Jacobi Dynamics And The N-Body Problem With Variable Masses     

C. M. Giordano  A. R. Plastino 《Celestial Mechanics and Dynamical Astronomy》1999,75(3):165-183

An appropriate generalization of the Jacobi equation of motion for the polar moment of inertia I is considered in order to study the N-body problem with variable masses. Two coupled ordinary differential equations governing the evolution of I and the total energy E are obtained. A regularization scheme for this system of differential equations is provided. We compute some illustrative numerical examples, and discuss an average method for obtaining approximate analytical solutions to this pair of equations. For a particular law of mass loss we also obtain exact analytical solutions. The application of these ideas to other kind of perturbed gravitational N-body systems involving drag forces or a different type of mass variation is also considered. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Facies characteristics and magma–water interaction of the White Trachytic Tuffs (Roccamonfina Volcano, southern Italy)     

Guido Giordano 《Bulletin of Volcanology》1998,60(1):10-26

 The Quaternary White Trachytic Tuffs Formation from Roccamonfina Volcano (southern Italy) comprises four non-welded, trachytic, pyroclastic sequences bounded by paleosols, each of which corresponds to small- to intermediate-volume explosive eruptions from central vents. From oldest to youngest they are: White Trachytic Tuff (WTT) Cupa, WTT Aulpi, WTT S. Clemente, and WTT Galluccio. The WTT Galluccio eruption was the largest and emplaced ∼ 4 km³ of magma. The internal stratigraphy of all four WTT eruptive units is a complex association of fallout, surge, and pyroclastic flow deposits. Each eruptive unit is organized into two facies associations, Facies Association A below Facies Association B. The emplacement of the two facies associations may have been separated by short time breaks allowing for limited reworking and erosion. Facies Association A consists of interbedded fallout deposits, surge deposits, and subordinate ignimbrites. This facies association involved the eruption of the most evolved trachytic magma, and pumice clasts are white and well vesiculated. The grain size coarsens upward in Facies Association A, with upward increases of dune bedform wavelengths and a decrease in the proportion of fine ash. These trends could reflect an increase in eruption column height from the onset of the eruption and possibly also in mass eruption rate. Facies Association B comprises massive ignimbrites that are progressively richer in lithic clast content. This association involved the eruption of more mafic magma, and pumice clasts are gray and poorly vesiculated. Facies Association B is interpreted to record the climax of the eruption. Phreatomagmatic deposits occur at different stratigraphic levels in the four WTT and have different facies characteristics. The deposits reflect the style and degree of magma–water interaction and the local hydrogeology. Very fine-grained, lithic-poor phreatomagmatic surge deposits found at the base of WTT Cupa and WTT Galluccio could record the interaction of the erupting magma with a lake that occupied the Roccamonfina summit depression. Renewed magma–water interaction later in the WTT Galluccio eruption is indicated by fine grained, lithic-bearing phreatomagmatic fall and surge deposits occurring at the top of Facies Association A. They could be interpreted to reflect shifts of the magma fragmentation level to highly transmissive, regional aquifers located beneath the Roccamonfina edifice, possibly heralding a caldera collapse event. Received: 26 August 1996 / Accepted: 27 February 1998  相似文献   

Integration of laser scanning and thermal imaging in monitoring optimization and assessment of rockfall hazard: a case history in the Carnic Alps (Northeastern Italy)     

Giordano Teza  Gianluca Marcato  Alessandro Pasuto  Antonio Galgaro 《Natural Hazards》2015,76(3):1535-1549

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Testing alternative erosivity indices to predict event soil loss from bare plots in Southern Italy     

V. Bagarello  V. Ferro  G. Giordano 《水文研究》2010,24(6):789-797

Methods for predicting unit plot soil loss for the ‘Sparacia’ Sicilian (Southern Italy) site were developed using 316 simultaneous measurements of runoff and soil loss from individual bare plots varying in length from 11 to 44 m. The event unit plot soil loss was directly proportional to an erosivity index equal to (Q_REI₃₀)^1·47, being Q_REI₃₀ the runoff ratio (Q_R) times the single storm erosion index (EI₃₀). The developed relationship represents a modified version of the USLE‐M, and therefore it was named USLE‐MM. By the USLE‐MM, a constant erodibility coefficient was deduced for plots of different lengths, suggesting that in this case the calculated erodibility factor is representative of an intrinsic soil property. Testing the USLE‐M and USLE‐MM schemes for other soils and developing simple procedures for estimating the plot runoff ratio has practical importance to develop a simple method to predict soil loss from bare plots at the erosive event temporal scale. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

