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At least 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

EUREX D: An expert system for failure diagnosis and recovery in the TCS of the European retrievable carrier EURECA

An expert system for diagnosis and recovery of failures in the Freon cooling loop of the European retrievable experiment carrier EURECA is described. The system demonstrates the feasibility of a functional scope of expert diagnostic systems which appears to be essential for practical applications of such systems in space technology. The scope includes early warning and treatment of incomplete information, fault tolerance, identification of failure superpositions, intelligent reaction to unforeseen events, and detailed status display for optimal recovery action.

Kellner, A.↗
NASA NTRS1987

Diagnosis of vertical motion from VAS retrievals

Satellite-derived temperature profiles are used to determine if reliable estimates of synoptic-scale vertical motion can be obtained from the adiabatic, vorticity, and omega equation techniques. The period of study contains a short-wave trough over the Midwest and a convective outbreak over the middle Mississippi River Valley. Satellite soundings are available at 1-3 h intervals at five times. The emphasis is on assessing the strengths and weaknesses of the three vertical motion procedures, and determining the effects of short-interval observations on the calculations. Results show that the quasi-geostrophic omega equation provided patterns and magnitudes most consistent with observed weather events and 12 h radiosonde-derived motions. The vorticity method produced less satisfactory results, while adiabatic motions were unacceptable. The time derivative term dominated adiabatic motions and was a major influence in the vorticity method. Unrealistic temperature tendencies resulted from the retrieval algorithm; i.e., a diurnal temperature bias extended upwards to 500 mb, and there was a compensating effect at higher levels.

Fuelberg, Henry E.↗
NASA NTRS1984

Transportable, university-level educational programs in interactive information storage and retrieval systems

Pursuant to the specifications of a research contract entered into in December, 1983 with NASA, the Computer Science Departments of the University of Southwestern Louisiana and Southern University will be working jointly to address a variety of research and educational issues relating to the use, by non-computer professionals, of some of the largest and most sophiticated interactive information storage and retrieval systems available. Over the projected 6 to 8 year life of the project, in addition to NASA/RECON, the following systems will be examined: Lockheed DIALOG, DOE/RECON, DOD/DTIC, EPA/CSIN, and LLNL/TIS.

Dominick, Wayne D.↗
NASA NTRS1985

The design of PC/MISI, a PC-based common user interface to remote information storage and retrieval systems. Presentation visuals

This Working Paper Series entry represents a collection of presentation visuals associated with the companion report entitled, The Design of PC/MISI, a PC-Based Common User Interface to Remote Information Storage and Retrieval Systems, USL/DBMS NASA/RECON Working Paper Series report number DBMS.NASA/RECON-15. The paper discusses the following: problem definition; the PC solution; the goals of system design; the design description; future considerations, the research environment; conclusions.

Dominick, Wayne D.↗
NASA NTRS1985

KARL: A Knowledge-Assisted Retrieval Language

Data classification and storage are tasks typically performed by application specialists. In contrast, information users are primarily non-computer specialists who use information in their decision-making and other activities. Interaction efficiency between such users and the computer is often reduced by machine requirements and resulting user reluctance to use the system. This thesis examines the problems associated with information retrieval for non-computer specialist users, and proposes a method for communicating in restricted English that uses knowledge of the entities involved, relationships between entities, and basic English language syntax and semantics to translate the user requests into formal queries. The proposed method includes an intelligent dictionary, syntax and semantic verifiers, and a formal query generator. In addition, the proposed system has a learning capability that can improve portability and performance. With the increasing demand for efficient human-machine communication, the significance of this thesis becomes apparent. As human resources become more valuable, software systems that will assist in improving the human-machine interface will be needed and research addressing new solutions will be of utmost importance. This thesis presents an initial design and implementation as a foundation for further research and development into the emerging field of natural language database query systems.

