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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Electrically Engaged UnduLation (EEL) Marine Energy System

Current technologies at the forefront of instrumentation for ocean observation through acoustic mapping are powered by batteries that cannot achieve the lasting durations required for high-resolution measurements. Pyro-E has designed an Electrically Engaged unduLation (EEL) system capable of in situ energy harvest and deployment in sub-sea configurations. By extracting kinetic energy from the ocean, EEL proposes to provide power output ranging from 1 mW to 1,000 mW. Such a magnitude of power can sustain active instrumentation with onboard processing of data and over-the-horizon telemetry. Pyro-E and Oak Ridge National Laboratory have utilized software tools and powerful computing resources to develop a techno-economic design of the EEL capable of harvesting 5 W. The material response of the EEL under simulated hydromechanical loads is described through time-accurate predictions. All physical tests were conducted by Pyro-E to guide simulations at Oak Ridge National Laboratory.

16 TIDAL AND WAVE POWER↗
DOE OSTI2024

Mercury Modeling of TREAT Big-BUSTER Free Field Characterization Experiments

This report summarizes modeling of Big-BUSTER free field characterization (FFC) experiments at the Idaho National Laboratory (INL) Transient Reactor Test Facility (TREAT) reactor performed from December 20th, 2023, to February 22nd, 2024. TREAT is an air-cooled graphite moderated research reactor that can be used to study material response to neutron irradiation. The BUSTER (Broad Use Specimen Transient Experiment Rig) refers to a containment module for placing experiments in the reactor core. The Big-BUSTER is an analogous platform for a modified core configuration with a larger experimental cavity.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Finite Element Analysis of the TRUST Nonlinear Dynamics Testbed

This paper builds on prior work conducted within the Los Alamos National Laboratory (LANL) Testbeds to Reduce Uncertainty in Simulations and Tests (TRUST) program. Specifically, it builds on finite element (FE) modeling efforts for the TRUST program’s Nonlinear Dynamics (ND) testbed. Historically, the FE model for the ND testbed has exclusively utilized a Lanczos eigensolver that linearly extracts the system’s natural frequencies. This paper investigates the Abaqus 2024’s explicit dynamic solver, which implements a central difference explicit solver. The central difference method used in Abaqus can capture nonlinear material responses in structural dynamic simulations making it suitable for the ND FE model.

42 ENGINEERING↗
DOE OSTI2022

In-Situ Sensing and Dynamics Predictions for Electrothermally-Actuated Soft Robot Limbs

Untethered soft robots that locomote using electrothermally-responsive materials like shape memory alloy (SMA) face challenging design constraints for sensing actuator states. At the same time, modeling of actuator behaviors faces steep challenges, even with available sensor data, due to complex electrical-thermal-mechanical interactions and hysteresis. This article proposes a framework for in-situ sensing and dynamics modeling of actuator states, particularly temperature of SMA wires, which is used to predict robot motions. A planar soft limb is developed, actuated by a pair of SMA coils, that includes compact and robust sensors for temperature and angular deflection. Data from these sensors are used to train a neural network-based on the long short-term memory (LSTM) architecture to model both unidirectional (single SMA) and bidirectional (both SMAs) motion. Predictions from the model demonstrate that data from the temperature sensor, combined with control inputs, allow for dynamics predictions over extraordinarily long open-loop timescales (10 min) with little drift. Prediction errors are on the order of the soft deflection sensor’s accuracy. This architecture allows for compact designs of electrothermally-actuated soft robots that include sensing sufficient for motion predictions, helping to bring these robots into practical application.

Sabelhaus, Andrew P.↗
DOE OSTI2016

IC 751: A new changing look AGN discovered by NusTAR

We present results of five Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/X-Ray Telescope. We find that the nuclear X-ray source underwent a clear transition from a Compton-thick (N{sub H}≃2×10{sup 24} cm{sup −2}) to a Compton-thin (N{sub H}≃4×10{sup 23} cm{sup −2}) state on timescales of ≲3 months, which makes IC 751 the first changing look AGN discovered by NuSTAR. Changes of the line of sight column density at the ∼2σ level are also found on a timescale of ∼48 hr (ΔN{sub H}∼10{sup 23} cm{sup −2}). From the lack of spectral variability on timescales of ∼100 ks, we infer that the varying absorber is located beyond the emission-weighted average radius of the broad-line region (BLR), and could therefore be related either to the external part of the BLR or a clumpy molecular torus. By adopting a physical torus X-ray spectral model, we are able to disentangle the column density of the non-varying absorber (N{sub H}∼3.8×10{sup 23} cm{sup −2}) from that of the varying clouds [N{sub H}∼ (1−150) × 10{sup 22} cm{sup −2}], and to constrain that of the material responsible for the reprocessed X-ray radiation (N{sub H}∼6×10{sup 24} cm{sup −2}). We find evidence of significant intrinsic X-ray variability, with the flux varying by a factor of five on timescales of a few months in the 2–10 and 10–50 keV band.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Limits on X-Ray Polarization at the Core of Centaurus A as Observed with the Imaging X-Ray Polarimetry Explorer

