1,355,210 research outputs found
Unsupervised Rank-deficient Density Estimation via Multi-Class Independent Component Analysis
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Remote Monitoring of Civil Infrastructure Based on TomoSAR
No full textStructural health monitoring and damage detection tools are extremely important topics nowadays with the civil infrastructure aging and deteriorating problems observed in urban areas. These tasks can be done by visual inspection and by using traditional in situ methods, such as leveling or using traditional mechanical and electrical sensors, but these approaches are costly, labor-intensive and cannot be performed with a high temporal frequency. In recent years, remote sensing has proved to be a very promising methodology in evaluating the health of a structure by assessing its deformation and thermal dilation. The satellite-based Synthetic Aperture Radar Tomography (TomoSAR) technique, based on the exploitation of a stack of multi-temporal SAR images, allows to remotely sense the movement and the thermal dilation of individual structures with a centimeter-to millimeter-level accuracy, thanks to new generation high-resolution satellite-borne sensors. In this paper, the effectiveness of a recently developed TomoSAR technique in assessing both possible deformations and the thermal dilation evolution of man-made structures is shown. The results obtained using X-band SAR data in two case studies, concerning two urban structures in the city of Naples (Italy), are presented
STUDY OF DEEP DYNAMIC IN THE LIGURO-PROVENÇAL SUBBASIN DURING WINTER 2005-2006
No full textHistorical data have identified the Gulf of Lion as the main important site for the formation of dense water responsible for the ventilation of the deep water in the western Mediterranean basin. report interesting episodes of deep convection also in the Ligurian Sea indicating significant changes in temperature and salinity of the Western Mediterranean Deep Water (Smith et al 2008, Marty et al 2010).
Between 2004 and 2009, in the framework of the ENVAR long term monitoring program, six moorings were deployed along a distance of about 70 km and at variable depths starting from 500 m down to 2300 m. Although the primary goal of the project was the study of the Var submarine canyon system, a large amount of current data were also gathered. This led to the realization of a long term series essential to characterize the deep dynamics of this area.
The analysis of this huge current dataset revealed long periods of strong near bottom currents not attributable to the turbidity flows acting along the submarine canyon, but rather imputable to processes of water sinking due to lateral mixing or pushed down by surface forcing. This is the case of the event recorded from February 2006, which shows abrupt increases of current speed (with peaks reaching 40 cm s-1) persisting for more than four months. This variation, recorded simultaneously by all current meters deployed, highlighted the occurrence of a mesoscale phenomenon whose effects transfer on a vast thickness of the water column (about 500 m). In support of this study, monthly hydrological profiles of temperature and salinity were retrieved from the Ifremer SISMER (Système d’Informations Scientifiques pour la MER) data bank.
The combined analysis of both hydrographic and current data allowed us to obtain a synoptical view of the events acting in the whole Var area and to verify that the strong current speed signals measured on winter 2006 may be effectively related to deep convection processes already observed in this area and not only to the activity of the submarine Var canyon
Searching for a binary factorial code using the ICA framework
No full textA binary factorial code is a transformation that maps the input space into a binary string with independent bits. We apply independent component analysis, formulated as a density search, to the pursuit of such a code by considering a set of desired output bi-modal density functions. The idea is tested on a real image with the coder used also in a reversed order as a generative model. The results are also compared to a principal component analyzer. Fantasy blocks of the image transforms provide interesting clues on the nature of the learned representations.
A binary factorial code i a transformation that maps the input space into a binary string with independent bits. We apply independent component analysis, formulated as a destiny search, to the pursuit of such a code by considering a set of desired output bi-modal density functions. The idea is tested on a real image with the coder used also in a reversed order as a generative model. The results are also compared to a principal component analyzer. Fantasy blocks of the image transforms provide interesting clues on the nature of the learned representations
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