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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

[en] FIOT: AN AGENT-BASED FRAMEWORK FOR SELF-ADAPTIVE AND SELF-ORGANIZING INTERNET OF THINGS APPLICATIONS / [pt] FIOT: UM FRAMEWORK BASEADO EM AGENTES PARA APLICAÇÕES AUTO-ORGANIZÁVEIS E AUTOADAPTATIVAS DE INTERNET DAS COISAS

NATHALIA MORAES DO NASCIMENTO 01 June 2016 (has links)
[pt] A ideia principal da Internet das Coisas (IoT) é conectar bilhões de coisas à Internet nos próximos anos, a exemplo de carros, roupas e comidas. Entretanto, muitos problemas precisam ser resolvidos antes que essa ideia possa ser concretizada. Alguns desses problemas estão relacionados à necessidade de construir sistemas para IoT que sejam auto-organizáveis e autoadaptativos. Este trabalho, portanto, apresenta a elaboração do Framework para Internet das Coisas (FIoT), que oferece suporte ao desenvolvimento de aplicações para IoT com essas características. Ele é baseado nos paradigmas de Sistemas Multiagente (SMA) e algumas técnicas abordadas em Aprendizado de Máquina, a exemplo de redes neurais e algoritmos evolutivos. Um agente pode ter algumas características, como autonomia e sociabilidade, que tornam SMAs compatíveis com sistemas que requerem auto-organização. Redes neurais e algoritmos de evolução vêm sendo comumente usados nos estudos de robótica, no intuito de prover autonomia e adaptação à agentes físicos (ex.: robôs, sensores). Para demonstrar o uso do FIoT, dois grupos de problemas em IoT serão instanciados: (i) Cidades Inteligentes e (ii) Quantificação de Coisas. / [en] The agreed fact about the Internet of Things (IoT) is that, within the coming years, billions of resources, such as cars, clothes and foods will be connected to the Internet. However, several challenging issues need to be addressed before the IoT vision becomes a reality. Some open problems are related to the need of building self-organizing and self-adaptive IoT systems. To create IoT applications with these features, this work presents a Framework for Internet of Things (FIoT). Our approach is based on concepts from Multi-Agent Systems (MAS) and Machine Learning Techniques, such as a neural network and evolutionary algorithms. An agent could have characteristics, such as autonomy and social ability, which makes MAS suitable for systems requiring self-organization (SO). Neural networks and algorithms of evolution have been commonly used in robotic studies to provide embodied agents (as robots and sensors) with autonomy and adaptive capabilities. To illustrate the use of FIoT, we derived two different instances from IoT applications: (i) Quantified Things and (ii) Smart Cities. We show how exible points of our framework are instantiated to generate an application.
192

A COMPUTATIONAL MODEL OF TEAM-LEVEL NEGOTIATION: WITH AN APPLICATION IN CREATIVE PROBLEM SOLVING

Zahra Sajedinia (11177388) 26 July 2021 (has links)
The ability to solve problems creatively has been crucial for the adaptation and survival of humans throughout history. In many real–life situations, cognitive processes are not isolated. Humans are social, they communicate and form groups to solve daily problems and make decisions. Therefore, the final output of cognitive processes can come from multi–brains in groups rather than an individual one. This multi–brain output can be largely different from the output that an individual person produces in isolation. As a result, it is essential to include team–level processes in cognitive models to make a more accurate description of real– world cognitive processes in general and problem solving in particular. This research aims to answer the general question of how working in a team affects creative problem solving. For doing that, first, we propose a computational model for multi-agent creative problem solving. Then, we show how the model can be used to study the factors that are involved in creativity in teams and potentially will suggest answers to questions such as, ‘how team size is related to creativity’.
193

A User-Friendly Approach for Applying Multi-Agent Technology in Plug & Produce Systems / En användarvänlig strategi för att tillämpa multiagentteknologi för Plug & Produce

