Dissertations / Theses on the topic 'Design Agent'

Design patterns document a field's systematic knowledge derived from experiences. Despite the vast body of work in the field of multi-agent systems (MAS), design patterns for MAS are not popular among software practitioners. As MAS have features that are widely considered as key to engineering complex distributed applications, for example in manufacturing, robotics, ecommerce, traffic control and coordination, science simulations, it is important to provide a clear overview of existing patterns to make this knowledge accessible. To that end, a systematic literature review was performed covering the main publication venues of the field since 1998, resulting in 206 patterns. The study shows that (1) there is a lack of a standard template for documenting design patterns for MAS, which hampers the use of patterns by practitioners, (2) associations between patterns are poorly described, which results in a lack of overview of the pattern space, (3) patterns for MAS have been used for a variety of application domains, which underpins their high potential for practitioners, and (4) classifications of design patterns for MAS are bounded to specific pattern catalogs, a more holistic view on the pattern space is missing. From the study, a number of guidelines is outlined that are important for future work on design patterns for MAS and their adoption in practice.

As software requirements grow increasingly complex, the need to connect to and re-use existing, tested software, grows with it. Open systems, such as the Internet, aid this process by connecting together software services provided by a range of organisations, and the distributed nature of the system allows the services to be regularly updated and improved. Applications can be deployed within the open systems that opportunistically attempt to make use of the best functionality available at any one time. Agent-based systems have been proposed as an ideal way to implement such applications, due to their flexibility and distributed control. However, a balance must be kept between acting opportunistically and ensuring that each application operates to the standards demanded by the application requirements. Determining whether an application will perform to its requirements necessitates justifying the design decisions made in creating it. Our goal is to provide application developers with the means to create justified designs for opportunistic applications. The main contribution of this thesis is a software engineering methodology, agent interaction analysis, based on a set of independently valuable techniques we have developed. The first of these is a novel approach to modelling applications as being instantiated by a set of agent interactions, allowing such applications to be described with minimal restrictions on their implemented structure. Second, we provide a technique, based on design patterns, for comparing mechanisms for instantiating parts of multi-agent system. Finally, we provide an approach to more detailed analysis and comparison of coordination mechanisms.

Design decision making increasingly involves the participation of multiple agents which bring into the design process multiple, and often conflicting, needs, knowledge, and goals. To the human agents (experts from the same or different domains, clients, users, stakeholders) one should add artificial agents (computational models and tools more generally) that play an important part in the process. Design research has considered the issue of distributed decision making mainly through the concepts of cooperation and collaboration. The present thesis argues that coordination is a more apposite concept for capturing the social distributed character of design. The concept of coordination places emphasis on issues of interdependency, complexity and distribution and enables us to understand design at a systemic/organisational level, without making assumptions about agents' commitment to a common goal, or their disposition towards cooperation or conflict. Additionally, coordination is used to capture the generative, creative aspects of distributed design decision making. The study explores and establishes the meaning of coordination through experimentation with computational models and simulations. The very process of building these models is a vehicle for exploring key hypotheses and assumptions, and developing a coherent theoretical construction. Overall, the thesis identifies the key dimensions of coordination that are typical to the domain of design, and employs them to develop a framework (a theory) for understanding multi-agent design as a generative social process. The dimensions identified are learning, decentralised control and co-evolution. A model of coordination developed using the paradigm of distributed learning control is used as a way to establish the precise meaning of these dimensions. Based on insights from the experimentation, the concept of coordination is further refined in order to propose an organisational (complexity-informed) perspective of multi-agent design. According to this perspective, the relationship between agents, their goals, and the design variables they manipulate, is at the same time a product of the design process, but also a constraint over individual agents. Coordination is then defined as a dynamic process towards a scheme of organisation that entails the emergence of collective design solutions.

Debugging multi-agent systems, which are concurrent, distributed, and consist of complex components is difficult, yet crucial. The development of these complex systems is supported by agent-oriented software engineering methodologies which utilise agents as the central design metaphor. The systems that are developed are inherently complex since the components of these systems may interact in flexible and sophisticated ways and traditional debugging techniques are not appropriate. Despite this, very little effort has been applied to developing appropriate debugging tools and techniques. Debugging multi-agent systems without good debugging tools is highly impractical and without suitable debugging support developing and maintaining multi-agent systems will be more difficult than it need be. In this thesis we propose that the debugging process can be supported by following an agent-oriented design methodology, and then using the developed design artifacts in the debugging phase. We propose a domain independent debugging framework which comprises the developed processes and components that are necessary in using design artifacts as debugging artifacts. Our approach is to take a non-formal design artifact, such as an AUML protocol design, and encode it in a machine interpretable manner such that the design can be used as a model of correct system behaviour. These models are used by a run-time debugging system to compare observed behaviour against specified behaviour. We provide details for transforming two design artifact types into equivalent debugging artifacts and show how these can be used to detect bugs. During a debugging episode in which a bug has been identified our debugging approach can provide detailed information about the possible reason for the bug occurring. To determine if this information was useful in helping to debug programs we undertook a thorough empirical study and identified that use of the debugging tool translated to an improvement in debugging performance. We conclude that the debugging techniques developed in this thesis provide effective debugging support for multi-agent systems and by having an extensible framework new design artifacts can be explored and as translations are developed they can be added to the debugging system.

Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, March 2001.
Thesis advisors, Michael Zyda, John E. Hiles. Includes bibliographical references (p. 81-82). Also available online.

Ultrasound contrast agents, consisting of gas bubbles coated with a surfactant or polymer shell, offer benefits in a range of diagnostic and therapeutic applications. However, their behaviour both in vitro and in vivo is by no means fully understood and there remains considerable scope for increasing their effectiveness. The aim of the work described in this thesis is to improve the characterisation of existing contrast agents and to determine how future agents might be designed in order to optimise their performance. Previous theoretical and experimental work relating to both contrast agents and free gas bubbles will be reviewed. This will be followed by an assessment of the validity of the assumptions underlying existing models for contrast agents. In particular, examination will be made of: the modelling of the material coating the contrast agent particles (CAPs), the influence of blood cells upon CAP dynamics and multiple scattering of ultrasound in CAP suspensions. The results from a combination of computer simulations and experimental testing will be used to derive a new, generalised model for CAP behaviour. The model will be used to carry out a sensitivity analysis in order to identify the most significant factors controlling CAP behaviour. Based on these findings, a number of new designs will be developed, with the aim of enhancing CAP detectability at low insonation pressures. The designs will be evaluated in terms of their performance, based on the results of experiments using scale models. Finally, an assessment of the areas for future work will be made.

This research complements and combines market microstructure theory and mechanism design to optimize the market structure of financial markets systematically. We develop an agent-based model featuring near-zero-intelligence traders operating in a call market with a wide range of trading rules governing the determination of prices, which orders are executed as well as a range of parameters regarding market intervention by market makers and the presence of informed traders. The market structure which generates the best market performance is determined by applying the search technique Population-based Incremental Learning, guided by a number of performance measures, including maximizing trading volume or price, minimizing bid-ask spread or return volatility. We investigate the credibility of our model by observing the trading behavior of near-zero-intelligence traders with stylized facts in real markets. Based on computer simulations, we conform that the model is capable to reproduce some of the most important stylized facts found in financial markets. Thereafter, we investigate the best found market structure using both single-objective optimization and multi-objective optimization techniques. Our results suggest that the best-found combination of trading rules used to enhance trading volume may not be applied to achieve other objectives, such as reducing bid-ask spread. The results of single-objective optimization experiments show that significantly large tick sizes appear in the best market structures in most cases, except for the case of maximizing trading volume. The tick size is always correlated with the selection of multi-price rules. Though there is no particular combination of priority rule and multiprice rule achieving the best market performance, the time priority rule and the closest multi-price rule are the most frequently obtained rules. The level of market transparency and the extend of market maker intervention show ambiguous results as their representative parameter values change in a wide range. We also nd that the results of multi-objective optimization experiments are much similar to those obtained in the single-objective optimization experiments, except for the market transparency represented by the fraction of informed trader, which shows a clear trend in the multi-objective optimization. Using the results obtained from this research we can derive recommendations for exchanges and regulators on establishing the optimal market structure; for securities issuers on choosing the best exchange for their listing; and for investors on choosing the most suitable exchange for trading.

