Дисертації з теми "Compression de dynamique"
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Xu, Xiaoqiang. "Modélisation dynamique d'un système frigorifique domestique à compression de vapeur." ENSMP, 1996. http://www.theses.fr/1996ENMP0713.
Повний текст джерелаIn this thesis, a dynamic simulation model and a dynamic exergy analysis of a domestic vapour compression refrigerating system are developed, in order to decrease system energy consumption. The system consists of a compressor, a condenser, a diabatic capillary tube, an evaporator, a capillary tube-suction line heat exchanger and an insulation cabinet. The mathematical model of exchangers is based on mass, momentum and energy conservation equations, in which the refrigerant phase change and the transient and distributive parameters are introduced. The Control-volume formulation and the "SIMPLE C" algorithm are applied in the numerical solutions. The diabatic capillary tube model is distributive and include heat exchange in the tube-suction line exchanger. The critical flow and refrigerant discharge at capillary tube outlet are taken into account. The hermetic compressor model includes lubricant oil effect and heat exchange inside the compressor. The coupling of natural convection and radiation is taken into account in the insulation cabinet model. Once component models have been established, a new iterative solution method for coupling system model is developed. This method presents a "self-convergence" based on the mass balance of exchangers and on compressor and capillary tube characteristics. A method to determine the initial conditon from the refrigerant charge is presented as well. It enables to optimize the system refrigerant charge dynamically over a given operational range. In order to analyze system transient behaviour, a dynamic exergy balance of the refrigeration system has been established. This exergy balance enables to localize and quantify instantaneously system exergy losses, and thus shows the possible system performance improvement. An exergy efficiency for refrigeration system has been defined in order to characterize the thermodynamic perfection of the system in comparison with a correspondent reversible system. The dynamic simulation model and exergy analysis have been used on a domestic regrigerator working with R134a
Sun, Jian. "Allocation dynamique des taches et application parallele a la compression d'images." Paris 11, 1994. http://www.theses.fr/1994PA112231.
Повний текст джерелаBessard, Émeline. "Matériaux composites structuraux à base PEEK élaborés par thermo-compression dynamique : relation procédé-propriétés." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1893/.
Повний текст джерелаThe study objective is to investigate C/PEEK composites manufacturing by thermocompression by gauging two textile semi-products and by taking advantage of the EdyCO pilot capabilities featuring Cage System(r) technology. This process enables to reach high heating and cooling rate and to realise complex thermical cycles that offer new optimisation perspectives of application of thermoplastic resin composites. This work is about the study of manufacturing of two semi-products, the first one being a dry fabric of carbon powdered by PEEK, the other one being a multiaxial of continuous commingled yarns of C/PEEK. The first part of this work is focused on the study of the influence of semi-products and process parameters on consolidation phase of composite plates. Indeed, use of EDyCO pilot enabled to investigate high manufacturing temperature in order to suggest parameters propitious to reinforcement impregnation. The obtained results show that matrix degradation influences consolidation and that commingled structure may be harmful to impregnation. Cooling phase of thermo-compression cycle represents the second part of the this study. Thus, neat and reinforced PEEK crystallization and crystallization kinetics were characterised during anisotherm and isotherm cooling. A unified model was designed to predict crystallization kinetic of both neat and reinforced PEEK. This model describes PEEK crystallization as resulting from the contribution of two mechanisms to debrief of double melting peak phenomena. The influence of degradation is also analysed. To conclude this work, adapted optimal manufacturing cycles are proposed and mechanical properties are evaluated
Amélio, Sandrine. "Evolution microstructurale d'un alliage à base TiAl : sollicitation mécanique par compression dynamique et stabilité thermique." Vandoeuvre-les-Nancy, INPL, 2005. http://docnum.univ-lorraine.fr/public/INPL/2005_AMELIO_S.pdf.
Повний текст джерелаThe aim of this thesis is the study of the microstructural evolution of a γ-TiAl alloy during dynamic compression tests between 196 and 600 °C and isothermal heat treatments at 700 and 900 °C for various times, between 3 and 18 days. The alloy with a nominal composition of Ti-46. 5Al-4(Cr, Nb, Ta, B) (at. %) and a near lamellar microstructure presents a good combination of mechanical strength and ductility. The alloy is compound of three ordered phases: alpha-Ti3Al, gamma-TiAl and B2-TiAl. A study of the crystal structure of the B2, gamma and alpha2 phases, of their the orientation relationships and of the coincidence site lattices and the displacement shift complete lattices has been performed by convergent beam electron diffraction (CBED, Tanaka Multibeam Method and Microdiffraction)
Adalian, Céline. "Comportement du bois en compression dynamique multiaxiale : application à la simulation de crashs de conteneurs." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10614.
