Tesi sul tema "Distributed or decentralized control"
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1
Zhang, Zedong. "Decentralized control of distributed generation in future distribution networks". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/decentralized-control-of-distributed-generation-in-future-distribution-networks(aaffa96a-284f-4b04-a528-ee2bd98dba59).html.
Abstract (sommario):
Environmental targets set by governments around the world are leading to high penetrations of small to medium-scale renewable distributed generation (DG). High penetration of DG in distribution networks, however, can result in voltage and thermal issues among other technical problems. The traditional 'Fit & Forget' approach that refers to the passive use of assets with limited or no control, in the context of distribution network planning, is used to meet maximum demand or generation requirements. However, to ensure that more renewable generation is cost-effectively connected to distribution networks, it is imperative to adopt a more active control of network elements and participants. The active control of future distribution networks requires understanding the corresponding dependencies between voltage magnitudes and DG active/reactive power outputs to mitigate voltage issues. One classical method to calculate these dependencies is to use sensitivity approaches such as those based on the Jacobian matrix. However, during operation, updating the Jacobian matrix requires the network to be fully observable making it unfeasible for decentralized control approaches. Therefore, it is critical to develop a sensitivity approach only requiring local real-time information. This thesis proposes a novel approach to produce voltage sensitivity coefficients using the surface fitting technique based solely on knowledge of network characteristics and, therefore, no remote monitoring is required. To assess the performance of the proposed voltage sensitivity approach, a decentralized (local) voltage control algorithm that simultaneously caters for both the active and reactive power outputs of a single DG plant is adopted. Comparisons with classical sensitivity approaches are carried out using the 16-bus UK GDS test network, 1-min resolution demand and wind generation data. Persistence forecasting (i.e., assuming no changes in demand and wind in a short time period) is considered in this case. The lower Mean Squared Error (MSE) shows that the coefficients of the proposed sensitivity approach are close to those of the Jacobian matrix and better than the perturb-and-observe approach. In the context of voltage management, results highlight that the proposed sensitivity approach is more effective than the Jacobian matrix inverse and perturb-and-observe, resulting in better voltage compliance and energy harvesting (better capacity factor). It should be highlighted that this performance is achieved without the need of full network observability. Furthermore, to cater for the more realistic and complex case of multiple DG plants, this thesis proposes a time-delay based decentralized control algorithm. A comparison with an ideal AC Optimal Power Flow (OPF) is carried out using the same 16-bus UK GDS network but with seven DG plants. The results demonstrate that the proposed sensitivity approach and time delays are very effective when compared to the AC OPF. This, in turn, proves that the combined use of the proposed voltage sensitivity approach and the decentralized controller is an implementable, cost-effective solution to manage DG plants in distribution networks without the need of further communication infrastructure. Finally, a decentralized DG control logic with the capability of using wind forecasting techniques is proposed to tackle the unpredictable nature of wind power. In this work, a time-series based forecasting technique is incorporated to the proposed decentralized controller. The results confirm that the use of more advanced forecasting technique can further improve the management of renewable DG plants.
2
Schwartz, Jana Lyn. "The Distributed Spacecraft Attitude Control System Simulator: From Design Concept to Decentralized Control". Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28269.
Abstract (sommario):
A spacecraft formation possesses several benefits over a single-satellite mission. However, launching a fleet of satellites is a high-cost, high-risk venture. One way to mitigate much of this risk is to demonstrate hardware and algorithm performance in groundbased testbeds. It is typically difficult to experimentally replicate satellite dynamics in an Earth-bound laboratory because of the influences of gravity and friction. An air bearing provides a very low-torque environment for experimentation, thereby recapturing the freedom of the space environment as effectively as possible. Depending upon con- figuration, air-bearing systems provide some combination of translational and rotational freedom; the three degrees of rotational freedom provided by a spherical air bearing are ideal for investigation of spacecraft attitude dynamics and control problems.
An interest in experimental demonstration of formation flying led directly to the development of the Distributed Spacecraft Attitude Control System Simulator (DSACSS). The DSACSS is a unique facility, as it uses two air-bearing platforms working in concert. Thus DSACSS provides a pair of "spacecraft" three degrees of attitude freedom each. Through use of the DSACSS we are able to replicate the relative attitude dynamics between nodes of a formation such as might be required for co-observation of a terrestrial target.
Many dissertations present a new mathematical technique or prove a new theory. This dissertation presents the design and development of a new experimental system. Although the DSACSS is not yet fully operational, a great deal of work has gone into its development thus far. This work has ranged from configuration design to nonlinear analysis to structural and electrical manufacturing. In this dissertation we focus on the development of the attitude determination subsystem. This work includes development of the equations of motion and analysis of the sensor suite dynamics. We develop nonlinear filtering techniques for data fusion and attitude estimation, and extend this problem to include estimation of the mass properties of the system. We include recommendations for system modifications and improvements.Ph. D.
3
Vásquez, Quintero Juan Carlos. "Decentralized control techniques applied to electric power distributed generation in microgrids". Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/5956.
Abstract (sommario):
Distributed generation of electric energy has become part of the current electric power system. In this context a new scenario is arising in which small energy sources make up a new supply system: The microgrid.The most recent research projects show the technical difficulty of controlling the operation of microgrids, because they are complex systems in which several subsystems interact: energy sources, power electronic converters, energy storage systems, local, linear and non-linear loads and of course, the main grid. In next years, the electric grid will evolve from the current very centralized model toward a more distributed one. At the present time the generation, consumption and storage points are very far away one from each other. Under these circumstances, relatively frequent failures of the electric supply and important losses take place in the transport and distribution of energy, so that it can be stated that the efficiency of the supply system is low.
In another context, electric companies are aiming at an electric grid, formed in a certain proportion by distributed generators, where the consumption points are near the generation points, avoiding high losses in the transmission lines and reducing the rate of shortcomings. Summing up, it is pursued the generation of small quantities of electric power by the users (this concept is called microgeneration in the origin), considering them not only as electric power consumers but also as responsible for the generation, becoming this way an integral part of the grid.
In this context it is necessary to develop a new concept of flexible grid, i.e., with reconfiguration capability for operation with or without connection to the mains. The future microgrids should incorporate supervision and control systems that allow the efficient management of various kinds of energy generators, such as photovoltaic panels, energy storage systems, and local loads. Hence, we are dealing with intelligent flexible Microgrids capable of import and export power from/to the grid reconfiguring its operation modes and making decisions in real time.
The researching lineas that have been introduced in this thesis are focused on the innovation in this kind of systems, the integration of several renewable energy sources, the quality of the power supply, security issues, and the system behavior during faults.
In order to carry out some solutions related within these characteristics, the main goal of this thesis is the application on new control stretegies and a power management analysis of a microgrid. Thus, thanks to the emerging of renewable energy, is possible to give an alternative to the decoupling of generation units connected to the utility grid.
Likewise, a work methodology has been analyzed and developed based on the modeling, control parameters design, and power management control starting from a single voltage source inverter to a number of interconnected DG units forming flexible Microgrids. In addition, all the mencioned topics have been studied giving new system performances, viability and safe functioning, thanks to the small-signal analysis and introducing control loop design algorithms, improving the import/export of electric power and operating both grid connected mode and an island.
This thesis has presented an analysis, simulation and experimental results focusing on modeling, control, and analysis of DG units, giving contributions according to the following steps:
- Control-oriented modeling based on active and reactive power analysis
- Control synthesis based on enhanced droop control technique.
- Small-signal stability study to give guidelines for properly adjusting the control system parameters according to the desired dynamic response
This methodology has been extended to microgrids by using hierarchical control applied to droop-controlled line interactive UPSs showing that:
- Droop-controlled inverters can be used in islanded microgrids.
- By using multilevel control systems the microgrid can operate in both grid-connected and islanded mode, in a concept called flexible microgrid.
The proposed hierarchical control required for flexible Microgrids consisted of different control levels, as following:
- Primary control is based on the droop method allowing the connection of different AC sources without any intercommunication.
- Secondary control avoids the voltage and frequency deviation produced by the primary control. Only low bandwidth communications are needed to perform this control level. A synchronization loop can be added in this level to transfer from islanding to grid connected modes.
- Tertiary control allows the import/export of active and reactive power to the grid.
4
Cao, Yongcan. "Decentralized Coordination of Multiple Autonomous Vehicles". DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/652.
Abstract (sommario):
This dissertation focuses on the study of decentralized coordination algorithms of multiple autonomous vehicles. Here, the term decentralized coordination is used to refer to the behavior that a group of vehicles reaches the desired group behavior via local interaction. Research is conducted towards designing and analyzing distributed coordination algorithms to achieve desired group behavior in the presence of none, one, and multiple group reference states. Decentralized coordination in the absence of any group reference state is a very active research topic in the systems and controls society. We first focus on studying decentralized coordination problems for both single-integrator kinematics and double-integrator dynamics in a sampled-data setting because real systems are more appropriate to be modeled in a sampled-data setting rather than a continuous setting. Two sampled-data consensus algorithms are proposed and the conditions to guarantee consensus are presented for both fixed and switching network topologies. Because a number of coordination algorithms can be employed to guarantee coordination, it is important to study the optimal coordination problems. We further study the optimal consensus problems in both continuous-time and discrete-time settings via an linear-quadratic regulator (LQR)-based approach. Noting that fractional-order dynamics can better represent the dynamics of certain systems, especially when the systems evolve under complicated environment, the existing integer-order coordination algorithms are extended to the fractional-order case. Decentralized coordination in the presence of one group reference state is also called coordinated tracking, including both consensus tracking and swarm tracking. Consensus tracking refers to the behavior that the followers track the group reference state. Swarm tracking refers to the behavior that the followers move cohesively with the external leader while avoiding inter-vehicle collisions. In this part, consensus tracking is studied in both discrete-time setting and continuous-time settings while swarm tracking is studied in a continuous-time setting. Decentralized coordination in the presence of multiple group reference states is also called containment control, where the followers will converge to the convex hull, i.e., the minimal geometric space, formed by the group references states via local interaction. In this part, the containment control problem is studied for both single-integrator kinematics and double-integrator dynamics. In addition, experimental results are provided to validate some theoretical results.
