ISSUES OF ATOMIC SCIENCE AND TECHNOLOGY
Series: Mathematical simulation of physical processes
| Year | 2011 | 2010 | 2009 | |
| Issue | 1-2-3-4 | 1-2-3-4 | 1-2-3-4 | |
2009
ISSUE 4
ABSTRACTS:
UDK 519.6
SOLVING HEAT TRANSFER EQUATIONS ON UNSTRUCTURED DIRICHLET GRIDS USING AN EFFICIENT SCHEME / I. D. Sofronov, A. I. Panov, A. V. Samodolov // P. 3
An efficient difference scheme for solving multidimensional heat transfer equations on unstructured Dirichlet grids is described. The scheme was proposed and substantiated by
I. D. Sofronov. A specific feature of this scheme is that it can be used on highly heterogeneous grids of cells with a variable number of vertices. The scheme can be used to solve both linear and quasi-linear heat transfer equations in 2D and 3D cases.
Key words: unstructured Dirichlet grids, split scheme, numerical solution of 2D and 3D heat conduction problems.
UDK 519.6
CODE SOLYARIS FOR NUMERICAL SIMULATION OF RADIATION TRANSPORT IN MULTIDIMENSIONAL STRUCTURES WITH VACUUM SPACES WITH REGARD TO GAS DYNAMIC MOTION AND OTHER PHYSICAL PROCESSES ON MULTIPROCESSORS / O. A. Abramova, A. A. Bazin, G. V. Dolgoleva, T. V. Korol'kova, S. N. Krupina, V. M. Mel'nikov, V. F. Mironova, E. A. Novikova, P. I. Pevnaya, E. I. Ryabov, I. N. Salova, B. P. Tikhomirov, Yu. A. Tsibereva, R. M. Shagaliev, B. N. Shamraev // P.12
The paper describes code SOLYARIS for 1D numerical simulation on multiprocessor of the radiation transport in complex-geometry multidimensional structures with optically dense and optically transparent regions with regard to gas dynamic motion and spectral radiation transport in a material in quasi-diffusion approximation.
The paper presents physico-mathematical models and describes the main ideas of the technique allowing simulation of physical processes of various kinds, as well as the main algorithms implemented and approaches to parallelization, and also gives results of efficient parallelization.
Key words: numerical simulation, spectral radiation transport in vacuum, heat conduction, quasi-diffusion approximation, one-dimensional approximation, gas dynamics, spectral diffusion, nonequilibrium diffusion, visibility factor, thermonuclear combustion kinetics, laser energy absorption and transport, explosive decomposition and combustion kinetics, polymeric coating swelling, melting, parallel computations.
UDK 533.6.011.72
GENERALIZED DIFFERENTIAL RELATIONS ON A SHOCK / A. L. Adrianov // P. 22
The paper describes the derivation of generalized differential relations on a curvilinear shock in non-uniform flow of a viscous heat-conductive ideal gas. ''Viscous'' terms have been taken into account with approximation to a shear layer of asymptotical order O (1). The system of symbolic transformations on a computer was used during the relation derivation process. Ultimately, the derived relations are written in the matrix form with a small parameter in the highest derivatives and nonlinear terms. Coefficients are not given for these relations because of their awkwardness. In a limit non-viscous case, the generalized differential relations identically coincide with the known results.
Key words: curvilinear shock, viscous heat-conductive ideal gas, shear layer, schematization of shock using gas-dynamic strong discontinuity surface, computer analytic symbolic conversion system, generalized differential relations (conditions) on a curvilinear shock, asymptotic approach, small parameter, extreme nonviscous case, edge effect, additional differential constraint, interaction vortex model, analytical solution.
UDK 519.6
CODE SNDMA FOR CALCULATION OF EMITTING NON-EQUILIBRIUM MOLECULAR PLASMA FLOWS / V. D. Atamanenko, G. V. Dolgoleva, V. A. Zhmailo, I. V. Popov // P. 31
The paper presents SNDMA code for the calculation of flows of emitting non-equilibrium molecular plasma jointly with the kinetics of chemical, photo-chemical, plasma-chemical, photo- and radiation-plasma-chemical reactions in air plasma.
The physical model and numerical solution techniques are described and the calculated results are compared with the analytical solutions to test problems.
Key words: calculation of emitting non-equilibrium molecular plasma flows, numerical solution technique.
UDK 621.039.586
SOLUTION OF THE HEAT CONDUCTION PROBLEM FOR A CYLINDER OF FINITE DIMENSIONS WITH INTERNAL HEAT SOURCES / M. V. Kashcheev // P. 45
The paper considers the problem of a cooling-down homogeneous cylindrical rod of a round cross-section and finite length located in the environment, which temperature varies with time. The heat exchange according to the Newton law is observed on the rod's boundaries. The time-ependent heat conduction problem in a finite-size cylinder has been solved using the method of finite integral transformations.
