Dissertations / Theses on the topic 'Nuage de phase mixte'
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Aubry, Clémantyne. "Multiplatform radar-lidar synergistic retrieval for liquid and mixed-phase clouds." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASJ008.
Clouds play an important role in the Earth's water cycle and radiation balance, and tend to cool the climate slightly. However, there are still many uncertainties about their feedbacks and their evolution in the context of global warming. In particular, mixed-phase clouds account for a significant proportion of the cloud radiative effect. They are composed of a mixture of ice crystals, supercooled water droplets and water vapor. This coexistence involves complex processes and the fraction of liquid and ice significantly affects their radiative properties. This complexity makes them difficult to represent in numerical models, which introduces significant biases. For this reason, it is crucial to better understand the microphysical processes of these clouds to reduce the uncertainties in climate and weather forecasts.To observe clouds, several instrument types exist, such as in situ probes (in direct contact with the hydrometeors) and remote sensing instruments (remote observations). Radar and lidar allow us to obtain distance-resolved information. They can be deployed onboard aircraft or satellites, providing regional and global coverage. Cloud radars work at frequencies (35 and 95 GHz) at which the reflectivity is sensitive to particle size, implying higher reflectivity for large cloud particles (ice crystals) than for small particles (water droplets). Lidars, on the other hand, usually operate between 355 and 1064 nm and are generally more sensitive to particle concentration. As a result, lidar backscatter is higher for highly concentrated particles, such as water droplets. Their synergy allows us to take advantage of the strengths and weaknesses of each instrument to retrieve cloud properties. However, these properties are not directly accessible from measurements and retrieval algorithms are therefore used to relate measurements to microphysical properties.This thesis proposes a new radar-lidar synergistic method dedicated to retrieve supercooled water, ice and mixed-phase cloud properties. Based on an existing method dedicated solely to ice clouds, a new approach has been developed to include both supercooled water and mixed-phase situations. The first step was to adapt and improve the classification used to identify the nature of the observed particles. Next, numerous adaptations have been applied to the algorithm to retrieve separately ice crystals and supercooled water properties. This approach is based on the different sensitivities of radar and lidar to the two types of hydrometeors: ice crystals dominate the radar signal while supercooled water dominates the lidar signal.To assess this new method, the retrievals are compared to in situ measurements from co-located observations and the literature. The first study compares retrievals from CloudSat-CALIPSO satellite data with collocated in situ airborne measurements. This comparison shows that the radar-lidar retrievals follow the same trend as the in situ measurements and provide promising results with mean percent error of 49 % for liquid water content and 75 % for ice water content, despite the quite different measurement scales and imperfect collocation. Additionally, this has been applied to the French and German airborne platforms RALI and HALO. These first results are promising and the collocated in situ data collected during recent campaigns can be used to further assess the algorithm and improve its parameterization
Gaussiat, Nicolas. "Mesure du contenu en eau et en glace des nuages en phase mixte par radars multifréquences." Toulouse 3, 2002. http://www.theses.fr/2002TOU30216.
Mioche, Guillaume. "Validation des produits d'inversion des observations satellitaires CALIPSO/CloudSat pour la caractérisation des propriétés optiques et microphysiques des nuages de glace et en phase mixte." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719316.
Planche, Céline. "Développement et évaluation d'un modèle tridimensionnel de nuage mixte à microphysique détaillée : application aux précipitations orographiques." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00622980.
Collombon, Mathieu. "Résonance noire à trois photons sur un nuage d'ions calcium confinés." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0017.
The work presented in this thesis describes the complete experimental set-up and approach to realize three-photon coherent population trapping in a cloud of radiofrequency confined calcium ions. The realization of such a population trapping relies on a stringent conditions of the phase relationship between the three lasers involved in the interrogation process, and also their spectral linewidths. Our experimental approach is based on the optimization of the performance of a frequency-stabilized titanium-sapphirelaser at 411 THz (729nm) at the 10⁻¹⁴ level, in term of relative frequency uncertainties. This laser’s fre-quency stability is subsequently transfered to a optical frequency comb by means of a phase-locked loop. Then the two other lasers involved (866 nm and 794 nm) are phase-locked to the optical frequency combwith the same technique. This work describes the transfer method along with its measured performances. With all the three lasers sharing the same ultra-stable frequency reference we have been able to experi-mentally observe for the first time a 3-photon dark resonance in the fluorescence spectra of the 40 Ca⁺, signature of a coherent population trapping in a 3-photon scheme. The dependence of this resonance at experimental parameters, such as laser powers, laser detunings and local magnetic field, have been studied and are presented in this work. The preliminary results have allowed to explain the behaviour of the dark resonance and explored conditions for the use of the 3-photon dark line as a THz frequency standard
Belerrajoul, Mohamed. "Modélisation multi-échelle de la combustion d'un nuage de particules." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0014/document.
