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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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DOE OSTI2025

Groundwater and surface water head from 2019 to 2022 at the Tims Branch in Savannah River Site (SRS), South Carolina.

This dataset contains groundwater and surface water head measurements for investigating hydro-biogeochemical processes in Tims Branch at the Savannah River Site, SC. Water levels were monitored using pressure transducers installed in surface water gauges and piezometers across three subsites in Tims Branch, identified as Wfloc, Snon (Snon1 and Snon2), and Sfloc. A barometric pressure logger was deployed in piezometers to correct pressure transducers from atmospheric pressure. Manual water level measurements were taken to calibrate transducer data. The dataset consists of at least paired groundwater and surface water head time series for each subsite, provided as individual CSV files. These data support analyses of surface-groundwater interactions, hydrologic controls on redox processes, and broader synthesis of wetland hydrology at the Savannah River Site.

ESS-DIVE CSV File Formatting Guidelines Reporting ↗

NASA NTRS1950

The application of the statistical theory of extreme values to gust-load problems

An analysis is presented which indicates that the statistical theory of extreme values is applicable to the problems of predicting the frequency of encountering the larger gust loads and gust velocities for both specific test conditions as well as commercial transport operations. The extreme-value theory provides an analytic form for the distributions of maximum values of gust load and velocity. Methods of fitting the distribution are given along with a method of estimating the reliability of the predictions. The theory of extreme values is applied to available load data from commercial transport operations. The results indicate that the estimates of the frequency of encountering the larger loads are more consistent with the data and more reliable than those obtained in previous analyses. (author)

Press, Harry↗

NASA NTRS1994

Global- to Micro-Scale Evolution of the Pinatubo Aerosol: Using Composite Data Sets to Build the Picture and Assess Consistency of Different Measurements

This paper brings together experimental. evidence required to build realistic models of the global evolution of physical, chemical, and optical properties of the aerosol resulting from the 1991 Pinatubo volcanic eruption. Such models are needed to compute the effects of the aerosol on atmospheric chemistry, dynamics, radiation, and temperature. Whereas there is now a large and growing body of post-Pinatubo measurements by a variety of techniques, some results are in conflict, and a self-consistent, unified picture is needed, along with an assessment of remaining uncertainties. This paper examines data from photometers, radiometers, impactors, optical counters/sizers, and lidars operated on the ground, aircraft, balloons, and spacecraft.

Russell, P. B.↗

NASA NTRS1979

Development and demonstration of manufacturing processes for fabricating graphite/PMR-15 polyimide structural elements

The processing requirements for graphite/PMR-15 polyimide composites developed to demonstrate the structural integrity of polyimide composite structural elements at temperatures up to 589K (600 F) are described. Major tasks included: quality assurance development; materials and process development; specification verification; flat panel fabrication; stiffened panel fabrication; honeycomb panel fabrication; chopped fiber moldings; and demonstration component fabrication. Materials, processing, and quality assurance documents were prepared from experimentally derived data. Structural elements consisting of flat panels, corrugated stiffeners, I-beams, hat stiffeners, honeycomb panels, and chopped fiber moldings were made and tested. Property data from 219K (-65 F) to 589K (600 F) were obtained. All elements were made in a production environment. The size of each element was sufficient to insure production capability and structural component applicability. Problems associated with adhesive bonding, laminate and structural element analysis, material variability, and test methods were addressed.

Sheppard, C. H.↗

NASA NTRS1980

Advanced oxygen-hydrocarbon rocket engine study

The advantages and disadvantages, system performance and operating limits, engine parametric data, and technology requirements for candidate high pressure LO2/Hydrocarbon engine systems are summarized. These summaries of parametric analysis and design provide a consistent engine system data base. Power balance data were generated for the eleven engine cycles. Engine cycle rating parameters were established and the desired condition and the effect of the parameter on the engine and/or vehicle are described.

Obrien, C. J.↗

NASA NTRS1988

Radiometric performance of AVIRIS: Assessment for an arid region geologic target

Data from several AVIRIS flight lines were examined to assess instrument stability and response. Both scene and in-flight calibration data were analyzed statistically. The data clearly indicates that, although the instrument output was noisy and unstable at the time of the data acquisition, valuable spectral signatures can still be extracted and analyzed. Some first order calibration corrections can be performed by forcing internal consistency within the data. AVIRIS data are delivered in band-interleaved-by-line format, but high efficiency routines were developed which access the data as either image or spectral planes and enable effective statistical and visual examination of both AVIRIS scenes and ancillary files. Two methods were used to extract spectral information from segment 4 of the Kelso Dunes flight. Both successfully identified at least three distinct spectral signatures, but neither has positively identified a specific material.

