Artificial intelligence for the EChO mission planning tool     

Alvaro Garcia-Piquer  Ignasi Ribas  Josep Colomé 《Experimental Astronomy》2015,40(2-3):671-694

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An efficient representation of quadtrees and bintrees for multiresolution terrain models     

Yusnier Valle  José Ortiz 《地球空间信息科学学报》2011,14(3):198-206

A space-filling curve in 2,3,or higher dimensions can be thought as a path of a continuously moving point.As its main goal is to preserve spatial proximity,this type of curves has been widely used in the design and implementation of spatial data structures and nearest neighbor-finding techniques.This paper is essentially focused on the efficient representation of Digital Ele-vation Models(DEM) that entirely fit into the main memory.We propose a new hierarchical quadtree-like data structure to be built over domains of unrestricted size,and a representation of a quadtree and a binary triangles tree by means of the Hilbert and the Sierpinski space-filling curves,respectively,taking into account the hierarchical nature and the clustering properties of this kind of curves.Some triangulation schemes are described for the space-filling-curves-based approaches to efficiently visualize multiresolu-tion surfaces.  相似文献   

Local and remote responses to opposite Ross Sea ice anomalies: a numerical experiment with the CPTEC/INPE AGCM     

Christopher A. Cunningham  Jos�� Paulo Bonatti 《Theoretical and Applied Climatology》2011,106(1-2):23-44

This work examines the near-surface responses, in the Southern Hemisphere atmosphere, to a reduction and an excess of sea ice cover in the Ross Sea. Large ensembles (60 members) of the Atmospheric General Circulation Model of the Center for Weather Forecast and Climate Studies (AGCM-CPTEC) are used for this purpose. Locally, when the sea ice cover decreases (increases), heat fluxes, temperature, and pressure increase (decreases). A principal component analysis of temperature and geopotential height identifies the potential remote connections. We have found three main results: first, an association between the sea ice cover in the Ross Sea and a wave train that resembles the Pacific South American (PSA) pattern; second, a relationship between temperatures in the Ross Sea and in the southern South America; and third, an apparent correspondence between reduced sea ice cover in the Ross Sea and the subtropical jet over Australia.  相似文献   

Modeling fecal contamination in the Aljezur coastal stream (Portugal)   总被引：1，自引：1，他引：0  

Marta Rodrigues  Anabela Oliveira  Martha Guerreiro  André Bustorff Fortunato  José Menaia  Luís Mesquita David  Alexandra Cravo 《Ocean Dynamics》2011,61(6):841-856

This study aims at understanding the fecal contamination behavior in a small coastal stream (Aljezur, Portugal), which has significant economic and ecological values. Like in most small coastal systems, circulation and water renewal in the Aljezur stream exhibit a strong variability due to their dependence on tides, waves, intermittent river flows, and a highly variable morphology. Hence, the problem was approached through a combination of field surveys and the development and application of a hard-coupled three-dimensional hydrodynamic and fecal contamination model. Salinity and temperature results have shown that mixing and transport in the stream are very sensitive to the river flow and wind forcing. The model is able to represent the main patterns and trends observed in Escherichia coli and fecal enterococcus concentrations along the stream, for different environmental and contamination conditions, suggesting die-off rates on the order of 0.50–0.55 day⁻¹. Die-off rate and the representation of the sediment-associated processes were identified as the major remaining sources of uncertainty in the model. Results show that, owing to the processes that occur along the stream, fecal bacteria reach the beaches water in numbers that comply with the European Bathing Waters Directive, even during the summer periods when the upstream concentrations are larger. In particular, results suggest a direct relation between the tidal propagation upstream and the reduction of the fecal bacteria concentrations along the stream that can be relevant for the development of a strategy for the management of the system’s water safety.  相似文献   

P–T-Fluid evolution and graphite deposition during retrograde metamorphism in Ribeira Fold Belt,SE Brazil: Oxygen fugacity,fluid inclusions and C–O–H isotopic evidence     

Telmo M. Bento dos Santos  José M.U. Munhá  Colombo C.G. Tassinari  Fernando M. Noronha  Alexandra Guedes  Paulo E. Fonseca  Coriolano Dias Neto  Armanda Dória 《Journal of South American Earth Sciences》2011,31(1):93-109

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High-pressure displacive phase transition of a natural Mg-rich pigeonite     

Matteo Alvaro  Fabrizio Nestola  Fernando Cámara  M. Chiara Domeneghetti  Vittorio Tazzoli 《Physics and Chemistry of Minerals》2011,38(5):379-385

