1,721,029 research outputs found
Invariant geometric properties of a class of 3D chaotic flows
No full textThis article extends the analysis developed by Giona and Adrover [M. Giona, A. Adrover, Phys. Rev. Lett. 81 (1998) 3864] for 2D area-preserving diffeomorphisms to 3D volume-preserving C-infinity-diffeomorphisms of the 3D torus topologically conjugate to a linear map. The article analyzes the invariant geometric properties of vector dynamics and surface element evolution in 3D systems and provides an analytic expression for the probability measure describing pointwise statistical properties of the unstable foliations in the hyperbolic case. The convergence propel ties of this measure are addressed starting from the dynamics of surface elements. The application of the methods developed to physically realizable 3D chaotic flows such as ABC flow is discussed in detail. (C) 2000 Elsevier Science B.V. All rights reserved
The application of diffusional techniques in time-series analysis to identify complex fluid dynamic regimes
No full textDiffusional Analysis of Intermittent Two-Phase Flow Transitions
No full textDiffusional analysis is employed to characterize two-phase flow regime transitions in horizontal pipes. The scaling analysis of the mean square displacement R(z)(2)(n) associated with the diffusional process driven by density fluctuations proves to be an efficient method for two-phase regime identification. Intermittent flow regime transitions are discussed and compared with theoretical and semiempirical models
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
Characterization of subregimes in two-phase slug flow
No full textA new subdivision of the slug flow region, determined on the basis of different how features, is presented. The characteristic features of each subregime have been shown by diffusional analysis of experimental time series relative to intermittent flow. It is found that, at low values of the mixture velocity, V-m = j(L) + j(G), a subregime (elongated bubble with dispersed bubble, EDB) with structural characteristics different from those usually attributed to slug flow (slug, SL) exists. It is demonstrated that the application of slug flow models to the whole slug flow region may lead to errors in the estimation of flow parameters, especially in large-diameter pipes (industrial application). A modification of the existing models for the flow variables (slug translational velocity, slug length and slug void fraction) is proposed in the light of the results obtained and confirmed against present and existing data
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
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