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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

An aperture synthesis study of Saturn and its rings at 3.71-cm wavelength

Aperture synthesis maps of Saturn and its ring system are presented. The maps are free from most of the assumptions about the brightness structure of Saturn that were used in a previous model-fitting analysis. Generally, the maps confirm the model-fitting results, with the exception that the brightness temperature of the planet determined by the models is greater than it needs to be in order to match the contours in the map. This discrepancy is attributed to random errors in the phase of the visibility function.

Schloerb, F. P.↗
NASA NTRS1981

Flow fields within Jupiter's Great Red Spot and White Oval BC

Voyager 1 high-resolution images of Jupiter's Great Red Spot (GRS) and White Oval BC are used to map flow fields within these two areas. The relative vorticity is computed as a function of semi-major axis length and position angle in a coordinate system consisting of concentric ellipses of equal eccentricity. Wind speeds of 110-120 m/s are observed near the outer edge of both features, and along their minor axes relative vorticity profiles reach a maximum of 0.00006/s. Maximum Rossby numbers of 0.36 are computed for flows within both features, and are found to be low, indicating geostrophic constraints on the flow. The difference in streamline curvature within the GRS and the Oval BC is found to compensate for the difference in planetary vorticity at the respective latitudes of the features. Finally, motions within the central region of the GRS are slower and more random than around the spot's outer portion.

Mitchell, J. L.↗
NASA NTRS1984

Theoretical aspects of photoclinometric terrain profiling on the Galilean satellites

For large parts of the surfaces of the Galilean satellites there is no stereoscopic high resolution imagery, and so for shadow-free regions far from the terminator, the only method of obtaining topograpic information is photoclinometry, the technique of converting brightness variations into local surface tilts and hence into topographic profiles and contour maps. The conversion from brightness changes to slopes require knowledge of the angular photometric function for the type of planetary surface terrain being analyzed, i.e., the relationship describing the brightness of the surface as a function of the angles of incidence (I) and emergence (E) of light at a surface element. In order to investigate the effects of these changes on the shapes of topographic profiles deduced from the functions, an area of grooved terrain (lines 500-505, samples 550-650 on frame 20640.27 0060J2) using wide ranges of values of all the adjustable parameters in Hapke's new photometric function were analyzed.

Wilson, L.↗
NASA NTRS1991

Program Generates Images Of Solid Surfaces

Solid Surface Modeler (SSM) computer program generates three-dimensional computer models of solid surfaces for use in visual analysis and animation. Provides advanced functions, including Constructive Solid Geometry, Skin Construction, Tube Construction, Material Property Editing, and Texture Map Tools. Allows user to change such attributes as color, reflectivity, smoothing, and position of object easily. Model saved in ASCII or binary format for use in another program or saved in edit format for reloading in SSM. Written in standard C.

Goza, Sharon P.↗
NASA NTRS1989

Large liquid rocket engine transient performance simulation system

Phase 1 of the Rocket Engine Transient Simulation (ROCETS) program consists of seven technical tasks: architecture; system requirements; component and submodel requirements; submodel implementation; component implementation; submodel testing and verification; and subsystem testing and verification. These tasks were completed. Phase 2 of ROCETS consists of two technical tasks: Technology Test Bed Engine (TTBE) model data generation; and system testing verification. During this period specific coding of the system processors was begun and the engineering representations of Phase 1 were expanded to produce a simple model of the TTBE. As the code was completed, some minor modifications to the system architecture centering on the global variable common, GLOBVAR, were necessary to increase processor efficiency. The engineering modules completed during Phase 2 are listed: INJTOO - main injector; MCHBOO - main chamber; NOZLOO - nozzle thrust calculations; PBRNOO - preburner; PIPE02 - compressible flow without inertia; PUMPOO - polytropic pump; ROTROO - rotor torque balance/speed derivative; and TURBOO - turbine. Detailed documentation of these modules is in the Appendix. In addition to the engineering modules, several submodules were also completed. These submodules include combustion properties, component performance characteristics (maps), and specific utilities. Specific coding was begun on the system configuration processor. All functions necessary for multiple module operation were completed but the SOLVER implementation is still under development. This system, the Verification Checkout Facility (VCF) allows interactive comparison of module results to store data as well as provides an intermediate checkout of the processor code. After validation using the VCF, the engineering modules and submodules were used to build a simple TTBE.

