1,720,957 research outputs found
Experimental and Numerical Investigation on the Electro Hydro Dynamic Interaction generated by a Dielectric Barrier Discharge
No full textA surface dielectric barrier discharge (DBD) actuator has been experimentally investigated. An electrode pair separated by a dielectric sheet constitutes the actuator. Two types of dielectric materials and several a.c. supply conditions have been utilized to generate a surface dielectric barrier discharge with different characteristics. An Electro Hydro Dynamics (EHD) interaction was induced into still air and several fluid-dynamic regimes were obtained. Using electric and fluid dynamics measurements, the energy transfer mechanisms caused by the EHD interaction have been investigated. The visualization of the plasma boundary layer during the discharge ignition phase, characterized by hot vortexes, and during the steady regime has been obtained by means of Schlieren diagnostics technique. Vortex morphology and propagation velocities for both actuator types at all supply conditions have been evaluated. Pitot velocity profiles have been taken in the steady regime operation at several distances along a line perpendicular to the actuator surface. Along this line and as a function of the position the integral of the pixel intensities of the Schlieren image has been calculated. The function obtained matches with a good agreement the Pitot velocity profile for all distances and in all the supply conditions investigated. Numerical simulations were performed to validate theoretically this result. The calculations confirm the relationship between flow velocity distribution in the boundary layer and the gas density distribution
Experimental and Numerical Investigation on a DBD Actuator for Airflow Control, Paper AIAA 2011-3912
No full textA surface dielectric barrier discharge (DBD) actuator has been experimentally investi-gated. An electrode pair separated by a dielectric sheet constitutes the actuator. Two types of dielectric materials and several a.c. supply conditions have been utilized to generate a surface dielectric barrier discharge with different characteristics. An Electro Hydro Dynamics (EHD) interaction was induced into still air and several fluid-dynamic regimes were obtained. Using electric and fluid dynamics measurements, the energy transfer mechanisms caused by the EHD interaction have been investigated. The visualization of the plasma boundary layer during the discharge ignition phase, characterized by hot vortexes, and during the steady regime has been obtained by means of Schlieren diagnostics technique. Vortex morphology and propagation velocities for both actuator types at all supply conditions have been evaluated. Pitot velocity profiles have been taken in the steady regime operation at several distances along a line perpendicular to the actuator surface. Along this line and as a function of the position the integral of the pixel intensities of the Schlieren image has been calculated. The function obtained matches with a good agreement the Pitot velocity profile for all distances and in all the supply conditions investigated. Numerical simulations were performed to validate theoretically this result. The calculations confirm the relationship between flow velocity distribution in the boundary layer and the gas density distribution
Experimental and Numerical Investigation on the MHD Interaction in a Hypersonic Plasma Flow
No full textThe MHD interaction in a hypersonic argon flow was experimentally investigated around a conical test body. The aim of the experiment was to produce a database to be used for the validation of numerical codes for the analysis and simulation of the magnetofluiddynamics in hypersonic flows. This paper summarize the work carried out in the High-Enthalpy Arc-heated hypersonic wind Tunnel of Alta, Pisa, Italy, in cooperation with The Department of Electrical Engineering of the University of Bologna, under the support of The European Space Agency. In the experiments reported, the MHD interaction has been investigated in a Mach 6 ionized argon flow. The experiments has shown a large effect of the MHD interaction on the values of the measured quantities. The experimental results has been numerically investigated. A discussion of the results is presented here
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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