Second Order Stochastic Partial Integro Differential Equations with Delay and Impulses

© Published under licence by IOP Publishing Ltd. The aerosol movement at an open end of a pipe at the resonant frequency was experimentally studied. The aerosol flow in an external wave field was visualized. The numerical value of the Rayleigh correction for an open end of an experimental plant was obtained. A good agreement between the numerical and experimental values was demonstrated

Solution of Nonhomogeneous Helmholtz Equation with Variable Coefficient Using Boundary Domain Integral Method

© 2018, Pleiades Publishing, Ltd. The Boundary Domain Integral Method (BDIM) is applied to the solution of the nonhomogeneous Helmholtz equation with variable coefficient. The analytical formulas for the integrals over the individual boundaries and domain integrals are used to increase the accuracy of the numerical approach. Comparisons of the developed BDIM with the analytical solutions for the homogeneous Helmholtz equation with constant coefficient and the nonhomogeneous Helmholtz equation with variable coefficient are given

A theoretical study of aerosol sampling by an idealized spherical sampler in calm air

The performance of an idealized spherical sampler operating in calm air for an inlet arbitrarily oriented relative to the gravity force is studied theoretically. Under potential flow assumption the air velocity field is obtained by using a model of a finite-size sink on a sphere. The particle motion equations are solved to find the limiting trajectory surface and to calculate the aspiration efficiency. The singular points of the motion equations as a function of settling velocity of particles and the sampler orientation angle are investigated. The connection between the pattern of typical zones of particle trajectories around the sampler and the location of the singular points is illustrated. The effects of partial sampling from zones without particles and of particle screening are discussed. The results of parametrical investigations of the dependence of the aspiration efficiency on the Stokes number and their analysis are presented. In the case of vertically upwards orientation of the sampler the proposed mathematical model gives fair agreement with experimental data from the work by Su and Vincent (Abstracts of sixth international aerosol conference, Taipei, Taiwan, 2002a, pp. 639-640). © 2003 Elsevier Ltd. All rights reserved

Oscillations of a homogeneous gas and drift particles in an external wave field an open tube

© Published under licence by IOP Publishing Ltd. The dynamics of a particle and a homogeneous gas in the external wave field open tube by different values of amplitude of piston travel at the first eigenfrequencies in the shock- free mode are experimentally investigated. It is found the velocity distribution of the gas flow in the external the wave field open tube in different cross sections at various amplitudes of piston travel. The dependence of the coordinates of the particle along the axis the outside of the tube at on the time at resonance frequency are obtained. The comparison of velocity flow of the gas and particle drift in the external the wave field open tube is performed

Investigation of the equilibrium establishment in the spin system by using dipole magic echo

An experimental and theoretical investigation of the equilibrium establishment in an isolated spin system is performed. The "time-reversion" effects were used at the experiments. Comparison of the description of the experimental results obtained on the basis of reversible equations of mechanics and nonequilibrium thermodynamics is carried out. It is demonstrated that the equations of mechanics do not describe the spin macrosystem transition to the equilibrium. The experimental results correspond to the theory which is based on the nonequilibrium thermodynamics methods and takes into account the quick decay of cross-correlations in the systems. © Springer-Verlag 1999

Solution of stokes flow problem using biharmonic equation formulation and multiquadrics method

© 2016, Pleiades Publishing, Ltd.The biharmonic equation formulation of the Stokes flow problem for multiquadrics method is developed. The main advantage of the approach is the iteration free method to find the solution. The numerical method is applied for the problem of steady incompressible fluid flow past a cylinder in the periodic cell of the Kuwabara model. The comparison with known analytical solution and the analysis of absolute and relative errors show that proposed approach gives satisfactory accuracy. The nonmonotonic dependence of the relative errors on the shape parameter typical for multiquadrics method is observed

Application of ESEEM to study the structure of free radicals

Manifestations of the hyperfine interaction of paramagnetic particles in their electron spin echo signal decay were comprehensively discussed. Mechanochemically activated calcium gluconate was studied using electron spin echo modulation phenomenon and electron-nuclear double resonance techniques and quantum-chemical calculations. Three possible structures are obtained for free radicals in calcium gluconate. To specify the structure of radicals, further investigations are needed. © 2008 Springer

Spherical particle dynamics at oscillations in tubes in the shock wave field

© 2016, Pleiades Publishing, Ltd.The behavior of spherical particles with various geometric and physical parameters is experimentally investigated at the stimulated longitudinal gas oscillations in closed and opened tubes as well as in the external wave field near subharmonic resonances. The temporal dependences of the oscillating particle coordinate are obtained for different tube lengths and excitement frequencies. It is shown that, inside the tube, a particle moves, performing the longitudinal oscillations, from the opened end to the piston. Outside the tube, a particle moves from the opened end to the external wave field, without oscillations and with nonlinear coordinate increase in time. Also investigated is the influence of the particle weight and diameter and of the gas excitement frequency on the oscillation amplitude of the particle and its average velocity. The nonmonotone character revealed the dependence of the average velocity of the spherical particle on the gaseous column oscillation frequency at passing through the subharmonic resonance frequencies

Experimental studies of resonant nonlinear oscillations of a gas in an open and closed tube

© 2018 Institute of Physics Publishing. All rights reserved. Nonlinear oscillations of gas in an open and closed tube were researched experimentally. Dependencies of the of the pressure oscillation amplitude were obtained at the resonance frequencies of the gas excitation at a fixed amplitude of the tube displacement