1,720,964 research outputs found
Experimental characterization of nanofluids as heat transfer media
Full text linkNanofluids are formed by solid particles with nano-sized dimension (1-200 nm) dispersed into common fluids. From the beginning, they have been proposed as heat transfer media, considering the high thermal conductivity of solid nanoparticles compared to the inherently poor thermal properties of conventional heat transfer fluids. In the last years, an exponential increase of publications on nanofluids is occurred. However, nanofluids are complex fluids, literature experimental works are often controversial and theoretical investigations must to be deepened. A big issue concerns the production of stable and reliable fluids, since different nanoparticles can be prepared with different methods and, also, different nanofluids derive from different preparation techniques.
In this work, nine nanofluids were analysed. The stability of the suspension was evaluated considering the mean size distribution of nanoparticles in suspension using the DLS technique. In addition, the ζ potential and the pH of the nanofluids were measured for the stability analysis. For stable nanofluids, the study of the thermophysical properties is necessary to understand their energy behaviour. Therefore, thermal conductivity and dynamic viscosity were determined experimentally.
The final objective of this work is to investigate the convective heat transfer capabilities of nanofluids. For this purpose, an experimental apparatus was built in order to measure the convective, single phase heat transfer coefficient of nanofluids, at constant wall heat flux.
After an intense work of experimental measurement on several nanofluids, a nanofluid with extraordinary thermophysical properties was not found, in spite of some results published in the literature. Amongst all the studied suspensions, it seems metal nanoparticles are the most promising. More concentrated nanofluids, with the proper surfactants, are under study
Nano-PCMs for enhanced energy storage and passive cooling applications
No full textIt is well known that the heat transfer associated with a phase change process is much higher than sensible enthalpy change even in forced convection. In particular, the vaporization process has been widely studied because it exploits the highest heat transfer coefficient; this heat transfer mechanism is used in both passive (i.e. heat pipes) and active (i.e. refrigerating machines) cooling devices. However, the solid liquid phase change process is another interesting possibility to reject even high heat loads, especially when they are intermittent. The term Phase Change Materials (PCMs) commonly refers to those materials, which use the solid-liquid phase change process to adsorb and then release heat loads (Mancin et al., 2015). The present work aims at investigating the feasibility of a new challenging use of Aluminum Oxide (Al2O3) and Carbon Black (CB) nanoparticles to enhance the thermal properties: thermal conductivity, specific heat, and latent heat of pure paraffin waxes to obtain a new class of PCMs, the so-called nano-PCMs. The nano-PCMs were obtained by seeding 1 wt% of nanoparticles in paraffin waxes with melting temperatures of 20 C and 25 C. The thermophysical properties were then measured to understand the effects of the nanoparticles on the thermal properties of both the solid and liquid PCM. These new nano-PCMs can represent a feasible and interesting way to mitigate or eliminate the intrinsic limitations in the use of paraffin waxes as PCMs for both energy storage and passive cooling applications
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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