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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Method for conducting in situ high-temperature digital image correlation with simultaneous synchrotron measurements under thermomechanical conditions

This work presents a novel method of obtaining in situ strain measurements at high temperature by simultaneous digital image correlation (DIC), which provides the total strain on the specimen surface, and synchrotron x-ray diffraction (XRD), which provides lattice strains of crystalline materials. DIC at high temperature requires specialized techniques to overcome the effects of increased blackbody radiation that would otherwise overexpose the images. The technique presented herein is unique in that it can be used with a sample enclosed in an infrared heater, remotely and simultaneously with synchrotron XRD measurements. The heater included a window for camera access, and the light of the heater lamps is used as illumination. High-temperature paint is used to apply a random speckle pattern to the sample to allow the tracking of displacements and the calculation of the DIC strains. An inexpensive blue theatrical gel filter is used to block interfering visible and infrared light at high temperatures. This technique successfully produces properly exposed images at 870 °C and is expected to perform similarly at higher temperatures. The average strains measured by DIC were validated by an analytical calculation of the theoretical strain. Simultaneous DIC and XRD strain measurements of Inconel 718 (IN718) tensile test specimens were performed under thermal and mechanical loads and evaluated. Finally, this approach uses the fact that with DIC, the total strain is measured, including plastic strain, while with XRD, only elastic strain is captured. The observed differences were discussed with respect to the effective deformation mechanisms.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Development of Ambient Mass Spectrometry Rapid Analysis Methods for Trace Inorganics

Ambient mass spectrometry is being investigated as a new method for rapidly characterizing trace inorganic species, including nuclear materials. SRNL is currently developing electrospray ionization (ESI) and paper spray ionization (PSI) methods for mass spectrometry for the detection of trace inorganic compounds JEOL AccuTOF™-DART ® LP 4G mass spectrometer. Sample analysis generates a complex three-dimensional data set with 10 2 -10 3 individual mass spectra spread temporally. To improve the quality and ease of data extraction from this amount of information, a simple data analysis pipeline written in R/R Studio has been improved and expanded upon. Specifically, the software now has header inputs to set base input/output filenames, isotopes of interest, and a list of concentrations analyzed on the instrument. Using list-based structures to enable batch processing of many concentrations at once, it then loads each file, extracts the relevant intensities for masses of interest from each spectrum, and iterates through each concentration to generate graphs of internal standard & analyte correlations, measured isotope ratios, and total ion chromatograms. It then filters the data to remove points at background levels or at the detector saturation limit. Using this filtered data, the pipeline re-creates the graphs to reveal high-quality information from a low-quality raw dataset. All graphs of the R software then output to PowerPoint format. Additionally, faster 3D visualization functionality was added to the pipeline for viewing the entire data file produced by the instrument as an intensity map. With these data analysis tools ready, samples of strontium nitrate/yttrium nitrate as an analyte/internal standard combination were measured on the AccuTOF. From the filtered data, calibration curves were prepared and limits of detection (LOD) of 1 ppb for ESI-MS and 20 ppb for PSI-MS were obtained. The quality available from the calibration curves and the low limits of detection demonstrate the value of the instrument/analysis pipeline system in characterizing trace inorganics.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

C136A and C138A Report of Analysis

In this work the isotopic ratios and weight percentages of 238 Pu, 239 Pu, 240 Pu, 241 Pu and 242 Pu were determined using Isotope Dilution Mass Spectrometry. Two samples of C136A and C138A were sent to the Analytical Research laboratories by the National Nuclear Security Administration Nuclear Reference Material Program. The four samples were dissolved in concentrated hydrochloric acid. From the parent solutions, eight aliquots were taken, diluted, spiked with 244 Pu and submitted to separations. After the samples were separated, they were analyzed using Multicollector Inductively Coupled Plasma Mass Spectrometry. Along with the samples, two C126A Quality Control Samples were analyzed each day. Mass bias standards were also analyzed at the beginning, during and at the end of the analysis. GUM Workbench Pro software Version 2.4.1.406 was used to calculate the isotopic ratios relative to 239 Pu, and total Pu mass and the correlated expanded uncertainties.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2018

