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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
Alüminyum Titanat/La2O3 -Stabilize Edilmiş Zirkonya Seramiklerin Termal Özellikleri ve Mikroyapısal Karakterizasyonu
No full textBu yazıda, geleneksel seramik üretim yöntemleri ile imal edilen% 8 mol Lanthana (Lantanyum oksit, La2O) ile stabilize edilmiş Zirkonya (Zirkonyum Oksit, ZrO) esaslı kompozitlerin üretim ve yoğunlaşma davranışları anlatılmaktadır. , La2O3 ile Stabilize edilmiş (dengelenmiş) zirkonyum dioksit (LSZ, mol% 8 La2O3ile) termal darbeye karşı yüksek tolerans, düşük termal iletkenlik, mekanik özellikler, yüksek erime noktası, iyi bir faz dengesi ve mükemmel oksidasyon direnci gibi yüksek üstün sıcaklık özelliklerine sahiptir. Alüminyum titanat (Al2Ti05), erimiş metallerde iyi kimyasal dirençle birlikte, termal şok direnci ve düşük termal iletkenliğe sahiptir. Bu çalışmada, farklı yüzdelerdeki Al2TiO5 ile alüminyum titanat / LSZ seramikleri toz metalurjisi teknikleri kullanılarak hazırlandı. Mikroyapısal, mekanik ve termal özellikler XRD, SEM, dilatometre ve sertlik ile karakterize edildi. Hazırlanan seramiklerin suda soğutulmasıyla termal şok direnci davranışı da değerlendirildi. Sonuçlar, alüminyum titanatın LSZ matrisine eklenmesinin alüminyum titanat / LSZ seramiklerinin özelliklerini geliştirdiğini ortaya koyduIn this paper defined the productions and densiŞcation behaviour of 8 mole% Lanthana (Lanthanum oxide, La2O3) -stabilized Zirconia (Zirconium Oxide, ZrO2) based composites fabricated by the conventional ceramic production process. La2O3 stabilized zirconia (LSZ, with mole 8% La2O3) has excellent high temperature properties like low thermal conductivity, mechanical properties, elevated melting point, high toleration for thermal shock, superior oxidation resistance and well phase stability. Aluminium titanate (Al2TiO5) low thermal conductivity coupled with well chemical resistance in melted metals and exhibit extremely well thermal shock resistance. In this study, Aluminium titanate / LSZ ceramic with different proportions of Al2TiO5 was prepared by powder metallurgy techniques. The mechanical, thermal and microstructural properties were characterized by XRD, SEM, hardness and dilatometer. The thermal shock resistance performance under water quenching of the as-prepared ceramics was also estimated. As a results shown that the adding of aluminium titanate to LSZ matrix improves the properties of the aluminium titanate / LSZ ceramic
Thermal Properties and Microstructural Characterization of Aluminium Titanate (Al2TiO5) / La2O3 -Stabilized Zirconia (ZrO2) Ceramics
Get PDFIn this paper defined the productions and densification behaviour of 8mole% Lanthana (Lanthanum oxide, La2O3)-stabilized Zirconia (Zirconium Oxide, ZrO2) based composites fabricated by the conventional ceramic productionprocess. La2O3 stabilizedzirconia (LSZ, with mole 8% La2O3)has excellent high temperature properties like low thermal conductivity,mechanical properties, elevated melting point, high toleration for thermalshock, superior oxidation resistance and well phase stability. Aluminiumtitanate (Al2TiO5) low thermal conductivity coupled withwell chemical resistance in melted metals and exhibit extremely well thermalshock resistance. In this study, Aluminium titanate / LSZ ceramic withdifferent proportions of Al2TiO5 was prepared by powdermetallurgy techniques. The mechanical, thermal and microstructural properties were characterized by XRD, SEM, hardnessand dilatometer. The thermal shock resistance performance under water quenchingof the as-prepared ceramics was also estimated. As a results shown that theadding of aluminium titanate to LSZ matrix improves the properties of thealuminium titanate / LSZ ceramics
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
Binder removal and characterization of zirconia ceramics prepared by hot molding
Get PDFSeramik tozlarının çeşitli şekillendirilme yöntemleri vardır. Bu yöntemler soğuk veya sıcak, yaş veya kuru olmak üzeri çeşitli şekillerde sınıflandırılabilir. Bu çalışmada, mühendislik seramiklerinin şekillendirilmesinde diğer şekillendirme yöntemlerine nazaran daha düşük maliyetli ve daha kolay bir üretim prosesine sahip yeni bir şekillendirme yöntemi denenmiştir. Bu yöntem iki farklı şekillendirme yönteminin birleştirilmesi esasına dayanır. Yaş döküm yöntemi ile enjeksiyon kalıplama yönteminin birleşimi şeklindedir. Polimer katkılı sıcak akışkan seramik toz karışımı bir kalıp içine basınç uygulamadan dökülerek şekillendirilir. Zirkonya (ZrO2), magnezya (MgO) ve kalsiya (CaO) tozlarından farklı bileşimlerde mekanik alaşımlama tekniği ile karışımlar hazırlanmıştır. Bağlayıcı sistemi, parafin (%95 ağ.) ve oleik asit (%5 ağ.) olan, hacimce %60 bağlayıcı ve %40 seramik tozu içeren karışımlardan basınçsız sıcak şekillendirme yöntemiyle numuneler hazırlanmıştır. Hazırlanan numunelerden bağlayıcı giderme çalışmalarında iki kademeli bir işlem kullanılmıştır. Bağlayıcı giderme çalışmalarının ilk aşamasına ait şartlar, 120°C’de 5 saat olarak belirlenmiştir. Ağırlıkça yaklaşık %33 bağlayıcı