Vol 19, No 2 (2018)

In connection with the emergence of abnormal situations at the stage of launching space vehicles (SV) for various purposes (AngoSat-1, Telkom-3, Phobos-Grunt, etc.), the problems of timely detection of such situations and remote monitoring of the technical condition of SV are of vital importance. To assess the feasibility of solving this class of problems with the use of optronic equipment (OE), it is necessary to have a priori information on the spectroenergetic characteristics (SEC) of a SV and associated backgrounds for the projected angles and conditions of observation in the operational spectral ranges of the OE taking into account the illumination by the Sun and the Earth. Due to the adapta- bility of mathematical modeling to the high degree of variability of the above factors, this method can be considered as a rational one for obtaining dynamic SEC (signatures) of SV for observation conditions that change during an or- bital flight. The technology of SEC modeling of space objects (SO) with the use of FemRad dedicated software (DS) is pre- sented, which provides the production of SO SEC taking into account the indicatrices of the scattering of optical radia- tion from materials and coatings of the external surface of the object, the dynamics of its thermal regime and the condi- tions of illumination by the Sun and Earth during the orbital flight. The advantage of the presented technology is the compatibility of the developer’s own software solutions with the widespread application programs of finite element analysis. In particular, the known CAD and CAE tools - SolidWorks, ANSYS, Gmsh - are used to develop grid geometric 3D models of SO. The method for parametric approximation of the measured indicatrices of scattering of optical radiation from mate- rials and coatings of SO on the basis of a given model of roughness is considered. The main provisions of the DS meth- odology for calculating the heat flux of the “Earth-atmosphere” system, as well as the fluxes of reflected and scattered solar radiation falling on the SO in the range 0.2-20 µm, are presented. The results of modeling the dynamic SEC of a typical SO in the infrared (IR) range are given as an illustration of the application of the DS.

For the first time the definition of the Cayley graph was given by the famous English mathematician Arthur Cayley in the XIX century to represent algebraic group defined by a fixed set of generating elements. Now the Cayley graphs are widely used both in mathematics and in applications. In particular, these graphs are used to represent computer networks, including the modeling of topologies of multiprocessor computer systems (MCS) - supercomputers. This is due to the fact that Cayley graphs possess many attractive properties such as regularity, vertex transitive, small diame- ter and degree at a sufficiently large number of vertices in the graph. For example, such a basic network topology as the ”ring”, ”hypercube” and ”torus” are the Cayley graphs. One of the widely used topologies of MCS is a k- dimensional hypercube. This graph is given by a k-generated Burnside group of exponent 2. This group has a simple structure and is equal to the direct product of k copies of the cyclic group of order 2. Now the Cayley graphs of groups of exponent 3, 4, and 5 have already been studied. In this paper we research the Cayley graphs of some finite two- generated Burnside groups of exponent 7. The computation of the diameter of the Cayley graph of a large finite group is a solvable but very difficult problem. In the general case the problem of determining the minimal word in a group is NP-hard ( nondeterministic polynomial ) . Thus, in the worst case, the number of elementary operations that must be per- formed to solve this problem is an exponential function of the number of generating elements. Therefore, to effectively solve problems on Cayley graphs having a large number of vertices, it is necessary to use MCS.

The process of propagation of plastic deformations in a semi-infinite elastic plastic rod caused by dynamic loading applied to the end of the rod, which is not decreasing in time, is considered. The equations are written in the Lagrangian coordinate system. It is assumed that during deformation there is no lateral bulging of the rod and that the influence of transverse deformations of the rod on the process of propagation of longitudinal waves is negligible. At the initial moment, the rod is in a deformed and dormant state. Small deformations of the rod are considered. The density of the rod during deformation does not change. The only non-zero component of the stress tensor will be the component along the ox axis, non-zero components of the strain tensor will be the components along the Ox, Oy axes. As a result, a system of two quasilinear first-order homogeneous equations is constructed. The equations are hyperbolic. They are built for performance and ratio on them. Next, the equations are written in terms of Riemann invariants. For the equations constructed, the conservation laws are found in the case when the current remaining depends only on the functions sought. As a result, a system of linear equations with coefficients depending only on the required functions is obtained. Тhe construction of conservation laws is reduced to the solution of the boundary value problem for the known Euler-Poisson-Darboux equations. This problem is solved with the help of Riemann functions. The conservation laws allowed us to find the coordinates of the points of intersection of characteristics, and thus to solve the problem. In conclusion, the article considers the case when one of the characteristics crosses the line on which the initial conditions are given. In this case, as is known, the Cauchy problem cannot be solved. This leads to a procedure which, with the help of conservation laws, makes it possible to find out the solvability of the Cauchy problem. It is reduced to the solution of a simple integral equation by the method of successive approximations.

