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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 1,639 records · Page 91
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Field Programmable Gate Array-Based Reactor Protection Systems and Potential for Inclusion of Secure Elements to Improve Cybersecurity

For acceptable implementations of technologies like wireless communications, remote monitoring, etc., strong mitigations must be developed and evaluated to ensure that new attack pathways do not increase risk for Advanced Reactors. Secure Elements can be adopted and adapted for this purpose based on tamper resistance and cryptographic abilities, but research must be done to properly integrate into critical components such as FPGA-based Important to Safety systems in conjunction with current and future regulations on cyber security features in Advanced Reactors. Typically, the integration of a Secure Element happens during the POST and UEFI boot of a computing platform, performed by the Operating System, which is not possible with FPGAs because they do not include these firmware components. Work must be done to identify a reliable and secure method for integration in FPGA-based systems which lack Operating Systems and therefore complex boot procedures, system calls, etc.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

RCSB Protein Data Bank: visualizing groups of experimentally determined PDB structures alongside computed structure models of proteins

Recent advances in Artificial Intelligence and Machine Learning (e.g., AlphaFold, RosettaFold, and ESMFold) enable prediction of three-dimensional (3D) protein structures from amino acid sequences alone at accuracies comparable to lower-resolution experimental methods. These tools have been employed to predict structures across entire proteomes and the results of large-scale metagenomic sequence studies, yielding an exponential increase in available biomolecular 3D structural information. Given the enormous volume of this newly computed biostructure data, there is an urgent need for robust tools to manage, search, cluster, and visualize large collections of structures. Equally important is the capability to efficiently summarize and visualize metadata, biological/biochemical annotations, and structural features, particularly when working with vast numbers of protein structures of both experimental origin from the Protein Data Bank (PDB) and computationally-predicted models. Moreover, researchers require advanced visualization techniques that support interactive exploration of multiple sequences and structural alignments. This paper introduces a suite of tools provided on the RCSB PDB research-focused web portal RCSB. org, tailor-made for efficient management, search, organization, and visualization of this burgeoning corpus of 3D macromolecular structure data.

3D visualization↗
NASA NTRS1972

Imaging experiment - The Viking Lander.

The Viking Lander Imaging System will consist of two identical facsimile cameras. Each camera has a high-resolution mode with an instantaneous field of view of 0.04 deg, and survey and color modes with instantaneous fields of view of 0.12 deg. Cameras are positioned one meter apart to provide stereoscopic coverage of the near-field. The Imaging Experiment will provide important information about the morphology, composition, and origin of the Martian surface and atmospheric features. In addition, lander pictures will provide supporting information for other experiments in biology, organic chemistry, meteorology, and physical properties.

Mutch, T. A.↗
NASA NTRS1976

Cosmic X-ray observations with OSO-8

The GSFC Cosmic X-ray Spectroscopy experiment aboard OSO-8 has operated successfully since launch providing spectral and temporal data on X-ray sources in tha energy range 2-60 keV. Analysis of quick look data shows a variety of spectral features, some stable, others variable, which will increase understanding of the nature of individual sources. In particular, observed emission and absorption features that can be attributed to iron will result in abundance measures of this important element in sources such as some X-ray binaries, the supernova remnant Cas A, and the nucleus of the galaxy Cen A.

Serlemitsos, P. J.↗
NASA NTRS1977

An empirical study of scanner system parameters

Parametric values (instantaneous field of view, number and location of spectral bands, signal-to-noise ratio, etc.) of a multispectral scanner (thematic mapper) are assigned empirically. An empirical simulation approach was used with candidate parameter values selected by heuristic means. Results obtained using a conventional maximum likelihood pixel classifier suggest that although the classification accuracy declines slightly as the instantaneous field of view (IFOV) is decreased this is more than made up by an improved mensuration accuracy. Use of a classifier involving both spatial and spectral features helps resist degradation as the signal-to-noise ratio is decreased. The importance of having at least one spectral band in each of the major available portions of the optical spectrum is demonstrated.

