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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 1,783 records · Page 99
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DOE OSTI2023

Nucleon Resonance Electroexcitation Amplitudes and Emergent Hadron Mass

Understanding the strong interaction dynamics that govern the emergence of hadron mass (EHM) represents a challenging open problem in the Standard Model. In this paper we describe new opportunities for gaining insight into EHM from results on nucleon resonance (N*) electroexcitation amplitudes (i.e., γvpN* electrocouplings) in the mass range up to 1.8 GeV for virtual photon four-momentum squared (i.e., photon virtualities Q2) up to 7.5 GeV2 available from exclusive meson electroproduction data acquired during the 6-GeV era of experiments at Jefferson Laboratory (JLab). These results, combined with achievements in the use of continuum Schwinger function methods (CSMs), offer new opportunities for charting the momentum dependence of the dressed quark mass from results on the Q2-evolution of the γvpN* electrocouplings. This mass function is one of the three pillars of EHM and its behavior expresses influences of the other two, viz. the running gluon mass and momentum-dependent effective charge. A successful description of the Δ(1232)3/2+ and N(1440)1/2+ electrocouplings has been achieved using CSMs with, in both cases, common momentum-dependent mass functions for the dressed quarks, for the gluons, and the same momentum-dependent strong coupling. The properties of these functions have been inferred from nonperturbative studies of QCD and confirmed, e.g., in the description of nucleon and pion elastic electromagnetic form factors. Parameter-free CSM predictions for the electrocouplings of the Δ(1600)3/2+ became available in 2019. The experimental results obtained in the first half of 2022 have confirmed the CSM predictions. We also discuss prospects for these studies during the 12-GeV era at JLab using the CLAS12 detector, with experiments that are currently in progress, and canvass the physics motivation for continued studies in this area with a possible increase of the JLab electron beam energy up to 22 GeV. Such an upgrade would finally enable mapping of the dressed quark mass over the full range of distances (i.e., quark momenta) where the dominant part of hadron mass and N* structure emerge in the transition from the strongly coupled to perturbative QCD regimes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1981

Sixth Annual Flight Mechanics/Estimation Theory Symposium

Methods of orbital position estimation were reviewed. The problem of accuracy in orbital mechanics is discussed and various techniques in current use are presented along with suggested improvements. Of special interest is the compensation for bias in satelliteborne instruments due to attitude instabilities. Image processing and correctional techniques are reported for geodetic measurements and mapping.

Lefferts, E.↗
NASA NTRS1984

Telemetry Speeds Forest-Fire Control

Airborne system rapidly delivers hard copy to firefighters. Sensors in airplane send data to ground station for image processing. Imagery immediately transferred to U.S. Geologic Survey (USGS) maps by photo interpreter. Maps transmitted by telecopies directly to fire-control camps. Receipt by fire camp less than 10 minutes. Information aids in decisions involving deployment of firefighters and equipment, flood control, monitoring oilspills, observing thermal currents, and pollutions monitoring.

Arvesen, J. C.↗
NASA NTRS1985

Advanced Gas Turbine (AGT) technology report

Engine testing, ceramic component fabrication and evaluation, component performance rig testing, and producibility experiments at Pontiac comprised AGT 100 activities of this period, January to December 1984. Two experimental engines were available and allowed the evaluation of eight experimental assemblies. Operating time accumulated was 115 hr of burning and 156 hr total. Total cumulative engine operating time is now 225 hr. Build number 11 and 12 of engine S/N 1 totaled 28 burning hours and constituted a single assembly of the engine core--the compressor, both turbines, and the gearbox. Build number 11 of engine S/N 1 included a 1:07 hr continuous test at 100% gasifier speed (86,000 rpm). Build number 8 of engine S/N 2 was the first engine test with a ceramic turbine rotor. A mechanical loss test of an engine assembly revealed the actual losses to be near the original design allowance. Component development activity included rig testing of the compressor, combustor, and regenerator. Compressor testing was initiated on a rig modified to control the transfer of heat between flow path, lubricating oil, and structure. Results show successful thermal decoupling of the rig and lubricating/cooling oil. Rig evaluation of a reduced-friction compressor was initiated. Combustor testing covered qualification of ceramic parts for engine use, mapping of operating range limits, and evaluation of a relocated igniter plug. Several seal refinements were tested on the hot regenerator rig. An alternate regenerator disk, extruded MAS, was examined and found to be currently inadequate for the AGT 100 application. Also, a new technique for measuring leakage was explored on the regenerator rig. Ceramic component activity has focused on the development of state-of-the-art material strength characteristics in full-scale hardware. Injection-molded sintered alpha-SiC rotors were produced at Carborundum in an extensive process and tool optimization study.

