Bibliografie tematiche / Periodic and quasi-Periodic media

Letteratura scientifica selezionata sul tema "Periodic and quasi-Periodic media"

Autore: Grafiati

Pubblicato: 8 giugno 2024

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Articoli di riviste sul tema "Periodic and quasi-Periodic media":

Su, Xifeng, e Rafael de la Llave. "KAM Theory for Quasi-periodic Equilibria in One-Dimensional Quasi-periodic Media". SIAM Journal on Mathematical Analysis 44, n. 6 (gennaio 2012): 3901–27. http://dx.doi.org/10.1137/12087160x.

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Pang, Gen-Di. "Optical properties of quasi-periodic media". Journal of Physics C: Solid State Physics 21, n. 31 (10 novembre 1988): 5455–63. http://dx.doi.org/10.1088/0022-3719/21/31/016.

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Sinai, Yakov G. "Anomalous transport in quasi-periodic media". Russian Mathematical Surveys 54, n. 1 (28 febbraio 1999): 181–208. http://dx.doi.org/10.1070/rm1999v054n01abeh000120.

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Su, Xifeng, e Rafael de la Llave. "KAM theory for quasi-periodic equilibria in 1D quasi-periodic media: II. Long-range interactions". Journal of Physics A: Mathematical and Theoretical 45, n. 45 (19 ottobre 2012): 455203. http://dx.doi.org/10.1088/1751-8113/45/45/455203.

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Kimura, S., G. Schubert e J. M. Straus. "Instabilities of Steady, Periodic, and Quasi-Periodic Modes of Convection in Porous Media". Journal of Heat Transfer 109, n. 2 (1 maggio 1987): 350–55. http://dx.doi.org/10.1115/1.3248087.

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Instabilities of steady and time-dependent thermal convection in a fluid-saturated porous medium heated from below have been studied using linear perturbation theory. The stability of steady-state solutions of the governing equations (obtained numerically) has been analyzed by evaluating the eigenvalues of the linearized system of equations describing the temporal behavior of infinitesimal perturbations. Using this procedure, we have found that time-dependent convection in a square cell sets in at Rayleigh number Ra=390. The temporal frequency of the simply periodic (P(1)) convection at Rayleigh numbers exceeding this value is given by the imaginary part of the complex eigenvalue. The stability of this (P(1)) state has also been studied; transition to quasi-periodic convection (QP2) occurs at Ra ≈ 510. A reverse transition to a simply periodic state (P(2)) occurs at Ra ≈ 560; a slight jump in the frequency of the P(2) state occurs at Ra between 625 and 640. The jump coincides with a second narrow (in terms of Ra) region of quasi-periodicity.

de la Llave, Rafael, Xifeng Su e Lei Zhang. "Resonant Equilibrium Configurations in Quasi-Periodic Media: KAM Theory". SIAM Journal on Mathematical Analysis 49, n. 1 (gennaio 2017): 597–625. http://dx.doi.org/10.1137/15m1048598.

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de la Llave, Rafael, Xifeng Su e Lei Zhang. "Resonant Equilibrium Configurations in Quasi-periodic Media: Perturbative Expansions". Journal of Statistical Physics 162, n. 6 (8 febbraio 2016): 1522–38. http://dx.doi.org/10.1007/s10955-016-1464-5.

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Gao, Yixian, Weipeng Zhang e Shuguan Ji. "Quasi-Periodic Solutions of Nonlinear Wave Equation with x-Dependent Coefficients". International Journal of Bifurcation and Chaos 25, n. 03 (marzo 2015): 1550043. http://dx.doi.org/10.1142/s0218127415500431.

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This paper is devoted to the study of quasi-periodic solutions of a nonlinear wave equation with x-dependent coefficients. Such a model arises from the forced vibration of a nonhomogeneous string and the propagation of seismic waves in nonisotropic media. Based on the partial Birkhoff normal form and an infinite-dimensional KAM theorem, we can obtain the existence of quasi-periodic solutions for this model under the general boundary conditions.

Pang, Gen-Di, e Fu-Cho Pu. "Non-linear optical effects in quasi-periodic multi-layered media". Journal of Physics C: Solid State Physics 21, n. 22 (10 agosto 1988): L853—L856. http://dx.doi.org/10.1088/0022-3719/21/22/014.

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Ben-Messaoud, Tahar, Jason Riordon, Alexandre Melanson, P. V. Ashrit e Alain Haché. "Photoactive periodic media". Applied Physics Letters 94, n. 11 (16 marzo 2009): 111904. http://dx.doi.org/10.1063/1.3095478.

