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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

High Spatial Resolution Mid-IR Imaging of V838 Monocerotis: Evidence of New Circumstellar Dust Creation

The eruptive variable V838 Monocerotis experienced three dramatic outbursts in early 2002. Its unexpectedly erratic photometric behavior wes matched by strong spectroscopic variability, in which the srar transitioned through the F, K, G spectral type s in 2002 February, reseabled a M5 supergiant by 2002 Aprll, and had a L-type super qiant spectram in 2002 October. The star is also infamous for producisg e spectacu lar light echo whose evolction has beer traced by HST/ACS. We report high sFatial resolution 11.2 and 18.1 micron imagicq of V838 Nonoceroris obrained with Genini Ob servatory's Klchelle in 2007 March. The 2007 flux density of the unresclved stellar core of is rouqhly 2 tixes brighter than zhaz observed in 2C04. We interpret tkese aata as evidecce t-at V838 Mon has experienced a new circums~ellar dust creatioc evezt. We suggest that this newly c reated dust is Likely clumpy, and speculate that one (or ore) of Ekese clumps migh t have passed through the line-cf-sight in late 2036, prodccing the brief rnalti-wav elength pkotonetric event reported by Bond (2006) and Yunari ez a1 (2007). A gap o f spatially exzended therrrzl (18 micron) emission is present over radial distances of 1860 - 93000 AU from che central source. Assuming ejecta material expands at a constant velocity of 300-500 km/s, this gap suggests that no prior significanz circ unstellar dust production events have occurred withiin the past approx. 900-1500 years.

Winsiewski, John P.↗
DOE OSTI2016

Inverse modeling of pan-Arctic methane emissions at high spatial resolution: what can we learn from assimilating satellite retrievals and using different process-based wetland and lake biogeochemical models?

Understanding methane emissions from the Arctic, a fast-warming carbon reservoir, is important for projecting future changes in the global methane cycle. Here we optimized methane emissions from north of 60° N (pan-Arctic) regions using a nested-grid high-resolution inverse model that assimilates both high-precision surface measurements and column-average SCanning Imaging Absorption spectroMeter for Atmospheric CHartogrphY (SCIAMACHY) satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes were integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated with six biogeochemical models. In our estimates, in 2005, global methane emissions were in the range of 496.4–511.5 Tg yr –1 , and pan-Arctic methane emissions were in the range of 11.9–28.5 Tg yr –1 . Methane emissions from pan-Arctic wetlands and lakes were 5.5–14.2 and 2.4–14.2 Tg yr –1 , respectively. Methane emissions from Siberian wetlands and lakes are the largest and also have the largest uncertainty. Our results indicate that the uncertainty introduced by different wetland models could be much larger than the uncertainty of each inversion. We also show that assimilating satellite retrievals can reduce the uncertainty of the nested-grid inversions. The significance of lake emissions cannot be identified across the pan-Arctic by high-resolution inversions, but it is possible to identify high lake emissions from some specific regions. In contrast to global inversions, high-resolution nested-grid inversions perform better in estimating near-surface methane concentrations.

58 GEOSCIENCES↗
NASA NTRS1986

High spatial resolution passive microwave sounding systems

Two extensive series of flights aboard the ER-2 aircraft were conducted with the MIT 118 GHz imaging spectrometer together with a 53.6 GHz nadir channel and a TV camera record of the mission. Other microwave sensors, including a 183 GHz imaging spectrometer were flown simultaneously by other research groups. Work also continued on evaluating the impact of high-resolution passive microwave soundings upon numerical weather prediction models.

Staelin, D. H.↗
NASA NTRS1996

High Spatial Resolution Investigations of Microchannel Plate Imaging Properties for UV Detectors

Microchannel plate (MCP) photon counting detectors are currently being used with great success on many of the recent NASA/ESA ultraviolet (UV) astrophysics missions that make observations in the 1OO A - 1600 A range. These include HUT, the Wide Field Camera on ROSAT, EUVE, ALEXIS, ORFEUS, and SOHO. These devices have also been chosen to fly on future UV astrophysics missions such as FUSE, FUVITA, IMAGE, and both the HST STIS and Advanced Camera instruments. During the period of this award we have fabricated a dual-chamber vacuum test facility to carry out laboratory testing of detector resolution, image stability and linearity, and flat field performance to enable us to characterize the performance of MCPs and their associated read-out architectures. We have also fabricated and tested a laboratory 'test-bed' delay line detector, which can accommodate MCP's with a wide range of formats and run at high data rates, to continue our studies of MCP image fixed pattern noise, and particularly for new small pore MCP's which have recently come onto the market. These tests were mainly focussed on the assessment of cross delay-line (XDL) and double delay line (DDL) anode read-out schemes, with particular attention being focussed on flat-field and spatial resolution performance.

