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Étude et caractérisation de l’usure et l’échauffement des matériaux structuraux aéronautiques en cas d’atterrissage d’urgence « trains rentrés »
No full textDuring wheels-up emergency landings, wear and heat phenomena underneath the dry friction between the aircraft and the runway might endanger the passengers. Thus it is mandatory to design experiments to study and characterise these phenomena. At this stage of research, the most accessible solution consists of laboratory experiments, that is to say at a lower scale. The aim of the research work is to design tribological laboratory experiments that are representative of wheels-up situations. In parallel with this design, the PhD work is based on an existing tribometer to identify and propose methods for characterising the physics underlying wear and heat for tribological triplets close to the crash situations' ones. Based on concrete pad-on-aluminium alloy disc experiments, at first, a multi-scale analysis method was proposed to determine the wear scenario within the framework of the three-body tribology. This was followed by the study of the heat in the triplet focusing on the heat transmitted by the disc to its support. Finally, a reflection was carried on downscaling, through a dimensional analysis of the wear and heat scenarios. The PhD work highlighted the protective role of the third solid body enhanced by the structure in certain tribological triplets close to the crash situations' ones. It also allows the comparison of the performances of triplets containing a CFRP with those containing an aluminium alloy.Durant les atterrissages d'urgence "trains rentrés", les phénomènes d'usure et d'échauffement qui pilotent le frottement sec aéronef/piste constituent un danger pour les passagers. Il est donc primordial de concevoir des expériences pour étudier et caractériser ces phénomènes. À ce stade des recherches, la solution la plus accessible consiste en des expériences en laboratoire et donc à échelle réduite. Les travaux de recherche ont pour objectif la conception d'expériences tribologiques en laboratoire représentatives des atterrissages "trains rentrés". En parallèle de cette conception, les travaux de thèse s'appuient sur un tribomètre existant pour identifier et proposer des méthodes de caractérisation de la physique sous-jacente à l'usure et l'échauffement pour des triplets tribologiques proches du cas réel. En se basant sur des expériences de type "patin en béton sur disque rotatif en alliage d'aluminium", il s'est d'abord agi de proposer une méthode d'analyse multi-échelle pour déterminer le processus tribologique dans le cadre de la tribologie à trois corps. S'en est suivi l'étude de l'échauffement du système tribologique avec une attention particulière portée sur la chaleur transmise par le disque à son support. Enfin, une réflexion a été faite sur le changement d'échelle, à travers une analyse dimensionnelle des scénarios d'usure et d'échauffement proposés. Les travaux de recherche ont permis de mettre en évidence le rôle protecteur (portance) du troisième corps solide favorisé par la configuration structurale dans certains triplets tribologiques proches du cas réel. Ils permettent également une comparaison des performances de triplets contenant un PRFC à ceux contenant un alliage d'aluminium
Study and characterization of wear and heat phenomena for aircraft’s structural materials during wheels-up emergency landing
No full textDurant les atterrissages d'urgence "trains rentrés", les phénomènes d'usure et d'échauffement qui pilotent le frottement sec aéronef/piste constituent un danger pour les passagers. Il est donc primordial de concevoir des expériences pour étudier et caractériser ces phénomènes. À ce stade des recherches, la solution la plus accessible consiste en des expériences en laboratoire et donc à échelle réduite. Les travaux de recherche ont pour objectif la conception d'expériences tribologiques en laboratoire représentatives des atterrissages "trains rentrés". En parallèle de cette conception, les travaux de thèse s'appuient sur un tribomètre existant pour identifier et proposer des méthodes de caractérisation de la physique sous-jacente à l'usure et l'échauffement pour des triplets tribologiques proches du cas réel. En se basant sur des expériences de type "patin en béton sur disque rotatif en alliage d'aluminium", il s'est d'abord agi de proposer une méthode d'analyse multi-échelle pour déterminer le processus tribologique dans le cadre de la tribologie à trois corps. S'en est suivi l'étude de l'échauffement du système tribologique avec une attention particulière portée sur la chaleur transmise par le disque à son support. Enfin, une réflexion a été faite sur le changement d'échelle, à travers une analyse dimensionnelle des scénarios d'usure et d'échauffement proposés. Les travaux de recherche ont permis de mettre en évidence le rôle protecteur (portance) du troisième corps solide favorisé par la configuration structurale dans certains triplets tribologiques proches du cas réel. Ils permettent également une comparaison des performances de triplets contenant un PRFC à ceux contenant un alliage d'aluminium.During wheels-up emergency landings, wear and heat phenomena underneath the dry friction between the aircraft and the runway might endanger the passengers. Thus it is mandatory to design experiments to study and characterise these phenomena. At this stage of research, the most accessible solution consists of laboratory experiments, that is to say at a lower scale. The aim of the research work is to design tribological laboratory experiments that are representative of wheels-up situations. In parallel with this design, the PhD work is based on an existing tribometer to identify and propose methods for characterising the physics underlying wear and heat for tribological triplets close to the crash situations' ones. Based on concrete pad-on-aluminium alloy disc experiments, at first, a multi-scale analysis method was proposed to determine the wear scenario within the framework of the three-body tribology. This was followed by the study of the heat in the triplet focusing on the heat transmitted by the disc to its support. Finally, a reflection was carried on downscaling, through a dimensional analysis of the wear and heat scenarios. The PhD work highlighted the protective role of the third solid body enhanced by the structure in certain tribological triplets close to the crash situations' ones. It also allows the comparison of the performances of triplets containing a CFRP with those containing an aluminium alloy
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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