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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 1,459 records · Page 81
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Study of atmospheric and bidirectional effects on surface reflectance and vegetation index time series: Application to NOAA AVHRR and preparation for future space missions

The objectives of the investigation, namely 'to characterize the atmospheric and directional effects on surface reflectance and vegetation index using the First International Satellite Cloud Climatology Project (ISLCSP) Field Experiment (FIFE) data set, develop new algorithms to obtain better Advanced Very High Resolution Radiometer (AVHRR) indices, and define possible improvements for future satellite missions', were addressed in three separate, yet complementary studies. First, it was shown, from theoretical calculations, that visible and near infrared reflectances combined linearly at optimum (one or two) viewing angles relate linearly to the fraction of photosynthetically available radiation absorbed by plants, f(sub par), can be used independently of the type of foliage and substrate, eliminate the effects of sub-pixel spatial heterogeneity, and improve the accuracy of the f(sub par) estimates when compared to the Normalized Difference Vegetation Index, NDVI. Second, it was demonstrated that NDVI, even though it is not a linear combination of radiances or reflectances, can be spatially integrated without significant loss of information from scales of 300 to 1000 m. Third, AVHRR visible and near-infrared reflectances over the FIFE site, separating temporal and bidirectional components and determining the model parameters through an original iterative scheme was successfully modeled. It appears that NDVI generated from the top-of-atmosphere reflectances normalized by the bidirectional effects (as determined in the scheme) is a better vegetation index than maximum NDVI. Details about the three studies are presented.

Frouin, Robert↗
NASA NTRS1992

OSEE responses on D6AC steel due to sample preparation

A cleaning procedure and a contamination method developed at NASA Langley to contaminate sample surfaces with a certain thickness of HD-2 grease are demonstrated. Varying levels of contamination are obtained. Optically stimulated electron emission (OSEE) measurements were performed using the parallel electric field cell and the Pat scan device for clean and contaminated samples with a known amount of common contaminant. The OSEE response is found to be more sensitive for the clean sample than for the contaminated one. It is concluded that the OSEE measurements obtained using these techniques are sensitive to surface conditions and the contaminant thickness variations. It is also shown that the wavelength of illuminating light can have a profound effect on OSEE current levels.

Abedin, M. N.↗
NASA NTRS1992

Preparing EMU for Space Station

An enhanced Extravehicular Mobility Unit (EMU) for the Space Shuttle Program is discussed which is capable of meeting new requirements for SSF support. It is concluded that current SSF documents contain meaningful requirements that should be imposed on the SSF EMU to support SSF assembly and maintenance operations. These requirements fall within three broad areas which encompass revised accommodation aboard Shuttle and SSF, including interior environments; extended operating life resulting from the EVA mission model for SSF assembly and support; and operating safely in Station external environments that differ from those of Shuttle.

Wilde, Richard C.↗
NASA NTRS1993

Microwave digestion preparation and ICP determination of boron in human plasma

A microwave digestion procedure, followed by Inductively Coupled Argon Plasma Spectroscopy, is described for the determination of boron (B) in human plasma. The National Institute of Standards and Technology (NIST) currently does not certify the concentration of B in any substance. The NIST citrus leaves 1572 (CL) Standard Reference Material (SRM) and wheat flour 1567a (WF) were chosen to determine the efficacy of digestion. CL and WF values compare favorably to those obtained from an open-vessel, wet digestion followed by ICP, and by neutron activation and mass spectrometric measurements. Plasma samples were oxidized by doubled-distilled ultrapure HNO3 in 120 mL PFA Teflon vessels. An MDS-81D microwave digestion procedure allows for rapid and relatively precise determination of B in human plasma, while limiting handling hazards and sources of contamination.

Ferrando, A. A.↗
NASA NTRS1927

Technical Preparation of the Airplane "Spirit of St. Louis."

Given here is a brief history of the design and construction of the "Spirit of St. Lewis", the airplane that Charles Lindbergh flew solo across the Atlantic. Although the plan was to modify a standard model Ryan M-2, it was quickly determined that modification was less practical than redesign. Colonel Lindbergh's active participation in the design of the aircraft is noted. Given here are the general dimensions, specifications, weight characteristics, and man hours required to build the aircraft.

Hall, Donald A↗
NASA NTRS1920

Properties and preparation of ceramic insulators for spark plugs

Report describes in detail the preliminary experiments which were made on the conductivity of spark-plug insulators in order to develop a satisfactory comparative method for testing various spark-plug materials. Materials tested were cements, porcelain, feldspar, and quartz.

Silsbee, F B↗
NASA NTRS1993

Process modelling for materials preparation experiments

The main goals of the research consist of the development of mathematical tools and measurement of transport properties necessary for high fidelity modeling of crystal growth from the melt and solution, in particular for the Bridgman-Stockbarger growth of mercury cadmium telluride (MCT) and the solution growth of triglycine sulphate (TGS). Of the tasks described in detail in the original proposal, two remain to be worked on: development of a spectral code for moving boundary problems, and diffusivity measurements on concentrated and supersaturated TGS solutions. During this eighth half-year period, good progress was made on these tasks.

Rosenberger, Franz↗
NASA NTRS1988

Airborne Arctic Stratospheric Expedition Preparation: Ozone

This video shows the rollout of the ER-2 and DC-8 at Ames, takeoffs and landings, and operations aboard the DC-8 and ER-2 in Puntas Arenas, Chile. Animation of the north polar regions showing the ozone hole is also included.

Source record↗