1,720,958 research outputs found
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
Etude de la réponse forcée des OGV d'un moteur UHBR sous ingestion de vortex de sol
No full textDuring the take-off phase of an aircraft in crosswind conditions, the flow ingested by the engine can interact with the ground and the inlet, resulting in the formation of a ground vortex in front of the engine. This phenomenon is particularly common in new turbomachinery designs with high bypass ratios and short intake. The ground vortex is ingested by the engine and interacts with the rotating fan, causing the vortex to chop. This complex, unsteady flow is convected to the Outlet Guide Vane (OGV) and is seen as a source of aerodynamic excitation by the blades. Under certain test conditions, this leads to high levels of forced response affecting the structure of the OGV. These vibrations can lead to blade fatigue or failure. The aim of this thesis is to characterize the source of aerodynamic excitation of OGVs generated by the interaction between the fan and the ground vortex, using numerical turbulence models of different fidelity levels (URANS, ZDES), in a progressive approach including the implementation of a representative academic test case. The high-fidelity ZDES calculation is used to set a reference database of the interaction between fan blades and an incident vortex. Secondly, using the results of the first phase, a numerical strategy is developed to predict the amplitude of vibration of the OGVs subjected to the transformed vortex in the case of an industrial configuration by a decoupled aeroelastic simulation, while analyzing the source of aerodynamic excitation and the aeroelastic phenomena involved.Lors de la phase de décollage d’un aéronef par vent de travers, l’écoulement ingéré par le moteur peut interagir avec le sol et la nacelle, entrainant la formation d’un vortex de sol devant l’entrée d’air. Ce phénomène est particulièrement rencontré par les nouvelles architectures de turbomachines à haut taux de dilution et entrée courte. Le vortex de sol est ingéré par le moteur et interagit avec le fan en rotation, entrainant le hachage du tourbillon. Cet écoulement extrêmement complexe et instationnaire est convecté jusqu’à la roue redresseuse de sortie du flux secondaire (OGV) et est vu comme une source d’excitation aérodynamique par les aubages. Cela conduit dans certaines conditions observées en essai à de forts niveaux de réponse forcée affectant la structure de l'OGV. Ces vibrations peuvent entrainer des phénomènes de fatigue ou la rupture de l'aube.L’objectif de la thèse est de caractériser la source d’excitation aérodynamique des OGV générée par l’interaction entre le fan et le vortex de sol à l'aide de modèles numériques de turbulence de différents niveaux de fidélité (URANS, ZDES), dans une approche progressive incluant la mise en œuvre d’un cas-test académique représentatif. Le calcul haute-fidélité ZDES permet l’établissement d’une base de données de référence de l’interaction entre des aubes fan et un vortex incident. Dans un second temps, par exploitation des acquis de la première phase, une stratégie numérique est développée afin de prévoir l’amplitude de vibration des OGV soumis au vortex transformé dans le cas d'une configuration industrielle par un calcul aéroélastique découplé, tout en analysant la source d’excitation aérodynamique et les phénomènes aéroélastiques mis en jeu
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
Study of the forced response of the OGV of a UHBR engine under ground vortex ingestion
No full textLors de la phase de décollage d’un aéronef par vent de travers, l’écoulement ingéré par le moteur peut interagir avec le sol et la nacelle, entrainant la formation d’un vortex de sol devant l’entrée d’air. Ce phénomène est particulièrement rencontré par les nouvelles architectures de turbomachines à haut taux de dilution et entrée courte. Le vortex de sol est ingéré par le moteur et interagit avec le fan en rotation, entrainant le hachage du tourbillon. Cet écoulement extrêmement complexe et instationnaire est convecté jusqu’à la roue redresseuse de sortie du flux secondaire (OGV) et est vu comme une source d’excitation aérodynamique par les aubages. Cela conduit dans certaines conditions observées en essai à de forts niveaux de réponse forcée affectant la structure de l'OGV. Ces vibrations peuvent entrainer des phénomènes de fatigue ou la rupture de l'aube.L’objectif de la thèse est de caractériser la source d’excitation aérodynamique des OGV générée par l’interaction entre le fan et le vortex de sol à l'aide de modèles numériques de turbulence de différents niveaux de fidélité (URANS, ZDES), dans une approche progressive incluant la mise en œuvre d’un cas-test académique représentatif. Le calcul haute-fidélité ZDES permet l’établissement d’une base de données de référence de l’interaction entre des aubes fan et un vortex incident. Dans un second temps, par exploitation des acquis de la première phase, une stratégie numérique est développée afin de prévoir l’amplitude de vibration des OGV soumis au vortex transformé dans le cas d'une