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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Topological controls on aluminosilicate glass dissolution: Complexities induced in hyperalkaline aqueous environments

Abstract Fly ash, an aluminosilicate composite consisting of disordered (major) and crystalline (minor) compounds, is a low‐carbon alternative that can partially replace ordinary portland cement (OPC) in the binder fraction of concrete. Therefore, understanding the reactivity of fly ash in the hyperalkaline conditions prevalent in concrete is critical to predicting concrete's performance; including setting and strength gain. Herein, temporal measurements of the solution composition (using inductively coupled plasma‐optical emission spectrometry: ICP‐OES) are used to assess the aqueous dissolution rate of monophasic synthetic aluminosilicate glasses analogous to those present in technical fly ashes, under hyperalkaline conditions (10 ≤ pH ≤ 13) across a range of temperatures (25°C ≤ T≤45°C). The dissolution rate is shown to depend on the average number of topological constraints per atom within the glass network (n c , unitless), but this dependence weakens with increasing pH (>10). This is postulated to be on account of: (a) time‐dependent changes in the glass’ surface structure, that is, the number of topological constraints; and/or (b) a change in the dissolution mechanism (eg from network hydrolysis to transport control). The results indicate that the topological description of glass dissolution is most rigorously valid only at very short reaction times (ie at high undersaturations), especially under conditions of hyperalkalinity. These findings provide an improved basis to understand the underlying factors that affect the initial and ongoing reactivity of aluminosilicate glasses such as fly ash in changing chemical environments, for example, when such materials are utilized in cementitious composites.

Oey, Tandré↗
DOE OSTI2025

Characterizing the Impact of GPU Power Management on an Exascale System

As GPU-accelerated high-performance computing (HPC) systems approach exascale performance, controlling energy consumption without compromising throughput is essential. Architectures such as the AMD MI250X-based Frontier supercomputer provide runtime mechanisms like frequency and power capping, enabling energy tuning without modifying application code. Although both target energy reduction, they operate via distinct hardware control paths and influence workloads differently. We present a comprehensive evaluation of these strategies on a leadership-class system using diverse HPC proxy applications representative of production workloads. Our study analyzes performance–energy trade-offs across multiple capping levels, node counts (1 and 32), and application profiles. Results show that frequency capping generally achieves higher energy efficiency and scalability, with gains of up to 13.2% without performance loss, while power capping is more effective for single-node runs or bursty GPU utilization. We also provide practical guidelines to help system administrators and users balance energy efficiency and performance in large-scale scientific workloads.

Costa, Mariana [Universidade Federal do Rio Grande↗
DOE OSTI2024

Comparing Pr 3+ and Nd 3+ for deactivating the Er 3+ : 4 I 13/2 level in lanthanum titanate glass

Erbium lanthanum titanate glasses were prepared by levitation melting for the spectroscopic study of ways to promote the mid-infrared fluorescence. Two series of heavily erbium doped glasses (15 wt%) were prepared with the addition of either Pr 3+ or Nd 3+ in amounts relative to Er 3+ of 0.05, 0.1, and 0.2. Both ions quench the lower Er 3+ laser level with the Pr 3+ doing so more rapidly. Although high co-dopant concentrations result in higher energy transfer, as clearly evidenced in upconversion and downconversion fluorescence measurements, the mid-infrared lifetime also suffers a reduction and, therefore, a balance must be struck in the co-dopant concentration. Lifetime and spectral measurements indicate that, at a fixed relative co-dopant amount, Pr 3+ is more effective than Nd 3+ at removing the bottleneck of the Er 3+ 4 I 13/2 level. Moreover, consideration of the lifetimes alongside the absorption data of the individual ions indicates that despite the large absorption cross-section of Nd 3+ at 808 nm, the concentration needed to yield more absorbed power than utilizing direct 976 nm excitation of Er 3+ results in unfavorable lifetimes of the mid-infrared transition. In the end, Pr 3+ prevails as the superior co-dopant in terms of the effects on fluorescence lifetimes as well as potential laser system design considerations. In a unique self-doping approach, a reducing melt atmosphere of Ar instead of O 2 creates a small fraction of Ti 3+ . In 5Er 2 O 3 -12La 2 O 3 -83TiO 2 glass, the presence of Ti 3+ quenches the 4 I 13/2 emission about 2.6 times more than the 4 I 11/2 when lifetimes are compared to an O 2 melt environment. As an additional means of increasing the mid-infrared emission, the effect of temperature on the mid- and near- infrared lifetimes of a lightly doped lanthanum titanate composition is investigated between 77-300 K. The mid-infrared lifetime increases by ∼30% while the near-infrared lifetime increases by ∼10%, which suggests in addition to co-doping, active cooling of the gain media will further enhance performance.

