Dissertationen zum Thema „Surfondues“
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Alary, Thomas. „Étude de l'impact de gouttes surfondues sur une paroi“. Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0008.
Der volle Inhalt der QuelleFlight safety is a prerequisite in aeronautics and icing is one of the main sources of incidents. The accretion of ice created by the collision of supercooled water drops in clouds can deteriorate the aerodynamic performance of the aircraft, obstruct sensors or damage engines. It is therefore essential to understand the phenomenon of water droplet impact in icing conditions to be able to predict the amount of ice that can form and to ensure sufficient sizing of ice protection systems. This phenomenon has been extensively studied in the literature but only for low drop impact speeds. ONERA's new icing wind tunnel has allowed access to drop impact regimes more in line with the reality encountered by aircraft. This thesis focuses on the impact of a water drop on a wall for Weber and Reynolds numbers that vary respectively from 15,000 to 170,000 and from 11,000 to 45,000. The study of the impact of the water drops was carried out thanks to a detection and visualization system of those then with a Phase Doppler Analyser to characterize the secondary drops created during the impact. The impact on a dry and horizontal surface was studied but other parameters such as the impact angle, the surface condition, the gas pressure, the temperature were studied to quantify their influence on the splashing. It was shown that for the investigated Reynolds and Weber number ranges, the splashing result depends on the surface properties but also on the air properties. Low air pressure or the presence of ice on the wall promotes the formation of a fluid corona that splashes off after impact. The measurement campaign with the PDA has shown that the secondary drops generated during a corona splash are larger than for a prompt splash. The impact model of Riboux and Gordillo, which attributes the splashing to an aerodynamic force exerted on the fluid that spreads during the impact, allows to describe the splashing well. A second series focusing on the ice forms obtained during the impact of SLD allowed to validate the new constants of the deposition rate model of Trontin and Villedieu determined thanks to new data from the literature
Stiti, Mehdi. „Modélisation et développement de diagnostics optiques pour la caractérisation de gouttes surfondues en écoulement ou en interaction avec un substrat sous-refroidi“. Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0120.
Der volle Inhalt der QuelleIcing phenomena that occur on aircraft in flight can be a major hazard in aeronautics. The main resulting safety problems are reduced visibility, pitot tube blockage and reduced aerodynamic performance. In this context, aircraft must be certified for various icing conditions likely to be encountered, particularly in relation to the presence of supercooled droplets with diameters greater than 50 µm in the atmosphere. The certification stages are carried out using standardised icing wind tunnel tests that make it possible to recreate aeronautical icing conditions close to those encountered in flight. The objectives of the work presented in this manuscript concern the implementation of a new optical technique based on Laser-Induced Fluorescence (LIF) for the characterization of supercooled droplets: temperature, detection of their states (i.e. liquid, solid or mixed), characterization of drops in mixed phase and dynamic of the solidification front in a droplet impacting a subcooled substrate. A first LIF technique, using two fluorescent tracers and three spectral bands of detection, allows to measure the temperature of supercooled droplets in flow as well as to estimate the fraction of ice contained in a population of droplets in flow. Measurements carried out in conditions similar to those encountered in aeronautics were performed in an icing wind tunnel of the DGA Essais-Propulseurs and showed the difficulty of reproducing real aeronautical icing conditions (droplets in thermal equilibrium with the carrier phase). A second technique based on Laser Induced Fluorescence Fast Imaging (PLIF) was developed to study the solidification of a droplet impacting a subcooled substrate. This new PLIF method provides, for the first time, access to the dynamics and morphology of the solidification front inside the droplet.The study focused on droplet impacts on a dry substrate and on a substrate covered with an ice layer. The second case allows to get rid of the phenomenon of water supercooling and thus of the random character of the solidification triggering. The measurements showed that the evolution of the solidification front and the characteristics of the tip formed by the droplet at the end of solidification were dependent on the nature of the substrate (thermal conductivity) and the angle of contact between the droplet and the substrate
Dehaoui, Amine. „Viscosité de l'eau surfondue“. Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10172/document.
