2304-9782, 2618-8686, 2405-7223 18 1 2025 1-203

SCO RUS 9-17 Blagoveschensk State Pedagogical University Baryshnikov Sergey svbar2003@list.ru Blagoveshchensk State Pedagogical University Milinskiy Alexey a.milinskiy@mail.ru Amur State University Stukova Elena lenast@bk.ru 0009-0004-6095-9026 Blagoveshchensk State Pedagogical University Lvov Andrey andrei.1998.lvov@gmail.com Dielectric properties of composites based on triglycine sulfate and barium titanate nanoparticles In the paper, the results of investigations in dielectric properties of composites (TGS)1−x/(BaTiO3)x with x = 0.10 and 0.20 have been presented. The composites were prepared by mixing TGS powders with BaTiO3 nanoparticles (3−5 μm and 400 nm in size, relatively). The sample surfaces were examined by electron microscopy, the temperature dependencies of permittivity of the subjects of investigation were studied. To control the effective spontaneous polarization of the samples, their pyroelectric effect was measured. In order to do it, the samples were previously polarized at room temperature. In heating, for composite samples, an increase ΔТс ≈ 3 deg.C in the Curie temperature was revealed for TGS contained in the composites, a rise in the permittivity of composites and a decrease in the tangent of their dielectric loss angle compared with pure TGS samples. The appearance of temperature hysteresis and blurring of the TGS phase transition taking place in the composites was detected. 10.18721/JPM.18101 537.226 triglycine sulfate composite dielectric constant nanoparticles barium titanate phase transition https://physmath.spbstu.ru/article/2025.78.1/ 01_9-17_18(1)2025.pdf

RAR RUS 18-29 0000-0002-6308-733X Peter the Great St. Petersburg Polytechnic University Kolesnik Elizaveta kolesnik_ev@mail.ru 0000-0003-1442-4886 Peter the Great St. Petersburg Polytechnic University Babich Elena E-5484-2014 56020596900 Peter the Great St. Petersburg Polytechnic University Smirnov Evgeny aero@phmf.spbstu.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

A supersonic viscous gas flow past a blunt cylindrical body bounded at its ends by parallel plates The paper presents the results of calculations of a supersonic laminar flow past a cylindrical body located between parallel horizontal walls (plates). The free-stream Mach number M = 5. Calculations were carried out for various values of the geometric factor χ defined as the ratio of the distance between the walls to the blunt diameter of the leading edge of the body, the ratio varying from 2 to infinity. Decreasing the distance between the walls was shown to lead to a shift of the separated shock closer to the streamlined body, and to an increase in the thickness of the separation region. In the case of χ = 2 a nonstationary self-oscillatory flow regime characterized by strong oscillations of the separated shock wave was realized. 10.18721/JPM.18102 519.6:533.6.011 high-speed flow numerical simulation internal separated flow viscous-inviscid interaction horseshoe vortex https://physmath.spbstu.ru/article/2025.78.2/ 02_18-29_18(1)2025.pdf

RAR RUS 30-41 0000-0002-2775-9864 Peter the Great St. Petersburg Polytechnic University Garbaruk Andrei agarbaruk@mail.ru 0000-0001-9473-7430 Peter the Great St. Petersburg Polytechnic University Golubkov Valentin golubkovvd@gmail.com

St. Petersburg, Russian Federation

Peter the Great St. Petersburg Polytechnic University Strelets Michael strelets@mail.rcom.ru

St. Petersburg, Russian Federation

The influence of pressure gradient and local surface irregularities on the laminar-turbulent transition in the boundary layer The paper presents the results of a computational study of the effect of the longitudinal pressure gradient (PG) on the position of the laminar-turbulent transition (LTT) in the boundary layer on a smooth plate and on a plate with local surface irregularity. For a smooth plate, the calculations were performed using both the method developed by the authors, based on the Global Stability Analysis (GSA) of the laminar boundary layer, and other known methods that take into account the LTT. The results obtained varied significantly for different methods and differed from the more reliable GSA results, which questions the accuracy of these methods. The studies have proved that it is possible to perform a total evaluation of the LTT position shift by adding the shift for a smooth plate due to changes in the PG value and the shift for a plate with irregularity on its surface in the absence of PG. 10.18721/JPM.18103 532.5.013.4 Tollmien-Schlichting waves global stability analysis laminar-turbulent transition longitudinal pressure gradient surface irregularities https://physmath.spbstu.ru/article/2025.78.3/ 03_30-41_18(1)2025.pdf

