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The paper presents a physico-mathematical model of the perturbed region formed in the lower D-layer of the ionosphere under the action of directed radio emission flux from a terrestrial stand of the megahertz frequency range, obtained as a result of comprehensive theoretical studies. The model is based on the consideration of a wide range of kinetic processes taking into account their nonequilibrium and in the two-temperature approximation for describing the transformation of the radio beam energy absorbed by electrons. The initial data on radio emission achieved by the most powerful radio-heating stands are taken in the paper. Their basic characteristics and principles of functioning, and features of the altitude distribution of the absorbed electromagnetic energy of the radio beam are briefly described. The paper presents the decisive role of the D-layer of the ionosphere in the absorption of the energy of the radio beam. On the basis of theoretical analysis, analytical expressions are obtained for the contribution of various inelastic processes to the distribution of the absorbed energy, which makes it possible to correctly describe the contribution of each of the processes considered. The work considers more than 60 components. The change of the component concentration describe about 160 reactions. All the reactions are divided into five groups according to their physical content: ionization-chemical block, excitation block of metastable electronic states, cluster block, excitation block of vibrational states and block of impurities. Blocks are interrelated and can be calculated both jointly and separately. The paper presents the behavior of the parameters of the perturbed region in daytime and nighttime conditions is significantly different at the same radio flux density: under day conditions, the maximum electron concentration and temperature are at an altitude of ~45–55 km; in night ~80 km, with the temperature of heavy particles rapidly increasing, which leads to the occurrence of a gas-dynamic flow. Therefore, a special numerical algorithm are developed to solve two basic problems: kinetic and gas dynamic. Based on the altitude and temporal behavior of concentrations and temperatures, the algorithm makes it possible to determine the ionization and emission of the ionosphere in the visible and infrared spectral range, which makes it possible to evaluate the influence of the perturbed region on radio engineering and optoelectronic devices used in space technology.

Experimental, theoretical and numerical investigations of equatorial spread F, equatorial plasma bubbles (EPBs), plasma depletion shells, and plasma clouds are continued at new variety articles. Nonlinear growth, bifurcation, pinching, atomic and molecular ion dynamics are considered at there articles. But the authors of this article believe that not all parameters of EPB development are correct. For example, EPB bifurcation is highly questionable.

A maximum speed inside EPBs and a development time of EPB are defined and studied. EPBs starting from one, two or three zones of the increased density (initial plasma clouds). The development mechanism of EPB is the Rayleigh-Taylor instability (RTI). Time of the initial stage of EPB development went into EPB favorable time interval (in this case the increase linear increment is more than zero) and is 3000–7000 c for the Earth equatorial ionosphere.

Numerous computing experiments were conducted with use of the original two-dimensional mathematical and numerical model MI2, similar USA standard model SAMI2. This model MI2 is described in detail. The received results can be used both in other theoretical works and for planning and carrying out natural experiments for generation of F-spread in Earth ionosphere.

Numerical simulating was carried out for the geophysical conditions favorable for EPBs development. Numerical researches confirmed that development time of EPBs from initial irregularities with the increased density is significantly more than development time from zones of the lowered density. It is shown that developed irregularities interact among themselves strongly and not linearly even then when initial plasma clouds are strongly removed from each other. In addition, this interaction is stronger than interaction of EPBs starting from initial irregularities with the decreased density. The numerical experiments results showed the good consent of developed EPB parameters with experimental data and with theoretical researches of other authors.

The two significant geometric parameters are proposed that affect the physical quantities interpolation in the smoothed particle hydrodynamics method (SPH). They are: the smoothing coefficient which the particle size and the smoothing radius are connecting and the volume coefficient which determine correctly the particle mass for a given particles distribution in the medium.

In paper proposes a technique for these parameters influence assessing on the SPH method interpolations accuracy when the hydrostatic problem solving. The analytical functions of the relative error for the density and pressure gradient in the medium are introduced for the accuracy estimate. The relative error functions are dependent on the smoothing factor and the volume factor. Designating a specific interpolation form in SPH method allows the differential form of the relative error functions to the algebraic polynomial form converting. The root of this polynomial gives the smoothing coefficient values that provide the minimum interpolation error for an assigned volume coefficient.

In this work, the derivation and analysis of density and pressure gradient relative errors functions on a sample of popular nuclei with different smoothing radius was carried out. There is no common the smoothing coefficient value for all the considered kernels that provides the minimum error for both SPH interpolations. The nuclei representatives with different smoothing radius are identified which make it possible the smallest errors of SPH interpolations to provide when the hydrostatic problem solving. As well, certain kernels with different smoothing radius was determined which correct interpolation do not allow provide when the hydrostatic problem solving by the SPH method.

