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Vestnik NSU. Series: Physics. 2015. V10, i 4 |
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Radiophysics and Electronics |
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Kuznetsov S. A., Arzhannikov A. V. Electromagnetic Optimization of Ultra-Thin Resonant Absorbers for Bolometric Detectors of the Submillimeter-Wave Range We present the results of theoretical analysis and characteristics optimization for ultra-thin resonant absorbers based on artificial impedance surfaces, which are promising for using as the radiation sensitive layers in selective bolometric detectors operating in the range of submillimeter waves. The key parameters of the ultra-thin absorbers, such as the absorption resonance Q-factor, the ratio of the peak absorptivity wavelength to the absorber thickness and the impedance surface unit cell size, are traced versus a geometric shape of the resonant elements and their electrical conductivity. |
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Physics of Field, Neutral and Ionized Gases |
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Litvinenko Yu. A., Balbutsky A. B., Vikhorev V. V., Kozlov G. V., Litvinenko M. V. Experimental Study of the Development of Hydrodynamic Instability in Round Microjet under the Influence of External Acoustic Field with and without Burning Experimental study of subsonic round micro jets in the diffusion combustion of propane and
without combustion at low Reynolds numbers was performed. Development of the jet was as under
natural conditions without the acoustic excitation and as acoustic excitation of high intensity (90–
100 dB), frequency of acoustic oscillations was from a few Hz to 6 kHz. The jet flow was realized
through the nozzle of round cross-section with a bevel of 45° and a diameter d = 0,45 mm. Blown
trough the nozzle mixture of propane-butane previously passed through the evaporator, then through
flowmeter (two-channel PR4000B) gas consumption. The studies were performed using Schlieren |
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Boiko A. V. On Modelling the Stability of Fluid Flows in Compliant Pipes Applied to Hemodynamic Problems The study is directed to formulate physical models adequate to describe mechanisms of interactions of compliant walls of pipes and hydrodynamic disturbances aiming to reveal the conditions responsible for hydrodynamic instability in hemodynamic problems. |
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Arzhannikov A. V., Kotelnikov I. A. A Method of Solving a Non-Stationary Problem of Ship Waves Excitation by a Submerged Object We propose and develop a method of solving the problem of exciting ship waves by a submerged object that moves in a non-viscous fluid at a variable velocity. The case of the flush ball moving at constant velocity parallel to the surface of the liquid is considered to validate the proposed method by comparing the results with data reported earlier by other authors. Asymptotic expressions are derived describing the elevation of the liquid surface in the limit of small and large values of the Froude number. The exact solution is represented as two summands, each of them being reduced to one-dimensional integral. One summand describes the “Bernoulli hump”, and another - the “Kelvin wedge. |
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Grek G. R., Kozlov V. V., Korobeinichev O. P., Litvinenko Yu. A., Shmakov A. G. Features of the Diffusion Combustion of Hydrogen Microjet at Various Spatial Orientation of the Nozzle Exit The purpose of the given work will consist in the experimental studies of features diffusion
combustion of a hydrogen round microjet depending on spatial orientation of the nozzle exit. It is
revealed, that a hydrogen round microjet at diffusion combustion in conditions of a jet velocity vector
orientation towards terrestrial gravitation vector «g» (opposite or perpendicular) the basic characteristics
of the flame evolution depending on a jet velocity are practically coincided. To these
characteristics concern such as ranges of the «bottleneck» flame area presence, flame detachment at
presence of the «bottleneck» flame area, presence of the «bottleneck» flame area, but absence of a |
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Prokhorov E. S. Quasi-One-Dimentional Approach to Modeling of Propagation of Gas Detonation in a Medium with Variable Chemical Composition The quasi-one-dimensional model is presented to describe the propagation of detonation wave in a tube filled with an explosive gas mixture, the chemical composition of which varies along the tube axis. This takes into account energy losses chemical equilibrium flow of detonation products for friction and heat removal in the tube wall. Within the limits of this model, it numerically investigated the gas detonation transition through a region with the concentration gradient of chemical agents. It analyzed the possibility of excitation overdriven detonation waves as a result of this transition. |
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Yakovenko S. N. Budget of the Scalar Variance Equation in a Turbulent Patch Arising from Lee Wave Breaking Based on averaged data of the direct numerical simulations, statistical moments are obtained in a turbulent patch arising after lee wave overturning in a flow with stable stratification and obstacle. Temporal evolution and spatial behavior of the scalar-variance transport equation budget have been studied. A priori estimations of algebraic approximations for scalar dissipation, scalar variance and turbulent-diffusion processes in the scalar-variance equation have been carried out. Such an analysis is helpful to explore the turbulent patch in terms of statistical moments, and to verify closure hypotheses in turbulence models. In the global balance of the scalar-variance equation, the compensation of production by dissipation and advection is shown, as for the turbulent kinetic energy equation. The ratio of turbulent time scales of the scalar and velocity fields varies from 0.2 to 2.2 within the wave breaking region, and the global value of this parameter is close to unity during the quasisteady period. The algebraic expression derived from the assumption of production and dissipation balance is incorrect leading to unphysical negative values, therefore the use of the full scalarvariance equation in the turbulent transport model is justified. |
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Solid-State and Semiconductor Physics, Physics of Nanostructures |
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Pavlovskii N. S., Shaykhutdinov K. A., Dubrovskiy A. A., Petrov M. I., Terent’ev K. Yu., Semenov S. V. The Effect of Isovalent Substitution in the Rare-Earth Subsystem on Ground Magnetic State of a Single Crystal La1,4Sr1,6Mn2O7 In this report we investigate changing of magnetic properties of system (La1-zNdz)1.4Sr1.6Mn2O7 during isovalent substitution from lanthanium to neodymium at different concentration z = 0, 0.3. Decreasing of Mn-Mn in-plane distance with increasing z leads to the suppression of the ferromagnetic state that, as expected, tells us about the change of the orbital character eg – electrons with d3z2- r2 on the dx2- y2. Also, at high applied magnetic fields metamagnetic transition observed at concentration z = 0.3, it is characterized by a sharp increase of the magnetization and the change of the ground state of the sample from the antiferromagnetic to ferromagnetic. |
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Educational and Methodical Provision of Teaching of Physics |
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Popov L. K. On Nature of Osmosis Pressure In scientific and education literature you can find the opinion that osmosis is caused by the pressure of solved molecules. In this paper we present the critic of this conception and the valid physical interpretation of this phenomena. |
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