1,720,957 research outputs found
Some Results on Joint Iterative Channel Equalization and Turbo Decoding for OFDM Systems
No full textThe use of turbo/LDPC channel coding in wireless communication systems opens new avenues as far as the optimization of other signal detection functions are concerned. For instance, channel estimation/equalization may greatly benefit by the presence of high-efficiency channel coding with iterative decoding. In this paper we assume multicarrier (OFDM) transmission on a (time-invariant) frequency-selective wireless channel, and we show how to integrate soft-output iterative detection with (iterative) channel estimation. The conventional approach to channel estimation relies on pilot symbols suitably inserted in the data frame. We show here how to use the soft outputs produced by the iterative decoder at each iteration to "supplement" the pilot symbols and aid the function of channel estimation and equalization
A Novel Carrier Recovery Technique for Filter Bank Multicarrier Wireless Systems
No full textFilter bank (FB) multicarrier modulation exhibits several properties which make it an attractive approach not only for high speed copper wire communications networks but also for broadband wireless applications. In this paper, we derive a nondata aided carrier frequency offset recovery algorithm for wireless FB-based systems. The estimator is based on a maximum likelihood approach and has a feedback loop structure. A number of proper simplifications make the problem tractable and allow to reduce the computational complexity. The algorithm accuracy is examined by computer simulation for AWGN and frequency selective multipath channel showing an considerable robustness against timing errors
“Un approccio object-oriented per la perimetrazione di aree percorse da incendio mediante immagini VHR Quickbird”
No full text“La perimetrazione di aree percorse da incendio mediante elaborazione di immagini satellitare ad elevatissima risoluzione”
No full text"Unsupervised segmentation algorithm based on Markov Random Fields applied to high resolution satellite images"
No full text
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
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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