bluuebunny/crossref_metadata_2025 huggingface dataset:
A two-stage opinion formation model based on the extended XY-magnet interaction and socio-dynamic update mechanism
Authors: Prenga D.
Published: December 2019

We introduce herein a two stage model of opinion formation in a community of individuals which share strong interests within a permanent pair, and attend also a persuasion social process with others to finalize their attitudes. In the first step, individuals behave as member of their couples and seek to optimize respective satisfaction. Then, they modify their attitudes inherited from the first stage throughout a persuasion process and social influence. The first stage consists in an extension of a classical XY magnet model, and the calculation in this step are performed using statistical mechanics tools. At the end of this phase, each opinion agent has adapted its support Ox for the issue F and the agreement within their pair O = |
O
1 + O
2
|. The evaluated quantities Ox
(i) depend on the magnetic-like system parameters J, T, F and on the extra parameter α(i) which embodies the dissimilarity of the system utility from the reference Hamiltonian. The set {Ox
(i), O(i)} represents the opinion state of the community straightaway after the first stage, and is presented hereto with respective histogram. We observed that histograms of Ox
(i) approximate to q-Gaussian distributions for moderate F/T ratio, and approaches to power law distributions for low F/T ratio. The histograms of the inner agreement O(i) do not fit well to a given distribution, and therefore, the social comportment which we identify hereto with this set, is not a stationary quantity under this approach. Next, the opinion quantities Ox
(i) will pursue an update course as result of the persuasion process and social influence. We performed the calculation based on Deffuant and Heglesman models by using Ox
(α
i
)
F,J,T
as initial opinion values. We observed that the final opinion fragmentation resulted lower than when using standard assumptions of those models and also, the time to consensus was shorter. Next, for the special case where there are only two output final opinion values, the lower one needs more iteration time steps to converge. In our approach, usually the lowest level opinion converge slower than higher ones. Finally, we have implemented a modified preferential attachment model to realize a network of the linked nodes based on the opinions Ox
inherited from the early stage. We acknowledged the power law distribution of the grades of nodes, but in our case there are no disturbances in the queue of the histogram, which are common in the standard simulation for such networking process. As conclusion, having regard to every aspect and specifics, we believe that the proposed model would help on the understanding of the complexity of social conduct.
The Solution Cosmological Constant Problem. Quantum Field Theory in Fractal Space-Time with Negative Hausdorff-Colombeau Dimensions and Dark Matter Nature
Authors: Foukzon Jaykov , Men’kova Elena R , Potapov Alexander A
Published: December 2019

The cosmological constant problem arises because the magnitude of vacuum energy density predicted by quantum field theory is about 120 orders of magnitude larger than the value implied by cosmological observations of accelerating cosmic expansion. We pointed out that the fractal nature of the quantum space-time with negative Hausdorff- Colombeau dimensions can resolve this tension. The canonical Quantum Field Theory is widely believed to break down at some fundamental high-energy cutoff Λ* and therefore the quantum fluctuations in the vacuum can be treated classically seriously only up to this high-energy cutoff. In this paper we argue that Quantum Field Theory in fractal space-time with negative Hausdorff-Colombeau dimensions gives high-energy cutoff on natural way. We argue that there exists hidden physical mechanism which cancel divergences in canonical QED
4, QCD
4, Higher-Derivative - Quantum-Gravity, etc. In fact we argue that corresponding supermassive Pauli-Villars ghost fields really exists. It means that there exists the ghost-driven acceleration of the univers hidden in cosmological constant. In order to obtain desired physical result we apply the canonical Pauli-Villars regularization up to Λ*. This would fit in the observed value of the dark energy needed to explain the accelerated expansion of the universe if we choose highly symmetric masses distribution between standard matter and ghost matter below that scale Λ*,i.e., fs.m
(µ) ≈ −fg.m
(µ), µ = mc, µ ⩽ µ
eff, µ
eff < Λ*/c. The small value of the cosmological constant explaned by tiny violation of the symmetry between standard matter and ghost matter. Dark matter nature also explaned using a common origin of the dark energy and dark matter phenomena.
Robust stability of a class of differential systems with state after-effect dynamics
Authors: De la Sen M.
Published: December 2019

This paper is concerned with the investigation of the global stability and global asymptotic stability of the error with respect to its nominal version of a non-linear time-varying perturbed functional differential system which is influenced by point, finite-distributed and Volterra-type distributed delayed dynamics. The boundedness of the error and its asymptotic convergence to the zero equilibrium are investigated and some formal “ ad- hoc” results are proved.
Modeling of the process of treatment of polluted washing water in circulating water systems
Authors: Melekhin AA
Published: December 2019

