Дисертації з теми "Bruit de spin"
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Bouchiat, Hélène. "Transition verre de spin : comportement critique et bruit magnétique." Paris 11, 1986. http://www.theses.fr/1986PA112055.
Повний текст джерелаThis thesis is devoted to two different problems concerning the spin-glass transition. 1. The first part concerns the study of the critical behavior of the nonlinear magnetization, which is related to the spin-glass-order-parameter singularity at the transition temperature. Our results in the AgMn, CuMn, AgMn Au and CuMn Au spin-glass systems support the existence of a phase transition for which we determine the critical exponents, whose values are different from the mean-field ones. We discuss and investigate the influence of the regular terms and anisotropy on the critical behavior. The study of the non-linear magnetization below Tg suggests that it remains singular near H = 0 over the whole law-temperature phase. Preliminary results in the YEr system raise the question of the coexistence of a spin-glass-like order with long-range antiferromagnetic order. 2. The second part concerns an investigation of the spin-glass dynamics, by studying the magnetic fluctuations without any exciting field. The noise power spectrum is found to vary like 1/f over at least 5 decades of frequency. Its comparison with susceptibility measurements shows the applicability of the linear-response and fluctuation-dissipation theorem to spin glasses when time-correlation functions and response functions are measured when the system is prepared under the same conditions for the two experiments. Aging effects are also investigated
Bouchiat, Hélène. "Transition verre de spin comportement critique et bruit magnétique." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37596281w.
Повний текст джерелаCucchiara, Julien. "Spin transfer effects in nanopillars with perpendicular magnetizations." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10008/document.
Повний текст джерелаThe discover of spin-transfer opens a new way to control the magnetization of a nano-magnet using a spin polarized current instead of a magnetic field. Many studies showed that it is particularly efficient in nanopillar spin-valves with perpendicular magnetizations. Therefore, we decided to analyse into more details the impact of a spin polarized current on these devices during this thesisFirst, we were interested in a global approach of the behavior of these systems based on the understanding of their field and current phase diagrams. Comparing our experimental re-sults with various theoretical predictions, we demonstrated that their main features are ex-plained by a breaking of the uniaxial symmetry of the spin-valves due, for instance, to a non-perpendicular anisotropy axis or applied magnetic field. Moreover, we developed a purely energetic description of these devices allowing to understand simply the physical origin of their behavior.Then, we focused on the magnetization reversal process of these nanopillars dominated by a domain nucleation followed by domain wall propagation. We combined for this study the analysis of a thermally activated phenomenon called telegraph noise, of phase diagrams and of micromagnetic simulations. They all lead to the conclusion that the nucleation process is well described by a Stoner-Wohlfarth behaviour whereas the propagation process seems very dependent on the structure of the domain wall especially for the action of the spin-transfer
Hérisson, Didier. "Mesures de relations de fluctuation-dissipation dans un verre de spin." Paris 11, 2002. https://tel.archives-ouvertes.fr/tel-00002055.
Повний текст джерелаLiu, Shikang. "Spin noise spectroscopy in metatable helium." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP051.
Повний текст джерелаThis PhD thesis mainly addresses the spin noise spectroscopy of metastable helium.We report for the first time the measurement of spontaneous spin noise of metastable helium atom ensemble using non-invasive spin noise spectroscopy.We utilize an off-resonant laser to investigate the random fluctuations of the Zeeman states of the ground level of metastable helium with a mild magnetic field of approximately 1 Gauss. Moreover, we examine the changes in the spectral pattern when the probe approaches the resonance.We investigate the two main types of polarization noise of the probe, namely Faraday rotation noise and ellipticity noise. To replicate the experimental spin noise signal qualitatively and quantitatively, we construct a simulation model that performs well even near resonance.After the investigation of simpler level structure of metastable helium transition line, we extend spin noise spectroscopy to the transition lines with more complicated structures.Our simulation results are consistent with the experimental findings, which are distinct from those obtained using the simpler level structure. To explain the SNS pattern's characteristics near different transition lines, we have developed a comprehensive theoretical model based on the superposition states theory.We then investigate the correlation between Faraday rotation noise and ellipticity noise. Using the eight noise modes of spin-1, we are able to explain the correlation under different conditions. Additionally, we study the effect of magnetic field noise on the SNS pattern. The magnetic field noise is found to alter the noise spectra pattern, and the eight noise modes theory is able to well explain this phenomenon well.This PhD work mainly serves as proof of principle. The simple level structure of metastable helium provids an ideal model to study the phenomenon of spin noise spectroscopy in spin-1 systems. These findings provide a new perspective to understand SNS and the characterization of spin-1 systems, which can aid further research in this area
Neveu, Pascal. "Propagation de lumière dans l'hélium métastable : stockage, amplification, fluctuations et bruit quantique." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN044/document.
