bluuebunny/crossref_metadata_2025 huggingface dataset:
Aglomerações Produtivas do setor canavieiro no mercado de trabalho formal: uma análise por microrregiões brasileiras (2019 a 2021)
Authors: Shikida Pery Francisco Assis , Oliveira Leandro José de , Pereira D'Arisbo Sandra Mara , Galante Valdir Antonio
Published: October 2024

O artigo analisou o potencial da geração de emprego formal no cultivo de cana-de-açúcar nas microrregiões dos estados de Minas Gerais, São Paulo, Paraná, Mato Grosso do Sul e Goiás (2019 a 2021). O Índice de Concentração Normalizado (ICN) foi estimado a partir do Quociente Locacional, do índice Hirschman-Herfindahl e do índice de Participação Relativa. O constructo para verificar padrões de concentração ou dispersão espacial no setor foi elaborado por meio de informações sobre vínculo formal obtidas junto a RAIS. Os dados mostram que em 2019, das 156 microrregiões pesquisadas, 38 apresentaram adensamento mínimo, representando 84,58% dos vínculos no setor canavieiro. Desse total, 34 microrregiões foram caracterizadas como sendo especializadas (ICN>1). Em 2020, 38 microrregiões indicaram adensamento mínimo, representando 83,94% dos vínculos alocados no setor, e dessas, 34 apresentaram índice acima de um, sendo consideradas especializadas no emprego de mão de obra para o cultivo de cana-de-açúcar. De forma análoga aos anos anteriores, 38 microrregiões apresentaram adensamento mínimo em 2021, o que representou 84% dos vínculos alocados no setor, sendo que dessas microrregiões 34 foram consideradas especializadas, com índice acima de uma unidade. As microrregiões com maior aglomeração especializada no emprego de mão de obra formal do setor canavieiro se encontram no Estado de São Paulo.
Etnobiología y cambio climático en humedales marinos del sur de Chile
Authors: Cursach Jaime , Araos Francisco , Valencia Carola , Ruz Daniela , Barrientos Moisés , Delgado Claudio
Published: October 2024

Objetivo: el objetivo de este trabajo es estudiar la etnobiología de dos humedales marinos del sur de Chile, identificando indicadores locales de impacto del cambio climático, mediante el análisis del conocimiento ecológico local. Se trabajó en los humedales marinos de Coihuín y de Maullín, ubicados en la Provincia de Llanquihue, Región de Los Lagos, sur de Chile. Ambos lugares son sitios de importancia para la conservación de aves playeras migratorias. Metodología: entre noviembre del 2022 y marzo 2023, se realizaron 35 entrevistas semiestructuradas a personas que habitan y utilizan estos humedales marinos. Los resultados indican que la principal actividad laboral es la recolección de orilla (de algas y mariscos) y cultivo del alga Pelillo (Agarophyton chilense). Conclusiones: existe un importante conocimiento ecológico local de las comunidades litorales que habitan los humedales marinos estudiados. Se identificó un total de 24 especies de plantas, algas y animales reconocidos localmente por sus propiedades medicinales. Por otra parte, se identificó un total de 38 indicadores locales de impacto del cambio climático. Se discute la vulnerabilidad social ante la necesidad de afrontar/adaptarse a los cambios ambientales, las sugerencias locales y futuras líneas de investigación.
A review of ectoparasites (Acari and Hirudinea) associated with herpetofauna in the Mexican Yucatan Peninsula
Authors: Phangurha Josh , Nahuat-Cervera Pedro E. , Theodorou Alexandros , Oakley Joseph , Sawoscianiki Olga , Barão-Nóbrega José António L.
Published: October 2024

Ectoparasites are common on herpetofauna and can cause skin lesions, thermoregulatory complications,and hinder growth. Herein we present records from the literature and new data from the Calakmul Biosphere Reserveon ectoparasites of herpetofauna in the subclasses Acari (mites and ticks) and Hirudinea (leeches) from the MexicanYucatan Peninsula. Our new records fill important gaps in our knowledge of reptiles and amphibians affected by ectoparasitesand the geographic distribution of these interactions in Mexico. We also discuss conservation implications ofrecording ectoparasites particularly for vulnerable reptilian species as well as anthropological health issues that couldarise with diminishing natural habitats causing these animals and their parasites to live closer to humans.
Absolute quantification of AAV genomes from total DNA with digital droplet PCR (ddPCR) v1
Authors: Michael Coughlin Gerard
Published: October 2024

Accurate and absolute determination of AAV transduction from total DNA is important for understanding gene transfer efficiency across multiple experimental manipulations. As compared to relative measurements (e.g. through comparison of qPCR CT values between experimental conditions), absolute quantification can provide biological insights (e.g. actual average MOIs) that can guide further development of these vectors. This protocol enables absolute measurement of AAV genome number from total DNA samples extracted from animal tissues. Because total DNA is extracted, it is possible to estimate the number of AAV genomes per cell, using DNA content per cell and an estimate of transduction efficiency.
Propagandistas de trinchera. Los desertores republicanos como agentes socializadores de los combatientes sublevados (1936-1939)
Authors: Leira-Castiñeira Francisco Jorge
Published: October 2024

