1,720,976 research outputs found
Optimized joint bandwidth and playout control for streaming-traffic over wireless-channels
No full textto be published on Communication in Applied and Industrial Mathemathics
A Secrecy Constrained Power Allocation for MIMO Wire-Tap Channels
No full textSince a wireless transmission requires to access to a shared medium, the communication is susceptible to adversarial eavesdropping. This paper describes how eavesdropping can potentially be limited by resorting to waterfilling-like algorithms with additional constraints. A Gaussian wiretap channel (WTC) is considered in which a transmitter sends confidential messages to its reference receiver in the presence of a passive eavesdropper. We approach the problem from two different perspectives, focusing either on the rate of the main link or the secrecy level. Through numerical analysis, we show how the information-secrecy regions can be the means to evaluate the quality of the main link and the secrecy level, resulting from our algorithms application. Finally we analyze the case of interfering signals (induced by users sharing the same transmission resource) to show their effects on both information rate and secrecy, even in the case of an eavesdropper able to mitigate the interference
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
Physical-Layer Goodput Maximization for Power Line Communications
No full textIn this paper, we present a new solution to the well-known integer bit loading problem for Power Line Communication systems, that is able to jointly consider transmission rate and bit error rate (BER) as performance parameters. This goal is achieved by means of a Trellis Coded Modulation (TCM), by taking advantage of its appealing property to combine modulation and coding, so as to state the power allocation problem as an optimization in which both BER and rate are tied to the TCM optimal design. The need to compare such a scheme with others known in the Literature in terms of performances, led us to give a brief insight into the two standard approaches: Maximum Rate (MR) and Minimum BER (MB), which consider as objective functions only rate or BER, respectively. Numerical results are presented to stress how our solution improve system performances, both in ideal condition and with additional impairments such as crosstalk and impulsive noise. ©2009 IEEE
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
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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