11,263 research outputs found
The GSFC NASTRAN thermal analyzer new capabilities
An overview of four analysis capabilities, which developed and integrated into the NASTRAN Thermal Analyzer, is given. To broaden the scope of applications, these additions provide the NTA users with the following capabilities: (1) simulating a thermal louver as a means of the passive thermal control, (2) simulating a fluid loop for transporting energy as a means of the active thermal control, (3) condensing a large sized finite element model for an efficient transient thermal analysis, and (4) entering multiple boundary condition sets in a single submission for execution in steady state thermal analyses
Development of an early warning system of crop moisture conditions using passive microwave
Emissivities were calculated from the Nimbus 5 electrically scanning microwave radiometer (ESMR) over 25 km grid cells for the southern Great Plains includin the western two-thirds of Kansas and Oklahoma and northwest Texas. These emissivities, normalized for seasonal temperature changes, were in excellent agreement with theory and measurements made from aircraft and truck sensors at the 1.55 cm wavelength of ESMR. These emissivities were related to crop moisture conditions of the winter wheat in the major wheat producing counties of the three states. High correlations were noted between emissitivity and an antecedent precipitation index (API) used to infer soil moisture for periods when the soils were essentially bare. The emissivities from ESMR were related through API and actual crop condition reports to progress of fall planting, adequacy of crop moisture for stand establishment, and periods of excessive moisture that necessitated replanting. Periods of prolonged frozen soil in the winter were observable at several grid points. The average emissivities of the canopy/soil surface during the maximum canopy development times in the spring showed a good agreement with moisture stress inferred from rainfall and yield data
The Use of Air Photographs in Celtic Field Studies
The Use of Air Photographs in Celtic Field Studies
Regulation of raft architecture
Summary: Raft membrane domains are envisioned as lateral assemblies of cholesterol and sphingolipids which adopt a liquid-ordered membrane phase. Our understanding of the raft architecture in cell membranes is developing rapidly. The current view describes raft domains as small and highly dynamic subdomains of cell membranes. The size and stability of raft domains are essential parameters which determine the function of raft domains in cells. Here we discuss how the architecture and stability of raft domains is regulated by oligomerisation of raft components and by modulation of their molecular compositio
A design study for the incorporation of aeroelastic capability into NASTRAN
Modifications and computational tasks required for aeroelastic capability in NASTRA
Hall current accelerator Final report, 10 Jun. 1964 - 10 Sep. 1965
Axisymmetric Hall current accelerator as electric spacecraft propulsion syste
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Understanding the Role of Small-Scale Flux in Solar Spectral Irradiance Variation
Global solar spectral irradiance variations depend on changes inmagnetic flux concentrations at the smallest scales. Modeling has focused on the contributions of magnetic structures in full disk images as those contributions have strong center-to-limb dependencies, but these dependencies have never been determined radiometrically; only the photometric intensity relative to some reference ’quiet-sun’1, themagnetic structure contrast, is measurable with ground based imagery. This is problematic because unre- solved inhomogeneities influence not only the full-disk structure intensities themselves, but also the quiet-sun background against which their contrast is measured. We thus argue that, to understand the physical causes underlying solar spectral irradiance varia- tions, two fundamental questionsmust be addressed: What is the real Iλ(µ) as a function of B in full-disk images? This can only be answered by imaging the Sun radiometrically from space, and we propose a Radiometric Solar Imager design. What governs spectral irradiance changes at sub arc-second scales? This can be addressed by a combination of high resolution ground based imaging (ATST-VBI) and three dimensional radiative magnetohydrodynamic modeling, and we propose a synoptic approach. Finally, a way to account for the variance introduced by unresolved substructure in spectral irradiance modeling must be devised. This is critical, as imaging and modeling at the highest resolutions but over the full solar disk will likely remain unattainable for some time
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