Дисертації з теми "Bruit – Stabilité"
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Bouyrie, Raphaël. "Influences, stabilité au bruit et déficit isopérimétrique pour des modèles continus et discrets." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30078/document.
Повний текст джерелаThe general topic of this Ph.D thesis is functional and geometrical inequalities, in both continuous and discrete setting. In particular, we make use of the monotone property along the heat flow, which had led to important developments in analysis, geometry and probability since the pioneer work of Bakry and Émery. More recently, this principle has been used in the analysis of Boolean functions in view of application in theoretical computer science. In the first part, we present some multiple integrals inequalities and geometric type inequalities obtained by monotonicity along the heat flow. We characterize, for most of them, equality cases and we put forward rigidity phenomenon in the setting of Riemannian manifolds. In particular, we study rigidity for the Bakry-Ledoux isoperimetric comparison theorem using their semigroup proof. This proof has been exploited by Mossel and Neeman to derive robust dimension free bounds for the Gaussian isoperimetry. We simplify their proof an in particular remove most of Gaussian-specific parts. This gives hope to derive robust estimates to more general log-concave measures or on high dimensional Euclidean spheres. The second part is devoted to analysis of Boolean functions. The principal contribution in this field is the extension of a criterion of Benjamini, Kalai and Schramm linking noise sensitivity and influences of a Boolean function. Such a criterion has been extended recently in continuous setting via the concept of geometric influence. We give a new, semigroup, proof of a quantitative version of it previously established in the discrete cube and in the Gaussian space. This quantitative version generalizes both to various models of Schreier graphs and more general continuous spaces. In particular, the quantitative version over the slices of the Boolean cube has consequences in percolation theory. In the last chapter, we link this quantitative criterion with a generalization over graph products of the "Junta" theorem of Friedgut
Muller, Frédéric. "Simulations de jets propulsifs : application à l'identification des mécanismes générateurs de bruit." Paris 6, 2006. http://www.theses.fr/2006PA066390.
Повний текст джерелаBouchet, Eric. "Étude du bruit d'interaction pale-sillage d'un rotor principal d'hélicoptère." Le Havre, 2002. http://www.theses.fr/2002LEHA0011.
Повний текст джерелаUnderstanding the mecanisms responsible for the BWI noise of helicopter main rotor which occures during perpendicular blade-vortex interaction. An extensive analysis of the blade pressure is performed to get a deeper insight of the BWI mecanism. A stability analysis of modelization of the incident flow (two rectilinear and parallel filaments) is undertaken. The numerical and theoritical results are found to be in good agreement and consistent with the proposed instability hypothesis
Vernotte, François. "Stabilité temporelle des oscillateurs : Nouvelles variances, leurs propriétés, leurs applications." Besançon, 1991. http://www.theses.fr/1991BESA2007.
Повний текст джерелаLeynia, de la Jarrige Émilie. "Sources de bruit actives ultra stables à faible température de bruit pour la radiométrie micro-onde." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1543/.
Повний текст джерелаRadiometers calibration onboard a satellite for Earth observation missions are based on the measurement of reference targets. These reference sources should be able to generate distinct brightness temperatures or noise temperatures. For the cold reference sources, the most common method is to use an external source, like the cold sky. As an alternative, the use of an active cold load (ACL) based on transistor presents several advantages in terms of integration and reduction of complexity of the system. The first part of this report is dedicated to the principles of the radiometry. At first, we remind the essential of remote sensing technics used for Earth observation, then a state of art of different types of radiometer is presented. One of the most important elements for this instrument concerns its calibration. Because of that, a state of art concerning reference sources, and more particularly the active cold loads, is exposed. After all, we notice that, with their low noise level and their frequency range cover, field effect transistors (FET) are good candidates. Thus, we present, in a second chapter, a new type of ACL based on the use of a SiGe heterojunction bipolar transistor (HBT) in L-band. We discuss the technology and topology of the circuit and show the results obtained concerning the adaptation, the noise temperature and the sensitivity to the ambient temperature. In order to compare different technologies on the long-term stability, we also present the conception and the characterization of anACL based on PHEMT GaAs. The third part concerns the realization of a specific radiometer, in order to assess the long-term stability of the developed ACLs. The concept of the radiometer was articulated around two critical points: to limit gain variations of the system in order to increase its stability and to obtain a good sensitivity. In this aim, technological, technical choices and performances of the system are described. At last, the fourth part of this report is dedicated to the study of the long term stability for two developed ACLs. These ones are very stable on the short-term, and present interesting characteristics on the long-term. The approaches concerning the difference in the two circuits in terms of their behavior and performances are discussed
Nguyen, Quôc Sy. "Nanopointes métalliques : étude de la stabilité et du bruit du courant à émission de champ." Lyon 1, 1993. http://www.theses.fr/1993LYO10136.
Повний текст джерелаDupouy, Emmanuel. "Etude et réalisation d’un oscillateur bande X, contrôlé en tension, à varactor MEMS, pour application spatiale." Limoges, 2009. https://aurore.unilim.fr/theses/nxfile/default/0a7b6cfb-c69f-4fd5-bc50-364c054aa7c4/blobholder:0/2009LIMO4006.pdf.
