Methods and tutorials
The article is devoted to the problems of translation of culture-loaded lexical units of American English included in the Aviation Group. Translation is a culturological phenomenon and a means of cross-cultural communication. The problem of interaction between language and culture is very important for modern linguistics. Language is a particular system of words used by a people or nation. Culture consists of the ideas, customs, and art that are produced or shared by a particular society. The term «culture» embraces the entire way of life of members of a community insofar as it is conditioned by that membership. Cultures are chiefly transmitted through languages.
The aims of this research are: to analyze American realia of air transportation system; to single out aviation culture-specific vocabulary; to investigate the ways of translation of these lexical units into Russian. The importance of air transportation for the USA is connected with geography of the country, with its vast territory. When the airplane became a major factor in mass transportation the term "the second great American revolution in transportation"appeared.
Particular attention is given to the classification of the culture-loaded lexical units. Most widely used translation techniques of translation of aviation realia are compared: transcription, transliteration, calque, descriptive translation. The paper offers a linguistic-cultural description of the words with no direct equivalents in other languages.
We must conclude that analysis of linguistic and cultural problems of translation of culture-loaded words in the air transportation group in American English helps to complete the picture of American culture for the Russian students or readers of English and to explain the meaning and connotations of lexical units.
Keywords: culture-loaded words, language and culture, classification of American culture-loaded lexical units, translation techniques
The article is devoted to the problem of using elements of culture-oriented linguistics in foreign language teaching. The investigation is based on the competence approach. In the course of language learning the students will need to acquire sociolinguistic competence. Sociolinguistic competence is concerned with the knowledge and skills required to deal with the social dimension of language use. Language is a sociocultural phenomenon, a particular system of words used by the people of a particular country to communicate with each other. Communication depends on the congruence of the models of the world and of language which have been internalised by the persons taking part. Of considerable importance to the learner of a particular language is factual knowledge concerning the country or countries in which the language is spoken, such as its major historical, cultural, geographical, environmental, economic, political features (realia), etc. It is the aim of language and culture dictionaries to ‘complete the picture’ for the readers of foreign languages or Russian students, whenever the theme of the matter in question. The overall intention of this kind of Anglo-Russian dictionaries is to reflect modern English to give all the entries a full sense of historicity or contemporaneity. Language and culture dictionaries indicate the special connotation of the given term. The majority of entries would contain an explanation of its significance to Englishmen, notably in cases where this is not apparent from the translation the term itself.
Keywords: culture-oriented linguistics, language and culture dictionary, language and culture, sociolinguistic competence, background knowledge
Mathematics. Physics. Mechanics
In the given work the interval explosion method, which was created by the author, for the solution of the problem of determination of optimum program control of the discrete and continuous dynamic systems is considered (the problems about spacecraft orientation and stabilization and «smooth landing» are solved as the example).
In the modern mathematics a great attention is given to a solution of problems of global optimization and synthesis of optimum control of dynamic system. These problems arise during designing of designs of planes, helicopters, spacecrafts when arises the necessity of optimization of characteristic parameters and of creation of control systems.
Existing numerical methods use various approaches, but their use is connected with various difficulties: the big computing loadings, requirements to problem statement, difficulties in reaching of convergence. Thus, working out of new methods of the optimization, which combine the newest mathematic approaches, is the extremely important.
Besides, it is necessary to notice that it is the extremely important to use and develop heuristic methods. Despite the lack of its strict substantiation, these methods give an acceptable solution of a problem in the majority of almost significant cases. Heuristic algorithms do not guarantee finding the solution and can give an incorrect solution in certain cases. However an essential advantage of such algorithms is their lowest computing complexity that allows to apply them to a solution of problems of the raised difficulty (for example, the problems belonging to NP class). In aggregate with key singularities of the interval analysis (handling of ranges instead of isolated points, low insistence to problem statement) working out of heuristic interval algorithms is the extremely perspective direction.
The main feature of the developed method is combination of interval analysis and explosion heuristics. Method has two search procedures: global and clarifying. This helps to find areas where the global minima can be situated and then to locate its position.
In the given work the algorithm and the software of the interval explosion method for a solution of a problem of determination of optimum programmed control by the discrete and continuous determined dynamic systems were created, applied examples on which efficiency of the developed method is shown were solved. Besides, some recommendations about possible improvements of the created method and its further development were made.
Keywords: interval analysis, global optimization, heuristic algorithm, explosion method, optimal control, dynamic system
An aerospace systems design is based on the optimization problems solving. This design phase is very important, because it allows to find the best combination of characteristic parameter values, that make using of aircraft more effective. For this reason, selection of an efficient optimization method is very important.
This paper considers four bioinspired global optimization methods that are stochastic search optimization technique. Bioinspired methods belong to the group of metaheuristic methods that mimic the natural biological processes and the social behavior of some animal and plant species. These methods become more and more popular, because they allow to find the solution of optimization problems, for which searching optimum solutions with traditional mathematical techniques are ineffective.
Cuckoo search (CS) and Weed Colonization (WC) are evolutionary-based methods. The both methods are inspired by the idea of a new population generation. It means that some of the individuals (possible solutions) with the worst fitness are removed and replaced by the better solutions as a result of natural selection process.
Shuffled Frog Leaping Algorithm (SFLA) and Glowworm Swarm Optimization (GSO) are methods of «swarm» intelligence. The agents of «swarm» intelligence system interact with each other and exchange information in population. Shuffled frog leaping algorithm based on observation of the frogs in population when they search for food.
The main advantage of presented bioinspired methods is solving multiextremal optimization problems with a large number of variables. They do not guarantee convergence to the global optimum, but they allow to obtain a good solution within a reasonable period of time from a practical point of view. These reasons make the applying of bioinspired global optimization methods perspective for solving the complex optimization problems in the aerospace system design process.
