1,720,955 research outputs found
Experimental Activity on High Temperature PEM Fuel Cells
No full textEnergy systems based on fuel cells technology have received increasing attention because, by
providing both useful electricity and heat with high efficiency, even at partial loads, can have a
strategic role in reduction of greenhouse gas emissions.
The high power density, low operating temperature (<100 °C) and rapid start up of a proton exchange
membrane fuel cell (PEMFC) make it an emerging alternative to the combustion-based systems for
uses in transportation and stationary power generation (residential/commercial).
However, the technical issues linked to the syngas feeding (the CO poisoning on the anode catalyst)
and the need to assure a high proton conductivity in the whole operating range (heat and water
management to avoid the membrane “dry-out” and the cathode flooding), have addressed the
research to develop high temperature polymeric membranes which work at temperatures between
120° and 180°C, able to overcome these constraints.
In this paper experimental tests carried out on two different commercial MEAs in order to define the
most suitable for a laboratory stack, are presented and discussed. The first MEA (MEA1) is based on
PBI polymer doped with H3PO4, while the second one (MEA2) uses H3PO4–doped pyridine-based
polymer as electrolyte.
In particular the experimental activity has been addressed to the impact on cell performance of some
working parameters such as the operating temperature, the CO content in the anode gas feeding and
the air stoichiometry in the whole operating range.
Results have pointed out that the performance of MEA1 are better than those of MEA2 by varying
both the operating temperature and the anode gas composition, even if these differences are less
significant as the working temperature is lower than 140°C.
With referring to the air stoichiometry variation, its impact on MEA2 performance is more important in
comparison with that on MEA1. In fact, it is found that the polarization curve of MEA2 obtained for an
air stoichiometry equal to 3 is overlapped to that of MEA1 measured for an air stoichiometry of 2
Conventional and advanced biomass gasification power plants designed for cogeneration purpose
No full textAbstractIn this paper conventional and advanced biomass gasification power plants designed for small cogeneration application are defined. The CHP plants consist of a gasification unit, that employs a downdraft gasifier, and a power unit based on a microturbine in the case of conventional configuration, and on a solid oxide fuel cell module, in the case of advanced configuration. The plants are sized to supply about 100kW of electrical power.In order to investigate and to analyze the performances of the two plant configurations, in terms of thermal and electrical efficiencies, numerical models have been developed by using thermochemical and thermodynamic codes
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
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