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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Efficient and Safe Hydrogen Refueling of Fuel Cell Vehicles from an Emergency Chemical Hydride Storage Source

Zero-emissions hydrogen fuel cell electrical vehicles (FCEVs) have become more popular in recent years. However, the limited availability of hydrogen fueling stations is considered a critical barrier to sustainable adoption of hydrogen FCEV. To enable the widespread deployment and commercialization of hydrogen FCEV, the availability of hydrogen refueling stations needs to improve. One of the consequences of the lack of hydrogen refueling infrastructure is that consumers can suffer from “range anxiety”, meaning consumers would get anxious of running out of fuel during long-distance trip [4]. A practical solution is to provide a compact emergency hydrogen refueler that can be used if the consumer runs out of hydrogen before reaching the nearest hydrogen refueling station. A safe, compact, and user-friendly hydrogen refueler would give consumers the flexibility they need to feel comfortable using their hydrogen FCEV when planning a long-distance trip. Offering this product would alleviate range anxiety, and it would make Hydrogen FCEV a more attractive alternative to gasoline vehicles. The emergency hydrogen refueler consists of a lithium hydride bed that reacts with liquid water to produce hydrogen gas and lithium hydroxide.

08 HYDROGEN↗
DOE OSTI2021

AI to Predict Glass Compositions Satisfying Property and Cooling Rate Criteria

This project aimed to develop a predictive, artificial intelligence/machine learning-based model to identify glass compositions satisfying specified property requirements. Such a model would provide a systematic approach for narrowing down the nearly infinite range of possible compositions for glasses and minimize unnecessary experimental trial and error. A large empirical data set for training and testing the algorithm was obtained from the SciGlass database. It contains glass compositions and corresponding property data from a wide range of literature sources. However, the currently available form of this data, recently released under an open database license, is not conducive to easy querying and use. The data structure was deciphered and a customized parsing code developed to make this data more usable for the current and future work. Neural network models were developed and trained on viscosity data from the database and demonstrated potential for improving prediction accuracy over a traditional regression model.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1973

The International Planetary Patrol Program - An assessment of the first three years.

Day-to-day and hour-to-hour changes in the large-scale atmospheric and surface features of the planets can now be studied more effectively than previously possible. Since 1969 a network of observatories has obtained almost uninterrupted photographic coverage during all apparitions of Jupiter and Mars, plus some of Venus. Patrol films and catalogs are available to the scientific community. Recent or current analyses include the distribution and motion of clouds on Mars, the development and decay of Martian dust storms, the seasonal, diurnal, and random fluctuations in contrast between adjacent light and dark regions on Mars, the detection of vertical shear in the Jovian atmosphere, the longitudinal oscillation of the Red Spot, the dependence of rotation period on xenographic latitude and on time, the eruption and spread of south equatorial belt disturbances, and the retrograde circulation of the Venus cloud deck.

Baum, W. A.↗
NASA NTRS1978

NASTRAN analysis of a wheel-rail loading on its foundation

One type of azimuth bearing for a large ground antenna (100 m) will consist of steel wheels, mounted at four corners of the alidade, rolling on a circular flat rail which provides the vertical restraints; a radial constraining bearing at the center of the alidade provides the horizontal restraints. One important design feature is the compressive stresses in the grout or concrete foundation under the wheel-rail load. A finite element analysis check was made of a particular design that consists of a steel rail resting on a concrete foundation. Symmetry was assumed as much as possible in order to minimize the models, but meaningful element sizes were used. Recently developed isoparametric hexahedron elements available in the NASTRAN computing program, which minimizes the number of elements required while maintaining the accuracy of the computed stresses, were used with two versions of NASTRAN. Test cases to check with the analytical solutions were made. A side loading was also applied to calculate the increase in the concrete stresses.

Katow, M. S.↗
NASA NTRS1983

Fundamental processes in pair plasmas

The various processes that produce and destroy electron-positron pairs are reviewed, and the timescales of these processes are compared to thermalization, accretion, and cooling timescales. The various radiation spectra produced by relativistic, thermal plasmas are considered. Recent results for the equilibria available to finite, thermal relativistic plasmas with and without embedded magnetic fields are reviewed. Such plasmas, in steady state, have maximum temperatures, luminosities, and field strengths, useful diagnostics for interpreting quasars and active galaxies.

