A nonlinear Lagrangian particle model for grains assemblies including grain relative rotations     

Emilio Turco  Francesco dell'Isola  Anil Misra 《国际地质力学数值与分析法杂志》2019,43(5):1051-1079

We formulate a discrete Lagrangian model for a set of interacting grains, which is purely elastic. The considered degrees of freedom for each grain include placement of barycenter and rotation. Further, we limit the study to the case of planar systems. A representative grain radius is introduced to express the deformation energy to be associated to relative displacements and rotations of interacting grains. We distinguish inter-grains elongation/compression energy from inter-grains shear and rotations energies, and we consider an exact finite kinematics in which grain rotations are independent of grain displacements. The equilibrium configurations of the grain assembly are calculated by minimization of deformation energy for selected imposed displacements and rotations at the boundaries. Behaviours of grain assemblies arranged in regular patterns, without and with defects, and similar mechanical properties are simulated. The values of shear, rotation, and compression elastic moduli are varied to investigate the shapes and thicknesses of the layers where deformation energy, relative displacement, and rotations are concentrated. It is found that these concentration bands are close to the boundaries and in correspondence of grain voids. The obtained results question the possibility of introducing a first gradient continuum models for granular media and justify the development of both numerical and theoretical methods for including frictional, plasticity, and damage phenomena in the proposed model.  相似文献   

Contribution of deep dark fixation processes to overall CO2 incorporation and large vertical changes of microbial populations in stratified karstic lakes     

Emilio O. Casamayor  Marc Llirós  Antonio Picazo  Albert Barberán  Carles M. Borrego  Antonio Camacho 《Aquatic Sciences - Research Across Boundaries》2012,74(1):61-75

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Centrifuge modelling of the seismic performance of soft buried barriers     

Valeria Nappa  Emilio Bilotta  Alessandro Flora  S. P. Gopal Madabhushi 《Bulletin of Earthquake Engineering》2016,14(10):2881-2901

The paper presents the results of an experimental work carried out in a geotechnical centrifuge at the Schofield Centre of Cambridge University. Two reduced scale models of soft barriers in a sand layer underwent a series of ground shaking. In the first model a thin horizontal layer made of latex balloons filled with a cross-linked gel was created at about mid-height of the sand layer. In the second, the same balloons were deployed to form a V-shaped barrier aimed at isolating a relatively shallow volume of sand. The aim of the study was to get experimental evidence of the capability of such soft barriers to isolate a volume of soil thus reducing amplification of ground motion during severe seismic events. The experimental results were compared with FE numerical analyses of the same models, carried out also in free field to have a benchmark condition. By validating the FE modelling via the comparison with the experimental results, a robust model has been built, aimed at being used for carrying out a wider parametric numerical testing. The experimental results confirm the effectiveness of such soft barriers to reduce amplification in the isolated volumes during seismic events.  相似文献   

Recruitment,habitat selection and larval photoresponse of Paraleucilla magna (Porifera,Calcarea) in Rio de Janeiro,Brazil     

André Padua  Emilio Lanna  Carla Zilberberg  Paulo César de Paiva  Michelle Klautau 《Marine Ecology》2013,34(1):56-61

Little is known about the recruitment and behaviour of sponge larvae, especially of the class Calcarea. The calcareous sponge Paraleucilla magna is very common in Southeast Brazil, where it is considered a cryptogenic species. This study quantified recruitment rates in shaded and illuminated habitats for 2 years in Rio de Janeiro, Brazil, and analyzed larval photoresponses of this species. Four structures, each containing a shaded and an illuminated surface, were exchanged every 3 months for 2 years. The number of recruits was quantified on each plate. In the laboratory, larvae of P. magna were placed in half‐shaded Petri dishes and the number of settlers in each side was counted after 24 h. Paraleucilla magna recruited continuously throughout the experiment. Recruits occurred in greater abundance on shaded surfaces than on illuminated surfaces, and the larvae were negatively phototactic in vitro. Despite the possible influence of other factors in the recruitment of sponges (such as sedimentation, competition and predation), the prevalence of P. magna in shaded habitats may also be related to larval choice.  相似文献   

Turning the curve: A critical review of Kuznets approaches   总被引：1，自引：0，他引：1  

Rinku Roy Chowdhury  Emilio F. Moran 《Applied geography (Sevenoaks, England)》2012,32(1):3-11

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Aquifer vulnerability and potential risk assessment: application to an intensely cultivated and densely populated area in Southern Italy     

Gianluigi Busico  Emilio Cuoco  Maurizio Sirna  Micòl Mastrocicco  Dario Tedesco 《Arabian Journal of Geosciences》2017,10(10):222

The use of indices, describing aquifer vulnerability and the risk of groundwater pollution, is a basic tool for the implementation of a sound water management plan, especially in densely populated and intensely cultivated areas. In this study, the groundwater contamination risk of the Caserta Plain (Southern Italy) was assessed through the integration of hazards defined on the basis of the different land uses, of the intrinsic vulnerability calculated by applying the SINTACS model and of the groundwater value evaluated by considering water wells density. In order to evaluate the evolution of the risk of groundwater pollution, the proposed methods were applied in the study area for both 2001 and 2009. The resulting specific vulnerability (SINTACS-L) and the risk (GRA) maps, created in a GIS environment, were validated by the comparison with the nitrate concentration distribution. The application of the proposed approach to the study area highlighted the strengths and weaknesses of each method and, at the same time, showed that their combination can provide an overall view of the threats posed to groundwater resources by the human activities affecting the territory. Considering both the benefits and the issues of the proposed approach, overall, the groundwater risk map is thought to be a robust tool to support water managers in defining future plans for water resources exploitation and land use.  相似文献   

Fluid geochemistry of the Mondragone hydrothermal systems (southern Italy): water and gas compositions vs. geostructural setting     

Cuoco  Emilio  Minissale  Angelo  Di Leo  Antonella “Magda”  Tamburrino  Stella  Iorio  Marina  Tedesco  Dario 《International Journal of Earth Sciences》2017,106(7):2429-2444

International Journal of Earth Sciences - The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the...  相似文献   

Reversal records from Eastern Icelandic lava flows and their geodynamic significance     

Emilio Herrero-Bervera  George P. L. Walker  Christopher G. A. Harrison  Jose C. Guerrero Garcia 《Surveys in Geophysics》1996,17(2):197-206

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Olduvai termination: detailed palaeomagnetic analysis of a north central Pacific core     

Emilio Herrero-Bervera  M. A. Khan 《Geophysical Journal International》1992,108(2):535-545

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Sopra un'onda lenta superficiale provocata da esplosione vicina: I     

Dott. Ing. Emilio Perri 《Pure and Applied Geophysics》1954,27(1):7-29

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