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51.
Gravitational wave detection through microlensing? 总被引:1,自引:0,他引:1
Roberto Ragazzoni Gianpaolo Valente Enrico Marchetti 《Monthly notices of the Royal Astronomical Society》2003,345(1):100-110
It is shown that accurate photometric observations of a relatively high-magnification microlensing event ( A ≫ 1) , occurring close to the line of sight of a gravitational wave (GW) source, represented by a binary star, can allow the detection of subtle gravitational effects. After reviewing the physical nature of such effects, it is discussed to what extent these phenomena can actually be caused by GWs. Expressions for the amplitude of the phenomena and the detection probability are supplied. 相似文献
52.
V. R. Eke Carlos S. Frenk Carlton M. Baugh Shaun Cole Peder Norberg John A. Peacock Ivan K. Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Gavin Dalton Roberto de Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole A. Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve J. Maddox Darren Madgwick Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2004,355(3):769-784
53.
Antonio Olita Alberto Ribotti Roberto Sorgente Leopoldo Fazioli Angelo Perilli 《Ocean Dynamics》2011,61(1):89-102
Data reduction and signal decomposition techniques have been applied to a large bio-physical remotely sensed dataset covering the decade 1997–2007. The aim was the estimation of the spatial (basin and sub-basin scales) and temporal (seasonal and interannual) variability of sea level anomalies and chlorophyll-a concentration in the Algero-Provençal Basin, as well as the study of their covariability. Empirical orthogonal functions, wavelet analysis, singular value decomposition and correlation maps have been successfully used to individuate the patterns of (co)variability of the investigated fields. The seasonal variability of the phytoplanktonic biomass is divided in two distinct modes, timewise and spacewise separated. Positive interannual events are related to anomalies in 1999 and 2005, while the main (negative) anomaly is that of summer 2003, associated to the European 2003 heatwave. The analysis of the sea level anomalies shows a minimum in the formation of anticyclonic Algerian eddies during that period. The largest anticorrelation between sea level anomalies and phytoplanktonic biomass is found in the central zone of the basin, suggesting a clear biological response to the shoaling/deepening of the isopycnae and so to the nutrient injection into the euphotic layer. The analysis suggests that the driver of the variability of the nutricline depth in this central area is the displacement (seasonal) of the North Balearic Front and the formation/action of the frontal eddies. 相似文献
54.
Predictions from dynamic modelling of the lithospheric deformation are presented for Northern Europe, where several basins underwent inversion during the Late Cretaceous and Early Cenozoic and contemporary uplift and erosion of sediments occurred. In order to analyse the evolution of the continental lithosphere, the equations for the deformation of a continuum are solved numerically under thin sheet assumption for the lithosphere. The most important stress sources are assumed to be the Late Cretaceous Alpine tectonics; localized rheological heterogeneities can also affect local deformation and stress patterns. Present-day observations available in the studied region and coming from seismic structural interpretations and stress measurements have been used to constrain the model. Our modelling results show that lateral variation in lithospheric strength below the basin systems in Central Europe strongly controls the regional deformation and the stress regime. Furthermore, we have demonstrated that the geometry of the boundary between Baltica and Avalonia, together with different rheological characteristics of the two plates, had a crucial role on local crustal deformation and faulting regime resulting in the Baltica–Avalonia transition zone from the S–N Alpine convergence. 相似文献
55.
Xiangyang Zheng Roberto Mayerle Qianguo Xing José Manuel Fernández Jaramillo 《Ocean Dynamics》2016,66(8):1037-1050
In this paper, a data assimilation scheme based on the adjoint free Four-Dimensional Variational(4DVar) method is applied to an existing storm surge model of the German North Sea. To avoid the need of an adjoint model, an ensemble-like method to explicitly represent the linear tangent equation is adopted. Results of twin experiments have shown that the method is able to recover the contaminated low dimension model parameters to their true values. The data assimilation scheme was applied to a severe storm surge event which occurred in the North Sea in December 5, 2013. By adjusting wind drag coefficient, the predictive ability of the model increased significantly. Preliminary experiments have shown that an increase in the predictive ability is attained by narrowing the data assimilation time window. 相似文献
56.
Prof. Dr. Roberto Malaroda 《International Journal of Earth Sciences》1964,53(1):41-57
Riassunto Nell'Autoctono sedimentario delle Alpi Marittime è stata individuata una formazione tipica, sfuggita agli autori precedenti benchè molto caratteristica ed abbastanza estesa. Si tratta perloppiù di calcari, più o meno arenacei, che contengono ciottoli di porfido quarzifero, di rocce migmatiche e di rocce sedimentarie. Ciò porta a modificare lo schema paleogeografico tradizionale ammettendo una emersione del nucleo del Massiccio dell'Argentera nel Cretaceo superiore.
In the autochtonous sedimentary beds of Alpi Marittime a typical formation is found; it is very peculiar and extends over a wide area, but until now it was unknown. The most common lithotypes represented in it are limestones with variable amounts of arenaceous material and containing pebbles of rhyolites and of migmatitic and sedimentary rocks. From these rock types a new paleogeographic scheme is strongly suggested, one in which there was the emersion of the central Argentera Massif during the late Cretaceous time.
Zusammenfassung In den autochthonen sedimentären Einheiten der Meeralpen wurde eine typische Formation entdeckt, die bis jetzt von früheren Verfassern vernachlässigt wurde. Es handelt sich meistens um mehr oder weniger sandige Kalke, die Gerölle von Quarzporphyren und von migmatischen und sedimentären Gesteinen enthalten. Das führt dazu, das bisherige paläogeographische Bild durch das Auftauchen des Kerns vom Argentera-Massiv in der Oberen Kreide abzuändern.
