1,720,969 research outputs found
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
Characterizing the deformation response of a unidirectional non-crimp fabric for the development of computational draping simulation models
Get PDFIn several countries around the world, including Canada, government incentives have been put in place to improve the fuel efficiency of vehicles and reduce CO2 emissions. Improvements in composites manufacturing technology, such as high-pressure resin transfer molding and quick curing resins, makes it practical to lightweight through the incorporation of carbon fiber reinforced polymer (CFRP) parts into the body-in-white structure of vehicles. However, the technology has only been realized for small production rates and is currently in the developmental phase towards full automation for high-volume production. Hence, there is a need to developed and calibrate fabric draping simulations models to support this effort and enable the design of CFRP production processes that incorporate cost-effective fabric reinforcement material, such as heavy tow unidirectional non-crimp fabric (UD-NCF). This work aimed to expand the understanding of the forming behaviour of UD-NCFs, within the context of the development of automation capabilities for fabric preforming. The investigation focused on the characterization of the macroscale response of a UD-NCF, including an investigating of associated local deformation mechanisms, to calibrate a macroscale constitutive model and support the development of a computational fabric draping simulation model.
The fabric characterization consisted of a series of experimental tests that measured the fabric in-plane and out-of-plane deformation responses reminiscent of draping operations. The tests were conducted with respect to the carbon fiber (CF) tow longitudinal and transverse directions. The experimental tests conducted were the longitudinal, transverse, and off-axis extension tests; the picture frame test (PFT); the cantilever; and friction sliding test in both material directions. The longitudinal extension and bending stiffness were found to be significantly higher than the respective transverse extension and bending stiffnesses. Also, at low strains, the fabric transverse extension stiffness was found to be negligible until crimping in the transverse glass fibers was removed. Regarding the fabric friction response, the coefficients of friction were higher on the stitching fabric side and when sliding occurred in the longitudinal fabric direction. Also, an investigation of the fabric mesoscale deformation mechanisms revealed the generation of CF tow undulations and intertow gapping, mainly generated by deformation of the stitching, when the fabric was subjected to transverse extension and shear deformations. To address difficulties associated with sliding of the glass fibers at the clamps during extension and PFT testing a clamping design was proposed that fully restrained the glass fibers, while at the same time preventing specimen damage at the grips. 2D DIC was used to study the development of strains in the fabric during all in-plane experimental tests. Challenges associated with fabric surface texturization and strain measurements through digital image correlation were investigated and addressed to improve the optical strain analysis. A surface texturization technique with an oil-based paint was implemented in all tests as it created high contrast speckle patterns on the fabric surface and the least amount of fabric deformation interference when compared with two other surface texturization techniques.
Using the experimental results, a macroscale material model, chosen from the existing material model library available in the commercial finite element software LS-DYNA® was calibrated to simulate forming operations. The material model was calibrated for in-plane and out-of-plane deformation modes in accordance with the experimental tests conducted. The material model parameters were identified by simulating the experimental tests conducted during the fabric characterization process and an iterative inverse parameter identification approach until a good correlation was obtained between the numerical simulations and the corresponding physical tests. In most cases, piecewise linear functions were used to approximate the experimental test data before entering into the material model.
Finally, to validate the calibration of the material model, a single-layer 100-mm diameter hemispherical test with a displacement controlled punch was performed and simulated using the calibrated material model. In addition to the calibrated material model, results from the friction tests were used to define contact boundary conditions in the draping simulation model. A good agreement was obtained between the simulation predictions of macroscopic deformations observed in the fabric, including contour shape and wrinkling, and the experimental results
Constitutive and Fracture Characterization and Modelling of Monolithic and Tailor-Welded Blanks of Press-Hardening Steels
Get PDFThis study investigates the constitutive (flow) and fracture response of two automotive-grade press-hardening steels, Usibor® 1500-AS and Ductibor® 500-AS, as well as their tailor-welded blanks (TWBs), for a range of as-quenched microstructures. Three different microstructures of each steel grade were developed through various quench-hardening heat treatments, comprising austenitization followed by air, die, oil, and/or water cooling. Mono- and multi-gauge laser-welded blanks of Usibor® 1500-AS and Ductibor® 500-AS, with three distinct combinations of 1.2-mm and 1.6-mm thicknesses, were also produced in the die-quenched condition.