5
Melhuish, C. R. "Strategies for collective minimalist mobile robots". Thesis, University of the West of England, Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265090.
6
de, Azevedo Ricardo. "Fully Decentralized Multi-Agent System for Optimal Microgrid Control". FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2461.
Abstract (sommario):
In preparation for the influx of renewable energy sources that will be added to the electrical system, flexible and adaptable control schemes are necessary to accommodate the changing infrastructure. Microgrids have been gaining much attention as the main solution to the challenges of distributed and intermittent generation, but due to their low inertia, they need fast-acting control systems in order to maintain stability. Multi-Agent Systems have been proposed as dynamic control and communication frameworks. Decentralized arrangements of agents can provide resiliency and the much-desired “plug and play” behavior. This thesis describes a control system that implements droop control and the diffusion communication scheme without the need of a centralized controller to coordinate the Microgrid agents to maintain the frequency and stable operating conditions of the system. Moreover, the inter-agent communication is unaffected by changing network configurations and can achieve optimal economic dispatch through distributed optimization.
7
Calabria, Mauro [Verfasser], e Walter [Akademischer Betreuer] Schumacher. "Modeling and distributed control of decentralized energy generation: a MIMO approach / Mauro Calabria ; Betreuer: Walter Schumacher". Braunschweig : Technische Universität Braunschweig, 2015. http://d-nb.info/1175819336/34.
8
Mundy, David H. "Decentralised control flow : a computational model for distributed systems". Thesis, University of Newcastle Upon Tyne, 1988. http://hdl.handle.net/10443/2050.
Abstract (sommario):
This thesis presents two sets of principles for the organisation of distributed computing systems. Details of models of computation based on these principles are together given, with proposals for programming languages based on each model of computation. The recursive control flow principles are based on the concept of recursive control flow computing system structuring. A recursive comprises a group of subordinate computing systems connected together by Each subordinate computing system may either be a communications medium. which a a computing system consists of a processing unit, memory some is itself a recursive component, and input/output devices, or computing components control flow system. The memory of all the computing systems within a recursive control flow computing subordinate system are arranged in a hierarchy. Using suitable addresses, any part of the hierarchy is accessible to any sequence of instructions which may be executed by the processing unit of a subordinate computing system. This rise to serious difficulties in the global accessibility gives understanding of programs written the meaning of in a programming language recursive control flow on the model of computation. based Reasoning about a particular program in isolation is difficult because of the potential interference between the execution different programs cannot be ignored . alternative principles, decentralised control flow, restrict the The accessibility of subordinate global the memory components of the computing The basis of the concept of objects forms the systems. principles. Information channels may flow along unnamed between instances of these objects, this being the only way in which one instance of an object may communicate with some other instance of an object. Reasoning particular program written in a programming language about a based on the decentralised control flow model of computation is easier since it is that there will be no interference between the guaranteed execution of different programs.
9
Veetaseveera, Jomphop. "Decentralized control design for synchronization of multi-agent systems with guaranteed individual costs". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0303.
Abstract (sommario):
Les travaux de cette thèse portent sur la synthèse et l'analyse d'algorithmes de synchronisation pour des systèmes multi-agents avec une dynamique linéaire. Par synchronisation, nous voulons que les états de tous les agents évoluent sur la même trajectoire à partir d'un certain temps. En prenant en compte des contraintes de communication, nous proposons des architectures de commandes décentralisées, c.-à-d. qui n'utilisent que des informations locales. Dans une première partie, nous nous inspirons de la théorie des jeux pour proposer une loi de commande considérant un coût individuel de satisfaction par agent. Afin de faciliter l'analyse, le problème de synchronisation est d'abord reformulé en un problème de stabilisation. Ensuite, des conditions données sous forme d'inégalités matricielles linéaires permettent de vérifier si un profil de gains correspond un équilibre de satisfaction ou non. Un ensemble de gains est un équilibre de satisfaction lorsque le coût individuel de chaque agent est borné par un seuil donné. La seconde partie consacrée aux réseaux avec des clusters, se base sur la théorie des systèmes singulièrement perturbés pour présenter une loi de commande plus axée sur des réseaux de grandes envergures. L'objectif est de fournir une méthode efficace en termes de calcul pour concevoir des stratégies de contrôle qui garantissent une certaine limite sur le coût de chaque cluster. En utilisant une méthode de séparation d'échelles de temps, la conception de la loi de commande est séparée en deux parties: une commande interne et une commande externe. Leurs conceptions se font indépendamment l'une de l'autre et tend à réduire les charges de calculs. De plus, nous montrons que la commande interne n'affecte le coût du cluster que pendant une courte période de tempsThe work of this thesis focuses on the synthesis and analysis of synchronization algorithms for multi-agent systems, with linear dynamics and fixed topology. By synchronization, we mean that the states of all agents evolve on the same trajectory from a certain time. Taking into account communication constraints, we propose decentralized control architectures, i.e. that use only local information. In a first part, we draw from game theory to propose a control law considering an individual satisfactory cost per agent. In order to facilitate the analysis, the synchronization problem is first reformulated as a stabilization problem. Then, conditions given in the form of Linear Matrix Inegalities allow to check if a gain profile corresponds to a satisfaction equilibrium or not. A set of gains is a satisfaction equilibrium when the individual cost of each agent is bounded by a given threshold. Furthermore, based on the output feedback control, a second result allows us to synthesize the gain of an agent assuming the gains of the other agents are known. The second part, dedicated to networks with clusters, is based on the Singular Perturbed Theory to present a control law more focused on large-scale networks. The objective is to provide a computationally efficient method to design control strategies that guarantee a certain limit on the cost of each cluster. Using a time-scale separation method, the control law design is separated into two parts: an internal and an external control. Their designs are done independently from each other and tend to reduce the computational load. Moreover, we show that the internal control affects the cost of the cluster only during a short period of time
10
Keppmann, Felix Leif [Verfasser], e R. [Akademischer Betreuer] Studer. "Decentralized Control and Adaptation in Distributed Applications via Web and Semantic Web Technologies / Felix Leif Keppmann ; Betreuer: R. Studer". Karlsruhe : KIT Scientific Publishing, 2020. http://d-nb.info/1207470260/34.
11
Cintuglu, Mehmet Hazar. "Wide-Area Time-Synchronized Closed-Loop Control of Power Systems And Decentralized Active Distribution Networks". FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/3031.
Abstract (sommario):
The rapidly expanding power system grid infrastructure and the need to reduce the occurrence of major blackouts and prevention or hardening of systems against cyber-attacks, have led to increased interest in the improved resilience of the electrical grid. Distributed and decentralized control have been widely applied to computer science research. However, for power system applications, the real-time application of decentralized and distributed control algorithms introduce several challenges. In this dissertation, new algorithms and methods for decentralized control, protection and energy management of Wide Area Monitoring, Protection and Control (WAMPAC) and the Active Distribution Network (ADN) are developed to improve the resiliency of the power system. To evaluate the findings of this dissertation, a laboratory-scale integrated Wide WAMPAC and ADN control platform was designed and implemented. The developed platform consists of phasor measurement units (PMU), intelligent electronic devices (IED) and programmable logic controllers (PLC). On top of the designed hardware control platform, a multi-agent cyber-physical interoperability viii framework was developed for real-time verification of the developed decentralized and distributed algorithms using local wireless and Internet-based cloud communication. A novel real-time multiagent system interoperability testbed was developed to enable utility independent private microgrids standardized interoperability framework and define behavioral models for expandability and plug-and-play operation. The state-of-theart power system multiagent framework is improved by providing specific attributes and a deliberative behavior modeling capability. The proposed multi-agent framework is validated in a laboratory based testbed involving developed intelligent electronic device prototypes and actual microgrid setups. Experimental results are demonstrated for both decentralized and distributed control approaches. A new adaptive real-time protection and remedial action scheme (RAS) method using agent-based distributed communication was developed for autonomous hybrid AC/DC microgrids to increase resiliency and continuous operability after fault conditions. Unlike the conventional consecutive time delay-based overcurrent protection schemes, the developed technique defines a selectivity mechanism considering the RAS of the microgrid after fault instant based on feeder characteristics and the location of the IEDs. The experimental results showed a significant improvement in terms of resiliency of microgrids through protection using agent-based distributed communication.
12
Lin, Wei. "Differential Games for Multi-Agent Systems under Distributed Information". Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5973.
Abstract (sommario):
In this dissertation, we consider differential games for multi-agent systems under distributed information where every agent is only able to acquire information about the others according to a directed information graph of local communication/sensor networks. Such games arise naturally from many applications including mobile robot coordination, power system optimization, multi-player pursuit-evasion games, etc. Since the admissible strategy of each agent has to conform to the information graph constraint, the conventional game strategy design approaches based upon Riccati equation(s) are not applicable because all the agents are required to have the information of the entire system. Accordingly, the game strategy design under distributed information is commonly known to be challenging. Toward this end, we propose novel open-loop and feedback game strategy design approaches for Nash equilibrium and noninferior solutions with a focus on linear quadratic differential games. For the open-loop design, approximate Nash/noninferior game strategies are proposed by integrating distributed state estimation into the open-loop global-information Nash/noninferior strategies such that, without global information, the distributed game strategies can be made arbitrarily close to and asymptotically converge over time to the global-information strategies. For the feedback design, we propose the best achievable performance indices based approach under which the distributed strategies form a Nash equilibrium or noninferior solution with respect to a set of performance indices that are the closest to the original indices. This approach overcomes two issues in the classical optimal output feedback approach: the simultaneous optimization and initial state dependence. The proposed open-loop and feedback design approaches are applied to an unmanned aerial vehicle formation control problem and a multi-pursuer single-evader differential game problem, respectively. Simulation results of several scenarios are presented for illustration.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
13
Gong, Kuangye [Verfasser], Ulrich [Akademischer Betreuer] Konigorski e Jutta [Akademischer Betreuer] Hanson. "A Concept of Distributed Energy Management Systems with Fully Decentralized Primary Control Strategies for Microgrids / Kuangye Gong ; Ulrich Konigorski, Jutta Hanson". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2018. http://d-nb.info/1166851087/34.
14
Rai, Anurag. "Analysis and Design Tools for Structured Feedback Systems". BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3270.
