bluuebunny/crossref_metadata_2025 huggingface dataset:
One way for calculating the interaction of flow with an elastic surface with nonlinear parameters
Authors: Shvab I V , Nimaev V V
Published: December 2019

In the paper we discuss a biomechanical model of microcirculation and transcapillary metabolism and present a mathematical model of metabolic processes occurring in microcirculation level. We conside the following interrelated processes: the flow of blood (a non-Newtonian fluid) in capillaries; filtration and reabsorption of fluid through the wall of the arterial capillary into the surrounding tissue and from this one back to the venous capillary; the movement of fluid in the interstices, the exchange of substances between the interstitial fluid and tissue cells, drainage into the lymphatic capillaries. Biological tissue is modeled as a porous, resilient, isotropic matrix or frame saturated with a fluid of the same type. It is believed that the liquid is contained in the pores of the matrix. The study of microcirculation allows you to better understand the complex interlinked processes of metabolism in the body, identify the causes of pathologies and suggest possible treatment interstitium.
Phase Transition in 2D Ising Model with Next-Neighbor Interaction
Authors: Kryzhanovsky Boris , Litinskii Leonid
Published: December 2019

We used a Monte Carlo method to analyze a planar Ising model taking into account a ferromagnetic interaction with next neighbors. We found that independent of the value of the additional interaction, the character of singularity of the heat capacity did not change. Namely, at the critical point the heat capacity has a logarithmic singularity. We obtained a semi-theoretical formula relating the value of the critical temperature with the value of the additional ferromagnetic interaction.
Fdm solution of mhd flow in a rectangular duct with slipping and partly insulated partly conducting side walls
Authors: Arslan Sinem , Tezer-Sezgin Münevver
Published: December 2019

The magnetohydrodynamic (MHD) flow of an electrically conducting fluid is considered in a long channel (pipe) of rectangular cross-section in which the fluid is driven by a pressure gradient and the flow is steady, laminar, fully-developed. The flow is influenced by an external uniform magnetic field applied perpendicular to the channel-axis. Thus, the velocity field

V
→

and the magnetic field

B
→

have only channel-axis components V and B on the cross-section of the channel which is a rectangular duct. The finite difference method (FDM) is used for solving the governing equations with the boundary conditions which include both the slipping and variably conducting side walls. The well-known characteristics of the MHD flow including the slipping velocity are observed. Thus, the FDM enables one to depict the effects of Hartmann number, conductivity and slip parameters on the behavior of both the velocity of the fluid and the induced magnetic field at a small expense.
Numerical 3-d model experiments on global climate sensitivity to solar constant variations
Authors: Parkhomenko V P
Published: December 2019

The aim of the study is to show an important role of the solar radiation flux in positive feedback “temperature - surface albedo” during the transition to glaciation regimes observed in the history of the Earth. The study is based on a three-dimensional hydrodynamic global climate coupled model, including ocean model with real depths and continents configuration, sea ice evolution model and energy - moisture balance atmosphere model. A series of numerical experiments were carried out to assess the impact of changes in solar radiation flux on the global climate. It is assumed that the solar constant gradually decreases discretely compared to the current value and in each case is determined the steady climatic mode. Simulation period is about 2000 years. Gradual increase in the sea ice area and a catastrophic increase at the end of stage 3, when the oceans are completely covered with ice (so called “snow ball Earth”) are get. These results are naturally explained by the presence of the “temperature decrease - glaciation” positive feedback. The stage 3 maximum surface air temperature is -30° C, the minimum -80°C. Strong temperature and ice cover changes lead to significant changes in the horizontal and vertical thermohaline ocean circulation. The vertical thermohaline circulation has the weakened horizontal velocities in the north direction in the ocean upper layers and increased in the direction of the equator in the deep layers (in contrast to the present situation). The author was supported by the Russian Foundation for Basic Research (project no. №17-01-00693).
Concept of instrumentation of digital twins of nuclear power plants units as observers for digital NPP I&C system
Authors: Volodin V.S. , Tolokonskii A.O.
Published: December 2019

The relevance of the idea under consideration lies in the development of the use of digital twins of power units in the nuclear industry. With their help, we can not only predict the state of technological equipment, etc., but also solve the problem of parameter tuning of automatic regulators in different operating modes of NPP unit. Authors consider approaches to this problem based on optimal control theory, fuzzy logic and machine learning. Advantages and disadvantages of each approach are considered.
Mathematical modelling the interaction of laser pulse with substance for the tasks of proton therapy
Authors: Echkina Eu. , Guzminova N
Published: December 2019

