Dissertations / Theses on the topic 'Distribution Networks'
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Masood, Syed Haani. "Distribution of files using network-coding in opportunistic networks." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106560.
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The immense growth in mobile data usage has placed mobile operators in a challenging position. User experience is threatened to degrade due to network capacity issues. The route towards network upgrades is an expensive one especially due to the high licensing fees attached to spectrum acquisition. We propose a scheme based on community identification for distributing large files to subscribers using opportunistic communication. The scheme is able to offload large files from the cellular network and without having to invest in any infrastructure. The cellular network initially seeds the file to the most central subscriber in each community which is then spread to all subscribers via opportunistic contacts. Network coding is utilized for the opportunistic exchange of file packets between subscribers. We show that seeding the file in each community is important to ensure better file delivery times and also reduces the overhead of the number of packet exchanges required during file dissemination. Our scheme also provides incentives for influential subscribers in the network which contribute more towards the opportunistic dissemination of file.L'immense croissance de l'utilisation des données mobiles a placé les opérateurs mobiles dans une position difficile. L'expérience utilisateur est menacée de se dégrader en raison de problèmes de capacité du réseau. La route vers la mise à niveau du réseau est coûteuse en particulier en raison des frais de licence élevés attachés à l'acquisition du spectre. Nous proposons un schéma basé sur l'identification communautaire pour la distribution de gros fichiers à des abonnés en utilisant la communication opportuniste. Le système est capable de se décharger de gros fichiers sur le réseau cellulaire et sans avoir à investir dans n'importe quelle infrastructure. Le réseau cellulaire d'abord les graines du fichier à l'abonné la plus centrale dans chaque communauté, qui est ensuite étendue à tous les abonnés via des contacts opportunistes. Réseau de codage est utilisé pour l'échange de paquets de fichiers opportunistes entre les abonnés. Nous montrons que l'ensemencement du fichier dans chaque communauté est important pour assurer une meilleure délais de livraison du fichier et réduit également la surcharge du nombre d'échanges de paquets nécessaires pendant la diffusion de fichiers. Notre programme prévoit également des incitations pour les abonnés influents dans le réseau qui contribuent davantage vers la diffusion opportuniste de fichier.
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Zhou, Lin. "Active network management and uncertainty analysis in distribution networks." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675697.
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In distribution networks, the traditional way to eliminate network stresses caused by increasing generation and demand is to reinforce the primary network assets. A cheaper alternative is active network management (ANM) which refers to real-time network control to resolve power flow, voltage, fault current and security issues. However, there are two limitations in ANM. First, previous ANM strategies investigated generation side and demand side management separately. The generation side management evaluates the value from ANM in terms of economic generation curtailment. It does not consider the potential benefits from integrating demand side response such as economically shifting flexible load over time. Second, enhancing generation side management with load shifting requires the prediction of network stress whose accuracy will decrease as the lead time increases. The uncertain prediction implies the potential failure of reaching expected operational benefits. However, there is very limited investigation into the trade-offs between operational benefit and its potential risk. In order to tackle the challenges, there are two aspects of research work in this thesis. 1) Enhanced ANM. It proposes the use of electric vehicles (EVs) as responsive demand to complement generation curtailment strategies in relieving network stress. This is achieved by shifting flexible EV charging demand over time to absorb excessive wind generation when they cannot be exported to the supply network. 2) Uncertainty management. It adopts Sharpe Ratio and Risk Adjust Return On Capital concepts from financial risk management to help the enhanced ANM make operational decisions when both operational benefit and its associated risk are considered. Copula theory is applied to further integrate correlations of forecasting errors between nodal power injections (caused by wind and load forecasting) into uncertainty management. The enhanced ANM can further improve network efficiency of the existing distribution networks to accommodate increasing renewable generation. The cost-benefit assessment informs distribution network operators of the trade-off between investment in ANM strategy and in the primary network assets, thus helping them to make cost-effective investment decisions. The uncertainty management allows the impact of risks that arise from network stress prediction on the expected operational benefits to be properly assessed, thus extending the traditional deterministic cost-benefit assessment to cost-benefit-risk assessment. Moreover, it is scalable to other systems in any size with low computational burden, which is the major contribution of this thesis.
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Weinstein, Lee. "Scale free networks and their power law distribution." Diss., Connect to the thesis, 2005. http://hdl.handle.net/10066/3880.
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Memarian, Neda. "Resilience of Water Distribution Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Resilience is widely interpreted as the capacity of a system to resist (preparation phase), absorb and withstand (responding phase), and rapidly recover from (restoration phase) exceptional conditions. During this study, a mixed variety of calculations were assessed in order to find the best solution for determination of resilience and reliability of a simple network. Then, Todini’s formula and failure index was applied to estimate reliability of system in different scenarios as constant demands in period of 24 hours, constant demands in period of 72 hours when tank will be empty (failure of tank), variable demands in period of 24 hours. At first hydraulic simulation of those scenarios was done by EPANET and validated by MATLAB-TOOLKIT. Then, Resilience index (RI), Failure Index (FI) and reliability (R) of system were measured. Finally, an optimization procedure was done to make a water distribution network with highest resilience and lowest failure probability. All these procedures have been applied on a real network as WDS of Modena. It concluded that this method can be used for every water system without considering the type of failure. As a result, first scenario has a constant decreased and increased trend of RI and FI respectively because of diminishing of water level in tank. During second scenario, there is significant change after the tank will be empty (or it is broke). Third scenario is more like a real network with variable demand during a day. It was concluded that there is a minimum resilience parameter during day when a peak time of water demand expected. It can be justified that the reservoir and pump system had to sustain more pressure to satisfy the demands of junctions. Maximum resilience is related to night during a day with less demands and providing water by tank to other junctions. This modelling could be useful to optimize the dimensions and features of instruments to increase availability and reliability of system.
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Ozdem, Mehmet. "Video Distribution Over Ip Networks." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608187/index.pdf.
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As applications like IPTV and VoD (Video on demand) are gaining popularity, it is becoming
more important to study the behavior of video signals in the Internet access infrastructures
such as ADSL and cable networks. Average delay, average jitter and packet loss in these
networks affect the quality of service, hence transmission and access speeds need to be
determined such that these parameters are minimized.
In this study the behavior of the above mentioned IP networks under variable bit rate (VBR)
video traffic is investigated. ns-2 simulator is used for this purpose and actual as well as
artificially generated signals are applied to the networks under test. Variable bit rate (VBR)
traffic is generated synthetically using ON/OFF sources with ON/OFF times taken from
exponential or Pareto distributions. As VBR video shows long range dependence with a Hurst
parameter between 0.5 and 1, this parameter was used as a metric to measure the accuracy of
the synthetic sources. Two different topologies were simulated in this study: one similar to
ADSL access networks and the other behaving like cable distribution network. The
performance of the networks (delay, jitter and packet loss) under VBR video traffic and
different access speeds were measured. According to the obtained results, minimum access
speeds in order achieve acceptable quality video delivery to the customers were suggested.
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Ar, Kerem. "Calibration Of Water Distribution Networks." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12613934/index.pdf.
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Water distribution network models are used for different purposes. In this study, a model, used for daily operational issues is concerned. Models results should be consistent with actual conditions for sound decisions during operational studies. Adjusting model parameters according to site measurements in order to fit the model to obtain realistic results is known as calibration. Researchers have carried out numerous studies on calibration and developed various methods. In this study, an actual network (N8.3 Pressure Zone, Ankara) has been calibrated by two classical methods developed by Walski (1983) and Bhave (1988). The network parameter calibrated in this study is Hazen-Williams roughness coefficient, C-factor, and other parameters have been lumped in the C-factor. Results of the analysis showed that, C-factors have been found in a wide range.
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Sendil, Halil. "Operation Of Water Distribution Networks." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615484/index.pdf.