Lightman, A. P.↗
NASA NTRS1984

High spectral resolution remote sensing of the land

Spectral remote sensing has been practiced on a large scale since the launch of Landsat 1 in 1972. The limited information contained in this spectrally undersampled data set has led to the development of sophisticated statistical-inferential methods for data analysis. The results are usually limited by the availability of ground truth information. Recent technological developments have made it feasible to create narrow-band, contiguous, spectral image data sets that make possible the identification of surface cover materials based on the complete reflectance spectrum for each picture element. This capability will revolutionize the use of remote sensing data and require new deterministic image processing techniques to extract the full information content from the data. Sensors, based on the concept of imaging spectrometry and the new technology of area array infrared detectors, have been constructed and are candidates for Shuttle and space platform flights.

Goetz, A. F. H.↗
NASA NTRS1987

Applications of computational modeling in ballistics

The development of the technology of ballistics as applied to gun launched Army weapon systems is the main objective of research at the U.S. Army Ballistic Research Laboratory (BRL). The primary research programs at the BRL consist of three major ballistic disciplines: exterior, interior, and terminal. The work done at the BRL in these areas was traditionally highly dependent on experimental testing. A considerable emphasis was placed on the development of computational modeling to augment the experimental testing in the development cycle; however, the impact of the computational modeling to this date is modest. With the availability of supercomputer computational resources recently installed at the BRL, a new emphasis on the application of computational modeling to ballistics technology is taking place. The major application areas are outlined which are receiving considerable attention at the BRL at present and to indicate the modeling approaches involved. An attempt was made to give some information as to the degree of success achieved and indicate the areas of greatest need.

Sturek, Walter B.↗
NASA NTRS1991

Big bang nucleosynthesis - The standard model and alternatives

The standard homogeneous-isotropic calculation of the big bang cosmological model is reviewed, and alternate models are discussed. The standard model is shown to agree with the light element abundances for He-4, H-2, He-3, and Li-7 that are available. Improved observational data from recent LEP collider and SLC results are discussed. The data agree with the standard model in terms of the number of neutrinos, and provide improved information regarding neutron lifetimes. Alternate models are reviewed which describe different scenarios for decaying matter or quark-hadron induced inhomogeneities. The baryonic density relative to the critical density in the alternate models is similar to that of the standard model when they are made to fit the abundances. This reinforces the conclusion that the baryonic density relative to critical density is about 0.06, and also reinforces the need for both nonbaryonic dark matter and dark baryonic matter.

Schramm, David N.↗
NASA NTRS1992

Detection of x ray sources in PROS

The problem of detecting discrete sources in x-ray images has much in common with the problem of automatic source detection at other wavelengths. In all cases, one searches for positive brightness enhancements exceeding a certain threshold, which appear consistent with what one expects for a point source, in the presence of a (possibly) spatially variable background. Multidimensional point spread functions (e.g., dependent on detector position and photon energy) are also common. At the same time, the problem in x-ray astronomy has some unique aspects. For example, for typical x-ray exposures in current or recent observatories, the number of available pixels far exceeds the number of actual x-ray events, so Poisson, rather than Gaussian statistics apply. Further, extended cosmic x-ray sources are common, and one often desires to detect point sources in the vicinity or even within bright, diffuse x-ray emission. Finally, support structures in x-ray detectors often cast sharp shadows in x-ray images making it necessary to detect sources in a region of rapidly varying exposure. We have developed a source detection package within the IRAF/PROS environment which attempts to deal with some of the problems of x-ray source detection. We have patterned our package after the successful Einstein Observatory x-ray source detection programs. However, we have attempted to improve the flexibility and accessibility of the functions and to provide a graphical front-end for the user. Our philosophy has been to use standard IRAF tasks whenever possible for image manipulation and to separate general functions from mission-specific ones. We will report on the current status of the package and discuss future developments, including simulation tasks, to allow the user to assess detection efficiency and source significance, tasks to determine source intensity, and alternative detection algorithms.

