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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
Effect of the microstructural variability on the behaviour of a UD glass/PA11 composite : from experimental characterization to multiscale modelling
No full textDans le domaine des transports, l’allègement des structures est une préoccupation de l’industrie moderne. À cet effet, les matériaux composites unidirectionnels à matrice polymère sont de plus en plus utilisés pour des applications structurelles. Pour mener à bien cette transition technologique, les campagnes expérimentales laborieuses et onéreuses sont progressivement réduites, laissant la place à une caractérisation “numérique“ supplétive et ciblée. C’est dans ce contexte que s’inscrit ce travail de thèse. Le matériau considéré est un composite à matrice thermoplastique (le Polyamide 11) et à renforts unidirectionnels de fibres de verre. Sous sollicitations mécaniques, la variabilité microstructurale, à l’échelle des constituants, engendre des contraintes multi-axiales importantes qu’il est nécessaire d’évaluer. C’est notamment le cas dans les zones où la matrice est confinée par le renfort. Étudier l’échelle microscopique se révèle primordial pour comprendre et simuler les mécanismes de déformation spécifiques à la matrice thermoplastique.En première partie, une campagne expérimentale est réalisée sur le polymère thermoplastique massif. Des éprouvettes axisymétriques entaillées sont sollicitées en traction monotone et suivies in situ en tomographie aux rayons X. Un phénomène de cavitation est observé. Les grandeurs macroscopiques (ouverture d’entaille, réduction diamétrale. . .) mais aussi microscopiques (évolution des cavités considérées en cluster et individuellement)sont analysées de manières qualitative et quantitative.Un modèle Éléments Finis poro-viscoplastique est ensuite proposé et calibré afin de prendre en compte les mécanismes spécifiques de déformation et d’endommagement du polymère observés expérimentalement. La seconde partie est consacrée à l’étude numérique du matériau composite unidirectionnel. La représentation de la microstructure réelle est permise par la génération de cellules périodiques aléatoires et représentatives(vis-à-vis de descripteurs morphologiques). Des calculs micromécaniques sont alors menés et permettent d’accéder aux mécanismes de déformation, aux grandeurs locales et au comportement mécanique du composite (en élasticité linéaire et au-delà). Une attention particulière est portée à la représentativité des grandeurs calculées. Enfin, une démarche multi-échelle est proposée. Une homogénéisation numérique par un milieu de substitution permet de réaliser des calculs de structure tandis qu’une relocalisation sur certains points critiques donne accès aux grandeurs locales.In the field of transport, research for reducing the weight of structures is a continuing preoccupation for the industry. For this reason, polymer matrix composite materials are being used increasingly for structural applications. To succeed with this technological transition numerical modelling plays a significant role as cumbersome and costly experimental campaigns are being limited. This is the background to this thesis work.The material considered is composed of a thermoplastic resin (Polyamide 11) with a unidirectional glass fibre reinforcement. Under mechanical loadings, the microsctructural variability, at the constituent length scale, leads to important multi-axial stresses that need to be evaluated. This is notably true in zones where the matrix is particularly confined. Studying the microscopic scale is of paramount importance in order to understand and simulate specific strain mechanisms of the thermoplastic resin.In the first part, an experimental campaign has been conducted on the plain thermoplastic polymer. Axisymetric notched specimens were tested under uniaxial monotonous tension and monitored with in-situ X-ray synchrotron computed tomography. A cavitation phenomenon has been observed. Not only macroscopic quantities (notch opening displacement, reduction in diameter…) but also microscopic (evolution of voids considered as a cluster or individually) have been analyzed both quantitatively and qualitatively. A finite element model is subsequently proposed and calibrated to take into account the specific strain deformations and damage experimentally observed with this polymer.The second part is dedicated to a numerical study of the unidirectional composite material. A representation of the real microstructure has been tackled with the generation of virtual random and periodic cells in a way that nevertheless is truely morphologically representative. Micromechanics computations have been carried out and give access to strain mechanisms, to local quantities and to the composite material behaviour (in linear elasticity and beyond). Special attention is paid to the representativeness of the computed quantities. Finally, a multiscale approach is proposed. Structural computations have been possible due to a numerical homogenization based on an homogeneous equivalent medium whilst a relocalisation gives access to local quantities in critical zones of the structure
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