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Più fonti

Tesi sul tema "Periodic and quasi-Periodic media":

Amenoagbadji, Pierre. "Wave propagation in quasi-periodic media". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAE020.

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L'objectif de la thèse est de développer des méthodes numériques originales pour la résolution de l'équation des ondes en régime harmonique dans des milieux quasi-périodiques, dans l'esprit des méthodes développées précédemment pour des milieux périodiques. L'idée est d'utiliser comme dans des travaux d'homogénéisation quasi-périodique le fait que l'étude d'une EDP elliptique avec des coefficients quasi-périodiques se ramène à l'étude d'une EDP elliptiquement dégénérée en dimension supérieure, mais dont les coefficients sont périodiques. Le caractère périodique permet d'utiliser des outils adaptés, mais le caractère non-elliptique rend toutefois l'analyse mathématique et numérique de l'EDP délicate. Une des applications étudiées dans ce manuscrit concerne des problèmes de transmission entre des demi-plans périodiques (typiquement des cristaux photoniques) quand (1) l'interface ne coupe pas les demi-plans périodiques dans une direction de périodicité, ou (2) quand les milieux périodiques n'ont pas des périodes commensurables le long de l'interface
The goal of this thesis is to develop efficient numerical methods for the solution of the time-harmonic wave equation in quasiperiodic media, in the spirit of methods previously developed for periodic media. The goal is to use as in quasiperiodic homogenization the idea that an elliptic PDE with quasiperiodic coefficients can be interpreted as the cut of a higher-dimensional PDE which is elliptically degenerate, but with periodic coefficients. The periodicity property allows to use adapted tools, but the non-elliptic aspect makes the mathematical and numerical analysis of the PDE delicate. One application concerns transmission problems between periodic half-spaces (typically photonic crystals) when (1) the interface does not cut the periodic half-spaces in a direction of periodicity, or (2) when the periodic media have noncommensurate periods along the interface

Chalmers, Luke. "Locally resonant periodic acoustic media". Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7120.

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Phononic crystals are composite media, with two different elastic materials modulated in a periodic fashion. The two-dimensional system under study is comprised of an array of cylindrical tubes arranged in a square Bravais lattice. The propagation of a time-harmonic acoustic Bloch waves is investigated experimentally and the findings compared with those obtained from the finite element method. The band structure, that is a well-known characteristic of Bloch wave dispersion, is also determined. This demonstrates the existence of band gaps of forbidden transmission at certain frequency ranges. These arise due to the interference when the wavelength of the incident wave is comparable to the periodic spacing of the modulated media. A second phononic crystal with slotted steel tubes is also studied. The opening in the tube permitting air to flow to the internal cavity, and constituting a Helmholtz resonator. The band structure of such a structure possesses additional band gaps, which arise due to the excitation of the resonators. Furthermore, it has recently been shown that periodically distributed Helmholtz resonator structures, can exhibit negative refraction phenomena. Using the transmission line technique, as outlined by Y.Cheng et al. we demonstrate this behaviour for our experimental system. It is shown that, at certain frequency ranges, the locally resonant phononic crystal exhibits negative effective density and bulk modulus, the two conditions required to obtain a negative index of refraction.

Nassar, Hussein. "Elastodynamic homogenization of periodic media". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1151/document.

