Two examples of expert knowledge based system for avalanche forecasting and protection     

Laurent Buisson  Gérald Giraud 《Surveys in Geophysics》1995,16(5-6):603-619

  相似文献   

Evolution qualitative à long terme des rotifères du Lac Léman     

Gérard Balvay  Monique Laurent 《Aquatic Sciences - Research Across Boundaries》1990,52(2):156-161

Seventy-five species and lower taxonomic units of rotifers have been identified in Lake Geneva (= lac Léman); seven species and one form are new for the lake. When using indicators of trophic conditions, the qualitative composition of the biocenosis is still dominated by oligo-mesotrophic lake indicators, mixed with eutrophic and oligotrophic ones. However the rotifer biocenosis has not yet reached a steady state.

  相似文献   

Optimization framework for calibration of constitutive models enhanced by neural networks   总被引：1，自引：0，他引：1  

Rafał F. Obrzud  Laurent Vulliet  Andrzej Truty 《国际地质力学数值与分析法杂志》2009,33(1):71-94

A two‐level procedure designed for the estimation of constitutive model parameters is presented in this paper. The neural network (NN) approach at the first level is applied to achieve the first approximation of parameters. This technique is used to avoid potential pitfalls related to the conventional gradient‐based optimization techniques, considered here as a corrector that improves predicted parameters. The feed‐forward NN (FFNN) and the modified Gauss–Newton algorithms are briefly presented. The proposed framework is verified for the elasto‐plastic modified Cam Clay model that can be calibrated based on standard triaxial laboratory tests, i.e. the isotropic consolidation test and the drained compression test. Two different formulations of the input data to the NN, enhanced by a dimensional reduction of experimental data using principal component analysis, are presented. The determination of model characteristics is demonstrated, first on numerical pseudo‐experiments and then on the experimental data. The efficiency of the proposed approach by means of accuracy and computational effort is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Fluid flow behaviour in reactivated hydrocarbon traps: Assessing fluid circulation along natural complex fault systems using numerical fluid flow simulation     

Laurent Langhi  Y. Zhang  A. Gartrell  J.R. Underschultz  D.N. Dewhurst 《Journal of Geochemical Exploration》2009

  相似文献   

Seismically induced shale diapirism: the Mine d’Or section,Vilaine estuary,Southern Brittany     

B. Van Vliet-Lanoe  C. Hibsch  L. Csontos  S. Jegouzo  B. Hallégouët  M. Laurent  A. Maygari  D. Mercier  P. Voinchet 《International Journal of Earth Sciences》2009,98(5):969-984

The Pénestin section (southern Brittany) presents large regular undulations, commonly interpreted as evidence of periglacial pingos. It is an upper Neogene palaeoestuary of the Vilaine River reactivated during the middle Quaternary (middle terrace). It is incised into a thick kaolinitic saprolite and deformed by saprolite diapirs. This paper presents the arguments leading to a mechanistic interpretation of the deformations at Pénestin. Neither recent transpressive tectonics nor diagnostic evidence of periglacial pingo have been found despite evidence for a late paleo-permafrost. The major deformational process is shale diapirism, initially triggered by co-seismic water supply, with further loading and lateral spreading on an already deformed and deeply weathered basement, which allowed the shale diapirism to develop. Deformations are favoured by the liquefaction of the saprolite and a seaward mass movement and recorded, rather distant, effects of an earthquake (c. 280 ka B.P.) resulting from the progressive subsidence of the southern Armorican margin. These deformations triggered by an earthquake are similar to those induced by classical shale diapirism. They are probably common in tectonically active continental environments with shallow water table.  相似文献   

New aspects of magma storage and transfer     

Bruno Scaillet  Laurent Arbaret  Fabrice Gaillard 《Comptes Rendus Geoscience》2019,351(8):523-524

  相似文献   

Structural Interpretation of Sparse Fault Data Using Graph Theory and Geological Rules     

Godefroy  G.  Caumon  G.  Laurent  G.  Bonneau  F. 《Mathematical Geosciences》2019,51(8):1091-1107

Structural uncertainty exists when associating sparse fault interpretations made from two-dimensional seismic lines or limited outcrop observations. Here, a graph formalism is proposed that describes the problem of associating spatial fault evidence. A combinatorial analysis, relying on this formalism, shows that the number of association scenarios is given by the Bell number, and increases exponentially with the number of pieces of evidence. As a result, the complete exploration of uncertainties is computationally highly challenging. The available prior geological knowledge is expressed by numerical rules to reduce the number of scenarios, and the graph formalism makes structural interpretation easier to reproduce than manual interpretation. The Bron–Kerbosch algorithm, which finds maximal cliques in undirected graphs, is used to detect major possible structures. This framework opens the way to a numerically assisted exploration of uncertainties during structural interpretation.

