Dissertationen zum Thema „Surface ouverte“
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Bahrim, Bogdana Mioara. „Transfert de charge dans les collisions atome-surface métallique : application aux systèmes à couche ouverte“. Paris 11, 1996. http://www.theses.fr/1996PA112236.
Der volle Inhalt der QuelleLaroussi, Myriam. „Modélisation du comportement des mousses solides à porosité ouverte : une approche micromécanique“. Phd thesis, Ecole des Ponts ParisTech, 2002. http://tel.archives-ouvertes.fr/tel-00005743.
Der volle Inhalt der QuelleCe travail est dédié à létude de lorigine de la phase de plateau dans le cas des mousses élastiques à porosité ouverte. Celle-ci est attribuée au flambement élastique des arêtes des cellules. Létude repose sur la théorie de lhomogénéisation non convexe. En effet, on modélise la mousse par une microstructure tridimensionnelle périodique en prenant en compte les non-linéarités géométriques.
Dans un premier abord, on étudie deux cas de chargement en grandes transformations : une compression uniaxiale et une déformation uniaxiale (ou compression oedométrique). Les calculs sont faits sur des cellules détude de plus en plus grandes. Dans le cas de cellules détude pas « suffisamment grandes », on introduit une imperfection dans la position des nuds pour initier le flambement.
Ensuite, on applique des chargements multiaxiaux pour déterminer une surface de charge dans lespace des contraintes, marquant la limite de passage de la phase élastique initiale à la phase de plateau. La surface de charge, dite micro, est obtenue en considérant des variations du déplacement périodiques sur des cellules détude de plus ne plus grandes. Cest une surface de charge du type Drucker-Prager modifiée. On introduit également une nouvelle surface de charge, dite mixte, plus aisée à calculer et qui coïncide avec la surface micro dans le cas étudié.
Enfin, pour valider les résultats numériques, on réalise une étude expérimentale sur une mousse de caril.
Dari, Carolina. „New innovative methods for cleaning surfaces using foams based on bio-based surfactants“. Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILR038.
Der volle Inhalt der QuelleIn the food industry, surfaces contaminated with microorganisms are a major cause of cross-contamination, resulting in foodborne illness and food waste. Despite thorough cleaning efforts, foodborne illness rates are rising, suggesting current practices are insufficient. Traditional cleaning methods also consume large amounts of water, energy, and chemicals, raising sustainability and environmental concerns. The industry is exploring more sustainable alternatives, such as dry-cleaning methods, eco-friendly products, and advanced control systems, to reduce resource consumption while maintaining hygiene standards. One promising alternative for cleaning closed surfaces is the use of foam, a method already used for open surfaces. Foam cleaning can potentiallyreduce water, energy, and chemical consumption. The aim of this thesis is to study the links between foam properties and removal of microorganisms from both open and closed surfaces, and explores innovative cleaning techniques to develop more sustainable and efficient methods for the food industry.The first part is dedicated to the cleaning of open surfaces, i.e., static foam cleaning. Here we study the removal of hydrophilic and hydrophobic Bacillus subtilis spores from stainless steel surfaces by using foams. The model foams are formulated with bio-based surfactants (10-hydroxystearic acid and sodium cocoyl isethionate). The relationship between bubbles size and foam liquid fraction and the decontamination efficiency is investigated to determine the mechanisms of foam action. Foams themselves can decontaminate surface soiled with spores, most probably by wiping and imbibition mechanisms. Foams with smaller bubbles size have the highestdecontamination efficiency. Under the conditions studied, the liquid fraction is not the main parameter governing the decontamination efficiency.The second part is dedicated to the cleaning of closed surfaces, i.e., foam flow cleaning. Here we study the efficiency of foam flow formulated with a model surfactant (Sodium dodecyl sulfate) in comparison with foam flow formulated with bio-based surfactants (alkyl polyglucosides) to remove hydrophilic spores from pipes. We demonstrate similar efficiency for short cleaning times). In addition, through a life cycle assessment we demonstrate the reduction of several environmental impacts with the use of bio-based surfactant compared to the model surfactant.The third part is dedicated to the stabilization of water-in-water emulsions and the production of a foamulsion based ont these emulsions. We study the stabilization of PEG-in-Dextran emulsions with lamellar gel networks based on alkyl polyglucosides and fatty alcohols. We show that highly stable emulsions are obtained over a long period of time for specific formulation conditions. We also demonstrate for the first time the production of a foamulsion based on water-in-water emulsions
Biquard, Olivier. „Fibrés holomorphes et connexions singulières sur une courbe ouverte“. Palaiseau, Ecole polytechnique, 1991. http://www.theses.fr/1991EPXX0021.
