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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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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Building an Adaptive Optics Demonstrator System

Adaptive optics is used to correct the wavefront of a beam of light. It originated in the field of astronomy to correct for atmospheric turbulence. This project was to construct an adaptive optics (AO) system kit from Thorlabs. An AO system consists of three parts: a deformable mirror (DM), a wavefront sensor (WFS), and control software. This system is to be used for future teaching purposes to help others learn about adaptive optics. The AO system came with instruction manuals, which were followed to build and calibrate the system. The instructions included building and aligning the system, how to install and use the software, and how to calibrate deformable mirror. A calibrated system for this project means having the deformable mirror imaged onto the wavefront sensor, with the center of the mirror on the center of the WFS. Also, a flat wavefront, which is achieved by eliminating the tip/tilt of the mirror. Eliminating the tip/tilt reduces the RMS amplitude to a value below 0.200 microns. This causes the wavefront to fold in on itself. We set up a focal plane detector behind beam splitter as a demonstration of what would be seen if this were used with a telescope. The image that should be seen on the focal plane detector is the beam with a diffraction pattern called and Airy Function. The AO system is now ready to be used to teach others about adaptive optics.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2010

Hybrid Decompositional Verification for Discovering Failures in Adaptive Flight Control Systems

Adaptive flight control systems hold tremendous promise for maintaining the safety of a damaged aircraft and its passengers. However, most currently proposed adaptive control methodologies rely on online learning neural networks (OLNNs), which necessarily have the property that the controller is changing during the flight. These changes tend to be highly nonlinear, and difficult or impossible to analyze using standard techniques. In this paper, we approach the problem with a variant of compositional verification. The overall system is broken into components. Undesirable behavior is fed backwards through the system. Components which can be solved using formal methods techniques explicitly for the ranges of safe and unsafe input bounds are treated as white box components. The remaining black box components are analyzed with heuristic techniques that try to predict a range of component inputs that may lead to unsafe behavior. The composition of these component inputs throughout the system leads to overall system test vectors that may elucidate the undesirable behavior

Thompson, Sarah↗
DOE OSTI2017

Turbine system and adapter

A turbine system and adapter are disclosed. The adapter includes a turbine attachment portion having a first geometry arranged to receive a corresponding geometry of a wheelpost of a turbine rotor, and a bucket attachment portion having a second geometry arranged to receive a corresponding geometry of a root portion of a non-metallic turbine bucket. Another adapter includes a turbine attachment portion arranged to receive a plurality of wheelposts of a turbine rotor, and a bucket attachment portion arranged to receive a plurality of non-metallic turbine buckets having single dovetail configuration root portions. The turbine system includes a turbine rotor wheel configured to receive metal buckets, at least one adapter secured to at least one wheelpost on the turbine rotor wheel, and at least one non-metallic bucket secured to the at least one adapter.

42 ENGINEERING↗