Der volle Inhalt der QuelleWater is an omnipresent liquid, indeed secrets of water are uncountable. In the water case, the behaviour of many thermodynamical and dynamicalquantities is very different from other standard liquids. This difference is more important in the supercooled state. In this thesis we focus on the viscosity of the heavy and light water into the supercooled state at atmospheric pressure. To do this we use the differential dynamic microscopy method. We were able to measure the viscosity to -34 C for light water and -25°C for heavy water. These viscosity measurements correlated to measurements of self-diffusion coefficient allowed us to confirm the existence of a so-called anomaly violation Stokes-Einstein
Maabou, Serge. „Eau surfondue et (bi)polarons dans les nanostructures“. Angers, 2006. http://www.theses.fr/2006ANGE0023.
Der volle Inhalt der QuelleWe investigate the presence of dynamical heterogeneities in supercooled water with molecular dynamics simulation. The new water model TIP5P proposed by Mahoney and Jorgensen which reproduces well water properties is used. We validate our simulation by a compartive study of our results and those obtained in experiments. Thereafter, We show the existence of dynamic heterogeneities in supercooled water. We then studied dynamic aggregations of the molecules of different mobilities and find a string-like dynamics for the most mobile molecules and also dynamical aggregation of the least mobile molecules. The two kinds of dynamical aggregation appear however to be very different. We observes two different times characteristic associated to the two types of heterogeneities. Many sizes of boxes are used for simulations and we show the finite size effect on static and dynamic properties of supercooled water. In the second part of this work, we studied the properties of the charge carriers in mesoscopic structures type OD, 1D, 3D. Using Feynman variational method we carry out theoretical calculations of the characteristics (energy and mass) of the (bi)polaron in nanostructures. We obtain the relation between these characteristics, radius, anisotropy and the Fröhlich electron-phonon coupling constant. By numerical optimization, we obtained that the ground state energy and mass of (bi)polaron increase with the coupling constant and confinement frequency. We developed a theory of photoluminescence assisted by phonons in a spherical nano crystal for various mechanisms of interaction between the electrons and the phonons
Brun, Coralie. „Des liquides surfondus aux verres : étude des corrélations à et hors équilibre“. Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00664998.
Der volle Inhalt der QuelleRibeiro, Joao-Paulo. „Contribution à l’étude thermique et dynamique de la cristallisation de l’eau surfondue“. Pau, 2007. http://www.theses.fr/2007PAUU3027.
Der volle Inhalt der QuelleSince the confirmation of the refrigerants contribution to the environmental problems, techniques develop to reduce their impact, in particular by the use of a secondary fluid in refrigeration plants. Among the methods of production of such a fluid, there is that based on the crystallization of water at the supercooling breakdown. In order to control the performances of them, knowledge on the phenomenological aspects of supercooling breakdown are necessary, and more particularly on the dynamic and thermal effects. In this context, the work presents experimental studies on the supercooling breakdown. Initially, visualizations allowed to observe the way in which ice slurry is obtained. In the second time, a study of the crystallization of a mass of water subjected to various degrees of supercooling in a capillary channel permit to analyze the thermal aspect of the phenomenon and the dynamic evolution of the interface liquid-solid. In a last part, the development of a model describing the thermal and dynamic phenomena which appear at the supercooling breakdown is presented
Zouzou, Nichet Alexandre. „Modélisation de la congélation d'un film fluide soumis à une précipitation surfondue /“. Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1996. http://theses.uqac.ca.
Der volle Inhalt der QuelleSimard, Luc. „La production d'eau surfondue dans un évaporateur hélicoïdal exploitant l'ébullition par film mince“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ42015.pdf.
Der volle Inhalt der QuelleAubry, 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.
Der volle Inhalt der QuelleClouds 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
Dufour, Jacques. „Développement d'un dispositif de viscosimétrie par cisaillement téléscopique : application à l'étude des liquides sous refroidis“. Lyon 1, 1996. http://www.theses.fr/1996LYO10003.
Der volle Inhalt der QuelleGauthier, Laurent. „Exemple d'étude structurale et dynamique en phase liquide et liquide surfondu : quinoléine et lépidine“. Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10151.
