Vol 59, No 9 (2017)

Fourier spectrum of the ¹³CH₃D molecule in the spectral range 4200–4400 cm^–1, where the ν₃ + ν₄ combination band is located, is investigated for the first time. Experimental data obtained are used to determine the effective Hamiltonian parameters of the ¹³CH₃D molecule.

High resolution (0.0025 cm^–1) spectrum of the ¹³C₂H₄ molecule recorded in the 2330–2500 cm^–1 spectral region with a Bruker 120HR Fourier spectrometer is theoretically analyzed. The spectroscopic parameters of the (v₂ = v₁₀ = 1, B_2u) vibrational state of the molecule are determined for the first time by fitting the experimental data that allow the rotational energy values (529 rovibrational energies corresponding to 2400 transitions with J^max = 30 and K_a^max = 13) to be reproduced with accuracy close to experimental uncertainties.

Within the framework of the general theory of relativity, we investigate all possible astrophysical and geometrical effects induced by self-gravitating extreme matter in the form of ideal fluids with limiting and superlimiting equations of state or in the form of strongly nonlinear physical fields. Attention is directed to the possibility of the formation of wormholes and other unusual astrophysical objects.

Signals in the infra-low frequency range in the electric and geomagnetic fields of the Earth have been detected, corresponding to frequencies of gravitational waves (GWs) emitted by a series of binary star systems (BSS). The coherence of the detected signals has been investigated. The amplitude characteristics of signals in the electric and geomagnetic fields at GW frequencies of BSS are estimated. The estimates of the amplitudes of the detected signals are in line with model estimates.

Within the framework of the modified cluster model with forbidden states and classification of states according to the Young tableaux, the possibility is considered of describing the available experimental data for the total cross sections of n⁸Li capture at thermal and astrophysical energies.

The present work is devoted to a study of motion of near-Earth asteroids (NEA) 2002 VE68 and 2013 ND15 moving in the vicinity of the 1:1 resonance with Venus. To construct the probability domain of these NEA, 10 thousand clones covering the initial probability domain of the object were used. The investigation time intervals chosen individually are 4500 and 1520 years, respectively. The orbit of asteroid 2013 ND15 is illdefined that allows no conclusion to be made on its capture in a resonance. The given object regularly approaches to Mercury, Venus, and the Earth thereby causing a substantial growth of the probability domain. Our study shows that new observations of the asteroid from the Earth surface are impossible till 2021. An analysis of the evolution of the average MEGNO parameter demonstrates that the predictability time of motion of the given object is about 250 years. Asteroid 2002 VE68 behaves differently. A study of perturbation structure demonstrates that for this object it is necessary to take into account the influence of major planets, the Moon, the Sun oblateness, and relativistic effects of the Sun. On the entire investigation time interval the asteroid moves in the vicinity of stable resonance and its critical argument librates. Asteroid 2002 VE68 approaches to Mercury and Venus, but not very close. The predictability time of motion is about 800 years.

The exposure of the alkali-halide crystals to ionizing radiation leads to the destruction of their structure, the emergence of radiation defects, and the formation of the electron and hole color centers. Destruction of the color centers upon heating is accompanied by the crystal bleaching, luminescence, and radio-frequency electromagnetic emission (REME). After complete thermal bleaching of the crystal, radiation defects are not completely annealed, as the electrons and holes released from the color centers by heating leave charged and locally uncompensated defects. Clusters of these “pre centers” lead to electric microheterogeneity of the crystal, the formation of a quasi-electret state, and the emergence of micro-discharges accompanied by radio emission. The generation of REME associated with residual defectiveness, is a manifestation of the effect of radiation “memory” in dielectrics.

The effect of nanopowders on the burning rate varying with the metal content in mixtures of different high energy composition is investigated. Experiments were performed on compositions based on an active tetrazol binder and electroexplosive nanoaluminum with addition of copper, nickel, or iron nanopowders, and of Al–Ni, Al–Cu, or Al–Fe composite nanoparticles produced by electrical explosion of heterogeneous metal wires. The results obtained from thermogravimetric analysis of model metal-based compositions are presented. The advantages of the composite nanoparticles and the possibility of using them in high energy materials are discussed.

