1,721,146 research outputs found
Linear reduced order modelling for gust response analysis using the DLR-TAU code
No full textA unified modelling approach, using computational fluid dynamics, to calculate the flutter stability and dynamic gust response of realistic aircraft models is outlined. The approach uses an eigenmode decomposition of the coupled problem combined with a (linear or nonlinear) Taylor expansion of the nonlinear, full order residual function. The necessary information for the flutter stability analysis, aerodynamic influence coefficients, is readily calculated. The aerodynamic influence is presented in a form which is in line with industrial practice using corrected doublet lattice method aerodynamics. Based on the stability analysis, eigenmodes are used to produce a reduced model for the gust response analysis. With the projection of the full order system on the eigenmode basis, a small set of equations governing the dominant dynamics is found. The approach is general to work with a variety of numerical schemes for the different physics involved in the coupled problem. In addition, arbitrary parameter variations can be included in the reduced model. The methods are used herein for the computational fluid dynamics solver DLR–TAU, which is adopted by industry throughout Europe, for aerodynamics. Structures are described by the standard modal form of a finite–element model. While pre–computations to evaluate the reduced order model require heavy computational resources, the reduced model can be solved in a matter of seconds on a desktop machine. The test cases presented to demonstrate the modelling capability include a wing structure and a realistic passenger aircraf
Solution of linear systems in Fourier-based methods for aircraft applications
No full textComputational fluid dynamics Fourier-based methods have found increasing use for aircraft applications in the last decade. Two applications which benefit are aeroelastic stability analysis and flight dynamics for which previous work is reviewed here. The implicit solution of the methods considered in this work requires an effective preconditioner for solving the linear systems. New results are presented to understand the performance of an approach to accelerate the convergence of the linear solver. The computational performance of the resulting solver is considered for flutter and dynamic derivative calculations
Gust Analysis using Computational Fluid Dynamics Derived Reduced Order Models
Full text linkTime domain gust response analysis based on large order nonlinear aeroelastic models is computationally expensive. An approach to the reduction of nonlinear models for gust response prediction is presented in this paper. The method uses information on the eigenspectrum of the coupled system Jacobian matrix and projects the full order model, through a series expansion, onto a small basis of eigenvectors which is capable of representing the full order model dynamics. The novelty in the paper concerns the representation of the gust term in the reduced model in a manner consistent with standard synthetic gust definitions, allowing a systematic investigation of the influence of a large number of gust shapes without regenerating the reduced model. Results are presented for the Goland wing/store configuration
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
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