Key words: heat conduction problem, cylindrical rod, internal heat source, method of finite integral transformations, differential operator, characteristic equation, transformation core, boundary, environment.
UDK 519.6
TIME INSTABILITY MEASUREMENT TOOLS FOR MULTI- PROCESSORS / Yu. G. Bartenev, A. M. Vargin, V. A. Erzunov, V. V. Koshelev, D.V. Kulnev, D. I. Lipov, P. S. Lobanov, A. V. Lomtev, D. A. Novaev, A. N. Petrik, T. V. Semenova, G. P. Semenov, S. A. Firsov, E. B. Shchanikova // P. 49
The paper describes Noise Measurement Suite, which is a software package for measurements of noises in a parallel computer with a large number of processors impacting the job
parallelization efficiency. In literature, noise means random interferences during the process of computations, for example, owing to conflicts in a set of operating components, or asynchronous operations of the parallel computer's control system on various processors. The suite of tools allows estimating the impact of noises on the performance of parallel user applications on the given computer and assessing a possibility of scaling the given firmware platform to create a more powerful computer system with the required performance of the given parallel applications.
Key words: multi-processor computer, parallel application, process, operating system, programming language Python.
UDK 519.6
JOB BATCH PROCESSING SYSTEM JAM / A. B. Kiselev, S. N. Kiselev // C. 60
The job batch processing system JAM (system software JAM) described in the paper has been created to provide effective use of computing resources of the cluster with JAM. For this purpose, the algorithm of filling gaps (backfill algorithm), combinations of this algorithm with the worst-fit and best-fit algorithms and algorithms of allocating jobs to the cluster nodes with regard to the structure of interconnects of its high-performance communication network have been implemented.
The paper gives the general description of the system and the scheme of interconnections of its program components, in particular, interconnections between scheduler and node demons of
JAM implemented owing to the use of JINI technology and JavaSpace service. The system capabilities, which are absent in similar commercial software products, or products for free release, are described, namely:
- data transfer from output flow and job process diagnostics flow to the program server located on the control development computer;
- interaction between the server and executable components implemented using JINI technology with JavaSpace service;
- job allocation to the adjacent nodes connected to the adjacent switches of the high-performance communication network;
- adjustable mechanism of the job "pulse" monitoring that allows automatically finishing a hung-up job.
The job batch processing system JAM has been integrated with a united queue system (UQS) and in this combination it can be used for management of a heterogeneous computer complex at large Computation Center.
Key words: multi-processor computation system, batch job processing, batch job scheduling, program order reversal method (backfill).
UDK 519.6
THE ENVIRONMENT FOR INTERACTIVELY VIEWING SIMULATIONS ON SUPERCOMPUTERS / P. A. Vasyov // C. 67
An ability to interact with a running application may be very useful for the user to debug his parallel applications and reduce the numerical experiment duration. Such interaction implies monitoring of the parallel application state and a possibility to control its operation. However, standard technologies allowing such scenario implementation are not available at present time. So, it is of great interest to improve the modern computing systems in order to equip them with the function of interactively starting jobs.
Another useful feature of interactive mode is that it allows viewing remote data, i.e. viewing data not transmitted to the given user's computer. This makes it possible to reduce the waiting period between the completed computations and the result viewing start time and also save the network and disk resources.
The paper presents simple and easy to use software system implementing the above-mentioned interactive scenarios. The system is intended for monitoring and control of small- and middle-size jobs, allows viewing remote data using modern technologies for construction of the user interface and can be used both in local and global networks.
Key words: visualization, parallel computations, interface.
UDK 621.386.12/17
THE EFFECT OF "REPACKING" THE RADIATION BEAM PROJECTIONS FROM RADIAL TO PARALLEL GEOMETRY ON THE QUALITY OF TOMOGRAPHIC IMAGES / S. A. Lavrov, E. N. Simonov // P. 78
The paper considers the algorithms of reconstructing images using the inverse projecting method with filtering by folding for the radial and parallel scanning geometries. The algorithm of
repacking the radiation beam projections from radial to parallel geometries is presented.
The paper shows that the difference of images between the radial geometry and the parallel geometry after repacking has been performed becomes smaller (both for high-contrast and
low-contrast objects) with the increased number of view angles.
Key words: X-ray computed tomography, radial and parallel scanning geometries, image reconstruction, repacking.
| Year | 2011 | 2010 | 2009 | |
| Issue | 1-2-3-4 | 1-2-3-4 | 1-2-3-4 | |