In this paper, we discuss using laser plasma as a source of high-energy ions for the purposes of hadron (proton) therapy. Hadron therapy (HT) is a modern, high-precision form of radiation therapy that uses protons to irradiate diseased tissue. HT has received the greatest use for the fight against cancer. The high accuracy of cancer cell damage, together with the gentlest impact on healthy organs and normal tissues, the absence or mild side effects, make proton therapy indispensable where the tumour is located next to the vital organs, in paediatrics, where the anatomical location of the tumour makes it impossible for surgical removal and use of photon therapy will place the patient at an unacceptable risk. In our work we present the results of mathematical modelling of laser pulse with substance. Computer modelling gives the chance of selection of parameters of a laser pulse and target, for more exact focusing of a pulse and obtaining the set energy of ions.
Computer simulation of the process of magnetic reconnection in the vector configuration
Authors: Echkina Eu. , Inovenkov I
Published: December 2019

Computational simulation of processes or magnetic reconnection an play an important role of studying of laboratory and space plasma. 3D nonlinear magnetohydrodynamic llow us to more accurately describe such phenomena as the current layer, solar flashes, solar wind, magnetic islands in the tokamak. Here we demonstated the results of computer simulation using the parallel algorithm of process of the magnetic reconnection in 3D magnetic configuration.
A Numerical Study of a Modular Sparse Grad-Div Stabilization Method for Boussinesq Equations
Authors: Demir Medine , Kaya Songül
Published: December 2019

This study presents a modular sparse grad-div stabilization method for solving the Boussinesq equations. Unlike the usual grad-div stabilization which produces fully coupled block matrices, the proposed stabilization method produces block upper triangular matrices. Thus, the proposed method is more attractive in terms of both its computational cost and solution accuracy. We provide unconditional stability results for velocity and temperature. Two numerical experiments are performed to demonstrate the efficiency and accuracy of the method.
Fluctuation and evolution of research topics
Authors: Huang Ding-wei
Published: December 2019

We study the shift of global research interests from 1985 to 2016. We consider the 252 research areas in Web of Science and analyse the temporal variation of their rankings. In the last three decades, science dominates over both social sciences and humanities in the high ranks. The average ranking of science continues to rise. In contrast, a decline is observed in both social sciences and humanities. A widening gap is noted between science and humanities. The shift of research interests can be observed in the continuing change of similarity between two distributions from different years. However, the Lorenz curve remains stationary in the last thirty years. The 70/30 rule can be applied, where 70% of annual publications can be attributed to 30% of research areas.
Investigation of dynamics of the IBR-2M pulsed reactor with energy-production up to 1200 MW·day
Authors: Pepelyshev Yu.N. , Popov A.K. , Sumkhuu D.
Published: December 2019

The operation of the IBR-2 pulsed reactor (1987-2006) showed that a total transfer coefficient of the power decreases during the operation of the reactor, therefore each reactor cycle has its own transfer coefficients [1] and stability margins. Hence, the study of dynamics of the new reactor IBR-2M (modernized version IBR-2, since 2011) is extremely important. In this paper, the results of an experimental and a modelling study of dynamics of the IBR-2M are presented, for the reliable and safe operation of reactor. For this purpose, model dynamics of the IBR-2M has been developed, which includes experimental data on reactor feedback parameters in period 2015-2017 at a mean power of 0.5 MW. Using the model dynamics of the IBR-2M, the stability margins of the reactor in different regimes its operation (self-regulating and automatic regulating) were estimated. It shown that during the analyzed time of the operation reactor with energy production up to 1200 MW·day significant changes in dynamics of reactor has not occurred. The reactor has been working in the stability region.
Advances in the project of the gravitational signal generator device to measure the speed of gravity
Authors: Souza M. A. , Coppedé D. , Frajuca C. , Bortoli F. S. , Santos G. A. , Nakamoto F. Y.
Published: December 2019

This work shows the latest improvements in the geometry of the quadrupole mass of a gravitational signal generator device, which should be used in an experiment to measure the speed of gravity. This device must generate a tidal gravitational signal with a frequency of 3200 Hz. The gravitational wave detector Mario Schenberg, developed in Brazil, is the first option as the detector of the signal. The previous steps of the project are briefly discussed, and the new FEM (finite element modeling) simulation for the quadrupole mass is shown. An analysis of the mechanical stresses produced at high speed rotation is presented. The new FEM simulation yields a favorable geometry for the inclusion of the magnetic suspension of the quadrupole mass. The results indicate the feasibility for the continuation of the project and subsequent construction of the real device.
Soliton surfaces induced by the coupled integrable dispersionless equation with self-consistent sources
Authors: Shanina Z. , Myrzakulov R.
Published: December 2019

The coupled integrable dispersionless equations have a signi cant interest because of structure, integrability, and the possibility of obtaining a soliton solution. In this paper, we construct soliton surfaces for integrable dispersionless equation with self-consistent sources in Riemann space. The surfaces, arising from M-XXXII equation and their reduction in R
3, are studied. We obtain Gaussian and mean curvatures and also evaluate the area of surface parametrically de ned with the Riemannian metric. Using the scale transformation and transformation of dependent and independent variables of the coupled dispersionless equations we obtain the equation that describes a current-fed string interacting with an external magnetic eld in three-dimensional Euclidean space.
Soliton surface associated with the WDVV equation for n = 3 case
Authors: Zhadyranova A.A. , Myrzakul Zh.R.
Published: December 2019

