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1
Kuchenbecker, Emily E. "Lifetime." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5838.
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Time is my bully. Time marks the start of something, as well as the end. We are all carrying out the inexorable passing of time as it relates to our impending mortalities.
I do not fear death.
The awareness of my body’s impermanence employs me to feel that much more connected to the vessel containing that of which I am.
But what am I? Am I my body- or is it much deeper?
Through the work executed during my graduate research, I have attempted to quantify my existence through the archiving my time and body. This document ushers you through my perception, my relationship to nature, and how it manifests through discovering answers to what I believe it means to be human.
2
Alghamdi, Saeed Ahmad Ali Dobbah. "Discrete lifetime data." Thesis, University of Southampton, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494664.
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Madeira, Maria João da Costa. "Customer LifeTime Value." Master's thesis, FEUC, 2014. http://hdl.handle.net/10316/27594.
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Relatório de estágio do mestrado em Gestão, apresentado à Faculdade de Economia da Universidade de Coimbra, sob a orientação de Arnaldo Coelho, António Fery Antunes e António Oliveira Antunes.Este relatório tem por objetivo traduzir o passado em quatro meses de trabalho, o período do meu estágio curricular. O tema escolhido foi o Customer LifeTime Value (CLV), um assunto atual, que tem dado origem a inúmeros estudos conceptuais e empíricos. Com este projeto pretendo mostrar que a empresa onde realizei o meu estágio, Banco Comercial Português, S.A. está cada vez mais preocupada em investir no relacionamento com os seus clientes. Hoje em dia é impossível para setor dos serviços sobreviver sem uma estratégia focada no marketing relacional, em particular pretendo comprovar esta reflexão na instituição onde decorreu o meu estágio. Tendo o próprio conceito de marketing como o ponto de partida, irei começar o meu trabalho explicando as origens do marketing de relacionamento, um conceito focado no cliente e na sua satisfação, com o intuito de o fidelizar. A ideia não é completamente nova, desde as primeiras trocas comerciais reconhecia-se que manter uma relação com um cliente, que não fosse apenas uma simples troca esporádica, seria benéfico para ambas as partes. Assim, os clientes podem beneficiar de eventuais facilidades de pagamento, descontos e acima de tudo, um conhecimento prévio da qualidade do produto, enquanto os comerciantes beneficiam de lucro imediato. Hoje em dia, existem algumas empresas pequenas que conseguiram sobreviver graças à relação que eles têm vindo a construir com seus clientes ao longo dos anos. Em seguida abordarei a temática da lealdade como vínculo inevitável desta área de estudo. Apenas o desenvolvimento de uma relação de proximidade com o cliente por si só não basta, deve existir um esforço da entidade para o conseguir fidelizar, impulsionando nele a lealdade para com a instituição e/ou a marca. Tudo isto serve de base ao tema central deste estudo, o CLV. Investir num relacionamento estável pode dar origem a retornos significativos, adicionalmente ter a capacidade de prever com precisão o valor dos clientes trará inevitavelmente um enorme impacto sobre a capacidade de tomar decisões inteligentes. Esta é a lógica seguida pela metodologia CLV que detalharei. Os resultados obtidos permitem-me dizer que esta é uma empresa bem consciente da importância da área em estudo CLV, uma vez que faz uso de fatores relacionais, implementa-os ativamente na sua formulação estratégica como fontes de vantagem competitiva.
4
Nordfors, Per. "Prediction of Code Lifetime." Thesis, Linköpings universitet, Statistik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-135060.
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There are several previous studies in which machine learning algorithms are used to predict how fault-prone a piece of code is. This thesis takes on a slightly different approach by attempting to predict how long a piece of code will remain unmodified after being written (its “lifetime”). This is based on the hypothesis that frequently modified code is more likely to contain weaknesses, which may make lifetime predictions useful for code evaluation purposes. In this thesis, the predictions are made with machine learning algorithms which are trained on open source code examples from GitHub. Two different machine learning algorithms are used: the multilayer perceptron and the support vector machine. A piece of code is described by three groups of features: code contents, code properties obtained from static code analysis, and metadata from the version control system Git. In a series of experiments it is shown that the support vector machine is the best performing algorithm and that all three feature groups are useful for predicting lifetime. Both the multilayer perceptron and the support vector machine outperform a baseline prediction which always outputs the mean lifetime of the training set. This indicates that lifetime to some extent can be predicted based on information extracted from the code. However, lifetime prediction performance is shown to be highly dataset dependent with large error magnitudes.
5
Li, Xiang. "Lifetime prediction for rocks." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-126371.
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A lifetime prediction scheme is proposed based on the assumption that the lifetime (time to failure) of rocks under load is governed by the growth of microstructual defects (microcracks). The numerical approach is based on linear elastic fracture mechanics. The numerical calculation scheme is implemented as a cellular automat, where each cell contains a microcrack with length and orientation following certain distributions. The propagation of the microcrack is controlled by the Charles equation, based on subcritical crack growth. The zone inside the numerical model fails if the microcrack has reached the zone dimension or the stress intensity factor of the crack reached the fracture toughness. Macroscopic fractures are formed by these coalesced propagating microcracks, and finally lead to failure of the model. In the numerical approaches, elasto-plastic stress redistributions take place during the forming of the macroscopic fractures. Distinct microcrack propagation types have been programmed and applied to the proposed numerical models. These numerical models are studied under different loading conditions. Numerical results with excellent agreement with the analytical solutions are obtained with respective to predicted lifetime, important parameters for the microcracks, fracture pattern and damage evolution. Potential applications of the proposed numerical model schemes are investigated in some preliminary studies and simulation results are discussed. Finally, conclusions are drawn and possible improvements to the numerical approaches and extensions of the research work are given本文认为微结构缺陷（微裂纹）的扩展决定了受力岩石的寿命（破坏时间）。基于此假设，提出了岩石寿命预测方法。利用线弹性断裂力学理论，通过FLAC进行了数值模拟。数值模型中每个单元定义一条初始裂纹，其长度与方向服从特定分布。基于亚临界裂纹扩展理论，由Charles方程决定微裂纹的扩展（速度）。如微裂纹发展至单元边界，或应力强度系数到达断裂韧度，则单元破坏。宏观裂纹由微裂纹所联合形成，并最终贯穿模型导致破坏。在形成宏观裂纹的过程中，发生弹塑性应力重分布。在数值模型中，编制了不同类型的微裂纹扩展方式，并在不同的受力条件下加以分析。数值模型的岩石寿命，裂纹形状，破坏方式以及一些重要的参数的数值模拟结果与解析解有较好的一致性。对本文所提出的数值模型的初步实际应用进行了分析，并讨论了计算结果。最后讨论了本文所提出的岩石寿命预测方法的可能改良与发展，并对进一步的研究工作给出建议。
6
PAIXÃO, Ana Carla Percontini da. "New Extended Lifetime Distributions." Universidade Federal de Pernambuco, 2014. https://repositorio.ufpe.br/handle/123456789/12240.
