Труды сотрудников ИВМ СО РАН

[Text] / C.J. Farrugia [et al.] // J. Geophys. Res-Space Phys. - 2010. - Vol. 115. - Ст. A08227, DOI 10.1029/2009JA015128. - Cited References: 34. - The authors would like to thank David Burgess for helpful discussions. Part of this work was done when NVE was on a research visit to the Space Science Center of the University of New Hampshire, USA. This work is supported by NASA grants NNX08AD11G and NNG06GD41G, and also by RFBR grants 07-05-00135, 09-05-91000-ANF_a and by Program 16 of RAS. R. P. Lin has been supported in part by NASA grant NNX08AE34G at UC Berkeley, and the WCU grant (R31-10016) funded by the Korean Ministry of Education, Science and Technology. We thank D. J. McComas and H. J. Singer for the ACE plasma data and GOES magnetic field data, respectively, obtained through NASA cdaweb site. . - ISSN 0148-0227РУБ Astronomy & Astrophysics

Аннотация: While there are many approximations describing the flow of the solar wind past the magnetosphere in the magnetosheath, the case of perfectly aligned (parallel or antiparallel) interplanetary magnetic field (IMF) and solar wind flow vectors can be treated exactly in a magnetohydrodynamic (MHD) approach. In this work we examine a case of nearly-opposed (to within 15) interplanetary field and flow vectors, which occurred on October 24-25, 2001 during passage of the last interplanetary coronal mass ejection in an ejecta merger. Interplanetary data are from the ACE spacecraft. Simultaneously Wind was crossing the near-Earth (X similar to -13 Re) geomagnetic tail and subsequently made an approximately 5-hour-long magnetosheath crossing close to the ecliptic plane (Z = -0.7 Re). Geomagnetic activity was returning steadily to quiet, "ground" conditions. We first compare the predictions of the Spreiter and Rizzi theory with the Wind magnetosheath observations and find fair agreement, in particular as regards the proportionality of the magnetic field strength and the product of the plasma density and bulk speed. We then carry out a small-perturbation analysis of the Spreiter and Rizzi solution to account for the small IMF components perpendicular to the flow vector. The resulting expression is compared to the time series of the observations and satisfactory agreement is obtained. We also present and discuss observations in the dawnside boundary layer of pulsed, high-speed (v similar to 600 km/s) flows exceeding the solar wind flow speeds. We examine various generating mechanisms and suggest that the most likely cause is a wave of frequency 3.2 mHz excited at the inner edge of the boundary layer by the Kelvin-Helmholtz instability.


Доп.точки доступа:
Farrugia, C.J.; Erkaev, N.V.; Еркаев, Николай Васильевич; Torbert, R.B.; Biernat, H.K.; Gratton, F.T.; Szabo, A.; Kucharek, H.; Matsui, H.; Lin, R.P.; Ogilvie, K.W.; Lepping, R.P.; Smith, C.W.

[Text] / C. J. Farrugia [et al.] // Ann. Geophys.-Atmos. Hydrospheres Space Sci. - 1998. - Vol. 16, Is. 5. - P518-527, DOI 10.1007/s00585-998-0518-7. - Cited References: 24 . - ISSN 0992-7689РУБ Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We compare numerical results obtained from a steady-state MHD model of solar wind flow past the terrestrial magnetosphere with documented observations made by the AMPTE!IRM spacecraft on 24 October, 1985, during an inbound crossing of the magnetosheath. Observations indicate that steady conditions prevailed during this about 4 hour-long crossing. The magnetic shear at spacecraft entry into the magnetosphere was 15 degrees. A steady density decrease and a concomitant magnetic field pile-up were observed during the 40 min interval just preceding the magnetopause crossing. In this plasma depletion layer (1) the plasma beta dropped to values below unity; (2) the flow speed tangential to the magnetopause was enhanced; and (3) the local magnetic field and velocity vectors became increasingly more orthogonal to each other as the magnetopause was approached (Phan er al., 1994). We model parameter variations along a spacecraft orbit approximating that of AMPTE/IRM, which was at slightly southern GSE latitudes and about 1.5 h post-noon Local Time. We model the magnetopause as a tangential discontinuity, as suggested by the observations, and take as input solar wind parameters those measured by AMPTE/IRM just prior to its bow shock crossing. We find that computed field and plasma profiles across the magnetosheath and plasma depletion layer match all observations closely. Theoretical predictions on stagnation line flow near this low-shear magnetopause are confirmed by the experimental findings. Our theory does not give, and the data on this pass do not show, any localized density enhancements in the inner magnetosheath region just outside the plasma depletion layer.


