Труды сотрудников ИВМ СО РАН

[Текст] : статья / E. D. Karepova, E. Dementyeva // Parallel Computing Technologies. - 2011. - Vol. 6873. - p. 444-451. - (Lecture Notes in Computer Science)DOI 10.1007/978-3-642-23178-0_39 . -
Аннотация: The ill-posed inverse problem of propagation of long waves in a domain of arbitrary form with the sufficiently smooth boundary on a sphere is consider. Numerical solution is based on finite elements method. Parallel software using MPI is performed. We compared efficiency of two popular implementations of the MPI standard and studied the behavior of our software when using various ways of memory allocation.

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Dementyeva, E.V.; Дементьева, Екатерина Васильевна; Карепова, Евгения Дмитриевна

/ D.B. Korovinskiy [et al.] // J. Geophys. Res-Space Phys. - 2013. - Vol. 118, Is. 3. - P1146-1158, DOI 10.1002/jgra.50206. - Cited References: 39. - This work is supported by the Austrian Science Fund (FWF): I193-N16, by the Onderzoekfonds KU Leuven (Research Fund KU Leuven), by RFBR Grants 12-05-00918-a and 12-05-00152-a, and by SPSU Grants 11.38.47.2011 and 11.38.84.2012. The research has received funding also from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 269198-Geoplasmas (Marie Curie International Research Staff Exchange Scheme) and 218816 (SOTERIA project). The simulations were conducted on the resources of the Vlaams Supercomputer Centrum (VSC) at the Katholieke Universiteit Leuven. N.V.E., V.S.S. and D.B.K. thank also ISSI for hospitality and financial support. The authors thank reviewers for their comments, which gave us the substantial aid in preparing of this manuscript. . - 13. - ISSN 2169-9380РУБ Astronomy & Astrophysics

Аннотация: The paper presents the detailed numerical investigation of the "double-gradient mode," which is believed to be responsible for the magnetotail flapping oscillations-the fast vertical (normal to the layer) oscillations of the Earth's magnetotail plasma sheet with a quasiperiod similar to 100-200 s. The instability is studied using the magnetotail near-equilibrium configuration. For the first time, linear three-dimensional numerical analysis is complemented with full 3-D MHD simulations. It is known that the "double-gradient mode" has unstable solutions in the region of the tailward growth of the magnetic field component, normal to the current sheet. The unstable kink branch of the mode is the focus of our study. Linear MHD code results agree with the theory, and the growth rate is found to be close to the peak value, provided by the analytical estimates. Full 3-D simulations are initialized with the numerically relaxed magnetotail equilibrium, similar to the linear code initial condition. The calculations show that current layer with tailward gradient of the normal component of the magnetic field is unstable to wavelengths longer than the curvature radius of the field line. The segment of the current sheet with the earthward gradient of the normal component makes some stabilizing effect (the same effect is registered in the linearized MHD simulations) due to the minimum of the total pressure localized in the center of the sheet. The overall growth rate is close to the theoretical double-gradient estimate averaged over the computational domain.

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Доп.точки доступа:
Korovinskiy, D.B.; Divin, A.; Erkaev, N.V.; Еркаев, Николай Васильевич; Ivanova, V.V.; Ivanov, I.B.; Semenov, V.S.; Lapenta, G.; Markidis, S.; Biernat, H.K.; Zellinger, M.

/ C. J. Farrugia [et al.] // Sol. Phys. - 2012. - Vol. 281, Is. 1. - pp. 461-489, DOI 10.1007/s11207-012-0119-1. - Cited References: 53 . - 29. - ISSN 0038-0938РУБ Astronomy & Astrophysics

