Thèses sur le sujet « Network fault model »

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1

Ozkok, Ozlem. « A realistic model of network survivability ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FOzkok.pdf.

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Thesis (M.S. in Information Technology Management and M.S. in Computer Science)--Naval Postgraduate School, September 2003.
Thesis advisor(s): Geoffrey Xie, Alex Bordetsky. Includes bibliographical references (p. 47-48). Also available online.
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Cabezas, Rodríguez Juan Pablo. « Generative adversarial network based model for multi-domain fault diagnosis ». Tesis, Universidad de Chile, 2019. http://repositorio.uchile.cl/handle/2250/170996.

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Memoria para optar al título de Ingeniero Civil Mecánico
Con el uso de las redes neuronal profundas ganando terreno en el área de PHM, los sensores disminuyendo progresivamente su precio y mejores algoritmos, la falta de datos se ha vuelto un problema principal para los modelos enfocados en datos. Los datos etiquetados y aplicables a escenarios específicos son, en el mejor de los casos, escasos. El objetivo de este trabajo es desarrollar un método para diagnosticas el estado de un rodamiento en situaciones con datos limitados. Hoy en día la mayoría de las técnicas se enfocan en mejorar la precisión del diagnóstico y en estimar la vida útil remanente en componentes bien documentados. En el presente, los métodos actuales son ineficiente en escenarios con datos limitados. Se desarrolló un método en el cual las señales vibratorias son usadas para crear escalogramas y espectrogramas, los cuales a su vez se usan para entrenar redes neuronales generativas y de clasificación, en función de diagnosticar un set de datos parcial o totalmente desconocido, en base a uno conocido. Los resultados se comparan con un método más sencillo en el cual la red para clasificación es entrenada con el set de datos conocidos y usada directamente para diagnosticar el set de datos desconocido. El Case Western Reserve University Bearing Dataset y el Machine Failure Prevention Technology Bearing Dataset fueron usados como datos de entrada. Ambos sets se usaron como conocidos tanto como desconocidos. Para la clasificación una red neuronal convolucional (CNN por sus siglas en inglés) fue diseñada. Una red adversaria generativa (GAN por sus siglas en inglés) fue usada como red generativa. Esta red fue basada en una introducida en el paper StarGAN: Unified Generative Adversarial Networks for Multi-Domain Image-to-Image Translation. Los resultados fueron favorables para la red CNN mientras que fueron -en general- desfavorables para la red GAN. El análisis de resultados sugiere que la función de costo es inapropiada para el problema propuesto. Las conclusiones dictaminan que la traducción imagen-a-imagen basada en la función ciclo no funciona correctamente en señal vibratorias para diagnóstico de rodamientos. With the use of deep neural networks gaining notoriety on the prognostics & health management field, sensors getting progressively cheaper and improved algorithms, the lack of data has become a major issue for data-driven models. Data which is labelled and applicable for specific scenarios is scarce at best. The purpose of this works is to develop a method to diagnose the health state of a bearing on limited data situations. Now a days most techniques focus on improving accuracy for diagnosis and estimating remaining useful life on well documented components. As it stands, current methods are ineffective on limited data scenarios. A method was developed were in vibration signals are used to create scalograms and spectrograms, which in turn are used to train generative and classification neural networks with the goal of diagnosing a partially or totally unknown dataset based on a fully labelled one. Results were compared to a simpler method in which a classification network is trained on the labelled dataset to diagnose the unknown dataset. As inputs the Case Western Reserve University Bearing Dataset (CWR) and the Society for Machine Failure Prevention Technology Bearing Dataset. Both datasets are used as labelled and unknown. For classification a Convolutional Neural Network (CNN) is designed. A Generative Adversarial Network (GAN) is used as generative model. The generative model is based of a previous paper called StarGAN: Unified Generative Adversarial Networks for Multi-Domain Image-to-Image Translation. Results were favourable for the CNN network whilst generally negative for the GAN network. Result analysis suggests that the cost function is unsuitable for the proposed problem. Conclusions state that cycle based image-to-image translation does not work correctly on vibration signals for bearing diagnosis.
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Fani, Mehran. « Fault diagnosis of an automotive suspension system ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016.

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With the development of the embedded application and driving assistance systems, it becomes relevant to develop parallel mechanisms in order to check and to diagnose these new systems. In this thesis we focus our research on one of this type of parallel mechanisms and analytical redundancy for fault diagnosis of an automotive suspension system. We have considered a quarter model car passive suspension model and used a parameter estimation, ARX model, method to detect the fault happening in the damper and spring of system. Moreover, afterward we have deployed a neural network classifier to isolate the faults and identifies where the fault is happening. Then in this regard, the safety measurements and redundancies can take into the effect to prevent failure in the system. It is shown that The ARX estimator could quickly detect the fault online using the vertical acceleration and displacement sensor data which are common sensors in nowadays vehicles. Hence, the clear divergence is the ARX response make it easy to deploy a threshold to give alarm to the intelligent system of vehicle and the neural classifier can quickly show the place of fault occurrence.
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Aull, Mark J. « Comparison of Fault Detection Strategies on a Low Bypass Turbofan Engine Model ». University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321368833.

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Almulla, Muhannad. « Implementation of an Arc Model for MV Network with Resonance Earthing ». Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278499.

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The most common fault type in electric power systems is the line to groundfault. In this type of faults, an electrical arc is usually developed. The thesispresents a mathematical model that describes the behavior of the arc during afault. The arc model has been verified based on real and simulated tests thatwere conducted on a system that has resonant earthing coil.In addition, two studies have been conducted on the same verified system.The first studied was implemented to see the effect of detuning the resonantearthing coil at different levels. It was noted that detuning the coil affected ACand the DC components in the arc faults. Also, the detuning affected the arcextinction.The second study has been looking at the effects of implementing a parallelresistor to the resonant earthing coil. The tests have been conducted usingdifferent set values of the resistor. In some of the studied cases and during thetesting period, the resistor has affected the self-extinguish behavior of the arc.
Den vanligaste feltypen i elektriska kraftsystem är fas till jord. I denna typ avfel utvecklas vanligtvis en elektrisk ljusbåge. Examensarbetet presenterar enmatematisk modell som beskriver ljusbågens beteende under ett fel. Bågmodellenhar verifierats baserat på verkliga tester och simuleringar som utfördespå ett system som har resonansjordningsspole.Dessutom har två studier genomförts på samma verifierade system. Denförsta studien genomfördes för att se effekten av avstämning av den resonantajordningspolen på olika nivåer. Det noterades att avstämning av spolen påverkadeACoch DC-komponenterna i ljusbågsfel.Avstämningen påverkade ocksåljusbågens släckning.Den andra studien har tittat på effekterna av att implementera ett parallelltmotstånd till den resonanta jordningsspolen. Testen har utförts med olikainställda värden på motståndet. I några av de studerade fallen och under testperiodenhar motståndet påverkat ljusbågens självsläckande beteende.
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Chen, Yun. « Mining Dynamic Recurrences in Nonlinear and Nonstationary Systems for Feature Extraction, Process Monitoring and Fault Diagnosis ». Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6072.

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Real-time sensing brings the proliferation of big data that contains rich information of complex systems. It is well known that real-world systems show high levels of nonlinear and nonstationary behaviors in the presence of extraneous noise. This brings significant challenges for human experts to visually inspect the integrity and performance of complex systems from the collected data. My research goal is to develop innovative methodologies for modeling and optimizing complex systems, and create enabling technologies for real-world applications. Specifically, my research focuses on Mining Dynamic Recurrences in Nonlinear and Nonstationary Systems for Feature Extraction, Process Monitoring and Fault Diagnosis. This research will enable and assist in (i) sensor-driven modeling, monitoring and optimization of complex systems; (ii) integrating product design with system design of nonlinear dynamic processes; and (iii) creating better prediction/diagnostic tools for real-world complex processes. My research accomplishments include the following. (1) Feature Extraction and Analysis: I proposed a novel multiscale recurrence analysis to not only delineate recurrence dynamics in complex systems, but also resolve the computational issues for the large-scale datasets. It was utilized to identify heart failure subjects from the 24-hour heart rate variability (HRV) time series and control the quality of mobile-phone-based electrocardiogram (ECG) signals. (2) Modeling and Prediction: I proposed the design of stochastic sensor network to allow a subset of sensors at varying locations within the network to transmit dynamic information intermittently, and a new approach of sparse particle filtering to model spatiotemporal dynamics of big data in the stochastic sensor network. It may be noted that the proposed algorithm is very general and can be potentially applicable for stochastic sensor networks in a variety of disciplines, e.g., environmental sensor network and battlefield surveillance network. (3) Monitoring and Control: Process monitoring of dynamic transitions in complex systems is more concerned with aperiodic recurrences and heterogeneous types of recurrence variations. However, traditional recurrence analysis treats all recurrence states homogeneously, thereby failing to delineate heterogeneous recurrence patterns. I developed a new approach of heterogeneous recurrence analysis for complex systems informatics, process monitoring and anomaly detection. (4) Simulation and Optimization: Another research focuses on fractal-based simulation to study spatiotemporal dynamics on fractal surfaces of high-dimensional complex systems, and further optimize spatiotemporal patterns. This proposed algorithm is applied to study the reaction-diffusion modeling on fractal surfaces and real-world 3D heart surfaces.
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Chauvin, Benjamin. « Applicability of the mechanics-based restoration : boundary conditions, fault network and comparison with a geometrical method ». Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0160/document.

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La restauration structurale a pour objectifs de déterminer la géométrie passée des roches et de valider les interprétations structurales. Les méthodes classiques sont basées sur des hypothèses géométriques et/ou cinématiques, et imposent un style de déformation. Les méthodes géomécaniques, en intégrant le comportement élastique des roches et les lois fondamentales de conservation mécanique, visent à résoudre les problèmes des méthodes classiques. Toutefois, il y a des incertitudes sur le choix des paramètres élastiques, et les contraintes de maillage rendent difficile l’utilisation de cette méthode comme un outil de validation des interprétations structurales. Le choix d’une méthode de restauration en particulier est rendu difficile par le fait qu’il y ait plusieurs approches de restauration géomécanique, en plus des nombreuses méthodes géométriques et cinématiques. Cette thèse présente en premier lieu une revue des différentes méthodes géomécaniques 3D visant à déplisser et annuler l’action des failles dans un modèle géologique. L’objectif de cette revue est de présenter les forces ainsi que les limites, théoriques et pratiques, de chaque méthode. Dans un second temps, à travers la restauration d’un modèle analogique (sandbox), nous présentons nos travaux sur le choix de conditions aux limites appropriées pour obtenir un modèle restauré cohérent. Ce modèle structural expérimental a été déformé en laboratoire et présente plusieurs analogies avec des structures extensives postérieures à une base salifère. Grâce à l’observation de l’évolution temporelle de la géométrie du modèle analogique sur une coupe, nous montrons qu’une condition aux limites correspondant à un raccourcissement latéral est nécessaire. Ce raccourcissement peut être estimé par la méthode de la surface transférée. De plus, nous définissons de nouvelles conditions aux limites de contacts de failles pour restaurer correctement le réseau de failles complexe du modèle analogique. Ces nouvelles conditions lient les bords internes des surfaces de failles et connectent les composantes connexes des failles coupées et déplacées par des failles plus récentes. Troisièmement, le test de différents paramètres élastiques indique que le module de Young, défini homogène au sein d’un modèle géologique, n’a quasiment pas d’effet sur le champ de déplacement. Toutefois, le coefficient de Poisson a un impact significatif sur la dilatation volumique. Dans un dernier temps, nous comparons la restauration géomécanique avec une méthode géométrique qui repose sur un modèle chronostratigraphique (GeoChron) qui fait une bijection de chaque point du sous-sol avec son équivalent dans l’espace de dépôt (Wheeler). Nous montrons que les deux approches de restauration fournissent des modèles restaurés du modèle analogique qui sont similaires géométriquement. La méthode géométrique a de nombreux avantages pour obtenir rapidement et avec précision le modèle restauré, mais elle manque de flexibilité sur le choix des contraintes de la déformation. La force de la méthode géomécanique est de pouvoir définir des conditions aux limites personnalisées et des comportements mécaniques spécifiques pour gérer les contextes mécaniquement complexes
Structural restoration aims to recover rock paleo-geometries and to validate structural interpretations. The classical methods are based on geometric/kinematic assumptions and impose a style of deformation. Geomechanical methods, by integrating rock elastic behavior and fundamental mechanical conservation laws, aim to solve issues of classical methods. However several studies show that the geomechanical restoration lacks physical consistency in particular because of the boundary conditions. There are uncertainties on the choice of the elastic properties, and the meshing constraints limit this method to be used as a validation tool of structural interpretations. The choice of a specific restoration method is difficult because there are many geomechanical restoration approaches, in addition to the numerous geometric/kinematic methods. Firstly, this thesis presents a review of the various 3D geomechanical methods to unfold and unfault a 3D geological model. The objective is to present their, theoretical and practical, strengths and limits. Secondly, through the restoration of a structural sandbox model, we worked on the choice of adequate boundary conditions to get a proper restored model. This structural sandbox model was deformed in laboratory and presents several analogies with supra-salt extensional structures. Thanks to the observation of the analog model geometry through time on a cross section, we show that a lateral shortening boundary condition is necessary. We show that this shortening can be estimated by the area-depth method. Moreover we define new fault contact conditions to handle complex fault networks. These novel conditions tie internal fault borders and join parts of offset faults. Thirdly, the test of several elastic parameters shows that Young’s modulus, homogeneous within a geological model, has almost no effect on the restoration displacement field. However, Poisson’s ratio has a significant impact on the volume dilatation. Finally, we compare the mechanics-based restoration method with a geometric-based method relying on a chronostratigraphic model (GeoChron) mapping any point of the subsurface to its image in depositional (Wheeler) space. We show that both methods provide a geometrically similar restored state for the analog model. The geometric method has numerous advantages to quickly and accurately get a restored model, but it lacks flexibility on the choice of the deformation constraints. The geomechanical restoration method force is to define custom boundary conditions and specific mechanical behaviors to handle complex contexts
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Lanciotti, Noemi. « Amélioration de la robustesse des machines synchrones spéciales multi phases dans un contexte de transport urbain ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLN055/document.

