2015. № 83
Mechanics | |||||||
Fluid, gas and plasma mechanics | |||||||
The basic idea of this scientific work was the study of the evolution of the velocity profiles over the underlying surface. The purpose of the work was to obtain the vision of change in the velocities distribution in the flow over the surface with the adhesion condition in relation to a given initial velocity profile. The initial profile of the wind around the boundary layer. It also presents physical and mathematical explanation of the derivation of the velocity profile of wind on the basis a two-layer model of the boundary layer. The conclusion was based on the theory of M.I. Yudin and M.E. Shvets for the coefficient of turbulence. Moreover, in this work we simulate the wind profile evolution for flowing over flat surface with the length of 10 km, obtained on the basis of two-layer model. The modelling was carried out by the numerical integration of the Reynolds equations with the closure of turbulence model SST. It was verified by means of numerical calculations that the resulting profile of the wind speed based on a two-layer model has evolved significantly at fluxion over a smooth surface, which is caused by not taking into account the rotation of the Earth, and the temperature profile in the course of the calculations. Whereas the logarithmic profile of wind velocity, which is a characteristic of the surface sublayer, does not change in the course of calculations. Keywords: profile velocity, boundary conditions, turbulence coefficient |
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Modern space programs give specialized practical tasks to the developers in order to develop new engines and their improvement. Capillary pulse discharge with an evaporating wall of the channel is a relatively simple way to obtain plasma. It is known that this type of discharge is characterized by a long, relatively stable structure of a pulsed plasma stream in the atmosphere. A capillary pulse discharge is a generator of plasma streams, which is an inter-electrode ins ert made of a dielectric cylinder with an axial bore that is used as a main channel of capillary discharge, electrodes and the body. As part of the radiating plasma dynamics, taking into consideration the radiation transfer, problem is set plasma and gas-dynamic processes in the flame of a capillary discharge with an electrode vaporizing under the assumption that the brightness temperature and the temperature of the outflowing plasma equal to each other. Specific calculations with plasma-forming substance performed for Al flooded space (air under normal conditions), the timing of the maximum discharge current is equal to t_{max} = 25 ms. The val ue of the total energy stored in the buffer storage, was 2,7 kJ, the channel diameter capillary discharge is 10 mm. The numerical solution of the system developed in accordance with the non-stationary two-dimensional radiation magnetogasdynamic model, which is based on the method of splitting into physical processes and spatial directions. The spatial distribution of temperature, pressure and density shown in a quasi-stationary part of the jet, on time t = 94,6 s. The results show that at time of about 100 ms brightness temperatures plummet from 10 to 3 kK and then relatively little change over time. In this paper the results are compared with other calculations and experimental work for the high-current discharge channels [15, 18]. In [15] jet diameter d_{0} = 0,2 cm, the pressure on the cut p_{0} = 143 atm, the axial velocity of the plasma u_{0} = 10,8 km/c, radial velocity v_{0} = 0, the plasma density ρ_{0} = 1,89 ∙ 10^{-4} g/cm^{3}, the density of radiant energy flux S_{0} = 23,9 mW/cm^{2}; environmental parameters were taken to be: p_{∞} = 31,6 bar, ρ_{∞}_{ }= 1,52 ∙ 10^{-2 g / cm3}, T_{∞} = 2,59 ∙ 10^{-2} eV. In [18] calculations Underexpanded plasma jet made for the channel diameter d = 0,2 cm. In the jet nozzle exit temperature T = 3.5 eV, pressure p = 70,8 atm, the density ρ = 1,29 ∙ 10^{-4} g/cm^{3}, velocity u =10 km/c, the Mach number M = 1,24. Parameters of the ambient air following: p_{∞} = 1,63 atm, ρ_{∞} = 1,29 ∙ 10^{-3 g / cm3}, T_{∞} = 0,038 eV. In [15, 18] Mach disk locations after the jet to a quasi-stationary mode does not correspond experiments [8-10]. However, calculations of how [15] and [18] give the same values of Mach disk position. Authors of the experimental work [10] observed two bright glow: have cut the capillary and in the Mach disc, which means an increase of temperature in these areas. This is consistent with the calculations of this study and [15]. Brightness temperature jet, measured experimentally, equal to 23,5 kK [8-10]. Calculated brightness temperature jet differs by more than 10 kK. Numerical investigations of pulse jet flowing through the slice rather «wide», more than three millimeters channels, show that near the boundaries of the jet formed unsteady vortex structures. The work was performed in the framework of the program of the Presidium of Russian Academy of Sciences and the Russian Ministry of Education (Project No. 13.79.2014/K). Keywords: plasma engines, radiation plasma dynamic, capillary discharge plasma jet, the computer system ASTEROID |
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Physical and mathematical model and computational algorithms for the simulation of chemical equilibrium flow in the nozzle detonation engine in quasi-one-dimensional stationary statement. The case of fuel combustion in stationary detonation wave with the subsequent acceleration of the flow to supersonic speed. Investigated flow regimes allowed under the one-dimensional stationary model. Suggested form of presentation of the results of mathematical modeling in the form of the R-R diagram, which allows for the known input parameters to determine the realized type of flow at different ratios between the radii of the input, critical and exit sections of the channel.
