SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Spectral radiance measurements of scale model rocket engine exhaust gases at simulated altitude using high speed scanning spectrometer
Flaw detection by ultrasonic scanning using triangulation methods
Mechanized ultrasonic scanning system for testing butt welds in large aluminum propellant tanks
Applicability of magnetic or integrated circuits to micrometeoroid sensor scanning
Scanning electron microscope for evaluating failure mechanisms in semiconductor devices, and for three-dimensional representation of biological specimens
Fast scan infrared microscope for measuring thermal and electromechanical parameters affecting reliability of microelectronic devices
Fast scan infrared detection and measuring instrument to predict failure of power transistors
Aircraft flight tests of electric scanning microwave radiometer designed for meteorological satellite
Turnstile conical scan feed to improve tracking antenna performance on Apollo-instrumented ships
High resolution mass spectra obtained from fast magnetic scans of gas chromatographic effluents
Complex organic compounds analysis by fast- electrical-scanning high resolution mass spectrometry and gas chromatography
Information processing in brain - cortical excitability cycles, cortical scanning in temporal perception
We present a new spatial acquisition algorithm using subpixel image scanning.
A novel computer simulation methodology to properly characterize the role of probe directivity/pattern compensation in cylindrical near-field scanning geometry is presented.
This paper presents a useful computer simulation methodology to properly characterize the role of probe compensation in cylindrical near-field scanning. The methodology is applied to a linear test array antenna and has been applied to other antenna configurations.
As more and more nonlinear estimation techniques become available, our interest is in finding out what performance improvement, if any, they can provide for practical nonlinear problems that have been traditionally solved using linear methods. In this paper we examine the problem of estimating spacecraft position using conical scan (conscan) for NASA's Deep Space Network antennas. We show that for additive disturbances on antenna power measurement, the problem can be transformed into a linear one, and we present a general solution to this problem, with the least square solution reported in literature as a special case. We also show that for additive disturbances on antenna position, the problem is a truly nonlinear one, and we present two approximate solutions based on linearization and Unscented Transformation respectively, and one 'exact' solution based on Markov Chain Monte Carlo (MCMC) method. Simulations show that, with the amount of data collected in practice, linear methods perform almost the same as MCMC methods. It is only when we artificially reduce the amount of collected data and increase the level of noise that nonlinear methods show significantly better accuracy than that achieved by linear methods, at the expense of more computation.
The Problem -- Model NASA?s Space Communication and Navigation (SCaN) Integrated Network Architecture (INA) to perform System of Systems & Trade Space architecture evaluation.
This poster introduces a feeding concept aimed at simplifying the backend (phase shifters) of traditional phased arrays. As an alternative to traditional phased arrays, we employ a traveling wave array (TWA) using a single feedline whose propagation constant is controlled via a single, small mechanical movement without a need for phase shifters to enable scanning. Specifically, a dielectric plunger is positioned within a parallel plate waveguide (PPW) transmission line (TL) that feeds the TWA. By adjusting the position of the dielectric plunger within the PPW feeding the TWA, beam steering is achieved. A 20-element array is designed at 13 gigaherz shown to give stable realized gain across the angular range of minus 25 degrees less than or equal to theta and less than or equal to 25 degrees. A proof of concept array is fabricated and measured to demonstrate and validate the concept's operation.