St. Petersburg Polytechnic University Journal: Physics and Mathematics

RAR RUS 7-20 Samdani Mohammed samdanimohd82@gmail.com Ramadevudu Gokarakonda dr.ramdev@gmail.com Chary M. mnchary_phy@rediffmail.com Shareefuddin Mohammed shareef1775@gmail.com EPR, optical and other physical studies of Cr3+-doped MgO-BaO-B2O3-TeO2 glasses Physical, optical and electron paramagnetic resonance (EPR) studies of 15MgO-15BaO-(59.8 – x)B2O3-(10.0 + x)TeO2-0.2Cr2O3 (x = 0, 10, 20, 30 mole %) glass samples have been reported. EPR spectra exhibited some resonance signals. The first one (g = 4.80) had a large zero field splitting parameter (D) and E/D ≤ 1/3, it was attributed to isolated Cr3+ centers in strongly distorted octahedral sites; the second one (g = 1.98) was assigned to Cr3+ centers at axially distorted octahedral sites. The resonance signal at g = 4.26 was assigned to Fe3+ ions, which were in the glass matrix as unwanted impurities. The resonance signal at g = 1.91 indicated the Cr3+-Cr3+ exchange coupled pairs. In the optical absorption spectra, the two observed broad optical bands with 16025 cm–1 and 23474 cm–1 were assigned to 4A2g(F) → 4T2g(F) and 4A2g(F)→ 4T1g(F) transitions, respectively. The site symmetry of Cr3+ is C4v or C3v. Racah parameters, crystal field (Dq) parameters and energy gap were evaluated from the optical spectra. Various other physical parameters like density, etc., are also reported. Citation: M. Samdani, G. Ramadevudu, M.N. Chary, M. Shareefuddin, EPR, optical and other physical studies of Cr3+-doped MgO-BaO-B2O3-TeO2 glasses, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 7–20. DOI: 10.18721/JPM.10401 10.18721/JPM.10401 538.95 borotellurite glass electron paramagnetic resonance (EPR) optical absorption physical properties https://physmath.spbstu.ru/article/2017.38.1/ 01_7_20_10_4_2017.pdf

RAR RUS 21-33 Panov Dmitrii Peter the Great St. Petersburg Polytechnic University Ris Vladimir vvris@spbstu.ru E-5484-2014 56020596900 Peter the Great St. Petersburg Polytechnic University Smirnov Evgeny aero@phmf.spbstu.ru

Russia, 195251, St.Petersburg, Polytechnicheskaya, 29

Eddy resolving numerical simulation of 3d turbulent flow in a 180-degree bend of strong curvature The paper covers LES-WALE and IDDES data obtained with ANSYS Fluent 16.2 for turbulent flow in a strongly curved U-duct of square section (RCL/Dh = 0.65). Results of comparative computations performed with two approaches for Re = 40000 are in a good agreement. For validation study at a higher Reynolds number, Re = 100000, performed under conditions of the well known tests (Cheah et al, 1996; Iacovides et al, 1998), the IDDES approach is used as a resource-saving one. Parametric computations cover analysis of inlet boundary layer thickness on the flow field. The mean velocity field computed is in a satisfactory agreement with the experimental data, and the calculated pressure losses coincide completely with the measured one. The main cause of remaining discrepancies between the calculated and measured velocity field data lies in impossibility to achieve a full accordance of a computational task setting to the test conditions, namely in the part concerning accordance of inlet conditions. Citation: Panov D.O., Ris V.V, Smirnov E.M. Eddy resolving numerical simulation of a 3D turbulent flow in a 180-degree bend of strong curvature, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 21–33. DOI: 10.18721/JPM.10402 10.18721/JPM.10402 532.542.4 U-duct turbulent flow numerical simulation LES IDDES https://physmath.spbstu.ru/article/2017.38.2/ 02_21_33_10_4_2017.pdf

