Phenomenological field theory
Establishing limited connection between attributes of fundamental field variables and properties of phenomenological fields that represent observed particles
PARTICLE↗
SEARCH · Engineering Papers
Results for “Particle properties”
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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Research on mechanisms of alloy strengthening Semiannual report
Fine oxide particle dispersion strengthened alloy structures and mechanical properties and splat cooling process for alloy development
METAL OXIDE↗
Variations in the interplanetary magnetic field - Mariner 2. I.
Statistical properties of interplanetary magnetic field variations, charged particles propagation in solar system and photospheric processes analyzed, using Mariner II magnetometer
PARTICLE MOTION↗
Space radiation damage to the thermal radiative properties of materials.
Thermal radiative property behavior of materials under elementary charged particle bombardment, determining effect of combined UV plus electron exposure and low energy proton bombardment
THERMAL RADIATION↗
Equilibrium normal-shock and stagnation-point properties of helium for incident-shock Mach numbers from 1 to 30
Charts of thermodynamic properties of helium showing effects of ionization, particle interactions, temperature, and atmospheric pressure
Bengtson, R. D.↗
Interplanetary dust
Physical properties, origin, and evolution of interplanetary dust particles
Bandermann, L. W.↗
Remote sensing of ocean current boundary layer
The author has identified the following significant results. A time series of the Loop Current in the Gulf of Mexico, covering an annual cycle of growth, spreading, and decay, has been obtained in synchronization with ERTS-1. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed either by color or sea state effects associated with the cyclonic boundary. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation. Several spectra of upwelling diffuse light are computed as a function of the concentration of particles and yellow substance. These calculations compare favorably with experimental measurements and show that the ratio of channels method gives ambiguous interpretative results. These results are used to discuss features in images where surface measurements were obtained and are extended to tentative explanation in others.
Maul, G. A.↗
Remote sensing of ocean currents
The author has identified the following significant results. A time series of the Loop Current in the Gulf of Mexico, covering an annual cycle of growth, spreading, and decay, has been obtained in synchronization with ERTS-1. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed either by color or sea state effects associated with the cyclonic boundary. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation. Several spectra of upwelling diffuse light are computed as a function of the concentration of particles and yellow substance. These calculations compare favorably with experimental measurements and show that the ratio of channels method gives ambiguous interpretative results. These results are used to discuss features in images where surface measurements were obtained and are extended to tentative explanation in others.
Maul, G. A.↗
Relationships between ERTS radiances and gradients across ocean fronts
A time series of the Loop Current in the Gulf of Mexico, covering an annual cycle of growth, spreading, and decay, has been obtained in synchronization with ERTS. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed either by color or sea state effects associated with the cyclonic boundary. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation.
Maul, G. A.↗
Space shuttle SRM interim contract, part 2
The characteristics of the solid rocket propellant for use with the space shuttle rocket engine are discussed. Design ramifications have created different web thicknesses and motor operating pressures which have necessitated small changes in the required propellant burning rate at 1,000 psia. However, the SRM burning rate remains well within the range demonstrated in the Poseidon and Minuteman first stage motors. Any change in propellant burning rate can be accomplished readily by a slight modification in the oxidizer particle size distribution. The ballistic and mechanical properties of the propellant remain unchanged from the baseline (Configuration 0).
Source record↗
On the use of the earth resources technology satellite /LANDSAT-1/ in optical oceanography
Observations of the Gulf Stream System in the Gulf of Mexico were obtained in synchronization with LANDSAT-1. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed by color (diffuse radiance) or sea state (specular radiance) effects associated with the cyclonic boundary even in the absence of a surface thermal signature. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation. Several spectra of upwelling diffuse light are computed as a function of the concentration of particles and yellow substance.
Maul, G. A.↗
Evaluation of materials for high performance solar arrays
A program has been underway to evaluate materials for advanced solar arrays which are required to provide power to weight ratios up to 100 W/kg. Severe mission environments together with the lack of knowledge of space environmental materials degradation rates require the generation of irradiation and outgassing engineering data for use in the initial design phase of the flight solar arrays. Therefore, approximately 25 candidate array materials were subjected to selected mission environments of vacuum, UV, and particle irradiation, and their mechanical and/or optical properties were determined where appropriate.
