14 research outputs found
Equation of State of Detonation Products of High Solid Explosives
Le calcul des caractĂ©ristiques de dĂ©tonation dâun explosif solide requiert lâutilisation dâĂ©quations dâĂ©tat pour modĂ©liser le comportement des produits de dĂ©tonation. Cependant, les pressions et les tempĂ©ratures auxquelles sont soumis ces produits rendent difficile la mise au point dâune Ă©quation dâĂ©tat valide de la centaine de kilobars Ă la centaine de bar si lâon souhaite couvrir lâensemble des effets dâune dĂ©tonation. Les nombreuses recherches effectuĂ©es dans ce domaine ont abouti Ă lâĂ©laboration dâun grand nombre dâĂ©quations dâĂ©tat Ă caractĂšre plus ou moins thĂ©orique ou empirique. Malheureusement aucune dâelle ne sâest rĂ©vĂ©lĂ©e ĂȘtre entiĂšrement satisfaisante. Dans ces travaux nous nous intĂ©ressons au domaine de validitĂ© Ă basse pression de lâĂ©quation dâĂ©tat JWL implĂ©mentĂ©e dans les codes dâhydrodynamique et de lâĂ©quation BKW utilisĂ©e dans les codes de thermochimie pour les produits des matĂ©riaux Ă©nergĂ©tiques sous oxygĂ©nĂ©s. La premiĂšre Ă©quation dâĂ©tat considĂšre le mĂ©lange des produits Ă une Ă©chelle macroscopique tandis que la seconde assure une description plus fine du mĂ©lange en considĂ©rant les diffĂ©rentes phases prĂ©sentes. En effet, les produits de dĂ©tonation comprennent en plus des molĂ©cules simples des particules solides de carbone. A cette fin, une Ă©tude numĂ©rique et expĂ©rimentale a Ă©tĂ© menĂ©e pour deux compositions explosives : la Composition B (RDX/TNT) et lâoctoviton (HMX/Viton). Des expĂ©rimentations dâadaptation dâimpĂ©dance entre des matĂ©riaux Ă©nergĂ©tiques et des matĂ©riaux inertes ont Ă©tĂ© rĂ©alisĂ©es afin de dĂ©tendre les produits de dĂ©tonation de la centaine de kilobars Ă quelques bars. Ce dispositif est instrumentĂ© avec des mĂ©trologies innovantes dans le domaine de la dĂ©tonique. La spectromĂ©trie dâĂ©mission ultra rapide est utilisĂ©e pour effectuer lâanalyse spectrale des produits de dĂ©tonation au cours de leur dĂ©tente dans le domaine spectral du visible. Deux signatures thermiques sont identifiĂ©es sur les spectres obtenus : lâune liĂ©e au rayonnement des gaz ionisĂ©s, lâautre liĂ©e au rayonnement des particules solides de carbone. LâinterfĂ©romĂ©trie haute frĂ©quence permet un enregistrement continu de la propagation du choc dans les diffĂ©rents milieux (explosif, matĂ©riau inerte). Ces expĂ©riences font lâobjet de simulations numĂ©riques avec le code dâhydrodynamique Ouranos et le code de thermochimie SIAME du CEA. Les rĂ©sultats expĂ©rimentaux et numĂ©riques concordent jusquâĂ des pressions de lâordre du kilobar. Ces deux mesures permettent dâavancer dans la validation de lâĂ©quation dâĂ©tat des produits de dĂ©tonation implĂ©mentĂ©e dans les codes numĂ©riques.The calculation of detonation characteristics of condensed explosives requires the use of equations of state to model the behavior of the detonation products. However, the extreme pressures and temperatures of these products complicate the development of an equation of state, which is valid from hundreds of kilobars to hundreds of bars range. Numerous investigations in this field have resulted in the development of a large number of theoretical or empirical equations of state. Unfortunately, none of them have been entirely satisfactory. This work addressed the low-pressure range validity of the JWL equation of state and the BKW equation, respectively, used in hydrodynamic codes and the thermochemical codes for the products of energetic materials. The first equation of state considers the mixture of products on a macroscopic scale whereas the second one provides a more detailed description by considering the various phases of the products. The detonation products are composed of simple molecules and solid carbon particles. To this end, a numerical and experimental investigation was undertaken involving two explosive compositions: Composition B (RDX/TNT) and octoviton (HMX/Viton). Impedance matching of energetic materials with inert materials tests were performed to expand the detonation products from a hundred kilobars to a few bars. The setup was instrumented with innovative diagnostics not commonly used in detonation research: ultra-fast emission spectroscopy and high frequency interferometry. The former was used for carrying out the spectral analysis in the visible spectrum range of detonation products during their expansion. Two thermal signatures were identified in the experimental spectra: one associated with radiation from ionised gases, the other with radiation from solid particles of carbon. The latter was used to continuously record shock-wave propagation in the different media (explosive and inert materials). These experiments were simulated using the Ouranos hydrodynamic code and the SIAME thermochemical code from CEA. The experimental and numerical results were in agreement up to pressures of the order of 1 kbar. These measurements offer a set of validation points for the equations of state of detonation products implemented in numerical codes