Повний текст джерелаWood is a material used a energy absorbing device in containers for the transportation of dangerous materials. The design of these containers is more and more often done with finite element modelling. So, the aim of this research work was to create a numerical model for wood, the "wood model" in order to describe the behaviour of wood under dynamic multiaxial compression. We present experimental results and their analytical modelling for wood under static and dynamic compression which involves large deformations. This "wood model" is based on the experimental results mentioned before. It is used in a finite element explicit non-linear dynamic code. LS-DYNA3D. By this way, we can compare this model with other models used to characterize wood model as impact limiter crashed at 52 to 65 m/s with numerical results made with our wood model and with other numerical materials types used to model the behaviour of wood under compression with large deformations
Maurel, Martin. "Dynamique propagative d’impulsions optiques ultra-courtes pour un module de compression à base de fibre creuse." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0116.
Повний текст джерелаUltra-short pulse laser, hundred femtoseconds, are currently an essential tool for many industrial or academic applications. However, their duration remains limited by the technology which composed this device itself. In addition, development of new microstructured optical fibers offers high-energy pulse guidance in gaseous media, thus allowing the generation of non-linear effects, key parameter for pulse compression and post-compression dynamics. The work of this thesis is therefore part of this context. Studies of ultra-short pulse compression dynamics are presented. Self-compression and post-compression are demonstrated at wavelengths ranging from 343 nm to 1030 nm with energy from few microJoules to several hundred microJoules and average power up to 100 W. Factor 29 of compressions are presented, with solitonic dynamic pulse with duration of 580 fs are compressed down to 19 fs. In addition, this technology has been integrated into an industrial platform installed at various customers' sites
Garabedian, Christian. "Modélisation et caractérisation des générateurs piézoélectriques de conversion mécanoélectrique par compression uniaxiale dynamique ou quasi-statique." Lyon, INSA, 1992. http://www.theses.fr/1992ISAL0097.
Повний текст джерелаThe mechano-electrical energy conversion in a piezoelectric element is achieved differently depending on the stress to be applied. Those differences are further analysed. After a brief summarize of the mechano-electrical conversion, a method leading ta the determination of the electrical parameters is achieved to characterize the piezo-element under dynamic compression conditions. The great differences between the low level coefficients values and those calculated from the experimental measurements lead us to go ahead in the establishment of a model better suite to this conversion and taking into account the dielectric and mechanical lasses as well as the mechanical environment in which the piezo-ceramic is held. This mode yielded the complete characterization of the ceramic working under dynamic compression and its high non linearities. This characterization has been achieved with the help of a computerized simulation. In the second part of this work, the analysis of the slow compression is made. The remaining electric field in the piezo-element yielded a new definition of the value of the electrical energy provided in the spark generation on a compression-decompression cycle and for a given cam position, ta optimize the inter-electrode distance. Then, after a comparison between bath conversion modes, we tried to determine which composition would be better suited in order ta get the higher electrical energy
Padovese, Linilson Rodrigues. "Etude des phénomènes dynamiques dans les pylônes compression des téléphériques monocâble." Grenoble 1, 1992. http://www.theses.fr/1992GRE10207.
Повний текст джерелаSchlumpf, Nicolas. "Adaptation dynamique de la compression d'un amplificateur RF pour des signaux modulés en amplitude et en phase /." [S.l.] : [s.n.], 2004. http://library.epfl.ch/theses/?display=detail&nr=3020.
Повний текст джерелаGuezzi, Messaoud Fadoua. "Analyse de l'apport des technologies d'intégration tri-dimensionnelles pour les imageurs CMOS : application aux imageurs à grande dynamique." Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1022/document.
Повний текст джерелаWith the increase of systems complexity, integrating different technologies together has become a major challenge. Another challenge has traditionally been the limitation on the throughout between different part of the system coming from the interconnections. If traditional two dimensional integration solutions like System In a Package (SIP) bring heterogonous technologies together there is still limitations coming from the restricted number and lengths of interconnections between the different system components. Three Dimensional stacking (3D), by exploiting short vertical interconnections between different circuits of mixed technologies, has the potential to overcome these limitations. Still, despite strong interests for the 3D concepts, there is no advanced analysis of 3D integration benefits, especially in the field of imagers and smart image sensors. This thesis study the potential benefits of 3D integration, with local processing and short feedback loops, for the realisation of a High Dynamic Range (HDR) image sensor. The dense vertical interconnections are used to locally adapt the integration time by group of pixels, called macro-pixels, while keeping a classic pixel architecture and hence a high fill factor. Stacking the pixel section and circuit section enables a compact pixel and the integration of flexible and versatile functions. High Dynamic Range values producing an important quantity of data, the choice has been made to implement data compression to reduce the circuit throughout. A first level of compression is produced by coding the pixel value using a floating format with a common exponent shared among the macro-pixel. A second level of compression is proposed based on a simplified version of the Discrete Cosine Transform (DCT). Using this two level scheme, a compression of 93% can be obtained with a typical PSNR of 30 dB. A validation of the architecture was carried out by the development; fabrication and test of a prototype on a 2D, 180 nm, CMOS technology. A few pixels of each macro-pixel had to be sacrificed to implement the high dynamic range control signals and emulate the 3D integration. The test results are very promising proving the benefits that will bring the 3D integration in term of power consumption and image quality compared to a classic 2D integration. Future realisations of this architecture, done using a real 3D technology, separating sensing and processing on different circuits communicating by vertical interconnection will not need the sacrifice of any pixel to adjust the integration time, improving power consumption, image quality and latency
Duguet, Yohann. "Simulation numérique de l'instabilité dans un cylindre de gaz tournant soumis à une compression périodique." Ecully, Ecole centrale de Lyon, 2004. http://www.theses.fr/2004ECDL0021.
