Adhesion in elastic-plastic spherical microcontact

An elastic-plastic adhesion model for a metallic deformable sphere pressed by a rigid flat is presented. Analytical dimensionless expressions for the local separation outside the contact area and for the adhesion force are provided covering a large range of interference values from a point contact to a fully plastic contact. Two main dimensionless parameters of the problem are identified and their effect on the adhesion is investigated. The significance of the adhesion in the elastic-plastic contact force balance is discussed and the regimes where adhesion is important or negligible are pointed out. A comparison of the present results with a previously published approximate elastic-plastic model shows substantial differences in the local separation and in the adhesion force.     

On Isotropic Points in K2SO4 Impurity Crystals

Optics and Spectroscopy - The temperature, spectral and baric dependences of birefringence Δni of potassium sulfate crystals doped with 1.7% of copper are studied. It is established that the...     

On quadratic scalarization of vector optimization problems in Banach spaces

We study vector optimization problems in partially ordered Banach spaces and suppose that the objective mapping possesses a weakened property of lower semicontinuity and make no assumptions on the interior of the ordering cone. We discuss the so-called adaptive scalarization of such problems and show that the corresponding scalar non-linear optimization problems can be by-turn approximated by quadratic minimization problems.     

Peculiarities in the electron spectrum of superconducting laves phase ZrxHf1−xV2

Structurally unstable superconducting Laves phases Zr_xHf_1?xV₂ were investigated in the temperature range 4.2 – 300 K for temperature dependence of magnetic susceptibilities χ, resistivity ρ, and X-ray fluorescent emission 2K-spectra of vanadium. Anomalous dependences χ and ρ as compared to common metals was discovered below 150 K. This may be explained in terms of a phase transition of Peierl's type when the lattice instability results from the instability of the electron spectrum due to the dielectric slit that appears on flat parts of the Fermi surface. The presence of regions with localised electron density in the Laves phases on the low-energy side of the vanadium emission spectrum at low temperatures (T=10K) indicates an essential rebuilding in the electron spectrum of valence electrons.     

Comparing O(N) and SU(N) × SU(N) spin systems in 1 + 1 dimensions to SU(N) gauge theories in 3 + 1 dimensions

We have computed the scale breaking Λ parameters of the euclidean and hamiltonian formulations of the lattice regulated O(N) and SU(N) × SU(N) spin systems in 1 + 1 dimensions in terms of the Λ_PV parameters of the Pauli-Villars regulated continuum models. Using lattice perturbation theory, the renormalized mass gap has been determined in terms of Λ_PV for each model. These results are compared to analogous calculations in SU(N) gauge theories.     

Dielectric half-disk resonator with whispering-gallery modes for measurements of the electric properties of water

We study experimentally the possibility of measuring the dielectric properties of water in the millimeter wavelength range using dielectric resonators excited at the whispering-gallery modes. The influence of various conditions for excitation of such resonators by a local source on the sensitivity and resolution of the performed measurements is shown. Electrodynamic characteristics of the dielectric resonator as a cell for measurements of the electric properties of water are studied. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 9, pp. 769–776, September 2008.