Non linear shallow water modelling of bore-driven swash: Description of the bottom boundary layer     

Riccardo Briganti  Nicholas Dodd  Dubravka Pokrajac  Tom O'Donoghue 《Coastal Engineering》2011

The paper presents a simple approach to estimate the bottom shear stress in the swash zone by coupling the Non Linear Shallow Water Equations with the momentum integral equation for the bottom boundary layer. The approach allows not only the computation of the frictional dissipation term in the equations but also to have an insight into the flow structure in the water column during a swash event. The numerical results have been compared with a new set of experiments involving a single dam-break generated swash event. Three different grain sizes, ranging from coarse sand to gravel, have been tested in the laboratory.  相似文献   

Large and small numbers: options for quantifying the costs of extremes on transport now and in 40 years     

Claus Doll  Stefan Klug  Riccardo Enei 《Natural Hazards》2014,72(1):211-239

The past 15 years has been characterized by a high density of record-breaking weather extremes in Europe. These include the extratropical cyclones Lothar, Kyrill and Xynthia across western and mid Europe; the major floods in the UK, Germany and eastern Europe; the heat waves in 2003 and 2007 and, after a long period of mild winters, the heavy winter seasons in 2009/2010 and 2010/2011. Inspired by the rising trends in weather-related damages worldwide and the studies on the topic carried out in overseas, the EC funded the sister projects such as Weather Extremes-Assessing the Impacts on Transport and Hazards for European Regions (WEATHER), EWENT and ECCONET to determine the magnitude of current and future risks to the European transport sector and to assess suitable adaptation strategies. This paper presents the assessment framework of the WEATHER project and the results of weather-inflicted damage costs now and in 2040–2050. Total annual damages are found to be around €2.5 billion, which largely attribute to road traffic. However, broken down to passenger and ton kilometers the highest risk is borne by rail traffic due to its expensive infrastructures and its comparably complex operating structure. This indication even amplifies when looking four decades ahead: while average road transport costs will only raise by 7 % due to milder winters, rail traffic costs may increase by up to 80 % due to more floods and less predictable winter periods. A comparison with the results of the EWENT study uncovers a high range of uncertainty concerning methodological approaches and data treatment. Thus, the final figures might even be much higher.  相似文献   

The Campo Imperatore Near Earth Object Survey (CINEOS)     

Andrea Boattini  Germano D’Abramo  Giovanni B. Valsecchi  Andrea Carusi  Andrea Di Paola  Fabrizio Bernardi  Robert Jedicke  Alan W. Harris  Elisabetta Dotto  Fiore De Luise  Davide Perna  Riccardo Leoni 《Earth, Moon, and Planets》2007,100(3-4):259-271

The Campo Imperatore Near Earth Object Survey (CINEOS) is an Italian survey dedicated to the search and follow-up of Near Earth Objects (NEOs). It is operated with the 90 cm f/3 Schmidt telescope at the Campo Imperatore of the Rome Astronomical Observatory (INAF-OAR) as a joint project with the Istituto di Astrofisica Spaziale and Fisica Cosmica (INAF-IASF) in Rome. Since the end of 2001 CINEOS has covered about 4,250 sq. deg to 20th magnitude in the course of about 160 nights. This effort led to the discovery of 7 Near Earth Asteroids (NEAs), 1 comet (167P/CINEOS; a member of the Centaur group) and a few other unusual objects including 2004 XH₅₀ with a unique comet-like orbit. CINEOS has also contributed almost 2,200 preliminary designations and over 30,000 detections to the Minor Planet Center. About 20% of the survey effort was carried out at low solar elongations (LSE), although no object with an orbit interior (Inner Earth Objects, IEO class) or nearly interior to the Earth (Aten class) was found. The work at LSE was, however, very important to test survey strategies implemented with larger telescopes. We also provide the results of a CINEOS simulation on a reliable NEO population model based on the results of two larger scale surveys, Spacewatch and LINEAR.  相似文献   

Anomalous far‐field geodetic signature related to the 2009 L'Aquila (central Italy) earthquake     