Повний текст джерелаThis research work is dedicated to the design and realization of a 10 GHz voltage controlled oscillator. A feasibility study of the oscillator using MEMS varactor to control the oscillation frequency is realized. First chapter presents analysis methods enabling to simulate accurately all of circuit electrical characteristics before its realization : start-up conditions, steady-state and phase noise analysis. Second chapter presents the non linear modeling of the SiGe heterojonction bipolar transistor used to design the oscillator. Second part of this chapter shows low frequency noise modeling of this transistor, since it’s the major contribution of phase noise near the carrier. Thrid Chapter is devoted to the design of the final oscillator. The different design steps using tools presented in the first chapter and models presented in the second chapter are explained. This work leads to the realization of a fixed frequency oscillator and a voltage controlled oscillator respectively reaching phase noise of -119 dBc/Hz and -115 dBc/Hz @ 100 kHz from the carrier
Leynia, De La Jarrige Emilie. "Sources de bruit actives ultra stables à faible température de bruit pour la radiométrie micro-onde." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00662860.
Повний текст джерелаGuénanff, Ronan. "Couplage instationnaire Navier-Stokes/Euler pour la génération et le rayonnement des sources de bruit aérodynamique." Rennes 1, 2004. https://tel.archives-ouvertes.fr/tel-00068113.
Повний текст джерелаKoenig, Maxime. "Réduction de bruit de jet par injection fluidique en corps central tournant." Poitiers, 2011. http://www.theses.fr/2011POIT2324.
Повний текст джерелаIn this study, we explore a novel jet noise reduction device involving the steady injection of fluid from two diametrically-opposed ports on a rotating centerbody. We observe noise reductions over a low-frequency range up to the rotation frequency for the rotation speeds currently possible. Flow measurements are made with timeresolved stereo PIV for the baseline jet and three control cases with different rotation frequencies (Rotation Strouhal numbers are St=0. 06, St=0. 12 and St=0. 23). Results suggest that the flow can be loosely decomposed into a perturbation area, where changes of the flow are monotonic with the rotation frequency, and a jet response area where the role of the instability modes seems prevailing. It appears that the actuator is efficient in driving a high-intensity mode 2 in the flow. Comparisons are made with the spatial linear stability theory of Michalke. Results suggest : (1) that the noise reduction mechanism may be due to the most unstable flow modes (axisymmetric mode m = 0) being deprived of fluctuation energy due to an excitation of less unstable modes (azimuthal mode m = 2 driven at St=0. 23). (2) Non-linear mechanisms in the flow for the St=0. 12 case lead to an increase of jet noise radiation in the far field. (3) The deformation of the mean axial velocity profile for the St=0. 23 case leads to a mode 0 which is less unstable and this case allows to introduce turbulence in the jet response area rather than wavepackets
Thomas, Isabelle. "Stabilité des transistors MISFET sur InP : Application des mesures de bruit basse-fréquence à la caractérisation des pièges d'interface." Ecully, Ecole centrale de Lyon, 1992. http://www.theses.fr/1992ECDL0045.
Повний текст джерелаBrenes, Alexis. "Modélisation des phénomènes non-linéaires dans un capteur MEMS résonant pour l'optimisation de ses performances et de sa fiabilité." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC072/document.
Повний текст джерелаThe use of MEMS technologies in navigation measurements faces two main challenges.On the one hand, reliability improvement requires a deep understanding of MEMS failure mechanisms. These components are meant for long-term use and are subject to harsh mechanical and thermal constraints during their expected lifetime, usually longer than a decade. On the other hand, the replacement of macroscopic navigation sensors by MEMS components remains impossible as long as the performances of MEMS sensors do not match those of their macroscopic equivalents. With respect to these two challenges, the nonlinear behavior of MEMS resonators is usually seen as an obstacle, if not an insurmountable barrier to technological progress.However, nonlinear phenomena are actually a rich source of potential improvements. At the cost of increased mathematical complexity and specific design efforts, a precise model of MEMS nonlinear behaviors gives access to valuable information about the internal structure of the device. This information may then be used for failure detection and performance optimization.In this thesis, a linear and nonlinear characterization method is developed and experimentally-demonstrated. The knowledge of such nonlinear characteristics allows the determination of optimal operating points in terms of frequency stability and, hence, measurement accuracy
Laloue, Alban. "Modélisation non linéaire distribuée des transistors à effet de champ : application à l'analyse de la stabilité des transistors et des caractéristiques en bruit dans les circuits MMIC millimétriques." Limoges, 2001. http://www.theses.fr/2001LIMO0007.
Повний текст джерелаPorta, Mauro. "Développement, vérification des outils LES pour l'étude du bruit de combustion et de l'interaction combustion / acoustique / turbulence." Toulouse, INPT, 2007. http://ethesis.inp-toulouse.fr/archive/00000507/.
Повний текст джерелаThis work is about the Large Eddy Simulation (LES) of combustion instabilities in industrial burners and, in particular, the assessment of the quality of the results that can be obtained with this approach. The ability of the LES code AVBP of CERFACS to accurately compute simple configurations involving only one physical phenomenon (turbulence, acoustics or combustion) is firstly verified. Reactive and non-reactive academical test cases, for which the analytical solutions are known, are presented putting special emphasis on the influence of the numerical discretization and on its interaction with boundary conditions. Then, having gained confidence in the LES tool, the results obtained from a self-excited computation of a lab-scale burner are shown
Itasse, Maxime. "Effet sur le bruit de jet de l'excitation de modes instables : rôle des interactions non linéaires." Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0028/document.
