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The academic journal «Doklady BGUIR» has been published since 2003 by the Belarusian State University of Informatics and Radioelectronics. Original articles in Russian and English are accepted for publication in the journal. Articles are subject to mandatory review.

Current issue

Vol 22, No 6 (2024)
View or download the full issue PDF (Russian)
5-13 123
Abstract

Al/g-C3N4/Si/Al, Al/g-C3N4/SiO2/Si/Al, Al/g-C3N4/Al and Al/g-C3N4/Al2O3/Al structures were fabricated by rapid chemical vapor deposition of graphitic carbon nitride (g-C3N4) from melamine onto silicon (Si) and aluminum (Al) substrates partially coated with appropriate oxide – SiO2 or Al2O3 – and Al contacts deposited on the surface. Their capacitance-voltage characteristics and frequency dependence of the capacitance were measured at room temperature. It was found that the permittivity of g-C3N4 is 14 in structures on silicon and 9–10 in structures on aluminum. The decrease in permittivity is explained by the formation of Al2O3 at the g-C3N4/Al boundary during the deposition of g-C3N4, as indicated by the results of the X-ray diffraction analysis of the formed samples.

14-20 126
Abstract

The Fabry – Perot oscillations in specular reflection spectra in the visible wavelength range depending on the anodic alumina thickness have been investigated. The anodic alumina was formed in 1.0 M H2SO4 aqueous solution with the 1:1 water to ethylene glycol solution additive. The oxides fabrication conditions have been established whose reflection spectra were characterized by high intensity of oscillations to be used in sensor structures. Using these optical oscillations data, the anodic alumina effective refractive indices have been calculated; the increase by 0.04 has been revealed in the isopropyl alcohol solution compared to the air medium for the 2 to 5 micrometer thick samples. The ability to determine the anodic alumina porosity using the Fabry – Perot oscillation shift in the different refractive indices media has been shown. A good agreement between the porosity values obtained from the reflection spectra calculations and the electron microscopic images has been established.

21-28 111
Abstract

Monodisperse silica globules of about 250–300 nm in size have been synthesized by the sol-gel method. These globules form the basis for the synthesis of artificial opals – three-dimensional photonic crystals and disordered opal matrices. Matte coatings on quartz glass consisting of monodisperse silica globules and barium titanate xerogel doped with erbium and ytterbium, demonstrating up-conversion luminescence of erbium, have been synthesized. A change in the photonic band gap caused by heat treatment in the reflectance spectra of synthetic opals containing barium titanate xerogel and residues of ethylene glycol not removed by heat treatment has been shown.

29-37 122
Abstract

The issues of realization of ultra-high-frequency measuring mixers on harmonics with a built-in frequency diplexer and the relevance of their application are considered. A mathematical model of a measuring harmonic mixer of the millimeter-wave range as a linear device is described. A functional diagram and technical characteristics of a measuring harmonic mixer with a built-in frequency diplexer are given. The results of computer modeling of the module of the diplexer transmission coefficient by the high-frequency input and low-frequency output, as well as the standing wave ratio by the voltage of the measuring channel of the harmonic mixer in the frequency range from 78.33 to 118.10 GHz are shown. The implementation of the developed mixer in this frequency range is presented.

38-44 100
Abstract

One of the promising technological directions for the implementation of multi-crystal modules is the assembly of 3D modules. The peculiarity of this technology is the arrangement of the assembly components not only in the horizontal plane, but also vertically. The formation of contact connections between the components of the 3D module can be carried out using wire mounting, as well as using surface mounting technology. To implement the latter, it is necessary to form vias in the silicon wafer. When creating vias between the layers of the multi-crystal module, the focused energy of the laser beam is used. Since the diameter of the holes can be larger than the diameter of the laser beam, it is necessary to move the beam along a given trajectory. To select the trajectory of the focused laser beam, a simulation of the visualization of the laser movement during the formation of a hole for the speeds of 0.5 mm/s and 5 mm/s was carried out. Modeling was performed in COMSOL Multiphysics 5.6, which made it possible to obtain the distribution of thermal fields during laser flashing of holes in the silicon substrate.

45-51 102
Abstract

The possibility of using telecommunication optical fiber as a basis for creating a light sensor is shown. The light sensor is a section of optical fiber wound on a cylindrical base turn to turn. A photodetector is connected to the output end of this fiber section. When comparing the possibility of using single-mode and multimode telecommunication optical fiber in the sensor, it is noted that multimode optical fiber is most suitable for creating such a sensor. It is established that the sensitivity of the sensor to the luminous flux increases with a decrease in the bending radius of the optical fiber and with an increase in the number of turns of the sensor. Dependences of the sensitivity of the sensor to the luminous flux on the number of turns and their diameter are obtained, which allow developing specific design solutions for such sensors.

