Дисертації з теми "Shock Pad"
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Scott, Michael Brian. "General relativistic shock-waves propagating at the speed of light /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
Повний текст джерелаHamdoun, Amro M. "Molecular physiology of stress tolerance in marine invertebrates : the heat shock response and multidrug resistance /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Повний текст джерелаBrahmi, Nassim. "Etude numérique de la propagation et l’atténuation des ondes de choc en milieux confinés Turbulent structures of shock-wave diffraction over 90° convex corner Analysis of shock-wave diffraction over double concave cylindrical wedges. Part I: Shock dynamics Analysis of shock-wave diffraction over double cylindrical wedges. Part II: Vorticity generation Achieving an optimal shock-wave mitigation inside open channels with cavities for weak shock waves: a computational study." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR09.
Повний текст джерелаThe propagation of shock waves involves complex interactions between waves and surrounding media, which gives rise to several phenomena such as reflection, diffraction, etc. To shed more light into the fundamental physics associated with these phenomena, high resolution numerical simulations were carried out. In particular, analysis of shock diffraction over double concave cylindrical wedges revealed that the transition angles, from regular to Mach reflection, increase with the Mach number, whereas they are found to be almost the same over the two concave surfaces for the transonic Mach regimes and relatively larger on the second surface for high ones showing that the flow is capable of retaining the memory of the past events over the entire process for the high Mach numbers. The analysis of the vorticity equation balance showed, for the first time, that the diffusion of the vorticity due to the viscous effects is quite important compared to the baroclinic term for low Mach numbers, while this trend is inverted for higher Mach numbers. The study also showed that the stretching of the vorticity due to the compressibility effects plays an important role in the vorticity production. On the basis of these numerical simulations, an approximate universal relation is proposed, allowing to predict the incident-shock trajectory and velocity as a function of the incident-shock Mach number, the radius of curvature of the geometry, and the gas properties. Afterward, the study of shock-waves propagation and their attenuation in channel flow having different heights and exhibiting a hollow circular cavities with different depths has been clone. The results also showed the importance of reducing the height of the channel and changing the position of the reduced section in addition to the diffraction angle and the cavity depth for better shock-waves attenuation. A subtle arrangement of channel position/height and a cavity location/depht was found
Vallet, Alexandra. "Hydrodynamic modelling of the shock ignition scheme for inertial confinement fusion." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0214/document.
Повний текст джерелаThe shock ignition concept in inertial confinement fusion uses an intense power spike at the end of an assembly laser pulse. the key feature of shock ignition are the generation of a high ablation pressure, the shock pressure amplification by at least a factor of a hundred in the cold fuel shell and the shock coupling to the hot-spot. in this theses, new semi-analytical hydrodynamic models are developed to describe the ignitor shock from its generation up to the moment of fuel ignition. A model is developed to describe a spherical concerging shock wave in a pre-heated hotspot. The self-similar solution developed by Guderley is perturbed over the shock Mach number Ms >>1. The first order correction accounts for the effects of the shock strength. An analytical ignition criterion is defined in terms of the shock strength ans th hot-spot areal density. The ignition threshold is higher when the initial Mach number of the shock is lower. A minimal shock pressure of 20 Gbar is needed when it enters the hot-spot. The shock dynamics in the imploding shell is the analyzed. The shock is propagating into a non inertial medium with a high radial pressure gradient and an averall pressure increase with time. The collision with a returning shock coming from the assembly phase enhances further the ignitor shock pressure. The analytica theory allows to des cribe the shock pressure and strength evolution in a typical shock ignition implosion. It is demonstrated that, in the case of the HiPER target design, a generation shock pressure near the ablation zone on the order of 300-400 Mbar is needed. An analysis of experiments on the strong shock generation performed on the OMEGA laser facility is presented. It is sown that a shock presssure close to 300 Mbar near the ablation zone has been reached with an absorbed laser intensity up to 2 x 10(15) W:cm-2 and a laser wavelength of 351 nm. This value is two times higher than the one expected from collisional laser absorption only. That significant pressure enhancement is explained by contribution of hot-electrons generated by non-linear laser/plasma interaction in the corona. The proposed analytical models allow to optimize the shock ignition scheme, including the inuence of the implosion parameters. Analytical, numerical and experimental results are mutualy consistent
Giral, Pérez Marta. "Estudio del efecto de los antagonistas del factor activador de las plaquetas (PAF) en varios modelos de shock experimental." Doctoral thesis, Universitat Autònoma de Barcelona, 1997. http://hdl.handle.net/10803/5367.
Повний текст джерелаOtro importante modelo es el shock endotóxico, inducido en la rata por la administración de lipopolisacárido (LPS) de E. coli de diversos serotipos. El serotipo 0111:B4 produce un característico efecto bifásico de hipotensión arterial. El UR-12460 no inhibe la profunda e inmediata fase de hipotensión pero sí la segunda fase, más lenta y progresiva. Utilizando el serotipo 0127:B8 se ha estudiado el aumento de permeabilidad vascular en la rata. Se ha comprobado que sólo algunos órganos resultan afectados significativamente y que el aumento de permeabilidad se aprecia a partir de los 15 minutos de administrado el LPS. Por otra parte, hay una buena correlación entre la inhibición de la mortalidad inducida por PAF y la inducida por LPS en ratón, lo que refuerza la participación del PAF como mediador clave en la cascada de acontecimientos que producen la mortalidad por LPS. Este papel queda reforzado por la eficacia mostrada por el UR-12460 al atenuar las alteraciones bioquímicas y enzimáticas inducidas por LPS en rata. La inhibición del aumento del tiempo parcial de tromboplastina activada indica que el PAF puede estar también implicado en los mecanismos que conducen al síndrome de coagulación intravascular diseminada en la rata. El último modelo estudiado es el shock hipovolémico hemorrágico, en el cual la eficacia de los antagonistas probados no se ha demostrado. Es posible que su administración sólo sea beneficiosa en fases iniciales de la hemorragia, cuando el shock no se ha hecho todavía progresivo o no se han liberado otros mediadores.
En resumen, puede decirse que el UR-12460 se ha mostrado activo, al menos parcialmente, en varios modelos de shock, reforzando la idea de la participación importante del PAF en estos procesos de tan diversa etiología. Sin embargo, el hecho de que este compuesto no tenga efecto sobre algunos de los marcadores del shock estudiados hace pensar que el futuro de un posible tratamiento del shock pasaría por la administración conjunta de diferentes sustancias, dirigidas cada una a los diferentes mediadores del shock que, además del PAF, intervienen en mayor o menor grado en su etiopatogenia.
