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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

A new method of measuring radio source parameters of a partially polarized distributed source from spacecraft observations

An experimental system is analyzed which is designed to determine the angular and polarization properties of low frequency radio sources from measurements made on a spinning spacecraft. The system has been optimized to provide high accuracies for sources at high as well as low elevation angles. Theoretical expressions are derived for the response of this system to a partially polarized point source. Integrations are then carried out to get the system response to a uniform circular distributed source. Data processing techniques are derived so that computer simulations can be carried out to investigate the accuracy of this technique. It is shown that using 24 measurements of a partially polarized source (with Q = U = V = 0.5), taken in one spacecraft rotation, the resulting rms errors in angular position are less than one degree and the errors in determining the Stokes parameters are generally 1-10% for a wide range of source elevations.

Manning, R.↗
NASA NTRS1987

Experimental determination of the stable-trim attitudes of two proposed, general-purpose, heat-source modules

Ballistic range tests have been conducted to determine the aerodynamically stable trim attitudes of two proposed general-purpose heat-source module configurations. Tests were conducted at speeds of 4.6 km/sec for the concept module, and at both 4.6 km/sec and 1.4 km/sec for the MOD II. Test results indicated that both configurations were stable when launched in the face-on attitude. When launched in the side-on attitude, the MOD II configuration was found to be stable, while tests of the concept module did not give definitive results.

Kruse, Robert L.↗
NASA NTRS1985

Satellite laser ranging - Current status and future prospects

The characteristics and capabilities of instruments and operational techniques in the field of satellite laser ranging (SLR) are discussed. Following a brief introduction to the basic concept of SLR, a developmental history of each of the major components of an SLR hardware is given, including the laser transmitter, photomultiplier, discriminator, and time interval unit. The sources of range error in each of the devices are examined, and techniques for reducing error are described. A description of current SLR hardware is summarized using samples of actual satellite data obtained in 1981, which show that orbital fits with a 1.5 single shot rms and normal point rms error of less than 3 mm with 1-6 percent data entering. The development of even more precise measurement techniques in the future with the advent of the Starlette and LAGEOS II SLR system is also discussed.

Degnan, J. J.↗
NASA NTRS2006

Development of Standardized Lunar Regolith Simulant Materials

Lunar exploration requires scientific and engineering studies using standardized testing procedures that ultimately support flight certification of technologies and hardware. It is necessary to anticipate the range of source materials and environmental constraints that are expected on the Moon and Mars, and to evaluate in-situ resource utilization (ISRU) coupled with testing and development. We describe here the development of standardized lunar regolith simulant (SLRS) materials that are traceable inter-laboratory standards for testing and technology development. These SLRS materials must simulate the lunar regolith in terms of physical, chemical, and mineralogical properties. A summary of these issues is contained in the 2005 Workshop on Lunar Regolith Simulant Materials [l]. Lunar mare basalt simulants MLS-1 and JSC-1 were developed in the late 1980s. MLS-1 approximates an Apollo 11 high-Ti basalt, and was produced by milling of a holocrystalline, coarse-grained intrusive gabbro (Fig. 1). JSC-1 approximates an Apollo 14 basalt with a relatively low-Ti content, and was obtained from a glassy volcanic ash (Fig. 2). Supplies of MLS-1 and JSC-1 have been exhausted and these materials are no longer available. No highland anorthosite simulant was previously developed. Upcoming lunar polar missions thus require the identification, assessment, and development of both mare and highland simulants. A lunar regolith simulant is manufactured from terrestrial components for the purpose of simulating the physical and chemical properties of the lunar regolith. Significant challenges exist in the identification of appropriate terrestrial source materials. Lunar materials formed under comparatively reducing conditions in the absence of water, and were modified by meteorite impact events. Terrestrial materials formed under more oxidizing conditions with significantly greater access to water, and were modified by a wide range of weathering processes. The composition space of lunar materials can be modeled by mixing programs utilizing a low-Ti basalt, ilmenite, KREEP component, high-Ca anorthosite, and meteoritic components. This approach has been used for genetic studies of lunar samples via chemical and modal analysis. A reduced composition space may be appropriate for simulant development, but it is necessary to determine the controlling properties that affect the physical, chemical and mineralogical components of the simulant.

