## Vol 15, No 2 (2016)

**Year:**2016**Articles:**22**URL:**https://journals.ssau.ru/vestnik/issue/view/148

### Full Issue

###### Abstract

The problem of forming command control of the subhypersonic first stage of an aerospace system in climb is considered. Passive motion of spacecraft in conditions of maximum atmospheric density disturbance is analyzed. Achieving the prescribed value of the angle of climb is the terminal motion condition. Terminal height is a controlled value. An algorithm of terminal control for the formation of command value of aerodynamic lift coefficient is proposed. The Newton method with one or more iterations at the correction step is used in determining command control. The serviceability and efficiency of the algorithm compensating the influence of variations of atmospheric density on the preset terminal altitude condition of spacecraft motion are analyzed. The results of simulating spacecraft motion with terminal control for maximally «rarefied» and maximally «dense» atmosphere are discussed. Possible improvement of the terminal control algorithm is suggested.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):9-21

###### Abstract

A complex of wide-swath multispectral equipment CWSME installed on the “Resource-P” spacecraft is discussed in the paper. The complex contains a high resolution camera, a medium resolution camera and a control unit. Each of the two cameras has 6 spectral channels – one panchromatic and five multispectral ones in the visible light and near infrared band. The use of a speed lens and a single linear CCD light sensor with a great line length is the distinguishing feature of the complex. The use of a single light sensor makes possible seamless background and ensures high accuracy. The CWSME can be used for a wide range of purposes: creation and revision of topographic maps; monitoring of agricultural and forest lands; identifying bodies of forest wildfire; monitoring flood hazard areas etc. Examples of CWSME shots and prospects of equipment modernization are presented in the paper.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):22-29

###### Abstract

The article describes the equipment for the future spacecraft «Resource-PM». The main technical characteristics of the equipment are presented. The equipment includes an optical system, panchromatic and multispectral optoelectronic converters, a memory unit, a control unit and star sensors. The design specification for the equipment included unprecedented requirements for the resolution, efficiency, sensitivity and accuracy of coordinate referencing. In order to meet the requirements a new large-sized optical system, three types of large-format photo sensors, multichannel interference light filters, a high-speed large-format matrix for the star tracker, new algorithms of digital processing and compression of information, high-speed interfaces of data transmission with fiber-optic components had to be developed The structure of the optical system incorporates a carbon fiber dimension-stable structure, which, combined with lighter mirrors ensured light weight of the objective and high image quality. The equipment makes it possible to survey the Earth surface in panchromatic and eight narrow spectral channels with high spatial resolution.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):30-35

###### Abstract

The article deals with problems associated with determining permissible accuracy of Earth remote sensing satellite control over observation intervals taking into account the interaction of optronics and charge-coupled devices with time-delay and integration (CCD TDI). The control accuracy requirements are determined for the condition that the allowable image shift value should not be exceeded. The allowable accuracy is proportional to the time of exposure of a resolution cell which depends on the number of CCD array storage rows and image motion velocity. The discrepancy between the image motion velocity supported by the optronics and the Earth surface scanning velocity depends to a large extent on the satellite control accuracy regarding its angular position and rotation about the centre of mass. Angular motion over observation intervals is formed based on the condition of constant specified longitudinal velocity and zero transverse velocity of image motion relative to the frame centre. The dependence of the frame-centre image shift value on the spacecraft angular motion control system follow-up errors is determined. Based on the obtained relation, an algorithm of determining allowable angular motion follow-up errors is proposed. The angular motion follow-up error influences the accuracy of the optronics optic axis pointing at the central route line. The article gives examples illustrating application of the proposed algorithm as well as assessment of en-route targeting accuracy.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):36-42

