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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.
441

Modélisation et implémentation de simulations multi-agents sur architectures massivement parallèles / Modeling and implementing multi-agents based simulations on massively parallel architectures

Hermellin, Emmanuel 18 November 2016 (has links)
La simulation multi-agent représente une solution pertinente pour l’ingénierie et l’étude des systèmes complexes dans de nombreux domaines (vie artificielle, biologie, économie, etc.). Cependant, elle requiert parfois énormément de ressources de calcul, ce qui représente un verrou technologique majeur qui restreint les possibilités d'étude des modèles envisagés (passage à l’échelle, expressivité des modèles proposés, interaction temps réel, etc.).Parmi les technologies disponibles pour faire du calcul intensif (High Performance Computing, HPC), le GPGPU (General-Purpose computing on Graphics Processing Units) consiste à utiliser les architectures massivement parallèles des cartes graphiques (GPU) comme accélérateur de calcul. Cependant, alors que de nombreux domaines bénéficient des performances du GPGPU (météorologie, calculs d’aérodynamique, modélisation moléculaire, finance, etc.), celui-ci est peu utilisé dans le cadre de la simulation multi-agent. En fait, le GPGPU s'accompagne d’un contexte de développement très spécifique qui nécessite une transformation profonde et non triviale des modèles multi-agents. Ainsi, malgré l'existence de travaux pionniers qui démontrent l'intérêt du GPGPU, cette difficulté explique le faible engouement de la communauté multi-agent pour le GPGPU.Dans cette thèse, nous montrons que, parmi les travaux qui visent à faciliter l'usage du GPGPU dans un contexte agent, la plupart le font au travers d’une utilisation transparente de cette technologie. Cependant, cette approche nécessite d’abstraire un certain nombre de parties du modèle, ce qui limite fortement le champ d’application des solutions proposées. Pour pallier ce problème, et au contraire des solutions existantes, nous proposons d'utiliser une approche hybride (l'exécution de la simulation est partagée entre le processeur et la carte graphique) qui met l'accent sur l'accessibilité et la réutilisabilité grâce à une modélisation qui permet une utilisation directe et facilitée de la programmation GPU. Plus précisément, cette approche se base sur un principe de conception, appelé délégation GPU des perceptions agents, qui consiste à réifier une partie des calculs effectués dans le comportement des agents dans de nouvelles structures (e.g. dans l’environnement). Ceci afin de répartir la complexité du code et de modulariser son implémentation. L'étude de ce principe ainsi que les différentes expérimentations réalisées montre l'intérêt de cette approche tant du point de vue conceptuel que du point de vue des performances. C'est pourquoi nous proposons de généraliser cette approche sous la forme d'une méthodologie de modélisation et d'implémentation de simulations multi-agents spécifiquement adaptée à l'utilisation des architectures massivement parallèles. / Multi-Agent Based Simulations (MABS) represents a relevant solution for the engineering and the study of complex systems in numerous domains (artificial life, biology, economy, etc.). However, MABS sometimes require a lot of computational resources, which is a major constraint that restricts the possibilities of study for the considered models (scalability, real-time interaction, etc.).Among the available technologies for HPC (High Performance Computing), the GPGPU (General-Purpose computing on Graphics Processing Units) proposes to use the massively parallel architectures of graphics cards as computing accelerator. However, while many areas benefit from GPGPU performances (meteorology, molecular dynamics, finance, etc.). Multi-Agent Systems (MAS) and especially MABS hardly enjoy the benefits of this technology: GPGPU is very little used and only few works are interested in it. In fact, the GPGPU comes along with a very specific development context which requires a deep and not trivial transformation process for multi-agents models. So, despite the existence of works that demonstrate the interest of GPGPU, this difficulty explains the low popularity of GPGPU in the MAS community.In this thesis, we show that among the works which aim to ease the use of GPGPU in an agent context, most of them do it through a transparent use of this technology. However, this approach requires to abstract some parts of the models, what greatly limits the scope of the proposed solutions. To handle this issue, and in contrast to existing solutions, we propose to use a nhybrid approach (the execution of the simulation is shared between both the processor and graphics card) that focuses on accessibility and reusability through a modeling process that allows to use directly GPU programming while simplifying its use. More specifically, this approach is based on a design principle, called GPU delegation of agent perceptions, consists in making a clear separation between the agent behaviors, managed by the processor, and environmental dynamics, handled by the graphics card. So, one major idea underlying this principle is to identify agent computations which can be transformed in new structures (e.g. in the environment) in order to distribute the complexity of the code and modulate its implementation. The study of this principle and the different experiments conducted show the advantages of this approach from both a conceptual and performances point of view. Therefore, we propose to generalize this approach and define a comprehensive methodology relying on GPU delegation specifically adapted to the use of massively parallel architectures for MABS.
442

