1,720,985 research outputs found
Effect of Fe and O on the Continuous Cooling Beta and Alpha Transformation Behaviors of Pure-Ti
No full textOptical frequency-domain reflectometry based on wavelength-swept mode-locked fiber laser
No full textWe demonstrate a novel optical frequency-domain reflectometry system with compactness and short measurement time based on the use of a wavelength-swept mode-locked fiber laser. The optical source uses an intracavity tunable Fabry-Perot filter as a tuning element. The fiber laser sweeps 20 nm in less than 10 ms. Spatial resolution of 100 pm and total measurement range of several centimeters are demonstrated.The authors would like to thank Dr. H. K. Kim and Dr. S. H.
Yun for support and valuable discussions
Continuous-cooling alpha-to-gamma transformation behaviour of Ti-45.5 at.% Al-0.05 at.% B alloy
No full textThe continuous-cooling transformation behaviour of Ti - 45.5 at.% Al-0.05 at.% B alloy was quantitatively measured using a real-time resistivity temperature - time measurement apparatus operating under a high vacuum. The addition of a small amount of B does not significantly alter the alpha - gamma-phase equilibria but significantly raises the alpha - gamma lamellar start temperature of Ti - 45.5 at.% Al alloy at most cooling rates. Furthermore, it markedly increases the critical cooling rate for the ordering reaction. The effect of B addition, which greatly stabilizes the lamellar structure up to a fast cooling rate, is to accelerate the lamellar formation kinetics; the lamellar spacing was nevertheless distinctively larger in a B-doped alloy. This is because lamellae in B-doped alloy nucleate heterogeneously on titanium borides at the grain boundary; the borides are effective nucleation sites particularly since local Ti depletion can occur near the interface of the growing titanium borides during cooling. In the absence of B addition, the lamellar structure starts to form only at temperatures below T-0, suggesting that a large undercooling is required for the nucleation of lamellae even at the grain boundaries. On the other hand, the B addition greatly retards the kinetics of the alpha-to-alpha(2) ordering reaction by markedly increasing its critical cooling rate without a large change in the ordering temperature. This is believed to be due to its tendency to segregate strongly to the antiphase boundaries
Continuous cooling β-to-α transformation behaviors of extra-pure and commercially pure Ti
No full textThe in-situ continuous cooling beta-to-alpha transformation kinetics of extra-pure (EP) Ti and of grade-4 commercially pure (CP) Ti were investigated using a fully computer-controlled resistivity-temperature realtime measurement apparatus and transmission electron microscopy. The beta-to-alpha' martensitic transformation occurs under near pure shear condition, and the habit plane of lath-type martensite was determined to be (41 (5) over bar0)alpha' parallel to {43 (3) over bar}beta, which is in good agreement with the prediction of the crystallographic theory. The M-S temperature of EP-Ti was measured as 800degreesC and can be raised by up to about 40degreesC due to the generation of thermal stress and local deformation during rapid cooling. The massive transformation was, for the first time, observed to occur over a wide range of cooling rates in an EP-Ti. The massive start temperature and its occurrence were, unlike the martensitic transformation, hardly affected by the generation of thermal stress and local deformation during rapid cooling. The stable regime of massive transformation in a grade-4 CP-Ti was considerably shifted toward a slower cooling rate side and was significantly contracted at the same time. This is because the presence of iron impurity not only largely suppresses the massive transformation but also significantly delays a long-range diffusional transformation
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
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
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