A comparison of different indicators of chaos based on the deviation vectors: application to symplectic mappings     

N. P. Maffione  L. A. Darriba  P. M. Cincotta  C. M. Giordano 《Celestial Mechanics and Dynamical Astronomy》2011,111(3):285-307

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Variability of the health effects of crystalline silica: Fe speciation in industrial quartz reagents and suspended dusts—insights from XAS spectroscopy     

Francesco Di Benedetto  Francesco D’Acapito  Fabio Capacci  Gabriele Fornaciai  Massimo Innocenti  Giordano Montegrossi  Werner Oberhauser  Luca A. Pardi  Maurizio Romanelli 《Physics and Chemistry of Minerals》2014,41(3):215-225

We investigated the speciation of Fe in bulk and in suspended respirable quartz dusts coming from ceramic and iron-casting industrial processes via X-ray absorption spectroscopy, with the aim of contributing to a better understanding of the variability of crystalline silica toxicity. Four different bulk industrial quartz powders, nominally pure quartz samples with Fe contents below 200 ppm, and three respirable dusts filters were selected. Fe speciation was determined in all samples through a coupled study of the X-ray absorption near-edge structure and extended X-ray absorption fine structure regions, operating at the Fe–K edge. Fe speciation revealed common features at the beginning of the different production processes, whereas significant differences were observed on both respirable dusts and bulk dusts exiting from the production process. Namely, a common pollution of the raw quartz dusts by elemental Fe was evidenced and attributed to residuals of the industrial production of quartz materials. Moreover, the respirable samples indicated that reactivity occurs after the suspension of the powders in air. The gravitational selection during the particle suspension consistently allowed us to clearly discriminate between suspended and bulk dusts. On the basis of the obtained results, we provide an apparent spectroscopic discrimination between the raw materials used in the considered industrial processes, and those that are effectively inhaled by workers. In particular, an amorphous Fe^III oxide, with an unsaturated coordination sphere, can be related to silica reactivity (and health consequences).  相似文献   

Quantifying Annual Nitrogen Loads to Virginia’s Coastal Lagoons: Sources and Water Quality Response   总被引：3，自引：0，他引：3  

Juliette Christina Poleto Giordano  Mark J. Brush  Iris C. Anderson 《Estuaries and Coasts》2011,34(2):297-309

Coastal lagoons of the Delmarva Peninsula receive varying annual nitrogen loads because of differing land uses. Extensive development and agriculture contribute to elevated nutrient loads in Maryland and Delaware. Agriculture and forests dominate Virginia’s landscape, suggesting these systems receive lower loads. We used a watershed model to achieve three objectives: (1) quantify loads to Virginia lagoons; (2) determine the sources of the loads; and (3) project changes in annual loads under different development scenarios. Model simulations indicated that some Virginia lagoons receive relatively high annual nutrient loads (kg N year⁻¹) due to intensive agriculture and a high watershed/lagoon areal ratio. Model projections also suggested that increased agricultural and residential development in Virginia could lead to annual loads (kg N year⁻¹) typical of impacted Maryland systems. A comparison of Maryland and Virginia water quality responses to nutrient loading suggested that Virginia’s lagoons exhibit a different response to nutrient loading, though the exact mechanism for this difference is unclear.  相似文献   

On Place and Space: Calculating Social and Spatial Networks in the Budapest Ghetto     

Alberto Giordano  Tim Cole 《Transactions in GIS》2011,15(Z1):143-170

When studying spatial patterns, GIScientists often employ distance‐based methods and techniques, such as network analysis. When studying human behavior, however, spatial patterns often emerge that cannot be adequately examined assuming a physical conceptualization of distance. Such patterns emerged during our study of the process of ghettoization of Jews as implemented in Budapest during the course of 1944. As part of an NSF‐sponsored research project on the geography of the Holocaust, we built a Historical GIS of the Budapest Ghetto with the objective of discovering patterns of Jewish concentration and dispersion as well as simulating potential daily spatial interactions between the Jewish and the non‐Jewish population. Spatial analytical techniques allowed us to discover distinct spatial patterns of isolation, interrelation and concentration, but a whole set of patterns appeared that were the opposite of what we expected, and that could only be explained by thinking of distance not in spatial terms but in social ones. In this article we employ social network analysis to examine the geography of oppression in the Budapest ghetto. What jumped out from our study is the interweaving of space and place – intended as a community bounded by social relations and living in a specific time and location.  相似文献   

