1,720,956 research outputs found
The corrosion resistance of maraging steel 1.2709 produced by L-PBF in contact with molten Al-alloys
No full textNowadays there is a growing interest in the use of secondary Al-alloys for high-pressure die casting to obtain structural parts. To guarantee appropriate performance, these alloys are characterized by a lower Fe content (< 0.15%) than conventional secondary ones, commonly used in the production of non-structural parts. This makes them more susceptible to the phenomenon of die-soldering, thus resulting in a decrease in the service life of dies and inserts. The production of complex and demanding castings requires appropriate dies and materials, especially in high stressed areas where higher-performance steel inserts are used. Recently, maraging steel has been applied for these issues. Thanks to the good weldability of maraging steels, these alloys are nowadays also processed by additive manufacturing (AM) techniques, to obtain very complex parts like inserts with conformal cooling channels, able to extend the life of the inserts themselves, increasing productivity. In this context, this work aimed at the evaluation of the dissolution of maraging steel (1.2709) samples obtained via laser-based powder bed fusion (L-PBF) into molten AlSi7Mg (B356.2) through static immersion tests carried out at 720 °C for different times, to evaluate their response to the die-soldering phenomenon. For comparison, forged maraging steel samples were also considered, to investigate the effect of the different microstructure on the dissolution behavior. As well as a conventional H11 steel, to obtain benchmark data. The corrosion resistance of the samples was evaluated by measuring the samples' dimensional variation after the tests. Furthermore, SEM-EDS analysis was carried out to investigate the extent and the composition of the intermetallic layer formed on the samples' surface
Wear Behavior of AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion and Gravity Casting
Full text linkHerein, the sliding wear behavior of AlSi10Mg samples realized using laser-based powder bed fusion (LPBF) is investigated via pin-on-disc (PoD) tests, before and after T6 heat treatment. The changes in the microstructure, density, and hardness induced by heat treatment are correlated with the tribological behavior of the alloy. Furthermore, short wear tests are conducted and the resulting wear tracks are investigated through scanning electron microscopy (SEM), equipped with an energy-dispersive spectroscopy (EDS) microprobe to elucidate how the wear mechanisms evolve with sliding distance. For comparison, gravity cast (GC) AlSi10Mg samples are also characterized and tested. The as-built additive manufacturing (AM) sample exhibits the lowest wear rate and coefficient of friction because of its high hardness and relative density, whereas the heat-treated sample shows the worst behavior in comparison with the GC samples. The results suggest a significant influence of porosity on the wear behavior of AM alloys
Wear Behavior of Nb Alloyed Gray Cast Iron for Automotive Brake Disc Application
Full text linkGray cast iron (GCI) with a pearlitic matrix and type-A graphite remains the most widely used material in the manufacturing of brake discs. To reduce the environmental impact of disc wear during braking, alternative materials and/or compositions to the standard ones are being studied. In this study, the effect of variation in niobium content (0–0.7 wt%) on microstructure and wear behavior of samples machined from brake discs made of hypoeutectic gray cast iron was investigated. The wear behavior of GCI was examined through pin-on-disc (PoD) wear tests using low-metallic-friction material discs as the counterparts. Microstructural analyses and hardness measurements were also conducted to evaluate the effect of Nb addition on the morphology of graphite, eutectic cells, and distribution of carbides. In addition, the wear mechanisms of different samples were evaluated using scanning electron microscope analysis. The results revealed that adding 0.3% of Nb promotes the highest wear resistance of the alloys
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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