1,720,976 research outputs found
Italian COSMO-SkyMed atlas: R-Index and the percentage of measurability of movement
No full textSAR (Synthetic Aperture Radar) satellite interferometry is a helpful remote sensing technique for large areas analyses and monitoring, especially where the study area is difficult to access for practical or for legal reasons. As a result, the use of these techniques has significantly increased over the past three decades. Among the available different satellite constellations displaying different spatial and temporal resolutions, COSMO-SkyMed of the Italian Space Agency (ASI) represents a cutting-edge reality. COSMO-SkyMed constellation, launched in 2007 by ASI, is a valuable Earth observation tool that provides all-weather, day-and-night imaging capabilities with high resolution and a short revisit time. In this study, we produced an atlas for the entire Italian peninsula using two parameters (R-Index and Percentage of measurability of movement), in order to evaluate the quality and a-priori applicability of satellite interferometry data collected by the COSMO-SkyMed constellation. The atlas was obtained by means of the implementation of different model builders in the GIS (Geographical Information Systems) environment, providing a semi-automatic way to generate the above-mentioned outputs. The R-Index describes the likelihood of detecting Permanent Scatterers in mountainous areas, while the Percentage of measurability of movement indicates the percentage of real motion that interferometry can detect at a certain point in the analyzed region. A high-detail Digital Terrain Model (DTM) has been used to identify the most suitable areas for satellite interferometry monitoring and studying. The results of our analysis showed that the R-Index and the Percentage of measurability of movement could be used to pre-evaluate the quality of satellite interferometry data collected by the COSMO-SkyMed constellation. This research has important implications for disaster response, environmental monitoring, and scientific research and is one of a few cases in the world in which a unified representation for an entire country is provided
On the extraction of the reservoirs’ waterline using polarimetric X-band SAR measurements: the case study of the San Giuliano reservoir, Italy
Full text linkAccording to the World Bank data catalogue, (Formula presented.) records of reservoirs and their associated dams are present summing up a capacity of (Formula presented.) km3 of water. They play a crucial role in providing potable and irrigation water and, therefore, it is of paramount interest to effectively monitor such critical infrastructures. An effective approach is based on satellite remote sensing and, in particular, on the Synthetic Aperture Radar (SAR). In this paper, we critically investigate the use of polarimetric SAR measurements for reservoirs’ waterline estimation. Measurements of the novel COSMO-SkyMed Second Generation (CSG) X-band quad-polarimetric SAR related to the San Giuliano reservoir, in the South of Italy, are used to carry out an electromagnetic analysis of the different polarimetric scattering returns. Experimental results show that the cross-polarized channel, as well as the inter-channel phase, are noisy and, therefore, uninformative when used to design coherent polarimetric waterline extraction methods. From an electromagnetic viewpoint, this is due to the peculiarities of the reservoirs that call for low surface roughness and negligible wave pattern that, at once, result in a joint combination of un-tilted Bragg scattering and specular reflection. This implies that a low co-polarized backscatter and a cross-polarized signal largely below the system noise floor are to be expected. As a consequence, waterline extraction approaches that do not exploit the inter-channel phase, the so-called incoherent approaches, are shown to outperform the coherent ones
Observing inland water bodies by means of X-band polarimetric SAR imagery from second generation COSMO-SkyMed constellation
No full textThis study aims at demonstrating the ability of full-polarimetric X-band synthetic arperture radar measurements provided by the COSMO-SkyMed second generation satellite constellation to extract the waterline of inland water bodies and to classify the land use/cover of the surroundings. The former task is undertaken using a state-of-the-art unsupervised method that exploits a global threshold constant false alarm rate method together with morphological filters and a Sobel edge detection algorithm; while the latter goal is pursued considering an unsupervised scattering-based approach the relies on the Wishart distribution and the eigendecomposition parameters of the coherency matrix.Experiments are carried out on satellite data set collected over the San Giuliano reservoir, in the South of Italy, where a full-polarimetric COSMO-SkyMed second generation image and a Sentinel-2 optical image are collected. Results show that the adopted methodologies allow effectively extracting the profile of the reservoir and providing classification outputs of the surroundings according to the dominant scattering mechanisms
Beyenchime-Salaatin (Russia), Bigach (Kazakhstan), Chiyli (Kazakhstan), Chukcha (Russia), Dhala (India), El’gygytgyn (Russia), Gusev (Russia), Jebel Waqf as Suwwan (Jordan), Jänisjärvi (Russia), Kaluga (Russia), Kamensk (Russia), Kara and Ust-Kara (Russia), Karakul (Tajikistan), Karla (Russia), Kursk (Russia), Logancha (Russia), Lonar (India), Macha (Russia), Mishina Gora (Russia), Popigai (Russia), Puchezh-Katunki (Russia), Ragozinka (Russia), Shunak (Kazakhstan), Sikhote Alin (Russia), Sobolev (Russia), Sterlitamak (Russia), Suavjärvi (Russia), Tabun-Khara-Obo (Mongolia), Wabar (Saudi Arabia, Xiuyan (China), Zhamanshin (Kazakhstan)
No full textGoing 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
Observing intertidal coastal areas using full-polarimetric C- and X-band synthetic aperture radar measurements
No full textThis study is to analyze the multi-polarization/multi-frequency backscattering from intertidal areas using polarimetric Synthetic Aperture Radar (SAR) imagery collected by the C-band Radarsat-2 (RS2) and the X-band Cosmo-SkyMed Second Generation (CSG) satellite missions
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
- …