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Les machines à commutation de flux cinq-phases présentent une tolérance aux pannes et une robustesse qui les rendent très intéressantes dans un point de vue de la fiabilité, comme montré dans le premier chapitre.Dans ces travaux de thèse nous avons explorés la possibilité de détecter les défauts qui affectent cette machine par la signature des vibrations générées dans la machine.En utilisant les outils physiques et mathématiques présentés dans le deuxième chapitre, nous avons construit deux modèles multiphysiques, un modèle aux les éléments finis développé dans le troisième chapitre et un modèle analytique, appelé aux réseaux de perméances, dans le quatrième chapitre.Le comportement vibratoire de la machine a été étudié à l'aide de ces deux modèles, en régimesain et en défaut afin de connaitre comment ce comportement est influencé par les grandeurs électriques et magnétiques de la machine.Par ailleurs nous avons étudié la possibilité de détecter et discriminer les différents types de défauts.Le modèle analytique se présente comme un bon estimateur du comportement en défaut de la machine, malgré ses écarts avec la simulation.Dans le cinquième chapitre, les deux modèles multiphysiques ont été validés par des essais expérimentaux et nous avons pu expliquer le comportement en défaut d’un point de vue mécanique plutôt que magnétique.Enfin, dans le sixième chapitre, nous avons utilisé les deux modèles pour étudier le comportement en défaut de la machine, à des vitesses au-dessus de la limite expérimentale (3100 tr/min)
Five-phase flux switching machines have a fault tolerance and robustness that makes them very interesting from the point of view of reliability, as shown in chapter one of this work. In our studies we have explored the possibility of detecting faults that affect this type of machine using the signature of stator vibrations.Using the physical and mathematical tools presented in chapter two, we improved two multyphisics models, one based on finite elements method that it's presented in chapter three and the seconde one analitycal model, called permeance networks, in chapter four. The vibratory behavior of the machine was studied using these two models, under healthy and faulty conditions, in order to know how this behavior is influenced by the electrical and magnetic magnitudes of the machine. In addition, we have studied the possibility of detecting and discriminating different types of faults. Analytical model is a good estimator of fault behavior of the machine, despite its differences with the simulation.In chapter five, the two multiphysical models have been validated by experimental tests and we have been able to explain fault behavior by mechanical origin rather than magnetic origin.Finally, in chapter six, we used both models to study the fault behavior of the machine, at speeds above the experimental limit (3100 rpm)
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Pospíšil, Zdeněk. « Indikace zemních spojení na venkovních vedeních ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-264926.

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This master´s thesis deals with the indication and localization of earth faults in overhead lines. Earth fault is the most frequently occurring type of fault in medium voltage overhead lines – it covers approx. 95% of all faults and is very difficult to indicate and localize them correctly and in time with currently available methods on the market. Therefore is very important to study earth fault and its indication, localization. The thesis consists of a theoretical and a practical part. The theoretical part deals with faults in overhead networks with different type of neutral grounding, mainly with one phase to the ground fault in the compensated, ungrounded, solidly grounded and via resistance grounded networks. Most of the theoretical part is dedicated to one phase to the ground fault in the compensated and ungrounded networks, where this type fault is called the earth fault. In the compensated and ungrounded networks is described in details behavior – voltage and current relations during both steady state and transient state earth fault. The theoretical part is further dedicated to detection methods of earth faults and their preconditions for use. There is described also in details the complete procedure of earth fault detection, which includes indication, unhealthy feeder determination and exact position or line section localization. End of the theoretical part is then focused on determination of accuracy requirements for measurement of basic quantities and computation of other parameters. The practical part deals with a work at medium distribution network model, which includes familiarization with the model, detailed verification of its functionality and behavior during the earth fault, obtaining faults records and algorithmization of methods: method of qu – diagram and method of first half - period, which are able to detect unhealthy feeder. This part of the thesis was put together based on a demand of company Mega, corp., which wanted to verify function of both above mentioned and by them not yet tested methods.
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Chua, Eng Hong. « Determine network survivability using heuristic models ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FChua%5FEngHong.pdf.

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Arad, Cosmin Ionel. « Programming Model and Protocols for Reconfigurable Distributed Systems ». Doctoral thesis, KTH, Programvaruteknik och Datorsystem, SCS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122311.

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Distributed systems are everywhere. From large datacenters to mobile devices, an ever richer assortment of applications and services relies on distributed systems, infrastructure, and protocols. Despite their ubiquity, testing and debugging distributed systems remains notoriously hard. Moreover, aside from inherent design challenges posed by partial failure, concurrency, or asynchrony, there remain significant challenges in the implementation of distributed systems. These programming challenges stem from the increasing complexity of the concurrent activities and reactive behaviors in a distributed system on the one hand, and the need to effectively leverage the parallelism offered by modern multi-core hardware, on the other hand. This thesis contributes Kompics, a programming model designed to alleviate some of these challenges. Kompics is a component model and programming framework for building distributed systems by composing message-passing concurrent components. Systems built with Kompics leverage multi-core machines out of the box, and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic execution replay for debugging, testing, and reproducible behavior evaluation for largescale Kompics distributed systems. The same system code is used for both simulation and production deployment, greatly simplifying the system development, testing, and debugging cycle. We highlight the architectural patterns and abstractions facilitated by Kompics through a case study of a non-trivial distributed key-value storage system. CATS is a scalable, fault-tolerant, elastic, and self-managing key-value store which trades off service availability for guarantees of atomic data consistency and tolerance to network partitions. We present the composition architecture for the numerous protocols employed by the CATS system, as well as our methodology for testing the correctness of key CATS algorithms using the Kompics simulation framework. Results from a comprehensive performance evaluation attest that CATS achieves its claimed properties and delivers a level of performance competitive with similar systems which provide only weaker consistency guarantees. More importantly, this testifies that Kompics admits efficient system implementations. Its use as a teaching framework as well as its use for rapid prototyping, development, and evaluation of a myriad of scalable distributed systems, both within and outside our research group, confirm the practicality of Kompics.

QC 20130520

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Arad, Cosmin. « Programming Model and Protocols for Reconfigurable Distributed Systems ». Doctoral thesis, SICS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-24202.

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Distributed systems are everywhere. From large datacenters to mobile devices, an ever richer assortment of applications and services relies on distributed systems, infrastructure, and protocols. Despite their ubiquity, testing and debugging distributed systems remains notoriously hard. Moreover, aside from inherent design challenges posed by partial failure, concurrency, or asynchrony, there remain significant challenges in the implementation of distributed systems. These programming challenges stem from the increasing complexity of the concurrent activities and reactive behaviors in a distributed system on the one hand, and the need to effectively leverage the parallelism offered by modern multi-core hardware, on the other hand. This thesis contributes Kompics, a programming model designed to alleviate some of these challenges. Kompics is a component model and programming framework for building distributed systems by composing message-passing concurrent components. Systems built with Kompics leverage multi-core machines out of the box, and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic execution replay for debugging, testing, and reproducible behavior evaluation for large-scale Kompics distributed systems. The same system code is used for both simulation and production deployment, greatly simplifying the system development, testing, and debugging cycle. We highlight the architectural patterns and abstractions facilitated by Kompics through a case study of a non-trivial distributed key-value storage system. CATS is a scalable, fault-tolerant, elastic, and self-managing key-value store which trades off service availability for guarantees of atomic data consistency and tolerance to network partitions. We present the composition architecture for the numerous protocols employed by the CATS system, as well as our methodology for testing the correctness of key CATS algorithms using the Kompics simulation framework. Results from a comprehensive performance evaluation attest that CATS achieves its claimed properties and delivers a level of performance competitive with similar systems which provide only weaker consistency guarantees. More importantly, this testifies that Kompics admits efficient system implementations. Its use as a teaching framework as well as its use for rapid prototyping, development, and evaluation of a myriad of scalable distributed systems, both within and outside our research group, confirm the practicality of Kompics.
Kompics
CATS
REST
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Goparaju, Manoj Kumar. « Parametric fault model for linear threshold logic networks / ». Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1079666531&sid=27&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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Cherrared, Sihem. « Gestion des fautes dans les réseaux multi-tenants et programmables ». Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S016.

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La virtualisation est une tentative prometteuse pour résoudre certains défis de la 5G. La virtualisation consiste à exécuter des fonctions réseaux en tant que logiciels sur une infrastructure physique partagée. Cela optimise les coûts de déploiement et simplifie la gestion, mais il introduit de nouveaux défis tels que la topologie de réseau dynamique et le manque de visibilité. Dans cette thèse, nous proposons un algorithme d’auto-modélisation et un processus de diagnostic actif pour relever ces défis. Nous apprenons et validons le modèle défini par injection de pannes. Nous appliquons notre approche au use-case "virtual Ip Multimedia (vIMS)"
Network Functions Virtualization (NFV) is one promising attempt at solving some of the 5G challenges. NFV is about running network functions as virtualized workloads on commodity hardware. This may optimize deployment costs and simplify the life cycle management, but it introduces new challenges such as the dynamic network topology and the lack of visibility. In this thesis, we propose a self-modeling algorithm and an active diagnosis process to face these challenges. We define a dependency model learned from faults injection. The self-modeling and the active diagnosis approach was applied to the real-world virtual Ip Multimedia Subsystem (vIMS) use-case
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Yang, Jianchang. « FAULT-TOLERANT DISTRIBUTED CHANNEL ALLOCATION ALGORITHMS FOR CELLULAR NETWORKS ». UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/329.

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In cellular networks, channels should be allocated efficiently to support communication betweenmobile hosts. In addition, in cellular networks, base stations may fail. Therefore, designing a faulttolerantchannel allocation algorithm is important. That is, the algorithm should tolerate failuresof base stations. Many existing algorithms are neither fault-tolerant nor efficient in allocatingchannels.We propose channel allocation algorithms which are both fault-tolerant and efficient. In theproposed algorithms, to borrow a channel, a base station (or a cell) does not need to get channelusage information from all its interference neighbors. This makes the algorithms fault-tolerant,i.e., the algorithms can tolerate base station failures, and perform well in the presence of thesefailures.Channel pre-allocation has effect on the performance of a channel allocation algorithm. Thiseffect has not been studied quantitatively. We propose an adaptive channel allocation algorithmto study this effect. The algorithm allows a subset of channels to be pre-allocated to cells. Performanceevaluation indicates that a channel allocation algorithm benefits from pre-allocating allchannels to cells.Channel selection strategy also inuences the performance of a channel allocation algorithm.Given a set of channels to borrow, how a cell chooses a channel to borrow is called the channelselection problem. When choosing a channel to borrow, many algorithms proposed in the literaturedo not take into account the interference caused by borrowing the channel to the cells which havethe channel allocated to them. However, such interference should be considered; reducing suchinterference helps increase the reuse of the same channel, and hence improving channel utilization.We propose a channel selection algorithm taking such interference into account.Most channel allocation algorithms proposed in the literature are for traditional cellular networkswith static base stations and the neighborhood relationship among the base stations is fixed.Such algorithms are not applicable for cellular networks with mobile base stations. We proposea channel allocation algorithm for cellular networks with mobile base stations. The proposedalgorithm is both fault-tolerant and reuses channels efficiently.KEYWORDS: distributed channel allocation, resource planning, fault-tolerance, cellular networks,3-cell cluster model.
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Ocampo-Martínez, Carlos. « Model Predictive Control of Complex Systems including Fault Tolerance Capabilities : Application to Sewer Networks ». Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6196.