Este artículo ofrece una interpretación centrada en el impacto de los desertores republicanos en la socialización de los combatientes sublevados y la posterior aceptación de la dictadura franquista. A diferencia de los Estados nación, no todos los desertores fueron enviados a prisión o campos de concentración; aquellos sin delitos de sangre fueron destinados al frente. El contacto entre los reclutas forzosos del bando insurgente y los evadidos pudo influir en su percepción del conflicto al descubrir que las realidades en ambos lados de las trincheras no diferían significativamente. A través de la teoría de los líderes de opinión, los desertores, de manera aparentemente banal, pudieron impactar en la heterogénea tropa sublevada con sus experiencias. Este estudio emplea la documentación obtenida del servicio de información insurgente, en concreto los interrogatorios, teniendo en cuenta las limitaciones de esta fuente. El texto trata de aportar otra mirada a la consolidación de la dictadura.
Uma aproximação à história e estado da psicanálise em Moçambique
Authors: Theiss-Abendroth Peter ,   Charité – Universitätsmedizin Berlin, Marinho Ney ,   Associação Brasileira de Psiquiatria, Fernandes Antónia ,   Instituto Politécnico de Setúbal, Syring Ralf ,   Frente de Libertação de Mocambique, Lustosa Bastos Rogério ,   Universidade Federal do Rio de Janeiro, Stubbe Hannes ,   Universität zu Köln, Yussuf Yumna ,   Ayamed, Moura Ana Cristina ,   Hospital Psiquiátrico São Pedro, Walte Joachim ,   Katholisches Kinderkrankenhaus Wilhelmstift, Efraime Júnior Boia ,   Universidade Pedagógica de Moçambique, Riedesser Peter ,   Hospital Universitario Hamburgo-Eppendorf, Yusuf Yanisa ,   Universidade Federal do Rio Grande do Sul
Published: October 2024

Este texto Uma aproximação à história e estado da psicanálise em Moçambique representa uma ocasião extraordinária e inusitada, dada a ligação que estabelece com o campo e o estado da psicanálise em Moçambique. Desta forma, permite aproximar-nos de um contexto com o qual o mundo acadêmico latino-americano geralmente mantém uma distância e um desconhecimento acentuados. No caso particular dos temas abordados neste livro a partir de uma diversidade de autores e abordagens, a necessidade de construir laços comunicativos com esses ambientes institucionais e acadêmicos torna-se mais necessária, considerando as coincidências em relação a muitos dos problemas abordados (conflito armado, trauma e violência, por exemplo). Esperamos, então, que esta publicação contribua para aprofundar este tipo de vínculos e permita aos leitores uma aproximação ao estado da psicanálise em Moçambique e às suas implicações para a prática clínica.
UHF antenna complex with polarization adaptation
Authors: Buzov A.L. , Bondar P.I. , Karlov A.V. , Minkin M.A. , Khairullin M.A.
Published: October 2024

Formulation of the problem. With the development of the telecommunications industry and the growth in the number of subscribers, there is a need to more efficiently use the microphone frequency resource and increase the capacity in the mid-frequency UHF network. Thus, a promising approach to the UHF antenna complex is polarization adaptation, which makes it possible to compensate for the negative influence of various objects on the propagation of paths, such as effects of influence, multipath, depolarization, etc. A model of an antenna complex with polarization adaptation has been developed. In this case, polarization adaptation by the image stabilization method selects the signal with the highest signal level corresponding to the polarization. A distinctive characteristic of this AFS is the controlled control of measurements of the received signal. The antenna complex is used for current and future VHF-UHF pair communications. The proposed antenna system makes it possible to effectively compensate for the effects of depolarization on radio wave propagation paths and increase the signal/(noise + interference) ratio, including in conditions of complex interference activity.
Small-sized active phased array antenna for base stations of mobile radio networks in limited deployment conditions
Authors: Buzova M.A. , Karlov Al.V. , Neshcheret A.M. , Naryshkin I.M. , Kurakov V.A.
Published: October 2024

