Vol 59, No 3 (2016)

Non-force and force electromagnetic fields, their generation, and application for an explanation of some physical effects well-known for a long time are considered.

Stephani cosmological models are considered which describe spacetimes for a shear-free matter distribution and include Friedmann models as a particular case. The possibility is considered of constructing cosmological models in which a change of sign of the acceleration of the Universe expansion arises only due to curvature.

The precession of the perihelion of Mercury’s orbit for 100 years in the gravitational field of the Sun and the planets has been numerically modeled within the framework of a generalized law of universal gravitation with refined data on the parameters of the orbits of the planets (including the asteroid belt and Pluto), and also the gravitational constant and with a smaller iteration step (0.0002 s). The calculations were performed with enhanced computational accuracy. It has been shown that the average precession of Mercury’s orbit in 100 years within the framework of the generalized law of universal gravitation comprises ~565.3''. This is less than the observed shift of the perihelion by about 8.8''. The observed shift of the perihelion, as is well known, comprises ~574.1''. It is not ruled out that inside Mercury’s orbit some unknown undetected object (or several such objects) of small size remains to be found.

The problem of the propagation of ultrashort pulses, including both two-dimensional and three-dimensional pulses, in a Fermi liquid is considered with the help of representations of the duality of gauge gravitation. The electromagnetic field is considered classically on the basis of the Maxwell equations. The effective equation so obtained is analyzed numerically and the dynamics of the state of the electromagnetic field are elucidated in the planar case, and also when it is localized in two/three spatial dimensions.

The special features of the structure of secular resonances in the near-earth orbital space bounded by the following range of orbital parameters: semimajor axis from 8000 to 55 000 km, inclination from 0 to 90°, and eccentricity equal to 0.01, 0.6, and 0.8 are analyzed. The influence of stable and unstable secular resonances on the long-term orbital evolution of near-earth space objects is also considered. It is demonstrated that the joint effect of the stable secular resonances of different spectral classes does not violate the regularity of motion. The chaoticity arises when stable secular resonances of one spectral class are imposed.

The object of the study is the C₂D₄ molecule, as it is important to know its properties to address numerous problems of molecular physics. The analysis of high-resolution spectra of the deuterated ethylene molecule was made in the range of 600–1200 cm^–1, specifically bands ν₇ and ν₁₂. The results obtained were used to determine high-accurate values of the vibrational-rotational levels of the ground vibrational state of the C₂D₄ molecule.

It is demonstrated that propagation of the soliton described by the Boussinesq equation along a linear defect of the crystal structure leads to radiation of sound waves (analog of the Vavilov–Cherenkov effect). Radiation that has a continuous spectrum diverges conically from the dislocation line, and the apex angle of the cone is determined by the ratio of the sound speed in the crystal to the soliton speed. With increasing soliton speed, the maximum of the spectral flux density of sound energy is displaced toward higher frequencies. An analytical expression for energy losses is derived.

Composite Al–Al₂O₃ and Al–AlN nanoparticles were synthesized via electric explosion of aluminum wires in an argon–oxygen gas mixture and in nitrogen. The parameters of electric explosion and gas medium affect the size and relative content of nitride and aluminum oxide in the nanoparticles. Processes of forming chemical compounds during aluminum oxidation at the contact surface between explosive products and gas and of nitrogen diffusions into the nanoparticles of the condensed phase are considered.

The influence of introduction of particles of detonation-synthesized nanodiamonds into composites and aluminum-base light alloys on their physical and mechanical properties is analyzed. The data on microstructure and physical and mechanical properties of composites and cast aluminum alloys reinforced with diamond nanoparticles are presented. The introduction of nanoparticles is shown to result in a significant improvement of the material properties.

A modified expression for the Andreev reflection coefficient is derived taking into account strong electronphonon interactions. A dependence of the superconducting order parameter ∆_σ is numerically modeled for magnesium diboride. The current-voltage characteristics and the dI/dV spectra of the dynamic conductivity of superconductor-normal metal-superconductor (SNS) contacts based on strongly coupled superconductors are calculated for the Averin–Bardas model using the modified Andreev reflection coefficient (on an example of magnesium diboride). Calculations are performed for the mode of high transparency (0.9–0.98). The special features of the SNS contacts based on strongly coupled superconductors are shown.

Results of experimental investigations of amplitude-temporal and spectral characteristics of radiation of a pulse-periodic discharge plasma initiated in nitrogen by runaway electrons are presented. The discharge was initiated by high-voltage nanosecond voltage pulses with repetition frequency of 60 Hz in a sharply inhomogeneous electric field in a gap between the conic potential cathode and the planar grounded aluminum anode. It is established that intensive lines of Al I atoms and Al II atomic ions, lines of N I atoms and N II ions, bands of the first (1⁺) and second positive (2⁺) nitrogen systems, as well as bands of cyanogen CN are observed in the emission spectrum of the discharge plasma under the given excitation conditions.

The special features inherent in the development of high-temperature deformation and structural evolution in materials are investigated, using a VT22 titanium alloy of the transition class (Ti – 4.74 mass% Al – 5.57 mass% Mo – 5.04 mass% V) subjected to helical rolling + aging as an example. This treatment is found to give rise to an intragrain fine acicular martensite structure with fine inclusions of α-phase particles of size ~1 μm. It is shown that in the alloy undergoing plastic deformation at temperatures approaching the polymorphic transformation temperature, the elongation to failure is in excess of 300%. The high plasticity of the alloy in the conditions considered is likely to be due to vigorous development of phase transformations and intensification of diffusion-controlled processes, including the effects of the evolution of the dislocation structure, growth of subgrains, and formation of new grains in the bulk of the pre-existing ones during plastic deformation.

Electrical and optical studies of defect structure of HgCdTe films grown by molecular beam epitaxy (MBE) are performed. It is shown that the peculiarity of these films is the presence of neutral defects formed at the growth stage and inherent to the material grown by MBE. It is assumed that these neutral defects are the Te nanocomplexes. Under ion milling, they are activated by mercury interstitials and form the donor centers with the concentration of 10¹⁷ cm^–3, which makes it possible to detect such defects by measurements of electrical parameters of the material. Under doping of HgCdTe with arsenic using high temperature cracking, the As₂ dimers are present in the arsenic flow and block the neutral Te nanocomplexes to form donor As₂Te₃ complexes. The results of electrical studies are compared with the results of studies carried out by micro-Raman spectroscopy.