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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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This paper develops a computational approach to multivariable frequency domain curve fitting, based on 2-norm minimization.
Synthetic Aperture Radar systems provide raw data that need focusing to achieve full-resolution imaging. Current SAR applications, including interferometry, require accurate, phase-preserving, and precisely co-registered coherent images over large ground swaths with the highest achievable resolution. In addition to these challenges, stripmap SAR data may be acquired with an off-broadside (squinted) geometry, either by design or through platform motion. The precise batch focusing of these large aperture and wide bandwidth data sets is known to require a 2D frequency processing approach. The standard wave domain focusing algorithm, however, is only exact for data acquired on a rectilinear trajectory. We investigate a generalization of the standard omega-k focusing formulation that allows curved data acquisition tracks. The new formulation can be used in conjunction with a known extension for conical, squinted imaging grids. The approximations necessary to allow the generalized geometry are analyzed to determine the range of applicability of the proposed algorithm. The theory is validated using data simulated with parameters similar to the UAVSAR L-band SAR system.
We present results from an ongoing program to perform UV measurements (215.0 and 237.0 nm) of the Moon at varying solar phase angles to understand the lunar phase curve at ultraviolet wave- lengths.
We present results from an ongoing program to perform UV measurements of the Moon at varying solar phase angles to understand the lunar phase curve at ultraviolet wavelength.
In FY2020, KSC’s Applied Physics Lab created a computer based image processing system to allow inspection of the new visors being developed for the Artemis Program. This system was based on an ASTM standard where the distortion of an image is used to determine the optical aberrations in a visor, but this approach is restricted to small fields-of-view (small areas of the visor) and is limited in its ability to reliably detect and measure distortion. From our experience with flat surface inspection, we know that other optical techniques can offer higher sensitivity and accuracy. [1] This memorandum describes a method to model and measure the distortion in curved optical surfaces using moir´e interferometry. We were able to apply this process to examine samples of the xEMU Artemis astronaut helmets. Design details are provided along with examples to illustrate performance.
Merchant marine communications forecast curves for august 1962
For flexibility in forming a curved surface, a honeycomb configuration using multiple pleats has proved superior to the usual core structures. The partial pleats formed in individual cell walls permit movements to and from the central axis without tearing.
Relations among potential energy curves of diatomic molecules - quantum mechanics
Photometric study of asteroids - light-curves
Boundary layer thickness on curved walls of 20-in supersonic wind tunnel two-dimensional nozzle
S-curves of electron emission for absorbates, substrates, and arrival rates from partially covered cesium metal surface
Flutter characteristics of curved and flat sandwich panels subjected to supersonic flow
Two-dimensional problem of reconstructing true luminance indicatrix from measured smoothed curve
Longitudinal aerodynamic characteristics of delta wings with curved & straight leading edges from mach 3 to 6
Corpuscular radiation on descending curve of solar activity cycle
Effect of heated concave and convex surfaces of curved tubes on heat transfer behavior of gaseous hydrogen
Measurement of the curved surface finish on gear teeth is made by a device used in conjunction with a conventional profilometer.
Numerical calculation of integrals in Rydberg- Klein-Rees method of potential energy curve calculation