Повний текст джерелаThis study is part of the effort to reduce aircraft noise during take-off. Jet noise is oneof the main contributors, of which lower frequency component can be attributed to thedirective acoustic field generated by the large-scale coherent structures arising from jetmixing-layer instabilities. The development of these instability waves can be describedusing Parabolized Stability Equations (PSE). A first objective was to determine if inthe case of a natural turbulent jet, nonlinear interactions between instability waveshave a significant impact on its dynamic and acoustic behaviour. For this purpose,a nonlinear PSE model has been developed and applied to a realistic configuration.Then, the possibility to manipulate these instability waves by means of nonlinearity wasinvestigated with a view to reduce noise. To this end, a PSE analysis has been carried outto assess the impact on jet noise of exciting one or more unstable modes. The findingsof this doctoral work demonstrate a minor impact of nonlinearities on the dynamics ofinstability waves for natural turbulent jets on the one hand, and the possibility to makethe initially dominant instability acoustically ineffective using nonlinear interactions onthe other hand
Tricot, Francois. "Analyse et réduction des sources d'instabilitè de fréquence dans une horloge CPT compacte." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS037/document.
Повний текст джерелаThis thesis work has been granted by a CIFRE-Défense contract to study the frequency stabilities of an atomic clock based on coherent population trapping. The objective is to demonstrate a frequency stability in the range of 10-13 tau-1/2 up to 10 000 s. A caesium vapour cell is used with a high-contrast excitation scheme using cross linear polarisations and a Ramsey interrogation. The short-term frequency stability is presented with the reduction of the phase and the laser power noise, both limiting clock performance at 1 s integration time. The optimisation of the microwave chain with a new local oscillator, and the implementation of a very low noise power lock loop have improved the frequency stability down to 2,3x10-13 at 1 s integration time. The fluctuations analysis of the operating parameters (laser intensity, magnetic field, temperature, etc.) and the measurement of the clock frequency show that the medium-term frequency instability is mostly limited by laser power and magnetic field fluctuations at the level of 2x10-14 at 2 000 s integration time. These analyses also show that laser power fluctuations, despite servo loop control, are related to polarisation fluctuations through temperature fluctuations inside the experiment isolation box. Finally, the studies of a dual-frequency and dual-polarisation laser for a compact CPT clock are presented, paving the way to industrialisation by reducing the optical bench
Ansaldi, Tobias. "Compressible single and dual stream jet stability and adjoint-based sensitivity analysis in relationship with aeroacoustics." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/17505/13/Ansaldi_Tobias.pdf.
Повний текст джерелаNoiray, Nicolas. "Analyse linéaire et non-linéaire des instabilités de combustion : application aux systèmes à injection multipoints et stratégies de contrôle." Châtenay-Malabry, Ecole centrale de Paris, 2007. http://www.theses.fr/2007ECAP1049.
Повний текст джерелаCombustion instabilities induced by resonant acoustic-flame coupling occur in manypractical systems and cause severe difficulties and in extreme cases provoke failure or catastrophic damage. In most cases, the combustion process and the flow field are coupled by the system acoustic modes yielding strong oscillations of the flow and release of heat within the system. The problem has been extensively investigated over a number of years and a considerable amount of information has been gathered on the basic driving and coupling mechanisms. The present thesis aims at answering some of pending questions by combining systematic experiments, with theoretical modeling and numerical simulation. Theoretical developments are devised to model the physical phenomena encountered in the experimental layout. Numerical simulations are also used to complement the experimental and analytical work. The important results of this work are : (1) The nonlinear framework relying on the flame describing function (FDF). This constitutes a substantial progress in the understanding of mechanisms yielding limit cycles and of other nonlinear processes such as hysteresis or instability triggering, which are commonly observed in combustion applications. (2) the original passive control strategy which was developped and uses a dynamical phase converter (DPC) to reduce the sensitivity of the flame collection to incident perturbations (patent has been filed on this basis)
Jollet, Cécile. "Expérience NEMO3 : Étude de la stabilité des étalonnages en énergie et en temps du calorimètre : Mesure de la contribution des neutrons au bruit de fond de la double désintégration bêta sans émission de neutrino." Bordeaux 1, 2002. http://www.theses.fr/2002BOR12551.
Повний текст джерелаAvot, Grégoire. "Analyse temporelle des circuits intégrés digitaux CMOS, pour les technologies profondément submicroniques." Paris 6, 2003. http://www.theses.fr/2003PA066009.
Повний текст джерелаBarbagallo, Alexandre. "Réduction de modèle et contrôle en boucle fermée d'écoulements de type oscillateur et amplificateur de bruit." Phd thesis, Ecole Polytechnique X, 2011. http://pastel.archives-ouvertes.fr/pastel-00654930.
Повний текст джерелаFakri, Aboulfida. "Etude numérique de la stabilité spatiale des écoulements de type couche limite : Application à l'étude du bruit rayonné par un profil placé en écoulement sain." Lyon 1, 1985. http://www.theses.fr/1985ECDL0085.
