bluuebunny/crossref_metadata_2025_split huggingface dataset:
Features of decomposition of gas hydrate when exposed to microwave radiation
Authors: Davletshina M R , Stolpovsky M V , Chiglintseva A S , Gimaltdinov I K 
Published: September 2020

Abstract
The article summarizes the results of numerical monitoring of the decomposition of gas hydrates in a high frequency electromagnetic field. The results of the numerical experience of the decay process are summarized. In addition, the distribution of temperature and pressure is presented, but in addition, the relationship with the coefficient of permeability. In this article, the features of decomposition of methane hydrate under the influence of microwave radiation are studied. It is shown that the values of temperature and pressure in the reservoir decrease with time and distance from the source of microwave radiation. The dependence of the expansion front coordinate on time for different values of the permeability coefficient is presented.
State-resolved and two-temperature rate coefficients for CO+CO=CO2+C reaction
Authors: Kustova E , Savelev A 
Published: September 2020

Abstract
Several state-resolved and two-temperature models for the rate coefficients of reaction CO+CO=CO2+C are assessed, and a new simple state dependent model is proposed. Various models for the two-temperature non-equilibrium factor are considered: the theoretical alpha-model and the models based on averaging the state-resolved rate coefficients over the Boltzmann distribution. It is shown that for the Starik model, taking into account vibrational excitation of the partner CO molecule as well as the reaction product does not affect the two-temperature reaction rate coefficients. If the vibrational excitation of only one CO molecule is taken into account, the Starik model and that proposed in this work with the parameter U = ∞ yield identical results. However, our model is more general since it is capable to account for the preferential reaction mechanism from high vibrational states. Two-temperature rate coefficients provided by the a-model agree well with the averaged state-to-state ones, but the parameter α cannot be fixed in the entire temperature range and has to be chosen according to the specific ratio T/Tv. Thus, our computationally efficient state-specific model is recommended for state-to-state flow simulations; when being averaged with different non-equilibrium vibrational distributions, it can be used for modeling two-temperature flows.
Effect of coaxially mounted disks on oscillations of a cylinder of large aspect ratio in air flow
Authors: Kaufman D V , Ryabinin A N 
Published: September 2020

Abstract
The damped rotational oscillations of a cylinder whose length-to-diameter ratio is nine are considered. In the head part of the cylinder, a disc is mounted coaxially on the leg. The effect of the disk on damping of oscillations is described by aerodynamic rotational derivatives. Wind tunnel experiment is performed with the flow past a cylinder fixed on an elastic spring suspension. The diameter of the coaxial disk and the distance between the disk and the end of the cylinder vary. Deflected from the equilibrium position, the cylinder performs damping oscillations. The dependence of the amplitude of rotational vibrations on time is determined by the tensometric method. Coefficients of rotational pitch derivatives are found.
Development of power processing unit for a low-power ablative pulsed plasma thruster
Authors: Bogatyi A V , Bogatyi V I , Gordeev S V 
Published: September 2020

Abstract
Research Institute of Applied Mechanics and Electrodynamics of the Moscow Aviation Institute (RIAME MAI) develops ablative pulsed plasma thrusters with low power consumption for small spacecraft. The paper considers the development of power processing unit (PPU) for such thrusters. PPU under discussion should meet the following requirements: design simplicity, small overall dimensions, ensuring the required power and frequency of thruster operation and high energy efficiency.
On stability of planar periodic motions of a satellite in vicinity of resonant rotation
Authors: Churkina T 
Published: September 2020

Abstract
The stability of planar resonant periodic rotations of a rigid body around its centre of mass in a central Newtonian field of forces is considered. The orbit of the centre of mass of the satellite is assumed to be an elliptical one, the body’s inertia ellipsoid is general. Resonant rotations examined mean that the body makes 3 turns around its centre of mass during 2 revolutions of the centre of mass on its orbit (Mercury-type resonance 3:2). For the set of eccentricity value e ε [0,0.25] typical for planets’ ones the regions of stability in the first approximation and regions of unstability are built in three-dimensional space of parameters (eccentricity and two inertial parameters).
The implicit fully coupled numerical method for flows in thermochemical nonequilibrium
Authors: Molchanov A M , Siluyanova M V , Kochetkov Yu M 
Published: September 2020

