1,720,972 research outputs found
On the use of Structural Nodes Made by Advanced Composite Materials on a Space-Frame Automotive Structures,
No full textFree radical polymerization of unconjugated dienes. 14. Divinyl ketone in acetone solutions at 50°C.
No full textChemical structure and water diffusion in polyester resin-glass fibres composites
No full textThe effect of water on the chemical structure of unsaturated polyester resin-glass fibres composites has been examined for materials of different formulation in the interval of temperature 50-90°C. The major changes in the chemical structure of the material are due to the hydrolysis of terminal chain-segments of the polyester and of polyvinyl acetate (low-profile agent). The latter results in the formation of polyvinyl alcohol with modification of the hydrophilic/hydrophobic balance in the matrix. Other contributing factors in the water sorption behaviour of the material are the leaching of products of polymer hydrolysis, of styrene, of low-molecular weight fillers and additives, and the partial dissolution of ionic species from the glass fibres. Consequent alteration of the thermodynamic and kinetic parameters of water sorption/ desorption have been studied in details. The correlation between the evolving chemical structure of the material and its transport properties allows the development of a diffusion kinetic method to evaluate the properties of polymer composites
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
Morphology analysis of microvoids in SMC: Ageing effects
No full textA quantitative morphological analysis of the porosity in sheet moulding compound (SMC) has been made by using image processing, especially for the microvoids resulting from shrinkage compensation. The first result is that, for the virgin SMC, the microporosity is 5-8% in the external skin of the part and ∼24% in its core. After hydrothermal ageing the microvoids in the core are partially closed again, the total microporosity being reduced to ∼5%. In the skin, the microporosity remains unaffected. Moreover, the size distribution is modified, as the largest microvoids are subdivided into smaller ones. In addition, the morphology of the microvoids has been studied through their fractal behaviour. The characteristic fractal dimension of their complex shape for the virgin material (D = 1.35) becomes Euclidean (D = 1) after ageing. Ageing for 6 and 2570 h and drying indicate the morphology changes to be only partly reversible. In summary, swelling due to water occurs internally, and the irregular shape of the microvoids is smoothed
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
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