Search results for "Thermique"
showing 10 items of 40 documents
Radiative surface temperature and convective flux calculation over crop canopies
1988
The analysis presented in this paper aims at a better understanding of the potential role of radiative temperature, as measured by a radiometer over crops, in sensible heat flux calculation. Defining radiative temperature as the mean temperature of the surfaces viewed by the radiometer (leaves and soil surface) and assuming that an Ohm's law type formula can be used to express sensible heat flux as a function of the difference between air temperature and radiative temperature, the aerodynamic resistance which divides this temperature difference has been analytically defined. The parameters which appear in the resistance expression depend essentially on wind velocity and canopy structure but…
Etude par analyse thermique différentielle des tranformations de phases sur l'iodate de lithium
1986
International audience; Lithium iodate (LiIO3) exists at room temperature either as hexagonal (alpha) or tetragonal (beta) crystals. Beta-LiIO3 is stable up to the melting point, whereas alpha-LiIO3 is known to undergo phase transitions. We have studied by differential thermal analysis (DTA) the sequence of phase transitions occurring on powders prepared by different processes. An alpha-LiIO3 powder obtained by grinding a single crystal exhibits the well-known transformations alpha-gamma-beta. A powder obtained by fast evaporation of an aqueous solution transforms directly the alpha to the beta and does not exhibit any intermediate gamma phase. Further, DTA investigations point out that the…
Comportement en fatigue thermomécanique à haute température d’un système barrière thermique texturé par laser
2020
In service life of Thermal Barrier Coating (TBC) systems for blade applications can be limited by the top-coat (TC) spallation under thermo-mechanical fatigue (TMF) loadings. To improve its TMF life, laser texturing at the bond-coat/top coat interface in the CMSX-4 Plus / γ-γ’ BC/ EB-PVD TC system has been investigated.Thanks to the study of the laser-matter interaction, it seems that the different Ni-based single crystal superalloys have similar laser ablation behaviors and they present almost no sub-surface damage after ablation. Nevertheless, the formation of melted matter near created cavities, possibly recrystallized, is often observed.Different patterns (holes, lines, grids) have been…
Contribution to the study and to the optimization of active thermographic process applied to surface crack detection
2017
The aim of this work is the detection of open and subjacent defects in metallic materials using laser-material interaction coupled with infrared thermography. This process is a possible alternative for magnetic particles testing and dye penetrant testing in the field of non-destructive testing. This work is divided into three main parties. At first, we have been interested in the characterization of optical and thermophysical properties of materials we used, in order to have good boundary conditions and also for the needs of temperatures fields measurements for validation. The second part concern the development of a numerical simulation model with two step approach: the first involves mode…
Impacts of climate change on the performance of an insect pest and associated consequences for tritrophic interactions
2019
Global warming poses a major challenge to living organisms, particularly for ectothermic animals like insects, whose physiology and behaviour are closely related with direct thermal surroundings. This thesis aims at experimentally investigating the impacts of climate change on the overall performance of a major grapevine pest, the European grapevine moth (Lobesia botrana), and the associated consequences for interactions involving this phytophagous insect and adjacent trophic levels, more specifically natural enemies (parasitoids). The experiments conducted focus on three facets of climate change: an increase in mean temperature, an alteration of daily thermal range, and the occurrence of h…
Adaptation to climate change of the French wine industry: a systemic approach – Main outcomes of the project LACCAVE
2018
Présenté au 12. Congreso Internacional Terroir; Taking into account the major economical role and specificities of the French wine industry, adaptation to climate change is a very challenging issue. In 2011, 23 research teams launched a systemic and multidisciplinary program to analyze the impacts from the vine to the region, to define adaptation strategies combining technical, spatial and organizational options and to evaluate the perception by the actors and consumers of climate change issues. Thermal variability was studied at local scale to develop high resolution atmospheric models which better simulate future climate trends. Impacts on growth/developmental conditions and vine response…
Dynamique spatio-temporelle d’un événement extrême froid : impact de la circulation atmosphérique sur les basses températures en Bourgogne viticole.
2020
During April 2019 France experienced several frost events that caused extensive damage to almost all of its winegrowing regions. In Bourgogne-Franche-Comté the frost effects were very punctual and spatially diffused, the greatest damage being observed in the early bud breaking winegrowing sub-regions of Saône-et-Loire and the south of the Côte de Beaune. This study focuses on the multi-scalar analysis of the spring frost event underwent during the night between the 4th and 5th of April on a vineyard plot located in the Hautes Côtes de Beaune appellation. The analysis highlights the impact of local parameters (topography, surface discontinuity, etc.) on the spatio-temporal structuring of tem…
THERMIDE : un programme de recherche pour optimiser les opérations de mise en forme et de traitements thermiques de composants métalliques
2011
Colloque Matériaux et mise en forme des composants de centrales nucléaires; National audience; L'objectif du programme THERMIDE est d'optimiser le procédé de fabrication des composants métalliques par une meilleure maîtrise des déformations et le contrôle de la taille de grain. Devant la complexité du problème, une attention particulière est portée à la modélisation de la recristallisation dynamique activée durant la déformation à chaud des métaux. Les applications portent sur différentes nuances d'acier pour composants nucléaires ainsi qu'un matériau " école " (le tantale). La simulation d'un traitement thermique est également abordée dans l'intention de valider le logiciel FORGE®.
Etude comparative de deux méthodes de transformation et de deux milieux de culture chez Agrobacterium tumefaciens souche LBA4404
2013
Rapport de stage de master 1 BAP GEAPSI
Contribution to the study of the recovery of wast heat : study and optimization of Stirling engines
2012
Several machines currently used, internal combustion engines for the car industry or thermal power plants in energy, exhaust a considerable amount of heat. Generally this heat is dispersed in the atmosphere and its energy lost. So we took a special interest in external heat engines which primary energy is heat energy, and more particularly in Stirling engines. One of its main characteristics is the used of energy from heat produced externally like energy source. This allows Stirling engines to be multi-fuel and even to use natural heat energy.The study carried out is made up of two parts. First, a three zones zero dimensional finite-time thermodynamic model has been developed. It takes into…