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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.
151

Aplicação de sistemas multiagentes para gerenciamento de sistemas de distribuição tipo Smart Grids / Application of multiagent systems for management of distribution systems like Smart Grids

Filipe de Oliveira Saraiva 23 March 2012 (has links)
Os smart grids são tidos como a nova geração dos sistemas elétricos de potência, combinando avanços em computação, sistemas distribuídos e inteligência artificial para prover maiores funcionalidades sobre acompanhamento em tempo real da demanda e do consumo de energia elétrica, gerenciamento em larga escala de geradores distribuídos, entre outras, a partir de um sistema de controle distribuído sobre a rede elétrica. Esta abordagem alteraria fundamentalmente a maneira como se dá o planejamento e a operação de sistemas de distribuição, e há grandes possibilidades de pesquisa e desenvolvimento possibilitada pela busca de implementação destas funcionalidades. Com esse cenário em vista, o presente trabalho utiliza uma abordagem a partir do uso de sistemas multiagentes para estudar o gerenciamento de sistemas de distribuição, do ponto de vista da reconfiguração da topologia da rede, simulando as características de um smart grid. Nesta dissertação, foi desenvolvido um sistema multiagente para simulação computacional de um sistema de distribuição elétrico do tipo smart grid, buscando executar a reconfiguração topológica do sistema a partir de dados de carga capturados de forma distribuída pelos agentes dispersos na rede elétrica. Espera-se que o desenrolar da pesquisa conduza à vários estudos sobre algoritmos e técnicas que melhor implementem tais funcionalidades a serem transpostas para um ambiente de produção. / Smart grids are taken as the new generation of electric power systems, combining advances in computing, distributed systems and artificial intelligence to provide more features on real-time monitoring of demand and consumption of electricity, managing large-scale distributed generators, among others, from a distributed control system on the grid. This approach fundamentally alter the way how is the planning and operation of distribution systems, and there are great possibilities for research and development offered in the quest to implement these features. With that environment, this text uses an approach through the use of multi-agent systems to study the management of the distribution system, from the reconfiguration of grid topology, simulating the characteristics of a smart grid. In this text, was developed a multiagent system to computational simulation of a distribution system like smart grid to topological reconfiguration, from datas collected for agents in electrical grid. It is expected that the conduct of research leads to several studies about better algorithms and techniques that would implement such functionality in a production environment.
152

Uma arquitetura de apoio à interoperabilidade de modelos de reputação de agentes. / An architecture to support the agent reputation models interoperability.

Luis Gustavo Nardin 19 March 2009 (has links)
Em sistemas multiagentes (SMA), a impossibilidade de controle do comportamento interno dos agentes propicia a emergência de dilemas sociais. Uma das possíveis abordagens para resolver tais dilemas é a abordagem social, que tem no conceito de reputação seu principal mecanismo de controle. Para agilizar a obtenção da reputação, torna-se essencial que os agentes cooperem, trocando informações a respeito de reputação. Assim, a partir de diversas observações, avaliações e troca de informações sobre reputação pode-se observar o surgimento da ordem social no sistema global. Entretanto, a heterogeneidade semântica entre os diferentes modelos de reputação torna a interação de agentes um problema, principalmente em SMA abertos. Este trabalho propõe uma arquitetura baseada em serviços, denominada SOARI, para o tratamento deste problema. Esta arquitetura apóia o mapeamento e tradução de conceitos entre ontologias de modelos de reputação distintos através do uso de uma ontologia comum no domínio da reputação. Para ilustrar o uso da arquitetura, foram realizados diversos experimentos nos domínios de comércio eletrônico e de avaliação de obras de arte. Neste último caso, analisou-se os impactos causados nos agentes como conseqüência da habilitação de uma maior expressividade e heterogeneidade na comunicação sobre reputação. / In Multiagent Systems (MAS), controlling the internal agent\'s behavior is impossible and therefore social dilemma may emerge. One possible approach to solve the problem is the social approach, which considers reputation as its main control mechanism. In order to accelerate the reputation evaluation, it is essential that the cooperating agents could exchange information about reputation. Thus, by using observations, evaluations and information exchange about reputation the social order in the global system may occur. However, the semantic heterogeneity of different reputation models makes agent interaction a problem, especially in open MAS. This work proposes a service oriented architecture, named SOARI, to deal with this problem. This architecture supports concept mapping and translation among different reputation model ontologies by using a common ontology. In order to illustrate its deployment, several experiments in the electronic commerce and art appraisal domains were performed. In the latter it was analyzed the effects caused on the agents as a consequence of a more expressive and heterogeneous communication about reputation.
153

