in landfills may be compromised by the use of isotropic, or assumed anisotropic, hydraulic conductivity values. The object of this research has been to assess for the first time the inherent anisotropy of two different waste samples by measuring and comparing the vertical and horizontal hydraulic conductivities over a range of stresses typical of landfill conditions. In this thesis, factors affecting the measurement of hydraulic conductivity of wastes are discussed, and details of the samples tested and test methodology are given. The results of the tests are shown and alternative test methods are discussed. The effects of gas accumulation and pore water pressure on waste hydraulic conductivity encountered during testing are also reported as further research has developed from this important finding.
287

A resilience modelling approach for oil terminal operations under high uncertainties

Usman, A. Y. January 2017 (has links)
Oil terminals are complex infrastructures due to their diverse operational activities. They are exposed to diverse risks because they usually operate in a dynamic environment in which safety barriers are sometime overwhelmed, leading to the disruption of operations due to a high level of uncertainty. However, the ability of oil terminals to minimise vulnerability and maximise resilience depends on the availability of the correct anticipated information at the right time for a decision-making process. An important finding from the reviewed literature revealed that uncertainties and the unpredictability of the convergent effect of several hazardous factors have the potential to cause major disruptions such as fire, explosion and transit accidents. The consequences of these disruptions can lead to infrastructure damage and loss of life. The common operational threats to oil terminal operations (OTOs) substantiates the need for a holistic resilience model for operations in offshore/onshore terminals such as berthing/unberthing, vessel manoeuvring, loading and offloading, storage, etc. Due to the uncertainties associated with these operations and the cases of reported incidents/accidents, this research focuses more on the aspect of loading and offloading operations at ship/terminal interface. An emphasis on a resilience modelling approach provides a flexible yet robust model for OTOs to address disruption proactively, particularly with constantly evolving hazards and threats. This thesis introduces an innovative approach towards resilience modelling based on a developed novel framework. The key aspect of the framework was supported using three proposed models: (1) the integration of Utility Theory and Swiss Cheese Model (UtiSch_+), to evaluate the relative importance of the identified hazard factors (HFs), (2) a Bayesian network (BN), to calculate the overall probability that a specific hazard is present and, (3) an Analytical Hierarchical Process (AHP) - Prospect Theory (PT) approach, as an important model for a strategic decision selection method. An empirical study was conducted to test the validity the proposed models, using case studies and Sensitivity Analysis (SA). The result obtained demonstrated that the models are effective techniques to obtain the relative weight of the identified Hazard Factors (HFs) in order to prioritise them, for dynamic hazards probability evaluation and to prioritise suggested resilience strategies in order of importance to mitigate hazard/risk level. Evidently, the result revealed appears reasonable and appropriate for investment, in order to support a strategic decision for the selection of a resilience strategy for resilience improvement in OTOs.
288

Cintilografia miocárdica quantitativa com Tc-99m sestamibi e correção de atenuação : desenvolvimento de base de dados normal gênero-independente de estudos de perfusão miocárdica de estresse e validação multicêntrica em população de pacientes obesos

Grossman, Gabriel Leo Blacher January 2004 (has links)
Resumo não disponível
289

Estudo comparativo da viabilidade miocárdica em áreas dissinérgicas ao ecocardiograma basal : cintilografia tomográfica com Tecnécio 99m-mibi sob baixa dose de Dobutamina versus Tálio em repouso-redistribuição

Pilger Filho, Egon Pedro January 2000 (has links)
A cintilografia com radioisótopos em repouso tem despertado muito interesse nos últimos anos para pesquisa da viabilidade miocárdica na disfunção isquêmica avançada do VE, porque esta pode ser reversível e porque há melhora prognóstica neste contexto. O objetivo desse trabalho é buscar identificar a acurácia da cintilografia tomográfica Tc-99m-Sestamibi, sob a infusão de dobutamina em baixa dose. Foram protocolados trinta pacientes que sofreram um infarto do miocárdio com padrão “Q”, com dissinergia ao ecocardiograma, e submetidos a estudos perfusionais em dias diferentes, com Tc-99m-Sestamibi − dobutamina e Tl-201 em repouso-redistribuição 4 horas, usado como padrão ouro. Não ocorreram complicações com nenhum paciente submetido ao protocolo do estudo. Os resultados revelaram: sensibilidade = 85%, especificidade = 87%, valor preditivo positivo = 96%, valor preditivo negativo = 65 % e acurácia de = 85,2%. A razão de probabilidade positiva foi de 6,68 e a razão de probabilidade negativa de 0,17. Confrontando-se nossos dados com uma metanálise de resultados para o Tc-99m-Sestamibi em repouso, a sensibilidade no presente estudo foi 85% vs. 81% e a especificidade de 87% vs. 60%. Em relação aos dados da literatura para Tl-201: 85% vs. 90% e 87% vs. 54%, sensibilidade e especificidade, respectivamente. Em conclusão, o Tc-99m-Sestamibi sob a infusão de dobutamina parece ser um método promissor para detectar viabilidade superior a esta modalidade de cintilografia em repouso, com valores preditivos comparáveis à literatura disponível para esse mesmo método: 85,2% vs. 87%, 96% vs. 90% e 65% vs. 83%, para acurácia, valor preditivo positivo e valor preditivo negativo, respectivamente. / Rest isotopic scintigraphy has been evoked much interest in the last years for myocardial viability search on severe ischemic ventricular dysfunction, because improvement of function can bring a better outcome to this subset of acute myocardial infarction (MI) survivors. This study was designed to search to identify accuracy of 99m-Tc sestamibi − low dose dobutamine SPECT scintigraphy in a single injection rest protocol examination. Thirty patients with previous Q wave (MI), with basal echocardiographic demonstration of rest dyssynergia and coronary artery related significant obstruction, were submitted to perfusion studies, on a different day basis, with 99m-Tc-sestamibi − dobutamine and 201-Th rest-redistribution, utilized as gold standard. There were not complications with any patient submitted to this study protocol. The results showed sensitivity = 85%, specificity = 87%, positive predictive value = 96%, negative predictive value = 65% and accuracy = 85.2%. The positive likelihood ratio was 6.68 and the negative likelihood ratio 0.17. When our results were confronted with a metanalysis 99m-Tc sestamibi at rest (our results being firstly showed), sensitivity was 85% vs. 81%, specificity 87% vs. 60%, respectively. In relation to literature data for 201-Thallium were 85% vs. 90% e 87% vs. 54%, for sensitivity, specificity, respectively. In conclusion, 99m-Tc sestamibi-low dose dobutamine seems to be a promising test to detect viability, superior to that modality of rest perfusion, with predictive values comparable to the available literature for this methodology: 85,2% vs. 87%, 96% vs. 90% e 65% vs. 83%, results for accuracy, positive predictive value and negative predictive value, respectively.
290