The flow dynamics of an extremely large volume pyroclastic flow,the 2.08-Ma Cerro Galán Ignimbrite,NW Argentina,and comparison with other flow types     

Ray A. F. Cas  Heather M. N. Wright  Christopher B. Folkes  Chiara Lesti  Massimiliano Porreca  Guido Giordano  Jose G. Viramonte 《Bulletin of Volcanology》2011,73(10):1583-1609

The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km³ dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35–60%), pumice (<10% generally) and lithic-poor (<5% generally) rhyodacitic ignimbrite, lacking a preceding plinian fallout deposit. The CGI is preserved up to 80 km from the structural margins of the caldera, but almost certainly was deposited up to 100 km from the caldera in some places. Only one emplacement unit is preserved in proximal to medial settings and in most distal settings, suggesting constant flow conditions, but where the pyroclastic flow moved into a palaeotopography of substantial valleys and ridges, it interacted with valley walls, resulting in flow instabilities that generated multiple depositional units, often separated by pyroclastic surge deposits. The CGI preserves a widespread sub-horizontal fabric, defined by aligned elongate pumice and lithic clasts, and minerals (e.g. biotite). A sub-horizontal anisotropy of magnetic susceptibility fabric is defined by minute magnetic minerals in all localities where it has been analysed. The CGI is poor in both vent-derived (‘accessory’) lithics and locally derived lithics from the ground surface (‘accidental’) lithics. Locally derived lithics are small (<20 cm) and were not transported far from source points. All data suggest that the pyroclastic flow system producing the CGI was characterised throughout by high sedimentation rates, resulting from high particle concentration and suppressed turbulence at the depositional boundary layer, despite being a low aspect ratio ignimbrite. Based on these features, we question whether high velocity and momentum are necessary to account for extensive flow mobility. It is proposed that the CGI was deposited by a pyroclastic flow system that developed a substantial, high particle concentration granular under-flow, which flowed with suppressed turbulence. High particle concentration and fine-ash content hindered gas loss and maintained flow mobility. In order to explain the contemporaneous maintenance of high particle concentration, high sedimentation rate at the depositional boundary layer and a high level of mobility, it is also proposed that the flow(s) was continuously supplied at a high mass feeding rate. It is also proposed that internal gas pressure within the flow, directed downwards onto the substrate over which the flow was passing, reduced the friction between the flow and the substrate and also enhanced its mobility. The pervasive sub-horizontal fabric of aligned pumice, lithic and even biotite crystals indicates a consistent horizontal shear force existed during transport and deposition in the basal granular flow, consistent with the existence of a laminar, shearing, granular flow regime during the final stages of transport and deposition.  相似文献   

The rheology of crystal-bearing basaltic magmas from Stromboli and Etna   总被引：4，自引：0，他引：4  

A. Vona  C. Romano  D. Giordano 《Geochimica et cosmochimica acta》2011,75(11):3214-3236

Our ability to forecast volcanic hazards at active volcanoes stems from our knowledge of parameters affecting eruption dynamics. Persistent activity displayed by basaltic volcanic systems, such as Etna and Stromboli, is governed mainly by the textural evolution and rheological properties of eruptive products. Here, we investigate the high temperature (1131 °C < T < 1187 °C) rheological behavior and textural evolution of remelted natural basaltic magmas from Stromboli and Etna volcanic systems upon cooling and crystallization at atmospheric conditions. The pure liquid and subliquidus isothermal viscosities are investigated using a concentric cylinder apparatus by varying strain rate applied to the investigated materials. Detailed textural analysis has been performed in order to evaluate the effect of crystal distribution on the rheological evolution of magmas. At subliquidus conditions, the mineralogical assemblage is dominated by the presence of spinel and plagioclase with the occurrence of stable clinopyroxene only at the lowest temperatures (1157 and 1131 °C for the Stromboli and the Etna samples, respectively). The overall crystal fraction (?) varies between 0.06 and 0.27. In the high T regime the viscous response to applied stress and strain rate is strongly affected by the presence of even small amounts of crystals. Large discrepancies between measured and predicted viscosities obtained using the Einstein-Roscoe (ER) equation are also found at low crystal fractions. We find here that, at the investigated conditions, the physical effect caused by the presence of elongated crystals is orders of magnitude higher than that predicted by existing models which only account for spherical particles. It also appears that a weak shear thinning behavior occurs at the lowest temperatures investigated. Crystal shape and, with it, the strain-rate dependence of the rheological properties appear to play primary roles in influencing the transport properties of these basaltic magmas.  相似文献