Vol 68, No 10 (2023)

All currently known methods and methods for the formation of fractal
features of polarimetric radar images. Briefly reviewed new
texture-fractal feature – a directional multifractal signature measured morphologically by the iterative covering method. In relation to the analysis of polarimetric images formed by a synthetic aperture radar, a new concept for their processing is proposed, based on the possibility of taking into account the polarization differences of ground-based spatially distributed objects by identifying the multifractal and anisotropic properties of their texture. A variant of interpretation of the obtained results for automatic optimization of further successful solution of specific segmentation (classification) problems underlying surface, detection and recognition of ground objects.

The possibility of excitation of acoustic vibrations of a spherical thin film by electromagnetic waves is considered. A comparison of the numerical and analytical solutions is given. The concept of spatial resonance is introduced. It has been shown that not only frequency is important, but also wavelength. The results obtained can be used to measure parameters of various environments and for medical purposes.

Hafnium oxide (HfO_2) films were synthesized onto silicon substrates by magnetron sputtering under various technological conditions. Research results presented structural composition of HfO2 films and electrical properties of heterostructures metal-insulator-semiconductor (Ni–HfO_2–Si) based on them.

The results of the experimental determination of the spin Hall angle in a two-layer metal/ferromagnet structure Pt/La_0.7 Sr_0.3 MnO_3, obtained from the angular dependences of the longitudinal and transverse spin magnetoresistance in the planar Hall effect configuration are presented. The spin Hall angle determined from the longitudinal magnetoresistance was θ_Hx ≈ 0.016, and from transverse θ_Hy ≈ 0.018, while for SrIrO_3/La_0.7 Sr_0.3 MnO_3 heterostructures the ratio of the transverse to longitudinal spin Hall angle turned out to be significantly higher, θ_Hy/θ_Hx ≈ 9, which is most likely caused by the formation of a layer with high conductivity at the SrIrO_3 boundary /La_0.7 Sr_0.3 MnO_3. 

The results of the development of a meander-type slow-wave system (SS) with metal supports for a miniature high-power W-band traveling wave lamp (TWT) with two ribbon electron beams are presented. Using a three-dimensional finite element software package, the electrodynamic parameters of the GS were studied. A two-section model of a TWT amplifier with a discontinuity has been developed to prevent self-excitation. Three-dimensional modeling of electron-wave interaction was carried out. It was found that with a total beam current of 200 mA in linear mode, the gain exceeds 30 dB in the frequency band 95.4...97.75 GHz, and the output power in saturation mode reaches 120 W. A technology for manufacturing SS based on laser microprocessing of thin copper plates is proposed. Test samples of the SS were manufactured and verified using optical and scanning microscopy.

Superconducting integrated structures intended for matching generator impedances based on a distributed Josephson junction and detector based on a superconductor–insulator–superconductor tunnel junction in the subterahertz frequency range. The structures were modeled using the transfer matrix method. The designs were calculated in a three-dimensional numerical modeling program. A qualitative agreement was found between the results obtained by the two methods. Three designs have been designed with various topologies covering the frequency range 250...680 GHz at a level of –2 dB

The analysis of the possibility of using a chaotic communication scheme based on
synchronization of the receiver and transmitter, which used hyperbolic chaos generators. It is shown that useful information nonlinearly mixed into the transmitter signal can be detected by the receiver if it is in stable synchronization with the transmitted signal. Research has been conducted to confirm the hypothesis that the roughness, strong chaotic properties and noise-like broadband spectrum of this type of generator provide greater reliability and stability of transmission. The influence of noise and frequency distortions of the signal in the communication channel on the quality of information detection by the receiver is also shown.

The possibility of assessing the influence of external conditions, such as glucose content in solution and external lighting, on life activity has been shown
blue-green algae with control mode real time. Using fabricated fiber sensors, the time dependence, lasting more than 40 hours, and changes in the refractive index of a suspension containing microalgae Chlorella Vulgaris during their life activity were studied.

The influence of the thickness of a tunnel-thin charge carrier-depleted carbon
layer in an enriched non-crystalline carbon matrix for dissipative transport and
field emission of electrons. It has been established that the “geometric” increase in self-energy electrons increases the transparency of potential barriers to dissipative transport in the heterostructure and at the solid-vacuum interface. It has been shown that the introduction of a quantum barrier into the carbon matrix increases the transverse current and rectifying properties of heterostructures, increases the field current density and the steepness of the current-voltage characteristics.

The mechanism of formation of a nutation line in a flowing liquid is considered. New ones have been developed equations of motion of the longitudinal and transverse components of the magnetization vector in the nutation coil, which take into account the inhomogeneity of the magnetic field ΔH_0 in the zone of influence of the radio frequency field H_1 on the flowing liquid. The equations also take into account the nature of the change in the value of the magnetic field inhomogeneity ΔH_0 when the fluid moves along the nutation coil. The results of experimental studies of the shape of the nutation line are presented. Theoretical calculations are compared with experimental data.

A simulation of a TiNi shape memory alloy plate was carried out at various crystallographic orientations using a free package for classical molecular dynamics LAMMPS. It was found that the crystallographic orientation of the plate has a significant effect on the phase transition temperature. The dependence of surface energy on temperature for crystallographic orientations (100), (110), (112), (122) was constructed. The stability of the model used was investigated, as a result of which its applicability in these calculations was confirmed.