787 resultados para multi-agent system


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This paper seeks to show which impacts there are of the combined use of different modal for the coffee’s outflow. Nowadays is used, almost exclusively, the roadway to transport. How-ever, for this product with low added value, the types of transports best suited, in the litera-ture, are the railway and waterway. For this, is describe the development and spread of coffee throughout Brazil. Subsequently, is calculate the current cost of transporting two producing regions (Minas Gerais and Rondônia), using for that information about the freight, the social cost, and the level of losses along the way. After that is projected costs if utilizes the multi-modal model, when considering the same cost parameters used for the current model. Here-after, an analysis is made of the obtained cost, speed, consistency, capacity, availability and frequency of each transport model. Therefore, note that the multi-modal system is more ef-ficient and economical than current, based on transport by road

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Pós-graduação em Ciência da Computação - IBILCE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The principal aim of this study is to examine attitudes and values, through questionnaires, among students and teachers in the last grade of primary school (grade 8) regarding issues related to authoritarianism, democracy, human rights, children rights, conflict resolution and legislation in Bosnia and Herzegovina. A second aim is to explore and analyze the role of the international community in the democratization and education processes in the light of globalization in this country through secondary sources of data, site visits and observations. Analysis of the student sample reveals suspicion towards democracy, especially when democracy was associated with politics and politicians. When the issue of democracy was de-contextualized from Bosnia and Herzegovina realities in the questionnaire, students showed more positive attitudes towards it. Students generally agreed with very strong authoritarian statements. High achieving students were more democratic, more socially responsible, more tolerant regarding attitudes towards religion, race and disabilities, and less authoritarian compared to low achievers. High achievers felt that they had influence over daily events, and were positive towards social and civil engagement. High achievers viewed politics negatively, but had high scores on the democracy scale. High achievers also agreed to a larger extent that it is acceptable to break the law. The more authoritarian students were somewhat more prone to respond that it is not acceptable to break the law. The major findings from the teacher sample show that teachers who agreed with non-peaceful mediation, and had a non-forgiving and rigid approach to interpersonal conflicts, also agreed with strong authoritarian statements and were less democratic. In general, teachers valued students who behave respectfully, have a good upbringing and are obedient. They were very concerned about the general status of education in society, which they felt was becoming marginalized. Teachers were not happy with the overloaded curricula and they showed an interest in more knowledge and skills to help children with traumatic war experiences. When asked about positive reforms, teachers were highly critical of, and dissatisfied with, the educational situation. Bosnia and Herzegovina is undergoing a transition from a state-planned economy and one party system to a market economy and a multi party system. During this transition, the country has become more involved in the globalization process than ever. Today the country is a semi-protectorate where international authorities intervene when necessary. The International community is attempting to introduce western democracy and some of the many complexities in this process are discussed in this study. Globalization processes imply contradictory demands and pressures on the education system. On one hand, economic liberalization has affected education policies —a closer alignment between education and economic competitiveness. On the other hand, there is a political and ideological globalization process underlying the importance of human rights, and the inclusiveness of education for all children. Students and teachers are caught between two opposing ideals — competition and cooperation.

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Agent Communication Languages (ACLs) have been developed to provide a way for agents to communicate with each other supporting cooperation in Multi-Agent Systems. In the past few years many ACLs have been proposed for Multi-Agent Systems, such as KQML and FIPA-ACL. The goal of these languages is to support high-level, human like communication among agents, exploiting Knowledge Level features rather than symbol level ones. Adopting these ACLs, and mainly the FIPA-ACL specifications, many agent platforms and prototypes have been developed. Despite these efforts, an important issue in the research on ACLs is still open and concerns how these languages should deal (at the Knowledge Level) with possible failures of agents. Indeed, the notion of Knowledge Level cannot be straightforwardly extended to a distributed framework such as MASs, because problems concerning communication and concurrency may arise when several Knowledge Level agents interact (for example deadlock or starvation). The main contribution of this Thesis is the design and the implementation of NOWHERE, a platform to support Knowledge Level Agents on the Web. NOWHERE exploits an advanced Agent Communication Language, FT-ACL, which provides high-level fault-tolerant communication primitives and satisfies a set of well defined Knowledge Level programming requirements. NOWHERE is well integrated with current technologies, for example providing full integration for Web services. Supporting different middleware used to send messages, it can be adapted to various scenarios. In this Thesis we present the design and the implementation of the architecture, together with a discussion of the most interesting details and a comparison with other emerging agent platforms. We also present several case studies where we discuss the benefits of programming agents using the NOWHERE architecture, comparing the results with other solutions. Finally, the complete source code of the basic examples can be found in appendix.