The 2.4 μ m Galaxy Luminosity Function as Measured Using WISE . III. Measurement Results

The Widefield Infrared Survey Explorer (WISE) satellite surveyed the entire sky multiple times in four infrared wavelengths (3.4, 4.6, 12, and 22 μm). The unprecedented combination of coverage area and depth gives us the opportunity to measure the luminosity function (LF) of galaxies, one of the fundamental quantities in the study of them, at 2.4 μm to an unparalleled level of formal statistical accuracy in the near-infrared. The big advantage of measuring LFs at wavelengths in the window of ≈2–3.5 μm is that it correlates more closely to the total stellar mass in galaxies than others. In this paper we report on the parameters of the 2.4 μm LF of galaxies obtained from applying the spectro-luminosity-functional-based methods to datasets from the previous papers in this series using the mean and covariance of 2.4 μm normalized spectral energy distributions (SEDs) from our previous work. In terms of the single Schechter function parameters evaluated at the present epoch, the combined result is: ${\phi }_{\star }=5.8\,\pm [{0.3}_{\mathrm{stat}},{0.4}_{\mathrm{sys}}]\times {10}^{-3}\,{\mathrm{Mpc}}^{-3}$, ${L}_{\star }=6.4\pm [{0.1}_{\mathrm{stat}},{0.3}_{\mathrm{sys}}]\times {10}^{10}\,{L}_{2.4\mu {\rm{m}}\odot }$ (M$_{\star}$ = -21.67 ± [0.02 stat , 0.05 sys ] AB mag), and $α$ = -1.050 ± [0.004 stat , 0.04 sys ]. The high statistical accuracy comes from combining public redshift surveys with the wide coverage from WISE, and the unevenness in statistical accuracy is a result of our efforts to work around biases of uncertain origin that affect resolved and marginally resolved galaxies. With further refinements, the techniques applied in this work promise to advance the study of the SED of the universe.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Short-duration solar microwave bursts and associated soft X-ray emission

Two hundred and fifty-nine short-duration microwave (15.4 GHz) bursts which occurred during the period of January 1968 to March 1970 were correlated with possible soft X-ray (2-12 A) flares occurring simultaneously. Sixty-six percent of the microwave bursts which were observed during periods of soft X-ray data coverage had associated soft X-ray flares. A study of an index of impulsiveness of the microwave flares failed to show a separation of the events into subclasses which could be attributed to distinctly different physical mechanisms. A weak (0.43) correlation was found between the intensities of the microwave and X-ray flares. A very weak (0.15) and statistically questionable correlation was found between the total energy released in these two energy ranges. Two models for the electron acceleration mechanism are discussed.

Spangler, S. R.↗
NASA NTRS1973

Detection of moisture and moisture related phenomena from Skylab

The author has identified the following significant results. Correlations between the S-194 antenna temperature and soil moisture have been obtained for three sets of data; one for Skylab 2 and two for Skylab 3. The best correlations were obtained for the surface to one inch depth in two cases and for the surface to two inches for the third case. Correlation coefficients for the surface to one inch depth were -0.98, -0.95, and -0.82. The lowest correlation coefficient was obtained with total soil moisture variations less than 4% across the test site.

Eagleman, J. R.↗
NASA NTRS1978

Emittance and absorptance of NASA ceramic thermal barrier coating system

Spectral emittance measurements were made on a two-layer ceramic thermal barrier coating system consisting of a metal substrate, a NiCrAly bond coating and a yttria-stabilized zirconia ceramic coating. Spectral emittance data were obtained for the coating system at temperatures of 300 to 1590 K, ceramic thickness of zero to 0.076 centimeter, and wavelengths of 0.4 to 14.6 micrometers. The data were transformed into total hemispherical emittance values and correlated with respect to ceramic coating thickness and temperature using multiple regression curve fitting techniques. The results show that the ceramic thermal barrier coating system is highly reflective and significantly reduces radiation heat loads on cooled gas turbine engine components. Calculation of the radiant heat transfer within the nonisothermal, translucent ceramic coating material shows that the gas-side ceramic coating surface temperature can be used in heat transfer analysis of radiation heat loads on the coating system.

