1,721,147 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
Dynamic Pore Network Study of Immiscible Two-Phase Flow in Porous Media
Full text linkPorous media research has widespread applications in a variety of fields including biology, medicine, and geology. Notably, it can be used to mitigate the effects of climate change through methods of carbon capture and storage. Fundamental to all disciplines of porous media research is understanding how fluids move through pores under different conditions. In many cases, it involves the movement of multiple fluids rather than a single fluid. An example is the displacement of brine in aquifers with carbon dioxide during carbon sequestration processes. When fluids are immiscible, that is when they do not form a homogeneous mixture, various phenomena arise that can influence the flow. For example, the interfaces between the fluids create capillary pressure barriers that depend on the interfacial tensions, the radii of the pores, and the wetting angles. Due to these barriers, different amount of force is needed to push through different pores. A porous medium can have varying radii and wettability and hence varying capillary pressure barriers along its body. As a result, when being subjected to an externally applied pressure, depending on the magnitude of the pressure, certain regions of the porous medium might become active while others remain dormant. This effect can cause the volumetric flow rate as a function of the applied pressure to deviate from the linear Darcy’s law in certain pressure regimes.
There are various ways to model immiscible fluid flow in porous media. The models can range from a simple capillary tube to a bundle of capillary tubes to a network of interconnected tubes. One way to model a dynamic pore network is through tracking and moving the interfaces. The procedure at every time step involves calculating the pressure field and thereafter the flow rates and moving the interfaces accordingly while abiding by a set of rules that makes that system more realistic.
The work in this thesis aims to contribute to a better understanding of immiscible two-phase flow in rigid porous media. The main body of work consists of 4 research papers that mostly use a numerical dynamic pore network model, and also capillary tube models. A focus was placed on steady-state non-linear dynamics in terms of the volumetric flow rate as a function of the global pressure difference. Other topics considered in this work include local statistics of porous media, critical phenomena in porous media, and the effects of compressibility
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
Local versus Equal Load Sharing in the Fiber Bundle Model
Full text linkFracture is a huge field of research that includes physics, geology, materials science, and engineering. Most approaches are very specialized, but what if we instead want to focus on the big picture to look for general behavior and effects?
The fiber bundle model is a highly simplified model that can still describe many characteristic features of fracture phenomena, and is therefore very useful when investigating fracture processes generally. This thesis studies the equal load sharing (ELS) and local load sharing (LLS) variants of the fiber bundle model.
The holy grail of fracture research is to predict when catastrophic failure will occur. The first two articles develop two different approaches that can potentially be used to predict failure: energy considerations and the distribution of smaller fracture events.
The last two articles describe effects that occur in the LLS model, but are absent in the ELS model. The first is a statistical effect that can cause an apparent stability, where the model looks stable in a region where it is unstable. The second is a shielding effect that protects weak fibers at the expense of stronger ones. This effect can, surprisingly, make the LLS model – which contains local stress enhancement at the edges of cracks – more stable than the ELS model
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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