1,721,233 research outputs found
Packed and Monolithic Reactors for the Dry Reforming of Methane: Ni Supported on γ-Al2O3 Promoted by Ru
No full textThe CO2 reforming of CH4 or dry reforming (DRM) is as an efficient way for the CH4 and CO2 valorisation.
The DRM plays also an important role on the electrochemical performances and the long-term stability of solid oxide fuel cells (SOFCs) fed by CH4 or biogas.
Nickel is so far the most active catalyst for the DRM, but also highly prone to carbon formation, because, together with the ability to activate the C-H bond, Ni has high affinity to carbon. The Ni particle size has a strong effect on the carbon tolerance of the catalyst, therefore, the stabilization of small Ni nanoparticles at high temperatures is a promising way for the lifetime increase [1, 2]. Another strategy is the addition of a second metal (i.e Ru, Pt, Cu, Co) resulting in the formation of less C-sensitive alloys or in the increase of Ni dispersion.
The development of structured and unstructured catalysts for DRM based on Ni nanoparticles (10 wt%) supported on γ-Al2O3 promoted by a small amount of Ru (0.05 wt%), has been investigated. Unstructured catalysts (packed powder) were prepared by wet impregnation method and a combination of wash coating-wet impregnation methods was used for structured catalysts (cordierite monoliths). Samples were characterized by XRD, BET, H2-TPR, TEM and FE-SEM techniques and the catalytic activity for DRM was studied at 800 °C during time on stream with a mixture of CH4:CO2:Ar=45:45:10 vol.% and a gas space hourly velocity GHSV=11400 h-1 (150 cm3 min-1)
Morphological analysis confirmed that a large amount of carbon filament was deposited on Ni catalyst mainly by a tip growth mechanism, whereas on Ni-Ru, few carbon filaments were deposited with a base growth mechanism mainly in the inlet region. Moreover, the comparison between structured and unstructured catalyst underlined the advantages of structured catalysts over conventional packed bed reactors such as: increased mass and heat transfer, lower pressure drop, larger surface to-volume ratio and compact reactor design
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
Intermediate temperature SOFC fed by biogas: external reformer development
No full textThis work is focused on the development of an external reformer of methane using Ni-based structured and unstructured catalysts. Nickel is so far the most active catalyst for the DRM, but also highly prone to carbon formation, because, together with the ability to activate the C-H bond, Ni has an high affinity to carbon. The Ni particle size has a strong effect on the carbon tolerance of the catalyst, therefore, the stabilization of small Ni nanoparticles at high temperatures is a promising way for the lifetime increase. The catalysts were prepared by wet impregnation of active phase (10wt.% Ni) on γ-Al2O3 or Ru(0.05 wt.%)/γ-Al2O3 and wash coating deposition of the carrier on cordierite monoliths. The samples were characterized by XRD, FE-SEM, H2-TPR, BET techniques and the catalytic activity for DRM was evaluated at 800°C during time on stream. Catalytic tests showed that Ni particles, obtained by reduction of Ni-α species, were active for the DRM reaction with low carbon formation, whereas catalysts with large amount of Ni-β deactivated rapidly during TOS without carbon formation
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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