Bennulf, Mattias January 2020 (has links)
This thesis presents methods for simplifying the use of multi-agent systems in Plug & Produce. The demand for customized products and low volume production is constantly increasing. The industry has for many years used dedicated manufacturing systems where it is difficult and expensive to adapt to new product designs. Instead, factories are forced to use human workers for certain tasks that demand high flexibility and rapid adaption for new product designs. Several solutions have been proposed over the years to create highly flexible automation systems that automatically handles rapid adaption for new products. A concept called Plug & Produce aims at creating a system where resources and parts can be added in minutes rather than days in dedicated systems. One promising solution for implementing Plug & Produce is the distributed approach called multi-agent systems, where each resource and part get its own controller that communicates with each other to reach manufacturing goals. The idea is that the system automatically handles the adaption for new products. However, still today the use of such systems is extremely limited in the industry. One reason is the lack of mature multi-agent systems that are easy to use and that hides the complexity of the underlying agent system from the users. This is a huge problem since these systems tend to be more complex than traditional approaches. Thus, this thesis focuses on simplifying the use of multi-agent systems by proposing various methods for bringing the multi-agent technology for Plug & Produce closer to the industry. / Denna avhandling presenterar metoder för att förenkla användningen av multiagent-system för Plug & Produce. Efterfrågan på kundanpassade produkter och lågvolymproduktion ökar ständigt. Industrin har under många år använt sig avdedikerade tillverkningssystem som gör det både svårt och dyrt att anpassa sig till nya produktdesigner. Istället tvingas fabriker att antälla onödigt många operatörer för vissa arbetsuppgifter där det krävs hög flexibilitet och snabb anpassning till nya produktdesigner. Flera lösningar har föreslagits under åren för att skapa flexibla automatiseringssystem som automatiskt hanterar snabb omställning till nya produkter. Ett koncept som heter Plug & Produce handlar om att skapa system där nya typer av resurser och produkter kan kopplas in i systemet på ett fåtal minuter snarare än dagar i traditionella system. För att implementera Plug & Produce kan multi-agent-system användas, där varje resurs och produkt får sin egen styrning. Agenterna kan sedan kommunicera med varandra för att nå de mål som satts upp för tillverkningen av produkterna. Tanken är att systemet automatiskt hanterar anpassningen till nya produkter. Idag är dock användningen av sådana system extremt begränsad i industrin. En av anledningarna är avsaknaden av mogna multi-agent-system som är lätta att använda och där komplexiteten hos det underliggande agensystemet kan döljas från användaren. Detta är ett stort problem eftersom multi-agent-system tenderar att vara mer komplexa än traditionella system. Därför fokuserar denna avhandling på att förenkla användningen av multi-agent-system genom att föreslå olika metoder som kan underlätta användandet av multi-agent-tekniken för Plug & Produce i industrin.
194

Approche multi-agents pour les problèmes de partage / A multiagent approach for resource sharing problems

Damamme, Jonathan 12 December 2016 (has links)
Cette thèse porte sur le problème d'allocation de ressource décentralisée, sans argent, où les agents n'ont qu'une connaissance partielle sur le système. L'approche de la thèse sera d'utiliser des échanges locaux, plus exactement des swaps, c'est-à-dire des échanges bilatéraux où chaque agent donne une ressource en échange d'un autre. Le travail se divise en deux parties. La première se concentre sur les problèmes de house market, avec une approche très simple et les agents travaillent sans les connaissances. Le but sera de montrer qu'elle a quand même une performance honorable. Je mettrais en valeur notamment que l'algorithme s'en sort bien par rapport à ceux de la littérature. Et je montrerais même que dans le domaine unimodal, l'algorithme est Pareto-optimal. La deuxième se présente dans une situation plus générale, et où le mécanisme présenté est divisée en 3 parties : protocole de contact, protocole de négociation, et conditions d'arrêt. chaque partie a plusieurs variantes. Je les décrirais et je les testerais expérimentalement. / This thesis covers distributed resources allocation setting, without money balance, where agents have limited knowledge of the system. This thesis will use local swaps, i.e. bilateral deals, where one resource is exchanged for another. This work is divided in two parts. The first part focus the house market, with a very simple mechanism and agents don't use knowledge. The aim will to show that it has however good performances. For this, I will compare the algorithm with those of literature. I will also prove that in the single-peaked domains, this mechanism is Pareto-optimal. The second part examines a general framework. The mechanism contains three sub-protocols : contact protocol, negotiation protocols, and stop conditions. Each protocol will be described and experimented.
195

Intergiciel agent pour le déploiement et la configuration d'applications distribuées dans des environnements ambiants / An agent middleware for the deployment and the configuration of distributed applications in ambient environments