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With continuously increasing urbanization, consumer demands and expansion of water supply systems, determination of efficient pump schedules became a more difficult task. Pumping energy costs constitute a significant part of the operational cost of the water distribution networks. This study aims to provide an effective daily pump schedule by minimizing the energy costs for constant and also for multi tariff of electricity (3 Kademeli Elektrik Tarifesi) in water distribution network. A case study has been performed in an area covering N8.3 and N7 pressure zones which are parts of Ankara water distribution network. Both pressure zones consists of 3 multiple pumps in pump station and one tank having 5000 m3 storage volume each. By using genetic algorithm based software (WaterCAD Darwin Scheduler) least-cost pump scheduling and operation policy for each pump station has been determined while satisfying target hydraulic performance requirements such as minimum and maximum service pressures, final water level of storage tank and maximum velocity in pipeline. 32 different alternative scenarios have been created which include multi tariff energy prices, constant tariff energy price, insulated system condition, uninsulated system condition and different pump combinations. The existing base scenario and alternative scenarios which were prepared by using optimal pump schedules have been compared and the achievements of optimizing pump operation have been analyzed. At the end of the study, a satisfying result has been observed that by using determined optimal pump schedule, minimum % 14 of total energy cost can be saved in existing water supply system.
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Khelifa, Abdelghafor. "Design of optimal distribution networks." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46391.
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Cobelo, I. "Active control of distribution networks." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685442.
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Nasiev, Diar. "Statistical mechanics of distribution networks." Thesis, Aston University, 2009. http://publications.aston.ac.uk/15362/.
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We present a stability analysis against cascading failures. We propose a spin [binary] model, based on concepts of statistical mechanics. We test macroscopic properties of distribution networks with respect to various topological structures and distributions of microparameters. The equilibrium properties of the systems are obtained in a statistical mechanics framework by application of the replica method. We demonstrate the validity of our approach by comparing it with Monte Carlo simulations. We analyse the network properties in terms of phase diagrams and found both qualitative and quantitative dependence of the network properties on the network structure and macroparameters. The structure of the phase diagrams points at the existence of phase transition and the presence of stable and metastable states in the system. We also present an analysis of robustness against overloading in the distribution networks.
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Nowatkowski, Michael E. "Certificate revocation list distribution in vehicular ad hoc networks." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33971.
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The objective of this research is to investigate improved methods for distributing certificate revocation lists (CRLs) in vehicular ad hoc networks (VANETs). VANETs are a subset of mobile ad hoc networks composed of network-equipped vehicles and infrastructure points, which will allow vehicles to communicate with other vehicles and with roadside infrastructure points. While sharing some of the same limitations of mobile ad hoc networks, such as lack of infrastructure and limited communications range, VANETs have several dissimilarities that make them a much different research area. The main differences include the size of the network, the speed of the vehicles, and the network security concerns. Confidentiality, authenticity, integrity, and availability are some of the standard goals of network security. While confidentiality and authenticity at times seem in opposition to each other, VANET researchers have developed many methods for enhancing confidentiality while at the same time providing authenticity. The method agreed upon for confidentiality and authenticity by most researchers and the IEEE 1609 working group is a public key infrastructure (PKI) system. An important part of any PKI system is the revocation of certificates. The revocation process, as well as the distribution of revocation information, is an open research problem for VANETs. This research develops new methods of CRL distribution and compares them to existing methods proposed by other researchers. The new methods show improved performance in various vehicle traffic densities.
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Gu, Chenghong. "Long-run network pricing for security of supply in distribution networks." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527128.
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Cuquet, Palau Martí. "Entanglement distribution in quantum complex networks." Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/107850.
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Aquesta tesi tracta l’estudi de xarxes quàntiques amb una estructura complexa, les implicacions que aquesta estructura té en la distribució d’entrellaçament i com el seu funcionament pot ser millorat mitjançant operacions en el règim quàntic. Primer considerem xarxes complexes d’estats bipartits, tant purs com mescla, i estudiem la distribució d’entrellaçament a llargues distàncies. Després passem a analitzar xarxes de canals sorollosos i estudiem la creació i distribució de grans estats multipartits.
El treball contingut en aquesta tesi està motivat principalment per la idea que la interacció entre la informació quàntica i les xarxes complexes pot donar lloc a una nova comprensió i caracterització dels sistemes naturals. Les xarxes complexes tenen una importància particular en les infraestructures de comunicació, ja que la majoria de xarxes de telecomunicació tenen una estructura complexa. En el cas de xarxes quàntiques, que són el marc necessari per al processament distribuït d’informació i comunicació quàntica, és ben possible que en el futur adquireixin una topologia complexa semblant a la de les xarxes existents, o que fins i tot es desenvolupin mètodes per a utilitzar les infraestructures actuals en el règim quàntic.
Una tasca central en les xarxes quàntiques és dissenyar estratègies per distribuir entrellaçament entre els seus nodes. En la primera part d’aquesta tesi, considerem la distribució d’entrellaçament bipartit com un procés de percolació d’entrellaçament en una xarxa complexa. Des d’aquest enfocament, s’estableix entrellaçament perfecte de manera probabilística entre dos nodes arbitraris. Veiem que, per a xarxes grans, la probabilitat d’aconseguir-ho és una constant estrictament major que zero (i independent de la mida de la xarxa) si la quantitat inicial d’entrellaçament està per sobre d’un cert valor crític. La mecànica quàntica ofereix aquí la possibilitat de canviar l’estructura de la xarxa sense necessitat d’establir nous canals “físics”. Mitjançant una transformació local adequada de la xarxa, es pot disminuir l’entrellaçament crític i augmentar la probabilitat. Apliquem aquesta transformació a models de xarxes complexes amb una distribució de graus arbitrària.
En el cas de xarxes sorolloses d’estats mescla, veiem que per algunes classes d’estat es pot utilitzar el mateix enfocament de percolació d’entrellaçament. Per a estats mescla generals considerem una percolació de llargada de camí limitada per la quantitat de soroll de les connexions. Veiem com les xarxes complexes ofereixen encara un gran avantatge en la probabilitat de connectar dos nodes.
En la segona part, passem a l’escenari multipartit. Estudiem la creació i distribució d’estats graf amb una estructura que imita la de la xarxa de comuicació subjacent. En aquest cas, utilitzem una xarxa complexa arbitrària amb canals sorollosos, i considerem que les operacions i mesures són també sorolloses. Proposem un mètode eficient per a distribuir i purificar petits subgrafs, que després es fusionen per a reproduir l’estat desitjat. Comparem aquest enfocament amb dos protocols bipartits basats en un node central i coneixement complet de l’estructura de la xarxa. Mostrem que la fidelitat dels estats graf generats es pot escriure com la funció de partició d’un sistema desordenat de spins clàssics (un vidre de spins), i la seva taxa de decaïment és l’anàleg de l’energia lliure. Utilitzant els tres protocols en una xarxa unidimensional i en xarxes complexes veiem que són tots comparables, i que en alguns casos el protocol de subgrafs proposat, que necessita només informació local de la xarxa, té inclús un comportament millor.This thesis deals with the study of quantum networks with a complex structure, the implications this structure has in the distribution of entanglement and how their functioning can be enhanced by operating in the quantum regime. We first consider a complex network of bipartite states, both pure and mixed, and study the distribution of long-distance entanglement. Then, we move to a network with noisy channels and study the creation and distribution of large, multipartite states. The work contained in this thesis is primarily motivated by the idea that the interplay between quantum information and complex networks may give rise to a new understanding and characterization of natural systems. Complex networks are of particular importance in communication infrastructures, as most present telecommunication networks have a complex structure. In the case of quantum networks, which are the necessary framework for distributed quantum processing and for quantum communication, it is very plausible that in the future they acquire a complex topology resembling that of existing networks, or even that methods will be developed to use current infrastructures in the quantum regime. A central task in quantum networks is to devise strategies to distribute entanglement among its nodes. In the first part of this thesis, we consider the distribution of bipartite entanglement as an entanglement percolation process in a complex network. Within this approach, perfect entanglement is established probabilistically between two arbitrary nodes. We see that for large networks, the probability of doing so is a constant strictly greater than zero (and independent of the size of the network) if the initial amount of entanglement is above a certain critical value. Quantum mechanics offer here the possibility to change the structure of the network without need to establish new, "physical" channels. By a proper local transformation of the network, the critical entanglement can be decreased and the probability increased. We apply this transformation to complex network models with arbitrary degree distribution. In the case of a noisy network of mixed states, we see that for some classes of states, the same approach of entanglement percolation can be used. For general mixed states, we consider a limited-path-length entanglement percolation constrained by the amount of noise in the connections. We see how complex networks still offer a great advantage in the probability of connecting two nodes. In the second part, we move to the multipartite scenario. We study the creation and distribution of graph states with a structure that mimic the underlying communication network. In this case, we use an arbitrary complex network of noisy channels, and consider that operations and measurements are also noisy. We propose an efficient scheme to distribute and purify small subgraphs, which are then merged to reproduce the desired state. We compare this approach with two bipartite protocols that rely on a central station and full knowledge of the network structure. We show that the fidelity of the generated graphs can be written as the partition function of a classical disordered spin system (a spin glass), and its decay rate is the analog of the free energy. Applying the three protocols to a one-dimensional network and to complex networks, we see that they are all comparable, and in some cases the proposed subgraph protocol, which needs only local information of the network, performs even better.
