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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Effect of Thermodynamic and Environmental Factors on Crystallization of DNA‐Origami Superlattices

The directed self‐assembly of nanoscale materials into ordered superlattices presents a powerful strategy for creating next‐generation materials with programmable mechanical, optical, and photonic properties. Deoxyribonucleic acid (DNA) origami has emerged as a versatile scaffold for encoding nanoscale geometry and guiding the crystallization of complex 3D architectures. However, a systematic understanding of the parameters that govern the efficiency and quality of superlattice formation remains limited. In this study, we utilize octahedral DNA nanoscale frames as a model system to investigate the relative influence of key factors, including buffer composition, ionic strength, frame concentration, and thermal annealing protocols, on the size, order, and reproducibility of the resulting superlattices. Our findings provide a quantitative framework to rationally optimize DNA‐based assembly pathways. Structural characterization via small‐angle x‐ray scattering (SAXS), scanning electron microscopy (SEM), and optical microscopy validates the quality and fidelity of the assembled lattices. Moreover, by templating these DNA frameworks into inorganic replicas, we establish general design principles that extend beyond biomolecular systems, providing a foundation for the synthesis of programmable materials in broader nanofabrication contexts.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS1969

Remote detection of CAT by infrared radiation

The remote detection of clear air turbulence (CAT) was investigated using an airborne scanning infrared spectrometer. Results of the flight tests indicated a high correlation between turbulence and temperature changes, and remote detection was obtained at distances up to 10 miles. Since CAT can extend horizontally over 50 miles, but is usually limited vertically to a few thousand feet, it is concluded that the best avoidance maneuver is a change in altitude.

Astheimer, R. W.↗
NASA NTRS1979

Analyses of earth radiation budget data from unrestricted broadband radiometers on the ESSA 7 satellite

Six months of data from the wide-field-of-view low resolution infrared radiometers on the Environmental Science Services Administration (ESSA) 7 satellite were analyzed. Earth emitted and earth reflected irradiances were computed at satellite altitude using data from a new in-flight calibration technique. Flux densitites and albedos were computed for the top of the earth's atmosphere. Monthly averages of these quantities over 100 latitude zones, each hemisphere, and the globe are presented for each month analyzed, and global distributions are presented for typical months. Emitted flux densities are generally lower and albedos higher than those of previous studies. This may be due, in part, to the fact that the ESSA 7 satellite was in a 3 p.m. Sun-synchronous orbit and some of the comparison data were obtained from satellites in 12 noon sun-synchronous orbits. The ESSA 7 detectors seem to smooth out spatial flux density variations more than scanning radiometers or wide-field-of-view fixed-plate detectors. Significant longitudinal and latitudinal variations of emitted flux density and albedo were identified in the tropics in a zone extending about + or - 25 deg in latitude.

Weaver, W. L.↗
NASA NTRS1989

Signal and data processing of small targets 1989; Proceedings of the Meeting, Orlando, FL, Mar. 27-29, 1989

The present conference on digital signal processing, association and filtering techniques, and multiple-sensor/multiple-tracking techniques, discusses single-frame velocity estimation, efficient target extraction for laser radar imagery, precision target tracking for small extended objects, IR clutter partitioning for matched filter design, the maximum-likelihood approach to gamma circumvention, position estimation for optical point targets using staring detector arrays, and a multiple-scan signal processing technique for area-moving target indication. Also discussed are a proportional integral estimator, the prediction of track purity in tracking performance evaluations, synchronization and fault-tolerance in a distributed tracker, the benefits of soft sensors and probabilistic fusion, and testing track initiation algorithms fusing two-dimensional tracks.