Agent-based technology is playing an increasingly important role in today’s economy. Usually a multi-agent system is needed to model an economic system such as a market system, in which heterogeneous trading agents interact with each other autonomously. Two questions often need to be answered regarding such systems: 1) How to design an interacting mechanism that facilitates efficient resource allocation among usually self-interested trading agents? 2) How to design an effective strategy in some specific market mechanisms for an agent to maximise its economic returns? For automated market systems, auction is the most popular mechanism to solve resource allocation problems among their participants. However, auction comes in hundreds of different formats, in which some are better than others in terms of not only the allocative efficiency but also other properties e.g., whether it generates high revenue for the auctioneer, whether it induces stable behaviour of the bidders. In addition, different strategies result in very different performance under the same auction rules. With this background, we are inevitably intrigued to investigate auction mechanism and strategy designs for agent-based economics. The international Trading Agent Competition (TAC) Ad Auction (AA) competition provides a very useful platform to develop and test agent strategies in Generalised Second Price auction (GSP). AstonTAC, the runner-up of TAC AA 2009, is a successful advertiser agent designed for GSP-based keyword auction. In particular, AstonTAC generates adaptive bid prices according to the Market-based Value Per Click and selects a set of keyword queries with highest expected profit to bid on to maximise its expected profit under the limit of conversion capacity. Through evaluation experiments, we show that AstonTAC performs well and stably not only in the competition but also across a broad range of environments. The TAC CAT tournament provides an environment for investigating the optimal design of mechanisms for double auction markets. AstonCAT-Plus is the post-tournament version of the specialist developed for CAT 2010. In our experiments, AstonCAT-Plus not only outperforms most specialist agents designed by other institutions but also achieves high allocative efficiencies, transaction success rates and average trader profits. Moreover, we reveal some insights of the CAT: 1) successful markets should maintain a stable and high market share of intra-marginal traders; 2) a specialist’s performance is dependent on the distribution of trading strategies. However, typical double auction models assume trading agents have a fixed trading direction of either buy or sell. With this limitation they cannot directly reflect the fact that traders in financial markets (the most popular application of double auction) decide their trading directions dynamically. To address this issue, we introduce the Bi-directional Double Auction (BDA) market which is populated by two-way traders. Experiments are conducted under both dynamic and static settings of the continuous BDA market. We find that the allocative efficiency of a continuous BDA market mainly comes from rational selection of trading directions. Furthermore, we introduce a high-performance Kernel trading strategy in the BDA market which uses kernel probability density estimator built on historical transaction data to decide optimal order prices. Kernel trading strategy outperforms some popular intelligent double auction trading strategies including ZIP, GD and RE in the continuous BDA market by making the highest profit in static games and obtaining the best wealth in dynamic games.

This project is a site-specific ethnographic study of a culture around a community water tank that serves as a value-driven piece of architecture and has become an inconspicuous tourist attraction in the city of Växjö due to its peculiar acoustic property. At the onset, I draw parallels between an ancient underground temple called the Hypogeum located in Malta, where the physical dimensions of the space similarly shaped sensorial experiences in more nuanced ways than conventional architecture of its time. The core of my work here has three explorative angles. One, where I embark on interdisciplinary research approaches, to conduct field studies and investigate ways to empirically test how the physical properties of spaces shape cognitive impressions. A crucial need to express spirituality within an academic framework is proposed and a method of non-intentional design (NID) is introduced as my driving process for the study. Two, as a digital story, I conduct interviews and make the culture of this space visible to the public through an instagram account called #echoingawareness. And three, I present some of my experience building this slow and steady relation with the local municipality with a proposal to provide space on the urban planning table for bottom-up approaches where voices from such sacred spaces can be made more inclusive. I hope this could be a useful resource as a transdisciplinary study for future planning of urban architecture and design.

A scenario where multiple entities interact with a common environment to achieve individual and common goals either co-operatively or competitively can be classified as a Multi-Agent System. In this thesis, we concentrate on the situations where the agents exhibit selfish, competitive and strategic behaviour, giving rise to interesting game theoretic and optimization problems. From a computational point of view, the presence of multiple agents introduces strategic and temporal issues, apart from enhancing the difficulty of optimization. We study the following natural mathematical models of such multi-agent problems faced in practice: a) combinatorial optimization problems with multi-agent submodular cost functions, b) combinatorial auctions with partially public valuations and c) online vertex-weighted bipartite matching and single bid budgeted allocations. We provide approximation algorithms, online algorithms and hardness of approximation results for these problems.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A presente pesquisa tem por objetivo entender as visões projetuais que acompa-nham os livros de bolso pertencentes ao gênero de literatura infanto-juvenil no cenário nacional. Interessa-nos contribuir com a compreensão acerca de quais são as visões projetuais aplicadas aos livros de bolso e de como o design participa da mediação da leitura de um público inscrito na contemporaneidade. Temos por pressuposto que o design é agente mediador da leitura e que, consequentemente, o projeto gráfico característico das edições de bolso participa de forma ativa na construção de hábitos de leitura e na conversão de significados para o leitor. Como recorte de pesquisa, elegemos livros de bolso presentes no 16 Feira Nacional do Livro Infantil e Juvenil, ocorrida entre 28 de maio e 8 de junho de 2014 na cidade do Rio de Janeiro. Na pesquisa de campo, entramos em contato com as diferentes maneiras como os leitores se relacionam com essas edições. A partir do levantamento dos livros de bolso de literatura infanto-juvenil, realizamos a análise gráfica do design de nove deles, editados pela L&PM, BestBolso e Zahar, o que nos permitiu enxergar as visões projetuais dessas edições. Constatamos que nos livros de bolso publicados por essas editoras, é predominante a manutenção de parâmetros relacionados às caracte-rísticas históricas e formais deste objeto. Por fim, destacamos a importância do papel mediador do design na aproximação e formação de novos leitores e apontamos as potencialidades ainda não exploradas pelos projetos gráficos dos livros de bolso nacionais de literatura infanto-juvenil.
The present research aims to understand the project visions that accompany pocket books that belong to the gender of children and adolescent literature in the national scene. It interests us to contribute to the understanding of which are the project visions applied to pocket books and how Design participates in the mediation of reading of the contemporary public. We assume that Design is the mediator of reading and, consequently, that the graphic project of pocket editions participates actively in the reading habits and the creation of meaning for the reader. We have selected as a research focus the pocket books that were found in the 16th National Book Fair of Children and Adolescents, which occurred between May 28th and June 8th, 2014 in the city of Rio de Janeiro. In the field research, we have encountered the different ways in which readers relate to these editions. From the survey of children and adolescent books, we have made a graphic analysis of the design of nine of them, which were edited by L&PM, BestBolso and Zahar and allowed us to see the project visions of these editions. We have concluded that in the pocket books published by these publishing houses the maintenance of the parameters related to the historical and formal characteristics of this object is predominant. Finally, we highlight the importance of mediating role of Design on the approach and formation of new readers, pointing out the potentialities yet not explored by the graphic projects of national pocket books of children and adolescent literature.

