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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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Wirelessly Interrogated Position or Displacement Sensors

These sensors could be used in harsh environments. Two simple position or displacement sensors based on inductance- capacitance resonant circuits have been conceived. These sensors are both powered and interrogated without use of wires and without making contact with other objects. Instead, excitation and interrogation are accomplished by means of a magnetic- field- response recorder — an apparatus previously reported in “Magnetic- Field-Response Measurement-Acquisition System” (LAR- 16908), NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. To recapitulate: The magnetic-field-response recorder generates an alternating magnetic field that excites oscillations in the resonant circuit, measures the magnetic response of the circuit, and determines the resonance frequency from the response.

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Inductive Linear-Position Sensor/Limit-Sensor Units

These non-contact devices afford more information than do mechanical limit switches. A new sensor (see figure) provides an absolute position measurement. The figure presents a schematic view of a motorized linear- translation stage that contains, at each end, an electronic unit that functions as both (1) a non-contact sensor that measures the absolute position of the stage and (2) a non-contact equivalent of a limit switch that is tripped when the stage reaches the nominal limit position. The need for such an absolute linear position-sensor/ limit-sensor unit arises in the case of a linear-translation stage that is part of a larger system in which the actual stopping position of the stage (relative to the nominal limit position) must be known. Because inertia inevitably causes the stage to run somewhat past the nominal limit position, tripping of a standard limit switch or other limit sensor does not provide the required indication of the actual stopping position. This innovative sensor unit operates on an electromagnetic-induction principle similar to that of linear variable differential transformers (LVDTs).

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Hilbert-Curve Fractal Antenna With Radiation-Pattern Diversity

Two radiation patterns are attainable without active switching. A printed, folded, Hilbert-curve fractal microwave antenna has been designed and built to offer advantages of compactness and low mass, relative to other antennas designed for the same operating frequencies. The primary feature of the antenna is that it offers the advantage of radiation-pattern diversity without need for electrical or mechanical switching: it can radiate simultaneously in an endfire pattern at a frequency of 2.3 GHz (which is in the S-band) and in a broadside pattern at a frequency of 16.8 GHz (which is in the Kuband). This radiation-pattern diversity could be utilized, for example, in applications in which there were requirements for both S-band ground-to-ground communications and Ku-band ground-to-aircraft or ground-to-spacecraft communications. The lack of switching mechanisms or circuitry makes this antenna more reliable, easier, and less expensive to fabricate than it otherwise would be.

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Single-Camera Panoramic-Imaging Systems

It is not necessary to use multiple cameras covering narrower fields of view. Panoramic detection systems (PDSs) are developmental video monitoring and image-data processing systems that, as their name indicates, acquire panoramic views. More specifically, a PDS acquires images from an approximately cylindrical field of view that surrounds an observation platform. In example of a major class of intended applications, a PDS mounted on top of a motor vehicle could be used to obtain unobstructed views of the surroundings (see Figure 1). In another such example, a PDS could be mounted above a roadway intersection for monitoring approaching and receding vehicles in order to provide image data on the vehicles as input to an automated traffic-control system. In either application, a running archive of the image data acquired by the PDS could be maintained as a means of reconstructing the events leading up to a vehicular collision: used in this way, a PDS would be analogous to an aircraft “black box” data recorder.

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Interface Electronic Circuitry for an Electronic Tongue

Compact, low-noise interface circuits are mounted in proximity to the tongue. Electronic circuitry has been developed to serve as an interface between an electronic tongue and digital input/output boards in a laptop computer that is used to control the tongue and process its readings. Electronic tongues were described in two prior NASA Tech Briefs articles: “Electronic Tongue for Quantitation of Contaminants in Water” (NPO-30601), Vol. 28, No. 2 (February 2004), page 31; and “Electronic Tongue Containing Redox and Conductivity Sensors” (NPO- 30862), Vol. 31, No. 8 (August 2007), page 58. Electronic tongues can be used for a variety of purposes, including evaluating water quality, analyzing biochemicals, analyzing biofilms, and measuring electrical conductivities of soils.

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Inexpensive Clock for Displaying Planetary or Sidereal Time

An external oscillator is substituted for an internal quartz clock oscillator. An inexpensive wall clock has been devised for displaying solar time or sidereal time as it would be perceived on a planet other than the Earth, or for displaying sidereal time on the Earth. The concept of a wall clock synchronized to a period other than the terrestrial mean solar day is not new in itself. What is new here is that the clock is realized through a relatively simple electronic modification of a common battery-powered, quartz-crystal-oscillator- driven wall clock (which, as unmodified, displays terrestrial mean solar time).

Posted in: Briefs, TSP, Electronics & Computers

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Efficient Switching Arrangement for (N + 1)/N Redundancy

This arrangement can be generalized beyond its initial application. An efficient arrangement of four switches has been conceived for coupling, to four output ports, the output powers of any subset of four devices that are members of a redundant set of five devices. In normal operation, the output power of each of four of the devices would be coupled to one of the four output ports. The remaining device would be kept as a spare: normally, its output power would be coupled to a load, wherein that power would be dissipated. In the event of failure of one of the four normally used devices, that device would be disconnected from its output port and connected to the load, and the spare device would be connected to the output from which the failed device was disconnected. Alternatively or in addition, the outputs of one or more devices could be sent to ports other than the ones originally assigned to them.

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