The section AB of the curve 6 corresponds to an overdriven detonation wave in the tapered portion of the channel at the point corresponding to the point B corresponds to the mode of Chapman-Jouguet in critical cross-section . With further decrease in the critical radius of the nozzle, the detonation wave of the Chapman-Jouguet is an expanding part of the channel, 0.5, point C corresponds to 0.2, and < 0.2 is the locking of the thread. It should be noted that for the correctness of the model used, the temperature of the flow front of the detonation wave must be below the Autoignition temperature of the combustible mixture. Keywords: numerical simulation of detonation engine, the one-dimensional stationary model, the direct problem of the theory of the nozzle, the equilibrium chemical transformations |
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The paper describes investigations of formation of large-scale longitudinal counter-rotating structures in the airflow duct of the subsonic and supersonic parts of nozzles of jet engines. The reason for their emergence is interaction of impinging jet flows with curvilinear surfaces in the transonic part of the nozzle. The governing effect of the free-stream velocity on the vortex intensity is demonstrated. The presence of spatial structures affects heat and mass transfer, as well as erosion of the inner surfaces of the engine duct. Three types of such spatial structures were investigated experimentally. The first group includes spatial vortices observed in the free space behind solid-propellant charges with star-shaped channels, which were widely used in solid-propellant rocket engines. Based on experimental data, methods of effective suppression of the adverse effect induced by these structures were proposed. Further, the results of ITAM SB RAS studies were considered, where formation of large-scale vortices in the free space behind the solid-propellant charge with a duct having a circular cross section was shown. The presence of solid-propellant charges with channels of different configurations in the engine duct inevitably leads to generation of spatial structures of different intensities. The third type includes large-scale paired vortices formed in the nozzle with a permeable supersonic bell mouth. The following vortex formation mechanism is implied. Zones of gas ejection and injection are formed in the nozzle with a porous wall at a certain pressure in the settling chamber. A change in the flow regime leads to positive curvature of the streamlines. As the gas flow near the wall has a negative gradient ∂u/∂r < 0, this leads to violation of equilibrium between the pressure gradient and the centrifugal force. As a result, instability starts to form in the flow, which is finalized by formation of large-scale longitudinal vortices. Keywords: longitudinal vortexes, jet engine, supersonic engines, stream flows, heat and mass exchange, erosion, vortexes intensity, star shape, ridged surface |
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Aeronautical and Space-Rocket Engineering | |||||||
Aeronautical engineering | |||||||
At present existing of the approaches to the solution of a problem of planning of a route for flight, first of all, need to belong to process of serial flight and supervision of motionless objects. However in these methods the insufficient attention is paid to a choice of a route of flight of the obstacles which are, especially, arising during flight, in other words those, information about which is not laid into the memory of computer (high speed digital computer) before a departure. The special feature of this question in relation to the unmanned aerial vehicles (UAV) that in case of sudden changes of a dynamic situation of flight plan has to be carried out without participation of the person in the automatic mode. The purpose of this work is to develop of the logical control system of route of flight of the unmanned aerial vehicle focused on flight of obstacles in a route information about which is known in advance or comes to flight time, and the planned points of a route are fixed. Is formulated the formulation of the problem of logical control of cross-country flight (UAV) with the circuit of obstacles and are introduced the concepts of most logical control and designation of settings into the regulators of the channels of the longitudinal and yawing motion (UAV). Is developed the algorithm of logical control of multimode over flight BLA of one point in another during the automatic partition of trajectory into a number of sections with its regimes and determination of the boundaries of these sections in the form of the coordinates PPPM (an intermediate point of the planned route), which supplement the list of basic PPM (point of the planned route), entering the flight mission (flight plan). Is shown that at flight of obstacles the developed algorithm in real time forms a piecewise and linear trajectory of round of tops of this obstacle that corresponds to numerous reassignment of settings in regulators of management of lateral motion of (UAV). The computer simulation of cross-country flight taking into account obstacles showed the high speed operation of algorithm on board (UAV), and also the ability to form operational reporting about the facts of encounter with the obstacle, the selection of the version of actions and to report the coordinates of newly assigned PPPM for the delivery(transmission) to the earth. Keywords: unmanned flying vehicle, obstacle avoidance, an intermediate point of the planned route, fixed-route flight |
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Testability analysis is one of the phases of the design process. We examined approaches to the creation of operational model of the plane, its diagnostic model is presented by objects of physical classification breakdown. Testability analysis procedure establishes the methodology and decision making logic, which should be a prerequisite for the determination of maintenance tasks for troubleshooting and disaster recovery facilities top-level control (system, plane) in the event of failure of its components (systems, subsystems, LRU). The publication shows that the testability analysis task is options chosen evaluation and control devices evaluation and their optimality for maintenance tasks. For the plane testability assessment is offered the method of the testability analysis of operational model of the plane, based on application of logical-and-probabilistic simulation evaluation with attraction of the failure tree device. Advantage of such approach is possibility of adequate models creation and carrying out exact calculations of testability indicators on evident and widespread in the theory and practice reliability analysis and aviation-related systems safety. Failure tree models are presented for the analysis of data reliability of integrated control systems, considering functional flavor and robustness of integrated control systems. Unreliability of integrated control systems is treated as possibility of hardware failures like malfunction and false response of integrated control systems. Offers according to the accuracy grade of the integrated control systems (depth of control) in the general expression for an uncertainly control criteria are given. This method offers the approach to the formalized description of information objects control for the automated analysis of the plane testability, based on XML technologies. The universal data model of testability in the form of a XML scheme reflecting three-level operational structure of the plane is developed. Keywords: built in test equipment, maintenance, operational model of the plane, functionally logical model, fault tree, logical-and-probabilistic simulation evaluation, reliability, safety, testability, testability indicators, testability data model, logical-and-probabilistic simulation, XML scheme |
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The article discusses the physical and mathematical models of spatial flight unmanned aerial vehicle helicopter — type drone. These devices have received wide application in various fields of national economy. However, a deterrent to their wider use is the lack of a common approach to defining the shape of the autopilot, allowing purposefully and with acceptable quality to automatically control the flight path of the drone. The investigated materials are intended to define the shape of the autopilot, its structure, basic circuits and their parameters. The physical model of a kvadrokopter considering all main forces and the moments causing him forward and rotary motions is offered. On the presented physical model of the spatial movement of a kvadrokopter mathematical descriptions are developed. According to the presented physical model of the motion of a quadrocopter developed mathematical descriptions. They all control forces and moments are generated by using four Electromechanical DC motors with propellers on their rotors. Forces and moments are created independently by each engine by regulating its speed. In mathematical models the ineradicable interactions between various drives of traction screws having fairly complex character are considered. It is necessary to consider the spatial movement in all six degrees of freedom for more correct description of the motion of a quadrocopter . The peculiarity of the task to be solved was consideration of the dynamics of the actuators, forming the traction forces and moments with the screws. The main contours in the structure of the autopilot: contour stabilization of the angular position of the quadrocopter, the contour of the positioning of the quadrocopter in space and circuit for stabilizing the speed of rotation of the motors, that together purposefully to control the flight path and the angular position quadrocopters space. were considered in the course of research on mathematical models of the dynamics of the movement. Algorithms of realization the control in each of contours are offered. The Suggestions on selection of parameters of contours of control allowing to provide the steady movements of the acceptable quality are given. All offers formulated in work are checked by means of digital computing experiment. The received results allow to develop the autopilot for control of a kvadrokopter with the set characteristics of accuracy and stability. Keywords: quadrocopter, digital model of spatial movement, flight control, autopilot control loops |
