1,721,067 research outputs found
Turbulent drag reduction via oblique travelling waves
No full textLAUREA MAGISTRALEQuesto lavoro descrive la risposta di un flusso turbolento in un canale piano ad onde sinusoidali di velocità spanwise imposte alle pareti. Tali onde viaggiano lungo direzioni comprese tra quelle streamwise e spanwise, e costituiscono pertanto onde viaggianti oblique. I due casi estremi sono già stati studiati rispettivamente da Quadrio et al. (J. Fluid Mech., 627, 2009) e Zhao et al. (Fluid Dyn. Res., 34, 2004). Il lavoro di Quadrio et al. è ad oggi considerato come rappresentativo di una delle strategie in anello aperto più promettenti per la riduzione della resistenza turbolenta di attrito.
L'effetto del cambio della direzione di propagazione delle onde in termini di riduzione di resistenza e le conseguenti potenzialità di risparmio energetico netto sono stati studiati attraverso simulazioni numeriche dirette (DNS). E' stata condotta una campagna parametrica per indagare tutto lo spazio dei parametri: l'ampiezza A, la frequenza w e le componenti streamwise e spanwise del numero d'onda kx e kz. Per mantenere i costi computazionali contenuti, è stato impiegato un dominio di calcolo di dimensioni ridotte.
I risultati ottenuti con più di 2000 DNS rivelano che, per qualunque ampiezza, il forzamento ottimale, sia in termini di riduzione di resistenza e guadagno energetico netto, è quello con kz=0. In altre parole, non è possibile ottenere prestazioni migliori di quelle ottenute dalle onde viaggianti in direzione streamwise descritte da Quadrio et al.The present study describes the response of a turbulent channel flow to sinusoidal travelling waves of spanwise velocity applied at the walls. The waves travel along oblique directions between the streamwise and the spanwise extrema, resulting in: oblique travelling waves. These boundary phenomena have been studied by Quadrio et al (J. Fluid Mech., 627, 2009) and Zhao et al. (Fluid Dyn. Res., 34, 2004) respectively. The former is nowadays considered as one of the most promising open-loop strategies for turbulent skin-friction drag reduction.
The effect of the travel direction of the waves upon the drag reduction and the consequent net energy savings has been studied through Direct Numerical Simulations: a parametric campaign has been carried out in order to investigate the whole parameter space, by simultaneously changing: the amplitude A, the temporal frequency w and the streamwise and spanwise wavenumber components kx and kz. The results from more than 2000 DNS assess that, at any amplitude, the optimal forcing, either in terms of drag reduction and net energy saving, is always the one with kz =0. In other words, it is not possible to improve above the performance produced by the streamwise-travelling waves described by Quadrio et al
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
Coupling heterogeneous continuum-particle fields to simulate non-isothermal microscale gas flows
No full textThis data folder contains the direct simulation Monte Carlo (DSMC) case directories and data generated from multiscale and full-DSMC simulations.The DSMC simulations use the standard folder and file format of OpenFOAM; see www.openfoam.org for more information on how cases are setup, how to use the dictionaries (i.e. the input files) etc.
Formats in this data-share folder:
* .sh linux execution scripts
* .mat, .m matlab files
* .eps images
* .gp gnuplot batch scripts (for producing images)
All other files (including those that do not contain an extension) are text files and can be viewed using standard text editors.
The zip file 'HighSpeedCouette.zip' contains data for the section of the paper: "1D validation: high-speed micro Couette flow" in the following folders:
* Full DSMC validation case: FullDSMCCouette
* Multiscale simulations: Pi=2 Pi=3 Pi=4
* Gnuplot post-processing scripts: GnuplotPostProc_Combined
The zip file 'TwoDimensionalCrack.zip' contains data for the section of the paper: "2D validation: flow through a microscale crack-type geometry" in the following folders/files:
* Full DSMC validation case: FullDSMCCrackTempGradX.zip
* Multiscale simulation (subdomain cases and matlab scripts): Kn1_crackProblemTempGradXBulk
* Gnuplot post-processing scripts: GnuplotPostProc.zip
* Back-up storage of data array elements produced by matlab scripts for the multiscale simulation: matlabScript
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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