Landgrebe, D. A.↗
NASA NTRS1978

Observations of the 51.8 micron forbidden O III emission line in Orion

This letter reports observations of the 51.8-micron fine-structure transition p2: 3P(2) - 3P(1) for doubly ionized oxygen. The observed line strength in the Orion Nebula is (5 + or - 3) by 10 to the -15th power W/sq cm, in good agreement with the theoretical predictions of Simpson (1975). The observations are also consistent with the predicted line position, 51.8 microns. The line lies close to an atmospheric water-vapor feature at 51.7 microns but is sufficiently distant so that corrections for this feature are straightforward. Observations of the 51.8-micron forbidden O III line are particularly important, since the previously discovered 88-micron line from the same ion also is strong. This pair of lines should therefore yield new data about densities in observed H II regions; or else, if density data already are available from radio or other observations, the lines can be used to determine the differential dust absorption between 52 and 88 microns in front of heavily obscured regions.

Melnick, G.↗
NASA NTRS1981

Guy cable design and damping for vertical axis wind turbines

Guy cables are frequently used to support vertical axis wind turbines since guying the turbine reduces some of the structural requirements on the tower. The guys must be designed to provide both the required strength and the required stiffness at the top of the turbine. The axial load which the guys apply to the tower, bearings, and foundations is an undesirable consequence of using guys to support the turbine. Limiting the axial load so that it does not significantly affect the cost of the turbine is an important objective of the cable design. The lateral vibrations of the cables is another feature of the cable design which needs to be considered. These aspects of the cable design are discussed, and a technique for damping cable vibrations was mathematically analyzed and demonstrated with experimental data.

Carne, T. G.↗
NASA NTRS1983

A high strength, torsionally rigid, deployable and retractable mast for space applications

A structural mast was developed which during and after full deployment produces a supporting structure with the characteristics of a high bending moment capability, high stiffness and, particularly important for instrument deployment, a high degree of position repeatability and torsional rigidity. These features were accomplished while providing and easily retractable mast with a high life cycle capability. Since these properties are consistent throughout the full range of deployed lengths, partial deployments or retractions can be utilized for checkout, balance, fine tuning or whatever other reason may be deemed necessary for operation modes or spacecraft stability.

Dibiasi, L.↗
NASA NTRS1983

High-speed digital signal normalization for feature identification

A design approach for high speed normalization of digital signals was developed. A reciprocal look up table technique is employed, where a digital value is mapped to its reciprocal via a high speed memory. This reciprocal is then multiplied with an input signal to obtain the normalized result. Normalization improves considerably the accuracy of certain feature identification algorithms. By using the concept of pipelining the multispectral sensor data processing rate is limited only by the speed of the multiplier. The breadboard system was found to operate at an execution rate of five million normalizations per second. This design features high precision, a reduced hardware complexity, high flexibility, and expandability which are very important considerations for spaceborne applications. It also accomplishes a high speed normalization rate essential for real time data processing.

Ortiz, J. A.↗
NASA NTRS1984

SeaMARC 2 side-scan images of submarine volcanoes: Potential analogues for Venus

The Earth's surface beneath the oceans may be very similar, in terms of ambient pressures, to the surface of Venus. For that reason it is particularly important for geologists studying the surface of Venus to understand the processes which form features on the floors of the oceans. With the SeaMARC 2 seafloor mapping system, it is possible to view a swath of seafloor that is 10 km wide (about 6.2 mi). Side scan images of the Mariana region show that volcanoes of the island arc are more complicated than previously realized and that features of the fore-arc region, which resemble volcanoes morphologically, may result from processes other than volcanism. By comparing data obtained from the ocean floor with radar images of Venus, the geological evolution of that planet may be more fully understood.

Fryer, P.↗
NASA NTRS1987

Singular perturbations and time scales (SPaTS) in discrete control systems-An overview

Recent developments in the theory of singular perturbations and time scales (SPaTS) in discrete control systems are reviewed. Sources of discrete models and the effect of the discretizing interval on the model are examined. The analysis of two-time scale systems is presented to bring out typical characteristic features of SPaTS. In the control of the two-time scale systems, the important issue of multirate sampling is addressed.