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Aerodynamics | |||||||
Method for digital processing shadow images of supersonic gas flowing over aircraft structural parts
The study of gas stream flowing over solid bodies is highly relevant for development of aviation and rocket-and-space equipment. Such research is carried out using unique stand units with flowing visualization. Gas-dynamic flow visualization itself is performed using various equipment and processed using various methods. Shadow and schlieren images are widely known. They are based on the phenomenon of light deflection when it passes through transparent medium density inhomogenuities. When gas flowing field is visualized using the schlieren method, illumination variation is in proportion to gas density gradient in the area under consideration, and when the shadow method applied, variation in the illumination is determined by the degree of density gradient variation. Both the shadow and the schlieren method provide for production of 2D images, which can be successfully used for following up the pattern of gas stream flowing over an object, but are almost useless for quantitative estimation. The purpose of the study is developing a method for digital processing shadow images and determination of the parameter characterizing the image and correlating with the basic gas stream parameters (velocity, pressure and density). Application of this method will allow determining gas flow operational properties (for example, pressure) at any point of the stream, thus making possible the analysis of the respective design solution and choosing its best variant. In this paper image intensity (brightness) is suggested as the basic image analysis parameter. The obtained results contribute not only to better understanding of the physical constituent of supersonic gas flow, but also to determination of the real gas flow intensity values with their further processing by pressure estimation. Keywords: ultrasonic gas-dynamic flow, experimental studies, image intensity, image intensity histogram, pressure, gas flow velocity, compression wave, Mach number, Mach wave |
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Rocket and space engineering | |||||||
Spacecraft mechanical joining during docking is provided by using specialized mechanisms of docking units. These mechanisms may be deformed with hysteresis caused by dissipation of mechanical energy due to internal structural friction. Their deformable elements are complex assemblies composed of a large quantity of parts differing in material and dimensions, or multistage rotation gears with backlashes. The development of a theoretical model of mechanical energy losses in such objects is practically impossible. Simple math models of deformations with hysteresis are considered in this paper. They are based on test data and do not explain the causes of the hysteresis phenomenon. These models are intended for the calculation of reaction forces and moments in mechanism and spacecraft motion equations, i.e. for the estimation of the mechanical energy dissipation effect on docking dynamics. Therefore they have to provide a high computing efficiency for reducing time on numerical integration of differential motion equations. The hysteresis of mechanism stiffness is of a «double loop» type reflecting mechanical energy losses due to internal structural friction forces. Its math models with constant and variable parameters are considered by the example of a simple «probe-cone» type docking mechanism with independent linear and angular deformations. Hysteresis models for other types of mechanisms may be obtained similarly. In the hysteresis model with constant parameters, forward and back loop branches for positive and negative deformations are presented with any necessary precision as sets of straight line segments numbered according to a deformation increase from zero to the maximal value of the permissible working range. Transitions between forward and back branches are described by single straight line segments with maximal slope coefficients. The state of deformation model is defined by the sign (positive or negative), branch type (forward, back or transitional) and straight line segment number that corresponds to a current deformation value. Model state changing conditions are described in a table form. Parameters of transitional branches, with a change of deformation velocity sign, are obtained from the solution of second order systems of linear equations. Hysteresis math models with variable parameters describe deformations of rotation gears with friction clutches. Rotation of the input shaft of such clutch is nonreversible. Therefore arguments of the table description of the stiffness of its input gear are corrected according to the nonreversible rotation angle in case of any change of the rotation rate sign. Parameters of the piecewise-linear hysteresis model are generally determined by static test data of a mechanism or its elements. Adjustment of the hysteresis model can be made by using dynamic test data in case direct static measurements are difficult or impossible to take. Piecewise linear models of deformations with hysteresis are used to describe deformations of various docking mechanisms or their elements. They have a high computing efficiency and appropriate engineering accuracy. The paper presents a comparison of math modeling results and dynamic test data obtained at a 6-DOF hybrid facility, for a «probe-cone» spacecraft docking process. Their good coincidence is particularly ensued from taking into account deformations with hysteresis. The above described hysteresis models based on test data may be used in various engineering applications wherever the effect of this phenomenon on a dynamic process needs to be estimated without explanation of its causes. Keywords: structural deformations, hysteresis math model, docking |
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Aircraft engines and power generators | |||||||
This paper considers questions, related to comparison of different methods for solving rigid systems of differential equations, which describe distribution of a detonation wave in a flat channel of constant cross section. This assignment compares the results obtained by several methods, e.g. Euler, Gear, Pirumov. Thermodynamic method for studying chemical reactions suggests the theoretical possibility of the testing processes under different conditions. If pressure and temperature are constant, then spontaneous process flow is possible only in the direction of reducing the Gibbs energy. However, this condition does not allow to estimate the speed of the transition from the initial to the final. Chemical reactions can take place at different speeds — from slow to very explosive. In some cases it is necessary to increase the reaction rate, in other contrary, reduce. Problems of chemical kinetics is the study of the rate of chemical processes. It is necessary to determine velocity dependence on various parameters for the rational chemical reactions. Modern computer mathematics systems allow to give a quick and clear forecast of the chemical behavior of the system over time. Systems of equations of chemical kinetics contain differential equations, the main feature of which is low sensitivity of the solution in the presence of rapidly decaying perturbation. (Rigid system of differential equations). There are various ways of implementing the software solution of a mathematical model chemical kinetics processes. This assignment compares three methods for solving differential equations, which describe the chemical interaction of the components of the gas mixture in the problem of the distribution of the stationary detonation waves in a flat channel of constant cross section, filled with stationary stoichiometric hydrogen-air mixture. This assignment solves system of equations describing the one-dimensional inviscid steady flow of multicomponent reactive gas mixture behind the shock wave propagating with constant velocity D. To close the system uses thermal and caloric equation of state of the combustible mixture, which is a mixture of perfect gases. According to comparison, Pirumov’s method requires the smallest number of steps for all velocities behind the shock wave. All calculation methods showed fairly similar results at speeds approximately equal speed Chapman Jouget, but Pirumov’s method gave the solution with the least amount of steps. Comparison also showed that Gere’s method gives a solution quickly than Euler’s method at all speeds. Keywords: rigid system of differential equations, numerical methods, equations of chemical kinetics, detonation waves |
