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Dissertations / Theses on the topic 'Asymptotic expansions of solutions'

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Published: 4 June 2021
Last updated: 3 February 2022

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1

Xiaochun, Liu, and Ingo Witt. "Asymptotic expansions for bounded solutions to semilinear Fuchsian equations." Universität Potsdam, 2001. http://opus.kobv.de/ubp/volltexte/2008/2591/.

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It is shown that bounded solutions to semilinear elliptic Fuchsian equations obey complete asymptoic expansions in terms of powers and logarithms in the distance to the boundary. For that purpose, Schuze's notion of asymptotic type for conormal asymptotics close to a conical point is refined. This in turn allows to perform explicit calculations on asymptotic types - modulo the resolution of the spectral problem for determining the singular exponents in the asmptotic expansions.
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2

Höppner, Reinhard Höppner Reinhard Höppner Reinhard. "Asymptotic and hyperasymptotic expansions of solutions of linear differential equations near irregular singular points of higher rank." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962883921.

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Hoeppner, Reinhard. "Asymptotic and hyperasymptotic expansions of solutions of linear differential equations near irregular singular points of higher rank." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962883921.

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4

Hoang, Luan Thach. "Asymptotic expansions of the regular solutions to the 3D Navier-Stokes equations and applications to the analysis of the helicity." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2355.

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A new construction of regular solutions to the three dimensional Navier{Stokes equa- tions is introduced and applied to the study of their asymptotic expansions. This construction and other Phragmen-Linderl??of type estimates are used to establish su??- cient conditions for the convergence of those expansions. The construction also de??nes a system of inhomogeneous di??erential equations, called the extended Navier{Stokes equations, which turns out to have global solutions in suitably constructed normed spaces. Moreover, in these spaces, the normal form of the Navier{Stokes equations associated with the terms of the asymptotic expansions is a well-behaved in??nite system of di??erential equations. An application of those asymptotic expansions of regular solutions is the analysis of the helicity for large times. The dichotomy of the helicity's asymptotic behavior is then established. Furthermore, the relations between the helicity and the energy in several cases are described.
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5

Masaki, Satoshi. "Asymptotic expansion of solutions to the nonlinear Schrödinger equation with power nonlinearity." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124383.

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6

Starkloff, Hans-Jörg, and Ralf Wunderlich. "Stationary solutions of linear ODEs with a randomly perturbed system matrix and additive noise." Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200501335.

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The paper considers systems of linear first-order ODEs with a randomly perturbed system matrix and stationary additive noise. For the description of the long-term behavior of such systems it is necessary to study their stationary solutions. We deal with conditions for the existence of stationary solutions as well as with their representations and the computation of their moment functions. Assuming small perturbations of the system matrix we apply perturbation techniques to find series representations of the stationary solutions and give asymptotic expansions for their first- and second-order moment functions. We illustrate the findings with a numerical example of a scalar ODE, for which the moment functions of the stationary solution still can be computed explicitly. This allows the assessment of the goodness of the approximations found from the derived asymptotic expansions.
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7

Arazy, Jonathan, Bent Orsted, and jarazy@math haifa ac il. "Asymptotic Expansions of Berezin Transforms." ESI preprints, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi922.ps.

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8

Chapman, Frederick William. "Theory and applications of dual asymptotic expansions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0003/MQ32870.pdf.

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9

Kosad, Youssouf. "Analyse spectrale et comportement asymptotique des solutions de quelques modèles d’équations de transport." Thesis, Université Clermont Auvergne‎ (2017-2020), 2017. http://www.theses.fr/2017CLFAC056/document.

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Cette thèse est consacrée à la théorie spectrale de quelques opérateurs de transport et le comportement asymptotique (pour les temps grands) des solutions des problèmes de Cauchy gouvernés par ces derniers. Dans la première partie, on s'est intéressé aux propriétés spectrales des opérateurs d'advection et de transport des neutrons dans le cadre multidimensionnel pour des conditions aux limites générales. Après avoir établi un résultat de compacité de type lemmes de moyenne indispensable dans notre analyse, on a donné entre autre une description fine du spectre asymptotique de l'opérateur de transport. Ce travail a été complété par l'étude des propriétés de régularité et le comportement asymptotique de la solution du problème de Cauchy gouverné par l'opérateur de transport étudié précédemment pour des conditions aux limites de type bounce-back plus un opérateur compact dans l'espace L^1. Ensuite, on a étudié le caractère bien posé et le comportement asymptotique de la solution d'une équation de transport des neutrons avec des sections efficaces non bornées. Contrairement à la première partie, l'analyse de ce problème nécessite l'usage d'une théorie de perturbation de Miyadera-Voigt pour les opérateurs non bornés. La dernière partie de ce travail porte sur un problème linéaire issu d'un modèle introduit en 1974 par Lebowitz et Rubinow décrivant la prolifération d'une population de cellules structuré par l'âge et la longueur du cycle. Notre analyse a porté sur le cas où la longueur du cycle maximale est infinie
This thesis is devoted to the spectral theory and the time asymptotic behavior of the solution to Cauchy problems governed by various transport operators. In the first part, we discussed the spectral properties of streaming and transport operators in finite bodies with general boundary conditions. After establishing a compactness result essential to our analysis, we gave a fine description of the asymptotic spectrum of the transport operator. We also derive the regularity and the asymptotic behavior of the solution to Cauchy problem governed by the transport operator supplemented by bounce-back boundary conditions plus a compact operator in the space L^1. In the second part, we discussed the well-posedness and the asymptotic behavior of the solution to Cauchy problem governed by a singular transport operator. Unlike the first part, the analysis of this problem requires the use of Miyadera-Voigt perturbation theory for unbounded operators. In the last part of this work, a Cauchy problem governed by a linear operator introduced by Lebowitz and Rubinow describing a proliferating cell population structured by age and the cycle length was considered. Here our analysis was devoted to the case where the maximum cycle length is infinite
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Petersson, Mikael. "Asymptotic Expansions for Perturbed Discrete Time Renewal Equations." Licentiate thesis, Stockholms universitet, Matematiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-95490.

