SEARCH · Search NASA

Results for “Floating zone”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23

All sources NASA NTRS DOE OSTI

DOE OSTI2018

A genetic meta-algorithm-assisted inversion approach: hydrogeological study for the determination of volumetric rock properties and matrix and fluid parameters in unsaturated formations

An evolutionary inversion approach is suggested for the interpretation of nuclear and resistivity logs measured by direct-push tools in shallow unsaturated sediments. The efficiency of formation evaluation is improved by estimating simultaneously (1) the petrophysical properties that vary rapidly along a drill hole with depth and (2) the zone parameters that can be treated as constant, in one inversion procedure. In the workflow, the fractional volumes of water, air, matrix and clay are estimated in adjacent depths by linearized inversion, whereas the clay and matrix properties are updated using a float-encoded genetic meta-algorithm. The proposed inversion method provides an objective estimate of the zone parameters that appear in the tool response equations applied to solve the forward problem, which can significantly increase the reliability of the petrophysical model as opposed to setting these parameters arbitrarily. The global optimization meta-algorithm not only assures the best fit between the measured and calculated data but also gives a reliable solution, practically independent of the initial model, as laboratory data are unnecessary in the inversion procedure. The feasibility test uses engineering geophysical sounding logs observed in an unsaturated loessy-sandy formation in Hungary. The multi-borehole extension of the inversion technique is developed to determine the petrophysical properties and their estimation errors along a profile of drill holes. The genetic meta-algorithmic inversion method is recommended for hydrogeophysical logging applications of various kinds to automatically extract the volumetric ratios of rock and fluid constituents as well as the most important zone parameters in a reliable inversion procedure.

58 GEOSCIENCES↗

DOE OSTI2016

Heat Transfer Model of a Small-Scale Waste Glass Melter with Cold Cap Layer

At the Hanford site in the state of Washington, more than 56 million gallons of radioactive waste is stored in underground tanks. The cleanup plan for this waste is vitrification at the Waste Treatment Plant (WTP), currently under construction. At the WTP, the waste will be blended with glass-forming materials and heated to 1423K, then poured into stainless steel canisters to cool and solidify. A fundamental understanding of the glass batch melting process is needed to optimize the process to reduce cost and decrease the life cycle of the cleanup effort. The cold cap layer that floats on the surface of the glass melt is the primary reaction zone for the feed-to-glass conversion. The conversion reactions include water release, melting of salts, evolution of batch gases, dissolution of quartz and the formation of molten glass. Obtaining efficient heat transfer to this region is crucial to achieving high rates of glass conversion. Computational fluid dynamics (CFD) modeling is being used to understand the heat transfer dynamics of the system and provide insight to optimize the process. A CFD model was developed to simulate the DM1200, a pilot-scale melter that has been extensively tested by the Vitreous State Laboratory (VSL). Electrodes are built into the melter to provide Joule heating to the molten glass. To promote heat transfer from the molten glass into the reactive cold cap layer, bubbling of the molten glass is used to stimulate forced convection within the melt pool. A three-phase volume of fluid approach is utilized to model the system, wherein the molten glass and cold cap regions are modeled as separate liquid phases, and the bubbling gas and plenum regions are modeled as one lumped gas phase. The modeling of the entire system with a volume of fluid model allows for the prescription of physical properties on a per-phase basis. The molten glass phase and the gas phase physical properties are obtained from previous experimental work. Finding representative properties for the cold cap region is more difficult, as this region is not a true liquid, but rather a multilayer region consisting of a porous and a foamy layer. Physical properties affecting heat transfer, namely the thermal conductivity and heat capacity, have been fit to closely match data and observations from laboratory experiments. Data from xray tomography and quenching of laboratory-scale cold caps provide insight into the topology of bubble distribution within the cold cap at various temperatures. Heat transfer within the melter was validated by comparison with VSL data for the pilot-scale melter.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2025

Integrating Offshore Wind Into Competitive Renewable Energy Zones (CREZ) for the Philippines

The Philippines is aiming to jumpstart a domestic offshore wind industry and has incorporated offshore wind into several planning efforts. In parallel, the Philippines has also been a leader in incorporating renewable energy zones (REZs) into their power sector development and transmission plans. The objective of this study, conducted by the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) in partnership with the Philippines Department of Energy (PDOE), is to incorporate offshore wind resources into the Philippines' already established competitive renewable energy zones (CREZs) to support national transmission planning, thereby merging these two previously disparate workstreams and implementing a key recommendation from the World Bank's offshore wind roadmap for the Philippines.

