Hutchinson's shear coefficient for anisotropic beams

Timoshenko's theory of vibrating beams requires a shear correction factor to correctly take into account the effects of shear deformation for different beam cross-sections. This correction is crucial for a precise determination of the shear modulus from the resonant frequencies. Hutchinson's beam theory is used to derive a new shear correction coefficient for anisotropic materials. A comparison is made with other shear coefficients for anisotropic materials published in the literature. Computer-simulated spectra are used to validate the new anisotropic shear correction coefficient.     

Vector coupled-wave method for analyzing diffraction by multilayer gratings

In the framework of the matrix formulation of the coupled plane wave approach, a method is proposed for increasing the stability of the numerical analysis of vector electromagnetic fields in periodic structures, including dielectric and metallic anisotropic layers and relief boundaries.     

Ion source with a cold magnetron cathode and magnetic plasma compression

The operating principles, design, and characteristics of an ion source with a cold magnetron cathode and magnetic plasma compression are described. The source is intended for the injector of a linear proton accelerator.     

Calculation of the vibrational spectra of copper crystals with vacancies

The local vibrational spectra of copper crystals containing vacancies are calculated using the pair atomic potential derived in the framework of the resonance pseudopotential theory. The calculations are performed by a recursive method with due regard for the symmetry of the defect region. The frequencies of the vacancy-induced resonance vibrations of different symmetries are determined.     

Transition flow of rarefied gases: Current models and methods of simulation

Transition (molecular-viscous) isothermal channel flow of rarefied gases is considered. Present-day engineering physical models of transition gas flow and methods of simulation are analyzed and verified in terms of the kinetic theory on the micro-and macrolevels.     

The action of an electron beam on dust structures in a plasma

The action of an electron beam on ordered dust structures in glow and low-pressure RF discharges was studied experimentally. The electron beam produces destruction and dynamic displacement of the dust structure. In the center of a dust structure, an electron beam with a low electron energy (tens of eV) at currents up to 1 mA caused structural disordering and “melting” in the region of its action but did not excite external crystal regions. Local action of an electron beam with a high electron energy (25 keV) and a beam current above 10 mA caused deformation of the whole dust structure and shifted it in the horizontal direction so that it was carried away from the RF discharge zone. The effect of dust structure displacements can be used to locally remove particles from a plasma.     

A vector percolation modeling of oil–gas relative permeabilities

We presented exact analytical formulae and numerical calculation of diffusitivity curves with different law for a local pore behavior and have obtained critical exponent, different from conductivity. The connectivity percolation theory was built only on the conductivity, (the diffusion critical exponent was supposed to be equal to the conductivity exponent) and therefore sees only one side of problem-the scalar side. In many topological problems involving mechanical properties and fluid flow the connectivity scalar percolation geometry does not enough to apply.

One of the most useful aspects of percolation is that many very complicated systems have the same behavior with the same critical exponents. Universality of vector percolation is shown in the coincidence between the experimental measured relative hydraulic permeability of fluid and gas flow through unconsolidated sand and effective conductivity and diffusitivity curves of the bond–site percolation models. Comparisons of our calculation results to natural matches are quite good. We have argued that experimental data may be interpreted as a variant of pure vector percolation and to belong to the same universality class.     

Algebraic algorithms for the analysis of mechanical trusses

Infinite periodic lattices can be used as models for analyzing and understanding various properties of mechanical truss constructions with periodic structures. For infinite lattices, the problems of connectivity and stability are nontrivial from the mathematical point of view and have not been addressed adequately in the literature. In this paper, we will present a set of algebraic algorithms, which are based on ideal theory, to solve such problems.

For the understanding of the notion ``complicated three-dimensional lattices', it is essential to have this paper with colored figures.

     

Specific features of magnetoabsorption resulting from exactly taking into account the electronic band spectrum

Effects related to the periodicity of the carrier dispersion relation in the reciprocal space are investigated. It is shown that, under certain conditions, magnetoabsorption in crystals exhibiting such dispersion significantly differs from the magnetoabsorption in crystals characterized by a parabolic dispersion relation for charge carriers.