giderilen söz konusu şartlar, çalışılan tüm numunelere uygulanmıştır. İkinci aşamada ise, geri kalan bağlayıcı, atmosfer şartlarında bağlayıcı giderme fırınında 600°C’nin al-tında tamamen giderilmiştir. Bu işlem tamamlandıktan sonra numuneler, 1600°C’de 3 saat sinterlenmiş ve oda sıcaklığına soğutulmuştur. Sinterlenmiş bazı numuneler 1450°C’de 4 saat yaşlandırmaya bırakılmıştır. Sinterlenmiş numunelerin XRD ve SEM kullanılarak faz analizi ve mikroyapısal karakterizasyonu yapılmıştır. Anahtar Kelimeler: Stabilize zirconia, basınçsız sıcak şekillendirme, bağlayıcı giderme, sinterleme, karakterizasyon.Oxide ceramics include alumina, zirconia, silica, aluminum silicate, magnesia and other metal oxide based materials. Oxide ceramics have high melting points, low wear resistance, and a wide range of electrical properties. Oxide ceramics are used in a variety of applications. Examples include chemical and materials processing, electrical and high voltage power applications, Radio Frequency (RF) and microwave applications, and foundry and metal processing. "Zirconia-Ceramic steel" The title of the first scientific paper to highlight the possibilities offered by the "transformation toughening" mechanism which occurs in certain zirconia ceramics. Since the publication of this seminal work in 1975, considerable research, development, and marketing efforts have been expanded on this single material which offer the traditional ceramic benefits of hardness, wear resistance and corrosion resistance, without the characteristic ceramic property of absolute brittleness. Zirconia, ZrO2 exists as a monoclinic crystal at room temperature inverting to tetragonal phase above approximately 1200°C. The addition of large amounts of a stabilizer such as magnesium oxide will induce a cubic crystal structure during firing that does not revert to the monoclinic phase upon cooling. The addition of generally less than 10% by weight of stabilizers yields high-density ceramic bodies known as transformation toughened zirconia. Two fundamentally different microstructures exist depending upon the added stabilizer. The addition of MgO yields a relatively coarse grained (50-100 micron) microstructure known as Mg-PSZ. The grains are predominantly cubic morphology with a fine precipitate of tetragonal phase dispersed within the grain. Yttria, Y2O3, additions yield an extremely fine grained (less than 1 micron) microstructure known as Y-PSZ or TZP or tetragonal zirconia polycrystal. The individual grains are completely tetragonal. In present study, Calcia and Magnesia stabilized fine Zirconia powders in various ratios were studied. Powder mixtures (Ca(OH)2, Mg(OH)2 and ZrO2) were prepared in acetone and milled as wet with YSZ (yitria stabilized zirconia) balls of 10 mm Ø for 3 h. Particle size of Calcia, Magnesia and Zirconia powders were submicrometer. The pressureless hot molding technique has been selected for forming of the partial stabilized zirconia with MgO and CaO. Binder system for pressureless hot molding was a mixture of paraffin wax as primary binder and oleic acid as surfactant. Paraffin wax/oleic acid ratio was maintained at a value close to 95/5 as weight. Typical feedstock contained 40 vol. % ceramic powders, and 60 vol. % binder phases. A two-step process was used for debinding of green samples. In wicking step by capillary action, samples embedded in same ZrO2 powder in a copper box were put in an furnace in the 120, 150 and 180°C temperatures for 1, 3, 5 and 10 hours. The variation of sample weight with temperature and time was measured to calculate the debinding ratio. In the second step of debinding process, partially debinded samples were heated to 600°C at a slow heating rate. After completing this process, green ceramics were fired at 1600 °C for 3 hours in an electric-heated furnace and then cooled quickly. Some of the fired ceramics were aged in the same furnace for 4 hours at 1450 °C. After annealing, the some specimens were sectioned, ground, polished to 1 mm surface-finish and finally thermally etched in air for 30 min. at a temperature 1420 °C. The density and porosity of sintered samples were measured by Archimedes principle. The microstructural characterization of the sintered samples was carried out using scanning electron microscopy. The morphological parameters of the various phases were characterized by using a semiautomatic image analyzer, EDS and the formed phases were analyzed by X-ray powder diffractometer using Co K? radiation. Ca-ZrO2 and Mg-ZrO2 ceramics have been prepared by solid state reaction synthesis. The beneficial effects on the binder removal, microstructural characterization and phase structure of zirconia ceramics prepared by pressureless hot molding have been analyzed. t- ZrO2 and c- ZrO2 phase value increased with the addition of Calcia (CaO) and fired temperature and time. The addition of Calcia (CaO) to Zirconia (ZrO2) matrix the highest the value of t- ZrO2 and c- ZrO2. Keywords: Stabilized zirconia, pressureless hot molding, debinding, sintering, characterization
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