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Salzwedel, Kay A. "Data distribution algorithms for storage networks." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972387013.
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Johnsen, Lotte. "Content Distribution in Ad Hoc Networks." Thesis, Norwegian University of Science and Technology, Department of Telematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9467.
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Multicast is used to send data to many receivers simultaneously. Multicast protocols developed for wired networks are not suitable for a Mobile Ad Hoc Network (MANET), mainly because the mobile nodes create a changing topology, and the capacity of the nodes and the links are low compared to a wired network. Hence, it is a challenge to distribute information in an Ad Hoc network. A goal for this Masters thesis work has been to investigate content distribution in mobile ad hoc networks to find possible ways to reduce necessary volume of distribution data. Scaling according to available bandwidth and alternative distribution methods to multicast has been investigated. A test architecture consisting of different components useful for content distribution has been configured and tested. Essential components have been: Multicast OLSR (MOLSR); a multicast plugin for the MANET protocol Optimized Link State Routing Protocol (OLSR), to forward multicast data File Delivery over Unidirectional Transport (FLUTE); a protocol that supports sending multicast data in several layers Linux Fedora Core 5 operating system including IEEE 802.11b Wireless Local Area Network (WLAN) adapters A topology emulator to simulate different topologies The first tests were performed using three nodes. Different bit rates and packet sizes were tested to find the best throughput. After adding two more nodes to the network it became clear that the multicast forwarding did not work properly. Many of the first tests have thus given misleading results. After finding an explanation to the multicast forwarding fault, a modification to the test architecture was done; use an older version of Linux Fedora Core. The new test results then showed that it is possible to forward multicast data using FLUTE on a MANET. As expected, the nodes receive a larger amount of the file sent as the number of hops is decreased; up to 100 percent after one hop, whereas up to 80 percent after four hops. Also, test results showed that low data rates give better throughput than high rates. The best throughput was given after resending the FLUTE session several times. The performance of ad hoc networks is less trustworthy than wired / fixed networks. The amount received varies from 0 to 100 percent. The testing of layering using FLUTE did not give any improvements. However, layered content was not available, so all the channels had the same content. Suggestions to possible ways to provide layered content are described. The concept of layering is still interesting for MANETs since it provides the ability for nodes with low capacity to receive less content than nodes with high capacity in a relatively simple way. Further tests are needed to see the results using layered content. When implementations of codec frameworks become more available, these may be great for scaling in ad hoc networks.
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Sert, Caglayan. "Booster Disinfection In Water Distribution Networks." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610755/index.pdf.
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Disinfection of the municipal water systems is mostly achieved by means of chlorine
addition at water treatment plants known as sources. Thus, there should be an adequate
chlorine concentration at the source for an effective disinfection throughout the system
by considering upper and lower limits of disinfectant. However, since the disinfectants
are reactive and decays through the system, chlorine added at the source may not
be enough to maintain desired disinfectant residuals which may lead to water quality
problems in the water distribution system. Moreover, the disinfectants such as chlorine
has also an effect to be carcinogen due to formation of disinfectant by-products. Thus,
the system should balance the amount of disinfectant supplied while minimizing the
health risk. In such a case, it is recommended that one or more booster disinfection
stations can be located throughout the system. Such a method can provide more uniform
distribution of the chlorine concentration while reducing the amount of the disinfectant
used. In this thesis, optimum scheduling, and injection rates of the booster disinfection
stations have been searched. The objective is to minimize the injected mass dosage
rate subjected to the provision of adequate and more uniform residual concentration in
the network. Determination of variable network hydraulics and chlorine concentrations
is held out by EPANET network simulation sofware. A C++ code was developed to
interface with EPANET by means of the EPANET Programmer's Toolkit for linear optimization of the disinfectant mass dosage rate applied to the network.
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Kathiravelu, Thabotharan. "Towards content distribution in opportunistic networks." Licentiate thesis, Uppsala universitet, Avdelningen för datorteknik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85837.
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Opportunistic networking is a new communication paradigm. Content Distribution in opportunistic networks is challenging due to intermittent connectivity, short connection durations and a highly dynamic topology. Research is needed to develop new applications and protocols that can distribute content in opportunistic networks. This thesis explores and evaluates approaches to developing mobile P2P systems for content distribution, focusing mainly on the problem of modeling device contacts. Contact duration and patterns of connections influence routing and forwarding strategies. To model device contacts we need to capture the characteristics of the network and be able to model its behavior. Connectivity models capture the aggregated network behavior by modeling the social connectedness of the network. A model of inter-device relationships can be constructed using parameters are extracted from connectivity traces collected in the field using real devices. These traces represent how connectivity might look in an opportunistic network. Altering and fine tuning these parameters enables us to change the stochastic behavior of the network and study the behavior of applications and protocols. Another approach is mobility modeling. There are two major drawbacks to using mobility models. First, in ad hoc networks traces have been collected which estimate the connectivity of the network. Typically traces are then used to model node mobility which in turn generates nodal connectivity during a simulation. This is a wasteful process and as the network size grows it becomes a tedious job. Second, the inter-contact time distribution observed in traces differs greatly from what is generated by popular mobility models. We have developed a connectivity model to generate synthetic device contact traces for opportunistic networks. We present the preliminary validation results from a comparative study of synthetic traces and traces collected in the field.
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Kwan, Tin-man Tony. "Scalable content distribution in overlay networks." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B3847900X.
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Apaydin, Oncu. "Automated Calibration Of Water Distribution Networks." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615692/index.pdf.
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Water distribution network models are widely used for various purposes such as long-range planning, design, operation and water quality management. Before these models are used for a specific study, they should be calibrated by adjusting model parameters such as pipe roughness values and nodal demands so that models can yield compatible results with site observations (basically, pressure readings). Many methods have been developed to calibrate water distribution networks. In this study, Darwin Calibrator, a computer software that uses genetic algorithm, is used to calibrate N8.3 pressure zone model of Ankara water distribution networkin this case study the network is calibrated on the basis of roughness parameter, Hazen Williams coefficient for the sake of simplicity. It is understood that there are various parameters that contribute to the uncertainties in water distribution network modelling and the calibration process. Besides, computer software&rsquo
s are valuable tools to solve water distribution network problems and to calibrate network models in an accurate and fast way using automated calibration technique. Furthermore, there are many important aspects that should be considered during automated calibration such as pipe roughness grouping. In this study, influence of flow velocity on pipe roughness grouping is examined. Roughness coefficients of pipes have been estimated in the range of 70-140.