Повний текст джерелаThis work concerns the direct numerical simulation of a new instability phenomenon occuring in confined rotating gas flows. It confirms the analytical results of J. F. Scott and J. P. Racz (2001) and the experimental work of L. Graftieaux (2003). A parametric resonance mechanism leads to conditional growth of inertial mode pair coupled by harmonic oscillations of a piston. A numerical code was developed under the assumption of axisymmetry of the flow, based on a galerkin-type spectral method. Special treatment of the velocity singularities in the cylinder corners is based on the substraction of an analytical lly specified flow the mimics the corner singularities. The results allow complete characterization of inertial mode pairs coupled by resonance, with particular attention focused on the primary axisymmetric mode studied experimentally. A marginal stability diagram and an exploration of the nonlinear regime were performed
Duguet, Yohann Scott Julian. "Simulation numérique de l'instabilité dans un cylindre de gaz tournant soumis à une compression périodique." Ecully : Ecole centrale, 2004. http://bibli.ec-lyon.fr/exl-doc/yduguet.pdf.
Повний текст джерелаMalo, Alexandre. "Chargement dynamique par composants pour réseaux de capteurs adaptables." Mémoire, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6194.
Повний текст джерелаChiriac, Dragos. "Le contrôle de la compression, de la prise de son au matriçage : une approche intégrée pour l'examen de problèmes relatifs à la perte de la gamme dynamique causée par la compression lors du matriçage." Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30682/30682.pdf.
Повний текст джерелаThis study is interested in the means of obtaining loud mixes, particularly in musical genres where such practices are pertinent (electronic music and hip-hop, in our case), while avoiding the usual disadvantages and defects of loud mixes. In other words, we are seeking for ways to achieve loud tunes from the listener’s subjective perception, without encountering distortions caused by the squaring of the waves’ amplitudes, usually associated with the heavy usage of compressors and limiters, and without loosing to much dynamic variety and/or dynamic range (the range between the lowest and the highest value [dB] in a mix). For these endeavours we have tried three different—yet parallel—autonomous methods. These are: 1) Sound design in function of our subjective perception of loudness (psychoacoustics); 2) Dynamic control of percussions for an efficient compression at the mastering stage; 3) Mixing and mastering at the same time.
Daniel-Gautier, Hélène. "Evaluation de deux procedes de granulation de la vancomycine associee a un substitut osseux : la compression isostatique et la compaction dynamique (doctorat : pharmacotechnie et biomateriaux)." Nantes, 2000. http://www.theses.fr/2000NANT02VS.
Повний текст джерелаCharpail, Estelle. "Analyse du comportement mécanique des côtes humaines en dynamique." Phd thesis, Paris, ENSAM, 2006. http://pastel.archives-ouvertes.fr/pastel-00002983.
Повний текст джерелаMaysonnave, Thomas. "Etude d’un système d’amplification de puissance de type multiplicateur de courant dynamique sur l’installation SPHINX du CEA Gramat." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3050/document.
Повний текст джерелаFor several decades, high power generators are used in various fields such as materials research, radiography or inertial confinement fusion. These generators are capable of delivering current pulses of several millions of amperes with rise times below 1 microsecond. Several projects around the world are, today, trying to improve again and again the current gradient of pulses delivered to the load. Many concepts of power amplifiers, whose role is to optimize both the amplitude of the load current and its rise time, were tested. The Dynamic Load Current Multiplier (DLCM) is one of those innovating concepts used to overcome the existing pulsed power generators limitations. It is made up of concentric electrodes (for autotransformer), a dynamic flux extruder (based on the implosion of cylindrical wire array) and a vacuum closing switch. In this these, the operating principle of the DLCM is theoretically analyzed through electrical and magneto hydrodynamic simulations. A specific study of the DLCM key component is performed. This is the vacuum closing switch. Thus, after a design phase using electrostatic simulation tools, two versions of switches are experimentally validated in conditions similar to those of a very high current shot. Finally, shots on the SPHINX facility located at the CEA Gramat, capable of delivering a current pulse of 6MA in 800ns (on Z-pinch load), are exposed to trace the evolution of this device. The convincing results are used, ultimately, to validate the DLCM concept connected to an isentropic compression experiment load
Kouassi, Joseph. "Contribution à l'auscultation dynamique des superstructures par les mesures de la célérité et de l'atténuation des ondes planes élastiques : application au béton." Châtenay-Malabry, Ecole centrale de Paris, 1989. http://www.theses.fr/1989ECAP0116.
Повний текст джерелаZaki, Larbi. "Reponse dynamique d'un milieu quasi-fragile modelisation et aspects mathematiques application a la compression et a la flexion du beton." Orléans, 1996. http://www.theses.fr/1996ORLE2072.
Повний текст джерелаHou, Bing. "Dynamic enhancement and multi-axial behavior of honeycombs under combined shear-compression." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2011. http://tel.archives-ouvertes.fr/tel-00675750.