The security and resiliency of electric power supply to serve critical facilities are of high importance in todayâ s world. Instead of building large electric power grids and high capacity transmission lines, an intelligent microgrid (or smart grid) can be considered as a promising power supply alternative. In recent years, multi-agent systems have been proposed to provide intelligent energy control and management systems in microgrids. Multi-agent systems offer their inherent benefits of flexibility, extensibility, autonomy, reduced maintenance and more. The implementation of a control network based on multi-agent systems that is capable of making intelligent decisions on behalf of the user has become an area of intense research. Many previous works have proposed multi-agent system architectures that deal with buying and selling of energy within a microgrid and algorithms for auction systems. The others proposed frameworks for multi-agent systems that could be further developed for real life control of microgrid systems. However, most proposed methods ignore the process of sharing energy resources among multiple distinct sets of prioritized loads. It is important to study a scenario that emphasizes on supporting critical loads during outages based on the userâ s preferences and limited capacity. The situation becomes further appealing when an excess DER capacity after supplying critical loads is allocated to support non-critical loads that belong to multiple users. The previous works also ignore the study of dynamic interactions between the agents and the physical systems. It is important to study the interaction and time delay when an agent issues a control signal to control a physical device in a microgrid and when the command is executed. Agents must be able to respond to the information sensed from the external environment quickly enough to manage the microgrid in a timely fashion. The ability of agents to disconnect the microgrid during emergencies should also be studied. These issues are identified as knowledge gaps that are of focus in this thesis. The objective of this research is to design, develop and implement a multi-agent system that enables real-time management of a microgrid. These include securing critical loads and supporting non-critical loads belonging to various owners with the distributed energy resource that has limited capacity during outages. The system under study consists of physical (microgrid) and cyber elements (multi-agent system). The cyber part or the multi-agent system is of primary focus of this work. The microgrid simulation has been implemented in Matlab/Simulink. It is a simplified distribution circuit that consists of one distributed energy resources (DER), loads and the main grid power supply. For the multi-agent system implementation, various open source agent building toolkits are compared to identify the most suitable agent toolkit for implementation in the proposed multi-agent system. The agent architecture is then designed by dividing overall goal of the system into several smaller tasks and assigning them to each agent. The implementation of multi-agent system was completed by identifying Roles (Role Modeling) and Responsibilities (Social and Domain Responsibilities) of agents in the system, and modeling the Knowledge (Facts), rules and ontology for the agents. Finally, both microgrid simulation and multi-agent system are connected together via TCP/IP using external java programming and a third party TCP server in the Matlab/Simulink environment. In summary, the multi-agent system is designed, developed and implemented in several simulation test cases. It is expected that this work will provide an insight into the design and development of a multi-agent system, as well as serving as a basis for practical implementation of an agent-based technology in a microgrid environment. Furthermore, the work also contributes to new design schemes to increase multi-agent systemâ s intelligence. In particular, these include control algorithms for intelligently managing the limited supply from a DER during emergencies to secure critical loads, and at the same time supporting non-critical loads when the users need the most.
Master of Science

In this thesis, we propose a novel approach to model the diffusion of residential PV systems. For this purpose, we use an agent-based model where agents are the families living in the area of interest. The case study is the Emilia-Romagna Regional Energy plan, which aims to increase the produc- tion of electricity from renewable energy. So, we study the microdata from the Survey on Household Income and Wealth (SHIW) provided by Bank of Italy in order to obtain the characteristics of families living in Emilia-Romagna. These data have allowed us to artificial generate families and reproduce the socio-economic aspects of the region. The families generated by means of a software are placed on the virtual world by associating them with the buildings. These buildings are acquired by analysing the vector data of regional buildings made available by the region. Each year, the model determines the level of diffusion by simulating the installed capacity. The adoption behaviour is influenced by social interactions, household’s economic situation, the environmental benefits arising from the adoption and the payback period of the investment.

This research aims at developing a different kind of virtual world that is dynamically designed and implemented as needed. Currently, most virtual world designs are considered static. Similar to the physical world, these worlds are pre-defined prior to their use. The resultant environments serve certain purposes but do not take into consideration possible changes to the purposes during their use, changes which often occur when the occupants interact with the environments and with each other. Virtual worlds as networked environments can be flexibly configured and programmed. This flexibility makes it possible to consider virtual world designs in terms of dynamics and autonomy, reflecting the changing needs of different moments. To achieve dynamic designs of virtual worlds, this study applies a computational approach using rational design agents. A Generative Design Agent (GDA) model is developed that specifies computational processes for reasoning and designing in virtual worlds. The GDAs serve as personal design agents to the virtual world occupants. Design formalisms for virtual worlds are also addressed. The design component of a GDA is supported by the application of a generative design grammar. On one hand, generative design grammars serve as the generative force to be applied by the GDAs for virtual world design automation. On the other hand, each grammar defines coherent stylistic characterisations shared by the virtual world designs it generates. The technical outcomes of the research consist of the GDA model and a generative design grammar framework. The framework provides guidelines and strategies to designers for developing generative design grammars that produce different design languages for virtual worlds, rather than predefine every detail of all possible virtual world designs. GDAs monitor the virtual worlds and the various activities that occur in the worlds, interpret the occupants’ needs in the virtual worlds and the state of the worlds based on these observations, hypothesise design goals in order to satisfy these needs, and finally apply generative design grammars to provide virtual world designs for the moment, or initiate other actions in the worlds, according to the current design goals, on behalf of the occupants. The development of the GDA model and the generative design grammar framework provides new perspectives for understanding and developing virtual worlds. The GDA model challenges the conventional way that virtual worlds are designed and implemented, and this leads to dynamic designs of virtual worlds. The generative design grammar framework provides a computational approach to formally defining design languages for virtual worlds.

Doctor of Philosophy (PhD)
This research aims at developing a different kind of virtual world that is dynamically designed and implemented as needed. Currently, most virtual world designs are considered static. Similar to the physical world, these worlds are pre-defined prior to their use. The resultant environments serve certain purposes but do not take into consideration possible changes to the purposes during their use, changes which often occur when the occupants interact with the environments and with each other. Virtual worlds as networked environments can be flexibly configured and programmed. This flexibility makes it possible to consider virtual world designs in terms of dynamics and autonomy, reflecting the changing needs of different moments. To achieve dynamic designs of virtual worlds, this study applies a computational approach using rational design agents. A Generative Design Agent (GDA) model is developed that specifies computational processes for reasoning and designing in virtual worlds. The GDAs serve as personal design agents to the virtual world occupants. Design formalisms for virtual worlds are also addressed. The design component of a GDA is supported by the application of a generative design grammar. On one hand, generative design grammars serve as the generative force to be applied by the GDAs for virtual world design automation. On the other hand, each grammar defines coherent stylistic characterisations shared by the virtual world designs it generates. The technical outcomes of the research consist of the GDA model and a generative design grammar framework. The framework provides guidelines and strategies to designers for developing generative design grammars that produce different design languages for virtual worlds, rather than predefine every detail of all possible virtual world designs. GDAs monitor the virtual worlds and the various activities that occur in the worlds, interpret the occupants’ needs in the virtual worlds and the state of the worlds based on these observations, hypothesise design goals in order to satisfy these needs, and finally apply generative design grammars to provide virtual world designs for the moment, or initiate other actions in the worlds, according to the current design goals, on behalf of the occupants. The development of the GDA model and the generative design grammar framework provides new perspectives for understanding and developing virtual worlds. The GDA model challenges the conventional way that virtual worlds are designed and implemented, and this leads to dynamic designs of virtual worlds. The generative design grammar framework provides a computational approach to formally defining design languages for virtual worlds.