Der volle Inhalt der QuelleMezouari, Abderrahmane. „Etude d'un resonateur electromagnetique ouvert a ondes de surface“. Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2S882.
Der volle Inhalt der QuelleMezouari, Abderrahmane. „Etude d'un résonateur électromagnétique ouvert à ondes de surface“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37607990b.
Der volle Inhalt der QuelleMéheust, Yves. „Écoulements dans les Fractures Ouvertes“. Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00008477.
Der volle Inhalt der QuelleBeudaert, Xavier. „Commande numérique ouverte : interpolation optimisée pour l'usinage 5 axes grande vitesse des surfaces complexes“. Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2013. http://tel.archives-ouvertes.fr/tel-00918816.
Der volle Inhalt der QuelleBammou, Lahcen. „Instabilité thermoconvective d'un écoulement Poiseuille-Rayleigh-Bénard-Marangoni en canal ouvert à surface libre“. Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3030/document.
Der volle Inhalt der QuelleSeveral studies both numerical and experimental have reported the presence of thermal instabilities in liquid films uniformly heated from below for specific boundary conditions and flows. The presence of these instabilities modifies the associated heat transfer. The subject of this PhD thesis is to study numerically the instability of three-dimensional laminar mixed convection within a liquid flowing on a horizontal channel heated uniformly from below. The upper surface is free and assumed to be flat. The variations of the surface tension with the temperature (Marangoni effect or thermocapillary effect) are taken into account. Although of great interest for many industrial applications, this problem has received little attention from an academic point of view. In this configuration, several types of thermoconvective structures may appear. When the strength of the buoyancy, thermocapillary effects and forced convective currents are comparable, the results show the development of instabilities in the form of steady longitudinal convective rolls similar to those encountered in the Poiseuille-Rayleigh-Bénard flow. To our knowledge, this is the first time that the Poiseuille-Rayleigh-Bénard flow associated to the Marangoni effects has been investigated. The number and spatial distribution of the convective rolls along the channel depend on the flow conditions. We propose a numerical study on the flow conditions that could lead to thermal instabilities with an evaluation of their effect on the heat transfer. The coupled Navier-Stokes and energy equations are solved numerically by the finite volume method taking into account the thermocapillary effects. The results presented concern the influence of several control parameters (the Reynolds, Rayleigh, Biot and Marangoni numbers and the aspect ratio of the channel) on the flow patterns and heat transfer characteristics. In the second part of this work, complimentary to the first, a linear stability analysis of a horizontal liquid film flowing in an open channel, with infinite lateral extension and uniform heating from below, is carried out. An eigenvalue problem is obtained in the course of this analysis which is solved numerically using the Chebyshev collocation spectral method. The stability diagrams determining the threshold parameters leading to thermoconvective instabilities were obtained and analyzed as well as the associated spatial patterns
Danilo, Céline. „Évaluation des courants de surface océanique au moyen d'un radar à ouverture synthétique“. Phd thesis, Université de Bretagne occidentale - Brest, 2009. http://tel.archives-ouvertes.fr/tel-00560597.
Der volle Inhalt der QuelleDanilo, Céline. „Évaluation des courants de surface océanique au moyen d’un radar à ouverture synthétique“. Brest, 2009. http://www.theses.fr/2009BRES2023.