Доп.точки доступа:
Farrugia, C.J.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kistler, L.M.; Le, G.; Russell, C.T.

[Text] / C. J. Farrugia [et al.] // SOLAR-TERRESTRIAL RELATIONS: PREDICTING THE EFFECTS ON THE NEAR- EARTH ENVIRONMENT. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON PRESS LTD, 1998. - Vol. 22: DO 7 Symposium of COSPAR Scientific-Commission-D on Solar-Terrestrial Relations - Predicting the Effects on the Near-Earth Environment at the 31st COSPAR Sci Assembly (JUL 14-21, 1996, BIRMINGHAM, ENGLAND), Is. 1. - P67-72, DOI 10.1016/S0273-1177(97)01102-2. - Cited References: 19 . - ISBN 0273-1177. - ISBN 0-08-043465-7РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We compare numerical results of a steady-state MHD model for solar wind flow past the terrestrial magnetosphere with documented observations made by the AMPTE/IRM spacecraft on 24 October, 1985, during an inbound crossing of the magnetosheath. Observations indicate that steady conditions prevail during this similar to 4 hour-long crossing. The magnetic shear at entry into the magnetosphere was 15 deg. A steady density decrease and a concomitant magnetic field pile-up were observed during the similar to 40 min interval just preceding the magnetopause crossing. In this so-called plasma depletion layer (i) the plasma beta fell generally below unity; (ii) the flow speed tangential to the magnetopause was enhanced; and (iii) the local magnetic field and velocity vectors became increasingly more orthogonal to each other as the magnetopause was approached (Phan et al., 1994). We model parameter variations along a orbit similar to the AMPTE/IRM trajectory, which was at slightly southerly latitudes and similar to 1.5 hours post-noon local time (GSE). In our model we consider the magnetopause to be a tangential discontinuity, as suggested by the observations, and take as input solar wind parameters those measured by AMPTE/IRM just prior to its bow shock crossing. We find that theoretical predictions match all observations closely. (C) 1998 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Farrugia, C.J.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kistler, L.M.

[Text] : статья / A. N. Gorban, G. S. Yablonskii // Chemical Engineering Science. - 2011. - Vol. 66, Iss. 21. - p. 5388-5399DOI 10.1016/j.ces.2011.07.054 . -
Аннотация: The principle of detailed balance states that in equilibrium each elementary process is equilibrated by its reverse process. For many real physico-chemical complex systems (e.g. homogeneous combustion, heterogeneous catalytic oxidation, most enzyme reactions, etc.), detailed mechanisms include both reversible and irreversible reactions. In this case, the principle of detailed balance cannot be applied directly. We represent irreversible reactions as limits of reversible steps and obtain the principle of detailed balance for complex mechanisms with some irreversible elementary processes. We prove two consequences of the detailed balance for these mechanisms: the structural condition and the algebraic condition that form together the extended form of detailed balance. The algebraic condition is the principle of detailed balance for the reversible part. The structural condition is the convex hull of the stoichiometric vectors of the irreversible reactions has empty intersection with the linear span of the stoichiometric vectors of the reversible reactions. Physically, this means that the irreversible reactions cannot be included in oriented cyclic pathways. The systems with the extended form of detailed balance are also the limits of the reversible systems with detailed balance when some of the equilibrium concentrations (or activities) tend to zero. Surprisingly, the structure of the limit reaction mechanism crucially depends on the relative speeds of this tendency to zero.

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Доп.точки доступа:
Yablonskii, G.S.; Горбань, Александр Николаевич

[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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Держатели документа:
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]

/ L. I. Shkutin, N. A. Feodorova // Modelling, simulation & control. B. - 1995. - Vol. 58, Is. 3-4. - P11-20 . - ISSN 0761-2516
Аннотация: The double approximation of a displacement field in relation to the transversal coordinate is applied in constructing the two-dimensional model of a shell finite deformation. One of them, linear, is used in calculating the tangential derivatives of displacement field, the other, quadratic, is for the transversal derivative. In result, the displacement field gradient is approximated by the linear function of the transversal coordinate and the Green-Lagrange strain tensor is done by the quadratic one. The two-dimensional model of a shell finite deformation, accordant with the double approximation, contains three unknown vectors as internal kinematical variables of a shell base surface. Only two of them, coefficients of the linear approximation, are factors of the kinematical boundary conditions. They are primary vectorial parameters of the model and give six scalar degrees of shell freedom. The double approximation model of a shell finite deformation can be interpreted as the six-parametrical one with complete strain tensor. The model can be recommended for numerical analysis of shells, heterogeneous through thickness and laminated specifically.

