An application of embedology to spatio-temporal pattern recognition

The theory of embedded time series is shown applicable for determining a reasonable lower bound on the length of test sequence required for accurate classification of moving objects. Sequentially recorded feature vectors of a moving object form a training trajectory in feature space. Each of the sequences of feature vector components is a time series, and under certain conditions, each of these time series has approximately the same fractal dimension. The embedding theorem may be applied to this fractal dimension to establish a sufficient number of observations to determine the feature space trajectory of the object. It is argued that this number is a reasonable lower bound on test sequence length for use in object classification. Experiments with data corresponding to five military vehicles (observed following a projected Lorenz trajectory on a viewing sphere) show that this bound is indeed adequate     

Space radiation quality factor investigations with “NAUSICAA”-device on board the “MIR” space station

The estimation of radiation quality factor in space flights is a serious problem of space dosimetry. The solution of this problem is based on LET-spectra measurements. The “NAUSICAA”-device installed on the “MIR” station has a detector with a large geometric factor, that gives the possibility of measuring LET-spectra with sufficient statistic in relatively short time interval and hence the corresponding Q. LET-spectra are accumulated through 24 hour periods and equivalent dose (H), absorbed dose (D), quality factor and flux (F) are measured every 10 minutes. The obtained data permit the estimate of the diurnal Q and Q in South Atlantic Anomaly. These values vary in the range of 1.4 – 2.2. The analysis of these values including their comparison with the calculated results is given in this paper.     

Built-in test maturation concepts using test program set andrelational database technologies

Continual improvement of avionic built-in test (BIT) is critical to mission readiness and capability. This paper discusses how test program set (TPS) and relational database (RDB) technologies can be used for this purpose. Important aspects for continually improving avionic BIT and TPS operation are discussed     

Efficient solution and performance analysis of 3-D positionestimation by trilateration

A new exact, explicit, and computationally efficient solution for three-dimensional (3-D) position estimation based on range measurements from three stations is proposed. The simple polynomial-type form of the new algorithm facilitates the performance analysis. Formulae are provided for both the variance and the bias of the position estimates. The systematic error is a joint effect of both the measurement noise and the system nonlinearity and its magnitude cannot be ignored if highly accurate localization is required. Performance evaluation results are presented for various conditions     

Planetary Protection Policy (U.S.A.).

Through existing treaty obligations of the United States, NASA is committed to exploring space while avoiding biological contamination of the planets, and to the protection of the Earth against harm from materials returned from space. Because of the similarities between Mars and Earth, plans for the exploration of Mars evoke discussions of these Planetary Protection issues. US Planetary Protection Policy will be focused on the preservation of these goals in an arena that will change with the growth of scientific knowledge about the martian environment. Early opportunities to gain the appropriate data will be used to guide later policy implementation. Because human presence on Mars will result in the end of Earth's separation from the martian environment, it is expected that precursor robotic missions will address critical planetary protection concerns before humans arrive.     

An Application of Kalman Filtering and Time Averaging to Inertial Guidance Evaluation

A method is developed for estimating circular error probable values and circular error probable rate values of an inertial navigation system using the concepts of Kalman filtering and time averaging.     

EURECA and SGF performances

The EURECA platform offers unique characteristics for microgravity research: a very low level micro-gravity spectrum and a long operation time for recoverable experiments.

Five core facilities on board will perform an impressive number of experiments. The main purpose of the Solution Growth Facility (SGF) is growing crystals at low temperatures by using the double diffusion technique in three compartment reactors. The micro-gravity eliminates the convection in the liquid, while Marangoni convection is avoided by the absence of free surfaces. The thermal gradient in the buffer zone is better than 0.01°C/cm. Turbulence is eliminated by control of the valve rate and by a pressure compensation system. All surfaces are coated with Halar. The diffusion rate can be controlled by the use of filters. The SGF contains three independently controlled reactors.

A forth reactor contains an experiment aiming at measuring the Soret coefficient of twenty binary organic mixtures and aqueous electrolyte solutions.     

An anticipative adaptive array for frequency-hopping communications

To fully utilize the theoretical processing gain achievable when an adaptive array and frequency hopping are combined, frequency compensation is required. Improved versions of an anticipative adaptive array are examined that provide efficient compensation by adapting the complex weights at each antenna element to the appropriate values for a carrier frequency before that frequency is received. The underlying adaptive algorithm used is the maximum algorithm. Computer simulation results are used to compare the different versions of anticipative processing. These results show that an appropriate version ensures the rapid convergence of weights to values that provide wideband nulling of the interference and noise     

Resonant sensor for high accuracy pressure measurement usingsilicon technology

A resonant-element transducer developed for aerospace applications using micromachined silicon technology is described. The sensor is a beam supported over a square diaphragm. The resonant frequency of the beam is proportional to the applied pressure on the diaphragm. Results presented show that the prototype's performance rivals that of current high-accuracy pressure transducers