Materials Science↗
DOE OSTI2025

Immersive Digital Twin Laboratory for Engineering Education (CRADA Final Report)

This project aimed to create an immersive digital twin laboratory that incorporates advanced tracking and visualization capabilities. In collaboration with Fort Lewis College, NREL designed a state-of-the-art physical visualization laboratory, developed a software platform to enable interaction with tracked physical objects in the laboratory, and provided proof-of-concept curricula that included manipulating these tracked objects. The project was initiated to address the growing need for innovative educational tools in engineering education. As renewable energy systems, particularly solar installations, become more complex, there is a pressing need to bridge the gap between theoretical knowledge and practical application. Traditional methods of teaching solar engineering concepts often fall short of providing students with a comprehensive, hands-on understanding. This immersive digital twin laboratory was conceived to fill that gap by creating a safe, non-energized setting where students can interact with augmented solar installation objects, gaining valuable insights into system performance, design, and maintenance. The project utilized extended reality (XR) technologies, including head-mounted displays (HMDs) and a whole-room optical motion tracking system, to connect physical objects with their digital twins in real time. The laboratory was equipped with MagicLeap 2 HMDs, supported by a Vicon Vero 2.2 Optical Tracking System, which provided precise 6-degrees-of-freedom (6-DOF) tracking. We developed a software platform to manage the interaction between the tracked physical objects and their virtual counterparts, enabling real-time data synchronization, object recognition, and virtual overlays. We designed the system to be flexible and extendable, allowing for future integration of additional objects and curriculum. This research advances the field of engineering education by demonstrating the potential of immersive digital twin environments. The laboratory provides a dynamic learning space where students can experiment, collaborate, and learn without the risks associated with live experimentation. The ability to simulate and manipulate solar installation objects under various conditions has broad implications for workforce development, particularly in renewable energy. The project also highlights the economic feasibility of using XR technologies in educational settings, offering a cost-effective solution for institutions looking to enhance their curriculum. By fostering a deeper understanding of solar energy systems, this work contributes to the broader goal of supporting the global energy transition and preparing the next generation of engineers and technicians.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1973

Lamp pumped Nd:YAG laser. Space-qualifiable Nd:YAG laser for optical communications

Results are given of a program concerned with the design, fabrication, and evaluation of alkali pump lamps for eventual use in a space qualified Nd:YAG laser system. The study included evaluation of 2mm through 6mm bore devices. Primary emphasis was placed upon the optimization of the 4mm bore lamp and later on the 6mm bore lamp. As part of this effort, reference was made to the Sylvania work concerned with the theoretical modeling of the Nd:YAG laser. With the knowledge gained, a projection of laser performance was made based upon realistic lamp parameters which should easily be achieved during following developmental efforts. Measurements were made on the lamp performance both in and out of the cavity configuration. One significant observation was that for a constant vapor pressure device, the spectral and fluorescent output did not vary for vacuum or argon environment. Therefore, the laser can be operated in an inert environment (eg. argon) with no degradation in output. Laser output of 3.26 watts at 430 watts input was obtained for an optimized 4mm bore lamp.

