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581.
Vania Bogorny Hercules Avancini Bruno Cesar de Paula Cassiano Rocha Kuplich Luis Otavio Alvares 《Transactions in GIS》2011,15(2):227-248
Enormous quantities of trajectory data are collected from many sources, such as GPS devices and mobile phones, as sequences of spatio‐temporal points. These data can be used in many application domains such as traffic management, urban planning, tourism, bird migration, and so on. Raw trajectory data, as generated by mobile devices have very little or no semantics, and in most applications a higher level of abstraction is needed to exploit these data for decision making. Although several different methods have been proposed so far for trajectory querying and mining, there are no software tools to help the end user with semantic trajectory data analysis. In this article we present a software architecture for semantic trajectory data mining as well as the first software prototype to enrich trajectory data with both semantic information and data mining. As a prototype we extend the Weka data mining toolkit with the module Weka‐STPM, which is interoperable with databases constructed under OGC specifications. We tested Weka‐STPM with real geographic databases, and trajectory data stored under the Postgresql/PostGIS DBMS. 相似文献
582.
583.
In Europe, the number of establishment of non-native species, especially from Ponto-Caspian area, has dramatically increased over the past decades and induced important changes in macroinvertebrate assemblages, mainly in large rivers. However, although many Ponto-Caspian species were established in adjacent countries, only two Ponto-Caspian amphipods were formally observed in French hydrosystems since 1996. To update our knowledge on the present distribution of the Ponto-Caspian species in France, we collected amphipods from 203 sites in the Rhine, Meuse and Seine River basins in 2008 and again in 2009. Thirteen amphipod species were found in the study area. Among them, four were first formally recorded in France (Dikerogammarus haemobaphes, Dikerogammarus bispinosus, Echinogammarus ischnus, and Echinogammarus trichiatus). Our study revealed three different corridors used by these species to arrive in France. We also observed a different pattern of colonization for each species, which might indicate some between-species differences in their preferences for environmental conditions. The snapshot of the early distributions of these recently established species may hence be used to study the invasion pattern in France in order to manage their potential impact in and outside France. 相似文献
584.
Fidel GrandiaClara Sena David ArcosJorge Molinero Lara DuroJordi Bruno 《Applied Geochemistry》2011,26(5):679-687
The Quaternary sediments representing the interface between the granite host rock and the Earth surface are of paramount importance when determining the potential cycling of anthropogenic and natural radionuclides in near-surface systems. This is particularly true in the case of high-level nuclear waste (HLNW) repositories placed in granite. In this work a modelling procedure is presented to quantitatively determine the retention capacity of a Quaternary till in the Forsmark area, which has been recently selected to host the deep geologic storage of HLNW in Sweden. Reactive transport numerical models have been used to simulate the intrusion of a deep groundwater carrying radionuclides potentially released from a repository into a Quaternary till. Four radionuclides (235U, 135Cs, 226Ra and 90Sr) have been selected according to their different geochemical behaviour and potential dose relevance to surface ecosystems. Numerical results indicate that repository-derived: (i) U will have a minor impact in the till, mainly due to the high natural concentration of U and its adsorption on ferrihydrite; (ii) Cs will be efficiently retained by cation exchange on illite; (iii) Ra will be retained via co-precipitation with barite; and although (iv) Sr will be retained via co-precipitation with calcite and cation exchange on illite, the retention capacity of the Quaternary till for Sr is limited. 相似文献
585.
Turbiditic levee deposition in response to climate changes: The Var Sedimentary Ridge (Ligurian Sea)
Stéphan J. Jorry Isabelle Jégou Laurent Emmanuel Ricardo Silva Jacinto Bruno Savoye 《Marine Geology》2011,279(1-4):148-161
The Var turbiditic system located in the Ligurian Sea (SE France) is an intermediate mud/sand-rich system. The particularity of the Var deep-sea fan is its single channel with abrupt bends and its asymmetric and hyper-developed levee on the right hand side: the Var Sedimentary Ridge. Long-term sediment accumulation on the Var Sedimentary Ridge makes this an ideal target for studying the link between onshore climate change and deep-sea turbidite stratigraphy. This paper focuses on the establishment of the first detailed stratigraphy of the levee, which is used to analyze the timing of overbank deposition throughout the last deglaciation. Main results indicate that high variability in turbidite frequencies and deposition rates along the Var Sedimentary Ridge are determined by two main parameters: 1) the progressive decrease of the levee height controlling the ability of turbidity currents to spill out from the channel onto the levee, and 2) climatic variations affecting the drainage basin, in particular changes in glacial condition since late Last Glacial Maximum to early Holocene. Compared to other deep-water areas, this study confirms the ability of turbiditic systems to record past climatic events on millennial timescales, and underlines the influence of European deglaciation on the observed decrease in turbidite activity in the Var canyon. The presence of a very narrow continental shelf and a single, large channel-levee system makes the Var Sedimentary Ridge a unique example of climate-controlled turbiditic accumulations. 相似文献
586.
