Construction of a numerical model and algorithm for solving two-dimensional problems of filtration of multicomponent liquids, taking into account the moving “oil-water” interface

The paper considers a two-dimensional mathematical model of the filtration of a viscous, incompressible fluid in a deformable porous medium. The article describes a mathematical model of the problem at the “oil-water” interface with a system of parabolic differential equations. The problem posed is solved numerically using the differential-difference method based on the longitudinal-transverse scheme and the differential sweep method to determine the unknown boundary. To obtain a differential-difference problem, an algorithmic representation of a hidden scheme of alternating directions (longitudinal-transverse scheme) is used. The resulting system of differential-difference equations with initial conditions is known for each time layer along straight lines along the x axis, and then along each y axis it is solved by a differential sweep along a straight line, where the values just found correspond to time, i.e., the layer is taken as initial conditions. By approximating the differential equations in time, the position of the interface is determined for each time layer

Theoretical and practical meaning of ecological morphophysiological research og fish reproduction in the reservoir with ecology changed conditions

Fish reproduction research showed that the change of existence conditions changes the character of sexual cell growth changes. Evident changes in the duration of protoplasmatic growth are observed as well as the asynchronism degree of sexual cells and their development rate during annual period

The peculiarities offish sex cycles and their ovary ripeness stages

All the ovogenesis and sex cycles peculiarities of the studied fishes are species-specific with biology particularity of different fishes including their reproductions. The research showed that the changes caused by different anthropogenic factors often change the whole process of gametogenesis thereby the character and fish reproduction intensity in the ecologically changed conditions

THERMOELECTRIC SYSTEM FOR EXTRACTION OF FOREIGN OBJECTS FROM HUMAN BODY

Objectives. The purpose of the article is to examine the design of the thermoelectric system (TPP) for the extraction of foreign objects from the human body by the method of freezing, as well as the simulation of heat transfer processes in it.Method. A design and a physical model of the system for the extraction of foreign objects from the human body are proposed, in which the source of cold is a thermoelectric module (TEM) placed on a special mechanical device made in the form of a probe, which also provides removal of heat from the hot junctions of the module. A mathematical model of thermal power plants was developed, implemented on the basis of solving the problem of ice layer growth using the method of solving the non-stationary Fourier differential equation, presented in partial derivatives by reducing it to an equation with full derivatives based on the use of an extended version of the Lame-Clapeyron substitution, and power series, which describes the temperature distribution in the frozen ice layer and satisfies the boundary conditions of the problem.Result. Data were obtained on the change in temperature of the extracted object and the thickness of the ice layer over time at various values of the cooling capacity of TEM. It is established that the duration of the formation of an ice layer between the object to be extracted and the cold surface of the TEM, which is the executive element of the system, is within narrow limits that meet medical standards, while the speed of the ice growth process depends on its thickness (increasing the cooling capacity of the TEM from 1000 to 3000 W / m2 reduces the duration of the formation of an ice layer, 2 mm thick, by almost 40 s, while the temperature of the extracted object decreases from 269 K to 252 K). It is indicated that the selection of geometric parameters of TEM and its power supply should focus on the limitations on the operation of the device, as well as medical norms and standards in order to avoid the process of frostbite of the adjacent tissues.Conclusion. A method is proposed for increasing the efficiency of the system, according to which the preliminary cooling of the TPP by an external source of cold is used, as well as the use of forced TEM operation modes

Structural Studies of dielectric HDPE+ZrO2 polymer nanocomposites: filler concentration dependences

International audienceStructural properties of HDPE+ZrO2 polymer nanocomposites thin films of 80-100 mu m thicknesses were investigated using SANS, XRD, Laser Raman and FTIR spectroscopy. The mass fraction of the filler was 1, 3, 10, and 20%. Results of XRD analysis showed that ZrO2 powder was crystallized both in monoclinic and in cubic phase under normal conditions. The percentages of monoclinic and cubic phase were found to be 99.8% and 0.2%, respectively. It was found that ZrO2 nanoparticles did not affect the main crystal and chemical structure of HDPE, but the degree of crystallinity of the polymer decreases with increasing concentration of zirconium oxide. SANS experiments showed that at ambient conditions ZrO2 nanoparticles mainly distributed like mono-particles in the polymer matrix at all concentrations of filler. The structure of HDPE+ZrO2 does not changes up to 132 degrees C at 1-3% of filler, excepting changing of the polymer structure at temperatures upper 82 degrees C. At high concentrations of filler 10-20% the aggregation of ZrO2 nanoparticles occurs, forming domains of 2.5 mu m. The results of Raman and FTIR spectroscopy did not show additional specific chemical bonds between the filler and the polymer matrix. New peaks formation was not observed. These results suggest that core-shell structure does not exist in the polymer nanocomposite system

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

Herein, we investigated the influence of two types of nanoparticle fillers, i.e., amorphous SiO2 and crystalline ZrO2, on the structural properties of their nanocomposites with high-density polyethylene (HDPE). The composite films were prepared by melt-blending with a filler content that varied from 1% to 20% v/v. The composites were characterized by small- and wide-angle x-ray scattering (SAXS and WAXS), small-angle neutron scattering (SANS), Raman spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). For both fillers, the nanoaggregates were evenly distributed in the polymer matrix and their initial state in the powders determined their surface roughness and fractal character. In the case of the nano-ZrO2 filler, the lamellar thickness and crystallinity degree remain unchanged over a broad range of filler concentrations. SANS and SEM investigation showed poor interfacial adhesion and the presence of voids in the interfacial region. Temperature-programmed SANS investigations showed that at elevated temperatures, these voids become filled due to the flipping motions of polymer chains. The effect was accompanied by a partial aggregation of the filler. For nano-SiO2 filler, the lamellar thickness and the degree of crystallinity increased with increasing the filler loading. SAXS measurements show that the ordering of the lamellae is disrupted even at a filler content of only a few percent. SEM images confirmed good interfacial adhesion and integrity of the SiO2/HDPE composite. This markedly different impact of both fillers on the composite structure is discussed in terms of nanoparticle surface properties and their affinity to the HDPE matrix