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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Infant burn injuries related to water heating for powdered infant formula preparation

Guidance for preparing powdered infant formula (PIF) helps to ensure it meets the nutritional needs of infants and is safe to consume. Among safety concerns is Cronobacter sakazakii contamination which can lead to serious infections and death. PIF preparation guidance varies; there is a lack of consensus on whether there is a need to boil water to inactivate potential Cronobacter and for how long to let the water cool before reconstitution. We sought to quantify the burden of burn injuries among infants related to water heating for PIF preparation. Estimating this burden may help inform preparation recommendations. Burn injuries among infants <18 months of age were identified from 2017 to 2019 National Electronic Injury Surveillance System data collected from sampled hospital emergency departments. Injuries were classified as related to PIF water heating, potentially related to PIF water heating but with undetermined causation, related to other infant feeding aspects, or unrelated to infant formula or breast milk feeding. Unweighted case counts for each injury classification were determined. Across sampled emergency departments, 7 PIF water heating injuries were seen among the 44,395 injuries reported for infants <18 months. No reported PIF water heating injuries were fatal, but 3 required hospitalization. Another 238 injuries potentially related to PIF water heating but with undetermined causation were also seen. Preparation guidance should consider both the potential risk for Cronobacter infection and the potential risk for burns.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades

X-ray observations of low-mass stars in open clusters are critical to understanding the dependence of magnetic activity on stellar properties and their evolution. Praesepe and the Hyades, two of the nearest, most-studied open clusters, are among the best available laboratories for examining the dependence of magnetic activity on rotation for stars with masses ≲1 M ⊙ . We present an updated study of the rotation–X-ray activity relation in the two clusters. We updated membership catalogs that combine pre-Gaia catalogs with new catalogs based on Gaia Data Release 2. The resulting catalogs are the most inclusive ones for both clusters: 1739 Praesepe and 1315 Hyades stars. We collected X-ray detections for cluster members, for which we analyzed, re-analyzed, or collated data from ROSAT, the Chandra X-ray Observatory, the Neil Gehrels Swift Observatory, and XMM-Newton. We have detections for 326 Praesepe and 462 Hyades members, of which 273 and 164, respectively, have rotation periods—an increase of 6× relative to what was previously available. We find that at ≈700 Myr, only M dwarfs remain saturated in X-rays, with only tentative evidence for supersaturation. We also find a tight relation between the Rossby number and fractional X-ray luminosity L X /L bol in unsaturated single members, suggesting a power-law index between –3.2 and –3.9. Lastly, we find no difference in the coronal parameters between binary and single members. These results provide essential insight into the relative efficiency of magnetic heating of the stars' atmospheres, thereby informing the development of robust age-rotation-activity relations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

The Role of Inner H ι Mass in Regulating the Scatter of the Mass–Metallicity Relation

We use 789 disk-like, star-forming galaxies (with 596 H ι detections) from H ι follow-up observations for the SDSS-IV MaNGA survey to study the possible role of inner H ι gas in causing secondary dependences in the mass–gas-phase metallicity relation. We use the gas-phase metallicity derived at the effective radii of the galaxies. We derive the inner H ι mass within the optical radius, but also use the total H ι mass and star formation rate (SFR) for a comparison. We confirm the anticorrelation between the total H ι mass and gas-phase metallicity at fixed stellar mass, but the anticorrelation is significantly strengthened when the total H ι mass is replaced by the inner H ι mass. Introducing a secondary relation with the inner H ι mass can produce a small but noticeable decrease (16%) in the scatter of the mass–gas-phase metallicity relation, in contrast to the negligible effect with the SFR. The correlation with the inner H ι mass is robust when using different diagnostics of metallicity, but the correlation with SFR is not. The correlation with the inner H ι mass becomes much weaker when the gas-phase metallicity is derived in the central region instead of at the effective radius. These results support the idea that the scatter in the mass–metallicity relation is regulated by gas accretion, and not directly by the SFR, and stress the importance of deriving the gas mass and the metallicity from roughly the same region. The new relation between inner H ι mass and gas-phase metallicity will provide new constraints for chemical and galaxy evolution models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Correlations between the Neutron Star Mass–Radius Relation and the Equation of State of Dense Matter

