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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 1,513 records · Page 84
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Test and evaluation of the Navy half-watt RTG

The radioisotope thermoelectric generator (RTG) considered is to provide a continuous minimum power output of 0.5 watt at 6.0 to 8.5 volts for a minimum period of 15 years. The mechanical-electrical evaluation phase discussed involved the conduction of shock and vibration tests. The thermochemical-physical evaluation phase consisted of an analysis of the materials and the development of a thermal model. The thermoelectric evaluation phase included the accelerated testing of the thermoelectric modules.

Rosell, F. E., Jr.↗
NASA NTRS2019

Automatic Execution of Collision Avoidance and Return to Course Analysis (D.6.20) Experiment Review

This presentation details the experimental design for an upcoming engineering analysis of a mock version of the Airborne Collision Avoidance System (ACAS), specifically the 'Xu' variant, which is designed for unmanned aircraft platforms. As a component of the Unmanned Aircraft System (UAS) Integration into the National Airspace System (NAS) project, this engineering analysis intends to study aspects of ACAS Xu in two parts. In the first phase of the study, the display and alerting guidance for collision avoidance (CA) resolution advisories (RA) shown to pilots at a ground control station will be manipulated, varying in level of RA transparency and presentation of safe maneuver parameters. The second phase of the engineering analysis will examine pilots' response to increasing levels of automation in the tasks of collision avoidance and return-to-course (RTC).

Sadler, Garrett↗
DOE OSTI2016

Effect of Zn-doping on structural and magnetic properties of copper ferrite nanoparticles

The nanoparticles of CuFe{sub 2}O{sub 4} (CF) and Cu{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} (CZF) were synthesized using co-precipitation method to study the effect of Zn doping in Cu-ferrite. The X-ray diffraction (XRD) patterns were well fitted with two-phase structure using Rietveld analysis as Fd-3 m space group (spinel system) and C12/c1 space group (monoclinic system CuO-phase). The average crystallite size of the CF and CZF nanoparticles for spinel structure are 6 and 7 nm respectively. The spinel phase fraction is increased from 56% to 71% with Zn-doping of 20% in CF. The transmission electron micrograph analysis showed the narrow size distribution for CZF nanoparticles. The magnetization plots as a function of magnetic field (M (H)) of CF and CZF nanoparticles indicate superparamagnetic behavior. The magnetization is increased with Zn-doping in CF. The stable spinel Cu-ferrite can be obtained with Zn-doping in CF.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS2023

X-Ray Polarimetry of the Accreting Pulsar GX 301-2

The phase- and energy-resolved polarization measurements of accreting X-ray pulsars (XRPs) allow us to test different theoretical models of their emission, and they also provide an avenue to determine the emission region geometry. We present the results of the observations of the XRPGX 301−2 performed with the Imaging X-ray Polarimetry Explorer (IXPE). A persistent XRP, GX 301−2 has one of the longest spin periods known:∼680 s. A massive hyper-giant companion star Wray 977 supplies mass to the neutron star via powerful stellar winds. We did not detect significant polarization in the phase-averaged data when using spectropolarimetric analysis, with the upper limit on the polarization degree (PD)of 2.3% (99% confidence level). Using the phase-resolved spectropolarimetric analysis, we obtained a significant detection of polarization (above99% confidence level) in two out of nine phase bins and a marginal detection in three bins, with a PD ranging between∼3% and∼10% and a polarization angle varying in a very wide range from∼0◦to∼160◦. Using the rotating vector model, we obtained constraints on the pulsar geometry using both phase-binned and unbinned analyses, finding excellent agreement. Finally, we discuss possible reasons for a low observed polarization in GX 301−2.