Shock is a clinical situation that has been observed for centuries and whose presence has been associated to processes leading usually to death. The study of these processes has allowed to reach the conclusion that shock is a multifactorial and multietiological component syndrome. Since the cascade of events that take place during shock is very complex, it seems unlikely that acting on a single of its steps may be sufficient to block the shock state in its entirety. Nevertheless, in the last years different therapeutic approaches are being studied, among them the antagonism of platelet activating factor (PAF). The different studies carried out in this thesis intend to be a contribution to the study of the role of PAF and of its antagonists in shock. With a view to this we have performed several experimental models, both in vitro and in vivo, using UR-12460, a potent and selective PAF antagonist. The studied models are: anaphylactic shock, splachnic and coronary ischemia-reperfusion-induced shock, endotoxic shock and hemorrhagic shock. UR-12460 was found to be effective in active anaphylactic shock models, both in guinea pigs and mice. Furthermore, for a series of PAF antagonists, we have observed a good correlation between the inhibition of PAF-induced mortality and of active anaphylactic shock -induced mortality in mice, which indicates that PAF is involved in these processes. The ineffectiveness of UR-12460 in passive shock processes suggests a minor relative importance of PAF with respect to other mediators such as histamine. On the other hand, in splachnic ischemia-reperfusion (ischemia-reperfusion) shock models in the rat, UR-12460 has been shown partially effective, inhibiting the mortality and thrombocytopenia induced by shock. Another model of ischemia-reperfusion, but at myocardial level in this case, has been extensively studied in the rat. The occlusion during 6 minutes of the left coronary artery in the anesthetized rat, and subsequent reperfusion during 10 minutes, produces a number of disturbances in cardiac rhythm that are inhibited by UR-12460. This compound reduces the incidence of ventricular tachycardia during the occlusion phase as well as the onset of ventricular fibrillation in the reperfusion. This finding supports the role of PAF in the arrhythmogenesis by ischemia-reperfusion. The ischemia-reperfusion tests in isolated rat heart using the Langendorff method, combined with the subsequent incubation of the cardiac tissue with triphenyltetrazolium chloride, allow to combine in a single experiment, and under identical conditions, the macroscopic assessment of the infarcted area and the functional alterations of the heart. In this model, hearts are perfused with blood diluted with Krebs solution and are compared with hearts receiving only Krebs. The marked differences observed between the ischemic hearts that have received diluted blood and those that have not suggest that blood cells are a key factor in the genesis of infarction and in the impairment of cardiac function. On the other hand, the absence of a direct relationship between the time of ischemia-reperfusion and the severity of the infarction in the absence of blood suggests that the situation of anoxia is not a relevant factor in the genesis of infarction. There is indeed a relationship between the time of ischemia-reperfusion and the impairment of the mechanical function. The presence of blood cells may represent an amplification system of the damage caused by the anoxia. The results obtained in this model with the compound UR-12460 and the antioxidant mercaptopropionylglycine suggest that both PAF antagonism and free radical scavenging may be useful to reduce infarction and, in general, to improve the myocardial function during reperfusion and to reduce arrhythmias.
Another important model is the endotoxic shock, which is induced in the rat by the administration of E. coli lipopolysaccharide (LPS) of different serotypes. Serotype 0111:B4 produces a characteristic biphasic effect of arterial hypotension. UR-12460, although not able to inhibit the steep and immediate phase of hypotension, clearly inhibits the second phase, which is slower and more progressive. The increase in vascular permeability has been studied in the rat using serotype 0127:B8. We have observed that only some organs are significantly affected and that the increase in permeability is noticeable from 15 minutes post-administration of LPS. UR-12460 has been shown to inhibit extravasation in the trachea and seminal vesicle. On the other hand, we have observed a good correlation between the inhibition of the mortality induced by PAF and that induced by LPS in the mouse, which fact reinforces the involvement of PAF as a key mediator in the cascade of events that cause the mortality by LPS. This is additionally supported by the ability shown by UR-12460 to reduce the biochemical and enzymatic alterations induced by LPS in the rat. The inhibition of the increase in the activated partial thromboplastin time shows that PAF may also be involved in the mechanisms leading to disseminated intravascular coagulation syndrome in the rat. The last shock model we have studied is the hemorrhagic hypovolemic shock, where none of the antagonists tested has proved effective. It is possible that their administration may only be beneficial in the initial stages of hemorrhage, when shock has not yet become progressive or other mediators have not yet been released.
To sum up, it can be said that UR-12460 has proved effective, at least partially, in several models of shock, reinforcing the theory that PAF has a key role in these processes of such diverse etiology. However, the fact that this compound has no effect on some of the shock markers studied in this thesis brings us to think that the future of a possible treatment for shock requires the administration of different substances, directed to each one of the different mediators of shock that, in addition to PAF, are involved to a greater or lesser extent in its etiopathogenesis.
Haj, Montaser A. "The influence of neutrophils and mononuclear leucocytes on the fibrinolytic response to severe sepsis." Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295797.
Повний текст джерелаShin, Hyung-Cheol. "Determinants of an optimal exchange rate regime : production composition, economic size, shock structure, consumption habits, and presence of "original sin" /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Повний текст джерелаFang, Lin. "Mechanism of client protein binding by heat shock protein 90 /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251819301&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Повний текст джерелаTypescript. Includes vita and abstract. Includes bibliographical references (leaves 115-121). Also available for download via the World Wide Web; free to University of Oregon users.
Llor, Aisa Emma. "Génération de très hautes pressions d'ablation laser et de chocs forts pour l'allumage des réactions de fusion nucléaire." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0013/document.
Повний текст джерелаThe Shock Ignition (SI) scheme is a promising approach to obtaining energy on alarge scale. However, this scheme needs ablation pressures in the range of 300-400Mbar to reach ignition. The objective of this thesis is therefore to better understandthe underlying physics of high pressure generation by energetic electrons in a regimeof intensity between one and ten petawatt per cm2. In this thesis, a model hasbeen established for calculating the shock pressure generated by hot electrons andthe time of its formation for an arbitrary electron energy distribution and plasmadensity profile. It is shown that a broader electron energy distribution leads to amore homogeneous energy deposition which implies a longer shock time formationand a reduction of the shock strength. These consequences should be taken intoaccount in shock ignition target design. The extension of this model to the case ofa inhomogeneous plasma shows that the low density corona decreases fast electrons energy and then the amount of energy deposited in the compressed target. This leads to a reduction of the time needed for the shock formation, of the shock pressure and the energy invested in the shock. This theoretical model allows us to interpret the experiment performed in spherical geometry on the OMEGA laser facility. The comparison between numerical simulations and experimental results allow us to characterize the electron source as well as shock pressure and dynamic. Finally, we propose a preliminary design of an experiment to explore the hot electron role in shock generation in planar geometry on the LMJ-PETAL laser facility
Ramey, Christopher Shane. "Post-transcriptional adaptation of Escherichia coli during the cold shock response." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1464111681&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Повний текст джерелаBen, Hassan Saïdi Ismaïl. "Numerical simulations of the shock wave-boundary layer interactions." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS390/document.
Повний текст джерелаSituations where an incident shock wave impinges upon a boundary layer are common in the aeronautical and spatial industries. Under certain circumstances (High Mach number, large shock angle...), the interaction between an incident shock wave and a boundary layer may create an unsteady separation bubble. This bubble, as well as the subsequent reflected shock wave, are known to oscillate in a low-frequency streamwise motion. This phenomenon, called the unsteadiness of the shock wave boundary layer interaction (SWBLI), subjects structures to oscillating loads that can lead to damages for the solid structure integrity.The aim of the present work is the unsteady numerical simulation of (SWBLI) in order to contribute to a better understanding of the SWBLI unsteadiness and the physical mechanism causing these low frequency oscillations of the interaction zone.To perform this study, an original numerical approach is used. The one step Finite Volume approach relies on the discretization of the convective fluxes of the Navier Stokes equations using the OSMP scheme developed up to the 7-th order both in space and time, the viscous fluxes being discretized using a standard centered Finite-Difference scheme. A Monotonicity-Preserving (MP) constraint is employed as a shock capturing procedure. The validation of this approach demonstrates the correct accuracy of the OSMP scheme to predict turbulent features and the great efficiency of the MP procedure to capture discontinuities without spoiling the solution and with an almost negligible additional cost. It is also shown that the use of the highest order tested of the OSMP scheme is relevant in term of simulation time and accuracy compromise. Moreover, an order of accuracy higher than 2-nd order for approximating the diffusive fluxes seems to have a negligible influence on the solution for such relatively high Reynolds numbers.By simulating the 3D unsteady interaction between a laminar boundary layer and an incident shock wave, we suppress the suspected influence of the large turbulent structures of the boundary layer on the SWBLI unsteadiness, the only remaining suspected cause of unsteadiness being the dynamics of the separation bubble. Results show that only the reattachment point oscillates at low frequencies characteristic of the breathing of the separation bubble. The separation point of the recirculation bubble and the foot of the reflected shock wave have a fixed location along the flat plate with respect to time. It shows that, in this configuration, the SWBLI unsteadiness is not observed.In order to reproduce and analyse the SWBLI unsteadiness, the simulation of a shock wave turbulent boundary layer interaction (SWTBLI) is performed. A Synthetic Eddy Method (SEM), adapted to compressible flows, has been developed and used at the inlet of the simulation domain for initiating the turbulent boundary layer without prohibitive additional computational costs. Analyses of the results are performed using, among others, the snapshot Proper Orthogonal Decomposition (POD) technique. For this simulation, the SWBLI unsteadiness has been observed. Results suggest that the dominant flapping mode of the recirculation bubble occurs at medium frequency. These cycles of successive enlargement and shrinkage of the separated zone are shown to be irregular in time, the maximum size of the recirculation bubble being submitted to discrepancies between successive cycles. This behaviour of the separation bubble is responsible for a low frequency temporal modulation of the amplitude of the separation and reattachment point motions and thus for the low frequency breathing of the separation bubble. These results tend to suggest that the SWBLI unsteadiness is related to this low frequency dynamics of the recirculation bubble; the oscillations of the reflected shocks foot being in phase with the motion of the separation point
Rutten, Mikal R. "Post treatment with the novel Deltorphin-E, a delta2 opioid receptor agonist, increases recovery and survival following severe hemorrhagic shock in behaving rats." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1313914351&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Повний текст джерелаChernukha, Yevheniia. "Investigation of phase transitions triggered by laser-induced focusing shock waves." Thesis, Le Mans, 2019. http://www.theses.fr/2019LEMA1038.
