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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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Task and work performance on Skylab missions 2, 3, and 4: Time and motion study: Experiment M151

Human task performance was evaluated under weightlessness conditions during long duration space flight in order to study the characteristics of the adaptation function. Results show that despite pronounced variability in training schedules and in initial reaction to the Skylab environment, in-flight task performance was relatively equivalent among Skylab crews, and behavioral performance continued to improve from beginning to end of all missions.

Kubis, J. F.↗
NASA NTRS1977

The solar-terrestrial observatory as a major module of a space station

The solar-terrestrial environment is a dynamic, tightly coupled system in which variable solar energy is transmitted through electromagnetic radiation and the solar wind to the earth's magnetosphere and atmosphere. The constantly changing solar input and the continuous redistribution of energy near the earth combine to determine the characteristics of our global environment. An understanding and subsequent management of this environment will require a coordinated set of observations of solar processes and the accompanying magnetospheric and atmospheric responses. A major element in this observational plan should be a Solar-Terrestrial Observatory module of a manned Space Station in which instruments and experimental techniques developed during short-duration Spacelab flights will be applied to extended missions in both low-altitude and geosynchronous orbits.

Chappell, C. R.↗
NASA NTRS1979

Recommendations of the panels: Panel on in-flight measurements

The attenuation factor for aircraft other than the B-747 in reducing the ambient ozone concentrations which enter the cabin is obtained. The need to continue NASA Global Air Sampling Program measurements was expressed for three main purposes; testing new filters, correlation of complaints with ozone levels, and ambient ozone data. The need to continue cooperation between NASA and industry is indicated. Concern with regard to the correlation of ozone levels and complaints was given. The need to measure the variability of ozone within the aircraft cabin was investigated. The requirement for an onboard ozone monitor on all aircraft is discussed.

Rogers, J.↗
NASA NTRS1980

Thunderstorm-environment interactions determined with three-dimensional trajectories

Diagnostically determined three dimensional trajectories were used to reveal some of the scale interaction processes that occur between convective storms and their environment. Data from NASA's fourth Atmospheric Variability Experiment are analyzed. Two intense squall lines and numerous reports of severe weather occurred during the period. Convective storm systems with good temporal and spatial continuity are shown to be related to the development and movement of short wave circulation systems aloft that propagate eastward within a zonal mid tropospheric wind pattern. These short wave systems are found to produce the potential instability and dynamic triggering needed for thunderstorm formation. The environmental flow patterns, relative to convective storm systems, are shown to produce large upward air parcel movements in excess of 50 mb/3h in the immediate vicinity of the storms. The air undergoing strong lifting originates as potentially unstable low level air traveling into the storm environment from southern and southwestern directions. The thermo and hydrodynamical processes that lead to changes in atmospheric structure before, during, and after convective storm formation are described using total time derivatives of pressure or net vertical displacement, potential temperature, and vector wind calculated by following air parcels.

Wilson, G. S.↗
NASA NTRS1985

Observations of Cygnus X-3 above 10(15) eV from 1979 - 1984

The ultra high energy gamma-ray source, cygnus X-3, has been observed more or less continuously with an array sensitive to 10 to the 15th power ev primaries between 1 Jan. 1979 and 31 Dec. 1984. There is evidence for time variability in the phase of gamma-ray emission over this period.

Lambert, A.↗
NASA NTRS1988

A continuum damage model of fatigue-induced damage in laminated composites

A model is presented which predicts the stress-strain behavior of continuous fiber reinforced laminated composites in the presence of microstructural damage. The model is based on the concept of continuum damage mechanics and uses internal state variables to characterize the various damage modes. The associated internal state variable growth laws are mathematical models of the loading history induced development of microstructural damage. The model is demonstrated by using it to predict the response of damaged AS-4/3502 graphite/epoxy laminate panels.

