1,720,967 research outputs found
Performance Optimization of a Heavy Class Helicopter Engine Installation Using Genetic Algorithms Coupled With CFD Simulations
Get PDFAerodynamic design and optimization of engine installation is a pivotal part of the helicopter design process. To this
purpose, an adaptive problem-independent and reliable optimization methodology would be particularly valuable for
accomplishment of such goal. The application of advanced evolutionary algorithms coupled with CFD solvers for
the accurate flow solution of validated numerical models represents a very powerful tool for the parametric design
and optimization of engine installation components. Within the JTI Clean Sky FP7 project “HeavyCopter” the
consortium constituted by the University of Padova (UNIPD) and the spin-off company HIT09 developed an
automatic optimization loop based on an in-house genetic algorithm called GeDEA, and applied it to engine
installation design of a heavy-class helicopter. This paper illustrates the application of the above mentioned
optimization loop both at cruise and hover reference flight conditions for such a helicopter. The algorithm pursues
the minimization of the total pressure losses at the air intakes while keeping the flow distortion at the engine inlet at
the lowest level; regarding the exhausts, the back-pressure is minimized in order to increase the power output of the
engine while preserving the entrainment ratio. The results highlight significantly improved performance margins
with respect to the baseline both for intakes and exhaust
A New Methodology for Determining the Optimal Rotational Speed of a Variable RPM Main Rotor/Turboshaft Engine System
Get PDFVariable speed rotors represent an innovative field of research for the development of new rotorcraft designs. The
problems related to employing a main rotor variable speed are numerous and require an interdisciplinary approach.
For this reason, a first effort has been made to understand the performance implications of coupling helicopter trim
and turboshaft engine simulations. Following this, two different models of a UH-60 Black Hawk helicopter and a
GE T700 turboshaft engine are implemented and validated against experimental data. Then, an optimization
algorithm is employed to find the optimal main rotor speed with the aim of minimizing fuel consumption. Different
simulation cases are analyzed to quantify the benefits related to the optimal main rotor speed depending on flight
condition, altitude and helicopter gross weight. It is found that coupling the helicopter and engine model is necessary
to adequately achieve the correct rotational speed corresponding to minimum fuel consumption. More than 10% fuel
saving is shown to be feasible. The results obtained by means of numerical simulations are widely discussed and
future possible applications of the methodology are suggested
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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