Ăquations d'Ă©tat des produits de dĂ©tonation des explosifs solides
The calculation of detonation characteristics of condensed explosives requires the use of equations of state to model the behavior of the detonation products. However, the extreme pressures and temperatures of these products complicate the development of an equation of state, which is valid from hundreds of kilobars to hundreds of bars range. Numerous investigations in this field have resulted in the development of a large number of theoretical or empirical equations of state. Unfortunately, none of them have been entirely satisfactory. This work addressed the low-pressure range validity of the JWL equation of state and the BKW equation, respectively, used in hydrodynamic codes and the thermochemical codes for the products of energetic materials. The first equation of state considers the mixture of products on a macroscopic scale whereas the second one provides a more detailed description by considering the various phases of the products. The detonation products are composed of simple molecules and solid carbon particles. To this end, a numerical and experimental investigation was undertaken involving two explosive compositions: Composition B (RDX/TNT) and octoviton (HMX/Viton). Impedance matching of energetic materials with inert materials tests were performed to expand the detonation products from a hundred kilobars to a few bars. The setup was instrumented with innovative diagnostics not commonly used in detonation research: ultra-fast emission spectroscopy and high frequency interferometry. The former was used for carrying out the spectral analysis in the visible spectrum range of detonation products during their expansion. Two thermal signatures were identified in the experimental spectra: one associated with radiation from ionised gases, the other with radiation from solid particles of carbon. The latter was used to continuously record shock-wave propagation in the different media (explosive and inert materials). These experiments were simulated using the Ouranos hydrodynamic code and the SIAME thermochemical code from CEA. The experimental and numerical results were in agreement up to pressures of the order of 1 kbar. These measurements offer a set of validation points for the equations of state of detonation products implemented in numerical codes.Le calcul des caractĂ©ristiques de dĂ©tonation dâun explosif solide requiert lâutilisation dâĂ©quations dâĂ©tat pour modĂ©liser le comportement des produits de dĂ©tonation. Cependant, les pressions et les tempĂ©ratures auxquelles sont soumis ces produits rendent difficile la mise au point dâune Ă©quation dâĂ©tat valide de la centaine de kilobars Ă la centaine de bar si lâon souhaite couvrir lâensemble des effets dâune dĂ©tonation. Les nombreuses recherches effectuĂ©es dans ce domaine ont abouti Ă lâĂ©laboration dâun grand nombre dâĂ©quations dâĂ©tat Ă caractĂšre plus ou moins thĂ©orique ou empirique. Malheureusement aucune dâelle ne sâest rĂ©vĂ©lĂ©e ĂȘtre entiĂšrement satisfaisante. Dans ces travaux nous nous intĂ©ressons au domaine de validitĂ© Ă basse pression de lâĂ©quation dâĂ©tat JWL implĂ©mentĂ©e dans les codes dâhydrodynamique et de lâĂ©quation BKW utilisĂ©e dans les codes de thermochimie pour les produits des matĂ©riaux Ă©nergĂ©tiques sous oxygĂ©nĂ©s. La premiĂšre Ă©quation dâĂ©tat considĂšre le mĂ©lange des produits Ă une Ă©chelle macroscopique tandis que la seconde assure une description plus fine du mĂ©lange en considĂ©rant les diffĂ©rentes phases prĂ©sentes. En effet, les produits de dĂ©tonation comprennent en plus des molĂ©cules simples des particules solides de carbone. A cette fin, une Ă©tude numĂ©rique et expĂ©rimentale a Ă©tĂ© menĂ©e pour deux compositions explosives : la Composition B (RDX/TNT) et lâoctoviton (HMX/Viton). Des expĂ©rimentations dâadaptation dâimpĂ©dance entre des matĂ©riaux Ă©nergĂ©tiques et des matĂ©riaux inertes ont Ă©tĂ© rĂ©alisĂ©es afin de dĂ©tendre les produits de dĂ©tonation de la centaine de kilobars Ă quelques bars. Ce dispositif est instrumentĂ© avec des mĂ©trologies innovantes dans le domaine de la dĂ©tonique. La spectromĂ©trie dâĂ©mission ultra rapide est utilisĂ©e pour effectuer lâanalyse spectrale des produits de dĂ©tonation au cours de leur dĂ©tente dans le domaine spectral du visible. Deux signatures thermiques sont identifiĂ©es sur les spectres obtenus : lâune liĂ©e au rayonnement des gaz ionisĂ©s, lâautre liĂ©e au rayonnement des particules solides de carbone. LâinterfĂ©romĂ©trie haute frĂ©quence permet un enregistrement continu de la propagation du choc dans les diffĂ©rents milieux (explosif, matĂ©riau inerte). Ces expĂ©riences font lâobjet de simulations numĂ©riques avec le code dâhydrodynamique Ouranos et le code de thermochimie SIAME du CEA. Les rĂ©sultats expĂ©rimentaux et numĂ©riques concordent jusquâĂ des pressions de lâordre du kilobar. Ces deux mesures permettent dâavancer dans la validation de lâĂ©quation dâĂ©tat des produits de dĂ©tonation implĂ©mentĂ©e dans les codes numĂ©riques
