1,720,963 research outputs found
Assessment of subgrid dispersion models for large-eddy simulations of turbulent jet flows with dilute spray droplets
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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
A thermal flash-boiling model for secondary atomization of Lagrangian droplets
No full textFlash-boiling occurs when super-heated liquid are injected in an environment whose thermodynamic conditions are below the saturation level. In combustion devices, this phenomena can be helpful to obtain a rapid vaporization of the fuel immediately after the injection. From the modeling standpoint, flash-boiling breakup is interpreted as a sequence of events that can be heuristically modeled. This manuscript aims at proposing an heuristic model that involves nucleation of multiple bubbles inside the droplet and their thermally-driven growth. The a priori validation shows that the Blander and Katz nucleation model with the full chemical potential decently predict the nucleation temperature in an ammonia droplet and the Mikic growth model coupled with a proposed temperature equation for the internal heat transfer captures the bubble radius growth of different water bubbles. From a simulation of an ammonia droplet explosion with OpenFOAM, the children droplet temperature is also well predicted. The time scales analysis revealed the region of applicability of the model, allowing a consistent reduction of computational cost
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
Study on buoyant instabilities of high pressures laminar jet flames
No full textLaminar diffusion jet flames are subjected to buoyant instabilities when the Froude number is lower than a critical value. In the present work, a numerical study on syngas laminar jet diffusion flames at elevated pressures (1, 2, 4, 8 and 12 bar) and buoyant instabilities is presented. Since the Reynolds number is kept constant, the velocity and Froude number diminish as pressure is increased. For pressures from 1 to 4 bar the flames display a steady behavior with a progressive reduction of the thickness, while for 8 and 12 bar the flames oscillate and pulsate. These predictions are consistent with experimental observations. Furthermore, for the unsteady flames, the pulsation of the flame thickness and spatial oscillations are quantified and analyzed
Analysis of Wall–flame Interaction in Laminar Non-premixed Combustion
No full textThe study is aimed at demonstrating a methodology for the time-scale characterization of the chemistry-wall-heat-transfer interaction. The driving chemical time-scale is estimated by means of the tangential stretching rate, and a proper thermal timescale for the temperature-time variation due to wall heat flux is presented. A thermal Damköhler number, Dath, is proposed as the ratio of the two. The methodology is applied on a prototypical laminar methane-oxygen diffusion flame impinging on an isothermal cold wall. Non-adiabatic effects are described qualitatively and a CSP-TSR analysis is performed to obtain topological information and physical insights. The thermal Damköhler number field is computed and discussed to highlight the interplay between chemical and diffusive processes and to a-priori assess the accuracy of the steady laminar flamelet assumption under non-adiabatic conditions
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