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In this thesis we study the asymptotic behaviour of the solution of a discrete time renewal equation depending on a small perturbation parameter. In particular, we construct asymptotic expansions for the solution of the renewal equation and related quantities. The results are applied to studies of quasi-stationary phenomena for regenerative processes and asymptotics of ruin probabilities for a discrete time analogue of the Cramér-Lundberg risk model.
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11

Chatterjee, Arindam. "Applications of asymptotic expansions to some statistical problems." [Ames, Iowa : Iowa State University], 2007.

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12

Strasser, Helmut. "Asymptotic expansions for conditional moments of Bernoulli trials." Oldenbourg Verlag, 2012. http://dx.doi.org/10.1524/strm.2012.1124.

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In this paper we study conditional distributions of independent, but not identically distributed Bernoulli random variables. The conditioning variable is the sum of the Bernoulli variables. We obtain Edgeworth expansions for the conditional expectations and the conditional variances and covariances. The results are of basic interest for several applications, e.g. for the study of conditional maximum likelihood estimation in Rasch models with many item parameters.
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Archalousová, Olga. "Singulární počáteční úloha pro obyčejné diferenciální a integrodiferenciální rovnice." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-233525.

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The thesis deals with qualitative properties of solutions of singular initial value problems for ordinary differential and integrodifferential equations which occur in the theory of linear and nonlinear electrical circuits and the theory of therminionic currents. The research is concentrated especially on questions of existence and uniqueness of solutions, asymptotic estimates of solutions and modications of Adomian decomposition method for singular initial problems. Solution algoritms are derived for scalar differential equations of Lane-Emden type using Taylor series and modication of the Adomian decomposition method. For certain classes of nonlinear of integrodifferential equations asymptotic expansions of solutions are constructed in a neighbourhood of a singular point. By means of the combination of Wazewski's topological method and Schauder xed-point theorem there are proved asymptotic estimates of solutions in a region which is homeomorphic to a cone having vertex coinciding with the initial point. Using Banach xed-point theorem the uniqueness of a solution of the singular initial value problem is proved for systems of integrodifferential equations of Volterra and Fredholm type including implicit systems. Moreover, conditions of continuous dependence of a solution on a parameter are determined. Obtained results are presented in illustrative examples.
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14

Elsawi, Mohamed Abdel Halim. "Asymptotic analysis of the spatial weights of the arbitrarily high order transport method." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3031048.

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15

Starkloff, Hans-Jörg. "Higher order asymptotic expansions for weakly correlated random functions." Doctoral thesis, Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200500122.

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Die vorliegende Arbeit beschäftigt sich mit asymptotischen Entwicklungen höherer Ordnung für zweite Momente von Zufallsvariablen bzw. Zufallsfunktionen, die als lineare Integralfunktionale über schwach abhängige oder schwach korrelierte Zufallsfunktionen definiert sind. Unter bestimmten Glattheits- und Integrabilitätsbedingungen an die Kernfunktionen und Regularitätsbedingungen an die Zufallsfunktionen werden entsprechende asymptotische Entwicklungen angegeben, außerdem wird auf Abschätzungen der Genauigkeit eingegangen. Die auftretenden Zufallsfunktionen sind dabei stationäre reell- oder vektorwertige Zufallsprozesse, bestimmte Klassen nichtstationärer Zufallsprozesse und homogene Zufallsfelder. Die Anwendungsmöglichkeit wird an einer Reihe von Beispielen aufgezeigt.
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16

Reshetenko, Anna [Verfasser]. "Asymptotic expansions in classical and free probability / Anna Reshetenko." Bielefeld : Universitätsbibliothek Bielefeld, 2014. http://d-nb.info/1050025326/34.

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17

Dew, N. "Asymptotic structure of Banach spaces." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270612.

