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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 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Bimetallic Copper/Ruthenium/Osmium Complexes: Observation of Conformational Differences Between the Solution Phase and Solid State by Atomic Pair Distribution Function Analysis

High-energy X-ray scattering and pair distribution function analysis (HEXS/PDF) is a powerful method to reveal the structure of materials lacking long-range order, but is underutilized for molecular complexes in solution. Here we demonstrate the application of HEXS/PDF with 0.26 Å resolution to uncover the solution structure of five bimetallic Cu I /Ru II /Os II complexes. HEXS/PDF of each complex in acetonitrile solution confirms the pairwise distances in the local coordination sphere of each metal center as well as the metal...metal distances separated by over 12 Å. The metal…metal distance detected in solution is compared with that from the crystal structure and molecular models to confirm that distortions to the metal bridging ligand are unique to the solid state. This work presents the first example of observing sub-Ångström conformational differences by direct comparison of solution phase and solid-state structures and shows the potential for HEXS/PDF in the determination of solution structure of single molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2000

Aerodynamic Database Development for the Hyper-X Airframe Integrated Scramjet Propulsion Experiments

This paper provides an overview of the activities associated with the aerodynamic database which is being developed in support of NASA's Hyper-X scramjet flight experiments. Three flight tests are planned as part of the Hyper-X program. Each will utilize a small, nonrecoverable research vehicle with an airframe integrated scramjet propulsion engine. The research vehicles will be individually rocket boosted to the scramjet engine test points at Mach 7 and Mach 10. The research vehicles will then separate from the first stage booster vehicle and the scramjet engine test will be conducted prior to the terminal decent phase of the flight. An overview is provided of the activities associated with the development of the Hyper-X aerodynamic database, including wind tunnel test activities and parallel CFD analysis efforts for all phases of the Hyper-X flight tests. A brief summary of the Hyper-X research vehicle aerodynamic characteristics is provided, including the direct and indirect effects of the airframe integrated scramjet propulsion system operation on the basic airframe stability and control characteristics. Brief comments on the planned post flight data analysis efforts are also included.

Engelund, Walter C.↗
NASA NTRS2002

Multi-mission telecom analysis tool

In the early formulation phase of a mission it is critically important to have fast, easy to use, easy to integrate space vehicle subsystem analysis tools so that engineers can rapidly perform trade studies not only by themselves but in coordination with other subsystem engineers as well. The Multi-Mission Telecom Analysis Tool (MMTAT) is designed for just this purpose.

technical keyboards↗
NASA NTRS2011

Saturn Ring Data Analysis and Thermal Modeling

CIRS, VIMS, UVIS, and ISS (Cassini's Composite Infrared Specrtometer, Visual and Infrared Mapping Spectrometer, Ultra Violet Imaging Spectrometer and Imaging Science Subsystem, respectively), have each operated in a multidimensional observation space and have acquired scans of the lit and unlit rings at multiple phase angles. To better understand physical and dynamical ring particle parametric dependence, we co-registered profiles from these three instruments, taken at a wide range of wavelengths, from ultraviolet through the thermal infrared, to associate changes in ring particle temperature with changes in observed brightness, specifically with albedos inferred by ISS, UVIS and VIMS. We work in a parameter space where the solar elevation range is constrained to 12 deg - 14 deg and the chosen radial region is the B3 region of the B ring; this region is the most optically thick region in Saturn's rings. From this compilation of multiple wavelength data, we construct and fit phase curves and color ratios using independent dynamical thermal models for ring structure and overplot Saturn, Saturn ring, and Solar spectra. Analysis of phase curve construction and color ratios reveals thermal emission to fall within the extrema of the ISS bandwidth and a geometrical dependence of reddening on phase angle, respectively. Analysis of spectra reveals Cassini CIRS Saturn spectra dominate Cassini CIRS B3 Ring Spectra from 19 to 1000 microns, while Earth-based B Ring Spectrum dominates Earth-based Saturn Spectrum from 0.4 to 4 microns. From our fits we test out dynamical thermal models; from the phase curves we derive ring albedos and non-lambertian properties of the ring particle surfaces; and from the color ratios we examine multiple scattering within the regolith of ring particles.