El presente trabajo aborda la especificación, diseño e implementación de organizaciones abiertas de agentes. Se defiende que tales organizaciones pueden ser diseñadas e implementadas de manera efectiva como organizaciones electrónicas institucionalizadas (instituciones electrónicas) compuestas de un gran número de agentes heterogéneos (tanto humanos como software) adoptando diversos roles e interactuando por medio de ilocuciones. Adicionalmente postulamos que el diseño y la implementación de instituciones electrónicas deben ser guiadas por una metodología bien fundamentada. Es por ello que proponemos una especificación formal de instituciones electrónicas que fundamente su diseño, análisis e implementación
A continuación presentamos un modelo computacional que emerge de y fielmente captura la formalización resultante de la noción de institución electrónica. Nuestro modelo computacional se define y explota sobre la base de la noción de mediación para fundamentar la construcción de infraestructuras para instituciones electrónicas. Así, proponemos construir instituciones electrónicas a partir de agentes institucionales ---agentes en los que la institución delega sus servicios e interagentes ---agentes software autónomos dedicados a mediar la interacción entre cada agente y la sociedad de agentes en el marco de una institución electrónica. De esta manera las instituciones electrónicas son concebidas computacionalmente como instituciones electrónicas mediadas por agentes, ya que tanto los servicios institucionales como las interacciones son mediados por agentes.
Ilustramos la construcción práctica de instituciones electrónicas mediadas por agentes describiendo el desarrollo de una casa electrónica de subastas inspirada en las lonjas de pescado tradicionales donde agentes heterogéneos (humanos y software) pueden comerciar.
Finalmente presentamos la evolución de la casa de subastas electrónicas a una plataforma para la experimentación en escenarios de subasta. Mostramos cómo en tales escenarios agentes compradores y vendedores de diferentes complejidades participan en subastas definidas de acuerdo a unas condiciones de mercado estandarizadas, siendo evaluados en función de su rendimiento en el mercado. Desde nuestro punto de vista tales escenarios competitivos constituyen interesantes y ricos dominios en los que estudiar cuestiones generales relacionadas con arquitecturas de agentes que comercian y, más específicamente, con sus comportamientos estratégicos.
This thesis focuses on the specification, design and implementation of open agent organisations. We argue that open agent organisations can be effectively designed and implemented as institutionalised electronic organisations (electronic institutions) composed of a vast amount of heterogeneous (human and software) agents playing different roles and interacting by means of speech acts. Then we take the view that the design and development of electronic institutions must be guided by a principled methodology. For this purpose we propose a formal specification of electronic institutions that founds their design, analysis and development.
Next we present a computational model that arises from and fully captures the resulting formalisation of electronic institution. Our computational model strongly relies on and exploits the notion of mediation for founding the realisation of electronic institutions' infrastructures. Thus we propose how to fully realise an electronic institution based on institutional agents ---the agents to which the institution delegates its services--- and interagents ---autonomous software agents devoted to mediating the interaction between each agent and the agent society in the framework of an electronic institution. Therefore electronic institutions are computationally conceived as agent-mediated electronic institutions since both institutional services and interactions are mediated by agents.
We illustrate the practical realisation of agent-mediated electronic institutions by describing the development of an electronic auction house inspired by the age old institution of the fish market where heterogeneous (software and human) agents may trade.
Lastly we present the evolution of the electronic auction house into a test-bed for experimenting with auction-based trading scenarios. We show how in these scenarios trading agents of arbitrary complexity participate in auctions under a collection of standardised market conditions and are evaluated according to their actual market performance. We argue that such competitive situations constitute convenient problem domains in which to study issues related with trading agent architectures in general and agent-based trading strategies in particular.

Software agents and multi-agent systems (MAS) have grown into a very active area of research and commercial development activity. There are many current emerging real-world applications spanning multitude of diverse domains. In the context of agents, ontology has been widely recognised for their significant benefits to interoperability, reusability, and both development and operational aspects of agent systems and applications. Ontology-based multi-agent systems (OBMAS) exploit these advantages in providing intelligent and semantically aware applications. In addressing the lack of support for ontology in existing methodologies for multi-agent development, this thesis proposes a design methodology for the building of such intelligent multi-agent applications called MOMA. This alternative approach focuses on the development of ontology as the driving force of the development process. By allowing the domain and characteristics of utilisation and experimentation to be dictated through ontology, researchers and domain experts can specify the agent application without any knowledge of agent design and lower level programming. Through the use of a structured ontology model and the use of integrated tools, this approach contributes towards the building of semantically aware intelligent applications for use by researchers and domain experts. MOMA is evaluated through case studies in two different domains: financial services and e-Health.

Video games have become more and more advanced, yet their artificial intelli-gence components are often a source of criticism. Even though academic AI hascome very far, it is rarely seen in video games due to computational complexity.Video games usually use most of their computation time on graphics and physics,and since they require quick response times, the AI is left with scarce resources touse advanced techniques. This project examines the use of case-based reasoningand multi-agent cooperation to improve the existing AI in a commercial videogame. The game is called Heroes of Newerth and is developed by S2Games. Wefocus on making group decisions in this real-time environment which is partiallyobservable. We also use case-based reasoning techniques to improve agents’ de-cisions. Our goal is to implement an agent with these properties, which is bothmore challenging and fun to play against.

This thesis presents a feature-based design system called MADSfm (MultiAgent Design System for manufacturability), which allows the creation of 21/2D mechanical components, performs on the fly manufacturability analysis and even solves common problems automatically. The system uses the multiagent paradigm at a feature level to create a new type of active product model. Indeed, each feature inside the product model is embodied by an autonomous agent capable of communicating with its peers, building an image of its world, assessing its fitness in this world and modifying its own geometry to guarantee its manufacturability. The model therefore becomes a community of motivated pro-active agents able to carry out simple tasks on behalf on the user. The underlying activity inside the agent community representing the model leads to a global emergent behaviour in the system that ensures component manufacturability. In turn the emergent behaviour allows a reduction of the amount of global component knowledge needed to perform manufacturability analysis. Most activity can take place locally for each individual feature making the approach robust and a good candidate for parallelisation and distribution. The agent-driven approach to feature-based design and manufacturability analysis ensures robust manufacturable designs with a shorter lead time bringing substantial cost savings.