This paper describes the soliton surfaces approach to the Witten-Dijkgraaf-E.Verlinde-H. Verlinde (WDVV) equation. We constructed the surface associated with the WDVV equations using Sym-Tafel formula, which gives a connection between the classical geometry of manifolds immersed in R

m
and the theory of solitons. The so-called Sym-Tafel formula simplifies the explicit reconstruction of the surface from the knowledge of its fundamental forms, unifies various integrable nonlinearities and enables one to apply powerful methods of the soliton theory to geometrical problems. The soliton surfaces approach is very useful in construction of the so-called integrable geometries. Indeed, any class of soliton surfaces is integrable. Geometrical objects associated with soliton surfaces (tangent vectors, normal vectors, foliations by curves etc.) usually can be identified with solutions to some nonlinear models (spins, chiral models, strings, vortices etc.) [1], [2]. We consider the geometry of surfaces immersed in Euclidean spaces. Such soliton surfaces for the WDVV equation for n = 3 case with an antidiagonal metric η11 = 0 are considered, and first and second fundamental forms of soliton surfaces are found for this case. Also, we study an area of surfaces for the WDVV equation for n = 3 case with an antidiagonal metric η11 = 0.
Neural net clustering in the study of electrical grids failures in relation to geomagnetic storms
Authors: Siluszyk A , Gil A , Modzelewska R , Moskwa Sz , Siluszyk M , Wawrzynczak A
Published: December 2019

Nowadays, the space weather issues are of a great importance, especially, for all satellites operators or ground-based electrical and electronic systems caused by geomagnetic storms. In spite of many studies on the changeable Sun and the fluctuations in the interplanetary space triggered by solar-driven disturbances, the question, which of the components of geomagnetic storms influence the strongest the electrical and electronic systems is still open. Here, we consider the data of electrical grids breakdowns having unidentified reasons, as well as failures connected to the aging of the infrastructure elements and breakdowns of electronic devices, which occurred during the periods of an increased geomagnetic activity. Mathematical and statistical methods, among them neural net clustering, demonstrate that there exist connections between the groups of the coefficients characterizing the state of Earths vicinity during magnetic storms and the number of failures in electrical network.
Reduced directional coupler through the use of artificial cells
Authors: Letavin Denis A.
Published: December 2019

This paper presents the topology of the directional coupler that carries out the power division of 1 to 3. The area of the proposed device was reduced by 72.5% due to the use of artificial cells, whose characteristics are equivalent to quarter-wave segments, with smaller dimensions. Using the NI-AWR Environment 14 program, the topology of the proposed device was developed, with an operating frequency of 1 GHz and on the FR-4 material. Then, using a photolithography, a prototype of the coupler was made and its characteristics were measured using a R&S vector network analyser.
A Novel Simple Miniaturization Technique for Microstrip Couplers
Authors: Letavin Denis A. , Mitelman Yuriy E. , Chechetkin Victor A.
Published: December 2019

This paper analyzes the new compact design of couplers based on the use of microstrip lowpass filters. The proposed design achieves significant reduction in coupler size while obtaining the same characteristics as of the conventional coupler. Prototype of the coupler with the central frequency of 1 GHz was produced on the substrate with dielectric permittivity of 4.4. The experimental results showed good agreement with numerical simulations. The size of the rat-race coupler was reduced by 83.7%.
Distribution of ionization and tunneling times in a model of strong field ionization
Authors: Lunardi José T. , Manzoni Luiz A.
Published: December 2019

We consider a simple model for strong field ionization and use the Salecker-Wigner-Peres clock to obtain a distribution of (real) times associated with this phenomenon. By coupling the Salecker-Wigner-Peres clock to the particle in different regions, we are able to distinguish between the ionization (exit) time, the tunneling time and the time the particle spends in the well before entering the barrier (the well time). We show that the distribution of ionization/exit times, which are the times usually measured in attoclock experiments, may differ significantly from the distribution of tunneling times, suggesting that the ionization times cannot be generally interpreted as tunneling times.
Application of the random matrix theory to vibrational properties of amorphous solids
Authors: Conyuh D A , Beltukov Y M
Published: December 2019

In this work, we apply the random matrix theory to the study of vibrational properties of disordered systems with a big number of degrees of freedom, such as amorphous solids. Mechanical stability of amorphous solids implies the Wishart ensemble with the positive definite dynamical matrix of the form