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The problem of reducing the hydrodynamic vibration of pumps of LRE feed system is the key issue to improve the reliability and service life of propulsion unit. In this regard, the actual task is modeling pressure pulsations in the flow path and the pump hydrodynamic vibration at early stages of turbo pump unit design. The article deals with numerical simulation of three-dimensional unsteady turbulent flow in the booster pump unit of liquid rocket engine. The analysis completed of the spectrum composition of pressure pulsations occurring in the flow path of the pump unit. It is found that pressure pulsations spectrum at the outlet of the working screw includes the tonal component on the blade passing frequency (BPF) and its harmonics. At the screw inlet pressure pulsations spectrum tonal components with rotor frequency and BPF dominate. It is found that pressure pulsations at the screw exit is the result of rotor-stator hydrodynamic interaction; pressure pulsations at the screw inlet are generated by the uneven pressure field, which is enhanced by hydrodynamic interaction of wakes from pylons terminated by the radial gap leakage flow from passing screw blades. Numerical modeling of the pump casing vibration begins with definition natural modes and frequencies of mechanical oscillations. Modeling of the forced vibrations of structural elements and the pump casing ensures assignment of distributed dynamic loads from the pressure pulsations. Comparison of the computational results and experimental data suggests that the proposed approach can be used by designers when developing pump units. Keywords: axial screw pump, pressure pulsations, finite volume method, three-dimensional flow modeling, LRE booster pump unit, spectrum composition, natural modes, forced oscillations, BPF |
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The article presents the investigations results of the most effective electrolyte-cathode compositions searching for hydronic chemical current source (CCS) with an aluminum anode. We examined current-voltage characteristics (CVC) of some metals and alloys — nickel, molybdenum, titanium, and steel Ст3 in purely alkaline electrolyte (4 M NaOH), and in alkaline electrolyte with addition of sodium stannate: 4M NaOH + 0,06M Na_{2}SnO_{3}∙3H_{2}O. This alkali-stannate electrolyte has been sel ected for research because it is the most effective in terms of alkali aluminum anode corrosion inhibition in air-aluminum (AA) CCS with a gas diffusion cathode (GDC). The best CVC in pure alkaline solution were obtained for molybdenum and nickel. However, molybdenum as the cathode showed a high tendency to hydrogen embrittlement. After a series of cathode tests the electrode made of molybdenum foil (0.1 mm) collapsed when installed in the test cell due to the small deforming effects. In the alkaline-stannate electrolyte CVC of cathodes made of different metals were significantly deteriorateв due to the formation of the tin coating on the surface to a different degree, especially in prolonged and/or repeated use. To explain the causes of different degree of potential reduction we carried out the structure investigations of the formed coating in the alkali-stannate electrolyte of electrodes made of various metals. The investigations were made by X-ray diffraction and scanning electron microscopy (SEM). The surface of nickel electrode was studied. The electrode was tested as the cathode for three experiments in a row to obtain discharge characteristics of a hydronic CCS in a cell with an anode fr om an Al-In alloy. Stationary discharge current was set to 1000 A/m^{2}. As the experiments showed, the structure of the tin coating formed on the electrode surface is porous with a high degree of porosity (~ 50%). It causes the difference in the CVCs of cathodes of different metals due to hydrogen evolution, both on the surface of the substrate (base material), and on surface coating. Thus, it is shown that the use of stannate ions additives to the alkaline electrolyte of a hydronic CCS is undesirable, since it leads to deterioration of cathodes’ characteristics. Therefore, for inhibiting of the aluminum anode corrosion and, thereby, for increasing its use factor, it is necessary to introduce additions of organic inhibitors in an alkaline electrolyte of a hydronic CCS. Keywords: chemical current source, power plant, hydrogen generator, corrosion inhibitor, corrosion characteristics |
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Instrument making, metrology, information and measuring equipment and systems | |||||||
Instruments and control methods of environment, substances, materials and products | |||||||
Experimental studies of the properties of radio-absorbing materials and coatings to solve the problem reducing the radar visibility of aviation complexes occupy a unique position. Foreign and domestic experience shows that without development of laboratory-polygon base to achieve significant results on this issue is impossible. One of the main problems in experimental research within the problem of reduction the radar visibility is the study of electro-physical parameters of radio-absorbing material such as, complex permittivity and permeability, wave resistance and coating thickness. The purpose of research is to develop a laboratory stand for research of electrophysical parameters of radio-absorbing materials and coatings. The principle of operation of the laboratory stand is based on the effect «spill» slow surface electromagnetic waves on a plane surface and scan results from the interaction of the field with a coating layer in the functions of the complex electro-physical and geometrical parameters (permittivity and magnetic permeability and thickness of the coating) As a result of theoretical and experimental studies designed laboratory bench for the study of electrophysical parameters of radio-absorbing materials and coatings. The advantages of the proposed device is to provide non-contact measurement, high efficiency and accuracy of measurements, a large number of simultaneously monitored parameters, low cost primary transmitter and at least elements of the device. The resulting specifications developed by the laboratory stand can effectively use it in the study of electro-physical parameters existing and emerging models of radio-absorbing materials and coatings aviation complexes . Besides laboratory bench can be used as a basis for the design and development of modern equipment for controlling the parameters of radio-absorbing materials perspective aviation complexes with reduced radar signature. Keywords: radio-absorbing material, radio-absorbing coatings, measurement, electro-physical parameters, radar cross section, laboratory stand |
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Information and measuring and control systems | |||||||
The work is dedicated to the creation of the camera stabilization and control system, located on board of the unmanned airplane with take-off weight not exceeding 15 kg. The task was to improve features of video shooting to the large range of angles at which the camera can be rotated with respect to the aircraft. Thus, it was important to provide a mode in which the camera is able to film even in the upper hemisphere of the aircraft at angles up to + 20˚ above the horizontal plane, while in most UAVs camera overlooks only the lower hemisphere. The main objective was to maintain the video camera, installed on board the UAV, in a given direction when maneuvering in the air. To solve this problem was performed as follows: — the controller, position sensors and acceleration were set; — the motherboard with the necessary inputs and outputs were set up; — a mathematical model of the aircraft, algorithms and programs for controlling the position of video camera were developed; — the regimes of observation «In the direction», «At the rate» and «Tracking point» were realized; — possible to change the settings of Camera: aperture, shutter speed, focal length, etc.; — given mass-dimensional characteristics were kept up; — the camera functions control was provided to the operator in real-time. The block of video camera was built into the fuselage of the aircraft. Whole device fits into a cylinder with a base diameter of 0.15 m and height 0.15 m. One of the main tasks was solved — to make the camera independent of the inertia of the aircraft. Low-inertia precision solenoid motor rotates the camera head around each axis. The range of variation of the angles of the first axis: ± 180°, on the second axis: between +20° to −120°. Created system allows you to shoot along the longitudinal axis of the aircraft and to view the upper hemisphere. Stabilization of the camera head is performed by a PID controller. The complex is able to solve problems of finding people, detection of fires in the forest and, of course, the problems of intelligence service. Keywords: unmanned aircraft, unmanned aerial vehicle, UAV, aero video shooting, stability of flight, programmable controllers |
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Most of aircrafts in aviation and aerospace can be represented as a combination of two main components: the technical part — the mechanisms of varying complexity, and the team of aviation specialists (pilots, astronauts, navigators, air traffic controllers) that control the aircraft and supporting their performance. To ensure the control of aviation specialists physical state (PhS) we should use special wearable devices of microelectronics (WDM), implemented in the form of smart bracelets, watches, lenses or glasses and the elements of smart clothes. Controllable WDM data (heart rate, blood pressure, muscle strength, and others) are transmitted to the data center (DC) as a part of a hardware-software complex «TsifroMed» using techniques of biofeedback (BFB) which representing a man as a biological control object. The system «TsifroMed» collects and analyzes the data from WDM and provides a team of analysts a wide range of capabilities for monitoring, coordination and communication with the aviation specialists: emergency medical assistance, alert other crew members PhS of aviation specialists (in particular the pilot), change tracking PhS during continuous operation, the detection of abnormalities in the preparatory phase of the pilot and providing an immediate impact by sending signals to the elements of smart clothes etc. The study focuses on a team of aviation specialists (the interaction and communication with them) and continuous monitoring of their PhS, to minimize the risk of accidents and air crashes caused by human factor. Such monitoring will reveal a variety of problems, such as during the preparation of aviation specialists, and in the course of their work, for example, reveal the impossibility of transferring physical overload fighter pilot or astronaut to maintain the health of muscles during long-duration space flight. The basis of system «TsifroMed» is a three-tier architecture — an architectural model that assumes the presence of three components: 1) the client (the client layer as user interface); 2) application server (logic layer as program modules and data handler); 3) database server (data layer as store large amounts of data). The study notes the particular importance of monitoring the physical condition of aviation specialists, both at the stage of their preparation and at the stage of execution of their duties as pilots, astronauts, navigators, air traffic controllers and others. To solve the problem, we developed a prototype of information system «TsifroMed» (as a hardware and software system) that provides continuous monitoring of the physical condition of aviation specialists on the basis of indications of portable devices using microelectronic technologies of biofeedback. Implementation of «TsifroMed» in the aerospace industry would minimize the risk of accidents and air crashes caused by human factor, to exclude a variety of risks, such as those associated with large congestion or long stay in weightlessness and improve the training quality of future aviation specialists. Keywords: aviation, aerospace, hardware-software complex, architecture of information system, wearable devices of microelectronics (WDM), biofeedback (BFB) |
