Relevant bibliographies by topics / Instabilité transversale

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Academic literature on the topic 'Instabilité transversale'

Author: Grafiati
Published: 4 June 2021
Last updated: 5 February 2022

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Journal articles on the topic "Instabilité transversale"

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KATAOKA, TAKESHI. "Transverse instability of interfacial solitary waves." Journal of Fluid Mechanics 611 (September 25, 2008): 255–82. http://dx.doi.org/10.1017/s0022112008002802.

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The linear stability of finite-amplitude interfacial solitary waves in a two-layer fluid of finite depth is examined analytically on the basis of the Euler equations. An asymptotic analysis is performed, which provides an explicit criterion of instability in the case of long-wavelength transverse disturbances. This result leads to the general statement that, when the amplitude of the solitary wave is increased, the solution becomes transversely unstable before an exchange of longitudinal stability occurs.
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KATAOKA, TAKESHI. "Transverse instability of surface solitary waves. Part 2. Numerical linear stability analysis." Journal of Fluid Mechanics 657 (June 17, 2010): 126–70. http://dx.doi.org/10.1017/s0022112010001412.

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In a previous work, Kataoka & Tsutahara (J. Fluid Mech., vol. 512, 2004a, p. 211) proved the existence of longitudinally stable but transversely unstable surface solitary waves by asymptotic analysis for disturbances of small transverse wavenumber. In the present paper, the same transverse instability is examined numerically for the whole range of solitary-wave amplitudes and transverse wavenumbers of disturbances. Numerical results show that eigenvalues and eigenfunctions of growing disturbance modes agree well with those obtained by the asymptotic analysis if the transverse wavenumber of the disturbance is small. As the transverse wavenumber increases, however, the growth rate of the disturbance, which is an increasing function for small wavenumbers, reaches a maximum and finally falls to zero at some finite wavenumber. Thus, there is a high-wavenumber cutoff to the transverse instability. For higher amplitude, solitary waves become longitudinally unstable, and the dependence of the eigenvalues on the transverse wavenumber exhibits various complicated patterns. We found that such eigenvalues versus transverse wavenumber can be simply grouped into three basic classes.
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Jauregui, Cesar, Christoph Stihler, and Jens Limpert. "Transverse mode instability." Advances in Optics and Photonics 12, no. 2 (2020): 429. http://dx.doi.org/10.1364/aop.385184.

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Yeh, Meng Kao, and Kuei Chang Tung. "Dynamic Instability of Delaminated Composite Plates under Parametric Excitation." Key Engineering Materials 326-328 (December 2006): 1765–68. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1765.

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The dynamic instability behavior of delaminated composite plates under transverse excitations was investigated experimentally and analytically. An electromagnetic device, acting like a spring with alternating stiffness, was used to parametrically excite the delaminated composite plates transversely. An analytical method, combined with the finite element method, was used to determine the instability regions of the delaminated composite plates based on the modal parameters of the composite plate and the position, the stiffness of the electromagnetic device. The delamination size and position of composite plates were varied to assess their effects on the excitation frequencies of simple and combination resonances in instability regions. The experimental results were found to agree with the analytical ones.
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Yizhaq, H., I. Katra, J. F. Kok, and O. Isenberg. "Transverse instability of megaripples." Geology 40, no. 5 (2012): 459–62. http://dx.doi.org/10.1130/g32995.1.

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Pelinovsky, Dmitry. "Normal form for transverse instability of the line soliton with a nearly critical speed of propagation." Mathematical Modelling of Natural Phenomena 13, no. 2 (2018): 23. http://dx.doi.org/10.1051/mmnp/2018024.

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In the context of the line solitons in the Zakharov–Kuznetsov (ZK) equation, there exists a critical speed of propagation such that small transversely periodic perturbations are unstable if the soliton speed is larger than the critical speed and orbitally stable if the soliton speed is smaller than the critical speed. The normal form for transverse instability of the line soliton with a nearly critical speed of propagation is derived by means of symplectic projections and near-identity transformations. Justification of this normal form is provided with the energy method. The normal form predicts a transformation of the unstable line solitons with larger-than-critical speeds to the orbitally stable transversely modulated solitary waves.
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Han, Wenhu, Cheng Wang, and Chung K. Law. "Role of transversal concentration gradient in detonation propagation." Journal of Fluid Mechanics 865 (February 22, 2019): 602–49. http://dx.doi.org/10.1017/jfm.2019.37.

