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Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer

Sensitivity to magnetic fields is eliminated. An experimental nuclear-spin gyroscope is based on an alkali-metal/noblegas co-magnetometer, which automatically cancels the effects of magnetic fields. Whereas the performances of prior nuclear-spin gyroscopes are limited by sensitivity to magnetic fields, this gyroscope is insensitive to magnetic fields and to other external perturbations. In addition, relative to prior nuclear-spin gyroscopes, this one exhibits greater sensitivity to rotation. There is commercial interest in development of small, highly sensitive gyroscopes. The present experimental device could be a prototype for development of nuclear-spin gyroscopes suitable for navigation. In comparison with fiberoptic gyroscopes, these gyroscopes would draw less power and would be smaller, lighter, more sensitive, and less costly.

Posted in: Physical Sciences, Briefs, TSP

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Improved Thermal Modulator for Gas Chromatography

Varying temperature can be controlled precisely at relatively low power demand. An improved thermal modulator has been invented for use in a variant of gas chromatography (GC). The variant in question — denoted as two-dimensional gas chromatography (2DGC) or GC-GC — involves the use of three series-connected chromatographic columns, in the form of capillary tubes coated interiorly with suitable stationary phases (compounds for which different analytes exhibit different degrees of affinity). The two end columns are relatively long and are used as standard GC columns. The thermal modulator includes the middle column, which is relatively short and is not used as a standard GC column: instead, its temperature is modulated to affect timed adsorption and desorption of analyte gases between the two end columns in accordance with a 2DGC protocol.

Posted in: Physical Sciences, Briefs

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Four-Point-Latching Microactuator

Fabrication is simplified and susceptibility to jamming greatly reduced. Figure 1 depicts an experimental inchworm- type linear microactuator. This microactuator is a successor to the one described in “MEMS-Based Piezoelectric/ Electrostatic Inchworm Actuator” (NPO- 30672), NASA Tech Briefs, Vol. 27, No. 6 (June 2003), page 68. Both actuators are based on the principle of using a piezoelectric transducer (PZT) operated in alternation with electrostatically actuated clutches to cause a slider to move in small increments. However, the design of the present actuator incorporates several improvements over that of the previous one. The most readily apparent improvement is in geometry and, consequently, in fabrication: In the previous actuator, the inchworm motion was perpendicular to the broad faces of a flat silicon wafer on which the actuator was fabricated, and fabrication involved complex processes to form complex three-dimensional shapes in and on the wafer. In the present actuator, the inchworm motion is parallel to the broad faces of a wafer on which it is fabricated. The components needed to produce the in-plane motion are more nearly planar in character and, consequently, easier to fabricate. Other advantages of the present design are described below.

Posted in: Mechanical Components, Briefs

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Deflection-Compensating Beam for Use Inside a Cylinder

Deflections are minimized by combined effects of the beam and cylinder shapes. A design concept for a beam for a specific application permits variations and options for satisfying competing requirements to minimize certain deflections under load and to minimize the weight of the beam. In the specific application, the beam is required to serve as a motion-controlled structure for supporting a mirror for optical testing in the lower third portion of a horizontal, cylindrical vacuum chamber. The cylindrical shape of the chamber is fortuitous in that it can be (and is) utilized as an essential element of the deflection-minimizing design concept.

Posted in: Mechanical Components, Briefs

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Passive Porous Treatment for Reducing Flap Side-Edge Noise

Advantages include broadband noise reduction with no aerodynamic-lift penalty. A passive porous treatment has been proposed as a means of suppressing noise generated by the airflow around the side edges of partial-span flaps on airplane wings when the flaps are extended in a high-lift configuration. The treatment proposed here does not incur any aerodynamic penalties and could easily be retrofit to existing airplanes. The treatment could also be applied to reduce noise generated by turbomachinery, including wind turbines. Innovative aspects of the proposed treatment include a minimum treatment area and physics-based procedure for treatment design. The efficacy of the treatment was confirmed during wind-tunnel experiments at NASA Ames, wherein the porous treatment was applied to a minute surface area in the vicinity of a flap edge on a 26-percent model of Boeing 777-200 wing.

Posted in: Mechanical Components, Briefs, TSP

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Balanced Flow Meters Without Moving Parts

These meters perturb flows less than their predecessors do. Balanced flow meters are recent additions to an established class of simple, rugged flow meters that contain no moving parts in contact with flow and are based on measurement of pressure drops across objects placed in flow paths. These flow meters are highly accurate, minimally intrusive, easily manufacturable, and reliable. A balanced flow meter can be easily mounted in a flow path by bolting it between conventional pipe flanges. A balanced flow meter can be used to measure the flow of any of a variety of liquids or gases, provided that it has been properly calibrated.

Posted in: Mechanical Components, Briefs

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Bonding by Hydroxide-Catalyzed Hydration and Dehydration

Room-temperature process can be varied to suit optical and non-optical applications. A simple, inexpensive method for bonding solid objects exploits hydroxidecatalyzed hydration and dehydration to form silicatelike networks in thin surface and interfacial layers between the objects. (Silicatelike networks are chemical-bond networks similar to, but looser than, those of bulk silica). The method can be practiced at room temperature or over a wide range of temperatures.

Posted in: Materials, Briefs

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