1,720,969 research outputs found
Beamforming in highly reverberant wind tunnels possibilities and limitations
No full textClosed-section hard-walled wind tunnels are routinely used for aerodynamic testing during the early stages of vehicle design. The use of microphone arrays and beamforming processing in such environments can yield useful source localisation information; yet there are concerns as to the consistency of quantitative results from such methods when compared to anechoic openjet tunnel testing. Higher background noise levels, microphones in contact with the turbulent boundary layer, and the highly reverberant nature of the measuring environment are of particular concern. In this paper we show that accurate results in closed-section wind tunnels are still possible using the cross-spectral matrix diagonal removal (DR) technique, and with dereverberation. With DR, improvements in beamformer’s accuracy up to 10 dB can be achieved when compared to standard beamforming. De-reverberation gives an additional 10 dB improvement, and provided that the noise contamination to the microphone pressure data is somewhat suppressed, errors within §1dB can be expected. Both of these methods do not require any
additional changes to the physical infrastructure of the measuring environment
Towards more accurate beamforming levels in closed-section wind tunnels via de-reverberation
No full textThe ability to perform aeroacoustic measurements in closed-section wind tunnels is important in vehicle design, but presents significant problems compared with anechoic open-jet tunnel testing. The use of microphone arrays and beamforming processing can yield useful source localisation information, but there are concerns as to the consistency of quantitative results from such methods. In this paper some of the deficiencies of current beamforming practice are highlighted; in particular, inaccuracies in levels arising from the
reverberant sound field in hard-walled wind tunnels. Notably, the use of free-space Green's functions when beamforming in such conditions is shown to be a significant source of errror, and an image source method is proposed to improve accuracy by de-reverberating the
measuring environment. Comparisons are made between the conventional and proposed approaches using microphone array measurements of a compact source in a closed section wind tunnel. Results show that the new de-reverberation method can give improvements in accuracy even if the wind tunnel geometry is not modelled accurately, provided that the number of image sources is chosen correctly. The results also highlight the significant challenges associated with Green's functions measurements in highly-reverberant environments
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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