Structural response to non-stationary multiple-support random excitation     

Federico Perotti 《地震工程与结构动力学》1990,19(4):513-527

The seismic behaviour of large-size structures subjected to multiple-support excitation is studied by means of a random vibration approach. Ground motion is modelled as a non-stationary stochastic process having an evolutionary spectral density. To describe the spatial variability of the input motion a model is adopted which accounts for finite propagation velocity and for loss of correlation as a function of distance and frequency. Structural analysis is entirely performed in the frequency domain and full advantage is taken of FFT properties and capabilities. An example is given regarding the behaviour of a 800 m long viaduct. Results are shown in terms of response evolutionary spectral density, variance and reliability with respect to a fixed threshold.  相似文献   

Back Analysis of the 2014 San Leo Landslide Using Combined Terrestrial Laser Scanning and 3D Distinct Element Modelling     

Margherita Cecilia Spreafico  Mirko Francioni  Federico Cervi  Doug Stead  Gabriele Bitelli  Monica Ghirotti  Valentina Alena Girelli  Claudio Corrado Lucente  Maria Alessandra Tini  Lisa Borgatti 《Rock Mechanics and Rock Engineering》2016,49(6):2235-2251

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The effectiveness of high-resolution LiDAR data combined with PSInSAR data in landslide study   总被引：1，自引：0，他引：1  

Andrea Ciampalini  Federico Raspini  William Frodella  Federica Bardi  Silvia Bianchini  Sandro Moretti 《Landslides》2016,13(2):399-410

The spatial resolution of digital elevation models (DEMs) is an important factor for reliable landslide studies. Multi-interferometric techniques such as persistent scatterer interferometric synthetic aperture radar (PSInSAR) are used to evaluate the landslide state of activity and its ground deformation velocity, which is commonly measured along the satellite line of sight (LOS). In order to compare velocities measured by different satellites in different periods, their values can be projected along the steepest slope direction, which is the most probable direction of real movement. In order to achieve this result, DEM-derived products are needed. In this paper, the effectiveness of different DEM resolutions was evaluated in order to project ground deformation velocities measured by means of PSInSAR technique in two different case studies in the Messina Province (Sicily, southern Italy): San Fratello and Giampilieri. Three DEMs were used: (i) a 20-m resolution DEM of the Italian Military Geographic Institute (IGM), (ii) a 2-m resolution DEM derived from airborne laser scanning (ALS) light detection and ranging (LiDAR) data for the San Fratello 2010 landslide, and (iii) a 1-m resolution DEM derived from ALS LiDAR data for the area of Giampilieri. The evaluation of the applied method effectiveness was performed by comparing the DEMs elevation with those of each single permanent scatterer (PS) and projecting the measured velocities along the steepest slope direction. Results highlight that the higher DEM resolution is more suitable for this type of analysis; in particular, the PS located nearby the watershed divides is affected by geometrical problems when their velocities are projected along the steepest slope.  相似文献   

Tropicality,the unruly Atlantic and social utopias: the French explorer Henri Coudreau (1859 − 1899)          下载免费PDF全文

Federico Ferretti 《Singapore journal of tropical geography》2017,38(3):332-349

This paper addresses the works of Henri Coudreau, a little‐known French explorer of Guiana and Amazonia who was later forgotten by the ‘heroic’ histories of exploration because of his unruliness and nonconformist attitudes. Drawing on the literature of postcolonialism and tropicality as well as on recent studies of anti‐colonialist geographies, I address for the first time Coudreau's geography from the perspective of anarchist and critical thinking. My main argument is that Coudreau's work is a further example of the complexity and heterogeneity of the European intellectual field during the imperial age. Despite having come of age intellectually among all the European racist and ethnocentric prejudices of his day, Coudreau developed a different outlook thanks to two factors, viz., his personal experience in living for years with the indigenous communities of Amazonia, and his exposure to anarchist anti‐colonialist ideas through his collaboration with Elisée Reclus. Coudreau's tropical utopia of an independent Amazonia, and his endorsement of the stateless nature of local communities, ran counter to French imperial politics, occasioning Coudreau's dismissal from the French administration and his professional exile in Brazil at the time of the Franco‐Brazilian border dispute (1897?1900).  相似文献   

The Lago di Varano: Hydrologic Characteristics and Sediment Composition     

Federico Spagnoli  Antonietta Specchiulli  Tommaso Scirocco  Gerardo Carapella  Paolo Villani  Giovanni Casolino  Primiano Schiavone  Massimo Franchi 《Marine Ecology》2002,23(S1):384-394

Abstract. The Lago di Varano is situated on the north side of the Gargano National Park (southeast Italy) and covers a surface area of about 65 km². It communicates with the Adriatic Sea through two artificial canals (Foce Capoiale and Foce Varano) located at the two ends of a long and narrow coastal dune. This work presents preliminary results of four seasonal surveys (1999–2000) carried out to measure chemical and physical parameters of the water column (temperature, salinity, dissolved oxygen and pH) and to analyse a number of biogeochemical characteristics of surface sediments (organic matter, total phosphorus, total nitrogen and total Hg, As, Pb, Cd, Cr, Cu and Ni content). Water analysis indicated poor exchange between the coastal pond and the open sea, limited to autumn and winter. Surface sediments were rich in organic matter, whose distribution was influenced by chemical-physical and hydrodynamic variations in the water column. At the sediment level, the highest values of Cd were found in the central zone of the basin, while the highest Cr values were measured in the central and southeastern areas. With the exception of Cd and Pb, the metal content did not indicate anthropogenic pollution, in particular when compared with the Venice Lagoon and the Central Adriatic Sea.  相似文献   