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Chen, Ruiming. "Analysis of modern power distribution networks." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66944.
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Analysis and proper design of power distribution networks (PDNs) are critical steps in developing modern electronic systems. Parallel-plate structures with vias are the core components of PDN configuration at any scale of system implementation from chip to package and printed circuit board. Voltage fluctuations induced by vias with carrying time-varying currents are interpreted as power/ground noise. In this thesis, this type of noise is quantified by two fast prediction methods, i.e. using radial transmission line theory and resonant cavity analysis. A number PDN structures containing single or multiple parallel-plates and vias are simulated using the developed analytical models. These models are portable to the commercial circuit simulators, provide a fast means of PDN analysis and enable global system simulations. Suppression of power/ground noise by using discrete decoupling capacitors and differential signalling is investigated using the developed models. The validity of the models is tested against full-wave simulations and prototype measurements. Improvement of power integrity is also studied by using a uniplanar EBG structure in a parallel-plate stack-up. The main challenge in employing EBG structures in compact low frequency designs is the relatively large footprint of the EBG unit cell. This thesis reviews two techniques for miniaturization of a uniplanar EBG and demonstrates their efficacy through full-wave simulations.L'analyse et la conception appropriée du réseau de distribution d'énergie (RDE) sont des étapes critiques lors du développement de systèmes électoniques modernes. La composante principale d'un RDE est une structure de plaques parallèles avec vias, et ce à toutes les étapes de l'implémentation, du désign circuit à la carte imprimée. Les fluctuations du voltage induites par le courant variable qui transite par les vias sont typiquement interprétées comme du bruit sur la source de tension ou la mise à la terre. Dans la présente thèse, ce type de bruit est quantifié à l'aide de deux méthodes rapides de prédiction. Celles-ci sont la théorie radiale des lignes de transmissions ainsi que l'analyse des cavités résonnantes. Plusieurs structures RDE contenant une ou plusieurs plaques parallèles combinées à des vias sont simulées à l'aide des modèles analytiques présentés. Ces modèles sont facilement transférables vers des simulateurs de circuits commerciaux, ce qui fournit un moyen rapide d'effectuer l'analyse du RDE dans une simulation globale. Nous analysons également la suppression de bruit de source/mise à la terre effectuée à l'aide de condensateurs discrets de découplage ou à l'aide de signalement différentiel. Les modèles sont validés par comparaison avec des simulations à onde complète et des mesures sur prototype. Nous étudions les améliorations à l'intégrité de la source de puissance à l'aide de structure EBG dans un empilage de plaques parallèles. Le défi principal relié à l'emploi de structures EBG dans un désign compact et basse fréquence est dû à la grande taille des unités EBG. Nous passons en revue deux techniques pour miniaturiser un EBG uniplanaire et démontrons leur efficacité à l'aide de simulation à onde complète.
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Brooks, Piete. "Distribution of functions in computer networks." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335601.
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Sansawatt, Thipnatee Punim. "Adaptive control for active distribution networks." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6268.
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Rise of the global environmental awareness and climate change impacts caused by greenhouse gases emissions brings about a revolution in the power and energy industries to reduce fossil fuels and promote low-carbon and renewable distributed generation (DG). The new dimensions, mainly encouraged by the governments’ legislative targets and incentives, have allowed the development of DG worldwide. In the U.K., renewable DG especially wind is being connected on distribution networks and ranges widely in scales. Despite the growing number of potential DG sites, the surplus generation present on the passive networks can lead to some technical problems. In particular, rural networks where wind farms exist are prone to voltage rise and line thermal constraints. In order to accommodate new DG and ensure security of supply and network reliability, active management to mitigate these issues are required. In addition, the duties to provide cost-effective DG connections at avoided expensive investment incurred from conventional solutions, e.g., reinforcement and maintain robust network are a major challenge for Distribution Network Operators (DNOs). This thesis endeavours to develop an adaptive control scheme that provides local and real-time management against voltage variations and line capacity overload at the point of wind connections on rural distribution networks. Taking into account maximising power exports and providing an economically-viable control scheme, the wind turbine’s capability, comprising reactive power control and active power curtailment, is used. Whilst the thesis concentrates on the decentralised control applying several different algorithms, in addition, semi-coordinated and centralised approaches that adopt on-load tap changing transformers’ regulation and Optimal Power Flow tool are developed. Comparisons of these approaches based upon measures, i.e., economics, DG penetration and performance are determined. As an outcome, the developed scheme can enable growing integration of renewable DG on distribution networks and can be seen as an interim solution for the DNOs towards Smart Distribution Networks.
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Kwan, Tin-man Tony, and 關天文. "Scalable content distribution in overlay networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3847900X.
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Ma, Yuning. "Statistical modelling of rural distribution networks." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269157.
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Wright, Robert John. "Water distribution networks with dynamic topology." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/58191.
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The subdivision of water distribution networks (WDN) into zones, known as district metered areas (DMAs), is a popular approach to leakage management used by water companies. The DMAs are formed by permanently closing isolation valves at the boundaries of each zone (known as boundary valves). By forming discrete zones in the WDN, leakage estimates can be made at night when demand is low, which is used to prioritise pipe repair and replacement programmes. However, the permanent closure of boundary valves has also caused several disadvantages, including reduced network resilience to failure, sub-optimal pressure management, and water quality problems. This thesis introduces a novel approach to the operational management of WDNs, where DMAs are dynamically aggregated for improved network resilience, pressure management and water quality, and segregated for leakage monitoring at night. This is facilitated by replacing closed boundary valves with self-powered, remote control valves (dynamic boundary valves). The operation of a dynamic topology can therefore successfully eliminate the disadvantages of conventional DMAs, whilst retaining or improving their success in leakage monitoring. The investigation is carried out both analytically and experimentally on a real, operational UK network supplying approximately 8,000 properties in order to establish the benefits and challenges of the proposed approach. An extensive review of the current and emerging forms of pressure and DMA management from around the world is carried out. A case study using a real large scale network (3,148km of pipeline) demonstrates the current state of DMAs and their conformity to DMA design guidelines, and identifies how a dynamic DMA topology can improve network performance. A novel resilience index (the Reserve Capacity) is then used in the design of the dynamic DMA topology in the experimental programme. The analytical and experimental investigation has demonstrated a 27% reduction in leakage using a dynamic DMA topology over the most common approach to pressure management, and strong improvements in network resilience to failure where 1,400 customers maintained a supply during a real, major burst incident that would otherwise have been disconnected. In order to actuate near optimal control in the experimental programme, a novel optimisation algorithm based on sequential convex programming (SCP) is proposed for the control of valves. The SCP method takes advantage of computationally efficient solvers that facilitate prompt and reliable convergence. The algorithm also includes the development of a novel, convex valve model that can be integrated into efficient null space algorithms. In order to actuate the control, a novel approach for valve control in DMAs with dynamic topology is proposed, where time varying flow modulation curves are used based on the dynamic connectivity of DMAs.
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Powell, James Charlton. "Modelling chlorine in water distribution networks." Thesis, University of Birmingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682176.
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Machell, John. "Water quality modelling in distribution networks." Thesis, University of Sheffield, 2004. http://etheses.whiterose.ac.uk/14849/.
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The thesis is a treatise of the quantity and quality aspects of potable water in distribution systems. The privatisation of the UK Water Industry in 1989 has seen the requirement for the Water Companies in England and Wales to be responsible for the delivery of good quality water that meets the demand of all consumers. In respect of the quantity of supply, there have been many previous studies that have examined the hydraulic performance of distribution systems and there are now many proprietary mathematical models that have been successfully used in this study. However, in respect of water quality the literature review has highlighted that the modelling approach is not so well advanced, as water quality is a function of many concepts, processes and parameters that include the source and age of water, the condition and deterioration of the assets in the system, the microbiological, chemical and physical processes and the network hydraulic performance, including pressure transients. These processes are highly interactive and complex. In an attempt to better understand these processes a programme of research has been completed that has involved a field evaluation of the performance of a live system, including the development of instrumentation to continually measure water quality, and the development of a mathematical model to describe the processes associated with the age of water and the propagation of conservative and non-conservative substances. An initial attempt has also been made to develop a micro-biological model and a sediment transport model. New original concepts developed by the author include age, biological and diagnostic models that may be used to identify the source of any incident (hydraulic or pollution) and the application of the model in near real time.