Der volle Inhalt der QuelleKadiri, Yasser Bretonnet Jean-Louis Jakse Noël. „Contribution à l'étude des effets à trois corps sur la structure et la thermodynamique des liquides surfondus et amorphes“. [S.l.] : [s.n.], 2001. ftp://ftp.scd.univ-metz.fr/pub/Theses/2001/Kadiri.Yasser.SMZ0136.pdf.
Der volle Inhalt der QuelleDumas, Olivier. „Étude de la croissance du grain équiaxe dans les alliages surfondus : application à l'alliage Ag-Cu“. Grenoble INPG, 1996. http://www.theses.fr/1996INPG0196.
Der volle Inhalt der QuelleGibout, Stéphane. „Méthodes inverses de calcul appliquées à l'étude des transferts thermiques lors de la cristallisation de liquides dispersés surfondus“. Pau, 2001. http://www.theses.fr/2001PAUU3035.
Der volle Inhalt der QuelleMerabia, Samy. „Hétérogénéités dynamiques dans les liquides surfondus : transition vitreuse dans les films fins, vieillissement : propriétés mécaniques des élastomères chargés“. Paris 11, 2004. http://www.theses.fr/2004PA112274.
Der volle Inhalt der QuelleWe show that the heterogeneous nature of the dynamics near the glass transition allows to interpret in an unified view the dynamics of supercooled liquids in the bulk and in thin films, at equilibrium and out of equilibrium (aging) and also to understand the mechanical properties of filled elastomers( rubbers). We have first calculated, within the Long and Lequeux model, the length scale and the relaxation time distribution associated with the dynamical heterogeneities. This has allowed us to interpret quentitatively small probes diffusion experiments near the glass transition. In the case of thin films, we have described in details the relaxation mechanisms that take place near the glass transition and in particular we have predicted the glass transition temperature Tg as a function of the thickness of the film and the interaction energy between the polymer and the substrate. Next, we have predicted the evolution of the microscopic state of the system during a temperature jump or after a pressure jump. We have shown that the same physical mechanism allows to interpret: 1) the dependance of the equilibrium dominant relaxation time in the mean density and in the temperature 2) the melting kinetics of a glassy polymer 3) the evolution of the volume during a positive temperature jump (Kovacs effect). Finally, in the continuity of this work, we have proposed a physical model for filled elastomers. This model accounts for the reinforcement properties of the system, both in the linear and in the non linear regime and for the plastic behaviour (in the non-destructive regime of deformation)
Le, Grand Arnaud. „Etude de la dynamique de différents liquides surfondus par diffusion de la lumière à température et pression variables“. Paris 7, 2005. http://www.theses.fr/2005PA077148.
Der volle Inhalt der QuelleKadiri, Yasser. „Contribution à l'étude des effets à trois corps sur la structure et la thermodynamique des liquides surfondus et amorphes“. Metz, 2001. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2001/Kadiri.Yasser.SMZ0136.pdf.
Der volle Inhalt der QuelleThis thesis is devoted to the study of the three-body interactions on the structural and thermodynamic properties, during liquid-supercooled liquid and liquid-amorphous transformations. In this work, we use molecular dynamics simulations that gives a direct acces to the physical properties from the interactions. Therefore, both the theoretical developments and the potential can be tested by comparison with the experiment. In order to increase the accuracy of the calculations, we handled a large number of particle using a parallel version of the molecular dynamics code with a spatial decomposition of the simulation box. Our study was fisrt applied to rare gases, namely argon, krypton and xenon. The interactions between atoms, wich are dipolar in origin, are described by the Aziz and Slaman (AS) pair potential combined to the Axilrod-Teller (AT) three-body potential. It is well known that this model (AS+AT) is adapted to the study of these systems. As the AS and AT potentials cand be separated, we were able to show its influence in the liquid, supercooled and amorphous states as well as on the vitreous transition temperature Tg. In particular, the AT potential has the effect of increasing TG for all the rare gases. Thus, its use does not contradict the law of the corresponding states, wich confers an universal character on the AS+AT model for the rare gases. We also study liquid and supercooled silicon as well as liquid germanium with the Stillinger-Weber (SW) potential, wich contains both the two- and the three-body contributions. For these covalent materials, the three-body interactions are preponderant and can not be separated from the pair potential. For silicon, we have modified the SW parameter, allowing us to describe with a good accuracy the structure in supercooled states, compared with recent experiments. We were able to show that the double shoulder on the pair correlation function in this states should be accompanied by a strong increase of the density. For germanium, we have modified the parameter of the potential SW, wich controls the relative importance of the two- and three-body potentials, to obtain a good prediction of the melting point. This parameterization predicts correctly the structural properties and opens the way for a more complete study of this system
Carmona, Patrick. „Etude des états métastables et hors d'équilibre des électrolytes aqueux LiCl, RD2O et BeCl2, RD2O par une caractérisation structurale“. Lyon 1, 1989. http://www.theses.fr/1989LYO10029.
