158 research outputs found

    Community-based management of cultivated biodiversity - A French initiative on forage crops to design agro-ecological systems

    Get PDF
    The over-simplification of modern intensive agro-ecosystems in terms of cultivated biodiversity had dramatically increased their vulnerability to stresses and perturbations. In order to create and use a higher specific and genetic diversity several community management seed systems (or “Seed Houses”) are being currently set up in France. In this country where most farmers are used to buying commercial seeds, these initiatives are considered innovative. They also raise several issues such as: how to obtain, improve and conserve adapted plant genetic resources? How farmers’ communities can organise themselves to produce and exchange seeds amongst their members? Which procedures, which quality thresholds, which skills and which tools must be developed? With the aim to finding solutions the participatory research project entitled “ProABiodiv” involving farmers, extension services and researchers in genetics, sociology and economy was set up in 2011 on forage crops. It is a good illustration of how we can bridge the gap between scientific knowledge and the know-how of practitioners. Solutions must be locally developed as they are connected to a specific background, producing outputs that guide practitioners in raising the relevant questions rather than providing recipes

    La programmation en Junior

    Get PDF
    {\Junior est un langage construit au dessus de Java pour programmer des comportements réactifs. Il autorise la concurrence, les événements diffusés et définit plusieurs primitives permettant d'obtenir un contrôle fin sur l'exécution des programmes réactifs. Il est utilisé au travers d'une API, nommée Jr, qui masque les implémentations existantes

    Distributed Reactive Machines

    Get PDF
    One considers systems made of synchronizers to which distributed reactive machines are connected. The corresponding model is described with its implementation in Java, using SugarCubes and the RMI mechanism

    The Junior Reactive Kernel

    Get PDF
    We define Junior as a Java framework kernel for reactive programming with broadcast events. We give Junior a formal semantics based on rewriting rule. We also describe three implementations of Junior. The first one, called REWRITE, is the direct implementation of the semantics rules. The second one is called REPLACE; it is more efficient than REWRITE as it reuses Java objects instead of always creating new ones. The third implementat- ion, called TURBO, optimises the number of syntax tree traversals and is adapted to situations where there are a large number of events. Finally, we discuss the extension of Junior to distributed contexts and compare it with the SugarCubes Reactive Java framework

    CLIMAGIE: A French INRA Project to Adapt the Grasslands to Climate Change

    Get PDF
    Climate change in France, central and southern Europe is expected to provoke more frequent and more intense summer water deficits, with increased amplitude in temperatures, exposing the same perennial crops to frosts as well as to heat waves and severe droughts. The impacts on sown monospecific grasslands have been assessed using crop models (Durand et al. 2010) but with less accuracy in extreme situations. Since less work has been done on intra-specific genetic variability there is urgent need to investigate both ranges of climate conditions and genetic variability (Poirier et al. 2012). Phenology and plant productivity responses to water, temperature and nitrogen (N) in particular need to be re-assessed over the full range of temperatures projected in the future

    Scattering in a partially open waveguide: the forward problem

    Get PDF
    This paper is dedicated to an acoustic scattering problem in a two-dimensional partially open waveguide, in the sense that the left part of the waveguide is closed, that is with a bounded crosssection, while the right part is bounded in the transverse direction by some Perfectly Matched Layers that mimic the situation of an open waveguide, that is with an unbounded cross-section. We prove well-posedness of such scattering problem and exhibit the asymptotic behaviour of the solution in the longitudinal direction with the help of the Kondratiev approach. Having in mind the numerical computation of the solution, we also propose some transparent boundary conditions in such longitudinal direction, based on Dirichlet-to-Neumann operators. After proving that such artificial conditions actually enable us to approximate the exact solution, some numerical experiments illustrate the quality of such approximation

    Study of High-Performance Engineering Polymers Applied In Reciprocating Hermetic Refrigeration Compressors