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Radio engineering and communication | |||||||
Radio engineering | |||||||
The paper proves the topicality of assurance of signal integrity in spacecraft autonomous navigation systems. As it is important to achieve import substitution and technological independence, we propose to use domestic system of computer modeling of electromagnetic compatibility. We provide results of analyses of various circuits of real printed circuit boards of spacecraft autonomous navigation systems with and without estimation of losses and real loads in time and frequency domains. The analysis is carried out by means of quasi-static approach implemented in the TALGAT software. Three illustrative cases are examined. Firstly, influence of boundary conditions on the wave form in the coupled lines was evaluated with and without estimation of losses in the conductors and dielectrics. We revealed that mismatching of a line at the beginning and at the end leads to the big number of reflections, which can be used for correction of the signal rise time degradation due to the losses in real interconnects. Then, we evaluated the level of crosstalk and the transmission coefficient in the five-conductor line in time and frequency domains. The worst case is when one conductor is being simultaneously affected by all others. As a result, we obtained high level of crosstalk, at the near end it is 6.5% of the signal level in the active line, at the far end it is 2.8%. Simulation in frequency domain showed that the first crosstalk maximum in the passive conductor is 20% of the signal level in the active line, and it can be seen at the frequency close to those of the navigation systems. Finally, evaluation of synchronization of signals in the differential pair was carried out. The obtained difference of the signals is rather big, 3.5% of the signal in the active conductor. Keywords: simulation, electromagnetic compatibility, signal integrity, printed circuit board, onboard electronic equipment, autonomous navigation system |
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The article considers the approach to solution of the problem of production method options selection applied in assembling electrical components on a printed circuit board (PCB) implementing a knowledge base and expert system. The study aims at creating the software providing process design allowing automatize the primary information processing on the parameters of production methods options realization. Introduction of expert system to the software was made necessary due to the need to analyze interrelated factors, affecting the effectiveness of a technological process. All the factors were combined into eight groups with in accordance calculating assignments. These groups of factors generate libraries of basic program classes, which encapsulate inside the main features and methods of production methods parameters processing. The interaction of these classes is realized through the external memory (blackboard), where the values of all parameters of a production method are stored. The study considers the example of implementation of the suggested model for estimation of selection of the equipment for radio components on PCBs according to the effective items peak output criterion. The parametric model of assembly errors contains four logically interconnected models: component model, PCB model, assembly robot model, and technological operation model. Each of the models determines analytical and logical dependencies of the factors affecting the effectiveness of a production method, and is represented in the program complex by the class. The developed mathematical models are generic models for prediction of production method of PCB-based units’ efficiency. They allow perform calculations of quality evaluation and production method options selection according to reference books data (components structure, equipment parameters and materials) The knowledge base in the form of library of classes provides opportunities to expand the functionality of the software for optimization of technological preparation for assembling PCB-based units. The output of expert system provides optimization problem model in canonical form, which is used in the optimization algorithm The suggested approach is experimentally and small-scale production oriented, where the performance of highly costed analysis is limited by financial resources and the lack of qualified specialists. Keywords: the expert system, knowledge base, technological process, software complex, equipment, quality criterion, constraint, airborne radio equipment |
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The system approach in the course of the development of radio technical systems allows significantly reduce the development time and cost by using the modules of different production readiness [1]. The basis of information support of such of design systems is a database (DB), which is used for storage and selection of both parametrical models of the RTS modules, and parametrical models of the whole projects of Radio-Technical systems (RTS). Thus, a need emerges to carry out conversion of parametrical models of modules and their characteristics from the module storage format into the project storage format. The execution time of procedure of modules converting in many respects depends both on DB’s creating, and on algorithms of performance of the separate functions, included in the procedure. To reduce the time of the converting procedure and thereby improve performance of the whole CAD is possible by using of the capabilities of modern databases. Particularly, it is possible to use one of the two methods of creating of D. B.— by using cursor or temporary tables. In the first case cursor, which represents the area in random access memory of the D. B. server to which all selected component modules are successively stored. In the second case, the parameters of the selected modules are stored in the temporary table. The conversion procedure is reduced to assigning to each module a unique composite key that corresponds to the format of the current project. For a large number of convertible modules the second case is preferable since using the cursor process of converting is carried out sequentially (line by line). That increases the time of conversion. The most resource-intensive part of the process of conversion is a function of performing a hierarchical query. For creation a hierarchical query, it is possible to use such method as «parent/child» or method, which uses the type of data of HierarchyID [4, 5]. The main advantage of the HierarchyID method in comparison with the method of Parent/Child, is the ability eliminate the cycles and recursive queries CTE, which implementation consumes a lot of time. Particularly, when the number of modules (N) equals 10000, the time of query execution with the HierarchyID method, will be 15 times less, than in the first case. Therefore, this method is useful for a large number of modules, included in the hierarchical tree. Thus, based on our research, we can conclude that the implementation of the conversion procedure for large Ns (N > 1000), to improve the performance of date support CAD it is reasonable to use DB with temporary tables, and while executing hierarchical query — a method, that uses the data type HierarchyID. At the same time, with a small number of modules (N < 1000), both during convertsion procedure realization, and executing hierarchical queries, D. B.’s performance does not significantly depend on its structure. In this case, it makes sense to implement D. B. with simpler structure realization, such as, with the cursor using, and to execution of hierarchical requests — the Parent/Child method. Keywords: Computer-aided design, CAD, Databases, Hierarchical queries, Converting module components, Query optimization, Radio technical systems |
