1,720,953 research outputs found
Effects of the Deposition of Various Fines during Hydrotreating of a Bitumen Derived Gas Oil
Get PDFThe processing and upgrading of the Canadian Athabasca Oil Sands is necessary to meet the demands of a growing global economy in a world of diminishing reserves. As such, the reduction in operating costs is imperative to further increase the amount of economically feasible reserves. Hydrotreating is a secondary upgrading method which, at elevated temperatures and pressures in the presence of hydrogen and a catalyst, removes contaminants from the oil stream. This both improves the quality of the produced oil by increasing the H/C ratio and allows the contaminants to be processed at the upgrading facility rather than be vented as exhaust.
The purpose of this research was to compare the different types of fine particles that enter an industrial hydrotreating unit within a controlled setting. By comparing the catalyst activity and pressure buildup between mineral fines (namely kaolinite, montmorillonite, and pyrite), produced solids (petroleum coke), and corrosion products (iron (III) oxide), it was hoped that any discovered differences could be exploited through optimization of reactor conditions to lessen the quantity and/or impact of their fouling. This was performed using a laboratory-scale continuous-flow packed bed reactor, which is similar to the equipment used industrially.
By comparing the pressure profiles during accelerated fines deposition of the different types of fines, it was found that mineral fines would create the earliest pressure buildup, taking 7-10 days and having a maximum pressure growth of 2885 kPa. The expected mechanism for these fines is that the surrounding asphaltene layers would desorb under hydrotreating conditions, leaving behind the minerals that were not oil-wetting, and couldn’t be carried by the passing oil stream. As more of these minerals were left behind, flow channels were blocked, and a filter cake formed at the inlet of the reactor. The second category of fines to result in pressure buildup was petroleum coke, reaching a 1193 kPa pressure drop. The mechanism driving this is that, as the petroleum coke solids break apart, any heavy metals that were contained within are left behind on the packing. This leads to the formation of a filter cake overtop of the catalyst bed. The category that took the longest for pressure to appear was corrosion products, where it was found that Fe_2 O_3 was converting to FeS under hydrotreating conditions. This formed FeS was then fouling the reactor system. This took over 40 days to be observed, with a final reactor differential pressure of 336 kPa.
In analyzing the conversion of nitrogen and sulphur within the oil stream for each experiment, it was found that catalyst deactivation due to fouling was minimal, with the main impact to hydrotreater performance being due to the pressure buildup. The one exception to this was for the iron (III) oxide experiment, where the formed FeS improved catalyst activity. However, a significant amount of iron deposition was required to achieve the same benefits as the cobalt or nickel promotors that are typically impregnated onto the catalysts during preparation.
Finally, through analysis of the textural and surface properties of the catalysts before and after the fouling had occurred, it was determined that fouling only occurred along the outer surface of the catalysts, and none of the active sites within the pores were reached. This is primarily due to the relative size between the foulants and the catalyst pores. Catalyst specific surface area was between 140-148 m2/g for all samples.
Future research into this area should focus on optimizing reactor conditions to increase the period until pressure buildup occurs, as this is the first issue that a hydrotreater will experience due to the fouling of fine particles. Additionally, any research into possible methods for the removal of the asphaltene layer and filtration of the mineral fines prior to entering the hydrotreater could be considered as another avenue by which the reactor life cycle can be extended
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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