Optimization of the process of treatment of circulating water is an important scientific and technical task. Consideration of this issue is proposed on the example of cleaning washing water. The creation of water use systems at industrial enterprises in the recycling cycle is associated with the need for a new approach to the formulation of research, design and operation of water recycling systems. The modeling of the process of cleaning polluted washing water in circulating water use systems and solutions to the problems of optimizing the process parameters. We have elaborated a mathematical model of management of circulating water system. Thus, application of the offered technique allows to solve a problem of optimization of process of purification of the polluted waters for circulating systems of water consumption. On the basis of this technique the technological scheme of cleaning of the polluted washing waters is developed is based on application of a combination of ways of destruction of structure of pollution and ways of separation of the destabilized pollution. The technological scheme of cleaning contaminated washing water is based on a modular method of constructing a cleaning device, which is based not on individual ingredients or their dispersion, but on the type of contaminants present: pop-up, sedimentary, suspended-emulsified contaminants.
A multi-temperature kinetic Ising model and its applications to partisanship dynamics in the US Senate
Authors: Mazilu I. , Lorson A. P. , Gibbs S. , Hanstedt W. , Mazilu D. A.
Published: December 2019

As the political landscape becomes increasingly complex, the classic paradigms used in political science have failed to remain relevant and other methods of study are needed. We introduce a population dynamics model and a multi-temperature kinetic Ising model to analyze the partisanship dynamics of the US Senate. We use Monte Carlo simulations, mean field theory and numerical analysis of the master equation of a system of 100 senators (agents) separated into various categories based on their political leanings and interactions with each other. Results show an interesting development of partisanship between the agents after a short time. The model can be extended to other cooperative stochastic systems in physics and social sciences.
Pressure - velocity projection method with mixed type approximation for Oseen discrete operator
Authors: Evstigneev Nikolay M. , Ryabkov Oleg I.
Published: December 2019

We are considering the problem of divergence - free projection in rectangular domains for the Oseen (stationary Navier-Stokes) operator. It uses nodal Finite Element method to reconstruct pressure and Finite Difference method for scalar functions and vector functions for other parts of the equations. This allows us to use simple finite difference schemes for linear part and WENO-type schemes for the the nonlinear part in the space of discrete velocities. The boundary conditions are formulated in Finite Volume conservative approach for velocity and in Finite Element approach for pressure. We illustrate that the convergence rate depends on the smoothness of the projected function and that the projection method allows one to obtain divergence-free solutions with desired tolerance. We numerically analize the projection operator that acts in the space of divergence operator image. It is shown that all eigenvalues of the operator are less than unity for Oseledets-type wall boundary conditions for velocity and zero Neumann conditions for the Poisson equation. We show that for smooth functions we obtain forth order convergence in divergence. Finally we demonstrate the method by solving the stationary lid driven cavity problem for the 2D Oseen operator.
Numerical model of evaporation of tungsten in vacuum under high-power transient heating
Authors: Lazareva G G , Arakcheev A S , Maksimova A G , Popov V A
Published: December 2019

On the BETA facility, an electron beam is used for simulation of pulsed thermal loads on ITER-relevant tungsten. Numerical experiments are used for verification of the models. This paper presents extension of the model of electron beam heating, supplemented with dynamics of gas evaporation from a heated surface in vacuum.
Logistic map as a Fourier’s series expansion: numerical analysis
Authors: Lawnik Marcin
Published: December 2019

Logistic map is one of the simplest, and at the same time the most commonly used dynamic system, which is characterized by chaos. The article presents approximations of the logistic map through its extension into the Fourier’s series. Obtained in such way dynamical systems were analyzed, among others for the Lyapunov exponent and bifurcation diagrams. Furthermore the issue of the density of the iterated variable and some applications in chaos based cryptography were commented.
Structure and properties of atomic nuclei in the theory of compressible oscillating ether
Authors: Magnitskii Nikolai
Published: December 2019

In the work, based on the equations of the compressible oscillating ether, derived from the laws of classical mechanics, ether mathematical models of the nuclei of atoms of chemical elements are constructed. It is shown that the nucleus of any atom is a superposition of perturbation waves of ether density in several protons and several neutrons, having a common center and propagating around a common axis in one direction or in opposite directions, that is, having unidirectional or oppositely directed spins. Formulas for the values of internal energies, masses, magnetic moments, and binding energies of atomic nuclei are derived, with an accuracy of fractions of a percent coinciding with their experimental values. Formulas for calculating the radii of atomic nuclei are obtained. Answers are given to many topical questions about the structure of atomic nuclei that modern atomic physics is not capable of answering, for example: why there are no nuclei consisting only of protons or only of neutrons; what is the nature of the nuclear forces holding together protons and neutrons in the nucleus; why the sizes of atomic nuclei practically do not depend on the atomic number of the chemical element; why the Coulomb barrier of the nucleus selectively works; why the fragments of the decomposition of heavy elements into two nuclides are asymmetric; what is the reason for the different percentage in nature of different isotopes of the same chemical element?
Design of narrowband multiplierless comb compensator with low passband deviation
Authors: Dolecek Gordana Jovanovic
Published: December 2019