Source record↗
NASA NTRS1986

Io

The present work reviews the history of Io studies and describes the current level of understanding of Io's physics, chemistry, geology, orbital dynamics, and geophysics. Consideration is given to the satellite's internal, superficial, atmospheric, plasma, and magnetospheric properties and how they interrelate. A pictorial map of Io's surface based on Voyager 1 and 2 images is presented. It is found that Io's surface color and spectra are dominated by sulfur compounds which may include various sulfur allotropes. Volcanic processes yielding three kinds of surface features (vent regions, plains, and mountains) dominate Io's surface geology. The Io plasma torus corotates with Jupiter's magnetic field in the plane of Jupiter's centrifugal equator centered at Io's orbital radius.

Nash, Douglas B.↗
NASA NTRS1988

History of wildland fires on Vandenberg Air Force Base, California

The fire history of the past 50 years for Vandenberg AFB, California was determined using aerial photography, field investigation, and historical and current written records. This constitutes a record of the vegetation age classes for the entire base. The location, cause, and fuel type for sixty fires from this time period were determined. The fires were mapped and entered into a geographic infomation system (GIS) for Vandenberg. Fire history maps derived from this GIS were printed at 1:9600 scale and are on deposit at the Vandenberg Environmental Task Force Office. Although some ecologically significant plant communities on Vandenberg are adapted to fire, no natural fire frequency could be determined, since only one fire possibly caused by lightning occurred in the area now within the base since 1937. Observations made during this study suggest that burning may encourage the invasion of exotic species into chaparral, in particular Burton Mesa or sandhill chaparral, an unusual and geographically limited form of chaparral found on the base.

Hickson, Diana E.↗
NASA NTRS1988

Detailed operating characteristics of a 30-kW ammonia arcjet engine with a contoured nozzle

Detailed experimental investigations were conducted to define the operating characteristics of a 30-kW type, arcjet engine with a contoured nozzle. The experiments were conducted in a fully instrumented facility with the engine mounted on a thrust stand. Engine performance was mapped over a power range of 10.6 to 23.0 kW with a mass flow range of 0.175 to 0.350 g/s. The data is presented in graphical form with the relationships between arc potential, arc current, power, thrust, specific impulse and thrust efficiency presented. This paper provides the first detailed accounting of arcjet operation with a contoured nozzle. Further theoretical and experimental work needs to be done to fully explain many of the features exhibited by the data.

Deininger, William D.↗
NASA NTRS1990

Estimates of the zonal slope and seasonal transport of the Atlantic North Equatorial Countercurrent

Data from six inverted echo sounder moorings and the Geosat satellite altimeter are used to examine the seasonal variability of sea surface elevation. Monthly sea level maps are constructed using a contemporaneous subsurface temperature survey to provide a reference sea level field. The maps are then used to describe the origin and structure of the western tropical Atlantic North Equatorial Countercurrent (NECC) during a two-year period beginning in November 1987. The data reveal a zonal current which is confined between 3 deg N and 9 deg N with a typical width of 300 km. The NECC flows strongly eastward during November and December 1986 and May 1987 through January 1988. The reappearance of the current is then delayed until August, but the current flows strongly from August until the end of the record in October 1988. Volume transport is estimated for the two-year period from surface elevation by approximating the vertical structure of the ocean as a two-layer fluid. It is found that the NECC has a maximum transport of 40 x 10 to the 6th cu m/s at 38 deg W.