Аннотация: We discuss the temporal variations and frequency distributions of solar wind and interplanetary magnetic field parameters during the solar minimum of 2007-2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A. We find that the density and total field strength were significantly weaker than in the previous minimum. The Alfv,n Mach number was higher than typical. This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions. We then discuss two major aspects that this weak solar activity had on the magnetosphere, using data from Wind and ground-based observations: i) the dayside contribution to the cross-polar cap potential (CPCP), and ii) the shapes of the magnetopause and bow shock. For i) we find a low interplanetary electric field of 1.3 +/- 0.9 mV m(-1) and a CPCP of 37.3 +/- 20.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions. We suggest that the Alfven wave trains in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this three-year period. For ii) we determine 328 magnetopause and 271 bow shock crossings made by Geotail, Cluster 1, and the THEMIS B and C spacecraft during a three-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the three years under survey. We use the same numerical approach as in Fairfield's (J. Geophys. Res. 76, 7600, 1971) empirical model and compare our findings with three magnetopause models. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 R-E and 14.35 R-E, respectively. When comparing with Fairfield's (1971) classic result, we find that the subsolar magnetosheath is thinner by similar to 1 R-E. This is mainly due to the low dynamic pressure which results in a sunward shift of the magnetopause. The magnetopause is more flared than in Fairfield's model. By contrast the bow shock is less flared, and the latter is the result of weaker MHD forces.

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Farrugia, C.J.; Harris, B.; Leitner, M.; Mostl, C.; Galvin, A.B.; Simunac, K.D.C.; Torbert, R.B.; Temmer, M.B.; Veronig, A.M.; Erkaev, N.V.; Еркаев, Николай Васильевич; Szabo, A.; Ogilvie, K.W.; Luhmann, J.G.; Osherovich, V.A.

/ N.V. Erkaev, V.S. Semenov, H.K. Biernat // Phys. Plasmas. - 2012. - Vol. 19, Is. 6. - Ст. 62905, DOI 10.1063/1.4725506. - Cited References: 22. - This work is supported by RFBR Grants Nos. 12-05-00152-a and 12-05-00918-a, and also by St. Petersburg University grant. V. S. S. and H. K. B. are supported from the FP7 Programme under Grant No. 269198-Geoplasmas (Marie Curie Exchange Scheme). Additional support is due to the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. . - ISSN 1070-664XРУБ Physics, Fluids & Plasmas

Аннотация: Magnetic filament approach is applied for modeling of nonlinear "kink"-like flapping oscillations of thin magnetic flux tubes in the Earth's magnetotail current sheet. A discrete approximation for the magnetic flux tube was derived on a basis of the Hamiltonian formulation of the problem. The obtained system of ordinary differential equations was integrated by method of Rosenbrock, which is suitable for stiff equations. The two-dimensional exact Kan's solution of the Vlasov equations was used to set the background equilibrium conditions for magnetic field and plasma. Boundary conditions for the magnetic filament were found to be dependent on the ratio of the ionospheric conductivity and the Alfven conductivity of the magnetic tube. It was shown that an enhancement of this ratio leads to the corresponding increase of the frequency of the flapping oscillations. For some special case of boundary conditions, when the magnetic perturbations vanish at the boundaries, the calculated frequency of the "kink"-like flapping oscillations is rather close to that predicted by the "double gradient" analytical model. For others cases, the obtained frequency of the flapping oscillations is somewhat larger than that from the "double gradient" theory. The frequency of the nonlinear flapping oscillations was found to be a decreasing function of the amplitude. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4725506]


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

/ V. M. Sadovskii, O. V. Sadovskaya ; ed. by T.E.Simos [et al.] // NUMERICAL ANALYSIS AND APPLIED MATHEMATICS (ICNAAM 2012), VOLS A AND B. Ser. AIP Conference Proceedings : AMER INST PHYSICS, 2012. - Vol. 1479: International Conference of Numerical Analysis and Applied Mathematics (ICNAAM) (SEP 19-25, 2012, Kos, GREECE). - pp. 1611-1614, DOI 10.1063/1.4756474. - Cited References: 4 . - ISBN 0094-243X. - ISBN 978-0-7354-1091-6РУБ Mathematics, Applied + Physics, Applied

Аннотация: Parallel program systems for numerical solution of 2D and 3D problems of the dynamics of deformable media with constitutive relationships of rather general form on the basis of universal mathematical model describing small strains of elastic, elastic-plastic and granular materials are worked out. Some computations of dynamic problems with and without taking into account the moment properties of a material were performed on supercomputers with cluster architecture.

