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Guardalben, Lucas. "Communication between nodes for autonomic and distributed management." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/12877.
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Doutoramento conjunto MAPi em InformáticaOver the last decade, the most widespread approaches for traditional management were based on the Simple Network Management Protocol (SNMP) or Common Management Information Protocol (CMIP). However, they both have several problems in terms of scalability, due to their centralization characteristics. Although the distributed management approaches exhibit better performance in terms of scalability, they still underperform regarding communication costs, autonomy, extensibility, exibility, robustness, and cooperation between network nodes. The cooperation between network nodes normally requires excessive overheads for synchronization and dissemination of management information in the network. For emerging dynamic and large-scale networking environments, as envisioned in Next Generation Networks (NGNs), exponential growth in the number of network devices and mobile communications and application demands is expected. Thus, a high degree of management automation is an important requirement, along with new mechanisms that promote it optimally and e ciently, taking into account the need for high cooperation between the nodes. Current approaches for self and autonomic management allow the network administrator to manage large areas, performing fast reaction and e ciently facing unexpected problems. The management functionalities should be delegated to a self-organized plane operating within the network, that decrease the network complexity and the control information ow, as opposed to centralized or external servers. This Thesis aims to propose and develop a communication framework for distributed network management which integrates a set of mechanisms for initial communication, exchange of management information, network (re) organization and data dissemination, attempting to meet the autonomic and distributed management requirements posed by NGNs. The mechanisms are lightweight and portable, and they can operate in di erent hardware architectures and include all the requirements to maintain the basis for an e cient communication between nodes in order to ensure autonomic network management. Moreover, those mechanisms were explored in diverse network conditions and events, such as device and link errors, di erent tra c/network loads and requirements. The results obtained through simulation and real experimentation show that the proposed mechanisms provide a lower convergence time, smaller overhead impact in the network, faster dissemination of management information, increase stability and quality of the nodes associations, and enable the support for e cient data information delivery in comparison to the base mechanisms analyzed. Finally, all mechanisms for communication between nodes proposed in this Thesis, that support and distribute the management information and network control functionalities, were devised and developed to operate in completely decentralized scenarios.
Durante a última década, protocolos como Simple Network Management Protocol (SNMP) ou Common Management Information Protocol (CMIP) foram as abordagens mais comuns para a gestão tradicional de redes. Essas abordagens têm vários problemas em termos de escalabilidade, devido às suas características de centralização. Apresentando um melhor desempenho em termos de escalabilidade, as abordagens de gestão distribuída, por sua vez, são vantajosas nesse sentido, mas também apresentam uma série de desvantagens acerca do custo elevado de comunicação, autonomia, extensibilidade, exibilidade, robustez e cooperação entre os nós da rede. A cooperação entre os nós presentes na rede é normalmente a principal causa de sobrecarga na rede, uma vez que necessita de colectar, sincronizar e disseminar as informações de gestão para todos os nós nela presentes. Em ambientes dinâmicos, como é o caso das redes atuais e futuras, espera-se um crescimento exponencial no número de dispositivos, associado a um grau elevado de mobilidade dos mesmos na rede. Assim, o grau elevado de funções de automatiza ção da gestão da rede é uma exigência primordial, bem como o desenvolvimento de novos mecanismos e técnicas que permitam essa comunicação de forma optimizada e e ciente. Tendo em conta a necessidade de elevada cooperação entre os elementos da rede, as abordagens atuais para a gestão autonómica permitem que o administrador possa gerir grandes áreas de forma rápida e e ciente frente a problemas inesperados, visando diminuir a complexidade da rede e o uxo de informações de controlo nela gerados. Nas gestões autonómicas a delegação de operações da rede é suportada por um plano auto-organizado e não dependente de servidores centralizados ou externos. Com base nos tipos de gestão e desa os acima apresentados, esta Tese tem como principal objetivo propor e desenvolver um conjunto de mecanismos necessários para a criação de uma infra-estrutura de comunicação entre nós, na tentativa de satisfazer as exigências da gestão auton ómica e distribuída apresentadas pelas redes de futura geração. Nesse sentido, mecanismos especí cos incluindo inicialização e descoberta dos elementos da rede, troca de informação de gestão, (re) organização da rede e disseminação de dados foram elaborados e explorados em diversas condições e eventos, tais como: falhas de ligação, diferentes cargas de tráfego e exigências de rede. Para além disso, os mecanismos desenvolvidos são leves e portáveis, ou seja, podem operar em diferentes arquitecturas de hardware e contemplam todos os requisitos necessários para manter a base de comunicação e ciente entre os elementos da rede. Os resultados obtidos através de simulações e experiências reais comprovam que os mecanismos propostos apresentam um tempo de convergência menor para descoberta e troca de informação, um menor impacto na sobrecarga da rede, disseminação mais rápida da informação de gestão, aumento da estabilidade e a qualidade das ligações entre os nós e entrega e ciente de informações de dados em comparação com os mecanismos base analisados. Finalmente, todos os mecanismos desenvolvidos que fazem parte da infrastrutura de comunicação proposta foram concebidos e desenvolvidos para operar em cenários completamente descentralizados.
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Celik, Guner Dincer. "Distributed MAC protocol for networks with multipacket reception capability and spatially distributed nodes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40523.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 123-127).
The physical layer of future wireless networks will be based on novel radio technologies such as Ultra-Wideband (UWB) and Multiple-Input Multiple-Output (MIMO). One of the important capabilities of such technologies is the ability to capture a few packets simultaneously. This capability has the potential to improve the performance of the MAC layer. However, we show that in networks with spatially distributed nodes, reusing MAC protocols originally designed for narrow-band systems (e.g., CSMA/CA) is inefficient. It is well known that when networks with spatially distributed nodes operate with such MAC protocols, the channel may be captured by nodes that are near the destination. We show that when the physical layer enables multi-packet reception, the negative implications of reusing the legacy protocols include not only such unfairness but also a significant throughput reduction. We present a number of simple alternative backoff mechanisms that attempt to overcome the throughput reduction phenomenon. We evaluate the performance of these mechanisms via exact analysis, approximations, and simulation, thereby demonstrating that they usually outperform the legacy backoff mechanisms. We then discuss the implications of the results on developing realistic MAC protocols for networks with a multi-packet reception capability and in particular for UWB networks.
by Guner Dincer Celik.
S.M.
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Muralidharan, Gautam. "On the distributed revocation of nodes in sensor networks." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/164.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Brasileiro, Francisco Vilar. "Constructing fail-controlled nodes for distributed systems : a software approach." Thesis, University of Newcastle Upon Tyne, 1995. http://hdl.handle.net/10443/1971.
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Designing and implementing distributed systems which continue to provide specified services in the presence of processing site and communication failures is a difficult task. To facilitate their development, distributed systems have been built assuming that their underlying hardware components are Jail-controlled, i.e. present a well defined failure mode. However, if conventional hardware cannot provide the assumed failure mode, there is a need to build processing sites or nodes, and communication infra-structure that present the fail-controlled behaviour assumed. Coupling a number of redundant processors within a replicated node is a well known way of constructing fail-controlled nodes. Computation is replicated and executed simultaneously at each processor, and by employing suitable validation techniques to the outputs generated by processors (e.g. majority voting, comparison), outputs from faulty processors can be prevented from appearing at the application level. One way of constructing replicated nodes is by introducing hardwired mechanisms to couple replicated processors with specialised validation hardware circuits. Processors are tightly synchronised at the clock cycle level, and have their outputs validated by a reliable validation hardware. Another approach is to use software mechanisms to perform synchronisation of processors and validation of the outputs. The main advantage of hardware based nodes is the minimum performance overhead incurred. However, the introduction of special circuits may increase the complexity of the design tremendously. Further, every new microprocessor architecture requires considerable redesign overhead. Software based nodes do not present these problems, on the other hand, they introduce much bigger performance overheads to the system. In this thesis we investigate alternative ways of constructing efficient fail-controlled, software based replicated nodes. In particular, we present much more efficient order protocols, which are necessary for the implementation of these nodes. Our protocols, unlike others published to date, do not require processors' physical clocks to be explicitly synchronised. The main contribution of this thesis is the precise definition of the semantics of a software based Jail-silent node, along with its efficient design, implementation and performance evaluation.
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Davis, Jesse, Ron Kyker, and Nina Berry. "DESCRIPTION AND ANALYSIS OF A FLEXIBLE HARDWARE ARCHITECTURE FOR EVENT-DRIVEN DISTRIBUTED SENSOR NETWORK NODES." International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/605356.
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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaA particular engineering aspect of distributed sensor networks that has not received adequate attention is the system level hardware architecture of the individual nodes of the network. A novel hardware architecture based on an idea of task specific modular computing is proposed to provide for both the high flexibility and low power consumption required for distributed sensing solutions. The power consumption of the architecture is mathematically analyzed against a traditional approach, and guidelines are developed for application scenarios that would benefit from using this new design.
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Baleshan, Tharunie. "Analysis of distributed beamforming in cooperative communications network with phase shifter based smart antenna nodes." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84539/1/Tharunie_Baleshan_Thesis.pdf.
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This research study investigates the application of phase shifter-based smart antenna system in distributed beamforming. It examines the way to optimise the transmit power by jointly maximising the directivity of the array antennas and the weight vector for distributed beamforming. This research study concludes that maximising directivity can lead to better transmit power minimisation compared to maximising field intensity. This study also concludes that signal to noise power ratio maximisation subject to a power constraint and power minimisation subject to a signal to noise power ratio constraint yield the same results.
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Mercado, Albert. "Exploring data sharing between geographically distributed mobile and fixed nodes supporting Extended Maritime Interdiction Operations (EMIO)." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://bosun.nps.edu/uhtbin/hyperion-image.exe/08Jun%5FMercado.pdf.