Drummond, Oliver E.↗
NASA NTRS1991

The development and evaluation of an alternative powder prepregging technique for use with LaRC-TPI/graphite composites

An alternative powder prepregging method for use with LaRC-TPI (a thermoplastic polyimide)/graphite composites is investigated. The alternative method incorporates the idea of moistening the fiber prior to powder coating. Details of the processing parameters are given and discussed. The material was subsequently laminated into small coupons which were evaluated for processing defects using electron microscopy. After the initial evaluation of the material, no major processing defects were encountered but there appeared to be an interfacial adhesion problem. As a result, prepregging efforts were extended to include an additional fiber system, XAS, and a semicrystalline form of the matrix. The semicrystalline form of the matrix was the result of a complex heat treating cycle. Using scanning electron microscopy (SEM), the fiber/matrix adhesion was evaluated in these systems relative to the amorphous/XAS coupons. Based on these results, amorphous and semicrystalline/AS-4 and XAS materials were prepregged and laminated for transverse tensile testing. The results of these tests are presented, and in an effort to obtain more information on the effect of the matrix, remaining semicrystalline transverse tensile coupons were transformed back to the amorphous state and tested. The mechanical properties of the transformed coupons returned to the values observed for the original amorphous coupons, and the interfacial adhesion, as observed by SEM, was better than in any previous sample.

Ogden, Andrea L.↗
NASA NTRS1992

Durability evaluation of photovoltaic blanket materials exposed on LDEF tray S1003

Several candidate protective coatings on Kapton and uncoated Kapton were exposed to the low Earth orbital (LEO) environment on the Long Duration Exposure Facility (LDEF) to determine if the coatings could be used to protect polymeric substrates from degradation in the LEO environment. The coatings that were evaluated were 700 A of aluminum oxide, 650 A of silicon dioxide, and 650 A of a 4 percent polytetrafluoroethylene-96 percent silicon dioxide mixed coating. All of the coatings evaluated were ion beam sputter deposited. These materials were exposed to a very low atomic oxygen fluence (4.8 x 10 exp 19 atoms/sq. cm) as a result of the experiment tray being located 98 degrees from the ram direction. As a result of the low atomic oxygen fluence, determination of a change in mass was not possible for any of the samples including the uncoated Kapton. There was no evidence of spalling of any of the coatings after the approximately 33,600 thermal cycles recorded for LDEF. The surface of the uncoated Kapton, however, did show evidence of grazing incidence texturing. There was a 7-8 percent increase in solar absorptance for the silicon dioxide and aluminum oxide coated Kapton and only a 4 percent increase for the mixed coating. It appears that the addition of a small amount of fluoropolymer may reduce the magnitude of absorptance increase due to environmental exposure. Thermal emittance did not change significantly for any of the exposed samples. Scanning electron microscopy revealed few micrometeoroid or debris impacts, but the impact sites found indicated that the extent of damage or cracking of the coating around the defect site did not extend beyond a factor of three of the impact crater diameter. This limiting of impact damage is of great significance for the durability of thin film coatings used for protection against the LEO environment.

Sharon K Rutledge↗
NASA NTRS1995

Cryogenic and Simulated Fuel Jet Breakup in Argon, Helium and Nitrogen Gas Flows

Two-phase flow atomization of liquid nitrogen jets was experimentally investigated. They were co-axially injected into high-velocity gas flows of helium, nitrogen and argon, respectively, and atomized internally inside a two-fluid fuel nozzle. Cryogenic sprays with relatively high specific surface areas were produced, i.e., ratios of surface area to volume were fairly high. This was indicated by values of reciprocal Sauter mean diameters, RSMD's, as measured with a scattered- light scanning instrument developed at NASA Lewis Research Center. Correlating expressions were derived for the three atomizing gases over a gas temperature range of 111 to 422 K. Also, the correlation was extended to include waterjet breakup data that had been previously obtained in simulating fuel jet breakup in sonic velocity gas flow. The final correlating expression included a new dimensionless molecular-scale acceleration group. It was needed to correlate RSMD data, for LN2 and H2O sprays, with the fluid properties of the liquid jets and atomizing gases used in this investigation.