The simplest decimation filter is a comb filter which has all coefficients equal to unity, and consequently does not require multipliers for its implementation. However, comb filter does not have the flat passband characteristic, which is increases with the increase of the number of cascaded comb filters. The passband droop must be compensated by a filter called comb compensator. In this paper we present novel narrowband multiplierless compensator which results in a low absolute value of the passband deviation of the compensated comb, which is less than 0.01dB. The compensator has a magnitude response synthesized as sine wave functions. The parameters of design are the amplitudes of sine wave functions, which depend on the order of the comb filter and practically do not depend on the decimation factors. The designs for two values of the passband edge frequencies are elaborated and illustrated with examples.
Magnetorheological gel-based magnetoresistor: Effects of a static and a periodic time-varying magnetic field on the electrical resistance
Authors: Bica I , Cîrţînă L , Cîrţînă D , Chirigiu L , Chirigiu L M E
Published: December 2019

A magnetoresistor having as resistive element a magnetorheological gel (MG) based on silicone rubber and Fe microparticles is fabricated. An experimental setup is built and described for measuring the electrical resistanceRof the magnetoresistor in a static and in a periodic time-varying magnetic field (PTVMF). The results show that the resistance is significantly influenced by increasing the magnetic flux density, and the PTVMF induces transient processes inside the magnetoresistor. We explain these processes.
Application of the artificial neural network in the forecasting of the airborne contaminant
Authors: Wawrzynczak A , Berendt-Marchel M.
Published: December 2019

Release of hazardous materials in chemical industries is a significant threat to surrounding areas. This thread can be answered by the reconstruction system capable of localizing the source of airborne contamination solely based on substance concentrations recorded by the sensors network. However, such systems require multiple runs of the selected atmospheric contaminant transport model. The complexity of the contaminated terrain involves the application of the complicated and computationally expensive dispersion models, while the fast one is too simplified. We examine the possibility of training an artificial neural network (ANN) so that it could effectively simulate the atmospheric toxin transport. The use of a fast neural network in place of costly computational dispersion models in systems localizing the source of contamination might significantly improve their efficiency (speed). In this paper, we train the ANN with the use of the training dataset covering the contamination source term parameters and point output concentrations generated by the Gaussian dispersion model. We test various ANN structures, i.e., numbers of ANN layers, neurons, and activation functions to achieve the ANN capable of estimating the contaminant concentration. Applying the specified ANN topology we train ANN with use of the real field Prairie Grass experiment data. The performed tests confirm that trained ANN has the potential to replace the dispersion model in the contaminant source localization systems.
Numerical solution of flow in bypass for generalized Newtonian fluids
Authors: Keslerová Radka , Řezníček Hynek , Padělek Tomáš
Published: December 2019

This work presents the numerical solution of generalized Newtonian fluids in the bypass geometry. The considered geometry consists of the narrowed host tube and the bypass graft with 30, 45, 60 degrees angle of the connection. Two values of the Reynolds number, 100, 200, are tested. The numerical results of non-Newtonian fluids are compared to the results of Newtonian fluids. The governing system of equations is based on the system of balance laws for mass and momentum. Generalized Newtonian fluids flow in the bypass tube is numerically simulated by using SIMPLE algorithm included in OpenFOAM.
Soliton surfaces for complex modified Korteweg–de Vries equation
Authors: Bauyrzhan Gulnur , Yesmakhanova Kuralay , Yerzhanov Koblandy , Ybyraiymova Sveta
Published: December 2019

In mathematics and physics, one of the main tasks is to relate differential geometry and non-linear differential equations, which means that the study of particular cases of subvarieties, curves, and surfaces are of great importance. Soliton surfaces associated with the integrable system play an essential role in many problems with the physical application. In this paper, we study the complex modi ed Korteweg de Vries (cmKdV) equation. It is well known that the cmKdV equation is a very important integrable equation. We present the relationship between an integrable system and soliton surfaces and namely Lax representation of the cmKdV equation was used to obtain the rst and second fundamental forms, surface area and curvature.
Optimal control synthesis for affine nonlinear dynamic systems
Authors: Bagdasaryan Armen
Published: December 2019

The problem of optimal control synthesis of complex nonlinear and multidimensional systems oriented on the building of integrated control systems with the adaptation and self-organization properties is of much current interest. The development of optimization methods employed in control problems demonstrated their effectiveness and has led to the construction of algorithms of approximate solution of optimization problems that significantly extends the class of control problems that can be set. In this work we consider a synthesis of optimal control for affine nonlinear system, in which a special emphasis is placed on the degenerate problems of optimal control. Our approach is based on the extension of the method of minimization of generalized work function by properly transforming the initial nondegenerate problem of optimal control into degenerate problem of optimal control synthesis. The search for the solution is based on the suboptimal strategy that includes the construction of minimizing sequences that converge interval-wise to the optimal solution of the initial problem. We obtain some optimality conditions as well as the necessary and sufficient conditions of existence of optimal solution.
HodgeRank as a quantitative tool in social representations theory
Authors: Pereira Ana L , Lunardi José T , Calçada Marcos , Viviane A Bagio
Published: December 2019

