1,721,234 research outputs found
The quest for a truly parsimonious airfoil parameterisation scheme
No full textThe conceptual phase of the aircraft design process demands a parsimonious description of the airframe geometry. While there is no hard and fast upper limit on the affordable number of variables, the so-called 'curse of dimensionality' must always be kept in mind: if a thorough, conceptual level search of a one-variable space can be accomplished by the evaluation of n candidate designs, the same level of thoroughness (however one chooses to define this) will demand nk evaluations in k-dimensional space. Therefore, to make the design search tractable and the complexity of the geometry definition at a level where the effect of the variables can be readily understood by the designer, the number of airframe definition variables should be minimized. This has an impact on all of the components, perhaps most importantly on airfoil-type section definitions that feature on all 'wing-like' surfaces. It is therefore imperative to define these sections as parsimoniously as possible. In this paper we examine a series of parameterization schemes, whose chief conception criterion was conciseness in terms of the number of design variables. Another constraint we are considering is the ease of implementation in a commercial off-the-shelf Computer Aided Design engine
Aerodynamic design optimization using flow feature parameterization
No full textDesign optimization methods using high-fidelity computational fluid dynamics simulations are becoming increasingly popular in the area of aerodynamic design, sustaining the desire to make these methods more computationally efficient. Such design strategies typically define the aerodynamic product using a
parametric model of the geometry, but this can often require a large number of design variables, increasing the computational cost. This thesis proposes that a parametric model of aerodynamic flow features, rather than geometry, can be a parsimonious method of representing designs, giving a reduction
in the number of design parameters required for optimization. The parameterization of flow features is coupled with inverse design, in order to recover the corresponding geometry. While an expensive analysis code is used in evaluating design performance, computational cost is reduced by using a low-fidelity code in the inverse design process. This newly presented method is demonstrated using four case studies in 2-D
airfoil design, in which the parameterized flow feature is the surface pressure distribution, and two case studies for 3-D wing design, in which the spanwise loading distribution is parameterized. These strategies are consistently compared against a benchmark design search method which uses a conventional parameterization of the geometry. The two methods are described in detail, and their relative performance
is analysed and discussed. The newly presented method is found to converge towards the optimum design significantly more quickly than the benchmark method, providing designs with greater performance for a given computational expense. A parameterization of flow features can generate designs with higher quality and detail than a geometry-based method of the same dimensionality
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
- …
