Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Data Association”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

A Survey of Autonomous Navigation Techniques Applicable to Lunar Surface Exploration

As humanity returns to the Moon, and more and more attention is being paid to lunar surface operations, there is a greater need than ever for methods of surface navigation. These could be methods of computer-assisted orienteering for astronauts exploring on foot during an Extra-Vehicular Activity (EVA), or methods of solving the Lost-on-the-Moon problem to initialize a crewed or autonomous rover’s state estimate. It may also be necessary to process navigation data associated with surface samples or other surface operations a posteriori to better understand where that analysis occurred. Autonomous rover operation will also require Hazard Detection and Avoidance (HDA) and terrain-aware pathfinding. While navigation on the surface of the Moon will likely rely on Earth-based assets such as the Deep Space Network (DSN) or communication with other spacecraft (e.g., LunaNet, LCRNS, pre-deployed moon beacons, a nearby lander) it may be necessary to navigate in a loss-of-communication scenario. This paper analyzes the methods of surface navigation used on other celestial bodies, such as those used during the Apollo missions and autonomous exploration of Mars, as well as novel methods which have been studied but not yet implemented which may prove useful. It is shown that the navigator has myriad options when processing data from an Inertial Measurement Unit (IMU), a star tracker, (rover) wheel encoders, optical cameras, and LIght Detection and Ranging (LIDAR) sensors. The intention of this paper is to provide a broad overview of what has been done and what could be done, to aid those designing vehicles and/or missions to the lunar surface.

Paul McKee↗
NASA NTRS2016

Cloud Motion in the GOCI COMS Ocean Colour Data

The Geostationary Ocean Colour Imager (GOCI) instrument, on Koreas Communications, Oceans, and Meteorological Satellite (COMS), can produce a spectral artefact arising from the motion of clouds the cloud is spatially shifted and the amount of shift varies by spectral band. The length of time it takes to acquire all eight GOCI bands for a given slot (portion of a scene) is sucient to require that cloud motion be taken into account to fully mask or correct the eects of clouds in all bands. Inter-band correlations can be used to measure the amount of cloud shift, which can then be used to adjust the cloud mask so that the union of all shifted masks can act as a mask for all bands. This approach reduces the amount of masking required versus a simple expansion of the mask in all directions away from clouds. Cloud motion can also aect regions with unidentied clouds thin or fractional clouds that evade the cloud identication process yielding degraded quality in retrieved ocean colour parameters. Areas with moving and unidentied clouds require more elaborate masking algo-rithms to remove these degraded retrievals. Correction for the eects of moving fractional clouds may also be possible. The cloud shift information can be used to determine cloud motion and thus wind at the cloud levels on sub-minute timescales. The benecial and negative eects of moving clouds should be con-sidered for any ocean colour instrument design and associated data processing plans.

Robinson, Wayne D.↗
NASA NTRS1972

Analysis of radiation and meteoroid satellite data

The data obtained in earth orbit by the Radiation and Meteoroid Satellite (RMS) were interpreted and reduced to a form which will be usable by future space experimenters. The required tasks are detailed. Computer programs were written which lifted the raw data and associated emphemeris data from the GFE magnetic tapes. The engineering data was then used to evaluate the performance of the spacecraft and the experiments. The radiation data was used to prepare flux, spectral, and dose maps of the South Atlantic magnetic anomaly where possible. The meteoroid data was used to determine a rough estimate of the meteoroid flux and in general evaluate the performance of the thin-film meteoroid sensors. The degree of success of the RMS mission was evaluated in light of the separation anomaly which occurred between RMS and OFO during launch.

Farmer, B. J.↗
NASA NTRS1972

Prediction and measurement of heat transfer rates for the shock-induced unsteady laminar boundary layer on a flat plate

The unsteady laminar boundary layer induced by the flow-initiating shock wave passing over a flat plate mounted in a shock tube was theoretically and experimentally studied in terms of heat transfer rates to the plate for shock speeds ranging from 1.695 to 7.34 km/sec. The theory presented by Cook and Chapman for the shock-induced unsteady boundary layer on a plate is reviewed with emphasis on unsteady heat transfer. A method of measuring time-dependent heat-transfer rates using thin-film heat-flux gages and an associated data reduction technique are outlined in detail. Particular consideration is given to heat-flux measurement in short-duration ionized shocktube flows. Experimental unsteady plate heat transfer rates obtained in both air and nitrogen using thin-film heat-flux gages generally agree well with theoretical predictions. The experimental results indicate that the theory continues to predict the unsteady boundary layer behavior after the shock wave leaves the trailing edge of the plate even though the theory is strictly applicable only for the time interval in which the shock remains on the plate.