Повний текст джерелаJob, Stéphane. "Etudes théoriques et expérimentales d'un générateur thermoacoustique annulaire à ondes progressives." Le Mans, 2001. http://cyberdoc.univ-lemans.fr/theses/2001/2001LEMA1005.pdf.
Повний текст джерелаThermoacoustic interaction, the interaction between acoustic waves and associated temperature oscillations, is a phenomenon which develops in the acoustic boundary layers, near a wall. This phenomenon is used in thermoacoustic devices (refrigerators and prime-movers). These machines are subjected to growing interest due to potentials applications which appear nowadays. An annular thermoacoustic prime-mover is made of toroidal waveguide. A porous material, along which is maintained a longitudinal temperature gradient, is placed in the waveguide. This increases the volume of acoustic boundary layers for thermoacoustic interaction. Above a given imposed temperature gradient threshold, this device becomes unstable and an acoustic field is spontaneously generated and self-sustained by the thermoacoustic process. In the literature, there is only few works concerning this type of thermoacoustic prime-movers. The goal of the present study is to propose a theoretical modeling of the behavior of such a system in transient and stationary regime. An annular thermoacoustic prime-mover prototype, designed within the framework of these Ph. D. Researches, allowed to validate the proposed theoretical modeling. The analytical study of the transient thermoacoustic instability regime is approached by modeling acoustic propagation in a porous material where arbitrary temperature distribution may be imposed. The unstable behavior of the system is pointed out. The instability threshold condition is analytically determined, and compared to experimental data. The stationary regime behavior is studied. The saturation regime is essentially governed by nonlinear phenomena, among which cascade process of acoustic harmonics excitation and acoustic streaming excitation take important roles. Both these nonlinear effects have been observed in the annular thermoacoustic prime-mover and modeled
Hernandez, Jérôme. "Optimisation des algorithmes de contrôle actif de bruit en conduit pour les systèmes multi-entrées multi-sorties." Toulouse 3, 2004. http://www.theses.fr/2004TOU30119.
Повний текст джерелаThis study is based on FxLMS algorithm implementations for control of noise produced by axial air-fan. Instabilities have appeared because of this primary source variations during modal control of (0,0) and (1,0) modes. Theoretical studies have been done and it is possible to foresee sampling frequency stability intervals. These intervals approach experimental results with 10% errors. Tonal identification, because of lower computation time needs, has allowed Independant Modal and Fully Coupled Controls in real time which have been compared. These two strategies have given equivalent reductions around 14 dB. Results confirm simulations done in previous studies. It has ben shown that modal control is more sensitive to spillover effect maybe because of (0,1) mode disturbations. Coupled control needs more computation power but gives better control quality
Ghosh, Santunu. "Study on the origin of 1/f in bulk acoustic wave resonators." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2046/document.
Повний текст джерелаSince a few decades, frequency control technology has been at the heart of modern day electronics due to its huge areaof applications in communication systems, computers, navigation systems or military defense. Frequency controldevices provide high frequency stabilities and spectral purities in the short term domain. However, improvement of theperformance of these devices, in terms of frequency stability, remains a big challenge for researchers. Reducing noise inorder to increase the short term stability and avoid unwanted switching between channels is thus very desirable. It iscommonly admitted that the fundamental limitation to this short-term stability is due to flicker frequency noise in theresonators. In this manuscript, a first chapter recalls some basic facts about acoustic, crystallography and definitions oftime and frequency domain needed to explore ultra-stable resonators and oscillators. The second chapter is devoted to asummary of the literature on flicker frequency noise. Then, the third chapter concerns our studies on Handel’s quantum1/f noise model, which although criticized by many, is still the only one that provides an estimation of the flooramplitude of 1/f noise that is not invalidated by experimental data. In the fourth chapter, another approach, based on thefluctuation-dissipation theorem, is used in order to put numerical constraints on a model of 1/f noise caused by aninternal (or structural) dissipation proportional to the amplitude and not to the speed. The last chapter is devoted toexperimental results. An ultra-stable resonator used during this study is described. Phase noise measurements on severalbatches of resonators are given. Measurements of resonator parameters have been done at low temperature in order tocorrelate them with noise results. Another approach with a procedure that use transient pseudo periodic oscillations andput to their limits the capacities of presently available digital oscilloscopes, is presented, in order to assess rapidly thequality of various resonators. Finally, conclusions and perspectives are given
Roux, Sébastien. "Influence de la modélisation du mélange air/carburant et de l'étendue du domaine de calcul dans la simulation aux grandes échelles des instabilités de combustion : application à des foyers aéronautiques." Phd thesis, Toulouse, INPT, 2007. http://oatao.univ-toulouse.fr/14175/1/roux_sebastien1.pdf.
Повний текст джерелаDuchiron, Guillaume. "Analyse et conception de résonateurs saphir à modes de galerie pour des applications de métrologie et de filtrage microondes." Limoges, 2001. http://www.theses.fr/2001LIMO0049.
Повний текст джерелаThis thesis is devoted to the study of whispering gallery mode sapphire resonators and to the optimisation of their performances for two distinct applications. The first application is a metrological application for atomic clock PHARAO project. The second topic presented is the realisation of microwave ilters for industrial space applications
Caridi, Jean-Pierre. "Caractérisation des paramètres de frottement à l'origine de phénomènes vibroacoustiques : application aux bruits de crissement des systèmes de freinage." Valenciennes, 2002. https://ged.uphf.fr/nuxeo/site/esupversions/d5381842-8b0f-497b-8acb-65e9a48a83d5.
