2304-9782, 2618-8686, 2405-7223 13 4 2020 1-218

RAR RUS 9-27 Ioffe Physical-Technical Institute of the Russian Academy of Sciences Vaganov Sergei SV.Exciton@mail.ioffe.ru Ioffe Physical-Technical Institute of the Russian Academy of Sciences Panfilov Andrei a.panfilov@mail.ioffe.ru Ioffe Physical-Technical Institute of the Russian Academy of Sciences Seisyan Ruben rseis@ffm.ioffe.ru An exciton in the superstrong and hyperstrong magnetic fields The transformation of excitonic states in the raising magnetic field has been investigated beginning with the diamagnetic exciton (strong field) through excitonic magnetopolymer (superstrong field) to the QEL exciton (hyperstrong magnetic field). The effects induced by this transformation was considered. The capability of the exciton as a model object to study the hydrogen and positron atoms in superstrong and hyperstrong magnetic fields was also analysed. 10.18721/JPM.13401 537.6, 538.9, 539.1 diamagnetic exciton excitonic magnetopolymer superstrong magnetic field quantum electromagnetic limit hyperstrong magnetic field https://physmath.spbstu.ru/article/2020.50.1/ 01_9-27_13(4)2020.pdf

RAR RUS 28-38 0000-0002-4113-0405 Peter the Great St. Petersburg Polytechnic University Vanina Polina p.yu.vanina@gmail.com Peter the Great St. Petersburg Polytechnic University Silin Nikita silin.ns@edu.spbstu.ru Bosak Alexei Peter the Great St. Petersburg Polytechnic University Chernyshov Dmitry chernyshov65@gmail.com Ioffe Physical Technical Institute of the Russian Academy of Sciences Naberezhnov Alexander alex.nabereznov@mail.ioffe.ru Temperature evolution of diffuse scattering in the strontium-barium niobate SBN-60 single crystal in the relaxor state Temperature dependences of synchrotron radiation diffuse scattering on the model relaxor single crystal Sr0.6Ba0.4Nb2O6 (SBN-60) have been studied in the temperature interval from 90 to 290 K in the vicinities of lattice points (332), (412) and (002) in the [001], [010] and [1 0] directions. This diffuse scattering (DS) has been shown to be a strongly anisotropic with intensity IDS(T, q) proportional q–α where q is a reduce wavevector. The temperature dependences of the parameters α have been obtained, and it is established, that the microscopic modification of structure in the SBN-60 continues on cooling below the temperature of transition to the relaxor state. 10.18721/JPM.13402 538.911, 539.26 diffuse scattering synchrotron radiation relaxor strontium-barium niobate crystal structure https://physmath.spbstu.ru/article/2020.50.2/ 02_28-38_13(4)2020.pdf

RAR RUS 39-46 Herzen State Pedagogical University of Russia Gorokhovatskiy Yuriy yurig@fromru.com Herzen State Pedagogical University of Russia Temnov Dmitry tde@herzen.spb.ru Herzen State Pedagogical University of Russia Sotova Yulia juliasotova1992@mail.ru Rheological parameters’ effect on the electret properties of polyvinylidene fluoride It is known that polymer films based on a copolymer of polyvinylidene fluoride and tetrafluoroethylene P(VDF-TFE) have piezoelectric properties, and these properties appear only after preliminary stretching of the films. The polar crystalline β-phase of the copolymer is responsible for the piezoelectric properties in the P(VDF-TFE), the percentage of this phase in the polymer can vary. In this work, we have studied the influence of the orientational stretching rate on the stability of the electret, and, as a consequence, the piezoelectric state. The influence of rheological parameters on the polymer structure and the parameters of electrically active defects responsible for polarization processes is shown. 10.18721/JPM.13403 538.9 electret state polyvinylidene fluoride tetrafluoroethylene piezoelectric effect thermostimulated spectroscopy https://physmath.spbstu.ru/article/2020.50.3/ 03_39-46_13(4)2020.pdf

RAR RUS 47-60 Peter the Great St. Petersburg Polytechnic University Bulovich Sergei bulovic@yandex.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