Effet de la variabilité microstructurale sur le comportement d’un composite UD verre/PA11 : de la caractérisation expérimentale à la modélisation multi-échelle
No full textIn the field of transport, research for reducing the weight of structures is a continuing preoccupation for the industry. For this reason, polymer matrix composite materials are being used increasingly for structural applications. To succeed with this technological transition numerical modelling plays a significant role as cumbersome and costly experimental campaigns are being limited. This is the background to this thesis work.The material considered is composed of a thermoplastic resin (Polyamide 11) with a unidirectional glass fibre reinforcement. Under mechanical loadings, the microsctructural variability, at the constituent length scale, leads to important multi-axial stresses that need to be evaluated. This is notably true in zones where the matrix is particularly confined. Studying the microscopic scale is of paramount importance in order to understand and simulate specific strain mechanisms of the thermoplastic resin.In the first part, an experimental campaign has been conducted on the plain thermoplastic polymer. Axisymetric notched specimens were tested under uniaxial monotonous tension and monitored with in-situ X-ray synchrotron computed tomography. A cavitation phenomenon has been observed. Not only macroscopic quantities (notch opening displacement, reduction in diameter…) but also microscopic (evolution of voids considered as a cluster or individually) have been analyzed both quantitatively and qualitatively. A finite element model is subsequently proposed and calibrated to take into account the specific strain deformations and damage experimentally observed with this polymer.The second part is dedicated to a numerical study of the unidirectional composite material. A representation of the real microstructure has been tackled with the generation of virtual random and periodic cells in a way that nevertheless is truely morphologically representative. Micromechanics computations have been carried out and give access to strain mechanisms, to local quantities and to the composite material behaviour (in linear elasticity and beyond). Special attention is paid to the representativeness of the computed quantities. Finally, a multiscale approach is proposed. Structural computations have been possible due to a numerical homogenization based on an homogeneous equivalent medium whilst a relocalisation gives access to local quantities in critical zones of the structure.Dans le domaine des transports, l’allègement des structures est une préoccupation de l’industrie moderne. À cet effet, les matériaux composites unidirectionnels à matrice polymère sont de plus en plus utilisés pour des applications structurelles. Pour mener à bien cette transition technologique, les campagnes expérimentales laborieuses et onéreuses sont progressivement réduites, laissant la place à une caractérisation “numérique“ supplétive et ciblée. C’est dans ce contexte que s’inscrit ce travail de thèse. Le matériau considéré est un composite à matrice thermoplastique (le Polyamide 11) et à renforts unidirectionnels de fibres de verre. Sous sollicitations mécaniques, la variabilité microstructurale, à l’échelle des constituants, engendre des contraintes multi-axiales importantes qu’il est nécessaire d’évaluer. C’est notamment le cas dans les zones où la matrice est confinée par le renfort. Étudier l’échelle microscopique se révèle primordial pour comprendre et simuler les mécanismes de déformation spécifiques à la matrice thermoplastique.En première partie, une campagne expérimentale est réalisée sur le polymère thermoplastique massif. Des éprouvettes axisymétriques entaillées sont sollicitées en traction monotone et suivies in situ en tomographie aux rayons X. Un phénomène de cavitation est observé. Les grandeurs macroscopiques (ouverture d’entaille, réduction diamétrale. . .) mais aussi microscopiques (évolution des cavités considérées en cluster et individuellement)sont analysées de manières qualitative et quantitative.Un modèle Éléments Finis poro-viscoplastique est ensuite proposé et calibré afin de prendre en compte les mécanismes spécifiques de déformation et d’endommagement du polymère observés expérimentalement. La seconde partie est consacrée à l’étude numérique du matériau composite unidirectionnel. La représentation de la microstructure réelle est permise par la génération de cellules périodiques aléatoires et représentatives(vis-à-vis de descripteurs morphologiques). Des calculs micromécaniques sont alors menés et permettent d’accéder aux mécanismes de déformation, aux grandeurs locales et au comportement mécanique du composite (en élasticité linéaire et au-delà). Une attention particulière est portée à la représentativité des grandeurs calculées. Enfin, une démarche multi-échelle est proposée. Une homogénéisation numérique par un milieu de substitution permet de réaliser des calculs de structure tandis qu’une relocalisation sur certains points critiques donne accès aux grandeurs locales
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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