Simulação de parcerias entre agentes: uma extensão do sistema PART-NET. / Simulating partnerships among agents: an extension of the PART-NET system.

Júlio de Lima do Rêgo Monteiro 25 June 2004 (has links)
O objetivo deste trabalho é o desenvolvimento de uma ferramenta de simulação baseada em multiagentes para calcular a emergência de parcerias entre múltiplos agentes. A metodologia adotada foi tomar como base o sistema PART-NET [CONTE’98], que efetua o cálculo da emergência de parcerias entre uma dupla de agentes, e alterá-lo de acordo com o objetivo proposto. Dessa maneira, dividiu-se o trabalho em duas etapas. Na primeira, o sistema original foi reescrito na linguagem Java, promovendo benefícios operacionais, como a melhora da interface e a apresentação dos resultados de forma gráfica. Esse sistema intermediário foi denominado PartNET+. A segunda etapa constituiu-se em expandir a funcionalidade do sistema intermediário, tornando sua arquitetura de agentes mais completa pela adição de planos, o que permite novos tipos de parcerias. Para processar essas parcerias, criou-se um novo algoritmo para cálculo de parcerias entre múltiplos agentes, com base em hipergrafos. O sistema resultante, que compreende estas extensões funcionais, foi denominado PartNET++. / The purpose of this work is the development of a multiagent based simulation tool to account partnership formation among multiple agents. In order to achieve that, the PART-NET [CONTE’98] system was adopted as a base. This system calculates the partnership formation of pairs of agents, and was altered according to the proposed objective. In this manner, the work was divided in two stages. In the first, the original system was redesigned using the Java language, bringing operational improvements to the predecessor, such as user interface enhancement and graphical display of the results. This intermediary system was named PartNET+. The second stage promotes new functionality to this intermediary system, adding plans to its agent architecture to allow new kinds of partnerships. A new algorithm for multiple agents partnership formation was developed based on hipergraphs, and the final system that handles this enhanced partnership formation was called PartNET++
154

Modelagem e simulação de agentes com aspectos cognitivos para avaliação de comportamento social. / Modeling and simulation of agents with congnitive aspects to evaluate social behavior.

