1,721,116 research outputs found
High efficiency process for the production of pure oxygen based on the SOFC-SOEC technology
No full textThis paper presents a novel system for production of pure oxygen based on the integration of a solid oxide
fuel cell (SOFC) and a solid oxide electrolyzer (SOEC). In the proposed arrangement, the SOFC provides
electricity, heat and H2O in vapour phase to the SOEC which carries out the inverse reactions of the
SOFC, that is the separation of H2O into H2 (used as a fuel for the SOFC) and O2 (representing the yield
of the system). Simulations carried out in different operating conditions show that when the integrated
SOFC–SOEC device runs at low current densities (less than 1000Am−2), pure oxygen can be generated
with an electric consumption comparable to mid-size cryogenic air separation units, and significantly
lower than small scale systems based on the PSA technology
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
BREAKING 70% NET ELECTRIC COMBINED CYCLE EFFICIENCY WITH CMC GAS TURBINE BLADES
No full textThis work focuses on the optimal cycle design criteria for heavy duty gas turbines employing CMC blades. A combined cycle model with detailed description of the cooled gas turbine is used to determine the optimal Turbine Inlet Temperature and pressure ratio for two values of maximum allowed CMC wall temperatures (1300, 1500 degrees C). Results indicate that the maximum efficiency of the combined cycle is achieved with pressure ratio above 60, posing the need of adopting two shafts for the gas turbine and high temperature materials for the high-pressure compressor. Net electric efficiency above 70% (LHV basis) can be approached with CMC blade wall temperatures of 1300 degrees C (TIT = 2000 degrees C) and efficiency values approaching 72% with CMC blade wall temperatures of 1500 degrees C and TIT of 2200 degrees C. Compared to current H-class gas turbines, the simple cycle efficiency increases by about 10 percentage points (> 53% vs. 43% LHV basis) and the net specific work/net power output by 66%-110% depending on the pressure ratio and TIT. The most critical challenge to achieve such performance appears to be the temperature gradient across the blade wall and the temperature capability (maximum surface temperature and temperature gradient) of the blade coatings
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
La trasmissione dei testi latini del Medioevo – Mediaeval Latin Texts and their Transmission TE.TRA. I
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