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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Fiber Scanning Array for 3 Dimensional Topographic Imaging

We report on the design and development of a fiber optic scanning 3-D LIDAR employing a switched fiber array. This design distributes ns length laser pulses over a sample field, collects the return pulses, and assembles them into a 3-D image. This instrument is a reduced size version consisting of 35 beams, and will serve as a proof-of-principle demonstration for a planned 1000 beam instrument for Earth and planetary topographical missions.

3D↗
NASA NTRS1995

Legacy: General Aviation Highlights from 8 Decades of NACA/NASA Research

Legacy includes the bibliographic citations and full text images of 179 NACA (National Advisory Committee for Aeronautics) and NASA (National Aeronautics and Space Administration) reports of interest to the general aviation (GA) community. The majority of titles included in this collection were recommended by the GA community in response to an Advanced General Aviation Transport Experiments (AGATE) survey conducted in January 1995. Searching and browsing of the collection is supported using all elements of the bibliographic record. A complete scanned image of each report is provided for viewing and printing. This 'first volume' of Legacy is a prototype product that will serve as a proof-of-concept trial for distributing information via CD-ROM to members of AGATE and others. The CD-ROM may be operated on Mac (6.0.5 or higher), Windows (3.1 or higher), or DOS (3.0 or higher) platforms.

Adkins, Susan L.↗
NASA NTRS1995

Hologic QDR 2000 whole-body scans: a comparison of three combinations of scan modes and analysis software

This study reports on the short-term in vivo precision and absolute measurements of three combinations of whole-body scan modes and analysis software using a Hologic QDR 2000 dual-energy X-ray densitometer. A group of 21 normal, healthy volunteers (11 male and 10 female) were scanned six times, receiving one pencil-beam and one array whole-body scan on three occasions approximately 1 week apart. The following combinations of scan modes and analysis software were used: pencil-beam scans analyzed with Hologic's standard whole-body software (PB scans); the same pencil-beam analyzed with Hologic's newer "enhanced" software (EPB scans); and array scans analyzed with the enhanced software (EA scans). Precision values (% coefficient of variation, %CV) were calculated for whole-body and regional bone mineral content (BMC), bone mineral density (BMD), fat mass, lean mass, %fat and total mass. In general, there was no significant difference among the three scan types with respect to short-term precision of BMD and only slight differences in the precision of BMC. Precision of BMC and BMD for all three scan types was excellent: < 1% CV for whole-body values, with most regional values in the 1%-2% range. Pencil-beam scans demonstrated significantly better soft tissue precision than did array scans. Precision errors for whole-body lean mass were: 0.9% (PB), 1.1% (EPB) and 1.9% (EA). Precision errors for whole-body fat mass were: 1.7% (PB), 2.4% (EPB) and 5.6% (EA). EPB precision errors were slightly higher than PB precision errors for lean, fat and %fat measurements of all regions except the head, although these differences were significant only for the fat and % fat of the arms and legs. In addition EPB precision values exhibited greater individual variability than PB precision values. Finally, absolute values of bone and soft tissue were compared among the three combinations of scan and analysis modes. BMC, BMD, fat mass, %fat and lean mass were significantly different between PB scans and either of the EPB or EA scans. Differences were as large as 20%-25% for certain regional fat and BMD measurements. Additional work may be needed to examine the relative accuracy of the scan mode/software combinations and to identify reasons for the differences in soft tissue precision with the array whole-body scan mode.

NASA Discipline Musculoskeletal↗
DOE OSTI2024

Interplay between Topological States and Rashba States as Manifested on Surface Steps at Room Temperature

The unique spin texture of quantum states in topological materials underpins many proposed spintronic applications. However, realizations of such great potential are stymied by perturbations, such as temperature and local fields imposed by impurities and defects, that can render a promising quantum state uncontrollable. Here, in this study, we report room-temperature scanning tunneling microscopy/spectroscopy observation of interaction between Rashba states and topological surface states, which manifests local electronic structure along step edges controllable by the layer thickness of thin films. The first-principles theoretical calculation elucidates the robust Rashba states coexisting with topological surface states along the surface steps with characteristic spin textures in momentum space. Furthermore, the Rashba edge states can be switched off by reducing the thickness of a topological insulator Bi 2 Se 3 to bolster their interaction with the hybridized topological surface states. The study unveils a manipulating mechanism of the spin textures at room temperature, reinforcing the necessity of thin film technology in controlling the quantum states.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Sleepy Hollow Reagan Unit 86A Well Data

