1,721,024 research outputs found
Main Effects of Intercooling and Regeneration on Aeronautical Gas Turbine Engines
No full textThe reduction of fuel consumption in aircraft engines, together with the achievement of high performance levels, is always one of the main aim of the designers. Along with these needs another engine characteristic has become of primary importance: the emission reduction. To achieve these goals it does not seem suitable to improve the technology maintaining the scheme of actual engines. Some new features need to be introduced in the engines. Regeneration and intercooling seem to be most promising in this sense. The aero ngines that seem more suitable for the introduction of these practices are turboprop and high by pass ratio turbofan. This work presents the results of a study about the effects of the introduction of regeneration and intercooling on fuel consumption and performances of turboprop and turbofan engines. The study has been done by the development of a thermodynamic numerical code, allowing the simulation of the working thermal cycle of the two engines at different engine and operating conditions. Copyright © 2010 by. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission
Analysis of The Subdivision of the Enthalpy Drop in a Turboprop Engine with Regeneration
No full text
REGENERATION AND INTERCOOLING IN GAS TURBINE ENGINES FOR PROPULSION SYSTEMS
No full textThe needto reduce fuel consumption in modern gas turbine engines is evident, and with today's oil price levels it has become of primary importance. Infact oil price, and consequently aircraft fuel consumption, is one of the most important economic element in airlines management. Regeneration and intercooling are two of the most effective practices used in ground based power plants to achieve yhese goals. However they are not still used in gas turbine engine for propulsion systems mainly for the extra weight and size due to the presence of the heat exchangers and for the more complicated flow pattern that it comes from it. If we will be able in the near future to overcome these technical problems we can think that the same benefits obtained for the ground based plants could be transferred to propulsion systems. In particular turboprop engine seems to be the most suited to this purpose thanks to its smaller mass flow rate and its gas path. A thermodynamic cycle analysis is performed to put in evidence the advantages, in terms of power increase and fuel consumption reduction, of the introduction of regeneration and intercooling in a turboprop engine
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
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