Abstract (sommario):
As we begin to analyze and construct extremely complex systems, a theory for understanding and designing the underlying architecture becomes very important. To move in the direction of a precise theory of architecture, this thesis will provide some concrete tools to analyze and design complex systems with a given network structure. The first main result of this thesis analyzes the vulnerability of a system and shows that a system's vulnerability depends on its network structure. We will consider destabilization attacks acting on a single link in a system's logical interconnection structure. The concept of a vulnerable link is characterized and necessary and sufficient conditions for identifying these links are provided. The vulnerability of various system architectures are then characterized by the vulnerability of their weakest link, and it is shown that every transfer function has a completely secure architecture with no vulnerable links. The second part of this thesis focuses on synthesizing controllers with a specified network structure. It presents a new approach to distributed controller design that exploits the dynamical structure function representation of linear time invariant systems to characterize the structure of a system. The design technique sequentially constructs each link in an arbitrary controller signal structure, and the main theorem proves that either the resulting controller is stabilizing or that no controller with the desired structure can stabilize the system.
15
Moussa, Hassan. "Contribution to the Decentralized Energy Management of Autonomous AC-Microgrid". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0161/document.
Abstract (sommario):
Cette thèse porte sur des micro-réseaux AC isolées qui permettent l’intégration des ressources énergétiques distribuées (DER) pouvant fournir leur énergie d'alimentation existante de manière contrôlée pour assurer le bon fonctionnement global du système. L'interconnexion d'un DER à une micro-réseau s'effectue habituellement en utilisant un convertisseur d'interface distribué (DIC) (i.e. un bloc d'interface d'électronique de puissance générale) qui est constitué d’un module de convertisseur à l'entrée de la source, un onduleur de tension (VSI), un module d'interfaçage de sortie, et le module de commande. Dans cette thèse on réalise plusieurs lois de commande basées sur des méthodes décentralisées. L'accent principal est mis sur les fonctions "Droop" qui ont la tâche de maintenir un équilibre de distribution d'énergie entre les différentes sources énergétiques connectées à la micro-réseau. L'objectif est d'assurer la stabilité du système et d’améliorer les performances dynamiques en partageant la puissance entre les différents générateurs d’électricité distribués (DGs) en fonction de leur puissance nominale. Le développement d'une analyse de stabilité en boucle fermée s’avère utile pour étudier la dynamique du système afin d'obtenir une réponse transitoire souhaitée qui permet d'identifier les paramètres de contrôle de boucle appropriés. L'amélioration de la qualité d’énergie des micro-réseaux est également un objectif de cette thèse. La réduction des distorsions harmoniques de la tension de sortie en présence de charges linéaires et non linéaires est prise en compte dans nos travaux. D'autres aspects seront étudiés sur la façon de traiter les charges constantes connectées au réseau et les grandes perturbations qu’ils produisent. Cela donne lieu à d'autres études de recherche portant sur la stabilité grand signal des micro-réseauxThis thesis deals with islanded AC microgrid that allows any integration of Distributed Energy Resources (DERs) that may provide their existing supply energy in a controlled manner to insure overall system functioning. The interconnection of a DER to a microgrid is done usually by using a Distributed Interface Converter (DIC), a general power electronics interface block, which consists of a source input converter module, a Voltage Source Inverter module (VSI), an output interface module, and the controller module. The thesis realizes several control laws based on decentralized methods. The major focus is on the Droop functions that are responsible for providing a power distribution balance between different Energy Resources connected to a microgrid. The aim is to insure system stability and better dynamic performance when sharing the power between different DGs as function to their nominal power. Developing a closed loop stability analysis is useful for studying system dynamics in order to obtain a desired transient response that allows identifying the proper loop control parameters. Power Quality enhancement in microgrids is also a purpose of this research. The reduction of harmonic distortions of the output voltage when supplying linear and non-linear loads are taken in consideration in this thesis. Further aspects will be studied about how to deal with constant power loads connected to the grid and the large perturbations exerted. This results to further research studies that deal with large-signal stability of microgrids
16
Moussa, Hassan. "Contribution to the Decentralized Energy Management of Autonomous AC-Microgrid". Electronic Thesis or Diss., Université de Lorraine, 2017. http://www.theses.fr/2017LORR0161.
Abstract (sommario):
Cette thèse porte sur des micro-réseaux AC isolées qui permettent l’intégration des ressources énergétiques distribuées (DER) pouvant fournir leur énergie d'alimentation existante de manière contrôlée pour assurer le bon fonctionnement global du système. L'interconnexion d'un DER à une micro-réseau s'effectue habituellement en utilisant un convertisseur d'interface distribué (DIC) (i.e. un bloc d'interface d'électronique de puissance générale) qui est constitué d’un module de convertisseur à l'entrée de la source, un onduleur de tension (VSI), un module d'interfaçage de sortie, et le module de commande. Dans cette thèse on réalise plusieurs lois de commande basées sur des méthodes décentralisées. L'accent principal est mis sur les fonctions "Droop" qui ont la tâche de maintenir un équilibre de distribution d'énergie entre les différentes sources énergétiques connectées à la micro-réseau. L'objectif est d'assurer la stabilité du système et d’améliorer les performances dynamiques en partageant la puissance entre les différents générateurs d’électricité distribués (DGs) en fonction de leur puissance nominale. Le développement d'une analyse de stabilité en boucle fermée s’avère utile pour étudier la dynamique du système afin d'obtenir une réponse transitoire souhaitée qui permet d'identifier les paramètres de contrôle de boucle appropriés. L'amélioration de la qualité d’énergie des micro-réseaux est également un objectif de cette thèse. La réduction des distorsions harmoniques de la tension de sortie en présence de charges linéaires et non linéaires est prise en compte dans nos travaux. D'autres aspects seront étudiés sur la façon de traiter les charges constantes connectées au réseau et les grandes perturbations qu’ils produisent. Cela donne lieu à d'autres études de recherche portant sur la stabilité grand signal des micro-réseauxThis thesis deals with islanded AC microgrid that allows any integration of Distributed Energy Resources (DERs) that may provide their existing supply energy in a controlled manner to insure overall system functioning. The interconnection of a DER to a microgrid is done usually by using a Distributed Interface Converter (DIC), a general power electronics interface block, which consists of a source input converter module, a Voltage Source Inverter module (VSI), an output interface module, and the controller module. The thesis realizes several control laws based on decentralized methods. The major focus is on the Droop functions that are responsible for providing a power distribution balance between different Energy Resources connected to a microgrid. The aim is to insure system stability and better dynamic performance when sharing the power between different DGs as function to their nominal power. Developing a closed loop stability analysis is useful for studying system dynamics in order to obtain a desired transient response that allows identifying the proper loop control parameters. Power Quality enhancement in microgrids is also a purpose of this research. The reduction of harmonic distortions of the output voltage when supplying linear and non-linear loads are taken in consideration in this thesis. Further aspects will be studied about how to deal with constant power loads connected to the grid and the large perturbations exerted. This results to further research studies that deal with large-signal stability of microgrids
17
Feltrin, Francesco. "Design and Testing of Clustered Components For Modular Spacecraft Architectures". Doctoral thesis, Università degli studi di Padova, 2020. http://hdl.handle.net/11577/3425903.
Abstract (sommario):
In recent years, the space industry has demonstrated a renewed interest in multi agent systems, from the deployment of large and mega constellations to the plans to test Federated and in orbit assembly concepts. Furthermore, as the CubeSat platform has become a de-facto standard able to support ambitious missions, the cost for multi agent systems has decreased significantly.
The aim of this work is to study the benefits and drawbacks of large multi agent systems which might result from in-space assembly of numerous small autonomous spacecraft.
The thesis is divided into two parts; in the first we focus on how to efficiently and reliably control large clusters of actuators spread across a modular assembly. We examine both classical centralized and decentralized methods to solve the allocation of tasks within the clusters and finally propose a novel method, for which we provide proof of convergence and optimality. To characterize it, we simulate a large cluster of reaction wheels using data obtained from a hardware prototype. Compared to traditional methods, we observe reduced power consumption and more robust convergence when applied to large numbers of actuators. Finally, we generalize the model to encompass multiple inputs-multiple outputs systems. While multiple outputs can easily be accounted for, considering multiple inputs has revealed to be very challenging and only weak results are presented.
The second part is devoted to exploiting cluster properties during the preliminary design, leveraging both technological features and analytical conditions to improve design optimization methods. Building on the capabilities developed in the first part, namely the existence of an effective method to coordinate large number of actuators reliably, we present an analytical framework to pursue system design and optimization. A long and dry section of the thesis is devoted to the mathematical characterization of the framework and to provide proofs for its main properties. The
abstract assumptions needed for the proposed algorithm are examined, and their validity assessed in the case of a CubeSat design procedure. Finally, a minimal computational implementation is described and applied to GOMX4-B mission.Il settore spaziale sta dimostrando un rinnovato interesse verso concetti basati sull’impiego di sistemi multi-agenti; dallo sviluppo di costellazioni con centinaia di satelliti (mega constellations) a test per architetture federate e dimostratori di assemblaggio in orbita. Inoltre, le piattaforme Cubesat sono ormai uno standard in grado di compiere missioni ambiziose, abbassando quindi il costo di sistemi multi agente. Questo lavoro si propone di studiare i benefici e gli svantaggi di sistemi composti da un grande numero di agenti, quali possono essere degli assemblati in orbita costituiti da innumerevoli satelliti autonomi. Questo documento é diviso in due parti; nella prima ci si concentra su come controllare in maniera affidabile agglomerati composti da un grande numero di attuatori distributi su satelliti diversi. Vengono considerati sia algoritmi centralizzati che decentralizzati per risolvere il problema di allocazione dei compiti; viene infine proposto un nuovo metodo, per il quale vengono fornite dimostrazioni di convergenza. Per caratterizzarne il comportamento, si simula un cluster di ruote di reazione, modellate usando dati ottenuti con un prototipo da laboratorio. In confronto a metodi classici, l’algoritmo proposto mostra un consumo di potenza inferiore e una convergenza piú robusta soprattutto per grandi numeri di attuatori. Infine, si generalizza il modello di attuatore per comprendere anche casi con molteplici input e output. Mentre il caso di molteplici output viene trattato facilmente e differisce di poco dal caso con output singolo, trattare input multipli si é rivelato piuttosto complesso; vengono presentati solo risultati deboli. La seconda parte é dedicata a sfruttare le proprietá dei cluster durante il design preliminare, facendo leva sia su caratteristiche tecnologiche che su proprietá formali per migliorare le procedure di ottimizzazione del desing. Mettendo a frutto i risultati ottenuti nella prima parte, ovvero la capacitá di coordinare in maniera efficace e affidabile un grande numero di attuatori, viene presentato un metodo analitico per l’ottimizzazione di sistema. Una lunga porzione della tesi viene dedicata a dimostrare le proprietá salienti del metodo. Le ipotesi necessarie per applicare il modello vengono esaminate per giudicarne la pretinenza nel caso di design di un cubesat. Infine, una implementazione computazionale viene descritta e applicata alla missione GOMX4-B.