Today, most telecommunications structures are oversaturated with antenna technology. There is a need to use high-rise buildings and facilities that are not equipped for communication. However, the use of such objects imposes a number of restrictions on the installation locations of antenna systems. Thus, the problem arises of developing an antenna system that makes it possible to achieve a circular radiation pattern using small-sized antennas. A model of a small-sized UHF AFAR has been developed. A distinctive feature of this AFAR is the use of a ring active phased antenna array with an electrically controlled radiation pattern as an antenna system. Such solutions have not been used in domestic antenna technology, including military radio communications. The antenna complex is proposed to be used for installation on mobile objects, as well as on the upper platforms of towers and masts to provide a circular radiation pattern in places where it is impossible to implement a ring antenna array around the perimeter of the object.
The influence of phase noise and nonlinear distortions of high-speed digital-to-analog converters on the parameters of digital communication systems
Authors: Yakimenko K.A. , Romashov V.V. , Khramov K.K. , Doktorov A.N. , Sochneva N.A.
Published: October 2024

Problem statement. The trend in modern microwave electronics to transfer analog functions to the digital domain has led to the emergence and active use of high-speed digital-to-analog converters (DACs) in special operating modes in promising communication systems. However, optimization of power consumption and economic costs of signal generators (for example, through the use of simplified clock generators or by saving FPGA memory) leads to an increase in phase noise and nonlinear distortions in the output signal, which has a significant impact on the parameters of the communication system. Goal. Evaluation of phase noise and nonlinear distortions of signal generators based on high-speed digital-to-analog converters, as well as the study of their effect on the parameters of a digital communication system. Results. Expressions for estimating the spectral power density of phase noise of a signal generator based on a high-speed DAC are proposed. It is determined that the level of phase noise of the shaper is mainly determined by the noise of the clock generator. The jitter of the communication system was evaluated when using a surfactant generator and a PLL-based synthesizer as a clock generator. A mathematical model of the output signal of the shaper is proposed, taking into account nonlinear distortions caused by sampling, phase code truncation and amplitude quantization. A model of a communication system with multi-position quadrature amplitude modulation has been developed to evaluate parameters taking into account phase noise and nonlinear distortion of the shaper based on high-speed DACs. It is determined that the intrinsic phase noise of the signal generator leads to an increase in the probability of bit error (by about an order of magnitude compared to ideal formers). The use of surfactant generators as clock generators makes it possible to reduce the probability of bit errors of the communication system by 3-5 times compared with PLL-based synthesizers. Practical significance. It is shown that the displacement of points in the signal constellation is mainly influenced by nonlinear distortions of the output signal of high-speed DACs caused by truncation of the phase code, as well as incomplete suppression of spectral components located in the neighboring Nyquist zone. The proposed mathematical apparatus makes it possible to determine the optimal frequency ratios in the structure of the shaper, at which the lowest values of the displacement of the constellation points are achieved.
Method for measuring radiation patterns of digital antenna arrays
Authors: Djigan V.I.
Published: October 2024

Formulation of the problem. The Digital Beamforming Antenna Arrays (DBAA) are widely used as the directional antennas in radio systems today. However, such arrays typically do not have a radiofrequency output. Consequently, the standard methods for measuring the Radiation Patterns (RP), based on the transmitting of a monochromatic probing signals, reception of the signals in the far field, as well as measuring the output power of the antenna array, cannot be used to measure the RP of the DBAA. The method considered in this work involves the transmitting a probing signal modulated by a pseudonoise sequence and processing the DBAA output signal at the zero intermediate frequency (base-band) using a matched filter or a correlator. Target. A method for measuring the radiation pattern of the DBAA is considered, based on the correlation processing of its output signal. Results. The paper presents a description of the setup for measuring the DBAA RP, as well as a mathematical explanation of the measurement procedure. It is shown that the accuracy of the RP measurement depends on the Signal-to-Noise Ratio (SNR) at the outputs of the receivers of the DBAA channels, and the number of array channels and the number of symbols of the pseudonoise sequence used for the modulation of the radiated signal. The error in the RP measurement decreases by 3 dB each time as the number of the DBAA channels or the number of symbols of the pseudonoise sequence used in the measurements is doubled. This result is confirmed by simulation the measurement of RP of the eight- and sixteen-channel linear DBAA using pseudo-noise sequences of maximum length (M-sequences) with a number of symbols equal to 1023 and 2047. Practical significance. The proposed method does not require the usage of the up-converter to convert the base-band DBAA output signal from the base-band to a carrier frequency, and it also does not require the usage of a power meter for measurement the analog signal at the output of this converter.
Sensitivity evaluation of optical receiver mixers
Authors: Bestugin A.R. , Pogorelov A.A. , Dvornikov S.V. , Dvornikov S.S. , Kirshina I.A.
Published: October 2024