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La problématique récente de la conception de métamatériaux a renouvelé l'intérêt dans les théories de l'homogénéisation en régime dynamique. En particulier, la théorie de l'homogénéisation élastodynamique initiée par J.R. Willis a reçu une attention particulière suite à des travaux sur l'invisibilité élastique. La présente thèse reformule la théorie de Willis dans le cas des milieux périodiques, examine ses implications et évalue sa pertinence physique au sens de quelques ``conditions d'homogénéisabilité'' qui sont suggérées. En se basant sur les résultats de cette première partie, des développements asymptotiques approximatifs de la théorie de Willis sont explorés en relation avec les théories à gradient. Une condition nécessaire de convergence montre alors que toutes les branches optiques de la courbe de dispersion sont omises quand des développements asymptotiques de Taylor de basse fréquence et de longue longueur d'onde sont déployés. Enfin, une nouvelle théorie de l'homogénéisation est proposée. On montre qu'elle généralise la théorie de Willis et qu'elle l'améliore en moyenne fréquence de sorte qu'on retrouve certaines branches optiques omises auparavant. On montre également que le milieu homogène effectif défini par la nouvelle théorie est un milieu généralisé dont les champs satisfont une version élastodynamique généralisée du lemme de Hill-Mandel
The recent issue of metamaterials design has renewed the interest in homogenization theories under dynamic loadings. In particular, the elastodynamic homogenization theory initiated by J.R. Willis has gained special attention while studying elastic cloaking. The present thesis reformulates Willis theory for periodic media, investigates its outcome and assesses its physical suitability in the sense of a few suggested ``homogenizability conditions''. Based on the results of this first part, approximate asymptotic expansions of Willis theory are explored in connection with strain-gradient media. A necessary convergence condition then shows that all optical dispersion branches are lost when long-wavelength low-frequency Taylor asymptotic expansions are carried out. Finally, a new homogenization theory is proposed to generalize Willis theory and improve it at finite frequencies in such a way that selected optical branches, formerly lost, are recovered. It is also proven that the outcome of the new theory is an effective homogeneous generalized continuum satisfying a generalized elastodynamic version of Hill-Mandel lemma

Powell, Sean K. "A quantitative study of diffusion in quasi-periodic fibre networks and complex porous media". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/92506/12/92506%28thesis%29.pdf.

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Diffusion is the fundamental process behind many molecular phenomena such as the mixing of substances. Its physical basis is the random motion of particles in a fluid. In complex porous media, diffusion is restricted by interactions with internal structures. In this work, we present studies of restricted diffusion that aim to efficiently produce quantitative models for obtaining detailed information about the morphology of biological porous media from diffusion tensor imaging experiments. We achieved this by developing a Langevin dynamics algorithm to provide physically realistic modelling of water/barrier interactions and the Lattice-Path Count algorithm to enumerate all available particle trajectories to evaluate molecular transport properties. We also performed diffusion tensor imaging experiments of the fibre networks of tissue engineering scaffolds. The findings of this thesis provide further insight into the physics underlying restricted diffusion.

Nixon, Grant Ian. "Entropic trapping and polymer dynamics in static, quasi-periodic arrays of obstacles in two dimensional media". Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26307.

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Using the bond fluctuation algorithm of Carmesin and Kremer (Carmesin and Kremer 1988), we investigate the static and dynamic properties of self-avoiding linear polymers embedded in static, two-dimensional (d=2), quasi-periodic arrays of obstacles with entropic traps. The phenomenon of polymer collapse, the closely related enrichment and depletion of polymer configurations, the conformational relaxation, and the diffusive behaviour are all investigated within the framework of the lattice Monte Carlo method. Several distinct dynamical regimes are encountered: the (obstacle-free) Rouse-like regime (obstacle sub-array concentration c=0), the reptation regime for chains in perfectly periodic obstacle sub-arrays (c=1), and, in the presence of disorder and entropic traps (0<c<1), the anomalous regimes where the scaling properties differ from those predicted by the Rouse and reptation theories. Prior to the onset of normal diffusion, even systems characterized by very slight disorder (i.e., the existence of random isolated void spaces) are shown to lead to long, transient, subdiffusive regimes where the mean square displacement of the centre of mass scales as RCM 2∼D*tbeta where 0.5<beta<1 is the anomalous diffusion exponent and D* is the anomalous diffusion coefficient. In such disordered systems, conformational relaxation is shown to be coupled with centre of mass subdiffusion, resulting in long, time-stretched, exponential relaxation of the Rouse coordinates, viz. exp.[-(t/tau) alpha]. The stretching exponents 0.5<alpha<1 are shown to be closely related to the anomalous diffusion exponents beta and where the alpha, for a given chain, are shown to decrease with increasing mode number and with strong disorder. The molecular size-dependence of the steady-state diffusion coefficient, as well as that of the conformational relaxation time, is shown to be greatest when the concentration of obstacles is large and when that of the voids is non-vanishing (c ≲ 1). Thus, the dynamical scaling in entropic trapping systems is non-monotonic with respect to the concentration of obstacles. Polymer reptation dynamics thus appears to be intrinsically unstable with respect to static disordered systems of obstacles. Having demonstrated the coupling of centre of mass subdiffusion and conformational relaxation, we introduce a new relaxation length scale, lambda=(2dD*t alpha)1/2, that is more appropriate for characterizing disordered systems than is the ubiquitous radius of gyration used in both the Rouse and reptation theories. However, lambda could not be distinguished from the radius of gyration in terms of the molecular size scaling given the uncertainty in our data. Finally, having proposed a theoretical dynamic model of entropic trapping for dilute polymer solutions in embedded mesoscopic voids, we investigate the effect of polymer solution concentration on the dynamics for both monodisperse and polydisperse polymer solutions. New, unexplored dynamical behaviours are manifest as the conformational and translational entropies compete to minimize the system free energy.

