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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

A Miniaturized Video System for Monitoring Drosophila Behavior

Long-term spaceflight may induce a variety of harmful effects in astronauts, resulting in altered motor and cognitive behavior. The stresses experienced by humans in space - most significantly weightlessness (microgravity) and cosmic radiation - are difficult to accurately simulate on Earth. In fact, prolonged and concomitant exposure to microgravity and cosmic radiation can only be studied in space. Behavioral studies in space have focused on model organisms, including Drosophila melanogaster. Drosophila is often used due to its short life span and generational cycle, small size, and ease of maintenance. Additionally, the well-characterized genetics of Drosophila behavior on Earth can be applied to the analysis of results from spaceflights, provided that the behavior in space is accurately recorded. In 2001, the BioExplorer project introduced a low-cost option for researchers: the small satellite. While this approach enabled multiple inexpensive launches of biological experiments, it also imposed stringent restrictions on the monitoring systems in terms of size, mass, data bandwidth, and power consumption. Suggested parameters for size are on the order of 100 mm3 and 1 kg mass for the entire payload. For Drosophila behavioral studies, these engineering requirements are not met by commercially available systems. One system that does meet many requirements for behavioral studies in space is the actimeter. Actimeters use infrared light gates to track the number of times a fly crosses a boundary within a small container (3x3x40 mm). Unfortunately, the apparatus needed to monitor several flies at once would be larger than the capacity of the small satellite. A system is presented, which expands on the actimeter approach to achieve a highly compact, low-power, ultra-low bandwidth solution for simultaneous monitoring of the behavior of multiple flies in space. This also provides a simple, inexpensive alternative to the current systems for monitoring Drosophila populations in terrestrial experiments, and could be especially useful in field experiments in remote locations. Two practical limitations of the system should be noted: first, only walking flies can be observed - not flying - and second, although it enables population studies, tracking individual flies within the population is not currently possible. The system used video recording and an analog circuit to extract the average light changes as a function of time. Flies were held in a 5-cm diameter Petri dish and illuminated from below by a uniform light source. A miniature, monochrome CMOS (complementary metal-oxide semiconductor) video camera imaged the flies. This camera had automatic gain control, and this did not affect system performance. The camera was positioned 5-7 cm above the Petri dish such that the imaging area was 2.25 sq cm. With this basic setup, still images and continuous video of 15 flies at one time were obtained. To reduce the required data bandwidth by several orders of magnitude, a band-pass filter (0.3-10 Hz) circuit compressed the video signal and extracted changes in image luminance over time. The raw activity signal output of this circuit was recorded on a computer and digitally processed to extract the fly movement "events" from the waveform. These events corresponded to flies entering and leaving the image and were used for extracting activity parameters such as inter-event duration. The efficacy of the system in quantifying locomotor activity was evaluated by varying environmental temperature, then measuring the activity level of the flies.

Bhattacharya, Sharmila↗
NASA NTRS2011

Two Catalysts for Selective Oxidation of Contaminant Gases

Two catalysts for the selective oxidation of trace amounts of contaminant gases in air have been developed for use aboard the International Space Station. These catalysts might also be useful for reducing concentrations of fumes in terrestrial industrial facilities especially facilities that use halocarbons as solvents, refrigerant liquids, and foaming agents, as well as facilities that generate or utilize ammonia. The first catalyst is of the supported-precious-metal type. This catalyst is highly active for the oxidation of halocarbons, hydrocarbons, and oxygenates at low concentrations in air. This catalyst is more active for the oxidation of hydrocarbons and halocarbons than are competing catalysts developed in recent years. This catalyst completely converts these airborne contaminant gases to carbon dioxide, water, and mineral acids that can be easily removed from the air, and does not make any chlorine gas in the process. The catalyst is thermally stable and is not poisoned by chlorine or fluorine atoms produced on its surface during the destruction of a halocarbon. In addition, the catalyst can selectively oxidize ammonia to nitrogen at a temperature between 200 and 260 C, without making nitrogen oxides, which are toxic. The temperature of 260 C is higher than the operational temperature of any other precious-metal catalyst that can selectively oxidize ammonia. The purpose of the platinum in this catalyst is to oxidize hydrocarbons and to ensure that the oxidation of halocarbons goes to completion. However, the platinum exhibits little or no activity for initiating the destruction of halocarbons. Instead, the attack on the halocarbons is initiated by the support. The support also provides a high surface area for exposure of the platinum. Moreover, the support resists deactivation or destruction by halogens released during the destruction of halocarbons. The second catalyst is of the supported- metal-oxide type. This catalyst can selectively oxidize ammonia to nitrogen at temperatures up to 400 C, without producing nitrogen oxides. This catalyst converts ammonia completely to nitrogen, even when the concentration of ammonia is very low. No other catalyst is known to oxidize ammonia selectively at such a high temperature and low concentration. Both the metal oxide and the support contribute to the activity and selectivity of this catalyst.