18
Wei, Jin. "Modeling and Coordination of interconnected microgrids using distributed artificial intelligence approaches". Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCA021.
Abstract (sommario):
À mesure que les sources renouvelables pénètrent dans le système électrique actuel pour atténuer le réchauffement planétaire et la pénurie d’énergie, le concept de microréseau (MG) permet de réduire l’impact de la production intermittente sur le réseau de services publics. Il permet d'améliorer l’automatisation et l’intelligence du réseau électrique avec des caractéristiques plug-and-play. L’intégration d’un plus grand nombre de MG dans un réseau de distribution favorise le développement du réseau intelligent. Leur coordination pourrait conduire à une grande fiabilité du système avec un faible coût, et une forte résistance aux pannes électriques. La réalisation de ces profits repose sur des technologies développées de communication et de stratégies de contrôle.La répartition de la puissance dans les MG répartis tout en coordonnant les éléments au sein de chaque MG exige un contrôle décentralisé. L'approche multiagent permet de modéliser un réseau de MG comme un système physiquement distribué. Cette thèse étudie principalement le contrôle de coordination dans le réseau MG et sa modélisation à base d'agent.. L' objectif est de promouvoir la performance des contrôles en termes d’efficacité et de fiabilité. Deux méthodes sont envisagées pour permettre l’évolutivité du système, y compris la coordination avec les MG voisins et dans la zone de coordination étendue. Une plateforme de simulation est établie pour valider les approches proposées.Les stratégies de contrôle pour la coordination entre les MG et leurs voisins sont proposées afin de maintenir la charge complète et la sécurité tout en minimisant le coût de production. Le contrôle centralisé dans le groupe de coordination est appliqué à la gestion économique de l’énergie. Il utilise une méthode de Newton-Raphson pour répartir la puissance entre les MG voisins en simplifiant la relation entre le coût de production de MG et sa puissance de sortie. Une approche fondée sur le consensus est adoptée pour calculer le flux de puissance du réseau, et les résultats sont comparés avec la capacité maximale sur la ligne pour assurer un fonctionnement sûr. Pour améliorer encore les avantages économiques, l’approximation de la relation entre la puissance de production de MG et le coût de production est améliorée par une autre stratégie fondée sur la notion de marché. Il construit un marché pour le commerce d’électricité avec les voisins. Cette méthode préserve la vie privée de chaque MG. Le calcul du débit de puissance est simplifié pour être proportionnel à la différence d’angle entre les deux extrémités de la ligne de raccordement. Les deux stratégies sont testées sur plusieurs réseaux MG. Leur performance montre que les deux approches sont évolutives et pourraient économiquement compenser le manque d’approvisionnement en charge dans les MG défectueux.Pour la stratégie de contrôle avec une fiabilité et un profit plus élevés, une stratégie de coordination au sein d’une vaste zone sélectionnée de MG est proposée. L’élargissement de la zone de coordination en fonction des MG voisins fournit plus de sources d’énergie au MG. Il assure suffisamment de puissance pour compenser le déséquilibre et offre plus de choix pour la distribution de puissance. La sélection de la zone de coordination est réalisée par un algorithme évolutionnaire distribué. La programmation quadratique dans Gurobi est utilisée pour résoudre le problème de répartition de puissance. Un autre algorithme génétique est également adopté pour résoudre le problème de la répartition optimale de la puissance avec un coût de production quadratique pour la microturbine. La performance de cette stratégie est testée, et les résultats montrent qu’elle a des avantages en termes de fiabilité, d'évolutivité et de profit par rapport aux méthodes centraliséesAs renewable sources penetrate the current electrical system to relief global warming and energy shortage, microgrid (MG) emerges to reduce the impact of intermittent generation on the utility grid. Additionally, it improves the automation and intelligence of the power grid with plug-and-play characteristics. Inserting more MGs into a distribution network promotes the development of the smart grid. Thus MG networks existing in the power system are in prospect. Coordinating them could gain a system with high reliability, low cost, and strong resistance to electrical faults. Achieving these profits relies on developed technologies of communication, control strategy, and corresponding algorithms.Dispatching power in distributed MGs while coordinating elements within the individual MG demands a decentralized control system, in which the multi-agent system possesses advantages. It is applied to the MG network for establishing a physically distributed system. Based on the multi-agent system, this thesis mainly studies the coordination control in the MG network and its modeling. It aims at promoting control performance in terms of efficiency, reliability, economic benefit, and scalability. Two methods are considered to enable the system scalability, including the coordination with neighboring MGs and within the extensive coordinating area. A simulation platform is established to validate the proposed approaches.The control strategies for coordination between MGs and their neighbors are proposed to maintain the complete load supply and global security operation while minimizing the generation cost. Centralized control in the coordination group is applied for economic energy management. It uses a Newton-Raphson method to dispatch power among neighboring MGs by simplifying the relationship between MG generation cost and its output power. An average consensus approach is adopted to calculate the caused network power flow, and the results are compared with the maximal capacity on the line to keep safe operation. To further improve the economic benefits, the approximation of the relationship between MG output power and the caused generation cost is improved by an another strategy based on the market concept. It builds a market for neighboring power trade. This method maintains the operation privacy of individual MG. Power flow calculation is simplified to be proportional to the angle difference between the two terminates of the connecting line. Both strategies are tested on several MG network. Their performance shows that both approaches possess scalability and could economically compensate for the lack of load supply in faulted MG.For the control strategy with higher reliability and profit, a coordination strategy within a selected extensive area of MGs is proposed. Expanding the coordination area based on neighboring MGs provides more energy sources to the demanded MG. It ensures enough power to compensate imbalance and offers more choices for power dispatching. The selection of the coordination area is based on a distributed evolutionary algorithm. Quadratic programming in Gurobi is used to solve the power dispatching problem. Another genetic algorithm is also adopted to solve the problem of optimal power dispatching with a quadratic generation cost for microturbine. The performance of this strategy is tested, and the results show that it has comprehensive advantages on reliability, scalability, and profit compared with centralized methods
19
RUGGERI, SIMONA. "Centralised and decentralised control of active distribution systems: models, algorithms and applications". Doctoral thesis, Università degli Studi di Cagliari, 2015. http://hdl.handle.net/11584/266574.
Abstract (sommario):
Power system were traditionally planned and designed by assuming unidirectional power flows from power stations to loads. Nowadays, several factors (e.g., liberalization of the electricity market, need of increased reliability, and environmental issues) lead to a situation where electricity is produced also downstream the transmission level. Connecting generators to the distribution networks could provide several benefits to the whole system, but also technical and safety problems that must be faced. On the other hand, the loads are changing: new loads like electric vehicles and electric pumps are appearing in the network and they are going to modify the electricity consumption; while traditional loads are designed in order to be more efficient, but with additional functions or special features that require more energy.
For all these reasons, since 2005, the interest on Smart Grid (electricity network that can intelligently integrate the actions of all users connected to it – generators, consumers – in order to efficiently deliver sustainable, economic and secure electricity supplies) increased.
In this framework different techniques to control, operate and thereby integrate distributed energy resources into the network have been analysed and developed. The first technique designed is a centralised control, characterised by a central controller (Distribution Management System) that gathers information like the measures of the main electric parameters, energy price and indicates to DERs (Active Loads, Generators, Energy Storage) the optimal set points minimizing the system cost, subject to technical and economical constraints. The second technique developed is a decentralised control using Multi Agent Systems (MAS). This type of control has been designed and developed for the direct control of active demand and plug-in electric vehicles, managed by the Aggregator, entrusted by the end users to change their consumption habits according to their needs. Moreover, the proposed decentralised MAS, with the active participation of small consumers in the electricity system, support the integration of the Electric Vehicles in the LV distribution network and reduce its harmful impact on voltage regulation.
The techniques and the algorithms proposed by the author are analysed and applied in representative Italian Distribution networks, by taking into account the development of the distribution system according to the load profile evolution, providing several examples to underline the importance of the Active Management for deferring the reinforcement of the existing grid infrastructures, increasing the hosting capacity of the network
20
Xiao, Zijian. "Contrôle modulaire décentralisé - Application aux convertisseurs multi-phasés isolés entrelacés et magnétiquement couplés". Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/10717/1/xiao.pdf.
Abstract (sommario):
Le domaine de la conversion d’énergie requiert, la plupart du temps, la mise en œuvre d’études spécifiques et coûteuses pour répondre, avec les meilleures performances possibles (rendement, compacité, CEM), aux diverses applications. Afin de proposer une solution générique et évolutive, nous nous sommes intéressés à l’utilisation d’un réseau de micro-convertisseurs optimisés, de faible puissance, que l’on peut associer en série et/ou en parallèle, pour couvrir un large domaine d’applications. Dans ces conditions, un effort unique de réflexion est à porter sur le dimensionnement d’un micro-convertisseur optimisé qui joue le rôle de cellule élémentaire ou de brique de base pour l’établissement du réseau complet. Cependant, cela suppose de mettre en œuvre également une méthode de contrôle adaptée au grand nombre de micro-convertisseurs ainsi qu’une technique de communication entre tous les micro-convertisseurs, pour assurer un bon équilibrage de la puissance. L'objectif principal de cette thèse est de fournir une solution intégrée pour le contrôle à la fois des cellules de commutation internes du micro-convertisseur et du réseau lui-même. Pour y parvenir, une solution modulaire de contrôle entièrement décentralisé est proposée. Trois étapes essentielles sont alors étudiées : la génération des porteuses entrelacées, l’équilibrage des courants de phase et la régulation des grandeurs de sortie courant et/ou tension. Ces trois étapes sont abordées de manière à proposer une solution entièrement décentralisée. Plusieurs cartes de test ont été réalisées pour valider chaque fonction indépendamment. Un circuit intégré (démonstrateur), implémentant l’ensemble des fonctions nécessaires au contrôle d’un micro-convertisseur 5V-2A-1MHz, a également été conçu et testé. Les résultats expérimentaux montrent clairement la validité des solutions proposées, ce qui ouvre la voie vers un contrôle mieux adapté aux nouveaux types d’architectures multi-phasées et distribuées en réseau.