Mason, J. R.↗
NASA NTRS1990

A deep Abell cluster redshift survey

Redshifts have been measured for a complete sample of 145 Abell clusters of galaxies of median redshift 0.16 covering a 561 sq deg region at high Galactic latitude. Clustering on scales greater than about 70/h Mpc cannot be detected. A large void of diameter about 20,000 km/s seen in maps of the cluster distribution is consistent with smaller scale behavior of the correlation function of the survey. Large-scale peculiar motions are about 1000 km/s or less, a limit inconsistent with the claimed detection by Bahcall et al. (1986) of peculiar motions of about 2000 km/s.

Huchra, John P.↗
NASA NTRS1992

Preliminary separation of galactic and cosmic microwave emission for the COBE Differential Microwave Radiometer

Preliminary models of microwave emission from the Milky Way Galaxy based on COBE and other data are constructed for the purpose of distinguishing cosmic and Galactic signals. Differential Microwave Radiometer (DMR) maps, with the modeled Galactic emission removed, are fitted for a quadrupole distribution. Autocorrelation functions for individual Galactic components are presented. When Galactic emission is removed from the DMR data, the residual fluctuations are virtually unaffected, and therefore they are not dominated by any known Galactic emission component.

Bennet, C. L.↗
NASA NTRS1992

Static assignment of complex stochastic tasks using stochastic majorization

We consider the problem of statically assigning many tasks to a (smaller) system of homogeneous processors, where a task's structure is modeled as a branching process, and all tasks are assumed to have identical behavior. We show how the theory of majorization can be used to obtain a partial order among possible task assignments. Our results show that if the vector of numbers of tasks assigned to each processor under one mapping is majorized by that of another mapping, then the former mapping is better than the latter with respect to a large number of objective functions. In particular, we show how measurements of finishing time, resource utilization, and reliability are all captured by the theory. We also show how the theory may be applied to the problem of partitioning a pool of processors for distribution among parallelizable tasks.

Nicol, David↗
NASA NTRS1993

The distribution of interstellar dust in the solar neighborhood

We surveyed the IRAS data base at the positions of the 1808 O6-B9.5 stars in The Bright Star Catalog for extended objects with excess emission at 60 microns, indicating the presence of interstellar dust at the location of the star. Within 400 pc the filling factor of the interstellar medium, for dust clouds with a density greater than 0.5/cu cm is 14.6 + or - 2.4%. Above a density of 1.0/cu cm, the density distribution function appears to follow a power law index - 1.25. When the dust clouds are mapped onto the galactic plane, the sun appears to be located in a low-density region of the interstellar medium of width about 60 pc extending at least 500 pc in the direction of longitudes 80 deg - 260 deg, a feature we call the 'local trough'.

Gaustad, John E.↗
NASA NTRS2008

Documenting AUTOGEN and APGEN Model Files

A computer program called "autogen hypertext map generator" satisfies a need for documenting and assisting in visualization of, and navigation through, model files used in the AUTOGEN and APGEN software mentioned in the two immediately preceding articles. This program parses autogen script files, autogen model files, PERL scripts, and apgen activity-definition files and produces a hypertext map of the files to aid in the navigation of the model. This program also provides a facility for adding notes and descriptions, beyond what is in the source model represented by the hypertext map. Further, this program provides access to a summary of the model through variable, function, sub routine, activity and resource declarations as well as providing full access to the source model and source code. The use of the tool enables easy access to the declarations and the ability to traverse routines and calls while analyzing the model.