The presence of fine particles of oxidizable materials is encountered in many industrial situations.The risk of dust explosion presents a constant threat in transformation industries that manufacture,use or manipulate powders or combustible materials dusts. In nuclear safety analysis, one of themain scenarios is the risk of graphite dust explosion that may occur during decommissioningoperations of Uranium Natural Graphite Gas reactors. The issue considered in this thesis isrelated to combustion of a dilute gas-particle mixture. This work aims at developing a macroscopicEuler-Lagrange model for predicting laminar flame velocity, which is one of the essential data forturbulent flame velocity models used to evaluate the risk of dust explosion. First, the macroscopicheat and mass transfer equations are derived using the volume averaging method. The majorinterest of the proposed approach is to provide closure problems that allow to estimate theeffective transport coefficients, such as heat exchange coefficients and the effective coefficient ofthe heterogeneous reaction. Second, Euler-Lagrange simulations are used to determine the planetwo-phase laminar flame velocity as a function of gas mixture and graphite dust characteristics.The proposed model is compared to the classical Euler-Lagrange model based on the resolutionof the boundary layer problem in the vicinity of an isolated particle in infinite medium. Results showthat the dilution rate and the indirect particle-particle exchanges are not systematically negligible inthe macroscopic exchanges between the two-phases. On the other hand, this study suggests thepotentiality of the proposed approach for detailed simulations of two-phase flow
Bourgeois, Julie. "Les ferrites du type RFe2O4 à valence mixte." Caen, 2012. http://www.theses.fr/2012CAEN2009.
LuFe2O4 belongs to the rare-earth ferrite family RFe2O4 (R=Dy to Lu, Y), whose structure can be described as a stacking along c of [LuO2]∞ and [Fe2O4]∞ compact layers. This compound is attracting a lot of attention nowadays because of its multiferroic properties, linked to an antiferromagnetic spin ordering below Tn=250K and a ferroelectric state, based on a polar charge ordering of Fe2+ and Fe3+ species on a triangular lattice. In this work, two samples have been thoroughly investigated, combining synchrotron X-ray, neutron and electron diffraction techniques with magnetization, transport and dielectric constant measurements, as well as Mossbauer spectroscopy. Two main points have been evidenced: a slight monoclinic distortion of the room temperature crystal structure (SG C2/m), and a new structural modulation, dependent of the oxygen stoichiometry. The magnetic ground state of LuFe2O4 at low temperature is particularly complex, with several ferrimagnetic and antiferromagnetic magnetic phases co-existing. High pressure X-ray and neutron diffraction experiments have shown that LuFe2O4 undergoes an irreversible phase transition above 8GPa at room temperature, which could be linked with a new type of charge ordering. Below TN, increasing pressure up to the experimental limit of 3GPa leads to a decrease of the intensity of the magnetic scattering signal
Maalal, Rachid. "Propriétés diélectriques et structurales de la phase d'Aurivillius mixte Bi(7)Ti(4)NbO(21)." Limoges, 1994. http://www.theses.fr/1994LIMO0030.
Sofikitis, Alexandra. "Sources et évolution des formes redox du fer en phase aqueuse atmosphérique." Paris 7, 2004. http://www.theses.fr/2004PA077171.
Rostirolla, Gustavo. "Ordonnancement dans un centre de calculs alimenté par des sources d'énergie renouvelables sans connexion au réseau avec une charge de travail mixte basée sur des phases." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30160.
