Control of flight vehicles with the adjustable center of mass

We resolve a problem how to control the longitudinal angular motion of flight vehicles (FV) having a system to displace the center of mass in the transverse direction. A structure is determined and a control law is established to start up and shutdown the engines. Formulas to determine the control parameters are obtained.     

Efficiency of a gas screen in the supersonic dispersed flow under conditions of inertial deposition of particles on a protected surface

The results of numerical studying the influence of inertially deposited particles of the condensed phase on the efficiency of a gas screen in a supersonic dispersed flow are presented. The possibility of realizing the Leont’ev paradox on the adiabatic surface region streamlined by a supersonic dispersed flow, involved in attaining the temperature of the surface being protected smaller than the coolant temperature on the permeable section of screen formation is specified.     

Analytical synthesis of functional observers

A technique for constructing the observers to evaluate a linear combination of state variables is considered. We propose an algorithm for analytical synthesis of the minimum-order functional observers based on the nondegenerate transformation of the object model in the state space using the matrix canonization technology. The applicability limits of the technique and the conditions of problem solvability are defined.     

Auroral kilometric radio emission in the period of quiet sun in 1996

The auroral kilometric radio emission (AKR) is the most powerful sporadic radio emission of the terrestrial magnetosphere. It was discovered in 1965 by Soviet scientists in the experiment onboard the Electron-2 satellite [1]. The AKR still continues to stay an object of a large interest and detailed study (see, for example, a review by Gurnett [2]). The mechanism of cyclotron maser instability proposed by Wu and Lee [3] is a commonly accepted mechanism of AKR generation. We have demonstrated the presence of powerful AKR simultaneously in both hemispheres of the Earth in the period from August 1995 to August 1997, including summer-winter periods, on particular examples of registration of this emission in [4] where the directivity and mechanism of the emission were studied. Since in that period AKR was observed in the vicinity of perigees of the satellite orbit in both hemispheres almost at every orbit (3.8 days), we have a possibility to trace in more detail the changes in the emission power from one orbit to another in 1996 during a deep minimum of solar activity.     

Synthesis of a combined system for precise stabilization of the Spektr-UF observatory: II

The paper presents the second part of the results of search studies for the development of a combined system of high-precision stabilization of the optical telescope for the designed Spectr-UF international observatory [1]. A new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions. Using this method, the synthesis of the feedback parameters in the mode of precise inertial stabilization of the optical telescope axis is performed taking the design nonrigidity, quantization of signals over time and level, and errors of orientation meters, as well as the errors and limitation of control moments of executive engine-flywheels into account. The results of numerical experiments that demonstrate the quality of the synthesized system are presented.     

Criteria of applicability of a gas-dynamic approximation of a continuous medium to describing the dispersion of combustion products of rocket propellants

Two criteria for the applicability of a gas-dynamic approximation of continuous medium to describing the dispersion of combustion products of rocket propellants at high altitudes are formulated. Related numerical estimates are given for different launch vehicles and one upper stage with fairly extended boost phases. The use of a continuous medium approximation is shown to have a clear altitude restriction.     

Impact of helio-and geophysical disturbances on thermobaric and climatic characteristics of the Earth’s troposphere

We present the mechanism and the concept of a model of the solar activity impact on thermobaric and climatic characteristics of the troposphere. Both are based on the idea of parametric action. The results of analysis are presented concerning specific features and regularities of changes in temperature regime of the troposphere in the period of variable helio-and geophysical activity, as well as long-term variations of temperature and heat content of the troposphere. The influence of changes in circulation in the atmosphere and ocean on processes in the system atmosphere-ocean-cryosphere is considered: thermohaline circulation of the oceans and energy exchange between the atmosphere and ocean. The revealed regularities find their complete explanation within the context of a model and mechanism of solar activity impact on climatic characteristics of the troposphere that were suggested previously by the authors.     

Problems of control of a re-entry vehicle with a moderate lift-to-drag ratio during its entry into the atmosphere

We consider the problems of control of the angular and trajectory motion of the Kliper re-entry vehicle. This spacecraft with a moderate hypersonic lift-to-drag ratio is designed according to the load-carrying frame scheme. Gas-dynamic engines, a split balancing flap, and an air brake are used as mounting devices of control.     

Application of neural networks for synthesizing flight control algorithms. I neural network inverse dynamics method for aircraft flight control

The application of artificial neural networks for aircraft motion control, in particular, for creation of nonlinear algorithms of the aircraft remote control system (RCS) is considered. Aircraft as a control object is represented as a multidimensional nonlinear dynamic system and nonlinear control methods are used to operate this system. The control loop is constructed using the method of inverse dynamics based on the feedback linearization principle. The nonlinear control law is represented as a neural network being learned (adjusted) by recorded or incoming measurements of motion parameters. Synthesis and testing of neural network control algorithms is performed with the fully nonlinear mathematical model of a maneuverable aircraft for three control channels. Simulation results of the closed system are presented.     

Choice of optimal parameters of a gasodynamic temperature stratification process in the supersonic gas flow

The results of design analysis of the different factor influence on the gasodynamic temperature flow stratification efficiency in the Leont’ev tube are presented. It is justified that the temperature stratification efficiency can be increased at the expense of using longitudinal ribs on the heat exchange surface in the subsonic flow path, and the parameters determining the process can be optimized.