2015. № 81
Fluid, gas and plasma mechanics
In last time, there is very great interest to the study of differential equations of fractional order, in which the unknown function is under the symbol of fractional derivative. It is due to development of the theory of fractional integro-differential theory and application of those ones in different fields.
The fractional integrals and derivatives fractional integro-differential equations are wide using in modern investigations of theoretical physics, mechanics, and applied mathematics. The fractional calculus is a very powerful tool for describing physical systems, which have a memory and are non-local. Many processes in complex systems have nonlocality and long-time memory. Fractional integral operators and fractional differential operators allows to describe some of this properties. Using of the fractional calculus will be helpful for obtaining of dynamical models, in which integro-differential operators described power long-time memory by time and coordinates, and three-dimensional nonlocality for complex medium and processes.
Differential equations of fractional order appears when we use fractal conception in physics of condensed medium. The transfer, describing by the operator with fractional derivatives at long distance from sources, leads to other behavior of relatively small concentrations as compared with classic diffusion. This fact redefines the existing ideas about safety, based on ideas on exponential velocity of damping. Fractional calculus in the fractal theory and systems with memory have the same importance, as a classic analysis in mechanics of continuous medium.
In last years, the application of fractional derivatives for describing and studying of physical processes of stochastic transfer is very popular too. Many problems of filtration of liquids in fractal (high porous) medium leads to the need to study boundary value problems for partial differential equations in fractional order.
In this paper considered first boundary value problem for stationary equation for mass transfer in super-diffusion conditions and abnormal advection. Then solution of the problem given explicitly. The solution obtained by the Fourier’s method. Also, studied some properties of this solution.
Obtained results will be useful in liquid filtration theory in fractal medium and for modeling of temperature variations in heated bar.
Keywords: equation of fractional order, fractional derivative, Mittag-Leffler function, eigenvalues, eigenfunctions, the Fourier coefficients
Aeronautical and Space-Rocket Engineering
The main objective of Safety Management System (SMS) is to provide a reasonable level of safety risks and operational errors, as well as hold them under the control. To solve this problem it is necessary to promptly identify hazards and assess the severity and frequency (probability) of events that may occur. This article preesents a simulation system of air traffic, that allows to perform safety risks analysis using statistical simulation of the air traffic flow in controlled airspace, operations of air traffic controllers (ATC) as well as the impact of hazards, such as faults/failures of technical systems and errors/violations of ATC and aircraft crews. The air traffic flow submodel simulates flights through the airspace area, which executes various parts of their route — en-route flight, climb after take-off from airport, descent. The most detailed submodel of air traffic controller was developed to simulate the execution of routine tasks of ATC, such as aircraft tracking, messaging with aircraft crews and between controllers, environment analisys, conflict detection and resolution. The submodel of air traffic is able to simulate flights in the airspace of ATC sector. Other submodels of navigation system, ground surveillance system, communication system are comparatively simple, they provide an opportunity of faults and failures simulation. Count of collisions, dangerous proximities and violations of separation minima are calculated during simulation. The model alows to perform the safety risk assessments, and evaluation of minimum time between failures for technical systems. Also, it is possible to obtain different indicators of ATC system, such as ATC workload, mean count of airplanes under control, intensity of air traffic, operation delays and others. On the basis of the model studies of safety of flights in creating the St. Petersburg enlarged airspace center have been perfomed. Three types of hazards were considered: changes in the bounderies of sectors, combining radar data from all sources and air traffic control from a single hall. For each sector some different scenarios were used: with current and perspective airspace structure, with real and increased air traffic flows. Three sectors were considered ULLL/South-East, ULLL/North, ULLL/Petrozavodsk. Studies showed, that the reorganization of airspace does not lead to unacceptable risks.
Keywords: aviation safety, simulation, hazard, risk assessment
Keywords: seminatural modeling, stability, controllability, adaptation, identification
The article is devoted to the design of structures made of composite materials (CM) and contains the problems that arise when designing such structures. It is shown that in all cases of the structure loading, local bulk stress concentrations of stretching-compression (wrinkling) appear in the layers of CM pack in the joint zone of regular part (fixed in composition of CM pack) with the adjacent structure. In this case, the structural strength will mainly depend on the strength of the binder. The dependence of concentration factors is shown. Theoretical formulas for estimation of the joint action of local stress concentrations on the strength of the structure effect do not exist. Stress concentration magnitude in CM layers versus constructive and technological factors, material properties characteristic is shown.
The article presents an empirical formula for the loss of strength in the joint zone in relation to the regular part of the structure estimation. It is shown that actual increase of thickness in the joint zone in comparison with the regular part of the construction depends on the number of fasteners rows. With double-row seam the thickness increases, respectively, by 1,5–3 times, and with triserial — by 1–2 times. It is necessary herewith to take into account the non-uniformity of fasteners rows loading.
The dependence of weight saving by replacing B95 stringer panels with CM structure fr om the volume (area) fraction of joint zones related to the total area of the panel.
The presence of joints reduces possible weight saving of the structure by 35–37%. If the value of the joint zone square fraction is more than 20% of the total CM panel area, implementation of CM by weight criterion loses its meaning.
Optimal structure of CM panels and racks will be the structure, wh ere the strength of the binder fibers corresponds to the strength of bearing layers, which corresponds, for example, to the structure of animal bones.
Keywords: structure, composite material, stress concentration, connection, problems
Methodology of detecting and analyzing rough aircraft landings based on numerical simulation of incident
Modern widely used methodology of estimating damage of an aircraft after rough landing is based on two parameters — overload at the center of gravity and aircraft landing mass. Because of high complexity of landing dynamics such approach in some cases could be very unreliable. The most important in methodology is a key term of making decisions about possibility of further aircraft operation. The need to develop the new criteria of rough landings for both operated and developed aircrafts today is obvious to many aviation experts.
