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
Simulation und grundlegende Experimente zu Silizium-Dünnfilmen aus laserbearbeiteten Siliziumnanopartikeln
No full textDie waferbasierte Silizium-Halbleitertechnologie hat die Welt in den zurückliegenden Jahrzehnten mit ihrer rasanten Entwicklung maßgeblich geprägt und verändert. In den letzten Jahren wurde jedoch an Alternativen zu dieser Technik geforscht, da die klassische Silizium-Halbleitertechnologie auf Grund der eingesetzten Vakuumprozesse stets mit hohen Kosten verbunden ist. Eine kostengünstigere Alternative, die zurzeit große Aufmerksamkeit erfährt, sind druckbare Rolle zu Rolle Prozesse.
Daher wird in dieser Arbeit die Herstellung von Siliziumschichten aus excimerlaserbearbeiteten Siliziumnanopartikeln untersucht. Die Siliziumnanopartikel können dabei aus einem flüssigkeitsbasierten Prozess auf ein Substrat aufgebracht werden. Dies ermöglicht es die Eigenschaften von Silizium, wie z.B. eine hohe Ladungsträgerbeweglichkeit und eine geringe Degradation an der Atmosphäre, mit einem druckbaren Prozess zu kombinieren.
In einem ersten Schritt wurden dazu mit Hilfe einer Comsol Multiphysics® Simulation das Temperaturprofil während der Excimerlaserbearbeitung von Siliziumnanopartikeln auf einem Siliziumsubstrat beschrieben. Dazu wurde ein transientes eindimensionales Modell basierend auf der allgemeinen Wärmediffusionsgleichung entwickelt. Zur Modellierung wurden die spezifischen Materialparameter, wie Oberflächenreflexion bei λ=248 nm, der Schmelzpunkt und die Wärmeleitfähigkeit der Siliziumnanopartikelschicht, ermittelt. Um die Genauigkeit der Simulation zu validieren, wurde die aus dem Temperaturprofil ermittelte maximale Schmelztiefe, die während der Laserbearbeitung von dotierten Siliziumnanopartikeln auf einem einkristallinen Silizium-Substrat auftritt, mit dem experimentell mittels ECV-Messung gemessenen Dotierprofil verglichen.
Mit Hilfe der so evaluierten Simulation ist im Folgenden erfolgreich das Temperaturprofil während der Laserbearbeitung von Siliziumnanopartikeln auf ein Siliziumnitridbeschichteten Glassubstrat übertragen worden. Mit Hilfe der Simulation konnte gezeigt werden, dass die Temperatur des Siliziumnitrides bei geeigneter Wahl der Laserenergiedichte nicht aufschmilzt bzw. sublimiert und somit während des Laserprozesses strukturell stabil bleibt.
Als nächstes wurde der Prozess experimentell durchgeführt. Dabei zeigte es sich, dass es während der Laserbearbeitung nicht zur Bildung einer geschlossenen Fläche kommt sondern µ-Strukturen entstehen. Um die Entstehung dieser µ-Strukturen genauer zu verstehen, wurde eine zweidimensionales Comsol Multiphysics ® Modell, basierend auf der inkompressiblen Navier-Stokes-Gleichung, entwickelt. Dabei wurde der Kontaktwinkel zwischen dem Siliziumnitrid und dem flüssigen Silizium sowie die Porosität der Nanopartikel in einem Effektiven-Medium-Ansatz berücksichtigt. Die Simulation zeigte ein Entnetzen und die Bildung µ-Strukturen, wie sie zuvor auch bei experimentell hergestellten Proben beobachtet wurden. Mit Hilfe der Simulation konnten die drei Parameter Kontaktwinkel, Schmelzdauer und Porosität der Schicht identifiziert werden, die die schichtbildenden Eigenschaften maßgeblich beeinflussen.
Mit Hilfe der Simulation kann gezeigt werden, dass es wahrscheinlich möglich ist, aus der porösen Siliziumnanopartikelschicht mittels Excimerlaserbearbeitung eine geschlossene und 100% dichte Siliziumschicht zu erzeugen, wenn ein Substrat mit einem auf 55° reduzierten Nichtgleichgewichtskontaktwinkel genutzt wird und eine Reduktion der Schichtporosität auf unter 40% erreicht wird.In the last decades the rapid development in the area of electronic devices was defined by the continuing development in silicon wafer based semiconductor technology. High costs of the vacuum based processes used to fabricate electronic devices on silicon wafers alternative process techniques are for great interest for developing cost effective circuits. A promising alternative are printable semiconductors, which can be produced in a cost effective role to role process.
The forming of silicon thin films by the excimer laser annealing of dispersion processed silicon nanoparticles on non silicon substrates is one of the promising candidates for such a process. The process combines the advantages of classical silicon technology with a cost effective printable process.
In order to determine a suitable substrate a COMSOL Multiphyiscs simulation is used. As a first step the temperature profile was described in COMSOL Multiphysics using the heat diffusion equation. For this purpose system specific material parameters are determined such as the silicon nanoparticle melting point at 1683 K, the surface reflectivity at 248 nm of 20% and the nanoparticle thermal conductivity between 0.3 and 1.2 W/m∙K. To validate the model, the excimer laser process was first simulated on a silicon substrate. The comparison to experimental data obtained by Raman spectroscopy, Scanning electron microscopy (SEM) and electrochemical capacitance-voltage measurements (ECV). The experimental data are in good agreement with the theoretical findings and supports the validity of the model. In the following the model was extended to describe the laser process on a silicon nitride covered class substrate which is commonly used during laser annealing of silicon thin films.
The simulations on these substrates were experimentally validated. During the evaluation experiments it became clear that In contrast to their film forming properties on oxide free silicon substrates, the nanoparticle thin film tends to dewet and form a porous µ-structure on the silicon nitrite covered glass. The size and the distribution of the µ-structure in dependence of the laser energy density were quantified using a SEM study in conjunction with the image processing software ImageJ. To get a deeper understanding of the film forming process, a COMSOL Multiphysics ® fluid dynamics model, which solves the Navier Stokes equation for incompressible Newtonian fluids, was developed. To account for the porous nanoparticle thin film structure in the simulation, an effective medium approach is used by applying a conservative level set one phase method to the mesh. This effort allows predicting the Silicon melt film formation ranging from a porous Silicon µ-structure to a compact 100% density Silicon thin film in dependence of the substrate / thin film interaction as well as the laser energy used for the nanoparticle processing.
The simulation shows the possibility of forming a closed and 100% dense layer by laser annealing of a porous silicon nanoparticle thin film. Thereto the non equilibrium contact angle needs to be reduced to 55° and simultaneously the silicon nanoparticle layers porosity needs to be reduced to 40% or lower. Following this process technologies and methods to reduce the non equilibrium contact angle and the nanoparticle layer porosity are discussed. This shows that the forming of silicon thin films by the excimer laser annealing of dispersion processed silicon nanoparticles on non silicon substrates is a promising candidate for printable electronics
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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