Wright, John D.↗
NASA NTRS2011

Performance of a 100V Half-Bridge MOSFET Driver, Type MIC4103, Over a Wide Temperature Range

The operation of a high frequency, high voltage MOSFET (metal-oxide semiconductor field-effect transistors) driver was investigated over a wide temperature regime that extended beyond its specified range. The Micrel MIC4103 is a 100V, non-inverting, dual driver that is designed to independently drive both high-side and low-side N-channel MOSFETs. It features fast propagation delay times and can drive 1000 pF load with 10ns rise times and 6 ns fall times [1]. The device consumes very little power, has supply under-voltage protection, and is rated for a -40 C to +125 C junction temperature range. The floating high-side driver of the chip can sustain boost voltages up to 100 V. Table I shows some of the device manufacturer s specification.

Patterson, Richard L.↗
NASA NTRS2011

Measuring Input Thresholds on an Existing Board

A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and temperatures to show that the interface had voltage margin under all worst case conditions. Gate input thresholds are normally measured at the manufacturer when the device is on a chip tester. A key function of this machine was duplicated on an existing flight board with no modifications to the nets to be tested, with the exception of changes in the FPGA program.

Kuperman, Igor↗
NASA NTRS2012

High-Speed Scanning Interferometer Using CMOS Image Sensor and FPGA Based on Multifrequency Phase-Tracking Detection

A sub-aperture stitching optical interferometer can provide a cost-effective solution for an in situ metrology tool for large optics; however, the currently available technologies are not suitable for high-speed and real-time continuous scan. NanoWave s SPPE (Scanning Probe Position Encoder) has been proven to exhibit excellent stability and sub-nanometer precision with a large dynamic range. This same technology can transform many optical interferometers into real-time subnanometer precision tools with only minor modification. The proposed field-programmable gate array (FPGA) signal processing concept, coupled with a new-generation, high-speed, mega-pixel CMOS (complementary metal-oxide semiconductor) image sensor, enables high speed (>1 m/s) and real-time continuous surface profiling that is insensitive to variation of pixel sensitivity and/or optical transmission/reflection. This is especially useful for large optics surface profiling.

Ohara, Tetsuo↗
NASA NTRS2011

An Set-Free, All Digital Controlled Point-of-Load Regulator for Next Generation Power Systems: ADC-POL

This paper presents a digitally controlled programmable point-of-load regulator for next-generation power systems. A novel digital control scheme was designed to minimize single-event effect (SEE)-induced transient effects. By effectively programming the loop transmission, the POL can trade off transient response time with SET robustness. The IC works with 1 to 5.5 V input voltage, 1-4.5V regulated output voltage, high efficiency (peak efficiency at 94%) and power of up to 5 W. The design was fabricated in the AMI i2t100 0.7 mu m complimentary, metal-oxide semiconductor (CMOS) process and characterized with the Jet Propulsion Laboratory (JPL) pulsed laser system.