Satellite systems are one of the most common methods of tracking various objects around the world. There are vari- ous types of satellite systems for different purposes, but their common feature is data transmission by radio signal. The atmosphere of our planet is nonuniform and its every layer has some characteristics which impede data transmission. In case of insufficient power supply the transmission is practically impossible. That is why there should be worked out special methods and algorithms able to mitigate the atmospheric effect on the signals of the aircraft monitoring devices. The ionosphere, in particular, is the main cause of errors in determining the object’s location. For “Iridium” satellites that receive signals from “Iridium 9602” module at frequency of 1616-1625.5 MHz the ionosphere influence induces the alteration of the signal power due to the inhomogeneity of charged particles. The article presents the calculation of attitude data transmission loss in space as they are transmitted by “Iridium 9602” transceiver up to heights of 450, 500 and 600 km. The proposed method is based on modeling the current map of the total electronic content of the ionosphere. On the basis of this model, a correction of determining the monitored object’s location can be made. Today there are several centers performing calculation of total electronic content of the ionosphere. The calculation results are in free access. Thus, having the initial data obtained from the maps of the total electronic content of the ionosphere and the algorithm for making corrections, it is possible to correct the data while solving navigation problems. In particular, the GEMTEC model can be used, as its source of data is a map of total electronic content of the atmosphere.

The final stage of designing a cable network of spacecraft (as well as any other product) is the release of design and operational documentation. The automation of this process allows to improve the quality of documentation and de- crease the manufacturing time of spacecraft. The JSC ”Information Satellite Systems” (ISS) uses its own integrated software complex ”ALCAB” for releasing design documentation package for a cable network. For the assembly drawing development, the company uses CAD without integration with ”ALCAB”. In this regard, adding or removing items in the specification leads to the further refinement of the drawing. We propose the technique of solving a problem connected to the automation of the assembly drawing development for a cable network produced on a plane. The main task is to create associative link between the specification items and the cable network drawing. In this article we present the results of the analysis of the structure of the cable network 3D model designed in ”CATIA V5” CAD. There are schematic examples of harness topologies. The analysis identified the list of data to be extracted from the 3D model. We described the most interesting tools of ”CATIA V5” CAD that allow you to automate many processes including the development of your own software solutions. The analysis identified the tools for automated uploading of all re- quired data from the model. The examples of these tools are ”Knowledge Expert” and external programming environ- ment ”CAA RADE”. The analysis of their performance showed that the extraction of data using an algorithm developed with ”CAA RADE” was faster than using ”Knowledge Expert”. We described the potential of drawing tools in ”CATIA V5” CAD such as ”Electrical Harness Flattening” and ”Drafting” that allow you to automate the assembly drawing development. The paper proposes the method of automating he assembly drawing development of a cable network developed with the use of three-dimensional technology using the tools of ”CATIA V5” CAD and software designed at the JSC ”ISS”.

A solar simulator is one of the most difficult elements of the test equipment used during ground testing of space- crafts. The majority of modern large-size simulators are designed on the basis of the block of gas-discharge xenon lamps with air cooling using the principle of the "combined focuses". The main shortcomings of similar simulators are a low efficiency and a small resource of xenon gas-discharge lamps, high losses in the difficult optical system, complex- ity, and inconvenience of operation. The scheme of the combined simulator free from the specified shortcomings based on the high-effective light-emitting diodes in visible area of a range and additional traditional sources which can be quartz-halogen filament lamps in infrared and gas-discharge medium-pressure mercury-vapour arc lamps ultra-violet areas is offered. The LED source is structurally executed in the form of matrixes with the distributed parameters, lo- cated in the form of one or several modules in the thermal vacuum camera directly near the object of testing. Modules are supplied with the optical system forming a quasiparallel light stream, the heat insulation and the cooling system removing excess heat out of camera borders. The short comparative analysis showed advantages of the LED simulator on energy efficiency, uniformity and temporary stability of a light stream, reliability, durability and safety. The offered simulator possesses the best mass-dimensional characteristics, doesn't demand tuning and adjustment and has a num- ber of additional opportunities. The main disadvantage of LED sources is the discrepancy of the solar radiation spec- trum. Essential spectral accuracy can be reached at application in matrixes of a large number of separately power- controlled groups of white and monochrome light-emitting diodes with different length of waves and the optical system summarizing flows of groups of light-emitting diodes on a range, a corner and the area. On examples of serially pro- duced foreign LED solar simulators of a ground-level AM1,5 range the tendency of transition to LED sources is traced. It is concluded that the creation of the combined solar simulator on the basis of highly effective light-emitting diodes for ground testing of spacecrafts possessing the improved technical and operational characteristics is possible.

