bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approximate methods for H-infinity output feedback control
Authors: Panteleev A V , Yakovleva A A 
Published: September 2020

Abstract
The problem of finding Hm - regulators in the linear output control problem is considered. Sufficient IT -control conditions for closed loop control law depending on the state vector are formulated. Two approaches for approximate synthesis of the output feedback control systems are proposed. The first is associated with finding a pseudo-solution of the linear model of measuring system as well as with its use in control, the second one - with the synthesis of a state observer generating an estimate of the state vector and its application in control. The step by step algorithm is presented. It is shown that both of suggested methods provide the desired quality of transient processes and asymptotic stability in the model example. The approximate methods could be applied in autopilot design problems for aircrafts and rotorcrafts.
Trajectory Optimization of a Lunar Direct Landing from Halo-Orbits
Authors: Ivanyukhin A V , Korolevskiy E D , Starchenko A E 
Published: September 2020

Abstract
This paper illustrates the problem of optimizing the trajectory of a direct landing from a halo orbit to the lunar surface with given coordinates. The study is considered in circular restricted three body problem. The descent operation consists of two stages: change in velocity for descent from orbit (the descent is considered as an instantaneous change in velocity of a spacecraft) and the main stage of braking, which is considered as a task of optimal performance of the spacecraft with finite thrust. The formulation and solution of the optimal control problem is presented, as well as numerical examples illustrating the accessibility of various regions of the lunar surface and examples of landing trajectories.
Experimental study for stochastic pulse component of emission from stationary plasma thrusters in the radio-frequency range
Authors: Vazhenin N A , Plokhikh A P , Popov G A 
Published: September 2020

Abstract
This paper is a sequel to the authors’ publications devoted to the investigation of characteristics of self emission from electric propulsion thrusters. We consider the possibility of using the applications of the analytical signal theory and of the Fourier transform with a sliding window to study the spectral-temporal structure of the stochastic pulse component of the emission from stationary plasma thrusters in the radio-frequency range.
Colloid thrusters. Development status and prospects for application
Authors: Nigmatzyanov V V , Obukhov V A , Popov G A , Svotina V V 
Published: September 2020

Abstract
The article examines the principle of operation, the basic laws of electrostatic spraying of fluid, which constitutes the working process of colloid thrusters (CT). The features of two competing technologies for producing charged colloids based on the design of capillary type sprayers and the design of porous sprayers are considered. The experience of CT development and application is considered.
On the exoplanet obliquity variations in planetary four – body problem with evolving satellite’s orbit
Authors: Krasil’nikov P S 
Published: September 2020

Abstract
The evolution of the obliquity (the axial tilt) of a hypothetical exoEarth under the influence of gravitational moments from a star, a planet’s satellite in evolving orbit, and an outer exoplanet Evolution was investigated analytically. The exoEarth is assumed to be rigid, axially symmetric and almost spherical. The case where the orbits of two planets and satellite are given Keplerian ellipses while the satellite’s ellipse evolves on the lunar type was considered. The canonical equations describing the oscillations of spin axis of exoEarth were obtained. These equations contain one parameter (the longitude of the ascending node of the satellite’s orbit) slowly changing in time. Using the theory of the adiabatic invariant, approximate formulas for the precession angle and obliquity in time are obtained.
The problem of forecasting Earth pole trajectory when changing the average parameters of its motion
Authors: Perepelkin V V , Rumyantsev D S , Yan Soe Wai 
Published: September 2020

Abstract
The change of the Earth pole motion modes based on few-parameter two-frequency model has been investigated. It is shown that the effect of the change in the average frequency during the period of the Chandler and annual harmonics modulation leads to the change in the average parameters of the two-frequency model of the Earth pole oscillations. A method is proposed for detecting this effect by analyzing the phase variations of the observed Earth pole’s modulation.
A Godunov-type method for a multi-temperature plasma with the tabulated equation of state
Authors: Aksenov Alexey G 
Published: September 2020

Abstract
A multi-temperature code for a multi-component gas dynamic is considered. The velocities of components with nonzero mass are assumed to be identical to each other. The gas dynamic part is a Godunov-type method based on the efficient approximate solution of the Riemann problem operating with all components of the gas mixture. The method assumes the arbitrary table equation of state, but the system of the hydrodynamic equations should be hyperbolic. An arbitrary equation of state (EOS) can contain domains with a negative square of the sound speed c
2 = (dP/dρ)
a
at phase transitions. In that domains the gas enthalpy should be corrected to provide the nonnegative sound speed square. This work contains the test of the method on a strong shock wave in hydrogen plasma.
Packaging and unfolding of shells using highly elastic joints
Authors: Pestrenin V M , Pestrenina I V , Rusakov S V , Gilev V G , Buzmakova G V 
Published: September 2020