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Este trabalho está dividido em quatro capítulos independentes. Nos Capítulos 2 e 3 propomos extensões para a distribuição Weibull. A primeira delas, com cinco parâmetros, é uma composição das distribuições beta e Weibull Poisson. Essa nova distribuição tem como submodelos algumas importantes distribuições descritas na literatura e outras ainda não discutidas tais como: bata exponencial Poisson, Weibull Poisson exponencializada, Rayleigh Poisson exponencializada, beta Weibull, Weibull, exponencial, entre outras. Obtemos algumas propriedades matemáticas tais como momentos ordinários e incompletos, estatísticas de ordem e seus momentos e entropia de Rényi. Usamos o método da máxima verossimilhança para obter estimativas dos parâmetros. A potencialidade desse novo modelo é mostrada por meio de um conjunto de dados reais. A segunda extensão, com quatro parâmetros, é uma composição das distribuições Poisson generalizada e Weibull, tendo a Poisson generalizada exponencial, a Rayleigh Poisson, Weibull Poisson e Weibull como alguns de seus sub-modelos. Várias propriedades matemáticas foram investigadas, incluíndo expressões explícitas para os momentos ordinários e incompletos, desvios médios, função quantílica, curvas de Bonferroni e Lorentz, con abilidade e as entropias de Rényi e Shannon. Estatísticas de ordem e seus momentos são investigados. A estimativa de parâmetros é feita pelo método da máxima verossimilhança e é obtida a matriz de informação obsevada. Uma aplicação a um conjunto de dados reais mostra a utilidade do novo modelo. Nos dois últimos capítulos propomos duas novas classes de distribuições. No Capítulo 4 apresentamos a família G- Binomial Negativa com dois parâmetros extras. Essa nova família inclui como caso especial um modelo bastante popular, a Weibull binomial negativa, discutida por Rodrigues et al.(Advances and Applications in Statistics 22 (2011), 25-55.) Algumas propriedades matemáticas da nova classe são estudadas, incluindo momentos e função geradora. O método de máxima verossimilhança é utilizado para obter estimativas dos parâmetros. A utilidade da nova classe é mostrada através de um exemplo com conjuntos de dados reais. No Capítulo 5 apresentamos a classe Zeta-G com um parâmetro extra e algumas nova distribuições desta classe. Obtemos expressões explícitas para a função quantílica, momentos ordinários e incompletos, dois tipos de entropia, con abilidade e momentos das estatísticas de ordem. Usamos o método da máxima verossimilhança para estimar os parâmetros e a utilidade da nova classe é exempli cada com um conjunto de dados reais.
7
Chan, Shek-lun Conan. "Adaptable housing in Hing Wah Estate II." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25948453.
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Bayrak, Hakan. "Lifetime Condition Prediction For Bridges." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613793/index.pdf.
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Infrastructure systems are crucial facilities. They supply the necessary transportation, water and energy utilities for the public. However, while aging, these systems gradually deteriorate in time and approach the end of their lifespans. As a result, they require periodic maintenance and repair in order to function and be reliable throughout their lifetimes. Bridge infrastructure is an essential part of the transportation infrastructure. Bridge management systems (BMSs), used to monitor the condition and safety of the bridges in a bridge infrastructure, have evolved considerably in the past decades. The aim of BMSs is to use the resources in an optimal manner keeping the bridges out of risk of failure. The BMSs use the lifetime performance curves to predict the future condition of the bridge elements or bridges. The most widely implemented condition-based performance prediction and maintenance optimization model is the Markov Decision Process-based models (MDP). The importance of the Markov Decision Process-based model is that it defines the time-variant deterioration using the Markov Transition Probability Matrix and performs the lifetime cost optimization by finding the optimum maintenance policy. In this study, the Markov decision process-based model is examined and a computer program to find the optimal policy with discounted life-cycle cost is developed. The other performance prediction model investigated in this study is a probabilistic Bi-linear model which takes into account the uncertainties for the deterioration process and the application of maintenance actions by the use of random variables. As part of the study, in order to further analyze and develop the Bi-linear model, a Latin Hypercube Sampling-based (LHS) simulation program is also developed and integrated into the main computational algorithm which can produce condition, safety, and life-cycle cost profiles for bridge members with and without maintenance actions. Furthermore, a polynomial-based condition prediction is also examined as an alternative performance prediction model. This model is obtained from condition rating data by applying regression analysis. Regression-based performance curves are regenerated using the Latin Hypercube sampling method. Finally, the results from the Markov chain-based performance prediction are compared with Simulation-based Bi-linear prediction and the derivation of the transition probability matrix from simulated regression based condition profile is introduced as a newly developed approach. It has been observed that the results obtained from the Markov chain-based average condition rating profiles match well with those obtained from Simulation-based mean condition rating profiles. The result suggests that the Simulation-based condition prediction model may be considered as a potential model in future BMSs.
9
Ratzlaff, Charles R. "Lifetime physical activity and osteoarthritis." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36735.
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Introduction: The overall goal of this thesis is to improve understanding of physical activity (PA), one of the most important, modifiable but controversial risk factors in osteoarthritis (OA). OA is the major public health problem in musculoskeletal medicine and leading cause of physical disability in older adults. The ultimate purpose is to provide evidence to inform OA prevention strategies, something not currently available.
Objectives: 1) To construct and describe lifetime trajectories of hip and knee joint force from physical activity in a large Canadian sample; 2) To validate self-report measures of medically-diagnosed OA and novel measures of joint vulnerability against clinical criteria; 3) To evaluate the relationship of lifetime joint force and hip and knee OA.
Methods: PA data were collected online from 4,269 subjects via a validated PA survey in a national population-based cohort from 2005 to 2007 and subjects ranked and lifetime trajectories plotted in terms of the ‘cumulative peak force index’, a novel joint force measure. Validation studies were conducted in a sub-sample. Population-based multivariable studies examining the relationship between joint force and incident hip and prevalent knee OA were conducted.
Results: 1) Overall women had slightly higher lifetime PA-related force then men. Six percent of subjects developed hip OA and seven percent knee OA during follow up. There was no risk from sport/recreational activity. Very high levels of total lifetime force (hip and knee), occupational force in men (knee) and household-related force in women (knee) were associated with an approximate 2-fold increase in risk of OA, as was previous joint injury (5-fold increase hip, 3-fold knee). At the knee, lower limb malalignment but not joint hypermobility, was associated with knee OA. Higher coordination was protective.
Conclusions: Taken collectively, the results show that lifelong physical activity-related joint force is generally safe for the hip and knee, and the promotion of exercise as a major public health initiative should continue without concern for increased rates of OA. Very high levels of occupational force in men and household force in women were risk factors for knee OA. Joint injury, lower limb malalignment and lower coordination were associated with OA.
10
Ven, Justin William van de. "Redistribution during the working lifetime." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408209.
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Louzada-Neto, Francisco. "Hazard models for lifetime data." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268248.
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Huang, Hui. "Lifetime prediction for power converters." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/54844/.
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Renewable energy is developing rapidly and gaining more and more commercial viability. High reliability of the generation system is essential to maximize the output power. The power inverter is an important unit in this system and is believed to be one of the most unreliable parts. In the case of wind power generation, especially in off-shore wind, when the system reliability requirement is high, a technique to predict the inverter lifetime is invaluable as it would help the inverter designer optimize his design for minimal maintenance. Previous researchers studying inverter lifetime prediction, focus either at device level such as device fatigue damage models, or at system level which require experimental data for their selected device. This work presents a new method to estimate the inverter lifetime from a given mission profile within a reasonable simulation time. Such model can be used as a converter design tool or an on-line lifetime estimation tool after being configured to a real converter system. The key contribution of this work is to link the physics of the power devices to a large scale system simulation within a reasonable framework of time. With this technique, the system down time can be reduced and therefore more power can be generated. Also, the failure damage to the system is avoided which reduces the maintenance cost. A power cycling test is designed to gather the lifetime data of a selected IGBT module. Die-attach solder fatigue is found out to be the dominant failure mode of this IGBT module. The accuracy of widely accepted Miner’s rule, which accumulates damage linearly, is discussed and a nonlinear accumulation method is promoted to predict the lifetime of power inverters.
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Kaimal, Kiren G. "Light: Journey of a Lifetime." ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/709.
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This thesis covers the lessons I've learned throughout film school and how I have applied them towards the making of my thesis film, the 12-minute narrative short, Light, shot on digital video. Every aspect of the filmmaking process is covered including my education at UNO and its application to my thesis. Areas covered include the writing process, pre-production, production, and post-production. The one area that is omitted is distribution, something that was not taught at UNO and something that I am in the process of doing. Keywords: Film Production MFA Short Film India Kerala
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Doumenc, Jean-marc. "The Place of a Lifetime." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15893/1/Jean-marc_Doumenc_Thesis.pdf.
