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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Projeto de transdutor de corrente elétrica para alta tensão com nova abordagem de detecção magnetostritiva e sensoriamento óptico, utilizando Terfenol-D e grade de Bragg em fibra óptica / High voltage electric current transducer project, with innovative approach for magnetostrictive modulation and optical sensing using Terfenol-D and fiber Bragg gratings

Cremonezi, Alcides Oliveira 08 December 2011 (has links)
Orientador: Elnatan Chagas Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-19T01:27:01Z (GMT). No. of bitstreams: 1 Cremonezi_AlcidesOliveira_M.pdf: 4474466 bytes, checksum: 5a33efaeb2ab330c00861ab393b6c732 (MD5) Previous issue date: 2011 / Resumo: Os sensores a fibra óptica são imunes à interferência eletromagnética (EMI), eles são normalmente encontrados em ambientes eletricamente ruidosos, especialmente em linhas de transmissão de alta voltagem. Essa é a característica principal que faz desse tipo de sensores ideais para empresas de Energia Elétrica. Esse trabalho apresenta uma nova abordagem, de precisão moderada, robusta e de baixo custo, para a fabricação de um transdutor de corrente elétrica para alta tensão, com detecção magnetostritiva utilizando material inteligente, Terfenol-D, e sensoriamento óptico através de grade de Bragg em fibra óptica (FBG). O núcleo magnético foi desenvolvido em formato toroidal e construído utilizando usinagem através de eletro-erosão, o que resultou em uma peça única com projeto mecânico robusto. Aplicando compressão mecânica ao sensor toroidal e fazendo sua resposta ficar muito próxima a uma função quadrática, foi possível calcular o valor RMS da corrente diretamente do sinal de saída do sensor, e com isso, eliminar qualquer polarização magnética DC utilizada em técnicas anteriores reportadas na literatura. Foi utilizada com sucesso, uma nova técnica de circuito eletrônico de interrogação que permite a medida de sinais AC e mantém o ponto de operação DC da FBG. Resultados experimentais medidos com o transdutor óptico desenvolvido mostraram que entre correntes de aproximadamente 200 a 900A o erro observado foi de apenas 1,2% e sua dependência com a temperatura dentro de um range de 25 a 450C mostrou erro máximo de 2%. O sistema desenvolvido apresenta rápida resposta a transiente e precisa de somente 34ms para alcançar o estado estacionário quando submetido a um aumento de 150% da corrente nele medida. Os resultados mostram que o projeto sugerido é adequado e muito promissor para a construção comercial de um transdutor óptico de corrente para alta tensão / Abstract: Optical sensors are passives and immunes to electromagnetic interferences (EMI), they are well suited for applications in electrically noisy environments, especially in high voltages transmission lines. This is the main characteristic that makes them ideal to electrical energy companies. A new approach to the fabrication of, moderated precision, robust and low-cost fiber Bragg gratings (FBG) optical current transducers using a Terfenol-D magnetostrictive smart material is presented. Electro-erosion was used to manufacture a magnetic core in a toroidal shape which resulted in a single piece robust mechanical design. By applying mechanical compression to the toroidal sensor and making its response very close to a quadratic function, it is possible to calculate the RMS value of the current directly from the output of the sensor and eliminate the DC biasing magnetic field used in previous literature reported techniques. A new electronic interrogation circuit technique which allows the measurement of AC signals and keeps the DC operation point of the FBG was implemented and successfully used in the prototype. Experimental results measured in the developed optical current transducer showed that an error of 1.2% was achieved for currents over approximately the 200 to 900A range and its temperature dependence in a range of 25 to 450C has showed a maximum error of 2%. The developed system presents a fast transient response, and needs only 34ms to reach the steady state after a 150% amplitude step increase is applied to current being measured. The results shows that the developed project is feasible and also very promisor to be considered on commercial applications / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica
72

Molecular relaxation dynamics of Anthracene cations studied in an electrostatic storage ring / Dynamique de relaxation de cations d'Anthracène étudiée dans un anneau de stockage électrostatique

