1,720,956 research outputs found
Comparison between downdip and updip groundwater flow on early CO<sub>2</sub> migration in dipping storage aquifers
No full textThe impact of the aquifer dip angle and groundwater flow have been investigated in the field of carbon dioxide (CO2) storage efficiency and security. However, no consideration has been given to the significance of the direction of groundwater flow in aquifers on the CO2 plume migration and the storage performance. In this study, we analyse the effect of the direction of groundwater flow on CO2 plume migration in the subsurface, implementing a numerical modelling approach. We compare the early plume migration in storage aquifers of various dip angles when the groundwater flows downdip with when it flows updip. We estimate the injected plume size, and the instantaneous velocity of the leading tip of the plume. When the groundwater flows downdip, against the direction of CO2 plume migration, the plume becomes more stretched, its greater extent and thus height causing it to accelerate during its updip migration due to the increase in buoyancy. By contrast, the plume decelerates over time when groundwater flows updip. This is because of a decrease in the size of the mobile CO2 plume due to enhanced residual and dissolution trapping at its trailing edge, reducing buoyancy, and hence decreasing the risk of CO2 leakage during its early migration.</p
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
A numerical analysis of background flow velocity effects on long-term post-injection migration of CO2 plumes in tilted storage aquifers
Get PDFEven though groundwater flow exists in many saline aquifers, very few studies have investigated its significance on the injected CO2 migration and trapping processes. Here, a numerical simulation approach is used to study the late post-injection migration and trapping of CO2 injected into a tilted aquifer. The analysis highlights that although the migration of the CO2 and its dissolution in brine is induced by buoyancy, the existence of background flow can further affect the plume velocity, convective dissolution, the dissolved CO2 flux and its distribution in the storage complex. Our analysis shows that the background flow removes the residual CO2, by dissolution, before the convective dissolution of the mobile part becomes dominant. The plume decelerates during its vertical migration by a factor of 6.5; then, its height increases with time to more than 15% as background flow velocity increases, hence reducing its rate of deceleration. However, when the plume reaches its maximum height, it migrates with a constant velocity. Greater background flow velocity not only allows the plume to migrate further, but it may hinder CO2 dissolution. This is because it can transport the dissolved CO2 underneath the plume for a long time, thus slowing down the interaction at the CO2-brine interface. The weak and strong background flows can impact the tendency of the dissolved CO2 to persist underneath the caprock. Our results indicate the existence of a critical background flow velocity which can control the distribution of the dissolved CO2 at the bottom of the aquifer, further away from the caprock.Document Type: Original article Cited as: Awag, M., Mackay, E., Ghanbari, S. A numerical analysis of background flow velocity effects on long-term post-injection migration of CO2 plumes in tilted storage aquifers. Advances in Geo-Energy Research, 2024, 11(2): 103-114. https://doi.org/10.46690/ager.2024.02.0
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
The impact of background water flow on the early migration of a CO2 plume in a tilted aquifer during the post-injection period
Get PDFThe study presents a numerical modelling analysis on CO2 plume migration in a dipping storage aquifer with background flux, which incorporates residual and dissolution trapping of CO2. The purpose of this analysis is to investigate the effect of the background flow velocity on the CO2 plume migration during the early post-injection period. Different velocities of groundwater flow from low to high were considered in the aquifer model. The distribution, migration distance and velocity of the injected CO2 plume as well as the remaining mobile CO2 plume extent are estimated to determine how fast and far the plume propagates with time. Comparison of the results indicate that increasing the background flux velocity causes the plume to migrate longer distances up-dip, while it reduces the height distribution of the plume with time. This reduces the volume of mobile CO2 in the storage aquifer at larger velocities of background flux, hence decreasing the leakage risk of CO2 to the surface. In addition, the CO2 plume decelerates immediately after cessation of injection as its bottom rises vertically and the buoyancy force reduces as the thickness of the plume reduces. However, the plume then accelerates during the initial period of its subsequent lateral migration, as the plume becomes extended, and the buoyancy forces increases somewhat. The degree of lateral extension increases with increasing background water flow velocity, with the leading tip of the plume migrating faster than the trailing edge, until residual and dissolution trapping sufficiently reduce the volume of free phase CO2 that its migration is arrested.Document Type: Original articleCited as: Awag, M., Mackay, E., Ghanbari, A. The impact of background water flow on the early migration of a CO2 plume in a tilted aquifer during the post-injection period. Advances in Geo-Energy Research, 2023, 9(2): 125-135. https://doi.org/10.46690/ager.2023.08.0
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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