Distribution of Control Effort in Multi-Agent Systems : Autonomous systems of the world, unite!

Axelson-Fisk, Magnus January 2020 (has links)
As more industrial processes, transportation and appliances have been automated or equipped with some level of artificial intelligence, the number and scale of interconnected systems has grown in the recent past. This is a development which can be expected to continue and therefore the research in performance of interconnected systems and networks is growing. Due to increased automation and sheer scale of networks, dynamically scaling networks is an increasing field and research into scalable performance measures is advancing. Recently, the notion gamma-robustness, a scalable network performance measure, was introduced as a measurement of interconnected systems robustness with respect to external disturbances. This thesis aims to investigate how the distribution of control effort and cost, within interconnected system, affects network performance, measured with gamma-robustness. Further, we introduce a notion of fairness and a measurement of unfairness in order to quantify the distribution of network properties and performance. With these in place, we also present distributed algorithms with which the distribution of control effort can be controlled in order to achieve a desired network performance. We close with some examples to show the strengths and weaknesses of the presented algorithms. / I och med att fler och fler system och enheter blir utrustade med olika grader av intelligens så växer både förekomsten och omfattningen av sammankopplade system, även kallat Multi-Agent Systems. Sådana system kan vi se exempel på i traffikledningssystem, styrning av elektriska nätverk och fordonståg, vi kan också hitta fler och fler exempel på så kallade sensornätverk i och med att Internet of Things och Industry 4.0 används och utvecklas mer och mer. Det som särskiljer sammankopplade system från mer traditionella system med flera olika styrsignaler och utsignaler är att dem sammankopplade systemen inte styrs från en central styrenhet. Istället styrs dem sammankopplade systemen på ett distribuerat sätt i och med att varje agent styr sig själv och kan även ha individuella mål som den försöker uppfylla. Det här gör att analysen av sammankopplade system försvåras, men tidigare forskning har hittat olika regler och förhållninssätt för agenterna och deras sammankoppling för att uppfylla olika krav, såsom stabilitet och robusthet. Men även om dem sammankopplade systemen är både robusta och stabila så kan dem ha egenskaper som vi vill kunna kontrollera ytterligare. Specifikt kan ett sådant prestandamått vara systemens motståndskraft mot påverkan av yttre störningar och i vanliga olänkade system finns det en inneboende avvägning mellan kostnad på styrsignaler och resiliens mot yttre störningar. Samma avvägning hittar vi i sammankopplade system, men i dessa system hittar vi också ytterligare en dimension på detta problem. I och med att ett visst mått av en nätverksprestanda inte nödvändigtvis betyder att varje agent i nätverket delar samma mått kan agenterna i ett nätverk ha olika utväxling mellan styrsignalskostnad och resiliens mot yttre störningar. Detta gör att vissa agenter kan ha onödigt höga styrsignalskonstander, i den mening att systemen skulle uppnå samma nätverksprestanda men med lägre styrsignalskostnad om flera av agenterna skulle vikta om sina kontrollinsatser. I det här examensarbetet har vi studerat hur olika val av kontrollinsats påverkar ett sammankopplat systems prestanda. Vi har gjort detta för att undersöka hur autonoma, men sammankopplade, agenter kan ändra sin kontrollinsats, men med bibehållen nätverksprestanda, och på det sättet minska sina kontrollkostnader. Detta har bland annat resulterat i en distruberad algoritm för att manipulera agenternas kontrollinsats så att skillnaderna mellan agenternas resiliens mot yttre störningar minskar och nätverksprestandan ökar. Vi avslutar rapporten med att visa ett par exempel på hur system anpassade med hjälp av den framtagna algoritmen får ökad prestanda. Avslutningsvis följer en diskussion kring hur vissa antaganden kring systemstruktur kan släppas upp, samt kring vilka områden framtida forskning skulle kunna fortsätta med.
443

