1,720,953 research outputs found
Uptake and reversibility of aluminium in calcium silicate hydrates
No full textProduktion af Portland Cement (PC) er ansvarligt for en stor del af den menneskeskabte udledning af CO2, derfor er muligheder for at sænke udledningen, eftersøgt i stor stil. En af måderne udledning kan reduceres på, er at substituere dele af cementklinkeren med såkaldte "supplementary cementitious materials" (SCM). SCM indeholder generelt mere silica og aluminiumoxid, og mindre calcium end regulært PC. Dette studie forsøger at fastlægge, hvordan kinetikken og reversibiliteten af aluminium i calcium silikat hydrat (C-S-H) ændres, baseret på dennes sammensætning. Specifikt, så undersøger den hvordan Ca/Si molar forholdet af C-S-H ændrer kinetikken af aluminium optag og egenskaberne af det resulterende materiale, og om aluminium optaget er reversibelt. For at undersøge kinetikken af aluminium optag, skulle 240 prøver af forskellige Ca/Si og Al/Si molar forhold, med varierende hydrationstider, syntetiseres og analyseres. Resultaterne viste langsommere optag af aluminium i lav Ca/Si prøver, i forhold til høj Ca/Si, hvilket indikerer at den delvise substituering af PC klinker med SCM vil retardere optaget af aluminium i C-S-H’et af cement. Derudover øger inkluderingen af aluminium den gennemsnitlige kædelængde (MCL) af C-S-H’et ved at binde brobyggende tetraedre i C-S-H. I Ca/Si ≤ 1.0 og Al/Si ≤ 0.05, bliver alt aluminium optaget i C-S-H. Reversibiliteten af aluminium i C-S-H’et blev testet, ved at syntetisere prøver af calcium aluminium silikat hydrat (C-A-S-H) som blev filtreret og tilføjet til en opløsning uden aluminium. Resultaterne viser at aluminium er reversibelt i lav Ca/Si C-S-H, med en øgende stabilitet af Al for højere Ca/Si C-S-H. Disse resultater antyder at PC, som er delvist substitueret af SCM, vil have højere niveauer af MCL, på grund af inkluderingen af mere aluminium. Da PC systemer er komplekse, betyder det ikke nødvendigvis at aluminium vil være reversible i PC systemer, selvom det måske er muligt i lav Ca/Si C-S-H.Production of Portland cement (PC) is responsible for a significant amount ofanthropogenic CO2 emissions, and ways to lower emissions are highly sought after.One way of reducing emissions is by substituting part of the cement clinker withsupplementary cementitious materials (SCMs). SCMs typically contain more silicaand alumina and less calcium than ordinary PC, which could change the compositonof hydrated cement and C-S-H. This study aims to determine how the kinetics andreversibility of aluminium uptake in calcium silicate hydrates (C-S-H) changes, basedon its composition. Specifically, it investigates how the Ca/Si molar ratio of C-S-Hchanges the kinetics of aluminium uptake and properties of the resulting solids, aswell as whether the aluminium uptake is reversible.In order to investigate the kinetics of aluminium uptake, 240 samples of varyingCa/Si and Al/Si molar ratio with varying hydration time were synthesised andanalysed. The results showed slower uptake of aluminium in low Ca/Si samples,compared to high Ca/Si. Additionally, the inclusion of aluminium increases themean chain length (MCL) of the C-S-H by binding to bridging tetrahedra in C-S-H.In target Ca/Si ≤ 1.0 and Al/Si ≤ 0.05, all the Al goes to C-S-H.Furthermore, the reversibility of the aluminium uptake in C-S-H was tested bysynthesising samples of calcium aluminium silicate hydrate (C-A-S-H) that werefiltered and added to a solution without aluminium. The results showed thataluminium is reversible in low Ca/Si C-S-H short-term, with an increasing stabilityof Al in C-S-H with higher Ca/Si.These results suggest that PC which is partially substituted by SCMs will haveincreased MCL due to the incorporation of more aluminium. As PC systems arecomplex, the reversibility of aluminium uptake in C-S-H does not necessarily meanthat aluminium will be equally reversible in PC systems
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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