Carton, James A.↗
NASA NTRS1991

The comet rendezvous asteroid flyby mission: A status report

The Comet Rendezvous Asteroid Flyby (CRAF) mission received a new start in fiscal year 1990. CRAF will match orbits with an active short-period comet and follow it around the Sun, making scientific measurements of the nucleus, coma, and tail. The Imaging system will map the nucleus surface at a resolution of 1 meter/line-pair or better, while Visible and Infrared Mapping Spectrometer (VIMS) and Thermal Infrared Radiometer Experiment (TIREX) will produce spectral and thermal maps of the surface. Onboard instruments will collect cometary dust, ice, and gases and perform elemental and molecular analysis. A suite of fields and particles instruments will observe the solar wind interaction with the cometary atmosphere and tail. Radio tracking of the spacecraft will provide an accurate measure of the nucleus mass and higher harmonics in the comet's gravity field. En route to the comet, the spacecraft will make a close flyby of a large asteroid, preferably a primitive type from the outer main belt. Observations at the asteroid include remote sensing mapping of the surface, detection of any solar wind interaction observable at the flyby distance, and measurement of the asteroid mass to better than 10 percent accuracy. Detailed design of the CRAF spacecraft is currently underway at the Jet Propulsion Laboratory (JPL). Recent mass growth has necessitated a switch to Venus-Earth gravity assist type trajectories, similar to that used by the Galileo spacecraft. These trajectories require longer flight times from launch to rendezvous with the target comet. The details of the current baseline mission, spacecraft design, and instrument payload will be reviewed.

Weissman, Paul R.↗
NASA NTRS1993

The Los Alamos neutron spectrometer for the Lunar Scout-1 mission

We review the current status of the Los Alamos program to develop a neutron spectrometer for the Lunar Scout-1 mission, which is the first of two such missions to obtain global compositional, gravity, topography, and image maps of the lunar surface during nominal one-year missions. The neutron spectrometer will measure fast and slow (epithermal and thermal) neutrons in the ranges of 0.5 MeV to 25 MeV and 0.01 eV to more than 1 keV, respectively. The neutron spectrometer will consist of two independent instruments, a fast-neutron one, and a thermal and epithermal one. The measured neutron fluxes are very sensitive to hydrogen in the top meter of the lunar surface and provide additional information about lunar composition.

Auchampaugh, George↗
NASA NTRS1995

Substorm theories: United they stand, divided they fall

Consensus on the timing and mapping of substorm features has permitted a synthesis of substorm models. Within the synthesis model the mechanism for onset of substorm expansion is still unknown. Possible mechanisms are: growth of an ion tearing mode, current disruption by a cross-field current instability, and magnetosphere-ionosphere coupling. While the synthesis model is consistent with overall substorm morphology, including near-Earth onset, none of the onset theories, taken individually, appear to account for substorm expansion onset. A grand synthesis with unification of the underlying onset theories appears necessary.

Erickson, Gary M.↗
NASA NTRS2000

Internal Wave Study in the South China Sea Using SAR

Recently, the internal wave distribution maps in the China Seas have been compiled from hundreds of ERS-1/2, RADARSAT, and Space Shuttle SAR (Synthetic Aperture Radar) images from 1993 to 1999. Based on internal wave distribution map, most of internal waves in the northeast part of South China Sea were propagating westward. The wave crest can be as long as 200 km with amplitude of 100 m due to strong current from the Kuroshio branching out into the South China Sea. Based on the observations from drilling rigs near DongSha Island by Amoco Production Co., the solitons may be generated in a 4 km wide channel between Batan and Sabtang islands in Luzon Strait. The proposed generation mechanism is similar to the lee wave formation from a shallow topography. Both depression and elevation internal waves have been observed in the same RADARSAT ScanSAR image on May 4, 1998 near DongSha Island. Furthermore, depression and elevation internal waves have also been observed by SAR at the same location on the shelf in April and June, 1993 (in different seasons) respectively. Numerical models have been used to interpret their generation mechanism and evolution processes. Based on the SAR images, near DongSha Island, the westward propagating huge internal solitons are often encountered and diffracted/broken by the coral reefs on the shelf. After passing the island, the diffracted waves will re-merge or interact with each other. It has been observed that after the nonlinear wave-wave interaction, the phase of wave packet is shifted and wavelength is also changed. Examples of mesoscale features observed in SAR images, such as fronts, raincells, bathymetry, ship wakes, and oil spills will be presented. Recent mooring measurements in April 1999 near Dongsha Island, future field test ASIAEX (Asian Seas International Acoustics Experiment) planned for April 2001, and some pretest survey data will be discussed in this paper.