Keywords: optimization, global extremum, population, fitness, objective function, bioinspired methods
High-pressure cylinders consisting of an inner hermetic metallic enclosure (liner) and an outer force composite shell from carbon-filled plastic are widely used in space engineering. We suggest a numerical-analytical method of calculating the cylindrical part of a metal-composite pressure cylinder. The method takes into consideration non-linear deformation curve of the liner and structure in homogeneity of the linearly elastic composite shell. Solution of the problem in this formulation is based on the method of successive loading and on the model of an ideal elastoplastic liner at each loading step. Multilayer composite shell is considered to be orthotropic with longitudinal, circumferential and shear-generalized rigidity. Experimental deformation curve of the liner is replaced by specially built analytic approximating polynomial function; this makes it possible to automate calculations.
Algorithm of the metal-composite cylinder calculation in cludes two schemes. According to the first scheme, the composite shell and the liner are madelinearly elastic, and from it we search out the pressure which value corresponds to the limit of proportionality of the liner material. In the second scheme, the composite shell is linearly elastic, and plastic deformations occur in the liner. The second scheme is applied at each loading step of the cylinder; thereto the liner deformation diagram is represented in a step function, ordinates of which are taken from the analytically derived deformation curve, and the length of «the stepping yield plateau» (by strains) is determined by the increment of pressure.
This internal pressure calculation algorithm for a metal-composite cylinder is implemented as a program in MatLAB. The numerical investigations have shown that the accuracy of the results increases with then umber of loading steps. In the article we gave a computation example of the metal-composite pressure cylinder consisting of the liner from the alloy AMg-6 and the carbon fiber shell with spiral and annular layers. We established that 15 steps of loading were enough to achieve sufficient accuracy for practical problems. The longitudinal and circumferential stress and strain in the liner reduced, and had horizontal asymptotes. The program developed for determining the stress-strain state of metal-composite pressure cylinders can be effectively used for designing calculations.
Keywords: metal-composite pressure cylinder, analysis, calculation, mode of deformation, liner, non-linear deformation curve
The prediction of a cantilever flutter for a FV requires a rather precise evaluation of natural torsional and bending frequencies for the fin, which is installed on a FV. However, test data concerning the natural frequencies is not available at the early design stages, which require the creation of the design-production documentation for the fin. So it is necessary to do the appropriate calculations for evaluation of the natural frequencies during these stages.
A finite element (FE) software suite was used to conduct the evaluation of the natural torsional frequency of a fin, which is attached to the frame of a FV via control linkage. At that the modeling required the usage of the solid FE models of the links (levers, rods) of the control system linkage that are conjoined in the lugs with the help of the multipoint constraints (MPCs) and the frame, on which the actuator is fixed. The fin was modeled as a rigid solid body. This analysis allowed to find the upper bound of fin torsional stiffness at early design stages.
The implemented analysis has demonstrated the possibility of evaluation of the natural frequencies of the fin at early design stages. The FE software was employed during the analysis for building the detailed FE model with the usage of solid FE. It was necessary to reduce the computing time due to the need for examination of multiple versions of the structure of the control system linkage at the early design stages. Thus it was deemed rational to use superelements during the conducted evaluation. Such superelements allow to reduce the number of the degrees of freedom in the model. To do this it is possible to use the Craig-Bampton method, which is implemented in some commercial software, or other methods, such as the method of component synthesis for dynamic systems. The latter allows to take into account the required number of oscillation components of the analyzed structure with controllable accuracy during the calculations.
Keywords: stabilizer own frequency, flutter, fluctuations
Estimation and minimization of influence of supporting devices on the aerodynamic characteristics of various bodies during the wind tunnel tests has always attracted considerable attention. The three-dimensional interference of a model and supports is quite complex. It depends on the type of the supporting devices, the character of the flow around the bodies, the angle of attack and the yaw angle. The influence of the suspension system causes the emergence of the systematic measurement errors. Corrections for this influence are especially important for well-streamlined wind-tunnel models (axisymmetric bodies, isolated fuselages of airplanes and modern helicopters.)
Systematic experimental investigations were carried out in the wind tunnel of KNRTU-KAI in order to determine the influence of various supporting devices on the aerodynamic characteristics of axisymmetric bodies with different aspect ratios and helicopter fuselage models.
The supports drag was minimized with the help of a single-panel suspension system, which was designed at the Aerodynamics department of MAI. This approach allowed to identify the influence of various suspension devices (bottom struts and side support stings) on the integral aerodynamic characteristics of various models. It also helped to estimate the nature (cause) and magnitude of the required corrections.
Keywords: estimation and minimization of the influence of the supporting devices, integral aerodynamic characteristics of various bodies, wind tunnel, types of supporting devices, axisymmetric bodies, wind tunnel model of isolated helicopter fuselage
In article questions of development and creation of trial installation of formation of press packets of brake disks of aviation wheels from carbon — carbonic composition materials are considered. Operating experience of installations existing in the aviation industry revealed a number of shortcomings: non-uniformity of fibrous structure of a press packet, bad decomposition of carbon fiber, non-uniformity of submission of pitch, big duration of process of formation, high percent of spoilage, etc. New installation which allows to change essentially the diagram of submission and mixing of components of a press packet was developed for elimination of these shortcomings. Submission of carbon fiber of the guaranteed sizes directly from a zone is thus carried out are sharp also submission of carbon pitch directly from a grind zone in a zone of mixing of components. It allowed to provide stability of executed process, considerably to reduce overall dimensions of installation, to resolve environmental friendliness issues in a working zone. For support of process carbon fibers are sharp was essentially new installation is developed and implemented are sharp which feature is stability of support of the required length of a fiber, its rather low cost, and also possibility of fast readjustment at the required length of cut-off fibers.
Improved under requirements of technological process existing installation for grind of pitch allows creation of granules of pitch of the necessary sizes in case of support, in case of need, to possibility of readjustment on other sizes. Pitch submission directly in a zone of mixing allows to reduce considerably dust formation in case of grind and to exclude «stick together» of particles of pitch among themselves. The developed and implemented aggregates of installation allow to realize fast readjustment on different brands of applied materials that does developed installations of the universal.