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The notion of asymptotic structure of an infinite dimensional Banach space was introduced by Maurey, Milman and Tomczak-Jaegermann. The asymptotic structure consists of those finite dimensional spaces which can be found everywhere `at infinity'. These are defined as the spaces for which there is a winning strategy in a certain vector game. The above authors introduced the class of asymptotic $\ell_p$ spaces, which are the spaces having simplest possible asymptotic structure. Key examples of such spaces are Tsirelson's space and James' space. We prove some new properties of general asymptotic $\ell_p$ spaces and also compare the notion of asymptotic $\ell_2$ with other notions of asymptotic Hilbert space behaviour such as weak Hilbert and asymptotically Hilbertian. We study some properties of smooth functions defined on subsets of asymptotic $\ell_\infty$ spaces. Using these results we show that that an asymptotic $\ell_\infty$ space which has a suitably smooth norm is isomorphically polyhedral, and therefore admits an equivalent analytic norm. We give a sufficient condition for a generalized Orlicz space to be a stabilized asymptotic $\ell_\infty$ space, and hence obtain some new examples of asymptotic $\ell_\infty$ spaces. We also show that every generalized Orlicz space which is stabilized asymptotic $\ell_\infty$ is isomorphically polyhedral. In 1991 Gowers and Maurey constructed the first example of a space which did not contain an unconditional basic sequence. In fact their example had a stronger property, namely that it was hereditarily indecomposable. The space they constructed was `$\ell_1$-like' in the sense that for any $n$ successive vectors $x_1 < \ldots < x_n$, $\frac{1}{f(n)} \sum_{i=1}^n \| x_i \| \leq \| \sum_{i=1}^n x_i \| \leq \sum_{i=1}^n \| x_i \|,$ where $ f(n) = \log_2 (n+1) $. We present an adaptation of this construction to obtain, for each $ p \in (1, \infty)$, an hereditarily indecomposable Banach space, which is `$\ell_p$-like' in the sense described above. We give some sufficient conditions on the set of types, $\mathscr{T}(X)$, for a Banach space $X$ to contain almost isometric copies of $\ell_p$ (for some $p \in [1, \infty)$) or of $c_0$. These conditions involve compactness of certain subsets of $\mathscr{T}(X)$ in the strong topology. The proof of these results relies heavily on spreading model techniques. We give two examples of classes of spaces which satisfy these conditions. The first class of examples were introduced by Kalton, and have a structural property known as Property (M). The second class of examples are certain generalized Tsirelson spaces. We introduce the class of stopping time Banach spaces which generalize a space introduced by Rosenthal and first studied by Bang and Odell. We look at subspaces of these spaces which are generated by sequences of independent random variables and we show that they are isomorphic to (generalized) Orlicz spaces. We deduce also that every Orlicz space, $h_\phi$, embeds isomorphically in the stopping time Banach space of Rosenthal. We show also, by using a suitable independence condition, that stopping time Banach spaces also contain subspaces isomorphic to mixtures of Orlicz spaces.
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18

Bonnafé, Alain. "Topological asymptotic expansions for a class of quasilinear elliptic equations. Estimates and asymptotic expansions of condenser p-capacities. The anisotropic case of segments." Thesis, Toulouse, INSA, 2013. http://www.theses.fr/2013ISAT0017/document.

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La Partie I présente l’obtention du développement asymptotique topologique pour une classe d’équations elliptiques quasilinéaires. Un point central réside dans la possibilité de définir la variation de l’état direct à l’échelle 1 dans R^N. Après avoir défini un cadre fonctionnel approprié faisant intervenir les normes L^p et L^2, et avoir justifié la classe d’équations considérée, la méthode se poursuit par l’étude du comportement asymptotique de la solution du problème d’interface non linéaire dans R^N et par une mise en dualité appropriée des états direct et adjoint aux différentes étapes d’approximation.La Partie II traite d’estimations et de développements asymptotiques de p-capacités de condensateurs, dont l’obstacle est d’intérieur vide et de codimension > ou = 2. Après les résultats préliminaires, les condensateurs équidistants permettent de donner deux illustrations de l’anisotropie engendrée par un segment dans l’équation de p-Laplace, puis d’établir une minoration de la p-capacité N-dimensionnelle d’un segment, qui fait intervenir les p-capacités d’un point, respectivement en dimensions N et (N-1). Les condensateurs elliptiques permettent d’établir que le gradient topologique de la 2-capacité n’est pas un outil approprié pour distinguer les courbes des obstacles d’intérieur non vide en 2D
Part I deals with obtaining topological asymptotic expansions for a class of quasilinear elliptic equations. A key point lies in the ability to define the variation of the direct state at scale 1 in R^N. After setting up an appropriate functional framework involving both the L^p and the L^2 norms, and then justifying the chosen class of equations, the approach goes on with the study of the asymptotic behavior of the solution of the nonlinear interface problem in R^N and by setting up an adequate duality scheme between the direct and adjoint states at each step of approximation. Part II deals with estimates and asymptotic expansions of condenser p-capacities and focuses on obstacles with empty interiors and with codimensions > ou = 2. After preliminary results, equidistant condensers are introduced to point out the anisotropy caused by a segment in the p-Laplace equation, and to provide a lower bound to the N-dimensional condenser p-capacity of a segment, by means of the N-dimensional and of the (N-1)-dimensional condenser p-capacities of apoint. Introducing elliptical condensers, it turns out that the topological gradient of the 2-capacity is not an appropriate tool to separate curves and obstacles with nonempty interior in 2D
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19

Gassama, Edrissa. "A Model of the Dye-Sensitized Solar Cell: Solution Via Matched Asymptotic Expansion." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1408058509.

