Дисертації з теми "Noyau de la terre"
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Roudil, Pascal. "Etude sismologique de la structure du noyau terrestre au voisinage de la frontière noyau externe-noyau interne." Toulouse 3, 1996. http://www.theses.fr/1996TOU30170.
Повний текст джерелаSiebert, Julien Philippe. "Ségrégation expérimentale du noyau de la Terre en conditions réductrices." Paris 7, 2004. http://www.theses.fr/2004PA077165.
Повний текст джерелаBrito, Daniel. "Approches expérimentales et théoriques de la dynamique du noyau terrestre : tourbillon géostrophique de gallium liquide dans un champ magnétique, anisotropie et rotation de la graine, chemins d'inversion." Paris 7, 1998. http://www.theses.fr/1998PA077022.
Повний текст джерелаBelaidi, Ramdane. "Contribution à l'étude du mécanisme d'intéraction K⁺-noyau : possibilités offertes par le meson K⁺ comme sonde de la structure du noyau." Bordeaux 1, 1987. http://www.theses.fr/1987BOR10555.
Повний текст джерелаHulné, Serge. "Investigation des deformations octupolaires dans le noyau **(217)fr par spectroscopie yrast." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13220.
Повний текст джерелаCardin, Philippe. "Aspects de la convection dans la Terre : couplage des manteaux inférieur et supérieur, convection thermique du noyau liquide." Paris 6, 1992. http://www.theses.fr/1992PA066073.
Повний текст джерелаAubert, Julien. "Modèles expérimentaux et numériques de la convection dans le noyau de la Terre." Phd thesis, Université Joseph Fourier (Grenoble), 2001. http://tel.archives-ouvertes.fr/tel-00683861.
Повний текст джерелаLégaut, Gédéon. "Ondes de torsion dans le noyau terrestre." Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10158.
Повний текст джерелаEarth magnetic field is due to external and internal sources. On decennal time scale, this field has abrupt variations called "geomagnetic jerks". A possible explanation concerns Alfvèn magnetic waves in the liquid outer core. After introduction of these kind of waves (Alfvèn waves, wave equation), propagation of these kind of wave is studied in the outer core, with the presence or not of an solid inner core. Last, an excitation mecanism of external origin of these waves is studied
Martin, Jean-Philippe. "Alignements de protons et neutrons h11/2 et configurations à deux quasi-particules dans le noyau 124Ba." Grenoble 1, 1988. http://www.theses.fr/1988GRE10062.
Повний текст джерелаRacca, Chantal. "Etude experimentale avec diogene des protons produits au cours des reactions alpha-noyau entre 200 et 800 mev par nucleon." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13238.
Повний текст джерелаGreff, Marianne. "Aspects theoriques de la rotation de la terre et de son noyau : influence de la viscosite." Université Louis Pasteur (Strasbourg) (1971-2008), 1991. http://www.theses.fr/1991STR13220.
Повний текст джерелаŠrámek, Ondřej. "Modèle d’écoulement biphasé en sciences de la Terre : fusion partielle, compaction et différenciation." Lyon, École normale supérieure (sciences), 2007. http://www.theses.fr/2007ENSL0444.
Повний текст джерелаFraysse, Lucien. "Production de pions avec étude des effets coulombiens et corrélations à deux pions dans les collisions néon-noyau aux énergies relativistes." Clermont-Ferrand 2, 1989. http://www.theses.fr/1989CLF2E419.
Повний текст джерелаNobili, Clément. "Etude expérimentale de l'instabilité de précession dans un sphéroïde." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0273.
Повний текст джерелаThe nature of the flow in the liquid core of the Earth and other telluric planets is a matter of interest for geophysicists since centuries. It plays an important role in the exchanges between the core and the mantle and is also the source of the magnetic field. The precession of the Earth, studied since Hipparque around the 2nd century B.C. is able to drive complex flows in the outer core. Experimental measurements are conducted in the model case of a precessing spheroid. The flow is visualised with flat reflective particles, which allow a study over a broad range of parameters. The flow is then accurately characterised with PIV measurement. Two solutions of solid body rotation well predicted by Busse theorie (1968) show two transitions to turbulence when the Ekman number decreases. Both transitions show instabilities where inertial modes are coupled by a triadic resonance. The first instability is similar to the one described in a precessing sphere and called Conical Shear Instability (CSI) by Lin et al. (2015). The second instability presents the characteristics of the CSI with inertial modes of low azimuthal wave number but also the characteristics of the elliptic instability (Lacaze 2004). Finally, a third region of instability is observed and measured in the case of prograde precession around a characteristic precession frequency
Bordeleau, Charles-Antoine. "Effet des charges lourdes sur les barrages en remblai : déformation permanente d'un noyau d'argile." Master's thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/69366.
