bluuebunny/crossref_metadata_2025_split huggingface dataset:
Results of the study of the possibility of replacing the Gia GemSet, designed for evaluating the color of precious stones, with digital simulators for automated control systems
Authors: Kushkoeva A S , Chertov A N , Gorbunova E V , Veselov S V 
Published: February 2021

Abstract
Currently, the quality of precious stones is assessed by the organoleptic method. To identify their color experts use a set of Gia GemSet imitators made of transparent acrylic plastic-a polymer with a high refractive index, and with its own GIA color space. The authors conducted research on the optical characteristics of the GIA GemSet set in order to study the possibility of replacing physical standards with digital simulators for automated control systems. The research was carried out using two methods: spectral and technical vision. Spectral measurements were performed using a USB4000 fiber-optic spectrometer. To determine the color characteristics of digital images, we used a proprietary hardware and software package. Based on the research results, a color body of the GIA GemSet for the case of a standard D65 source is constructed, which gives a visual representation of the characteristics of the set. The correspondence between the color coordinates of the samples obtained by the two methods is established, which confirms the possibility of automation of color of precious stones evaluation process.
Photonic crystal structures based on submicron particles of polymethyl methacrylate
Authors: Nemtsev I V , Shabanova O V , Shestakov N P , Ivanenko A A , Cherepakhin A V , Ya Zyryanov V 
Published: February 2021

Abstract
Morphological parameters, reflection spectra, IR absorption spectra, and glass transition temperatures of submicron-sized spheres of poly(methyl methacrylate) (PMMA) formed in a water-acetone dispersion medium were studied in comparison with similar spheres obtained in distilled water. Dependence of a shrinkage degree of the submicrospheres on the concentration of acetone in water is studied. Features of the formation of periodic structures based on the water-acetone dispersions of PMMA in four different ways are considered. 2D (photonic crystal films) and 3D (artificial and inverse opals) resonance structures were obtained.
Digital model to optimize the rotor assembly for aircraft engine compressor models
Authors: Bolotov M A , Pechenin V A , Yu Pechenina E , Pronichev N D 
Published: February 2021

Abstract
The article focuses on the problems of knowledge-intensive products assembly quality in aircraft engine industry. A mathematical model has been proposed to determine optimal conditions for mating assembly units of a low-pressure compressor (LPC) rotor of an aircraft engine. Parameters optimized include relative angular positions of parts in the rotor. Three optimization criteria have been considered: assembly geometry; imbalance value and integral criterion combining both above criteria. The model has been implemented in the MATLAB system. The calculations have been made using actual part models created based on measurements of the LPC parts geometry. The best optimization criterion has been selected.
Decomposition of a System of Equations of Motion of a Spacecraft with a Considerable Asymmetry in a Rarefied Atmosphere
Authors: Lyubimov V V 
Published: February 2021

Abstract
We consider a system of equations simulating an uncontrolled descent of a spacecraft in a low-density atmosphere. The spacecraft is a solid body with a shape close to a solid of revolution. An important structural feature of the spacecraft is the presence of considerable geometric and aerodynamic asymmetry in its design. It should be noted that the initial system of equations of motion for the spacecraft is essentially nonlinear. In order to enable an effective asymptotic analysis of the evolution of motion of the spacecraft, it is necessary to decompose the initial system of equations of motion of the spacecraft. The aim of this study is to decompose the system of equations of motion of the spacecraft into two subsystems: slow-motion subsystem and fast-motion subsystem. The method of integral manifolds makes it possible to lower the order of the initial system of equations. The resulting slow subsystem can be represented in the form of a single-frequency system of equations with several slow variables. An important applied result of the study is the fact that the subsequent analysis of the evolution of slow variables in a slow subsystem can be performed using known asymptotic methods.
The optimal aircraft gas turbine engine control in low gas mode in the conditions of external additive noise
Authors: Novikova S V , Tutubalin P I , Snegurenko A P , Yakhina R R 
Published: February 2021

Abstract
The article is devoted to algorithm development to select an optimal control law of a gas turbine engine in the conditions of external additive noise and incomplete information regarding the values of control parameters. A step by-step algorithm for problem solving is given. The effectiveness of the algorithm is proved by numerical experiments.
Mathematical modeling of mass-heat transfer processes on the grain of a catalytic cracking catalyst
Authors: Uzyanbayev R M , Yusupova R R , Gizzatova E R 
Published: February 2021

Abstract
One of the most important processes ensuring deep oil refining both abroad and in Russia is the catalytic cracking process. This is the largest tonnage process of secondary oil refining and takes the second place in terms of the volume of processed raw materials after its primary distillation. The study of processes on the catalyst grain is necessary to create effective catalytic systems. The calculations of the chemical process on the catalyst grain are carried out on the basis of solving the equations of the mass balances of components and heat.
Synthesis of the optimal control law for the reorientation of a nanosatellite using the procedure of analytical construction of optimal regulators
Authors: Sinitsin L I , Kramlikh A V 
Published: February 2021

