SEARCH · Engineering Papers

Results for “High spatial resolution”

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.

SourceResearch connectionFrom yearThrough year

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

At least 73 records · Page 4

All sources NASA NTRS DOE OSTI

NASA NTRS1992

High spatial resolution continuum and H-alpha imaging of the high-redshift IRAS source FSC 10214+4724

New observations are reported which support the view that the high-redshift IRAS source FSC 10214+4724 is a rare extreme example of the class of ultraluminous infrared galaxies observed in the local universe. The presence of two continuum components and a compact H-alpha source suggests that a merger between two or more gas-rich systems has triggered the production of a powerful dust-enshrouded quasar which is responsible for the bulk of the luminosity.

Soifer, B. T.↗

NASA NTRS2021

High-Spatial-Resolution Mass Rates From GRACE and GRACE-FO: Global and Ice Sheet Analyses

GRACE and GRACE-FO gravimetry data are unique in its ability to observe global water mass variability and has frequently been applied for the determination of global mass rates to quantify the impacts of climate change and human activity on global freshwater availability and land ice evolution. However, its relatively coarse spatial resolution of ∼300-500 km at monthly intervals precludes its direct use to measure mass changes in smaller drainage basins and individual glacier systems. We present a new global high resolution mascon product that improves spatial resolution and signal recovery by estimating trends directly from more than 16 years of Level 1B GRACE and GRACE-FO data. We compare this product to independent gravimetry spherical harmonic trend estimates and to ice sheet mass rates derived from ICESat and ICESat-2 laser altimetry. We demonstrate enhanced global signal recovery and improved agreement with ICESat/ ICESat-2 and discuss likely causes for the remaining discrepancies between the gravimetry and laser altimetry solutions.

Bryant D. Loomis↗

DOE OSTI2021

Distributed Fiber Sensors With High Spatial Resolution in Extreme Radiation Environments in Nuclear Reactor Cores

This paper is a comprehensive experimental report on the neutron radiation effects of distributed optical fiber sensors with enhanced Rayleigh scattering profiles in an in-pile environment. Femtosecond laser direct writing was used to inscribe Type-II modifications in standard telecom fibers and radiation-hardened fibers with fluorine-doped cores. Rayleigh backscattering signals were enhanced for continuous 1.5 m. In-pile lead-out sensors tests were carried out at the MIT Research Reactor for two months, which was operated at a nominal power of 5.7 MW with fast neutron (>0.1 MeV) flux of 1.29 × 1014 n/cm2/s and an in-core temperature of up to 560°C. Using the Optical Frequency Domain Reflectometry technique, the backscattering profiles of fiber sensors were interrogated with a 3-cm spatial resolution to monitor the temperature profile of the reactor. Results show that laser inscribed Type-II modifications in the form of nanogratings are highly stable against extreme temperature and ionizing radiation. Both standard telecom fibers and radiation-hardened fibers with laser-enhanced Rayleigh profiles can continuously perform distributed temperature measurements over the entire duration of the in-pile testing. Temperature coefficients of sensors and spectral shift quality were studied as functions of total radiation fluence. To the best of our knowledge, we present for the first time, the temperature profile of an operating nuclear reactor core with 3-cm spatial resolution, enabled by distributed fiber sensors with laser-enhanced Rayleigh scattering profiles. The high spatial resolution measurements can provide valuable data for the design and validation of digital twin and virtual reality of nuclear energy systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2022

Spectroscopy-based isotopic (δ 13 C) analysis for high spatial resolution of carbon exchange in the rhizosphere

The rhizosphere is a highly dynamic zone bridging plant roots with needed nutrient resources in soil. While the rhizosphere may be small, it has a disproportionally large impact on plant success and biomass production. A suite of rhizosphere-hosted microbial and geochemical interactions facilitate nutrient acquisition by plant roots, and, in turn, the roots stimulate these processes by supplying organic carbon into the rhizosphere. The small physical dimensions of the rhizosphere, however, can constrain efforts to elucidate key carbon exchange processes and their spatial extent and localization. We present a method for spatially resolved δ 13 C analysis of rhizosphere samples by coupling laser ablation (LA) sampling with isotopic analysis using capillary absorption spectroscopy (CAS) which differs from conventional mass spectrometer (MS) approaches. The CAS system has high sensitivity (requires fewer nanomoles of CO 2 per analysis) than comparable MS systems, which enables reduced sample size requirements to thereby improve spatial resolution (from 25 μm to as low as a projected 5 μm spatial resolution). We demonstrate the utility of CAS using rhizosphere samples from switchgrass plants exposed to 13 CO 2 . As a result, this technique will provide a capability for tracking the extent and spatial distribution of root exudate into the rhizosphere at highly detailed spatial scales.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRSDate not supplied