Ji, Ming Chao 28 April 2015 (has links)
Les molécules hydrocarbures aromatiques polycycliques (HAP) sont à l'heure actuelle considérées comme probablement responsables des bandes d'émission infrarouge non identifiées du milieu interstellaire (MIS). La dynamique de refroidissement des molécules HAP est essentielle pour estimer leur photo-stabilité, leur durée de vie et les distributions de taille dans le MIS. Au cours des dernières années, les expériences s'appuyant sur le stockage électrostatique d'ions moléculaires ou d'agrégats sont devenus des outils puissants pour étudier leur refroidissement dans une large gamme de temps allant de la microseconde à quelques secondes. En général, l'étude des courbes de déclin associées aux processus de dissociation dans le cas des cations ou bien de détachement d'électrons dans le cas des anions fournit des informations sur l'évolution de l'énergie interne des ions stockés. Dans ce travail de thèse, le refroidissement de cations d'anthracène a été étudié dans un anneau de stockage électrostatique compact, le Mini-Ring, jusqu'à 8 ms. Les courbes de déclin spontané provenant de la dissociation par émission de fragment C2H2 ou H neutres montrent trois régions distinctives. Ces trois régions indiquent différents régimes de refroidissement en fonction du temps de stockage, la dissociation domine pour les temps inférieurs à 1 ms, l'effet de l'émission radiative entre alors en compétition avec la dissociation puis domine au-delà de 3 ms / The polycyclic aromatic hydrocarbon (PAH) molecules have been considered as possible carrier of the unidentified infrared emission bands from the interstellar medium (ISM) for about thirty years. The cooling dynamics of the PAH molecules which is essential to estimate their photostability and therefore their lifetime and size distributions in the ISM, has attracted numerous theoretical and experimental studies. In recent years, electrostatic storage devices (ESD) became powerful tool to investigate the cooling regime of molecules and clusters in a large time range from microseconds to seconds. Generally speaking, the decay of the emitted neutral yields due to dissociation of molecular cations or electron detachment of anions in such experiments carries information on the internal energy of the stored molecular ions. In this thesis work, the cooling regimes of anthracene cations are studied by following the time evolution of the internal energy distribution (IED) of the stored anthracene cations. A spontaneous neutral yield curve obtained from the stored molecular ions as a function of the storage time shows three distinguishable regions. The three regions indicate different cooling regimes at corresponding storage time range, i.e., the dissociation mechanism of the molecule dominates at storage time t < 1 ms, quenching of the dissociation by radiative cooling processes occurs during 1 < t < 3 ms and radiative cooling governs at t > 3 ms
73

Dynamique de refroidissement du cation naphtalène dans un anneau de stockage électrostatique / Cooling dynamics of naphthalene cations studied in an electrostatic storage ring

