853 resultados para Probabilistic decision process model
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Dissertação (mestrado)—Universidade de Brasília, Centro de Desenvolvimento Sustentável, 2014.
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Background: Rotavirus diarrhea is one of the most important causes of death among under-five children. Anti-rotavirus vaccination of these children may have a reducing effect on the disease. Objectives: this study is intended to contribute to health policy-makers of the country about the optimal decision and policy development in this area, by performing cost-effectiveness and cost-utility analysis on anti-rotavirus vaccination for under-5 children. Patients and Methods: A cost-effectiveness analysis was performed using a decision tree model to analyze rotavirus vaccination, which was compared with no vaccination with Iran’s ministry of health perspective in a 5-year time horizon. Epidemiological data were collected from published and unpublished sources. Four different assumptions were considered to the extent of the disease episode. To analyze costs, the costs of implementing the vaccination program were calculated with 98% coverage and the cost of USD 7 per dose. Medical and social costs of the disease were evaluated by sampling patients with rotavirus diarrhea, and sensitivity analysis was also performed for different episode rates and vaccine price per dose. Results: For the most optimistic assumption for the episode of illness (10.2 per year), the cost per DALY averted is 12,760 and 7,404 for RotaTeq and Rotarix vaccines, respectively, while assuming the episode of illness is 300%, they will be equal to 2,395 and 354, respectively, which will be highly cost-effective. Number of life-years gained is equal to 3,533 years. Conclusions: Assuming that the illness episodes are 100% and 300% for Rotarix and 300% for Rota Teq, the ratio of cost per DALY averted is highly cost-effective, based on the threshold of the world health organization (< 1 GDP per capita = 4526 USD). The implementation of a national rotavirus vaccination program is suggested.
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To stay competitive, many employers are looking for creative and innovative employees to add value to their organization. However, current models of job performance overlook creative performance as an important criterion to measure in the workplace. The purpose of this dissertation is to conduct two separate but related studies on creative performance that aim to provide support that creative performance should be included in models of job performance, and ultimately included in performance evaluations in organizations. Study 1 is a meta-analysis on the relationship between creative performance and task performance, and the relationship between creative performance and organizational citizenship behavior (OCB). Overall, I found support for a medium to large corrected correlation for both the creative performance-task performance (ρ = .51) and creative performance-OCB (ρ = .49) relationships. Further, I also found that both rating-source and study location were significant moderators. Study 2 is a process model that includes creative performance alongside task performance and OCB as the outcome variables. I test a model in which both individual differences (specifically: conscientiousness, extraversion, proactive personality, and self-efficacy) and job characteristics (autonomy, feedback, and supervisor support) predict creative performance, task performance, and OCB through engagement as a mediator. In a sample of 299 employed individuals, I found that all the individual differences and job characteristics were positively correlated with all three performance criteria. I also looked at these relationships in a multiple regression framework and most of the individual differences and job characteristics still predicted the performance criteria. In the mediation analyses, I found support for engagement as a significant mediator of the individual differences-performance and job characteristics-performance relationships. Taken together, Study 1 and Study 2 support the notion that creative performance should be included in models of job performance. Implications for both researchers and practitioners alike are discussed.^
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Perceived accessibility has been acknowledged as an important aspect of transport policy since the 70s. Nevertheless, very few empirical studies have been conducted in this field. When aiming to improve social inclusion, by making sus-tainable transport modes accessible to all, it is important to understand the factors driving perceived accessibility. Un-like conventional accessibility measures, perceived accessibility focuses on the perceived possibilities and ease of en-gaging in preferred activities using different transport modes. We define perceived accessibility in terms of how easy it is to live a satisfactory life with the help of the transport system, which is not necessarily the same thing as the objec-tive standard of the system. According to previous research, perceived accessibility varies with the subjectively-rated quality of the mode of transport. Thus, improvements in quality (e.g. trip planning, comfort, or safety) increase the per-ceived accessibility and make life easier to live using the chosen mode of transport. This study (n=750) focuses on the perceived accessibility of public transport, captured using the Perceived Accessibility Scale PAC (Lättman, Olsson, & Fri-man, 2015). More specifically, this study aims to determine how level of quality affects the perceived accessibility in public transport. A Conditional Process Model shows that, in addition to quality, feeling safe and frequency of travel are important predictors of perceived accessibility. Furthermore, elderly and those in their thirties report a lower level of perceived accessibility to their day-to-day activities using public transport. The basic premise of this study is that sub-jective experiences may be as important as objective indicators when planning and designing for socially inclusive transport systems.