In optical receivers for realisation of procedures of heterodyning of a signal, both at a stage of formation, and at reception, as a rule, diodes are used. At the same time diodes, being electronic devices, are characterised by internal noises, which limit the sensitivity of reception. The nature of internal noise of electronic devices is determined by thermal processes and shot effect, which in their turn are determined not only by the ambient background temperature, but also by the frequency of received radiations. To present the results of estimation of the threshold sensitivity of diode mixers in heterodyning paths of optical receivers. Results are presented on the development of an approach to sensitivity estimation of heterodyne receiver mixer estimation. Estimation expressions for calculating the internal noise level of an optical mixer are obtained. The approach of shot noise estimation characterising the threshold sensitivity from the position of noise temperature is proposed. Simplified expressions of dependence of threshold sensitivity as a function of radiation frequency at a given temperature are obtained. Noise values in terms of temperature for different frequencies are calculated. A practical method of measuring the noise temperature, which characterises the sensitivity of reception, based on measuring the output voltage when receiving signals from sources with known temperatures of emitters, is substantiated. The values of the signal-to-noise ratio of the threshold sensitivity for different frequency ranges are presented. The obtained analytical expressions allow us to conclude that the rational solution is the choice of the frequency range in the region of 0.1…1 THz, because it is characterised by a relatively low noise temperature, but at the same time it is able to provide a high speed of message transmission.
Determining the reliability of complex RES by through decomposition by lower and upper limit values
Authors: Antilikatorov A.B. , Filatov M.A. , Beletskaya S.Yu.
Published: October 2024

Formulation of the problem. Reliability modeling of complex systems can be greatly simplified by decomposition into its component elements. However, as the number of objects in complex systems increases, modeling and analyzing their reliability becomes more labor-intensive, even when using methods based on finite formulas. One reason for the complexity is the increasing number of possible states of the system. Target. To facilitate the process of calculating the reliability of complex radio-electronic systems, you can apply the method of calculating the lower and upper limit values of reliability indicators. Results. In the process of accurately calculating indicators for each possible state of the system, we can estimate the minimum and maximum values of these indicators. Practical significance. Estimation of the lower and upper values of reliability indicators allows present the range of values within which the real value of the reliability indicator lies. It helps to take into account a variety of factors, such as different operating conditions, variations in production process, statistical deviations and other variations in the system.
High-performance decoding using deep neural networks
Authors: Sviridova I.V. , Khoroshailova M.V. , Lyalin D.V.
Published: October 2024

Problem statement. Deep neural networks are successfully used in channel coding to improve the quality of decoding. However, modern neural channel decoders cannot achieve high decoding performance and low complexity at the same time. To overcome this problem, it is necessary to develop a decoder with a double residual neuron. By integrating residual input and residual learning into the neural channel decoder architecture, it will significantly improve decoding performance while maintaining low complexity. Goal. Development of a decoder architecture with a dual residual neural network, which provides high decoding performance in channel coding with low model complexity and computational costs. Results. The simulation results show that the proposed decoder with a double residual neural network provides a significant increase in decoding performance. Compared to a neural decoder based on a trust propagation algorithm, a decoder with a dual residual neural network provides an additional 0.5-1.8 dB encoding gain compared to different channel codes. Compared to the hypergraph neural decoder, which has the best error correction capability among all existing neural channel decoders, the dual residual neural network decoder also provides similar or even better decoding performance for different channel codes. Practical significance. The results obtained can be used to improve decoding efficiency and improve performance in channel coding. The work was carried out with the financial support of the Ministry of Science and Higher Education of the Russian Federation within the framework of the state assignment "youth laboratory" No. FZGM-2024-0003.
Development of a three-dimensional object scanner
Authors: Bezrukaviy A.M. , Bobylkin I.S. , Vanin V.A.
Published: October 2024

Problem statement. In the world of modern technology, three-dimensional modeling plays an important role in various fields, ranging from design and medicine to entertainment and virtual reality. Extensive mathematical support is required to create accurate and realistic three-dimensional models of objects. In turn, the mathematical support for a three–dimensional limb scanner is an important part that allows you to receive and process information about three-dimensional objects. Goal. To develop a working device relying on already existing formulas and algorithms developed by us that allow us to process external information and translate it into a three-dimensional virtual object. Practical significance. The results obtained can be used in the medical field, namely in traumatology and orthopedics, allowing the creation of printed samples of casts and prostheses.
Development and research of filter models communication and control systems configured for the required set of parameters
Authors: Pirogov A.A. , Turetskaya E.V. , Akishkin R.M.
Published: October 2024

Problem statement. A digital filter refers to a hardware or software implementation of a mathematical algorithm that converts a digital signal in a certain way. The classification of digital filters is usually based on the functional characteristics of digital filtering algorithms. Digital filters may have parameters that cannot be implemented in analog filters, do not require periodic monitoring and calibration, and one filter can process several input channels or signals, while the accuracy is limited only by the bit depth used. The implementation of digital signal processing units using programmable logic integrated circuits (FPGAs) will significantly simplify hardware costs and make the most effective use of these digital filter capabilities. Goal. Conducting research in the field of digital signal processing in order to obtain fundamentally new software and hardware architectures, developing an RTL model of a complex functional block (SF block) of a digital signal processing system, its verification both at the logical and physical level. Results. In the course of the scientific research, a software and hardware model of the filter was developed to adjust the parameters during operation, taking into account their architectural advantages and disadvantages. In order to verify and confirm the adequacy of the methodology developed in the course of the study, an SF model was created-a digital signal processing unit. This model has been implemented and physically verified on the basis of a debugging board using FPGAs. Practical significance. The technique presented in this paper will allow the development of software and hardware devices for digital signal processing, with the possibility of their configuration at the software level for the required set of processing parameters, which in turn will significantly save resources spent on development.
The method of choosing a coolant based on a numerical experiment
Authors: Tsipina N.V. , Samoilenko N.E. , Voronin D.R.
Published: October 2024

