2304-9782, 2618-8686, 2405-7223 16 2 2023 1-163

RAR RUS 9-18 Amur State University Pavlov Aleksei katal75@yandex.ru Amur State University Stukova Elena lenast@bk.ru Blagoveschensk State Pedagogical University Baryshnikov Sergey svbar2003@list.ru Phase transitions of caesium nitrate embedded in nanoporous alumina films In order to make material with improved properties, nanocomposites based on nanoporous Al2O3 films (having different pore sizes) filled with ferroelectric, namely, caesium nitrate CsNO3, have been fabricated, and their electrophysical charactistics have been investigated. The film surfaces were tested by electron microscopy. Temperature dependences of the effective permittivity ε' and of the third harmonic coefficient were measured for the nanocomposites. The phase-transition points were determined by the maximum value of the dε'/dT derivative. The reduction in pore was found to lead to a decrease in the Curie temperature (by more than 30 K) and a phase transition blur. This phenomenon is associated with the influence of intrinsic size effects. 10.18721/JPM.16201 537.226.4 ferroelectric caesium nitrate permittivity phase transition nanocomposite https://physmath.spbstu.ru/article/2023.66.1/ 01_9-18_16(2)2023.pdf

RAR RUS 19-26 Azerbaijan State Oil and Industry University Gamzaev Khanlar xan.h@rambler.ru Azerbaijan State Oil and Industry University Gamzaeva Nusaba hemzeyevanusaba90@mail.ru Numerical identification of the chemical reaction rate constant in the ideal displacement model A chemical-technological process of a second-order reaction in a chemical reactor of an ideal displacement, described by a nonlinear partial differential equation of the first order has been considered. Within the framework of the proposed model, the inverse problem of determining the rate constant of a chemical reaction was defined. In this case, an additional condition was set regarding the reagent concentration at the outlet from the reactor. To solve the inverse problem, its discrete analogue was constructed and a special representation was proposed for solving the resulting system of linear algebraic equations. As a result, an explicit formula for determining the approximate value of the rate constant of a chemical reaction was obtained. The possibilities of the proposed numerical method were illustrated by numerical calculations on model problems. 10.18721/JPM.16202 681.5:519.63 chemical reactor of ideal displacement chemical reaction rate constant identification problem coefficient inverse problem https://physmath.spbstu.ru/article/2023.66.2/ 02_19-26_16(2)2023.pdf

RAR RUS 27-51 0000-0003-1457-8236 Peter the Great St. Petersburg Polytechnic University Ipatov Andrey andrei_ipatov@mail.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

0009-0001-5775-2276 Peter the Great St. Petersburg Polytechnic University Kupriianov Genrikh henryweis3@gmail.com The plasmon resonance in the cadmium selenide semiconductor nanocrystals with different doping types The effect of the type of doping (surface (I) or bulk (II) doping) on the character of the dipole plasmon mode in semiconductor CdSe nanocrystals has been studied. It was found that in case I (donors located on the surface of the nanocrystal) the collective mode had a rotational character and only the angular degrees of freedom were excited. On the contrary, in case II the charge of the dopant impurities was distributed throughout the system and plasmon excitation was the oscillation of delocalized charge carriers in the direction normal to the surface. It was shown that the position of the resonance line was determined not only by the concentration of free charges, but also by the character of their collective motion determining by the type of doping. 10.18721/JPM.16203 538.9 semiconductor nanocrystal cadmium selenide doping plasmon resonance multiparticle excitation https://physmath.spbstu.ru/article/2023.66.3/ 03_27-51_16(2)2023.pdf

RAR RUS 52-60 Institute for Analytical Instrumentation of the RAS Pomozov Timofey tim-kor@mail.ru Institute for Analytical Instrumentation of the RAS Muradymov Marat m.muradymov@gmail.com 0009-0003-8001-7469 Institute for Analytical Instrumentation of the RAS Tkach Egor egorka765@gmail.com The efficiency of a focusing system based on thin diaphragms in the ion source with a corona discharge In this work, a charged particle beam transport in an ion source with a corona discharge, the source being equipped with a focusing system based on thin diaphragms in the standing gas and at atmospheric pressure, has been studied experimentally. The efficiency of the ion beam transportation through the focusing system was shown to depend on the distance between the corona needle and the diaphragm system, on the potential difference between the diaphragms of the focusing system and on the value of the corona discharge current. The results of comparing the efficiency of the ion beam transport in the ion source with using the focusing system and without it are presented. The use of the focusing system allowed to increase several times the current entering the collector through the diaphragm of the smallest diameter, and to raise the current entering the plane of this diaphragm by an order of magnitude. 10.18721/JPM.16204 621.384.8 ion source mass spectrometer corona discharge focusing system ion transport https://physmath.spbstu.ru/article/2023.66.4/ 04_52-60_16(2)2023.pdf