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Доп.точки доступа:
Sadovskii, V.M.; Садовский, Владимир Михайлович; Sadovskaya, O.V.; Садовская, Оксана Викторовна; Simos, T.E. \ed.\; Psihoyios, G. \ed.\; Tsitouras, C. \ed.\

[Text] / N.V. Erkaev, V.S. Semenov, H.K. Biernat // Phys. Plasmas. - 2010. - Vol. 17, Is. 6. - Ст. 60703, DOI 10.1063/1.3439687. - Cited References: 15. - This work is supported by RFBR (Grant Nos. N 07-05-00776-a and N 09-05-91000-ANF_a), and by Program No. 16 of RAS. Additional support is due to the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project No. I 193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. . - ISSN 1070-664XРУБ Physics, Fluids & Plasmas

Аннотация: Hall magnetohydrodynamic model is investigated for current sheet flapping oscillations, which implies a gradient of the normal magnetic field component. For the initial undisturbed current sheet structure, the normal magnetic field component is assumed to have a weak linear variation. The profile of the electric current velocity is described by hyperbolic functions with a maximum at the center of the current sheet. In the framework of this model, eigenfrequencies are calculated as functions of the wave number for the "kink" and "sausage" flapping wave modes. Because of the Hall effects, the flapping eigenfrequency is larger for the waves propagating along the electric current, and it is smaller for the opposite wave propagation with respect to the current. The asymmetry of the flapping wave propagation, caused by Hall effects, is pronounced stronger for thinner current sheets. This is due to the Doppler effect related to the electric current velocity. (C) 2010 American Institute of Physics. [doi:10.1063/1.3439687]


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

/ O. V. Sadovskaya // Proceedings of XLI International Summer School–Conference APM 2013. - 2013. - P484-491
Аннотация: Mathematical model for the description of deformation of a porous metal is constructed on the basis of generalized rheological method. In this method a new rheological element, so-called rigid contact, is used to describe the uniaxial deformation of materials with different resistance to tension and compression. Change in the resistance of a porous metal to external loads, when the collapse of pores occurs, is taken into account by means of the von Mises–Schleicher strength condition. Irreversible deformation is described with the help of yield condition, modeling the plastic loss of stability of porous skeleton. For a homogeneous porous medium the fields of displacements and stresses in the problem of radial expansion of spherical and cylindrical cavities under the action of internal pressure considering the effect of collapse of pores are constructed in closed form. The algorithm of numerical realization of the model of dynamic deformation of metal foams on multiprocessor computer systems of the cluster type is worked out

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ИВМ СО РАН : 660036, Красноярск, Академгородок, 50, стр.44

Доп.точки доступа:
Садовская, Оксана Викторовна

[Text] / N. V. Erkaev, V. S. Semenov, H. K. Biernat // Geophys. Res. Lett. - 2008. - Vol. 35, Is. 2. - Ст. L02111, DOI 10.1029/2007GL032277. - Cited References: 13 . - ISSN 0094-8276РУБ Geosciences, Multidisciplinary

Аннотация: A new kind of magnetohydrodynamic waves are analyzed for a current sheet in a presence of a small normal magnetic field component varying along the sheet. As a background, two simplified models of a current sheet are considered with a uniform and nonuniform current distributions in the current sheet. On a basis of these two models, the flapping-type waves are obtained which are related to a coexistence of two gradients of the tangential and normal magnetic field components along the normal and tangential directions with respect to the current sheet. A stable situation for the current sheet is associated with a positive result of the multiplication of the two magnetic gradients, and unstable ( wave growth) condition corresponds to a negative result of the product. In the stable region, the "kink''-like wave mode is interpreted as so called flapping waves observed in the Earth's magnetotail current sheet.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