Due to the increase of cloud, web-services and high performance computing demands all over the world, datacenters are now known to be one of the biggest actors when talking about energy consumption. In 2006 alone, datacenters were responsible for consuming 61.4 billion kWh in the United States. When looking at the global scenario, datacenters are currently consuming more energy than the entire United Kingdom, representing about 1.3\% of world's electricity consumption, and being even called the factories of the digital age. Supplying datacenters with clean-to-use renewable energy is therefore essential to help mitigate climate change. The vast majority of cloud provider companies that claim to use green energy supply on their datacenters consider the classical grid, and deploy the solar panels/wind turbines somewhere else and sell the energy to electricity companies, which incurs in energy losses when the electricity travels throughout the grid. Even though several efforts have been conducted at the computing level in datacenters partially powered by renewable energy sources, the scheduling considering on site renewable energy sources and its variations, without connection to the grid can still be widely explored. Since energy efficiency in datacenters is directly related to the resource consumption of the computing nodes, performance optimization and an efficient load scheduling are essential for energy saving. Today, we observe the use of cloud computing as the basis of datacenters, either in a public or private fashion. The main particularity of our approach is that we consider a power envelope composed only by renewable energy as a constraint, hence with a variable amount of power available at each moment. The scheduling under this kind of constraint becomes more complex: without further checks, we are not ensured that a running task will run until completion. We start by addressing the IT load scheduling of batch tasks, which are characterized by their release time, due date and resource demand, in a cloud datacenter while respecting the aforementioned power envelope. The data utilized for the batch tasks comes from datacenter traces, containing CPU, memory and network values. The power envelopes considered, represent an estimation which would be provided by a power decision module and is the expected power production based on weather forecasts. The aim is to maximize the Quality of Service with a variable constraint on electrical power. Furthermore, we explore a workload composed by batch and services, where the resources consumption varies over time. The traces utilized for the service tasks originate from business critical datacenter. In this case we rely on the concept of phases, where each significant resource change in the resources consumption constitutes a new phase of the given task. In this task model phases could also receive less resources than requested. The reduction of resources can impact the QoS and consequently the datacenter profit. In this approach we also include the concept of cross-correlation to evaluate where to place a task under a power curve, and what is the best node to place tasks together (i.e. sharing resources). Finally, considering the previous workload of batch tasks and services, we present an approach towards handling unexpected events in the datacenter. More specifically we focus on IT related events such as tasks arriving at any given time, demanding more or less resources than expected, or having a different finish time than what was initially expected. We adapt the proposed algorithms to take actions depending on which event occurs, e.g. task degradation to reduce the impact on the datacenter profit
Michaud, Franck. "Diffusion multiple de la lumière en présence de gain dans un nuage d'atomes froids : vers un laser aléatoire." Nice, 2008. http://www.theses.fr/2008NICE4055.
The random laser is a new tape of laser, whose feedback mechanism is provided by multiple scattering, in a random medium with gain. Our projet is to produce such a laser, with 85Rb cold atoms trapped in a magneto-optical trap, as gain and scattering medium. In this thesis, we present several process of gain in cold atoms, which we have studied theoretically and experimentally : Mollow gain, Raman Gain, and Four-wave Mixing. Each type of these gain, permit us to produce a classical laser, putting a Fabry-P´erot cavity around the atomic cloud. A study is already led on multiple scattering in presence of gain, in a preliminary part of the realization of a random laser
Bianco, Angelica. "Formation photoinduite du radical hydroxyle dans la phase aqueuse du nuage : impact sur les acides carboxyliques et les acides aminés." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22746/document.