Der volle Inhalt der QuelleThe aim of this thesis is to extract the radar line-of-sight component of sea surface current from the Doppler shift of a signal received by a synthetic aperture radar on board of ENVISAT. The primary goals of this work are the separation of waves and surface current components to this Doppler shift and, furthermore, the expansion of this analysis to multiple angles of incidence, thereby making it possible to map sea surface currents. This study is limited to vertical polarization and to the radar frequency hand C. Extraction of current signature is based on the assumption that the Doppler shift is caused solely by surface gravity waves and by surface current. Moreover, we initially assume that the current is uniform within the surface of Doppler shift estimation. Under these assumptions, the current component can be deduced from the Doppler shift by substracting the wave component. The latter have relatively short wavelengths, which is typical of wind-sea. Practical use of 10 m wind information for the estimation of waves component is evaluated. A method for extracting surface current information is developed and tested, initially for a constant incidence angle of 23°, on small-sized and isolated ocean images from all over the oceans. A comparison of the monthly average speeds, obtained by on-site current measurements, indicates an RMS error of 0. 35 m/s. As a further step, the same methodology is applied for larger acquisitions (400 km by 400 km minimum) for which the incidence angle ranges from 16 to 42°, This new configuration requires a preliminary analysis of the effect of incidence angle variation on the Doppler shift. We show that an increase of the angle of incidence results in the increase of the relative component of surface current to the Doppler shift, and that the latter also varies according to the direction of wind with respect to the direction of the radar. The estimated surface current component shows a good quantitative correspondence with the same component measured by on-site sensors. This result is encouraging in view of the development of a more systematic technique. Finally, the last part of this work is devoted to a more complex case, namely that of coastal current: here, the hypothesis of a uniform surface current within the estimation surface cannot be maintained anymore due to the great variability of these currents. In this case, we proceed by analyzing maps of Doppler shift of a 1 km resolution. Despite the complexity of this situation, once again, the comparison between Doppler shift-derived velocities and data from tidal current maps indicates a strong potential of SAR images to return high resolution information on surface currents
Marty, Florian. „Des ouverts Zariski et des morphismes lisses en géométrie relative“. Toulouse 3, 2009. http://thesesups.ups-tlse.fr/540/.
Der volle Inhalt der QuelleIn this thesis, the author work on the relative scheme theory defined by B. Toën and M. Vaquié in the article "Au dessous de Spec(Z)". More precisely, he studies the properties of Zariski open immersions and smooth morphisms in a relative context, not necessarily additive. The first issue is a description in terms of prime ideals of the Zariski topological space associated to a relative affine scheme. The second issue is a definition of a notion of relative smooth morphism, between monoids, which recover the notion of smooth morphism between rings. The author proves in particular that the affine line is smooth in most relative contexts, as for example the context of scheme over the field with one element (* -> N is smooth) or the context of N-schemes (N ->N[X] is smooth)
Zemmour, Samira. „Nouvelle génération de colonnes capillaires ouvertes de dimension micronique pour l’analyse protéomique basées sur la fonctionnalisation de surface“. Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10028.
Der volle Inhalt der QuelleThe miniaturization of separative systems is continuously developing today. This emergence is due to the very low sample volume and the increasing need to save analysis time. The present thesis comprises two parts. The first one consists on developing a new generation of open capillary columns ("open tubular") based on micron-scale surface functionalization and characterization of their properties in proteomics analysis for the separation of peptide digests by reversed-phase liquid chromatography. The surface functionalization was carried out after activating silica capillary wall by grafting silylated derivatives including glycidyl methacrylate. The epoxide function was then broken by aliphatic primary amines to increase the hydrophobicity of the stationary phase. This two-step strategy has the advantage of allowing a split grafting of the functional unit and a wider variety of functionalizations. These columns were tested on standard peptides or peptide digests with analysis by MALDI-TOF offline and online nanoLC nanoESI-coupled ion trap. The effects of various parameters, particularly the length of the alkyl chain, on the retention of peptides were studied. The obtained results show that by decreasing the length of the amine carbon chain, peptides are eluted at a lower percentage of acetonitrile. In fact the shortening of the carbon chain results in the decrease of hydrophobic interactions and in faster peptides elution.The second part of this thesis presents preliminary developments of polymer grafting of type MIP (Molecular Imprinted Polymers) for the separation of peptides and proteins. The synthesis of molecularly imprinted phase is made from a mixture of monomers having acid or basic functions and imprint molecules that interact during the polymerization by non-covalent bonds. Once the polymerization is complete, the imprint molecules are removed from the polymer matrix, which results in the formation of a rigid polymer containing recognition sites that are specific to the model molecules. The molecularly imprinted columns were designed to selectively retain the target molecules or molecules similar in size and in structure, within a complex mixture by specific interactions. Affinity between two different peptides was obtained with good selectivity. Preparation of MIP and NIP (No Imprinted Polymers) columns was performed to compare the retention capacity of both materials and to verify the selectivity of the MIP uptake compared to NIP with respect to the target molecule. These columns were also tested by mass spectrometry MALDI-TOF
Denoyer, Alexandre. „Rôle des chimiokines CXCL12 et CX3CL1 dans la physiopathologie du trabéculum et de la surface oculaire au cours du glaucome“. Paris 6, 2011. http://www.theses.fr/2011PA066079.