Повний текст джерелаThe ability of certain materials to change its ground state due to laser excitation has arisen a lot of opportunities for light-control of material properties. The field of photo-induced phase transitions counts a rich variety of chemical and physical processes triggered by light-matter interactions involved during the phase transition process. Recently it was reported that elastically driven cooperativity leads to the amplification of spin state in molecular crystals and prolonged the lifetime of the transient state with an ultra-short laser pulse. The cooperative response appears during the propagation of non-linear coherent strain waves, in other words shock waves, coupled with the order parameter field. Shock waves can be seen as a new challenging pathway to achieve a permanently switched state with appropriate excitations.First, we introduce time-resolved single-shot imaging combined with the laser shock focusing technique that makes it possible to generate, acoustically focus, and directly visualize under a microscope shock waves propagating and focusing along the sample surface. The spatial separation of the laser-influenced and strain-influenced regions makes it possible to disentangle the material changes produced solely by the shock waves. Second, we present experimental results involving the shock-focusing technique to materials undergoing phase transitions linked with a macroscopic change of their volume (spin-crossover systems, Mott insulators). Post-mortem analyses of the samples confirm permanent phase transition under specific experimental conditions. These innovative results open doors for a generic elastically driven cooperativity
Maheut, Yohann. "Etude expérimentale de la physique de l'allumage par choc dans le cadre de la fusion nucléaire par confinement inertiel." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0202/document.
Повний текст джерелаShock ignition is a novel approach for inertial confinement fusion where the compression and the ignition phases by a strong shock are separated. The scheme is promising to the extent that it can generate very high gains and can be tested on already existing lasers systems. In addition, this concept requires lower implosion velocities that allows for compressing more massive targets which limits the impact of hydrodynamic instabilities. However, the physic issues related to shock ignition are still largely unexplored especially experimentally. Indeed, even if the compression phase takes place in the well-known collisional regime (I<1014W=cm2), ignition requires a spike which intensity exceeds 1015W=cm2.This regime is strongly non-linear with the onset of parametric instabilities. These instabilities may decrease the absorption and can also generate suprathermal electrons that can preheat the central part of the fuel and make the compression less efficient. Another key issue is the capability of launching a strong shock in presence of a plasma corona which can deteriorate the laser-target coupling and produce lamentation. Nevertheless, theoretical considerations tend to show that if the energy of fast electrons is moderate (<100keV), they could improve the coupling, deposit their energy in the shock front and hence amplify it. The work presented in this thesis consists in testing these two issues : launching a strong shock in the conditions corresponding to shock ignition i.e. in presence of a plasma corona and study the effect of hot electrons on the shock strength by measuring their energy and their quantity
Herbomel, Gaëtan. "Analyse de la dynamique du facteur de transcription HSF1 "Heat Shock Factor 1" par microscopie de fluorescence." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00771403.
Повний текст джерелаRougier, Benoit. "Étude à coeur des propriétés de matériaux innovants par la compréhension de la propagation d'une onde électromagnétique à travers une onde de choc." Thesis, Toulouse, INPT, 2019. http://oatao.univ-toulouse.fr/24081/1/rougier.pdf.
Повний текст джерелаBaird, Nathan Alder. "Hypoxic gene regulation and high-throughput genetic mapping. /." Connect to title online (ProQuest), 2008. http://proquest.umi.com/pqdweb?did=1525703731&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Повний текст джерелаTypescript. Includes vita and abstract. Includes bibliographical references (leaves 45-52). Also available online in ProQuest, free to University of Oregon users.
Ulrich, Paul N. "Sensitivity of molluscs to temperature, osmotic shock, and infection by protozoa implications for temperate and polar bivalves /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 267 p, 2007. http://proquest.umi.com/pqdlink?did=1251900721&Fmt=7&clientId=79356&RQT=309&VName=PQD.
Повний текст джерелаChénais, Sébastien. "Nouveaux matériaux laser dopés à l'ytterbium : performances en pompage par diode et étude des effets thermiques." Paris 11, 2002. https://pastel.archives-ouvertes.fr/tel-00119661.
Повний текст джерелаThis thesis is a study of new ytterbium-doped crystals, made for the development of efficient (and sometimes broadly tunable) lasers emitting around 1 J. Ull. The first part presents the laser performance, under high power diode pumping, of new crystals: Yb:GGG, Yb:GdCOB, Yb:BOYS (and Yb:CaBOYS), Yb:SYS and Yb:YSO. The efficiency, tunability and thermal behaviour of these materials is discussed, and illustrated (when possible) by a comparison between materials of similar properties. Thennal effects limit the scaling toward higher powers in most of these materials: a comprehensive study of the se effects is performed in the second part of this thesis. We begin this part by setting the theoretical background necessary to understand thermal and thermomechanical effects in solid state lasers. After a description of the classical techniques employed to investigate thermal effects, we describe the experimental setup we used. It is based on a commercially available Shack-Hartmann wavefront sensor, and enables the measurement of the thermallens (including its aberrations) in end-pumped laser, under lasing and nonlasing conditions. We emphasize on the characteristics and limitations of this technique. Thermal lensing measurements are then reported, for the first time, in ytterbium-doped materials. Significant nonradiative effects have been demonstrated, whereas it is generally admitted that such effects are purely absent. We then explain how, thanks to a simple anâlytical model, it is possible to derive the quantum efficiency and the thermo- optical coefficient from these measurements. We also demonstrated the influence of the lasing wavelength on the thermalload, the reduction of thermal effects by the use of composite crystals, as weIl as the major role played by the photoelastic effect in the thermally-induced lens in Yb:GdCOB
Sartor, Fulvio. "Unsteadiness in transonic shock-wave/boundary layer interactions : experimental investigation and global stability analysis." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4705.
Повний текст джерелаA transonic interaction between a shock wave and a turbulent boundary layer is experimentally and theoretically investigated. The configuration is a channel flow over a bump, where a shock wave causes the separation of the boundary layer and a recirculating bubble is observed downstream of the shock foot.The mean flow is experimentally investigated by means of PIV, then different techniques allows to identify the main unsteadiness of this shock-wave/boundary-layer interaction. As recognised in similar configurations, the flow presents two distinguished characteristic frequencies, whose origins are still unknown.Numerical simulations are performed solving RANS equations. Results are in good agreement with the experimental mean flow, but the approach fails to predict the unsteady. The solution of RANS equations is then considered as a base flow, and a global stability analysis is performed. Eigenvalue decomposition of the Navier-Stokes operator indicates that the interaction is stable, and the dynamics cannot be described by unstable global modes.A linearised approach based on a singular-value decomposition of the Resolvent is then proposed: the noise-amplifier behaviour of the flow is highlighted by the linearised approach. Medium-frequency perturbations are shown to be the most amplified in the mixing layer, whilst the shock wave behaves as a low-pass filter.The same approach is then applied to a transonic flow over a profile, where the flow can present high-amplitude shock oscillations. The stability analysis can describe both the buffet phenomenon when an unstable mode is present, and the convective instabilities responsible of medium-frequency unsteadiness
Bardy, Simon. "Contrôle et optimisation du test d'adhérence par choc laser sur assemblages collés." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0061/document.