Digital Signal Processing (DP)↗
NASA NTRS2015

Precision of FLEET Velocimetry Using High-Speed CMOS Camera Systems

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 microseconds, precisions of 0.5 meters per second in air and 0.2 meters per second in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision HighSpeed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

Peters, Christopher J.↗
NASA NTRS2015

Precision of FLEET Velocimetry Using High-speed CMOS Camera Systems

Femtosecond laser electronic excitation tagging (FLEET) is an optical measurement technique that permits quantitative velocimetry of unseeded air or nitrogen using a single laser and a single camera. In this paper, we seek to determine the fundamental precision of the FLEET technique using high-speed complementary metal-oxide semiconductor (CMOS) cameras. Also, we compare the performance of several different high-speed CMOS camera systems for acquiring FLEET velocimetry data in air and nitrogen free-jet flows. The precision was defined as the standard deviation of a set of several hundred single-shot velocity measurements. Methods of enhancing the precision of the measurement were explored such as digital binning (similar in concept to on-sensor binning, but done in post-processing), row-wise digital binning of the signal in adjacent pixels and increasing the time delay between successive exposures. These techniques generally improved precision; however, binning provided the greatest improvement to the un-intensified camera systems which had low signal-to-noise ratio. When binning row-wise by 8 pixels (about the thickness of the tagged region) and using an inter-frame delay of 65 micro sec, precisions of 0.5 m/s in air and 0.2 m/s in nitrogen were achieved. The camera comparison included a pco.dimax HD, a LaVision Imager scientific CMOS (sCMOS) and a Photron FASTCAM SA-X2, along with a two-stage LaVision High Speed IRO intensifier. Excluding the LaVision Imager sCMOS, the cameras were tested with and without intensification and with both short and long inter-frame delays. Use of intensification and longer inter-frame delay generally improved precision. Overall, the Photron FASTCAM SA-X2 exhibited the best performance in terms of greatest precision and highest signal-to-noise ratio primarily because it had the largest pixels.

Peters, Christopher J.↗
NASA NTRS2016

Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments

Silicon-Carbide device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon counterpart, Silicon-Carbide offers a greater possibility for high powered switching applications in extreme environment. In particular, Silicon-Carbide Metal-Oxide- Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing Silicon-Carbide power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.

Ikpe, Stanley A.↗
NASA NTRS2017

The High Definition Earth Viewing (HDEV) Payload

The High Definition Earth Viewing (HDEV) payload enables long-term experimentation of four, commercial-of-the-shelf (COTS) high definition video, cameras mounted on the exterior of the International Space Station. The payload enables testing of cameras in the space environment. The HDEV cameras transmit imagery continuously to an encoder that then sends the video signal via Ethernet through the space station for downlink. The encoder, cameras, and other electronics are enclosed in a box pressurized to approximately one atmosphere, containing dry nitrogen, to provide a level of protection to the electronics from the space environment. The encoded video format supports streaming live video of Earth for viewing online. Camera sensor types include charge-coupled device and complementary metal-oxide semiconductor. Received imagery data is analyzed on the ground to evaluate camera sensor performance. Since payload deployment, minimal degradation to imagery quality has been observed. The HDEV payload continues to operate by live streaming and analyzing imagery. Results from the experiment reduce risk in the selection of cameras that could be considered for future use on the International Space Station and other spacecraft. This paper discusses the payload development, end-to- end architecture, experiment operation, resulting image analysis, and future work.

Muri, Paul↗
NASA NTRS2018

Low-Power, Chip-Scale, Carbon Dioxide Gas Sensors for Spacesuit Monitoring

N5 Sensors, Inc. through a Small Business Technology Transfer (STTR) contract award has been developing ultra-small, low-power carbon dioxide (CO2) gas sensors, suited for monitoring CO2 levels inside NASA spacesuits. Due to the unique environmental conditions within the spacesuits, such as high humidity, large temperature swings, and operating pressure swings, measurement of key gases relevant to astronaut's safety and health such as(CO2), is quite challenging. Conventional non-dispersive infrared absorption based CO2 sensors present challenges inside the spacesuits due to size, weight, and power constraints, along with the ability to sense CO2 in a high humidity environment. Unique chip-scale, nanoengineered chemiresistive gas-sensing architecture has been developed for this application, which can be operated in a typical space-suite environmental conditions. Unique design combining the selective adsorption properties of the nanophotocatalytic clusters of metal-oxides and metals, provides selective detection of CO2 in high relative humidity conditions. All electronic design provides a compact and low-power solution, which can be implemented for multipoint detection of CO2 inside the spacesuits. This paper will describe the sensor architecture, development of new photocatalytic material for better sensor response, and advanced structure for better sensitivity and shorter response times.

