Труды сотрудников ИВМ СО РАН

[Текст] : статья / A.N. Rogalev // Optoelectronics, Instrumentation and Data Processing, Allerton Press. - 2011. - Vol. 47, Iss. 3. - p. 287-296, DOI 10.3103/S8756699011030125 . - ISSN 8756-6990
Аннотация: It is noted that, in many cases, object control is performed under conditions of a prior uncertainty in external actions and uncertainty in the current state of the object. Guaranteed methods are described which provide quantitative estimates of the boundaries of all possible phase states of a system taking into account all actions. Examples of calculations of inclusions of reachable sets are given.

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Доп.точки доступа:
Рогалев, Алексей Николаевич

/ V.V. Kuznetsov, V.K. Andreev // Thermophys. Aeromechanics. - 2013. - Vol. 20, Is. 1. - P17-28. - Cited References: 7. - The work was financially supported by the Russian Foundation for Basic Research (Grant No. 10-01-00007), Federal Target Program "Scientific and Scientific-Pedagogical Personnel of Innovative Russia" (State Contract 14.740.11.0355) and Program of Fundamental Research of OEM RAS No. 2.13.2. . - 12. - ISSN 0869-8643РУБ Thermodynamics + Mechanics

Аннотация: The problem of stabilized combined motion of the gas flow and liquid film in a microchannel under the action of local heating with consideration of evaporation processes was set in selected variables. The exact solutions to the linearized problem were derived. The analytical formulas for calculation of the film thickness stabilized below the heater and the total rate of liquid evaporation were obtained. The technique of approximate calculation of total heat transfer is shown. Exemplary calculations are presented.

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Kuznetsov, V.V.; Andreev, V.K.; Андреев, Виктор Константинович

/ 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.

/ O. V. Kaptsov // Program. Comput. Softw. - 2012. - Vol. 38, Is. 2. - pp. 102-104, DOI 10.1134/S0361768812020041. - Cited References: 15. - This work was supported by the Siberian Division of Russian Academy of Sciences (integration project no. 103) and by the Program for the Support of Leading Scientific Schools (project no. NSh 7256.2010.1). . - ISSN 0361-7688РУБ Computer Science, Software Engineering

Аннотация: In the paper, the Goursat problem-classification of nonlinear hyperbolic differential equations possessing two characteristic invariants-is considered. An algorithm for finding the characteristic invariants is described. On the basis of the algorithm implemented in REDUCE, the characteristic invariants of two Laine's equations are verified. One of them is shown to have invariants of the second and third orders. This equation shows that the Goursat problem, apparently, is still open. Computer calculations show that the characteristic invariants of the second Laine's equation given in his paper are incorrect.

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Капцов, Олег Викторович

[Text] / N.I. Kosarev, N.Y. Shaparev // J. Phys. B-At. Mol. Opt. Phys. - 2011. - Vol. 44, Is. 19. - Ст. 195402, DOI 10.1088/0953-4075/44/19/195402. - Cited References: 17 . - ISSN 0953-4075РУБ Optics + Physics, Atomic, Molecular & Chemical

Аннотация: Imprisonment of resonant radiation in an expanding sphere on the basis of the numerical solution of the rate balance equation for excited atoms and the transfer resonance radiation equation is investigated. Calculations of the escape factor for sphere at Doppler form of absorption and scattering profiles are executed. The effect of spectral shift of the absorption (emission) profile relative to the stationary one due to expansion of the medium is taken into account for the case when differential motion is described by velocity that varies linearly with the radius. The behaviour of the escape factor for the sphere is compared with the Sobolev theory. The numerical date for time dependence of intensity of afterglow and contour of the spectral line of leaving outside resonance radiation and spatial distribution of the excited atomic concentration are submitted as well.


Доп.точки доступа:
Shaparev, N.Ya.; Шапарев, Николай Якимович; Косарев Н.И.

