1,721,408 research outputs found
The Influence of Processing Parameters on the Al-Mn Enriched Nano-Precipitates Formation in a Novel Al-Mn-Cr-Zr Alloy Tailored for Power Bed Fusion-Laser Beam Process
Full text linkAmong the recently developed compositions tailored for the power bed fusion-laser beam process (PBF-LB), the novel Al-Mn-Cr-Zr alloy stands out. This composition exploits high solid solution strengthening, achieving a high hardness value in the as-built condition. The produced samples are inherently crack-free and have a good level of densification (similar to 99.5%). The goal of this study is to investigate how this quaternary system is affected by the laser power while retaining a similar volumetric energy density. A comparison between the microstructural features and the mechanical performance was performed on a set of samples processed with power values ranging from 100 to 170 W. Microstructural features were investigated through optical microscopy, Electron Back Scattered Diffraction (EBSD) investigation and feature analysis using advanced microscopy to examine the amount, distribution, and shape of precipitates in the different process conditions. Although the quantitative feature analysis permitted analysis of more than 60 k precipitates for each power condition, all samples demonstrated a low level of precipitation (below 0.3%) with nanometric size (around 75 nm). The mechanical performances of this quaternary system as a function of the laser power value were evaluated with a microhardness test, recording very similar values for the different process conditions with a mean value of approximately 104 HV. The results suggested a very stable system over the tested range of process parameters. In addition, considering the low level of precipitation of nanometric phases enriched in Al-Mn, a supersaturated state could be established in each process condition
Influence of friction models on FE simulation results of orthogonal cutting process
No full textIt is well-known that the reliability of finite element
(FE) simulation results of cutting processes depends mainly
on two factors: implementation of a well-defined constitutive
model which can properly represent the severe deformation in
chip formation process as well as the viability of the relation
adopted to simulate the frictional condition at the tool-chip
interface. In the current study, a systematic approach is presented
to evaluate the performance of various friction models
in three different FE commercial codes: Deform 2D, Abaqus/
Explicit and AdvantEdge. The frictional condition was
analysed for two uncoated cemented carbide-plain carbon
steel combinations: K10/AISI 1045 and H13A/AISI 1080.
The results indicated that approximately similar ranges of
minimum average error in simulation responses can be
achieved, independently of the FE code used for simulation
of the chip formation process and for both tool-work material
combinations
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
The effect of powder reuse on the surface chemical composition of the Scalmalloy powder in Powder Bed Fusion – Laser Beam process
Full text linkThe powder quality is one of the main factors to be considered in laser powder bedfusion (PBF-LB/M) production closely connected with the performance of the finalcomponent. Only powders with spherical particles, a low percentage of satellites, anarrow particle size distribution, controlled internal defects and a strongly limitedsurface oxide layer are acceptable for PBF-LB/M production. Gas atomisation is themain production method that permits to achieve the restrictive standards of thePBF-LB/M powder; however, it is energy-intensive and characterised by limited pro-ductivity. These considerations justify the key role of the reuse of the unmeltedmetal powder in obtaining a more sustainable PBF-LB/M process. Nevertheless, thereuse of the powder leads to significant changes in the particle morphology, particlesize distribution and surface chemical composition, which can compromise the bulkproperties. Powder surface oxide is one of the most impactful problems for the PBF-LB/M production, and Al-based alloys are particularly prone to this phenomenon.With the aim to study the effect of the powder reuse, a surface chemical analysis ongas atomised Scalmalloy powder was performed through the X-ray photoelectronspectroscopy investigation before and after seven jobs with 32 h as overall buildtime. Results obtained for virgin and recycled Scalmalloy powders revealed remark-able differences in depth and composition of the surface oxide layer. The 57%increase in the oxide layer thickness and the formation of carbides during PBF-LB/Mproduction can have harmful effects on bulk properties
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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