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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Mechanistic studies on reduced exercise performance and cardiac deconditioning with simulated zero gravity

The primary purpose of this research is to study the physiological mechanisms associated with the exercise performance of rats subjected to conditions of simulated weightlessness. A secondary purpose is to study related physiological changes associated with other systems. To facilitate these goals, a rodent suspension model was developed (Overton-Tipton) and a VO2 max testing procedure was perfected. Three methodological developments occurred during this past year deserving of mention. The first was the refinement of the tail suspension model so that (1) the heat dissipation functions of the caudal artery can be better utilized, and (2) the blood flow distribution to the tail would have less external constriction. The second was the development on a one-leg weight bearing model for use in simulated weightlessness studies concerned with change in muscle mass, muscle enzyme activity, and hind limb blood flow. The chemical body composition of 30 rats was determined and used to develop a prediction equation for percent fat using underwater weighing procedures to measure carcass specific gravity and to calculate body density, body fat, and fat free mass.

Tipton, Charles M.↗
NASA NTRS2009

Homocysteine and Cognitive Performance in Elders with Self-Neglect

Elevated plasma homocysteine has been associated with altered cognitive performance in older adults. Elders referred to Adult Protective Services (APS) for self-neglect have been reported to have elevated plasma homocysteine levels and to suffer from cognitive impairment. This study assesses the association, if any, between plasma homocysteine and cognitive performance among elders with self-neglect. Methods: Sixty-five community-living adults, 65 years of age and older, reported to Adult Protective Services for self-neglect and 55 matched controls (matched for age, ethnicity, gender and socio-economic status) consented and participated in this study. The research team conducted in-home comprehensive geriatric assessments which included the mini-mental state exam (MMSE), the 15-item geriatric depression scale (GDS), the Wolf-Klein Clock Drawing Tests (CDT) and a comprehensive nutritional biochemistry panel, which included plasma homocysteine. Student s t tests and Pearson correlations were conducted to assess for bivariate associations. Results: Elders with self-neglect had significantly higher plasma homocysteine levels (M=12.68umol/L, sd=4.4) compared to the controls (M=10.40umol/L, sd=3.61;t=3.21, df=127, p=.002). There were no statistically significant associations between cognitive performance and plasma homocysteine in the self-neglect group, however there was a significant correlation between plasma homocysteine and the CDT among the controls (r=-.296, p=.022). Conclusion: Mean plasma homocysteine levels were significantly higher in elders with self-neglect, however, they do not appear to be related to cognitive performance, indicating that cognitive impairment in elder self-neglect involve mechanisms other than hyperhomocysteinemia. These findings warrant further investigation

Burnett, J.↗
NASA NTRS1986

Observation of reconnection phenomena at synchronous orbit

SCATHA satellite observations of large-amplitude magnetic field oscillations in the magnetosheath and in the associated plasma are studied. Large-amplitude variations in the magnetosheath magnetic field intensity with a quasi-period of 10 s were observed. Nearly static structures of high-beta plasma associated with the magnetic field minima and low-beta plasma associated with the magnetic field maxima were observed convecting toward the earth. The morphology of charged particle data for the transition between the magnetosphere and the magnetosheath for a northward magnetosheath magnetic field is presented. A convection electric field of about 9 mV/m was inferred from the spectral difference between solar and antisolar drifting ions in the magnetosheath near a magnetopause rotational discontinuity. A trapped component was observed in the magnetosheath plasma during both northward and southward magnetosheath magnetic fields. It is concluded that flux transfer events arise from the interaction of the earthward convecting plasma filaments with the magnetospheric magnetic field at the magnetopause.

Croley, D. R., Jr.↗
NASA NTRS2021

NASA's Surface Biology and Geology Concept Study: Status and Next Steps

The National Academies Decadal Survey for Earth Science recommended that NASA pursue global imaging spectroscopy and thermal infrared measurements in the coming decade [1]. Both measurements would offer repeat coverage on approximately five-day to biweekly cadence, with comprehensive coverage of the globe's coastal and terrestrial area. This would be an unprecedented volume of data with the potential to transform remote sensing practice. To address this recommendation, NASA has sponsored a concept study by NASA research centers and associated university partners (https://sbg.jpl.nasa.gov). This study is determining a family of architecture options - including launch vehicle, spacecraft, instrument, and suborbital components - that could address the Decadal Survey objectives. The architecture study is driven by science needs and builds on input of the research community. As of this writing, the study is entering a phase in which a large field of system possibilities is pared down to a representative handful for an ultimate decision by NASA.

