Vol 8, No 4 (2009)
AIRCRAFT AND SPACE ROCKET ENGINEERING
Chaotic motion of the elastic tether system
Abstract
The motion of the elastic tether system around of its center of mass is considered. The tether system consist of two tip bodies and a weightless elastic tether. The tether is in deployed state. Center of mass of system move along an elliptical trajectory. With the help of Lagrange’s equations of the second kind the equations of motion of the elastic tether system are constructed. As an independent variable the true anomaly angle is chosen. The particular case of motion of a system with the constant length tether is considered. It is shown, that in this case at the system there is a chaos.
9-15
Analytical approximation of aircraft dynamics model in problems of approximate optimal control synthesis
Abstract
An approximate approach to investigating optimal control of an aircraft as a complex object having no complete analytical description is developed. Approximation of practical models (including simulation ones) of the object by analytical designs of various complexity and accuracy for the search of an approximate global solution with consequent iterative refinement on their basis is proposed. The study of helicopter emergency landing manoeuvre is considered as an example. Description of a software complex of refinement and optimization of control laws including the approximation algorithms is given.
16-25
Mathematical model of complex spatial deformation of rotor blades during helicopter arbitrary motion
Abstract
The paper presents the type of equations determining the dynamics of rotor blade complex spatial deformation subject to helicopter arbitrary motion. The equations are deduced without assuming that elastic displacements are small, and are based on dividing the motion into transportation motion and relative motion. As a result, the equations derived are quite compact and easily programmable in the object-oriented environment.
26-34
Analysis of the structure of the third variation of roll moment coefficient during hypersonic flow about bodies of revolution with small spatial surface variations on the basis of differential locality hypothesis method
Abstract
The paper deals with the problem of evaluating the constituents of the third order of roll moment smallness during supersonic flow at small angles of attack of bodies close to bodies of revolution. An expression is derived on the basis of the method of differential locality hypothesis, and the structure of the third variation of roll moment coefficient is analysed, its complete composition is defined. Integral expressions of seven constituents of the third variation are obtained, physical interpretation of each is given.
35-42
Interaction of high-speed particles and temperature control elements of a space vehicle
Abstract
The paper deals with the problem of diagnostics of temperature control elements of space vehicles (heat pipes and temperature control coatings). The results of experiments on simulating high-speed particle interaction with heat pipes and temperature control coatings are discussed.
43-56
History of small space vehicle progress and development at Plesetsk cosmodrome. Current problems of further development
Abstract
A historical survey of small space vehicle progress and development at Plesetsk cosmodrome has been carried out. Its leading role in the creation of multielement low-orbit groups intended primarily for military purposes is isolated. A justified conclusion has been made that the tendency to use small space vehicles as part of multicomponent low-orbit groups is obvious for such areas as space communication, remote Earth sounding, scientific research and developing technologies. The main properties of a space supersystem are formulated and major promising developments in such areas as departmental satellite communication systems, space systems of optoelectronic, radioengineering and radar reconnaissance, ecological monitoring and geodesy are specified.
57-64
Assessing weight efficiency of carrier rockets launched from dirigibles and airplanes
Abstract
A method of comparative analysis of weight efficiency of carrier rocket launches from the Earth’s surface, dirigibles, subsonic, supersonic and hypersonic airplanes is proposed. The method is based on assessing the savings in the required characteristic velocity of carrier rockets launched from dirigibles and airplanes as compared to ground launches and determining the minimal launching mass of the rocket by optimal mass redistribution among the rocket units. The method can be used at the initial stages of design.
65-71
Vibration resistance problem for a space vehicle with single-degree-of-freedom powered gyroscopes
Abstract
Vibration resistance of a space vehicle is estimated in terms of the values of equipment vibration amplitudes. The procedure of estimation is presented as applied to a space vehicle subject to vibrations caused by residual back of balance of powered gyroscopes.
72-79
MECHANICAL ENGINEERING AND POWER ENGINEERING
Full-scale tests of superloaded thrust bearings for hydraulicturbine generators of Sibir hydroelectric power stations of the new generation with unit power of 1 million kw
Abstract
The paper presents the results of full-scale tests of elastic metal-plastic (EMP) segments at the unit load of 10.0 MPa that can take place in hydroelectric units of the new generation with unit power of 1 million kw at large hydroelectric power stations which are planned to be built in Sibir.