Application of High-Spatial Resolution LA-MC-ICP-MS in Planetary Materials

High-precision stable and radiogenic isotopic measurements of planetary materials can help elucidate processes taking place during early Solar System formation, as well as during subsequent planetary differentiation. Laser Ablation Multi Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) adds the valuable ability of preserving the spatial context of these isotopic measurements, by sampling small sample volumes (~10 – 60 um diameter) using a pulsed laser system. In the Center for Isotope Cosmochemistry and Geochronology (CICG) at NASA Johnson Space Center, these in-situ isotopic measurements are primarily made using the Applied SpectraTM iX-fs-Tandem LA-LIBS Instrument coupled to the Nu InstrumentsTM SP1700 MC-ICP-MS. The instrumental set-up also provides simultaneous Laser Induced Breakdown Spectroscopy (LIBS) measurements and the potential use of a low energy path with a collision/reaction cell for additional interference removal, though we focus here on the typical high-energy LA-MC-ICP-MS operation. We will provide examples of stable (e.g., Mg) and radiogenic (e.g., Lu-Hf) isotopic systems measured in planetary materials and their terrestrial analogs. The measurement of mass dependent Mg isotopic variations is an important tool for reconstructing processes such as evaporation and condensation of solids in the solar nebula. For early Solar System samples, Mg isotope measurements are also important for the short-lived (t1/2 = 0.7 Ma) Al-Mg chronometer. During laser ablation analyses, the measurement of the Al-Mg isotopic system is made in medium mass resolution (RP ~9500 at ~20% transmission) to limit interferences from 48Ti2+ and 48Ca2+ on 24Mg+, in addition to 52Cr2+ and 12C14N+ on 26Mg+. Measured in the mineral zircon, the 176Lu-176Hf decay system is often used for understanding the growth of continents on Earth, and is also a vital aid in deciphering early large-scale planetary differentiation processes, such as the crystallization of the lunar magma ocean, which is thought to be responsible for much of the Moon’s crust. Lu-Hf measurements are made in low resolution mode (RP <2000), with 10 ion masses (from 171Yb to 180Hf) measured simultaneously to facilitate corrections for isobaric interferences from 176Yb and 176Lu on 176Hf.

Jacob B Setera↗

NASA NTRS2017

Using High Spatial Resolution Satellite Imagery to Map Forest Burn Severity Across Spatial Scales in a Pine Barrens Ecosystem

As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30 m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (less than or equal to 5 m) from very-high-resolution (VHR) data. We assessed a 432 ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severity was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal - pre- and post-fire event - WorldView-2 (WV-2) imagery at 2 m spatial resolution. We first evaluated our approach using 1 m by 1 m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10 m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15 m by 15 m fixed-area plots (inter-crown scale) with the post-fire 0.10 m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). This work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the less than 30 m scale and VHR approaches could significantly advance our ability to characterize fire effects on forest ecosystems.

Meng, Ran↗

NASA NTRS1988

High spatial resolution 10 micron imaging of IRC + 10216

Precise high-resolution 10-micron images of the carbon star IRC + 10216 have been obtained with a scanned linear array. The low noise and high dynamic range of these images permit deconvolution of the telescope point-spread function, revealing the radial brightness distribution of the circumstellar dust shell: approximate reflection symmetry is found in west-east scans, with a distinct division into two components of diameter about 0.40 and 2.2 arcsec. It is shown that this morphology is consistent with published interferometric data that had cast doubt upon an earlier, idealized two-component model. The observed brightness distribution implies that the circumstellar dust density may deviate substantially from the 1/r squared radial dependence expected for spherically symmetric outflow with constant velocity and constant rate of mass loss.

Bloemhof, E. E.↗

NASA NTRS1978

The analysis of high spatial resolution UV and X-ray images by computational modeling

Very high resolution stereoscopic images of high temperature loop structures observed at UV and X-ray wavelengths in the solar corona can be used to understand physical processes in the corona. An existing computational model is described and sample results are given to demonstrate that computational modeling of coronal structures can indeed take advantage of very high resolution images. The sample results include the run of temperature and number density along a typical loop and the variation of the differential emission measure with temperature. The integration of the differential emission measure with temperature along a column commensurate with an instrument's spatial resolution is the relevant parameter obtained from UV and X-ray observations. The effects of loop geometry and energy input are examined.