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The role of a transversal concentration gradient in detonation propagation in a two-dimensional channel filled with an $\text{H}_{2}{-}\text{O}_{2}$ mixture is examined by high-resolution simulation. Results show that, compared to propagation in homogeneous media, a concentration gradient reduces the average detonation velocity because of the delay in reaching downstream reaction equilibrium, leading to a large amount of unreacted $\text{H}_{2}$ and hence significant species fluctuations. The transversal concentration gradient also enhances the cellular detonation instability. Steepening it reduces considerably the number of triple points on the front, lengthens the global detonation front structure on average and consequently increases the deficit of the average detonation velocity. It is further found that the interaction of the leading shock with the transversal concentration gradient influences the formation of local $\text{H}_{2}$ bump and thus the unreacted pocket behind the front, while the transverse wave causes mixing and burning of the residue fuel downstream. Nevertheless, for the steepened concentration gradient, a transverse detonation is present and consumes the fuel in the compressed and preheated zone by the leading shock; consequently, the detonation velocity deficit is not increased significantly for detonation with the single-head propagation mode close to the limit.
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Krizhevsky, G., and Y. Stavsky. "Refined Dynamic Stability Theory of Laminated Isotropic Circular Plates." Journal of Applied Mechanics 65, no. 2 (1998): 334–40. http://dx.doi.org/10.1115/1.2789059.

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Hamilton’s variational principle is used for the derivation of transversally isotropic laminated circular plates motion. Nonlinear strain-displacements relations are considered. Linearized dynamic stability equations are obtained for circular plates subjected to the same uniformly distributed periodic radial loads. The effects of transverse shear and rotational inertia are included. The exact solutions of vibrations and buckling problems are given initially in the terms of Bessel, power, and trigonometric functions. The vibrational modal functions are used then as a basis in the Galerkin method that reduced the study of dynamic stability to investigation of bounds of instability of Mathieu’s equations. Analytic expressions for the bounds of both principal and combination-type instability regions are obtained using the methods of Bolotin and Tamir. A new effect—sensitivity of certain instability regions to slight imperfections in the symmetry of lamination—is found out and discussed here.
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Shen, I. Y., and Y. Song. "Stability and Vibration of a Rotating Circular Plate Subjected to Stationary In-Plane Edge Loads." Journal of Applied Mechanics 63, no. 1 (1996): 121–27. http://dx.doi.org/10.1115/1.2787186.

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This paper predicts transverse vibration and stability of a rotating circular plate subjected to stationary, in-plane, concentrated edge loads. First of all, the equation of motion is discretized in a plate-based coordinate system resulting in a set of coupled Hill’s equations. Through use of the method of multiple scales, stability of the rotating plate is predicted in closed form in terms of the rotational speed and the in-plane edge loads. The asymmetric membrane stresses resulting from the stationary in-plane edge loads will transversely excite the rotating plates to single-mode parametric resonances as well as combination resonances at supercritical speed. In addition, introduction of plate damping will suppress the parametric instability when normalized edge loads are small. Moreover, the radial in-plane edge load dominates the rotational speed at which the instability occurs, and the tangential in-plane edge load dominates the width of the instability zones.
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Osipov, V. V., and A. V. Severtsev. "Transverse instability of spike autosolitons." Physics Letters A 227, no. 1-2 (1997): 61–66. http://dx.doi.org/10.1016/s0375-9601(97)00013-3.

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Dissertations / Theses on the topic "Instabilité transversale"

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Caceres, Marcos. "Impact of transverse acoustic modes on a linearly arranged two-phase flow swirling flames." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMIR01/document.