Clouds represent a multiphase complex and reactive medium in which gases, liquid particles and aerosols are in continuous interaction. A large fraction of atmospheric chemical compounds present in the particulate and gaseous phases can be transferred to the cloud droplets where can undergo chemical, photochemical and microbiological transformations. Cloud waters were sampled at the puy de Dôme station. The first part of my PhD work is focused on the photoreactivity of cloud water. Formation of a reactive species such as hydroxyl radical, by direct photolysis of inorganic sources was investigated, as well as the correlation between the concentration of sources and the hydroxyl radical formation rate. The spectroscopic proprieties and fate of tartronic acid, were investigated under cloud water conditions. Moreover, photochemical experiments were performed using continuous irradiation (direct and hydroxyl radical mediated photolysis) and nanosecond flash photolysis in order to assess the reactivity of this compound in cloud aqueous phase. The second part of my work is centered on the characterization of organic matter in clouds. Two studies are presented: i) Detection and quantification of tryptophan by fluorescence spectroscopy and the assessment of its reactivity; ii) detection and quantification of amino acids. Amino acids are detected for the first time in cloud water using a derivatization method and this work show that they represent the 9% of the dissolved organic matter in cloud. Their reactivity with hydroxyl radical was compared to the reactivity of carboxylic acids and dissolved organic matter. These results clearly demonstrate that amino acids represent a major sink of hydroxyl radicals in cloud water
Oulaid, Othmane. "TRANSFERT COUPLÉ DE CHALEUR ET DE MASSE PAR CONVECTION MIXTE AVEC CHANGEMENT DE PHASE DANS UN CANAL." Phd thesis, Université de Sherbrooke, 2010. http://tel.archives-ouvertes.fr/tel-00669024.
VAN, QUYNH ALEXANDRA. "Résonance magnétique nucléaire dans la phase mixte des composés organiques de la famille k-(BEDT-TTF)2CuX." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10107.
Curtet, Jean-Pierre. "Structure et micro-structure d'une nouvelle famille de copolyimides alternés à conduction mixte." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10144.
Belmonte, Mylène. "Automatisation intégrale de la ligne 1 : étude et modélisation du trafic mixte." Compiègne, 2008. http://www.theses.fr/2008COMP1752.
The current thesis takes place in the framework of fine 1 automation project. It is a project that consists of upgrading fine 1 (with drivers on-board) to unattended train operation (no drivers or agents on-board) without service interruption. It results a mixed fleet operation for a period of two years between manually driven trains and driverless ones. In this context, my research work consists of continuing in a first step the development of software destined to study and analyse the mixed fleet operation on fine 1. Once operational; the model has served as a simulation in two case studies that I elaborate in a second step. These two case studies aim to answer problematical matters affecting the management of the mixed trains running inside the terminal stations. They take into account two opposite constraints: people-staff safety on one hand and quality of service offered to passengers on the other hand. The analysis and the results of these two case studies will be described in the current PhD report
Bibes, Manuel. "Elaboration et étude de couches minces de manganites à valence mixte." Phd thesis, INSA de Toulouse, 2001. http://tel.archives-ouvertes.fr/tel-00005931.
1. Le plus gros effort experimental a consisté à mettre au point et automatiser un bâti de croissance de couches minces par pulvérisation cathodique. Ce système comprend une chambre à vide dont l'atmosphère est contrôlée par deux pompes, des électrovannes et des fluxomètres. Les différentes éléments (chaufferettes porte-substrats, magnétrons, etc) sont pilotés par un ordinateur de sorte que la croissance de couches et d'hétérostructures est entièrement automatisée.
2. La seconde partie du travail a concerné l'étude et l'optimisation des conditions de croissance de couches minces nanométriques de La2/3Ca1/3MnO3. L'influence des différents paramètres de croissance (température, vitesse de dépôt, etc) sur les propriétés du matériau ont été étudiées de façon exhaustive afin de maîtriser la croissance de couches de haute qualité avec une bonne reproductibilité.
3. La majeure partie du travail a consisté à étudier l'influence des interfaces sur les propriétés physiques de couches minces de manganite. L'interaction responsable du ferromagnétisme de ces matériaux est très sensible aux distorsions structurales ce qui, combiné à la forte polarisation de spin des porteurs, donne lieu à une forte magnétorésistance à champ faible dans des poudres nanométriques (contenant une grande densité de joints de grains). Cette forte polarisation de spin conduit aussi à l'observation de forts effets magnétorésistifs dans des jonctions tunnel à base de manganites. Dans ce cadre, notre contribution consiste à étudier plusieurs types d'interfaces (joints de grains d'orientation contrôlée dans des couches texturées, défauts générés par irradiation laser, jonctions bicristallines) et a corréler les propriétés magnétiques et de magnétotransport avec les caractéristiques structurales. L'influence de l'interface avec le substrat isolant (SrTiO3, LaAlO3, NdGaO3) a également été étudiée via la dépendence en épaisseur (2.4 - 180 nm) des propriétés de couches minces totalement contraintes. Parmi les effets les plus marquants, on observe une forte diminution de la Tc et une aumgentation de la résistivité lorsque l'épaisseur diminue. Nous avons montré que cela résulte d'une séparation de phase entre des régions nanométriques ferromagnétiques-métalliques, ferromagnétiques-isolantes et non-ferromagnétiques-isolantes présentes à l'interface couche-substrat. Par ailleurs, nous avons également effectué des mesures de magnétorésistane anisotrope et d'effet Hall extraordinaire. L'amplitude de ces deux effects a été comparée et interprétée en fonction du couplage spin-orbite et des propriétés électroniques près de Tc.