RAR RUS 61-67 Shri Shivaji Science College, Amravati Nagpure Pankaj nagpurepa@yahoo.co.in

Shivaji Nagar, Morshi Road, Amravati, 444603, India

Shri Shivaji Science College, Amravati Kherde Nivedita niveditaholey@gmail.com

Shivaji Nagar, Morshi Road, Amravati, 444603, India

Shri Shivaji Science College, Amravati Barde Waman wamanbarde81@gmail.com

Shivaji Nagar, Morshi Road, Amravati, 444603, India

Synthesis and PL study of Sr3 (VO4 ) 2 :Eu3+ phosphor for W-LED application In the present paper, a single host phosphor for a white light emitting diode (W-LED) Sr3(VO4)2:Eu3+, prepared by the co-precipitation method and combustion one, has been reported. Formation of the compound was confirmed by studying the X-ray diffraction pattern. The photoluminescence (PL) properties were studied by fluorescence spectrophotometer F-7000. The Sr3(VO4)2:Eu3+ exhibited a broad emission band covering the entire visible region centered at 520 nm wavelength and a sharp peak at 613 nm, when excited by 350 nm. The excitation spectrum at 520 nm emission wavelength was found to be suitable for pc-W-LED application. 10.18721/JPM.16205 678.046.82 strontium vanadate co-precipitation combustion X-ray diffraction pattern photoluminescence spectroscopy W-LED https://physmath.spbstu.ru/article/2023.66.5/ 05_61-67_16(2)2023.pdf

RAR RUS 68-77 Peter the Great St. Petersburg Polytechnic University Tretyakov Artem tretartem@gmail.com E-4237-2014 12784708700 0000-0001-9050-4453 Peter the Great St. Petersburg Polytechnic University Kapralova Victoria kapralova2006@yandex.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

0000-0001-7579-7577 Institute of Macromolecular Compounds Sapurina Irina sapurina@mail.ru Peter the Great St. Petersburg Polytechnic University Sudar Nikolai sudar53@mail.ru Peter the Great St. Petersburg Polytechnic University Shishov Mikhail shv_misha@mail.ru Electric and thermoelectric properties of a coordination polymer based on phenazine ligands and silver The paper presents the results of an experimental study of the electric conductivity and thermoelectric properties of a new coordination polymer (CP) based on phenazine ligands (Phz) and silver (Ag) synthesized by a one-step method. This method produces phenazine by oxidative dimerization of aniline under the action of AgNO3 followed by release of metal nanoparticles and subsequent self-organization of Phz with excess AgNO3 into the CP. The used method of the Phz-Ag synthesis was found to make possible obtaining CP with conductivity of about 1300 S/cm commensurable with the modern record value for CPs. The obtained experimental data led to the conclusion that the studied CP Phz-Ag possesses a metallic type of conductivity. A physical mechanism of forming this property was put forward. 10.18721/JPM.16206 538.95 polymer composite nanocomposite thermal properties coordination polymer phenazine ligand https://physmath.spbstu.ru/article/2023.66.6/ 06_68-77_16(2)2023.pdf

RAR RUS 78-88 Tashkent State Technical University Bekpulatov Ilkhom bekpulatov85@rambler.ru

2 Universitetskaya St., Tashkent, 100095, Uzbekistan

Peter the Great St. Petersburg Polytechnic University Loboda Vera vera_loboda@mail.ru Karshi State University Normuradov Muradulla m.normuradov@mail.ru