New method of detecting rough landings is presented in current work. It based on flight data from an aircraft such as vehicle orientation, translational and angular velocities, overloads and weight. This information represents the initial conditions of detailed math model of an aircraft interacting with a ground. Aircraft model includes flexible airframe and nonlinear landing gears. Finite-element model of the airframe was built with beams and lumped masses elements. This simple model represents all general inertia and stiffness characteristics and was verified with experimental data obtained from modal test of the full-scale aircraft. The math model is built in widely used preprocessor MSC.Patran. Using programming language it can be built automatically. This feature is very useful for research on wide range of load cases. Landing gears are modeled using solid parts linked with non-linear forces. Whole problem was solved using MSC.Adams solver. The model corresponds to Tu-204SM civil aircraft and carefully verified with experimental data.
A functional relationship between landing loads and landing conditions is planned to obtain as a result of investigation of wide range of landing cases. This relationship allows estimate aircraft state after the rough landing using data from flight recorders without any numerical simulation of landing incident.
Keywords: jet, rough landing, amortization, MSC.Adams
During the engineering design all kinds of self-oscillations should be excluded, including «chord flutter» and ground resonance.
The importance of structural main rotor hub parameterization is determined by helicopter safety during the flight and on the ground.
The article is devoted to the research of impact of available damping over the main rotor stable operating. The flutter calculation was made by means of isolate blade disturbance motion analysis. The equations of flexural-torsional oscillations are contemplated in the stability analysis.
The solution stability of differential equation system with periodic indexes, describing blade oscillations, is considered by means of numerical Floсk technique.
It’s shown, that unsteadyness of main rotor blades, in mode with dominating blade oscillations in plane of highest stiffness («chord flutter»), can’t be excluded only owing to relative first lag-mode frequency of free oscillations, . It’s essential to bring into construction a damper with the required damping value.A type of construction of light helicopter bearingless main rotor (BMR), without in-plane damping and with it, is reviewed in this article. The insufficiency of only structural damping due to exclusion of «chord flutter» instability is also revealed in this article. The analytical model that can be used for the wide range of bearingless rotors during the stability analysis is also proposed. The method of calculation of elastomeric damper parameters is adduced in this article. The formulas that define requirement damper stiffness for relative damping calculation were developed. The linear dimensions are defined using them. The value of damping required for the exclusion of «chord flutter» is shown.
Keywords: main rotor, damper, flutter, differential equations, differential equations, blade oscillations, stiffness, main rotor hub
The analysis of the parameters of small-size unmanned aerial vehicle vertical takeoff-planting increased range. Describes the objectives and tasks of the operation of this unit.
Created unmanned aerial vehicle vertical takeoff-planting aircraft is based on the aerodynamic design of the «flying wing», with integrated four horizontal lift fan of large diameter ranging in ring mines in the thicker portion of the wing. This greatly simplifies the management and load balancing modes, vertical takeoff and landing, as well as modes of complex maneuvers in flight.It also reduces noise and increases the safety during maintenance. Horizontal flight provides pullings crew propeller engine. Lifting force in horizontal flight mode is created with the end portions of the wing profile of the decrease in the relative thickness. Gondola payload and special equipment is located on the rigid suspension below the wing at the center, which provides (low alignment) additional stability in horizontal flight and take-off and landing.To stabilize the longitudinal horizontal flight at the top of the wing at the junction of the large and small parts, there are two vertical keel. Chassis — or four-wheel-type «slide».
The device is controlled via radio with remote control in manual or automatic modes. In automatic mode, the entire flight from takeoff and landing is performed without operator intervention.Flight was made on a previously set route.
In automatic mode implements the following features: automatic take-off, automatic landing, the flight of the programmed route, automatic return to the starting point, the mode of «hovering» at a given point, circled the object of interest in a circle with a given radius.
Ultralight carbon fiber casing, carboxylic and high foams gives high performance characteristics, which is very important for transport and targeted delivery of small loads. The design created by LA can increase the payload and flight range by increasing the wingspan.
Keywords: aircraft with vertical takeoff and landing, unmanned aircraft, flying wing
Rocket and space engineering
The object of this study is the aerospace system that radically reduces the flight time at intercontinental ranges (up to 18000 km.).
The aerospace system is based on a rocket sub-orbit launch. The three-stage orbital launching system consists of a subsonic carrier (like a foreign analog SpaceShipTwo ), hypersonic plane-booster with liquid-propellant engine  and a shuttle with liquid-propellant engine. The launching mass of space-rocket system is 120 tons.
The aim of this work is to design a new generation of aerospace system configuration (Fig. 1) and to estimate the impact of different fuels on the main technical characteristics of space-rocket system (payload mass, overall dimensions of stages, fuel tanks volume etc.).
The research methodology is based on the synthesis and analysis of the design-theoretical, scientific and technical background of TsAGI  in this area including reusable aerospace systems as well as additional design studies using sets of computer programs developed in TsAGI.
Fig. 1 Aerospace system in 2D and 3D.
The configuration design of the future twin-fuselage carrier and three versions of aerospace system with different fuels in the first stage were accomplished in this work. Aerodynamic and flight characteristics of space-rocket and aerospace system as an assembly were determined. It was shown that the considered aerospace system concept permit to reduce the time of intercontinental flights to 80 minutes. The best variant in terms of payload mass is to use the oxy-hydrogen fuel in the first stage of space-rocket system.
Procedure of initial parametric reliability analysis of electropneumatic valves for systems of space rocket complexes
An important scientific and technical problem is the preparation of electropneumatic valves (EPV) for gas supply systems of space and rocket complexes initial reliability analysis method taking into account the production process effect.