Formulation of the problem. When designing modern liquid cooling systems, the problem arises of optimizing the choice of the type of immersion liquid used for cooling at the same time as solving the problems of optimizing the position of fuel elements and the choice of housing material. Purpose. Creation of a methodology for the reasonable choice of the type of immersion fluid in the process of computer-aided design of cooling systems of thermal power plants based on the results of a numerical experiment in a software environment based on a quantitative assessment of the effect of topological optimization (optimization of the location of a heat-loaded element). Results. The possibility of increasing the efficiency of a liquid cooling system by using the proposed method for selecting the type of immersion liquid based on the results of a numerical experiment in a software environment based on a quantitative assessment of the effect of topological optimization (optimization of the location of a heat-loaded element) is shown. This estimate represents the temperature difference of the fuel element in its standard (central) and optimized (angular) position in the housing of the device under study. The use of a laboratory bench as an example ensured the successful verification of the results of the numerical experiment and the reliability of the conclusions based on it. Of particular interest is the setting and adjustment of the parameters used in the cooling system of liquids due to the lack of complete information about them in the literature and databases, as well as insufficient experience in the use of liquid cooling systems. As a result of the study, it was concluded that it is advisable to use various types of liquids. The results of computer modeling are presented, confirming the high efficiency of the presented technique. Practical significance. The obtained results can be used to improve the performance of liquid cooling systems by making an informed choice and optimizing the design parameters of a liquid cooling system.
Methodology for substantiating the parameters of navigation signals with double meander modulation for local navigation systems based on land pseudo-satellites
Authors: Filonenko V.V. , Mironov V.A. , Zhuravlev A.V. , Nerovny V.V.
Published: October 2024

Formulation of the problem. The development of local navigation systems based on land pseudo-satellites in order to solve the problem of insufficient noise immunity of global navigation satellite systems determines the relevance of the improvement of the theory of multicriteria synthesis of new types of navigation signals. Purpose. Ensuring high accuracy and continuity of navigation-time definitions with the level of out-of-band radiation reduced to compliance with electromagnetic compatibility requirements and an acceptable decrease in the energy efficiency of transmitters by developing a methodology for substantiating the parameters of navigation signals with double meander modulation for local navigation systems based on land pseudo-satellites. Results. The use of navigation signals with double meander modulation in local navigation systems based on land pseudo-satellites is proposed, and their advantages over currently used signals are shown. A methodology of multi-criteria substantiating of navigation signal parameters has been developed, taking into account spectral, correlation characteristics, as well as the effect of reducing the level of out-of-band radiation of land radio transmitting devices in order to ensure electromagnetic compatibility requirements on the time characteristics of the signal. Practical significance. The obtained results can be used by specialists in the field of local and global radio navigation systems when considering the introduction of new types of navigation signals that ensure high quality indicators of tracking their parameters, as well as the application of new and existing navigation signals in local navigation systems based on land pseudo-satellites.
Noise-resistant multi-frequency phase local radionavigation system based radio interference transmitters
Authors: Zhuravlev A.V. , Kiryushkin V.V. , Babusenko S.I. , Shuvaev I.V. , Markin V.G.
Published: October 2024

Formulation of the problem. The widespread use of electronic warfare has led to significant difficulties in the use of consumer navigation equipment (CNE) of global navigation satellite systems (GNSS). Local radio navigation systems, alternatives to GNSS, are characterized by low accuracy and low noise immunity. At the same time, a spatially distributed system of radio interference transmitters CNE GNSS, using wide-band multi-frequency BPSK signals, can be used to organize a noise-resistant LRNS, in which phase measurements will be used to increase the accuracy of measurements. Purpose. The purpose of this work is to justify the requirements for a local radio navigation system based on spatially distributed radio interference transmitters NAP GNSS, using the noise-resistant method of multi-frequency phase radio navigation. Results. An interference-resistant method of multi-frequency phase radio navigation is presented, and the requirements for a local radio navigation system based on this method are substantiated. For the given typical characteristics of NAP GNSS radio interference transmitters, the value of the frequency detuning of the spectral components of the multi-frequency signal was obtained, at which the best positioning accuracy is achieved. Practical significance. The results obtained can be used to organize a noise-resistant multi-frequency phase local radio navigation system based on NAP GNSS radio interference transmitters.
Measuring the amplitudes of the received symbols of the shift keyed radio signals
Authors: Chernoyarov O.V. , Glushkov A.N. , Chernoyarova E.V. , Litvinenko V.P. , Litvinenko Yu.V.
Published: October 2024

