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2008Korshunov, A., Kaganova, I., Polyakov, L., Kravchenko, T. Effects of equal - channel angular pressing on the anisotropy of ultrafine copper and titanium // Materials Science Forum, 2008, 584 - 586 PART 1, Pages 487 - 492 RFNC - VNIIEF, Sarov, Russian Federation Annealed commercially pure copper and titanium were processed by equal - channel angular pressing ( ECAP ) using routes BC and C. Pressed samples had a square section with a side length of 8 mm. Anisotropy was analyzed based on the conventional yield strength at compression in three mutually perpendicular directions. The tests were conducted with the as - received materials and after different number of ECAP passes. For copper, which is isotropic in the as - received state, considerable anisotropy manifests itself after the first pass and holds out after the subsequent passes. Anisotropy of as - received titanium holds out at further pressing and makes about 25 percent. Anisotropy after all the passes is similar both for room and elevated temperature. Anisotropy manifests itself during pressing in both routes, B C and C, although its behavior differs for the different routes. Yarovikov, V.I., Zaitsev, L.Ya., Smirnov, V.D. Portable vibrator for combined testing of instruments and sensors // Measurement Techniques, 2008, Volume 51, Issue 4, Pages 406 - 411 RFNC - VNIIEF, Sarov, Russian Federation A small vibrator for combined testing of instruments and sensors is developed on the basis of an inverse piezoelectric effect. The vibrator is a resonant converter with fluctuations in bending that includes a dismountable support bracket for fastening an instrument under test and a built - in piezoaccelerometer for automatic vibration control. Ustinenko, V.a , Samigulin, Ma., Ioilev, A.a, Lo, S.b, Tentner, A.c , Lychagin, A.d, Razin, A.d, Girin, V.d, Vanyukov, Ye.d Validation of CFD - BWR, a new two - phase computational fluid dynamics model for boiling water reactor analysis // Nuclear Engineering and Design, 2008, Volume 238, Issue 3, Pages 660 - 670 a RFNC - VNIIEF, Sarov, Russian Federation To allow the detailed analysis of the two - phase coolant flow and heat transfer phenomena in a boiling water reactor fuel bundle the CFD - BWR model is being developed for use with the commercial code STAR - CD which provides general two - phase flow modeling capabilities. The paper reviews the key boiling phenomenological models, describes the overall strategy adopted for the combined CFD - BWR and STAR - CD boiling models validation and presents results of a set of experiment analyses focused on the validation of specific models implemented in the code. The location of vapor generation onset, axial temperature profile and axial and radial void distributions were calculated and compared with experimental data. Good agreement between computed and measured results was obtained for a large number of test cases. Arinin, V.A. Histogram analysis and synthesis in processing series of images: Extending the concept of image similarity // Pattern Recognition and Image Analysis, 2008, Volume 18, Issue 4, Pages 588 - 591 RFNC - VNIIEF, Sarov, Russian Federation Specific elementwise operations over images based on analyzing and synthesizing histograms are described. An image is seen as part of an essentially two - dimensional continuous function given on a discrete grid and normalized to an interval of [ 0; 1 ]. Images with degenerate histograms, i.e., images that include big continuous sections or a small number of quantization levels, are not considered. A histogram is a distribution of the image function, which is discrete in our case, with its sum ( or area ) normalized to 1. Such normalization makes operations invariant with respect to pixel size of the image and allows, with no loss of generality, changing sizes of the sampling grid ( resampling ) and adding uniformly distributed noise for ill - conditioned histograms. Kudasov, Yu.B.a,b , Korshunov, A.S.a, Pavlov, V.N.a, Maslov, D.A.b Dynamics of magnetization in frustrated spin - chain system Ca3Co2O6 // Physical Review B - Condensed Matter and Materials Physics, 2008, Volume 78, Issue 13, art. no. 132407 The magnetization dynamics of the triangular lattice of Ising spin chains is investigated in the framework of a two - dimensional model. The rigid chains are assumed to interact with the nearest - neighboring chains, an external magnetic field, and a heat reservoir that causes the chains to change their states randomly with time. A probability of a single spin - flip process is assumed in a Glauber - type form. This technique allows describing properly the steps in the magnetization curves observed in Ca3Co2O6 and their dependence on a magnetic - field sweep rate and