Повний текст джерелаOuarem, Abdelouahab. "Comportement mécanique et évolutions microstructurales sous compression quasi-statique et dynamique de polycristaux CFC et HC : effet de la taille des grains." Paris 13, 2012. http://scbd-sto.univ-paris13.fr/intranet/edgalilee_th_2012_ouarem.pdf.
Повний текст джерелаThe present work is devoted to the analysis of the strain rate and grain size effects on the deformation mechanism activated during plastic deformation of two polycrystalline materials: (i) zinc (Zn), a crystal with hexagonal compact packing structure, having grain size in the micro and ultrafine grain ranges (~ 300 µm and 200 nm, respectively), loaded under quasi-static and dynamic compression conditions, up to a strain rate of ~ 10⁵ s⁻¹ (by use of a Direct Impact Hopkinson Pressure Bars (DIHPB); (ii) electrodeposited nickel (Ni), a face-centered cubic structure with grain size of 5 µm deformed in compression under dynamic conditions using DIHPB. Significant differences in terms of micro-mechanisms of deformation in the two regimes were found: (i) At lower strain rates, up to ~ 10² s⁻¹, dislocation-based plasticity was observed in both Ni and Zn. Extensive twinning occurred only in the case of micrometer grain-sized Zn, indicating a grain size dependence of twinning; (ii) In the dynamic regime (> 10³ s⁻¹) plastic deformation induced a significant increase of the temperature within the samples. This increase of temperature was significant enough to induce recovery and/or dynamic recrystallization. As consequence two phenomena were observed depending on the structure under investigation: for Ni, the resulting microstructure and mechanical properties were similar to that of the initial state, dominated by annealing twins and equiaxed and randomly oriented grains. For micro-grained Zn a tremendous grain refining was found. As a consequence, twinning was inhibited. To clarify this point, additional investigations were carried out on coarse-grained CP-Ti deformed in both quasi-static and dynamic regimes. It was found that twinning was the main deformation mechanism. Indeed, the larger the strain rate and grains size, the larger the twin density. On the one hand, these results clearly demonstrate the grain size effect on the occurrence of mechanical twinning in HCP materials. On the other hand, the effect of the strain rate on twinning was found to depend on the material under investigation. Compared to Ti, the lower homologous temperature T/T m of Zn probably plays a key role, as it may induce dynamic recovery/recrystallization as far as the present experimental conditions are concerned
Moysan, Véronique. "Traitement des fractures du massif trochantérien de l'adulte par vis-plaque à compréssion dynamique CORSO : Club des orthopédistes du Sud-Ouest : à propos de 130 cas." Bordeaux 2, 1990. http://www.theses.fr/1990BOR25280.
Повний текст джерелаPicard, Mathieu. "Dynamique des gaz et combustion du Rim-Rotor Rotary Ramjet Engine (R4E)." Mémoire, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/1607.
Повний текст джерелаWouts, Jérémy. "Étude et modélisation du comportement en compression du bois sous sollicitations d'impacts." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0025.
Повний текст джерелаWood is a natural cellular material, which is widely and advantageously used as shock absorber for the transport of radioactive materials. Accident situations are evaluated based on the 9 m drop test, which allows us to observe the complex crushing behavior of wood. A compressive experimental study is conducted on spruce and beech wood species over a large range of strain rates (from 0.001 to 600 s−1) to investigate the effect of the loading direction and of two extreme lateral confinements. The longitudinal direction is the most sensitive to the effect of strain rate and of lateral confinements which have significant consequences on the energy absorption. Besides, the experimental investigation can be adapted to various wood species with very different mechanical properties. A strain rate dependent elastoplastic model with transversal isotropy is developed using multi-scale and micromechanics techniques. The elastic macroscopic properties of wood are estimated with a Mori-Tanaka scheme and information extracted from the microstructure. The Gurson type criterion based on the micromechanical approach of the ductile damage is used in order to describe the non linear behavior of wood, its densification regime and its compressibility as well. Additionally, uncoupled degradation parameters are applied to reproduce the failure mechanisms involved in the longitudinal response. A simplified description of wood is used within the modeling and the numerical results exhibit the good ability of the model to reproduce the various wood responses during an accident situation
Yang, Hyun-Kyu. "Contribution à l'étude de matériaux composites sollicités par barres de Hopkinson, (en compression, traction et cisaillement), à grande vitesse de déformation." Nantes, 1993. http://www.theses.fr/1993NANT2101.
Повний текст джерелаHmima, Abdelhamid. "Dynamique non-linéaire dans les oscillateurs optoélectroniques micro-ondes." Université de Franche-comté. UFR des sciences et techniques, 2012. http://www.theses.fr/2012BESA2042.
