Gravity for Detecting Caves: Airborne and Terrestrial Simulations Based on a Comprehensive Karstic Cave Benchmark     

Carla Braitenberg  Daniele Sampietro  Tommaso Pivetta  David Zuliani  Alfio Barbagallo  Paolo Fabris  Lorenzo Rossi  Julius Fabbri  Ahmed Hamdi Mansi 《Pure and Applied Geophysics》2016,173(4):1243-1264

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GECO: a global gravity model by locally combining GOCE data and EGM2008   总被引：3，自引：0，他引：3  

Maddalena Gilardoni  Mirko Reguzzoni  Daniele Sampietro 《Studia Geophysica et Geodaetica》2016,60(2):228-247

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One‐dimensional and two‐dimensional hydrodynamic modeling derived flow properties: impacts on aquatic habitat quality predictions          下载免费PDF全文

Rohan Benjankar  Daniele Tonina  James McKean 《地球表面变化过程与地形》2015,40(3):340-356

Studies of the effects of hydrodynamic model dimensionality on simulated flow properties and derived quantities such as aquatic habitat quality are limited. It is important to close this knowledge gap especially now that entire river networks can be mapped at the microhabitat scale due to the advent of point‐cloud techniques. This study compares flow properties, such as depth and velocity, and aquatic habitat quality predicted from pseudo‐2D and fully 2D hydrodynamic modeling. The models are supported by high‐resolution, point‐cloud derived bathymetries, from which close‐spaced cross‐sections were extracted for the 1D modeling, of three morphologically and hydraulically different river systems. These systems range from small low‐gradient meandering pool–riffle to large steep confined plane‐bed rivers. We test the effects of 1D and 2D models on predicted hydraulic variables at cross‐sections and over the full bathymetry to quantify the differences due to model dimensionality and those from interpolation. Results show that streambed features, whose size is smaller than cross‐sectional spacing, chiefly determine the different results of 1D and 2D modeling whereas flow discharge, stream size, morphological complexity and model grid sizes have secondary effects on flow properties and habitat quality for a given species and life stage predicted from 1D and 2D modeling. In general, the differences in hydraulic variables are larger in the bathymetric than in the cross‐sectional analysis, which suggests that some errors are introduced from interpolation of spatially disaggregated simulated variables with a 1D model, instead of model dimensionality 1D or 2D. Flow property differences are larger for velocity than for water surface elevation and depth. Differences in weighted usable area (WUA) derived from 1D and 2D modeling are relatively small for low‐gradient meandering pool–riffle systems, but the differences in the spatial distribution of microhabitats can be considerable although clusters of same habitat quality are spatially comparable. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Improving the computation of the gravitational terrain effect close to ground stations in the GTE software     

Martina Capponi  Ahmed H. Mansi  Daniele Sampietro 《Studia Geophysica et Geodaetica》2018,62(2):206-222

The precise computation of the vertical gravitational attraction of the topographic masses (terrain correction) is still being studied both for geodetic and geophysical applications. In fact, it is essential in high precision geoid estimation by means of the well-known remove-compute-restore technique, which is used to isolate the gravitational effects of anomalous masses in exploration geophysics. The terrain correction can be evaluated exploiting a Digital Terrain Model (DTM) in different ways, such as classical numerical integration, prisms, tesseroids, polyhedrons, and/or Fast Fourier Transform techniques. The increasing resolution of recently developed DTMs, the increasing number of observation points, and the increasing accuracy of gravity data represent, nowadays, major challenges for the terrain correction computation. Classical point mass approximation and prism based-algorithms are indeed too slow, while Fourier-based algorithms are usually too much approximate when compared to the required accuracy. In this work, we improve the Gravity Terrain Effects (GTE) algorithm, the innovative tool that exploits a combined prism-Fast Fourier Transform approach especially developed for airborne gravimetry, to compute the terrain correction on the surface of the DTM (i.e. corresponding to the ground stations and/or its vicinity). This required development of a proper adjustment of the algorithms implemented within the GTE software and also to define and implement a procedure to overcome the problems of the computation of the gravitational effects due to the actual slope of the terrain close to the stations. The latter problem is thoroughly discussed and solved by testing different solutions like concentric cylindrical rings, triangulated polyhedrons, or ultra-high resolution squared prisms. Finally, numerical tests to prove the temporal efficiency and the computational performances of the improved GTE software to compute terrain correction for ground stations are also presented.  相似文献   

Controls of uncertainty in acid rock drainage predictions from waste rock piles examined through Monte-Carlo multicomponent reactive transport     

Pedretti  Daniele  Mayer  K. Ulrich  Beckie  Roger D. 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(1):219-233

Stochastic Environmental Research and Risk Assessment - Heterogeneity in waste rock piles (WRPs) determines uncertainty in acid mine drainage (ARD) predictions from these deposits. Numerical...  相似文献   

Addressing some critical aspects of the BepiColombo MORE relativity experiment     

Giulia Schettino  Daniele Serra  Giacomo Tommei  Andrea Milani 《Celestial Mechanics and Dynamical Astronomy》2018,130(11):72