HodgeRank is a technique proposed by Jiang et al that provides a way for ranking data elements based on the relative importance that individuals associate to them. This technique has the advantage of working fine with incomplete and imbalanced data, besides providing a measure for the inconsistencies of the outcome. In this work we propose to use HodgeRank as a complementary quantitative tool for analysing the content and the structure of a Social Representation, in which data are spontaneous evocation of words or phrases by a group of individuals; such words or phrases are induced by a term which constitutes the object of the representation under study.
Econometric assessment of the world energy market impact on the incomes of the consolidated budget of Russia
Authors: Absalyamova S , Zulfakarova L , Ivanova N , Mukhametgalieva C
Published: December 2019

The article is devoted to the study of modern trends in energy resources megamarket. The results of the study reveal a system of factors affecting the production and consumption of energy resources in the global economy. The authors make a forecast of the development of traditional and alternative energy in the coming decades. The paper assess the degree of influence of the changing conjuncture of the world energy market on the Russian economy. The study shows the presence of high closeness of communication on the Chaddock scale and the direct linear dependence of Russia’s GDP at current prices on the volume of oil and gas revenues of the consolidated budget of the Russian Federation, confirmed by calculating the Pearson correlation coefficient. The article proposes a set of measures that reduce the dependence of the Russian budget on the world energy market.
Particle-based modeling of the mechanical behavior of porous fluid-saturated viscoelastic solids
Authors: Shilko E V , Dimaki A V , Popov V L
Published: December 2019

In the paper, we developed a macroscopic discrete element model of permeable fluid-saturated materials with solid skeleton characterized by viscoelastic rheological properties. The Biot’s linear model of poroelasticity was used as a mathematical basis for describing the mechanical interrelation between the solid skeleton and interstitial fluid. Using this model, we numerically studied the dependences of the effective Young’s modulus and strength of fluid-saturated viscoelastic materials on the loading rate, sample size and the mechanical parameters, which determine the relaxation time of the solid-phase skeleton and the time scale of redistribution of fluid in the pore space. We revealed two dimensionless control parameters that determine the dynamic values of the effective mechanical characteristics of the samples under compression loading. We obtained the general relations that describe the above-mentioned dependences in terms of the two proposed control parameters. These relations have a logistic nature and are described by sigmoid functions. The importance of the proposed empirical expressions is determined by the possibility of their application for predicting the mechanical response of fluid-saturated materials of different nature (bone tissue, rocks, porous materials with polymeric skeleton, including elastomers, etc.) under dynamic loading.
Numerical modeling of Liesegang structures formation process under an electric field influence
Authors: Kireev V , Shalabayeva B , Jaichibekov N , Nizamova A , Kozhabay Z
Published: December 2019

In the present paper the formation of Liesegang structures, i.e. the process of periodic deposition with the mutual diffusion of two reacting chemicals in the presence of an external constant electric field, is studied using numerical modeling. The mathematical model of the process consists of three differential equations of diffusion-reaction for the concentrations of the initial components and the resulting precipitate. The kinetics of sedimentation is described in accordance with the Ostwald’s supersaturation theory. The equations of the mathematical model in one-dimensional and two-dimensional statements were solved numerically using the control volume method using computer code written by the authors in the C ++ language. As a result of numerical simulation in the absence of an electric field, periodic structures were obtained formed of the precipitate, which qualitatively corresponds to the patterns observed in the experiments. It is shown that numerically obtained Liesegang rings satisfy the well-known laws: the ratio of the distances to neighbouring rings remains constant and there is a power dependence between the distances to the rings and the time of their formation. The influence of the ratio of the concentration of the starting substances and the electric field strength on the nature of the structures formed is investigated. It also has been shown that an increase in the electric field strength leads to an increase in the number of structures formed.
Micromagnetic simulation of thickness-dependent magnetization reversal processes in elongated iron nanodots
Authors: Sudsom D , Döpke C , Blachowicz T , Ehrmann A
Published: December 2019

Micromagnetic simulations were used to investigate magnetization reversal processes in elongated ferromagnetic nanodots, prepared by combining two half-circles with a rectangle. The micromagnetic simulation program OOMMF is based on dynamically solving the Landau-Lifshitz-Gilbert equation of motion. Material parameters were chosen as typical for Fe (iron). Lateral dimensions were in most simulations chosen as 730 nm x 133 nm, while the dot height was varied between 3 nm and 54 nm. For different in-plane angles of the external magnetic field, varying magnetization reversal processes were found with changing dot thickness, offering a possibility to tailor magnetic states by modifying the thickness of the nanodot.
Development of cognitive competences in physics in students of Biology
Authors: Escobar J H , García-Gómez L , González J D
Published: December 2019