The utilization of unmanned aerial vehicles (UAVs) in high-rise firefighting operations is the right solution for reaching the fire scene on high floors quickly and effectively. The article proposes a quadrotor-type firefighting UAV model carrying a launcher to launch a missile containing fire extinguishing powders into a fire. The kinematic model describing the flight kinematics of this UAV model is built based on the Newton – Euler method when the device is in normal motion and at the time of launching a firefighting missile. The results from the simulation testing the validity of the kinematic model and the simulation of the motion of the UAV show that the variation of Euler angles, flight angles, and aerodynamic angles during a flight are within an acceptable range and overload guarantee in flight. The UAV flew to the correct position to launch the required fire-extinguishing ammunition. The results of the research are the basis for building a control system of high-rise firefighting drones in Vietnam.

An approach to numerical analysis of thermo-hydraulic processes proceeding in a fast-neutron reactor is described in the given article. The description covers physical models, numerical schemes and geometry simplifications accepted in the computational model. Steady-state and dynamic regimes of reactor operation are considered. The steady-state regimes simulate the reactor operation at nominal power. The dynamic regimes simulate the shutdown reactor cooling by means of the heat-removal system.

Simulation of thermo-hydraulic processes is carried out in the FlowVision CFD software. A mathematical model describing the coolant flow in the first loop of the fast-neutron reactor was developed on the basis of the available geometrical model. The flow of the working fluid in the reactor simulator is calculated under the assumption that the fluid density does not depend on pressure, with use a $k–\varepsilon$ turbulence model, with use of a model of dispersed medium, and with account of conjugate heat exchange. The model of dispersed medium implemented in the FlowVision software allowed taking into account heat exchange between the heat-exchanger lops. Due to geometric complexity of the core region, the zones occupied by the two heat exchangers were modeled by hydraulic resistances and heat sources.

Numerical simulation of the coolant flow in the FlowVision software enabled obtaining the distributions of temperature, velocity and pressure in the entire computational domain. Using the model of dispersed medium allowed calculation of the temperature distributions in the second loops of the heat exchangers. Besides that, the variation of the coolant temperature along the two thermal probes is determined. The probes were located in the cool and hot chambers of the fast-neutron reactor simulator. Comparative analysis of the numerical and experimental data has shown that the developed mathematical model is correct and, therefore, it can be used for simulation of thermo-hydraulic processes proceeding in fast-neutron reactors with sodium coolant.

The conjugate problem of disk movement into gas-filled volume of the spring-type safety valve is solved. The questions of determining the physically correct value of the disk initial lift are considered. The review of existing approaches and methods for solving of such type problems is conducted. The formulation of the problem about the valve actuation when the vessel pressure rises and the mathematical model of the actuation processes are given. A special attention to the binding of physical subtasks is paid. Used methods, numerical schemes and algorithms are described. The mathematical modeling is performed on basе the fundamental system of differential equations for viscous gas movement with the equation for displacement of disk valve. The solution of this problem in the axe symmetric statement is carried out numerically using the finite volume method. The results obtained by the viscous and inviscid models are compared. In an inviscid formulation this problem is solved using the Godunov scheme, and in a viscous formulation is solved using the Kurganov – Tadmor method. The dependence of the disk displacement on time was obtained and compared with the experimental data. The pressure distribution on the disk surface, velocity profiles in the cross sections of the gap for different disk heights are given. It is shown that a value of initial drive lift it does not affect on the gas flow and valve movement part dynamic. It can significantly reduce the calculation time of the full cycle of valve work. Immediate isotahs for various elevations of the disk are presented. The comparison of jet flow over critical section is given. The data carried out by two numerical experiments are well correlated with each other. So, the inviscid model can be applied to the numerical modeling of the safety valve dynamic.

The paper contains numerical simulation of nonisothermal nonlinear flow in a porous medium. Twodimensional unsteady problem of heavy oil, water and steam flow is considered. Oil phase consists of two pseudocomponents: light and heavy fractions, which like the water component, can vaporize. Oil exhibits viscoplastic rheology, its filtration does not obey Darcy's classical linear law. Simulation considers not only the dependence of fluids density and viscosity on temperature, but also improvement of oil rheological properties with temperature increasing.

To solve this problem numerically we use streamline method with splitting by physical processes, which consists in separating the convective heat transfer directed along filtration from thermal conductivity and gravitation. The article proposes a new approach to streamline methods application, which allows correctly simulate nonlinear flow problems with temperature-dependent rheology. The core of this algorithm is to consider the integration process as a set of quasi-equilibrium states that are results of solving system on a global grid. Between these states system solved on a streamline grid. Usage of the streamline method allows not only to accelerate calculations, but also to obtain a physically reliable solution, since integration takes place on a grid that coincides with the fluid flow direction.

In addition to the streamline method, the paper presents an algorithm for nonsmooth coefficients accounting, which arise during simulation of viscoplastic oil flow. Applying this algorithm allows keeping sufficiently large time steps and does not change the physical structure of the solution.

Obtained results are compared with known analytical solutions, as well as with the results of commercial package simulation. The analysis of convergence tests on the number of streamlines, as well as on different streamlines grids, justifies the applicability of the proposed algorithm. In addition, the reduction of calculation time in comparison with traditional methods demonstrates practical significance of the approach.

