Open Repository of Keldysh Institute of Applied Mathematics of RAS
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A compression method for a topology of tetrahedral meshes
No full textAbstract:
This paper contains the description of sequential two-step tetrahedral mesh topology compression method and its software implementation. The results of compression of ten meshes containing up to 134•106elements are presented.Note:
Research direction:Programming, parallel computing, multimedi
Using the library aiwlib on the example of numerical modeling of stochastic resonance
No full textAbstract:
Aiwlib library is a library for C++11 and Python languages, which is aimed for the development of high-performance computing numerical simulation applications running under GNU/Linux OS. It also provides means for batch calculations, search through results using multiparametric filters and visualization of results. In the last ten years, the library has been successfully used to create high-end software and carry out calculations in various fields.
In this paper we show in detail the application of aiwlib in the study of stochastic resonance in a system with nonlinear Brownian motion. For the numerical solution of the Fokker-Planck equation, the stochastic analog method is used. This paper describes the creation of the code, the launch of calculations and the analysis of the results.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Investigation of convective structures near the stability threshold in non-Boussinesq fluid. Part one – analysis of simple models
No full textAbstract:
The paper investigates stable convective structures in vertically asymmetric horizontal fluid layer. The asymmetry is caused by internal heat generation, variable thermal diffusion and variable kinematic viscosity (temperature and vertical coordinate dependence is considered). The first part of the paper provides analysis of Prandtl number effect on the planform selection in scope of amplitude equations and perturbation method. The second part of the paper deals with a comparison of theoretical data to results of 3D numerical simulation of convective instability in finite layer of non-Boussinesq fluid.Note:
Research direction:Mathematical modelling in actual problems of science and technic
On the commutation of quantum operators of the first integrals of Hamiltonian systems
No full textAbstract:
In this paper the effect of integrability destruction is analyzed for Hamiltonian system with complete set of the first integrals under linear quantization. The operators, corresponding to these integrals, are investigated. The example of integrable two-dimensional dynamical system is considered. The perturbation of quantum operators is analyzed for the case of integrability conservation.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Nonlinear travelling waves in hot plas
No full textAbstract:
Planar traveling waves in a hot magnetized plasma are found and classified in the case of a zero transverse electric field (in the reference frame of the background motion of the plasma). The obtained results are used to estimate the prospects of using the quasi-steady plasma accelerator with a longitudinal magnetic field for accelerating plasma in the channels of plasma accelerators.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Albedo of the planet as an indicator of the evolution of the Earth's climate (The 65th anniversary of the Keldysh Institute of Applied Mathematics and the achievements of the 'Lunar Program' is dedicated)
No full textAbstract:
The purpose of this publication is to draw attention to a class of large problems of aerospace remote sensing and global monitoring of the Earth's climate as a planet, for which solutions require parallel supercomputers and high - performance supercomputers. A spherical model of the Earth's radiation field is proposed to simulate the spectral and global albedo of the planet and a bit of history.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Statistical model of space objects distribution in space of orbital parameters
No full textAbstract:
A statistical model of space debris is proposed. The model is based on the catalog of orbits of space objects, constructed using domestic and foreign sources. To build this model, the cataloged objects are clustering using criterion of closeness in a 4d space of orbital parameters characterizing the semimajor axis, eccentricity and position of the plane of the satellite orbits composing a cluster. The distribution of objects in each cluster is determined by the mathematical expectation and the covariance matrix of the spread of the orbital parameters of the cluster.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Rigidity of the Hamburger and Stieltjes moment sequences
No full textAbstract:
This paper aims at finding conditions on a Hamburger or Stieltjes moment sequence, under which the change of at most a finite number of its entries produces another sequence of the same type. It turns out that a moment sequence allows all small enough variations of this kind precisely when it is indeterminate. We also show that a determinate moment sequence has the finite index of determinacy if and only if the corresponding finite number of its entries can be changed in a certain way.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Water body crossing by a six-legged robot on a raft with a cargo
No full textAbstract:
Motion of the robot is formed with the aim the crossing with a cargo from one side onto the other side of the water body in the simplest case, when the robot initially pushes the raft from the shore. The proposed control algorithm provides for the transfer of a cargo from a shore to the raft, transporting cargo on a moving raft and transfer of the cargo from the raft to the other shore. The algorithm was worked out by means of computer simulation.
The results of calculations show the performance of the algorithm in the presence of motion information, adequate for management purposesNote:
Research direction:Theoretical and applied problems of mechanic
High-order accurate schemes and their application for the direct numerical simulation of bora in Novorossiysk
No full textAbstract:
In this paper, the method of calculating of arbitrary spatial derivatives with any predefined approximation order was studied; its properties and limitations are defined. This method was used to construct an explicit high-order accurate finite-difference Lax-Wendroff-type scheme for solving the system of gas dynamics equations. The obtained scheme was applied to simulation of the extreme wind bora in Novorossiysk. The comparison of the numerical results with the averaged data of meteorological observations showed that the proposed model corresponds to the real atmospheric flow.Note:
Research direction:Mathematical modelling in actual problems of science and technic