A high-pressure single-crystal X-ray diffraction study has been carried out on a P2₁/c natural Mg-rich pigeonite sample with composition ca. Wo₆En₇₆Fs₁₈ using a diamond anvil-cell. The unit-cell parameters were determined at 14 different pressures to 7.14 GPa. The sudden disappearance of the b-type reflections (h + k = odd) and a strong discontinuity (about 2.8%) in the unit-cell volume indicated a first-order P2₁/c–C2/c phase transition between 4.66 and 4.88 GPa. The P(V) data of the P2₁/c phase were fitted to 4.66 GPa by a third-order Birch–Murnaghan equation of state (BM3 EoS), whereas the limited number of experimental data collected within the C2/c phase between 4.88 and 7.14 GPa were fitted using the same equation of state but with K′ constrained to the value obtained for the P2₁/c fitting. The equation of state coefficients are V ₀ = 424.66(6) ų, K _T0 = 104(2) GPa and K′ = 8(1) for the P2₁/c phase, and V ₀ = 423.6(1) ų, K _T0 = 112.4(8) GPa, and K′ fixed to 8(1) for the C2/c phase. The axial moduli for a, b, and c for the P2₁/c phase were obtained using also a BM3-EoS, while for the C2/c phase only a linear calculation could be performed, and therefore the same approach was applied for comparison also to the P2₁/c phase. In general the C2/c phase exhibits axial compressibilities (β _c > β _a >> β _b) lower than those of the P2₁/c phase (β _b > β _c ≈ β _a; similar to those found in previous studies in clinopyroxenes and orthopyroxenes). The lower compressibility of the C2/c phase compared with that of the P2₁/c could be ascribed to the greater stiffness along the b direction. A previously published relationship between P _c and M2 average cation radius (i.r.) has been updated using all the literature data on P2₁/c clinopyroxene containing large cations at M2 site and our new data. The following weighted regression was obtained: P _c (GPa) = 26(4) ? 28(5) ×  i.r (Å), R ² = 0.97. This improved equation can be used to predict the critical pressure of natural P2₁/c clinopyroxene samples just knowing the composition at M2 site.  相似文献   

Applicability of Newmark method at regional, sub-regional and site scales: seismically induced Bullas and La Paca rock-slide cases (Murcia, SE Spain)     

Martín Jesús Rodríguez-Peces  José Luis Pérez-García  Julián García-Mayordomo  José Miguel Aza?ón  Juan Miguel Insua-Arévalo  Jorge Delgado-García 《Natural Hazards》2011,59(2):1109-1124

In this paper, the applicability of the Newmark method at regional, sub-regional and site scales has been investigated in the Lorca Basin (Murcia). This basin is located in one of the most seismically active regions of Spain. The area is very interesting for studying earthquake-induced slope instabilities as there are well-known cases associated with specific earthquakes. For the regional and sub-regional scales, a geographic information system has been used to develop an implementation of Newmark sliding rigid block method. Soil and topographic amplification effects have been particularly considered. Subsequently, ‘Newmark displacement’ maps for deterministic seismic scenarios have been produced. Some specific studies have also been performed using limit equilibrium methods to estimate the safety factor and the critical acceleration of certain slope instabilities at a site scale. These instabilities were the rock slides related to recent seismic series at the Lorca Basin: 2002 Bullas (M _w = 5.0) and 2005 La Paca (M _w = 4.8). Finally, the safety factor, critical acceleration and Newmark displacement values estimated at different scales have been compared to determine which scale is most suitable for the Newmark method.  相似文献   

Defining the dynamics of groundwater in Serra da Estrela Mountain area, central Portugal: an isotopic and hydrogeochemical approach     

Paula M. Carreira  Jos�� M. Marques  Jorge Espinha Marques  Helder I. Chamin��  Paulo E. Fonseca  Fernando Monteiro Santos  Rui M. Moura  Jos�� M. Carvalho 《Hydrogeology Journal》2011,19(1):117-131

In a multidisciplinary approach, geological, geomorphologic, structural, hydrogeochemical and isotopic surveys were conducted on the Serra da Estrela groundwater system (central Portugal) in order to establish/develop a conceptual circulation model of the Caldas de Manteigas thermomineral system. A detailed study of the isotopic and geochemical composition of surface waters (e.g. Zêzere River), shallow groundwaters (cold dilute springs), and thermomineral waters was carried out to characterize the distribution of isotopes in waters of this mountainous region, and to determine the origin and possible recharge locations of the thermomineral system. Special attention was dedicated to isotopic tracers and their role in the definition of the thermomineral waters??conceptual model, considering: (1) the δ¹⁸O fractionation gradient; (2) the mean isotopic composition of the thermomineral waters in the region; and (3) the estimation of snowmelt contribution as a source of groundwater recharge at Serra da Estrela. The recharge of the thermomineral aquifer takes place on the more permeable zones of the granitic massif, associated with the main tectonic structures, whereas the recharge of the shallow aquifers seems to take place mostly in the plateaus, although another part of the recharge may occur in the slopes of the Zêzere River valley.  相似文献   