Повний текст джерелаA quantum state of light is characterized by its statistics of number of photons. These statistics can change in the presence of coherent phenomena. This PhD focuses both experimentally and theoretically on the propagation of quantum states within a room temperature vapor of metastable helium. First, we show that ultranarrow coherent population oscillations allow to efficiently store a specific quadrature of a light wave. Nevertheless, this protocol cannot be use to store the two quadratures of a light field. Indeed, the propagation conditions deteriorates its statistical properties, forbidding its use for quantum application. Secondly, we show that it is possible to generate twomode squeezed states of light in that system. High amplification can be achieved (9 dB), exploiting the strong nonlinearities enabled by coherent population trapping of a transition, and because of the energy level structure. Finally, we study atomic spin noise transfer to light polarization noise via Faraday effect. These fluctuations, probed by spin noise spectroscopy, show original behaviors that may be useful in another systems
Abbas, Chahine. "Optical spectroscopy of indirect excitons and electron spins in semiconductor nanostructures." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS049.
Повний текст джерелаThis work provides an optical study of spin dynamics in two different systems: electrons gas in n-doped CdTe thin layers, and indirect excitons in asymmetric GaAs coupled quantum wells. Time and polar resolved photoluminescence and pump-probe spectroscopy allowed the determination of both the lifetime and the relaxation time of indirect excitons.The global behaviour of the dedicated biased sample has been described, major technical constraints have been pointed out and optimal working conditions have been identified. In photoluminescence, we obtained a lifetime of 15 ns and a spin relaxation time of 5 ns. Pump-probe spectroscopy with an exceptional delay range shown that longer characteristic times could be obtained increasing the delay between two laser pulses.An other optical method has been used to study electrons in CdTe thin layers. Spin noise spectroscopy has recently emerged as an ideal tool to study dynamics of spin systems through their spontaneous fluctuations which are encoded in the polarisation state of a laser beam by means of Faraday rotation. Common spin noise setups provide only temporal fluctuations, spatial information being lost averaging the signal on the laser spot. Here, we demonstrate the first implementation of a spin noise setup providing both spatial and temporal spin correlations thanks to a wave vector selectivity of the scattered light. This gave us the opportunity to measure both the spin relaxation time and the spin diffusion coefficient. This complete vision of the spin dynamics in CdTe has been compared to our understanding of spin physics in GaAs. Against all odds, this knowledge seems not to be directly transposable from GaAs to CdTe
Quinsat, Michaël. "Etude d'un auto-oscillateur non-isochrone : Application à la dynamique non-linéaire de l'aimantation induite par transfert de spin." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENY083/document.
Повний текст джерелаSpin Torque Oscillators (STO) are nano-sized Radio-Frequency oscillators whose frequency agility can be tuned by an order of magnitude. This tuning originates from the non-linear properties of the underlying magnetization dynamics that is induced by spin transfer torque (STT) in multilayered magnetic nanostructures. Being highly tunable in frequency has the inconvenient of creating a very strong sensitivity to noise. As a result the spectral purity of STOs is far below the one required for applications for instance in telecommunications. The magnetization dynamics induced by STT has been described theoretically in the frame of nonlinear spin wave theory that makes the essential features of the underlying properties very transparent. However important information on the excitation mode are "buried" in phenomenological parameters such as NU the amplitude-phase coupling and Gp the amplitude relaxation rate. Determining these parameters with accuracy from experiments is thus an important issue. This thesis describes several experimental methods to extract these parameters. The first is time domain noise spectroscopy which permits to extract phase and amplitude noise Power Spectral Densities. Their analysis in the frame of theoretical models allows direct extraction of the nonlinear parameters, but also to quantify the technological relevant phase noise. This is demonstrated for magnetic tunnel junction devices. A second method is the analysis of higher harmonics linewidth, where it is shown that due to the non-isochronous property of STOs, the relationship between Dfn and Df1 is non-trivial and allows to extract NU and Gp. We then apply the information gathered on the autonomous dynamics of STOs to understand the non-autonomous dynamics of STOs that are a prerequisite for the use of STOs in complex RF architectures. It is shown experimentally how the nonlinear parameters influence this non-autonomous behaviour
Cucchiara, Julien. "Effets de transfert de spin dans des nanopiliers aux aimantations perpendiculaires." Phd thesis, Université Henri Poincaré - Nancy I, 2011. http://tel.archives-ouvertes.fr/tel-00614929.
