1,721,001 research outputs found
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
Effet de l'excitation des structures cylindriques par les tourbillons alternés : modélisation de l'amplitude pour les codes de construction
No full textVibrations due to the alternating shedding of vortexes (vortex-induced vibrations) are a great concern when designing industrial chimneys. These vibrations are complex and can give large amplitudes of motion at low speeds. There are many methods for predicting these vibrations (e.g. wind tunnels or predictive models) but they need improvements.An experiment in a large wind tunnel revealed important, new knowledge on the vortex-shedding frequency which will help predict vortex-induced vibrations using wind tunnels. Instead of a finding a single vortex-shedding frequency, either in the range 0.25-0.27 or near 0.2 as in previous studies, two distinct Strouhal numbers were found at around 0.2 and 0.25.In addition, the spatial unsteady pressure distributions and forcing results at large-scale helped validate an experimental method for simulating the high Reynolds number flow in smaller wind tunnels. These tests showed that surface roughness can trigger high Reynolds number flow and mostly reproduce the spatial pressure distributions. While promising, the vortex-shedding frequencies and forces were different at small-scale than at large-scale.Turbulent atmospheric boundary layers were found to affect the response more than the surface roughness in 3D aeroelastic tests. When testing a rough and a smooth cylinder with a turbulent boundary layer, the responses were similar but the vibration amplitudes and differences increased when testing without the boundary layer. The importance of the turbulent boundary layer on the response was corroborated in a field experiment on a chimney exposed to naturally varying turbulence profiles.Lastly, ways to improve analytic modeling of predicting vortex-induced vibrations were found by finding the best model for a given situation. This was done using two classical design models and a newly approximated model and the best predictive model was found to depend on the product of mass and damping. When this product was low, the newly approximated model worked best while one of the design models was better when the mass-damping product was high.Les vibrations causées par le détachement de tourbillons alternés (vibrations induites par vortex) constituent une préoccupation majeure lors de la conception de cheminées industrielles. Cette excitation est due à un couplage non linéaire entre le lâcher tourbillonnaire et le mouvement d’oscillation. Elle peut engendrer des amplitudes de vibration élevées à faible vitesse de vent. Il existe de nombreuses méthodes pour les prédire et la plupart d'entre elles doivent être améliorées.Pour améliorer les prédictions en soufflerie, il est nécessaire de connaître l'écoulement autour des cylindres circulaires à des nombres de Reynolds élevés. Une expérience dans une grande soufflerie a révélé une nouvelle information concernant la fréquence de lâcher des tourbillons à grands nombres de Reynolds : au lieu d'une seule fréquence, nous avons trouvé deux nombres de Strouhal bien distincts, 0.2 et 0.25 environ. Or de nombreuses études antérieures avaient trouvé des nombres de Strouhal dispersés dans l'intervalle 0.2-0.25 sans plus de précision.De plus, les distributions de pression instationnaire et les mesures de force à grande échelle sont utilisées pour valider une méthode expérimentale pour simuler un écoulement à haut nombre de Reynolds dans une soufflerie à petite échelle. Des éléments de rugosité collés sur la surface peuvent déclencher un écoulement à nombre de Reynolds élevé et reproduire en grande partie les distributions de pression instationnaire. Néanmoins, les fréquences de lâcher de tourbillons et les efforts restent différents à petite échelle.Dans des essais aéroélastiques 3D, on trouve que la couche limite atmosphérique turbulente affecte davantage l'écoulement que les rugosités artificielles. Sans couche limite atmosphérique, la réponse augmente et diffère entre le cylindre rugueux et le cylindre lisse. Ces résultats ont été corroborés par une expérience vraie grandeur sur site avec des profils de couche limite variant naturellement.Une autre méthode pour prédire les vibrations induites par les tourbillons consiste à utiliser des modèles analytiques. Pour trouver le meilleur modèle, deux modèles classiques sont comparés à un nouveau modèle approximatif. Les résultats dépendent du produit masse-amortissement. Lorsque ce produit est faible, le nouveau modèle fonctionne mieux, tandis que l'un des modèles classiques reste meilleur lorsque ce produit masse-amortissement est élevé