[Text] / N.I. Kosarev, N.Y. Shaparev // J. Phys. B-At. Mol. Opt. Phys. - 2011. - Vol. 44, Is. 10. - Ст. 105402, DOI 10.1088/0953-4075/44/10/105402. - Cited References: 9 . - ISSN 0953-4075РУБ Optics + Physics, Atomic, Molecular & Chemical

Аннотация: Imprisonment of resonant radiation in gases on the basis of the numerical solution of the rate balance equation for the excited atoms and the transfer resonant radiation equation is investigated. Calculations of the escape factor for the slab, cylinder and sphere at Doppler and Lorentz forms of absorption and scattering profiles are executed. Calculation results of the escape factor for the cylinder and slab are compared with Holsten's asymptotical solutions. The numerical data for time dependence of a spectrum, the intensity of resonant radiation and the spatial distribution of the excited atomic concentration in a regime of afterglow are also considered.


Доп.точки доступа:
Shaparev, N.Ya.; Шапарев, Николай Якимович; Косарев Н.И.

[Text] / A. Divin [et al.] // Phys. Plasmas. - 2010. - Vol. 17, Is. 12. - Ст. 122102, DOI 10.1063/1.3521576. - Cited References: 42. - The present work is supported partially by the Onderzoekfonds KU Leuven (Research Fund KU Leuven) and by the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant Agreement No. 218816 (SOTERIA project, www.soteria- space.eu). Additional support is provided by RFBR (Grant No. 09-05-91000-ANF-a). V.S.S. thanks ISSI for hospitality and financial support. The simulations were conducted on the resources of the Vlaams Supercomputer Centrum (VSC) at the Katholieke Universiteit Leuven. . - ISSN 1070-664XРУБ Physics, Fluids & Plasmas

Аннотация: A new model of the electron pressure anisotropy in the electron diffusion region in collisionless magnetic reconnection is presented for the case of antiparallel configuration of magnetic fields. The plasma anisotropy is investigated as source of collisionless dissipation. By separating electrons in the vicinity of the neutral line into two broad classes of inflowing and accelerating populations, it is possible to derive a simple closure for the off-diagonal electron pressure component. The appearance of these two electron populations near the neutral line is responsible for the anisotropy and collisionless dissipation in the magnetic reconnection. Particle-in-cell simulations verify the proposed model, confirming first the presence of two particle populations and second the analytical results for the off-diagonal electron pressure component. Furthermore, test-particle calculations are performed to compare our approach with the model of electron pressure anisotropy in the inner electron diffusion region by Fujimoto and Sydora [Phys. Plasmas 16, 112309 (2009)]. (C) 2010 American Institute of Physics. [doi:10.1063/1.3521576]


Доп.точки доступа:
Divin, A.; Markidis, S.; Lapenta, G.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.

[Text] / P.V. Belolipetsky [et al.] // Aquat. Ecol. - 2010. - Vol. 44, Is. 3. - pp. 561-570, DOI 10.1007/s10452-010-9330-z. - Cited References: 35. - The study was financially supported by the Netherlands Organization for Scientific Research (NWO), Grant 047.011.2004.030, RFBR, Grant 05-05-89002; RFBR, Grant 07-01-00153; Multidisciplinary integration project of SB RAS No. 95. . - ISSN 1386-2588РУБ Ecology + Limnology + Marine & Freshwater Biology

Аннотация: A one-dimensional numerical model and a two-dimensional numerical model of the hydrodynamic and thermal structure of Lake Shira during summer have been developed, with several original physical and numerical features. These models are well suited to simulate the formation and dynamics of vertical stratification and provide a basis for an ecological water-quality model of the lake. They allow for the quantification of the vertical mixing processes that govern not only the thermal structure but also the nutrient exchange, and more generally, the exchange of dissolved and particulate matter between different parts of the lake. The outcome of the calculations has been compared with the field data on vertical temperature and salinity distributions in Lake Shira. Lake Shira is meromictic and exhibits very stable annual stratification. The stratification is so stable because of the high salinity of the water. If the water in Lake Shira were fresh and other parameters (depth, volume, and meteorology) were the same, as now, the lake would be mixed in autumn. Using the newly developed models and using common meteorological parameters, we conclude that Lake Shira will remain stratified in autumn as long as the average salinity is higher than 3%.


Доп.точки доступа:
Belolipetsky, P.V.; Белолипецкий, Павел Викторович; Belolipetskii, V.M.; Белолипецкий, Виктор Михайлович; Genova, S.N.; Генова, Светлана Николаевна; Mooij, W.M.

