1,720,957 research outputs found
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
A preliminary investigation on the mechanical behaviour of a stiff Italian clay in the context of hydrogen storage
Full text linkThe large-scale use of renewable energy sources is closely linked to the ability to store excess energy generated
during periods of overproduction for use when demand is at a peak. Storing green energy is therefore a key
component in the move towards a carbon-neutral economy. Underground hydrogen storage in depleted oil and
gas reservoirs may provide an efficient long-term solution. Cyclic injection and production of hydrogen alter the
chemo-hydro-mechanical conditions of the reservoir and caprocks, and possible geomechanical consequences of
such alterations must be preliminarily assessed for safe storage operations. This study aims at exploring the
possible effects of cyclic mechanical loads, such as those that might be induced by hydrogen storage and production, on the mechanical behaviour of a clayey caprock. A series of triaxial tests, both monotonic and cyclic,
were carried out on undisturbed samples of a stiff Italian clay cored from a caprock formation overlying a hydrocarbon reservoir. The results show that the material response is characterized by the distinctive stress-strain
behaviour of stiff clays, with a rather high fragility, which was found to be highly dependent on the loading
strain rate. During laboratory experiments conducted at frequencies larger than in situ ones, cyclic loading under
stress control causes a gradual degradation of the material structure leading to the formation of a clear shear
band followed by a reduction in shear strength. Eventually, failure occurs as the peak shear strength approaches
the applied load. The progressive destructuration also implies a reduction in P- and S-wave propagation velocities and a significant change in the signal shape, which is therefore a promising parameter for monitoring the
material degradation process
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
Robust numerical implementation of a 3D rate-dependent model for reservoir geomechanical simulations
No full textA 3D elasto-plastic rate-dependent model for rock mechanics is formulated and implemented into a Finite Element (FE) numerical code. The model is based on the approach proposed by Vermeer and Neher (A soft soil model that accounts for creep. In: Proceedings of the International Symposium “Beyond 2000 in Computational Geotechnics,” pages 249-261, 1999). An original strain-driven algorithm with an Inexact Newton iterative scheme is used to compute the state variables for a given strain increment.The model is validated against laboratory measurements, checked on a simplified test case, and used to simulate land subsidence due to groundwater and hydrocarbon production. The numerical results prove computationally effective and robust, thus allowing for the use of the model on real complex geological settings
Advances in geomechanical subsidence modeling: Effects of elasto-visco-plastic constitutive behavior
No full textO&G companies, during normal activities of field development planning and execution, have to assess their projects in terms of environmental sustainability in addition to technical and economic feasibility. With such a primary aim, Eni's commitment to both monitoring and modeling of subsidence has been very strong since the early nineties. Most offshore development platforms have been equipped with GPS stations, able to continuously monitor horizontal and vertical displacements, and radar images are constantly acquired and interpreted for onshore fields. To complete the internal approach, a workflow based on elasto-plastic finite element modeling has been implemented in order to properly reproduce the measured data and to accurately predict the future evolution of the settlement phenomenon. In some cases, it is beneficial to enrich classical elasto-plastic constitutive models to fully reproduce the time evolution of subsidence as recorded by continuously monitoring instruments such as GPSs. Actually, the extension of those models with the introduction of a viscosity component allows for a more detailed match of the recordings, with an increased reliability of the forecasted evolution scenarios. In this paper, the elasto-visco-plastic law by Vermeer and Neher (VNM) is evaluated as a possible constitutive model for the simulation of subsidence occurring above gas and oil reservoirs. This elasto-visco-plastic model can be regarded as a natural extension of the modified Cam-Clay model (MCCM), usually employed by Eni for subsidence modeling. Furthermore, its parameters have a clear physical meaning and can be easily determined from laboratory tests. Oedometer and creep tests performed on sand samples from gas reservoirs are first introduced together with model predictions. Then, a synthetic, nevertheless realistic, case study is analyzed to assess the capabilities of this elasto-visco-plastic model in the simulation of subsidence. Elasto-plastic (MCCM) and elasto-visco-plastic (VNM) simulations are compared to outline the implications of the elasto-visco-plastic modelling in the simulation of subsidence evolution. The results presented herein show that the VNM can adequately reproduce time dependent effects observed in laboratory testing of reservoir materials and, in some cases, can potentially improve the match of complex subsidence histories provided by elastoplastic models
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