1,720,955 research outputs found
Process-based modelling of turbidity-current hydrodynamics and sedimentation
No full textThe production potential of deep-water reservoirs is primarily determined by rock bulk volume, porosity and permeability. Quantification of the geometry and spatial distribution of reservoir sands in deep-water deposits can provide crucial information to assess sand body volume, connectivity and the distribution of permeability baffles. This study aims to investigate the influence of turbidity-current process, sediment composition and basin-floor relief, on the geometry and spatial distribution of reservoir sands in turbidite fans. For this purpose, a process-based model has been developed which simulates turbidity-current flow, erosion, and deposition based on principles of fluid dynamics that can deal with arbitrary basin-floor topography and accommodates various grain sizes. It employs the depth-averaged shallow-water approximation in combination with the Boussinesq approximation for density-driven flow in three dimensions. Sediment transport is modelled by an advection-diffusion type equation, and exchange with the bed is largely based on existing empirical models for sediment entrainment and deposition. The model is solved numerically on a rectangular grid representing topography by means of a second-order finite-difference approximation, and employs a shock-capturing technique to accurately model the discontinuous flow front characteristic of density-driven flows. Results are presented of laboratory-scale model validation tests, in which modelling results are quantitatively and qualitatively compared to experimental data. Laboratory experiments involve small-scale flows interacting with complex topographic features as well as multiple successive flows over the same erodible bed. Results indicate that the model is capable of simulating turbidity-current hydrodynamics and sedimentation with an acceptable degree of accuracy under a wide range of conditions.Civil Engineering and Geoscience
Salt Reserve Estimate for the Twenthe-Rijn concession
No full textAkzoNobel has been producing salt from solution-mined brine since 1919. Production in the Hengelo area started in 1933, and is still ongoing today. Because at some point in time the mineable salt will all be mined and preparations for extension of the concession will need to be made, it is important to know the remaining amount of salt in the Hengelo area. To date no singular method for estimation of these reserves has been adopted. This leaves room for the development of a local method. It was chosen to develop this method in accordance with international standards. Due to its worldwide influence and being recognised by the Amsterdam Stock Exchange that AkzoNobel is registered on, it was opted to use the code of the Joint Ore Reserves Committee (JORC) of the Australasian Institute of Mining and Metallurgy (AusIMM). The geology of the Hengelo area was modelled using a modified version of the ordinary Kriging algorithm to take into account the presence of faults. Kriging was used because it also provides an estimate of uncertainty in the horizons that are modelled. To factor in the uncertainty about the continuity of the salt body, the resources in three areas were calculated: the area was investigated as a whole, and two sub-areas were investigated separately: · Sub-area 1 is the area within 500m distance of any measurement in the area. · Sub-area 2 is the area for which the geology was previously studied in great detail by GeoWulf Laboratories[5]. This area is essentially the area in-between the different measurements. The modelled horizons and their uncertainty values were then used in a Monte Carlo simulation, yielding cumulative probability distributions for the estimated amount of salt in the three scenarios. The total amount of salt was also calculated deterministically, meaning all calculations were performed using expected values. This produced the same values as the expectations of the probabilistic approach. It was decided that the probabilistic approach of the total area produced an over-optimistic value of the total Resource, and to only use the expected values of the three areas to distinguish between Inferred, Indicated and Measured Resources. Reserves were estimated for three scenarios: 1. Salt has been produced in the past in this area using a no longer used leaching strategy that results in large caverns with multiple wells. What would be the Salt Produced if the same locations had been chosen to produce salt using the modern Single Completion Cavern design? And what would be the historical recovery? 2. Assuming no production had taken place in the past, what would be the total Salt Reserve if the field would be developed now? 3. What is the Salt Reserve left in the area? It was found that the recovery percentages per cavern as asked for in scenario 1 were so widespread that no conclusive numbers could be given. The cavern lay-out throughout the area in scenarios 2 and 3 was not optimized, but because the overall estimation process was conservative the numbers could still be used as minimal values in future evaluations of the area. The results of scenario 3 are given in the table below.Applied GeologyGeoscience & EngineeringCivil Engineering and Geoscience
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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