On-board statistical detection and compensation of anomalous pilot-aircraft interactions

A statistical method for the on-board detection and compensation of adverse oscillations in pilot-aircraft systems is presented. A recursively updated linear model representing the pilot-aircraft system is used to continuously check for stability loss. The instability-related oscillations are detected early, using a statistical hypothesis test. Furthermore, a specially designed stability augmentation system assists the pilot during the instability periods. The method's effectiveness is demonstrated via data obtained from a flight simulator and a detailed simulation model.     

Network-Enabled Missile Deflection: Games and Correlation Equilibrium

The problem of deploying countermeasures (CM) against antiship missiles is investigated from a network centric perspective in which multiple ships coordinate to defend against a known missile threat. Using the paradigm of network enabled operations (NEOPS), the problem is formulated as a transient stochastic game with communication where the appropriate strategy takes the form of an optimal stationary correlated equilibrium. Under this strategy, ships cooperate through real-time communication to satisfy both local and collective interests. The use of communication results in a performance improvement over the noncommunicating, Nash equilibrium scenario. This framework allows us to develop a theoretical foundation for NEOPS and captures the trade-off between information exchange and performance, while generalizing the standard Nash equilibrium solution for the missile deflection game given in [1], The NEOPS equilibrium strategy is characterized as the solution to an optimization problem with linear objective and bilinear constraints, which can be solved calculating successive improvements starting from an initial noncooperative (Nash) solution. The communication overhead required to implement this strategy is associated with the mutual information between individual action probability distributions at equilibrium. Numerical results illustrate the trade-off between communication and performance.     

Performance characteristics of lithium ion cells at low temperatures

The low temperature charge and discharge characteristics of experimental MCMB-Li/sub x/Ni/sub y/Co/sub 1-y/O/sub 2/ cells containing different electrolytes were investigated. The use of low ethylene carbonate (EC)-content electrolyte formulations has resulted in good discharge performance to temperatures as low as -40/spl deg/C. The effect of charge voltage and charge current upon the individual electrode potentials at low temperature was investigated using the three electrode cells (containing lithium reference electrodes). In some cases, lithium plating was observed to occur upon low temperature charge, and found to be facilitated by high charge voltages, high charge currents, and poor anode kinetics. Electrochemical characterization of the cells has helped to establish the conditions under which lithium plating can occur by providing information regarding the polarization effects present at each electrode.     

An experimental and empirical model of electron temperature for altitudes of 500 to 1000 km and for a high solar activity period

On the basis of systematic electron temperature measurements onboard the Interkosmos-19 satellite, an experimental global model of electron temperature T_e has been constructed; namely, a set of samples representing 10 intervals of measured T_e, accompanied by values of the geographic longitude, solar zenith angle, season of the year, Covington index, Dst and Kp, grouped according to the invariant latitude, geomagnetic time and altitude. On the basis of the experimental model, the coefficients of the empirical models for the summer and winter seasons, for geophysically quiet conditions, and for heights of 520, 600, 920 and 1000 km are calculated. For heights of 680, 760 and 840 km with fewer data available, the coefficients are provisional.     

Motor coordination in weightless conditions revealed by long-term microgravity adaptation.

The functional approach to studying human motor systems attempts to give a better understanding of the processes behind planning movements and their coordinated performance by relying on weightlessness as a particularly enlightening experimental condition. Indeed, quantitative monitoring of sensorimotor adaptation of subjects exposed to weightlessness outlines the functional role of gravity in motor and postural organization. The recent accessibility of the MIR Space Station has allowed for the first time experimental quantitative kinematic analysis of long-term sensorimotor and postural adaptation to the weightless environment though opto-electronic techniques. In the frame of the EUROMIR'95 Mission, two protocols of voluntary posture perturbation (erect posture, EP; forward trunk bending, FTB) were carried out during four months of microgravity exposure. Results show that postural strategies for quasistatic body orientation in weightlessness are based on the alignment of geometrical body axes (head and trunk) along external references. A proper whole body positioning appears to be recovered only after months of microgravity exposure. By contrast, typically, terrestrial strategies of co-ordination between movement and posture are promptly restored and used when performing motor activities in the weightless environment. This result is explained under the assumption that there may be different sensorimotor integration processes for static and dynamic postural function and that the organisation of coordinated movement might rely stably on egocentric references and kinematics synergies for motor control.     