There is an increasing need for multi-agent systems to operate under decentralised control regimes that support openness (individual components can enter and leave at will) and enable components representing distinct stakeholders with different aims and objectives to interact effectively. To this end, this thesis explores issues associated with using techniques from Game Theory and Mechanism Design to organise and analyse such systems. In particular, emphasis is given to distributed mechanisms in which there is distributed allocation (no single centre determines the allocation of the resources or the tasks) and distributed information (agents require information privately known by other agents in order to determine their own valuation or cost). Such mechanisms are important because, in comparison to their centralised counterparts, they are robust to a single-point failure, the computational burden can be potentially shared amongst many agents, and there is a reduction in bottlenecks since not all communication need pass through a single point. As a result, distributed mechanisms are better suited to many types of multi-agent application. To provide a grounding for the mechanisms we develop, the thesis contains a running example of a multi-sensor network scenario. In these systems, distributed allocation mechanisms are desirable since they are robust and reduce bottlenecks in the communication system. Furthermore, we show that distributed information naturally arises by deriving an information-theoretic valuation function. This scenario also gives rise to two additional requirements that are addressed within this thesis: (i) constrained capacity, whereby suppliers can only provide a limited amount of goods or services at any given time and (ii) uncertainty in task completion, whereby sensors potentially fail after they have been assigned tasks. Specifically, we focus on the \ac{vcg} mechanisms and investigate ways of extending it so as to address the requirements that arise within distributed setting in general and sensor networks. In particular, we choose the VCG as our point of departure since it is a mechanism that is efficient, individually rational and incentive compatible. Unfortunately, it is brittle in the sense that it does not conserve these desirable properties when considering the requirements that we outlined above. Therefore, we develop novel mechanisms that do. In more detail, the first part of this thesis considers two distributed allocation mechanisms --- a simultaneous auction environment and \ac{cda}. In the former, bidders place sealed bids in a number of selling auctions which are concurrently offering items. This results in a distributed allocation whereby the winner at each auction is determined by the seller conducting it. For this case, we derive the optimal strategy of the bidders using a game-theoretic approach. In the \acs{cda}, buyers and sellers, respectively, submit bids and asks continuously and the market clears when a bid is higher than an ask; meaning that the allocation is again determined in a distributed way. Furthermore, CDAs are known to yield close to efficient allocations, under certain conditions, even when utilising very simple strategies. However, in our case, we need to modify their format in order to deal with the requirement of constrained capacity. In both of these mechanisms, we study the system's loss in efficiency that ensues from distributing the allocation and find that it is $\frac{1}{e}$ in the simultaneous auction case and upto $35 \%$ in the continuous double auction case. The second part of this thesis is concerned with designing mechanisms when agents have distributed information within the system. Such settings are more general than those more traditionally studied in that they encompass the fact that agents can potentially change their valuation or cost upon knowing a signal about the system (which they have not observed) that was hitherto unknown to them. Specifically, we first show that interdependent valuations arise naturally within a sensor network when we develop an information-theoretic valuation function. To account for this, we significantly extend the VCG mechanism in order to deal with these interdependent valuations. We then go on to develop a mechanism that can deal with uncertainty in task allocation. In both of these cases, our mechanisms are shown to be efficient, individually rational and incentive compatible. Moreover, their computational properties are studied and efficient algorithms are designed (based on linear and dynamic programming) in order to speed up the computation of the allocation problem which is generally $\mathcal{NP}$-hard.

Au cours des dernières années, les systèmes multi-agents (SMA) sont devenus l'une des technologies les plus prometteuses pour la conception et le développement des systèmes énergétiques intelligents nommés aussi Smart-Grid. Cependant, l'utilisation de la technologie d'agent dans l'ingénierie des systèmes pour modéliser, contrôler et simuler les comportements des systèmes énergétiques, pose encore de nombreux défis : méthodologiques ; techniques (liés à l’ingénierie des SMA en général) ; de standardisation et d’exploration architecturale (liés au domaine de Smart Grid en particulier). Cette thèse propose un cadre architectural conforme à la norme ISO 42010, contenant l'ensemble des conventions, principes et pratiques pour la description des architectures multi-agents établies dans le domaine des Smart-Grids, comme une solution adéquate pour résoudre les problèmes mentionnés ci-dessus. Le cadre architectural s'appuie sur l'Ingénierie Dirigée par les Modèles (IDM) pour résoudre les problèmes techniques et méthodologiques. Ce cadre est supporté par une méthodologie qui adhère à l’utilisation des standards d’agents et des standards énergétiques dans les phases d’analyse et de conception des SMAs. Le cadre se base sur une approche d'évaluation des styles d'architecture multi-agents pour sélectionner le style le plus approprié pour répondre à des exigences non fonctionnelles liées à un domaine d'application spécifique. Par ailleurs, un langage de modélisation indépendant des plateformes d'agents a été proposé permettant la modélisation des SMAs et l’analyse des modèles développés pour vérifier leur conformité au style d’architecture SMA sélectionné. L’approche a été prototypée dans un environnement d’Ingénierie Dirigée par les Modèles et évalué sur un cas d’application représentatif du domaine des Smarts-Grids
In recent years, multi-agent systems (MAS) have emerged as one of the most promising technologies for the design and development of intelligent energy systems, also known as Smart-Grid. However, the use of agent technology in systems engineering to model, control and simulate energy system’ behavior still faces many challenges: methodological; technical (generally related to MAS engineering); standardization and architectural exploration (specifically related to the Smart Grid domain). This thesis proposes an architectural framework in accordance with ISO 42010, containing all the conventions, principles and practices for the description of multi-agent architectures established in the field of Smart-Grids, as an adequate solution to solve the problems mentioned above. The architectural framework relies on Model Driven Engineering (MDE) to solve technical and methodological problems. This framework is supported by a methodology that adheres the use of agent and energy standards in the MAS analysis and design phases. The framework is based on a multi-agent architecture style evaluation approach to select the most appropriate style to meet non-functional requirements related to a specific application domain. In addition, a platform-independent agent modeling language was proposed to model MASs and analyze the developed models to verify their compliance with the selected MAS architecture style. The approach was prototyped in a Model Driven Engineering environment and evaluated on a representative application case from the Smarts-Grids domain

Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Jeff Shamma; Committee Member: Eric Feron; Committee Member: Magnus Egerstedt. Part of the SMARTech Electronic Thesis and Dissertation Collection.

"Design is a very complicated and ill-defined problem solving activity. Routine parametric design is a more restricted and well-defined version of design problems. Even this restricted version requires many different kinds of expert knowledge and the ability to perform a variety of tasks. One approach to solving this restricted version is to use Single Function Agents (SiFAs), each of which can perform a very specialized task, from a single point of view. The ability to represent expertise with different points of view is very important in design. These different points of view usually cause conflicts among agents, and these conflicts need to be resolved in order for the design process to be successful. Therefore, agents need to be capable of detecting and resolving these conflicts. This thesis presents a model of conflicts and negotiations in the SiFA framework. Some extensions to the present state of the SiFA paradigm are introduced. A hierarchy of possible conflicts is proposed and the steps of the negotiation process are discussed. The ability of agents to negotiation in order to resolve conflicts makes SiFA-based design systems more versatile, less brittle, and easier to construct and maintain. Also, the extended SiFA paradigm, where agents have negotiation capabilities leads to many interesting directions for further research. "

La co-construction et la réutilisation de modèles font l'objet de plusieurs travaux dans le domaine de la simulation. Cependant, dans le domaine plus spécifique de la Simulation Orientée Agent (SOA), nous pouvons constater un manque sur ces deux points malgré un besoin fort de la part des thématiciens. La co-construction est essentielle pour optimiser la mise en commun du savoir de différents experts, mais nous faisons souvent face à des divergences de points de vue. Les méthodologies existantes pour la co-construction en SOA ne permettent qu'un faible niveau de collaboration entre thématiciens durant la phase initiale de modélisation, ainsi qu'entre les des thématiciens avec les modélisateurs ou les modélisateurs-informaticiens... Pour faciliter cette co-construction, nous proposons de suivre une méthodologie de conception favorisant cette collaboration. La réutilisation de modèle octroie un gain de temps significatif, une amélioration du modèle et l'apport de nouvelle connaissance. Les méthodologies en SOA dans ce domaine existent. Cependant, dans le spectre de réutilisation, elles sont souvent limitées au niveau du modèle complet ou de l'agent avec l'impossibilité de "descendre" plus bas. L'expérience de EDMMAS, un cas concret d'un modèle issu de trois réutilisations successives, nous a permis de constater une nouvelle complexité qui découle de la démultiplication des comportements des agents et crée un décalage conséquent entre le modèle opérationnel et le modèle conceptuel. Notre objectif est de promouvoir la réutilisation aussi bien des modèles, que des agents et de leurs comportements.Pour répondre à ces questionnements, nous proposons dans ce manuscrit une manière de codifier et d'intégrer la connaissance provenant de disciplines différentes dans le modèle, tout en utilisant des modules "composables" qui facilitent la réutilisation. Nous proposons (i) une nouvelle architecture Agent (aMVC), appliquée dans un cadre multidynamique (DOM), avec l'appui (ii) d'une approche méthodologique (MMC) basée sur la décomposition et réutilisation des comportements. Cet ensemble de propositions, (i) et (ii), permet de conduire un projet pluridisciplinaire de SOA avec un grand nombre d'acteurs, facilitant la co-construction des modèles grâce à l'instauration de nouvelles synergies entre les différents acteurs participant à la modélisation. Les concepteurs pourront travailler de manière autonome sur leur dynamique et la plateforme fera l'intégration de ces dernières en assurant la cohésion et la robustesse du système. Nos contributions offrent la capacité de créer les briques élémentaires du système de manière indépendante, de les associer et de les combiner pour former des agents, selon des dynamiques conformément à l'approche DOM. Elles permettent ainsi de comparer la logique selon différentes possibilités pour une même dynamique et d'ouvrir la perspective d'étudier un grand nombre d'alternatives de modélisation d'un même système complexe, et de les analyser ensuite à une échelle très fine.