The main features of the developed installation and its components are given in article. Also technological process of creation of a compound of materials of necessary quality is considered.
The analysis of existing technological processes of creation of press packets of brake disks and installations for their execution shows that the developed and implemented installation corresponds to world level of the industry.
Keywords: composition materials, brake disks, carbon fiber, coal-tar pitch
The paper reviews the key problems, which arise during the development of a flight control actuator for an advanced agile aircraft. These problems are related to the creation of the requirements for the dynamics and main parameters of the control actuator, which are justified from the engineering point of view. The example of a flight control actuator design illustrates the main methodological approaches to the selection of the values of its control loop main parameters for the advanced agile aircraft with aerodynamically unstable configuration. The values are selected in such a way as to provide the required dynamics of the «aircraft — flight control system — flight control actuator» closed-loop system.
The paper suggests a methodological approach to the creation of justified requirements, which are represented as regions of acceptable values of the amplitude-phase-frequency response characteristic of a horizontal tail control actuator depending on the input signal amplitude. These requirements ensure the complete elimination of the self-oscillating modes in the «aircraft — flight control system — flight control actuator» closed-loop system. In addition the paper proposes a method of determining the basic values of the actuator control loop parameters, which ensure the required actuator dynamics in the whole region of input signal computation. It is shown that the required actuator dynamics can only be attained via the implementation of a comprehensive approach. Such approach should include the selection of a rational functional diagram of the actuator with the use of concept of direct control of flow control valves. It should also encompass the design and manufacturing methods, which would provide the required linearity of the response rate performance of the servo actuator and hydraulic motor of the flight control actuator. Another important part of the method would be the use of digital controllers, which ensure the required stability of the actuator technical performance during the exposure to the destabilizing factors and in the presence of functional failures.
Keywords: agile aircraft, aerodynamically unstable configuration, fly-by-wire control system (FBW), amplitude-phase-frequency response characteristic, electro-hydraulic flight control actuator, servo actuator
The functioning prediction problem solving given the likely off-normal situations is of particular importancein aLife — Support Systemdesign intendedfor interplanetaryspacecraft crews.Oneof the possible approachesto its solution, based on an analysis of perspective regenerative air revitalization system is considered in this paper.The carbon dioxidereduction system designed to removecarbon dioxide from the gaseousenvironmentinhabitedmodulus,its concentration andsubsequent processingbyhydrogenation reactionto gaseoussubstances:methaneand water vapor is selected as an object ofprediction. The proposed approachis based on the simulation modelcreating designed forthe analysis of functioning modesundernormal operationandin the case ofpossibleoff —normal situations. The structure ofthe simulation model, the functionof its individualcomponentsand software implementation are defined andalsothe results of preliminarycomputational experiments are presented.
The proposedapproach to regenerative air revitalization systempredictionfunctioningas a complex system,whichconsists ofinterconnectedtechnological structureunits,operating indifferent timemodesandinteractingwith other systems andthe environment,allowsdeveloping a toolto solve differentdesign problems.
Directionsfor further workare:
1. A verification ofdeveloped simulation modelsbased on the resultsof experimental studiesof individual units.
2. A supplementsimulation modelof reliabilityevaluation procedures.
3. A conductingcomputational experimentsona simulation modeltoestimatethe likelyimpactof failures andoff — normal situationson thedesign parameters of thesystem and create thetechnical condition monitoringof the subsystems andidentifyfailuresin the regenerative air revitalization system technological structure.
Keywords: manned spaceflight, regenerative air revitalization system, carbon dioxidereduction system, prediction of functioning, simulation model
Development results in research on super-heavy rockets in United States, Russia, ESA and China show that promising projects of super-heavy rocketsare constructively implemented based on the schemes of «Energia» and reusable space transportation system «Space Shuttle». The main purpose of the NASAAgency is the Mars mission planned for 2030. Expedition to the Mars demands several launches of new super-heavy rockets, so NASA has focused on the development of «SLS» (Space Launch System) and has displaced creation oflight and middle class rockets to the private companies.
Analysis of global trends in the development ofsuper-heavy class launch vehicles goes in two directions:
1) There are carriers based on the experience of development of «Energia — Buran» and «Space Shuttle». This experience involves the use of solid and liquid boosters and oxygen-hydrogen central unit.
Creation oflaunch vehicle with capacity from 80-85 tons to 200 tons achieved by increase in number of side blocks and Central Bank filling increase.
The high cost of start that may not be acceptable for flight to the Moon.
(~ $ 500 million)
2) There are varieties of carriers with cheaper and safer engines, which allow to reduce the launch cost with keeping security and energy characteristics. For example, the company «SpaceX» has designed rocket with capacities from 53 to 140 tons. Similar options are being considered in Russia. These variants have tendency for the insertion lower coast.
Keywords: super-heavy, SLS, SpaceX, NASA, analysis of global trends
The aim of this work is to find the optimal date of getting a spacecraft (SC) to the libration point L1 of the «Earth — Moon» system with the influence of the second zonal harmonic of the Earth and the perturbing acceleration of the Sun. A ballistic flight happens with two inclusions of the chemical rocket engine. We assume that the criterion of the optimization is the minimum value of the total pulse of the velocity, which is necessary for the flight with a low near-earth orbit to the lunar libration point L1. Ephemerides of the Moon and the Sun are taken from the planetarium DE-403 of the production JPL.
A numerical solution is found for an every date under consideration. We examine a SC movement in the geocentric equatorial coordinate system. A SC movement is described by the differential equation system, which is a special case of the limited three or more body problem. We have got the numerical values by the numerical integration of Runge-Kutta method during the date of leaving the base orbit and the date of getting to the libration point. For the first approach the vector of the initial values (coordinates of the starting point and the velocity components of the spacecraft in the geocentric equatorial coordinate system) is determined by the Homanov’s condition of the flight. The solution of the boundary value and the optimization problem is described in the article. This solution gives us the direct hit of the spacecraft to the libration point. The optimization problem presents the optimal time of the flight for each date of getting into the libration point.
