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Compact, Highly Stable Ion Atomic Clock

This high-precision clock is designed for navigation and radio science applications. A mercury-ion clock now at the breadboard stage of development (see figure) has a stability comparable to that of a hydrogen-maser clock: In tests, the clock exhibited an Allan deviation of between 2 × 10–13 and 3 × 10–13 at a measurement time of 1 second, averaging to about 10–15 at 1 day. However, the clock occupies a volume of only about 2 liters — about a hundredth of the volume of a hydrogen- maser clock. The ion- handling parts of the apparatus are housed in a sealed vacuum tube, wherein only a getter pump is used to maintain the vacuum. Hence, this apparatus is a prototype of a generation of small, potentially portable high-precision clocks for diverse ground- and space-based navigation and radio science applications. Furthermore, this new ion-clock technology is about 100 times more stable and precise than the rubidium atomic clocks currently in use in the NAVSTAR GPS Earth-orbiting satellites.

Posted in: Briefs

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System Estimates Radius of Curvature of a Segmented Mirror

A system that estimates the global radius of curvature (GRoC) of a segmented telescope mirror has been developed for use as one of the subsystems of a larger system that exerts precise control over the displacements of the mirror segments. This GRoC-estimating system, when integrated into the overall control system along with a mirror-segment- actuation subsystem and edge sensors (sensors that measure displacements at selected points on the edges of the segments), makes it possible to control the GROC mirror-deformation mode, to which mode contemporary edge sensors are insufficiently sensitive. This system thus makes it possible to control the GRoC of the mirror with sufficient precision to obtain the best possible image quality and/or to impose a required wavefront correction on incoming or outgoing light.

Posted in: Briefs

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Flipperons for Improved Aerodynamic Performance

For a given airfoil design, lift is increased and drag reduced. Lightweight, piezoelectrically actuated bending flight-control surfaces have shown promise as means of actively controlling airflows to improve the performances of transport airplanes. These bending flight-control surfaces are called “flipperons” because they look somewhat like small ailerons, but, unlike ailerons, are operated in an oscillatory mode reminiscent of the actions of biological flippers.

Posted in: Briefs, TSP

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Fabricating High-Resolution X-Ray Collimators

A process and method for fabricating multi-grid, high-resolution rotating modulation collimators for arcsecond and sub-arcsecond x-ray and gamma-ray imaging involves photochemical machining and precision stack lamination. The special fixturing and etching techniques that have been developed are used for the fabrication of multiple high-resolution grids on a single array substrate.

Posted in: Briefs, TSP

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Embossed Teflon AF Laminate Membrane Microfluidic Diaphragm Valves

A new fabrication strategy for valve manifolds uses flexible, durable materials. A microfluidic system has been designed to survive spaceflight and to function autonomously on the Martian surface. It manipulates microscopic quantities of liquid water and performs chemical analyses on these samples to assay for the presence of molecules associated with past or present living processes. This technology lies at the core of the Urey Instrument, which is scheduled for inclusion on the Pasteur Payload of the ESA ExoMars rover mission in 2013.

Posted in: Briefs

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Direct Metal Laser-Sintering of Titanium

DMLS titanium parts can be used in aerospace and medical applications. During the first decade of direct metal laser-sintering (DMLS), the metals employed were generally ones developed specifically for DMLS, rather than those used in traditional metalforming methods. But in recent years, the range of available powder metals and the production quality of DMLS parts have advanced considerably, driving new interest in rapid manufacturing.

Posted in: Manufacturing & Prototyping, Briefs

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Monitoring HIV/AIDS Patients



Posted in: Blog

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