Piette, Ferdinand 17 January 2017 (has links)
L'évolution des technologies de l'information ainsi que la miniaturisation constante des composants électroniques de ces dernières décennies ont permis de doter les objets de la vie de tous les jours de capacités de calcul et de communication. Ces objets connectés sont disséminés dans l'environnement de l'utilisateur et coopèrent les uns avec les autres afin de fournir à l'utilisateur des services intelligents de manière totalement transparente et non intrusive. Ces environnements sont caractérisés par une grande hétérogénéité ainsi qu'une grande dynamicité. Les intégrations dites verticales (les données des capteurs sont externalisées sur les serveurs d'une entreprise) permettent certes une interopérabilité plus importante, mais engendrent des problèmes de saturation des canaux de communication, ainsi que des questionnements sur la sécurité et la confidentialité de des informations. Pour pallier ces problèmes, les intégrations dites horizontales (les entités matérielles sont mises en relation directement au sein de l'infrastructure) sont encouragées. Dans cette thèse, nous adressons le problème du déploiement et de la configuration automatique d'applications au sein de tels environnements ambiants. Nous proposons des mécanismes permettant, à partir d'une description de l'environnement ambiant, la sélection et la configuration d'entités matérielles qui supporteront l'exécution des applications. Ces mécanismes ont été encapsulé dans un intergiciel basé sur le paradigme Multi-agents dans lequel les différents agents logiciels du système collaborent afin de sélectionner les entités de l'infrastructure respectant les besoins et les contraintes des applications à déployer. / Research domains like Ambient Intelligence or Internet of Things came up in the early 2000’s with the technologic improvement and the ongoing miniaturization of electronic devices. These electronic and information devices are scattered in the user’s environment, can communicate and exchange data more and more easily to provide intelligent and non-intrusive services to the users. However, it is difficult to have generic implementations of these applications. These difficulties are due the the high heterogeneity and dynamicity of the ambient environments. Vertical integrations of connected devices (data exchanges from the devices to external servers) allow more interoperability but generate overloads of the communication channels and privacy concerns. To prevent these problems, horizontal approaches (connected devices communicate directly together through the hardware infrastructure) have to be encouraged. In this thesis work, we address the problem of the automatic deployment and configuration of distributed applications in these ambient environments. We propose mechanisms that allow, from a description of the environment, the selection and the configuraion of the hardware entities that will support the execution of applications. These mechanisms are encapsulated in a middleware based on the multi-agent paradigm. The different agents of the system cooperate in order to select the right hardware entities that respects the requirements and the constraints of the applications we want to deploy.
196

Détection des communautés dans les réseaux sociaux dynamiques : une approche multi-agents / Community detection in dynamic social network : Multi-agent approach

Zardi, Hédia 09 March 2016 (has links)
L’analyse des réseaux sociaux a conduit à la découverte d’une propriété très intéressante : ces réseaux se caractérisent par l’existence de zones de forte densité constituées d’éléments fortement connectés entre eux. Ces zones appelées "communautés", évoluent au cours du temps suivant la dynamique des acteurs sociaux et de leurs interactions. L’identification de ces communautés offre un éclairage intéressant sur la structure du réseau et permet de suivre leur évolution au fil du temps. Bien que ce problème ait donné lieu à de très nombreux travaux ces dernières années, la détection des communautés dynamiques reste encore un problème ouvert et aucune solution entièrement satisfaisante n’est encore proposée. Dans ce travail, nous proposons une approche multi-agents pour la détection des communautés dans les réseaux sociaux dynamiques. Les entités de notre approche observent l’évolution du réseau, et en conséquence, elles adaptent en temps réel le graphe représentant le réseau et elles engendrent les modifications adéquates sur les communautés précédemment détectées. Cette approche permet de modéliser le réseau par un graphe dynamique qui s’adapte en fonction l’évolution observée dans le réseau. Pour cette modélisation, plusieurs aspects du réseau sont intégrés : la structure topologique du graphe, la similarité sémantiques des membres sociaux et la communication entre eux. Cette modélisation se base sur le concept d’homophilie et sur une stigmergie à base des phéromones. Afin d’étudier les performances de l’approche proposée, nous l’avons appliquée sur un ensemble très varié de graphes réels et artificiels. Les résultats ont été suffisamment satisfaisants et montrent la bonne performance de notre modèle. / Analysis of social networks has led to the discovery of a very interesting property : these networks are characterized by the existence of areas with high density composed of highly interconnected elements. These areas called "communities", evolve over time according to the dynamic of social members and their interactions. The identification of these communities offers an interesting light on the network structure and it allows to track their progress over time. Although this problem has been the subject of numerous studies in recent years, the detection of dynamic communities remains an open problem and no fully satisfactory solution has yet been proposed. In this work, we propose a multi-agent approach for the detection of communities in dynamic social networks. The entities of our approach observe the evolution of the network and consequently they adapt in real time the graph representing the network and they generate the appropriate changes on previously identified communities. This approach allows to model the network by a graph that dynamically adapts according to the evolution of the network. For this modeling, several network’s aspects are integrated: the topological structure of the graph, the semantic similarity of social members and the communication between them. This modeling is based on the concept of homophily and a pheromone based stigmergy. In order to study the performances of the proposed approach, we applied it to a divers set of real and artificial graphs. The results were satisfactory enough and show the good performance of our model.
197

