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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Strategies for using membrane-based separations to extract critical metals from waste streams

Critical metals are currently extracted by mining followed by their purification. These processes are costly and not environmentally very desirable. In this perspective paper we discuss the potential of extracting these critical metals from a range waste-streams available in abundance globally. These waste streams include brine from desalination plants, effluents from oil drilling and hydraulic fracturing, as well as discharges from various industrial processes such as metal finishing, electroplating, mining, and chemical manufacturing. We show that with a range of new separation processes being developed their separation is showing potential of being both technologically and economically feasible. We also show how high performance computing can be combined with computational models to screen and accelerate the development of new technologies for extracting critical metals from waste streams.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Anomaly Detection and Approximate Similarity Searches of Transients in Real-time Data Streams

Abstract We present Lightcurve Anomaly Identification and Similarity Search ( LAISS ), an automated pipeline to detect anomalous astrophysical transients in real-time data streams. We deploy our anomaly detection model on the nightly Zwicky Transient Facility (ZTF) Alert Stream via the ANTARES broker, identifying a manageable ∼1–5 candidates per night for expert vetting and coordinating follow-up observations. Our method leverages statistical light-curve and contextual host galaxy features within a random forest classifier, tagging transients of rare classes ( spectroscopic anomalies), of uncommon host galaxy environments ( contextual anomalies), and of peculiar or interaction-powered phenomena ( behavioral anomalies). Moreover, we demonstrate the power of a low-latency (∼ms) approximate similarity search method to find transient analogs with similar light-curve evolution and host galaxy environments. We use analogs for data-driven discovery, characterization, (re)classification, and imputation in retrospective and real-time searches. To date, we have identified ∼50 previously known and previously missed rare transients from real-time and retrospective searches, including but not limited to superluminous supernovae (SLSNe), tidal disruption events, SNe IIn, SNe IIb, SNe I-CSM, SNe Ia-91bg-like, SNe Ib, SNe Ic, SNe Ic-BL, and M31 novae. Lastly, we report the discovery of 325 total transients, all observed between 2018 and 2021 and absent from public catalogs (∼1% of all ZTF Astronomical Transient reports to the Transient Name Server through 2021). These methods enable a systematic approach to finding the “needle in the haystack” in large-volume data streams. Because of its integration with the ANTARES broker, LAISS is built to detect exciting transients in Rubin data.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

The effect of injection angle on the interaction between sonic secondary jets and a supersonic free stream

An experimental investigation, as part of a research program on the development of technology for the design of supersonic combustion ramjets, has been conducted to determine the effect of injection angle on the jet penetration, mixing rate, and airstream total-pressure recovery downstream of five laterally spaced sonic hydrogen jets flush mounted on a flat plate. Results of this investigation indicated that at lower injection angles less free-stream momentum loss was required to turn and accelerate the injected gas downstream and, thereby, less flow disturbance and total-pressure loss were produced. In addition, lower injection angles resulted in improved fuel distribution and faster mixing of the injected gas with the free stream. A correlating parameter, developed from considerations of the effective-momentum-flux differences between the injected gas and the free-stream air, predicted greater penetration and faster mixing for the lower injection angles.

Mcclinton, C. R.↗
NASA NTRS1972

Flow field measurements for space-shuttle-related cylindrical configurations in hypersonic streams.

Use of surface pressures, heat-transfer rates, and flow-visualization photographs to define the flowfields for simulated infinite cylinders. Four cylindrical cross sections were studied in the experimental program, which was conducted at free-stream Mach numbers of 5 to 15, free-stream unit Reynolds numbers from 2 to 20 million per foot, and angles of attack from 30 to 90 deg. Although swept-cylinder theory provides a reasonable correlation of the measured laminar heat-transfer rates in the plane of symmetry, improved correlation with the measurements is obtained if the three-dimensional nature of the flow is taken into account. In cases where the boundary layer on the windward forebody was turbulent, the large velocity gradients near the chines produced relaminarization of the boundary layer prior to separation. The average heat-transfer-rate in the separated region, which is weakly dependent on the free-stream conditions, was found to be a linear function of the angle of attack. For a given flow condition the effect of the leeward geometry on heat transfer can be correlated by a single geometric parameter which is dependent on the location of separation.

