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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.
81

Implementation of Reliability Centered Asset Management method on Power Systems

Zhang, Yu January 2017 (has links)
Asset management is getting increasingly important in nearly all fields, especially inthe electric power engineering. It is mainly due to the following two reasons. First isthe high investment cost include the design cost, construction cost, equipment costand the high maintenance cost. Another reason is that there is always a high penaltyfee for the system operator if an interruption happened in the system. Besides, due tothe deregulation of electricity market in these years, the electricity utilities are payingmore attentions to the investment and maintenance cost. And one of their main goalsis to maximize the maintenance performance. So the challenge for the systems is toprovide high-reliability power to the customs and meanwhile be cost-effective for thesuppliers. Reliability Centered Asset Management (RCAM) is one of the bestmethods to solve this problem.The basic RCAM method is introduced first in this thesis. The model includes themaintenance strategy definition, the maintenance cost calculation and an optimizationmodel. Based on the basic model some improvements are added and a new model isproposed. The improvements include the new improvement maintenance strategy,increasing failure rate and a new objective function. The new model is also able toprovide a time-based maintenance plan.The simulation is done to a Swedish distribution system-Birka system by GAMS. Theresults and a sensitivity analysis is presented. A maintenance strategy for 58components and in 120 months is finally found. The impact on the changing failurerate is also shown for the whole peroid. / Kapitalförvaltning har inom alla områdem blivit allt viktigare, speciellt inomelkraftsteknik. Det beror i huvudsak av två orsaker. Den första är storinvesteringskostnad, vilket inkluderar design, konstruktion, utrustning och underhåll.Den andra är den höga straffavgiften för system operatören vid elavbrott. Dessutom,på grund av den nyligen avreglerade elmarknaden, så fäster elföretagen meruppmärksamhet på investerings och underhållskostnader. En av deras huvudmål är attmaximera underhållsprestandan. Så utmaningen för operatörerna är att levereratillförlitlig elkraft till kunder, samtidigt vara kostnadseffektiva mot leveratörer.Reliability Centered Asset Management (RCAM) är bland de bästa metoderna för attlösa detta problem. En enklare RCAM metod är introducerad först i denna rapport.Modellen inkluderar en underhållsstrategi-definition, underhållskostnad-kalkyl och enIIoptimiserings modell. Grundad på denna enklare modell, andra förbättringar ärtillagda och en ny modell är föreslagen. Förbättringarna inrymmer en nyunderhållsstrategi, ökad felfrekvens och en ny målfunktion. Den nya modellentillhandahåller också en tidsbaserad underhållsplan.
82

TRANSIENT-BASED RISK ANALYSIS OF WATER DISTRIBUTION SYSTEMS

Hoagland, Steven 01 January 2016 (has links)
Water distribution system utilities must be able to maintain a system’s assets (i.e., pumps, tanks, water mains, etc.) in good working condition in order to provide adequate water quantity and quality to its customers. Various asset management approaches are employed by utilities in order to make optimal decisions regarding the renewal of system components. Part of a good asset management approach is performing a comprehensive risk analysis which consists of considering all potential ways in which the system may fail, the likelihood failure of for each scenario, and the consequences of said failure. This study investigates a water distribution system’s risk of failure due to both acute transient events (e.g., pump trip) and standard pressure fluctuations due to daily system operations. Such an analysis may be useful in optimal decision making such as asset monitoring, scheduling of condition assessments or system renewal projects, policy implementation, and investment priorities in order to keep the utility’s total costs at a minimum. It may also be useful as a precautionary measure to help prevent catastrophic failures such as large main blowouts for which the utility would incur substantial costs, both direct and indirect. As part of this thesis, a database of water distribution system models is used to analyze the effects of an acute transient event for different system configurations. The database was created at the University of Kentucky and has been made available to the research community to test newly developed algorithms for various studies including optimal system operations and optimal system design.
83

Stratégie de maintenance centrée sur la fiabilité dans les réseaux électriques haute tension