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Silva, José Miguel Costa. "Content distribution in OTT wireless networks." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/22733.
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Mestrado em Engenharia Electrónica e de TelecomunicaçõesIn developed countries, the Internet is increasingly considered an essential and integral part of people's lives. The need to be \online", share and access content are frequent routines in people's daily lives, making the Internet one of the most complex systems in operation. Most traditional communications (telephone, radio and television) are being remodelled or rede ned by the Internet, giving rise to new services such as Voice over Internet Protocol (VoIP) and Internet Protocol Television (IPTV). Books, newspapers and other types of printed publications are also adapting to the web technology or have been redesigned for blogs and feeds. Massi cation of the Internet and the constant increase in bandwidth o ered to the consumers have created excellent conditions for services such as OTT. OTT Services refer to the delivery of audio, video and other data over the Internet without the control of network operators. Although the OTT delivery presents an attractive solution (and pro table, looking at the fast growing services such as YouTube, Skype and Net ix, for example), it su ers from some limitations. It is necessary to maintain high levels of Quality-of-Experience (QoE) to continue to attract customers. In order to do this, a content distribution network is fundamental to adapt to the speed with which the contents are required and quickly discarded and that can accommodate all the tra c. This dissertation focuses on the distribution of OTT contents in wireless networks, in order to address the lack of research work in this area. A solution is proposed that can be integrated by the network equipment so that it is able to predict what kind of content consumers connected (or nearby) may request and put it in memory before being requested, improving consumers' perception of the service. Given the lack of information in the literature on management and control of proxy caches for embedded systems, the rst step was to test and evaluate two di erent cache algorithms: Nginx and Squid. The results show that there is a trade-o between cache performance and speed in processing the requests, with Nginx delivering better performance but worse response times. It was also found that cache size does not always determine a signi cant improvement in results. Sometimes keeping just the most popular content cached is enough. Afterwards, two algorithms for predicting prefetching contents in mobility scenarios were proposed and tested, given the characteristics of the wireless networks, where it was possible to observe very signi cant performance improvements, demonstrating that there is a possibility for an investment in this area, although this implies an increase in the processing capacity and power consumption of the network equipment.
Nos países desenvolvidos, cada vez mais a Internet é considerada um bem essencial. A necessidade de estar \online", partilhar e aceder a conteúdos são rotinas frequentes no dia-a-dia das pessoas, tornando assim a Internet num dos sistemas mais complexos em operação. A maioria das comunicações tradicionais (telefone, radio e televisão) estão a ser remodeladas ou redefinidas pela Internet, dando origem a novos serviços, como o protocolo de Internet por voz (VoIP) e o protocolo de Internet de televisão (IPTV). Livros, jornais e outro tipo de publicações impressas estão também a adaptar-se á tecnologia web ou têm sido reformuladas para blogs e feeds. A massificação da Internet e o aumento constante das larguras de banda oferecidas aos consumidores criaram condiçoes excelentes para serviços multimedia do tipo Over-The-Top (OTT). Serviços OTT referem se á entrega de áudio, vídeo e outros via Internet sem usar o controlo dos operadores de rede. Apesar da entrega OTT apresentar uma proposta atractiva (e lucrativa, olhando para o rápido crescimento de servicos como o YouTube, Skype e Net ix, por exemplo) esta sofre de algumas limitações. É necessario manter n veis elevados de Qualidade-de-Experi^encia (QoE) para continuar a atrair clientes. Para isso é fundamental uma rede de distribuição de conteúdos capaz de se adaptar á rapidez com que os conteúdos são requeridos e rapidamente descartados e que consiga albergar todo o tráfego. Esta dissertação foca-se na distribuição de conteúdos OTT nas redes sem fios, por forma a endereçar a falta de trabalhos de investigação nesta área. É proposta uma solução que visa poder ser integrada pelos equipamentos de rede para, desta forma, estes serem capazes de prever que tipo de conteúdo os consumidores conectados (ou nas proximidades) possam vir a solicitar e coloca-lo em memoria antes de ser pedido, melhorando a percepção com que os consumidores recebem o mesmo. Dada a falta de informação na literatura sobre gestão e controlo de proxy caches para sistemas embutidos, o primeiro passo foi testar e avaliar dois algoritmos de cache diferentes: Nginx e Squid. Os resultados mostram que existe um compromisso entre o desempenho de cache e velocidade no processamento dos pedidos, apresentando o Nginx um melhor desempenho mas piores tempos nas respostas aos pedidos. Foi também verificado que o tamanho da cache nem sempre determina um melhoramento significativo nos resultados. Ás vezes, manter apenas o conteúdo mais popular em cache é suficiente. De seguida, foram propostos e testados dois algoritmos de previsão de conteúdos (prefetching ) em cenários de mobilidade, dada as características das redes sem fios, onde foi possível observar melhorias de desempenho muito significativas, demonstrando que existe a possibilidade de ser viável um investimento nesta área, embora isto implique um aumento na capacidade de processamento/ consumo de energia dos equipamentos de rede.
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Voruganti, Anupama. "Key distribution for wireless sensor networks." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-03052008-130408.
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Lopez-Ibanez, Manuel. "Operational optimisation of water distribution networks." Thesis, Edinburgh Napier University, 2009. http://researchrepository.napier.ac.uk/Output/3044.
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Water distribution networks are a fundamental part of any modern city and their daily operations constitute a significant expenditure in terms of energy and maintenance costs. Careful scheduling of pump operations may lead to significant energy savings and prevent wear and tear. By means of computer simulation, an optimal schedule of pumps can be found by an optimisation algorithm. The subject of this thesis is the study of pump scheduling as an optimisation problem. New representations of pump schedules are investigated for restricting the number of potential schedules. Recombination and mutation operators are proposed, in order to use the new representations in evolutionary algorithms. These new representations are empirically compared to traditional representations using different network instances, one of them being a large and complex network from UK. By means of the new representations, the evolutionary algorithm developed during this thesis finds new best-known solutions for both networks. Pump scheduling as the multi-objective problem of minimising energy and maintenance costs in terms of Pareto optimality is also investigated in this thesis. Two alternative surrogate measures of maintenance cost are considered: the minimisation of the number of pump switches and the maximisation of the shortest idle time. A single run of the multi-objective evolutionary algorithm obtains pump schedules with lower electrical cost and lower number of pump switches than those found in the literature. Alternatively, schedules with very long idle times may be found with slightly higher electrical cost. Finally, ant colony optimisation is also adapted to the pump scheduling problem. Both Ant System and Max-Min Ant System are tested. Max-Min Ant System, in particular, outperforms all other algorithms in the large real-world network instance and obtains competitive results in the smallest test network. Computation time is further reduced by parallel simulation of pump schedules.
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Tossani, Fabio <1988>. "Insulation Coordination in Modern Distribution Networks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7296/1/tossani_fabio_tesi.pdf.
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The appropriate analysis of the response of distribution networks against Lightning Electro Magnetic Pulse (LEMP) – originated by nearby strikes – requires the availability of accurate coupling models in order to reproduce the real and complex configuration of distribution systems.
The above models represent a fundamental tool for estimating the number of protective devices and their most appropriate location in order to guarantee a given minimum number of flashovers and outages per year. When dealing with real networks, such an optimization could require huge computational efforts due to the vast number of power components and feeders. This thesis thoroughly analyzes many of the possible engineering simplifications that, without losing accuracy, can be adopted in the statistical evaluation of the lightning performance of distribution networks in order to limit computational times.