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
FUNDAÇÃO NACIONAL DE SAÚDE
O design do livro é uma arte invisível? Depende do leitor. Mas como este leitor é considerado pelos designers de livros? Esta questão é o ponto de partida deste estudo, que busca investigar como o designer pode participar do processo de formação de escritores e leitores, compreendendo a inserção do Design, enquanto campo de vocação interdisciplinar, em projetos em que há a predominância do hibridismo, da mescla de vozes e da mescla de identidades.Sabendo que os designers de livro servem a três clientes: autor, leitor e editor, é verificado que apenas autor e editor interferem diretamente no trabalho do designer, enquanto este profissional considera o leitor apenas por uma noção pré-concebida. Desta forma, questiona-se a ausência do leitor nos projetos de design do livro,ao mesmo tempo em que se propõe a noção de Design da Leitura.O estudo considera as teorias que tratam da recepção e mediação da leitura, como em Chartier, e utiliza-se de um exercício etnográfico sobre os encontros presenciais do Projeto de Escolarização dos Agentes de Saúde voltado para o agentes Guarani das aldeias de Itaxi, Araponga, Sapukai e Rio Pequeno, na região de Angra dos Reis e Paraty. A partir da observação das práticas da leitura do grupo Guarani são levantadas questões para pensar uma abordagem que contemple as características destes leitores. Portanto, ao reconhecer a importância do leitor e das mediações, o Design da Leitura contempla também o letramento, ao tentar contribuir tanto para a alfabetização como para a formação das práticas sociais de leitura e escrita.
Is Book Design an invisible Art? How is the reader considered by book designers? These questions are the starting point for this study, which aims at investigating how can a designer contribute to the process of forming new writers and readers. Design is here approached as an interdisciplinary vocational area where hybrid projects occur; encompassing different voices and identities. We work on the assumption that book designers consider three kinds of clients - the author, reader and publisher - and that only author and publisher have traditionally interfered in the designer´s work more directly, while the reader exists more as a pre-conceived notion. By and large, the reader has been disregarded by book designers. We, then, try to propose what we call a Design for Reading or Reading Design. We consider theories that deal with reception and mediation in the reading process. We use theoretians like Roger Chartier and apply them to an Ethnographic exercise carried out at the Schooling Project with Guarani Health Agents in the Native Brazilian Villages of Itaxi, Araponga, Sapukai and Rio Pequeno in the Angra dos Reis and Paraty Regions. By observing the reading process by the Guarani Agents, we raise questions on how to encompass the specific profile of such a reader in the visual project, thereby recognizing the importance of the reader and mediation in the Reading Design. We also consider some aspects of literacy in order to contribute to new reading and writing. social processes.

This thesis focuses on the development of a system in which a team of heterogeneous mobile robots can cooperate to perform a wide range of tasks. In order that a group of heterogeneous robots can cooperate among them, one of the most important parts to develop is the creation of an architecture which gives support for the cooperation. This architecture is developed by means of embedding agents and interfacing agent code with native low-level code. It also addresses the implementation of resource sharing among the whole group of robots, that is, the robots can borrow capabilities from each-other.
In order to validate this architecture, some cooperative applications have been implemented. The first one is an application where a group of robots must cooperate in order to safely navigate through an unknown environment. One robot with camera calculates the optical flow values from the images, and from these values calculates the "time to contact" values. This information is shared among the team so that any robot can navigate without colliding with the obstacles.
The second cooperative application consists of enabling the team of heterogeneous robots to create a certain formation and navigate maintaining this formation. The application consists of two parts or stages. The first one is the creation of the formation, where a robot with the camera can detect where the rest of the robots are in the environment and indicates to them which is their initial position in the formation. In the second stage the robots must be able to navigate through an environment following the path that the robot with the laser indicates. Due to the odometry errors of the robots, the camera of one of the robots is used so that robots which lose their correct position in the formation can re-align themselves.
Finally, in an attempt to facilitate access to the robots of the team and to the information that their accessories provide, a system for the teleoperation of the team has been implemented. This system can be used for teaching robotics or to facilitate the tasks of programming and debugging in the research tasks.

Intelligent agents are rapidly gaining popularity in our increasingly networked world since their emergence at the beginning of the last decade as a promising design and implementation solution for future applications. They provide information monitoring, searching filtering, and decision aiding that help people focus on the information that is most pertinent to them in a particular context. One central class of agents is personal assistants. They can be distinguished from ordinary agents by the fact that they work at the interface level rather than the application level. They model their owners' interests, provide services to them, and act on their behalf when required. Their domains of application include Internet information retrieval, E-commerce, telecommunication, and network management. This thesis aims to present a general model of personal assistants using agent technology. The proposed model aims to efficiently provide all necessary functionality regardless of the application. Our system architecture consists of three distinct agents. They are the User Interface Agent, Information Management Agent, and Personal Agent. They communicate with each other, with the human user, and with other agents using Agent Communication Language in order to provide services to their owners. The model was applied in the Virtual Team Collaboration project as an agent that helps the user managing his Agenda, managing the team, scheduling meetings, and acting on the user's behalf. The thesis work show also how can we use our model of personal assistant in E-commerce.

The initial stages of reliability-based design optimization involve the formulation of objective functions and constraints, and building a model to estimate the reliability of the design with quantified uncertainties. However, even experienced hands often overlook important objective functions and constraints that affect the design. In addition, uncertainty reduction measures, such as tests and redesign, are often not considered in reliability calculations during the initial stages. This research considers two areas that concern the design of engineering systems: 1) the trade-off of the effect of a test and post-test redesign on reliability and cost and 2) the search for multiple candidate designs as insurance against unforeseen faults in some designs. In this research, a methodology was developed to estimate the effect of a single future test and post-test redesign on reliability and cost. The methodology uses assumed distributions of computational and experimental errors with re-design rules to simulate alternative future test and redesign outcomes to form a probabilistic estimate of the reliability and cost for a given design. Further, it was explored how modeling a future test and redesign provides a company an opportunity to balance development costs versus performance by simultaneously designing the design and the post-test redesign rules during the initial design stage.The second area of this research considers the use of dynamic local surrogates, or surrogate-based agents, to locate multiple candidate designs. Surrogate-based global optimization algorithms often require search in multiple candidate regions of design space, expending most of the computation needed to define multiple alternate designs. Thus, focusing on solely locating the best design may be wasteful. We extended adaptive sampling surrogate techniques to locate multiple optima by building local surrogates in sub-regions of the design space to identify optima. The efficiency of this method was studied, and the method was compared to other surrogate-based optimization methods that aim to locate the global optimum using two two-dimensional test functions, a six-dimensional test function, and a five-dimensional engineering example.

