1,720,964 research outputs found
On Traffic-demand Based Multi-Beam BandwidthAllocation in Future Satellite Networks Using Beam-Hopping Techniques.
No full text.In this paper we consider adavanced multi-beam satellite communications at the Ka band in GEO satellite systems. In such a scenario an optimum utilization of the limited resources of the network can be achieved by means of beam-hopping techniques, which consist of the selection of a few beams on the overall coverage at each time-slot for transmission, on the basis of the spatial demands for the satellite services. This set of illuminated beams changes on a slot-by-slot basis over the duration of a periodically repeating window. This paper is a preliminary investigation of the implications, trade-offs, and system parameters involved in this new approach, associated with non-uniform bandwidth allocation to the satellite beams. Our target is to match as closely as possible the offered capacity to the traffic demand throughout the satellite coverage region. Since a combined optimization will result in an NP-complete problem, we fix some parameters (e.g. the maximum number of simultaneously illuminated beams in a time-slot) and investigate beam-hopping techniques which consist of a heuristic iterative process. The performance is assessed by means of simulations. We show that beam-hopping techniques, coupled with non-uniform bandwidth and power allocation, are good candidate to enhance mthe performance of the system in terms of bandwidth efficiency and utilization of the limited system resources
Repetitive manual operations in the dairy Sector: analyses and criteria for intervention
No full textEvaluation of temporal variations in moisture and calorific value of vine and olive pruning
No full textJointly Optimal Routing and Resource Allocation in Hybrid Satellite/Terrestrial Networks
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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
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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