Boumaza, Mohamed Seghir. "Etude par resonance magnetique nucleaire de transitions de phase dans des complexes a transfert de charge a empilement mixte." Rennes 1, 1988. http://www.theses.fr/1988REN10053.
Boumaza, Mohamed Seghir. "Etude par résonance magnétique nucléaire de transitions de phase dans des complexes à transfert de charge à empilement mixte." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376120738.
Progent, Frédéric. "Électrochromatographie capillaire : évaluation d'une nouvelle phase stationnaire mixte et application à l'analyse de peptides et à l'établissement de cartes peptidiques." Paris 11, 2005. http://www.theses.fr/2005PA114806.
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.
The 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
Progent, Frédéric. "Électrochromatographie capillaire. Evaluation d'une nouvelle phase stationnaire mixte et application à l'analyse de peptides et à l'établissement de cartes peptidiques." Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00010881.
RIOU, DIDIDER. "Analyse des proprietes structurales et magnetiques de diphosphates a charpente mixte. Etude cristallographique de la phase incommensurable banip#2o#7." Caen, 1990. http://www.theses.fr/1990CAEN2023.
Nogueira, Isabel. "Transformations des couches superficielles des matériaux induites par la phase de rodage lors de régimes de lubrification mixte et limite." Paris, ENSAM, 2004. http://www.theses.fr/2004ENAM0001.
During certain working stages of mechanical components such as guiding parts or gear-wheels, the thickness of the oil film can not be sufficient to separate totally the surfaces. The summits of the asperities can be in contact, increasing wear and friction. This situation with a discontinuous film is classically defined as mixed or limited lubrication. In that case, the forces are supported partially by the solids and by the lubricant film. Such situations can occur during the starting and stopping stages, accidental overloads and especially during the running-in. These situations are critical for the mechanical components in particular for their working life and performance in service. The contact problem between solid surfaces has been studied in this work in order to clarify the complexity of the running-in in contact working in mixed lubrication. Firstly, a study of dry contact without sliding has been carried out analysing the geometrical variation of the rough surface and the physical alterations caused by a normal load. Secondly, the influence of the lubricant and the sliding motion on the friction and wear are introduced to study the mixed and boundary lubrication. The tests have been conducted using a pin-on-disc tribometre. The influence of a friction modifier added in to the base oil has been analysed depending on the friction, the wear and the superficial alterations
Bonanno, Laurent Michel. "Analyse des phospholipides et des protéines du surfactant pulmonaire : intérêt d'une phase mixte silice/C18 dans la séparation d'un mélange complexe." Paris 11, 1991. http://www.theses.fr/1991PA114832.
Vaills, Yann. "Contribution à l'étude des transitions de phase structurales des pérovskites CsCaCl3 et CsPbCI3 par résonance paramagnétique électronique de l'ion Gd3+." Paris 6, 1986. http://www.theses.fr/1986PA066149.
Caniaux, Guy. "Paramétrisation de la phase glace dans un modèle non hydrostatique de nuage : application à une ligne de grains tropicale : [thèse en partie soutenue sur un ensemble de travaux]." Toulouse 3, 1993. http://www.theses.fr/1993TOU30071.
Lale, Adem. "Architectures d'intégration mixte monolithique-hybride de cellules de commutation de puissance sur puces multi-pôles silicium et assemblages optimisés." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30174/document.