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Thesis (M.S. in Information Systems and Operations)--Naval Postgraduate School, June 2008.Thesis Advisor(s): Bordetsky, Alex. "June 2008." Description based on title screen as viewed on August 26, 2008. Includes bibliographical references (p. 103-106). Also available in print.
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Engel, Andreas [Verfasser], Andreas [Akademischer Betreuer] Koch, and Christian [Akademischer Betreuer] Hochberger. "A Heterogeneous System Architecture for Low-Power Wireless Sensor Nodes in Compute-Intensive Distributed Applications / Andreas Engel ; Andreas Koch, Christian Hochberger." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1120585090/34.
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Wertlen, Ronald. "A P2P middleware design for digital access nodes in marginalised rural areas." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/254.
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This thesis addresses software design within the field of Information and Communications Technology for Development (ICTD). Specifically, it makes a case for the design and development of software which is custom-made for the context of marginalised rural areas (MRAs). One of the main aims of any ICTD project is sustainability and such sustainability is particularly difficult in MRAs because of the high costs of projects located there. Most literature on ICTD projects focuses on other factors, such as management, regulations, social and community issues when discussing this issue. Technical matters are often down-played or ignored entirely. This thesis argues that MRAs exhibit unique technical characteristics and that by understanding these characteristics, one can possibly design more cost-effective software. One specific characteristic is described and addressed in this thesis – a characteristic we describe here for the first time and call a network island. Further analysis of the literature generates a picture of a distributed network of access nodes (DANs) within such network islands, which are connected by high speed networks and are able to share resources and stimulate usage of technology by offering a wide range of services. This thesis attempts to design a fitting middleware platform for such a context, which would achieve the following aims: i) allow software developers to create solutions for the context more efficiently (correctly, rapidly); ii) stimulate product managers and business owners to create innovative software products more easily (cost-effectively). A given in the context of this thesis is that the software should use free/libre open source software (FLOSS) – good arguments do also exist for the use of FLOSS. A review of useful FLOSS frameworks is undertaken and several of these are examined in an applied part of the thesis, to see how useful they may be. They form the basis for a walking skeleton implementation of the proposed middleware. The Spring framework is the basis for experiments, along with Spring-Webservices, JMX and PHP 5’s web service capabilities. This thesis builds on three years of work at the Siyakhula Living Lab (SLL), an experimental testbed in a MRA in the Mbashe district of the Eastern Cape of South Africa. Several existing products are deployed at the SLL in the fields of eCommerce, eGovernment and eLearning. Requirements specifications are engineered from a variety of sources, including interviews, mailing lists, the author’s experience as a supervisor at the SLL, and a review of the existing SLL products. Future products are also investigated, as the thesis considers current trends in ICTD. Use cases are also derived and listed. Most of the use cases are concerned with management functions of DANs that can be automated, so that operators of DANs can focus on their core business and not on technology. Using the UML Components methodology, the thesis then proceeds to design a middleware component architecture that is derived from the requirements specification. The process proceeds step-by-step, so that the reader can follow how business rules, operations and interfaces are derived from the use cases. Ultimately, the business rules, interfaces and operations are related to business logic, system interfaces and operations that are situated in specific components. The components in turn are derived from the business information model, that is derived from the business concepts that were initially used to describe the context for the requirements engineering. In this way, a logical method for software design is applied to the problem domain to methodically derive a software design for a middleware solution. The thesis tests the design by considering possible weaknesses in the design. The network aspect is tested by interpolating from formal assumptions about the nature of the context. The data access layer is also identified as a possible bottleneck. We suggest the use of fast indexing methods instead of relational databases to maintain flexibility and efficiency of the data layer. Lessons learned from the exercise are discussed, within the context of the author’s experience in software development teams, as well as in ICTD projects. This synthesis of information leads to warnings about the psychology of middleware development. We note that the ICTD domain is a particularly difficult one with regards to software development as business requirements are not usually clearly formulated and developers do not have the requisite domain knowledge. In conclusion, the core arguments of the thesis are recounted in a bullet form, to lay bare the reasoning behind this work. Novel aspects of the work are also highlighted. They include the description of a network island, and aspects of the DAN middleware requirements engineering and design. Future steps for work based on this thesis are mapped out and open problems relating to this research are touched upon.
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Shen, Guowei [Verfasser], Reiner [Akademischer Betreuer] Thomä, Jörn [Gutachter] Thielecke, and Günther [Gutachter] Schäfer. "Localization of Active Nodes within Distributed UWB Sensor Networks in Multipath Environments / Guowei Shen ; Gutachter: Jörn Thielecke, Günther Schäfer ; Betreuer: Reiner Thomä." Ilmenau : TU Ilmenau, 2012. http://d-nb.info/1178185621/34.
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Hedges, Mitchell Lawrence. "An investigation into the use of intuitive control interfaces and distributed processing for enhanced three dimensional sound localization." Thesis, Rhodes University, 2016. http://hdl.handle.net/10962/d1020615.
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This thesis investigates the feasibility of using gestures as a means of control for localizing three dimensional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. the successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.
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Khan, Muhammad Abbas. "Detection of collapses and communicating with inaccessible areas in underground coal mines using WSN." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1782.
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Wireless sensor networks (WSN) are used in underground mines to monitor concentration of gases, temperature, and humidity. A WSN deployed in underground mines can also be used for localisation of miners and for detecting collapses. Underground coal mines consist of long and narrow tunnels, several hundred metres beneath the surface of earth. These tunnels can be several kilometres long, with the width and height of these tunnels being no more than a few metres. A WSN in underground coal mine is an example of a chain type wireless sensor network (CWSN). CWSNs are special types of WSNs in which sensor nodes are placed along an elongated geographical area with the nodes forming a chain topology. In CWSNs, their shape dictates network design. Unlike other large scale WSN, there is only one path for data transfer in CWSNs. Hence the probability of network getting broken in disjoint sections, due to node failures, is much higher in CWSNs compared to other large scale WSNs. Disjoint sections are two sections of the same network which are out of the communication range of each other. When the network is broken into two or more disjoint sections, the sink node loses connectivity with parts of the network and hence some areas are left unmonitored despite having functional sensor nodes.
In the first contribution chapter of this thesis, we design a distributed connectivity restoration algorithm for generic chain-type wireless sensor networks. We usemovable relay nodes to restore connectivity in the network. Our algorithm strivesto move a minimum number of relay nodes while only requiring local knowledge ofthe network. In the second contribution chapter, we consider the scenario of collapses occurring in underground coal mines. We design an algorithm for detecting collapses in chapter four. A collapse may leave parts of the mine inaccessible and unmonitored. A collapse will also break WSN into two or more disjoint sections which are physically separated by the collapse consisting of soil and rock. We investigate the propagation characteristics of EM waves through soil and rock. We determine the factors on which communication range of EM waves through soil depends on. We propose special movable relay nodes which use low frequency and high power transmitters to communicate through a collapsed area of the mine, restoring connectivity in the WSN. We design an algorithm to restore connectivity through collapsed areas of the underground mine tunnels using these special movable relay nodes. Communicating with inaccessible area of the mine will help locate miners which may be trapped in that section and will enable the network to monitor the inaccessible area of the mine.
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Azmy, Noran. "A Machine-Checked Proof of Correctness of Pastry." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0277/document.
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Les réseaux pair-à-pair (P2P) constituent un modèle de plus en plus populaire pour la programmation d’applications Internet car ils favorisent la décentralisation, le passage à l’échelle, la tolérance aux pannes et l’auto-organisation. à la différence du modèle traditionnel client-serveur, un réseau P2P est un système réparti décentralisé dans lequel tous les nœuds interagissent directement entre eux et jouent à la fois les rôles de fournisseur et d’utilisateur de services et de ressources. Une table de hachage distribuée (DHT) est réalisée par un réseauP2P et offre les mêmes services qu’une table de hachage classique, hormis le fait que les différents couples (clef, valeur) sont stockés dans différents nœuds du réseau. La fonction principale d’une DHT est la recherche d’une valeur associée à une clef donnée. Parmi les protocoles réalisant une DHT on peut nommer Chord, Pastry, Kademlia et Tapestry. Ces protocoles promettent de garantir certaines propriétés de correction et de performance ; or, les tentatives de démontrer formellement de telles propriétés se heurtent invariablement à des cas limites dans lesquels certaines propriétés sont violées. Tian-xiang Lu a ainsi décrit des problèmes de correction dans des versions publiées de Pastry. Il a conçu un modèle, appelé LuPastry, pour lequel il a fourni une preuve partielle, mécanisée dans l’assistant à la preuve TLA+ Proof System, démontrant que les messages de recherche de clef sont acheminés au bon nœud du réseau dans le cas sans départ de nœuds. En analysant la preuve de Lu j’ai découvert qu’elle contenait beaucoup d’hypothèses pour lesquelles aucune preuve n’avait été fournie, et j’ai pu trouver des contre-exemples à plusieurs de ces hypothèses. La présente thèse apporte trois contributions. Premièrement, je présente LuPastry+, une spécification TLA+ revue de LuPastry. Au-delà des corrections nécessaires d’erreurs, LuPastry+ améliore LuPastry en introduisant de nouveaux opérateurs et définitions, conduisant à une spécification plus modulaire et isolant la complexité de raisonnement à des parties circonscrites de la preuve, contribuant ainsi à automatiser davantage la preuve. Deuxièmement, je présente une preuve TLA+ complète de l’acheminement correct dans LuPastry+. Enfin, je démontre que l’étape finale du processus d’intégration de nœuds dans LuPastry (et LuPastry+) n’est pas nécessaire pour garantir la cohérence du protocole. Concrètement, j’exhibe une nouvelle spécification avec un processus simplifié d’intégration de nœuds, que j’appelle Simplified LuPastry+, et je démontre qu’elle garantit le bon acheminement de messages de recherche de clefs. La preuve de correction pour Simplified LuPastry+ est obtenue en réutilisant la preuve pour LuPastry+, et ceci représente un bon succès pour la réutilisation de preuves, en particulier considérant la taille de ces preuves. Chacune des deux preuves requiert plus de 30000 étapes interactives ; à ma connaissance, ces preuves constituent les preuves les plus longues écrites dans le langage TLA+ à ce jour, et les seuls exemples d’application de preuves mécanisées de théorèmes pour la vérification de protocoles DHTA distributed hash table (DHT) is a peer-to-peer network that offers the function of a classic hash table, but where different key-value pairs are stored at different nodes on the network. Like a classic hash table, the main function provided by a DHT is key lookup, which retrieves the value stored at a given key. Examples of DHT protocols include Chord, Pastry, Kademlia and Tapestry. Such DHT protocols certain correctness and performance guarantees, but formal verification typically discovers border cases that violate those guarantees. In his PhD thesis, Tianxiang Lu reported correctness problems in published versions of Pastry and developed a model called {\LP}, for which he provided a partial proof of correct delivery of lookup messages assuming no node failure, mechanized in the {\TLA} Proof System. In analyzing Lu's proof, I discovered that it contained unproven assumptions, and found counterexamples to several of these assumptions. The contribution of this thesis is threefold. First, I present {\LPP}, a revised {\TLA} specification of {\LP}. Aside from needed bug fixes, {\LPP} contains new definitions that make the specification more modular and significantly improve proof automation. Second, I present a complete {\TLA} proof of correct delivery for {\LPP}. Third, I prove that the final step of the node join process of {\LP}/{\LPP} is not necessary to achieve consistency. In particular, I develop a new specification with a simpler node join process, which I denote by {\SLP}, and prove correct delivery of lookup messages for this new specification. The proof of correctness of {\SLP} is written by reusing the proof for {\LPP}, which represents a success story in proof reuse, especially for proofs of this size. Each of the two proofs amounts to over 32,000 proof steps; to my knowledge, they are currently the largest proofs written in the {\TLA} language, and---together with Lu's proof---the only examples of applying full theorem proving for the verification of DHT protocols
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Johannsen, Fabian, and Mattias Hellsing. "Hadoop Read Performance During Datanode Crashes." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-130466.