17 WIND ENERGY↗

DOE OSTI2025

Integrating Offshore Wind Into Competitive Renewable Energy Zones (CREZ) for the Philippines [Slides]

17 WIND ENERGY↗

NASA NTRSDate not supplied

Effects of Background Pressure and Electrical Configuration on the Velocity Field of the HERMeS Hall Thruster

A Laser-Induced Fluorescence test was performed during risk reduction testing on the HERMeS Hall thruster. This article focuses on the portion of the test to study trends in the ion acceleration characteristics with varying anode mass flow rate, background pressure, and electrical configuration. The acceleration zone of the HERMeS Hall thruster was observed to move upstream as the anode mass flow rate decreased and upstream as the background pressure increased. Examination of the characteristics of the ions near the pole covers suggested the possibility that thruster was no longer magnetically shielded at the extreme conditions of very low anode mass flow rate and high background pressure. The acceleration zone was also observed to move slightly upstream when the thruster body was floated as opposed to cathode-tied and did not move appreciably when the thruster body was grounded to the vacuum facility. Characteristics of the ions bombarding the pole covers did not vary across the tested electrical configurations.

Electric Propulsion↗

DOE OSTI2015

Planets in other universes: habitability constraints on density fluctuations and galactic structure

Motivated by the possibility that different versions of the laws of physics could be realized within other universes, this paper delineates the galactic structure parameters that allow for habitable planets and revisits constraints on the amplitude Q of the primordial density fluctuations. Previous work indicates that large values of Q lead to galaxies so dense that planetary orbits cannot survive long enough for life to develop. Small values of Q lead to delayed star formation, loosely bound galaxies, and compromised heavy element retention. This work generalizes previous treatments in the following directions: [A] We consider models for the internal structure of the galaxies, including a range of stellar densities, and find the fraction of the resulting galactic real estate that allows for stable, long-lived planetary orbits. [B] For high velocity encounters, we perform a large ensemble of numerical simulations to estimate cross sections for the disruption of planetary orbits due to interactions with passing stars. [C] We consider the background radiation fields produced by the galaxies: if a galaxy is too compact, the night sky seen from a potentially habitable planet can provide more power than the host star. [D] One consequence of intense galactic background radiation fields is that some portion of the galaxy, denoted as the Galactic Habitable Zone, will provide the right flux levels to support habitable planets for essentially any planetary orbit including freely floating bodies (but excluding close-in planets). As the value of Q increases, the fraction of stars in a galaxy that allow for (traditional) habitable planets decreases due to both orbital disruption and the intense background radiation. However, the outer parts of the galaxy always allow for habitable planets, so that the value of Q does not have a well-defined upper limit (due to scattering or radiation constraints). Moreover, some Galactic Habitable Zones are large enough to support more potentially habitable planets than the galaxies found in our universe. These results suggest that the possibilities for habitability in other universes are somewhat more favorable and far more diverse than previously imagined.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1977

Groundwater studies in arid areas in Egypt using LANDSAT satellite images

Various features are interpreted which have strong bearing on groundwater in the arid environment. These include the nature of geological and lithologic units, structural lineaments, present and old drainage systems, distribution and form of water pools, geomorphologic units, weathering surfaces and other weathering phenomena, desert soils, sand dunes and dune sand accumulations, growths of natural vegetation and agriculture, and salt crusts and other expressions of salinization. There are many impressive examples which illustrate the significance of satellite image interpretation on the regional conditions of groundwater which could be traced and interconnected over several tens or even several hundreds of kilometers. This is especially true in the northern Western Desert of Egypt where ground water issuing from deep strata comes to the surface along ENE-WSW and ESE-WNW fault lines and fracture systems. Another striking example is illustrated by the occurrence of fresh to brackish groundwater on the Mediterranean Sea Coastal Zone of the Western Desert where the groundwater is found in the form of lenses floating on the saline sea water.