Abstract
The method is described in the article and an algorithm for the synthesis of the optimal control law for the reorientation of the nanosatellite using the procedure of analytical construction of optimal regulators is proposed. The algorithm provides a search of control for reorienting the nanosatellite along a phase trajectory close to the nominal one, subject to restrictions on the magnitude of the control torque. The nominal trajectory is divided into local sections, on each of which the required control is calculated.
3D computer-aided simulation of SHS macrokinetics in the Ni-Al porous medium with the closest packing of “mesocells”
Authors: Jordan V I , Shmakov I A , Grigoryevskaya A A 
Published: February 2021

Abstract
The paper discusses the methodological features of the procedure for simulation the SHS process in the “etalon” model structure of the closest packing of the so-called mesocells in the form of balls of the same radius. In the center of the mesocell there is a spherical Ni particle (radius R
Ni = 30 μm), around which aluminum particles of radius R
Al = 10 μm are contained in a spherical interlayer with a thickness of 20 μm. The etalon structure is formed by a program that takes into account the distribution of mesocells in the structure of the closest packing (alternating flat layers with square symmetry). The software has implemented the procedure for preparing the “calculation area” in the form of a three-dimensional grid of nodal points (3D Cartesian calculation grid with the same step h= 1 μm along the x, y, z coordinates), for which a 3D data structure Points[i][k][l] with several record fields was created. The record fields of the structure Points[i][k][l] are the following: T- temperature, η - depth of chemical conversion, type - type of material and etc. A technique for numerical solution of the heat conduction equation using an implicit scheme of bicyclic splitting based on the symmetric Krank-Nicholson scheme is implemented. Together with the bicyclic splitting scheme, a procedure is implemented for numerically solving the diffusion kinetics equation in mesocells. For computational speedup, the parallelization schemes of cycles are used, which determine the main time costs for performing “runs (sweep)” in the computing schemes. As a result of 3D simulation of SHS macrokinetics, sets of temperature profiles and time-varying relative radii (external boundaries) of intermetallic phase layers in mesocells are given.
Modification and training of the “ant algorithm” for planning swarm operations of moving object
Authors: Mostovoi Y A , Berdnikov V A 
Published: February 2021

Abstract
A swarm of mobile robots, as a system of relatively simple interconnected controlled objects, performs a common task simultaneously and in a distributed manner. When planning swarm operations associated with the creation in the service area through the frontal band of the zones of operation of the target equipment there is a need to consider the possibility of its operational regrouping, since at the time of planning the exact purpose of the swarm operation has not yet been determined, or is a secret, or is determined by a number of random circumstances. The execution of the swarm operation is advisable to carry out in two phases. The first phase starts even before the resolution of these uncertainties by creating a basic random network with a relatively small concentration of robots. In the second phase, after resolving the uncertainty, a programmable percolation route is formed by local rearrangement of the swarm objects, which provides a predetermined coverage of the target equipment of the robots with a certain service zone. A modified ant algorithm with evolutionary learning is considered in order to quickly solve the swarm problem of two-phase operation. In this case, you can significantly reduce the time for the operation.
Asymptotic stress fields near the crack tip in perfect plastic materials under mixed mode loading (plane strain conditions)
Authors: Stepanova L V 
Published: February 2021

Abstract
In the paper the asymptotic stress fields in the vicinity of the crack tip in perfectly plastic Mises materials under mixed mode loading for the full range of the mode mixities are presented. This objective is engendered by the necessity of considering all the values of the mixity parameter for the full range of the mode mixities for plane strain conditions to grasp stress tensor components behaviour in the vicinity of the crack tip as the mixity parameter is changing from 0 to 1. To gain a better understanding of the stress distributions all values of the mixity parameter to within 0.1 were considered and analysed. The asymptotic solution to the statically determinate problem is obtained by the eigenfunction expansion method. Steady-state stress distributions for the full range of the mode mixities are found. The type of the mixed mode loading is controlled by the mixity parameter changing from zero for pure mode II loading to 1 for pure mode I loading. It is shown that the analytical solution is described by different relations in different sectors, the value of which is changing from 7 sectors to 5 sectors. At loadings close to pure mode II, seven sectors determine the solution whereas six and five sectors define the solution for the mixity parameter higher 0.33 and less than 0.89 and higher 0.89 respectively for plane strain conditions. The number of sectors depends on the mixity parameter. The angular stress distributions are not fully continuous and radial stresses are discontinuous for some values of the mixity parameter. It is interesting to note that the characteristic feature of the asymptotic solution obtained is the presence of a segment of values of the mixity parameter for which the solution does not depend on the mixity parameter (the solution does not depend on the mixity parameter for the mixity parameter from 0.89 to 1 and the solution coincides with the solution for mode I crack in perfect plastic materials for plane strain conditions). Thus, the salient point of the study is that the asymptotic solution is described by the same formulae for all values of the mixity parameter from 0.89 to 1 for plane strain.
Modeling of onboard systems operation of small satellites based on general logical-probabilistic method
Authors: Salmin V V , Tkachenko I S , Volgin S S , Ivanushkin M A 
Published: February 2021

