Derivation of the particle dynamics from kinetic equations

We consider the microscopic solutions of the Boltzmann-Enskog equation discovered by Bogolyubov. The fact that the time-irreversible kinetic equation has time-reversible microscopic solutions is rather surprising. We analyze this paradox and show that the reversibility or irreversibility property of the Boltzmann-Enskog equation depends on the considered class of solutions. If the considered solutions have the form of sums of delta-functions, then the equation is reversible. If the considered solutions belong to the class of continuously differentiable functions, then the equation is irreversible. Also, we construct the so called approximate microscopic solutions. These solutions are continuously differentiable and they are reversible on bounded time intervals. This analysis suggests a way to reconcile the time-irreversible kinetic equations with the time-reversible particle dynamics. Usually one tries to derive the kinetic equations from the particle dynamics. On the contrary, we postulate the Boltzmann-Enskog equation or another kinetic equation and treat their microscopic solutions as the particle dynamics. So, instead of the derivation of the kinetic equations from the microdynamics we suggest a kind of derivation of the microdynamics from the kinetic equations.Comment: 18 pages; some misprints have been corrected, some references have been adde

Simulation of non-stationary processes in centrifugal cascades

The model of nonstationary hydraulic and dividing processes in rectangular symmetrical counterstream centrifugal cascades is considered. The calculation technique of centrifugal cascade parameters of transition processes has been developed. The results of numerical computation are presented

Finger patterns produced by thermomagnetic instability in superconductors

A linear analysis of thermal diffusion and Maxwell equations is applied to study the thermomagnetic instability in a type-II superconducting slab. It is shown that the instability can lead to formation of spatially nonuniform distributions of magnetic field and temperature. The distributions acquire a finger structure with fingers perpendicular to the screening current direction. We derive the criterion for the instability, and estimate its build-up time and characteristic finger width. The fingering instability emerges when the background electric field is larger than a threshold field, $E>E_c$, and the applied magnetic field exceeds a value $H_fing \propto 1/\sqrt{E}$. Numerical simulations support the analytical results, and allow to follow the development of the fingering instability beyond the linear regime. The fingering instability may be responsible for the nucleation of dendritic flux patterns observed in superconducting films using magneto-optical imaging.Comment: 8 pages, 6 figures, accepted to Phys. Rev. B; (new version: minor changes

Joule heating effects on quartz particle melting in high-temperature silicate melt

This work is mostly focused on the melting process model simulation of quartz particles having the radius within the range of 10{-6}-10{-3} m. The melting process is simulated accounting for the heat generation at an electric current passage through a quartz particle

Therapy for epilepsy in women: Additional sanogenetic effect caused by the intake of topiramate

Objective: to investigate the efficacy/tolerability of topiramate in reproductive-aged women.Subjects and methods. A group of 58 patients in fertile age (18–35 years) with a long history of focal (n=44) or idiopathic generalized (n=14) epilepsy (FE and IGE) who received mainly combined therapy with 2 antiepileptic drugs (AEDs) was analyzed. 82.8% of the patients were overweight; 51.7% had one or other menstrual cycle disorders; however, the women had been followed up by a gynecologist in exceptional cases.Results. Switch from one of the parent AEDs to topiramate or its incorporation into a treatment regimen as an additional drug substantially improved the course of the disease: remission at 12 months was achieved in 59.1% of the patients with FE and 78.6% of those with IGE. 29.3% of the patients receiving dual therapy, the second medication of which was topiramate, were observed to have lost weight not only if those had high baseline body mass index (BMI), but also if those had normal BMI at baseline. 8.6% of all the patients and 16.7% of those with menstrual cycle disorder achieved normalization of menstrual function. Topiramate was discontinued only in 1 (1.7%) patient because of critical weight loss (BMI<15). In addition to substantial improvement, topiramate used in mono- or dual therapy for FE and IGE may normalize weight and a menstrual cycle. Menstrual function is indicated to be monitored in epileptic women

Plasma treatment of heat-resistant materials

Refractory lining of thermal generating units is exposed to chemical, thermal, andmechanical attacks. The degree of fracture of heat-resistant materials depends on the chemicalmedium composition, the process temperature and the material porosity. As is known, a shorttermexposure of the surface to low-temperature plasma (LTP) makes possible to createspecific coatings that can improve the properties of workpieces. The aim of this work is toproduce the protective coating on heat-resistant chamotte products using the LTP technique.Experiments have shown that plasma treatment of chamotte products modifies the surface, anda glass-ceramic coating enriched in mullite is formed providing the improvement of heatresistance. For increasing heat resistance of chamotte refractories, pastes comprising mixturesof Bacor, alumina oxide, and chamot were applied to their surfaces in different ratios. It isproved that the appropriate coating cannot be created if only one of heat-resistant componentsis used. The required coatings that can be used and recommended for practical applications areobtained only with the introduction of powder chamot. The paste composition of 50% chamot,25% Bacor, and 25% alumina oxide exposed to plasma treatment, has demonstrated the mostuniform surface fusion