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.
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This paper describes the use of inverse scattering to calculate the equivalent dielectric constant of a random mixture of two-dimensional scatterers.
Turbulent transport of passive scalars by random wave fields is studied, with applications to statistics of chlorophyll concentration in the ocean.
The effect of random wave fields on passive tracer spatial variations is studied.
This paper describes the test program in detail including test sample description, test procedures, and vibration test results of multiple test samples. The material pairs used in the experiment were Aluminum-Aluminum, Aluminum- Dicronite coated Aluminum, and Aluminum-Plasmadize coated Aluminum. Levels of vibration for each set of twelve samples of each material pairing were gradually increased until all samples experienced substantial displacement. Data was collected on 1) acceleration in all three axes, 2) relative static displacement between vibration runs utilizing photogrammetry techniques, and 3) surface galling and contaminant generation. This data was used to estimate the values of static friction during random vibratory motion when "stick-slip" occurs and compare these to static friction coefficients measured before and after vibration testing.
We use the superposition T-matrix method to compare the far-field scattering matrices generated by spheroidal and spherical volumes of discrete random medium having the same volume and populated by identical spherical particles. Our results fully confirm the robustness of the previously identified coherent and diffuse scattering regimes and associated optical phenomena exhibited by spherical particulate volumes and support their explanation in terms of the interference phenomenon coupled with the order-of-scattering expansion of the far-field Foldy equations. We also show that increasing non-sphericity of particulate volumes causes discernible (albeit less pronounced) optical effects in forward and backscattering directions and explain them in terms of the same interference/multiple-scattering phenomenon.
In this paper we present a full-wave method for determining the effective permittivity for random media in three dimensions. The type of media addresses is composed of spherical dielectric particles in a homogeneous dielectric background.
Dark Current degradation and Dark Current Ran- dom Telegraph Signal after proton irradiation are studied in new scale silicon microvolumes by using a commercial CMOS Image Sensor. Results show that previously reported empirical models describing the Displacement Damage induced degradations are still valid despite the 10 to 100 times smaller depletion volume used. In addition, no evidence of significant Total Ionizing Dose effects is observed. Finally the reduction of the fraction of Random Telegraph Signal (RTS) pixels detected and of the fraction of multi-level RTS pixels is directly linked to the reduction in pixel volume.
This study focuses on displacement damage induced dark current and Random Telegraph Signal (RTS) in STMicroelectronics P-Type photogate, a device moving away from the 4T Pinned-Photodiode, with a sensitive volume exclusively made of boron-doped P-type epitaxy, and collecting holes instead of electrons. Results show a typical trend for the shape of dark current and RTS degradation in CMOS Image Sensors with the exception that the measured generation rates seem 2 times smaller than typical literature values in irradiated silicon. Different hypothesis on the origin of this discrepancy are explored.
Stationarity conditions for a certain periodic random process
Propagation of spherical waves in a weak random medium
Signal stabilization of a control system with random inputs
Non-random oscillation in electroencephalographic alpha blocking response
Analog communication over randomly time varying channels
Hybrid computer determines the probability distributions of instantaneous and peak amplitudes of random signals. This combined digital and analog computer system reduces the errors and delays of manual data analysis.
Random thickness variations in chemically milled aluminum alloy
Structural stability of shells - random pressure excitation and statistical dependence of normal mode response
Random plasma magnetic fields caused by electrons coming closer to plasma atom than mean interelectron distance and by electrons that pass at or beyond this distance