Ortega, Céline 25 June 2015 (has links)
L'étude des Hydrocarbures Aromatiques Polycycliques (PAH) a connu un intérêt croissant depuis une trentaine d'années, en raison notamment de leur possible présence dans le milieu interstellaire qui expliquerait l'observation des bandes d'émission IR encore non attribuées. Dans ce travail de thèse, la dynamique de refroidissement du cation naphtalène C10H8+, la plus petite molécule de la famille des PAH, est étudiée dans un anneau de stockage électrostatique, le Mini-Ring. La distribution en énergie interne des ions stockés est sondée en induisant la photo dissociation d'une fraction des ions par une excitation laser à la longueur d'onde 532 nm. La dynamique de refroidissement des cations photo-excités est observée en mesurant en fonction du temps le nombre de neutres émis par dissociation. La courbe de déclin du signal de neutres est directement reliée à la distribution en énergie interne des ions à l'instant de l'excitation laser. Cette distribution en énergie interne peut alors être déterminée à différents temps de stockage en analysant les courbes de déclin à l'aide d'un programme numérique développé pendant la thèse. L'évolution temporelle de la distribution met en évidence un processus de refroidissement rapide caractérisé par un taux de refroidissement compris entre 70 et 90 s−1 pour des énergies internes de 5.9 et 6.8 eV. Ce refroidissement rapide ne peut être expliqué par l'émission de photons infrarouges. Il est attribué à la "fluorescence de Poincaré" caractérisée par un processus de conversion interne inverse suivie de l'émission d'un photon dans le domaine du visible. Cette fluorescence de Poincaré ou fluorescence récurrente a été prédite il y a plus de 20 ans mais n'a jamais été mesurée directement à ce jour. Les taux de refroidissement mesurés lors de ce travail de thèse apportent une évidence indirecte de ce processus / The study of Polycyclic Aromatic Hydrocarbons (PAH) has been of increasing interest during the last thirty years: their possible presence in the interstellar medium is commonly invoked to explain the observation of still unassigned IR emission bands. In this thesis, the cooling dynamics of the naphthalene cations C10H8 +, the smallest molecule of the PAH family, is studied in an electrostatic storage ring, the Mini-Ring. Particularly, we consider the two main cooling processes for naphthalene cation, the dissociation and photon emission. Naphthalene molecules are ionized in an electron cyclotron resonance source (ECR), accelerated to 12 keV and then injected and stored in the Mini-Ring for several milliseconds. The internal energy distribution of the stored ions is probed by laser induced dissociation using an excitation wavelength at 532 nm. The cooling dynamics of the photo-excited cations is observed by measuring the number of emitted neutrals as a function of time. The decay curve of the neutral signal is directly related to the internal energy distribution of the ions at the excitation time. This internal energy distribution can then be determined at various storage times by analyzing the decay curves using a code developed during this thesis. The time evolution of the internal energy distribution shows a fast cooling process characterized by a cooling rate increasing from 70 to 90 s−1 for internal energies from 5.9 to 6.8 eV. This fast cooling process can’t be explained by infrared photons emission. It is attributed to the "Poincaré fluorescence " which involves an inverse internal conversion process followed by the emission of a visible photon. This fluorescence from thermally excited electron or recurrent fluorescence was predicted more than 20 years ago, but has never been measured directly up to now. The measured cooling rates in this thesis provide indirect evidence of this process
74

Study of solvated molecular ion stability in the gas-phase : cooling and irradiation / Étude de la stabilité d’ions moléculaires solvatés en phase gazeuse : refroidissement et irradiation