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This autobiographic novella is part of longer novel, not yet written. The novel, "Le temps d'une vie", has three parts, corresponding to three periods in the life of the character. This novella is the first part of the novel.
The story takes place in a small village south of France, between the Mediterranean Sea and the vineyards. A child, then a teenager, comes to his grand parents' house for holidays: Christmas, Easter and the long summer break. He meets grand parents, aunts, and an uncle. For him and his friends, the whole village and the countryside around are their playground. He experiences a life there quite different from his regular one in the city of Bordeaux with his parents.
The novella was first written in French, then translated into English by Dr Siobhan Brownlie. The translator and I discussed various problems that arose, the main issue being dealing with culturally specific terms in the French text. The novella was judged by Dr Donna Lee Brien not as a translation but as an original piece of writing, and she made suggestions for changes to the English text. I implemented some of these changes in order to produce a further version of the English text and finding some of the suggestions useful for the French text too, I implemented corresponding changes in the French text.
Dr Siobhan Brownlie wrote a paper about the translation process of this thesis, "Original as Translation; Translation as Original". The paper has been published in "UQ Vanguard", 2003, mini-series #3.
Contact: UQ Vanguard, c/o Clubs and Societies, UQ Union, University of Queensland, St Lucia 4072.
uqvanguard@uq.edu.au;
www.emsah.uq.edu.au/uqvanguard
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Doumenc, Jean-marc. "The Place of a Lifetime." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15893/.
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This autobiographic novella is part of longer novel, not yet written. The novel, "Le temps d'une vie", has three parts, corresponding to three periods in the life of the character. This novella is the first part of the novel. The story takes place in a small village south of France, between the Mediterranean Sea and the vineyards. A child, then a teenager, comes to his grand parents' house for holidays: Christmas, Easter and the long summer break. He meets grand parents, aunts, and an uncle. For him and his friends, the whole village and the countryside around are their playground. He experiences a life there quite different from his regular one in the city of Bordeaux with his parents. The novella was first written in French, then translated into English by Dr Siobhan Brownlie. The translator and I discussed various problems that arose, the main issue being dealing with culturally specific terms in the French text. The novella was judged by Dr Donna Lee Brien not as a translation but as an original piece of writing, and she made suggestions for changes to the English text. I implemented some of these changes in order to produce a further version of the English text and finding some of the suggestions useful for the French text too, I implemented corresponding changes in the French text. Dr Siobhan Brownlie wrote a paper about the translation process of this thesis, "Original as Translation; Translation as Original". The paper has been published in "UQ Vanguard", 2003, mini-series #3. Contact: UQ Vanguard, c/o Clubs and Societies, UQ Union, University of Queensland, St Lucia 4072. uqvanguard@uq.edu.au; www.emsah.uq.edu.au/uqvanguard
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Ogunlu, Bilal. "Lifetime Analysis For Wireless Sensor Networks." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605226/index.pdf.
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Sensor technologies are vital today in gathering information about certain environments and wireless sensor networks are getting more widespread use everyday. These networks are characterized by a number of sensor nodes deployed in the field for the observation of some phenomena. Due to the limited battery capacity in sensor nodes, energy efficiency is a major and challenging problem in such power-constrained networks. Some of the network design parameters have a direct impact on the network&rsquos lifetime. These parameters have to be chosen in such a way that the network use its energy resources efficiently. This thesis studies these parameters that should be selected according to certain trade offs with respect to the network&rsquo
s lifetime. In this work, these trade offs have been investigated and illustrated in detail in various combinations. To achieve this goal, a special simulation tool has been designed and implemented in this work that helps in analyzing the effects of the selected parameters on sensor network&rsquo
s lifetime. OMNeT++, a discrete event simulator, provides the framework for the sensor network simulator&rsquo
s development. Ultimately, results of extensive computational tests are presented, which may be helpful in guiding the sensor network designers in optimally selecting the network parameters for prolonged lifetime.
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Rother, Wolfram [Verfasser]. "Lifetime Measurements in 62,64,66Fe / Wolfram Rother." München : Verlag Dr. Hut, 2011. http://d-nb.info/1012432068/34.
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Mazhar, Muhammad Ilyas Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Lifetime monitoring of appliances for reuse." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2006. http://handle.unsw.edu.au/1959.4/25963.
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Environmental awareness and legislative pressures have made manufacturers responsible for the take-back and end-of-life treatment of their products. Therefore, manufacturers are struggling to find ways to recover maximum value from returned products. This goal can best be achieved by promoting multiple reuse programs as reuse is one of the most effective ways to enhance a sustainable engineering economy. Since the essential goal of the reuse strategy is to reuse parts, the reliability of used parts becomes a core issue. Research indicates that reuse is technologically feasible, associated with a significant manufacturing cost saving, and it does not compromise product quality. However, it is not easy to be applied in reality. There are several uncertainties associated with reuse, the most common is the uncertainty of the product???s quality after use. A widespread implementation of the reuse strategy could be triggered, subject to the availability of reliable methods to assess the useful remaining life of parts. The evolution of such a methodology would play a pivotal role in making decisions on the supply chain process and the recovery value of returned products. Reliability assessment by life cycle data analysis is the basis of this research. The proposed methodology addresses the problem of reliability assessment of used parts by considering two important aspects. It performs statistical as well as condition monitoring data analysis for decision-making on reuse. The analysis is carried out in two stages. Firstly, a wellknown reliability assessment procedure, the Weibull analysis, is applied to analyse time-tofailure data to assess the overall reuse potential of components. In the second stage, the used capacity (actual life) of components is determined by analysing their operating history (condition monitoring data). The linear and nonlinear regression analysis, Kriging procedures and artificial neural networks (ANN) are employed in this stage. Finally, the Weibull analysis and ANNs are integrated to estimate the remaining useful life of components/assemblies of a product at the end of its first life cycle. The model was validated by using life cycle data from consumer products.
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Cole, Mary Janet. "Fluorescence lifetime imaging for biomedical applications." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393718.
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Niewelt, Tim [Verfasser], Eicke [Akademischer Betreuer] Weber, and Stefan [Akademischer Betreuer] Glunz. "Lifetime-limiting defects in monocrystalline silicon." Freiburg : Universität, 2017. http://d-nb.info/1178321479/34.
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Benjamin, Zev (Zev A. ). "Runtime verification of object lifetime specifications." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53102.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Includes bibliographical references (leaves 48-49).
This thesis reports on the implementation of a runtime verification system for object lifetime specifications. This system is used to explore and evaluate the expressiveness object lifetime specifications. Object lifetime specifications are program annotations that indicate, in terms of program execution, when objects should be reclaimed. Object lifetime specifications are designed to be used within the context of an object-oriented programming language with automatic storage reclamation (i.e., garbage collection). Our runtime verification system observes program execution and reports objects that are not re-claimed before the end of their specified lifetime. We implement our system with the Java Path Finder model-checking framework. JPF supports modeling non-determinism in programs. We leverage this support to verify all possible thread interleavings when checking user programs.
by Zev Benjamin.
M.Eng.
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TABLADA, Claudio Javier. "Generalized probability distributions for lifetime applications." Universidade Federal de Pernambuco, 2017. https://repositorio.ufpe.br/handle/123456789/23660.