Abstract
A new effective implicit fully coupled numerical method to compute a high-speed flowfield that is in thermochemical nonequilibrium has been developed. Such a flowfield is described by coupled partial differential equations for the conservation of mass, momentum, total energy, vibrational energies, rotational energy, mass conservation for each species, etc. The total number of equations can be very large, which greatly complicates the solution of general finite volume vector equation when using the standard fully implicit approach. The proposed method allows us to reduce operations with block tridiagonal matrices to inversion of 4x4 matrices and trivial matrix multiplication operations. Moreover, the approximation factorization error is minimized. The numerical procedures were applied to solve chemical and thermal nonequilibrium flow past a sphere body at Mach 27 and chemically nonequilibrium heterogeneous flow in the channel of a combined ramjet with a solid fuel gas generator. The results indicate that new method is 4-5 times more efficient than the standard fully implicit method.
Numerical modelling of the reflected waves from gas cavities and methane bombs in the heterogeneous media of the Northern regions
Authors: Stognii P , Petrov I , Khokhlov N 
Published: September 2020

Abstract
The Arctic region contains lots of underground gas layers closed from the outside. In case of their opening, the gas is of great danger for the surface buildings and drilling equipment. In this work, we observe the main dangerous gas reservoirs – gas cavities and methane bombs. We build the mathematical models of these heterogeneities and presented the main mathematical equations allowing calculating the seismic waves spread through them correctly. The grid-characteristic method of the third order of accuracy is used in all the computations. We demonstrate the results of modelling the seismic waves spread through the heterogeneous medium with the gas cavities and through the homogeneous medium with the methane bomb. The analysis of the differences between the models is carried out. The problems of computing the models with gas cavities and with methane bombs need different approaches for the correct calculations, though the problem formulations are similar.
On the inherent polycrystal stress concentration under external loading on example of single-phase α-Fe samples
Authors: Gulin V V , Nikitin A D 
Published: September 2020

Abstract
It is known that most structural materials are polycrystals. Under any loading, the structural features of the polycrystal may lead to the appearance and accumulation of microplastic deformation due to stress concentrations. This statement is part of a multiscale approach to describing the fracture process. The present development of computer engineering allows modeling of complex non-homogeneous objects, such as polycrystal. In this paper, a numerical model is developed for analyzing of the polycrystal stress state under mechanical loading. It is shown that inherent stress concentration takes place. The localization and statistical estimation of inherent stress concentration is made on the example of α-Fe polycrystal.
Verification of numerical model of temperature calculations in radio-frequency ion thrusters
Authors: Abgaryan V , Balashov V , Kupreeva A , Nigmatzyanov V 
Published: September 2020

Abstract
A numerical model for temperature calculation in radio-frequency ion thrusters (RIT) is proposed. The equations used for heat fluxes determination differ from those used in the known computational models. A new way of distribution of a radiant power flux caused by the excited atoms and ions of the plasma discharge is proposed. In addition, a new radiant flux caused by recombination of ions and electrons on the surfaces bordering the discharge was taken into consideration. The numerical model was verified based on temperature measurements made with the thruster with an ion beam diameter of 8 cm operating at three different power modes. The temperature measurements were made by thermographic camera focused on blackened areas of the accelerating grid surface.
Stability Study of a Relative Equilibrium in the Planar Circular Restricted Four-Body Problem
Authors: Bardin B S , Volkov E V 
Published: September 2020

Abstract
We deal with the restricted planar four-body problem. That is, we consider motion of an infinitesimal small body (particle) under the Newtonian gravitational attraction of three bodies (primaries). It is supposed that primaries move in circular orbits forming Lagrange equilateral triangle; two of them have equal masses. By using the method of normal forms, we perform nonlinear stability study of a central configuration such that the particle is located in perpendicular bisector of the Lagrange equilateral triangle.
Study of methods of supplying a solid phase to a heterogeneous flow at high-pressures of a carrier gas
Authors: Borisov S A , Glukhovskaya Ju I , Dobrovolskiy S V , Platonov I M , Podporin I V 
Published: September 2020

Abstract
The study of the methods of supplying powder material to a supersonic heterogeneous high-pressure flow is carried out in order to determine the optimal type of dispenser that ensures the continuity of the supply of the solid phase to form a coating with anticorrosive properties on metal structures made of the following metal powders: stainless steel, aluminium and zinc or their mixtures using the low-temperature gasodynamic method. Various options for organizing the supply of powder to the main highway were also considered.
Modification of Gaussian elimination: technique, high resolution seismic model for area of natural accumulation of gases
Authors: Smaglichenko T A , Smaglichenko A V , Sokolova N V , Sayankina M K 
Published: September 2020