Currently, the standard 2D hybrid power module (power converter) is the reference technology for the medium and high power market. This hybrid power module is a discrete multi-chip case. The semi-conductor chips are interconnected by wire-bonding to form switching cells. The wire-bonding interconnection technology is a limiting factor in terms of electrical and thermomechanical performances, three-dimensional integrability and productivity. The aim of this thesis is to study new architectures of very integrated power converters. Compared to the so-called hybrid reference technology, the proposed architectures aim at a greater degree of integration, with an integration at both the semi-conductor level (monolithic integration) and the packaging level (hybrid integration). Monolithic integration consists in integrating switching cells into new multi-terminal macro-chip architectures. Hybrid integration consists in developing of new technologies to assemble these macro-chips. To validate the different proposed integration architectures, the first step was to study and validate the operating modes of the new chips by SentaurusTM TCAD simulations. Then, the multi-terminal chips were realized in the micro and nanotechnology platform of LAAS-CNRS laboratory. Finally, the chips were bonded on PCB substrates to realize power converter circuit prototypes. The highly integrated switching loop presents a stray inductance loop lower than one nanohenry, wich is an important improvement as compared to the values reported in literature (about 20 nH)
Sortais-Soulard, Céline. "Équilibres oxydo-réducteurs dans les dichalcogénures de platine et de palladium : influence de la pression sur la redistribution du nuage électronique." Phd thesis, Université de Nantes, 2004. http://tel.archives-ouvertes.fr/tel-00007453.
Hamdi, Alaoui Moulay Ahmed. "Étude thermodynamique et structurale des phases bidimensionnelles à plus d'un constituant physisorbées sur graphite : cas du film mixte krypton-méthane." Nancy 1, 1994. http://www.theses.fr/1994NAN10045.
Trochut, Sylvie. "Etude de l'élaboration d'hétéroscultures InP/InGaAs/InP par la méthode d'épitaxie en phase vapeur-hydrures : application à la réalisation de photodiodes." Paris 6, 1986. http://www.theses.fr/1986PA066148.
Joo, Gi-Tae. "Nouvelles phases ferroélectriques non stoechiométriques de type perovskite ou LiTaO3." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1986. http://tel.archives-ouvertes.fr/tel-00203505.
Ascon, Dolorès. "Caractérisation des activités métaboliques des bactéries lactiques en cultures pures et mixtes par impédancemétrie et chromatographie gazeuse "headspace"." Compiègne, 1994. http://www.theses.fr/1994COMPD757.
Rombourg, Romain. "Analyse, modélisation et détection de bruits pour scanners laser terrestres." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAM064.
In this thesis, we focused on several topics related to noise detection in point cloud generated by Terrestrial Laser Scanners (TLS). First, the projection methods to compute an image from a TLS scan. Second, the detection of sky noise, i.e. noise produced when a Amplitude Modulated Continuous Wave TLS measures range only from background radiation. And finally, the detection of mixed point noise, i.e. points acquired when the TLS was receiving return signals from several different surfaces. To tackle these challenges, we first analysed how the TLS samples space and deduced properties on how the local point cloud density evolves with respect to the elevation, this allowed us to show the limits of usual noise detection techniques and oriented our focus on 2D non density based detection techniques. We then defined a theoretical framework to analyse projection methods, unavoidable foundations for 2D detection methods. This framework allowed us to bring to light two fundamental properties that should be satisfied by a projection. Following these properties, we designed a projection algorithm that satisfied them as much as possible. We then defined a way to quantify projection quality and compared our proposed algorithm with the widely used classic algorithm and showed that the classic projection method is not adapted. Our proposed projection however showed very good results. Since the sky noise was never studied in previous works, we formally analysed it to build some theoretical foundations for sky detection. The analysis allowed us to show theoretically and experimentally that the range distribution of sky noise is independent of the underlying properties of the background radiation signal. From our projection and the discovered properties, we designed a sky detector and a mixed point detector. The detectors were tested via an extensive validation in controlled conditions. The results showed that our proposed detectors combined with the proposed projection are able to correctly detect almost all presented noise with few bad detection for the sky detectors and reasonable amount for the mixed point detector
Yahiaoui, Mohamed. "ETUDE DU DIAGRAMME DE PHASE ET DU COMPORTEMENT VERRE DE SPIN DU SYSTEME ISOLANT DILUE FexMg1-xBr2." Toulouse, INSA, 1988. http://www.theses.fr/1988ISAT0014.