Siegmund, Oswald↗
DOE OSTI2015

Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a −1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2–42.7 Tg a −1 , as compared to 24.9–27.0 Tg a −1 in the EDGAR and EPA bottom-up inventories, and 30.0–44.5 Tg a −1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern–central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29–44 % of US anthropogenic methane emissions to livestock, 22–31 % to oil/gas, 20 % to landfills/wastewater, and 11–15 % to coal. Wetlands contribute an additional 9.0–10.1 Tg a −1 .

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Mass spectrometric imaging as a high-spatial resolution tool for functional genomics: Tissue-specific gene expression of TT7 inferred from heterogeneous distribution of metabolites in Arabidopsis flowers

Laser desorption/ionization (LDI) mass spectrometry imaging (MSI) was used to acquire chemical images of flavonoid metabolites on the surface of wild-type and mutant (tt7) Arabidopsis thaliana flowers. Flavonoids were localized to the petals and carpels of flowers, with tissue heterogeneity in the petals. Specifically, kaempferol and/or its glycosides were abundant in the distal region of petals and quercetin and its downstream flavonoids were highly enriched in the more proximal region of petals. As a result of a mutation in the TT7 gene which blocks the conversion of dihydrokaempferol to dihydroquercetin, the downstream metabolites, quercetin, isohamnetin, and their glycosides, were not observed in the mutant flowers. Instead, the metabolites in an alternative pathway, kaempferol and/or its glycosides, were as highly abundant on the proximal region of the petals as in the distal region. In addition, the combined flavonoid amounts on the proximal region of petals in the wild-type are almost equivalent to the amounts of kaempferol and/or its glycosides in the mutant. This strongly suggests that the expression of the TT7 gene is localized on the proximal part of the petal while the other genes in the upper stream pathway are evenly expressed throughout the petal. Most importantly, this work demonstrates MSI of metabolites can be utilized for the localization of gene expression.

47 OTHER INSTRUMENTATION↗
NASA NTRS1975

Auger electron spectroscopy at high spatial resolution and nA primary beam currents

An experimental Auger microprobe system is described which incorporates a field-emission electron gun and total beam currents in the nanoampere range. The distinguishing characteristics of this system include a large multistation UHV specimen chamber, pulse counting and fully digital Auger signal-processing techniques, and digital referencing methods to eliminate the effects of beam instabilities. Some preliminary results obtained with this system are described, and it is concluded that field-emission electron sources can be used for high-resolution Auger electron spectroscopy with primary-beam spots of less than 100 nm and beam currents of the order of 1 nA.

Todd, G.↗
NASA NTRS1994

High-spatial-resolution passive microwave sounding systems

The principal contributions of this combined theoretical and experimental effort were to advance and demonstrate new and more accurate techniques for sounding atmospheric temperature, humidity, and precipitation profiles at millimeter wavelengths, and to improve the scientific basis for such soundings. Some of these techniques are being incorporated in both research and operational systems. Specific results include: (1) development of the MIT Microwave Temperature Sounder (MTS), a 118-GHz eight-channel imaging spectrometer plus a switched-frequency spectrometer near 53 GHz, for use on the NASA ER-2 high-altitude aircraft, (2) conduct of ER-2 MTS missions in multiple seasons and locations in combination with other instruments, mapping with unprecedented approximately 2-km lateral resolution atmospheric temperature and precipitation profiles, atmospheric transmittances (at both zenith and nadir), frontal systems, and hurricanes, (3) ground based 118-GHz 3-D spectral images of wavelike structure within clouds passing overhead, (4) development and analysis of approaches to ground- and space-based 5-mm wavelength sounding of the upper stratosphere and mesosphere, which supported the planning of improvements to operational weather satellites, (5) development of improved multidimensional and adaptive retrieval methods for atmospheric temperature and humidity profiles, (6) development of combined nonlinear and statistical retrieval techniques for 183-GHz humidity profile retrievals, (7) development of nonlinear statistical retrieval techniques for precipitation cell-top altitudes, and (8) numerical analyses of the impact of remote sensing data on the accuracy of numerical weather predictions; a 68-km gridded model was used to study the spectral properties of error growth.