Der volle Inhalt der QuelleGlaucoma is the first cause of irreversible blindness in the world. Primary open-angle glaucoma (POAG) mostly combines retinal neuropathy with abnormal elevation of the intraocualar pressure, which is the first risk factor for the disease. Ocular hypertension is caused by a trabecular meshwork degeneration whose primary mecanisms are still unknown. Indeed, the current antiglaucoma treatment does not target the intial trabecular pathology so it is not currative. Moreover, antiglaucoma eye drops often contain a preservative, such as benzalkonium chloride (BAC), which has been demonstrated to cause ocular surface inflammation in glaucomatous patients treated over a long term period. Chemokines, small proteins from the cytokine family, have been first described for their chemotactic properties for leukocytes through their interaction with G protein coupled receptors. Aside from its immune properties, the chemokine CXCL12 is involved in the regulation of cell viability and extracellulare matrix remodelling through its receptor CXCR4. Recently, it has been reported that proteolytic cleavage of CXCL12 yields a proapoptotic form, SDF-1(5-67), acting via another chemokine receptor :CXCR3. In this thesis, CXCL12, CXCR3 and CXCR4 have been detected in trabecular cells in human glaucomatous trabecular tissue and immortalized cell line. We originally describe a balance between the protective system CXCL12/CXCR4 and SDF-1(5-67)/CXCR3 which induces trabecular apoptosis under the control of cytokines and matrix metalloproteinases known to be involved in POAG. We report the sucessful use in vivo of a non-peptide specific antagonist of CXCR3 in reducing ocular hypertension and restoring trabecular function in an animal model of glaucoma, opening up new therapeutic avenues in glaucoma. We also studied the role of another chamokine, CX3CL1, in the ocular surface inflammation induced by BAC. CX3CL1 is charaterized by powerful chemoattract properties on CX3CR1-bearing leukocytes. In this study, we report an overexpression of CX3CL1 in conjunctival epithelial cells in glaucomatous patients treated with a BAC-containing medication. In vitro, we demonstrate that BAC-stimulated conjunctival epithelial cells attract lymphocytic and monocytic subpopulations by producing CX3CL1. In an animal model of BAC-induced ocular toxicity, we report a decrease in macrophage infiltration to the conjunctiva in CX3CR1-deficient mice compared to wild-type animals, further confirming that CX3CL1/CX3CR1 is involved in immune cell trafincking in the ocular surface. Our results originally show that chemokines are involved in the pathophysiology of the anterior segment in glaucoma. Chemokines appear as a new regulating system for the pathogenesis of trabecular degeneration in glaucoma as well as for ocular surface inflammation, and could constitute new specific therapeutic targets in such deleterious diseases
Baillis, Dominique. „Modelisation des transferts thermiques dans des materiaux semi-transparents de type mousse a pores ouverts et prediction des proprietes radiatives“. Lyon, INSA, 1995. http://www.theses.fr/1995ISAL0010.