M
^

=

B
^

B
^

T

. The translational invariance in amorphous solids leads to the sum rule Σ
i

Bij
= 0, which means non-zero correlations of the matrix elements Bij
. The proposed correlated Wishart ensemble has many universal properties of amorphous solids. One of these properties is the boson peak in the reduced vibrational density of states g(ω)ω
2. The boson peak has been observed in many experiments on amorphous solids, but its nature was not clear so far. We show that the boson peak naturally occurs in the proposed model and find its analytical form.
Evaluating the connectivity, continuity and distance norm in mathematical models for community ecology, epidemiology and multicellular pathway prediction
Authors: Allaerts W
Published: December 2019

The main global threats of the biosphere on our planet, such as a global biodiversity impairment, global health issues in the developing countries, associated with an environmental decay, unnoticed in previous eras, the rise of greenhouse gasses and global warming, urge for a new evaluation of the applicability of mathematical modelling in the physical sciences and its benefits for society. In this paper, we embark on a historical review of the mathematical models developed in the previous century, that were devoted to the study of the geographical spread of biological infections. The basic notions of connectivity, continuity and distance norm as applied by successive bio-mathematicians, starting with the names of Volterra, Turing and Kendall, are highlighted in order to demonstrate their usefulness in several new areas of bio-mathematical research. These new areas include the well-known fields of community ecology and epidemiology, but also the less well-known field of multicellular pathway prediction. The biological interpretation of these abstract mathematical notions, as well as the methodological criteria for these interpretative schemes and their corroboration with empirical evidence are discussed. In particular, we will focus on the boundedness norm in polynomial Lyapunov functions and its application in Markovian models for community assembly and in models for cellular pathways in multicellular systems. Finally, the usefulness of hybrid mathematical modelling in miscellaneous biological, environmental and public health issues will be discussed.

.
Mathematical model of the motion of suspended particles in a turbulent flow and their influence on the motion of an unmanned aerial vehicle
Authors: Shalabayeva Bakyt , Jaichibekov Nurbolat , Kutpanova Zarina , Toleu Altynbek
Published: December 2019

A mathematical model of turbulent motion of a non-homogeneous flow is constructed. Based on the pulsation energy balance method, a closed system of equations is obtained for calculating the average velocity and turbidity of a non-uniform flow. The calculation of the pulsation characteristics of the flow with a transverse shift is carried out and the analysis of the effect of the impurity on the pulsation structure of the turbulent flow and its effect on the motion of an unmanned aircraft is carried out. Since the safety assessment and service lifetime of an unmanned aerial vehicle cannot exclude the influence of disturbances in the atmosphere when calculating characteristics.
Simulation of disruptions triggered by Vertical Displacement Events (VDE) in tokamak and leading edge effect in plasma energy deposition to material surfaces
Authors: Atanasiu Calin V. , Zakharov Leonid E. , Li Xujing
Published: December 2019

The paper describes two major non-linear properties of the vertical instability of a tokamak plasma, which has a vertical elongation: (a) inductive excitation of surface (edge) currents stabilizing the instability and converting it into fast equilibrium evolution, and (b) creation of a wetting zone without the normal component of the magnetic field when the plasma has contact with material surfaces. Two major disruption effects for both mitigated and non-mitigated disruptions, important for JET and ITER, were considered: (a) excitation of vertical disruption during the current quench (i.e., abnormal plasma current ramp down) and (b) related to the wetting zone, potential leading edge effect in plasma energy deposition to the in-vessel tiles during disruptions. Our considerations together with a 2-D version of the VDE (Vertical Disruption Event) code are based on a new mathematical model, called Tokamak MHD (TMHD), as a replacement for the conventional model, a model that cannot solve numerical problems related to extreme plasma anisotropy and negligible mass. The code includes a 3-D model of surface currents on a thin conductive wall and has a well-specified algorithm for extension to vertical disruptions that excite asymmetric kink modes.
Use of Robotic Simulation in the training of Nursing Students of the Faculty of Health Sciences: Perceptions
Authors: Romero A , Valderrama D , González J D
Published: December 2019

Clinical simulation is rapidly becoming an important tool in the training of students who pursue a career in nursing as a viable complement or a substitute for practice with living patients. Although simulation can never replace real clinical practice, it is a useful tool to create realism before performing practical skills during patient care. Robotic simulation can create real scenarios that not only test knowledge, but also provide a safe environment for practicing advanced concepts and difficult patient situations. Members of the nursing faculty often have the challenge of preparing nurses for complex environments and working with interdisciplinary teams. In addition, health care administrators expect a basic competency from new nursing graduates who are prepared to function in the complex work environment independently after orientation. An exploratory and descriptive study was conducted using surveys among the students of the nursing program on the use of a humanoid robot for teaching nursing in the laboratory of practices of the Magdalena University. The results of this study indicate that, in the program and students are positively motivated about the use of technology as a teaching strategy (especially humanoid robots), which suggests a greater exploration of its use in education Nursing.
Boss Tower and Baseplate Flange Optimization
Authors: Bamrungwong Joompon
Published: December 2019