Der volle Inhalt der QuelleBerthelard, Romain. „Viscosité, auto-diffusion et leur découplage dans des solutions aqueuses de glycérol ainsi que dans l’eau pure surfondue sous pression“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1182.
Der volle Inhalt der QuelleWater is the most common liquid for us, but a great deal of its properties are still not well understood. Water exhibits numerous anomalies compared to other liquids and they are enhanced in the supercooled state, that when water is still liquid below the meltin point.During this word, glycerol is added to water (between 10% to 50% in mass) to lower the melting point and the homogeneous nucleation point. Two properties are measured : viscosity and self-diffusion. The first is a macroscopic property related to flow resistance. The second is linked to relative motion of molecules in the liquid. Viscosity and self-diffusion are linked by the Stokes-Einstein equation (SER) at usuals temperature and pressure in liquid. The viscosity of water-glycerol solution is measured by Differentiel Dynamic Microscopy. Diffusion coefficient of colloids in the solution is measured and allows us to deduce viscosity of the solution. Viscosity raises as temperature raises. At given temperature, viscosity raises in respect with glycerol’s concentration. Viscosity’s behavior according to temperature depends on the concentration. At low concentration (< 20%) it behaves the same way as pure water. For higher concentrations, other laws are more suitable to describe viscosity. Henceforth, adding glycerol modifies supercooled solutions’ dynamic. Mutual diffusion of molecules is related to their mobility. It is characterized by self-diffusion in a pure liquid and intra-diffusion in mixtures. Intra-diffusion in glycerol solutions are measured with concentration ranging from 1% to 50% in mass thanks to NMR-PGSE. Water and glycerol diffusions raise with temperature, whatever the concentration. At high temperature, diffusion decreases as concentration raises. At low temperature and low concentration (1% in glycerol), glycerol’s diffusion decreases more rapidly than for other concentration as temperature is lowered. Water seems to have the same tendancy in similar conditions. Knowing viscosity and intra-diffusion, it is possible to get SER’s evolution according to temperature. The SER is always violated for water molecules as soon as temperature is lower than 273 K. Glycerol molecules behave the same way when their concentration is 30% and 50%. For 10%, the SER is unexpectedly observed. At 1% the SER is violated again, but in opposite way compared to what is usually observed. Microscopic interpretation of these observations remains elusive. We also performed viscosity and self-diffusion measurements on pure water under pressure up to 150 MPa. SER is also tested for temperatures down to 228 K, allowing comparison with recent numerical simulations
Laurent, Oscar. „Ions et gaz dans les verres de silice : étude dynamique et approches topologiques“. Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066243/document.
Der volle Inhalt der QuelleRigidity theory allows to predict the behavior of many properties of glasses with respect to composition, while considering the underlying network as simple mechanical trusses that can be flexible, isostatic or stressed-rigid. Some recent works showed how useful such an analysis can be, either theoretically or experimentally. In the thesis we will use a method to analyse topological constraints from molecular dynamics simulations in order to establish the rigidity of silica systems of interest under various conditions of composition, pressure and temperature. Applying this constraints counting algorithm to radial and angular constraints in soda-lime systems allowed us to establish composition intervals of isostatic properties while giving a novel comprehension of the constraints and the structure surrounding the ions. We later highlight the faint influence of noble gases atoms upon silica when melted in the bulk. That study also allowed us to link dynamical anomalies of silica under pressure to rigidity changes of the network
Busselez, Rémi. „Propriétés de fluides vitrifiables bio protecteurs nanoconfinés“. Rennes 1, 2008. http://www.theses.fr/2008REN1S057.