Résumé Dans l'Autochtone sédimentaire des Alpes-Maritimes a été découverte une formation typique, qui a échappé aux auteurs précédents, quoique étant bien caractéristique et suffisamment répandue. Il s'agit normalement de calcaires, plus ou moins gréseux, qui contiennent des galets de rhyolites, de roches migmatiques et de. roches sédimentaires. Cela conduit à modifier le schéma paléogéographique traditionnel en reconnaissant une émersion du noyau du Massif de l'Argentera dans le Crétacé supérieur.
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57.
Roberto Torra 《中国地球化学学报》2004,23(3):220-237
Littoral siliciclastic shallow marine horizontal conformable beds (a heterolithic succession), Middle to Late Miocene, outcropping
in northeastern Argentina (Ituzaingó Formation) and overlying transitional conformable horizontal regolithic mantle-rock bed
derived from them (the Pampean and Post-Pampean Formations), were geochemically analyzed. The focus of this study is placed
on the application of geochemical parameter and signature analyses related with the aforementioned geological units, which
are of subcontinental extension into South America. The encountered results show an outstandingly similar geochemical behaviour
between them. The main conclusion is that regolithic mantle-rock beds were derived from the littoral shallow marine mudstone
(silty-argillaceous) beds. This is in oposition to previous aeolian processes proposed early in the 50’s and later. These
mudstone beds constitute important sections of the littoral shallow marine sequence beds (outcropping HST parasequence). Such
regolitization proposed for the Pampean and Post-Pampean Formations predominantly developed in-situ during the Late Pleistocene
and Holocene. The main erosional and mobilized agents were the surface free water (pluvial, fluvial and laminar water sheets)
and vadose water. So, the wind flows and/or the immense air flow hurricanes are of insignificant sedimentological influence.
Otherwise, there is not a proved appropiate sandy-silty reservoir for a reasonable support of the “aeolian hypothesis”, as
well as clear aeolian structures settled in the regolithic mantle-rock bed. In spite of these lines of equality textural-structural
evidence, the geochemical values for both major elements and trace elements, demonstrate that the Miocene heterolithic marine
succession was the mother rock of the overlying regolithic mantle-rock bed, which was formed as an in-situ mantle-rock bed. 相似文献
58.
Is compression across the northern Apennine fold‐and‐thrust system (Italy) still active? To address this question, we quantified the long‐term rates of migration and shortening of the system along with the measurement errors. Our approach integrates structural geology, seismicity patterns, and statistical treatment of tectonic activity. On the basis of recently published surface and subsurface data, we found a migration rate of 8.85 ± 0.61 mm yr−1. The inception age of individual fold structures follow closely this average rate, indicating that the system has been migrating at a constant rate for the past 17 Myr. Cumulative shortening of the system also increases linearly through time at 2.93 ± 0.31 mm yr−1. The location of the youngest structures in the easternmost portion of the system coincides with a significant peak of seismic moment released by historical earthquakes. We conclude that not only these easternmost thrusts are still active, but also that they generate earthquakes. 相似文献
59.
A structural and geophysical approach to the study of fractured aquifers in the Scansano-Magliano in Toscana Ridge, southern Tuscany, Italy 总被引:1,自引:0,他引:1
Roberto Francese Francesco Mazzarini Andrea Bistacchi Gianfranco Morelli Giorgio Pasquarè Nicola Praticelli Henry Robain Nigel Wardell Annalisa Zaja 《Hydrogeology Journal》2009,17(5):1233-1246
Fresh water availability has recently become a serious concern in the Italian Apennines, as various activities rely on a predictable supply. Along the ridge between Scansano and Magliano in Toscana, in southern Tuscany, the situation is further complicated by contamination of the nearby alluvial aquifers. Aquifers locally consist of thin fractured reservoirs, generally within low-permeability formations, and it can be difficult to plan the exploitation of resources based on conventional techniques. An integrated study based on geological data investigated the link between tectonics and groundwater circulation, to better define the hydrological model. After the regional identification of fault and fracture patterns, a major structure was investigated in detail to accurately map its spatial position and to understand the geometry and properties of the associated aquifer and assess its exploitation potential. The subsurface around the fault zone was clearly imaged using ground probing radar, two-dimensional and three-dimensional resistivity tomography, and three-dimensional shallow seismic surveys. The vertical and horizontal contacts between the different geological units of the Ligurian and Tuscan series were resolved with a high degree of spatial accuracy. Three-dimensional high-resolution geophysical imaging proved to be a very effective means of characterising small-scale fractured reservoirs. 相似文献
60.
The paper presents a strainhardening constitutive model for unsaturated soil behaviour based on energy conjugated stress variables in the framework of superposed continua. The proposed constitutive law deals with hydro‐mechanical coupling phenomena. The main purpose is to develop within a consistent framework a model that can deal with possible mechanical instabilities occurring in partially saturated materials. The loss of capillary effects during wetting processes can, in fact, play a central role in unstable processes. Therefore, it will be shown that the bonding effects due to surface tensions can be described in a mathematical framework similar to that employed for bonded geomaterials to model weathering or diagenesis effects, either mechanically or chemically induced. The results of several simulations of common laboratory tests on partially saturated soil specimens are shown. The calculated behaviour appears to be in good qualitative agreement with that observed in the laboratory. In particular it is shown that volumetric collapse phenomena due to hydraulic debonding effects can be successfully described by the model. Finally, it will be highlighted the ability of the model to naturally capture the transition to a fully saturated condition and to deal with possible mechanical instabilities in the unsaturated regime. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献