Vanel, Alice. "Asymptotic analysis of discrete and continuous periodic media". Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/64911.

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Mechanical mass-spring networks have long acted to motivate, and gain qualitative intuition, in solid-state physics, continuous media containing periodic arrays of inclu- sions such as phononic crystals, and more recently in metamaterials. While in some cases an exact or approximate analogy between the continuous model and its discrete representation can be systematically drawn, more often such analogies are introduced heuristically to aid interpretation with the lumped parameters estimated and accepted as qualitative. This thesis builds towards making the analogy exact; we first look at the discrete masses and springs lattices and apply multiple-scales methods directly to Green’s function integrals to extract the behaviour near critical frequencies. The features we uncover, and the asymptotics, are generic for many lattice structures. We then identify and study a new class of materials, two- and three- dimensional phononic crystals formed by closely spaced rigid cylinders or interconnected perforated boxes, respectively, and show that such materials constitute a versatile and tuneable family of subwavelength metamaterials. Intuitively, the voids and narrow gaps that characterise the crystals form an interconnected network of Helmholtz-like resonators. We use this intuition to argue that these continuous phononic crystals are in fact asymptotically equivalent, at low frequencies, to discrete mass-spring networks whose lumped param- eters we derive explicitly. The crystals are tantamount to metamaterials as their entire acoustic branch is squeezed into a subwavelength regime where the ratio of wavelength to period scales like the ratio of period to gap width raised to the power 1/4 in two dimensions and 1/2 in three dimensions; at yet larger wavelengths we accordingly find a comparably large effective refractive index. The fully analytical dispersion relations predicted by the discrete models yield dispersion curves that agree with those from finite-element simulations of the continuous crystals.

Pathak, Mihir Gaurang. "Periodic flow physics in porous media of regenerative cryocoolers". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49056.

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Pulse tube cryocoolers (PTC) are a class of rugged and high-endurance refrigeration systems that operate without moving parts at their low temperature ends, and are capable of reaching temperatures down to and below 123 K. PTCs are particularly suitable for applications in space, guiding systems, cryosurgery, medicine preservation, superconducting electronics, magnetic resonance imaging, weather observation, and liquefaction of gases. Applications of these cryocoolers span across many industries including defense, aerospace, biomedical, energy, and high tech. Among the challenges facing the PTC research community is the improvement of system efficiency, which is a direct function of the regenerator component performance. A PTC implements the theory of oscillatory compression and expansion of the gas within a closed volume to achieve desired refrigeration. An important deficiency with respect to the state of art models dealing with PTCs is the limited understanding of the hydrodynamic and thermal transport parameters associated with periodic flow of a cryogenic fluid in micro-porous structures. In view of the above, the goals of this investigation include: 1) experimentally measuring and correlating the steady and periodic flow Darcy permeability and Forchheimer’s inertial hydrodynamic parameters for available rare-Earth ErPr regenerator filler; 2) employing a CFD-assisted methodology for the unambiguous quantification of the Darcy permeability and Forchheimer’s inertial hydrodynamic parameters, based on experimentally measured steady and periodic flow pressure drops in porous structures representing recently developed regenerator fillers; and 3) performing a direct numerical pore-level investigation for steady and periodic flows in a generic porous medium in order to elucidate the flow and transport processes, and quantify the solid-fluid hydrodynamic and heat transfer parameters. These hydrodynamic resistances parameters were found to be significantly different for steady and oscillatory flows.

Nitsche, Ludwig C. (Ludwig Carlos). "Multiphase flow through spatially periodic models of porous media". Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/111043.

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Mantel, Rolf-Martin. "Periodic forcing and symmetry breaking of waves in excitable media". Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263610.

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Mehrem, Issa Mohamed Mehrem Ahmed. "Nonlinear acoustics in periodic media: from fundamental effects to applications". Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/80289.