Abstract
A computational-experimental method for studying the packaging and unfolding of shell structures made of composite material is proposed. The construction consists of rigid elements interconnected by elastic hinges made of uncured prepreg. This material is elastic and therefore it can store an elastic energy during the structure packaging, and later a stored energy will facilitate unfolding. The hinge’s material is modelled by a hyper elastic isotropic medium, the Neo-Hookean potential is applied. The parameters of the potential are determined by the computational-experimental method. The viscous and viscoelastic characteristics of the binder are determined by the rheological method with a Physica MCR 501 rotational rheometer. The calculated effective properties of the hinge’s material are used to demonstrate the packaging of the cylindrical shell. Three different packaging methods for a cylindrical shell with six prepreg hinges are considered. The article studies the dependence of the load required for packaging on the type of packaging and the curing degree of the binder.
Effect of ablation at the inlet of submerged nozzle on discharge characteristics
Authors: Kirillova A N , Sabirzyanov A N 
Published: September 2020

Abstract
The effect of ablation on the discharge characteristics of solid rocket engines with submerged nozzles is examined. State-of-the-art computational fluid dynamics software package ANSYS Fluent is employed for simulation. The ablation is considered from the standpoint of the effect caused by uniform blowing of degradation products on the boundary layer developing over the entrance length of the submerged nozzle. Different masses of injected substance are considered. The impact of injection on velocity profiles is estimated. The discharge coefficient is affected by the non-isothermal boundary layer when degraded thermal protection material is injected and chemical reactions are neglected. The effect of injection on the profiles of velocity and temperature, and hence, on discharge characteristics is revealed.
Development and application of combined methods to expand the potential for predicting the defining characteristics of composites
Authors: Gusev E L , Bakulin V N , Chernykh V D 
Published: September 2020

Abstract
The issue of promising ways to expand potential opportunities for improving the effectiveness of methods for predicting the remaining life, durability, and reliability of composite materials and structures under the influence of extreme environmental factors is considered. Modifications of methods for searching for the global extremum of multiparametric functions have been developed and studied, taking into account the structural peculiarities of the efficiency criteria used in forecasting the remaining life and durability of structures made of composite and polymer materials. One of the promising ways to increase the potential opportunities has been analyzed. It is connected with the improvement of methods for constructing optimal directions for searching for the absolute minimum of efficiency indicators related to solving the problems of predicting the determining characteristics of polymer composites under the influence of extreme environmental factors and operational loads.
Methodology for processing expert judgments based on fuzzy weighted summation
Authors: Sudakov V , Sivakova T 
Published: September 2020

Abstract
The paper is devoted to the development and research of a new technique for fuzzy ranking of alternatives. The authors of this approach suggest dividing the criteria space into fuzzy preference areas. A criterion for the proximity of fuzzy preference ratings is also formulated. The scientific novelty of the proposed approach lies in the proposed procedure for clarifying the level of preference based on fuzzy weighted summation, for alternatives with close fuzzy levels of preference. The solution of the problem in this statement makes it possible to increase the distinguishability of alternatives by preference. Two approaches to the construction of membership functions of fuzzy preferences were investigated: the first method - choosing the type of membership function and then entering the parameters of the membership function; the second method is entering the characteristic points of the membership function and constructing a piecewise polynomial approximation. After entering preferences and presetting, this method allows ranking an arbitrary number of alternatives in a mode close to real time. In cases of high dimensionality of the vector criterion and optimized parameters of the domain model, as well as in the presence of complex algorithmic rules, the solution of such problems is of high scientific importance. In the public domain at http://ws-dss.com one can use this method - fuzzy ranking based on preference areas. The proposed approach was implemented (tested) on the problem of selecting an electronic pilot tablet.
Structure of a viscoplastic fluid flow in a pipe with a given obstruction shape
Authors: Ryltsev I , Shrager G 
Published: September 2020

Abstract
In this paper, we present a study of the axisymmetric steady-state laminar flow of a viscoplastic fluid in a pipe with variable cross section. Mathematical formulation of the problem is written in terms of stream function and vorticity variables in a cylindrical coordinate system. Rheological behavior of the medium is described by the Shvedov-Bingham model. Coordinate transformation is carried out to implement a numerical algorithm. The problem is solved numerically using the finite-difference method and the false transient method. This paper demonstrates the effect of Reynolds number, Bingham number, and geometric parameters of a flow domain on the flow structure.
Stability of the flow with an over-compressed detonation wave in a duct of variable cross section
Authors: Egoryan A J , Valiyev Kh F 
Published: September 2020

