1,721,028 research outputs found
Quantitative process development for biological methane production from gaseous substrates using methanogenic archaea
No full textDie vorliegende Dissertation beschäftigt sich mit der wissenschaftlichen Entwicklung eines Ein-Schritt Prozesses für die biologische Methanproduktion mit Fokus auf die Prozesstechnologie. Die potentiellen Anwendungsgebiete sind einerseits die Umwandlung von CO2- und H2-hältigen Abgasen sowie der Einsatz als "Power to Gas" Technologie. Für eine erfolgreiche industrielle Anwendung müssen jedoch einige Voraussetzungen erfüllt sein. Die wichtigsten Voraussetzungen für alle Anwendungen sind eine hohe volumetrische Produktivität, eine hohe Methankonzentration im Produktgas sowie die Langzeitstabilität des Prozesses.Im Falle der Umwandlung von Abgasen, muss überdies die Toleranz gegenüber Nebenkomponenten gegeben sein, im Falle einer "Power to Gas" Technologie, eine schnelle Reaktion gegenüber intermittenter Gasversorgung.Der Hauptfokus wurde darum auf prozesstechnologische Ansätze gelegt um einen Prozess zu entwickeln, der den oben genannten Anforderungen gerecht wird.Im Falle der volumetrischen Methanproduktionsrate (MER) und der Produktqualität, wurde zunächst erfolgreich eine Gaslimitation der Kultur nachgewiesen. Darauf folgend wurden zum ersten Mal, den Gas/Flüssig Massentransfer beinflussende Parameter systematisch auf ihren Einfluss auf die MER und die Methankonzentration im Produktgas hin untersucht. Dies erlaubte es eine Prozessstrategie zu entwickeln, die eine hohe MER bei gleichzeitig hoher Methankonzentration ermöglicht.Weiters wurde Membranbegasung der Kultur als technische Möglichkeit zur Erhöhung des Massentransfers getestet. Während die erreichten Transmembranflüsse relativ niedrig waren, konnte dennoch erfolgreich gezeigt werden, dass Mebranbegasung die Verfügbarkeit des eingetragenen Wasserstoffs für die Zellen erheblich erhöht.Im Falle der Verträglichkeit von Realgasen als Edukte für die biologische Methanproduktion, musste zuerst eine generische Methode für die Quantifizierung des Einflusses von darin enthaltenen Nebenkomponenten auf die physiologische Umwandlungskapazität der Kultur entwickelt werden.Mit Hilfe dieser Methode wurden dann drei verschiedene industrielle Gasmischungen, unter anderem Roh-Biogas, auf ihre Einsatzmöglichkeit als Edukte für die biologische Methanogenese hin getestet. Dies erlaubte es, zum ersten Mal, eine direkte Quantifizierung des Einflusses etwaiger Nebenkomponenten auf die Prozessleistung durchzuführen.Überraschenderweise zeigte keine der vorhandenen Nebenkomponenten in den vorliegenden Konzentrationen (unter anderem CO, O2 und kurzkettige Alkane) einen negativen Einfluss auf die physiologische Umwandlungskapazität der Kultur.Im Falle der intermittenten Gasversorgung, lag das Hauptaugenmerk auf der Identifizierung von, die Reaktionszeit beeinflussenden kritischen Prozessparametern. Mit Hilfe einer voll automatisierten Prozesssteuerung wurden verschiedene Parametersätze auf Ihren Einfluss auf die Reaktionszeit hin untersucht. Unter optimalen Bedingungen konnten Übergangszeiten von Stillstand auf 100% der MER im Gleichgewichtszustand von unter zwei Minuten erreicht werden.Der Prozess konnte über Zeiträume bis zu 1000 Stunden stabil gefahren werden. Sogar hoch dynamischen Zuständen, wie bei der intermittenten Gasversorgung zeigten keine negativen Auswirkungen auf die Langzeitstabilität.Zusammenfassend, kann gesagt werden, dass der verwendete Stamm, M.marburgensis, alle Anforderungen für eine industrielle Anwendung erfüllt. Die limitierenden Faktoren auf dem Weg zu einer adäquaten MER und Produktqualität konnten erfolgreich spezifiziert werden. Die Quantifizierung der Auswirkung von Realgaskomponenten auf die Prozessleistung zeigte exzellente Verträglichkeiten und die Prozessbedingungen für eine dynamische Prozessteuerung ohne negativen Einfluss auf die Prozessstabilität konnten erfolgreich ermittelt werden.All dies zeigt, dass die biologische Methanogenese als technischer Prozess, mittlerweile mehr ist als nur eine Idee. Die gezeigten Resultate bilden eine exzellente Basis für zukünftige Forschung und Prozessentwicklung genauso wie für eine erfolgreiche Maßstabsvergrößerung hin zum Pilotmaßstab.This dissertation aims on science based development of a one step process for biological methane production (BMP) using methanogenic archaea, focusing on process technological aspects. The fields of application are mainly, CO2 or H2 rich waste gas conversion and the use as "Power to Gas" technology. For an industrial application however, some process requirements have to be fulfilled. The main requirements for all applications are: high volumetric productivity and high CH4 concentrations in the product gas as well as long term stability. For waste gas conversion additionally, the stability towards side components present in those gasses has to be ensured and for a power to gas application, a highly dynamic reaction towards intermittent hydrogen supply has to be possible. The main focus was therefore put on process technological approaches to create a process capable of fulfilling the above mentioned requirements.In the case of the volumetric methane production rate (MER) and product quality, a successfull identification of gas limitation of cultures of M. marburgensis has been performed. Subsequently critical fermentation parameters influencing gas liquid mass were for the first time systematically tested towards their influence on MER and CH4 offgas concentrations. This enabled to develop a strategy towards a high MER at high product quality. Furthermore membrane gassing of the culture was tested as technical solution to improve gas/liquid mass transfer. While the overall reached transmembrane flows were quite low it could be shown for the first time that membrane gassing significantly enhanced the availability of the supplied hydrogen for the cells. In the case of the effect of waste gas side components on the physiological conversion capacity of the culture, first of all a generic method for quickly assessing the impact of real gasses as reactant gasses was developed. Applying this method, three different industrial gas mixtures, including raw biogas, were tested for their applicability as reactant gasses for BMP. This enabled us for the first time to directly quantify the influence of the present side components on the cultures performance. Surprisingly, none of the side components (e.g.CO, O2, short chain alkanes) present in any of the gasses showed an impact on the physiological conversion capacity of the culture.In the case of dynamic hydrogen supply, the main focus was put on the identification and optimisation of critical operation parameters influencing the response to intermittent gas supply. Using a fully automized process control, different parameter sets were tested towards their influence on the cultures reaction time. Under optimum conditions a recovery time of less than two minutes from stand by mode to 100% of the steady state MER was achieved. Process stability could be ensured for time periods up to 1000 hours.Even under the highly dynamic conditions created by intermittent gas supply, long term stability was given.Conclusive, it can be stated, that the used strain, M. marburgensis, fulfils all prerequisites for an industrial application. The bottlenecks towards a sufficiently high MER and a proper product quality could successfully be revealed. The quantification of the influence of waste gas components on the cultures performance showed excellent tolerance and the operation conditions for a dynamic process control without affecting process stability are known.This not only shows, that BMP is already more than just an idea but provides a good basis for further research and process development as well as for upscaling to pilot scale
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
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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