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The natural dynamics are not ideal or linear. To understand their complex behavior, we needs to study the nonlinear dynamics in more simple models. This thesis is consist of two main setups. Both setups are simplified models for the behavior occurs in the complex systems. We studied in both systems the same nonlinear dynamics such as higher-harmonics, sub-harmonics, solitary waves,...etc. In Chapter (2), the propagation of nonlinear waves in a lattice of repelling particles is studied theoretically and experimentally. A simple experimental setup is proposed, consisting in an array of coupled magnetic dipoles. By driving harmonically the lattice at one boundary, we excite propagating waves and demonstrate different regimes of mode conversion into higher harmonics, strongly in influenced by dispersion. The phenomenon of acoustic dilatation of the chain is also predicted and discussed. The results are compared with the theoretical predictions of FPU equation, describing a chain of masses connected by nonlinear quadratic springs. The results can be extrapolated to other systems described by this equation. We studied theoretically and experimentally the generation and propagation of kinks in the system. We excite pulses at one boundary of the system and demonstrate the existence of kinks, whose properties are in very good agreement with the theoretical predictions, that is the equation that approaches, under the conditions of our experiments, the one corresponding to full model describing a chain of masses connected by magnetic forces. The results can be extrapolated to other systems described by this equation. Also, In the case of a lattice of finite length, where standing waves are formed, we report the observation of subharmonics of the driving wave. In chapter (3), we studied the propagation of intense acoustic waves in a multilayer crystal. The medium consists in a structured fluid, formed by a periodic array of fluid layerswith alternating linear acoustic properties and quadratic nonlinearity coefficient. We presents the results for different mathematicalmodels (NonlinearWave Equation,Westervelt Equation and Constitutive equations). We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media. In chapter (4), the oscillatory behavior of a microbubble is investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between 1 and 5 Hz is considered. Simulations have been carried out and show spatial mode, mixing and localization phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to investigate the complexity of microbubble dynamics.
La dinámica natural no es ideal ni lineal. Para entender su comportamiento complejo, necesitamos estudiar la dinámica no lineal en modelos más simples. Esta tesis consta de dos configuraciones principales. Ambas configuraciones son modelos simplificados de el comportamiento que se produce en los sistemas complejos. Estudiamos en ambos sistemas la misma dinámica no lineal como son la generación de armónicos superiores, los sub-armónicos, las ondas solitarias, etc. En elCapítulo (2), se estudia, tanto teórica comoexperimentalmente, la propagación de ondas no lineales en sistemas periodicos de partículas acopladas mediante fuerzas repulsivas. Se propone una configuración experimental simple, que consiste en una matriz de dipolos magnéticos acoplados. Inyectando armónicamente la señal en un extremo, excitamos ondas de propagación y demostramos diferentes regímenes de conversión de modos en armónicos, fuertemente influenciados por la dispersión. También se predice y se discute el fenómeno de dilatación acústica de la cadena. Los resultados se comparan con las predicciones teóricas de la ecuación FPU, describiendo una cadena de masas conectadas por muelles cuadráticos no lineales. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Estudiamos también teórica y experimentalmente la generación y propagación de kinks. Excitamos pulsos en la frontera del sistema y demostramos la existencia de kinks cuyas propiedades están en muy buen acuerdo con las predicciones teóricas, es decir, con la ecuación que aproxima bajo las condiciones de nuestros experimentos la correspondiente al modelo completo que describe un cadena de masas conectadas por fuerzas magnéticas. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Además, en el caso de una red finita, donde se forman ondas estacionarias, describimos la observación de subarmónicos del armónico principal. En el capítulo (3), estudiamos la propagación de ondas acústicas intensas en un cristal multicapa. El medio consiste en un fluido estructurado, formado por un conjunto periódico de capas fluidas con propiedades acústicas lineales alternas y coeficiente de no linealidad cuadrática. Presentamos los resultados de diferentes modelos matemáticos (ecuación de ondas no lineal, ecuación de Westervelt y ecuaciones constitutivas). Mostramos que la interacción entre la fuerte dispersión y la no linealidad conduce a nuevos escenarios de propagaciónde ondas. El proceso de distorsión de la onda clásica, típico de las ondas acústicas intensas en medios homogéneos, puede ser alterado de forma importante cuando los armónicos generados no linealmente se encuentran dentro o cerca del gap. Esto permite la posibilidad de diseñar un medio con el fin de obtener una forma de onda en particular. Ejemplos de esto incluyen el diseño demedios con no linealidad efectiva (por ejemplo, cúbica) o medios extremadamente lineales. En el capítulo (4), el comportamiento oscilatorio de una microburbuja se investiga a través de una analogía acusto-mecánica basada en una cadena en forma de anillo de péndulos acoplados. Se estudian los modos de vibración paramétrica del anillo pendular excitado a frecuencias entre 1 y 5 Hz. Se han llevado a cabo simulaciones que muestran la presencia de modos espaciales, mixtos y fenómenos de localización. Se discute la relevancia de la analogía entre una microburbuja y la configuración macroscópica acústico-mecánica y se sugiere como una vía alternativa para investigar la complejidad de la dinàmica de microburbujas.
La dinàmica natural no és ideal ni tampoc lineal. Per entendre el seu comportament complex, es necessita estudiar la dinàmica no lineal dels models més simples. Aquesta tesi consisteix en l'estudi de dues configuracions principals, que són models simplificats del comportament que es produeix en els sistemes complexos. Estudiem en ambdós sistemes la mateixa dinàmica no lineal, com és la generació d'harmònics superiors, sub-harmònics, ones solitàries, etc. En el capítol (2), estudiem, tant teòrica com experimentalment, la propagació de les ones no lineals en sistemes periòdics de partícules acoblades mitjançant forces repulsives. Es proposa una configuració experimental simple, que consisteixen en una matriu de dipols magnètics acoblats. En conduint harmònicament la xarxa en un límit, excitemla propagació de les ones i demostrem diferents règims de conversió de modes en harmònics més alts, força influenciada per la dispersió. El fenomen de la dilatació acústica de la cadena també es prediu i es discuteix. Els resultats es comparen amb les prediccions teòriques que descriu una cadena de masses conectades per molls quadràtics no lineals. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. Hem estudiat teòrica i experimentalment la generació i propagació de Kinks. Excitem polsos a la frontera del sistema i demostrem l'existència d'Kinks, les propietats desl quals estan en molt bon acord amb les prediccions teòriques, és a dir, de l'equació que aproxima sota les condicions dels nostres experiments la corresponent al model complet que descriu un cadena demasses connectades per forcesmagnètiques. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. A més, en el cas d'una xarxa finita, on es formen ones estacionàries, descrivim l'observació de subarmónicos de l'harmònic principal. En el capítol (3), s'estudia la propagació d'ones acústiques intenses en un medi multicapa. El medi consisteix en un fluid estructurat, format per una matriu periòdica de capes de fluid amb l'alternança de propietats acústiques lineals i coeficient de no linealitat de segon grau. Es presenten els resultats per a diferents models matemàtics no lineals (equació d'ones no lineal, equació de Westervelt i les equacions constitutives). Es demostra que la interacciò entre la forta dispersió i no linealitat condueix a nous escenaris de propagació de l'ona. El procés de distorsió en formad'ona clàssica, típica de les ones acústiques intenses en medis homogenis, es pot alterar de manera significativa quan els harmònics generats de forma no lineal es troben dins o a prop del gap. Això obri la possibilitat de dissenyar unmedi per tal d'obtenir una forma d'ona particular. Exemples d'això inclouen el disseny delsmedis amb una no linealitat efectiva (per exemple cúbica), o medis extremadament lineals. En el capítol (4), el comportament oscilatori d'una micro-bombolla és investigat a través d' una analogia acústica-mecànica basada en una cadena en forma d'anell de pèndols acoblats. Es considera l'observació dels modes de vibració paramètriques de l'anell pendular excitat amb freqüències entre 1 i 5 Hz. S'han dut a terme simulacions que mostren la presència de moes espacilas, mixtes i fenòmens de localització. Es discuteix la relevància de l'analogia entre les microbambolles i la configuració macroscòpica acústica-mecànica i es suggereix una formaalternativa per a investigar la complexitat de la dinàmica demicrobombolles.
Mehrem Issa Mohamed Mehrem, A. (2017). Nonlinear acoustics in periodic media: from fundamental effects to applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80289
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Libri sul tema "Periodic and quasi-Periodic media":