Liebert, C. H.↗
NASA NTRS1978

Modeling aerosol losses and clothing effects in fires

The described modification of a physiochemical fire model predicts physical effects in clothed humans exposed to elevated temperatures as well as gas and aerosol concentrations in the atmosphere of an aerospace vehicle. The modifications involve the reduction in aerosol concentrations caused by settling and some improvements in dealing with mass and heat transfer effects. Predicted skin temperatures are found to be within 2 C of experimental values for the cases studied, and model predictions of total body enthalpy seem to correlate with symptomology observed experimentally.

Cagliostro, D. E.↗
NASA NTRS1979

Remote sensing of phytoplankton density and diversity in Narragansett Bay using an airborne fluorosensor

An aircraft-borne remote system is presented that utilizes narrow-band light from multiple dye lasers to excite selected algae photopigments and then measures the resultant flourescence emitted from chlorophyll a at 685 nm. Tests were conducted with both pure and mixed cultures of marine algae from a series of field tests taken from piers and bridges of Narragansett Bay, and a prototype remote fluorosensor was flown over the Bay during the 1978 winter-spring diatom bloom. Remote fluorescence obtained at hover points over sea-truth stations showed correlations with in situ fluorescence, total chlorophyll a, and cell count. It was concluded that the ratio of remote fluorescence to direct chlorophyll a concentration was less variable than expected, and the distribution of total chlorophyll a between two major photoplankton color groups showed three distinct areas, within the Bay, of green and golden-brown species.

Farmer, F. H.↗
NASA NTRS1982

Workshop rationale

The problems involved in processing remotely sensed data are defined within the contex of the total information system structure. The correlation of various data sets through georeferencing and cataloging is emphasized along with geometric rectification. The sources and types of possible geometric errors are outlined.

Billingsley, F. C.↗
NASA NTRS1987

A statistical analysis of the Einstein normal galaxy sample. III - Radio and X-ray properties of elliptical and S0 galaxies

Radioastronomy, optical and X-ray data were used to probe the cause of high X-ray luminosities of 28 radio-quiet elliptical galaxies (RQE) and S0 galaxies previously scanned by the Einstein Observatory. Comparisons were made with similar data on double-lobed 3CR galaxies. Radio luminosities were highly correlated with the X-ray luminosities, agreeing with models of radio nuclear sources in early-type galaxies as accreting compact objects. Additionally, 3CR galaxies seemed to be large-scale versions of normal RQE. The significance of interstellar medium/intracluster medium interactions for high correlations between the core and total radio power from X-ray emitting galaxies is discussed.

Fabbiano, G.↗
NASA NTRS1989

An evaluation of imaging spectrometry for estimating forest canopy chemistry

High spectral resolution Airborne Imaging Spectrometer (AIS) data were acquired over 20 well-studied Wisconsin forest sites to evaluate the potential of remote sensing for estimating forest canopy chemistry. Intensive nutrient cycling research in these forests demonstrates that canopy lignin content is strongly related to measured annual nitrogen mineralization at the undisturbed sites and may serve as an accurate index for nitrogen cycling rates. Ground measurements were made of foliar biomass and canopy nitrogen and lignin content, the latter within two weeks of the AIS overflight. The spectral data were transformed using derivative techniques modified from laboratroy spectroscopy. Stepwise regression assisted in determining combinations of wavelengths most highly correlated with canopy chemistry and biomass. Strong correlations between AIS data and total canopy lignin content in deciduous forests and canopy lignin concentration (total lignin/biomass) in both deciduous and coniferous stands indicate that imaging spectrometry can be used to estimate canopy lignin content and, from that, the spatial distribution of annual nitrogen mineralization rates.