Fouathia, Ouahab 22 September 2005 (has links)
Aujourd’hui les réseaux électriques sont exploités dans un marché dérégulé. Les gestionnaires des réseaux électriques sont tenus d’assurer un certain nombre de critères de fiabilité et de continuité du service, tout en minimisant le coût total consacré aux efforts effectués pour maintenir la fiabilité des installations. Il s’agit de trouver une stratégie, qui répond à plusieurs exigences, comme : le coût, les performances, la législation, les exigences du régulateur, etc. Cependant, le processus de prise de décision est subjectif, car chaque participant ramène sa contribution sur base de sa propre expérience. Bien que ce processus permette de trouver la « meilleure » stratégie, cette dernière n’est pas forcément la stratégie « optimale ». Ce compromis technico-économique a sensibilisé les gestionnaires des réseaux électriques à la nécessité d’un recours à des outils d’aide à la décision, qui doivent se baser sur des nouvelles approches quantitatives et une modélisation plus proches de la réalité physique. Cette thèse rentre dans le cadre d’un projet de recherche lancé par ELIA, et dénommé COMPRIMa (Cost-Optimization Models for the Planning of the Renewal, Inspection, and Maintenance of Belgian power system facilities). Ce projet vise à développer une méthodologie qui permet de modéliser une partie du réseau électrique de transport (par les réseaux de Petri stochastiques) et de simuler son comportement dynamique sur un horizon donné (simulation de Monte Carlo). L’évaluation des indices de fiabilité permet de comparer les différents scénarios qui tentent d’améliorer les performances de l’installation. L’approche proposée est basée sur la stratégie RCM (Reliability-Centered Maintenance). La méthodologie développée dans cette thèse permet une modélisation plus réaliste du réseau qui tient compte, entre autres, des aspects suivants : - La corrélation quantitative entre le processus de maintenance et le processus de vieillissement des composants (par un modèle d’âge virtuel) ; - Les dépendances liées à l’aspect multi-composant du système, qui tient compte des modes de défaillance spécifiques des systèmes de protection ; - L’aspect économique lié à la stratégie de maintenance (inspection, entretien, réparation, remplacement), aux coupures (programmées et forcées) et aux événements à risque (refus disjoncteur, perte d’un client, perte d’un jeu de barres, perte d’une sous-station, etc.).
84

Bundling Effects on Contract Performance of Highway Projects: Quantitative Analysis and Optimization Framework

Yu Qiao (6855683) 02 August 2019 (has links)
<div>The practice of project bundling, which involves combining multiple projects into a single multi-project contract, is in increased use at infrastructure agencies. Researchers have shown that this practice potentially reduces project cost but could cause undesirable consequences such as reduced market competition. For this reason, bundling policy needs to be guided by a determination of whether specific projects should be bundled, the bundling strategy in terms of bundle size, bundling combinations, geographical locations, and project scheduling, and the resulting outcome of each strategy in the terms of contract performance (overall cost and time duration, and cost and time overrun). Practitioners seeking answers to these questions continue to be stymied by the lack of quantified relationships between bundling alternatives and the resulting contract performance.</div><div>This dissertation addresses these questions by analyzing empirical data including the costs and durations of highway contracts and projects over a ten-year period. Using a variety of modeling approaches, the dissertation developed models to quantify the effects of bundling-related factors on the key contract performance measures (CPMs). The bundling related factors are contract size, bundle size, project combinations, project similarity and spatial proximity between bundled projects, and the CPMs are project cost and time performance, market competition, and the risks of cost overrun and project delay. Through the modeling process, the dissertation measured the effects of project similarity, economies of scale, economies of bundling, and economies of competition on bundling, and developed a novel technique to measure similarities between projects. Using the developed models, the dissertation then established an optimization framework to identify cost-effective bundling strategies. A greedy approach that minimizes the overall cost in a polynomial time was proposed to obtain heuristic solutions. The outcomes of this dissertation are twofold: first, it provides highway agencies with a quick, convenient and robust tool to design long-term cost-effective bundling strategies for any given pool of candidate projects; secondly, it provides guidelines and directions for future bundling policy formulation or evaluation. </div>
85