An implicit economical algorithm for numerical integration of the equation system describing a multiphase flow state with common pressure An economical scheme for numerical integrating the system of differential equations has been proposed for the model of a multiphase medium with a common pressure (in the barotropic approximation) in liquids. The algorithm allows us to consider an arbitrary number of liquids and admits the possibility of degeneration of this parameter to one liquid in the calculation process. The equations of states for liquids have no restriction related to the finite compressibility of the medium, i.e. the liquid can be incompressible. An implicit method for generating a solution is used. The efficiency is ensured by the fact that the algorithm for constructing the inverse matrix is based on the splitting scheme for physical processes and the solvability of equations within scalar runs. As an example, the flow variant for three liquids is considered. 10.18721/JPM.13404 519.63:621.039 multi-fluid model barotropic approximation implicit algorithm numerical simulation Cauchy problem https://physmath.spbstu.ru/article/2020.50.4/ 04_47-60_13(4)2020.pdf

RAR RUS 61-76 Ioffe Physical-Technical Institute of the Russian Academy of Sciences Kovalenko Anatoliy ras-kan@mail.ru NRC «Kurchatov Institute» – PNPI Koptyuhov Artem t44h@yandex.ru

Gatchina of Leningrad region, Russian Federation

Peter the Great St. Petersburg Polytechnic University Meshcheryakov Dmitry fess_i@bk.ru JSC “Atomproekt”; Schuklinov Alexey mupol@mail.ru Thermokinetic processes in the corium traps of high-temperature melt during the reactor accidents at an a-plant: simulation The two-stage model of changing the thermal and phase state of the active zone melt in the cooled subreactor crucible trap when interacting with the sacrificial material and when crystallizing the diluted corium after the gravitational inversion of its oxide and metal components is presented. The simulation is based on the generalized formulation of Stefan's task. The results of the end-to-end calculation of the COMSOL Multiphysics package show that the thermokinetic processes examined generally reduce the temperature and density of the corium, reduce heat flows on the trap body, minimize the release of hydrogen and radioactive fission products with their retention in a controlled thermal and phase state until full crystallization. 10.18721/JPM.13405 53.072; 53:004 melt active zone subreactor crucible trap sacrificial material thermal state https://physmath.spbstu.ru/article/2020.50.5/ 05_61-76_13(4)2020.pdf

RAR RUS 77-88 Peter the Great St. Petersburg Polytechnic University Khrapunov Evgenii hrapunov.evgenii@yandex.ru

195251, St. Petersburg, Polytechnicheskaya St, 29

Peter the Great St. Petersburg Polytechnic University Chumakov Yuri chymakov@yahoo.com Influence of the slope angle of a locally heated surface on the heat transfer during bifurcation of a pure thermal plume The results of numerical simulation of the puffing regime of a pure thermal plume, which forms above a slightly inclined (with respect to the horizon) surface have been presented. The flow structure in the near-wall region was investigated and the fields of the velocity components were analyzed. Particular attention was paid to the analysis of the distribution of instantaneous, time- and surface-averaged values of the heat transfer coefficient α. Based on the presented results, it was concluded that there was an optimal angle of inclination of the surface maintaining the most efficient heat transfer with a developed periodic flow regime. 10.18721/JPM.13406 532.5:536.24 natural convection numerical simulation bifurcation heat transfer puffing https://physmath.spbstu.ru/article/2020.50.6/ 06_77-88_13(4)2020.pdf

RAR RUS 89-101 Scientific Research Institute for Optoelectronic Instrument Engineering Kotmakova Anna www.anechka_kotmakova@mail.ru Peter the Great St. Petersburg Polytechnic University Gataulin Yakov yakov_gataulin@mail.ru Peter the Great St. Petersburg Polytechnic University Yuhnev Andrey a.yukhnev@mail.ru Peter the Great St. Petersburg Polytechnic University Zaytsev Dmitry zaitsev-aero@yandex.ru The abdominal aorta bifurcation with iliac arteries: the wall elasticity effect on the flow structure For the first time, a numerical study of the effect of vascular elasticity on blood flow has been carried out using a model of the abdominal aorta bifurcation with iliac arteries of the average statistical geometry. The greatest effect of elasticity was shown to be observed in the abdominal aorta before bifurcation where an initial oval cross-section shaping into a circle. Taking into account the elasticity of the walls, the flow structure remained unchanged, but the maximum flow rate increased by 40 % in the abdominal aorta. In the abdominal-aortic bifurcation region the cycle-averaged shear stresses decreased by 20%, and their oscillation index increased by 60%. 10.18721/JPM.13407 532.5+612.13 abdominal aorta’s bifurcation numerical simulation wall elasticity blood flow structure https://physmath.spbstu.ru/article/2020.50.7/ 07_89-101_13(4)2020.pdf