The Mercury Orbiter Radio science Experiment (MORE) is one of the experiments on-board the ESA/JAXA BepiColombo mission to Mercury, to be launched in October 2018. Thanks to full on-board and on-ground instrumentation performing very precise tracking from the Earth, MORE will have the chance to determine with very high accuracy the Mercury-centric orbit of the spacecraft and the heliocentric orbit of Mercury. This will allow to undertake an accurate test of relativistic theories of gravitation (relativity experiment), which consists in improving the knowledge of some post-Newtonian and related parameters, whose value is predicted by General Relativity. This paper focuses on two critical aspects of the BepiColombo relativity experiment. First of all, we address the delicate issue of determining the orbits of Mercury and the Earth–Moon barycenter at the level of accuracy required by the purposes of the experiment and we discuss a strategy to cure the rank deficiencies that appear in the problem. Secondly, we introduce and discuss the role of the Solar Lense–Thirring effect in the Mercury orbit determination problem and in the relativistic parameters estimation.  相似文献   

3-Dimensional Necklace Flower Constellations     

David Arnas  Daniel Casanova  Eva Tresaco  Daniele Mortari 《Celestial Mechanics and Dynamical Astronomy》2017,129(4):433-448

A new approach in satellite constellation design is presented in this paper, taking as a base the 3D Lattice Flower Constellation Theory and introducing the necklace problem in its formulation. This creates a further generalization of the Flower Constellation Theory, increasing the possibilities of constellation distribution while maintaining the characteristic symmetries of the original theory in the design.  相似文献   

Ecotoxicological and human health risk in a petrochemical district of southern Italy   总被引：2，自引：0，他引：2  

Ausili A  Gabellini M  Cammarata G  Fattorini D  Benedetti M  Pisanelli B  Gorbi S  Regoli F 《Marine environmental research》2008,66(1):215-217

An ecotoxicological investigation has been carried in the petrochemical district of Priolo (Sicily, Italy), one of the largest in Europe. Results indicated a severe mercury contamination in sediments sampled near a chloro-alkali plant. A clear bioavailability of this element was demonstrated in mussels Mytilus galloprovincialis (both native and translocated) and the benthic fish Mullus barbatus, which also exhibited marked genotoxic damages. The elevated mercury concentrations in marine organisms are a serious concern for human health; according to the national average fish consumption, the provisional tolerable weekly intake (PTWI) of Hg would be easily exceeded by at least 4 to 12 fold. Such toxicological risk is of particular importance for pregnant women, being possibly involved in the elevated frequency of neonatal malformations.  相似文献   

Robust optimization for ship conceptual design     

Matteo Diez  Daniele Peri 《Ocean Engineering》2010,37(11-12):966-977

The paper presents an approach for the robust optimization of a bulk carrier conceptual design, subject to uncertain operating and environmental conditions. The uncertainties involved in the optimization process are addressed and a general formulation for robust design is given. Specifically, the uncertainties involved in the decision making process are taken into account by means of their probabilistic distributions. The expected values and the standard deviations of the relevant quantities are assessed and included in the optimization objectives, whereas the constraints are evaluated in the worst case. This leads to a robust design able to keep a good performance in the whole probabilistic operating scenario. A particle swarm optimization algorithm is used for the global minimization process, minimizing the expectation and the standard deviation of the unit transportation cost.  相似文献   

Response time and water origin in a steep nested catchment in the Italian Dolomites          下载免费PDF全文

Daniele Penna  Giulia Zuecco  Stefano Crema  Sebastiano Trevisani  Marco Cavalli  Luisa Pianezzola  Lorenzo Marchi  Marco Borga 《水文研究》2017,31(4):768-782

In this study, we investigate the surface flow time of rise in response to rainfall and snowmelt events at different spatial scales and the main sources originating channel runoff and spring water in a steep nested headwater catchment (Rio Vauz, Italian Dolomites), characterized by a marked elevation gradient. We monitored precipitation at different elevations and measured water stage/streamflow at the outlet of two rocky subcatchments of the same size, representative of the upper part of the catchment dominated by outcropping bedrock, at the outlet of a soil‐mantled and vegetated subcatchment of similar size but different morphology, and at the outlet of the main catchment. Hydrometric data are coupled with stable isotopes and electrical conductivity sampled from different water sources during five years, and used as tracers in end‐member mixing analysis, application of two component mixing models and analysis of the slope of the dual‐isotope regression line. Results reveal that times of rise are slightly shorter for the two rocky subcatchments, particularly for snowmelt and mixed rainfall/snowmelt events, compared to the soil‐mantled catchment and the entire Rio Vauz Catchment. The highly‐variable tracer signature of the different water sources reflects the geomorphological and geological complexity of the study area. The principal end‐members for channel runoff and spring water are identified in rainfall and snowmelt, which are the dominant water sources in the rocky upper part of the study catchment, and soil water and shallow groundwater, which play a relevant role in originating baseflow and spring water in the soil‐mantled and vegetated lower part of the catchment. Particularly, snowmelt contributes up to 64 ± 8% to spring water in the concave upper parts of the catchment and up to 62 ± 11% to channel runoff in the lower part of the catchment. These results offer new experimental evidences on how Dolomitic catchments capture and store rain water and meltwater, releasing it through a complex network of surface and subsurface flow pathways, and allow for the construction of a preliminary conceptual model on water transmission in snowmelt‐dominated catchments featuring marked elevation gradients.  相似文献