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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Concentrations of trace elements and compounds in the airborne suspended particulate matter in Cleveland, Ohio, from August 1971 to August 1972 and their dependence on wind direction: Complete data listing and concentration roses

Concentrations of 75 chemical constituents in the airborne particulate matter were measured in Cleveland, Ohio during 1971 and 1972. Daily values, maxima, geometric means and their standard deviations covering a 1-year period (45 to 50 sampling days) at each of 16 sites are presented on microfiche for 60 elements, and for a lesser number of days for 10 polycyclic aromatic hydrocarbon compounds (PAH), the aliphatic hydrocarbon compounds (AH) as a group and carbon. In addition, concentration roses showing directional properties are presented for 39 elements, 10 PAH and the AH as a group. The elements (except carbon) are shown both in terms of concentration and percentage of the suspended particulate matter.

King, R. B.↗
NASA NTRS2003

The Study of Biomass Emissions for Defining Radiative Forcing of Climate

Accurate quantification of the amounts of trace gases and particulate matter emitted from vegetation fires and other sources of biomass burning (agricultural waste and biofuels) on a regional and global basis is required by a number of users, including scientists studying a wide range of atmospheric processes, national governments who are required to report greenhouse gas emissions, and those interested in quantifying the sources of air pollution that affect human health at regional scales. Over the past decade, improvements in the ability to detect and map fires using a number of different satellite systems have been achieved, largely through efforts coordinated through working groups organized by the IGBP Data and Information System and Global Observation of Forest Cover (GOFC) projects. In addition, significant advances and improvement in or understanding of the emissions factors for biomass burning in different biomes has resulted through efforts by the Biomass Burning Experiment (BIBEX) organized through the International Global Atmospheric Chemistry project. A number of satellite-based fire data products have been generated, and a number of new products will shortly be available. These new data products will provide the basis for estimating emissions from biomass burning on a global basis. However, a number of issues remain concerning the availability of other data sets needed to generate these estimates. Recognizing these issues, the GOFC-Fire Satellite Validation Workshop (held in Lisbon, Portugal on 9-11 July 2001), recommended that a workshop focusing on Improving Global Estimates of Atmospheric Emissions from Biomass Burning be organized. This workshop was held from 17- 19 July 2002 on the campus of the University of Maryland, College Park, Maryland. This workshop served as the annual meeting of the GOFC/GOLD-Fire Program. The overall goals of the meeting were to review the information products generated from satellite imagery and other sources that are currently available for developing emission estimates from biomass burning, evaluate areas where improved or additional products would be beneficial, and recommend products for use by the atmospheric science community.

Penner, Joyce↗
NASA NTRS1984

Late effects from particulate radiations in primate and rabbit tissues

In connection with studies regarding the hazards posed by ionizing radiations to man in space, the U.S. Air Force conducted an experiment about 20 years ago. In this experiment a large number of young rhesus monkeys was exposed to proton fluxes similar to those to be anticipated during solar flares. After irradiation, the animals were kept at the USAF School of Aerospace Medicine in Texas. The monkeys have been employed in investigations concerning aspects of late radiation damage. These investigations are discussed, taking into account the propagation of fibroblasts from irradiated monkeys. The results of the investigations are evaluated, giving attention also to experiments with white rabbits. It is found that, except in the case of major solar flares, when acute radiation damage could lead quickly to death, the hazards to astronauts from space radiations arise from such debilitating late effects as cataracts, damage to the central nervous system and benign tumors, and life-threatening neoplasia.

Lett, J. T.↗
NASA NTRS1973

Technique for Obtaining Vertical Profiles of Backscattering and Extinction Cross Sections Using Slant Path Lidar Measurements

A method is presented for solving for vertical profiles of atmospheric particulate extinction and backscattering cross-sections utilizing monostatic lidar slant path measurements. The method is an extension of work by Fernald. It is shown that the number of assumptions necessary for an iterative solution of extinction and backscattering cross sections can be reduced if lidar slant path measurements are used to solve directly for optical depths. The technique is useful only if sufficiently accurate lidar measurements are available. With highly accurate measurements it is also possible to solve directly for extinction cross sections without an iterative solution of a transcendental equation if the proper reduction scheme is used. The required accuracy is discussed and results showing the effect of errors are presented.

