1,721,018 research outputs found
Micro-macro relationship between microstructure, porosity, mechanical properties, and build mode parameters of a selective-electron-beam-melted Ti-6Al-4V alloy
Full text linkThe performance of two selective electron beam melting operation modes, namely the manual mode and the automatic ‘build theme mode’, have been investigated for the case of a Ti-6Al-4V alloy (45–105 μ;m average particle size of the powder) in terms of porosity, microstructure, and mechanical properties. The two operation modes produced notable differences in terms of build quality (porosity), microstructure, and properties over the sample thickness. The number and the average size of the pores were measured using a light microscope over the entire build height. A density measurement provided a quantitative index of the global porosity throughout the builds. The selective-electron-beam-melted microstructure was mainly composed of a columnar prior β-grain structure, delineated by α-phase boundaries, oriented along the build direction. A nearly equilibrium α + β mixture structure, formed from the original β-phase, arranged inside the prior β-grains as an α-colony or α-basket weave pattern, whereas the β-phase enveloped α-lamellae. The microstructure was finer with increasing distance from the build plate regardless of the selected build mode. Optical measurements of the α-plate width showed that it varied as the distance from the build plate varied. This microstructure parameter was correlated at the sample core with the mechanical properties measured by means of a macro-instrumented indentation test, thereby confirming Hall-Petch law behavior for strength at a local scale for the various process conditions. The tensile properties, while attesting to the mechanical performance of the builds over a macro scale, also validated the indentation property measurement at the core of the samples. Thus, a direct correlation between the process parameters, microstructure, porosity, and mechanical properties was established at the micro and macro scales. The macro-instrumented indentation test has emerged as a reliable, easy, quick, and yet non-destructive alternate means to the tensile test to measure tensile-like properties of selective-electron-beam-melted specimens. Furthermore, the macro-instrumented indentation test can be used effectively in additive manufacturing for a rapid setting up of the process, that is, by controlling the microscopic scale properties of the samples, or to quantitatively determine a product quality index of the final builds, by taking advantage of its intrinsic relationship with the tensile properties
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
Disentangling phonon and impurity interactions in δ-doped Si(001)
No full textWe present a study of the phonon and impurity interactions in a shallow two dimensional electron gas formed in Si(001). A highly conductive ultra-narrow n-type dopant δ-layer, which serves as a platform for quantum computation architecture, is formed and studied by angle resolved photoemission spectroscopy (ARPES) and temperature dependent nanoscale 4-point probe (4PP). The bandstructure of the δ-layer state is both measured and simulated. At 100K, good agreement is only achieved by including interactions; electron-impurity scattering (W0=56 to 61meV); and electron-phonon coupling (λ=0.14±0.04). These results are shown to be consistent with temperature dependent 4PP resistance measurements which indicate that at 100K, 8 of the measured resistance is due to impurity scattering with the remaining 1/8 coming from phonon interactions. In both resistance and bandstructure measurements, the impurity contribution exhibits a variability of for nominally identical samples. The combination of ARPES and 4PP affords a thorough insight into the relevant contributions to electrical resistance in reduced dimensionality electronic platforms. © 2014 AIP Publishing LLC
Improvements of a simple piezoresistive array armband for gesture recognition
No full textThis study presents a simple Human Machine Interface (HMI) for gesture recognition purpose, based on a wireless piezoresistive armband. The armband embeds three sensors based on Force Sensitive Resistors (FSRs) applied on specific forearm muscles, which provide signals comparable to the electromyography linear envelope. The system aims to recognize in real-time some hand gestures, opportunely processing the force signals. The HMI control system is based on Arduino platform and implements a Linear Discriminant Analysis (LDA) classifier to perform real-time gesture recognition. The HMI, by means of a Bluetooth module can wireless connect to a computer and provide commands to custom graphical interfaces or other applications as videogames. Four healthy volunteers were involved in testing the device. A double threshold segmentation technique, applied to the recorded FSR signals, allowed to detect and extract features regarding the whole-time evolution of a performed gesture, explicitly considering the transition between gestures. LDA classification performances were assessed by applying the 10-fold cross validation. The mean accuracy across all participants resulted 93.48%. The results suggest that the HMI device allows easy user’s interaction with a computer in real-time. In prospective, this device could find practical applications in neuromotor rehabilitation (e.g. exergaming), and in controlling prosthetic hands
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