RAR RUS 102-109 0000-0003-3514-8577 Peter the Great St. Petersburg Polytechnic University Solovyev Konstantin k-solovyev@mail.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Ideal focusing systems with homogenous magnetic fields Cases of charged particle pack ideal focusing in the presence of constant magnetic field have been considered. One-directional ideal space-time focusing was shown to remain only on conditions that a magnetic field being homogenous and its direction being the same as the one of quadratic potential growth. Axially symmetric electrostatic fields with superimposed magnetic field were taken as an example because of their practical importance in the mass spectrometry. It was concluded that at least one equation with separated motion should be linear to maintain the ideal space-time focusing. 10.18721/JPM.13408 537.534.3:621.384.8 (075.8) spectrometry ideal focusing ion trap homogenous magnetic field https://physmath.spbstu.ru/article/2020.50.8/ 08_102-109_13(4)2020.pdf

RAR RUS 110-118 Alferov University Reshetov Ilya reshetov_iv@spbstu.ru Peter the Great St. Petersburg Polytechnic University Alferov University Kaasik Vladimir vkaasik@yandex.ru Alferov University Lipovskii Andrey lipovskii@mail.ru Peter the Great St. Petersburg Polytechnic University Tagantsev Dmitry tagan@dt1386.spb.edu Peter the Great St. Petersburg Polytechnic University Zhurikhina Valentina zhurikhina@mail.edu.ioffe.ru Thermal relaxation of optical nonlinearity in the poled glasses The thermal relaxation of second-order optical nonlinearity in the subsurface layer of a poled soda-lime silicate glass has been studied. The glass annealing below glass transition temperature was shown to lead to full relaxation of the nonlinearity. At the same time, the measurements of thermostimulated depolarization current demonstrated that spatial electric charge formed in the course of the glass polarization relaxed above the glass transition temperature. This allowed concluding that the second-order optical nonlinearity in the poled glasses was not induced by the spatial electric charge. 10.18721/JPM.13409 53.097 glass optical nonlinearity polarization poling relaxation depolarization thermostimulated depolarization current https://physmath.spbstu.ru/article/2020.50.9/ 09_110-118_13(4)2020.pdf

RAR RUS 119-132 Kozhevnikov Vadim vadim.kozhevnikov@gmail.com 7006335646 Peter the Great St. Petersburg Polytechnic University Privalov Vadim kafedra@physics.spbstu.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

AAD-9657-2019 57197390995 Peter the Great St. Petersburg Polytechnic University Fotiadi Alexander fotiadi@rphf.spbstu.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Effective mode volume and estimation of helium-neon laser output power The relationship between the generated power and the mode volume of the fundamental mode of a plane-sphere resonator is considered in the article exemplified a He-Ne laser. A novel technique based on the volume of the generating mode has been proposed to estimate the output radiation power of a gas-discharge laser with an arbitrary cross-sectional shape of an active element. It was shown that the results of calculations of the generated power, carried out on the basis of the effective mode volume, which took into account the transverse distribution of the population inversion of the active medium, were in better agreement with the experimental data and the results of estimates using other methods. 10.18721/JPM.13410 621.373.8 mode volume effective mode volume population inversion He-Ne laser power https://physmath.spbstu.ru/article/2020.50.10/ 10_119-132_13(4)2020.pdf

RAR RUS 133-148 Peter the Great St. Petersburg Polytechnic University Karov Dmitry dmkarov@yandex.ru Euroacademy Puro Alfred alfredpuro@gmail.com Curved-ray tensor tomography for residual stress measurements in the axisymmetric graded rods For the first time, an algorithm for reconstructing an arbitrary distribution of residual stresses by the polarization tomography method for cylindrical rod structures with a radial distribution of the refractive index has been presented. The reconstruction took into account the ray refraction. The algorithm is based on the expansion of the tensor stress field in angular harmonics (singular value expansion). The case of an axisymmetric tensor field with an arbitrary stress gradient along the cylinder axis was considered. Numerical calculations were carried out for an axially symmetric stress distribution in a gradan for the case of a plane deformation state. The reconstruction was based on the expansion of the stress tensor in eigenfunctions of the boundary value problem. The regularized solution of the resolving equation (of Abelian type) used the expansion in Zernike polynomials. The results of the reconstruction are given with taking into account the additional term due to the deflection of the transmission rays as well as without this doing. 10.18721/JPM.13411 536.421 residual stress integrated photoelasticity transverse translucence GRIN rod lense https://physmath.spbstu.ru/article/2020.50.11/ 11_133-148_13(4)2020.pdf