Criticality strategic decision making model for maintenance and asset management

Moghaddaszadeh Kermani, Mohammad January 2016 (has links)
Over the last century, there has been growing interest in changing the approach to maintenance management. The current practice for selecting critical equipment and making a decision on the most appropriate maintenance strategy is perceived to have serious limitations, principally because it lacks decision analysis. Due to the complex nature of decision-making in maintenance management, different models have been developed for selecting critical equipment. However, many of these models considered maintenance management as operational concern and ignored the strategic concerns of maintenance management. This thesis builds upon earlier works on decision-making for selecting critical equipment and maintenance strategy. It sets out to construct three hypotheses by introducing evidence from a comprehensive literature review, case study analysis and in-depth interviews. The thesis focuses on artificial intelligence and multi-criteria decision-making techniques (i.e. Fuzzy Logic and Analytical Hierarchy Process) to bridge this gap. It proposes a strategic decision-making model in maintenance and asset management for selecting critical equipment and deciding on a maintenance strategy. The novelty of model is to propose an approach in which maintenance strategy can be applied based on the equipment criticality while not making a trade-off between safety and cost but rather to combine the concern of safety with financial, operational and technical perspectives. The model provides an opportunity to consider safety as the first priority. The research output suggests that existing criticality assessment methods for optimising maintenance delivery have limited value and are suffering from a lack of strategic decision analysis. Multi-criteria decision-making tools could be used to improve decision-making of criticality assessment methods and hence maintenance strategy implementation. The validity of the proposed strategic decision-making model was tested through case study analysis and in-depth interviews. The results suggest that a strategic decision-making model could have a significant impact on improving safety, reliability and operational availability. The strategic decision-making model would enable asset managers to track the consequences of their decisions whilst dealing with maintenance. It is also an effective tool in the hands of a maintenance department to convince their asset managers to make a maintenance investment.
86

La gestion patrimoniale des objets de collection / The asset management of collectible items

Jouini, Mehdi-Emmanuel 30 November 2015 (has links)
Véritables actifs patrimoniaux, les objets de collection sont difficilement identifiables et qualifiables. Ne disposant pas d’une définition juridique classique, les objets de collection répondent d’une part, à une liste de biens issue des législations fiscales et d’autre part, aux différents critères énoncés par les instructions fiscales. Force est de constater que la gestion patrimoniale des objets de collection est actuellement écartée des schémas patrimoniaux. Toutefois, les possesseurs d’objets de collection sont régulièrement confrontés à des problématiques relatives à la transmission du patrimoine. Ainsi, il convient de s’interroger sur les différentes techniques patrimoniales qui permettent de réduire la pression fiscale relative à la transmission des objets de collection / Actual patrimonial assets, collectible items are hard to recognize and classify. Not possessing a conventional legal definition, collectible items meet on the one hand a list of assets coming from the tax legislation and on the other hand, the various criteria set by the tax instructions. It is clear that the asset management of collectible items is currently excluded from the patrimonial structures. However, owners of collectible items are regularly confronted with problems relating to the transfer of assets. Thus, it is appropriate to consider the various patrimonial techniques that allow one to reduce the tax burden on the transfer of collectible items
87