Daniel Costa de Paiva 12 May 2011 (has links)
Este trabalho foi elaborado considerando conceitos de quatro áreas de pesquisa: ciência da computação, ciência cognitiva, ciência da informação e comunicação social. A contribuição principal aqui se dá em definir agentes minimamente cognitivos que participam ativamente na dinâmica do fluxo de informações, sofrendo influência das mensagens que recebem e também interferindo no que irá passar adiante. O modelo contempla tanto características relacionadas ao ambiente e sociedade, definidos usando ontologias, quanto à mente, arquitetura e funcionamento dos agentes. Cada personagem possui três módulos de decisão, podendo acessar meios de comunicação em massa, assimilar informações recebidas e também falar com seus amigos. Para o módulo de assimilação, estão apresentadas quatro formas que os agentes podem usar para avaliar as informações que recebem. Primeiramente foi elaborada uma função, depois foram definidas três máquinas de estados finitos, aumentando gradativamente a complexidade e a interdependência entre os parâmetros envolvidos em cada uma. Foi também elaborada uma função adaptativa, a qual a partir de uma regra definida pelo usuário para a troca entre as máquinas de estado que os agentes dispõem, propiciou resultados satisfatórios mesmo nos casos onde alguma das máquinas de estado apresentou deficiências. Visando reproduzir uma situação inspirada na vida real, estão apresentados resultados de uma versão combinada (definida pelo autor) onde foram considerados três grupos e a possibilidade de acesso a meios de comunicação em massa e/ou troca de mensagens entre amigos. Usando o modelo como base, um simulador foi desenvolvido onde é possível ter não só uma visão global da dinâmica que está acontecendo na sociedade, mas também o que alguns agentes ficam sabendo e que podem falar sobre. Os estudos de caso visaram comparar as diferentes formas de assimilação de informações que os agentes podem usar (elaboradas pelo autor), avaliar a influência da variação de alguns parâmetros e reproduzir a dinâmica do fluxo de informações em redes sociais, a comparando com o que acontece quando se tem a divulgação broadcast. / This work was developed considering concepts of four research areas: computer science, cognitive science, information science and social communication. The main contribution here is to define minimally cognitive agents who actively participate in dynamic of information flow interfering on the messages received and are being affected by them. The model consider characteristics related to the environment and the society, defined by using ontologies, and the \"mind\", architecture and functioning of the agents. Each character has three decision modules. They can access means of mass communication, assimilate information received and talk to their friends. To the assimilation module were presented four forms that agents can evaluate received information, a function, and three finite state machines (FSM). They were elaborated increasing the complexity. After, it was developed an adaptive function, in which using a rule the user define how to exchange between the finite state machines that agents have. This function provided satisfactory results even in cases where some of the FSMs presented problems. Aiming to reproduce a situation inspired in real life a combined version was defined by the author, in where were considered three groups that can access means of mass communication and / or talk to their friends. Based on the model, a simulator was developed in which there are not only an overview of the society dynamics, but also what agents learn and what they can talk about. The case studies were performed aiming to compare the different assimilation forms (developed by the author), to evaluate the influence of some parameters variation and to reproduce the dynamics of information flow, comparing the influence of a social network communication and the mass communication activity.
155

Influência da complexidade da representação de estratégias em modelos evolucionários para o dilema do prisioneiro com n jogadores. / Influence of strategy representation complexity in evolutionary models for the n-players Prisoner\'s Dilemma.

Inácio Guerberoff Lanari Bó 19 December 2007 (has links)
Em Teoria dos Jogos, o Dilema do Prisioneiro para N Participantes (DPNP) é o problema que representa, em sua forma elementar, o paradoxo que gera as dificuldades existentes na formação da cooperação entre mais de dois agentes. Diversos trabalhos foram e continuam sendo feitos sobre esse tema, no sentido de compreender melhor os fatores que influenciam o surgimento e a evolução da cooperação numa sociedade. Neste trabalho, o objetivo principal é o de analisar o impacto do poder expressivo de um modelo de representação de estratégias neste surgimento e evolução. Para tal, foi desenvolvido um modelo computacional de jogos evolutivos, onde agentes participam repetidamente do DPNP. Nele, as estratégias que definem qual será a jogada de um determinado agente são desenvolvidas e selecionadas através de mecanismos de mutação e reprodução daquelas que obtiveram melhores resultados nas iterações anteriores, e implementadas através de duas representações com diferentes poderes computacionais: autômatos finitos e autômatos adaptativos. Este modelo foi implementado num sistema denominado S2E2 onde foram executados diversos experimentos de simulação. Através da comparação dos resultados obtidos para ambas as representações, verificou-se que em ambos os casos a sociedade consegue atingir, após um período inicial, um nível de cooperação relativamente alto e estável. A análise das estratégias utilizadas pelos agentes, entretanto, mostrou que o uso de autômatos adaptativos resulta em uma pequena vantagem, embora estatisticamente não significativa, pois permite surgir estratégias que visam retornar a uma situação de cooperação. / In Game Theory, the n-Players Prisoner\'s Dilemma (NPPD) is a problem that represents, in its elementary form, the paradox that leads to the existing difficulties in the development of cooperation between two or more agents. Many works were and are still being done about this subject, trying to better understand the factors that influence the development and evolution of cooperation in a society. In this work, the main objective is to analyze the impact of the expressive power of the strategies representation model in this development and evolution. In order to do so, a computational model of evolutionary games was developed, where agents are spatially distributed and participate on the NPPD with five participants, interacting only with their neighbors. In this model, the strategies that define the agent\'s decisions are developed and selected through mutation and reproduction of those strategies that obtained better results in the last iterations, and they are implemented by two representations with different computational power: finite automata and adaptative automata. This model was implemented in a system called S2E2 and several simulation experiments were carried on. Comparing the results obtained in those experiments, it was verified that after an initial period of time in both cases the society achieved a relatively high and stable level of cooperation. On the other hand, the analysis of the strategies used by the agents showed that the use of adaptative automata resulted in a slight advantage, although not statistically significative, because they allow the emergence of strategies that return to a situation of cooperation.
156

