American Institute of Mathematical Sciences

This work is a natural continuation of an earlier one [1] in which a mathematical model has been studied. This model is based on maturation-velocity structured bacterial population. The bacterial mitosis is mathematically described by a non-compact boundary condition. We investigate the spectral properties of the generated semigroup and we give an explicit estimation of the bound of its infinitesimal generator.

In this article, we implement the algorithm based on the convex integration result proved in [13] and obtain visualizations of the first iterations of the Nash-Kuiper scheme, approximating the anomalous solutions to the Monge-Ampère equation in two dimensions.

We consider the linear thermoelastic plate equations with free boundary conditions in uniform \begin{document}$ C^4 $\end{document}-domains, which includes the half-space, bounded and exterior domains. We show that the corresponding operator generates an analytic semigroup in \begin{document}$ L^p $\end{document}-spaces for all \begin{document}$ p\in(1, \infty) $\end{document} and has maximal \begin{document}$ L^q $\end{document}-\begin{document}$ L^p $\end{document}-regularity on finite time intervals. On bounded \begin{document}$ C^4 $\end{document}-domains, we obtain exponential stability.

For initial value problems associated with operator-valued Riccati differential equations posed in the space of Hilbert–Schmidt operators existence of solutions is studied. An existence result known for algebraic Riccati equations is generalized and used to obtain the existence of a solution to the approximation of the problem via a backward Euler scheme. Weak and strong convergence of the sequence of approximate solutions is established permitting a large class of right-hand sides and initial data.

The dynamic Maxwell equations with a conductivity term are considered. Conditions for the exponential and strong stability of an initial-boundary value problem are given. The permeability and the permittivity are assumed to be \begin{document}$ 3\times 3 $\end{document} symmetric, positive definite tensors. A result concerning solutions of higher regularity is obtained along the way.

In this paper we consider a porous-elastic system consisting of nonlinear boundary/interior damping and nonlinear boundary/interior sources. Our interest lies in the theoretical understanding of the existence, finite time blow-up of solutions and their exponential decay using non-trivial adaptations of well-known techniques. First, we apply the conventional Faedo-Galerkin method with standard arguments of density on the regularity of initial conditions to establish two local existence theorems of weak solutions. Moreover, we detail the uniqueness result in some specific cases. In the second theme, we prove that any weak solution possessing negative initial energy has the latent blow-up in finite time. Finally, we obtain the so-called exponential decay estimates for the global solution under the construction of a suitable Lyapunov functional. In order to corroborate our theoretical decay, a numerical example is provided.

The goal of this paper is to analyze the cost of boundary null controllability for the \begin{document}$ 1-D $\end{document} linear heat equation with the so-called inverse square potential:

\begin{document}$ u_t -u_{xx} - \frac{\mu}{x^2} u = 0, \qquad x\in (0,1), \ t \in (0,T), $\end{document}

where \begin{document}$ \mu $\end{document} is a real parameter such that \begin{document}$ \mu \leq 1/4 $\end{document}. Since the works by Baras and Goldstein [4,5], it is known that such problems are well-posed for any \begin{document}$ \mu \leq 1/4 $\end{document} (the constant appearing in the Hardy inequality) whereas instantaneous blow-up may occur when \begin{document}$ \mu>1/4 $\end{document}. For any \begin{document}$ \mu \leq 1/4 $\end{document}, it has been proved in [52] (via Carleman estimates) that the equation can be controlled (in any time \begin{document}$ T>0 $\end{document}) by a locally distributed control. Obviously, the same result holds true when one considers the case of a boundary control acting at \begin{document}$ x = 1 $\end{document}. The goal of the present paper is to provide sharp estimates of the cost of the control in that case, analyzing its dependence with respect to the two paramaters \begin{document}$ T>0 $\end{document} and \begin{document}$ \mu \in (-\infty, 1/4] $\end{document}. Our proofs are based on the moment method and very recent results on biorthogonal sequences.

In this paper, we study the indirect boundary stabilization of the Timoshenko system with only one dissipation law. This system, which models the dynamics of a beam, is a hyperbolic system with two wave speeds. Assuming that the wave speeds are equal, we prove exponential stability. Otherwise, we show that the decay rate is of exponential or polynomial type. Note that the results hold without the technical assumptions on the coefficients coming from the multiplier method: a sharp analysis of the behaviour of the resolvent operator along the imaginary axis is performed to avoid those artificial restrictions.

We solve the scattering problems for nonlinear Schrödinger equations with an inverse-square potential by applying the energy methods. The methods are optimized to the abstract semilinear Schrödinger evolution equations with nonautonomous terms.