Cook, W. J.↗
NASA NTRS1973

CIT photoheliograph functional verification unit test program

Tests of the 2/3-meter photoheliograph functional verification unit FVU were performed with the FVU installed in its Big Bear Solar Observatory vacuum chamber. Interferometric tests were run both in Newtonian (f/3.85) and Gregorian (f/50) configurations. Tests were run in both configurations with optical axis horizontal, vertical, and at 45 deg to attempt to determine any gravity effects on the system. Gravity effects, if present, were masked by scatter in the data associated with the system wavefront error of 0.16 lambda rms ( = 6328A) apparently due to problems in the primary mirror. Tests showed that the redesigned secondary mirror assembly works well.

Source record↗
NASA NTRS1975

Structural response of a fiber composite compressor fan blade airfoil

A theoretical investigation was performed to determine the structural response of a fiber composite airfoil typical of those encountered in high-tip speed compressor fan blades when subjected to load conditions anticipated in such applications. The analysis method consisted of composite mechanics embedded in pre- and post-processors coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, and centrifugal. Root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions were investigated. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. The core-shell concept for composite blades is an inefficient design and is sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for the analysis, and to provide quantitative data associated with the various responses which can be helpful in designing composite blades.

Chamis, C. C.↗
NASA NTRS1975

Hypermatrix scheme for finite element systems on CDC STAR-100 computer

A study is made of the adaptation of the hypermatrix (block matrix) scheme for solving large systems of finite element equations to the CDC STAR-100 computer. Discussion is focused on the organization of the hypermatrix computation using Cholesky decomposition and the mode of storage of the different submatrices to take advantage of the STAR pipeline (streaming) capability. Consideration is also given to the associated data handling problems and the means of balancing the I/Q and cpu times in the solution process. Numerical examples are presented showing anticipated gain in cpu speed over the CDC 6600 to be obtained by using the proposed algorithms on the STAR computer.

Noor, A. K.↗
NASA NTRS1977

The navigation system of the JPL robot

The control structure of the JPL research robot and the operations of the navigation subsystem are discussed. The robot functions as a network of interacting concurrent processes distributed among several computers and coordinated by a central executive. The results of scene analysis are used to create a segmented terrain model in which surface regions are classified by traversibility. The model is used by a path planning algorithm, PATH, which uses tree search methods to find the optimal path to a goal. In PATH, the search space is defined dynamically as a consequence of node testing. Maze-solving and the use of an associative data base for context dependent node generation are also discussed. Execution of a planned path is accomplished by a feedback guidance process with automatic error recovery.

Thompson, A. M.↗
NASA NTRS1977

Snow parameters from Nimbus-6 electrically scanned microwave radiometer

Two sites in Canada were selected for detailed analysis of the ESMR-6/ snow relationships. Data were analyzed for February 1976 for site 1 and January, February and March 1976 for site 2. Snowpack water equivalents were less than 4.5 inches for site 1 and, depending on the month, were between 2.9 and 14.5 inches for site 2. A statistically significant relationship was found between ESMR-6 measurements and snowpack water equivalents for the Site 2 February and March data. Associated analysis findings presented are the effects of random measurement errors, snow site physiolography, and weather conditions on the ESMR-6/snow relationship.

Abrams, G.↗
NASA NTRS1978

GEOS-3 C-Band radar investigations

The absolute accuracy of instrumentation radar systems, refined methods of calibrating these systems, and the techniques employed in processing the associated data. A world-wide network of C-Band instrumentation radars augmented by lasers and other tracking instrumentation systems were used. The NASA WFC AN/FPQ-6 instrumentation radar and the AN/FPS-16 instrumentation radar also located at NASA WFC were the primary instruments used in the accuracy and calibration evaluations. The results achieved at WFC were then disseminated to other Ranges where they were verified, augmented and used as part of routine operations.