Naidu, D. S.↗
NASA NTRS1989

Transonic propulsion system integration analysis at McDonnell Aircraft Company

The technology of Computational Fluid Dynamics (CFD) is becoming an important tool in the development of aircraft propulsion systems. Two of the most valuable features of CFD are: (1) quick acquisition of flow field data; and (2) complete description of flow fields, allowing detailed investigation of interactions. Current analysis methods complement wind tunnel testing in several ways. Herein, the discussion is focused on CFD methods. However, aircraft design studies need data from both CFD and wind tunnel testing. Each approach complements the other.

Cosner, Raymond R.↗
NASA NTRS1991

NDE of advanced turbine engine components and materials by computed tomography

Computed tomography (CT) is an X-ray technique that provides quantitative 3D density information of materials and components and can accurately detail spatial distributions of cracks, voids, and density variations. CT scans of ceramic materials, composites, and engine components were taken and the resulting images will be discussed. Scans were taken with two CT systems with different spatial resolution capabilities. The scans showed internal damage, density variations, and geometrical arrangement of various features in the materials and components. It was concluded that CT can play an important role in the characterization of advanced turbine engine materials and components. Future applications of this technology will be outlined.

Yancey, R. N.↗
NASA NTRS1993

Boundary-layer transition extent measurements on a cone and flat plate at Mach 3.5

Wide excursions of the boundary-layer transition region are expected to occur on the X-30 National Aerospace Plane (NASP) due to the high Mach number, high temperature, and low density environment experienced during flight. Undesirable features of the transition region, such as the peak heat transfer rate, make it important to understand transition region physics. The current study investigates transition extent in 2D and axisymmetric bounday-layer flows. Surface-pitot and recovery temperature data obtained on a cone and flat plate at Mach 3.5 in the Supersonic Low-Disturbance Pilot Tunnel at NASA Langley are presented. Results show the effects of the unit Reynolds number, freestream disturbances, and nose/leading-edge bluntness on the extent of transition.

Chen, Fang-Jenq↗
NASA NTRS1993

C/O atomic ratios in micrometer-size crushed grains from Antarctic micrometeorites and two carbonaceous meteorites

Antarctic micrometeorites (AMM's) have similarities (but also differences) with primitive meteorites, such as unequilibrated mineral assemblages. To further assess such similarities, we have measured the carbon content of micrometeorites and meteorites (Orgueil and Murchison), as determined in a random selection of micrometer-size crushed grain, with an analytical transmission electron microscope. Such analyses yield the C/O atomic ratio, the major and minor elements contents, and the textural features of the grains on a scale of approx. equal to 100 nanometers. An important proportion of micrometeorites from both the 100-400 micron and the 50-100 micron size fractions contains much more carbon than CI chondrite Orgueil. The average C-content of all micrometeorites in these two size fractions amount to approximately 1.8 x CI, and approximately 0.8 x CI, respectively (CI refers to the bulk C-content of Orgueil, of about 3.5 percent by weight). Carbon is usually not homogeneously distributed in the micrometeorite but is concentrated in C-rich grains. So far, most of these grains are amorphous, and seem to be associated with an oxidized Fe-rich phase (possibly a variety of 'dirty' magnetite). About 5 percent of them have the composition of 'COPS', a phase additionally enriched in O, P, and S.