17 Kuchabog St., Karshi, 180103, Uzbekistan

Karshi Engineering-Economics Institute Donaev Burkhon donaev.sardor@gmail.com

225 Mustakillik Sqr., Karshi, 180100, Uzbekistan

Tashkent State Technical University Turapov Ilkhom turapov_19_86@mail.ru

2 Universitetskaya St., Tashkent, 100095, Uzbekistan

Formation of Mn4 Si7 films by magnetron sputtering and a wide range of their thermoelectric properties In the paper, films of higher manganese silicide Mn4Si7 have been made and a lot of their properties have been investigated. The composition and structure of the films formed by ion-plasma magnetron sputtering were examined by scanning electron microscopy and X-ray analysis. The temperature dependences of film resistivity (by the four-probe method), of their Seebeck coefficient (by the two-probe method), as well as their Hall constant and optical reflectivity spectra (at room temperature). Their thermoelectric figure of merit, the energy-gap width (0.66 eV), charged-particle density and mobility, etc., were calculated. The properties of the films in the amorphous and polycrystalline phases were compared. The thermopower of the Mn4Si7 film was established to increase by about 6 times during the transition from the amorphous phase to the polycrystalline one. The results obtained indicate that it is possible to use this film in heat wave detectors. 10.18721/JPM.16207 621.52 magnetron sputtering cleaning of silicon wafer resistivity silicon thermoelectric properties https://physmath.spbstu.ru/article/2023.66.7/ 07_78-88_16(2)2023.pdf

RAR RUS 89-97 Tashkent State Technical University Named after Islam Karimov Shirinov Ganjimurod ganjimurod777@gmail.com

2, Universitetskaya St., Tashkent,100095, Uzbekistan

Tashkent State Technical University Named after Islam Karimov Donaev Sardor sardor.donaev@gmail.com

2, Universitetskaya St., Tashkent,100095, Uzbekistan

0000-0002-9815-2111 Tashkent State Technical University Named after Islam Karimov Umirzakov Baltokhodja be.umirzakov@gmail.com

2, Universitetskaya St., Tashkent,100095, Uzbekistan

Peter the Great St. Petersburg Polytechnic University Loboda Vera vera_loboda@mail.ru Emission, optical and electrical properties of GaInP/GaP nanofilms In order to search for materials with improved semiconductor properties, thin films of GaInP have been fabricated on the GaP surface (the molecular beam epitaxy and ion implantation procedures were used). These films were investigated by the Auger electron spectroscopy, ultraviolet photoelectron and light absorption ones. The energy and angle dependences of the secondary-electron-emission coefficient (SEEC) were obtained as well. An analysis of the experimental data allowed for the first time to determine the main energy-band and emission parameters of the Ga0.6In0.4P/GaP(111) nanofilm. The energy-gap width was found to be 1.85 eV, which was significantly less than that of the substrate GaP, and thus, the maximum value σmax of the SEEC and the quantum yield K of photoelectrons (at hν = 10.8 eV) values of the Ga0.6In0.4P/GaP system decreased slightly relative to the pure GaP. 10.18721/JPM.16208 621.52 band gap photoabsorption energy-band parameter nanofilm heterostructure https://physmath.spbstu.ru/article/2023.66.8/ 08_89-97_16(2)2023.pdf

RAR RUS 98-110 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

Al-Baath University Kafa Noha nohakafa10@gmail.com

Al-Baath University, Damascus ‒ Aleppo Highway, Homs‎, PP75+5VC, Syrian Arab Republic

Determination of conditions for obtaining radioactivity of nitrogen-13 isotope for medical use by NX2 dense plasma focus device In the paper, a theoretical study to calculate the value of the radioactivity ‎of nitrogen-13 isotope required for use in positron emission tomography (PET) has been presented. The isotope is produced by deuteron beams from NX2 dense plasma focus ‎device. First the effect of three factors was studied, namely, the deuterium gas density, exposure ‎time and the repetition rate of the device. ‎The results showed an increase in radioactivity as deuterium gas pressure decreased. It was next possible to obtain four radioactivity values, suitable for use in PET, by varying the two rest factors. 10.18721/JPM.16209 533.9.07 ‎nitrogen-13 isotope NX2 dense plasma focus device radioactivity https://physmath.spbstu.ru/article/2023.66.9/ 09_98-110_16(2)2023.pdf

RAR RUS 111-120 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 Peter the Great St. Petersburg Polytechnic University Mitrankov Yuriy mitrankovy@gmail.com