Bertier, Paul 23 October 2017 (has links)
Les radiations peuvent endommager notre environnement biologique mais elles peuvent aussi être bienfaisantes si elles sont contrôlées. L'action initiale des radiations à l'échelle microscopique consiste en une excitation électronique dans une molécule. L'observation de la redistribution de l'énergie dans l'environnement de cette molécule excitée est primordiale à la compréhension et à la description de l'effet des rayonnements dans les systèmes biomoléculaires. Les agrégats de molécules isolés en phase gazeuse constituent des systèmes modèles prometteurs pour étudier les interactions entre molécules sous irradiation. La première partie de ce travail décrit la construction et la validation d'une ligne de faisceau permettant la production de paquets d'agrégats moléculaires froid injectables dans l'anneau de stockage RICE à RIKEN. La ligne de faisceau est composée d'une source electrospray, d'un filtre en masse quadripolaire, de guides d'ions d'un tube d'accélération, la pièce centrale étant un piège à ions cryogénique refroidi à 4 K. Le paquet d'ions froids, dont les ions ont été sélectionnés en masse et accélérés jusqu'à 20 keV, a été sondé avec un laser. La ligne a été validée par la mesure d'un spectre d'action du bleu de méthylène. La seconde partie de ce travail s'appuie sur les expériences réalisées auprès du dispositif d'irradiation d'agrégats moléculaires (DIAM-IPNL). La méthode COINTOF-VMI permet la mesure de la distribution de vitesse des molécules d'eau évaporées à partir d'un agrégat après collision à haute vitesse avec un atome d'argon. Les distributions de vitesse mesurées pour des agrégats mixtes pyridine protonée et eau présentent deux composantes : une partie à basse vitesse qui correspond à une évaporation après redistribution de l'énergie dans l'agrégat, et une partie à haute vitesse où la molécule d'eau est évaporée avant redistribution de l'énergie. La comparaison des résultats avec les distributions calculées par dynamique moléculaire statistique montre que la partie basse vitesse peut être interprétée comme la contribution des deux possibilités d'excitation induites par la collision : l'excitation de la pyridine protonée ou l'excitation d'une des molécules d'eau / Radiation can damage our biological environment, but it can also be beneficial under certain controlled conditions. Initial action at microscopic scale consists of electronic excitation in molecules. The redistribution of this excitation energy to the environment is the primary process to be understood to describe the radiation effect on biomolecular system. Isolated molecular clusters in gas-phase are a promising model system to study the molecular interaction under radiation.The first part of this work describes the construction and the validation of a beamline which can produce bunches of cold molecular cluster ions to be injected in the RIKEN cryogenic electrostatic (RICE} storage ring. The beamline is composed of an electrospray ion source, a quadrupole mass filter, ion guides and an acceleration tube; with the main part being a cryogenic ion trap cool down to SK. The cold ion bunches, in which the ions have been mass selected and accelerated to 20keV, was probed with a laser. The beamline was successfully taken into operation and a measurement of the methylene blue action spectrum in gas-phase was carried out. The second part of this work rely on experiment realized with the dispositif d'irradiation d'agrégats moléculaires (DIAM-IPNL}. The COINTOF-VMI method allows the measurement of the velocity distributions of evaporated molecules from a cluster after high velocity collisions with an argon atom. The velocity distribution measured for mixed clusters protonated pyridine and water has two components: a low velocity part which corresponds to the evaporation of a water molecule after energy redistribution in the cluster, and a high velocity part in which the molecule is evaporated before total energy redistribution. Comparison with the distribution calculated by statistic molecular dynamic simulation shows that the low velocity part can be interpreted as the contribution of two possible excitations induced by collision: excitation on protonated pyridine and excitation on a water molecule
75

Optimisation énergétique des protocoles de communication des réseaux de capteurs sans fil / Energy optimization of communication protocols of the WSN