Der volle Inhalt der QuelleCoupled heat transfer by radiation and conduction in open cells insulation is modelized from the material morphology and the two phases : solid and gas, properties. A simple cubic model is used to predict the conductivity in these materials. The spectral volumetric absorption and scattering coefficients and the spectral phase function were predicted from the dimensional and hemispherical reflectivity of particles which constitute solid structure by applying to thee particles a combination of geometric optics law and of diffraction theory, these properties are then utilized in a coupled conduction-radiation model. The discrete ordinate method or the Rosseland model used with a weighted extinction coefficient were successively adopted to solve the radiative heat transfer equations. The carbon reflectivity contained in these materials is determined by an identification method (Gauss method of linearization) applied to bidirectional spectral transmittance data obtained from an experimental device using a Fourier transform infrared spectrometer. Moreover experiences on a device of graded hot plate-type have permitted to compare results of experimental and theoretical total conductivity thus contributing to the validation of the realized modeling
Mariot, David. „Nouveau procédé de modification de silice pour le renforcement d'élastomères silicones“. Thesis, Montpellier, Ecole nationale supérieure de chimie, 2011. http://www.theses.fr/2011ENCM0013.
Der volle Inhalt der QuelleThis work deals with a new way of modifying silica surface in a view to reinforce silicone elastomers. The surface-initiated ring-opening-polymerization (Si-ROP) of cyclosiloxanes was performed directly from the surface of silica dispersed in water. The characteristics of silica used in this study and their behavior in aqueous dispersion were first studied. For pH higher than the Point of Zero Charge, silica presents silanolate groups at its surface that are able to initiate the ROP of cyclosiloxanes from the surface, and not in aqueous suspension. The influence of the counter-cation and its concentration proved to be essential, in addition to silica's adsorbing properties. Modified silicas obtained by this new process were deeply analyzed by thermogravimetric analyses (TGA), fragmentation-GC, simple impulsion 29Si RMN and pyrolysis GC-MS in order to describe precisely the grafting conformation. The polymerization process was then scaled up to produce higher quantities of modified silica, which were incorporated in a model silicone formulation. Highest and lowest grafting densities tended to poor silica dispersions, as shown by image treatment. Hardness tests, uniaxial tensile and cyclic tests and tear resistance tests were performed in order to evaluate the influence of the grafting (conformation and vinylated groups) on silicone elastomers properties
Monjarret, Ronan. „The multi-layer shallow water model with free surface : treatment of the open boundaries“. Toulouse 3, 2014. http://www.theses.fr/2014TOU30334.
Der volle Inhalt der QuelleMarouani, Nesrine. „Facteurs affectant la formation de biofilm et la persistance d'Escherichia coli O157 :H7 sur les surfaces ouvertes des ateliers de transformation de viande“. Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0076.
Der volle Inhalt der QuelleJeger-Madiot, Nathan. „Conception d'un imageur ultrasonore dans l'air pour la mesure des ondes basses-fréquences en surface du corps humain“. Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066330/document.
Der volle Inhalt der QuelleThe aim of the work presented in this dissertation is to develop an airborne ultrasonic system for the contactless measurement of vibrations on the human body surface. The vibration study of the skin surface opens several application fields. The visualization of the surface wave velocity on the skin from the propagation movie allows to characterize the superficial layer elasticity as well as its heterogeneities. From this analysis, objects hidden on or under the skin can be detected for a security purpose. A second application is the observation of the surface vibrations generated by the heartbeat, respiration and pulse wave.The implementation of a first single-channel device allowed the local measurement of vibrations about ten microns order. From this initial work, we developed a 2D airborne ultrasonic imager with high frame rate. It is composed by a 256 microphones square array and by 12 piezoelectric transducers. The main innovation of our approach is the specular surface imaging. Indeed, the skin roughness is negligible compared to the working wavelength, of the centimeter order to limit the air attenuation. To resolve this issue, the imaging process is carried out with an emission/reception beamforming using synthetic aperture and achieved by a sequential emission of spherical waves.After the system characterization, we imaged the surface wave propagation on a phantom mimicking the human body and the interference between this wave and a foreign object. A second version of the 2D imager, composed by 36 emitters, was applied to measure the deformation of the thorax during the heartbeat as well as the pulse wave propagation in the carotid artery
Tanays, Eric. „Approche algorithmique des conceptions geometriques et geotechniques de mines a ciel ouvert : application a la mine de carmaux (u.e. tarn, h.b.c.m., cdf)“. Paris, ENMP, 1989. http://www.theses.fr/1989ENMP0142.