[Text] / N. V. Erkaev, V. S. Semenov, H. K. Biernat // Phys. Rev. Lett. - 2007. - Vol. 99, Is. 23. - Ст. 235003, DOI 10.1103/PhysRevLett.99.235003. - Cited References: 10 . - ISSN 0031-9007РУБ Physics, Multidisciplinary

Аннотация: A new kind of magnetohydrodynamic instability and waves are analyzed for a current sheet in the presence of a small normal magnetic field component varying along the sheet. These waves and instability are related to the existence of two gradients of the tangential (B(tau)) and normal (B(n)) magnetic field components along the normal (del(n)B(tau)) and tangential (del(tau)B(n)) directions with respect to the current sheet. The current sheet can be stable or unstable if the multiplication of two magnetic gradients is positive or negative. In the stable region, the kinklike wave mode is interpreted as so-called flapping waves observed in Earth's magnetotail current sheet. The kink wave group velocity estimated for the Earth's current sheet is of the order of a few tens of kilometers per second. This is in good agreement with the observations of the flapping motions of the magnetotail current sheet.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

[Text] / S. . Muhbachler [et al.] // Adv. Space Res. - 2009. - Vol. 43, Is. 10. - P1588-1593, DOI 10.1016/j.asr.2009.01.012. - Cited References: 11. - For the provision of prime parameter data the authors thank the instrument teams of Cluster-CIS, -FGM, -PEACE, and -STAFF, in particular I. Danduras, E. Lucek, A. Fazakerley, and N. Cornilleau-Wehrlin. This work is partly supported by ESTEC Contract 18.201/04/NL/NR, by DLR Grant 50 OC 0003, by RFBR Grant 04-05-64088, by Programs 2.17 and 16.3 of RAS, and by Project PI7100-N08 of the Austrian Science Fund. . - ISSN 0273-1177РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: This study presents several observations of the Cluster spacecraft on September 24, 2003 around 15:10 UT, which show necessary prerequisites and consequences for the formation of the so-called modified-two-stream instability (MTSI). Theoretical studies suggest that the plasma is MTSI unstable if (1) a relative drift of electrons and ions is present, which exceeds the Alfven speed, and (2) this relative drift or current is in the cross-field direction. As consequences of the formation of a MTSI one expects to observe (1) a field-aligned electron beam, (2) heating of the plasma, and (3) an enhancement in the B-wave spectrum at frequencies in the range of the lower-hybrid-frequency (LHF). In this study we use prime parameter data of the CIS and PEACE instruments onboard the Cluster spacecraft to verify the drift velocities of ions and electrons, FGM data to calculate the expected LHF and Alfven velocity, and the direction of the current. The B-wave spectrum is recorded by the STAFF instrument of Cluster. Finally, a field aligned beam of electrons is observed by 3D measurements of the IES instrument of the RAPID unit. Observations are verified using a theoretical model showing the build-up of a MTSI under the given circumstances. (C) 2009 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Muhbachler, S.; Langmayr, D.; Lui, ATY; Erkaev, N.V.; Еркаев, Николай Васильевич; Alexeev, I.V.; Daly, P.W.; Biernat, H.K.; ESTEC [18.201/04/NL/NR]; DLR [50 OC 0003]; RFBR [04-05-64088]; Austrian Science Fund [PI7100-N08]

