1,721,025 research outputs found
Effect of local and global connectivity of phases on damage evolution in cast Al-Si Alloys
Full text linkThe strength and damage behavior of Aluminum-Silicon piston alloys during external mechanical loading is determined by the mechanical and physical properties of the 3D architecture of Si and intermetallics, their thermal/mechanical stability and their geometrical arrangement (volume fraction, size, morphology, distribution, interconnectivity, contiguity), which may vary during production and service. The advance of modern characterisation methods that allow to observe the evolution of the microstructure in situ and/or three-dimensionally, provide new insights crucial for the case of complex microstructures. In this thesis, with the implementation of state of the art ex-situ and in-situ x-ray and synchrotron x-ray tomography methods complemented by 2D metallography investigations, microstructural features affecting strength and damage mechanisms during ambient and elevated temperature tensile deformation as a function of chemical composition and heat treatment were univocally identified. Also, a quantitative relationship between 3D architecture of the investigated Al-Si alloys and microstructural features affecting the damage processes during external loading could be established
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Experimental analysis and modelling of the precipitation kinetics of the Ni-based superalloy Haynes 282
Full text linkDie Multi-Ausscheidungskinetik der neuen Nickelbasis - Superlegierung Haynes 282 wurde mittels Lichtmikroskopischen und Rasterelektronenmikroskopischen Untersuchungen und anschließenden Simulationen mit MatCalc analysiert. Über Korngrößenanalysen und EDX - Analysen der entstandenen Ausscheidungen wurde der Einfluss verschiedener Wärmebehandlungen und unterschiedlicher Umformgrade des Materials eingehend untersucht. Das untersuchte Material mit Umformgraden von =0,1;0,7 & 1 nach dem Schmieden wurde verschiedenen Wärmebehandlungen unterzogen, um Veränderungen der Mikrostruktur und deren Zusammenhang mit den mechanischen Eigenschaften, insbesondere der Bruchdehnung, des Werkstoffes zu evaluieren. Die Proben wurden bei 1107°C und 1115°C Lösungsgeglüht und mit verschiedenen Abkühlraten (air cooling vs. water quenching) auf Raumtemperatur abgekühlt. Darauf folgte ein Intermediate Ageing bei 996°C bzw. 1010°C für verschiedene Zeiten und entweder ein Final Ageing bei 788°C für acht Stunden oder ein zweistufiges Final Ageing bei 760°C für fünf Stunden, ein zweistündiges Abkühlen auf 650°C im Ofen und eine weitere Stunde auf dieser Temperatur. Für das Kornwachstum schien hauptsächlich das Lösungsglühen verantwortlich zu sein. Ein Lösungsglühen bei y` - super-solvus - Temperaturen hatte ein Kornwachstum von bis zu 360% bezogen auf den Mittelwert und vollkommen rekristallisiertes Gefüge zur Folge. Es konnte eine Temperaturgrenze für das Kornwachstum zwischen 1010°C und 1107°C festgestellt werden. Es konnte eine starke Abhängigkeit der Ausscheidungskinetik von der Abkühlrate nach dem Schmieden/Lösungsglühen festgestellt werden. Hohe Intermediate Ageing Temperaturen erzeugten grobe y` - Teilchen, die hohe Bruchdehnungen zur Folge haben sollten. Mit steigenden Haltezeiten (30,60,120 und 180min) und höheren Umformgraden konnte ein deutlicher Anstieg an sekundären Karbiden, die sich semi-kontinuierlich bis kontinuierlich an den Korngrenzen abschieden vermerkt werden. Reduzierte Bruchdehnung nach Zugversuchen bei gleichen Wärmebehandlungen wurde auf zeilige, grobe Karbide im Gefüge und womöglich auf ein ausgeprägteres Duplexgefüge zurückgeführt. Simulationen der Ausscheidungskinetik ausgewählter Wärmebehandlungsrouten standen weitestgehend im Einklang mit den Experimenten. Basierend auf den experimentellen Ergebnissen und den Simulationen mit MatCalc wurden einige Proben, die besonders niedrige oder hohe Bruchdehnungen aufweisen sollten aus der Probenreihe herausgesucht.The multi - precipitation kinetics of the new Ni-base - superalloy Haynes 282 was investigated using light microscopiy and SEM analysis, followed by simulations with MatCalc. The influence of different heat treatments and deformations on the micristructure was thoroughly investigated by means of grain size analysis and SEM/EDX - analysis of the formed precipitates. The investigated material with initial deformations of =0,1;0,7 & 1 was subjected to different heat treatments to evaluate the microstructural changes and their correlation with mechanical properties, in particular the elongation at fracture. The samples were solution annealed at 1107°C or 1115°C and cooled down to room temperature at different cooling rates (water quench vs. air cooling). This was followed by intermediate ageing at 996°C or 1010°C. And final ageing at 788°C for 8 hours or a two-step final ageing at 760°C for five hours, two hours furnace cooling to 650°C and air cooling to room temperature after one hour at this temperature was applied. Solution annealing above y- - solvus - temperatures resulted in grain growth up to 360% based on the mean grainsize and fully recrystallized microstructures. There seemed to be a temperature boundary for grain growth between 1010°C and 1107°C. A strong influence of the cooling rate after forging/solution annealing on the precipitation kinetics could be observed. High intermediate temperatures produced coarse y- precipitates, which should result in high elongation values. With increasing ageing times (30, 60, 120 & 180min) and higher deformation degrees higher amounts of secondary carbides could be detected distributed semi-continuously to continuously along the grain boundaries. Reduced elongation after tensile testing with same heat treatment was attributed to the band formation of coarse precipitates and possibly to the existence of duplex microstructures. Simulations of the precipitation kinetics of selected heat treatments were mostly in agreement with the experimental data. Based on the experimental results and the simulations conditions that should lead to large/small elongation at fractures were selected
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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