Computed tomography data described in the technical report series "Computed Tomography Scanning and Geophysical Measurements of the Integrated Mid-Continent Stacked Carbon Storage Hub Sleepy Hollow Reagan Unit 86A Well" by Thomas Paronish; Mathias Pohl; Alexis Parker; Rhiannon Schmitt; Johnathan Moore; Richard Spaulding; Igor Haljasmaa; Dustin Crandall; Valarie Smith; Andrew Duguid; and R. M. Joeckel

AS↗
NASA NTRS1974

Analysis of the Vertical Temperature Profile Radiometer (VTPR) radiometric problem

Variations in bias radiation, on the detector as a function of scan mirror position, are reported for the VTPR instruments presently in orbit. Tests in the laboratory show that this bias radiation disappears when optical baffles are added. A detailed analysis explains quantitatively the observed bias variation which is due to the extraneous field-of-view of the detector, and the variation in magnitude of the far field-of-view solid angle as a function of mirror position.

Goldberg, I. L.↗
NASA NTRS1974

Skylab S-191 spectrometer single spectral scan analysis program

Documentation and user information for the S-191 single spectral scan analysis program are reported. A breakdown of the computational algorithms is supplied, followed by the program listing and examples of sample output. A copy of the flow chart which describes the driver routine in the body of the main program segment is included.

Downes, E. L.↗
NASA NTRS1975

Interstellar K I and Na I absorption lines near rho Ophiuchi

Results are reported for photoelectric interferometric scans of the interstellar K I (7699 A) and Na I D1 absorption lines toward rho Oph AB and omicron Sco in the complex of dark clouds near rho Oph. The scans are found to reveal a well-marked line multiplicity toward both stars. It is shown that the resolved components of the line profiles can provide a natural explanation for the difference between the radial velocity of the strongest atomic lines of Na I and Ca II and that of the much weaker molecular lines of CH(+), CH, and CN that was previously observed toward rho Oph. The less saturated 7699-A lines toward both stars yield K I column densities roughly consistent with the calculated interstellar reddening.

Hobbs, L. M.↗
NASA NTRS1979

HEAO-1 observations of AM Herculis between 0.1 and 3 keV

Results are reported for HEAO A2 scanning observations of AM Her in the energy range from 0.1 to 3 keV. A light curve of AM Her is plotted, a typical flux of 8 x 10 to the -10th erg/sq cm-sec in the 0.15-0.5-keV range at X-ray maximum is estimated, and no pronounced spectral variation with phase is detected. It is found that both a 0.025-keV blackbody spectrum and an exponential spectrum with an energy-dependent Gaunt factor provide an acceptable fit to the data. It is concluded that the spectrum of the radiation from the plasma at the surface of the strongly magnetic and relatively massive white dwarf in AM Her consists of three components: (1) a high-temperature (about 100 million to 1 billion K) component produced by electron-ion bremsstrahlung in the hot postshock plasma; (2) a blackbody component of about 100,000 to 1 million K produced by the heated surface of the white dwarf; and (3) a still softer component produced by optically thick electron cyclotron emission in the postshock region.

Tuohy, I. R.↗
NASA NTRS1992

Detailed examination of LDEF's frame and the A0178 thermal blankets by the meteoroid and debris special investigations group

A responsibility of the group is to define the hypervelocity particle environment encountered by LDEF during its stay in low Earth orbit. LDEF's 6061-T6 aluminum frame and the 'Teflon silver-inconel paint' thermal blankets represent large surface areas that were widely distributed around the spacecraft. The results are reported of high resolution scans of approx. 0.36 and approx. 0.31 sq m for the intercostals and thermal blankets, respectively. The findings are in qualitative agreement with existing model predictions that suggest high differential bombardment histories for surfaces pointing into specific directions relative to the velocity vector of a non-spinning platform in LEO. The production rate for craters greater than or = 50 microns in diameter in aluminum and penetration holes greater than or = 100 microns in diameter in thin foil materials differ by more than a factor of 10 between forward and rearward facing surfaces. These are substantial differences that must be considered during the design of future long duration space platforms in LEO.