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Résumé : Contexte: Les maladies cardiovasculaires (MCV) sont un enjeu contemporain de santé publique. Or, des recherches cliniques démontrent que certaines interventions sont efficaces dans leur traitement et prévention. Il s’agit d’interventions nutritionnelles éducatives priorisant des aliments végétaux minimalement transformés (VMT). Ces interventions promeuvent l’adoption de postures alimentaires se caractérisant par la consommation à volonté d’une grande variété d’aliments d’origine végétale (e.g. légumineuses, céréales entières, fruits, légumes) et par une diminution de la consommation d’aliments d’origine animale (e.g. viandes, œufs et produits laitiers) et ultra-transformés (e.g. riches en sucres, sel ou gras, et faibles en fibres). Objectifs: À l’aide d’un devis mixte concomitant imbriqué, nous avons évalué les effets d’un programme d’interventions éducatives visant à augmenter la consommation de VMT chez des adultes à risque de MCV et exploré les déterminants des modifications comportementales observées. Méthodologie : Divers paramètres physiologiques et anthropométriques ont été mesurés pré-post programme (n = 72) puis analysés avec un test t pour échantillons appariés ou un test signé des rangs de Wilcoxon. D’autre part, 10 entretiens semi-dirigés ont été réalisés post-programme et soutenus par un guide d’entretien basé sur le Food Choice Process Model. Les verbatims intégraux ont été codés selon la méthode d’analyse thématique. Résultats : Après 12 semaines, le poids (-10,5 lb, IC 95 %: 9,0-12,0), le tour de taille (-7,4 cm, IC 95 %:6,5-8,4), la tension artérielle diastolique (-3,2 mmHg, IC 95 %: 0,1-6,3), le cholestérol total (-0,87 mmol/ L, IC 95 %:0,57-1,17), le cholestérol LDL (-0,84 mmol/ L, IC 95 %: 0,55-1,13) et l’hémoglobine glyquée (-1,32 %, IC 95 %:-0,17-2,80) se sont significativement améliorés. L’analyse thématique des données qualitatives révèle que le programme, par la stimulation de valeurs de santé, d’éthique et d’intégrité, favorise la transformation des choix alimentaires vers une posture davantage axée sur les VMT durant une période clé du parcours de vie (i.e. pré-retraite). D’autres déterminants pouvant favoriser l’adoption d’une alimentation VMT ont été identifiés, dont les bénéfices importants observables à court terme, l’absence de restriction à l’égard de la quantité d’aliments VMT et le développement de compétences de planification dans l’acquisition et la préparation des aliments. Conclusion : Une intervention priorisant les VMT permet d’améliorer le profil cardiométabolique d’individus pré-retraités en raison de ses caractéristiques intrinsèques, mais aussi parce qu’elle modifie les valeurs impliquées dans les choix alimentaires.
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With an increasing demand for rural resources and land, new challenges are approaching affecting and restructuring the European countryside. While creating opportunities for rural living, it has also opened a discussion on rural gentrification risks. The concept of rural gentrification encircles the influx of new residents leading to an economic upgrade of an area making it unaffordable for local inhabitants to stay in. Rural gentrification occurs in areas perceived as attractive. Paradoxically, in-migrants re-shape their surrounding landscape. Rural gentrification may not only cause displacement of people but also landscape values. Thus, this research aims to understand the twofold role of landscape in rural gentrification theory: as a possible driver to attract residents and as a product shaped by its residents. To understand the potential gentrifiers’ decision process, this research has provided a collection of drivers behind in-migration. Moreover, essential indicators of rural gentrification have been collected from previous studies. Yet, the available indicators do not contain measures to understand related landscape changes. To fill this gap, after analysing established landscape assessment methodologies, evaluating the relevance for assessing gentrification, a new Landscape Assessment approach is proposed. This method introduces a novel approach to capture landscape change caused by gentrification through a historical depth. The measures to study gentrification was applied on Gotland, Sweden. The study showed a population stagnating while the number of properties increased, and housing prices raised. These factors are not indicating positive growth but risks of gentrification. Then, the research applied the proposed Landscape Assessment method for areas exposed to gentrification. Results suggest that landscape change takes place on a local scale and could over time endanger key characteristics. The methodology contributes to a discussion on grasping nuances within the rural context. It has also proven useful for indicating accumulative changes, which is necessary in managing landscape values.