Elshazly, E. M.↗

DOE OSTI2023

Isolating the Source Region of Infrasound Travel Time Variability Using Acoustic Sensors on High-Altitude Balloons

High-altitude balloons carrying infrasound sensor payloads can be leveraged toward monitoring efforts to provide some advantages over other sensing modalities. On 10 July 2020, three sets of controlled surface explosions generated infrasound waves detected by a high-altitude floating sensor. One of the signal arrivals, detected when the balloon was in the acoustic shadow zone, could not be predicted via propagation modeling using a model atmosphere. Considering that the balloon’s horizontal motion showed direct evidence of gravity waves, we examined their role in infrasound propagation. Implementation of gravity wave perturbations to the wind field explained the signal detection and aided in correctly predicting infrasound travel times. Our results show that the impact of gravity waves is negligible below 20 km altitude; however, their effect is important above that height. The results presented here demonstrate the utility of balloon-borne acoustic sensing toward constraining the source region of variability, as well as the relevance of complexities surrounding infrasound wave propagation at short ranges for elevated sensing platforms.

47 OTHER INSTRUMENTATION↗

NASA NTRS2023

Facility Effects on the Ion Characteristics of A 12.5-Kw Hall Thruster

During a laser-induced fluorescence test of a 12.5-kW magnetically-shielded Hall thruster, ion characteristics in the discharge channel and near the poles were measured as the background pressure and electrical configuration were varied. The acceleration zone of the thruster moved upstream by 2% and 10% of the channel length when the background pressure was raised to 1.8 times and 7 times the lowest achievable pressure, respectively. Examination of the characteristics of the ions near the pole covers suggested that as the background pressure decreased the pole covers may be experiencing more erosion. When operating at a discharge voltage of 300 V, the acceleration zone was observed to be at the same location for all electrical configurations. When operating at a discharge voltage of 600V, the acceleration zone was observed to move 3% of the channel length upstream when the thruster body was floated instead of tied to the cathode or grounded to the facility. Characteristics of the ions bombarding the pole covers did not vary across the tested electrical configurations. This observation combined with thruster body voltage measurements suggested that varying the electrical configuration only affected the thruster body sheath voltage and did not affect the plasma potential beyond the sheath.

Electric propulsion↗

NASA NTRS1949

Systematic model researches on the stability limits of the DVL series of float designs

To determine the trim range in which a seaplane can take off without porpoising, stability tests were made of a Plexiglas model, composed of float, wing, and tailplane, which corresponded to a full-size research airplane. The model and full-size stability limits are in good agreement. After all structural parts pertaining to the air frame were removed gradually, the aerodynamic forces replaced by weight forces, and the moment of inertia and position of the center of gravity changed, no marked change of limits of the stable zone was noticeable. The latter, therefore, is for practical purposes affected only by hydrodynamic phenomena. The stability limits of the DVL family of floats were determined by a systematic investigation independent of any particular sea-plane design, thus a seaplane may be designed to give a run free from porpoising.

Sottorf, W.↗

NASA NTRS1975

Interdisciplinary application and interpretation of EREP data within the Susquehanna River Basin

The author has identified the following significant results. It has become that lineaments seen on Skylab and ERTS images are not equally well defined, and that the clarity of definition of a particular lineament is recorded somewhat differently by different interpreters. In an effort to determine the extent of these variations, a semi-quantitative classification scheme was devised. In the field, along the crest of Bald Eagle Mountain in central Pennsylvania, statistical techniques borrowed from sedimentary petrography (point counting) were used to determine the existence and location of intensely fractured float rock. Verification of Skylab and ERTS detected lineaments on aerial photography at different scales indicated that the brecciated zones appear to occur at one margin of the 1 km zone of brecciation defined as a lineament. In the Lock Haven area, comparison of the film types from the SL4 S190A sensor revealed the black and white Pan X photography to be superior in quality for general interpretation to the black and white IR film. Also, the color positive film is better for interpretation than the color IR film.

