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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Land cover change monitoring within the east central Louisiana study site: A case for large area surveys with LANDSAT multispectral scanner data

Results established for four digital procedures developed for characterizing the radiometric changes between multidate LANDSAT spectral data sets into meaningful measures of land cover/use dynamics are documented. Each technique's performance was contrasted against digitized land use change maps, which were produced from contemporaneous, retrospective aerophoto coverage, in a cell by cell comparison over a one half by one degree area in east central Louisiana as a standard for comparison. The four techniques identify from 10.5 to 13.0% loss in area of forestland in a five year period; however, they differ more by how accurately this amount of change is distributed, the need for ancillary ground truth, and amount of usable information that is extractable. All require some method of digitally co-registering the two data sets. All are capable of providing tabular statistics as well as map products. Two are capable of detecting changes and identifying their locations. The other two, in addition to this, provide information to qualify land cover conditions at each end of the study interval.

Burns, G. S.↗
NASA NTRS2007

Far-Ultraviolet Temperature Diagnostics for Hot Central Stars of Planetary Nebulae

The effective temperature of hot central stars of planetary nebulae is usually determined from the ratios of optical He II lines. However, far-ultraviolet spectra from the FUSE satellite of several hot (T(sub eff) > 70,000 K) hydrogen-rich central stars have stellar features that imply a significantly hotter effective temperature than that determined from He II. There are many stellar features in the long wavelength portion of the FUSE spectrum. These include O VI 1146-47, F VI 1039.5, FeVII 1118.6, 1141.4, FeVI 1120.9, 1131.5, and NiVI 1124.2, 1148.2. The strong FVI 1139.5 line is of interest because of the large overabundance (over 100X solar) of F in some PG1159 stars reported recently by Werner et al. (2005). Modeling these spectral features may provide an method for measuring the effective temperature of these stars independent of the He II lines. An example of HD 200516, the central star of NGC 7009 (T(sub eff)= 82000 K from He II vs 95000 K from Far-W metal lines) is presented.

Sonneborn, G.↗
NASA NTRS1999

Intercomparison of Various Algorithms in Determining Convective and Stratiform Precipitation

The paper presents the intercomparison of various algorithms in determining the convective and stratiform precipitation in tropical convection. The latent heat released from precipitation is the driving mechanism for the general circulation of the atmosphere and exhibits different vertical profile in convective and stratiform regimes of the tropical convection. The primary goal of this paper is to evaluate the performance of the operational convective/stratiform algorithm that is employed by the NASA Tropical Rainfall Measuring Mission (TRMM) ground validation program. The operational algorithm is based on the texture of radar reflectivity field at constant altitude. The TRMM ground validation program continuously monitors the tropical convection through ground based radar and rain gauge network at selected sites around the tropics and generates the rainfall products including the convective/stratiform rainfall map that can readily be used by the TRMM satellite program. An evaluation and improvement of these rainfall products requires additional measurements that can be available through field campaigns. The data used in this study was collected during the second phase of the Texas Florida Underflights (TEFLUN-B) field campaign in East Central Florida, a primary site of the TRMM ground validation program. The TEFLUN-B field campaign was conducted in August and September 1998 in support of the NASA Tropical Rainfall Measuring Mission (TRMM) satellite observations. An objective of the TEFLUN-B field campaign was to obtain the ground based precipitation measurements of Florida convection at different temporal and spatial scales. The field campaign had various components of precipitation measurements including dual wavelength precipitation profiler, various types of disdrometers and rain gauges, collocated about 40 km southwest of Melbourne NEXRAD radar. In this study, we examine the profiler based reflectivity and Doppler velocity and the disdrometer based drop size distribution observations to evaluate the operational scanning radar (i.e. NEXRAD) based convective/stratiform algorithm.

