The double ITCZ bias in CMIP5 models: interaction between SST,large-scale circulation and precipitation     

Boutheina Oueslati  Gilles Bellon 《Climate Dynamics》2015,44(3-4):585-607

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Simulation of damage–permeability coupling for mortar under dynamic loads     

Wen Chen  Christian La Borderie  Olivier Maurel  Gilles Pijaudier‐Cabot  Franck Rey‐Bethbeder 《国际地质力学数值与分析法杂志》2014,38(5):457-474

The results reported in this paper deal with the simulation of damage in cohesive geomaterials such as rocks or concrete subjected to dynamic loads. The practical objective is to stimulate the production of tight gas reservoirs with a technique that is an alternative to hydraulic fracturing. The principle is that when subjected to dynamic loads, cohesive materials such as concrete, rocks or ceramics exhibit distributed micro‐cracking as opposed to localised cracking observed under static loads. Hence, a low permeability rock containing gas trapped into occluded pores can be fragmented with the help of dynamic loads, and gas can be extracted in a much more efficient way compared with hydraulic fracturing, where only large macro cracks are formed with very few connections between occluded pores. At the stage of laboratory development of this technique, compressive underwater shock waves have been used to increase the intrinsic permeability of concrete specimens. In a previous study, pressure waves generated by pulsed arc electrohydraulic discharges in water were used in order to induce micro‐cracking and an increase of average permeability of concrete hollow cylinders subjected to confinement stresses (equivalent to geostatic stresses). We discuss here a 3‐D anisotropic constitutive model aimed at describing the dynamic response of these specimens. It is based on rate‐dependent continuum damage constitutive relations. Crack closure effects and damage‐induced anisotropy are included in the model. The directional growth of damage is related to the directional growth of material intrinsic permeability. Numerical simulations of damage induced by shock waves show good agreement with the experiments for various confinement levels of the specimens. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Erratum to: An event-by-event assessment of tropical intraseasonal perturbations for general circulation models     

Jean Philippe Duvel  Hugo Bellenger  Gilles Bellon  Marine Remaud 《Climate Dynamics》2013,40(9-10):2575-2575

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The COVID-19 pandemic and global environmental change: Emerging research needs     

Robert Barouki  Manolis Kogevinas  Karine Audouze  Kristine Belesova  Ake Bergman  Linda Birnbaum  Sandra Boekhold  Sebastien Denys  Celine Desseille  Elina Drakvik  Howard Frumkin  Jeanne Garric  Delphine Destoumieux-Garzon  Andrew Haines  Anke Huss  Genon Jensen  Spyros Karakitsios  Jana Klanova  Paolo Vineis 《Chemie der Erde / Geochemistry》2012

The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

New models for heater wells in subsurface simulations, with application to the in situ upgrading of oil shale     

Gilles Aouizerate  Louis J. Durlofsky  Pierre Samier 《Computational Geosciences》2012,16(2):519-533

Downhole electrical heating can be used to achieve the high temperatures required for in situ upgrading of oil shale or oil sands. Heater-well models are needed if this process is to be simulated accurately. The traditional Peaceman approach used for fluid injection and production wells may not be applicable because it does not capture transient effects, which can be important in downhole heater models. Standard models also neglect the effects of heterogeneity and temperature dependence in the rock properties. Here, we develop two new models for representing heater wells in reservoir simulators. The first model is applicable for homogeneous systems with properties that are not temperature dependent. For such cases, we develop a semi-analytical procedure based on Green’s functions to construct time-dependent heater-well indexes and heater-block thermal transmissibilities. For the general case, which can include both fine-scale heterogeneity and nonlinearity due to the temperature dependence of rock properties, we present a numerical procedure for constructing the heater-well model. This technique is essentially a near-well upscaling method and requires a local fine-scale solution in the near-well region. The boundary conditions are determined using a local-global treatment. The accuracy of the new heater-well models is demonstrated through comparison to reference solutions for example problems. The approach is then applied for the coarse-scale modeling of the in situ upgrading of oil shale, which entails a thermal-compositional simulation with chemical reactions. The model is shown to provide an accurate and efficient solution for this challenging problem.  相似文献   

Radiative properties of stellar plasmas and open challenges     

S. Turck-Chi??ze  G. Loisel  D. Gilles  L. Piau  C. Blancard  T. Blenski  M. Busquet  T. Caillaud  P. Coss??  F. Delahaye  G. Faussurier  J. Fariaut  F. Gilleron  J. A. Guzik  J. Harris  D. P. Kilcrease  N. H. Magee  J. C. Pain  Q. Porcherot  M. Poirier  G. Soullier  C. J. Zeippen  S. Bastiani-Ceccotti  C. Reverdin  V. Silvert  F. Thais  B. Villette 《Astrophysics and Space Science》2011,336(1):103-109

The lifetime of solar-like stars, the envelope structure of more massive stars, and stellar acoustic frequencies largely depend on the radiative properties of the stellar plasma. Up to now, these complex quantities have been estimated only theoretically. The development of the powerful tools of helio- and astero- seismology has made it possible to gain insights on the interiors of stars. Consequently, increased emphasis is now placed on knowledge of the monochromatic opacity coefficients. Here we review how these radiative properties play a role, and where they are most important. We then concentrate specifically on the envelopes of ?? Cephei variable stars. We discuss the dispersion of eight different theoretical estimates of the monochromatic opacity spectrum and the challenges we need to face to check these calculations experimentally.  相似文献   

The Key Tuffite,Matagami Camp,Abitibi Greenstone Belt,Canada: petrogenesis and implications for VMS formation and exploration     

Dominique Genna  Damien Gaboury  Gilles Roy 《Mineralium Deposita》2014,49(4):489-512