Perreau, M.↗
NASA NTRS2007

Testing Special Relativity at High Energies with Astrophysical Sources

Since the group of Lorentz boosts is unbounded, there is a question as to whether Lorentz invariance (LI) holds to infinitely short distances. However, special and general relativity may break down at the Planck scale. Various quantum gravity scenarios such as loop quantum gravity, as well as some forms of string theory and extra dimension models may imply Lorentz violation (LV) at ultrahigh energies. The Gamma-Ray Large Area Space Telescope (GLAST), to be launched in mid-December, will measure the spectra of distant extragalactic sources of high energy gamma-rays, particularly active galactic nuclei and gamma-ray bursts. GLAST can look for energy-dependent gamma-ray propagation effects from such sources as a signal of Lorentz invariance violation. These sources may also exhibit the high energy cutoffs predicted to be the result of intergalactic annihilation interactions with low energy photons having a flux level as determined by various astronomical observations. With LV the threshold for such interactions can be significantly raised, changing the predicted absorption turnover in the observed spectrum of the sources. Stecker and Glashow have shown that the existence such absorption features in the spectra of extragalactic sources puts constraints on LV. Such constraints have important implications for some quantum gravity and large extra dimension models. Future spaceborne detectors dedicated to measuring gamma-ray polarization can look for birefringence effects as a possible signal of loop quantum gravity. A very small LV may also result in the modification or elimination of the GZK effect, thus modifying the spectrum of ultrahigh energy cosmic rays. This possibility can be explored with ground-based arrays such as Auger or with a space based detector system such as the proposed OWL satellite mission.

Stecker, F. W.↗
NASA NTRS2008

SPICE Module for the Satellite Orbit Analysis Program (SOAP)

A SPICE module for the Satellite Orbit Analysis Program (SOAP) precisely represents complex motion and maneuvers in an interactive, 3D animated environment with support for user-defined quantitative outputs. (SPICE stands for Spacecraft, Planet, Instrument, Camera-matrix, and Events). This module enables the SOAP software to exploit NASA mission ephemeris represented in the JPL Ancillary Information Facility (NAIF) SPICE formats. Ephemeris types supported include position, velocity, and orientation for spacecraft and planetary bodies including the Sun, planets, natural satellites, comets, and asteroids. Entire missions can now be imported into SOAP for 3D visualization, playback, and analysis. The SOAP analysis and display features can now leverage detailed mission files to offer the analyst both a numerically correct and aesthetically pleasing combination of results that can be varied to study many hypothetical scenarios. The software provides a modeling and simulation environment that can encompass a broad variety of problems using orbital prediction. For example, ground coverage analysis, communications analysis, power and thermal analysis, and 3D visualization that provide the user with insight into complex geometric relations are included. The SOAP SPICE module allows distributed science and engineering teams to share common mission models of known pedigree, which greatly reduces duplication of effort and the potential for error. The use of the software spans all phases of the space system lifecycle, from the study of future concepts to operations and anomaly analysis. It allows SOAP software to correctly position and orient all of the principal bodies of the Solar System within a single simulation session along with multiple spacecraft trajectories and the orientation of mission payloads. In addition to the 3D visualization, the user can define numeric variables and x-y plots to quantitatively assess metrics of interest.

Coggi, John↗
NASA NTRS2012

Comparative Study of Aerosol and Cloud Detected by CALIPSO and OMI

The Ozone Monitoring Instrument (OMI) on the Aura Satellite detects the presence of desert dust and smoke particles (also known as aerosols) in terms of a parameter known as the UV Aerosol Index (UV AI). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission measures the vertical distribution of aerosols and clouds. Aerosols and clouds play important roles in the atmosphere and climate system. Accurately detecting their presence, altitude, and properties using satellite radiance measurements is a very important task. This paper presents a comparative analysis of the CALIPSO Version 2 Vertical Feature Mask (VFM) product with the (OMI) UV Aerosol Index (UV AI) and reflectivity datasets for a full year of 2007. The comparison is done at regional and global scales. Based on CALIPSO arid OMI observations, the vertical and horizontal extent of clouds and aerosols are determined and the effects of aerosol type selection, load, cloud fraction on aerosol identification are discussed. It was found that the spatial-temporal correlation found between CALIPSO and OMI observations, is strongly dependent on aerosol types and cloud contamination. CALIPSO is more sensitivity to cloud and often misidentifies desert dust aerosols as cloud, while some small scale aerosol layers as well as some pollution aerosols are unidentified by OMI UV AI. Large differences in aerosol distribution patterns between CALIPSO and OMI are observed, especially for the smoke and pollution aerosol dominated areas. In addition, the results found a significant correlation between CALIPSO lidar 1064 nm backscatter and the OMI UV AI over the study regions.

Chen, Zhong↗