Rani, Asha↗
NASA NTRS2019

Performance Evaluation of High-Speed, Low-Side Gate Driver, FAN3122, over Extended Temperature Range

Emerging power metal-oxide semiconductor field-effect transistor (MOSFETs) based on silicon carbide and gallium nitride technology are finding widespread use in many electronic applications such as motor control and DC/DC converters due to their higher voltage, higher temperature tolerance, and higher frequency switching capabilities. To utilize these power devices and to meet circuit/system compactness, modularity, and operational functionality, gate drivers that provide unique attributes, such as fast switching and high-current handling capability, are needed. In addition, power systems geared for use in space mission applications require on-board devices to withstand exposure to extreme temperatures and wide thermal swings. Very little data, however, exist on the performance of such devices and circuits under extreme temperatures. In this work, the performance of a high-speed gate driver with potential use in controlling power-level transistors was evaluated under extreme temperatures and thermal cycling. The investigations were carried out to assess performance for potential use of this device in space exploration missions under extreme temperature conditions.

Wide Bandgap Semiconductors↗
NASA NTRS2019

Transparent Conducting Oxides as Cathodes in Li-O2 Batteries: A First Principles Computational Investigation

Li-O2 batteries have traditionally used carbon based electrodes (graphite, buckypaper) as the cathode of choice due toits good electrical conductivity, stability against non-aqueous electrolytes like dimethoxyethane (DME) and ease ofhandling. But, the carbon cathode also leads to formation of carbonate by-products that increase overpotentials duringcharging leading to degradation of the cathode and reduction of cyclability. Recent investigations have focused on using metal-oxides like SnO2, TiO2 as viable cathodes-alternatives in Li-O2 systems. In this paper, we investigate transparent conducting oxides (TCOs) as cathodes with focus on the interface between the TCO surfaces and the discharge product, Li2O2, in the Li-O2 battery using first principles computations.

transparent conducting oxides↗
NASA NTRS2010

Interim test status report for NEPP scaled CMOS

This document serves as the fiscal year end report for the NEPP scaled complementary metal-oxide semiconductor (CMOS) task. Much of the effort this year focused on development of test capability and initial collection of data on SDRAM devices. Since the system has only just begun (in the last four weeks) to gather data, this report focuses on the test system and preliminary results.

Guertin, Steven M.↗
NASA NTRSDate not supplied

Marangoni effect and its potential utilization in supporting lunar habitats and other extraterrestrial endeavors

Tears of wine is a phenomenon frequently observed as a ring of wine formed near the top of the glass generates droplets that fall back into the wine. This phenomenon can be explained by the Marangoni effect driven by the surface tension created via gradient on concentration and temperature along with the interface between two phases. Besides being observed while drinking wine, the Marangoni effect is crucial for welding metals, manufacturing integrated circuits, and growing crystals; the Marangoni effect might be also crucial in supporting lunar habitats and other extraterrestrial endeavors as vacuum and reduced gravity are expected to augment the Marangoni effect on extraterrestrial molten soil leading to sustainable extraterrestrial in-situ resources utilization (ISRU). Preliminary Marangoni effect assessment on molten lunar regolith was conducted via JSC-1A lunar regolith simulant under vacuum yielding a spontaneous upwards migration of a uniform molten thin-film front that climbed the crucible wall covering the entire wall’s surface and reaching the crucible’s top end. A temperature gradient within the melt’s bulk and along the crucible’s wall generates a surface tension large enough not only to form a meniscus within the three-phase junction (crucible’s wall, bulk melt, and vacuum) but also to supersede the gravitational force to create the upwards migration of a thin film front originated on the meniscus. The observed extensive wettability of the melt with the crucible surface, an additional key factor besides surface tension necessary to sustain upwards migration, is atypical to what it has been witnessed on molten JSC-1A lunar regolith simulant under non-vacuum conditions and smaller sample sizes. The unique formation and self-migration of a thin-film front could enable key ISRU processes such as thin-film coating, crystal growth, and feedstock generation for additive 3D printing. Further assessment on the higher-temperature vacuum-driven decomposition of the uniform thin-film front as it climbed the crucible’s wall revealed a significant decomposition of various simulant’s metal-oxide components into their respective oxygen and metal elements strengthening the feasibility of extraterrestrial generation and fractional separation of oxygen and metals/alloys with none or minimal need for terrestrial precursors. The Marangoni effect assessment on molten JSC-1A lunar regolith simulant clearly opens novel pathways in future extraterrestrial ISRU endeavors including manufacturing and mining. Extraterrestrial mining will require an operational approach completely different from the terrestrial one that heavily relies on not only mechanical excavation and transportation but also post-processing; an in-situ all-in-one process might be feasible via these two coupled phenomena, self-migration and decomposition.