Повний текст джерелаOur study is the characterization of the frictionnal parameters (application pressure, sliding speed, rubbing coeficient surface state and third body) at the origin of the vibratory instabilities problems resulting to the sharp noise that is the squeal, in the braking area. More particularly, we are studying the influence of these parameters on the signature of the vibrations produced by the friction, in order to find a link. This study has been carried in two part. Firstly, an experimental study using a pin on disc tribometer which has allowed us to see the influence of the parameters on brake squeal. Secondly, finite element analysis has been used to study the influence of the parameters on the stability of the system and on the excited modal shapes via a transient dynamic method. At last, technological solutions are proposed to contribute to conceive less noisy brake systems
Gachon, Dorian. "Nouveaux résonateurs haute-fréquence à Ondes de Volume dans les films minces piézoélectriques pour les Applications sources Embarquées." Phd thesis, Université de Franche-Comté, 2008. http://tel.archives-ouvertes.fr/tel-00578568.
Повний текст джерелаNarbonneau, François. "Dissémination ultra-stable d'étalons de fréquence par fibre optique du réseau télécom métropolitain." Rennes 1, 2007. http://www.theses.fr/2007REN1E004.
Повний текст джерелаHoudebine, Marc. "Contribution pour l'amélioration de la robustesse et du bruit de phase des synthétiseurs de fréquences." Phd thesis, Grenoble INPG, 2006. http://tel.archives-ouvertes.fr/tel-00137092.
Повний текст джерелаLy, Aliou. "Développement d’un oscillateur paramétrique optique continu intense et à faible bruit pour des applications aux communications quantiques." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS528/document.
Повний текст джерелаLong distance quantum communications are limited to few tens of km due to the attenuation of light in telecom fibres. Quantum repeaters (quantum relays synchronized by photonic quantum memories) were introduced in order to increase distances. Or, currently, the most efficient memories do not operate at wavelengths in the telecom C band. In order to take advantage of these memories, the use of quantum interfaces (second order nonlinear medium) was proposed as an alternative. Thus, by adding by sum frequency generation a pump photon at an appropriate wavelength to the telecom photon carrying the information, one transfers the information to a wavelength compatible with these memories, and this with a preservation of the information initially carried by the telecom photon. Our aim is thus to build a continuous-wave singly resonant optical parametric oscillator (cw SRO) which will provide a wave at 1648 nm that will be frequency summed to telecom photons at 1536 nm to transfer the information to a photon storable into alkali atoms based memory. To efficiently transfer the information, the cw SRO has to fulfill some requirements: a high spectral purity (linewidth ~kHz), a high output power (~1 W) and a wavelength longer than that of the telecom photon to be converted. To this aim, we use the non-resonant wave of a cw SRO. The first work done during this thesis was to experimentally prove the possibility to have both high output power and high spectral purity from a cw SRO. By reusing a cw SRO already built during our previous works, we were able to stabilize at the kHz level the frequency of the non-resonant wave at 947 nm (signal wave) of this SRO, with an output power of more than one watt. Then, we built the cw SRO of which non-resonant wave at 1648 nm (idler wave) has been frequency stabilized below the kHz level along with an output power of the order of one watt. We next studied the long term stability of the idler wavelength at 1648 nm. We have measured frequency drifts of the order of 10 MHz/mn. These drifts originating mainly from the reference cavity to which the SRO is locked, can be reduced by, firstly, an active control of the cavity and by, secondly, the use of robust frequency stabilization techniques
Lecavelier, des Etangs-Levallois Aurélien. "Report de technologie SOI-CMOS sur substrat flexible : une approche convergente vers les hautes fréquences et la stabilité des performances sous déformation mécanique." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10058/document.
Повний текст джерелаThe ability to realize flexible circuits integrating sensing, signal processing, and communicating capabilities is of central importance for the development of numerous nomadic applications requiring foldable, stretchable and large area electronics. A large number of these applications currently rely on organic electronics, or integrate high mobility active films on plastic foils to provide higher performance. A key challenge is however to combine high electrical performance (i.e. millimeter wave, low noise electronics), with the mechanical flexibility required to conform to curvilinear surfaces, in addition to high stability of these electrical performance upon deformation. In this work, a solution has been developed, based on thinning and transfer onto plastic foil of high frequency (HF) CMOS devices initially processed on conventional silicon-on-insulator (SOI) wafers. This transfer process first enables the fabrication of high performance electronics on plastic, with n-MOSFETs featuring characteristic frequencies fT/fmax as high as 150/160GHz in addition to low noise potentialities: NFmin/Ga of 0.57/17.8dB. Secondly, by locating the neutral plane of the flexible system in its active layer, the relative variation of these high frequency figures-of-merit can be limited to 5% even after aggressive bending, demonstrating flexibility, high performance and stability
Gonzalez, de Cossio Francisco. "Synthèse d’observateur robuste pour les systèmes non linéaires." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1273.