Uma arquitetura de apoio à interoperabilidade de modelos de reputação de agentes. / An architecture to support the agent reputation models interoperability.

Nardin, Luis Gustavo 19 March 2009 (has links)
Em sistemas multiagentes (SMA), a impossibilidade de controle do comportamento interno dos agentes propicia a emergência de dilemas sociais. Uma das possíveis abordagens para resolver tais dilemas é a abordagem social, que tem no conceito de reputação seu principal mecanismo de controle. Para agilizar a obtenção da reputação, torna-se essencial que os agentes cooperem, trocando informações a respeito de reputação. Assim, a partir de diversas observações, avaliações e troca de informações sobre reputação pode-se observar o surgimento da ordem social no sistema global. Entretanto, a heterogeneidade semântica entre os diferentes modelos de reputação torna a interação de agentes um problema, principalmente em SMA abertos. Este trabalho propõe uma arquitetura baseada em serviços, denominada SOARI, para o tratamento deste problema. Esta arquitetura apóia o mapeamento e tradução de conceitos entre ontologias de modelos de reputação distintos através do uso de uma ontologia comum no domínio da reputação. Para ilustrar o uso da arquitetura, foram realizados diversos experimentos nos domínios de comércio eletrônico e de avaliação de obras de arte. Neste último caso, analisou-se os impactos causados nos agentes como conseqüência da habilitação de uma maior expressividade e heterogeneidade na comunicação sobre reputação. / In Multiagent Systems (MAS), controlling the internal agent\'s behavior is impossible and therefore social dilemma may emerge. One possible approach to solve the problem is the social approach, which considers reputation as its main control mechanism. In order to accelerate the reputation evaluation, it is essential that the cooperating agents could exchange information about reputation. Thus, by using observations, evaluations and information exchange about reputation the social order in the global system may occur. However, the semantic heterogeneity of different reputation models makes agent interaction a problem, especially in open MAS. This work proposes a service oriented architecture, named SOARI, to deal with this problem. This architecture supports concept mapping and translation among different reputation model ontologies by using a common ontology. In order to illustrate its deployment, several experiments in the electronic commerce and art appraisal domains were performed. In the latter it was analyzed the effects caused on the agents as a consequence of a more expressive and heterogeneous communication about reputation.
157

Simulação de parcerias entre agentes: uma extensão do sistema PART-NET. / Simulating partnerships among agents: an extension of the PART-NET system.