Saturn's rings↗
DOE OSTI2017

Probing the oxidation kinetics of small permalloy particles

The oxidation of permalloys is important to apply in a wide range. The oxidation and diffusion mechanisms of small permalloy particles with different Fe content are studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. Fe{sub 2}O{sub 3}/(Ni, Fe){sub 3}O{sub 4} plays a key role in the morphology evolution and diffusion mechanisms of small NiFe particles upon oxidation. The activation energies of grain boundary diffusion for the NiFe alloys increase from 141 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to ~50 wt%. We have developed a diffusion process resolved temperature programed oxidation (PR-TPO) analysis method. Three diffusion mechanisms have been recognized by using this method: In addition to the grain boundary diffusion and lattice diffusion, our TGA analysis suggests that the phase conversion from Fe{sub 2}O{sub 3} to (Ni, Fe){sub 3}O{sub 4} induces diffusion change and affects the diffusion process at the intermediate temperature. Relevant oxidation kinetics and diffusion mechanisms are discussed. - Graphical abstract: The oxidation mechanisms of small Permalloy particles with different Fe content is studied by using thermal gravimetric analysis (TGA) and microstructure characterizations. The activation energies of grain boundary diffusion for the NiFe alloys increases from 140 kJ/mol to 208 kJ/mol as the Fe content increases from 0 to 50 wt% as determined by TGA. We have developed a diffusion process resolved temperature programed oxidation (DPR-TPO) analysis method, and three diffusion mechanisms have been recognized by using this method: In addition to the well-known grain boundary diffusion and lattice diffusion, we found that the phase conversion from Fe{sub 2}O{sub 3} to (Ni, Fe){sub 3}O{sub 4} will induce diffusion changes and affect the diffusion process at the intermediate temperature. The diffusion processes can be characterized by the corresponding characteristic peak temperatures in temperature programmed oxidation (TPO) analysis. This work not only give insight knowledge about the oxidation and diffusion processes of small permalloy particles, but also, provides a useful tool for analyzing solid-gas reactions of other materials. - Highlights: • The oxidation kinetics of small NiFe particles were studied by using thermoanalysis. • Grain boundary, lattice, and phase conversion induced diffusions were recognized. • The activation energy of oxidation increases with the Fe content in the alloy. • Each diffusion process corresponds to a characteristic temperature in TPO analysis. • NiFe alloys with ~5–10 wt% Fe content have the lowest oxidation rates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

In situ high-temperature X-ray diffraction study of Sc-doped titanium oxide nanocrystallites

Titanium dioxide is an inexpensive wide-gap highly ionic semiconductor with striking photocatalytic capabilities in several heterogeneous photoredox reactions. A small crystal size is desirable to maximize the surface area, since photocatalytic reactions occur at the surface of a photocatalyst. Presented in this work are the synthesis and microstructural characterization of 4 at.% Sc-doped TiO 2 (4SDT) prepared by water-based co-precipitation. The crystal structure of 4SDT was examined via in situ high-temperature powder X-ray diffraction experiments from 25 to 1200°C. Rietveld analysis revealed single-phase anatase up to 875°C, while at 900°C the anatase-to-rutile phase transformation occurred and at higher temperatures additional reflections of Sc-rich phases (Sc 2 TiO 5 from 975°C and Ti 3 Sc 4 O 12 or Sc 2 O 3 at 1200°C) were observed. Debye function analysis (DFA) was applied to model the total scattering pattern directly in reciprocal space, allowing the reconstruction of Ti vacancies. Both Rietveld and DFA methods were applied to estimate the nanocrystallite size and shape with consistent growth in crystallite size with temperature: an ellipsoid shape with equatorial ~4.7 nm / axial (001) ~6.9 nm at 25°C to equatorial ~27.9 nm / axial (001) ~39.6 nm at 900°C refined by Rietveld analysis, versus a cylinder shape with D a , b = 4.3 nm and size dispersion σ ab = 1.5 nm, L c = 4.9 nm and σ c = 2.3 nm at 25°C to D a , b = 21.4 nm, σ ab = 8.3 nm, L c = 23.9 and σ c = 10.9 nm at 900°C estimated by DFA. The microstructural changes obtained by Rietveld and DFA methods were supported by high-resolution transmission electron microscopy image analysis, as well as by the less direct nitrogen sorption techniques that provide information on the size of non-agglomerated and dense particles. The Ti site-occupancy factor showed a linear increase from 0.6–0.8 at 25°C to unity at 900°C for anatase, and from ~0.7 at 900°C to unity at 1200°C for rutile, via Rietveld analysis and DFA.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Summertime ozone pollution in China affected by stratospheric quasi-biennial oscillation