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El control en temps real de xarxes de clavegueram (RTC) desenvolupa un paper fonamental dins de la gestió dels recursos hídrics relacionats amb el cicle urbà de l'aigua i, en general, amb el seu cicle natural. Un adequat disseny de control per a xarxes de clavegueram evita impactes mediambientals negatius originats per inundacions i/o alta pol·lució producte de condicions meteorològiques xtremes. No obstant, s'ha de tenir en compte que aquestes xarxes, a més de la seva grandària i quantitat de variables i instrumentació, són sistemes rics en dinàmiques complexes i altament no lineals. Aquest fet, unit a les condicions atmosfèriques extremes, fan necessari utilitzar una estratègia de control capaç¸ de suportar totes aquestes condicions. En aquest sentit, dins del camp del (RTC) de xarxes de clavegueram es destaquen les estratègies de control predictiu basat en model (MPC), les quals són alternatives adequades per al control de configuracions multivariable i de gran escala, aplicades com estratègies de control global del sistema. A m´es, permeten optimitzar la resposta del sistema tenint en compte diversos índexs de rendiment (control multiobjectiu).
Aquesta tesi s'enfoca en el disseny de controladors MPC per a xarxes de clavegueram considerant diverses metodologies de modelat. Addicionalment, analitza les situacions en les quals es presenten fallades als actuadors de la xarxa, proposant estratègies per a mantenir la resposta del sistema amb la menor degradació possible dels objectius de control, malgrat la presència de la fallada. En la primera part s'introdueixen els conceptes principals dels temes a tractar en la tesi: xarxes de clavegueram, MPC i tolerància a fallades. Seguidament, es presenta la tècnica de modelat utilitzada per a definir el model d'una xarxa de clavegueram. Finalment, es presenta i descriu el cas d'aplicació en la tesi: la xarxa de clavegueram de Barcelona (Espanya).
La segona part es centra en dissenyar controladors MPC per al cas d'estudi. S'han considerat dos tipus de model de xarxa: (i) un model lineal, el qual aproxima els comportaments no lineals de la xarxa, donant origen a estratègies MPC lineals amb les seves conegudes avantatges de l'optimització convexa i escalabilitat; i (ii) un model híbrid, el qual inclou les dinàmiques de commutació més representatives d'una xarxa de clavegueram com són els sobreeixidors.
En aquest últim cas es proposa una nova etodologia de modelat híbrid per a xarxes de clavegueram i es dissenyen estratègies de control predictives basades en aquests models (HMPC), les quals calculen lleis de control globalment òptimes. Addicionalment, es proposa una estratègia de relaxació del problema d'optimització discreta per a evitar els grans temps de còmput requerits per a calcular la llei de control HMPC.
Finalment, la tercera part de la tesi s'encarrega d'estudiar les capacitats de tolerància a fallades en actuadors de llaços de control MPC. En el cas de xarxes de clavegueram, la tesi considera fallades en les comportes de derivació i de retenció d'aigües residuals. A més, es proposa un modelat híbrid per a fallades que faci que el problema d'optimització associat no perdi la seva convexitat. Així, es proposen dos estratègies de HMPC tolerant a fallades (FTMPC): l'estratègia activa, la qual utilitza les avantatges d'una arquitectura de control tolerant a fallades (FTC), i l'estratègia passiva, la qual només depèn de la robustesa intrínseca de les tècniques de control MPC. Com a extensió a l'estudi de tolerància a fallades, es proposa una avaluació d'admissibilitat per a configuracions d'actuadors en fallada agafant com a referència la degradació dels objectius de control. El m-etode, basat en satisfacció de restriccions, permet avaluar l'admissibilitat d'una configuració d'actuadors en fallada i, en cas de no ser admesa, evitaria el procés de resoldre un problema d'optimització amb un alt cost computacional.
Paraules clau: control predictiu basat en model, sistemes de clavegueram, sistemes híbrids, MLD, control tolerant a fallades, satisfacció de restriccions.
El control en tiempo real de redes de alcantarillado (RTC) desempeña un papel fundamental dentro de la gestión de los recursos hídricos relacionados con el ciclo urbano del agua y, en general, con su ciclo natural. Un adecuado diseño de control para de redes de alcantarillado evita impactos medioambientales negativos originados por inundaciones y/o alta polución producto de condiciones meteorológicas extremas. Sin embargo, se debe tener en cuenta que estas redes, además de su gran tamaño y cantidad de variables e instrumentación, son sistemas ricos en dinámicas complejas y altamente no lineales. Este hecho, unido a unas condiciones atmosféricas extremas, hace necesario utilizar una estrategia de control capaz de soportar todas estas condiciones. En este sentido, dentro del campo del RTC de redes de alcantarillado se destacan las estrategias de control predictivo basadas en modelo (MPC), las cuales son alternativas adecuadas para el control de configuraciones multivariable y de gran escala, aplicadas como estrategias de control global del sistema. Además, permiten optimizar el desempeño del sistema teniendo en cuenta diversos índices de rendimiento (control multiobjetivo).
Esta tesis se enfoca en el diseño de controladores MPC para redes de alcantarillado considerando diversas metodologías de modelado. Adicionalmente, analiza las situaciones en las cuales se presentan fallos en los actuadores de la red, proponiendo estrategias para mantener el desempeño del sistema y evitando la degradación de los objetivos de control a pesar de la presencia del fallo. En la primera parte se introducen los conceptos principales de los temas a tratar en la tesis: redes de alcantarillado, MPC y tolerancia a fallos. Además, se presenta la técnica de modelado utilizada para definir el modelo de una red de alcantarillado. Finalmente, se presenta y describe el caso de aplicación considerado en la tesis: la red de alcantarillado de Barcelona (España).
La segunda parte se centra en diseñar controladores MPC para el caso de estudio. Dos tipos de modelo de la red son considerados: (i) un modelo lineal, el cual aproxima los comportamientos no lineales de la red, dando origen a estrategias MPC lineales con sus conocidas ventajas de optimización convexa y escalabilidad; y (ii) un modelo híbrido, el cual incluye las dinámicas de conmutación más representativas de una red de alcantarillado como lo son los rebosaderos. En este último caso se propone una nueva metodología de modelado híbrido para redes de alcantarillado y se diseñan estrategias de control predictivas basadas en estos modelos (HMPC), las cuales calculan leyes de control globalmente óptimas. Adicionalmente se propone una estrategia de relajación del problema de optimización discreto para evitar los grandes tiempos de cálculo que pudieran ser requeridos al obtener la ley de control HMPC.
Finalmente, la tercera parte de la tesis se ocupa de estudiar las capacidades de tolerancia a fallos en actuadores de lazos de control MPC. En el caso de redes de alcantarillado, la tesis considera fallos en las compuertas de derivación y de retención de aguas residuales. De igual manera, se propone un modelado híbrido para los fallos que haga que el problema de optimización asociado no pierda su convexidad. Así, se proponen dos estrategias de HMPC tolerante a fallos (FTMPC): la estrategia activa, la cual utiliza las ventajas de una arquitectura de control tolerante a fallos (FTC), y la estrategia pasiva, la cual sólo depende de la robustez intrínseca de las técnicas de control MPC. Como extensión al estudio de tolerancia a fallos, se propone una evaluación de admisibilidad para configuraciones de actuadores en fallo tomando como referencia la degradación de los objetivos de control. El método, basado en satisfacción de restricciones, permite evaluar la admisibilidad de una configuración de actuadores en fallo y, en caso de no ser admitida, evitaría el proceso de resolver un problema de optimización con un alto coste computacional.
Palabras clave: control predictivo basado en modelo, sistemas de alcantarillado, sistemas híbridos, MLD, control tolerante a fallos, satisfacción de restricciones.
Real time control (RTC) of sewer networks plays a fundamental role in the management of hydrological systems, both in the urban water cycle, as well as in the natural water cycle. An adequate design of control systems for sewer networks can prevent the negative impact on the environment that Combined Sewer Overflow (CSO) as well as preventing flooding within city limits when extreme weather conditions occur. However, sewer networks are large scale systems with many variables, complex dynamics and strong nonlinear behaviour. Any control strategy applied should be capable of handling these challenging requirements. Within the field of RTC of sewer networks for global network control, the Model Predictive Control (MPC) strategy stands out due to its ability to handle large scale, nonlinear and multivariable systems. Furthermore, this strategy allows performance optimization, taking into account several control objectives simultaneously.
This thesis is devoted to the design of MPC controllers for sewer networks, as well as the complementary modelling methodologies. Furthermore, scenarios where actuator faults occur are specially considered and strategies to maintain performance or at least minimizing its degradation in presence of faults are proposed. In the first part of this thesis, the basic concepts are introduced: sewer networks, MPC and fault tolerant control. In addition, the modelling methodologies used to describe such systems are presented. Finally the case study of this thesis is described: the sewer network of the city of Barcelona (Spain). The second part of this thesis is centered on the design of MPC controllers for the proposed case study. Two types of models are considered: (i) a linear model whose corresponding MPC strategy is known for its advantages such as convexity of the optimization problem and existing pro of sofstability, and (ii) a hybrid model which allows the inclusion of state dependent hybrid dynamics such as weirs. In the latter case, a new hybrid modelling methodology is introduced and hybrid model predictive control (HMPC) strategies based on these models are designed. Furthermore, strategies to relax the optimization problem are introduced to reduce calculation time required for the HMPC control law.
Finally, the third part of this thesis is devoted to study the fault tolerance capabilities of MPC controllers. Actuator faults in retention and redirection gates are considered. Additionally, hybrid modelling techniques are presented for faults which, in the linear case, can not be treated without loosing convexity of the related optimization problem. Two fault tolerant HMPC strategies are compared: the active strategy, which uses the information from a diagnosis system to maintain control performance, and the passive strategy which only relies on the intrinsic robustness of the MPC control law. As an extension to the study of fault tolerance, the admissibility of faulty actuator configurations is analyzed with regard to the degradation of control objectives. The method, which is based on constraint satisfaction, allows the admissibility evaluation of actuator fault configurations, which avoids the process of solving the optimization problem with its related high computational cost.
Keywords: MPC, sewer networks, hybrid systems, MLD, fault tolerant control, constraints satisfaction.
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Ayad, Fady. « How is AI research applied in the field of network fault management ». Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-20124.

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The internet growth rapidly increased by the years, and the traffic is increasing daily. The management of the network is becoming more and more complexed for humans to handle on their own, with that being said a new direction of using Artificial Intelligence (AI) technologies is being implemented in the direction of network fault management. In order to keep up with the development network, new solutions need to be implemented. Traditional network fault management are dependent of system administrators and there is too much human error that can happen during operations. That’s why AI is a great tool to be used in future network fault management. There are currently many challenges within network fault management, and this makes an opportunity for AI to be implemented. The studies shows that AI subpart “supervised learning” is the most popular used in network fault management. AI have shown that there is potential to tackle problems such as detection, prediction and also improve the system as whole.
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Wang, Xiaofeng. « Simulation models for rolling bearing vibration generation and fault detection via neural networks ». Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362159.

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Odeh, Abdel-Rahman M. M. « Fault tolerant ATM LAN/LAN internetworking for connectionless data services and their performance evaluation ». Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284077.

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Norman, Gustaf. « Sensor Validation Using Linear Parametric Models, Artificial Neural Networks and CUSUM ». Thesis, Linköpings universitet, Reglerteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119004.

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Siemens gas turbines are monitored and controlled by a large number of sensors and actuators. Process information is stored in a database and used for offline calculations and analyses. Before storing the sensor readings, a compression algorithm checks the signal and skips the values that explain no significant change. Compression of 90 % is not unusual. Since data from the database is used for analyses and decisions are made upon results from these analyses it is important to have a system for validating the data in the database. Decisions made on false information can result in large economic losses. When this project was initiated no sensor validation system was available. In this thesis the uncertainties in measurement chains are revealed. Methods for fault detection are investigated and finally the most promising methods are put to the test. Linear relationships between redundant sensors are derived and the residuals form an influence structure allowing the faulty sensor to be isolated. Where redundant sensors are not available, a gas turbine model is utilized to state the input-output relationships so that estimates of the sensor outputs can be formed. Linear parametric models and an ANN (Artificial Neural Network) are developed to produce the estimates. Two techniques for the linear parametric models are evaluated; prediction and simulation. The residuals are also evaluated in two ways; direct evaluation against a threshold and evaluation with the CUSUM (CUmulative SUM) algorithm. The results show that sensor validation using compressed data is feasible. Faults as small as 1% of the measuring range can be detected in many cases.
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Kleman, Björn, et Henrik Lindgren. « Evaluation of model-based fault diagnosis combining physical insights and neural networks applied to an exhaust gas treatment system case study ». Thesis, Linköpings universitet, Fordonssystem, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-176650.

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Fault diagnosis can be used to early detect faults in a technical system, which means that workshop service can be planned before a component is fully degraded. Fault diagnosis helps with avoiding downtime, accidents and can be used to reduce emissions for certain applications. Traditionally, however, diagnosis systems have been designed using ad hoc methods and a lot of system knowledge. Model-based diagnosis is a systematic way of designing diagnosis systems that is modular and offers high performance. A model-based diagnosis system can be designed by making use of mathematical models that are otherwise used for simulation and control applications. A downside of model-based diagnosis is the modeling effort needed when no accurate models are available, which can take a large amount of time. This has motivated the use of data-driven diagnosis. Data-driven methods do not require as much system knowledge and modeling effort though they require large amounts of data and data from faults that can be hard to gather. Hybrid fault diagnosis methods combining models and training data can take advantage of both approaches decreasing the amount of time needed for modeling and does not require data from faults. In this thesis work a combined data-driven and model-based fault diagnosis system has been developed and evaluated for the exhaust treatment system in a heavy-duty diesel engine truck. The diagnosis system combines physical insights and neural networks to detect and isolate faults for the exhaust treatment system. This diagnosis system is compared with another system developed during this thesis using only model-based methods. Experiments have been done by using data from a heavy-duty truck from Scania. The results show the effectiveness of both methods in an industrial setting. It is shown how model-based approaches can be used to improve diagnostic performance. The hybrid method is showed to be an efficient way of developing a diagnosis system. Some downsides are highlighted such as the performance of the system developed using data-driven and model-based methods depending on the quality of the training data. Future work regarding the modularity and transferability of the hybrid method can be done for further evaluation.
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Raju, Madhanmohan. « Group based fault-tolerant physical intrusion detection system using fuzzy based distributed RSSI processing ». University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1393237072.

