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Non-linear MHD simulations of QH-mode and Type I ELMy H-mode DIIID plasmas and implications for ITER high Q scenarios
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Immiscible two-phase Darcy flow model accounting for vanishing and discontinuous capillary pressures: application to the flow in fractured porous media
No full textInternational audienceFully implicit time-space discretizations applied to the two-phase Darcy flow problem lead to the systems of nonlinear equations, which are traditionally solved by some variant of Newton's method. The efficiency of the resulting algorithms heavily depends on the choice of the primary unknowns since Newton's method is not invariant with respect to a nonlinear change of variable. In this regard the role of capillary pressure/saturation relation is paramount because the choice of primary unknowns is restricted by its shape. We propose an elegant mathematical framework for two-phase flow in heterogeneous porous media resulting in a family of formulations, which apply to general monotone capillary pressure/saturation relations and handle the saturation jumps at rocktype interfaces. The presented approach is applied to the hybrid dimensional model of two phase water-gas Darcy flow in fractured porous media for which the fractures are modeled as interfaces of co-dimension one. The problem is discretized using an extension of Vertex Approximate Gradient scheme. As for the phase pressure formulation, the discrete model requires only two unknowns by degree of freedom
A domain decomposition method to couple nonisothermal compositional gas liquid Darcy and free gas flows
No full textA domain decomposition algorithm is introduced to couple nonisothermal compositional gas liquid Darcy and free gas flow and transport. At each time step, our algorithm solves iteratively the nonlinear system coupling the nonisothermal compositional Darcy flow in the porous medium, the RANS gas flow in the free-flow domain, and the transport of the species and of energy in the free-flow domain. In order to speed up the convergence of the algorithm, the transmission conditions at the interface are replaced by Robin type boundary conditions. The Robin coefficients are obtained from a diagonal approximation of the Dirichlet to Neumann operator related to a simplified model in the neighbouring subdomain. The efficiency of our domain decomposition algorithm is assessed on several test cases focusing on the modeling of the mass and energy exchanges at the interface between the geological formation and the ventilation galleries of geological radioactive waste disposal
Sardinia Radio Telescope observations of Abell 194 - the intra-cluster magnetic field power spectrum
No full textInternational audienceAims. We study the intra-cluster magnetic field in the poor galaxy cluster Abell 194 by complementing radio data, at different frequencies, with data in the optical and X-ray bands.Methods. We analyzed new total intensity and polarization observations of Abell 194 obtained with the Sardinia Radio Telescope (SRT). We used the SRT data in combination with archival Very Large Array observations to derive both the spectral aging and rotation measure (RM) images of the radio galaxies 3C 40A and 3C 40B embedded in Abell 194. To obtain new additional insights into the cluster structure, we investigated the redshifts of 1893 galaxies, resulting in a sample of 143 fiducial cluster members. We analyzed the available ROSAT and Chandra observations to measure the electron density profile of the galaxy cluster.Results. The optical analysis indicates that Abell 194 does not show a major and recent cluster merger, but rather agrees with a scenario of accretion of small groups, mainly along the NE−SW direction. Under the minimum energy assumption, the lifetimes of synchrotron electrons in 3C 40 B measured from the spectral break are found to be 157 ± 11 Myr. The break frequency image and the electron density profile inferred from the X-ray emission are used in combination with the RM data to constrain the intra-cluster magnetic field power spectrum. By assuming a Kolmogorov power-law power spectrum with a minimum scale of fluctuations of Λmin = 1 kpc, we find that the RM data in Abell 194 are well described by a magnetic field with a maximum scale of fluctuations of Λmax = (64 ± 24) kpc. We find a central magnetic field strength of ⟨ B0 ⟩ = (1.5 ± 0.2) μG, which is the lowest ever measured so far in galaxy clusters based on Faraday rotation analysis. Further out, the field decreases with the radius following the gas density to the power of η = 1.1 ± 0.2. Comparing Abell 194 with a small sample of galaxy clusters, there is a hint of a trend between central electron densities and magnetic field strengths.Key words: galaxies: clusters: general / galaxies: clusters: individual: Abell 194 / magnetic fields / large-scale structure of Univers
Probabilistic Schedulability Analysis for Fixed Priority Mixed Criticality Real-Time Systems
No full textInternational audienceIn this paper we present a probabilistic response time analysis for mixed criticality real-time systems running on a single processor according to a fixed priority pre-emptive scheduling policy. The analysis extends the existing state of the art probabilistic analysis to the case of mixed criticalities, taking into account both the level of assurance at which each task needs to be certified, as well as the possible criticalities at which the system may execute. The proposed analysis is formally presented as well as explained with the aid of an illustrative example
