1,720,967 research outputs found
Effects on performance, combustion and pollutants of water emulsified fuel in an aeroengine combustor
No full textThe present work provides an experimental investigation of the use of water emulsified fuels to control the combustion performance and reduce nitrogen oxides emissions into a Jet-A1 fueled gas turbine combustor. Experiments have been carried out using a test rig equipped with a 300-kW liquid-fueled swirling burner. Several fuel-to-air ratios have been tested in combination with various water concentrations. Measurements of exhaust emissions have been performed. Furthermore, high-speed cameras in visible and ultraviolet spectral ranges, have been used. The snapshot Proper Orthogonal Decomposition of the flame images of both broadband emission and hydroxyl radical chemiluminescence has allowed to detect the most relevant flame structures, in combination with the modal frequency spectra. Results figured out that, the addition of water in the fuels led to lower combustion temperature and consequently to lower thermal nitrogen oxides than the case of neat fuel. On the other hand, the thermal efficiency significantly dropped in presence of high-water content (5% H2O) and ultra-lean conditions, while it remained acceptable at 2.5% H2O and fuel rich conditions. Furthermore, under the near-lean blowout condition, the flame becomes very unstable and flame oscillations take place in the axial direction. This combines with the increase in the relative energy of the first Proper Orthogonal Decomposition modes. Finally, the phase space analysis of modes 1–2 of the hydroxyl radical chemiluminescence emission defined a criterion for the detection of the establishment of the flame instability, which corresponds to phase angles ranging between -π/6 and π/6
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
Effect of jet-A1 emulsified fuel on aero-engine performance and emissions
No full textDue to the stringent emission requirements for a more sustainable transport, the efforts of the scientific community have gone into research and development of eco-friendly fuels for aeroengines. Water emulsified fuels represents a promising solution. In this regard, the present work provides two main contributions. First, an experimental investigation of the effects of the addition of water into jet-A1 fuel has been carried out on a 300-kW liquid-fueled swirling combustor. Direct measurements of both exhaust temperature and pollutant emissions, defined the diagnostics setup. Several water concentrations have been tested at different fuel/air ratios and under lean conditions, and the impact of each fuel composition has been evaluated on emissions reduction and combustor efficiency. Results pointed out the nitrogen oxides (NOx) reduction in combination with the lowering of the exhaust gas temperature, which coupled with losses in the combustion and in the overall thermal efficiencies. Despite this, the energy losses became negligible when water content in Jet-A1 was limited to 2.5% by mass, which still ensured the benefit in terms of NOx reduction in the measure of about 11% at φ = 0.36 up to 27.4% at φ = 0.18. Further increase of the water content to 5% at fixed φ = 0.36, as well as going to a leaner condition (φ = 0.18) at fixed water content of 2.5%, strongly impacted on the thermal efficiency which reduced to about 25.4% and 41.2%, respectively. Based on the thermal efficiency losses estimated through experimental results, a gas path analysis was performed by implementing a gas turbine model. This allowed to predict the impact of the water addition into Jet-A1 on the performance of the military turbojet Rolls-Royce VIPER 632-43. Both sea level take-off and cruise flight conditions have been analyzed. Numerical predictions confirmed the experimental finding of the NOx reduction in proportion to the reduction of the peak combustion temperature. In addition, the turbojet engine model figured out an increase of the thrust specific fuel consumption (TSFC) of about 6.7% and 22% for 2.5% and 5% of water in Jet-A1 respectively during sea level take-off. Its value rose to 8.0% and 26.7%, respectively, when under cruise conditions. Water addition decreased the engine thrust in proportion to the percent increment of the TSFC
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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