Abstract
The stability of stationary flows of an ideal gas in ducts of variable cross section with an over-compressed detonation wave is studied. The combustible mixture before the wave and the combustion products after it are perfect gases. A numerical-analytical method has been developed to analyse the stability of stationary flows with over-compressed detonation waves. The calculations performed, demonstrating its effectiveness, revealed examples of stable flows with over-compressed detonation wave in ducts of variable cross section.
Hierarchical database management model with uncertain parameters
Authors: Korotkova T I , Mokhov A A 
Published: September 2020

Abstract
Decision making in large technical, biological, economic and other systems always requires the creation of a complex information system. This implies the need to create sophisticated software for the safe storage of information, its updating and management. At the same time, there should be a convenient and easy to use interface that provides the user with all the necessary functions without unnecessary actions. In conditions of uncertainty, the volume of information becomes even greater. A central coordination system must exist to avoid data inconsistencies and redundancies and to increase the reliability of information storage in the database management system (DBMS). In this article, we propose using a database with a hierarchical structure. In such databases, it is possible to quickly update information at each level separately, without accumulating excessive amounts of information for the entire system.
Improvement of the Landau-Teller model for CO2 on the basis of the Chapman–Enskog method
Authors: Kustova E , Lukasheva A , Mekhonoshina M 
Published: September 2020

Abstract
Vibrational relaxation of carbon dioxide in the three-temperature kinetic-theory approach is studied. The focus is on the evaluation of the vibrational energy production terms in the coupled symmetric-bending and asymmetric modes. Using the generalized Chapman – Enskog method, the energy production terms are expressed as functions of the gas temperature, vibrational temperatures of CO2 modes and probabilities of corresponding transitions. It is shown that a modification of the Landau–Teller formula can be obtained from the rigorous theoretical expressions using several limiting assumptions. Whereas VT relaxation in the bending mode can be described by the Landau–Teller approximation with a satisfactory accuracy, its application to the inter-mode exchange requires introducing relaxation times depending on the vibrational temperatures of the modes involved to the transitions.
The influence of chemical reaction models on shock heated flow parameters in CO2/CO/O2/O/C mixture
Authors: Kosareva A , Nagnibeda E , Savelev A 
Published: September 2020

Abstract
In the present paper non-equilibrium flows of CO2/CO/O2/O/C mixture behind shock waves is studied taking into account vibrational excitation of CO2, CO, O2 molecules. The kinetic scheme includes vibrational energy transitions, dissociation, recombination and exchange chemical reactions. The problem is solved in the five-temperature kinetic theory approximation. The equations for vibrational temperatures of symmetric–bending and asymmetric CO2 modes and for diatomic species are coupled to the gas dynamic equations and applied to study flow parameters in the relaxation zone behind shock waves. Different models for one-temperature and multi-temperature rates of chemical reactions are used in calculations and the influence of exchange reactions and reaction models on flow parameters in the relaxation zone behind the shock wave is studied in the paper.
Effect of aspect ratio and end plates on rotational oscillations of thick plates in air flow
Authors: Shmigirilov R V , Ryabinin A N 
Published: September 2020

Abstract
The steady oscillations of elastically fixed thick plates in the air flow are considered. The oscillation amplitudes are measured using the strain gauge method. In experiments, the aspect ratio varies. Some of the experiments were performed with end plates. Steady-state oscillation amplitude increases with an increase in plate aspect ratio. In the presence of end plates, the oscillation amplitude linearly depends on the Strouhal number. Increasing the aspect ratio of the thick plate from 5 to 7 does not lead to a significant change in the amplitude of oscillations.
On the formation of a vortex couple in fluid
Authors: Gushchin V A , Smirnova I A 
Published: September 2020

Abstract
The task of forming a vortex couple in a homogeneous non-viscous fluid is investigated numerically. One of the latest variants of the Splitting Method for Incompressible Fluid (SMIF) developed by the authors is used to solve the problem. The finite difference scheme of the method has the following properties: the second order of approximation on spatial variables, minimal scheme viscosity and dispersion, monotony. It is shown that vortex couple is formed only at relatively short distances between the centers of vortexes. As this distance increases, the couple is formed longer in time. In the future, it is planned to take into account the impact of viscosity on this formation.
Issues of controlling the motion of a space object by the impact of the ion beam
Authors: Kulkov V M , Markin N N , Egorov Yu G 
Published: September 2020

