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Effect of grain refiners on the refining performance in aluminum wrought AA6111 alloys
Get PDFGiven the critical role of grain refinement in improving the castability and materials properties of wrought aluminum alloys, this project aims to optimize the grain refinement practice in aluminum casthouses. Efforts have been made to present a number of key points to consider when refining the 6111 wrought aluminum alloys, highlighting the potent grain refiners in terms of their efficiency. Moreover, comparisons were made based on the refiner potency in the grain size reduction, the resistance to the hot tearing and the reaction with the poisoning solutes. For these reasons, the present work is divided into two main parts. In the first part, the effects of different grain refiners (Al-3Ti-1B, Al-5Ti-1B and Al-3Ti-0.15C) on the grain size and morphology as well as hot tearing of 6111 aluminum alloy were investigated, taking in account of the direct chill casting parameters: grain refiner addition rates (1, 2 and 3Kg/T), Ti addition, and cooling rates (0.4 and 4°C/s). It was found that all three grain refiners can effectively reduce the grain size of 6111 alloy, and the Al-5Ti-1B refiner is the most effective in all conditions. The microstructure characterization of the refiner master alloys revealed that Al-5Ti-1B refiner had bigger Al3Ti particles, higher number density of TiB2 particles with more reasonable size distribution than the Al-3Ti-1B and Al-3Ti-0.15C refiners. With the increase of the refiner addition, the morphologies of the grains evolved from dendrite, cellular to globular morphology. Moreover, in addition to the grain refiner, the addition of titanium as solutes and the high cooling rate were beneficial to further grain size reduction. The grain refiners had also significant impact on hot tearing susceptibility in 6111 alloy. When the grain morphologies are dendritic, the addition of the grain refiner decreased the hot tearing susceptibility. However, a further refiner addition resulted in an increase of the hot tearing susceptibility despite the very small grains. In the second part, the poisoning effect of Cr on the grain refinement was investigated in 6111 aluminum alloys. The present work has taken in account of the DC casting parameters: Two cooling rates (0.4 and 4°C/s), Ti addition, three different grain refiners (Al-3Ti-1B, Al-5Ti-1B and Al-3Ti-0.15C) with different addition rates (1, 2 and 3Kg/T). It was found that a high concentration of Cr had a poisoning effect on the grain refinement, resulting in a coarse grain structure in all three grain refiners. SEM- EDS results revealed that the 3 kinds of intermetallics in the refiners (Al3Ti, TiB2 and TiC) could contain Cr in the particles surface. Higher % of Cr was always found in the Al3Ti particle surface compared to TiB2 and TiC particles, showing that Al3Ti particles were the most likely compound to be affected by such reaction with Cr. The Cr diffusion in the particles was found to increase with increasing the holding time. After that, the edge-to-edge matching model (E2EM) has been applied to examine the interfacial crystallographic matching between Al and intermetallic particles before and after Cr diffusion. Results based on E2EM calculations showed that the Cr diffusion into Al3Ti and TiC particles reduced the crystallographic matching of the particles with Al matrix, resulting in poor refinement efficiency. Coupling the present results with findings in literature, poisoning mechanisms were proposed to explain the Cr poisoning effect.
Étant donné le rôle critique d’affinage des grains dans l’amélioration de la coulabilité et des propriétés des alliages d’aluminium corroyés, ce projet vise à optimiser la pratique d’affinage des grains dans les fonderies d’aluminium. Des efforts ont été dédiés pour déterminer les facteurs clés à considérer lors de l’affinage des alliages d’aluminium corroyés 6111, tout en mettant l’accent sur les puissants raffineurs des grains. De plus, des études comparatives ont été établies sur le pouvoir affinant des raffineurs en termes de la réduction de la taille des grains, la résistance à la fissuration à chaud et la réaction avec les solutés empoisonnants. Pour ces raisons, le présent travail est divisé en deux grandes parties. Dans la première partie, les effets de différents raffineurs de grains (Al-3Ti-1B, Al-5Ti-1B et Al-3Ti-0.15C) sur la taille et la morphologie des grains ainsi que sur la fissuration à chaud de l'alliage d'aluminium 6111 ont été étudiés, tout en tenant compte des paramètres de la coulée semi-continue à refroidissement direct (Direct Chill): taux d'ajout du raffineur de grain (1, 2 et 3Kg/T), ajout de Ti, et vitesse de refroidissement (0,4 et 4°C/s). Les résultats ont prouvé que les trois raffineurs des grains peuvent réduire efficacement la taille des grains de l'alliage 6111, et le raffineur Al-5Ti-1B est le plus efficace dans toutes les conditions. La caractérisation de la microstructure des alliages mères des raffineurs a révélé que le raffineur Al-5Ti-1B avait de plus grosses particules d'Al3Ti, une densité numérique plus élevée de particules de TiB2 avec une distribution de taille plus raisonnable que les raffineurs Al-3Ti-1B et Al-3Ti-0.15C. Avec l'augmentation de