Problems of improper dynamic system analysis and synthesis with regard for transfer zeroes

The notion of a transfer zero as applied to improper dynamic systems is considered. An algorithm that makes it possible to reduce the calculation of improper system zeroes to finding ordinary system zeroes is presented. A method for providing the specified position of a transfer zero set in the improper dynamic system having an equal number of inputs and outputs is proposed.     

Synthesis of a combined system for precise stabilization of the Spektr UF observatory. I

The paper presents the first part of results of basic research for development of a combined system of high-precision stabilization of the optical telescope for the international observatory Speckr UF (currently under design) planned to study emission of stars in the UV waveband. A new direct method used in these studies for calculating program controls is described. The results of numerical experiments are presented.     

Absorbed doses in October–November 2003 onboard the Russian segment of the International Space Station according to the data of radiation control system

The results of radiation control onboard the Service Module of the International Space Station are considered for the period of increased radiation background from 28 to 30 October, 2003. The values of additional irradiation dose caused by strong solar proton events on October 28 and 29, 2003 are obtained. A comparison is made with similar data obtained in the periods of disturbed radiation conditions of fall 2001. The results of estimating the dependence of the absorbed dose on the shield thickness, based on the onboard measurements, are presented. It is established that the daily-averaged dose power onboard the International Space Station increased after the solar proton events of October 2003.     

Peculiarities of long-wave radio bursts from solar flares preceding strong geomagnetic storms

Radio bursts in the frequency range of 100–1500 kHz, recorded in 1997–2000 on the INTERBALL-1 satellite during the solar flares preceding the strong geomagnetic storms with D _st < ?100 nT, are analyzed in this paper. The observed long-wave III-type radio bursts of solar origin at frequencies of 1460 and 780 kHz were characterized by large values of the flux S _f = 10^?15 ?10^?17 W/m² Hz and duration longer than 10 min. The rapid frequency drift of a modulated radio burst continued up to a frequency of 250 kHz, which testified that the exciting agent (a beam of energetic electrons) propagated from the Sun to the Earth. All such flares were characterized by the appearance of halo coronal mass ejections, observed by the LASCO/SOHO, and by the presence of a southward B_z-component of the IMF, measured on the ACE and WIND spacecraft. In addition, shortly after radio bursts, the INTERBALL-1 satellite has recorded the fluxes of energetic electrons with E > 40 keV.     

Dependence of helicopter lifting system loading on temperature variations in composite material properties

The results of studying the influence of physical and mechanical properties of composite materials on balancing characteristics and loading of a helicopter under changes of climatic operational conditions are described.     

Application of oil dispersion to enhance the efficiency of aircraft GTE oil system operation

The data obtained in the course of experimental studies of a promising technique for the MS-8P engine oil cleaning by its dispersion are presented. It is obtained that as a result of dispersion, the sizes of solid particles in oil appearing in the process of wear of the triboengineering system elements in the aircraft GTE rotors do not exceed 3 μm making it possible to increase the engine oil service life and durability of rotor bearings.     

A spherical dome in the temperature field

An exact solution of the uncoupled three-dimensional thermoelasticity problem for a spherical dome (hangar) is constructed. Displacements and stresses in the structure are determined as two-fold series with respect to solid spherical harmonics and trigonometric functions.     

Application of neural networks for the design of flight control algorithms. II Adaptive tuning of neural network control law

In this paper, we consider different approaches for the neural network controller tuning in the flight control system. Two of the most common tuning approaches in the adaptive control theory are applied. The first one uses parameter identification technique and consists in solving a real-time regression problem for the control law. The second approach is based on the Lyapunov direct method, which utilizes a tracking error as an absolute measure of tuning performance. The neural network control law are designed for the three-axis flight control problem and tested on the full nonlinear model of a fighter aircraft. Closed loop simulation results are presented and two adaptation algorithms are compared in the case of abrupt change of aircraft dynamics.     

Material deformation curve approximation in strength and stability analysis

A deformation curve approximation method applicable for materials without yield line and characterized by simple realization and a possibility of explicit representation of the stress-strain dependence is presented. The simplest approximation variant makes it possible to find critical stresses for beams or plates in the closed form.     

Numerical simulation of a flow around airfoil using inviscid gas equations

A method for determining a field of inviscid gas equation application in finding the aerodynamic characteristics of bodies is proposed; as an example, use is made of airfoils for which extensive experimental data are available. The comparative analysis of physical and numerical simulation results showed a good verification of the method presented.