Staelin, D. H.↗
DOE OSTI2018

Variable location channels to improve efficiency and precision for direct ∇ T e measurements and high spatial resolution T e -profile measurements using electron cyclotron emission

Electron cyclotron emission (ECE) diagnostics that use variable location channels based on yttrium iron garnet (YIG) bandpass filters improve the precision and the efficiency of measurements of electron temperature (T e ) profiles and fluctuations (δT e ). These variable frequency filters were substituted for fixed frequency filters in the intermediate frequency section to achieve the required higher resolution over a target radial range, just before the experiment. In this paper, we present the proof-of-principle for high temporal resolution measurement of the electron temperature gradient, via real-time slewing of a YIG filter for relocation of an ECE channel during a long pulse. The key component is the application of YIG tunable filters with their narrow bandwidth and capability for a high slew rate of their center frequency. This application permits fast relocation of the ECE channels for direct measurement of the gradient and close spacing of channels to investigate the magnetic island’s dynamic behavior.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Predicting vehicular emissions in high spatial resolution using pervasively measured transportation data and microscopic emissions model

Air pollution related to traffic emissions pose an especially significant problem in cities; this is due to its adverse impact on human health and well-being. Previous studies which have aimed to quantify emissions from the transportation sector have been limited by either simulated or coarsely resolved traffic volume data. Emissions inventories form the basis of urban pollution models, therefore in this study, Global Positioning System (GPS) trajectory data from a taxi fleet of over 15,000 vehicles were analyzed with the aim of predicting air pollution emissions for Singapore. This novel approach enabled the quantification of instantaneous drive cycle parameters in high spatio-temporal resolution, which provided the basis for a microscopic emissions model. Carbon dioxide (CO2), nitrogen oxides (NOx), volatile organic compounds (VOCs) and particulate matter (PM) emissions were thus estimated. Highly localized areas of elevated emissions levels were identified, with a spatio-temporal precision not possible with previously used methods for estimating emissions. Relatively higher emissions areas were mainly concentrated in a few districts that were the Singapore Downtown Core area, to the north of the central urban region and to the east of it. Daily emissions quantified for the total motor vehicle population of Singapore were found to be comparable to another emissions dataset Results demonstrated that high resolution spatio-temporal vehicle traces detected using GPS in large taxi fleets could be used to infer highly localized areas of elevated acceleration and air pollution emissions in cities, and may become a complement to traditional emission estimates, especially in emerging cities and countries where reliable fine-grained urban air quality data is not easily available. This is the first study of its kind to investigate measured microscopic vehicle movement in tandem with microscopic emissions modeling for a substantial study domain.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

WORKSHOP ON URBAN SCALE PROCESSES AND THEIR REPRESENTATION IN HIGH SPATIAL RESOLUTION EARTH SYSTEM MODELS

It is essential that numerical models used to study physics, chemistry, and biology affecting the Earth system at regional and global scales represent the effects of urban areas on climate and the effects of changing the climate on urban areas. At the same time, it is essential to develop state of the art, simple and accurate urban models to better understand the relevant processes and also toaddress issues related to urban security against the spectra of chemical, biological and radiological (CBR) hazards. Towards bringing these communities together, a 2.5-day international workshop was held at Argonne National Laboratory (ANL) in the Chicago area on May 22-24, 2019. This workshop brought together national and international experts to develop a roadmap for a better understanding of the issues associated with urban areas and at enhancing the capabilities of regional and global Earth System models (ESMs) in representing the atmospheric dynamics and chemistry, unique aspects of the biosphere and land use, and human dimensions of the urban environment. This workshop was especially important to those developing very high-resolution versions of regional and global models. The workshop also discussed existing datasets, including in situ and satellite observations, and the emerging smart city sensing technologies and their possible use in model development (e.g., the NSF-funded Array of Things network currently operating in Chicago and expanding to other cities).

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2020

Evaluation and Validation of a High Spatial Resolution Satellite Soil Moisture Product over the Continental United States

The soil moisture (SM) data retrieved from the Soil Moisture Active and Passive (SMAP) satellite are available at a 9 km grid spacing since April 2015. This product can provide valuable information for research and applications in hydrology and other related fields. However, the resolution may be too coarse for applications at catchment or field scale. In this study, an established downscaling methodology, which had a major modification regarding its application on the SMAP 33 km domain, was implemented to develop a 1 km soil moisture product based on the SMAP 9 km data. The algorithm proposed here is based on the thermal inertia principle and developed by modeling the relationship between surface temperature difference and SM for different Normalized Difference Vegetation Index (NDVI) classes. The model functions were established and tuned using data from the NASA’s Land Information System (LIS) North America Land Data Assimilation System (NLDAS) and remotely sensed VISible/InfRared (VIS/IR) reflectance data from Long Term Data Record (LTDR) AVHRR (Advanced Very High Resolution Radiometer) for the growing season months of April-September 1981–2018. These were then implemented using the MODIS (Moderate Resolution Imaging Spectroradiometer) data over the Continental United States (CONUS) domain. Validation activities were carried out using in situ measurements distributed through the International Soil Moisture Network (ISMN). The validation results computed using the 1 km SM data showed that the R2, unbiased RMSE (root mean square error) and bias were improved relative to the 9 km SMAP product by 0.045, 0.018m3/m3 and 0.001m3/m3, respectively. The 1 km SM also exhibited a strong time-series autocorrelation. Further accuracy assessment analyses indicated that precipitation might contribute to the uncertainties in both the 9 km SMAP and 1 km downscaled SMAP SM products.

