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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Simplified and refined finite element approaches for determining stresses and internal forces in geometrically nonlinear structural analysis

Two methods for determining stresses and internal forces in geometrically nonlinear structural analysis are presented. The simplified approach uses the mid-deformed structural position to evaluate strains when rigid body rotation is present. The important feature of this approach is that it can easily be used with a general-purpose finite-element computer program. The refined approach uses element intrinsic or corotational coordinates and a geometric transformation to determine element strains from joint displacements. Results are presented which demonstrate the capabilities of these potentially useful approaches for geometrically nonlinear structural analysis.

Robinson, J. C.↗
DOE OSTI2026

Raman spectroscopic investigation of ianthinite [U$_2^{4+}$(UO$_2$)$_4$O$_6$(OH)$_4$(H$_2$O)$_4$]·$5$H$_2$O, a rare mixed-valence uranium oxide hydrate

Ianthinite ([[U$_2^{4+}$(UO$_2$)$_4$O$_6$(OH)$_4$(H$_2$O)$_4$]·$5$H$_2$O) is an exotic mineral that possesses U in both tetravalent and hexavalent oxidation states and is structurally related to the U 3 O 8 polymorphs, which are commonly encountered technogenic materials in the nuclear fuel cycle. Despite the similarities between U 3 O 8 and ianthinite, and the importance of ianthinite in U paragenesis, no Raman spectra have been reported for this mineral. Here, to gain a more complete understanding of how structural attributes of ianthinite give rise to observable spectroscopic features and how these may relate to important materials in the nuclear fuel cycle, we provide, for the first time, Raman spectra of ianthinite. Ianthinite readily oxidizes at ambient conditions, complicating analysis of phase-pure material. Several analytical methods are employed herein to decouple the Raman features of ianthinite from its alteration product(s). First, a simple difference spectrum is presented, then results of Raman spectroscopic mapping are employed, and finally, we use a novel processing and analysis method. Each analysis method provides different insight into structural features that are unique to ianthinite, in particular, features that are attributable to U(IV) in distorted octahedral coordination in both ianthinite and U 3 O 8 phases.

Spano, Tyler L. [Oak Ridge National Laboratory (OR↗
NASA NTRS2011

Pattern Recognition for a Flight Dynamics Monte Carlo Simulation

The design, analysis, and verification and validation of a spacecraft relies heavily on Monte Carlo simulations. Modern computational techniques are able to generate large amounts of Monte Carlo data but flight dynamics engineers lack the time and resources to analyze it all. The growing amounts of data combined with the diminished available time of engineers motivates the need to automate the analysis process. Pattern recognition algorithms are an innovative way of analyzing flight dynamics data efficiently. They can search large data sets for specific patterns and highlight critical variables so analysts can focus their analysis efforts. This work combines a few tractable pattern recognition algorithms with basic flight dynamics concepts to build a practical analysis tool for Monte Carlo simulations. Current results show that this tool can quickly and automatically identify individual design parameters, and most importantly, specific combinations of parameters that should be avoided in order to prevent specific system failures. The current version uses a kernel density estimation algorithm and a sequential feature selection algorithm combined with a k-nearest neighbor classifier to find and rank important design parameters. This provides an increased level of confidence in the analysis and saves a significant amount of time.

Restrepo, Carolina↗
NASA NTRS1982

Recent developments in thermal radiation system analyzer (Trasys)

Changes in the thermal radiation analyzer system (TRASYS) computer program are discussed. New capabilities were added while keeping intact the same data input structure. An overview of the program structure and general capabilities is given. Where appropriate, assessments are made of new features. The application of TRASYS peripheral programs and the importance they have in developing a totally integrated thermal analysis system are discussed. Form factor computations times were reduced approximately 40 percent, and the longer flux runs were reduced 50 percent when shadow tables were used.

Vogt, R. A.↗
NASA NTRS1981

Exploration for fractured petroleum reservoirs using radar/Landsat merge combinations

Since fractures are commonly propagated upward and reflected at the earth's surface as subtle linears, detection of these surface features is extremely important in many phases of petroleum exploration and development. To document the usefulness of microwave analysis for petroleum exploration, the Arkansas part of the Arkoma basin is selected as a prime test site. The research plan involves comparing the aircraft microwave imagery and Landsat imagery in an area where significant subsurface borehole geophysical data are available. In the northern Arkoma basin, a positive correlation between the number of linears in a given area and production from cherty carbonate strata is found. In the southern part of the basin, little relationship is discernible between surface structure and gas production, and no correlation is found between gas productivity and linear proximity or linear density as determined from remote sensor data.