PIMENTA, MARCOS ASSUNCAO. "Transitions de phase a haute temperature et conduction ionique dans likso:(4) et composes apparentes." Orléans, 1987. http://www.theses.fr/1987ORLE2045.
Razafitianamaharavo, Angelina. "Étude structurale du film de cyclohexane physisorbé sur graphite : Étude thermodynamique et structurale du film mixte (krypton-cyclohexane) physisorbe sur graphite." Nancy 1, 1989. http://www.theses.fr/1989NAN10080.
Long, Yoann. "Modélisation des processus physico-chimiques nuageux : études de la réactivité de la matière organique." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00856269.
Bouchneb, Kerkoub Maroua. "Synthèse sol-gel non hydrolytique de catalyseurs stables pour l’hydrogénation en phase aqueuse de substrats biosourcés." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS147.
For a more environmentally friendly process, the hydrogenation of biosourced platform molecules such as succinic acid has to be carried out in the aqueous phase. Considering the harsh reaction conditions (160 °C, 150 bars H2, acid aqueous medium), the design of new, highly stable catalysts is needed. The most active and selective catalysts described for the aqueous phase hydrogenation of succinic acid to 1,4-butanediol are based on palladium promoted by rhenium, impregnated on a TiO2 anatase support. In this thesis, the non-hydrolytic sol-gel process has been used to prepare different oxide and mixed oxide supports based on TiO2 and ZrO2, which are the most stable oxides under hydrothermal conditions. This process allowed the one-step synthesis of high specific surface area mesoporous supports with a controlled crystalline structure and composition. In particular, we showed that it was possible to prepare “promoted supports” (TiO2-Re2O7, TiO2-MoO3, ZrO2-Re2O7, ZrO2-MoO3), incorporating the transition metal promoter, which migrates toward the surface during the calcination. Our hypothesis was that this approach would lead to a better dispersion and possibly a better stability of the promoter, and thus to a more efficient catalyst. The first catalytic tests carried out by our partners at IRCELYON showed that the Pd-based catalysts obtained with our promoted TiO2 supports were more selective and more active than the equivalent catalysts prepared by impregnation from Pd. Then the promoter on a TiO2 support, which seems to validate our initial hypothesis. Catalysis tests on the promoted ZrO2 and ZrO2 substrates are ongoing
Liu, Yao. "Etudes des impacts de la réactivité en phase aqueuse atmosphérique sur la formation et le vieillissement des Aérosols Organiques Secondaires sous conditions simulées." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10030/document.
This work focused on the impacts of aqueous phase OH-oxidation of methacrolein, methyl vinyl ketone on the SOA formation, and impacts of aqueous phase OH-oxidation on aging of SOA that are formed by isoprene, -pinene and 1,3,5-trimethylbenzene in gas phase. The chemical characterization of aqueous phase was performed by different analytical techniques. The results show the formation of small primary and secondary reaction products that were explained by suitable chemical reaction mechanisms. The formation of oligomers with high molecular mass (compared with their precursors) has also been observed during the OH-oxidation. These oligomers might be low volatile compounds that induce the formation of SOA during water evaporation. Their capacity to form SOA was experimentally demonstrated by nebulizing the aqueous phase solution at different reaction times. The results show that at least a part of oligomers remains in the particle phase during water evaporation, and contributes to the SOA formation. All of these results highlight that aqueous phase reactivity could induce important effects on the formation and aging of atmospheric SOA, which can induce modification of physico-chemical properties of SOA
Lorenzo-Diaz, José-Emilio. "Etude par diffusion de neutrons des transitions de phase dans les composés quasi-unidimensionnels (TaSe4)2I et (NbSe4)3I." Grenoble 1, 1992. http://www.theses.fr/1992GRE10184.
Giroud, Monique. "Etude expérimentale de supraconducteurs magnétiques : diagramme de phase de HoMo6S8 monocristallin et supraconductivité induite dans l'état ferromagnétique." Grenoble 1, 1987. http://www.theses.fr/1987GRE10123.
Mint, brahim Maimouna. "Méthodes d'éléments finis pour le problème de changement de phase en milieux composites." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0157/document.