A computational method that contributes to the development of cognitive competences, in students of biology of Magdalena University, is based on the use of a novel environment of virtual experiences of physical systems. This article investigates the level of learning achieved through the implementation of virtual laboratories that can be used by the user to work in web environments and mobile devices. Conceptual tests were administered to evaluate students’ competences before, during and after instruction. We present some perceptions and comments of the students regarding the virtual laboratories of Newtonian mechanics and we conclude on their effectiveness in the development of cognitive competences.
Study of the fundamental interactions in the bounded states of the systems: Earth-Moon, Proton-Electron (hydrogen atom), positronium (process e- e+→e- e+), and quarkonium, ( QQ)
Authors: Beltrán J R , Escobar J H , González J D
Published: December 2019

All The bound states of two particles such as the earth-moon system, bound by the gravitational interaction, proton-electron pe
− hydrogen atom, positron-electron (e
+
e
−) positronium linked by the electromagnetic interaction and quark-antiquark (

(

q

q
¯

)

) quarkonium linked by strong interaction, provide physicists with a natural laboratory to study these interactions. In this paper we review the classical theories formulated by Newton and relativist due to Einstein of gravitational interactions to study the earth-moon system. As regards the bound states (pe
−), (e
+
e
−) and (

(

q

q
¯

)

) we used Schrödinger equation to calculate the energy spectrum of these systems, as well as the Feynman diagrams at tree order to determine in some detail the Hamiltonian of these systems, known as Breit-Fermi potential. The similarities and differences between the hydrogen atom and the positronium are analyzed. The quarkonio is studied in the framework of the non-relativistic quark model (MQNR), heavy quark, where the relativistic effects are negligible, confronting the theoretical and experimental results to observe its validity.
Scientometric Study of Superconductivity Research in South America from 1980 to 2019
Authors: González J D , La Hoz J De , Beltrán J R
Published: December 2019

This paper presents the scientometric analysis of superconductivity research output in South America from 1980 to 2019 and compares it with Global output as reported in Web of Science. The study shows that superconductivity research in South America had a steep growth between 1980 and 2000, particularly an abrupt hike in 2005 that is noticeable followed by a more or less steady pattern thereafter up to 2019. South America superconductivity papers are analysed bibliometrically to indicate the authorship, collaboration pattern, to identify the major institutions and most relevant journals; apart from identifying the research field or application area of research in superconductivity.
Poincare decomposition theorems and the Lomov regularization method
Authors: Kachalov Vasily
Published: December 2019

An important stage in the development of the differential equations analytic theory was the Poincare decomposition theorems. They assert the existence and uniqueness of solutions of initial problems for normal systems of differential equations, which are analytically dependent on a small parameter, provided that the right-hand sides are functions analytic in this parameter. If the Cauchy problem is singularly perturbed, then, in the general case, the solution will not be analytic in a small parameter. Nevertheless, within the concept of the regularization method of S. A. Lomov, the conditions for the existence of so-called pseudo-analytic solutions were found.
Numerical and statistical modeling based investigation of the detection efficiency of high-spectral-resolution lidars at different laser radiation wavelengths
Authors: Evgenieva Tsvetina , Anguelov Vladimir , Gurdev Ljuan
Published: December 2019

In the present work, a numerical and statistical modeling approach is developed for estimating the operation efficiency of high-spectral-resolution lidars (HSRLs), when determining the atmospheric aerosol extinction profiles along the lidar line of sight (LOS) at different sensing (laser) radiation wavelengths from the UV, VIS and NIR spectral ranges. The efficiency estimation is based on numerical modeling of the lidar signal profile along the LOS and the corresponding profile of the signal-to-noise ratio (SNR) of its measurement. The optimally efficient wavelength (at certain distances along the LOS) is that ensuring maximum signal strength and SNR and, consequently, brighter and clearer lidar images of specific aerosol objects and background. The results about the optimum wavelengths obtained under different atmospheric-turbidity conditions (clear or hazy atmosphere), in the presence of cirrus clouds, are proved by statistical modeling and processing of realistic (noisy) lidar profiles and recovering the atmospheric extinction profiles along the LOS. It is shown that up to certain characteristic altitudes (that are lower at higher turbidity) the UV wavelengths are advantageous in the above sense. Above the mentioned altitudes, successively, first the VIS and then the NIR wavelengths become more efficient compared to the UV wavelengths.
Trajectory portraits for the two perturbed centrally symmetric systems of point vortices
Authors: Boyarintsev V. D. , Boyarintseva T.E. , Gvozdev N.P. , Kobzeva V.M.
Published: December 2019

