Optical properties of free electrons in the conduction band of metal are considered. It is shown that the conventional Drude theory does not take shielding of the external electrical field by mobile electrons into account. This shielding is conditioned by the polarization of these electrons. Offered is the way of taking this polarization into consideration when calculating the reflectivity of metal. It is shown that the account of polarization results in agreement between the theoretical results and experimental data.

The influence of polarization of conduction electrons in semiconductor on their light absorption is examined. The Drude model is used for the description of an electron motion inside conduction band. Account of electron screening the external electric field essentially modifies the expression for the light absorption coefficient in comparison with that in the traditional theory. As a result, the absorption spectrum becomes "resonance" like.

The dielectric permeability of the free-electron system in semiconductor is usually considered using the Drude - Lorentz model without taking into account this system polarization. But it seems reasonable to include polarization phenomena into consideration of the free-electron system behavior. In this paper, the position of minimum in plasma optical reflection by the system of free electrons is analyzed with allowance for this system polarization. This position can substantially differ from that given via calculation of it within the framework of the traditional Drude - Lorentz model. This difference is significant when analyzing the available experimental results.

Considered in this paper are optical spectra of crystal lattice vibrations in semiconductor solid solutions, which have two vibration bands depending on solution composition. It has been shown that this dependence for the vibration spectrum is conditioned by polarization of this lattice, which is not taken into account by the traditional theory for the optical spectrum of lattice vibrations.

This paper proposes models and methods of the parametric synthesis of automatic control systems for a steam generator at a nuclear power plant, based on the modification of unconditional optimization methods. A mathematical model of steam generator control systems designed for the synthesis of model parameters has been considered. Algorithms are given for calculating level objective functions that take into consideration the limitations of variable parameters and quality indicators of problems for identifying and optimizing model parameters. The methods of unconditional optimization have been modified by introducing the operation of comparing the values of the level objective functions. Using the information technology of optimization, computational experiments were carried out to synthesize the parameters of the steam generator control systems by optimizing the level objective functions. The values of 54 parameters for the model of the control system in the PGV-1000 steam generator were identified, the value of standard deviation in the processes of 1 % from the experimental processes was achieved in the model. The result of parametric synthesis of optimal control systems for a steam generator produced a minimum control time of 131 seconds while the time of computational experiments did not exceed 10 minutes. The peculiarity of the proposed approach to the parametric synthesis of control system models is that the level objective function as a single mathematical object includes all the information about the synthesis problem. Therefore, a given approach is promising for simplifying software for solving complex problems of parametric synthesis of control systems. The considered technology of parametric synthesis of control systems could increase the degree of scientific validity of technical projects to improve various applied and promising control systems.