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A arte da indução paramétrica a uma distribuição-base é um dos métodos mais usados para obter modelos mais versáteis. A principal razão para esta tendência é o fato de que, muitas vezes, modelos clássicos podem não ser suficientemente flexíveis para ajustar certos dados de tempos de vida. Assim, distribuições generalizadas ou estendidas são de grande importância, principalmente por duas razões: para ter maior controle nas caudas e para melhorar a bondade de ajuste da distribuição-base. Nesta tese, propomos duas novas famílias de distribuições, denominadas de famílias do supremo e do ínfimo, as quais acrescentam um parâmetro de forma a uma distribuição-base. Obtemos algumas propriedades e quantidades matemáticas dessas famílias. Além disso, apresentamos cinco modelos particulares pertencentes à família do supremo e outros cinco modelos pertencentes à família do ínfimo. Uma outra contribuição é um modelo de três parâmetros, denominado de distribuição Fréchet modificada, a qual é obtida acrescentando um parâmetro de forma no modelo Fréchet. Usando a função W de Lambert, obtemos várias quantidades e propriedades matemáticas deste modelo. Finalmente, propomos um modelo generalizado de quatro parâmetros, denominado de distribuição beta Marshall-OlkinLomax, obtido considerando a distribuição Lomax como modelo base no gerador beta Marshall-Olkin. Determinamos várias expansões úteis e propriedades matemáticas para este modelo. Em todos os casos, provamos empiricamente a aplicabilidade dos novos modelos a dados reais.
The art of parameter induction to a parent distribution is one of the methods more used for obtain more versatile models. The main reason for this trend is the fact that, many times, classic models often may not be flexible enough to adjust certain lifetime data. So, generalized or extended distributions are of great importance, mainly for two reasons: for controlling the tails and improve the goodness-of-fit of the parent distribution. In this thesis, we propose two new families of distributions, namely thesupremum and infimum families, which induce a shape parameter to a parent distribution. We obtain some properties and mathematical quantities of these families. In addition, we present five particular models belonging to the supremum family and others five models belonging to the infimum family. Other contribution is a three-parameter model called the modified Fréchet distribution, which is obtained by inducing a shape parameter in the Fréchet model. Using the Lambert W function, we obtain several mathematical quantities and properties of this model. Finally, we propose a four-parameter generalized model called the beta Marshall-Olkin Lomax distribution, which is obtained to considering the Lomax distribution as the parent model in the beta Marshall-Olkingerator. We obtain several useful expansions and mathematical properties for this model. In all cases, we prove empirically the applicability of the new models to real data.
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Ray, Mark D. "Precision Lifetime Measurements in Molecular Hydrogen /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487931512617771.
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Solomon, Cam Charles. "Melanoma and lifetime ultraviolet radiation exposure /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/10913.
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Strömberg, Mathias. "Lifetime assessment of complex industrial systems - A framework for renewal strategies." Licentiate thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1566.
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For technical systems in the electricity and paper and pulpindustries, asset management is emerging as a new approachaddressing how to exploit physical assets with long operativelives in the most profitably way. An important problem forasset management staff is knowing when to carry out areplacement or renewal. This is a difficult question whichrequires taking into consideration parameters of totallydifferent naturese.g. reliability data, operatingcosts, condition information from technical systems, theenvironment and rules and regulation. An incorrect estimate ofa residual lifetime can result in a premature renewal withaccompanying high capital costs. If, however, renewal isdelayed, a breakdown may occur which can cause major damage totechnical equipment and a loss of income due to outages.
This work presents a formal model that calculates expectedcosts of different long-term strategies when managing technicalsystems. It is shown that with relatively few inputs, which inmany cases are easy to collect or estimate, a good picture canbe developed that shows the amount of resources a company willneed in the future in terms of renewals of their technicalsystems. The foundation for this work is a case study and aliterature review; the objective was to study what methods andmodels are in use today when estimating residual lifetime oftechnical systems. Also, aspects that influence long-term assetmanagement were investigated. Lessons learned from the casestudy and literature review were then used to develop a dynamicmodel, the Dynamic Lifetime Analysis model (DLA model).
This model is based on a probabilistic and dynamic riskanalysis of a technical system, linking different aspects ofrisk management strategies to specific characteristics of thephysical system. Furthermore it is shown how this model,coupled with specific value judgments, can be used to designoptimal long-term strategies. When taking more than onetechnical system under consideration the model shows that it isnot always the most effective, from a system viewpoint, torenew it too close to a possible breakdown. If there is aperiod predicted to incur high investment, it can, at times, bebetter to do an early renewal thereby maintaining resources ata constant level. The thesis also describes how to work withlong-term strategic decisions in a structural manner in orderfor the actors on a deregulated market to stay competitive.
Key Words:Residual lifetime estimation, Assetmanagement, Maintenance, Technical systems in power and pulp-and paper industries, Long terms renewal strategies.
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Oura, P. (Petteri). "Search for lifetime determinants of midlife vertebral size:emphasis on lifetime physical activity and early-life physical growth." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215792.
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Abstract Osteoporotic vertebral fractures are common among ageing populations worldwide. Although small vertebral size has been established as an independent risk factor for vertebral fracturing, relatively few determinants of vertebral size are currently known. The present study aimed to reveal lifetime factors that associate with midlife vertebral size. Overall physical activity across the lifespan, sports participation in adulthood, occupational physical activities in adulthood, and physical growth in early life were investigated. A subsample of the Northern Finland Birth Cohort Study 1966 was used, with a 46-year follow-up (n = 1,540). Vertebral dimensions were obtained by magnetic resonance imaging of the lumbar spine at the age of 46. The present data showed that high lifelong leisure-time physical activity and active participation in high-impact sports in adulthood were associated with large midlife vertebral size among women, but no such association was detected among men. Occupational physical activities were not associated with vertebral size among either sex. Early-life weight gain predicted large midlife vertebrae among both sexes, and the effect of height gain on vertebral size seemed to be mediated by adult height. The present findings show that the female vertebra in particular seems to benefit from high leisure-time physical activity and active participation in high-impact sports. Regardless of sex, early development also seems to play a role in determining later-life vertebral size. Prospective studies should confirm the causality of the present findings, and further research is needed to shed light on other lifetime factors as determinants of vertebral sizeTiivistelmä Selkänikaman osteoporoottiset murtumat ovat maailmanlaajuisesti yleinen ikääntyvän väestön vaiva. Pienen nikamakoon tiedetään lisäävän nikamamurtuman riskiä, mutta nikamakokoon vaikuttavia tekijöitä tunnetaan toistaiseksi varsin vähän. Tämän tutkimuksen tavoitteena on selvittää keski-iän nikamakokoon vaikuttavia elinaikaisia tekijöitä. Erityisesti tutkitaan vapaa-ajan liikunnallisuuden, lajikohtaisen harrastusaktiivisuuden, työn liikunnallisten piirteiden sekä lapsuuden ja nuoruuden fyysisen kehityksen yhteyttä nikamakokoon. Tutkimusjoukkona käytetään osaotosta Pohjois-Suomen vuoden 1966 syntymäkohortista (n = 1 540). Seuranta-aika on ollut 46 vuotta, ja selkänikaman koko on määritetty tutkittavista 46 vuoden iässä otetuista lannerangan magneettikuvista. Tutkimusaineistossa naisten elinaikainen vapaa-ajan liikunnallisuus sekä aktiivinen luustoa kuormittavien liikuntalajien harrastaminen ovat yhteydessä suureen nikamakokoon keski-iässä. Miesten liikunnallisuuden ja nikamakoon välillä ei sen sijaan havaittu vastaavaa yhteyttä, eivätkä työn liikunnalliset piirteet olleet yhteydessä nikamakokoon kummallakaan sukupuolella. Varhainen painon kasvu ennusti suurta keski-iän nikamakokoa sukupuolesta riippumatta, ja varhaisen pituuskasvun vaikutus nikamakokoon näytti välittyvän aikuispituuden kautta. Tutkimuksen tulosten perusteella siis erityisesti naiset näyttäisivät hyötyvän vapaa-ajan liikunnallisesta aktiivisuudesta ja luuta kuormittavien lajien harrastamisesta aikuisiällä. Sukupuolesta riippumatta myös lapsuuden ja nuoruuden fyysisellä kehityksellä näyttäisi olevan merkitystä keski-iän nikamakokoon. Tulevaisuudessa prospektiivisten tutkimusasetelmien tulisi vahvistaa tässä tutkimuksessa havaittujen yhteyksien kausaliteetti. Lisäksi tutkimusta tarvittaisiin jatkossa muiden nikamakokoon vaikuttavien elinaikaisten tekijöiden selvittämiseksi
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Welty-Rieger, Leah. "The lifetime of a beautiful and charming meson B(c) meson lifetime measured using the D0 detector /." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337257.