80-87
Elastic metal-plastic thrust bearings for combined hydraulic units of pumped storage hydroelectric power stations
Abstract
The paper presents an analysis of serviceability of heavily-loaded elastic metal-plastic (EMP) segments with zero circular eccentricity at hydroelectric unit No. 5 of Ust-Ilim hydroelectric power station. The design of EMP segments suggested and tested by the authors was used in the thrust bearing design of hydraulic-turbine generators by the “Uralelectrotyazhmash” research-and-production association at the Zagorsk pumped storage hydroelectric power plant where they proved to be completely reliable and are still successfully used.
88-94
Theory and methods of designing machines with reduced vibroloading
Abstract
Problems of designing machines with reduced vibroloading are discussed. Theoretical foundations and various methods of reducing machine vibration are proposed: using pneumatic self-pumping balancing device, active vibration isolation, designing electric drives, reduction of mobile machine vibration under moment disbalance etc.
95-109
Criterial approach to constructing empirical models of cutting
Abstract
A model using criterial equations to calculate tool parameters depending on the governing factors is proposed. The model is based on Kronenberg dimensional analysis providing empirical relationships between temperature and tool durability and variables that characterize the cutting process and blank properties. In order to estimate the adequacy of the model it is compared with the experimental data described by traditional empirical relationships in the form of exponential equations with a set of table coefficients, and the results of comparison are presented.
110-115
Some results of analysing theoretical cutting models
Abstract
Zvorykin and Merchant cutting models are considered, complemented with theoretical Reito developments and results of analytical and experimental Oxley investigation. In order to estimate their adequacy and choose the most correct model the data of comparative analysis of the models in question and their combinations with experimental results described by traditional empirical relationships in the form of exponential dependences with a set of table coefficients are presented. Ways to improve the compliance of theoretical models with actual physical phenomena that accompany the cutting process are proposed.
116-122
Wave gearing in valve electric drives
Abstract
Mechanical diagram and design of an electric drive for cut-off valves based on wave gearing is proposed. The drive provides mass reduction, maximum moment increase, element position control, deviation in extreme positions. Two standard sizes of the drive are realized and tested.
123-127
Physical principles of hydrodynamic non-stationarity effect on turbulent flow
Abstract
The paper presents the analysis of the effect produced by non-isothermicity and hydrodynamic non-stationarity on the initiation and development of turbulence. A physical model of a hydrodynamically non-stationary turbulent flow is proposed, based on the previously conducted experimental investigations into the structure of non-stationary turbulent flow that takes place when gas is flowing in the duct.
128-136
Applying Lagrange’s approach to solving a one-dimensional problem of wave propagation in gas in linear formulation
Abstract
Modelling of one-dimensional wave propagation in gas using various numerical schemes is discussed. Alongside the known schemes a scheme of solving an acoustics problem is proposed using Lagrange’s approach to the description of environment motion. The results of numerical solution for three types of initial conditions are compared to those of analytical solution. Conclusions are drawn as to the applicability of the schemes discussed. The possibility of varying by step over the time without reducing the accuracy of the solution is shown.
137-143
ELECTRONICS, MEASURING EQUIPMENT, RADIO ENGINEERING AND COMMUNICATION
Extrapolation of conditions of an information measuring and control system with the iterative algorithm of operation
Abstract
The paper deals with the problems of extrapolation of conditions of an information measuring and control system with the iterative algorithm of operation. An information model is proposed based on the transition matrix. The model’s efficiency is confirmed by the estimation of entropy that surpasses the results obtained by statistical analysis of condition probability.
144-147
Plane high-speed particle transducer
Abstract
The paper presents the solution to the problem of constructing a mathematical model of a high-speed particle ionisation transducer of a plane design. The results of experiments with the plane transducer carried out with the help of a pulsing laser are discussed.
148-160
Hemispherical high-speed particle transducer
Abstract
The paper presents the solution to the problem of constructing a mathematical model of a high-speed particle ionisation transducer of a hemispherical design. The results of experiments with the hemispherical transducer carried out with the help of a pulsing laser are discussed.
