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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of dynamics and differential equations 4 (1992), S. 419-443 
    ISSN: 1572-9222
    Keywords: Mixed type ; nonlinear elliptic-hyperbolic problem ; bounded solutions ; center manifolds ; weak normal hyperbolicity ; 35M05 ; 35L70 ; 35B35 ; 47B25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider the equation a(y)uxx+divy(b(y)▽yu)+c(y)u=g(y, u) in the cylinder (−l,l)×∑, being elliptic where b(y)〉0 and hyperbolic where b(y)〈0. We construct self-adjoint realizations in L2(∑) of the operatorAu= (1/a) divy(b▽yu)+(c/a) in the case ofb changing sign. This leads to the abstract problem uxx+Au=g(u), whereA has a spectrum extending to +∞ as well as to −∞. For l=∞ it is shown that all sufficiently small solutions lie on an infinite-dimensional center manifold and behave like those of a hyperbolic problem. Anx-independent cross-sectional integral E=E(u, ux) is derived showing that all solutions on the center manifold remain bounded forx→ ±∞. For finitel, all small solutionsu are close to a solutionũ on the center manifold such that ‖u(x)-ũ(x)‖ Σ ⩽Ce -α(1-|x|) for allx, whereC andα are independent ofu. Hence, the solutions are dominated by hyperbolic properties, except close to the terminal ends {±1}×∑, where boundary layers of elliptic type appear.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 43 (1992), S. 449-470 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Bifurkation in unbeschränkten Gebieten führt häufig auf spontane Musterbildung. Dabei wird ein periodisches Grundmuster, das aus dem linearen System ableitbar ist, durch nichtlineare Effekte auf großen Raum- und Zeitskalen moduliert. Die Modulation der Amplitude wird meist durch die Ginzburg-Landau-Gleichung beschrieben. Für die Untersuchung solcher System entwickeln wir ein Verallgemeinerung des Lyapunov-Schmidtschen Reduktionsverfahren, das die Behandlung eines kontinuierlichen Spektrums erlaubt. Damit können wir parabolische Systeme in Plattengebieten auf ein niedrigdimensionaleres Problem zurückführen, das im Linearteil eine partielle Differentialgleichung bezüglich der unbeschränkten Variablen ist, das aber im Nichtlinearteil auch nichtlokale Terme enthält. Unter Verwendung des Modulationsansatzes mit großen Zeit- und Raumskalen führt die Entwicklung nach dem Bifurkations-parameter zu lokalen Termen, die Ableitungen der Amplitudenfunktion enthalten. Wir erhalten genau die klassischen Modulationsgleichungen vom Ginzburg-Landau-Typ.
    Notes: Abstract Bifurcation problems in unbounded domains often lead to spontaneous pattern formation. A basic periodic pattern, derivable from the linearized system, is modulated by nonlinear effects on a slow time and space scale. The modulation of the amplitude is usually described by equations of Ginzburg-Landau type. To study such problems we develop a generalized Lyapunov-Schmidt reduction procedure which allows to treat the case of continuous spectra. Thus, we are able to reduce parabolic systems in plate-like domains to a lower dimensional problem, which is, to first order, a partial differential equation in the unbounded variables only, but contains also non-local terms in the nonlinearity. Using a modulation ansatz with slow time and space variables, the expansion in terms of the bifurcation parameter transfers the non-local terms into local ones involving derivatives of the amplitude function. Thus, we recover the classical modulation equations of Ginzburg-Landau type.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 44 (1993), S. 386-388 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 46 (1995), S. 820-822 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 133 (1995), S. 145-198 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The existence and linear stability problem for the Stokes periodic wavetrain on fluids of finite depth is formulated in terms of the spatial and temporal Hamiltonian structure of the water-wave problem. A proof, within the Hamiltonian framework, of instability of the Stokes periodic wavetrain is presented. A Hamiltonian center-manifold analysis reduces the linear stability problem to an ordinary differential eigenvalue problem on ℝ4. A projection of the reduced stability problem onto the tangent space of the 2-manifold of periodic Stokes waves is used to prove the existence of a dispersion relation Λ(λ,σ, I 1, I 2)=0 where λ ε ℂ is the stability exponent for the Stokes wave with amplitude I 1 and mass flux I 2 and σ is the “sideband’ or spatial exponent. A rigorous analysis of the dispersion relation proves the result, first discovered in the 1960's, that the Stokes gravity wavetrain of sufficiently small amplitude is unstable for F ε (0,F0) where F 0 ≈ 0.8 and F is the Froude number.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 101 (1988), S. 319-348 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 110 (1990), S. 351-352 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 110 (1990), S. 353-372 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The concept of normal hyperbolicity of center manifolds is generalized to infinite-dimensional differential equations, in particular, to elliptic problems in cylindrical domains. It is shown that all solutions u staying close to the center manifold for t ∈ (−l,l) satisfy an estimate of the form $$\left\| {u(t) - \tilde u(t)} \right\| \leqslant Ce^{ - \alpha (l - |t|)} $$ where C and α are independent of l, and ũ is a solution on the center manifold. These results are applied to Saint-Venant's principle for the static deformation of nonlinearly elastic prismatic bodies. The use of the center manifold permits the effective treatment of the general case of non-zero resultant forces and moments acting on each cross-section.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 129 (1995), S. 101-127 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The “spatial dynamics” approach is applied to the analysis of bifurcations of the three-dimensional Poiseuille flow between parallel plates. In contrast to the classical studies, we impose time periodicity as well as spatial periodicity with period 2π/α in the streamwise direction. However, we make no assumptions on the behavior in the spanwise direction, except the uniform closeness of the bifurcating solution to the basic flow. In an abstract setting it is shown how the dimension of the critical eigenspace of the spatial dynamics analysis can be uniquely determined from the classical linear stability problem. For the three-dimensional Poiseuille problem we are able to find all relevant coefficients from the analysis of the purely two-dimensional problem. Moreover, we are able to analyze precisely the influence of a spanwise pressure gradient and the associated spanwise mass flux. The study of the reduced problem shows that there are two different kinds of solutions (spirals and ribbons) which are 2αp/β periodic in the spanwise direction, as in the Couette-Taylor problem, and both of them bifurcate in the same direction.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 102 (1988), S. 205-229 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Saint-Venant's problem consists in finding elastic deformations of an infinite prismatic body taking given values for the cross-sectional resultants of force and moment. Using the center manifold approach we show that all deformations having sufficiently small bounded strains lie on a finite-dimensional manifold. In particular, the flow on this manifold is described by a set of equations having exactly the form of the classical rod equations. Moreover, the set of semi-inverse solutions can be analyzed locally.
    Type of Medium: Electronic Resource
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