In high-speed discrete information transmission systems, multi-position signals with various types of phase and amplitude shift keying are widely used. There are multi-level amplitude shift keyed (ASK), amplitude and phase-shift keyed (APSK) and quadrature amplitude modulation (QAM) signals. When demodulating the amplitude code of such signals, the amplitude of the received symbol is determined, and its calibrated value is compared with the specified threshold levels. It is proposed to directly calculate the minimum and maximum amplitudes of the symbols at the output of the demodulator, with a subsequent definition of decision thresholds. It is noteworthy that there is no need to calibrate the amplitude characteristics of the reception path. The logarithmic ratio of the amplitudes of the received and previous symbols is further calculated. And if its value falls within the specified boundaries, independent of the signal and noise, then a decision is made about whether the amplitudes of these symbols belong to the maximum or minimum values. These obtained values are averaged after that and used to set thresholds for decision-making in the demodulator. The results of the statistical simulation confirm the high efficiency of the proposed technical solution.
Use of the Sub Array From Microstrip Elements in Dielectric Layers Before the Aperture of Phased Antenna Array for Impedance Matching at Scanning
Authors: Prilutskiy A. A.
Published: October 2024

The solution of an electrodynamics’ problem of radiation of the Phased antenna array (PAR), representing the infinite periodic structure generated from the open ends of waveguides is offered. Before an aerial aperture sub array from strip (tape) elements in the dielectric layers is installed. The array in the dielectric layers f organizes of strip-geometry elements artificial medium. The problem is reduced to system of the integrated equations of 1-st sort which is decided concerning unknown fields in the aperture of the open ends of waveguides and currents on stripe-geometry elements. In a wide frequency band the numerical analysis of radiation parameters artificial dielectric medium on PAR electrodynamics’ characteristics at beam steering.
Influence of parameter measurement errors on the three-dimensional radar image forming in a distributed radar consisting of a rotating receiving and stationary transmit-receive modules
Authors: Tatarsky B. G. , Tammam Najjar
Published: October 2024

The purpose of the article is to consider the influence of the accuracy of measuring the rotation parameters of the routing receiving antenna and observation conditions on the formation of 3D radar images using a distributed radar consisting of a rotating receiver, and a fixed stationary transceiver antenna. The article provides a detailed mathematical description of the process of calculating the standard deviation of the height measurement of the observed terrain depending on the next parameters: the slant range, the height of the radar carrier, the radius of rotation of the phase center of the receiving antenna, the vertical distance between the plane of rotation of the phase center of the receiving antenna and the phase center of the transceiver antenna, the phase of the signal at the output of the interferometer, and the angular position of the phase center for the receiving antenna. The impact of errors has been evaluated using mathematical modeling. The presented modeling results show that errors in measuring the rotation parameters and observation conditions lead to errors in the reconstruction of the topography of the observed area. In particular, errors in estimating the signal phase at the interferometer output have been studied; the results showed that the errors in estimating the height of the studied points on the Earth's surface can reach 1 m with signal-to-noise ratio (SNR) of 20 dB and more than 10 m at 5 dB. In addition, with a SNR of 5 dB, it has been observed a distortion of the reconstructed terrain and violation of its contrast. In this case, the standard deviation of the measurement of relief height significantly depends on the angular position of the phase center of the receiving antenna. In this regard, to ensure a minimum error in estimating the height of the earth's surface using the interferometric system implemented by a stationary transceiver module and the circularly rotating receiving module, it is necessary to correctly choose the time corresponding to the angle of rotation of the phase center receiving antenna.
Method of characteristic modes
Authors: Kudin V. P. , Fanyaev I. A.
Published: October 2024