The investigation of the present work is concerned with EPV. The subject of investigation is an initial parametric reliability of EPV. The investigation objective is the development of EPV parametric reliability analysis system taking into account the valves production conditions.
At the first point of work the analysis of existing methods of EPV reliability calculation was performed.
At the second point the EPV schematic circuits and functional concept were studied. What is more, deterministic mathematical and digital models of the most widespread EPV designs were worked out.
At the third point the analysis of influence of EPV parameters spread in values on their technical characteristics was carried out. As a result the list of parameters which make the greatest impact has been received.
At the fourth point the investigation was performed, its objective was to determine the type and the parameters of distribution law of values of production deviation of parts sizes, springs hardness and sealants mechanical properties.
At the fifth point an approach to form the digital models of operation of EPV with regard to the production process was developed. In accordance with the accepted approach and using the results obtained previously a series of computer programs was designed.
At the sixth point the method of EPV initial reliability calculation was developed, this method is based on developed mathematical models, obtained research results and accepted assumptions.
The proposed method for evaluating the initial reliability of the EPV has received approval during the process of development of the new-designed pneumatic automation systems.
Keywords: electropneumatic valve, parametric reliability, gradual failure, production process, procedure
Monoscopic stereoimaging performance evaluation models for Earth remote sensing spacecraft subject to on-board systems reliability
Object of investigation: Monoscopic stereoimaging reliability figures and productivity.
Subject of investigation: Monoscopic stereoimaging productivity evaluation for Earth remote sensing spacecraft with allowance for on-board systems reliability and motion control system dynamic characteristics.
Investigation objective: Developing models and algorithms for on-board support system partial failures and target hardware effect on monoscopic stereoimaging productivity simulation modeling
Procedure of work: the paper uses logical-probabilistic approach for complex engineering systems operating capacity analysis; simulation modeling, statistical testing, and statistical analysis methods On the basis of materials on failures statistical data analysis, we suggest a target operation fault time estimation model depending on the observing spacecraft level of reliability. Power gyroscopic system mathematical models of failures development is based on forming stereoimaging kinematic diagram with account for power gyroscopes failures.
Results: On the basis of imaging performance assessment algorithm, an algorithm and mathematical models of on-board control system failure have been developed for monoscopic stereoimaging performance evaluation. Monoscopic stereoimaging performance evaluation technique has been proposed for Earth remote sensing satellite with account for reliability characteristics of on-board support systems and special-purpose electrooptics. This technique is based on simulation modeling of spacecraft special-purpose operation with account for of on-board systems failure.
Practical applications: The results of the studies are used at early design stages of observing spacecraft for target efficiency evaluation with account for on-board systems reliability indices. It possible to evaluate the monoscopic stereoimaging performance with account for on-board systems reliability and movement control system dynamic characteristics.
Resume: Mathematical models of powered gyroscopic system failures, simulation modeling algorithm of powered gyroscopes partial failure impact on monoscopic stereoimaging performance of observing spacecraft and relevant software have been developed. Implementation the software gives possibility to obtain monoscopic stereoimaging performance versus spacecraft reliability characteristics with account for changing of slew angular velocity. Such dependences allow evaluate the monoscopic stereoimaging performance fully depending on the reliability level of observing spacecraft and dynamic characteristics of powered gyroscopic system.
Keywords: spacecraft, monoscopic stereoimaging, powered gyroscopic system, failure
Parameters characterization of pulsatile liquid flow in bioreactor closed microchannel at orbital station
This work aims at main physical parameters characterization of pulsating flow of nourishing liquid in closed micro channels (100 μm height, 500 μm width) of bioreactors for cells cultivation onboard the orbital station
A series of experiments allowing consider pulsating nature of the fluid flow in the channels and determine the speed and flow rate of the liquid delivered to the cells without tracer agents insertion was conducted on a specially designed stand.
According to the data obtained from the pressure sensors integrated into the fluid micro passages, the dependencies of fluid flow rate and speed versus various pressure values (±10 kPa, ±30 kPa, ±50 kPa) and frequencies (: 0.1 Hz, 1 Hz, 2 Hz, 3 Hz) were determined.
Methodology of liquid flow in micro channels characterization, allowing estimate the values of pressure, speed and flow rate of liquid delivered to the cells without insertion of tracer agents was experimentally evaluated.
Dependencies of pulsatile liquid flow parameters versus operating modes of the pump in the microchannel of bioreactor for biological research on orbital station were obtained. Our study shows that increase of operating frequency of pump valves leads to an increase of liquid flow rate and average velocity of nourishing liquid. At the same time, flow velocity peak or maximum instantaneous values for various cycles of the pump operation are equal in amplitudes and do not depend on operation frequency of pump valves.
The obtained experimental dependencies of pressure losses in microchannel segment versus the flow rate in it give the possibility to determine the flow rate in closed microchannel at any operating mode of bioreactor without its integrity violation prior to its proper use.
Keywords: microchannel, flow rate, pressure drop, pulsatile liquid flow
The paper presents the results of designing the small satellite created in the JSC «Academician M.F. Reshetnev «Information Satellite Systems» for Earth observation purposes.
The objective of this scientific work is creation of the Earth remote sensing small satellite, which will fully comply with the world trends of space technology progress and the current SC technical requirements.
This objective is achieved due to creation of the Earth remote sensing small satellite based on the new multipurpose space platform — «NT-100-01». This platform uses the active, triaxial attitude determination and control subsystem, the main loop of which is designed on the basis of star trackers and control drive wheels. Such an engineering solution allows to use the satellites on the «NT-100-01» platform basis to perform tasks of high-accuracy shooting of the Earth surface in different optical and radio ranges, as well as to perform, if necessary, the satellite repointing for shooting of objects that are not covered by the satellite-covered area.
