1,720,992 research outputs found
Mechanisms of high pressure hydrogen environment embrittlement in austenitic stainless steels under tensile and fatigue loading
No full textHydrogen is known to degrade the mechanical performance of many engineering materials. The effects of its entry into metal matrices from manufacturing processes and service environments has been reported previously to result in loss of ductility and fracture toughness as well as increased fatigue crack propagation rates. One of these damage mechanisms, hydrogen environment embrittlement, was explored in stainless steels in order to provide better understanding of the role of the composition and microstructure in susceptibility to the effects of high-pressure hydrogen atmosphere on tensile and fatigue performance.Current knowledge in the field has been extended by investigating the influence of a high pressure hydrogen environment on monotonic tensile failure and fatigue crack propagation processes in the austenitic stainless steels, 304L and 316L, and to explore the effects of secondary variables on damage severity (temperature, pressure, frequency). Assessment of the role of microstructure and composition on susceptibility to damage was completed by comparison of alloys’ relative performance and their fracture characteristics by conducting tensile and fatigue testing in high pressure hydrogen environment at pressures ranging from 200 to 1000 bar and temperatures between -50 and +50?C. Fatigue testing work at high pressure (above 450 bar) and in the low temperature regime was completed using equipment designed as a part of the EngD project.Testing under high pressure hydrogen environment resulted in pronounced loss in ductility and increase in fatigue crack propagation rates in both materials, 304L steel was more adversely affected in all testing conditions than 316L. The degree of damage was observed to increase with increasing hydrogen pressure and reducing temperature in both load regimes. Increased testing temperature resulted in partial recovery of global ductility measurements in tensile tests while fatigue crack propagation rates were still significantly increased.The embrittlement mechanisms differed between 304L and 316L steels due to the different phase stability and deformation mechanisms characterising these alloys. In 304L, hydrogen was seen to facilitate crack propagation along microstructural features such as slip bands, phase and twin boundaries, with some indication of the effects of localised plasticity. While some of these mechanisms were observed to be operative in 316L, it was difficult to attribute the fracture of this steel to a particular mechanism. It appears that martensite formation and planar slip processes were not the only necessary conditions for hydrogen embrittlement. Features of interfacial fracture were noted in this steel, particularly at ferrite stringers and austenite matrix, possibly indicating fracture due to local accumulation of hydrogen and consequent ferrite embrittlement and localised fracture
Tessellation-Filtering ReLU Neural Networks
No full textWe identify tessellation-filtering ReLU neural networks that, when composed with another ReLU
network, keep its non-redundant tessellation unchanged or reduce it. The additional network complexity modifies the shape of the decision surface without increasing the number of linear regions. We provide a mathematical understanding of the related additional expressiveness by means of a novel measure of shape complexity by counting deviations from convexity which results in a Boolean algebraic characterization of this special class. A local representation theorem gives rise to novel approaches for pruning and decision surface analysis
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
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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