Vol 68, No 3 (2023)

The review presents the third part of the experimental study of emission and the optoelectronic effects excited by it. At the beginning of a powerful optical picosecond pumping of the GaAs layer of the AlxGa1 – xAs–GaAs–AlxGa1 – xAs heterostructure, a picosecond emission has occurred in it. It has been
experimentally proved that this is enhanced spontaneous (stimulated) emission with the propagation specifics in the heterostructure. It has been shown that the electron–hole plasma is maintained in a “threshold” state with an inversion of the electron population in a narrow energy range because of high emission intensity. In this regard, the electron temperature and therefore, their distribution between valleys, etc., becomes uniquely related to their density. It has been found that limiting the inversion meant the emission amplification saturation when the amplification is limited by the energy transport of charge carriers to the levels from which they are forced to recombine. It has been determined that the transport being slowed down by the heating of carriers because of their interaction with emission determines the dynamics of the emission as a whole and its spectral components when the temperature of the carriers is related to their density.

A signal processing technique is proposed that allows one to reconstruct two-dimensional radio images of objects with angular super-resolution. The method of double orthogonalization is justified, which allows one to increase the level of the achieved super-resolution. The limiting possibilities of obtaining adequate
solutions to inverse problems in the presence of a priori information about the solution are shown.

The properties of angular noise of radar reflections from the rotor head are considered. On the basis of a multipoint geometric model of the rotor head, analytical expressions are obtained that allow calculating the parameters of the probability distribution density of angular noise for the azimuth planes and the elevation of the rotor head of a single-bladed screw at an undirected angle of the control sleeve. Correlation obtained for one blade rotor head is generalized to thease of a rotor head with an arbitrary number of blades. It is shown that the rotor head angular noise is a random process with periodically changing parameters. The theoreticalresults are confirmed by mathematical modeling.

The principles of analysis and optimization of the parameters and signal processing mode in an information transmission system with a reverse channel operating under the influence of intentional interference, the structure of which can be selected from the position of disruption (deterioration) of the system have been considered. An algorithm for the formation and processing of pseudorandom signals with a randomized base is proposed, which provides an increase in the speed of information transmission by the system in the
class of interference with limited average power while ensuring the initial reliability indicators. The methodology is presented, calculation examples are given, and graphs of the dependences of the guaranteed information
transfer rate in a system with a randomized two-stage switching of the signal base from the average power of the optimized interference are shown.

The transformation of the trajectories of surface magnetostatic waves propagating in a ferrite film magnetized by a linearly nonuniform field caused by a high-power femtosecond laser pulse is considered. A decrease in the magnetization of the film due to an increase in its temperature can be used to account for the effect of light on wave propagation. The stepwise transformation of the trajectories of propagating waves that is synchronous with the time parameters of the femtosecond pulse is revealed. The transformation of trajectories is interpreted using the method of isofrequency curves and the Hamilton–Auld method.

Acoustic signals coming from the human head during mental activity are experimentally studied. Acoustic signals that differ from the signals during relaxation are revealed. Calculation of the multiplication table in the mind is used as mental activity. It is shown that the differences are due to a variation in the breathing pattern. It is also shown that the most informative signals related to respiration are observed from the crown region (at a point close to Cz used in encephalography) and the signals related to pulse activity are observed from the temple region (at point T3).

A transition is made from piecewise continuous functions of the memristor model with threshold type switching to differentiable functions described by a single formula. Systems of equations are obtained and numerically solved for circuit sections in which the memristive device is connected in series with other discrete elements, a conventional resistor, diode, inductor, and capacitor. For the case of a serial connection of a memristor and a resistor, the calculated data are compared with the experiment. The case of series connection of a memristor and a semiconductor diode has been studied in detail. The assumptions concerning the mathematical description and physical interpretation of the influence of the molding process on the memristive system are presented.

The results of the analysis of the features of the charge pumping process in devices with switched capacitors, as well as the features of switching processes in transient operating modes, are presented. The methods by which a high efficiency of charge pumping is achieved are considered. Circuit modeling made it possible to refine the characteristics of processes, minimize conversion losses, formulate recommendations for choosing the parameters of converter elements, and generating control signals.