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Simulation schemes of an immiscible three-phase flow model for vapour explosion applications
No full textDans ce travail, on étudie la modélisation d'écoulement à trois phases non miscibles. L'application visée est l'explosion vapeur, qui risque de se produire lorsqu'un constituant liquide (S) (métal liquide à haute température) rentre en contact avec un constituant relativement froid, qui est en général de l'eau présente sous forme liquide (L) et vapeur (V). Les principaux transferts ayant lieu sont de type dynamique (vitesse-pression) et thermodynamique (échanges de chaleur et de masse). Plus précisément, les transferts de chaleur apparaissent entre les phases S, L et V, tandis que le transfert de masse ne peut survenir qu'entre les phases L et V du constituant eau. Les applications de type explosion vapeur (EV) génèrent des ondes de choc se propageant au sein du milieu et allant impacter des structures. Il est essentiel de noter que les temps de simulation réels, et les échelles de temps, sont courts. Il s'agit donc de simuler un modèle d'EDP avec lois de fermeture, qui permette de traiter des écoulements fortement instationnaires à trois phases immiscibles, avec génération d'ondes de choc et forts transferts thermiques et de masse, et qui soit conforme au second principe de la thermodynamique. Une fois le modèle d'EDP fermé donné, l'attention est portée sur la méthode numérique d'approximation de ce modèle. Une stratégie à pas fractionnaires est mise en place, afin de permettre de traiter un à un les différents effets de relaxation inclus dans le modèle. Différents cas tests numériques ont été réalisés, afin de s'assurer des propriétés des schémas considérés, et valider la cohérence des résultats numériques avec le comportement physique attendu de l'écoulement simuléThis PhD work consists of modeling a three-phase flow: liquid (L), gas (V) for the same component (water) and solid (S) for a second component (high temperature metal). Such a mix is characterized by the risk of occurrence of vapour explosion, where major transfers happen: in this bi-component environment dynamic transfers are important (speed / pressure) and thermodynamic exchanges (heat and mass transfers) also are at stake. More specifically, heat transfers occur between phases S, L and V, while the mass transfer can only occur between the phases L and V. The vapour explosion type applications (EV) generate shock waves propagating within the medium and can impact the structures. Finally, it is essential to note that the actual simulation time, and different time scales are short. The mission is, therefore, to compute an EDP model with closure laws, capable of dealing with strongly unsteady three-phase non-miscible flows, with generation of shock waves and high thermal and mass transfer, and consistent with the second principle of thermodynamics. The second step is to propose a Finite Volume numerical method adapted to the approximation of this model, and in the presence of shock waves. Numerical test cases are given in order to verify the properties of the considered schemes, attention is paid to the consistency between the numerical results and the expected physical behavior of the simulated flo
Schémas de simulation d'un modèle à trois phases immiscibles pour application à l'explosion vapeur
No full textThis PhD work consists of modeling a three-phase flow : liquid (L), gas (V) for the same component (water) and liquid (S) for a second component (high temperature liquid metal). Such a mix is characterized by the risk of occurrence of vapour explosion, where major transfers happen : in this bi-component environment dynamic transfers are important (speed / pressure) and thermodynamic exchanges (heat and mass transfers) also are at stake. More specifically, heat transfers occur between phases S, L and V, while the mass transfer can only occur between the phases L and V. The vapour explosion type applications (EV) generate shock waves propagating within the medium and can impact the structures. Finally, it is essential to note that the actual simulation time, and different time scales are short. The mission is, therefore, to compute an EDP model with closure laws, capable of dealing with strongly unsteady three-phase non-miscible flows, with generation of shock waves and high thermal and mass transfer, and consistent with the second principle of thermodynamics. The second step is to propose a Finite Volume numerical method adapted to the approximation of this model, and in the presence of shock waves. Numerical test cases are given in order to verify the properties of the considered schemes, attention is paid to the consistency between the numerical results and the expected physical behavior of the simulated flow.Dans ce travail de thèse, on étudie la problématique de modélisation d’écoulement à trois phases non miscibles. L’application visée est le phénomène d’explosion vapeur, qui risque de se produire lorsqu’un constituant liquide (S) (métal liquide à très haute température) rentre en contact