Повний текст джерелаThis work is part of the effort undertaken in order to improve the performance of optoelectronic oscillators (OEOs) with delay line optical _ber. This OEO was recently introduced and rapidly gained a great interest for several research laboratories in the world. This is due to its great spectral purity which is required for micro-wave radars and geolocalisation systems. We studied the standard architecture using optical _ber delay line in order to deal with the speci_cs of the OEO at time-frequency and optics domain interface. Frequency stability levels achieved by the OEO are interesting. Therefore we explored the potential of a new architecture of OEO that takes advantage on nonlinear dynamics. Indeed this architecture can deliver in addition of the microwave signal, optical pulses with very short duration and low time jitter. This is made possible by the spectral properties of the OEO and the by introducing temporal compression and optical regeneration techniques. These pulses operate at telecommunications wavelengths, particularly at 1:55 _m. This type of OEO with optical compression can be dedicated to Optical Time Division Multiplexing (OTDM) systems. We have experimentally determined a spectral purity, respectively, -60 and -140 dBc/Hz at 101 and 2_104 Hz from 10 GHz carrier. The optical pulses generated at 10 GHz repetition rate have 4. 1 ps durations with a time jitter of 2. 7 and 83 fs respectively in the ranges [1 to 10 kHz] and [10 Hz to 100 kHz]. This work opens the way to the use of other nonlinear phenomena to improve the spectral purity of microwave oscillators
Liu, Yi. "Dynamics, Synchronization and Spin Squeezing in a Two-Spin Model." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112216.
Повний текст джерелаThis thesis focuses on the dynamics of a cold atomic system which consists of two internalstates of atoms trapped in a magnetic trapping potential. The motivation of this thesis is aseries of experiments on such system carried out in 2010, where a surprising longcoherence time between the two internal states were observed. This phenomenon wasexplained by the kinetic theory which has used a mean-field approach. In this thesis, wetry to use a different approach and study the effects of quantum correlations in thedynamics of the system. In addition to that, we are also interested in the phenomenon ofspin squeezing which is the redistribution of quantum fluctuations in the spin system. Inorder to study the effects of the quantum correlations, we propose a simplified which splitsthe cold atoms into two groups based on their orbital movement energies in the trappingpotential and treat each group as a macro-spin. The main ingredients in this model are theinhomogeneity of the external field which dephases the two macro-spins and theexchange interaction between the two macro-spins, which mimics the identical spinrotation effect (ISRE), with the initial condition that the two spins lie parallel in thetransverse plane of the external field. Then we study the classical dynamics of the systemwhere the dynamics do not depend on the size of the spins and a synchronizationtransition is found when the exchange interaction is larger than the threshold, the half ofthe inhomogeneity of the external field. A phase space analysis reveals that thissynchronization transition is related to a bifurcation transition and the initial condition. Thenthe quantum dynamics is studied where the spin size plays an important role in thedynamics. There is no synchronization transition in the quantum systems and very richdynamical behavior is found. In the quantum dynamics, many characteristic time scalesemerge as the size of spin is increased, which are of quantum origin. These time scales isdependent of the spin size and all become infinite when the size of spin is infinite. In theway, the classical limit is recovered. Based on the strength of the exchange interaction,two effective models are proposed to calculate the smallest quantum characteristic timescales, which give very good agreement with the numerical results. Spin squeezing is alsostudied with these effective models
Grenier, Etienne. "Evaluation des effets physiologiques, neurophysiologiques et comportementaux liés au port de bas médicaux de compression." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0130.
Повний текст джерелаMedical compression therapy is recognized as an essential component in the treatment of venous diseases and is indispensable in the treatment of venous diseases at different stages of the disease (heavy legs, edema and ulcers). Although the benefit is recognized by the patients themselves and by physicians, there is at present little evidence to quantify this benefit. Against this background, the aim of this thesis is to provide more understanding and objectify the benefits of compression stockings (MCS) on in terms of physiology, neurophysiology and gait dynamics. Three areas of research were identified and studied. The first line of research is the study of the effect of compression on skin microcirculatory activity in the lower limbs using the Hematron ambulatory device. The results showed an improvement in skin blood flow activity for different classes of MCS and at different positions. These results would tend to challenge the widely accepted assumption that MCS improve venous return primarily by decreasing the cross-sectional area of (superficial or deep) veins. The second line of research involves the objectification of the improvement in the quality of life resulting from the wearing of MCS, usually this is expressed subjectively by people with venous disease. Preliminary results show that the analysis of heart rate variability highlights a relationship between the indicators of sympathovagal balance activity and the use of medical compression during the day. Given the wide dispersion in the results, this study should be carried out on a larger population to draw more reliable conclusions. The last line of research relates to the impact of MCS on the behavior and, in particular, the gait of the subject. Patients report that physical fatigue in the lower limbs is less prevalent at the end of the day with compression therapy. Our hypothesis is that the wearing of MCS has a direct impact on gait. To evaluate the kinetics of walking, we have designed, developed and validated an instrumentation involving accelerometers sensors. Preliminary tests have yielded relevant parameters characteristic of gait dynamics. The next step is to conduct an experimental campaign to objectify behavioral fatigue, with or without the wearing of medical compression, at the end of the afternoon
Zinszner, Jean-Luc. "Identification des paramètres matériau gouvernant les performances de céramiques à blindage." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0337/document.