Whitaker, A. F.↗
Infrared emission from grains with fluctuating temperatures
This paper presents a sample calculation of the effects of temperature fluctuations on the far-IR emission by very small grains and on the total radiation emitted by the combination of normal and small grains in interstellar space. The bimodal size distribution of interstellar grains is discussed, steady-state grain temperatures are computed for core-mantle and bare particles, and temperature fluctuations of small bare particles are analyzed. Far-IR emission properties are calculated for spherical core-mantle and bare grains. The results obtained indicate that the use of a fluctuating temperature distribution for small grains shifts the radiation maximum for emission by all grains from about 170 to about 250 microns and that the total IR radiation emitted by small grains is substantially larger than the total emitted by classical-sized grains. It is also found that the temperature ratio between small and classical grains is higher in H II regions than in dark clouds.
Greenberg, J. M.↗
A one-dimensional model describing aerosol formation and evolution in the stratosphere. I - Physical processes and mathematical analogs. II - Sensitivity studies and comparison with observations
A new time-dependent one-dimensional model of the stratospheric sulfate aerosol layer is developed. The model treats atmospheric photochemistry and aerosol physics in detail and includes the interaction between gases and particles explicitly. It is shown that the numerical algorithms used in the model are quite precise. Sensitivity studies and comparison with observations are made. The simulated aerosol physics generates a particle layer with most of the observed properties. The sensitivity of the calculated properties to changes in a large number of aeronomic aerosol parameters is discussed in some detail. The sensitivity analysis reveals areas where the aerosol model is most uncertain. New observations are suggested that might help resolve important questions about the origin of the stratospheric aerosol layer.
Turco, R. P.↗
Theory of deposition of condensible impurities on surfaces immersed in combustion gases
The components resulting from the deposition of inorganic salts (e.g., Na2S04) and oxides present in the combustion products from gas turbine engines were investigated. Emphasis was placed on the effects of multicomponent vapor transport, thermophoretic transport of vapor and small particles to actively cooled surfaces, variable fluid properties within mass transfer boundary layers, and free stream turbulence.
Rosner, D. E.↗
Magnetic space-based field measurements
Because the near Earth magnetic field is a complex combination of fields from outside the Earth of fields from its core and of fields from its crust, measurements from space prove to be the only practical way to obtain timely, global surveys. Due to difficulty in making accurate vector measurements, early satellites such as Sputnik and Vanguard measured only the magnitude survey. The attitude accuracy was 20 arc sec. Both the Earth's core fields and the fields arising from its crust were mapped from satellite data. The standard model of the core consists of a scalar potential represented by a spherical harmonics series. Models of the crustal field are relatively new. Mathematical representation is achieved in localized areas by arrays of dipoles appropriately located in the Earth's crust. Measurements of the Earth's field are used in navigation, to map charged particles in the magnetosphere, to study fluid properties in the Earth's core, to infer conductivity of the upper mantels, and to delineate regional scale geological features.
Langel, R. A.↗
Chemisorption of CO on particulate deposits of platinum
Morphology and CO chemisorption properties are studied as a function of particle size for the case of particulate Pt films, vapor-deposited onto ultrahigh vacuum-cleaved and heat-treated mica surfaces at a 200 C substrate temperature. The particles were found to be mostly irregular in shape and randomly-oriented, with two desorption peaks after CO absorption at 60 C: (1) an alpha peak, at 120 C, attributed to smooth particle surfaces, and (2) a beta peak, at about 175 C, attributed to particle edges and steps. Transmission electron microscopy showed that major changes occur in particle morphology during absorption-desorption cycling, so that the decrease in CO desorption flux may be interpreted as due to particle restructuring, rather than contamination by CO decomposition as in the cases of Ni or Pd on mica. Auger electron spectroscopy corroborates the lack of CO decomposition, even for the case of very small Pt particles.
Doering, D. L.↗
Cyclotron maser radiation from a source structure localized perpendicular to the ambient magnetic field
Particle simulations were used to investigate the properties of electromagnetic radiation produced by the cyclotron maser instability in a source region which is localized in the direction perpendicular to the uniform magnetic field. In the procedure used, the simulation model of Pritchett and Strangeway (1985) for the generation of auroral kilometric radiation (AKR) along an auroral field line was modified to include inhomogeneities perpendicular to the magnetic field. The results are compared with the previous homogeneous simulations with regard to efficiency and saturation mechanism and with expectations based on the feedback model. The implications for the generation and propagation of AKR are discussed.
Pritchett, P. L.↗