In recent years, the number of works on the method of characteristic modes and problems solved with its help has increased significantly, which indicates an awareness of its potential and, in connection with this, a growing interest in this approach. The attractiveness of this method lies in the fact that it provides a clear physical picture of the occurring phenomena and the ensuing opportunity to build on this basis methods for creating structures with the required parameters and combating undesirable phenomena. Unfortunately, in the Russian-speaking segment of applied electrodynamics, very few researchers are engaged in the development and application of the approach under consideration. The purpose of this work is to increase the interest of Russian-speaking researchers in the method of characteristic modes. A review of publications devoted to the method of characteristic modes, both early, fundamental and already classic, associated with the names of R.J. Garbacz and R.F. Harrington, and those which have appeared in recent years and offer generalizations of the method for various electrodynamic structures, has been carried out. This includes composite structures consisting of a set of metal and dielectric bodies of various configurations. In addition, variants of the method for antenna arrays of both infinite periodic and finite sizes have been considered. Issues related to modal tracking problems, orthogonal properties of characteristic modes and improving the convergence of solutions have been considered. Much attention is paid to works containing solutions to specific practical electrodynamic problems using the method of characteristic modes. The works have been shown, in which simple and effective approaches based on the method of characteristic modes are given for the design of a ship's HF antenna system, on-board aircraft antennas in the short-wave region, antennas placed on the platform of a battle tank, and the concept of designing an antenna for an electrically small-unmanned aerial vehicle has been presented. Options for solving the problem of reducing the mutual coupling of elements in antenna arrays have been shown. Attention is paid to MIMO antennas, antennas for smartphones, systems with specified radiation zeros, antennas using metasurfaces. According to the authors, the characteristic mode method, taking into account the increasing possibilities of its application, will make it possible to take the next step in the development, analysis or synthesis of new antenna structures that meet ever-increasing modern requirements.
Phase noise of signal generators with multichannel digital synthesizers
Authors: Korolev A. V.
Published: October 2024

Wide use of a direct digital synthesizer (DDS) and digital to analog converters (DAC) in digital antenna arrays permits for fast modulation parameters variations and beam positioning, and also improves the quality of beam forming due to high accuracy of signal generation. However, any systematic and random phase deviations of array channels not only lead to distortion of radiation pattern but also cause deterioration of signal processing at receiver end. Phase noise is one of critical parameters of such systems. Traditional theory and empirical methods assumes small or zero phase deviation of phase of channel output signal when combining these signals. We have proposed the model in which coupling of AM and PM noise persists for any arbitrary phase deviation of channels in multistage circuits comprising multichannel digital synthesizers. Absolute phase noise measurements of combined DACs outputs for zero phase offset and antiphase modes with two values of DAC output signal amplitude difference permit for estimation of residual phase noise of DAC and clock receiving and distribution circuitry and demonstrate good compliance of results of calculation.
Justification of the criterion for technical synthesis of radar complexes for covert airspace control
Authors: Knysh M. V. , Razinkov S. N.
Published: October 2024

For covert control of airspace, it is required to use complexes that meet the requirements for the effectiveness of obtaining data on objects in the field of observations and protection against the detection of their own unmasking signs by means of radio technical monitoring with predetermined indicators of resource intensity and efficiency of performing target functions. Joint fulfillment of these requirements when the parameters of the equipment structures and information processes are found under the established conditions for monitoring the properties of resource intensity and efficiency is achieved. Due to the complexity and inconsistency of the dependent bridges of the performance indicators and the stealth of application from the technical characteristics of the radar systems, it is necessary to substantiate the synthesis criterion for finding compromise technical solutions for the design of the equipment and the choice of a strategy for obtaining data on air facilities. The goal of the article is determination of design characteristics, frequency-time and energy signals parameters of radar complexes for analysis of air situation at concealment of unmasking features from means of radio technical monitoring. The criterion of technical synthesis of radar complexes for covert control of air-space is justified, which allows obtaining information about air objects at pre-established risks of threats to identify their own unmasking signs by means of radio technical monitoring. Regularities have been investigated and the conditions for achieving the target functions of complexes with resonant, band and frequency-independent signal transmission-reception devices have been determined. The principles of construction have been substantiated and the rules for finding rational parameters of the design of radar complexes and information processes used in airspace control in order to achieve the required operational properties of obtaining information about air objects while maintaining secrecy from radio monitoring facilities have been determined.
Patch antenna mutual coupling reduction using a genetic algorithm
Authors: Migalin M. M. , Obukhovets V. A.
Published: October 2024

Many modern telecommunication systems use antenna arrays for beamforming, and data rates increase. Mutual coupling between antennas negatively affects such systems' performance, so reducing the mutual coupling is a relevant research topic. This paper aims to cover a program development for the automated synthesis of decoupling structures between printed radiators. The results of the synthesis of printed structures for the reduction of mutual coupling between microstrip antennas placed on one dielectric substrate have been presented. Several structures that reduce the mutual coupling between antenna elements have been designed using a genetic algorithm. The developed program allows decoupling structure synthesis automation using numerical modelling methods. While synthesizing the decoupling structures, the directional properties of the received two-element antenna arrays have been considered.
Influence of the relative position of the Parus-A ionosonde antennas on the results of oblique sounding
Authors: Litvinov S. V. , Panshin E. A. , Skripachev V. O. , Starikovsky A. I.
Published: October 2024

