HYDRO_GEN: A spatially distributed random field generator for correlated properties   总被引：1，自引：0，他引：1  

Alberto Bellin  Yoram Rubin 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(4):253-278

This paper describes a new method for generating spatially-correlated random fields. Such fields are often encountered in hydrology and hydrogeology and in the earth sciences. The method is based on two observations: (i) spatially distributed attributes usually display a stationary correlation structure, and (ii) the screening effect of measurements leads to the sufficiency of a small search neighborhood when it comes to projecting measurements and data in space. The algorithm which was developed based on these principles is called HYDRO_GEN, and its features and properties are discussed in depth. HYDRO_GEN is found to be accurate and extremely fast. It is also versatile: it can simulate fields of different nature, starting from weakly stationary fields with a prescribed covariance and ending with fractal fields. The simulated fields can display statistical isotropy or anisotropy.  相似文献   

Regional structure modelling and source inversion for the 1992 Roermond earthquake     

H. Dufumier  A. Michelini  Z. Du  I. Bondar  J. Sileny  W. Mao  S. Kravanja  G. F. Panza 《Journal of Seismology》1997,1(4):321-340

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Inelastic seismic analysis of a building structure designed by argentine codes     

Victorio E. Sonzogni  Alberto Cardona  Sergio R. Idelsohn 《地震工程与结构动力学》1984,12(6):721-736

A reinforced concrete frame-wall structure of a building designed in accordance to standard practice in Argentina was analysed by the procedures prescribed by current Argentine Codes. In addition, the inelastic step-by-step response of the structure to design spectrum-compatible accelerograms was studied by means of a special element for inelastic dynamic analysis of reinforced concrete frames. Results obtained by the different methods of analysis are presented.  相似文献   

Fluid absent melting of a layered crustal protolith: implications for the generation of anatectic granites     

Kjell P. Skjerlie  Alberto E. Patiño Douce  A. Dana Johnston 《Contributions to Mineralogy and Petrology》1993,114(3):365-378

We report the result of H₂O-undersaturated melting experiments on charges consisting of a layer of powdered sillimanite-bearing metapelite (HQ36) and a layer of powdered tonalitic gneiss (AGC150). Experiments were conducted at 10 kbar at 900°, 925° and 950°C. When run alone, the pelite yielded 40 vol% strongly peraluminous granitic melt at 900°C while the tonalite produced only 5 vol% weakly peraluminous granitic melt. At 950°C, the pelite and the tonalite yielded 50 vol% and 7 vol% granitic melt, respectively. When run side by side, the abundance of melt in the tonalite was 10 times higher at all temperatures than when it was run alone. In the pelite, the melt abundance increased by 25 vol%. When run alone, biotite dehydration-melting in the tonalite yielded orthopyroxene and garnet in addition to granitic melt. When run side by side only garnet was produced in addition to granitic melt. Experiments of relatively short duration, however, also contained Al-rich orthopyroxene. We suggest that the large increase in melt fraction in the tonalite is mainly a result of increased activity of Al₂O₃ in the melt, which lowers the temperature of the biotite dehydration-melting reaction. In the pelite, the increase in the abundance of melt is caused by transport of plagioclase component in the melt from the tonalite-layer to the pelite-layer. This has the effect of changing the bulk composition of this layer in the direction of minimum-temperature granitic liquids. Our results show that rocks which are poor melt-producers on their own can become very fertile if they occur in contact with rocks that contain components that destabilize the hydrous phase(s) and facilitate dehydration-melting. Because of this effect, the continental crust may have an even greater potential for granitoid melt production than previously thought. Our results also suggest that many anatectic granites most likely contain contributions from two or more different source rocks, which will be reflected in their isotopic and geochemical compositions.  相似文献   

Record of recent river channel instability, Cheakamus Valley, British Columbia     

John J. Clague  Robert J. W. Turner  Alberto V. Reyes   《Geomorphology》2003,53(3-4):317-332

