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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.
41

Utility optimal decision making when responding to No Fault Found events

Archana Ravindran (9029510) 26 June 2020 (has links)
<p>No Fault Founds (NFFs) are an expensive problem faced by the airline industry. The underlying cause of NFFs are a major focus of research work in the field, but the dearth of consistent data is a roadblock faced by many decision makers. An important risk factor identified is the occurrence rate of NFFs.</p><p>This research work aims to help decision makers in the Airline Maintenance, Repair and Overhaul teams, when faced with recurring NFFs, to make a choice based on value derived from the system and risk preference of the decision maker under uncertainty. The value of the aircraft fleet is laid out using Net Present Value at every decision point along the system life cycle while accounting for the uncertainty in the failure rate information. Two extreme decisions are considered for the decision maker to choose between: rebooting the system every time a failure occurs and results in an NFF which allows for it to recur while reducing uncertainty of the failure rate; or eliminating the failure mode which assumes that the failure does not recur and therefore completely removes the uncertainty. Both decisions have their associated uncertain costs that affect the NPV calculated. We use a Monte Carlo approach to estimate the expected profit from deciding to eliminate the failure mode. We make use of Expected Utility Theory to account for the risk preference of a decision maker under uncertainty and build an Expected Utility Maximizing decision framework.</p>To conclude we give some guidance to interpret the results and understand what factors influence the optimal decision. We conclude that not accounting for uncertainty in estimating a failure rate for the future along with uncertainty in NFF costs can lead to an undesirable decision. If the decision maker waits too long to gather more information and reduce uncertainty, then rebooting the system for the remaining life could be more worthwhile than spending the large amount of money to Eliminate a failure mode. Finally, we conclude that, despite uncertainties in information of occurrence rates and costs of NFFs, an Expected Utility maximizing decision between the two options considered – Reboot and Eliminate – is possible given the available information.
42

A Customer Value Assessment Process (CVAP) for Ballistic Missile Defense

Hernandez, Alex 01 June 2015 (has links) (PDF)
A systematic customer value assessment process (CVAP) was developed to give system engineering teams the capability to qualitatively and quantitatively assess customer values. It also provides processes and techniques used to create and identify alternatives, evaluate alternatives in terms of effectiveness, cost, and risk. The ultimate goal is to provide customers (or decision makers) with objective and traceable procurement recommendations. The creation of CVAP was driven by an industry need to provide ballistic missile defense (BMD) customers with a value proposition of contractors’ BMD systems. The information that outputs from CVAP can be used to guide BMD contractors in formulating a value proposition, which is used to steer customers to procure their BMD system(s) instead of competing system(s). The outputs from CVAP also illuminate areas where systems can be improved to stay relevant with customer values by identifying capability gaps. CVAP incorporates proven approaches and techniques appropriate for military applications. However, CVAP is adaptable and may be applied to business, engineering, and even personal every-day decision problems and opportunities. CVAP is based on the systems decision process (SDP) developed by Gregory S. Parnell and other systems engineering faculty at the Unites States Military Academy (USMA). SDP combines Value-Focused Thinking (VFT) decision analysis philosophy with Multi-Objective Decision Analysis (MODA) quantitative analysis of alternatives. CVAP improves SDP’s qualitative value model by implementing Quality Function Deployment (QFD), solution design implements creative problem solving techniques, and the qualitative value model by adding cost analysis and risk assessment processes practiced by the U.S DoD and industry. CVAP and SDP fundamentally differ from other decision making approaches, like the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), by distinctly separating the value/utility function assessment process with the ranking of alternatives. This explicit value assessment allows for straightforward traceability of the specific factors that influence decisions, which illuminates the tradeoffs involved in making decisions with multiple objectives. CVAP is intended to be a decision support tool with the ultimate purpose of helping decision makers attain the best solution and understanding the differences between the alternatives. CVAP does not include any processes for implementation of the alternative that the customer selects. CVAP is applied to ballistic missile defense (BMD) to give contractors ideas on how to use it. An introduction of BMD, unique BMD challenges, and how CVAP can improve the BMD decision making process is presented. Each phase of CVAP is applied to the BMD decision environment. CVAP is applied to a fictitious BMD example.
43