RAR RUS 42-57 0000-0001-7011-6197 Peter the Great St. Petersburg Polytechnic University Stabnikov Andrey an.stabnikov@gmail.com 0000-0002-2775-9864 Peter the Great St. Petersburg Polytechnic University Garbaruk Andrei agarbaruk@mail.ru Computation of flows around stationary and rotating cylinders and a tandem of cylinders at near-critical regimes using DDES coupled with a laminar-turbulent transition model The objective of this paper is to assess the capabilities of a hybrid RANS-LES approach DDES coupled with algebraic RANS turbulence transition models SST KD and SST alg-γ, allowing the prediction of the laminar-turbulent transition (LTT). The approach is applied to calculations of flows around stationary and rotating cylinders as well as a tandem of stationary cylinders. It is shown that for the simulations of the flows under consideration, this approach significantly outperforms the standard SST DDES (within the standard SST DDES it is assumed that the flow is completely turbulent, and the LTT is not taken into account). At the same time, the obtained computational results depend significantly on the choice of the LTT model, and neither of the two models has a clear advantage in terms of agreement between the computational results and experimental data. 10.18721/JPM.18104 532.517.4 turbulence global hybrid RANS/LES approaches DDES drag crisis Magnus effect https://physmath.spbstu.ru/article/2025.78.4/ 04_42-57_18(1)2025.pdf

RAR RUS 58-68 “B. E. Vedeneev VNIIG”, JSC Andrianova Elena elena-andrianova@bk.ru 0000-0002-9249-2158 Peter the Great St. Petersburg Polytechnic University Boldyrev Yury boldyrev@phmf.spbstu.ru Features of using the main criterion of the FDD method in identifying the dynamic characteristics of structures This publication continues the series of articles devoted to the Frequency Domain Decomposition (FDD) method that serves to identify the dynamic characteristics of structures (natural frequencies and forms of natural vibrations) from the vibration tests data without using vibroexcitation. The method is based on the SV-decomposition of the cross-spectral density matrix (CSDM) of the measured signals. The proof of the possibility of using the FDD for an incomplete CSDM was given, such matrices being typical when working with large-sized structures. In this case, vibration tests include two types of measurements: continuous long-term ones taking at one or more selected reference points and consecutive short ones at other measuring points. The presented results may be useful in the operation of large concrete dams and other hydraulic structures to identify their dynamic characteristics. 10.18721/JPM.18105 51-74 decomposition in frequency domain dynamic characteristics matrix of mutual spectral densities https://physmath.spbstu.ru/article/2025.78.5/ 05_58-68_18(1)2025.pdf

RAR RUS 69-86 0000-0002-3972-9259 Northern Water Problems Institute of Karelian Research Centre of RAS Smirnov Sergei sergeysmirnov92@mail.ru 0000-0001-7608-7120 Peter the Great St. Petersburg Polytechnic University Smirnovsky Alexander smirta@mail.ru 0000-0003-4150-2712 Northern Water Problems Institute of Karelian Research Centre of RAS Bogdanov Sergey 0000-0003-2726-0104 Northern Water Problems Institute of Karelian Research Centre of RAS Zdorovennova Galina 0000-0003-0313-6731 Northern Water Problems Institute of Karelian Research Centre of RAS Efremova Tatiana efremova@nwpi.krc.karelia.ru 0000-0003-1540-3788 Northern Water Problems Institute of Karelian Research Centre of RAS Palshin Nikolay 0000-0003-1695-4872 Northern Water Problems Institute of Karelian Research Centre of RAS Zdorovennov Roman Numerical simulation of under-ice radiatively driven convection in lakes with different water transparency In the paper, the results of eddy-resolving numerical simulation of convection generated by inhomogeneous heating of water column by solar radiation in an ice-covered shallow lake (the factor of wind impact on the water surface is excluded). The calculations have been performed using the Implicit LES method for different values of the extinction coefficient, which defines the degree of attenuation of solar radiation in the water column. An analysis of the three-dimensional flow structure, the time evolution of temperature and velocity pulsations was carried out, and the increments of the lower boundary and the temperature of the convective mixed layer were calculated depending on the incoming heat. The results obtained shed light upon the nature of the processes occurring in the type of lakes under consideration, in particular, to identify the influence of water transparency on the convective mixing process. 10.18721/JPM.18106 556.555.4/.5; 556.556 radiatively-driven under-ice convection water transparency turbulent velocity pulsations Implicit LES https://physmath.spbstu.ru/article/2025.78.6/ 06_69-86_18(1)2025.pdf