Monteiro, Júlio de Lima do Rêgo 25 June 2004 (has links)
O objetivo deste trabalho é o desenvolvimento de uma ferramenta de simulação baseada em multiagentes para calcular a emergência de parcerias entre múltiplos agentes. A metodologia adotada foi tomar como base o sistema PART-NET [CONTE’98], que efetua o cálculo da emergência de parcerias entre uma dupla de agentes, e alterá-lo de acordo com o objetivo proposto. Dessa maneira, dividiu-se o trabalho em duas etapas. Na primeira, o sistema original foi reescrito na linguagem Java, promovendo benefícios operacionais, como a melhora da interface e a apresentação dos resultados de forma gráfica. Esse sistema intermediário foi denominado PartNET+. A segunda etapa constituiu-se em expandir a funcionalidade do sistema intermediário, tornando sua arquitetura de agentes mais completa pela adição de planos, o que permite novos tipos de parcerias. Para processar essas parcerias, criou-se um novo algoritmo para cálculo de parcerias entre múltiplos agentes, com base em hipergrafos. O sistema resultante, que compreende estas extensões funcionais, foi denominado PartNET++. / The purpose of this work is the development of a multiagent based simulation tool to account partnership formation among multiple agents. In order to achieve that, the PART-NET [CONTE’98] system was adopted as a base. This system calculates the partnership formation of pairs of agents, and was altered according to the proposed objective. In this manner, the work was divided in two stages. In the first, the original system was redesigned using the Java language, bringing operational improvements to the predecessor, such as user interface enhancement and graphical display of the results. This intermediary system was named PartNET+. The second stage promotes new functionality to this intermediary system, adding plans to its agent architecture to allow new kinds of partnerships. A new algorithm for multiple agents partnership formation was developed based on hipergraphs, and the final system that handles this enhanced partnership formation was called PartNET++
158

SOSIEL: a Cognitive, Multi-Agent, and Knowledge-Based Platform for Modeling Boundedly-Rational Decision-Making

Sotnik, Garry 01 February 2018 (has links)
Decision-related activities, such as bottom-up and top-down policy development, analysis, and planning, stand to benefit from the development and application of computer-based models that are capable of representing spatiotemporal social human behavior in local contexts. This is especially the case with our efforts to understand and search for ways to mitigate the context-specific effects of climate change, in which case such models need to include interacting social and ecological components. The development and application of such models has been significantly hindered by the challenges in designing artificial agents whose behavior is grounded in both empirical evidence and theory and in testing the ability of artificial agents to represent the behavior of real-world decision-makers. This dissertation advances our ability to develop such models by overcoming these challenges through the creation of: (a) three new frameworks, (b) two new methods, and (c) two new open-source modeling tools. The three new frameworks include: (a) the SOSIEL framework, which provides a theoretically-grounded blueprint for the development of a new generation of cognitive, multi-agent, and knowledge-based models that consist of agents empowered with cognitive architectures; (b) a new framework for analyzing the bounded rationality of decision-makers, which offers insight into and facilitates the analysis of the relationship between a decision situation and a decision-maker's decision; and (c) a new framework for analyzing the doubly-bounded rationality (DBR) of artificial agents, which does the same for the relationship between a decision situation and an artificial agent's decision. The two new methods include: (a) the SOSIEL method for acquiring and operationalizing decision-making knowledge, which advances our ability to acquire, process, and represent decision-making knowledge for cognitive, multi-agent, and knowledge-based models; and (b) the DBR method for testing the ability of artificial agents to represent human decision-making. The two open-source modeling tools include: (a) the SOSIEL platform, which is a cognitive, multi-agent, and knowledge-based platform for simulating human decision-making; and (b) an application of the platform as the SOSIEL Human Extension (SHE) to an existing forest-climate change model, called LANDIS-II, allowing for the analysis of co-evolutionary human-forest-climate interactions. To provide a context for examples and also guidelines for knowledge acquisition, the dissertation includes a case study of social-ecological interactions in an area of the Ukrainian Carpathians where LANDIS-II with SHE are currently being applied. As a result, this dissertation advances science by: (a) providing a theoretical foundation for and demonstrating the implementation of a next generation of models that are cognitive, multi-agent, and knowledge-based; and (b) providing a new perspective for understanding, analyzing, and testing the ability of artificial agents to represent human decision-making that is rooted in psychology.
159