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This bachelor thesis evaluates the impact of datanode crashes on the performance of the read operations of a Hadoop Distributed File System, HDFS. The goal is to better understand how datanode crashes, as well as how certain parameters, affect the performance of the read operation by looking at the execution time of the get command. The parameters used are the number of crashed nodes, block size and file size. By setting up a Linux test environment with ten virtual machines and Hadoop installed on them and running tests on it, data has been collected in order to answer these questions. From this data the average execution time and standard deviation of the get command was calculated. The network activity during the tests was also measured. The results showed that neither the number of crashed nodes nor block size had any significant effect on the execution time. It also demonstrated that the execution time of the get command was not directly proportional to the size of the fetched file. The execution time was up to 4.5 times as long when the file size was four times as large. A four times larger file did sometimes result in more than a four times as long execution time. Although, the consequences of a datanode crash while fetching a small file appear to be much greater than with a large file. The average execution time increased by up to 36% when a large file was fetched but it increased by as much as 85% when fetching a small file.
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Craveiro, Gisele da Silva. "Um ambiente de execução para suporte à programação paralela com variáveis compartilhadas em sistemas distribuídos heterogêneos." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-04062004-160551/.
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O avanço na tecnologia de hardware está permitindo que máquinas SMP de 2 a 8 processadores estejam disponíveis a um custo cada vez menor, possibilitando que a incorporação de tais máquinas em aglomerados de PC's ou até mesmo a composição de um aglomerado de SMP's sejam alternativas cada vez mais viáveis para computação de alto desempenho. O grande desafio é extrair o potencial que tal conjunto de máquinas oferece. Uma alternativa é usar um paradigma híbrido de programação para aproveitar a arquitetura de memória compartilhada através de multihreadeing e utilizar o modelo de troca de mensagens para comunicação entre os nós. Contudo, essa estratégia impõe uma tarefa árdua e pouco produtiva para o programador da aplicação. Este trabalho apresenta o sistema CPAR- Cluster que oferece uma abstração de memória compartilhada no topo de um aglomerado formado por nós mono e multiprocessadores. O sistema é implementado no nível de biblioteca e não faz uso de recursos especiais tais como hardware especializado ou alteração na camada de sistema operacional. Serão apresentados os modelos, estratégias, questões de implementação e os resultados obtidos através de testes realizados com a ferramenta e que apresentaram comportamento esperado.The advance in hardware technologies is making small configuration SMP machines (from 2 to 8 processors) available at a low cost. For this reason, the inclusion of an SMP node into a cluster of PCs or even clusters of SMPs are becoming viable alternatives for high performance computing. The challenge is the exploitation of the computational resources that these platforms provide. A Hybrid programming paradigm which uses shared memory architecture through multihreading and also message passing model for inter node communication is an alternative. However, programming in such paradigm is very hard. This thesis presents CPAR- Cluster, a runtime system, that provides shared memory abstraction on top of a cluster composed by mono and multiprocessor nodes. Its implementation is at the library level and doesn't require special resources such as particular hardware or operating system moditfications. Models, strategies, implementation aspects and results will be presented.
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Latif, L. "Node selection in distributed overlays." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1389944/.
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With the proliferation of latency aware services such as live video streaming, Internetbased financial trading and the popularity of distributed overlays such as BitTorrent there is a growing need for latency-aware distributed overlays. To make such overlays viable, efficient resource discovery services are needed. Anycast is a routing protocol that sends packets to nodes that are a member of a particular group, with the work presented the Anycast protocol in the distributed overlay domain. Structured and unstructured distributed networks have become a popular way to disseminate data without the need for a fixed infrastructure, however there is a need to provide quality of service (QoS). To meet the demands of applications, an overlay needs to maintain accurate Anycast group membership data, locality information and have minimal protocol overhead. Three protocols are proposed to meet these goals. The Distributed Overlay Anycast Table (DOAT) brings the notion of locality to a structured overlay, while introducing Bloom filters as an efficient data structure to present an overlay that can accurately return a node that is participating in a particular group. The Gossip Overlay Anycast Table (GOAT) is a scalable location-aware unstructured overlay that can provide the probabilistic Anycast routing. Through the use of an efficient discovery protocol and the use of Bloom filters, GOAT is able to provide the advantages of a structured overlay, while mitigating the performance issues typically found in unstructured overlays. The N-casting overlay is an unstructured overlay with the ability to send queries to multiple members of an group, uses a hierarchical decomposition of the Internet and an elegant data structure that offers predictable compression of overlay membership. N-casting shows that unstructured overlays can be scalable and sustain high performance in environments that exhibit realistic membership churn. DOAT, GOAT and N-casting present viable services that implemented at the application layer provide location aware node discovery in QoS-enabled applications.
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Schröter, W. "„Distributed Learning“ unter Lotus Notes - ein Erfahrungsbericht." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-210853.
Full textAbstract:
Zusammenfassung:
"Der wachsende Bildungsbedarf zwingt auch mittelständische Unternehmen, sich mit virtuellen Lerngemeinschaften und betreutem, verteiltem Lernen zu beschäftigen. Der Beitrag beschreibt Ansätze, die in einem Beratungsunternehmen mit LearningSpace entwickelt wurden. Ausgehend von didaktischen Grundlagen für neue Lehr- und Lernumgebungen werden die Installation und Realisation und insbesondere die Erfahrungen der ersten Pilotprojekte diskutiert. Beobachtungen und Erfahrungen mit der Technik, mit den Lernenden und den Lehrenden, ihrer Kommunikation und Kooperation, bilden die Grundlage für Veränderungen in weiteren Projekten. Konsequenzen ergeben sich insbesondere für die Betreuung der Lernenden und die Einbettung in ein Gesamtkonzept."
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Schröter, W. "„Distributed Learning“ unter Lotus Notes - ein Erfahrungsbericht." Josef Eul Verlag GmbH, 1999. https://tud.qucosa.de/id/qucosa%3A29860.
Full textAbstract:
Zusammenfassung:
'Der wachsende Bildungsbedarf zwingt auch mittelständische Unternehmen, sich mit virtuellen Lerngemeinschaften und betreutem, verteiltem Lernen zu beschäftigen. Der Beitrag beschreibt Ansätze, die in einem Beratungsunternehmen mit LearningSpace entwickelt wurden. Ausgehend von didaktischen Grundlagen für neue Lehr- und Lernumgebungen werden die Installation und Realisation und insbesondere die Erfahrungen der ersten Pilotprojekte diskutiert. Beobachtungen und Erfahrungen mit der Technik, mit den Lernenden und den Lehrenden, ihrer Kommunikation und Kooperation, bilden die Grundlage für Veränderungen in weiteren Projekten. Konsequenzen ergeben sich insbesondere für die Betreuung der Lernenden und die Einbettung in ein Gesamtkonzept.
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Zinkhon, David C. "Undersea node localization using node-to-node acoustic ranges in a distributed Seaweb network." Thesis, Monterey, Calif. : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/March/09Mar%5FZinkhon.pdf.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, March 2009.Thesis Advisor(s): Rice, Joseph A. "March 2009." Description based on title screen as viewed on April 24, 2009. Author(s) subject terms: Underwater acoustics, Seaweb, Localization, Difference linearization. Includes bibliographical references (p. 97-98). Also available in print.
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Long, J. A. "Implementing a heterogeneous relational database node." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355094.
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Megahed, Mohamed Helmy Mostafa. "SurvSec Security Architecture for Reliable Surveillance WSN Recovery from Base Station Failure." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31154.
