Implementação e análise de uma arquitetura de grids de agentes para a gerência de redes e sistemas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.O gerenciamento centralizado de redes de computadores, telecomunicações e de sistemas pode nos levar a situações em que grandes volumes de dados precisam ser manipulados e analisados por uma única estação de gerenciamento na rede. Além do alto custo, tal abordagem tem se apresentado pouco extensível à medida que cresce o número de dispositivos no ambiente gerenciado. Frente a este problema, este trabalho apresenta uma arquitetura baseada em grids de agentes aplicável ao gerenciamento de redes de computadores e de sistemas. Tal abordagem tem como objetivo básico aplicar princípios da computação em grid, usando agentes de software como infra-estrutura para construção do grid, com o objetivo de otimizar alguns problemas inerentes ao gerenciamento centralizado como a manipulação e análise de grande volume de informação de gerenciamento. Também no escopo deste trabalho são descritos detalhes de implementação da arquitetura de grid proposta e a realização de experimentos em cenários de gerenciamento de sistemas usando um sistema baseado na proposta apresentada

Analysis Of Aircraft Arrival Delay And Airport On-time Performance

While existing grid environments cater to specific needs of a particular user community, we need to go beyond them and consider general-purpose large-scale distributed systems consisting of large collections of heterogeneous computers and communication systems shared by a large user population with very diverse requirements. Coordination, matchmaking, and resource allocation are among the essential functions of large-scale distributed systems. Although deterministic approaches for coordination, matchmaking, and resource allocation have been well studied, they are not suitable for large-scale distributed systems due to the large-scale, the autonomy, and the dynamics of the systems. We have to seek for nondeterministic solutions for large-scale distributed systems. In this dissertation we describe our work on a coordination service, a matchmaking service, and a macro-economic resource allocation model for large-scale distributed systems. The coordination service coordinates the execution of complex tasks in a dynamic environment, the matchmaking service supports finding the appropriate resources for users, and the macro-economic resource allocation model allows a broker to mediate resource providers who want to maximize their revenues and resource consumers who want to get the best resources at the lowest possible price, with some global objectives, e.g., to maximize the resource utilization of the system

A Methodology for Modelling Mobile Agent-Based Systems (Mobile agent Mobility Methodology - MaMM)

Mobile agents are a particular type of agents that have all the characteristics of an agent and also demonstrate the ability to move or migrate from one node to another in a network environment. Mobile agents have received considerable attention from industry and the research community in recent times due to the fact that their special characteristic of migration help address issues such as network overload, network latency and protocol encapsulation. Due to the current focus in exploiting agent technology mainly in a research environment, there has been an influx of software engineering methodologies for developing multi-agent systems. However, little attention has been given to modelling mobile agents. For mobile agent-based systems to become more widely accepted there is a critical need for a methodology to be developed to address various issues related to modelling mobility of agent . This research study provides an overview of the current approaches, methodologies and modelling languages that can be used for developing multi-agent systems. The overview indicates extensive research on methodologies for modelling multi-agent systems and little on mobility in mobile agent-based systems. An original contribution in this research known as Mobile agent-based Mobility Methodology (MaMM) is the methodology for modelling mobility in mobile agent-based systems using underlying principles of Genetic Algorithms (GA) with emphasis on fitness functions and genetic representation. Delphi study and case studies were employed in carrying out this research

Learning plan networks in conversational video games

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2007.Includes bibliographical references (p. 121-123).We look forward to a future where robots collaborate with humans in the home and workplace, and virtual agents collaborate with humans in games and training simulations. A representation of common ground for everyday scenarios is essential for these agents if they are to be effective collaborators and communicators. Effective collaborators can infer a partner's goals and predict future actions. Effective communicators can infer the meaning of utterances based on semantic context. This thesis introduces a computational cognitive model of common ground called a Plan Network. A Plan Network is a statistical model that provides representations of social roles, object affordances, and expected patterns of behavior and language. I describe a methodology for unsupervised learning of a Plan Network using a multiplayer video game, visualization of this network, and evaluation of the learned model with respect to human judgment of typical behavior. Specifically, I describe learning the Restaurant Plan Network from data collected from over 5,000 players of an online game called The Restaurant Game.by Jeffrey David Orkin.S.M

Mac Layer And Routing Protocols For Wireless Ad Hoc Networks With Asymmetric Links And Performance Evaluation Studies