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Les besoins énergétiques de la population mondiale ne cessent d’augmenter. Les prévisions indiquent par exemple une forte croissance de la demande du secteur du transport aéronautique. La recherche de systèmes toujours plus performants et moins polluants est nécessaire. Des nouveaux concepts pour la combustion ont été mis au point et appliqués aux turbines à gaz. Parmi eux il existe ceux basés sur la combustion en prémélange pauvre ou en prémélange pauvre pré-vaporisé dans le cas où le carburant utilisé est liquide. Les nouveaux systèmes énergétiques basés sur la combustion en régime pauvre sont prometteurs pour satisfaire les futures normes d’émissions polluantes, mais ils sont plus sensibles aux instabilités de combustion qui limitent leur plage de fonctionnement et peuvent détériorer irréversiblement ces systèmes. Dans ce domaine il reste des questions à aborder. En particulier celle du comportement des flammes tourbillonnaires en combustion diphasique soumises à des perturbations acoustiques. La plupart des moteurs aéronautiques utilisent des flammes de ce type, cependant leur dynamique et leurs interactions mutuelles, quand elles subissent les effets d’une perturbation acoustique, sont loin d’être bien comprises. Ce travail aborde ces questions et apporte des éléments de compréhension sur les mécanismes pilotant la réponse de l’écoulement diphasique et de la flamme, ainsi que des éléments de validation des modèles de prédiction des points de fonctionnement instables. TACC-Spray est le banc expérimental utilisé pour ce travail. Il a été conçu et développé au sein du laboratoire CORIA lors de ce doctorat qui s’inscrit dans le cadre du projet ANR FASMIC. Le système d’injection qui équipe ce banc expérimental reçoit trois injecteurs tourbillonnaires alimentés en combustible liquide (ici n-heptane), développés par le laboratoire EM2C. Ils sont montés en lignes dans le banc, celui-ci représentant ainsi un secteur d’une chambre annulaire. Le montage étant complexe et nouveau, un travail de développement de solutions techniques a été fait pour rendre possible l’équipement du TACC-Spray avec des capteurs de pression, température, photomultiplicateur ainsi que des diagnostiques optiques performants (e.g. LDA, PDA, imagerie à haute cadence). Pour cette étude, le système énergétique, composé par l’écoulement diphasique et la flamme, a été soumis à l’impact d’un mode acoustique transverse excité dans la cavité acoustique. La réponse du système a été étudiée en fonction de son positionnement dans le champ acoustique. Trois bassins d’influence du champ acoustique sur le système énergétique ont été choisis, à savoir: (i) le ventre de pression acoustique caractérisé principalement par des fortes fluctuations de pression, (ii) le ventre d’intensité acoustique présentant de forts gradients de pression et vitesse acoustique, (iii) le ventre de vitesse acoustique avec de fortes fluctuations de vitesse où la fluctuation de pression est résiduelle. L’approche de cette étude a consisté à étudier en premier lieu le système de référence en absence de forçage acoustique, les résultats sont recueillis dans la Partie I de ce manuscrit. En deuxième lieu le système énergétique est placé à chacune des positions d’intérêt dans le champ acoustique et la réponse de l’écoulement d’air sans combustion, la réponse de l’écoulement diphasique avec combustion et finalement celle des flammes, sont étudiées systématiquement. Les résultats de l’étude avec forçage acoustique sont rassemblés dans la Partie II du manuscrit<br>The energy needs of population around the word are continuously increasing. For instance, forecasts indicates an important grow of the request of the aeronautic transportation sector. It is necessary to continue the research efforts to get more performants and less contaminating systems. New concepts for combustion have been developed and introduced to the gas turbine industry. Among these concepts it is found technologies based on lean-premixed combustion or lean-premixed prevaporized combustion when liquid fuels are employed. These novel energetic systems, making use of lean combustion, are promising to meet the future norms about pollutant emissions, but this make them more sensitive to combustion instabilities that limit their operating range and can lead to irreversible damage. In this domain, many questions still need to be considered. In particular that of the behavior of two-phase flow swirling flames subjected to acoustic perturbations. Indeed most of aero-engines operate with this type of flames, but the dynamics and mutual interaction of these flames, as they are submitted to acoustic perturbation, are not yet well understood. This work addresses these issues and gives some understanding elements for the mechanisms driving the response of the flow and of the flame to acoustic perturbations and delivers data to validate models predicting unstable operating points.The experimental bench employed for this work is TACC-Spray. It has been designed and developed in the CORIA laboratory during this PhD thesis which is inscribed in the framework of the ANR FASMIC project. The injections system that equips this bench is composed by three swirled injectors fed with a liquid fuel (here n-heptane), developed by the EM2C laboratory. They are linearly arranged in the bench such that this represents an unwrapped sector of an annular chamber. The setup, being new and complex, needed technical solutions developed during this work and applied then in order to equip TACC-Spray with pressure and temperature sensors, a photomultiplier as well as adequate optic diagnostics (LDA, PDA, high speed imaging systems). In this study, the energetic system, composed by the two-phase swirling flow and the spray flame, has been submitted to the impact of a transverse acoustic mode excited within the acoustic cavity. The system response has been studied as a function of its location in the acoustic field. Three basins of influence of the acoustic field on the energetic system have been chosen, namely: (i) the pressure antinode characterized mainly by strong pressure fluctuations, (ii) the intensity antinode where important acoustic pressure and velocity gradients are present, (iii) the velocity antinode with strong velocity fluctuations where the acoustic pressure is residual. The approach of the study presented here is to investigate in first place the energetic system free of acoustic forcing. The results concerning this first study are presented in the Part I of this manuscript. In second place, the energetic system is placed in each of the location of interest within the acoustic field and the response of the air flow without combustion, that of the two-phase flow with combustion and finally that of the spray flames, are systematically investigated. The results of the study under acoustic forcing are shown in Part II of the manuscript
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Mammeri, Youcef. "SUR QUELQUES MODELES ASYMPTOTIQUES DANS LA THEORIE DES ONDES HYDRODYNAMIQUES." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2008. http://tel.archives-ouvertes.fr/tel-00342347.