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Signal-to-noise ratio estimation plays significant role in state of art communication, navigation and location systems. Signal-to-noise ratio affect performance of these systems and its estimation can be used to control systems and adopt its characteristics for various conditions. The paper presents a comparative analysis of various signal-to-noise estimation algorithms. These algorithms based on quadrature components of the received signal. Considered the quality of operation of these algorithms in two cases: when the phase synchronization has zero error, and when there is a various fixed error. All considered algorithms can be divided into two categories: based on in-phase and quadrature components itself and based on received signal vector length. Analysis performed for channel with additive white Gaussian noise and binary phase shift keying modulation. MATLAB/Simulink software used to simulate realizations of algorithms in described specific environment. Algorithms accuracy analysis obtained for 10% maximum error. The results of the work can be concluded as follows: all considered algorithms have estimation errors for signal-to-noise ratio of less than 10 dB; the minimum level of these errors can be achieved with algorithm (2.31); algorithms, that are effective in the presence of phase synchronization error, and algorithms, that are effective in the case of zero phase synchronization error, can be selected; algorithms based on received signal vector length are resistant to phase synchronization errors, but they have highest errors in less than 10 dB area. Keywords: signal-to-noise estimation, simulation, MATLAB/Simulink |
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In this article we consider the problem of optimizing the production capacity of the serial and pilot manufacturing of high-tech products characterized by urgent and unpredictable nature of orders, and the need for prompt release of prototypes and pilot batches of products for testing and debugging. To optimize the level of capacity and equipment performance in the field of serial production we propose an adapted model of multi-channel queuing system with a queue. Among the losses due to expectation lags are also taken into account logistic losses caused by storage of expensive component and work in progress. We optimize both the number of service channels and their characteristics (from a discrete set of options), which allows to optimize the parameters of the production equipment and technology, and to assess the effectiveness of flexible equipment and technology implementation. We compose a model of a new product release process consisting of two stages: the development of pilot production and mastering of serial production. We take into account that the latter costs less. We formulate a problem of finding the optimal ratio of the serial and pilot production levels. Using the developed mathematical models and optimization methods, we carry out parametric calculations using measurable technological parameters one of the high-tech industries. It is shown that in this industry even a significant redundancy of capacity of serial production (up to 20-50%) may be optimal, and such a redundancy allows to increase the expected profits of enterprises for a 10-20%, and to reduce significantly (30-50%) the orders execution duration. The optimal level of pilot productions’ capacity can reach 20-50% with respect to mass production, but only under the condition that pilot production provides a significant — 3-5 times — reducing the time of pilot batches production, and the increase in costs will not exceed 20-30%, compared with mass production. The developed methods and models require only measurable initial data and can be used in various industries to optimize the level of production capacity, characteristics of the production equipment and technology. Keywords: production facilities, prototype and mass production, modeling, optimization, queueing system |
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Antennas and SHF-devices | |||||||
Controlling devices for microwave range with semiconductor elements (SE) are intended for controlling amplitude and phase of signals, and switching signal for different channels commutation. Controlling devices include breakers, electrically controlled attenuators, multiple channel switches and switching matrixes, phase inverters. Recently p-i-n diodes and field-effect transistors with Shottky gate are used for controlling devices, including multiple channel switching devices as SE. The multiple channel switches can be implemented as series, series-parallel and parallel cut-in SE inline. The channels of the switches can bifurcate both from one point, or consist of consecutively bifurcating switching groups, in which case they have a more broadband operational frequencies. The necessary condition for creating the switches for increased power level is a compensational capacity of reactive parameters of SE in the structure of the switch. The capacitance compensation of the semiconductor structure allows use SE with smaller impedances in on- and off-mode, to reduce the power dissipation in SE, raise rated dissipation power and, consequently, raise significantly the microwave power commutated by the switch. This report analyzes the main circuits of the multi-channel switches, their advantages and disadvantages. It shows that using the broadband structures with short-circuit and open-circuit stubs in different circuit designs of the multi-channel switches allows increase the operating frequency range, reduce the open channel losses, enlarge the closed channel decoupling, increase the level of commutated microwave power. The improvement of electric parameters of switches is connected with proposed circuit configurations, which allow compensating input reactive conductance of stubs, short-circuits and SE, connected to transmission path of the open channel. Keywords: shunting structures, switching devices, semiconductor elements |
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Systems, networks and telecommunication devices | |||||||
This article presents the design of optimum WLAN-Settings for maximum throughput or respectively minimum of collisions in a WLAN over fibre system. Although it is shown that the fibre delay might violate some of the timing boundaries of the media access (MAC) protocol, with a careful choice of slot time, these networks can benefit even without the need for modifying the existing protocol. The network topology is based on a WLAN-Environment that is used in a subway in Nanjing (China) to accomplish the Trainguard MT System. Radio over fibre (RoF) technology enables both, distribution of wireless signals over long distances and reducing costs of antenna sites, since the signal processing can be done at a central point. The 802.11 standards were developed for WLAN’s which operate in relatively small areas, where no significant signal delay occurs. Normally the propagation delay in air is much smaller than 1 µs. In WLAN over fibre systems additional delay time occurs. The propagation time is the sum of an air propagation delay and the delay caused by the propagation through the fibre. In continuous communication or point-communication conditions, Siemens Automatic Train Control (ATC) system ensures train safety and continuous supervision. The safety of train separation is based on the moving block principle. The ATC sets two terms on data stream. The throughput for the ATC has to be 10 kBit/s for downlink and 1 kBit/s for uplink, and every transmitted frame must not be older than 10 ms. There are two typical frame sizes used by the ATC system. 30% of all frames are 170 Byte in size and 70% are 220 Byte in size. The used WLAN standard is 802.11b, therefore the maximum throughput is 11 MBit/s. The simulation results have shown that WLAN over fibre can only be realized with the change of slot time depending on the length of fibre. For demonstration that there are too many collisions without the change of the slot time, another simulation has been performed. The result fr om a simulation shows wh ere the slot time has not been changed. Especially the retry-counter reaches often its maximum value, which leads to the fact that frames were discarded. As a result the ATC system fails because now many frames have not been transmitted within a period of 100 ms. In summary, it can be stated that without a change in slot time there are too many collisions, thus leading to a system failure. Therefore the slot time is enlarged by the latency time. Thus, finally it has been proofed that a common MAC-Layer can be used in a WLAN over fiber scenario. Keywords: wireless Local Area Networks, reliability, cost-effectiveness, network topology modeling |
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Telecommunication technologies | |||||||
The effective signs search for an onboard systems states assessment is the important trend of technical diagnostics. It is especially actual in the conditions of emergency functioning. The results of various flight tests of space-rocket hardware allowed obtain acceptable statistical material, showing that temporal rows of telemetric parameters of onboard dynamic systems in the conditions of emergency functioning are characterized by existence of different trends, noises and jams. To detect such features of temporary rows it is possible to use methods on based on RS-statistics and Hurst index calculation. The developed algorithm of diagnostic signs formation includes Hurst evaluation in an «observation window» on temporary rows on the set of telemetric parameters; smoothing of the received Hurst indices estimates within «a smoothing window»; determination of the distribution law of diagnostic signs on telemetric parameters realizations; formation of confidential intervals (admissions) on the received diagnostic signs; optimization of algorithm parameters. The formed diagnostic signs were used for processing of onboard dynamic systems telemetric parameters of the carrier rocket and the small spacecraft. The possibility of clustering of the proposed diagnostic signs for telemetric parameters of one or several similar objects was shown. The analysis of telemetric information with use of the offered diagnostic signs allows detect differences between states of onboard dynamic systems, including conditions of emergency functioning. The used approach combined with classical methods has to increase efficiency and reliability of the automated processing of telemetric information of the space-rocket hardware objects. Keywords: dynamic system, telemetric parameters, Hurst index |
