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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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Data from: Understanding the biogeochemical and spatial drivers of methane and carbon dioxide fluxes in a large temperate reservoir

This dataset contains spatially resolved measurements of CO₂ and CH₄ fluxes and associated environmental variables collected across 200 sites in Douglas Reservoir (Tennessee, USA) between July 29-August 2, 2024. Measurements include diffusive fluxes of CO₂ and CH₄, CH₄ ebullition, and biogeochemical and spatial variables such as dissolved oxygen, temperature, conductivity, chlorophyll-a, pH, water depth, and distance from the dam. Sampling was conducted using a spatially balanced design to capture longitudinal and depth-related gradients throughout the reservoir. The dataset is structured to support analyses of spatial variability, flux pathway comparisons, and modeling approaches (e.g., spatial statistics and machine learning) aimed at understanding controls on reservoir CO₂ and CH₄ fluxes and improving upscaling to whole-reservoir and regional estimates.

Neeper, Jamie [ORNL] (ORCID:0009000842342101)↗
NASA NTRS1971

New understanding of fiber composite materials

Statistical bounding approach to study of filamentary composites provides understanding of their fracture mechanics. Comparison shows that bounds are in good agreement with data from several fiber-matrix systems, and that they can be used to interpret strength data and provide fracture behavior information leading to improved strength.

Zweben, C.↗
NASA NTRS1972

SEMMS - Understanding the solar electric multimission concept.

The feasibility of developing a solar electric multimission spacecraft (SEMMS) is examined with emphasis on understanding the effect of solar electric propulsion elements on a spacecraft system design. The applicability of Mariner, Viking, and thermoelectric outer planet spacecraft (TOPS) technologies to postulated mission/science objectives is investigated. A Mariner/Viking-based, modular spacecraft evolves which, with minimum modifications, is capable of performing a variety of interplanetary missions, including comet and asteroid rendezvous and orbit of Mercury, Jupiter, and Saturn. An early technology-evaluation flight is recommended to minimize the risk in subsequent missions.

Irace, W. R.↗
NASA NTRS1973

Manned Earth Observatory - Possible contributions towards enhanced understanding of the marine environment

The Manned Earth Observatory (MEO) study being conducted by TRW under the management of NASA/MSFC will establish the conceptual design of and the mission requirements for an Earth Observation Laboratory that will be flown on Shuttle missions beginning in 1980. MEO offers a variety of unique inroads to improving our understanding of the marine environment. The Shuttle-MEO is a valuable addition to a multi-level multi-disciplinary remote sensing program. The unique attributes of MEO are its experimental flexibility due to man-instrument interaction, its complimentary orbit (intermediate between nonorbital and high-orbital platforms), its high weight and volume capacity, and short duration missions.

Gerding, R. B.↗
NASA NTRS1976

Surface studies of barium and barium oxide on tungsten and its application to understanding the mechanism of operation of an impregnated tungsten cathode

Surface studies have been made of multilayer and monolayer films of barium and barium oxide on a tungsten substrate. The purpose of the investigation was to synthesize the surface conditions that exist on an activated impregnated tungsten cathode and obtain a better understanding of the mechanism of operation of such cathodes. The techniques employed in these measurements were Auger spectroscopy and work-function measurements. The results of this study show that the surface of an impregnated cathode is identical to that observed for a synthesized monolayer or partial monolayer of barium on oxidized tungsten by evaluating Auger spectra and work-function measurements. Data obtained from desorption studies of barium monolayers on a tungsten substrate in conjunction with Auger and work-function results have been interpreted to show that throughout most of its life an impreganated cathode has a partial monolayer, rather than a monolayer, of barium on its surface.

Forman, R.↗
NASA NTRS1978

Contribution of remote sensing to understand the Bay as a system

The natural resource management information system concept designed specifically for use with remote sensing is discussed in terms of understanding and studying the Chesapeake Bay as a total system. The Bay is defined as a system comprising the lithosphere, the hydrosphere, and the biosphere, that is the vertical profile encompassed by the systems and a two dimensional plane defining the total watershed of the Bay from the headwaters of its tributaries to a distance in the ocean defined by ten tidal cycles. The Chesapeake Bay system is assumed to be the ecosystem in the largest sense. Ecological partitioning, a methodology resulting from studies of land systems for partitioning the land into geobotanical landscape units, is included along with a breakdown of LANDSAT investigations according to subject area.