Abstract
An approach for simulating the operation of onboard systems of small satellites has been developed. The purpose of the technique is to simulate all possible combinations of malfunctions in the onboard systems of the small satellite, leading to the occurrence of abnormal situations during their operation. As a result of using the technique, a list of emergency situations is created, which is later used to create programs for complex testing of small satellite on-board equipment at the ground testing stage. The use of the technique leads to a reduction in time for the preparation of tests, provides support in making decisions on the management of the small satellites and reduces the response time to emergency situations that arise during operation.
Determination of the main design parameters of cost-effective remote sensing satellite systems at the stage of preliminary design
Authors: Salmin V V , Kurenkov V I , Safronov S L , Tkachenko I S , Yakischik A A , Ivanushkin M A , Volgin S S , Krestina A V 
Published: February 2021

Abstract
This article surveys approaches to the selection of design parameters and modelling the functioning of the remote sensing satellite systems, taking into account the requirements and restrictions on customer resources. The objective of this research is to increase the efficiency of the use of space systems to solve urgent tasks of monitoring the earth’s surface. Firstly, an analysis of the requirements for space imagery materials and consumer information support was carried out, secondly, mathematical models of remote sensing equipment and onboard systems of small spacecraft were developed, and finally, a database with the technical characteristics of the onboard systems and remote sensing equipment of spacecraft, launch vehicles and ground-based reception and processing information facilities was created. As a result, software to determine main design parameters and modelling the functioning of cost-effective remote sensing satellite systems was developed.
Efficiency of different separation elements for removal of fine particles from gas
Authors: Zinurov V E , Dubkova N Z , Popkova O S , Dmitrieva O S 
Published: February 2021

Abstract
A paper deals with the urgent problem of studying the separation process of gas flow from fine-dispersed particles. A device developed to intensify gas flow separation from fine-dispersed particles. The principle of operation of the device is given. The effect of the shape of separation elements, gas flow velocity, as well as size and density of particles on device efficiency, has been investigated. As a result of the study, the maximum efficiency of gas flow separation (on average 85%) is achieved at a gas velocity of 8 m/s. Moreover, the separation increases when the density and diameter of the particles begin to grow. The double-T shape of separation elements was demonstrated as the most effective type of geometry.
Naimark complements in the building of simplices
Authors: Novikov S Ya , Fedina M E 
Published: February 2021

Abstract
We define frames for a finite dimensional Hilbert space ℍ as the complete systems in ℍ. An equiangular tight frame (ETF) is an equal norm tight frame with the same sharp angles between the vectors. A regular simplex is a special type of ETF in which the number of vectors is one more than the dimension of the space they span. A detailed and independent from other sources presentation of recent results by M. Fickus, J. Jasper, E. J. King and D. G. Mixon is given, in which a lower bound for the spark of the system of equal norm vectors is obtained using the restricted isometry property. The existence of the regular s-simplices for an arbitrary positive integer s is proved using Naimark complement. A review of recent results towards resolving the known Paulsen problem is given.
On small perturbations of Markov cyber threat models
Authors: Magazev A A , Tsyrulnik V F 
Published: February 2021

Abstract
In this work, we consider Markov chain-based stochastic modeling of cyber threats acting on computer systems. In the framework of this approach, computer systems are considered as systems with failures and recoveries by analogy with technical system models in reliability theory. Under the assumption that the cyber threats are independent random events, we derive the explicit analytic formulas for the state probabilities of the corresponding Markov chain and the mean time to security failure (MTSF). Then we investigate the case of dependent cyber threats and derive the approximate expressions for the state probabilities and MTSF within the framework of the first-order perturbation theory. As an illustration of our results, we consider a few simple examples.
Decentralized square-root information Kalman filtering based on J-orthogonal transformations
Authors: Tsyganov A V , Tsyganova Yu V 
Published: February 2021

Abstract
The paper addresses the problem of decentralization of the measurement data processing based on matrix J-orthogonal transformations in the square-root information Kalman filter. J-orthogonal transformations are applied in a decentralized filter at the stage of communication and assimilation. The results of numerical experiments confirm the efficiency of the proposed solution. The developed algorithm can be used for measurement data processing in decentralized distributed computing networks.
Algorithm for detecting a change in the motion mode of an object moving along a complex trajectory
Authors: Golubkov A V , Tsyganov A V , Petrishchev I O 
Published: February 2021

