Open Repository of Keldysh Institute of Applied Mathematics of RAS
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The formal apparatus of simulation and interpretation antagonistic conflicts on the base of an electronic polygon
No full textAbstract:
The formal apparatus of simulation and interpretation antagonistic conflicts on the basis of the software complex of the electronic polygon is discussed. Features of application of computing technology of urgent computing in the supercomputer environment of interpretation of conflict situations are considered. The main attention is paid to the use of computational structures of the polymodel complex integrating intelligent technologies of urgent computing in the problems of formation and development of various forms of conflict situations in conditions of significant uncertainty (neoconflictology).Note:
Research direction:Mathematical modelling in actual problems of science and technic
Acceleration of iterations when solving the particle transport equation by extrapolating the source by iteration index
No full textAbstract:
The rate of convergence of the iterative algorithm for solving the transport equation of particles (neutrons or photons) is investigated. The iteration acceleration algorithm is based on nonlinear extrapolation of the source of scattered particles by the iteration index. A series of test problems was solved. It was found that the acceleration coefficient increases with increasing the problem degeneration (i.e., with increasing the ratio of the conservative scattering cross section of particles to the total cross section) and reaches a value of ten. The combination of the method with the Seidel method additionally increases the acceleration coefficient by one and a half to two times. The advantages of the method are simplicity of implementation, a small number of arithmetic operations and a small amount of stored information during the iteration. The method is comparable to the method of simple iterations on these parameters.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Simulation of radiative heat transfer in moving plasmas, taking into account the Doppler shift of lines
No full textAbstract:
The method of averaging the radiation transfer equation over the photon energy, which takes into account the resonant structure of the cross sections and emission spectra, as well as the directional Doppler shift of the lines due to the plasma motion, is presented. The method uses the similarity of spectra at points characterized by equal absorption. Combining points into one calculated point greatly reduces the number of arithmetic operations when performing numerical calculations of radiation transfer. The influence of the Doppler shift of lines on the processes of radiative heat transfer in solving model problems was estimated.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Submarine transport vessels for the transit corridor Southeast Asia – Europe in the Arctic Ocean
No full textAbstract:
The use of the Arctic Ocean as a year-round transport corridor from Southeast Asia to Western Europe can provide economic advantages for Russia, comparable to the exploitation of canals between the oceans – the Suez and Panama. Economically efficient year-round navigation along the northern transport corridor is possible with an underwater delivery of goods scheme. To reduce the cost of the project, it is proposed to build transport submarine from fiber and armature concrete, much more cheap and technological materials in comparison to steel. Load-unloading is proposed to be made in lighters, and loading of lighters into underwater transport ships is carried out before the ice border. Opening heavy (more than 10,000 tons) hatches for lighters loading is possible in the transport ship underwater position, when the weight of the hatches is compensated by Archimedes' force. The paper presents a system analysis of the project, its economic background, as well as the simple mathematical models needed to demonstrate the effectiveness of the submarine transport fleet.Note:
Research direction:Theoretical and applied problems of mechanic
«Luna-Glob» spacecraft attitude motion control in the mode of the constant solar orientation
No full textAbstract:
The preprint deals with the development of the attitude motion algorithms for Luna-Glob spacecraft (SC) to construct and maintain a constant solar orientation mode (CSO) during the Earth-Moon flight. The main requirement for CSO mode is to put SC in position relative to the Sun which provides the best illumination of solar panels for maximum electricity flow onboard.
Control algorithms and programs are developed, which allow conducting the statistical analysis for evaluation of algorithms performance at different initial SC orientation relative to the Sun and different initial angular velocity.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Development and application of numerical methods for solving tasks in unlimited regions based on the third Green formula
No full textAbstract:
The two-step algorithm for solving problems with a linear elliptic operator, for which the fundamental solution is known, is analyzed. New methods for solving problems in an unbounded areas with a mixed type operator are proposed: a method for expanding a domain, a method for specifying of integral boundary conditions and a three-step iterative method. The range of applicability of the constructed methods is limited by cases where outside a certain finite area the operators have a known fundamental solution and their right-hand side is homogeneous. To solve specific problems on the basis of the proposed methods, computational algorithms have been created, implemented in the form of computer software. A series of computational experiments confirming the correctness of the methods carried out. The results of calculations of the electromagnetic field around the rails of an electrodynamic rail-type accelerator in the two-dimensional case are presented.Note:
Research direction:Mathematical modelling in actual problems of science and technic
An algorithm of the explicit type to solve problems of non-isothermal multiphase flows in porous media
No full textAbstract:
A mathematical model of non-isothermal filtration of slightly compressible fluid built by the analogy with quasigasdynamic system of equations as well as an algorithm of the explicit type for its numerical implementation are considered in the paper. Verification is performed by the test problem of two-phase fluid (water-air) infiltration due to the gravity: a good agreement of numerical results with given in the literature results of other authors has been obtained. To investigate an influence of thermal effects on the filtration dynamics computations of three-phase fluid (water-oil-air) flow in a porous medium with a hot water source on the boundary have been fulfilled.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Methods for calculating the gravitational potential of a homogeneous triaxial ellipsoid and their application to the analysis of asteroid’s satellite dynamics
No full textAbstract:
For the study of the asteroid’s satellite dynamics, the problem of calculating the exterior gravitational potential and the attraction of an asteroid approximated by a homogeneous triaxial ellipsoid is considered. Three algorithms for calculating the gravitational potential of an ellipsoid are constructed. It is, firstly, an algorithm for approximate determination of the potential using its usual expansion in a series of spherical functions with harmonics up to 4th order inclusive. The other two ones determine the potential using the Dirichlet formula containing elliptic integrals. One calculates these integrals numerically by quadrature formulas. Another, analytical one uses the expansions of integrals developed in the work into rapidly convergent series. The application of these algorithms to calculate the potential and the attraction force of the asteroid Apophis is consideredNote:
Research direction:Theoretical and applied problems of mechanic
Space nonuniform electron kinetic equation solution by finite difference method in quasi neutral regime
No full textAbstract:
Algorithm for the numerical solution of the Vlasov-Landau kinetic equation in 1D2V geometry is
suggested. The nonlinear collision operator is computed on the base of the completely conservative difference scheme. Self consistent electrical field is computed from the condition of quasi neutrality
at each time step. The numerical results for the initial temperature profile relaxation in the semi-space are presented.Note:
Research direction:Mathematical modelling in actual problems of science and technic
General approach to solving the inverse problem of kinematics for a manipulator of a sequential structure by means of a finite rotation and displacement
No full textAbstract:
A new approach to solving the inverse problem of kinematics for manipulators of a sequential structure with an arbitrary number of links connected by kinematic pairs of the fifth class is developed. Theorems on the finite angle of rotation and displacement for each degree of mobility of the manipulator are formulated, which make it possible to optimally use each degree of mobility when the gripper moves to specified position and orientation parameters when solving the inverse kinematics problem.Note:
Research direction:Theoretical and applied problems of mechanic