Particular attention is devoted to the effect of the ground conductivity on the LEMP and on the line parameters; two new analytical expressions for the evaluation of the inverse Laplace transform of the ground impedance matrix elements of multiconductor overhead lines are derived. The first expression is the inverse Laplace transform of Sunde’s logarithmic formula and is given in two equivalent forms. The second expression is the inverse Laplace transform of Sunde’s general integral expression.
Finally, a procedure able to evaluate the lightning performance of a real medium-voltage distribution network, which includes several lines, transformers and surge protection devices is developed and proposed for the analysis of some real cases. Such a procedure allows inferring the characteristics of the statistical distributions of lightning-originated voltages at any point and phase of the network. The analysis aims at assessing the expected mean time between failures of transformers caused by both direct and indirect lightning strikes.L'analisi della risposta di una rete elettrica di distribuzione a un campo elettromagnetico esterno generato da una scarica atmosferica richiede l'utilizzo di accurati modelli in grado di riprodurre la reale e complessa configurazione della rete. Tali modelli rappresentano uno strumento fondamentale per la stima del numero di dispositivi di protezione ed il loro appropriato collocamento al fine di garantire il numero minimo annuo di “flashovers” e interruzioni. In una rete di distribuzione reale, tale ottimizzazione può richiedere sforzi computazionali proibitivi a causa dell’elevatissimo numero di componenti di potenza e linee presenti. Questa tesi analizza in maniera esaustiva molteplici semplificazioni ingegneristiche adottabili, al fine di ridurre i tempi computazionali, nella valutazione statistica del numero annuo di guasti di una rete di distribuzione. Particolare attenzione è dedicata agli effetti della conducibilità finita del suolo sul campo irradiato dal fulmine e sui parametri delle linee. Nella tesi sono derivate due nuove espressioni analitiche per il calcolo della trasformata di Laplace inversa dell’impedenza del terreno. La prima è la trasformata di Laplace inversa dell’espressione di Sunde logaritmica ed è proposta in due forme equivalenti. La seconda è la trasformata di Laplace inversa della più generale espressione integrale di Sunde. Infine, si è sviluppata una procedura in grado di valutare la “lightning performance” di una rete di distribuzione in media tensione avente configurazione realistica, che comprende “feeder” principali e laterali, pali, cabine secondarie e dispositivi di protezione contro le sovratensioni. La procedura messa a punto, basata sull’applicazione del metodo di Monte Carlo, permette di calcolare l'ampiezza delle tensioni indotte da fulminazione in qualsiasi punto e in ogni fase della rete. L’attività ha riguardato anche la valutazione del tempo medio fra i guasti (MTBF) di ogni trasformatore MT / BT causati da fulminazione indiretta e diretta, parametro di fondamentale rilevanza per l’ente distributore.
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Tossani, Fabio <1988>. "Insulation Coordination in Modern Distribution Networks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7296/.
Full textAbstract:
The appropriate analysis of the response of distribution networks against Lightning Electro Magnetic Pulse (LEMP) – originated by nearby strikes – requires the availability of accurate coupling models in order to reproduce the real and complex configuration of distribution systems.
The above models represent a fundamental tool for estimating the number of protective devices and their most appropriate location in order to guarantee a given minimum number of flashovers and outages per year. When dealing with real networks, such an optimization could require huge computational efforts due to the vast number of power components and feeders. This thesis thoroughly analyzes many of the possible engineering simplifications that, without losing accuracy, can be adopted in the statistical evaluation of the lightning performance of distribution networks in order to limit computational times.
Particular attention is devoted to the effect of the ground conductivity on the LEMP and on the line parameters; two new analytical expressions for the evaluation of the inverse Laplace transform of the ground impedance matrix elements of multiconductor overhead lines are derived. The first expression is the inverse Laplace transform of Sunde’s logarithmic formula and is given in two equivalent forms. The second expression is the inverse Laplace transform of Sunde’s general integral expression.
Finally, a procedure able to evaluate the lightning performance of a real medium-voltage distribution network, which includes several lines, transformers and surge protection devices is developed and proposed for the analysis of some real cases. Such a procedure allows inferring the characteristics of the statistical distributions of lightning-originated voltages at any point and phase of the network. The analysis aims at assessing the expected mean time between failures of transformers caused by both direct and indirect lightning strikes.L'analisi della risposta di una rete elettrica di distribuzione a un campo elettromagnetico esterno generato da una scarica atmosferica richiede l'utilizzo di accurati modelli in grado di riprodurre la reale e complessa configurazione della rete. Tali modelli rappresentano uno strumento fondamentale per la stima del numero di dispositivi di protezione ed il loro appropriato collocamento al fine di garantire il numero minimo annuo di “flashovers” e interruzioni. In una rete di distribuzione reale, tale ottimizzazione può richiedere sforzi computazionali proibitivi a causa dell’elevatissimo numero di componenti di potenza e linee presenti. Questa tesi analizza in maniera esaustiva molteplici semplificazioni ingegneristiche adottabili, al fine di ridurre i tempi computazionali, nella valutazione statistica del numero annuo di guasti di una rete di distribuzione. Particolare attenzione è dedicata agli effetti della conducibilità finita del suolo sul campo irradiato dal fulmine e sui parametri delle linee. Nella tesi sono derivate due nuove espressioni analitiche per il calcolo della trasformata di Laplace inversa dell’impedenza del terreno. La prima è la trasformata di Laplace inversa dell’espressione di Sunde logaritmica ed è proposta in due forme equivalenti. La seconda è la trasformata di Laplace inversa della più generale espressione integrale di Sunde. Infine, si è sviluppata una procedura in grado di valutare la “lightning performance” di una rete di distribuzione in media tensione avente configurazione realistica, che comprende “feeder” principali e laterali, pali, cabine secondarie e dispositivi di protezione contro le sovratensioni. La procedura messa a punto, basata sull’applicazione del metodo di Monte Carlo, permette di calcolare l'ampiezza delle tensioni indotte da fulminazione in qualsiasi punto e in ogni fase della rete. L’attività ha riguardato anche la valutazione del tempo medio fra i guasti (MTBF) di ogni trasformatore MT / BT causati da fulminazione indiretta e diretta, parametro di fondamentale rilevanza per l’ente distributore.
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Gabrys, Bogdan. "Neural network based decision support : modelling and simulation of water distribution networks." Thesis, Nottingham Trent University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387534.
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Zhang, Yan. "Cost reflective network pricing for high voltage and low voltage distribution networks." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558863.
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Nguyen, Thanh Vinh. "Content distribution networks over shared infrastructure a paradigm for future content network deployment /." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060509.094632/index.html.
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Neimane, Viktoria. "On Development Planning of Electricity Distribution Networks." Doctoral thesis, KTH, Electrical Systems, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3253.
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Future development of electric power systems must pursue anumber of different goals. The power system should beeconomically efficient, it should provide reliable energysupply and should not damage the environment. At the same time,operation and development of the system is influenced by avariety of uncertain and random factors. The planner attemptsto find the best strategy from a large number of possiblealternatives. Thus, the complexity of the problems related topower systems planning is mainly caused by presence of multipleobjectives, uncertain information and large number ofvariables. This dissertation is devoted to consideration of themethods for development planning of a certain subsystem, i.e.the distribution network.
The dissertation first tries to formulate the networkplanning problem in general form in terms of Bayesian DecisionTheory. However, the difficulties associated with formulationof the utility functions make it almost impossible to apply theBayesian approach directly. Moreover, when approaching theproblem applying different methods it is important to considerthe concave character of the utility function. Thisconsideration directly leads to the multi-criteria formulationof the problem, since the decision is motivated not only by theexpected value of revenues (or losses), but also by theassociated risks. The conclusion is made that the difficultiescaused by the tremendous complexity of the problem can beovercome either by introducing a number of simplifications,leading to the considerable loss in precision or applyingmethods based on modifications of Monte-Carlo or fuzzyarithmetic and Genetic Algorithms (GA), or Dynamic Programming(DP).
