1,720,970 research outputs found
Biofuels as opportunity for MCFC niche market application
No full textThe aim of the study is to compare three different cogeneration systems, internal combustion engine, gas turbine and molten carbonate fuel cell (MCFC), combined with an anaerobic digester plant implementing a technical–economical analysis and a multicriteria analysis. Through the analysis it is possible to show the validity of integrating a MCFC in combined heat and power configuration with anaerobic digester gas, a renewable source of energy, by-product of the treatment of wastewater, animal manure and organic solid waste. Even if fuel cell systems diffusion is still limited by high manufacturing costs, about 4500 h/kW, and is in need of reliable technology, the possibility of integrating renewable fuels, like biogas, with MCFCs can be a good niche market for fuel cell power plants and could promote their large-scale commercialisation. Through the analysis it is possible to show that with a cost of 3000 h/kW the MCFC is already competitive with other cogeneration systems
Experimental and theoretical analysis of H2S effects on MCFCs
No full textOne important advantage of MCFCs is the possibility of using different fuel gases (natural gas, coal gas, biogas, landfill gas, etc.). However, these fuels contain impurities that can damage MCFCs, and, of these, sulphur compounds seem to be the most harmful, even at low concentrations. The aim of this work is to test the effect of different H2S compositions on operating variables, investigate the relationships, propose phenomena reading and obtain new information to define tolerance limits. In particular, chemical, electrochemical and physical poisoning mechanisms were taken into account, trying to evaluate their importance studying the effects of exposure time, temperature and current density on MCFC performance when H2S polluted anodic gas is fed. To support the investigation, experimental tests were performed at the Fuel Cell Research Center laboratories of KIST (South Korea) and a theoretical analysis was also proposed to suggest operating strategies, for example showing how high current density or temperature values can emphasize the negative effect of poisoning. The results obtained gave new suggestions for approaching data interpretation, confirming the possibility of using MCFCs when a number of ppm of H2S is present in the feeding fuel
SULFUR POISONING IN MOLTEN CARBONATE FUEL CELL FED WITH BIOGAS
No full textAlternative energy sources have to be considered to overcome problems such as energy security and climate change associated with fossil fuel. Biomass is one of the most interesting alternative sources because is renewable, sustainable and widely available. Also biomass which is carbon-based differs from the other renewable energy sources because of their utilization for the energy carrier supply obtained by biological or thermochemical process. Biofuels need high efficient energy conversion technologies such as fuel cells because of their low energy content. Fuel cells are clean, efficient and silent, but need pure hydrogen as fuel. High temperature fuel cells (HTFCs) are more suitable for application of biofuel because they can include an internal reforming which give them fuel flexibility and because their electrodes are more tolerance against fuel contaminants. The research is focussed on molten carbonate fuel cell (MCFC) because of its technology that is more advanced than Solid Oxide Fuel Cell (SOFC) and because of its soon appearing at the marketplace as a commercial product. The most suitable biofuel for MCFC is biogas because reformed methane and carbon monoxide are fuels and carbon dioxide is a diluent. Biogas impurities such as sulphur compounds, mercaptanes, siloxanes and halogenated hydrocarbons affect cell performances. Hydrogen sulphide, which is the most important biogas impurities, reacts either chemically or electrochemically with the electrolyte and the anode affecting the power density and lifetime of the cell [1-4]. The aim of this work is to study the mechanism and the kinetic of hydrogen sulphide poisoning to be able to select alternative anode materials with high sulphur tolerance and high regenerative capability
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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