<?xml version="1.0" encoding="utf-8"?>
<journal>
  <titleid/>
  <issn>2304-9782, 2618-8686, 2405-7223</issn>
  <journalInfo lang="ENG">
    <title>St. Petersburg Polytechnic University Journal: Physics and Mathematics</title>
  </journalInfo>
  <issue>
    <volume>17</volume>
    <number>4</number>
    <altNumber> </altNumber>
    <dateUni>2024</dateUni>
    <pages>1-177</pages>
    <articles>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>9-19</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0009-0000-1236-0319</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Lobachevsky State University of Nizhni Novgorod</orgName>
              <surname>Chizhova </surname>
              <initials>Anastasia</initials>
            </individInfo>
          </author>
          <author num="002">
            <individInfo lang="ENG">
              <orgName>Lobachevsky State University of Nizhni Novgorod</orgName>
              <surname>Nikolskaya</surname>
              <initials>Alena</initials>
              <email>nikolskaya@nifti.unn.ru</email>
              <address>Nizhni Novgorod, Russian Federation</address>
            </individInfo>
          </author>
          <author num="003">
            <authorCodes>
              <orcid>0009-0009-4269-4585</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Lobachevsky State University of Nizhni Novgorod</orgName>
              <surname>Zaitseva</surname>
              <initials>Ekaterina</initials>
            </individInfo>
          </author>
          <author num="004">
            <authorCodes>
              <orcid>0000-0001-8850-2651</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>National Research Lobachevsky State University of Nizhni Novgorod</orgName>
              <surname>Konakov</surname>
              <initials>Anton</initials>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">The electronic band structure of hexagonal silicon polytypes</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">This work is devoted to calculations and an analysis of the electronic band structure (BS) for hexagonal (2H, 4H, 6H) and rhombohedral (9R, 15R, 21R) silicon polytypes using the empirical pseudopotential method (EPM). The calculation results for 3C, 2H and 4H have been in good agreement with experimental data. The data for 6H, 15R and 21R were obtained and analyzed for the first time. The BS for the 9R polytype calculated by EPM was almost identical to that obtained by the density functional theory method. This result indicates the possibility of using EPM for constructing BSs of various polytypes. The advantages of EPM over others were noted. The dependences of the widths of the direct and indirect energy gaps on the of crystal hexagonality degree were also studied. A partial “straightening” of the BS was established with increasing this degree of the objects.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17401</doi>
          <udk>538.915</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>silicon</keyword>
            <keyword>band structure</keyword>
            <keyword>pseudopotential method</keyword>
            <keyword>polytype</keyword>
            <keyword>hexagonality</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.1/</furl>
          <file>01_9-19_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>20-33</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Koyokin </surname>
              <initials>Vadim </initials>
              <email>koiokin@mail.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Bulovich</surname>
              <initials>Sergei</initials>
              <email>bulovic@yandex.ru</email>
              <address>Russia, 195251, St.Petersburg, Polytechnicheskaya, 29</address>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">2D-statement simulation of thermogasdynamic processes in a rotary-blade engine with external heat supply</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">To analyze the characteristics of a rotor-blade engine with external heat supply, a 2D model of this mechanism is considered. The simulation took into account the movement of the working chambers of the engine and the change in their shape. When the chamber came into contact with the gas distribution windows, either gas was transferred to the heat exchangers or the chamber was filled with gas. The formation and development of the jet flow structure in the mass transfer process of an engine – heat exchanger is investigated. The heat transfer process in the engine heat exchangers was modeled using the volumetric heat transfer coefficient, and their hydraulic resistance was also taken into account. The results of the study of heat and mass transfer processes in the engine were presented in the form of cyclograms and indicator diagrams. A comparison was made with the results obtained using the nodal value method.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17402</doi>
          <udk>621.412</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>rotary-blade engine with external heat supply</keyword>
            <keyword>simulation</keyword>
            <keyword>numerical integration УДК:	621.412</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.2/</furl>
          <file>02_20-33_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>34-47</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Ris</surname>
              <initials>Vladimir</initials>
              <email>vvris@spbstu.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Galaev </surname>
              <initials>Sergey</initials>
              <email>galaev@spbstu.ru</email>