RAR RUS 87-93 Al-Wataniya Private University Nassif Alaa alaa.nassif@wpu.edu.sy

Al-Wataniya Private University, International Hama‒Homs‎ Highway, Hama, XQ92+PMC, Syria

University Homs Sahyouni Walid wsahyouni@homs-univ.edu.sy

Homs University, Homs, PP75+5VC, Syria

University Homs Zeidan Ola ozedan@homs-univ.edu.sy

Homs, PP75+5VC, Syria

The effect of a gas type on the soft X-ray yield from a plasma focus Using the Lee code version (RADPFV5.15de), we carried out a series of numerical ‎experiments to find the parameters for the plasma focus and the soft X-ray yield for each of ‎nitrogen gas (molecular) and neon gas (atomic) within an appropriate temperature range for ‎PF400 dense plasma focus device. The results showed that the highest value of the soft X-ray ‎yield in neon was 0.148 J at 3.2 Torr pressure, while for nitrogen it was 0.0634 J at 4.4 Torr. This is ‎because of the higher atomic number and effective charge of neon as compared to nitrogen. 10.18721/JPM.18107 533.9.03 plasma pinch PF400 plasma focus device soft X-ray yield Lee model https://physmath.spbstu.ru/article/2025.78.7/

RAR RUS 94-102 0000-0002-6210-4003 Peter the Great St. Petersburg Polytechnic University Ermak Sergey 0000-0003-0346-8349 Peter the Great St. Petersburg Polytechnic University Semenov Vladimir vladimir_semenov@mail.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

0009-0005-8838-6845 Peter the Great St. Petersburg Polytechnic University Sergeeva Maria A method for measuring the direction of the geomagnetic field to correct of the onboard rubidium atomic clock frequency using an Mz-magnetometer The article presents a method developed by the authors for measuring the direction of a magnetic field using an MZ-type quantum magnetometer, the readings of which are used to correct the frequency of an onboard small-sized rubidium atomic clock. The method was tested on a specially created experimental setup implementing an MZ-type quantum magnetometer with optical pumping. High sensitivity of the method to a change in the angle between the optical axis of the magnetometer and the direction of the magnetic field under study for small angles was found. A conclusion was made about the applicability of the developed method for various angles limited in magnitude by the presence of "dead zones" of the quantum magnetometer. 10.18721/JPM.18108 53.098 magnetic field optically pumped quantum magnetometer atomic clock magnetic shield https://physmath.spbstu.ru/article/2025.78.8/ 08_94-102_18(1)2025.pdf

RAR RUS 103-110 0000-0001-5219-6744 Peter the Great St. Petersburg Polytechnic University Taradaev Evgeniy Sominski Gennadiy sominski@rphf.spbstu.ru 0000-0001-5548-7379 Peter the Great St. Petersburg Polytechnic University Taradaev Sergei 0000-0001-5790-7197 JSC "Central reseach institute for materials" Gordeev Sergey Formation of an electron beam by an electron-optical system using a composite field emitter made of thermally expanded graphite and a mixture of thermally expanded graphite with diamond granules In the paper, the characteristics of electron flows formed by an electron-optical system with composite field emitters, made from thermally expanded graphite or a mixture of such graphite with diamond granules have been studied. These cathodes were developed at the Saint Petersburg Polytechnic University and the Central Research Institute of Materials. A distinguishing feature of these cathodes is their improved geometry. The maximum achievable emission currents, as well as the longitudinal and transverse components of the velocity of emitted electrons in the electron flow, were determined. The measurements were carried out in pulsed and continuous operations. Experiments showed that these types of cathodes provided emission currents up to 30 mA and operated stably under technical vacuum conditions. 10.18721/JPM.18109 537.533 field emission composite cathodes thermally expanded graphite electron-optical system electron beam https://physmath.spbstu.ru/article/2025.78.9/ 09_103-110_18(1)2025.pdf