The work continues research on the ability of a person to improve the productivity of information processing, using parallel work or improving the performance of analyzers. A person receives a series of tasks, the solution of which requires the processing of a certain amount of information. The time and the validity of the decision are recorded. The dependence of the average solution time on the amount of information in the problem is determined by correctly solved problems. In accordance with the proposed method, the problems contain calculations of expressions in two algebras, one of which is associative and the other is nonassociative. To facilitate the work of the subjects in the experiment were used figurative graphic images of elements of algebra. Non-associative calculations were implemented in the form of the game “rock-paper-scissors”. It was necessary to determine the winning symbol in the long line of these figures, considering that they appear sequentially from left to right and play with the previous winner symbol. Associative calculations were based on the recognition of drawings from a finite set of simple images. It was necessary to determine which figure from this set in the line is not enough, or to state that all the pictures are present. In each problem there was no more than one picture. Computation in associative algebra allows the parallel counting, and in the absence of associativity only sequential computations are possible. Therefore, the analysis of the time for solving a series of problems reveals a consistent uniform, sequential accelerated and parallel computing strategy. In the experiments it was found that all subjects used a uniform sequential strategy to solve non-associative problems. For the associative task, all subjects used parallel computing, and some have used parallel computing acceleration of the growth of complexity of the task. A small part of the subjects with a high complexity, judging by the evolution of the solution time, supplemented the parallel account with a sequential stage of calculations (possibly to control the solution). We develop a special method for assessing the rate of processing of input information by a person. It allowed us to estimate the level of parallelism of the calculation in the associative task. Parallelism of level from two to three was registered. The characteristic speed of information processing in the sequential case (about one and a half characters per second) is twice less than the typical speed of human image recognition. Apparently the difference in processing time actually spent on the calculation process. For an associative problem in the case of a minimum amount of information, the solution time is near to the non-associativity case or less than twice. This is probably due to the fact that for a small number of characters recognition almost exhausts the calculations for the used non-associative problem.

The article is devoted to the numerical study of shock-wave flows in inhomogeneous media–gas mixtures. In this work, a two-speed two-temperature model is used, in which the dispersed component of the mixture has its own speed and temperature. To describe the change in the concentration of the dispersed component, the equation of conservation of “average density” is solved. This study took into account interphase thermal interaction and interphase pulse exchange. The mathematical model allows the carrier component of the mixture to be described as a viscous, compressible and heat-conducting medium. The system of equations was solved using the explicit Mac-Cormack second-order finite-difference method. To obtain a monotone numerical solution, a nonlinear correction scheme was applied to the grid function. In the problem of shock-wave flow, the Dirichlet boundary conditions were specified for the velocity components, and the Neumann boundary conditions were specified for the other unknown functions. In numerical calculations, in order to reveal the dependence of the dynamics of the entire mixture on the properties of the solid component, various parameters of the dispersed phase were considered — the volume content as well as the linear size of the dispersed inclusions. The goal of the research was to determine how the properties of solid inclusions affect the parameters of the dynamics of the carrier medium — gas. The motion of an inhomogeneous medium in a shock duct divided into two parts was studied, the gas pressure in one of the channel compartments is more important than in the other. The article simulated the movement of a direct shock wave from a high-pressure chamber to a low–pressure chamber filled with a dusty medium and the subsequent reflection of a shock wave from a solid surface. An analysis of numerical calculations showed that a decrease in the linear particle size of the gas suspension and an increase in the physical density of the material from which the particles are composed leads to the formation of a more intense reflected shock wave with a higher temperature and gas density, as well as a lower speed of movement of the reflected disturbance reflected wave.

The paper is devoted to the secondary use of spectrum in telecommunication networks. It is emphasized that one of the solutions to this problem is the use of cognitive radio technologies and dynamic spectrum access for the successful functioning of which a large amount of information is required, including the parameters of base stations and network subscribers. Storage and processing of information should be carried out using a radio environment map, which is a spatio-temporal database of all activity in the network and allows you to determine the frequencies available for use at a given time. The paper presents a two-level model for forming a map of the radio environment of a cellular communication system LTE, in which the local and global levels are highlighted, which is described by the following parameters: a set of frequencies, signal attenuation, signal propagation map, grid step, current time count. The key objects of the model are the base station and the subscriber unit. The main parameters of the base station include: name, identifier, cell coordinates, range number, radiation power, numbers of connected subscriber devices, dedicated resource blocks. For subscriber devices, the following parameters are used: name, identifier, location, current coordinates of the device cell, base station identifier, frequency range, numbers of resource blocks for communication with the station, radiation power, data transmission status, list of numbers of the nearest stations, schedules movement and communication sessions of devices. An algorithm for the implementation of the model is presented, taking into account the scenarios of movement and communication sessions of subscriber devices. A method for calculating a map of the radio environment at a point on a coordinate grid, taking into account losses during the propagation of radio signals from emitting devices, is presented. The software implementation of the model is performed using the MatLab package. The approaches are described that allow to increase the speed of its work. In the simulation, the choice of parameters was carried out taking into account the data of the existing communication systems and the economy of computing resources. The experimental results of the algorithm for the formation of a radio environment map are demonstrated, confirming the correctness of the developed model.