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Over the last century, mathematical optimization has become a prominent tool for decision making. Its systematic application in practical fields such as economics, logistics or defense led to the development of algorithmic methods with ever increasing efficiency. Indeed, for a variety of real-world problems, finding an optimal decision among a set of (implicitly or explicitly) predefined alternatives has become conceivable in reasonable time. In the last decades, however, the research community raised more and more attention to the role of uncertainty in the optimization process. In particular, one may question the notion of optimality, and even feasibility, when studying decision problems with unknown or imprecise input parameters. This concern is even more critical in a world becoming more and more complex —by which we intend, interconnected —where each individual variation inside a system inevitably causes other variations in the system itself. In this dissertation, we study a class of optimization problems which suffer from imprecise input data and feature a two-stage decision process, i.e., where decisions are made in a sequential order —called stages —and where unknown parameters are revealed throughout the stages. The applications of such problems are plethora in practical fields such as, e.g., facility location problems with uncertain demands, transportation problems with uncertain costs or scheduling under uncertain processing times. The uncertainty is dealt with a robust optimization (RO) viewpoint (also known as "worst-case perspective") and we present original contributions to the RO literature on both the theoretical and practical side.
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We consider multistage stochastic linear optimization problems combining joint dynamic probabilistic constraints with hard constraints. We develop a method for projecting decision rules onto hard constraints of wait-and-see type. We establish the relation between the original (in nite dimensional) problem and approximating problems working with projections from di erent subclasses of decision policies. Considering the subclass of linear decision rules and a generalized linear model for the underlying stochastic process with noises that are Gaussian or truncated Gaussian, we show that the value and gradient of the objective and constraint functions of the approximating problems can be computed analytically.
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This paper presents an effective decision making system for leak detection based on multiple generalized linear models and clustering techniques. The training data for the proposed decision system is obtained by setting up an experimental pipeline fully operational distribution system. The system is also equipped with data logging for three variables; namely, inlet pressure, outlet pressure, and outlet flow. The experimental setup is designed such that multi-operational conditions of the distribution system, including multi pressure and multi flow can be obtained. We then statistically tested and showed that pressure and flow variables can be used as signature of leak under the designed multi-operational conditions. It is then shown that the detection of leakages based on the training and testing of the proposed multi model decision system with pre data clustering, under multi operational conditions produces better recognition rates in comparison to the training based on the single model approach. This decision system is then equipped with the estimation of confidence limits and a method is proposed for using these confidence limits for obtaining more robust leakage recognition results.
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The purpose of this study was to gain a better understanding of the foreign direct investment location decision making process through the examination of non-Western investors and their investment strategies in non-traditional markets. This was accomplished through in-depth personal interviews with 50 Overseas Chinese business owners and executives in several different industries from Hong Kong, Singapore, Taiwan, Malaysia, and Thailand about 97 separate investment projects in Southeast and East Asia, including The Philippines, Malaysia, Hong Kong, Singapore, Vietnam, India, Pakistan, South Korea, Australia, Indonesia, Cambodia, Thailand, Burma, Taiwan, and Mainland China.^ Traditional factors utilized in Western models of the foreign direct investment decision making process are reviewed, as well as literature on Asian management systems and the current state of business practices in emerging countries of Southeast and East Asia. Because of the lack of institutionalization in these markets and the strong influences of Confucian and patriarchal value systems on the Overseas Chinese, it was suspected that while some aspects of Western rational economic models of foreign direct investment are utilized, these models are insufficient in this context, and thus are not fully generalizable to the unique conditions of the Overseas Chinese business network in the region without further modification.^ Thus, other factors based on a Confucian value system need to be integrated into these models. Results from the analysis of structured interviews suggest Overseas Chinese businesses rely more heavily on their network and traditional Confucian values than rational economic factors when making their foreign direct investment location decisions in emerging countries in Asia. This effect is moderated by the firm's industry and the age of the firm's owners. ^
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Fatigue and crack propagation are phenomena affected by high uncertainties, where deterministic methods fail to predict accurately the structural life. The present work aims at coupling reliability analysis with boundary element method. The latter has been recognized as an accurate and efficient numerical technique to deal with mixed mode propagation, which is very interesting for reliability analysis. The coupled procedure allows us to consider uncertainties during the crack growth process. In addition, it computes the probability of fatigue failure for complex structural geometry and loading. Two coupling procedures are considered: direct coupling of reliability and mechanical solvers and indirect coupling by the response surface method. Numerical applications show the performance of the proposed models in lifetime assessment under uncertainties, where the direct method has shown faster convergence than response surface method. (C) 2010 Elsevier Ltd. All rights reserved.
