MANAGEMENT DES FOURNISSEURS PARTENAIRES : A QUOI SERVENT LES ACCORDS INTER-ENTREPRISES ? UN PARALLELE AVEC LES ROLES DES BUDGETS

International audienceL'objet de cet article est de proposer une lecture des rôles des accords de partenariat industriel au travers de la littérature sur la gestion budgétaire. L'analyse confirme certains rôles proposés par la littérature inter-organisationnelle (notamment par l'approche relationnelle) et fait aussi apparaître plusieurs rôles et inconvénients non abordés jusque là

Management des fournisseurs partenaires: à quoi servent les accords inter-entreprises ? Un parallèle avec les rôles des budgets.

L'objet de cet article est de proposer une lecture des rôles des accords de partenariat industriel au travers de la littérature sur la gestion budgétaire. L'analyse confirme certains rôles proposés par la littérature inter-organisationnelle (notamment ceux de l'approche relationnelle), et fait également apparaître plusieurs rôles et inconvénients non abordés jusque là.The purpose of this article is to explore roles of industrial partnership agreements through the literature about budgets. The analysis confirms the roles proposed by the inter-organizational literature (more specifically by the relational approach) and highlights also roles and drawbacks not that have not been approached yet.roles of budgets; partenariat; accords interentreprises; rôles des budgets; partnership; inter-firms agreements;

Une mine de plomb argentifère dans un environnement montagnard : la mine médiévale du Fournel à L'Argentière-la-Bessée (Hautes-Alpes)

National audienceLa mine d'argent du Fournel a été en activité entre le Xe et le XIVe siècle. Les textes conservés concernent la phase de maturité du XIIe siècle et la phase de ralentissement du milieu du XIIIe siècle. Plusieurs panneaux filoniens ont été exploités à partir d'affleurements, depuis des escarpements rocheux abrupts, jusqu'au fond d'une gorge. La grande dureté de la roche a obligé les mineurs à recourir à l'abattage par le feu. Le relief a grandement facilité la prospection des filons, le démarrage de chantiers à ciel ouvert et l'organisation des exploitations souterraines. Les chantiers s'étendent jusqu'à 150 m du jour et sont assistés par des niveaux de circulation par traînage, des conduits d'aérage perchés en hauteur et des galeries de drainage ouvertes à la base. Ces ouvrages d'assistance reflètent une organisation opportuniste de la mine, facilitée par la topographie et la géologie du gisement. L'analyse sédimentologique et anthracologique des remblais, associée à des expérimentations sérielles, permet de caractériser la chaîne opératoire technique de l'abattage par le feu et son impact sur les modalités de gestion de la forêt arborescente d'altitude, comprimée entre les activités agropastorales et minières

Viscosity and Thermal Conductivity of Stable Graphite Suspensions Near Percolation

Nanofluids have received much attention in part due to the range of properties possible with different combinations of nanoparticles and base fluids. In this work, we measure the viscosity of suspensions of graphite particles in ethylene glycol as a function of the volume fraction, shear rate, and temperature below and above the percolation threshold. We also measure and contrast the trends observed in the viscosity with increasing volume fraction to the thermal conductivity behavior of the same suspensions: above the percolation threshold, the slope that describes the rate of thermal conductivity enhancement with concentration reduces compared to below the percolation threshold, whereas that of the viscosity enhancement increases. While the thermal conductivity enhancement is independent of temperature, the viscosity changes show a strong dependence on temperature and exhibit different trends with respect to the temperature at different shear rates above the percolation threshold. Interpretation of the experimental observations is provided within the framework of Stokesian dynamics simulations of the suspension microstructure and suggests that although diffusive contributions are not important for the observed thermal conductivity enhancement, they are important for understanding the variations in the viscosity with changes of temperature and shear rate above the percolation threshold. The experimental results can be collapsed to a single master curve through calculation of a single dimensionless parameter (a Péclet number based on the rotary diffusivity of the graphite particles).United States. Air Force Office of Scientific Research (FA9550-11-1-0174)National Natural Science Foundation (China) (51036003

Solar steam generation by heat localization

Currently, steam generation using solar energy is based on heating bulk liquid to high temperatures. This approach requires either costly high optical concentrations leading to heat loss by the hot bulk liquid and heated surfaces or vacuum. New solar receiver concepts such as porous volumetric receivers or nanofluids have been proposed to decrease these losses. Here we report development of an approach and corresponding material structure for solar steam generation while maintaining low optical concentration and keeping the bulk liquid at low temperature with no vacuum. We achieve solar thermal efficiency up to 85% at only 10 kW m[superscript −2]. This high performance results from four structure characteristics: absorbing in the solar spectrum, thermally insulating, hydrophilic and interconnected pores. The structure concentrates thermal energy and fluid flow where needed for phase change and minimizes dissipated energy. This new structure provides a novel approach to harvesting solar energy for a broad range of phase-change applications.United States. Dept. of Energy. Office of Basic Energy Sciences (Energy Frontiers Research Center. Award DE-SC0001299)United States. Dept. of Energy. Office of Basic Energy Sciences (Energy Frontiers Research Center. Award DE-FG02-09ER46577))United States. Air Force Office of Scientific Research (FA9550-11-1-0174)Masdar Institute of Science & Technology - MIT Technology & Development ProgramNatural Sciences and Engineering Research Council of Canad

Universal accelerating cosmologies from 10d supergravity

We study 4d Friedmann-Lema\^{i}tre-Robertson-Walker cosmologies obtained from time-dependent compactifications of Type IIA 10d supergravity on various classes of 6d manifolds (Calabi-Yau, Einstein, Einstein-K\"{a}hler). The cosmologies we present are universal in that they do not depend on the detailed features of the compactification manifold, but only on the properties which are common to all the manifolds belonging to that class. Once the equations of motion are rewritten as an appropriate dynamical system, the existence of solutions featuring a phase of accelerated expansion is made manifest. The fixed points of this dynamical system, as well as the trajectories on the boundary of the phase space, correspond to analytic solutions which we determine explicitly. Furthermore, some of the resulting cosmologies exhibit eternal or semi-eternal acceleration, whereas others allow for a parametric control on the number of e-foldings. At future infinity, one can achieve both large volume and weak string coupling. Moreover, we find several smooth accelerating cosmologies without Big Bang singularities: the universe is contracting in the cosmological past ($T0$), while in the vicinity of $T=0$ it becomes de Sitter in hyperbolic slicing. We also obtain several cosmologies featuring an infinite number of cycles of alternating periods of accelerated and decelerated expansions.Comment: v1: 38 pages + appendices, 18 figures; v2-v3: minor modifications and corrected typo

Simulation and Analysis of an Integrated Device to Simultaneously Characterize Thermal and Thermoelectric Properties

For many applications, multiple material properties impact device performance and characterization of multiple properties using a single sample is desirable. In this article, the authors focus on thermoelectric materials characterization, which requires the thermal conductivity, electrical conductivity, and Seebeck coefficient to be quantified. Specifically, the authors present a design analysis using numerical COMSOL simulations of the 3w technique to optimize a measurement structure for thermoelectric films while also including the capability for electrical measurements to be performed on the same sample without detachment or repositioning. Thermal optimization of the structure is achieved through investigation of temperature spatial uniformity, the impact of heater line width on the fitted thermal conductivity, and the impact of uncertainty in material properties and geometric parameters on the fitted thermal conductivities for the material of interest