Liu, Antony K.↗
NASA NTRS2002

Calibration of the Shuttle Ozone Limb Sounding Experiment (SOLSE) and the Limb Ozone Retrieval Experiment (LORE)

The calibration and characterization of two new instruments designed to retrieve ozone profiles into the lower stratosphere will be presented. These instruments will fly as a single payload on the Space Shuttle Columbia currently scheduled to lift off July 11, 2002. The purpose of SOLSE (Shuttle Ozone Limb Sounding Experiment) and LORE (Limb Ozone Retrieval Experiment) is to provide a thorough test of the limb ozone retrieval technique, which is being employed on several satellite instruments currently deployed or planned for deployment in the near future. OSIRIS (Optical Spectrograph and Infrared Imager System) and SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) are already in orbit, while OMPS (the Ozone Mapping and Profiler Suite) is planned as the primary US ozone monitoring instrument in the next decade.. SOLSE is a Czerny-Turner spectrograph utilizing a 1k x 1k cooled CCD at the focal plane and covering the spectral range of 310-380 nm in the ultraviolet and 535-865 nm in the visible to near infrared. LORE is a 5 channel filter radiometer with center band wavelengths of 322, 350, 603, 675, and 1000 nm. The focus of this paper will be on measurements of the SOLSE spectrograph performance in the limb-viewing configuration including stray light rejection, spatial and spectral resolution and absolute radiometric response.

Janz, S. J.↗
NASA NTRS2003

Preserving the Finger Lakes for the Future: A Prototype Decision Support System for Water Resource Management, Open Space, and Agricultural Protection

As described herein, this project has progressed well, with the initiation or completion of a number of program facets at programmatic, technical, and inter-agency levels. The concept of the Virtual Management Operations Center has taken shape, grown, and has been well received by parties from a wide variety of agencies and organizations in the Finger Lakes region and beyond. As it has evolved in design and functionality, and to better illustrate its current focus for this project, it has been given the expanded name of Watershed Virtual Management Operations Center (W-VMOC). It offers the advanced, compelling functionality of interactive 3D visualization interfaced with 2D mapping, all accessed via Internet or virtually any kind of distributed computer network. This strong foundation will allow the development of a Decision Support System (DSS) with anticipated enhanced functionality to be applied to the myriad issues involved in the wise management of the Finger Lakes region.

Brower, Robert↗
NASA NTRS1997

Radiation dosimetry measurements with real time radiation monitoring device (RRMD)-II in Space Shuttle STS-79

The real-time measurement of radiation environment was made with an improved real-time radiation monitoring device (RRMD)-II onboard Space Shuttle STS-79 (S/MM#4: 4th Shuttle MIR Mission, at an inclination angle of 51.6 degrees and an altitude of 250-400km) for 199 h during 17-25 September, 1996. The observation of the detector covered the linear energy transfer (LET) range of 3.5-6000 keV/micrometer. The Shuttle orbital profile in this mission was equivalent to that of the currently planned Space Station, and provided an opportunity to investigate variations in count rate and dose equivalent rate depending on altitude, longitude, and latitude in detail. Particle count rate and dose equivalent rate were mapped geographically during the mission. Based on the map of count rate, an analysis was made by dividing whole region into three regions: South Atlantic Anomaly (SAA) region, high latitude region and other regions. The averaged absorbed dose rate during the mission was 39.3 microGy/day for a LET range of 3.5-6000 keV/micrometer. The corresponding average dose equivalent rates during the mission are estimated to be 293 microSv/day with quality factors from International Commission on Radiological Protection (ICRP)-Pub. 60 and 270 microSv/day with quality factors from ICRP-Pub. 26. The effective quality factors for ICRP-Pub. 60 and 26 are 7.45 and 6.88, respectively. From the present data for particles of LET > 3.5keV/micrometer, we conclude that the average dose equivalent rate is dominated by the contribution of galactic cosmic ray (GCR) particles. The dose-detector depth dependence was also investigated.

