Abstract: A device operative to detect metal objects. The device includes a transmitter circuit, an upper transmitter coil and a lower transmitter coil operatively connected to the transmitter circuit. A current fed through the upper transmitter coil and the lower transmitter coil generates a field that excites eddy currents in metal objects in the vicinity of the upper transmitter coil and the lower transmitter coil. An upper magnetic field detector and a lower magnetic field detector are operative to sense eddy currents generated in the metal objects. Processor elements operatively connected to the upper magnetic field detector and the lower magnetic field detector collect, store and analyze the eddy currents and thereby determine the likelihood that a metal object has been detected. A navigation system operatively connected to the processor elements controls movement of the device.

Abstract: An expandable sensor array including at least one expandable member movable between an unexpanded stowed state and an expanded deployed state and a plurality of sensors interconnected with the at least one inflatable member and operatively connected to form a sensor array.

Abstract: A multi-functional sensor system for simultaneously monitoring various parameters such as the structural, chemical and environmental conditions associated with a medium to be monitored, e.g., bridges, high-rise buildings, pollution zones, is provided wherein the system includes at least a plurality of wireless multi-functional sensor platforms embedded in the medium in which an interrogation unit transmits power and receives responses. Each wireless multi-functional sensor platform includes multiple channels for accommodating a plurality of sensor types to simultaneously monitor the parameters associated with the medium. Thus, the wireless sensor platforms are formed to include those sensor types which are considered germane to the intended medium to be monitored.

Abstract: A wind tunnel model design employs a reinforcing strongback 10, made of a rigid material, for receiving a balance 12. At least one jacket section 14, made of a rapid prototype (RP) material, fits over the strongback 10 and defines at least part of an aerodynamic surface. Other aerodynamic surfaces, made of either RP materials or conventional metal materials, may be attached directly to the strongback 10.

Abstract: An instrumented torso model that simulates anatomical features and measures the effects on a body caused by various types of impacts. Simulated bone having material properties similar to that of healthy human bone is surrounded by simulated tissue. At least one sensor array is attached to either or both of the simulated bone and the simulated tissue for measuring the effects of the impacts.

Abstract: A harmonic radar nonlinear junction detector system for detecting concealed weapons, electronics, and other man-made objects utilizing state-of-the art wireless technology, circuit fabrication, signal synthesis, and computer processing techniques to detect and characterize man-made objects possessing nonlinear junctions. The system transmits a pair of low power waveforms and a receiver within the system is coherently tuned to harmonics of the transmitted frequencies of the waveforms to detect man-made metal objects and electronics that contain non-linear junctions. The receiver is also capable of receiving inter-modulation products reflected from the man-made objects that are a result of using two incident signals. The system uses two signal sources generating user-definable waveforms of variable frequencies in order to provide enhanced discrimination and target identification abilities via the processing of returned inter-modulation products.

Abstract: A non-contact method for evaluating stress in a substrate. An impurity is non-uniformly introduced into at least one region of a crystalline substrate. The crystalline substrate is subjected to physical stress. Fluorescence producing energy is directed at the crystalline substrate. A fluorescence produced by the crystalline substrate is measured. The fluorescence is correlated with the stress on the crystalline substrate.

Abstract: A collection of logic gates that provide single event upset (SEU) immunity. The family of gates include an inverter, a two-input NOR gate, a two-input NAND gate, a three-input AND-NOR gate, and a three-input OR-NAND as well as a static RAM bit cell. SEU immunity is obtained by constructing each logic element with a redundant set of inputs and using two copies of each such logic element to provide redundant outputs. The design of a logic element is such that when the redundant inputs agree (i.e., each has the same logic value), then the output of the logic element implements the logic function. However, when any pair of redundant inputs disagree, then the output of the logic element is disconnected(tri-state), which preserves the previous output value. SEU events only affect one of the logic elements in the pair, and this upset can not propagate through other logic elements because of the tri-state function.