In this thesis we aim to develop a numerical tool that allow to solve the unsteady heatconduction problem in a composite media with a graphite foam matrix infiltrated witha phase change material such as salt, in the framework of latent heat thermal energystorage.In chapter 1, we start by explaining the model that we are studying which is separated in three sub-parts : a heat conduction problem in the foam, a phase change problem in the pores of the foam which are filled with salt and a contact resistance condition at the interface between both materials which results in a jump in the temperature field.In chapter 2, we study the steady heat conduction problem in a composite media withcontact resistance. This allow to focus on the main difficulty here which is the treatment of the thermal contact resistance at the interface between the carbon foam and the salt. Two Finite element methods are proposed in order to solve this problem : a finite element method based on Lagrange P1 and a hybrid dual finite element method using the lowest order Raviart-Thomas elements for the heat flux and P0 for the temperature. The numerical analysis of both methods is conducted and numerical examples are given to assert the analytic results. The work presented in this chapter has been published in the Journal of Scientific Computing [10].The phase change materials that we study here are mainly pure materials and as a consequence the change in phase occurs at a single point, the melting temperature. This introduces a jump in the liquid fraction and consequently in the enthalpy. This discontinuity represents an additional numerical difficulty that we propose to overcome by introducing a smoothing interval around the melting temperature. This is explained in chapter 3 where an analytical and numerical study shows that the error on the temperature behaves like " outside of the mushy zone, where _ is the width of the smoothing interval. However, inside the error behaves like p " and we prove that this estimation is optimal due to the energy trapped in the mushy zone. This chapter has been published in Communications in Mathematical Sciences [58].The next step is to determine a suitable time discretization scheme that allow to handle the non-linearity introduced by the phase change. For this purpose we present in chapter 4 four of the most used numerical schemes to solve the non-linear phase change problem : the update source method, the enthalpy linearization method, the apparent heat capacity method and the Chernoff method. Various numerical tests are conducted in order to test and compare these methods for various types of problems. Results show that the enthalpy linearization is the most accurate at each time step while the apparent heat capacity gives better results after a given time. This indicates that if we are interestedin the transitory states the first scheme is the best choice. However, if we are interested in the asymptotic thermal behavior of the material the second scheme is better. Results also show that the Chernoff scheme is the fastest in term of calculation time and gives comparable results to the one given by the first two methods.Finally, in chapter 5 we use the Chernoff method combined with the hybrid-dual finiteelement method with P0 and the lowest order Raviart-Thomas elements to solve thenon-linear heat conduction problem in a realistic composite media with a phase change material. Numerical simulations are realised using 2D-cuts of X-ray images of two real graphite matrix foams infiltrated with a salt. The aim of these simulations is to determine if the studied composite materials could be assimilated to an equivalent homogeneous phase change material with equivalent thermo-physical properties. For all simulationsconducted in this work we used the free finite element software FreeFem++ [41]
Stephan, Pascal. "Contribution a la realisation de composants optoelectroniques integres sur inp." Paris 6, 1987. http://www.theses.fr/1987PA066215.
Zambon, Daniel. "Etude structurale et optique de la phase linay::(2)f::(8) : tb**(3+), eu**(3+), mecanisme de transfert tb**(3+) -> eu**(3+)." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21088.
Khaïroun, Slimane. "Caractérisation du palladium (+III) dans quelques phases fluorées. Etude des transitions de phases dans la structure elpasolite." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1985. http://tel.archives-ouvertes.fr/tel-00203024.
Junker, Michel. "Etude et optimisation des propriétés optiques et morphologiques d'un luminophore du type La1-x-yCexTbyPO4." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1995. http://tel.archives-ouvertes.fr/tel-00843196.
Rouède, Denis. "Contribution a l'etude des reseaux de phase photoinduits dans un cristal de bi : :(12) si o::(20)." Paris 6, 1987. http://www.theses.fr/1987PA066206.
DUPONT-NIVET, ERIC. "Epitaxie en phase vapeur aux organometalliques de gainp et algainp sur gaas : application a la realisation de diodes et de lasers a heterojonctions." Paris 7, 1987. http://www.theses.fr/1987PA077108.
Lambert, Jean-François. "Cristallogénèse et caractérisation physico-chimiques et optiques des matériaux semiconducteurs AIn2Te4 (A = Cd, Zn et Mn). Leurs potentialités comme modulateurs dans la bande spectrale 1,06-10,6 micromètres." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00136625.