###### Abstract

The study presents the principles of application of simulation modeling in conducting static tests of aerospace products using the small satellite (SS) «Aist-2D» as an example. Limitations of static tests that do not allow comprehensive analysis of the stress-strain state of a satellite are discussed. For example, it is not always possible to install sensors for measuring stress in remote locations. Simulation static tests using the finite element method with the use of the finite- element analysis MSC. Patran/Nastran package is proposed as an additional method of analyzing the stress-strain state of a product. The goals and tasks of the simulation tests are formulated and the main stages of the simulation modeling tests are described. To obtain consistent results of simulation modeling tests validation of the finite- element model of a satellite is required. The validation consists in confirming the adequacy of the model by analyzing the stress-strain state of the structure of the satellite. The main advantage of the simulation modeling test is the reduction of the cost of preparing and conducting the static tests. The efficiency of the method was confirmed in conducting the simulation modeling tests of the SS «Aist-2D», held in parallel with the static tests of the satellite. Thus, the application of the method of simulation modeling of static tests makes it possible to reduce the costs of static tests, improve the quality of static strength experiments and, consequently, increase the reliability of the satellite.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):43-49

###### Abstract

Algorithms for determining the attitude and angular rate damping of the SamSat-218D nanosatellite developed at Samara State Aerospace University are described in the paper. The date of the prospective launching of the satellite into the Earth orbit from Vostochniy spaceport is April, 2016. A triaxial magnetometer and luminance sensors are used as sources of information in the orientation system. Three magnetic coils serve as actuators providing the angular rate damping onboard the nanosatellite. A known method of vector coordination with the original criterion of preliminary measurement rejection is used as the orientation determination algorithm since the vector coordination method is very sensitive to measurement errors. The traditional B-dot algorithm is used as the damping algorithm. The influence of the initial angular rates on the magnetic moment coefficient in the B-dot control algorithm is studied. Since the continuous mode of operation of magnetic coils on board the nanosatellite is unpractical due to the necessity of measuring variations in the Earth magnetic field intensity vector the damping process is analyzed in the discrete mode of operation at different values of angular rates of nanosatelite separation. The comparison of the algorithm processing speed in the continuous and discrete operating modes at various initial angular rates of separation is given.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):50-56

###### Abstract

Obtaining a new optimal law of controlling onboard magnetic coils that would provide reduction of the angular momentum of nanosatellites and microsatellites to a predetermined small value and subsequently maintaining it is discussed in the paper. The study shows that the use of a new time-optimal control law contributes to a significant increase in the high speed performance of the magnetic attitude control system in the tasks of reducing angular momentum of satellites to small values. The problem of satellite angular rate damping in accordance with a reference model – a system of three independent linear homogeneous equations – is discussed as well. Some numerical results of the application of these laws to the problem of reduction of satellite angular momentum and angular velocity are presented. Advantages and drawbacks of the new time-optimal laws of control of angular momentum of nanosatellites and microsatellites are specified.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):57-67

###### Abstract

The paper deals with the methodological approach to the development of a problem-oriented system of automated design. The system enables interactive setting and solving of design problems, updating design parameters and obtaining the results required for Earth remote sensing satellites quickly and efficiently. The process of setting and solving problems with the help of the system under discussion involves the following stages: input of the design object parameters and connection operators; setting of input (known) and output (required) parameters; checking of the problem accuracy and solvability; determining, for each variable, the equation it may be found from; dividing the mathematical model into separate models; determining the sequence of steps in solving the problem; calculating the numerical values of required parameters. The development of a problem-oriented system can be carried out using methods of the theory of sets and theory of graphs that makes it possible to automate the process of solving design problems. The methodology under consideration is implemented in software developed in Java programming language that allows solving problems of high dimensionality. Illustrative examples are given.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):68-79

###### Abstract

New optoelectronic telescopic complexes to be implemented are currently selected on the basis of painstaking and long-term research in which scientific research institutes of the customer and space-rocket branch, as well as enterprises specializing in producing optoelectronic telescopic complexes and space vehicles of Earth remote sensing take part. A technique of ranking optoelectronic telescopic systems according to the degree of influence on the target characteristics of a space observation system (linear ground resolution, frequency of observation, accuracy of georeferencing, efficiency of delivery of remote sensing information etc.), taking into account possible changes in the design parameters of remote sensing spacecraft and the cost of new projects is proposed. The technique is based on the use of software for preliminary estimates of mass-dimensional and other design parameters of ERS satellites depending on the preset performance targets of space systems. The method proposed makes it possible to carry out prompt analysis of the efficiency of implementing some technology connected with choosing the design characteristics of Earth remote sensing space satellites equipped with optoelectronic telescopic systems.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):80-89