J A Dominguez↗
DOE OSTI2024

Hydrothermally and thermally stable catalytic materials based on theta-alumina

A material and a method of making hydrothermally stable (catalytic) materials on the basis of theta-alumina support that is thermally and hydrothermally stable up to 1,150 C with metal, mixed metal-, metal-oxide nanoparticles dispersed upon it. Such materials did not lose significant amounts of their catalytic activity at temperature ranges for industrially relevant applications (including hydrocarbon oxidation, nitric oxide reduction, carbon monoxide oxidation) even after hydrothermal aging up to 1,150° C.

Khivantsev, Konstantin↗
DOE OSTI2023

Dynamic Evolution of Palladium Single Atoms on Anatase Titania Support Determines the Reverse Water–Gas Shift Activity

Research interest in single-atom catalysts (SACs) has been continuously rising. However, the lack of understanding of the dynamic behaviors of SACs during applications hinder catalyst development and mechanistic understanding. Herein, we report on the evolution of active sites over Pd/TiO 2 -anatase SAC (Pd 1 /TiO 2 ) in the reverse water-gas shift (rWGS) reaction. Combining kinetics, in-situ characterization, and theory, we show that at T ≥ 350 °C, the reduction of TiO 2 by H 2 alters the coordination environment of Pd, creating Pd sites with partially cleaved Pd-O interfacial bonds and a unique electronic structure that exhibit high intrinsic rWGS activity through the carboxyl pathway. The activation by H 2 is accompanied by the partial sintering of single Pd atoms (Pd 1 ) into disordered, flat, ~1 nm diameter clusters (Pd n ). The highly active Pd sites in the new coordination environment under H 2 are eliminated by oxidation, which, when performed at high temperature, also re-disperses Pd n and facilitates the reduction of TiO 2 . In contrast, Pd 1 sinters into crystalline, ~5 nm particles (Pd NP ) during CO treatment, deactivating Pd 1 /TiO 2 . During the rWGS reaction, the two Pd evolution pathways co-exist. The activation by H 2 dominates, leading to the increasing rate with time-on-stream, and steady-state Pd active sites similar with the ones formed under H 2 . Finally, this work demonstrates how the coordination environment and nuclearity of metal sites on a SAC evolve during catalysis and pre-treatments, and how their activity is modulated by these behaviors. These insights on SAC dynamics and structure-function relationship are valuable to mechanistic understanding and catalyst design.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High-Field Nuclear Magnetic Resonance (NMR) Spectroscopy

Nuclear magnetic resonance (NMR) is a non-destructive spectroscopic technique that provides detailed molecular structural information via the electronic environments of nuclei in materials. Higher magnetic field strengths enhance the resolution of NMR, enabling discernment of unique chemical environments that might not be possible at low fields. Herein, the application of high-field NMR to catalyst and electrochemical system characterization are detailed. A brief description of NMR and quadrupolar nuclei are presented where the effects of magnetic field are described. Examples of high-field NMR are provided with particular focus on employing NMR to elucidate the structure of oxides of aluminum and vanadium for catalyst applications. The role of high-field NMR to conduct challenging experiments for energy storage materials is also explored and numerous other nuclei which require high-field measurement are briefly summarized.

Catalyst, Spectroscopy, NMR, High-field, Quadrupol↗