bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of a continuous process of isoprene polymerization in the presence of titanium-based catalyst systems under polycentric conditions
Authors: Miftakhov E , Mustafina S , Petrenko V , Podvalnii E 
Published: May 2020

Abstract
In the research is represented the mathematical model of the periodic process of isoprene polymerization in the presence of titanium-containing catalyst systems. By the process of constructing of the mathematical model was taken into account the polycentric nature of the applied catalytic system. On purpose of organization of the possibility to describe a continuous process in a cascade of ideal mixing reactors, the mathematical model was supplemented by the corresponding hydrodynamic mechanism. For the resulting system of differential equations, a numerical solution method was programmatically implemented and was conducted a computational experiment to predict the main molecular characteristics of the resulting product.
Modern and future schemes of very-high cycle fatigue tests
Authors: Nikitin A , Stratula B , Volkov B 
Published: May 2020

Abstract
The development of a new piezoelectric fatigue machine operating in pure torsion is presented in this paper. The proposal for implementation of a testing machine to research on very-high cycle fatigue at biaxial bending is studied. Results of pure torsion tests on titanium alloy VT3-1 processed by forging and extrusion are shown. Evaluations of specimens shapes made of aluminum alloy D16T and titanium alloy VT3-1 were conducted as well as the possibility to conduct VHCF bi-axial bending tests was confirmed.
Uniqueness of solving the problem of transport and sedimentation of multicomponent suspensions in coastal systems
Authors: Sukhinov AI , Sukhinov AA , Sidoryakina VV 
Published: May 2020

Abstract
The present work is devoted to the study of three-dimensional model of transport and sedimentation of suspended matter in the coastal zone. The model takes into account the following processes: advective transport due to the movement of the aquatic environment, microturbulent diffusion and gravitational sedimentation of particles of the suspension, and changes in the geometry of the bottom caused by sedimentation of the suspension or the rise of bottom sediments. The aim of the work was to conduct an analytical study of the uniqueness of the initial-boundary-value problem corresponding to the constructed model. In accordance with the stated aim, an initial-boundary-value problem is considered for a parabolic type equation with lower derivatives in the domain for which a quadratic functional is constructed and the uniqueness of the solution is proved by the energy method.
Modelling of suspended particles motion in channel
Authors: Sukhinov Alexander I , Chistyakov Alexander E , Kuznetsova Inna Y , Protsenko Elena A 
Published: May 2020

Abstract
The paper considers the application of the scheme based on linear combination of the Upwind and Standard Leapfrog difference schemes with weight coefficients obtained by minimizing the approximation error. The proposed difference scheme has shown its effectiveness in solving diffusion-convection problems in the range of grid Peclet numbers 2 ≥ Pe ≥ 20, which allows us to apply this class of schemes for the numerical solution of computational Oceanology problems. The problem of soil dumping was considered as a practical example of application of the proposed schemes.
Mathematical modeling of hydrophysical processes for water with complex bottom geometry
Authors: Sukhinov A I , Chistyakov A E , Leontyev A L , Nikitina A V , Filina A A 
Published: May 2020

Abstract
The paper covers the development and research of computational structure for mathematical modelling of hydrobiological processes for water with complex bottom geometry, based on the modern information technologies and computational methods. The models used in modelling take into account following: microturbulent diffusion; gravitational settling of pollutants; plankton populations nonlinear interaction; the salinity impact, temperature. The scheme with weights was proposed for discretization of the developed model, that allowed significantly reduce the error and the computational time. Practical significance of the work is that the proposed model was software implemented; the limits and prospects of its use were defined. The experimental software was designed on the basis of a graphics accelerator for mathematical modelling of possible development scenarios of the waters with complex bottom geometry, taking into account the environment influence. Parallel implementation was performed using the decomposition methods for computationally labours diffusion-convection problems taking into account the CUDA architecture characteristics.
Development and approbation of the improved CART algorithm version
Authors: Demidova L A , Usachev P O 
Published: May 2020

Abstract
This article considers the classification problems using the decision trees. It suggests the improved CART algorithm version called clean CART (CCART). The key feature of this algorithm is the reducing of the hardware memory for the tree storing. The main ideas of the CCART algorithm software implementation have been presented. The experimental results of comparison of the original and the presented algorithms for constructing the decision trees confirm that the proposed CCART algorithm has the stated advantage. Therefore, the proposed CCART algorithm is recommended for use in the ensembles of classifiers construction.
Classification of cardiac arrhythmia using machine learning techniques
Authors: Firyulina M A , Kashirina I L 
Published: May 2020

