DCDS

We study an optimal boundary control
problem (OCP) associated to a linear elliptic equation $-\mathrm{div}\,\left(\nabla y+A(x)\nabla y\right)=f$. The characteristic feature of this equation is the fact that the matrix $A(x)=[a_{ij}(x)]_{i,j=1,\dots,N}$ is skew-symmetric, $a_{ij}(x)=-a_{ji}(x)$, measurable, and belongs to $L^2$-space (rather than $L^\infty$). In spite of the fact that the equations of this type can exhibit non-uniqueness of weak solutions--- namely, they have approximable solutions as well as another type of weak solutions that can not be obtained through an approximation of matrix $A$, the corresponding OCP is well-possed and admits a unique solution. At the same time, an optimal solution to such problem can inherit a singular character of the original matrix $A$. We indicate two types of optimal solutions to the above problem: the so-called variational and non-variational solutions, and show that each of that optimal solutions can be attainable by solutions of special optimal boundary control problems.

MCRF

In this paper we study an optimal control
problem (OCP) associated to a linear elliptic equation on a bounded domain $\Omega$. The
matrix-valued coefficients $A$ of such systems is our control in $\Omega$ and will be taken in
$L^2(\Omega;\mathbb{R}^{N\times N})$ which in particular may comprises the case of unboundedness. Concerning the boundary value problems associated to the equations of this
type, one may exhibit non-uniqueness of
weak solutions--- namely, approximable solutions as well as another type of weak solutions that can not be obtained through the $L^\infty$-approximation of matrix $A$.
Following the direct method in the calculus of variations, we
show that the given OCP is well-possed and admits at least one solution.
At the same time, optimal solutions to such problem may have a singular character in the above sense.
In view of this we indicate two types of optimal solutions to the above problem: the so-called variational and non-variational solutions, and show that some of that optimal solutions can not be attainable through the $L^\infty$-approximation of the original problem.

DCDS-B

We study an optimal control problem for one class of non-linear elliptic equations with $p$-Laplace operator and $L^1$-nonlinearity. We deal with such case of nonlinearity when we cannot expect to have a solution of the state equation for any given control. After defining a suitable functional class in which we look for solutions, we reformulate the original problem and prove the existence of optimal pairs. In order to ensure the validity of such reformulation, we provide its substantiation using a special family of fictitious optimal control problems. The idea to involve the fictitious optimization problems was mainly inspired by the brilliant book of V.S. Mel'nik and V.I. Ivanenko "Variational Methods in Control Problems for the Systems with Distributed Parameters", Kyiv, 1998.

MCRF

In this paper we study we study a Dirichlet optimal control problem
associated with a linear elliptic equation the coefficients of which
we take as controls in the class of integrable functions. The characteristic feature of this control object is the fact that the skew-symmetric part of matrix-valued control $A(x)$ belongs to $L^2$-space (rather than $L^\infty)$. In spite of the fact that the equations of this type can exhibit non-uniqueness of weak solutions, the corresponding OCP, under rather general assumptions on the class of admissible controls, is well-posed and admits a nonempty set of solutions [9]. However, the optimal solutions to such problem may have a singular character.
We show that some of optimal solutions can be attainable by solutions of special optimal control problems in perforated domains with fictitious boundary controls on the holes.

DCDS-B

In this paper we study an optimal boundary control problem for the
3D steady-state Navier-Stokes equation in a cylindrically perforated
domain $\Omega_{\epsilon}$. The control is the boundary velocity field
supported on the 'vertical' sides of thin cylinders. We minimize the
vorticity of viscous flow through thick perforated domain. We show
that an optimal solution to some limit problem in a non-perforated
domain can be used as basis for the construction of suboptimal
controls for the original control problem. It is worth noticing that
the limit problem may take the form of either a variational
calculation problem or an optimal control problem for Brinkman's law
with another cost functional, depending on the cross-size of thin
cylinders.

NHM

We discuss the optimal control
problem (OCP) stated as the minimization of the queues and the
difference between the effective outflow and a desired one for the
continuous model of supply chains, consisting of a PDE for the
density of processed parts and
an ODE for the queue buffer occupancy. The main goal is to consider this problem with pointwise
control and state constraints. Using the so-called Henig delation, we propose the relaxation approach to characterize the solvability and regularity of the original problem by analyzing the corresponding relaxed OCP.

NHM

We discuss the optimal control
problem stated as the minimization in the $L^2$-sense of the mismatch between the actual out-flux and a demand forecast for a hyperbolic conservation law that models a highly re-entrant production system. The output of the factory is described as a function of the work in progress and the position of the switch dispatch point (SDP) where we separate the beginning of the factory employing a push policy from the end of the factory, which uses a quasi-pull policy. The main question we discuss in this paper is about the optimal choice of the input in-flux, push and quasi-pull constituents, and the position of SDP.