1,720,963 research outputs found
Trailing edge serrations effects on the aerodynamic performance of a NACA 643418
No full textA study of the aerodynamic performance of a NACA 643418 airfoil with trailing edge serrations is presented. For the prediction of the changes in lift due to the serration installation, an empirical law is derived that can be extended to typical cambered airfoils for wind turbine applications. The law is deduced from 2D and 3D Reynolds‐averaged Navier–Stokes simulations (RANS) of the flow over the airfoil. Lift and drag together with the changes in the wake flow due to the presence of the serrated edges are investigated. An additional study of the sensitivity of the results at Rec = 3·106 with respect to the turbulence modeling is carried out by using three different RANS models: Spalart–Allmaras, k‐omega SST, and Transition SST. Results show that the changes in lift due to trailing‐edge extensions are approximated by the effect of a split plate with reduced length.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
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
Serrations effect on the aerodynamic performance of wind turbine airfoils
No full textA numerical and experimental analysis of the trailing edge serrations effect on the aerodynamic performance of the NACA643418 airfoil is presented. 3D Reynolds-averaged Navier-Stokes simulations (RANS) of the flow over the airfoil with and without trailing edge serrations have been carried out with the Transitions SST turbulence model. From these calculations an empirical law for the prediction of the aerodynamic behaviour of the airfoil with serrations is derived. The law is validated through wind tunnel experiments. The NACA643418 airfoil has been tested with trailing edge serrations installed with different flap angles to analyze the effect of the parameter on the performance of the airfoil. Results show that the trailing edge serrations cause a significant increment in lift coefficient with low penalties in drag.Wind Energ
Trailing-edge serrations effect on the performance of a wind turbine
No full textAn experimental study focusing on the change of the aerodynamic performance of a wind turbine with the employment of trailing-edge serrations is presented. The design procedure which starts from the serration design, together with the experimental wind tunnel testing and the installation in an already operating wind turbine is discussed. A prediction methodology to estimate the aerodynamic performance change of the machine with the blade add-on is validated by in-field measurements. Wind tunnel experiments for the validation of the original serration design have been carried out on a Nordex ADO30 airfoil with a relative thickness of 30% and on a NACA643418 airfoil with 18% thickness. The two airfoils are respectively used in this study due to their peculiar characteristics. While the first has been designed for relatively high Cl/Cd performance versus structural integrity (i.e. relatively high thickness), the second one is a typical reference airfoil used in wind turbines for its interesting Cl/Cd performance in both laminar and rough conditions. Clean and rough conditions have been tested in order to prepare a database for the analysis of the full turbine in several wind conditions. Aerodynamic forces with the serrated trailing-edge extensions are measured for different angles of attack and serration flap angles. The results are further discussed and employed for the analysis of the full rotor. Results already show that an increase in the flap angle is typically associated with an increment in lift, but not necessarily in drag. This has a beneficial effect on the operational regime of the machine when taken into account. The influence of the trailing-edge serrations on an operating wind turbine has been quantified in terms of total loads and energy production. The power curves with and without the trailing-edge installations are further analyzed and compared with the theoretical predictions. • Experimental tests show big impact of serrations on airfoil's aerodynamic properties • Predictive law used for extending the serrations influence to the whole blade • Theoretically, serrations have positive impact on power production of wind turbines • Theoretically, serrations increase wind turbine loads and reduce its life-time • Positive impact of serrations on power production of real machines has been probedGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
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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