Full textAbstract:
Surveillance wireless sensor networks (WSNs) are highly vulnerable to the failure of the base station (BS) because attackers can easily render the network useless for relatively long periods of time by only destroying the BS. The time and effort needed to destroy the BS is much less than that needed to destroy the numerous sensing nodes.
Previous works have tackled BS failure by deploying a mobile BS or by using multiple BSs, which requires extra cost. Moreover, despite using the best electronic countermeasures, intrusion tolerance systems and anti-traffic analysis strategies to protect the BSs, an adversary can still destroy them. The new BS cannot trust the deployed sensor nodes. Also, previous works lack both the procedures to ensure network reliability and security during BS failure such as storing then sending reports concerning security threats against nodes to the new BS and the procedures to verify the trustworthiness of the deployed sensing nodes. Otherwise, a new WSN must be re-deployed which involves a high cost and requires time for the deployment and setup of the new WSN. In this thesis, we address the problem of reliable recovery from a BS failure by proposing a new security architecture called Surveillance Security (SurvSec).
SurvSec continuously monitors the network for security threats and stores data related to node security, detects and authenticates the new BS, and recovers the stored data at the new BS. SurvSec includes encryption for security-related information using an efficient dynamic secret sharing algorithm, where previous work has high computations for dynamic secret sharing. SurvSec includes compromised nodes detection protocol against collaborative work of attackers working at the same time where previous works have been inefficient against collaborative work of attackers working at the same time.
SurvSec includes a key management scheme for homogenous WSN, where previous works assume heterogeneous WSN using High-end Sensor Nodes (HSN) which are the best target for the attackers. SurvSec includes efficient encryption architecture against quantum computers with a low time delay for encryption and decryption, where previous works have had high time delay to encrypt and decrypt large data size, where AES-256 has 14 rounds and high delay. SurvSec consists of five components, which are:
1. A Hierarchical Data Storage and Data Recovery System.
2. Security for the Stored Data using a new dynamic secret sharing algorithm.
3. A Compromised-Nodes Detection Algorithm at the first stage.
4. A Hybrid and Dynamic Key Management scheme for homogenous network.
5. Powerful Encryption Architecture for post-quantum computers with low time delay.
In this thesis, we introduce six new contributions which are the followings:
1. The development of the new security architecture called Surveillance Security (SurvSec) based on distributed Security Managers (SMs) to enable distributed network security and distributed secure storage.
2. The design of a new dynamic secret sharing algorithm to secure the stored data by using distributed users tables.
3. A new algorithm to detect compromised nodes at the first stage, when a group of attackers capture many legitimate nodes after the base station destruction. This algorithm is designed to be resistant against a group of attackers working at the same time to compromise many legitimate nodes during the base station failure.
4. A hybrid and dynamic key management scheme for homogenous network which is called certificates shared verification key management.
5. A new encryption architecture which is called the spread spectrum encryption architecture SSEA to resist quantum-computers attacks.
6. Hardware implementation of reliable network recovery from BS failure.
The description of the new security architecture SurvSec components is done followed by a simulation and analytical study of the proposed solutions to show its performance.
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Liljenberg, Lars. "System Testing of Distributed Systems Using Node-Based Framework." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260691.
Full textAbstract:
Existing methods for testing distributed systems are discussed and compared. A prototype of a new tool with support for executing distributed tests is developed and discussed. The new tool supports writing tests consisting of multiple nodes which can be coordinated from a master node through the use of remote procedure calls. A detailed description of the design and functionality of the tool is given, as well as an overview of how the tool itself was tested. In addition, a use case is presented where the tool is used for testing a conceptual distributed system, and the tool is found to work well for its intended purpose.
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Sueverachai, Thanakorn. "Design and Implementation ofa Network Search Node." Thesis, KTH, Kommunikationsnät, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141424.
Full textAbstract:
Networked systems, such as cloud infrastructures, are growing in size and complexity.They hold and generate a vast amount of configuration and operational data, whichis maintained in various locations and formats, and changes at various time scales.A wide range of protocols and technologies is used to access this data for networkmanagement tasks. A concept called ‘network search’ is introduced to make all thisdata available in real-time through a search platform with a uniform interface, whichenables location-independent access through search queries. Network search requires a network of search nodes, where the nodes have identicalcapabilities and work cooperatively to process search queries in a peer-to-peer fashion.A search node should indicate good performance results in terms of low query responsetimes, high throughputs, and low overhead costs and should scale to large networkedsystems with at least hundred thousands nodes. This thesis contributes in several aspects towards the design and implementation of anetwork search node. We designed a search node that includes three major components,namely, a real-time data sensing component, a real-time database, and a distributedquery-processing component. The design takes indexing of search terms and concurrencyof query processing into consideration, which accounts for fast response timesand high throughput of search queries. We implemented a network search node as asoftware package that runs on a server that provides a cloud service, and we evaluatedits performance on a cloud testbed of nine servers. The performance measurementssuggest that a network search system based on our design can process queries at lowquery latencies for a high query load, while maintaining a low overhead of computationalresources.
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Derasevic, Sinisa. "Node fault tolerance for distributed embedded systems based on FTT-Ethernet." Doctoral thesis, Universitat de les Illes Balears, 2018. http://hdl.handle.net/10803/666276.
Full textAbstract:
[eng] When Distributed Embedded Systems (DESs) operate in evolving environments,
changing requirements might be imposed on the system, and thus the system
needs the ability to adapt to them. Furthermore, when such systems are
employed for real-time (RT) critical applications, both support for satisfying stringent RT guarantees and attaining a high level of reliability must be provided.
The Flexible Time-Triggered (FTT) communication paradigm provides support
for changing real-time traffic requirements in adaptive RT DESs, i.e., it provides
RT flexibility. The different implementations of FTT on Ethernet have recently
added to FTT advantages of Ethernet such as high bandwidth, low cost and, since
Ethernet is the de facto Link Layer standard of many communication systems,
also an easier potential integration.
A specific FTT implementation on Ethernet, called Flexible Time-Triggered
Ethernet Star (FTTRS), has been recently proposed to add mechanisms to
tolerate faults in the channel as a means to increase the reliability of the final
system. However, it is known that to reach a very high level of system reliability it
is crucial to also tolerate faults in the computation nodes. This is so because the
computation nodes are usually the most complex components of a DES and,
hence, they are less reliable than most of the components that constitute the
channel, e.g. the links.
This thesis proposes a node replication architecture and appropriate node faulttolerance
(FT) mechanisms so as to attain a high level of reliability for critical RT
DES. The proposed architecture and FT mechanisms are based on an active node
replication strategy with distributed majority voting. The mechanisms are
designed on top of FTTRS in order to take advantage of the features that the FTT
paradigm and the FTTRS communication subsystem already provide in terms of
channel RT flexibility and channel fault tolerance.
We start by introducing the concepts, terminology and methodology used to
specify, design and test a fault-tolerant system. Special attention has been paid to
describing the specific fault-tolerance techniques used in this dissertation. Also,
we present the foundations on top of which we develop our node FT mechanisms.
In particular we present the FTT communication paradigm and the details of the
FTTRS itself.
Then, we describe the main contributions of this dissertation. We start by a
general description of the overall system. Then, we clarify what types of faults
(fault model) we address, and we thoroughly describe and classify all the
manners in which these faults may manifest (failure model). Afterwards we focus
on describing the proposed FT mechanisms based on both active node replication and FTTRS. Once this description is completed, we propose a realization of the
designed FT mechanisms for the specific case of control applications.
Moreover, in order to test and verify the correctness of our node replication
architecture and FT mechanisms, we present a simulation model as well as a real
prototype. We use these simulation model and real prototype to thoroughly inject
faults (in terms of all the manners in which faults can manifest according to the
failure model) and, then, we inspect if the mechanisms function as intended in
both of them. Finally, we build a dependability model to quantify the level of
reliability attainable by a DES relying on our node replication architecture and FT
mechanisms.
By means of the work described in the current dissertation we prove the
following thesis statement:
“It is possible to attain high levels of reliability of adaptive critical RT DES that
rely on a reliable and flexible RT communication subsystem based on an FTT
implementation on Ethernet by providing FT mechanisms for the nodes.”[spa] Los sistemas empotrados distribuidos son sistemas compuestos por un conjunto de nodos interconectados que trabajan para lograr un objetivo común y que forman parte de un sistema mecánico o eléctrico más grande. Los nodos suelen estar interconectados por medio de una red de comunicación. En cuanto a las redes de comunicación, en las últimas décadas Ethernet se ha convertido en una de las tecnologías más populares debido a sus muchas ventajas tales como simplicidad, anchos de banda siempre crecientes y bajo coste, entre otras. Cuando los sistemas empotrados distribuidos forman parte de sistemas más grandes que ejecutan aplicaciones críticas, a menudo existe la necesidad de proporcionar un soporte para requisitos de respuesta en tiempo real y para la consecución de una muy elevada fiabilidad. La tecnología original de Ethernet no proporciona ningún soporte de este tipo. Por lo tanto, en esta disertación usamos el recientemente propuesto subsistema de comunicación que recibe el nombre de Flexible Time-Triggered Replicated Star (FTTRS) como medio para interconectar los nodos de los sistemas empotrados distribuidos que ejecutan aplicaciones críticas. FTTRS toma la tecnología de red Ethernet como base y sobre ella proporciona mecanismos para soportar respuesta en tiempo real y elevada fiabilidad. La respuesta en tiempo real es proporcionada por el uso del paradigma de comunicación Flexible Time-Triggered (FTT) implementado sobre el protocolo Ethernet el cual, además de la provisión de garantías de tiempo real, también proporciona flexibilidad, en concreto, la capacidad de modificar el comportamiento de la red en tiempo de ejecución mientras se mantienen las garantías de tiempo real comprometidas. La elevada fiabilidad en FTTRS se logra mediante mecanismos que toleran los fallos que podrían afectar a la comunicación entre nodos. Sin embargo, proporcionar tolerancia a fallos únicamente al subsistema de comunicación no es suficiente para satisfacer los requisitos de fiabilidad más exigentes de las aplicaciones críticas. Para alcanzar altos niveles de fiabilidad, los fallos en los propios nodos del sistema empotrado distribuido también deben ser tratados. En consecuencia, hemos diseñado varios mecanismos de tolerancia a fallos para tratar los fallos que puedan afectar al correcto funcionamiento de los nodos. Estos mecanismos aprovechan las características del subsistema de comunicación FTTRS y del paradigma de comunicación FTT subyacente. Concluyendo, en esta tesis veremos cómo podemos, con la introducción de mecanismos específicos para tolerar los fallos de los nodos de un sistema empotrado distribuido basado en FTTRS, lograr muy elevados niveles de fiabilidad para el sistema en su conjunto. Además del diseño de los mecanismos de tolerancia a fallos de los nodos, también mostraremos cómo se puede evaluar la fiabilidad resultante y estableceremos cuál es el beneficio obtenido, comparando dicha fiabilidad con la de una versión no tolerante a fallos del mismo sistema.
