1,720,955 research outputs found
Remarks on time dependent periodic Navier-Stokes flows on a two-dimensional torus
No full textThis note is a continuation of the earlier paper [Chen, Z. M., Price, W. G.: Time dependent periodic Navier–Stokes flows on a two-dimensional torus. Commun. Math. Phys. {\bf 179}, 577–597 (1996)], where the evidences of the occurrence for the time dependent periodic Navier–Stokes flows were found based on a combination of analysis and computation. This investigation is now confirmed via rigorous analysis. The existence of the time dependent periodic Navier–Stokes flows on a two-dimensional torus is prove
Turbulence and energy dissipation mechanisms in steady spilling breaking waves induced by a shallowly submerged hydrofoil
No full textWave breaking is one of the most violent phenomena in air-water interface interactions that need to be considered in ship and offshore structures design. Spilling breaking waves induced by a shallowly submerged hydrofoil are investigated using a Navier-Stokes solver for two-phase flow. Computed wave profiles and velocity fields are compared with experimental results and good agreement obtained. A related non-breaking wave case is designed based on the same numerical model to distinguish the hydrodynamic characteristics of the spilling breaking waves and allow investigation of effects on waves downstream. The velocity profile and turbulence intensity profiles at different sections from the two cases are compared with measurement data, where available. A detailed comparison of the wave-breaking process compared to the non-breaking wave is provided. Further, the energy dissipation processes for the two cases are analyzed and the ratio of the turbulent dissipation rate to the total energy dissipation calculated. It is shown that a large amount of energy is dissipated in the region of the breaking wave when compared to the non-breaking wave. Approximately 12% of the total energy dissipation may be attributed to the wave-breaking process, induced by energy redistribution and additional contributions to turbulent fluctuations in the breaker
Performance of a two-phase flow solver for the simulation of breaking waves
No full textWave breaking is one of the most violent phenomena observed in air-water interface interactions. This phenomenon commonly occurs in real ship flows and is one of the main sources of underwater noise and white-water wakes. The investigation of this phenomenon is thus important in ship and ocean engineering. The performance of a two-phase flow solver is investigated for a simulation of spilling breaking waves generated by a shallowly submerged hydrofoil (NACA0024) in a uniform flow. An algebraic Volume of Fluid (AVOF) method is applied to capture the dynamic behaviour of the free surface and a standard k - ε turbulence model is selected to capture the turbulent flow around and downstream of the hydrofoil. The wave profiles, pressure and velocity contours are computed to investigate the overall flow conditions and a detailed analysis of the flow field downstream of the hydrofoil is conducted in terms of velocity components and turbulence intensities at six measurement sections. A comparison of the numerical and experimental results shows that an accurate representation of the free surface and the turbulent flow beneath it is obtained with the present numerical scheme. It is expected that the systematic documentation of the performance of the AVOF two-phase solver will enable its more accurate and optimal use for simulating ship-related flows, as well as increase awareness of its potential shortcomings for those interested in general CFD simulation of breaking waves
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
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
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