Повний текст джерелаSince the sixties, ceramics are commonly used as armour materials. Indeed, thanks to their interesting physical and mechanical properties, they allow a significant weight benefit in comparison to monolithic steel plate armours. However, the microstructure of the ceramic may have a strong influence on its penetration resistance. Based on characterisation tests and on the use of four silicon carbide grades, this work aims to highlight the links between the microstructure and the ballistic efficiency. Experimental compressive and spalling tests are based on the use of the GEPI device. For studying the compressive dynamic behaviour, it allows using the lagrangian analysis method and characterising the yield strength of the material. For studying the tensile dynamic behaviour, it allows assessing the strain-rate sensitivity of the spall strength. An analysis of the fragmentation process is performed based on Edge-On Impact tests. Moreover, an innovating impact test on fragmented ceramics has been designed and performed. The different experimental results allow a better understanding of the influence of the ceramic microstructure on its behaviour under the different loadings. All the experimental data have been compared to numerical results allowing validating the constitutive models. The DFH (Denoual-Forquin-Hild) damage model of brittle materials showed very good capacities to simulate the tensile dynamic behaviour of ceramics (spalling and fragmentation)
Nakano, Tamon. "Étude numérique de l’interaction choc/couche limite en géométrie de révolution." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2018. http://www.theses.fr/2018ESMA0013/document.
Повний текст джерелаShock wave/boundary layer interactions (SWBLI) are present in various aerospace engineering applications.They can be associated with separated regions yielding low-frequency unsteadiness, which have mainly been studied in planar geometries. The present study aims at characterizing this type of interaction in a cylindrical configuration. A direct numerical simulation solver has been developed and validated with various test cases. It is based on a high-order finite difference based hybrid schemes (6th order centered scheme/5thorder WENO), extended to curvilinear geometries. Transverse curvature effects on properties of spatially developing supersonic boundary layer at Mach 3 are first examined. It is shown that the increase of the relative curvature of the boundary layer tends to reduce the fluctuation energy at lower frequencies near the wall, while reinforcing the perturbations at higher frequencies in the upper zone of the boundary layer.In comparison with the planar case, the transverse curvature leads to a significant re-organization of the boundary layer structures and a subsequent modified behavior of the invariants of anisotropy turbulent stress tensor. It however only leads to slightly modified distributions of Reynolds stress and a rather similar overall balance of turbulent kinetic energy through the boundary layer. The second part of this study is dedicated to the unsteady motions of the shock/separation zone in a cylinder/compression flare configuration for which the full cylindrical geometry is taken into account. The shock distortions in the azimutal direction appears to be mainly associated to the organization of the upstream vortex structures and the subsequent azimutal fluctuations of the separation line. It is shown that the energy of the fluctuating wall pressure is more amplified for higher order azimutal modes. The contributions to lateral forces, associated to the first mode, are dominated by low-frequencies only upstream of the separation line in the intermittent region. They become more dominant in the middle frequency range downstream of the reattachment zone on the ramp. It is also shown that the low-frequency activity at the wall is progressively due to higher order azimuthal modes through the interaction zone
ZHOU, XIAO-WEI. "Contribution au comportement dynamique des materiaux metalliques : etude experimentale de l'alliage al-li en torsion et en compression, simulation numerique du processus de penetration a grande vitesse." Nantes, 1988. http://www.theses.fr/1988NANT2014.
Повний текст джерелаZhou, Xiao Wei. "Contribution au comportement dynamique des matériaux métalliques étude expérimentale de l'alliage Al-Li en torsion et en compression : simulation numérique du processus de pénétration à grande vitesse /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37619358w.
Повний текст джерелаCourbon, Cédric. "Vers une modélisation physique de la coupe des aciers spéciaux : intégration du comportement métallurgique et des phénomènes tribologiques et thermiques aux interfaces." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00713527.
Повний текст джерелаHentati, Manel. "Reconfiguration dynamique partielle de décodeurs vidéo sur plateformes FPGA par une approche méthodologique RVC (Reconfigurable Video Coding)." Rennes, INSA, 2012. http://www.theses.fr/2012ISAR0027.
Повний текст джерелаThe main purpose of this PhD is to contribute to the design and the implementation of a reconfigurable decoder using MPEGRVC standard. The standard MPEG-RVC is developed by MPEG. Lt aims at providing a unified high-level specification of current and future MPEG video coding technologies by using dataflow model named RVC-CAL. This standard offers the means to overcome the lack of interpretability between many video codecs deployed in the market. Ln this work, we propose a rapid prototyping methodology to provide an efficient and optimized implementation of RVC decoders in target hardware. Our design flow is based on using the dynamic partial reconfiguration (DPR) to validate reconfiguration approaches allowed by the MPEG-RVC. By using DPR technique, hardware module can be replaced by another one which has the same function or the same algorithm but a different architecture. This concept allows to the designer to configure various decoders according to the data inputs or her requirements (latency, speed, power consumption,. . ). The use of the MPEG-RVC and the DPR improves the development process and the decoder performance. But, DPR poses several problems such as the placement of tasks and the fragmentation of the FPGA area. These problems have an influence on the application performance. Therefore, we need to define methods for placement of hardware tasks on the FPGA. Ln this work, we propose an off-line placement approach which is based on using linear programming strategy to find the optimal placement of hardware tasks and to minimize the resource utilization. Application of different data combinations and a comparison with sate-of-the art method show the high performance of the proposed approach
Maghraoui, Ahmed. "Génération d'harmoniques d'ordre élevé pour l'étude de la dynamique des charges et de l'aimantation de films de cobalt." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE010/document.