The swaging process is commonly used in head stack assembly, which is a process that is undertaken to either reduce or increase the diameter of tubes or rods. In the head stack assembly process, a swage boss engages with an arm hole of E-Block. Current hard disk drives have very small tolerances, requiring the swage effect of new hard disk drives to be reduced to as little as possible. In this study, finite element analysis (FEA) was used to reduce the swage effect. At present, FEA and investigative tests indicate that a significant portion of gram changing through swaging is caused by E-block tip deformation due to swaging. Deformation of the E-block tip is the result of unbalanced swage forces between the tension and compression suspension. Achieving optimization concepts leads to a new swage plate design to reduce the gramload change of the target and to equalize the swage forces. The FEA results found that gramload change of the target decreased by 35% on the tension side, and by 65% on the compression side through swage by boss tower. The HGA torque out was not different. The suspension flange was also studied. Subsequently, suspension manufacturing is able to bias the suspension as incoming HGA. The flange deformation might be closer to zero after the swaging process.
Simulation of motion of satellites after fixing the values of their accelerations
Authors: Mazitov K D , Yushkov M P
Published: December 2019

At the Department of Theoretical and Applied Mechanics of the Faculty of Mathematics and Mechanics of St. Petersburg State University [1] the theory of motion of nonholonomic systems with linear nonholonomic constraints of high order n<2 was created. The high-order constraints are considered as program and ideal ones, and their reaction force is considered as the required control force. A consistent system of differential equations with respect to unknown generalized coordinates and Lagrange multipliers is constructed to solve the problem. The report examines the motion of Soviet satellites of the systems “Cosmos”, “Molniya”, “Tundra” after fixing the values of their accelerations in apogees. This corresponds to imposing the nonlinear second-order nonholonomic constraints on the further motion of satellites [2, 3]. The equations of constraints are differentiated in time and presented as linear third-order constraints to make it possible to apply the above theory. The motions of satellites are studied in polar coordinates, the origin of this system coinciding with the center of the Earth. It turns out that after fixing the acceleration values in the apogees, the satellites begin to rotate between two concentric circles, alternately touching each of them.
Reduction of inhomogeneous boundary conditions to homogeneous in partial differential equations
Authors: Oblakova T.V.
Published: December 2019

A universal replacement of the variable is proposed, which allows reducing the problem with inhomogeneous boundary conditions of any type to a problem with homogeneous ones. It is shown that due to this replacement the structure of the obtained analytical solutions is significantly simplified. The question of the existence of such a replacement is investigated, examples are given that demonstrate the performance and advantages of the proposed approach for solutions obtained by the Fourier method.
Software Environment for Computer-Aided Heuristic Optimization of Hydraulic Systems for Synchronous Movement of Actuators of Various Functional Purposes
Authors: Bushuev A Yu , Ivanov M Yu , Korotaev D V , Resh G F
Published: December 2019

A software environment was developed for computer-aided design of optimal throttle hydraulic synchronization systems of actuators of various functional purposes operating under conditions of external alternating-sign force effects. The criterion of an optimization procedure was the minimization of a mismatch time of relative movement of actuators during operation. A compute core of an object-oriented code was constructed on the basis of a dynamic mathematical model of a synchronization system consisting of four power cylinders. A model problem was solved with the help of the created software environment. This model problem demonstrated the efficiency of the proposed multidimensional optimization process. The methodology was based on the use of the well-known heuristic method (binary coded genetic algorithm) and the subsequent improvement (in the sense of a given objective functional) of the obtained solution by a method on the basis of the Hooke-Jeeves algorithm. Recommendations on the practical application of the software and mathematical support for achieving the best convergence to the extreme value of a vector of controlled parameters were formulated.
Model of the polarization extinction ratio change due to multiple reflection of laser radiation from the faces of the terbium-gallium garnet crystal in Faraday rotator
Authors: Seleznev A V , Ivanov G Y , Kogut E V , Shaidulin R I , Ryabushkin O A
Published: December 2019

In this work we investigated the phenomena in the Faraday rotator, that can affect the polarization state of transmitting laser radiation. We considered two factors that can cause deterioration of radiation extinction ratio and, therefore, isolation properties of Faraday cell: multiple reflections of radiation from the faces of the TGG crystal and imperfection of the laser beam input relative to the central axis of the crystal. We were able to calculate the impact of these factors on polarization extinction ratio of laser radiation transmitting through the crystal.
Fractal Interpolation and Integration over Two-Dimensional Triangular Meshes
Authors: Sarı Zekeriya , Kalender Gizem , Günel Serkan
Published: December 2019