[Text] / M.P. Varygina, O.V. Sadovskaya, V.M. Sadovskii // J. Appl. Mech. Tech. Phys. - 2010. - Vol. 51, Is. 3. - pp. 405-413, DOI 10.1007/s10808-010-0055-5. - Cited References: 9. - This work was supported by the Russian Foundation for Basic Research (Grant No. 08-01-00148), the Complex Program of Basic Research of the Presidium of the Russian Academy of Sciences No. 2 Intelligent information technologies, mathematical modeling, system analysis and automation, and the interdisciplinary Integration project of the Siberian Division of the Russian Academy of Sciences No. 40. . - ISSN 0021-8944РУБ Mechanics + Physics, Applied

Аннотация: Using highly effective parallel calculations, it is shown that in a moment elastic medium, there is a resonant frequency which corresponds to the eigenfrequency of rotational motion of particles and does not depend on the size of the region studied.


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

[Text] / M. Ampferer [et al.] // Ann. Geophys. - 2010. - Vol. 28, Is. 3. - pp. 779-787. - Cited References: 30. - This work is supported by grants 07 05 00135, 09-06-91000 from the Russian Foundation for Basic Research and by the Program 16.3 of the Russian Academy of Sciences. Additional support is due to the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under Project I193-N16 and the "Verwaltungsstelle fur Auslandsbeziehungen" of the Austrian Academy of Sciences. The authors are grateful to the referees whose comments helped considerably to improve the paper. . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: It is well known that lithospheric electromagnetic emissions are generated before earthquakes occurrence. In our study, we consider the physical penetration mechanism of the electric field from the Earth's surface, through the atmosphere-ionosphere layers, and until its detection in space by satellites. A simplified approach is investigated using the electric conductivity equation, i.e., del((sigma) over cap.del Phi) = 0 in the case of a vertical inclination of the geomagnetic field lines. Particular interest is given to the conductivity profile near the ground and the electric field distribution at the Earth's surface. Our results are discussed and compared to the models of Pulinets et al. (2003) and Denisenko et al. (2008). It is shown that the near ground atmospheric layer with low conductivity decreases the electric field penetration into the ionosphere. The model calculations have demonstrated that the electric field of lithospheric origin is too weak to be observed at satellite altitudes.


Доп.точки доступа:
Ampferer, M.; Denisenko, V.V.; Денисенко, Валерий Васильевич; Hausleitner, W.; Krauss, S.; Stangl, G.; Boudjada, M.Y.; Biernat, H.K.

[Text] / A. P. Gavrilyuk, N. Y. Shaparev // Quantum Electron. - 2013. - Vol. 43, Is. 10. - P943-948, DOI 10.1070/QE2013v043n10ABEH015141. - Cited References: 18 . - ISSN 1063-7818РУБ Engineering, Electrical & Electronic + Physics, Applied

Аннотация: By means of numerical modelling of the combined effect of laser (1.06 mu m) and microwave (10(10)-10(13) s(-1)) radiation on the aluminium surface in vacuum it is shown that the additional action of microwave radiation with the frequency 10(12) s(-1) provides complete ionisation of the metal vapour (for the values of laser radiation duration and intensity used in the calculations), while in the absence of microwave radiation the vapour remains weakly ionised. The mathematical model used accounts for the processes, occurring in the condensed phase (heat conduction, melting), the evaporation and the kinetic processes in the resulting vapour.


Доп.точки доступа:
Shaparev, N.Ya.; Шапарев, Николай Якимович; Гаврилюк, Анатолий Петрович

[Text] / C. J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 2008. - Vol. 113. - Ст. A00B01, DOI 10.1029/2007JA012953. - Cited References: 38 . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: We identify a planar, pressure-balanced structure bounded by sharp changes in the dynamic pressure plastered against the front boundary of the magnetic cloud which passed Earth on 20 November 2003. The front boundary of the magnetic cloud (MC) is particularly well-defined in this case, being located where the He(++)/H(+) number density ratio jumps from 4 to 10% for the first time and the proton plasma beta decreases sharply from similar to 1 to similar to 0.001. The feature, estimated to have a length scale similar to 50 RE in the Sun-Earth direction, bears close resemblance to a slow mode transition region in that the magnetic pressure decreases, the plasma pressure increases, and their temporal variations are anticorrelated. Using a 2-D MHD simulation, we hypothesize that a pressure-balanced structure was encountered by the MC en route to Earth. Our calculations reproduce qualitatively the major features of the observations. Using a simplified geometry suggested by the observations, we find that the lateral deflection speed of the plasma is less than the lateral expansion speed of the MC. We infer that the structure traversed the MC sheath in similar to 20 h, consistent with its crossing of the MC's shock at 0.6-0.7 AU. The finding is consistent with the recent paradigm according to which solar wind plasma and magnetic field tend to pile up in front of interplanetary ejecta because the expansion of the ejecta hinders the shocked solar wind plasma from deflecting effectively around the object. Also, the inferred "age'' of the layer contiguous to the surface of the MC, the earliest relic of its passage through the inner heliosphere, is in agreement with general estimates.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Taubenschuss, U.; Shaidurov, V.A.; Smith, C.W.; Biernat, H.K.

