Associated φΛ0 production in the EXCHARM experiment

The features of the associated production of φ mesons with Λ⁰ hyperons in neutron-carbon interactions were investigated. The experiment was performed with the aid of the EXCHARM spectrometer at the Serpukhov accelerator in a neutron beam of energy in the interval 20–70 GeV. The differential cross section for inclusive associated φΛ⁰ production was measured.     

Associated production of ϕ mesons and neutral kaons in the EXCHARM experiment

The features of the associated production of ? mesons and neutral kaons are studied on the basis of data obtained at the EXCHARM spectrometer (Serpukhov accelerator) in neutron—carbon interactions at neutron-beam energies in the range 20–70 GeV. The cross section for the inclusive associated production of ? and K ⁰/-K ⁰ is obtained. The fraction of processes allowed by the Okubo-Zweig-Iizuka rule is estimated in the reactions of ?-meson inclusive production.     

Nonequilibrium processes at the shock wave front in inert gases with a small amount of Fe(CO)<Subscript>5</Subscript> impurity

Nonequilibrium processes occurring in shock waves generated in argon and helium containing a small amount of Fe(CO)₅ impurity are investigated experimentally and numerically. Nonequilibrium radiation peaks are found in the relaxation zone of the shock wave, and a dependence of the radiation intensity on the shock parameters and Fe(CO)₅ concentration is obtained. Unresolved spectra of the resulting radiation in the range 400–700 nm are recorded. It is shown that the effects observed cannot be accounted for by high-energy collisions in the zone of shock translational relaxation. It is concluded that these nonequilibrium phenomena are related to electronic excitation of small iron clusters at fast condensation of supersaturated iron vapor arising due to Fe(CO)₅ decomposition. A kinetic model describing the formation of excited clusters is suggested.     

Ultrasound measurements of cavitation bubble radius for femtosecond laser-induced breakdown in water

A recently developed ultrasound technique is evaluated by measuring the behavior of a cavitation bubble that is induced in water by a femtosecond laser pulse. The passive acoustic emission during optical breakdown is used to estimate the location of the cavitation bubble's origin. In turn, the position of the bubble wall is defined based on the active ultrasonic pulse-echo signal. The results suggest that the developed ultrasound technique can be used for quantitative measurements of femtosecond laser-induced microbubbles.     

Experimental study of carbon particle charging at shock-wave pyrolysis of C3O2

The temporal variation in electron and ion concentrations have been measured in shock-heated mixtures of Ar + (0-2)% C₃O₂ in the 2000-3600 K temperature and 15-30 bar pressure range. Experiments in pure argon proved that the observed free electrons and ions originate from inherent impurities of sodium. The equilibrium concentrations of free charges in argon were established during (1-3) × 10⁻⁵ s and varied from 4 × 10¹¹ cm⁻³ at T₅ = 2500 K to 5 × 10¹² cm⁻³ at 3500 K. In the reactive mixtures, containing C₃O₂, the time profiles of electron and ion concentrations showed a more complicate behavior—a fast rise to a maximum followed by a gradual decay. The maximum ion concentrations were much higher and electron concentrations were much lower than in similar conditions in argon. The extent of the subsequent decay of electron concentration increased proportionally to the square of the C₃O₂ concentration. In the mixture with 2% C₃O₂ the final electron concentration was about 100 times less than in pure argon. The characteristic decay time of free charges varied from 400 to 40 μs and decreased proportionally to the square root of the charge concentration. The data analysis is based on the assumption that the observed redistribution of electron and ion concentrations is caused by charging of the carbon particles formed during pyrolysis of C₃O₂. The kinetics of particle charging and the final distribution of charges were evaluated by the analysis of electron and ion fluxes to the particles in accordance with the electric potentials of charged particles and corresponding sodium ionization. A predominance of negatively charged particles, caused by the high electron mobility, resulted in their much higher concentration than the concentration of free electrons.     

Influence of quantum effects on the initiation of ignition and detonation

A theoretical analysis that allows one to quantify the quantum corrections to the rate constants of endothermic reactions associated with an increase in the high-energy tails of the momentum distribution functions at high pressures due to a manifestation of the uncertainty principle for the energy of the colliding particles at a high collision frequency is performed. The initiation of ignition of hydrogen-oxygen mixtures is investigated and special series of experiments on the initiation of detonation waves of condensation in carbon suboxide and acetylene at elevated pressures near the low-temperature limits have been carried out. The experimentally observed deviations in the Arrhenius dependences of the induction periods of the initiation of hydrogen ignition and detonation waves of condensation are shown to be well described by the proposed quantum corrections.     

Estimation of shear wave velocity in gelatin phantoms utilizing PhS-SSOCT

We report a method for measuring shear wave velocity in soft materials using phase stabilized swept source optical coherence tomography (PhS-SSOCT). Wave velocity was measured in phantoms with various concentrations of gelatin and therefore different stiffness. Mechanical waves of small amplitudes (??10 ??m) were induced by applying local mechanical excitation at the surface of the phantom. Using the phase-resolved method for displacement measurement described here, the wave velocity was measured at various spatially distributed points on the surface of the tissue-mimicking gelatin-based phantom. The measurements confirmed an anticipated increase in the shear wave velocity with an increase in the gelatin concentrations. Therefore, by combining the velocity measurements with previously reported measurements of the wave amplitude, viscoelastic mechanical properties of the tissue such as cornea and lens could potentially be measured.     

Dielectric losses in submicrometer barium titanate near the Curie temperature

Low-frequency dielectric losses (tanδ) in barium titanate ceramics with crystallite sizes of ~100 nm near the Curie temperature are studied. It is shown that the observed tanδ maximum is described by a low-frequency fluctuation mechanism of dielectric losses. An analysis of experimental data shows that the critical nucleus size in ultrafine material is smaller than the one in bulk barium titanate.     

Application of Information Technologies and Programming Methods of Embedded Systems for Complex Intellectual Analysis

An information model is outlined, which represents an intelligent system of metallographic analysis in the form of a set of subsystems, the interaction of which ensures the performance of metallographic analysis functions. The structure of the information storage subsystem for metallographic analysis is presented. The deployment model of an intelligent metallographic analysis system is proposed and described. The paper outlines the approach to the presentation of an expert subsystem for metallographic quality control of metals based on a neural network. The process of finding a close precedent in metallographic analysis with reference to a multilayer neural network is described. An intelligent metallographic analysis system is described, which based on proposed information model. A specialized software of an intelligent metallographic analysis system is presented. The functioning results of the developed system for processing images of steel microstructures to determine the steel quantitative parameters is presented.