Estudo da permeabilidade do epitélio pulmonar através da depuração do radioaerossol dietilenotriaminopentacético (DTPA) com o uso de pressão positiva expiatória nas vias aéreas (EPAP)

Albuquerque, Isabella Martins de January 2009 (has links)
Introdução: A taxa de depuração pulmonar do radioaerossol dietilenotriaminopentacético marcado com Tecnécio-99m (99mTc-DTPA) constitui um índice da permeabilidade do epitélio pulmonar. Vários estudos têm demonstrado o efeito da pressão positiva expiratória final (PEEP) na taxa de depuração do 99mTc-DTPA. A pressão positiva expiratória (EPAP), aplicada de forma não-invasiva, promove aumento do volume pulmonar. Objetivos: Avaliar o padrão da depuração pulmonar do radioaerossol do 99mTc-DTPA com o uso da EPAP e comparar os achados da depuração pulmonar do 99mTc-DTPA em níveis diferentes de EPAP (10 cmH2O, 15 cmH2O e 20 cmH2O). Determinar se a altura, o índice de massa corporal (IMC) e o gênero dos indivíduos interferem no tempo de meia-vida (T½) do complexo 99mTc-DTPA. Métodos: Realizou-se um ensaio clínico randomizado, unicego, no qual os voluntários foram submetidos à cintigrafia pulmonar com radioaerossol de 99mTc- DTPA em duas etapas: cintigrafia em respiração espontânea e respiração sob suporte ventilatório por EPAP (RHDSON Vital Signs®, New Jersey, EUA). Foram estudados 30 indivíduos hígidos adultos jovens (15 do sexo feminino e 15 do sexo masculino, média de idade 28,26 ± 5,40 anos) que constituíram o Grupo 1 - EPAP 10 cmH2O (n = 10); Grupo 2 - EPAP 15 cmH2O (n = 10) e Grupo 3 - EPAP 20 cmH2O (n = 10). O radioaerossol 99mTc-DTPA foi administrado durante três minutos através de um aparelho portátil específico para inalação pulmonar de aerossóis radioativos (Aerogama®, Medical, Porto Alegre, RS, Brasil). Imediatamente após o término da nebulização foi realizada a contagem sequencial da radioatividade de tórax, através de uma gama-câmara de cintilação tipo Anger (Starcam 4000i, GE, EUA). Todos os indivíduos foram submetidos ao teste espirométrico para atestar a normalidade da função pulmonar. Resultados: Houve aumento da taxa de depuração do 99mTc-DTPA (T½) somente quando 15 cmH2O de EPAP foi aplicada (p = 0,001), porém com o emprego de 10 cmH2O (p = 0,097) e 20 cmH2O (p = 0,124) de EPAP não houve alteração do T½ 99mTc-DTPA. Nos indivíduos do sexo feminino, o T½ foi de 74.40 ± 35.40 minutos e no sexo masculino de 74.36 ± 29.82 minutos, não havendo variação significante da taxa de depuração desse composto entre os sexos (p = 0,80). Ao correlacionar as variáveis altura (r = 0,085, p = 0,655) e IMC (r = 0,120, p = 0,528) com o T½ do radioaerossol 99mTc-DTPA não foi constatada correlação significante entre tais variáveis e a taxa de depuração pulmonar do 99mTc-DTPA. Conclusões: O presente trabalho descreveu pela primeira vez o efeito de diferentes níveis de EPAP sobre a taxa de depuração do radioaerossol 99mTc-DTPA, mostrando que somente a EPAP de 15 cmH2O reduziu o T½ do 99mTc-DTPA, enquanto que a aplicação de níveis pressóricos de 10 cmH2O e 20 cmH2O de EPAP não reduziram. Acredita-se que a insuflação pulmonar gerada pela pressão positiva de 15 cmH2O ocasione aumento na taxa de depuração do epitélio alveolar ao 99mTc-DTPA por produzir descontinuidades nas junções intercelulares do epitélio pulmonar. Esses resultados podem refletir o efeito da insuflação pulmonar sobre a perfusão dos capilares pulmonares alveolares e extra-alveolares o que afeta diretamente a depuração do radioaerossol de 99mTc-DTPA.

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