Integrated asset management systems for water infrastructure

Ward, Ben January 2015 (has links)
Owners of infrastructure assets have responsibility for the management of a diverse portfolio of civil engineering assets. These assets make up the foundations of modern society and are arguably pivotal in the economic growth and wellbeing of a nation. It is of no surprise therefore, that asset management business practises have risen in popularity as the UK’s infrastructure asset base continues to grow and inevitably ages with time. In the context of water and waste water infrastructure assets, which communities rely upon for health, economy and environmental sustainability, it is widely acknowledged that these assets have historically suffered from underinvestment. Whilst funding shortfalls have been evidenced historically, through the inadequacy of infrastructure to meet the needs and challenges of the past, it is of great concern that infrastructure expenditure is reducing in real terms as a result of the global financial crisis. This is leading to a widening funding gap between the available and the required finances for infrastructure investment which is further compounded by natural phenomena and human behaviours, i.e., climate change, population growth and urbanisation. To further intensify the problem, asset planning and management in the water industry is considered a complex and challenging discipline because of high interdependencies and the vast quantity of assets themselves. In acknowledgement of this global position, this thesis seeks to address some of the key challenges faced by utility companies in the adoption of asset management best practice across water and waste water assets, namely: • Operational decision making - the efficient and effective specification of least-cost rehabilitation programmes from condition information that ensure behavioural alignment with an organisations strategic objectives. • Tactical decision making - achieving risk based asset level inspection prioritisation that considers serviceability performance, for two particularly challenging asset groups: i.) High value - low volume assets and ii). Low value - high volume buried infrastructure. • Strategic decision making - identifying optimal long-term investment plans and asset management policies for assets that have previously not benefited from such technological advancements. To improve upon operational decision making, the author capitalises on the availability of condition inspection information for buried sewerage infrastructure by applying advanced optimisation techniques to help form an environment where the decision makers is presented with an array of optimal rehabilitation solutions. The trade-off curve that is presented uniquely evaluates solutions for the benefits they offer in-terms of: condition improvement, cost and operational performance. A financially favourable comparison (up to 45% saving) is drawn between the optimisation results which are automatically generated by the model and those that have been developed manually by experienced engineers in a ‘real world’ case study. However, it could be argued that the greatest benefit arises from the trade curve of feasible solutions which are presented to the decision maker across a range of investment levels. In recognition that tactical and strategic decision making have been the focus of a substantial amount of research for commonly found infrastructure assets, i.e., public sewers and water mains, a focus has been placed on improving upon and adopting best practise across infrastructure assets which have not previously benefited from the technological developments across these decision making levels. Firstly, a methodology for translating standardised condition inspection information into more meaningful reliability scores, to support risk based planning and decision making, is presented for service reservoirs. A service reservoir can be regarded as high value- low volume infrastructure asset and would typically have its condition evaluated between 1 (poor) to 5 (good). A case study demonstrates how this new reliability scoring mechanism has been successfully applied during a typical structural condition survey. The output from this process is a fully document reliability assessment for each component of the service reservoir. The output can be aggregated to provide an overall reliability assessment for the structure and/or used to target specific remedial works to troublesome components. Secondly, two methodologies are presented which address the fact that high volume – low value infrastructure assets across both the water distribution and wastewater collection networks, are typically less well understood and often sub-optimally managed in comparison to more critical or higher value assets. 1. A methodology has been developed to help UK water companies overcome the recent legislative changes associated with Section105A of the Water Act; which has transferred ownership of the private sewer network to UK water companies. The new methodology which has been developed, has allowed one of the UK’s water and sewerage companies to initiate a proactive asset management programme with the aim of addressing the deteriorating condition of these assets whilst also tackling their associated serviceability performance. Initially, a number of GIS tools are used to provide an estimate of the likely extent of the transferred network before a well-established public sewer deterioration model is used to predict the condition and operational performance of these S105A assets over time. 2. A novel deterioration modelling framework is developed by coupling the latest geospatial technologies with statistical deterioration modelling techniques. The modelling framework is specifically applied to small diameter water distribution assets (25-50mm diameter), known as communication pipes, which connect individual properties to the water distribution mains. Reliability curves are developed from failure data provided by two UK based Water Companies that have captured specific communication pipe failure records since 2001. The deterioration modelling curves and supporting data are compared and contrasted to demonstrate the robustness of this modelling approach, which is shown to be capable of modelling failure rates to a high degree of accuracy. This was validated by comparing the predicted number of failures against three years of failure data not used during the model building process. The yearly failure counts were predicted to within +/-5% accuracy and the overall cumulative modelled failure count at the end of 2014 was predicted within 1%. To conclude, the successful deterioration modelling tools for communication pipes are explored further, via the development of a strategic whole life cost optimisation framework for these assets. The outputs from the previous geospatial mapping tool are used alongside the calibrated Weibull deterioration curves to drive a whole life cost and performance analysis. Against this improved understanding of whole life costs, an optimisation algorithm is used to evaluate the trade-off between whole life costs (totex) and the prevention of future asset failures (serviceability). The model successfully identifies optimised investment policies according to the decision maker’s priorities which is evidenced in a case study that shows outperformance against existing maintenance policies for these assets. Financial savings in the region of £8.5M, or the prevention of 1,320 asset failures, were shown to be possible over a 25 years planning horizon in the case study. For the avoidance of confusion, the term ‘integrated’ is considered from the perspective of the three decision making levels associated with the management of an asset, namely: strategic, tactical and operational decision making. Therefore, data quality improvements and the management of information transactions between decisional levels are inherently considered within all of the methodologies developed in this thesis.
88

