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These needs are met by this invention, which provide easy stem and associated method for detecting one or more chemical precursors (components) of a multi-component explosive compound. Different carbon nanotubes (CNTs) are loaded (by doping, impregnation, coating, or other functionalization process) for detecting of different chemical substances that are the chemical precursors, respectively, if these precursors are present in a gas to which the CNTs are exposed. After exposure to the gas, a measured electrical parameter (e.g. voltage or current that correlate to impedance, conductivity, capacitance, inductance, etc.) changes with time and concentration in a predictable manner if a selected chemical precursor is present, and will approach an asymptotic value promptly after exposure to the precursor. The measured voltage or current are compared with one or more sequence soft heir reference values for one or more known target precursor molecules, and a most probable concentration value is estimated for each one, two, or more target molecules. An error value is computed, based on differences of voltage or current for the measured and reference values, using the most probable concentration values. Where the error value is less than a threshold, the system concludes that the target molecule is likely. Presence of one, two, or more target molecules in the gas can be sensed from a single set of measurements.

This technology is part of Armstrong's portfolio of fiber optic sensing technologies known as FOSS. The innovation leverages Armstrong's cutting edge work in this area, including its patented FBG interrogation system, which allows for a diverse set of engineering measurements in a single compact system. In addition to magnetic field, other measurements include structural shape and buckling modes, external loads, and cryogenic liquid level. The system and measurement technology is commercially available for research applications. In addition to capitalizing on the significant advancements in fiber optic and laser technologies that have been made to support the telecommunications industry, Armstrong has also partnered with UCLA's Active Materials Lab (AML) to tap their expertise in the field of magnetics. For more information about the full portfolio of FOSS technologies, see DRC-TOPS-37 or visit https://technology-afrc.ndc.nasa.gov/featurestory/fiber-optic-sensing

The advantage of using cardiac biometrics over existing methods is that heart signatures are more difficult to forge compared to other biometric devices. Iris scanners can be fooled by contact lenses and sunglasses, and a segment of the population does not have readable fingerprints due to age or working conditions. Previous electrocardiographic signals employed a single template and compared that template with new test templates by means of cross-correlation or linear-discriminant analysis.The benefit of this technology over competing cardiac biometric methods is that it is more reliable with a significant reduction in error rates. The benefit of this technology is that it creates a probabilistic model of the electrocardiographic features of a person instead of a single signal template of the average heartbeat. The probabilistic model described as Gaussian mixture model allows various modes of the feature distribution, in contrast to a template model that only characterizes a mean waveform. Another advantage is that the model uses both physiological and anatomical characterization of the heart, unlike other methods that mainly use only physiological characterization of the heart. By combining features from different leads, the heart of the person is better characterized in terms of anatomical orientation because each lead represents a different projection of the electrical vector of the heart. Thus, employing multiple electrocardiographic leads provides a better performance in subject verification or identification.

A resistor-type sensor was fabricated which has a network of cross-linked SWCNTs with purity over 99%. An ordinary cellulose paper used for filtration was employed as the substrate. The filter paper exhibits medium porosity with a flow rate of 60 mL/min and particle retention of 5-10m. The roughness and porosity of the papers are attractive because they increase the contact area with the ambient air and promote the adhesion to carbon nanotubes. The SWCNTs were functionalized with carboxylic acid (COOH) to render them hydrophilic, thus increasing the adhesion with the substrate. The functionalized SWCNTs were dispersed in dimethylformamide solution. The film composed of networks of cross-linked CNTs was formed using drop-cast coating followed by evaporation of the solvent. Adhesive copper foil tape was used for contact electrodes. Our sensors outperformed the oxide nanowire-based humidity sensors in terms of sensitivity and response/recovery times.

Advanced Coupled-cavity Etalon (ACE) significantly improves both in-band transmission and out-of-band rejection. In some cases, 12% more light is transmitted inside the passband and >3x more light is rejected outside the passband. Incorporating ACE into the recirculating etalon receiver (RER) improves performance significantly. ACE increases the wavelength resolution and enables closer channel spacing resulting in a very efficient, high resolution spectrometer. RACER has both high resolution and a high photon efficiency which allows flexibility for trading different combinations of reduced cross-talk and closer channel spacing.