RAR RUS 34-53 Kandasamy Ramasamy future990@gmail.com Zailani Natasha natashaazailani@yahoo.com Fatiha Fatin fatinurfatiha93@gmail.com Impact of nanoparticle volume fractions in the water-based nanofluids on the squeezed MHD nanofluid’s flow over a porous sensor surface The squeezed MHD flow of water-based metallic nanoparticles over a porous sensor surface in the presence of a heat source has been investigated. The physical significance of the problem is the interaction and the geometry of water-based copper (Cu), alumina (Al2O3) and SWCNTs. The governing partial differential equations of momentum and energy were converted into ODEs for assured groups of the controlling parameters. The numerical and analytical solutions of the ODEs were obtained using the fourth or the fifth order Fehlberg method with shooting technique and OHAM and were analyzed. It was found that there was no appreciable difference between them. It was established that, in squeezing flow phenomena, the effect of nanoparticle volume fraction on the (SWCNTs – water) nanofluid in the presence of magnetic field with thermal radiation energy played a dominant role on heat transfer as compared to the other mixtures in the flow regime. Citation:R. Kandasamy, N.A. Bt. M. Zailani, F.N. Bt. Jaafar, Impact of nanoparticle volume fractions in the water-based nanofluids on the squeezed MHD nanofluid’s flow over a porous sensor surface, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 34–53. DOI: 10.18721/JPM.10403 10.18721/JPM.10403 536.24.08 nanoparticle volume fraction squeezed flow sensor surface SWCNT thermal radiation energy https://physmath.spbstu.ru/article/2017.38.3/ 03_34_53_10_4_2017.pdf

RAR RUS 54-72 Pandey Alok mr.alokpandey1@gmail.com Kumar Manoj mnj_kumar2004@yahoo.com Chemical reaction and thermal radiation effects on a boundary layer flow of nanofluid over a wedge with viscous and Ohmic dissipation In this article, we have analyzed the influence of a chemical reaction and thermal radiation on a magnetohydrodynamic (MHD) flow of (Cu – water) nanofluid past a wedge in the occurrence of viscous and Ohmic dissipation. The nonlinearity numerical approach called the Runge – Kutta – Fehlberg method of the 4th-5th order was used with shooting technique to find the results of velocity, temperature and concentration fields for several points of the parameters taken. The skin friction coefficient, the Nusselt and the Sherwood numbers were examined in details and the results were presented in graphic and tabular forms. An analysis of the obtained results revealed that the concentration boundary layer thickness diminishes with an increase in the values of the chemical reaction parameter and the velocity profiles increase with increasing the magnetic field parameter. Citation: A.K. Pandey, M. Kumar, Chemical reaction and thermal radiation effects on a boundary layer flow of nanofluid over a wedge with viscous and Ohmic dissipation, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 54–72. DOI: 10.18721/JPM.10404 10.18721/JPM.10404 536.24.08 chemical reaction nanofluid Ohmic dissipation thermal radiation viscous dissipation https://physmath.spbstu.ru/article/2017.38.4/ 04_54_72_10_4_2017.pdf

RAR RUS 73-81 Zhitelev Vladimir irakupr64@rambler.ru Zvir Elena ea-zvir@niiar.ru Kuprienko Maxim irakupr64@rambler.ru Strozhuk Andrey strozhuk@yandex.ru Nurullina Gulshan ngulshan@yandex.ru Emission gamma tomography of the test fuel assembly for BOR-60 reactor Сomputerized emission gamma tomography of the test leaky fuel assembly irradiated in the research reactor BOR-60 has been carried out at the Material test department of Joint-Stock Company JSC «SSC RIAR» using gamma spectrometry equipment and installation for 2D-positioning placed in a hot cell. The paper describes the gamma tomography installation, reconstruction algebraic iteration scheme used for data processing and the results of reconstruction of fission products of nuclear fuel and products of activation of constructional materials distribution in the cross-section of the fuel assembly. The reconstruction results showed that the meltdown of the power rods’ fuel and of the internal casing’s part with corium formation had occurred in the investigated cross section of the fuel assembly. The conducted research proved the effectiveness of the used technique and the serviceability of the developed reconstruction algorithm. Citation: V.A. Zhitelev, E.A. Zvir, M.V. Kuprienko, A.V. Strozhuk, G.D. Nurullina, Emission gamma tomography of the test fuel assembly for BOR-60 reactor, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 73–81. DOI: 10.18721/JPM.10405 10.18721/JPM.10405 620.179.152.5 emission computer gamma tomography reconstruction algebraic iteration scheme test fuel assembly https://physmath.spbstu.ru/article/2017.38.5/ 05_73_81_10_4_2017.pdf