Modern requirements to increase spacecraft active existence lead to the efficiency of all its resources use improve- ment. And one of the main spacecraft resources, which determines the period of active existence, is the orientation en- gines fuel. The fuel consumption of the orientation engines depends on the external disturbance torques affecting the spacecraft. The work is devoted to the development of a mathematical model that allows to determine external distur- bance torques continuously affecting the spacecraft. The mathematical model is based on the assumption that the ki- netic moment of the spacecraft remains unchanged in the inertial coordinate system. The use of an active flywheel ori- entation system makes it possible to measure a spacecraft kinetic and disturbance moments. A special feature of this measurement is the rigid connection of flywheels with the spacecraft body that rotates at an orbital speed. This feature makes it necessary to take into account the kinematic relationship of the flywheel kinetic moment with the kinetic and disturbance moments in the inertial space. Thus, according to the kinetic moment variation law, it was possible to ob- tain a mathematical model for the interrelation between the flywheel kinetic moment and external disturbance torques. To test the model, two of the most common methods of mean-square filter readings were examined: the Gaussian filter and the Kalman filter. Modeling systems of equations and coefficients of error matrices were determined for modeling. The model was tested in the GNU Octave mathematical computing environment using telemetry information received in 2017, from medium-sized spacecraft (based on the Express-1000H platform) and heavy (Express-2000) class. To com- pare the results, the graphs for calculating the kinetic moment from the model and the measured kinetic moment from the flywheels are given. The mean-square deviation of the compared values did not exceed 0.1 Nm for the Gaussian filter and 0.03 Nms for the Kalman filter. The graphs of disturbing torques estimation by a mathematical model are given. The mean-square deviation of the estimate of the disturbing torquess for the Gaussian filter did not exceed 0.9 % and for the Kalman filter it was 2 %. The convergence of the disturbing torques estimates shows the adequacy of the developed mathematical model.

The article gives the short information about the history of the development of photoelectric generators (silicon and based on AIIIBV compounds) and solar arrays based on them for spacecrafts. The main factors of outer space are listed and the evolution of structure is demonstrated. The principal structure of modern triple junction InGaP / InGaAs / Ge solar cells with indication of the functional purpose of the layers is given and their main characteristics are presented. The mechanism of degradation of electrical parameters of such solar cells under the action of cosmic radiation is explained and the possibility of minimizing this negative effect is described. The main methods and technological peculiarities of triple junction solar cells production are discussed. The review of solar cell for space application based on AIIIBV compounds produced by the world's leading manufacturers from the USA, Germany, Italy and the Russian Federation with its external appearance and the description of the features of the constructions and main properties are presented. It is shown that the most common is the solar cells size with an area of ~ 30 cm2. Information on established triple junction InGaP / InGaAs / Ge solar cells large area is presented (up to ~ 60-65 cm2). The world level of effi- ciency of solar energy conversion is achieved in industrial production, amounting to 26-30 %. The information about solar cells for conversion of concentrated solar radiation is provided. The basic directions for improving the character- istics of solar cells based on compounds АIIIBV are shown.

The article considers the types of a compact gyroscopic angular rate measurement, which were designed and developed in Kuznetsov Research Institute for Applied Mechanics. The devices are based on the dynamically adjusted gyroscope with a rotor gas-lubricated spin-axis bearing system. Two types of the compact gyroscopic angular rate measurement are intended to Russian space crafts. Third of them are intended to the foreign space crafts. Three gyros are sensing elements for the compact gyroscopic angular rate measurement. Disposition of gyro into gyroscopic is the main difference of these types of the compact gyroscopic angular rate measurement. The main goal of this article is to make a research of mechanical influences on the compact gyroscopic angular rate measurement and to create the protecting systems of gyro from the mechanical influence on a new gyroscopic device. The article considers the main technical characteristics of gyroscopic device: dimensions, weight, accuracy of measurements, and number of measuring axes, resource of work device, energy consumption and so on. The paper describes advantages and disadvantages of the dynamically adjusted gyroscope with a rotor gas- lubricated spin-axis bearing system. There are the following advantages: dimensions, weight, accuracy of measure- ments, and number of measuring axes, resource of work device. The disadvantage is a necessity to protect systems from the mechanical influence on launching rockets. The article considers the main principles of protecting systems. It’s about a theoretical model system of protection of the gyroscopic device from mechanical resistance and theoretical information. Due to a theoretical model it’s possible to choose constructional characteristics of the protecting system from mechanicals influences during a design stage. It’s about dimensions spring and damper. Criterion for the choice is acceptable for the dynamical characteristics of gyro. The article has also saved the results of the mechanical test of the gyroscopic device.

The manufacture of parts and assembly units of the aerospace industry is characterized by a small product range, but a significant changeability of their shape and size. In these circumstances, the use of the elements of universal as- sembly devices (UAD) allows to reduce the number of special devices significantly. Based on the results of a complex research on the analysis of design and manufacturing technology of elements of UAD, and on the known principles of construction of group technologies the algorithm for the formation of technological groups of UAD details of the ”prism support” type was developed. The 3D-model of the complex details, the classification of surfaces proposed for it and the database on all 16 details of the group are the basis for the development of an algorithm for a route group technological process (GTP). In the new GTP and control program it is proposed to combine in one operation practi- cally all draft types of processing: milling, drilling, thread cutting on the multi-task machine with the palletization of complex details on a technological plate. The effectiveness of the constructive-technological decisions is confirmed by the reduction in the number of operations and equipment (from 7 to 4 machines) thus reducing the labor content and cost. The use of the developed techniques of development the GTP allows significant expansion of the possibilities for automation of technological preparation of production, simplifies the development of control programs, reduces the labor content of the preparation of technological documents and its translation into digital form.