Abstract: A collection of logic gates that provide single event upset (SEU) immunity. The family of gates include an inverter, a two-input NOR gate, a two-input NAND gate, a three-input AND-NOR gate, and a three-input OR-NAND as well as a static RAM bit cell. SEU immunity is obtained by constructing each logic element with a redundant set of inputs and using two copies of each such logic element to provide redundant outputs. The design of a logic element is such that when the redundant inputs agree (i.e., each has the same logic value), then the output of the logic element implements the logic function. However, when any pair of redundant inputs disagree, then the output of the logic element is disconnected (tri-state), which preserves the previous output value. SEU events only affect one of the logic elements in the pair, and this upset can not propagate through other logic elements because of the tri-state function.

Abstract: A sensor array system for detecting the position of an object or energy source. The system includes a plurality of sensors, each sensor having a limited field of view and being capable of detecting an object or energy source that is positioned within its field of view. The fields of view of at least some of the sensors overlap the fields of view of other sensors, and the overlapping fields of view define unique spatial regions. A data acquisition system is operatively connected to the plurality of sensors and is used to determine which sensors simultaneously detect an object or energy source, thereby determining the unique spatial region in which the object or energy source is located.

Abstract: Disclosed is a system and method for increasing the weak signal recovery capability of a Global Positioning System (GPS) receiver correlating each of the plurality of digital signals by multiplying the I and Q phases by the carrier and code, adding a location offset, accumulating the results of the correlation, and latching the results until a predetermined time; coherent combining the accumulated results at the predetermined time; non-coherent combining the coherent combined results for a time period sufficient to raise a correlation peak to a predetermined point above a noise floor to produce a plurality of non-coherent bin observables; determining a maximum value of the plurality of bin observables and comparing the maximum value to predetermined threshold; determining grid locations of bin observables having maximum values greater than the predetermined threshold; determining a bi-quadratic surface using the grid locations; determining an argument maximum of the bi-quadratic surface; estimating epoch pseu

Abstract: An integrated navigation and communication system that enables distributed spacecraft system operations. The system is a modular, extensible system that supports science operations among multiple, distributed spacecraft by implementing the essential functions of navigation, communication and control. Distributed spacecraft systems, also called formation flying systems, extend the capabilities of single-spacecraft missions by providing a platform for complex sensing tasks, including multipoint observation, co-observation, and distributed apertures. To accomplish these tasks, the system enables spacecrafts within a distributed spacecraft system to communicate science and coordination information, to determine relative position, velocity and time for command and control operations, and to operate in a coordinated manner to achieve common mission goals.

Abstract: A controller for a quartz crystal microbalance (QCM) sensor system and method for detecting mass deposition on a QCM sensor. The controller controls a QCM using temperature-, voltage- and current-regulating circuits, a microcontroller, an oscillator, heating and cooling devices and circuits, high voltage grids, digital-to-analog and analog-to-digital converters, data telemetry and uplink circuits, and a remote user. The remote user may be a person, computer, network or data logger. The remote user allows the controller to be reconfigurable during operation. The controller samples and reports data faster and is more reliable over extended periods of operation. Further, the controller is assembled using innovative techniques making it smaller and thus more transportable, easier to incorporate into existing facilities and less expensive to construct and operate. The apparatus may also be assembled in a modular fashion that allows for customization.

Abstract: A method and apparatus for obtaining measurements, on a spacecraft that employs a transceiver, at intervals that are shorter than the telemetry frame duration for use in correcting ground-based Doppler measurements so as to remove the effects of drift in the spacecraft oscillator frequency reference. Samples of navigation counters on the spacecraft that supply information that may be used to compare the uplink frequency with the downlink frequency at the spacecraft are triggered at intervals that are shorter than the duration of a telemetry frame; the samples are then included in a telemetry frame and are time tagged after they are received on the ground; the time tagged samples are then used to calculate precise two-way Doppler measurements.

Abstract: A low-pressure valve enabling precise control of a fluid flow rate through the valve during cyclical operation of the valve. The valve is useful for controlling air delivery to a patient as part of a portable ventilator. The valve comprises a housing having an inlet 16 and two outlets 18 and 20. A wiper plate 22 and an orifice plate 24 are disposed inside of the housing. Transverse movement of the wiper plate 22 relative to the orifice plate 24, powered for example by a servomotor 34, simultaneously and alternatively covers and uncovers various openings 26 in the orifice plate 24. The total flow through the valve is thereby divided between the two outlets 78 and 20.