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20

Miravitllas, Mas Ramon. "Asymptotic expansions, resurgence and large order behaviour of quantum chromodynamics." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667932.

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En les teories quàntiques de camps, les prediccions numèriques d’observables físics només es poden calcular amb expansions pertorbatives en potències de les constants d'acoblament, els paràmetres que determinen la força de les interaccions entre camps. Mentre que l’èxit predictiu de la teoria quàntica de camps no es pot negar, aquests càlculs pertorbatius estan plens de divergències. D’una banda, els coeficients de l’expansió pertorbativa es calculen a partir d’integrals de loops que són divergents la majoria de les vegades. Algunes d’aquestes divergències estan associades a termes no físics que es poden sostreure. En altres casos, s’aplica un procés de renormalització per cancelar aquestes divergències, però això suposa l'elecció d’un conveni teòric (escala i esquema) de la qual els observables físics no poden dependre. D’altra banda, un cop les integrals de loops han sigut renormalitzades, l’expansió resultant encara suma a una resposta infinita per tots els valors no nuls de la constant d'acoblament. Això succeeix perquè els coeficients de l’expansió creixent factorialment amb l’ordre. Tot i així, aquestes expansions es poden entendre com expansions asimptòtiques, que codifiquen el comportament de l’observable en el límit quan la constant d'acoblament s’acosta a zero, i l’observable es pot aproximar truncant l’expansió a un terme òptim. Aquest segon tipus de divergència no está limitat, de fet, a la teoria quàntica de camps, sinó que pot apareixer en diferents contextos de les matemàtiques i la física: per exemple, en expansions pertorbatives dels valors propis de l’energia d’un sistema de la mecànica quàntica, o com a solucions formals d’una equació diferencial. A la part I d’aquesta tesi, l’objecte principal d’estudi és la constant d'acoblament forta i les expansions pertorbatives d’observables físics a la quàntica chromodinàmica. Primer, discitum breument com les divergències de loops d’un gluó propagant-se a l’espai amb correccions quàntiques poden ser absorbides dins de la constant d'acoblament forta durant el procés de renormalització. Aquest procés, no obstant, implica el cost d’introduir dependències en l’escala i l’esquema dins la constant d'acoblament, per tant, aquesta no és un observable físic de la teoria. Això motiva una redefinició de la constant d'acoblament tal que la seva dependència en l’esquema es redueix a un sol paràmetre. Després utilitzem aquesta redefinició de la constant d'acoblament en anàlisis fenomenològics d’observables físics associats a dispersions electró-positró, i a la desintegració del Higgs i del tau en hadrons. Demostrem que eleccions apropiades d’aquest paràmetre d’esquema pot donar lloc a millores substancials de les prediccions pertorbatives d’aquests observables. A la part II, discutim les divergències d’expansions asimptòtiques en el context d’integrals de camí. Convencionalment, el mètode de la sumació de Borel asigna una resposta finita a les expansions divergents. Tot i així, la suma de Borel podria no contenir tota la informació d’una funció, perquè a aquesta li poden faltar correccions exponencialment petites. Llavors considerem una petita variació de la sumació de Borel, on una transformada de Borel generalitzada (una transformada de Laplace inversa) és seguida d’una transformada de Laplace direccionals. Aquestes eines ens permet donar, potser, millors respostes a problemes típics de la sumació de Borel, com la pèrdua de les correccions exponencials i les ambigüitats de la sumació de Borel. A més, definim ressurgència com una connexió entre la discontinuïtat d’una funció i els coeficients de la seva expansió asimptòtica. A partir d’aquesta definició, podem reduir el problema de ressurgència a un problema de correccions exponencials perdudes en les expansions asimptòtiques i podem relacionar diferents formes d’entendre la ressurgència que es troben a la literatura.
For realistic quantum field theories, numerical predictions of physical observables can only be calculated from perturbative expansions in powers of the couplings, the parameters that determine the strength of the field interactions. While the predictive success of quantum field theory is undeniable, these perturbative computations are plagued with divergences. On one hand, the coefficients of the perturbative expansion are computed from loop integrals that are divergent most of the times. Some of these divergences are associated with unphysical terms that can be subtracted. In other cases, a renormalisation procedure is applied to cancel these divergences, but this entails a choice of theoretical conventions (scale and scheme) which physical observables cannot depend on. On the other hand, once the loop integrals have been renormalised, the resulting expansion still sums to an infinite answer for all non-vanishing values of the coupling. This is due to the fact that the coefficients of the expansion grow factorially with the order. Still, these expansions can be understood as asymptotic expansions, which encode the limiting behaviour of the observable for small coupling, and whose truncation to an optimal term yields numerical approximations of the observable. This second kind of divergence is in fact not limited to quantum field theories, but it may arise in different contexts of mathematics and physics: for instance, in perturbative approximations to the energy eigenvalues of a quantum mechanic system, or in formal solutions to differential equations. In part I of this dissertation, the main object of study is the strong coupling constant and the perturbative expansions of physical observables in quantum chromodynamics. First, we briefly discuss how the loop divergence of the quantum corrected gluon propagator can be absorbed inside the strong coupling constant during the renormalisation. This process, however, comes at the cost of introducing scale and scheme dependences into the coupling, therefore it is not a physical observable of the theory. This motivates a coupling redefinition whose scheme dependence is reduced to a single parameter. We then use this coupling redefinition in phenomenological analysis of physical observables associated to electron-positron scattering, and to Higgs and tau decays into hadrons. We demonstrate that appropriate choices of this scheme parameter can lead to substantial improvements in perturbative predictions of these observables. In part II, we discuss the divergence of asymptotic expansions in the context of path integrals. Conventionally, the method of Borel summation assigns a finite answer to the divergent expansion. Still, the Borel sum might not encode the full information of a function, because it misses exponentially small corrections. We then consider a slight variation of the conventional Borel summation, in which a generalised Borel transform (an inverse Laplace transform) is followed by a directional Laplace transform. These tools allow us to give perhaps better answers to typical problems in Borel summation: missing exponential corrections and ambiguities in the Borel summation. In addition, we define resurgence as a connection between the discontinuity of a function and the coefficients of its asymptotic expansion. From this definition, we can reduce resurgence to the problem of missing exponential corrections in asymptotic expansions and correlate different approaches to resurgence found in the literature.
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21