Повний текст джерелаThe goal of this thesis is to develop an harmonic source to cover the energy range of 50-70 eV of the electromagnetic spectrum by high harmonic generation in a rare gas. This source called "tabletop" is obtained from a femtosecond laser system based on the chirped pulse amplification technique. Such source allows probing the magnetization dynamics at the M-edges of transition metals. The interest to probe the magnetization dynamics with X-rays is the chemical selectivity on the elements. This, one can probe the spin dynamics of the chemical element which are responsible for magnetism. For example, in a system containing several elements, one can reach the magnetic properties of each one of its components by adjusting the photon energy to the absorption edge of the element
Valle, Medina Maria Elena. "Modélisation des décanteurs secondaires : étude en mécanique des fluides numériques de la dynamique de la sédimentation des boues activées." Thesis, Strasbourg, 2019. https://publication-theses.unistra.fr/public/theses_doctorat/2019/VALLEMEDINA_MariaElena_2019_ED269.pdf.
Повний текст джерелаThe conventional activated sludge process is the most widely used process for treating urban wastewater. Biomass (activated sludge) grows and forms biological flocs that must be separated from the treated water. This is usually performed by gravity in a clarifier. Activated sludge particles are subject to different settling processes, depending on their properties. Clarifier simulation is probably the most developed field of application for computational fluid dynamics applied to wastewater treatment. However, all sedimentation mechanisms are not always fully represented. This work began by adding the compression mechanism as a second-order term in the partial differential equation describing sludge sedimentation. The parameters of the modified model were identified based on experimental data from a closed system. Then, simulations of a full-scale clarifier allowed the model to be validated based on the measured sludge blanket height and particle velocity profiles. Small treatment plants are characterized by very dynamic inlet conditions (flow variations, on/off cycles). Thus, the validated model was used to simulate these operating conditions
El proceso de lodos activados convencional para el tratamiento del agua residual es el más usado para remover los contaminantes del agua residual urbana. La biomasa (lodo activado) crece y forma flocs biológicos que deben ser separados del agua tratada. Normalmente esta acción se realiza por medio de la gravedad en un sedimentador. Las partículas de lodo activado pueden someterse a diferentes comportamientos de sedimentación dependiendo de sus propiedades. La simulación de los clarificadores secundarios es probablemente el área más desarrollada para la aplicación de la mecánica de fluidos computacional en el tratamiento del agua residual. Sin embargo, no todos los mecanismos de sedimentación están siempre representados en un modelo. Este trabajo presenta la adición de la compresión como un término de segundo orden en una ecuación diferencial parcial que describe la sedimentación del lodo. La identificación de los parámetros del modelo se realizó a través de experimentos realizados en un sistema cerrado. Luego, simulaciones en un clarificador a escala real permitieron validar el modelo basándose en la medición de la altura del manto de lodos y los perfiles de velocidad de las partículas. Estaciones depurados de pequeña capacidad se caracterizan por una dinámica discontinua de las condiciones de entrada (variaciones en el caudal, ciclos de encendido/apagado). Así el modelo validado se usó para simular estas condiciones operacionales
Abbou, Jeremy. "Développement d'une microscopie électrochimique (SECM) à l'échelle du nanomètre par couplage avec la microscopie à Force Atomique (AFM) : application à l'étude de la compression et de la dynamique de chaînes linéaires de polyethylène glycol immobilisées par une de leur extrémité à la surface d'un substrat d'or : vers une microscopie électrochimique à médiateur lié à la sonde." Paris 7, 2004. http://www.theses.fr/2004PA077001.
Повний текст джерелаLi, Yun. "Etats comprimés de Spin dans un condensat de Bose-Einstein." Paris 6, 2010. https://tel.archives-ouvertes.fr/tel-00506592.
Повний текст джерелаLlave, Adrien. "Amélioration de la compréhension de la parole et de l’écoute spatiale pour les malentendants appareillés." Electronic Thesis or Diss., CentraleSupélec, 2022. http://www.theses.fr/2022CSUP0003.
Повний текст джерелаHearing aids are designed to restore the essential abilities of hearing, the most important of which is speech intelligibility. This is achieved mainly through two functions: compensating for hearing loss and reducing the noise level. Noise reduction and hearing loss compensation are performed one after the other. However, both have antagonistic objectives and introduce artifacts that are detrimental to the apprehension of a complex auditory scene in its entirety. In a first step, we unify the formalism underlying the denoising and loss compensation algorithms in order to develop an explicit solution to the problem as a whole, for an auditory scene composed of one speech source and an ambient noise. In a second step, we focus on a better preservation of the interaural localization cues for all spatial directions. For this purpose, we develop three methods based on approximations of the cost function related to the interaural transfer function preservation. Finally, we extend the auditory scene model to several speech sources and ambient noise. The context of hearing aids makes this case difficult to handle due to the small number of microphones. We propose to exploit the sparsity property of speech in the time-frequency domain to overcome this obstacle
Grange, Sébastien. "Expérimentation et modélisation de l'endommagement sous chargements dynamiques de deux roches calcaires." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2007. http://tel.archives-ouvertes.fr/tel-00505334.