Rivers flowing from glacier-clad Quaternary volcanoes in southwestern British Columbia have high sediment loads and anabranching and braided planforms. Their floodplains aggrade in response to recurrent large landslides on the volcanoes and to advance of glaciers during periods of climate cooling. In this paper, we document channel instability and aggradation during the last 200 years in lower Cheakamus River valley. Cheakamus River derives much of its flow and nearly all of its sediment from the Mount Garibaldi massif, which includes a number of volcanic centres dominated by Mount Garibaldi volcano. Stratigraphic analysis and radiocarbon and dendrochronological dating of recent floodplain sediments at North Vancouver Outdoor School in Cheakamus Valley show that Cheakamus River aggraded its floodplain about 1–2 m and buried a valley-floor forest in the early or mid 1800s. The aggradation was probably caused by a large (ca. 15–25×10⁶ m³) landslide from the flank of Mount Garibaldi, 15 km north of our study site, in 1855 or 1856. Examination of historical aerial photographs dating back to 1947 indicates that channel instability triggered by this event persisted until the river was dyked in the late 1950s. Our observations are consistent with data from many other mountain areas that suggest rivers with large, but highly variable sediment loads may rapidly aggrade their floodplains following a large spike in sediment supply. Channel instability may persist for decades to centuries after the triggering event.  相似文献   

Geographic Information Technologies and the History of a Shoreline: The Case of Chapter 91 in New Bedford,Massachusetts*     

Alberto Giordano  Richard Gelpke 《The Professional geographer》2003,55(3):329-342

This article discusses the use of geographic information technologies to assist researchers in the exploration of historical databases. The case study is a pilot project in which we used geographic information systems (GIS) and global positioning systems (GPS) to study the history of the Public Waterfront Act (the “Chapter 91” program), a policy designed to balance private property rights, public interest, and environmental protection in the Massachusetts tidelands. The issues discussed range from the role of GIS in society and its limitations as a representational tool to the ability of current GIS to deal with historical data and to manage temporal attributes.  相似文献   

An Urban Surface Exchange Parameterisation for Mesoscale Models   总被引：9，自引：11，他引：9  

Alberto Martilli  Alain Clappier  Mathias W. Rotach 《Boundary-Layer Meteorology》2002,104(2):261-304

A scheme to represent the impact of urban buildings on airflow in mesoscale atmospheric models is presented. In the scheme, the buildings are not explicitly resolved, but their effects on the grid-averaged variables are parameterised. An urban quarter is characterised by a horizontal building size, a street canyon width and a building density as a function of height. The module computes the impact of the horizontal (roof and canyon floor) and vertical (walls) surfaces on the wind speed, temperature and turbulent kinetic energy. The computation of the shortwave and longwave radiation, needed to compute the temperature of the urban surfaces, takes into account the shadowing and radiation trapping effects induced by the urban canyons. The computation of the turbulent length scales in the TKE equation is also modified to take into account the presence of the buildings.The parameterisation is introduced into a mesoscale model and tested in a bidimensional case of a city over flat terrain. The new parameterisation is shown to be able to reproduce the most important features observed in urban areas better than the traditional approach which is based only on the modification of the roughness length, thereby retaining the Monin–Obukhov similarity theory. The new surface exchange parameterisation is furthermore shown to have a strong impact on the dispersion characteristics of air pollutants in urban areas.  相似文献   

Late Triassic-Early Jurassic Paleokarst from the Ligurian Alps and its geological significance (Siderolitico Auct., Ligurian Briançonnais domain)     

Alessandro Decarlis  Alberto Lualdi 《Swiss Journal of Geoscience》2008,101(3):579-593