We describe the types of motion for two centrally symmetric systems of point vortices (in one vortices are located in the corners of a regular hexagon, in the other – in the corners of a regular octagon), caused by spatially periodic perturbation: in which the vortices are in the corners of two regular triangles or two squares with a common center.
Development of combined search methods for efficiency indicator extreme in variation statement of forecasting tasks for determine characteristics of composite materials
Authors: Gusev E L , Bakulin V N , Chernykh V D
Published: December 2019

Modified search methods for global extreme of multiparameter functions are studied, considering the structural features of efficiency criteria used in problems of forecasting residual life and durability of structures made of composite polymeric materials. Comparative and qualitative studies have been carried out and methods have been developed to select the most promising areas of search for the absolute minimum of the studied performance indicators in refined variation formulation of inverse problems of forecasting residual life of composites.
About orientational instability in nematic liquid crystal films
Authors: Kalugin A G , Pavlov D V
Published: December 2019

In the presented work the role of the surfacelike (splay-bend) elastic constant in the Frank’s energy of nematic liquid crystals for orientational instability in the thin nematic films is considered. It is shown that nontrivial periodical perturbations exist in the nematic film with undisturbed planar director orientation in case of sufficiently large value of splay-bend constant. For these solutions the relations between splay-bend constant, another Frank’s constants and layer thickness are received and studied. These correlations allow us to make new explanation for certain experimental effects and to present method for surfacelike constant value measurement.
Aeroelastic stability of a shell supported by a cylinder with a hole of linearly varying radius
Authors: Konopelchev M A , Bakulin V N , Ya Nedbai A
Published: December 2019

The aeroelastic stability of a shell supported by an elastic cylinder of varying thickness with the outer surface exposed to supersonic gas flow is studied. The supporting cylinder is considered as an elastic foundation, whose bedding value is determined from the equations of the three-dimensional theory of elasticity. The solution is obtained by the BubnovGalerkin method in the form of a trigonometric series in the axial coordinate. The characteristic equation is approximated by the Lagrange polynomial, whose stability is investigated with the use of the Routh-Hurwitz criterion. The dependences of the critical flow velocity on the length of the cylinder section with the tapered hole are shown for various values of the axial force, the damping decrement, and the shell thickness.
Model Estimates of Circulating Flow around Objects in the Marine Medium and Atmosphere
Authors: Korchagin N.N , Vladimirov I.Yu
Published: December 2019

Model studies of force action on streamlined fragments of technical structures by a stratified sea current have been carried out. Analytical expressions are obtained for the hydrodynamic load on a point dipole during its circulation flow around a two-layer fluid flow of finite depth. The dependences of the wave resistance and the lifting force on the velocity of the current and circulation are investigated. It is shown that taking into account the velocity circulation can significantly affect the force effect on the dipole. The effect of a sharp (reversible) change in the direction of lift in a relatively narrow range of the flow velocity of a pipeline fragment simulated by a dipole has been found. The effect can also appear when moving self-propelled underwater objects and aircraft in the atmosphere.
Non-uniqueness of transonic flow in an intake-type channel
Authors: Kuzmin A.
Published: December 2019

The two-dimensional turbulent airflow in a 9-degrees-bent channel is studied numerically. Inner surfaces of the top and bottom walls are parallel to each other upstream and downstream of the bend. The free stream is supersonic, whereas the flow is subsonic at the channel exit. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with a finite-volume solver using the Spalart-Allmaras and Shear Stress Transport k −! turbulence models. The solutions reveal a flow hysteresis and non-uniqueness in considerable bands of the free-stream Mach number, angle of attack, and exit pressure. At the endpoints of the bands, there are abrupt changes of the shock wave system. The non-uniqueness admits different losses of the total pressure, which may cause different trusts of an air breathing engine.
The problem of suspension injection into a porous medium within a two-velocity model of deep bed filtration
Authors: Leontiev N E
Published: December 2019

We consider flows of a suspension through a porous medium with account of the deposition of the suspended particles onto the internal surface of a porous matrix (deep bed filtration). The velocities of the suspended particles and the carrier fluid are plausibly supposed to differ by a known factor that depends on the suspension concentration. We present analytical and numerical solutions to the problem of suspension injection into a porous sample. The main qualitative result of the investigation is that — under certain circumstances — the smooth solutions (i.e., the ones that do not, in contrast to usual assumptions, involve concentration jumps) to the problem may exist. This feature may be of use for experimental data interpretation.
The effect of an additional air inlet in the hot outlet area on the overall effectiveness of a vortex tube
Authors: Privalov L Y , Mikhaylenko C I
Published: December 2019

In this paper the modification of a vortex tube is shown. The feature of this vortex tube is that it has an additional air inlet in the hot outlet area along the tube axis designed to redistribute air consumption between cold and hot outlets. Computational experiments are done in openFOAM toolbox using sonicFoam solver. In order to increase computational speed the mesh is being decomposed into equal parts, which allows for the parallel run using MPI on a single computer. The results of the experiment show temperature values and air consumption on the corresponding outlets in relation to the change of the vortex tube length. A conclusion about the effective vortex tube length is made.
On a theorem of impulse and energy to determine parameters of the electric jet engine KA
Authors: Sidnyaev Nikolay
Published: December 2019