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Les équations de Kadomtsev-Petviashvili (KP) décrivent les ondes de faible amplitude et de grande longueur se déplaçant à la surface de l'eau, principalement dans la direction (Ox). Quant à l'équation de Benjamin-Ono (BO), elle décrit de telles ondes se déplaçant à l'intérieur de l'eau. On s'intéresse à ces équations vue en tant qu'équations de type Benjamin-Bona-Mahony (BBM).<br />Notre travail se divise alors en trois parties. Dans la première partie, on rappelle la modélisation des différentes équations. On montre plus particulièrement que les modèles BBM s'obtiennent à partir du principe fondamental de la dynamique via une analyse asymptotique. On compare alors les solutions des équations de KP, respectivement de BO, avec les solutions des équations de type BBM.<br />Dans la seconde partie, on s'intéresse à certaines propriétés qualitatives des équations généralisées de type BBM. Des résultats de prolongement en temps des bornes sur les normes de Sobolev, de décroissance en temps et de prolongement unique des solutions sont établis.<br />Enfin, on termine avec une étude numérique des solutions des équations KP généralisées en dimension 3 d'espace. Dans cette dernière partie, en collaboration avec F. Hamidouche et S. Mefire, on inspecte numériquement les phénomènes de dispersion, d'explosion en temps fini, de comportement solitonique et d'instabilité transversale.
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Boisdron, Gilles. "Etude de l’atomisation d’un jet liquide assisté par air soumis à une onde acoustique stationnaire transverse haute fréquence." Rouen, 2006. http://www.theses.fr/2006ROUES057.

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Les instabilités haute fréquence dans les moteurs fusées impliquent un couplage entre l’acoustique du foyer et la combustion. Cette étude porte sur l’influence d’un champ traverse sur le processus d’atomisation d’un jet liquide assisté par air. Un injecteur coaxial est placé à un ventre de pression (VP) ou de vitesse (VV) d’une onde plane stationnaire limitée à des fluctuations de 3600 Pa. En VP, l’onde impose à l’écoulement gazeux annulaire une modulation pouvant conduire à l’émission d’intenses vortex, permettant au jet liquide de développer une instabilité précoce de type cisaillement. En VV, des effets non linéaires de pression de radiation provoquent l’aplatissement en nappe du corps continu liquide du jet. Un critère, basé sur un nombre de Bond de radiation, détermine son apparition. Elle s’atomise sous l’action d’instabilités intrinsèques de nappe, de Faraday et de rupture de membranes. Enfin, l’acoustique impose à certaines gouttes de rester ou revenir au ventre de vitesse<br>High frequency combustion instabilities ( ˜few kHz) in rocket engines imply a coupling between chamber acoustics and combustion. This study debates on the influence of a transverse acoustic field on the atomization of an air-assisted jet. A coaxial injector is placed at a pressure anti-node (PA) or velocity anti-node (VA) of a stationary plane acoustic wave with maximum fluctuation of 3600 Pa. At hte Pa, the acoustic wave modulates the annular gaseous flow and can induce the emission of intense vortices, which leads to a early shear-stress instability. Placed at a VA, non linear effects due to radiation pressure flattened the jet under the form of a sheet. A criterion, established from a radiation acoustic Bond number, determines its apparition. The sheet is atomised under the action of intrinsic sheet instabilities, Faraday instability and break-up of membranes. Acoustic effects organize the spray: amass and low speed droplets stay or go to the velocity anti-node
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Blimbaum, Jordan Matthew. "Finite element analysis of acoustic wave transverse to longitudinal coupling during transverse combustion instability." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44757.

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Velocity-coupled combustion instability is a major issue facing lean combustor design in modern gas turbine applications. In this study, we analyze the complex acoustic field excited by a transverse acoustic mode in an annular combustor. This work is motivated by the need to understand the various velocity disturbance mechanisms present in the flame region during a transverse instability event. Recent simulation and experimental studies have shown that much of the flame response during these transverse instabilities may be due to the longitudinal motion induced by the fluctuating pressure field above the nozzles. This transverse to longitudinal coupling has been discussed in previous work, but in this work it is given a robust acoustic treatment via computational methods in order to verify the mechanisms by which these two motions couple. We will provide an in-depth discussion of this coupling mechanism and propose a parameter, Rz, also referred to as the Impedance Ratio, in order to compare the pressure/velocity relationship at the nozzle outlet to quasi one-dimensional theoretical acoustic approximations. A three-dimensional inviscid simulation was developed to simulate transversely propagating acoustic pressure waves, based on an earlier experiment designed to measure these effects. Modifications to this geometry have been made to account for lack of viscosity in the pure acoustic simulation and are discussed. Results from this study show that transverse acoustic pressure excites significant axial motion in and around the nozzle over a large range of frequencies. Furthermore, the development of Rz offers a defined physical parameter through which to reference this important velocity-coupled instability mechanism. Therefore, this study offers an in-depth and quantifiable understanding of the instability mechanism caused by transversely propagating acoustic waves across a combustor inlet, which can be applied to greatly improve annular combustor design in future low-emissions gas turbine engines.
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Knuth, Thomas. "Auslegung, Entwicklung und Inbetriebnahme eines longitudinalen und transversalen Feedbacksystems zur Dämpfung gekoppelter Teilchenpaket-Instabilitäten im BESSY-II-Speicherring." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2000. http://dx.doi.org/10.18452/14601.

