Том 60, № 12 (2018)

Lagrangians of the field-theory model of a scalar field are considered as 4-forms on a Riemannian manifold. The model is constructed on the basis of the Hodge inner product, this latter being an analog of the scalar product of two functions. Including the basis fields in the action of the terms with tetrads makes it possible to reproduce the Klein–Gordon equation and the Maxwell equations, and also the Einstein–Hilbert action. We conjecture that the principle of construction of the Lagrangians as 4-forms can give a criterion restricting possible forms of the field-theory models.

The Fokker–Planck equation in one-dimensional spacetime with quadratically nonlinear nonlocal drift in the quasilocal approximation is reduced with the help of scaling of the coordinates and time to a partial differential equation with a third derivative in the spatial variable. Determining equations for the symmetries of the reduced equation are derived and the Lie symmetries are found. A group invariant solution having the form of a traveling wave is found. Within the framework of Adomian’s iterative method, the first iterations of an approximate solution of the Cauchy problem are obtained. Two illustrative examples of exact solutions are found.

In the modified potential cluster model, the possibility of describing the astrophysical S-factor of radiative p⁷Ве→⁸Bγ capture to the ground state of the ⁸B nucleus at energies from 10 keV to 1 MeV is considered. Potentials of intercluster interactions, matched to the spectra of the ⁸B nucleus for scattering processes, and the potential of the bound 3Р2 ground state in the p7Ве cluster channel are constructed. The resonance in the 3P1 scattering wave at the energy 0.722 MeV, which leads to an М1-transition to the ground state, is considered. Total cross sections and the reaction rate of p7Ве capture are calculated in the temperature range from 0.01·Т9 to 5·Т9.

The problem of constructing alternative Hamiltonian formulations in the extended Chern–Simons theory with higher derivatives is considered. It is shown that the fourth-order extended theory admits a four-parameter series of alternative Hamiltonians which can be bounded from below, even if the canonical energy of the model is unbounded from below.

The paper deals with the electronic heat capacity of iron monosilicide FeSi subjected to semiconductor–metal thermal transition during which the formation of its spintronic properties is observed. The proposed model which considers pd-hybridization of strongly correlated d-electrons with non-correlated p-electrons, demonstrates a connection of their contribution to heat capacity in the insulator phase with paramagnon effects and fluctuations of occupation numbers for p- and d-states. In a slitless state, the temperature curve of heat capacity is characterized by a maximum appeared due to normalization of the electron density of states using fluctuating exchange fields. At higher temperatures, a linear growth in heat capacity occurs due to paramagnon effects. The correlation between the model parameters and the first-principles calculation provides the electron contribution to heat capacity, which is obtained from the experimental results on phonon heat capacity. Anharmonicity of phonons is connected merely with the thermal expansion of the crystal lattice.

The paper deals with crystallization kinetics of amorphous AgInS₂ film. The dependence between lnln(V₀ / (V₀ –V_t) and lnt is obtained for 423, 448 and 468 K temperatures, which shows a linear arrangement of points for these temperatures, i.e. 2.80 2.87 and 2.93, respectively. The approximate equality of these values indicates that during AgInS₂ film crystallization, a two-dimensional crystal growth occurs and the reaction rate constant equals (1/3π) \( {\eta}_n{\eta}_c^2. \)

The structural and phase state of the samples obtained by co-grinding of Ti and Cu powders under different conditions (with graphite, in petroleum ether, and in xylene) is investigated. It is demonstrated that after thermal treatment of powders obtained by milling of titanium, copper, and graphite in petroleum ether, both cubic titanium carbide and hexagonal titanium carbohydride are formed, whereas by milling without graphite, only hexagonal carbohydride possessing high thermal stability is formed. CuTi and CuTi₂ intermetallic phases are formed under all examined conditions of mechanosynthesis.

Mechanical properties of thin surface layers and coatings are commonly studied using instrumented indentation and scratch testing, where the mechanical response of the coating – substrate system essentially depends on the substrate material. It is quite difficult to distinguish this dependence and take it into account in the course of full-scale experiments due to a multivariative and nonlinear character of the influence. In this study the process of instrumented indentation of a hardening coating formed on different substrates is investigated numerically by the method of movable cellular automata. As a result of modeling, we identified the features of the substrate material influence on the derived mechanical characteristics of the coating – substrate systems and the processes of their deformation and fracture.

The behavior of an electronic subsystem is investigated in the course of formation and development of a memory channel in solid solutions of the TlInTe2–TlYbTe2 system. An analysis of the current-voltage characteristics allows getting an insight into the reason for a sharp change in electrical conductance of the specimens under study during their transition from the high-resistance to high-conductance state and the reasons for the well known instability of threshold converters, which makes it possible to design devices with high threshold voltage stability.