Navas, Palencia Guillermo. "High-precision computation of uniform asymptotic expansions for special functions." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/667810.

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In this dissertation, we investigate new methods to obtain uniform asymptotic expansions for the numerical evaluation of special functions to high-precision. We shall first present the theoretical and computational fundamental aspects required for the development and ultimately implementation of such methods. Applying some of these methods, we obtain efficient new convergent and uniform expansions for numerically evaluating the confluent hypergeometric functions and the Lerch transcendent at high-precision. In addition, we also investigate a new scheme of computation for the generalized exponential integral, obtaining on the fastest and most robust implementations in double-precision floating-point arithmetic. In this work, we aim to combine new developments in asymptotic analysis with fast and effective open-source implementations. These implementations are comparable and often faster than current open-source and commercial stateof-the-art software for the evaluation of special functions.
Esta tesis presenta nuevos métodos para obtener expansiones uniformes asintóticas, para la evaluación numérica de funciones especiales en alta precisión. En primer lugar, se introducen fundamentos teóricos y de carácter computacional necesarios para el desarrollado y posterior implementación de tales métodos. Aplicando varios de dichos métodos, se obtienen nuevas expansiones uniformes convergentes para la evaluación numérica de las funciones hipergeométricas confluentes y de la función transcendental de Lerch. Por otro lado, se estudian nuevos esquemas de computo para evaluar la integral exponencial generalizada, desarrollando una de las implementaciones más eficientes y robustas en aritmética de punto flotante de doble precisión. En este trabajo, se combinan nuevos desarrollos en análisis asintótico con implementaciones rigurosas, distribuidas en código abierto. Las implementaciones resultantes son comparables, y en ocasiones superiores, a las soluciones comerciales y de código abierto actuales, que representan el estado de la técnica en el campo de la evaluación de funciones especiales.
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22

Falck, Erik. "Asymptotic Expansions of Integrals and the Method of Steepest Descent." Thesis, Uppsala universitet, Analys och sannolikhetsteori, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-310938.

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23

Stey, George Carl. "Asymptotic expansion for the L¹ Norm of N-Fold convolutions." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1174537038.

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Melamed, Nahum. "Guidance law development for aeroassisted transfer vehicles using matched asymptotic expansions." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/13436.

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Mansoor, Muavia, and Nasir Iqbal. "p-adic Expansions of Solutions of Congruence Equations." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-21101.