Carpenter, P.↗
NASA NTRS2009

Production of NOx by Lightning and its Effects on Atmospheric Chemistry

Production of NO(x) by lightning remains the NO(x) source with the greatest uncertainty. Current estimates of the global source strength range over a factor of four (from 2 to 8 TgN/year). Ongoing efforts to reduce this uncertainty through field programs, cloud-resolved modeling, global modeling, and satellite data analysis will be described in this seminar. Representation of the lightning source in global or regional chemical transport models requires three types of information: the distribution of lightning flashes as a function of time and space, the production of NO(x) per flash, and the effective vertical distribution of the lightning-injected NO(x). Methods of specifying these items in a model will be discussed. For example, the current method of specifying flash rates in NASA's Global Modeling Initiative (GMI) chemical transport model will be discussed, as well as work underway in developing algorithms for use in the regional models CMAQ and WRF-Chem. A number of methods have been employed to estimate either production per lightning flash or the production per unit flash length. Such estimates derived from cloud-resolved chemistry simulations and from satellite NO2 retrievals will be presented as well as the methodologies employed. Cloud-resolved model output has also been used in developing vertical profiles of lightning NO(x) for use in global models. Effects of lightning NO(x) on O3 and HO(x) distributions will be illustrated regionally and globally.

Pickering, Kenneth E.↗
NASA NTRS2005

Three-Dimensional Application of DAMAS Methodology for Aeroacoustic Noise Source Definition

At the 2004 AIAA/CEAS Aeroacoustic Conference, a breakthrough in acoustic microphone array technology was reported by the authors. A Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) was developed which decouples the array design and processing influence from the noise being measured, using a simple and robust algorithm. For several prior airframe noise studies, it was shown to permit an unambiguous and accurate determination of acoustic source position and strength. As a follow-on effort, this paper examines the technique for three-dimensional (3D) applications. First, the beamforming ability for arrays, of different size and design, to focus longitudinally and laterally is examined for a range of source positions and frequency. Advantage is found for larger array designs with higher density microphone distributions towards the center. After defining a 3D grid generalized with respect to the array s beamforming characteristics, DAMAS is employed in simulated and experimental noise test cases. It is found that spatial resolution is much less sharp in the longitudinal direction in front of the array compared to side-to-side lateral resolution. 3D DAMAS becomes useful for sufficiently large arrays at sufficiently high frequency. But, such can be a challenge to computational capabilities, with regard to the required expanse and number of grid points. Also, larger arrays can strain basic physical modeling assumptions that DAMAS and all traditional array methodologies use. An important experimental result is that turbulent shear layers can negatively impact attainable beamforming resolution. Still, the usefulness of 3D DAMAS is demonstrated by the measurement of landing gear noise source distributions in a difficult hard-wall wind tunnel environment.

Brooks, Thomas F.↗
DOE OSTI2020

Radioactive Source Localization via Bayesian Particle Filter

In the event of a misplaced radioactive source or other emergency situation, measuring a radiation field, mapping its distribution, and determining a source location are essential tasks to ameliorating the situation. However, radiation fields may be extremely hazardous to human surveyors and minimizing received radiation doses is just as essential. Robots appear to be a potential solution to these problems. Beyond simply measuring radiation, the robot's computer processing capabilities offer a way to apply complex data analysis methods to radiation measurements in real-time. Methods which predict likely source locations can then feed this information into other processes, potentially improving path planning and enabling more efficient measurements. Given a robot mounted with a gamma-ray detector, can we: develop a methodology to account for detector performance across a wide range of source angles, distances, and photon energies? operate an autonomously navigating robot to effectively survey and characterize an area of interest? implement a data analysis method, conventionally used in measurements of motion, for source localization purposes? An open-source TurtleBot 3 robot, running Robot Operating System (ROS) on Ubuntu 16.04 LTS, was fitted with a Kromek GR1{sup R} Cadmium Zinc Telluride (CZT) solid-state gamma-ray detector. As a part of ROS, the packages OpenSlam, gmapping, and amcl were used to perform Simultaneous Localization and Mapping (SLAM), determining the robot's position and mapping the surrounding area. Data was acquired via Lidar mounted on top the TurtleBot 3. Detector Calibration Fit: The equation was fit to 365 counts of various energies, distances, and angles. A MATLAB{sup R} program was written to simulate measurements taken a robot on a random walk, with count data and positions discretized into finite element pixels. Using this program, a sample of 100 runs was performed on a map with a simulated source at the center, with a total of 200 of 2 pixels each. Similarly, multiple runs of the filter were performed on recorded robot measurement data. In both simulation and real tests, when corrected for errors (particles placed outside of bounds or on the robot, and simulation-specific errors), corresponding t-tests of predicted x and y-coordinates were within a 95% confidence interval of the actual position. For the real trial, these positions are slightly skewed right in the x-axis as the robot remained mainly to the left side of the source within the sample area. These simulations demonstrate potential validity for the usage of a particle filter as method of radioactive source localization. In the future, true real-time implementation and data fusion may further augment the performance of the robot to localize lost sources. Additionally, identification of multiple sources, determination of source types, and usage of a collimator are areas to potentially be explored.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Hydrothermal Liquid Recovery of Rare Earth Elements and Critical Materials