GX 301-2, polarization, X-ray, X-ray binary, pulsa↗
DOE OSTI2021

Deep Learning Segmentation of Complex Features in Atomic-Resolution Phase-Contrast Transmission Electron Microscopy Images

Phase-contrast transmission electron microscopy (TEM) is a powerful tool for imaging the local atomic structure of materials. TEM has been used heavily in studies of defect structures of two-dimensional materials such as monolayer graphene due to its high dose efficiency. However, phase-contrast imaging can produce complex nonlinear contrast, even for weakly scattering samples. It is, therefore, difficult to develop fully automated analysis routines for phase-contrast TEM studies using conventional image processing tools. For automated analysis of large sample regions of graphene, one of the key problems is segmentation between the structure of interest and unwanted structures such as surface contaminant layers. In this study, we compare the performance of a conventional Bragg filtering method with a deep learning routine based on the U-Net architecture. We show that the deep learning method is more general, simpler to apply in practice, and produces more accurate and robust results than the conventional algorithm. We provide easily adaptable source code for all results in this paper and discuss potential applications for deep learning in fully automated TEM image analysis.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

MILK : a Python scripting interface to MAUD for automation of Rietveld analysis

Modern diffraction experiments ( e.g. in situ parametric studies) present scientists with many diffraction patterns to analyze. Interactive analyses via graphical user interfaces tend to slow down obtaining quantitative results such as lattice parameters and phase fractions. Furthermore, Rietveld refinement strategies ( i.e. the parameter turn-on-off sequences) tend to be instrument specific or even specific to a given dataset, such that selection of strategies can become a bottleneck for efficient data analysis. Managing multi-histogram datasets such as from multi-bank neutron diffractometers or caked 2D synchrotron data presents additional challenges due to the large number of histogram-specific parameters. To overcome these challenges in the Rietveld software Material Analysis Using Diffraction ( MAUD ), the MAUD Interface Language Kit ( MILK ) is developed along with an updated text batch interface for MAUD . The open-source software MILK is computer-platform independent and is packaged as a Python library that interfaces with MAUD . Using MILK , model selection ( e.g. various texture or peak-broadening models), Rietveld parameter manipulation and distributed parallel batch computing can be performed through a high-level Python interface. A high-level interface enables analysis workflows to be easily programmed, shared and applied to large datasets, and external tools to be integrated with MAUD . Through modification to the MAUD batch interface, plot and data exports have been improved. The resulting hierarchical folders from Rietveld refinements with MILK are compatible with Cinema: Debye–Scherrer , a tool for visualizing and inspecting the results of multi-parameter analyses of large quantities of diffraction data. In this manuscript, the combined Python scripting and visualization capability of MILK is demonstrated with a quantitative texture and phase analysis of data collected at the HIPPO neutron diffractometer.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1982

Improvement of Rocket Engine Plume Analysis Techniques

A nozzle plume flow field code was developed. The RAMP code which was chosen as the basic code is of modular construction and has the following capabilities: two phase with two phase transonic solution; a two phase, reacting gas (chemical equilibrium reaction kinetics), supersonic inviscid nozzle/plume solution; and is operational for inviscid solutions at both high and low altitudes. The following capabilities were added to the code: a direct interface with JANNAF SPF code; shock capturing finite difference numerical operator; two phase, equilibrium/frozen, boundary layer analysis; a variable oxidizer to fuel ratio transonic solution; an improved two phase transonic solution; and a two phase real gas semiempirical nozzle boundary layer expansion.

Smith, S. D.↗
DOE OSTI2024

Metagenome-assembled genomes provide insight into the metabolic potential during early production of Hydraulic Fracturing Test Site 2 in the Delaware Basin