Der volle Inhalt der QuelleIt was shown that confinement on a nanometric scale considerably modifies the structure, the thermodynamical and dynamical properties of simple molecular liquids. A large number of studies devoted to pure molecular glass formers in restricted geometries have revealed a complex entanglement of low dimensionality, finite size and surface effects. The current understanding of the dynamics of interfacial or confined liquids must be extended to more complex fluids, in order to be relevant to different domains of technological or biological interest. One of these concerns biopreservation. Indeed, a new level of complexity is awaited for confined bioprotectant solutions, which are multi-component systems with strong and selective H-bond interactions. We have performed a structural and dynamical investigation of the archetype glycerol-trehalose bioprotectant solution confined in silicon unidirectional nanopores. Neutron scattering and solid state NMR experiments have been combined to molecular dynamic simulations. They unambiguously reveal antagonist effects of trehalose concentration and nanoconfinement on the structure and molecular dynamics from the nanosecond time scale to the glassy arrest
Lerbinger, Matthias. „Réarrangements locaux dans les verres modèles : de la micromécanique aux processus de relaxation dans un liquide surfondu“. Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS006.
Der volle Inhalt der QuelleIn this thesis, the local yield stress method is applied and extended to study single, irreversible atomistic rearrangementsas well as structural relaxation in a model glass-forming liquid, a two dimensional binary Lennard-Jones mixture. Themethod gives access to the local mechanical response of an inherent configuration in a direct and non-perturbativemanner while controlling the length scales and loading directions. In the first part, the focus is on a small inclusion ofthe glass. Its micromechanical response is probed in the athermal quasi-static limit. The influence of the length scale,at which the mechanical response is probed, is discussed. The variation of the threshold statistics with the size of theprobing zone can be understood on the basis of a simple geometric argument and a weakest link assumption. Then, upondetermining the dependence of the local critical yield stress on the shear loading direction with a high angular resolution,it is observed that only a finite and discrete number of shear rearrangements is accessible, each of them having a distinctweak plane. Furthermore, the critical yield stress shows a high sensitivity towards the pressure in the simulation box. It isfound that for the length scale studied, a Mohr-Coulomb yield criterion describes piecewise accurately the critical shearstress. In the second part, a connection between structure and dynamics of model supercooled liquids is established. Thenovelty in the present work is the characterization of the structure through local slip thresholds. A strong correlation isfound between the stress barriers in the softest direction calculated in the as-quenched state and observables associatedto the relaxation of the liquid structure at parent temperature. As expected, a higher correlation coefficient is detected forliquids equilibrated at lower temperatures, as the potential energy landscape increasingly influences the dynamics
Kotbi, Mohammed. „Etude structurale d'une solution aqueuse de chlorure de lithium LiCl, 6H2O par la méthode de Monte Carlo inverse (RMC)“. Lyon 1, 1999. http://www.theses.fr/1999LYO10105.
Der volle Inhalt der QuelleVest, Julien-Piera. „Dynamique vitreuse sur la sphère S2“. Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066670/document.
Der volle Inhalt der QuelleWe are interested in the description of the dynamics of a supercooled liquid through the study of a model which relies on a simple geometrical ingredient. Starting from a monodisperse Lennard-Jones system on the euclidean plane, we add frustration by curving the space to form a sphere of arbitrary radius. Using a molecular dynamics algorithm, we showed that this system indeed behaves like a glassy liquid at equilibrium. The dynamics, caracterized by the self-intermediate scattering function $F_s(k,t)$, slows down strongly and changes shape at low temperature, for a small variation of the statics. The system behaves like a strong glass for high curvatures, but its fragility increases when the curvature decreases. The shape of $F_s(k,t)$ is also modified when the curvature decreases, which we tried to explain theoretically through the study of the mode coupling theory (MCT) on the sphere. We derived the dynamical equation of spherical MCT and studied the long time limit of its solution. We predict a dynamic transition similar to the one predicted by euclidean MCT, which does not allow us to explain the effect of curvature on $F_s(k,t)$, though the curvature has an influence on the value of the transition temperature. Finally, we studied the role of "defects", among which a minimal number of $12$ is imposed by topology. At low temperature, the defects tend to form linear structures, as predicted theoretically and observed in some experiments. The defects have a strong contribution in the relaxation; however, the role of other particles is not negligible
Rulquin, Charlotte. „Rôle des fluctuations dans les systèmes vitreux de dimension finie“. Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066454/document.