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Segovia, Castillo Pablo. « Model-based control and diagnosis of inland navigation networks ». Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/671004.

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This thesis regards the problem of optimal management of water resources in inland navigation networks from a control theory perspective. In particular, the main objective to be attained consists in guaranteeing the navigability condition of the network, i.e., ensuring that the water levels are such that vessels can travel safely. More specifically, the water levels must be kept within an interval around the setpoint. Other common objectives include minimizing the operational cost and ensuring a long lifespan of the equipment. However, inland navigation networks are large-scale systems characterized by a number of features that complicate their management, namely complex dynamics, large time delays and negligible bottom slopes. In order to achieve the optimal management, the efficient control of the hydraulic structures, e.g., gates, weirs and locks, must be ensured. To this end, a control-oriented modeling approach is derived based on an existing simplified model obtained from the Saint-Venant equations. This representation reduces the complexity of the original model, provides flexibility and allows to coordinate current and delayed information in a systematic manner. However, the resulting model formulation belongs to the class of delayed descriptor systems, for which standard control and state estimation tools would need to be extended. Instead, model predictive control and moving horizon estimation can be easily adapted for this formulation, as well as being able to deal with physical and operational constraints in a natural manner. Due to the large dimensionality of inland navigation networks, a centralized implementation is often neither possible nor desirable. In this regard, non-centralized approaches are considered, decomposing the overall system in subsystems and distributing the computational burden among the local agents, each of them in charge of meeting the local objectives. Given the fact that inland navigation networks are strongly coupled systems, a distributed approach is followed, featuring a communication protocol among local agents. Despite the optimality of the computed solutions, state estimation will only be effective provided that the sensors acquire reliable data. Likewise, the control actions will only be applied correctly if the actuators are not impacted by faults. Indeed, any error can lead to an inefficient management of the system. Therefore, the last part of the thesis is concerned with the design of supervisory strategies that allow to detect and isolate faults in inland navigation networks. All the presented modeling, centralized and distributed control and state estimation and fault diagnosis approaches are applied to a realistic case study based on the inland navigation network in the north of France to validate their effectiveness.
Cette thèse contribue à répondre au problème de la gestion optimale des ressources en eau dans les réseaux de navigation intérieure du point de vue de la théorie du contrôle. Les objectifs principales à atteindre consistent à garantir la navigabilité des réseaux de voies navigables, veiller à la réduction des coûts opérationnels et à la longue durée de vie des équipements. Lors de la conception de lois de contrôle, les caractéristiques des réseaux doivent être prises en compte, à savoir leurs dynamiques complexes, des retards variables et l’absence de pente. Afin de réaliser la gestion optimale, le contrôle efficace des structures hydrauliques doit être assuré. A cette fin, une approche de modélisation orientée contrôle est dérivée. Cependant, la formulation obtenue appartient à la classe des systèmes de descripteurs retardés, pour lesquels la commande prédictive MPC et l’estimation d’état sur horizon glissant MHE peuvent être facilement adaptés à cette formulation, tout en permettant de gérer les contraintes physiques et opérationnelles de manière naturelle. En raison de leur grande dimensionnalité, une mise en œuvre centralisée n’est souvent ni possible ni souhaitable. Compte tenu du fait que les réseaux de navigation intérieure sont des systèmes fortement couplés, une approche distribuée est proposée, incluant un protocole de communication entre agents. Malgré l’optimalité des solutions, toute erreur peut entraîner une gestion inefficace du système. Par conséquent, les dernières contributions de la thèse concernent la conception de stratégies de supervision permettant de détecter et d’isoler les pannes des équipements. Toutes les approches présentées sont appliquées à une étude de cas réaliste basée sur le réseau de voies navigables du nord e la France afin de valider leur efficacité.
La present tesi versa sobre el problema de la gestió òptima dels recursos hídrics en vies de navegació interior des de la perspectiva de la teoria de control. Concretament, l’objectiu principal radica en garantir la condició de navegabilitat del s is tema. Dit d’una altra manera, es vol garantir que els nivells d’aigua siguin tals que les embarcacions puguin navegar-hi de forma segura. Aquest objectiu s’assoleix mantenint els nivells a l’interior d’un interval construït al voltant del punt d’operació. Altres objectius comuns en aquest context as piren a minimitzar els cos tos associats a l’operació dels equips, així com a prolongar-ne la seva vida útil. Ara bé, les vies de navegació interior són sistemes a gran escala caracteritzats per dinàmiques complexes, grans retards temporals i pendents negligibles, aspectes que en dificulten la gestió. Per tal d’assolir la ges tió òptima, s’ha de garantir un control eficient de les estructures hidràuliques tals com comportes, dics i rescloses. Amb aquesta finalitat, es deriva un modelat del sistema orientat a control basat en un model existent simplificat, obtingut a partir de les equacions de Saint-Venant. Aquesta nova representació redueix la complexitat del model original, proporciona flexibilitat i permet coordinar informació actual i retardada de manera sistemàtica. Malgrat això, la formulació resultant pertany a la classe de sistemes descriptors amb retard, per als quals les tècniques de control i d’estimació estàndards necessiten ser esteses. En canvi, el control predictiu basat en models i l’estimació d’estat amb horitzó lliscant es poden adaptar fàcilment a la formulació proposada. A més, són capaços de tractar amb restriccions físiques i operacionals de forma natural. Degut a les grans dimensions de les vies de navegació interior, una implementació centralitzada no resulta, tot sovint, ni possible ni desitjada. Per tal de pal·liar aquest problema, es consideren mètodes no centralitzats. D’aquesta manera, es descompon el sistema global en subsistemes i es distribueix la càrrega computacional del problema centralitzat entre els agents locals, de manera que cadascun d’ells s’encarrega de fer complir els objectius locals . En tant que les vies de navegació interior són sistemes fortament connectats, se segueix un plantejament distribuït, incloent un protocol de comunicació entre els agents locals. Malgrat la optimalitat dels resultats que les estratègies proposades puguin proporcionar, l’estimació d’estat només serà efectiva a condició que els sensors proveeixin informació fiable. Igualment, les accions de control únicament es podran aplicar correctament si els actuadors no estan afectats per fallades. En efecte, qualsevol error pot conduir a una gestió ineficaç del sistema. És per aquest motiu que la darrera part de la tes i tracta s obre el disseny d’estratègies de supervisió, que permetin detectar i aïllar fallades en vies de navegació interior. Tots els resultats de modelat, control i estimació d’es tat centralitzats i distribuïts, així com de diagnòstic de fallades, s’apliquen a un cas d’estudi realista, basat en les vies de navegació interior del nord de França, per tal de provar-ne la seva eficàcia.
La presente tesis versa sobre el problema de la gestión óptima de los recursos hídricos en vías de navegación interior desde la perspectiva de la teoría de control. En concreto, el objetivo principal consiste en garantizar la condición de navegabilidad del sistema, es decir, garantizar que los niveles de agua de los canales sean tales que las embarcaciones puedan navegar de forma segura. Dicho objetivo se consigue manteniendo los niveles dentro de un intervalo alrededor del punto de operación. Otros objetivos comunes consisten en minimizar los costes asociados a la operación de los equipos, así como a extender su vida útil. Hay que tener en cuenta que las vías de navegación interiores son sistemas a gran escala caracterizados por dinámicas complejas, grandes retardos temporales y pendientes prácticamente nulas, lo que dificulta su gestión. Para alcanzar la gestión óptima, se debe garantizar un control eficiente de las estructuras hidráulicas tales como compuertas, diques y esclusas, y para ello se deriva un modelado del sistema orientado a control, basado en un modelo simplificado ya existente, obtenido a partir de las ecuaciones de Saint-Venant. Esta nueva representación reduce la complejidad del modelo original, proporciona flexibilidad y permite coordinar información actual y retardada de forma sistemática. Sin embargo, la formulación resultante pertenece a la clase de sistemas descriptores con retardos, para los cuales las técnicas de control y de estimación de estado estándares necesitan ser extendidas. En cambio, el control predictivo basado en modelos y la estimación de estado con horizonte deslizante pueden ser fácilmente adaptadas para la formulación propuesta, además de permitir lidiar con restricciones físicas y operacionales de forma natural. Hay que tener en cuenta que, debido a las grandes dimensiones de las vías de navegación interior, una implementación centralizada no es, a menudo, ni posible ni deseada, y para paliar este problema se consideran los enfoques no centralizados. De este modo, se descompone el sistema global en subsistemas y se distribuye la carga computacional del problema centralizado entre los agentes locales, de manera que cada uno de ellos se encarga de cumplir los objetivos locales. Como las vías de navegación interior son sistemas fuertemente conectados, se sigue un enfoque distribuido, incluyendo un protocolo de comunicación entre los agentes. También se ha de considerar que la estimación de estado sólo será efectiva a condición de que los sensores provean información fiable. Asimismo, las acciones de control únicamente se podrán aplicar correctamente si los actuadores no están afectados por fallas. En efecto, cualquier avería puede conducir a una gestión ineficaz del sistema. Es por ello que la última parte de la tesis trata sobre el diseño de estrategias de supervisión que permitan detectar y aislar fallas en vías de navegación interior. Todos los resultados de modelado, control y estimación de estado centralizados y distribuidos, así como de diagnóstico de fallas, se aplican a un caso de estudio realista basado en las vías de navegación interior del norte de Francia para probar su eficacia.
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Kmelnitsky, Vitaly M. « Automated On-line Diagnosis and Control Configuration in Robotic Systems Using Model Based Analytical Redundancy ». Digital WPI, 2002. https://digitalcommons.wpi.edu/etd-theses/167.

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Because of the increasingly demanding tasks that robotic systems are asked to perform, there is a need to make them more reliable, intelligent, versatile and self-sufficient. Furthermore, throughout the robotic system?s operation, changes in its internal and external environments arise, which can distort trajectory tracking, slow down its performance, decrease its capabilities, and even bring it to a total halt. Changes in robotic systems are inevitable. They have diverse characteristics, magnitudes and origins, from the all-familiar viscous friction to Coulomb/Sticktion friction, and from structural vibrations to air/underwater environmental change. This thesis presents an on-line environmental Change, Detection, Isolation and Accommodation (CDIA) scheme that provides a robotic system the capabilities to achieve demanding requirements and manage the ever-emerging changes. The CDIA scheme is structured around a priori known dynamic models of the robotic system and the changes (faults). In this approach, the system monitors its internal and external environments, detects any changes, identifies and learns them, and makes necessary corrections into its behavior in order to minimize or counteract their effects. A comprehensive study is presented that deals with every stage, aspect, and variation of the CDIA process. One of the novelties of the proposed approach is that the profile of the change may be either time or state-dependent. The contribution of the CDIA scheme is twofold as it provides robustness with respect to unmodeled dynamics and with respect to torque-dependent, state-dependent, structural and external environment changes. The effectiveness of the proposed approach is verified by the development of the CDIA scheme for a SCARA robot. Results of this extensive numerical study are included to verify the applicability of the proposed scheme.
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Morais, Anderson Nunes Paiva. « Injeção de ataques baseado em modelo para teste de protocolos de segurança ». [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/275915.

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Orientadores: Eliane Martins, Ricardo de Oliveira Anido
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: Neste trabalho apresentamos uma proposta de geração de ataques para testes de protocolos de segurança. O objetivo é detectar vulnerabilidades de um protocolo, que um atacante pode explorar para causar falhas de segurança. Nossa proposta usa um injetor de falhas para emular um atacante que possui total controle do sistema de comunicação. Como o sucesso dos testes depende principalmente dos ataques injetados, nós propomos uma abordagem baseada em modelos para a geração de ataques. O modelo representa ataques conhecidos e reportados do protocolo sob teste. A partir deste modelo, cenários de ataque são gerados. Os cenários estão em um formato que é independente do injetor de falhas usado. Usando refinamentos e transformações, pode-se converter a descrição do cenário de ataque em scripts específicos do injetor de falhas. A proposta pode ser completamente apoiada por ferramentas de software. Nós ilustramos o uso da proposta com um estudo de caso, um protocolo de segurança para dispositivos móveis
Abstract: We present an attack injection approach for security protocols testing. The goal is to uncover protocol vulnerabilities that an attacker can exploit to cause security failures. Our approach uses a fault injector to emulate an attacker that has control over the communication system. Since the success of the tests depends greatly on the attacks injected, we propose a model-based approach for attack generation. The model represents reported known attacks to the protocol under test. From this model, attack scenarios are generated. The scenarios are in a format that is independent of the fault injector used. Using refinements and transformations, the abstract scenario specification can be converted to the specific fault injector scripts. The approach can be completely supported by tools. We illustrate the use of the approach in a case study, a security protocol for mobile devices
Universidade Estadual de Campi
Tolerancia a Falhas
Mestre em Ciência da Computação
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König, Johan. « Analyzing Substation Automation System Reliability using Probabilistic Relational Models and Enterprise Architecture ». Doctoral thesis, KTH, Industriella informations- och styrsystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145006.