Abstract
The modification of Gaussian elimination is described here as numerical method to determine the physically adequate solution of the linear equations system that is affected by complexity of the data error (measurements, parameterization et. al.). Other modifications and algorithms are mainly established to efficiently overcome calculating issues. In order to avoid influence of errors in the data the proposed technique selects a set of invertible sub-matrixes. Developing the Tikhonov regularization theory the regularized subsequence is determined for each unknown under consideration. Application of the method to local seismicity data derived high resolution areas and revealed that the hydrothermal field of high concentration CH4 and CO2 is surrounded by rock having high seismic velocity. Based on this result we conclude that nature protects the gas flow due to special structure, which is likely presented by dense basalt. Decrypt of satellite images shows that the zone of lowest elevation does not intersect this structure. Particularities of background seismicity are examined for the gas area being studied. Factors learned from nature experience permit us to formulate conditions to select a place for underground gas storage.
On resonant periodic motions close to conical precession of a dynamically symmetric satellite in a weakly elliptic orbit
Authors: Bardin B S , Antipov A A 
Published: September 2020

Abstract
The motion of a dynamically symmetric rigid body (satellite) about its centre of mass in an elliptical orbit is considered. It is assumed that the eccentricity of the orbit is small and an external resonance caused by gravitational torque takes place. Periodic motions emanating from conical precession of the satellite are studied. Such periodic motions can be constructed in a form of convergent series of fractional powers of the eccentricity. The first terms of these series expansion have been calculated in an explicit form. The bifurcation phenomenon of the above periodic motions is investigated.
Multi-agent modelling of conflicts with uncertainty
Authors: Karandeev A , Osipov V , Baluta V 
Published: September 2020

Abstract
In the framework of the paradigm of the multi-agent modelling system, the features of the adaptive behaviour of agents under conditions of competition with increased uncertainty are often considered. Uncertainty is the result of increased dynamics in environmental conditions. Often these changes are the result of the actions of agents, but there are situations when the conditions change on their own. As a consequence, it would be a reasonable solution to investigate not the entire system at a certain point in time, but the dynamics of the behaviour of objects and participants in the phase space of the conflict state. This allows us to reduce the study of agent adaptation processes in a conflict environment to the analysis of the trajectories of achieving the goal in the state space. Given that the main parameters of the trajectory are the coordinates of the agent in the multidimensional state space at the time of the situation assessment, the degree of adaptation to the situation is characterized by the proximity of the current state to the optimal path leading to the achievement of the goal. The rationality of the ways to achieve the target state is evaluated according to the criteria of admissibility of resource costs and the degree of proximity to achieve the goal.
Longitudinal-transverse (“breathing”) vibration modes of orthotropic plates with and without account of its interaction with the surrounding acoustic media
Authors: Paimushin V N , Gazizullin R K 
Published: September 2020

Abstract
Based on the previously obtained improved equations of motion, the problem of free cylindrical vibration of a hingedly supported plate surrounded by acoustic media is considered. Plate motion equations are obtained taking into account the internal friction of the plate material according to the Kelvin – Voigt model. The motion of acoustic media is described by two-dimensional generalized Helmholtz wave equations, compiled taking into account the internal dissipation of energy by introducing into consideration the complex sound velocity according to Skudrzyk. Based on the obtained solution, a study of resonant nonclassical shearless longitudinal-transverse (“breathing”) forms of free vibrations has been carried out at various values of the physical-mechanical properties of the plate material and the parameter characterizing energy dissipation in the acoustic media surrounding the plate.
Through calculation method of fatigue damage
Authors: Nikitin I S , Burago N G , Nikitin A D , Stratula B A 
Published: September 2020

Abstract
A kinetic model of damage development under cyclic loading is proposed to describe the process of fatigue failure. To determine the coefficients of the kinetic equation of damage, the well-known criterion of multiaxial fatigue failure is used. A numerical method for calculating crack-like zones up to macro fracture is proposed. The results of fatigue experiments for various geometries and asymmetry coefficients were reproduced; the operability of the model and calculation algorithm were verified.
Simulation of seismic responses from the 3D non-linear model of the Bazhenov formation
Authors: Nikitin I S , Golubev V I , Ekimenko A V , Anosova M B 
Published: September 2020

Abstract
The article is devoted to the investigation of seismic responses from probable oil-bearing formations. The three-dimensional geological model of the Bazhenov formation situated at Western Siberia is constructed. It is based on the elastic two-dimensional cross-section with curvilinear boundaries between different layers. For this purpose, logging and seismic data were processed jointly. To describe correctly the internal structure of mudstones the novel continuum model of media with interlayer slippage and delamination was utilized. The grid-characteristic method was used to solve numerically the govern system of the linear elasticity. The non-linearity of the model is incorporated with the appropriate explicit-implicit approximation procedure. For increasing the reliability of obtained synthetic seismograms the presence of the static rock pressure was taken into account. Reasonable computational time was achieved with the help of the parallelization based on the Message Passing Interface (MPI) technology. To analyze the structure of seismic responses wave patterns for the model with different parameters were presented. The influence of fractured layer on registered seismic traces were estimated. The proposed numerical approach may be used for simulation of complex geological objects.
On orbital stability of resonant periodic motions originating from hyperboloidal precession of a dynamically symmetric satellite
Authors: Sukhov E A 
Published: September 2020