A physico-mathematical model of the processes of radiation-induced charging of dielectric materials with open surfaces, irradiated with monoenergetic electrons in the energy range 10–30 keV, is described. The model takes into account the relationship between the processes of surface and bulk charging for the given conditions of the experimental design, which accounts for the effect of anomalously long charging of dielectrics after the incident energy of primary electrons during charging is reduced to below the second critical energy for the secondary electronic emission coefficient. The initial fast phase of charging a high-resistivity dielectric material (Al₂O₃) is investigated. It is shown that as the incident electron energy is approaching the second critical energy during charging, the secondary electronic emission is partially suppressed due to negative charging of the open surface of the dielectric and formation of a near-surface inversion electrical field retarding the electronic emission yield.

A variant of the method of partial waveguide filling is considered in which a sample is put into a waveguide through holes in wide waveguide walls at the distance equal to a quarter of the wavelength in the waveguide from a short-circuiter, and the total input impedance of the sample in the waveguide is directly measured. The equivalent circuit of the sample is found both without and with account of the hole. It is demonstrated that consideration of the edge effect makes it possible to obtain more exact values of the dielectric permittivity.

Ink compositions for inkjet printing based on poly(9.9-dioctylfluorene) and its alcohol-soluble analog are created. Current–voltage, brightness–voltage, and spectral characteristics are compared for one- and twolayer polymer structures of organic light-emitting diodes. It is shown that the efficiency of the alcohol-soluble polyfluorene analog is higher compared to poly(9.9-dioctylfluorene), and the possibility of viscosity optimization is higher compared to aromatic chlorinated solvents.

For a hybrid model of the low-current discharge considering, along with direct ionization of the mixture components by electrons, the Penning ionization of mercury atoms by metastable argon atoms, the ionization coefficient in the argon–mercury mixture used in illuminating lamps is calculated. The analytical approximation formula describing the dependence of the ionization coefficient of the mixture on the reduced electric field strength and temperature is obtained for sufficiently wide ranges of their variations, and its accuracy is estimated. It is demonstrated that the discharge ignition voltage calculated using this formula is in agreement with the results of simulation and the available experimental data.

Simulation by the Monte Carlo method is widely used to calculate the character of ionizing radiation interaction with substance. A wide variety of programs based on the given method allows users to choose the most suitable package for solving computational problems. In turn, it is important to know exactly restrictions of numerical systems to avoid gross errors. Results of estimation of the feasibility of application of the program PCLab (Computer Laboratory, version 9.9) for numerical simulation of the electron energy distribution absorbed in beryllium, aluminum, gold, and water for industrial, research, and clinical beams are presented. The data obtained using programs ITS and Geant4 being the most popular software packages for solving the given problems and the program PCLab are presented in the graphic form. A comparison and an analysis of the results obtained demonstrate the feasibility of application of the program PCLab for simulation of the absorbed energy distribution and dose of electrons in various materials for energies in the range 1–20 MeV.

A comparative investigation of the structure of an aluminum-manganese alloy is performed after its friction stir welding and sliding friction. Using the methods of optical and electron microscopy, it is shown that during friction identical ultrafine-grained structures are formed in the weld nugget and in the surface layer, in which the grains measure ~ 5 μm irrespective of the initial grain size of the alloy. An assumption is made that the microstructure during both processes under study is formed by the mechanism of rotational plasticity.

An overview of the scientific literature since 2000 on InN doping with impurities giving it ferromagnetic properties and on the magnetic properties of InN is presented. According to theoretical and experimental studies, InN doped with transition metals and rare earth elements possesses ferromagnetic properties at temperatures above room temperature and is a material promising for spintronics.

Diurnal dynamics of the standard deviation (SD) of three wind velocity components measured with a minisodar in the atmospheric boundary layer is analyzed. Statistical analysis of measurement data demonstrates that the SDs for x- and y-components σ_x and σ_y lie in the range from 0.2 to 4 m/s, and σ_z = 0.1–1.2 m/s. The increase of σ_x and σ_y with the altitude is described sufficiently well by a power law with exponent changing from 0.22 to 1.3 depending on time of day, and σ_z increases by a linear law. Approximation constants are determined and errors of their application are estimated. It is found that the maximal diurnal spread of SD values is 56% for σ_x and σ_y and 94% for σ_z. The established physical laws and the obtained approximation constants allow the diurnal dynamics of the SDs for three wind velocity components in the atmospheric boundary layer to be determined and can be recommended for application in models of the atmospheric boundary layer.