Interaction of artificially injected plasma flows with ionospheric plasma

Results of rocket experiments on study of plasma flows (PF) artificially injected by sources separated from vehicles and their effect on medium parameters in ionosphere at altitudes 160:230 km are presented.PF were injected comprising lithium ions with velocities 1,2 x 10⁴ m/sec. and cesium-potassium ions with velocities (1,4–1,5)x10³ m/sec. Mass flow rate in case of lithium PS is 2 mg/sec, and in case of cesium-potassium PS is 0,2 g/sec. During experiments mass-spectrometer measurements of ion medium content in ranges of different ion masses were held, disturbancies of electric fields with frequencies up to 20 kHz and electron flows with energies 0,7keV, 4,6keV and over 40 keV were controlled at distancies from 150m to (500–600)m between plasma source and scientific equipment.     

Functional state of chromatin and proliferative activity of meristematic cells in pea seedlings under various clinostatic conditions.

Data from a complex cytochemical analysis show that the functional state of chromatin and the level of the cell proliferative activity may be reliable cytological criteria for primary structural and functional changes that result in disturbances of plant growth and development. Autoradiographic and cytophotonetric studies made it possible to establish certain differences, induced by fast rotation (50 rev/min) on the clinostat, in the chromatin state and cell reproduction of the pea seedling root meristem for the initial stages of plant development. There were no essential differences for the given parameters under slow (2 rev/min) clinostatic conditions.     

Convective motions in liquid metals for material processings. Numerical simulation of oscillation regimes and effect of rotation

The paper is concerned with the numerical simulation and the analysis of some kinds of flow regimes which can develop in Bridgman and Czochralski systems for material processings. The flows in the liquid phase are investigated considering two-dimensional and axisymmetric models. The time-dependent regimes were studied for a zero-Prandtl-number fluid layer confined inside a two-dimensional cavity of aspect ratio (length-to-height) A=4, involving a stress-free upper surface and submitted to a horizontal temperature gradient. The range of Grashof number was varied up to the conditions at which the flow goes from oscillatory to chaotic type behaviours. The combined influence of the temperature gradients and of the rotations of the crucible and of the seed/crystal was investigated for a Czochralski model. The axisymmetric regimes were studied for a Pr_m=0.015 liquid melt confined inside a cylindrical crucible of aspect ratio (height-to-radius) A_m=2, and coupled to a viscous encapsulant liquid layer (10<Pr_e<1200) of aspect ratio A_e=0.5. A number of steady and (transient) time-dependent flow patterns are identified.     

On ionospheric aerodynamics

This paper presents theoretical methods to determine the gas dynamic and the electrostatic effects due to the interaction caused by a rapidly moving body in the ionosphere. The principles of the methods are derived from the kinetic theory of collision-free plasma. It is shown that the collective behavior of the collision-free plasma makes it possible to use the fluid approach to treat the problems of ionospheric aerodynamics. Various solutions to the system of fluid and field equations that have direct bearing on the ionospheric aerodynamics are presented and discussed. Physical significances of the mathematical results are stressed. Some outstanding unsolved problems in ionospheric aerodynamics are elaborated and discussed.     

Thermoluminescent dose measurements on-board Salyut type orbital stations.

A small, vibration- and shock-resistant thermoluminescent dosemeter /TLD/ system--named PILLE--was developed at the Health Physics Department of the Central Research Institute for Physics, Budapest, to measure the cosmic radiation dose on board orbital stations. The first on-board measurements with this system were performed /by B. Farkas, the Hungarian astronaut/, on the Salyut-6 space station in 1980. The same instrument was used by other crews in the following years. Doses measured at different sites in Salyut-6 are presented. The dose rates varied from 0.07 to 0.11 mGy.day-1. After the first cosmic measurements, the system was further developed. The minimum detectable dose of the new TLD system is 1 microGy, i.e. less by on order of magnitude than that of the former system. The self-irradiation dose rate of the TLD bulbs is also reduced--by more than one order of magnitude--to 10 nGy.h-1, by the use of potassium-free glass for the bulb envelope. This new type of PILLE TLD system is currently on-board Salyut-7. The dose rates /0.12-0.23 mGy.day-1/ measured in 1983 are presented in detail.