Повний текст джерелаMonteux, Julien. "Modélisation Numérique de la Formation du Noyau Terrestre : Contribution des Impacts Météoritiques." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00363623.
Повний текст джерелаUn impact géant sur une petite protoplanète engendre une anomalie thermique sans fusion significative. Lorsque l'impacteur dépasse une taille critique, l'anomalie thermique subit d'abord une phase advective isotherme puis refroidit par diffusion. L'épaisseur de l'anomalie thermique à la fin de l'étape advective ne dépend que de la taille et des paramètres rhéologiques du corps impacté.
Lors d'un impact géant sur une protoplanète indifférenciée avec un rayon supérieur au millier de kilomètres, l'énergie apportée peut générer localement de la fusion partielle et une ségrégation entre le fer très dense et les silicates plus légers. Le fer migre ensuite vers le centre de la planète et contribue ainsi à la formation du noyau. Nous avons développé des modèles d'évolution thermique par dissipation visqueuse de la phase métallique plongeant dans du matériel indifférencié. Lorsque son volume est suffisant, le diapir de fer se réchauffe lors de sa chute vers le centre. Ce chauffage est fonction des paramètres rhéologiques de la planète impactée et notamment des contrastes de viscosité mis en jeu.
Coltice, Nicolas. "Dynamique du globe et éléments volatils." Lyon, École normale supérieure (sciences), 2001. http://www.theses.fr/2001ENSL0182.
Повний текст джерелаGarcia, Raphael François. "Le Noyau Terrestre: étude sismologique de quelques structures majeures influençant la dynamique terrestre." Phd thesis, Université Paul Sabatier - Toulouse III, 2001. http://tel.archives-ouvertes.fr/tel-00370921.
Повний текст джерелаFirsov, Ilya. "Point de vue géomagnétique sur l'écoulement et le cisaillement radial au toit du noyau terrestre." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU018.
Повний текст джерелаElectrical currents circulating within the fluid outer core of the Earth are responsible for the main magnetic field of our planet. Numerical simulations of the geodynamo have been employed to elucidate its mechanism. They can also produce synthetic data (magnetic field and fluid velocity at the core surface, angular momentum of the core), which have been used to test the techniques employed for real geophysical data. For the moment, scientists have only used the radial induction equation to study the flow dynamics near the core-mantle boundary (CMB). In this study, we have managed to also use the horizontal part of the induction equation to obtain extra constraints on the dynamics below the CMB, associated to the radial derivative of the flow (radial shear). For this, we use the property that the core magnetic field matches a potential field in the mantle. The method was tested against numerical simulations. In the case of stress-free dynamo simulations, we have recovered the expected condition of zero stress at the core surface, where the flow is equal to the radial shear.With no-slip boundary condition the flow at CMB is equal to zero and rapidly changes with depth, in the viscous boundary layer. We have developed an algorithm to define unambiguously the interior velocity field just below the viscous boundary layer from records of the velocity field within the viscous boundary layer. This makes possible to calculate the a priori information (covariance matrices for the flow coefficients) needed to estimate core surface flows from geomagnetic data.The inverse problem for the shear is ill-posed and more sensitive to the a priori information than the inverse problem for the flow. The importance of a priori information is illustrated in the results of the inversion by using two hypotheses: (1) the assumption of zero stress, where a priori information was calculated from stress-free dynamos, and where the shear is equal to the flow at the CMB, (2) the quasi-geostrophic (QG) assumption where the velocity is continued from the surface to the interior as a quasi-geostrophic vector field.The radial shear inverted from the flow just below the viscous boundary layers in a dynamo simulation calculated with the no-slip boundary condition differs from the shear directly extracted from the simulation, whatever the prior information used.From geophysical data, we found instead a reasonable agreement between the shear inverted from the flow assuming continuity of the geomagnetic secular variation with a potential field and the shear obtained by continuation of the QG part of the velocity field in the interior. The protocol to estimate the radial shear from the surface flow has been adapted to the case when there is a thin electrically conducting layer at the bottom of the mantle. This gave us new insights into the upper limit of the values of the lowermost mantle conductivity
Faure, Pierre. "Comportement des éléments lithophiles lors de la formation du noyau terrestre." Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC076.