[Text] / T. Penz [et al.] ; ed.: O. Witasse // PLANETARY ATMOSPHERES, IONOSPHERES, AND MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE LTD, 2005. - Vol. 36: 35th COSPAR Scientific Assembly (JUL 18-25, 2004, Paris, FRANCE), Is. 11. - P2049-2056, DOI 10.1016/j.asr.2004.11.039. - Cited References: 20 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: It is known from Pioneer Venus measurements that at the Venusian ionopause wave-like structures develop, which can detach in the form of ionospheric plasma clouds. This phenomenon is assumed to occur due to the Kelvin-Helmholtz instability, which can appear in large regions of the Venusian ionopause. Recent studies of Mars Global Surveyor measurements indicate that wave-like structures and plasma clouds also detach from the Martian ionopause. Therefore, these features seem to be common for the solar wind interaction of non-magnetized planets. We study the conditions at the Martian ionopause with respect to the occurrence of several MHD instabilities. The conditions in the magnetosheath are modeled by a semi-analytical MHD simulation that includes mass loading. The ionospheric parameter needed for the model calculations are taken from a global hybrid model. The stability of the Martian ionopause against the Kelvin-Helmholtz, the Rayleigh-Taylor, and the interchange instability is analyzed. Further, we suggest that including the Hall term in the description of the Kelvin-Helmholtz instability gives a current in the planetary boundary layer resulting in a shear flow compared with the ionospheric plasma, which can lead to an unstable boundary layer near the subsolar point. Since the interchange instability depends on the curvature of the magnetic field lines, we additionally study the influence of the strong curvature of the Martian ionopause due to the localized, remnant, crustal magnetism appearing mainly in the southern hemisphere of Mars. (c) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Penz, T.; Arshukova, I.L.; Terada, N.; Shinagawa, H.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Lammer, H.; Witasse, O. \ed.\

[Text] / D. F. Vogl [et al.] // Planet Space Sci. - 2003. - Vol. 51, Is. 12. - P715-722, DOI 10.1016/S0032-0633(03)00108-9. - Cited References: 28 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: In this paper, we concentrate on the analysis of the anisotropic Rankine-Hugoniot equations for perpendicular and oblique fast shocks. In particular, as additional information to the anisotropic set of equations, the threshold conditions of the fire-hose and mirror instability are used to bound the range of the pressure anisotropy downstream of the discontinuity. These anisotropic threshold conditions of the plasma instabilities are obtained via a kinetic approach using a generalized Lorentzian distribution function, the so-called kappa distribution function. Depending on up-stream conditions, these instabilities further define stable and unstable regions with regard to the pressure anisotropy downstream of the shock. The calculations are done for different upstream Alfven Mach numbers. We found that low values of the parameter kappa reduce the pressure anisotropy downstream of the shock. (C) 2003 Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Vogl, D.F.; Langmayr, D.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Farrugia, C.J.; Muhlbachler, S.