We analyzed the Sun’s position effect on the power of the flight. The choice the regarding period is based on an analysis of the Sun and the Moon.
Results of this work are
· the selection of the optimal date of getting into the libration point L1 of the «Earth — Moon» system;
· the values of the optimal time of the flight;
· the values of the longitude of ascending node of the orbit base;
· the values of the first, the second and the total impulse of the velocity;
· the coordinates of the starting point in the geocentric equatorial coordinate system.
These results can be used for the space project’s development for using the lunar libration point L1.
The comparative analysis of the numerical values of the total impulse of the velocity with and without the influence of the Sun lets us show the importance of the selection of the date. The choice of the optimal date allows us to reduce the total impulse of the velocity for about 4 m/s.
Keywords: mathematical modeling ballistics analysis, Runge-Kutta method, libration point, L1, Earth – Moon
Aerospace propulsion engineering
When protecting the combustion chamber walls liquid rocket engine of small thrust using the internal film cooling the boundary layer is formed between the core flow and the wall as a result of turbulent mixing. Temperature of gases in the boundary layer is lower than the temperature of the main flow and the mixture ratio of components in it is variably along the combustion chamber. For the calculation of the thermal state of the engine combustion chamber and nozzle (in particular, for the calculation of convective heat flow) we need to know the mixture ratio along the walls of the combustion chamber.
The phenomenon of turbulent mixing of gas flows in relation to the working process in rocket engine is studied not enough.
One of the main difficulties of calculation the turbulent mixing of gases is the lack of information on values of the turbulence in the rocket engine combustion chamber.
However, to carry out rough calculation of gas-phase mixing is possible.
In this paper, the results of calculations the ratio of the fuel components by one-dimensional engineering techniques [1, 2, 3, 4, 5] and the results of three-dimensional modeling in ANSYS CFB are presented
The object of study is liquid rocket engine with thrust 200 N, operating on eco-friendly components CH4+O2.
Analysis of the results showed that, with appropriate adjustment, methods of calculation  and  are in good agreement with three-dimensional modeling.
Keywords: liquid rocket engine of small thrust, film cooling, the mixture ratio of fuel components
Spacecraft propulsion and electrical power systems (PEPS) electronic databank (EDB) is being designed. It includes performance onboard propulsion systems (PS) and electrical power (EPS) system as well as the information on PEPS subsystems in the structure of f multipurpose spacecraft. EDB includes some standard and prospective spacecraft PS and EPS which is needed for Russian astronautics tasks. Availability of such EDB will allow to estimate in a complex the state of scientific and technical development in this area at present and in the long term. It also will facilitate for onboard PS and EPS and spacecraft developers to search demanded subsystem during the design and other works. EDB is intended for the experimental design bureau and the scientific research institutes which are engaged in designing and development of spacecraft and onboard PS and EPS.
PS and EPS subsystem performance included in EDB are the prime power sources, energy storage systems, power management and distribution, spacecraft thrusters and also information about PEPS subsystems in various spacecraft structures. Structurally EDB consists of two sections: power supply spacecraft systems and spacecraft thrusters.
EDB has to contain the data on spacecraft PS and EPS performance necessary for developers to solve the current and prospective problems of the Russian astronautics. In this connection within this work the review of spacecraft standard and prospective spacecraft PS and EPS are carried out. The most demanded of them for the EDB structure formation and its further updating planning are defined. The demanded PS and EPS subsystems imply as the PS and EPS subsystems which are commonly made, and from those under development — the most suitable for the solution of future prospective Russian astronautics problems.
EDB includes PS and EPS which can be used in spacecraft, space stations and in the transport spaceships. Prospective tasks imply providing prospective spacecraft meeting the increased requirements for PS and EPS power, e.g. transport service of lunar mission, Mars expedition spacecraft, orbital transfer vehicle.
Keywords: electronic databank, spacecraft, power supply, electrical power system, propulsion system, propulsion and electrical power system
A thruster cluster (thruster module) consists of eight thruster units, each of which includes a 35 kW radio-frequency (RF) ion thruster with the cathode-neutralizer, RF generator, gas-distribution unit (GDU), and power processing unit (PPU).
The thruster module has a three-level concentric structure. The levels are interconnected by a frame system. PPU and flanges for mounting thrusters and cathode-neutralizers with discharge-initiation units are located at the first level. The GDUs for thrusters and neutralizers are located at the second level. The third level contains elements used to fix thruster module to the spacecraft structure.
Each thruster casing is divided into several sections with different radiative properties, allowing directing heat flows from the thruster module components.
Static thermal analysis was conducted by the finite-element method using the software package ANSYS. For constructing the finite-element model and making calculations, the software package Workbench was used. The computational model is based on the developed geometric model of thruster cluster and the required boundary conditions. While developing the finite-element models of the thruster and thruster module parts, there was used a mesh generator ICEM CFD integrated into the platform Workbench. The temperature distribution fields were defined by calculation for each element of the thruster cluster.
Keywords: radio-frequency ion thruster, thruster module, thermal calculation, temperature distribution fie
Mathematical modeling of LRE by thorough theoretical analysis of the developed design and the processes in units and the engine is intended to identify the characteristic features of their functioning and to choose the optimal static and dynamic characteristics of the components and assemblies of the developed engine to perform requirements to it.