Повний текст джерелаCore formation is a pivotal event in early Earth history, causing a major segregation of elements according to their affinity with either metal (siderophile) or silicate (lithophile) phases. The Bulk Silicate Earth (BSE) shows a depletion in siderophile elements coherent with a core differentiation within a magma ocean. The affinity of these elements is a function of the physical and chemical conditions (P, T, fo2, chemical composition) of metal-silicate differentiation. The behaviour of any one element varies over the formation of the core within the magma ocean; hence, the elemental distribution of Earth's Building Blocks between the two reservoirs cannot be reproduced by considering a unique behaviour of each element.In order to determine the concentration of an element in the core and the BSE, it is necessary to characterize the behaviour of the element and its evolution during Earth's accretion. In comparison to siderophile elements, lithophile elements form a minority of core-mantle differentiation studies so far. However, significant disagreement can be found concerning the concentrations of these elements among published models of BSE composition. It has also been proposed that a late sulphur accretion event could be responsible for a significant amount of lithophile elements (Sm, Nd, U, Th, K) entering the core. In order to determine the effect of core formation on the distribution of these elements between the two reservoirs, we performed ~60 new high-pressure, high-temperature experiments of metal-silicate partitioning for several elements (Uranium, Thorium, Rare Earth Elements (REE), Alkali elements) with the aim of better understanding their behaviour during Earth's accretion. These studies allow us to bring new constraints on Earth's accretion models and to refine our understanding of the core and BSE composition.We show that the (Th/U)BSE is better reproduced when considering EL chondrites as Earth's Building Blocks rather than EH. The same ratio allows us to constrain the maximum oxygen concentration of the core to no more than 4 wt%. We confirm that these elements play a small role in the core thermal history, with their concentration in the metal remaining negligible.We also demonstrate that the BSE cannot be enriched in Refractory Lithophile Elements (RLE) by more than 2.1 times their concentrations in CI chondrites, when the Earth is made of Building Blocks mixing in agreement with isotopic studies. This shows a clear incompatibility between several models of BSE composition and isotopic observations.The study of U, Th and REE also allowed us to re-evaluate the impact of a late sulphur event at the end of Earth's accretion, which would neither lead to fractionation of Sm and Nd nor allow a significant amount of U and Th to enter the core to start the geodynamo.Finally, we widen the range of studied elements to include volatile elements. A study on potassium shows that this element concentration in the core cannot exceed 57 ppm. The core would then contain 15% of the total K budget of the Earth. This content is highly dependent on the timing of volatilisation processes. We then propose that the Earth is a result of the accretion of already volatile-depleted building blocks. Giant impacts would have a minor role in the volatile depletion observed in the BSE today
Le, Huy Minh. "Le champ geomagnetique, les mouvements du fluide a la surface du noyau et les variations decennales de la rotation de la terre." Paris 7, 1995. http://www.theses.fr/1995PA077222.
Повний текст джерелаCurien, Dominique. "Noyaux en rotation rapide et etats extremes de la matiere nucleaire : etude des changements de forme dans les noyaux **(151)tb et **(153)dy." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13211.
Повний текст джерелаMenas, Ferhat. "Etude des changements de forme dans les noyaux en rotation." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599599h.
Повний текст джерелаAnsel, Valérie. "L'anisotropie du manteau déduite de la biréfringence des ondes de cisaillement." Paris 11, 1989. http://www.theses.fr/1989PA112376.
Повний текст джерелаMALAVERGNE, VALERIE. "Etude experimentale a haute pression et haute temperature du partage des elements de transition entre les phases du manteau et du noyau de la terre." Paris 7, 1996. http://www.theses.fr/1996PA077236.
