Mechanical or electronic devices used to measure or receive stimulus in the form of light, temperature, pressure, sound, radiation level, or the like, convert that stimulus into an electronic signal and transmit the signal to a measuring or control instrument.
Adaptive Spatial Resolution Enables Focused Fiber Optic Sensing
This technology can be applied to most optical frequency domain reflectometry (OFDR) fiber optic strain sensing systems. It is particularly well suited to Armstrong's FOSS technology, which uses efficient algorithms to determine from strain data in real time a variety of critical parameters, including twist and other structural shape deformations, temperature, pressure, liquid level, and operational loads. <b><i>How It Works</b></i> This technology enables smart-sensing techniques that adjust parameters as needed in real time so that only the necessary amount of data is acquired—no more, no less. Traditional signal processing in fiber optic strain sensing systems is based on fast Fourier transform (FFT), which has two key limitations. First, FFT requires having analysis sections that are equal in length along the whole fiber. Second, if high resolution is required along one portion of the fiber, FFT processes the whole fiber at that resolution. Armstrong's adaptive spatial resolution innovation makes it possible to efficiently break up the length of the fiber into analysis sections that vary in length. It also allows the user to measure data from only a portion of the fiber. If high resolution is required along one section of fiber, only that portion is processed at high resolution, and the rest of the fiber can be processed at the lower resolution. <b><i>Why It Is Better</b></i> To quantify this innovation's advantages, this new adaptive method requires only a small fraction of the calculations needed to provide additional resolution compared to FFT (i.e., thousands versus millions of additional calculations). This innovation provides faster signal processing and precision measurement only where it is needed, saving time and resources. The technology also lends itself well to long-term bandwidth-limited monitoring systems that experience few variations but could be vulnerable as anomalies occur. More importantly, Armstrong's adaptive algorithm enhances safety, because it automatically adjusts the resolution of sensing based on real-time data. For example, when strain on a wing increases during flight, the software automatically increases the resolution on the strained part of the fiber. Similarly, as bridges and wind turbine blades undergo stress during big storms, this algorithm could automatically adjust the spatial resolution to collect more data and quickly identify potentially catastrophic failures. This innovation greatly improves the flexibility of fiber optic strain sensing systems, which provide valuable time and cost savings to a range of applications. <b><i>For more information about the full portfolio of FOSS technologies, see DRC-TOPS-37 or visit <a href=https://technology-afrc.ndc.nasa.gov/featurestory/fiber-optic-sensing>https://technology-afrc.ndc.nasa.gov/featurestory/fiber-optic-sensing</a></b></i>
Gas Composition Sensing Using Carbon Nanotube Arrays
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.
Novel Solid-State Humidity Sensor
NASA’s novel ceramic dielectric material enables extremely high-sensitivity humidity sensing. The ceramic sensing element is robust, can be manufactured using printing processes, and exhibits fast response and recovery speeds with large capacitance and resistance response/change per relative humidity unit change across a wide range of humidity levels in a log-linear response. Preliminary test data conducted in a humidity test chamber show a log-linear measured response in capacitance from 5 nanofarads (at 30% relative humidity, room temperature) to 0.2 millifarads (at 90% relative humidity, room temperature). The inventors discovered the humidity sensing element technology during their efforts to develop next-generation energy storage materials and devices for NASA. The inventors were initially puzzled by large swings in capacitance observed over the course of any given day in one particular dielectric composition, and, ultimately, they were able to trace these unexpected changes in capacitance back to corresponding changes in ambient humidity, even those occurring from breathing and exhalation. The sensor element can be formed using a dielectric ink or paste formulation, also developed by NASA, via traditional screen printing or advanced ink jet, aerosol, or 3D printing methods. The printed sensor element can be very thin, on the order of microns in thickness, with a small footprint, one square centimeter or less.
Impact and Trajectory Detection System
The Impact and Trajectory Detection System can indicate the time and location of an impact and the trajectory of that projectile using piezoelectric polymer film and sensors. The technology is designed so that the piezoelectric film covers the area of interest, regardless of size. This film has the characteristic that when it is mechanically impacted, it develops an electrical voltage, which can be detected. When a target area of concern is covered by this film, it will give an indication of a projectile strike. By dividing the area into pixels, and attaching sensors to each pixel, the impact location and time can be obtained. A computer connected to the system communicates with the electronics, processes the raw data, and displays the raw and processed data to the system user. The system uses a communication and control subsystem that upon projectile impact, performs a time discrimination analysis to determine the projectiles impacts location on each panel layer and the direction or trajectory of the projectile. This information can help in determining future safety measures and location placement for the area of interest. This system is light in weight and sensitive to a wide range of impact energies and velocities. The sensor has been extensively tested and works well in vacuum conditions, ambient conditions, or under pressure conditions and can exist passively through the piezoelectric effect. The electronics do require power, but they typically consumes very low wattage. Temperature limits have minimal effect on the piezofilm and the accuracy of the film is almost 100 percent. Systems of this type could be useful in settings in which the occurrence of impacts and/or the locations of impacts are not immediately obvious and there are requirements to detect and quickly locate impacts to prevent or minimize damage.