Macdonald, H.↗
NASA NTRS2021

Empirical Constraints on Progressive Shock Metamorphism of Magnetite from the Siljan Impact Structure, Sweden

Little is known about the microstructural behavior of magnetite during hypervelocity impact events, even though it is a widespread accessory mineral and important magnetic carrier in terrestrial and extraterrestrial rocks. We report systematic electron backscatter diffraction crystallographic analysis of shock features in magnetite, from a transect across the 52-km diameter ~380 Ma Siljan impact structure in Sweden. Magnetite grains in granitoid samples contain brittle fracturing, crystal-plasticity, and lamellar twins. Deformation twins along {111} with shear direction of <112> are consistent with spinel-law twins. Inferred bulk shock pressures for investigated samples, as constrained by planar deformation features (PDFs) in quartz and shock twins in zircon, range from 0–20 GPa; onset of shock-induced twinning in magnetite is observed at >5 GPa. These results highlight the utility of magnetite to record shock deformation in rocks that experience shock pressures >5 GPa, which may be useful in quartz-poor samples. Despite significant hydrothermal alteration, and variable transformation of host magnetite to hematite, shock effects are preserved, demonstrating that magnetite is a reliable mineral for preserving shock deformation over geologic time.

magnetite↗
NASA NTRS2023

Seasonality of the Migrating Semidiurnal Tide in the Tropical Upper Mesosphere and Lower Thermosphere and its Thermodynamic and Momentum Budget

This work uses the Specified Dynamics-Whole Atmosphere Community Climate Model with Ionosphere/Thermosphere eXtension (SD-WACCM-X) to determine and explain the seasonality of the migrating semidiurnal tide (SW2) components of tropical upper mesosphere and lower thermosphere (UMLT) temperature, zonal wind, and meridional wind. This work also quantifies aliasing due to SW2 in satellite-based tidal estimates. Results show that during equinox seasons, the vertical profiles of tropical UMLT temperature SW2 and zonal-wind SW2’s amplitudes have a double-peak structure while they, along with meridional-wind SW2, have a single-peak structure in their amplitudes in June solstice. Hough mode reconstruction reveals that a linear combination of five SW2 Hough modes cannot fully reproduce these features. Tendency analysis reveals that for temperature, the adiabatic term, nonlinear advection term, and linear advection term are important. For the winds, the classical terms, nonlinear advection term, linear advection term, and gravity wave drag are important. Results of our alias analysis then indicate that SW2 can induce an ∼60% alias in zonal-mean and DW1 components calculated from sampling like that of the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics satellite and the Aura satellite. This work concludes that in situ generation by wave–wave interaction and/or by gravity waves plays significant roles in the seasonality of tropical UMLT temperature SW2, zonal-wind SW2, and meridional-wind SW2. The alias analysis further adds that one cannot simply assume that SW2 in the tropical UMLT is negligible.

Tides↗
NASA NTRS2003

Guide for Hydrogen Hazards Analysis on Components and Systems

The physical and combustion properties of hydrogen give rise to hazards that must be considered when designing and operating a hydrogen system. One of the major concerns in the use of hydrogen is that of fire or detonation because of hydrogen's wide flammability range, low ignition energy, and flame speed. Other concerns include the contact and interaction of hydrogen with materials, such as the hydrogen embrittlement of materials and the formation of hydrogen hydrides. The low temperature of liquid and slush hydrogen bring other concerns related to material compatibility and pressure control; this is especially important when dissimilar, adjoining materials are involved. The potential hazards arising from these properties and design features necessitate a proper hydrogen hazards analysis before introducing a material, component, or system into hydrogen service. The objective of this guide is to describe the NASA Johnson Space Center White Sands Test Facility hydrogen hazards analysis method that should be performed before hydrogen is used in components and/or systems. The method is consistent with standard practices for analyzing hazards. It is recommended that this analysis be made before implementing a hydrogen component qualification procedure. A hydrogen hazards analysis is a useful tool for hydrogen-system designers, system and safety engineers, and facility managers. A hydrogen hazards analysis can identify problem areas before hydrogen is introduced into a system-preventing damage to hardware, delay or loss of mission or objective, and possible injury or loss of life.