The small satellite could be launched into low circular operational orbit by single launch (including concurrent launch), as well as by tandem launch as part of several small satellites unit.
The Earth remote sensing small satellite of high spatial resolution and multispectral shooting is intended for multiregion remote sensing of the Earth surface for the purpose of:
The information obtained from the small satellite could be used for performance of the following tasks:
Aircraft engines and power generators
Application of fuzzy logic algorithms to control the speed of the power turbine of a gas turbine engine
The article focuses on the issues of enhancing the quality of electronic system for gas turbine engine automated control. It also analyzes power turbine rotation frequency control loop with various electronic regulators, such as linear PD-controller, PD- controller with reduced the proportional gain, fuzzy P-controller with differential compensating element.
During operation of turbine rotation frequency control loop with initial PD-controller the required transient performance quality can not be provided. Achieving the desired speed of the power turbine is accompanied by an overshoot of about four percent 4% and amplitude ripple of 0.2%. Response time can be up to 20 seconds. Reducing the proportional gain provides aperiodic transient, increases stability margin (no overshoot) and static accuracy. However, required performance cannot be achieved. Transient time comes up to 15 seconds. Fuzzy P-controller provides high static accuracy and performance, but the transient is accompanied by overshoot. To decrease this overshoot and provide aperiodic transition process with fuzzy logic controller differentiator with a negative gain is added. Due to its negative gain, differentiator compensates the overshoot. For controller proper operation differentiator operates in a strictly defined range, when the following error of the power turbine speed falls within the limits of ±[0.25%, 2.9]%.
The developed controller increases the system performance up to 6 seconds, and provides an aperiodic transient, as well as high static accuracy of the system.
The analysis showed that non-linear or piecewise controller is the best choice to ensure the required quality for speed control of a power turbine. For example, it can be PD-controller including a fuzzy P-gain and differentiator with limited interval of operation. Operating range of differentiator depends on power turbine speed mismatch errors.
Keywords: gas-turbine engine, power turbine, PD controller, fuzzy logic controller
A numerical method for determining the thermal contact resistance of wavy surfaces is considered. This method is based on the solution of the mechanical problem with the latest achievements of the contact mechanics and the elemental analysis of the heat flow’s passage through analyzed connections which are modeled by superimposing the roughness on the wavy surface.
Described stages of the simulation allow to determine the actual area of the contacting surfaces using software package ANSYS. Deformation is calculated by the known properties of the contacting materials and attached specific load. Later a temperature field is defined by the known geometric model and given values of the heat flow, the thermal conductivity and a temperature of one of the surfaces. Further the temperature field is compared with the temperature distribution of uniform material which characterizes the ideal connection. The value of the thermal contact resistance is defined as the temperature difference between the second boundary of the analyzed real and ideal connections which is divided by the heat flow density. The results of calculations are compared and demonstrate a good coincidence with the known experimental data and the known complex analytical functions. The results of the work are illustrated with drawings of the three-dimensional stress distribution and temperature field near the contact spots. Comparison of the results which are obtained in this work are made in the form of two graphs, which shows the data of experiments and calculations on the analytic dependence. The results open up the possibility to abandon complex formulas which are based on empirical equations.
The results of the research work allow the proposed method to be used widely for finding the temperature difference in the thermal loaded connections of the real constructions.
Keywords: wavy surface, thermal contacting, thermal resistance, model elements
The improving the efficiency of management of technological processes in the manufacture of precision molded compressor blades of turbojet
For creating of modern engines and ensuring their serial production becomes a matter of priority to develop a model of formation of a strategy to improve the efficiency of production on the basis of new technical solutions and improved processes to create products.
Particular attention should be paid to high-volume engine components. The most common items are the gas turbine engine compressor blades. The currently existing in RF technology of production of compressor blades is not unequivocal, the principles of its construction is not structured.
The purpose of this work is to increase the efficiency of technological process of manufacture of compressor blades of turbojets. The authors analyzed the technical process using the tools of quality management, built-up the flowchart of process and identified one bloc that needed to be modified.
Workpiece production is the most resource-intensive stage in the process. It is performed by hot extrusion and hot stamping. The matrix for stamping is a very expensive and responsible element of technical process. Operations on its production are very labor-consuming and include locksmithing work by a worker. To avoid this non automated operation, we take a stamp after locksmithing changes and after receiving on her correct workpieces of blade, and scan it. Stamp for producing blade workpieces was scanned by CMM machine. Based on it the 3D model of stamp has been designed. From 3D model we can create new drawings for production.
The proposed process can be used for improving the technology of producing blades that are already applied in aviation industry, and to ensure the high effectiveness of new blade standard size production.
Keywords: die Tooling, stamping, workpiece of blades, flowchart, quality control
Recently low mass satellites (up to 100 kilograms) are actively developed and created. These devices can be used for remote sensing of the Earth and for other purposes. To maintain the orbit of these satellites and to increase their active lifetime and the share of the payload we should have the appropriate engines to control their orbital motion. As these engines can be used electric propulsion with the power of several tens watts, which are having significantly greater lifetime and specific impulse compared to liquid-propellant rocket engines.
This article presents the results of studies on the development and creating of the laboratory sample of radio-frequency ion thruster (RIT) with a capacity of 20-30 watts. Calculation of the basic operating characteristics of power consumption for the 20, 25 and 30 watts had been done. It was shown that the efficiency of the engine can be achieved up to 32%, with the thrust of the engine up to 0.5 mN. For the three modes of operation of the engine (at different power consumption mentioned above) calculation of basic geometric parameters of the electrodes of the grid system, which allow to achieve calculated characteristics of the engine, was done. Calculation of geometric parameters was performed in the software package IGUN. As input data were specified current density of ion beam and the electron temperature of the plasma in the discharge chamber and the potentials of the electrodes of the grid system of the thruster.