Dominick, Wayne D.↗
NASA NTRS1989

Intelligent control of robotic arm/hand systems for the NASA EVA retriever using neural networks

Adaptive/general learning algorithms using varying neural network models are considered for the intelligent control of robotic arm plus dextrous hand/manipulator systems. Results are summarized and discussed for the use of the Barto/Sutton/Anderson neuronlike, unsupervised learning controller as applied to the stabilization of an inverted pendulum on a cart system. Recommendations are made for the application of the controller and a kinematic analysis for trajectory planning to simple object retrieval (chase/approach and capture/grasp) scenarios in two dimensions.

Mclauchlan, Robert A.↗
NASA NTRS1989

Zonal Winds Between 25 and 120 Km Retrieved from Solar Occultation Spectra

Atmospheric winds at heights between 25 and 120 km have been retrieved with precisions of 5/ms from the Doppler shifts of atmospheric absorption lines measured from a satellite-borne instrument. Lines of the upsilon 3 CO2 and upsilon 2 H2O rotation-vibration bands caused by gases in the instrument allowed the instrumental frequency scale to be absolutely calibrated so that accurate relative speeds could be obtained. By comparing the positions of both sets of instrumental lines the calibration of the frequency scale was determined to be stable to a precision of less than 2 x 10(-5) cm during the course of each occultation. It was found that the instrumental resolution of 0.015 cm after apodization, the signal to noise ratio of about 100 and stable calibration allowed relative speeds to be determined to a precision of 5 ms or better by using small numbers of absorption lines between 1600 and 3200 cm. Absolute absorption line positions were simultaneously recovered to precisions of 5 x 10(-5) cm or better. The wind speed profiles determined from four sunset occultations and one sunrise occultation show remarkable similarities in the magnitudes and directions of the zonal wind velocities as functions of height. These wind profiles appear to be manifestations of atmospheric tides.

Vancleef, Garrett Warren↗
NASA NTRS1988

Identification and recovery of discontinuous synoptic features in satellite-retrieved brightness temperatures using a radiative transfer model

An attempt is made to recover and identify discontinuous synoptic features from satellite-retrieved brightness temperatures, with attention to near-discontinuities in temperature and moisture that are typically found in fronts and inversions. Efforts are made to ascertain whether the vectors of satellite channel brightness temperatures can be classified according to synoptic source, and whether those sources are amenable to quantification.

White, G. A., III↗
NASA NTRS1988

Thunderstorm ice induced brightness temperature depressions at 18, 37, and 92 GHz during Cohmex and their implications for satellite precipitation retrievals

Measurements of thunderstorm ice scattering at 18, 37, and 92 GHz, and with high spatial and temporal resolution from the Cooperative Huntsville Meterorlogical Experiment (Cohmex) are discussed. The Cohmex experiment consisted of ground-based, airborne, and satellite experiments in June and July, 1986. The rainfall rates from the experiment are compared with other measurements and the implications of the results for satellite precipitation retrievals are examined.

Hood, Robbie E.↗
NASA NTRS1989

Surface reflectance factor retrieval from Thematic Mapper data

Based on the absolute radiometric calibration of the TM and the use of a radiative transfer program for atmospheric correction, ground reflectances were retrieved for several fields of crops and bare soil in TM bands 1-4 for six TM scenes acquired over a 12-month period. These reflectances were compared to those measured using ground-based and low-altitude, aircraft-mounted radiometers. When, for four TM acquisitions, the comparison was made between areas that had been carefully selected for their high uniformity, the reflectance factors agreed to + or - 0.01 over the reflectance range 0.02-0.55. When the comparison was made for two of the above acquisitions and two others on different dates, for larger areas not carefully selected to be of uniform reflectance, the reflectance factors agreed to + or - 0.02 (1 sigma RMS), over same reflectance range.

Holm, Ronald G.↗
NASA NTRS1989

Evaluating atmospheric correction models for retrieving surface temperatures from the AVHRR over a tallgrass prairie

The effects of atmospheric attenuation on surface radiative temperatures obtained by the AVHRR over a tallgrass prairie area in the Flint Hills of Kansas are examined. Six atmospheric correction models developed primarily for sea-surface temperature studies are used to test their utility for retrieval of radiative temperatures over the land surface. An uncertainty of + or - 3.0 C was found for the AVHRR data, and used to evaluate the performance of a given model. When the difference between in situ and AVHRR surface temperatures was smaller than the uncertainty, the model was judged to be adequate. Among the six models evaluated, only the NOAA split-window model consistently adjusted the AVHRR surface temperatures within + or - 3.0 C of the in situ measurements.

