Vol 73, No 5 (2018)

An experiment to verify the adequacy of the Heisenberg uncertainty principle, as proposed by Karl Popper and implemented in practice, is considered. As in the Einstein–Podolsky–Rosen paradox, the quantum properties of an entangled pair of elementary particles are used. In this case, a ghost image of a narrow slit is actually formed. The results of the experiment, at first glance, support a violation of the uncertainty principle. However, analysis of the spatial resolution of the slit ghost image shows that this is not correct. A more correct description of diffraction in the case of spatially limited light beams, gives no violation of the uncertainty principle. The results can be also used to estimate the extreme quality of diffraction limited ghost images.

A nonlinear electrodynamic change in the phase of an electromagnetic wave after passing through a hexapole magnetic field is determined. It is shown that any pulse of electromagnetic radiation changes its initial polarization due to vacuum nonlinear electrodynamics equations. The front and back of the pulse with the length of cτ are linearly polarized in mutually orthogonal planes; the part enclosed between them, in the general case, becomes an elliptically polarized wave.

An algorithm for estimating the geometrical and phase corrections for receiving–transmitting transducers of a ring antenna array of an ultrasonic tomograph is proposed. These corrections should be taken into account at the stage of the reconstruction of the spatial distributions of the sound velocity and absorption coefficient of an object under study (the breast); otherwise, the quality of the obtained tomograms will deteriorate significantly.

We consider the problem of diffraction of a plane electromagnetic wave field at a linear cluster consisting of two plasmonic nanoparticles while accounting for the nonlocal effect. The research is based on the mathematical model of the generalized non-local optical response. On the basis of the modification of the discrete sources method, a comparative numerical analysis of the scattering characteristics in the frequency domain is carried out depending on the geometry of the particles and the distance between them. It has been established that taking longitudinal fields into account has a significant influence on the extinction cross section and even more on the scattering cross section.

Using density functional theory (DFT) calculations, we study the structural parameters and mechanic properties of Y₂Al compound. The independent elastic constants of Y₂Al compound were calculated and the results show that Y₂Al compound is mechanically stable. Some polycrystalline quantities such as the bulk and shear moduli, Young’s modulus, and Poisson’s ratio of Y₂Al compound were derived from calculated elastic constants. The obtained results were compared with the existing experimental and other theoretical data.

The method of parameterization of the electron energy spectrum of molecules is used to theoretically study the specific features of the energy spectrum of a family of molecules of the monometallic coordination compound of terpyridine with Rh, Ru, and Pt atoms and the electron transport properties of molecular single-atom transistors based on this family of molecules. The coefficients for the parametric shell model of the energy spectrum are obtained for the studied molecules. It is demonstrated that the electron-transport characteristics of molecular single-atom transistors with atoms of transition metals with similar numbers of d electrons have similar shapes and features.

The ionization degree of the plasma in a nonstationary pulsating discharge created by a stationary power source in subsonic and supersonic airflows has been determined. lt was experimentally found that the electron density in the plasma near electrodes varies from 10¹⁵ to 3.7 × 10¹⁶ cm^–3 and the gas temperature increases from 400 to 1250 K when the flow velocity varies from 150 to 520 m/s at a constant discharge current of 15.5 A. It is shown that the gas ionization degree in the pulsating discharge plasma is on the order of l0^–4 at low subsonic airflow velocities, while with the increase in the flow rate it increases sharply and reaches the value of 10^–2 at the velocity of 500 m/s.

It is shown that convective structures that form upon heating a planar liquid layer from below are determined not only by standard similarity parameters, such as the Prandtl, Rayleigh, and Marangoni numbers, but also by the presence or absence of an elastic film on the surface of the liquid, which occurs because of impurities and stabilizes the surface. The level of impurities contained in distilled water is enough to prevent Marangoni convection, and only additional purification (deionization) of water allows one to induce the thermocapillary effect. Using the method of infrared surface thermography, the mean size of thermal structures that emerge on the surface in different liquids at different temperatures and layer thicknesses is determined. A convection theory that takes the impurities in the linear and nonlinear approximations into account is examined and good compliance of the theoretical calculations with the experimental data obtained in the present work is demonstrated.

Material science is very important for developing the linear accelerator. Determination and understanding of material behavior face to X-rays is a basic study for photon beam modifiers improvements. In this study, the 6 MV photon beams produced by Varian Clinac 2100 was modelled by Monte Carlo simulation using BEAMnrc code and thereafter the flattening filter was replaced by a slab of aluminum and copper separately and by slab of both materials combined together with different thickness of 2.5, 5, 7.5, and 10 mm.

The purpose of this study is to investigate the scattered photons with thickness of combined material slab as a function of off-axis distance. The scattered photons increased with thickness of copper alone slab, combined aluminum-copper slab and copper-aluminum slab, but for aluminum alone slab they decreased with slab thickness. The stacking order of these two materials affects the characterization of scattered photons emergent from material slab with thickness. The combination of materials and the manner that the stacking was done affects the scattered photons production. The material combination could improve the radiotherapy efficiency in beam modifier development using more than two materials.

Motion modeling of two low-orbit linked satellites for measuring the Earth’s gravitational field parameters is presented. The model takes the factors that affect the satellite motion into account, such as nonspherical geopotential, atmospheric drag, tides, and third-body effects from the Moon, Sun, and planets of the Solar System. As a result of modeling, a search for the optimal configuration of satellites for completion of scientific tasks and possibility of technical realization is performed.

This paper deals with modification of a mathematical model for the multicomponent non-isothermal flow of oil and gas considering the processes of thermal degradation of kerogen upon heating of oil-kerogen-containing reservoirs. A system of differential equations that describe thermal degradation is formulated based on the data on testing a thermal-gas method at the deposit of the Bazhenov formation, as well as using the data from laboratory pyrolytic studies. The one-dimensional initial-boundary problem that is obtained is solved using numerical methods. The numerical experiments were carried out at different values of parameters for two models: the classical model of multi-component three-phase flow and the model supplemented by the equations that describe thermal degradation. The computational results obtained based on the two different models are compared; the advantages of the model proposed in this paper are shown.

This paper presents the results of numerical experiments on the impact of electromagnetic radiation on strength characteristics of natural and artificial materials and the data of laboratory experiments on the destruction of Berea sandstones and concretes under the impact of an electric current on loaded samples with a constant velocity of deformation.