1,720,997 research outputs found
FDBAQ A NOVEL ENCODING SCHEME FOR SENTINEL-1
No full textModern operational and/or high resolution SAR satellite
missions impose stringent requirements on on-board data
compression such as a higher data reduction ratio, more
flexibility, and faster data throughput. A novel approach is
Flexible Dynamic Block Adaptive Quantization (FDBAQ).
This method outperforms currently used Block Adaptive
Quantization with respect to Signal-to-Noise-Ratio related
to the compression ratio. The FDBAQ method allows bit
rate programmability with non-integer rates. This allows the
SAR information throughput to be optimized for different
types of targets and down-link scenarios using a tradeoff
between thermal and quantization noise
GMES Sentinel-1 FDBAQ Performance Analysis
No full textModern operational and/or high resolution SAR
satellite missions impose stringent requirements on on-board
data compression such as a higher data reduction ratio, more
flexibility, and faster data throughput. A novel approach is
Flexible Dynamic Block Adaptive Quantization (FDBAQ). This
method outperforms currently used Block Adaptive
Quantization with respect to Signal-to-Noise-Ratio related to the
compression ratio. The FDBAQ method allows bit rate
programmability with non-integer rates. This allows the SAR
information throughput to be optimized for different types of
targets and down-link scenari
Sentinel-1 Flexible Dynamic Block Adaptive Quantizer
No full textThe variable bit rate coding scheme designed for Sentinel-1 and named Flexible Dynamic Block Adaptive Quantizer (FDBAQ) is presented in this paper. FDBAQ technique adapts the number of quantization bits ac-cording to a local estimate of the signal-to-noise ratio (SNR) at the receiver. Its performance is shown to be su-perior to the currently used BAQ compressor [1] in terms of SNR related to the compression rate.
An overview of the design optimization, of the on-board and on-ground operations and of the system perfor-mances is provided. Results of simulations have been based on a 16-bit mosaic of reflectivity in C-band based on ENVISAT Global Monitoring data [2]
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
Polarimetric Calibration Monitoring by Permanent Scatterers
No full textThe PS calibration combines external devices, like corner
reflectors, transponders and the stable targets to provide
continuous monitoring of the radiometric quality of a SAR
instrument. The aim is to provide, on the bases of image
blocks (say 10 x 10 km), the precise geolocation and the
polarimetric signature of each scatterer. The scheme thus
requires (1) the identification of the stable targets, and (2) the
characterization of their Polarimetric scattering matrix by
external references. In that way, it would be possible to
calibrate even a dual polarimetric system
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