1,720,953 research outputs found
Mavi ışık yayan diyotların ve beyaz ışık dönüşümünün termal ve optik özelliklerine dair bir inceleme.
No full textThe evolution of lighting technologies has progressed from primitive fire-based sources to advanced solid-state devices, with Light-Emitting Diodes (LEDs) emerging as a cornerstone of modern illumination due to their energy efficiency and versatility. However, the performance and longevity of LEDs are critically dependent on effective thermal management, as excessive heat generation can degrade efficiency and lead to premature failure. This work examines natural convection heat transfer from millimetric surfaces using LED chip packages as a representative system. Experiments were conducted at electrical currents between 40–120 mA, measuring junction and fluid temperatures, and results were validated against CFD simulations with good agreement. Analysis revealed that conventional Nusselt number correlations deviate significantly at this scale, particularly for horizontal and vertical chip surfaces. This study examines the thermal–optical behavior of phosphor-converted LEDs using experimental testing and CFD modeling. LED packages with phosphor concentrations of 0.99 wt.%, 1.3 wt.%, and 2.98 wt.% were fabricated and tested under controlled conditions. Junction temperatures and chromaticity coordinates were measured, while a validated CFD model reproduced the results. At 0.99 wt.%, the CIE coordinates were approximately (0.26, 0.21). When the phosphor loading was increased to 1.3 wt.%, the CIE coordinates shifted to about (0.3, 0.26). At the highest concentration of 2.98 wt.%, the junction temperature rose by ~1.7 °C, and the CIE coordinates changed further to around (0.43, 0.44). The agreement between experiments and simulations confirms the accuracy of the modeling approach and shows the direct relationship between phosphor loading, junction heating, and chromaticity shift. The findings underscore the importance of optimizing thermal management strategies for LEDs, particularly in high-power applications. The study contributes to the advancement of LED technology by providing insights into heat dissipation mechanisms and proposing practical solutions for enhancing optical and thermal performance for the added benefits of reliability.Aydınlatma teknolojilerinin evrimi, ilkel ateş tabanlı kaynaklardan gelişmiş katı hâl aygıtlarına kadar ilerlemiş olup, enerji verimliliği ve çok yönlülüğü sayesinde Işık Yayan Diyotlar (LED’ler) modern aydınlatmanın temel taşlarından biri hâline gelmiştir. Bununla birlikte, LED’lerin performansı ve ömrü, etkin bir ısıl yönetim uygulamasına kritik düzeyde bağlıdır; zira aşırı ısı üretimi, verimliliğin azalmasına ve erken arızalara yol açabilmektedir. Bu çalışma, LED çip paketleri temsilî bir sistem olarak kullanılarak milimetrik yüzeylerden doğal taşınımla gerçekleşen ısı transferini incelemektedir. Deneyler, 40–120 mA arası elektrik akımlarında gerçekleştirilmiş, eklem (junction) ve akışkan sıcaklıkları ölçülmüş ve sonuçlar Hesaplamalı Akışkanlar Dinamiği (HAD) benzetimleri ile doğrulanmış, iyi bir uyum gözlenmiştir. Analizler, geleneksel Nusselt sayısı korelasyonlarının bu ölçekte, özellikle yatay ve dikey çip yüzeylerinde önemli sapmalar gösterdiğini ortaya koymuştur. Bu çalışma ayrıca, deneysel testler ve HAD modellemesi kullanılarak fosfor dönüştürmeli LED’lerin ısıl-optik davranışını incelemektedir. Ağırlıkça %0.99, %1.3 ve %2.98 fosfor içeriğine sahip LED paketleri üretilmiş ve kontrollü koşullarda test edilmiştir. Eklem sıcaklıkları ve renk koordinatları ölçülmüş, doğrulanmış HAD modeli sonuçları yeniden üretmiştir. %0.99 fosfor yüklemesinde CIE koordinatları yaklaşık (0.27, 0.22) bulunmuştur. Fosfor yüklemesi %1.3’e çıkarıldığında koordinatlar yaklaşık (0.30, 0.26)’e kaymıştır. En yüksek yoğunluk olan %2.98’de eklem sıcaklığı yaklaşık 1.7 °C artmış, CIE koordinatları ise yaklaşık (0.43, 0.44)’e değişmiştir. Deneyler ile simülasyonlar arasındaki uyum, modelleme yaklaşımının doğruluğunu teyit etmekte ve fosfor yüklemesi, eklem ısınması ve renk kayması arasındaki doğrudan ilişkiyi göstermektedir. Elde edilen bulgular, özellikle yüksek güçlü uygulamalarda LED’ler için ısıl yönetim stratejilerinin optimize edilmesinin önemini vurgulamaktadır. Bu çalışma, ısı dağılım mekanizmalarına ilişkin kavrayış sağlayarak ve optik ile ısıl performansı artırmaya yönelik pratik çözümler önererek LED teknolojisinin gelişimine katkıda bulunmaktadır
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
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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