1,720,953 research outputs found
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
Thermo reversible crosslinked polymers for fiber reinforced composites
No full textDas Ziel dieser Arbeit war es die positiven Eigenschaften von Thermoplasten (schnelle und einfache thermische Verarbeitbarkeit) und Duroplasten (gute mechanische und thermische Eigenschaften) in einem einzigen Material zusammenzuführen und somit eine effizientere Herstellung und Anwendung von Faserverbundwerkstoffe zu ermöglichen. Dieses Ziel wurde durch die Entwicklung eines mittels Diels-Alder-Reaktion vernetzenden Polyacrylatsystems erreicht. Auf Basis von umfangreichen ab-initio Rechnungen für verschiedene Modellsysteme, wurden für diese Arbeit das Furfuryl-Methacrylat (FuMA) und das Meta-Xylylen-Bis-Maleinimid (MXBI) für die Diels-Alders-Vernetzungsreaktion ausgewählt.
Es konnte gezeigt werden, dass die wichtigsten thermischen Kenngrößen den im Vorfeld definierten Anforderungen entsprechen (s. Kapitel 4.6). Anhand der DSC-Analysen und der rheologischen Untersuchungen konnte neben der Ermittlung der für die Anwendung erforderlichen Glasübergangstemperatur auch die Reversibilität der Vernetzungsreaktion nachgewiesen werden. Die inverse Geltemperatur, ab der sich das Material wie eine thermoplastische Schmelze verhält, liegt je nach vorhandener Dien-Funktionalität des Polymethylmethacrylat-(PMMA)-Copolymers zwischen 130 °C und 185 °C (s. Kapitel 4.5.2.1).
Durch eine Additivierung mit Schlagzähmodifiern und eine gezielte Anpassung der Molekulargewichte und Diels-Alder-Funktionalitäten im Polymer konnten die mechanischen Eigenschaften auf das Niveau von kommerziell erhältlichen PMMA-Spritzgußformmassen werden (Kapitel 4.3ff.). Das mechanische Verhalten wurde so angepasst, dass die maximale Festigkeit des Materials im Bereich des Faserversagens vorliegt, um einen optimalen Synergieeffekt im Faserverbundwerkstoff zu erzeugen. So konnten mechanische Eigenschaften des faserverstärkten Materials erzeugt werden, die deutlich über denen von anderen kommerziellen Faserverbundwerkstoffe mit reversibel verknüpfter oder thermoplastischer Matrix liegen (s. Kapitel 4.6).
Der Wirkungsgrad der thermisch reversiblen Vernetzungsreaktion bei unterschiedlichen Bedingungen konnte über Dichtemessungen und über einen Vergleich zwischen theoretischer und gemessener inverser Gelpunkt-Temperatur bestimmt werden (s. Kapitel 4.5.1 / 4.5.2.1).
Als besonders vorteilhaft erwies sich, dass die mechanischen Eigenschaften bis zur Glasübergangstemperatur im Gegensatz zu Thermoplasten durch die reversible Vernetzung denen von irreversibel vernetzen Matrixsystemen entsprachen (s. Kapitel 4.4).
Nachdem die Matrixentwicklung mit guten Eigenschaften abgeschlossen werden konnte, wurde ein effizienter Prozess zur Herstellung von thermisch reversiblen faserverstärkten Kunststoffen entwickelt (s. Kapitel 5.2.2 / 5.4). Die Imprägnierung erfolgte auf einer in der Industrie üblichen Beschichtungs-Anlage über wässrige Polymer-Dispersionen. Aufgrund der geringen Viskosität der Dispersion konnte eine sehr gute Imprägnierqualität erzielt werden. Die hergestellten Prepregs sind bereits vernetzt und im Gegensatz zu z.B. Epoxy-Amin-Prepregs bei Raumtemperatur langfristig lagerstabil (s. Kapitel 5.1).
Aufgrund des geringeren Molekulargewichts zeigte der entwickelte Werkstoff bei der Verarbeitung eine deutlich geringere Viskosität in der Schmelze (s. Kapitel 4.2.1.2). Vor allem in Bezug auf die Herstellung von Faserverbundwerkstoffen aus Prepregs, führt die geringe Viskosität zu einer besseren Verbindung der Prepreg-Lagen und somit zu einer höheren Bauteilqualität mit besseren Eigenschaften (s. Kapitel 5.2.1.4 / 5.2.2).
