1,721,027 research outputs found
LES and hybrid RANS/LES simulation of complex flows on unstructured grids
No full textThe research activity carried out by our group towards the accurate numerical prediction of complex flows is summarized. The large-eddy simulation (LES) and variational multiscale
(VMS) LES approaches are adopted to simulate massively separated, three-dimensional, unsteady
flows. The numerical discretization is based on a mixed finite-element/finite-volume formulation
on unstructured grid. The application of the LES and VMS-LES approaches to the flow around a
square cylinder at a Reynolds number equal to Re = 22000 is presented and analyzed. Furthermore, in order to simulate high Reynolds number flows, a new strategy for blending RANS and
LES approaches in a hybrid model is described. The flow variables are decomposed in a RANS part
(i.e. the averaged flow field), a correction part that takes into account the turbulent large-scale
fluctuations, and a third part made of the unresolved or SGS fluctuations. The basic idea is to
solve the RANS equations in the whole computational domain and to correct the obtained averaged
flow field by adding, where the grid is adequately refined, the remaining resolved fluctuations. To
obtain a model which progressively switches from the RANS to the LES mode, a smooth blending
function is introduced to damp the correction term. Different definitions of the blending function
are proposed and investigated. This approach is applied to the simulation of the flow around a
square cylinder and of the flow around a circular cylinder at Re = 140000. Results are compared
to those of other hybrid simulations in the literature and to experimental data. The sensitivity to
different parameters, such as the blending function definition, the grid refinement and the closure
model for the LES part, is analyzed
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
Quality of classical and variational multiscale LES simulations of the flow around a circular cylinder
No full textThe role of subgrid scale (SOS) viscosity is investigated in LES and VMS-LES simulations of the flow around a circular cylinder at Re = 20000 on unstructured grids. The separation between the largest and the smallest resolved scales in the VMS formulation is obtained through a variational projection operator and finite-volume cell agglomeration. Two different non-dynamic eddy-viscosity SOS models are used both in classical LES and in VMS-LES. The sensitivity of the results to different parameters, such as the value of the SOS model input coefficient or the agglomeration level and to numerical viscosity in VMS-LES, is also addressed. Finally, a possible indicator of quality of the LES and VMS-LES predictions is examined
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
- …