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Держатели документа:
Computing Cent of the Siberian, Branch of the Russian Acad of, Sciences, Krasnoyarsk, Russian Federation
ИВМ СО РАН

Доп.точки доступа:
Shkutin, L.I.; Шкутин, Леонид Иванович; Feodorova, N.A.

/ S. P. Shary // Mathematics and Computers in Simulation. - 1995. - Vol. 39, Is. 1-2. - P53-85 . - ISSN 0378-4754
Аннотация: For the interval linear system Ax = b, the linear tolerance problem is considered that requires inner evaluation of the tolerable solution set ???(A, b) = {x ? Rn {divides} (?A ? A)(Ax ? b)} formed by all point vectors x such that the product Ax remains within b for all possible A ? A. Along with the simple incompatibility criterion, we develop comprehensive solvability theory for the linear tolerance problem that not only settles whether ??? is empty or not, but also enables modification of the problem to ensure its desired properties. To conclude, we advance several numerical methods of various accuracy and complexity for construction of an interval solution to the linear tolerance problem around a given center. В© 1995.

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Держатели документа:
Computer Center, Siberian Department, Russian Academy of Sciences, Akademgorodok, 660036 Krasnoyarsk, Russian Federation
ИВМ СО РАН

Доп.точки доступа:
Shary, S.P.; Шарый С.П.

[Текст] : статья / И. В. Киреев // Вычислительные технологии. - 2015. - Т. 20, № 2. - С. 44-55 . - ISSN 1560-7534
   Перевод заглавия: Inexpensive stopping criteria in the conjugate gradient method
Аннотация: Обсуждаются некоторые аспекты численной реализации метода сопряженных градиентов для решения систем линейных алгебраических уравнений с симметричной положительно определенной матрицей при наличии ошибок округления. Рассмотрены как пошаговое поведение некоторых широко распространенных версий алгоритма, так и критерии останова итерационного процесса.
In the paper, some aspects of the numerical implementation of the conjugate gradient method (CGM) for systems of linear algebraic equations with symmetric positive definite matrix in the presence of round-off errors are discussed. With exact calculations, CGM provides an exact solution in a finite number of iteration steps. But in fact CGM is an iterative process and the weak point in an iterative process is in a stopping criterion. It is required to determine the number of the iteration step, after which the accuracy of an approximation to a solution of a system of linear equations may not be considerably improved with a particular computer. Hence, the construction of inexpensive stopping criteria for CGM being the aim of this paper is an urgent problem. For four popular versions of CGM, the step-by-step behavior as well as stopping criteria for an iterative process are considered. Numerical results show that the most accurate approximation is achieved by the CGM-version where descent directions and residual vectors are orthogonal in the energy and Euclidean metrics, respectively, at each iteration step. A practical stopping criteria for CGM is proposed as a formula that enables one to determine the number of the CGM iteration step, starting with which the progress is no longer being made. The application of the constructed criteria to the solution of specific systems of linear algebraic equations with ill-conditioned matrices is demonstrated.

РИНЦ

Держатели документа:
Институт вычислительного моделирования СО РАН

Доп.точки доступа:
Kireev I.V.

/ B. G. Tarasov, V. M. Sadovskii // AIP Conference Proceedings. - 2016. - Vol. 1773: 8th International Conference for Promoting the Application of Mathematics in Technical and Natural Sciences, AMiTaNS 2016 (22 June 2016 through 27 June 2016, ) Conference code: 124420, DOI 10.1063/1.4964990 . -
Аннотация: Mathematical model of the equilibrium fan-structure formation between two elastic half-planes is constructed, simulating a shear rupture at stress conditions of seismogenic depths. The stress-strain state far from the fan-structure is analyzed with the help of solution of the problem on the Volterra edge dislocation resulted in estimation of the fan length. The model of formation of two differently directed fans due to the localized action of tangential stress, which pushes two edge dislocations with the antiparallel Burgers vectors, is proposed and analysed. © 2016 Author(s).