In this paper we present the results of the development of a nonlinear mathematical model of 11D58MF liquid rocket engine, developed by RSC "Energia" for use in RB DM type. A mathematical model allows to simulate the conditions of the engine full thrust regime, to carry out energy balancing the engine in a conditions of the deviations of static characteristics of pipelines and all its components (pumps, turbines, combustion chamber (CC), a gas generator ( GG ), throttles, washers, etc.) and to provide the extensive research related to: changing the schema of engine, with abnormal and emergency situations, with the engine operation in conjunction with test units or missile systems, etc. The model also allows you to explore new design solutions for the engine modernization and increasing its reliability.
Keywords: liquid rocket engine, energy balance, thermodynamic performance, non ideal chemical reaction
To analyze the effect of low Reynolds Numbers on losses in a low pressure turbine, the experimental study of gas-dynamic characteristics of two-dimensional cascades for three turbines was performed at low Reynolds Numbers at CIAM’s U300S test bench.
The cascades have similar design and consist of 6 airfoils. Cascade 1 has profiles with loads applied to the mid-portion, Cascade 2 has profiles with loads applied forward and Cascade 3 has profiles with loads applied rearward. All cascades have identical relative pitch and chord and identical flow entry angles b1к and effective flow exit angles b2эф. Reynolds Number was changed as by adjusting total inlet pressure and varying corrected speed at the cascade exit l2is. Turbulizing screens were used in the experimental study.
The study shows the following:
- with the lower turbulence level atthe cascade inlet (Tu = 2%) the level oflosses inCascades 1and 3are nearly the same, while losses inCascade 2are in1.5 time lower;
- with the mean turbulence level at the cascade inlet (Tu = 5%) Cascades 1and 2 have equal level of losses (The difference is less than 1%)
- with the high turbulence level at the cascade inlet (Tu = 12%) Cascade 2 has distinct advantage over Cascade 1 under operation conditions l2is.
To verify the experimental data a numerical simulation of Cascade 1 and Cascade 2 was performed at the inlet turbulence of 5%. The following conclusions can be made therefrom:
- numerical simulation based on RANS transient models makes it possible to define approximate place of flow separation but does not allow evaluating the losses increase when the Reynolds Number is becoming lower.
- numerical simulation based on RANS full turbulence models (k-e, k-w, SST, etc.) for simulating separation-induced flows at low Reynolds Numbers makes no sense because such models do not reflect a physically well-understood flow phenomenon, and the high level of losses in these models is achieved through high eddy viscosity of nonphysical nature.
Keywords: low Reynolds, testing, turbulence model, low pressure turbine blade
Tracing of the ion trajectories would give a large amount of information about the ion thruster. The genuine method is introduced that an interrelation of the results of a full simulation of the ion trajectories with the results of an experiment, measuring the emittance of the source would give an access to the plasma parameters of the discharge in the ion thruster. Furthermore measuring the emittance in different distances would give valuable information about the thrust vector and its variation and also beam forming itself with prospective evaluation of the space charge. Usage of emittance measurements for optimization of basic aperture for extraction system can give reliable indication its perfection in terms of divergence and correspondingly lifetime.
The emittance of the beam is the 6D-volume which beam occupies in phase space of coordinates and impulses. For the computer modelling is the KOBRA3-INP code used. KOBRA is a Vlasov-solver. It starts with the solution of the Poisson equation. A space charge map is built during the ray-tracing. This particle distribution map is included in the following iteration step to obtain the self-consistent particle distribution.
The method is developed for measurements on a Mini Radio Frequency Ion Thruster (RIT) but can be used for any ion thruster technology. These type of thrusters are candidate for many future science and Earth Observation missions based on formation flying and fine attitude control. Although this method is well known for the high energetic ions like the ion beam injectors for the TOKAMAK heating, the method is new for such low energy ions.
Measurement of the emittance is performed using the slit-wire-method. The primary ion beam is separated into a bunch of beamlets by passing an array of slits. Behind this slit array in an appropriate distance the spatial distribution of the beamlets is scanned with a thin wire. The position of the wire is quantified with a precise potentiometer. To obtain the four-dimensional transversal beam emittance the primary beam can be splitted by two perpendicular slit arrays. To reduce distortion of the profile measurement by secondary particles, a repeller voltage can be applied on the slit system. With this method each data point is characterized by its position, divergence angle and intensity. Experimental results and comparisons with computer modeling will be presented.
Keywords: emittance, ion thruster, ion-optic system, ion beam
Special attention is recently paid to small spacecraft (SSC) with a mass of a few to several tens of kilograms. But for a SSC to become controllable there is a need to develop a highly efficient and compact thruster for the orbit correction and keeping. Appropriate propulsion system should be designed in view of the limitations for mass and power on board. The propulsion system must be lightweight, space-saving and cheap with high efficiency in power consumption of up to about 25 W.
The ablative pulsed plasma thrusters (APPT) are promising for such purposes, as they have several important advantages: instant readiness for operation, extremely low inertia and the almost complete absence of the afteraction pulse, the possibility for precise impulse control, long enough lifetime, as well as the linear variation of the thrust control characteristic.
A family of small APPT models with ultra low energy developed and manufactured at the RIAME MAI is reviewed in the paper. The test results allow considering such thrusters as the most promising for the SSC orbit correction.
A physical-mathematical model developed at the RIAME MAI is presented in the paper also. This model describes operation of the low-energy and low-power APPT. Its computer implementation makes it possible to trace the influence of variations in different input data on the APPT performance. A comparison of theory and experiment revealed good enough agreement of the results.
A set of the electrical circuit parameters (inductance, capacitance) is defined for the ultra-low power APPT, which provide maximum operation efficiency.
Keywords: plasma acceleration, plasmoid, ablative pulsed plasma thruster
Presented paper is devoted to solution to the problem of blade fragments localization during its accidental breakage with the help of proposed design of a combined case which consists of the metallic base and layer of untreated aramid yarns tightly wound on the metal substrate.
The main purpose is to prevent the combined case damage of aircraft structure dangling from the accident decayed fragments of the compressor including a torn shoulder blade or its fragment.