temperature. A formation of domain walls due to the nonequilibrium magnetization process and a significant role of their motion are shown. Borissenok, V.A. Sonoluminescence: Two sources of light // Physics Letters, Section A: General, Atomic and Solid State Physics, 2008, Volume 372, Issue 19, Pages 3496 - 3500 RFNC - VNIIEF, Sarov, Russian Federation The model of sonoluminescence with two sources of light is presented. The first of them is gas inside the bubble heated during collapse. The second source ( main ) is plasma in the breakdown channel in liquid. Solontsov, A.a,b, Mirmelstein, A.c Spin fluctuation driven structural phase transitions in itinerant electron magnets: γ → α transition in Ce - based compounds // Physics Letters, Section A: General, Atomic and Solid State Physics, 2008, Volume 372, Issue 12, Pages 2086 - 2090 a State Center for Condensed Matter Physics, Rogova street 5a, 123060, Moscow, Russian Federation We suggest a novel mechanism of structural transitions in itinerant electron magnets, driven by spin fluctuations strongly coupled to the crystal lattice. The mechanism explains the isostructural γ → α transition in Ce - based compounds. The high - temperature γ - phase is shown to be stabilized by spin fluctuations dominating the bulk modulus. With the decrease of temperature and spin fluctuation amplitudes the bulk modulus becomes negative giving rise to a structural instability. The structural phase transition to the low - temperature α - phase is accompanied by the change of the volume described in terms of the order parameter defined by the volume strain. Semenova, I.P.a, Korshunov, A.I.b, Salimgareeva, G.Kh.a, Latysh, V.V.a, Yakushina, E.B.a, Valiev, R.Z.a Mechanical behavior of ultrafine - grained titanium rods obtained using severe plastic deformation // Physics of Metals and Metallography, 2008, Volume 106, Issue 2, Pages 211 - 218 a Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, ul. K. Marksa 12, Ufa, 450000 Bashkortostan, Russian Federation We present the results of the investigation of the mechanical behavior of ultrafine - grained ( UFG ) titanium rods - semifinished products obtained by equal - channel angular ( ECA ) pressing in combination with subsequent thermomechanical treatment. This material shows ultimately high values of strength ( 1240 MPa ) and plasticity ( relative elongation 12.5% ) at room temperature. At the same time, at elevated temperatures the UFG titanium exhibits signs of superplastic behavior with large relative elongations and an enhanced strain - rate sensitivity to the flow stress. The greatest elongation at fracture equal to approximately 300% was reached at 500°C and a strain rate of 10 -4 s -1. The microstructure and microhardness of the samples after superplastic deformation have been investigated. It has been established that superplastic treatment can favor " structural improvement " of the UFG titanium and further enhancement in its strength. Babich, L.P., Dudin, V.I., Ivanovskii, A.V., Kutsyk, I.M., Morozov, I.V., Tokarev, V.A., Shaidullin, V.Sh. Influence of the Hall effect on the plasma dynamics in an MTF/MAGO chamber // Plasma Physics Reports, 2008, Volume 34, Issue 5, Pages 355 - 365 RFNC - VNIIEF, Sarov, Russian Federation The role of the Hall effect in experiments on the magnetic implosion of a D - T plasma in a cylindrical MTF / MAGO chamber fed from a helical explosive magnetic generator is investigated. The plasma dynamics is simulated numerically by a 2D code developed for solving the set of MHD equations with account of the Hall effect. In simulations, the generator, the break switch, and other units were replaced with LR circuits. It is shown that taking into account the Hall effect provides better agreement between numerical simulations and experimental data. Pikulev, A.A., Tsvetkov, V.M., Sosnin, P.V., Sinyanskii, A.A. Nuclear - pumped laser operating in the master oscillator - Amplifier regime // Quantum Electronics, 2008, Volume 38, Issue 7, Pages 655 - 660 RFNC - VNIIEF, Sarov, Russian Federation The efficiency of a master oscillator - amplifier scheme and the possibility of its using in multichannel nuclear - pumped laser systems are studied. The small - signal gain and saturation parameter are measured for the He : Ar : Xe = 380 : 380 : 1 mixture at a pressure of 1 atm at a wavelength of 2,03 µm. It is shown that the small - signal gain increases linearly with the specific pump power density and achieves 1,1 - 1,2 m -1 at a pump density of 40 W cm -3. The saturation parameter is almost independent of the pump power and is equal to 70 - 90 W cm -2. It is found that at the pump-pulse maximum ( 40 W cm -3 ) the laser radiation power increases after amplification by 100%.
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