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Das Auftreten kohärenter Schwingungen gekoppelter Teilchenpakete führt in modernen Elektronenspeicherringanlagen zu einer wesentlichen Beeinträchtigung ihrer Leistungsfähigkeit als Synchrotronstrahlungsquelle. Diese Instabilitäten können in longitudinaler und transversaler Richtung auftreten und führen neben der Verminderung der Brillanz des Synchrotronlichts im ungünstigsten Fall zum Strahlverlust. Das wirkungsvollste Instrument zur Beherrschung der Instabilitäten ist ein Rückkoppelsystem (Feedbacksystem), welches die angeregten Schwingungsamplituden detektiert und dämpft. Diese Arbeit beschäftigt sich mit der Auslegung, der Entwicklung und der Inbetriebnahme zweier von ihrem Aufbau her völlig unterschiedlicher Systeme zur Korrektur von longitudinalen Synchrotronschwingungen und transversalen Betatronschwingungen. Dabei schließt das transversale Feedbacksystem sowohl die horizontale als auch die vertikale Strahlachse ein. Beide Systeme beschränken sich nicht auf die Dämpfung bestimmter Schwingungsmoden, sondern sind so ausgelegt worden, daß alle Teilchenpakete unabhängig voneinander stabilisiert werden. Innerhalb von zwei Jahren konnten alle relevanten Komponenten entwickelt, gebaut und in Betrieb genommen werden. Im Rahmen dieser Arbeit wird auf den Aufbau und die Funktionsweise wichtiger Systembausteine eingegangen und der Prozeß der Inbetriebnahme der Feedbacksysteme erläutert. Meßresultate belegen die Effizienz beider Systeme, die im Nutzerbetrieb kontinuierlich zur Dämpfung von Instabilitäten bei Strömen bis zu 220 mA eingesetzt werden. Der durch die Inbetriebnahme der Rückkoppelsysteme gewonnene Nutzen für die Experimentatoren konnte im Rahmen dieser Arbeit nachgewiesen werden. Damit verfügt BESSY-II über leistungsfähige Feedbacksysteme, die kohärente Schwingungen aller Phasenraumkoordinaten dämpfen und damit die Anforderungen an die Quellgröße einer Synchrotronstrahlungsquelle der 3. Generation gewährleisten.<br>The appearance of coherent coupled bunch oscillations in modern electron storage rings contributes to a significant reduction of the performance as a synchrotron light source. These instabilities occur in longitudinal as well as in transversal directions and lead to a reduction of brilliance and in the worst case to beam loss. The most effective tool for controlling the instabilities is a feedback system, which detects and damps the excited oscillation amplitudes. This thesis describes the development, installation and commissioning of two completely different systems for damping of longitudinal synchrotron oscillations and transversal betatron oscillations. The transverse feedback system incorporates the horizontal as well as the vertical beam direction. Both systems are not restricted to damping certain modes of oscillation, but have been designed for the independent stabilization of all bunches separately. All components have been designed, built and commissioned within two years. In the scope of this thesis the development and the functionality of important components will be explained and the process of commissioning will be described. Measurements emphasize the efficiency of both systems, which are being used continuously for damping instabilities during user operation up to currents of 220 mA. In the scope of this thesis the improved experimental conditions for the user of the synchrotron light could be shown. Consequently, BESSY II possesses two efficient feedback systems which damp coherent oscillations of all phase space coordinates and guarantee the requirements to the source size of a 3rd generation light source.
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Fujimoto, Shinji. "Beam commissioning and suppression of transverse coherent instability at S-LSR." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136765.

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Blyuss, Kostyantyn B. "Perturbed multi-symplectic systems : intersections of invariant manifolds and transverse instability." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/843502/.

