1,721,037 research outputs found
Corrosion Resistance of 3D-Printed and Conventional Die Steels in Contact with Molten Aluminum Alloys
No full textThis study investigates the corrosion resistance of maraging steel produced via additive manufacturing and conventional forging when exposed to molten aluminum alloys used in high-pressure die casting (HPDC). The H11 tool steel, typically used in such applications, was also studied for comparison. Static immersion tests were conducted in three different aluminum alloys for HPDC (AlSi7Mg, AlSi10Mg, AlSi10MgFe). SEM-EDS analysis revealed differences in the formation of intermetallic layers on the metallic surfaces, mainly depending on the material considered. The laser-power bed fused maraging steel, often used for conformal cooling inserts, exhibited the formation of a stable high Fe intermetallic layer without a liquid phase, contributing to superior corrosion resistance compared to the forged maraging steel. The H11 tool steel demonstrated the highest corrosion resistance, especially due to its composition free from Ni and the presence of Cr and Cr-carbide. Thermo-Calc equilibrium simulations identified the phases present in the intermetallic layers at the test temperature, highlighting the effects of different steel compositions on interfacial intermetallic layers. These findings underline the critical role of manufacturing processes and alloy composition on the performance of steels in contact with molten aluminum alloys, with implications for die casting applications
Urban air pollution and children respiratory hospital admissions in Pisa (Italy) a time series and a case-crossover approach
No full textObjectives: we evaluated the association of daily pollutants’ concentrations with daily hospital admissions for respiratory causes in children residents in Pisa during 1998-2002. We compared the results obtained with two methods of statistical analyses. A total of 657 children under ten years and admitted to local hospitals for respiratory diseases (ICD 9: 460-469, 480- 519) were included in the study. Design: both time-series and case-crossover analysis were applied, controlling for temperature, holidays, influenza epidemics, rain and relative humidity. Pollutants’ effects are expressed as percentage increase (and 95% CI) of hospital admissions for an increase of 10 μg/m3 of pollutants (1 mg/m3 for CO). Results: with both analyses, children’s hospital admissions for respiratory conditions were significantly associated to increasing daily levels of PM10 and CO at different time lags, while no association was found for NO2 and O3. In the case-crossover analysis, for a daily increase of 10 μg/m3 in PM10, a significant increment of 8.5% (CI 95% 0.02; 17.6) in children respiratory admissions was observed at lag 0-3. Results were stronger for males and during the warm season. A 1 mg/m3 increment in daily CO levels was associated with an increase of respiratory admissions at lag 0 (20.2%, CI 95% 5.3; 37.2) and at all cumulative lags: the maximum value was observed at lag 0-3 (32.6%, CI 95%8.3; 62.2). Time series analyses provides similar results, although the estimates were lower than with the other method, in terms of percentage increment and length of confidence intervals. Conclusions: this study indicates adverse effects of air pollution on respiratory health of children living in urban environment. The results of both analyses were consistent
Ricoveri Ospedalieri per cause respiratorie nei bambini e monossido di carbonio: approccio con analisi temporali e case-crossover
No full text
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
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