Multialternative Decision Field Theory Model Fitting Using Different Measures of Attribute Weighting

Zhang, Ruohui 14 July 2015 (has links)
No description available.
44

Stochastic modeling and methods for portfolio management in cointegrated markets

Angoshtari, Bahman January 2014 (has links)
In this thesis we study the utility maximization problem for assets whose prices are cointegrated, which arises from the investment practice of convergence trading and its special forms, pairs trading and spread trading. The major theme in the first two chapters of the thesis, is to investigate the assumption of market-neutrality of the optimal convergence trading strategies, which is a ubiquitous assumption taken by practitioners and academics alike. This assumption lacks a theoretical justification and, to the best of our knowledge, the only relevant study is Liu and Timmermann (2013) which implies that the optimal convergence strategies are, in general, not market-neutral. We start by considering a minimalistic pairs-trading scenario with two cointegrated stocks and solve the Merton investment problem with power and logarithmic utilities. We pay special attention to when/if the stochastic control problem is well-posed, which is overlooked in the study done by Liu and Timmermann (2013). In particular, we show that the problem is ill-posed if and only if the agent’s risk-aversion is less than a constant which is an explicit function of the market parameters. This condition, in turn, yields the necessary and sufficient condition for well-posedness of the Merton problem for all possible values of agent’s risk-aversion. The resulting well-posedness condition is surprisingly strict and, in particular, is equivalent to assuming the optimal investment strategy in the stocks to be market-neutral. Furthermore, it is shown that the well-posedness condition is equivalent to applying Novikov’s condition to the market-price of risk, which is a ubiquitous sufficient condition for imposing absence of arbitrage. To the best of our knowledge, these are the only theoretical results for supporting the assumption of market-neutrality of convergence trading strategies. We then generalise the results to the more realistic setting of multiple cointegrated assets, assuming risk factors that effects the asset returns, and general utility functions for investor’s preference. In the process of generalising the bivariate results, we also obtained some well-posedness conditions for matrix Riccati differential equations which are, to the best of our knowledge, new. In the last chapter, we set up and justify a Merton problem that is related to spread-trading with two futures assets and assuming proportional transaction costs. The model possesses three characteristics whose combination makes it different from the existing literature on proportional transaction costs: 1) finite time horizon, 2) Multiple risky assets 3) stochastic opportunity set. We introduce the HJB equation and provide rigorous arguments showing that the corresponding value function is the viscosity solution of the HJB equation. We end the chapter by devising a numerical scheme, based on the penalty method of Forsyth and Vetzal (2002), to approximate the viscosity solution of the HJB equation.
45

L’effet des lois sur l’évasion fiscale : une synthèse systématique des recherches évaluatives

