1,720,993 research outputs found
Transient transport of polymer solution flow in porous media
Full text linkKazakhstan takes 12th place in World oil production, however 52,7 % of produced oil comes from “mature” fields that are on the last production stages. Therefore, use of enhanced oil recovery methods becomes essential; one of these methods is polymer flooding, which involves injecting a polymer solution into the reservoir in order to displace trapped oil towards the wellbore. For successful injection of polymer solutions in a reservoir it is essential to study properly their behavior in porous media. This master thesis focuses on that topic, by describing and understanding two main factors that have a great impact on polymer transport, namely (i) the inaccessible pore volume (IPV) and (ii) polymer retention due to its adsorption on grain surfaces within the porous medium. In order to reach this goal experiments on core samples (plugs) were conducted, and effluent concentration profiles were obtained. Moreover, numerical modelling was implemented to characterize diffusion/adsorption of polymer molecules inside the porous core
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
Dynamic modelling of an immobilized enzyme bioreactor
No full textBibliography: p. 81-84.Dynamic experiments provide an excellent means for the determination of crucial process parameters, such as the axial Peclet number, the intraparticle and external mass transfer coefficient and the intraparticle reaction rate constant, in fixed or liquid fluidized bed immobilized enzyme bioreactors. The absence of a complete and comprehensive solution of the model equations in the real time domain, as well as significant advances in the area of statistical moments analysis has rendered the latter approach the dominant one for parameter estimation in fluid-solid reacting systems. Nevertheless, an efficient and easily implementable solution of the model equations in the real time domain, as opposed to the solution in the Laplace domain needed for the statistical moments analysis, opens new possibilities in the design of fixed or fluidized bed bioreactors since, apart from parameter estimation via dynamic experiments, it is suitable for simulation, optimization and control. This paper presents a dynamic model for a fixed or liquid fluid bed immobilized enzyme bioreactor, along with a novel method for the solution of the coupled partial differential equations in the real time domain. Both, the tanks-inseries and the dispersion models have been used to describe the non ideal axial mixing in the reactor. The solution, in its final form, comes in both cases as a system of simultaneous ordinary differential equations; this is readily implementable on a computer and can be easily solved by commercially available software packages. Based on this solution, a complete parametric analysis was performed. That analysis revealed the importance of intraparticle and external mass transfer resistances, intraparticle chemical reactio?? and axial dispersion on the transient behaviour of the reactor. Most important, that analysis revealed ways for parameter estimation and system identification via simple dynamic experiments. The design and optimization implications of the study are finally demonstrated by using the derived solution to simulate the performance of an immobilized urease bioreactor with a recycle loop. Such a configuration is characterized by time varying feed concentration and can be used, as part of an extracorporeal artificial kidney device, for the treatment of uremic patients
A Study of Cell Signalling in the Human Fallopian Tube
No full textEThOS - Electronic Theses Online ServiceGBUnited Kingdo
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