Kieffer, Hugh H.↗

DOE OSTI2023

Improving the Quality of Geothermal Data Through Data Standards and Pipelines Within the Geothermal Data Repository: Preprint

For machine learning outputs to be applicable to real world problems, high quality data are needed to ensure high quality results. With the more recent emphasis on machine learning in geothermal, there is an increasing need for greater focus on the quality of the data available for use in these projects. For example, Geothermal Operational Optimization Using Machine Learning (GOOML) utilized large quantities of geothermal power plant operational data to inform power plant operational configurations to maximize power generation. High quality datasets result from dependable sensors or devices collecting data, high frequency of measurements, sufficient data points, adequate metadata, reliable storage of data, and sufficient data curation. Another component that contributes to high quality data is reusability, which can be enhanced through data standardization. Data Standardization creates consistency in formatting and contents of like datasets, lessening preprocessing requirements and ensuring adequate information provided by a given dataset. The Geothermal Data Repository (GDR) aims to help improve data quality through automated data standardization for high-value datasets through the implementation of data pipelines alongside reliable and accessible long-term storage for datasets. As such, the GDR has decided to shift away from recommending the use of Excel-based content models and towards the implementation of automated data pipelines. This takes the burden of data standardization off the user and project team and will increase the availability of standardized geothermal data available through the GDR. A set of recommendations, or a data standard for each data type will exist with each data pipeline in order to advise data collection for maximum usability for future research. This paper serves to describe the GDR's proposed transition towards data standardization through automated data pipelines, to discuss the need for and value of such a shift, and to call for suggestions from the community regarding the most useful data standards and pipelines.

data↗

DOE OSTI2023

Energy transport analysis of NSTX plasmas with the TGLF turbulent and NEO neoclassical transport models

This work presents a study of plasma transport at low aspect ratio on the National Spherical Torus Experiment tokamak, where the turbulent and neoclassical energy fluxes calculated by the quasilinear Trapped Gyro Landau Fluid (TGLF) model and the multi species drift-kinetic Neoclassical solver (NEO) are validated against experimental data. The turbulent energy transport of two plasma discharges, one in the L-mode confinement regime and another in the H-mode regime, is dominated by electrostatic drift-wave instabilities, while the ion heat transport has a significant neoclassical contribution. The data analysis workflow is described in detail to understand how the variations of mapping and fitting of experimental data affect the power balance solution and subsequent flux-matching plasma profile predictions with the TGYRO solver. On average, the predicted plasma profiles are consistent with experimental data. However, the solutions are sensitive to various input parameters, including boundary conditions, and the electron-ion coupling. Linear gyrokinetic stability analysis demonstrates close agreement of the real frequencies of unstable modes between TGLF and CGYRO gyrokinetic simulations, but higher growth rates are predicted by TGLF, especially for the H-mode case. Estimates of the low-k modes' contributions to the total flux are consistent with linear stability analysis and the E × B suppression of turbulence in TGLF simulations with the SAT1 saturation model, while the SAT2 saturation model over-predicts the low-k modes' contribution in the H-mode case. Moreover, the results with SAT1 model are consistent with power balance analysis, which indicates only neoclassical ion energy fluxes inside ρ < 0.4 in the L-mode case and $\rho \unicode{x2A7D} 0.7$ in the H-mode case. The presence of multi-scale turbulence and ion-scale driven zonal flow mixing effects are also observed in TGLF scans of the electron turbulent heat flux over a range of temperature gradients and the electron-ion temperature ratio, which could explain the strong model sensitivity to variations of input parameters.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Measurements of dielectron production in Au + Au collisions at s N N = 27 , 39, and 62.4 GeV from the STAR experiment

