Ground moving target tracking in aerial video presents a difficult algorithmic challenge due to sensor platform motion, non-uniform scene illumination, and other extended operating conditions. Theoretically, trackers which operate on color video should have improved performance vs. monochromatic trackers by leveraging the additional intensity channels. In this work, ground moving targets in color video are characterized in the Hue-Saturation-Value (HSV) color space. Using segmented real aerial video, HSV statistics are measured for multiple vehicle and background types and evaluated for separability and invariance to illumination change, obscuration, and aspect change. HSV statistics are then calculated for moving targets from the same video segmented with existing color tracking algorithms to determine HSV feature robustness to noisy segmentation.
This study extends branch point tolerant phase reconstructor research to examine the effect of finite time delays and measurement error on system performance. Branch point tolerant phase reconstruction is particularly applicable to atmospheric laser weapon and communication systems, which operate in extended turbulence. We examine the relative performance of a least squares reconstructor, least squares plus hidden phase reconstructor, and a Goldstein branch point reconstructor for various correction time-delays and measurement noise scenarios. Performance is evaluated using a wave-optics simulation that models a 100km atmospheric propagation of a point source beacon to a transmit/receive aperture. Phase-only corrections are then calculated using the various reconstructor algorithms and applied to an outgoing uniform field. Point Strehl is used as the performance metric. Results indicate that while time delays and measurement noise reduce the performance of branch point tolerant reconstructors, these reconstructors can still outperform least squares implementations in many cases. We also show that branch point detection becomes the limiting factor in measurement noise corrupted scenarios.
Composite propellers are subject to stringent quality control, extensive developmental testing, and ongoing health assessment. The feasibility of embedded fiber-optic smart instrumentation was examined for use in the commercial manufacture and testing processes used by Hartzell Propeller. Embedded extrinsic Fabry-Perot interferometric (EFPI) fiber-optic strain sensors were used for cure monitoring and material testing of a carbon-graphite plate. Strain was measured during the hot press cure of the four- ply 90/0/0/90 test article. Next, directional strain dependence on temperature and pressure was determined through controlled surveys. Finally, the fiber-optic strain readings were compared to surface resistive strain gage measurements during a tensile test. The cure strain data showed the effects of thermal mismatch between composite, resin, and the press platens. The temperature and pressure surveys validated the use of the sensors over a wide-range of environmental conditions, and the tensile test showed good correlation between embedded and surface strain measurements. Hence, the embedded sensors can provide information on internal strain that was extrapolated form external measurements previously. Experimental implementation of the sensors for cure monitoring and for developmental testing of propellers is ongoing.
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