In presence of uncertainty the planner aims at findingrobust and flexible plans to reducethe risk of considerablelosses. Several measures of risk are discussed. It is shownthat measuring risk by regret may lead to risky solutions,therefore an alternative measure - Expected Maximum Value - issuggested. The general future model, called fuzzy-probabilistictree of futures, integrates all classes of uncertain parameters(probabilistic, fuzzy and truly uncertain).
The suggested network planning software incorporates threeefficient applications of GA. The first algorithm searchessimultaneously for the whole set of Pareto optimal solutions.The hybrid GA/DP approach benefits from the global optimizationproperties of GA and local search by DP resulting in originalalgorithm with improved convergence properties. Finally, theStochastic GA can cope with noisy objective functions.
Finally, two real distribution network planning projectsdealing with primary distribution network in the large city andsecondary network in the rural area are studied.
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Sørensen, Svein-Magnus Bergan. "Multimedia Distribution Networks and the Aeetes Project." Thesis, Norwegian University of Science and Technology, Department of Telematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9290.
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This thesis provides an introduction to the field of Multimedia Distribution Networks (MDN) and is written as the first part the Aeetes Project. It compares potential MDN architectures and technologies, and makes a proposal for a suitable IMDN architecture based on it. The thesis defines the concepts of MDN and IMDN, and describes the current state of the art of MDN technologies and implementations. An Internet-based Multimedia Distribution Network (IMDN) is a type of overlay network, comprised of a cluster of servers on the Internet which is used to distribute multimedia content to end-users in a cost-efficient manner with better quality of service compared to regular distribution models. It also makes a comparison of the technology and performance of various existing MDN architectures with focus on their advantages and limitations. Based on this comparison the possible architectures are evaluated and a proposal is made for an Aeetes implementation candidate. The suggested architecture is focused on low cost and simple deployment, and is designed to be used in both academic and commercial settings. It also attempts to be extensible and to allow for simple modifications as it might become the base system upon which a range of further work in the field of Multimedia Distribution Networks is built.
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Alvarez, Perez Manuel Alejandro. "Stochastic Planning of Smart Electricity Distribution Networks." Licentiate thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60778.
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The penetration of intermittent Distributed Generation (DG) brought additional uncertainty to the system operation and planning. To cope with uncertainties the Distribution System Operator (DSO) could implement several strategies. These strategies range from the inclusion of smart technologies which will increment system’s flexibility and resiliency, to improvements in forecasting, modeling, and regulatory pledge that will facilitate the planning activity. Regardless of the nature of the solutions, they could be collected in a sort of toolbox. The planner will access the toolbox to conform cost effective plans, better able to deal with any uncertainty. The present work will address the problem of distribution system planning under uncertainties, considering smart solutions along with traditional reinforcements, in the short-term lead time up to 3 years ahead. The work will be focused on three aspects that are the cornerstones of this work: • A planning facilitating strategy: Distribution Capacity Contracts (DCCs). • A flexibility enabler technology: Energy Storage. • A binding methodology: Multistage Stochastic Programming. Stochastic dual dynamic programming (SDDP). Under the present directive of the European Parliament concerning common rules for the internal market in electricity, distribution companies are not allowed to own DG but entitled to include it as a planning option to differ investment in traditional grid reinforcements. An evaluation of the regulatory context will lead this work to consider DCCs as a planning alternative available in the toolbox. The impact of this type of contract on the remuneration of the DG owner will be assessed in order to provide insight on its willingness to participate. The DCCs might aid the DSO to defer grid i ii investments during planning stages and to control the network flows during operation. Given that storage solutions help to match in time production from intermittent sources with load consumption, they will play a major role in dealing with uncertainties. A generic storage model (GSM) based on a future cost piecewise approximation will be developed. This model inspired by hydro-reservoirs will help assessing the impact of storage in planning decisions. This model will be tested by implementing it in short-term hydro scheduling and unit commitment studies. To trace a path towards the future of this research work, a discussion on the planning problem formulation, under consideration of the lead time, the expansion options, the smart strategies, and the regulatory framework will be presented. Special focus will be given to multistage stochastic programming methods and in particular to the SDDP approach.
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Bayan, Nima. "Harmonic flow analysis in power distribution networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0011/MQ52509.pdf.
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Hassine, Wijden Ben. "Distribution of information in ad hoc networks." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5FBen%5FHassine.pdf.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2007.Thesis Advisor(s): Singh, Gurminder. "September 2007." Description based on title screen as viewed on October 22, 2007. Includes bibliographical references (p. 79-85). Also available in print.
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Zeeuwen, Kyle. "Optimizing re-evaluation of malware distribution networks." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/37958.
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The retrieval and analysis of malicious content is an essential task for security researchers. Security labs use automated HTTP clients known as client honeypots to visit hundreds of thousands of suspicious URLs daily. The dynamic nature of malware distribution networks necessitate periodic re-evaluation of a subset of the confirmed malicious sites, which introduces two problems: 1) the number of URLs requiring re-evaluation exhaust available resources, and 2) repeated evaluation exposes the system to adversarial blacklisting, which affects the accuracy of the content collected. To address these problems, I propose optimizations to the re-evaluation logic that reduce the number of re-evaluations while maintaining a constant sample discovery rate during URLs re-evaluation.
I study these problems in two adversarial scenarios: 1) monitoring malware repositories where no provenance is available, and 2) monitoring Fake Anti-Virus (AV) distribution networks. I perform a study of the adversary by repeatedly content from the distribution networks. This reveals trends in the update patterns and lifetimes of the distribution sites and malicious executables. Using these observations I propose optimizations to reduce the amount of re-evaluations necessary to maintain a high malicious sample discovery rate.
In the first scenario the proposed techniques, when evaluated versus a fixed interval scheduler, are shown to reduce the number of re-evaluations by 80-93% (assuming a re-evaluation interval of 1 hour to 1 day) with a corresponding impact on sample discovery rate of only 2-7% percent. In the second scenario, optimizations proposed are shown to reduce fetch volume by orders of magnitude and, more importantly, reduce the likelihood of blacklisting.
During direct evaluation of malware repositories I observe multiple instances of blacklisting, but on the whole, less than 1% of the repositories studied show evidence of blacklisting. Fake AV distribution networks actively blacklist IPs; I encountered repeated occurrences of IP blacklisting while monitoring Fake AV distribution networks.
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Papadopoulos, Panagiotis. "Integration of electric vehicles into distribution networks." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/19539/.
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The objectives of this research were to investigate the impact of electric vehicle battery charging on grid demand at a national level and on the steady state parameters of distribution networks. An agent-based control system that coordinates the battery charging of electric vehicles according to electric vehicle owner preferences, distribution network technical limits and electricity prices was designed and developed and its operation was tested experimentally. The impact on grid demand peak increases at the national systems of Great Britain and Spain was evaluated using low and high electric vehicle uptake levels of 7% and 48.5% of the car fleet for the year 2030 with a deterministic method. It was found that a low uptake will not raise significantly the grid demand peaks in both countries under investigation. However, a high uptake will raise significantly the grid demand peaks. The impact from residential electric vehicle battery charging on steady state voltages, power line losses, transformers’ and cables’ loadings of distribution networks was evaluated using a deterministic and a probabilistic method. It was found that low and medium uptake levels of electric vehicles equivalent to 12.5% and 33% per residential area of 384 customers in 2030, can be safely accommodated by reinforcing the distribution network. A combination of reinforcements, installation of microgenerators and control of electric vehicle battery charging will be required to accommodate safely a high uptake of 71% with regards to the constraints studied. An agent-based control system that coordinates the battery charging of electric vehicles was designed and developed. Search techniques and neural networks were used for the decision making processes. The ability of the agent-based control system to operate successfully in both normal and abnormal conditions for the electrical network was proved with experimental validation in the laboratory of Tecnalia research institute in Spain.