avec un deuxième constituant (relativement froid) qui est en général de l’eau présente sous forme liquide (L) et vapeur (V). Les transferts principaux au sein de ce milieu bi-constituant sont de type dynamique (vitesse et pression) et thermodynamique (échanges de chaleur et de masse). Plus précisément, les transferts de chaleur apparaissent entre les phases S, L et V, tandis que le transfert de masse ne peut survenir qu’entre les phases L et V du constituant eau. Les applications de type explosion vapeur (EV) génèrent des ondes de choc se propageant au sein du milieu et allant impacter des structures. Il est enfin essentiel de noter que les temps de simulation réels, et les différentes échelles de temps, sont courts. Il s’agit donc de simuler un modèle d’EDP avec lois de fermeture, qui permette de traiter desécoulements fortement instationnaires à trois phases immiscibles, avec génération d’ondes de choc et forts transferts thermiques et de masse, et qui soit conforme au second principe de la thermodynamique. Une fois le modèle d’EDP fermé donné, l’attention est portée sur la méthode numérique d’approximation de ce modèle. La technique des Volumes Finis est adoptée, et une stratégie à pas fractionnaires est mise en place, afin de permettre de traiter un à un les différents effets de relaxation inclus dans le modèle. Des cas-tests numériques dedifférents degrés de complexité ont été réalisés, afin de s’assurer des propriétés des schémas considérés, et valider la cohérence entre les résultats numériques et le comportement physique attendu de l’écoulement simulé
Schémas de simulation d'un modèle à trois phases immiscibles pour application à l'explosion vapeur
No full textThis PhD work consists of modeling a three-phase flow : liquid (L), gas (V) for the same component (water) and liquid (S) for a second component (high temperature liquid metal). Such a mix is characterized by the risk of occurrence of vapour explosion, where major transfers happen : in this bi-component environment dynamic transfers are important (speed / pressure) and thermodynamic exchanges (heat and mass transfers) also are at stake. More specifically, heat transfers occur between phases S, L and V, while the mass transfer can only occur between the phases L and V. The vapour explosion type applications (EV) generate shock waves propagating within the medium and can impact the structures. Finally, it is essential to note that the actual simulation time, and different time scales are short. The mission is, therefore, to compute an EDP model with closure laws, capable of dealing with strongly unsteady three-phase non-miscible flows, with generation of shock waves and high thermal and mass transfer, and consistent with the second principle of thermodynamics. The second step is to propose a Finite Volume numerical method adapted to the approximation of this model, and in the presence of shock waves. Numerical test cases are given in order to verify the properties of the considered schemes, attention is paid to the consistency between the numerical results and the expected physical behavior of the simulated flow.Dans ce travail de thèse, on étudie la problématique de modélisation d’écoulement à trois phases non miscibles. L’application visée est le phénomène d’explosion vapeur, qui risque de se produire lorsqu’un constituant liquide (S) (métal liquide à très haute température) rentre en contact avec un deuxième constituant (relativement froid) qui est en général de l’eau présente sous forme liquide (L) et vapeur (V). Les transferts principaux au sein de ce milieu bi-constituant sont de type dynamique (vitesse et pression) et thermodynamique (échanges de chaleur et de masse). Plus précisément, les transferts de chaleur apparaissent entre les phases S, L et V, tandis que le transfert de masse ne peut survenir qu’entre les phases L et V du constituant eau. Les applications de type explosion vapeur (EV) génèrent des ondes de choc se propageant au sein du milieu et allant impacter des structures. Il est enfin essentiel de noter que les temps de simulation réels, et les différentes échelles de temps, sont courts. Il s’agit donc de simuler un modèle d’EDP avec lois de fermeture, qui permette de traiter desécoulements fortement instationnaires à trois phases immiscibles, avec génération d’ondes de choc et forts transferts thermiques et de masse, et qui soit conforme au second principe de la thermodynamique. Une fois le modèle d’EDP fermé donné, l’attention est portée sur la méthode numérique d’approximation de ce modèle. La technique des Volumes Finis est adoptée, et une stratégie à pas fractionnaires est mise en place, afin de permettre de traiter un à un les différents effets de relaxation inclus dans le modèle. Des cas-tests numériques dedifférents degrés de complexité ont été réalisés, afin de s’assurer des propriétés des schémas considérés, et valider la cohérence entre les résultats numériques et le comportement physique attendu de l’écoulement simulé
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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