Gladden, Roy E.↗
NASA NTRS2008

Dawn: An Ion-Propelled Journey to the Beginning of the Solar System

The Dawn mission is designed to perform a scientific investigation of the two heaviest mainbelt asteroids Vesta and Ceres. These bodies are believed to preserve records of the physical and chemical conditions present during the formation of the solar system. The mission uses an ion propulsion system to enable the single Dawn spacecraft and its complement of scientific instruments to orbit both of these asteroids. Dawn's three science instruments - the gamma ray and neutron detector, the visible and infrared mapping spectrometer, and the primary framing camera - were successfully tested after launch and are functioning normally. The ion propulsion system includes three ion thrusters of the type flown previously on NASA's Deep Space 1 mission. A minimum of two ion thrusters is necessary to accomplish the Dawn mission. Checkout of two of the ion thrusters was completed as planned within 30 days after launch. This activity confirmed that the spacecraft has two healthy ion thrusters. While further checkout activities are still in progress, the activities completed as of the end of October indicate that the spacecraft is well on its way toward being ready for the start of the thrusting-cruise phase of the mission beginning December 15th.

Vesta↗
NASA NTRS2009

Quantifying Therapeutic and Diagnostic Efficacy in 2D Microvascular Images

VESGEN is a newly automated, user-interactive program that maps and quantifies the effects of vascular therapeutics and regulators on microvascular form and function. VESGEN analyzes two-dimensional, black and white vascular images by measuring important vessel morphology parameters. This software guides the user through each required step of the analysis process via a concise graphical user interface (GUI). Primary applications of the VESGEN code are 2D vascular images acquired as clinical diagnostic images of the human retina and as experimental studies of the effects of vascular regulators and therapeutics on vessel remodeling.

Parsons-Wingerter, Patricia↗
NASA NTRS2007

Robust, Flexible Motion Control for the Mars Explorer Rovers

The Mobility Flight Software, running on computers aboard the Mars Explorer Rover (MER) robotic vehicles Spirit and Opportunity, affords the robustness and flexibility of control to enable safe and effective operation of these vehicles in traversing natural terrain. It can make the vehicles perform specific maneuvers commanded from Earth, and/or can autonomously administer multiple aspects of mobility, including choice of motion, measurement of actual motion, and even selection of targets to be approached. Motion of a vehicle can be commanded by use of multiple layers of control, ranging from motor control at a low level, direct drive operations (e.g., motion along a circular arc, motion along a straight line, or turn in place) at an intermediate level to goal-position driving (that is, driving to a specified location) at a high level. The software can also perform high-level assessment of terrain and selection of safe paths across the terrain: this involves processing of the digital equivalent of a local traversability map generated from images acquired by stereoscopic pairs of cameras aboard the vehicles. Other functions of the software include interacting with the rest of the MER flight software and performing safety checks.

Maimone, Mark↗
NASA NTRS2011

The Plasma Environment at Mercury

Mercury is the least explored terrestrial planet, and the one subjected to the highest flux of solar radiation in the heliosphere. Its highly dynamic, miniature magnetosphere contains ions from the exosphere and solar wind, and at times may allow solar wind ions to directly impact the planet's surface. Together these features create a plasma environment that shares many features with, but is nonetheless very different from, that of Earth. The first in situ measurements of plasma ions in the Mercury space environment were made only recently, by the Fast Imaging Plasma Spectrometer (FIPS) during the MESSENGER spacecraft's three flybys of the planet in 2008-2009 as the probe was en route to insertion into orbit about Mercury earlier this year. Here. we present analysis of flyby and early orbital mission data with novel techniques that address the particular challenges inherent in these measurements. First. spacecraft structures and sensor orientation limit the FIPS field of view and allow only partial sampling of velocity distribution functions. We use a software model of FIPS sampling in velocity space to explore these effects and recover bulk parameters under certain assumptions. Second, the low densities found in the Mercury magnetosphere result in a relatively low signal-to-noise ratio for many ions. To address this issue, we apply a kernel density spread function to guide removal of background counts according to a background-signature probability map. We then assign individual counts to particular ion species with a time-of-flight forward model, taking into account energy losses in the carbon foil and other physical behavior of ions within the instrument. Using these methods, we have derived bulk plasma properties and heavy ion composition and evaluated them in the context of the Mercury magnetosphere.