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Modern society is unquestionably heavily reliant on supply of electricity. Hence, the power system is one of the important infrastructures for future growth. However, the power system of today was designed for a stable radial flow of electricity from large power plants to the customers and not for the type of changes it is presently being exposed to, like large scale integration of electric vehicles, wind power plants, residential photovoltaic systems etc. One aspect of power system control particular exposed to these changes is the design of power system control and protection functionality. Problems occur when the flow of electricity changes from a unidirectional radial flow to a bidirectional. Such an implication requires redesign of control and protection functionality as well as introduction of new information and communication technology (ICT). To make matters worse, the closer the interaction between the power system and the ICT systems the more complex the matter becomes from a reliability perspective. This problem is inherently cyber-physical, including everything from system software to power cables and transformers, rather than the traditional reliability concern of only focusing on power system components. The contribution of this thesis is a framework for reliability analysis, utilizing system modeling concepts that supports the industrial engineering issues that follow with the imple-mentation of modern substation automation systems. The framework is based on a Bayesian probabilistic analysis engine represented by Probabilistic Relational Models (PRMs) in com-bination with an Enterprise Architecture (EA) modeling formalism. The gradual development of the framework is demonstrated through a number of application scenarios based on substation automation system configurations. This thesis is a composite thesis consisting of seven papers. Paper 1 presents the framework combining EA, PRMs and Fault Tree Analysis (FTA). Paper 2 adds primary substation equipment as part of the framework. Paper 3 presents a mapping between modeling entities from the EA framework ArchiMate and substation automation system configuration objects from the IEC 61850 standard. Paper 4 introduces object definitions and relations in coherence with EA modeling formalism suitable for the purpose of the analysis framework. Paper 5 describes an extension of the analysis framework by adding logical operators to the probabilistic analysis engine. Paper 6 presents enhanced failure rates for software components by studying failure logs and an application of the framework to a utility substation automation system. Finally, Paper 7 describes the ability to utilize domain standards for coherent modeling of functions and their interrelations and an application of the framework utilizing software-tool support.

QC 20140505

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Wang, Ye. « Advances in state estimation, diagnosis and control of complex systems ». Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/669680.

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This dissertation intends to provide theoretical and practical contributions on estimation, diagnosis and control of complex systems, especially in the mathematical form of descriptor systems. The research is motivated by real applications, such as water networks and power systems, which require a control system to provide a proper management able to take into account their specific features and operating limits in presence of uncertainties related to their operation and failures from component malfunctions. Such a control system is expected to provide an optimal operation to obtain efficient and reliable performance. State estimation is an essential tool, which can be used not only for fault diagnosis but also for the controller design. To achieve a satisfactory robust performance, set theory is chosen to build a general framework for descriptor systems subject to uncertainties. Under certain assumptions, these uncertainties are propagated and bounded by deterministic sets that can be explicitly characterized at each iteration step. Moreover, set-invariance characterizations for descriptor systems are also of interest to describe the steady performance, which can also be used for active mode detection. For the controller design for complex systems, new developments of economic model predictive control (EMPC) are studied taking into account the case of underlying periodic behaviors. The EMPC controller is designed to be recursively feasible even with sudden changes in the economic cost function and the closed-loop convergence is guaranteed. Besides, a robust technique is plugged into the EMPC controller design to maintain these closed-loop properties in presence of uncertainties. Engineering applications modeled as descriptor systems are presented to illustrate these control strategies. From the real applications, some additional difficulties are solved, such as using a two-layer control strategy to avoid binary variables in real-time optimizations and using nonlinear constraint relaxation to deal with nonlinear algebraic equations in the descriptor model. Furthermore, the fault-tolerant capability is also included in the controller design for descriptor systems by means of the designed virtual actuator and virtual sensor together with an observer-based delayed controller.
Esta tesis propone contribuciones de carácter teórico y aplicado para la estimación del estado, el diagnóstico y el control óptimo de sistemas dinámicos complejos en particular, para los sistemas descriptores, incluyendo la capacidad de tolerancia a fallos. La motivación de la tesis proviene de aplicaciones reales, como redes de agua y sistemas de energía, cuya naturaleza crítica requiere necesariamente un sistema de control para una gestión capaz de tener en cuenta sus características específicas y límites operativos en presencia de incertidumbres relacionadas con su funcionamiento, así como fallos de funcionamiento de los componentes. El objetivo es conseguir controladores que mejoren tanto la eficiencia como la fiabilidad de dichos sistemas. La estimación del estado es una herramienta esencial que puede usarse no solo para el diagnóstico de fallos sino también para el diseño del control. Con este fin, se ha decidido utilizar metodologías intervalares, o basadas en conjuntos, para construir un marco general para los sistemas de descriptores sujetos a incertidumbres desconocidas pero acotadas. Estas incertidumbres se propagan y delimitan mediante conjuntos que se pueden caracterizar explícitamente en cada instante. Por otra parte, también se proponen caracterizaciones basadas en conjuntos invariantes para sistemas de descriptores que permiten describir comportamientos estacionarios y resultan útiles para la detección de modos activos. Se estudian también nuevos desarrollos del control predictivo económico basado en modelos (EMPC) para tener en cuenta posibles comportamientos periódicos en la variación de parámetros o en las perturbaciones que afectan a estos sistemas. Además, se demuestra que el control EMPC propuesto garantiza la factibilidad recursiva, incluso frente a cambios repentinos en la función de coste económico y se garantiza la convergencia en lazo cerrado. Por otra parte, se utilizan técnicas de control robusto pata garantizar que las estrategias de control predictivo económico mantengan las prestaciones en lazo cerrado, incluso en presencia de incertidumbre. Los desarrollos de la tesis se ilustran con casos de estudio realistas. Para algunas de aplicaciones reales, se resuelven dificultades adicionales, como el uso de una estrategia de control de dos niveles para evitar incluir variables binarias en la optimización y el uso de la relajación de restricciones no lineales para tratar las ecuaciones algebraicas no lineales en el modelo descriptor en las redes de agua. Finalmente, se incluye también una contribución al diseño de estrategias de control con tolerancia a fallos para sistemas descriptores.
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Malik, Naveed ur Rehman. « Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator ». Doctoral thesis, KTH, Elektrisk energiomvandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174349.

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This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G). A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine. To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode. As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents. Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented. Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments.

QC 20151006

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Giuntini, Felipe Taliar. « Um modelo de rede de sensores sem fio auto-organizada e tolerante a falhas para detecção de incêndios ». Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8296.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
The wildfires caused by human occupation is one of the factors that most contributes to deforestation of conservation areas, resulting in a number of issues for ecological systems. Premature fire detection lead to the elimination or minimize the damage that will be caused by a fire incident. Wireless Sensor Networks (WSNs) has been shown to be a good alternative for environmental monitoring applications, as they can collect and send the information in real-time, such as humidity, wind and temperature of various parts of the forest. Due to problems such as power limitation, communication failure and loss of nodes, the network topology is constantly changing, requiring mechanisms to achieve self-organization and fault tolerance. This paper proposes the development of a model and application in selforganizing and fault-tolerant WSNs for fire detection in conservation areas. To achieve self-organization and fault tolerance is encouraged local interactions between neighboring nodes that monitor the same region and the coordination of tasks, through a supervisor node, equipped with a framework for developing fault-tolerant applications based on components. Using a component redundancy technique with adaptive approach, the fire detection solution was implemented. Each component, ie, different implementations of the same specification, it is loaded and unloaded from runtime memory while the node assumes the role of coordinator. The results are stored and after execution of all components is achieved a consensus. For analysis and validation of the model and the application was simulated to 60 events in the sensor network in a real scenario, using the Sinalgo simulator. The results were classified as True (partial or absolute) or False (partial or absolute). In 45% of consensus identified a possible fault in the application and in only 35% there was absolute consensus.
Os incêndios causados pela ocupação humana é um dos fatores que mais contribui para o desmatamento das áreas de preservação ambiental, acarretando uma série de problemas aos sistemas ecológicos. A detecção precoce do fogo visa eliminar ou minimizar o dano que será causado por um incidente de fogo. Redes de Sensores sem Fio (RSSFs) tem se mostrado uma boa alternativa para aplicacões de monitoramento ambiental, visto que podem coletar e enviar informações em tempo real, como umidade, vento e temperatura de vários pontos da floresta. Devido a problemas como limitação de energia, falha na comunicacão e perda de n´os sensores, a topologia da rede muda constantemente, exigindo mecanismos que permitem alcançar a auto-organização e a tolerância a falhas. Este trabalho propõe o desenvolvimento de um modelo e uma aplicação em RSSFs auto-organizável e tolerante a falhas para detecção de fogo em áreas de preservação. Para alcançar a auto-organização e a tolerância a falhas incentiva-se as interações locais entre n´os vizinhos que monitoram uma mesma região e a coordenacão de tarefas, por meio de um nó coordenador equipado com um framework para desenvolvimento de aplicações tolerante a falhas baseado em componentes. Utilizando uma técnica de redundância de componentes com abordagem adaptativa, a solucão de detecção de fogo foi implementada. Cada componente, ou seja, diferentes implementações de uma mesma especificação, ´e carregado e descarregado da memória em tempo de execucão enquanto o nó assume o papel de coordenador. Os resultados são armazenados e após execução de todos componentes é obtido um consenso. Para análise e validação do modelo e da aplicação simulou-se 60 eventos na rede de sensores em um cenário real, utilizando o simulador Sinalgo. Os resultados foram classificados como Verdadeiros (parcial ou total) ou Falsos (parcial ou total). Em 45% dos consensos identificou-se uma possível falha na aplicação e somente em 35% houve um consenso total.
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Ostruška, Jan. « Ochrany při zemních spojeních ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221169.

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The thesis deals with wattmetric and conductance principle of faulted feeder detection in medium voltage compensated distribution networks. These principles are analysed and tested with particular emphasis on high impedance earth faults. The first part of testing utilizes data about state of the system with earth fault, which was determined by designed static model of earth fault. The testing in the second part utilizes real records of high impedance earth faults. In both parts the wattmetric and conductance protections was presented on protective relays ABB REF 615, ABB REM 543 and Protection&Consulting RYo by means of unit OMICRON CMC 256plus. As a major result of performed tests are records of detection of particular earth faults. Based on these records it could be concluded, that functionality of protections is substantially dependent on magnitude of zero sequence voltage. Furthermore the wattmetric protections are dependent on fault resistance as well.
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Ковальов, Олексій Іванович, Алексей Иванович Ковалев et O. I. Kovalev. « Підвищення безаварійності та рівня електробезпеки розподільних мереж напругою 6 – 35 кВ кар'єрів ». Thesis, Видавництво НГУ, 2012. http://ir.nmu.org.ua/handle/123456789/148.