[cat] Els sistemes encastats distribuïts són sistemes composts per un conjunt de nodes interconnectats que treballen per aconseguir un objectiu comú i que formen part d’un sistema mecànic o elèctric més gran. Els nodes solen estar interconnectats mitjançant una xarxa de comunicació. Quant a les xarxes de comunicació, en les últimes dècades Ethernet s’ha convertit en una de les tecnologies més populars a causa dels seus molts avantatges tals com a simplicitat, amples de banda sempre creixents i baix cost, entre d’altres. Quan els sistemes encastats distribuïts formen part de sistemes més grans que executen aplicacions crítiques, sovint existeix la necessitat de proporcionar un suport per a requisits de resposta en temps real i per a la consecució d’una molt elevada fiabilitat. La tecnologia original d’Ethernet no proporciona cap suport d’aquest tipus. Per tant, en aquesta dissertació usem el recentment proposat subsistema de comunicació que rep el nom de Flexible Time-Triggered Replicated Star (FTTRS) com a mitjà per interconnectar els nodes dels sistemes encastats distribuïts que executen aplicacions crítiques. FTTRS pren la tecnologia de xarxa Ethernet com a base i sobre ella proporciona mecanismes per suportar resposta en temps real i elevada fiabilitat. La resposta en temps real és proporcionada per l’ús del paradigma de comunicació Flexible Time-Triggered (FTT) implementat sobre el protocol Ethernet el qual, a més de la provisió de garanties de temps real, també proporciona flexibilitat, en concret, la capacitat de modificar el comportament de la xarxa en temps d’execució mentre es mantenen les garanties de temps real compromeses. L’elevada fiabilitat en FTTRS s’aconsegueix mitjançant mecanismes que toleren les fallades que podrien afectar a la comunicació entre nodes. En qualsevol cas, proporcionar tolerància a fallades únicament al subsistema de comunicació no és suficient per satisfer els requisits de fiabilitat més exigents de les aplicacions crítiques. Per aconseguir alts nivells de fiabilitat, les fallades en els propis nodes del sistema encastat distribuït també han de ser tractades. En conseqüència, hem dissenyat diversos mecanismes de tolerància a fallades per tractar les fallades que puguin afectar al correcte funcionament dels nodes. Aquests mecanismes aprofiten les característiques del subsistema de comunicació FTTRS i del paradigma de comunicació FTT subjacent. Concloent, en aquesta tesi veurem com podem, amb la introducció de mecanismes específics per tolerar les fallades dels nodes d’un sistema encastat distribuït basat en FTTRS, aconseguir molt elevats nivells de fiabilitat per al sistema en el seu conjunt. A més del disseny dels mecanismes de tolerància a fallades dels nodes, també mostrarem com es pot avaluar la fiabilitat resultant i establirem quin és el benefici obtingut, comparant aquesta fiabilitat amb la d’una versió no tolerant a fallades del mateix sistema.
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Hutcheon, Andrew David. "The virtual node approach to real-time, fault-tolerant distributed Ada." Thesis, University of York, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357115.
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SEETHARAMAN, SUMATHI. "SELF-ORGANIZED SCHEDULING OF NODE ACTIVITY IN LARGE-SCALE SENSOR NETWORKS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092939502.
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Baloch, Javed Ali. "Inter-node cooperation pivoting upon location for spatially distributed smart sensor networks." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536111.
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Gadde, Srimanth. "Graph Partitioning Algorithms for Minimizing Inter-node Communication on a Distributed System." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1376561814.
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Khanapure, Vishal. "Memory efficient distributed detection of node replication attacks in wireless sensor networks." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0025072.
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Aranha, Diego de Freitas 1982. "Serviço de nomes e roteamento para redes de anonimização de trafego." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276244.
Full textAbstract:
Orientador: Julio Cesar Lopez HernandezDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
Made available in DSpace on 2018-08-08T21:36:28Z (GMT). No. of bitstreams: 1 Aranha_DiegodeFreitas_M.pdf: 6440821 bytes, checksum: d67da255f787776d44a1b825e26c1a65 (MD5) Previous issue date: 2007
Resumo: Em diversos cenários, é desejável que não apenas o conteúdo de uma comunicação seja preservado, mas também a identidade dos seus participantes. Satisfazer esta propriedade requer mecanismos diferentes dos comumente utilizados para fornecer sigilo e autenticidade. Neste trabalho, a problemática da comunicação anônima na Internet é abordada a partir do projeto e implementação de componentes específicos para este fim. Em particular, são apresentados um componente para roteamento anônimo eficiente em sistemas peer-to-peer estruturados e um serviço de nomes para facilitar a publicação de serviços anonimizados. As principais contribuições deste trabalho são: (i) estudo de definições, métricas e técnicas relacionadas a anonimato computacional; (ii) estudo do paradigma de Criptografia de Chave Pública Sem Certificados; (iii) projeto de uma rede de anonimização completa, adequada tanto para comunicação genérica como para funcionalidade específica; (iv) estudo e projeto de esquemas de roteamento em ambientes anônimos; (v) projeto de um serviço de nomes que aplica técnicas criptográficas avançadas para fornecer suporte a serviços anonimizados; (vi) implementação em software dos conceitos apresentados
Abstract: In several scenarios, it¿s desirable to protect not only the content of a communication, but the identities of its participants. To satisfy this property, different techniques from those used to support confidentiality and authentication are commonly required. In this work, the problem of anonymous communication on the Internet is explored through the design and implementation of specific components with this function. In particular, a name service and a routing component for anonymous environments are presented. The main contributions of this work are: (i) the study of definitions, metrics and techniques related to computational anonymity; (ii) the study of Certificateless Public Key Cryptography, a new model of public key cryptography; (iii) the design of a complete anonymization network, suitable for both generic communication and dedicated functionality; (iv) the study and design of routing schemes for anonymous communication; (v) the design of a name service to support location-hidden services in the anonymous network; (vi) the implementation of the concepts presented.
Mestrado
Criptografia e Segurança Computacional
Mestre em Ciência da Computação
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Jimenez, Raúl. "Kademlia on the Open Internet : How to Achieve Sub-Second Lookups in a Multimillion-Node DHT Overlay." Licentiate thesis, KTH, Telekommunikationssystem, TSLab, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-46469.
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Distributed hash tables (DHTs) have gained much attention from the research community in the last years. Formal analysis and evaluations on simulators and small-scale deployments have shown good scalability and performance. In stark contrast, performance measurements in large-scale DHT overlays on the Internet have yielded disappointing results, with lookup latencies measured in seconds. Others have attempted to improve lookup performance with very limited success, their lowest median lookup latency at over one second and a long tail of high-latency lookups. In this thesis, the goal is to to enable large-scale DHT-based latency-sensitive applications on the Internet. In particular, we improve lookup latency in Mainline DHT, the largest DHT overlay on the open Internet, to identify and address practical issues on an existing system. Our approach is implementing and measuring backward-compatible modifications to facilitate their incremental adoption into Mainline DHT (and possibly other Kademlia-based overlays). Thus, enabling our research to have impact on a real-world system. Our results close the performance gap between small- and large-scale DHT overlays. With a median lookup latency below 200 ms and a 99\superscript{th} percentile of just above 500 ms, our median lookup latency is one order of magnitude lower than the best performing measurement reported in the literature. Moreover, our results do not show a long tail of high-latency lookups, unlike previous reports. We have achieved these results by studying how connectivity artifacts on the underlying network ---probably caused by firewalls and NAT devices on the Internet--- affect the DHT overlay. Our measurements of the connectivity of more than 3 million nodes reveal that connectivity artifacts are widespread and can severely degrade lookup performance. Scalability and locality-awareness have also been explored in this thesis, where different mechanisms have been proposed. Some of the mechanisms are planned to be integrated into Mainline DHT in future work.QC 20111118
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Radovic, Zoran. "Software Techniques for Distributed Shared Memory." Doctoral thesis, Uppsala University, Department of Information Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6058.
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In large multiprocessors, the access to shared memory is often nonuniform, and may vary as much as ten times for some distributed shared-memory architectures (DSMs). This dissertation identifies another important nonuniform property of DSM systems: nonuniform communication architecture, NUCA. High-end hardware-coherent machines built from large nodes, or from chip multiprocessors, are typical NUCA systems, since they have a lower penalty for reading recently written data from a neighbor's cache than from a remote cache. This dissertation identifies node affinity as an important property for scalable general-purpose locks. Several software-based hierarchical lock implementations exploiting NUCAs are presented and evaluated. NUCA-aware locks are shown to be almost twice as efficient for contended critical sections compared to traditional lock implementations.
