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Non-Destructive Evaluation of Materials via Ultraviolet Spectroscopy

A document discusses the use of ultraviolet spectroscopy and imaging for the non-destructive evaluation of the degree of cure, aging, and other properties of resin-based composite materials. This method can be used in air, and is portable for field use. This method operates in reflectance, absorbance, and luminescence modes.

Posted in: Briefs, TSP

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Low-Impact Mating System for Docking Spacecraft

A document describes a low-impact mating system suitable for both docking (mating of two free-flying spacecraft) and berthing (in which a robot arm in one spacecraft positions an object for mating with either spacecraft). The low-impact mating system is fully androgynous: it mates with a copy of itself, i.e., all spacecraft and other objects to be mated are to be equipped with identical copies of the system. This aspect of the design helps to minimize the number of unique parts and to standardize and facilitate mating operations. The system includes a closed-loop feedback control subsystem that actively accommodates misalignments between mating spacecraft, thereby attenuating spacecraft dynamics and mitigating the need for precise advance positioning of the spacecraft.

Posted in: Briefs, TSP

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Simulation of Stochastic Processes by Coupled ODE-PDE

A document discusses the emergence of randomness in solutions of coupled, fully deterministic ODE-PDE (ordinary differential equations-partial differential equations) due to failure of the Lipschitz condition as a new phenomenon. It is possible to exploit the special properties of ordinary differential equations (represented by an arbitrarily chosen, dynamical system) coupled with the corresponding Liouville equations (used to describe the evolution of initial uncertainties in terms of joint probability distribution) in order to simulate stochastic processes with the proscribed probability distributions. The important advantage of the proposed approach is that the simulation does not require a random-number generator.

Posted in: Briefs, TSP

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Dynamic Stability and Gravitational Balancing of Multiple Extended Bodies

Feasibility of a non-invasive compensation scheme was analyzed for precise positioning of a massive extended body in free fall using gravitational forces influenced by surrounding source masses in close proximity. The N-body problem of classical mechanics is a paradigm used to gain insight into the physics of the equivalent N-body problem subject to control forces.

Posted in: Briefs

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Shaker Fatigue Testing of a Turbine Engine Compressor Blade

Linear dynamic finite-element analysis was used to optimize testing. Hamler Test and Analysis (HTA) provides testing, design, and finite-element analysis (FEA) consulting services, specializing in vibration measurement and experimental vibration analysis tools such as tap testing, modal analysis, operating deflection shapes analysis, and rotating machinery analysis. HTA was contracted to perform physical fatigue testing of a compressor blade from a stationary gas turbine engine used for power generation. Electrodynamic shaker testing was required to verify the client’s analytical vibratory high-cycle fatigue life prediction methodology. The first phase of the shaker testing involved vibrating several blades to failure at the first bending mode, and the second phase involved testing several blades to failure at the first torsion mode.

Posted in: Briefs

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Hyperspectral Sun Photometer for Atmospheric Characterization and Vicarious Calibrations

Data acquired by such devices are used in atmospheric, pollution, and solar energy studies. A hyperspectral sun photometer and associated methods have been developed and demonstrated. Sun photometers are used to measure total (global), direct, and diffuse at-surface solar irradiance. The data acquired by sun photometers are used in atmospheric, pollution, and solar energy studies. In addition, the data acquired by sun photometers are used for radiometric vicarious calibration of optical remote-sensing systems. Sun photometer measurements at various wavelengths can be analyzed to estimate molecular scattering, aerosol extinction, and columnar concentrations of water vapor, ozone, and trace gases in the atmosphere.

Posted in: Briefs

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Dr. David Morrison, Senior Scientist, NASA Astrobiology Institute

NASA Ames Research Center, Moffett Field, CA Dr. David Morrison is senior scientist at the NASA Astrobiology Institute and a founder of the multidisciplinary field of astrobiology. He is an expert on the risk of asteroid impacts and potential ways to mitigate that risk.

Posted in: Who's Who

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