Tech Briefs

Miniature Laser Doppler Velocimeter for Measuring Wall Shear

Interference fringes are configured for sensitivity to a velocity gradient.

Posted in: Physical Sciences, Briefs

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Atom Skimmers and Atom Lasers Utilizing Them

Atom skimmers act as conduits and low-pass velocity filters.

Posted in: Physical Sciences, Briefs

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Gears Based on Carbon Nanotubes

Nanometer size gears could be used in molecular-scale machines.

Posted in: Physical Sciences, Briefs, TSP

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Dielectric Heaters for Testing Spacecraft Nuclear Reactors

A document proposes the development of radio-frequency- (RF)-driven dielectric heaters for non-nuclear thermal testing of the cores of nuclear-fission reactors for spacecraft.

Posted in: Test & Measurement, Briefs, TSP

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Neuropsychological Testing of Astronauts

The Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) is a computer program that administers a battery of five timed neuro-cognitive tests.WinSCAT was developed to give astronauts an objective and automated means of assessing their cognitive functioning during space flight, as compared with their own baseline performances measured during similar prior testing on the ground. WinSCAT is also intended for use by flight surgeons to assess cognitive impairment after exposure of astronauts to such cognitive assaults as head trauma, decompression sickness,and exposure to toxic gas. The tests were selected from among a group of tests, denoted the Automated Neuropsychological Assessment Metrics, that were created by the United States Navy and Army for use in evaluating the cognitive impairment of military personnel who have been subjected to medication or are suspected to have sustained brain injuries.These tests have been validated in a variety of clinical settings and are now in the public domain. The tests are presented in a Microsoft Windows shell that facilitates administration and enables immediate reporting of test scores in numerical and graphical forms.

Posted in: Software, Briefs

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Verifying Diagnostic Software

Livingstone PathFinder (LPF) is a simulation-based computer program for verifying autonomous diagnostic software. LPF is designed especially to be applied to NASA's Livingstone computer program, which implements a qualitative-model-based algorithm that diagnoses faults in a complex automated system (e.g.,an exploratory robot, spacecraft, or aircraft). LPF forms a software test bed containing a Livingstone diagnosis engine, embedded in a simulated operating environment consisting of a simulator of the system to be diagnosed by Livingstone and a driver program that issues commands and faults according to a non-deterministic scenario provided by the user. LPF runs the test bed through all executions allowed by the scenario, checking for various selectable error conditions after each step. All components of the test bed are instrumented, so that execution can be single-stepped both backward and forward. The architecture of LPF is modular and includes generic interfaces to facilitate substitution of alternative versions of its different parts. Altogether, LPF provides a flexible, extensible framework for simulation-based analysis of diagnostic software; these characteristics also render it amenable to application to diagnostic programs other than Livingstone.

Posted in: Software, Briefs, TSP

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Initial Processing of Infrared Spectral Data

The Atmospheric Infrared Spectrometer (AIRS) Science Processing System is a collection of computer programs, denoted product generation executives (PGEs), for processing the readings of the AIRS suite of infrared and microwave instruments orbiting the Earth aboard NASA 's Aqua spacecraft. Following from level 0 (representing raw AIRS data), the PGEs and their data products are denoted by alphanumeric labels (1A,1B, and 2)that signify the successive stages of processing. Once level-0 data have been received, the level-1A PGEs begin processing, performing such basic housekeeping tasks as ensuring that all the Level-0 data are present and ordering the data according to observation times. The level-1A PGEs then perform geolocation-refinement calculations and conversions of raw data numbers to engineering units. Finally, the level-1A data are grouped into packages,denoted granules, each of which contain the data from a six-minute ob- servation period. The granules are forwarded, along with calibration data,to the Level-1B PGEs for processing into calibrated, geolocated radiance prod- ucts. The Level-2 PGEs, which are not yet operational, are intended to process the level-1B data into temperature and humidity profiles, and other geophysical properties.

Posted in: Software, Briefs, TSP

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