1,720,958 research outputs found
Process simulation and optimisation of H-2 production from ethanol steam reforming and its use in fuel cells. 1 : Thermodynamic and kinetic analysis
Full text linkEthanol was considered as raw material for hydrogen production by steam reforming. Reformate purification from CO to feed fuel cells may be accomplished by well established routes, such as high and low temperature water gas shift and methanation, to be integrated with the H2 production unit. A PEM fuel cell can be used for power cogeneration. Data and layout have been inspired by an existing unit Helbio, GH2-BE-5000, capable of delivering 5 kWelectrical + 5 kWthermal output. In order to size and simulate the steam reforming reactor, reliable and complete kinetic data are needed. Partial information has been only found in the literature, in spite of well detailed analysis of the reaction mechanism. In the first part of this work, alternative reaction networks and kinetic models are critically reviewed and compared. Reliable and complete models were applied to literature data to estimate sound kinetic parameters for reactor modeling and simulation, objective of the second part of this work. At first, the equilibrium composition of a reacting mixture was calculated as a function of temperature, pressure and water/ethanol ratio, to define the boundary conditions of this investigation. Then, after selection of three alternative models to represent the complex reaction scheme of bioethanol steam reforming, a full set of kinetic parameters has been estimated and checked for consistency. The latter has been successfully applied to reformer sizing and simulation, as fully described in part 2
Process simulation and optimization of H-2 production from ethanol steam reforming and its use in fuel cells. 2 : Process analysis and optimization
Full text linkThe feasibility of power cogeneration through fuel cells using bioethanol with different concentration has been considered. Data and layout have been inspired by an existing unit Helbio, GH2-BE-5000 (5 kW(electrical) + 5 kW(thermal)) system for combined heat and power generation (CHP). The system is constituted by six reactors connected in series for hydrogen production and purification and by a fuel cell of the mentioned capacity.
To evaluate process efficiency and the possibility to operate with diluted bioethanol feed, characterized by lower purification cost, different process layouts have been tested. Particular attention is paid to the intensification of the heat exchange network, to increase the overall plant efficiency. Heat supply to the steam reformer has been accomplished by burning part of the reformate, since diluted ethanol is not suitable to feed the burner as in the experimental process layout.
The water/ethanol feeding ratio has been taken as major parameter for simulation. An increase of this variable improved H-2 yield due to promotion of the water gas shift reaction and lower impact of the hydrogen-consuming methanation step. However, higher heat input was required by the reformer, implying the delivery of a higher fraction of the reformate to the burner instead than to the fuel cell. This means lower electric output and efficiency. However, the presence of a high enthalpy steam exhaust increased the available thermal output, with consequent increase of the thermal and overall efficiency of the plant
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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