103 research outputs found

### Scattering below critical energy for the radial 4D Yang-Mills equation and for the 2D corotational wave map system

We describe the asymptotic behavior as time goes to infinity of solutions of
the 2 dimensional corotational wave map system and of solutions to the 4
dimensional, radially symmetric Yang-Mills equation, in the critical energy
space, with data of energy smaller than or equal to a harmonic map of minimal
energy. An alternative holds: either the data is the harmonic map and the
soltuion is constant in time, or the solution scatters in infinite time

### Global well-posedness of the KP-I initial-value problem in the energy space

We prove that the KP-I initial value problem is globally well-posed in the
natural energy space of the equation

### Local well-posedness and blow up in the energy space for a class of L2 critical dispersion generalized Benjamin-Ono equations

We consider a family of dispersion generalized Benjamin-Ono equations (dgBO)
which are critical with respect to the L2 norm and interpolate between the
critical modified (BO) equation and the critical generalized Korteweg-de Vries
equation (gKdV). First, we prove local well-posedness in the energy space for
these equations, extending results by Kenig, Ponce and Vega concerning the
(gKdV) equations. Second, we address the blow up problem in the spirit of works
of Martel and Merle on the critical (gKdV) equation, by studying rigidity
properties of the (dgBO) flow in a neighborhood of solitons. We prove that when
the model is close to critical (gKdV), solutions of negative energy close to
solitons blow up in finite or infinite time in the energy space. The blow up
proof requires in particular extensions to (dgBO) of monotonicity results for
localized versions of L2 norms by pseudo-differential operator tools.Comment: Submitte

### On the supercritical KDV equation with time-oscillating nonlinearity

For the initial value problem (IVP) associated to the generalized
Korteweg-de Vries (gKdV) equation with supercritical nonlinearity,
\begin{equation*}
u_{t}+\partial_x^3u+\partial_x(u^{k+1}) =0,\qquad k\geq 5,
\end{equation*}
numerical evidence [Bona J.L., Dougalis V.A., Karakashian O.A., McKinney W.R.: Conservative, high-order numerical schemes for the generalized Korteweg–de Vries equation. Philos. Trans. Roy. Soc. London Ser. A 351, 107–164 (1995) ] shows that, there are initial data $\phi\in
H^1(\mathbb{R})$ such that the corresponding solution may blow-up in finite time.
Also, with the evidence from numerical simulation [Abdullaev F.K., Caputo J.G., Kraenkel R.A., Malomed B.A.: Controlling collapse in Bose–Einstein condensates by temporal modulation of the scattering length. Phys. Rev. A 67, 012605 (2003) and Konotop V.V., Pacciani P.: Collapse of solutions of the nonlinear Schrödinger equation with a time dependent nonlinearity: application to the Bose–Einstein condensates. Phys. Rev. Lett. 94, 240405 (2005) ], it has been
claimed that a periodic time dependent coefficient in the nonlinearity would disturb the
blow-up solution, either accelerating or delaying it.
In this work, we investigate the IVP associated to the gKdV equation
\begin{equation*}
u_{t}+\partial_x^3u+g(\omega t)\partial_x(u^{k+1}) =0,
\end{equation*}
where $g$ is a periodic function and $k\geq 5$ is an integer. We prove that, for given
initial data $\phi \in H^1(\mathbb{R})$, as $|\omega|\to \infty$, the solution $u_{\omega}$
converges to the solution $U$ of the initial value problem associated to
\begin{equation*}
U_{t}+\partial_x^3U+m(g)\partial_x(U^{k+1}) =0,
\end{equation*}
with the same initial data, where $m(g)$ is the average of the periodic function $g$.
Moreover, if the solution $U$ is global and satisfies $\|U\|_{L_x^5L_t^{10}}<\infty$, then
we prove that the solution $u_{\omega}$ is also global provided $|\omega|$ is
sufficiently large.M. P. was partially supported by the Research Center of Mathematics of the University of Minho, Portugal through the FCT Pluriannual Funding Program, and through the project PTDC/MAT/109844/2009, and M. S. was partially supported by FAPESP Brazil

### On the regularity of solutions to the k-generalized korteweg-de vries equation

This work is concerned with special regularity properties of solutions to the k-generalized Korteweg-de Vries equation. In [Comm. Partial Differential Equations 40 (2015), 1336–1364] it was established that if the initial datum is u0 ∈ Hl ((b, ∞)) for some l ∈ Z+ and b ∈ ℝ, then the corresponding solution u(·, t) belongs to Hl ((β, ∞)) for any β ∈ ℝ and any t ∈ (0, T). Our goal here is to extend this result to the case where l > 3/4

### Hardy uncertainty principle, convexity and parabolic evolutions

We give a new proof of the $L^2$ version of Hardy’s uncertainty principle based on calculus and on its dynamical version for the heat equation. The reasonings rely on new log-convexity properties and the derivation of optimal Gaussian decay bounds for solutions to the heat equation with Gaussian decay at a future time.We extend the result to heat equations with lower order variable coefficient.IT641-13 (GIC12/96), DMS-0968472, DMS-126524

### The mixed problem in L^p for some two-dimensional Lipschitz domains

We consider the mixed problem for the Laplace operator in a class of
Lipschitz graph domains in two dimensions with Lipschitz constant at most 1.
The boundary of the domain is decomposed into two disjoint sets D and N. We
suppose the Dirichlet data, f_D has one derivative in L^p(D) of the boundary
and the Neumann data is in L^p(N). We find conditions on the domain and the
sets D and N so that there is a p_0>1 so that for p in the interval (1,p_0), we
may find a unique solution to the mixed problem and the gradient of the
solution lies in L^p

### Global well-posedness for the KP-I equation on the background of a non localized solution

We prove that the Cauchy problem for the KP-I equation is globally well-posed
for initial data which are localized perturbations (of arbitrary size) of a
non-localized (i.e. not decaying in all directions) traveling wave solution
(e.g. the KdV line solitary wave or the Zaitsev solitary waves which are
localized in $x$ and $y$ periodic or conversely)

### Blow-up of critical Besov norms at a potential Navier-Stokes singularity

We show that the spatial norm of any strong Navier-Stokes solution in the space X must become unbounded near a singularity, where X may be any critical homogeneous Besov space in which local existence of strong solutions to the 3-d Navier-Stokes system is known. In particular, the regularity of these spaces can be arbitrarily close to -1, which is the lowest regularity of any Navier-Stokes critical space. This extends a well-known result of Escauriaza-Seregin-Sverak (2003) concerning the Lebesgue space $L^3$, a critical space with regularity 0 which is continuously embedded into the spaces we consider. We follow the "critical element" reductio ad absurdum method of Kenig-Merle based on profile decompositions, but due to the low regularity of the spaces considered we rely on an iterative algorithm to improve low-regularity bounds on solutions to bounds on a part of the solution in spaces with positive regularity

### Global well-posedness for a coupled modified kdv system

We prove the sharp global well-posedness result for the initial value problem
(IVP) associated to the system of the modi ed Korteweg-de Vries (mKdV) equation. For
the single mKdV equation such result has been obtained by using Mirura's Transform that
takes the KdV equation to the mKdV equation [8]. We do not know the existence of Miura's
Transform that takes a KdV system to the system we are considering. To overcome this
di culty we developed a new proof of the sharp global well-posedness result for the single
mKdV equation without using Miura's Transform. We could successfully apply this technique
in the case of the mKdV system to obtain the desired result.Fundação para a Ciência e a Tecnologia (FCT

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