            </individInfo>
          </author>
          <author num="003">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Aleksander</surname>
              <initials>Levchenya</initials>
              <email>levchenya@yandex.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">A spatially periodic flow and heat transfer in a rectangular channel with one ribbed wall</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">The systematic data on the effect of ribbing on the parameters of a relative (in comparison with a smooth channel) increase in hydraulic resistance εp and heat transfer εq in the range of Reynolds numbers from 50 to 8∙106 has been obtained by numerical modeling of a developed spatially periodic flow and stabilized heat transfer of incompressible gas with a Prandtl number of 0.7 in a rectangular channel with one-sided internal ribbing. In the laminar regime, the εq value was found to be small and amounted about 10%, and εp value exceeding 2.5. In the turbulent regime, the εq value behaved nonmonotonic depending on the Reynolds number, the range of its variation was 1.5–2.6, while εp increased from 3.5 to 7.0.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17403</doi>
          <udk>532.542.4</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>ribbed channel</keyword>
            <keyword>periodic flow</keyword>
            <keyword>heat transfer enhancement</keyword>
            <keyword>RANS model</keyword>
            <keyword>LES-WALE model</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.3/</furl>
          <file>03_34-47_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>48-56</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0000-0003-2327-068X</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Mechanical Engineering Research Institute of the RAS</orgName>
              <surname>Alifov</surname>
              <initials>Alishir</initials>
              <email>a.alifov@yandex.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Parametric and self-excited oscillations under nonlinear parametric action and lag in elasticity</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">The interaction of parametric oscillations and self-oscillations under nonlinear parametric excitation and delay in elasticity is considered. To solve the differential equations of the system motion, the direct linearization method was used and equations for non-stationary and stationary modes of oscillations were derived. Using the Routh–Hurwitz criteria, stability conditions for stationary regimes were obtained. To find out the effect of nonlinear parametric excitation on the dynamics of mixed autoparametric oscillations, relevant calculations were carried out and a comparison was made of the results obtained in the presence and absence of delay. According to calculated data, in the presence of a delay, a change in amplitude values occurs, accompanied by a shift in the amplitude curves in the amplitude-frequency area, as well as their narrowing or broadening, compared to no lag. The presence of lag also affects the stability of oscillations.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17404</doi>
          <udk>534.16</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>self-oscillations</keyword>
            <keyword>parametric oscillations</keyword>
            <keyword>interaction</keyword>
            <keyword>nonlinearity</keyword>
            <keyword>delay</keyword>
            <keyword>elasticity</keyword>
            <keyword>method of direct linearization</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.4/</furl>
          <file>04_48-56_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>57-67</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Azerbaijan State Oil and Industry University</orgName>
              <surname>Gamzaev </surname>
              <initials>Khanlar</initials>
              <email>xan.h@rambler.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Identification of the boundary regime in the process of water- oil displacement from the reservoir</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">The water-oil displacement process (from a rectangular reservoir) has been considered, that is described by a nonlinear system of partial differential equations with respect to the reservoir pressure (RP) and displacing phase saturation (DPS). Within the framework of the proposed model, the task of identifying the regime at the output boundary of the reservoir according to the specified conditions at the input boundary was set. The difference approximation method was used to construct a difference analogue of the problem, implicit with respect to RP and explicit with respect to DPS. As a result, an explicit formula was obtained for determining the approximate RP value at the outlet boundary of the reservoir at a given time layer. Taking into account the calculated RP distribution in the reservoir, the DPS distribution in the time layer was determined using an explicit formula. Based on the proposed computational algorithm, numerical experiments were carried out for the model oil reservoir.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17405</doi>
          <udk>532.546: 519.63</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>flooding method</keyword>
            <keyword>two-phase flow</keyword>
            <keyword>displacing phase saturation</keyword>
            <keyword>boundary inverse problem</keyword>
            <keyword>decomposition</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.5/</furl>
          <file>05_57-67_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>REV</artType>