Revue des méthodes multiparamétriques pour l’estimation de la qualité des sols dans le cadre de l’aménagement du territoire
No full textInternational audienceL’étalement urbain affecte principalement les territoires agricoles, dont la plupart ont un fort potentiel agronomique. Afin de contribuer à une gestion durable des sols, les indices de qualité des sols pourraient permettre de caractériser l’adéquation des sols à leurs potentiels usages agricoles, forestiers ou urbains dans le cadre de l’aménagement du territoire. Les indices de qualité des sols ont pour principal objectif de fournir une information synthétique de l’état des sols. Cependant, leur mise en oeuvre est confrontée à la difficulté de rendre compte de la complexité du sol à travers un seul indice. Il existe ainsi une multitude d’indices de qualité des sols. Le choix des propriétés du sol à intégrer est primordial et dépend souvent de l’utilisation finale de l’indice, mais la manière de combiner les propriétés du sol et le poids qui leur est donné est tout aussi important. L’objectif de cette synthèse est ainsi de présenter les méthodes d’évaluation de la qualité des sols, dans leur aspect technique, et d’engager une réflexion sur les avantages et les inconvénients de chacune de ces approches. La définition de la qualité des sols impliquant l’utilisation de propriétés physiques, chimiques et biologiques, nous traitons essentiellement des méthodes multiparamétriques. Cette synthèse bibliographique montre qu’il est possible de passer outre certaines difficultés reconnues dans la conception de tels indices, en stratifiant judicieusement les usages et les fonctions du sol à prendre en compte selon l’échelle d’évaluation et en évitant l’agrégation des indicateurs en une note unique
The Future of Performativity.
No full textInternational audienceTwo recent publications have deepened the ongoing debate on the uses and abuses of performativity in the social sciences and specifically the way it has been erected as a comprehensive epistemic scheme for economics. The Provoked Economy (2014), by Fabian Muniesa triggered lots of criticisms and debates that are well echoed in the collective work edited by Ivan Boldyrev and Ekaterina Svetlova, Enacting Dismal Science (2016a).1 The goal of this review is to present and discuss both and, as a by-product, to advocate for a pragmatic and institutionally grounded use of the concept of performativity in economics
Post-transcriptional gene silencing mediated by microRNAs is controlled by nucleoplasmic Sfpq
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The VIMOS Public Extragalactic Redshift Survey (VIPERS): The growth of structure at 0.5 < z < 1.2 from redshift-space distortions in the clustering of the PDR-2 final sample
No full textInternational audienceWe present measurements of the growth rate of cosmological structure from the modelling of the anisotropic galaxy clustering measured in the final data release of the VIPERS survey. The analysis is carried out in configuration space and based on measurements of the first two even multipole moments of the anisotropic galaxy auto-correlation function, in two redshift bins spanning the range 0.5 <z< 1.2. We provide robust and cosmology-independent corrections for the VIPERS angular selection function, allowing recovery of the underlying clustering amplitude at the percent level down to the Mpc scale. We discuss several improvements on the non-linear modelling of redshift-space distortions (RSD) and perform detailed tests of a variety of approaches against a set of realistic VIPERS-like mock realisations. This includes using novel fitting functions to describe the velocity divergence and density power spectra Pθθ and Pδθ that appear in RSD models. These tests show that we are able to measure the growth rate with negligible bias down to separations of 5 h-1 Mpc. Interestingly, the application to real data shows a weaker sensitivity to the details of non-linear RSD corrections compared to mock results. We obtain consistent values for the growth rate times the matter power spectrum normalisation parameter of fσ8 = 0.55 ± 0.12 and 0.40 ± 0.11 at effective redshifts of z = 0.6 and z = 0.86 respectively. These results are in agreement with standard cosmology predictions assuming Einstein gravity in a ΛCDM background.Key words: cosmology: observations / large-scale structure of Universe / galaxies: high-redshift / galaxies: statistics⋆ Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programs 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. The VIPERS web site is http://www.vipers.inaf.it
Multi-harvesting solution for autonomous sensing node based on LoRa Technology
No full textInternational audienceIn this paper, different energy harvesting solutions for an autonomous miniature wireless sensing node are invistagated.The communication part is realized with Low Power Wide Area Network (LP-WAN) LoRa technology that combine lowpowerand long range capabilities. Solar, Thermal and Piezo harvesting techniques are compared for autonomous sensing application