1,448 research outputs found
Labor Income and Risky Assets under Market Incompleteness: Evidence from Italian Data
Theory suggests that uninsurable income risk induces individuals to accumulate assets as a precautionary reserve of value. Most assets, however, bear rate of return risk, that can be diversified only if every asset is traded by a large number of individuals and arbitrage is frictionless. Using Italian micro-data, we find evidence of income and asset risks that affect consumption. Italian households are particularly well insured against illness but not against job losses. Moreover, we detect a positive, yet weak, effect of asset holding on the variability of consumption streams across households.incomplete markets, consumption insurance, precautionary saving, financial markets, equity premium puzzle
Development of Models for On-line Diagnostic and Energy Assessment Analysis of PV Power Plants: The Study Case of 1 MW Sicilian PV Plant
Abstract For photovoltaic (PV) power plants, every kilowatt-hour is important, because only kilowatt-hours that are fed into the grid are remunerated. A plant's operator can only adopt prompt measures to eliminate operational faults when these are immediately signaled. In fact, just reading the feed-in meter each month is not sufficient to promptly recognize faults and to avoid the loss of yields. Many inverters record the most important operational data, automatically evaluate the data and, in case of a fault, send the operator notifications via email or text message. However, it only allows obvious faults to be recorded. On the other hand, continuous, absolute and comparative measurements are necessary to ensure the maximum efficiency and availability. Based on real time and historical data, a technical plant manager should inform the operators of any fault which occurs or even take independent measures to rectify it. In this context, suitable models are developed and applied to a 1 MW power plant where a SCADA, Supervisory Control And Data Acquisition, has been installed and operational data are available on a Web page. In order to evaluate the performance of the PV system, firstly the daily corrected Performance ratio has been evaluated. Then, different approaches to estimate the AC and the DC power of the PV plant have been developed. Basing on the difference between the measured and the estimated power, a statistical approach is proposed; it allows to define suitable thresholds on the AC and DC power in order to individuate a fault when occurs. The experimental results show the effectiveness of the proposed approach
Monitoring and structural significance of ground deformations at Campi Flegrei supervolcano (Italy) from the combined 2D and 3D analysis of PS-InSAR, geophysical, geological and structural data
Cities are growing around active volcanoes. Campi Flegrei supervolcano (CF, Italy) is a nested structure formed during two main collapses associated with two caldera-forming eruptions at 39 ka and 15 ka. The last event occurred in AD
1538 (Monte Nuovo volcano). CF hosts 350,000 people and two main uplift phases were recorded in 1968â1972 and
1982â1984 with deformations of about 2 m. The town of Pozzuoli was partially evacuated during the last crisis.
Subsequent minor deformations (subsidence and uplift), seismicity, and diffuse CO2 degassing concentrate in the central
part of the caldera. Here, we apply the Permanent Scatterers Synthetic Aperture Radar Interferometry (PS-InSAR) to
investigate the ground deformations of CF by using data acquired from 1993 to 2007 from ascending and descending
tracks by ERS-1 ,ERS-2 and RADARSAT satellites. Deformation maps identify a subsidence interrupted by micro-uplift
episodes. These maps are combined with digitized topographic, geological (faults and landslides), seismic, and
urbanization data. The merged information allow us to identify the areas involved in the deformation and the volcanotectonic
structures activated during the uplift and subsidence episodes. We propose a structural-volcanological model for the unrest pisodes. Data indicate that uplift episodes, which re associated to seismicity, are followed by subsidence
episodes accommodated by pre-existing faults. The urbanized areas subjected to the higher deformations and shaking are
also identified and mapped. A multi-hazard zonation including landslides is also provided. The approach used here may
be utilized to (a) recognize the tectonic and/or volcanic structures activated during ground deformations, (b) to
investigate structural models, (c) to evaluate and map multi-risk zonations, and (c) monitor other volcanic areas or nonvolcanic zones subjected to gravity instability or tectonics
Source and dynamics of a volcanic caldera unrest : Campi Flegrei, 1983â84
Acknowledgements We thank Tiziana Vanorio, Antonella Amoruso, Luca Crescentini, Nicholas Rawlinson, Yasuko Takei, and David Cornwell for the valuable suggestions regarding the methodology and interpretation. Reviews from Tim Greenfield and two anonymous reviewers helped improving both clarity of the manuscript and interpretation. The Royal Society of Edinburgh - Accademia dei Lincei Bilateral Agreement, the Santander Mobility Award of the College of Physical Sciences, University of Aberdeen, and the TIDES EU COST action granted L.D.S. travel grants for the realisation of this study. E.D.P. has been supported by the EPHESTO and KNOWAVES projects, funded by the Spanish Ministry of Education and Science.Peer reviewedPublisher PD
Morphometry of the Campi Flegrei caldera (Southern Italy)
