1,721,398 research outputs found
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
FDTD modelling of spatial soliton propagation
No full textThe finite difference time domain method is used as a tool to model non-linear optical devices. Following this approach, Maxwell's equations are directly integrated in the time domain, avoiding any mathematical approximation. As an example, spatial soliton propagation and interaction will be modelled by the FDTD technique. Some new results will be discussed, to highlight the envisaged breakthroughs allowed by the method
TBC and PML conditions for 2D and 3D BPM: a comparison
No full textAny implementation of the beam propagation method, when used to analyse open problems, requires a procedure allowing radiation to leave the computational window. In this paper we present the results of a case study on the effectiveness of the classical Hadley's Transparent Boundary Conditions (TBC) and the Perfectly Matched Layer (PML) to handle strong radiation at the boundaries. A polished fibre coupler will be studied both in 2D and in 3D configurations using, in the former case, a scalar method and, in the latter, a full vectorial approach. Numerical results show that simple TBC can be used in 2D simulations also when high radiation occurs but they easily fail in 3D structures. Therefore, in these cases, the more complicated PML conditions should be preferred
Nonlinear PML boundary conditions for nonparaxial BPM in chi((2)) materials
No full textNonlinear perfectly matched layer (NL-PML) boundary conditions for a nonparaxial finite-difference beam propagation method are developed and applied to the simulation of spatial solitary waves in periodically poled second-order nonlinear materials. Their overall better performance is verified comparing their effectiveness with that of linear PML and transparent boundary conditions
Tunable narrow band optical reflector based on indirectly coupled micro ring resonators
No full textThis paper presents a novel narrow band wavelength selective optical reflector implemented by indirectly coupling two micro ring resonators in silicon-on-insulator technology. The device is studied using an analytical model based on the transfer matrix method. With the proposed configuration, by electrically driving the integrated micro heaters, a single reflection wavelength with narrow bandwidth can be tuned. The experimental results show a good agreement with the model outcomes. The average measured reflectivity over a wavelength span of 37 nm is 0.55, with a peak of about 50 pm full-width-half-maximum, which corresponds to a quality factor of ∼30, 000. The proposed device can offer an alternative approach to realize compact reflective structures for single wavelength reflection operations in photonic integrated circuits
Efficient magnetron antenna source for FDTD simulations of microwave applicator devices
No full textThe magnetron tube is the source commonly used for power
applications of microwaves at 2.45GHz. An efficient finite
difference time domain model of a magnetron antenna, useful for
tuning by simulations the best possible matching conditions for a
microwave launcher, is presented
.: Exponential modelling of Ultrasound fetal growth and computer evaluation of significant parameters.
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