Повний текст джерелаBonding process generalization within aerospace, aeronautical and automotive structures faces the need of quantitative non-destructive evaluation of assemblies. Laser shock adhesion test (LASAT) meets this requirement by applying a calibrated stress to bonded joints and using non-destructive diagnostics to determine the post-shock state of the joint. The calibrated stress must disbond weak joints and keep correct assemblies intact. Optimal laser parameters determination aims at implementing this non-destructive proof test (ND-LASAT). It is achieved through application of a well-defined methodology, which implies the concerned assembly characterization by an experimental and numerical approach, followed by an optimization step. Optimization implies diversification of laser-matter configurations. Use of numerical tools for predicting loadings applied to bonded joints is then required. Models development within a multi-physics code is proposed and validated here to respond to this need. A significant effort has been made for evaluating models’ precision. Experimental demonstration of ND-LASAT process is achieved on three different bonded assemblies, and thus validating both methodology and numerical chain developed in this study
Chauvin, Alice. "Etude expérimentale de l'atténuation d'une onde de choc par un nuage de gouttes et validation numérique." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4732/document.
Повний текст джерелаThe interaction between a planar shock wave and an both homogeneous and monodispersed droplet water cloud is studied in a shock tube. The effects of the water volume fraction αd (1% %, 0.3 % et 0.1%), ratio between the volume of water and the volume of the cloud, the height of the two-phase medium Hd (70 cm, 40 cm et 15 cm), the droplets diameters φd (250 µm et 500 µm ) and the Mach number M (1.3 et 1.5) are studied for a volume fraction smaller than one per cent. During this interaction, the pressure is measured and the visualization of the cloud is obtained by direct shadowgraphy. A characteristic temporal evolution of the pressure induced by the propagation of the shock wave in such a mixture is highlighted. This behavior differs significatively from the one obtained with a solid particles cloud : the droplet atomization is responsible of this change. A zone where the pressure decreases directly after the pressure peak is observed at different stations located into the water cloud. The mitiagtion of the overpressure is shown: it can reach 80%of the pressure peak measured without cloud. In the numerical part, two fragmentation models are added, compared and validated in a comptutational, one dimensional, instationnary, Eulerien code in the case of dilute flows (αd<1 %). We show that the formulation of the production rate of droplets defined by the number of droplets growth, or the diameter droplet growth, must be used, respectively, with and without taking into account the deformation stage of the droplet breakup. Thus, the numerical results are in good agrement with those obtained experimentally
Courapied, Damien. "Etude de l’interaction laser matière en régime de confinement par eau avec deux impulsions laser. Application au test d’adhérence par choc laser." Thesis, Paris, ENSAM, 2016. http://www.theses.fr/2016ENAM0073/document.
Повний текст джерелаThe laser shock wave generation is a novel process becoming more and more common. The shock waves are used to generate mechanicals effects in the sample. The laser absorption results in the creation of a plasma at the surface. This plasma during its expansion creates a shock wave propagating through the sample. This work aims to study the various phenomena involved in the laser-matter interaction. In the field of laser generated shock waves, two different processes exist: the Laser Shock Peening (LSP) and the LASer Adhesion Technique (LASAT). The new challenge deals with the limitations of those processes and the solutions to be setting up to improve them. Some ideas concerning the confinement improvement as water substitution or thermal coatings optimization are suggested in this work. Moreover, the use of double delayed laser pulses allows, for LASAT, the location of main tensile stresses near interfaces. However, for LSP, some aspects dealing with the profitability linked to the peening rate are investigated here. Last but not least, whether the very short (0 to 1000 ns) or very long delays (from 200µs to 200ms), the study of the laser-matter interaction phenomena allows to overcome some limitations for both laser shock processes
Phillips, Michelle René. "Functional genetic analysis of two non-model marine invertebrates : physiologically and environmentally induced changes in gene expression /." view abstract or download file of text, 2007. http://proquest.umi.com/pqdweb?did=1400950801&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Повний текст джерелаTypescript. Includes vita and abstract. Includes bibliographical references (leaves 179-196). Also available for download via the World Wide Web; free to University of Oregon users.
Ghrib, Meriem. "Contrôle santé des structures composites : génération de délaminages par choc laser et quantification par apprentissage machine." Thesis, Paris, ENSAM, 2017. http://www.theses.fr/2017ENAM0070/document.
Повний текст джерелаIn this work, we approach delamination quantification in Carbon Fiber Reinforced Polymer (CFRP) laminates as a classification problem whereby each class corresponds to a certain damage extent. A Support Vector Machine (SVM) is used to perform multi-class classification task. Classically, Signal Based Features (SBF) are used to train SVMs when approaching SHM from a machine learning perspective. In this work, starting from the assumption that damage causes a structure to exhibit nonlinear response, we investigate whether the use of Nonlinear Model Based Features (NMBF) increases classification performance. NMBF are computed based on parallel Hammerstein models which are identified with an Exponential Sine Sweep (ESS) signal. Dimensionality reduction of features vector using Principal Component Analysis (PCA) is also conducted in order to find out if it allows robustifying the quantification process suggested in this work. The proposed quantification approach was first tested and validated using simulation results. Thereafter, experimental results on CFRP composite plates equipped with piezoelectric elements and containing various delamination severities are considered for demonstration. Delamination-type damage is introduced into samples in a calibrated and realistic way using LASER Shock Wave Technique (LSWT) and more particularly symmetrical LASER shock configuration. We have experimentally demonstrated that such a configuration of LASER shock is an effective alternative to conventional damage generation techniques such as conventional impacts and Teflon inserts since it allows for a better calibration of damage in type, depth and size
Ruocco, Alessandro. "Modelling of ponderomotive laser self-focusing in a plasma with a hydrodynamic code in the context of direct-drive inertial confinement fusion." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0043.