Ingebo, Robert D.↗
NASA NTRS1997

Spectroscopic observations of the extended corona during the SOHO whole sun month

The spatial distribution of plasma parameters in the extended corona, derived from the ultraviolet coronagraph spectrometer (UVCS) onboard the Solar and Heliospheric Observatory (SOHO), was investigated. The observations were carried out during the SOHO whole month campaign. Daily coronal scans in the H I Lyman alpha and O VI lambda-lambda 1032 A and 1037 A were used. Maps of outflow velocities of O(5+), based on Doppler dimming of the O VI lines, are discussed. The velocity distribution widths of O(5+) are shown to be a clear signature of coronal holes while the velocity distributions for H(0) show a much smaller effect. The possible physical explanations for some of the observed features are discussed.

Strachan, L.↗
DOE OSTI2023

Explainability and human intervention in autonomous scanning probe microscopy

The broad adoption of machine learning (ML)-based autonomous experiments (AEs) in material characterization and synthesis requires strategies development for understanding and intervention in the experimental workflow. Here, we introduce and realize a post-experimental analysis strategy for deep kernel learning-based autonomous scanning probe microscopy. This approach yields real-time and post-experimental indicators for the progression of an active learning process interacting with an experimental system. We further illustrate how this approach can be applied to human-in-the-loop AEs, where human operators make high-level decisions at high latencies setting the policies for AEs, and the ML algorithm performs low-level, fast decisions. The proposed approach is universal and can be extended to other techniques and applications such as combinatorial library analysis.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

RadVolViz: An Information Display-Inspired Transfer Function Editor for Multivariate Volume Visualization

In volume visualization transfer functions are widely used for mapping voxel properties to color and opacity. Typically, volume density data are scalars which require simple 1D transfer functions to achieve this mapping. If the volume densities are vectors of three channels, one can straightforwardly map each channel to either red, green or blue, which requires a trivial extension of the 1D transfer function editor. Here, we devise a new method that applies to volume data with more than three channels. These types of data often arise in scientific scanning applications, where the data are separated into spectral bands or chemical elements. Our method expands on prior work in which a multivariate information display, RadViz, was fused with a radial color map, in order to visualize multi-band 2D images. In this work, we extend this joint interface to blended volume rendering. The information display allows users to recognize the presence and value distribution of the multivariate voxels and the joint volume rendering display visualizes their spatial distribution. We design a set of operators and lenses that allow users to interactively control the mapping of the multivariate voxels to opacity and color. This enables users to isolate or emphasize volumetric structures with desired multivariate properties. Furthermore, it turns out that our method also enables more insightful displays even for RGB data. We demonstrate our method with three datasets obtained from spectral electron microscopy, high energy X-ray scanning, and atmospheric science.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Diamond encapsulated silicon optical fibers synthesized by chemical vapor deposition

Semiconductor optical fibers encapsulated in a protective diamond coating can theoretically lead to immense power handling capabilities and infrared functionality. Here, silicon optical fibers are grown using high pressure chemical vapor deposition before being coated by 50 μm–300 μm of diamond by microwave plasma-assisted chemical vapor deposition. This coating extends conformally around the fiber cross section with diamond crystallites in the film on the order of several micrometers. Complete coating of high-quality diamond around the fiber is indicated by scanning electron microscopy and Raman measurements. The encapsulated silicon fibers are durable enough to survive the diamond deposition process, as demonstrated by their ability to guide infrared light.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Data Analysis of X-ray Panels Used in X-ray CT Scientific Instruments

This report is a follow-up study on M. Skeate’s study on System Drift Detection for Health Monitoring (Skeate, 2023). The following report highlights analyses of the panel’s behavior with extended use. This includes effects of burn-in on the panel from over-use and bad pixels (defined in Methodology.) Using data-forward statistical analyses across a sequence of scans, and given that the other conditions present in the data can be replicated, this study show that overtime use of panels does not affect bad pixel count. Also, I present conclusive evidence of a direct relationship between the regions of the panel that are exposed to radiation and burn-in damage to that region overtime. Additionally, this study also highlights the effect of the duty cycle on the dark current change in the panel.