Bei Versuchen auf der Doppel-Diaphragma-Anlage des IKV Aachen und bei der Herstellung bei einem Automobilzulieferanten (Plastic Omnium) konnten komplexere Bauteile ausgehend vom Prepreg in Zykluszeiten von kleiner 60 Sekunden hergestellt werden. Der Prozess verläuft schneller als bei duroplastischen Systemen und ist vergleichbar mit den Zykluszeiten bei der Herstellung von thermoplastischen Faserverbundwerkstoffen, wobei ein kompletter Prozessschritt eingespart werden kann (s. Kapitel 5.2.1.3 / 5.2.2). Auch die Kombination von faserverstärkten Substraten mit gängigen Spritzgußformmassen konnte umgesetzt werden.
Für alle Prozessschritte wurden Parameter-Wirkungs-Beziehungen erarbeitet und so optimierte Bedingungen für jeden einzelnen Verfahrensschritt ermittelt. Der Einfluss von Temperatur, Zeit und Druck auf die mechanischen Eigenschaften konnte ausführlich charakterisiert werden (s. Kapitel 5.3).
Durch die erfolgreiche Kombination der relevanten Eigenschaften von Thermoplasten und Duroplasten und der damit verbundenen Effizienzsteigerung des Herstellungsprozesses im Labor- und Industriemaßstab, wird mit der Evonik Industries AG eine Kommerzialisierung solch eines neuartigen Faserverbundmaterials angestrebt.The aim of this study was to combine the positive properties of thermoplastics (quick and easy thermal processing) and thermosets (good mechanical and thermal properties) in a single material to allow a more efficient production and use of fiber reinforced composites.
This goal was achieved through the development of a new cross-linking mechanism by Diels-Alder reaction of polyacrylate systems.
Based on extensive off-inition calculations for various model systems, the furfurylic-methacrylate (FuMA) and the meta-xylylene-bis-maleimide (MXBI) were chosen for the Diels-Alder reaction for this work. It was shown that the main thermal parameters correspond to the pre-defined requirements (s. Chapter 4.6). Based on the DSC curves and rheological studies, a glass transition temperature of about 100 ° C could be determined. Furthermore the reversibility of the reaction could be demonstrated with these methods. The inverse gel temperature, at which the material behaves as a thermoplastic melt, is depending on the selected functionality and lays between 130 °C and 185 °C (s. Chapter 4.5.2.1).
By addition with impact-modifiers and the exact adjustment of the molecular weights and of the Diels-Alder functionalities in the polymer, the mechanical properties are raised at the level of commercially available PMMA injection molding compounds (4.3ff chapter.). The mechanical behavior has been adjusted, so that the maximum strength of the Material appears in the range of the fiber failure, to produce an optimal synergic effect in the fiber reinforced composite material. In comparison to commercial available composites with reversibly linked or thermoplastic matrix, the developed composites shows significantly better mechanical properties (s. Chapter 4.6).
The efficiency of the thermally reversible cross-linking reaction under different conditions could be determined via density measurements and a comparison between theoretical and measured inverse gel point temperature (s. Chapter 4.5.1 / 4.5.2.1).
It could be demonstrated, that the mechanical properties of the developed polymer are on the same level as irreversible crosslinked thermosets. In Comparison to thermoplastics, the loss of the E-Modul is smaller (s. Chapter 4.4).
After the matrix development was completed with good properties, an efficient process for producing thermally reversible fiber reinforced plastics has been developed (Chapter 5.2.2 / 5.4). The Impregnation were done on a standard industry coating system with aqueous polymer dispersions. Because of the low viscosity of the dispersion, a very good impregnation quality could be obtained. The produced prepregs are already cross-linked and shows in contrast to e.g. Epoxy-amine prepregs a long storage stability at room temperature (s. Chapter 5.1).
Because of the lower molecular weight, the developed material shows a significantly lower viscosity in the melt during the processing (s. Chapter 4.2.1.2). Especially with regard to the production of fiber reinforced composites from prepregs, the lower viscosity (see chapter. 5.2.1.4 / 5.2.2) leads to a better connection of the prepreg layers and thus to a higher component quality with better properties.
In experiments on the double-diaphragm system of the IKV Aachen and by the production at an automotive supplier (Plastic Omnium) complex components could be prepared starting from the prepreg in cycle times of less than 60 seconds. The process is faster than for thermoset systems and is comparable to the cycle times in the production of thermoplastic composites. Furthermore a complete process step can be saved (s. Chapter 5.2.1.3 / 5.2.2). The combination of fiber-reinforced substrates with conventional injection moldings could be demonstrated as well.
It was possible to identify optimized process parameters for each process step. The influence of temperature, time and pressure on the mechanical properties are characterized in detail (s. Chapter 5.3).
Because of the successful combination of the relevant properties of thermoplastics and thermosets, and the associated increase in efficiency of the manufacturing process in the laboratory and industrial scale, such a material will be commercialized by Evonik Industries AG
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
- …
