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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Environmental observations of the Great Salt Lake Basin from ERTS-1

Some ERTS-1 observations of snowcover, turbidity variations in the major lakes, surface water area changes, land use features, and phenomena associated with industrial emissions are described. Turbidity patterns in the major water bodies can be observed that appear to be related to the general wind flow, or to lake circulation patterns, and the chemical or biological constituents in the water. Monthly, seasonal, and annual changes in surface water extent can be monitored and serve as indicators of water availability. Time and space variations in snowcover that are a function of exposure or time of year were observed in some regions. Specific measurements of snowline altitude during the major snowmelt period of 1973 were obtained. The existence and effect of industrial emission on vegetation were found to be detectable.

Smith, A. F.↗
NASA NTRS1992

DMS emissions from Sphagnum-dominated wetlands

The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S was investigated by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in trophic status. Experiments were conducted in wetlands in New Hampshire (NH), and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods, and GC with flame photometric detection. Emissions of DMS dominated fluxes. In NH, DMS fluxes were greater than 1.6 micromol/m(sup -2)d(sup -1) in early summer, 1989 when temperatures were warm and the water table was approximately 5 cm below the surface. These rates are several-fold faster than average oceanic rates of DMS emission. A rapid drop in the water table resulted in a 6-fold decrease in DMS emissions in late July. In 1990, a new beaver dam kept water levels above the surface and S emissions were much lower than during 1989. The elimination of the beaver and a drop in the water table in August produced a rapid increase in S gas emissions. Emissions of DMS were highest in the most oligotrophic areas. Mire 239 (ELA) was irrigated with sulfuric and nitric acids to simulate acid rain. S emissions were determined before and after an acidification event in control and experimental areas in both minerotrophic and oligotrophic regions. Emissions of DMS were higher in the acidified areas compared to unacidified controls. Emissions were also much higher in the oligotrophic regions compared to the minerotrophic ones. Despite the wide differences in S gas fluxes (20-fold), it was difficult to determine whether acidification or variations in trophic status was not responsible for differences in S gas emissions. DMS emitted into the atmosphere was not derived from the water table but originated in peat in the unsaturated zone.

Hines, Mark E.↗
NASA NTRS2004

Electrochemical Processes Enhanced by Acoustic Liquid Manipulation

Acoustic liquid manipulation is a family of techniques that employ the nonlinear acoustic effects of acoustic radiation pressure and acoustic streaming to manipulate the behavior of liquids. Researchers at the NASA Glenn Research Center are exploring new methods of manipulating liquids for a variety of space applications, and we have found that acoustic techniques may also be used in the normal Earth gravity environment to enhance the performance of existing fluid processes. Working in concert with the NASA Commercial Technology Office, the Great Lakes Industrial Technology Center, and Alchemitron Corporation (Elgin, IL), researchers at Glenn have applied nonlinear acoustic principles to industrial applications. Collaborating with Alchemitron Corporation, we have adapted the devices to create acoustic streaming in a conventional electroplating process.

Oeftering, Richard C.↗
NASA NTRS1991

Properties of novel CVD graphite fibers and their bromine intercalation compounds

A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF.

Gaier, James R.↗
NASA NTRS1992

Properties of hybrid CVD/PAN graphite fibers and their bromine intercalation compounds

A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF.

Gaier, James R.↗
NASA NTRS1992

Emissions of biogenic sulfur gases from northern bogs and fens

Sulfur gases are important components of the global cycle of S. They contribute to the acidity of precipitation and they influence global radiation balance and climate. The role of terrestrial sources of biogenic S and their effect on atmospheric chemistry remain as major unanswered questions in our understanding of the natural S cycle. The role of northern wetlands as sources and sinks of gaseous S by measuring rates of S gas exchange as a function of season, hydrologic conditions, and gradients in tropic status was investigated. Experiments were conducted in wetlands in New Hampshire, particularly a poor fen, and in Mire 239, a poor fen at the Experimental Lakes Area (ELA) in Ontario. Emissions were determined using Teflon enclosures, gas cryotrapping methods and gas chromatography (GC) with flame photometric detection. Dynamic (sweep flow) and static enclosures were employed which yielded similar results. Dissolved S gases and methane were determined by gas stripping followed by GC.