See, Thomas H.↗
NASA NTRS1994

MODIS Technical Report Series. Volume 4: MODIS data access user's guide: Scan cube format

The software described in this document provides I/O functions to be used with Moderate Resolution Spectroradiometer (MODIS) level 1 and 2 data, and could be easily extended to other data sources. This data is in a scan cube data format: a 3-dimensional ragged array containing multiple bands which have resolutions ranging from 250 to 1000 meters. The complexity of the data structure is handled internally by the library. The I/O calls allow the user to access any pixel in any band through 'C' structure syntax. The high MODIS data volume (approaching half a terabyte per day) has been a driving factor in the library design. To avoid recopying data for user access, all I/O is performed through dynamic 'C' pointer manipulation. This manual contains background material on MODIS, several coding examples of library usage, in-depth discussions of each function, reference 'man' type pages, and several appendices with details of the included files used to customize a user's data product for use with the library.

Kalb, Virginia L.↗
NASA NTRS2009

A Data Matrix Method for Improving the Quantification of Element Percentages of SEM/EDX Analysis

A simple 2D M N matrix involving sample preparation enables the microanalyst to peer below the noise floor of element percentages reported by the SEM/EDX (scanning electron microscopy/ energy dispersive x-ray) analysis, thus yielding more meaningful data. Using the example of a 2 3 sample set, there are M = 2 concentration levels of the original mix under test: 10 percent ilmenite (90 percent silica) and 20 percent ilmenite (80 percent silica). For each of these M samples, N = 3 separate SEM/EDX samples were drawn. In this test, ilmenite is the element of interest. By plotting the linear trend of the M sample s known concentration versus the average of the N samples, a much higher resolution of elemental analysis can be performed. The resulting trend also shows how the noise is affecting the data, and at what point (of smaller concentrations) is it impractical to try to extract any further useful data.

Lane, John↗
NASA NTRS2012

Analysis of Microcrafters in Materials Specimens after Long-Term Exposure on ISS Surface

The "Komplast" experiment has been carried out on the ISS by the Khrunichev Space Center jointly with other Russian scientific centers since 1998. The experiment incorporates the "Komplast" cartridges on the FGB exterior, which are fitted with materials specimens and sensors. The cartridges were sent into orbit together with FGB on 20 November 1998. In March 2011, two of the cartridges were taken back from the ISS by the "Discovery" American space shuttle after being exposed in the open space for 12 years. In the framework of this experiment the subject of analysis is the effect of the space environment on the exposed specimens of various materials. This report covers the analysis results of the surface morphology of various materials taken from the "Komplast" cartridges exposed to hits of micrometeors and micronic particles of space debris. Analysis is made of microcraters of 5 to 250 mcm in specimens of polished metals and silicone comprised in the sensor for micrometeoric particles. The report represents optic and scanning electron microscope images of craters formed in the specimens by high-velocity and low-velocity particles impacting the surface. By virtue of the electronic microscope, data on composition of the substance in the craters and of the substance of the low-velocity particles are obtained. The data make it possible to differentiate the particles as the natural-origin particles or anthropogenic-origin space debris particles. Distribution of craters and low-velocity particles in the size range of 5 to 50 mcm is obtained. The data are compared with the existing models of fluxes of natural-origin and artificial-origin microparticles on the ISS orbit. Inhomogeneous particles of complicated configuration are discovered on the surface of the analyzed specimens, whose origin are not uniquely determined and are to be the subject of further study.

