1,721,036 research outputs found
Dissolution or Growth of a Liquid Drop Embedded in a Continuous Phase of Another Liquid via a Phase-Field Ternary Mixture Model based on the NRTL (Non-Random Two Liquid) equation.
No full textWe simulate the diffusion-driven dissolution or growth of a single-component drop embedded in a continuous phase of a binary liquid (or viceversa). Our theoretical approach follows a phase field model of partially miscible ternary liquid mixtures, which is based on a regular solution assumption together with a Cahn-Hilliard representation of the nonlocal components of the Gibbs free energy of mixing. In addition, the excess free energy is modeled with either a Flory-Huggins or an NRTL model equation. Based on 2D simulation results, we show that for a single-component drop embedded in a continuous phase of a binary liquid (which is highly miscible with either one component of the continuous phase but immiscible with the other) the size of the drop can either shrink to zero or reach a stationary value, depending on whether the global composition of the mixture is within the one-phase region or the unstable range of the phase diagram. Similar results are obtained in the case of an isolated two-component drop embedded in a continuous phase of a single-component liquid. Finally, we show that the results obtained using the two excess free energy models are virtually identical to each other
Phase separation of initially inhomogeneous liquid mixtures
No full textIn previous works, we showed that the spinodal decomposition of low-viscosity liquid mixtures is driven by the convection induced by chemical potential gradients. In this article, we study the impact of this driving force on the phase separation of low-viscosity liquid mixtures in which a strong initial concentration gradient is present within a few-millimeter-thick layer. This region was created by keeping an initially demixed mixture at a higher-than-critical temperature for 0.5 h and allowing it to mix by diffusion. After a deep and rapid quench within the spinodal range, the mixtures at first remained macroscopically unchanged; then micron-sized drops appeared; and finally, after few seconds, a sharp interface suddenly formed, with droplet sizes never exceeding 10 μm. As it took hours for diffusion and only seconds for phase separation, this result shows that the latter process cannot be driven by diffusion. This conclusion was reinforced by adding glass particles to the mixture and observing the velocity pattern, which had speeds exceeding 0.5 mm/s, thus demonstrating that the process is driven by convection. The impact of gravity was ruled out, as the morphology of a density-segregated mixture as it phase separates appears to be the same as that of an isodensity mixture. These effects can be explained considering that the large initial concentration gradient induces a body force that drives small drops toward one or the other of the homogeneous phases, where they are rapidly reabsorbed, thus explaining why larger drops were not observed during the separation process. In addition, the measured bulk velocities correlate with the magnitude of the chemical potential gradients, in agreement with the theoretical model
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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