manned↗
NASA NTRS2010

Oscillation of Angiogenesis with Vascular Dropout in Diabetic Retinopathy by VESsel GENeration Analysis (VESGEN)

PURPOSE. Vascular dropout and angiogenesis are hallmarks of the progression of diabetic retinopathy (DR). However, current evaluation of DR relies on grading of secondary vascular effects, such as microaneurysms and hemorrhages, by clinical examination instead of by evaluation of actual vascular changes. The purpose of this study was to map and quantify vascular changes during progression of DR by VESsel GENeration Analysis (VESGEN). METHODS. In this prospective cross-sectional study, 15 eyes with DR were evaluated with fluorescein angiography (FA) and color fundus photography, and were graded using modified Early Treatment Diabetic Retinopathy Study criteria. FA images were separated by semiautomatic image processing into arterial and venous trees. Vessel length density (L(sub v)), number density (N(sub v)), and diameter (D(sub v)) were analyzed in a masked fashion with VESGEN software. Each vascular tree was automatically segmented into branching generations (G(sub 1)...G(sub 8) or G(sub 9)) by vessel diameter and branching. Vascular remodeling status (VRS) for N(sub v) and L(sub v) was graded 1 to 4 for increasing severity of vascular change. RESULTS. By N(sub v) and L(sub v), VRS correlated significantly with the independent clinical diagnosis of mild to proliferative DR (13/15 eyes). N(sub v) and L(sub v) of smaller vessels (G(sub >=6) increased from VRS1 to VRS2 by 2.4 X and 1.6 X, decreased from VRS2 to VRS3 by 0.4 X and 0.6X, and increased from VRS3 to VRS4 by 1.7 X and 1.5 X (P < 0.01). Throughout DR progression, the density of larger vessels (G(sub 1-5)) remained essentially unchanged, and D(sub v1-5) increased slightly. CONCLUSIONS. Vessel density oscillated with the progression of DR. Alternating phases of angiogenesis/neovascularization and vascular dropout were dominated first by remodeling of arteries and subsequently by veins.

Parsons-Wingerter, Patricia↗
NASA NTRS2010

Measurement of the Isotopic Signatures of Water on Mars: Implications for Studying Methane

The recent discovery of methane on Mars has led to much discussion concerning its origin. On Earth, the isotopic signatures of methane vary with the nature of its production. Specifically, the ratios among 12CH4, 13CH4, and 12CH3D differ for biotic and abiotic origins. On Mars, measuring these ratios would provide insights into the origins of methane and measurements of water isotopologues co-released with methane would assist in testing their chemical relationship. Since 1997, we have been measuring HDO and H2O in Mars atmosphere and comparing their ratio to that in Earth s oceans. We recently incorporated a line-by-line radiative transfer model (LBLRTM) into our analysis. Here, we present a map for [HDO]/[H2O] along the central meridian (1541W) for Ls 501. From these results, we constructed models to determine the observational conditions needed to quantify the isotopic ratios of methane in Mars atmosphere. Current ground-based instruments lack the spectral resolution and sensitivity needed to make these measurements. Measurements of the isotopologues of methane will likely require in situ sampling.

Novak, R. E.↗
NASA NTRS2012

A Framework for Simulating Turbine-Based Combined-Cycle Inlet Mode-Transition

A simulation framework based on the Memory-Mapped-Files technique was created to operate multiple numerical processes in locked time-steps and send I/O data synchronously across to one-another to simulate system-dynamics. This simulation scheme is currently used to study the complex interactions between inlet flow-dynamics, variable-geometry actuation mechanisms, and flow-controls in the transition from the supersonic to hypersonic conditions and vice-versa. A study of Mode-Transition Control for a high-speed inlet wind-tunnel model with this MMF-based framework is presented to illustrate this scheme and demonstrate its usefulness in simulating supersonic and hypersonic inlet dynamics and controls or other types of complex systems.

Le, Dzu K.↗