Vol 24, No 1 (2021)

In this work, the authors investigated the dynamics of entanglement of two identical two-level atoms (qubits) in the framework of the two-photon double Jaynes–Cummings model, taking into account the detuning between atoms and the double frequency of the field modes of the resonators, as well as the Kerr medium in both resonators. The authors derived the time dependence of the negativity parameter for the Bell initial states of the atoms and the vacuum states of the resonator fields. The results showed that detuning and Kerr nonlinearity leads to stabilization of the entanglement for all initial Bell-type atomic states. For some initial atomic entanglement states, the detuning and Kerr environment in the resonators can prevent the effect of sudden death of the atom-atom entanglement.

Exact mathematic models were developed for traveling wave antennas with a constant slot width based on the dyadic Green function, taking into account both the main and cross-polarization components of the field in the far radiation zone. The possibility of using these models as basic models for studying the electrodynamic properties of traveling wave antennas with a different slot configuration (linearly, exponentially tapering, etc.) is justified. The influence of the geometric parameters of the investigated traveling wave antennas on their characteristics was studied by means of using the established mathematic models. It has been found that in the electrodynamic E plane, with an increase of the length and width of the slot, the main beam of the radiation pattern narrows, which leads to an increase the directed properties of the antennas. In the electrodynamic H plane, the width of the main beam of radiation pattern decreases only as the length of the slot of traveling wave antennas increases and does not depend on its width in practice. It was shown that the established theory results of the study are well consistent with the results of experiments, which also revealed the limitations of the applicability of the developed models. Analysis of traveling wave antennas characteristics was carried out at central frequency of 10 GHz in the frequency range of 8-12 GHz.

The article discusses the methodology for developing a predictive model (forecasting operator) of the quality of onboard equipment using the extrapolation method. It is shown that the most efficient information about the quality and reliability of the equipment can be obtained from the results of autonomous tests. The choice of the test object was made. A microprocessor temperature controller was chosen as the object of autonomous tests. The transition resistance between the electrical circuits of the microprocessor temperature controller was chosen as a predicted parameter. The results of the training experiment are presented. To construct the forecasting operator, quasi-deterministic models of linear, logarithmic, exponential, and parabolic forms are used. When developing the models, the normalization of predicted parameter by mathematical expectation was used. The choice of predictive models was based on the criteria of minimum average variance, calculated at the test time points, and the minimum values of the probability of erroneous decisions and consumer risk. The research of the developed operator was carried out, probabilistic characteristics of its efficiency are obtained.

The algorithm of homography superposition of the television signals was shown in this article. The algorithm allows improving noise immunity for homography parameters of television signal with textural fragments. The core of the estimation procedure of homography parameters for image superposition is the matching of the feature points. The feature points are local extremes of the pixel brightness of the image. The matching is defined by the maximum correlation coefficient between a region of the image of a neighbor area of the feature point. The log-polar system of the images provides an invariant correlation of scale and rotate are proportional offsets along the axis in this coordinate system. The noise immunity is provided due to the developing procedure of removing feature points in the textural region. This procedure leads to decreasing probability of error matching of the feature points. The numerical modeling shows high noise immunity of the developed procedure in comparing the current researches.

The fundamental difference of the voltage converter of the secondary power supply source for the transmitter-receiver modules of active electronically scanned arrays with impulse load and variable duty cycle from traditional voltage converters that constantly consume power from the primary network is shown. Methods for improving the quality of transient processes in voltage converter with constant power consumption during start-up by soft start are not applicable to improve the quality of transients in periodic current pulses caused by a pulsed load. Since any ripples, noises, instabilities in the power supply of the transmitter-receiver modules of active electronically scanned arrays operating in a linear mode lead to parasitic amplitude modulation of the emitted signal and to a deterioration in the quality of selection and target tracking, very strict requirements are imposed on the quality of the transmitter-receiver modules supply voltage (voltage ripple k_п ≤ 0,5 %, the amount of overshoot of the output voltage s_U ≤ 2 %, etc.). The article shows that such a quality of the output voltage with a pulsed load of the transmitter-receiver modules of active electronically scanned arrays can be obtained using a lower-type voltage converter, with a double-circuit negative feedback for the output voltage and current of the inductor, with a storage capacitor and with a power smoothing filter with the characteristics of Chebyshev and Butterworth. The work investigated the influence of the negative feedback depth on the output voltage and current of the smoothing filter choke, the value of the storage capacitor capacity, the type and parameters of the smoothing filter, and recommendations were given to select their optimal values, at which the required quality of the supply voltage for the transmitter-receiver modules of active electronically scanned arrays was ensured, taking into account the minimization of their dimensions.

The use of standard instruments (colorimeters) when measuring the color coordinates and chromaticity of multicolored objects and having relatively large dimensions is practically impossible. This is due to the fact that ordinary colorimeters, no matter what method is implemented in them, are designed to determine the color of a specific point of the measured object. This article discusses a method for determining the color of a multicolored and relatively large object, for example, a car, color photography, art painting, etc. Let us call this method computer colorimetry. A practical solution to this method can be used in such areas of the national economy, as, for example, repainting a car after damage to certain parts of the body with damage to the paintwork, automatic control and video surveillance of forest and peatland areas to detect fires, in the examination of the authenticity of documents and works of art, and other areas of the national economy.