The shared-memory “illusion”' provided by some large DSM systems may be implemented using either hardware, software or a combination thereof. A software-based implementation can enable cheap cluster hardware to be used, but typically suffers from poor and unpredictable performance characteristics.
This dissertation advocates a new software-hardware trade-off design point based on a new combination of techniques. The two low-level techniques, fine-grain deterministic coherence and synchronous protocol execution, as well as profile-guided protocol flexibility, are evaluated in isolation as well as in a combined setting using all-software implementations. Finally, a minimum of hardware trap support is suggested to further improve the performance of coherence protocols across cluster nodes. It is shown that all these techniques combined could result in a fairly stable performance on par with hardware-based coherence.
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Abdlwafa, Alan, and Henrik Edman. "Distributed Graph Mining : A study of performance advantages in distributed data mining paradigms when processing graphs using PageRank on a single node cluster." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166449.
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Distributed data mining is a relatively new area within computer science that is steadily growing, emerging from the demands of being able to gather and process various distributed data by utilising clusters. This report presents the properties of graph structured data and what paradigms to use for efficiently processing the data type, based on comprehensive theoretical studies applied on practical tests performed on a single node cluster. The results in the study showcase the various performance aspects of processing graph data, using different open source paradigm frameworks and amount of shards used on input. A conclusion to be drawn from this study is that there are no real performance advantages to using distributed data mining paradigms specifically developed for graph data on single machines.
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Rochholz, Timothy W. "Wave-Powered Unmanned Surface Vehicle as a Station-Keeping Gateway Node for Undersea Distributed Networks." Thesis, Monterey, California. Naval Postgraduate School, 2012. http://hdl.handle.net/10945/17448.
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Approved for public release; distribution is unlimitedBy analyzing data from a long-duration deployment of four wave-powered unmanned surface vehicles called Wave Gliders, an assessment of operating characteristics informs the potential utility of the Wave Glider in an undersea distributed network as a replacement for a moored communications gateway buoy. Specifically, the wave-powered propulsion system is analyzed to assess endurance, operability, and application in an underwater distributed network as the gateway node. The results of the study serve to identify the parameters for an experiment designed to test the Wave Glider as a station-keeping gateway node.
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Ehsan, ul Haque Muhammad. "Persistence and Node FailureRecovery in Strongly Consistent Key-Value Datastore." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121281.
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Consistency preservation of replicated data is a critical aspect for distributed databaseswhich are strongly consistent. Further, in fail-recovery model each process also needs todeal with the management of stable storage and amnesia [1]. CATS is a key/value datastore which combines the Distributed Hash Table (DHT) like scalability and selforganization and also provides atomic consistency of the replicated items. However beingan in memory data store with consistency and partition tolerance (CP), it suffers frompermanent unavailability in the event of majority failure. The goals of this thesis were twofold (i) to implement disk persistent storage in CATS,which would allow the records and state of the nodes to be persisted on disk and (ii) todesign nodes failure recovery-algorithm for CATS which enable the system to run with theassumption of a Fail Recovery model without violating consistency. For disk persistent storage two existing key/value databases LevelDB [2] and BerkleyDB[3] are used. LevelDB is an implementation of log structured merged trees [4] where asBerkleyDB is an implementation of log structured B+ trees [5]. Both have been used as anunderlying local storage for nodes and throughput and latency of the system with each isdiscussed. A technique to improve the performance by allowing concurrent operations onthe nodes is also discussed. The nodes failure-recovery algorithm is designed with a goalto allow the nodes to crash and then recover without violating consistency and also toreinstate availability once the majority of nodes recover. The recovery algorithm is based onpersisting the state variables of Paxos [6] acceptor and proposer and consistent groupmemberships. For fault-tolerance and recovery, processes also need to copy records from the replicationgroup. This becomes problematic when the number of records and the amount of data ishuge. For this problem a technique for transferring key/value records in bulk is alsodescribed, and its effect on the latency and throughput of the system is discussed.
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Onishchuk, А. "Creating Highly Available Distributed File System for Maui Family Job Schedulers." Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/55757.
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This article describes a way to implement a
distributed file system for MAUI job scheduler, which
solves the problems of low scalability and unreliability
of data storage, as well as a problem of problem of data
inaccessibility due to failures in software or hardware.
The architecture which is suitable for MAUI GRID
systems is suggested.
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Fuchs, Fabian [Verfasser], and D. [Akademischer Betreuer] Wagner. "Algorithms for Efficient Communication in Wireless Sensor Networks - Distributed Node Coloring and its Application in the SINR Model / Fabian Fuchs. Betreuer: D. Wagner." Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1082294470/34.
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Komali, Ramakant S. "Game-Theoretic Analysis of Topology Control." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28358.
Full textAbstract:
Ad hoc networks are emerging as a cost-effective, yet, powerful tool for communication.
These systems, where networks can emerge and converge on-the-fly, are guided by the
forward-looking goals of providing ubiquitous connectivity and constant access to information.
Due to power and bandwidth constraints, the vulnerability of the wireless medium, and
the multi-hop nature of ad hoc networks, these networks are becoming increasingly complex
dynamic systems. Besides, modern radios are empowered to be reconfigurable, which harbors
the temptation to exploit the system. To understand the implications of these issues, some
of which pose significant challenges to efficient network design, we study topology control
using game theory.
We develop a game-theoretic framework of topology control that broadly captures the radio
parameters, one or more of which can be tuned under the purview of topology control. In
this dissertation, we consider two parameters, viz. transmit power and channel, and study
the impact of controlling these on the emergent topologies.
We first examine the impact of node selfishness on the network connectivity and energy
efficiency under two levels of selfishness: (a) nodes cooperate and forward packets for one
another, but selfishly minimize transmit power levels and; (b) nodes selectively forward
packets and selfishly control transmit powers. In the former case, we characterize all the
Nash Equilibria of the game and evaluate the energy efficiency of the induced topologies.
We develop a better-response-based dynamic that guarantees convergence to the minimal
maximum power topology. We extend our analysis to dynamic networks where nodes have
limited knowledge about network connectivity, and examine the tradeoff between network
performance and the cost of obtaining knowledge. Due to the high cost of maintaining
knowledge in networks that are dynamic, mobility actually helps in information-constrained
networks. In the latter case, nodes selfishly adapt their transmit powers to minimize their
energy consumption, taking into account partial packet forwarding in the network. This
work quantifies the energy efficiency gains obtained by cooperation and corroborates the
need for incentivizing nodes to forward packets in decentralized, energy-limited networks.
We then examine the impact of selfish behavior on spectral efficiency and interference minimization
in multi-channel systems. We develop a distributed channel assignment algorithm
to minimize the spectral footprint of a network while establishing an interference-free connected
network. In spite of selfish channel selections, the network spectrum utilization is
shown to be within 12% of the minimum on average. We then extend the analysis to dynamic
networks where nodes have incomplete network state knowledge, and quantify the price of
ignorance. Under the limitations on the number of available channels and radio interfaces, we
analyze the channel assignment game with respect to interference minimization and network
connectivity goals. By quantifying the interference in multi-channel networks, we illuminate
the interference reduction that can be achieved by utilizing orthogonal channels and by distributing
interference over multiple channels. In spite of the non-cooperative behavior of
nodes, we observe that the selfish channel selection algorithm achieves load balancing.
Distributing the network control to autonomous agents leaves open the possibility that nodes
can act selfishly and the overall system is compromised. We advance the need for considering
selfish behavior from the outset, during protocol design. To overcome the effects of
selfishness, we show that the performance of a non-cooperative network can be enhanced by
appropriately incentivizing selfish nodes.Ph. D.
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Diarra, Amadou. "Vers une prise en charge des comportements rationnels dans les systèmes distribués." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAM074/document.
