1,720,966 research outputs found
Using nonlinear optical networks for optimization: primer of the ant colony algorithm
No full textUsing nonlinear Erbium doped optical fiber network we have implemented an optimization algorithm for the famous problem of finding the shortest path on the map for the ant colony to travel to the foraging area
UV and IR light generation in silica-based optical fibre tapers
No full textOptical fibre lasers offer significant benefits in comparison to other laser sources, such as extremely low thermal lensing, extraordinary good beam quality and very high plug efficiency. Up to date only near-IR sources have been manufactured in silica in fiberized forms. The challenge is to develop new fiberized UV and IR sources in a silicate fibre host.Here we show that up- and down-conversion in tapers made from silicate optical fibres can efficiently be used to generated light both in the UV and in the mid-IR. Simulations show that efficiencies in excess of 50% can be potentially achieved for lengths of the order of tens of millimetres
Fiber non-Turing all-optical computer for solving complex decision problems
No full textWe demonstrate an all-optical computer that solves one of the most difficult complexity problems, the Hamiltonian challenge of finding if a map can be traveled in a way that each town is visited exactly once
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
Minimize quantum-defect heating in thulium-doped silica fiber amplifiers by tandem-pumping
No full textIn this paper, we propose a simple model to investigate the quantum defect between pump and signal photons in thulium-doped fiber amplifiers. The achievable quantum defects are limited by several factors, i.e., pump and signal wavelengths, fiber length, area ratio between inner cladding and core, and gain and absorption at signal and pump wavelengths, respectively. Through the proposed model, we find that the quantum defect can reach as low as 1%-level. We also find that the smaller area ratio between inner cladding and core, the lower quantum defect can be obtained. The ultimate pumping approach will be core pumping. This can be realized through tandem pumping the thulium-doped fiber by the other fiber source at shorter wavelength with high brightness. Finally, it is necessary to optimize the pump and signal wavelengths and match the fiber length to obtain the lowest quantum defect
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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