We report systematic measurements of dielectron (e + e – ) invariant-mass M ee spectra at midrapidity in Au + Au collisions at s N N = 27 = 27, 39, and 62.4 GeV taken with the STAR detector at the Relativistic Heavy Ion Collider. For all energies studied, a significant excess yield of dielectrons is observed in the low-mass region ( 0.40 < M ee < 0.75 MeV / c 2 ) compared to hadronic cocktail simulations at freeze-out. Models that include an in-medium broadening of the ρ -meson spectral function consistently describe the observed excess. In addition, we report acceptance-corrected dielectron-excess spectra for Au + Au collisions at midrapidity ( |y ee | < 1) in the 0–80% centrality bin for each collision energy. The integrated excess yields for 0.4 < M ee < 0.75 GeV / c 2 , normalized by the charged particle multiplicity at midrapidity, are compared with previously published measurements for Au + Au at s N N = 27 = 19.6 and 200 GeV. Models that include an in-medium broadening of the ρ -meson spectral function consistently describe the observed excess. Furthermore, the normalized excess yields in the low-mass region show no significant collision energy dependence. The data, however, are consistent with model calculations that demonstrate a modest energy dependence.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1979

Effect of rotor meridional velocity ratio on response to inlet radial and circumferential distortion

Three single transonic fan stages, each having a different meridional velocity ratio across its rotor, were tested with two magnitudes of tip radial distortion and with a 90 deg circumferential distortion imposed on the inlet flow. The rotor with the lowest meridional velocity ratio (less than 0.9 at the tip) demonstrated the least degradation of performance due to these distortions. Loss and deviation angle data (as needed for performance prediction with radial distortion) calculated along actual streamlines for radially distorted flow and correlated against diffusion factor, showed consistent agreement with data calculated along design streamlines for undistorted flow.

Sanger, N. L.↗

NASA NTRS1984

A reevaluation of the 20-micron magnitude system

The 20-micron infrared magnitude system is reexamined by observing primary infrared standards and seven A V stars. The purpose is to determine whether Alpha Lyr has colors consistent with the average of A0 stars and to determine the relative magnitude of the primary standards to that of Alpha Lyr. The data presented are consistent with the interpretation that the spectrum of Alpha Lyr is a blackbody and that it is a viable flux standard at 10 and 20 microns. The absolute flux density scale, the physical quantity of interest, is found to be consistent with an extrapolation of the Alpha Lyr spectrum from the near infrared on the basis of the comparison of stars to Mars and asteroids. Adoption of a 0.0 magnitude for Alpha Lyr requires that the magnitudes given by Morrison and Simon (1973) and by Simon et al. (1972) be revised downward by 0.14 mag.

Tokunaga, A. T.↗

NASA NTRS1993

The occultation of 28 Sgr by Saturn - Saturn pole position and astrometry

Saturn's ring plane-defined pole position is presently derived from the geometry of Saturn's July 3, 1989 occultation of 28 Sgr, as indicated by the timings of 12 circular edges in the Saturn C-ring as well as the edges of the Encke gap and the outer edge of the Keeler gap. The edge timings are used to solve for the position angle and opening angle of the apparent ring ellipses; the internal consistency of the data set and the redundancy of stations indicates an absolute error of the order of 5 km. The pole position thus obtained is consistent with the pole and ring radius scale derived from Voyager occultation observations.

Hubbard, W. B.↗

NASA NTRS2008

ENSO/PDO-Like Variability of Tropical Ocean Surface Energy Fluxes Over the Satellite Era

Recent variations of tropical climate on interannual to near-decadal scales have provided a useful target for studying the nature of climate feedback processes. A strong warm / cold ENSO couplet (e.g. 1997-2000) along with several subsequent weaker events are prominent interannual signals that are part of an apparent longer term strengthening of the Walker circulation during the mid to late 1990's with some weakening thereafter. Decadal scale changes in tropical SST structure during the 1990s are accompanied by focusing of precipitation over the Indo-Pacific warm pool and an increase in tropical ocean evaporation of order 1.0 % /decade. Associated with ENSO and PDO-like tropical SST changes are surface freshwater and radiative fluxes which have important implications for heat and energy transport variations. In this study we examine how surface fluxes attending interannual to decadal SST fluctuations, e.g. precipitation (GPCP, TRMM), turbulent fluxes (OAFlux), and radiative fluxes (ERBE/CERES, SRB) are coupled. Using these data we analyze vertically-integrated divergence of moist static energy, divMSE, and its dry static energy and latent energy components. We examine consistency between these data sets and explore relationships between SST variations, flux changes and modulation of tropical Walker and Hadley circulations. Strong signatures ofMSE flux transport linking ascending and descending regions of tropical circulations are found. Relative strengths of these fluxes and transports are interpreted as a measure of efficiency in the overall process of tropical heat balance during episodes of warm or cold tropical SST.