Simone Atzori  Claudio Chiarabba  Roberto Devoti  Manuela Bonano  Riccardo Lanari 《地学学报》2013,25(5):343-351

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Shoreline motion in nonlinear shallow water coastal models     

Riccardo Briganti  Nicholas Dodd 《Coastal Engineering》2009,56(5-6):495-505

Different shoreline boundary conditions for numerical models of the Non-Linear Shallow Water Equations based on Godunov-type schemes are compared. The study focuses on the Peregrine and Williams [Peregrine, D.H., Williams, S.M., 2001. Swash overtopping a truncated plane beach. Journal of Fluid Mechanics 440, 391–399.] problem of a single bore collapsing on a slope. This is considered the best test to assess performances of the shoreline boundary treatments in terms of all the parameters of interest in swash zone modelling. Emphasis is given to the shoreline trajectory and flow velocity modelling. A mismatch of the velocity at the early stage of the motion is highlighted. Most of the tested techniques perform similarly in terms of maximum run-up, the backwash phase is critical in all cases. Starting from the Brocchini et al. [Brocchini, M., Bernetti, R., Mancinelli, A., Albertini, G., 2001. An efficient solver for nearshore flows based on the WAF method. Coastal Engineering 43(2), 105–129.] shoreline boundary treatment, a simple technique that improves the accuracy of velocity predictions is also developed. A sensitivity analysis of the domain resolution and the threshold value of the water depth that defines a wet cell is also presented.  相似文献   

Rare earth elements in groundwater from different Alpine aquifers   总被引：3，自引：0，他引：3  

Riccardo Biddau  Michael Bensimon  Rosa Cidu  Aurele Parriaux 《Chemie der Erde / Geochemistry》2009,69(4):327-339

Rare earth elements (REE) were determined in 39 groundwater samples collected at 14 sites under low- and high-flow conditions. Water samples derived from aquifers hosted in crystalline, molasse, flysch, carbonate and evaporite rocks located in Western Switzerland. The concentration of REE in groundwater circulating in different rocks showed large variations: lowest concentrations (ΣREE≤10 ng/L) occurred in groundwater from evaporite aquifers; highest concentrations (ΣREE up to 516 ng/L) were observed in carbonate aquifers, although REE in these waters do vary under different hydrological conditions; groundwater from other aquifers had ΣREE from 10 to 100 ng/L. Distinct REE signatures were observed in waters draining specific rocks. The REE patterns in groundwater from crystalline, molasse and flysch aquifers showed heavy-REE enrichment at different degrees. Groundwaters circulating in crystalline rocks were distinguished by negative anomalies in Ce and Eu, whereas those from carbonate aquifers were nearly flat with ΣREE and the magnitude of negative anomaly in Ce is likely to be controlled by iron concentrations. The REE-Post-Archean Australian Shales (PAAS) normalized patterns appear useful to recognize the aquifer type and suggest the possibility to use the REE as geochemical tracers.  相似文献   

History of X-ray telescopes and astronomy     

Riccardo Giacconi 《Experimental Astronomy》2009,25(1-3):143-156

The development of X-ray telescopes over the last 45 years is briefly summarized. The first applications to the study of solar X-ray emission are described up to the 1973 Skylab mission. The rather convoluted path that led to the first stellar X-ray orbiting telescope Einstein (1978) and later to Chandra (1999) are discussed. During this 45 years period the angular resolution improved from 20 to 0.5 arc sec and the sensitivity by ten billions. X-ray observations have discovered new types of stellar systems (binary X-ray sources containing neutron stars and black holes) and intergalactic high temperature plasmas containing most of the baryonic mass of the universe. They have become an indispensable tool to study the role of energetic phenomena in the creation and dynamic evolution of cosmic structures. The methodology introduced by X-ray astronomy has influenced all of astronomy.  相似文献   

Zircon U–Pb geochronology of lower crust and quartzo-feldspathic clastic sediments from the Balagne ophiolite (Corsica)     

Maria Rosaria Renna  Riccardo Tribuzio  Alessio Sanfilippo  Massimo Tiepolo 《Swiss Journal of Geoscience》2017,110(2):479-501

