bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fractal Interpolation and Integration over Two-Dimensional Triangular Meshes
Authors: Sarı Zekeriya , Kalender Gizem , Günel Serkan 
Published: December 2019

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Effective calculation of thermophysical properties of composite materials with multiple configurations by asymptotic homogenization technique
Authors: Grigoriev Vasiliy , Zakharov Petr , Akimov Mir 
Published: December 2019

Abstract
In this work a three-scale asymptotic homogenization technique is considered for calculating the thermophysical properties of composite materials with multiple periodic configurations. Heterogenieties of porous structures were considered by the periodic distribution of single cells at the microscale and mesoscale levels. Two effective thermal conductivity coefficients are calculated to obtain an average solution on the global structure. A three-scale algorithm is also compared with the classical two-scale homogenization, where microscale allows all heterogenieties. We provide a numerical experiments which show the efficiency and accuracy for the calculation of heat transfer of composite material with multiple configurations.
Scaling in Super Element Model of Petroleum Reservoirs
Authors: Mazo Alexandr , Potashev Konstantin 
Published: December 2019

Abstract
A feature of the super element two-phase flow model in an oil reservoir is the construction of a solution on computational grids with a spatial step of the order of the distance between wells (hundreds of meters) horizontally and of the order of the total thickness of the reservoir (tens of meters) vertically. To maintain the acceptable accuracy of the solution, the upscaling procedures are performed during the transition from a detailed geological to a large super element computational grid and downscaling during a reverse transition at the local refinement of the solution. The field of absolute permeability and functions of relative phase permeability are subject to upscaling. The downscaling procedure is applied to the grid saturation function on the super element grid to formulate the initial conditions for local refinement of the solution on the detailed computational grid. The paper describes ways to simplify and implement these procedures, taking into account the characteristic features of the geological structure and the process of oil reservoir development.
Finite-element modeling of critical loads of buckling of structures considering of nonlinearity of pre-buckling state
Authors: Repinskii V V , Bakulin V N 
Published: December 2019

Abstract
An approach is proposed to determine the critical loads of buckling, taking into account the geometric nonlinearity of the subcritical stress-strain state of structures. The first stage involves the structure strain-stress state in the context of geometrical non-linearity at some preset loading level. Afterwards the found solution neighborhood is supplemented with linearized non-linear equation system and the solution for the obtained linearized system is found. Following is the second linearization of the initial equation system in the linearized system solution neighborhood, obtained at the previous stage. The condition of equation systems degeneracy obtained after the second linearization causes a generalized eigenvalue problem. The approach is implemented using finite element models for the calculation of shell structural elements.
Analytical matrix solutions of linear ordinary differential equations with constant coefficients
Authors: Vinogradov Y I , Molchanov D B , Bakulin V N 
Published: December 2019

Abstract
The article puts forward a modified finite element method based on decomposition and analytical solution techniques. The algorithm is as follows. A complex structure is divided into simple form sub-regions which involve partial differential equations. Next, the equations are decomposed. The decomposed equation solutions are written using analytical solution formulae. Meanwhile, the finite element size of the method proposed is defined only by the value of an averaging interval of required functions, since ordinary differential equation formulae are analytical. The algorithm has been tested by solving rectangular plate and bicurved shallow shell bending problems. The results proved proper convergence to precise values with increasing number of finite elements.
Data space reflectivity full waveform inversion
Authors: Gadylshin Kirill , Tcheverda Vladimir 
Published: December 2019

Abstract
The full waveform inversion of seismic data aroused the hope to perform simultaneously and in automated way tomography and imaging by solving non-linear least-squares optimization problem. As it has been recognized early, brute force minimization by classical methods is hopeless if low time frequencies are absent in the data. The paper develops a reliable numerical technique for smooth velocity reconstruction via model space decomposition. We present realistic synthetic examples for validating presented algorithm.