The design of the engine was made. It was given the constructive scheme of the laboratory sample of radio-frequency ion engine that meets the calculated results of the study. Currently the process of manufacturing of thruster’s parts and components is going on. Thus, an inductor, a ceramic discharge chamber and the electrodes of the grid system and electrode holders were made.In the future it is planned to make an experimental test of the sample of radio-frequency ion thruster capacity of 20-30 watts based on facility of the Moscow Aviation Institute in order to confirm the calculated characteristics.
Keywords: High-frequency ion engine, ion-optical system, small spacecraft
Instrument making, metrology, information and measuring equipment and systems
In this paper research results of the weak (<0,5 mT) ELF (0,1-100 Hz) magnetic fields generated near Earth space by original measurement method, by water electric sensors and instrumentation, are given.
The method is based on discovered earlier phenomenon of change of water electric conductivity properties under a magnetic field action. Research of different physical factors influencing on water presents severe experimental difficulties. So at this research stage the most important task is the improvement of apparatus and measurement technique to get measurement repetition and to obtain accurate and reliable experimental data.
The measurements of magnetic field inductance of 0,77 mT and of 6-8 Hz frequencies were carried out in this paper. The greatest influence of magnetic field on electrophysical water features and sensor parameters has been observed for frequencies of 6,5 and 7,5 Hz. These results agree well with ionospheric waves excitation and Schumans resonances.
The present study provides a starting-point for further research.
Thus the developed water electric sensors and instrumentations allow to measure and research weak ELF magnetic fields excited in near-Earth space. The measurement problem of ELF weak magnetic fields caused by ionosphere phenomena and connected with solar activity influence on Earth space is of great interest for both scientific and practical applications. The study of magnetic field influence on water is very important for magnitobiology, water physics, as well as for solar-earth connections and solar activity influence on biosphere and noosphere. From a practical standpoint this problem is very important for determination of ELF wave influence on space radio channels parameters for aerospace information system.
Keywords: information and telecommunication technologies, sensors, electroconductivity, magnetic field
Analysis of design parameters influence on the characteristics of optical microelectromechanical angular velocity transducer
Optical microelectromechanical (MOEM) angular velocity transducer may be constructed on the basis of optical tunneling effect (OTE). Characteristics and measuring range of such a transducer are determined by design parameters of its units. The influence of destabilizing factors on the angular velocity transducer are calculated.
This paper describes the created refined mathematical model of the MOEM angular velocity transducer based on optical tunneling effect that provides high sensitivity with low-rate measurement error and defines conversion function of the refined mathematical model. The described method of determination of optical output power Pout by using refined mathematical model performed to take into account the variability of the initial gap for different contact points of optical radiation on modulated boundary of the prism. Thus, the optical output power is defined as the integral dependence of all points, which are located in the obtained elliptical region by taking into account the variability of the gap d.
The modeling of characteristics of the transducer and the definition of relative errors of the optical output power POUT_ref with refined mathematical model are calculated and compared with result that has been received when used approximate model POUT_app. It is shown that the measuring error decreases when using the refined model instead of approximate model.
The influence of design parameters of the sensitive piezoelectric element (SPE) on the characteristics of the refined mathematical model of angular velocity transducer based on optical tunneling effect is described. To ensure the margin of error (less than 1% on the entire range of measurement) it is needed to use technologies which allow to manufacture SPE with deviation of thickness not more than ± 0,5µm and of length not more than ± 0,25mm.Additional temperature errors of the MOEM angular velocity transducer on the entire operating range of measurement are calculated. It is taken into account the temperature influence on all parameters. Analysis carried out that the impact of temperature in the range of measuring had little influence on the characteristics of the transducer (values of additional temperature error on the borders of the working temperature range are 0.11% (at T = - 500С) and 0.18% (at T = 1500С) at the maximum angular velocity ±4 rad/s). Using two channels of output signals decrease the temperature dependence by 8 times compared with single channel and improve the linearity of the conversion function.
Keywords: transducer, angular velocity, optical tunneling, reflectivity, errors, temperature
Theoretical development of space-born lidar installation based on cw chemical DF-laser onboard for atmospheric monitoring
The first step in the solution of a serious problem of the atmosphere pollution is the study of the nature of its pollution form. Today lidar solves this problem with a high degree of accuracy.
The purpose of this work is the theoretical development of the space based lidar installation main subsystems on the basis of the cw chemical DF-laser (CCDL), operating in pulse-periodic mode.
In the process of lidar installation design, we considered the following: active environment generator (AEG) of CCDL, optical system, photodetector, forming telescope, emission receiving and transmitting channels. We propose master clock—power amplifier structure (MC—PA) as CCDL optical system. DF-CCDL transition to pulse-periodic mode with pulse on-time of 15 ns is performed by clock resonator Q-factor modulation with CdTe electro-optical gate.
As AEG prototype of AEG CCDL AEG Mg-5 developed at NPO «Energomash», enhanced up to the active environment area of 564 cm2, perpendicular to the flux is used. Estimated peak power of emission impulse at the system output was 2,6 MW.
In the course of receiver design, it was suggested to implement the InSb photodetector with effective area of 0.1 m3. The weight of the designed installation with allowance for fuel reserve for operation during 1495 s is 2.76 tons, with occupied volume of 6.49 m3. The weight of the spacecraft with the lidar installation on board equals to 5.73 tons. The carrier rocket Proton-M was used to place the installation into deployment orbit. Evaluation of propane concentration range detected by the developed installation was carried out; and the results are as follows: 472 — 0.21 mg/m3, which exceeds the TLV upper limit more than 1.5 times. The same is for ethane: 434 — 0.036 mg/m3, which exceeds the TLV upper limit more than 1.5 times; methane: 735 — 1.02 mg/m3, which is twice the TLV upper limit. The results show that the developed lidar allows obtaining information even from severely contaminated regions.
