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Quasilinear hyperbolic equations with hysteresis

Augusto Visintin (2004)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Hysteresis operators are illustrated, and a weak formulation is studied for an initial- and boundary-value problem associated to the equation 2 / t 2 u + F u + A u = f ; here F is a (possibly discontinuous) hysteresis operator, A is a second order elliptic operator, f is a known function. Problems of this sort arise in plasticity, ferromagnetism, ferroelectricity, and so on. In particular an existence result is outlined.

Quasilinear waves and trapping: Kerr-de Sitter space

Peter Hintz, András Vasy (2014)

Journées Équations aux dérivées partielles

In these notes, we will describe recent work on globally solving quasilinear wave equations in the presence of trapped rays, on Kerr-de Sitter space, and obtaining the asymptotic behavior of solutions. For the associated linear problem without trapping, one would consider a global, non-elliptic, Fredholm framework; in the presence of trapping the same framework is available for spaces of growing functions only. In order to solve the quasilinear problem we thus combine these frameworks with the normally...

Quasi-periodic oscillations for wave equations under periodic forcing

Massimiliano Berti, Michela Procesi (2005)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Existence of quasi-periodic solutions with two frequencies of completely resonant, periodically forced, nonlinear wave equations with periodic spatial boundary conditions is established. We consider both the cases the forcing frequency is (Case A) a rational number and (Case B) an irrational number.

Quasi-symmetrization of hyperbolic systems and propagation of the analytic regularity

Piero D'Ancona, Sergio Spagnolo (1998)

Bollettino dell'Unione Matematica Italiana

Dopo aver introdotto la nozione di quasi-simmetrizzatore per sistemi del prim'ordine debolmente iperbolici, si dimostra che ad ogni sistema di tipo Sylvester, cioè proveniente da un'equazione scalare di ordine superiore, si può associare in modo regolare un quasi-simmetrizzatore. Come applicazione di questo risultato si prova che, per qualunque sistema semi-lineare N × N debolmente iperbolico, le soluzioni Gevrey in x di ordine s < N / N - 1 restano analitiche non appena lo siano all'istante iniziale.

Quenching time of some nonlinear wave equations

Firmin K. N’gohisse, Théodore K. Boni (2009)

Archivum Mathematicum

In this paper, we consider the following initial-boundary value problem u t t ( x , t ) = ε L u ( x , t ) + f ( u ( x , t ) ) in Ω × ( 0 , T ) , u ( x , t ) = 0 on Ω × ( 0 , T ) , u ( x , 0 ) = 0 in Ω , u t ( x , 0 ) = 0 in Ω , where Ω is a bounded domain in N with smooth boundary Ω , L is an elliptic operator, ε is a positive parameter, f ( s ) is a positive, increasing, convex function for s ( - , b ) , lim s b f ( s ) = and 0 b d s f ( s ) < with b = const > 0 . Under some assumptions, we show that the solution of the above problem quenches in a finite time and its quenching time goes to that of the solution of the following differential equation α ' ' ( t ) = f ( α ( t ) ) , t > 0 , α ( 0 ) = 0 , α ' ( 0 ) = 0 , as ε goes to zero. We also show that the above result remains...

Radiation fields

Piotr T. Chruściel, Olivier Lengard (2005)

Bulletin de la Société Mathématique de France

We study the “hyperboloidal Cauchy problem” for linear and semi-linear wave equations on Minkowski space-time, with initial data in weighted Sobolev spaces allowing singular behavior at the boundary, or with polyhomogeneous initial data. Specifically, we consider nonlinear symmetric hyperbolic systems of a form which includes scalar fields with a λ φ p nonlinearity, as well as wave maps, with initial data given on a hyperboloid; several of the results proved apply to general space-times admitting conformal...

Reachability of nonnegative equilibrium states for the semilinear vibrating string by varying its axial load and the gain of damping

Alexander Y. Khapalov (2006)

ESAIM: Control, Optimisation and Calculus of Variations

We show that the set of nonnegative equilibrium-like states, namely, like ( y d , 0 ) of the semilinear vibrating string that can be reached from any non-zero initial state ( y 0 , y 1 ) H 0 1 ( 0 , 1 ) × L 2 ( 0 , 1 ) , by varying its axial load and the gain of damping, is dense in the “nonnegative” part of the subspace L 2 ( 0 , 1 ) × { 0 } of L 2 ( 0 , 1 ) × H - 1 ( 0 , 1 ) . Our main results deal with nonlinear terms which admit at most the linear growth at infinity in y and satisfy certain restriction on their total impact on (0,∞) with respect to the time-variable.

Recent progress in attractors for quintic wave equations

Anton Savostianov, Sergey Zelik (2014)

Mathematica Bohemica

We report on new results concerning the global well-posedness, dissipativity and attractors for the quintic wave equations in bounded domains of 3 with damping terms of the form ( - Δ x ) θ t u , where θ = 0 or θ = 1 / 2 . The main ingredient of the work is the hidden extra regularity of solutions that does not follow from energy estimates. Due to the extra regularity of solutions existence of a smooth attractor then follows from the smoothing property when θ = 1 / 2 . For θ = 0 existence of smooth attractors is more complicated and follows...

Recent progress in the regularity theory of Fourier integrals with real and complex phases and solutions to partial differential equations

Michael Ruzhansky (2003)

Banach Center Publications

In this paper we will give a brief survey of recent regularity results for Fourier integral operators with complex phases. This will include the case of real phase functions. Applications include hyperbolic partial differential equations as well as non-hyperbolic classes of equations. An application to an oblique derivative problem is also given.

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