Blanchette, Maude 08 1900 (has links)
Contexte et objectif. L’évasion fiscale a généré des pertes annuelles variant entre 2 et 44 milliards au Canada entre 1976 et 1995. Avec la croissance de l’évasion fiscale dans les années 1980 et 1990 plusieurs législations se sont attaquées à ce phénomène en mettant en place des mesures telles que les amnisties, les réformes fiscales et les nouvelles lois. Ces dernières reposent non seulement sur des principes théoriques distincts, mais leur efficacité même est remise en question. Bien que plusieurs auteurs affirment que les criminels en col blanc sont réceptifs aux sanctions pénales, une telle affirmation repose sur peu de preuves empiriques. L’objectif de ce mémoire est donc de réaliser une synthèse systématique des études évaluatives afin de faire un bilan des lois fiscales et d’évaluer leurs effets sur la fraude fiscale. Méthodologie. La synthèse systématique est la méthodologie considérée comme la plus rigoureuse pour se prononcer sur l’effet produit par une population relativement homogène d’études. Ainsi, 18 bases de données ont été consultées et huit études ont été retenues sur les 23 723 références. Ces huit études contiennent neuf évaluations qui ont estimé les retombés des lois sur 17 indicateurs de fraude fiscale. L’ensemble des études ont été codifiées en fonction du type de loi et leur rigueur méthodologique. La méthode du vote-count fut employée pour se prononcer sur l’efficacité des lois. Résultats. Sur les 17 indicateurs, sept indiquent que les lois n’ont eu aucun effet sur l’évasion fiscale tandis que six témoignent d’effets pervers. Seulement quatre résultats sont favorables aux lois, ce qui laisse présager que ces dernières sont peu efficaces. Toutefois, en scindant les résultats en fonction du type de loi, les réformes fiscales apparaissent comme une mesure efficace contrairement aux lois et amnisties. Conclusion. Les résultats démontrent que les mesures basées sur le modèle économique de Becker et qui rendent le système plus équitable sont prometteuses. Les amnisties qui visent à aller chercher des fraudeurs en leur offrant des avantages économiques et en suspendant les peines sont non seulement inefficaces, mais menaceraient le principe d’autocotisation basé sur l’équité. / Introduction and objectives. Between 1976 and 1995, tax evasion has generated losses varying between 2 to 44 billions in Canada. In order to stop the upward trend observed in tax evasion in the 1980s and 1990s, several jurisdictions introduced legal measures such as amnesties, tax reforms and new legislations. Not only these measures rest on different paradigms but their effectiveness has yet to be proven. While it is generally argued that threats of legal sanctions are effective to deal with offenders involved in economic crimes, such a claim rests on weak empirical evidence. By conducting a systematic review, the objective of this thesis is to further our understanding about the effect of tax laws on tax evasion. Method. Systematic review is referred to as the most suitable method to review a body of literature on a given subject and to determine its effect on a particular outcome. We searched 18 databases that led to the identification of 23,723 references. Overall, 8 studies containing 9 evaluations met inclusion criteria and were kept for the review. These studies assess the effect of tax laws on a total of 17 variables. All studies were assessed based on the type of law and their methodological robustness. The vote-count method was then used to identify effective measures. Results. Out of the 17 outcomes, 7 indicate that laws have no effect on tax evasion while 6 show increases in tax evasion indicators. Only 4 outcomes were in the expected direction. On the other hand, by grouping results according to the type of measures, tax reform appears as the only effective intervention. Conclusion. Our results suggest that programs based on Becker’s economic model and that promote equity are promising. Amnesties seeking to identify tax evaders by offering economic advantages and sanction immunity are not only ineffective but could compromise a system based on self-assessment, which rest on the principle of perceived equity.
46

Extração de preferências por meio de avaliações de comportamentos observados. / Preference elicitation using evaluation over observed behaviours.