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De nos jours, la notion de responsabilité dans un système distribué est devenue quasiment incontournable dans les techniques de détection de fautes. Elle permet non seulement de détecter les fautes mais aussi de fournir des preuves de dysfonctionnement contre les noeuds fautifs dans un système distribué. Les noeuds dits rationnels, c'est-à-dire des noeuds qui essayent de tirer profit du système en maximisant leur bénéfice sans y contribuer en, sont un exemple.Dans la littérature, il existe deux types de solutions exploitant cette notion : les solutions spécifiques et les solutions génériques.Les solutions spécifiques sont relatives à un type de système distribué donné et se construisent en tenant compte de la structure du système et de l'application qui s'y exécute. Les solutions génériques quant à elles, sont indépendantes du système.Dans cette thèse nous nous intéressons au second type de solutions c'est à dire les solutions génériques. Dans cette classe de solutions, il existe deux approches pour mettre en place la notion de responsabilité : l'approche matérielle et l'approche logicielle.Actuellement le seul protocole logiciel, générique qui permet d'assurer la notion de responsabilité dans un système distribué, est le protocole PeerReview.Ce protocole n'est basé sur une aucune configuration matérielle. Cependant, il n'est pas robuste aux comportements dits rationnels au sein de ses propres étapes.Notre objectif est de fournir une solution logicielle sous-jacente renforçant la notion de responsabilité au niveau d'une application qui s'exécute sur un système distribué en présence de noeuds rationnels.Pour ce faire nous proposons FullReview un protocole qui se base sur la théorie des jeux pour motiver et forcer les noeuds rationnels à suivre les différentes étapes, non seulement au niveau de son propre protocole mais aussi au niveau de l'application qu'il surveille. En outre, FullReview utilise l'architecture classique d'un système responsable, qui associe à chaque noeud un ensemble de noeuds appelés moniteurs ou surveillants, et ayant un rôle de surveillance périodique du noeud en question.Nous prouvons théoriquement que notre protocole est un équilibre de Nash, c'est-à-dire que les noeuds rationnels n'ont aucun intérêt à dévier du protocole.Ce genre de protocole étant coûteux en terme d'échanges de messages, nous nous sommes intéressés à l'étude théorique des différentes techniques de gestion des moniteurs ou surveillants.L'objectif de cette étude est d'identifier les conditions sur les paramètres du protocole pour lesquelles une méthode de gestion convient mieux qu'une autre.De plus nous évaluons notre protocole en l'appliquant à deux applications largement utilisées : SplitStream, un protocole efficace pour la multi-diffusion de flux vidéo et Onion Routing, le protocole de communication anonyme le plus utilisé. Les résultats montrent que FullReview détecte efficacement les comportements rationnels avec un faible surcoût comparé au protocole PeerReview et passe à l'échelle comme ce dernierAccountability is becoming increasingly required in today's distributed systems. It allows not only to detect faults but also to build provable evidence about the misbehaving nodes in a distributed system. Rational nodes that aim at maximising their benefit without contributing their fair share to the system, are an example. In the literature, there exists two types of solutions that exploit accountability: specific solutions and generic solutions.Specific solutions are related to a given type of distributed system and are built by taking into account the structure of the system and the running application. As for generic solutions, they are independent to the system.In this thesis we consider the second type of solutions i.e., generic solutions. There exists two approaches in this class of solutions: hardware approach and software approach. Nowadays the only software and generic protocol that allows to enforce accountability in a distributed system is PeerReview protocol. This protocol is not based on any hardware configuration. However, it is not robust to rational behaviour in its own steps.Our objective is to provide a generic software solution to enforce accountability on any underlying application that running on a distributed system in presence of rational nodes.To reach this goal we propose FullReview a protocol that uses game theory to motivate and force rational participants to follow different steps, not only in its own protocol but also in the application that it monitors. Moreover FullReview uses the classical architecture of an accountable system. This architecture assigns to each node in the system, a set of nodes called monitors. Periodically each node is monitored by its set of monitors.We theoretically prove that our protocol is a Nash equilibrium, i.e., nodes do not have any interest in deviating from it.This kind of protocol being costly in terms of messages exchanged, we are interested to the theoretic study of different techniques of monitors management. The objective of this study is to identify conditions on protocol parameters for which a method of management is more appropriate than another.Furthermore, we practically evaluate FullReview by deploying it for enforcing accountability in two applications: (1) SplitStream, an efficient multicast protocol for live streaming, and (2) Onion Routing, the most widely used anonymous communication protocol. Performance evaluation shows that FullReview effectively detects faults in presence of rational nodes while introducing a small overhead compared to PeerReview and scaling as PeerReview
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Fic, Jiří. "Virtuální prostředí přístupu k uzlům v PlanetLab." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2008. http://www.nusl.cz/ntk/nusl-236003.
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PlanetLab as a distributed systems testbed offers a unique opportunity for developing and testing new applications useful for future Internet. This work brings up a scheme and a solution of the problem with accessing PlanetLab by a larger group of students e.g. for the purpose of solving their courseworks. A designed system empowers its administrator to create and control virtual user accounts which provide possibility for all its users to connect to selected nodes in the PlanetLab.
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Křek, Radim. "Distribuovaný řídicí systém s dynamicky modifikovatelnými uzly." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2019. http://www.nusl.cz/ntk/nusl-399165.
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This thesis describes creation of dynamically evolvable node, which will cooperate with other nodes. Group of these nodes will then create a distributed control system. The MQTT protocol is used for communications purposes between individual nodes. As hardware platform is used ESP32 and ESP8266. Whole operating system is written in MicroPython and supports a live uploading of user applications written in the same language. Later in thesis is decribed creation of monitoring node on Raspberry Pi, which control network. Complete system can be then used to control a intelligent house.
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Shi, Hong-Ling. "Development of an energy efficient, robust and modular multicore wireless sensor network." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2014. http://tel.archives-ouvertes.fr/tel-00968069.
Full textAbstract:
The wireless sensor network is a key technology in the 21st century because it has multitude applications and it becomes the new way of interaction between physical environment and computer system. Moreover, the wireless sensor network is a high resource constraint system. Consequently, the techniques used for the development of traditional embedded systems cannot be directly applied. Today wireless sensor nodes were implemented by using only one single processor architecture. This approach does not achieve a robust and efficient energy wireless sensor network for applications such as precision agriculture (outdoor) and telemedicine. The aim of this thesis is to develop a new approach for the realization of a wireless sensor network node using multicore architecture to enable to increase both its robustness and lifetime (reduce energy consumption).
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Jmila, Houda. "Dynamic resource allocation and management in virtual networks and Clouds." Thesis, Evry, Institut national des télécommunications, 2015. http://www.theses.fr/2015TELE0023/document.
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L’informatique en nuage (Cloud computing) est une technologie prometteuse facilitant la réservation et de l'utilisation des ressources d’une manière flexible et dynamique. En plus des ressources informatiques traditionnelles, les utilisateurs du Cloud attendent à ce que des ressources réseaux leurs soient dédiées afin de faciliter le déploiement des fonctions et services réseau. Ils souhaitent pouvoir gérer l'ensemble d'un réseau virtuel (VN) ou infrastructure. Ainsi, les fournisseurs du Cloud doivent déployer des solutions de provisionnement des ressources dynamiques et adaptatives afin d’allouer des réseaux virtuels qui reflètent les besoins variables dans le temps des applications hébergés dans le Cloud. L’état de l’art sur l’allocation des réseaux virtuels s’est uniquement intéressé au problème de mapping des nœuds et liens virtuels composant une demande de réseau virtuel dans les nœuds et chemins du réseau de physique (infrastructure Cloud), connu sous le nom du problème de virtual network embedding (VNE). Peu d'attention a été accordée à la gestion des ressources allouées pour répondre en permanence aux besoins variables des réseaux virtuels hébergés dans le réseau physique et afin d'assurer une utilisation efficace des ressources. L'objectif de cette thèse est de permettre l'allocation des réseaux virtuels d’une manière dynamique et préventive pour faire face aux fluctuations de la demande au cours de la durée de vie du réseau virtuel, et pour améliorer l'utilisation des ressources du substrat. Pour atteindre ces objectifs, la thèse propose d'adaptation des algorithmes d'allocation des ressources pour répondre à l’évolution des demandes du réseau virtuel. Premièrement, nous allons étudier en profondeur l'extension d'un nœud virtuel, à savoir le cas où un nœud virtuel hébergé nécessite plus de ressources alors le nœud physique qui l’héberge n'a pas assez de ressources disponibles. Deuxièmement, nous allons améliorer la proposition précédente afin de considérer la rentabilité du réseau de substrat. Et enfin, nous allons gérer la variation de la demande en bande passante dans les liens virtuels. Par conséquent, la première partie de cette thèse fournit un algorithme heuristique qui traite la fluctuation de la demande dans les nœuds virtuels. L'idée principale de l'algorithme est de réallouer un ou plusieurs nœuds virtuels co-localisés dans du nœud de substrat, qui héberge le nœud en évolution pour libérer des ressources (ou faire de la place) pour le nœud en évolution. En plus de réduire le coût de réaffectation, notre proposition prend en compte et réduit l'interruption de service pendant la migration. L'algorithme précédent a été étendu pour concevoir un algorithme de reconfiguration préventif pour améliorer la rentabilité du réseau physique. En fait, notre proposition profite de la perturbation de la demande de ressources pour ranger le réseau physique à un coût minimal et sans perturbations. Lors de la réaffectation des nœuds virtuels pour faire place pour le nœud en extension, nous réaffectant les liens virtuels les plus congestionnées dans des ressources physiques moins saturées afin d’équilibrer la charge sur le réseau. Notre proposition offre le meilleur compromis entre le coût de réaffectation et l'équilibrage des charges. Enfin, un framework distribué, parallèle et à vue locale a été mis au point pour traiter toutes les formes de fluctuations de la demande en bande passante dans les liens virtuels. Elle se compose d'un contrôleur et trois algorithmes exécutés dans chaque nœud du substrat d'une manière distribuée et parallèle. Le framework est basé sur l'auto-stabilisation, et peut gérer de nombreuses et différentes formes de variations de la demande de bande passante simultanémentCloud computing is a promising technology enabling IT resources reservation and utilization on a pay-as-you-go manner. In addition to the traditional computing resources, cloud tenants expect compete networking of their dedicated resources to easily deploy network functions and services. They need to manage an entire Virtual Network (VN) or infrastructure. Thus, Cloud providers should deploy dynamic and adaptive resource provisioning solutions to allocate virtual networks that reflect the time-varying needs of Cloud-hosted applications. Prior work on virtual network resource provisioning only focused on the problem of mapping the virtual nodes and links composing a virtual network request to the substrate network nodes and paths, known as the Virtual network embedding (VNE) problem. Little attention was paid to the resource management of the allocated resources to continuously meet the varying demands of embedded virtual networks and to ensure efficient substrate resource utilization. The aim of this thesis is to enable dynamic and preventive virtual network resources provisioning to deal with demand fluctuation during the virtual network lifetime, and to enhance the substrate resources usage. To reach these goals, the thesis proposes adaptive resource allocation algorithms for evolving virtual network requests. We adress the extension of an embedded virtual node requiring more resources and consider the substrate network profitability. We also deal with the bandwidth demand variation in embedded virtual links. We first provide a heuristic algorithm to deal with virtual nodes demand fluctuation. The work is extended by designing a preventive re-configuration scheme to enhance substrate network profitability. Finally, a distributed, local-view and parallel framework was devised to handle embedded virtual links bandwidth fluctuations. The approach is composed of a controller and three algorithms running in each substrate node in a distributed and parallel manner. The framework is based on the self-stabilization approach, and can manage various forms of bandwidth demand variations simultaneously
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Rupolo, Diogo [UNESP]. "Planejamento integrado de redes de distribuição de energia elétrica com fontes renováveis de geração distribuída na média e baixa tensão." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151582.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho propõem-se metodologias para realizar o planejamento de sistemas de distribuição de energia elétrica de média tensão (MT), baixa tensão (BT) e o planejamento integrado de sistemas de média e baixa tensão (MT/BT). Nos modelos de funções objetivos considerados minimizam-se os custos associados à construção, expansão, operação e confiabilidade das redes de MT, BT e MT/BT, considerando a presença de geradores distribuídos e variáveis de natureza estocástica. A geração distribuída presente no planejamento de sistemas de distribuição é avaliada através de metodologias de geração de cenários e análise de risco. Como método de busca de soluções para o problema de planejamento dos sistemas de distribuição é proposta a meta-heurística de busca em vizinhança variável GVNS (General Variable Neighborhood Search). A meta-heurística GVNS trabalha com uma série de estruturas de vizinhanças que permitem explorar o espaço de busca de forma eficiente através dos critérios de diversificação e intensificação, aumentando a probabilidade de obter soluções que não sejam ótimos locais. No planejamento integrado MT/BT, as soluções obtidas são analisadas através de um fluxo de potência integrado entre as redes de MT e BT, considerando as relações de conexão dos transformadores entre estes sistemas. Os algoritmos propostos relacionados ao planejamento de sistemas MT, BT e MT/BT são implementados em linguagem de programação C++ e testado em diferentes sistemas testes de MT (54 barras e 182 barras), BT (76 barras) e MT/BT (172 e 412 barras), sob diferentes cenários operacionais.
