1,721,051 research outputs found
Numerical Analysis and Design of New Exhaust Section Downstream of Constant Volume Combustor
Full text linkPressure Gain Combustors (PGC) exploit either their isochoric or detonative combustion increasing the theoretical thermal efficiency of a Gas Turbine cycle. On this basis, a Constant Volume Combustor (CVC) is developed operating with rotary valves while the chamber is fed with mixture of air and liquid isooctane. The present work describes the numerical design of a new exhaust section after the CVC. First, the design parametrization of the transition duct and the resulting Design of Experiments (DOE) of 81 samples are introduced. Every case is numerically tested and the election of the best sample is based on the pressure losses and the oscillations characterization. In the last part, the LS89 VKI vane is added at the aft part of the best transition duct
and the ensemble exhaust system is analysed with the help of transient CFD analysis. Every component is evaluated in terms of pressure losses and oscillations, while the operation of the vane is investigated in details. The results of the stator performance are discussed and compared with steady experimental data. During a CVC period, the cycle average outlet flow angle remains close to the outlet metal angle denoting promising results for the future numerical analysis of the subsequent rotor
Experimental Inert Characterization of an Exhaust System Downstream of a CVC
Full text linkNowadays, multiple research institutes focus their interest on the Pressure Gain Combustion Cycles (PGC) due to their superior theoretical performance compared to the traditional Joule cycle. On the contrary of the quasi isobaric conventional burners, a PGC cycle achieves increment of total pressure during the combustion process by utilizing either the detonation mode or the deflagrative isochoric combustion. As a result, PGC integrated in a Gas Turbine cycle can offer larger inlet stagnation pressure and temperature for the work extraction by the subsequent turbine module significantly elevating the theoretical cycle efficiency. Under this context, a prototype Constant Volume Combustor (CVC) has been developed operating with a mixture of liquid iso octane and air. With the help of inlet outlet rotary valves and a spark plug ignitor, sequential isochoric combustion events are accomplished. The current work aims at experimentally investigating the peculiar outflow of this combustor. CFD optimization techniques provided a transition duct that can be mounted downstream of the CVC to integrate it with a High Pressure Turbine (HPT) stage. The profile of the transition duct was designed and manufactured to serve the demands of the experimental test rig. The outlet of this component is followed by a converging diverging circular nozzle. On the top and lateral side of the transition duct are inserted windows to allow for penetration of a laser sheet and the visual inspection of the transition duct. Particles of silicon oil are seeded upstream of the CVC chamber. Hence, PIV analysis is conducted in the exhaust part. In addition, pressure sensors monitor the evolution of the pressure in the chamber, the inlet and the outlet of the transition duct. This experimental campaign is considered inert as no injection or ignition is performed inside of chamber. The valve motion provide strong pressure fluctuation to the outtake system. The transition duct outlet is able to alleviate any vertical distortion in the velocity profile which is imposed by the exhaust valves. As a result, a smooth acceleration is achieved for every moment of the cycle. These results are promising for the integration of this peculiar PGC with a subsequent turbine, as the benefits of the CVC operation will not be deteriorated by excessive pulsating outflow towards the HPT
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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