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541.
This article describes a methodology to analyse debris-flow risk in the torrential watersheds of the southern hillside of
Gargano (Puglia—Italy). The approach integrates a stability model that identifies the areas of potential shallow landslides
in different meteorological conditions with a two-dimensional flood routing model that allows hazard mapping and GIS interface.
The results were combined with a susceptibility map that was defined by analyzing the vulnerability conditions and the exposure
of the alluvial fan. The models were calibrated on the 1972, July catastrophic event for which the distribution of rainstorm
intensity was available. The geo-mechanical properties of the debris were studied by field surveys and laboratory tests while
the sediment source areas and the shape of the alluvial cone were obtained using photo-aerial interpretation. The risk conditions
of the areas under consideration were also investigated in order to plan and guide measures aimed at limiting the damage such
hazards may cause. 相似文献
542.
Neural networks and landslide susceptibility: a case study of the urban area of Potenza 总被引:4,自引:1,他引:3
For those working in the field of landslide prevention, the estimation of hazard levels and the consequent production of thematic
maps are principal objectives. They are achieved through careful analytical studies of the characteristics of landslide prone
areas, thus, providing useful information regarding possible future phenomena. Such maps represent a fundamental step in the
drawing up of adequate measures of landslide hazard mitigation. However, for a complete estimation of landslide hazard, meant
as the degree of probability that a landslide occurs in a given area, within a given space of time, detailed and uniformly
distributed data regarding their incidence and causes are required. This information, while obtainable through laborious historical
research, is usually partial, incomplete and uneven, and hence, unsatisfactory for zoning on a regional scale. In order to
carry this out effectively, the utilization of spatial estimation of the relative levels of landslide hazard in the various
areas was considered opportune. These areas were classified according to their levels of proneness to landslide activity without
taking recurrence periods into account. Various techniques were developed in order to obtain upheaval numerical estimates.
The method used in this study, which was applied in the area of Potenza, is based on techniques derived from artificial intelligence
(Artificial Neural Network—ANN). This method requires the definition of appropriate thematic layers, which parameterize the
area under study. These are recognized by means of specific analyses in a functional relationship to the event itself. The
parameters adopted are: slope gradient, slope aspect, topographical index, topographical shape, elevation, land use and lithology. 相似文献
543.
544.
Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea 下载免费PDF全文
Ilaria Pizzetti Giuliano Lupini Fabrizio Bernardi Aubry Francesco Acri Bernhard M. Fuchs Stefano Fazi 《Marine Ecology》2016,37(6):1386-1397
The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities. 相似文献
545.
546.
A constitutive model for dry metamorphosed snow is proposed, within the framework of elasto‐viscoplasticity, which is able to reproduce the most relevant features of the macroscopic behaviour of snow, particularly its time and rate dependency. The basic ideas for modelling stem from the conceptual forms proposed for bonded geomaterials, such as cemented soils or soft rocks. The high viscosity of snow is accounted for by adopting an overstress approach, suitably modified. An evolution law for the curvature‐driven process of sintering, by which intergranular ice necks form and grow, is established. The system of constitutive equations is then numerically integrated via a fully implicit time stepping scheme. Selected results from finite element simulations of laboratory tests, available in the literature, are presented. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
547.
548.
Federico Di Traglia Chiara Del Ventisette Mauro Rosi Francesco Mugnai Emanuele Intrieri Sandro Moretti Nicola Casagli 《地学学报》2013,25(3):192-198
At Stromboli volcano (Southern Italy), only few minor precursors (gas output) have been identified for ‘major’ Strombolian explosions. We use ground‐based interferometric synthetic aperture radar (GBInSAR) technology to monitor the displacement rate of the summit area of Stromboli. We analysed the 2009–2011 period. The analysis of the displacement rate has been performed by dividing the summit zone monitored by the GBInSAR into three regions, corresponding to the edge of the crater area (1 and 2), and to the slope of the NE crater (3). Pulses of rapid expansion of sector 3, of variable duration and amplitude, appear in coincidence with periods of intense activity that include lava flows and major explosions. We associate this expansion with the pressurization of the magma column that is recharged by deep‐derived gas, promoting the onset of ‘major explosion‐dominated’ activity. 相似文献
549.
Roberto Ambrosini Pietro Bolli Claudio Bortolotti Francesco Gaudiomonte Filippo Messina Mauro Roma 《Experimental Astronomy》2010,27(3):121-130
Apart from externally generated Radio Frequency Interference (RFI), the occurrence of self-interference is a major concern
at any modern radio telescope site. Antenna servo motor controllers, data acquisition processors, and fast computing capabilities
operate very close to extremely sensitive and wideband radio astronomical receivers. In this paper, we present a set of measurements
of the RFI level generated by a cluster of computers that will be installed at the site of the Sardinia Radio Telescope (SRT).
The measured levels are compared to Recommendation ITU-R RA.769-2, which gives the threshold levels for interference detrimental
to radio astronomy observations. Our analysis shows that, with proper shielding of the noisiest devices, it will be possible
to preserve the present excellent RFI conditions of the SRT site. 相似文献
550.
J. V. Buckle E. I. Curtis J. F. Roberts G. J. White J. Hatchell C. Brunt H. M. Butner B. Cavanagh A. Chrysostomou C. J. Davis A. Duarte-Cabral M. Etxaluze J. Di Francesco P. Friberg R. Friesen G. A. Fuller S. Graves J. S. Greaves M. R. Hogerheijde D. Johnstone B. Matthews H. Matthews D. Nutter J. M. C. Rawlings J. S. Richer S. Sadavoy R. J. Simpson N. F. H. Tothill Y. G. Tsamis S. Viti D. Ward-Thompson J. G. A. Wouterloot J. Yates 《Monthly notices of the Royal Astronomical Society》2010,401(1):204-222
The Gould Belt Legacy Survey will survey nearby star-forming regions (within 500 pc), using Heterodyne Array Receiver Programme (HARP), Submillimetre Common-User Bolometer Array 2 and Polarimeter 2 on the James Clerk Maxwell Telescope. This paper describes the initial data obtained using HARP to observe 12 CO, 13 CO and C18 O J = 3 → 2 towards two regions in Orion B, NGC 2024 and NGC 2071. We describe the physical characteristics of the two clouds, calculating temperatures and opacities utilizing all the three isotopologues. We find good agreement between temperatures calculated from CO and from dust emission in the dense, energetic regions. We determine the mass and energetics of the clouds, and of the high-velocity material seen in 12 CO emission, and compare the relative energetics of the high- and low-velocity material in the two clouds. We present a clumpfind analysis of the 13 CO condensations. The slope of the condensation mass functions, at the high-mass ends, is similar to the slope of the initial mass function. 相似文献