Introduction. The creation of a modern electronic component base with improved characteristics is possible with the use of new materials and technologies for their manufacture. Therefore, it is important to analyze the electrical parameters of electronic components when using materials in their design that expand their functionality. Stabilization of the electrical properties of capacitors with variable capacitance when the control voltage changes due to temperature influences is an urgent task. Its solution can be performed using a set of nonlinear dielectrics, the properties of which mutually compensate for the instability of the capacitance over a wide temperature range.

Aim. Creation of computational models of planar slit structures containing multilayer films with thickness-variable stoichiometric compositions of ferroelectric materials. Based on such structures, it becomes possible to design capacitors whose capacitance varies from the control voltage and which can be used as concentrated circuit elements operating in the low–frequency - microwave wavelength ranges and having high temperature stability.

Materials and methods. Computational mathematical models for the analysis of layered structures are performed using the method of conformal maps and the use of boundary conditions for tangential and normal components of the electric field.

Results. The capacitance of slit and plane-parallel capacitors on multilayer structures is analyzed. The results of calculating the capacitance of capacitors from the number of ferroelectric layers and their thicknesses with various stoichiometric compositions providing the required stability in a given temperature range are obtained. Increasing the number of layers in the structure from three to five expands the temperature range of stabilization of the effective dielectric constant of the tank from ~50 °C to ~120…160 °C.

Conclusion. The created mathematical models made it possible to numerically evaluate the temperature and field stability of multilayer film structures based on barium strontium compositions for their use as a basis for constructing a component base with electrical capacity adjustment.

Introduction. Stable operation of multi-element antenna systems, in particular waveguide-slotted phased antenna arrays (WSPAA), ensures the required noise immunity and electromagnetic compatibility of radio-electronic equipment for various purposes. However, such performance indicators are subject to deterioration due to the random nature of changes in the phases of antenna elements (AE) under the action of malfunction of phase shifters (PS). Therefore, operation evaluation of WSPAAs in the event of PS failure with any outcome is an urgent research task. The paper reviews algorithms for modeling the impact of PS failures on WSPAAs and evaluates the operation of such antenna systems under these impacts.

Aim. Development of an algorithm for assessing the impact of a complete PS shutdown on WSPAA characteristics, as well as operation evaluation of WSPAAs in the event of PS malfunction with different outcomes.

Materials and methods. Statistical modeling methods were used to study the impact of PS failures on WSPAA characteristics. Calculations were carried out using in the Mathcad 15 software environment.

Results. The conducted simulation revealed three types of faults, for which the following PS parameters were set: the phase took a value equal to 0, instead of the required one; the phase took a random value with a discrete value of 22.5°, instead of the required one; complete switching off of the PS. When studying up to 35 faulty PS of an AE from 50 elements, the following characteristics were changed: standard deviation – from 0.056 to 0.18; relative values: radiation pattern width – from 8 to 32 %; level of side lobes – from 13 to 78 %; radiation power – from 0.9 to 0.31. A range of WSPAA states was formed upon the occurrence of PS failures: "Normal operation" – up to 7 faulty PS; "Deterioration of parameters" – from 7 to 12 faulty PS; "Failure" – more than 12 faulty PS.

Conclusion. The results obtained can be used when designing radio-electronic systems with antenna arrays. Future research should be aimed at developing a methodology for operational monitoring of the state of antenna systems, as well as studying the compensation of characteristic distortions in case of various malfunctions.

Introduction. Increased attention is currently paid to the issues of stealth operation of various radar systems. The article considers the possibility of increasing the energy stealth of a radar system with a complex quasi-continuous signal due to additional spatial modulation of the probing signal in the radiation mode and the use of MIMO technology when receiving and processing reflected signals.

Aim. Research and comparative analysis of the energy stealth of a radar system with a space–time modulated probing signal with ternary amplitude–phase modulation based on a pseudo-random sequence of maximum length.

Materials and methods. The analysis of energy stealth is based on the theory of signals concerning the issues of formation and processing of complex modulated phase–code signals with a large base. A quasi-continuous ternary signal based on a pseudo-random sequence of maximum length and a regular pulse sequence providing decoupling of reception and transmission when using a single transceiver phased array was selected as a research object. A similar radar system with the same probing signal and identical N-element phased array without additional spatial modulation was used as a reference. In order to eliminate energy losses during reception and processing of reflected signals in the radar system with additional spatial modulation, MIMO technology was used.

Results. Quantitative estimates of the gain in the signal level accumulated in the integrating filters of the power receiver for different accumulation time durations commensurate with the period or time of coherent processing of the radar probing signal were obtained. The cases of known and unknown carrier frequencies of the radar signal on the side of the power receiver were analyzed. In addition, the effect of the deviation of the phased array pattern from the direction to the carrier of the power receiver was analyzed. The advantage of the proposed method of spatial modulation of a signal based on a pseudo-random sequence with the property of an additive cyclic shift consists in the absence of transformation of the uncertainty function, which ensures the preservation of its correlation properties.