Kuchment, Peter, a cura di. Waves in Periodic and Random Media. Providence, Rhode Island: American Mathematical Society, 2003. http://dx.doi.org/10.1090/conm/339.

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Bakhvalov, N., e G. Panasenko. Homogenisation: Averaging Processes in Periodic Media. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2247-1.

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Belyakov, Vladimir. Diffraction Optics of Complex-Structured Periodic Media. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-43482-7.

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Belyakov, Vladimir Alekseevich. Diffraction Optics of Complex-Structured Periodic Media. New York, NY: Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-4396-0.

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Belyakov, Vladimir Alekseevich. Diffraction Optics of Complex-Structured Periodic Media. New York, NY: Springer New York, 1992.

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Beli͡akov, V. A. Diffraction optics of complex-structured periodic media. New York: Springer-Verlag, 1992.

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Romeo, Francesco, e Massimo Ruzzene, a cura di. Wave Propagation in Linear and Nonlinear Periodic Media. Vienna: Springer Vienna, 2012. http://dx.doi.org/10.1007/978-3-7091-1309-7.

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Jiménez, Noé, Olga Umnova e Jean-Philippe Groby, a cura di. Acoustic Waves in Periodic Structures, Metamaterials, and Porous Media. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-84300-7.

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Nevière, M. Light propagation in periodic media: Differential theory and design. New York: Marcel Dekker, 2003.

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Mantel, Rolf-Martin. Periodic forcing and symmetry breaking of waves in excitable media. [s.l.]: typescript, 1997.

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Capitoli di libri sul tema "Periodic and quasi-Periodic media":

Lukš, Antonín, e Vlasta Perinová. "Periodic and Disordered Media". In Quantum Aspects of Light Propagation, 321–451. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b101766_6.

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Xin, Jack. "Fronts in Periodic Media". In An Introduction to Fronts in Random Media, 23–51. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-0-387-87683-2_2.

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McGurn, Arthur. "Properties of Periodic Media". In An Introduction to Condensed Matter Physics for the Nanosciences, 89–135. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003031987-4.

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Banerjee, Sourav. "Waves in Periodic Media". In Metamaterials in Topological Acoustics, 229–352. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003225751-6.

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Belyakov, Vladimir. "Nonlinear Optics of Periodic Media". In Diffraction Optics of Complex-Structured Periodic Media, 97–121. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-43482-7_4.

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Belyakov, Vladimir Alekseevich. "Nonlinear Optics of Periodic Media". In Partially Ordered Systems, 188–214. New York, NY: Springer New York, 1992. http://dx.doi.org/10.1007/978-1-4612-4396-0_6.

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Jänicke, Ralf, e Stefan Diebels. "Requirements on Periodic Micromorphic Media". In Advances in Mechanics and Mathematics, 99–107. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-5695-8_11.

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Vakakis, Alexander F. "Methodologies for Nonlinear Periodic Media". In Wave Propagation in Linear and Nonlinear Periodic Media, 257–326. Vienna: Springer Vienna, 2012. http://dx.doi.org/10.1007/978-3-7091-1309-7_5.

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Quadrelli, Davide Enrico, e Francesco Braghin. "Wave Propagation in Periodic Media". In Acoustic Invisibility for Elliptic Objects, 11–37. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-22603-8_2.

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Allali, K., e M. Belhaq. "Influence of Periodic and Quasi-periodic Gravitational Modulation on Convective Instability of Reaction Fronts in Porous Media". In Understanding Complex Systems, 71–93. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-34070-3_14.

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Atti di convegni sul tema "Periodic and quasi-Periodic media":

Skipetrov, S. E., N. Cherroret e B. A. van Tiggelen. "Anderson Localization in Open Random Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/meta.2007.mb2.

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Bertolotti, Jacopo, R. Sapienza, P. D. Garcia, C. Lopez e D. S. Wiersma. "Coherent backscattering from resonant disordered media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/meta.2007.tub13.

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van Tiggelen, B. A., e G. L. J. A. Rikken. "Zero-Point Momentum in Complex Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/meta.2007.wc2.

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Lagendijk, Ad. "The Path of Light in Random Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/meta.2006.mb1.

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Carminati, R., R. Pierrat e J. J. Greffet. "Photon diffusion coefficient in absorbing random media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/meta.2006.thb2.

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Chowdhury, Aref, Marjan Saboktakin e John A. Tataronis. "Four-Wave Mixing in Negative Refractive Index Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/meta.2007.tub3.

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Froufe-Pérez, L. S., R. Pierrat, J. J. Sáenz e R. Carminati. "Statistical Properties of Single Molecule Fluorescence in Disordered Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/meta.2007.tub26.

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Skipetrov, S. E., e B. A. van Tiggelen. "Self-consistent theory of Anderson localization in open random media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/meta.2006.mb5.

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Lagendijk, Ad. "Wrap Up of The Path of Light in Random Media". In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/meta.2006.the2.