Shaevich, S. K.↗
NASA NTRS2010

Fast, High-Resolution Terahertz Radar Imaging at 25 Meters

We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50x50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of a concealed threat at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the system requirements for eventually achieving sub-second or video-rate THz radar imaging.

standoff concealed weapons detection↗
NASA NTRS2019

The RELAMPAGO Lightning Mapping Array: Preliminary Scientific Results and Application to GLM Calibration and Validation

During November 2018 through April 2019, an 11-station NASA lightning mapping array (LMA) was installed in the Cordoba region of Argentina, in support of GOES-16 Geostationary Lightning Mapper (GLM) calibration and validation, as well as the Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) field campaign. This region of Argentina is well known for frequent, intense thunderstorms and severe weather. The LMA was monitored remotely via the Internet throughout its deployment, but due to bandwidth limitations no real-time data were available. Custom GOES-16 imagery provided by NASA SPoRT assisted with monitoring of thunderstorm cases. Occasional site visits were done to obtain data disks, perform routine maintenance, and troubleshoot problems. During the deployment the network captured lightning in a variety of storm modes, including ordinary and severe multicells, supercells, and mesoscale convective systems. Many examples of normal-polarity thunderstorms, as well as a few examples of anomalously charged thunderstorms, were observed. Long (100+ km) horizontally stratified lightning flashes, as well as lightning in overshooting tops, also were frequently observed. Supporting research radar observations were available through January 2019, with operational radar coverage available after that time. Some cases featured supporting ABI meso scanning. This presentation will report on the LMA deployment in context with the RELAMPAGO field campaign, show results from some representative case studies, and will provide initial comparisons to GLM observations.

Lang, Timothy J.↗
NASA NTRS2007

Electrostatic Evaluation of the SRB Velostat(Trademark) Pads

During RSRM Grain inspection, pads constructed of Velostat are grounded and installed in the RSRM bore enabling inspectors to move throughout the bore during the inspection. Velostat pads are installed by grounding the first pad installed and subsequent pads are installed overlapping the previously installed pad maintaining a conductive path to facility ground. Pads are removed upon completion of the inspection in a reverse fashion. As the pads are removed scanning of propellant surfaces is performed per OMRS. During PPICI Audit of B5308.006 (Forward Segment Grain Inspection) in October 07 one audit finding noted that electrostatic scanning of propellant surfaces was being performed during removal of conductive pads following grain inspection. ATK does not perform electrostatic scanning of propellant surfaces during pad removal following final inspection at the plant. The integrated team consisting of NASA SE, USA SE, USA QE, ATK LSS, ATK Systems Safety and ATK DE concurred that electrostatic scanning of propellant surfaces was unnecessary as the conductive pads are grounded. Additional time spent in bore performing scanning presents itself as additional risk. Technicians reported that they have never seen any voltage readings while scanning propellant surfaces during pad removal. USA Systems engineering has written KB 17530 in response to the finding which will delete the requirement (item 2 B47GEN.ll0) to scan propellant surfaces during pad removal. As a result of an E3 panel discussion on December 13, 2007, it was decided that verification of the electrical grounding of the Velostat pads be verified.

Buhler, Charles R.↗
DOE OSTI2024

Characterizations of two-photon absorption process induced by defects in aluminum nitride using Z-scan method

Abstract In this work, we reported two-photon absorption (TPA) measurements for aluminum vacancies in Aluminum nitride single crystals. We measured the linear transmission and identified the defect levels. Using the Z-scan method, we measured the TPA coefficients of the transitions between defect levels from 380 nm to 735 nm. The transition occurs between the aluminum vacancies defect levels. Furthermore, the power dependence shows good linear fitting, confirming the TPA mechanism. These results will be helpful for the design and fabrication of ultra-low loss waveguides and integrated photonics in the ultraviolet spectral range.

Engineering↗
NASA NTRS2005

Discovering Recurring Anomalies in Text Reports Regarding Complex Space Systems

Many existing complex space systems have a significant amount of historical maintenance and problem data bases that are stored in unstructured text forms. For some platforms, these reports may be encoded as scanned images rather than even searchable text. The problem that we address in this paper is the discovery of recurring anomalies and relationships between different problem reports that may indicate larger systemic problems. We will illustrate our techniques on data from discrepancy reports regarding software anomalies in the Space Shuttle. These free text reports are written by a number of different penp!e, thus the emphasis and wording varies considerably.

Zane-Ulman, Brett↗