Vesecky, J. F.↗

NASA NTRS1990

High spatial resolution mapping of the Cepheus A region at 20, 50, and 100 microns

The Cepheus A region at 20 microns has been mapped, and a bright, unresolved central source with a peak flux of 41 Jy into a 4.0 arcsec x 4.3 arcsec beam has been detected. One-dimensional slit scans have been obtained in two perpendicular directions across Cepheus A at 50 and 100 microns using a high spatial-resolution sampling technique. The temperature and optical depth profile of the far-IR emission are determined, and a peak temperature of 46 K and peak 100 micron optical depth of 0.4 are derived. Maximum entropy deconvolution of the far-IR scans indicate that there is a bright central core with clumpy extended emission. Within errors the position of the 50/100 micron peak is the same as the 20-micron source; this is interpreted as indicating that the 20 micron radiation represents the short-wavelength emission from the core of the dust cloud seen in the far-IR. It is concluded that an embedded source provides the major source of luminosity in the Cepheus A region.

Ellis, H. B., Jr.↗

DOE OSTI2023

Examining Infrasound Propagation at High Spatial Resolution Using a Nodal Seismic Array

Infrasound—acoustic waves in the atmosphere below 20 Hz—is a useful monitoring tool. Topography and atmospheric structure strongly control infrasound propagation, and at common source–receiver distances neither of these effects can be ignored when quantitative source constraints are sought. Detailed spatial measurements of the infrasound wavefield would inform propagation models and improve source estimates. However, the “large-N” deployment strategy now well-known in seismology has not yet been realized for infrasound studies. Here, we use the 900-node seismic array from the 2014 Imaging Magma Under St. Helens (iMUSH) experiment as a proxy for a large-N infrasound network, by leveraging acoustic–seismic coupled arrivals. The active-source component of iMUSH consisted of 23 shallowly buried explosions around Mount Saint Helens volcano; these explosions produced epicentral infrasound recorded on the nodes. We find that the bulk presence of ground-coupled infrasound on the nodes is controlled by wind noise and source–receiver distance, with observed arrivals for eight explosions. Explosions with the most extensive coupling produce complex spatial waveform patterns across the array. These patterns are related to both topographic and atmospheric propagation effects, as well as spatially variable site (coupling) effects. We compare our observations to simple topographic diffraction and high-resolution wind advection models, and full-wave numerical simulations. We find strong spatial correlations between (a) coupled arrival strength and modeled topographic obstruction and (b) coupled arrival time and along-path winds. Our seismoacoustic analyses and results are applicable to other existing and future nodal seismic data sets and can expand the utility of such deployments.

58 GEOSCIENCES↗

DOE OSTI2025

High Spatial Resolution Mapping of Retained Fission Gas

Fission gas isotopic analysis provides quantitative high precision determination of irradiated nuclear fuel burnup, offers diagnostic value, and informs fuel performance models. A measurement capability has been developed at Idaho National Laboratory (INL) for the release of retained fission gas using a focused laser and static noble gas mass spectrometry (MS) analysis. This high resolution (10s microns spot size) capability was demonstrated using Xe implanted metal foils.

07 - ISOTOPES AND RADIATION SOURCES↗

NASA NTRS1986

A high spatial resolution study of microwave flare precursors

Several examples of preflare changes are provided from VLA high-resolution microwave data, which show that in general the active region increases in intensity and polarization over a period of several tens of minutes prior to the onset of a flare in that region. However, this phenomenon by itself does not appear to be sufficient to trigger a flare. It is shown that at 10 min or less before flare onset something else happens, usually in the form of one of the following three features: (1) sudden change of polarization of the flaring region, (2) change of orientation of the neutral plane separating one polarity from another in a bipolar region, and (3) appearance of new sources in the immediate vicinity of some preexisting structure of the active region. All three features are consistent with the emergence of new flux, which interacts with a preexisting region to form a neutral or current sheet. The formation of the latter is ultimately responsible for triggering the onset of a flare.