Demello, William Zamboni↗
NASA NTRS2022

Keweenaw Bay Water Resources: Turbidity Data Decision Support for Shoreline Assessment and Management in Lake Superior'S Keweenaw Bay

The Keweenaw Bay Indian Community (KBIC) has shoreline along the south of Lake Superior that is contaminated with copper stamp sands from legacy mining. The stamp sands have been capped with sandy-loam soils and restored native species, but erosion and flooding threaten to re-deposit these stamp sands onto wetlands and into the bay. Erosion and flooding also threaten loss of beaches and shoreline, infrastructure, wetland restoration projects, and coastal highways, which has driven shoreline armoring. However, while shoreline armoring can be effective in protecting the intended areas, it can also exacerbate erosion in nearby unarmored areas, so its net impact on the shoreline is yet to be quantified. The DEVELOP team partnered with KBIC and the Environmental Protection Agency (EPA) to utilize imagery from Landsat 8 Operational Land Imager (OLI) and Sentinel-2 Multispectral Instrument (MSI) in order to analyze turbidity proxies. The results from these analyses showed that seasonal variation in study area was greatest during the season dominated by rain, but spatial variability across our study period did not show a clear trend. These results will be used to better inform future shoreline management efforts and support resilience in the face of more coastal erosion.

remote sensing↗
NASA NTRS1980

Thermal Pollution Mathematical Model. Volume 4: Verification of Three-Dimensional Rigid-Lid Model at Lake Keowee

The rigid lid model was developed to predict three dimensional temperature and velocity distributions in lakes. This model was verified at various sites (Lake Belews, Biscayne Bay, etc.) and th verification at Lake Keowee was the last of these series of verification runs. The verification at Lake Keowee included the following: (1) selecting the domain of interest, grid systems, and comparing the preliminary results with archival data; (2) obtaining actual ground truth and infrared scanner data both for summer and winter; and (3) using the model to predict the measured data for the above periods and comparing the predicted results with the actual data. The model results compared well with measured data. Thus, the model can be used as an effective predictive tool for future sites.

Lee, S. S.↗
NASA NTRS2021

Satellite Remote Sensing to Assess Cyanobacterial Bloom Frequency Across the United States at Multiple Spatial Scales

Cyanobacterial blooms can have negative effects on human health and local ecosystems. Field monitoring of cyanobacterial blooms can be costly, but satellite remote sensing has shown utility for more efficient spatial and temporal monitoring across the United States. Here, satellite imagery was used to assess the annual frequency of surface cyanobacterial blooms, defined for each satellite pixel as the percentage of images for that pixel throughout the year exhibiting detectable cyanobacteria. Cyanobacterial frequency was assessed across 2,196 large lakes in 46 states across the continental United States (CONUS) using imagery from the European Space Agency’s Ocean and Land Colour Imager for the years 2017 through 2019. In 2019, across all satellite pixels considered, annual bloom frequency had a median value of 4% and a maximum value of 100%, the latter indicating that for those satellite pixels, a cyanobacterial bloom was detected by the satellite sensor for every satellite image considered. In addition to annual pixel-scale cyanobacterial frequency, results were summarized at the lake- and state-scales by averaging annual pixel-scale results across each lake and state. For 2019, average annual lake-scale frequencies also had a maximum value of 100%, and Oregon and Ohio had the highest average annual state-scale frequencies at 65% and 52%. Pixel-scale frequency results can assist in identifying portions of a lake that are more prone to cyanobacterial blooms, while lake- and state-scale frequency results can assist in the prioritization of sampling resources and mitigation efforts. Satellite imagery is limited by the presence of snow and ice, as imagery collected in these conditions are quality flagged and discarded. Thus, annual bloom frequencies within nine climate regions were investigated to determine whether missing data biased results in climate regions more prone to snow and ice, given that their annual summaries would be weighted toward the summer months when cyanobacterial blooms tend to occur. Results were unbiased by the time period selected in most climate regions, but a large bias was observed for the Northwest Rockies and Plains climate region. Moderate biases were observed for the Ohio Valley and the Southeast climate regions. Finally, a clustering analysis was used to identify areas of high and low cyanobacterial frequency across CONUS based on average annual lake-scale cyanobacterial frequencies for 2019. Several clusters were identified that transcended state, watershed, and eco-regional boundaries. Combined with additional data, results from the clustering analysis may offer insight regarding large-scale drivers of cyanobacterial blooms.

