1,721,004 research outputs found
On the COSMO-SkyMed Exploitation for Interferometric DEM Generation
No full textDEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). Both SPOTLIGHT and STRIPMAP acquisition modes are analyzed through standard SAR Interferometry as well as multi-pass interferometry [4
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
Refined InSAR derived fault model for the Mw=6.3, June 15, 1995 Aigion EQ (Greece)
No full textThe detectability of the deformation pattern produced by the June 15, 1995 Aigion Earthquake with DInSAR techniques is ensured by its magnitude (MW = 6.3), shallow depth and dip-slip mechanism. In this paper, stacking procedures are applied to a series of ERS interferograms in order to filter out from the differential phase field the atmospheric signal, and an a posteriori test is used to check the statistical properties of the atmospheric signal both in time and space. Based on the DInSARderived deformation pattern, a new fault model is proposed that takes into account the crustal layering of the western part of the Gulf of Corinth
Postseismic Deformation Monitoring With the COSMO/SKYMED Constellation
No full textCOSMO/SKYMED is currently the unique constellation of synthetic aperture radar (SAR) sensors operative, which is also for civilian use. On April 6, 2009, an Mw 6.3 earthquake struck the city of l'Aquila in Central Italy. The constellation acquired data stacks over the hit area at an unprecedented temporal rate. In this letter, the results obtained by processing several data set via two independent multitemporal differential interferometric SAR techniques are presented to demonstrate the capability of this constellation in postseismic deformations monitoring
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
Rilevamento di deformazioni del suolo in Daunia (Puglia) per mezzo di tecniche interferometriche SAR
No full textIl lavoro presenta un’attività di ricerca condotta nell’ambito di un programma finanziato dalla Regione
Puglia e finalizzata all’impiego di tecniche interferometriche SAR per lo studio delle deformazioni
al suolo nel sub-appennino Dauno (Puglia). Tale area risulta di notevole interesse per la
Protezione Civile – Regione Puglia, che è uno dei potenziali utenti dei prodotti di deformazione ottenuti
dall’analisi multi-temporale interferometrica di immagini SAR acquisite da satellite.
I risultati sono ottenuti per mezzo della catena interferometrica SPINUA (Bovenga et al., 2004) che
implementa un approccio di tipo Riflettori Permanenti e rappresenta uno strumento efficace per ispezionare
periodicamente, su archi temporali di diversi anni, un vasto territorio al fine di rilevare
movimenti deformativi sub-verticali con cinematiche lente e con la precisione di pochi millimetri
all’anno per la velocità media. La catena di elaborazione è stata aggiornata negli ultimi anni per
consentire l’utilizzo di dati SAR di ultima generazione che, grazie all’alta risoluzione spaziale, aprono
nuove opportunità applicative.
Nell’articolo verranno presentati i primi risultati ottenuti elaborando dati acquisiti tra il 2002 ed il
2010 dal satellite ENVISAT dell’Agenzia Spaziale Europea (ESA) in banda C a media risoluzioneIn this paper we present the research activity carried out in the framework of a project funded by Puglia Region and aimed at using SAR Interferometry for measuring deformations induced by landslides in the Daunia region (Puglia). The area is of particular interest for the Civil Protection – Regione Puglia Authority which is one of the potential end users of the deformation map derived by multi-temporal interferometric analysis of satellite data. The results have been obtained through the SPINUA processing chain (Bovenga et al., 2004) which performs a multi-temporal InSAR Persistent Scatterer-like analysis. These approaches are able to inspect periodically a wide area on the ground measuring sub-vertical displacements with a precision of few millimetres per year for the mean velocity. The algorithm is also able to process the new generation of X-band high resolution SAR data. In the paper we present first results obtained by processing SAR data acquired between 2002 and 2010 by the ENVISAT ESA satellite which works at and medium spatial resolution
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
Refined fault model for the Mw=6.3, June 15, 1995 Aigion EQ (Greece) derived from InSAR data and implications for extensional tectonics of the western Corinth rift
No full textOn June 15th, 1995, a Mw= 6.3 earthquake struck the western part of the Gulf of Corinth with mainshock epicentre 16 km NNE from Aigion city. The present study presents the application of SAR interferometry (InSAR) techniques for obtaining the co-seismic deformation pattern and inferring the fault model parameters for this seismic event. A second objective is test the Rigo et al., (1996) model for active tectonics of the western Gulf. Both ascending (Track 279, Frame 2835) and descending (Track 415, Frame 765) ERS-1/2 SAR acquisitions were initially selected within 2 years from the mainshock, with the aim of investigating the area affected by the earthquake under different observation directions, different atmospheric conditions and during different seismic activity phases. Standard DInSAR processing was performed in order to produce a stack of differential interferograms. A SRTM DEM of the area was used to remove the topographic component from the interferometric phase. The data time distribution appears suitable for investigating possible pre- and post-seismic activity; however, both pre-shock and after-shock interferograms do not show evidence of any deformation pattern, as the dominant differential phase component seems principally due to atmospheric signal. An in-depth investigation of the co-seismic activity has been instead possible thanks to several suitable interferograms obtained by using both descending and ascending data. In both cases a co-seismic deformation pattern is clearly visible around Cape Psaromita. The spatial distribution of fringes seems in good agreement with that reported in the study of Bernard et al., 1997. However, atmospheric artefacts are recognizable, especially for daytime acquisitions. Therefore, a stacking procedure has been performed in order to filter out the atmospheric signal and to obtain a more reliable deformation pattern. Six complex descending differential interferograms were selected, generated from seven acquisitions acquired between 19 August 1993 and 23 June 1996. After phase offsets correction, a weighted average of the unwrapped interferograms was performed. The resulting differential interferogram contains mainly the temporally correlated displacement signal, while the temporally uncorrelated atmospheric components have been mostly filtered out. By using this refined interferometric pattern of the deformation field, measured along the Line Of Sight (LOS) of the ERS spacecrafts, forward and inversion procedures were performed in order to obtain a new reliable fault model for the Aigion EQ. This single fault plane solution represents a significant improvement of the Okada-like fault models proposed in Bernard et al., (1997), because the effect of the crustal layering of the western Gulf of Corinth was included in the fault model formulation and because of the smaller RMSe between measured and synthetic deformation pattern. Our main findings include: a) the 1995 earthquake did not occur along the onshore Aigion Fault b) the 1995 earthquake occurred along a low angle fault probably with increasing dip towards the surface c) the 1995 earthquake did not rupture the surface and d) the high-angle, antithetic faults of McNeil et al., (2005) terminate against the low angle fault
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