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RUSSIAN FEDERAL NUCLEAR CENTER 
ALLRUSSIAN RESEARCH INSTITUTE OF EXPERIMENTAL PHYSICS 

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Issue N^{o} 3, 2014  LOGOS CODE PACKAGE. A FINITEELEMENT TECHNIQUE FOR THE STATIC STRENGTH PROBLEMS OF STRUCTURES WITH REGARD TO PHYSICAL AND GEOMETRICAL NONLINEARITY EFFECTS
O. L. Aleksandrova, R. A. Barabanov, D. Yu. D'yanov, S. S. Kosarim, A. O. Naumov, V. F. Spiridonov, E. A. Filimonkin, K. V. Tsiberev VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 317.
The paper considers the finiteelement technique implemented in LOGOS software to simulate the quasistatic strength problems of structures with regard to the effects of physical and geometrical nonlinearity. The technique implements the scheme of the finiteelement method in the form of the transport method, which is based on minimizing the potential energy functional of a strained system. For a linear elasticity case, the paper presents the basic relations and main finiteelement approximation formulas. The descriptions of algorithms generalizing the finiteelement technique to the case of nonlinear quasistatic strength problems of structures are presented. Key words: LOGOS code package, quasistatic strength, method of finite elements stressstrained state, physical nonlinearity, geometrical nonlinearity.
 SIMULATION OF TURBULENT FLOWS WITH HIGHERORDER SCHEMES ON HYBRIDSTRUCTURE GRIDS A. S. Kozelkov, R. N. Zhuchkov, A. A. Utkin, K. B. Volodchenkova VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 1831.
An approach to simulating unsteadystate separated turbulent flows for objects of complex geometries and the acoustic fields generated by such flows using grids of truncated hexahedrons is described and the approach implementation ideas are discussed. It is shown, by the example of problems on the simulation of a transonic unsteady turbulent flow in a cavern and the acoustic flows generated by it and the problem of a flow around a tandem of cylinders, that the algorithms in use seem promising for the given class of problems. Key words: a higher order accuracy, model of separated eddies, truncated hexahedrons, noise evaluation, LOGOS code package.
 STUDYING THE ACCURACY OF DIFFERENT METHODS OF AVERAGING THE HEAT CONDUCTIVITY COEFFICIENT ON AN INTEGRATION CELL SIDE DURING THE NUMERICAL SIMULATION OF THE HEAT TRANSFER EQUATION E. V. Avdoshina, Yu. A. Bondarenko, A. A. Gorbunov, Yu. S. Dmitrieva, A. O. Naumov, S. N. Pronevich, N. M. Rud'ko, B. P. Tikhomirov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 3246.
The way of averaging the heat conductivity coefficient on an integration cell side during the numerical simulation of the 2D and 3D heat transfer equations has a significant effect on the accuracy of simulations for nonlinear heat waves. To find an average value of the heat conductivity coefficient during the numerical simulation of the heat transfer equation, some codes use arithmetic, harmonic, halfharmonic, modified harmonic and some other averaging methods. The paper gives analytical assessment of the accuracy of different methods used for averaging the heat conductivity coefficient on an integration cell side. Simulation results are presented for two problems, for which exact solutions are available. It is demonstrated that the most accurate results have been obtained using some types of the modified harmonic method of averaging, where temperature on a cell side can be found by solving the nonlinear equation constructed with the requirement of continuity of the heat flux across the cell side. Key words: radiation heat transfer, heat conductivity coefficient, heattransfer resistance, the flow balance method, test simulations.
 FINITEDIFFERENCE SCHEME GROM FOR THE 2D QUASIDIFFUSIVE SYSTEM OF THERMAL RADIATION TRANSPORT EQUATIONS S. A. Grabovenskaya, V. V. Zavyalov, A. A. Shestakov VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 4758.
The paper considers a linear finitedifference scheme for the numerical simulation of the timedependent system of thermal radiation transport equations with the quasidiffusive method. The TVD type scheme is used to solve the transport equation. The nonlinear quasidiffusive equation system is solved with the VDM method. Results of numerical simulations for some test problems are presented. Key words: quasidiffusive method, radiation transport, finitedifference scheme.
 MONTE CARLO SIMULATION OF THE NEUTRON AND GAMMA TRANSPORT EQUATIONS ON COMPUTERS WITH ARITHMETIC ACCELERATORS I. V. Semenov, A. G. Mal'kin, A. S. Rybkin VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 5970.
The paper presents results of the development of SMKU code complex for solving the timeindependent neutron and gamma transport equation with the use of arithmetic accelerators. The main algorithmic modifications, as compared to SMK code, are described. Numerical investigations of the speedup have been performed for a number of nuclear power engineering problems. Key words: arithmetic accelerator, graphical processor, Monte Carlo method, parallelization in events, fuel element, fuel assembly, WWER1000.
 A METHOD FOR THE CHEMICAL COMPOSITION ANALYSIS IN MD SIMULATIONS WITH ReaxFF INTERACTION POTENTIAL O. V. Sergeyev, A. V. Yanilkin VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 7177.
The description of algorithm is given and the specific features of implementing the program for molecules on the base of the molecular dynamics simulation results are described. The simulation results dependence on the threshold value of bond order is discussed.en. Key words: molecular dynamics, ReaxFF, chemical composition.
 AN APPROACH TO AUTOMATICALLY CONSTRUCTING THE USER'S INTERFACE FOR SETTING PARAMETERS OF COMPUTATIONAL TECHNIQUES IN PREPOSTPROCESSOR LOGOSPREPOST A. A. Anishchenko, A. S. Santalov, V. N. Dyupin, V. I. Deryugin VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 7884.
An approach to automatically constructing the user's interface of prepostprocessor LOGOSPrepost is described. The implemented tools are intended and actively used for the user's interface development to set the initial and boundary conditions for the grid model in LOGOS code package. The paper describes some advantages of the developed user's interface: its flexibility, adjustability, and an ability of quickly and easily modifying the interface, if necessary. Key words: user's interface, standard dialog, tree of objects, business logics, LOGOSPrepost, models, parameters of computational techniques.
 SECURED FIBEROPTICS SYSTEMS FOR DISTRIBUTED COMPUTER NETWORKS S. N. Ivchenko, O. N. Naryshkina, S. I. Ovechkin, A. V. Svetikov, V. V. Shubin VANT. Ser.: Mat. Mod. Fiz. Proc. 2014. No 3. P. 8596.
The paper describes a number of secured fiberoptics systems known from open publications, which have been developed from the end of 1980's to present days and are used for data transmission in computer networks. Parameters, specific features, and the area of application of such data securing systems are given. The paper is focused on the modern software and hardware tools of FOBOS series providing data security, which have been developed at RFNCVNIIEF. Key words: data security system, secured fiberoptics datatransmission system, software and hardware tools providing data security.
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