Повний текст джерелаPonderomotive laser self-focusing poses a threat to the success of the inertial confinement fusion (ICF) program: it locally enhances the laser intensity, which causes two detrimental effects: i) undermining the uniformity of the shock wave launched into the target, and ii) increasing the onset of laser-plasma instabilities. Despite several optical techniques have been implemented to smooth ponderomotive effects, they still remain a concern in case of crossing beams or in spike pulse-plasma interaction as in shock ignition.In order to ameliorate the interpretation capability of radiation-hydrodynamics simulations, the Paraxial Complex Geometrical Optics (PCGO) module has been implemented in the hydrodynamics code CHIC in two-dimensional planar geometry, and is an improved version of the standard Ray-Tracing technique. PCGO accounts for nonlinear laser-plasma interaction such as ponderomotive force and hot electrons generation and propagation, usually neglected in hydrodynamic simulations. This approach is also used for creating spatially modulated laser beams by superposing Gaussian PCGO beamlets in the far-field. Their intensity envelope generates the intensity fluctuations. Although this PCGO-based method has improved the accuracy of CHIC simulations, the superposition of PCGO beamlets produces larger and longer speckles than real ones, and their self-focusing may be overestimated.In this thesis, we develop a method for describing and controlling the excessive ponderomotive self-focusing developing in PCGO speckles while performing CHIC simulations. This study has been conducted in stationary plasmas. First, we investigate self-focusing of a single Gaussian PCGO beamlet in a homogeneous nonabsorbing plasma by comparing its behavior to a Gaussian-shaped beam modeled with the paraxial electromagnetic code HARMONY. This comparison allows to define the domain of beam power where the PCGO approximation is valid. We found that within 4 times the critical power, PCGO correctly reproduces HARMONY results.Afterwards, we consider the self-focusing of a PCGO speckle created by superposition of several beamlets, referred to as a multi-beamlet speckle. This speckle stands for a reference for any PCGO speckle created in CHIC. The reduction of the speckle intensity enhancement is quantified as a function of the number of superposed beamlets and by considering two strategies for multi-beamlet speckle shaping: random and regular.The latter configuration demonstrates better performances in controlling and reducing ponderomotive effects for a number of beamlets equal to three: our results show that the critical power of a three-beamlet speckle is twice higher compared to the critical power of a Gaussian beam with same characteristics.This novel speckle configuration has been implemented in CHIC and employed to generate multi-speckle beams whose speckle intensity distribution obeys to an exponential law. We then studied the self-focusing of a spatially modulated beam (multi-speckle beam) in a homogeneous nonabsorbing plasma and show that our configuration allows to properly treat ponderomotive effects for different laser intensities: this method describes the speckle intensity statistics modification induced by speckle self-focusing and inter-speckle interaction as observed in electromagnetic simulations.The last part of the thesis is devoted to establish a baseline towards modelling of laser self-focusing in real ICF conditions. For this purpose, our results are extended to absorbing plasmas with a linear density profile. Speckle self-focusing is investigated here for different plasma lengths, and the effect of laser absorption is discussed. It is demonstrated that the proposed method of creation of a multi-beamlet speckle pattern operates in the conditions relevant to the direct-drive ICF. It allows to control efficiently the speckle self-focusing and its effect on the speckle intensity distribution in plasma
FOURNIER, JEAN. "Generation d'ondes de choc par laser pulse de forte energie : applications mecaniques et metallurgiques." Palaiseau, École polytechnique, 1989. http://www.theses.fr/1989EPXX0007.
Повний текст джерелаVanhuyse, Fabrice. "Évaluation des bénéfices thérapeutiques apportés par l’hypothermie dans le traitement du choc cardiogénique sous ECMO chez l’animal." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0320/document.
Повний текст джерелаCardiogenic shock is still considered as a severe medical condition. Despite much progress in the treatment of the cardiogenic shock, this disease is still associated with a high mortality. An important advance in the treatment of the cardiogenic shock is the use of ECMO. However, despite the restoration of a proper circulatory flow, we are still facing significant mortality in these patients. The first part of this manuscript is a reminder of the main concepts of the cardiogenic shock and ECMO and the concept of hypothermia. In the second part, we report the results of our experimental research who highlighted a beneficial effect of hypothermia in cardiac function and vascular reactivity in animals in cardiogenic shock treated by ECMO. In the third part we discuss our results and we try to rapport physiological explications of our results
Abou-Zaid, Ahmed S. "The transmission of U.S. financial and monetary shocks to emerging MENA stock markets /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1564026641&sid=11&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Повний текст джерела"Department of Economics." Keywords: Monetary shocks, MENA, Middle East and North Africa, Emerging markets, Shocks, Monetary announcements, Pass through Includes bibliographical references (p. 77-83). Also available online.
Lafon, Marion. "Étude du schéma d'allumage par choc en fusion par confinement inertiel." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14403/document.
Повний текст джерелаThe Shock Ignition (SI) scheme is an alternative to classical ignition schemes in Inertial Confinement Fusion. Its singularity relies on the relaxation of constraints during the compression phase and fulfilment of ignition conditions by launching a short and intense laser pulse (~500 ps, ~300 TW) on the preassembled fuel at the end of the implosion.In this thesis, it has been established that the SI process leads to a non-isobaric fuel configuration at the ignition time thus modifying the ignition criteria of Deuterium-Tritium (DT) against the conventional schemes. A gain model has been developed and gain curves have been infered and numerically validated. This hydrodynamical modeling has demonstrated that the SI process allows higher gain and lower ignition energy threshold than conventional ignition due to the high hot spot pressure at ignition time resulting from the ignitor shock propagation.The radiative hydrodynamic CHIC code developed at the CELIA laboratory has been used to determine parametric dependences describing the optimal conditions for target design leading to ignition. These numerical studies have enlightened the potential of SI with regards to saving up laser energy, obtain high gains but also to safety margins and ignition robustness.Finally, the results of the first SI experiments performed in spherical geometry on the OMEGA laser facility (NY, USA) are presented. An interpretation of the experimental data is proposed from mono and bidimensional hydrodynamic simulations. Then, different trails are explored to account for the differences observed between experimental and numerical data and alternative solutions to improve performances are suggested
Gashegu, Kagabo J. "Contribution à l'étude des caspases au cours de l'apoptose physiologique et induite par l'acide rétinoïque et l'irradiation lors du développement crânio-facial précoce: corrélation avec la protéine HSP110." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209228.
Повний текст джерелаBiamino, Laurent. "Etude expérimentale de l'interaction d'une onde de choc avec une structure mobile autour d'un axe." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10093/document.
Повний текст джерелаThis thesis is based on an experimental study carried out in shock tube; in particular, this is an experimental approach to the study of fluid-structure interaction. Consider a rigid body which is allowed to rotate only around an axis and which closes a confined space. If a shock wave crosses the content of the confined space, the body will accelerate and rotate around its axis. Specifically, the shock wave will increase the physical characteristics, especially its pressure, of the fluid acting on the impacted face of the door. The opposite side of the door is not influenced by the incident shock wave, only one of its faces is subjected to overpressure. Following the first impact, the resulting imbalance imposes a mechanical action on the door that will increase its speed and make it turn around its rotation axis. The difficulty comes when the door begins to open: the volume boundaries in which the fluid is contained are modified. Leaks occur and the gas kept in this closed volume can now flow to the atmosphere. Communication between the gas acting on each side of the door is created modifying their properties and consequently the pressure acting on each side of the door.The mechanical actions that apply to the door are no more the same with time, and therefore the acceleration of the door is changing. As the door moves, the fluid problem continues to be changed and in turn it changes its action on the door. This interaction process continues until either the limits of the problem ceases to be changed, the door cannot move, or when the mechanical actions acting on the door are in equilibrium, fluids on each side of the door are in the same physical state. The presented work is a study of the parameters of the fluid or the solid motion which are main actors in the behavioral law managing this complex system. In this aim, we designed an experimental device involving the physics that we have described and we have adapted it to a shock tube. Testing many experimental configurations, we could determine how the internal flow of a shock tube evolves when the end of this shock tube is more or less open.How a closed door reacts to the impact of a shock wave and what are the implications for the evolution of the involved fluids? What are the consequences of a different position of the door at the instant of the impact with the incident shock wave? What role plays the intensity of the incident shock wave or the inertia of the door on this dynamic?
Singh, Raj Laxmi. "Strong radiative shocks relevant for stellar environments : experimental study and numerical approach." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066092/document.
Повний текст джерелаStrong shocks are present in various astrophysical phenomena. Such shocks are strongly influenced by the radiation through its coupling with hydrodynamics. Thus their topology and dynamics are quite complex. Generating such hypersonic shocks in the laboratory, with controlled conditions, is thus an adequate tool to study the influence of radiation and to compare them with numerical simulations. Such shocks can be generated by intense lasers and electromagnetic devices.The first part of this dissertation concerns the numerical and experimental study of the interaction of two counter propagating laser-driven shocks. The experiments, performed at the kJ PALS laser facility allowed to generate shocks with different speeds ($\sim$ 30-55 km/s and 10-25 km/s), in noble gases and low pressure (less than 1 bar). Several diagnostics were implemented: visible interferometry, time- and space-resolved visible spectroscopy, and time integrated XUV spectroscopy. Our experiment shows a strong interaction of one radiative precursor onto the second one. The physical parameters of the plasma were deduced from the diagnostics and compared with 1-D simulation results. The second part is devoted to the design of an experiment where the shock is generated electromagnetically. The optimization of this generator is presented and also the full experimental set up which allows studying shock $\sim$ 30 km/s in noble gas at $\sim$ 1 mbar
Cattabiani, Alessandro. "Simulation of low- and mid-frequency response of shocks with a frequency approach." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN012/document.