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Article is devoted working out of program models of the communication channels in Simulink. Models are intended for the analysis of reliability of an information transfer by preparation and start-up of rockets of space appointment as processes of updating and re-equipment of starting complexes demand support of high quality of the information exchange, considering features of functioning of the automated systems of preparation and start-up. At construction of communication channels models in Simulink library Communications System Toolbox blocks, and also blocks of subsection Ports&Subsystems have been used, allowing to model a feedback and the duplicated channel by means of such algorithmic designs, as a cycle with a postcondition and conditional transition. The program model of the communication channels with a solving feedback in Simulink is developed, allowing to analyze reliability of an information transfer with application of the codes which are finding out errors. The program model of the duplicated channel of an information transfer with a solving feedback in Simulink is developed, allowing to analyze reliability and a continuity of process of an information transfer. The developed models can be used for formation of statistical data necessary at an estimation reliability of an information transfer and definition of dependence of values of indicators of reliability from parameters of a transferred file, characteristics of the channel with noise, algorithms of coding and decoding. The offered models are intended for carrying out of computer experiments within the limits of educational process and research work, and also for perfection of knowledge in the field of the theory of an information transfer and skills of modeling of information-operating systems. Keywords: the automated system of preparation and start-up, the communication channel, reliability of an information transfer, imitation model, a cycle with a postcondition |
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Radiolocation | |||||||
Growth of intensity of air traffic and requirements on its safety leads to increase of requirements on support of trajectories of aircrafts on all sites of flight, including zones of intensive maneuvering. The particular interest is represented thereupon by multiple model algorithms. Multiple model methods have been generally considered the mainstream approach to maneuvering target tracking under motion-mode uncertainty. Aircraft movement is described by several models of possible movement. For example, for civil aircrafts at the description of horizontal movement three models are usually used. The first basic model is uniform movement. The second model is turn (circle movement). The third is change of speed. Aircraft tracking is carried out under the information fr om surveillance facilities. Today the primary and secondary surveillance radars are used. The general approach to the solving of a problem of aircraft tracking is the description of its movement by several models. Target tracking is a hybrid estimation problem. The condition vector describing coordinates and parameters of aircraft movement has the discrete parameter. It is interpreted as an index of model of aircraft movement. This parameter is described by a Markov’s chain with the matrix of probabilities of transition from one condition to another. In the literature the formal conclusion of the algorithm describing change of density of distribution of probabilities of a condition vector is spent. The target motion-mode uncertainty exhibits itself in the situations wh ere a target may undergo a known or unknown maneuver during an unknown time period. In general, a nonmaneuvering aircraft motion and different maneuvers can be described only in different motion models. The use of an incorrect model often leads to unacceptable results. A primary approach to target tracking in the presence of motion-mode uncertainty is the so-called multiple model method, which is one of the most natural approaches to hybrid estimation. In practice, constructive algorithms are based on a Gaussian approximation of the density distribution of probabilities function. Usually it is interpret as linearization. Block diagrams of three types multiple model algorithms are presented. Comparison of their characteristics was made. Results of simulations are presented. Keywords: tracking, a multiple model filtration, radar |
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This paper discusses the calculation method of spaceborne synthesised aperture radar (SAR) eclipsing and nadir return graphs in MATLAB. Spaceborne SAR systems operate in conditions of effect of blind zones and nadir returns presence. The correct selection of the period of repetition frequency of the probing signal allows reduce the effect of these factors on the echo-signal. However, distribution of these factors depends on slant range and spacecraft orbit height. Theses parameters, in turn, depend on the height of the terrain. The paper presents geometric relationships of SAR side view including orbit high changes and height of the terrain. Signal timings of probe, echo and nadir signals are set out. Eclipsing and nadir return graphs are calculated and built using MATLAB functions. Graphs were plotted as functions of slant range and repetition period. The effect of terrain and elevation changes of the orbit of the spacecraft on the position of eclipsing and nadir returns zones on graph were studied. Linear dependence between slant range and repetition period for boarders of eclipsing and nadir returns zones was found. An analytical dependence between number of eclipsing and nadir returns and their positions on graph was established. The results of graphs calculations in MATLAB and using analytical dependences completely coincide. Thus, presented analytical dependences help to calculate positions of eclipsing and nadir return zones on graphs much easier and quickly. For example, these analytical dependences can be used to produce an on board algorithm of spaceborne SAR probe signal repetition period calculation. Keywords: synthesised aperture radar, blind zones, nadir returns |
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Purpose The article is dedicated to the development of methodical approach to the evaluation of the usage of the exterior radar system as light source for the multiposition radar system (MPRS) in conditions of lack of prior data about the light source coordinates. As an uncooperative transmitter there was considered RS AN/APY-2 of the plane of long-distance radar detection and of system control AWACS. Design/methodology/approach Here were evaluated the possibilities of radar facilities in the survey of sizes and position of working zone. Working zone of MPRS is determined by the light source as the crossing of detection zone and position finding zone. We indicated relations for the evaluation of position finding zones, detection and working zone by the light source using goniometrical and differentially-ranging methods of coordinates calculation. Condition of using possibility of uncooperative transmitter as light source of MPRS and forming of initial data for the calculation of the working zone of the system is belonging of the coordinates of light source to the working zone. If the light source is within working zone then it’s possible to form initial data for the calculation of working zone by using targets. Otherwise, it’s necessary to reduce requirements to the indices of detection quality and accuracy of measurement of light source coordinates. Findings/Originality/value The suggested methodology of designing of working zone of MPRS by the uncooperative light source allows evaluation of possibility of its usage in multiposition RS and differs from the known in the lack of prior data about exterior light source coordinates. Keywords: position finding zone, detection zone, working zone, multi-position radar system, uncooperative exterior source of light |
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Radio navigation | |||||||
Currently there is a rapid development of satellite radionavigation systems (RNS), which stimulates not only civil but also military needs. Therefore, in situations of conflict arising the need to counter satellite RNS. The purpose of counteraction is to create difficulties for the successful solution of the navigation issues in the enemy consumer equipment of satellite RNS. Counteraction to consumer equipment of satellite RNS may be achieved by creating anti-navigation field (ANF) for solving tasks: 1. Counteractions to dangerous objects equipped with the apparatus of satellite RNS by electronic countermeasures (ECM). For the solution of such tasks the spatial area within which objects are located and neutralized must be known. 2. Protection of own objects fr om weapons guided on these objects through the information received from the equipment of satellite RNS by ECM (object protection). Usually initial data for the organization of the object protection are coordinates of protected objects, possible kinds of weapons and also dangerous directions of attacks. 3. Protection of area (region, several regions of the country) from any weapon equipped with the apparatus of satellite RNS by ECM. This task is comprehensive. Solution of one automatically means solution of the private tasks 1 and 2. Particular interest is the evaluation of possibilities of creation of the ANF for the protection of the territory. Traditional approaches for the object protection in this case are unacceptable. The approach based on joint using of jammers and spoofers in the ANF is suggested. The advantage of this approach lies in the facts that basic energy costs are used for the creation of the ANF in the barrier zone, wh ere jammers are located, and in the rest of the protected area low power spoofers are located, which provide sharp decrease of summary energy costs for the creation of the ANF. Keywords: consumer equipment, satellite radionavigation systems, anti-navigation field |