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Narimanov, Evgenii, e Leonid Alekseyev. "Optical “Hyperspace”: Negative Refractive Index and Subwavelength Imaging in Anisotropic Media." In Photonic Metamaterials: From Random to Periodic. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/meta.2006.tuc2.

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Rapporti di organizzazioni sul tema "Periodic and quasi-Periodic media":

Figotin, Alex. Spectral Properties of Periodic and Disordered Dielectric and Acoustic Media. Fort Belvoir, VA: Defense Technical Information Center, dicembre 1998. http://dx.doi.org/10.21236/ada360464.

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Vold, E. L. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations. Office of Scientific and Technical Information (OSTI), marzo 1997. http://dx.doi.org/10.2172/444057.

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Sasaki, Shigemi. Concept of quasi-periodic undulator - control of radiation spectrum. Office of Scientific and Technical Information (OSTI), febbraio 1995. http://dx.doi.org/10.2172/88773.

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Musardo, Marco. Magnetic Tuning of a Quasi-Periodic Elliptically Polarized Undulator. Office of Scientific and Technical Information (OSTI), ottobre 2017. http://dx.doi.org/10.2172/1569011.

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Sherman, Peter J. Stochastic Characterizations for Signals & Systems Associated with Quasi-Periodic Systems. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2001. http://dx.doi.org/10.21236/ada398780.

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Neuffer, D., e E. Forest. A general formalism for quasi-local correction of multipole distortions in periodic transport systems. Office of Scientific and Technical Information (OSTI), giugno 1988. http://dx.doi.org/10.2172/6215770.

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Schuster, Christian. Strategies to Professionalize the Civil Service: Lessons from the Dominican Republic. Inter-American Development Bank, settembre 2014. http://dx.doi.org/10.18235/0010594.

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Abstract (sommario):

Drawing on a case study of recent reforms in the Dominican Republic, this technical note derives lessons about strategies to professionalize the civil service. As in other countries with less professionalized civil services, the Dominican Republic's political economy is biased against reform: promises of public employment tend to be important to successful electoral mobilization. Nonetheless, passage of a new public service law and its partial implementation were achieved. The case study finds that the construction of a broad societal coalition demanding reform may account for this puzzle. For legislative approval, alliance formation extended to not only traditional reform allies, such as the international community, NGOs, business associations, the media, progressive governing legislators and a politically influential minister, but also novel allies, including opposition parties. Reform implementation was fostered by the periodic and well-publicized societal monitoring of an achievable set of reform objectives aligned with the strategic priorities of the Ministry of Public Administration. As a result, political incentives were tilted towards legal reform passage and incremental compliance in civil service subsystems such as organizational structures, information systems and training not perceived as threatening to core electoral mobilization interests, yet not in more politically contentious subsystems, such as recruitment and selection. The case study underscores the desirability of constructing broad societal coalitions to enable civil service professionalization particularly in contexts where potential societal veto actors with vested interests, such as public sector unions, are largely absent. It also underscores the continued weight of political economy constraints in conditioning the subsystems in which civil service reform implementation may be achieved.

Chen, Z., e S. E. Grasby. Temporal trend analysis of synthetic and real hydroclimate time series and impacts of long term quasi-periodic components on trend tests. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2009. http://dx.doi.org/10.4095/247832.

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Kadlec, Amanda. Still Kicking: the Survivability of the Islamic State in Libya. RESOLVE Network, dicembre 2020. http://dx.doi.org/10.37805/pn2020.10.ssa.

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Abstract (sommario):

Since emerging in eastern Libya in 2014, ISIS laid claim to wilayat within Libya’s three regional provinces—Tripolitania, Barqa, and Fezzan—moving fast to establish a quasi-state in the coastal city of Sirte and amassing just a few thousand fighters at its peak strength. Yet, just as ISIS core’s territorial hold in Syria and Iraq withered, its strength in Libya also soon diminished. Sustained domestic and international counterterrorism efforts have severely depleted ISIS in Libya’s (ISIS-L) numbers, operational capacity, and opportunity for safe haven. However, while weakened, ISIS-L’s survivability is driven by a far more complex range of factors than just Libya’s domestic unrest. The apex of ISIS-L’s power from 2014 to 2016 may have been brief, and its current threat low, but the group’s damage to Libya lingers, and the potential for its continued periodic revival should not be understated. For those seeking to counter and address ISIS-L’s continued presence in Libya, understanding the factors that simultaneously facilitate and hamper the group’s operations and growth is paramount to crafting appropriate interventions.