Imaging Spectroscopy↗
NASA NTRS2004

A Convective Vorticity Vector Associated With Tropical Convection: A 2D Cloud-Resolving Modeling Study

Although dry/moist potential vorticity is a useful physical quantity for meteorological analysis, it cannot be applied to the analysis of 2D simulations. A convective vorticity vector (CVV) is introduced in this study to analyze 2D cloud-resolving simulation data associated with 2D tropical convection. The cloud model is forced by the vertical velocity, zonal wind, horizontal advection, and sea surface temperature obtained from the TOGA COARE, and is integrated for a selected 10-day period. The CVV has zonal and vertical components in the 2D x-z frame. Analysis of zonally-averaged and mass-integrated quantities shows that the correlation coefficient between the vertical component of the CVV and the sum of the cloud hydrometeor mixing ratios is 0.81, whereas the correlation coefficient between the zonal component and the sum of the mixing ratios is only 0.18. This indicates that the vertical component of the CVV is closely associated with tropical convection. The tendency equation for the vertical component of the CVV is derived and the zonally-averaged and mass-integrated tendency budgets are analyzed. The tendency of the vertical component of the CVV is determined by the interaction between the vorticity and the zonal gradient of cloud heating. The results demonstrate that the vertical component of the CVV is a cloud-linked parameter and can be used to study tropical convection.

Gao, Shou-Ting↗
NASA NTRS1972

The nature of the Herbig Ae- and Be-type stars associated with nebulosity.

A quantitative spectrophotometric study of the Herbig Ae and Be stars associated with nebulosity demonstrates that the majority have surface gravities appropriate to pre-main-sequence stars while the remainder have surface gravities characteristic of the zero-age main seee. This evidence, along with their gross spectroscopic and pc similarity to T Tauri-like stars and the fact that all these stars appear to be surrounded by circumstellar dust, places them among the youngest known stellar objects. The geometry of the circumstellar shells is discussed and the evidence seems to favor a nonspherical, possibly disklike shape. Finally, photographs taken with a 1-micron image-tube system reveal a large number of red stellar objects surrounding many of these stars. This suggests that the Herbig Ae and Be objects may be the brightest representatives of very recently formed stellar groups.-

Strom, S. E.↗
NASA NTRS1991

Analysis of open loop higher harmonic control at high airspeeds on a modern four-bladed articulated rotor

The effects of open loop higher harmonic control (HHC) on rotor hub loads, performance, and push rod loads of a Sikorsky S-76 helicopter rotor at high airspeeds (up to 200 knots) and moderate lift (10,000 lbs) were studied analytically. The analysis was performed as part of a wind tunnel pre-test prediction and preparation procedure, as well as to provide analytical results for post-test correlation efforts. The test associated with this study is to be concluded in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex (NFAC) at the NASA Ames Research Center. The results from this analytical study show that benefits from HHC can be achieved at high airspeeds. These results clear the way for conducting (with the requirement of safe pushrod loads) an open loop HHC test a high airspeeds in the 40- by 80-Foot Wind Tunnel using an S-76 rotor as the test article.

Kottapalli, Sesi↗
NASA NTRS1987

Vortex-fin interaction on a fighter aircraft

Water tunnel tests have been conducted to study the flow associated with fin buffet for twin-fin fighter aircraft using 1/48th scale F/A-18 models. Flow visualization made use of colored dyes to determine vortex patterns, and surface hot-film anemometry was used to study the turbulent energy and the frequencies present in the flow. Configurations tested include the full aircraft, aircraft without fins, aircraft without leading-edge-extensions, and aircraft without wings. Test Reynolds number ranged from 4300 to 12,800, with corresponding Mach numbers less than 10 to the -6th. The flow studies show that the LEX vortices burst just forward of the fins at about 25-deg angle-of-attack. Hot film anemometer signals show that fin surface turbulence increases with angle of attack, and that dominant frequencies appear in the flow when bursting occurs. The dominant frequencies correspond to a Strouhal number of about 0.7 for all speeds tested, and for all angles of attack for which vortex bursting was present.