Tokay, Ali↗
NASA NTRS2002

Properties of the -513 km/s Ejecta in the Spectrum of Eta Carinae

In the spectral region 2400-3160A of Eta Carinae, we have identified approximately 500 absorption lines each with up to twenty velocity components. The -512 kilometers per second component is truely unique as 1) the typical line width is less than 3 kilometers per second, 2) the identified lines are in Fe I, Fe II, V II and Ti II, and 3) the lines originate from lower levels up to 2000 cm-1 above the ground level. We have measured the velocity centers, full width at half maximum and equivalent widths for approximately 100 absorption lines. Initial results were very confusing as we found more variation in central velocities than would be expected from known STIS echelle wavelength standards. Upon further review, we found that the reporteded wavelengths in the NIST and Kurucz databases were not sufficiently accurate. S. Johansson searched FTS laboratory measurements performed at Lund for V II and Ti II and provided much improved wavelength measures. Likewise, we find more variation in column density than expected statistically from the accuracy of the equivalent widths for lines originating from the same energy level. We are reviewing the published gf values and our measurements to improve the measured column densities. Some spectroscopy of the ejecta has already been accomplished at two different epochs. Preliminary measures of equivalent widths indicate there may be some variation with time, but we await measurements planned for July 2003 during the upcoming spectroscopic minimum of Eta Carinae. These observations were accomplished through STScI and funding was from STIS GTO resources.

Danks, Anthony↗
NASA NTRS2003

Properties of the -513 km/s Ejecta in the Spectrum of Eta Carinae

In the spectral region 2400-3160A of Eta Carinae, we have identified approximately 500 absorption lines each with up to twenty velocity components. The -512 kilometers per second component is truly unique as 1) the typical line width is less than 3 kilometers per second, 2) the identified lines are in Fe I, Fe II, VII and Ti II, and 3) the lines originate from lower levels up to 2000 cm-1 above the ground level. We have measured the velocity centers, full width at half maximum and equivalent widths for approximately 100 absorption lines. Initial results were very confusing as we found bore variation in central velocities than would be expected from known STIS echelle wavelength standards. Upon further review, we found that the reported wavelengths in the NIST and Kurucz databases were not sufficiently accurate. S. Johansson searched FTS laboratory measurements performed at Lund for V II and Ti II and provided much improved wavelength measures. Likewise, we find more variation in column density than expected statistically from the accuracy of the equivalent widths for lines originating from the same energy level. We are reviewing the published gf values and our measurements to improve the measured column densities. Some spectroscopy of the ejecta has already been accomplished at two different epochs. Preliminary measures of equivalent widths indicate there may be some variation with time, but we await measurements planned for July 2003 during the upcoming spectroscopic minimum of Eta Carinae. The observations were accomplished through STScI and funding was from STIS GTO resources.

Danks, A.↗
NASA NTRS2015

Lunar Health Monitor (LHM)

Orbital Research, Inc., has developed a low-profile, wearable sensor suite for monitoring astronaut health in both intravehicular and extravehicular activities. The Lunar Health Monitor measures respiration, body temperature, electrocardiogram (EKG) heart rate, and other cardiac functions. Orbital Research's dry recording electrode is central to the innovation and can be incorporated into garments, eliminating the need for conductive pastes, adhesives, or gels. The patented dry recording electrode has been approved by the U.S. Food and Drug Administration. The LHM is easily worn under flight gear or with civilian clothing, making the system completely versatile for applications where continuous physiological monitoring is needed. During Phase II, Orbital Research developed a second-generation LHM that allows sensor customization for specific monitoring applications and anatomical constraints. Evaluations included graded exercise tests, lunar mission task simulations, functional battery tests, and resting measures. The LHM represents the successful integration of sensors into a wearable platform to capture long-duration and ambulatory physiological markers.