New Approaches Towards Online, Distributed, and Robust Learning of Statistical Properties of Data

Tong Yao (16644750) 07 August 2023 (has links)
<p>In this thesis, we present algorithms to allow agents to estimate certain properties in a robust, online, and distributed manner. Each agent receives a sequence of observations, and through communication, collectively infers properties of the data gathered by all agents by communicating.</p> <p><br></p> <p>In the first part of the thesis, we provide algorithms to infer the correlations between interacting entities from these large datasets. Gaussian graphical models have been well studied to represent the relationships between the various random variables which generate data, and numerous algorithms have been proposed to learn the dependencies in such models. However, existing algorithms typically process data in a batch at a central location, limiting their applications in scenarios where data arrive in real-time and are gathered by different agents.  </p> <p><br></p> <p>To address these challenges, first, we propose an online sparse inverse covariance algorithm to infer the static network structure (i.e., dependencies between nodes) in real-time from time-series data, in a centralized location. Subsequently, we propose a distributed algorithm to cooperatively learn the network structure in real-time from data collected by distributed agents. We characterize the theoretical convergence properties and provide simulations using synthetic datasets and real-world hurricane Twitter datasets in disaster management applications.    </p> <p><br></p> <p>The second part of this thesis addresses the robustness of online and distributed learning under arbitrary data corruption. We propose online and distributed algorithms for robust mean, covariance, and sparse inverse covariance estimation. These algorithms are capable of operating effectively even in the presence of adversarial data attacks. We provide theoretical bounds on the error and rate of convergence of these methods and evaluate their performance under various settings.</p> <p><br></p> <p>Finally, we consider the problem of classification with a network of heterogeneous and partially informative agents, each receiving local data from an underlying true class, and equipped with a classifier that only distinguishes between a subset of the entire set of classes. We propose an iterative algorithm that uses the posterior probabilities of any classifier and recursively updates each agent's local belief based on its local signals and belief information from its neighbors. We then adopt a novel distributed min-rule to update each agent’s global belief and enable learning of the true class for all agents. We analyze the convergence properties of our proposed algorithm, and subsequently, demonstrate and compare its performance with local averaging and global average consensus through simulations and with a visual image dataset.</p>
198

Modelling Financial Markets via Multi-Agent Reinforcement Learning : How nothing interesting happened when I made AI trade with AI / Modellering av finansmarknader med hjälp av Multi-Agent Förstärkningsinlärning : Hur inget intressant hände när jag fick AI att handla med AI

Bocheński, Mikołaj January 2022 (has links)
The numerous previous attempts to simulate financial markets tended to be based on strong assumptions about markets or their participants. This thesis describes a more general kind of model - one in which deep reinforcement learning is used to train agents to make a profit while trading with each other on a virtual exchange. Such a model carries less inductive bias than most others - in theory, a neural network is capable of learning arbitrary decision rules. The model itself led to very simple results, but the conclusions from its construction will hopefully be of guidance to anyone implementing such a model in the future. / De många tidigare försöken att simulera finansmarknader har ofta byggt på starka antaganden om marknaderna eller deras deltagare. I den här avhandlingen beskrivs en mer allmän typ av modell - en modell där djup förstärkningsinlärning används för att träna agenter att göra vinst när de handlar med varandra på en virtuell börs. En sådan modell har mindre induktiva fördomar än de flesta andra - i teorin kan ett neuralt nätverk lära sig godtyckliga beslutsregler. Själva modellen ledde till mycket enkla resultat, men slutsatserna från dess konstruktion kommer förhoppningsvis att vara vägledande för alla som tillämpar en sådan modell i framtiden.
199

Optimal Path Planning for Aerial Swarm in Area Exploration / Optimal ruttplanering för en drönarsvärm