Silva, Valdinei Freire da 07 April 2009 (has links)
Recentemente, várias tarefas tem sido delegadas a sistemas computacionais, principalmente quando sistemas computacionais são mais confiáveis ou quando as tarefas não são adequadas para seres humanos. O uso de extração de preferências ajuda a realizar a delegação, permitindo que mesmo pessoas leigas possam programar facilmente um sistema computacional com suas preferências. As preferências de uma pessoa são obtidas por meio de respostas para questões específicas, que são formuladas pelo próprio sistema computacional. A pessoa age como um usuário do sistema computacional, enquanto este é visto como um agente que age no lugar da pessoa. A estrutura e contexto das questões são apontadas como fonte de variações das respostas do usuário, e tais variações podem impossibilitar a factibilidade da extração de preferências. Uma forma de evitar tais variações é questionar um usuário sobre a sua preferência entre dois comportamentos observados por ele. A questão de avaliar relativamente comportamentos observados é mais simples e transparente ao usuário, diminuindo as possíveis variações, mas pode não ser fácil para o agente interpretar tais avaliações. Se existem divergências entre as percepções do agente e do usuário, o agente pode ficar impossibilitado de aprender as preferências do usuário. As avaliações são geradas com base nas percepções do usuário, mas tudo que um agente pode fazer é relacionar tais avaliações às suas próprias percepções. Um outro problema é que questões, que são expostas ao usuário por meio de comportamentos demonstrados, são agora restritas pela dinâmica do ambiente e um comportamento não pode ser escolhido arbitrariamente. O comportamento deve ser factível e uma política de ação deve ser executada no ambiente para que um comportamento seja demonstrado. Enquanto o primeiro problema influencia a inferência de como o usuário avalia comportamentos, o segundo problema influencia quão rápido e acurado o processo de aprendizado pode ser feito. Esta tese propõe o problema de Extração de Preferências com base em Comportamentos Observados utilizando o arcabouço de Processos Markovianos de Decisão, desenvolvendo propriedades teóricas em tal arcabouço que viabilizam computacionalmente tal problema. O problema de diferentes percepções é analisado e soluções restritas são desenvolvidas. O problema de demonstração de comportamentos é analisado utilizando formulação de questões com base em políticas estacionárias e replanejamento de políticas, sendo implementados algoritmos com ambas soluções para resolver a extração de preferências em um cenário sob condições restritas. / Recently, computer systems have been delegated to accomplish a variety of tasks, when the computer system can be more reliable or when the task is not suitable or not recommended for a human being. The use of preference elicitation in computational systems helps to improve such delegation, enabling lay people to program easily a computer system with their own preference. The preference of a person is elicited through his answers to specific questions, that the computer system formulates by itself. The person acts as an user of the computer system, whereas the computer system can be seen as an agent that acts in place of the person. The structure and context of the questions have been pointed as sources of variance regarding the users answers, and such variance can jeopardize the feasibility of preference elicitation. An attempt to avoid such variance is asking an user to choose between two behaviours that were observed by himself. Evaluating relatively observed behaviours turn questions more transparent and simpler for the user, decreasing the variance effect, but it might not be easier interpreting such evaluations. If divergences between agents and users perceptions occur, the agent may not be able to learn the users preference. Evaluations are generated regarding users perception, but all an agent can do is to relate such evaluation to his own perception. Another issue is that questions, which are exposed to the user through behaviours, are now constrained by the environment dynamics and a behaviour cannot be chosen arbitrarily, but the behaviour must be feasible and a policy must be executed in order to achieve a behaviour. Whereas the first issue influences the inference regarding users evaluation, the second problem influences how fast and accurate the learning process can be made. This thesis proposes the problem of Preference Elicitation under Evaluations over Observed Behaviours using the Markov Decision Process framework and theoretic properties in such framework are developed in order to turn such problem computationally feasible. The problem o different perceptions is analysed and constraint solutions are developed. The problem of demonstrating a behaviour is considered under the formulation of question based on stationary policies and non-stationary policies. Both type of questions was implemented and tested to solve the preference elicitation in a scenario with constraint conditions.
47

Extração de preferências por meio de avaliações de comportamentos observados. / Preference elicitation using evaluation over observed behaviours.