Pressure sensors play an important role in engine maintenance and monitoring systems by diagnosing problems before they happen. To capture the most accurate data, however, these sensors must be placed directly on an engine. In order to withstand extreme temperature and vibration, traditional pressure sensor technologies are bulky and complex, lacking the on-board control of microsystem technologies. Glenn's new capacitive pressure sensor system and packaging is the first of its kind to achieve high-temperature capability while maintaining miniaturization. This novel system consists of a Clapp-type oscillator that is fabricated on a high temperature alumina substrate. It comprises a silicon carbide (SiC) nitride pressure sensor, a metal-semiconductor field-effect transistor, and one or more chip resistors, wire-wound inductors, and SiC metal-insulator-metal (MIM) capacitors. The pressure sensor is located in the tank circuit of the oscillator so that a variation in pressure causes a change in capacitance, thus altering the resonant frequency of the sensing system. The chip resistors, inductors, and MIM capacitors have been characterized at temperature and operational frequency, and exhibit less than 5% variance in electrical performance. The system, which can be installed with a borescope plug adaptor in an on-wing operating engine, has been extensively tested and proven to operate reliably under extreme conditions. Its compact size, wireless capability, and ability to provide real-time in-situ data acquisition make this technology a game-changer in next-generation maintenance and monitoring systems.

An array of carbon nanotubes (CNTs) in a substrate is connected to a variable-pulse voltage source. The CNT tips are spaced appropriately from the second electrode maintained at a constant voltage. A sequence of voltage pulses is applied and a pulse discharge breakdown threshold voltage is estimated for one or more gas components, from an analysis of the current-voltage characteristics. Each estimated pulse discharge breakdown threshold voltage is compared with known threshold voltages for candidate gas components to estimate whether at least one candidate gas component is present in the gas. The procedure can be repeated at higher pulse voltages to estimate a pulse discharge breakdown threshold voltage for a second component present in the gas. The CNTs in the gas sensor have a sharp (low radius of curvature) tip; they are preferably multiwall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the current collecting plate, such as a gold plated silicon wafer or a stainless steel plate for breakdown of the gas components with lower voltage application and generation of high current. The sensor system can provide a high-sensitivity, low-power-consumption tool that is very specific for identification of one or more gas components. The sensors can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

The Direction of Arrival Estimation Signal of Opportunity Receiver is a transceiver technology for small satellite and CubeSat platforms that enables maximization of antenna gain in a specific direction to receive desired signals and suppress signals from other directions. The receive is a four-channel transceiver system to be operating in a LEO orbit for receiving direct as well as reflected signal (signals reflected from the ground) of a communication satellite. An adaptive array processing is implemented to steer the receiver beam towards the GEO satellites as well as steer the antenna beam towards the ground. When the beam is steered towards the ground the receiver provides attenuation for the direct signal incident from the GEO satellite, thus isolating the reflected signal from the strong direct signal. Usually a simple pair of cross dipoles are used for receiving signals transmitted by communication satellites. One pair is used to receive direct signals and another pair is used receive reflected signals. These dipoles are ideally supposed to receive only the reflected signals from the ground. However, because of close proximity and strong coupling to each other through their mutual coupling and because of their broad beam patterns, these dipole antennas receive signals reflected from other targets, as well as the direct transmitted signal. Since the strength of direct signals will be above the strength of reflected signals, reflected signals typically are completely masked by the strong direct signals. The Direction of Arrival Estimation Signal of Opportunity Receiver maximizes antenna gain in a desired direction to maximize desired signal and suppress unwanted signals.

A time-varying electrical field E, having a root-mean-square intensity of 2rms, with a non-zero gradient in a direction transverse to the liquid or fluid flow direction, is produced by a nanostructure electrode array with a very high magnitude gradient near exposed electrode tips. A dielectrophoretic force causes the selected particles to accumulate near the electrode tips, if the medium and selected particles have substantially different dielectric constants. An insulating material surrounds most of the nanostructure electrodes, and a region of the insulating material surface is functionalized to promote attachment of the selected particle species to the surface. An electrical property value Z(meas) is measured at the functionalized surface, and is compared with a reference value Z(ref) to determine if the selected species particles are attached to the functionalized surface. An advantage of this innovation is that an array of nanostructure electrodes can provide an electric field intensity gradient that is one or more orders of magnitude greater than the corresponding gradient provided by a conventional microelectrode arrangement. As a result of the high magnitude field intensity gradients, a nanostructure concentrator can trap particles from high-speed microfluidic flows. This is critical for applications where the entire analysis must be performed in a few minutes.