Randriatsiferana, Rivo Sitraka A. 03 December 2014 (has links)
Pour augmenter la durée de vie des réseaux de capteurs sans fil, une solution est d'améliorer l'efficacité énergétique des protocoles de communication. Le regroupement des nœuds du réseau de capteurs sans fil en cluster est l'une des meilleures méthodes. Cette thèse présente propose plusieurs améliorations en modifiant les paramètres du protocole de référence LEACH. Pour améliorer la distribution énergétique des "cluster-heads", nous proposons deux protocoles de clustering centralisés k-LEACH et sa version optimisée k-LEACH-VAR. Un algorithme distribué, appelé e-LEACH, est également proposé pour réduire l'échange d'information périodique entre les nœuds et la station de base lors de l'élection des "cluster-heads". Par ailleurs, le concept l'équilibrage énergétique est introduit dans les métriques d'élection pour éviter les surcharges des nœuds. Ensuite, nous présentons une version décentralisée de k-LEACH qui, en plus des objectifs précédents, intègre la consommation d'énergie globale du réseau. Ce protocole, appelé, k-LEACH-C2D, vise également à favoriser la scalabilité du réseau. Pour renforcer ce dernier et l'autonomie des réseaux, les deux protocoles de routage "multi-hop" probabiliste, dénotés FRSM et CB-RSM construisent des chemins élémentaires entre les "cluster-heads" et la station de base. Le protocole CB-RSM forme une hiérarchie des "cluster-heads" pendant la phase de formation des clusters, en mettant un accent sur l'auto-ordonnancement et l'auto-organisation entre les "cluster-heads" pour rendre les réseaux le plus "scalable". Ces différents protocoles reposent sur l'idée de base que les nœuds ayant l'énergie résiduelle la plus élevée et la plus faible variance de consommation de l'énergie deviennent "cluster-head". Nous constantans le rôle central de la consommation du nœud dans nos différentes propositions. Ce point fera l'objet de la dernière partie de cette thèse. Nous proposons une méthodologie pour caractériser expérimentalement la consommation d'un nœud. Les objectifs visent à mieux appréhender la consommation pour différentes séquences d'état du nœud. Enfin, nous proposons un modèle global de la consommation du nœud. / To increase the lifetime of wireless sensor networks, a solution is to improve the energy efficiency of the communication's protocol. The grouping of nodes in the wireless sensor network clustering is one of the best methods. This thesis proposes several improvements by changing the settings of the reference protocol LEACH. To improve the energy distribution of "cluster-heads", we propose two centralized clustering protocols LEACH and k-optimized version k-LEACH-VAR. A distributed algorithm, called e-LEACH, is proposed to reduce the periodic exchange of information between the nodes and the base station during the election of "cluster-heads". Moreover, the concept of energy balance is introduced in metric election to avoid overloading nodes. Then we presented a decentralized version of k-LEACH, which in addition to the previous objectives, integrates the overall energy consumption of the network. This protocol, called k-LEACH-C2D, also aims to promote the scalability of the network. To reinforce the autonomy and networks, both routing protocols "multi-hop" probability, denoted CB-RSM and FRSM build elementary paths between the "cluster-heads" and elected the base station. The protocol, CB-RSM, forms a hierarchy of "cluster-heads" during the training phase clusters, with an emphasis on self-scheduling and self-organization between "cluster-heads" to make the networks more scalable. These protocols are based on the basic idea that the nodes have the highest residual energy and lower variance of energy consumption become "cluster-head". We see the central role of consumption of the node in our proposals. This point will be the last part of this thesis. We propose a methodology to characterize experimentally the consumption of a node. The objectives are to better understand the consumption for different sequences of the node status. In the end, we propose a global model of the consumption of the node.
76

Machine Learning model applied to Reactor Dynamics / Maskininlärningsmodel Tillämpad på Reaktor Dynamik

Nikitopoulos, Dionysios Dimitrios January 2023 (has links)
This project’s idea revolved around utilizing the most recent techniques in MachineLearning, Neural Networks, and Data processing to construct a model to be used asa tool to determine stability during core design work. This goal will be achieved bycollecting distribution profiles describing the core state from different steady statesin five burn-up cycles in a reactor to serve as the dataset for training the model. Anadditional cycle will be reserved as a blind testing dataset for the trained model topredict. The variables that will be the target for the predictions are the decay ratioand the frequency since they describe the core stability.The distribution profiles extracted from the core simulator POLCA7 were subjectedto many different Data processing techniques to isolate the most relevant variablesto stability. The processed input variables were merged with the decay ratio andfrequency for those cases, as calculated with POLCA-T. Two different MachineLearning models, one for each output parameter, were designed with Pytorch toanalyze those labeled datasets. The goal of the project was to predict the outputvariables with an error lower than 0.1 for decay ratio and 0.05 for frequency. Themodels were able to predict the testing data with an RMSE of 0.0767 for decay ratioand 0.0354 for frequency.Finally, the trained models were saved and tasked with predicting the outputparameters for a completely unknown cycle. The RMSE was even better forthe unknown cycle, with 0.0615 for decay ratio and 0.0257 for frequency,respectively. / Idén bakom detta projekt var att använda de senaste teknikerna inom maskininlärning, neurala nätverk och databehandling för att konstruera en modell att använda som ett verktyg för att avgöra stabilitet under härddesignsarbete. Detta mål kommer uppnås genom att samla distribueringsprofiler av härdens tillstånd från olika stabila lägen i fem förbränningscyklar (burn-up cycles) i en reaktor, som tjänar som en datamängd att träna modellen på.En sjätte förbränningscykel användes som en datamängd för ett blindprov som den tränade modellen ska förutse. Variablerna som kommer tjäna som mål för förutsägelserna är sönderfallsförhållandet (decay ratio) och frekvensen, då dessa beskriver härdens stabilitet. Distribueringsprofilerna som extraherats från härdsimulatorn POLCA7 utsattes för många olika databehandlingstekniker för att isolera de mest relevanta variablerna för stabilitet. De behandlade indatavariablerna blandades med sönderfallsförhållandet och frekvensen för dessa fall, som beräknats med POLCA-T. Två olika maskininlärningsmodeller, en för varje utdataparameter, designades med Pytorch för att analysera dessa märkta datamängder. Projektets mål var att förutse utdatavariablerna med ett fel under 0.1 för sönderfallsförhållandet och 0.05 för frekvensen. Modellerna lyckades förutse testdatan med en RMSE på 0.0767 för sönderfallsförhållande och 0.0354 för frekvensen.Slutligen sparades de tränade modellerna och gavs uppgiften att förutse utdataparametrarna för en komplett okänd cykel. För den okända cykeln var RMSE ännu lägre, med 0.0615 för sönderfallsförhållande och 0.0257 för frekvensen.
77