RAR RUS 149-161 Peter the Great St. Petersburg Polytechnic University Pashkevich Dmitrii pashkevich-ds@yandex.ru

St. Petersburg, Russian Federation

Peter the Great St. Petersburg Polytechnic University Zimin Arseniy fz1min@yandex.ru «New Chemical Products» Ltd. Alexeev Yury alexeev-588@yandex.ru

St. Petersburg, Russian Federation

FSUE RSC "Applied Chemistry" Mukhortov Dmitrii

St. Petersburg, Russian Federation

Russian Scientific Center "Applied Chemistry" Kambur Pavel pavel.kambur@mail.ru FSUE RSC "Applied Chemistry" Petrov Valentin valentinpetrov46@mail.ru

St. Petersburg, Russian Federation

JSC "Siberian Chemical Plant" Bazhenov Dmitrii dmitriy_bazhenov@mail.ru JSC "Siberian Chemical Plant" Smolkin Pavel spa-net@mail.ru Peter the Great St. Petersburg Polytechnic University Kapustin Valentin Valentin.Kapustin.2014@yandex.ru

St. Petersburg, Russian Federation

Hydrogen fluoride obtaining from uranium hexafluoride in the combustion mode Currently, there are no effective industrial technologies to return fluorine into a technological cycle. The authors have proposed a method for processing uranium hexafluoride depleted in the U-235 (DUHF) isotope in a hydrogen-oxygen flame that can be used as a basis for obtaining hydrogen fluoride and uranium oxides. Using own devising program code and complex ASTRA.4, performed thermodynamic calculations in the U-F-H-O elements system and it was shown that if the number of hydrogen atoms exceeds the number of fluorine atoms, then at temperatures above 1150 K, the only fluorine-containing substance in the thermodynamically equilibrium mixture was HF, while the main uranium-containing was UO2. The proposed method was experimentally investigated at a pilot plant and it showed that the composition of its products was close to thermodynamic equilibrium. The results can become the basis for industrial technology of the hydrogen fluoride production from DUHF. 10.18721/JPM.13412 544.3:544.45:661.487:621.039.1 depleted uranium hexafluoride uranium dioxide hydrogen fluoride combustion https://physmath.spbstu.ru/article/2020.50.12/ 12_149-161_13(4)2020.pdf

RAR RUS 162-175 Peter the Great St. Petersburg Polytechnic University Pashkevich Dmitrii pashkevich-ds@yandex.ru

St. Petersburg, Russian Federation

FSUE RSC "Applied Chemistry" Mukhortov Dmitrii

St. Petersburg, Russian Federation

Peter the Great St. Petersburg Polytechnic University Kapustin Valentin Valentin.Kapustin.2014@yandex.ru

St. Petersburg, Russian Federation

Russian Scientific Center "Applied Chemistry" Kambur Pavel pavel.kambur@mail.ru Russian Scientific Center "Applied Chemistry" Kurapova Ekaterina e_kurapova@mail.ru Peter the Great St. Petersburg Polytechnic University Zimin Arseniy fz1min@yandex.ru Peter the Great St. Petersburg Polytechnic University Maslova Anastasia anastasiiamaslova5@gmail.com The stability of flame front and the composition of combustion products of ammonia in oxygen in the presence of hydrogen fluoride The authors have proposed a way for producing hydrogen fluoride (the major fluorinating agent in the modern industry) from ammonium bifluoride (by-product in the production of extraction phosphoric acid, tantalum, niobium, etc.) by burning up NH4F∙HF in oxygen. Calculations performed via program complex ASTRA.4 showed that the only fluorine-containing substance was hydrogen fluoride, whereas nitric fluorides and oxyfluorides being absent under the ratio of chemical elements N-1.0; H-5.0; F-2.0; O-1.5 (according to the proposed process), in the temperature range 600 – 2500 K, in thermodynamically equilibrium mixture. The combustion of ammonia in oxygen in the presence of hydrogen fluoride was experimentally investigated and it was found the feasibility of forming a stable flame, where a molar ratio of ammonia/hydrogen fluoride consumptions was 1: 2, only by using methane as a fuel. The conditions for the ratio of component consumptions were determined. 10.18721/JPM.13413 544.3:544.45:536.7:661.487:536.464 ammonium bifluoride ammonia hydrogen fluoride combustion tunnel burner reactor https://physmath.spbstu.ru/article/2020.50.13/ 13_162-175_13(4)2020.pdf