[Text] / N. V. Erkaev [et al.] // Planet Space Sci. - 2001. - Vol. 49, Is. 13. - P1359-1364, DOI 10.1016/S0032-0633(01)00057-5. - Cited References: 22 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: Spacecraft observations confirm the existence of mirror fluctuations in the magnetosheath. The mirror instability occurs in an anisotropic magnetized plasma when the difference between perpendicular and parallel (with respect to the magnetic field) plasma pressure exceeds a threshold depending on the perpendicular plasma beta. The anisotropy of the plasma pressure increases from the shock to the magnetopause as a result of magnetic field line stretching. This gives rise to plasma fluctuations which in turn lead to a relaxation between parallel and perpendicular temperatures. Mirror perturbations do not propagate and are convected with plasma flow along the streamlines. Using an anisotropic steady-state MHD flow model, we calculate the growth of mirror fluctuations from the bow shock to the magnetopause along the subsolar streamline. For the anisotropic MHD model, we use the empirical closure equation suitable for the AMPTE/IRM observations. The amplitudes of mirror fluctuations, which are obtained as a function of distance from the magnetopause, are directly compared with AMPTE/IRM observations on October 24, 1985. With regard to both the amplification of the magnetic field and the plasma density oscillations, as well as the location of maximum amplitudes, model calculations are in good agreement with values obtained from the AMPTE/IRM data. (C) 2001 Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Schaffenberger, W.; Biernat, H.K.; Farrugia, C.J.; Vogl, D.F.

[Text] / H. K. BIERNAT [et al.] // Planet Space Sci. - 1995. - Vol. 43, Is. 9. - P1105-1120, DOI 10.1016/0032-0633(95)00054-9. - Cited References: 31 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: We use the magnetohydrodynamic approach to calculate all plasma and magnetic field quantities along a line normal to the magnetopause, beginning at the bow shock, through the magnetosheath and magnetopause, and into the magnetosphere. Our method is based on a perturbation calculation, where we expand in orders of 1/M(A infinity), with M(A infinity) the Alfven Mach number upstream of the bow shock. The calculations are carried out (1) in the noon-midnight meridian at latitudes just south of the northern cusp, and (2) in the equatorial flank region. Our calculations are for an interplanetary magnetic field (IMF) which is directed perpendicular to the upstream solar wind. We consider two orientations of the IMF. In one case, the interplanetary field points due south, i.e. antiparallel to the magnetospheric field in the subsolar point. In the second case, it lies in the equatorial plane and points from dusk to dawn. For each of these different orientations of the IMF, in situ observations of reconnection have been made. In the magnetosheath region adjacent to the magnetopause, i.e. in the so-called magnetic barrier, the magnetic forces react back on the plasma flow. This effect is included consistently in the calculation by the use of a special coordinate system. The magnetic field tension accelerates the plasma in a direction perpendicular to the field and thus the magnetic field produces an asymmetry in the flow field. At the magnetopause we describe shock-type reconnection, taking as input on the magnetosheath side the results of the above calculation and taking at the magnetospheric side typical values for the outer boundary of the magnetosphere. The format in which the results are presented is similar to that used in the presentation of bulk parameters and magnetic field measurements obtained from spacecraft.


Доп.точки доступа:
BIERNAT, H.K.; BACHMAIER, G.A.; KIENDL, M.T.; Erkaev, N.V.; Еркаев, Николай Васильевич; MEZENTSEV, A.V.; FARRUGIA, C.J.; SEMENOV, V.S.; RIJNBEEK, R.P.

[Text] / V. V. Denisenko [et al.] // Ann. Geophys. - 2008. - Vol. 26, Is. 8. - P2111-2130. - Cited References: 19. - This work is supported by grant 07-05-00135 from the Russian Foundation for Basic Research, by the Programs 16.3 and 2.16 of the Russian Academy of Sciences, and by project I.2/04 from "Osterreichischer Austauschdienst". It is also supported by the Austrian "Fonds zur Forderung der wissenschaftlichen Forschung" under projects P17100-N08 and P20145-N16. We acknowledge support by the Austrian Academy of Sciences, "Verwaltungstelle fur Auslandsbeziehungen", and the Russian Academy of Sciences. . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: A quantitative division of the ionosphere into dynamo and motor regions is performed on the base of empirical models of space distributions of ionospheric parameters. Pedersen and Hall conductivities are modified to represent an impact of acceleration of the medium because of Ampere's force. It is shown that the currents in the F(2) layer are greatly reduced for processes of a few hours duration. This reduction is in particular important for the night-side low-latitude ionosphere. The International Reference Ionosphere model is used to analyze the effect quantitatively. This model gives a second high conducting layer in the night-side low-latitude ionosphere that reduces the electric field and equatorial electrojets, but intensifies night-side currents during the short-term events. These currents occupy regions which are much wider than those of equatorial electrojets. It is demonstrated that the parameter sigma(d)=sigma(P)+sigma(H)Sigma(H)/Sigma(P) that involves the integral Pedersen and Hall conductances Sigma(P), Sigma(H) ought to be used instead of the local Cowling conductivity sigma C in calculations of the electric current density in the equatorial ionosphere. We may note that Gurevich et al. (1976) derived a parameter similar to sigma(d) for more general conditions as those which we discuss in this paper; a more detailed description of this point is given in Sect. 6. Both, sigma(d) and sigma(C), appear when a magnetic field line is near a nonconducting domain which means zero current through the boundary of this domain. The main difference between sigma(d) and sigma(C) is that sigma d definition includes the possibility for the electric current to flow along a magnetic field line in order to close all currents which go to this line from neighboring ones. The local Cowling conductivity sigma(C) corresponds to the current closure at each point of a magnetic field line. It is adequate only for a magnetic field line with constant local conductivity at the whole line when field-aligned currents do not exist because of symmetry, but sigma(C)=sigma(d) in this case. So, there is no reason to use the local Cowling conductivity while the Cowling conductance Sigma(C)=Sigma(P)+Sigma(2)(H)/Sigma(P) is a useful and well defined parameter.