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The sustained demand for faster,more powerful chips has beenmet by the availability of chip manufacturing processes allowing for the integration of increasing numbers of computation units onto a single die. The resulting outcome, especially in the embedded domain, has often been called SYSTEM-ON-CHIP (SOC) or MULTI-PROCESSOR SYSTEM-ON-CHIP (MPSOC). MPSoC design brings to the foreground a large number of challenges, one of the most prominent of which is the design of the chip interconnection. With a number of on-chip blocks presently ranging in the tens, and quickly approaching the hundreds, the novel issue of how to best provide on-chip communication resources is clearly felt. NETWORKS-ON-CHIPS (NOCS) are the most comprehensive and scalable answer to this design concern. By bringing large-scale networking concepts to the on-chip domain, they guarantee a structured answer to present and future communication requirements. The point-to-point connection and packet switching paradigms they involve are also of great help in minimizing wiring overhead and physical routing issues. However, as with any technology of recent inception, NoC design is still an evolving discipline. Several main areas of interest require deep investigation for NoCs to become viable solutions: • The design of the NoC architecture needs to strike the best tradeoff among performance, features and the tight area and power constraints of the on-chip domain. • Simulation and verification infrastructure must be put in place to explore, validate and optimize the NoC performance. • NoCs offer a huge design space, thanks to their extreme customizability in terms of topology and architectural parameters. Design tools are needed to prune this space and pick the best solutions. • Even more so given their global, distributed nature, it is essential to evaluate the physical implementation of NoCs to evaluate their suitability for next-generation designs and their area and power costs. This dissertation focuses on all of the above points, by describing a NoC architectural implementation called ×pipes; a NoC simulation environment within a cycle-accurate MPSoC emulator called MPARM; a NoC design flow consisting of a front-end tool for optimal NoC instantiation, called SunFloor, and a set of back-end facilities for the study of NoC physical implementations. This dissertation proves the viability of NoCs for current and upcoming designs, by outlining their advantages (alongwith a fewtradeoffs) and by providing a full NoC implementation framework. It also presents some examples of additional extensions of NoCs, allowing e.g. for increased fault tolerance, and outlines where NoCsmay find further application scenarios, such as in stacked chips.

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While the use of distributed intelligence has been incrementally spreading in the design of a great number of intelligent systems, the field of Artificial Intelligence in Real Time Strategy games has remained mostly a centralized environment. Despite turn-based games have attained AIs of world-class level, the fast paced nature of RTS games has proven to be a significant obstacle to the quality of its AIs. Chapter 1 introduces RTS games describing their characteristics, mechanics and elements. Chapter 2 introduces Multi-Agent Systems and the use of the Beliefs-Desires-Intentions abstraction, analysing the possibilities given by self-computing properties. In Chapter 3 the current state of AI development in RTS games is analyzed highlighting the struggles of the gaming industry to produce valuable. The focus on improving multiplayer experience has impacted gravely on the quality of the AIs thus leaving them with serious flaws that impair their ability to challenge and entertain players. Chapter 4 explores different aspects of AI development for RTS, evaluating the potential strengths and weaknesses of an agent-based approach and analysing which aspects can benefit the most against centralized AIs. Chapter 5 describes a generic agent-based framework for RTS games where every game entity becomes an agent, each of which having its own knowledge and set of goals. Different aspects of the game, like economy, exploration and warfare are also analysed, and some agent-based solutions are outlined. The possible exploitation of self-computing properties to efficiently organize the agents activity is then inspected. Chapter 6 presents the design and implementation of an AI for an existing Open Source game in beta development stage: 0 a.d., an historical RTS game on ancient warfare which features a modern graphical engine and evolved mechanics. The entities in the conceptual framework are implemented in a new agent-based platform seamlessly nested inside the existing game engine, called ABot, widely described in Chapters 7, 8 and 9. Chapter 10 and 11 include the design and realization of a new agent based language useful for defining behavioural modules for the agents in ABot, paving the way for a wider spectrum of contributors. Chapter 12 concludes the work analysing the outcome of tests meant to evaluate strategies, realism and pure performance, finally drawing conclusions and future works in Chapter 13.