[Text] / N. V. Erkaev [et al.] // J. Geophys. Res-Space Phys. - 2009. - Vol. 114. - Ст. A03206, DOI 10.1029/2008JA013728. - Cited References: 24. - We thank V. Sergeev for fruitful discussions and help in the preparation of the manuscript. This work is supported by RFBR grants N 07-05-00776-a, N 07-05-00135, by programs 2.16 and 16.3 of RAS, and by project P20341-N16 from the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung,'' and also by project I.2/04 from "Osterreichischer Austauschdienst.'' . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: A new kind of magnetohydrodynamic waves is analyzed for a current sheet in the presence of a small normal magnetic field component (B-z) varying along the sheet. For the initial undisturbed state, a simplified model of the current sheet is considered with a Harris-like current density distribution across the sheet. Within the framework of this model, an analytical solution is obtained for the flapping-type wave oscillations and instability, related to the gradient of the normal magnetic field component along the current sheet. The flapping wave frequency is found to be a function of the wave number, which has an asymptotic saturation for large wave numbers. This frequency is pure real in a stable situation for the magnetotail current sheet, when the Bz component increases toward Earth. The current sheet becomes unstable in some regions, where the Bz component decreases locally toward Earth. In the stable region, the "kink''-like wave oscillations are calculated for an initial Gaussian perturbation localized to the center of the current sheet. The flapping wave propagations are analyzed for two cases: (1) the initial perturbation is fixed, and (2) the source is moving toward Earth. In the last case, the Mach cone is obtained for the propagating flapping waves. The source for the flapping waves is associated with the fast plasma flow originated from the reconnection region.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Kubyshkin, I.V.; Kubyshkina, M.V.; Biernat, H.K.; RFBR [N 07-05-00776-a, N 07-05-00135]; Austrian "Fonds zur Forderung der wissenschaftlichen Forschung,'' [P20341-N16]

[Text] / N. V. Erkaev [et al.] // Ann. Geophys. - 2009. - Vol. 27, Is. 1. - P417-425. - Cited References: 24. - We thank V. Sergeev for fruitful discussions and help in preparation of the manuscript. This work is supported by RFBR grants N07-05-00776-a, N 07-05-00135, by SFU grant N 10, by Programs 2.16 and 16.3 of RAS, and by project P20341-N16 from the Austrian " Fonds zur Forderung der wissenschaftlichen Forschung", and also by project I.2/04 from "Osterreichischer Austauschdienst". . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: One-fluid ideal MHD model is applied for description of current sheet flapping disturbances appearing due to a gradient of the normal magnetic field component. The wave modes are studied which are associated to the flapping waves observed in the Earth's magnetotail current sheet. In a linear approximation, solutions are obtained for model profiles of the electric current and plasma densities across the current sheet, which are described by hyperbolic functions. The flapping eigenfrequency is found as a function of wave number. For the Earth's magnetotail conditions, the estimated wave group speed is of the order of a few tens kilometers per second. The current sheet can be stable or unstable in dependence on the direction of the gradient of the normal magnetic field component. The obtained dispersion function is used for calculation of the flapping wave disturbances, which are produced by the given initial Gaussian perturbation at the center of the current sheet and propagating towards the flanks. The propagating flapping pulse has a smooth leading front, and a small scale oscillating trailing front, because the short wave oscillations propagate much slower than the long wave ones.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Kubyshkin, I.V.; Kubyshkina, M.V.; Biernat, H.K.; RFBR [N07-05-00776-a, N 07-05-00135]; SFU [N 10]; RAS [2.16, 16.3]; Austrian " Fonds zur Forderung der wissenschaftlichen Forschung" [P20341-N16]; Osterreichischer Austauschdienst [I.2/04]

[Text] / D. B. Korovinskiy [et al.] // J. Geophys. Res-Space Phys. - 2011. - Vol. 116. - Ст. A05219, DOI 10.1029/2010JA015942. - Cited References: 45. - This work is supported by the Austrian Science Fund under projects I193-N16 and P21051-N16, by RFBR grant 09-05-91000-ANF-a, and by SPSU grant 11.38.47.2011. V. S. Semenov also thanks ISSI for hospitality and financial support. . - ISSN 2169-9380РУБ Astronomy & Astrophysics

Аннотация: A 2.5-D analytical electron Hall magnetohydrodynamic model of steady state magnetic reconnection in a collisionless compressible plasma with a constant electron temperature is developed. It is shown that as in the incompressible case, the solution of the Grad-Shafranov equation for the magnetic potential is a basis for the problem analysis. The formation of the double electric layers and layers of low-density plasma, mapping the magnetic separatrices, are investigated. It is found that the formation of depletion layers should not be governed by the out-of-plane magnetic field, but rather, the origin of these layers lies inside the electron diffusion region. The double electric layers are found to be thin separatrices-elongated sheets, whose cross sections are of the order of the electron diffusion region half width. These charged layers provide the presence of the strong electric field orthogonal to the in-plane projection of the magnetic field, which forces electrons to accelerate into the out-of-plane direction. Outside of the double electric layers, the condition of quasi-neutrality of the plasma is found to be fulfilled to high accuracy.