Ward, K. B.↗
NASA NTRS1974

Dual frequency dichroic feed performance

The NASA Deep Space Net (DSN) in support of the Viking Mars Project in 1976, and for science and technology demonstrations during the Mariner-Venus-Mercury mission in 1974, has developed and implemented a dual (S- and X-band) feed for large ground microwave antennas. This feed provides for a multiplicity of functions; very low listening capability at each downlink (spacecraft-to-earth) band as well as simultaneous diplexed very high cw power uplink (earth-to-spacecraft) at the S-band frequency. Total 64-m antenna system performance, is considered in terms of gain, operating noise temperature and dual beam pointing or boresight coincidence. Because of the unique ability to fold or stow the dual band feed elements for single band operations, the performance definition between single and dual band operations will be reliable and accurate.

Bathker, D. A.↗
NASA NTRS1974

Apollo 17 ultraviolet spectrometer experiment (S-169)

The scientific objectives of the ultraviolet spectrometer experiment are discussed, along with design and operational details, instrument preparation and performance, and scientific results. Information gained from the experiment is given concerning the lunar atmosphere and albedo, zodiacal light, astronomical observations, spacecraft environment, and the distribution of atomic hydrogen in the solar system and in the earth's atmosphere.

Fastie, W. G.↗
NASA NTRS1975

Fluid infusion system

Development of a fluid infusion system was undertaken in response to a need for an intravenous infusion device operable under conditions of zero-g. The initial design approach, pursued in the construction of the first breadboard instrument, was to regulate the pressure of the motive gas to produce a similar regulated pressure in the infusion liquid. This scheme was not workable because of the varying bag contact area, and a major design iteration was made. A floating sensor plate in the center of the bag pressure plate was made to operate a pressure regulator built into the bellows assembly, effectively making liquid pressure the directly controlled variable. Other design changes were made as experience was gained with the breadboard. Extensive performance tests were conducted on both the breadboard and the prototype device; accurately regulated flows from 6 m1/min to 100 m1/min were achieved. All system functions were shown to operate satisfactorily.

Hammond, J. C.↗
NASA NTRS1976

Flight data analysis and further development of variable-conductance heat pipes

Continuing efforts in large gains in heat-pipe performance are reported. It was found that gas-controlled variable-conductance heat pipes can perform reliably for long periods in space and effectively provide temperature stabilization for spacecraft electronics. A solution was formulated that allows the control gas to vent through arterial heat-pipe walls, thus eliminating the problem of arterial failure under load, due to trace impurities of noncondensable gas trapped in an arterial bubble during priming. This solution functions well in zero gravity. Another solution was found that allows priming at a much lower fluid charge. A heat pipe with high capacity, with close temperature control of the heat source and independent of large variations in sink temperature was fabricated.

Enginer, J. E.↗
NASA NTRS1976

A stop-restart solid propellant study with salt quench

Experiments were conducted to gain insight into the unsatisfactory performance of the salt quench system of solid propellants in earlier studies. Nine open-air salt spray tests were conducted and high-speed cinematographic coverage was obtained of the events. It is shown that the salt spray by the detonator is generally a two-step process yielding two different fractions. The first fraction consists of finely powdered salt and moves practically unidirectionally at a high velocity (thousand of feet per second) while the second fraction consists of coarse particles and moves randomly at a low velocity (a few feet per second). Further investigation is required to verify the speculation that a lower quench charge ratio (weight of salt/propellant burning area) than previously employed may lead to an efficient quench

Kumar, R. N.↗
NASA NTRS1977

Applications of remote sensing to water resources

Analyses were made of selected long-term (1985 and beyond) objectives, with the intent of determining if significant data-related problems would be encountered and to develop alternative solutions to any potential problems. One long-term objective selected for analysis was Water Availability Forecasting. A brief overview was scheduled in FY-77 of the objective -- primarily a fact-finding study to allow Data Management personnel to gain adequate background information to perform subsequent data system analyses. This report, includes discussions on some of the larger problems currently encountered in water measurement, the potential users of water availability forecasts, projected demands of users, current sensing accuracies, required parameter monitoring, status of forecasting modeling, and some measurement accuracies likely to be achievable by 1980 and 1990.