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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.03 – "Електротехнічні комплекси та системи". – Державний виший навчальний заклад "Національний гірничий університет", Дніпропетровськ, 2012.
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.09.03 – "Электротехнические комплексы и системы". – Государственное высшее учебное заведение "Национальный горный университет", Днепропетровск, 2012.
Thesis for a candidate of technical science degree by speciality 05.09.03 – "Electrotechnical complexes and systems". State institution of higher education “National Mining University” subject to the Ministry of Education and Science, Youth and Sports of Ukraine, Dnipropetrovs’k, 2012.
Дисертація присвячена розробці принципів і технічних засобів підвищення рівня експлуатаційної надійності і поліпшенню умов електробезпеки в системах електропостачання кар'єрів. Дана характеристика системам електропостачання сучасних залізорудних кар’єрів, розглянуто особливості експлуатації електричних розподільних мереж, виконано аналіз методів контролю ізоляції та засобів захисту. Представлені результати досліджень впливу режиму нейтралі кар'єрних розподільних мереж на якісні та кількісні параметри усталеного і перехідних процесів при замиканнях на землю. З порівняння варіантів заземлення нейтралі встановлено, що найбільш висока експлуатаційна надійність забезпечується в розподільних мережах з резистором в нейтралі. Дано теоретичне обґрунтування методу непрямої оцінки параметрів провідності ізоляції розподільних мереж напругою 6 кВ без зняття робочої напруги. Подані результати дослідження впливу параметрів режиму заземлення нейтралі на працездатність захистів від замикань на землю і на умови електробезпеки. Наведені технічні рішення та рекомендації, що забезпечують підвищення рівня безаварійності та електробезпеки розподільних і живлячих мереж кар'єрів.
Диссертация посвящена разработке принципов и технических средств повышения уровня эксплуатационной надежности и улучшению условий электробезопасности в системах электроснабжения карьеров. Данная характеристика системам электроснабжения современных железорудных карьеров, рассмотрена особенности эксплуатации электрических распределительных сетей, выполнен анализ методов контроля изоляции и средств защиты. Представлены результаты исследований влияния режима заземления нейтрали карьерных распределительных сетей на качественные и количественные параметры установившихся и переходных процессов при замыканиях на землю. Из сравнения вариантов заземления нейтрали установлено, что наиболее высокая эксплуатационная надежность обеспечивается в распределительных сетях с резистором в нейтрали. Дано теоретическое обоснование метода косвенной оценки параметров проводимости изоляции распределительных сетей напряжением 6 кВ без снятия рабочего напряжения, основанного на искусственном изменении величины напряжения смещения нейтрали путем последовательного включения дополнительных тарированных активных проводимостей во все три фазы электроустановки в заданной последовательности. Представлены результаты исследования влияния параметров режима заземления нейтрали на работоспособность защит от замыканий на землю и на условия электробезопасности. Для компенсированных сетей при отсутствии автоматической резонансной настройки режима компенсации рекомендован комбинированный режим заземления нейтрали, который обеспечивает эксплуатационные показатели адекватные системам электроснабжения только с резистором в нейтрали даже при расстройках дугогасящего реактора до 50% от резонансного режима. Показано, что по степени косвенной опасности электрических сетей, работающих с разными режимами нейтрали, предпочтение следует отдать электрическим сетям с резистором в нейтрали. Приведены разработанные технические решения и рекомендации, которые обеспечивают повышение уровня безаварийности и электробезопасности распределительных и живящих сетей карьеров: структура и алгоритм автоматизации процесса косвенного определения полных проводимостей изоляции фаз и их составляющих в трехфазных электрических сетях с изолированной нейтралью напряжением 6-35 кВ с любой степенью несимметрии изоляции; рекомендации по обеспечению селективности защит от замыканий на землю на питающих КРП линиях при двухступенчатой структуре карьерных распределительных сетей; функциональная схема системы избирательной защиты для разветвленных распределительных сетей с компенсированной нейтралью.
The thesis is devoted to development of principles and technical means of increase of an operational reliability level and improvement of electrical safety conditions in power supply systems of open cast mines. The characteristic of power supply systems of modern open cast iron mines is given, the peculiarities of electrical distributive networks operation are considered, the analysis of insulation control methods and protection means are performed. The investigation results of neutral mode influence of open cast mining distributive networks on qualitative and quantitative parameters of steady and transient process in the time of ground fault are presented. From the comparison of neutral grounding options it is determined that highest operational reliability is ensured in distributive networks with resistor in neutral. The theoretical justification of indirect estimation method of insulation conductivity parameters of distributive networks by a voltage 6 kV without switching-off of a working voltage is given. The investigation results of grounding neutral mode parameters influence on the operability of ground fault protection and electrical safety conditions are given. The technical solutions and recommendations that provide the level increase of trouble-free operation and electrical safety of distributive and supplying networks of open cast mines are presented.
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Sattouf, Mousa. « Systém snímání dat a ovládání vodní elektrárny prostřednictvím internetové techniky ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-233685.

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Vodní energie se nyní stala nejlepším zdrojem elektrické energie na zemi. Vyrábí se pomocí energie poskytované pohybem nebo pádem vody. Historie dokazuje, že náklady na tuto elektrickou energii zůstávají konstantní v průběhu celého roku. Vzhledem k mnoha výhodám, většina zemí nyní využívá vodní energie jako hlavní zdroj pro výrobu elektrické energie.Nejdůležitější výhodou je, že vodní energie je zelená energie, což znamená, že žádné vzdušné nebo vodní znečišťující látky nejsou vyráběny, také žádné skleníkové plyny jako oxid uhličitý nejsou vyráběny, což činí tento zdroj energie šetrný k životnímu prostředí. A tak brání nebezpečí globálního oteplování. Použití internetové techniky k ovladání několika vodních elektráren má velmi významné výhody, jako snížení provozních nákladů a flexibilitu uspokojení změny poptávky po energii na straně spotřeby. Také velmi efektivně čelí velkým narušením elektrické sítě, jako je například přidání nebo odebrání velké zátěže, a poruch. Na druhou stranu, systém získávání dat poskytuje velmi užitečné informace pro typické i vědecké analýzy, jako jsou ekonomické náklady, predikce poruchy systémů, predikce poptávky, plány údržby, systémů pro podporu rozhodování a mnoho dalších výhod. Tato práce popisuje všeobecný model, který může být použit k simulaci pro sběr dat a kontrolní systémy pro vodní elektrárny v prostředí Matlab / Simulink a TrueTime Simulink knihovnu. Uvažovaná elektrárna sestává z vodní turbíny připojené k synchronnímu generátoru s budicí soustavou, generátor je připojen k veřejné elektrické síti. Simulací vodní turbíny a synchronního generátoru lze provést pomocí různých simulačních nástrojů. V této práci je upřednostňován SIMULINK / MATLAB před jinými nástroji k modelování dynamik vodní turbíny a synchronního stroje. Program s prostředím MATLAB SIMULINK využívá k řešení schematický model vodní elektrárny sestavený ze základních funkčních bloků. Tento přístup je pedagogicky lepší než komplikované kódy jiných softwarových programů. Knihovna programu Simulink obsahuje funkční bloky, které mohou být spojovány, upravovány a modelovány. K vytvoření a simulování internetových a Real Time systémů je možné použít bud‘ knihovnu simulinku Real-Time nebo TRUETIME, v práci byla použita knihovna TRUETIME.
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33

Quiroga, Jabid Eduardo Mendez. « Stator winding fault detection for a PMSM using fuzzy logic classifier and neural network model identification ». 2008. http://etd.lib.fsu.edu/theses/available/etd-04282008-100002.

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Thesis (M.S.)--Florida State University, 2008
Advisor: Dave A. Cartes, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed June 11, 2008). Document formatted into pages; contains xii, 82 pages. Includes bibliographical references.
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Lin, Yi-Shin, et 林宜生. « Applications of Cerebellar Model Articulation Controller Neural Network on Fault Diagnosis of Mechanical and Electrical Equipments ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/21878328631104500839.

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碩士
國立勤益科技大學
資訊與電能科技研究所
95
The objective of this thesis is to study the applications of cerebellar model articulation controller (CMAC) neural network on the fault diagnosis of mechanical and electrical equipments. To demonstrate the feasibility of the proposed scheme, we take water circulation system and steam turbine generator sets as examples. Depending on the pstterns collection of each possible fault type, we built the diagnosis architecture based on the CAMC neural network firstly. Then a steepest descent learning rule is used to train the diagnosis system until the cost function smaller than a small positive value. Finally, the diagnosis system can be used to diagnose the fault types of water circulation system or turbine generator system. In the case study, the diagnosis results demonstrated the proposed scheme outperforms than traditional schemes on the correctness, noise rejection ability and the learning speed. In this thesis, the proposed diagnosis system is implemented on a personal computer and microcontroller system simultaneously. On the personal computer, the user can input the diagnosed data by a friendly interface and obtain the diagnosis results. Also, a remote fault diagnosis web site is built in our laboratory to benefit the data collection and diagnosis test for remote users. On the microcontroller system, a portable diagnosis apparatus is implemented to benefit the fault diagnosis on the work field. All the necessary technology described above will be discussed in the thesis.
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35

Yang, Kai-jie, et 楊凱木疌. « Recurrent Fuzzy Neural Cerebellar Model Articulation Network Fault-Tolerant Control of Six-Phase PMSM Position Servo Drive ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/5j2yh7.

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碩士
國立中央大學
電機工程學系
102
A DSP-based recurrent fuzzy neural cerebellar model articulation network (RFNCMAN) fault-tolerant control of a six-phase PMSM position servo drive system is proposed in this study. First, the fault detection and operating decision method of the six-phase PMSM position servo drive is developed. Then, an ideal computed torque controller is designed for the tracking of the rotor position reference command first. Since the uncertainties of the six-phase PMSM position servo drive system are difficult to know in advance, it is impossible to design an idea computed control law for practical application. Therefore, one method is that the RFNCMAN is proposed to mimic the ideal computed torque controller with a compensated controller to eliminate the approximation error. The other method is that the RFNCMAN is proposed to estimate a nonlinear equation included in the idea computed control law with a robust compensator designed to compensate the minimum reconstructed error. In the RFNCMAN, a recurrent fuzzy cerebellar model articulation network (RFCMAN) is adopted in the first dimension to enhance the online learning rate and localization learning capability. Moreover, a general recurrent fuzzy neural network (RFNN) is adopted in the second dimension to enhance the generalization performance and to reduce the required memory and rule numbers. Finally, the proposed fault-tolerant position control system is implemented in a 32-bit floating-point DSP. The effectiveness of the proposed RFNCMAN fault-tolerant control for the six-phase PMSM position servo drive system is verified by some experimental results.
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STEFANNI, Francesco. « A design and verification methodology for networked embedded systems ». Doctoral thesis, 2011. http://hdl.handle.net/11562/350704.

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Oggigiorno i Sistemi Dedicati di Rete (Networked Embeddedd Systems – NES) sono una tecnologia pervasiva. Il loro utilizzo comprende applicazioni per il monitoraggio, per l’automazione delle case, e per compiti in ambienti critici. La loro crescente complessità richiede nuove metodologie per poter effettuare efficientemente le fasi di progettazione e verifica. Questo lavoro presenta un flusso di sviluppo generico per NES, supportato dall’implementazione di programmi per la loro applicazione. Il flusso di sviluppo sfrutta il linguaggio SystemC, e considera la rete come una dimensione dello spazio di progetto. La metodologia di base comprende estensioni per considerare anche i casi in cui il NES sia implementato usando un middleware o in cui siano presenti dei requisiti di affidabilità. Inoltre, sono stati implementati dei programmmi di traduzione per consentire l’adozione della metodologia proposta con design scritti in altri linguaggi per la descrizione dell'hardware.
Nowadays, Networked Embedded Systems (NES’s) are a pervasive technology. Their use ranges from communication, to home automation, to safety critical fields. Their increasing complexity requires new methodologies for efficient design and verification phases. This work presents a generic design flow for NES’s, supported by the implementation of tools for its application. The design flow exploits the SystemC language, and considers the network as a design space dimension. Some extensions to the base methodology have been performed to consider the presence of a middleware as well as dependability requirements. Translation tools have been implemented to allow the adoption of the proposed methodology with designs written in other HW description languages.
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37

Liao, Kao-Chin, et 廖高進. « Application of Cerebellar Model Articulation Controller Based on Neural Network for Fault Diagnosis of the Cable’s Air Leakage ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/19582247640291570795.

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碩士
逢甲大學
資訊電機工程碩士在職專班
94
The user''s circuit cable of Chunghwa Telecom Company is adopted the electric cable cover with full air to avoid the outside moisture to permeate the inside of cable. And it also can be used in faulty diagnosis according to the interior pressure value. The circuit cables is adopted the simple mathematic calculation or pressure gradient to diagnose the site of air leakage of cable. But the both ways are often misjudgment to make the maintenance workers busy with nothing. It''s waste time and manpower, in case of cable is serious damaged and mass air leakage didn''t disposal immediately, then moisture permeate the core of cable to make the insulation destroy and 3200 users cables out of order, it will effect the whole circuit cables quality and clients advantage. The pressure gradient diagnosis application cannot judge the air leakage in terminal of air able. But also the air pressure transducer to measure the pressure has too bigger error of value. Then make the diagnosis difficult and cause the result of judgment mistake. So in this thesis, we suggest the cerebellar model articulation controller (CMAC) neural network to judge site of air leakage for air cable. Because of it’s capable to make associative memory and acceptance in error tolerance. But the training process can avoid the weights interference problem. So it can be accurate to find the site of air leakage when the air cable is out of order. Then it can improve the judgment result of pressure gradient diagnosis.
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38

Lin, Wen-Lang, et 林文郎. « Application of Cerebellar Model Articulation Controller Based on Neural Network for Fault Diagnoses of the Steam Turbine-Generators and the Condensers in Fossil-Fuel Powerplants ». Thesis, 2004. http://ndltd.ncl.edu.tw/handle/79105970291524266643.

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碩士
逢甲大學
電機工程所
92
In this paper, a cerebellar model articulation controller (CMAC) neural network application to fault diagnosis is proposed. This novel fault diagnosis system contains an input layer, quantization layer, binary coding layer, and fired up memory addresses coding unit. Firstly, we construct the configuration of diagnosis system depending on the fault patterns. Then, the known fault patterns are used to train the neural network. Finally, the diagnosis system diagnoses the fault types. Utilizing all the characteristic of self-learning, association and generalization, like the cerebellum of human being, the proposed CMAC neural network fault diagnosis scheme enables a powerful, straightforward, and efficient fault diagnosis. Furthermore, the following merits are obtained: high learning and diagnosis speed, high noise rejection ability, alleviating the dependency to expert’s expertise, eliminating the weights interference between different fault type patterns, memory size reduction by new excited addresses coding technique, and ability to fault diagnosis system of more layers.
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39

« A high speed fault-tolerant multimedia network and connectionless gateway for ATM networks ». 1997. http://library.cuhk.edu.hk/record=b5889329.