Доп.точки доступа:
Korovinskiy, D.B.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Divin, A.V.; Biernat, H.K.; Mostl, U.V.

[Text] / D. B. Korovinskiy [et al.] // Adv. Space Res. - 2011. - Vol. 48, Is. 9. - P1531-1536, DOI 10.1016/j.asr.2011.07.008. - Cited References: 12. - This work is supported by the Austrian Science Fund under project 1193-N16, by RFBR Grant No. 09-05-91000-ANF-a, by SPSU grant No. 11.38.47.2011, and by the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement No. 269198 - Geoplasmas (Marie Curie International Research Staff Exchange Scheme). V.S. Semenov thanks also ISSI for hospitality and financial support. . - ISSN 0273-1177РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: A linear MHD instability of the electric current sheet, characterized by a small normal magnetic field component, varying along the sheet, is investigated. The tangential magnetic field component is modeled by a hyperbolic function, describing Harris-like variations of the field across the sheet. For this problem, which is formulated in a 3D domain, the conventional compressible ideal MHD equations are applied. By assuming Fourier harmonics along the electric current, the linearized 3D equations are reduced to 2D ones. A finite difference numerical scheme is applied to examine the time evolution of small initial perturbations of the plasma parameters. This work is an extended numerical study of the so called "double gradient instability", - a possible candidate for the explanation of flapping oscillations in the magnetotail current sheet, which has been analyzed previously in the framework of a simplified analytical approach for an incompressible plasma. The dispersion curve is obtained for the kink-like mode of the instability. It is shown that this curve demonstrates a quantitative agreement with the previous analytical result. The development of the instability is investigated also for various enhanced values of the normal magnetic field component. It is found that the characteristic values of the growth rate of the instability shows a linear dependence on the square root of the parameter, which scales uniformly the normal component of the magnetic field in the current sheet. (C) 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Korovinskiy, D.B.; Ivanova, V.V.; Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Ivanov, I.B.; Biernat, H.K.; Zellinger, M.

[Text] / D. I. Kubyshkina [et al.] // J. Geophys. Res-Space Phys. - 2014. - Vol. 119, Is. 4. - P. 3002-3015, DOI 10.1002/2013JA019477. - Cited References: 32. - We thank C. W. Carlson and J. P. McFadden for use of THEMIS ESA data; K. H. Glassmeier, U. Auster, and W. Baumjohann for the use of FGM data provided under the lead of the Technical University of Braunschweig and with financial support through the German Ministry for Economy and Technology and the German Center for Aviation and Space (DLR) under contract 50 OC 0302. The work was partly supported by SPbU grant 11.38.84.12, by RFBR grants 12-05-00152-a and 12-05-00918-a, and by the grant for support of leading Scientific schools 2836.2014.5. The work of S. Dubyagin and N. Ganushkina was partly supported by the Academy of Finland. This work was supported by the Austrian Science Fund (FWF): I193-N16. N. V. E acknowledges the support by the International Space Science Institute (ISSI, Switzerland) and discussions within the ISSI Team 214 on Flow-Driven Instabilities of the Sun-Earth System. The research has received funding also from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 269198-Geoplasmas (Marie Curie International Research Staff Exchange Scheme) and 218816 (SOTERIA project). . - ISSN 2169-9380. - ISSN 2169-9402РУБ Astronomy & Astrophysics