A Multi-Agent System with Negotiation Agents for E-Trading of Securities

Bahar Shanjani, Mina January 2014 (has links)
The financial markets have been started to get decentralized and even distributed. Consumers can now purchase stocks from their home computers without the use of a traditional broker. The dynamism and unpredictability of this domain which is continuously growing in complexity and also the giant volume of information which can affect this market, makes it one of the best potential domains to take advantage of agents. This thesis considers the main concerns of securities e-trading area in order to highlight advantages and disadvantages of multi-agent negotiating systems for online trading of securities comparing to single-agent systems. And then presents a multi-agent system design named MASTNA which considers both decision making and negotiating. The design seeks to improve the main concerns of securities e-trading such as speed, accuracy and handling complexities. MASTNA works over a distributed market and engages different types of agents in order to perform different tasks. For handling the negotiations MASTNA takes advantage of mobile negotiator agents with the purpose of handling parallel negotiations over an unreliable network (Internet).
444

INTELLIGENT SELF ADAPTING APPAREL TO ADAPT COMFORT UTILITY

Minji Lee (10725849) 30 April 2021 (has links)
<div>Enhancing the capability to control a tremendous range of physical actuators and sensors, combined with wireless technology and the Internet of Things (IoT), apparel technologies play a significant role in supporting safe, comfortable and healthy living, observing each customer’s conditions. Since apparel technologies have advanced to enable humans to work as a team with the clothing they wear, the interaction between a human and apparel is further enhanced with the introduction of sensors, wireless network, and artificially intelligent techniques. A variety of wearable technologies have been developed and spread to meet the needs of customers, however, some wearable devices are considered as non-practical tech-oriented, not consumer-oriented.</div><div>The purpose of this research is to develop an apparel system which integrates intelligent autonomous agents, human-based sensors, wireless network protocol, mobile application management system and a zipper robot. This research is an augmentation to the existing research and literature, which are limited to the zipping and unzipping process without much built in intelligence. This research is to face the challenges of the elderly and people with self-care difficulties. The intent is to provide a scientific path for intelligent zipper robot systems with potential, not only to help people, but also to be commercialized.</div><div>The research develops an intelligent system to control of zippers fixed on garments, based on the profile and desire of the human. The theoretical and practical elements of developing small, integrated, intelligent zipper robots that interact with an application by using a lightweight MQTT protocol for application in the daily lives of diverse populations of people with physical challenges. The system functions as intelligent automatized garment to ensure users could positively utilize a zipper robot device to assist in putting on garments which also makes them feel comfortable wearing and interacting with the system. This research is an approach towards the “future of fashion”, and the goal is to incentivize and inspire others to develop new instances of wearable robots and sensors that help people with specific needs to live a better life.</div>
445

Quantile Regression Deep Q-Networks for Multi-Agent System Control

Howe, Dustin 05 1900 (has links)
Training autonomous agents that are capable of performing their assigned job without fail is the ultimate goal of deep reinforcement learning. This thesis introduces a dueling Quantile Regression Deep Q-network, where the network learns the state value quantile function and advantage quantile function separately. With this network architecture the agent is able to learn to control simulated robots in the Gazebo simulator. Carefully crafted reward functions and state spaces must be designed for the agent to learn in complex non-stationary environments. When trained for only 100,000 timesteps, the agent is able reach asymptotic performance in environments with moving and stationary obstacles using only the data from the inertial measurement unit, LIDAR, and positional information. Through the use of transfer learning, the agents are also capable of formation control and flocking patterns. The performance of agents with frozen networks is improved through advice giving in Deep Q-networks by use of normalized Q-values and majority voting.
446