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Machine learning models to determine unobservable centrality-related parameter values for a wide range of nuclear systems at the energy of 200 GeV In the paper, a comparative analysis and a search for the optimal machine learning model have been conducted. The model should predict the values of unobservable centrality-related quantities based on the experimental data for observable quantities, namely, the number of charged particles and the number of neutral ones born in the interactions of both heavy and light ultrarelativistic nuclei. The sought-for unobservable values were the numbers of wounded nucleons involved in the interactions and of the binary nucleon-nucleon collisions. Linear and polynomial regressions of various degrees, a decision tree (DT), a random forest (RF), and a multilayer perceptron (MP) were chosen and considered as machine learning models. The prediction accuracy of the models was characterized and tested by the coefficient of determination. The DT, RF, and MP models were found to predict the desired values with the highest accuracy, i.e., they gave equally good results. 10.18721/JPM.16210 539.12 machine learning nuclei collisions regression decision tree random forest multilayer perceptron https://physmath.spbstu.ru/article/2023.66.10/ 10_111-120_16(2)2023.pdf

RAR RUS 121-131 0000-0002-8910-4775 Peter the Great St. Petersburg Polytechnic University Lobanov Andrey lobanov2.aa@edu.spbstu.ru Peter the Great St. Petersburg Polytechnic University Berdnikov Alexander alexber@phmf.spbstu.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Peter the Great St. Petersburg Polytechnic University Mitrankova Mariia mashalario@gmail.com Machine learning models to find unobservable centrality-related parameter values in collisions of different nuclei in the initial energy range from 40 to 200 GeV This paper continues studies in machine learning models capabilities aimed to finding the best way to predict the values of unobservable quantities that characterize centrality, based on experimental data for observable quantities: the number of charged particles and the number of neutrons produced in ultrarelativistic nuclear interactions. The sought-for unobservable quantities were the number of wounded nucleons involved in the interaction and the number of binary nucleon-nucleon collisions. A decision tree, a random forest, and a multilayer perceptron (MP) were tested as machine learning models. The prediction accuracy of the models was characterized by the coefficient of determination R2. Dependences of R2 values on initial energies (40 – 200 GeV) for different systems of colliding nuclei were obtained. The MP model was found to be able to predict the values of unknown quantities in a wide range of initial energies for different systems of nuclear interactions with good accuracy. 10.18721/JPM.16211 539.12 machine learning nuclei collisions initial energy R-squared multilayer perceptron https://physmath.spbstu.ru/article/2023.66.11/ 11_121-131_16(2)2023.pdf

RAR RUS 132-145 Nantong University, Ocean University of China Akintsov Nikolai akintsov777@mail.ru

People’s Republic of China

Kuban State University Nevecheria Artem artiom1989@mail.ru Kuban State University Martynov Alexander martynov159@yandex.ru The motion of an uncharged relativistic particle: an analysis of its integrable motion integrals dynamics In this study, the dynamics of a relativistic particle that does not have an electric charge and is under the action of an external force has been analyzed on the basis of the special theory of relativity. The accelerated motion of such a particle was also investigated in the absence of an external electromagnetic field specified by the scalar and vector potentials. An analytical method for efficient writing of classical equations of relativistic dynamics was developed, and an estimate of integrals of motion was carried out. The motion integral was established to be valid both for charged particles and uncharged ones. The use of motion integrals made it possible to describe the relationship between dynamic parameters. The dependence of the x space-time coordinate on the integral of motion was also obtained. 10.18721/JPM.16212 530.121 motion integral relativistic particle energy radiative friction radiation intensity https://physmath.spbstu.ru/article/2023.66.12/ 12_132-145_16(2)2023_1.pdf

RAR RUS 146-160 0000-0003-0985-5964 Institute for Analytical Instrumentation of the RAS Berdnikov Alexander asberd@yandex.ru 0000-0003-3514-8577 Peter the Great St. Petersburg Polytechnic University Solovyev Konstantin k-solovyev@mail.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

A numerical algorithm for constructing polynomials deviating least from zero with a given weight The article considers numerical algorithms for determining the coefficients of polynomials with a fixed leading coefficient, the algorithms supplying a minimum deviation from zero in a minimax norm with a given weight function. The polynomials serve as a useful tool in many numerical methods, in particular, in the Lanczos’ tau method which provides an approximate numerical analytic solution of ordinary differential equations with coefficients as polynomials in the independent variable. The well-known Chebyshev polynomials determined analytically are the special case of such polynomials, however, in most cases of weight functions, such polynomials can only be determined and tabulated numerically. 10.18721/JPM.16213 537.213, 537.612, 517.5 minimax norm Chebyshev polynomial optimal approximation interpolation numerical algorithm https://physmath.spbstu.ru/article/2023.66.13/ 13_146-160_16(2)2023.pdf