REV RUS 111-128 0000-0001-5582-1111 The S. M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation Ivchenko Evgeniy 0000-0002-1584-1748 The S. M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation Golovko Konstantin 0000-0002-4823-0695 The S. M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation Ivankova Elena ivelen@mail.ru 0000-0002-3457-4788 The S. M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation Sokolova Margarita 55263592100 0000-0002-0161-5977 The S. M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation Glushakov Ruslan Application of electron microscopy techniques in experimental and clinical medicine This review has summarized the currently available literary information on the possibilities of applying the electron microscopy (EM) in experimental, clinical medicine and in related scientific fields. Concrete results that highlight the role of using EM in highly specialized clinical practice, where ultrastructural studies both complement routine light-optical methods and are their alternative has been presented. Examples of relevant data on virology, toxicology, nephrology, ophthalmology, neuropharmacology, forensic medicine, military and reproductive medicine have been provided. In a number of cases, the results achieved by EM were unique and capable of accurately describing the typical features of certain organs and cells. EM methods are indispensable for identifying, clarifying and recognizing various rare combined defects and pathologies, as well as for investigating the pathogenesis of viral infections and the mechanism of action of drugs. 10.18721/JPM.18110 616; 537.533.35 electron microscopy virology gynecology. andrology nephrology orthopedics ophthalmology cardiology neurophysiology https://physmath.spbstu.ru/article/2025.78.10/ 10_111-128_18(1)2025.pdf

RAR RUS 129-141 0000-0003-0309-5917 Peter the Great St. Petersburg Polytechnic University Berdnikov Yaroslav berdnikov@spbstu.ru 0000-0003-3298-3702 Peter the Great St. Petersburg Polytechnic University Ivanishchev Dmitry ivanishchev_da@pnpi.nrcki.ru 0000-0002-3395-0454 Peter the Great St. Petersburg Polytechnic University Kotov Dmitry dmitriy.kotov@gmail.com 0009-0001-9974-0169 Peter the Great St. Petersburg Polytechnic University Malaev Mikhail mmalayev@gmail.com 0009-0007-9874-9819 Petersburg Nuclear Physics Institute named by B. P. Konstantinov of NRC «Kurchatov Institute» Riabov Andrei andrei.riabov@cern.ch Feasibility to measure the properties of φ(1020) meson in collisions of bismuth nuclei at an energy of 9.2 GeV in the NICA collider using the MPD experimental setup We report results on a feasibility study of measuring the properties of φ (1020) resonance in collisions of bismuth nuclei at an energy of 9.2 GeV using the MPD detector at the NICA collider. Model calculations of heavy nuclei collisions and the secondary particles – the MPD material interaction have been performed for the φ(1020) → K+ + K– decay. The dependencies of the process’es key parameters on the transverse momentum for different intervals of centrality of bismuth nuclei collisions were obtained in the rapidity range from –0.5 to +0.5. The evaluations of the mass resolution, detection efficiency of the MPD detector and the transverse momentum spectra for the φ(1020) resonance were made. The sample size of bismuth nuclei collision data that allowed the φ(1020) resonance properties to be reconstructed with a sufficiently good accuracy to conduct a study of the φ(1020) meson production was estimated. 10.18721/JPM.18111 539.126.3 bismuth nuclei collisions production meson NICA collider MPD detector https://physmath.spbstu.ru/article/2025.78.11/ 11_129-141_18(1)2025.pdf

RAR RUS 142-148 0000-0002-8910-4775 Peter the Great St. Petersburg Polytechnic University Lobanov Andrey lobanov2.aa@edu.spbstu.ru 0000-0003-0309-5917 Peter the Great St. Petersburg Polytechnic University Berdnikov Yaroslav berdnikov@spbstu.ru Direct photon asymmetries in the longitudinally polarized proton-proton collisions at an energy of 27 GeV In this paper, we explore the potential of the generative-adversarial network (GAN) in order to predict the production of direct photons in the collision of unpolarized or longitudinally polarized protons at an energy of √s = 27 GeV. Our findings demonstrate that the GAN has been established to be capable of accurately reproducing the distributions of the physical characteristics of the produced direct photons. Moreover, the possibility to calculate the double longitudinal spin asymmetry of ALL was shown taking the values predicted by the GAN as a basis. 10.18721/JPM.18112 539.12 asymmetry direct photons neural network generative-adversarial network https://physmath.spbstu.ru/article/2025.78.12/ 12_142-148_18(1)2025.pdf