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Il sempre crescente numero di applicazioni di reti di sensori, robot cooperanti e formazioni di veicoli, ha fatto sì che le problematiche legate al coordinamento di sistemi multi-agente (MAS) diventassero tra le più studiate nell’ambito della teoria dei controlli. Esistono numerosi approcci per affrontare il problema, spesso profondamente diversi tra loro. La strategia studiata in questa tesi è basata sulla Teoria del Consenso, che ha una natura distribuita e completamente leader-less; inoltre il contenuto informativo scambiato tra gli agenti è ridotto al minimo. I primi 3 capitoli introducono ed analizzano le leggi di interazione (Protocolli di Consenso) che permettono di coordinare un Network di sistemi dinamici. Nel capitolo 4 si pensa all'applicazione della teoria al problema del "loitering" circolare di più robot volanti attorno ad un obiettivo in movimento. Si sviluppa a tale scopo una simulazione in ambiente Matlab/Simulink, che genera le traiettorie di riferimento di raggio e centro impostabili, a partire da qualunque posizione iniziale degli agenti. Tale simulazione è stata utilizzata presso il “Center for Research on Complex Automated Systems” (CASY-DEI Università di Bologna) per implementare il loitering di una rete di quadrirotori "CrazyFlie". I risultati ed il setup di laboratorio sono riportati nel capitolo 5. Sviluppi futuri si concentreranno su algoritmi locali che permettano agli agenti di evitare collisioni durante i transitori: il controllo di collision-avoidance dovrà essere completamente indipendente da quello di consenso, per non snaturare il protocollo di Consenso stesso.

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Humans and animals face decision tasks in an uncertain multi-agent environment where an agent's strategy may change in time due to the co-adaptation of others strategies. The neuronal substrate and the computational algorithms underlying such adaptive decision making, however, is largely unknown. We propose a population coding model of spiking neurons with a policy gradient procedure that successfully acquires optimal strategies for classical game-theoretical tasks. The suggested population reinforcement learning reproduces data from human behavioral experiments for the blackjack and the inspector game. It performs optimally according to a pure (deterministic) and mixed (stochastic) Nash equilibrium, respectively. In contrast, temporal-difference(TD)-learning, covariance-learning, and basic reinforcement learning fail to perform optimally for the stochastic strategy. Spike-based population reinforcement learning, shown to follow the stochastic reward gradient, is therefore a viable candidate to explain automated decision learning of a Nash equilibrium in two-player games.

