Long-term sealing loss of hydraulic bearings

The factors responsible for the loss of sealing of hydraulic bearings in long-term operation are considered. The appearance of cavitation zones in the working fluid of hydraulic bearings and microscopic hydraulic bearings is explained.     

Aerothermochemical destruction of silicon carbide washed by a high-temperature flow of air

A new approach for calculating the rate of aerothermochemical destruction of silicon carbide that is washed by an oxidative gas flow under conditions of long heating of the substance to relatively low temperatures is proposed. Possible physical reasons are established, which allows one to explain the anomalous dependence of the destruction of silicon carbide on pressure that is experimentally observed.     

Damping characteristics of cable-based dampers and hydraulic bearings

The spectral characteristics of hydraulic bearings and cable-based dampers are presented. In hydraulic bearings, the energy is absorbed by a rheological medium; in cable-based vibrational dampers, by contrast, the energy is absorbed by the dry friction of individual elastic wires within the strands of a steel cable system. In both cases, the experimental conditions are exactly the same. With the same spectra of the input vibrations, the output spectra are found to be considerably different.     

Power Characteristics and Temperature Dependence of the Angular Beam Divergence of Lasers with a Near-Surface Active Region

Results are presented of a study of light–current characteristics and far-field patterns of emission of stripe lasers with coupled planar waveguides. This configuration makes it possible to suppress the generation of excited modes and to have a small (about 0.9 μm) depth of the active region from the surface of the laser crystal. A high-temperature stability of the angular emission divergence (34.0° ± 1.5°) in the temperature range 20–80°C is demonstrated. The largest value of the output power is limited to 12.2 W in the continuous-wave mode by the catastrophic mirror damage.     

Fabrication and buckling dynamics of nanoneedle AFM probes

A new method for the fabrication of high-aspect-ratio probes by electron beam induced deposition is described. This technique allows the fabrication of cylindrical 'nanoneedle' structures on the atomic force microscope (AFM) probe tip which can be used for accurate imaging of surfaces with high steep features. Scanning electron microscope (SEM) imaging showed that needles with diameters in the range of 18-100?nm could be obtained by this technique. The needles were shown to undergo buckling deformation under large tip-sample forces. The deformation was observed to recover elastically under vertical deformations of up to ～ 60% of the needle length, preventing damage to the needle. A technique of stabilizing the needle against buckling by coating it with additional electron beam deposited carbon was also investigated; it was shown that coated needles of 75?nm or greater total diameter did not buckle even under tip-sample forces of ～ 1.5?μN.     

Dynamic Transitions within the Vortex Solid of YBa2Cu3Oy Single Crystals

Transport measurements on YBa ₂ Cu ₃ O _y have revealed strong history dependences in pinning properties of the vortex solid. By using an annealing current to control exposure of the vortex system to the disorder potential, we were able to study the development of such hysteretic responses, across the region of the vortex freezing transition. We have explained the observed behaviour in terms of coexistent vortex liquid and solid phases.     

A method for solving a problem of possibilistic programming

The models of possibilistic programming considered in [1–3] are generalized to the case when the binary relations that relate the left and right sides in the model of constraints are fuzzy. The corresponding mathematical formalism for describing models of this class is developed. A method for solving the problem is proposed. The capabilities of the approach are demonstrated in numerical examples.