Wessman, Carol A.↗
NASA NTRS1992

A verified design of a fault-tolerant clock synchronization circuit: Preliminary investigations

Schneider demonstrates that many fault tolerant clock synchronization algorithms can be represented as refinements of a single proven correct paradigm. Shankar provides mechanical proof that Schneider's schema achieves Byzantine fault tolerant clock synchronization provided that 11 constraints are satisfied. Some of the constraints are assumptions about physical properties of the system and cannot be established formally. Proofs are given that the fault tolerant midpoint convergence function satisfies three of the constraints. A hardware design is presented, implementing the fault tolerant midpoint function, which is shown to satisfy the remaining constraints. The synchronization circuit will recover completely from transient faults provided the maximum fault assumption is not violated. The initialization protocol for the circuit also provides a recovery mechanism from total system failure caused by correlated transient faults.

Miner, Paul S.↗
NASA NTRS1992

Retrieval of total precipitable water over high-latitude regions using radiometric measurements near 90 and 183 GHz

Radiometric measurements at 90 GHz and three sideband frequencies near the peak water vapor absorption line of 183.3 GHz were made with Advanced Microwave Moisture Sounder (AMMS) aboard the NASA DC-8 aircraft during the Global Aerosol Backscatter Experiment (GLOBE) mission over the Pacific Ocean in November 1989. Some of the measurements over the high-latitude regions (greater than 50 deg N or 50 deg S) were analyzed for the retrieval of total precipitable water less than 0.5 g/sq cm both over land and ocean surfaces. The results show that total precipitable water from a relatively dry atmosphere could be estimated with high sensitivity from these radiometric measurements. The retrieved values over ocean surface show a decrease toward the polar region as expected. The retrieved total precipitable water over land correlates positively with the aircraft radar altitude. This positive correlation is expected because the aircraft radar altitude provides a measure of atmospheric water vapor burden above the surface. Retrieved high reflectivities over land surface at 90 GHz and 183 GHz are presumably related to snow cover on the ground. This suggests that radiometric measurements at these frequencies could be used to map snow at high-latitude regions.

Wang, J. R.↗
NASA NTRS1992

Green and non-green callus induction from excised rice (Oryza sativa) embryos: effects of exogenous plant growth regulators

Calli were induced either from excised rice embryos or from whole seeds in the presence of 1 to 5 mg l-1 NAA. After 12 days of culture, calli were induced only from excised rice embryos. We found that excised embryos accumulated NAA up to 6 times higher concentration than did whole seeds. In the presence of 1 to 5 mg l-1 NAA and 2 to 10 mg l-1 kinetin, chlorophyllous calli were induced from excised rice embryos. Chlorophyll contents in the callus tissue increased with increasing kinetin concentration while percent callus induction decreased. The total chlorophyll content was linearly correlated with the ratio of kinetin to NAA in the medium.

NASA Discipline Number 40-50↗
NASA NTRS2001

Spatial orientation and balance control changes induced by altered gravitoinertial force vectors

