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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
Das Potenzial von Perowskiten entfesseln: Synergistische Optimierung von Zusammensetzung, Grenzflächen und eingebauter Spannung für Hochleistungs-Solarzellen
No full textThis thesis focuses on the development of high-performance perovskite solar cells, a promising photovoltaic technology with the potential to meet increasing global energy demands. Perovskite solar cells have garnered significant attention due to their exceptional properties and rapid advancements in recent years. While perovskite solar cells have shown impressive efficiencies in laboratory settings, further improvements are needed to surpass existing commercial technologies like silicon-based solar cells. This thesis explores the fundamental principles of solar energy conversion and perovskite solar cell operation and presents key findings from experimental investigations aimed at enhancing device efficiency and understanding the underlying physics.
A brief overview of solar energy conversion and semiconductor physics is provided, covering essential concepts such as blackbody radiation, band theory, charge carrier dynamics, and p-n junction behavior. The unique properties of perovskite materials are highlighted, including their excellent light absorption capabilities, long charge carrier diffusion lengths, and tunable bandgap energy. The importance of interface engineering in perovskite solar cells is emphasized, as interfaces play a critical role in charge extraction, recombination losses, and overall device stability. The impact of mobile ions within perovskites is also discussed, along with strategies for mitigating ion migration and enhancing device stability.
The experimental work presented in this thesis focuses on three main areas. First, a novel fabrication method for large-grain double-cation perovskite films is demonstrated. These films exhibit an impressive 18.2 µs carrier lifetime and high external photoluminescence quantum yields of 20%, indicating excellent optoelectronic quality. Incorporating these films into inverted perovskite solar cell architectures leads to improved device performance, achieving short-circuit currents exceeding 24 mAcm-2. Intensity-dependent measurements suggest an implied efficiency of 28.4% is achievable in the neat material by minimizing interfacial recombination and optical losses.
Next, the thesis investigates the effects of incorporating methylammonium chloride into two-step double-cation perovskite solar cells. Results show that MACl enhances both the photoluminescence quantum yield and PCE of these devices, with fabricated solar cells exhibiting PCEs ranging from 15-21%. The observed improvements are attributed to several factors, including increased grain size, enhanced light soaking stability, and a slight blue-shift in the perovskite bandgap energy. Devices with higher MACl content also show faster VOC saturation under illumination, indicating improved stability.
Finally, the thesis addresses the VBI in perovskite solar cells, a crucial aspect of device operation. By employing layer-by-layer SPV measurements, the study provides insights into the contribution of individual layers to the overall VBI. Results indicate that the largest contribution to the SPV originates from the top metal electrode, suggesting that the VBI in these devices is largely determined by the work function difference of the electrodes.
This thesis contributes to the understanding and development of efficient and stable perovskite solar cells by exploring novel fabrication techniques, investigating the impact of material modifications, and elucidating the role of the VBI in device operation. The findings presented here pave the way for further advancements in perovskite photovoltaic technology, bringing us closer to a future powered by clean and sustainable energy.Diese Dissertation konzentriert sich auf die Entwicklung leistungsstarker Perowskit-Solarzellen, einer vielversprechenden Photovoltaik-Technologie mit dem Potenzial, den steigenden globalen Energiebedarf zu decken. Perowskit-Solarzellen haben aufgrund ihrer außergewöhnlichen Eigenschaften und schnellen Fortschritte in den letzten Jahren erhebliches Interesse geweckt. Obwohl Perowskit-Solarzellen im Labor beeindruckende Wirkungsgrade gezeigt haben, sind weitere Verbesserungen erforderlich, um bestehende kommerzielle Technologien wie Silizium-basierte Solarzellen zu übertreffen. Diese Arbeit untersucht die grundlegenden Prinzipien der Solarenergiekonversion und den Betrieb von Perowskit-Solarzellen und präsentiert wichtige Erkenntnisse aus experimentellen Untersuchungen zur Effizienzsteigerung und zum Verständnis der zugrunde liegenden Physik.
