Repetitive Model Refactoring for Design Space Exploration of Intensive Signal Processing Applications

The efficient design of computation intensive multidimensional signal processing application requires to deal with three kinds of constraints: those implied by the data dependencies, the non functional requirements (real-time, power consumption) and the availability of resources of the execution platform. We propose here a strategy to use a refactoring tool dedicated to this kind of applications to help explore the design space. This strategy is illustrated on an industrial radar application modeled using the Modeling and Analysis of Real-time and Embedded systems (MARTE) UML profile. It allows to find good trade-offs in the usage of storage and computation resources and in the parallelism (both task and data parallelism) exploitation

Elaboration of metallic compacts with high porosity for mechanical supports of SOFC

The development of third generation Solid Oxide Fuel Cells (SOFC) with metallic mechanical supports presents several advantages over that of ceramic stacks by offering a lower cost and longer lifetime of the stacks. As a consequence, it is necessary to prepare metallic porous compacts that remain stable at the operating temperature of the SOFC (700–800 C) under reductive atmosphere. This paper presents an innovative process to elaborate iron, nickel and cobalt porous compacts. The process is based on the thermal decomposition of metal oxalate precursors with controlled morphology into metallic powders with coralline shape. Uniaxial compaction of such powders (without binder addition to the powders) under low uniaxial pressures (rising from 20 to 100 MPa) gave rise to green compacts with high porosity and good mechanical properties. After annealing at 800 C under H2 atmosphere, the compacts still present interconnected porosity high enough to allow sufficient gas flow to feed a SOFC single cell in hydrogen: the porosity rises from 25 to 50% for iron compacts, from 20 to 50% for cobalt compacts, and is higher than 40% for nickel compacts. Results from physicochemical characterization (XRD, SEM, gas permeation, Hg porosimetry) corroborated the process for SOFC application

A new route to prepare anodic coatings on dense and porous metallic supports for SOFC application

Metallic cell supports have been developed for the new generation of fuel cells. Sol–gel process has been used to prepare anodic coatings on these supports at moderate thermal treatment temperature, in order to keep a good support mechanical behavior and limit metallic corrosion. Indeed, we take advantage of the numerous reaction routes that sol–gel method can offer to first synthesize NiO–YSZ (yttria-stabilized zirconia) homogeneous composites, and then to process films of different thicknesses on metallic supports by dipcoating. In this work, the metallic supports could be either dense or porous. To begin with, duplex microstructured anodes were prepared from both thin and thick layers, directly deposited on dense metallic supports. The interfacial anodic layer, around 100 nm thick, improves adhesion and accommodates stresses between metallic interconnect and active thick anode. Moreover, by dipping the substrate into an optimized slurry containing sol–gel composite powders, films of a few microns thick have been obtained and constituted the active anodic part. A heat treatment at only 800 °C leads to a coherent anodic duplex stacking which is continuous, homogeneous and adherent. Subsequently, thick anodic films have also been deposited on two different porous supports, with both dip-coating process and slurries routes. These thick anodic coatings were characterized after thermal treatment at 800 °C

Lithium conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 obtained via solution chemistry

NaSICON-type lithium conductor Li1.3Al0.3Ti1.7(PO4)3 (LATP) is synthesized with controlled grain size and composition using solution chemistry. After thermal treatment at 850 C, sub-micronic crystallized powders with high purity are obtained. They are converted into ceramic through Spark Plasma Sintering at 850–1000 C. By varying the processing parameters, pellet with conductivities up to 1.6 * 10−4 S/cm with density of 97% of the theoretical density have been obtained. XRD, FEG-SEM, ac-impedance and Vickers indentation were used to characterize the products. The influence of sintering parameters on pellet composition, microstructure and conductivity is discussed in addition to the analysis of the mechanical behavior of the grains interfaces

Dense on Porous Solid LATP Electrolyte System: Preparation and Conductivity Measurement

A dense membrane of lithium aluminum titanium phosphate Li1+xAlxTi2-x(PO4)3, x=0.3 (LATP) is deposited on a porous LATP substrate via wet chemistry. In the polymerized complex process, phosphate precursors with different active groups and steric hindrance are selected to tune precursor’s reactivity. Rheological studies and microstructural observations lead to the selection of an LATP powder slurry charged with lithium, aluminum, titanium, and phosphate ion precursors. The optimized formulation is impregnated into a porous LATP substrate. After thermal treatment, dense LATP membranes on top of a porous LATP substrate are obtained with conductivities as high as 3 x 10-4 S/cm for the dense part, the porous part acting as a mechanical support. An original Van der Pauw impedance setup is validated for the measurement of the ionic conductivity of such dense/ porous systems