New palaeontological investigations in the Jurassic of western Thailand     

Takeshi Kozai  Lydia Perelis-Grossowicz  Annachiara Bartolini  Chotima Yamee  José Sandoval  Francis Hirsch  Keisuke Ishida  Thasinee Charoentitirat  Assanee Meesook  Jean Guex 《Gondwana Research》2011,19(1):37-46

The paleontological investigations of the Jurassic of Western Thailand, districts of Mae Sot (Tak–Mae Sot highway, Padaeng Tak and Ban Mae Kut Luang Zinc mines) and Umphang (Klo Tho), provide age constraints for the Late Indosinian orogeny, the Paleotethys closure and the timing of the marine Jurassic inundation of Sundaland. The basal conglomerate of the Jurassic is derived from the pelagic Triassic Mae Sariang substratum. Stratigraphy, microfacies and paleontology of the Jurassic marine strata focus especially on ammonites, bivalves, large benthic foraminifera and algae. Among ammonites, the Tethyan Catulloceras perisphinctoides Gemmellaro marks the Upper Toarcian (Aalensis Zone) along the Tak–Mae Sot highway and Riccardiceras longalvum (Vacek), Malladaites pertinax (Vacek), Abbasites sp. and Vacekia sp. indicate Middle Aalenian to lowermost Bajocian in the Padaeng Mine (SE of Mae Sot) and Klo–Tho (Umphang). Vacekia sp., Spinammatoceras schindewolfi Linares and Sandoval and Malladaites vaceki Linares and Sandoval indicate Middle Aalenian to lowermost Upper Aalenian at Ban Mae Kut Luang (NE of Mae Sot). Among foraminifers, the large benthic foraminifer Timidonella sarda Bassoullet, Chabrier and Fourcade in the Western Tethys is indicative for Aalenian–Bajocian times, as characterized in the section at the Tak–Padaeng Zinc mine and the Klo–Tho Formation near Umphang. The endemic foraminifer Gutnicella kaempferi characterizes the Pu Khloe Khi Formation near Umphang. Among bivalves, shallow marine, dominantly endemic fauna includes Parvamussium donaiense (Mansuy) and Bositra ornate (Quenstedt), from the Toarcian to the Early Bajocian. A consideration of the faunal affinity shows that the fauna is partly endemic with Northern Tethyan (Eurasian) affinity.  相似文献   

Criteria for recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic,fluid inclusion,and isotopic analysis of the Tera Group,Northern Spain     

Laura González-Acebrón  R. H. Goldstein  Ramón Mas  José Arribas 《International Journal of Earth Sciences》2011,100(8):1811-1826

Stratigraphic relations, detailed petrography, microthermometry of fluid inclusions, and fine-scale isotopic analysis of diagenetic phases indicate a complex thermal history in Tithonian fluvial sandstones and lacustrine limestones of the Tera Group (North Spain). Two different thermal events have been recognized and characterized, which are likely associated with hydrothermal events that affected the Cameros Basin during the mid-Cretaceous and the Eocene. Multiple stages of quartz cementation were identified using scanning electron microscope cathodoluminescence on sandstones and fracture fills. Primary fluid inclusions reveal homogenization temperatures (Th) from 195 to 350°C in the quartz cements of extensional fracture fillings. The high variability of Th data in each particular fluid inclusion assemblage is related to natural reequilibration of the fluid inclusions, probably due to Cretaceous hydrothermal metamorphism. Some secondary fluid inclusion assemblages show very consistent data (Th = 281–305°C) and are considered not to have reequilibrated. They are likely related to an Eocene hydrothermal event or to a retrograde stage of the Cretaceous hydrothermalism. This approach shows how multiple thermal events can be discriminated. A very steep thermal gradient of 97–214°C/km can be deduced from δ¹⁸O values of ferroan calcites (δ¹⁸O −14.2/−11.8‰ V-PDB) that postdate quartz cements in fracture fillings. Furthermore, illite crystallinity data (anchizone–epizone boundary) are out of equilibrium with high fluid inclusion Th. These observations are consistent with heat-flux related to short-lived events of hydrothermal alteration focused by permeability contrasts, rather than to regional heat-flux associated with dynamo-thermal metamorphism. These results illustrate how thermal data from fracture systems can yield thermal histories markedly different from host-rock values, a finding indicative of hydrothermal fluid flow.  相似文献