Der volle Inhalt der QuelleH'Dhili, Fekhra. „Microscopie optique en champ proche utilisant une sonde diffusante : étude de singularités électromagnétiques sur surfaces photosensibles : application à la nanophotolithographie“. Troyes, 2002. http://www.theses.fr/2002TROY0009.
Der volle Inhalt der QuelleThe present thesis work deals with the interaction of the incident light with the apertureless SNOM probe extremity. In appropriate illumination conditions, a local electromagnetic field enhancement can be occurred in the vicinity of the tip end. This phenomenon, known as optical tip effect, generates a high spatially confined light source at the tip apex. An original experimental approach is reported to display directly in near-field this tip effect and to allow a full parametric study of such phenomenon. A numerical simulation of this latter has also been performed and compared to the obtained experimental results. This study allows us at last to optimize the suitable conditions to excite the optical nanosource and to introduce an optical lithography protocol with a nanometric resolution
Mavrocordatos, Constantin. „Étude et réalisation d'un calculateur temps réel pour un radar à synthèse d'ouverture aéroporté“. Toulouse, ENSAE, 1990. http://www.theses.fr/1990ESAE0011.
Der volle Inhalt der QuelleRamaciotti, Morales Pedro. „Theoretical and numerical aspects of wave propagation phenomena in complex domains and applications to remote sensing“. Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX063/document.
Der volle Inhalt der QuelleThis thesis is about some boundary integral operators defined on the unit disk in a three-dimensional spaces, their relation with the exterior Laplace and Helmholtz problems, and their application to the preconditioning of the systems arising when solving these problems using the boundary element method.We begin by describing the so-called integral method for the solution of the exterior Laplace and Helmholtz problems defined on the exterior of objects with Lipschitz-regular boundaries, or on the exterior of open two-dimensional surfaces in a three-dimensional space. We describe the integral formulation for the Laplace and Helmholtz problem in these cases, their numerical implementation using the boundary element method, and we discuss its advantages and challenges: its computational complexity (both algorithmic and memory complexity) and the inherent ill-conditioning of the associated linear systems.In the second part we show an optimal preconditioning technique (independent of the chosen discretization) based on operator preconditioning. We show that this technique is easily applicable in the case of problems defined on the exterior of objects with Lipschitz-regular boundary surfaces, but that its application fails for problems defined on the exterior of open surfaces in three-dimensional spaces. We show that the boundary integral operators associated with the resolution of the Dirichlet and Neumann problems defined on the exterior of open surfaces have inverse operators, and that these operators would provide optimal preconditioners, but that they are not easily obtainable. Then we show a technique to explicitly obtain such inverse operators for the particular case when the open surface is the unit disk in a three-dimensional space. Their explicit inverse operators will be given, however, in the form of series, and will not be immediately applicable in the use of boundary element methods.In the third part we show how some modifications to these inverse operators allow us to obtain variational explicit and closed form expressions, no longer expressed as series, but also conserve nonetheless some characteristics that are relevant for their preconditioning effect. These explicit and closed forms expressions are applicable in boundary element methods. We obtain precise variational expressions for them and propose numerical schemes to compute the integrals needed for their use with boundary elements. The proposed numerical methods are tested using identities available within the developed theory and then used to build preconditioning matrices. Their performance as preconditioners for linear systems is tested for the case of the Laplace and Helmholtz problems for the unit disk. Finally, we propose an extension of this method that allows for the treatment of cases of open surfaces other that the disk. We exemplify and study this extension in its use on a square-shaped and an L-shaped surface screen in a three-dimensional space
Hérault, Nelly. „Préparation contrôlée de catalyseurs bimétalliques Pt-Rh supportés“. Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2298/document.
