1,720,956 research outputs found
Early detection and in-depth analysis of deformation phenomena by radar interferometry
No full textAbstract
The spaceborne differential interferometric SAR (DInSAR) technique may play an important role in the measurement of land deformation phenomena, especially in urban, suburban and industrial areas. In order to fully exploit its capabilities and increase its operational use, this paper proposes two complementary levels of analysis. The first one is a comprehensive low-cost screening, in order to detect unknown subsidence phenomena over large areas. This analysis, which provides a first estimation of deformations, has to be performed using a limited set of SAR images. The second level includes an in-depth quantitative analysis based on large image stacks, which requires more image acquisition and data processing resources. This type of analysis can be typically used to study deformation phenomena of special relevance, where an effective support to the decision-makers requires a fully quantitative estimation of deformations. The two levels of analysis were proved over a test area of about 2100 km2, located in Catalonia (Spain). Without any a priori information, seven deformation phenomena were detected using a reduced set of interferograms. Furthermore, the quantitative analysis of a subsidence of small spatial extent, which was based on ascending and descending datasets, confirmed the capability of DInSAR to quantitatively assess deformation phenomena.
Keywords
Subsidence;
Deformation;
Monitoring;
Remote sensing;
SA
Application of the differential interferometric technique (DInSAR) to unrevel the present-day vertical movement in the Gluckstadt graben, Germany
No full textDue Differenti Approcci Per L'analisi Degli Spostamenti Verticali Mediante Tecnica Dinsar
No full textCoupling geophysical modelling and geodesy to unravel the physics of active faults
No full textThe major requirements of seismic hazard assessment must address mainly the information about the expected location, time and magnitude of the impending strong earthquakes, as well as the scenarios ground motion associated with the possible future seismic events. While the quick notification of seismic events, appears nowadays pretty well established, thanks to the development of regional and local seismic networks, in terms of prevention more and more importance is devoted to studies of the inter- and pre- seismic earthquake cycle. To improve the intra seismic and pre-seismic information, which may lead to an effective mitigation of seismic risk, we are proposing an innovative approach, that combines Earth Observation data (GPS and SAR) and new advanced approaches in seismological and geophysical data analysis. The employed EO data are the observations acquired by means of SAR sensors, treated by Differential Interferometric techniques, the data observation acquired by permanent GPS stations or ldquoad-hocrdquo campaigns of the observations done over earthquake prone area. The aim is to combine the geophysical modelling of the faults with the surface displacement measured with the two mentioned techniques. In particular, application of the DInSAR techniques, using a stacking of interferograms, makes it possible, under the classical interferometric constraints (coherence, baseline, etc.), to retrieve a vertical displacements map, referred to a temporal interval, over areas where seismic fault system are localized. The displacements fields coming from GPS/DInSAR and other additional information, constitute the input for the geophysical model which shall indicate whether the fault is in a ldquocritical situationrdquo
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
- …