In recent years, the near-surface ozone (O 3 ) level has been rising fast in China, with increasing damage to human health and ecosystems. In this study, the impact of stratospheric quasi-biennial oscillation (QBO) on interannual variations in summertime tropospheric O 3 over China is investigated based on GEOS-Chem model simulations and satellite retrievals. QBO has a significant positive correlation with near-surface O 3 concentrations over central China (92.5–112.5° E, 26–38° N) when the sea surface temperature (SST) over the eastern tropical Pacific is warmer than normal, with a correlation coefficient of 0.53, but QBO has no significant effect on O 3 under the cold SST anomaly. Compared to the easterly phase of QBO, the near-surface O 3 concentrations have an increase of up to 3 ppb (5% relative to the average) over central China during its westerly phase under the warm SST anomaly. O 3 also increases above the surface and up to the upper troposphere, with a maximum increase of 2–3 ppb (3%–5%) in 850–500 hPa over central China when comparing westerly phase to easterly phase. Process-based analysis and sensitivity simulations suggest that the O 3 increase over central China is mainly attributed to the anomalous downward transport of O 3 during the westerly phase of QBO when a warm SST anomaly occurs in the eastern tropical Pacific, while the local chemical reactions and horizontal transport processes partly offset the O 3 increase. This work suggests a potentially important role of QBO and the related vertical transport process in affecting near-surface O 3 air quality, with an indication for O 3 pollution prediction and prevention.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

ADROC: An Emulation Experimentation Platform for Advancing Resilience of Control Systems

Cyberattacks against industrial control systems have increased over the last decade, making it more critical than ever for system owners to have the tools necessary to understand the cyber resilience of their systems. However, existing tools are often qualitative, subject matter expertise-driven, or highly generic, making thorough, data-driven cyber resilience analysis challenging. The ADROC project proposed to develop a platform to enable efficient, repeatable, data-driven cyber resilience analysis for cyber-physical systems. The approach consists of two phases of modeling: computationally efficient math modeling and high-fidelity emulations. The first phase allows for scenarios of low concern to be quickly filtered out, conserving resources available for analysis. The second phase supports more detailed scenario analysis, which is more predictive of real-world systems. Data extracted from experiments is used to calculate cyber resilience metrics. ADROC then ranks scenarios based on these metrics, enabling prioritization of system resources to improve cyber resilience.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2000

Stardust Navigation Covariance Analysis

The Stardust spacecraft was launched on February 7, 1999 aboard a Boeing Delta-II rocket. Mission participants include the National Aeronautics and Space Administration (NASA), the Jet Propulsion Laboratory (JPL), Lockheed Martin Astronautics (LMA) and the University of Washington. The primary objective of the mission is to collect in-situ samples of the coma of comet Wild-2 and return those samples to the Earth for analysis. Mission design and operational navigation for Stardust is performed by the Jet Propulsion Laboratory (JPL). This paper will describe the extensive JPL effort in support of the Stardust pre-launch analysis of the orbit determination component of the mission covariance study. A description of the mission and it's trajectory will be provided first, followed by a discussion of the covariance procedure and models. Predicted accuracy's will be examined as they relate to navigation delivery requirements for specific critical events during the mission. Stardust was launched into a heliocentric trajectory in early 1999. It will perform an Earth Gravity Assist (EGA) on January 15, 2001 to acquire an orbit for the eventual rendezvous with comet Wild-2. The spacecraft will fly through the coma (atmosphere) on the dayside of Wild-2 on January 2, 2004. At that time samples will be obtained using an aerogel collector. After the comet encounter Stardust will return to Earth when the Sample Return Capsule (SRC) will separate and land at the Utah Test Site (UTTR) on January 15, 2006. The spacecraft will however be deflected off into a heliocentric orbit. The mission is divided into three phases for the covariance analysis. They are 1) Launch to EGA, 2) EGA to Wild-2 encounter and 3) Wild-2 encounter to Earth reentry. Orbit determination assumptions for each phase are provided. These include estimated and consider parameters and their associated a-priori uncertainties. Major perturbations to the trajectory include 19 deterministic and statistical maneuvers planned for the mission. The spacecraft is three axis stabilized and has unbalanced thrusters for attitude control. Accelerations due to the attitude control system are treated stochastically. The tracking scenario for the study is patterned after the actual schedule employed during the different phases of the mission. Conventional X-band two-way Doppler and SRA range data was simulated and the standard accuracy for these data types was assumed throughout most of the mission. However, a deweighting scheme was used for the Doppler data during times of low Sun-Earth-Probe angles, especially in the case of the DSM. Optical data is assumed to be available starting at 50 days prior to the comet encounter. The optical data will be used to improve the ephemeris of Wild-2, which is considered crucial to properly target the comet flyby. Results of the covariance analysis are presented for all mission phases. Navigation capability will be discussed in terms of the uncertainty in the encounter B-Plane (B.R and B.T) and linearized time of flight. Delivery errors based on the final maneuver prior to the comet encounter will be presented. The most stringent navigation requirement is for the Earth reentry. The uncertainty in the flight path angle must be less than 0.02 degree (orbit determination and maneuver performance) to assure successful recovery of the SRC. Results presented show that this requirement can be met.