Повний текст джерелаRecently, aerospace and automotive industries are increasingly interested in virtual testing since it speeds-up the design process and reduces costs. This is particularly true in case of space industries where specimens are very costly because rockets are unique or produced in limited number. Ariane 5 (and 6 in the future) is a heavy lift launch rocket manufactured by CNES and Airbus DS. During launch the protective fairing is severed from the rocket by pyrotechnic charges once sufficient altitude is reached (typically above 100 km). Shock vibrations propagate throughout rocket shell structure to the payload which can be damaged. The HSS3+ ground full-scale test was developed by CNES and Airbus DS to investigate such eventuality. This thesis develops a software capable of simulating the HSS3+ test to characterize explosion loads and to reduce the number of future required real tests. The task is difficult since the interesting frequency band is wide (up to mid-frequency), the explosion loads are unknown, the geometry is complex, and the specimen is composed of sandwich composite shells. The software called Transient Analysis for PYROtechnic Shocks in Shells (TAPYROSS) is based on the Variational Theory of Complex Rays (VTCR) which is a Trefftz method specifically developed to analyze the mid-frequency band. Many theory and performance improvements are introduced to address this real industrial test case. At the end, comparisons between real data and simulations validate TAPYROSS and characterize explosion loads
Tabka, Maher. "Les effets des substances vasoactives sur les perturbations hémodynamiques, systémiques et splanchniques induites par les états de choc et la cirrhose." Thesis, Angers, 2015. http://www.theses.fr/2015ANGE0064/document.
Повний текст джерелаThe impairment of vascular regulatory mechanisms observed in cirrhosis and shock situations, reduces the effectiveness of vasoactive substances used in treatments. The aim of this study is the hemodynamic, systemic and splanchnic assessments of vasoactive molecules proposed for the treatment of septic shock, hemorrhagic shock and cirrhosis complications (hydrogen sulfide [H2S], terlipressin [TP] and norepinephrine [NE]). In a model of ischemia/reperfusion (I/R), sepsis has no particular impact on the kidney since renal blood flow varies in response to mean arterial blood pressure variations, including an auto-regulation phenomenon. Sepsis is very rapidly associated with hypervelocity of blood flow in peritubular capillaries and renal dysfunction, both of wich are reserved by NE infusion. In hemorrhagic shock model controlled and resuscitated by Gelofusin® perfusion, we demonstrated that inhibition of endogenous H2S worsening renal dysfunction due to decreased renal peritubular microcirculatory velocities and promotes capillary leak syndrome. While the exogenous administration of H2S, could cause a negative feedback on the activity of the principal enzyme of endogenous H2S production, the CSE. During portal hypertension by cirrhosis in rats, NE increases the portal venous pressure, at low doses, and is more efficient than vasopressin on the portal veins of cirrhotic rats in vitro. However TP significantly reduces the mesenteric artery blood flow and the portal vein pressure. Taken together, TP could reduce the variceal bleeding risk associated with cirrhosis in comparison to NE
Gossez, Morgane. "Rôle des cellules B régulatrices dans l’immunodépression induite par le choc septique." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1017/document.
Повний текст джерелаSepsis in a major health problem associated with rising incidence and high mortality rate. In septic patients, an initial proinflammatory response causing life-threatening organ failures is followed by the development of a deep immunosuppression, associated with increased risk of secondary infections and death. In this context, immunostimulating therapies are currently tested. However, success of this strategy requires identification of relevant therapeutical targets and biomarkers allowing individualisation of treatments. B lymphocytes have been poorly studied in sepsis. Moreover, existence of regulatory B cells was recently revealed in several clinical contexts. Thus, we made the assumption that regulatory B lymphocytes or plasma cells could be implied in sepsis-induced immunosuppression establishment.In septic shock patients, we showed that B cells present with decreased proliferation capacity and exhausted-like profile, and are able to produce immunosuppressive IL-10 (Journal of Immunology 2018). We also observed blood plasmacytosis in patients, confirmed by mass cytometry analysis (Scientific Reports 2018). In a murine model of sepsis, the ability of plasma cells to inhibit T cell proliferation ex vivo, and their phenotypic profile suggest for the first time the existence of regulatory plasma cells in sepsis.The role of regulatory plasma cells within sepsis-induced immunosuppression has to be further explored in patients (underlying regulatory mechanisms, associations with clinical outcomes and viral reactivations…). It could highlight novel biomarkers for patients’ monitoring and innovative therapeutical approaches
Bréda, Carole. "Confinement à l'aide de mousse aqueuse des effets combinés de souffle et de projection de fragments générés par la détonation d'un engin explosif." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0047/document.
Повний текст джерелаThe fight against Improvised Explosive Device (IED) effects represents a permanent challenge for homeland security and armed forces protection deployed abroad. Aqueous foam was identified as a protective technology against blast effects in the 1970s. Several physical characteristics can account for this attenuation but their relative influences are still not completely determined and require further investigation. The objective of this study is to improve the knowledge of the physical phenomena governing the interaction between an aqueous foam layer and a shock/metallic fragments combination. Depending on the distance between the explosive charge and the absorption medium, the shock is likely to arrive before the fragments consequently modifying the foam structure. Experiments with a single fragment were undertaken in a one dimensional configuration. Obtained results were applied to predict the foam mitigation capability against a complete explosive charge detonated in free field at the French-German Research Institute of Saint-Louis (ISL) in the research group "Protection against Explosives". Pressure measurements in shock tube with visualization of shock/bubbles interaction provided precise information on the foam structure evolution during the impact process. These last experiments were conducted in LBMS (ENSTA Bretagne) and in the research group "Aerodynamic, Measurements and Simulations" (ISL), using a shock tube generating blast wave profiles
Voisin, Marina. "Tenue aux chocs d'une adhérence moléculaire renforcée : application à des systèmes optiques spatiaux embarqués." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0585/document.
Повний текст джерелаThe fused silica glass direct bonding consists in joining two surfaces without using any adhesive. This technology is used in particular to manufacture optical systems like optical slicers or interferometers used in terrestrial optics. The final aim in the development of this technology is to integrate these assemblies in spatial optics systems. However the spatial environment is totally different from the terrestrial one. A satellite may undergo shocks, vibrations or thermal fatigue. It is necessary to characterize with accuracy the direct bonded interface under these solicitations to respect the European Space Agency requirements. The aim in this works consists to characterize the direct bonding shock resistance. In this context, a new test machine has been developed to lead on an experimental campaign. This new machine design consists to generate a shock in a specimen placed in modified Arcan device. The first tests are performed on adhesively-bonded assemblies in aluminium with three different adhesives to validate the bench behaviour. After, an experimental campaign is performed on silica glass direct bonding samples with different bonded procedure. The shock fracture energy is defined for each type of interface with dynamic tests. Following static tests, a simulation by finite elements is used to define the critical stress with a stress criterion. To finish, a shock study on a representative structure, in our case a Corner cube optic, is performed
Mongardon, Nicolas. "Étude expérimentale de l'hypothermie ultra-rapide par ventilation liquide totale au cours de situations critiques d'ischémie-reperfusion." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC0088.