Valdinei Freire da Silva 07 April 2009 (has links)
Recentemente, várias tarefas tem sido delegadas a sistemas computacionais, principalmente quando sistemas computacionais são mais confiáveis ou quando as tarefas não são adequadas para seres humanos. O uso de extração de preferências ajuda a realizar a delegação, permitindo que mesmo pessoas leigas possam programar facilmente um sistema computacional com suas preferências. As preferências de uma pessoa são obtidas por meio de respostas para questões específicas, que são formuladas pelo próprio sistema computacional. A pessoa age como um usuário do sistema computacional, enquanto este é visto como um agente que age no lugar da pessoa. A estrutura e contexto das questões são apontadas como fonte de variações das respostas do usuário, e tais variações podem impossibilitar a factibilidade da extração de preferências. Uma forma de evitar tais variações é questionar um usuário sobre a sua preferência entre dois comportamentos observados por ele. A questão de avaliar relativamente comportamentos observados é mais simples e transparente ao usuário, diminuindo as possíveis variações, mas pode não ser fácil para o agente interpretar tais avaliações. Se existem divergências entre as percepções do agente e do usuário, o agente pode ficar impossibilitado de aprender as preferências do usuário. As avaliações são geradas com base nas percepções do usuário, mas tudo que um agente pode fazer é relacionar tais avaliações às suas próprias percepções. Um outro problema é que questões, que são expostas ao usuário por meio de comportamentos demonstrados, são agora restritas pela dinâmica do ambiente e um comportamento não pode ser escolhido arbitrariamente. O comportamento deve ser factível e uma política de ação deve ser executada no ambiente para que um comportamento seja demonstrado. Enquanto o primeiro problema influencia a inferência de como o usuário avalia comportamentos, o segundo problema influencia quão rápido e acurado o processo de aprendizado pode ser feito. Esta tese propõe o problema de Extração de Preferências com base em Comportamentos Observados utilizando o arcabouço de Processos Markovianos de Decisão, desenvolvendo propriedades teóricas em tal arcabouço que viabilizam computacionalmente tal problema. O problema de diferentes percepções é analisado e soluções restritas são desenvolvidas. O problema de demonstração de comportamentos é analisado utilizando formulação de questões com base em políticas estacionárias e replanejamento de políticas, sendo implementados algoritmos com ambas soluções para resolver a extração de preferências em um cenário sob condições restritas. / Recently, computer systems have been delegated to accomplish a variety of tasks, when the computer system can be more reliable or when the task is not suitable or not recommended for a human being. The use of preference elicitation in computational systems helps to improve such delegation, enabling lay people to program easily a computer system with their own preference. The preference of a person is elicited through his answers to specific questions, that the computer system formulates by itself. The person acts as an user of the computer system, whereas the computer system can be seen as an agent that acts in place of the person. The structure and context of the questions have been pointed as sources of variance regarding the users answers, and such variance can jeopardize the feasibility of preference elicitation. An attempt to avoid such variance is asking an user to choose between two behaviours that were observed by himself. Evaluating relatively observed behaviours turn questions more transparent and simpler for the user, decreasing the variance effect, but it might not be easier interpreting such evaluations. If divergences between agents and users perceptions occur, the agent may not be able to learn the users preference. Evaluations are generated regarding users perception, but all an agent can do is to relate such evaluation to his own perception. Another issue is that questions, which are exposed to the user through behaviours, are now constrained by the environment dynamics and a behaviour cannot be chosen arbitrarily, but the behaviour must be feasible and a policy must be executed in order to achieve a behaviour. Whereas the first issue influences the inference regarding users evaluation, the second problem influences how fast and accurate the learning process can be made. This thesis proposes the problem of Preference Elicitation under Evaluations over Observed Behaviours using the Markov Decision Process framework and theoretic properties in such framework are developed in order to turn such problem computationally feasible. The problem o different perceptions is analysed and constraint solutions are developed. The problem of demonstrating a behaviour is considered under the formulation of question based on stationary policies and non-stationary policies. Both type of questions was implemented and tested to solve the preference elicitation in a scenario with constraint conditions.
48

L’effet des lois sur l’évasion fiscale : une synthèse systématique des recherches évaluatives