Onboard systems for automatic detection of obstacles on a runway are highly demanded nowadays. Such systems reduce the potential hazard for the safety of air travel during the landing and the takeoff stages of the flight. Ground based obstacles detection systems are being tested in the biggest airports. Such systems usually use LIDAR or optic sensors.There is a high demand for a mobile obstacle detection system that could be installed on an aircraft. This paper presents an algorithm for detection of obstacles on a runway based on an iterative minimization of a difference of scale photographic maps of a runway. Scale photographic maps are generated from images captured by an onboard camera.
The paper presents the structure of the proposed algorithm and detailed explanation of its major steps: the generation of a photographic scale map, the creation of a scale map difference image and the estimation of geometrical parameters of an obstacle. The paper also concerns a problem of an automatic estimation of the class of the detected obstacle. It is proposed to create a database of 3D-objects of potential obstacles. The class of the discovered obstacle could be estimated by comparison of its dimensions with dimensions of objects in the database.
The proposed algorithm was tested using image sequences of a runway created using a 3D-model on an airport and a scale model of a runway. The algorithm demonstrated reasonable precision and robustness during experiments.The next stage ofresearch is supposed to be the development of more accurate foreign objects classification algorithm and modification for real-time application.
Keywords: aircrafts, foreign object detection system, safety of the flight, digital image processing, photogrammetry
One of the critical problems of Earth remote sensing is data binding to images when necessity of on-line processing of large bulk of data with due attention to high precision and reliability arises.
Manual binding requires a great number of resources. Thus, a need to design an automated data binding system satisfying imposed requirements becomes relevant.
Data binding assumes imagery comparison, when one image is transformed to match another one. Precise automatic imagery comparison presents a complicated task and has a set of solutions, heavily dependent on the nature of photographed scenes. Creation of universal method seems to be impractical for several reasons. Thus, with allowance for a number of assumptions, we propose a method combing currently available methods.
The first stage of the proposed method consists in search area selection, based on a priori information.
In the course of the second stage, the search area is covered with temporary points.
Very often images of earth sensing contain uninformative temporary areas in the form of forests, fields, water bodies etc. Thus, we need a method allowing obtaining mostly clear cut objects among uninformative areas.
To achieve this goal we suggested implementation of Moravec operator based on calculating the mean value of image pixels values squared differences in different directions. Image fragment with considerable brightness changes gives greater value of Moravec operator.
For search area uniform coverage with temporary points, and multiprocessor systems performance optimization, the search area is split into sectors, and Moravec operator is applied to each sector.
The third stage consists in points positions refinement using areal methods. Prior to it, scale difference and rotation of compared images compensation should be performed.
Supporting points obtained undergo verification, and pairs of points with poor measure of concordance will be rejected. Then compared image is transformed according to selected transformation model, using previously found supporting points.
This work has been realized as part of the software package, built on a client-server architecture. Calculations are made on dedicated servers. The client part is used by operators, to generate jobs and sending them to the server for later execution, as well as performance monitoring, display and editing obtained results.
Keywords: geolocation, remote sensing of the Earth, image transform, informational content, correlation, image processing, image comparision
Nowadays, the rocket and space industry is extremely needed for a reliable test equipment, which is characterized not only by high accuracy, but is also able to work in automatic mode. Test rigs with computer-controlled static inertial characteristics may serve as a proper example. The operating technology of these rigs is designed to minimize the number of manual and transport operations.
Besides the accurate determination of static inertial characteristics — mass and center-of-gravity coordinates, it is possible to significantly increase the quality of spacecraft work process by measuring the dynamical inertial properties. It is especially important for interplanetary spacecraft and deep space stations. Thus, it is necessary to complete the structure of the static balancing test rig by measuring the spacecraft main central moments of inertia and the direction of its main central axes of inertia (the main parameters of the central inertia ellipsoid).
The main purpose of this work is the development of the multipurpose method for measuring the inertia tensor parameters of the spacecraft in its bound coordinate system. The method being developed is based on the existing static balancing test rigs.
The objectives of the work are:
1) To make the choice of the basic method for measuring the spacecraft parameters of the central inertia ellipsoid based on analysis of techniques used in practice.
2) To optimize the process of measuring the parameters of inertia tensor for objects with different ratios of inertial characteristics within the permissible loads on the rig.
It is necessary to carry out a comparative analysis of the current equipment models to choose the optimal base scheme of combined test rig it. Nowadays the development of test rigs is elaborated in many countries. The general trend of modernization is to increase the level of accuracy of measurement and automation of the measurement process. Leading companies in this field are «Space Electronics» (USA), «APCO Technologies» (Switzerland), FSUE «NPO «Tekhnomash» (Russia) and FSUE «TsAGI» (Russia). Significant disadvantages of the various types of equipment are low accuracy, the use of complex engineering solutions (current balance, air bearings) and the lack of technical means to measure all the parameters of the central ellipsoid of inertia without relocation.
It is suggested to use the method of inverted physical pendulum with a stiff fixation as basic for measuring the moments of inertia. The method consists in calculation of the moment of inertia about the axis by the measured values of period of harmonic torsional oscillations made with an elastic system. The value of stiffness coefficient of this system is calibrated. The dissipative forces are acted on a system and causing damping of the oscillatory process during oscillations. These forces include friction forces in rolling bearings, the friction force in the spring material, the frictional force of the air. The friction force makes a significant contribution to the dynamics of oscillations, so there is a problem of its compensation. Supplement the measurement system by the control device capable to create a self-oscillation process can serve as a solution.To ensure the metrological parameters specified by the technical requirements of the test rig it is necessary to maintain the oscillations on strictly defined amplitude for spacecraft with different inertial characteristics.