Mcmurtry, G. J.↗

DOE OSTI2017

Final Scientific/Technical Report: Characterizing the Response of the Cascadia Margin Gas Hydrate Reservoir to Bottom Water Warming Along the Upper Continental Slope

The objective of this project is to understand the response of the WA margin gas hydrate system to contemporary warming of bottom water along the upper continental slope. Through pre-cruise analysis and modeling of archive and recent geophysical and oceanographic data, we (1) inventoried bottom simulating reflectors along the WA margin and defined the upper limit of gas hydrate stability, (2) refined margin-wide estimates of heat flow and geothermal gradients, (3) characterized decadal scale temporal variations of bottom water temperatures at the upper continental slope of the Washington margin, and (4) used numerical simulations to provide quantitative estimates of how the shallow boundary of methane hydrate stability responds to modern environmental change. These pre-cruise results provided the context for a systematic geophysical and geochemical survey of methane seepage along the upper continental slope from 48° to 46°N during a 10-day field program on the R/V Thompson from October 10-19, 2014. This systematic inventory of methane emissions along this climate-sensitive margin corridor and comprehensive sediment and water column sampling program provided data and samples for Phase 3 of this project that focused on determining fluid and methane sources (deep-source vs. shallow; microbial, thermogenic, gas hydrate dissociation) within the sediment, and how they relate to contemporary intermediate water warming. During the 2014 research expedition, we sampled nine seep sites between ~470 and 520 m water depth, within the zone of predicted methane hydrate retreat over the past 40 years. We imaged 22 bubble plumes with heights commonly rising to ~300 meters below sea level with one reaching near the sea surface. We collected 22 gravity cores and 20 CTD/hydrocasts from the 9 seeps and at background locations (no acoustic evidence of seepage) within the depth interval of predicted downslope retreat of the methane hydrate stability zone. Approximately 300 pore water samples were extracted from the gravity cores, and the pore water was analyzed for a comprehensive suite of solutes, gases, and stable isotope ratios. This comprehensive geochemical dataset was used to characterize the fluid and gas source(s) at each of the seep sites surveyed. The primary results of this project are: 1) Bottom simulating reflector-derived heat flow values decrease from 95 mW/m2 10 km east of the deformation front to ~60 mW/m2 60 km landward of the deformation front, with anomalously low values of ~25 mW/m2 on a prominent mid-margin terrace off central Washington. 2) The temperature of the incoming sediment/ocean crust interface at the deformation front ranges between 164-179 oC off central Washington, and the 350 oC isotherm at the top of the subducting ocean crust occurs 95 km landward of the deformation front. Differences between BSR-derived heat flow and modeled conductive heat flow suggest mean upward fluid flow rates of 0.4 cm/yr across the margin, with local regions (e.g. fault zones) exhibiting fluid flow rates up to 3.5 cm/yr. 3) A compilation of 2122 high-resolution CTD, glider, and Argo float temperature profiles spanning the upper continental slope of the Washington margin from the years 1968 to 2013 show a long-term warming trend that ranges from 0.006-0.008 oC/yr. Based on this long-term bottom water warming, we developed a 2-D thermal model to simulate the change in sediment temperature distribution over this period, along with the downslope retreat of the methane hydrate stability field. Over the 43 years of the simulation, the thermal disturbance propagated 30 m into the sediment column, causing the base of the methane hydrate stability field to shoal ~13 m and to move ~1 km downslope. 4) A preliminary analysis of seafloor observations and mid-water column acoustic data to detect bubble plumes was used to characterize the depth distribution of seeps along the Cascadia margin. These results indicate high bubble plume densities along the continental shelf at water depths <180 m and at the upper limit of methane hydrate stability along the Washington margin. 5) The majority of the seeps cored during the 2014 research expedition on the R/V Thompson contained abundant authigenic carbonate indicating that they are locations of long-lived seepage rather than emergent seep systems related to methane hydrate dissociation. Despite the evidence for enhanced methane seepage at the upper limit of methane hydrate stability along the Washington margin, we found no unequivocal evidence for active methane hydrate dissociation as a source of fluid and gas at the seeps surveyed. The pore fluid and bottom water chemistry shows that the seeps are fed by a variety of fluid and methane sources, but that methane hydrate dissociation, if occurring, is not widespread and is only a minor source (below the detection limit of our methods). Collectively, these results provide a significant advance in our understanding of the thermal structure of the Cascadia subduction zone and the fluid and methane sources feeding seeps along the upper continental slope of the Washington-sector of the Cascadia margin. Though we did not find unequivocal evidence for methane hydrate dissociation as a source of water and methane at the upper pressure-temperature limit of methane hydrate stability at present, continued warming of North Pacific Intermediate Water in the future has the potential to impact the methane hydrate reservoir in sediments at greater depths along the slope. Thus, this study provides a strong foundation and the necessary characterization of the background state of seepage at the upper limit of methane hydrate stability for future investigations of this important process.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2023