Beeson, Harold↗
NASA NTRS1991

Data acquisition and analysis on a Macintosh

The introduction of inexpensive analog-to-digital boards for the Macintosh opens the way for its use in areas that have previously been filled by either specialized, dedicated or more expensive mainframe based systems. Two such Macintosh-based systems are the Acoustic Laboratory Data Acquisition System (ALDAS) and the Jet Calibration and Hover Test Facility (JCAHT) data acquisition system. ALDAS provides an inexpensive, transportable means to digitize four channels at up to 50,000 samples per second and analyze this data. The ALDAS software package was written for use with rotorcraft acoustics and performs automatic acoustic calibration of channels, data display, and various types of data analysis. The program can use data obtained either from internal analog-to-digital conversion or discrete external data imported in ASCII format. All aspects of ALDAS can be improved as new hardware becomes available and new features are introduced into the code. The JCAHT data acquisition system was built as not only an analysis program but also to act as the online safety monitoring system. This paper will provide an overview of these systems.

Watts, Michael E.↗
NASA NTRS2004

Ion Flux Environments for Exposed Spacecraft Surfaces in Interplanetary Space

Spacecraft surfaces in interplanetary space are exposed to solar wind ions. The bulk of the ions exhibit energies of a few kilovolts and are important only to surface interactions while a fraction of the solar wind extends to greater energies and may penetrate below the material surface. The importance of including solar wind ions in analysis of space environment effects on spacecraft is becoming more important as new spacecraft designs are considered which include systems such as sunshades, solar sail propulsion systems, and other mission critical features based on very thin materials. This paper provides a status report on development of solar wind ion environments to support engineering analysis of materials exposed to the space environment including techniques for reconstructing ion environments from solar wind plasma moments and energetic flux measurements and comparison of statistical flux environments to integrated mission fluence.

Minow, Joseph I.↗
DOE OSTI2025

Machine Learning in the Context of Laser-Induced Breakdown Spectroscopy

The integration of machine learning (ML) with Laser-Induced Breakdown Spectroscopy (LIBS) has revolutionized the analytical capabilities of LIBS. The combi-nation of both methods enables more accurate and efficient data analysis. While LIBS itself is a powerful technique for elemental analysis, the vast amount of spectral data it generates can be hard to interpret. Machine learning addresses these challenges by leveraging algorithms that can learn from data, identify patterns, and make predictions without explicit programming for the interpretation of each specific task. In LIBS application, ML techniques are used to enhance various analytical processes. For example, ML algorithms can classify materials based on their spectral fingerprints, predict the concentration of elements in a sample, and identify underlying patterns within complex datasets. Here, this application improves the precision of LIBS analyses while significantly reducing the time required for data processing and interpretation. In this chapter, the fundamental concepts of ML will be discussed first. Following this, the process of data splitting and the importance of feature selection will be examined. Several machine learning methods will then be closely examined, exploring how each can benefit LIBS analysis and highlighting their respective advantages and shortcomings. This structured approach will provide a comprehensive understanding of the integration of ML in the context of LIBS analysis.

47 OTHER INSTRUMENTATION↗
NASA NTRS1977

A study of Stormsat interactive data analysis facility

Stormsat, a third generation geosynchronous satellite intended for the investigation and forecasting of severe local storms, tropical cyclones and other mesoscale phenomena, could be launched as early as 1982. The paper outlines the interactive data processing and analysis functions which must be performed and presents a possible configuration capable of achieving the demonstration forecast objectives. Important features of the data processing system include (1) interactive extraction of wind, temperature and moisture profiles, cloud structure and precipitation from Stormsat data, and (2) numerical and statistical modeling necessary to provide demonstration forecasts.

Hasler, A. F.↗
NASA NTRS1979

The gate studies: Assessing the potential of future small general aviation turbine engines

Four studies were completed that explore the opportunities for future General Aviation turbine engines (GATE) in the 150-1000 SHP class. These studies forecasted the potential impact of advanced technology turbine engines in the post-1988 market, identified important aircraft and missions, desirable engine sizes, engine performance, and cost goals. Parametric evaluations of various engine cycles, configurations, design features, and advanced technology elements defined baseline conceptual engines for each of the important missions identified by the market analysis. Both fixed-wing and helicopter aircraft, and turboshaft, turboprop, and turbofan engines were considered. Sizable performance gains (e.g., 20% SFC decrease), and large engine cost reductions of sufficient magnitude to challenge the reciprocating engine in the 300-500 SHP class were predicted.