This project demonstrated the technical viability of using tunable hydrothermal liquid (HTL) solutions to recover valuable minerals from a range of source materials. The effort focused upon rare earth elements (REE) and other minerals critical to the industrial security of the United States. This effort demonstrated, for the first time, that s, supercritical water (SCW) in particular, can: Extract critical and valuable minerals from a range of matrices ranging from rock ore to biomass; The process can be used to recover a wide range of minerals; This novel extraction chemistry can be cheap, simple, and nontoxic/”green”: The chemical extraction uses water, the cheapest industrial acid (sulfuric), and simple salts (i.e. sodium sulfate). However, other acids, salts, and additives could be used as appropriate. This Laboratory Directed Research and Development (LDRD) project identified that the process is complex with many interacting factors, but the benefits are significant if the complexities can be resolved. Challenges remain in the development of this technology and are described in this report. However, the results are positive, and commercial partners have already expressed interest. In summary, a novel, green, inexpensive mineral extraction process has been developed and demonstrated in a small batch reactor system. The effort provided information for an invention disclosure, proposal to DOE, and will support future business development efforts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1993

On the optimality of a universal noiseless coder

Rice developed a universal noiseless coding structure that provides efficient performance over an extremely broad range of source entropy. This is accomplished by adaptively selecting the best of several easily implemented variable length coding algorithms. Variations of such noiseless coders have been used in many NASA applications. Custom VLSI coder and decoder modules capable of processing over 50 million samples per second have been fabricated and tested. In this study, the first of the code options used in this module development is shown to be equivalent to a class of Huffman code under the Humblet condition, for source symbol sets having a Laplacian distribution. Except for the default option, other options are shown to be equivalent to the Huffman codes of a modified Laplacian symbol set, at specified symbol entropy values. Simulation results are obtained on actual aerial imagery over a wide entropy range, and they confirm the optimality of the scheme. Comparison with other known techniques are performed on several widely used images and the results further validate the coder's optimality.

Yeh, Pen-Shu↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 4E: Right ascension range 08h 00m to 11h 59m

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images, The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentaion describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers, and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 5E: Right ascension range 12h 00m to 15h 59m

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics, which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers, and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 6E: Right ascension range 16h 00m to 19h 59m

The Einstein Observatory (HEAO-2 launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics, which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers, and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 7E: Right ascension range 20h 00m to 23h 59m

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers, and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 2E: Right ascension range 00h 00m to 03h 59m

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1993

The Einstein Observatory catalog of IPC x ray sources. Volume 3E: Right ascension range 04h 00m to 07h 59m

The Einstein Observatory (HEAO-2, launched November 13, 1978) achieved radically improved sensitivity over previous x-ray missions through the use of focusing optics which simultaneously afforded greatly reduced background and produced true images. During its 2.5-yr mission, the Einstein X-Ray Telescope was pointed toward some 5,000 celestial targets, most of which were detected, and discovered several thousand additional 'serendipitous' sources in the observed fields. This catalog contains contour diagrams and source data, obtained with the imaging proportional counter in the 0.16 to 3.5 keV energy band, and describes methods for recovering upper limits for any sky position within the observed images. The main catalog consists of six volumes (numbered 2 through 7) of right ascension ordered pages, each containing data for one observation. Along with the primary documentation describing how the catalog was constructed, volume 1 contains a complete source list, results for merged fields, a reference system to published papers and data useful for calculating upper limits and fluxes.