Dempsey, D. J.↗
NASA NTRS1978

Associative programming language and virtual associative access manager

APL provides convenient associative data manipulation functions in a high level language. Six statements were added to PL/1 via a preprocessor: CREATE, INSERT, FIND, FOR EACH, REMOVE, and DELETE. They allow complete control of all data base operations. During execution, data base management programs perform the functions required to support the APL language. VAAM is the data base management system designed to support the APL language. APL/VAAM is used by CADANCE, an interactive graphic computer system. VAAM is designed to support heavily referenced files. Virtual memory files, which utilize the paging mechanism of the operating system, are used. VAAM supports a full network data structure. The two basic blocks in a VAAM file are entities and sets. Entities are the basic information element and correspond to PL/1 based structures defined by the user. Sets contain the relationship information and are implemented as arrays.

Carol Price↗
NASA NTRS1978

The Earth Radiation Budget Satellite System

The scientific objectives of an Earth Radiation Budget Satellite System (ERBSS) are discussed along with the associated data analysis methods, mission analysis, and the instrument systems. High resolution data on the scale of about 250 km over the entire globe are essential to gain insight into such features as the development of sea-surface temperature anomalies, radiation effects of ice and snow cover on the atmospheric circulation, albedo variation in the desert-vegetation boundaries, and major long-period circulation phenomena. The ERBSS experiment is also viewed as a precursor of an operational satellite system for monitoring the earth's radiation budget. Various numbers of satellites and orbit inclinations have been analyzed to define the satellite combination which provides sufficient coverage of the earth for spatial and temporal radiation sampling.

Woerner, C. V.↗
NASA NTRS1978

Information systems

Space-derived information is the principal product of our civilian space program. Associated data from earth-orbital and planetary spacecraft will exceed the equivalent of some 500 television pictures per second during the 1980's. Cost-effective management of this data flood requires a new look at NASA's overall information systems. Advanced technologies being pursued by industry and NASA could provide order-of-magnitude reductions in data-handling costs and times to permit a massive increase in the use of space-acquired data for both individual and national needs. This paper discusses attendant thrusts in efficient data acquisition, instrument pointing, real-time data management, and low-cost data distribution. Current and planned technology activities in these areas and their anticipated impact on future space missions are described.

Kurzhals, P. R.↗
NASA NTRS1979

HEAO 1 scanning modulation collimator discovery of an extended X-ray source at Cygnus A

The HEAO 1 modulation-collimator data associate the X-ray emission from the Cygnus A region (4U 1957 + 40) with a small area including the radio galaxy. The source appears to be extended, with a size of about 2 arcmin; it may have a complex geometry. Any point-source component must have a flux no greater than 1.3 UFU. A lower limit of 1 microgauss is placed on the magnetic field in the radio lobes, based on the upper limit on the X-ray flux due to inverse Compton scattering of radio electrons on the 2.7-K microwave background radiation. The X-ray emission is more likely due to driven accretion of the intercluster gas onto the giant cD radio galaxy. Therefore this source appears to be similar to the Virgo and Perseus clusters. The density derived for the X-ray-emitting gas is too small for its thermal pressure to confine the radio source.

Fabbiano, G.↗
NASA NTRS1980

Argon/UF6 plasma experiments: UF6 regeneration and product analysis

An experimental and analytical investigation was conducted to aid in developing some of the technology necessary for designing a self-critical fissioning uranium plasma core reactors (PCR). This technology is applicable to gaseous uranium hexafluoride nuclear-pumped laser systems. The principal equipment used included 1.2 MW RF induction heater, a d.c. plasma torch, a uranium tetrafluoride feeder system, and batch-type fluorine/UF6 regeneration systems. Overall objectives were to continue to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure, gaseous UF6; and to continue development of complementary diagnostic instrumentation and measurement techniques to characterize the effluent exhaust gases and residue deposited on the test chamber and exhaust system components. Specific objectives include: a development of a batch-type UF6 regeneration system employing pure high-temperature fluorine; development of a ruggedized time-of-flight mass spectrometer and associated data acquisition system capable of making on-line concentration measurements of the volatile effluent exhaust gas species in a high RF environment and corrosive environment of UF6 and related halide compounds.

Roman, W. C.↗