Доп.точки доступа:
Denisenko, V.V.; Денисенко, Валерий Васильевич; Biernat, H.K.; Mezentsev, A.V.; Shaidurov, V.A.; Zamay, S.S.

[Text] / V. V. DENISENKO, S. S. ZAMAY // Planet Space Sci. - 1992. - Vol. 40, Is. 7. - P941-952, DOI 10.1016/0032-0633(92)90134-A. - Cited References: 47 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: A model of the ionosphere as a global conductor is used to examine synchronous variations of electric fields and currents at high and low latitudes. The special form of a boundary value problem and a multigrid numerical method permit investigation of auroral field penetration to the equator. A model of field-aligned currents and conductivities for expansion and recovery phases of a substorm are suggested, which are in accordance with empirical models and with theory of field-aligned current dynamics. Electric field distributions near the equator, which were obtained as a result of calculations, are in accordance with observations during substorms. It is shown that the contribution of high latitude sources to low latitude electric fields and currents during quiet-time periods is comparable with that given by dynamo fields. The nature of the post-sunset peak of the zonal electric field at the equator and seasonal variations of this peak are explained.


Доп.точки доступа:
ZAMAY, S.S.; Денисенко, Валерий Васильевич

[Text] / I. I. Ryzhkov // Phys. Fluids. - 2011. - Vol. 23, Is. 8. - Ст. 82103, DOI 10.1063/1.3627150. - Cited References: 13. - This work is supported by the Interdisciplinary Project 116 of SB RAS and Russian President Grant No. MK-299.2009.1. . - ISSN 1070-6631РУБ Mechanics + Physics, Fluids & Plasmas

Аннотация: The study of convective thermocapillary instabilities in liquid bridges [J. J. Xu and S. H. Davis, Phys. Fluids 27(5), 1102 (1984)] is revisited. A new branch of neutral mode m = 1 is found. The previously reported results are confirmed in the range of low Prandtl numbers. It is shown that for large Prandtl numbers, the flow becomes unstable at much smaller values of the Marangoni number than it was reported previously. The calculations are performed for adiabatic and heat conductive free surface. In both cases, the critical mode is m = 1. The previously reported change of critical mode from m = 1 to m = 0 with increasing the Prandtl number is not confirmed. The corrected results provide a better agreement with the experimental data. (C) 2011 American Institute of Physics. [doi:10.1063/1.3627150]


Доп.точки доступа:
Рыжков, Илья Игоревич

[Text] : статья / V. B. Bekezhanova // Fluid Dynamics. - 2011. - Vol. 46, Iss. 4. - p. 525-535DOI 10.1134/S001546281104003X . -
Аннотация: A plane steady-state two-layer fluid flow under the coupled action of the buoyancy and Marangoni forces is considered. The system is oriented at an arbitrary angle with respect to the gravity force. Exact solutions generalizing the Ostroumov-Birikh solution are obtained and their stability is studied in the framework of a linear theory. On the basis of numerical calculations, the influence of the inclination angle, the thickness of the layers, and the wall heating conditions on the instability mechanisms is investigated.

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Бекежанова, Виктория Бахытовна