Robertson, F. R.↗

NASA NTRS2016

Effect of Solar Array Plume Interactions on Hall Thruster Cathode Common Potentials

In typical implementations of spacecraft electric propulsion (EP) systems the electrical ground of the EP power processing units are resistively isolated from the main spacecraft electrical ground. Telemetry measuring the potential difference between EP power processing unit and the spacecraft electrical ground is usually referred to as the “cathode common” potential. In this paper we review flight and laboratory data on natural and EP generated plasma interactions with solar arrays, present the theory of spacecraft floating potentials, show how this theory is consistent with flight data, and extend this theory to spacecraft with high power Hall effect thrusters.

Katz, Ira↗

NASA NTRS2020

A Thousand Days After the Merger: Continued X-ray Emission from GW170817

Recent observations with the Chandra X-ray telescope continue to detect X-ray emission from the transient GW170817. In a total exposure of 96.6 ks, performed between 2020 March 9 and 16 (935–942 d after the merger), a total of 8 photons are measured at the source position, corresponding to a significance of ≈5σ. Radio monitoring with the Australian Telescope Compact Array (ATCA) shows instead that the source has faded below our detection threshold (<33 μJy, 3σ). By assuming a constant spectral index of β = 0.585, we derive an unabsorbed X-ray flux of ≈1.4 × 10−15 erg cm−2 s−1, higher than earlier predictions, yet still consistent with a simple structured jet model. We discuss possible scenarios that could account for prolonged emission in X-rays. The current data set appears consistent both with energy injection by a long-lived central engine and with the onset of a kilonova afterglow, arising from the interaction of the sub-relativistic merger ejecta with the surrounding medium. Long-term monitoring of this source will be essential to test these different models.

Gravitational waves↗

DOE OSTI2020

Using SPT polarization, Planck 2015, and non-CMB data to constrain tilted spatially-flat and untilted nonflat ΛCDM, XCDM, and ΦCDM dark energy inflation cosmologies

We use six tilted spatially-flat and untilted non-flat dark energy cosmological models in analyses of South Pole Telescope polarization (SPTpol) cosmic microwave background (CMB) data, alone and in combination with Planck 2015 CMB data and non-CMB data, namely, the Pantheon Type Ia supernovae apparent magnitudes, a collection of baryon acoustic oscillation data points, Hubble parameter measurements, and growth rates. Although the cosmological models that best-fit the Planck CMB and non-CMB data do not provide good fits to the SPTpol data, with the χ2's exceeding the expected value, given the uncertainties, in each model the cosmological parameter constraints from the SPTpol data and from the Planck CMB and non-CMB data are largely mutually consistent. Furthermore, when the smaller angular scale SPTpol data are used jointly with either the Planck data alone or with the Planck CMB and the non-CMB data to constrain untilted non-flat models, spatially-closed models remain favored over their corresponding flat limits. When used in conjunction with Planck data, non-CMB data (baryon acoustic oscillation measurements in particular, from six experiments) have significantly more constraining power than the SPTpol data.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1979

Analysis and test for space shuttle propellant dynamics (1/10th scale model test results). Volume 2: 1/10th scale model test data

Thirty sets of test data selected from the 89 low-g aircraft tests flown by NASA KC-135 zero-g aircraft are listed in tables with their accompanying test conditions. The data for each test consists of the time history plots of digitalized data (in engineering units) and the time history plots of the load cell data transformed to the tank axis system. The transformed load cell data was developed for future analytical comparisons; therefore, these data were transformed and plotted from the time at which the aircraft Z axis acceleration passed through l-g. There are 14 time history plots per test condition. The contents of each plot is shown in a table.

Berry, R. L.↗

NASA NTRS1983

Minimum information modelling of structural systems with uncertain parameters

Work is reviewed wherein the design of active structural control is formulated as the mean-square optimal control of a linear mechanical system with stochastic parameters. In practice, a complete probabilistic description of model parameters can never be provided by empirical determinations, and a suitable design approach must accept very limited a priori data on parameter statistics. In consequence, the mean-square optimization problem is formulated using a complete probability assignment which is made to be consistent with available data but maximally unconstrained otherwise through use of a maximum entropy principle. The ramifications of this approach for both robustness and large dimensionality are illustrated by consideration of the full-state feedback regulation problem.

Hyland, D. C.↗

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