177,005 research outputs found
Satellite based radar interferometry to mapping and monitoring swelling/shrinking clay soils
No full textA methodology for the study of swelling/shrinkage through the satellite radar images acquired from 1992 to 2010 by different sensors (ERS, RADARSAT) and processed by means of the SqueeSARTM technique is proposed. The methodology aimed at improving the understanding of the kinematical behavior of swelling/shrinking processes, mapping these soils, monitoring the soil volume change and enabling also non-expert users to handle DInSAR data. The methodology has been applied and validated in an area of the Northern Italy where swelling/shrinking soils are frequent. The map of the ground displacements was compared with the geological model of the subsurface and with the distribution of the damaged buildings. The obtained results are helpful in land use planning to identify and quantify the swelling/ shrinkage of clay soils
A novel method for landslides investigation through A-DINSAR time series
No full textIn recent years, Advanced Differential Interferometric Synthetic-Aperture
Radar A-DInSAR technique has advanced rapidly for detecting and
monitoring ground surface deformations due to landslides. Identification
of the areas affected by ground motion through A-DInSAR data is generally
based on visual inspection and hotspot or cluster analysis of average
displacement rates. However, interpreting A-DInSAR time series of a
particular area provides a better indication of the real trend of displacement
of a landslide, while identifying the possible moment of acceleration of the
deformation process as well. A novel methodology is then proposed for
identifying different typologies of ground motion areas mainly related to
landslide phenomena at a regional scale, by means of A-DinSAR data at high
spatial and temporal resolutions. This methodological approach was tested
and validated in Piedmont region northern Italy, by means of RADARSAT
and COSMO-SkyMed satellite data, in both ascending and descending
modes. Linear constant in time displacement and non-linear acceleration
or deceleration in the displacement rate trends were recognised, allowing
characterisation of the kinematic pattern of a landslide or a portion of it. Local
and site-specific scale analyses, performed in an Alpine valley and in two
hillslopes representative of the main geological/geomorphological contexts
of the study area, validated the results obtained at the regional scale. This
supported the interpretation of the driving mechanism for such known
landslides, or other geological processes which can cause ground motion
along slopes. The developed procedure can allow one to specify priority
areas for prevention activities, in order to optimise the costs and benefits
of designing a plan to monitor instability phenomena at regional and sitespecific
scales. Moreover, ground motion areas identified by different sensors
in the same landslide help in the characterization of the state of activity of
this phenomenon, identifying also possible moments of re-activation
PSI-based methodology to land subsidence mechanism recognition
No full textA methodology based on Persistent Scatterer Interferometry (PSI) is proposed in order to disentangle the contribution of different processes that act at different spatio-temporal scales in land subsidence (i.e. vadose zone processes as swelling/shrinkage of clay soils, soil consolidation and fluid extraction). The methodology was applied in different Italian geological contexts characterized by natural and anthropic processes (i.e. a Prealpine valley and the Po Plain in northern Italy)
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Molecular basis of a novel renal amyloidosis due to N184K gelsolin variant
No full textMutations in gelsolin are responsible for a systemic amyloidosis first described in 1969. Until recently, the disease was associated with two substitutions of the same residue, leading to the loss of the calcium binding site. Novel interest arose in 2014 when the N184K variant of the protein was identified as the etiological agent of a novel kidney-localized amyloidosis. Here we provide a first rationale for N184K pathogenicity. We show that the mutation induces a destabilization of gelsolin second domain, without compromising its calcium binding capacity. X-ray data combined with molecular dynamics simulations demonstrates that the primary source of the destabilization is a loss of connectivity in proximity of the metal. Such rearrangement of the H-bond network does not have a major impact on the overall fold of the domain, nevertheless, it increases the flexibility of a stretch of the protein, which is consequently processed by furin protease. Overall our data suggest that the N184K variant is subjected to the same aberrant proteolytic events responsible for the formation of amyloidogenic fragments in the previously characterized mutants. At the same time our data suggest that a broader number of mutations, unrelated to the metal binding site, can lead to a pathogenic phenotype
Multi-sensor SAR data for landslide inventory updating: the case study of Piemonte Region
No full textIn the last decade, satellite radar differential interferometry (DInSAR) has been used in updating the landslides
inventories. The technique allows to monitor the deformation patterns over large areas, in order to verify and/or modify
the landslide boundaries. Moreover, it contributes to define the state of activity of a phenomenon. The improvements of
the SAR data, guaranteed by the COSMO-SkyMed satellites and by the future ESA Sentinel missions, that act at higher
spatio-temporal resolution, require appropriate methodologies for analyzing large datasets of points of measures.