RAR RUS 82-91 Bodrov Alexander sales@plasmalabs.ru Zorkin Vladimir vladimir.zorkin@mail.ru Chulyaeva Elena Payurov Alexander mera@plasmalabs.ru Kyun Valerij kvazar@plasmalabs.ru Determination of harmonic noise components against the background of other types of laser noise The problem of research the reasons for limiting and reducing the stability of characteristics of coherent optical radiation sources is considered. The Experimental data are obtained by devises for measurement of power and frequency instability of laser radiation. Influence of laser radiation noise on stability of its parameters is revealed. The research are conducted by autocorrelation function and Allan variance. Pink noise, interference noise and other types of noise are found. Causes of noises are roughness of lasers tube cathode, material of devises for cavity adjustment, antireflection coating application and so on. Citation: A.I. Bodrov, V.S. Zorkin, E.G. Chulyaeva, A.Ya. Payurov, V.V. Kyun, Determination of harmonic noise components against the background of other types of laser noise, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 82–91. DOI: 10.18721/JPM.10406 10.18721/JPM.10406 621.373.826 noise frequency stabilized laser Allan variance autocorrelation function power instability https://physmath.spbstu.ru/article/2017.38.6/ 06_82_91_10_4_2017.pdf

RAR RUS 92-99 0000-0002-1213-4837 Kudyukin Alexander a.kudykin@rsu.edu.ru Borisovsky Pyotr borisovsky@physicist.net Gavrilov Sergey Gavrilov@physicist.net Makhmudov Marat Makhmudov@physicist.net 0000-0003-3831-7882 Ryazan State University named for S.A.Yesenin Moos Evgueniy e.moos@rsu.edu.ru Kiselyov Georgiy Kiselyov@physicist.net Kiselyova Lyudmila Kiselyova@physicist.net Ryazan State University named for S.A.Yesenin Stepanov Vladimir vl.stepanov@365.rsu.edu.ru Evolution features of laser electrode-surface morfology in the gas discharge plasma The effect of plasma flows on the cathode surface in the He-Ne plasma of a gas discharge has been investigated using X-ray photoelectron spectroscopy, the electron microprobe analysis, including atomic composition analysis in the depth profiling and in the raster mode. The studies were supplemented by modeling of the arc discharge in vacuum arc-quenching chambers up to the melting of the metal-alloyed electrodes based on the two-component systems under critical discharge rate (under increased power). In all instances there were identified the processes lead-ing to the degradation and destruction of the cathode surface. Method of electronic microprobe analysis revealed a change in the composition of chromium-copper alloy electrode in the depth due to thermal effects at all stages of production, testing and service. In the zone of the melted electrodes, we observed redistribution of the main components and a substantial decrease in the oxygen concentration. Citation: A.I. Kudyukin, P.A. Borisovsky, S.V. Gavrilov, M.N. Makhmudov, E.N. Moos, G.V. Kiselyov, L.I. Kiselyova, V.A. Stepanov, Evolution features of laser electrode-surface morfology in the gas discharge plasma, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 92–99. DOI: 10.18721/JPM.10407 10.18721/JPM.10407 533.9 plasma ion-plasma flow gas discharge ablation polycrystalline structure surface morphology https://physmath.spbstu.ru/article/2017.38.7/ 07_92_99_10_4_2017.pdf

SCO RUS 100-110 Zezina Tatiana zezinat@yandex.ru Peter the Great St. Petersburg Polytechnic University Tsybin Oleg otsybin@rphf.spbstu.ru Subpicosecond dynamics of the molecular polyalanine dipole moment Instantaneous dipole moments of polyalanine peptides in vacuum and in the aqueous medium have been calculated on the picosecond time scale in order to evaluate the external influence of temperature, of the electrostatic field’s amplitude and direction. Computer simulation was performed using the molecular dynamics method. The dynamic scenarios induced by the external electrostatic field above 100 MV/m were obtained for polyalanine molecules of different lengths (from 2 to 24 groups) placed in vacuum and in aqueous medium, the time step of 1 fs and the simulation time up to 100 ns being taken. The simulated scenarios can be used for a further analysis and a generalized description of structural properties and conformational dynamics of molecules. The mastered software packages are appropriate for computing the representational scenarios of biomolecular behavior under various conditions. Citation: T.I. Zezina, O.Yu. Tsybin, Subpicosecond dynamics of the molecular polyalanine dipole moment, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (3) (2017) 100–110. DOI: 10.18721/JPM.10408 10.18721/JPM.10408 539.2; 004.94 биомолекула пептиды компьютерное моделирование молекулярная динамика дипольный момент биомолекулярная электроника https://physmath.spbstu.ru/article/2017.38.8/ 08_100_110_10_4_2017.pdf