The Balagne ophiolite from central-northern Corsica represents a continent-near paleogeographic domain of the Jurassic Liguria-Piedmont ophiolitic basin. Pillow and massive basalt lavas are primarily associated with Middle–Upper Jurassic pelagic sediments (mostly radiolarites at their base), continental-derived quartzo-feldspathic clastic sediments and ophiolitic breccias containing clasts of gabbros and basalts. The basalt-sedimentary succession is tectonically associated with a slice composed of an intrusive sequence overlain by basalt lavas. A “plagiogranite” from the intrusive sequence was dated by U–Pb zircon geochronology. Although affected by some uncertainty, mainly reflecting common Pb contamination, the U–Pb zircon data suggest a crystallization age of 159 ± 3 Ma (MSWD = 6.3), which is coeval with the formation of oceanic lower crust in the Schistes Lustrés units from Alpine Corsica. The predominance of quartz grains preserving typical volcanic shape, the prevalence of prismatic zircons and the arkose whole-rock composition indicate that the continental-derived quartzo-feldspathic clastic sediments have a low degree of textural maturity. U–Pb zircon geochronology carried out on two distinct levels of quartzo-feldspathic clastic sediments identified the predominance of zircons with within error U–Pb dates at ~280 Ma; minor components at ~457, ~309 and ~262 Ma were also obtained. The U–Pb date distribution is consistent with a source magmatic material mostly developed during the Variscan orogenic collapse.  相似文献   

A new simple approach to evaluate pedogenic clay transformation in a Vertic Calcisol     

Claudio Territo  Philippe Vieillard  Dominique Righi  Sabine Petit  Riccardo Scalenghe 《Journal of Geochemical Exploration》2006,88(1-3):345

The aim of this study is to characterize the pedogenic clay minerals by using simple approach: mixing mineralogical and geochemical findings.The fine clay fractions (< 0.1 μm) of a Vertic Cambisol profile were studied by means of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and cation exchange capacity (CEC).Qualitative and quantitative mineralogical compositions of the clay mixture were determined.Moreover, chemical equilibria and thermodynamic stabilities of minerals (calcite, gypsum, kaolinite, smectites and illites) were studied using results of ionic activities obtained from total concentration of various aqueous species in water extracts from soil-saturated pastes.XRD analysis shows a good homogeneity in the mineralogical composition of the soil material, with depth of soil profiles. The identified clay minerals are mainly illite–smectite mixed layers (I/S) and kaolinite. The chemical analysis of saturated paste extracts with clay minerals shows a slight undersaturation of the illitic phase while smectites and also calcite and gypsum reach the thermodynamic equilibrium along the soil profile.  相似文献   

Coseismic rotation changes from the 2004 Sumatra earthquake: the effects of Earth's compressibility versus earthquake induced topography     

Roberto Sabadini  Riccardo E. M. Riva  Giorgio Dalla Via 《Geophysical Journal International》2007,171(1):231-243

Polar motion is modelled for the large 2004 Sumatra earthquake via dislocation theory for an incompressible elastic earth model, where inertia perturbations are due to earthquake-triggered topography of density–contrast interfaces, and for a compressible model, where inertia perturbation due to compression-dilatation of Earth's material is included; density and elastic parameters are based on a multilayered reference Earth. Both models are based on analytical Green's functions, propagated from the centre to the Earth's surface. Preliminary and updated seismological solutions are considered in elucidating the effects of improving earthquake parameters on polar motion. The large Sumatra thrust earthquake was particularly efficient in driving polar motion since it was responsible for large material displacements occurring orthogonally to the strike of the earthquake and to the Earth's surface, as imaged by GRACE gravity anomalies over the earthquake area. The effects of earthquake-induced topography are four times larger than the effects of Earth's compressibility, for l = 2 geopotential components. For varying compressional Earth properties and seismic solution, modelled polar motion ranges from 8.6 to 9.4 cm in amplitude and between 117° and 130° east longitude in direction. The close relationship between polar motion direction, earthquake longitude and thrust nature of the event, are established in terms of basic physical concepts.  相似文献