SYNDROME DES BRIDES AMNIOTIQUES (REVUE DE LA LITTERATURE, ETUDE D'UNE SERIE DE 68 CAS SUIVIS ET TRAITES SUR 35 ANS)
AIX-MARSEILLE2-BU MĂ©d/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF
Static and Dynamic Permittivity Measurement of High Explosives in the W Band to Investigate Shock and Detonation Phenomena
International audienceRadio interferometry techniques are often used to investigate shock and detonation phenomena thanks to the radioâtransparency of high explosives in the gigahertz frequency band. These techniques require the knowledge of the permittivity of studied explosives. Although the permittivity has been thoroughly studied for many materials, very few data are available at high frequencies (>75â
GHz) for high explosives. In this paper, we report static measurement data of the permittivity for various reactive materials using the standard line transmission method between 75â
GHz and 110â
GHz (W frequency Band), and we present dynamic measurement results at 94â
GHz obtained from the soâcalled detonation wavefront tracking method. It is shown that the measurement results provided by these two methods are in good agreement. As a consequence, this work validates the detonation wavefront tracking method for the dynamic measurement of high explosives permittivity, and shows that the static experimental results are relevant for shock wave propagation analysis from millimeterâwave measurement techniques
Heterotopic implantation of amputated digits following constriction ring syndrome: AÂ case series
Investigation of JWL Equation of State for Detonation Products at Low Pressure With Radio Interferometry
International audienceA thermochemical code, SIAME, dedicated to the study of high explosives, is currently being validated. From this code, both the parameters of the JWL equation of state of a given composition are calibrated from the calculated adiabatic curve and tabulated equations of state are constructed. SIAME code uses BKW equations with a specific calibration presented in this study. Calculated adiabatic curves are compared with the one obtained with the American code CHEETAH with the BKWC, BKWS and EXP6 calibrations for two different high explosive formulations: a meltâcast one (RDX/TNT 60/40â%âwt.) and a pressed one (HMX/Viton 96/4â%âwt.). The validity of the constant entropy curves obtained with the JWL EOS and the tabulated EOS is investigated from the ChapmanâJouguet state to several dozens of megapascals to cover all the high explosive effects. Experimental results obtained for the two high explosives with the cylinder test and the impedance matching test are presented in this study and offer a set of validation points
How much can air conditioning increase air temperatures for a city like Paris, France?
International audienc
Influence of air conditioning management on heat island in Paris air street temperatures
International audienceProjections of future climate suggest increases in extreme temperatures particularly in mid latitudes. In addition, the effect of heat waves, which are becoming a major âsummer killerâ, is exacerbated in urban areas owing to the heat island effect. Air conditioning (A/C) is a key parameter for health problems in case of heat waves since, on one hand, it reduces mortality but, on the other hand, depending on the heat management, it can increase street temperature therefore increasing the air cooling demand. Results of a meso-scale meteorological model (MESO-NH), coupled to an urban energy balance model including a simplified building model (TEB), are used. Simulations based on a realistic spatial cartography of air-cooled chillers and cooling towers in the city of Paris and surroundings have been performed. The simulation period corresponds to the extreme heat wave in Paris: 9â13 August 2003. Five scenarios will be discussed: firstly a baseline without air-conditioning (NO-AC scenario); secondly the actual situation including individual air dry coolers, wet cooling towers and an urban cooling network relying on free-cooling (water-cooled A/C with the river Seine) (REAL scenario). A third scenario will assume that all the heat is rejected as sensible heat in the atmosphere (DRY AC scenario). Two other scenarios correspond to a prospective where A/C is doubled. Scenario 4 assumes that all the heat is rejected as sensible heat in the atmosphere (DRY ACx2 scenario). On the opposite, scenario 5 assumes that all the heat is rejected underground or in the river Seine (NOREJ scenario). Results show that A/C affects the UHI depending on its management. A detailed analysis on selected districts shows that the local temperature variation resulting from heat island is proportional to the sensible heat rejected locally by A/C, indicating that a clever A/C management is all the more important to provide comfort and to mitigate heat island. Moreover, the incidence of the sky view factor is also discussed