Cooper, D. I.↗
NASA NTRS1989

Syncom 4 deploy, LDEF retrieval highlight 10-day Columbia flight

The objectives of Space Shuttle Mission STS-32 are described along with major flight activities, prelaunch and launch operations, trajectory sequence of events, and landing and post-landing operations. The primary objectives of STS-32 are the deployment of a Navy synchronous communications satellite (Syncom 4) and the retrieval of the Long Duration Exposure Facility (LDEF) launched from the Challenger in April 1984. Secondary STS-32 payloads include a protein crystal growth experiment, the Fluids Experiment Apparatus (FEA) for the investigation of microgravity materials processing, the Mesoscale Lighting Experiment, the Latitude-Longitude Locator Experiment, the Americal Flight Echocardiograph, and an experiment to investigate neurospora circadian rhythms in a microgravity environment.

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NASA NTRS1990

Smart hands for the EVA retriever

Dexterous, robotic hands are required for the extravehicular activity retriever (EVAR) system being developed by the NASA Johnson Space Center (JSC). These hands, as part of the EVAR system, must be able to grasp objects autonomously and securely which inadvertently separate from the Space Station. Development of the required hands was initiated in 1987. Outlined here are the hand development activities, including design considerations, progress to date, and future plans. Several types of dexterous hands that were evaluated, along with a proximity-sensing capability that was developed to initiate a reflexive, adaptive grasp, are described. The evaluations resulted in the design and fabrication of a 6-degree-of-freedom (DOF) hand that has two fingers and a thumb arranged in an anthropomorphic configuration. Finger joint force and position sensors are included in the design, as well as infrared proximity sensors which allow initiation of the grasp sequence when an object is detected within the grasp envelope.

Hess, Clifford W.↗
NASA NTRS1989

Multispectral retrieval of rainfall rates using the Special Sensor Microwave/Imager (SSM/I)

Collocated SSM/I and radar measurements are compared to model simulated radiances upwelling from precipitating clouds. A methodology maximizing the correlation between the radar rain rate estimates and surface rainfall amounts is presented, along with data sources and samples. Geolocation of both the satellite and radar data is assessed, and statistical rainfall-rate retrieval algorithms are analyzed. Regression analysis of collocated SSM/I brightness-temperature measurements and radar-derived rainfall rates show the potential of the SSM/I to provide 25-km resolution rain-rate estimates over land and ocean surfaces.

Olson, William S.↗
NASA NTRS1991

Video Image Communication And Retrieval - Updated

Video Image Communication and Retrieval (VICAR) package of computer programs is general-purpose image-processing software system. Intended for processing data from Jet Propulsion Laboratory's unmanned planetary spacecraft, now used in variety of other applications, including processing of biomedical images, cartography, studies of Earth resources, and geological exploration. Development of newest version of VICAR emphasizes standardized, easily-understood user interface, shield between user and host operating system, and comprehensive array of image-processing capabilities.

Wall, Ray J.↗
NASA NTRS1990

Mars penetrator sample retrieval system

Three University of Wisconsin-Madison space studies are discussed briefly. The Mars Penetrator Retrieval System, used to acquire and analyze soil samples from a region approximately 15 to 30 feet below the Martian surface, uses a drill bit with three cutting tips arranged in a radially terraced formation. A prototype was built and tested. The Mars Egg is a small surface analyzer that would be dropped on the surface of Mars from an orbiter and would analyze the gases present in the surface soil over a period of one Martian year to determine the diffusivity of the soil. The egg contains a gas chromatograph, radio transmitter, and the necessary power supplies. Also discussed is the design of a GeoShack, a manned or unmanned mini-space station in geosynchronous orbit, designed for the repair, attitude correction, and general upkeep of satellites in geosynchnonous orbit.

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