Bertin, J. J.↗
NASA NTRS1972

Applications of remote sensing to stream discharge predictions

A feasibility study has been initiated on the use of remote earth observations for augmenting stream discharge prediction for the design and/or operation of major reservoir systems, pumping systems and irrigation systems. The near-term objectives are the interpolation of sparsely instrumented precipitation surveillance networks and the direct measurement of water loss by evaporation. The first steps of the study covered a survey of existing reservoir systems, stream discharge prediction methods, gage networks and the development of a self-adaptive variation of the Kentucky Watershed model, SNOPSET, that includes snowmelt. As a result of these studies, a special three channel scanner is being built for a small aircraft, which should provide snow, temperature and water vapor maps for the spatial and temporal interpolation of stream gages.

Krause, F. R.↗
NASA NTRS1973

Stabilization of electron streams in type 3 solar radio bursts

It is shown that the electron streams that give rise to Type 3 solar radio bursts are stable and will not be decelerated while propagating out of the solar corona. The stabilization mechanism depends on the parametric oscillating two stream instability. Radiation is produced near the fundamental and second harmonic of the local electron plasma frequency. Estimates of the emission at the second harmonic indicate that the wave spectra created by the oscillating two stream instability can account for the observed intensities of Type 3 bursts.

Papadopoulos, K.↗
NASA NTRS1973

Interpretation of land use and stream order, Pawnee River Basin, Kansas

The author has identified the following significant results. Land use and stream orders were mapped from ERTS-1 imagery covering the Pawnee River Basin. Total area of the basin, irrigated dry land crop area, and rangeland area were determined. The stream order of the basin was calculated by the Strahler method and provided more detail than is available on the comparable 1:250,000 sheets. This study has demonstrated the feasibility of using ERTS-1 imagery to map stream networks in greater detail than is required for 1:250,000 scale. The utility of ERTS-1 has also been demonstrated for mapping and mensuration of data relating to performance of ground cover types and the extent of irrigation.

Morain, S. A.↗
NASA NTRS1972

Numerical solution of laminar jet mixing with and without free stream.

Systematic numerical solutions of two-dimensional and axisymmetrical laminar jet of an incompressible fluid with and without free stream have been obtained. For the case without free stream, the exact numerical solutions have been obtained for different initial velocity profiles and compared with experimental results and similarity solutions. For the case with free stream, the numerical solutions have been compared with the linearized analytical solutions. An approximate numerical solution for the axial velocity distribution of the three-dimensional laminar jet is proposed. The accuracy of the method has been determined from the exact solutions of the two limiting cases of three-dimensional jets, i.e., the two-dimensional and axisymmetric cases.

Pai, S. I.↗
NASA NTRS1974

The minimum free-stream wind speed for initiating motion of surface material on Mars

Estimates of the minimum free-stream wind speed that is required for initiating the motion of surficial material on Mars have ranged from 30 to about 200 meters per second. Thus the best value for this quantity is not well established. Graphical comparison of much of the pertinent data taken in the laboratory and in the field on Earth provides a minimum value for the Bagnold coefficient of 0.08 and this in turn provides a minimum value for the threshold friction velocity of 1.3 meters per second for initiating motion of particulate matter on Mars at low elevations where the pressure is 7 millibars. The most appropriate value of the ratio of friction velocity to free-stream velocity for putative unstable condition appears to be 0.026. Thus the minimum free-stream wind speed for initiating motion is obtained as 50 meters per second. If the surface material on Mars, however, is less cohesive than that on earth, the minimum value may be smaller.

Wood, G. P.↗
NASA NTRS1974

Gulf Stream model

Surface elevation deviations in the Gulf Stream region off the eastern coast of the United States between Wallops Island, Virginia and Miami, Florida were investigated. The main causes of surface elevation deviations are geoid perturbations due to the continental shelf and the geostrophic adjustment of the density field due to the Gulf Stream. Quantitative surface elevation profiles were calculated based on geophysical measurements of gravity anomalies and hydrographic data. The results are presented graphically along with contemporaneous weather data. Comparisons are made between the profiles based on hydrographic data and a mean theoretical model. The theory of geostrophic flows including some classical Gulf Stream models is also presented briefly.

Source record↗
NASA NTRS1974

Stabilization of electron streams in type III solar radio bursts

We show that the electron streams that give rise to type III solar radio bursts are stable and will not be decelerated while propagating out of the solar corona. The stabilization mechanism depends on the parametric oscillating two-stream instability. Radiation is produced near the fundamental and second harmonic of the local electron plasma frequency. Estimates of the emission at the second harmonic indicate that the wave spectra created by the oscillating two-stream instability can account for the observed intensities of type III bursts.

