1,721,005 research outputs found
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
Built-up terrain wave propagation by Fourier split-step parabolic wave equation-ray optical techniques
No full text8 S.Fourier split-step (FSS) solutions of the parabolic wave equation (PWE) represent wave fields in terms of plane wave decompositions. However, those field solutions are usually only valid in the air space above built-up terrain, whereas field predictions for modern wireless systems often require knowledge of the fields on a street level. Since FSS PWE solutions with large step sizes are not applicable for field computations between irregular scattering obstacles such as buildings, this problem is overcome by a two-step approach combining the FSS solution of the PWE with ray optical techniques to compute the fields at ground level in wooded and urbanized areas. To account for the great variety of propagation effects in a statistical sense, direct rays, reflected rays, diffracted rays and attenuated rays at typical receiver locations are included into the considerations. Comparisons to a wide variety of measured data show that this two-step approach produces better results than state of the art semiempirical field prediction techniques.38Nr.
A Multilevel Fast Multipole Method with Spherical Harmonics Expansion of the k-Space Integrals
No full textAdvances in semi-empirical terrestrial wave propagation modeling for macrocellular environments
No full textS.907-910In this work, we concentrate on semi-empirical wave propagation modeling for macrocellular environments where the transmitter antenna is located quite above any surrounding buildings or vegetation. Also. focus on two-dimensional propagation along the great circle path between transmitter and receiver positions. Such methods are useful in flat and moderately undulating terrain as found in most inhabited areas
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
Modelling of integrated antenna - scatterer configurations by hybrid finite element - boundary integral - multilevel fast multipole methods
No full textS.1
Iterative near-zone preconditioning of iterative method of moments electric field integral equation solutions
No full textS.101-102A preconditioning operator for the iterative solution of the electric field integral equation as applied to metallic scattering objects is iteratively computed employing the generalized minimal residual algorithm (GMRES). Using the strongest method of moments matrix elements only (typically in the near zone), iteration of the sparse preconditioner converges very quickly. In contrast to direct factorization of the near-zone matrix, no matrix fill-ins need to be handled. Excellent convergence of the preconditioned system using GMRES again is demonstrated by scattering computations for a rectangular metallic plate and a metallic cube.
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
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