Повний текст джерелаBazin, Daniel. "Etude de l'emission de neutrons retardes par des noyaux tres riches en neutrons et analyse des mecanismes de reaction nucleaire responsables de la production de ces noyaux." Caen, 1987. http://www.theses.fr/1987CAEN2020.
Повний текст джерелаBerthet, Sophie. "Métamorphisme d'une chondrite à enstatite nommée Indarch : implication sur les phénomènes de différenciation planétaire. Application à la Terre." Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00551310.
Повний текст джерелаCartier, Camille. "Comportement des terres rares (REE) et des éléments fortement chargés (HSFE) pendant la différenciation précoce de la Terre sous faible fugacité d'oxygène." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22525/document.
Повний текст джерелаThe Earth contains significant amounts of water and its mantle is highly oxidized compared to the solar nebula canonical conditions, which is inconsistent with the existence of its metallic core and its location in the Solar System. This implies the redox state of the Earth has increased during its early history as suggested in heterogeneous accretion models. Thus, the first building blocks of our planet would have been made of highly reduced material, and the early Earth’s differentiation (core extraction and silicate differentiation) would have taken place under highly reducing conditions (between IW-5.5 and IW-2). The aim of this thesis is to measure the impact of these conditions on rare earth elements (REE) and high field strength elements (HFSE) behavior, and model their distribution into the main reservoirs formed early in Earth’s history. We run about sixteen melting – crystallization experiments, starting from chondritic material and equilibrating it at low (5 GPa) and high (26 GPa) pressure, spanning a redox range going from IW (iron – wüstite buffer) to IW-8. In order to characterize the fO 2 parameter in these extreme conditions, we develop an adapted thermodynamic formalism, based on Si-SiO 2 equilibrium. Analyzing the various equilibrated phases within our experimental samples, we calculate and propose the first crystal (enstatite, bridgmanite = Mg-perovskite, majorite) – silicate liquid, metal – silicate, sulfide – silicate partition coefficients database for HFSE and REE under highly reducing conditions. Using our enstatite-liquid data we develop a fO 2 proxy based on D(Cr)/D(V) ratio and we measure type I chondrule fO 2 as being similar to canonical nebular conditions (IW-7). Our metal-silicate partitioning data prove that Earth core extraction is not responsible for REE fractionation. On the contrary, recording for the first time Nb 2+ and Ta 3+ XANES spectra in silicate glasses and at ppm level concentrations, we prove that Nb and Ta behavior is mainly controlled by fO 2 . Using our partitioning data in a heterogeneous accretion model, we show that sub-chondritic Nb/Ta signature of the silicate Earth (14 ± 0.3) can be the result of the accretion of chondritic material changing with time, combined with the progressive extraction of the core in reducing conditions. This refutes the hypothesis of an oxidized material building the Earth. Our high-pressure experiments show that REE and HFSE partitioning in majorite and bridgmanite is very sensitive to fO 2 . Moreover, iron dismutation process, invoked to explain mantle fO 2 increase during magma ocean crystallization, does not seem to be an efficient mechanism below IW. Finally, our data show that Ti, V, Cr, Mn, Nb and Ta are chalcophiles under highly reducing conditions. Consequently, early extraction of a sulfide melt at an early and reduced stage could have modified chondritic elementary ratios in the silicate Earth. Extraction of a substantial amount of FeS may also cause a Zr/Hf decoupling
Suer, Terry-Ann. "Partage du soufre et du platine entre un réservoir métallique et un réservoir silicaté lors de la formation du noyau terrestre." Electronic Thesis or Diss., Paris 6, 2016. http://www.theses.fr/2016PA066557.
