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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Temperature and pressure determinations in the Venus atmosphere by means of high-resolution spectra from 1 to 2.5 microns

Twenty-one bands of CO2 and the 2-0 band of CO were analyzed for best temperature and pressure fits from Venus spectra obtained with the 'Connes' interferometer at the Steward Observatory 2.25-m telescope during the spring of 1971. An average temperature of 241 plus or minus 7 K, an effective pressure of 0.12 plus or minus 0.06 atm, and an average two-way transmission abundance of 3 km-amagat were determined. No difference in temperature or pressure between hot bands, a double hot band, and regular bands was found. The results indicate that, most likely, spectroscopic line formation occurs in a relatively clear space above a scattering cloud layer with a reasonably well-defined upper boundary.

Dierenfeldt, K. E.↗
NASA NTRS2006

A Lagrangian trajectory view on transport and mixing processes between the eye, eyewall, and environment using a high resolution simulation of Hurricane Bonnie (1998)

The transport and mixing characteristics of a large sample of air parcels within a mature and vertically sheared hurricane vortex is examined. Data from a high-resolution (2 km grid spacing) numerical simulation of "real-case" Hurricane Bonnie (1998) is used to calculate Lagrangian trajectories of air parcels in various subdomains of the hurricane (namely, the eye, eyewall, and near-environment) to study the degree of interaction (transport and mixing) between these subdomains. It is found that 1) there is transport and mixing from the low-level eye to the eyewall that carries high- Be air which can enhance the efficiency of the hurricane heat engine; 2) a portion of the low-level inflow of the hurricane bypasses the eyewall to enter the eye, that both replaces the mass of the low-level eye and lingers for a sufficient time (order 1 hour) to acquire enhanced entropy characteristics through interaction with the ocean beneath the eye; 3) air in the mid- to upper-level eye is exchanged with the eyewall such that more than half the air of the eye is exchanged in five hours in this case of a sheared hurricane; and 4) that one-fifth of the mass in the eyewall at a height of 5 km has an origin in the mid- to upper-level environment where thet(sub e) is much less than in the eyewall, which ventilates the ensemble average eyewall theta(sub e) by about 1 K. Implications of these findings to the problem of hurricane intensity forecasting are discussed.

Cram, Thomas A.↗
NASA NTRS1986

Performance studies on the application of four-engine and two-engine USB propulsive lift to the E-2C aircraft

A study has been completed of the performance benefits to be derived from applying advanced upper-surface blowing (USB) propulsive-lift technology to the E-2C aircraft. The results of comparing four-engine with two-engine USB configurations are discussed, and engine sizing and aerodynamic/structural considerations pertaining to the E-2C/USB modification are examined. The effects of the modification on performance are described in detail with regard to takeoff distance and landing distance estimation in free-deck operations, operations using catapult and arresting gear, ceiling and radar surveillance missions, and range and endurance capability.

Riddle, D. W.↗
DOE OSTI2024

Search for e + e − → η ′ ψ ( 2 S ) at center-of-mass energies from 4.66 to 4.95 GeV

Using data samples with an integrated luminosity of 4.67 fb − 1 collected by the BESIII detector operating at the BEPCII Collider, we search for the process e + e − → η ′ ψ ( 2 S ) at center-of-mass energies from 4.66 to 4.95 GeV. No significant signal is observed, and upper limits for the Born cross sections σ B ( e + e − → η ′ ψ ( 2 S ) ) at the 90% confidence level are determined. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
NASA NTRS2000

The Use of Water Vapor for Detecting Environments that Lead to Convectively Produced Heavy Precipitation and Flash Floods