The fractal interpolation techniques are powerful alternatives to classical interpolation methods in case of complex irregular data such as financial time series, seismic data and biological signals. The main goal of this study is to apply fractal interpolation techniques over two-dimensional irregular meshes. We partition the polygonal interpolation domain into triangular regions and consider affine contraction mappings from triangular regions to triangular patches of the mesh. Calculation of the fractal interpolation coefficients is reduced to solving a linear system of equations. Freely chosen scaling variables of the iterated function system transformations provide flexibility. Additionally, the constructed iterated function system coefficients for the interpolation can be used directly to evaluate two-dimensional numerical integrals over the domain. We provide basic error results via numerical simulations.
A self-consistent model of second harmonic generation of laser radiation in the periodically poled nonlinear-optical crystal conditioned by its nonuniform heating
Authors: Ivanov G Yu , Cherpak P S , Konyashkin A V , Ryabushkin O A
Published: December 2019

We introduce a self-consistent model that describes the process of the second harmonic generation (SHG) of the laser radiation in a nonlinear-optical crystal in conditions of its nonuniform heating induced by optical absorption. A periodically poled crystal pumped by the pulse laser radiation focused into its center was considered. The iteration procedure of solving the SHG problem relies on the interrelated solution of two equation systems describing the temperature dependent SHG and the heat conduction processes. The heat sources are represented by the absorbed power of both pump and generated radiations. Along with the absorption of pump and generated waves the diffraction effect was also taken into account. Eventually the resulting distribution of the crystal temperature should correspond to the radiation intensity distributions of pump and second harmonic.
Contact symmetries and conservation laws of the first order of the equation of one-dimensional shallow water over a rough bottom in Lagrange’s variables
Authors: Aksenov Alexander V , Druzhkov Konstantin P
Published: December 2019

The systems of equations of one-dimensional shallow water over a rough bottom in Euler’s and Lagrange’s variables are considered. The problem of group classification of contact symmetries of the shallow water equation in Lagrange’s variables is solved. First order conservation laws of the shallow water equation in Lagrange’s variables obtained using the Noether’s theorem. Bottom profiles, providing additional conservation laws, are given.
Equations that Describe Waves in Tubes with Elastic Walls and Analysis of Numerical Methods for Reversible and Weakly Dissipative Systems
Authors: Bakholdin I. B.
Published: December 2019

Models of tube with elastic walls are presented: with controlled pressure, filled with incompressible fluid, filled with compressible gas. The non-linear theory of hyperelasticity is applied. The walls of a tube are described with complete membrane model. Equations are solved numerically. General approach for calculation of non-dissipative and weakly dissipative systems is given. Three-layer time and space centered reversible numerical scheme and similar two-layer space reversible numerical schemes with approximation of time derivatives by high-order Runge-Kutta methods are analysed. A method of correction of numerical schemes by inclusion of terms with high-order derivatives is developed. Additional terms with high-order derivatives my be included also in order to calculate non-dissipative and dissipative shocks at the same time.
Simulation of process of small satellites separation from deployer installed on cargo spacecraft
Authors: Bogomolov N V , Anfalov A S , Borzykh S V , Bakulin V N
Published: December 2019

A possible way to launch CubeSats is to place them in deployers installed on Progress MS cargo spacecraft. Launching satellites into orbit is potentially feasible both during Progress MS autonomous flight and during its stay in the International Space Station. In order for the CubeSats to achieve their mission targets, the separation process requires that they obtain the necessary linear velocities, the angular disturbances obtained be minimized and that the satellites continue to move without collisions. Addressing these issues involves the development of a dynamic model based on the numerical integration of motion equations. Once the model has been verified, taking into account, in addition to the permissible mass-centric and inertial characteristics of the objects, the contact interactions of satellites with the deployer guide rails and the door, a series of statistical calculations are carried out for different launch scenarios, based on the results of which a conclusion about the possibility of implementing the schemes considered is drawn and recommendations are made (in terms of dynamics) on the choice of the most appropriate layout.
The search algorithm for discrete mode of electron plasma
Authors: Gordeeva N M , Yushkanov A A
Published: December 2019

The question about the shielding of external electric field electron plasma is examined. The search algorithm for discrete modes of electron plasma have been described. The case of arbitrary degree of degeneracy of the electron gas have been considered. Special attention is paid to the case when the degree of degeneracy of the electron gas is large. Have been demonstrated an effective way of finding the discrete mode in this case.
Mathematical modeling of creep and viscoplastic flow of a cylindrical layer material
Authors: Kovtanyuk L V , Panchenko G L
Published: December 2019

