дифузія

This article presents the results of studies of the structure of the emulsion formed in the wastewater of edible oil production. The process of refining edible oils produces stable emulsions that are released into wastewater and pose a threat to the hydrosphere.  The main pollutants in these wastewaters are organic substances, mainly of a fatty nature, which existing wastewater treatment plants are unable to treat to the level of sanitary requirements. This creates a significant environmental problem as it causes pollution of surface waters with organic substances.

Modeling of the impurity diffusion process in a layer under the action of a system of random point sources is carried out.  Mass sources of different power are uniformly distributed in a certain internal interval, that may also coincide with the entire region of the layer.  The statistics of random sources is given.  The solution of the initial-boundary value problem is found as the sum of the homogeneous problem solution and the convolution of the Green's function with the system of the random point sources.  Averaging of the solution is performed on the internal subinterval and in the ent

The purpose of this research is to suggest and analyze a spatiotemporal of an IS-LM model with two delays, interest rate, liquidity preference and general investment function.  The first delay into the proposed model refers to the time delay between the decision of investment and his implementation.  However, the second one represents the delay in investment production.  The well posedness of the model is proved.  The stability analysis and the existence of Hopf bifurcation are obtained.  Furthermore, numerical examples that confirm the analytical results are shown.

The migration of highly concentrated pesticide solutions in the soil has been experimentally studied. A mathematical model of the diffusion process in the soil environment has been developed. Based on the mathematical model, a system of equations for calculating the duration and intensity of the process depending on environmental parameters was obtained. The dependence of the process velocity on the direction of the diffusion front is determined, and the diffusion coefficients, kinetic coefficients of the diffusion process and the diffusion front velocity were calculated.

In this paper, we investigate the population dynamics of phytoplankton–zooplankton–nanoparticle model with diffusion and density dependent death rate of predator.  The functional response of predator in this model is considered as Beddington–DeAngelis type.  The stability analysis of the equilibrium points is observed by applying the Routh–Hurwitz criterion.  Numerical simulations are given to illustrate the theoretical results.

Розглянуто  процес  насичення  цукрозою  частинок  плодів  гарбуза.  Розроблено експериментальну  установку  насичення  частинок  плодів  цукром  в  умовах  інтенсивного пневматичного перемішування. Отримані кінетичні залежності насичення цукатів  та зміни концентрації  цукрового  сиропу  за  різних  температур.  Проведене  порівняння  умов  наси- чення за різних співвідношень “цукат : сироп”. Математичним узагальненням підтверджено обране  авторами  статті  співвідношення  “цукат :  сироп”.