1,721,033 research outputs found
Corrosion protection of sintered metal parts by coating deposition. Part II: corrosion and electrochemical characterization
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Comparison of organic coatings accelerated tests and natural weathering considering meteorological data
No full textThe protective properties of organic coatings for outdoor applications are generally evaluated by means of accelerated laboratory tests, including electrochemical techniques. The coatings are stressed by different mechanical, chemical, thermal loads and the effects on the protective properties can be measured by using well established electrochemical techniques, like electrochemical impedance spectroscopy, electrochemical noise, etc. An open question is how these accelerated tests can be correlated with natural exposure in different environments. It is well known that many papers did not find any significant correlation between the natural exposure and different laboratory tests. This fact is due to many reasons, but one aspect very important is that the natural exposure is generally not sufficiently defined. The time of exposure (and the season) in a natural site is not sufficient to define the weathering, being the meteorological conditions variables considering different years. In this paper we proposed a new different approach. The starting point is a very simple consideration. We can try to define the natural weathering by considering a few different environmental parameters affecting the organic coatings properties: total amount of energy coming from UV radiation, time with relative humidity higher than a defined threshold (causing surface water condensation), environmental temperature higher that the polymer Tg, temperature range, etc. In this way, by carefully monitoring these parameters, it is interesting to verify if a correlation exists with some artificial accelerated tests (UV exposure, thermal cycling, salt spray chamber, etc.). This paper is a first attempt to apply this approach to a polyester coil coating for outdoor application. We considered different times of natural exposure in Trento (alpine region, north of Italy), monitoring at the same time all the meteorological parameters. The same coatings were tested in the laboratory using electrochemical impedance spectroscopy, in order to quantify the damage, after some different accelerated tests: thermal cycling, salt spray chamber and UV exposures. The results were compared with the impedance data measured after natural exposure and a correlation was investigated between the sum of the "natural stresses" and the sum of the "artificial stresses". The first results are very interesting and encouraging future work using the same approach on different materials and comparing several natural sites of exposur
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
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