The authors formulated an understanding of the order parameter and built a kinetic model for the nonequilibrium first-order “solid body – liquid” phase transition stimulated by the impact of the volumetric heat source. Analytical solutions for kinetic equations were found, and it was demonstrated that depending on the phase transition rate “surface” and “bulk” melting mechanisms are implemented.

The paper considers the results of measuring the elastic parameters (ponderomotive elasticity coefficient, oscillation frequency, attenuation coefficient) of the oscillatory system with an inertial element that is a magnetic fluid column retained in a tube due to magnetic levitation in a strong magnetic field. Elasticity is provided by the ponderomotive force which affects the upper and lower thin layers of the fluid column. Measurement results of vibration parameters of the oscillatory system can be useful for the investigations of magnetophoresis and aggregation of nanoparticles in magnetic fluids.

A quasistationary solution of a two-component system of first-order telegraph equations on an interval with time-dependent conditions is constructed, where these conditions are prescribed at interior points of the interval. Application of the obtained solution as a criterion for leakage detection is considered.

An experimental study of the dynamics of formation of plasma jets and ion beams in laser-induced low-voltage discharges with high rates of current rise has been performed. It has been found that for given discharge characteristics (energy store voltage, discharge current, current rise rate, and discharge gap spacing) there exist optimum initial conditions, determined by the characteristics of the laser radiation, that provide stable single pinching of the cathode plasma jet at its maximum compression. Increasing the ion density and decreasing the temperature of the foreplasma by reducing the laser radiation power density at the cathode due to an increase in laser pulse duration improves the stability of the plasma pinching at a lower energy input.

In this work, we studied temperature dependences of the resistivity and current-voltage characteristics of amorphous thin films based on the materials of a Ge–Sb–Te system of compositions GeSb₄Te₇ (GST147), GeSb₂Te₄ (GST124), and Ge₂Sb₂Te₅ (GST225) applied in the phase change memory devices. The effect of changes in the composition of thin films on the crystallization temperature, resistivity of films in amorphous and crystalline states, and on the activation energy of conductivity is determined. It is found that the peculiarity of these materials is the mechanism of two-channel conductivity where the contribution to the conductivity is made by charge carriers excited into localized states in the band tails and by carriers of the delocalized states in the valence band.

A mathematical model of a thermal explosion in a mechanically pre-activated Ti–Ni system is constructed in a macroscopic approximation. It is found out that preliminary mechanical activation considerably accelerates the reaction product synthesis. Using the experimental data obtained earlier, the thermal and kinetic constants of the synthesis are determined.

Acoustic emission of the destruction zone formed upon exposure of the metal surface to pulsed laser radiation is considered. A dependence of the waveform and spectrum of acoustic vibrations on the parameters of the irradiated material and a law of increase in the crater depth are determined. It is revealed that for the copper sample surface irradiated by the laser pulse with duration of ~20 μs, the time of growth of the destruction zone is approximately 40 μs, which is in good agreement with the time of existence of plasma formation at the surface of the target treated by laser plasma (~50 μs).

A method for solving physical problems is suggested in which the general solution of a differential equation in partial derivatives is written in the form of decomposition in spherical harmonics with indefinite coefficients. Values of these coefficients are determined from a comparison of the decomposition with a solution obtained for any simplest particular case of the examined problem. The efficiency of the method is demonstrated on an example of calculation of electromagnetic fields generated by a current-carrying circular wire. The formulas obtained can be used to analyze paths in the near-field magnetic (magnetically inductive) communication systems working in moderately conductive media, for example, in sea water.

The problem of state prediction for linear dynamic systems with discrete time is considered in the presence of unknown input and inaccurately specified parameters in the model. An algorithm with compensation for the constant component and estimation of the unknown variable input component by the least squares method is suggested. Results of statistical simulation are presented. The algorithm can be used for solving problems of processing information obtained as a result of observations over physical processes.