Повний текст джерелаMeasurements of the metal-silicate partitioning behavior of siderophile and volatile elements at the conditions of the deep primitive Earth can provide constraints on the mechanisms of terrestrial core formation. Experiments were conducted in a laser-heated diamond anvil cell to investigate the metal-silicate partitioning of sulfur and platinum at high pressures and temperatures. The partitioning behaviors were quantified post-experiment by high resolution NanoSIMS imaging. Sulfur was found to be moderately siderophile at core formation conditions and this, together with cosmochemical estimates, argue that it cannot be a major light element in the core. Accretion modeling with this new partitioning data implies that a heterogeneous accretion scenario can best explain the mantle and bulk Earth sulfur contents. The measured partitioning values for platinum are such that the mantle's platinum abundance can be sufficiently explained by core-mantle equilibration. Overall these results support the hypothesis that the cores of large impactors did not equilibrate fully with the magma ocean and metal could have sequestered to the Earth's core without leaving a record in the mantle. A late sulfide segregation event also likely played a role in establishing the observed mantle compositions. These findings help to further elucidate the accretion history of the Earth and core-mantle differentiation processes
Léandri, Joseph. "La méthode des multiphonons appliquée à l'étude des états vibrationnels K = 0 dans les noyaux lourds déformés." Grenoble 1, 1987. http://www.theses.fr/1987GRE10128.
Повний текст джерелаDessagne, Philippe. "Etude de noyaux loin de la ligne de stabilite : mesures de masse et analyse de l'emission de particules retardees." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13217.
Повний текст джерелаFidah, Malika. "Détermination expérimentale des lignes YRAST des noyaux d'étain (A = 106 -108)." Bordeaux 1, 1988. http://www.theses.fr/1988BOR10622.
Повний текст джерелаLasbleis, Marine. "Dynamique et évolution de la graine terrestre." Thesis, Lyon, École normale supérieure, 2014. http://www.theses.fr/2014ENSL0962/document.
Повний текст джерелаIn the past thirty years, our understanding of the inner core structure has increased with the number of seismic studies. Observations reveal a global anisotropy with a cylindrical symmetry and radial and lateral heterogeneities. In this work, I have studied different hypothesis on the dynamics of the inner core to explain these observations. Revisiting the dynamics induced by the Lorentz force, we studied the effect of new boundary conditions, the effect of stratification and growth rate. However, the obtained flow is not strong enough to deform the media for viscosities larger than 1012 Pa.s, in the lower bound of the published inner core estimates. Deformation mechanisms can be subdivided between natural convection (arising from unstable thermal or compositional gradients) and externally forced flows, like the one induced by the Lorentz force. Recent estimates of the thermal diffusivity of iron at high pressure limit the possibility of thermal convection to an age of the inner core lower than a hundred of millions years. Two key parameters emerge for the inner core dynamics: the sign and strength of the density stratification and the viscosity of the inner core. We construct a regime diagram for the Earth’s inner core dynamics that compares the different published models in term of maximum instantaneous deformation rate. This diagram allows us to compare both expected strain rate and deformation geometry with the seismic observations. However, we find that no published model can explain all the seismic observations. The inner core anisotropy and the hemispherical dichotomy are especially difficult to reconcile with these models. The F-Layer is a 200km anomalous layer at the bottom of the outer that presents low P-Wave velocities compared to well-Mixed model. It has been interpreted as a layer depleted in light elements, whereas we usually consider that light elements are expelled at the surface of the inner core by freezing of the outer core alloy. We study the hypothesis of freezing in the bulk of the layer, with iron particles growing and settling in an increasingly depleted liquid
Perrier, Frédéric. "La mesure precise du parametre de melange electrofaible dans la diffusion de neutrinos de haute energie sur noyaux de fer." Paris 6, 1986. http://www.theses.fr/1986PA066350.
Повний текст джерелаClesi, Vincent. "Formation de la Terre et de Mars : étude expérimentale et numérique." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22750/document.