Lisy, Frederick J.↗
DOE OSTI2022

Automated identification of local contamination in remote atmospheric composition time series

Abstract. Atmospheric observations in remote locations offer a possibility of exploring trace gas and particle concentrations in pristine environments. However, data from remote areas are often contaminated by pollution from local sources. Detecting this contamination is thus a central and frequently encountered issue. Consequently, many different methods exist today to identify local contamination in atmospheric composition measurement time series, but no single method has been widely accepted. In this study, we present a new method to identify primary pollution in remote atmospheric datasets, e.g., from ship campaigns or stations with a low background signal compared to the contaminated signal. The pollution detection algorithm (PDA) identifies and flags periods of polluted data in five steps. The first and most important step identifies polluted periods based on the derivative (time derivative) of a concentration over time. If this derivative exceeds a given threshold, data are flagged as polluted. Further pollution identification steps are a simple concentration threshold filter, a neighboring points filter (optional), a median, and a sparse data filter (optional). The PDA only relies on the target dataset itself and is independent of ancillary datasets such as meteorological variables. All parameters of each step are adjustable so that the PDA can be “tuned” to be more or less stringent (e.g., flag more or fewer data points as contaminated). The PDA was developed and tested with a particle number concentration dataset collected during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the central Arctic. Using strict settings, we identified 62 % of the data as influenced by local contamination. Using a second independent particle number concentration dataset also collected during MOSAiC, we evaluated the performance of the PDA against the same dataset cleaned by visual inspection. The two methods agreed in 94 % of the cases. Additionally, the PDA was successfully applied to a trace gas dataset (CO2), also collected during MOSAiC, and to another particle number concentration dataset, collected at the high-altitude background station Jungfraujoch, Switzerland. Thus, the PDA proves to be a useful and flexible tool to identify periods affected by local contamination in atmospheric composition datasets without the need for ancillary measurements. It is best applied to data representing primary pollution. The user-friendly and open-access code enables reproducible application to a wide suite of different datasets. It is available at https://doi.org/10.5281/zenodo.5761101 (Beck et al., 2021).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Anisotropic flow and flow fluctuations of identified hadrons in Pb–Pb collisions at $ \sqrt{s_{\textrm{NN}}}$ = 5.02 TeV

The first measurements of elliptic flow of π ± , K ± , p+$\bar{p}$, K$_{S}^{0}$, Λ+$\bar{Λ}$, $\phi$, Ξ – +$\barΞ$ + , and Ω – +$\barΩ$ + using multiparticle cumulants in Pb–Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV are resented. Results obtained with two- (v 2 {2}) and four-particle cumulants (v 2 {4}) are shown as a function of transverse momentum, p T , for various collision centrality intervals. Combining the data for both v 2 {2} and v 2 {4} also allows us to report the first measurements of the mean elliptic flow, elliptic flow fluctuations, and relative elliptic flow fluctuations for various hadron species. These observables probe the event-by-event eccentricity fluctuations in the initial state and the contributions from the dynamic evolution of the expanding quark–gluon plasma. The characteristic features observed in previous p T -differential anisotropic flow measurements for identified hadrons with two-particle correlations, namely the mass ordering at low p T and the approximate scaling with the number of constituent quarks at intermediate p T , are similarly present in the four-particle correlations and the combinations of v 2 {2} and v 2 {4}. In addition, a particle species dependence of flow fluctuations is observed that could indicate a significant contribution from final state hadronic interactions. The comparison between experimental measurements and CoLBT model calculations, which combine the various physics processes of hydrodynamics, quark coalescence, and jet fragmentation, illustrates their importance over a wide p T range.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1990