This Tech Report summarizes years of study and experiences on using GOES Water vapor (6.7 micron and precipitable water) and Special Sensor Microwave Imager (SSM/1) from the Defense Meteorological Satellite Program (DMSP) derived Precipitable Water (PNAI) for detecting environments favorable for convectively produced flash floods. An emphasis is on the moisture. upper air flow, and equivalent potential temperature (Theta(sub e)) patterns that lead to devastating flood events. The 15 minute 6.7 micron water vapor imagery is essential for tracking middle to upper tropospheric disturbances that produce upward vertical motion and initiate flash flood producing systems. Water vapor imagery at 6.7 micron is also used to detect surges of upper level moisture (called tropical water vapor plumes) that have been associated with extremely heavy rainfall. Since the water vapor readily depicts lifting mechanisms and upper level moisture, water vapor imagery is often an excellent source of data for recognizing patterns of heavy precipitation and flash floods. In order to analyze the depth of the moisture, the PW aspects of the troposphere must be measured. The collocation (or nearby location) of high values ofP\V and instability are antecedent conditions prior to the flash flood or heavy rainfall events. Knowledge of PW magnitudes have been used as thresholds for impending flash flood events, PW trends are essential in flash flood prediction. Conceptual models and water vapor products are used to study some of the characteristics of convective systems that occurred over the United States of America (USA) during the summer of 1997 and the 1997-1998 El Nino. P\V plumes were associated with most of the \vest coast heavy precipitation events examined during the winter season of 1997 - 1998, In another study, conducted during the summer season of 1997. results showed that the collocation of water vapor (6.7 micron) and P\N' plumes possessed higher correlations with predicted rainfall amounts than when PW plumes occurred by themselves (i.e.. without the presence of 6.7 micron water vapor plumes). Satellite Analysis Branch (SAB) meteorologists use the 6.7 micron water and P\V products for their QPE's (interactive Flash Flood Analyzer (IFFA) and Auto-Estimator precipitation estimates), Outlooks, and heavy precipitation briefings with the Hydrometeorological Prediction Center/National Center for Environmental Prediction.

Scofield, Rod↗
DOE OSTI2025

Search for lepton-flavor-violating tau decays to ℓα at Belle

We report a search for the lepton-flavor-violating decays τ ± → ℓ ± α (ℓ = e, μ), where α is an undetected spin-0 particle, such as an axion-like particle using 736 × 10 6 tau lepton pairs collected by the Belle detector at the KEKB asymmetric-energy e + e − collider. We find no evidence of signal and obtain the most stringent upper limits on the branching fractions at 95% confidence level: $\mathcal{B}$ (τ ± → e ± α) < (0.4–6.4) × 10 −4 and $\mathcal{B}$ (τ ± → μ ± α) < (0.2–3.5) × 10 −4 at 95% confidence level for an α mass in the range 0.0 ≤ m α ≤ 1.6 GeV/c 2 .

tau physics↗
NASA NTRSDate not supplied

Mars 2020's First Sample: The Fractured Rough Rock Unit on the Floor of Jezero Crater

A central goal of the Mars 2020 mission is to select and cache samples for future return to Earth. The first samples targeted for collection are from the crater-retaining, Crater Floor Fractured Rough (CF-Fr) unit of Stack et al., 2020.The CF-Fr unit is a topographically low unit in the current Jezero setting, likely overlain by morphologically discrete units, including possible Jezero delta deposits and eolian features. CF-Fr is an aerially extensive unit with lobate margins. Two distinct morphologies are observed: a locally-exposed lower expression, with flat relatively horizontal light-toned surfaces and polygonal fracturing, and an upper expression consisting of up to ~5vertical meters of massive, sometimes boulder-producing, material. The locally-exposed lower expression appears to represent a local ground level in which the upper material has been removed. Near the Octavia E. Butler landing site, the lower morphology is exposed as polygonally-fractured, light-toned bedrock that appears to grade continuously into higher-standing massive outcrops, often with no clearly exposed contact. Further south, a darker upper expression of the CF-Fr unit is more distinct and the unit exhibits some horizontal layering. The Perseverance rover will initially sample the flat-lying expression of this unit. Hypotheses for the origin of CF-Fr include fluvial, aeolian, or lacustrine sediment likely derived from the Jezero watershed, and/or pyroclastic material resulting from regional volcanism. Geochronology of the returned sample could be used to help constrain the timing of geological events in Jezero. It may also help constrain stratigraphic relationships with crater-retaining units outside of Jezero within the Nili Planum, which could be used to calibrate the cratering chronology of Mars. Paleomagnetic analyses of an oriented sample could establish the history of the martian dynamo and whether it persisted into the Hesperian. Finally, if present, secondary phases within the primary deposit would help constrain diagenetic conditions and inform post-depositional aqueous and potentially habitable environmental conditions.