The article considers the issue of relevance of ground-based equipment for ionosphere sounding and investigates some parameters of the ionospheric network of Roshydromet, equipped with Russian ionosondes “Parus-A”. The analysis of antenna systems used in these ionosondes has been carried out. The peculiarities of the reception of oblique sounding signals depending on the mutual arrangement of the antennas have been analyzed. A proposal has been made to take these issues into account in the development of new domestic ionosondes.
Model for describing mivar networks in the format of bipartite and tripartite oriented graphs for decision-making and information processing in machine-building AI
Authors: Kotsenko A.A. , Goryachkin B.S. , Bazanova A.G. , Marushchenko A.V. , Varlamov O.O.
Published: October 2024

Nowadays, there is a strong trend towards the creation of autonomous systems. For their development, it is required to make decision-making systems, which in this article are proposed to be implemented using mivar technologies of logical artificial intelligence. The paper considers the problem of choosing a specific implementation of the mivar approach using the example of bipartite and threadbare oriented graphs of mivar networks. Purpose – to give an example of activation of parameters and rules when solving the problem of route planning in a two-dimensional logical space. To consider the features of the subject area of automated process control systems and analyze three-sided graphs for decision-making and information processing in mechanical engineering. New ways of developing mivar networks based on three-sided and multi-sided graphs are considered for the implementation of the rules for choosing the type "if ..., then ..., else ...", in which some parameters can be filled in when the condition is met, and others when the condition is not met. The approach described in the paper to the creation of decision-making systems based on mivar technologies allows to achieve a higher degree of autonomy in order to further replace the role of a human operator in automated process control systems in production.
Efficacy assessment of strategies for mechanical univentricular circulatory support
Authors: Rubtsova E.N. , Pugovkin A.A. , Koroteev A.V. , Telyshev D.V.
Published: October 2024

Univentricular palliation is performed in patients with congenital heart defects, such as single functional ventricle, hypoplasia, septal defects, valve defects, obstructive defects, etc. After the palliation, the single ventricle becomes systemic, and venae cavae are directly or indirectly connected to pulmonary arteries. Palliated patients may temporary lead a full life yet eventually need heart transplantation. Mechanical circulatory support (MCS) may be an alternative treatment for heart transplantation in patients having univentricular circulation. Personalized modeling of a biotechnical MCS system allows to forecast current and optimal system states and assess support advisability and efficacy before implanting a circulatory assist device. In this study, a mathematical model of univentricular circulation with possibility to connect a circulatory assist device is presented. An algorithm for efficacy forecast and assessment of personalized mechanical univenricular circulatory support was developed. The algorithm automatically determines circulatory model parameters based on patient’s hemodynamic data and a set of parameter templates for corresponding age groups and circulatory states. This first stage is based on genetic algorithm with model parameters used as a genotype. Criterion of obtaining personalized model parameters is a zero sum of relative deviations of patient’s hemodynamic data and simulated data after personalization given the acceptable ranges of deviations determined based on accuracy of clinical diagnostic devices. At the second stage, the developed algorithm simulates a personalized biotechnical system of mechanical univentricular circulatory support using personalized circulatory model and pressure head–flow rate characteristics of circulatory assist device. At the third stage, the algorithm assesses advisability of chosen control strategy with negative recommendation for inadvisable strategy. At the last stage, the algorithm forecasts optimal states of biotechnical system determined as sufficiently approximate to normal circulation. Verification of the developed algorithm was performed with patients’ hemodynamic data from literature. Distributions of hemodynamic parameters in simulated biotechnical systems for three patients are described along with forecast optimal states and corresponding values of control parameter for chosen methods of support. In these cases, pediatric rotary blood pump previously developed by our research group was used as circulatory assist device. Assessment of changes in biotechnical system after implantation of circulatory assist device revealed inefficacy of MCS in one of three considered patients.
Radio sources location determination by the difference-range measuring method based on swarm intelligence
Authors: Semenyuk S.S. , Kablukov A.V. , Grigorov A.S.
Published: October 2024

The solution of the location determining problem by the difference-range measuring method in most cases boils down to finding the extremums of functions using various modifications of the gradient optimization method, which has a number of disadvantages, including the need to specify the first approximation of the coordinates of the source, the dependence of the solution of the system of equations on this approximation, as well as the potential possibility of finding a local extremum, instead of a global one. Because of this, there is a need to use global optimization methods that do not have these disadvantages. One of such methods is a heuristic method based on the intelligence of a swarm of particles. The article presents the results of research on the possibility of using swarm intelligence to solve the problem of determining the location of radio sources by the difference-rangefinder method. An analytical description of the method of global optimization of functions based on the intelligence of a "swarm" of particles is presented. The objective function of coordinates of radio emission sources is formed in relation to the difference-rangefinder method of location determination using the Mahalanobis metric. The results of solving the problem of determining the coordinates of radio emission sources based on the search for the minimum of the formed objective function by the "swarm" of particles are presented. The obtained results can be used in the development of mathematical models and software and hardware complexes for determining the location of radio sources by the difference-rangefinder method.