Повний текст джерелаMozelle, Gérard. "Compression de donnees multiples et dynamiques." Paris 5, 1998. http://www.theses.fr/1998PA055005.
Повний текст джерелаMammou, Khaled. "Compression de maillages 3D statiques et dynamiques." Paris 5, 2008. http://www.theses.fr/2008PA05S007.
Повний текст джерелаStatic and dynamic 3D meshes are widely exploited by professional and general public applications (e. G. , CAD, telemedicine and video games). This Ph. D. Thesis proposes four original approaches to compress 3D meshes: two of them handle static models and the other two the dynamic ones. The first method, called TFAN (Triangle FAN-based compression), aims at efficiently coding 3D meshes under a low decoder complexity constrain. The TFAN codec was recently retained (April 2008) for a future ISO/MPEG standardization. The second approach is dedicated to dense 3D meshes. It exploits a B-Spline approximation (with connectivity preservation) coupled with a JPEG2000 encoding. The B-Spline approach offers high compression performances for low bitrates while ensuring the functionality of quality scalability. The third technique, called MCGV (Multi-Chart Geometry Video), compresses dynamic 3D meshes. It exploits a geometry-images-based representation compressed by using the standard encoders JPEG and MPEG-4. The MCGV approach ensures high compression performances for low bitrates while supporting advanced functionalities (e. G. , streaming and scalability). Finally, the fourth contribution of the Ph. D. Thesis concerns the FAMC (Frame-based Animated Mesh Compression) compression method, which exploits a skinning-based motion compensation strategy. Because of its high compression performances and the complete set of functionalities it supports, the FAMC technique was promoted as an ISO/MPEG standard
Gautier, Josselin. "Un modèle d'attention visuelle dynamique pour conditions 2D et 3D ; codage de cartes de profondeur et synthèse basée inpainting pour les vidéos multi-vues." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00758112.
Повний текст джерелаMartin-Gassin, Gaelle. "Etude statique et dynamique par réflectance linéaire et Génération de Second Harmonique de films de molécules et de nanoparticules métalliques à l'interface air / eau." Phd thesis, Université Claude Bernard - Lyon I, 2007. http://tel.archives-ouvertes.fr/tel-00150850.
Повний текст джерелаLi, Yun. "États comprimés de spin dans un condensat de Bose-Einstein." Phd thesis, Ecole Normale Supérieure de Paris - ENS Paris, 2010. http://tel.archives-ouvertes.fr/tel-00506592.
Повний текст джерелаAzzouz, Kamel. "Etude d'un système frigorifique domestique à haute inertie thermique avec matériau à changement de phase." Paris 6, 2008. http://www.theses.fr/2008PA066007.
Повний текст джерелаDenay, Anne-Gaëlle. "Mécanismes et tenue mécanique long-terme de mousses polyuréthanes pures et renforcées aux températures cryogéniques." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2012. http://tel.archives-ouvertes.fr/tel-00740110.
Повний текст джерелаMondelin, Alexandre. "Modélisation de l'intégrité des surfaces usinées : Application au cas du tournage finition de l'acier inoxydable 15-5PH." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00838512.
Повний текст джерелаSalson, Mikaël. "Structures d'indexation compressées et dynamiques pour le texte." Rouen, 2010. http://www.theses.fr/2010ROUES042.
Повний текст джерелаLion, Nicolas. "Caractérisation mécanique de la glace aéronautique sous chargement rapide et développement d'une loi de comportement pour simuler des impacts de glace." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI028.
Повний текст джерелаIn order to guarantee the safety of passengers and aircrafts, numerous studies have been financed in recent years by the aerospace and aeronautics industry in order to characterize experimentally and then numerically simulate the ingestion by the aircraft engines of projectiles. Ice is an example of projectile that can impact aircraft engines during the fly. In this research framework, our work objectives are the high-speed experimental characterization of aeronautical ice and the developpement of a model that will simulate ice impacts on a structure. A synthesis of the various existing research and work on ice makes possible to take stock of the current knowledge of the ice material and to point out its weaknesses, in particular the lack of experimental data on aeronautical ice. Production protocols for different types of ice, sample processing protocol, transport method, electromechanical press test bench and split Hopkinson bars were developed. They make it possible to better understand the behavior of ice at high deformation velocities (influence of microstructure, influence of temperature and influence of deformation velocity). The last part details a model of behavior and general rupture applicable to fragile materials and more particularly to the ice under impact. It is a law of behavior elasto-damagebale with Mazars damage type, associated with modifications of Chuzel for its use in fast dynamics. The method of identifying the parameters of the law from the tests is also presented. The implementation of the law in the commercial code LS-Dyna is validated on simple cases before the numerical results are compared to the experimental results. This comparison has highlighted a defect inherent in the Mazars model of damage. A correction of the model is therefore proposed