21
Grape, Felix. "Designing an Access Control System for Internet of Things". Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217507.
Abstract (sommario):
For many Internet of Things (IoT) devices security have not been a priority during the development, but what happens if the makers of IoT devices use a secure framework for developing their devices? In this thesis a number of such frameworks have been evaluated for their suitability to build an access control system around. Both Vanadium and Protocol of Things (PoT) were found to be suitable candidates. Both frameworks employ a distributed access control model where the owner of a device can grant other users access to the device by generating a signed authorization. PoT was ultimately chosen as the framework around which to design the prototype access control system because it was deemed to be slightly more suitable than Vanadium. The prototype takes the rule based and discretionary access control model from the underlying framework and makes it possible for administrators to transparently authorize users to devices through role abstractions. Thus it is possible to transparently manage a class of users at the same time instead of having to manage each individual user. Furthermore the prototype is able to do this in a generic way. The prototype does not contain any code of functionality for any specific device it manages, it is capable of managing access to any PoT device. The design and implementation is deemed both scalable and efficient. Running on a single thread it is possible to generate over one thousand signed authorizations per second. In a system where users are granted access to 200 unique device permissions the total file size of the signed authorizations and accompanying meta data does not exceed 150 kB. It takes approximately 70 ms to establish a secure connection between the client and server software. For large data transfers the throughput is approximately 2.6-2.8 MB per second, including encryption and decryption of request and response from the client to the server.För många enheter tillhörande sakernas internet har säkerhet inte varit en prioritet under utvecklingen, men vad händer om tillverkare istället använder ett säkert ramverk för att utveckla sina produkter? I den här rapporten presenteras en utvärdering av några sådana ramverks lämplighet för att användas för att bygga ett accesskontrollsystem kring. Både Vanadium och Protocol of Things (PoT) finns vara lämpliga kandidater. Båda ramverken använder en decentraliserad säkerhetsmodell där ägaren av en enhet kan ge andra användare tillgång till enheten genom att generera en signerad auktorisation. PoT är det ramverk som användes för att utforma accesskontrollsystemprototypen kring för att det ansågs vara något mer lämpligt jämfört med Vanadium. Prototypen använder en rollabstraktion för att underlätta arbetet för administratörer att ge användare rätt behörigheter. På så vis blir det möjligt att konfigurera en klass av användare samtidigt istället för att behöva konfigurera varje användare individuellt. Prototypen kan göra allt detta på ett generiskt sätt. Det innebär att prototypen inte innehåller någon kod eller funktionalitet som är specifik för någon enhet så länge det är en PoT-enhet. Den föreslagna designen och implementationen är skalbar och effektiv. Över ett tusen signerade auktorisationer kan genereras per sekund på en exekveringstråd. I ett system där användare ges behörighet till 200 unika behörigheter på olika enheter uppgår den totala filstorleken för de signerade auktorisationerna och tillhörande metadata till mindre än 150 kB. Det tar uppskattningsvis 70 ms att skapa en säker anslutning mellan klient- och server-mjukvara. För stora dataöverföringar är överföringshastigheten uppskattningsvis 2.6-2.8 MB per sekund, vilket inkluderar kryptering och avkryptering av fråga och svar från klienten till servern.
22
Bastos, Renan Fernandes. "Sistema de gerenciamento para a integração em CC de fontes alternativas de energia e armazenadores híbridos conectados a rede de distribuição via conversores eletrônicos". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-25012017-161639/.
Abstract (sommario):
Esta tese de doutorado visa o estudo e o desenvolvimento de topologias e técnicas de controle para a integração de fontes alternativas tais como, solar e eólica acopladas a um barramento comum em corrente continua (CC) e conectá-las à rede de distribuição. O sistema contará também com elementos armazenadores como bancos de baterias e ultracapacitores, formando assim uma estrutura híbrida de armazenamento. Algoritmos de gerenciamento de energia serão implementados para que o perfil de injeção de potência na rede seja suave, eliminando as oscilações que são criadas, naturalmente, por fontes dependentes de fatores climáticos. Como consequência, os sistemas formados por fontes alternativas podem se tornar confiáveis e previsíveis, melhorando a capacidade de planejamento em um cenário cujos sistemas apresentem uma participação elevada na matriz energética. Duas metodologias de gerenciamento de energia são executadas neste trabalho, na primeira o ultracapacitor é gerenciado de modo a permitir a transferência de potência constante para a rede de distribuição em intervalos da ordem de minutos. A segunda estratégia se baseia no uso de banco de baterias combinado com ultracapacitores, formando uma estrutura híbrida de armazenamento. Nessa estrutura de gerenciamento, os armazenadores se comunicam entre si de forma a realizar um compartilhamento e filtragem de energia, fazendo com que transitórios de potência não sejam transmitidos para a rede de distribuição. Nesta estratégia, as baterias são responsáveis pelo fornecimento/absorção da potência média enquanto os ultracapacitores se encarregam dos transitórios. No segundo instante outras duas metodologias de divisão de carga são propostas para microrredes híbridas, contudo são baseadas em estratégias descentralizadas, ou seja, os armazenadores não se comunicam entre si para realizar o compartilhamento. Resultados experimentais e simulações irão comprovar a efetividade das metodologias de gerenciamento propostas.This Ph.D. dissertation aims the study and development of topologies and control techniques to integrate various alternative sources such as solar and wind, coupled to a direct current (DC) common bus and connect them to the distribution grid. Storage devices such as battery banks and ultracapacitors will form a hybrid storage structure that is responsible for the power supplying in periods in which the sources are unable (times of the day in which the light incidence is low or when the wind amount is scarce). Power management algorithms will be implemented so the alternative sources and storage devices exchange energy, in order to make smoother the power injection profile in the grid, eliminating the fluctuations that are created naturally by alternative sources. With a smooth power profile, energy management systems based on alternative sources may become more reliable and predictable, improving planning capacity in a scenario in which the renewable energy sources have a high penetration in the energy matrix. To obtain such a result, two power management methodologies are executed; the first one is based on ultracapacitors and aims to deliver constant power to the distribution network, even when the power production is zero. However, this technique allows constant power just for a few minutes, once the ultracapacitor capacity is limited. The second strategy is based on the bank of batteries combined with ultracapacitors, forming the hybrid storage system. In this management structure, the storage devices communicate with each other in order to perform a power sharing, resulting in a filtrated power profile delivered to the distribution network. In this strategy, the batteries are responsible to providing average power while ultracapacitors are in-charge of the transient power, sparing the batteries from supplying power peaks. In a second moment, two other load sharing methodologies are proposed for hybrid systems, but are based on decentralized techniques, i.e. storage devices do not communicate with each other to make the power sharing. Experimental and simulated results will prove the effectiveness of the control strategies and management methodologies.
23
Hwang, Chan-Soo. "Decentralized communications using distributed state information /". May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
24
Nayak, Amiyaranjan Carleton University Dissertation Computer Science. "Decentralized management of distributed file systems". Ottawa, 1985.
25
Doyon, Michel. "Decentralized impedance control". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26384.
Abstract (sommario):
Many applications of manipulators to date have been based on position control, but when a robot manipulator makes contact with the environment, the control of force and position is required. One approach, impedance control, is to control the manipulator such that the relationship between position and force is well defined. For example, such that the robot behaves like a mass-spring-damper system whose parameters can be specified arbitrarily. In the recent years, many of the impedance control implementations were using force feedback from an end-effector force sensor and the impedance control was performed by forming the error in Cartesian coordinates. The implementation proposed here requires instead co-located torque sensors and the feedback control signals are based solely on joint variables, torque and displacement. Co-located torque sensors lead to a larger control bandwidth since the structural dynamics of the arm is seen as a perturbation, but is not part of the plant to be controlled. Simple SISO controllers, designed to modulate individual joint impedances, can achieve diagonal (decoupled) impedance matrices in Cartesian coordinates, provided that a set of SISO compensators, called her "decouplers", are set up to cancel the non-linear coupling among the joints. This strategy results in a simple computational architecture which does not require complex coordinates transformations to be performed at servo rate. The method can be used with non-redundant and redundant manipulators and experimental results are discussed using a seven DOF manipulator available at the Institut de recherche d'Hydro-Quebec.
26
Benelallam, Amine. "Model transformation on distributed platforms : decentralized persistence and distributed processing". Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0288/document.