Harris, Charles E.↗
NASA NTRS1992

Inferring total canopy APAR from PAR bidirectional reflectances and vegetation indices in tallgrass prairie

The fraction of photosynthetically active radiation (PAR) absorbed by a vegetated canopy (APARc) or landscape (APARs) is a critical parameter in climate processes. A grassland study examined: 1) whether APARs can be estimated from PAR bidirectional exitance fractions; and 2) whether APARs is correlated with spectral vegetation indices (SVIs). Data were acquired with a high resolution continuous spectroradiometer at 4 sun angles on grassland sites. APARs was computed from the scattered surface PAR exitance fractions. The nadir APARs value was the most variable diurnally; it provided a good estimate of the average surface APARs at ~95 percent. APARc was best represented by exitance factors between 30-60* forward.

Middleton, Elizabeth M.↗
NASA NTRS2002

Electronic Dimmable Ballasts for High-Intensity Discharge Sodium Vapor and Metal Halide Lamps

Two types of high-intensity discharge lamps were tested using dimmable ballasts. The main purpose for evaluating this lighting system was to determine its efficacy for saving power. Whereas previous variable level lighting systems for HID lamps in Advanced Life Support applications were adjustable in two or three steps using capacitive switching, this system allows for continuously adjustable lamp output. This type of lighting system when used as part of an Advanced Life Support biomass production system would provide only the amount of light energy a crop needed at any particular point in its growth cycle. Since most of the equivalent system mass in an ALS system is from the light energy required to grow the crops, controlling that light energy dynamically over a continuous range of operation would dramatically reduce the power consumption and reduce system mass.

Boulanger, Richard↗
NASA NTRS2007

Ejecta- and Size-Scaling Considerations from Impacts of Glass Projectiles into Sand

One of the most promising means of learning how initial impact conditions are related to the processes leading to the formation of a planetary-scale crater is through scaling relationships.1,2,3 The first phase of deriving such relationships has led to great insight into the cratering process and has yielded predictive capabilities that are mathematically rigorous and internally consistent. Such derivations typically have treated targets as continuous media; in many, cases, however, planetary materials represent irregular and discontinuous targets, the effects of which on the scaling relationships are still poorly understood.4,5 We continue to examine the effects of varying impact conditions on the excavation and final dimensions of craters formed in sand. Along with the more commonly treated variables such as impact speed, projectile size and material, and impact angle,6 such experiments also permit the study of changing granularity and friction angle of the target materials. This contribution presents some of the data collected during and after the impact of glass spheres into a medium-grained sand.

Anderson J. L. B.↗
NASA NTRS2014

From Earth to Space: Application of Biological Treatment for the Removal of Ammonia from Water

Managing ammonia is often a challenge in both drinking water and wastewater treatment facilities. Ammonia is unregulated in drinking water, but its presence may result in numerous water quality issues in the distribution system such as loss of residual disinfectant, nitrification, and corrosion. Ammonia concentrations need to be managed in wastewater effluent to sustain the health of receiving water bodies. Biological treatment involves the microbiological oxidation of ammonia to nitrate through a two‐step process. While nitrification is common in the environment, and nitrifying bacteria can grow rapidly on filtration media, appropriate conditions, such as the presence of dissolved oxygen and required nutrients, need to be established. This presentation will highlight results from two ongoing research programs - one at NASA's Johnson Space Center, and the other at a drinking water facility in California. Both programs are designed to demonstrate nitrification through biological treatment. The objective of NASA's research is to be able to recycle wastewater to potable water for spaceflight mission. To this end, a biological water processor (BWP) has been integrated with a forward osmosis secondary treatment system (FOST). Bacteria mineralize organic carbon to carbon dioxide as well as ammonia‐nitrogen present in the wastewater to nitrogen gas, through a combination of nitrification and denitrification. The effluent from the BWP system is low in organic contaminants, but high in total dissolved solids. The FOST system, integrated downstream of the BWP, removes dissolved solids through a combination of concentration‐driven forward osmosis and pressure driven reverse osmosis. The integrated system testing planned for this year is expected to produce water that requires only a polishing step to meet potable water requirements for spaceflight. The pilot study in California is being conducted on Golden State Water Company's Yukon wellsthat have hydrogen sulfide odor, color, total organic carbon, bromide, iron and manganese in addition to ammonia. A treatment evaluation, conducted in 2011, recommended the testing of biological oxidation filtration for the removal of ammonia and production of biologically stable water. A 8‐month pilot testing program was conducted to develop and optimize key design and operational variables. Steadystate operational data was collected to demonstrate long‐term performance and inform California Department of Public Health permitting of the full‐scale process. As ammonia continues to present challenges to water and wastewater systems, innovative strategies such as biological treatment can be applied to successfully manage it. This presentation will discuss application of cutting‐age research being conducted by NASA that will bridge existing information gaps, and benefit municipal utilities.