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Thesis (Ph.D.)--Indiana University, Dept. of Physics, 2008.Title from PDF t.p. (viewed on Jul 28, 2009). Source: Dissertation Abstracts International, Volume: 69-12, Section: B, page: 7581. Adviser: Rick Van Kooten.
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Koien, Vivian Sporstøl. "Lifetime degradation in n-type Cz-Si." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19595.
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The main object was to investigate the effect of donors, thermal donors and defects on the lifetime on n-type Czochralsky (Cz) silicon. Cz is a technique for making monocrystals by dipping a monocrystalline seed into the melt, and pulling the ingot up as the melt solidifies. Samples were prepared by sawing, grinding and polishing. Copper decoration and preferential etching was done to reveal the defects. Resistivity measurements were performed to investigate the donor distribution. The lifetime and oxygen concentration was measured.The lifetime may be influenced by donors and traps. Traps may be metallic or non-metallic. Dopants and metal contaminants are usually Scheil distributed, which typically involves a relatively stable distribution in most part of the ingot, and a rapid increase in concentration close to the bottom. Metal contaminants may be introduced from the feedstock, and dopants (either n or p dopants) are added to the melt.Oxygen is dissolved from the crucible. The oxygen concentration typically decreases with increasing length, and is controlled by the rotation speed. This was confirmed by the interstitial oxygen measurements. The oxygen concentration showed no change after heat treatment, but the presence of oxygen in itself may contribute to produce lifetime reducing agents, such as precipitates and thermal donors. Thermal donors were found in the first 18cm of the ingot. Both the resistivity and lifetime measurements was used to calculate estimated lifetimes and donor concentrations, respectively. This estimated values were compared with the measured ones, revealing that the lifetime in the ingot was SRH dominated. Thermal donors were found to have less influence on the lifetime than the trapping. Oxygen precipitations may explain the low lifetime found in the center of the ingot up to about 30cm from the crown. Such precipitations are often gathered in defect bands in the sample. CDI of a Cu decorated sample revealed a pattern of different defect densities, which also showed up at the surface of the sample after preferential etching. An H- or L- band was believed to be situated here, which both consist of small oxygen precipitates. Defects arize as a funktion of the pulling parameters, and a low growth rate was connected to the low lifetime here. Indications of the presence of non-metallic traps were found throughout the ingot. However, oxygen precipitates could not explain the non-metallic traps that was found on the outside of the ingot, and the cause of these is therefore unknown. It is however likely that these traps may be connected to the pullrate/temperature gradient-ratio. Most likely metallic traps were also present. It is uncertain whether the non-metallic or metallic traps were the most important to the lifetime of this ingot, as the relative distribution of the two cannot be decided with certainty from the results in this thesis.Contrasts in CDI and steep curves using PCD measurements vs length plots were believed to be due to the lifetime degrading agent that changes the fastest. Metallic traps and the phosphorous dopant are known to be Scheil distributed, hence they appear transparent for the lifetime measurements in areas where the distribution is stable. Thermal donors and non-metallic traps are thus more likely to create contrast in the top parts of an ingot. However, it is not necessarily the phenomenon that causes the contrast that is the major lifetime degradation contributor.
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Liu, Ming. "Bridge network lifetime maintenance optimization under uncertainty." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3219201.
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Mousavifar, Seyed Ali. "Improving lifetime in wireless selective relay networks." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13400.
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Two novel algorithms based on imposing a soft limit on transmit power are proposed for improving the lifetimes of Amplify and Forward (AF) wireless relay networks. The impact of the algorithms on the network lifetime of four selective relay strategies, Minimum Transmission Power (MPT), Minimum Outage Probability (MOP), Maximum Energy Index (MEI), and Maximal Residual Energy (MRE) are studied. The network lifetime is defined as the number of successfully received messages at the destination while ensuring the system outage probability requirement is met.
In the first system model, there are N number of parallel relay paths with only one relay in each path between the source and the destination. The proposed algorithm uses the system outage probability derived in previous studies and a fixed transmit power threshold at the relays. The algorithm increases the lifetime drastically when the number of relays is larger than 3.
In the second system model, the destination uses N number of parallel paths with only one relay in each path and the source-destination link to receive messages. A diversity scheme is proposed in which the destination uses the source-destination link to obtain the signal broadcast to the relays by the source. The destination then informs the relays of the SNR deficiency which needs to be made up by the selected relay. The system outage probability is derived for the diversity scheme. The proposed algorithm deploys a dynamic transmit power threshold with the diversity scheme and improves the lifetime drastically.
The proposed algorithms are shown to improve the lifetime while ensuring that a target system outage probability is met. However, their features also increase the delay that a message may experience. To address this problem, we propose a delay reduction scheme, which disables the soft transmit power limit, if message delay exceeds a certain threshold. The delay reduction scheme is shown to significantly lower the message delay without much decrease in the lifetime.
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Kennett, Elizabeth Jane. "Lifetime and variability of atmospheric water vapour." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425367.
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Bosworth, Steven. "A measurement of the B-Baryon lifetime." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308501.
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Battu, Sivaram Kumar. "Data Acquisition System for Muon Lifetime Experiment." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_theses/230.
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I designed, developed and deployed a data acquisition (DAQ) system to meet the needsof the "??Lan" nuclear physics experiment. The main goal of the experiment is to measurethe positive muon lifetime to a precision of 1 part per million. This represents more thanan order of magnitude increase in precision beyond the current world average. The DAQdesign is motivated by very high data rate this experiment will produce. This experimentis being performed with the proton accelerator at Paul Scherrer Institut in Villigen,Switzerland. I have setup a mock experimental setup at the University of Kentucky. Thedesign and development of the DAQ software was conducted using this mock setup andwas deployed at Paul Scherrer Institut in the fall 2005.
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Wang, Yong-Zhi. "Stress corrosion crack coalescence and lifetime prediction." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315623.
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張秀霞 and Sau-ha Cheung. "Positron lifetime and mobility studies of SiC." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31220599.
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雷美琪 and Mei-ki Pattie Lui. "Positron lifetime study of Zn-doped GaSb." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226437.
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Booker, Ian Don. "Carrier Lifetime Relevant Deep Levels in SiC." Doctoral thesis, Linköpings universitet, Halvledarmaterial, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121515.