We develop an analytic method of inverting the Tolman–Oppenheimer–Volkoff relations to high accuracy. In principle, a specified energy density–pressure relation gives a unique mass–radius (M–R) relation and vice versa. Our method is developed from the strong correlations that are shown to exist between the neutron star mass–radius curve and the equation of state (EOS) or pressure–energy density relation. Selecting points that have masses equal to fixed fractions of the maximum mass, we find a semi-universal power-law relation between the central energy densities, pressures, sound speeds, chemical potentials, and number densities of those stars, with the maximum mass and the radii of one or more fractional maximum mass points. Rms fitting accuracies, for EOSs without large first-order phase transitions, are typically 0.5% for all quantities at all mass points. The method also works well, although less accurately, in reconstructing the EOS of hybrid stars with first-order phase transitions. These results permit, in effect, an analytic method of inverting an arbitrary M–R curve to yield its underlying EOS. We discuss applications of this inversion technique to the inference of the dense matter EOS from measurements of neutron star masses and radii as a possible alternative to traditional Bayesian approaches.

Bayesian statistics↗
NASA NTRS1972

A study of the variations in the thermosphere related to solar activity.

Densities derived from the drag of five artificial satellites and covering the time interval from 1958 to 1971 have been used to study the variations in the thermosphere arising from changes in solar activity. Exospheric temperatures derived from the densities by means of atmospheric models have been related to the 10.7-cm solar flux, in which the active-area component had been separated from the slow-varying clear-disk component by means of a relation between the flux and sunspot areas. When the day-to-day (27-day) variation is suppressed, the remaining slow temperature variation appears to be linearly related to the clear-disk flux component. If we also relate linearly the day-to-day temperature variations with the day-to-day variations of the flux, we find that the regression coefficient changes from 1 K at sunspot maximum to 2 K at low solar activity; a nearly constant coefficient is obtained by relating the temperature variations to the ratio of the active-area component to the clear-disk component of the flux.

Jacchia, L. G.↗
NASA NTRS1975

Relative abundance of proton to helium nuclei in solar cosmic ray events

A statistical study of the relative abundance of proton to alpha particles at equal energy per nucleon has been carried out on the basis of some hundred solar particle events in the energy range 6-20 MeV/nuc. A small qualitative effect of the coronal propagation has been found for events associated with solar flares away from the observer 'preferred connection region' (20-80 deg W from the central meridian). The variation of the relative abundance of the proton to alpha particle at ejection is analyzed using events for which the coronal transport is minimum. It is found that micro events characterized by small proton intensity, little or no scattering in interplanetary medium and little or no trapping in the corona has an abundance of He-4 of 5-30% relative to proton. Those events frequently display a very high He-3 abundance from 30 to 150% relatively to He-4. For larger particle events, the alpha abundance decreases following a relation which is not valid for flare-associated events that accelerate particles to relativistic energies.

Van Hollebeke, M. A. I.↗
NASA NTRS1979

Precise relative location estimation from satellite laser observations

Laser data from the Greenbelt, Bermuda, and Grand Turk Island tec tracking stations, and from observation at Patrick Air Force Base were used in an experiment to determine precise inter-station baselines and relative heights in short orbital arcs of no more than 12 minutes duration. The relative locations obtained are sensitive to reasonable variations in the gravity field to less than 15 cm in inter-station baseline and less than 35 cm in relative height. The formal standard deviations for range measurements at the observed 7 cm noise level are less than 10 cm for either baseline or relative height determinations from the twenty-arc combination solution. The method of data analysis is described, the baseline and relative height results are presented, and gravity model dependence is considered.

Dunn, P. J.↗
NASA NTRS1979

A possible closure relation for heat transport in the solar wind

The objective of the present paper is to search for an empirical closure relation for solar wind heat transport that applies to a microscopic scale. This task is approached by using the quasi-linear wave-particle formalism proposed by Perkins (1973) as a guide to derive an equation relating the relative drift speed between core-electron and proton populations to local bulk flow conditions. The resulting relationship, containing one free parameter, is found to provide a good characterization of Los Alamos Imp electron data measuring during the period from March 1971 through August 1974. An empirical closure relation is implied by this result because of the observed proportionality between heat flux and relative drift speed.

