Methods for extracting nucleon resonance parameters from experimental data are reviewed. The formalism for the description of exclusive reactions of meson photo- and electroproduction off nucleons is discussed. Recent experimental data on exclusive meson production in the scattering of electrons and photons off protons are analyzed.
Show AbstractThis paper considers one of the problematic issues of creating radio systems based on cognitive radio technology, viz., automatic recognition of the digital-modulation formats of radio signals. In accordance with the recommendations of the E2R and the European Telecommunications Standards Institute (ETSI) consortium, cognitive radio systems have the ability to modulate/demodulate signals in all frequency bands and in all modes of modulation. This process should be performed automatically, according to the current technical capabilities of the available communication system, the requirements for the quality of communication, and different external conditions. This article provides an analysis of the promising methods of automatic recognition of digitally modulated radio signal formats, viz., using the shape of the phase constellation, using the distribution difference of instantaneous phases, and using high-order cumulants. According to the results of the analysis, we propose methods of recognition that are based on cumulant analysis for cognitive radio systems. It is proposed that the decision-making device be an artificial neural network.
Show AbstractIonizing radiation is widely used in medicine today. Sources of ionizing radiation include X-ray tubes, natural and artificial isotopes, and accelerators [1, 2]. This review describes the role of accelerator technology and nuclear physics methods in cancer treatment. It presents an analysis of the data that have been published in scientific articles and reports, materials of the IAEA, and other places over the course of the past 5 decades.
Show AbstractThe phase structure of a (2+1)-dimensional Gross–Neveu model with four different channels of fermion–antifermion interaction, and, correspondingly, four different coupling constants, is studied. It is shown that the model describes five different phases of the interaction of planar fermions in which either spatial parity or chiral symmetry can be broken. The existence of a phase that is characterized by simultaneous spontaneous breaking of both these symmetries that was not observed earlier in such models is demonstrated.
Show AbstractA mathematical model of a mirror collimator with rounded edges is developed. The problem of calculating electromagnetic field components in the target area is solved by the method of integral equations. The results of numerical computations are presented.
Show AbstractA new algorithm for object identification by their images is proposed. It combines tolerance against imaging conditions variations proper to morphological methods for image analysis by Pyt’yev with computational simplicity of methods based on separating classes of images with hyperplane. The algorithm was tested on images taken in different illuminations and views. It can be applied to analyse microscopic image in biophysics, acoustic signals in geophysics, Earth resources using satellite data, etc.
Show AbstractThe equation for an energy gap is investigated using the fluctuation theory of high-temperature superconductivity. It is shown that the proposed mechanism can explain an increase in critical temperature, Tc. An explicit expression for the critical temperature is obtained using the technique of rectangular pits.
Show AbstractA numerical two-dimensional hydrodynamic model was used to describe the influence of forest belts of different sizes on turbulent transport of SO$_2$ within the atmospheric surface layer. The results of the model calculations showed that the presence of a forest belt results in an substantial reduction of the horizontal SO$_2$ flux due to the decrease of the wind speed and the absorption of SO$_2$ by tree crowns. The extinction coefficient of SO$_2$ flux increases with an increase in the forest belt size and decrease with the pollution source height.
Show AbstractThe reconstruction efficiency of photons and neutral pions is measured using the relative yields of reconstructed $B^{+}\to J/\psi K^{*+}(\to K^+\pi^0 )$ and $B^{+}\to J/\psi K^+$ decays. The efficiency is studied using the data set, corresponding to an integrated luminosity of $3 \mathrm{fb}^{-1}$, collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV.
Show AbstractThe capabilities of dynamics analysis of the sounding-beam intensity profile at the output of an atmospheric path on the basis of the chronogram structure tensor are considered. The spatio–temporal structure of the velocity field of refraction distortions is investigated. The characteristic dimensions of the regions of the translational and rotational types of flow motions are determined. The profiles of local velocity projections are obtained, as well as their statistical properties under the conditions of weak variations of meteoparameters in the output flow recording interval. Comparison of the characteristic values of wind velocity that is recorded with an array of anemometers and those calculated with the suggested method allowed us to elaborate an approach to the rough estimation of the translational and fluctuation components of aerodynamic flows at the path.
Show AbstractThe results of Х-ray research on the structural characteristics of the Pd$_3$Ni alloy after its electrolytic saturation by hydrogen during relaxation are presented. The synchronous changes in the period of a lattice and the value of elastic stresses, which started immidiately after sample hydrogenation and continued for 500 hours of relaxation, were found for the first time. The observed changes are caused by the cooperative processes of the displacements of vacancies and nickel atoms between defect complexes and an alloy matrix.