configuration industrielle par un calcul aéroélastique découplé, tout en analysant la source d’excitation aérodynamique et les phénomènes aéroélastiques mis en jeu.During the take-off phase of an aircraft in crosswind conditions, the flow ingested by the engine can interact with the ground and the inlet, resulting in the formation of a ground vortex in front of the engine. This phenomenon is particularly common in new turbomachinery designs with high bypass ratios and short intake. The ground vortex is ingested by the engine and interacts with the rotating fan, causing the vortex to chop. This complex, unsteady flow is convected to the Outlet Guide Vane (OGV) and is seen as a source of aerodynamic excitation by the blades. Under certain test conditions, this leads to high levels of forced response affecting the structure of the OGV. These vibrations can lead to blade fatigue or failure. The aim of this thesis is to characterize the source of aerodynamic excitation of OGVs generated by the interaction between the fan and the ground vortex, using numerical turbulence models of different fidelity levels (URANS, ZDES), in a progressive approach including the implementation of a representative academic test case. The high-fidelity ZDES calculation is used to set a reference database of the interaction between fan blades and an incident vortex. Secondly, using the results of the first phase, a numerical strategy is developed to predict the amplitude of vibration of the OGVs subjected to the transformed vortex in the case of an industrial configuration by a decoupled aeroelastic simulation, while analyzing the source of aerodynamic excitation and the aeroelastic phenomena involved
Etude de la réponse forcée des OGV d'un moteur UHBR sous ingestion de vortex de sol
No full textDuring the take-off phase of an aircraft in crosswind conditions, the flow ingested by the engine can interact with the ground and the inlet, resulting in the formation of a ground vortex in front of the engine. This phenomenon is particularly common in new turbomachinery designs with high bypass ratios and short intake. The ground vortex is ingested by the engine and interacts with the rotating fan, causing the vortex to chop. This complex, unsteady flow is convected to the Outlet Guide Vane (OGV) and is seen as a source of aerodynamic excitation by the blades. Under certain test conditions, this leads to high levels of forced response affecting the structure of the OGV. These vibrations can lead to blade fatigue or failure. The aim of this thesis is to characterize the source of aerodynamic excitation of OGVs generated by the interaction between the fan and the ground vortex, using numerical turbulence models of different fidelity levels (URANS, ZDES), in a progressive approach including the implementation of a representative academic test case. The high-fidelity ZDES calculation is used to set a reference database of the interaction between fan blades and an incident vortex. Secondly, using the results of the first phase, a numerical strategy is developed to predict the amplitude of vibration of the OGVs subjected to the transformed vortex in the case of an industrial configuration by a decoupled aeroelastic simulation, while analyzing the source of aerodynamic excitation and the aeroelastic phenomena involved.Lors de la phase de décollage d’un aéronef par vent de travers, l’écoulement ingéré par le moteur peut interagir avec le sol et la nacelle, entrainant la formation d’un vortex de sol devant l’entrée d’air. Ce phénomène est particulièrement rencontré par les nouvelles architectures de turbomachines à haut taux de dilution et entrée courte. Le vortex de sol est ingéré par le moteur et interagit avec le fan en rotation, entrainant le hachage du tourbillon. Cet écoulement extrêmement complexe et instationnaire est convecté jusqu’à la roue redresseuse de sortie du flux secondaire (OGV) et est vu comme une source d’excitation aérodynamique par les aubages. Cela conduit dans certaines conditions observées en essai à de forts niveaux de réponse forcée affectant la structure de l'OGV. Ces vibrations peuvent entrainer des phénomènes de fatigue ou la rupture de l'aube.L’objectif de la thèse est de caractériser la source d’excitation aérodynamique des OGV générée par l’interaction entre le fan et le vortex de sol à l'aide de modèles numériques de turbulence de différents niveaux de fidélité (URANS, ZDES), dans une approche progressive incluant la mise en œuvre d’un cas-test académique représentatif. Le calcul haute-fidélité ZDES permet l’établissement d’une base de données de référence de l’interaction entre des aubes fan et un vortex incident. Dans un second temps, par exploitation des acquis de la première phase, une stratégie numérique est développée afin de prévoir l’amplitude de vibration des OGV soumis au vortex transformé dans le cas d'une configuration industrielle par un calcul aéroélastique découplé, tout en analysant la source d’excitation aérodynamique et les phénomènes aéroélastiques mis en jeu
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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