Abstract
The present paper solves the problem of quick detection of a change in the motion mode of an object moving along a complex trajectory. The process of the object movement is described by a hybrid stochastic model. To solve the problem, a sequential probability ratio criterion is applied. A distinctive feature of the proposed algorithm is the ability to make decisions on a limited set of values of the likelihood ratio function. The results of numerical experiments confirm the efficiency of the developed algorithm.
Approximate analytical solution of the Graetz problem
Authors: Eremin A V 
Published: February 2021

Abstract
The study on velocity and temperature distribution in fluid flows is important both for the theory and practical applications. The design of efficient heat-exchange equipment, the development of heat and thermomechanical modes of product treatment, the determination of heat losses in the pipeline systems include the need to determine the velocity and temperature fields in fluid flows. The key aspects of the method have been considered with help of using the example of solving the Graetz problem for parallel and cylindrical channels.
It is shown that finding the solution to a partial differential equation with respect to the temperature function can be reduced to integrating an ordinary differential equation with respect to the new unknown function q(η) which is the law of temperature change in the center of the channel. The combined use of the heat balance integral method and additional boundary characteristics made it possible to obtain a simple in form analytical solution to the problem under consideration. It is noted that the accuracy of the solutions obtained depends on the number of approximations used, i.e. the number of terms of the approximating series.
When using only one term, i.e. already in the first approximation, the relative error of the method is not more than 8 percent in the range of the longitudinal coordinate change 0.1 ≤ η < ∞ and decreases to 4 percent in the second approximation. The analytical form of the solutions obtained provides analyzing the isotherms fields, calculating the average temperature, the Nusselt number, etc.
Numerical implementation of biological kinetics multi-species model in the Azov Sea
Authors: Sukhinov A I , Nikitina A V , Filina A A , Leontyev A L 
Published: February 2021

Abstract
Paper covers the research of biological kinetics processes based on a multi-species model of plankton and fish interaction of the Azov Sea at low and high size considering the V erhulst and Allee effects, competition for resources, taxis, catching, spatial distribution of biogenic matter and detritus. Discrete analogue of developed model problem of water ecology, included in a software complex, were calculated using schemes of increased order of accuracy considering the partial filling of computational cells. The system of grid equations of large dimension, arising at discretization, has been solved on the basis of a two-layer variational type method – the minimum corrections method having the maximum convergence rate. Effective parallel algorithms were developed for numerical implementation of biological kinetics problem and oriented on multiprocessor computer system and NVIDIA Tesla K80 graphics accelerator with the data storage format modification of. Due to it, the reproduction processes of biogeocenose populations have been analysed in real and accelerated time.
XXIst Century Perspectives on the Micro & Macro Worlds
Authors: Mimouni J 
Published: February 2021

Abstract
We present a broad perspective on our (Early) XXIth century understanding of both the macro and micro worlds, and whether the dream embodied in the symbolism of Glashow’s snake (Ouroboro) has been implemented to some degree or recessed away. Do we have a unified vision of the world at those extreme scales? What about the status of that «21st century» theory «that fell accidentally into the 20th century.” aka superstrings to quote E.Witten, and which is the «ideological» cement of very powerful aspiring-to-be paradigms like Cosmic Inflation, Multiverses, extra dimensions (ED) … as well as the inspiration of most pre-Big Bang theories. We will discuss along the way the fine tuning curse, the Cosmic Inflation and Multiverse’s Pandora box, and other big mysteries perhaps of our own making, and propose that in our search for «truth», and to keep our sanity in the actual jungle of bold «new ideas» and puzzles, we be guided by the voice of reason which goes by the unpretentious name of under-determinacy of theories.
Lessons from supersymmetric black holes
Authors: Messamah I , Van Den Bleeken D 
Published: February 2021

Abstract
This paper studies the D4-D0 system in light of black hole puzzles. The properties of its microstates, that live in the associated quiver quantum mechanics [1, 2], are discussed. It is shown that the pure Higgs states of these quivers satisfy the needed properties to be (part of) the microstates of a single centered D4-D0 black hole.
Interacting Chaplygin gas cosmology
Authors: Bensaid A , Bouamrane R 
Published: February 2021

Abstract
In this paper, we study in FRW universe the interaction between the viscous Chaplygin gas and the dark energy in the modified gravity theory F(R,T), where T and R are the trace of the energy-momentum tensor and is the Ricci scalar respectively. In this model, the universe is dominated by both components Chaplygin gas and dark energy. We discuss the effect of the bulk viscosity on the dark energy state parameter, this study was carried for two interactions after obtaining the modified Friedmann equations. Finally, we found that both interaction models lead to quintessence phase of the dark energy.