Feldman, W. C.↗
NASA NTRS1981

The visual surface brightness relation and the absolute magnitudes of RR Lyrae stars. I - Theory

A theoretical relation analogous to the Barnes-Evans relation between stellar surface brightness and V-R color is derived which is applicable to the temperatures and gravities appropriate to RR Lyrae stars. Values of the visual surface brightness and V-R colors are calculated for model stellar atmospheres with effective temperatures between 6000 and 8000 K, log surface gravities from 2.2 to 3.5, and A/H anbundance ratios from -0.5 to -3.0. The resulting relation is found to be in reasonable agreement with the empirical relation of Barnes, Evans and Moffet (1978), with, however, small sensitivities to gravity and metal abundance. The relation may be used to derive stellar angular diameters from (V,R) photometry and to derive radii, distances, and absolute magnitudes for variable stars when combined with a radial velocity curve. The accuracies of the radii and distances (within 10%) and absolute magnitudes (within 0.25 magnitudes) compare favorably with those of the Baade-Wesselink method currently in use.

Manduca, A.↗
NASA NTRS1982

The local dispersion relation for magneto-atmospheric waves

The local dispersion relation for magneto-atmospheric waves is discussed in terms of the linearized theory of waves in a plane-stratified, inviscid, perfectly conducting atmosphere under uniform gravity. The normally used local dispersion relation is demonstrated to not be unique, depending instead on the order of derivation from the fundamental first-order perturbation equations of continuity, momentum, energy, and induction. Furthermore, it is shown that the local dispersion relation predicts that the cutoff frequency decreases with increasing magnetic field strength, while the WKB approximation method projects an increase in the cutoff frequency with increasing magnetic field strength. A new form of the local dispersion relation is developed, and consideration is given to the special case of a global dispersion relation in conditions of an isothermal atmosphere with a horizontal magnetic field.

Thomas, J. H.↗
NASA NTRS1983

Solar related waves in the Venusian atmosphere from the cloud tops to 100 km

A quasi-linear diagnostic model using observed solar-related temperatures and a specified solar mean circulation and surface structure to find the solar-related circulation above the clouds of Venus is presented. Despite the greater dependence of model-derived, solar-related circulation on the mean flow than is the case for terrestrial tides, as well as the uncertainty concerning this mean flow, significant conclusions are drawn for the solar-related circulation and thermal structure of Venus. An anomalously large response is found in the polar regions, due to the model's requirement of a process such as dissipation which will act as a major sink for momentum. Dissipation is specified in the model as Rayleigh friction with an unknown free parameter coefficient. In view of this, dissipation is either very efficient by terrestrial standards and accompanied by small solar-related circulation, or similar to that of earth and possessed of a circulation large enough to have an impact on the mean circulation.

Elson, L. S.↗
NASA NTRS1986

Generalized parity relations for large space structures with uncertain parameters

The generalized parity relations method is a technique that can be used to detect sensor and actuator failures on a large space structure. A model of a grid structure was used to evaluate the performance of these relations. It shows their relative sensitivity to modeling errors. A method using sensor outputs and actuator inputs is required for the design of the generalized parity relations. Three different estimators are studied. The last estimator can generate relations optimized for the detection of a particular failure which are interesting when the level of sensor noise is high.

Dutilloy, J. R.↗
NASA NTRS1987

The core mass-radius relation for giants - A new test of stellar evolution theory

It is demonstrated here that the measurable properties of systems containing degenerate dwarfs can be used as a direct test of the core mass-radius relation for moderate-mass giants if the final stages of the loss of the envelope of the progenitor giant occurred via stable critical lobe overflow. This relation directly probes the internal structure of stars at a relatively advanced evolutionary state and is only modestly influenced by adjustable parameters. The measured properties of six binary systems, including such diverse systems as Sirius and Procyon and two millisecond pulsars, are utilized to derive constraints on the empirical core mass-radius relation, and the constraints are compared to the theoretical relation. The possibility that the final stages of envelope ejection of the giant progenitor of Sirius B occurred via critical lobe overflow in historical times is considered.