Un système multi-agent (SMA) est un système dans lequel plusieurs agents opèrent et interagissent. Chaque agent a la responsabilité d’exécuter des tâches. Cependant, chaque agent, pour diverses raisons, peut rencontrer des problèmes pendant l’exécution de ses tâches ; ce qui peut induire un disfonctionnement du SMA. Cependant, le SMA doit être en mesure de détecter les sources de problèms (d’erreurs) afin de les contrôler et ainsi continuer son exécution correctement. Un tel SMA est appelé un SMA tolérant aux fautes. Il existe deux types de sources d’erreurs pour un agent : les erreurs causées par son environnment et les erreurs dûes à sa programmation. Dans la littérature, il existe plusieurs techniques qui traitent des erreurs de programmation au niveau des agents. Cependant, ces techniques ne traitent pas des erreurs causées par l’environnement de l’agent. Tout d’abord, nous distinguons entre l’environnment d’un agent et l’environnement du SMA. L’environnement d’un agent représente toutes les composantes matérielles ou logicielles que l’agent ne peut contrôler mais avec lesquelles il interagit. Cependant, l’environnment du SMA représente toutes les composantes que le système ne contrôle pas mais avec lesquelles il interagit. Ainsi, le SMA peut contrôler certaines des composantes avec lesquelles un agent interagit. Ainsi, une composante peut appartenir à l’environnement d’un agent et ne pas appartenir à l’environnement du système. Dans ce travail, nous présentons une méthodologie de conception de SMA tolérants aux fautes, nommée FATMAS, qui permet au concepteur du SMA de détecter et de corriger, si possible, les erreurs causées par les environnements des agents. Cette méthodologie permettra ainsi de délimiter la frontière du SMA de son environnement avec lequel il interagit. La frontière du SMA est déterminée par les différentes composantes (matérielles ou logicielles) que le système contrôle. Ainsi, le SMA, à l’intérieur de sa frontière, peut corriger les erreurs provenant de ses composantes. Cependant, le SMA n’a aucun contrôle sur toutes les composantes opérant dans son environnement. La méthodologie, que nous proposons, doit couvrir les trois premières phases d’un développement logiciel qui sont l’analyse, la conception et l’implémentation tout en intégrant, dans son processus de développement, une technique permettant au concepteur du système de délimiter la frontière du SMA et ainsi détecter les sources d’erreurs et les contrôler afin que le système multi-agent soit tolérant aux fautes (SMATF). Cependant, les méthodologies de conception de SMA, référencées dans la littérature, n’intègrent pas une telle technique. FATMAS offre au concepteur du SMATF quatre modèles pour décrire et développer le SMA ainsi qu’une technique de réorganisation du système qui lui permet de détecter et de contrôler ses sources d’erreurs, et ainsi définir la frontière du SMA. Chaque modèle est associé à un micro processus qui guide le concepteur lors du développement du modèle. FATMAS offre aussi un macro-processus, qui définit le cycle de développement de la méthodologie. FATMAS se base sur un développement itératif pour identifier et déterminer les tâches à ajouter au système afin de contrôler des sources d’erreurs. À chaque itération, le concepteur évalue, selon une fonction de coût/bénéfice s’il est opportun d’ajouter de nouvelles tâches de contrôle au système. Le premier modèle est le modèle de tâches-environnement. Il est développé lors de la phase d’analyse. Il identifie les différentes tâches que les agents doivent exécuter, leurs préconditions et leurs ressources. Ce modèle permet d’identifier différentes sources de problèmes qui peuvent causer un disfonctionnement du système. Le deuxième modèle est le modèle d’agents. Il est développé lors de la phase de conception. Il décrit les agents, leurs relations, et spécifie pour chaque agent les ressources auxquelles il a le droit d’accéder. Chaque agent exécutera un ensemble de tâches identifiées dans le modèle de tâches-environnement. Le troisième modèle est le modèle d’interaction d’agents. Il est développé lors de la phase de conception. Il décrit les échanges de messages entre les agents. Le quatrième modèle est le modèle d’implémentation. Il est développé lors de la phase d’implémentation. Il décrit l’infrastructure matérielle sur laquelle le SMA va opérer ainsi que l’environnement de développement du SMA. La méthodologie inclut aussi une technique de réorganisation. Cette technique permet de délimiter la frontière du SMA et contrôler, si possible, ses sources d’erreurs. Cette technique doit intégrer trois techniques nécessaires à la conception d’un système tolérant aux fautes : une technique de prévention d’erreurs, une technique de recouvrement d’erreurs, et une technique de tolérance aux fautes. La technique de prévention d’erreurs permet de délimiter la frontière du SMA. La technique de recouvrement d’erreurs permet de proposer une architecture du SMA pour détecter les erreurs. La technique de tolérance aux fautes permet de définir une procédure de réplication d’agents et de tâches dans le SMA pour que le SMA soit tolérant aux fautes. Cette dernière technique, à l’inverse des techniques de tolérance aux fautes existantes, réplique les tâches et les agents et non seulement les agents. Elle permet ainsi de réduire la complexité du système en diminuant le nombre d’agents à répliquer. Résumé iv De même, un agent peut ne pas être en erreur mais la composante matérielle sur laquelle il est exécuté peut ne plus être fonctionnelle. Ce qui constitue une source d’erreurs pour le SMA. Il faudrait alors que le SMA continue à s’exécuter correctement malgrè le disfonctionnement d’une composante. FATMAS fournit alors un support au concepteur du système pour tenir compte de ce type d’erreurs soit en contrôlant les composantes matérielles, soit en proposant une distribution possible des agents sur les composantes matérielles disponibles pour que le disfonctionnement d’une composante matérielle n’affecte pas le fonctionnement du SMA. FATMAS permet d’identifier des sources d’erreurs lors de la phase de conception du système. Cependant, elle ne traite pas des sources d’erreurs de programmation. Ainsi, la technique de réorganization proposée dans ce travail sera validée par rapport aux sources d’erreurs identifiées lors de la phase de conception et provenant de la frontière du SMA. Nous démontrerons formellement que, si une erreur provient d’une composante que le SMA contrôle, le SMA devrait être opérationnel. Cependant, FATMAS ne certifie pas que le futur système sera toujours opérationnel car elle ne traîte pas des erreurs de programmation ou des erreurs causées par son environnement.
A multi-agent system (MAS) consists of several agents interacting together. In a MAS, each agent performs several tasks. However, each agent is prone to individual failures so that it can no longer perform its tasks. This can lead the MAS to a failure. Ideally, the MAS should be able to identify the possible sources of failures and try to overcome them in order to continue operating correctly ; we say that it should be fault-tolerant. There are two kinds of sources of failures to an agent : errors originating from the environment with which the agents interacts, and programming exceptions. There are several works on fault-tolerant systems which deals with programming exceptions. However, these techniques does not allow the MAS to identify errors originating from an agent’s environment. In this thesis, we propose a design methodology, called FATMAS, which allows a MAS designer to identify errors originating from agents’ environments. Doing so, the designer can determine the sources of failures it could be able to control and those it could not. Hence, it can determine the errors it can prevent and those it cannot. Consequently, this allows the designer to determine the system’s boundary from its environment. The system boundary is the area within which the decision-taking process of the MAS has power to make things happen, or prevent them from happening.We distinguish between the system’s environment and an agent’s environment. An agent’s environment is characterized by the components (hardware or software) that the agent does not control. However, the system may control some of the agent’s environment components. Consequently, some of the agent’s environment components may not be a part of the system’s environment. The development of a fault-tolerant MAS (FTMAS) requires the use of a methodology to design FTMAS and of a reorganization technique that will allow the MAS designer to identify and control, if possible, different sources of system failure. However, current MAS design methodologies do not integrate such a technique. FATMAS provides four models used to design and implement the target system and a reorganization technique to assist the designer in identifying and controlling different sources of system’s failures. FATMAS also provides a macro process which covers the entire life cycle of the system development as well as several micro processes that guide the designer when developing each model. The macro-process is based on an iterative approach based on a cost/benefit evaluation to help the designer to decide whether to go from one iteration to another. The methodology has three phases : analysis, design, and implementation. The analysis phase develops the task-environment model. This model identifies the different tasks the agents will perform, their resources, and their preconditions. It identifies several possible sources of system failures. The design phase develops the agent model and the agent interaction model. The agent model describes the agents and their resources. Each agent performs several tasks identified in the task-environment model. The agent interaction model describes the messages exchange between agents. The implementation phase develops the implementation model, and allows an automatic code generation of Java agents. The implementation model describes the infrastructure upon which the MAS will operate and the development environment to be used when developing the MAS. The reorganization technique includes three techniques required to design a fault-tolerant system : a fault-prevention technique, a fault-recovery technique, and a fault-tolerance technique. The fault-prevention technique assists the designer in delimiting the system’s boundary. The fault-recovery technique proposes a MAS architecture allowing it to detect failures. The fault-tolerance technique is based on agent and task redundancy. Contrary to existing fault-tolerance techniques, this technique replicates tasks and agents and not only agents. Thus, it minimizes the system complexity by minimizing the number of agents operating in the system. Furthermore, FATMAS helps the designer to deal with possible physical component failures, on which the MAS will operate. It proposes a way to either control these components or to distribute the agents on these components in such a way that if a component is in failure, then the MAS could continue operating properly. The FATMAS methodology presented in this dissertation assists a designer, in its development process, to build fault-tolerant systems. It has the following main contributions : 1. it allows to identify different sources of system failure ; 2. it proposes to introduce new tasks in a MAS to control the identified sources of failures ; 3. it proposes a mechanism which automatically determines which tasks (agents) should be replicated and in which other agents ; 4. it reduces the system complexity by minimizing the replication of agents ; Abstract vii 5. it proposes a MAS reorganization technique which is embedded within the designed MAS and assists the designer to determine the system’s boundary. It proposes a MAS architecture to detect and recover from failures originating from the system boundary. Moreover, it proposes a way to distribute agents on the physical components so that the MAS could continue operating properly in case of a component failure. This could make the MAS more robust to fault prone environments. FATMAS alows to determine different sources of failures of a MAS. The MAS controls the sources of failures situated in its boundary. It does not control the sources of failures situated in its environments. Consequently, the reorganization technique proposed in this dissertation will be proven valid only in the case where the sources of failures are controlled by the MAS. However, it cannot be proven that the future system is fault-tolerant since faults originating from the environment or from coding are not dealt with.