Justin I Simon↗
NASA NTRS1984

Small-scale variations in the galactic magnetic field - The rotation measure structure function and birefringence in interstellar scintillations

The structure function of rotation measures of extragalactic sources and birefringence in interstellar scintillations are used to investigate variations in the interstellar magnetic field on length scales of about 0.01-100 pc and 10 to the 11th cm, respectively. Model structure functions are derived for the case of a power-law power spectrum of irregularities in the quantity (n(e)B), and an estimate for the structure function is computed for several regions of the sky using data on extragalactic sources. The results indicate an outer angular scale for rotation measure (RM) variations of not less than about 5 deg (a linear scale of about 9-90 pc at a distance of 0.1-1 kpc). There is also evidence for RM variations on angular scales as small as 1 arcmin, but it cannot be determined whether these are intrinsic to the source or caused by the interstellar medium. The effect of a random, Faraday-active medium on the diffraction of radio waves is derived, and an upper limit to the variations in n(e)B on a length scale of 10 to the 11th cm is obtained from available observations.

Simonetti, J. H.↗
NASA NTRS1981

High-resolution profiles for the diffuse interstellar band at 6196 A

The 6196.0 A diffuse feature is observed in various directions towards moderately and slightly reddened stars at high spectral resolution and signal to noise ratio. The feature is found to be symmetric with no fine structure with an equivalent-width upper unit paralleling that of H2. The feature is as narrow as 0.4 A, although much broader in other stars due to cloud blending in the line of sight, and is absent in all observed stars with E(B-V) less than 0.1, and upper limits more than an order of magnitude below values extrapolated from more reddened stars. Upper limits are determined by multiplying the square root of the number of channels in which the line may lie, and another narrow feature, although highly asymmetric, is observed at 6194.6 A. It is concluded that the results increase the possibility of at least one of the diffuse band carriers being a molecule.

Smith, W. H.↗
NASA NTRS1979

The behavior of tropical ozone during the stratospheric warming of March-April 1976

The backscatter ultraviolet spectrometer on the Atmosphere Explorer-E satellite obtained ozone data for the upper stratosphere and lower mesosphere from an equatorial orbit near the time of the March-April 1976 stratospheric warming. A simple inversion technique allows the extraction of information on the absolute ozone abundance and its longitudinal variation from the measured radiances. Between altitudes of 35 and 60 km tropical O3 in constant pressure layers exhibits increased spatial variations on length scales of 20 to 30 deg in longitude after the onset of the polar warming, indicating enhanced wave activity. One week after the polar vortex breakdown, upper stratospheric O3 begins a relaxation toward the unperturbed state, while that in the lower mesosphere continues to show maximum variations near + or 10% of the longitudinally averaged value. Although the degree of horizontal structure increases during the warming, the absolute O3 amounts averaged over longitude between 35 and 60 km in altitude remain nearly constant in time. The observed behavior is consistent with that expected from enhanced vertical transport of O3 in the tropics with accompanying adiabatic temperature changes which alter the chemical loss rate.

Frederick, J. E.↗
DOE OSTI2024

Search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ

We present the first search for the leptonic decays D * + → e + ν e and D * + → μ + ν μ by analyzing a data sample of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, corresponding to an integrated luminosity of 6.32 fb − 1 . No significant signal is observed. The upper limits on the branching fractions for D * + → e + ν e and D * + → μ + ν μ are set to be 1.1 × 10 − 5 and 4.3 × 10 − 6 at 90% confidence level, respectively. Published by the American Physical Society 2024

Astronomy & Astrophysics↗