To address to these problems, we present a guiding procedure to analyze multi-sensors SAR dataset with the aim of
updating landslides inventories. We applied the methodology in Piemonte region, a wide area of north-western Italy
affected by a big amount of different types of landslides. We use satellites images acquired, in ascending and descending
acquisition geometry, by C-band (ERS 1⁄2, ENVISAT, RADARSAT) and X-band (COSMO-SkyMed) sensors and
processed using SqueeSARTM, PSInSARTM and PSP-IfSAR techniques. The project was carried out in collaboration with
ARPA Piemonte and a part of the interferometric data were provided by the Italian Ministry of Environment in the frame
of the “Extraordinary Plan of Environmental Remote Sensing” (PST-A).
The developed methodology consists of three main steps: 1) post-processing elaborations of the SAR data, for
removing possible errors which could affect the dataset; 2) identification of the ground motion areas characterized by
different deformation style (i.e. lowering, uplift and non-linear trend) by the use of automatic and semi-automatic
statistical analysis, based on Principal Component Analysis, on the displacement time series; 3) analysis between the
identified ground motion areas and the landslides distribution (The Piemonte Landslide inventory–SIFRAP) both at
regional scale and at local scale, thanks to detailed in situ analysis for the most interesting sites.
Integrating multi-sensor SAR data collected for a continuous period of 24 years (from 1992 to 2015) provided
important information on the landslides detection at regional and local scales, in the different geological,
geomorphological and environmental contexts of the Piemonte region. Three study areas, where SAR images of all the
considered sensors were available, were selected for representing the main contexts of Piemonte region: the Susa (528
km2 wide) and the Orco-Lanzo (996 km2 wide) valleys, representative of the Alps domain; the western Turin hill (404
km2 wide), representative of the Turin hill context. The availability of the large archive of SAR data allowed the backmonitoring
of the time evolution of different phenomena. In particular, different phases of activation, re-activation,
acceleration or stabilization of the phenomena were recognized. In addition we have assessed the performance of the
multi-sensors SAR data for monitoring different landslides types
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part II: Port Area and Residential Area
No full textThis paper reports the second part of a simulation study with the aim of evaluating the ability of two portions of a hybrid AC/DC MV/LV network in maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, this paper follows a dual purpose: first, it analysis two microgrids in a residential area and a port zone capability of operating in islanded mode, applying a probabilistic approach, while there is different energy use cases, and second is to evaluate some reliability indicators
A Simulation Analysis for Assessing the Reliability of AC/DC Hybrid Microgrids - Part I: Underground Station and Car Parking
No full textThis paper reports the results of a simulation study with the aim of evaluating the capability of two portions of a hybrid AC/DC MV/LV network of maintaining their operation in off-grid mode during the loss of the main AC grid due to a failure. In particular, the study aims to verify, in the case of islanded operation of the two microgrids, the continuity of the electricity service by exploiting the local generation plants, Energy Storage Systems (ESSs), and other flexible resources managed by suitable algorithms in different energy scenarios. The analysis was carried out considering two microgrids: an underground station and a car parking with Electric Vehicles (EVs). For assessing the performance of the network, specific indicators have been defined and calculated
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