Abstract (sommario):
Grâce à sa promesse de réduire les efforts de développement et maintenance du logiciel, l’Ingénierie Dirigée par les Modèles (IDM) attire de plus en plus les acteurs industriels. En effet, elle a été adoptée avec succès dans plusieurs domaines tels que le génie civil, l’industrie automobile et la modernisation de logiciels.Toutefois, la taille croissante des modèles utilisés nécessite de concevoir des solutions passant à l’échelle afin de les traiter (transformer), et stocker (persister) de manière efficace. Une façon de pallier cette problématique est d’utiliser les systèmes et les bases de données répartis. D’une part, les paradigmes de programmation distribuée tels que MapReduce et Pregel peuvent simplifier la distribution de transformations des modèles (TM). Et d’autre part, l’avènement des base de données NoSQL permet le stockage efficace des modèles d’une manière distribuée. Dans le cadre de cette thèse, nous proposons une approche pour la transformation ainsi que pour la persistance de grands modèles.Nous nous basons d’un côté, sur le haut niveau d’abstraction fourni par les langages déclaratifs (relationnels) de transformation et d’un autre côté, sur la sémantique bien définie des paradigmes existants de programmation distribués, afin de livrer un moteur distribué de TM. La distribution est implicite et la syntaxe du langage n’est pas modifiée (aucune primitive de parallélisation n’est ajoutée). Nous étendons cette solution avec un algorithme efficace de distribution de modèles qui se base sur l’analyse statique des transformations et sur résultats récents sur le partitionnement équilibré des graphes. Nous avons appliqué notre approche à ATL, un langage relationnel de TM et MapReduce, un paradigme de programmation distribué. Finalement, nous proposons une solution pour stocker des modèles à l’aide de bases de données NoSQL, en particulier au travers d’un cadre d’applications de persistance répartieModel-Driven Engineering (MDE) is gaining ground in industrial environments, thanks to its promise of lowering software development and maintenance effort. It has been adopted with success in producing software for several domains like civil engineering, car manufacturing and modernization of legacy software systems. As the models that need to be handled in model-driven engineering grow in scale, it became necessary to design scalable algorithms for model transformation (MT) as well as well-suitable persistence frameworks. One way to cope with these issues is to exploit the wide availability of distributed clusters in the Cloud for the distributed execution of model transformations and their persistence. On one hand, programming models such as MapReduce and Pregel may simplify the development of distributed model transformations. On the other hand, the availability of different categories of NoSQL databases may help to store efficiently the models. However, because of the dense interconnectivity of models and the complexity of transformation logics, scalability in distributed model processing is challenging. In this thesis, we propose our approach for scalable model transformation and persistence. We exploit the high-level of abstraction of relational MT languages and the well-defined semantics of existing distributed programming models to provide a relational model transformation engine with implicit distributed execution. The syntax of the MT language is not modified and no primitive for distribution is added. Hence developers are not required to have any acquaintance with distributed programming.We extend this approach with an efficient model distribution algorithm, based on the analysis of relational model transformation and recent results on balanced partitioning of streaming graphs. We applied our approach to a popular MT language, ATL, on top of a well-known distributed programming model, MapReduce. Finally, we propose a multi-persistence backend for manipulating and storing models in NoSQL databases according to the modeling scenario. Especially, we focus on decentralized model persistence for distributed model transformations
27
Wallin, Fredrik. "Distributed Communication for Streetlight Systems : A decentralized solution". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191133.
Abstract (sommario):
Streetlights are usually lit during all dark hours even though vehicles or other objects are not using the road. Instead of wasting energy on keeping the streetlights lit when no vehicles are using the road, the streetlights should be lit whenever vehicles are in proximity of the streetlights and turned off otherwise. A distributed network can be used to handle the communication between streetlights for sharing information about vehicles in proximity. There are streetlight systems that adapt from the environment and handles communication but are still not optimized for country roads with low frequency of vehicles. Therefore, distributed communication for streetlight systems is implemented, by letting the streetlights be a part of a distributed system. Each streetlight is represented with a Zolertia RE-Mote, a sensor for detecting objects and an LED. The representation of the streetlights are wirelessly connected as a mesh network where they can communicate with each other and forward data packets to nodes more far away in the network. The concept of having the streetlights in a distributed system is believed to work and can be considered to be applied on streetlights at country roads to save energy.Gatlyktor är oftast tända under alla timmar då det är mörkt ute, även fast det inte är något fordon eller annat objekt som använder vägen. Istället för att slösa energi på att ha gatlyktorna tända när det inte är några fordon som använder vägen, bör gatlyktorna vara tända när fordon är i närheten av dem och släckta annars. Ett distribuerat nätverk kan användas för att hantera kommunikationen mellan gatlyktor till att dela information om fordon i närheten. Det finns gatlyktsystem som anpassar efter miljön och hanterar kommunikationen, men är inte optimerat för landsvägar med låg trafik. Därför är distribuerad kommunikation för gatlyktsystem implementerat genom att låta gatlyktorna vara en del av ett distribuerat system. Varje gatlykta är representerad med en Zolertia RE-Mote, en sensor för detektering av objekt och en LED. Representationen är trådlöst kopplat som ett meshnätverk där de kan kommunicera med varandra och skicka vidare datapaket till noder längre bort i nätverket. Konceptet att ha gatlyktorna i ett distribuerat system tros fungera och kan tänkas att appliceras på gatlyktor på landsvägar för att spara energi.
28
Arndt, Natanael. "Distributed Collaboration on Versioned Decentralized RDF Knowledge Bases". Open-Access Hochschulverlag, 2021. https://htwk-leipzig.qucosa.de/id/qucosa%3A75258.
Abstract (sommario):
Ziel dieser Arbeit ist es, die Entwicklung von RDF-Wissensbasen in verteilten kollaborativen Szenarien zu unterstützen. In dieser Arbeit wird eine neue Methodik für verteiltes kollaboratives Knowledge Engineering – „Quit“ – vorgestellt. Sie geht davon aus, dass es notwendig ist, während des gesamten Kooperationsprozesses Dissens auszudrücken und individuelle Arbeitsbereiche für jeden Mitarbeiter bereitzustellen. Der Ansatz ist von der Git-Methodik zum kooperativen Software Engineering inspiriert und basiert auf dieser. Die Analyse des Standes der Technik zeigt, dass kein System die Git-Methodik konsequent auf das Knowledge Engineering überträgt. Die Hauptmerkmale der Quit-Methodik sind unabhängige Arbeitsbereiche für jeden Benutzer und ein gemeinsamer verteilter Arbeitsbereich für die Zusammenarbeit. Während des gesamten Kollaborationsprozesses spielt die Data-Provenance eine wichtige Rolle. Zur Unterstützung der Methodik ist der Quit-Stack als eine Sammlung von Microservices implementiert, die es ermöglichen, die Semantic-Web-Datenstruktur und Standardschnittstellen in den verteilten Kollaborationsprozess zu integrieren. Zur Ergänzung der verteilten Datenerstellung werden geeignete Methoden zur Unterstützung des Datenverwaltungsprozesses erforscht. Diese Managementprozesse sind insbesondere die Erstellung und das Bearbeiten von Daten sowie die Publikation und Exploration von Daten. Die Anwendung der Methodik wird in verschiedenen Anwendungsfällen für die verteilte Zusammenarbeit an Organisationsdaten und an Forschungsdaten gezeigt. Weiterhin wird die Implementierung quantitativ mit ähnlichen Arbeiten verglichen. Abschließend lässt sich feststellen, dass der konsequente Ansatz der Quit-Methodik ein breites Spektrum von Szenarien zum verteilten Knowledge Engineering im Semantic Web ermöglicht.:Preface by Thomas Riechert
Preface by Cesare Pautasso
1 Introduction
2 Preliminaries
3 State of the Art
4 The Quit Methodology
5 The Quit Stack
6 Data Creation and Authoring
7 Publication and Exploration
8 Application and Evaluation
9 Conclusion and Future Work
Bibliography
Web References
List of Figures
List of Tables
List of Listings
List of Definitions and Acronyms
List of Namespace PrefixesThe aim of this thesis is to support the development of RDF knowledge bases in a distributed collaborative setup. In this thesis, a new methodology for distributed collaborative knowledge engineering – called Quit – is presented. It follows the premise that it is necessary to express dissent throughout a collaboration process and to provide individual workspaces for each collaborator. The approach is inspired by and based on the Git methodology for collaboration in software engineering. The state-of-the-art analysis shows that no system is consequently transferring the Git methodology to knowledge engineering. The key features of the Quit methodology are independent workspaces for each user and a shared distributed workspace for the collaboration. Throughout the whole collaboration process data provenance plays an important role. To support the methodology the Quit Stack is implemented as a collection of microservices, that allow to integrate the Semantic Web data structure and standard interfaces with the distributed collaborative process. To complement the distributed data authoring, appropriate methods to support the data management process are researched. These management processes are in particular the creation and authoring of data as well as the publication and exploration of data. The application of the methodology is shown in various use cases for the distributed collaboration on organizational data and on research data. Further, the implementation is quantitatively compared to the related work. Finally, it can be concluded that the consequent approach followed by the Quit methodology enables a wide range of distributed Semantic Web knowledge engineering scenarios.:Preface by Thomas Riechert Preface by Cesare Pautasso 1 Introduction 2 Preliminaries 3 State of the Art 4 The Quit Methodology 5 The Quit Stack 6 Data Creation and Authoring 7 Publication and Exploration 8 Application and Evaluation 9 Conclusion and Future Work Bibliography Web References List of Figures List of Tables List of Listings List of Definitions and Acronyms List of Namespace Prefixes
29
Klingner, John. "Distributed and Decentralized Algorithms for Functional Programmable Matter". Thesis, University of Colorado at Boulder, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10980638.
Abstract (sommario):
Programmable matter is made up of large quantities of particles that can sense, actuate, communicate, and compute. Motivated to imbue these materials with functionality, this thesis presents algorithmic and hardware developments to meet the unique challenges presented by large-scale robot collectives. The quantity of robots involved necessitates algorithms and processes which scale—in terms of required communication, computation, and memory—sub-linearly to the number of robots, if scaling at all can not be avoided. Included are methods for communication, movement, synchronization, and localization. To encourage application to a variety of hardware platforms, the theoretical underpinnings of these contributions are made as abstract as possible. These methods are tested experimentally with real hardware, using the Droplet swarm robotics platform I have developed. I also present abstractions which relate global performance properties of a functional object composed of programmable matter to local properties of the hardware platform from which the object is composed. This thesis is further supported by example implementations of functional objects on the Droplets: a TV remote control, a pong game, and a keyboard with mouse.
30
Amazouz, Achour. "Optimal control for decentralized platooning". Thesis, KTH, Reglerteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121541.
Abstract (sommario):
The idea of autonomous vehicles and automated highway systems is no new concept to the automotive industry. The potential benets of such a technology are numerous. The platooning approach would imply energy economy through air drag reduction, but also reduced trac congestion and increased safety. The question of longitudinal control in a platoon conguration is central, the main concern being relative to safety. In this thesis, dierent classical control approaches will be compared and applied to the platooning problem. Among these approaches, one was tested in November 2012 in a demonstration which involved three teams and multiple vehicles from dierent Swedish universities. Constrained optimal control comes with the prospect of increased safety and better handling of some characteristics of physical systems. The main negative impact of this constraint handling lies in its computational complexity. Numerical problems were encountered and described with the use of MPC. Proportional-Integral and Linear Quadratic controllers were retained and applied to the tracking problem in the context of vehicle platooning. These methods will be compared in a simulation environment.