###### Abstract

The paper is devoted to the study of thermal control of the platform of star sensors designed for spacecraft attitude control under operating conditions. An optimal platform design with an arrangement of sensing elements is presented. The temperature field and the stress-strain state of the platform under the influence of heat sources is considered taking into account the operation of an air-conditioning system based on a numerical solution of a coupled thermoelasticity problem. The temperature field and the strain fields are calculated using the finite-element method with the help of the ANSYS software package. A finite-element model of the platform is developed on the basis of a geometric 3D model. The steady-state velocity field of the coolant in the platform channels is calculated at first. Then the temperature field of the platform is calculated with account for the coolant dynamics. The strained state of the platform under the influence of heat is calculated on the basis of the calculated temperature field. Angular deviations of the mounting seats of star sensors (2 degrees on the average) are determined as compared with the undeformed state. It is shown that angular deviations of the seats of star sensors do not exceed admissible limit values (5 arc seconds). Proposals for creating a high-precision star sensor position control system with a 1 arc second-accuracy are developed.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):90-101

###### Abstract

The stability of motion of a space tether system with an atmospheric probe is investigated in the paper. The equilibrium position stability of a space tether system near the local vertical (static stability) and deployment stability (dynamic stability) is studied. A tether system consists of spacecraft from which the tether is deployed and an atmospheric probe. The Lagrangian method is used to derive a dynamic model of the tether system’s motion in a mobile orbital system of coordinates considering aerodynamic forces acting on the spacecraft and the probe. The conditions of tether system motion stability with respect to the local vertical are determined. Analytical analysis is confirmed by numerical examples.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):102-113

###### Abstract

The paper presents the results of an experiment on the formation of thin films of barium disilicide (BaSi_{2}) – a promising material for solar cells using the method of solid-phase epitaxy. BaSi_{2} was formed in ultrahigh vacuum on silicon substrates with the use of template technology. At the final stage of the formation of nanostructures the films were recrystallized by annealing. The resulting thin films were investigated by in-situ methods: Auger electron spectroscopy and electron energy loss spectroscopy. Then ex-situ techniques were used: atomic force microscopy and X-ray diffraction. The latter method showed the presence of a-oriented barium disilicide in the film formed at the temperature of recrystallization T = 800 ^{0 }C. The spectra of Auger electrons and electron energy loss for the film are presented. The analysis of surface topology nanostructure obtained by atomic force microscopy shows that its surface roughness is comparable with the roughness of thin BaSi_{2 }film samples formed by molecular beam epitaxy. The reason for a small amount of crystallites BaSi_{2} formed, as we see it, is low interdiffusion of barium and silicon atoms in the case of using the chosen method of forming a film. The use of the Ba and Si co-deposition technique, followed by recrystallization of the film at temperatures close to the temperature specified in the paper appears to be the solution of this problem.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):114-121

###### Abstract

Two coherent radiation sources with the wavelength of 532 nm and 632.8 nm are used in a speckle interferometer optical arrangement with combined beams and speckle-modulated background wave. The reference beam is formed with the help of a diffuser located in front of the object under investigation. The use of two radiation sources in the optical arrangement makes it possible to increase the number of experimental points, which is necessary for improving the accuracy of measuring static displacements of the surface of the part under investigation. A diagram of normal displacements of the leading edge of a blade of the 7^{th} compressor stage under bending deformations has been plotted using additional experimental points. A digital still camera is used as a registering device. Two speckle-interferograms have been obtained at different wavelengths of a blade of the 9-th compressor stage under torsion with the use of the long-wavelength speckle interferometer. It was proposed to use a pattern that represents the product of these two speckle-interferograms in order to determine the zero band. A method of determining the zero band under torsion has been developed for the case when the part of the blade surface adjoining the attaching point is not available for observation and several shadow bands fall on the attaching point at once. This methodology has been tested for zero band determination on a speckle-interferogram obtained under static torsion of a blade of the 9-th compressor stage.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):122-130