remote sensing↗
NASA NTRS1975

Remote profiling of lake ice using an S-band short pulse radar aboard an all-terrain vehicle

An airborne short-pulse radar system to measure ice thickness was designed. The system supported an effort to develop an all-weather Great Lakes Ice Information System to aid in extending the winter navigation season. Experimental studies into the accuracy and limitations of the system are described. A low power version was operated from an all-terrain vehicle on the Straits of Mackinac during March 1975. The vehicle allowed rapid surveying of large areas and eliminated the ambiguity in location between the radar system and the ground truth ice auger team. It was also possible to the effects of snow cover, surface melt water, pressure ridging, and ice type upon the accuracy of the system. Over 25 sites were explored which had ice thicknesses from 29 to 60 cm. The maximum radar overestimate was 9.8 percent, while the maximum underestimate was 6.6 percent. The average error of the 25 measurements was 0.1 percent.

Cooper, D. W.↗
NASA NTRS1983

Eclipse-related measurements of middle-atmosphere electrical parameters

Measurements of electrical conductivity and its constituent parameters, charge density and ion mobility, are presented for the solar eclipse rocket campaign conducted at Red Lake, Ontario, Canada. Three parachute-borne probes (two Gerdien condensers and a blunt probe) were flown during the eclipse which occurred on 26 February 1979. Additional payloads launched at other times provided important supplemental background measurements. The entire launch series occurred during aurorally active conditions, as indicated by the probe measurements. Specifically, positive conductivity enhancements above 45 km demonstrate the dominance of auroral ionization as a source for positive ions in the region. Such effects evidenced during the eclipse make it difficult to determine the extent to which the decrease in positive conductivity above 60 km is eclipse-related. The negative conductivity component associated with free electrons displays solar dependence both during the eclipse and for the other measurement periods. In spite of the aurorally active conditions, rapid electron loss was observed during totality, thus indicating the importance of non-ionizing solar effects on electrons in the region.

Mitchell, J. D.↗
NASA NTRSDate not supplied

Anthropogenic-Induced Drought: Escalating Mental Health Crises and Environmental Inequities

This study investigates the relationship between the Great Salt Lake (GSL) decline and air quality, focusing on PM2.5 concentrations and their impacts on public health. As the GSL continues to shrink, it has become a significant source of dust emissions, posing serious health and environmental risks to the surrounding areas. There search examines how diminishing water levels in the GSL, driven by climate change, agricultural water use, and urban development, affect local populations' mental health. Adopting an interdisciplinary approach, the study considers the long-term effects of air quality on mental health in relation to inorganic particulate matter, gaseous pollutants, and social vulnerability.

Maheshwari Neelam↗
NASA NTRS1994

Natural frequency of uniform and optimized tetrahedral truss platforms

Qualitative and quantitative estimates for the fundamental frequency of uniform and optimized tetrahedral truss platforms are determined. A semiempirical equation is developed for the frequency of free-free uniform trusses as a function of member material properties, truss dimensions, and parasitic (nonstructural) mass fraction Mp/Mt. Optimized trusses with frequencies approximately two times those of uniform trusses are determined by varying the cross-sectional areas of member groups. Trusses with 3 to 8 rings, no parasitic mass, and member areas up to 25 times the minimum area are optimized. Frequencies computed for ranges of both Mp/Mt and the ratio of maximum area to minimum area are normalized to the frequency of a uniform truss with no parasitic mass. The normalized frequency increases with the number of rings, and both frequency and the ratio of maximum area to minimum area decrease with increasing Mp/Mt. Frequency improvements that are achievable with a limited number of member areas are estimated for a 3-ring truss by using Taguchi methods. Joint stiffness knockdown effects are also considered. Comparison of optimized and baseline uniform truss frequencies indicates that tailoring can significantly increase structural frequency; maximum gains occur for trusses with low values of Mp/Mt. This study examines frequency trends for ranges of structural parameters and may be used as a preliminary design guide.