Park, A. B.↗
NASA NTRS1980

Distributed problem solving and natural language understanding models

A theory of organization and control for a meaning-based language understanding system is mapped out. In this theory, words, rather than rules, are the units of knowledge, and assume the form of procedural entities which execute as generator-like coroutines. Parsing a sentence in context demands a control environment in wich experts can ask questions of each other, forward hints and suggestions to each other, and suspend. The theory is a cognitive theory of both language representation and parser control.

Rieger, C.↗
NASA NTRS1982

Studies of clusters in the gas phase and application to an understanding of transitions from gaseous to the surface and condensed state

Studies of the structure, stability, electronic properties, and formation kinetics of small clusters were reviewed which provide information useful in furthering understanding of nucleation processes, liquid state properties, and the nature of surfaces. Using mass spectrometric coupled with various high pressure ion clustering and Stark effect-molecular beam techniques, the details of the primary clustering steps leading to the nucleation of bulk liquid from the vapor were and obtained by direct observation results are presented.

Castleman, A. W., Jr.↗
NASA NTRS1982

Understand B-type stars

When observations of B stars made from space are added to observations made from the ground and the total body of observational information is confronted with theoretical expectations about B stars, it is clear that nonthermal phenomena occur in the atmospheres of B stars. The nature of these phenomena and what they imply about the physical state of a B star and how a B star evolves are examined using knowledge of the spectrum of a B star as a key to obtaining an understanding of what a B star is like. Three approaches to modeling stellar structure (atmospheres) are considered, the characteristic properties of a mantle, and B stars and evolution are discussed.

Source record↗
NASA NTRS1983

Understanding the roles of the strategic element cobalt in nickel base superalloys

The United States imports over 90% of its cobalt, chromium, columbium, and tantalum, all key elements in high temperature nickel base superalloys for aircraft gas turbine disks and airfoils. Research progress in understanding the roles of cobalt and some possible substitutes effects on microstructure, mechanical properties, and environmental resistance of turbine alloys is discussed.

Stephens, J. R.↗
NASA NTRS1984

Comprehensive Understanding for Vegetated Scene Radiance Relationships

The improvement of our fundamental understanding of the dynamics of directional scattering properties of vegetation canopies through analysis of field data and model simulation data is discussed. Directional reflectance distributions spanning the entire existance hemisphere were measured in two field studies; one using a Mark III 3-band radiometer and one using rapid scanning bidirectional field instrument called PARABOLA. Surfaces measured included corn, soybeans, bare soils, grass lawn, orchard grass, alfalfa, cotton row crops, plowed field, annual grassland, stipa grass, hard wheat, salt plain shrubland, and irrigated wheat. Some structural and optical measurements were taken. Field data show unique reflectance distributions ranging from bare soil to complete vegetation canopies. Physical mechanisms causing these trends are proposed based on scattering properties of soil and vegetation. Soil exhibited a strong backscattering peak toward the Sun. Complete vegetation exhibited a bowl distribution with the minimum reflectance near nadir. Incomplete vegetation canopies show shifting of the minimum reflectance off of nadir in the forward scattering direction because both the scattering properties or the vegetation and soil are observed.

Kimes, D. S.↗
NASA NTRS1984

Status and Direction of Tribology as a Science in the 80's. Understanding and Prediction

The most challenging research problems in tribology for the next decade or beyond are classified horizontally into two categories: (1) understanding of basic mechanisms and (2) prediction of practical performance. Vertical classifications are in terms of particular themes or fields of interest. Areas where more fundamental work is required are: adhesion and friction of clean and contaminated surfaces; lubrication; new materials; surface characterization at the engineering level (topography) and at the atomic levels (various spectroscopies); and wear.