Spinhirne, J. D.↗
NASA NTRS1978

An estimate of particulates in the vicinity of a Shuttle orbiter due to meteoroid impact

An estimate of the magnitude of released particles in the vicinity of a a Shuttle (STS) Orbiter due to meteoroid impact has been completed. A calculation of the number of particles existing as surface contamination and released by such impacts has been performed. In addition, two estimates of the creation of new particles due to meteoroid cratering (backsplash) have been obtained. In each case, the total number of particles per day as a function of size without regard to velocity, as a function of velocity without regard to size, and as a joint distribution in size and velocity has been calculated.

Barengoltz, J.↗
NASA NTRS1972

Possibilities of observing air pollution from orbital altitudes

Research carried out over a number of years has indicated the feasibility of monitoring global air pollution from orbiting satellites. Optical methods show considerable promise of measuring the burdens of pollution, both gaseous and particulates. Important pollution gases, such as sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone, as well as some hydrocarbon vapors, appear amenable to optical remote sensing. Satellite platforms for carrying out this work would not compete with ground monitoring stations but rather supplement them with a different type of data which could be integrated with ground level measurements to provide an all-embracing picture of pollution buildup, mass migration, and dissipation.

Barringer, A.↗
NASA NTRS2008

Numerically Modeling the Erosion of Lunar Soil by Rocket Exhaust Plumes

In preparation for the Apollo program, Leonard Roberts of the NASA Langley Research Center developed a remarkable analytical theory that predicts the blowing of lunar soil and dust beneath a rocket exhaust plume. Roberts assumed that the erosion rate was determined by the excess shear stress in the gas (the amount of shear stress greater than what causes grains to roll). The acceleration of particles to their final velocity in the gas consumes a portion of the shear stress. The erosion rate continues to increase until the excess shear stress is exactly consumed, thus determining the erosion rate. Roberts calculated the largest and smallest particles that could be eroded based on forces at the particle scale, but the erosion rate equation assumed that only one particle size existed in the soil. He assumed that particle ejection angles were determined entirely by the shape of the terrain, which acts like a ballistic ramp, with the particle aerodynamics being negligible. The predicted erosion rate and the upper limit of particle size appeared to be within an order of magnitude of small-scale terrestrial experiments but could not be tested more quantitatively at the time. The lower limit of particle size and the predictions of ejection angle were not tested. We observed in the Apollo landing videos that the ejection angles of particles streaming out from individual craters were time-varying and correlated to the Lunar Module thrust, thus implying that particle aerodynamics dominate. We modified Roberts theory in two ways. First, we used ad hoc the ejection angles measured in the Apollo landing videos, in lieu of developing a more sophisticated method. Second, we integrated Roberts equations over the lunar-particle size distribution and obtained a compact expression that could be implemented in a numerical code. We also added a material damage model that predicts the number and size of divots which the impinging particles will cause in hardware surrounding the landing rocket. Then, we performed a long-range ballistics analysis for the ejected particulates.

Source record↗
NASA NTRS2012

High Enthalpy Studies of Capsule Heating in an Expansion Tunnel Facility

Measurements were made on an Orion heat shield model to demonstrate the capability of the new LENS-XX expansion tunnel facility to make high quality measurements of heat transfer distributions at flow velocities from 3 km/s (h(sub 0) = 5 MJ/kg) to 8.4 km/s (h(sub 0) = 36 MJ/kg). Thirty-nine heat transfer gauges, including both thin-film and thermocouple instruments, as well as four pressure gauges, and high-speed Schlieren were used to assess the aerothermal environment on the capsule heat shield. Only results from laminar boundary layer runs are reported. A major finding of this test series is that the high enthalpy, low-density flows displayed surface heating behavior that is observed to be consistent with some finite-rate recombination process occurring on the surface of the model. It is too early to speculate on the nature of the mechanism, but the response of the gages on the surface seems generally repeatable and consistent for a range of conditions. This result is an important milestone in developing and proving a capability to make measurements in a ground test environment and extrapolate them to flight for conditions with extreme non-equilibrium effects. Additionally, no significant, isolated stagnation point augmentation ("bump") was observed in the tests in this facility. Cases at higher Reynolds number seemed to show the greatest amount of overall increase in heating on the windward side of the model, which may in part be due to small-scale particulate.