Ghosh, Amlan↗
NASA NTRS2014

From Earth to Space: Application of Biological Treatment for the Removal of Ammonia from Water

Managing ammonia is often a challenge in both drinking water and wastewater treatment facilities. Ammonia is unregulated in drinking water, but its presence may result in numerous water quality issues in the distribution system such as loss of residual disinfectant, nitrification, and corrosion. Ammonia concentrations need to be managed in wastewater effluent to sustain the health of receiving water bodies. Biological treatment involves the microbiological oxidation of ammonia to nitrate through a two‐step process. While nitrification is common in the environment, and nitrifying bacteria can grow rapidly on filtration media, appropriate conditions, such as the presence of dissolved oxygen and required nutrients, need to be established. This presentation will highlight results from two ongoing research programs - one at NASA's Johnson Space Center, and the other at a drinking water facility in California. Both programs are designed to demonstrate nitrification through biological treatment. The objective of NASA's research is to be able to recycle wastewater to potable water for spaceflight missions. To this end, a biological water processor (BWP) has been integrated with a forward osmosis secondary treatment system (FOST). Bacteria mineralize organic carbon to carbon dioxide as well as ammonia‐nitrogen present in the wastewater to nitrogen gas, through a combination of nitrification and denitrification. The effluent from the BWP system is low in organic contaminants, but high in total dissolved solids. The FOST system, integrated downstream of the BWP, removes dissolved solids through a combination of concentration‐driven forward osmosis and pressure driven reverse osmosis. The integrated system testing planned for this year is expected to produce water that requires only a polishing step to meet potable water requirements for spaceflight. The pilot study in California is being conducted on Golden State Water Company's Yukon wells that have hydrogen sulfide odor, color, total organic carbon, bromide, iron and manganese in addition to ammonia. A treatment evaluation, conducted in 2011, recommended the testing of biological oxidation filtration for the removal of ammonia and production of biologically stable water. An 8‐month pilot testing program was conducted to develop and optimize key design and operational variables. Steadystate operational data was collected to demonstrate long‐term performance and inform California Department of Public Health permitting of the full‐scale process. As ammonia continues to present challenges to water and wastewater systems, innovative strategies such as biological treatment can be applied to successfully manage it. This presentation will discuss application of cutting‐age research being conducted by NASA that will bridge existing information gaps, and benefit municipal utilities.

Pickering, Karen↗
NASA NTRS2015

Variability and Predictability of West African Droughts. A Review in the Role of Sea Surface Temperature Anomalies

The Sahel experienced a severe drought during the 1970s and 1980s after wet periods in the 1950s and 1960s. Although rainfall partially recovered since the 1990s, the drought had devastating impacts on society. Most studies agree that this dry period resulted primarily from remote effects of sea surface temperature (SST) anomalies amplified by local land surface-atmosphere interactions. This paper reviews advances made during the last decade to better understand the impact of global SST variability on West African rainfall at interannual to decadal time scales. At interannual time scales, a warming of the equatorial Atlantic and Pacific/Indian Oceans results in rainfall reduction over the Sahel, and positive SST anomalies over the Mediterranean Sea tend to be associated with increased rainfall. At decadal time scales, warming over the tropics leads to drought over the Sahel, whereas warming over the North Atlantic promotes increased rainfall. Prediction systems have evolved from seasonal to decadal forecasting. The agreement among future projections has improved from CMIP3 to CMIP5, with a general tendency for slightly wetter conditions over the central part of the Sahel, drier conditions over the western part, and a delay in the monsoon onset. The role of the Indian Ocean, the stationarity of teleconnections, the determination of the leader ocean basin in driving decadal variability, the anthropogenic role, the reduction of the model rainfall spread, and the improvement of some model components are among the most important remaining questions that continue to be the focus of current international projects.