In the frame of this work a robust finite element combined case modeling methodology, in which there is an approach for modeling of winding impregnated aramid yarns, was created. Method for construction and configuration of computer system based on a three-dimensional code LS-DYNA, which provides authentic simulation of multi-layer composite materials used in protective systems for localization of engine broken blades, is implemented.
Developed numerical technology of calculation of structural elements dynamic deformation is verified by the results of field tests.
Keywords: combined case, impregnated aramid fabric, deformation, broken scapula, strength, armor protection, calculation, finite element method
Control and navigation systems
The paper considersthe problem of synthesis ofa fuzzy-logic based control law for the Raptorsmall-size unmanned helicopter, which operates in thepresence of parametric and external disturbances, with incomplete measurement of the state vector. At that the angle error and its rate of change are available for measurement.
The fuzzy-logic basednavigation controller is developed by using the Mamdani approach. It is built separately for outerand inner control loopcircuits. One of the specific features of the fuzzy-logic based controller consists in the fact that it can be used to control a complex object, the precise mathematical description of which is absent.In addition to that the fuzzy-logic based controller is able to preserve the quality of control in the presence of parametric and external disturbances.
The main difficulty in designing a fuzzy controller consists in determining its tuning.The tuning of fuzzy-logic basedcontroller is performed according to the results of the functioning of the auxiliaryfixed-logic basedcontrollers in orderto simplify the control law synthesis. Such fixed-logic based controllerscan be implemented sufficiently easily, but they do not provide the required quality of control.Thetuning of the fuzzy-logic based controller for the inner loop of angularstabilization is performed based onthe results of functioning of the auxiliary controller, which is built according to the backstepping method with the usageof the Lyapunov function. The tuning of the fuzzy-logic based controller for theouter loop of spatial motion is performed according to the results of functioning of thepreviously developed controller with observers.The outer control loop generates the command for the inner loop in the form of the desired pitch and roll angles.The inner loop generates the command for the deflection ofthe helicopter control sticks. Each channel uses two input signals: the command error and its rate of change.At thateach input and one output use seven membership functions ofGaussian type, whichare connected byforty-nine rules.
The control algorithm efficiency is confirmed throughsimulation according to the requirements of the ADS-33Estandard, which is a recognized criterionof evaluation of handling qualitiesof military helicopters. The pirouette maneuver was used for helicopter flight simulation.The developed control algorithm was also tested on the laboratory helicopter test rig with two degrees of freedom.The experiment has confirmed the efficiency of the fuzzy-logic based controller in the presence of external and parametric disturbances.
Keywords: fuzzy logic, small-size helicopter, control law synthesis
The aim of this work is to develop a model of non-contact motors for system of simulation and design of electronic devices OrCAD/PSpice. The models are contributed to automate the design, simulation, and optimization of high-precision actuators according to both the properties of the electronic drive control units and the properties of gears and actuators.
The contactless motor model is based on the principle of electromechanical analogy. To construct the model, we use the standard model of electric components available in OrCAD libraries, such as resistors, inductors, controlled current and voltage sources. For the simulation of interaction of currents windings arranged at different angles with the rotating magnetic field of the rotor, abstract units used performing the calculation of mathematical functions (sine, cosine, square root), also available in standard libraries OrCAD. To perform calculations on values in vector form, additional models were developed.
Adequacy of the model is provided by the analogy of differential equations describing electromagnetic and mechanical phenomena in the engine and differential equations implemented simulation circuitry. Operability of the contactless engine model is tested on the model of the drive.
The model of the engine built in the form of electrical equivalent circuits can be combined in OrCAD with circuitries of control devices such as electromechanical models of gears, loads, sensors in the model higher level of complexity for solving various practical problems (definition of traction properties, synthesis and parametric optimization of control devices, etc.).
Keywords: brushless motor, electro-mechanical analogy, simulation
Technical cybernetics. Information technology. Computer facilities
Criterion for the distribution of elementary queries to processors naturally defined as receiving a minimum processing time of queries when all the processors would have completed its work at the same time , while , of course, necessary to keep the order of processing of elementary queries on each processor in accordance with the terms of [1,2].
We can apply the natural distribution of elementary queries to processors in accordance with the rule, when the i-th (i = 1 , ..., r) processor receives elementary queries with numbers i, r + i, 2r + i, 3r + i, 4r + i, 5r + i, 6r + i, ...
In  we proposed quasi-optimal distribution method , when the i-th (i = 1 , ..., r) processor receives elementary queries with numbers i, 2r +1 — i, 2r + i, 4r +1 — i, 4r + i, 6r +1 — i, 6r + i, ...
This article provides an evaluation of the effectiveness of quasi-optimal distribution method in a multiprocessor database.
We have received query execution time in a multiprocessor database for natural and quasi-optimal order of their distribution; minimum and maximum limits of time for performing queries in separate processors for natural and quasi-optimal order of distribution of elementary queries; proof of the effectiveness of the quasi-optimal distribution based on the absolute and relative decrease queries execution borders using the quasi-optimal instead of a natural distribution.
We have received a number of numerical results for execution time of the query consisting of a conjunction of elementary queries. These results confirmed the effectiveness of the quasi- optimal distribution.
Keywords: database, multiprocessor computer, queries, distribution of elementary queries, optimization
Radio engineering. Electronics. Telecommunication systems
Recently Communications Satellite Corporation (COMSAT) has been rapidly developing . In this connection, there is a need to work out antenna systems with high power gain (about 35-60 dB), and coverage area, which is a cone of revolution with a vertex angle of 8,7º. Such antenna systems may be created either in the form of a multibeam antenna or a phased array antenna. It is well known that phased arrays have redundancy emitters compared with their theoretical minimum quantity , but this phenomenon is poorly studied.