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26

ADES, ROBERTO. "H2/HINF PROBLEM APPROXIMATED SOLUTIONS BY BASIS EXPANSIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7811@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Esta tese apresenta um estudo na área de controle robusto não paramétrico, mais precisamente relacionado ao Problema H2/Hinf. O Principal objetivo deste trabalho consiste no projeto de controladores por uma abordagem direta sobre o problema mencionado, baseada em método de Gallerkin. Dois métodos foram propostos, sendo denominados Expansão em Base Pré-Estabelecida (EBPE) e Expansão em Base Otimizada (EBO). Para a aplicação destes métodos, os controladores estabilizantes do sistema em estudo devem ser explicitados por intermédio da parametrização de Youla. Em seguida, uma nova parametrização é realizada a fim de colocar o problema resultante em um formato padrão, com a norma Hinf sob a forma do problema de Nehari. Um controlador calculado por EBO ou EBPE possui ordem previamente determinada, estabiliza internamente a planta, minimiza um funcional de desempenho e satisfaz a um nível pré- especificado de robustez em estabilidade. Em EBPE, uma base é escolhida para o espaço solução e o ajuste dos coeficientes de seus vetores é realizado minimizando o critério proposto. A vantagem deste método é resolver um problema de otimização convexo. Por outro lado, a escolha dos vetores que participarão da base truncada já estará definida, levando a uma solução com ordem superior àquela obtida por EBO e um mesmo nível de desempenho. No método EBO, as tarefas de escolha dos vetores que participarão da base e seus respectivos ajustes de coeficientes são realizados simultaneamente. Embora este problema seja não convexo, sua vantagem reside na possibilidade de encontrar soluções com ordens relativamente menores em comparação com aquelas por EBPE para um mesmo nível de desempenho. Adicionalmente, discute-se alguns resultados teóricos, onde a existência e a unicidade da solução do Problema H2/Hinf são demonstradas. Mostra-se também que a sequência de controladores calculados pelos métodos propostos, à medida que a ordem aumenta, converge para a solução ótima do problema original.
This thesis presents a study on the subject of robust and non parametrical control, more precisely related to the Mixed H2/Hinf problem. The main purpose of this work consists in the controllers design by a direct approach over the mentioned problem, using Galerkin`s method. Two numerical methods were proposed, being known as Pre- Established Basis Expansion (EBPE) and Optimized Basis Expansion (EBO). For the application of these methods, the stabilizing controllers of the system under analisys must be explicated by Youla`s parametrization. After this, a new parametrization is performed in order to set the problem in a standard format, with the Hinf-norm in the Nehari problem. A controller computed by EBO or EBPE has a previously specified order, internally stabilizes the plant, minimizes a performance functional and satisfies a pre- established robustness stability margin. In the EBPE method, a basis is chosen from space solution and the adjustment of the vectors` coefficients is performed minimizing the proposed criterion. The advantage is solve a convex optimization problem. By the other side, the choice of vectors in the truncated basis will be defined, leading to a solution with a higher order than the one obtained by the EBO approach, for the same performance level In the EBO method, both the vectors` choice in the truncated basis and their respective coefficient adjustment are performed simultaneously. The Youla`s parameter is approximated by the class of real, rational, proper and stable transfer function and the project variables are the coefficients of the numerator and denominator polynomials. Although this problem is a non- convex one, its main advantage lies in the possibility of finding controllers of relatively lower orders than ones by EBPE at the same level of performance. In addition, some theoretical results are discussed, where the existence and uniqueness of Mixid H2/Hinf problem solution are proved. It is also shown that the sequence of controllers computed by the proposed methods, as order increase, converges to the solution of the original problem.
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27

Mwawasi, Grace Makanda. "Approximations and asymptotic expansions for the distribution of quadratic and bilinear forms." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56952.

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In this thesis, approximations and asymptotic expansions to the distribution of quadratic and bilinear forms in normal random variables are discussed.
Chi-square type approximations, normal approximations, the mixture approximation and the laplacian approximation to the exact distribution of positive definite and indefinite quadratic forms and bilinear forms are discussed. Several asymptotic results are also discussed.
Some numerical computations giving probabilities and percentage points and also some simulation for the distribution function of quadratic and bilinear forms are given to give more insight into the approximations.
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28

Iafrati, Alessandro. "Floating body impact : asymptotic and numerical solutions." Thesis, University of East Anglia, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501123.

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This thesis is concerned with the estimate of hydrodynamic loads generated during the water entry of bodies, originally floating on a still liquid surface. The analysis assumes the fluid to be ideal and the flow potential. The liquid is treated as incompressible, but the effects of weak compressibility are carefully estimated. A theoretical estimate of the loads in the early stage after the sudden start of the vertical downward motion of the body is derived. The solution is achieved through the method of matched asymptotic expansions, by using the non-dimensional body displacement as a small parameter. A uniformly valid solution is obtained by formulating an inner problem under suitable set of stretched variables and by matching its asymptotic behaviour with the inner limit of the outer solution. The boundary value problem governing the inner solution is strongly nonlinear, with nonlinear boundary conditions imposed on unknown free surface position. The solution is obtained through suitably developed numerical iterative procedures.
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29

Scheidt, Jrgen vom, Hans-Jrg Starkloff, and Ralf Wunderlich. "Asymptotic Expansions for Second-Order Moments of Integral Functionals of Weakly Correlated Random Functions." Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199801269.

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In the paper asymptotic expansions for second-order moments of integral functionals of a class of random functions are considered. The random functions are assumed to be $\epsilon$-correlated, i.e. the values are not correlated excluding a $\epsilon$-neighbourhood of each point. The asymptotic expansions are derived for $\epsilon \to 0$. With the help of a special weak assumption there are found easier expansions as in the case of general weakly correlated functions.
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30

EGAMI, SHIGEKI, and KOHJI MATSUMOTO. "ASYMPTOTIC EXPANSIONS OF MULTIPLE ZETA FUNCTIONS AND POWER MEAN VALUES OF HURWITZ ZETA FUNCTIONS." Cambridge University Press, 2002. http://hdl.handle.net/2237/10284.