Повний текст джерелаThe formation of the metallic planetary cores is a major event regarding to the evolution of physical and chemical properties of the telluric planets as we know it today. Indeed, the siderophile elements (i.e. which has affinities with metallic phases) abundances in planetary mantles is explained by the conditions of core-mantle segregation. Among these conditions, pressure, temperature and oxygen fugacity are the main ones controlling distribution of the elements between mantle and core. This distribution can only be explained by an equilibrium between metal and silicate obtained in a deep magma ocean, which implies high pressure and high temperature of equilibrium. Moreover, the oxygen fugacity must have varied during core-mantle segregation, in a reduced-to-oxidized path most probably. Another important parameter is whether or not water is present in the primordial magma ocean. Indeed, we now have more and more lines of evidences showing that the volatile elements, especially water, arrived during accretion and therefore during the core-mantle segregation, which means that water can have an effect on the latter phenomenon. Considering this hypothesis, we performed several high pressure-high temperature experiments which allowed us to model the formation of the core under hydrous conditions. These experiments demonstrated that water has a significant effect on the redox state evolution of planetary mantles. We use this redox evolution to constrain models of planetary accretions, based on a mix of EH and CI chondrites, showing a good agreement with models based on isotopic data. The output of these models is the maximum initial concentration in water on the Earth (1.2 -1.8 %wt) and on Mars (2.5-3.5 %wt). Furthermore, these experiments showed a lithophile behavior (i.e. which has affinities with silicated phases) of hydrogen at high pressures, contrary to previous studies. Therefore, the difference between high initial concentrations in water yielded by our accretion models and the estimated actual concentrations on the Earth and Mars (2000 ppm and 200 ppm, respectively) cannot be explained by a hydrogen reservoir in the core. Finally, to improve the models of core-mantle segregation, we showed by numerical simulations the important effect of the magma ocean viscosity on the equilibrium between planetary mantles and cores. it lead us to reevaluate the models of accretion based on experimental data, especially the maximum extent of magma oceans. The evolution of the magma ocean viscosity has therefore significant implications on the final composition of planetary cores (for instance on the sulfur, oxygen and silicon content of the Earth’s and Mars’ core)
Montarou, Gérard. "Etude experimentale avec diogene de la production des deutons dans les reactions alpha-noyaux entre 200 et 800 mega-electron volt par nucleon." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF2E400.
Повний текст джерелаLe, Mevel Jean-Claude. "Contribution a l'etude du role physiologique du noyau preoptique chez la truite arc-en-ciel salmo gairdneri r. : aspects electrophysiologiques de l'activite de ce noyau et de son eventuelle implication dans des regulations fonctionnelles." Brest, 1987. http://www.theses.fr/1987BRES2013.
Повний текст джерелаHinderer, Jacques. "Sur quelques effets en rotation et deformation d'une planete a noyau liquide, manteau elastique et couche fluide superficielle." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13172.
Повний текст джерелаSilva, Luís Alexandre. "Ecoulements à la surface du noyau, secousses géomagnétiques et prédictions à court terme du champ magnétique terrestre." Paris, Institut de physique du globe, 2010. http://www.theses.fr/2010GLOB0002.
Повний текст джерелаThis thesis reports on a series of investigations directed towards the dual goal of improving our understanding of what drives the time evolution of the Earth's main magnetic field, and of improving our current ability to predict its short-term behavior. For that we first perform core flow inversions for several epochs and compute first estimates of the flow acceleration by computing differences between successive flows. These first results suggest that the flow generating the Secular Variation (SV) is not stationary. Next, we show how both the core flow and core flow acceleration can be computed simultaneously at any given epoch, if the field and its first and second time derivatives (the SV and the Secular Acceleration (SA)) are known. This allows us to unambiguously show that no stationary flow can account for the observed SA. Based on those results, we consider the possibility of improving on the short-term prediction of the field based on a linear extrapolation currently used by the International Geomagnetic Reference Field (IGRF) by using a method based on a steadily accelerated flow. Then we independently consider the possibility of increasing the spatial resolution of the predictive SV model currently used by IGRF. From all of the above, we conclude that the main limitation to shortterm predictions of the field is the occurrence of sudden changes in the SA (geomagnetic jerks). We thus investigate the type of core ow acceleration changes that are needed to account for those jerks and focus on the 2003 ge
Lleres, Annick. "Production et désexcitation de noyaux chauds dans les réactions induites par des ions lourds d'énergie comprise entre 10 et 84 MeV/nucléon sur des cibles de masse moyenne." Grenoble 1, 1988. http://www.theses.fr/1988GRE10006.
Повний текст джерелаDupieux, Pascal. "Etude des corrélations proton-proton à petite impulsion relative dans les collisions Ne + noyaux avec le détecteur DIOGENE." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21103.
Повний текст джерелаKhlaifia, Abdessattar. "Modulation de la dépression synaptique à long terme dans le noyau du tractus solitaire par le statut nutritionnel." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM5037.