Tabor, D.↗
NASA NTRS1984

Importance and Definition of Materials in Tribology. Status of Understanding

In general, tribological systems consist of three basic components: the material surfaces in contact, the lubricant, and the environment. The materials in contact and the influence of both bulk and surface properties, indicating the importance of material characterization, on tribological behavior are addressed. Since metals and metallic alloys are the most widely used class of materials in practical devices, attention is focused principally on them. With respect to surface behavior, the effect of contaminants both from within the material and from the environment on adhesive behavior is addressed. The various surface events that alter adhesion, friction, and wear are discussed. These include surface reconstruction, segregation, chemisorption, and compound formation. Examples of these events are presented. Minor nuances in the structure of the outermost layers of solids have a pronounced effect on tribological properties. The importance of characterizing the materials of solids in contact in order to achieve a fundamental understanding of adhesion, friction, and wear and accordingly of methods for their control are addressed.

Buckley, D. H.↗
NASA NTRS1984

Future Directions of Research in Adhesion and Friction. Status of Understanding

Four main classes of materials are covered: metals, ceramics, elastomers and polymers. In dealing with adhesion a distinction is drawn between adhesion (which often involves thermodynamic concepts) and the observed adhesive strength, here designated as the pull-off force. With metals the level of understanding of the interfacial bond is well understood theoretically and was elegantly studied experimentally. However the role of surface roughness and especially ductility needs to be incorporated into an overall view of metallic adhesion. The effect of contaminant films has not gone far beyond purely descriptive language. The friction of metals is understood in terms of surface topography, adhesion and deformation and there are now promising solutions using slipline-field theory. These do not however, cope very satisfactorily with work hardening. For surfaces sliding at higher speeds there are now good models which deal with asperity instabilities produced by frictional heating.

Tabor, D.↗
NASA NTRS1984

EPA Enviropod. A summary of the use of the Enviropod under a Memorandum of Understanding among EPA Region 8, the State of Utah, and the University of Utah Research Institute

Twenty-three missions were flown using the EPA's panoramic camera to obtain color and color infrared photographs of landslide and flood damage in Utah. From the state's point of view, there were many successes. The biggest single obstacle to smooth and continued performance was unavailable aircraft. The Memorandum of Understanding between the State of Utah, the Environmental Protection Agency, and the Center for Remote Sensing and Cartography is included along with forms for planning enviropod missions, for requesting flights, and for obtaining feedback from participating agencies.

Ridd, M. K.↗
NASA NTRS1984

Elastohydrodynamic Lubrication. Status of Understanding

The development of elastohydrodynamic lubrication can be divided into three main stages. The first stage is the development of the idealized form of elastohydrodynamic lubrication, namely where the surfaces are smooth, the fluid behavior is assumed to be Newtonian, and isothermal considerations are assumed. Results based on these assumptions are presented for the complete spectrum of contact geometries (rectangular and elliptical), contact materials (hard and soft), and lubricant availability (fully flooded and starved). The status of understanding for the idealized stage of elastohydrodynamic lubrication is fairly well covered in the existing literature. The second stage of development separately incorporates the effects of a non-Newtonian fluid model, thermal effects, and surface roughness effects into the elastohydrodynamic lubrication model developed in stage 1. Results showing recent developments in this stage are presented. The third stage collectively considers the items considered in stage 2 in investigating the lubrication of real surfaces in their operating environments.

Bernard J Hamrock↗
NASA NTRS1984

Status of Understanding for Bearing Materials

The structural materials and potential failure modes for high technology aircraft gas turbine bearings are reviewed. Among the failure modes discussed for iron-base through-hardened bearing materials are fatigue, surface distress, and corrosion. It is shown that the sub-surface initiated rolling-contact fatigue failure mode is reasonably well understood and in most cases can be controlled by proper material selection and design. Current bearing materials provide long life and high reliability in existing applications. A new generation of materials are being developed which will provide improved fracture toughness, better corrosion resistance, and a further extension of bearing fatigue life. Bearing problems due to surface distress, caused by a variety of surface and near surface anomalies, are less well understood. This area will require the implementation of an interdisciplinary effort to improve the level of understanding of metallic surface-lubricant reactions and interactions.

E N Bamberger↗