        <langPubl>RUS</langPubl>
        <pages>68-87</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0000-0002-4363-9352</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Korablev</surname>
              <initials>Vadim</initials>
              <email> korablev@spbstu.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0003-0723-622X</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Rozhansky </surname>
              <initials>Vladimir</initials>
            </individInfo>
          </author>
          <author num="003">
            <authorCodes>
              <orcid>0000-0002-8165-0122</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Sarygulov </surname>
              <initials>Askar </initials>
              <email>dept.cfr@unecon.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Physical and technical problems of fusion energy development: From fundamental research to the stage of industrial opening up</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">This review article analyzes the physical and technical problems and judges the prospects for the development of fusion energy, taking into account both the results obtained by an international consortium of scientists within the framework of such projects as ITER and within the framework of individual national programs. Energy supply is one of the most complex challenges that mankind faces in the 21st century. In modern times, about 75 % of humanity's needs are provided by fossil energy carriers: oil, gas and coal. It is obvious now that renewable energy sources have their limit of use, primarily due to the instability of their energy production and the lack of technologies to create reserves in large volumes of energy produced by them. All this forces us to pay attention to such a source as the energy of controlled thermonuclear fusion. The article also analyzes new trends in the development of fusion energy based on consortia of scientists and the private sector, which set themselves the tasks of its accelerated commercialization and industrial opening up.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17406</doi>
          <udk>621.039</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>controlled thermonuclear fusion</keyword>
            <keyword>fundamental research</keyword>
            <keyword>industrial development</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.6/</furl>
          <file>06_68-87_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>88-97</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0000-0002-3640-677X</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Ioffe Institute</orgName>
              <surname>Kaveev</surname>
              <initials>Andrey</initials>
              <email>kaveev@mail.ioffe.ru</email>
              <address>St. Petersburg, Russian Federation</address>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0001-5547-9387</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Alferov University</orgName>
              <surname>Fedorov</surname>
              <initials>Vladimir</initials>
              <email>fedorov_vv@spbstu.ru</email>
            </individInfo>
          </author>
          <author num="003">
            <authorCodes>
              <orcid>0009-0006-3064-4175</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Alferov University </orgName>
              <surname>Miniv </surname>
              <initials>Dmitriy </initials>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Formation of diluted nitride InAs1–хNх core-shell nanowires on silicon</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">Epitaxial arrays of the InAs1–хNх core-shell nanowires have been synthesized on Si (111) for the first time. The growth of the nanowires with a wurtzite-type crystal structure was demonstrated by a self-induced mechanism using the molecular beam epitaxy with plasma-assisted nitrogen activation. Using the transmission electron microscopy and X-ray diffraction analysis, a volume decrease in the wurtzite crystal unit cell with increasing nitrogen content was revealed.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17407</doi>
          <udk>539.231, 539.261</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>InAs1–хNх</keyword>
            <keyword>nanowire</keyword>
            <keyword>X-ray diffraction analysis</keyword>
            <keyword>self-induced growth mechanism</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.7/</furl>
          <file>07_88-97_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>98-105</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Vakulenko </surname>
              <initials>Aleksandr </initials>
              <email>sasha705@mail.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0002-4113-0405</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Vanina</surname>
              <initials>Polina</initials>
              <email>p.yu.vanina@gmail.com</email>
            </individInfo>
          </author>
          <author num="003">
            <authorCodes>
              <orcid>0000-0002-2793-5717</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Filimonov</surname>
              <initials>Alexey</initials>
              <email>filimonov@rphf.spbstu.ru</email>
              <address>St. Petersburg, Russian Federation</address>
            </individInfo>
          </author>
          <author num="004">
            <authorCodes>
              <orcid>0000-0003-4867-1404</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Ioffe Institute of the Russian Academy of Sciences</orgName>
