Scaling solutions in Galileon cosmology

We investigate a special case ofGalileon cosmology containing only the second and third terms with a power-law potential. A new special scaling-like solution in such a kind of theory was found. We also investigate some properties of this solution including its stability.     

The influence of elastic and ionization cross-section approximations on the result of Monte Carlo calculations

A Monte Carlo program has been developed on the basis of a Mott cross-section and knock-on model. The use of this program for the set of the film-substrate type systems shows that there is some difference between the calculated and experimental x-ray depth distribution. To clear up the reasons for the discrepancies, the Monte Carlo model is investigated by calculating the various physical quantities associated with the electron distribution in homogeneous bulk and film specimens and by comparing them with the known experimental data. The influence of the elastic and ionization cross-section approximation on the electron distribution in target is studied.     

Fine particles of lanthanum-and cobalt-doped strontium hexaferrite prepared through glass crystallization

Glass of nominal composition Sr_0.6La_0.4Fe_11.6Co_0.4O₁₉ + 12SrB₂O₄ was prepared by rapidly quenching an oxide melt and was then heat-treated at temperatures from 550 to 900°C to give glass-ceramics containing fine lanthanum-and cobalt-doped strontium hexaferrite particles and microcrystalline SrB₂O₄. The materials were characterized by x-ray diffraction, scanning electron microscopy, electron probe x-ray microanalysis, and magnetic measurements. The coercivity of the glass-ceramic samples was shown to increase up to 427 kA/m with increasing heat-treatment temperature. The saturation magnetization of the samples increases up to 25.0 A m²/kg as the heat-treatment temperature is raised to 750°C, and decreases slightly at higher temperatures. Dissolving the nonmagnetic matrix of the glass-ceramic prepared at 900°C, we obtained submicron powder of composition Sr_0.88La_0.12Fe_10.74Co_0.47O_y, as determined by x-ray microanalysis.     

A condition imposed on the electromagnetic polarizability of a bianisotropic lossless scatterer

In the dipole and local field approximations, electromagnetic scatterers are modeled in terms of the polarizability tensor. The matrix elements of this tensor, which are determined by the scatterer geometry, are complex even in the absence of losses in the material. There is a criterion that the polarizability tensor must obey if the scatterers possess no dissipative losses. This condition, derived here for bianisotropic scatterers, can be applied to analytical modeling of periodic structures composed of such scattering inclusions.     

Angular stabilisation of resonant frequency of artificial magnetic conductors for TE-incidence

Two novel artificial magnetic conductors (high-impedance surfaces) are suggested that stabilise the resonant frequency of the structure with respect to variations of the angle of incidence of TE-polarised incident electromagnetic waves. The performance is compared to that of the well-known mushroom structure, both in theory and experiment. A possible explanation for the stabilising effect is presented.     

Subwavelength imaging in a superlens of plasmon nanospheres

A structure comprising two lattices of silver or gold nanospheres is considered. It is shown that this structure can be used as a superlens capable of providing subwavelength imaging of a point source and a sub-wavelength spatial resolution of two sources at a distance within one wavelength.     

Vector circuit method applied for chiral slab waveguides

Eigenvalue equations for the propagation constants of lightwaves in open chiral slab waveguides are derived. The analysis makes use of vector circuit modeling of a chiral slab, the method which has been previously applied for calculating reflection and transmission of electromagnetic waves in chiral multilayer structures. The general eigenvalue equation for the guide which is valid for arbitrary boundary impedance conditions on the slab interfaces is derived, and three special cases are analyzed in detail: an open chiral dielectric slab with dielectric half spaces of the opposite sides of the slab, a chiral slab on an ideally conducting surface, and a chiral slab on an ideal magnetic surface. The theory is visualized by calculated dispersion curves indicating the chirality effect on the wave propagation characteristics     

An Automated Millimeter-Wave Resonator Spectrometer for Investigating the Small Absorption in Gases

A resonator spectrometer developed by the Institute of Applied Physics for broadband measurements of the radiation absorption in gases is described. The acquisition and processing of experimental data, as well as the radiation source of this spectrometer, are controlled by the automation system. The setup is used in real-time measurements of the molecular absorption lines in gases at near-atmospheric pressures, specifically, for the investigation of radiation absorption in the open atmosphere.     

Evaluation of the minimum face clearance of a high-speed gas-lubricated bearing with Navier slip boundary conditions under random excitations

Motivated by ongoing developments in aero-engine technology, a model for a coupled gas-lubricated bearing is developed in terms of an extended dynamical system. A slip boundary condition, characterised by a slip length, is incorporated on the bearing faces which can be relevant for operation in non-ideal extreme conditions, notably where external vibrations or disturbances could destabilise the bearing. A modified Reynolds equation is formulated to model the gas flow, retaining the effects of centrifugal inertia which is increasingly important for high-speed operation, and is coupled to the structural equations; spring-mass-damper systems model the axial stator and rotor displacements. A novel model is developed corresponding to a bearing experiencing an external random force to evaluate the resulting induced displacements of the bearing components. The minimum face clearance is obtained from a mapping solver for the modified Reynolds equation and structural equations simultaneously. In the case of random excitations, the solver is combined with a Monte Carlo technique. Evaluation of the average value of the minimum gap and the probability of the gap reaching a prescribed tolerance are provided. Extensive insight is given on the effect of key bearing parameters on the corresponding bearing dynamics.