The report presents the modern physical principles of acceleration of charged particles and plasma in electric and magnetic fields, which are the basis for the classification of electric rocket engines. It is shown that for reactive means of correction of orbit parameters the lifetime depends to a greater extent on the reserves of the working fluid and the corresponding thrust and energy for the propulsion system. It is postulated that the special value of the determination of pulses and energy for electric propulsion (ERD) is that their application makes it possible to obtain an idea of these phenomena on the boundary surface of a certain area, without knowledge of the individual phenomena occurring within the ERD. That is, often in cases where the differential equations of plasma flow can not be composed or at least can not be integrated, the theory of pulses or energy makes it possible to know the nature of the movement in its General features. It is convincingly proved that the theorems of impulses and energy are a convenient means for checking the correctness of the results, including experimental ones.
Estimation of maximum water levels during spring flood on Lena river parts using artificial neural networks
Authors: Struchkova G. P. , Kapitonova T. A. , Timofeeva V. V. , Nogovitsyn D.D.
Published: December 2019

The Republic of Sakha (Yakutia) possessing a vast territory located in various climatic zones and a developed network of water bodies is exposed to a wide range of natural emergency situations. Among them, spring-summer floods are the most frequent and bringing enormous damage, causing inundations of vast areas and national economy objects, which determines relevance of development and improvement of flood forecast methods for implementation of timely measures to prevent and reduce an inundation risk.

Artificial neural networks have proven their effectiveness in solving various forecast problems, especially when using statistical data. In particular, usage of a neural network approach based on the forecast of a time series from previous values gives good results. The artificial neural networks, unlike statistical methods of analysis, are based on parallel data processing, have an ability of self-learning and recognition of nonlinear relationships between input and output data sets. A choice of parts of the Lena river to predict maximum water levels during the floods was determined based on locations of potentially hazardous objects, the inundation of which can cause the considerable material damage. On the basis of the hydrological data obtained during 70 years, the neural network models are obtained, which make it possible to predict flood hazards from the spring floods, two variants of the transformed initial data are considered and different network structures are compared. Relative errors of the forecasts obtained during the work vary considerably (7–20%), which indicates necessity for the processing of the initial data and careful selection of the structure.
Estimation of Near-Bottom Suspension-Carrying Flow around a Pipeline
Authors: Vladimirov I.Yu , Korchagin N.N
Published: December 2019

In a model format, the force effect of a stratified ideal fluid flow on streamlined elements of engineering structures is investigated. Integral representations of wave drag and lift force are obtained. Numerical calculations are performed for the real marine medium. The conditions under which significant changes in hydrodynamic reactions to streamlined elements of technical structures occur are revealed.
On hyperbolized nonlinear Schredinger type equations
Authors: Yunakovsky A.D. , Bogomolov Ya.L. , Sapogova N.V.
Published: December 2019

A nonlinear Schredinger type equation in the case of an unbounded in space operator having, a non-divergent form, is considered. A new approach based on the hyperbolization procedure is suggested. The possibilities of the method proposed are tested.
Numerical modelling of wall-bounded turbulent flows based on the CABARET scheme
Authors: Asfandiyarov Danil
Published: December 2019

In this study, the classical problem of turbulent plane channel flow at Rem
= 13750 and Rem
= 21900 is investigated using a numerical algorithm based on the CABARET scheme. Simulations are performed on the fine grids, resolving all the spatial scales of the turbulence according to a direct numerical simulation approach, as well as on coarse grids standard for large eddy simulation of wall-bounded turbulent flows. In the latter case, in order to obtain a more accurate representation of the momentum transfer towards the wall, artificial boundary conditions are introduced. It allows modelling with high accuracy the mean flow characteristics. Numerical results obtained by the CABARET scheme are compared with numerical results obtained by pseudospectral method.
Models of dynamics of contamination propagation in surface waters using simulation of hydrodynamical processes of different level of complexity
Authors: Cherepanov Anatoly , Sorokovikova Olga
Published: December 2019

This paper uses the ideology of solving hyperbolic equations using the Euler balance-characteristic approach, which allows economically and correctly resolving the dynamics of pollution propagation processes with large concentration gradients characteristic of an accident. The purpose of the study is to develop a three-dimensional model of advectiondiffusion in a non-uniform velocity field and non-isotropic field of turbulent diffusion, taking into account some physical processes: gravity sedimentation, sediment accumulation and their dynamics. As well as the implementation of the interaction model with the hydrodynamic module, based on solving the equations of the theory of shallow water in the approximation of Saint-Venant.
Probabilistic models of pollution of the surface waters of large marine areas
Authors: Sorokovikova Olga , Dzama Dmitry , Asfandiyarov Danil
Published: December 2019