A high-resolution Digital Terrain Model (DTM) of Campi Flegrei caldera, obtained from an airborne LiDAR mission, has been analyzed in order to produce a 1:20,000-scale morphometric map of this volcanic area. The map consists of different thematic layers, which include: profile curvature, terrain ruggedness index, elevation range, as well as an up-to-date structural map and building distribution in the densely populated area. Results evidence that most of the relief is related to the occurrence of tuff-cones, tuff-ring, and the outer flanks of the caldera. Higher values of elevation characterize the upper portions of cones, while higher terrain ruggedness index values concentrate on the inner flanks of cones and in areas affected by gravity and erosional processes. The map also evidences the topographic expression of crater rims and of the major morphological scarps, which reflect ancient and uplifted shorelines and present-day cliffs
Estimates of fluid pressure and tectonic stress in hydrothermal/volcanic areas:a methodological approach
An analytical approach to estimate the relative contribution of the fluid pressure and tectonic stress in hydrothermal/
volcanic areas is proposed assuming a Coulomb criterion of failure. The analytical procedure requires the
coefficient of internal friction, cohesion, rock density, and thickness of overburden to be known from geological
data. In addition, the orientation of the principal stress axes and the stress ratio must be determined from the
inversion of fault-slip or seismic data (focal mechanisms). At first, the stress magnitude is calculated assuming
that faulting occurs in 'dry' conditions (fluid pressure=0). In a second step, the fluid pressure is introduced performing
a grid search over the orientation of 1) fault planes that slip by shear failure or 2) cracks that open under
different values of fluid pressure and calculating the consistency with the observed fault planes (i.e. strike
and dip of faults, cracks, nodal planes from focal mechanisms). The analytical method is applied using fault-slip
data from the Solfatara volcano (Campi Flegrei, Italy) and seismic data (focal mechanisms) from the Vesuvius
volcano (Italy). In these areas, the fluid pressure required to activate faults (shear fractures) and cracks (open
fractures) is calculated. At Solfatara, the ratio between the fluid pressure and the vertical stress ?is very low for
faults ( ?=0.16) and relatively high for cracks ( ?=0.5). At Vesuvius, ?=0.6. Limits and uncertainties of the
method are also discussed
RAST: RoundAbout Solar Tracking
Abstract Roundabouts became popular worldwide as a tool to reduce the number of car accidents and the EU encourages and promotes this technology as a solution to the problems of urban and extra-urban traffic. RAST (Roundabout Solar Tracking) systems are designed to exploit the available space in roundabouts, which are already equipped and monitored, in order to produce electricity with a photovoltaic single axis tracking system. The energy produced can be used directly by the surrounding facilities or stored and consumed later or channelled to nearby car charge points. The amount of energy that can be produced on a single roundabout is limited by the land size and is normally in the range 100-400 kWp, but the number of suitable roundabouts in cities is high. Therefore, RAST could make an important contribution to the energy production
Evaluation of an additive efficacy in broiler litter microbial level control in field: preliminary results
The present study was conducted to evaluate in field the efficacy of an additive (SOPÂź C POULTRY), as an agent for the control of micro-organisms in broiler litter. The Total aerobic Microbial Count (TMC), Staphylococcus species (spp.), Coliforms, and Salmonella spp. in broiler litter samples of both the Houses, 2 (H2) and 3 (H3), were determined, and also at the end of each cycle the mortality rate was recorded. The results showed significant reduction of all the microbial counts: P= 0.0078 (CMT), 0,0021 (Staphylococcus spp.) and 0.0541 (Coliforms), and mortality (P= 0.00106) in treated litter samples H2 and the control H3
BNaâBLi solid-solution in A-site-vacant amphiboles: synthesis and cation ordering along the ferri-clinoferroholmquistiteâriebeckite join.
Amphiboles were hydrothermally synthesized at 500 âC and 4 kbar in the system Li2O-Na2OFeO- Fe2O3-SiO2-H2O, with nominal compositions along the riebeckite [â Na2Fe3 2+ Fe2 3+Si8O22(OH)2]-ferri-clinoferroholmquistite [â Li2Fe3 2+Fe2 3+Si8O22(OH)2] join, where the exchange vector is NaLiâ1 at the B-site. Experimental products were characterized by powder XRD and SEM-EDAX, confirming very high amphibole yield along the join (>95%, plus minor quartz). The XRD patterns can be indexed in C2/m, and the refined cell parameters show linear variation as a function of composition. For the BLi end-member, the IR spectrum shows a single sharp main band centered at 3614 cmâ1, which is assigned to the FeFeFe-OH-Aâ configuration. With increasing BNa in the mineral, this band broadens and shifts 4 cmâ1 to higher frequencies. This effect can be attributed to the change in M4 site occupancy. Minor ANa (partial solid-solution toward arfvedsonite) is also observed with increasing sodium in the system. Mössbauer spectroscopy confirms the cation distribution provided by IR data, and shows that a small, but significant amount of Fe2+ occurs at M4 along the join. Infrared spectroscopy shows that the Li end-member has a very ordered structure, whereas intermediate compositions show local heterogeneities associated with the presence of two different B sites occupied by Na or Li
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