Повний текст джерелаEstimating the state of a nonlinear system is an essential task for achieving important objectives such as: process monitoring, identification and control. Observers are algorithms that estimate the current state by using, among other information, sensor measurements. The problem of observer design for nonlinear systems has been a major research topic in control for many decades. Recently, there has been an increasing interest in the design of observers for more realistic models, which can include disturbances, sensor nonlinearities and discrete outputs. This thesis concerns the design of robust observers for selected classes of nonlinear systems and we can distinguish three main parts. The first part studies state-affine systems affected by noise, and analyses the state estimation via the so-called high-gain Kalman filter. The convergence properties of this observer are strongly influenced by two variables: its tuning parameter and the properly excited system input. We present a new optimization algorithm, based on Lyapunov analyses, that adapts these variables in order to minimize the effect of both dynamic and output disturbances. The novelty of this approach is that it provides a systematic method of simultaneous tuning and input selection with the goal of improving state estimation in the face of disturbances, and that it avoids the use of trial-and-error based methods. The second part studies the problem of observer redesign for general nonlinear systems whose outputs are transformed by nonlinear functions. Indeed, a given observer might not estimate the system state properly if it does not take into account sensor nonlinearities and, therefore, such an output mismatch needs to be addressed. We present an observer redesign that consists in the interconnection of the original observer with an output estimator based on a dynamic inversion, and we show its asymptotic convergence via small-gain arguments. We illustrate our method with two important classes of systems: state-affine systems up to output injection and systems with additive triangular nonlinearity. Finally, the third part extends our redesign method to systems whose outputs are not only transformed but also discretized in time. This added assumption introduces important challenges; we now implement sample-and-hold techniques leading to an observer gain based on linear matrix inequalities. The main feature of our redesign methods is the possibility to adapt a large number of observers from the literature to more realistic scenarios. Indeed, classical sensors in engineering applications are often nonlinear or discrete, whereas a recurrent assumption in observer design is the linearity or continuity of the output
Lai, Van-Vuong. "Dynamic model of wheel/rail contact for curve squeal simulation." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1I088/document.
Повний текст джерелаSqueal noise of railbound vehicles emitted in tight curves (radius lower than 200m) is characterized by high sound pressure levels at pure medium and high frequencies. State-of-the-art abounds with models trying to simulate curve squeal. However the instability mechanisms are still controversial. In addition, existing curve squeal models are often simplified (analytical frictional contact laws or elastic half-space assumption). The first aim of the thesis is to contribute to a clarification of the possible generation mechanisms. For this purpose, a stability analysis of wheel/rail rolling contact in the case of lateral full sliding is performed by using a point-contact model and wheel/rail modal bases. It is found that, even with a constant Coulomb friction coefficient, the rail vertical flexibility is notably found to play an important role on the instability occurrence without "falling friction" nor without "mode-coupling". The second aim of the thesis is to develop a full Finite Element model of wheel/rail contact in order to compute reference solutions and especially to verify the effects of the simplifications carried out in the point-contact model. Appropriate numerical techniques are used in order to solve the nonlinear discrete equations. In order to reduce the computational effort, reduction strategies are proposed for both domains. The methods are then applied in a realistic wheel/rail model in curve. It is found that the discretization of the contact zone does not substantially modify the instability mechanisms but the divergence rates of the unstable modes due to a stronger coupling between the normal contact degrees of freedom
Giordano, Vincent. "Caractéristiques du signal d'horloge fourni par un résonateur à jet de césium pompé optiquement par diodes laser." Paris 11, 1987. http://www.theses.fr/1987PA112098.
Повний текст джерелаIn this paper, we study from the experimental and theoretical point of view, the clock signal characteristics given by a laser diode optically pumped cesium beam resonator. In the first part, we determine owing to rates equations the best pumping and detection configuration which maximize the clock signal amplitude. In the second part, these theoretical predictions are compared with experiments. We particularly deal with one laser set-up, which is very simple to operate. Its delivers a clock signal with an excellent signal to noise ratio, very promising in atomic clock operation. We finally analyze, in the last part, more sophisticated configurations using several laser sources. They should notably increase the signal to noise ratio, if one reduces the frequency noise of laser diodes used in the experiments. Ln conclusion, this study clearly shows that optical pumping allows an improvement of cesium atomic clock performances
Léon, Olivier. "Étude du rayonnement acoustique d'instabilités hydrodynamiques de jets double-flux par les équations de stabilité parabolisées (PSE)." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/9138/1/leon_partie_1_sur_2.pdf.
Повний текст джерелаHamel, Alain. "Propriétés d'un résonateur atomique à jet de césium pompé optiquement et à structure de champ longitudinale." Paris 11, 1989. http://www.theses.fr/1989PA112204.
Повний текст джерелаLn this thesis, we study from the experimental and theoretical point of view, the clock signal characteristics delivered by a single-laser optically pumped cesium beam resonator. Our new resonator CSIII has been designed in order to avoid drawbacks due to Hanle effect which had arisen with our previous resonator CSII. Several parts have been significantly improved in order to get full benefit from optical pumping advantages. Ln the first part we examine some interesting aspects of the operation of cesium beam resonator i-e : - Determination of Hanle effect free experimental conditions; - Very low C-field resonance; - Experimental study of velocity distribution in the atomic beam; - Observance of extra resonances on the Rabi pedestal. Ln the second part, we determine owing to rate equation the theoretical signal to noise ratio assuming that no extra noise is brought by the laser. We take into account the effect of optical collecting efficiency. These theoretical predictions are compared with experiments on our resonator CSIll. Ln the last part we have measured the short term stability. Ln conclusion, this study clearly shows that optical pumping allows an improvement of cesium atomic clock performances using a single conventional laser diode configuration. Optical pumping is performed this way in our resonator and reaches its theoretical limitations for usual atomic fluxes
Bozdech, Sébastien. "Comportement coopératif de systèmes électrochimiques microstructurés lors d'une réaction bistable." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF003/document.