Wu, K. Chauncey↗
NASA NTRS1975

Enhancement and evaluation of Skylab photography for potential land use inventories, part 1

The author has identified the following significant results. Three sites were evaluated for land use inventory: Finger Lakes - Tompkins County, Lower Hudson Valley - Newburgh, and Suffolk County - Long Island. Special photo enhancement processes were developed to standardize the density range and contrast among S190A negatives. Enhanced black and white enlargements were converted to color by contact printing onto diazo film. A color prediction model related the density values on each spectral band for each category of land use to the spectral properties of the various diazo dyes. The S190A multispectral system proved to be almost as effective as the S190B high resolution camera for inventorying land use. Aggregate error for Level 1 averaged about 12% while Level 2 aggregate error averaged about 25%. The S190A system proved to be much superior to LANDSAT in inventorying land use, primarily because of increased resolution.

Hardy, E. E.↗
NASA NTRS2009

Real-Time Assessment of Robot Performance During Remote Exploration Operations

To ensure that robots are used effectively for exploration missions, it is important to assess their performance during operations. We are investigating the definition and computation of performance metrics for assessing remote robotic operations in real-time. Our approach is to monitor data streams from robots, compute performance metrics, and provide Web-based displays of these metrics for assessing robot performance during operations. We evaluated our approach for measuring robot performance with the K10 rovers from NASA Ames Research Center during a field test at Moses Lake Sand Dunes (WA) in June 2008. In this paper we present the results of evaluating our software for robot performance and discuss our conclusions from this evaluation for future robot operations.

SBIR TOPIC X7.02 PHASE 1↗
NASA NTRS1995

Extraction of ozone and chlorophyll-A distribution from AVIRIS data

The potential of airborne imaging spectrometry for assessing and monitoring natural resources is studied. Therefore, an AVIRIS scene of the NASA's MacEurope 1991 campaign - acquired in Central Switzerland - is used. The test site consists of an urban area, the Lake Zug with its surrounding fields, the Rigi mountain in the center of the test site, and the Lake of Four Cantons. The region is covered by the AVIRIS flight #910705, run 6 and 7 of the NASA ER-2 aircraft resulting in an average nominal pixel size of about 18 m. Simultaneous to the ER-2 overflight spectroradiometric measurements have been taken in various locations. Preselected reference targets were measured in the field with a GER Mark V spectroradiometer, and radiance measurements were taken to the lake using a Li-Cor LI 1800UW specroradiometer below and above the water surface. A comprehensive meteorological data set was obtained by joining the POLLUMET experiment which carried out measurements to investigate the summer smog in Switzerland on the same day. The quality assessment for the actual data set can be found in detail in Meyer et al. A parametric approach calculating the location of the airplane was used to simulate the observation geometry. This parametric preprocessing procedure, which takes care of effects of flight line and attitude variations as well as the pixel-by-pixel topographic corrections is described in Meyer.

Schaepman, M.↗
NASA NTRS1990

Radial spreading of viscous-gravity currents with solidifying crust

In the present investigation of solidifying-crust effects on the dynamics and surface morphology of radial viscous-gravity currents, polyethylene glycol inflows into the base of a tank holding a cold sucrose solution are used as analogs. As the radial current advanced away from the inlet, its surface solidified and deformed through a combination of folding anf fracturing. When cooling was sufficiently rapid, solid crust formed and caused the spreading rate to increase; progressively colder experiments revealed a sequence of surface morphologies resembling features of cooling lava flows and lava lakes, including multiarmed rift structures with shear offsets and bulbous lobate forms resembling pillow lavas on the ocean floor.

Fink, Jonathan H.↗
NASA NTRS1973

Coastal and submarine features on MSS imagery of Southeastern Massachusetts: Comparison with conventional maps

Three ERTS-1, MSS images of southeastern Massachusetts, including Cape Cod Bay, Cape Cod, and Nantucket Sound, show a variety of dynamic geologic and hydrologic phenomena. Coastal features imaged include the coastline at different time in the tidal cycle, harbors, lakes and ponds, marshes (wetlands), and beach and dune areas; submarine features include tidal flats, shoals, dredged and natural channels, and bars. Comparison with conventional maps at 1:1,000,000 and 1:250,000 scales show many inaccuracies between the ERTS imagery and the two map scales. The ERTS-1 imagery can be used to increase the accuracy of these maps, portray additional environmental information, and provide the capability for frequent updating of maps at such scales. ERTS-1 imagery provides a very cost effective method for provision of certain types of environmental data for Cape Cod and environs.

Williams, R. S., Jr.↗