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Contribution au développement des nouvelles méthodes de mise à la terre (MALT) basées sur l’utilisation des bétons et/ou géopolymères électriquement conducteurs
Get PDFCe mémoire explore le développement de nouvelles méthodes de mise à la terre, en particulier l'intégration du béton électriquement conducteur (BEC) avec la technologie des électrodes enrobées de béton (EEB), appelée EE-BEC, en tant qu'approche innovante des systèmes de mise à la terre des sous-stations (SGS) dans le but de protéger les équipements électriques, le personnel, le public et les animaux contre les défauts pouvant apparaître dans les réseaux électriques. L'étude commence par la validation du logiciel commercial Comsol Multiphysics® de méthode des éléments finis (FEM) par l'analyse d'un SGS de cuivre conventionnel. Par la suite, des simulations numériques sont effectuées sur le système de mise à la terre EE-BEC, en faisant correspondre les dimensions de la grille de cuivre pour validation. Divers paramètres du système EE-BEC sont étudiés, notamment la géométrie BEC, les dimensions, la résistivité et le diamètre des barres d'armature. Les résultats révèlent que les systèmes EE-BEC surpassent les SGS traditionnels, en particulier dans les scénarios à haute résistivité du sol. Les paramètres clés influençant la résistance de mise à la terre, les tensions de contact et de pas sont identifiés comme la surface de section et la résistivité de BEC. Le système EE-BEC proposé présente des avantages en termes d'efficacité, de durabilité, de facilité de conception et de mise en oeuvre par rapport aux SGS conventionnels. De plus, ce travail présente une étude numérique d'une nouvelle méthode de mise à la terre adaptée aux sols gelés saisonniers, une condition répandue dans les climats froids comme le Canada. L'étude comprend un modèle de sol à deux couches pour simuler un sol gelé saisonnier, explorant l'impact de l'épaisseur de la couche supérieure sur divers paramètres du système EE-BEC, tels que la profondeur d'enfouissement et la longueur supplémentaire des piliers. Les résultats indiquent des performances supérieures du système EE-BEC par rapport aux grilles de cuivre conventionnelles, en particulier lorsque l'épaisseur de la couche gelée dépasse la profondeur d'enfouissement de la grille de mise à la terre. Cette condition a tendance à augmenter la résistance de grille et les tensions de pas et de contact, soulignant l'efficacité du système de mise à la terre EE-BEC proposé dans des environnements difficiles. En conclusion, la mise en oeuvre d'une grille à petite échelle a constitué une simulation précieuse pour reproduire les comportements réels de notre système innovant MALT dans des climats froids. Les résultats de cette étude soulignent l'efficacité remarquable du système EE-BEC en tant qu'alternative supérieure au système conventionnel en cuivre, même dans les régions caractérisées par une résistivité élevée. Cette découverte renforce non seulement la viabilité du système proposé, mais le positionne également comme une solution robuste capable de relever les défis posés par des conditions environnementales extrêmes. Le succès du système EE-BEC dans l'atténuation des problèmes liés à la résistivité souligne encore son potentiel à révolutionner les systèmes de mise à la terre, offrant une alternative fiable et efficace pour les applications de sous-stations, en particulier dans les zones froides et à haute résistivité.
This dissertation explores the development of new grounding methods, particularly the integration of electrically conductive concrete (ECON) with Concrete-Encased Electrode (CEE) technology, termed ECON-EE. This serves as an innovative approach to substation grounding systems (SGS) aimed at safeguarding electrical equipment, personnel, the public, and animals against faults that may occur in electrical networks. The study begins with the validation of the commercial finite element method (FEM) software, Comsol Multiphysics®, through the analysis of a conventional copper SGS. Subsequently, numerical simulations are conducted on the ECON-EE grounding system, matching the dimensions of the copper grid for validation. Various parameters of the ECON-EE system are studied, including ECON geometry, dimensions, resistivity, and the diameter of reinforcing bars. The results reveal that ECON-EE systems outperform traditional SGS, particularly in scenarios with high soil resistivity. Key parameters influencing grounding resistance, touch, and step voltages are identified as the section area and resistivity of the ECON. The proposed ECON-EE system presents advantages in terms of efficiency, durability, and simplicity of design and implementation compared to conventional SGS. Additionally, this work presents a numerical investigation of a new grounding method applicable to seasonal frozen soil, a condition prevalent in cold climates like Canada. The study includes a two-layer ground model to simulate seasonal frozen soil, exploring the impact of the upper-layer thickness on various ECON-EE system parameters, such as burial depth and length of additional pillars. The results indicate superior performance of the ECON-EE system over conventional copper grids, especially when the thickness of the frozen layer exceeds the burial depth of the grounding grid. This condition tends to increase grid resistance and step and touch voltages, underscoring the efficiency of the proposed ECON-EE grounding system in challenging environments. In conclusion, the implementation of a small-scale grid served as a valuable simulation to replicate the real-world behaviors of our innovative MALT system in cold climates. The results of this study underscore the remarkable effectiveness of the ECON-EE system as a superior alternative to the conventional copper system, even in regions characterized by high resistivity. This finding not only reinforces the viability of our proposed system but also positions it as a robust solution capable of addressing the challenges posed by extreme environmental conditions. The success of the ECON-EE system in mitigating issues related to resistivity further emphasizes its potential to revolutionize grounding systems, offering a reliable and efficient alternative for substation applications, particularly in cold and high-resistivity areas
Mortar spectral element discretization of Darcy's equations in nonhomogeneous medium
Get PDFWe consider Darcy's equations with piecewise continuous coeffcients in a bounded two-dimensional domain. We propose a spectral element discretization of this problem wich relies on the mortar domain decomposition technique. We prove optimal error estimates. We also performe numerical analysis of the discrete problem and present numerical experiments. They turn out to be in good coherency with the theoretical results
Discrétisation spectrale et par éléments spectraux des équations de Darcy
No full textPARIS-BIUSJ-Physique recherche (751052113) / SudocPARIS-BIUSJ-Mathématiques rech (751052111) / SudocSudocFranceF
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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