Abstract
Cardiovascular disease is one of the leading causes of death worldwide. Currently, there is an increase in the percentage of people with various heart rhythm disorders. There are permanent (chronic), persistent and paroxysmal form of atrial fibrillation, and the most severe violation is the permanent form. Since the reasons for the development of a certain form of atrial fibrillation are not completely clear, this article presents an analysis of various characteristics that affect the formation of arrhythmias of these species. The most significant signs that can potentially be predictors of different forms of the disease have been identified. Four machine learning methods were used for the analysis: classification trees, logistic regression, random forest, and gradient boosting. The highest cross-validation accuracy was obtained using logistic regression.
On some class of nonlinear mean random values
Authors: Khatskevich V L 
Published: May 2020

AbstractIn this paper we study the properties of one class of nonlinear means, including a geometric mean, a harmonic mean, and also a power mean of random variables. The considered random variables are assumed to be positive and have finite mathematical expectations. The asymptotics and extremal properties, as well as algebraic properties and inequalities between means are also studied below.
Computer simulation of the sensory interaction of carbon nanotubes with various modifications in relation to alkali metal atoms
Authors: Boroznina Natalia , Zaporotskova Irina , Boroznin Sergey , Bakhracheva Yulia 
Published: May 2020

Abstract
The performed theoretical studies obtained by computer modeling and calculations performed by the semi-empirical method using the MNDO calculation scheme showed the possibility of creating sensitive chemically active probes, which are semiconductor sensor systems with boundary modification, which can act as the tip of the cantilever of the atomic force microscope. These studies allow us to predict that such a sensor based on a modified borocarbon nanotube will react to the presence of ultra-small amounts of substances, which opens up prospects for its use in the field of chemistry, biology, medicine, etc. The use of chemically modified nanotubes, including in atomic force microscopy, is the way to create probes with distinct chemical characteristics.
The development of V. V. Strygin’s ideas in numerical mathematics in the works of Samara mathematicians
Authors: Blatov I A , Dobrobog N V , Kitaeva E V 
Published: May 2020

Abstract
The article reviews the most important results in the field of numerical mathematics obtained by Professor V. V. Strygin’s disciples and the disciples of his disciples in 2000–2019 in the city of Samara. We present the results on spline interpolation of functions with a boundary layer, methods and algorithms for a posteriori adaptation of computational grids for singularly perturbed boundary value problems and the results on applied wavelet analysis based on spline wavelets.
Differential systems stability analysis based on matrix multiplicative criteria
Authors: Bulanov S G 
Published: May 2020

Abstract
This article proposes a method of stability analysis in the sense of Liapunov for systems of ordinary differential equations. The method is based on matrix multiplicative stability criteria obtained from transformations of numerical integration difference schemes. Criteria are formed in the form of necessary and sufficient conditions. A distinctive feature of the criteria is that they do not employ the methods of the qualitative theory of differential equations. Specifically, for the case of linear systems, the evaluation of characteristic numbers and characteristic indicators is not necessary. When analyzing the stability of nonlinear systems, the construction of Liapunov functions is not required. Matrix multiplicative form of the criteria allows computerization of stability analysis. The software implementation of the criteria is performed in real time and, based on its results, allows to make an unambiguous conclusion about the nature of stability of the system under study.
Analysis of the nature of features of heat and mass transfer in discrete bulk of food products
Authors: Voronenko B A , Leu A G , Abushinov E V , Yukhnik I P 
Published: May 2020

Abstract
Despite the importance of resolving issues related to predicting the formation of heat-moisture fields during storage of grain, seeds and bulk-stored roots and tubers and the changes in technological properties of food raw materials that depend on them, currently, the mathematical descriptions of these associated phenomena do not suffice. This is due to the complexity and poor knowledge of the storage processes for bulk-stored food products at both the micro and macro levels. Such masses are a system with distributed parameters. In this regard, the possibility of predicting the fields of heat and moisture content depends, on the one hand, on the completeness of the necessary information about the moisture and temperature of the components of the mass at the initial moment, and on the other hand, on the reliability of the mathematical model capable of describing the real processes of heat transfer in bulk based on this information, which is used to set boundary conditions and thermophysical constants. An analysis of the nature of the features of heat and mass transfer in a discrete bulk of food product can be carried out only on the basis of the developed analytical models. This is the subject of this paper.
The residual plastic strain distribution over elastic–viscous–plastic cylindrical shell length upon longitudinal impact on the face
Authors: Egorov M V 
Published: May 2020

Abstract
This work is devoted to the study of the distribution of residual plastic strains on outer and inner surface over the length of a cylindrical shell in the process of dynamic deformation generated by a longitudinal impact on its end face. As a mathematical model, the Timoschenko’s model was used to describe the dynamic deformation of elastic thin shells, modified for the case of plastic deformations using the Bingham’s model. As the boundary conditions, we selected a longitudinal impact applied at the end face of the shell with longitudinal strains constant in time. As a method for solving the resulting system of differential equations in partial derivatives of a hyperbolic type, the third–order ray method was implemented. The paper represents options for the numerical calculation of the distribution of residual plastic strains for various thicknesses, as well as the corresponding shell shape after unloading.
The cybernetic concept of multialternativity in the evolution of biological systems
Authors: Podvalny S L , Vasiljev E M 
Published: May 2020