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Держатели документа:
University of Western Australia, Stirling Highway 35, Perth, WA, Australia
Institute of Computational Modeling, SB RAS, Akademgorodok 50/44, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Tarasov, B. G.; Sadovskii, V. M.

/ B. G. Tarasov [et al.] // Appl. Math. Model. - 2018. - Vol. 57. - P268-279, DOI 10.1016/j.apm.2018.01.020 . - ISSN 0307-904X
Аннотация: The mathematical model of an equilibrium fan-structure in the interface between two elastic blocks, simulating the shear rupture head in a hard rock under high confining pressure, is constructed. The stress–strain state far from the fan-structure is analyzed with the help of a solution of the problem on edge dislocation. The fan length is estimated using this solution. The model of formation of two oppositely directed fans due to the localized action of tangential stress, which pushes two edge dislocations with antiparallel Burgers vectors, is proposed. In complete formulation, the problem on an equilibrium fan-structure in the interface between infinite elastic half-planes is analyzed by means of original method of superposition of dislocations, leading to two nonlinear integral equations in the fan zone. To solve them numerically, the method of successive approximations is applied. Based on this method, fields of stresses and displacements around the equilibrium fan modelling of a deep-seated shear rupture in the seismogenic zone of the Earth's crust are computed. Such fields can be used, when setting the initial data in the analysis of dynamics of the fan-shaped mechanism. © 2018 Elsevier Inc.

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Держатели документа:
Centre for Offshore Foundation Systems, University of Western Australia, Perth, WA, Australia
Institute of Computational Modelling SB RAS, Krasnoyarsk, Russian Federation

Доп.точки доступа:
Tarasov, B. G.; Sadovskii, V. M.; Sadovskaya, O. V.; Cassidy, M. J.; Randolph, M. F.

[Текст] / В. М. Садовский [и др.]. - [Б. м. : б. и.], 1998. - Б. ц.
Перевод заглавия: Development of numerical methods for the solution of contact elastic-plastic problems
   Перевод заглавия: Development of numerical methods for the solution of contact elastic-plastic problems
Аннотация: При помощи формулировки граничных условий контактного взаимодействия деформируемых тел с учетом трения Кулона в виде квазивариационного неравенства разработаны оригинальные алгоритмы численного решения динамических контактных задач, обладающие вычислительной устойчивостью и гарантирующие выполнение геометрических ограничений в заранее неизвестной зоне контакта, условия неотрицательности нормального давления и противоположную направленность векторов касательной скорости и касательного напряжения при проскальзывании. Построены и обоснованы новые разностные схемы решения одномерных и двумерных задач динамики слоисто-неоднородных упругих и упругопластических сред, преимущества которых перед известными схемами выражаются в высокой точности описания разрывов, монотонности, отсутствии иных нефизичных эффектов. Разработан математический аппарат для исследования точности приближенных решений задач динамики упругопластических тел на основе алгоритмов корректировки решения.
Original methods are worked out for numerical analysis of a dynamic contact interaction between deformable bodies taking account of Kulon's friction by means of the formulation of suitable boundary conditions in the form of quasi-variational inequalities. The application of this formulation makes possible to construct iterative procedures, having computational stability and guaranteeing the implementation of geometric constraints in a priori unknown, changing in process of deformation contact zone, and also conditions of nonnegativity of the normal pressure, opposite directedness of tangent velocity and tangent stress vectors for slipping. New finite difference schemes are constructed for the solution of one-dimensional and two-dimensional problems of dynamics of laminated inhomogeneous elastic and elastoplastic media. Such properties as multiple precision of discontinuous solutions description, monotonicity and absence of other nonphysical effects are related to advantages of these schemes. Mathematical approach is suggested for analysis of precision of approximate solutions of dynamic problems by means of special algorithms of solution correction.

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Держатели документа:
Институт вычислительного моделирования СО РАН (ИВМ СО РАН)

Доп.точки доступа:
Садовский, В.М.; Sadovskii V.M.; Бычек, О.В.; Sadovskaya O.V.; Блинов, А.Н.; Богульский, И.О.
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