Повний текст джерелаUltra-fast cooling with total liquid ventilation and ischemia-induced multi-organ failureIschemia and reperfusion injury is a major challenge in anesthesiology and critical care. Resolution of the underlying condition and organ replacement therapies are the cornerstone of the treatment. Hypothermia exhibits a myriad of protective effects, but delays of application may blunt its benefits. Ultra-fast cooling with total liquid ventilation (TLV) is an emerging strategy, which consists in lung ventilation with cold perflurocarbons and uses the lungs as a heat exchanger while maintaining normal gas exchanges. Our objective was to investigate the effects of TLV-induced cooling during multiorgan failure caused by systemic ischemia-reperfusion in rabbits.In a first study, the application of 30 minutes of supraceliac aortic cross-clamping followed by 300 minutes of reperfusion led to severe multiorgan failure in control animals. On the contrary, animals submitted to hypothermic TLV reached the temperature of 33°C within less than 15 minutes. Hypothermia was maintained during 75 minutes before rewarming. This brief period of hypothermic TLV attenuated biochemical and histological markers of multiorgan failure. Cardiovascular and liver dysfunctions were limited by this short period of hypothermic TLV, even when started after reperfusion. Conversely, acute kidney injury was limited only when hypothermia was started before reperfusion.In a second study, non-shockable cardiac arrest from respiratory cause was responsible for a high rate of mortality and a severe post-cardiac arrest syndrome. Hypothermic TLV had potent neuro- and cardio-protective effects, as well as reduced inflammatory syndrome. Early preservation of the blood-brain barrier integrity and cerebral hemodynamics as well as reduction in the immediate reactive oxygen species production in the brain, heart, and kidneys were also notable.These studies demonstrate that ultra-fast cooling by TLV alleviates the deleterious effects of ischemia-reperfusion. The optimal duration and timing of TLV-induced hypothermia for end-organ protection in hypoperfusion states remains to be determined
Jaouen, Vincent. "Traitement des images multicomposantes par EDP : application à l'imagerie TEP dynamique." Thesis, Tours, 2016. http://www.theses.fr/2016TOUR3303/document.
Повний текст джерелаThis thesis presents several methodological contributions to the processing of vector-valued images, with dynamic positron emission tomography imaging (dPET) as its target application. dPET imaging is a functional imaging modality that produces highly degraded images composed of subsequent temporal acquisitions. Vector-valued images often present some level of redundancy or complementarity of information along the channels, allowing the enhancement of processing results. Our first contribution exploits such properties for performing robust segmentation of target volumes with deformable models.We propose a new external force field to guide deformable models toward the vector edges of regions of interest. Our second contribution deals with the restoration of such images to further facilitate their analysis. We propose a new partial differential equation-based approach that enhances the signal to noise ratio of degraded images while sharpening their edges. Applied to dPET imaging, we show to what extent our methodological contributions can help to solve an open problem in neuroscience : noninvasive quantification of neuroinflammation
Knutsen, Karen Patrick. "Reciprocal Haunting : Pat Barker's Regeneration Trilogy." Doctoral thesis, Karlstad : Faculty of Arts and Education, English, Karlstads universitet, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1646.
Повний текст джерелаGlavier, Ludovic. "Conception et développement d'un micro détonateur électrique intégrant des nanothermites pour l'amorçage par impact d'explosifs secondaires." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30016/document.
Повний текст джерелаPyrotechnic systems are the keys for satellite launching on orbit. Those systems are used for engines ignition, stage separation and self-destruction. To activate those functions, different kinds of initiators are used to generate a flame, pressure from gas expansion and a shock wave. This work involved following a previous thesis on the design of a smart and safe initiator able to generate a flame and pressure form gas expansion but not a shock wave which is essential in achieving certain functions on launcher as stage separation or neutralization. The initiator is controlled by digital controls, it contain local energy source, a mechanical safety barrier and a PyroMEMS for electro-pyrotechnical conversion. This initiator is design to replace Ariane 5 current pyrotechnic systems because they are heavy, bulky, they contain a large amount of pyrotechnic substance increasing the cost of manufacturing and storage. Also detonators and transmission lines contain lead banned by the European REACh. The goal of these thesis works is to design the detonator function from the flame generated by the PyroMEMS containing 50 µg of Al / CuO nanothermite in a volume less than 0,83 cm3 without primary explosive. After the study of secondary explosive priming methods and the state of art of existing detonators, we designed an architecture running on propelling a projectile creating a shock wave through impact. The development of this detonation function was used to study the behavior of different nanothermites (Al / CuO, Al / Bi2O3, Al / MoO3 and Al / PTFE) with a view to propel the projectile. An interior ballistic model is developed with the combustion nanothermite Al / Bi2O3 doped with PTFE to conclude that it is not possible to use nanothermites to ignite in detonation by impact, by a shock to Detonation Transition) a secondary explosive such as RDX. A propulsion system based on the combustion of RDX initiated by nanothermite is then developed with a study of the influence of dimensional parameters. Achieving a final demonstrator allows to ignite in detonation RDX demonstrates the feasibility of such a device and to validate design choices
Hinzpeter, Alexandre. "Régulation du canal chlorure CIC-2 par la chaperone Hsp90 et l'environnement lipidique : lien avec le stress cellulaire." Paris 6, 2006. http://www.theses.fr/2006PA066045.
Повний текст джерелаPerego, Jessica. "Modulation pharmacologique des voies de signalisation des TLRs par le Guanabenz, un inhibiteur de la réponse au stress." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4066.
Повний текст джерелаSustained immune reaction is strictly interconnected to pathogenic situations. For this reason, the activation of immune cells is controlled by multiple pathways. A cross-talk between microbial sensing and Endoplasmic Reticulum (ER) homeostasis has been discovered. Abnormal accumulation of proteins in the ER is a sign of cellular malfunction and triggers emergency rescue pathways, collectively known as the Unfolded Protein Response (UPR). UPR induction triggers or amplifies inflammatory signals by dendritic cells (DCs). GADD34/PP1 is a holophosphatase complex that dephosphorylates eIF2α and participates in the UPR feedback loop, by restoring protein translation. It has been shown that GADD34 plays an important role in controlling the expression of pro-inflammatory cytokines, especially type I interferon. In dendritic cells (DCs), pathogens are sensed by Pathogen Recognition Receptors (PRRs); the better characterised class of PRRs being the Toll-Like Receptors (TLRs). Thus, the aim of my thesis is to investigate how TLRs and ER-signalling pathways intersect and how this can be used to control pathogenic states, with particular attention for the GADD34/PP1 complex. Using both human and mouse DCs, we show that guanabenz (GBZ), an inhibitor of the GADD34/PP1 complex, blocks endosomal TLRs activation. The same inhibitor rescues mice viability in a TLR-dependent septic shock model and controls the circulating autoantibodies in a lupus model. Our studies show that TLR9 is particularly sensitive to GBZ. We show also that GBZ has a previously unidentified effect on CH25H, an enzyme that hydroxylates the cholesterol in 25-hydroxycholesterol, recently linked to TLRs signaling
Marty, Ludovic. "Etude numérique et expérimentale d'une onde de choc induite par impact laser dans une cible solide." Poitiers, 1988. http://www.theses.fr/1988POIT2273.
Повний текст джерелаSakaki, Takaya. "Etude expérimentale du transport d'électrons rapides et des ondes de choc générées par laser dans le cadre de la fusion inertielle." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0107/document.