Investigation of turbulent transport in an axisymmetric sudden expansion

Simultaneous two-component laser velocimeter measurements were made in the incompressible turbulent flowfield following an axisymmetric sudden expansion. Mean velocities, Reynolds stresses, and triple products were measured and are presented at axial positions ranging from x/H = 0.2-14. A balance of the turbulent kinetic energy in the flow was performed. The production, convection, and diffusion of turbulent kinetic energy were computed directly from the experimental data using central differencing. A specially designed correction lens was employed to correct for optical aberrations introduced by the circular tube. This lens system allowed the accurate simultaneous measurement of axial and radial velocities in the test section. The experimental measurements were compared to predictions generated by a code that employed the k-epsilon turbulence model. Agreement was good for mean axial velocities, turbulent kinetic energy, and turbulent shear stresses. However, the modeled turbulent normal stresses where in poor agreement with the measured values. The modeled diffusion of turbulent kinetic energy was underpredicted in the region between the shear layer and the centerline of the flow giving lower values of turbulent kinetic energy downstream of the potential core than measured.

Gould, Richard D.↗
NASA NTRS1992

CCD photometry in the globular cluster NGC 288. I - Blue stragglers and main-sequence binary stars

Photometry based on a mosaic of CCD images in B and V is presented for the globular cluster NGC 288. The spatial coverage ranges from the cluster core to about 6 core radii, and stars have been measured over the absolute visual magnitude range -1.2 to 8.4. The cluster is shown to contain a significant number of blue straggler stars in the central regions, and there is an excess of objects brighter and redder than the single-star main-sequence in the color-magnitude plane. These objects are interpreted as a population of main-sequence binary stars. With this interpretation, the explicity measured fraction of binary stars is 10 percent, which sets a lower limit for the total binary population.

Bolte, Michael↗
NASA NTRS1999

The Special Sensor Microwave Imager Wind Dataset: A Source of Quantitative Information for the Ocean-to-Land Advection

It is well recognized that advection from the North Atlantic has a profound effect on the climatic conditions in central Europe. A new dataset of the ocean-surface winds, derived from the Special Sensor Microwave Imager, SSM/1, is now available. This satellite instrument measures the wind speed, but not the direction. However, variational analysis developed at the Data Assimilation Office, NASA Goddard Space Flight Center, by combining the SSM/I measurements with wind vectors measured from ships, etc., produced global maps of the ocean surface winds suitable for climate analysis. From this SSM/I dataset, a specific index I(sub na) of the North Atlantic surface winds has been developed, which pertinently quantifies the low-level advection into central Europe. For a selected time-period, the index I(sub na) reports the average of the amplitude of the wind, averaging only the speed when the direction is from the southwest (when the wind is from another direction, the contribution counts to the average as zero speed). Strong correlations were found between February I(sub na) and the surface air temperatures in Europe 50-60 deg N. In the present study, we present the correlations between I(sub na) and temperature I(sub s), and also the sensitivity of T(sub s), to an increase in I(sub na), in various seasons and various regions. We specifically analyze the flow of maritime-air from the North Atlantic that produced two extraordinary warm periods: February 1990, and early-winter 2000/2001. The very cold December 2001 was clearly due to a northerly flow. Our conclusion is that the SSM/I dataset is very useful for providing insight to the forcing of climatic fluctuations in Europe.

Otterman, J.↗
DOE OSTI2023

Measurement of the radius dependence of charged-particle jet suppression in Pb–Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV

The ALICE Collaboration reports a differential measurement of inclusive jet suppression using pp and Pb–Pb collision data at a center-of-mass energy per nucleon–nucleon collision $\sqrt{s_{NN}}=5.02$ TeV. Charged-particle jets are reconstructed using the anti-$k_T$ algorithm with resolution parameters R=0.2, 0.3, 0.4, 0.5, and 0.6 in pp collisions and R=0.2, 0.4, 0.6 in central (0–10%), semi-central (30–50%), and peripheral (60–80%) Pb–Pb collisions. A novel approach based on machine learning is employed to mitigate the influence of jet background. This enables measurements of inclusive jet suppression in new regions of phase space, including down to the lowest jet $p_T$ ≥ 40 GeV/c at R=0.6 in central Pb–Pb collisions. This is an important step for discriminating different models of jet quenching in the quark–gluon plasma. The transverse momentum spectra, nuclear modification factors, derived cross section, and nuclear modification factor ratios for different jet resolution parameters of charged-particle jets are presented and compared to model predictions. A mild dependence of the nuclear modification factor ratios on collision centrality and resolution parameter is observed. The results are compared to a variety of jet-quenching models with varying levels of agreement.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2026