l'ajout de raffineur, les morphologies des grains ont évolué d'une morphologie dendritique, cellulaire à globulaire. De plus, en plus du raffineur de grain, l'ajout de titane sous forme de soluté avec une vitesse de refroidissement élevée ont été bénéfiques pour une réduction supplémentaire de la taille des grains. Les raffineurs de grain ont également eu un effet significatif sur la susceptibilité à la fissuration à chaud de l'alliage 6111. Lorsque la morphologie des grains est dendritique, l'ajout du raffineur des grains a diminué la susceptibilité à la fissuration à chaud. Cependant, un ajout supplémentaire de raffineur a entraîné une augmentation de la susceptibilité à la fissuration à chaud malgré la taille très petite des grains. Dans la deuxième partie, l'effet d'empoisonnement du Cr sur l’affinage des grains a été étudié dans les alliages d'aluminium 6111. Le présent travail a pris en compte les paramètres de la coulée semi-continue à refroidissement direct (Direct Chill): deux vitesses de refroidissement (0,4 et 4 °C/s), ajout de Ti, trois affineurs de grains différents (Al-3Ti-1B, Al-5Ti-1B et Al-3Ti-0,15C) avec différents taux d'addition (1, 2 et 3Kg/T). Il a été constaté qu'une concentration élevée de Cr avait un effet d'empoisonnement sur l’affinage des grains, entraînant une structure à gros grains dans les trois raffineurs de grain. Les résultats SEM-EDS ont révélé que les 3 types d'intermétalliques présents dans les raffineurs (Al3Ti, TiB2 et TiC) pourraient contenir du Cr à la surface des particules. Un pourcentage plus élevé de Cr a été trouvé toujours à la surface des particules d'Al3Ti par rapport aux particules de TiB2 et TiC, ce qui montre que les particules d'Al3Ti étaient le composé le plus susceptible à une telle réaction avec le Cr. Il s'est avéré que la diffusion de Cr dans les particules augmente avec l'augmentation du temps de maintien. Après cela, le modèle d'appariement bord à bord (E2EM) a été appliqué pour examiner l'appariement cristallographique interfacial entre Al et les particules intermétalliques avant et après la diffusion de Cr. Les résultats basés sur les calculs (E2EM) ont montré que la diffusion de Cr dans les particules Al3Ti et TiC réduisait l'appariement cristallographique des particules avec la matrice Al, entraînant une faible efficacité d’affinage. Couplant les présents résultats avec les études de la littérature, des mécanismes d'empoisonnement ont été proposés pour expliquer l'effet d'empoisonnement au Cr
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
Başarılı Marka Oluşumunun Tüketici Davranışı ve Bağlılık Üzerindeki Etkisi
No full text▪ Yüksek lisans tezi.The study explores the relationship between successful branding and consumer behavior and customer loyalty. Branding is essential in today's rapidly evolving marketplace, affecting customer behavior and purchasing decisions. This research interprets the factors influencing consumer behavior and purchasing decisions and their association with successful branding. The approach utilizes a quantitative research method. The sample comprises 250 respondents, with a comprehensive questionnaire as the data collection tool. SPSS software (IBM SPSS Statistics 28) quantifies the data using frequency, reliability, EFA validity, t-test, correlation, and regression. The study reveals a positive relationship between successful branding, consumer behavior, and customer loyalty. This finding is beneficial for marketing professionals to understand branding's significance, allowing them to make informed decisions about brand management, marketing campaigns, and customer engagement methods. The research aids practitioners to enhance branding efforts and foster long-term customer relationships. Effective branding is crucial for influencing consumer behavior and encouraging client loyalty. The relationship between branding and customer outcomes is explored using quantitative techniques and SPSS software analysis. The study offers marketers information to improve brand management strategies and nurture enduring client relationships.Bu çalışma, başarılı markalaşma ile tüketici davranışı ve müşteri sadakati arasındaki ilişkiyi inceler. Markalaşmanın müşteri davranışını etkilemesi ve günümüz pazarında hayati önem taşıması üzerine odaklanır. Tüketici davranışını ve satın alma kararlarını etkileyen faktörlerin markalaşma ile ilişkisi yorumlanır. Çalışma, nicel bir araştırma yöntemi ve kapsamlı bir anket kullanır. 250 yanıtlayıcıdan oluşan örneklem kullanılmıştır. IBM SPSS Statistics 28 ile veriler analiz edilmiştir. Çalışma, başarılı markalaşma, tüketici davranışı ve müşteri sadakati arasında pozitif bir ilişki olduğunu gösterir. Pazarlama profesyonelleri için markalaşmanın önemini anlamada yardımcıdır. Araştırma, uygulayıcılara markalaşma çabalarını geliştirme ve uzun vadeli müşteri ilişkilerini teşvik etme konusunda destek sağlar. Etkili markalaşmanın tüketici davranışını etkileme ve müşteri sadakatini teşvik etme üzerindeki etkisi tartışılır. Markalaşma ve müşteri sonuçları arasındaki ilişki, nicel teknikler kullanılarak analiz edilir. Çalışma, pazarlamacılara marka yönetimi stratejilerini geliştirme ve müşteri ilişkilerini sürdürme konusunda bilgi sunar
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
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