Conclusion. The obtained theoretical and simulation results indicate an improved stealth of radar operation due to additional spatial modulation of the probing signal. The use of MIMO technology allowed energy losses during the reception and processing of reflected signals in the radar receiver to be eliminated.

Introduction. Research into the potential use of new telecommunication signals for illumination in passive radar systems is an important task. The development of communication technologies, particularly the emergence of 5G, offers opportunities for the advancement of passive radar systems that utilize 5G transmitters as illuminators. A theoretical analysis of the 5G signal characteristics in the context of its use for illumination in passive radar systems reveals the potential for high resolution in terms of range and velocity. This article presents the results of simulations of the signal processing process in passive radar systems using a 5G signal for two scenarios: with the presence of a single object and two objects in the observation field. The limited availability of 5G networks in Russia impedes experimental studies. Therefore, simulation of the signal processing process in passive radar systems using 5G signals for object illumination is a relevant task.

Aim. Analysis of 5G downlink signal and simulation of signal processing in passive radar with 5G illumination source in different scenarios.

Materials and methods. The theory of signal processing in semi-active radar, 5G standard and structure, a model of the 5G signal propagation channel, and comparative analysis were used. The calculation of the cross-ambiguity function of the passive radar using the 5G signal was carried out by computer simulation.

Results. The conducted simulation of the signal processing process in different scenarios found that passive radar using a 5G signal is capable of detecting targets with good resolution in terms of both range and velocity.

Conclusion. The simulation results further support the potential for effective use of the 5G illumination signal in passive radar for monitoring purposes in relatively small areas.

Introduction. Porous metal oxide nanoparticles are of great scientific and technological importance due to their wide range of applications. Such materials are obtained by co-deposition, sol-gel, microemulsion, hydrothermal, vapor-phase, etc., methods. Currently, porous metal oxide nanoparticles can be obtained by green synthesis from plant extracts.

Aim. Development of a scalable technique for obtaining porous nickel oxide nanoparticles with a high specific surface area. Investigation of the process of forming hierarchical porous nickel oxide nanoparticles by green synthesis.

Materials and methods. Nickel oxide nanoparticles were obtained by green synthesis using an extract of Fumaria officinalis, a medicinal plant. The chemical composition and surface microstructure were studied by X-ray phase analysis, scanning and transmission electron microscopy. The parameters of the resulting porous structure, such as specific surface area, volume, and pore size, were investigated by the methods of thermal desorption and BET.

Results. Large porous agglomerates ranging in size from several to tens of micrometers were obtained. It was shown that centrifugation rate can be used to vary the specific surface area of structures (up to values of Ssa = 130 m² /g). Annealing temperature can also be used to manage the specific surface area of particles. When an optimal temperature is selected, an almost complete removal of organic ligands that stabilize nanoparticles can be achieved. A model for obtaining a developed porous structure by green synthesis is proposed.

Conclusion. Hierarchical porous nickel oxide nanoparticles were obtained by the method of green synthesis using a Fumaria officinalis extract. A technique for obtaining porous nickel oxide nanoparticles with a high specific surface area was developed. It is shown that technological parameters, such as centrifugation rate and annealing temperature, affect significantly the structure and specific surface area of porous nickel oxide nanoparticles. Systems made of porous nanoparticles are promising for use as catalysts, adsorbents, and electrodes, as well as magnetic and photovoltaic materials. Such aggregated nanoparticles are also promising for use in incorporated and encapsulated nanocomposites, and for creating specialized growth platforms.

Introduction. Composite materials based on electrically conductive polymers find application in various fields. However, the rather low mechanical strength of electrically conductive polymers require addition of other components to enhance their, e.g., mechanical properties. Another direction consists in the development of textile-based composite materials for shielding electromagnetic waves. Due to the low specific density and, respectively, low weight, as well as high absorption efficiency, such materials find application in the fields of human protection from electromagnetic radiation.

Aim. Quantitative assessment and analysis of the radio-absorbing properties of two- and three-component textile composites, which emerge due to their electrically conductive and magnetic characteristics.

Materials and methods. S parameters were measured using a Keysight N5232A vector circuit analyzer. Measurements carried out separately in two frequency ranges: 3.9…5.65 GHz and 5.65…8 GHz. Waveguides of a given cross section were used for the selected frequency ranges (3.9…5.65 GHz – 48 × 24 mm; 5.65…8 GHz – 35 × 15 mm). The experimental samples were composite materials based on non-woven textiles consisting of viscose and polyester fiber in a ratio of 60 and 40 wt %, respectively.

Results. The S11 parameters characterizing wave reflection from the sample surface (S_r) (reflection) and the S12 parameters characterizing the sample permeability (S_t ) (transmittance) were determined. Data for single- and multilayered samples was obtained. The dielectric and magnetic permeability of the obtained materials was calculated.