###### Abstract

The study covers the development of a mathematical model of a micro gas turbine (MGTE) operating under transient conditions using a recurrent neural network. The compressor inlet temperature and pressure depending on the aircraft height and speed are taken into account explicitly. A full-size mathematical dynamic MGTE model based on engine per-unit description was used to verify the developed model. The obtained model was compared with the existing one employing normalized parameters of aircraft flight level and airspeed. The simulation suggests that the proposed model yields significantly smaller errors than the existing one, whereas the computation time of both models differs insignificantly.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):131-144

###### Abstract

The paper presents the results of work on reducing vibration of valves under transient conditions. The main parameters that influence the vibroacoustic characteristics of tube fitting in opening and closing of valves are distinguished: actuator types, geometry of the flow area, operating conditions. The process of formation of the dynamic force acting on the closure element of the fitting is examined. Time-dependent characteristics of flow resistance coefficients, flow velocity and dynamic force are given. The possibility of choosing the operating conditions providing minimum vibration of the valves is determined. A new design of the ball valve closure member is proposed. The analysis of the flow area is carried out using methods of numerical simulation. The flow pattern, the presence of reverse-flow areas, formation of eddy flows are shown, the pressure drop and flow resistance coefficient are specified. The results of experimental research of vibration are presented. The level of vibration of valves is shown to decrease under transient conditions, which results in ensuring safe operation of valves, reducing sound emission and improving working conditions of the operating staff. The results of research can be used to develop new designs of valves.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):145-151

###### Abstract

The article suggests an empirical method of predicting noise of aircraft gasoline engines with carburetion used in light and unmanned aviation. The method is based on classical approaches of aeroacoustics to the calculation of environmental noise from different sources. The spectrum of acoustic power is proposed to be obtained on the basis of an empirical model similar to the known M. Khekl҆ model for the calculation of noise of internal combustion piston engines of ground application, but at the same time taking into account the key features of aircraft engines. The calculated and experimental data on integral characteristics of the acoustic field of aviation piston engines are shown to be in good agreement. Experimental data on the noise of aviation piston engines like Ash-62IR, M-14P, ROTAX-912ULS with and without cowling, ROTAX-582UL were obtained during acoustic tests of light propeller aircraft An-2, Yak-18T, MAI-223M, MAI- 890U and MAI-890, respectively, under static conditions at a local aerodrome. At the same time the acoustic field of the piston engine was supposed to be axially symmetrical relative to the crankshaft axis and the noise of the engine was determined by the total radiation at the harmonics of flash recurrence rate in the cylinders.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):152-161

###### Abstract

Compressor blades are among the numerous and complicated parts of gas turbine engines. A freeform surface of compressor blades is characterized by a complex of parameters distinguishing the geometry of their individual sections. The paper presents a model of calculating a complex of geometric parameters of blade profiles by a measured array of points. A method of estimating the uncertainty of measurement of a set of geometrical parameters with the use of coordinate measuring machines is developed. Software algorithms have been designed for the implementation of the proposed models and methods. The paper presents the results of analyzing errors of measurement of a set of geometrical parameters of the gas turbine engine compressor blade airfoil. We obtained the probabilistic characteristics of arising errors for three cross sections of the blade airfoil. The proposed models and algorithms for computing a complex of geometric parameters of the measured profiles by an array of points can be applied to software for measuring machines.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):162-170

###### Abstract

A procedure of assessing the main characteristics of angular velocity inertial meters of middle and low accuracy classes, including measuring channel noise terms is proposed. The procedure is based on the processing of the meter output information by means of the Kalman discrete filter and the Allan variance method. The characteristics to be estimated are: scale coefficient errors and zero signal shifts, as well as series of standard noise terms. Estimates of the method error level for the procedure under consideration are given on the basis of mathematical simulation of the measurement information and its correction with different estimated errors. An example of approbation of the technique is processing the results of tests conducted for two inertial meters based on different operating principles. One of them is the ADIS16405 device developed by Analog Devices (USA) on the basis of three micromechanical gyroscopes of low- accuracy class and the other is the ВГ910-МК470 device designed by Fizoptika, CJSC (Arzamas city) which consists of one fiber-optic gyroscope of the middle -accuracy class.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):171-182

