1,720,953 research outputs found
Processing Ferroalloys from Lean Ore and Fines using Thermal Plasma
No full textThe depletion of high grade ore minerals and scarcity of fossil fuel reserves are challenging factors for metallurgical industries in the future. In addition, extensive mining for increased steel demand results in the generation of fines, often found unsuitable for use as direct feedstock for the production of metals and alloys. Apart from mines waste, the other major sources of fine minerals are leftover in charge burdens, sludges, and dust generated in the high-temperature process. Sludge and fines generated during beneficiation of ore add to this woe, as the outcomes of beneficiation plants for lean ores show better yield for fine particles. These are becoming an environmental hazard, and need utilization for economic and environmental aspects. The production of ferroalloys is dominated by the Submerged Arc smelting route and also is limited to lumpy ores or agglomerates. With the evolution of DC/plasma arc smelting, direct charging of fines for ferroalloys production, particularly ferrochrome, has been made feasible in recent years. However, continuous improvements in the process economy are essential. The utilization of lean ore and wastes in ferroalloys production requires wide research and adoption of new advanced technologies for quality production with time-saving operations. Thermal plasma has several advantages over conventional pyro-metallurgical processes viz. no constraint in size and composition of the feedstock, comparatively higher recovery rates, purity in alloy grade, and so on. Thus, the present research is focused on the use of thermal arc plasma for production of ferroalloys, i.e., ferrochrome, ferromanganese, and ferrotitanium from ore mineral fines and mines waste. Friable chrome ore of Indian origin is subjected to carbothermic reduction at 1450 ℃, where the chromium and iron oxides are partially reduced and metallized with the formation of slag phases. The addition of flux and the type of reductant affects the reduction rate as confirmed from characterization studies. The subsequent milling and magnetic separation result in the elimination of gangue up to 70% by weight. The fine magnetic materials are found suitable for plasma smelting with a lime-rich melilite composition, which is advantageous over the current industrial (cordierite slag) practice. The comparative study of smelting ore with/without slag chemistry and magnetic parts of partially reduced chromite evidences that the latter route i.e. smelting after magnetic separation, is more advantageous for minimizing processing cost and improving alloy quality as well as recovery rates. The chromium and silicon content in ferrochrome alloy is about 68% and less than 0.5% by weight, with overall metallic recovery rates exceeding 95%.The generated melilite slag can also be used in cement production after granulation. Phase, composition, and thermal analyses of different manganese ore fines are investigated. The minerals associated with ores exhibit various thermal transformations and inversions, and are quantified. The ores are of medium grade, ferruginous, alumina-rich ferruginous, and siliceous types. Reducibility, phase, and microstructure evolution of stiff extruded briquettes under vacuum made from above ores are studied in the temperature range of 1000 ℃-1400 ℃. Physico-mechanical properties are evaluated for cold and reduced briquettes and observed that beyond 1300 ℃ briquettes partially melted and deformed. XRD and SEM-EDS analyses evidence the presence, formation, and distribution of liquid silicate and or aluminate complex phases, might be responsible for retarding reduction rates. Further, smelting tests/works are carried out for studying different slag chemistry. The comparative study shows that high alumina in the final slag has less impact when basicity increases beyond 1.0. Alumina rich ferruginous ores are adjusted to the MgO-Al2O3-CaO-SiO2 and CaO-SiO2-Al2O3 slag systems, and it is observed that the increase in basicity ratios improves recovery rates. Siliceous ore upon smelting results in high silicon pick-up in the alloy, and the phase and composition satisfies ferro-silicomanganese alloy grade. Ilmenite on carbothermic smelting in thermal plasma resulted in pig iron and titania-rich slag as end products. Further, to produce ferrotitanium, combined carbothermic and aluminothermic reduction approaches are made in stages and varying compositions. It is seen that lime addition into charge mixture lowered the recovery rate of titanium, by forming calcium titanate (in varying CaO/Al2O3 ratios). However, the addition of carbon and aluminium in stages has the benefit of utilization of heat lost in between steps if carried out in separate processes. Phase analysis and the microstructural investigation reveals the presence of iron-rich FeTi and Ti phases in the produced alloy. The next approach made to use carbon, aluminium, and silicon as reductants in stages. This combined stage-wise reductant injections in an uninterrupted single process form ferrotitanium silicide of varying composition, which is of high value particularly while making RH degassing of steel. The direct use of ore fines and wastes avoiding agglomeration is cost-effective over lumpy high-grade ore minerals. The beneficiation of lean ores with subsequent change in slag chemistry fit into the requirement of thermal plasma
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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