Blanchette, Maude 08 1900 (has links)
Contexte et objectif. L’évasion fiscale a généré des pertes annuelles variant entre 2 et 44 milliards au Canada entre 1976 et 1995. Avec la croissance de l’évasion fiscale dans les années 1980 et 1990 plusieurs législations se sont attaquées à ce phénomène en mettant en place des mesures telles que les amnisties, les réformes fiscales et les nouvelles lois. Ces dernières reposent non seulement sur des principes théoriques distincts, mais leur efficacité même est remise en question. Bien que plusieurs auteurs affirment que les criminels en col blanc sont réceptifs aux sanctions pénales, une telle affirmation repose sur peu de preuves empiriques. L’objectif de ce mémoire est donc de réaliser une synthèse systématique des études évaluatives afin de faire un bilan des lois fiscales et d’évaluer leurs effets sur la fraude fiscale. Méthodologie. La synthèse systématique est la méthodologie considérée comme la plus rigoureuse pour se prononcer sur l’effet produit par une population relativement homogène d’études. Ainsi, 18 bases de données ont été consultées et huit études ont été retenues sur les 23 723 références. Ces huit études contiennent neuf évaluations qui ont estimé les retombés des lois sur 17 indicateurs de fraude fiscale. L’ensemble des études ont été codifiées en fonction du type de loi et leur rigueur méthodologique. La méthode du vote-count fut employée pour se prononcer sur l’efficacité des lois. Résultats. Sur les 17 indicateurs, sept indiquent que les lois n’ont eu aucun effet sur l’évasion fiscale tandis que six témoignent d’effets pervers. Seulement quatre résultats sont favorables aux lois, ce qui laisse présager que ces dernières sont peu efficaces. Toutefois, en scindant les résultats en fonction du type de loi, les réformes fiscales apparaissent comme une mesure efficace contrairement aux lois et amnisties. Conclusion. Les résultats démontrent que les mesures basées sur le modèle économique de Becker et qui rendent le système plus équitable sont prometteuses. Les amnisties qui visent à aller chercher des fraudeurs en leur offrant des avantages économiques et en suspendant les peines sont non seulement inefficaces, mais menaceraient le principe d’autocotisation basé sur l’équité. / Introduction and objectives. Between 1976 and 1995, tax evasion has generated losses varying between 2 to 44 billions in Canada. In order to stop the upward trend observed in tax evasion in the 1980s and 1990s, several jurisdictions introduced legal measures such as amnesties, tax reforms and new legislations. Not only these measures rest on different paradigms but their effectiveness has yet to be proven. While it is generally argued that threats of legal sanctions are effective to deal with offenders involved in economic crimes, such a claim rests on weak empirical evidence. By conducting a systematic review, the objective of this thesis is to further our understanding about the effect of tax laws on tax evasion. Method. Systematic review is referred to as the most suitable method to review a body of literature on a given subject and to determine its effect on a particular outcome. We searched 18 databases that led to the identification of 23,723 references. Overall, 8 studies containing 9 evaluations met inclusion criteria and were kept for the review. These studies assess the effect of tax laws on a total of 17 variables. All studies were assessed based on the type of law and their methodological robustness. The vote-count method was then used to identify effective measures. Results. Out of the 17 outcomes, 7 indicate that laws have no effect on tax evasion while 6 show increases in tax evasion indicators. Only 4 outcomes were in the expected direction. On the other hand, by grouping results according to the type of measures, tax reform appears as the only effective intervention. Conclusion. Our results suggest that programs based on Becker’s economic model and that promote equity are promising. Amnesties seeking to identify tax evaders by offering economic advantages and sanction immunity are not only ineffective but could compromise a system based on self-assessment, which rest on the principle of perceived equity.
49

David Gauthier’s Moral Contractarianism and the Problem of Secession

Etieyibo, Edwin Unknown Date
No description available.
50

David Gauthiers Moral Contractarianism and the Problem of Secession

Etieyibo, Edwin 11 1900 (has links)
This thesis proposes a reading of David Gauthiers moral contractarianism (hereinafter Mb(CM)A) that demonstrates how cooperation can be rational in situations where expected utilities (EU) are stacked too high against cooperation. The dissertation critically examines Mb(CM)A and contends that it breaks down in the test of application, i.e. the problem of secession because of the conception of rationality it appeals to. Mb(CM)A identifies rationality with utility-maximization, where utility is the measure of considered coherent preferences about outcomes. Mb(CM)A links morality to reason, and reason to practical rationality, and practical rationality to interest, which it identifies with individual utility. On this view, an action (or a disposition) is rational if that action (or disposition) maximizes an agents EU. This conception of rationality the essay claims is both nave and misleading because it does not take into account an agents considered preference for the acts that are available, in addition to the EU of those acts. Therefore, the thesis argues that Mb(CM)As account of rationality be abandoned in favor of a decision-value/symbolic utilitys or morals by decision-value agreements conception of practical rationality. Morals by decision-value agreement (henceforth Mb(DV)A), the dissertation claims, handles serious problems, like the problem of secession in ways that Mb(CM)A cannot. Mb(CM)A breaks down in the test of application because when applied to the problem of secession, it suggests a single-tracked silver bullet solution. Specifically, it tracks only EU-reasons and claims that insofar as cooperation does not maximize the EU of better-off agents, it is not rational for them to cooperate with or support those that are less well-off. By contrast, Mb(DV)A offers a multi-tracked framework for solutions to the problem, namely: it factors in an agents considered preference for the acts that are available, in addition to EU of those acts. It is the argument of the thesis that when EU is stacked too high against cooperation, it may or may not be rational for an agent to cooperate, depending on which way symbolic utility (SU) for that agent points toward. If SU points in the direction of secession, then it is DV-rational for an agent not to cooperate, but if SU points toward non-secession, then it is DV-rational for that agent to cooperate.

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