    Get PDF
    Manufacturers of hermetic refrigeration compressors for domestic and commercial applications have been increasing the energy efficiency of their products systematically over the last decades through the continuous efforts of in-house research groups, universities and suppliers. This joint effort encompasses the technical fields of design, materials, processes, manufacturing, and simulation techniques, to achieve a multidisciplinary approach to compressor optimization as applied to refrigeration systems. Gains such as increased efficiency of the electric motor, reduction of bearing friction power loss, minimizing back flow on valves have already been addressed and the continuous search for new approaches have been proposed. This work presents a study of energy efficiency gain by comparing low conduction heat transfer plastic materials to metallic materials used in current compressor designs. The components compared include the cylinder head, discharge muffler, shock loop, valve plate and crankcase. The energy efficiency gain was evaluated using the Coefficient of Performance (COP) through the use of the Conjugate Heat Transfer (CHT) model using superheating temperature. The CHT model temperature results were compared with the values measured by an instrumented compressor. To complement the study, the parts and assemblies were structurally evaluated using the finite element method under performance and durability test operating conditions. The feasibility of the mold filling process was verified, because the final design of the components must be a compromise between functional requirements and process solution. In conclusion, the results show that significant efficiency gains can be achieved through the use of engineering thermoplastic. This is achieved through careful material selection and proper design that considers not only material properties, but material and process costs using the flexibility of injection molding to group parts and subsystems

    Spectroscopy of BL Lac Objects: new redshifts and mis-identified sources

    Get PDF
    We are carrying out a program of high signal to noise optical spectroscopy of BL Lacs with unknown or tentative redshift. Here we report some preliminary results. New redshifts are measured for PKS0754+100 (z=0.266) and 1ES0715-259 (z=0.464) . From lineless spectra of PG1553+113 and PKS1722+119 we set a lower limit of z>0.3 for both sources. In two cases (UM493 and 1620+103) stellar spectra indicate a wrong classification.Comment: 4 pages; Conference proceeding "High Energy Blazar Astronomy", Tuorla Observatory, Finland, 17-21 June 2002; to be published in the PASP conference serie

    Obscured Activity: AGN, Quasars, Starbursts and ULIGs observed by the Infrared Space Observatory

    Full text link
    Some of the most active galaxies in the Universe are obscured by large quantities of dust and emit a substantial fraction of their bolometric luminosity in the infrared. Observations of these infrared luminous galaxies with the Infrared Space Observatory (ISO) have provided a relatively unabsorbed view to the sources fuelling this active emission. The improved sensitivity, spatial resolution and spectroscopic capability of ISO over its predecessor Infrared Astronomical Satellite (IRAS), has enabled significant advances in the understanding of the infrared properties of active galaxies. ISO surveyed a wide range of active galaxies which, in the context of this review, includes those powered by intense bursts of star-formation as well as those containing a dominant active galactic nucleus (AGN). Mid infrared imaging resolved for the first time the dust enshrouded nuclei in many nearby galaxies, while a new era in infrared spectroscopy was opened by probing a wealth of atomic, ionic and molecular lines as well as broad band features in the mid and far infrared. This was particularly useful since it resulted in the understanding of the power production, excitation and fuelling mechanisms in the nuclei of active galaxies including the intriguing but so far elusive ultraluminous infrared galaxies. Detailed studies of various classes of AGN and quasars greatly improved our understanding of the unification scenario. Far-infrared imaging and photometry also revealed the presence of a new very cold dust component in galaxies and furthered our knowledge of the far-infrared properties of faint starbursts, ULIGs and quasars. We summarise almost nine years of key results based upon ISO data spanning the full range of luminosity and type of active galaxies.Comment: Accepted for publication in 'ISO science legacy - a compact review of ISO major achievements', Space Science Reviews - dedicated ISO issue. To be published by Springer in 2005. 62 pages (low resolution figures version). Higher resolution PDFs available from http://users.physics.uoc.gr/~vassilis/papers/VermaA.pdf or http://www.iso.vilspa.esa.es/science/SSR/Verma.pd
    • …
    corecore