Wentz, William H., Jr.↗
NASA NTRS1999

Investigation of Tropical Transport with UARS Data

Measurements of trace constituents obtained by instruments aboard the Upper Atmosphere Research Satellite (UARS) have been used to study transport processes associated with the quasi-biennial oscillation, laterally propagating Rossby waves, and upward propagating Kelvin waves in the tropical and subtropical upper troposphere and stratosphere. Mean vertical motions, vertical diffusivities and in-mixing rates were inferred from observations of the 'tape recorder' signal in near-equatorial stratospheric water vapor. The effect of the quasi-biennial oscillation (QBO) on tracer distributions in the upper half of the stratosphere was seen in a spectacular 'staircase' pattern, predominantly in the winter hemisphere, revealing the latitudinally asymmetric nature of QBO transport due to induced mean meridional circulations and modulation of lateral mixing associated with planetary Rossby waves. The propagation of Rossby waves across the equator in the westerly phase of the QBO was seen in tracer fields and corroborating United Kingdom Meteorological Office (UKMO) analyses; a modeling study of the effect of these waves on typical QBO wind profiles was performed. Water vapor in the upper troposphere and lower stratosphere was found to exhibit signatures of the tropical intraseasonal oscillation (TIO) and faster Kelvin waves in the two regions, respectively.

Dunkerton, Timothy J.↗
NASA NTRS1992

Analysis of open loop higher harmonic control at high airspeeds on a modern four-bladed articulated rotor

The effects of open loop higher harmonic control (HHC) on rotor hub loads, performance, and push rod loads of a Sikorsky S-76 helicopter rotor at high airspeeds (up to 200 knots) and moderate lift (10,000 lbs) were studied analytically. The present analysis was performed as a part of a wind tunnel pre-test prediction and preparation procedure, as well as to provide analytical results for post-test correlation efforts. The test associated with this study is to be concluded in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex (NFAC) at the NASA Ames Research Center. The results from this analytical study show that benefits from HHC can be achieved at high airspeeds. These results clear the way for conducting (with the requirement of safe pushrod loads) an open loop HHC test at high airspeeds in the 40- by 80-Foot Wind Tunnel using an S-76 rotor as the test article.

Kottapalli, Sesi↗
NASA NTRS1987

Association of a new type of gliding, filamentous, purple phototrophic bacterium inside bundles of Microcoleus chthonoplastes in hypersaline cyanobacterial mats

An unidentified filamentous purple bacterium, probably belonging to a new genus or even a new family, is found in close association with the filamentous, mat-forming cyanobacterium Microcoleus chthonoplastes in a hypersaline pond at Guerrero Negro, Baja California Sur, Mexico, and in Solar Lake, Sinai, Egypt. This organism is a gliding, segmented trichome, 0.8-0.9 micrometer wide. It contains intracytoplasmic stacked lamellae which are perpendicular and obliquely oriented to the cell wall, similar to those described for the purple sulfur bacteria Ectothiorhodospira. These bacteria are found inside the cyanobacterial bundle, enclosed by the cyanobacterial sheath. Detailed transmission electron microscopical analyses carried out in horizontal sections of the upper 1.5 mm of the cyanobacterial mat show this cyanobacterial-purple bacterial association at depths of 300-1200 micrometers, corresponding to the zone below that of maximal oxygenic photosynthesis. Sharp gradients of oxygen and sulfide are established during the day at this microzone in the two cyanobacterial mats studied. The close association, the distribution pattern of this association and preliminary physiological experiments suggest a co-metabolism of sulfur by the two-membered community. This probable new genus of purple bacteria may also grow photoheterotrophically using organic carbon excreted by the cyanobacterium. Since the chemical gradients in the entire photic zone fluctuate widely in a diurnal cycle, both types of metabolism probably take place. During the morning and afternoon, sulfide migrates up to the photic zone allowing photoautotrophic metabolism with sulfide as the electron donor. During the day the photic zone is highly oxygenated and the purple bacteria may either use oxidized species of sulfur such as elemental sulfur and thiosulfate in the photoautotrophic mode or grow photoheterotrophically using organic carbon excreted by M. chthonoplastes. The new type of filamentous purple sulfur bacteria is not available yet in pure culture, and its taxonomical position cannot be fully established. This organism is suggested to be a new type of gliding, filamentous, purple phototroph.

