Tomsk State University of Control Systems and Radio-Electronics

Redundancy is widely used to enhance the reliability of various systems. When there is also a need to improve electromagnetic immunity, the technique of modal redundancy (MR) can be applied. This paper presents the findings of a comprehensive study of a microstrip PCB structure with double MR in both its initial state and after failures. The structure is implemented on a double-sided FR-4 printed circuit board, with a total dimension of 130×75×1.5 (mm). The finite element method was employed to conduct electrodynamic simulations of the structure characteristics across a frequency range of 0 to 18 GHz. To validate the simulation outcomes and assess the reproducibility of characteristics, six prototypes were fabricated and their attributes were subsequently evaluated using a vector circuit analyzer. The measurement results demonstrated that the double-MR structure featured low losses at low frequencies and behaved similarly to a reflectionless low-pass filter. The cutoff frequencies were 95, 60, and 105 MHz for the cases before failure when the power was excited to conductors 1, 2, and 3, respectively. The efficiency of suppressing the ultra-wideband and narrowband electromagnetic interference (EMI) was evaluated using <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-norms. The results demonstrated that the investigated structure can attenuate EMI by all five <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>-norms, both before and after failures. The signal integrity analysis indicated that the structure with double MR can be utilized in low-frequency circuits with data rates up to 200 Mbps. A comparative study was conducted with structures with single and triple MR and demonstrated that the structure with double MR produced the best results for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub>, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> norms.

This study investigates the influence of microgravity on the fundamental frequency (F0) of astronauts’ speech. A speech corpus was compiled, including recordings in microgravity and on Earth, matched by speaker and content. The signal processing methodology included filtering with consideration of human auditory perception, segmentation of speech fragments, F0 estimation using digital signal processing techniques, and visualization through fundamental frequency dynamics plots. Results revealed a consistent increase in F0 for most astronauts under microgravity, with maximum values of 450 Hz for female speakers and 245 Hz for male speakers. Elevated F0 levels were observed for approximately 86% of the total duration of speech fragments recorded in microgravity, compared with 14% on Earth. These findings confirm that microgravity affects the speech apparatus and acoustic characteristics of voice. Practical implications include adapting voice-controlled systems and automatic speech recognition for space environments, monitoring crew condition, and studying speech physiology under extreme conditions.

Continuous authentication is a promising method for protecting computer systems in the event of compromise of primary authentication factors, such as passwords or tokens. Systems employing continuous authentication that rely on biometrics may not be restricted to a single biometric characteristic; rather, they can simultaneously utilize multiple characteristics and subsequently arrive at a conclusive decision based on their collective analysis outcomes. One of the significant challenges researchers encounter when investigating effective fusion in decision-making is the lack of data. At present, data generation primarily involves the creation of feature vectors or attack simulation. This paper introduces a method for directly generating distances derived from a Siamese neural network, utilizing the probability density function of an existing distribution. Through statistical analysis, we successfully generated 5000 samples that correspond to the initial distribution, which were then employed to discover the threshold values at which FAR and FRR were less than 1%. The methods developed can be further applied to identify the most efficient strategies for integrating the results of continuous authentication in systems that incorporate multiple biometric characteristics.

With the development of digital interaction, there is a need to control the information distributed by users so that it complies with legal requirements. The study proposes a technique for classifying Russian-language texts by considering both the biological sex of the authors (male and female) and gender-related distinctions, including heterosexual and homosexual groups as well as specific LGBT categories such as gay men, lesbian women, bisexual, and transgender authors. The article proposes a technique for identifying the sex and gender of authors of Russian-language texts by utilizing an ensemble of methods, including Support Vector Machines (SVM), Convolutional Neural Networks (CNN), and the Russian Bidirectional Encoder Representations from Transformers (RuBERT). This research is introducing a technique for gender identification in Russian texts, as prior studies have only addressed the automatic determination of an author’s sex. To conduct the study, custom datasets of user comments from social networks were created and annotated with both sex and gender labels. In tasks related to identifying the author’s sex, the proposed technique achieved an accuracy exceeding 90 %. This includes the classification of heterosexual men and women as well as a mixed dataset comprising both heterosexual and homosexual individuals. When distinguishing individuals of the same sex based on sexual orientation, the results showed that homosexual and heterosexual women display uncommon writing styles in contrast to men of different orientations, with accuracy rates of 93 % for women and 85 % for men. Additionally, an experiment focused on identifying LGBT individuals and their gender identities based on writing style achieved an accuracy of 93 %. The key takeaway from this study is that combining CNN, RuBERT, and SVM leads to a more robust model for gender classification. The method has been tested on varying numbers of samples. In the basic experiments for determining sex, the method achieves an accuracy of 92 %. When addressing the task of detecting the author’s LGBT affiliation, the method achieves 93 % accuracy. The proposed technique can be applied for automated monitoring of social networks to detect and analyze the gender identity of text authors. It is also promising for use in content moderation systems as well as in sociological and linguistic research.