52-61 121
Abstract

To analyze the electromagnetic compatibility of low-orbit satellite constellations оf communication (LOSCC) with ground-based radio systems, the power flux density of radio-frequency electromagnetic radiation generated by LOSCC near the Earth’s surface was estimated. The estimate is based on the analysis of LOSCC system characteristics, spacecraft and ground segment (subscriber terminals, gateway stations) parameters. The conditions under which spacecraft radiation can cause interference with the functioning of terrestrial fixed communication services, including radio relay communication lines, using the same frequencies on a secondary basis were analyzed. It was found that with an increase in the number of spacecraft and gateway stations in the LOSCC, the probability of interference with the functioning of the radio relay line from this LOSCC decreases due to an inc rease in the minimum elevation angle of subscriber terminals. However, an increase in the number of deployed LOSCCs requires stricter requirements for the functioning of each of them to prevent interference.

62-69 94
Abstract

The article deals with heuristic neural network-based solver for NP-hard problems (determining the (in)consistency of a system of logical equations). This problem is relevant and important, for example, when performing express analysis of the consistency of the knowledge base of an expert system, decision-ma king based on fuzzy logic models, recognition of multidimensional objects, etc. The trained neural network plays the role of a highly efficient heuristic solver, and the number of equations and variables used in the logical model has little effect on the speed of decision-making by the neural network, while the probability of an exact solution for a parametrically defined class of problems is close to one. A parametrically defined class of problems is understood as a set of problems described by multidimensional vectors of parameters that satisfy some general law of probability distribution. One such family of parameters, proposed and used for training a neural network, is given in the article. It is shown how to generate inconsistent and consistent instances of individual systems of logical equations. A series of more than 200 experiments to test the model was carried out, the limits of the confidence interval of the probability of a correct decision were obtained, which allows us to evaluate the effectiveness of the model. It is shown how to implement a neural network to check the (in)consistency of a logical knowledge model. The constructed model can be effectively supplemented with new parameter vectors and applied in various fields of applied research.

70-80 109
Abstract

The paper presents a mathematical description of pulse systems and phase synchronization devices using the state variable method. The generalized structural diagram of a pulse system with phase control is analyzed. A mathematical description of the processes occurring in the system in the following operating modes – the number of pulses from the feedback circuit and the number of pulses from the device input are equal, the output signal frequency is less than the specified one is proposed, as well as the frequency detection mode with a significant excess of the feedback circuit signal frequency. The considered mathematical models of the studied class of devices take into account the nonlinear nature of systems operating in the frequency phase detection mode, and significantly reduce the calculation time when modeling processes on a computer.

81-89 110
Abstract

This work presents the results of computer simulations of the operational characteristics of vertical channel Insulated Gate Bipolar Transistor (IGBT) device structures designed according to the following technologies: Trench-IGBT, Superjunction Trench-IGBT (SJ-IGBT), Deep Trench SJ-IGBT (DT-SJ-IGBT), Floating p-region SJ-IGBT (FP-SJ-IGBT), and Step-Doped Collector Trench-IGBT. The operating principles of these insulated gate bipolar transistor design solutions are discussed. A particular focus is placed on the Step-Doped Collector Trench-IGBT structure, which demonstrates reduced switching losses.

90-96 103
Abstract

Modern requirements for clinical testing of medical devices include biophysical modeling of therapy methodology on human phantoms with known bioelectric properties of all tissues. The article presents modeling on a platform with tools recommended by the FDA for clinical trials and implemented in Sim4Life V8.0. Simulations of the effect of infrasound at frequencies of 18 and 32 Hz on infiltrated tissues of the phantom foot were conducted.

97-102 98
Abstract

Surface electromyography of spontaneous muscle activity is the most common method for assessing the functional state of the muscle complex. The surface electromyogram signal has a noise-like appearance with a signal amplitude changing over time. The change in background activity and the probability of high-amplitude amplitude spikes, a short-term significant increase in the electromyogram amplitude, were studied. A change in background activity can be associated with both technical factors, such as changes in the resistance of the skin-electrode contact, and directly with the state of the muscle complex and the inability of the muscles to relax instantly. High-amplitude spikes can also appear due to many factors – electrode displacement, recording of extraneous muscle contractions, muscle spasms, etc. Synchronous electromyograms of the temporal and masseter muscles were analyzed. The study of background activity and the presence of high-amplitude spikes showed a difference in the rate of muscle relaxation before and after the functional load test, as well as a difference in the rate of relaxation between the temporal and masseter muscles.

103-111 115
Abstract

The paper discusses methods and algorithms of artificial intelligence aimed at automating and optimizing business processes in e-commerce. The possibilities of using artificial intelligence to personalize customer offers, predict consumer behavior and segment customers using machine learning methods are presented. The features of the application of artificial intelligence in such large companies as Amazon, Walmart, OZON and Netflix are analyzed, where it allows improving the accuracy of forecasts and automating decision-making processes. It is proposed to use natural language processing methods and neural networks to automatically generate advertising descriptions of goods, which helps to increase the effectiveness of marketing strategies and reduce costs.

Announcements

2024-08-09

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