1,720,954 research outputs found
Low CO2 emissions chemically recuperated gas turbines fed by renewable methanol
Full text linkSteam reforming of the fuel in chemically recuperated gas turbine (CRGT) plants allows performing a heat recovery of the gas turbine exhausts, boosting the plant performance. Power-to-liquids technologies are a very interesting solution for storing the excess of renewable electricity into liquid fuels. Among the renewable fuels, methanol is well-known as a hydrogen carrier and an energy feedstock. Indeed, methanol can be stored, transported, and used in an easier way than hydrogen.
In this paper a CRGT fed by renewable methanol produced in power-to-liquids plant through the CO2 hydrogenation process was studied. The hydrogen needed to synthesize methanol is produced in an alkaline electrolyser, while the CO2 is captured from the CRGT exhausts. The opportunity of introducing an organic Rankine cycle (ORC) to enhance the energy production was also investigated. Dedicated simulation models of the single sections and of the overall system were developed through the commercial software Aspen Plus.
The overall system was sized to generate about 350 kg/h of methanol, resulting in a power production in the order of 600–750 kW. The study demonstrated that the integrated system based on a CRGT plant fed by renewable methanol can effectively store RES surplus and produce electricity with very low CO2 emissions. The overall system shows a power-to-power efficiency of about 0.23 that can be slightly increased with the introduction of an ORC system to better exploit the heat released by the CRGT
Performance evaluation of an integrated energy system for the production and use of renewable methanol via water electrolysis and CO2 hydrogenation
Full text linkAiming at the decarbonization of society, power-to-liquids processes can favour the exploitation of the excess of renewable energy, producing methanol or other chemicals (such as dimethyl ether) by reacting electrolytic hydrogen and recycled CO2 (captured from industrial and power plants or directly from air). Such a system could behave as: - an energy storage system, storing excess renewable energy as chemical energy in liquid fuels and converting it into electricity during lack of renewable energy, - a source of fuels and chemicals for a variety of applications in many industrial sectors. This work concerns the conceptual design and performance analysis of a small-scale integrated energy system for the production and use of methanol from renewable hydrogen and captured CO2. The main components of the system are: - a reversible high temperature and high efficiency solid oxide cell (RSOC) that can operate in charge (electrolyser, SOEC) and discharge (fuel cell, SOFC) mode to store and use electricity using methanol as energy storage medium, - a catalytic reactor for methanol synthesis via CO2 hydrogenation. A thermal energy storage (TES) system based on a phase change material (PCM) is also included. To predict performance of the main components and of the overall system, numerical simulation models were developed. Performance and efficiencies of each system component and of the overall system were evaluated through extensive mass and energy balances, considering two different configurations with and without TES integration. Performance indexes were calculated to analyse the goodness of introducing a TES. The global efficiency of the overall system increases from 30% to 35% when heat is recovered between sections via the TES system
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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