  相似文献   

Phytoplankton geographic spatialization in two ponds in Limousin (France)     

Laurent Touchart  Jrme Bouny 《Applied geography (Sevenoaks, England)》2008,28(4):295-310

Phytoplankton distribution was not homogeneous among Limousin ponds and within each pond, as shown by chlorophyll a and diatoms in two representative eutrophic ponds. On a small cartographic scale, differences depended on geographic location and water temperature. Spring bloom occurred with a time-lag of several weeks in the highland pond. On a large-scale geographic distribution depended on hydroclimatic factors, especially wind direction and inflow of the rivers. The high concentrations of chlorophyll a near the dam of the water bodies roughly coincided with the maximum fetch and the direction of the dominant winds during the investigations. In both ponds the heaviest algae seemed not to be influenced by wind currents and the greater number of diatoms upstream in the highland pond was probably due to inflow of silica from the river. Phytoplankton mapping is more explanatory and rigorous than Secchi disk transparency mapping, it is useful to the regional authorities for zoning activities: bathing should be avoided in bays and along longitudinal shores, fishing location may be less restrictive. In plateau regions in general phytoplankton is not randomly distributed and spatial heterogeneity of ponds is not only vertical but also horizontal. Deep and embanked ponds are complex organisms analogous to great lakes for some features and to shallow water bodies for other ones.  相似文献   

Comparison of Earth’s magnetospheric magnetic field models in the context of cosmic ray physics   总被引：1，自引：0，他引：1  

Laurent Desorgher  Karel Kudela  Erwin O. Flückiger  Rolf Bütikofer  Marisa Storini  Vladimir Kalegaev 《Acta Geophysica》2009,57(1):75-87

Over the last two decades, models of the Earth’s magnetospheric magnetic field have been continuously improved to describe more precisely the different magnetospheric current systems (magnetopause current, symmetric and partial ring currents, tail currents and field aligned currents). In this paper we compare the different Tsyganenko models and the Alexeev and Feldstein model in the context of cosmic ray physics. We compare the vertical cutoff rigidity and asymptotic direction of vertical incidence obtained with these models for the January 20, 2005, ground level enhancement and for the big magnetic storm of April 6, 2000. For the event of January 20, 2005, we study the impact of the differences in asymptotic direction obtained with the models on the radiation dose computation at aircraft altitude. For the magnetic storm of April 6, 2000, we discuss the importance of the different magnetospheric current systems in causing cutoff rigidity variations. Finally we summarise the advantages and drawbacks of the different models in the context of space weather.  相似文献   

Distributed hydrologic and hydraulic modelling with radar rainfall input: Reconstruction of the 8–9 September 2002 catastrophic flood event in the Gard region,France     

Laurent Bonnifait  Guy Delrieu  Matthieu Le Lay  Brice Boudevillain  Arielle Masson  Philippe Belleudy  Eric Gaume  Georges-Marie Saulnier 《Advances in water resources》2009

On 8–9 September 2002, an extreme rainfall event caused by a stationary mesoscale convective system (MCS) occurred in the Gard region, France. Distributed hydrologic and hydraulic modelling has been carried out to assess and compare the various sources of data collected operationally and during the post-event field surveys. Distributed hydrological modelling was performed with n-TOPMODELs and assessed for ungauged basins with the discharge estimates of the post-event surveys. A careful examination of the occurrence in time and space of the flash floods over the head watersheds indicates that flooding was controlled by the trajectory of the convective part of the MCS. Stationarity of the MCS over the Gardon watershed (1858 km² at Remoulins) for 28 h was responsible for the exceptional magnitude of the flood at this scale. The flood dynamics were characterized by an extensive inundation of the Gardonnenque plain upstream of the Gardon Gorges resulting in a significant peak flow reduction downstream. One-dimensional unsteady-flow hydraulic modelling was found to be required to reproduce these dynamics. Hydraulic modelling also proved to be potentially useful for the critical analysis and extrapolation of operational discharge rating curves.  相似文献