Keywords: moment of inertia, inertia tensor, balancing, test rig, spacecraft
Radio engineering and communication
The paper presents a new tomography method of remote coherent sources signals processing. This method allows reconstruct 3D coordinates and power of coherent source by the spatial covariance matrix of received signals. This method was patented
Presented method consists in the following. The area under control, knowingly containing coherent signal sources, should be divided into spatial elements of resolution. The size of these elements defines the accuracy of precision of position location definition of the sources. Let us fix the coordinates of elements of resolution, as well as attenuation of radiation coefficients and phase advance, emerging due to spatial signals distribution from each element of resolution to antenna array (AA) elements. This prior information allows reconstruct the covariance matrix of the sources by the components of spatial covariance matrix of received signals.
The covariance matrix of sources is a special matrix, formed as an auto-covariation of the vector, containing the radiation from each spatial element of resolution. The diagonal of this matrix holds the radiation power of each spatial element of resolution. We determine position locations and power of the sources by the source matrix: if the value of a certain diagonal component is close to zero it means the corresponding element of resolution holds no source. And if a source is present in some element of resolution, the power of the source will be equal to the value of corresponding diagonal component.
The principle of the covariance matrix of the sources restoration bases on the new scientific direction — tomography approach in signal processing, which was invented by Professor, doctor of technical Sciences Vitaliy Ivanovich Samoilenko.
In the paper presents computer simulation results. The problem is examined in the plane of the leaner 7-element AA. Simulation results confirm the efficiency of the method.
Keywords: tomography method, coherent sources, covariation matrix, location
Methodology of the designing radars developed at JSC RTI based on the interaction of automation systems engineering design and hardware and software experimental base, and design technology — on the interaction of these components. Accumulated long-term experience has allowed RTI to bring this technology to a high level and successfully use it in the design of several generations of radars.
For these purposes RTI developed a stand of General Designer (SGD), which carried out comprehensive tests of the radar component on the stages from the mathematical model to the final production model.
The main task of the SGD is to obtain reliable data on compliance with the current settings of the developed radar component specified functional-parametric matrix. These data are needed to calculate the availability factor on the basis of which the evaluation of the risk of radar is occurred.
Combining tests of virtual and real objects, on the one hand, offers additional opportunities, and on the other — poses new, previously not decide tasks such as:
· Development of an algorithm for converting the measured component radar parameters to availability factors.
· Development of methodology for adaptive data processing of testing radar components.
The calculation of the statistical characteristics of availability factors is proposed to put the labor input, i.e. the effort required to create modules, because labor input is the most convenient for the formalization of the unit. Labor input is complex index, which are objectively related to the budget, can be represented as a function of the qualifications and competence of staff, and at the same time it is convenient to plan and evaluate, and thus receive verified assessment.
Since information on the execution of projects is stored for each radar component, it provides source data for plotting the availability factor of each component depending on time. It is necessary to consider not only the planned labor input across life cycle, but also the values of the initial estimates of effort invested before starting work.
Thus, the evaluation of the effectiveness of the process of creating radar based on a comprehensive risk index, calculated according to the real information of labor input, enables the transition from deterministic valuation of the design process to stochastic planning and resource management that impact on quality indicators of the processes of creation. The high accuracy of the estimates of the current risk of the creation process of radar is achieved through the data about the realized radar component parameters promptly obtained from the stand of General Designer.
Keywords: radar station, stand of general designer, availability factor, risk, product lifecycle
Modern manufacturing of radio-electronic equipment for flying vehicles requires implementation of cost intensive technological installations of high complexity, specialized premises and skilled specialists. Introduction of state-of-the-art innovative technologies and launching of new production facilities means a group of actions including acquisition, launching, development and organization of operation of complex technologies. Under severe conditions of competition, this process should meet a whole number of factors, which is impossible without application mathematical methods of optimization and software tools.
This work aims at developing of mathematical and software tools to solve the problem of providing enterprises with innovative technologies with regard for technological and economic criterions limitations. In consequence of carried out study we obtain mathematical model that presents target optimal selection in the form of mathematical programming problem. The special feature of the problem is a large number of factors affecting the optimal solution. Moreover, each of the sel ected factors can be transferred to either criterion or limitations. This is where the requirements to mathematical model, algorithms and methods of their software processing come fr om.
The input data of this developed software complex include the structure of an innovative technological process, parameters of production, technological equipment and its installation and operating requirements.
According to the proposed conception of modeling we developed algorithms and programs adaptable to specific productions and complexes of technological equipment, which makes this software complex a universal tool for the set problem.
Keywords: technological process, software package, equipment, quality criterion, limitation, database
The radio connection broadband system of the increased speed in the process of transmitting the information
It has been worked out the approach for the synthesis radio system with high demands to the process of high demands to the process of transmitting the information. This approach is based on the analysis and the application of the more energy efficient designs of a signal. That means using of multi-line constructions of the radio system with the orthogonal code devision of channels into 2 types: non-linear code sequences and multilevel quadrature amplitude-inverse modulation of the signals.
Each channel consists of 2 quadrature channels. The code sequence P1 is used in the inphase channel for transmitting m-symbols of binary information. And the code sequence P2 is used in the quadrature channel for transmitting the second combination of m-symbols of binary information.
Moreover, P1 is orthogond to P2. The high-order digit of m-digit code combination specifies the kind of the sequences P1 and P2. The rest of the m-1 information categories define a discrete value of the amplitude sequence.
