Consider an operator equation F(u)=0 in a Hilbert space H and assume that this equation is solvable. Let us call the problem of solving this equation ill-posed if the operator F ′(u) is not boundedly invertible, and well-posed otherwise. A general method, Dynamical Systems Method (DSM), for solving linear and nonlinear illposed problems in H is presented. This method consists of the constructio...

In the present article an energy distribution function of heterogeneous solid was estimated. Energy distribution function is an important characterization for heterogeneous adsorbent. An overall adsorption quantity for a heterogeneous solid is usually expressed by a first kind of Fredholm equation, which contains unknown distribution function and local adsorption isotherm as a kernel. The calcu...

The main goal of our paper is to study the regularization problems which occur in predictive control of systems with severely ill-posed inverse model. We propose a new formulation of predictive control where the future controls are obtained as a solution of certain ill-posed inverse problem. This formulation leads to a possibility of closed loop on-line control of complex systems with ill-posed...

Under certain scaling the nonlinear Schrödinger equation with random dispersion converges to the nonlinear Schrödinger equation with white noise dispersion. The aim of this work is to prove that this latter equation is globally well posed in L or H. The main ingredient is the generalization of the classical Strichartz estimates. Additionally, we justify rigorously the formal limit described abo...

Considering the Cauchy problem for the Korteweg-de Vries-Burgers equation ut + uxxx + ǫ|∂x| u+ (u)x = 0, u(0) = φ, where 0 < ǫ, α ≤ 1 and u is a real-valued function, we show that it is globally well-posed in Hs (s > sα), and uniformly globally well-posed in H s (s > −3/4) for all ǫ ∈ (0, 1). Moreover, we prove that for any T > 0, its solution converges in C([0, T ]; Hs) to that of the KdV equa...

In this paper we investigate the solvability of an ill-posed two-dimensional Fred-holm integral equation of the rst kind which allows the solutions of distribution type. The problem is rst transformed into a well-posed diierential-integral equation using output least-squares approach with a regularization of bounded variations. A globally convergent iterative method is proposed and some numeric...

The concern of this paper is the Cauchy problem for the Prandtl equation. This problem is known to be well-posed for analytic data [13, 10], or for data with monotonicity properties [11, 15]. We prove here that it is linearly ill-posed in Sobolev type spaces. The key of the analysis is the construction, at high tangential frequencies, of unstable quasimodes for the linearization around solution...

We consider parabolic stochastic partial differential equations driven by multiplicative Lévy noise of an affine type. For the second moment of the mild solution, we derive a well-posed deterministic space-time variational problem posed on tensor product spaces, which subsequently leads to a deterministic equation for the covariance function.

A nonlinear operator equation F (x) = 0, F : H → H, in a Hilbert space is considered. Continuous Newton’s-type procedures based on a construction of a dynamical system with the trajectory starting at some initial point x0 and becoming asymptotically close to a solution of F (x) = 0 as t → +∞ are discussed. Well-posed and ill-posed problems are investigated.

Motivated by the paraxial narrow–angle approximation of the Helmholtz equation in domains of variable topography that appears as an important application in Underwater Acoustics, we analyze a general Schrödinger-type equation posed on two-dimensional variable domains with mixed boundary conditions. The resulting initialand boundary-value problem is transformed into an equivalent one posed on a ...