Der volle Inhalt der QuelleWhen the temperature diminishes, glassy systems present a very sluggish dynamics and at low enough temperature can finish in some arrested disordered state. This thesis deals about the case of structural glasses, to which category supercooled liquids belong to, and spin glasses.In these two cases the physical scenarios issued from the mean-field theories are known and could be fragile to the introduction of fluctuations that are present in finite-dimensional systems. Since the study of the effect of fluctuations in glassy systems is a daunting task, the aim of this thesis is to study simple related problems in which the effect of fluctuations can be thoroughly investigated.For the structural-glass case, we study first the return to convexity of the free energy of a uni-dimensional finite-size system where fluctuations are restricted by the finite size of the system. Then, we study the role of "short"- and "long"-range fluctuations in a glass-former model called ``plaquette model'' in comparing the thermodynamic properties of the system which are known on Euclidean lattices with the ones we obtained on a "tree" lattice. Finally, we study the existence of space-time fluctuations in a model made of activated-dynamics systems coupled via a thermal bath at low temperature.For the spin-glass case, we construct a scheme for the nonperturbative renormalization group to describe the effect of critical fluctuations on the critical properties of the Ising spin glass in zero field in dimensions lower than six
Krakoviack, Vincent. „Approches de couplage de modes et de champ moyen de la transition vitreuse : utilisation de modeles schematiques pour l'analyse quantitative de la dynamique des liquides surfondus“. Paris 11, 2000. http://www.theses.fr/2000PA112101.
Der volle Inhalt der QuelleAffouard, Frédéric Descamps Marc. „Étude des mécanismes de la transition vitreuse et de l'action bioprotectrice des sucres“. Villeneuve d'Ascq : Université des sciences et technologies de Lille, 2008. https://iris.univ-lille1.fr/dspace/handle/1908/1142.
Der volle Inhalt der QuelleN° d'ordre (Lille 1) : 551. Articles en anglais reproduits et intégrés au texte. Titre provenant de la page de titre du document numérisé. Bibliogr. p. 61-66 et bibliogr. des articles. Liste des publications et communications.
Rajonson, Gabriel. „Etude et comparaison de moteurs moléculaires artificiels par simulation numérique“. Thesis, Angers, 2019. http://www.theses.fr/2019ANGE0029.
Der volle Inhalt der QuelleThe nanometric field raises a lot of questions. One of them concerns molecular motors. Is it possible to design a device capable of moving itself inside an environment ? If so how can we characterise its motion ? Does it influence the environment ? Does the environment influence the motor’s motion ? We took an interest here to the study of several parameters such as the ratio of the motor’s relative length to the environment’s molecule length, the ratio of the motor’s relative mass to the environment’s molecule mass, the motor’s folding frequency, thetemperature’s influence, the motor’s orientation, the different time configurations. We showed that the motor’s relative length ratio to the environment’s molecule length, as well as the motor’s relative mass ratio to the environment’s molecule mass, have an influence on the motor’s displacement. Every motor presenting one hinge, is subject to the scallop theorem introduced by E.M. Purcell. We found a way to break this theorem by playing on the motor’s folding frequency. Then we altered our motor in order for it to possess to hinges. We studied the effect of different time configuration on the motor’s displacement. Finally we wanted to give a privileged direction to our motor by submitting it to an electrical field
Crauste, Caroline. „Etude expérimentale d'une longueur de corrélation dynamique à la transition vitreuse“. Paris 6, 2009. http://www.theses.fr/2009PA066308.
Der volle Inhalt der QuelleGuillaud, Emmanuel. „Multiscale experimental and numerical study of the structure and the dynamics of water confined in clay minerals“. Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1123/document.