For the as-quenched Usibor® 1500-AS and Ductibor® 500-AS monolithic blanks, characterization campaigns were conducted by means of mechanical tests, including shear, hole expansion, uniaxial tension, V-bend, and plane-strain and equibiaxial tension Nakazima domes. Both steel grades exhibited a high degree of sensitivity to cooling rate in terms of mechanical properties. For Usibor® 1500-AS, the fully-martensitic (oil-cooled) and fully-bainitic (air-cooled) microstructures had the highest strength and ductility, respectively, while the bainitic-martensitic (forced air-cooled) microstructure exhibited intermediate mechanical properties. For Ductibor® 500-AS, the mostly-martensitic (water-cooled) microstructure showed the highest strength and lowest ductility, followed by the intermediate ferritic-martensitic plus tempered martensite/bainite (die-cooled) and mostly-ferritic (air-cooled) microstructures, respectively.
The mechanical response of the as-quenched microstructures of Usibor® 1500-AS and Ductibor® 500-AS was modelled using a novel, coupled micromechanical-phenomenological strategy. In this approach, the constitutive behavior of the multi-phase steels was predicted using new mean-field homogenization (MFH) techniques, denoted the Samadian-Butcher-Worswick (SBW) formulations, with or without considering carbon-partitioning effects. The fracture response was estimated by tracking damage accumulation within each constituent phase using the phenomenological Generalized Incremental Stress-State-dependent damage MOdel (GISSMO) based on the micro-scale stress and strain states calculated by the MFH models. The proposed modelling strategy was shown to accurately predict the flow curves, fracture strains, and fracture loci of the bainitic-martensitic Usibor® 1500-AS and ferritic-martensitic Ductibor® 500-AS for the range of micro-constituent volume fractions considered.
The hot-stamped TWBs were subjected to tensile, equibiaxial tension Nakazima dome, and V-bend experiments with various weld orientations relative to the major principal stress direction. In the majority of the mechanical tests, fracture was initiated in one of the parent metals. Fracture initiation occurred in the Ductibor® 500-AS parent metal during the transverse tensile and equibiaxial tension Nakazima dome tests, whereas the Usibor® 1500-AS parent metal fractured in the longitudinal tensile and 45° and 90° V-bend tests. The only exception to the parent-metal failure was observed during the V-bend tests with the weld line lying on the punch-tip edge, for which fracture was initiated within the weld.
Finite-element models of the TWB experiments were developed within the LS-DYNA software using either the measured or predicted constitutive properties and fracture loci of the parent metals. A mapping scheme was created to assign the mechanical properties of each region of the TWBs to the corresponding elements based upon the measured local hardness. Two scenarios were examined for the TWB models: (i) including and (ii) excluding the detailed variation of mechanical properties within the weld region. The predictions revealed that the inclusion of the narrow weld region of the laser-welded blanks within the hardness-mapped TWB models resulted in an improvement of the predictions in terms of the load-displacement response and fracture locations, as compared to the “without weld” scenario.
A key outcome of this research was the quantification of the strong quench-rate sensitivity of the mechanical properties of Usibor® 1500-AS and Ductibor® 500-AS, which will affect their in-service (crash) performance after hot stamping. The developed modelling frameworks have direct application to predict the mechanical response of these steels and their TWBs subjected to hot-stamping processes in which quench rate: (i) is intentionally varied, such as within the tailored in-die heating technique; or (ii) naturally changes, for example, through fluctuations associated with the tooling temperature and contact pressure over time as well as transients during the startup and shutdown of production lines
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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