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This thesis deals with two aspects of dynamics in systems described by multi-symplectic partial differential equations. The first part is devoted to the study of heteroclinic intersections in systems which govern the dynamics of travelling waves in multi-symplectic partial differential equations with perturbations. In this study a version of the Melnikov method is developed which takes into account the symmetry of the systems under consideration. The presence of the symmetry leads to various interesting differences between the method we develop and the standard approach. In particular, a result about persistence of the fixed point of the Poincare map under perturbations has to be amended since the unperturbed fixed point is non-hyperbolic. The symmetry also results in the necessity to consider separately two cases: when the perturbation has no component in the group direction at all, or when on average it has no component in the group direction when evaluated on the unperturbed solutions. For each of those cases we discuss persistence of the fixed points of the Poincare map and persistence of invariant manifolds, where the knowledge of the symmetry in incorporated in the geometrical constructions. Finally, we derive Melnikov-type conditions in both aforementioned cases which guarantee the existence of transverse intersections of the stable and unstable manifolds. We discuss some possible areas of applications of the Melnikov-type method derived and illustrate the method on the examples of a perturbed Korteweg-de Vries equation and a perturbed nonlinear Schrodinger equation. Implications of the transverse or topological intersections of the manifolds for possible chaotic behaviour in the systems are discussed together with directions of further investigation. The second part of this thesis considers the stability of solitary waves with respect to perturbations which are transverse to the basic direction of propagation of these waves. Using various analytical and numerical techniques, we study this problem for the solitary waves of the (2+l)-dimensional Boussinesq equation and the generalised fifth-order Kadomtsev-Petviashvili equation. For both equations we use a geometric condition for transverse instability based on the multi-symplectic formulation of the equation to derive a condition for transverse instability in the long-wavelength regime. Then an Evans function approach is employed to determine the dependence of the instability growth rate on the transverse wavenumber for all possible wavenumbers. In the case of the (2+l)-dimensional Boussinesq equation this is done analytically, while for the generalised fifth-order Kadomtsev-Petviashvili equation we have to resort to numerical simulations. Finally, for the (2+l)-dimensional Boussinesq equation we perform direct numerical simulations of the full equation to investigate the nonlinear stage of the evolution of the transversely unstable solitary waves, and the result is that the instability leads to the collapse of the solitary wave. The thesis is concluded by a discussion of some open problems.
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Ghani, Abdulla. "Simulation aux grandes échelles des instabilités de combustion transverses des flammes parfaitement prémélangées et swirlées diphasiques." Thesis, Toulouse, INPT, 2015. http://www.theses.fr/2015INPT0068/document.

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Dans cette thèse, les instabilités de combustion sont étudiées sur deux types de configuration. Tout d’abord, un cas académique stabilisé par un dièdre (Volvo) est étudié. Les simulations sont validées par comparaison avec les données expérimentales. En faisant varier le point de fonctionnement, des modes transverses et longitudinaux sont observés, en bon accord avec les données expérimentales en termes de fréquence des fluctuations de pression et de la dynamique de l’écoulement. Dans un second temps, une configuration proche des cas industriels a été étudiée dans le cadre du projet européen KIAI (Lotar). Les données expérimentales ont été obtenues lors d’une campagne d’essais à l’ONERA. Plusieurs simulations aux grandes échelles sont conduites sur cette configuration. Les instabilités transverses de combustion sont analysées et les mécanismes essentiels qui les pilotent sont identifiés. Sur la base de ces observations, la forme du modèle à Fonction de Transfert de Flamme est modifiée et associée à un solveur de Helmholtz pour prédire la stabilité des modes transverses. Les résultats obtenus par le solveur acoustique sont en bon accord avec la carte de stabilité obtenue par la simulation aux grandes échelles<br>In this work longitudinal and transverse combustion instabilities are studied in two types of configurations. While longitudinal modes have been observed in many previous studies at low frequencies, the present work also focusses on high-frequency transverse modes. First, a premixed flame stabilized on a V-fame holder is investigated where experimental results obtained by Volvo are used to validate the simulations. For different operating conditions, longitudinal and transverse modes are observed in Large Eddy Simulations (LES) and show good agreement with the experimental data in terms of pressure frequency and flow dynamics. In a second step, a semi-industrial case is examined within the European project KIAI. Experiments are conducted by ONERA and LES of this two-phase flow configuration (called Lotar) are carried out. Transverse combustion instabilities are analyzed and key elements which drive instabilities are identied. These observations are used to reformulate the classic Flame Transfer Function (FTF) in order to predict the stability of transverse modes by use of an Helmholtz solver. The results reproduce fairly well the stability map generated by LES
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Antunes, José. "Contribution à l'étude des vibrations de faisceaux de tubes en écoulement transversal." Paris 6, 1986. http://www.theses.fr/1986PA066215.

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Analyses dynamiques non-linéaires pour la prédiction des risques vibratoires et d'usure des faisceaux de tubes, et tenant compte du fait que les appuis présentent des variations par rapport aux conditions nominales. Méthodologie permettant l'analyse globale du comportement dynamique non-linéaire des tubes. Simulation des sources d'excitation par l'écoulement. Application aux centrales nucléaires.
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Louis, Frédéric. "Étude de la transition laminaire-turbulent dans des écoulements bi et tridimensionnels supersoniques." École nationale supérieure de l'aéronautique et de l'espace (Toulouse ; 1972-2007), 2004. http://www.theses.fr/2004ESAE0004.