RAR RUS 176-184 Peter the Great St. Petersburg Polytechnic University Babich Ekaterina babich.katherina@gmail.com University of Eastern Finland Reduto Igor igor.reduto@uef.fi

Finland

Institute for Problems of Mechanical Engineering RAS Alexey V. red-alex@mail.ru Alferov University Reshetov Ilya reshetov_iv@spbstu.ru Peter the Great St. Petersburg Polytechnic University Zhurikhina Valentina zhurikhina@mail.edu.ioffe.ru Alferov University Lipovskii Andrey lipovskii@mail.ru Modification of glass surface by a high electric field The work has studied an effect of a high DC field on the composition and properties of the subsurface region of a multicomponent silicate glass. The concentration of alkali ions in the subsurface glass region was shown to drastically decrease under the high electric field. This led to a change in the ion-exchange characteristics of glasses and their resistance to etching. The effect allows employing the poled regions of the glass surface as dielectric masks in the formation of gradient optical structures, as well as relief microstructures, e.g., channels for microfluidics, in glass substrates. The advantage of this approach is that there is no need in multiple lithography using liquid chemicals. This reduces the cost and makes this technological process environment friendly. 10.18721/JPM.13414 538.958 high electric field chemical etching ion etching ion exchange https://physmath.spbstu.ru/article/2020.50.14/ 14_176-184_13(4)2020.pdf

RAR RUS 185-202 0000-0001-5988-1429 Peter the Great St. Petersburg Polytechnic University Liokumovich Leonid leonid@spbstu.ru Concern CSRI “Elektropribor” Kostromitin Aleksey kostromitin.aleksei@yandex.ru Skliarov Philip 0000-0001-8448-2024 Peter the Great St. Petersburg Polytechnic University Kotov Oleg kotov@rphf.spbstu.ru An output power level of the fiber-optic interferometric schemes with fiber Bragg gratings for multiplexing the sensitive elements The paper continues a series of articles devoted to the procedure proposed by the authors how to calculate the required elements’ parameters and the output optical power level of the fiber-optic interferometric schemes with time-division multiplexing (TDM) of sensing elements. In particular, the schemes based on fiber Bragg gratings have been analyzed. The proposed method enables to ensure uniformity of powers of optical signals from individual sensing elements, as well as to evaluate how the deviations of elements’ parameters from the nominal ones influence the optical powers. According to the calculation methodology, a sequence of applying the required expressions was substantiated and some obtained results and an analysis of characteristic behaviors for the considered optical fiber circuits were exemplified. The proposed approach was recommended for design of interferometric optical fiber sensors with multiplexed sensing elements. 10.18721/JPM.13415 535.3, 535-15, 535.417 fiber-optic interferometric sensor Bragg grating optical power time-division multiplexing https://physmath.spbstu.ru/article/2020.50.15/ 15_185-202_13(4)2020.pdf

REV RUS 203-215 University of South Bohemia in České Budejovice Valdman Jan jan.valdman@gmail.com

Česká Republika

0000-0002-1022-0221 Peter the Great St. Petersburg Polytechnic University Frolov Maxim frolov_me@spbstu.ru

St. Petersburg, Russian Federation

Functional-type a posteriori error estimates for solutions of problems in deformable solid mechanics The paper provides a historical review and recent developments on theoretical justification and numerical implementations of functional a posteriori error estimates and adaptive algorithms for approximate solutions to problems in deformable solid mechanics. The efficient practical implementation of such methods is a relevant objective, including for modern engineering practice. 10.18721/JPM.13416 519.63: 539.3 error estimates finite element method adaptive algorithms solid mechanics https://physmath.spbstu.ru/article/2020.50.16/ 16_203-215_13(4)2020.pdf