Conclusion. The studied materials showed a high degree of both shielding and absorption of electromagnetic radiation. Magnetite-based samples demonstrated largely shielding properties against electromagnetic radiation; polypyrrole-based samples were characterized by absorbing properties. The total absorption level of 6-mm thick polypyrrole-based samples was 90 %. The obtained electrophysical parameters can be used when designing and modeling of radio-absorbing products based on the studied materials.

Introduction. In this study, we develop a system for assessing the environmental impact of road transport on air quality in cities. The research relevance is determined by the need to create improved approaches to assessing air pollution in cities associated with the load of automobile transport. In this respect, a generalized geoinformation model for identifying the urban areas most exposed to pollution is required. This model can be used when developing measures aimed at improving the environmental situation in St Petersburg.

Aim. Development of theoretical foundations, as well as software and algorithmic support, with the purpose of creation of a geographic information system for modeling urban air pollution.

Materials and methods. The methods of measurement theory mathematics, systems theory mathematics, mathematical modeling, geoinformation data processing, and object-oriented programming were applied.

Results. Following the development of theoretical foundations, a software and algorithmic support complex for a system for assessing the level of air pollution in urban environments under the impact of road transport was created. This system includes the modules of initial data preparation, road network spatial modeling, calculation of pollutant emissions by vehicle flows, and modeling of the distribution of pollutant concentrations for each pollutant. A digital model of road transport pollution in the residential areas of St Petersburg was developed.

Conclusion. The developed software and algorithmic support can serve as the basis for development of a digital air pollution map. This map can be used when managing problems of urban planning and improving urban environment comfort as part of St Petersburg’s strategic development program. The implementation of the developed digital model in the geographic information system of the city provides opportunities for assessing the impact of road pollution on residential infrastructure. Depending on the source data, including various weather and traffic conditions, the model can be used to identify the most dangerous combinations of pollution factors.

Introduction. Currently, work is underway to create specialized software systems designed for metrological synthesis and analysis. Such systems include a set of functional blocks for solving typical metrological tasks. One of these tasks is to determine the characteristics of the measured sample by means of a set of standards. For example, it is required to determine the thickness of a sample using X-ray spectral analysis based on knowledge about the characteristics of a set of standards and taking into account instrumental and methodological errors.

Aim. Development of software and algorithmic support for standard functional blocks of a software system designed for metrological analysis, in terms of performing calculations of X-ray spectral analysis.

Materials and methods. The functional block being developed in the G language and in the GNU Octave software system takes as input the type and characteristics of the distribution law of the instrumental error of the instrument, the values of the exposure dose of radiation for a set of standards and a sample, as well as the thickness of the standards. At the output, this unit outputs the result of measuring the thickness of the sample and its distribution law. Thus, the measurement result includes the instrumental error, the error of the approximation method, as well as the errors of the transformations.

Results. The software and algorithmic support of typical functional blocks of a software system designed to perform calculations of X-ray spectral analysis has been developed. This software allows you to speed up metrological analysis for the task of determining the thickness of a sample based on a number of measurements of a set of standards. The correctness of the software and algorithmic support for typical functional blocks of the software system is confirmed by the examples given, which were implemented by the calculation method, as well as by testing the created software in the graphical programming environment in the G language, and in the GNU Octave software system.

Conclusion. The developed software and algorithmic software will be used in software systems for metrological synthesis and analysis.

Introduction. Liver cancer is a leading cause of death in oncology. The final diagnosis is determined by a pathomorphological analysis of tissue specimens obtained during percutaneous puncture biopsy. Despite its obvious advantages, this method is associated with the possibility of obtaining nondiagnostic specimens and the need for long wait times. Therefore, additional diagnostic methods should be developed to improve the quality of surgical care for oncology patients. Optical methods are a sensitive tool for determining the metabolic characteristics of biotissues. Such methods may improve the efficacy of conventional puncture procedures by developing approaches for rapid diagnosis of liver neoplasm types.

Aim. Development of intraoperative diagnostic methods for in vivo minimally invasive liver cancer surgery that allow differentiation between liver parenchyma and tumors, as well as classification of neoplasm types (primary malignant, metastatic, and benign) based on optical spectroscopy and machine learning.

Materials and methods. The methods of clinical research, descriptive mathematical statistics, and machine learning were used.

Results. Spectroscopic methods of intraoperative diagnostics, tested in clinic settings, are proposed. These methods demonstrated high diagnostic accuracy during percutaneous puncture biopsy of liver neoplasms. Application of the developed classifiers enables detection of pathological changes with a sensitivity and specificity of 0.90 and 0.95, respectively. When a tumor tissue is detected, differentiation of neoplasm type is possible with a sensitivity and specificity reaching 0.80 and 0.95, respectively.

Conclusion. Recent advances in optics have enabled the implementation of optical technologies in minimally invasive surgery, particularly the integration of fiber optic probes into standard puncture needles. The methods described in this paper facilitate preliminary conclusion about the tumor type with automated processing of optical spectroscopy data during puncture interventions. The application of these methods in clinical practice will increase the accuracy and reliability of puncture biopsy, which is essential in determining a personalized treatment strategy.