1,720,988 research outputs found
Towards waveform seismic filtering of mantle convection models
Get PDFEarth science has been heavily data-driven due to the abundance in data. Yet, when there are relatively a small number of hypotheses to verify, the inverse problem becomes a classification problem. It is then worth directly examining observed seismic data against predicted data. Concretely, we chain forward modelling from geodynamics to seismology. We call this process ‘waveform Seismic Low Filtering of Earth’s models’ (SeLFiE). We take seismic signals of the snapshots of forwardly generated Earth models with that of the actual Earth, as if we took a photo of ourselves. Although there have several studies on how the seismological tomographic technique can perceive the geodynamical models, there are few studies on the seismic waveform sensitivity to geodynamical or petrological parameters. A pilot test of our SeLFiE methodology was encouraging, since we used only one seismic station to constrain the melt transportation manner beneath the Réunion island (Franken et al. 2020). Here in this contribution we present our strategy and developed tools towards the waveform filtering that have been developed during and after the CLEEDI week in August, 2020
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
Imagerie time-lapse de la déformation d'une roche à l'aide de l'inversion des formes d'ondes
No full textLa supervision microscopique et macroscopique de l'évolution de la rupture est un élément clé pour nous aider à comprendre l'état des contraintes et les caractéristiques sismiques. À l'échelle microscopique, la mesure des propriétés des roches sous déformation en laboratoire nous fournit une vue globale des caractéristiques dynamiques et statistiques d'une roche. À l'aide ainsi de l'observation macroscopique, les expériences de déformation des roches à l'échelle du laboratoire nous ont apporté les connaissances essentielles pour comprendre la physique de la nucléation des séismes. La compréhension de l'évolution des fissures est également importante dans l'industrie pour surveiller le stockage des hydrocarbures et du CO2, puisque leur injection souterraine dans les réservoirs déclenche des ruptures de failles sismiques. Par conséquent, l'imagerie des scénarios de stockage time-lapse, l'étude de la sensibilité de la réponse sismique et l'investigation du processus de rupture devienneront indispensables dans l'industrie et la physique des séismes. Cette thèse propose une méthodologie d'imagerie sismique de l'état de l'art utilisant l'équation des ondes pour caractériser les changements structurels pendant la déformation de la roche. Nous avons donc développé une stratégie d'imagerie 0D et 3D time-lapse (4D) des données des expériences sismiques-actives à l'échelle du laboratoire, en proposant une méthode d'inversion pour imager efficacement les changements structurels élastiques/anélastiques pendant la déformation. Nous combinons d'abord les données observées pendant des expériences statiques et le données synthétiques pour calibrer les signaux enregistrés. Puis, nous déterminons les propriétés des ondes qui se propagent dans les échantillons. Ensuite, nous obtenons des informations sur l'hétérogénéité et l'anisotropie 3D des roches en comparant les formes d'onde observées et les synthétiques. Enfin, les méthodes d'inversion de formes d'onde et d'imagerie de migration pour les sources actives sont mises en œuvre sur les données réelles afin de reconstruire les changements de la structure localisée. La méthode d'inversion que nous proposons a un potentiel plus élevé que les méthodes classiques de laboratoire qui utilisent uniquement les temps d'arrivée.Microscopic and macroscopic monitoring of crack evolution is a key to helping us understand the stress statement and seismic features of the failures. Microscopically, the measurement of rock properties under deformation in the laboratory provides us with a comprehensive view of a rock's dynamic and statistical characteristics. Together with macroscopic observation, laboratory-scale experiments of rock deformation have brought us the essential knowledge to understand the physics of earthquake nucleation. Understanding crack evolution is also critical in the industry for monitoring hydrocarbon and CO2 storage since their underground fluid injection in the reservoirs is known to trigger seismic fault ruptures. Therefore, imaging the time-lapse storage scenarios, studying the sensitivity of the varying seismic response and investigating the rupture process is becoming indispensable and extremely important in industry and earthquake physics. This thesis proposes a state-of-the-art time-lapse wave-equation-based seismic imaging methodology to infer structural changes during rock deformation. We thus developed 0D time-lapse and 3D time-lapse (4D) active-source seismic imaging on rock samples in the laboratory, proposing an inversion method to efficiently image the elastic/anelastic structural changes during the deformation. We first combine laboratory data of static experiments and numerical modelling to calibrate the recorded signals and determine the properties of waves propagating in the samples. Second, we obtain 3D heterogeneity and anisotropy information on rocks by comparing the observed and synthetic waveforms. Finally, waveform inversion and migration imaging methods for active sources are implemented on waveforms recorded in rock deformation experiments to reconstruct localised structural changes. Our proposed inversion method has a higher potential than the classic laboratory methods using only travel times
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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