Strack, W. C.↗
NASA NTRS1979

New opportunities for future small civil turbine engines: Overviewing the GATE studies

An overview of four independent studies forecasts the potential impact of advanced technology turbine engines in the post 1988 market, identifies important aircraft and missions, desirable engine sizes, engine performance, and cost goals. Parametric evaluations of various engine cycles, configurations, design features, and advanced technology elements defined baseline conceptual engines for each of the important missions identified by the market analysis. Both fixed-wing and helicopter aircraft, and turboshaft, turboprop, and turbofan engines were considered. Sizable performance gains (e.g., 20% SFC decrease), and large engine cost reductions of sufficient magnitude are predicted to challenge the reciprocating engine in the 300-500 SHP class.

Strack, W. C.↗
NASA NTRS1979

The GATE studies - Assessing the potential of future small general aviation turbine engines

Four studies have been completed that explore the opportunities for future General Aviation Turbine Engines (GATE) in the 150-1000 SHP class. These studies forecasted the potential impact of advanced technology turbine engines in the post-1988 market, identified important aircraft and missions, desirable engine sizes, engine performance and cost goals. Parametric evaluations of various engine cycles, configurations, design features, and advanced technology elements defined baseline conceptual engines for each of the important missions identified by the market analysis. Both fixed-wing and helicopter aircraft, and turboshaft, turboprop, and turbofan engines were considered. Key technology areas were recommended for NASA support in order to realize proposed improvements.

Strack, W. C.↗
NASA NTRS1979

New opportunities for future small civil turbine engines - Overviewing the GATE studies

This paper presents an overview of four independent studies that explore the opportunities for future General Aviation Turbine Engines (GATE) in the 150-1000 SHP class. Detroit Diesel Allison, Garrett/AiResearch, Teledyne CAE, and Williams Research participated along with several airframers. These studies forecasted the potential impact of advanced technology turbine engines in the post-1988 market, identified important aircraft and missions, desirable engine sizes, engine performance and cost goals. Parametric evaluations of various engine cycles, configurations, design features, and advanced technology elements defined baseline conceptual engines for each of the important missions identified by the market analysis. Both fixed-wing and helicopter aircraft, and turboshaft, turboprop, and turbofan engines were considered. All four companies predicted sizable performance gains (e.g., 20% SFC decrease), and three predicted large engine cost reductions of sufficient magnitude to challenge the reciprocating engine in the 300-500 SHP class. Key technology areas were recommended for NASA support in order to realize these improvements.

Strack, W. C.↗
NASA NTRS2005

Surface Clutter Removal in Airborne Radar Sounding Data from the Dry Valleys, Antarctica

We have collected roughly 1,000 line-km of airborne radar sounding data over glaciers, rock/ice glaciers, permafrost, subsurface ice bodies, ice-covered saline lakes, and glacial deposits in Taylor and Beacon Valley. These data are being analyzed in order to develop techniques for discriminating between subsurface and off-nadir echoes and for detecting and characterizing subsurface interfaces. The identification of features on Mars exhibiting morphologies consistent with ice/rock mixtures, near-surface ice bodies and near-surface liquid water, and the importance of such features to the search for water on Mars, highlights the need for appropriate terrestrial analogs and analysis techniques in order to prepare for radar sounder missions to Mars. Climatic, hydrological, and geological conditions in the Dry Valleys of Antarctica are analogous in many ways to those on Mars. A crucial first step in the data analysis process is the discrimination of echo sources in the radar data. The goal is to identify all returns from the surface of off-nadir topography in order to positively identify subsurface echoes. This process will also be critical for radar data that will be collected in areas of Mars exhibiting significant topography, so that subsurface echoes are identified unambiguously. The positive detection and characterization of subsurface (including sub-ice) water is a primary goal of NASA's Mars exploration program. Our data over the Dry Valleys provides an opportunity to implement techniques we are developing to accomplish these goals.

Holt, J. W.↗
NASA NTRS1992

SRMAFTE facility checkout model flow field analysis

The Solid Rocket Motor Air Flow Equipment (SRMAFTE) facility was constructed for the purpose of evaluating the internal propellant, insulation, and nozzle configurations of solid propellant rocket motor designs. This makes the characterization of the facility internal flow field very important in assuring that no facility induced flow field features exist which would corrupt the model related measurements. In order to verify the design and operation of the facility, a three-dimensional computational flow field analysis was performed on the facility checkout model setup. The checkout model measurement data, one-dimensional and three-dimensional estimates were compared, and the design and proper operation of the facility was verified. The proper operation of the metering nozzles, adapter chamber transition, model nozzle, and diffuser were verified. The one-dimensional and three-dimensional flow field estimates along with the available measurement data are compared.

Dill, Richard A.↗