To better understand the mechanisms of human adaptation to rotating environments, we exposed 19 healthy subjects and 8 vestibular-deficient subjects ("abnormal"; four bilateral and four unilateral lesions) to an interaural centripetal acceleration of 1 g (resultant 45 degrees roll-tilt of 1.4 g) on a 0.8-m-radius centrifuge for periods of 90 min. The subjects sat upright (body z-axis parallel to centrifuge rotation axis) in the dark with head stationary, except during 4 min of every 10 min, when they performed head saccades toward visual targets switched on at 3- to 5-s intervals at random locations (within +/- 30 degrees) in the earth-horizontal plane. Eight of the normal subjects also performed the head saccade protocol in a stationary chair adjusted to a static roll-tilt angle of 45 degrees for 90 min (reproducing the change in orientation but not the magnitude of the gravitoinertial force on the centrifuge). Eye movements, including voluntary saccades directed along perceived earth- and head-referenced planes, were recorded before, during, and immediately after centrifugation. Postural center of pressure (COP) and multisegment body kinematics were also gathered before and within 10 min after centrifugation. Normal subjects overestimated roll-tilt during centrifugation and revealed errors in perception of head-vertical provided by directed saccades. Errors in this perceptual response tended to increase with time and became significant after approximately 30 min. Motion-sickness symptoms caused approximately 25% of normal subjects to limit their head movements during centrifugation and led three normal subjects to stop the test early. Immediately after centrifugation, subjects reported feeling tilted 10 degrees in the opposite direction, which was in agreement with the direction of their earth-referenced directed saccades. Postural COP, segmental body motion amplitude, and hip-sway frequency increased significantly after centrifugation. These postural effects were short-lived, however, with a recovery time of several postural test trials (minutes). There were also asymmetries in the direction of postcentrifugation COP and head tilt which depended on the subject's orientation during the centrifugation adaptation period (left ear or right ear out). The amount of total head movements during centrifugation correlated poorly or inversely with postcentrifugation postural stability, and the most unstable subject made no head movements. There was no decrease in postural stability after static tilt, although these subjects also reported a perceived tilt briefly after return to upright, and they also had COP asymmetries. Abnormal subjects underestimated roll-tilt during centrifugation, and their directed saccades revealed permanent spatial distortions. Bilateral abnormal subjects started out with poor postural control, but showed no postural decrements after centrifugation, while unilateral abnormal subjects had varying degrees of postural decrement, both in their everyday function and as a result of experiencing the centrifugation. In addition, three unilateral, abnormal subjects, who rode twice in opposite orientations, revealed a consistent orthogonal pattern of COP offsets after centrifugation. These results suggest that both orientation and magnitude of the gravitoinertial vector are used by the central nervous system for calibration of multiple orientation systems. A change in the background gravitoinertial force (otolith input) can rapidly initiate postural and perceptual adaptation in several sensorimotor systems, independent of a structured visual surround.

Clinical Trial↗
NASA NTRS1993

Effect of exercise training on cardiopulmonary baroreflex control of forearm vascular resistance in humans

We studied the stimulus-response characteristics of cardiopulmonary baroreflex control of forearm vascular resistance (FVR) in four groups of male volunteer subjects: i) unfit, ii) physically fit, iii) before and after 10 wk of endurance training (chronic blood volume expansion), and iv) before and after acute blood volume expansion. We assessed the relationship between reflex stimulus, i.e., changes in central venous pressure and response, i.e., FVR, during unloading of cardiopulmonary mechanoreceptors with lower body negative pressure (LBNP, 0 to -20 mm Hg). The slope of the linear relationship between FVR and CVP, the index of the responsiveness of this baroreflex, was significantly diminished (> 50%) in the fit subjects compared with the unfit. The slope of the FVR-CVP relationship was inversely correlated with the subject's total blood volume, suggesting that blood volume expansion was related to the attenuated CP baroreflex. In the exercise training study, maximal oxygen consumption and blood volume increased following 10 wk of endurance training (N = 14) but were unchanged in the time control group (N = 7). The slope of the FVR-CVP relationship was significantly reduced (32%) following 10 wk of training but was unchanged in the time control group. The reduction in slope of the FVR-CVP relationship was inversely related to the increase in blood volume associated with exercise training. Acute blood volume expansion 8 ml.kg-1 body weight with 5% human serum albumin solution) significantly reduced the slope of the FVR-CVP relationship. These data support the hypothesis that the attenuated forearm vascular reflex in physically fit individuals is related to a training-induced hypervolemia.(ABSTRACT TRUNCATED AT 250 WORDS).

Review↗