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by Patrick Lam Sze Fan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1997.
Includes bibliographical references (leaves 163-[170]).
Chapter 1 --- Introduction --- p.1
Chapter 2 --- Fault-tolerant CUM LAUDE NET --- p.7
Chapter 2.1 --- Overview of CUM LAUDE NET --- p.7
Chapter 2.2 --- Network architecture of CUM LAUDE NET --- p.8
Chapter 2.3 --- Design of Router-node --- p.10
Chapter 2.3.1 --- Architecture of the Router-node --- p.10
Chapter 2.3.2 --- Buffers Arrangement of the Router-node --- p.12
Chapter 2.3.3 --- Buffer transmission policies --- p.13
Chapter 2.4 --- Protocols of CUM LAUDE NET --- p.14
Chapter 2.5 --- Frame Format of CUM LAUDE NET --- p.15
Chapter 2.6 --- Fault-tolerant (FT) and Auto-healing (AH) algorithms --- p.16
Chapter 2.6.1 --- Overview of the algorithms --- p.16
Chapter 2.6.2 --- Network Failure Scenarios --- p.18
Chapter 2.6.3 --- Design and Implementation of the Fault Tolerant Algorithm --- p.19
Chapter 2.6.4 --- Design and Implementation of the Auto Healing Algorithm --- p.26
Chapter 2.6.5 --- Network Management Signals and Restoration Times --- p.27
Chapter 2.6.6 --- Comparison of fault-tolerance features of other networks with the CUM LAUDE NET --- p.31
Chapter 2.7 --- Chapter Summary --- p.31
Chapter 3 --- Overview of the Asynchronous Transfer Mode (ATM) --- p.33
Chapter 3.1 --- Introduction --- p.33
Chapter 3.2 --- ATM Network Interfaces --- p.34
Chapter 3.3 --- ATM Virtual Connections --- p.35
Chapter 3.4 --- ATM Cell Format --- p.36
Chapter 3.5 --- ATM Address Formats --- p.36
Chapter 3.6 --- ATM Protocol Reference Model --- p.38
Chapter 3.6.1 --- The ATM Layer --- p.39
Chapter 3.6.2 --- The ATM Adaptation Layer --- p.39
Chapter 3.7 --- ATM Signalling --- p.44
Chapter 3.7.1 --- ATM Signalling Messages and Call Setup Procedures --- p.45
Chapter 3.8 --- Interim Local Management Interface (ILMI) --- p.47
Chapter 4 --- Issues of Connectionless Gateway --- p.49
Chapter 4.1 --- Introduction --- p.49
Chapter 4.2 --- The Issues --- p.50
Chapter 4.3 --- ATM Internetworking --- p.51
Chapter 4.3.1 --- LAN Emulation --- p.52
Chapter 4.3.2 --- IP over ATM --- p.53
Chapter 4.3.3 --- Comparing IP over ATM and LAN Emulation --- p.59
Chapter 4.4 --- Connection Management --- p.61
Chapter 4.4.1 --- The Indirect Approach --- p.62
Chapter 4.4.2 --- The Direct Approach --- p.63
Chapter 4.4.3 --- Comparing the two approaches --- p.64
Chapter 4.5 --- Protocol Conversion --- p.65
Chapter 4.5.1 --- Selection of Protocol Converter --- p.68
Chapter 4.6 --- Packet Forwarding Modes --- p.68
Chapter 4.7 --- Bandwidth Assignment --- p.70
Chapter 4.7.1 --- Bandwidth Reservation --- p.71
Chapter 4.7.2 --- Fast Bandwidth Reservation --- p.72
Chapter 4.7.3 --- Bandwidth Advertising --- p.72
Chapter 4.7.4 --- Bandwidth Advertising with Cell Drop Detection --- p.73
Chapter 4.7.5 --- Bandwidth Allocation on Source Demand --- p.73
Chapter 4.7.6 --- The Common Problems --- p.74
Chapter 5 --- Design and Implementation of the Connectionless Gateway --- p.77
Chapter 5.1 --- Introduction --- p.77
Chapter 5.1.1 --- Functions Definition of Connectionless Gateway --- p.79
Chapter 5.2 --- Hardware Architecture of the Connectionless Gateway --- p.79
Chapter 5.2.1 --- Imposed Limitations --- p.82
Chapter 5.3 --- Software Architecture of the Connectionless Gateway --- p.83
Chapter 5.3.1 --- TCP/IP Internals --- p.84
Chapter 5.3.2 --- ATM on Linux --- p.85
Chapter 5.4 --- Network Architecture --- p.88
Chapter 5.4.1 --- IP Addresses Assignment --- p.90
Chapter 5.5 --- Internal Structure of Connectionless Gateway --- p.90
Chapter 5.5.1 --- Protocol Stacks of the Gateway --- p.90
Chapter 5.5.2 --- Gateway Operation by Example --- p.93
Chapter 5.5.3 --- Routing Table Maintenance --- p.97
Chapter 5.6 --- Additional Features --- p.105
Chapter 5.6.1 --- Priority Output Queues System --- p.105
Chapter 5.6.2 --- Gateway Performance Monitor --- p.112
Chapter 5.7 --- Setup an Operational ATM LAN --- p.117
Chapter 5.7.1 --- SVC Connections --- p.117
Chapter 5.7.2 --- PVC Connections --- p.119
Chapter 5.8 --- Application of the Connectionless Gateway --- p.120
Chapter 6 --- Performance Measurement of the Connectionless Gateway --- p.121
Chapter 6.1 --- Introduction --- p.121
Chapter 6.2 --- Experimental Setup --- p.121
Chapter 6.3 --- Measurement Tools of the Experiments --- p.123
Chapter 6.4 --- Descriptions of the Experiments --- p.124
Chapter 6.4.1 --- Log Files --- p.125
Chapter 6.5 --- UDP Control Rate Test --- p.126
Chapter 6.5.1 --- Results and analysis of the UDP Control Rate Test --- p.127
Chapter 6.6 --- UDP Maximum Rate Test --- p.138
Chapter 6.6.1 --- Results and analysis of the UDP Maximum Rate Test --- p.138
Chapter 6.7 --- TCP Maximum Rate Test --- p.140
Chapter 6.7.1 --- Results and analysis of the TCP Maximum Rate Test --- p.140
Chapter 6.8 --- Request/Response Test --- p.144
Chapter 6.8.1 --- Results and analysis of the Request/Response Test --- p.144
Chapter 6.9 --- Priority Queue System Verification Test --- p.149
Chapter 6.9.1 --- Results and analysis of the Priority Queue System Verifi- cation Test --- p.150
Chapter 6.10 --- Other Observations --- p.153
Chapter 6.11 --- Solutions to Improve the Performance --- p.154
Chapter 6.12 --- Future Development --- p.157
Chapter 7 --- Conclusion --- p.158
Bibliography --- p.163
A List of Publications --- p.171
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Somers, Caedmon David Austen. « Fault detection in cable modem networks ». 2004. http://hdl.handle.net/1828/518.

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Zhong, Jing. « A new fault model and its application in synthesizing Toffoli networks ». Thesis, 2008. http://hdl.handle.net/1828/1236.

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Reversible logic computing is a rapidly developing research area. Both reversible logic synthesis and testing reversible logic circuits are very important issues in this area. In this thesis, we present our work in these two aspects. We consider a new fault model, namely the crosspoint fault, for reversible circuits. The effects of this kind of fault on the behaviour of the circuits are studied. A randomized test pattern generation algorithm targeting this kind of fault is introduced and analyzed. The relationship between the crosspoint faults and stuck-at faults is also investigated. The crosspoint fault model is then studied for possible applications in reversible logic synthesis. One type of redundancy exists in Toffoli networks in the form of undetectable multiple crosspoint faults. So redundant circuits can be simplified by deleting those undetectable faults. The testability of multiple crosspoint faults is analyzed in detail. Several important properties are proved and integrated into the simplifying algorithm so as to speed up the process. We also provide an optimized implementation of a Reed-Muller spectra based reversible logic synthesis algorithm. This new implementation uses a compact form of the Reed-Muller spectra table of the specified reversible function to save memory during execution. Experimental results are presented to illustrate the significant improvement of this new implementation.
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42

Yang, Ming Hao, et 楊明豪. « A euler-path based model for fault-tolerant multicasting in wormhole-routed networks ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/53841827136054321536.

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43

Cholette, Michael Edward. « Performance monitoring and fault-tolerant control of complex systems with variable operating conditions ». Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6068.

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Ensuring the reliable operation of engineering systems has long been a subject of great practical and academic interest. This interest is clearly demonstrated by the preponderance of literature in the area of Fault Detection and Diagnosis (FDD) and Fault Tolerant Control (FTC), spanning the past three decades. However, increasingly stringent performance and safety requirements have led to engineering systems with progressively increasing complexity. This complexity has rendered many traditional FDD and FTC methods exceedingly cumbersome, often to the point of infeasibility. This thesis aims to enable FDD and FTC for complex engineering systems of interacting dynamic subsystems. For such systems, generic FDD/FTC methods have remained elusive. Effects caused by nonlinearities, interactions between subsystems and varying usage patterns complicate FDD and FTC. The goal of this thesis is to develop methods for FDD and FTC that will allow decoupling of anomalies occurred inside the monitored system from those occurred in the systems affecting the monitored system, as well as enabling performance recovery of the monitored system. In pursuit of these goals, FDD and FTC methods are explored that can account for operating regime-dependent effects in monitoring, diagnosis, prognosis and performance recovery for two classes of machines: those that operate in modes that can change only at distinct times (which often occur in manufacturing opera- tions such as drilling, milling, turning) and for those that operate in regimes that are continuously varying (such as automotive systems or electric motors). For machines that operate in modes that can change only at distinct times, a degradation model is postulated which describes how the system degrades over time for each operating regime. Using the framework of Hidden Markov Models (HMMs), modeling and identification tools are developed that enable identification a HMM of degradation for each machine operation. In the sequel, monitoring and prognosis methods that naturally follow from the framework of HMMs are also presented. The modeling and monitoring methodology is then applied to a real-world semiconductor manufacturing process using data provided by a major manufacturer. For machines that operate in regimes that are continuously varying, a behavioral model is postulated that describes the input-output dynamics of the nor- mal system in different operating regimes. Monitoring methods are presented that have the capability to account for operating regime-dependent modeling accuracies and isolate faults that have not been anticipated and for which no fault models are available. By conducting fault detection in a regime-dependent fashion, changes in modeling errors that are due to operating regime changes can be successfully distinguished from changes that are due to truly faulty operation caused by changes in the system dynamics. Enabled by this, unanticipated faults can be isolated through proliferation of the fault detection through the various subsystems of the anoma- lous system. The FDD methodology is applied to detect and diagnose faults for a multiple-input multiple-output Exhaust Gas Recirculation system in a diesel engine. Finally, methods to facilitate the recovery of normal system behavior are detailed. Using the same local model structure that was pursued for behavioral models, it is envisioned that the nominal controller will be reconfigured to attempt to recover nominal behavior as much as possible. To enable this reconfiguration, methods for automated design of closed-loop controllers for the local modeling structure are presented. Using a model-predictive approach with rigorous stability considerations, it is shown that the controllers can track a reference trajectory. Such a trajectory could be generated by any model that satisfies the control objectives, for normal or faulty systems. The controllers are then demonstrated on a benchmark nonlinear system that is nonlinear in the control.
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« Model Predictive Control of Complex Systems including Fault Tolerance Capabilities : Application to Sewer Networks ». Universitat Politècnica de Catalunya, 2007. http://www.tesisenxarxa.net/TDX-0515107-122518/.

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45

Kabir, Sohag, M. Walker et Y. Papadopoulos. « Dynamic system safety analysis in HiP-HOPS with Petri Nets and Bayesian Networks ». 2018. http://hdl.handle.net/10454/17426.

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Yes
Dynamic systems exhibit time-dependent behaviours and complex functional dependencies amongst their components. Therefore, to capture the full system failure behaviour, it is not enough to simply determine the consequences of different combinations of failure events: it is also necessary to understand the order in which they fail. Pandora temporal fault trees (TFTs) increase the expressive power of fault trees and allow modelling of sequence-dependent failure behaviour of systems. However, like classical fault tree analysis, TFT analysis requires a lot of manual effort, which makes it time consuming and expensive. This in turn makes it less viable for use in modern, iterated system design processes, which requires a quicker turnaround and consistency across evolutions. In this paper, we propose for a model-based analysis of temporal fault trees via HiP-HOPS, which is a state-of-the-art model-based dependability analysis method supported by tools that largely automate analysis and optimisation of systems. The proposal extends HiP-HOPS with Pandora, Petri Nets and Bayesian Networks and results to dynamic dependability analysis that is more readily integrated into modern design processes. The effectiveness is demonstrated via application to an aircraft fuel distribution system.
Partly funded by the DEIS H2020 project (Grant Agreement 732242).
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46

Chen, Shi-Can, et 陳詩燦. « Fault Diagnosis of Dual-Buck Bidirectional DC-AC Converter Based on Cerebellar Model Neural Networks ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5h4xds.