Within the framework of a mathematical model of large elastoplastic deformations, taking into account viscous properties of materials, a boundary value problem of creep and viscoplastic flow of a material in the gap between two rigid coaxial cylindrical surfaces under rectilinear motion of the inner surface is considered. Irreversible deformations accumulate from the beginning of the deformation process and are initially associated with the creep process of the material, which is described using the Norton creep power law. With a subsequent increase in the speed of movement of the inner cylinder at some time point, the stress state will reach the yield surface and a viscoplastic flow will begin in the material. As a plastic potential, we use the Tresca yield criterion, generalized in the case of taking into account the viscous properties of the material. The viscoelastic deformation, the emergence and development of the viscoplastic flow under uniformly accelerated motion of the inner surface, the flow under constant speed, and the flow inhibition under equal slow motion of the surface to a full stop are considered. Stresses, reversible and irreversible deformations, displacements are calculated, stress relaxation after the complete stop of the cylinder is investigated.
Simulation of the fracture of materials and structures under dynamic loads using parallel computing
Authors: Radchenko Pavel , Batuev Stanislav , Radchenko Andrey
Published: December 2019

The present work suggests algorithm enabling to describe adequately fracture of materials and structures under impulse loadings. The methodology of reconfiguration finite element mesh with re-computation of concentrated masses in nodes is considered. The algorithm uses all the capabilities of modern parallel computing to the full extent and can be easily scaled for all possible objectives. Numerical methodology demonstrates good qualitative and quantitative comparison with the experimental data.
Method of Finite Bodies for Mathematical Modeling of the Stress-strain State of Cylindrical Orthotropic Shell with the Reinforced Rectangular Hole
Authors: Revenko Victor P. , Bakulin Vladimir N.
Published: December 2019

An analytical-numerical method (nite bodies) for calculating the stress state of the cylindrical orthotropic shell with a large reinforced rectangular hole is proposed. The shell and reinforcement consist of various materials. The systems of equations that exactly satis es the equilibrium equations of the orthotropic cylindrical shell and the orthotropic reinforced are used. The presentation of the solution is divided into basic and self-balanced states. The nite-body method uses the conditional partition of the three-connected surface of the shell and the reinforcement into simpler doubly-connected and simply connected parts. An algorithm is developed for analytic-numerical solution of boundary-value problems, based on the proposed universal method of reducing the satisfaction of all contact conditions of shell parts and boundary conditions to minimization of the generalized quadratic form. We establish criteria under which the construction of approximate solution coincides with the exact one.
Mathematical Simulation of local transfer for non-Newtonian uid in porous fabrics
Authors: Dimitrienko Yu.I. , Li Shuguang
Published: December 2019

Many processes in the polymer composite, textile, food, and pharmaceutical industries are associated with the flow of non-Newtonian fluids in porous media. This paper considers the mathematical model of a multi-scale process for the filtration of non-Newtonian fluid in periodic porous fabrics. The model should be based on a three-dimensional Navier-Stokes equation with non-Newtonian Carreau-Yasuda viscosity using the asymptotic averaging method. A numerical algorithm was developed for solving local problems of non-Newtonian fluids in periodic cells, and the distribution of velocity, pressure and non-Newtonian viscosity in a single pore was obtained. The algorithm for calculating the permeability tensor is developed, and the effects of fluid rheology are also highlighted.
The time reversibility property in analysis of sound points in balance-characteristic difference methods
Authors: Afanasiev N A , Goloviznin V M
Published: December 2019

A new computational technology of flux-type variables calculation on new time layer is introduced for the balance-difference methods for solving quasilinear hyperbolic systems of PDEs. The proposed method allows to build a scheme, which is locally implicit in the sound points and explicit in all other nodes of the mesh. It also has the second order of approximation in time and space and the property of time reversibility if the flux correction procedure is disabled. Results of test computations for the problem of transonic dam-break are presented.
CUDA UNIFIED MEMORY ACCELERATION OF THE PROCESS OF DEVELOPING MULTI-GPU APPLICATIONS
Authors: Gorchakov A Y , Solovjev A V
Published: December 2019

The experience of using Cuda Unified Memory technology to develop Multi-GPU applications is described. The paper deals with the method of transferring computations on the MGDS-GPU model two-dimensional problem described by the equations of single-layer shallow water with variable density over an uneven bottom. To solve the problem was applied balance - characteristic scheme “CABARET”. The minimum steps necessary to go from computing on the GPU to computing on the MULTI-GPU are given. The computational efficiency is investigated depending on the size of the grid.
Application of non-stationary gas dynamic functions for mathematical modeling of gas dynamic processes
Authors: Grishin Y A , Bakulin V N
Published: December 2019

At numerical calculations of non stationary flow in extended channels with use of basic provisions of disintegration of discontinuities method noticeable acceleration of calculations gives application of specially developed non-stationary gas dynamic functions from Mach number. At the same time the greatest advantages of these functions’ application is shown during recording of boundary conditions. Here they are applied in a combination with the known functions of a steady flow as at disintegration of discontinuities, the idea of quasi-steady flow between the waves which passed and reflected from a boundary condition is used. By means of the program complex developed on the basis of non-stationary and stationary functions a number of practical tasks, in particular, of the organization of dynamic pressurization of the piston engine was solved.
Verification of the Cabaret schemes for the shallow water equations based on the conservation of angular momentum
Authors: Goloviznin V.M , Solovjev A.V , Zalesny V.B
Published: December 2019

To solve the problems of large-scale dynamics of the atmosphere and the ocean, a system of single-layer two-dimensional shallow water equations on a sphere is often used [1, 2]. Such a system is the basis for solving complete baroclinic systems of prognostic equations and is used to assess the accuracy and efficiency of computational algorithms for solving direct and inverse problems. Important issues here are the choice of a suitable form of writing differential equations and effective algorithms for their numerical solution.