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吳學章 and Hok-cheong Ng. "Information technology distribution networks in Mainland China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31269126.
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Choudhary, P. A. "State estimation applied to gas distribution networks." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378007.
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The need to make more efficient use of energy resources by improved methods of control, the deferment of expensive pipework reinforcement or replacement and the requirement to accommodate different loading patterns on sections of the gas network have made the requirement for effective feedback control essential. Gas distribution systems are large and complex and a major problem in applying conventional feedback techniques is the cost and reliability of transmitting the data necessary for automatic control. In order to overcome these difficulties, state estimation techniques have been investigated as a means of providing information about a distribution system from a minimum number of measurement points. The theoretical background to the study is reviewed including the modelling technique and the results of experimental work which has been performed on a distribution network in order to verify the techniques developed are presented. The results show that state estimation techniques have considerable potential for this type of application.
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Eyisi, Chiebuka. "Load Estimation for Electric Power Distribution Networks." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5935.
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In electric power distribution systems, the major determinant in electricity supply strategy is the quantity of demand. Customers need to be accurately represented using updated nodal load information as a requirement for efficient control and operation of the distribution network. In Distribution Load Estimation (DLE), two major categories of data are utilized: historical data and direct real-time measured data. In this thesis, a comprehensive survey on the state-of-the-art methods for estimating loads in distribution networks is presented. Then, a novel method for representing historical data in the form of Representative Load Curves (RLCs) for use in real-time DLE is also described. Adaptive Neuro-Fuzzy Inference Systems (ANFIS) is used in this regard to determine RLCs. An RLC is a curve that represents the behavior of the load during a specified time span; typically daily, weekly or monthly based on historical data. Although RLCs provide insight about the variation of load, it is not accurate enough for estimating real-time load. This therefore, should be used along with real-time measurements to estimate the load more accurately. It is notable that more accurate RLCs lead to better real-time load estimation in distribution networks.
This thesis addresses the need to obtain accurate RLCs to assist in the decision-making process pertaining to Radial Distribution Networks (RDNs).This thesis proposes a method based on Adaptive Neuro-Fuzzy Inference Systems (ANFIS) architecture to estimate the RLCs for Distribution Networks. The performance of the method is demonstrated and simulated, on a test 11kV Radial Distribution Network using the MATLAB software. The Mean Absolute Percent Error (MAPE) criterion is used to justify the accuracy of the RLCs.M.S.E.E.
Masters
Electrical Engineering and Computing
Engineering and Computer Science
Electrical Engineering
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Daka, J. S. J. "Broadcast file distribution on packet satellite networks." Thesis, University of Essex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235266.
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Somani, Paritosh 1979. "Real time inventory tracking in distribution networks." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86736.
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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (leaves 72-73).
by Paritosh Somani.
M.Eng.and S.B.
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Campillo, Javier. "From Passive to Active Electric Distribution Networks." Doctoral thesis, Mälardalens högskola, Framtidens energi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-31592.
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Large penetration of distributed generation from variable renewable energy sources, increased consumption flexibility on the demand side and the electrification of transportation pose great challenges to existing and future electric distribution networks. This thesis studies the roles of several actors involved in electric distribution systems through electricity consumption data analysis and simulation models. Results show that real-time electricity pricing adoption in the residential sector offers economic benefits for end consumers. This occurs even without the adoption of demand-side management strategies, while real-time pricing also brings new opportunities for increasing consumption flexibility. This flexibility will play a critical role in the electrification of transportation, where scheduled charging will be required to allow large penetration of EVs without compromising the network's reliability and to minimize upgrades on the existing grid. All these issues add significant complexity to the existing infrastructure and conventional passive components are no longer sufficient to guarantee safe and reliable network operation. Active distribution networks are therefore required, and consequently robust and flexible modelling and simulation computational tools are needed for their optimal design and control. The modelling approach presented in this thesis offers a viable solution by using an equation-based object-oriented language that allows developing open source network component models that can be shared and used unambiguously across different simulation environments.
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Cao, Jianing. "Operational voltage control of future distribution networks." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23511.
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Voltages in distribution networks are subject to variations primarily due to varying demand and the intermittent nature of growing renewable generation. Conventionally voltages are regulated only at certain locations such as distribution substations with some fixed settings for control equipment such as voltage targets or tap changers of under-load tap changing (ULTC) transformers and switching status of shunt capacitors. These settings are normally determined by operators in control rooms and are changed on the condition that power supply cannot be adequately delivered. A fixed constant setting for the controllable devices may not guarantee secured voltage profiles for all load centres at all times during the course of a day and may lead to frequent operations due to fluctuations in generation and demand profiles, which will eventually lead to wear on the control equipment. This thesis investigates the operational control of voltages on distribution networks and proposes a control strategy that manages voltage control devices from an operational planning perspective in order to maintain a desired level of voltage security by applying the most cost-effective control actions. The proposed methodology integrates power system sensitivity analysis and an artificial intelligence (AI) planning approach to schedule voltage control actions for a given electrical system across a specific planning time period based on known generation and demand profiles. The concept of a failsafe mode is incorporated into the proposed control strategy to deal with the potential loss of data communication or ultimate failure of the planned solutions. A typical radial distribution network model was studied under a range of scenarios and the simulation results demonstrated that the proposed methodology was capable of automatically planning control settings for ULTC transformers and MSCs to maintain requisite voltage limits and outperformed the conventional methods by eliminating the number of voltage violations and also reducing the number of control operations. The flexibility of the proposed methodology allows it to be integrated to the existing software platforms used by some of the UK distribution network operators (DNOs).
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Antoniou, Dimitris. "Transition from AC to DC distribution networks." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/transition-from-ac-to-dc-distribution-networks(4835157b-7b31-434a-ab1c-3e9ca0a71318).html.
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Maximising the capacity of the existing AC distribution network infrastructure by conversion to DC holds significant advantages. In particular it may provide a greater flow of electrical energy within urban areas, allowing a lower investment cost for adoption of electrical vehicles and domestic heating. Integration with Smart Grid applications will require maintained levels of reliability, and improved efficiency and flexibility. The transition of the cable infrastructure from the legacy LVAC (low voltage alternating current) system to LVDC (low voltage direct current) is considered in this work. In particular this thesis investigates the limitations of DC supplied through the existing distribution network without major re- construction, and proposes optimal configurations that could be adopted in a smart-DC distribution network. The implications for power flow in the network are considered with regards to existing cable limitations. The operation of legacy LVAC distribution cables under DC is considered in this work. The electric field distribution in cable insulation under DC voltage is governed by the electrical conductivity of the material unlike the AC case where it is dependent on the permittivity of the materials. Temperature, water ingress and chemical ageing can influence the electrical properties of the insulation. The first major contribution to literature from this work is the demonstration that moisture penetration is the most influential factor in LV cable failure. Local elevated stress further alters the insulation properties leading to a thermal runaway and cable failure. LV cable insulation structures were tested experimentally and by the use of Finite Element Analysis simulations for both AC and DC. DC proved to be the superior option in all tests. Moisture and generated heat cause higher losses under AC due to the impedance being dependent on capacitance which is not as heavily affected as the resistance. The second major contribution of this work is the demonstration that LVDC is a very attractive alternative for future distribution networks. Total system capacity can increase by at least a factor of 1.41. It was shown that LVDC lowers total system losses which in turn lead to a prolonged plant lifespan. A decrease in losses guarantees a more reliable, robust and future proof network. Power electronics will inevitably drop in price allowing for such a transition to take place which will assure the supply of electrical energy for future needs. Rewiring will be inevitable even under AC, following the increase in demand which will require the uprating of the existing lines. A phased implementation will allow for a smooth transition to a LVDC distribution network.