Menon, Premkumar R.↗
DOE OSTI2022

Quantitative measurements of density in shock-compressed silver up to 330 GPa using x-ray diffraction

This work presents a structural study of shock-compressed states in Ag to 331 GPa, accessed via laser shock compression. Structures of the resulting crystalline phases and the average atomic distribution of the liquid state are determined using in situ x-ray diffraction. We employ structure factor analysis, adapted for a non-monochromatic x-ray source, to determine the density of the liquid phase from analysis of x-ray diffraction data for the first time in shock compressed Ag. We also present a detailed analysis of the crystalline phases, which shows good agreement with the phase boundaries reported in previous experimental and theoretical works. We utilize the whole powder pattern fitting approach implemented in the MAUD package to constrain stacking faults in the face centered cubic structure. We observe the ambient fcc structure up to a stress of 146 GPa before a transition to a body-centered cubic structure and liquid phase at 179 GPa, with full melting above 212 GPa.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Simulations of single- and two-phase shock tubes and gravity-driven wave problems with the RELAP-7 nuclear reactor system analysis code

Propagation of pressure waves in single and two-phase flows is of key interest for nuclear safety analyses, reactor design, construction and life extension of nuclear reactors. In this work, we assess the capabilities of RELAP-7, the next-generation nuclear reactor system code, to solve single- and two-phase flows developing pressure waves. RELAP-7 is based on a 7-equation, two-phase flow model, with distinct phasic pressures. It is well established that these hyperbolic conservation laws can develop shocks and discontinuities and thus, require a stabilization numerical method. The all-Mach flow Entropy Viscosity Method (EVM) is now employed in RELAP-7 as a viscous stabilization approach. In this paper, we briefly describe the implementation of the EVM and use open-literature test cases that exhibit pressure waves to show that the entropy viscosity method performs adequately for these single- and two-phase cases.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

Appalachian Basin Play Fairway Analysis Analyses and Results

*This submission updates a 2015 submission for the utilization analysis (https://gdr.openei.org/submissions/623)* The files document the analysis of utilization potential in support of Phase 1 Low Temperature Geothermal Play Fairway Analysis for the Appalachian Basin. This 2016 submission includes data pertinent to the methods and results of an analysis of the Surface Levelized Cost of Heat (SLCOH) for US Census Bureau 'Places' within the study area. The SLCOHis was calculated using a modification of a program called GEOPHIRES, available at http://koenraadbeckers.net/geophires/index.php. In addition to calculating SLCOH, this task also identified many industrial sites that may be prospects for use of a geothermal district heating system, based on their size and industry, rather than on the SLCOH. An industry sorted listing and maps of the sites have been plotted as a layer onto different iterations of maps combining the three geologic risk factors (Thermal Quality, Natural Reservoir Quality, and Risk of Seismicity). In addition, a shapefile of the industrial sites is also included with 7 associated files. Supporting files are also supplied.

15 GEOTHERMAL ENERGY↗
NASA NTRS1970

Development of a test and flight engineering oriented language, phase 3

Based on an analysis of previously developed test oriented languages and a study of test language requirements, a high order language was designed to enable test and flight engineers to checkout and operate the proposed space shuttle and other NASA vehicles and experiments. The language is called ALOFT (a language oriented to flight engineering and testing). The language is described, its terminology is compared to similar terms in other test languages, and its features and utilization are discussed. The appendix provides the specifications for ALOFT.

Kamsler, W. F.↗