Deponte, J.↗
NASA NTRS1994

The design and development of signal-processing algorithms for an airborne x-band Doppler weather radar

Improved measurements of precipitation will aid our understanding of the role of latent heating on global circulations. Spaceborne meteorological sensors such as the planned precipitation radar and microwave radiometers on the Tropical Rainfall Measurement Mission (TRMM) provide for the first time a comprehensive means of making these global measurements. Pre-TRMM activities include development of precipitation algorithms using existing satellite data, computer simulations, and measurements from limited aircraft campaigns. Since the TRMM radar will be the first spaceborne precipitation radar, there is limited experience with such measurements, and only recently have airborne radars become available that can attempt to address the issue of the limitations of a spaceborne radar. There are many questions regarding how much attenuation occurs in various cloud types and the effect of cloud vertical motions on the estimation of precipitation rates. The EDOP program being developed by NASA GSFC will provide data useful for testing both rain-retrieval algorithms and the importance of vertical motions on the rain measurements. The purpose of this report is to describe the design and development of real-time embedded parallel algorithms used by EDOP to extract reflectivity and Doppler products (velocity, spectrum width, and signal-to-noise ratio) as the first step in the aforementioned goals.

Nicholson, Shaun R.↗
NASA NTRS1995

The Evolution of Mission Architectures for Human Lunar Exploration

Defining transportation architectures for the human exploration of the Moon is a complex task due to the multitude of mission scenarios available. The mission transportation architecture recently proposed for the First Lunar Outpost (FLO) was not designed from carefully predetermined mission requirements and goals, but evolved from an initial set of requirements, which were continually modified as studies revealed that some early assumptions were not optimal. This paper focuses on the mission architectures proposed for FLO and investigates how these transportation architectures evolved. A comparison of the strengths and weaknesses of the three distinct mission architectures are discussed, namely (1) Lunar Orbit Rendezvous, (2) staging from the Cislunar Libration Point, and (3) direct to the lunar surface. In addition, several new and revolutionary architectures are discussed.

Everett, S. F.↗
NASA NTRS1999

A Methodology for Writing High Quality Requirement Specifications and for Evaluating Existing Ones

Requirements development and management have always been critical in the implementation of software systems-engineers are unable to build what analysts can not define. It is generally accepted that the earlier in the life cycle potential risks are identified the easier it is to eliminate or manage the conditions that introduce that risk. Problems that are not found until testing are approximately 14 times more costly to fix than if the problem was found in the requirement phase. The requirements specification, as the first tangible representation of the capability to be produced, establishes the basis for all of the project's engineering management and assurance functions. If the quality of the requirements specification is poor it can give rise to risks in all areas of the project. Recently, automated tools have become available to support requirements management. The use of these tools not only provides support in the definition and tracing of requirements, but it also opens the door to effective use of metrics in characterizing and assessing the quality of the requirement specifications.

Rosenberg, Linda↗
NASA NTRS1998

Testing, Requirements, and Metrics

The criticality of correct, complete, testable requirements is a fundamental tenet of software engineering. Also critical is complete requirements based testing of the final product. Modern tools for managing requirements allow new metrics to be used in support of both of these critical processes. Using these tools, potential problems with the quality of the requirements and the test plan can be identified early in the life cycle. Some of these quality factors include: ambiguous or incomplete requirements, poorly designed requirements databases, excessive or insufficient test cases, and incomplete linkage of tests to requirements. This paper discusses how metrics can be used to evaluate the quality of the requirements and test to avoid problems later. Requirements management and requirements based testing have always been critical in the implementation of high quality software systems. Recently, automated tools have become available to support requirements management. At NASA's Goddard Space Flight Center (GSFC), automated requirements management tools are being used on several large projects. The use of these tools opens the door to innovative uses of metrics in characterizing test plan quality and assessing overall testing risks. In support of these projects, the Software Assurance Technology Center (SATC) is working to develop and apply a metrics program that utilizes the information now available through the application of requirements management tools. Metrics based on this information provides real-time insight into the testing of requirements and these metrics assist the Project Quality Office in its testing oversight role. This paper discusses three facets of the SATC's efforts to evaluate the quality of the requirements and test plan early in the life cycle, thus preventing costly errors and time delays later.