42 ENGINEERING↗
NASA NTRS1975

Development of a spectroscopic photoelectric imaging Fabry-Perot interferometer preliminary observational results

In order to observe extended astronomical objects at high spatial and spectral resolution, a spectroscopic photoelectric imaging Fabry-Perot interferometer was constructed. Among the properties chosen for the instrument are an air-spaced, piezoelectrically scanned design allowing an accurately settable free spectral range and employing a single etalon of high finesse. Careful design of the etalon mountings and optical train preserves high ligh throughput. Spectra of single spatial elements with a photomultiplier were obtained, and an SEC vidicon detector was used to record a series of images through the interferometer while scanning the wavelength in discrete steps. The latter procedure yields sufficient information to reconstruct spectral features over the entire object, and for the conditions assumed, either series of observations requires only a small fraction of a rotational period for Jupiter or Saturn. An electronic control system was also constructed which permits rapid and flexible variation of the operational mode of the Fabry-Perot and its ancilliary devices so as to minimize loss of observational time.

Smith, W. H.↗
NASA NTRS1979

Portable high-resolution laser monochromator-interferometer with multichannel electronic readout

A high-resolution 0.4-m monochromator is described for use in wavelength diagnosis of tunable pulsed and CW laser sources in the 3000-10,000-A region. The f/20 design uses an echelle grating in an over-and-under Ebert configuration with a scanned photodiode array to provide a real-time multichannel display of spectral output. Absolute wavelength may be determined to 0.1 A with the monochromator, and a Fabry-Perot interferometer attachment extends linewidth measurement capability to 0.01 A or better. Spectra are displayed on a storage oscilloscope, and calculation of laser parameters is explained. The instrument measures 70 cm long x 15 cm wide x 20 cm high.

Morris, M. B.↗
NASA NTRS2001

Textures of Secondary Alteration Zones in Nakhla

Textures of secondary minerals in cracks in Nakhla are described and illustrated with high resolution Scanning Electron Microscopy (SEM) and BSE. Some Nakhla textures resemble alteration textures of glass in seafloor basalts. Criteria for inorganic vs. biogenic alteration are discussed. Additional information is contained in the original extended abstract.

McKay, D. S.↗
NASA NTRS2009

An Overview of MODIS Calibration and Characterization and Lessons Learned

The Moderate Resolution Imaging Spectroradiometer (MODIS) is a key instrument for NASA's EOS missions. Two nearly identical copies have flown on the Terra and Aqua spacecraft for more than 9 years and 6 years since their launch in December 1999 and May 2002, respectively. MODIS observations and associated data products have been widely used by the science community and users worldwide for studies of Earth's system of land, oceans, and atmosphere. MODIS was developed based on the desire of the science community to extend and enhance heritage sensors' data records. It was designed with enhancements made over its heritage sensors in terms of its spectral, spatial, and radiometric characteristics. It is a cross-track scanning radiometer, that uses a two-sided scan mirror, collecting data in 36 spectral bands covering spectral regions of visible (VIS), near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR). The VIS, NIR, and SWIR bands (bands 1-19 and 26), which make measurements of daytime surface reflected radiances, are referred to as the reflective solar bands (RSB). The MWIR and LWIR bands (20-25 and 27-36), which measure both the daytime and nighttime scene emissive radiances, are thus referred to as the thermal emissive bands (TEB). In this paper, we provide an overview of MODIS instrument calibration and characterization methodologies, activities, and results from pre-launch to post launch, with emphasis on the lessons learned from its design to on-orbit operation. Currently, both instruments are operated normally and all the on-orbit calibration activities are performed on a regular basis with some at slightly reduced frequencies. The TEB responses have been extremely stable with less than 0.3% change per year. For the RSB, the changes are wavelength and scan angle dependent with the largest changes in the VIS spectral bands. As both Terra and Aqua MODIS continue to operate beyond their prime missions, constant effort is still needed to maintain instrument and calibration and data product quality. This paper shows that the lessons from Terra MODIS design, test, and operation, have greatly benefitted Aqua MODIS. Because of this, Aqua MODIS overall performance is better than Terra MODIS. It is not surprising that lessons from MODIS calibration and characterization, from methodologies to on-orbit implementation, have also provided valuable information for the design and development of future earth observing missions/sensors, such as VHRS on the NPP and NPOESS, ABI on GOES-R, OLI on LDCM, and the reflective solar sensor on CLARREO.

