1,720,959 research outputs found
Efficient optimization framework for L-PBF fatigue enhanced Ti6Al4V lattice component
Get PDFIndustries today face challenges in incorporating metallic additively manufactured lattice structures in critical components subjected to fatigue loading. This work explores the relationship between fatigue properties and the printing orientation of Laser-Powered Bed Fusion (LPBF) lattice structures. This relation is at the base of a cost-effective and time-efficient optimization workflow able to determine the optimal lattice printing orientation for improved fatigue life. Fatigue resistance is tested under uniaxial conditions on miniaturized specimens that mimic the lattice sub-unit elements: struts and nodes. The collected data is used as input for the optimization algorithm to determine the specimen orientation that maximizes fatigue life. The optimized specimens are manufactured, tested under three-point-bending conditions, and analysed using metrological x-ray computed tomography to verify the improvement. The proposed workflow is able to produce a 24 % increase in specimen fatigue life by simply adjusting the orientation on the printing plane
Comparative metrological characterization of Ti6Al4V lattice structures produced by laser powder bed fusion
No full textThe advancement of Additive Manufacturing (AM) technologies, such as Laser Powder Bed Fusion (LPBF), enables the fabrication of metallic lattice materials with a wide range of topologies and size scales. The possibility to manufacture these materials into complex shapes with good property-to-weight ratio stimulates a growing interest in several industrial sectors, including biomedical, aerospace, and automotive. Nevertheless, such structural features printed at a small-scale often suffer from a wide range of morphological defects that can lead to a marked deviation from the nominal geometry and consequently impact the mechanical, transport and thermal properties. An accurate metrological characterization of the lattice is thus of paramount importance for a more reliable prediction of the properties of the lattice.
The most common characterization techniques used for as-built lattice materials are scanning electron microscopy (SEM), optical microscopy (OM) and X-ray computed tomography (CT). CT, contrary to the other methods, provides full 3D data including inaccessible geometries and features, in a non-destructive way, but it requires expensive equipment and considerable expertise. SEM and OM can be faster and less expensive, but can be non-destructive only when limited to the outer surface of the lattice. When combined with metallographic analysis, instead, they require destructive, careful and time-consuming specimen preparation, and the analysis is confined to selected sections.
In this work, the three above-mentioned techniques are applied to the metrological characterization of LBPF Ti6Al4V regular cubic lattices of 4 mm unit cell size and struts with circular cross-section of diameter 0.760 mm. The results in terms of strut cross-section parameters and junction fillet radius are compared and the effect of the size of the analysis domain on the accuracy of the results is investigated by comparing lattice sub-volumes of different size. Via a thorough statistical analysis it is shown that CT and metallographic characterization are compatible, while microscope imaging can lead to an overestimation of the strut thickness
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
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
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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