Effet de l'excitation des structures cylindriques par les tourbillons alternés : modélisation de l'amplitude pour les codes de construction
No full textVibrations due to the alternating shedding of vortexes (vortex-induced vibrations) are a great concern when designing industrial chimneys. These vibrations are complex and can give large amplitudes of motion at low speeds. There are many methods for predicting these vibrations (e.g. wind tunnels or predictive models) but they need improvements.An experiment in a large wind tunnel revealed important, new knowledge on the vortex-shedding frequency which will help predict vortex-induced vibrations using wind tunnels. Instead of a finding a single vortex-shedding frequency, either in the range 0.25-0.27 or near 0.2 as in previous studies, two distinct Strouhal numbers were found at around 0.2 and 0.25.In addition, the spatial unsteady pressure distributions and forcing results at large-scale helped validate an experimental method for simulating the high Reynolds number flow in smaller wind tunnels. These tests showed that surface roughness can trigger high Reynolds number flow and mostly reproduce the spatial pressure distributions. While promising, the vortex-shedding frequencies and forces were different at small-scale than at large-scale.Turbulent atmospheric boundary layers were found to affect the response more than the surface roughness in 3D aeroelastic tests. When testing a rough and a smooth cylinder with a turbulent boundary layer, the responses were similar but the vibration amplitudes and differences increased when testing without the boundary layer. The importance of the turbulent boundary layer on the response was corroborated in a field experiment on a chimney exposed to naturally varying turbulence profiles.Lastly, ways to improve analytic modeling of predicting vortex-induced vibrations were found by finding the best model for a given situation. This was done using two classical design models and a newly approximated model and the best predictive model was found to depend on the product of mass and damping. When this product was low, the newly approximated model worked best while one of the design models was better when the mass-damping product was high.Les vibrations causées par le détachement de tourbillons alternés (vibrations induites par vortex) constituent une préoccupation majeure lors de la conception de cheminées industrielles. Cette excitation est due à un couplage non linéaire entre le lâcher tourbillonnaire et le mouvement d’oscillation. Elle peut engendrer des amplitudes de vibration élevées à faible vitesse de vent. Il existe de nombreuses méthodes pour les prédire et la plupart d'entre elles doivent être améliorées.Pour améliorer les prédictions en soufflerie, il est nécessaire de connaître l'écoulement autour des cylindres circulaires à des nombres de Reynolds élevés. Une expérience dans une grande soufflerie a révélé une nouvelle information concernant la fréquence de lâcher des tourbillons à grands nombres de Reynolds : au lieu d'une seule fréquence, nous avons trouvé deux nombres de Strouhal bien distincts, 0.2 et 0.25 environ. Or de nombreuses études antérieures avaient trouvé des nombres de Strouhal dispersés dans l'intervalle 0.2-0.25 sans plus de précision.De plus, les distributions de pression instationnaire et les mesures de force à grande échelle sont utilisées pour valider une méthode expérimentale pour simuler un écoulement à haut nombre de Reynolds dans une soufflerie à petite échelle. Des éléments de rugosité collés sur la surface peuvent déclencher un écoulement à nombre de Reynolds élevé et reproduire en grande partie les distributions de pression instationnaire. Néanmoins, les fréquences de lâcher de tourbillons et les efforts restent différents à petite échelle.Dans des essais aéroélastiques 3D, on trouve que la couche limite atmosphérique turbulente affecte davantage l'écoulement que les rugosités artificielles. Sans couche limite atmosphérique, la réponse augmente et diffère entre le cylindre rugueux et le cylindre lisse. Ces résultats ont été corroborés par une expérience vraie grandeur sur site avec des profils de couche limite variant naturellement.Une autre méthode pour prédire les vibrations induites par les tourbillons consiste à utiliser des modèles analytiques. Pour trouver le meilleur modèle, deux modèles classiques sont comparés à un nouveau modèle approximatif. Les résultats dépendent du produit masse-amortissement. Lorsque ce produit est faible, le nouveau modèle fonctionne mieux, tandis que l'un des modèles classiques reste meilleur lorsque ce produit masse-amortissement est élevé
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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