###### Abstract

A method of lossless digital image compression is presented in the paper. Its implementation demands minimum computing resources and it can be efficiently used in Earth remote sensing systems. The method makes possible maximum removal of statistical redundancy of images without spectral transformations. A digital image is resolved into bit planes which are processed independently of one another. That allows their parallel processing without any restriction on the pixel length of the image. Each bit plane is approximated by a two-dimensional Markov random field with discrete values. Prediction of elements of the bit plane is accomplished on the basis of the theory of conventional Markov processes. Only operations of logical comparison are used for the prediction, whereas computational operations such as multiplication and addition are not required, which makes it possible to increase the speed of image processing. The research conducted shows that the method is not inferior to known methods of lossless compression in its efficiency, while being considerably superior to them in the speed of processing. The method is applicable both to panchromatic and color images and can be used in any systems of digital image processing.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):183-189

###### Abstract

The paper introduces a method of prompt orthotransformation of space images, based on the integration of the orbital and polynomial methods of photogrammetric image processing. The concept of the method consists in fragmentary formation of an orthoimage. Fragments (quadrangles) of a definite size are marked in space images, so that geometric constraints between their elements are adequately described by a bidimensional polynom of the first order. The adjacent fragments have common vertexes on the contact line, providing integrity of the orthoimage being formed. The location of the fragment (the coordinates of its vertexes) is defined by the orbital method with consideration for the configuration of terrain, thus, if the fragment is small enough, it provides terrain correction for all the points of the fragment. To use the orbital method we define initial values of the orientation angles of the on-board equipment of the spaceship and the laws of variations of these angles in course of survey with subsequent specification of these values in terms of the coordinates of four check points. The compliance between tolerance points of fragments of the initial image and the image being formed is achieved on the basis of the models, the implementation of which is computationally less complex than that based on orbital methods. Experimental approbation of the proposed method proved that the method of prompt orthotransformation makes possible four-fold reduction of the time of photogrammetric space image processing while providing comparable accuracies of the resulting images.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):190-199

###### Abstract

An approach to solving problems of identifying Earth surface objects on the basis of hyperspectral survey data obtained from space complexes based on the comparison of hyperspectral characteristics of the objects investigated with a set of reference signatures is presented in the paper. Algorithms of object identification with the use of the theory of fuzzy sets are proposed: an identification algorithm based on fuzzy linear regression and an algorithm of consolidation of results of different identification solutions. The fuzzy linear regression algorithm is based on the use of non-symmetrical triangular fuzzy numbers. This approach, used earlier in solving approximation tasks and assessing the unique character of electronic map fragments is now used for the first time for the identification of hyperspectral characteristics. The choice is founded on the fact that fuzzy linear regression makes identification possible in ambiguous conditions. The results of experimental studies of the proposed algorithms based on real hyperpsectral survey data (from spacecraft «Resurs-P» N1) are presented in the form of 10 images. Identification reliability is shown to increase by 6.1 % as compared with one of the initial algorithms yielding the best solution in the case of consolidating results obtained by using algorithms based on the Euclidean distance similarity measure, the angle similarity measure, as well as fuzzy similarity measures.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):200-207

###### Abstract

The paper presents an analysis of approaches to using apriori information on relief to improve the quality of spaceborne SAR data interferometric processing. The impact of relief on geometric matching of SAR images is analyzed and an algorithm of fast and high-precision SAR image matching based on polynomial approximation of relief height impact is proposed. The necessity of perpendicular baseline refinement, given the current accuracy of navigation data, is shown. The need of using reference relief to refine the baseline is also shown. The expediency of baseline refinement before and after phase unwrapping is substantiated. The impact of the steepness of relief slope on the coherence estimation is calculated. The existing methods of phase unwrapping are analyzed and an algorithm of their combining is proposed, based on apriori information on each method. A criterion for selecting areas on the interferogram where the true phase varies greatly from pixel to pixel because of the steep relief slope is presented. Phase – to - height conversion is also considered. Using publicly available global low resolution DEMs as apriori information on the relief is proposed.

**VESTNIK of Samara University. Aerospace and Mechanical Engineering**. 2016;15(2):208-219