Papadopoulos, K.↗
NASA NTRS1975

Southern Hemisphere meteor stream determinations

Meteor orbits have been deduced from radio observations of meteor trails carried out at Adelaide, Australia, using a combined multistation CW and pulse radar system operating at 27 MHz. The orbits of 1667 meteors have been determined down to a limiting radio magnitude of +8. The data have been systematically searched for stream meteors, and the significance of minor associations has been appraised. Altogether, 40.4% of the orbits were found to be associated with at least one other orbit, and 29.8% with two or more. Numerous minor streams with high inclination and low eccentricity have been found at deep southern declinations from December to March, with little activity in this quarter during June and October. In addition to confirming several previously established cometary associations, a comprehensive search has indicated that 34 of the meteor associations may be related to 17 comets. Associations between several long-period comets and low-eccentricity high-inclination streams appear to be indisputable, and they confirm the origin of at least some of the 'toroidal group' meteors.

Gartrell, G.↗
NASA NTRS1975

Application of the theory of jet stream to the asteroidal belt

The possibility of incorporating the resonant effect and jet stream formation process into the problems of the Hilda asteroids and Kirkwood gaps is discussed qualitatively. It appears that formation of the precursor jet streams of the resonant asteroids in the main belt would be suppressed due to the collisional perturbation effect of the ambient matter in this region. Together with the biased distribution of near-resonant asteroids, the depletion across the Kirkwood gaps could be understood. Within the context of jet stream theory the existence of Hilda asteroids outside the main belt requires the original limit of the main belt to be not much more extensive than the present value of 3.5 AU. This is suggestive of a cosmogonic origin of the observed outer limit.

Ip, W.-H.↗
NASA NTRS1976

Interplanetary stream magnetism - Kinematic effects

The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

Burlaga, L. F.↗
NASA NTRS1976

Three-dimensional interplanetary stream magnetism and energetic particle motion

Cosmic rays interact with mesoscale configurations of the interplanetary magnetic field. A technique is presented for calculating such configurations in the inner solar system, which are due to streams and source conditions near the sun, and maps of magnetic field are constructed for some plausible stream and source conditions. One effect of these mesoscale configurations on galactic cosmic rays is shown to be an out-of-the-ecliptic gradient drift sufficient to explain Forbush decreases. The effects on solar energetic particles include small polar drifts due to the field gradients and a possibly large modification of the time-intensity profiles and anisotropy characteristics due to the formation of mirror configurations in space. If a diffusion model is applicable to solar particles, the true diffusion coefficient will be masked by the effects of streams. A conceptual model which incorporates these ideas and those of several other models is presented.

Barouch, E.↗
NASA NTRS1976

Gas dynamics of semidetached binaries. II - The vertical structure of the stream

The letter considers the three-dimensional dynamics of the stream in semidetached binaries undergoing Roche-lobe overflow. Results of an earlier communication are generalized to include the dynamic effects in the direction perpendicular to the orbital plane. It is found that the scale height of the stream characteristically exceeds its corresponding hydrostatic value by a significant factor because the inertia of the gas prevents it from responding instantaneously to the changing gravitational field. This effect is important for the interpretation of observations relating to stream-disk impacts in cataclysmic variables and in binary X-ray sources of low total mass.

Lubow, S. H.↗
NASA NTRS1976

Effects of stream-associated fluctuations upon the radial variation of average solar-wind parameters

The effects of nonlinear fluctuations due to solar wind streams upon radial gradients of average solar wind parameters are computed, using a numerical MHD model for both spherically symmetric time dependent and corotating equatorial flow approximations. Significant effects of correlations are found between fluctuations upon the gradients of azimuthal magnetic fields, radial velocity, density and azimuthal velocity. Between 400 to 900 solar radii stream interactions have transferred the major portion of the angular momentum flux to the magnetic field; at even greater distances the plasma again carries the bulk of the angular momentum flux. The average azimuthal component of the magnetic field may decrease as much as 10% faster than the Archimedean spiral out to 6 AU due to stream interactions, but this result is dependent upon inner boundary conditions.

Goldstein, B. E.↗
NASA NTRS1976

Variable stream control engine concept for advanced supersonic aircraft: Features and benefits

The Variable Stream Control Engine is studied for advanced supersonic cruise aircraft. Significant environmental and performance improvements relative to first generation supersonic turbojet engines are cited. Two separate flow streams, each with independent burner and nozzle systems are incorporated within the engine. By unique control of the exhaust temperatures and velocities in two coannular streams, significant reduction in jet noise is obtained.

Howlett, R. A.↗