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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Device and Method of Scintillating Quantum Dots for Radiation Imaging

A radiation imaging device includes a radiation source and a micro structured detector comprising a material defining a surface that faces the radiation source. The material includes a plurality of discreet cavities having openings in the surface. The detector also includes a plurality of quantum dots disclosed in the cavities. The quantum dots are configured to interact with radiation from the radiation source, and to emit visible photons that indicate the presence of radiation. A digital camera and optics may be used to capture images formed by the detector in response to exposure to radiation.

Burke, Eric R.↗
NASA NTRS2018

NASA Electronic Parts and Packaging (NEPP) Field Programmable Gate Array (FPGA) Single Event Effects (SEE) Test Guideline Update

The following are updated or new subjects added to the FPGA SEE Test Guidelines manual: academic versus mission specific device evaluation, single event latch-up (SEL) test and analysis, SEE response visibility enhancement during radiation testing, mitigation evaluation (embedded and user-implemented), unreliable design and its affects to SEE Data, testing flushable architectures versus non-flushable architectures, intellectual property core (IP Core) test and evaluation (addresses embedded and user-inserted), heavy-ion energy and linear energy transfer (LET) selection, proton versus heavy-ion testing, fault injection, mean fluence to failure analysis, and mission specific system-level single event upset (SEU) response prediction. Most sections within the guidelines manual provide information regarding best practices for test structure and test system development. The scope of this manual addresses academic versus mission specific device evaluation and visibility enhancement in IP Core testing.

Test guidelines↗
NASA NTRS2018

NASA Electronic Parts and Packaging Field Programmable Gate Array Single Event Effects Test Guideline Update

The following are updated or new subjects added to the FPGA SEE Test Guidelines manual: academic versus mission specific device evaluation, single event latch-up (SEL) test and analysis, SEE response visibility enhancement during radiation testing, mitigation evaluation (embedded and user-implemented), unreliable design and its affects to SEE Data, testing flushable architectures versus non-flushable architectures, intellectual property core (IP Core) test and evaluation (addresses embedded and user-inserted), heavy-ion energy and linear energy transfer (LET) selection, proton versus heavy-ion testing, fault injection, mean fluence to failure analysis, and mission specific system-level single event upset (SEU) response prediction. Most sections within the guidelines manual provide information regarding best practices for test structure and test system development. The scope of this manual addresses academic versus mission specific device evaluation and visibility enhancement in IP Core testing.

Field Programmable Gate Array (FPGA)↗
NASA NTRS2002

The Sun's Impact on Climate

We provide an overview of the impact of the Sun on the Earth atmosphere and climate system, focused on heating of Earth's atmosphere and oceans. We emphasize the importance of the spectral measurements of SIM and SOLSTICE- that we must know how solar variations are distributed over ultraviolet, visible, and infrared wavelengths, since these have separate characteristic influences on Earth's ozone layer, clouds, and upper layers of the oceans. Emphasis is also given to understanding both direct and indirect influences of the Sun on the Earth, which involve feedbacks between Earth's stratosphere, troposphere, and oceans, each with unique time scales, dynamics, chemistry, and biology, interacting non-linearly. Especially crucial is the role of all three phases of water on Earth, water vapor being the primary greenhouse gas in the atmosphere, the importance of trace gases such as CO2 arising from their absorption in the "water vapor window" at 800 - 1250/cm (12.5 to 8 microns). Melting of polar ice is one major response to the post-industrial global warming, enhanced due to "ice-albedo" feedback. Finally, water in liquid form has a major influence due to cloud albedo feedback, and also due to the oceans' absorption of solar radiation, particularly at visible wavelengths, through the visible "liquid water window" that allows penetration of visible light deep into the mixed layer, while nearby ultraviolet and infrared wavelengths do not penetrate past the upper centimeter ocean surface skin layer. A large fraction of solar energy absorbed by the oceans goes into the latent heat of evaporation. Thus the solar heating of the atmosphere-ocean system is strongly coupled through the water cycle of evaporation, cloud formation, precipitation, surface runoff and ice formation, to Earth's energy budget and climate, each different climate component responding to variations in different solar spectral bands, at ultraviolet, visible and infrared wavelengths.

