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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

A Stabilized Sparse-Matrix U-D Square-Root Implementation of a Large-State Extended Kalman Filter

The full nonlinear Kalman filter sequential algorithm is, in theory, well-suited to the four-dimensional data assimilation problem in large-scale atmospheric and oceanic problems. However, it was later discovered that this algorithm can be very sensitive to computer roundoff, and that results may cease to be meaningful as time advances. Implementations of a modified Kalman filter are given.

data assimilation modified Kalman filter sequentia↗
NASA NTRS2007

Range Measurement as Practiced in the Deep Space Network

Range measurements are used to improve the trajectory models of spacecraft tracked by the Deep Space Network. The unique challenge of deep-space ranging is that the two-way delay is long, typically many minutes, and the signal-to-noise ratio is small. Accurate measurements are made under these circumstances by means of long correlations that incorporate Doppler rate-aiding. This processing is done with commercial digital signal processors, providing a flexibility in signal design that can accommodate both the traditional sequential ranging signal and pseudonoise range codes. Accurate range determination requires the calibration of the delay within the tracking station. Measurements with a standard deviation of 1 m have been made.

range measurement↗
NASA NTRS1964

Pneumotachometer counts respiration rate of human subject

To monitor breaths per minute, two rate-to-analog converters are alternately used to read and count the respiratory rate from an impedance pneumograph sequentially displayed numerically on electroluminescent matrices.

Graham, O.↗
NASA NTRS1966

Logic circuitry used to automatically test shielded cables

Automatic cable tester checks multiple shielded conductors assembly cable connections. The tester uses logic circuitry to sequentially test all conductors and their shields to reveal any connection error in a GO-NO GO test.

Dibb, G.↗
NASA NTRS1967

Evaporant feed device facilitates flash vapor deposition process in vacuum

Mechanism using a helix sequentially feeds prescribed amounts of metal charges into an evaporation boat used for flash vapor deposition of the evaporants onto a substrate in a vacuum chamber. The helix is advanced by external manual controls extending through sealed feed- through devices into the chamber wall.

Hermann, W. A.↗
NASA NTRS1967

Solid-state wide-range low power camera timer for space applications

This paper describes a device for timing sequentially 8 film exposures of a rocket-borne camera with a time interval between each exposure to allow the camera film transport mechanism to step the film from one frame to the next after each exposure. Each exposure time can be independently adjusted from a a fraction of a second to several hundred seconds by changing the value of a timing resistor and/or capacitor. All of the rocket interface circuits have ben designed to minimize the coupling of spurious noise signals into the timer.

Solid state device↗
NASA NTRS1967

Communications and networks

Communications and networks - pulse amplitude modulation, multipliers, photoformer, and sequential circuits

NETWORK↗
NASA NTRS1968

Concept for simplified serial digital decoder

Modular decoder, which lends itself best to special purpose digital equipment using sequential access memories, decodes the first order Reed-Muller codes. It functions as a maximum-likelihood exhaustive-search decoder and is a modular implementation to accommodate codes of any length.

Green, R. R.↗