Повний текст джерелаWittrock, Steffen. "From noise & stability to synchronization & complex dynamics in spin torque nano-oscillators." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS088.
Повний текст джерелаSpin torque nano-oscillators (STNOs) present unique potential functionalities for rf-communications, energy harvesting or next-generation computing. Therewith, they unify hardware multifunctional key capabilities in the framework of Industry 4.0 and emphasize the potentialities of spintronics, even beyond the paradigm of CMOS. Along with the STNO’s nano-size, radiation-hardness, frequency tunability, low energy consumption and CMOS compatibility, their key characteristics is their strong nonlinearity, which opens up the path to various interesting physical phenomena. However, their nonlinearity also causes the oscillators’ poor spectral coherence, which so far limits their applicability in real practical devices. This PhD thesis aims at providing a deeper understanding of the STNO’s noise in the framework of nonlinearity. Generalizable to all types of spintronic oscillators, we experimentally and theoretically study the contribution of 1/f flicker noise at low frequency offsets in vortex based STNOs. We discuss the influence of this type of noise on the oscillation’s spectral shape and demonstrate potential means for efficient coherence improvements. Moreover, this PhD thesis is also dedicated to the coupling and synchronization of several STNOs, since these capabilities facilitate different applicational schemes in prospective technologies. Indeed, beyond synchronization, novel complex phenomena are experimentally demonstrated and studied, such as the emergence of exceptional points in the coupled system. In summary, the obtained results open up new perspectives not only for the fundamental research on STNOs, but also for novel types of future applications
Polovy, du Souich Hedwige. "Capteurs mixtes pour applications médicales." Paris 6, 2010. http://www.theses.fr/2010PA066087.
Повний текст джерелаAdrados, Claire. "Polaritons en microcavité semi-conductrice : dynamique de fluide quantique, effets de spin et mesures de bruit en régime d'oscillation paramétrique." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00789192.
Повний текст джерелаRéfrégier, Philippe. "Étude de la cinétique lente de l'aimantation des verres de spin isolants : réponse et fluctuations." Paris 11, 1987. http://www.theses.fr/1987PA112321.
Повний текст джерелаVidelier, Hadley. "Détection Térahertz par transistor à effet de champ à base de Silicium." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20241.
Повний текст джерелаThe experimental study reported here, deals with Therahertz (THz) radiation detection with silicon based transistors. After a brief overview of the context and the basics of the theory necessary to understand the subject, the report starts with a comparison betwen high mobility transistors (HEMTs based on III-V technolgies), and silicon transistors (Si-MOSFETs). This study allows a better understanding of the physical phenomenom responsible for THz radiation detection with field effect transistors in general. The second part is focalized on theoretical and experimental study of the critical chanel length (Lc), correlated to the distance of the plasma waves damping, from which the detection signal saturates. Beside, this THz detection signal, from diffrent kind of Si-MOSFETs, has been studied in magnetic field, in temperature, and in the frequency of the incomming radiation. Very pronounced and odd peaks are observed and studied, up to the ambiant temperature, inside the THz signal and the resistance of the MOS submited to magnetic field. These peaks seems to be linked by some way to a spin resonnance with a gyromagnetic factor of 2. The global tendancy of the evolution of the signal in magnetic field is also studied. Finally, one of the first generation of THz optimized detectors, develloped in partnership with CEA-LETI, is presented. Indeed, matrixes of pixels, composed of Si-MOSFETs connected to specific antennas, integrated amplifiers, and a basic reading circuit are studied. Sensitivity, noise equivalent power (NEP), polarization, of these detectors are caracterized. This study demonstrates the whole potential of these silicon based transistors as efficient THz imagery detectors for room temperature
Leyder, Charles. "Optique quantique et dynamique de spin dans les microcavités semiconductrices." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00169855.
Повний текст джерелаNous avons d'abord effectué une étude théorique et expérimentale d'un mélange à quatre ondes dégénéré, sous excitation résonnante par deux faisceaux pompe se propageant en sens inverse, de même polarisation linéaire. Les états finaux du processus ont une polarisation orthogonale à celle des faisceaux pompes et sont fortement corrélés en intensité. Lorsque les deux faisceaux pompes ont des polarisations croisées, le processus est totalement inhibé. Ce processus permet d'utiliser la microcavité comme une porte logique binaire optique.