Повний текст джерелаThis manuscript presents three experiments conducted as part of a nuclear fusion byinertial confinement. The first experiment is the study of the fast electron beam propagationin a pre-compressed plasma in the fast ignition scheme. Two other experiments about theshock wave generation in plasmas were conducted in the ignition shock pattern.The first experiment was devoted to the study of the fast electron beam transport in a compressed target. The implosion of the target with a cylindrical geometry was carriedout with the GEKKO XII laser facility (ILE Osaka, Japan). The fast electron beam wasgenerated by the LFEX laser ( 1019W/cm2) and its propagation through the compressedcylinder was observed with several X-ray diagnostics. This experiment showed the guidingeffect of the electron beam resulting from self-generated magnetic fields. Furthermore, theresults of this experiment were in good agreement with numerical simulations. This studywas the subject of the publication Approach to the study of fast electron transport incylindrically imploded targets, Laser and Particle Beams, 33,525-534,(2015). Two other experiments were performed to study the propagation of strong shockscreated by lasers in a plasma. These were carried out with different laser systems. In the firstexperiment with the Gekko XII laser, we observed the creation and the propagation of twosuccessive shock waves in an ablation plasma in CH and Be. The objective to characterizethe amplification of a transmitted shock by the collision of two counter propagatingshocks has been partially realized. The comparison of the experimental results with thehydrodynamic simulations enabled us to confirm an amplification of the shock by a factor2 in pressure in the condition of this experiment. The shot with a Be target allowed todevelop and to validate the diagnostic method of X-ray radiography for shock propagation.The second experiment was performed with laser PHELIX GSI (Darmstadt, Germany).The purpose of this experiment was to study the generation of strong shocks. They wereapplied to study the equation of state of carbone in WDM state for the planetology. Thecondition of pressure and density for the carbon were obtained by deducting the pressureand the velocity of the shock wave chronometric diagnostics employed in this experiment.In this experiment, diamond was at the metallic liquid phase with the pressure of 7 Mbarand the temperature of 15,000 degrees
Suas-David, Nicolas. "Jets hypersoniques sondés par temps de déclin d’une cavité optique : application à l’astrophysique de laboratoire." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S009/document.
Повний текст джерелаA huge quantity of infrared spectra is collected by terrestrial and space telescopes from cool astrophysical objects (500-3000 K) like exoplanet (hot Jupiter) and brown dwarf atmospheres or circumstellar envelop of AGB stars. The main purpose of this thesis connected to experimental astrophysics is to provide high temperature data of key molecules by reproducing in the laboratory some aspects of such environments. A new setup built in Rennes couples a High Enthalpy Source to a highly sensitive Cavity Ring-Down Spectrometer. The gas studied, heated in the reservoir up to 2000 K, is expanded in a vacuum chamber through a circular nozzle and the resulting hypersonic jet can be probed at any location. Computational flow dynamics (CFD) calculations associated to a modeling of the infrared absorption lead to synthetic lines which are in very good agreement with the observed spectra. These numerical data were used to attribute the unusual double peak line shapes to the particular flow structure of axisymmetric hypersonic jets. Strong out-of-equilibrium conditions were evidenced in the isentropic core of the expansion. High vibrational temperature (1350 K) and rotational temperature lower than 10 K were recorded inside a jet of CO seeded in Ar. This degrees-of-freedom decoupling greatly simplifies the rotational structure of the recorded infrared spectra and unveils the presence of hot bands stemming from highly excited vibrational states which are significantly populated at high temperature. Our approach is therefore well suited for the study of rotationally cold hot bands of polyatomic molecules which are virtually missing in spectroscopic databases. A complementary approach consists in probing the shock layer formed upstream of an obstacle set perpendicularly to the hypersonic flow axis. Rotational temperature raises abruptly downstream the shock, revealing transitions associated with high J quantum numbers. These two methods were successfully applied to methane which plays an important role in numerous astrophysical environments. In addition to the acquisition of infrared spectroscopic data, the relaxation of internal degrees-of-freedom of CO seeded in different carrier gases (Ar and He) was studied by following the evolution of rotational and vibrational temperatures along the flow, in the isentropic core as well as in the peripheral viscous layers. These temperatures were compared to excitation temperatures calculated by an ab initio method in order to validate collision rates. These data will feed databases needed for the development of radiative transfer codes with a view to a better modeling of spectra observed from "hot" astrophysical environments
Martin, Justin. "Etude et caractérisation d'onde de pression générée par une décharge électrique dans l'eau. Application à la fracturation électrique de roches." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3024/document.
Повний текст джерелаNumerous parts of the world contain huge unconventional gas reserves which are located in low permeability rocks, and consequently, cannot be produced by classical drilling techniques. Besides its numerous detractors, the only currently available method to exploit these reservoirs relies on hydraulic fracturing. For these reasons, a research collaboration was started in 2007 between the Total Company and the Electrical Engineering Laboratory of Pau university (recently renamed SIAME Laboratory). The main goal was to study the potential concerning the use of the electrical fracturing technique as an alternative to hydraulic fracturing. This method is based on a dynamic rock fracturing process through the applying of a pressure wave enhanced by the generation of an electrical arc into a liquid. This work, which is financed by TOTAL through a CIFRE funding, follows the track initiated on this topic and mainly intends to improve the knowledge concerning the critical part of the fracturing process: the electrical discharge in water and the resulting pressure wave characterization. In this purpose, the importance of the circuit and of the arc electrical parameters was demonstrated in terms of current injection and power transfer. An empirical formula used to predict the dynamic pressure value has consequently been established. In order to optimize the electro acoustic efficiency, a specific study was performed on the liquid dielectric breakdown modus. This work allowed us to suggest new solutions concerning the dynamic pressure wave control. Finally, the fluid thermodynamic properties effects on its dielectric strength, on the energy consumption, and on the pressure wave propagation were analyzed in order to draw conclusions for the process optimization
Herraiz, Michael. "Graphène et fluorographène par exfoliation de graphite fluoré : applications électrochimiques et propriétés de surface." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC094/document.
Повний текст джерелаIts electronic conductivity or its optical transparency are unequaled physicochemicalproperties of graphene which explain the increased number of exfoliation methods based ongraphitic precursors to obtain this material. To overcome the use of a graphite/graphene oxidecharacterized by a poorly controlled surface chemistry, graphite fluorides, with variablecrystallinity and also fluorine concentration, were prepared by fluorination of graphite under puremolecular fluorine atmosphere after optimization of the process parameters. The obtainedprecursors, whether by dynamic or static fluorination, were characterized : X-Ray diffraction, FTIRand Raman spectroscopies for the structure, and their texture probed by Scanning andTransmission Electron Microscopy. After that, three methods of exfoliation were developed, basedon different mechanisms: i) a thermal shock, already known but decomposition mechanisms wererefined in this study, ii) an exfoliation within liquid medium by pulsed electrochemical treatment,using for the first time a fluorinated graphite for the synthesis of few-layered fluorinated grapheneand finally iii) an unconventional method, based on the interaction between femtosecond laser andhighly fluorinated graphite to induce mechanisms like controlled reduction, and especially for thisstudy exfoliation of the matrix. These methods have permit to highlight the interest of fluorine inthe current race for the synthesis of graphene, and have shown the production of graphenematerials, having an interesting fluorinated residual functionalization for some applications
Demol, Thierry. "Etude de transducteurs en barrette adaptés au contrôle santé par ondes de Lamb de structures aéronautiques composites : application a la caractérisation de l'impact basse vitesse." Valenciennes, 1998. https://ged.uphf.fr/nuxeo/site/esupversions/97d8f63c-45e8-4817-9d51-8352caa3e003.
Повний текст джерелаNowadays, aerospace industries widely use composite materials because of their attractive characteristics. Therefore, suitable nondestructive evaluation methods have been developed. Among them, the use of Lamb waves allows the inspection of large plates with a small number of transducers, making it possible to consider eventually the design of smart materials and structures. Within these developments, the objective of this work is to design and evaluate thin transducers, consisting in several independent piezoelectric elements, called “array transducers”. In the first part, we study the propagation of Lamb waves in stratified carbon-epoxy composites, and the different methods available to inspect these materials are presented. In the second part, we design two couples of moveable transducers. The generated waves are identified using different methods and the efficiency of those transducers is compared with that of classical angled transducers. The principle on which the transducers work is verified experimentally, then improvements are proposed. In the third part, the surface of composites of different lay-ups is equipped with array transducers in order to evaluate their efficiency. The final part is devoted to an assessment of the passive behavior of the transducers when a plate is submitted to the low velocity impacts to which the composites under study are highly sensitive. The experimental results show beyond doubt that the impacts responsible for internal damage can be detected through simple signal processing. As is finally shown, all these results open up new prospects as regards the possible uses to which these array transducers can be put