Structural changes of the friction surface and wear resistance of a ZrO2-Y2O3 ceramic

Quantitative parameters of the surface structures and the wear resistance of a ZrO₂-Y₂O₃ ceramic tested by friction on a steal disk have been determined. It is shown that the friction contact gives rise to quasiperiodic cracks on the friction surface of the ceramic and leads to the formation of a transfer layer. It is established that the wear intensity correlates with the intercrack spacing along the sliding direction and the amount of the steel counterbody elements on the ceramic surface.     

Thin-Layer Electrochemically Produced SiO<Subscript>2</Subscript>/Ni Composites in a Prototyping Lithium-Ion Battery

Silicon dioxide has been produced by deposition from an aqueous solution of Na₂SiО₃ · mH₂O. The particle size of the main faction of the synthesized material determined using an electron microscope ranges from 12 to 16 nm. According to XRD phase analysis, an amorphous modification of silicon dioxide has been obtained. It was then used to synthesize a thin-layer SiO₂/Ni composite via electrolysis to determine the possibility of using it in the negative electrodes of miniature LIBs (LIBs). Studies of the SiO₂/Ni composite in a prototyping lithium-ion battery in the galvanostatic mode have shown stable cycling in the voltage range from 0.40 to 0.15 V indicating promising usage in LIBs.     

Structural and phase binder state and behavior during friction of WC-(Fe-Mn-C) composites

The work presents results of analysis of the structure of the tribosurfaces and triboengineering characteristics of two composite materials WC-(Fe-Mn-C) with different structural and phase binder state after sliding on a steel disk within the range of velocities from 1 to 4 m/s under pressure 5 MPa. It is shown that the wear rate of the material heterophase binder structure containing fine crystalline granular austenite and a significant portion of tempered martensite in the original state exceeds at slower velocities (1 m/s) 3.5 times that of the composite with the austenite binder. As the velocity grows to 4 m/s, the wear resistance of these two materials approach and then nearly coincide. In the process of friction at all sliding velocities, the binders of both composites undergo γ → α-transformation, the extent and depth of which are governed by the acceleration.     

Features of high-speed wear of WC-steel 11G13 material in contact with cast tool steel

The tribological behavior of WC-steel 11G13 composite material in contact with cast tool steel is considered over a sliding speed range of 10–40 m/s under a pressure of 2 MPa. The after-test surface structure is examined. Catastrophic wear of the material is proved to occur within a 23–30 m/s sliding speed range. It is shown that the sharp (fourfold) increase in the wear rate within the given speed range is related to a change in the wear mode. The subsurface region of the WC-steel 11G13 material is found to have a multilayer structure, the layers differing greatly in their properties and structure.     

Nonstationary vibrations of robot construction elements made of composite materials

The effect of damping on nonstationary vibrations of elements of manipulators and mechanisms with flexible links is considered. To analyze nonstationary vibrations in the case of kinematic excitation, a finite-element frequency method was employed, which is based on numerical integral Fourier transformation.     

Estimate of the Stress State of Rocks in the Vicinity of Gas-Condensate Field on the Sea Shelf

The boundary-element method is used for studying the stress state of rocks in the vicinity of the extensive cavity with gas depending on the actual gravitational and tectonic forces, gas pressure, as well as deposit geometry. The pressure value, up to which the field can be developed safely, is estimated; the possible mechanisms of enclosing mass deformation are examined.     

Phonetic encoding method in the isolated words recognition problem

A phonetic approach to the problem of automatic recognition of isolated words is investigated. The phonetic encoding method whereby each word from a vocabulary is associated with the code sequence of stable phonemes is proposed. The information-theoretical estimate of vocabulary confusability, the calculations of which rely on the phonetic database of a speaker and the communications channel SNR, is synthesized using the Kullback-Leibler divergence properties. In the experimental study of the proposed method, the mutual influence between the recognition quality and the proposed estimate of confusability is demonstrated by solving the problem of recognition of words in the Russian speech. It is established that the introduced requirement to isolated syllable pronunciation makes it possible to attain the 90–95% accuracy of recognition for vocabularies containing 2000 words.     

Relative Conversion of Lower Alkanes in Their Simultaneous Partial Gas-Phase Oxidation

Experimental and theoretical studies are undertaken to analyze the relative conversions of methane and ethane in their simultaneous partial oxidation and also the conversions of C₁–C₄ hydrocarbons in the oxidation of more complex mixtures that model real natural and associated gases. It is shown that, under the conditions at which C₁–C₄ hydrocarbons are oxidized to oxygenates and at an initial oxygen concentration of 4–16%, the rapid burnout of higher hydrocarbons is accompanied by an increase in the concentration of methane produced by their oxidative reforming.     

Residual oil pockets and their stimulation in productive formations

The article analyzes processes running in an oil pool under contour water flooding and resulting in formation of bypassed oil. Based on stability criteria, the authors discuss destabilization of the residual oil pockets by vibration so that the bypassed oil becomes proved & developed.