Nous avons ensuite généré des photons corrélés quantiquement en utilisant un mélange à quatre ondes, sous excitation résonnante par un faisceau pompe, dans une microcavité triple.
Enfin, nous avons étudié l'effet Hall optique de spin et mis en évidence la propagation de courants de spin excitonique sur une centaine de microns.
Grimaldi, Eva. "Étude des propriétés non-linéaires et de l’origine du bruit d’oscillateurs à transfert de spin à base de vortex : vers le développement de nano-dispositifs radiofréquences spintroniques." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112082/document.
Повний текст джерелаThe main goal of this thesis is the understanding of the physical mechanisms and the subsequent control of the properties at the origin of the spin transfer induced magnetic vortex gyrotropic motion in confined systems. In particular the origin of the noise affecting the dynamics has been investigated. This work has been performed with a view to improving the radiofrequency (rf) properties of the so-called Spin Transfer Oscillator (STO).The advantages of such oscillators are their sub-micron size (from few tens to hundreds of nanometres), their compatibility with CMOS technologies and their radiation hardness. Moreover, the magnetization dynamics involved permit a large tunability of frequency as a function of the applied current and a high agility i.e. a fast dynamical response. Nevertheless, several open questions exist regarding the possible optimization of the sustained oscillation conditions and the improvement of the STO power and spectral coherence.The first aspect of my work was to investigate the influence of thermal fluctuations over the sustained vortex core gyrotropic motion. One of the key results of my thesis was to show that the phase noise results from direct phase fluctuations from thermal fluctuations plus amplitude fluctuations converted to phase noise. With an analytical model, we were able to highlight the major role played by the non-linearities of the forces acting on the vortex core. In addition, we were able to measure the characteristic parameters of the oscillator, namely, the speed of frequency response to perturbations as well as the phase-amplitude coupling coefficient.The second important part of my work has been to improve the conditions for obtaining an rf signal. An important result of this work was the measurement of a powerful rf signal in the absence of a magnetic field. The measured powers are a few hundred milliwatts and correspond to low linewidths, ranging from a few hundred kilohertz to a few megahertz. The zero field behaviour was made possible due to the complex structure of the oscillator where the magnetic layer which polarizes the spin current has a perpendicular magnetization, in contrast to the in-plane polarized reference layer.The third step was to optimize the performance of the oscillator. One of the striking results of this thesis is that we measured a record rf output power, up to 3.6 µW, the largest obtained at room temperature for vortex based STOs so far. This high output power results from the development of new FeB based junctions made by the group of Pr. S. Yuasa (AIST, Japan), where the improvement of the quality of the junction allowed us to obtain a magnetoresistance up to 125%.The small size of the oscillator has a cost that is paid in terms of the phase noise. One possible solution that would solve this limitation and enhance the coherence of the oscillations is via mutual synchronization of several STOs through rf currents emitted by each oscillator. Thus, the last stage of my thesis was to study the behaviour of gyrotropic motion when subjected to an alternating current. An important result was to show, through an experimental study in conjunction with an analytical model, the crucial role of the non-linearities and symmetries of the synchronization forces.These various studies have provided us the tools to better understand the dynamics of magnetic vortex and led us to develop an original tester for which the oscillator synchronizes itself with its own rf signal. Depending on the delay at which the oscillator is fed back, we showed for the first time that the frequency, the power and also the linewidth of the oscillations can be modulated
Didier, Herisson. "Mesure de relations de fluctuation-dissipation dans un verre de spin." Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00002055.
Повний текст джерелаLes résultats obtenus montrent en premier lieu une dynamique de quasi-équilibre, confirmant des résultats précédents. Le régime fortement vieillissant est maintenant également atteint. Toutefois, les mesures ne peuvent pas être traduites directement en terme de température effective, car expérimentalement, on observe systématiquement la coexistence d'une dynamique stationnaire et de la dynamique de vieillissement. Une analyse par scaling est proposée pour séparer ces deux contributions. Sous réserve de validité de cette analyse, les mesures confirment alors les principales caractéristiques attendues pour la température effective, et notamment son indépendance en fonction de l'âge du système.