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In this critical analysis of sociological studies of the political subsystem in Yugoslavia since the fall of communism Mr. Ilic examined the work of the majority of leading researchers of politics in the country between 1990 and 1996. Where the question of continuity was important, he also looked at previous research by the writers in question. His aim was to demonstrate the overall extent of existing research and at the same time to identify its limits and the social conditions which defined it. Particular areas examined included the problems of defining basic concepts and selecting the theoretically most relevant indicators; the sources of data including the types of authentic materials exploited; problems of research work (contacts, field control, etc.); problems of analysisl and finally the problems arising from different relations with the people who commission the research. In the first stage of the research, looking at methods of defining key terms, special attention was paid to the analysis of the most frequently used terms such as democracy, totalitarianism, the political left and right, and populism. Numerous weaknesses were noted in the analytic application of these terms. In studies of the possibilities of creating a democratic political system in Serbia and its possible forms (democracy of the majority or consensual democracy), the profound social division of Serbian society was neglected. The left-right distinction tends to be identified with the government-opposition relation, in the way of practical politics. The idea of populism was used to pass responsibility for the policy of war from the manipulator to the manipulated, while the concept of totalitarianism is used in a rather old-fashioned way, with echoes of the cold war. In general, the terminology used in the majority of recent research on the political subsystem in Yugoslavia is characterised by a special ideological style and by practical political material, rather than by developed theoretical effort. The second section of analysis considered the wider theoretical background of the research and focused on studies of the processes of transformation and transition in Yugoslav society, particularly the work of Mladen Lazic and Silvano Bolcic, who he sees as representing the most important and influential contemporary Yugoslav sociologists. Here Mr. Ilic showed that the meaning of empirical data is closely connected with the stratification schemes towards which they are oriented, so that the same data can have different meanings in shown through different schemes. He went on to show the observed theoretical frames in the context of wider ideological understanding of the authors' ideas and research. Here the emphasis was on the formalistic character of such notions as command economy and command work which were used in analysing the functioning and the collapse of communist society, although Mr. Ilic passed favourable judgement on the Lazic's critique of political over-determination in its various attempts to explain the disintegration of the communist political (sub)system. The next stage of the analysis was devoted to the problem of empirical identification of the observed phenomena. Here again the notions of the political left and right were of key importance. He sees two specific problems in using these notion in talking about Yugoslavia, the first being that the process of transition in the FR Yugoslavia has hardly begun. The communist government has in effect remained in power continuously since 1945, despite the introduction of a multi-party system in 1990. The process of privatisation of public property was interrupted at a very early stage and the results of this are evident on the structural level in the continuous weakening of the social status of the middle class and on the political level because the social structure and dominant form of property direct the majority of votes towards to communists in power. This has been combined with strong chauvinist confusion associated with the wars in Croatia and Bosnia, and these ideas were incorporated by all the relevant Yugoslav political parties, making it more difficult to differentiate between them empirically. In this context he quotes the situation of the stream of political scientists who emerged in the Faculty of Political Science in Belgrade. During the time of the one-party regime, this faculty functioned as ideological support for official communist policy and its teachers were unable to develop views which differed from the official line, but rather treated all contrasting ideas in the same way, neglecting their differences. Following the introduction of a multi-party system, these authors changed their idea of a public enemy, but still retained an undifferentiated and theoretically undeveloped approach to the issue of the identification of political ideas. The fourth section of the work looked at problems of explanation in studying the political subsystem and the attempts at an adequate causal explanation of the triumph of Slobodan Milosevic's communists at four subsequent elections was identified as the key methodological problem. The main problem Mr. Ilic isolated here was the neglect of structural factors in explaining the voters' choice. He then went on to look at the way empirical evidence is collected and studied, pointing out many mistakes in planning and determining the samples used in surveys as well as in the scientifically incorrect use of results. He found these weaknesses particularly noticeable in the works of representatives of the so-called nationalistic orientation in Yugoslav sociology of politics, and he pointed out the practical political abuses which these methodological weaknesses made possible. He also identified similar types of mistakes in research by Serbian political parties made on the basis of party documentation and using methods of content analysis. He found various none-sided applications of survey data and looked at attempts to apply other sources of data (statistics, official party documents, various research results). Mr. Ilic concluded that there are two main sets of characteristics in modern Yugoslav sociological studies of political subsystems. There are a considerable number of surveys with ambitious aspirations to explain political phenomena, but at the same time there is a clear lack of a developed sociological theory of political (sub)systems. He feels that, in the absence of such theory, most researcher are over-ready to accept the theoretical solutions found for interpretation of political phenomena in other countries. He sees a need for a stronger methodological bases for future research, either 1) in complementary usage of different sources and ways of collecting data, or 2) in including more of a historical dimension in different attempts to explain the political subsystem in Yugoslavia.