Повний текст джерелаNonlinear reactions may give rise to new cooperative phenomena when they occur in microstructured systems depending on the size of the active elements and on the coupling between them. We have studied the dynamics of CO electrooxidation, a bistable electrochemical reaction With an S-shaped negative differential resistance on single Pt microelectrode and on their array. For microelectrodes, close to a spatial instability threshold, strong enhancement of the molecular noise was observed due to its interaction With the spatial bifurcation. The dynamic behaviour of the reaction was shown to be strongly affected by the sulfuric acid concentration and by the presence of a small amount of chlorides in solution. When several microelectrodes are globally coupled, the emergence of new cooperative behaviour could be evidenced such as the emergence of coherent oscillations and the presence of a complex dynamic switching regime involving the interplay of inter and intra electrode processes
Bassignot, Florent. "Nouveau type d'oscillateur exploitant des transducteurs à domaines ferroélectriques alternés et des matériaux de guidage pour l'excitation d'ondes ultrasonores d'interface." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00639401.
Повний текст джерелаKanj, Amale. "Etude et développement de la méthode TWSTFT phase pour des comparaisons hautes performances d'étalons primaires de fréquence." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00831596.
Повний текст джерелаGermain, Yves phaede. "Méthode de conception des systèmes différentiels RF utilisant le formalisme des Modes Mixtes." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0010/document.
Повний текст джерелаThis research work aims to develop analytical tools for the analysis and design of differential systems. While the use of differential circuits in RF reception/transmission chains is increasingly growing, there is no accurate method to study their stability. First the common tools to study RF differential components are introduced. Then, the development of a CAD tool that can be rigorously used to investigate the extrinsic stability of linear differential systems is presented. Finally this tool is applied to study the stability of in a real case. The design addresses a three port component that aims to convert the differential output of digital to analog converter into a single-ended access for a spatial application purpose. This broadband active balun is designed using BiCMOS technology. Measurements are performed and the results are in good agreement with the simulation. All the initial specications are achieved, which validate the approach developed in this study
Evain, Clément. "Dynamique de sources sur accélérateur : contrôle de «structures turbulentes» dans les lasers à électrons libres et étude du rayonnement synchrotron cohérent induit par laser." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10171/document.
Повний текст джерелаIn this thesis, we present two studies on the dynamics of accelerator-based sources.The first study concerns the control of ``turbulent patterns'' which appear in some free electron lasers (FEL), and more generally in spatio-temporal systems submitted to a permanent drift. Large drift velocities typically lead to a particular type of instability, characterized by the appearance of noise sustained structures. We show that this type of turbulent behavior can be suppressed by adding a non-local additive feedback. As a remarkable fact, the gain needed for the ``stabilization'' can be extremely small, 10 power -8 for the experiments performed on the UVSOR-II FEL in Japan.The second study is devoted to laser-induced coherent synchrotron radiation (CSR) in a storage ring. In a first step, we show that it is possible to imprint a periodic pattern in the electron bunch phase-space using an external laser. This allow to obtain a tunable coherent emission (CSR) in the terahertz range. Terahertz pulse energy larger by a factor 1000-10 000 with respect to normal (incoherent) synchrotron radiation were thus measured at UVSOR-II. In a second step, we show that this laser-electron beam interaction allows to obtain new information on the CSR instability, which appears when the electron bunch density exceeds a threshold value. In particular, we show experimentally, with the observation of instability precursors, that the instability arises from the amplification of some characteristic wavenumbers
Li, Mingdong. "Etude et réalisation de sources stables microondes à base de résonateur BAW pour micro-horloge atomique au Césium." Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10006/document.
Повний текст джерелаThe objective of this thesis is to study different topologies of low phase noise oscillator as well as a frequency synthesizer at 4.6 GHz for the application of Cs vapor microcell atomic clock. We have studied 7 topologies of low-phase-noise oscillators combined with BAW resonator and 0.25μm SiGe:C BiCMOS Technology from ST Microroelectronics at 2.1 GHz, which present the stat of the art performances. An experimental comparison of these different topologies confirmed the theoretical results. In particular, experimental results showed that the differential topology has better performance in phase noise and is less sensitive to the noise from power supply compared to the single-ended topologies. Finally, a Double-differential-Colpitts topology was proposed, because it was theoretically possible to obtain performance beyond the state of the art in phase noise and in size. Different architectures of frequency synthesizer at 4.6 GHz were studied. We have realized a frequency synthesizer in which a DDS controlled by a FPGA was used. To get good performance in terms of purity of the spectrum, different commercial circuits constituting the frequency synthesis were finely characterized. Finally, the proposed architecture has been used within a completed Cs vapor microcell atomic clock. We got a signal locked with a stability of 2.5 10 – 9 at 1second
Despré, Carole. "Étude expérimentale et numérique du phénomène de tremblement et de son contrôle en écoulement transsonique bi et tridimensionnel." Toulouse, ENSAE, 2001. http://www.theses.fr/2001ESAE0007.