Les différents modèles connus ne permettent cependant pas d'expliquer complètement toutes les caractéristiques de la température effective mesurée, certaines d'entre elles paraissant encore antinomiques...
Cousson, Rémi. "Identification de sources acoustiques au passage d'un véhicule routier par imagerie acoustique parcimonieuse dans le domaine temporel." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI106/document.
Повний текст джерелаThe study detailed in this manuscript is part of the effort to characterize the noise emission from road vehicles. We wish to identify the noise sources of a moving vehicle, when driven on a roadway in real-world conditions, with roadside acoustic measurements. The current acoustic imaging methods do not provide sufficient performance on road vehicles. A state of the art led to the selection of an existing method, MSA-PSF, which consists in deconvolving signals from mobile sources in the frequency domain under certain assumptions, and was originally developed for aeroacoustics. This method is adapted here to the context of road vehicles. Then, an original approach is proposed in order to tackle the specific constraints of this context: CLEANT. This is an iterative method, performed in time domain with a wideband approach, which takes into account the effect of sources motion and includes two parameters designed to refine the result: the loop factor and the stopping criterium. A further version of the algorithm, including a frequency filter, is also proposed and shows significant improvement in identifying secondary sources in some particular cases. An interesting point of CLEANT is the availability of the sources reconstructed time signals, which enables other types of analysis, especially the use of the coherence with signals from on-board measurements in order to separate the contributions of uncorrelated sources. MSA-PSF and CLEANT are evaluated with numerical simulations and a set of indicators to measure their source localization and quantification performance. They are then tested in a controlled laboratory conditions experiment, using a moving source. This experiment represents a first application of the methods to a practical case, involving a linear motion, two simultaneous sources and different kinds of signals (tone and wideband). They are finally compared to the classical approach of moving source beamforming, within the frame of an experiment on a road vehicle, in real-world conditions. The original approach CLEANT yields very encouraging results, and is a clear improvement from the conventional beamforming, especially at low frequency for the tested cases. Applying it to a road vehicle in real-world conditions highlights a potentially troublesome behavior of the method, and the solution brought by CLEANT's frequency filtered version, or by adapting its various parameters. The coherence with reference signals to discriminate the physical origins of the sources is also tested and underlines the role of the short duration of the signals related to the sources passing-by context
Quinsat, Michael. "Etude d'un auto-oscillateur non-isochrone : Application à la dynamique non-linéaire de l'aimantation induite par transfert de spin." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00846484.
Повний текст джерелаPetit, Sébastien. "Influence du couple de transfert de spin sur les fluctuations magnétiques thermiquement activées dans les jonctions tunnel magnétiques." Phd thesis, Grenoble 1, 2007. http://tel.archives-ouvertes.fr/tel-00293055.
Повний текст джерелаDans ce contexte, nous avons montré que le couple de transfert de spin agit fortement sur les fluctuations de l'aimantation à la résonance ferromagnétique dans les jonctions tunnel magnétiques, même pour des courants bien inférieurs au seuil critique. Pour ce faire, nous avons mis en place un banc de mesure de bruit large bande : DC − 26 GHz dont le seuil de détection est inférieur à 0, 5 nV/pHz. De plus, grâce à un modèle développé à partir du théorème de fluctuation-dissipation, nous avons pu expliquer les modifications du spectre des fluctuations magnétiques induites par le courant. Nous avons ainsi pu mettre en évidence l'existence de deux termes de couple de transfert de spin.
Nirrengarten, Thomas. "Piégeage magnétique d'atomes de Rubidium au voisinage d'une surface supraconductrice." Paris 6, 2007. https://tel.archives-ouvertes.fr/tel-00410067.
Повний текст джерелаKontos, Takis. "Transport quantique dans des nanostructures hybrides." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2009. http://tel.archives-ouvertes.fr/tel-00528940.
Повний текст джерелаNirrengarten, Thomas. "Piégeage magnétiques d'atomes de Rudibium au voisinage d'une surface supraconductrice." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00410067.
Повний текст джерелаDes modèles théoriques présentés dans cette thèse laissent penser que l'utilisation de pistes supraconductrices pourrait réduire ces pertes. L'effet du réseau de vortex présent dans le supraconducteur sur le champ magnétique proche de la surface est également étudié. Nous décrivons par la suite le dispositif cryogénique et la séquence expérimentale qui nous ont permis d'observer le premier piège magnétique sur puce supraconductrice. Le temps de vie dans ce piège à 440 micromètres de la surface avoisine deux minutes ce qui est très prometteur. Nous présentons enfin l'étape de refroidissement du nuage jusqu'à l'obtention d'un condensat de Bose-Einstein.