Der volle Inhalt der QuelleClay are complex minerals with a multiscale porosity and a remarkable ability to swell under humid atmosphere. These materials have many applications in catalysis, waste management, construction industry... However, the properties of confined water are still not fully understood, due in particular to the complexity of water itself. The aim of this work is, using mainly molecular simulations and vibrational spectroscopy, to understand the structure and the dynamics of water confined in clay minerals. To evaluate the accuracy of numerical models to describe water confined in clay minerals, and to understand the origin of its structural and dynamical properties, a large part of the work was devoted to the building blocks of clays: pure bulk water, water at the surface of a solid, and salt water. To this extent, the viscoelastic properties of water from the deeply supercooled regime to the boiling temperature were investigated using classical molecular dynamics. The evolution of the friction properties of water on a prototypical solid surface was also analyzed, and the accuracy of ab initio approaches and empirical salt models was studied.In a second part, those results were confronted to the properties of water confined in clay minerals at low and room temperature, studied both experimentally and numerically. Experimental work consisted mostly in extensive far- and -mid infrared absorption spectrometry measurements, whereas numerical work mainly consisted in empirical molecular dynamics simulations. Especially, the existence of confinement- or temperature-induced phase transitions of confined water was investigated
Petitjean, Mélanie. „Interactions des composés organiques volatils avec des surfaces de glace pure ou dopée représentatives des conditions atmosphériques rencontrées dans la moyenne et la haute troposphére : application à la chimie des nuages mixtes et des cirrus“. Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/PETITJEAN_Melanie_2010.pdf.
Der volle Inhalt der QuelleThe upper troposphere (UT) is characterized by its low temperatures, from 188 to 233 K and the presence of cirrus clouds. These clouds, composed of ice crystals, can cover up to 25% of the Earth's surface. Mixed and cirrus clouds may be a potential sink for many gaseous species and can promote heterogeneous or photochemical reactions. In this work, the establishment of the adsorption isotherms on pure or doped ice surfaces between 253 and 203 K, provides quantitative information on the partitioning of organic species between the gas and condensed phases at temperatures encountered at medium altitudes and in the UT. The presence of Oxygenated Volatile Organic Compounds (OVOC) such as alcohols, aldehydes, ketones and carboxylic acids, in the UT is well established. As carbonyl compounds are involved in the formation of photooxidants such as ozone, this work has been focused on the study of these compounds. In addition, other molecules (aromatic hydrocarbons) have been studied to better understand the relationships between the structure of the molecule and its ability to be adsorbed on ice surfaces. Besides, computer simulations have led to some details at the molecular level on the three dimensional structure of the adsorption layer. This work has also allowed the determination of the vapor pressure of both hydroxyacetaldehyde and hydroxyacetone ,providing reference values for future laboratory studies and permitting estimation of their partitioning between the gas and particle atmospheric phases
Crauste-Thibierge, Caroline. „Etude expérimentale d'une longueur de corrélation dynamique à la transition vitreuse“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00552203.
Der volle Inhalt der QuelleBauchy, Mathieu, und Matthieu Micoulaut. „Contraintes topologiques et rigidité dans les verres“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00805762.
Der volle Inhalt der QuelleMarín, Aguilar Susana. „Local structure and dynamics of dense colloidal systems : from patchy particles to hard spheres“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP052.
Der volle Inhalt der QuelleThe role played by the structure in determining the dynamics of glassy colloidal systems is still a subject of debate. However, there is compelling evidence of a direct link between changes in the local structure and the dynamical slowdown in glassy systems. Here, we explore the interplay between local structure and dynamics by using patchy particles as glass formers. This is done by making use of molecular dynamics simulations. We show that reinforcing icosahedral geometry causes, the system to exhibit an extreme slowdown in its dynamics. With these results, we provide a route for controlling glassy dynamics through the use of patchy particles. Additionally, an interesting point is whether we can extract information about dynamics from only structural information. In order to explore this point, we simulate a wide variety of hard-sphere mixtures. We show that global dynamics of these systems can be precisely predicted by quantifying the tetrahedrality of the local structure: an order parameter that consists of counting the number of tetrahedra each particle participates in. The predictions of this order parameter maintain their accuracy over a wide variety of densities proving its universality in this family of glass formers. Moreover, it is also capable of capturing the changes in the local dynamics, as regions with high tetrahedrality are strongly correlated with regions with slow dynamics. Finally, we demonstrate that unsupervised machine learning techniques can be used to classify particles with different structural environments, which are strongly correlated to local dynamics
Albert, Samuel. „Un point critique thermodynamique dans les verres dévoilé par les réponses d'ordre élevé“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS534/document.
