1,720,953 research outputs found
Investigation and optimization of sewage sludge combustion in stationary fluidized bed systems
No full textDie Regelung des Verbrennungsprozesses von Klärschlammfeuerungsanlagen ist bisher aufgrund der Komplexität des Brennstoffes sehr wenig untersucht worden. Die bisherigen Erfahrungen und Untersuchungen haben gezeigt, dass in der Praxis die meisten thermischen Abfallbehandlungsanlagen immer noch nahezu ausschließlich mit den konventionellen PI- und PID-Regelungen ausgestattet sind. Aufgrund der Inhomogenität und der kurzfristigen Heizwertschwankungen der eingesetzten Brennstoffe können die geforderten Regelungsergebnisse des Verbrennungsprozesses mit den konventionellen Regelungen nicht erreicht werden.
Im Rahmen dieser Arbeit wurde die Realisierung eines stabilen automatischen Betriebs der Klärschlammfeuerung in der stationärenWirbelschichtverbrennungsanlage untersucht. Dadurch wird ein wichtiger Beitrag zu einer besseren Feuerungsregelung geleistet. Eine gleichmäßige und stabile Fluidisierung des Bettmaterials ist entscheidend für eine homogene Temperaturverteilung und eine effiziente Verbrennung. Um dies zu erreichen und somit eine optimale Betriebsbedingung der Feuerung zu realisieren, wurden im ersten Teil dieser Arbeit zwei komplexe dreidimensionale numerische Modelle der stationären Wirbelschichtfeuerungsanlagen mit dem kommerziellen CFD-Softwarepaket Fluent 14.5 entwickelt. Begleitend zu den numerischen Untersuchungen wurden ebenfalls experimentelle Untersuchungen an der stationären Wirbelschichtfeuerungsanlage durchgeführt. Die aus den numerischen Strömungssimulationen gewonnenen Ergebnisse der minimalen Fluidisierungsgeschwindigkeit und den damit eingehenden Druckabfall wurden mit den experimentellen Messungen verglichen und validiert.
Der zweite Teil dieser Arbeit befasst sich mit der mathematischen Modellbildung und dem Reglerentwurf der Klärschlammverbrennungsanlage Salierweg. Die Implementierung wurde in Matlab (Version 2014b) vorgenommen. Zu Beginn wurde ein theoretisches Mehrgrößenmodell der Wirbelschichtfeuerungsanlage aus den gemessenen Ein- und Ausgangsdaten entwickelt. Nach der Modellbildung wurde die Genauigkeit der Regelstrecken anhand einer Validierung mit den Prozessdaten überprüft. Anschließend wurden auf Basis der entwickelten Mehrgrößenregelstrecken die Regelungskonzepte für den Feuerungsprozess entworfen und getestet.
Für die Optimierung der Regelgüte wurden ebenfalls die Entkopplungen der beeinflussenden Regelgrößen voneinander berücksichtigt. Um alle möglichen Betriebszustände der Anlage zu definieren und die geforderten Rahmenbedingungen für die verschiedenen Prozessgrößen einzuhalten, wurden die Regelergebnisse mit einem dezentralen PI-Regler und einem adaptiven Fuzzy-PI-Regler mit Hilfe von Matlab-Simulationen untersucht und verglichen.
Wesentliches Ziel der vorliegenden Arbeit ist die Entwicklung einer Klärschlammverbrennungsregelung, die sich kontinuierlich an sich ändernde Brennstoffeigenschaften anpasst, so dass die Anlagenstabilität und die optimale Verbrennung auch bei wechselnden Betriebsbedingungen gewährleistet ist.The control of the combustion process of sewage sludge incineration plants has been very little investigated, because of the complexity of the sewage sludge material. Previous experiences and researches have shown that in the praxis most of the thermal waste treatment plants are still almost exclusively equipped with PI and PID controllers. Due to the inhomogeneity and the short-term fluctuations in the calorific value of the incinerated fuels, the required control performance cannot be achieved by using conventional control methods. Within the framework of this Work, the realization of an automatic stable operation of sewage sludge combustion in the stationary fluidized bed incinerator was investigated. Thus can make an important contribution to achieve better combustion control. A uniform and stable fluidization of the bed material are crucial for a homogeneous temperature distribution and an efficient combustion. In order to achieve this and thus to realize an optimal plant operating condition, two complex three-dimensional numerical models of the fluidized bed combustors were developed in the first part of this dissertation by using the commercial CFD software package Fluent 14.5. In addition to the numerical investigations, comparative experimental investigations were also carried out on the bubbling fluidized bed combustor. The results of the minimum fluidization velocity and the resulting pressure drop obtained from the numerical flow simulations were compared and validated with the experimental measurements.
The second part of this thesis deals with the mathematical modelling and controller design for the stationary fluidized bed incinerator Salierweg Bonn. The implementation was done in Matlab (version 2014b). At the beginning, an experimental multivariable system of the bubbling fluidized bed incinerator was developed from measured input and output variables of the unit. After developing the multivariable mathematical model, the accuracy of the control systems was checked and validated by using collected operational data. After the validation, the combustion control methods were designed and tested based on these developed multivariable control systems. To optimize the control quality, the decoupling controllers, which eliminate the interaction between the controlled variables, were also considered. In order to define all possible operating states of the bubbling fluidized bed incinerator and to meet all required conditions for various process variables, the control results of the decentralized PI and an adaptive fuzzy PI controller were evaluated and compared using Matlab simulations.
The main objective of the present work is the development of continuous and adaptive combustion control to the constantly changing properties of the sewage sludge fuel in order to optimize the combustion process, so that the system stability and optimum combustion for all changing operating conditions is assured
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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