Abstract
The article describes the results of mathematical simulation and quantitative analysis of the biological property of diversity. The purpose of this work is a methodological generalization of this wildlife property in the form of a cybernetic concept of multialternativity as an evolutionary strategy of functioning of complex systems. The process of mathematical simulation of evolutionary processes in a complex hierarchical ecosystem with the closed-loop trophic cycle is carried out on the basis of the differential equations of mass balance. Several substantive principles given in the conclusions formulate the concept of multialternativity, i.e., the principles of multilevelness, division of functions and discretization. The constructive nature of these principles opens the way to a practical realization of a strategy of multialternativity in the creation of complex control systems realizing various functions.
Mathematical modeling of axisymmetric flow of granular materials
Authors: Frolov A L , Frolova O A , Sumina R S , Sviridova E N 
Published: May 2020

Abstract
A mathematical model of the axisymmetric flow of cohesive granular materials is considered. A plastically compressible material is considered as a mathematical model. This material has an additional characteristic - its own rotation of particles. The existence of this characteristic leads to the asymmetry of the stress tensor and the presence of torque stresses. Asymmetric components of the stress tensor are balanced by normal pressure due to the presence of rolling friction. It is shown that the distinctive characteristic of the axisymmetric state is the layering of its flow. The condition for the flow of cohesive bulk material is obtained.
Experimental studies and multi-factor analysis of the fuel component distributions over the mixing head nozzles of the liquid rocket engine
Authors: Kretinin A V , Milenin A V , Popkov A N , Shmatov D P 
Published: May 2020

Abstract
A model device of the liquid rocket engine mixing head for experimental determination of hydraulic non-uniformity of fuel distribution is described. Schemes of hydraulic and gas-dynamic test benches are given. The results of the planned factor experiment to determine the array of flow rates through individual sprayers are presented. Neural network regression factor models were created to evaluate the criterion of non-uniformity. The influence of various factors on the parameters of non-uniformity is estimated
Mathematical modeling of rotating disk states
Authors: Semka E V , Artemov M A , Babkina Y N , Baranovskii E S , Shashkin A I 
Published: May 2020

Abstract
We consider the problem of a rapidly rotating disk in the elastic-plastic state. The piecewise linear plasticity condition in general form is chosen. It is believed that all plastic curves have the common point of intersection which corresponds to uniaxial tension. For external parameters, we obtain the conditions that determine the probability of inception of plastic zones. It is shown that plastic zones could incept in the center of the disk and/or on the boundary of it. The problem in the plastic zone is statically determinate. The case when the plastic zone occupies some central part (core) of the disk, where one regime of plastic condition is fulfilled, is considered. In order to estimate the stress state inside the elastic zone of the disk, equivalent stress which is equal to the chosen plasticity function is defined. In order to define the relationship between plastic deformations and stresses, the piecewise linear plastic potential being equal to the plasticity function is chosen. The plastic incompressible body is considered. The associated flow rule can be integrated so that the problem of getting displacements turns into quasistatic one. The problem of determining displacements in the plastic region leads to a first-order differential equation with respect to the radial component of the displacement vector. Therefore the continuity condition for displacements at the elastic-plastic boundary and the assumption that the displacements in the center of the disk are equal to zero leads to an overdetermined problem. So, only the continuity condition for displacements at the elasto-plastic boundary is accepted. It is assumed that plastic deformations at the elastic-plastic boundary are equal to zero. It is shown that displacements at the center of the disk are equal to zero automatically for all piecewise linear conditions of plasticity apart from the Tresca yield criterion. For the Schmidt–Ishlinskii yield criterion, all deformations at the center of the disk attain finite values. Meanwhile, for other piecewise linear conditions, plastic deformations at the center of the disk attain infinitely large values. This explains the discontinuity of displacements at the center of the disk for the Tresca yield criterion. The calculation results are presented as graphs of stresses, displacements, and deformations.
Modeling of dynamic branching of a longitudinal shear crack at an inclusion
Authors: Bogomolova T G , Verveyko N D , Shashkin A I , Bykova M I , Krupenko S E 
Published: May 2020

Abstract
Mathematical modeling of branching of the leading edge of a longitudinal shear crack on a porous inclusion is proposed. The leading edge of the crack is approximated by the δ-neighborhood of the plastic deformation of the material with the front of longitudinal or shear waves, at which the longitudinal or transverse velocities break when passing through the leading edge of the crack. Expressions are obtained and graphs of the relative intensity of the leading edges of the reflected cracks of longitudinal and transverse shear and the conditions for the generation of reflected cracks depending on the angle of intersection of the crack with inclusion and physical parameters of the material are constructed.
The analysis of the laminar-turbulent transition onset for the Poiseuille flow in the flat channel with the velocity profile periodic background perturbation
Authors: Kolodezhnov V N 
Published: May 2020

