Open Repository of Keldysh Institute of Applied Mathematics of RAS
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TEFIS database. Thermodynamic functions of substances
No full textAbstract:
The TEFIS database includes data on thermo physical properties of substances under extreme conditions (high temperatures and enormous range of densities). It is based on original physical models which have been developed in M.V. Keldysh Institute of Applied Mathematics since 1960's. The first part of the database includes tables of thermodynamic functions for all elements of the periodic system. They are constructed via only two models: the generalized Saha model and the Tomas-Fermi model with quantum and exchange corrections. In this work, we briefly discuss the models, present their verification and describe the tables uploaded at the Institute server.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Structure of semantic connections of words of the Russian explanatory dictionary
No full textAbstract:
In this paper the result of statistical analysis of connections between words of the Russian explanatory dictionary is presented. It is found that the dictionary graph contains a strongly connected component, through which the explanation of the meaning of words is ultimately carried out. This graph also contains a self-similar shell of the kernel, so-called channel, and the periphery in which, along with the kernel connections, internal cycles are exist in a small fraction. The structure of the core links is studied and the main clusters are identified, with the help of which it is proposed to carry out semantic analysis of the text.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Influence of synchrotron and photorecombination radiation on nonlinear absorption of Alfven wave by dissipative plasma
No full textAbstract:
A mathematical model of the Alfven wave absorption is proposed, the study of which is based on the equations of two-fluid electromagnetic hydrodynamics with electron inertia and bremsstrahlung taking into account. Special attention is paid to the research of the additional effects of photorecombination and synchrotron radiation. The investigation revealed, in particular, the finite depth of the Alfven wave penetration into the plasma. Another important effect is the establishment of the parameters of the absorbed Alfven wave and their convergence to the quasi-stationary regime.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Processing of semantic queries in the Protégé environment on the example of the ontology of road signs construction
No full textAbstract:
This paper is devoted to considering the possibility of applying the approach of semantic description and ontology as input data for the algorithm and tool for recognizing traffic signs and helping the driver in driving. The paper presents a model of the semantic description of road signs and the traffic situation based on Protégé software. The advantages and disadvantages of the model are described. The possibility of using the model on the on-board computer of the vehicle is considered. A comparative analysis of tools for solving semantic problems and time of decision making is given.Note:
Research direction:Programming, parallel computing, multimedi
A new look at projecting of visual representation for applied mathematical computation
No full textAbstract:
Perspective concept of a previously designed web browser visual editor is described. Initially the editor intended to be only a component of a large system for specialized applied mathematical computation. Now, arguments for autonomous development of this component are suggested. The target application area for the editor is decision support systems.Note:
Research direction:Programming, parallel computing, multimedi
Methods for study the flow of complex structure
No full textAbstract:
Methods for studying and describing the flow of complex structure is demonstratеd. Approaches based on spectral methods, on the theory of dynamic systems and on the computational homology methods are considered. All methods were applied to analyze a multiscale convection in a horizontal fluid layer with the temperature dependence of thermal diffusivity. It is shown that full description of the flow of complex structure can be obtained from a combination of different methods and approaches of the flow study.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Differential equations for the radial limits in Z+2of the solutions of a discrete integrable system
No full textAbstract:
A limiting property of the coefficients of the nearest-neighbor recurrence coefficients for the multiple orthogonal polynomials is studying. Namely, assuming existence of the limits along rays of the lattice nearest-neighbor coefficients, we describe the limit in terms of the solution of a system of ordinary differential equations. For Angelesco systems, the result is illustrated numerically.Note:
Research direction:Mathematical problems and theory of numerical method
Asymptotical basis of solutions of q-recurrence relations outside of the zone of clustering eigenvalues
No full textAbstract:
A procedure for constructing expansions of the basis of solutions of a four-term recurrence relations with coefficitnts from the ring Z[q,1/q] is described. The
fact that outside of the zone of the clustering eigenvalues these expansions are the asymptotical expansions is proven.Note:
Research direction:Mathematical problems and theory of numerical method
SIR distribution for dynamical system trajectories on the example of underground tube
No full textAbstract:
In this work the properties of the distribution functions of the reliability functional of wireless communication between transmitting and receiving devices are studied, when the motion of these devices is given in the form of a dynamic system. As practical examples, transport systems of the metro of the cities of St. Petersburg, Moscow and London are considered. The minimum sufficient time intervals at which the sample distribution functions of the signal-to-interference ratio become stationary are numerically determined.Note:
Research direction:Mathematical modelling in actual problems of science and technic
Family of symmetric bicompact schemes with spectral resolution property for hyperbolic equations
No full textAbstract:
For the numerical solution of nonstationary quasilinear hyperbolic equations, a family of symmetric semidiscrete bicompact schemes based on collocation polynomials is constructed in the one- and multidimensional cases. A dispersion analysis of semidiscrete bicompact schemes of fourth to eighth orders of accuracy in space is performed. Numerical examples are presented that demonstrate the ability of the bicompact schemes to adequately simulate wave propagation, including short waves, on highly nonuniform grids at long times. The properties of solutions of the bicompact schemes in the problem of transfer of a stepwise initial profile are also considered.Note:
Research direction:Mathematical problems and theory of numerical methodsRussia