Re‐orientation of the extension direction and pure extensional faulting at oblique rift margins: comparison between the Main Ethiopian Rift and laboratory experiments     

Giacomo Corti  Melody Philippon  Federico Sani  Derek Keir  Tesfaye Kidane 《地学学报》2013,25(5):396-404

In this study, we draw on a unique combination of well‐resolved fault‐slip data and earthquake focal mechanisms to constrain spatial variations in style of faulting in the obliquely extending Main Ethiopian Rift, East Africa. These data show that both boundary and internal faults – oblique and orthogonal to the plate divergence (PD) respectively – exhibit almost pure dip‐slip motion, and indicate significant local deflection in orientation of the extension direction at rift margins. Scaled analogue models closely replicate the multidisciplinary observations from the rift and suggest that the process is controlled by the presence of a deep‐seated, pre‐existing weakness – oblique to the direction of PD – that is able to cause a local rotation in the orientation of the extension direction at rift margins. Minor counterclockwise block rotations are required to accommodate the difference in slip direction along the different fault systems, as supported by existing and new palaeomagnetic data from the rift.  相似文献   

Three dimensional elasto‐plastic interface for embedded beam elements with interaction surface for the analysis of lateral loading of piles          下载免费PDF全文

Diego F. Turello  Federico Pinto  Pablo J. Sánchez 《国际地质力学数值与分析法杂志》2017,41(6):859-879

This paper presents a numerical formulation for a three dimensional elasto‐plastic interface, which can be coupled with an embedded beam element in order to model its non‐linear interaction with the surrounding solid medium. The formulation is herein implemented for lateral loading of piles but is able to represent soil‐pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The interface is formulated in order to capture localized material plasticity in the soil surrounding the pile within the range of small to moderate lateral displacements. The interface is formulated following two different approaches: (i) in terms of beam degrees of freedoms; and (ii) considering the displacement field of the solid domain. Each of these alternatives has its own advantages and shortcomings, which are discussed in this paper. The paper presents a comparison of the results obtained by means of the present formulation and by other well‐established analysis methods and test results published in the literature. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Geochemical evidence for sediment provenance in mudstones and fossil‐poor wackestones (Upper Jurassic,Majorca Island)     

Rute Coimbra  Federico Olóriz 《地学学报》2012,24(6):437-445

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A new method for laboratory estimation of the transverse dispersion coefficient     

Massabò M  Catania F  Paladino O 《Ground water》2007,45(3):339-347

We introduce a method for identifying the transverse dispersion coefficient in laboratory experiments based on the analytical solution of a pulse injection of a nonreactive solute in a soil column (cylindrical geometry) packed with a homogeneous porous medium. This method takes into account the effect of boundary conditions such as no flux on the column perimeter, and it does not need a priori knowledge of the longitudinal dispersion coefficient. Numerical applications of the method show that it is stable and robust and that the results are reasonably in accordance with those found using the classical maximum likelihood method.  相似文献   

Occurrence and seasonal variations of algal toxins in water, phytoplankton and shellfish from North Stradbroke Island, Queensland, Australia   总被引：4，自引：0，他引：4  

Takahashi E  Yu Q  Eaglesham G  Connell DW  McBroom J  Costanzo S  Shaw GR 《Marine environmental research》2007,64(4):429-442

A number of marine microalgae are known to produce toxins that can accumulate in shellfish and when eaten, lead to toxic and potentially fatal reactions in humans. This paper reports on the occurrence and seasonal variations of algal toxins in the waters, phytoplankton and shellfish of Southeast Queensland, Australia. These algal toxins include okadaic acid (OA), domoic acid (DA), gymnodimine (GD), pectenotoxin-2 (PTX-2) and pectenotoxin-2-seco acid (PTX-2-SA), which were detected in the sampled shellfish and phytoplankton, via HPLC-MS/MS. Dissolved OA, PTX-2 and GD were also detected in the samples collected from the water column. This was the first occasion that DA and GD have been reported in shellfish, phytoplankton and the water column in Queensland waters. Phytoplankton tows contained both the toxic Dinophysis and Pseudo-nitzschia algae species, and are suspected of being the most likely producers of the OA, PTX-2s and DA found in shellfish of this area. The number of cells, however, did not correlate with the amount of toxins present in either shellfish or phytoplankton. This indicates that toxin production by algae varies with time and the species present and that number of cells alone cannot be used as an indicator for the presence of toxins. The presence of OA and PTX-2s were more frequently seen in the summer, while DA and GD were detected throughout the year and without any obvious seasonal patterns.  相似文献