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Silicon carbide (SiC) is currently under development for high power bipolar devices such as insulated gate bipolar transistors (IGBTs). A major issue for these devices is the charge carrier lifetime, which, in the absence of structural defects such as dislocations, is influenced by point defects and their associated deep levels. These defects provide energy levels within the bandgap and may act as either recombination or trapping centers, depending on whether they interact with both conduction and valence band or only one of the two bands. Of all deep levels know in 4H-SiC, the intrinsic carbon vacancy related Z1/2 is the most problematic since it is a very effective recombination center which is unavoidably formed during growth. Its concentration in the epilayer can be decreased for the production of high voltage devices by injecting interstitial carbon, for example by oxidation, which, however, results in the formation of other new deep levels. Apart from intrinsic crystal flaws, extrinsic defects such as transition metals may also produce deep levels within the bandgap, which in literature have so far only been shown to produce trapping effects. The focus of the thesis is the transient electrical and optical characterization of deep levels in SiC and their influence on the carrier lifetime. For this purpose, deep level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS) variations were used in combination with time-resolved photoluminescence (TRPL). Paper 1 deals with a lifetime limiting deep level related to Fe-incorporation in n-type 4H-SiC during growth and papers 2 and 3 focus on identifying the main intrinsic recombination center in p-type 4H-SiC. In paper 4, the details of the charge carrier capture behavior of the deeper donor levels of the carbon vacancy, EH6/7, are investigated. Paper 5 deals with trapping effects created by unwanted incorporation of high amounts of boron during growth of n-type 4H-SiC which hinders the measurement of the carrier lifetime by room temperature TRPL. Finally, paper 6 is concerned with the characterization of oxidation-induced deep levels created in n- and p-type 4H- and 6H-SiC as a side-product of lifetime improvement by oxidation. In paper 1, the appearance of a new recombination center in n-type 4H-SiC, the RB1 level is discussed and the material is analyzed using room temperature TRPL, DLTS and pnjunction DLTS. The level appears to originate from a reactor contamination with Fe, a transition metal that generally leads to the formation of several trapping centers in the bandgap. Here it is found that under specific circumstances beneficial to the growth of high-quality material with a low Z1/2 concentration, the Fe incorporation also creates an additional recombination center capable of limiting the carrier lifetime. In paper 2, all deep levels found in p-type 4H-SiC grown at Linköping University which are accessible by DLTS and MCTS are investigated with regard to their efficiency as recombination centers. We find that none of the detectable levels is able to reduce carrier lifetime in p-type significantly, which points to the lifetime killer being located in the top half of the bandgap and having a large hole to electron capture cross section ratio (such as Z1/2, which is found in n-type material), making it undetectable by DLTS and MCTS. Paper 3 compares carrier lifetimes measured by temperature-dependent TRPL measurements in n- and p-type 4H-SiC and it is shown that the lifetime development over a large temperature range (77 - 1000 K) is similar in both types. This is interpreted as a further indication that the carbon vacancy related Z1/2 level is the main lifetime killer in p-type. In paper 4, the hole and electron capture cross sections of the near midgap deep levels EH6/7 are characterized. Both levels are capable of rapid electron capture but have only small hole capture rates, making them insignificant as recombination centers, despite their advantageous position near midgap. Minority carrier trapping by boron, which is both a p-type dopant and an unavoidable contaminant in 4H-SiC grown by CVD, is investigated in paper 5. Since even the shallow boron acceptor levels are relatively deep in the bandgap, minority trap and-release effects are detectable in room-temperature TRPL measurements. In case a high density of boron exists in n-type 4H-SiC, for example leached out from damaged graphite reactor parts during growth, we demonstrate that these trapping effects may be misinterpreted in room temperature TRPL measurements as a long free carrier lifetime. Paper 6 uses MCTS, DLTS, and room temperature TRPL to characterize the oxidation induced deep levels ON1 and ON2 in n- and p-type 4H- and their counterparts OS1-OS3 in 6H-SiC. The levels are found to all be positive-U, coupled two-levels defects which trap electrons efficiently but exhibit very inefficient hole capture once the defect is fully occupied by electrons. It is shown that these levels are incapable of significantly influencing carrier lifetime in epilayers which underwent high temperature lifetime enhancement oxidations. Due to their high density after oxidation and their high thermal stability they may, however, act to compensate n-type doping in low-doped material.
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Garrett, Simon Hornby. "Fluorescence lifetime measurements of sources in microcavities." Thesis, University of Exeter, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425324.
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Walmswell, Joseph James. "The late lifetime behaviour of massive stars." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708111.
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Rowley, Mark. "Bayesian analysis of fluorescence lifetime imaging data." Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/bayesian-analysis-of-fluorescence-lifetime-imaging-data(c2fc5ecd-517d-451c-a449-f07e566b3482).html.
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The development of a novel photon-by-photon Bayesian analysis for time-domain Fluorescence Lifetime Imaging Microscopy (FLIM) data, and its application to both real experimental biological and synthetic data, is presented in this thesis. FLIM is an intensity-independent and sensitive optical technique for studying the cellular envi- ronment and can robustly exploit Fo¨rster Resonance Energy Transfer (FRET) to enable protein-protein interactions to be located within living or fixed cells. Careful analysis of fluorescence lifetime data, often comprising multi-exponential kinetics, is crucial to elucidating FRET via FLIM. The developed Bayesian analysis is demonstrated to offer more accurate fitting of data with lower photon counts, allowing greater acquisition speeds. As well as revealing infor- mation previously unobtainable, such as direct error estimates, fitting model probabilities, and instrument response extraction, the developed approach allows for future extensions which can exploit the full probability distribution. In a section of this work already pub- lished [1], Bayesian mono-exponential analysis was shown to offer robust estimation with greater precision at low total photon counts, estimating fluorescent lifetimes to a level of accuracy not obtained using other techniques. Bayesian mono-exponential parameter es- timates obtained with the developed Bayesian analysis are improved compared to those obtained using maximum likelihood, least squares, and the phasor data fitting approaches. In this work, Bayesian bi-exponential analysis based on an improved fully-analytic time- domain FLIM system model is shown to also offer improved decay parameter estimates. The developed analysis offers fluorescence decay model selection by exploiting the hierarchical nature of Bayesian analysis. This innovation enables the quantitative determi- nation of the likelihood of the data being due to mono- or bi-exponential decay processes, for example. Model selection applied to FLIM promises to simplify processing where the exact kinetics are not known. Finally, the determination of an approximated instrument response function from observed fluorescence decay data alone is also possible.
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Lindholm, Henrik. "Floating Terminal: Technical Lifetime of 60 Years." Thesis, KTH, Lättkonstruktioner, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302786.
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Offshore solutions for container infrastructure such as Sea Technologies' floating container terminal can bring both environmental benefits and transport efficiencies for shipping.Large investment costs and requirements for long-term operational reliability for such structures entail the need for long technical service life. Several factors affect and limit the service life of marine structures, including fatigue and corrosion. The container terminal in question is in this context, marine structures, exceptionally large. This means that conventional maintenance of marine structures is not directly applicable and thus noticeable affect complexity of maintenance of the structure. In this work, factors that affect the technical service life and approaches to remedy these factors are investigated for marine structures in general and Sea Technologies' floating container terminal in particular. The purpose of the work has been to investigate possible approaches and technical solutions to meet a technical lifespan of 60 years. This has been done according to methodology from systems engineering with information and facts from studies of technical literature, industry publications and meetings and conversations with industry experts. The work has been limited to a literature study and conversations with experts within the time frames for a master's thesis. Areas affected by the work are corrosion, fatigue and underwater fouling. Lifelimiting factors have been identified in relation to its potential service life impact and maintenance complexity. Furthermore, requirements from stakeholders have been identified in accordance with the engineering of the system. Based on this, possible methods for meeting a life expectancy of 60 years have been investigated. The methods examined can be divided into three categories. These are, design measures, construction measures and maintenance measures. The possible measures examined have been compiled into a collection of recommended measures based on its technical functionality, estimated cost and fulfilment of stakeholder requirements. In summary, the report demonstrates that corrosion and corrosion protection are the most important factor in enabling long service life for this marine structure, both in terms of structural integrity and reliability of operations. Methods for corrosion protection and corrosion control recommended in the report are generally coating systems with extraordinarily long lifespans. Furthermore, a long technical life, also places demands for efficient and functional maintenance. The work therefore also presents recommendations on procedures for efficient maintenance, including the implementation of risk-based inspections and maintenance as well as technical solutions for systematisation and automation of inspections.Offshore lösningar för containerinfrastruktur såsom Sea Technologies flytande containerterminal kan medföra både miljövinster och transporteffektiviseringar för sjöfarten. Stora investeringskostnader och krav på lång operativ pålitlighet för sådana strukturer innebär behovet för lång teknisk livslängd. Flera faktorer påverkar och begränsar livslängden för marina konstruktioner, däribland utmattning och korrosion. Containerterminalen som avses är i sammanhanget marina konstruktioner, exceptionellt stor. Detta innebär att konventionellt underhåll av marina strukturer inte är direkt tillämpbart och därmed påtaglig komplexitet i underhåll av strukturen. I detta arbete utreds faktorer som påverkar teknisk livslängd tillvägagångssätt för avhjälpning av dessa faktorer för marina strukturer i allmänhet och Sea Technologies flytande containerterminal i synnerhet. Syftet med arbetet har varit att undersöka möjliga tillvägagångsätt och tekniska lösningar för att tillgodose en teknisk livslängd på 60 år. Detta har gjorts enligt metodik från systems engineering med information och fakta från studier av teknisk litteratur, branschpublikationer och moten och samtal med branschexperter. Arbetet har avgränsats till en litteraturstudie och samtal med experter inom tidsramarna för ett examensarbete på masternivå. Områden som berörs i arbetet är korrosion, utmattning och undervattensbeväxning. Livslängdsbegränsande har faktorer angivits i förhållande till dess potentiella livslängdspåverkan och underhållskomplexitet. Vidare har krav från intressenter identifierats i enlighet med sytems enginnering. Baserat på detta har därefter möjliga metoder för att tillgodose en livslängd på 60 år undersökts. Metoderna som undersöks kan delas in i tre kategorier. Dessa är, designåtgärder, konstruktionsåtgärder och underhållsåtgärder. De möjliga åtgärder som undersökts har sammanställts till en samling rekommenderade åtgärder baserat på dess tekniska funktionalitet, uppskattade kostnad och uppfyllande av intressenters krav. Sammanfattningsvis påvisas det i rapporten att korrosion och korrosionsskydd är den viktigaste faktorn för att möjliggöra lång livslängd både med avseende på strukturell integritet och pålitlighet i verksamhets drift. Metoder för korrosionsskydd och korrosionskontroll som rekommenderas i rapporten är generellt färgsystem med extraordinärt långa livslängder. Vidare ställer även lång teknisk livslängd, krav på effektivt och funktionellt underhåll. I presentationen presenteras därför även rekommendationer på tillvägagångssätt för effektivt underhåll, bland annat implementering av risk baserade inspektioner och underhåll samt tekniska lösningar för systematisering och automation av inspektioner.
