This review considers the history and meaning of the phenomenon of configurational splitting of giant dipole resonance in light nuclei, which was first discovered a quarter of a century ago and induced pro found changes in the commonly accepted understanding of the structure of light nuclei and the mechanisms of their highenergy excitations. The experiments that led to the discovery of this phenomenon are described. The present status of the phenomenon of the configurational splitting of nuclear giant dipole resonance is dis cussed and directions of its future studies are outlined.
Show AbstractThe spacecharge problem is considered in the hydrodynamic approximation. The problem is formulated in terms of the chargedensity, $\rho$, and the vector velocity field, $v$, (the $\rho v$ statement). In contrast to the $Dv$ statement, the ρv statement can be used for asymmetric chargedensity distributions. A formal solution to a boundary value problem is described and its properties are considered.
Show AbstractA general operational method, which is based on the developed technique of the inverse derivative operator, for solving a wide range of problems described by some classes of differential equations is represented. The inverse derivative operators for solving a number of differential equations are constructed and used. The operational identities are derived with the use of the inverse derivative operator, integral transformations, and generalized forms of orthogonal polynomials and special functions. Examples of solving various partial differential equations, such as equations of heat conduction and diffusion, as well as the Fokker-Planck equation, etc. are given. The application of the operational approach to solving a number of physical problems, among them problems related to the motion of charged particles in external field, is demonstrated.
Show AbstractPropagation of the magnetic field to the periphery of the galactic disc and the possibility of its transfer using a dynamo wave are studied. For this purpose, a system of two equations with a small parameter of high-order derivatives is considered. Its important feature is that for a certain value of the independent variable the stability of the roots of the degenerate equation changes. For this problem the numerical velocity values of transition layers are obtained. The problem of their possible penetration beyond the bounds of the point of stability change is studied. A similar scalar equation is studied, for which asymptotic estimates of the front propagation velocity can be obtained. These estimates are in good agreement with the numerical simulation results.
Show AbstractA parametric expression for the Gibbs potential was found using the generalized Van Laar method for the free energy of a system. Since this expression is used in order to analyze the behavior of a system in the supercritical region, the well-studied system of soft spheres was selected as a reference system. This allows one to find thermodynamic characteristics from known virial coefficients of the system and available information on the position of the critical point. The lines of the extremes for the second derivatives of the Gibbs potential were calculated for a system with the Lennard-Jones interaction potential. The line of the maxima of the isothermal compressibility and the line of the maxima of the constant-pressure heat capacity were compared with the molecular-dynamics data. The good agreement between the theoretical calculations, which are based on analytic functions in this domain, and the molecular-dynamics data shows the absence of a third-order phase transition in the supercritical region.
Show AbstractA donor-acceptor nanocluster under an IR radiation field (λ = 16–18 nm) is reported. The donor molecule in the nanocluster contains a polar C$_n$H$_{2n}$ substructure that serves an IR antenna for this radiation. The accepter is a dimer of nonpolar pyrene molecules. The induced dipole moments of the pyrene molecules that arise in the field of the IR antenna dipole moment is studied. It is assumed that the induced dipole moment of each pyrene molecule in the dimer produces an extra electrostatic field that affects the neighboring pyrene molecule in the dimer. The analytical expressions for this process are obtained and the relevant analysis of the dynamic phenomena is performed. It is established that the value of the induced molecular dipole moment in pyrene dimer is much larger than the same value in the pyrene monomer. This leads to the increasing probability of the induction processes in nanoclusters in comparison with the same processes in nanoclusters with a single pyrene molecule in accepters.
Show AbstractThis article describes the mathematical apparatus of original software that was developed by the authors for calculations of the radiation shielding and the fields of bremsstrahlung and scattered radiation of linear electron accelerators, which is adapted to a wide range of applications. The proposed program is based on the Monte Carlo method; this allows one to carry out a statistical calculation of the bremsstrahlung photon flux and to choose the trajectories of bremsstrahlung photons using a random number generator. The program is intended for the design of beam collimation systems, the calculation of complex radiation shielding profiles with labyrinths and tunnels, the optimization of the size of shielding barriers, assessment of the expected detection system response, and the prediction of the dose distribution in a cross section of a protected object. For verification of the reliability of calculations that are carried out by using this original software, the results of numerical experiments with the proposed code were compared to the results that were obtained using the Monte Carlo code MCNP version 4C3 for backscattered photons and forward transmitted bremsstrahlung photons with a boundary energy of 24 MeV for a number of materials and various thicknesses.
Show AbstractThe structure of the spatial spectra from the second harmonic (SH) of yttrium-aluminum-garnet neodymium laser radiation during quasi-phase-matched generation is studied in a spatially inhomogeneous nonlinear medium. Based on the example of the formation of the strontium-barium niobate (SBN) domain structure a theoretical model that describes the angular distribution of the intensity of the noncollinear SH generated in the polydomain crystal with stochastically distributed domains is proposed. It is shown that the characteristic spatial domain sizes can be found from the second-harmonic intensities and that the density of the domain distribution is described by the Weibull-Gnedenko distribution.
Show AbstractThe problem of the fabrication of third-generation high-temperature superconductors (HTSCs) that are designed for the transmission of electric energy and the creation of nanoelectronic devices is studied in this work. The issues of the fabrication of dielectric substrates for the third generation wires are considered. The technology of HTSC film deposition on the quartz substrates is presented. Complex studies of sputtering of the buffer and superconducting YBa$_2$Cu$_3$O$_{7-\delta}$(YBCO) layers were performed. The results of studies of electrophysical properties of the HTSC films on the quartz substrates are discussed.
Show AbstractIt is proposed to construct the kinematics of complex systems (systems of the third type) based on simulation of the motion of the state vector of the system $x(t)$ in the phase space of states. A new concept of stationary modes of these systems, which is different from the analog in mechanics (when $dx/dt \neq 0$) and statistical interpretation (when the distribution function $f(x)$ does not change significantly), is introduced. For systems of the third type, $dx/dt \neq 0$ is always met and $f(x)$ for all consecutive samples (e.g., cardiointervals) varies continuously. A unit for calculation of the motion of centers of quasi-attractors ($QA$, regions of phase space, where $x(t)$ changes continuously) is presented. The concepts of velocity and acceleration of evolution are introduced. The concepts of uncertainty of the first and second kinds are given. Examples of rectilinear and curvilinear motion of $x(t)$ in the phase space (from gerontology for groups of women of different ages) are given.
Show AbstractThis article is devoted to solving the problem of the plasma temperature distribution along a magnetic tube, one end of which is in the chromosphere, while the other is in the corona. The plasma temperature dependences of the density, pressure, and velocity of plasma are determined for various velocities of the plasma flow, which are given at the lower boundary of the transition region. In the case where gravitation can be neglected, these dependences are derived in the analytical form. The existence of three velocity ranges is demonstrated, for which: (a) the excitation of shock waves in the transition region is possible, (b) the transition region can be considered in the classical collisional approximation, and (c) the plasma heating process is close to the $p = \text{const}$ mode and the calculated hard ultraviolet radiation coincides well with modern satellite observations. Based on the obtained results, we concluded that generally in the presence of plasma flows, the quiet transition region between the corona and the chromosphere should be considered in the classical approximation of Coulomb collisions.
Show AbstractA description of the project of the Tunka-Grande scintillation complex is provided. The prospects of studying the energy spectrum and mass composition of the primary cosmic rays during simultaneous registration of the Cherenkov, electron, and muon components of extensive air showers are discussed.
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