Manninen, P. (Pekka). "Breit-Pauli Hamiltonian and Molecular Magnetic Resonance Properties." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514274318.
Повний текст джерелаFrecus, Bogdan. "Theoretical studies of EPR parameters of spin-labels incomplex environments." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119515.
Повний текст джерелаQC 20130318
Pruvost, L. "Extraction du bruit de combustion d'un moteur Diesel. Développement et application d'un spectrofiltre." Phd thesis, INSA de Lyon, 2009. http://tel.archives-ouvertes.fr/tel-00429987.
Повний текст джерелаReboul, Gabriel. "Modélisation du bruit à large bande de soufflantes de turboréacteurs." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00562647.
Повний текст джерелаDe, Cacqueray Nicolas. "Méthodes numériques pour les écoulements supersoniques avec application au calcul du bruit rayonné par un jet sur-détendu." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00587092.
Повний текст джерелаTartarin, Jean-Guy. "LE BRUIT DE FOND ÉLECTRIQUE DANS LES COMPOSANTS ACTIFS, CIRCUITS ET SYSTÈMES DES HAUTES FRÉQUENCES : DES CAUSES VERS LES EFFETS." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00539034.
Повний текст джерелаLesshafft, Lutz. "Modes globaux non-lineaires et generation de son dans les jets chauds." Phd thesis, Ecole Polytechnique X, 2006. http://pastel.archives-ouvertes.fr/pastel-00002958.
Повний текст джерелаLemoult, Mélanie. "Contribution à l'étude et la modélisation du bruit à large bande à l'éjection des moteurs d'hélicoptères." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00625731.
Повний текст джерелаAdrados, Claire. "Polaritons en microcavité semi-conductrice : dynamique de fluide quantique, effts de spin et mesures de bruits en régime d'oscillation paramétrique." Paris 6, 2011. http://www.theses.fr/2011PA066115.
Повний текст джерелаSameur, Abdelaziz. "Modèle de contact pneumatique/chaussée pour la prévision du bruit de roulement." Phd thesis, Ecole des Ponts ParisTech, 2004. http://pastel.archives-ouvertes.fr/pastel-00001035.
Повний текст джерелаAvril, Gautier. "Etude et optimisation des systèmes à courant porteurs domestiques fac aux perturbations du réseau électrique." Phd thesis, INSA de Rennes, 2008. http://tel.archives-ouvertes.fr/tel-00334464.
Повний текст джерелаBoivin, D. "Systèmes de communications cohérents : estimation du bruit de phase non-linéaire et étude de la modulation de phase duobinaire." Phd thesis, Université de Franche-Comté, 2005. http://tel.archives-ouvertes.fr/tel-00373736.
Повний текст джерелаDans une première partie, l'estimation rapide, analytique ou semi-analytique, de ces fluctuations est proposée dans deux contextes différents. Les résultats alors obtenus par application de la méthode des moments et de la théorie des perturbations sont validés par des simulations numériques de la propagation. Nous menons également une étude expérimentale de l'influence de la carte de dispersion sur le bruit de phase.
Dans une deuxième partie, nous proposons et étudions un format de modulation basé sur la modulation de phase différentielle continue, dans le but d'améliorer l'efficacité spectrale. Ce format est obtenu en modulant la phase optique par un signal à trois niveaux de type duobinaire. Ses performances sont comparées à celles des formats standards au débit de 10 Gbit/s lors d'une expérience utilisant une boucle à recirculation.
Fedala, Djaafer. "Modélisation du bruit à large bande rayonné par un profil isolé : application aux turbomachines." Phd thesis, Paris, ENSAM, 2007. http://pastel.archives-ouvertes.fr/pastel-00003209.
Повний текст джерелаHurault, Jérémy. "Métrologie instationnaire embarquée pour la modélisation du bruit à large bande dans les turbomachines." Phd thesis, Paris, ENSAM, 2010. http://pastel.archives-ouvertes.fr/pastel-00005984.
Повний текст джерелаOjeda, Javier Matias. "Dimensionnement et commande d'actionneurs piézoélectriques en vue du contrôle des vibrations des machines à réluctance variable rapides." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2009. http://tel.archives-ouvertes.fr/tel-00402784.
