Absorption of microwave energy by composites based on magnetic colloids
Absorption of microwave energy by composites based on magnetic colloids
S. A. Bozhenko$^1$, S. D. Turkin$^2$, A. R. Zakinyan$^2$, L. M. Kulgina$^2$
The absorption and reflection spectra of composites synthesized on the basis of magnetic liquids with the addition of conductive nonmagnetic particles under the influence of a constant magnetic field have been experimentally studied. The measurements were carried out on the main TEM mode of a coaxial waveguide in the frequency range of 10-18 GHz. To interpret the results obtained, numerical modeling of the system under study was carried out in the approximation of an effective medium using the finite element method.
Show AbstractSpace-like pion off-shell form factors in the Bethe-Salpeter approach
Space-like pion off-shell form factors in the Bethe-Salpeter approach
S. G. Bondarenko$^{1,2}$, M. K. Slautin$^{1,2}$
In the paper, the off-shell electromagnetic pion form factors in the Bethe-Salpeter formalism are considered. The separable kernel of the first rank quark-antiquark interaction is used to solve the equation analytically.The semi-off-shell pion form factors 𝐹1 and 𝐹2, which are related to each other by the Ward-Takahashi identity, are calculated. The obtained off-shell form factors as well as static properties of the pion are compared with the results of other authors
Show AbstractRare decay D→ωl+l
Rare decay D→ωl+l
V. .. Galkin$^1$, I. .. Sukhanov$^{1,2}$
Rare decays of charmed mesons due to flavour-changing weak neutral currents are forbidden at the tree level in the Standard Model and are additionally suppressed by the Glashow-Iliopoulos-Maiani mechanism. As a result, the role of intermediate resonance contributions increases significantly. Rare decays of $D$ meson into light vector meson $\omega$ are studied in detail within the framework of the relativistic quark model based on the quasipotential approach and quantum chromodynamics. The effects of electroweak physics at short distances and the contributions of intermediate resonances at large distances are taken into account using effective Wilson coefficients. The obtained results are consistent with the existing upper experimental limits.
Show AbstractInvestigation of the characteristics of rolled scale with magnetic properties to determine its effectiveness as an adsorbent
Investigation of the characteristics of rolled scale with magnetic properties to determine its effectiveness as an adsorbent
S. A. Kotov, Z. V. Naumova, T. S. Kudryavtseva, V. V. Davydov, O. I. Suchkova
One of the tasks of applied physics is to develop new methods for the use of condensed media, which are waste from various industries. In this case, several problems are solved, both related to ecology in its various applications, and to the production of various elements using physico-chemical processes. The paper considers rolling scale, which is formed in large quantities during the operation of metallurgical enterprises. One of the possible options for recycling rolled scale (recycling) is related to the possibility of its use as a sorbent in liquid purification and filtration systems. Morphological, chemical, and phase features of rolled scale are considered to determine its potential for sorption activity. Using spectral studies, a comparative analysis of magnetic and non-magnetic fractions was carried out, and differences in the content of iron-containing phases and impurity elements were revealed. It is established that the microstructure and composition of the material are determined by the conditions of its formation and directly affect the adsorption characteristics. The presence of magnetite and a porous structure contributes to the formation of an active surface for the deposition of chemically active elements on it, such as phosphorus, zinc and other dangerous elements that are not removed by mechanical filtration.
Show AbstractОпределение характеристик пластиковых сцинтилляционных детекторов
Определение характеристик пластиковых сцинтилляционных детекторов
P. G. Filonchik$^{1,2}$, D. N. Grozdanov$^{2,3}$, Yu. N. Kopach$^2$, P. S. Prusachenko$^2$, N. A. Fedorov$^2$, I. N. Ruskov
В Объединённом институте ядерных исследований (ОИЯИ) в Лаборатории нейтронной физики им. Франка (ЛНФ) в группе TANGRA проводится эксперимент по исследованию угловых корреляций в реакции неупругого рассеяния нейтронов с энергией 14,1 МэВ на ядрах углерода. Для регистрации нейтронов использовались 10 длинных (1 метр) пластиковых сцинтилляционных детекторов производства компании EPIC CRYSTAL. Их особенностью является наличие двух фотоэлектронных умножителей (ФЭУ), благодаря чему они обладают позиционной чувствительностью. В настоящей работе были выполнены измерения характеристик этих детекторов: пространственное разрешение и коэффициент затухания.
Show AbstractThe effect of the addition of neptunium on the duration of the fuel campaign in the BN reactor
The effect of the addition of neptunium on the duration of the fuel campaign in the BN reactor
V. A. Pavlovich, M. A. Kharkov, V. O. Skulkin
The aim of the work is to evaluate the possibility of using neptunium as fuel for the BN-600 reactor and its subsequent effect on the length of the fuel campaign. To carry out the calculations, neutron physics and thermophysical models of fuel assemblies of reactors were created. Neptunium was added to the main fuel homogeneously in various proportions ranging from 1 to 20% in the form of NpO2 oxide. The characteristics under consideration are the neutron multiplication coefficient in an infinite medium, and the spatial temperature distribution in the fuel element. The homogeneous addition of neptunium to the fuel has a negative effect on Keff. Adding a fraction of neptunium oxide of more than 5% is impractical. The addition of neptunium also had a negative effect on the energy release values, but to a lesser extent. When neptunium is added, the temperature of the BN-600 fuel rods changes by 2-3% at the fuel assembly inlet and outlet.