This article presents the directional characteristics of phased array antennas with circular and square aperture within the different positions of the elements. Horn antennas with round and square aperture were used as emitters of phased arrays. As a result the dependence of the level and position of side lobe interference from a fixed number of emitters with the fixed dimension of phased array was greaped, as well as the dependence of redundance coefficient from the amount of redundancy and the emitter levels of the interference maxima for different efficiency coefficients. A comparative analysis of the dependence stated above was held for various identical in size antenna gain of phased array antennas.
The analysis determined the dependence of the interference sidelobes from radiators redundance coefficient. It helps to minimize the computing power required for the beam steering of phased array antennas, as well as to improve the constructive and technological parameters.
In the result the best formation structure of phased array antenna was chosen in terms of minimum quantity of emitters and the level of interference maximum that is not exceeding the level of side lobe. It has been established that the best phased array is considerably higher than the coefficient of highest redundancy identical multibeam antenna array described in [2 ] and the one, that consists of the multibeam «large aperture» emitters. Based on the results it is concluded that the use of phased arrays is not always justified and does not lead to the desired results, and therefore further detailed researches are required in development of phased array antennas or multibeam antenna arrays for vehicle-borne antennas of Communications Satellite Corporation.
Keywords: phased array, global satellite communications, aperture emitter, side lobe interference, coefficient redundancy, the minimum number of emitters, the directivity pattern
This article discusses the numerical simulation of shielded planar microwave devices in the final stages of their designing. The aim is enhancing the reliability of simulation results and improving obtained characteristics of fabricated devices. Microwave filters of different designs and ranges of frequencies from 1 to 20GHz made on polycor substrates from 0.25mm to 1mm thick were measured. Numerical modeling of microwave filters was performed by 3D finite element method (FEM) and 2.5D method of moments (MoM) using AWR EMSight. Conductors were simulated in two ways: infinitely thin sheet and metals with finite thickness. In 2.5D MoM metal thickness was modeled by adding new dielectric layer with two infinitely thin sheets connected by vias at all edges. Then numerical results were compared to the experimental data while FEM showed the best agreement with experiment. To explain the differences between FEM and MoM results of simulations, existing methods for modeling of planar microwave devices were briefly reviewed. Strengths and weaknesses of planar microwave devices simulation software based on the MoM were identified. None of the widely known programs based on the MoM appears to allow modeling complex shielded planar microwave device with accuracy comparable with FEM. Eventually, the task of developing a new modeling program based on MoM arises. With mixed potential integral equation formulation chosen to solve the problem, the software will implement 3D conductor model with finite thickness using full-wave Green's functions of a rectangular cavity with uniaxial anisotropic multilayered dielectric media.
Keywords: method of moments, boundary elements method, planar microwave device, numerical methods, electrodynamics, integral equations
The necessity for high precision comparison of time scales arises in various fields of science and technology: from the transmission and distribution of energy and telecommunications systems to the time and frequency national laboratories. A unified state system of time can serve as an example of the latest category and in the frame of which the secondary national standards of time and frequency recreate the national time scale.
The main limitation of the current in-house technology for comparisons with the help of GNSS signals, which are used by the International Bureau of Weights and Measures in the formation of Coordinated Universal Time UTC, is the resulting estimates drift of time scales difference which is associated with the change of systematic delays in the spacecraft, as well as in the navigation receiver. This limitation can be overcome by the use of only phase measurements to estimate the difference of time scales.
If you are working only on the phase measurements a so-called problem of ambiguity resolution arises. For its successful solution apart from the high accuracy of the used models we have to know the difference between zenith tropospheric propagation delays of navigation signals with high accuracy. In the case when the distance between stations is less than ~ 50 km the delay is almost the same and it can be ignored, but otherwise the difference between the zenith tropospheric delays must be estimated a priori or with the rest parameters.
The aim of this work is to create a system of comparison for time scales using the measurements of GNSS which is based on Common View technique with difference evaluation of zenith tropospheric propagation delays of navigation signals.
The first step is ambiguity solution to the so-called wide-lane combination of measurements that can simplify further ambiguousness resolution for ion-free combination.
At the second step, at the same time we estimate the difference between the time scales of receivers and zenith tropospheric propagation delays of navigation signals for all available space vehicles with weights depending on the angle of elevation.
The results of comparisons are consistent with other technologies with a precision of 75 ps. Thus, this approach can serve as a basis for the construction of high precision comparison systems.
Keywords: GNSS, Common View, time transfer, integer ambiguity resolution
The important problem that is considerable through the electromagnetic compatibility (EMC) analysis is to determine the spatial-frequency distribution of the device under test (DUT) radiation in both the near and far field. This is similar to one of the antenna systems analysis problem where the antenna directivity and gain should be determined with high accuracy. The conventional solution of both problems is provided by the frequency domain measurements of the complex amplitudes for each frequency at different space points. This procedure can be carried out both in the far field and near field with some modifications. At the same time, near-field measurements provide better accuracy and reduce the measurement setup requirements. On the other hand near field measurements allow a direct computation of the far field in a limited sector of space angles. The proportions of the sector for planar measurement scenario depend on the object and measurement plane dimensions as well as the distance between them. In accordance with the equivalence principle  the DUT may be replaced with a set of electric or magnetic dipoles. This simple dipole model allows analyzing the radiation pattern in the wider space region. The proposed technique for the estimation of spatial-frequency DUT radiation can be implemented by using the identification of the dipole model parameters based on the near-field measurement.
The presented approach can be also effectively used in EMI analysis problem. However, the EMI fields radiated by complex devices are often random. Then, the described procedure may be performed for the cross-correlation characteristics of the stochastic field sources.
In this work, the author proposes a parametric identification procedure for stochastic EMI sources localization based on two-point time-domain planar scanning in the near field region of the radiation structure. As a model of a radiating structure, the set of electrical dipoles arranged on a grid in object plane is proposed. Some simplifications of the two-point scanning measurement setup are introduced for two typical cases of mutually correlated sources. The improvement of the EMI sources space resolution is achieved by the application of the proposed parametric identification procedure, which includes the model order selection by using the information criterion and model parameters designation with the parametric spectral estimation method. An example of equivalent effective sources spatial localization inside the real complex device based on the simulation and measurement results is presented.