              <surname>Vakhrushev</surname>
              <initials>Sergey</initials>
              <email>s.vakhrushev@mail.ioffe.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Modernization of the methodology for obtaining phase transition temperatures using the piezoresponse force microscopy exemplified by study of a phase transition in the PZT single crystal</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">A chopper amplification technique has been developed to correct zero drift when measuring the magnitude of the piezoelectric response using the PFM method under conditions of continuous temperature change. Employing this technique, the temperatures of the antiferroelectric – ferroelectric phase transition of a PZT 4% single crystal were obtained. A qualitative agreement with the results of measuring the saturation polarization obtained by the Sawyer – Tower method makes it possible to assert that the technical assumptions made are quite reasonable and the developed method is worthy of widespread use in such measurements.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17408</doi>
          <udk>538.956</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>ferroelectric</keyword>
            <keyword>lead zirconate titanate</keyword>
            <keyword>piezoresponse</keyword>
            <keyword>atomic force microscopy</keyword>
            <keyword>phase transition</keyword>
            <keyword>Sawyer – Tower method</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.8/</furl>
          <file>08_98-105_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>106-113</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Indira Mahavidyalaya, Kalamb Dist. Yavatmal</orgName>
              <surname>Nemade</surname>
              <initials>Kailash</initials>
              <email>krnemade@gmail.com</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0002-6896-4610</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, India</orgName>
              <surname>Maheshwary </surname>
              <initials>Prashant </initials>
              <email>prashantmaheshwary51@gmail.com</email>
              <address>MH SH 236, Dist, near Shree Saraswati Temple, Malkapur, Kalamb, Maharashtra 445401, India</address>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Vertical spin valve performance of NiFe/Co-PANI/NiFe system</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">The organic materials are found to be potent candidates for spintronics applications. Here, we have presented a cobalt-loaded polyaniline (Co-PANI)-based spin valve with NiFe alloy as ferromagnetic contacts. The spin valve signal was observed at temperatures from 10 K to 300 K. The IV curve of the spin valve exhibited a linear relationship, which showed that Co-PANI behaved like metal in this valve. The highest value of the magnetoresistance (MR) was found to be 8.13% at 10 K, whereas it decreased to 3.32 % at 300 K. Similarly, the bias current effect showed that the highest value of MR was 3.46 % for 10 A, which reduced down to 0.93% for 40 A.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17409</doi>
          <udk>538.955-405</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>polymeric composites</keyword>
            <keyword>magnetic materials</keyword>
            <keyword>spin-valve</keyword>
            <keyword>organic spintronics</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.9/</furl>
          <file>09_106-113_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>114-120</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Institute for Analytical Instrumentation of the RAS</orgName>
              <surname>Pomozov</surname>
              <initials>Timofey</initials>
              <email>tim-kor@mail.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <individInfo lang="ENG">
              <orgName>Institute for Analytical Instrumentation of the RAS</orgName>
              <surname>Muradymov </surname>
              <initials>Marat </initials>
              <email>m.muradymov@gmail.com</email>
            </individInfo>
          </author>
          <author num="003">
            <authorCodes>
              <orcid>0009-0003-8001-7469</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Institute for Analytical Instrumentation of the RAS</orgName>
              <surname>Tkach</surname>
              <initials>Egor</initials>
              <email>egorka765@gmail.com</email>
            </individInfo>
          </author>
          <author num="004">
            <authorCodes>
              <orcid>0000-0002-0547-987X</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Institute for Analytical Instrumentation RAS</orgName>
              <surname>Yavor</surname>
              <initials>Mikhail</initials>
              <email>mikhail.yavor@gmail.com</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">The efficiency of a focusing system when ion current transporting to the differential pumping system of a mass spectrometer</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">In this work, a charge particle beam transport in a corona discharge ion source with a thin diaphragm focusing system taking into account the gas-dynamic flow in the vicinity of the nozzle has been studied experimentally. The space of influence of the gas-dynamic flow on the ion transport in the vicinity of the nozzle was shown not to exceed two nozzle diameters. 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. Using the focusing system allowed one to triple the current entering the collector and to raise the sum of currents entering the nozzle and collector by an order of magnitude.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17410</doi>