Dufrene, Aaron↗
NASA NTRS2008

Gelation in Aerosols; Non-Mean-Field Aggregation and Kinetics

Nature has many examples of systems of particles suspended in a fluid phase; colloids when in a liquid, aerosols when in a gas. These systems are inherently unstable since if the particles can come together, van der Waals forces will keep them together. In this work we studied the aggregation kinetics of particulate systems, most often aerosols. The emphasis of our work was to study dense systems and systems that gel since previous work had not considered these. Our work obtained a number of significant discoveries and results which are reported here.

Sorensen, C. M.↗
NASA NTRS1974

Variable features on Mars III - Comparison of Mariner 1969 and Mariner 1971 photography

Mariner 9 (M9) and Mariner 6 and 7 photography of common regions of Mars are compared, with appropriate attention to the photometric properties of the camera systems. The comparison provides a 2.5 yr time baseline for study of variable albedo features. We find the development of bright streaks and patches, a phenomenon unobserved through the entire M9 mission; the evolution of dark crater splotches into dark streaks; and a planetwide increase in splotchiness. Yet, a large number of splotches and albedo boundaries remain fixed over the same period. Many of the observations are interpreted in terms of a global fallout and subsequent local redistribution of bright fine particulates raised by global dust storms.

Veverka, J.↗
NASA NTRS1978

Decomposition of N2O over particulate matter

Nitrous oxide is shown to undergo both a thermal and a photochemical decomposition at 296 K when it is adsorbed on various dry sands. The photochemical process occurs with light of wavelengths greater than 280 nm, where gaseous N2O does not absorb. At low pressures (less than 0.1 torr) the half-life for the thermal decomposition of nitrous oxide to nitrogen when placed in contact with about 5 gm of heat-treated Tunisian sand in a one-liter vessel was 350 + or - 35 days. Under certain photolytic conditions this half-life was reduced. The efficiency of the photolytic process for a particular sand depends on the pressure and on the wavelength of light. For Tunisian sand at 1.1 torr and with the full mercury arc, the destruction efficiency is about 0.00002 molecule/incident photon. These results indicate that particulate matter in the troposphere may be responsible for the decomposition of nitrous oxide and hence act as an atmospheric sink for N2O. However, moisture causes a drastic reduction in the number of molecules dissociated per incident photon.

Rebbert, R. E.↗
NASA NTRS1983

Fracto-emission from graphite/epoxy composites

Fracto-emission (FE) is the emission of particles and photons during and following crack propagation. Electrons (EE), positive ions (PIE), and excited and ground state neutrals (NE) were observed. Results of a number of experiments involving principally graphite/epoxy composites and Kevlar single fibers are presented. The physical processes responsible for EE and PIE are discussed as well as FE from fiber- and particulate-reinforced composites.

Dickinson, J. T.↗
NASA NTRS1984

Quantitation of heavy ion damage to the mammalian brain - Some preliminary findings

For several years, studies have been conducted regarding late effects of particulate radiations in mammalian tissues, taking into account the brains of rodents and lagomorphs. Recently, it has become feasible to quantify pathological damage and morpho-physiologic alterations accurately in large numbers of histological specimens. New investigative procedures make use of computer-assisted automated image analysis systems. Details regarding the employed methodology are discussed along with the results of the information. The radiations of high linear energy transfer (LET) cause apparently earlier and more dramatic shrinkage of olfactory glomeruli in exposed rabbit brains than comparable doses of Co-60 gamma photons.

Cox, A. B.↗
NASA NTRS1999

Measurements of Nucleation-Mode Particle Size Distributions in Aircraft Plumes during SULFUR 6

This report summarizes the participation of the University of Denver in an airborne measurement program, SULFUR 6, which was undertaken in late September and early October of 1998 by the Deutsches Zentrum fur Luft und Raumfahrt (DLR). Scientific findings from two papers that have been published or accepted and from one manuscript that is in preparation are presented. The SULFUR 6 experiment was designed to investigate the emissions from subsonic aircraft to constrain calculations of possible atmospheric chemical and climatic effects. The University of Denver effort contributed toward the following SULFUR 6 goals: (1) To investigate the relationship between fuel sulfur content (FSC--mass of sulfur per mass of fuel) and particle number and mass emission index (El--quantity emitted per kg of fuel burned); (2) To provide upper and lower limits for the mass conversion efficiency (nu) of fuel sulfur to gaseous and particulate sulfuric acid; (3) To constrain models of volatile particle nucleation and growth by measuring the particle size distribution between 3 and 100 nm at aircraft plume ages ranging from 10(exp -1) to 10(exp 3) s; (4) To determine microphysical and optical properties and bulk chemical composition of soot particles in aircraft exhaust; and (5) To investigate the differences in particle properties between aircraft plumes in contrail and non-contrail situations. The experiment focused on emissions from the ATTAS research aircraft (a well characterized, but older technology turbojet) and from an in-service Boeing 737-300 aircraft provided by Lufthansa, with modem, high-bypass turbofan engines. Measurements were made from the DLR Dassault Falcon 900 aircraft, a modified business jet. The Atmospheric Effects of Aviation Program (AEAP) provided funding to operate an instrument, the nucleation-mode aerosol size spectrometer (N-MASS), during the SULFUR 6 campaign and to analyze the data. The N-MASS was developed at the University of Denver with the support of NOAA's Office of Global Programs and NASA's AEAP and measures particle size distributions in the 4-100 nm range.