Demand for natural gas continues to climb in the United States, having reached a record monthly high of 104.9 billion cubic feet per day (Bcf/d) in November 2023. Hydraulic fracturing, a technique used to extract natural gas and oil from deep underground reservoirs, involves injecting large volumes of fluid, proppant, and chemical additives into shale units. This is followed by a “shut-in” period, during which the fracture fluid remains pressurized in the well for several weeks. The microbial processes that occur within the reservoir during this shut-in period are not well understood; yet, these reactions may significantly impact the structural integrity and overall recovery of oil and gas from the well. To shed light on this critical phase, we conducted an analysis of both pre-shut-in material alongside production fluid collected throughout the initial production phase at the Hydraulic Fracturing Test Site 2 (HFTS 2) located in the prolific Wolfcamp formation within the Permian Delaware Basin of west Texas, USA. Specifically, we aimed to assess the microbial ecology and functional potential of the microbial community during this crucial time frame. Prior analysis of 16S rRNA sequencing data through the first 35 days of production revealed a strong selection for a Clostridia species corresponding to a significant decrease in microbial diversity. Here, we performed a metagenomic analysis of produced water sampled on Day 33 of production. This analysis yielded three high-quality metagenome-assembled genomes (MAGs), one of which was a Clostridia draft genome closely related to the recently classified Petromonas tenebris. This draft genome likely represents the dominant Clostridia species observed in our 16S rRNA profile. Annotation of the MAGs revealed the presence of genes involved in critical metabolic processes, including thiosulfate reduction, mixed acid fermentation, and biofilm formation. These findings suggest that this microbial community has the potential to contribute to well souring, biocorrosion, and biofouling within the reservoir. Our research provides unique insights into the early stages of production in one of the most prolific unconventional plays in the United States, with important implications for well management and energy recovery.

natural gas↗
DOE OSTI2018

Investigation of Mixed-Type Craters and the Role of Bifluoride Additives to Produce Zirconia-Toughened Alumina-Based PEO Coating

Al{sub 2}O{sub 3}-ZrO{sub 2} composite ceramic coatings were prepared on Al6061 aluminum alloy by plasma electrolytic oxidation in Na{sub 3}PO{sub 4}-K{sub 2}ZrF{sub 6}-Na{sub 2}SiF{sub 6}-based alkaline electrolyte. Optimum processing time for the coating formation was found to be ~ 50 min. Cross section and surface morphology of the coatings were analyzed using scanning electron microscope. From the phase and elemental composition analysis, the presence of m-ZrO{sub 2} and t-ZrO{sub 2} phases was confirmed. It was further observed that the peak intensities of t-ZrO{sub 2} and α-Al{sub 2}O{sub 3} phases increased with processing time, which was attributed to the enhanced crystallinity caused by the efficient sintering conditions. Corrosion properties were investigated by potentiodynamic polarization test in 3.5 wt.% NaCl solution. The results showed high improvement in corrosion rate with minimum recorded value ~ 0.25 mmy (mm/year) and corrosion current ~ 0.15 × 10{sup −6} A/cm{sup 2}.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Precipitation of Carbides and Dissolution of Widmanstätten Structure for Enhanced Hardness in Ti{sub 2}AlNb-Based Alloys

Carbide-reinforced Ti{sub 2}AlNb matrix composites were spark plasma sintered at 1100 °C by incorporating CNTs into single-B2-phase Ti-22Al-25Nb powders. The as-SPSed alloys were solution treated and then aged in different phase regions. By kinetics analysis and energy-dispersive spectroscopy, it is found carbon will stabilize α{sub 2} phase during solution treatment, and the formation of carbide results in the Nb-depleted regions, which further induces the formation of curly B2 + O Widmanstätten structure during quenching. Different from the general Widmanstätten structure in the aged Ti{sub 2}AlNb alloy, the remained α{sub 2} will consume the B2 within the Widmanstätten structure, when the carbon-added alloy is aged in B2 + O phase region. Compared to the alloy without CNTs, the Vickers hardness of the aged carbon-added Ti{sub 2}AlNb alloy is increased significantly, which is related to the uniform and abundant columnar carbides within the O-phase matrix.