Frequency Diversity Pulse Pair Algorithm for Mitigation of Radar Range-Doppler Ambiguity
This technology mitigates the Doppler ambiguity by creating an innovative frequency. This frequency diversity technique takes advantage of the recent development in digital waveform generation and digital receiver technologies by transmitting a pair of pulses (or more pulses) with slightly shifted center frequencies in each pulse repetition period. Radar return signals from these pulses can be separated by the digital filters implemented in the digital receiver. In Doppler radar operation, the maximum unambiguous range is determined by the radar transmission pulse repetition time. This unique frequency diversity technique is implemented by alternating the order of the pulse pair with center frequencies as f1, f2, and f2, f1, then integrate the phase estimates of f1/f2 pulse pair and f2/f1 pulse pair in equal numbers. This approach will cancel the phase shift as a function of range between the pulses to enable the retrieval of Doppler phase. Although this method is more advanced, it also has its inherent limits, such as increased phase error and increased complexity in radar hardware to transmit and receive dual polarized signals. Despite its faults, it is a step forward in the evolution of the Doppler radar and its growing applications.
CAVITY ENHANCED ABSORPTION SPECTROSCOPY (CEAS) FOR OZONE DETECTION
This technique takes advantage of Ozone's strong absorption at specific wavelengths in the UltraViolet (UV). To take measurements, UV light is projected through a cell bounded by highly reflective mirrors. These mirrors increase the path length of the cell by inducing the light to bounce back and forth within the cell, increasing the likelihood of Ozone absorption within the cell. Finally, an absorption measurement is taken via a detector outside the cell and opposite of the UV source. This innovation produces an ozone detection precision of 0.12 parts per billion (ppb) in 0.1 second integration. This corresponds to 0.012 ppb in ten seconds integration.
Detection Of Presence Of Chemical Precursors
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.
Gateway Integrates Wireless Sensors with Existing Aircraft Systems at "the Speed of Software"
In traditional hardwired avionics systems, sensor integration requires installation of literally tons of physical cable that significantly increases vehicle weight and the time it takes to develop, maintain, and modify systems. Cabling also consumes space available for profitable payloads. Armstrong's technology uses software to incorporate new wireless capability without physically modifying existing avionics. <b><i>How It Works</b></i> Armstrong's gateway uses a software defined radio (SDR) to control the flow of information between various wireless devices and a vehicle's avionics. An SDR can be reprogrammed to communicate with a variety wireless communication protocols and frequencies via straightforward software modules—as opposed to wireless sensor-specific hardware—effectively eliminating the need to modify a vehicle's existing avionics hardware architecture. The gateway employs publish-subscribe network architecture. Before takeoff, flight computers reques—tor subscribe to—specific pieces of information from the SDR gateway. Wireless sensor devices then provide their respective sensor measurements to the SDR gateway, where they are distributed—or published—to any flight computer that has subscribed to a specific measurement. <b><i>Why It Is Better</b></i> Armstrong's technology simplifies the process of designing wireless avionics networks by providing a single point of communication between wireless and wired systems. It functions as a layer of abstraction between wireless sensors and the system with which they interface. This approach also ensures that no wireless device can directly communicate with a flight computer unless subscribed prior to takeoff, thus protecting the system from malicious or errant transmissions. Although specifically designed for aerospace systems, the gateway is both platform- and implementation-agnostic, with the potential to foster convergence between wireless technologies and existing systems in other industries. A manufacturer can add industrial Internet-of-Things capability without having to integrate new wireless interfaces into its preexisting network. The gateway serves as a universal interface with virtually any wireless device for such applications as connected logistics, predictive maintenance, asset tracking, and much more.
Sodium LIDAR for Spaceborne Missions
The instrument consists of a high-energy laser transmitter at 589 nm and highly sensitive photon counting detector that allows for range-resolved atmospheric-sodium-temperature profiles. The atmospheric temperature is deduced from the linewidth of the resonant fluorescence from the atomic sodium vapor D2 line as measured by the tunable laser. A high power energy laser allows for some daytime sodium LIDAR observations when used with a narrow bandpass filter based on etalon or atomic sodium Faraday filters with ~5 to 10 pm optical bandwidth.
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