Source record↗
NASA NTRS1977

An implementable digital adaptive flight controller designed using stabilized single-stage algorithms

An explicit adaptive controller, which makes direct use of on-line parameter identification, has been developed and applied to both the linearized and nonlinear equations of motion for the F-8 aircraft. This controller is composed of an on-line weighted least squares parameter identifier, a Kalman state filter, and a real model following control law designed using single-stage performance indices. The corresponding control gains are readily adjustable in accordance with parameter changes to ensure asymptotic stability if the conditions of perfect model following are satisfied, and stability in the sense of boundedness otherwise. Simulation experiments with realistic measurement noise indicate that the controller was effective in compensating for parameter variations and capable of rapid recovery from a set of erroneous initial parameter estimates which defined a set of destabilizing gains.

Alag, G.↗
NASA NTRS1979

Utility operational experience on the NASA/DOE MOD-0A 200-kW wind turbine

The Mod-0A 200 wind turbine was designed and fabricated as part of the Federal Wind Energy Program. Early wind turbine operation and performance data were obtained while gaining initial experience in the operation of large, horizontal axis wind turbines in typical utility environments. The Mod-0A wind turbine was turned over to the Town of Clayton Light and Water Plant, Clayton, NM, for utility operation and on December 31, 1978, the machine had completed ten months of utility operation. The machine is described and the recent operational experience at Clayton, NMis documented.

Glasgow, J. C.↗
NASA NTRS1978

An Orbiting Standards Platform for communication satellite system RF measurements

The Orbiting Standards Platform (OSP) is a proposed satellite dedicated to performing RF measurements on space communications systems. It would consist of a quasi-geostationary spacecraft containing an ensemble of calibrated RF sources and field strength meters operating in several microwave bands, and would be capable of accurately and conveniently measuring critical earth station and satellite RF performance parameters, such as EIRP, gain, figure of merit (G/T), crosspolarization, beamwidth, and sidelobe levels. The feasibility and utility of the OSP concept has been under joint study by NASA, NBS, Comsat and NTIA. A survey of potential OSP users was conducted by NTIA as part of this effort. The response to this survey, along with certain trends in satellite communications system design, indicates a growing need for such a measurement service.

Wallace, R. G.↗
NASA NTRS1981

In orbit performance of the Einstein Observatory/HEAO-2 Imaging Proportional Counter

After two years of orbital operation, the IPC - a soft X-ray (0.2-4 keV) position sensitive proportional counter - continues to perform well after some initial gain changes, and is the most widely used focal plane instrument of the Einstein Observatory. X-ray images of several thousand cosmic X-ray sources have been obtained with a resolution of about 1.5 arcmin (FWHM) with a 1-deg field. Particle backgrounds are less than expected. The calibration of the instrument with respect to gain variations and spatial linearity is being refined by in-flight measurements.

Gorenstein, P.↗
NASA NTRS1982

Wide-band diffraction improved dual-shaped reflectors

Modified dual-shaped reflectors are discussed. These antennas have improved gain and gain over noise temperature (G/T) performance over the conventional uniform illumination design when diffraction effects are considered. A further advantage of the present design approach is its inherent broad-band characteristics. These considerations are vital for ultra-low noise systems as employed in the deep space telemetry service.

Cha, A. G.↗
NASA NTRS1983

Stability analysis of a buck regulator employing input filter compensation

The interaction between the input filter and the regulator often causes serious degradation of performance. The reduction in loop gain due to input filter interaction can result in system instability. An exact stability analysis of the buck regulator system is presented. The input filter parameter values are varied and system instability is predicted for the case without feedforward. The eigenvalues of the system can be brought back into the unit circle and the system thus stabilized with the addition of the feedforward loop. Measurements made for the cases with and without feedforward confirm the analytical prediction.

Kelkar, S. S.↗