Vol 74, No 5 (2019)

This article presents the results of a series of fundamental studies on a new type of a surface microwave discharge conducted at the Department of Physics of Moscow State University. The discharge is created by a surface wave on a dielectric antenna when powerful electromagnetic radiation in the centimeter wavelength range is supplied to it. The basic properties of a microwave discharge and the spatiotemporal evolution of the parameters of plasma generated by a surface discharge are investigated in a wide range of changes in external conditions.

The role of natural selection in biological evolution, which reflects contemporary biological concepts, is described systematically. A new approach based on the ideas regarding the physical phenomenon of percolation is suggested and developed to generalize the theoretical and mathematical description of this key problem of biology. The natural selection of optimal variants in the evolutionary mutation flow is considered as a percolation filter, a physical tool constituting the selection mechanism. The model is based on the concept of self-organization in hierarchical speciation structures, where trigger properties of a cell (node) as a valve define the deterministic component of fixing new mutations, and the drift defines the collective behavior of the percolation lattice nodes and connections (mutations) that introduces an element of randomness to the process of fixing new mutations in mutation flows. As a result of considering various values of the selection and drift coefficients, as well as the ratio of prohibiting and permitting mutations, the modes of fixing mutations in generations were obtained at the population level.

This work is devoted to the theoretical study of the magnetoplastic effect that manifests itself in the motion of dislocations in solids in the presence of a magnetic field without mechanical loading. An expression is obtained for the effective magnetic charge per unit length of dislocation, which occurs due to the action of the magnetic field on the dislocation. The effects associated with the induced magnetic charges at dislocations are studied. It is shown that the effective magnetic charge occurs due to the interaction between the magnetic field and only the edge components of dislocations. An expression for the force that acts on a dislocation in the magnetic field is derived and it is shown that in experiments on studying the motion of dislocations in the presence of magnetic fields the projection of this force onto the dislocation glide plane must play a dominant role.

This article studies the behavior of the electronic levels of a hydrogen atom in a space bounded by a flat surface on which a condition of the spatial confinement of electronic wave functions is specified. It is shown that a significant amount of energy can be released during adsorption of hydrogen atoms by a sample with a clean smooth surface, high affinity, and low initial internal hydrogen concentration. The results are obtained using both direct numerical calculation using the finite element method and variational estimates based on the selection of special test functions.

The phenomenological modeling of nonlinear harmonic generation in single-pass free electron laser (FEL) experiments was performed. The gradual saturation of the harmonic power and its evolution around the saturated regime was modeled. The model includes all major losses for each harmonic with account for the fact that the undulator radiation (UR) and the electron-wave interaction at higher harmonic wavelengths are more sensitive to the beam energy spread, divergence, and other factors. The results of the phenomenological modeling are compared with the experimental data of the corresponding FELs and with the numerical simulation. The proposed description of nonlinear harmonic generation appears to be in good agreement with the FEL experiments SALCA, LEUTL, LCLS, and others under various conditions. The results also match their numerical simulations; in contrast to the latter, our phenomenological model allows rapid, still, and accurate modeling of the FEL harmonic power and bunching evolution with a PC or even an engineering calculator. The model permits studying FEL radiation from undulators with arbitrary magnetic field configuration. Using the analytical FEL model, we demonstrate that, in contrast to the helical undulator, in whose spectrum the fundamental and the second harmonics prevail, the FEL radiation from the elliptical undulator with the third field harmonic has a distinct fifth UR harmonic as well as the fundamental one, whereas other harmonics can be ignored even close to the saturation length.

Quantum-dot cellular automata (QCA) is a new computing paradigm based on cellular automata with appealing characteristics such as high speed, low power consumption, and high density for realizing quantum computers. On the other hand, an adder is the primary circuit in any digital processor and ripple carry adder is a basic building block of other adders. Therefore, efficient design of this type of adder may lead to the efficient design of the whole system. So, in this paper, a new design of ripple carry adder is proposed to decrease the number of cells and area as possible. Simulation results using QCA Designer verifies the correctness of the proposed circuit and validates its efficiency in terms of a number of cells and area.