Harris, D. E.↗
NASA NTRS1988

The terrestrial plasma source - A new perspective in solar-terrestrial processes from Dynamics Explorer

The geospace environment has been viewed as a mixing bowl for plasmas of both solar and terrestrial origin. The present perspective on the nature of the supply mechanisms has undergone a radical evolution over the past decade, particularly during the five years of the Dynamics Explorer mission. During this period, the terrestrial source has increased in importance in both magnitude and character of ionospheric outflow. These outflows include the classical polar wind, the cleft ion fountain, the auroral ion fountain, and the polar cap. The earth can be envisioned as a multifaceted fountain which ejects particles from different spatial locations spread around the globe. These particles exhibit a range of masses from 1 to 32 amu and a range of energies from 1 eV to 10 keV. The total flux of this ionospheric outflow is very large: adequate to supply the entire magnetospheric particle population. And the implications of the outflow are significant across a broad spectrum of solar-terrestrial processes ranging from sources of magnetospheric plasmas, to influences on ionospheric density and temperature structure, to energy transfer in phenomena such as stable auroral red arcs. The Dynamics Explorer mission has made a major contribution in the characterization of the terrestrial plasma source.

Chappell, Charles R.↗
NASA NTRS1993

The terrestrial gravitational wave environment from known sources

The objective of this project was to produce a gravitational wave spectral line list of all known binary stars producing expected strain amplitudes at Earth in excess of h = 10 (exp -21), or gravitational wave fluxes in excess of F = 10 (exp -12) erg cm(exp -2) s(exp -1). These strain and flux limits lie above the anticipated detection thresholds for space-borne laser interferometers capable of detecting gravitational radiation in the 10 micron Hz to 1 Hz frequency range. The source list was intended to provide frequency (including each harmonic), amplitude and phase (for each polarization and harmonic), and celestial coordinates for each system, lacking only the orientation of the principal polarization axis with respect to the pole of the coordinate system, and the sign of the source phase and frequency (or, equivalently, of the sense of rotation of the strain tensor with time) from providing a complete source description. Such a spectral line list would lay essential groundwork for high-sensitivity, low-frequency searches for gravitational radiation.

Webbink, Ronald F.↗
NASA NTRS2010

Validation of a New Procedure for Impedance Eduction in Flow

A new impedance eduction procedure is validated by comparing the educed impedance spectrum to that of an older but well-tested eduction procedure. The older procedure requires the installation of a microphone array in the liner test section but the new procedure removes this requirement. A 12.7-mm stainless steel plate and a conventional liner consisting of a perforated plate bonded to a honeycomb core are tested. Test data is acquired from a grazing flow, impedance tube facility for a range of source frequencies and mean flow Mach numbers for which only plane waves are cut on. For the stainless steel plate, the educed admittance spectrum using the new procedure shows an improvement over that of the old procedure. This improvement shows up primarily in the educed conductance spectrum. Both eduction procedures show discrepancies in educed admittance in the mid-frequency range. Indications are that this discrepancy is triggered by an inconsistency between the measured eduction data (that contains boundary layer effects) and the two eduction models (for which the boundary layer is neglected). For the conventional liner, both eduction procedures are in very good agreement with each other. Small discrepancies occur for one or two frequencies in the mid-frequency range and for frequencies beyond the cut on frequency of higher-order duct modes. This discrepancy in the midfrequency range occurs because an automated optimizer is used to educe the impedance and the objective function used by the optimizer is extremely flat and therefore sensitive to initial starting values. The discrepancies at frequencies beyond the cut on frequency of higher order duct modes are due to the assumption of only plane waves in the impedance eduction model, although higher order modes are propagating in the impedance tube facility.

Watson, W. R.↗