1,720,962 research outputs found
Quantitative identification of laser cutting quality relying on visual information
No full textIn the industrial practice of the laser cutting, the cut quality is defined in a qualitative manner by skilled technicians.
Specific features lying on the cut edges in fact compose the overall quality, i.e. inclination of striations, presence of burr
and different process zones along the edge. These attributes are evaluated by experts which at the end assess the cut
quality on the base of their personal judgment. On the other hand, measurements of roughness and burr height in
accordance to standards or internal procedures are also carried out. However, measuring is time consuming and more
important is not always in agreement with the qualitative evaluation given by skilled technicians. In this scenario, the
paper presents a method relying on visual information able to measure quantitatively a new class of quality attributes,
which opportunely combined provide an index of performance consistent to the qualitative one based on experience.
In this study, images of the cut edge of 5mm thick stainless steel AISI 304 cut with nitrogen as assisting gas are analyzed.
The image analysis algorithm utilizes both standard gradient techniques, wavelets decomposition and analyses in the
frequency domain for measuring periodic and not periodic quantities. Burr profile is isolated, the typical process zones
are successfully identified and striation’s angle is computed for each zone. The gray analysis method combining multiple
outputs from the image analysis algorithm is applied in order to compute the overall quality. The weights are set to
express correctly the judgement of technicians. The method proved reliable, relatively fast and promising for further
extension to different thicknesses and materials
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
Real-time velocity regulation for productivity optimization in laser cutting
Get PDFLaser cutting is an advanced industrial process, which has become the leading manufacturing technology for metal sheet processing, as it offers high flexibility and good productivity levels compared with other competing technologies. When the metal cutting process is performed in open-loop, though, to ensure that the desired quality levels are met, the cut is generally not performed at the maximum possible cutting speed and consequently its throughput is not the highest. To optimize productivity, two steps must be undertaken: first of all a reliable estimate of current cutting quality must be available online and, secondly, a closed-loop controller should regulate the cutting speed so that the desired quality is achieved. This work presents the design and the experimental validation of the full estimation and control architecture needed to regulate the cutting quality in terms of dross attachment, which is the main defect in this type of manufacturing process
Complementary use of pulsed and continuous wave emission modes to stabilize melt pool geometry in laser powder bed fusion
Get PDFThe most common defects in laser powder bed fusion (LPBF) namely porosity, geometrical errors, roughness and thermal deformations are principally linked with the energy input to the process. In common practice, a single set of process parameters is used to produce a whole component independently from the dimensions of the actual scan path within a given layer. However, melt pool stability is highly dependent on the scanned geometry. A possible strategy to maintain a constant melt pool is the mixed use of pulsed wave (PW) and continuous wave (CW) emission regimes. Accordingly, this work investigates the complementary use of continuous and modulated emission at fixed energy density on large and thin sections respectively. The proposed approach is tested on AISI 316L stainless steel and melt pool observations are conducted employing a coaxial monitoring system built for purpose. Temporally resolved measurements of intensity and geometrical properties of the melt pool were extracted as well as a three-dimensional spatial mapping of the molten pool area. The results demonstrate that moving from CW to a PW regime at the transition zones to thinner sections is effective in maintaining a constant melt pool size thus avoiding heat build-up and part extrusion from the powder bed
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
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