Cahalan, Robert↗
NASA NTRS1993

Inference of cirrus cloud properties using satellite-observed visible and infrared radiances. II - Verification of theoretical cirrus radiative properties

The study presents a methodology developed to apply a parameterization of radiative transfer calculations to satellite analyses of cirrus clouds. Cloud heights and optical depths are derived from visible and IR window measurements taken during FIRE when cirrus clouds were present. Geostationary satellite retrievals are compared to lidar-derived cloud heights and retrievals from a polar-orbiting satellite taken at different angles to determine which theoretical models of scattering phase function and single-scattering albedo best represent actual cirrus clouds. Models using small scattering phase function and single-scattering albedo best represent actual cirrus clouds. It is concluded that interpretation of cirrus reflectance with water-droplet models leads to biased results. The cloud-height and optical depth biases can be minimized with the aid of the C20 or cirrostratus models.

Minnis, Patrick↗
NASA NTRS1968

Optical integrating sphere operates at visible and infrared wavelengths

An optical integrating sphere with a faceted reflective lining on the inside surface will provide light randomization /mixing of diffusely and specularly reflected light/ with relatively few reflections. The improved sphere has a sufficiently high reflectivity for both visible and infrared radiation.

Aisenberg, S.↗
NASA NTRS1973

Barium release system

A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time.

Lewis, B. W.↗
NASA NTRS1975

The effect of thin turbulent shear layers on the optical quality of imaging systems

A modified C141 transport was outfitted with a 91.5-cm reflector telescope designed to view objects radiating outside the visible window in the infrared range from 1 micron to 1000 microns. The telescope is situated in a cavity which is operated open port. Spoilers were designed which reduce turbulence-induced excitation of the cavity. The aircraft was designed to operate at altitudes up to 15 km to significantly reduce the effect of the H2O and CO2. Furthermore, the optically degrading influence of the large-scale atmospheric turbulence on land-based telescopes is replaced by the effect of the turbulent shear layer resulting from the spoiler upstream of the cavity. A mathematical model was established to describe the effect of turbulent shear layers on imaging systems and to examine the parameters of interest relevant to potential wind-tunnel experimentation.

Steinmetz, W. J.↗
NASA NTRS1975

Ultraviolet, visible, and infrared rays

Sources of infrared, visible and ultraviolet radiation are discussed, and important associated biological and psychophysiological effects are described. The problem of protection from excessively high or low levels of radiant energy in these spectral regions is considered and optimal levels are suggested.

Taylor, J. H.↗
NASA NTRS1975

The sources of material comprising a mass ejection coronal transient

The origin of the material ejected during a white-light coronal transient on August 26 and 27, 1973, is investigated using simultaneous observations of a slowly ascending prominence and the more rapid accompanying coronal transient. Nearly identical simultaneous images of the prominence were obtained over a six-hour period in the H-alpha and He II (304 A) emission lines; contemporaneous Skylab coronograph observations over approximately 1.5 hours showed that the mass-ejection coronal transient rose above the ascending prominence. Based on analysis of these observations, it is concluded that: (1) the bulk of the ejected material originated in the lower corona, despite the lack of an observed depletion there; (2) the material in the transient was at coronal temperature and was visible in polarized radiation due to Thomson scattering of photospheric light by free electrons; and (3) the total event was far larger, more energetic, and longer lasting than would have been inferred from the prominence observations alone.

Hildner, E.↗
NASA NTRS1977

Electromagnetic scattering and absorption by thin walled dielectric cylinders with application to ice crystals

Important in the atmospheric heat balance are the reflection, transmission, and absorption of visible and infrared radiation by clouds and polluted atmospheres. Integral equations are derived to evaluate the scattering and absorption of electromagnetic radiation from thin cylindrical dielectric shells of arbitrary cross section when irradiated by a plane wave of any polarization incident in a plane perpendicular to the generators. Application of the method to infinitely long hexagonal cylinders has yielded numerical scattering and absorption data which simulate columnar sheath ice crystals. It is found that the numerical procedures are economical for cylinders having perimeters less than approximately fifteen free-space wavelengths.