Повний текст джерелаThis work joins within the framework of studies about the mechanisms of integration of the visceral informations. We studied long term synaptic depression in the nucleus of tractus solitarii (NTS) and it's modulation during changes in the nutritional status. In the first study, we characterized a long-term synaptic depression (LTD) in the NTS. This LTD, triggered by low frequency stimulation of visceral afferents is expressed at the presynaptic level. It involves release of endocannabinoids that would eventually reduce glutamate release probability. Surprisingly the postsynaptic element seems to play no role in this LTD. It requires sequential activation of NMDA receptors, the release of anandamide and activation of the cannabinoids type 1 receptors (CB1) and presynaptic activation. Our results suggest that this LTD could be entirely organized at the presynaptic compartment of visceral afferents. In the second part of this work, we were interested on the modulation of this endocannabinoïds dependent long-term depression (eCBs-LTD) by the nutritional status. Food deprivation during 24 h prevents the induction of eCBs-LTD by the stimulation of visceral afferents. These effects are mimicked by the activation of ghrelin receptors in the NTS. 3 h refeeding restores the eCBs-LTD via peripheral action of cholecystokinin (CCK) and the activation of the ERK pathway. Altogether, this work emphasizes the high plasticity of visceral afferents and its regulation by the nutritional status
Viera, Nelson. "Mesure de la masse atomique du noyau N=Z 74Rb avec le spectromètre MISTRAL." Paris 6, 2002. https://tel.archives-ouvertes.fr/tel-00002578.
Повний текст джерелаRahmani, Ahmed. "Étude avec le détecteur DIOGENE de la production de protons énergétiques dans les collisions d'ions lourds relativistes Ne + noyaux : température de la matière hadronique." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF21147.
Повний текст джерелаSuer, Terry-Ann. "Partage du soufre et du platine entre un réservoir métallique et un réservoir silicaté lors de la formation du noyau terrestre." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066557/document.
Повний текст джерелаMeasurements of the metal-silicate partitioning behavior of siderophile and volatile elements at the conditions of the deep primitive Earth can provide constraints on the mechanisms of terrestrial core formation. Experiments were conducted in a laser-heated diamond anvil cell to investigate the metal-silicate partitioning of sulfur and platinum at high pressures and temperatures. The partitioning behaviors were quantified post-experiment by high resolution NanoSIMS imaging. Sulfur was found to be moderately siderophile at core formation conditions and this, together with cosmochemical estimates, argue that it cannot be a major light element in the core. Accretion modeling with this new partitioning data implies that a heterogeneous accretion scenario can best explain the mantle and bulk Earth sulfur contents. The measured partitioning values for platinum are such that the mantle's platinum abundance can be sufficiently explained by core-mantle equilibration. Overall these results support the hypothesis that the cores of large impactors did not equilibrate fully with the magma ocean and metal could have sequestered to the Earth's core without leaving a record in the mantle. A late sulfide segregation event also likely played a role in establishing the observed mantle compositions. These findings help to further elucidate the accretion history of the Earth and core-mantle differentiation processes
Koehl, Muriel. "Conséquences à long terme d'un stress prénatal sur les substrats neurobiologiques des processus adaptatifs." Bordeaux 2, 1998. http://www.theses.fr/1998BOR28566.
Повний текст джерелаDeguen, Renaud. "Dynamique de la cristallisation de la graine : expériences et modèles." Phd thesis, Grenoble 1, 2009. http://www.theses.fr/2009GRE10051.
Повний текст джерелаSeismic observations of the Earth's inner core reveal unexpected structural complexity, its most striking property being its elastic anisotropy. The inner core has been slowly crystallizing from the liquid outer core, and its structure and dynamic may be in part related to the process of solidification. A stability analysis of the solidification front suggests that the inner core boundary is morphologicaly unstable, and that a dendritic layer should have developped. This dendritic layer may extend deep in depth, but thermosolutal convection associated with the solidification and compaction of the solid matrix are expected to efficiently expell the residual liquid. We present an experiment of solidification under a large gravity, which allows to increase the strength of the convective phenomenon associated with solidification. It is shown that the enhancement of solutal and thermal transport have important consequences on the structure of the dendritic layer, and increases significantly its solid fraction. A last part is devoted to the mechanisms from which the seismis anisotropy may originates. It is shown that the internal dynamic of the inner core depends critically on the thermal and solutal evolution of the outer core. If the inner core is relatively old, its is likely to be stably stratified, and vertical motions are inhibited. Heterogeneous growth of the inner core results in an shallow shear layer. If the inner core has grown rapidly, a thermaly driven convective episode may have occured in its early history
Fontaine, Asmaa. "Etude des équilibres chimiques dans le contexte d'accrétion et de différenciation des planètes telluriques." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22457/document.