West Africa↗
NASA NTRS2004

A LEO Hyperspectral Mission Implementation for Global Carbon Cycle Observations

For both terrestrial and ocean carbon cycle science objectives, high resolution (less than l0 nm) imaging spectrometers capable of acquiring multiple regional to global scale observations per day should enable the development of new remote sensing measurements for important but as yet unobservable variables, with the overall goal of linking both terrestrial and ocean carbon cycle processes to climate variability. For terrestrial research, accurate estimates of carbon, water and energy (CWE) exchange between the terrestrial biosphere and atmosphere a needed to id- the geographical locations and temporal dynamics of carbon sources/sinks and to improve regional climate models and climate change assessments. It is an enormous challenge to estimate CWE exchange from the infrequent temporal coverage and sparse spectral information provided by most single polar-orbiting, earth-looking satellite. The available satellite observations lack a sufficient number of well-placed narrow bands from which to derive spectral indices that capture vegetation responses to stress conditions associated with down-regulation of photosynthesis. Physiological status can best be assessed with spectral indices based on continuous, narrow bands in the visible/near infrared spectra, as can seasonal and annual terrestrial productivity. For coastal and ocean constituents, narrow-band observations in the ultraviolet and visible are essential to investigate the variability, dynamics and biogeochemical cycles of the world's coastal and open ocean regions, which will in turn help in measuring ocean productivity and predicting the variability of ocean carbon uptake and its role in climate change.

Gervin, Janette C.↗
NASA NTRS1978

Spectrophotometric variability in the Be star Gamma Cassiopeiae - Simultaneous ultraviolet and H-alpha observations

Simultaneous scans of the ultraviolet Si IV and Mg II resonance doublets in the spectrum of Gamma Cas with the Copernicus satellite during 64 continuous hours of observation, and H-alpha scans from a ground station, are described. No evidence is found for a rotation period of Gamma Cas, but narrow emission components in both ultraviolet doublets are reported along with a sudden emission increase on January 29.1, 1977 UT which appeared to be present in both H-alpha and the ultraviolet lines.

Slettebak, A.↗
NASA NTRS2010

The Effect of Satellite Observing System Changes on MERRA Water and Energy Fluxes

Because reanalysis data sets offer state variables and fluxes at regular space / time intervals, atmospheric reanalyses have become a mainstay of the climate community for diagnostic purposes and for driving offline ocean and land models. Although one weakness of these data sets is the susceptibility of the flux products to uncertainties because of shortcomings in parameterized model physics, another issue, perhaps less appreciated, is the fact that continual but discreet changes in the evolving observational system, particularly from satellite sensors, may also introduce artifacts in the time series of quantities. In this paper we examine the ability of the NASA MERRA (Modern Era Retrospective Analysis for Research and Applications) and other recent reanalyses to determine variability in the climate system over the satellite record (approximately the last 30 years). In particular we highlight the effect on the reanalysis of discontinuities at the junctures of the onset of passive microwave imaging (Special Sensor Microwave Imager) in late 1987 as well as improved sounding and imaging with the Advanced Microwave Sounding Unit, AMSU-A, in 1998. We first examine MERRA fluxes from the perspective of how physical modes of variability (e.g. ENSO events, Pacific Decadal Variability) are contaminated by artificial step-like trends induced by the onset of new moisture data these two satellite observing systems. Secondly, we show how Redundancy Analysis, a statistical regression methodology, is effective in relating these artifact signals in the moisture and temperature analysis increments to their presence in the physical flux terms (e.g. precipitation, radiation). This procedure is shown to be effective greatly reducing the artificial trends in the flux quantities.