Повний текст джерелаVolyanskiy, Kirill. "Etudes spectrales du bruit de phase dans les oscillateurs opto-électroniques micro-ondes à ligne à retard." Phd thesis, Université de Franche-Comté, 2009. http://tel.archives-ouvertes.fr/tel-00392571.
Повний текст джерелаAkrout, Akram. "Contribution à l'étude des lasers à verrouillage de modes pour les applications en télécommunications." Phd thesis, Institut National des Télécommunications, 2009. http://tel.archives-ouvertes.fr/tel-01057726.
Повний текст джерелаRivière, Antoine. "Protection des Circuits Intégrés CMOS Profondément Submicroniques contre les Décharges Electrostatiques." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2008. http://tel.archives-ouvertes.fr/tel-00341887.
Повний текст джерелаAubourg, Lucile. "Contrôle et transmission de l'information dans les systèmes de spins." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD003/document.
Повний текст джерелаAt an atomic level, the spin control is an essential aim in quantum physics. Unfortunately, the presence of noises disturbs this last. The goal is to find the conditions which we have to impose to the environment in order that the control is not disturbed by the noise. The study of a spin chain characterized by three couplings (Heisenberg, Ising-Z and Ising-X interactions) freely evolving is taken as reference. We observe that the Heisenberg interaction corresponds to an isotropic coupling. The Ising-Z one conserves the order into the chain whereas the Ising-X one is really disordered. We consider a more complex quantum system by adding some control and analyzing its adiabatic behavior. This last is composed by a system and an environment, for which the coupling is perturbative. Three adiabatic regimes have been highlighted. Some formulas allowing to obtain the wave function across the time have been established for these three regimes. However, in practice, quantum systems are not isolated. The interaction with their environment can lead to more complex behaviors, driving the control more difficult. We have studied spin systems, coupled or not, kicked by some ultrashort magnetic pulse trains. These trains cross a classical environment (stationary, drift, Markovian, microcanonical) modifying the strength and the delay of each pulse. The modification of the trains by the environment is one of the sources of the disorder into the spin system. This disorder is transmitted between the spins by the coupling. In this study we do not succeed in controlling the system when the trains are in the presence of the previous environments. To remedy this situation, we force the magnetic pulses to cross a chaotic environment. Before a time t, called horizon of coherence, the system coupled by an Heisenberg interaction and submitted to a chaotic environment remains coherent whereas after, the population and the coherence of one spin and of the average spin of the system tend to go near the microcanonical distribution. During this horizon, it is possible to realize some quantum control either by total control (control of the system at every instants) or by information transmission. This study allows us to determine an empirical formula of the horizon of coherence. Finally, we have tried to find a more formal approach for this horizon
Karr, Jean-Philippe. "Optique quantique dans les microcavités semi-conductrices. Spectroscopie de l'ion moléculaire H2+." Habilitation à diriger des recherches, Université d'Evry-Val d'Essonne, 2008. http://tel.archives-ouvertes.fr/tel-00347825.
Повний текст джерелаJ'aborde dans la deuxième partie mes activités théorique et expérimentale autour de la spectroscopie de l'ion H2+. Le but de l'expérience, qui a débuté en 2003 à l'université d'Evry, est de mesurer la fréquence d'une transition vibrationnelle à deux photons sans effet Doppler, et de la comparer à des prédictions théoriques précises pour en déduire une nouvelle détermination du rapport mp/me. Je décris les progrès des calculs de haute précision sur l'ion H2+ (niveaux d'énergie non relativistes, structure hyperfine), ainsi que le dispositif expérimental mis en place et les perspectives de l'expérience.
Desvigne, Damien. "Bruit rayonné par un écoulement subsonique affleurant une cavité cylindrique : caractérisation expérimentale et simulation numérique par une approche multidomaine d'ordre élevé." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00589006.
Повний текст джерелаLiang, Chenghua. "Caractérisations électriques de polymères conducteurs intrinsèques Polyaniline / Polyuréthane dans une large gamme de fréquence (DC à 20 GHz)." Phd thesis, Université du Littoral Côte d'Opale, 2010. http://tel.archives-ouvertes.fr/tel-00596089.
Повний текст джерелаVinay, Guillaume. "Modélisation du redémarrage des écoulements de bruts paraffiniques dans les conduites pétrolières." Phd thesis, École Nationale Supérieure des Mines de Paris, 2005. http://pastel.archives-ouvertes.fr/pastel-00001842.
