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Spline-Based Smoothing of Airfoil Curvatures

Spurious curvature oscillations and bumps are suppressed. Constrained fitting for airfoil curvature smoothing (CFACS) is a spline-based method of interpolating airfoil surface coordinates (and, concomitantly, airfoil thicknesses) between specified discrete design points so as to obtain smoothing of surface-curvature profiles in addition to basic smoothing of surfaces. CFACS was developed in recognition of the fact that the performance of a transonic airfoil is directly related to both the curvature profile and the smoothness of the airfoil surface.

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Reducing Spaceborne-Doppler-Radar Rainfall-Velocity Error

A combined frequency- time (CFT) spectral moment estimation technique has been devised for calculating rainfall velocity from measurement data acquired by a nadir-looking spaceborne Doppler weather radar system. Prior spectral moment estimation techniques used for this purpose are based partly on the assumption that the radar resolution volume is uniformly filled with rainfall. The assumption is unrealistic in general but introduces negligible error in application to airborne radar systems. However, for spaceborne systems, the combination of this assumption and inhomogeneities in rainfall [denoted non-uniform beam filling (NUBF)] can result in velocity measurement errors of several meters per second.

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Stochastic Analysis of Orbital Lifetimes of Spacecraft

A document discusses (1) a Monte-Carlo-based methodology for probabilistic prediction and analysis of orbital lifetimes of spacecraft and (2) Orbital Lifetime Monte Carlo (OLMC) — a Fortran computer program, consisting of a previously developed long-term orbit-propagator integrated with a Monte Carlo engine.

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Visual Data Analysis for Satellites

The Visual Data Analysis Package is a collection of programs and scripts that facilitate visual analysis of data available from NASA and NOAA satellites, as well as dropsonde, buoy, and conventional in-situ observations. The package features utilities for data extraction, data quality control, statistical analysis, and data visualization.

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A Data Type for Efficient Representation of Other Data Types

Some obstacles to programming of parallel computers are removed. A self-organizing, monomorphic data type denoted a sequence has been conceived to address certain concerns (summarized below) that arise in programming parallel computers. [“Sequence” as used here should not be confused with “sequence” as the word is commonly understood or with “sequence” as used elsewhere to denote another, polymorphic data type that is also relevant to computer programming.] A sequence in the present sense can be regarded abstractly as a vector, set, bag, queue, or other construct. A sequence is defined in terms of the behavior of the operators that can be applied to it without any foreknowledge of the underpinnings of its representation or particular implementation.

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Providing Goal-Based Autonomy for Commanding a Spacecraft

A computer program for use aboard a scientific- exploration spacecraft autonomously selects among goals specified in high-level requests and generates corresponding sequences of low-level commands, understandable by spacecraft systems. (As used here, “goals” signifies specific scientific observations.) From a dynamic, onboard set of goals that could oversubscribe spacecraft resources, the program selects a non-oversubscribing subset that maximizes a quality metric. In an early version of the program, the requested goals are assumed to have fixed starting times and durations. Goals can conflict by exceeding a limit on either the number of separate goals or the number of overlapping goals making demands on the same resource.

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Optimal Planning and Problem-Solving

CTAEMS MDP Optimal Planner is a problem- solving software designed to command a single spacecraft/rover, or a team of spacecraft/ rovers, to perform the best action possible at all times according to an abstract model of the spacecraft/rover and its environment. It also may be useful in solving logistical problems encountered in commercial applications such as shipping and manufacturing.

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