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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Gas Composition Sensing Using Carbon Nanotube Arrays

This innovation is a lightweight, small sensor for inert gases that consumes a relatively small amount of power and provides measurements that are as accurate as conventional approaches. The sensing approach is based on generating an electrical discharge and measuring the specific gas breakdown voltage associated with each gas present in a sample. 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 multi-wall carbon nanotubes (MWCNTs) or carbon nanofibers (CNFs), to generate high-strength electrical fields adjacent to the tips 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 sensor can be multiplexed to measure current from multiple CNT arrays for simultaneous detection of several gas components.

Li, Jing↗
NASA NTRS2012

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor's accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Nguyen, Truong X.↗
NASA NTRS2012

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor s accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Nguyen, Truong X.↗
NASA NTRS2008

Self-Powered Wireless Sensors

NASA's integrated vehicle health management (IVHM) program offers the potential to improve aeronautical safety, reduce cost and improve performance by utilizing networks of wireless sensors. Development of sensor systems for engine hot sections will provide real-time data for prognostics and health management of turbo-engines. Sustainable power to embedded wireless sensors is a key challenge for prolong operation. Harvesting energy from the environment has emerged as a viable technique for power generation. Thermoelectric generators provide a direct conversion of heat energy to electrical energy. Micro-power sources derived from thermoelectric films are desired for applications in harsh thermal environments. Silicon based alloys are being explored for applications in high temperature environments containing oxygen. Chromium based p-type Si/Ge alloys exhibit Seebeck coefficients on the order of 160 micro V/K and low thermal conductance of 2.5 to 5 W/mK. Thermoelectric properties of bulk and thin film silicides will be discussed

Dynys, Fred↗
NASA NTRS2023

Electronic Nose Development and Preliminary Human Breath Testing for Rapid, Non-Invasive COVID-19 Detection

We adapted an existing, spaceflight-proven, robust “electronic nose” (E-Nose) that uses an array of electrical resistivity-based nanosensors mimicking aspects of mammalian olfaction to conduct on-site, rapid screening for COVID-19 infection by measuring the pattern of sensor responses to volatile organic compounds (VOCs) in exhaled human breath. We built and tested multiple copies of a hand-held prototype E-Nose sensor system, composed of 64 chemically sensitive nanomaterial sensing elements tailored to COVID-19 VOC detection; data acquisition electronics; a smart tablet with software (App) for sensor control, data acquisition and display; and a sampling fixture to capture exhaled breath samples and deliver them to the sensor array inside the E-Nose. The sensing elements detect the combination of VOCs typical in breath at parts-per-billion (ppb) levels, with repeatability of 0.02% and reproducibility of 1.2%; the measurement electronics in the E-Nose provide measurement accuracy and signal-to-noise ratios comparable to benchtop instrumentation. Preliminary clinical testing at Stanford Medicine with 63 participants, their COVID-19-positive or COVID-19-negative status determined by concomitant RT-PCR, discriminated between these two categories of human breath with a 79% correct identification rate using “leave-one-out” training-and-analysis methods. Analyzing the E-Nose response in conjunction with body temperature and other non-invasive symptom screening using advanced machine learning methods, with a much larger database of responses from a wider swath of the population, is expected to provide more accurate on-the-spot answers. Additional clinical testing, design refinement, and a mass manufacturing approach are the main steps toward deploying this technology to rapidly screen for active infection in clinics and hospitals, public and commercial venues, or at home.

COVID-19↗
DOE OSTI2023

Advanced Long-Term Environmental Monitoring Systems (ALTEMIS) Artificial Intelligence Data Management Plan