Повний текст джерелаMaury, Rémy. "Réponse d'un jet rond subsonique à une excitation fluidique stationnaire et instationnaire." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2272.
Повний текст джерелаThis work investigates the response of an axisymetric turbulent jet to steady and unsteady fluidic florcing where the azimuthal wavenumber-frequency (!,m) content of the perturbation is well known. The control setup is composed of 16 round microjets azimutally distributed around the nozzle lip. Such actuation can lead to a decrease in the acoustic energy radiated by the jet (especially for the steady case). The aerodynamic fied is investigated using hotwire measurements and time-resolved stereoscopic PIV. Using the unsteady forcing, phase-averaging is possible, and this allows the implementation of a triple decomposition of the measurements. Examination of the cyclic component of the flow response shows that a non-negligible phase-locked fluctuation is obtained over a large spatial extent, in other words, the actuation has good deterministic control authority over the flow. Furthermore, comparison of the cyclic component of the flow response with Linear Stability Theory supports the idea that the jet response comprises linear hydrodynamic instability waves. Subsequent analysis of jets controlled by steady fluidic actuation shows how the control effect can be explained by a mean-flow modification that leads to the reduction of instability-wave growth rates ; the mean flow modification is argued to be due to the introduction of azimuthal wavenumber-frequency pairs to which the mean flow is stable. The response is therefore turbulent, and involves Reynolds stresses which deform the mean-field such that the most unstable modes have lower growth rates
Boudot, Jean-Pierre. "Modélisation des bruits de freinage des véhicules industriels." Ecully, Ecole centrale de Lyon, 1995. http://www.theses.fr/1995ECDL0008.
Повний текст джерелаFacing the customers'requests, manufactures become sensitive to the dynamic design of their products. And moreover the increasing integration of the components induces to consider the optimisation of all elements. Brakes noises, which are prejudicial to the users'acoustic and vibratory comfort, and even sometimes to their safety, belongs to those sensitive phenomena. Heavy trucks judder is an example of a global problem, since the dynamic characteristics of the whole front axle assembly is concerned, even if the source of judder is located in the brake system. This global behaviour is particularly hard since it depends on the geometry of the assembly. That's why the modelling uses a structural phenomenon. The theory, called sprag-slip, is based on dynamic coupling due to buttressing. Such a theory can be implemented on a drum brake or on a disk brake model. These models generate instabilities which are sensitive to the geometrical design of the vehicle. A model representing the whole front axle assembly is built, on the basis of a modal method, combined with sprag-slip. The model is linearized so that a frequential approach is possible, which permits to evaluate the risk of judder versus the design parameters. Theoretical results are compared with some experiments, which show that a stabilisation of the system occurs, due to non-linear effects. With the bond-graph method used here, it is easy to introduce some non-linear effects, and numerical simulations are performed. Finally a theoretical approach takes non-linear effects into account in order to be able to compute, in case of an instability, the magnitude of the stationary cycles, which is a criterion of the instability's seriousness. In the industrial context this work brings me to develop some specific computer tools. They are used now in a practical process to design front axles
Alvarez, Gabriela. "Propriétés interfaciales des composés amphiphiles d'un brut lourd." Paris 11, 2008. http://www.theses.fr/2008PA112311.
Повний текст джерелаEmulsions of heavy oil and water can be encountered at many stages during production, transportation and processing of crude oils and in many locations such as in hydrocarbon reservoirs, well bores, surface facilities, transportation systems and refineries. A good knowledge of petroleum emulsions is necessary for controlling and improving processes at all stages. The complexity of petroleum emulsions comes from the oil composition in terms of surface active molecules contained in the crude, such as asphaltenes, resins and naphthenic acids. We have performed a study of dynamic interfacial tension and rheology of interfaces between water and either crude oil diluted in toluene or a model oil consisting of toluene in which pentane extracted asphaltenes were re-dissolved. We show that the break point of the curve interfacial tension versus asphaltene concentration is related to the collapse of the asphaltenes surface layer. The behavior of diluted crude oil and model oil are quite similar. However, the surface layers evolve over longer timescales in the case of diluted crude oil, probably due to the contribution of resins. We have characterized the structure and conformation of the adsorbed layer, by means of small angle neutron scattering and UV-VIS spectrometry measurements, as well as the asphaltenes charge by zeta potential measurements, in order to study the influence of pH and the ionic force. We found that electrostatic repulsions between asphaltene aggregates play an important role on their adsorption at the water -oil interface, and on their conformational changes at the interfaces. The microscopic properties of the different interfaces and the stability of the corresponding emulsions are well correlated
MOIROT, FRANCK. "Etude de la stabilite d'un equilibre en presence de frottement de coulomb. Application au crissement des freins a disque." Palaiseau, Ecole polytechnique, 1998. http://www.theses.fr/1998EPXX0074.
Повний текст джерелаHoebler-Poteau, Sandrine. "Relations entre les propriétés interfaciales et la stabilité des émulsions de brut lourd." Paris 6, 2006. http://www.theses.fr/2006PA066046.
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