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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 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Fault detection and bypass in a sequence information signal processor

The invention comprises a plurality of scan registers, each such register respectively associated with a processor element; an on-chip comparator, encoder and fault bypass register. Each scan register generates a unitary signal the logic state of which depends on the correctness of the input from the previous processor in the systolic array. These unitary signals are input to a common comparator which generates an output indicating whether or not an error has occurred. These unitary signals are also input to an encoder which identifies the location of any fault detected so that an appropriate multiplexer can be switched to bypass the faulty processor element. Input scan data can be readily programmed to fully exercise all of the processor elements so that no fault can remain undetected.

Peterson, John C.↗
NASA NTRS1999

Phase array calibration orthogonal phase sequence

Methods and systems for calibrating an array antenna are described. The array antenna has a plurality of antenna elements each having a signal with a phase and an amplitude forming an array antenna signal. For calibration, the phase of each element signal is sequentially switched one at a time through four orthogonal phase states. At each orthogonal phase state, the power of the array antenna signal is measured. A phase and an amplitude error for each of the element signals is determined based on the power of the array antenna signal at each of the four orthogonal phase states. The phase and amplitude of each of the element signals is then adjusted by the corresponding phase and amplitude errors.

Sorace, Ronald E.↗
NASA NTRS2005

Methods and apparatus for extraction and tracking of objects from multi-dimensional sequence data

An object tracking technique is provided which, given: (i) a potentially large data set; (ii) a set of dimensions along which the data has been ordered; and (iii) a set of functions for measuring the similarity between data elements, a set of objects are produced. Each of these objects is defined by a list of data elements. Each of the data elements on this list contains the probability that the data element is part of the object. The method produces these lists via an adaptive, knowledge-based search function which directs the search for high-probability data elements. This serves to reduce the number of data element combinations evaluated while preserving the most flexibility in defining the associations of data elements which comprise an object.

Hill, Matthew L.↗
NASA NTRS2003

Method for creating polynucleotide and polypeptide sequences

The invention provides methods for evolving a polynucleotide toward acquisition of a desired property. Such methods entail incubating a population of parental polynucleotide variants under conditions to generate annealed polynucleotides comprising heteroduplexes. The heteroduplexes are then exposed to a cellular DNA repair system to convert the heteroduplexes to parental polynucleotide variants or recombined polynucleotide variants. The resulting polynucleotides are then screened or selected for the desired property.

Arnold, Frances↗
NASA NTRS2008

Methods and apparatus for extraction and tracking of objects from multi-dimensional sequence data

An object tracking technique is provided which, given: (i) a potentially large data set; (ii) a set of dimensions along which the data has been ordered; and (iii) a set of functions for measuring the similarity between data elements, a set of objects are produced. Each of these objects is defined by a list of data elements. Each of the data elements on this list contains the probability that the data element is part of the object. The method produces these lists via an adaptive, knowledge-based search function which directs the search for high-probability data elements. This serves to reduce the number of data element combinations evaluated while preserving the most flexibility in defining the associations of data elements which comprise an object.

Hill, Matthew L.↗
NASA NTRS2007

Variability of Disk Emission in Pre-Main Sequence and Related Stars. I. HD 31648 and HD 163296 - Isolated Herbig Ae Stars Driving Herbig-Haro Flows

Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 pm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 pm region throughout this span of time. In both stars the changes in the 1-5 pm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly-simultaneous photometric data.

Sitko, Michael L.↗
NASA NTRS2008

Variability of Disk Emission in Pre-main-sequence and Related Stars. I. HD 31648 and HD 163296: Isolated Herbig Ae Stars Driving Herbig-Haro Flows

Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 micron in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 micron region throughout this span of time. In both stars, the changes in the 1-5 micron flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly simultaneous photometric data.

Sitko, Michael L.↗
NASA NTRS2005

Lessons Learned Implementing Multi-Mission Sequencing Software

This paper will describe the software and its uses to provide context for its criticality. The different approaches that have been taken to implement the software in a multi-mission format will be outlined. The advantages and disadvantages as well as the lessons learned during development and maintenance of these different architectures will be discussed, Finally. the use of multi-mission software in operations and the lessons learned from using it will be discussed.This paper will provide valuable information to organizations exploring the use of multi-mission software. regardless of whether the change is to minimize spacecraft ground software development time or cost reduction. Similarly. the paper will provide insight into some of the steps that can be taken during software development and operational use that will minimize difficulty later.

software↗
NASA NTRS2010

Flight Avionics Sequencing Telemetry (FAST) DIV Latching Display

The NASA Engineering (NE) Directorate at Kennedy Space Center provides engineering services to major programs such as: Space Shuttle, Inter national Space Station, and the Launch Services Program (LSP). The Av ionics Division within NE, provides avionics and flight control syste ms engineering support to LSP. The Launch Services Program is respons ible for procuring safe and reliable services for transporting critical, one of a kind, NASA payloads into orbit. As a result, engineers mu st monitor critical flight events during countdown and launch to asse ss anomalous behavior or any unexpected occurrence. The goal of this project is to take a tailored Systems Engineering approach to design, develop, and test Iris telemetry displays. The Flight Avionics Sequen cing Telemetry Delta-IV (FAST-D4) displays will provide NASA with an improved flight event monitoring tool to evaluate launch vehicle heal th and performance during system-level ground testing and flight. Flight events monitored will include data from the Redundant Inertial Fli ght Control Assembly (RIFCA) flight computer and launch vehicle comma nd feedback data. When a flight event occurs, the flight event is ill uminated on the display. This will enable NASA Engineers to monitor c ritical flight events on the day of launch. Completion of this project requires rudimentary knowledge of launch vehicle Guidance, Navigatio n, and Control (GN&C) systems, telemetry, and console operation. Work locations for the project include the engineering office, NASA telem etry laboratory, and Delta launch sites.

Moore, Charlotte↗
NASA NTRS2011

Variability of Disk Emission in Pre-Main Sequence and Related Stars. II. Variability in the Gas and Dust Emission of the Herbig Fe Star SAO 206462

We present thirteen epochs of near-infrared (0.8-5 microns) spectroscopic observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (Br(alpha) , Br(gamma), Pa(beta), Pa(delta), Pa(epsilon), and the 0.8446 microns line of O I) along with continuum measurements made near the standard J, H, K, and L photometric bands were measured. A mass accretion rate of approximately 2 x 10(exp 8)Solar Mass/yr was derived from the Br(gamma) and Pa(beta) lines. However, the fluxes of these lines varied by a factor of over two during the course of a few months. The continuum also varied, but by only approx.30%, and even decreased at a time when the gas emission was increasing. The H I line at 1.083 microns was also found to vary in a manner inconsistent with that of either the hydrogen lines or the dust. Both the gas and dust variabilities indicate significant changes in the region of the inner gas and the inner dust belt that may be common to many young disk systems. If planets are responsible for defining the inner edge of the gap, they could interact with the material on time scales commensurate with what is observed for the variations in the dust, while other disk instabilities (thermal, magneto-rotational) would operate there on longer time scales than we observe for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3 years. If the changes are being induced in the disk material closer to the star than the gap, a variety of mechanisms (disk instabilities, interactions via planets) might be responsible for the changes seen. The He I feature is most likely due to a wind whose orientation changes with respect to the observer on time scales of a day or less. To further constrain the origin of the gas and dust emission will require multiple spectroscopic and interferometric observations on both shorter and longer time scales that have been sampled so far.

Sitko, Michael L.↗