Der volle Inhalt der QuelleThe puzzle of the glass transition mainly resides in the fact that a supercooled liquid undergoes when cooled down, a spectacular dynamics slow down, while no evidence of any kind of thermodynamic transition has been measured through usual means.The absence of any known growth of a length scale that could explain the glassy dynamics leads to a wide range of competing models and theories trying to explain the origins of this dynamics.In the last decade, a promising lead has been put forward, that could allow the community to experimentally access such a growing length scale, through third order non-linear dielectric response measurements, and more in particular this response's temperature dependence. Indeed, non-linear response measurements reflect the collective effects that characterize the amorphous order and translate into high order correlation functions.During this PhD, we have built upon this experimental and theoretical background to design a fifth order non-linear dielectric response measurement experiment. In collaboration with a team of experimentalists and theoreticians, we have used these results in conjunction with third order response measurement results to make a very strong case advocating the existence of a thermodynamic critical point in Glycerol and Propylene Carbonate. This is a very significant advance in the understanding of the behaviour of glassy materials.This ground breaking discovery puts very strong constraints on existing theories and will contribute to end some decades-long theoretical debates within the glassy community
Ninarello, Andrea Saverio. „Computer simulations of supercooled liquids near the experimental glass transition“. Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS071/document.
Der volle Inhalt der QuelleUnderstanding the mechanisms that lead to glass formation is one of the open problems for the condensed matter research. Numerous questions remain unanswered, because the tremendous increase of relaxation times during the cooling process prevents the exploration of equilibrium properties of supercooled liquids at very low temperature. Computer simulations of glass-forming liquids are nowadays able to reach equilibrium at temperatures comparable to the Mode-Coupling crossover temperature, which is well above the experimental glass transition temperature. As a consequence, simulations lag eight orders of magnitude behind experiments in terms of equilibration times. Progress to close this gap has been slow, and stems mostly from hardware improvements.In this thesis we make an important step to close this gap. We combine the use of a Monte Carlo algorithm, known as the swap algorithm, with the design of novel glass-forming models. We systematically test numerous models using both discrete mixtures and polydisperse systems. We discuss the role that polydispersity and particle softness play in avoiding crystallization and in efficiently reaching previously unexplored regimes. We study the dynamical processes taking place during swap Monte Carlo simulations. We demonstrate that in some cases our technique is able to produce thermalized configurations at temperatures inaccessible even by experiments.In this newly accessible regime, we investigate some open questions concerning the glass transition. We show that a hard sphere fluid can be equilibrated at, and even beyond, the jamming packing fraction. We measure the configurational entropy in extremely supercooled liquid, finding a strong dimensional dependence that supports, on the one hand, the existence of an ideal glass transition at a finite temperature in three dimensions and, on the other hand, its absence in two dimensions. We detect the increase of amorphous order quantified through a static point-to-set length throughout the glass formation. We measure the critical exponents introduced in the mean-field theory of glasses much closer to the supposed ideal glass transition. Finally, we reveal the absence of a sharp geometric transition in the potential energy landscape across the Mode-Coupling crossover.The models and the algorithms developed in this thesis shift the computational studies of glass-forming liquids to an entirely new territory, which should help to close the gap between theory and experiments, and get us closer to solve the long-standing problem of the glass transition
Berthier, Ludovic. „Dynamique forcée des systèmes vitreux : des verres de spin aux fluides complexes“. Phd thesis, Université Claude Bernard - Lyon I, 2001. http://tel.archives-ouvertes.fr/tel-00001364.
Der volle Inhalt der QuelleZouzou, Nichet Alexandre. „Modélisation de la congélation d'un film fluide soumis à une précipitation surfondue“. Thèse, 1996. http://constellation.uqac.ca/1139/1/1529119.pdf.
Der volle Inhalt der QuelleBeaucage, Philippe. „Processus de nucléation et de cristallisation du silicium liquide à l'aide du potentiel de Stillinger-Weber“. Thèse, 2004. http://hdl.handle.net/1866/14762.
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