Robertson, Franklin R.↗
NASA NTRS2011

The Effect of Satellite Observing System Changes on MERRA Water and Energy Fluxes

Because reanalysis data sets offer state variables and fluxes at regular space / time intervals, atmospheric reanalyses have become a mainstay of the climate community for diagnostic purposes and for driving offline ocean and land models. Although one weakness of these data sets is the susceptibility of the flux products to uncertainties because of shortcomings in parameterized model physics, another issue, perhaps less appreciated, is the fact that continual but discreet changes in the evolving observational system, particularly from satellite sensors, may also introduce artifacts in the time series of quantities. In this paper we examine the ability of the NASA MERRA (Modern Era Retrospective Analysis for Research and Applications) and other recent reanalyses to determine variability in the climate system over the satellite record (approx. the last 30 years). In particular we highlight the effect on the reanalysis of discontinuities at the junctures of the onset of passive microwave imaging (Special Sensor Microwave Imager) in late 1987 and, more prominently, with improved sounding and imaging with the Advanced Microwave Sounding Unit, AMSU-A, in 1998. We first examine MERRA fluxes from the perspective of how physical modes of variability (e.g. ENSO events, Pacific Decadal Variability) are contained by artificial step-like trends induced by the onset of new moisture data these two satellite observing systems. Secondly, we show how Redundancy Analysis, a statistical regression methodology, is effective in relating these artifact signals in the moisture and temperature analysis increments to their presence in the physical flux terms (e.g. precipitation, radiation). This procedure is shown to be effective greatly reducing the artificial trends in the flux quantities.

Robertson, Franklin R.↗
NASA NTRS2017

Changing Seasonality of Panarctic Tundra Vegetation in Relationship to Climatic Variables

Potential climate drivers of Arctic tundra vegetation productivity are investigated to understand recent greening and browning trends documented by maximum normalized difference vegetation index (NDVI) (MaxNDVI) and time-integrated NDVI (TI-NDVI) for 19822015. Over this period, summer sea ice has continued to decline while oceanic heat content has increased. The increases in summer warmth index (SWI) and NDVI have not been uniform over the satellite record. SWI increased from 1982 to the mid-1990s and remained relatively flat from 1998 onwards until a recent upturn. While MaxNDVI displays positive trends from 19822015, TI-NDVI increased from 1982 until 2001 and has declined since. The data for the first and second halves of the record were analyzed and compared spatially for changing trends with a focus on the growing season. Negative trends for MaxNDVI and TI-NDVI were more common during 19992015 compared to 19821998.

sea ice↗
DOE OSTI2024

Prediction of Distributed River Sediment Respiration Rates Using Community-Generated Data and Machine Learning

River sediment microbial respiration is a key indicator of ecosystem functioning and the biogeochemical fluxes across this critical zone link surface and subsurface waters. As such, there is tremendous interest in measuring and mapping these respiration rates. Respiration observations are expensive and labor intensive; there is limited data available to the community. An open science, collaborative initiative is collecting samples for respiration rate analysis and multi-scale metadata; this evolving data set is being used for making machine learning (ML) predictions at unsampled sites to help inform continued community engagement. However, it is a challenge to find an optimum configuration for ML models to work with this feature-rich (i.e., 100+ possible input variables) data set. Here, we present results from a two-tiered approach to managing the analysis of this complex data set: (a) a stacked ensemble of models that automatically optimizes hyperparameters and manages the training of many models and (b) feature permutation importance to detect the most important features in the models. The major elements of this workflow are modular, portable, open, and cloud-based thus making this implementation a potential template for other applications. The models developed here predict that sediment organic matter chemistry is one of the most important features for predicting sediment respiration rate. Other larger-scale, important features fall into the categories of climatic, ecological, geological, and fluvial settings. Leveraging these larger-scale features to generate data-driven estimates of river sediment respiration rates reveals spatially consistent but heterogeneous patterns across the river network of the Columbia River Basin.

54 ENVIRONMENTAL SCIENCES↗