Brock, Charles A.↗
NASA NTRS1983

Absorption of energetic protons by Saturn's Ring G

A reexamination of Pioneer 11 data for the distribution of energetic protons in Saturn's inner magnetosphere has yielded an improved value for the ratio of the cosmic ray albedo neutron decay source strength to the radial diffusion coefficient, and the use of the Blake et al. (1983) lower limit on the source strength is used to find an upper limit on the mean residence time against diffusion. By means of Voyager data on normal optical opacity and radial width, it is found that the particulates in Saturn's Ring G have an efective radius of more than about 0.035 cm, an areal mass density of 1.4 x 10 to the -6th g/sq cm, and an areal number density of 0.008/sq cm. It is reasonably certain that there are no satellites having a radius of the order of 1 km or larger associated with Ring G.

Van Allen, J. A.↗
NASA NTRS1976

Extensive 1-year survey of trace elements and compounds in the airborne suspended particulate matter in Cleveland, Ohio

Concentrations of 75 chemical constituents in the airborne particulate matter were measured in Cleveland, Ohio, during 1971 and 1972. Values covering a 1-year period (45 to 50 sampling days) at each of 16 sites are presented for 60 elements. A lesser number of values is given for sulfate, nitrate, fluoride, acidity, 10 polynuclear aromatic hydrocarbon compounds, and the aliphatic hydrocarbon compounds as a group. Methods used included instrumental neutron activation, emission spectroscopy, gas chromatography, combustion techniques, and colorimetry. Uncertainties in the concentrations associated with the sampling procedures, the analysis methods, the use of several analytical facilities, and samples with concentrations below the detection limits are evaluated in detail. The data is discussed in relation to other studies and source origins. The trace constituent concentrations as a function of wind direction are used to suggest a practical method for air pollution source identification.

King, R. B.↗
NASA NTRS1972

The use of ERTS-1 satellite data in Great Lakes mesometeorological studies

The author has identified the following significant results. In the original proposal, it was hoped that ERTS could, with its extremely high resolution and multispectral capability, detect many meteorological phenomena occurring at the low end of the mesoscale motion spectrum (1 - 100 km). This included convective cloud phenomena, internal wave patterns, air pollution, snow squalls, etc. For meteorologists, ERTS-1 has more than lived up to initial hopes. First-look inspection of images has produced a large number of truly remarkable finds. Some of the most significant are: (1) Images of Lake Ontario during late summer have revealed several extremely good examples of lake breeze frontal cloud patterns. (2) Detection of suspended particulates from Chicago-Gary industrial complex in the 50,000 to 150,000 tons/year category. (3) Inadvertant weather modification due to anthropogenic condensation and ice nuclei from urban areas.

Lyons, W. A.↗
NASA NTRS1973

Comets and the formation of planets

Morphological study of the physical and dynamical processes of planet formation, with emphasis on the role of comet nuclei. A consistent model proposes the formation of comets and planets in preplanetary rings of the residual solar nebula, with subsequent ejection, chiefly by Jupiter, of the comets to Oort's (1950) sphere. Physically, dynamically, or statistically evaluated items include: (1) the total number and mass of comets in Oort's cloud; (2) reevaluation of the diameters and masses of comet nuclei; (3) the processes of nucleation from gravitational and 'Boltzmann' instabilities of gaseous media to agglomerations of particulate matter; and (4) the statistical-dynamical conditions and time scales of orbital interaction of comets with the planets and the consequences of disintegration.

Opik, E. J.↗