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Jigang, M. "Defects and lifetime prediction of germanium MOSFETs." Thesis, Liverpool John Moores University, 2015. http://researchonline.ljmu.ac.uk/4587/.
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To continue improving device speed, much effort has been made to replace Si by high mobility semiconductors. Ge is considered as a strong candidate for pMOSFETs due to the high hole mobility. Two approaches have been demonstrated: high-k/Si-cap/Ge and high-k/GeO2/Ge. Negative Bias Temperature Instability (NBTI) is still one of the main reliability issues, limiting the device lifetime. In this project, it is found that the conventional lifetime prediction method developed for Si is inapplicable to Ge devicesand defect properties in Ge and Si MOSFETs are different. The threshold voltage degradation in Ge can be nearly 100% recovered under a much lower temperature than that in Si devices. The defect losses observed in Si devices were absent in Ge/GeO2/Al2O3. The generation of interface states is insignificant and the positive charges in GeO2/Al2O3 on Ge dominate the NBTI. These positive charges do not follow the same model as those in SiON/Si and an energy-alternating model has been proposed: there are a spread of energy levels of neutral hole traps below Ev andthey lift up after charging, and return below Ev after neutralization. The energy distribution of positive charges in the Al2O3/GeO2/Ge gate stack was studied by the Discharge-based Multi-pulse (DMP) Technique. The different stress-time dependence of defects below Ev and around Ec indicates that they originate from different defects. Quantization effect, Fermi level pinning, and discharge voltage step were considered. The defect differences in terms of the energy level were investigated by using the DMP technique and the energy alternating model is verified by the defect energy distribution. Based on the understanding of different defect behavior, a new NBTI lifetime prediction method was developed for Ge MOSFETs. Energy alternating defects were separated from as-grown hole traps (AHT), which enables to restore the power law for NBTI kinetics with a constant power exponent. The newly developed Ge method was applicable for NBTI lifetime prediction of the state-of-the-art Si-cap/Ge and GeO2/Ge MOSFETs. When compared with SiON/Si, the optimized Si-cap/Ge shows superior reliability, while GeO2/Ge is inferior and needs further optimization. Preliminary characterization was also carried out to investigate the impacts of energy levels and characteristic times of different defects on the frequency and duty factor dependence of AC NBTI degradation.
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Whitmore, Juliana. "A precision measurement of the Tau lifetime /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487841548268142.
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Demarest, Caitlin T. "Prolonging the Useful Lifetime of Artificial Lungs." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/870.
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Over 26 million Americans suffer from pulmonary disease, resulting in more than 150,000 deaths annually. Lung transplantation remains the only definitive treatment for many patients, but has meager survival rates and only approximately 1,700 of the 2,200 patients added to the lung transplant wait list each year are transplanted. Extracorporeal gas exchangers have been used as an alternative to mechanical ventilation in acute respiratory failure and as a bridge to transplantation in chronic respiratory failure. Current gas exchangers are limited by their high resistance and low biocompatibility that lead to patient complications and device clot formation. Therefore, there exists a dire need for improved devices that can act as destination therapy. To accomplish the goal of destination therapy, this dissertation discusses three studies that were performed to pave the way. First, I examined clot formation and failure patterns of two common clinical devices (Maquet’s CardioHelp (CH) and Quadrox (Qx)) to further our understanding of their limitations with respect to long-term support. Overall, it was demonstrated that the Qx devices fail earlier and more frequently than CH devices and result in a significantly greater reduction in platelet count, and that a four-inlet approach is beneficial. Next, I determined the optimal sweep gas nitric oxide (NO) concentration that minimizes platelet binding and activation while ensuring that blood methemoglobin (metHb) concentrations increase less than 5%. Miniature artificial lungs were attached to rabbits in a pumped veno-venous configuration and run for 4 h with NO added to the sweep gases in concentrations of 0, 100, 250, and 500 ppm (n=8 ea.). 100 ppm significantly reduced the amount of platelet consumption (p < 0.05), reduced platelet activation as measured by soluble p-selectin (p < 0.05), and had negligible increases in metHb and will thus be used in future experiments. Last, I tested the Pulmonary Assist Device (PAD) which was designed for long term use as a bridge to transplantation and destination therapy. Benchtop experiments were performed that confirmed that it meets our design and performance goals. From here, we are equipped to commence with 30-day PAD testing in sheep.
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Igba, Joel Ejiroghene. "Extending the lifetime of wind turbine gearboxes." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702308.