The experimental results of measurement of the scalar and vector characteristics of an acoustic field in shallow water with a carbon bottom are analyzed. Simultaneous recording of the sound pressure and three orthogonal components of particle velocity was carried out using a sound pressure receiver and a vector receiver. A towed transducer was the source of the tone signal; the noise signal from a passing ship was a source located near the water—air boundary. In the spatial decay of the sound field components, significant variations in the levels of sound pressure and particle velocity components were observed, regardless of the depth of the sound source. When the sound source was located in the depth of the water layer, the dependence of the spatial decrease in the acoustic field components is diverse, while when the noise signal source was located below the water—air interface, the decay character of the sound pressure amplitudes and of the vertical component of the particle velocity were the same throughout the measurement path.

In the present work, tungsten composites were mechanically alloyed for 6 h and sintered at 1750°C under N₂, H₂ gas flowing conditions. Phase and microstructural characterization investigations of tungsten alloys were carried out using X-ray diffraction, scanning electron microscopy, small-angle neutron scattering, and Raman spectroscopy. Tungsten boron and tungsten boride as major phases were determined in the X-ray diffraction patterns. Raman spectra indicated the existence of the carbon phases, which are the disordered graphite (D) and graphite (C). Small-angle neutron scattering measurements were performed to obtain the distribution of powders. The results were in good agreement with scanning electron microscopy findings.

The development of a pulsed volume discharge with pre-ionization in a non-uniform supersonic air flow near the wedge in the shock tube channel and the gas-dynamic flow that occur after the discharge has been experimentally studied. Plasma configurations that occur near the bottom of the wedge were investigated for the discharge initiated at various stages of an unsteady flow. The self-localization conditions of a volume discharge in the vortex zone behind the wedge are analyzed at the incident shock wave Mach numbers of 2.6–3.5 (at the flow Mach numbers up to 1.50 and a density up to0.15 kg/m³).

The present work seeks to calculate and development of a new set of the personal dose equivalent conversion coefficients (Skins Dose) for mono-energetic photons (in absorbed dose and Kerma approximations), electrons and positrons from 10 keV to 10 MeV on the phantom ICRU tissue. The conversion coefficients calculations were two ways: Monte Carlo and development an analytical approach using FORTRAN program. The results obtained in this work were found to be in good agreement with to those published in joint report of ICRU and ICRP, 2017 [1]. The numerical comparison was made to validate DOSRZnrc code for conversion coefficients calculations as well as testing the developed of an analytical a new approach using FORTRAN. Our study can be useful to improve standards of protection for medical workers for procedure resulting in potentially high exposures and to develop methodologies for the best assessing and for reducing exposures.

A part of the celestial sphere which has a cosmic string candidate (CSc-1 field) according to the radio data on cosmic microwave background anisotropy is statistically investigated to further substantiate this candidate. Cosmic strings are 1D cosmological-scale objects that can manifest themselves in particular as gravitational lenses with characteristic features. The problem of statistical comparison of the density distribution of gravitational-lens pairs of sources (galaxies) in the fields without cosmic strings with the distribution of similar pairs in the CSc-1 field is solved. Nonparametric rank tests are used to handle small samples under an unknown distribution law. The limits of applicability of the test are discussed. The revealed difference between the two distributions serves as an additional argument in favor of the presence of a string in the CSc-1 field. The discovery of cosmic strings would serve as a unique observational test of modern cosmological theories, including multidimensional models.

This paper investigates the applicability of the DRAGON5 and DONJON5 code system to develop an accurate full-core model of the Moroccan 2 MW TRIGA Mark-II research reactor. The evaluated cross-section data library ENDFB.VII.1 with SHEM-295 group structure was used. A validation approach is applied to verify the consistency of the developed model. The results of the deterministic calculations based on ENDFB.VII.1/DRAGON5/DONJON5 scheme are compared with the experimental values available in the safety analysis report (SAR) as well as the Monte Carlo results. It was found that the DRAGON5 and DONJON5 code system results for core excess reactivity, critical size, reactivity worth of the five control rods, the power distribution and hot rod power peaking factor are in good agreement with measurements and the MCNP5 simulation values. Therefore, this study proves the capability of the DRAGON5 and DONJON5 code system to reliably simulate the TRIGA Type research reactors.