Аннотация: Flapping waves are most noticeable large-scale perturbations of the magnetotail current sheet, whose nature is still under discussion. They represent rather slow (an order of magnitude less than typical Alfven speed) waves propagating from the center of the sheet to its flanks with a typical speed of 20-60 km/s, amplitude of 1-2 R-e and quasiperiod of 2-10 min. The double-gradient MHD model, which was elaborated in Erkaev et al. (2007) predicts two (kink and sausage) modes of the flapping waves with differences in their geometry and propagation velocity, but the mode structure is hard to resolve observationally. We investigate the possibility of mode identification by observing the rotation of magnetic field and plasma velocity vectors from a single spacecraft. We test theoretical results by analyzing the flapping oscillations observed by Time History of Events and Macroscale Interactions during Substorms spacecraft and confirm that character of observed rotation is consistent with kink mode determination made by using multispacecraft methods. Also, we checked how the existence of some obstructive conditions, such as noise, combined modes, and multiple sources of the flapping oscillations, can affect on the possibility of the modes separation with suggested method.

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ИВМ СО РАН

Доп.точки доступа:
Kubyshkina, D.I.; Sormakov, D.A.; Sergeev, V.A.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kubyshkin, I.V.; Ganushkina, N.Y.; Dubyagin, S.V.; German Ministry for Economy and Technology; German Center for Aviation and Space (DLR) [50 OC 0302]; SPbU [11.38.84.12]; RFBR [12-05-00152-a, 12-05-00918-a]; grant for support of leading Scientific schools [2836.2014.5]; Academy of Finland; Austrian Science Fund (FWF) [I193-N16]; International Space Science Institute (ISSI, Switzerland); European Union [269198, 218816]

[Text] / O. V. Sadovskaya, V. M. Sadovskii, M. P. Varygina // ECCOMAS Thematic Conference - COMPDYN 2013: 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, Proceedings - An IACM Special Interest Conference. - 2013. - P4578-4592
Аннотация: In the framework of mathematical model of a block medium with elastic blocks interacting through compliant viscoelastic interlayers and its approximation on the basis of equations of the Cosserat continuum, the problems of periodic perturbation of a layer and of a half-space under the action of distributed and localized surface loads are solved numerically. The simple formulas are suggested to determine the elasticity coefficients of the moment continuum by given characteristics of the materials of blocks and interlayers, which provide a good correspondence of the wave fields received by means of the exact and approximate models. Parallel computational algorithms, based on models of the inhomogeneous elasticity theory and the Cosserat elasticity theory, are applied to the analysis of propagation of elastic waves in geomaterials with layered and block microstructure. These algorithms are realized as parallel program systems for GPUs (using CUDA technology) and for multiprocessor computers of the cluster type (using MPI library). Monotone grid-characteristic schemes with a balanced number of time steps in elastic layers or blocks and in viscoelastic interlayers are used. By the analysis of numerical solutions it is shown that the multiblock medium has a resonant frequency of rotational motion of blocks, and this frequency does not depend on the size of a massif and on the boundary conditions at its surface.

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Доп.точки доступа:
Sadovskii, V.M.; Садовский, Владимир Михайлович; Varygina, M.P.; Варыгина, Мария Петровна; Садовская, Оксана Викторовна

[Text] / O. V. Sadovskaya, V. M. Sadovskii // AIP Conference Proceedings. - 2015. - Vol. 1648: International Conference on Numerical Analysis and Applied Mathematics (SEP 22-28, 2014, Rhodes, GREECE). - Ст. UNSP 630006, DOI 10.1063/1.4912864. - Cited References:5 . - ISSN 0094-243XРУБ Mathematics, Applied + Physics, Applied

Аннотация: Wave processes in blocky media with a large number of elastic blocks, interacting through compliant interlayers, are described by the equations of a piecewise-homogeneous isotropic elastic medium and by the equations of an orthotropic Cosserat continuum. Parallel program systems for numerical implementation of 2D dynamic problems on wave propagation in blocky media are worked out. Computations demonstrating the anisotropy of a blocky medium even for a sufficiently small thickness of interlayers were performed on supercomputers with cluster architecture.