Senior, T. B. A.↗
NASA NTRS1964

Wedge immersed thermistor bolometers

An immersed thermistor bolometer for the detection of ultraviolet, visible, and infrared radiation is described. Two types of immersed bolometers are discussed. The immersion of thermistor flakes in a lens, or half immersed by optical contact on a lens, is examined. Lens materials are evaluated for optimum immersion including fused aluminum oxide, beryllium oxide, and germanium. The application of the bolometer to instruments in which the entrance pupil of the immersion optics has a high aspect ratio is considered.

Dreyfus, M. G.↗
NASA NTRS1981

Effect of forest canopy closure on incoming solar radiance

In order to better understand the physical processes involved in defoliation assessment from remotely sensed data, a field study was designed to investigate the effect of forest canopy closure and other environmental variables on incoming solar radiation. Diffuse radiation measurements were recorded in red, infrared, and middle infrared wavelengths using the Mark 2 three band field radiometer. Results to date indicate that the percent canopy closure is the single most important variable affecting incoming solar radiation. In the visible and near infrared regions, interaction between time of day and date (defined later as solar zenith angle) also affect radiometric response. Aspect has only limited influence on radiance response. These same variables do not influence middle infrared response, however. Uniformity of the forest canopy appears to be more important. These results are compared to LANDSAT MSS classification results of gypsy moth defoliation.

Dottavio, C. L.↗
NASA NTRS1978

Infrared Astronomical Satellite (IRAS) analysis, introduction

Stray light transmittance analysis on a design of the Infrared Astronomical Satellite (IRAS) is presented. The system was evaluated for scattered radiation propagation with the use of the APART (Arizon's Paraxial Analysis of Radiation Transfer), and the propagation of diffracted energy with both PADE (Paraxial Analysis of Diffracted Energy) and the GUERAP II programs. The scattered radiation analysis was performed by using both a 5% diffuse black on the baffle and vane surfaces and by using a mathematical model of the Martin Black scattering characteristics. The sources of infrared radiation and of radiation in the visible wavelengths are identified. Diffraction effects are dominant only at the large off-axis angles, except for a few specific cases and smaller angles. At the longer wavelengths the diffraction contributions go up significantly. It is the comparative increase which determines which propagation process predominates. Combined transmittance values are presented.

Source record↗
NASA NTRS1986

SAGE observations of stratospheric nitrogen dioxide

The global distribution of nitrogen dioxide in the middle to upper stratosphere (25-45 km altitude) for the period February 1979 to November 1981 has been determined from observations of attenuated solar radiation in the visible region 0.385-0.45 micron by the Stratospheric Aerosol and Gas Experiment (SAGE) satellite instrument. The SAGE-derived NO2 vertical profiles compare well with observations by balloon- and aircraft-borne sensors. The global SAGE NO2 distributions generally show a maximum in mixing ratio of 8 parts per billion by volume at about 35 km altitude near the equatorial latitudes at local sunset. The location of the mixing ratio peak moves synchronously with the overhead sun for the four different seasons. High-latitude NO2 column content shows strong seasonal variation, with a maximum in local summer and a minimum in local winter. Selected data at high-latitude winter seasons are presented, suggesting that the large variation shown could be explained by the coupling of both dynamics and photochemistry of the NO(x) species. Finally, profiles of the ratio of sunset to sunrise NO2 mixing ratios, peaking at about a factor of two at 30 km, are shown.

Chu, W. P.↗
NASA NTRS1986

Infrared observations of the Uranian system

Initial results are presented from analyses of IR interferometer spectrometer data collected by Voyager 2 during passes of Uranus and the moons Miranda and Ariel. The data covered reflected solar radiation in the visible and near-IR and thermal emissions between 25 and 50 microns. An equatorial atmospheric He mole fraction of 0.10-0.20 and a mass fraction of 0.16-0.34 was observed for Uranus. Para-hydrogen was also a significant fraction Uranus CH4 atmosphere. Average polar and equatorial spectra were employed to generate vertical temperature profiles between 60-900 mbar, with the finding that the temperatures at the equator and the poles are markedly similar between 400-900 mbar. The effective temperature of Uranus had a calculated upper limit of about 59.4 K, while the subsolar temperatures of Miranda and Arial were around 86 and 84 K, respectively. The albedos of the two satellites indicated surface microstructures composed of isotopically scattering grains.

Hanel, R.↗