In a heterogeneous mobile ad hoc network (MANET), assorted devices with different computation and communication capabilities co-exist. In this thesis, we consider the case when the nodes of a MANET have various degrees of mobility and range, and the communication links are asymmetric. Many routing protocols for ad hoc networks routinely assume that all communication links are symmetric, if node A can hear node B and node B can also hear node A. Most current MAC layer protocols are unable to exploit the asymmetric links present in a network, thus leading to an inefficient overall bandwidth utilization, or, in the worst case, to lack of connectivity. To exploit the asymmetric links, the protocols must deal with the asymmetry of the path from a source node to a destination node which affects either the delivery of the original packets, or the paths taken by acknowledgments, or both. Furthermore, the problem of hidden nodes requires a more careful analysis in the case of asymmetric links. MAC layer and routing protocols for ad hoc networks with asymmetric links require a rigorous performance analysis. Analytical models are usually unable to provide even approximate solutions to questions such as end-to-end delay, packet loss ratio, throughput, etc. Traditional simulation techniques for large-scale wireless networks require vast amounts of storage and computing cycles rarely available on single computing systems. In our search for an effective solution to study the performance of wireless networks we investigate the time-parallel simulation. Time-parallel simulation has received significant attention in the past. The advantages, as well as, the theoretical and practical limitations of time-parallel simulation have been extensively researched for many applications when the complexity of the models involved severely limits the applicability of analytical studies and is unfeasible with traditional simulation techniques. Our goal is to study the behavior of large systems consisting of possibly thousands of nodes over extended periods of time and obtain results efficiently, and time-parallel simulation enables us to achieve this objective. We conclude that MAC layer and routing protocols capable of using asymmetric links are more complex than traditional ones, but can improve the connectivity, and provide better performance. We are confident that approximate results for various performance metrics of wireless networks obtained using time-parallel simulation are sufficiently accurate and able to provide the necessary insight into the inner workings of the protocols

“Southern by the grace of God:” religion and race in Hollywood’s South since the 1960s

This thesis examines the presentation and functions of Protestant Christianity in cinematic depictions of the American South, focusing primarily on Hollywood’s civil rights narratives, from the 1960s to the present. It argues that religion is an understudied signifier of the South on film, used to define the region’s presumed exceptionalism. Rooted in close textual analysis and primary research into the production and reception of over a dozen films, the thesis deploys methodologies drawn from history, film, literary, and cultural studies. It questions why scholars have seldom acknowledged the role of religion in popular, especially cinematic, constructions of the South, before providing detailed case studies of specific films that utilize southern religiosity to negotiate regional and national anxieties around race, class, and gender. Though scholars have recognized the intersections of race, class, and gender evident in the media’s construction of southern white segregationist, this thesis contends that religion adds further interrogative value to existing analyses of civil rights cinema in particular, and of Hollywood’s representations of southern race, class, and gender identities more generally. The thesis argues that the perceived religious zealotry of many segregationists supports Hollywood’s recurring presentation of the South as an irrational region, where religiosity and rabid racism cloud all judgment. The perceived ‘southernization’ of America through the culture wars of the late twentieth-century encouraged many Americans to reconsider the legacy of the civil rights era, a movement that was being concurrently reshaped in the popular imagination by Hollywood dramas such as Mississippi Burning, A Time to Kill, and Ghosts of Mississippi among many other films. Examining the presentation of both white and black Christianity in these films, the thesis illuminates how cinema has routinely fabricated a simplistic binary of good and evil that pits a noble, yet reductive and static, religious African American community against zealous white trash and fundamentalists operating on the margins of society. So often to blame for the incendiary racial violence that marks such movies, these white villains are often associated with fundamentalism, in both rhetoric and actions, enabling filmmakers to offer a clear culprit for the South’s, and therefore the nation’s, legacy of racial intolerance and violence

Digital control networks for virtual creatures

Robot control systems evolved with genetic algorithms traditionally take the form of floating-point neural network models. This thesis proposes that digital control systems, such as quantised neural networks and logical networks, may also be used for the task of robot control. The inspiration for this is the observation that the dynamics of discrete networks may contain cyclic attractors which generate rhythmic behaviour, and that rhythmic behaviour underlies the central pattern generators which drive lowlevel motor activity in the biological world. To investigate this a series of experiments were carried out in a simulated physically realistic 3D world. The performance of evolved controllers was evaluated on two well known control tasks—pole balancing, and locomotion of evolved morphologies. The performance of evolved digital controllers was compared to evolved floating-point neural networks. The results show that the digital implementations are competitive with floating-point designs on both of the benchmark problems. In addition, the first reported evolution from scratch of a biped walker is presented, demonstrating that when all parameters are left open to evolutionary optimisation complex behaviour can result from simple components

Multi-Agent Systems

A multi-agent system (MAS) is a system composed of multiple interacting intelligent agents. Multi-agent systems can be used to solve problems which are difficult or impossible for an individual agent or monolithic system to solve. Agent systems are open and extensible systems that allow for the deployment of autonomous and proactive software components. Multi-agent systems have been brought up and used in several application domains