          <udk>621.384.8</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>ion source</keyword>
            <keyword>mass spectrometer</keyword>
            <keyword>differential pumping system</keyword>
            <keyword>focusing system</keyword>
            <keyword>ion transport</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.10/</furl>
          <file>10_114-120_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>121-129</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0000-0003-4292-0959</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Golovitski</surname>
              <initials>Alexander</initials>
              <email>alexandergolovitski@yahoo.com</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">Ionic diffusion into the peripheral area of a glow discharge in the electronegative gases</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">In the paper, the effect of negative ion diffusive penetration from the central space representing the ion-ion plasma on the electron-ion plasma located in the peripheral area of a positive column of a glow discharge in the strong electronegative gases has been studied. The said penetration was shown to be responsible for formation of an electron density profile being close to linear within the peripheral area and also for sufficient reduction of its transverse size. The explicit approximate analytic expressions for parameters of electron density profile were found. The results of a specially conducted computational experiment were compared with those obtained through the approximate solution, and their good agreement was established (the error did not exceed 13%). The research carried out is important for correct quantitative evaluations of ionization rate, electron temperature and a longitudinal field in a positive column of an electronegative glow discharge.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17411</doi>
          <udk>533.9.01</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>negative ions</keyword>
            <keyword>glow discharge plasma</keyword>
            <keyword>plasma stratification</keyword>
            <keyword>ionic diffusion</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.11/</furl>
          <file>11_121-129_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>130-137</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0009-0005-7144-4746</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University </orgName>
              <surname>Muzyaev</surname>
              <initials>Evgeniy</initials>
              <email>muzyaev.ev@edu.spbstu.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0003-0309-5917</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Berdnikov</surname>
              <initials>Yaroslav</initials>
              <email>berdnikov@spbstu.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">The Sivers asymmetry in deep inelastic charged lepton scattering on a transverse polarized proton target</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">In the paper, it has been proposed a calculation algorithm that allows obtaining the value of the Sivers asymmetry in semi-inclusive deep inelastic scattering of charged leptons on a transversely polarized proton using the event generator PYTHIA8 and the StringSpinner plug-in. The calculation was performed in the kinematics of the COMPASS experiment: a muon with an energy of 160 GeV scatters on a stationary proton target. The proposed algorithm was shown to make it possible to estimate high accurately the Sivers asymmetry of the final hadron.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17412</doi>
          <udk>539.12</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>semi-inclusive deep inelastic scattering</keyword>
            <keyword>polarization</keyword>
            <keyword>Sivers asymmetry</keyword>
            <keyword>event generator</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.12/</furl>
          <file>12_130-137_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>138-146</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0009-0006-8542-4401</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Shapaev</surname>
              <initials>Dmitry</initials>
              <email>dima.shapaev@yandex.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0003-0309-5917</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Berdnikov</surname>
              <initials>Yaroslav</initials>
              <email>berdnikov@spbstu.ru</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">The creation of direct photons during interactions of deuterium nuclei at energies of 13.5 GeV and 27.0 GeV</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">In this study, the invariant spectra and nuclear modification factors of direct photons produced in deuteron collisions at energies sqrt{s_{NN}} = 13.5 and 27.0 GeV/nucleon, relevant to the NICA project have been obtained by calculation. In doing this, both nuclear modified parton distribution functions and parton distribution ones found for free nucleons were used. Our analysis indicated that the predicted spectra of direct photons as a function of the transverse momentum, as well as the nuclear modification factors in these interactions were scarcely affected by accounting for the nuclear parton distribution function. It also turned out that the nuclear modification factors for direct photons generated in deuteron collisions at the specified energies depended slightly on the transverse momentum within the range from 1 to 5 GeV, differed from unity, exhibiting values around 0.8.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17413</doi>