RAR RUS 149-162 0000-0003-0082-1856 Moscow Aviation Institute (National Research University) Serdyuk Dmitry 0000-0002-2653-6378 Moscow Aviation Institute (National Research University) Zemskov Andrei 0009-0006-4382-3244 Moscow Aviation Institute (National Research University) Ershova Alena Transient dynamics of an anisotropic Chow plate connected to an elastic-inertial base In the paper, the unsteady dynamics of a thin elastic anisotropic unbounded Chow plate mounted on an elastic-inertial base has been studied. An anisotropy model where the elastic medium had one plane of symmetry geometrically coinciding with the median plane of the plate was considered. The base was specified by its stiffness coefficient and mass one. The problem statement included equations of motion in displacements, initial conditions and those of infinity. The solution of the problem was constructed using the method of fundamental solutions and integral Fourier transforms in spatial coordinates and Laplace ones in time. The Fourier originals were found numerically using the method of integrating rapidly oscillating functions. An example of the calculation was given. 10.18721/JPM.18113 539.3 fundamental solution anisotropic material Chow plate transient waves integral transformation https://physmath.spbstu.ru/article/2025.78.13/ 13_149-162_18(1)2025.pdf

RAR RUS 163-181 Saint-Petersburg State University of Aerospace Instrumentation Pichugin Yuri yury-pichugin@mail.ru

Russia, 190000, St. Petersburg, Bolshaya Morskaya St., 61

0000-0002-9224-8761 Saint-Petersburg State University of Aerospace Instrumentation Pichugina Nika A singular spectrum analysis: problems and solutions The paper has examined various aspects of the singular spectrum analysis (SSA) method. The original purpose of the method is to optimize harmonic (spectral) analysis of time series. A theoretical justification based on integral equations was given for the SSA. A solution to the problem of large dimensionality of the autocovariance matrix (AM) was proposed. A method for estimating the periods of AM eigenvectors considered as basis time functions (BTF) was put forward. The problems of repetitive frequencies and frequency overlaps in the BTF structure were discussed. Those overlaps could have lower or higher frequences than the main BTF one. A possibility of distortion of the BTF period estimate due to relatively high-frequency superpositions was noted. To solve this problem, a modification of SSA (SSA-HC) has been proposed, that allows for a more correct and effective solution to the main problem. The solutions to problems were supported by numerical examples. 10.18721/JPM.18114 519.2-519.6 singular spectrum analysis time series covariance estimation dimensionality problem repeated frequencies https://physmath.spbstu.ru/article/2025.78.14/ 14_163-181_18(1)2025.pdf

RAR RUS 182-200 0009-0005-9699-8497 Peter the Great St. Petersburg Polytechnic University Golovchenko Andrew golovchenko.ai@edu.spbstu.ru 0000-0001-5216-6588 Peter the Great St. Petersburg Polytechnic University Petrov Aleksandr petrov.av1@spbstu.ru 0000-0003-2083-8989 Peter the Great St. Petersburg Polytechnic University Temkina Valentina temkina_vs@spbstu.ru 0009-0007-4713-1293 Peter the Great St. Petersburg Polytechnic University Archelkov Arseniy arsarch11@gmail.com 0000-0003-2300-084X Concern CSRI Elektropribor, JSC Tsibinogina Marina 0000-0001-8448-2024 Peter the Great St. Petersburg Polytechnic University Kotov Oleg kotov@rphf.spbstu.ru A coherent double spectral method for measuring the parameters of single-mode optical fibers with strong linear birefringence In this work, a coherent spectral method for measuring the parameters of anisotropic optical fiber with taking into account polarization dispersion of refractive indices (RI) and possible angular mismatches of birefringence axes of the circuit optical elements has been analyzed thoroughly. Using the Jones matrix method, the measuring polarization interferometer was treated and the relationship between its characteristics and circuit parameters was obtained. The deviations of the axial angles from the optimal ones were shown to lead to a decrease in the contrast of the output interference signals and to the appearance of parasitic spectral components. Analytical expressions for the birefringence and beat length of polarization modes having regard to the RI dispersion, as well as for the spectral transfer function (STF) of the polarization interferometer and its Fourier image were derived. The features of the application of the described method for measuring the key parameters of three types of birefringent fibers were experimentally demonstrated. 10.18721/JPM.18115 535.5, 535-4, 535.012.2 polarization of light Jones vector polarization mode anisotropic light guide https://physmath.spbstu.ru/article/2025.78.15/ 15_182-200_18(1)2025.pdf