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Wind turbines (WTs) are a proven source of clean energy with wind power energy harvesting technologies supplying about 3% of global electricity consumption in 2014. However there is an increasing demand on maintenance and operational improvements since turbines have been plagued with downtime problems ofmajor components e.g. gearboxes, which in particular are known to have a higher downtime per failure than other WT subassemblies. This is as a result of two reasons. First, WT gearboxes have historically suffered from early failures due to the underestimation of operational load conditions. Second, WT gearboxes have very complex repair procedures needing heavy lifting equipment such as external cranes for repair and replacement. This downtime results in revenue loss for the customer. Hence, for a company like Vestas Wind Systems AlS, who designs, manufactures and services WTs dealing with the gearbox downtime issue is of great importance. This thesis focuses on the gearbox challenge specific to Vestas organisational context based on a research journey undertaken by the author whilst embedded in Vestas as an employee. It focuses on the 2MW fleet of gearboxes serviced by Vesias globally. Furthermore, the thesis addresses two dimensions of the industrial problem - (i) investigating the gearbox problem, i.e. the issue with reliability and maintainability, and identifying solutions for improving these, and (ii) improvement of Vestas internal processes which contribute to delivering maintenance and repair solutions for gearboxes e.g. the capturing and reusing of maintenance and repair data for failure and reliability analysis. These two strands of the research equip decision makers within Vestas with tools and techniques for making decisions concerning the maintenance and repair challenges. Hence, enabling the company to improve performance of the gearboxes and extending the life of gearboxes. The main outcomes of this thesis are the development of new and novel in-service decision-making models (and tools) which are currently adding 'value to Vestas. First, a preventive maintenance optimisation model was developed by applying state of the art approaches used in industries like aerospace and marine, to historical gearbox in-service data from Vestas operational WTs. This model estimates the optimal interval for preventive replacements, repair and inspections of gearboxes. The benefit to Vestas is that the model helps WT managers to make timely decisions regarding planning and scheduling maintenance, which can reduce the downtime considerably and avoid consequential failures, hence resulting in cost savings for the company. Second, a novel extreme vibration model was developed using the automated condition monitoring data from operational gearboxes. This model can help in detecting failures on the high speed and intermediate speed stages of the gearbox as early as one month in advance. The model was recently developed and validated and is soon to be implemented in the organisation but it is expected to help avoid consequential failures and reduce downtime due to the ability to plan and schedule maintenance early as soon as a fault is detected. Third, a decision support framework (with an accompanying tool) for repair cost estimation, gearbox damage classification and feedback of repair data to design, was developed using a soft systems approach. In addition, a data repository has been created which contains repair statistics that is used for analysis purposes for guiding repair decisions and of the design of new gearboxes. The developed models, framework and tools are now being used across the organisation by engineers and service personnel, and by Vestas external repair providers, which has led to savings for Vestas in the order of hundreds of thousands of Euros yearly.
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Cheung, Sau-ha. "Positron lifetime and mobility studies of SiC /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20357710.
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Lui, Mei-ki Pattie. "Positron lifetime study of Zn-doped GaSb /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B24534328.
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Fisher, Rebbeca. "Minority carrier lifetime mapping of solar cells." Thesis, Fisher, Rebbeca (2011) Minority carrier lifetime mapping of solar cells. Other thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/7603/.
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The minority carrier lifetime distribution across silicon solar cells was investigated using variations of the open circuit voltage decay method. This was performed on monocrystalline, polycrystalline and amorphous silicon solar cells. Light from a white LED was focused using an aperture and a glass bi-convex lens to a spot size of 2mm on the surface of each cell investigated and moved in 1mm increments. At each point, a short pulse of light was emitted from the LED, with the open circuit voltage generated measured with time. This decay was then analysed using two calculation methods using a program written in LabVIEW. The generated minority carrier lifetime values at each point were exported in an array and plotted in Microsoft Excel, so that maps of the minority carrier lifetime were created.
The calculation method from Mahan et al. (Mahan et al. 1979), produced values of the minority carrier lifetime that were consistently lower than the results found using the method from Ranjan, Solanki and Lal (Ranjan, Solanki, and Lal 2008). The values of the minority carrier lifetime obtained in both instances were generally in the expected range, once abnormally high lifetimes found to be a result of external factors (such as increased background effects due to low LED intensities or measured open circuit voltages) were removed.
Due to the high levels of inaccuracy involved in analysis of the open circuit voltage decay curves, it was determined that this method could not produce reliable values of the minority carrier lifetime. However, through agreement of the two calculation methods used, the distribution of the minority carrier lifetime (such as regions of comparatively high and low lifetimes across a cell) could be determined with some accuracy in the case of the monocrystalline and polycrystalline silicon cells.
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Beatton, Douglas Anthony. "The economics of happiness : a lifetime perspective." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/50009/1/Douglas_Beatton_Thesis.pdf.
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The three studies in this thesis focus on happiness and age and seek to contribute to our understanding of happiness change over the lifetime. The first study contributes by offering an explanation for what was evolving to a ‘stylised fact’ in the economics literature, the U-shape of happiness in age. No U-shape is evident if one makes a visual inspection of the age happiness relationship in the German socio-economic panel data, and, it seems counter-intuitive that we just have to wait until we get old to be happy. Eliminating the very young, the very old, and the first timers from the analysis did not explain away regression results supporting the U-shape of happiness in age, but fixed effect analysis did. Analysis revealed found that reverse causality arising from time-invariant individual traits explained the U-shape of happiness in age in the German population, and the results were robust across six econometric methods. Robustness was added to the German fixed effect finding by replicating it with the Australian and the British socio-economic panel data sets. During analysis of the German data an unexpected finding emerged, an exceedingly large negative linear effect of age on happiness in fixed-effect regressions. There is a large self-reported happiness decline by those who remain in the German panel. A similar decline over time was not evident in the Australian or the British data. After testing away age, time and cohort effects, a time-in-panel effect was found. Germans who remain in the panel for longer progressively report lower levels of happiness. Because time-in-panel effects have not been included in happiness regression specifications, our estimates may be biased; perhaps some economics of the happiness studies, that used German panel data, need revisiting. The second study builds upon the fixed-effect finding of the first study and extends our view of lifetime happiness to a cohort little visited by economists, children. Initial analysis extends our view of lifetime happiness beyond adulthood and revealed a happiness decline in adolescent (15 to 23 year-old) Australians that is twice the size of the happiness decline we see in older Australians (75 to 86 yearolds), who we expect to be unhappy due to declining income, failing health and the onset of death. To resolve a difference of opinion in the literature as to whether childhood happiness decreases, increases, or remains flat in age; survey instruments and an Internet-based survey were developed and used to collect data from four hundred 9 to 14 year-old Australian children. Applying the data to a Model of Childhood Happiness revealed that the natural environment life-satisfaction domain factor did not have a significant effect on childhood happiness. However, the children’s school environment and interactions with friends life-satisfaction domain factors explained over half a steep decline in childhood happiness that is three times larger than what we see in older Australians. Adding personality to the model revealed what we expect to see with adults, extraverted children are happier, but unexpectedly, so are conscientious children. With the steep decline in the happiness of young Australians revealed and explanations offered, the third study builds on the time-invariant individual trait finding from the first study by applying the Australian panel data to an Aggregate Model of Average Happiness over the lifetime. The model’s independent variable is the stress that arises from the interaction between personality and the life event shocks that affect individuals and peers throughout their lives. Interestingly, a graphic depiction of the stress in age relationship reveals an inverse U-shape; an inverse U-shape that looks like the opposite of the U-shape of happiness in age we saw in the first study. The stress arising from life event shocks is found to explain much of the change in average happiness over a lifetime. With the policy recommendations of economists potentially invoking unexpected changes in our lives, the ensuing stress and resulting (un)happiness warrant consideration before economists make policy recommendations.
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Sutcu, Sinan Mahmut. "The effects of ITO surface modification on lifetime in organic photovoltaic devices and a test setup for measuring lifetime." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34685.
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Though relatively young, the field of organic electronics is a rapidly growing market and considerable research is being done in creating a whole range of devices from organic molecules from organic field effect transistors to LEDs to photovoltaic devices. The field of organic photovoltaic in particular has become important in recent years with the push for newer, renewable sources of energy to end the dependence on fossil fuels. While the efficiencies of organic photovoltaic devices continue to rise, one barrier to their commercial adoption has been the limited lifetimes of these devices. While certain degradation methods of organic photovoltaics, such as photo-oxidation, have been extensively studied and solutions to these problems, such as encapsulation, are being researched, certain other degradation mechanisms are less understood and studied. The focus of this thesis is on one such degradation mechanism, UV degradation, specific to the ITO-pentacene interface in pentacene/C60 organic photovoltaic devices. Attempts were made to increase the lifetime of the devices by using phosphonic acids or oxygen plasma to modify the surface of the ITO. While conducting these experiments, the lack of a system to test the lifetime of multiple devices for long periods of time became apparent. As such as system was a requirement for future research into the lifetimes of organic photovoltaic devices a system was designed and built. The system would operate the photovoltaic device in a way comparable to its end-use and would allow over 100 devices to be tested simultaneously for durations exceeding 10,000 hours if necessary. This system would allow for statistically significant lifetime testing to be carried out in the future.