Introduction to the Special Issue on Advanced Air Mobility Noise: Predictions, Measurements and Perception

This Special Issue focuses on noise associated with Advanced Air Mobility (AAM), an emerging class of predominantly electric distributed-propulsion aircraft designed for urban and regional transportation. As these vehicles move toward certification and deployment, noise has become a central challenge for regulatory approval and public acceptance, particularly due to operations in densely populated areas and at low altitudes. The 24 contributions in this issue address three key aspects of AAM noise: prediction, measurement, and human perception. Prediction studies span a wide range of modeling fidelities, from high-resolution simulations to improved semi-analytical approaches, and examine complex aeroacoustic mechanisms including rotor interactions, turbulence ingestion, and broadband noise generation. Measurement studies, largely at model scale, provide new insights into tonal and broadband noise characteristics across configurations and operating conditions, while supporting model validation. Perception-focused contributions investigate annoyance, sound quality metrics, and auralization, emphasizing the role of context and operational factors in shaping human response. Together, these works highlight the interdisciplinary nature of AAM noise research and the need for integrated approaches to enable quieter vehicle design.

Perception↗
DOE OSTI2024

Evidence of a toroidal magnetic field in the core of 3C 84

The spatial scales of relativistic radio jets, probed by relativistic magneto-hydrodynamic (RMHD) jet launching simulations and by most very long baseline interferometry (VLBI) observations differ by an order of magnitude. Bridging the gap between these RMHD simulations and VLBI observations requires selecting nearby active galactic nuclei (AGN), the parsec-scale region of which can be resolved. The radio source 3C 84 is a nearby bright AGN fulfilling the necessary requirements: it is launching a powerful, relativistic jet powered by a central supermassive black hole, while also being very bright. Using 22 GHz globe-spanning VLBI measurements of 3C 84 we studied its sub-parsec region in both total intensity and linear polarisation to explore the properties of this jet, with a linear resolution of ~0.1 parsec. We tested different simulation set-ups by altering the bulk Lorentz factor Γ of the jet, as well as the magnetic field configuration (toroidal, poloidal, helical). We confirm the persistence of a limb brightened structure, which reaches deep into the sub-parsec region. The corresponding electric vector position angles (EVPAs) follow the bulk jet flow inside but tend to be orthogonal to it near the edges. Our state-of-the-art RMHD simulations show that this geometry is consistent with a spine-sheath model, associated with a mildly relativistic flow and a toroidal magnetic field configuration.

3C 84 (NGC 1275)↗
DOE OSTI2026

Out-of-time-order correlators bridge classical transport and quantum dynamics

The out-of-time-order correlator (OTOC) has emerged as a central tool for quantifying decoherence across wide-ranging physical platforms. Here, we demonstrate its direct measurement in a classical ensemble using nuclear magnetic resonance with a modulated gradient spin echo sequence and extend the method into a multidimensional correlation to track exchange phenomena. Position is encoded through magnetic field gradients and momentum through the velocity autocorrelation function, enabling experimental access to OTOCs for proton motion confined within the self-similar lattice of the metal–organic framework MOF-808. Here, water confined to specified geometries within the MOF pores gives rise to spatially distinct diffusive eigenmodes with characteristic relative entropies. We demonstrate that periodic radio frequency driving combined with gradient modulation yields entropy evolution through the selection of distinct diffusion modes. Frequency-resolved diffusion spectra connect these entropy dynamics to classical heat exchange laws, revealing how operational features of quantum systems are mirrored in confined, macroscopic spin ensembles.