Повний текст джерелаAbundances of siderophile elements in the mantle indicate that the Earth’s core segregated in a deep magma ocean. Yet, it is unfortunately difficult to constrain the oxidation conditions prevailing during planetary accretion based on geochemical tracers due to the number of parameters playing a role in metalsilicate partitioning. In addition, the oxidation state of terrestrial planets can evolve during accretion. The nature of the accreted material during the formation of the terrestrial planets remains then still uncertain. Our strategy to improve our knowledge in this domain is to model the chemical equilibria taking place in the primitive Earth. The equilibria can evolve (i) as P-T conditions of core-mantle segregation increase with the size of the planet, (ii) due to crystallization of the magma ocean and (iii) with accretion of heterogeneous material of different composition and oxidation state. We explored the potential role of collisional erosion in the context of Earth’s accretion from Enstatite Chondrites. For this, we refined experimentally the chemical composition of pseudo-eutectic melts as a function of pressure up to 25 GPa. We show that the first melts are highly enriched in SiO2 (up to 75 wt% SiO2) and alkali elements (Na and K). Therefore, collisional erosion of proto-crusts on EH-planetesimals can efficiently increase their final Mg/Si ratio and decrease their alkali elements budget. It can help to reconcile compositional differences between bulk silicate Earth and Enstatite Chondrites. We performed new experiments on metal-silicate partitioning of sulphur. We show that the present-day sulphur concentration of the Earth’s mantle can be explained by core-mantle equilibration in a deep magma ocean. S-addition in a late veneer (Rose-Weston et al., 2009) cannot be excluded; however, it is not required in order to reach the S-mantel abundance. Our results are consistent with the non-chondritic S-isotopic nature of the mantle (Labidi et al., 2013). We modeled the core-mantle partitioning of the light elements (S, Si, O) at high pressures and temperatures, by taking into account of their mutual chemical interactions and that with C. With 2 wt% S in the core and a C concentration ranging 0 to 1.2 wt% (as evidenced with cosmochemical studies), we found the O solubility from 1 to 2.4 wt%. This O incorporation to the core is insufficient to both allow an Earth accretion from an oxidized meteoritic material and result in a planet composed of a core with a mass equivalent to the third of its mass and a mantle with 8 wt% FeO content. Reduced conditions during coremantle segregation are also required to enhance the Si content in the core, possibly up to 5 wt% Si, to explain the super chondritic Mg/Si of the bulk silicated Earth (Allègre et al., 1995; O’Neill et al. 1998). Altogether, we find that the Earth was most likely accreted from a reduced material, such as enstatite chondrites, leading to a core composed of 2 wt% S, 0 to 1.1 wt% C, 1 wt% O and 5.5 to 7 wt% Si. We investigated the role of Mg-perovskite (the most abundant mineral of the mantle) crystallization on the oxidation state of Earth’s mantle during cooling of the magma ocean. We show that its crystallization induces a decrease of FeO content of the solid mantle as Fe is incompatible in perovskite, when it is in equilibrium with a liquid Fe-alloy at an fO2 of IW-2. At these conditions, the Fe3+ insertion is also low and constant (Fe3+/ Fetot of 21 ±4 %). Hence, the Mg-Pv crystallization cannot be responsible for a substantial increase of the Earth’s mantle oxygen fugacity during core segregation. (...)
Saint-Hilaire, Patrick. "Étude de la saturation progressive des noyaux de barrages en till compactes." Sherbrooke : Université de Sherbrooke, 2001.
Знайти повний текст джерелаDeguen, Renaud. "Dynamique de la cristallisation de la graine : expériences et modèles." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00414613.
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