Show AbstractThe method of "Large particles" in mathematical modeling of Kelvin–Helmholtz instability in air
The method of "Large particles" in mathematical modeling of Kelvin–Helmholtz instability in air
S. I. Kosyakov$^{1,2}$, S. N. Kulichkov$^{1,2}$, M. N. Zakirov$^1$
The application of the well–known "Large particles" method in mathematical modeling of the simplest type of shear flows - a two-dimensional unsteady plane mixing layer is considered. The results of direct numerical simulation of the Kelvin-Helmholtz instability development at the interface of two layers of air of different densities moving with a tangential velocity shift in a field of strong external acceleration are described. The reliability of the calculation results is confirmed by comparing them with analytical calculations, with the results of numerical solution of a similar problem, as well as with experimental data. Based on the results of calculations, a new functional dependence of the increase in the width of the mixing layer on time, external acceleration, the difference in the densities of the air layers and the velocity difference at the contact boundary is obtained. This dependence is obtained for large values of acceleration values, velocity differences, and density at the gap. It will be useful for predicting the expansion of mixing zones in various currents with a tangential velocity gap, which are ubiquitous both in technology and in the atmosphere – for example, at the initial section of the jet, at the initial stage of mixing in a cylindrical vortex, with the development of wavy clouds or instability of a clear sky in the atmosphere.
Show AbstractOn the development of Kelvin-Helmholtz instability in the front region of an intense nonlinear acoustic wave in the atmosphere
On the development of Kelvin-Helmholtz instability in the front region of an intense nonlinear acoustic wave in the atmosphere
S. I. Kosyakov$^{1,2}$, S. N. Kulichkov$^{1,2}$, M. Z. Nafisovich$^1$
Currently, a significant effect of the expansion of the front region of intense nonlinear acoustic waves created in the atmosphere by pulsed point sources of various nature has not been fully explained – the recorded width of the front region is several orders of magnitude larger than it follows from theoretical concepts. To explain such a significant effect, a hypothesis has been put forward about the possibility of developing Kelvin-Helmholtz instability inside the front region of the wave with a shear flow caused by a mass velocity gradient in the front region itself. The paper substantiates the proposed hypothesis. For this purpose, direct (without using any semi-empirical models) numerical simulation of the Kelvin-Helmholtz instability inside a physically infinitesimal volume of air in the front region of an intense nonlinear acoustic wave is performed. The homogeneous plane motion of compressed air in a wave is considered. It is shown for the first time that the development of Kelvin-Helmholtz instability at different distances from the source should have geometric similarity due to the fact that the process develops in an ideal environment. It does not matter whether the width of the front area increases as the wave moves away from the source or it increases due to an increase in its energy.
Show AbstractEstimation of Curium effect on neutron-physical characteristics of BN and VVER reactors under the homogeneous distribution
Estimation of Curium effect on neutron-physical characteristics of BN and VVER reactors under the homogeneous distribution
V. V. Hramkov, D. R. Aliev, V. O. Skulkin, A. A. Vorontsova, E. A. Gerdt, P. M. Aleksandrovich
The research aim is investigation of the curium affection on neutron-physical and thermophysical characteristics of VVER-1200 and BN-600. The fuel assemblies neutron-physical and thermophysical models have been created for the calculations to be made. Curium was added to the common fuel homogeneously in the proportions from 0,1 to 20 % as CmO2 oxide. Characteristics considered are: neutron multiplication factor, neutron spectrum, temperature distribution. A stronger effect on the reactivity is observed of the VVER-1200 model – Keff decreases by 3,85%. The maximum decrease of BN-600 neutron multiplication factor is 3%. Adding curium increases the neutron flux density of VVER-1200. Also curium does a considerable positive effect on the fast reactor’s reactivity, that creates a possibility of using Cm as a fuel. The maximum fuel temperature decreases by 500 grad, when curium is added.
Show AbstractNumerical modeling of vapor-liquid equilibria of ternary mixtures of hydrocarbons and carbon dioxide
Numerical modeling of vapor-liquid equilibria of ternary mixtures of hydrocarbons and carbon dioxide
D. V. Selezneva
In the oil and gas industry, carbon dioxide injection into the reservoir is considered a promising method for enhancing oil recovery: when dissolved in hydrocarbons, the viscosity of oil decreases and a swelling process occurs, which improves the efficiency of displacement. At certain values of pressure and temperature, a three-phase equilibrium can form in the system - two liquid phases (enriched in carbon dioxide and enriched in hydrocarbons) and a gas phase, which seriously complicates the use of classical iterative algorithms for calculating phase equilibria with stability tests. In this paper, the method of direct minimization of the Gibbs free energy at fixed values of pressure and temperature was used to determine the boundaries of the regions of two-phase and three-phase equilibrium; in addition, the viscosities of each phase were calculated using the Lorenz-Bray-Clark model, which made it possible to quantitatively estimate the decrease in the viscosity of the oil phase.
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