Der volle Inhalt der QuellePt-Rh supported catalysts have demonstrated interesting properties in selective ring opening of naphthenic molecules. Their catalytic performances depend on several properties like platinum-rhodium interaction. The aim of this work was to study the influence of the preparation method on Pt-Rh interactions. For this purpose, several preparation ways were selected, from the most classical ones, such as impregnation, to more sophisticated ways such as (1) surface modification of monometallic catalyst by addition of a second metal (surface reactions), (2) formation of Pt-Rh particles in microemulsion or in microsuspension, or (3) impregnation assisted by radiolysis. Catalysts were characterized by various techniques such as hydrogen chemisorption, transmission electron microscopy, temperature programmed reduction, adsorption of probe molecules (CO or NO then CO) followed by infrared spectroscopy, or model reactions.These characterizations allowed demonstrating that (i) the classical impregnation or the one assisted by radiolysis leads to monometallic and bimetallic particles, (ii) metal deposition on specific sites of preformed metallic particles can be obtained by surface modification of monometallic catalysts, (iii) the synthesis of metallic particles in microemulsion or microsuspension yields bimetallic entities with Pt-Rh alloy at the particle surface
Mohamed, Ali Debyaoui. „Contribution à la modélisation mathématique et numérique pour des modèles d'écoulement non-linéaires dispersifs en eaux peu profondes“. Electronic Thesis or Diss., Toulon, 2020. http://www.theses.fr/2020TOUL0002.
Der volle Inhalt der QuelleThis work focuses on the modeling and mathematical analysis of asymptotic models used in oceanography describing long wave propagation.This thesis aims to derive and justify new asymptotic models taking into account the variation in topography and cross-section.To do so, several hypotheses are formulated on water depth and cross-sectional deformations. The first part of this thesis is to put the problem into equations, and to find asymptotic models and study them mathematically, see the linear analysis of dispersion and shoaling.In the second part, a one-dimensional model of section-averaged long waves is developed. Three-dimensional equations of motion of non-viscous and incompressible fluids are first integrated over a cross-section of the channel, resulting in the SGN-type equations. Therefore, the new model is adequate to describe fully non-linear and weakly dispersive waves along a channel of an arbitrary and non-uniform cross-section. Specifically, the new model extends the Saint-Venant model to cross-section mean and generalizes the Serre-Green-Naghdi equations to any cross-section.This new model has been reformulated in a way more appropriate for numerical resolution by maintaining the same order of accuracy as the original and improving its propertiesof dispersion. Finally, we present some numerical simulations to study the influence of the change of section on the propagation of a solitary wave.The last part of this thesis is devoted to the numerical simulation of the SGN model with a new reformulation
Oudompheng, Benoit. „Localisation et contribution de sources acoustiques de navire au passage par traitement d’antenne réduite“. Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT071/document.
Der volle Inhalt der QuelleSince the surface ship radiated noise is the main contribution to the underwater acoustic noise in coastal waters, The Marine Framework Strategy Directive of the European Commission recommends the development of the monitoring and the reduction of the impact of the traffic noise. The need for developing an industrial system for the noise mapping of the surface ship have motivated this study, it will allow the naval industries to identify which part of the ship radiates the stronger noise level.In this context, this research work deals with the development of passive noise mapping methods of a surface ship passing-by above a static linear array with a reduced number of hydrophones. Two aspects of the noise mapping are considered: the localization of acoustic sources and the identification of the relative contribution of each source to the ship acoustic signature.First, a bibliographical study concerning the acoustic radiation of a passing-by surface ship is conducted in order to list the main acoustic sources and then to simulate representative ship sources. The acoustic propagation is simulated according to the ray theory and takes the source motion into account. The simulator of the acoustic radiation of a passing-by ship is built in order to validate the proposed noise mapping methods and to design an experimental set-up. A study about the influence of the source motion on the noise mapping methods led to the use of the beamforming method for moving sources for the source localization and a deconvolution method for the identification of the source contribution. The performances of both methods are assessed considering measurement noise and uncertainties about the propagation model in order to know their limitations. A first improvement of the beamforming method consists of a passive synthetic aperture array algorithm which benefits from the relative motion between the ship and the antenna in order to improve the spatial resolution at low frequencies. Then, an algorithm is proposed to acoustically correct the trajectography mismatches of a passing-by surface ship. Finally, the last part of this thesis concerns a pass-by experiment of a towed-ship model in a lake. These measurements allowed us to validate the proposed noise mapping methods and their proposed improvements, in a real and controlled environment
Marchat, Clément. „Caractérisation électrique et optoélectronique de nouveaux matériaux et composants photovoltaïques à partir de techniques AFM“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS094.