31
Hidell, Markus. "Decentralized Modular Router Architectures". Doctoral thesis, Stockholm : Laboratory for Communications Networks, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4090.
32
Alizadeh, Morteza. "Blockchain and Distributed Hash Table Technology in Decentralized Systems". Licentiate thesis, Luleå tekniska universitet, Datavetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86795.
Abstract (sommario):
The Internet of Things (IoT) is one of the popular domains in real-time analytics, ma-chine learning, ubiquitous computing, commodity sensors, and embedded systems where remote smart devices play notable roles in smart homes and industry. The information from emerging IoT environments like remotely-controlled objects, autonomous vehicles (AVs), and energy management can produce a huge amount of data. Moreover, under-standing the security in a scalable decentralized IoT environment is a significant issue.Decentralization has become popular again in the world since cryptocurrencies started to be a part of businesses. Therefore, researchers invested in upgrading resources to increase the reliability of these systems among people when most of the activities and human works are now managed by smart electronic devices remotely. Distributed ledgers, Distributed Hash Tables (DHTs), and blockchain technologies are proper decentralized technologies that improve system security, scalability, and trustworthiness. Blockchains contain a group of connected blocks that are digitally signed transactions stored in a decentralized fashion. The DHT technology is another decentralized solution that helps applications keep files and information immutable in a decentralized manner to mitigate the high cost of storage without memory limitations.In this thesis, we argue for a decentralized systems paradigm and, in conjunction with IoT and the blockchain. Our contributions are as follows. First, we introduce the term networks and service architectures and how it is possible to use blockchain in the real world. We consider different architectures in IoT systems and show the blockchain en-counter with the IoT and the resulting behavior. Second, we detect most of the frequent types of attacks in IoT related to using blockchain in the systems. We also describe how the blockchain works and illustrate a variety of security problems in systems. Fur-thermore, we discuss how the blockchain solves security problems by comparing different blockchains and explain how users handle their communication without third-party de-pendence. As our third contribution, we propose a novel architecture that consists of finding global identification in distributed applications and enable decentralized systems to be more secure with the help of blockchain technology. We also validate the proposed architecture and novel decentralized application development to evaluate high efficiency by combining blockchain, DHT, and biometric technologies.
33
Myers, Andrew C. (Andrew Clifford). "Mostly-static decentralized information flow control". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/16717.
Abstract (sommario):
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 169-174) and index.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The growing use of mobile code in downloaded programs such as applets and servlets has increased interest in robust mechanisms for ensuring privacy and secrecy. Common security mechanisms such as sand boxing and access control are either too restrictive or too weak -- they prevent applications from sharing data usefully, or allow private information to leak. For example, security mechanisms in Java prevent many useful applications while still permitting Trojan horse applets to leak private information. This thesis describes the decentralized label model, a new model of information flow control that protects private data while allowing applications to share data. Unlike previous approaches to privacy protection based on information flow, this label model is decentralized: it allows cooperative computation by mutually distrusting principals, without mediation by highly trusted agents. Cooperative computation is possible because individual principals can declassify their own data without infringing on other principals' privacy. The decentralized label model permits programs using it to be checked statically, which is important for the precise detection of information leaks. This thesis also presents the new language J flow, an extension to the Java programming language that incorporates the decentralized label model and permits static checking of information flows within programs. Variable declarations in J flow programs are annotated with labels that allow the static checker to check programs for information leaks efficiently, in a manner similar to type checking. Often, these labels can be inferred automatically, so annotating programs is not onerous. Dynamic checks also may be used safely when static checks are insufficiently powerful. A compiler has been implemented for the J flow language. Because most checking is performed statically at compile time, the compiler generates code with few additional dynamic tests, improving performance.
by Andrew C. Myers.
Ph.D.
34
Wong, Henry (Henry Yung Han) 1978. "Decentralized control of multiple collaborating agents". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8602.
Abstract (sommario):
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 131-133) and index.
This thesis investigates the effect of various factors on multi-agent collaboration in a simulated fire-fighting domain. A simulator was written that models fires and fire-fighting agents in an area of a few square city blocks. Different scenarios were constructed to test the effects of limiting the agents' knowledge and to compare the effects of coordinating the agents through a single entity with the results obtained through independent decision making. This research demonstrates that the amount of information available to each agent and the agents' ability to act on this information are typically much more important factors than the use of a complex planning mechanism; as long as the agents are aware of each other and take minimal steps to coordinate their actions they are able to achieve results that are nearly as good as those achieved by much more complicated algorithms.
by Henry Wong.
M.Eng.and S.B.
35
Schultz, David Andrew. "Decentralized information flow control for databases". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78363.
Abstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 177-194).
Privacy and integrity concerns have been mounting in recent years as sensitive data such as medical records, social network records, and corporate and government secrets are increasingly being stored in online systems. The rate of high-profile breaches has illustrated that current techniques are inadequate for protecting sensitive information. Many of these breaches involve databases that handle information for a multitude of individuals, but databases don't provide practical tools to protect those individuals from each other, so that task is relegated to the application. This dissertation describes a system that improves security in a principled way by extending the database system and the application platform to support information flow control. Information flow control has been gaining traction as a practical way to protect information in the contexts of programming languages and operating systems. Recent research advocates the decentralized model for information flow control (DIFC), since it provides the necessary expressiveness to protect data for many individuals with varied security concerns.However, despite the fact that most applications implicated in breaches rely on relational databases, there have been no prior comprehensive attempts to extend DIFC to a database system. This dissertation introduces IFDB, which is a database management system that supports DIFC with minimal overhead. IFDB pioneers the Query by Label model, which provides applications with a simple way to delineate constraints on the confidentiality and integrity of the data they obtain from the database. This dissertation also defines new abstractions for managing information flows in a database and proposes new ways to address covert channels. Finally, the IFDB implementation and case studies with real applications demonstrate that database support for DIFC improves security, is easy for developers to use, and has good performance.
by David Andrew Schultz.
Ph.D.
36
Allen, Steven D. M. Eng Massachusetts Institute of Technology. "DRACL (Decentralized resource access control list)". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/112855.
Abstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 132-135).
DRACL is a privacy-preserving, scalable, secure, and developer and user friendly federated access control system. It allows producers to manage, through a single authentication provider, which consumers can access what content across all content hosts that support the DRACL protocol. It preserves user privacy by not revealing the producers' social networks to content hosts and consumers and allowing content consumers to access content anonymously. Unlike existing solutions, DRACL is federated (cf. Facebook Connect, Google Sign-In), does not have a single point of failure (cf. Mozilla Persona, OpenID), and does not reveal its producers' social networks to content hosts (cf. Facebook Connect's user_friends permission).
by Steven D. Allen.
M. Eng.
37
Attaran, Rezaei Behnam. "Distributed and decentralized complex networks design, simulation, analysis, and applications /". Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1414125511&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
38
Gudkov, Aleksei. "Control over organization. Control in centralized and decentralized systems". Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/666837.
Abstract (sommario):
Este proyecto de investigación interdisciplinario tiene como objetivo el análisis del concepto moderno y los factores determinantes del control de la persona; revisa el desarrollo histórico del concepto; discutir la capacidad de identificar el poder de control; ayuda a descubrir la distribución fáctica del poder y las jerarquías; propone métodos de control y análisis de controlar la estructura de la red. En la investigación, el control de las empresas y los indicadores clave de control se discuten desde el punto de vista legal, económico, contractual y tecnológico.
El derecho corporativo moderno y las reglas de gobierno corporativo tienen una brecha entre las reglas legales obsoletas y las nuevas estructuras de red; legislación y procesos sociales. Hay muchas situaciones no estándar en las que la ley moderna no funciona: las estructuras VIE en China con control indirecto; Activistas minoritarios cooperativos; y, finalmente, organizaciones virtuales descentralizadas. Los métodos de determinación de control solo funcionan en los casos simples. Con respecto al control por coaliciones o existente en organizaciones de redes, las definiciones de control son vagas y no tienen una metodología clara. Sin embargo, las herramientas económicas y sociales como el Análisis Cooperativo de Juegos y el Análisis de Redes Sociales pueden arrojar luz sobre el proceso de formación de coaliciones y crear nuevas regulaciones.
Centrándose en la mejor práctica de la regulación de accionistas accionistas, protección de derechos de accionistas minoritarios, conflictos entre accionistas minoritarios y controladores y la implementación de efectividad de la ley el proyecto refuerza la regulación existente y facilita el desarrollo de nuevas reglas para mejorar la efectividad del análisis de control sobre el poder excesivo de la persona controladora teniendo en cuenta los aspectos prácticos de la implementación de la ley. La investigación muestra que el control sobre la organización puede ser completo, parcial, lateral, vertical, pero no puede ser absoluto.
El objetivo complementario de la investigación es un análisis de los determinantes modernos de la distribución de control sobre corporaciones, activos, transacciones y organizaciones descentralizadas en la red distribuida de blockchain.
Sobre la base del análisis, se proponen los métodos de determinación del control en coaliciones complicadas y organizaciones de redes. El control en la red descentralizada se logró e implementó más rápido con poca cantidad de errores, por lo tanto, el control es más completo y generalizado. La presente investigación sugiere formas de superar los problemas existentes con una identificación más precisa del control en coaliciones, sociedades de redes y organizaciones con una estructura de propiedad borrosa.