Fricke, Sophia N. [University of California, Berke↗
DOE OSTI2020

archi : pipeline for light curve extraction of CHEOPS background stars

ABSTRACT High precision time-series photometry from space is being used for a number of scientific cases. In this context, the recently launched CHaracterizing ExOPlanet Satellite (CHEOPS) (ESA) mission promises to bring 20 ppm precision over an exposure time of 6 h, when targeting nearby bright stars, having in mind the detailed characterization of exoplanetary systems through transit measurements. However, the official CHEOPS (ESA) mission pipeline only provides photometry for the main target (the central star in the field). In order to explore the potential of CHEOPS photometry for all stars in the field, in this paper, we present archi, an additional open-source pipeline module1 to analyse the background stars present in the image. As archi uses the official data reduction pipeline data as input, it is not meant to be used as an independent tool to process raw CHEOPS data but, instead, to be used as an add-on to the official pipeline. We test archi using CHEOPS simulated images, and show that photometry of background stars in CHEOPS images is only slightly degraded (by a factor of 2–3) with respect to the main target. This opens a potential for the use of CHEOPS to produce photometric time-series of several close-by targets at once, as well as to use different stars in the image to calibrate systematic errors. We also show one clear scientific application where the study of the companion light curve can be important for the understanding of the contamination on the main target.

Silva, André M.↗
DOE OSTI2023

The relationship between the incidence of X-ray selected AGN in nearby galaxies & star-formation rate

ABSTRACT We present the identification and analysis of an X-ray selected AGN sample that lie within the local (z < 0.35) galaxy population. From a parent sample of 22 079 MPA-JHU (based on SDSS DR8) galaxies, we identified 917 galaxies with central, excess X-ray emission (from 3XMM-DR7) likely originating from an AGN. We measured the host galaxies’ star formation rates and classified them as either star-forming or quiescent based on their position relative to main sequence of star formation. Only 72 per cent of the X-ray selected sample were identified as AGN using BPT selection; this technique is much less effective in quiescent hosts, only identifying 50 per cent of the X-ray AGN. We also calculated the growth rates of the black holes powering these AGN in terms of their specific accretion rate (∝ LX/M*) and found quiescent galaxies, on average, accrete at a lower rate than star-forming galaxies. Finally, we measured the sensitivity function of 3XMM so we could correct for observational bias and construct probability distributions as a function of accretion rate. AGN were found in galaxies across the full range of star formation rates ($\log _{10} \, \mathrm{SFR/M_\odot \ yr^{-1}} = -3\ \mathrm{to}\ 2$) in both star-forming and quiescent galaxies. The incidence of AGN was enhanced by a factor 2 (at a 3.5σ significance) in star-forming galaxies compared to quiescent galaxies of equivalent stellar mass and redshift, but we also found a significant population of AGN hosted by quiescent galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

The Double Chooz antineutrino detectors

This article describes the setup and performance of the near and far detectors in the Double Chooz experiment. The electron antineutrinos of the Chooz nuclear power plant were measured in two identically designed detectors with different average baselines of about 400 m and 1050 m from the two reactor cores. Over many years of data taking the neutrino signals were extracted from interactions in the detectors with the goal of measuring a fundamental parameter in the context of neutrino oscillation, the mixing angle $\theta _{13}$. The central part of the Double Chooz detectors was a main detector comprising four cylindrical volumes filled with organic liquids. From the inside towards the outside there were volumes containing gadolinium-loaded scintillator, gadolinium-free scintillator, a buffer oil and, optically separated, another liquid scintillator acting as veto system. Above this main detector an additional outer veto system using plastic scintillator strips was installed. The technologies developed in Double Chooz were inspiration for several other antineutrino detectors in the field. The detector design allowed implementation of efficient background rejection techniques including use of pulse shape information provided by the data acquisition system. The Double Chooz detectors featured remarkable stability, in particular for the detected photons, as well as high radiopurity of the detector components.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