36 MATERIALS SCIENCE↗
NASA NTRS2017

End-to-End Trade-Space Analysis for Designing Constellation

Multipoint measurement missions can provide a significant advancement in science return and this science interest coupled with as many recent technological advances are driving a growing trend in exploring distributed architectures for future NASA missions. Distributed Spacecraft Missions (DSMs) leverage multiple spacecraft to achieve one or more common goals. In particular, a constellation is the most general form of DSM with two or more spacecraft placed into specific orbit(s) for the purpose of serving a common objective (e.g., CYGNSS). Because a DSM architectural trade-space includes both monolithic and distributed design variables, DSM optimization is a large and complex problem with multiple conflicting objectives. Over the last two years, our team has been developing a Trade-space Analysis Tool for Constellations (TAT-C), implemented in common programming languages for pre-Phase A constellation mission analysis. By evaluating alternative mission architectures, TAT-C seeks to minimize cost and maximize performance for pre-defined science goals. This presentation will describe the overall architecture of TAT-C including: a User Interface (UI) at several levels of details and user expertise; Trade-space Search Requests that are created from the Science requirements gathered by the UI and validated by a Knowledge Base; a Knowledge Base to compare the current requests to prior mission concepts to potentially prune the trade-space; a Trade-space Search Iterator which, with inputs from the Knowledge Base, and, in collaboration with the Orbit & Coverage, Reduction & Metrics, and Cost& Risk modules, generates multiple potential architectures and their associated characteristics. TAT-C leverages the use of the Goddard Mission Analysis Tool (GMAT) to compute coverage and ancillary data, modeling orbits to balance accuracy and performance. The current version includes uniform and non-uniform Walker constellations as well as Ad-Hoc and precessing constellations, and its cost model represents an aggregate model consisting of Cost Estimating Relationships (CERs) from widely accepted models. The current GUI automatically generates graphics representing metrics such as average revisit time or coverage as a function of cost. The end-to-end system will be demonstrated as part of the presentation.

Mission Desig↗
NASA NTRS1990

MEASURE: An integrated data-analysis and model identification facility

The first phase of the development of MEASURE, an integrated data analysis and model identification facility is described. The facility takes system activity data as input and produces as output representative behavioral models of the system in near real time. In addition a wide range of statistical characteristics of the measured system are also available. The usage of the system is illustrated on data collected via software instrumentation of a network of SUN workstations at the University of Illinois. Initially, statistical clustering is used to identify high density regions of resource-usage in a given environment. The identified regions form the states for building a state-transition model to evaluate system and program performance in real time. The model is then solved to obtain useful parameters such as the response-time distribution and the mean waiting time in each state. A graphical interface which displays the identified models and their characteristics (with real time updates) was also developed. The results provide an understanding of the resource-usage in the system under various workload conditions. This work is targeted for a testbed of UNIX workstations with the initial phase ported to SUN workstations on the NASA, Ames Research Center Advanced Automation Testbed.

Singh, Jaidip↗
DOE OSTI2022

Cluster Analysis of Combined EDS and EBSD Data to Solve Ambiguous Phase Identifications

A common problem in analytical scanning electron microscopy (SEM) using electron backscatter diffraction (EBSD) is the differentiation of phases with distinct chemistry but the same or very similar crystal structure. X-ray energy dispersive spectroscopy (EDS) is useful to help differentiate these phases of similar crystal structures but different elemental makeups. However, open, automated, and unbiased methods of differentiating phases of similar EBSD responses based on their EDS response are lacking. This paper describes a simple data analytics-based method, using a combination of singular value decomposition and cluster analysis, to merge simultaneously acquired EDS + EBSD information and automatically determine phases from both their crystal and elemental data. I use hexagonal TiB 2 ceramic contaminated with multiple crystallographically ambiguous but chemically distinct cubic phases to illustrate the method. Code, in the form of a Python 3 Jupyter Notebook, and the necessary data to replicate the analysis are provided as Supplementary material.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Numerical and Experimental Analysis of Dissimilar Repair Welding Residual Stress in P91 Steel Considering Solid-State Phase Transformation