Se discuten los aspectos factibles del control exclusivo, compartido y móvil. El control se considera esencia móvil, que podría existir por separado de los beneficiarios y las partes interesadas de la organización controladora y controlada. La investigación subraya la importancia y la influencia de las coaliciones y las sociedades de redes. El análisis de control de red permite el análisis de la distribución de control entre coaliciones.This interdisciplinary research project aims analysis of modern concept and determinants of controlling person; reviews historical development of concept; discuss the ability to identify power of control; helps to uncover factual distribution of power and hierarchies; proposes methods of control and analysis of controlling network structure. In the research the control over companies and key indicators of control are discussed from the legal, economical, contractual, and technological point of view. Modern corporate law and corporate governance rules have a gap between obsolete legal rules and new network structures; legislation and social processes. There are a lot of non-standard situations where modern law is not working: VIE structures in China with indirect control; Cooperative minority Activists; and, finally, Decentralized Virtual Organizations. Methods of control determination are working only in the simple cases. In respect to control by coalitions or existing in networking organizations, the definitions of control are vague and have no clear methodology. Though, the economic and social tools like Cooperative Game Analysis and Social Network Analysis can shed light on the process of formation of coalitions and create new regulations. Focusing on the best practice of the controlling shareholder regulation, minority shareholders rights protection, conflicts between minority and controlling shareholder and effectiveness of law implementation the project strengths the existing regulation and facilitates development of new rules to enhance the effectiveness of analysis of control over excessive power of the controlling person taking into account practical aspects of law implementation. The research shows that the control over organization can be full, partial, lateral, vertical but cannot be absolute. The complimentary objective of the research is an analysis of modern determinants of control distribution over corporation, assets, transactions, and decentralized organizations on blockchain distributed network. On the ground of analysis, the methods of determination of control in complicated coalitions and network organizations are proposed. The control in decentralized network achieved and implemented faster with low quantity of errors, therefore, control is more comprehensive and pervasive. The present research suggests ways to overcome the existing problems with more precise identification of control in coalitions, networking societies and organizations with blurred ownership structure. The feasible aspects of sole, shared and movable control are discussed. Control is viewed as movable essence, which could exist separately from beneficiaries and stakeholders of controlling and controlled organization. The research underlines the importance and influence of coalitions and networking societies. The Network Control Analysis enables analysis of control distribution among coalitions.
39
Bundell, G. A. "Robust decentralized adaptive control in the manipulator control problem". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355669.
40
Schmidt, Henning. "Model based design of decentralized control configurations". Licentiate thesis, KTH, Signals, Sensors and Systems, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1438.
41
Aghdam, Amir G. "Decentralized control of systems using switching methods". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/NQ53722.pdf.
42
Dejak, Steven Ivan. "Decentralized PI control of web handling machines". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/MQ53430.pdf.
43
Levedahl, Blaine Alexander. "Decentralized Autonomous Control of Aerospace Vehicle Formations". NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-03062003-104749/.
Abstract (sommario):
Two approaches for the autonomous control of aerospace vehicle formations are developed. The development of the approaches relies on fundamental work in the areas of distributed control; specifically modal, robust, optimal, and decentralized control. The algorithms are shown to satisfy five separation principles that simplify design and enable the algorithms to be implemented reliably. The autonomous controllers uniformly dampen the modes of the formation (global control) using a decentralized approach and a nearest-neighbor approach. A numerical example illustrates robust formation changes from 9-vehicle (3 x 3) grids to V-type formations.
44
Osman, Johari Halim Shah. "Decentralized and hierarchical control of robot manipulators". Thesis, City University London, 1991. http://openaccess.city.ac.uk/7758/.
Abstract (sommario):
This thesis deals with the decentralized and hierarchical control of a class of robot manipulators, where the robot manipulator is treated as a large scale uncertain system. The work is divided into three parts. The first part is concerned with the development of an integrated mathematical model of the robot manipulator. The model of the system considered comprises the mechanical part of the robot manipulator, the actuators, as well as the gear trains. The formulation results in nonlinear time varying state equations, which represent a more realistic model of the robotic system. A procedure to decompose and reduce the integrated model of the robot manipulator into a set of interconnected subsystems with bounded uncertainties description is then presented. In the second part of the research, two decentralized control approaches based on a deterministic approach are outlined. The first method uses only the local states as the feedback information. It is shown that the robot manipulator utilizing the proposed controller is practically stable and tracks a reference trajectory if a given sufficient condition is satisfied. In the second approach, the controller is designed based on the local states as well as the states of the neighbouring subsystems as the feedback information. It is shown that the controller will force the nonlinear uncertain robot manipulator to track a desired trajectory to within a small uniform ultimate boundedness set. In the final part of the study, two hierarchical control concepts for robot manipulator are proposed. The controllers are formulated based on a deterministic approach. It is shown that the hierarchical control strategies are capable of withstanding the expected variations and uncertainties and will render the robot manipulator to track a prescribed trajectory satisfactorily. In synthesizing the proposed controllers, it is assumed that the upper bounds on the nonlinearities, couplings and uncertainties present in the system are available. The proposed methods are simple and robust to parameter variations and uncertainties present in the system. The performance of the proposed control algorithms are evaluated by means of computer simulations. The proposed control laws are applied to a three degree of freedom revolute robot manipulator actuated by DC motors. Several case studies have been considered, and the simulation results are presented and discussed. In this thesis, the term practical stability means bounded stability in the sense of Lyapunov.
45
Shah, Parikshit (Parikshit Mayank). "A partial order approach to decentralized control". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66462.
Abstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 173-177).
In this thesis we consider the problem of decentralized control of linear systems. We employ the theory of partially ordered sets (posets) to model and analyze a class of decentralized control problems. Posets have attractive combinatorial and algebraic properties; the combinatorial structure enables us to model a rich class of communication structures in systems, and the algebraic structure allows us to reparametrize optimal control problems to convex problems. Building on this approach, we develop a state-space solution to the problem of designing H₂-optimal controllers. Our solution is based on the exploitation of a key separability property of the problem that enables an efficient computation of the optimal controller by solving a small number of uncoupled standard Riccati equations. Our approach gives important insight into the structure of optimal controllers, such as controller degree bounds that depend on the structure of the poset. A novel element in our state-space characterization of the controller is a pair of transfer functions, that belong to the incidence algebra of the poset, are inverses of each other, and are intimately related to estimation of the state along the different paths in the poset. We then view the control design problem from an architectural viewpoint. We propose a natural architecture for poset-causal controllers. In the process, we establish interesting connections between concepts from order theory such as Mobius inversion and control-theoretic concepts such as state estimation, innovation, and separability principles. Finally, we prove that the H₂-optimal controller in fact posseses the proposed controller structure, thereby proving the optimality of the architecture.
by Parikshit Shah.
Ph.D.
46
Cliffer, Natan Tsvi Cohen. "Decentralized information flow control on a cluster". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/45985.
Abstract (sommario):
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 53-54).
Information flow control security models can prevent programs from divulging sensitive information in unexpected ways. There has been significant work on tracking information flow between processes in the same computer at the operating system level. I present a modification to the Flume information flow control system for OpenBSD that allows information flow to be tracked between programs on different computers, as long as the system software on all involved computers is maintained by the same trusted entity. This allows the benefits of Flume to be applied to computer systems that take the cluster approach to scaling.
by Natan Tsvi Cohen Cliffer.
M.Eng.
47
Singh, Abhinav Kumar. "Decentralized estimation and control for power systems". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24467.
Abstract (sommario):
This thesis presents a decentralized alternative to the centralized state-estimation and control technologies used in current power systems. Power systems span over vast geographical areas, and therefore require a robust and reliable communication network for centralized estimation and control. The supervisory control and data acquisition (SCADA) systems provide such a communication architecture and are currently employed for centralized estimation and control of power systems in a static manner. The SCADA systems operate at update rates which are not fast enough to provide appropriate estimation or control of transient or dynamic events occurring in power systems. Packet-switching based networked control system (NCS) is a faster alternative to SCADA systems, but it suffers from some other problems such as packet dropouts, random time delays and packet disordering. A stability analysis framework for NCS in power systems has been presented in the thesis considering these problems. Some other practical limitations and problems associated with real-time centralized estimation and control are computational bottlenecks, cyber threats and issues in acquiring system-wide parameters and measurements. The aforementioned problems can be solved by a decentralized methodology which only requires local parameters and measurements for estimation and control of a local unit in the system. The cumulative effect of control at all the units should be such that the global oscillations and instabilities in the power system are controlled. Such a decentralized methodology has been presented in the thesis. The method for decentralization is based on a new concept of `pseudo-inputs' in which some of measurements are treated as inputs. Unscented Kalman filtering (UKF) is applied on the decentralized system for dynamic state estimation (DSE). An extended linear quadratic regulator (ELQR) has been proposed for the optimal control of each local unit such that the whole power system is stabilized and all the oscillations are adequately damped. ELQR requires DSE as a prerequisite. The applicability of integrated system for dynamic estimation and control has been demonstrated on a model 16-machine 68-bus benchmark system.
48
Reichard, Karl Martin. "Decentralized control of large space structures:an overview". Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43282.
Abstract (sommario):
This thesis examines several techniques for the design of decentralized control strategies for the active control of vibrational damping in large space structures. A brief description of the finite element method is presented to explain the derivation of mathematical models of flexible structures represented by systems of linear second-order ordinary differential equations. The fundamental ideas of modal analysis are introduced to explain the concepts of vibrational modes and mode shapes, and derive the modal coordinate state space representation of flexible structures.
The decentralized fixed modes of a system are defined, and several important characterizations of decentralized fixed modes are presented. Alternate characterizations of fixed modes yield additional insight into the nature: of fixed modes and often provide new methods for calculating the fixed modes of a system.
The use of collocated rate feedback for robust vibrational damping control is described. It is shown that the robustness of collocated rate feedback is due to the positivity of large space structures, an extension of the mathematical concept of positive real functions to dynamic systems.
Another strategy for the control of vibrational damping in large space structures, known as uniform damping control, is also described. It is shown that compared to collocated rate feedback, uniform damping control achieves increased performance at the price of decreased robustness at low frequencies.
The application of decomposition techniques to the design of decentralized control laws is described, and a special type of decomposition known as an overlapping decomposition is introduced. It is shown how overlapping decompositions can be used to design control laws for systems for which the more familiar disjoint decomposition techniques often fail to yield satisfactory results.
Finally, these decentralized control techniques are illustrated using a model of a proposed large space structure, the NASA CO FS mast.Master of Science
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Grosdidier, Pierre Morari Manfred. "Interaction measures for systems under decentralized control /". Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03192008-093230.
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Malek, Babak. "Some observations toward decentralized control under saturation". Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Fall2009/b_malek_120409.pdf.
Abstract (sommario):
Thesis (M.S. in electrical engineering)--Washington State University, December 2009.Title from PDF title page (viewed on Feb. 4, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 52-53).