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Informatics, computation engineering and management | |||||||
System analysis, control and data processing | |||||||
The paper presents the algorithm of response speed optimum position control in the form of an air-balloon movement control problem. As a mathematical model, a solid body suspended on a cord and able to perform rotational movements is used. The upper end of the cord is fixedly mounted and operated with two fan motors, generating the opposite control moments about the vertical axis. The body is subjected to the torque, which is linearly dependent on the angle of rotation caused by an elastic cord and the moment of viscous friction, linearly dependent on the angular velocity. It is assumed that the engines instantly gain momentum, and influence of the running engine center of gravity is neglected, The atmosphere is considered to be stationary and homogeneous. This model is described by linear discrete-time system with polyhedron set of the feasible controls. The subject of discussion is problem of zero-controllability of linear discrete-time system with the bounded set of feasible controls, i. e. the problem of transfer the given system to zero by means of feasible control in minimum number of steps. Specificity of zero-controllability problem for linear discrete-time systems is related to the difficulty of using conventional methods. These features is characterized by lack of explicit form of solver of the problem with dynamic programming and lack of analogue of Belman’s equation, incorrectness of maximum principle for minimum time problem in discrete-time case, non-uniqueness of optimal solution. The solution of the problem is based on the conception of a zero-controllability set in N steps, i. e. the set of points from which the system can be transferred to its origin by no more than in N steps, using a certain number of control actions. It is proven, that in this case the zero-controllability set is a convex compact polyhedron that can be represented as the algebraic sum of other polyhedrons. The algorithm of constructing faces of a zero-controllability set in any N steps is developed. The method of computation of minimum time for reaching the origin from any initial state based on exact description of zero-controllability sets is constructed. While the optimal feedback control has explicit form if description of zero-controllability sets is available for any step. At last, the considered problem of the construction of the minimum time air-balloon movement control is completely solved by the investigated methods. Keywords: linear discrete-time control system, minimum optimal response time control, polyhedron, linear programming |
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Consider the problem the problem of searching for optimal from the point of safety of bomber in the bombing on a protected ground aim command vector on the basis of constructing a mathematical model of a two-step algorithm of making a decision is considered. For this the brief substantiation of the choice of a stochastic model for the first step of the algorithm is given, the problem of constructing a payoff function for the second step is considered in the work. A program with test examples demonstrating the operation of the algorithm with real data set is made on the basis of the primary model. Due to the specificity of such systems the question is broached of connection of continuous and discrete systems which has raised a large number of important problems in such priority area for the country as aviation technologies. As a result of the construction of a formal model, a part of the software package was written, which is responsible for finding of the optimal probability of safe target hit. Based on the input of instant tactical situation, the dynamics of flight and data on the impact zone, a probabilistic assessment of the effectiveness of getting into this area is built, as well as the assessment of the effectiveness of the scatter fragments based on preselected mechanical model of bomb explosions. The program builds a possible strategy by combining all the defined actions of releasing the bomb. The payoff function, which is basically a preference relation on fuzzy sets, sets encourage or punitive terms for each situation on a set of pairs of strategies and combinations of all set in the program of discrete and continuous parameters that are sampled for the ultimate goal. As a result, the optimal strategy, if it exists, is displayed for recommendations of dropping the bomb. Except for the specific settings reset, three main situations are considered: reset is not recommended due to the low probability of falling into the impact zone; reset is not recommended because of the risk of the process; reset is recommended, and reset parameters are available to the pilot. Note that most of the research carried out in this paper is devoted to the building of preference relationships for the construction of the payoff function. As the main results can be noted following things. After the analysis of «Bomber — Air Defense» interaction system a primary decision-making model for instant tactical situation was founded, as well as the software package piece responsible for the search of the optimal strategy. Keywords: onboard software, geometric probability, effective engagement |
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The solution to the PID-controller optimal parameter search for the flight control problem for a given set of initial states and the set of input signals is obtained. An algorithm and software is suggested. The novelty of the approach is to add the term with the second derivative of the error and to calculate the integral component not on the whole time interval, but only on an interval defined by a «memory» of the system in the application of the optimality criterion controller parameters characterizing the average cumulative error with respect to the set of possible initial system states and set of input signals. The problem is solved as an unconstrained minimization problem for a function of several variables using the method of simulated annealing followed by refinement of the result by adaptive random search. Solve the problem of finding optimal parameters of the PID controller for the longitudinal motion of the aircraft is given. A comparative analysis of the impact of the controller parameters on the quality of transition process and appropriate recommendations are made. The software, which has a modular structure and user-friendly interface and implements the proposed procedure for solving the problem. This software allows you to arrange the results in tables and graphs. This paper shows that the proposed technology solutions and the corresponding software can reduce the value of the criterion, as compared to its initial value, and improve the quality of the transition process. The suggested technology of solution of the parametric synthesis problem can be useful for solving of engineering problems by construct of PID-controllers.Keywords: PID-controller, optimization criterion, set of initial states, set of input signals, simulated annealing method |
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Control automation of technological processes | |||||||
Automatic control system is an integral part of any modern manufacturing techniques. Prepreg technology of production of composite materials is by far the most common and used. Prepregs for advanced composite materials, both structural and functional, are produced by various methods with a high degree of automation. However, there are a prepregs, production of which, even today, is the long method of impregnation of workpieces by immersion in the impregnating composition. This duration is due to the high requirements on the content of polymer in the prepreg and the uniformity of its distribution. To accelerate the technological process of manufacture of the prepregs MSFU jointly with ZAO ZEM of RSC Energia. S. P. Korolev was developed vacuum technology repeated impregnation with intermediate vacuum dryers. However, the method of control of polymer in the prepreg is proposed in this technology not provides high accuracy and process automation. The article describes the method of automatic control of the production process of a prepreg for the implementation of this technology. Control method is the constant monitoring of the weight of the impregnated preform on stages vacuum impregnation and vacuum drying. This allows from the mass difference, measured after a specified period of time, to determine the amount of impregnating composition arrived in the impregnation or the quantity of the removed solvent by vacuum drying. For the implementation of this method uses a special impregnating chamber, equipped with a weighing system billet-based force sensors and the control system, which, by the calculated values, produces the inclusion of modes of vacuum impregnation and drying of the workpiece. For this, the system has various control circuits. The loop of temperature control maintains a constant temperature in the impregnation chamber. The loop of pressure control by opening and closing the electromagnetic valves connected to the vacuum line and the atmosphere, creates the necessary pressure chamber for the flow of process vacuum impregnation or vacuum drying of the workpiece. The contour control valve binder is using a servo drive to control the amount of binder which comes in workpiece that allows you to set a predetermined rate of impregnation. The article presents the algorithm of the system control that can be applied in the software implementation. Thus, the method of automatic control of the process of manufacturing the prepreg allows with high accuracy to control the parameters of the prepreg by to the content of the polymer and to smoothly control the production process to obtain the best distribution of the polymer on the area and the thickness of the prepreg. Keywords: control method, prepreg, vacuum impregnation, fiberglass, composite |