Across the Department of Energy’s Environmental and Legacy Management sites, complex groundwater plumes exist that will require long-term monitoring to ensure remedial actions that have been put in place remain effective decades into the future. The current monitoring paradigm predominantly consists of groundwater well sampling, whereby samples are collected, concentrations analyzed, and plume anomalies are detected after they have occurred. The Advanced Long Term Environmental Monitoring Systems (ALTEMIS) program is a multi-lab, multi-institution team of researchers that is deploying spatially integrative technologies (i.e., real-time in situ sensor networks), coupled with artificial intelligence and machine learning, to establish a more proactive monitoring paradigm. Within this approach, plume anomalies can be predicted, and corrective actions can be established prior to the occurrence, offering a more cost-effective and robust approach to long-term monitoring. The team has deployed a variety of different in situ sensing technologies at the Savannah River Site’s F-Area Hazardous Waste Management Facility around the F-Area Seepage Basins, which are unlined basins that received 7 billion liters of acidic low-level radioactive waste from the 1950s until the late 1980s. The technologies and techniques that the team is deploying are intended to ensure that the remedial actions that have been taken by the site remain effective decades into the future. Foundational to this approach is a robust, integrated data management and analysis plan to ensure accurate and timely reporting from the variety of sensor systems that are in place. This report will outline the data management plan that has been implemented by the ALTEMIS team at the Savannah River Site and will serve as a blueprint as the technology is translated to new sites across the DOE Complex.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2008

Assessment of MODIS Scan Mirror Reflectance Changes On-Orbit

Since launch, the NASA EOS Terra and Aqua MODIS have operated successfully for more than 8 and 6 years, respectively. MODIS collects data using a two-sided scan mirror over a large scan angular range. The scan mirror is made of a polished, nickel-plated beryllium base coated with high purity silver, which is then over-coated with the Denton proprietary silicon monoxide and silicon dioxide mixture. The scan mirror's reflectance was characterized pre-launch using its witness samples, and the response versus scan angle was measured at the sensor system level. In this study, we present an assessment of MODIS scan mirror on-orbit degradation by examining changes of spectral band response over each sensor's mission lifetime. Results show that the scan mirror's optical properties for both Terra and Aqua MODIS have experienced significant degradation since launch in the VIS spectral region, which is mirror side dependent as well as scan angle dependent. In general, the mirror degradation is more severe for Terra MODIS than Aqua MODIS, especially during recent years. For Terra MODIS, the degradation rate is noticeably different between the mirror sides. On the other hand, there has been little mirror side dependent difference for Aqua MODIS.

Xiong, Xiaoxiong↗
NASA NTRS2008

Nanosensors for Evaluating Hazardous Environments

Personnel working in a confined environment can be exposed to hazardous gases, and certain gases can be extremely dangerous even in concentrations as low as a few parts per billion. Nanosensors can be placed in multiple locations over a large area, thus allowing for more precise and timely detection of gas leaks. ASRC Aerospace and its research partners are developing nanosensors to detect various gases, including hydrogen, ammonia, nitrogen tetroxide, and hydrazine. Initial laboratory testing demonstrated the capability to detect these gases in concentrations lower than parts per million, and current testing is evaluating sensitivity at concentration levels three orders of magnitude lower. Testing and development continue to improve the response and recovery times and to increase the sensitivity of the devices. The development team is evaluating different coatings and electrodes to determine the optimum configuration for detecting and identifying a variety of gases. The small footprint of the nanosensors allows several devices to be placed into a single substrate. Each sensor is responsive in a different way to different gases. Embedding multiple devices into a single substrate results in better reliability and less frequent calibrations. The use of different coatings for individual elements of a multichannel sensor allows different gases to be identified. The sensor system is implemented by the use of a custom multichannel signal conditioner amplifier built on a small multichip module. This device processes the output of the sensors and transmits a signal that can be monitored and analyzed remotely.