Rosenberg, Linda↗
NASA NTRS1999

A Methodology for Writing High Quality Requirements Specification and Evaluating Existing Ones

Requirements development and management have always been critical in the implementation of software systems; engineers are unable to build what analysts can't define. It is generally accepted that the earlier in the life cycle potential risks are identified the easier it is to eliminate or manage the conditions that introduce that risk. Problems that are not found until testing are approximately 14 times more costly to fix than if the problem was found in the requirement phase. The requirements specification, as the first tangible representation of the capability to be produced, establishes the basis for all of the project's engineering management and assurance functions. If the quality of the requirements specification is poor it can give rise to risks in all areas of the project. Recently, automated tools have become available to support requirements management. The use of these tools not only provides support in the definition and tracing of requirements, but it also opens the door to effective use of metrics in characterizing and assessing the quality of the requirement specifications.

Rosenberg, Linda↗
NASA NTRS1998

A Review of the New AVIRIS Data Processing System

The processing of AVIRIS data - from the Metrum Very Large Data Store (VLDS) flight tape to delivered data products - has traditionally been performed in essentially the same way, from the beginning of the AVIRIS project up to and including the 1996 flight season. Starting with the 1997 flight season, a drastically different paradigm has been used for the processing of AVIRIS data. This change was made possible by the recent development of and related availability of affordable data storage devices.

Aronsson, Mikael↗
NASA NTRS1995

Aerothermal Performance Envelopes for Hypersonic Small Radius Unswept Leading Edges and Nosetips

Small radius leading edges and nosetips were utilized to minimize wave drag in early hypersonic vehicle concepts until further analysis demonstrated that extreme aerothermodynamic heating would cause severe ablation or blunting of the available thermal protection system materials. Recent studies indicate that diboride composite materials are shape stable under extreme aerothermodynamic heating at ultra high temperatures. Aerothermal performance envelopes for sharp components made from these materials are presented in this work to demonstrate the effects of convective blocking, surface catalycity, surface emissivity, and rarefied flow effects on steady state operation at altitudes from sea level to 90 km. These components are capable of steady state operation at velocities up to 7.9 km/s at altitudes near 90 km.

Kolodziej, Paul↗
NASA NTRS2003

Automated Modeling and Simulation Using the Bond Graph Method for the Aerospace Industry

Bond graph modeling was originally developed in the late 1950s by the late Prof. Henry M. Paynter of M.I.T. Prof. Paynter acted well before his time as the main advantage of his creation, other than the modeling insight that it provides and the ability of effectively dealing with Mechatronics, came into fruition only with the recent advent of modern computer technology and the tools derived as a result of it, including symbolic manipulation, MATLAB, and SIMULINK and the Computer Aided Modeling Program (CAMPG). Thus, only recently have these tools been available allowing one to fully utilize the advantages that the bond graph method has to offer. The purpose of this paper is to help fill the knowledge void concerning its use of bond graphs in the aerospace industry. The paper first presents simple examples to serve as a tutorial on bond graphs for those not familiar with the technique. The reader is given the basic understanding needed to appreciate the applications that follow. After that, several aerospace applications are developed such as modeling of an arresting system for aircraft carrier landings, suspension models used for landing gears and multibody dynamics. The paper presents also an update on NASA's progress in modeling the International Space Station (ISS) using bond graph techniques, and an advanced actuation system utilizing shape memory alloys. The later covers the Mechatronics advantages of the bond graph method, applications that simultaneously involves mechanical, hydraulic, thermal, and electrical subsystem modeling.

Granda, Jose J.↗
NASA NTRS2005

The Need for Fusion Propulsion

Fusion propulsion is inevitable if the human race remains dedicated to exploration of the solar system. There are fundamental reasons why fusion surpasses more traditional approaches to routine crewed missions to Mars, crewed missions to the outer planets, and deep space high speed robotic missions, assuming that reduced trip times, increased payloads, and higher available power are desired. A recent series of informal discussions were held among members from government, academia, and industry concerning fusion propulsion. We compiled a sufficient set of arguments for utilizing fusion in space. If the U.S. is to lead the effort and produce a working system in a reasonable amount of time, NASA must take the initiative, relying on, but not waiting for, DOE guidance. In this talk those arguments for fusion propulsion are presented, along with fusion enabled mission examples, fusion technology trade space, and a proposed outline for future efforts.

Cassibry, Jason↗