This work proposes methodologies for the planning of medium voltage (MV), low voltage (LV), and integrated planning of medium and low voltage (MV/LV) systems. In the objective function models are considered the costs associated with the construction, expansion, operation and reliability of MV, LV and integrated MV/LV networks. Distributed generators and stochastic variables are also considered in the models. The distributed generation present in the planning of distribution systems is evaluated through methodologies of scenario generation and risk analysis. As a method of finding solutions to the problem of distribution system planning, the GVNS metaheuristic (General Variable Neighborhood Search) is proposed. The metaheuristic GVNS works with a series of neighborhood structures that allow to explore the search space efficiently through diversification and intensification criteria, increasing the probability of obtaining solutions that are not local optimum. In integrated MV/LV planning, the solutions obtained are analyzed through an integrated power flow between the MV and LV networks, considering the connection ratios of the transformers between these systems. The proposed algorithms related to the planning of MV, LV and integrated MV/LV systems are implemented in C ++ programming language and tested in different distribution systems, MV (54 and 182 bus), LV (76 bus) and MV/LV (172 and 412 bus), under different operating scenarios.
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Rupolo, Diogo. "Planejamento integrado de redes de distribuição de energia elétrica com fontes renováveis de geração distribuída na média e baixa tensão /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151582.
Full textAbstract:
Orientador: Jose Sanches MantovaniResumo: Neste trabalho propõem-se metodologias para realizar o planejamento de sistemas de distribuição de energia elétrica de média tensão (MT), baixa tensão (BT) e o planejamento integrado de sistemas de média e baixa tensão (MT/BT). Nos modelos de funções objetivos considerados minimizam-se os custos associados à construção, expansão, operação e confiabilidade das redes de MT, BT e MT/BT, considerando a presença de geradores distribuídos e variáveis de natureza estocástica. A geração distribuída presente no planejamento de sistemas de distribuição é avaliada através de metodologias de geração de cenários e análise de risco. Como método de busca de soluções para o problema de planejamento dos sistemas de distribuição é proposta a meta-heurística de busca em vizinhança variável GVNS (General Variable Neighborhood Search). A meta-heurística GVNS trabalha com uma série de estruturas de vizinhanças que permitem explorar o espaço de busca de forma eficiente através dos critérios de diversificação e intensificação, aumentando a probabilidade de obter soluções que não sejam ótimos locais. No planejamento integrado MT/BT, as soluções obtidas são analisadas através de um fluxo de potência integrado entre as redes de MT e BT, considerando as relações de conexão dos transformadores entre estes sistemas. Os algoritmos propostos relacionados ao planejamento de sistemas MT, BT e MT/BT são implementados em linguagem de programação C++ e testado em diferentes sistemas testes de MT (54 barras e 182... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Tushar, Wayes. "Signal processing for distributed nodes in smart networks." Phd thesis, 2012. http://hdl.handle.net/1885/10295.
Full textAbstract:
With increasing environmental concern for energy conservation and mitigating climate change, next generation smart networks are bound to provide improved performance in terms of security, reliability, and energy efficiency. For instance, future smart networks will work in highly complex and dynamic environments and will have distributed nodes that need to interact with each other and may also interact with an energy provider in order to improve their performance. In this context, advanced signal processing tools such as game theory and distributed transmit beamforming can yield tremendous performance gains in terms of energy efficiency for demand management and signal trans-mission in smart networks.
The central theme of this dissertation is the modeling of energy usage behavior of self-seeking distributed nodes in smart networks. The thesis mainly looks into two key areas of smart networks: 1) smart grid networks and 2) wireless sensor networks, and contains: an analytical framework of the economics of electric vehicle charging in smart grids in an energy constrained environment; a study of a consumer-centric energy management scheme for encouraging the consumers in a smart grid to voluntarily take part in energy management; an outage management scheme for efficiently curtailing energy from the consumers in smart grids in the event of a power outage; a comprehensive study of power control of sensors in a wireless sensor network using game theory and distributed transmit beamforming; and finally, an energy aware distributed transmit beamfoming technique for long distance signal transmission in a wireless sensor network.
This thesis addresses the challenges of modeling the energy usage behavior of distributed nodes through studying the propriety of energy users in smart networks, 1) by capturing the interactions between the energy users and energy provider in smart grids using non-cooperative Stackelberg and generalized Nash games, and showing that the socially optimal energy management for users can be achieved at the solution of the games, and 2) by studying the power control of sensors in wireless sensor networks, using a non-cooperative Nash game and distributed transmit beamforming that demonstrates significant transmit energy savings for the sensors. To foster energy efficient transmission, the thesis also studies a distributed transmit beamforming technique that does not require any channel state information for long distance signal transmission in sensor networks.
The contributions of this dissertation are enhanced by proposing suitable system models and appropriate signal processing techniques. These models and techniques can capture the different cost-benefit tradeoffs that exist in these networks. All the proposed schemes in this dissertation are shown to have significant performance improvement when compared with existing solutions. The work in this thesis demonstrates that modeling power usage behavior of distributed nodes in smart networks is both possible and beneficial for increasing the energy efficiency of these networks.
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Beal, Jacob. "A Robust Amorphous Hierarchy from Persistent Nodes." 2003. http://hdl.handle.net/1721.1/6717.
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For a very large network deployed in space with only nearby nodes able to talk to each other, we want to do tasks like robust routing and data storage. One way to organize the network is via a hierarchy, but hierarchies often have a few critical nodes whose death can disrupt organization over long distances. I address this with a system of distributed aggregates called Persistent Nodes, such that spatially local failures disrupt the hierarchy in an area proportional to the diameter of the failure. I describe and analyze this system, which has been implemented in simulation.
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Lin, Che-Ming, and 林哲民. "Distributed Work Scheduling for Wireless Sensor Nodes Using Game Theory." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/23187010624743195130.
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碩士國立高雄大學
資訊工程學系碩士班
99
In wireless sensor network, there are several sensors and targets. All targets have to be monitored by sensors. Each target has a coverage level requirement. The targets can satisfy requirements by opening a part of the sensors. The paper research how to schedule the sensors. The power consumption can be reduced, and the network life time can be extended. The traditional methods almost use the greedy methods and the heuristic algorithms to solve the problem. In this paper, we employ Game Theory to solve it. The sensor selects whether to open the power or not. We prove that the game we defined can converge to a stable state, and the simulation result show it can extend the network life time. But the time that a game converges to a stable state has to be regarding as a cost. We propose two solutions to get the stable state more quickly. By simulation result, reaching stable state quickly leads to the little reduction of the network life time. The result is very good.
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Beal, Jacob. "Persistent Nodes for Reliable Memory in Geographically Local Networks." 2003. http://hdl.handle.net/1721.1/6712.
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A Persistent Node is a redundant distributed mechanism for storing a key/value pair reliably in a geographically local network. In this paper, I develop a method of establishing Persistent Nodes in an amorphous matrix. I address issues of construction, usage, atomicity guarantees and reliability in the face of stopping failures. Applications include routing, congestion control, and data storage in gigascale networks.
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"Detecting Sybil Nodes in Static and Dynamic Networks." Doctoral diss., 2010. http://hdl.handle.net/2286/R.I.8797.
Full textAbstract:
abstract: Peer-to-peer systems are known to be vulnerable to the Sybil attack. The lack of a central authority allows a malicious user to create many fake identities (called Sybil nodes) pretending to be independent honest nodes. The goal of the malicious user is to influence the system on his/her behalf. In order to detect the Sybil nodes and prevent the attack, a reputation system is used for the nodes, built through observing its interactions with its peers. The construction makes every node a part of a distributed authority that keeps records on the reputation and behavior of the nodes. Records of interactions between nodes are broadcast by the interacting nodes and honest reporting proves to be a Nash Equilibrium for correct (non-Sybil) nodes. In this research is argued that in realistic communication schedule scenarios, simple graph-theoretic queries such as the computation of Strongly Connected Components and Densest Subgraphs, help in exposing those nodes most likely to be Sybil, which are then proved to be Sybil or not through a direct test executed by some peers.Dissertation/Thesis
Ph.D. Computer Science 2010