          <udk>539.122</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>direct photon</keyword>
            <keyword>nuclear modification factor</keyword>
            <keyword>SPD</keyword>
            <keyword>NICA</keyword>
            <keyword>parton distribution function</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.13/</furl>
          <file>13_138-146_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>147-160</pages>
        <authors>
          <author num="001">
            <authorCodes>
              <orcid>0009-0005-2924-9795</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Frolov</surname>
              <initials>Maxim</initials>
            </individInfo>
          </author>
          <author num="002">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Savikovskii </surname>
              <initials>Artem </initials>
              <email>savikovskij.av@edu.spbstu.ru</email>
            </individInfo>
          </author>
          <author num="003">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Semenov</surname>
              <initials>Artem</initials>
              <email>semenov.artem@googlemail.com</email>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">An energy fracture criterion based on dissipative inequality</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">A new approach to obtaining the energy criterion for the fracture of a thermoelastic body with a growing crack has been put forward. The criterion is based directly on the first and second laws of thermodynamics. An analysis was restricted by brittle quasi-static fracture processes in the weakly nonuniform temperature field (WNUTF). The Griffith conception of surface energy supplemented by the temperature dependence of this energy was used. No thermodynamic fluxes were shown to arise in the WNUTF, except for the rate of a growing crack. This result made it possible to extend the Griffith criterion to the nonisothermal case. The vectorial J-integral representing the energy flux vector at the crack tip was established to be the only fracture parameter for thermoelastic media with cracks. Different energy flux vector representation forms for cases of linear and nonlinear thermoelasticity were considered and discussed.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17414</doi>
          <udk>539.3,539.42</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>brittle fracture</keyword>
            <keyword>thermomechanical loading</keyword>
            <keyword>dissipative inequality</keyword>
            <keyword>energy fracture criterion</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.14/</furl>
          <file>14_147-160_17(4)2024.pdf</file>
        </files>
      </article>
      <article>
        <artType>RAR</artType>
        <langPubl>RUS</langPubl>
        <pages>161-174</pages>
        <authors>
          <author num="001">
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Petukhov </surname>
              <initials>Dmitrii</initials>
              <email>d_a_petukhov@mail.ru</email>
            </individInfo>
          </author>
          <author num="002">
            <authorCodes>
              <orcid>0000-0002-1022-0221</orcid>
            </authorCodes>
            <individInfo lang="ENG">
              <orgName>Peter the Great St. Petersburg Polytechnic University</orgName>
              <surname>Frolov</surname>
              <initials>Maxim</initials>
              <email>frolov_me@spbstu.ru</email>
              <address>St. Petersburg, Russian Federation</address>
            </individInfo>
          </author>
        </authors>
        <artTitles>
          <artTitle lang="ENG">A comparison of adaptive algorithms for solving plane problems in the linear elasticity theory using the zero- and first-order Raviart – Thomas elements</artTitle>
        </artTitles>
        <abstracts>
          <abstract lang="ENG">Functional-type a posteriori error estimates are known for many problems of the elasticity theory. However, as followed from the work of S. I. Repin and A. V. Muzalevsky, the use of classical Finite Element Method (FEM) approximations for their implementation may lead to a growing overestimation of the absolute value of an error. Later, in the work of M. E. Frolov, it was shown that the use of approximations for mixed FEMs avoids a growing overestimation of the absolute error with mesh refinements. Further research in this direction was carried out by M. E. Frolov and M. A. Churilova using the simplest Raviart – Thomas and Arnold – Boffi – Falk approximations. In this paper, a comparative analysis is performed for zero-order and first-order Raviart – Thomas finite elements. It is shown for plane problems of linear elasticity that the use of the first-order Raviart – Thomas approximation significantly reduces an overestimation of the absolute error value.</abstract>
        </abstracts>
        <codes>
          <doi>10.18721/JPM.17415</doi>
          <udk>519.63</udk>
        </codes>
        <keywords>
          <kwdGroup lang="ENG">
            <keyword>finite element method</keyword>
            <keyword>reliable a posteriori error estimates</keyword>
            <keyword>Raviart – Thomas elements</keyword>
          </kwdGroup>
        </keywords>
        <files>
          <furl>https://physmath.spbstu.ru/article/2024.77.15/</furl>
          <file>15_161-174_17(4)2024.pdf</file>
        </files>
      </article>
    </articles>
  </issue>
</journal>