Keywords: dipole model, near-field, stochastic field, two-point scanning, correlation spectra, parametric identification
Economics and management
To define the key aspects to organizational changes to the integrated aero-engine sector of industry.
To examine the problem of integration in the area of aero-engine industry it’s offered to apply the systematic approach as it enables to determine cause-effect relations among components of the system and findings.
The science of economics defines «integration» as a multi-aspect category. It is possible to sort out the definitions of this phenomenon by a complex approach that studies definition as an integral formation with its characteristic systemic features and as a process, including certain phases of integration growth (build-up). The mechanism of integration is based on a synthesis of qualitative generalization of functional forms of production management, on the level of systemic changes on production plants and on the internal scheme of their internal organizational integrity. The classification of integration unions and the analysis of their activities allows us to define for corporations some efficient modern ways for further development. The activation of the national production plants potential for innovation requires a consistent systemic reorganization of the industry. The operation experience of some high-tech corporations displays the efficiency of the divisional management model which takes into account the specific segmentation of the international aircraft market. The creation of the highly efficient JSC «UEBC» based on creation of market-oriented business units (divisions) is aimed at an efficient placement of Russian aero-engine industry products on the markets and, as a result, the strengthening of the reputation of Russia as a world high-tech power.
The present study is a basis for a further research on the problem of organization of production of competitive aero-engines.
The originality of this research lies in the systematization and generalization of some theoretical regulations and the operational experience of some integrated business units in the high-tech sectors of the economy.
Keywords: integration, building of aero-engines, restructuring of the industry, divisional management structure
Historically, the development of the domestic aerospace industry did not imply the use of market mechanisms to regulate the nomenclature and volumes of space rocketry, with issues of competitiveness of products in the domestic and international market is not a priority. However, currently, while maintaining priority meet state needs to create SRH as a prerequisite acts competitiveness of their products in the global market space . This condition is necessary for the preservation and development of the space industry as an independent high-tech industry.
Upon reaching the desired result implementation of the current strategy of development of space industry for the period 2015 to the space industry should be provided with the release profile production has the technical level corresponding to the best world standards rocket and space technology.
To determine the extent to which the objectives of the analysis of the technical level and competitiveness created SRH .The technical level is a system of indicators that characterize the qualitative properties of the product, the overall efficiency of its technical systems and compliance with the best world analogues.
The main methods of evaluation of the technical level of aerospace hardware include:
— Method of specific indicators . Apply to products characterized by a fairly complete one or more basic performance characteristics (starting weight, power capacity , the number of transponders resolution electro-optical equipment , etc.);
— Ball method . Used when it is impossible to distinguish the main (basic) technical parameter . Based on expert significance of the technical parameters of the product;
— The method of integral multiplicative indicators. Based on determining the effect of a set of basic technical characteristics of the product on the efficiency of its operation.
In general, the application of the methods considered complex allows to determine the technical level of developed and manufactured products RKT , track time dynamics of their development , and to assess their competitiveness against foreign counterparts.
Keywords: aerospace technology, spacecraft, space platform, performance characteristics, the technical level of competitiveness
The aim of the research was to develop a project managing informational system (IS) using Microsoft Enterprise Project Management (EPM) that will realize the interaction between the main project participants. The unified information space created by the system allows to monitor the realization of project stages and accelerates the process of decision-making.
Using theories of structural analysis, system analysis, reengineering of business-processes, an informational interaction model was worked out.
The unified information space formed by the system allows to control the project during its whole life cycle. It accelerates decision-making in case any deviation appears. It supplies the participants with all necessary information about the product, eliminating communicative barriers between them. Thus, the informational system helps to manage the project more effectively. As a result, a technique of creating an informational interaction system was developed, main requirements to the realization of the innovational project financed within the federal-oriented program were put forward.
The practical value of the work is that the informational interaction helps to manage the project more effectively. The background of this work is connected with innovational activity of JSC «UMPO» — the development of a highly-technological product — the components of TV3-117 and VK-2500 engines. The fact is that the successful realization of this innovational project is of state importance. However, it faces a great informational challenge: an intricate nomenclature, complicated nature of the product, space distance between the participants of the project, control limit and many others. It solves a number of problems, including n abundance of information about a product and communicative barriers between participants of the project activity.
Keywords: intercorporate information system, project management, a single information space, the project life cycle
Subject of research
ERP-systems of aircraft machinery industry
Object of study
Industry: aircraft machinery
Object — the aviation industry of Russia.
The theme of the study: «Audit Of Management Systems Of Economic Objects In Aviation Industry».
To develop and improve the technology of audit of automatic enterprise management systems (ERP-systems audit) of aircraft machinery industry in order to enhance the quality of management of aviation enterprises.
Problems to be solved in the course of achieving the goal
— Development of the directions of ERP-systems audit of aviation enterprises;
— The development of the methodology for ERP-systems audit in different aspects, such as information system itself, the technology infrastructure of ERP-systems, information security in ERP-systems and the performance of the IT-department in aviation enterprise;
— Identification of the industrial specialty of the aviation enterprises’ ERP-systems audit;
— Development of the recommendations for the contents of the aviation enterprises’ ERP-systems audit results.
Method of work
The research methodology is based on the provisions and principles of the theory of industrial organization, functional analysis, general management theory.
Information support of the study
The researches, made in aviation enterprises.
The data, gathered during the collaboration with several aviation enterprises; the data from the open sources, periodical literature and Internet.
Scientific novelty (the results)
Scientific innovation is contained in the development of methodological concept of automatic enterprise management systems’ audit for economic objects of aviation industry, the development of audit directions, the contents of works, fulfilled during the aviation enterprise ERP-systems audit.
Keywords: management system of economic object, information security, IT-audit, effectiveness of management system