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Active Aircraft Pylon Noise Control System
Unmanned Aerial Systems Traffic Management
Method of Bonding Dissimilar Materials
Sonar Inspection Robot System
Applying the Dynamic Inertia Measurement Method to Full-Scale Aerospace Vehicles
Method and Apparatus for Measuring Surface Air Pressure
Fully Premixed, Low-Emission, High-Pressure, Multi-Fuel Burner
Self-Healing Wire Insulation
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Allen Parker, Systems Engineer, Advanced Structures and Measurement Group, Dryden Flight Research Center

Allen Parker is a systems engineer with expertise in the areas of fiber optics and data acquisition. He is currently part of the team that is developing and flight testing an innovative new fiber optic wing shape sensor system installed on the Ikhana unmanned aircraft system.

Posted in: Who's Who

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Quantifying Airborne Hydrogen in Nearly Real Time

An indirect method of measuring small concentrations of hydrogen gas in air in nearly real time has been devised to circumvent the difficulty of performing such measurements directly. In this method, a sample of air suspected of containing hydrogen is first enclosed in a suitable container, and its humidity is measured. The enclosed sample is then exposed to ultraviolet light (typically at a wavelength of 254 nm), which photolyzes the hydrogen to water vapor. The exposure time needed for photolysis is of the order of minutes, the exact value depending on the shape and size of the sample container.

Posted in: Briefs, TSP, Materials

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A Technique for Adjusting Eigenfrequencies of WGM Resonators

A simple technique has been devised for making small, permanent changes in the eigenfrequencies (resonance frequencies) of whispering-gallery-mode (WGM) dielectric optical resonators that have high values of the resonance quality factor (Q). The essence of the technique is to coat the resonator with a thin layer of a transparent polymer having an index of refraction close to that of the resonator material.

Posted in: Briefs, TSP, Physical Sciences

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Low-Pressure, Field-Ionizing Mass Spectrometer

This lightweight, low-power instrument functions well in a lowgrade (partial) vacuum. A small mass spectrometer utilizing a miniature field ionization source is now undergoing development. It is designed for use in a variety of applications in which there are requirements for a lightweight, low-power-consumption instrument that can analyze the masses of a wide variety of molecules and ions. The device can operate without need for a high-vacuum, carrier-gas feed radioactive ionizing source, or thermal ionizer. This mass spectrometer can operate either in the natural vacuum of outer space or on Earth at any ambient pressure below 50 torr (below about 6.7 kPa) — a partial vacuum that can easily be reached by use of a small sampling pump. This mass spectrometer also has a large dynamic range — from singly charged small gas ions to deoxyribonucleic acid (DNA) fragments larger than 104 atomic mass units — with sensitivity adequate for detecting some molecules and ions at relative abundances of less than one part per billion.

Posted in: Briefs, TSP, Physical Sciences

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Modifying Operating Cycles To Increase Stability in a LITS

Microwave-interrogation time can be increased while maintaining optimum lamp duty cycle. The short-term instability in the frequency of a linear-ion-trap frequency standard (LITS) can be reduced by modifying two cycles involved in its operation: (1) the bimodal (bright/dim) cycle of a plasma discharge lamp used for state preparation and detection and (2) a microwave-interrogation cycle. The purpose and effect of the modifications is to enable an increase in the microwave-interrogation cycle time, motivated by the general principle that the short-term uncertainty or instability decreases with increasing microwave-interrogation time. Stated from a slightly different perspective, the effect of modifications is to enable the averaged LITS readings to settle to their long-term stability over a shorter total observation time.

Posted in: Briefs, Physical Sciences

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Chamber for Simulating Martian and Terrestrial Environments

Temperature, pressure, and simulated solar radiation can be controlled over wide ranges. An apparatus for simulating the environment at the surface of Mars has been developed. Within the apparatus, the pressure, gas composition, and temperature of the atmosphere; the incident solar visible and ultraviolet (UV) light; and the attenuation of the light by dust in the atmosphere can be simulated accurately for any latitude, season, or obliquity cycle over the entire geological history of Mars. The apparatus also incorporates instrumentation for monitoring chemical reactions in the simulated atmosphere. The apparatus can be used for experiments in astrobiology, geochemistry, aerobiology, and aerochemistry related to envisioned robotic and human exploration of Mars. Moreover, the apparatus can be easily adapted to enable similar experimentation under environmental conditions of (1) the surfaces of moons, asteroids, and comets, and (2) the upper atmospheres of planets other than Mars: in particular, it can be made to simulate conditions anywhere in the terrestrial atmosphere at altitudes up to about 100 km.

Posted in: Briefs, TSP, Physical Sciences

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Algorithm for Detecting a Bright Spot in an Image

Corrections for background intensity and dark current are included. An algorithm processes the pixel intensities of a digitized image to detect and locate a circular bright spot, the approximate size of which is known in advance. The algorithm is used to find images of the Sun in cameras aboard the Mars Exploration Rovers. (The images are used in estimating orientations of the Rovers relative to the direction to the Sun.) The algorithm can also be adapted to tracking of circular shaped bright targets in other diverse applications.

Posted in: Briefs, Information Sciences

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