161-170
CONTROL, COMPUTER SCIENCE AND INFORMATION SCIENCE
Programme realization of mathematical operations of flow multiplexing and demultiplexing for network models
Abstract
The paper deals with the problem of constructing mathematical models of event flow multiplexing and demultiplexing operations. The flows are described at the level of the first two moments of time distribution between events. The results obtained make it possible to write the equilibrium equations for the flows circulating in network models and to decompose the latter into individual nodes to calculate their characteristics.
171-185
Optimal designing of precision small-size non-platform inertial navigation systems for highly manoeuvrable moving objects
Abstract
The paper presents the results of work on creating a small-size precision non-platform inertial navigation system (NINS) operating under extreme conditions. Special attention is given to elements of methodology and process of designing NINS that were created as a necessary development tool. A new approach to designing NINS calculator is proposed, based on mutual optimization of algorithms and processor architectures.
186-198
199-209
Impulse noise of digital-to-analog converters and its influence on the purity of the spectrum of digital synthesizers
Abstract
The paper presents the analysis of the influence of impulse noise (“glitches”) of digital-to-analog converters on the purity of the spectrum of output oscillations of digital synthesizers. A decorrelation method of reducing the influence of “glitches” of digital-to-analog converters on the level of discrete side components in the spectrum of the output signal of the converter is proposed. The method is based on randomization and does not result in the loss of synthesizer speed. It is shown that the method proposed can find application when designing integral digital synthesizers.
210-217
System designing of function-oriented processors for onboard correlation extreme navigation systems
Abstract
The paper presents the results of investigating optimal realization of the conjunction algorithm, one of the main ones in the complex of algorithms of correlation extreme navigation systems using sensors of geophysical fields. The main result of the investigation is the procedure of algorithm DH-synthesis which makes it possible to synthesize rational architectures of function-oriented processors (FOP). Possible implementation of the conjunction algorithm on the basis of a two-dimensional array of processor elements in VLSI technology is described. The results of DH-synthesis as applied to FOP based on standard microprocessors are presented. The results of developing two generations of actual onboard FOPs for CENSs produced with the use of the procedure proposed are given.
218-236
Using active noise suppression non-adaptive systems with a transfer function model for the reduction of medical equipment noise
Abstract
The paper briefly describes control structures of active noise suppression systems. The possibility of using non-adaptive systems with a transfer function model of the propagation medium to reduce the noise of some classes of objects is shown. A specific example of implementing such systems on the basis of medical equipment is presented.
237-244
Mathematical modelling of the content of electronic educational resources
Abstract
Rules of constructing models of the content of electronic educational resources based on tree oriented graphs are formulated. Mathematical properties of these models are discussed and their integral characteristics are introduced. The proposed approach to content modeling is in good agreement with the SCORM international specifications of electronic education, it complements them with target indicators, algorithms of didactic designing and analysis of educational materials.
245-253
Mathematical modelling of navigation in electronic educational resources
Abstract
The paper presents models of navigation in electronic educational resources based on binary relations and orgraphs. Properties of these models are discussed, their integral characteristics are introduced. The proposed approach to navigation modeling is in good agreement with the international specifications of SCORM and IMS electronic education, complementing them with specific algorithms for aggregating educational objects into electronic courses and helping students to navigate them.
254-263
Problems of synthesis and analysis of the system behaviour control theory on the basis of functional redundancy properties for the class of group automata
Abstract
The possibility of controlling the behaviour of the discrete type systems on the basis of functional redundancy properties is investigated. To form the required output combination of reactions only the properties of the current law of functioning due to the time reserve available at the given moment or artificially created are used for this type of control. A finite determinate automaton is considered as a mathematical model of the system, while the theory of universal enumerating automata is used as the basis for solving the problem. The paper presents a solution of synthesis and analysis problem of the universal automata theory for the class of group automata. A free distributed function library for working with group automata is developed and described.
264-273
Length of restoration sequences for systems without information loss
Abstract
The paper deals with the problem of controlling the behaviour of discrete type systems in case when hardware back-up is absent or faulty, and direct modification of their behaviour in the process of functioning, i. e. controlling the behaviour of these systems on the basis of their functional redundancy, is impossible or not expedient. A finite determinate automaton is used as a mathematical model of the system. The lengths of restoration sequences for the class of group automata are estimated.
274-286