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores
In this thesis it is presented an approach to the problem of layout design for a manufacturing system, which is an important part of its design stage, given that it has influence in the system efficiency and, therefore, in its output rate and fault handling capabilities. The presented approach is based on a Genetic Algorithm (GA) that, by using information provided by the the user through an ontology file, and by using algorithms from graph-theory, designs the layout of a manufacturing system. The instances of the ontology represent manufacturing resources and their characteristics that, when they are being used by the algorithm, are encoded in chromosomes and in their genes. The algorithm begins with a number of chromosomes with low fitness which, with the directed evolution provided by the algorithm, that is restricted by the control parameters that might be tunned by the user, improve with the passing of the new generations. It is considered that the fittest solution is the one that connects, in order, all the resources required by the manufacturing plan, described in the ontology, without the occurrence of overlaps when the layout is constructed. The configuration presented by the transport system that handles parts and materials, in the selected layout, is only dependent on the available resources and on the fitness function used by the GA, being that the last cannot be changed by the user. This approach differs from others by positioning simultaneously all the components of the manufacturing system and not only workstations or transport system. The solution is directed to evolvable assembly systems, purpose for which it was implemented inside an agent, so it can be integrated in a Multiagent System (MAS) to be used in the control of a manufacturing system with minimal changes. Keywords: layout design, manufacturing system, multiagent system, ontology, genetic algorithm.

AN ABSTRACT OF THE THESIS OF PRASHANTHI BANALA, for the Master of Science degree in ELECTRICAL AND COMPUTER ENGINEERING, presented on 31 October 2011, at Southern Illinois University Carbondale. TITLE: OUTPUT FEEDBACK H-inf CONTROL DESIGN FOR MULTI-AGENT SYSTEMS MAJOR PROFESSOR: Dr. Farzad Pourboghrat In this thesis, the design of distributed control for identical multi-agent systems is considered based on the optimization of H-inf cost function. Identical dynamically coupled but interacting systems (agents) are considered where control action of each agent is based on relative output measurement of their neighboring agents and a subset of their own output. The agents communicate with each other to achieve a common goal. A distributed dynamic output feedback control strategy that satisfies H-inf performance for multi-agent systems is developed and corresponding H-inf performance region is analyzed. An example illustrates the necessary and sufficient condition for dynamic output feedback controller synthesis to obtain desired H-inf performance.

The usage of conversational agents in domestic spaces is increasing every year and with this ethical issues that we have not anticipated will arise, both because these relationships are human-like and not human-like.This thesis shows that ethically responsible relations- hips between humans and conversational agents in private contexts and domestic environments are much more than conversational design. This project is not primarily focussing on designing dialogues, words, and voices but takes a closer look at the qualities and values these relationships are based on. It is looking at how agents are staged, using design fiction as a methodlogy and medium to raise questions around the impacts of these relati- onships. Furthermore, it is also pointing out some of the possible unintended consequences that could occur if these agents are staged, like personaswith human-like features or if technology goes in between human-human relationships.After multiple design explorations and realizing how complex human-agent and human-human re-lationships are, I realized that the best way to make an impact was not to provide solutions on how ethically responsible relationships between humans and conversational agents should look like. Instead, I have created a set of fictional design ar- tifacts in different future contexts. They aim to point out what designers who design for these relations- hips need to tweak and pay attention to to create more ethically responsible futures.As I created these design fictions, I aimed to find a good balance between humor, provocation, and abstraction to leave room for people‘s imagination. In addition, I am hoping to provoke enough for my audience to feel triggered to raise even more re- levant questions and point out further opportunities for other designers to build on my work.Finally, a fictional design organization was created, which I called “A(i)activists“. I see this as a space where the design fiction can live on and a great medium to communicate the project vision and mis- sion and create a small place for ongoing debates and input from a diverse audience.

This thesis makes a number of contributions to the theory of approximation algorithm design for multi-agent systems. In particular, we focus on two research directions. The first direction is to generalize the classical framework of combinatorial optimization to the submodular setting, where we assume that each agent has a submodular cost function. We show hardness results from both the information-theoretic and computational aspects for several fundamental optimization problems in the submodular setting, and provide matching approximation algorithms for most of them. The second direction is to introduce game-theoretic issues to approximation algorithm design. Towards this direction, we study the application of approximation algorithms in the theory of truthful mechanism design. We study both the standard objectives of revenue and social welfare, by designing efficient algorithms that satisfy the requirement of truthfulness and guarantee approximate optimality.

碩士
國立交通大學
資訊工程系
88
As the Internet grows rapidly, we can get many information in the Internet. So, it’s more important to find the information that we want. Search engines may help us to find the relative information, it’s still user’s responsibility to actively use it. In this thesis, we design a tool, called Personal Information Agent (PIA), that can actively push information to users. In this thesis, we design a Personal Information Agent framework, it help us to develop the Personal Information Agent application by calling these objects or functions. We also implement a personal information application based on the framework to demonstrate the correctness and feasibility of our system architecture.