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碩士
元智大學
電機工程學系
106
With the vigorous development of new energy generation and green intelligent electricity utilization, more and more power electronic converters are applied to smart power grid and become the key to energy transformation. As the core of energy conversion, the failure of power electronic converters may cause the whole system to fail or even paralyze, and result in serious losses. Therefore, it is very important to study the fault diagnosis method of converter circuit in depth; predict the fault risk with the aid of intelligent diagnosis method; realize intelligent, fast and accurate diagnosis of the fault type of power electronic converter; locate fault components; replace fault components in advance; and ensure the reliability and stability of the system operation. Based on the fault characteristics of power electronic converter circuit, the fault diagnosis and location of converter circuit are studied in this thesis. By analyzing the overall output signal of the converter circuit, the methods of fault feature extraction, fault diagnosis and location are studied. The main research is as follows: (1) A fault feature extraction method of converter circuit based on fast Fourier transform is studied. First, the fault features are extracted by fast Fourier transform, and fault feature vector is formed. On this basis, using principal component analysis method to further screen the fault feature vectors, extracting the principal components of the feature vector that can represent the operating state of the converter circuit, reduce the redundant fault features, and reduce the data dimension. (2)Proposed a kind of intelligent fault diagnosis methods with high diagnostic accuracy and high speed—based on cerebellar model neural network (CMNN) fault diagnosis method of the converter circuit. By using the back-propagation algorithm to update neural network parameters, the CMNN can make the diagnosis error converge quickly. After off-line training, the CMNN diagnosis unit can accurately identify the type of circuit fault and the specific fault location through fault features, then it can obtain accurate diagnosis results. (3) Aiming at the disadvantages of poor initial parameter selection, which has great influence on the learning ability of neural network diagnostics, a global optimization search method, Genetic Algorithm, is used to optimize the initial weights of neural network to obtain better initial parameters. Through further training, the neural network internal parameters (weights, deviations) are approached faster and more accurate toward the value that produces the smallest error. (4) Taking the dual-buck bidirectional DC-AC converter circuit as an example, the fault diagnosis simulation of the converter circuit is carried out. The equivalent model of components that is prone to parametric faults is established, and set different levels of fault types. Under different working conditions, the performance of the fault diagnosis unit based on the CMNN for the parametric fault diagnosis of dual-buck bidirectional DC-AC converter circuit is simulated. The diagnostic results are compared with the that using a traditional BP neural network diagnostic unit. The comparison results show that the proposed fault diagnosis method can identify fault types more quickly and has higher diagnostic accuracy.
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47

Tai-LingYe et 葉泰麟. « A Study of Precise Fault Diagnosis Algorithms for Hypercube-Like Networks Based on the Comparison Diagnosis Model ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2qejqn.

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博士
國立成功大學
資訊工程學系
105
With the rapid development of technology, multiprocessor systems may contain hundreds or even thousands of processors (nodes) that communicate by exchanging messages through an interconnection network. Fault-tolerance computing is important for a massively parallel processing system and the reliability of processors in it is therefore becoming an important issue. In order to maintain high system reliability, whenever a processor is found faulty, it should be replaced by a fault-free processor. The technique of identifying faulty processors by constructing tests on the processors and interpreting the outcomes is known as fault diagnosis. The precise fault diagnosis diagnoses all processors correctly. In the comparison diagnosis model, it allows a processor to perform diagnosis by contrasting the responses from a pair of neighboring processors through sending the identical assignment. Under the comparison diagnosis model, Sengupta and Dahbura put forward the MM* model and also designed a O(N5)-time precise fault diagnosis algorithm to diagnose faulty processors for general topologies by using the MM* model, where N is the number of processors in multiprocessor systems. In this thesis, we devised a O(N(log2 N)2)-time precise fault diagnosis algorithm to diagnose all faulty processors for hypercube-like networks by using the MM* model. Based on the Hamiltonian cycle properties, we improved the aforementioned results by presenting a O(N)-time precise fault diagnosis algorithm to diagnose all faulty processors for hypercube-like networks by using the MM* model. Applying our algorithms, the faulty processors in n-dimensional hypercubes, ndimensional crossed cubes, n-dimensional M¨obius cubes, n-dimensional generalized twisted cubes, n-dimensional twisted cubes, n-dimensional locally twisted cubes, and recursive circulants can all be diagnosed in linear time.
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48

Perera, Nuwan. « Detection, Localization, and Recognition of Faults in Transmission Networks Using Transient Currents ». 2012. http://hdl.handle.net/1993/8867.

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The fast clearing of faults is essential for preventing equipment damage and preserving the stability of the power transmission systems with smaller operating margins. This thesis examined the application of fault generated transients for fast detection and isolation of faults in a transmission system. The basis of the transient based protection scheme developed and implemented in this thesis is the fault current directions identified by a set of relays located at different nodes of the system. The direction of the fault currents relative to a relay location is determined by comparing the signs of the wavelet coefficients of the currents measured in all branches connected to the node. The faulted segment can be identified by combining the fault directions identified at different locations in the system. In order to facilitate this, each relay is linked with the relays located at the adjacent nodes through a telecommunication network. In order to prevent possible malfunctioning of relays due to transients originating from non-fault related events, a transient recognition system to supervise the relays is proposed. The applicability of different classification methods to develop a reliable transient recognition system was examined. A Hidden Markov Model classifier that utilizes the energies associated with the wavelet coefficients of the measured currents as input features was selected as the most suitable solution. Performance of the protection scheme was evaluated using a high voltage transmission system simulated in PSCAD/EMTDC simulation software. The custom models required to simulate the complete protection scheme were implemented in PSCAD/EMTDC. The effects of various factors such as fault impedance, signal noise, fault inception angle and current transformer saturation were investigated. The performance of the protection scheme was also tested with the field recorded signals. Hardware prototypes of the fault direction identification scheme and the transient classification system were implemented and tested under different practical scenarios using input signals generated with a real-time waveform playback instrument. The test results presented in this thesis successfully demonstrate the potential of using transient signals embedded in currents for detection, localization and recognition of faults in transmission networks in a fast and reliable manner.
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49

Islam, Fariha. « An Investigation of the First-Order Mechanics of Polygonal Fault Networks of Utopia Planitia, Mars ». 2009. https://scholarworks.umass.edu/theses/225.

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This study investigates the first-order mechanics of polygonal fault networks in Utopia Planitia, Mars and whether terrestrial sedimentary basin polygonal terrains are an analog for giant Martian polygons since there is an overlap in scale between the 3 km terrestrial polygons and the 1-40 km giant polygons of Mars. Volumetric contraction accommodates the extensional faulting observed in both cases. Boundary Element Method numerical models are used to simulate the first-order-mechanics of the faulting process. Models use material properties for wet, fine sediment, and apply an extensional strain to produce volumetric contraction. Fracture seeds that simulate the buried topography beneath the basin are placed at the base of the model. MOLA tracks from the Highlands are used to create the uneven topography beneath the basin since the underlying topography of the Northern Lowlands is thought to be similar to the topography of the older, Southern Highlands. The model investigates whether 1 & 2 km layer of wet, fine sediments will produce the fracture spacing observed within the polygonal terrains in Utopia (~5 – 6.5 km). A fracture network that is similar to the scale of the polygonal terrain in the Utopia Basin is established within the model at low strain, supporting the idea that buried topography could be the primary scaling factor for the polygon grabens. The results do not constrain an upper limit for strain; the observed trough widths in Utopia suggest that further strain was expressed by the widening of the troughs. Material properties for wet, fine sediments, analogous to the terrestrial counterpart, are appropriate for the model to match what is observed in Utopia. The power-law scale of Highlands topography controls the scale of the surface fracture spacing in the models. Measurements of running average of trough spacing along radial transects with respect to the center of the basin did not yield a monotonic decrease in trough spacing as would be expected for a smooth basement with no buried topography. Study results support the case for buried topography controlling the scale of the giant polygons of Utopia Planitia.
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Raposo, Duarte Miguel Garcia. « Monitoring Industrial Wireless Sensor Networks : A model to enhance Security and Reliability ». Doctoral thesis, 2020. http://hdl.handle.net/10316/88841.

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Tese no âmbito do Programa de Doutoramento em Ciências e Tecnologias da Informação e apresentada ao Departamento de Engenharia Informática da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
A new generation of industrial systems are growing, in a new industrial evolution that connects wireless technologies with powerful devices, capable to make their own decisions. In the Industry 4.0 paradigm, industrial systems are becoming more powerful and complex in order to keep with the requirements needed to build Cyber Physical Systems (CPSs). To achieve such paradigm, Industrial Wireless Sensor Networks (IWSNs) are a key-technology capable to achieve micro-intelligence, with low-cost, and mobility, reducing even further today’s already short production cycles, and at the same time allowing new industrial applications. Specifically, in the last decade, more reliable and deterministic standards were proposed, all of them sharing the same base technology, the IEEE802.15.4 standard. At the same time, until now, Industrial Control Systems (ICSs) have remained disconnected from the Internet, relying in the airgap principle to ensure security. Nevertheless, there is a lack of post-deployment tools to monitor technologies like the WirelessHART, ISA100.11a, WIA-PA and the ZigBee standards, contrary to what happens with most common wired technologies. The lack of these tools can be explained by several characteristics present in current IoT devices like the fragmentation of the operating systems, the need to develop specific firmware for each application, different hardware architectures; etc. Thus, in this thesis, and looking for the current challenges of industrial IoT technologies, a monitoring model is proposed, capable not only to monitor current industrial networks based on the IEEE802.15.4 standard, but also the in-node components of sensor nodes, in several hardware and firmware architectures. The proposed architecture explores several techniques to obtain free monitoring metrics; agents in charge of processing these metrics; and relies in management standards to share all the monitoring information. To prove the performance of this proposal, a WirelessHART testbed was built, as well as the different components presented in the architectural model. Additionally, using representative anomalies, injected in a WirelessHART testbed, an Anomaly Detection system capable to detect network anomalies and security attacks was built, proving the effectiveness of the presented model in the network perspective. In the same way, in order to prove the effectiveness in the detection of firmware and hardware anomalies, an Anomaly Detection system for in-node components was also built. The two Anomaly Detection systems were able to detect with high recall and low false positive ratio the anomalies inserted in the systems, proving that the proposed model can be used as a post-deployment tool in real industrial scenarios.
Atualmente assiste-se a uma nova geração de sistemas industriais, numa evolução que junta tecnologias sem fios com dispositivos embebidos, cada vez mais inteligentes e capazes. No âmbito da Indústria 4.0, os sistemas industriais tornaram-se mais potentes e complexos, em resposta aos requisitos impostos pelos novos Sistemas Ciber-Físicos. No panorama atual, as Redes de Sensores Sem Fios Industriais são uma tecnologia-chave, capaz de fornecer micro-inteligência, e mobilidade, a um baixo-custo, reduzindo cada vez mais os ciclos de produção industrial, e permitindo novos tipos de aplicações. Por esta razão, durante a última década, várias tecnologias baseadas na norma IEEE802.15.4 foram desenvolvidas e propostas, oferecendo técnicas de transmissão mais fiáveis e determinísticas. Ainda, no domínio da segurança, assistimos também a uma mudança de paradigma neste tipo de sistemas. O paradigma utilizado até então, regia-se através de políticas de segurança que privilegiavam o isolamento. Porém, a conexão destes sistemas à Internet origina um novo conjunto de ameaças externas, que tem crescido progressivamente. De modo a manter a fiabilidade, as ferramentas de monitorização em ambiente de produção permitem uma constante monitorização dos sistemas, prevenindo eventuais falhas. Contudo, existe uma ausência de ferramentas para normas como o WirelessHART, ISA100.11a, WIA-PA e ZigBee, ao contrário do que acontece no caso das tecnologias legadas. Esta lacuna pode ser explicada pelas diferentes características presentes nos dispositivos IoT, como por exemplo, a fragmentação dos sistemas operativos, a necessidade de desenvolver firmware específico para cada aplicação, e os diferentes tipos de arquitecturas de hardware existentes. O trabalho desenvolvido nesta tese, apresenta um novo modelo de arquitetura de monitorização, não só capaz de monitorizar as tecnologias industriais baseadas na norma IEEE802.15.4, como também os próprios componentes internos dos nós-sensores (em diferentes arquiteturas de firmware e hardware). O modelo de arquitetura proposto apresenta técnicas que permitem obter métricas de estado sem custos, partilhadas através de protocolos de gestão, por agentes responsáveis pela respetiva aquisição. Para confirmar o baixo impacto da arquitetura proposta foi criada uma testbed utilizando a norma WirelessHART, com todos os agentes. Adicionalmente, para provar a eficácia e utilidade da arquitetura foram desenvolvidos dois sistemas de deteção de anomalias: o primeiro permite a deteção de anomalias de rede; e o segundo possibilita a deteção de anomalias no firmware e hardware nos nós-sensores. Estes sistemas foram avaliados, através da injeção de anomalias de rede, firmware e hardware. Os dois sistemas de deteção propostos conseguiram identificar os comportamentos anómalos com alto recall e baixo false positive ratio, provando assim, que o modelo proposto poderá ser utilizado como ferramenta de diagnóstico em redes de sensores sem fios industriais.
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