1,720,972 research outputs found
Numerical simulation of two-dimensional blade-vortex interactions using unstructured adaptive meshes
No full textA two-dimensional Euler flow solver has been developed for the simulation of unsteady, blade-vortex interaction problems on unstructured meshes. The Euler solver is based on a second-order-accurate implicit time integration using a point Gauss-Seidel relaxation scheme and a dual time-step subiteration. A vertex-centered, finite volume discretization is used in conjunction with the Roe's flux-difference splitting. An unsteady solution-adaptive dynamic mesh scheme is used by adding and deleting mesh points at every adaptation step to take account of not only spatial but also of temporal variations of the flow field. Unsteady flow around a harmonically oscillating airfoil and traveling vortex in a freestream were simulated to validate the accuracy of the dynamic mesh adaptation procedure. Three blade-vortex interaction problems, two at transonic freestream speeds and one with vortex-airfoil collision, were investigated. Computed results show good agreements with existing experimental and computational results within the accuracy of the present inviscid solver. It is found that the evolution of vorticies and propagation of acoustic waves can be accurately simulated using the present unstructured dynamic mesh adaptation procedure
Time-accurate Navier-Stokes simulation of vortex convection using an unstructured dynamic mesh procedure
No full textA two-dimensional Navier-Stokes flow solver is developed for the simulation of unsteady flows on unstructured adaptive meshes. The solver is based on a second-order accurate implicit time integration using a point Gauss-Seidel relaxation scheme and a dual time-step. subiteration. A vertex-centered, finite-volume discretization is used in conjunction with Roe's flux-difference splitting. The Spalart-Allmaras one equation model is employed for the simulation of turbulence. An unsteady solution-adaptive dynamic mesh scheme is used by adding and deleting mesh points to take account of spatial and temporal variations of the flowfield. Unsteady viscous flow for a traveling vortex in a free stream is simulated to validate the accuracy of the dynamic mesh adaptation procedure. Flow around a circular cylinder and two blade-vortex interaction problems are investigated for demonstration of the present method. Computed results show good agreement with existing experimental and computational results. It was found that unsteady time-accurate viscous flows can be accurately simulated using the present unstructured dynamic mesh adaptation procedure. (C) 2002 Elsevier Science Ltd. All rights reserved
Technical note numerical simulation of fluid-structure interaction under two-dimensional BVI
No full textThe fluid-structure interaction of an airfoil under two-dimensional inviscid blade-vortex interaction (BVI) was numerically studied using an unstructured mesh flow solver. The flow solver was based on a vertex-centered finite-volume method and an implicit point Gauss-Seidel relaxation scheme. The accuracy of solution is enhanced by adopting a multi-level solution-adaptive dynamic-mesh technique. The aeroelastic behavior of the airfoil is predicted by coupling the flow solver with an idealized two degree-of-freedom spring system. The effect of BVI on the aeroelastic displacement of a stationary airfoil and an airfoil oscillating at a neutral flutter velocity is investigated. Interaction of travelling vortex with an airfoil under forced harmonic oscillation is also studied. The results are compared with those of an airfoil without BVI and without motion
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
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
- …