RAR RUS 111-123 Ovchinnikov Sergey sovichin@utk.edu Peter the Great St. Petersburg Polytechnic University Larionov Nikolay larionov.nickolay@gmail.com 0000-0001-7608-7120 Peter the Great St. Petersburg Polytechnic University Smirnovsky Alexander smirta@mail.ru Schmidt Alexander alexander.schmidt@mail.ioffe.ru Formation of quantum vortices upon atom ionization by a pulse of electromagnetic waves A numerical and analytical study of the space-time evolution of a quantum system formed as a result of the interaction of an electromagnetic pulse with a hydrogen-like atom in the two-dimensional approximation has been carried out. A characteristic feature of the obtained solution is the presence of singular points, the analysis of them was carried out through a probability density and a probability flux density. The vortices formed during the ionization can propagate to macroscopic distances and manifest themselves as forbidden domains in the spectrum of wave numbers. For numerical simulation of such a problem, a special transformation of variables (method of expanding space) was used. The numerical analysis of the quantum vortices number and its position was performed depending on electromagnetic field parameters. The numerical solution was compared with the analytical one obtained in the framework of the Born approximation. Citation: S.Yu. Ovchinnikov, N.V. Larionov, A.A. Smirnovsky, A.A. Schmidt, Formation of quantum vortices upon atom ionization by a pulse of electromagnetic waves, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 111–123. DOI: 10.18721/JPM.10409 10.18721/JPM.10409 530.145 quantum vortex atom ionization Shrödinger equation numerical simulation Born approximation https://physmath.spbstu.ru/article/2017.38.9/ 09_111_123_10_4_2017.pdf

RAR RUS 124-133 Kumar Vikas vikasmath81@gmail.com Kaur Lakhveer lakhveer712@gmail.com On the solutions of field equations due to rotating bodies in general relativity A metric, describing the field due to bodies in stationary rotation about their axes and compatible with a stationary electromagnetic field, has been studied in the present paper. Using the Lie symmetry reduction approach, we have herein examined, under continuous groups of transformations, the invariance of field equations due to rotation in General Relativity, which are expressed in terms of a coupled system of partial differential equations. We have exploited the symmetries of these equations to derive some ansatz leading to the reduction of variables, where the analytic solutions are easier to obtain by considering the optimal system of conjugacy inequivalent subgroups. Furthermore, some solutions are considered by using numerical methods due to complexity of reduced ordinary differential equations. Citation:V. Kumar, L. Kaur, On the solutions of field equations due to rotating bodies in General Relativity, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 124–133. DOI: 10.18721/JPM.10410 10.18721/JPM.10410 530.12:531.51 general relativity electromagnetic field Lie symmetry method exact solutions https://physmath.spbstu.ru/article/2017.38.10/ 10_124_133_10_4_2017.pdf

RAR RUS 134-142 Saxena Gaurav gauravphy@gmail.com Kaushik Manish mkaushik007@gmail.com N = 28 isotones: shape coexistence towards proton deficient side We have employed the RMF+BCS (relativistic mean-field plus BCS) approach to study the phenomenon of shape coexistence in N = 28 isotones towards the proton-deficient side. Our present investigations include single particle energies, deformations, binding energies as well as excitation energies. It is found that towards the proton-deficient side, N = 28 shell closure disappears due to reduced gap between neutron 1f7/2 and 1f5/2 and the nuclei 40Mg, 42Si, and 44S are found to possess shape coexistence, giving further support to weakening of the shell gap. These results are found to be in excellent agreement with other theoretical and experimental studies and are fortified with a variety of calculations and parameters. Citation: G. Saxena, M. Kaushik, M. Kumar, N = 28 isotones: shape coexistence towards proton deficient side, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (4) (2017) 134–142. DOI: 10.18721/JPM.10411 10.18721/JPM.10411 539.125 neutron magic nucleus relativistic mean-field plus BCS approach shape coexistence shell closure https://physmath.spbstu.ru/article/2017.38.11/ 11_134_142_10_4_2017.pdf