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31

MATSUMOTO, KOHJI, and MASANORI KATSURADA. "Explicit Formulas and Asymptotic Expansions for Certain Mean Square of Hurwitz Zeta-Functions: III." Cambridge University Press, 2002. http://hdl.handle.net/2237/10253.

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32

Hasnain, Shahid. "Steady Periodic Water Waves Solutions Using Asymptotic Approach." Thesis, Linköpings universitet, Tillämpad matematik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69421.

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The aim of this work is to study the relation between two invariants of water flow in a channel of finite depth. The first invariant is the height of the water wave and the second one is the flow force. We restrict ourselves to water waves of small amplitude. Using asymptotic technique together with the method of separation of variables, we construct all water waves of small amplitude which are parameterized by a small parameter. Then we demonstrate numerically that the flow force depends monotonically on the height.
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33

Arsentieva, Kseniya. "Asymptotic solutions of porous medium and inviscid flow." Thesis, University of Oxford, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711763.

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34

Moriarty, Julie Ann. "A nonlinear theory for thin aerofoils with non-thin trailing edges /." Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09SM/09smm854.pdf.

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35

Kidane, Addis Asmelash. "An experimental and analytical study of graded materials under thermo-mechanical dynamic loading /." View online ; access limited to URI, 2009. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3380532.

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36

Blyth, Mark Gregory. "Steady flow in dividing and merging pipes." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7633.

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37

Chen, Cuixian. "Asymptotic properties of the Buckley-James estimator for a bivariate interval censorship regression model." Diss., Online access via UMI:, 2007.

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38

Pillay, Samara. "The narrow escape problem : a matched asymptotic expansion approach." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1428.

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We consider the motion of a Brownian particle trapped in an arbitrary bounded two or three-dimensional domain, whose boundary is reflecting except for a small absorbing window through which the particle can escape. We use the method of matched asymptotic expansions to calculate the mean first passage time, defined as the time taken for the Brownian particle to escape from the domain through the absorbing window. This is known as the narrow escape problem. Since the mean escape time diverges as the window shrinks, the calculation is a singular perturbation problem. We extend our results to include N absorbing windows of varying length in two dimensions and varying radius in three dimensions. We present findings in two dimensions for the unit disk, unit square and ellipse and in three dimensions for the unit sphere. The narrow escape problem has various applications in many fields including finance, biology, and statistical mechanics.
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39

Ludewig, Matthias [Verfasser], and Christian [Akademischer Betreuer] Bär. "Path integrals on manifolds with boundary and their asymptotic expansions / Matthias Ludewig ; Betreuer: Christian Bär." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1219149195/34.

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40

Yu, Dong-Sheng 1963. "Asymptotic solutions of dendritic crystal growth in external flow." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36740.

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The present thesis is concerned with the effect of external fluid flow on steady axisymmetric dendrtic growth from a undercooled pure melt with zero surface tension. We consider two limiting cases: (1) the weak flow case, where the velocity of the forced external floe is much less than dendrite tip growth velocity; (2) the strong flow case, where the velocity of the forced external flow is much larger than dendrite tip growth velocity, and obtain uniformly valid asymptotic expansion solutions in terms of the generalized Laguerre series representation. For the case of weak external flow, we have a regular perturbation problem. The solution is obtained by using the regular perturbation expansion method. For the case of strong external flow, we have a singular boundary problem. The solution is found by using matched asymptotic expansion technique.
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41

Xue, Fei. "Asymptotic solutions of almost diagonal differential and difference systems." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4556.

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42

Yu, Dong-Sheng. "Asymptotic solutions of dendritic crystal growth in external flow." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ64702.pdf.

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43

Rand, Peter. "Asymptotic analysis of solutions to elliptic and parabolic problems." Doctoral thesis, Linköping : Matematiska institutionen, Linköpings universitet, 2006. http://www.bibl.liu.se/liupubl/disp/disp2006/tek1044s.pdf.

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44

Searcy, Chad Randall. "A multiscale model for predicting damage evolution in heterogeneous viscoelastic media." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1251.

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A multiple scale theory is developed for the prediction of damage evolution in heterogeneous viscoelastic media. Asymptotic expansions of the field variables are used to derive a global scale viscoelastic constitutive equation that includes the effects of local scale damage. Damage, in the form discrete cracks, is allowed to grow according to a micromechanically-based viscoelastic traction-displacement law. Finite element formulations have been developed for both the global and local scale problems. These formulations have been implemented into a two-scale computational model Numerical results are given for several example problems in order to demonstrate the effectiveness of the technique.
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45

Malevich, Nadja [Verfasser], and Gerd [Akademischer Betreuer] Christoph. "Approximations and asymptotic expansions for sums of heavy-tailed random variables / Nadja Malevich. Betreuer: Gerd Christoph." Magdeburg : Universitätsbibliothek, 2015. http://d-nb.info/1077557531/34.

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46

Bencheikh, L. "Scattering of elastic waves by cylindrical cavities : Integral-equation methods and low-frequency matched asymptotic expansions." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376270.

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47

Issaka, Aziz. "Analysis of Variance Based Financial Instruments and Transition Probability Densities Swaps, Price Indices, and Asymptotic Expansions." Diss., North Dakota State University, 2018. https://hdl.handle.net/10365/31742.