In the Ligurian Briançonnais domain, the thick Middle Triassic carbonateplatform units, formally known as the Costa Losera Fm. and S. Pietro dei Monti Dolomites, are followed by a significant unconformity separating them from the Rio di Nava neritic limestones of Bathonian age. According to the evolution of a passive continental margin, the end of subsidence and subsequent uplift led to the progressive erosion of the Triassic carbonate platform from outer to inner units, i.e., in the direction of the Ligurian Tethys. This erosion, possibly acting on a fault-controlled block system, created sedimentary sequences of differential composition, and the virtual absence of the entire Triassic complex and even the underlying Permian rocks. In the study area (and in many other locations belonging to the external Ormea unit), the so-called “briançonnais sedimentary gap” shows more than a nondepositional surface: the associated deposits (known as “Siderolitico” Auct.) include both red pelites between the above-mentioned units, and deep-penetrating karstic red breccia within the Ladinian carbonates. We performed detailed stratigraphic, microfacies and compositional analyses on the karsts and paleosoils associated with the unconformity in order to define their character, genesis and age. In addition, we discuss the regional context and importance of these deposits in a large-scale comparison with the classic Briançonnais domain and other locations of the Western Alpine Arch with the same unconformity. In light of these data, we propose an Upper Triassic to Early Jurassic age (until the Upper Bajocian?) for the karstic event in the Ligurian Alps.  相似文献   

Insights about the formation of a complex impact structure formed in basalt from numerical modeling: The Vista Alegre structure,southern Brazil     

Marcos Alberto Rodrigues Vasconcelos  Fernanda Farias Rocha  Alvaro Penteado Crsta  Kai Wünnemann  Nicole Güldemeister  Emilson Pereira Leite  Júlio Csar Ferreira  Wolf Uwe Reimold 《Meteoritics & planetary science》2019,54(10):2373-2383

We present the outcomes of simulations of the formation of the Vista Alegre impact structure, Paraná Basin, Brazil. The target comprised a thick sequence of volcanic rocks of predominantly basaltic composition of the Serra Geral Formation that had been deposited on top of sedimentary rocks (sandstones) of the Pirambóia/Botucatu formations. The cratering process was modeled using the iSALE shock physics code. Our best‐fit model suggests that (1) the crater was originally ~10 km in size; (2) it was formed in ~115 s by a stony projectile of 1000 m in diameter, for an assumed impact velocity of 12 km s^?1; (3) target rocks underwent a peak pressure of ~20 GPa, in agreement with previous petrographic investigations of shock deformation. Furthermore, the model points out that the sedimentary strata below the layer of volcanic rocks were raised by ~650 meters at the central part of the crater, which resulted in the current partial exposure of the sandstones at the surface. The outcomes of our modeling suggest that parameters like cohesion and strength of the target rocks, after shock compression, determined the final morphology of the crater, especially the absence of a topographically prominent central peak. Finally, the results of the numerical modeling are roughly in agreement with gravity data over the structure, in particular with respect to the presence of the uplifted sedimentary strata, which are responsible for a low gravity signature at the center of the structure.  相似文献   

A systematic analysis of the <Emphasis Type="Italic">XMM-Newton</Emphasis> background: II. Properties of the in-Field-Of-View excess component     

David Salvetti  Martino Marelli  Fabio Gastaldello  Simona Ghizzardi  Silvano Molendi  Andrea De Luca  Alberto Moretti  Mariachiara Rossetti  Andrea Tiengo 《Experimental Astronomy》2017,44(3):309-320

We present an accurate characterization of the particle background behaviour on XMM-Newton based on the entire EPIC archive. This corresponds to the largest EPIC data set ever examined. Our results have been obtained thanks to the collaboration between the FP7 European program EXTraS and the ESA R&D ATHENA activity AREMBES. We used as a diagnostic an improved version of the diagnostic which compares the data collected in unexposed region of the detector with the region of the field of view in the EPIC-MOS. We will show that the in Field-of-View excess background is made up of two different components, one associated to flares produced by soft protons and the other one to a low-intensity background. Its origin needs to be further investigated.  相似文献