Abstract
The paper adopts an approach to predicting the laminar-turbulent transition onset, which is based on the hypothesis of a threshold “connection” of the transverse viscosity factor and the subsequent transverse velocity components “generation”. In the framework of this approach, certain empirical local transition conditions are proposed and imposed on the dimensionless invariant complexes that characterize the laminar flow under study. Based on these conditions, an analysis of the Poiseuille flow transition onset in the flat channel in the presence of the stationary velocity field periodic background perturbation is carried out. A comparison with the known experimental data is presented.
On the separation of two meteoroid fragments of different shapes
Authors: Lukashenko V T , Maksimov F A 
Published: May 2020

Abstract
Separation of two meteoroid bodies is studied using modelling method based on a system of grids and solving adjoint aerodynamic and ballistic problems. Bodies of the same mass but different shapes were considered. Calculations were done for different combinations of the cylindrical bodies with their cross sections having a shape of square, elongated rectangular and circle. Initially the bodies were placed near each other on the line perpendicular to the flight direction. The lowest value of separation velocity was obtained for the bodies with circular cross section; the separation velocity is significantly increased for the bodies with elongated rectangular cross section due to rotation. Stable aerodynamic position of the bodies with elongated cross sections occurs when the bodies fly with a large side perpendicular to the flight direction. The lateral velocity acquired by each body appears to be primary determined by its own geometry and show no dependency on the shape of a neighboring body.
Nonlinear effects at elastic deformation of cubic materials
Authors: Sokolova Marina , Khristich Dmitrii , Artyukh Ekaterina , Afanasova Olga 
Published: May 2020

Abstract
A variant of the relations of nonlinear elasticity is considered for anisotropic materials which are supposed to be crystals of cubic syngony with respect to the type of elastic symmetry. The proposed model takes into account the physical nonlinearity in the behavior of such materials under the condition of small deformations. Based on the representation of the elastic potential in the form of a tensor polynomial in third-order strains, relations for stresses with elastic constants of the second and third orders are obtained. On the basis of the concept of the elastic eigenstates of materials, in the case of a cubic material, representations for the elastic tensors of the fourth and sixth ranks in eigentensor bases are obtained. The proposed variant of constitutive relations takes into account the mutual influence of the processes occurring in various eigenspaces of cubic material.
Mechanical interaction of a reinforced concrete slab and a steel beam in bridge spans
Authors: Kozlov Vladimir A , Kozlov Alexey V 
Published: May 2020

Abstract
The paper aims to clarify the rules of calculation of steel-reinforced concrete bridge superstructures on the basis of generalization of modern scientific achievements in conjunction with the possibilities of computational software and computer technology in the field of calculations of multi-component sections without the need to use simplifying hypotheses that affect the accuracy of the calculation. An algorithm for calculating continuous multi-span beams of bridge structures with the possibility of taking into account the flexibility of the shear joint between concrete and steel structural elements is proposed, which increases the accuracy of determining the stress-strain state (SSS) of the structure. The results of the work can be used in the design of steel-concrete bridge superstructures. The significance of the work lies in the fact that the proposed analytical dependences in the joint use of modern computing power will clarify the calculation of steel-concrete bridges, thereby increasing the level of reliability of bridge structures, laid at the design stage.
Forced vibrations of beveled non-circular conical thin-walled structures of variable thickness
Authors: Kozlov Vladimir A , Chernikov Andrey V 
Published: May 2020

Abstract
The stress distribution in shells of variable thickness must be taken into account when designing various elements of general and transport engineering, aviation, rocket and space technology, structures. The paper presents one of the possible approaches to the dynamic calculation of a thin-walled non-circular conical structure rigidly fixed along a beveled end section. The resolving system of ordinary differential equations was obtained in the framework of the technical theory of shells using the variational Lagrange principle. The boundary-value problem of determining dynamic stresses in the structure under consideration under the influence of a harmonic load is solved numerically by the method of orthogonal sweeping of a system of linear ordinary differential equations of the first order. In contrast to the known works, a variable thickness of the structure along the length is considered.
Predicting the risk of road pavement premature destruction
Authors: Ermoshin N A 
Published: May 2020

Abstract
The paper reveals the ideas of assessing the road condition on the basis of risk theory, which allows predicting the rate of the road structure destruction and its actual life. The regularities of the influence of physicomechanical parameters of road construction materials, as well as the coefficient of variation of the required modulus of elasticity of the subgrade on the value of the equivalent modulus of elasticity and the rate of destruction of pavement are established.