Raines, James M.↗
NASA NTRS2008

Dawn: an ion-propelled journey to the beginning of the Solar System

The Dawn mission is designed to perform a scientific investigation of the two heaviest mainbelt asteroids Vesta and Ceres. These bodies are believed to preserve records of the physical and chemical conditions present during the formation of the solar system. The mission uses an ion propulsion system to enable the single Dawn spacecraft and its complement of scientific instruments to orbit both of these asteroids. Dawn’s three science instruments – the gamma ray and neutron detector, the visible and infrared mapping spectrometer, and the primary framing camera – were successfully tested after launch and are functioning normally. The ion propulsion system includes three ion thrusters of the type flown previously on NASA’s Deep Space 1 mission. A minimum of two ion thrusters is necessary to accomplish the Dawn mission. Checkout of two of the ion thrusters was completed as planned within 30 days after launch. This activity confirmed that the spacecraft has two healthy ion thrusters. While further checkout activities are still in progress, the activities completed as of the end of October indicate that the spacecraft is well on its way toward being ready for the start of the thrusting-cruise phase of the mission beginning December 15th.

Pavri, Betina↗
DOE OSTI2024

Transportation and Systems Analysis Collaborations in Support of a Federal Consolidated Interim Storage Facility

The U.S. Department of Energy’s Integrated Waste Management (IWM) program under the Office of Nuclear Energy is planning for the future transportation, storage, and eventual disposal of spent nuclear fuel (SNF) and high-level radioactive waste (HLW) from nuclear power plant sites across the United States. To better enable informed decision-making regarding the back end of the nuclear fuel cycle, the IWM program has been sponsoring the development and application of system analysis tools capable of analyzing various options for managing SNF and HLW. With these tools, integrated waste management system (IWMS) architecture analyses are being conducted to support the future deployment of a comprehensive nuclear waste management system that considers all major back-end aspects of the nuclear fuel cycle (i.e., transportation, storage, and disposal). System analyses and assessments typically use these modeling and simulation tools to investigate implications of changes in various assumptions and parameters such as acceptance rates, receipt logic, facility capacities and capabilities, use of standardized canisters, start and stop dates of facilities, etc. The Next Generation System Analysis Model (NGSAM) is an agent-based simulation toolkit that is used for a system-level simulation and analysis focused on SNF management in the United States. An analyst using NGSAM has the ability to define several factors like the number of storage facilities, capacity at each facility, transportation schedules, shipment rates, and other conditions. NGSAM’s primary purpose is to provide a system analyst with capabilities to model the IWMS and gain insights into SNF and HLW management alternatives including the impact of system choices, associated cost estimates, and development of integrated yet flexible approaches. IWM is also developing the Stakeholder Tool for Assessing Radioactive Transportation (START). START is a web-based geospatial tool developed to provide visualization and initial evaluation of transportation options associated with future SNF and HLW shipment planning and operations. This includes characterizing safety, economic, and environmental conditions on and in proximity to shipment origins as well as along prospective transportation routes. Information from the START tool can be presented/shared as maps, graphics, geospatial files, and tabular form to enable easy data representation and export functionality. The system analysis, NGSAM, and START teams had been working closely for several years before formalizing this collaboration. START provides the SNF routing information for use in NGSAM. System analysts use the NGSAM tool to generate results (schedule, costs, infrastructure acquisitions, shipment rates, etc.). Subject-matter experts and system analysts work together to inform how NGSAM should model the waste management system. Specifically, this paper discusses the collaborations between the system analysis, NGSAM, and START teams and their accomplishments over the past year. Some examples of these efforts include calibrating and adding data to the START output files to meet NGSAM needs, gaining a better understanding of START data used in NGSAM, as well as how updates in START data could result in an improved NGSAM analysis. Detailed examples of various tasks that have been performed by the team will be discussed in the full paper. Continued efforts in this direction are expected in the coming years.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Transportation and System Analysis Collaborations in Support of a Federal Consolidated Interim Storage Facility