The Key Tuffite is a stratigraphic marker unit for most of the zinc-rich volcanogenic massive sulfide deposits of the Matagami Camp in the Abitibi Greenstone Belt. This 2- to 6-m-thick unit was previously interpreted as a mixture of ash fall (andesitic to rhyolitic tuffaceous components) and volcanogenic massive sulfide (VMS)-related chemical seafloor precipitate (exhalative component). Previous attempts to develop geochemical exploration vectoring tools using metal content within the Key Tuffite were mostly inconclusive due to the complex nature of the Key Tuffite unit and a poor understanding of its composition, origin and relationship with the VMS-forming hydrothermal systems. Detailed mapping and thorough lithogeochemistry of the Key Tuffite in the vicinity of the Perseverance and Bracemac-McLeod deposits indicate that the Key Tuffite is a homogeneous calc-alkaline, andesitic tuff that was deposited before the VMS deposits were formed. The unit is mostly devoid of exhalative component, but it is strongly hydrothermally altered close to orebodies. This is characterized by a strong proximal chloritization and a distal sericitization, which grades laterally into the unaltered Key Tuffite. Neither the Key Tuffite nor the ore was formed by seafloor exhalative processes for the two studied deposits. This probably explains why previously proposed exploration models based on metal scavenging proved unsuccessful and suggests that a re-evaluation of the exhalative model should be done at the scale of the mining camp. However, as shown in this study, hydrothermal alteration can be used to vector towards ore along the Key Tuffite.  相似文献   

Revisiting Multi-Gaussian Kriging with the Nataf Transformation or the Bayes’ Rule for the Estimation of Spatial Distributions     

Gilles Bourgault 《Mathematical Geosciences》2014,46(7):841-868

A multivariate probability transformation between random variables, known as the Nataf transformation, is shown to be the appropriate transformation for multi-Gaussian kriging. It assumes a diagonal Jacobian matrix for the transformation of the random variables between the original space and the Gaussian space. This allows writing the probability transformation between the local conditional probability density function in the original space and the local conditional Gaussian probability density function in the Gaussian space as a ratio equal to the ratio of their respective marginal distributions. Under stationarity, the marginal distribution in the original space is modeled from the data histogram. The stationary marginal standard Gaussian distribution is obtained from the normal scores of the data and the local conditional Gaussian distribution is modeled from the kriging mean and kriging variance of the normal scores of the data. The equality of ratios of distributions has the same form as the Bayes’ rule and the assumption of stationarity of the data histogram can be re-interpreted as the gathering of the prior distribution. Multi-Gaussian kriging can be re-interpreted as an updating of the data histogram by a Gaussian likelihood. The Bayes’ rule allows for an even more general interpretation of spatial estimation in terms of equality for the ratio of the conditional distribution over the marginal distribution in the original data uncertainty space with the same ratio for a model of uncertainty with a distribution that can be modeled using the mean and variance from direct kriging of the original data values. It is based on the principle of conservation of probability ratio and no transformation is required. The local conditional distribution has a variance that is data dependent. When used in sequential simulation mode, it reproduces histogram and variogram of the data, thus providing a new approach for direct simulation in the original value space.  相似文献   

General database for ground water site information   总被引：3，自引：0，他引：3  

de Dreuzy JR  Bodin J  Le Grand H  Davy P  Boulanger D  Battais A  Bour O  Gouze P  Porel G 《Ground water》2006,44(5):743-748

In most cases, analysis and modeling of flow and transport dynamics in ground water systems require long-term, high-quality, and multisource data sets. This paper discusses the structure of a multisite database (the H+ database) developed within the scope of the ERO program (French Environmental Research Observatory, http://www.ore.fr). The database provides an interface between field experimentalists and modelers, which can be used on a daily basis. The database structure enables the storage of a large number of data and data types collected from a given site or multiple-site network. The database is well suited to the integration, backup, and retrieval of data for flow and transport modeling in heterogeneous aquifers. It relies on the definition of standards and uses a templated structure, such that any type of geolocalized data obtained from wells, hydrological stations, and meteorological stations can be handled. New types of platforms other than wells, hydrological stations, and meteorological stations, and new types of experiments and/or parameters could easily be added without modifying the database structure. Thus, we propose that the database structure could be used as a template for designing databases for complex sites. An example application is the H+ database, which gathers data collected from a network of hydrogeological sites associated with the French Environmental Research Observatory.  相似文献   

Assessment of faecal contamination and the relationship between pathogens and faecal bacterial indicators in an estuarine environment (Seine, France)   总被引：2，自引：0，他引：2  

Touron A  Berthe T  Gargala G  Fournier M  Ratajczak M  Servais P  Petit F 《Marine pollution bulletin》2007,54(9):1441-1450

The Seine estuary, one of the largest estuaries of the European northwest continental shelf, is subjected to numerous anthropogenic influences. Here we present an assessment of the microbial faecal contamination of the estuary water. The most vulnerable areas were defined on the basis of the fluxes of indicator organisms and the occurrence of Salmonella and Cryptosporidium sp. and Giardia sp. (oo)cysts. The microbial quality of the water changes from upstream to downstream: in the upstream area, contamination by faecal-indicator bacteria and Salmonella occurs during periods of high flow; in the urbanized area, mid-way between the uppermost areas of the estuary and its mouth, discharge from a wastewater treatment plant and a tributary degrade water quality; at the estuary mouth, the accumulation of microorganisms attached to particles in the maximum turbidity zone, particularly Clostridium perfringens spores and oocysts of Cryptosporidium, is accompanied by inputs of ThC and Escherichia coli from tributaries. In some areas, significant strong relations are observed between Salmonella, (oo)cysts of protozoan, and levels of faecal indicators.  相似文献