In [3], instead of using the equation for the conservation of momentum in a spherical coordinate system, the authors proposed a technique based on the use of the equation for the conservation of angular momentum in a Cartesian coordinate system. This technique allows us to get rid of the degeneracy of the coordinate system near the poles, while preserving only two equations of motion. The semi-discrete finite-volume scheme written in [3] should be supplemented with a method for determining flows on the edges of a grid. The authors used the Cabaret technique [4] for this purpose, which ensures time reversibility on flows where the characteristics of one family do not intersect.

This paper presents the original shallow-water equations in an integral form, a semi-discrete finite-volume scheme, and a brief description of the closure of this scheme using the Cabaret technique. The main attention is paid to the verification of the scheme on a series of traditional tests.
An algorithm to identify text marked in rock core pictures with machine learning algorithm
Authors: Bai Yunfeng , Berezovsky Vladimir
Published: December 2019

The aim of our project is to extract numerical descriptors or gather feature of rock samples from their images made under microscope with computer vision algorithm which can overcome the bottleneck of traditional method. It is impossible to solve it without getting the imformation of microscope magnification of images when they were made. That is why this paper is about an algorithm to identify the text used to mark microscope magnification information in rock core sample pictures. This is a sub project. As locations of text in these pictures are not fixed, font of text is not fixed, font size of text is not fixed, a method of two steps is designed to identify the text from the background. It works as follows: first, find the location of text; second, recognize the text with Convolution Neural Network. Experimental results demonstrate the potential value of the proposed approach to identify the magnification information in rock core sample pictures and to apply as a funtion to a program of our future project.
Solution of two-phase nonisothermal fluid flow problem with nonlinear filtration law on heterogeneous computing systems
Authors: Tsepaev A V
Published: December 2019

The work is devoted to the methods of solving two-phase fluid flow problems in the reservoirs. It is assumed that in domain with high velocities Darcy’s law is violated and a nonlinear filtration law is used. To determine the temperature use the law of conservation of energy (first law of thermodynamics). The temperature of the fluid and of the skeleton are considered the same. The fluid viscosities are taken by the temperature functions. The methods for solving two-phase flow problems in porous medium with a nonlinear filtration law based on the decomposition methods are proposed. The proposed methods are implemented on the heterogeneous computing systems.
High Throughput Calculations as an Elevator on the Way from Chemical Structure to Novel Materials
Authors: Yushina I.D. , Makarov G.I. , Matveychuk Y.V. , Bartashevich E.V.
Published: December 2019

Development of new materials and drugs presently requires trial chemical methods that are time consuming and that depends on the chance more than we would have liked. We aim to describe, how the high throughput calculations can be applied for computational predictions of the organic crystalline structure and its properties. In this work we tried to illustrate the examples of techniques that were applied to accelerate the design of iodine-contained organic materials with nonlinear optical properties, to explain the plasticity of maleate amino acids crystals by means of analysis of hydrogen bonds orientation, to clarify the biological activity of traditional antibiotics using molecular dynamics modeling
Multiscale simulation of the heat and mass transfer with Brinkman model
Authors: Alekseev Valentin , Vasilyeva Maria , Vasiliev Vasily
Published: December 2019

In this work, we consider a heat and mass transfer problem in heterogeneous media. Mathematical model is described by a system of equations for temperature, pressure and velocity. For simulations of the flow problem in domain with low permeable obstacles, we use a Brinkman model. Fine grid approximation is constructed based on the discontinuous Galerkin (IPDG) method for heat transfer and flow problems. For coarse grid approximation of the flow problem, we use a Generalized Multiscale Discontinuous Galerkin Method. Numerical results are presented for a two-dimensional model problem with different number of the multiscale basis functions.
Quasi-cellular nets based models of flow systems
Authors: Aristov Anton O.
Published: December 2019

It considered specific type of discrete structures quasi-cellular nets (designed by author). The basic idea is space division to discrete areas cells, which distributed through the directions of flows in different subject areas (transport, industry, social systems, life systems etc.). Each cell has computer memory view as data structure that consists of data about cell coordinates, flow object, and changeable parameters of cell. Distribution of flow being considered as transition of flow between neighboring cells. Quasi-cellular nets are models that will be use for implementation of flow dualism (micro- and macrolevel of simulations) for different subject areas.