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Position Sensor Technology for Hydraulic Cylinder Feedback

Variable inductance sensors offer a cost-effective option for mainstream, in-cylinder applications. Alliance Sensors Group, a Division of H.G. Schaevitz LLC, Moorestown, New Jersey Position feedback sensors for hydraulic or pneumatic cylinders have used one of three traditional technologies: magnetostrictive, variable resistance, and variable inductance. As the demand for increased control and functionality has increased, sensor-instrumented cylinders are becoming more important in the heavy industry, subsea, and mobile equipment worlds. Ultimately, a user or systems integrator must determine the requirements of the application and which technology best satisfies it on a total installed cost versus performance basis. The strengths and weaknesses of magnetostrictive, variable resistance, and variable inductance sensors are shown in the figure. These common sensing technologies utilize a long probe that extends into a deep, small-diameter blind hole that has been gun-drilled into the internal end of the cylinder rod.

Posted in: Briefs, Sensors

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Detection of Gases and Vapors Present at Low Concentrations

Ames Research Center, Moffett Field, California A nanostructure-based mechanism was developed for sensing the presence of, and estimating concentration values of, specified chemical components in a sample gas to which the mechanism is exposed, where the concentrations may be as low as five parts per billion. The mechanism receives a sample gas, converts the gas information received to a change in an electrical parameter value (EPV) sensed at each of an array of separately functionalized carbon nanotubes (CNTs), estimates which of a group of specified chemical components is present and the associated chemical concentrations in the sample gas, formats information concerning the chemical components sensed in the sample gas, and transmits this information to selected recipients. The specified chemical components and the corresponding concentration values are displayed on a cellphone screen, a tablet screen, or a computer screen. Optionally, the information is compensated by removing the effects of the presence of ambient gas components that are not of concern in the sample gas.

Posted in: Briefs, Sensors

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Broadband Photon-Counting Microwave Kinetic Inductance Detector

The design has minimal volume of absorptive material, thus yielding a highly sensitive cryogenic detector. Goddard Space Flight Center, Greenbelt, Maryland The planar Microwave Kinetic Inductance Detector (MKID) is very compact and allows a large number of detectors to be fabricated simultaneously and implemented in a focal plane of a telescope using a minimal number of wiring interfaces. In this detector, the incident power is guided through a planar transmission line and absorbed in a thin superconductor with high kinetic inductance. The amount of power absorbed per cubic volume of the detector determines the sensitivity of the detector and its ability to count number of photons. This invention is a detector design that has minimal volume of absorptive material, thus yielding a highly sensitive cryogenic detector. In addition, the design provides a very broad operating frequency range and has low crosstalk among detectors when placed in an array configuration. Using this invention, microwave power can be coupled to an absorptive volume as low as one cubic micron. Furthermore, this design minimizes the amount of trap charges in the detector thus increasing the accuracy in detecting small numbers of photons. The high quality factor of MKID is preserved at its resonance frequency in the microwave frequency band.

Posted in: Briefs, TSP, Sensors

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Micro-LIDAR for Flow Velocimetry

Langley Research Center, Hampton, Virginia A miniature light detection and ranging (LIDAR) velocimetry sensor has been developed to analyze high-velocity and boundary layer flows in real-world conditions. Using Rayleigh scattering, as opposed to the more common particle scattering, the patent-pending sensors provide multiple flow parameters without the need for particle-seeded flows. The compact fiber-optic sensor design can be embedded directly in a test surface, and allows for a variety of near-surface measurement formats enabling real-time, three-component flow velocity mapping, composition, gas density, and temperature data. The versatility of the Micro-LIDAR sensor platform offers broad utility in advanced aerodynamic and fluid dynamic applications requiring boundary-layer, unseeded flow measurements.

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Sensitive, Specific Molecular Detection of Single Bacteria Cells

Marshall Space Flight Center, Alabama A unique amplification chemistry was developed that allows highly specific isothermal detection of bacteria, and presumably eukaryotic cells, at sub-single-cell sensitivities. This is based on the ability to detect rRNA (ribosomal RNA) rather than DNA, as is typical. The difference is that rRNA is present in metabolizing cells at high copy number compared to the cognate DNA coding sequence. This formulation has the additional characteristics of simplified sample preparation, isothermal incubation conditions, and long-term stability in ambient conditions.

Posted in: Briefs, Sensors

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Optical Hotspot Conductive Fluid Flow Sensor

Marshall Space Flight Center, Alabama The Optical Hotspot Flow Sensor (OHFS) enables optical measurement of electrically conductive liquid metal flow rate by exploiting the electrically conductive nature of liquid metals or any other conductive fluid to enable thermal tagging of liquid flow in tubes (US Patent 7,409,875). It is well suited for measuring very low flow rates, on the order of mg/s.

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Low-Cost Backup RPOD System

Lyndon B. Johnson Space Center, Houston, Texas Advanced Optical Systems, Inc. (AOS) developed a low-cost Rendezvous, Proximity Operations, and Docking (RPOD) system that has applications for the future NASA Orion vehicle. Docking operations between the space shuttle and the International Space Station (ISS) required the coordination of real-time sensor data analysis and manual measurements. AOS developed a family of algorithms that processes the centerline docking camera data for navigational information that is currently derived from multiple sensors and manual estimation.

Posted in: Briefs, TSP, Sensors

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