Assessing the effect of sample bias correction in species distribution models

1. Open-source biodiversity databases contain a large number of species occurrence records but are often spatially biased; which affects the reliability of species distribution models based on these records. Sample bias correction techniques require data filtering which comes at the cost of record numbers, or require considerable additional sampling effort. Since independent data is rarely available, assessment of the correction technique often relies solely on performance metrics computed using subsets of the available – biased – data, which may prove misleading. 2. Here, we assess the extent to which an acknowledged sample bias correction technique is likely to improve models’ ability to predict species distributions in the absence of independent data. We assessed variation in model predictions induced by the aforementioned correction and model stochasticity; the variability between model replicates related to a random component (pseudo-absences sets and cross-validation subsets). We present, then, an index of the effect of correction relative to model stochasticity; the Relative Overlap Index (ROI). We investigated whether the ROI better represented the effect of correction than classic performance metrics (Boyce index, cAUC, AUC and TSS) and absolute overlap metrics (Schoener’s D, Pearson’s and Spearman’s correlation coefficients) when considering data related to 64 vertebrate species and 21 virtual species with a generated sample bias. 3. When based on absolute overlaps and cross-validation performance metrics, we found that correction produced no significant effects. When considering its effect relative to model stochasticity, the effect of correction was strong for most species at one of the three sites. The use of virtual species enabled us to verify that the correction technique improved both distribution predictions and the biological relevance of the selected variables at the specific site, when these were not correlated with sample bias patterns. 4. In the absence of additional independent data, the assessment of sample bias correction based on subsample data may be misleading. We propose to investigate both the biological relevance of environmental variables selected, and, the effect of sample bias correction based on its effect relative to model stochasticity. Accessibility maps Cross-validation Performance metrics Overlap Pseudo-absence selection Terrestrial vertebrates Variable selection Virtual speciespublishedVersio

Quelles dynamiques de l'emploi en milieu rural : peut-on oser l'expression de « vitalité cachée » ?

La controverse joue un rôle essentiel dans les résultats et le progrès des sciences sociales. L'Emploi rural, une vitalité cachée, cette recherche collective et pluraliste sur l'avenir des emplois dans l'espace rural français publiée fin 1995, n'a pas épuisé les divergences d'interprétation sur le sujet et continue, une fois achevée, à opposer même les auteurs entre eux. L'objectif de cette table ronde, qui s'est tenue en décembre 1996, fut d'approfondir ces désaccords par leur discussion. Dans ce débat, chacun cherche, dans une langue vive et polémique, à préciser sa pensée en même temps que ce qui fait contradiction. On aboutit pourtant à un consensus : pour avancer plus loin dans l'analyse de phénomènes sociaux encore incertains, il faut théoriser les désaccords et prolonger la recherche à plusieurs voies.Dynamics of the employment in rural areas : may we speak of a vitality ? This paper relates the debate organized after the publication of L’Emploi rural, une vitalité cachée ?, in order to cross the contradictory points of view of the authors in the face of an outward sociologist reader. Though it was quite hot, the discussion has deepened the analysis and opened up to new approaches and questions

DÉBAT

 Nicole Mathieu : Il est important que Bohdan ait inauguré ce séminaire, parce que je crois qu’il faudrait réintroduire dans cette maison une certaine tonalité de travail, une façon de faire de la géographie, qui repose, comme cet exposé, sur une grande sincérité dans l’affirmation de la position exprimée, sur une vision prospective, tournée vers ce qui risque de se passer en Europe, ou dans les Europes, et sur une vision qui ne soit pas trop étroite, trop disciplinaire, qui permette de réflé..

DÉBAT

 Nicole Mathieu : Il est important que Bohdan ait inauguré ce séminaire, parce que je crois qu’il faudrait réintroduire dans cette maison une certaine tonalité de travail, une façon de faire de la géographie, qui repose, comme cet exposé, sur une grande sincérité dans l’affirmation de la position exprimée, sur une vision prospective, tournée vers ce qui risque de se passer en Europe, ou dans les Europes, et sur une vision qui ne soit pas trop étroite, trop disciplinaire, qui permette de réflé..