SMAP↗
NASA NTRS2007

High Spatial Resolution Thermal Infrared Remote Sensing Data for Analysis of the Atlanta, Georgia, Urban Heat Island Effect and Its Impacts on the Environment

The twenty-first century is the first "urban century" according to the United Nations Development Program. The focus of cities reflects awareness of the growing percentage of the world's population that lives in urban areas. In environmental terms, cities are the original producers of many of the global problems related to waste disposal, air and water pollution, and associated environmental and ecological challenges. Expansion of cities, both in population and areal extent, is a relentless process. In 2000, approximately 3 billion people representing about 40% of the global population, resided in urban areas. Urban population will continue to rise substantially over the next several decades according to UN estimates, and most of this growth will Occur in developing countries. The UN estimates that by 2025, 60% of the world's population will live in urban areas. As a consequence, the number of"megacities" (those cities with populations of 10 million inhabitants or more) will increase by 100 by 2025. Thus, there is a critical need to understand urban areas and what their impacts are on environmental, ecological and hydrologic resources, as well as on the local, regional, and even global climate. One of the more egregious side effects of urbanization is the increase in surface and air temperatures that lead to deterioration in air quality. In the United States, under the more stringent air quality guidelines established by the U.S. Environmental Protection Agency in 1997, nearly 300 counties in 34 states will not meet these new air quality standards for ground level ozone. Mitigation of the urban heat island (UHI) effect is actively being evaluated as a possible way to reduce ground ozone levels in cities and assist states in improving air quality. Foremost in the analysis of how the UHI affects air quality and other environmental factors is the use of remote sensing technology and data to characterize urban land covers in sufficient detail to quantifiably measure the impact of increased urban heating on air quality. The urban landscape impacts surface thermal energy exchanges that determine development of the UHI. This paper will illustrate how we are using high spatial remote sensing data collected over the Atlanta, Georgia metropolitan area in conjunction with other geographic information, to perform a detailed urban land cover classification and to determine the contribution of these land covers to the urban heat island effect. Also, the spatial arrangement of the land covers and the impact on urban heating from these selected patterns of development are evaluated. Additionally, this paper will show how these data are being used as inputs to improve air quality modeling for Atlanta, including potential benefits from UHI mitigation.

Quattrochi, Dale A.↗
DOE OSTI2020

High spatial resolution thermal conductivity mapping of SiC/SiC composites

Herein, silicon carbide (SiC) ceramic matrix composites are being investigated as a new generation of fuel cladding materials due to its higher accident tolerance compared to Zircaloy. Characterization of the thermal conductivity of SiC constituents and their interfaces and interphases in SiC/SiC composites is needed as inputs to models of cladding performance. We used time-domain thermoreflectance (TDTR) to map the thermal conductivity with a spatial resolution of 2 µm. The SiC/SiC composite is comprised of Hi-Nicalon Type S fibers in a matrix made by chemical vapor infiltration (CVI matrix). The interphase material is a pyrolytic carbon/SiC multilayer. We report thermal conductivity maps of the SiC fiber and SiC matrix at temperatures of 25 °C, 90 °C, 164 °C, and 250 °C. The fiber has a uniform and isotropic thermal conductivity of 22 W m -1 K -1 at 25 °C; the thermal conductivity of fiber is approximately independent of temperature. The matrix thermal conductivity is not uniform and varies from 50 to 120 W m -1 K -1 at 25 °C; the thermal conductivity of the matrix scales approximately with the inverse of the square root of temperature, i.e., ∝ 1/T 1/2 . The thermal conductivity of the interphase at room temperature is 6 W m -1 K -1 . The calculated spatially averaged thermal conductivity of this SiC/SiC composite at 1000°C is 29 W m -1 K -1 .

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Achieving high spatial resolution using a microchannel plate detector with an economic and scalable approach

We report a second generation position-sensitive microchannel plate detector using the induced signal approach has been realized. This detector is presently capable of measuring the incident position of electrons, photons, or ions. To assess the spatial resolution, the masked detector was illuminated by electrons. The initial, measured spatial resolution of 276 μm FWHM was improved by requiring a minimum signal amplitude on the anode and by employing digital signal processing techniques. The resulting measured spatial resolution of 119 μm FWHM corresponds to an intrinsic resolution of 98 μm FWHM when the effect of the finite slit width is de-convoluted. This measurement is a substantial improvement from the last reported spatial resolution of 466 μm FWHM using the induced signal approach. To understand the factors that limit the measured resolution, the performance of the detector is simulated.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