Version of Monte-Carlo model for calculation of propagation of contamination in large marine areas with taking into account a coastline is presented. Based on long standing database of sea currents, bathimetry, and mixed layer depth, the probabilistic model of zoning marine areas by concentration of pollutant is offered. In accordance with modern IAEA recommendations general principles of estimation of radiation situation on radiation hazardous object in normal expluataion mode, conclusion of normal expluatation mode, or in accident mode exists. Practical methodology of safety case and tactics of monitoring of state of radiation hazardous object should rely not only on measuring, but also on model calculations and forecasts. Optimal tactics of monitoring includes definition of probabilistic picture of possible pollution different marine areas assuming hypothetical leak of pollutant with violation of defence barriers. One way of building such probabilistic pictures is execution of multi-variant calculations using long standing databases. Different calculations in multi-variant mode executes assuming different accident start time, in advance models multi-variant dynamic of marine area polluton. Not only maximum values of pollution to be interested, but and statistical estimations with different confidence levels (for filtration of rarery big values) for hypothetical leak of pollutant. In the base of the numerical algorithm of proposed technique lies Monte-Carlo method using lagrangian particles with non-zero sizes.
An effective algorithm of the numerical solution to the Stefan problem
Authors: Kurbatova Galina I. , Ermolaeva Nadezhda N.
Published: December 2019

The method of the frontal interval of the numerical solution to Stefan problems is proposed. The method allows the calculation of the position of the phase transition boundary with high accuracy at any of time. Using the example of a plane two-phase Stefan problem, which has an exact analytical solution, the advantages of the proposed method in comparison with a variable time stepping method are demonstrated with respect to the calculation of the position of the phase transition boundary. An example of the solution to the one-phase Stefan problem using the frontal interval method is also given.
The Balance-Characteristic Numerical Method on Triangle Grids
Authors: Gorbachev D Y , Goloviznin V M
Published: December 2019

In this paper we introduce new balance-characteristic method on triangle grids. We describe main steps of the algorithm on the two-dimensional shallow water equations. Method verified on basic test for shallow water equations with flat bottom and compared with the results of other authors.
Lagrange-Eulerian method for numerical integration of the gas dynamics equations: parallel implementation on GPUs
Authors: Khrapov Sergey , Khoperskov Alexander , Khoperskov Sergey
Published: December 2019

We describe a new CSPH-TVD method for numerical integration of hydrodynamical equations. The method is based on combined Lagrange-Euler approaches, and it has been devoted to simulations of hydrodynamical flows in various astrophysical systems with non-homogeneous gravitational fields and the non-steady boundary between gas and vacuum. A numerical algorithm was tested on analytical solutions for various problems, and a detailed comparison of our method with the MUSCL scheme is also presented in the paper. It is shown that the CSPH-TVD scheme has a second order of accuracy for smooth solutions (well-balanced approach) and it provides reliable solutions in the vicinity of strong shock waves and at the open gas-vacuum interfaces. We also study the effectiveness of parallel implementations of CSPH-TVD method for various NVIDIA Tesla K20/40/80, P100 graphics processors.
Numerical model for calculating displacements near a crack
Authors: Maksimova A.G. , Arakcheev A.S. , Lazareva G.G.
Published: December 2019

The paper presents a two-dimensional model of elastic deformations. An isotropic medium region in near a crack propagating along the surface is considered. The results correlate well with an analytical solution.
Thermal action of pulse radiation on the carbon conic shells loaded with internal pressure
Authors: Matveenko A M , Ostrik A V , Bakulin V N
Published: December 2019

The new mechanism of constructions destruction as a result of thermal action of radiations and particles fluxes was considered. It is supposed that interruption of construction operability comes owing to non-stationary processes of deformation and destruction. Non-stationary deformation and destruction take place as a result of action of quasi-stationary working loadings at saltatory change of construction rigidity. Jump of rigidity arises at volume and impact heating of material by means of action of radiations and particles fluxes.

A numerical method for predicting of the thermal and tension-strain states of thin-walled orthotropic constructions having variable thickness under the action of energy fluxes of different physical nature are considered. Physical and chemical processes in result of heating of composite construction materials were taken into account. These processes are the binder pyrolysis, chemical reactions of carbon and air flow components, and the ablation of carbon residue. Non-stationary processes occurring in the shell has been numerically simulated. Model of layer-by-layer destruction is used in this simulation.
Numerical solution of the inverse coefficient problem of filtration in a multilayer reservoir
Authors: Khairullin M. Kh. , Badertdinova E. R. , Khairullin R. M.
Published: December 2019

This work proposes a computational algorithm based on the regularization method for determining the hydraulic conductivity coefficient of a layered oil reservoir. The results of hydrodynamic investigations of vertical wells, opening a layered reservoir, are used as initial information.