1,720,956 research outputs found
Multilevel modeling of solid oxide electrolysis
No full textThis chapter discusses the methods of numerical modeling of solid oxide electrochemical cells operated in electrolysis mode. Techniques related to computer simulations of processes taking place in a high-temperature electrolyzer at the level of microstructure, cells, stack, and power systems with solid oxide electrolyzers (SOEs) are presented. A brief introduction to the key electrochemical and mass and energy transfer processes is followed by a discussion of numerical approaches, with particular focus on reduced order and lumped volume models. Numerical methodologies related to system-level studies, including both steady state (i.e., nominal and off-design) and dynamic operation, are presented for the purpose of characterizing the thermodynamic performances. This chapter presents recent advances in the numerical modeling of SOEs and provides a review of recent literature in the field
Numerical model of planar anode supported solid oxide fuel cell fed with fuel containing H2S operated in direct internal reforming mode (DIR-SOFC)
No full textExperimental analysis of a planar 100 mm × 100 mm SOFC cell was conducted during operation at 1173 K in direct internal reforming (DIR) mode. In the first phase the rate of direct internal reforming was varied from 0 to 100% what corresponds to complete external reforming and complete DIR, respectively. In the second phase 1.2 ppm(v) of H2S was introduced to the feeding gas and the variation of the rate of direct internal reforming was repeated. Following the experimental analysis the numerical model was proposed to determine the correlation between the presence of the poisoning agent and the electrochemical performance. The effect on the resistance of the cell was studied. The lumped volume model was applied to predict the cell voltage. With the use of the experimental data it was possible to determine the relative change of the model parameters which describe the ionic and electronic conductivity of the SOFC. Model was adopted for predictive modeling of the solid oxide fuel cell, operated in DIR-SOFC mode with and without the presence of hydrogen sulfide. Additionally, literature data measured for a cell operated in complete internal reforming mode with variation of the sulfur content in the feeding gas were analyzed to define the effect of H2S content on the performance drop. Relative change of the resistance of a cell was correlated with the rate of internal reforming and the content of sulfur.
Results of the analysis show that the degradation of the performance of SOFC due to sulfur poisoning during operation in DIR mode can be modelled with high fidelity. Change of the ionic and electronic resistance of a cell accounted for the maximum of 34 and 53%, respectively when the rate of DIR was altered between 0 and 100%. The contribution of the sulfur poisoning accounts for 69 and 79% when the H2S content varies in the range of 0.001–5 ppm(v). With average relative prediction error below 3%, the proposed approach finds good application in simulating the performance of a cell exposed to different gas mixtures with different levels of sulfur in the fuel stream
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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