Cooperative Perception in Multi-agent Systems

Gautham Vinod (11033205) 23 July 2021 (has links)
<div>This thesis presents work and simulations containing the use of Artificial Intelligence for Unmanned Aerial Vehicles in search and rescue and/or surveillance operations. The goal is to create a vision system that leverages Artificial Intelligence, mainly Deep Learning techniques to build a pipeline that enables fast and accurate classification of the environment of the robot. Deep Neural Networks are trained and tested on ’emergency situational data. Further, the power of this vision system is leveraged to extend the problem onto a multiagent system to handle fault tolerance. The multi-agent system is also made resilient to Byzantine malicious attacks to help improve the reliability of the system.</div><div><br></div><div>This thesis also shows the use of Artificial Intelligence for effective surveillance for defense related purposes. Tracking the GPS coordinates of a boat using only the video of the boat captured by a camera and the GPS coordinates of the camera itself is demonstrated. The solution was tested by the Department of Defense - Department of the Navy, Naval Information Warfare Center Pacific.</div>
447

Zpětnovazební učení pro kooperaci více agentů / Cooperative Multi-Agent Reinforcement Learning

Uhlík, Jan January 2021 (has links)
Deep Reinforcement Learning has achieved a plenty of breakthroughs in the past decade. Motivated by these successes, many publications extend the most prosperous algorithms to multi-agent systems. In this work, we firstly build solid theoretical foundations of Multi-Agent Reinforcement Learning (MARL), along with unified notations. Thereafter, we give a brief review of the most influential algorithms for Single-Agent and Multi-Agent RL. Our attention is focused mainly on Actor-Critic architectures with centralized training and decentralized execution. We propose a new model architec- ture called MATD3-FORK, which is a combination of MATD3 and TD3-FORK. Finally, we provide thorough comparative experiments of these algorithms on various tasks with unified implementation.
448

Adaptivní algoritmy matchmakingu pro výpočetní multi-agentní systémy / Adaptive Matchmaking Algorithms for Computational Multi-Agent Systems

Kazík, Ondřej January 2014 (has links)
The multi-agent systems (MAS) has proven their suitability for implementation of complex software systems. In this work, we have analyzed and designed the data mining MAS by means of role-based organizational model. The organiza- tional model and the model of data mining methods have been formalized in the description logic. By matchmaking which is the main subject of our research, we understand the recommendation of computational agents, i.e. agents encap- sulating some computational method, according their capabilities and previous performances. The matchmaking thus consist of two parts: querying the ontol- ogy model and the meta-learning. Three meta-learning scenarios were tested: optimization in the parameter space, multi-objective optimization of data min- ing processes and method recommendation. A set of experiments in these areas have been performed. 1
449

PaySim Financial Simulator : PaySim Financial Simulator

Elmir, Ahmad January 2016 (has links)
The lack of legitimate datasets on mobile money transactions toperform research on in the domain of fraud detection is a big prob-lem today in the scientic community. Part of the problem is theintrinsic private nature of mobile transactions, not much infor-mation can be exploited. This will leave the researchers with theburden of rst harnessing the dataset before performing the actualresearch on it. The dataset corresponds to the set of data in whichthe research is to be performed on. This thesis discusses a solutionto such a problem, namely the Paysim simulator. Paysim is a -nancial simulator that simulates mobile money transactions basedon an original dataset. We present a solution to ultimately yieldthe possibility to simulate mobile money transactions in such a waythat they become similar to the original dataset. The similarity orthe congruity will be measured by calculating the error-rate betweenthe synthetic data set and the original data set. With technologyframeworks such as "Agent Based" simulation techniques, and theapplication of mathematical statistics, it can be demonstrated thatthe synthetic data is as prudent as the original data set. The aimof this thesis is to demonstrate with statistical models that PaySimcan be used as a tool for the intents of nancial simulations.
450

Dynamic Structure Adaptation for Communities of Learning Machines

LeJeune, Kennan Clark 23 May 2022 (has links)
No description available.

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