The objective of this study was to determine the impact of general characteristics of a risk-based approach on the certainty of tax participants' behavior. This study utilized systematic review methods, economic and mathematical modeling, and game theory. The PRISMA methodology was used to conduct systematic reviews. This methodology involves searching databases for articles of interest using keywords. Of the 4,585 articles identified for the period 2013–2025, 38 studies were included in the qualitative synthesis after completing the identification, selection, and eligibility screening stages. The search for sources was conducted on ResearchGate and Scopus platforms. Based on the results of the systematic review, the risk-based approach mechanism is presented as a system of three interrelated elements: the organization of tax risk assessment, the prevention mechanism, and the tax risk avoidance mechanism. The selected scientific papers include studies of risk-based approaches in tax control systems in 15 countries. In analyzing the qualitative data obtained, we formulated characteristics common to all the countries studied for each element of the risk-based approach to tax control. To study taxpayer behavior under various risk-based tax control systems, we applied game theory, specifically the zero-sum antagonist game model, as the most appropriate way to characterize tax relations between the state and taxpayers. It should be noted that the zero-sum antagonist game model includes different behavioral strategies depending on certain conditions. This condition is represented by the parameter of uncertainty in the participants' behavior. Using the Fechner coefficient, we established the relationship between these parameters and each of the formulated general characteristics of the risk-based approach. The cross-country model, formed in the form of a system of mathematical equations based on the identified relationships, confirms the hypothesis posed in this study.

Background. Intentional electromagnetic excitations in the circuit ground are investigated. A patented modal filter characterized by two signal strongly coupled conductors and two circuit ground conductors is considered. The conductive excitation of an ultra-short pulse (USP) in the circuit ground of this modal filter is modeled. Aim. Assessment of the levels of crosstalk at the near and far ends of the modal filter when it is excited by a USP in the circuit ground. Methods. Quasi-static modeling of the time response in the frequency domain by a modified nodal method using the method of moments to calculate the matrices of per-unit-length parameters of a multi-wire transmission line. Results. The voltage waveforms in the active and passive conductors of the modal filter with different boundary conditions at the ends of the active conductor demonstrate that without taking into account losses the crosstalk level reaches 34 % at the near end of the modal filter and minus 55 % at the far end, relative to half of the amplitude of the electromotive force of the USP excitation with duration of 3 ns. Conclusion. The results indicate that the USP excitation in one circuit ground conductor relative to another, produced by a generator with a low internal resistance, can double the levels of crosstalk in the modal filter signal conductors. These levels can reach quarter of the excitation electromotive force amplitude. Therefore, it is recommended to assess the threat of such interference to similar structures.

The study of speech signals relies on carefully curated audio recordings, which are compiled and stored within specialized speech corpora. This article provides a comprehensive overview of such corpora across multiple languages, with particular focus on Russian, English, and Arabic. It notes that Russian and Arabic are represented by fewer corpora compared to the more extensive resources available for English. The discussion includes an examination of typical speech corpus structures, a description of standard parameters for characterizing corpora, and an outline of common metrics used to describe the speech signal itself.

Some aspects determining the electrical strength of the accelerating gap in a fore-vacuum-pressure plasma-cathode electron beam source utilizing helium and argon as the working gas were explored. Penetration of plasma into the accelerating gap is the cause of breakdown. We find that gap breakdown occurs at larger emission hole diameter and at higher plasma density in helium than in argon. The greater stability of the plasma boundary in helium is explained by the observed greater anode potential drop and consequently greater sheath thickness.

This paper presents an optical modification of the method of wireless byte-by-byte transmission of a digital signal multiplexed by the value of the orbital angular momentum (OAM) of an electromagnetic wave. This method was previously applied to radio signals. The transmitter is made as a circular array of coherent laser beams formed by splitting the original laser radiation into eight channels with different OAM values. The wave field propagates in space and comes to the input of the receiving telescope, and a sorter of OAM modes is used to demultiplex the signal. The combining of eight laser beams in the comparator yields the complete structure of the transmitted digital signal. A conceptual design of the experimental setup implementing this method is proposed, and the possibility of its practical implementation is demonstrated through numerical simulation.

This paper delves into the problems of weight and size reduction and smoothing voltage and current waveforms of the power supplies for stand-alone objects. The aim of the present work is to design filters, providing permissible current and voltage ripple levels, within multilevel inverter structures. The backbone of the research consists in dividing the power flow into two components, namely, uncontrollable DC component and pulse controlled one. For this purpose, the two voltage source inverters were elaborated. One inverter is fully controlled with duty ratio from 0 to 1. Another one is controlled conventionally by 180-degree control algorithm, which creates uncontrollable DC component in the consumed current waveform. The methodology of conventional LC-filter design has been extended on the proposed circuit topology. This allowed reducing the voltage and current ripples and improving weight and size parameters for the input and output filters of the power supply. The proposed methodology will presumably show its applicability in calculating filter parameters for multilevel converters, employed in power supplies, connected to the load via long cables.