Joss, P. C.↗
NASA NTRS1987

The surface-brightness-effective-size relation for elliptical galaxies in the cores of clusters

Surface photometry of 372 elliptical galaxies has been performed using CCD images of the centers of 97 nearby rich Abell clusters. The strong correlation between surface brightness and effective size, originally found by Kormendy (1977), is clear in the data. Brightest cluster galaxies show much less scatter about the mean relation defined by these data than do lower-luminosity cluster ellipticals, and the slope of the relation is shallower for the brightest galaxies; these two results are tentative, however, because of uncertain selection and environmental effects. When combined with published central velocity dispersions, the photometry yields a relation for brightest cluster galaxies that is in good agreement with the mean relation for elliptical galaxies found by Djorgovski and Davis (1987). Use of the surface-brightness/scale-length relation to measure the lookback luminosity evolution of the stellar content in galaxies is promising.

Hoessel, J. G.↗
NASA NTRS1988

Learning dominance relations in combinatorial search problems

Dominance relations commonly are used to prune unnecessary nodes in search graphs, but they are problem-dependent and cannot be derived by a general procedure. The authors identify machine learning of dominance relations and the applicable learning mechanisms. A study of learning dominance relations using learning by experimentation is described. This system has been able to learn dominance relations for the 0/1-knapsack problem, an inventory problem, the reliability-by-replication problem, the two-machine flow shop problem, a number of single-machine scheduling problems, and a two-machine scheduling problem. It is considered that the same methodology can be extended to learn dominance relations in general.

Yu, Chee-Fen↗
NASA NTRS1989

Monotonically improving approximate answers to relational algebra queries

We present here a query processing method that produces approximate answers to queries posed in standard relational algebra. This method is monotone in the sense that the accuracy of the approximate result improves with the amount of time spent producing the result. This strategy enables us to trade the time to produce the result for the accuracy of the result. An approximate relational model that characterizes appromimate relations and a partial order for comparing them is developed. Relational operators which operate on and return approximate relations are defined.

Smith, Kenneth P.↗
NASA NTRS1990

Current plate velocities relative to the hotspots incorporating the NUVEL-1 global plate motion model

The NUVEL-1 model of current global relative plate velocities is presently incorporated into HS2-NUVEL1, a global model for plate velocities relative to hotspots; the results thus obtained are compared with those of the AM1-2 model of hotspot-relative plate velocities. While there are places in which plate velocities relative to the hotspots differ between HS2-NUVEL1 and AM1-2 by tens of degrees in direction and 15 mm/yr in speed, the hotspot Euler vectors differ with 95 percent confidence only for the Arabian and Indian plates. Plates attached to subducting slabs move faster relative to the hotspots than do plates without slabs.

Gripp, Alice E.↗
NASA NTRS1991

Control system failure monitoring using generalized parity relations

Many applications require that a control system must be tolerant to the failure of its components. This is especially true for large space-based systems that must work unattended and with long periods between maintenance. Fault tolerance can be obtained by detecting the failure of the control system component, determining which component has failed, and reconfiguring the system so that the failed component is isolated from the controller. Component failure detection experiments that were conducted on an experimental space structure, the NASA Langley Mini-Mast are presented. Two methodologies for failure detection and isolation (FDI) exist that do not require the specification of failure modes and are applicable to both actuators and sensors. These methods are known as the Failure Detection Filter and the method of Generalized Parity Relations. The latter method was applied to three different sensor types on the Mini-Mast. Failures were simulated in input-output data that were recorded during operation of the Mini-Mast. Both single and double sensor parity relations were tested and the effect of several design parameters on the performance of these relations is discussed. The detection of actuator failures is also treated. It is shown that in all the cases it is possible to identify the parity relations directly from input-output data. Frequency domain analysis is used to explain the behavior of the parity relations.

Vanschalkwyk, Christiaan Mauritz↗