Index Tracking com controle do número de ativos e aplicação com uso de algoritmos genéticos

Sant'anna, Leonardo Riegel January 2014 (has links)
Nesta dissertação, discute-se o problema de otimização de carteiras de investimento para estratégia passiva de Index Tracking. Os objetivos principais são (i) apresentar um modelo de otimização de Index Tracking e (ii) a solucionar esse modelo com uso do método heurístico de Algoritmos Genéticos (AG) para formação de carteiras com número reduzido de ativos. O índice de referência utilizado é o Ibovespa, para o período de Janeiro/2009 a Julho/2012, com um total de 890 observações diárias de preços. A partir de uma amostra de 67 ativos, são formadas carteiras sem limite de ativos e limitadas a 40, 30, 20, 10 e 05 ativos; os intervalos de rebalanceamento das carteiras são 20, 40 e 60 períodos (dias úteis), ou seja, rebalanceamento mensal, bimestral e trimestral. É verificado que, para essa amostra, não é possível formar carteiras de 20 ou menos ativos via otimização direta com o solver Cplex com menos de 1 hora de processamento e gap abaixo de 5%. Com uso da heurística de Algoritmos Genéticos, são formadas carteiras de 10 e 05 ativos com tempo de processamento em torno de 5 minutos; nesse caso, o gap médio fica abaixo de 10% para ambos os tipos de carteira. E, com tempo de processamento do AG um pouco maior, em torno de 8 minutos, o algoritmo fornece soluções para carteiras de 10 e 05 ativos com gap médio abaixo de 5%. / In this master’s thesis it is discussed the portfolio optimization problem using the passive investment strategy of Index Tracking. The main goals are (i) to present an optimization model for the Index Tracking problem and (ii) to solve this model using the heuristic approach of Genetic Algorithms (GA) to create portfolios with reduced amount of stocks. The benchmark used is the Ibovespa Index (main reference for the Brazilian Stock Market), during the period from January/2009 to July/2012 (using a total of 890 daily stock prices). The sample contains 67 assets, and the model is used to build portfolios without limit in the amount of assets and portfolios limited to 40, 30, 20, 10 and 05 assets; the ranges of time to rebalance the portfolios are 20, 40, and 60 trading days, which means to rebalance monthly, bimonthly and quarterly. The results show that, considering this sample, it is not possible to build portfolios with 20 stocks (or less than 20) through direct optimization using the solver Cplex with computational processing time less than 1 hour and results with gap below 5%. On the other hand, using the Genetic Algorithms heuristic approach, portfolios limited to 10 and 05 stocks are built with computational time close to 5 minutes; for both types of portfolio, the solutions provided by the GA have average gap below 10%. Also, with a computational time slightly bigger, close to 8 minutes, the algorithm provides solutions with average gap below 5% for portfolios limited to 10 and 05 stocks.
89

Managing Geographic Data as an Asset: A Case Study in Large Scale Data Management

Smithers, Clay 21 November 2008 (has links)
Geographic data is a hallowed element within the Geographic Information Systems (GIS) discipline. As geographic data faces increased usage in distributed and mobile environments, the ability to access and maintain that data can become challenging. Traditional methods of data management through the use of file storage, databases, and data catalog software are valuable in their ability to organize data, but provide little information about how the data was collected, how often the data is updated, and what value the data holds for an organization. By defining geographic data as an asset it becomes a valuable resource that requires acquisition, maintenance and sometimes retirement during its lifetime. To further understand why geographic data is different than other types of data, we must look at the many components of geographic data and specifically how that data is gathered and organized. To best align geographic data to the asset management discipline, this thesis will focus on six key dimensions, established through the work of Vanier (2000, 2001), which seek to evaluate asset management systems. Using a conceptual narrative linked to an environmental analysis case study, this research seeks to inform as to the strategies for efficiently managing geospatial data resources. These resources gain value through the context applied by the inclusion of a standard structure and methodologies from the asset management field. The result of this thesis is the determination of the extent to which geographic data can be considered an asset, what asset management strategies are applicable to geographic data, and what are the requirements for geographic data asset management systems.
90

