Four-node finite element of a two-dimensional functional spline to simulate a regular aircraft surface

The Gramian matrix of a four-node finite element is obtained using generalized differentiation to calculate a functional two-dimensional interpolation spline. The numerical results of testing that confirm the interpolation process convergence when applying a sequence of functional two-dimensional splines calculated by the method suggested are presented. Also given are the results of solving an applied problem of simulating an external surface of the fighter cockpit canopy.     

Kappa distribution functions and the main properties of auroral particle acceleration

The problem of auroral particle acceleration is analyzed taking into account the filling of the magnetosphere by accelerated particles of ionospheric origin and the trapping of particles between the magnetic and electrostatic barriers. It is taken into account that kappa distributions describe experimentally measured distribution functions better than do maxwellians. The existence of conjugate field-aligned potential drops in the north and south hemispheres is suggested. Field-aligned potential drops are formed if the value of field-aligned current is higher than the threshold determined by the free gazodynamic flow of electrons along field lines. Results of experimental observations showing the possibility of field-aligned potential drop concentration in double layers are summarized. The theory of kinetic double layers is developed taking into account the nonmaxwellian forms of distribution functions. It is shown that the kinetic treatment and the existence of nonmaxwellian distributions lead to real changes in the criteria required for double-layer formation.     

Canopy photosynthesis and transpiration in microgravity: gas exchange measurements aboard Mir.

The SVET Greenhouse on-board the Orbital Station Mir was used to measure canopy photosynthesis and transpiration rates for the first time in space. During the Greenhouse IIB experiment on Mir (June-January 1997), carbon and water vapor fluxes from two wheat (cv. Superdwarf) canopies were measured using the US developed Gas Exchange Measurement System (GEMS). Gas analyzers capable of resolving CO2 concentration differences of 5 micromoles mol-1 against a background of 0.9% CO2, are necessary to measure photosynthetic and respiratory rates on Mir. The ability of the GEMS gas analyzers to measure these CO2 concentration differences was determined during extensive ground calibrations. Similarly, the sensitivity of the analyzers to water vapor was sufficient to accurately measure canopy evapotranspiration. Evapotranspiration, which accounted for over 90% of the water added to the root zone, was estimated using gas exchange and used to estimate substrate moisture content. This paper presents canopy photosynthesis and transpiration data during the peak vegetative phase of development in microgravity.     

Stability analysis of digital linear flight controllers subject to electromagnetic disturbances

High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. Such upsets can degrade the quality of the control signal ranging from a perturbation error over a few sample periods to a permanent error mode or computer failure. Under these conditions, the primary concern of the control engineer is to insure that the closed-loop system remains stable. A stochastic disturbance model and a set of associated stability assessment tools are introduced for determining stability robustness of a nominal closed-loop system subject to electromagnetic disturbances. The focus is primarily on night control applications, but the methodology is suitable for any application where highly reliable digital control is needed. The technique is demonstrated on a simple test example and on a stabilizing controller for the longitudinal dynamics of the AFTI/F-16 aircraft.     

Solar neutron events as a tool to study particle acceleration at the Sun

The Sun provides unique opportunities to study particle acceleration mechanisms using data from detectors placed on the Earth’s surface and on board spacecrafts. Particles may gain high energies by several physical mechanisms. Differentiating between these possibilities is a fundamental problem of cosmic ray physics. Energetic neutrons provide us with information that keeps the signatures of the acceleration site. A summary of some representative solar neutron events observed on the Earth’s surface, including associated X and γ-ray observations from spacecrafts is presented. We discuss evidence of acceleration of particles by the Sun to energies up to several tens of GeV. In addition, a recent solar neutron event that occurred on September 7th 2005 and detected by several observatories at Earth is analyzed in detail.     

Iris recognition technology

IriScan Inc. has been developing an identification/verification system capable of positively identifying and verifying the identity of individuals without physical contact or human intervention. A new technology, using the unique patterns of the human iris, shows promise of overcoming previous shortcomings and providing positive identification of an individual without contact or invasion, at extremely high confidence levels. The video-based system locates the eye and iris; evaluates the degree of occlusion by eyelid and spectral reflection; determines the quality of image focus; and determines the center and boundary of the pupil and the limbus (outer edge of the iris) for processing. The iris is zoned, and the features therein measured and encoded into a 256-byte (2048 bit) IrisCode for enrollment or identification. The presented biometric is compared to an extensive database for identification, or to a referenced IrisCode for verification. Computations and decisions are accomplished at extremely high rates of speed, resulting in processing times of less than two seconds. The process is based on the unique nature and extreme richness of the human iris. The multiple features produce a non-duplicable organ with more than 400 degrees of freedom, or measurable variables. The IriScan process typically uses about 200 of these to create a code which can be compared to an entire database in milliseconds, producing a positive identification with “imposter odds” as high as 1 in 10³⁴     

Relationship of psychological and physiological parameters during an Arctic ski expedition.

Considerable data (primarily physiological) have been collected during expeditions in extreme environments over the last century. Physiological measurements have only recently been examined in association with the emotional or behavioral state of the subject. Establishing this psychophysiological relationship is essential to understanding fully the adaptation of humans to the stresses of extreme environments. This pilot study investigated the simultaneous collection of physiological, psychological and behavioral data from a two-man Greenland expedition in order to model how specific relationships between physiological and psychological adaptation to a polar environment may be identified. The data collected describes changes in adrenal and other hormonal activity and psychological functioning. Levels of cortisol and testosterone were calculated. Factors influencing the plasma profiles of the aforementioned included 24-hour sunlight, high calorific intake of more than 28 000 kJ/day and extreme physical exercise. There was a difference between individual psychological profiles as well as self-report stress and physiological stress.     

Capabilities to Control the Throw-Weight of Ballistic Missiles by the Mobile Radar Data

The methods of estimating the throw-weight of ballistic missiles are analyzed on the basis of radar observations of different phases of BM trajectory from the instant of launch to the instant of impact of detachable elements. Approximate estimations of the accuracy of resulting estimations of mass, which are achieved by modern radars obtaining the data from three main phases of the BM trajectory, are given.     

MEP (Mars Environment Package): toward a package for studying environmental conditions at the surface of Mars from future lander/rover missions.

In view to prepare Mars human exploration, it is necessary to promote and lead, at the international level, a highly interdisciplinary program, involving specialists of geochemistry, geophysics, atmospheric science, space weather, and biology. The goal of this program will be to elaborate concepts of individual instruments, then of integrated instrumental packages, able to collect exhaustive data sets of environmental parameters from future landers and rovers of Mars, and to favour the conditions of their implementation. Such a program is one of the most urgent need for preparing human exploration, in order to develop mitigation strategies aimed at ensuring the safety of human explorers, and minimizing risk for surface operations. A few main areas of investigation may be listed: particle and radiation environment, chemical composition of atmosphere, meteorology, chemical composition of dust, surface and subsurface material, water in the subsurface, physical properties of the soil, search for an hypothesized microbial activity, characterization of radio-electric properties of the Martian ionosphere. Scientists at the origin of the present paper, already involved at a high degree of responsibility in several Mars missions, and actively preparing in situ instrumentation for future landed platforms (Netlander--now cancelled, MSL-09), express their readiness to participate in both ESA/AURORA and NASA programs of Mars human exploration. They think that the formation of a Mars Environment working group at ESA, in the course of the AURORA definition phase, could act positively in favour of the program, by increasing its scientific cross-section and making it still more focused on human exploration.