Norén, Johanna January 2022 (has links)
This thesis presents an approach to solve an optimal path planning problem for a swarm of drones. We optimize and improve information retrieval in area exploration within applications such a ‘Search and Rescue’-missions or reconnaissance missions. For this, dynamic programming has been used as a solving approach for a optimization problem. Different scenarios have been examined for two types of system, a single-agent system and a multi-agent system. First, there have been restrictions on the agents movement in a grid map and for that, optimal paths have been computed for both systems. Thereafter, two different solving approaches within dynamic programming have been tested and compared. The greedy approach which is a standard use where each agent computes the most optimal path from its own perspective and a simultaneous solving approach where the agents compute the most optimal paths according to all agents perspective. The simultaneous solving approach performed better than the greedy approach, which was expected since it is a more swarm optimal approach. However, it has a higher computational complexity which grows exponentially unlike to the greedy approach. Lastly, we discuss the case when the agents are allowed to move in all directions to optimize the information retrieval for the swarm. Here, dynamic programming turns out to have limitations for our use and purpose. For future work, a suggestion is to model the problem with multiple objective functions instead of one as has been done in this thesis. Also, it would be interesting trying another solving method for the problem. To this, I give example of two methods that would be interesting to compare, using model predictive control or a machine learning-based solution such as reinforcement learning. / Denna avhandling presenterar ett tillvägagångssätt för att lösa ett optimalt ruttplanerings problem för en drönarsvärm. Vi optimerar och förbättrar informationsinhämtningen i områdesutforskning inom applikationer som ’Search and Rescue’-uppdrag eller spaningsuppdrag. För detta har dynamisk programmering använts som en lösningsmetod till optimeringsproblem. Olika scenarier har undersökts för två typer av system, ett en-agent system och ett fler-agent system. Först har agenterna varit begränsade hur de har fått röra sig i en rutnätskarta och för det fallet har optimala vägar beräknats för båda systemen. Därefter har två olika lösningssätt inom dynamisk programmering testats och jämförts. Det giriga tillvägagångssättet som är en standardanvändning där varje agent beräknar den mest optimala vägen ur sitt eget perspektiv och en simultan lösningsmetod där agenterna beräknar de mest optimala vägarna enligt alla agenters perspektiv. Den simultana lösningsstrategin presterade bättre än den giriga, vilket var väntat eftersom det är ett mer svärmoptimalt tillvägagångssätt. Den har dock en högre beräkningskomplexitet som växer exponentiellt jämfört med den giriga metoden. Till sist diskuterar vi fallet då agenterna får röra sig i alla riktningar för att optimera informationssökningen för svärmen. Här visar sig dynamisk programmering ha begränsningar för våran användning och syfte. För framtida arbete är ett förslag att modellera problemet med flera mål funktioner istället för en som har gjorts i denna avhandling. Det skulle också vara intressant att prova ett annat lösningssätt för problemet. Till detta ger jag exempel på två metoder som skulle vara intressanta att jämföra, genom att använda modell prediktiv styrning eller en maskininlärningsbaserad lösning såsom förstärkande inlärning.
200

VM Allocation in Cloud Datacenters Based on the Multi-Agent System. An Investigation into the Design and Response Time Analysis of a Multi-Agent-based Virtual Machine (VM) Allocation/Placement Policy in Cloud Datacenters

Al-ou'n, Ashraf M.S. January 2017 (has links)
Recent years have witnessed a surge in demand for infrastructure and services to cover high demands on processing big chunks of data and applications resulting in a mega Cloud Datacenter. A datacenter is of high complexity with increasing difficulties to identify, allocate efficiently and fast an appropriate host for the requested virtual machine (VM). Establishing a good awareness of all datacenter’s resources enables the allocation “placement” policies to make the best decision in reducing the time that is needed to allocate and create the VM(s) at the appropriate host(s). However, current algorithms and policies of placement “allocation” do not focus efficiently on awareness of the resources of the datacenter, and moreover, they are based on conventional static techniques. Which are adversely impacting on the allocation progress of the policies. This thesis proposes a new Agent-based allocation/placement policy that employs some of the Multi-Agent system features to get a good awareness of Cloud Datacenter resources and also provide an efficient allocation decision for the requested VMs. Specifically, (a) The Multi-Agent concept is used as a part of the placement policy (b) A Contract Net Protocol is devised to establish good awareness and (c) A verification process is developed to fully dimensional VM specifications during allocation. These new results show a reduction in response time of VM allocation and the usage improvement of occupied resources. The proposed Agent-based policy was implemented using the CloudSim toolkit and consequently was compared, based on a series of typical numerical experiments, with the toolkit’s default policy. The comparative study was carried out in terms of the time duration of VM allocation and other aspects such as the number of available VM types and the amount of occupied resources. Moreover, a two-stage comparative study was introduced through this thesis. Firstly, the proposed policy is compared with four state of the art algorithms, namely the Random algorithm and three one-dimensional Bin-Packing algorithms. Secondly, the three Bin-Packing algorithms were enhanced to have a two-dimensional verification structure and were compared against the proposed new algorithm of the Agent-based policy. Following a rigorous comparative study, it was shown that, through the typical numerical experiments of all stages, the proposed new Agent-based policy had superior performance in terms of the allocation times. Finally, avenues arising from this thesis are included. / Al al-Bayt University in Jordan.

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