Fundos de investimento multimercados no Brasil: caracterização e fatores de retorno / Multimarket investment funds in Brazil: characterization and return factors

Schimidt, João Guilherme Araujo 13 February 2019 (has links)
O objetivo desse estudo foi analisar a origem dos retornos dos fundos de investimentos multimercados brasileiros. Baseado em uma conjuntura econômica de perspectivas futuras, dado queda sistêmica da taxa de juros nos últimos anos, com reformas estruturais - na área trabalhista e previdenciária - de movimentação dos capitais alocados nos fundos de renda fixa para os fundos de investimentos multimercados foi definido o universo dos fundos multimercados brasileiros como o objeto de estudo da presente dissertação. Com base em dados iniciais que envolviam o período de janeiro de 1996 e setembro de 2018, caracterizou-se a indústria de fundos multimercados de forma ampla. Após a análise geral dos fundos e, mais especificamente, dos fundos multimercados, tomou-se como base fundos que estiveram ativos entre 01/01/2008 e 31/08/2018, com o intuito de avaliar o desempenho em um período de amplas mudanças na economia brasileira. Os ganhos desses fundos foram relacionados, através de regressão linear, com índice IBOVESPA, índice IMA-B, taxa SELIC, índice S&P 500 e taxa de cambio R$/US$, representado pela taxa PTAX do Banco Central do Brasil. Os resultados obtidos demonstram que a indústria de fundos multimercados e caracterizada por poucas gestoras no mercado, caudas longas nos patrimônios dos fundos, efeito smartmoney e alta mortalidade dos fundos. Ha indícios de relação positiva entre o patrimônio do fundo e seu desempenho. A maioria dos fundos gera taxas de retorno efetiva anual positiva, especialmente os mais antigos, porém, o ganho acima do CDI está limitado a um número menor de fundos, sem associação com a longevidade do fundo. Os principais mercados de origem dos retorno dos fundos e o acionário nacional (IBOVESPA) e o renda fixa de títulos públicos atrelados a inflação (IMA-B). Ha uma relação positiva entre o número de variáveis explicativas significativas e o desempenho dos fundos multimercados. Fundos que conseguem extrair retornos de um maior número de mercados apresentam desenho superior. Em síntese fundos que melhor analisam o mercado nacional, tanto acionário quanto o de renda fixa, tendem a superar seus pares ao gerar ganhos superiores para o investidor. / The objective of this study was to analyze the origin of the returns of Brazilian multimarket investment funds. Based on an economic outlook for the future, a systemic fall in interest rates in recent years, with structural reforms - in the labor and social security area - to move funds allocated to fixed income funds to multi-market investment funds was defined as the object of study of the present dissertation. Based on initial data that covered the period of January 1996 and September 2018, the multimarket funds industry was characterized in a broad way. After the general analysis of the funds and, more specifically, of the multimarket funds, funds were used that were active between 01/01/2008 and 08/31/2018, in order to evaluate the performance in a period of extensive changes in the Brazilian economy. The gains from these funds were related to the IBOVESPA index, the IMA-B index, the SELIC rate, the S&P 500 index and the R$/US $ exchange rate, represented by the PTAX rate of the Central Bank of Brazil. The results show that the multimarket funds industry is characterized by few managers in the market, long tails in the fund assets, smartmoney effect and high fund mortality. There is evidence of a positive relationship between the fund\'s assets and its performance. Most funds generate positive annual effective return rates, especially the older ones, however, the gain above the CDI is limited to a smaller number of funds, with no association with the longevity of the fund. The main markets for return of funds are the national stock (IBOVESPA) and the fixed income of inflation-linked government bonds (IMA-B). There is a positive relationship between the number of significant explanatory variables and the performance of multimarket funds. Funds that manage to extract returns from a greater number of markets present superior design. In summary, funds that better analyze the domestic market, both shareholder and fixed income, tend to outperform their peers by generating superior gains for the investor.

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