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Держатели документа:
SB RAS, Inst Computat Modeling, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Sadovskaya, O.V.; Садовская, Оксана Викторовна; Sadovskii, V.M.; Садовский, Владимир Михайлович

[Text] / V. M. Sadovskii, O. V. Sadovskaya // AIP Conference Proceedings. - 2015. - Vol. 1648: International Conference on Numerical Analysis and Applied Mathematics (SEP 22-28, 2014, Rhodes, GREECE). - Ст. UNSP 630005, DOI 10.1063/1.4912863. - Cited References:6 . - ISSN 0094-243XРУБ Mathematics, Applied + Physics, Applied

Аннотация: Mathematical model for the description of deformation of a porous metal is constructed on the basis of generalized rheological method, taking into account change in the resistance to external loads, when the collapse of pores occurs. Irreversible deformation is described with the help of yield condition, modeling the plastic loss of stability of a porous skeleton. For a homogeneous porous medium the fields of displacements and stresses in the problem of radial expansion of spherical and cylindrical cavities under the action of internal pressure considering the effect of collapse of pores are constructed in closed form. The algorithm of numerical realization of the model of dynamic deformation of metal foams on multiprocessor computer systems of the cluster type is worked out.

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Держатели документа:
SB RAS, Inst Computat Modeling, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Sadovskii, V.M.; Садовский, Владимир Михайлович; Sadovskaya, O.V.; Садовская, Оксана Викторовна

[Text] / I. V. Krasnov // Chin. Phys. B. - 2015. - Vol. 24, Is. 6. - Ст. 063701, DOI 10.1088/1674-1056/24/6/063701. - Cited References:22 . - ISSN 1674-1056. - ISSN 1741-4199РУБ Physics, Multidisciplinary

Аннотация: Conditions have been studied under which a polychromatic optical superlattice can form and trap the Coulomb cluster of two strongly interacting ions. In our previous work (Krasnov I V and Kamenshchikov L P 2014 Opt. Comm. 312 192) this new all-optical method of obtaining and confining the Coulomb clusters was demonstrated by numerical simulations for special values of the optical superlattice parameters and in the case of Yb ions. In the present paper the conditions are explicitly formulated, under which the long-lived two-ion cluster in the superlattice cell is formed. The peculiarity of these conditions is the renormalization of the ion-ion Coulomb interaction. Notably, the renormalized Coulomb force is determined by the effective charge which depends on the light field parameters and can strongly differ from the "bare" ion charge. This result can be accounted for by the combined manifestation of the quantum fluctuations of optical forces, nonlinear dependence of these forces on the velocity, and non-Maxwellian (Tsallis type) velocity distribution of the ions in the optical superlattice. Explicit analytical formulas are also obtained for the parameters of the optical two-ion cluster.

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Держатели документа:
Russian Acad Sci, Siberian Div, Inst Computat Modeling, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Krasnov, I.V.; Краснов, Игорь Васильевич

/ M. Sadovsky [et al.] // Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - 2015. - Vol. 9043: 3rd International Work Conference on Bioinformatics and Biomedical Engineering, IWBBIO 2015; Granada; Spain; 15 April 2015 through 17 April 2015; Code 125929. - P481-490 . -
Аннотация: We studied the relations between the triplet frequency dictionaries of organelle genome, and the phylogeny of their bearers. The clusters in 63-dimensional space were identified through K-means, and the clade composition of those clusters has been investigated. Very high regularity in genomes distribution among the clusters was found, in terms of taxonomy. The strong synchrony in evolution of nuclear and organelle genomes manifests through this correlation: the proximity in frequency space was determined over the organelle genomes, while the proximity in taxonomy was determined morphologically. Similar effect is also found in the ensembles of other (say, yeast) genomes. © Springer International Publishing Switzerland 2015.

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Держатели документа:
Institute of Computational Modelling of SB RAS, Akademgorodok, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Sadovsky, M.G.; Садовский, Михаил Георгиевич; Putintseva, Y.; Chernyshova, A.; Fedotova, V.