Source record↗
DOE OSTI2020

Development and Test of High Temperature Surface Acoustic Wave Gas Sensors

The demand for sensors in hostile environments, such as power plant environments, aerospace environments, oil and gas extraction, and high-temperature metallurgy environments, has risen over the past decades in a continuous attempt to increase process control, improve energy and process efficiency in production, reduce operational and maintenance costs, increase safety, and perform condition-based maintenance in equipment and structures operating in high-temperature harsh-environment conditions. The increased reliability, improved performance, and development of new sensors and networks with a multitude of components, especially wireless networks, are the target for operation in harsh environments. Gas sensors, in particular H2 sensors, operating above 200 C are required in the instrumentation, process control and general safety of a number of industries including coal, natural gas, and nuclear power generation facilities, the aerospace and automotive industries, metallurgical production and defense-related applications. The surface acoustic wave (SAW) platform is a particularly promising option for high-temperature, harsh-environment gas sensing applications since the platform exhibits advantages, such as battery-free and wireless operation, small size, possibility for scale production using well-developed technologies from the semiconductor industry, and low cost of installation and operation. In this work, one-port SAW resonators (SAWRs) operating along five different orientations on a commercially available langasite (LGS) wafer employing Pt-Al2O3 electrodes and reflectors were designed, fabricated, and used as high-temperature H2 sensors. Two of the selected orientations were predicted and confirmed to have temperature-compensated operation above 150 C. A gas sensor test setup was developed, capable of gas cycling between N2, O2 and N2/H2 mixtures under extended high-temperature periods (up to 650 C for over 20 hours). Thin film Pt-Al2O3 was used as the electrode material for the transducers and reflectors capable of high-temperature operation, and also as H2 sensing film. In addition, yttria-stabilized zirconia (YSZ) thin films with Pt decoration were tested as sensing films aimed to enhance the SAWR sensor response to H2. The SAW devices were monitored in excess of 1700 hours in real-time during gas cycling sequences up to 600 C, leading to the following findings: i) the Pt-Al2O3 electrodes performed better for H2 sensing than the Pt-decorated YSZ sensing film, showing as much as 50% higher frequency variation response in the 200 C to 400 C range; ii) different crystallographic orientations operating on the same LGS wafer experienced different responses to H2 exposures up to 500 C; iii) the surface oxidation state of the SAWR sensors was shown to have an important impact on subsequent H2 exposure responses. In addition, a sensor system employing two LGS SAWRs, aligned along two different orientations, has been developed to simultaneously determine H2 presence and temperature. Finally, wireless interrogation of a SAWR sensor was successful within the gas cycling test fixture, and successful wireless H2 detection was achieved above 400 C.

Ayes Moncada, Armando↗
DOE OSTI2022

System and method thermopile energy harvesting for subsurface well bore sensors

A system and method for powering a borehole sensor with thermal energy is disclosed. The system includes a tubular pipe inserted into a subsurface borehole. A borehole casing is coaxially disposed with the tubular pipe. An annular space between the casing and the tubular pipe has a power source placed in the borehole to power a sensor in response to a temperature gradient between a surface of the casing and a surface of the tubular pipe. The method includes attaching thermopiles on the borehole casing or tubing; placing the thermopile in the annulus between the casing and the tubing; inducing a thermal gradient across the thermopile; generating an electrical energy in response to the temperature gradient; powering the sensor from the generated energy; and monitoring vertical expansion of a CO2 plume.

Bryan, Charles R.↗
NASA NTRS2008

Intelligent Sensors for Integrated Systems Health Management (ISHM)

IEEE 1451 Smart Sensors contribute to a number of ISHM goals including cost reduction achieved through: a) Improved configuration management (TEDS); and b) Plug-and-play re-configuration. Intelligent Sensors are adaptation of Smart Sensors to include ISHM algorithms; this offers further benefits: a) Sensor validation. b) Confidence assessment of measurement, and c) Distributed ISHM processing. Space-qualified intelligent sensors are possible a) Size, mass, power constraints. b) Bus structure/protocol.

Schmalzel, John L.↗
NASA NTRS2014

Multi-Dimensional Sensors and Sensing Systems

A universal microelectromechanical (MEMS) nano-sensor platform having a substrate and conductive layer deposited in a pattern on the surface to make several devices at the same time, a patterned insulation layer, wherein the insulation layer is configured to expose one or more portions of the conductive layer, and one or more functionalization layers deposited on the exposed portions of the conductive layer to make multiple sensing capability on a single MEMS fabricated device. The functionalization layers are adapted to provide one or more transducer sensor classes selected from the group consisting of: radiant, electrochemical, electronic, mechanical, magnetic, and thermal sensors for chemical and physical variables and producing more than one type of sensor for one or more significant parameters that need to be monitored.