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À la fin du vingtième siècle l’étude d’un avion supersonique de deuxième génération voit le jour. Dans cette optique, les travaux, menés dans le cadre d’un PRF de l'ONERA, s’intéressent à la transition laminaire-turbulent des couches limites supersoniques. En effet les mécanismes de déstabilisation des couches limites, bien connus à des régimes de vitesse faible, restent peu documentés en écoulement supersonique. Trois expériences sont réalisées à Mach 3 afin de créer une base de données inédite sur ces problèmes de transition. Des analyses numériques de stabilité linéaire et non linéaire permettent ensuite de mieux comprendre les phénomènes. La première expérience concerne un écoulement sur plaque plane ; associée à des calculs de stabilité linéaire, elle met en évidence une faible valeur du facteur N de transition provoquée par la réceptivité des couches limites bidimensionnelles aux bruits rayonnés par les couches limites turbulentes se développant sur les parois des souffleries. Les deux autres expériences, respectivement sur un cylindre et sur un profil d’aile en flèche, révèlent une forte réceptivité des couches limites tridimensionnelles aux rugosités pariétales. Les résultats des calculs de stabilité obtenus par des méthodes linéaires locale et non locale, indiquent des niveaux de facteur N de transition plus élevés que ceux des écoulements subsoniques ou transsoniques. Enfin, une analyse de stabilité des ondes stationnaires permet de définir un critère de transition des couches limites tridimensionnelles.
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Books on the topic "Instabilité transversale"

1

Antipov, Sergey A. Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6.

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E, Goldstein Marvin, and United States. National Aeronautics and Space Administration., eds. Nonlinear instability of a uni-directional transversely sheared mean flow. National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. Linear instability of a uni-directional transversely sheared mean flow. National Aeronautics and Space Administration, 1996.

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E, Goldstein Marvin, and United States. National Aeronautics and Space Administration., eds. Nonlinear instability of a uni-directional transversely sheared mean flow. National Aeronautics and Space Administration, 1994.

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Antipov, Sergey A. Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer, 2018.

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Book chapters on the topic "Instabilité transversale"

1

Antipov, Sergey A. "Beam Dynamics Measurements of the Fast Instability." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_2.

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Antipov, Sergey A. "Analytical Model of the Electron Cloud Instability." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_5.

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Buescu, Jorge. "From Attractor to Chaotic Saddle: a journey through transverse instability." In Exotic Attractors. Birkhäuser Basel, 1997. http://dx.doi.org/10.1007/978-3-0348-7421-2_3.

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Antipov, Sergey A. "Electron Cloud in Particle Accelerators." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_1.

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Antipov, Sergey A. "Microwave Measurement of the Cloud Density." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_3.

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Antipov, Sergey A. "Numerical Simulation." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_4.

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Antipov, Sergey A. "Conclusion." In Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets. Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-02408-6_6.

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Metral, E., G. Rumolo, and W. Herr. "Impedance and Collective Effects." In Particle Physics Reference Library. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-34245-6_4.

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AbstractAs the beam intensity increases, the beam can no longer be considered as a collection of non-interacting single particles: in addition to the “single-particle phenomena”, “collective effects” become significant. At low intensity a beam of charged particles moves around an accelerator under the Lorentz force produced by the “external” electromagnetic fields (from the guiding and focusing magnets, RF cavities, etc.). However, the charged particles also interact with themselves (leading to space charge effects) and with their environment, inducing charges and currents in the surrounding structures, which create electromagnetic fields called wake fields. In the ultra-relativistic limit, causality dictates that there can be no electromagnetic field in front of the beam, which explains the term “wake”. It is often useful to examine the frequency content of the wake field (a time domain quantity) by performing a Fourier transformation on it. This leads to the concept of impedance (a frequency domain quantity), which is a complex function of frequency. The charged particles can also interact with other charged particles present in the accelerator (leading to two-stream effects, and in particular to electron cloud effects in positron/hadron machines) and with the counter-rotating beam in a collider (leading to beam–beam effects). As the beam intensity increases, all these “perturbations” should be properly quantified and the motion of the charged particles will eventually still be governed by the Lorentz force but using the total electromagnetic fields, which are the sum of the external and perturbation fields. Note that in some cases a perturbative treatment is not sufficient and the problem has to be solved self consistently. These perturbations can lead to both incoherent (i.e. of a single particle) and coherent (i.e. of the centre of mass) effects, in the longitudinal and in one or both transverse directions, leading to beam quality degradation or even partial or total beam losses. Fortunately, stabilising mechanisms exist, such as Landau damping, electronic feedback systems and linear coupling between the transverse planes (as in the case of a transverse coherent instability, one plane is usually more critical than the other).
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Chang, Hsueh-Chia, and Evgeny A. Demekhin. "Transverse Instability." In Studies in Interface Science. Elsevier, 2002. http://dx.doi.org/10.1016/s1383-7303(02)80034-5.

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Simon, Peter. "Transverse instability of non-adiabatic flames." In Recent Progress in Computational Sciences and Engineering (2 vols). CRC Press, 2006. http://dx.doi.org/10.1201/b12066-171.

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Conference papers on the topic "Instabilité transversale"

1

Khorasanchi, Mahdi, and Shan Huang. "Preliminary Instability-Analysis of Deepwater Riser With Fairings." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79116.