Repair welding is a popular method to repair the cracked zones of pipes in power plants. However, residual stresses induced by repair welding are inevitably generated and have a significant effect on the performance of repair-welded components during service. The purpose of this research is to investigate the effects of solid-state phase transformation (SSPT) on the repair welding residual stress distribution of multi-layer and multi-pass welding in P91 steel. Based on thermal elastic-plastic theory, a three-dimensional thermal–metallurgical–mechanical finite element model considering the SSPT is established, and shielded metal arc welding (SMAW) heat input is modelled as one double elliptical heat source. The effect of phase transformation on residual stress is investigated by considering effects with and without phase transformation in the database of materials. The results show that transverse compressive stress and a low longitudinal stress area are generated in the final pass due to martensite transformation. Compared with different zones along the thickness direction, the effect of SSPT is greater around the outer surface than around the internal fusion zone. The rationality of the developed finite element model is verified by the experimental method, and good agreement is obtained between those results from the numerical analysis and experimental methods.

36 MATERIALS SCIENCE↗
NASA NTRS1978

Data analysis of the LPSP experiment on OSO-8

The first and statistically most reliable step in the data analysis - the computation of the vertical phase lag between photospheric and chromospheric oscillations - was completed. Unfortunately, the error associated with this calculated phase lag is so great that the result has no physical significance. Since the subsequent data analysis that was originally planned would have much larger associated errors, it was concluded that the data available is insufficient to allow any meaningful results to be derived. Accordingly, the project was terminated. The reasons for the failure of the data are discussed. There are two basic reasons for this failure; (1) the very low signal to noise ratio of the raw data, and (1) the small statistical sample that resulted from the very small number of usable orbits. The final phase of data analysis is described. Finally, some comments and recommendations of a general nature are made concerning this entire contract effort. It is hoped that at least some lessons can be learned from this particular Guest Investigator project, so that future Guest Investigator programs can be pursued more effectively, and with less risk.

Frazier, E. N.↗
DOE OSTI2018

Phase Transitions in the Antiferromagnetic Heisenberg Model on a Body-Centered Cubic Lattice with Allowance for the Next-Nearest-Neighbor Interactions

Based on the replica exchange Monte Carlo algorithm and histogram analysis of data, the phase transitions in the three-dimensional antiferromagnetic Heisenberg model on a body-centered cubic lattice with allowance for the next-nearest-neighbor interaction are studied. The study is performed for the nextnearest- neighbor exchange interaction ratio of r = 1. It is established that, for this model, the transition from the antiferromagnetic to paramagnetic phase is a first-order phase transition.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1991

Analysis of minerals containing dissolved traces of the fluid phase components water and carbon dioxide

Substantial progress has been made towards a better understanding of the dissolution of common gas/fluid phase components, notably H2O and CO2, in minerals. It has been shown that the dissolution mechanisms are significantly more complex than currently believed. By judiciously combining various solid state analytical techniques, convincing evidence was obtained that traces of dissolved gas/fluid phase components undergo, at least in part, a redox conversion by which they split into reduced H2 and and reduced C on one hand and oxidized oxygen, O(-), on the other. Analysis for 2 and C as well as for any organic molecules which may form during the process of co-segregation are still impeded by the omnipresent danger of extraneous contamination. However, the presence of O(-), an unusual oxidized form of oxygen, has been proven beyond a reasonable doubt. The presence of O(-) testifies to the fact that a redox reaction must have taken place in the solid state involving the dissolved traces of gas/fluid phase components. Detailed information on the techniques used and the results obtained are given.

Freund, Friedemann↗
DOE OSTI2019

Variable Duty Control of Three-Phase Voltage Source Inverter for Wireless Power Transfer Systems

This paper presents duty control and analysis of the three-phase voltage source inverter (VSI) to adjust the output power for three-phase wireless power transfer (WPT) applications. Analytical results show significant reductions in the inverter dc link ripple current with the three-phase system over single-phase WPT counterparts. Simulation and experimental results for an 18 kW three-phase series-series WPT system are included to validate the duty control and analysis. Experimental results also demonstrated the output voltage can be controlled over a wide range by adjusting the inverter duty.

Su, Gui-Jia↗