1,721,113 research outputs found
7th international ERCOFTAC symposium on Engineering Turbulence Modelling and Measurements (ETMM7) Limassol, Chypre, June 4-6, 2008,
No full textOrganizing Committee: LESCHZINER M.A. (Chairman), KASSINOS S. (Co-chairman and local organiser), BONNET SJ.P., LAURENCE D., MENTER F., RODI W., TOMBOULIDES A., TROPEA C
Turbulent Flow Over Two-Dimensional, Surface-Mounted Obstacles:Plane an Axisymmetric Geometries
No full textMeasurement and prediction of the Gaussian beam effect in the phase Doppler technique
No full textUnder certain circumstances, particle size measurements using a phase Doppler instrument can be erroneous due to the Gaussian beam effect, sometimes referred to as the trajectory effect. This is especially true under extenuating circumstances such as when, for cost reasons, only two detectors are being used, when the choice of detector off-axis and/or elevation angle is limited through the application, when the signal processing has only limited validation possibilities or if a particularly small measurement volume must be employed. All of these factors may be disadvantageous for measuring larger particles.
In this study the physical origins of the Gaussian beam effect are examined anew. The interpretation is based on determining for each light scattering order the position of the detection volume and their separation distances from each other. Using this information and the analysis of so-called dual-burst signals, a method of estimating the maximum allowable particle size to avoid such effects is proposed. This estimation should aid users in evaluating or configuring their system for a particular application.
In this method a tolerance limit is prescribed, under which the measured phase difference can vary due to unwanted scattering orders. For variations exceeding this limit, the respective particle size is considered to be too large to be reliably measured using the specified detection positions (symmetric detectors in elevation angle). These results, and also the shift of the detection volume position based on a geometrical optics analysis, have been experimentally verified. The Gaussian beam effect has been systematically demonstrated in the experiment using a stream of monodispersed droplets traversed through the measurement volume
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
Time evolution of liquid drop impact onto solid, dry surfaces
No full textThe normal impact of liquid drops onto solid, dry surfaces has been studied experimentally, using high-resolution digital photography. A large number of parameters were varied in a systematic manner. The focus of this paper is the quantitative determination of the influence of these parameters on the drop spreading upon impact and on the phenomenological description of the outcomes. Dimensional similarity of the spreading can only be achieved for the very early stage of the impact process. At later stages, the number of influencing factors increases, generally precluding any universal correlation. Particular emphasis is placed on the influence of the wettability and the surface roughness on spreading.</p
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
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