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Instability of deepwater riser with fairings is investigated in this study. Despite the advantages over other devices for suppressing vortex-induced-vibration (VIV), fairings may be susceptible to flutter type instability. A two-body mathematical model is established for the coupled transverse-torsion motion of a top tensioned riser with fairings. The inner part (riser) can only move transversely while the outer part (fairing) has transverse-torsion motion. The effect of the transverse velocity on the angle of attack is taken into account and damping is considered for both degrees of freedom. An eigenvalue analysis is employed to examine the issue of stability. The emphasis is on identifying the critical current speed for a given riser and fairing configuration. The effects of key parameters are investigated and the results indicate that the section hydrodynamic characteristics of the fairings have a significant impact on the instability.
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McCormick, C., R. Y. Chiao, and J. M. Hickmann. "Inverse transverse modulational instability." In Nonlinear Guided Waves and Their Applications. OSA, 2002. http://dx.doi.org/10.1364/nlgw.2002.nltud38.

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Möller, Friedrich, Victor Distler, Maximilian Strecker, Till Walbaum, and Thomas Schreiber. "Backward transverse mode instability?" In Fiber Lasers XVIII: Technology and Systems, edited by Michalis N. Zervas and Cesar Jauregui-Misas. SPIE, 2021. http://dx.doi.org/10.1117/12.2578261.

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Harvazinski, Matthew E., Rohan Gejji, Doug G. Talley, Michael R. Orth, William E. Anderson, and Timothee L. Pourpoint. "Modeling of Transverse Combustion Instability." In AIAA Scitech 2019 Forum. American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-1732.

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Musslimani, Z. H., M. Segev, A. Nepomnyashchy, and Y. S. Kivshar. "Transverse Instability of Coupled Dark-Bright Solitons." In Nonlinear Guided Waves and Their Applications. OSA, 1999. http://dx.doi.org/10.1364/nlgw.1999.wd22.

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Zervas, Michalis N. "Transverse mode instability analysis in fiber amplifiers." In SPIE LASE, edited by Craig A. Robin and Ingmar Hartl. SPIE, 2017. http://dx.doi.org/10.1117/12.2252435.

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Malinowski, Andy, Christophe A. Codemard, and Michalis N. Zervas. "Dynamic BPM model for transverse modal instability." In Fiber Lasers XVIII: Technology and Systems, edited by Michalis N. Zervas and Cesar Jauregui-Misas. SPIE, 2021. http://dx.doi.org/10.1117/12.2582851.

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Shipley, Kevin J., William E. Anderson, Matthew E. Harvazinski, and Venkateswaran Sankaran. "A Computational Study of Transverse Combustion Instability Mechanisms." In 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference. American Institute of Aeronautics and Astronautics, 2014. http://dx.doi.org/10.2514/6.2014-3680.

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Popov, Pavel P., and William A. Sirignano. "Transverse Combustion Instability in a Rectangular Rocket Motor." In 51st AIAA/SAE/ASEE Joint Propulsion Conference. American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-4210.

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Briggs, R. "Low frequency transverse resistive instability in the collider." In Accelerator physics at the Superconducting Super Collider. AIP, 1995. http://dx.doi.org/10.1063/1.47317.

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Reports on the topic "Instabilité transversale"

1

Halling, Mike, P. J. Chou, and Pat Colestock. Transverse instability studies. Office of Scientific and Technical Information (OSTI), 1995. http://dx.doi.org/10.2172/15017149.

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Zhang S. Y. NSNS Transverse Instability. Office of Scientific and Technical Information (OSTI), 1997. http://dx.doi.org/10.2172/1157211.

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Zhang S. Y. TRANSVERSE BUNCHED BEAM INSTABILITY. Office of Scientific and Technical Information (OSTI), 1995. http://dx.doi.org/10.2172/1151329.

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Zhang, S. Y. Transverse and longitudinal microwave instability thresholds. Office of Scientific and Technical Information (OSTI), 1996. http://dx.doi.org/10.2172/437763.

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Heifets, S. A. Transverse instability driven by trapped electrons. Office of Scientific and Technical Information (OSTI), 1995. http://dx.doi.org/10.2172/192496.

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Ng, K. Y. Transverse instability at the recycler ring. Office of Scientific and Technical Information (OSTI), 2004. http://dx.doi.org/10.2172/15020216.

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Balbekov, V. Transverse instability digital damper for the Recycler. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/879094.

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Balbekov, V. Space charge impedance and transverse beam instability. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/879095.

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Burov, Alexey V. Analysis of Transverse Resistive Instability in the Recycler. Office of Scientific and Technical Information (OSTI), 2005. http://dx.doi.org/10.2172/878996.

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Blaskiewicz, M., and W. Weng. TRANSVERSE INSTABILITY WITH LARGE SPACE CHARGE TUNE SHIFT. Office of Scientific and Technical Information (OSTI), 1993. http://dx.doi.org/10.2172/1151287.

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