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The past decade has brought significant advancements in seasonal climate forecasting. However, water resources decision support and management continues to be based almost entirely on historical observations and does not take advantage of climate forecasts. This study builds on previous work that conditioned streamflow ensemble forecasts on observable climate indicators, such as the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) for use in a decision support model for the Highland Lakes multi-reservoir system in central Texas operated by the Lower Colorado River Authority (LCRA). In the current study, seasonal soil moisture is explored as a climate indicator and predictor of annual streamflow for the LCRA region. The main purpose of this study is to evaluate the correlation of fractional soil moisture with streamflow using the 1950-2000 Variable Infiltration Capacity (VIC) Retrospective Land Surface Data Set over the LCRA region. Correlations were determined by examining different annual and seasonal combinations of VIC modeled fractional soil moisture and observed streamflow. The applicability of the VIC Retrospective Land Surface Data Set as a data source for this study is tested along with establishing and analyzing patterns of climatology for the watershed study area using the selected data source (VIC model) and historical data. Correlation results showed potential for the use of soil moisture as a predictor of streamflow over the LCRA region. This was evident by the good correlations found between seasonal soil moisture and seasonal streamflow during coincident seasons as well as between seasonal and annual soil moisture with annual streamflow during coincident years. With the findings of good correlation between seasonal soil moisture from the VIC Retrospective Land Surface Data Set with observed annual streamflow presented in this study, future research would evaluate the application of NOAA Climate Prediction Center (CPC) forecasts of soil moisture in predicting annual streamflow for use in the decision support model for the LCRA.

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Die Steuerung logistischer und produktionstechnischer Systeme ist heute durchgängig hierarchisch organisiert. Auch dezentrale und wandelbare Systeme mit eingebetteten fraktalen oder adaptiven Elementen oder Regelkreisen lassen sich in ihrer Gesamtheit stets auf eine zeitgenaue zentrale Planung zurückführen. „Realtime Logistics“ bezeichnet im Gegensatz hierzu die echtzeitnahe Materialflusssteuerung auf Basis einer autonomen, selbstgesteuerten Abwicklung der im einzelnen logistischen Objekt implementierten Mission. Hierzu werden mobile Softwareagenten eingesetzt, die zunächst synchron zum Objekt, und in Zukunft eingebettet im logistischen Objekt, laufen werden.

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Today’s material flow systems for mass customization or dynamic productions are usually realized with manual transportation systems. However new concepts in the domain of material flow and device control like function-oriented modularization and intelligent multi-agent-systems offer the possibility to employ changeable and automated material flow systems in dynamic production structures. These systems need the ability to react on unplanned and unexpected events autonomously.

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Starting off from the usual language of modal logic for multi-agent systems dealing with the agents’ knowledge/belief and common knowledge/belief we define so-called epistemic Kripke structures for intu- itionistic (common) knowledge/belief. Then we introduce corresponding deductive systems and show that they are sound and complete with respect to these semantics.

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In many designs for radioactive waste repositories, cement and clay will come into direct contact. The geochemical contrast between cement and clay will lead to mass fluxes across the interface, which consequently results in alteration of structural and transport properties of both materials that may affect the performance of the multi-barrier system. We present an experimental approach to study cement-clay interactions with a cell to accommodate small samples of cement and clay. The cell design allows both in situ measurement of water content across the sample using neutron radiography and measurement of transport parameters using through-diffusion tracer experiments. The aim of the high- resolution neutron radiography experiments was to monitor changes in water content (porosity) and their spatial extent. Neutron radiographs of several evolving cement-clay interfaces delivered quantitative data which allow resolving local water contents within the sample domain. In the present work we explored the uncertainties of the derived water contents with regard to various input parameters and with regard to the applied image correction procedures. Temporal variation of measurement conditions created absolute uncertainty of the water content in the order of ±0.1 (m3/m3), which could not be fully accounted for by correction procedures. Smaller relative changes in water content between two images can be derived by specific calibrations to two sample regions with different, invariant water contents.