Abstract
Periodic motions arising from Hyperboloidal precession of a dynamically symmetric rigid-body satellite on a circular orbit are studied in this work. There exist two types of these motions categorized by frequencies ^ and co2
of the linearized system: short-periodic motions with period close to 2n/co2
and long-periodic ones with period close to 2?!/^ (co2 > co). These motions describe oscillations of the satellite’s principal axis in the neighbourhood Hyperboloidal precession and can be obtained as small-parameter power series of the oscillation amplitude. It has been shown before that in a resonant case there exist more than one family of long-periodic motions. In this work, families of long-periodic motions originating from Hyperboloidal precession in case of fourth order resonance are computed and analysed.
Nonlinear flutter response of cylindrical shell in thermal field and supersonic gas flow
Authors: Baghdasaryan G Y , Mikilyan M A , Vardanyan I A , Panteleev A V , Severina N S 
Published: September 2020

Abstract
The work is devoted to the investigation of flutter oscillations and stability of closed cylindrical shell in supersonic gas flow and placed in an inhomogeneous temperature field. It is assumed that supersonic gas flows on the outside of the shell with an unperturbed velocity U, directed parallel to the cylinder generatrix. Under the action of an inhomogeneous temperature field, the shell bulges out; this deformed state is accepted as unperturbed, and the stability of this state is studied. The main nonlinear equations and relations describing the behavior of the examined system are derived. The formulated boundary value problem is solved using Galerkin method. The joint influence of the flow and the temperature field on the relation between the amplitude and frequency of nonlinear oscillations of a cylindrical shell is studied. The critical velocity values are calculated from the corresponding linear system and are given in tables. The numerical results show that: a) the surrounding flow significantly affects the nature of the investigated relation; b) it is impossible to excite steady-state flutter oscillations (the silence zone) up to a certain value of the oscillations frequency; c) the dependence of the amplitude on the oscillations frequency can be either multi-valued or single-valued.
Benchmark analysis of novel multi-agent optimization algorithm using linear regulators for agents motion control
Authors: Karane M , Panteleev A 
Published: September 2020

Abstract
The aim of this paper is to develop algorithm and software for a novel multi-agent constrained global optimization method. In multi-agent algorithms, the solution search area is populated with agents. Some transformations occur over them, which lead to a global extremum. It was proposed to take as a basis the use of linear regulators to control the movement of agents group. At each stage of the algorithm, a search is made by closed loop agents control with various types of criteria. Using criteria of various types, a more detailed study of the solution search area and finding a global extremum is provided. This is the main feature and novelty of the algorithm under consideration. The method efficiency is studied on a standard set of test functions of two variables with a complex structure of level lines using the software developed. Efficiency analysis is carried out for Schweffel function and multifunction from the benchmark set. During the study, statistical characteristics were calculated, according to which the most suitable parameters were selected. The results obtained indicate that the algorithm successfully copes with such problems and can be used, for example, for problems in the theory of optimal control of dynamic systems.
Application of bio-inspired methods for optimal open loop discrete time deterministic control problems
Authors: Panteleev A V , Stanovskaya Y V 
Published: September 2020

Abstract
The article proposed the novel Sparrow colony optimization (SCO) algorithm to solve the optimal open loop control problem for nonlinear discrete deterministic dynamic systems described by difference equations. Numerical algorithm and software in Python programming language are implemented. Model examples demonstrating the effectiveness of the developed software are solved. Comparison of the considered algorithm results with a Dragonfly optimization algorithm at the solution of model problems is made. The recommended parameters values of the proposed algorithm are suggested.
The mini-batch adaptive method of random search (MAMRS) for parameters optimization in the tracking control problem
Authors: Panteleev A V , Lobanov A V 
Published: September 2020

Abstract
The tracking control problem for nonlinear dynamic system linear in control and signal tracked is considered. It is proposed to formalize the tracking problem as a problem of controlling a bunch of trajectories emanating from a given set of possible initial states. The quality of a single trajectory control is described by the value of the integral criterion, which depends on the square of the tracking error and the intensity of the control used. The control is sought from the condition of the minimum value of the average criterion defined on the set of the bunch trajectories. When choosing a control structure, the well-known result was used that provides internal stability and the desired quality of the output control. The unknown parameters of the control law within the selected structure are found using the new mini-batch adaptive method of random search (MAMRS). This new optimization algorithm combines the ideas of the adaptive random search and stochastic gradient descent methods. The examples of solving the tracking problem as a result of parametric optimization of controlling a bunch of trajectories are presented.