Abstract
The problem of controlling the trajectory motion of space objects (SO) using particle beams interacting with the surface of the SO is considered. The source of high-energy particles can be an ion thruster mounted on board a spacecraft (SC). To evaluate the control forces, a model is presented that reflects the mechanism of interaction of the ion beam with the surface of the SO. The motion control for the center of mass of the “SC - SO” system is provided due to the thrust vectoring capability of the service spacecraft electric propulsion system (EPS). Mutual motion control of the SC and SO is ensured by controlling the position of the service spacecraft relative to the SO in the orbital coordinate system. In this paper, expressions for an asymptotically stable control process ensuring the transportation of SO with the specified characteristics are derived.
Study of the low-power krypton-operated stationary plasma thruster plume
Authors: Kim V P , Merkurev D V , Shilov E A , Zakharchenko V S , Kalyazin V G 
Published: September 2020

Abstract
The paper presents the results of experimental studies of the plume of low power stationary plasma thruster SPT-40 model, operating with krypton at discharge power of about 250 W, and with xenon at discharge power of about 200 W. A comparative analysis of the SPT -40 model plume characteristics was carried out that revealed significant differences in the distributions of current density of accelerated ions in the angle of deviation of the measurement directions from the thruster axis and in the distributions of average ion energies in the plume when operating with the above propellants. The flow parameters were measured by a multigrid probe – the retarding potential analyzer (RPA). This devise moved along the semicircular trajectory in a plane that included the thruster axis. The distance from the thruster exit plane to the RPA was equal to 6-7 outer diameters of the thruster-accelerating channel; at such distance, we can consider the thruster as a point source. The measurements were carried out at different operating modes in the propellant consumption and discharge voltage, and it is shown that during the SPT-40 model operation with xenon and krypton the half-angle of the plume divergence was about 70 degrees in the discharge voltage range 150-200 V and it decreased with the discharge voltage growth.
Biharmonic spline interpolation of spatial dose rate distribution in the minimum dose trajectory optimization problem
Authors: Starchenko A E 
Published: September 2020

Abstract
In this paper issues relating to geostationary orbit (GEO) insertion trajectory optimization is considered. The article discusses the GEO transfer trajectory optimization for a spacecraft with an electric propulsion (EP) system with the purpose of reduction of ionizing radiation dose absorbed by onboard systems from the Earth’s radiation belts. The considering trajectory optimization technique is based on the Pontryagin’s maximum principle and the method of numerical continuation. Much attention is paid to smooth approximation of the dose rate dependence on spatial coordinates using biharmonic splines interpolation. The proposed method makes it possible to abandon the methodological simplification of averaging the radiation dose rate over circular orbits to effectively solve this class of problems and directly consider the dependence of the dose rate on time and geographical longitude. Using as an example the minimum time problem for a test transfer, the errors in calculating the dose at the end of the transfer both by the proposed method and by the method of averaging over circular orbits are estimated. The proposed method turned out to be more than 13 times more accurate than the analogue. It can be applied in transfer trajectory optimization problems of an EP spacecraft in order to minimize the total accumulated ionizing radiation dose.
The use of CFD calculations for the solution of the control problem of applying protective coatings of varying thickness
Authors: Borisov S A , Glukhovskaya Ju I , Dobrovolskiy S V , Podporin I V 
Published: September 2020

Abstract
The paper analyzes the results of simulation of a supersonic air flow about simple 3D forms in order to use them for applying protective coatings to the surface with varying thickness by means of cold gas-dynamic spaying. To calculate the results, an aerodynamic analysis is performed in SolidWorks Flow Simulation software environment. Air flow zones on a streamlined surface with various characteristics (pressure, temperature, geometric shape, etc.) are analyzed, and possible methods of determination the boundaries of these zones are considered. For the solution of the control problem of applying protective coatings of varying thickness, the displacement behaviour of the movable nozzle with a small cross section is considered.
On solving the warehouse procession optimization problem using a tuple of heuristics
Authors: Gainanov D N , Korablev I G , Rasskazova V A 
Published: September 2020

Abstract
The paper is a review of the present-day problem about the logistic optimization of both two-dimensional and three-dimensional warehouses with m cranes. A tuple of heuristic algorithms is proposed to solve the NP-hard problem with minimizing the total execution time of a set of jobs using m cranes. The described optimization approaches are applicable to both two- and three-dimensional warehouses. As part of the numerical results, results regarding the solution of applied problems are shown. The ability to train the proposed model allows one to select the best heuristic settings for a specific warehouse based on real world data sets. Another important feature of the model is the ability to distribute the power and parallel execution of three independent processes: the ant colony optimization algorithm to construct a successful sequence of jobs, the algorithm to search the optimal set of heuristic weights of ki
, and the algorithm to solve the planning problem.