Kundu, M. R.↗

DOE OSTI2021

Robust Optical Sensor Technology for Real-Time Monitoring of Solid Oxide Fuel Cells with High Spatial Resolutions

This SOFC core technology development program will develop an integrated fiber optical sensor technology to perform real-time and high-resolution measurements in both planar and tubular fuel cells and fuel cell assembly to monitor operations and structural changes of SOFCs. The new fiber sensing solution can monitor hundreds of points in the 3D fuel cell structures with 5-mm spatial resolutions using one single optical fiber.

30 DIRECT ENERGY CONVERSION↗

NASA NTRS1983

A sampling procedure to guide the collection of narrow-band, high-resolution spatially and spectrally representative reflectance data

A multistage sampling procedure using image processing, geographical information systems, and analytical photogrammetry is presented which can be used to guide the collection of representative, high-resolution spectra and discrete reflectance targets for future satellite sensors. The procedure is general and can be adapted to characterize areas as small as minor watersheds and as large as multistate regions. Beginning with a user-determined study area, successive reductions in size and spectral variation are performed using image analysis techniques on data from the Multispectral Scanner, orbital and simulated Thematic Mapper, low altitude photography synchronized with the simulator, and associated digital data. An integrated image-based geographical information system supports processing requirements.

Brand, R. R.↗

DOE OSTI2025

High spatial resolution charge sensing of quantum Hall states

Charge distribution offers a unique fingerprint of important properties of electronic systems, including dielectric response, charge ordering, and charge fractionalization. Here, we develop an architecture for charge sensing in two-dimensional electronic systems in a strong magnetic field. We probe local change of the chemical potential in a proximitized detector layer using scanning tunneling microscopy, allowing us to infer the chemical potential and the charge profile in the sample. Our technique has both high energy (<0.3 meV) and spatial (<10 nm) resolution exceeding that of previous studies by an order of magnitude. We apply our technique to study the chemical potential of quantum Hall liquids in monolayer graphene under high magnetic fields and their responses to charge impurities. The chemical potential measurement provides a local probe of the thermodynamic gap of quantum Hall ferromagnets and fractional quantum Hall states. The screening charge profile reveals spatially oscillatory response of the quantum Hall liquids to charge impurities and is consistent with the composite Fermi liquid picture close to the half-filling. Our technique also paves the way to map moiré potentials, probe Wigner crystals, and investigate fractional charges in quantum Hall and Chern insulators.

charge sensing↗

NASA NTRS1988

Cloud field classification based upon high spatial resolution textural features. I - Gray level co-occurrence matrix approach

Stratocumulus, cumulus, and cirrus clouds were identified on the basis of cloud textural features which were derived from a single high-resolution Landsat MSS NIR channel using a stepwise linear discriminant analysis. It is shown that, using this method, it is possible to distinguish high cirrus clouds from low clouds with high accuracy on the basis of spatial brightness patterns. The largest probability of misclassification is associated with confusion between the stratocumulus breakup regions and the fair-weather cumulus.

Welch, R. M.↗

NASA NTRS2012

High Spatial Resolution Studies of Epithermal Neutron Emission from the Lunar Poles: Constraints on Hydrogen Mobility

The data from the collimated sensors of the LEND instrument are shown to be of exceptionally high quality. Counting uncertainties are about 0.3% relative and are shown to be the only significant source of random error, thus conclusions based on small differences in count rates are valid. By comparison with the topography of Shoemaker crater, the spatial resolution of the instrument is shown to be consistent with the design value of 5 km for the radius of the circle over which half the counts from the lunar surface would be determined. The observed epithermal-neutron suppression factor due to the hydrogen deposit in Shoemaker crater of 0.25 plus or minus 0.04 cps is consistent with the collimated field-of-view rate of 1.7 cps estimated by Mitrofanov et al. (2010a). The statistical significance of the neutron suppressed regions (NSRs) relative to the larger surrounding polar region is demonstrated, and it is shown that they are not closely related to the permanently shadowed regions. There is a significant increase in H content in the polar regions independent of the H content of the NSRs. The non-NSR H content increases directly with latitude, and the rate of increase is virtually identical at both poles. There is little or no increase with latitude outside the polar region. Various mechanisms to explain this steep increase in the non-NSR polar H with latitude are investigated, and it is suggested that thermal volatilization is responsible for the increase because it is minimized at the low surface temperatures close to the poles.

neutron↗

NASA NTRS1972

A liquid radiation detector with high spatial resolution

Detector, using point anode, minimizes problem of oblique tracks by permitting construction of very thin counter. Detector is useful in cosmic ray and high energy physics research and X-ray and neutron diffraction technology.

Alvarez, L.↗