Повний текст джерелаBouhier, Marie Edith. "Amélioration des performances en portée et en précision de localisation angulaire des systèmes de navigation sous-marine." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0122.
Повний текст джерелаFischer, Stéphane. "Développement d'une instrumentation ultrasonore pour la mesure des vitesses des liquides au-delà de la limite de Nyquist par une approche spectrale." Phd thesis, Université Louis Pasteur - Strasbourg I, 2004. http://tel.archives-ouvertes.fr/tel-00011601.
Повний текст джерелаLe signal Doppler étant échantillonné par nature, il est soumis au théorème de Shannon qui impose une vitesse maximale mesurable nommée vitesse de Nyquist. Celle-ci est directement proportionnelle à la fréquence de répétition des trains d'ondes (PRF pour Pulse Repetition Frequency). La profondeur d'exploration est également liée au PRF. Ceci impose la principale limite de cette méthode, à savoir la relation inverse liant la profondeur d'exploration et la vitesse maximale mesurable. Une méthode permettant des mesures de vitesses au-delà de la limite de Nyquist est proposée. Elle se base sur l'utilisation de plusieurs fréquences de répétition des trains d'ondes. Le repliement différent pour chaque PRF permet l'apport d'information nécessaire à la résolution de l'ambiguïté sur les vitesses. Un algorithme original de reconstruction spectrale est proposé. Il permet de recombiner les DSP repliés obtenus pour chaque PRF afin de reproduire la DSP du signal Doppler.
Alkheir, Marwan. "Contrôle du champ acoustique des sons auto-entretenus via la dynamique tourbillonnaire : application au jet plan heurtant une plaque fendue." Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS018.
Повний текст джерелаAn experimental study of a rectangular jet of air impinging on a slotted plate is considered in this work. This study is performed for two Reynolds numbers Re = 5900 and Re = 6700, with an impact ratio L/H=4, where L is the plate-to-nozzle distance and H is the height of the slot. This configuration consists of a flow producing self-sustaining tones. Atypical behavior of the flow through its vortices and acoustic field is found in this study. In order to reduce the noise generation, a control mechanism comprising a 4mm rod is installed in the flow to disturb the vortex dynamics responsible for the loop of self-sustaining tones installed along the jet. A total of 1085 rod positions are tested between the nozzle and the impinged plate in order to find optimal positions. Specific metrologies and codes are developed for appropriate investigations. In particular, a laser technique consisting of double Stereoscopic PIV in a plane « D-SPIV » is employed.In the absence of the rod, in order to visualize the vortex dynamics for both Reynolds numbers Re = 5900 and Re = 6700, SPIV measurements are performed. This allows to characterize these flows in their reference states. For the first Reynolds number (Re = 5900), two self-sustaining tones loops are highlighted. The first has a frequency of 160 Hz and the second has a frequency of 320 Hz. These two loops characterize respectively a symmetric and an asymmetric vortex organization of the jet and alternate in a random pattern with respect to time. The asymmetric regime (f=320 Hz) is more persistent over time. For the second Reynolds number (Re = 6700), the dynamic study of the flow shows that the jet is asymmetric with a vortex shedding frequency equal to 380 Hz, while the more energetic frequency which characterizes the self-sustaining tones of the flow is equal to 168 Hz.When control mechanism is employed through the rod, for both Reynolds numbers, two control zones could be distinguished. The first one is on the axis of the jet. Once the rod is positioned in this zone, the sound pressure level drops by approximately 20 dB. Moreover, the self-sustaining tones loop disappears. When the rod is positioned in the second zone which is located around the lower mixing layer of the jet, the sound pressure level increases by about 12 dB and the self-sustaining tones loop disappears.The study of the dynamics of the flow in the presence of the control mechanism for both Reynolds numbers shows a deflection of the jet when the rod is installed in the second zone (near from the lower mixing layer of the jet). Actually, a part of the vortices escape directly through the slot of the plate without deformation, what explains the disappearance of the self-sustaining loop and the increase of the acoustic level by 12 dB. At the same time, the flow rate through the slot is reduced by about 50%. When the rod is installed in the first zone (on the axis of the jet), no vortices are found to escape through the slot of the plate what explains the disappearance of the self-sustaining loop and the drop in sound pressure level by approximately 20 dB. The vortex activity on both sides of the slot creates recirculation zones in such a way that the flow through the slot is reversed
Florens, Corine. "Modeling of the viscoelastic honeycomb panel equipped with piezoelectric patches in view of vibroacoustic active control design." Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00545422.
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