1,720,967 research outputs found
Pressure-less joining materials for SiC-based components for light water reactors
Full text linkSilicon carbide fiber-reinforced composites (SiC/SiC) are leading candidates to replace zirconium-based alloys as cladding in light water reactors (LWR), owing to their exceptional oxidation resistance and mechanical performance under accident conditions. However, pressure-less joining methods compatible with the extreme chemical and thermal environment of LWRs remain a major technological hurdle. This work evaluates two promising joining materials—Mo-wrap (a MoSi₂/Si composite) and SAY (a silica–alumina–yttria glass-ceramic)—under simulated LWR conditions. Joining was performed using both conventional furnaces and laser-assisted techniques. Joint integrity and microstructure were assessed by SEM/EDS and X-ray computed tomography. Hydrothermal stability was evaluated in static and flowing-water (loop) autoclaves up to 30 days at 330 °C and 150–155 bar. Mo-wrap joints showed partial degradation due to silicon dissolution, while SAY joints retained good structural integrity in static tests but suffered phase-selective corrosion under flowing conditions, with keivite emerging as the most stable crystalline phase. Laser-processed amorphous SAY joints exhibited improved corrosion resistance, though still limited under prolonged exposure. These findings advance the understanding of joining performance in nuclear-relevant environments and support the development of accident-tolerant fuel cladding.</p
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
Harmonic analysis of corroding systems considering diffusion phenomena
No full textDue to the nonlinear nature of a corroding system, a sinusoidal potential distortion results in an ac current response, which contains higher harmonics. These harmonics can be measured and evaluated to obtain kinetic information, for example the corrosion rate and Tafel parameters. A model was developed for the case that the anodic reaction was charge transfer controlled and the cathodic reaction was under mixed control, i.e., both the charge-transfer and diffusion determine the reaction rate. This model was used to obtain the corrosion rate and Tafel parameters for the corrosion of mild steel in an aerated sodium sulfate solution.status: Publishe
A theoretical study of AC-induced corrosion considering diffusion phenomena
No full textThe effect of AC-induced voltages on corrosion systems was investigated. Two cases were distinguished: the anodic and cathodic reactions were under activation control, the anodic reaction was under activation control and the cathodic reaction was under mixed control. For the first case simple relations could be derived that relate the AC-induced voltage with the corrosion potential and corrosion rate. For the second case numerical analysis was necessary to obtain these relations. It was shown that the influence of the AC-induced voltages on the corrosion behaviour strongly depended on the Tafel parameters. As the cathodic reaction was under mixed control the increase of the corrosion rate was limited to the diffusion-limited current density. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.status: Publishe
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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