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This paper describes a process-based metapopulation dynamics and phenology model of prickly acacia, Acacia nilotica, an invasive alien species in Australia. The model, SPAnDX, describes the interactions between riparian and upland sub-populations of A. nilotica within livestock paddocks, including the effects of extrinsic factors such as temperature, soil moisture availability and atmospheric concentrations of carbon dioxide. The model includes the effects of management events such as changing the livestock species or stocking rate, applying fire, and herbicide application. The predicted population behaviour of A. nilotica was sensitive to climate. Using 35 years daily weather datasets for five representative sites spanning the range of conditions that A. nilotica is found in Australia, the model predicted biomass levels that closely accord with expected values at each site. SPAnDX can be used as a decision-support tool in integrated weed management, and to explore the sensitivity of cultural management practices to climate change throughout the range of A. nilotica. The cohort-based DYMEX modelling package used to build and run SPAnDX provided several advantages over more traditional population modelling approaches (e.g. an appropriate specific formalism (discrete time, cohort-based, process-oriented), user-friendly graphical environment, extensible library of reusable components, and useful and flexible input/output support framework). (C) 2003 Published by Elsevier Science B.V.
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This thesis presents the Fuzzy Monte Carlo Model for Transmission Power Systems Reliability based studies (FMC-TRel) methodology, which is based on statistical failure and repair data of the transmission power system components and uses fuzzyprobabilistic modeling for system component outage parameters. Using statistical records allows developing the fuzzy membership functions of system component outage parameters. The proposed hybrid method of fuzzy set and Monte Carlo simulation based on the fuzzy-probabilistic models allows catching both randomness and fuzziness of component outage parameters. A network contingency analysis to identify any overloading or voltage violation in the network is performed once obtained the system states. This is followed by a remedial action algorithm, based on Optimal Power Flow, to reschedule generations and alleviate constraint violations and, at the same time, to avoid any load curtailment, if possible, or, otherwise, to minimize the total load curtailment, for the states identified by the contingency analysis. For the system states that cause load curtailment, an optimization approach is applied to reduce the probability of occurrence of these states while minimizing the costs to achieve that reduction. This methodology is of most importance for supporting the transmission system operator decision making, namely in the identification of critical components and in the planning of future investments in the transmission power system. A case study based on Reliability Test System (RTS) 1996 IEEE 24 Bus is presented to illustrate with detail the application of the proposed methodology.
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Dissertação para obtenção do Grau de Mestre em Engenharia e Gestão Industrial
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Given the current economic situation of the Portuguese municipalities, it is necessary to identify the priority investments in order to achieve a more efficient financial management. The classification of the road network of the municipality according to the occurrence of traffic accidents is fundamental to set priorities for road interventions. This paper presents a model for road network classification based on traffic accidents integrated in a geographic information system. Its practical application was developed through a case study in the municipality of Barcelos. An equation was defined to obtain a road safety index through the combination of the following indicators: severity, property damage only and accident costs. In addition to the road network classification, the application of the model allows to analyze the spatial coverage of accidents in order to determine the centrality and dispersion of the locations with the highest incidence of road accidents. This analysis can be further refined according to the nature of the accidents namely in collision, runoff and pedestrian crashes.