In its turn, in each quadrature channel of the receiver there is a convolution of the sequences P1 and P2. Then the sign of the response signal detected is being determined in the demodulator. Then there is a determination of the number of the amplitude interval in each quadrature channel (m-1). This number will correspond to the information category in which the response amplitude of a received signal is. That means, there is a simultaneous assessment of 2m binary units of accepted information in each channel of a receiver.
To determine the values of noise resistance characteristics that’s enough to estimate it in one of the quadrature channel. The lower boundary interval’s value and their absolute value must ensure the selection of the amplitude signals with specified probability of false admission. The size of the intervals has different value, as the resulting probability of the symbol’s false admission depends on reliability of determining the sign and chosen interval amplitude signal’s number.
Dispite the fact that the sequence provides the necessary Walsh correlation characteristics of the ensemble it is extremely limited, which is of significant disadvantage.
It is proposed to the developed modulation type, which was named m-QAIM — multiposition quadrature amplitude-inverse modulation, using code division radio using sequences based on nonlinear full code ring (NFCR).
The article also shows a diagram of a radio transmission device that was developed based on the algorithm proposed SCC using wideband signal.
Thus, the practical realization of the experiment allowed the opportunity to show the efficiency of frequency and power resources in the radio channel.
Keywords: signal-code construction, amplitude-modulation inverse, spectral and energy efficiency, noise immunity, secretiveness, pseudorandom sequence, the orthogonal signals
Analysis of the efficiency of data transmission in a communication network group of unmanned aerial vehicles
Currently, for many tasks it is proposed to use a group (Swarm) of unmanned aerial vehicles (UAV) [1,2,3]. The grouping efficiency is greatly improved when using a communication network, the nodes of which are aircraft included in the grouping.
The movement of the UAV relative to each other causes in the General case, the change of their relative position, resulting in the structure of the network also changes. This leads to the need for each node to periodically update information about the current network configuration.
The basis for the construction of the route is the connectivity matrix of the network, which contains information about the characteristics of the communication channels between the adjacent (i.e., having a direct channel of communication) nodes.
Update the adjacency matrix requires additional exchanges of information between nodes. Because the speed of information transmission is limited, the update of the matrix will be performed for the final time.
The work deals with the problem of estimating the time required to update the adjacency matrices using different algorithms access.
Considered two mechanisms for network access during the upgrade process matrix — cyclic access and random access.
A comparative analysis of access methods showed that in the absence of distortion (or in the case of a small amount of distortion) cyclic access provides higher efficiency compared with random access.
Random access is useful when a relatively high probability of data corruption (of the order of 0.1 and above), a large number of nodes (more than 40) and low network connectivity.
Keywords: unmanned aerial vehicles, data network, random access, cyclic access, routing, network adjacency matrix
Informatics, computation engineering and management
Mathematical support and software
Logical set of control actions to be uploaded on-board a spacecraft to implement a singular control task is called a management procedure.
Problem-oriented languages allow define a management procedure as a script and run it during communication sessions with a spacecraft in automated mode for an unlimited number of times.
All control languages support execution of the following tasks: instruction issue to the spacecraft, setting proper time delays, different conditional tests, and several other operations, such as printing a message to an operator. Recommended functional tasks that should be supported by any control language are described in the following documents: Standard ECSS-E-ST-70-32C: Test and Operations Procedure Language (PLUTO); OMG SOLM specification.
Examples of existing control languages are Python, PLUTO, CSL, JOTR, STOL, TAO, CSTOL, CCL, JAS, ICL, Btscript, Cecil, CIL, TOPE/tcl, UCL, Elisa, PIL, etc.
As for control languages, there are no general tendencies: control languages can be general- and special-purpose, object-oriented and procedural, control scripts can be implemented sequentially and simultaneously, on the basis of priority, scripts can be run upon operator command and automatically, after reaching preset time and conditions.
The great majority of existing control languages aroused the problem of portability, when already designed and tested set of control procedures can not be used to control the spacecraft after control handover from one control center to another, without installing new control software and learning both new control software and control language. As a solution to the problem described, the new software was developed allowing translate control procedure texts from one control language to the other.
Keywords: spacecraft control, spacecraft control languages
Computing machinery, complexes and computer networks
In the board network of aerial vehicles router is a central device that provides interaction with the flight crew, ground crew, board and ground networks. Its main task is to ensure the connection of internetwork and exit to the external network for the crew and passengers, playing the role of a gateway. The default gateway is usually the interface of router. Consequently, the default gateway fault will result in stopping of normal work of network. For the achievement of high-level availability of default gateway redundancy protocols are used. These protocols must provide fault-tolerant connection nodes of intranet with a default gateway and, accordingly, to provide a reliable exit in an external network. An important task is to test and analyze the functioning of the protocol. In this paper, HSRP protocol is examined, because it was the basis for development of other first-hop redundancy protocols such as VRRP, CARP.
HSRP (Hot Standby Router Protocol) — the main task and purpose of this protocol is the achievement of high-level availability and fault tolerance of default gateway. In this paper, the fault injection technique approach is proposed for the analysis of protocol functioning. The basis of this approach is the imitation of an additional router in HSRP group, for the realization of different scenarios of faults. Therefore, faults are injected in HSRP group and protocol’s behavior is analyzed under their influence. Possible refuses in the system and methods of their injection are considered, the experimental analysis of this methodology and protocol is realized under influence of failures and faults.
As a result of the done work is noted, that this methodology meets the requirements, namely: does not depend on the operating system, does not change settings and parameters of the system, does not depend on the chosen topology, amount of routers and HSRP groups.
Keywords: fault tolerance, fault injection, protocol HSRP