NASA Discipline Exobiology↗
NASA NTRSDate not supplied

Polar Vortex Outbreak Air Transport: Observation using Satellite IR Sounder Derived Ozone Product and Comparison with Model

The Single Field of View (SFOV) Sounder Atmospheric Products (SiFSAP) derived from Cross-track Infrared Sounder (CrIS) on SNPP and JPSS have a spatial resolution ( ~14.5 km) better than most global weather and climate models. Most recent significant improvement in the quality of these products enables us to use these high-resolution observation-based sounding data for weather studies and model evaluation. The aim of this study is to explore the value to use these SFOV products for studying the dynamic transport associated with polar vortex outbreak. In a few cases studies, we used SiFSAP products, especially ozone, as well as the data of wind, geopotential height (GPH) and potential velocity (PV) from the fifth-generation ECMWF reanalysis (ERA5) data, to analyze the variation of total ozone, relative humidity and ozone in different layers, as well as their correlation with GPH and PV. Some comparison of the retrieved temperature and water vapor with ERA5 data, and ozone with the Ozone Mapping and Profiler Suite (OMPS) measurements have also been made. It is found (1) the transport of O3-riched polar air accompanying the polar vortex breakup to lower latitude and lower atmosphere, and (2) the transport path of O3 agreeing well with the path of polar cold air (illustrated using the retrieved RH, wind fields and GPH). These results demonstrate the 3-D structure of O3 distribution as derived from CrIS measurements provides some insights of the cold air transport, and can be used to track the dynamic transport of polar cold air following the outbreak of polar vortex. The observed enhancement of O3 following the polar vortex outbreak also suggests some possible linkage between the tropospheric cold air advected with stratospheric air source.

Xiaozhen Xiong↗
NASA NTRS1988

Carrier phases for iodine in the Allende meteorite and their associated Xe-129(r)/I-127 ratios - A laser microprobe study

This paper presents the results of a study of the carrier phases of iodine in the Allende meteorite and their associated Xe-129(r)/I-127 ratios, obtained using a new high-sensitivity low-blank mass spectrometer coupled with a low-blank laser extraction system. Two types of experiments were performed: a survey of the Xe-129(r) amounts in unirradiated specimens of fine-grained assemblages and individual coarse mineral grains, and a study of the relationship between chlorine and iodine in irradiated samples of the inclusions, in which the Xe-129(r)/I-127 ratios were determined for various minerals. As a by-product of these measurements, the Ar-40/Ar-39 ages were obtained along with some results on trapped Xe components. A schematic diagram of the new mass spectrometer system is included.

Kirschbaum, C.↗
NASA NTRS1998

Study of the Effects of Photometric Geometry on Spectral Reflectance Measurements

The objective of this research is to investigate how the spectrophotometric properties of planetary surface materials depend on photometric geometry by refining and applying radiative transfer theory to data obtained from spacecraft and telescope observations of planetary surfaces, studies of laboratory analogs, and computer simulations. The goal is to perfect the physical interpretation of photometric parameters in the context of planetary surface geological properties and processes. The purpose of this report is to document the research achievements associated with this study.

Helfenstein, Paul↗
NASA NTRS2010

Hazards Due to Overdischarge in Lithium-ion Cylindrical Cells in Multi-cell Configurations

Lithium-ion cells in the cylindrical Commercial-off-the-shelf 18650 design format were used to study the hazards associated with overdischarge. The cells in series or in parallel configurations were subjected to different conditions of overdischarge. The cells in parallel configurations were all overdischarged to 2.0 V for 75 cycles with one cell removed at 25 cycles to study the health of the cell. The cells in series were designed to be in an unbalanced configuration by discharging one cell in each series configuration before the start of test. The discharge consisted of removing a pre-determined capacity from the cell. This ranged from 50 to 150 mAh removal. The cells were discharged down to a predetermined end-of-discharge voltage cutoff which allowed the cell with lower capacity to go into an overdischarge mode. The cell modules that survived the 75 cycles were subjected to one overvoltage test to 4.4 V/cell.

Jeevarajan, Judith↗