Der volle Inhalt der QuelleThis thesis focuses on the characterisation of electrical properties of photovoltaic devices by using two scanning probe techniques: conductive atomic force microscopy (c-AFM) and Kelvin probe force microscopy (KPFM). It starts with a study on crystalline silicon (c-Si), and in particular the influence of surface states on the KPFM measurement. The latter was performed in the dark and under light to extract the surface photovoltage (SPV). This study was completed by numerical simulations that allow to extract surface state densities. A second study was focused on nanowire PV devices. These were PIN radial junctions based on hydrogenated amorphous silicon deposited on highly doped c-Si nanowires. We have shown that on nanowire devices that are covered with ITO,SPV measurements could mirror the value of open-circuit voltage (Voc), while the same measurements performed on single nanowires without ITO top coverage are strongly affected by the shadowing of the AFM tip and by the surface states of the amorphous silicon layer. Finally, we were interested in passivating contacts for c-Si solar cells and analysed poly-Si/SiOx/c-Si structures. When the SiOx interlayer is absent, the KPFM scans exhibit very homogeneous surface potential while numerous areas (with diameter less than 1 micron) of lower surface potential are revealed, when the SiOx buffer layer is introduced. These results seem compatible with the presence of nanometric structural inhomogeneities (pinholes) in the SiOx layer that were revealed by other studies
Tunc, Deniz. „Synthesis of functionalized polyamide 6 by anionic ring-opening polymerization“. Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0178/document.
Der volle Inhalt der QuelleThe studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening polymerization. By using this strategy, we describe: (i) the synthesis of thermally more stable fluorinated polyamide 6 having a hydrophobic surface; (ii) the synthesis of polyamides 6 bearing pendant cinnamoyl groups, which are thermo-and photoresponsivechromophore groups, and demonstrating their reversible crosslinking as well as improved thermo-mechanical properties; (iii) the copolymerization ofCL with a crosslinker (N-functionalized α-amino-ԑ-caprolactambis-monomers) into crosslinked polyamides 6.As part of our continuing interest in polyamide 6 chemistry, we developed the combination of anionic ring-opening polymerization of CL and chain-growth condensation polymerization of ethyl 4-butylaminobenzoate in order to obtain aliphatic/aromatic polyamides in one-step
Kamdeu, Fansi Alvine A. „Une nouvelle méthode de détection du glaucome par la mesure de l'asymétrie interoculaire : l’asymétrie du rapport de la surface neurorétinienne sur la surface du disque optique ou rim area to disc area asymmetry ratio (RADAAR)“. Thèse, 2009. http://hdl.handle.net/1866/3657.
Der volle Inhalt der QuelleThis thesis describes a new clinical and technological approach to the diagnosis of glaucoma. Specifically, we intend to study a new way to detect glaucoma by measuring rim area to disc area asymmetry ratio (RADAAR). For this purpose, we use a database consisting of a population divided into 4 different diagnostic groups (normal, possible glaucoma, probable glaucoma and definitive glaucoma). The RADAAR measurements are calculated in different ways based on the stereometric parameters of the optic nerve head of subjects, produced by confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph (HRT) (Heidelberg Engineering, Germany)). We conduct an analysis of data with SPSS or we put forward the RADAAR distribution in different populations, its validity in detecting open angle glaucoma and its usefulness in screening for glaucoma. We therefore enroll 523 subjects in this study with about 82 subjects with definitive glaucoma. The average age is 62 years. There are more females than males and more Caucasians than Africans Caraibeans. We find that the distribution of RADAAR measures is different in each diagnosis group. In terms of performance, the sensitivity of the RADAAR measurement is very low. So, its ability to detect the disease is low. However the RADAAR measure is much more specific so, its ability to identify subjects free of the disease is high. RADAAR measure would also be much more effective in African Caribbean’s than in Caucasians. Similarly, it would be much more sensitive in males than in females. The RADAAR measurement is useful if it is combined with another method of diagnosis like the Moorfields regression analysis (MRA) included in the HRT3 software especially in case of the detection of glaucoma in populations at high risk. Ultimately, we determine that the RADAAR is an interesting tool for the diagnosis of glaucoma particularly in the context of screening for glaucoma.