Show AbstractIn this work we compare two force fields that are intended for the molecular dynamics simulation of the process of the deposition of silicon dioxide thin films. Analysis of the structural characteristics (the density and radial distribution function) of a glassy silicon dioxide cluster that was used as a substrate and a deposited film is carried out. It is shown that the DESIL force field in which the Van der Waals interaction is described by the Lennard–Jones potential turns out to be more suitable for modeling the process of deposition
Show AbstractThe results from studying a dual-camera inductive radio-frequency (RF) discharge that was placed in an external magnetic field are presented. The operating conditions were as follows: an argon pressure of 5 × 10$^{–5}$–6 × 10$^{–2}$ Torr, an external magnetic field strength of 0–60 G, and an RF generator power supply of 25–300 W. During the experiment the resonant RF power consumption and the correspondence between the local power-consumption maxima and spatial maxima of the plasma concentration as a function of the external magnetic field were observed. The comparison of the experimental results with the results of the mathematical simulation indicates that the resonant character of the discharge is associated with the excitation of helicons and Trivelpiece–Gould waves.
Show AbstractThe results of structural hydrophysical investigations at the Pleshcheyevo Lake are presented. There were at first revealed on the base of the data of direct measurements the distributions of parameters of current velocity and of water composition in lake. The theoretical distribution of current velocity with taken in to account the influence of internal wave, circulation and intrusion was verified. The submerged jet of the river water inflow in lake was discovered. There were obtained the measured and theoretical distributions of the total solids in jet. The quality corresponding between the obtained results and the materials of publications on the influence of currents on the biosphere of lake was established.
Show AbstractThe generation of acoustic-gravity waves and their propagation in the Earth’s atmosphere is analyzed numerically on the basis of a computer model of the stratified atmosphere with dissipation. Atmospheric and ionospheric wavelike disturbances from different surface sources such as earthquakes, explosions, seiches, temperature heating, and tsunamis are studied.
Show AbstractIn light of the planned space missions to the Moon and Mars to study the inner structures of these celestial bodies by seismic methods, theoretical studies of possible peculiarities of the inner structures of these celestial bodies are particularly relevant. Our previous investigations showed that the mechanism of forced oscillations of the core and mantle of a celestial body under the gravitational influence of other celestial bodies may play a key role. Moreover, it allows a number of planetary processes and phenomena on the Earth and the other planets to be explained. Specifically, this mechanism gives us an opportunity to reveal geodesic changes and to study the nature and origin of some of the inner formations of the Earth, the Moon, and Mars. In the present paper, we explain the presence of a zone of lower seismic velocities (LVZ) on the Earth at a mean depth of approximately 145 km and predict the analogous LVZ on Mars at a depth of approximately 300 km.
Show AbstractThe toroidal (orthogonal) decomposition of the vector potential of the magnetic fields is proposed. Based on this decomposition we have developed electrodynamics equations of permanent and variable electromagnetic fields. Applications of the developed electrodynamics to natural phenomena and laboratory experiments are discussed.
Show AbstractDredged samples of basalts from the Mid-Atlantic Ridge (MAR) and the Red Sea Rift that are 0.2 to 1 Ma in age are used to show the possibility of separating the thermoremanent and chemical remanent magnetization components in oceanic basalts by the conventional Thellier–Coe method. It is found that the decay rate of chemical remanent magnetization during exposure of basalt samples with Curie temperatures of $T_{c}=145$ and 240$^{\circ}$C at temperatures of 340–380$^{\circ}$C in the air was less than the formation of partial thermoremanent magnetization during the experiments using the Thellier–Coe method by a factor of 4.5–5; in contrast, for thermoremanent magnetization these rates almost coincide. Using this fact, we estimated the contributions from chemical remanent and thermoremanent magnetization components into the natural magnetization of basalts and, based on the thermoremanent magnetization component, defined the paleointensity of the geomagnetic field for the epoch when these basalts formed. In basalts from the southern MAR that are 1 Ma in age, the contribution of chemical remanent magnetization to the natural remanent magnetization is 60% to 80%; in those of 0.35 Ma it was less than 50%; in those of 0.2 Ma it was less than 10%. The calculated values of the virtual magnetic dipole moment of the Earth were close to those that have been published in the literature.
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