We present measurements of the polarization of X-rays in the 2–8 keV band from the nucleus of the radio galaxy Centaurus A (Cen A), using a 100 ks observation from the Imaging X-ray Polarimetry Explorer (IXPE). Nearly simultaneous observations of Cen A were also taken with the Swift, NuSTAR, and INTEGRAL observatories. No statistically significant degree of polarization is detected with IXPE. These observations have a minimum detectable polarization at 99% confidence (MDP 99 ) of 6.5% using a weighted, spectral model-independent calculation in the 2–8 keV band. The polarization angle ψ is consequently unconstrained. Spectral fitting across three orders of magnitude in X-ray energy (0.3–400 keV) demonstrates that the SED of Cen A is well described by a simple power law with moderate intrinsic absorption (N H ~ 10 23 cm -2 ) and a Fe Kα emission line, although a second unabsorbed power law is required to account for the observed spectrum at energies below 2 keV. This spectrum suggests that the reprocessing material responsible for this emission line is optically thin and distant from the central black hole. Our upper limits on the X-ray polarization are consistent with the predictions of Compton scattering, although the specific seed photon population responsible for the production of the X-rays cannot be identified. The low polarization degree, variability in the core emission, and the relative lack of variability in the Fe Kα emission line support a picture where electrons are accelerated in a region of highly disordered magnetic fields surrounding the innermost jet.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Beam-Material Interaction

Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high-intensity energetic particle beam interactions with accelerator, generic target, and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and environment in challenging current and future applications.

43 PARTICLE ACCELERATORS↗
NASA NTRS1965

Flight reentry experiments

The foregoing discussion has show the way in which flight testing supplements, extends, and reinforces the usefulness of data from ground test facilities. Flight tests can provide an anchor point in evaluating ground test data. Although flight tests can avoid some of the inherent problems of ground facilities, they are expensive, putting a premium on each test to provide the most data that can be acquired. The portions of the reentry flight spectrum which can be simulated by "hot" and "cold" ground facilities are reviewed and some of the current flight programs for obtaining data in the Apollo Reentry Envelope are discussed. The programs are categorized as to (1) environment (heating), (2) materials response, (3) communication problems, and (4) observables. A discussion of the launch vehicles, unknown parameters, and methods of data acquisition for each program is presented.

Radio Attenuation↗
NASA NTRS1969

Laser display systems. II.

Holographic displays using ultrasonic vibrations or laser outputs as optical sources, discussing recording materials, responses and computer applications

Devaney, A. J.↗
NASA NTRS1970

Analysis of surface ablation of noncharring materials

Computer program solves combined problem of heat transfer and material response for the stagnation region of blunt bodies experiencing melting and vaporizing or subliming ablation. Program contains formulas for the transitional regime to bridge between the free-molecule and continuum regimes.

Matting, F. W.↗
NASA NTRS1971

Gravity flow of powder in a lunar environment. Part 2: Analysis of flow initiation

A small displacement-small strain finite element technique utilizing the constant strain triangle and incremental constitutive equations for elasticplastic (media nonhardening and obeying a Coulomb yield condition) was applied to the analysis of gravity flow initiation. This was done in a V-shaped hopper containing a powder under lunar environmental conditions. Three methods of loading were examined. Of the three, the method of computing the initial state of stress in a filled hopper prior to drawdown, by adding material to the hopper layer by layer, was the best. Results of the analysis of a typical hopper problem show that the initial state of stress, the elastic moduli, and the strength parameters have an important influence on material response subsequent to the opening of the hopper outlet.

Pariseau, W. G.↗
NASA NTRS1973

Arc jet tests of RSI materials: Screening and comparative evaluation

Cyclic convective heating test results show that all surface insulation materials tested exhibit a wide range of surface emittance and catalytic activity depending on their surface coatings. Coatings have a significant effect on the overall material response depending on boundary layer characteristics.

Schaefer, J. W.↗
NASA NTRS1973

The infrared spectrum and angular size of Eta Carinae.

The angular size of the infrared source associated with the peculiar optical object Eta Carinae was measured at wavelengths from 2.2 to 18 microns. The angular diameter, which is 2 arc sec at 2.2 microns, is found to increase with increasing wavelength to 6 arc sec at 10 to 18 microns. The solid materials responsible for the thermal radiation have a temperature of roughly 425 K in the inner shell, and 250 K in the outer region. The observed bolometric magnitude of -11.5 is mostly produced by the cool shell, which in turn must be powered by absorption of shortwave radiation emitted by a central object of corresponding bolometric magnitude.

Gehrz, R. D.↗
NASA NTRS1974

Volume reflecting heat shields for entry into the giant planet atmospheres

The performance of a volume reflecting or backscattering silica heat shield is examined for an entry probe into the severe radiative environments of Saturn, Uranus, and Jupiter. The governing equations for the material response are solved numerically and include the effects of temperature-dependent thermal properties, temperature- and wavelength-dependent radiative properties, and surface recession caused by thermochemical ablation. The influence of the scattering properties on backface temperature is examined, and results are presented which show the required heat-shield thickness for the entry trajectories selected.

Howe, J. T.↗
NASA NTRS1975

Physical nature of the climatic and biological effects of the Peru current

Surface and depth flow processes and their effects on the behavior of the Peru current are considered in relation to climatological and biological effects for the entire western coast of South America. The mean annual coastal air temperature is from 2 deg to 6 deg below the norm and precipitation is extremely rare. An upwelling effect brings up the cold deep waters with their rich content of organic material responsible for the huge biological productivity of the region.

Gusev, A. M.↗