Anne Nédélec Jean-Louis Paquette Jean-Luc Bouchez Philippe Olivier Bruno Ralison 《Geodinamica Acta》2013,26(1):48-56
AbstractStratoid granites constitute a major feature of the Precambrien basement of Madagascar. A detailed structural study was carried out NNW of Antananarivo. New zircon isotopic data on a typical alkaline granite ascertain their Panafrican age (585 Ma). The sheets of granites metric to kilometric of thickness, are interlayered with migmatitic gneisses and amphibolites. Their internal structures, determined by anisotropy of magnetic susceptibility measurements, everywhere yield foliations gently dipping to the west, and lineations striking WSW-ENE. These structures were mostly acquired at the magmatic stage in the granites, in the country-rocks they resulted from high-temperature plastic deformation.The very constant structural pattern, interpreted in terms of shear deformation of a section of the crust, as well as the low P (P = 4 - 5 kb) - high T (T # 750°C) conditions, suggest that the emplacement of the stratoid granites was coeval with a late-orogenic stage in the Panafrican Mozambique belt, and possibly linked to the thinning of the lithosphere. 相似文献
587.
Michel Pichavant Ida Di Carlo Silvio G. Rotolo Bruno Scaillet Alain Burgisser Nolwenn Le Gall Caroline Martel 《Contributions to Mineralogy and Petrology》2013,166(2):545-561
To test mechanisms of basaltic magma degassing, continuous decompressions of volatile-bearing (2.7–3.8 wt% H2O, 600–1,300 ppm CO2) Stromboli melts were performed from 250–200 to 50–25 MPa at 1,180–1,140 °C. Ascent rates were varied from 0.25 to ~1.5 m/s. Glasses after decompression show a wide range of textures, from totally bubble-free to bubble-rich, the latter with bubble number densities from 104 to 106 cm?3, similar to Stromboli pumices. Vesicularities range from 0 to ~20 vol%. Final melt H2O concentrations are homogeneous and always close to solubilities. In contrast, the rate of vesiculation controls the final melt CO2 concentration. High vesicularity charges have glass CO2 concentrations that follow theoretical equilibrium degassing paths, whereas glasses from low vesicularity charges show marked deviations from equilibrium, with CO2 concentrations up to one order of magnitude higher than solubilities. FTIR profiles and maps reveal glass CO2 concentration gradients near the gas–melt interface. Our results stress the importance of bubble nucleation and growth, and of volatile diffusivities, for basaltic melt degassing. Two characteristic distances, the gas interface distance (distance either between bubbles or to gas–melt interfaces) and the volatile diffusion distance, control the degassing process. Melts containing numerous and large bubbles have gas interface distances shorter than volatile diffusion distances, and degassing proceeds by equilibrium partitioning of CO2 and H2O between melt and gas bubbles. For melts where either bubble nucleation is inhibited or bubble growth is limited, gas interface distances are longer than volatile diffusion distances. Degassing proceeds by diffusive volatile transfer at the gas–melt interface and is kinetically limited by the diffusivities of volatiles in the melt. Our experiments show that CO2-oversaturated melts can be generated as a result of magma decompression. They provide a new explanation for the occurrence of CO2-rich natural basaltic glasses and open new perspectives for understanding explosive basaltic volcanism. 相似文献
588.
Thierry Desjardins Bruno Turcq Jean-Pierre Nguetnkam Gaston Achoundong Magloire Mandeng-Yogo Fethyé Cetin Anne-Marie Lézine 《Comptes Rendus Geoscience》2013,345(7-8):266-271
In order to better understand the dynamics of the forest–savanna mosaic from central Cameroon, we analyzed 13C and 14C profiles of six oxisols: two under forests and four under savannas. The δ13C soil profiles collected in the forests indicate that these environments are stable at least since the mid-Holocene, whereas the areas currently covered by savannas were formerly occupied by more forested vegetations. The 14C dating of organic matter indicate that the late extension of the savannas in central Cameroon date from the Late Holocene, starting from 4000–3500 14C yr BP. 相似文献
589.
590.
Satellite clock bias estimation for iGPS 总被引:4,自引:0,他引:4
John Pratt Penina Axelrad Kristine M. Larson Bruno Lesage Richard Gerren Nicholas DiOrio 《GPS Solutions》2013,17(3):381-389
The High Integrity GPS program seeks to provide enhanced navigation performance by combining conventional GPS with a communications and ranging broadcast from the Iridium® Communications System. Through clock and message aiding, it would enable existing GPS receivers to acquire and track in more challenging environments. As is the case for standard GPS, accurate and precise timing is key to performance. An approach is presented for estimating the bias of each Iridium satellite clock using satellite-to-ground and satellite-to-satellite measurements. The satellite clock bias estimates are based on a Kalman filter that incorporates code-type observations from the measurements at 10 s intervals. Filter parameters are set based on the expected behavior of the clocks, allowing for discontinuous bias and frequency adjustments due to ground commands. Typical results show the current filter to be accurate to within 200 ns while always meeting the initial system specification of half a microsecond. 相似文献