The U.S. Department of Energy’s Integrated Waste Management (IWM) program under the Office of Nuclear Energy is planning for the future transportation, storage, and eventual disposal of spent nuclear fuel (SNF) and high-level radioactive waste (HLW) from nuclear power plant and waste custodian sites across the United States. To better enable informed decision-making regarding the back end of the nuclear fuel cycle, the IWM program has been sponsoring the development and application of system analysis tools capable of analyzing various options for managing SNF and HLW. With these tools, integrated waste management system (IWMS) architecture analyses are being conducted to support the future deployment of a comprehensive nuclear waste management system that considers all major back-end aspects of the nuclear fuel cycle (i.e., transportation, storage, and disposal). System analyses and assessments typically use these modeling and simulation tools to investigate implications of changes in various assumptions and parameters such as acceptance rates, receipt logic, facility capacities and capabilities, use of standardized canisters, start and stop dates of facilities, etc. The Next Generation System Analysis Model (NGSAM) is an agent-based simulation toolkit that is used for a system-level simulation and analysis focused on SNF management in the United States. NGSAM’s primary purpose is to provide a system analyst with capabilities to model the IWMS and gain insights into SNF and HLW management alternatives including the impact of system choices, associated cost estimates, and development of integrated yet flexible approaches. An analyst using NGSAM can define several factors like the number of storage facilities, capacity at each facility, transportation schedules, shipment rates, and other conditions. IWM is also developing the Stakeholder Tool for Assessing Radioactive Transportation (START). START is a web-based geospatial tool developed to provide the visualization and initial evaluation of transportation options associated with future SNF and HLW shipment planning and operations. This includes characterizing safety, economic, and environmental conditions at and in proximity to shipment origins as well as along prospective transportation routes. Information from the START tool can be presented/shared as maps, graphics, geospatial files, and tabular form to enable easy data representation and export functionality. The system analysis, NGSAM, and START teams have been working closely for several years before formalizing this collaboration. START provides the SNF transportation routing information for use in NGSAM. System analysts use the NGSAM tool to generate results (schedule, costs, infrastructure acquisitions, shipment rates, etc.). Subject-matter experts and system analysts work together to inform how NGSAM should model the waste management system. Specifically, this paper discusses the collaborations between the system analysis, NGSAM, and START teams and their accomplishments over the past year. Some examples of these efforts include calibrating and adding data to the START output files to meet NGSAM needs, gaining a better understanding of START data used in NGSAM as well as how updates in START data could result in an improved NGSAM analysis. Detailed examples of various tasks that have been performed by the team will be discussed in the full paper. Continued efforts in this direction are expected in the coming years.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1974

A design for a Venus orbital imaging radar mission

A planetary exploration mission to map the surface of Venus is discussed. A review of the Venus exploration program provides a basis for determining the probable scientific requirements for resolution, planetary coverage, etc., for such a mission. From these requirements, the range of possible mission, radar, and spacecraft functional requirements is determined and a single 'point' design is investigated in some detail. This point design, which provides full planet mapping at resolutions better than 200 meters, is based on Mariner-class spacecraft technology, including a conventional bipropellant propulsion system, currently under development, capable of delivering the required payload into a 500-km circular Venus orbit.

Rose, J. R.↗