Driver Distraction in Microsimulation of a Mid-Block Pedestrian Crossing

Michaud, Darryl Joseph 18 September 2018 (has links)
Traffic simulation has become an invaluable part of the traffic engineering toolbox. However, the majority of driver models are designed to recreate traffic performance based on interactions among vehicles. In keeping with this pursuit, most are fundamentally built to avoid collisions. This limits the applicability of using these models for addressing safety concerns, especially those regarding pedestrian safety performance. However, by explicitly including some of the sources of human error, these limitations can, in theory, be overcome. While much work has been done toward including these human factors in simulation platforms, one key aspect of human behavior has been largely ignored: driver distraction. This work presents a novel approach to inclusion of driver distraction in a microsimulation or agent-based model. Distributions of distraction events and inter-distraction periods are derived from eye-glance data collected during naturalistic driving studies. The developed model of distraction is implemented -- along with perception errors, visual obstructions, and driver reaction times -- in a simulated mid-block pedestrian crossing. The results of this simulation demonstrate that excluding any of these human factors from the implemented driver model significantly alters conflict rates observed in the simulation. This finding suggests that inclusion of human factors is important in any microsimulation platforms used to analyze pedestrian safety performance.
160

Agent-based modeling of the social and economic factors affecting the choice of transportation mode : application to the Beirut city / Modélisation orientée agent des facteurs sociaux et économiques affectant le choix du mode de transport : application à la ville de Beyrouth

El amine, Samar 11 December 2018 (has links)
En milieu urbain et périurbain, les transports et la mobilité sont étroitement liés aux activités socio-économiques. Ils sont influencés par la psychologie personnelle de l'individu, les normes sociales, la résistance au changement, l'attitude personnelle, les habitudes, les peurs et les croyances. A Beyrouth, la possession de véhicules a augmenté rapidement en raison de la pénurie de transports en commun amenant l’opportunité de développer des services de mobilité durable et d’accessibilité. Cela nécessite que les modes de transport soient abordables, efficaces et respectueux de l'environnement, ainsi que des technologies qui minimisent la consommation d'énergie en mettant l'accent sur trois points principaux: réduire les besoins de déplacement, adopter des modes de transport plus respectueux de l'environnement et améliorer l'efficacité de la technologie des véhicules. Cette thèse porte sur la modélisation orientée-agent du comportement de déplacement. Nous avons analysé les données obtenues à partir d’une enquête menée à Beyrouth. Une relation entre l’emploi, le statut social et le choix du mode de transport a été mise en évidence. Un modèle de simulation orientée agent, incluant les architectures et les algorithmes des agents, du trafic routier utilisant une approche économique institutionnelle a été proposé. Les questions scientifiques concernent les effets de facteurs économiques, sociaux, professionnels et liés aux ménages sur le choix d'un mode de transport. Ce travail fait partie d'un projet de la société S&A (Belgique et Liban) visant à fournir des outils permettant la transition des moyens de transport vers une pratique plus respectueuse. / In urban and peri-urban environments, transport and mobility are strongly linked to socio-economic activities. They are influenced by individual's personal psychology, social norms, resistance to change, personal attitude, habits, fears and beliefs. Beirut is a mono-centric city with transport supply poverty. Vehicle ownership has increased rapidly in response to the shortage of public transportation. Currently, there is an opportunity to develop mobility management services and establish sustainable mobility and accessibility in Beirut. This requires that transport modes be affordable, efficient and environmentally friendly, as well as technologies that minimize the energy consumption by focusing on three main points: reducing travel needs, adopting more environmentally friendly modes of transportation, and improving the efficiency of vehicle technology. This thesis focuses on the modeling of displacement behavior, based on agent-oriented modeling. We analyzed the data obtained from a survey we conducted for Beirut. We established a relation between employment, social status and mode of transportation selection. The subject of the thesis is an agent-oriented simulation model of road traffic using an institutional economic approach. We propose an architecture, algorithms and methods to implement the agents model in order to model and reproduce their modes of transport behavior. Associated scientific questions are the effects of economic, social, career and household factors on choosing a mode of transport. This work is part of a project of the company S&A (Belgium and Lebanon) to provide tools to enable the transition of means of transport to a more respectful practice.

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