Ein kurzer Überblick über die Solarenergiekonversion und die Halbleiterphysik wird gegeben, wobei wesentliche Konzepte wie Schwarzkörperstrahlung, Bändertheorie, Ladungsträgerdynamik und das Verhalten der p-n Übergänge behandelt werden. Die einzigartigen Eigenschaften von Perowskit-Materialien werden hervorgehoben, einschließlich ihrer hervorragenden Lichtabsorptionsfähigkeit, langen Ladungsträgerdiffusionslängen und einstellbaren Bandlückenenergie. Die Bedeutung des Interface-Engineering in Perowskit-Solarzellen wird betont, da Grenzflächen eine entscheidende Rolle bei der Ladungsextraktion, Rekombinationsverlusten und der allgemeinen Stabilität des Geräts spielen. Der Einfluss mobiler Ionen innerhalb der Perowskite wird ebenfalls diskutiert, zusammen mit Strategien zur Minderung der Ionenmigration und zur Verbesserung der Stabilität des Geräts.
Die experimentelle Arbeit in dieser Dissertation konzentriert sich auf drei Hauptbereiche. Erstens wird eine neuartige Herstellungsmethode für großkörnige Doppel-Kation-Perowskit-Filme demonstriert. Diese Filme zeigen eine beeindruckende Ladungsträgerlebensdauer von 18,2 μs und hohe externe Photolumineszenz-Quantenausbeuten von 20 %, was auf eine hervorragende optoelektronische Qualität hinweist. Die Einbindung dieser Filme in invertierte Perowskit-Solarzellen-Architekturen führt zu einer verbesserten Geräteleistung und erreicht Kurzschlussströme von über 24 mAcm⁻². Intensitätsabhängige Messungen deuten darauf hin, dass eine implizierte Effizienz von 28,4 % im reinen Material erreichbar ist, indem Grenzflächenrekombination und optische Verluste minimiert werden.
Im nächsten Schritt untersucht die Arbeit die Auswirkungen der Zugabe von Methylammoniumchlorid (MACl) in zweistufige Doppel-Kation-Perowskit-Solarzellen. Die Ergebnisse zeigen, dass MACl sowohl die Photolumineszenz-Quantenausbeute als auch den Wirkungsgrad (PCE) dieser Geräte verbessert, wobei hergestellte Solarzellen PCE-Werte im Bereich von 15–21 % aufweisen. Die beobachteten Verbesserungen werden auf mehrere Faktoren zurückgeführt, einschließlich erhöhter Korngröße, verbesserter Lichtstabilität und einer leichten Blauverschiebung der Perowskit-Bandlückenenergie. Geräte mit höherem MACl-Gehalt zeigen auch eine schnellere VOC-Sättigung unter Beleuchtung, was auf eine verbesserte Stabilität hindeutet.
Abschließend befasst sich die Arbeit mit der internen Spannungsverteilung (VBI) in Perowskit-Solarzellen, einem entscheidenden Aspekt des Gerätebetriebs. Durch die Anwendung von Schicht-für-Schicht-SPV-Messungen liefert die Studie Einblicke in den Beitrag der einzelnen Schichten zur gesamten VBI. Die Ergebnisse zeigen, dass der größte Beitrag zur SPV von der oberen Metallelektrode stammt, was darauf hindeutet, dass die VBI in diesen Geräten weitgehend durch den Unterschied der Arbeitsfunktionen der Elektroden bestimmt wird.
Diese Dissertation trägt zum Verständnis und zur Entwicklung effizienter und stabiler Perowskit-Solarzellen bei, indem sie neuartige Herstellungstechniken erforscht, die Auswirkungen von Materialmodifikationen untersucht und die Rolle der VBI im Gerätebetrieb beleuchtet. Die hier vorgestellten Ergebnisse ebnen den Weg für weitere Fortschritte in der Perowskit-Photovoltaik-Technologie und bringen uns der Zukunft einer sauberen und nachhaltigen Energieversorgung näher
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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