Report on the first international workshop on energy data management (EnDM 2012)

Pedersen, Torben Bach, Lehner, Wolfgang, Hackenbroich, Gregor 13 December 2022 (has links)
The energy sector is one of the most active application domains being forced to re-think the current practice and apply data-management based IT solutions to provide a scalable and sustainable supply and distribution of energy. Challenges range from energy production by seamlessly incorporating renewable energy resources over energy distribution and monitoring to controlling energy consumption. Decisions are based on huge amounts of empirically collected data from smart meters, new energy sources (increasingly RES - renewable energy sources such as wind, solar, hydro, thermal, etc), new distributions mechanisms (Smart Grid), and new types of consumers and devices, e.g., electric cars.
78

Report on the second international workshop on energy data management (EnDM 2013)

Pedersen, Torben Bach, Lehner, Wolfgang 13 December 2022 (has links)
The energy sector is in transition–being forced to rethink the current practice and apply data-management based IT solutions to provide a scalable and sustainable supply and distribution of energy. Novel challenges range from renewable energy production over energy distribution and monitoring to controlling and moving energy consumption. Huge amounts of “Big Energy Data,” i.e., data from smart meters, new renewable energy sources (RES–such as wind, solar, hydro, thermal, etc), novel distributions mechanisms (Smart Grid), and novel types of consumers and devices, e.g., electric cars, are being collected and must be managed and analyzed to yield their potential.
79

Разработка информационной системы расчета оптимального распределения топливно-энергетических ресурсов в группе доменных печей : магистерская диссертация / Development of an information system for calculating the optimal distribution of energy resources in a group of blast furnaces

Бякова, М. А., Byakova, M. A. January 2018 (has links)
The thesis is devoted to the development of software for the system of optimal distribution of fuel and energy resources in the group of blast furnaces. In the course of work, the main stages of software development are considered: analysis of the subject area; creation of software architecture, user interface, database structure; development of algorithmic support and reference documentation; preparation of the distribution. The result of the work is a software product intended for the engineering and technological personnel of the blast furnace shop of the metallurgical plant. The results of the work can also be used in the educational process for training bachelors and undergraduates in the areas of "Metallurgy" and "Information Systems and Technologies". / Диссертационная работа посвящена разработке программного обеспечения системы оптимального распределения топливно-энергетических ресурсов в группе доменных печей. В ходе работы рассмотрены основные этапы разработки программного обеспечения: анализ предметной области; создание архитектуры программного обеспечения, пользовательского интерфейса, структуры базы данных; разработка алгоритмического обеспечения и справочной документации; подготовка дистрибутива. Результатом работы является программный продукт, предназначенный для инженерно-технологического персонала доменного цеха металлургического комбината. Результаты работы могут быть использованы также в учебном процессе для обучения бакалавров и магистрантов по направлениям «Металлургия» и «Информационные системы и технологии».
80

Complexities in Nonadiabatic Dynamics of Small Molecular Anions

Opoku-Agyeman, Bernice 24 May 2018 (has links)
No description available.

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