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This dissertation studies a couple of variance-dependent instruments in the financial market. Firstly, a number of aspects of the variance swap in connection to the Barndorff-Nielsen and Shephard model are studied. A partial integro-differential equation that describes the dynamics of the arbitrage-free price of the variance swap is formulated. Under appropriate assumptions for the first four cumulants of the driving subordinator, a Ve\v{c}e\v{r}-type theorem is proved. The bounds of the arbitrage-free variance swap price are also found. Finally, a price-weighted index modulated by market variance is introduced. The large-basket limit dynamics of the price index and the ``error term" are derived. Empirical data driven numerical examples are provided in support of the proposed price index. We implemented Feynman path integral method for the analysis of option pricing for certain L\'evy process-driven financial markets. For such markets, we find closed form solutions of transition probability density functions of option pricing in terms of various special functions. Asymptotic analysis of transition probability density functions is provided. We also find expressions for transition probability density functions in terms of various special functions for certain L\'evy process-driven markets where the interest rate is stochastic.
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48

AMAR-SERVAT, Emmanuelle. "Asymptotic solutions and resonances for Klein-Gordon and Schrödinger operators." Phd thesis, Université Paris-Nord - Paris XIII, 2002. http://tel.archives-ouvertes.fr/tel-00002342.

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Mon travail de thèse se situe dans le cadre de l'analyse semi-classique. Il se divise en trois parties. Dans la première, j'ai étudié l'opérateur de Klein-Gordon semi-classique en dimension un. Dans la zone où le potentiel reste sous le niveau d'énergie, il existe pour cet opérateur des constructions de solutions WKB, similaires à celles développées pour l'opérateur de Schrödinger. Sous certaines hypothèses, on a prolongé ces solutions hors de cette zone, grâce aux méthodes utilisées près des points tournants pour l'opérateur de Schrödinger. On a ensuite étudié un exemple pour lequel on peut faire des calculs explicites. Enfin, en dimension quelconque, on a obtenu une nouvelle majoration des fonctions propres, lorsque la distance d'Agmon associée à cet opérateur a un gradient lipschitzien. La deuxième partie concerne l'opérateur de Schrödinger et l'étude des résonances en dimension un. Lorsque le potentiel présente deux puits et une mer pour les niveaux d'énergies considérés, on a obtenu des conditions de non croisement des résonances ainsi que leur graphe, grâce à la construction de modes. En présence d'un nombre quelconque de puits, cela permet également de calculer une estimation de la partie imaginaire des résonances dans le cas d'une interaction simple. Enfin, dans la troisième partie, on considère un opérateur de Schrödinger dont le potentiel présente un maximum non dégénéré. On a étudié les résonances générées par une courbe homocline qui passe par ce maximum. En dimension un, on a obtenu une condition de quantification, et par suite les résonances recherchées. En dimension quelconque, on a construit une solution asymptotique sortante le long de cette courbe, en adaptant la méthode de B. Helffer et J. Sjöstrand pour le fond de puits non résonnant. Une transformation FBI permet ensuite de conjecturer un premier niveau de résonances.
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49

Guo, Shiyan. "Asymptotic Analysis of Wave Propagation through Periodic Arrays and Layers." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8886.

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In this thesis, we use asymptotic methods to solve problems of wave propagation through infinite and finite (only consider those that are finite in one direction) arrays of scatterers. Both two- and three-dimensional arrays are considered. We always assume the scatterer size is much smaller than both the wavelength and array periodicity. Therefore a small parameter is involved and then the method of matched asymptotic expansions is applicable. When the array is infinite, the elastic wave scattering in doubly-periodic arrays of cavity cylinders and acoustic wave scattering in triply-periodic arrays of arbitrary shape rigid scatterers are considered. In both cases, eigenvalue problems are obtained to give perturbed dispersion approximations explicitly. With the help of the computer-algebra package Mathematica, examples of explicit approximations to the dispersion relation for perturbed waves are given. In the case of finite arrays, we consider the multiple resonant wave scattering problems for both acoustic and elastic waves. We use the methods of multiple scales and matched asymptotic expansions to obtain envelope equations for infinite arrays and then apply them to a strip of doubly or triply periodic arrays of scatterers. Numerical results are given to compare the transmission wave intensity for different shape scatterers for acoustic case. For elastic case, where the strip is an elastic medium with arrays of cavity cylinders bounded by acoustic media on both sides, we first give numerical results when there is one dilatational and one shear wave in the array and then compare the transmission coefficients when one dilatational wave is resonated in the array for normal incidence. Key words: matched asymptotic expansions, multiple scales, acoustic scattering, elastic scattering, periodic structures, dispersion relation.
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50

Stewart, Michael. "Asymptotic methods for tests of homogeneity for finite mixture models." Connect to full text, 2002. http://hdl.handle.net/2123/855.

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Thesis (Ph. D.)--University of Sydney, 2002.
Title from title screen (viewed Apr. 28, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Mathematics and Statistics, Faculty of Science. Includes bibliography. Also available in print form.
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