Xiong, Xiaxiong↗
NASA NTRSDate not supplied

Verifying PLC Programs via Monitors: Extending the Integration of FRET and PLCverif

Verification of Programmable Logic Controller (PLC) programs requires reasoning about propositions qualified in terms of time. CERN’s PLCverif, an open-source tool for the analysis of safety-critical PLC systems, uses Linear Temporal Logic (LTL) for the specification of properties. Until now, PLCverif depended on third-party tools that accept LTL specifications to perform verification. However, our experience with industrial PLC programs shows that, to overcome analysis limitations, a wide range of techniques are needed to successfully verify complex properties. In this paper, we extend PLCverif to enable PLC program verification of pure-past LTL (PLTL) safety properties with assertion-based verification tools. To this end, we take an algorithm from the runtime-monitoring domain, apply it to bounded model checking of PLC programs, and implement it in PLCverif. We extend the integration of NASA’s Formal Requirements Elicitation Tool (FRET) into PLCverif to use PLTL properties generated with FRET. In addition, we leverage the program structure induced by the PLC scan-cycle for a state-space reduction. Finally, we expose the algorithm to a real-world case study of critical systems at CERN.

Formal verification↗
NASA NTRS1998

Baseline Observations of Hemispheric Sea Ice with the Nimbus 7 Scanning Multichannel Microwave Radiometer

The Scanning Multichannel Microwave Radiometer (SMMR) on board the NASA Nimbus 7 satellite was designed to obtain data for sea surface temperatures (SSTs), near-surface wind speeds, sea ice coverage and type, rainfall rates over the oceans, cloud water content, snow water equivalent, and soil moisture. In this paper, I shall emphasize the sea ice observations and mention briefly some important SST observations. A prime factor contributing to the importance of SMMR sea ice observations lies in their successful integration into a long-term time series, presently being extended by observations from the series of Special Sensor Microwave/Imager (SSMI) on board the DOD/DMSP F8, Fl1, and F12 satellites. This currently constitutes a 19-year data set. Almost half of this was provided by the SMMR. Unfortunately, the 4-year data set produced earlier by the single-channel Electrically Scanned Microwave Radiometer (ESMR) was not successfully integrated into the SMMR/SSMI data set. This resulted primarily from the lack of an overlap period to provide intersensor adjustment, but also because of the large difference between the algorithms to produce ice concentrations and large temporal gaps in the ESMR data. The lack of overlap between the SeaSat and Nimbus 7 SMMR data sets was an important consideration for also excluding the SeatSat one, but the spatial gaps especially in the Southern Hemisphere daily SeaSat observations was another. The sea ice observations will continue into the future by means of the Advanced Microwave Scanning Radiometer (AMSR) on board the ADEOS II and EOS satellites due to be launched in mid- and late-2000, respectively. Analysis of the sea ice data has been carried out by a number of different techniques. Long-term trends have been examined by means of ordinary least squares and band-limited regression. Oscillations in the data have been examined by band-limited Fourier analysis. Here, I shall present results from a novel combination of Principal Component analysis and the recently-developed Empirical Mode Decomposition (EMD). In this method, the data are first separated into spatial and temporal parts, and then the temporal parts of the first few PCs are broken into intrinsic modes by the EMD method.

Gloersen, Per↗