Stetter, Joseph R.↗
DOE OSTI2020

Fault diagnosis and fault tolerant control for T-S fuzzy stochastic distribution systems subject to sensor and actuator faults

The problem of fault diagnosis (FD) and fault tolerant control (FTC) for a class of Takagi-Sugeno (T-S) fuzzy stochastic distribution control (SDC) systems subject to sensor and actuator faults is discussed in this paper. First, fuzzy logic models are used to approximate the output probability density function (PDF). Next, an adaptive augmented state/fault diagnosis observer is proposed to estimate the system state, sensor and the actuator faults simultaneously. New expected weights based on the sensor fault estimation information and a PI-type fuzzy feedback fault tolerant (FT) controller are designed to compensate the effect of sensor fault and actuator fault simultaneously. When the sensor fault occurs, the expected objective is redesigned to compensate the sensor fault. Meanwhile, the PI controller can compensate the effect of actuator fault, and the output PDF of the system can still track the desired PDF after the fault occurs. Finally, an example of quality distribution control in chemical reaction process is given to confirm the effectiveness of the algorithm.

42 ENGINEERING↗
NASA NTRS2015

Partnership Opportunities with AFRC for Wireless Systems Flight Testing

The presentation will overview the flight test capabilities at NASA Armstrong Flight Research Center (AFRC), to open up partnership collaboration opportunities for Wireless Community to conduct flight testing of aerospace wireless technologies. Also, it will brief the current activities on wireless sensor system at AFRC through SBIR (Small Business Innovation Research) proposals, and it will show the current areas of interest on wireless technologies that AFRC would like collaborate with Wireless Community to further and testing.

sensors↗
NASA NTRS1988

Sampling data for OSSEs

An OSSE should for the sake of realism incorporate at least some of the high-frequency, small-scale phenomena that are suppressed by atmospheric models; these phenomena should be present in the realistic atmosphere sampled by all observing sensor systems whose data are being used. Errors are presently generated for an OSSE in a way that encompasses representational errors, sampling, geophysical local bias, random error, and sensor filtering.

Hoffman, Ross↗
NASA NTRS1991

Segmented mirror figure control for a space-based far-IR astronomical telescope

For segmented large mirrors to be used effectively for astronomy they must be actively aligned and controlled to extreme levels of precision. We consider the figure control problem for a spaceborne far-IR telescope, the Precision Segmented Reflector Project Focus Moderate Mission Telescope. We propose a two-stage approach. A figure initialization controller is used to achieve initial phasing and alignment of the telescope using an imaging science detector. A figure maintenance controller keeps the telescope aligned during normal operation using a laser metrology optical truss sensor system. We show that performance of any figure control system is subject to limits on the controllability of the wavefront. Maintenance controllers are additionally limited by considerations of the observability of the wavefront from the maintenance sensors. We show preliminary results for the figure initialization controller. We present a 'Wavefront Compensation' method for figure maintenance control that minimizes wavefront errors due to misalignment errors.

Redding, David↗
DOE OSTI2024

Initial PIP-II Beam Current Monitor Fault Case Analyses & Beam Position Monitor Linearity Studies in CST Studio Suite

The use of non-invasive sensors & systems to measure particle beam characteristics is a crucial part of modern accelerator control systems due to their ability to return real time beam data while minimizing negative effects on beam quality. To ensure that one can be reasonably confident these sensors will behave as desired upon be-ing implemented within the beamline, simulations pre-dicting the performance of these sensors under beamline conditions can be used as a valuable tool for checking sensor functionality without a physical test bench. This paper details the design, testing, and results of two sensor models developed using CST Studio Suite soft-ware designed to mimic two sensors to be implemented within the PIP-III beamline: an elliptical, large-aperture beam position monitor (BPM) for which vertical & hori-zontal position signal linearity was analyzed, and an AC current transformer (ACCT) beam current monitor (BCM) used to search for potential fault cases within the BCM and beam pipe flange gaps. Special focus is given to the discovery of linearity variations within the BPM and the use of frequency domain techniques in the BCM fault case analyses.

Rouzky, A. R.↗
NASA NTRS2011

Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing

Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed.

Hewagama, TIlak↗