Carbon Outgassing in the Antarctic Circumpolar Current Is Supported by Ekman Transport From the Sea Ice Zone in an Observation‐Based Seasonal Mixed‐Layer Budget

Despite its importance for the global cycling of carbon, there are still large gaps in our understanding of the processes driving annual and seasonal carbon fluxes in the high-latitude Southern Ocean. This is due in part to a historical paucity of observations in this remote, turbulent, and seasonally ice-covered region. Here, we use autonomous biogeochemical float data spanning 6 full seasonal cycles and with circumpolar coverage of the Southern Ocean, complemented by atmospheric reanalysis, to construct a monthly climatology of the mixed layer budget of dissolved inorganic carbon (DIC). We investigate the processes that determine the annual mean and seasonal cycle of DIC fluxes in two different zones of the Southern Ocean—the Sea Ice Zone (SIZ) and Antarctic Southern Zone (ASZ). We find that, annually, mixing with carbon-rich waters at the base of the mixed layer supplies DIC which is, in the ASZ, either used for net biological production or outgassed to the atmosphere. In contrast, in the SIZ, where carbon outgassing and the biological pump are weaker, the surplus of DIC is instead advected northward to the ASZ. In other words, carbon outgassing in the southern Antarctic Circumpolar Current (ACC), which has been attributed to remineralized carbon from deep water upwelled in the ACC, is also due to the wind-driven transport of DIC from the SIZ. These results stem from the first observation-based carbon budget of the circumpolar Southern Ocean and thus provide a useful benchmark to evaluate climate models, which have significant biases in this region.

Sauvé, Jade↗

NASA NTRS1990

Plasma heating, electric fields and plasma flow by electron beam ionospheric injection

The electric fields and the floating potentials of a Plasma Diagnostics Payload (PDP) located near a powerful electron beam injected from a large sounding rocket into the auroral zone ionosphere have been studied. As the PDP drifted away from the beam laterally, it surveyed a region of hot plasma extending nearly to 60 m radius. Large polarization electric fields transverse to B were imbedded in this hot plasma, which displayed large ELF wave variations and also an average pattern which has led to a model of the plasma flow about the negative line potential of the beam resembling a hydrodynamic vortex in a uniform flow field. Most of the present results are derived from the ECHO 6 sounding rocket mission.

Winckler, J. R.↗

NASA NTRS1977

Early history of the moon: Implications of U-Th-Pb and Rb-Sr systematics

Anorthosite 60015 contains the lowest initial Sr-87/Sr-86 ratio yet reported for a lunar sample. The initial ratio is equal to that of the achondrite Angra dos Reis and slightly higher than the lowest measured Sr-87/Sr-86 ratio for an inclusion in the C3 carbonaceous chondrite Allende. The Pb-Pb ages of both Angra does Reis and Allende are 4.62 X 10 to the ninth power yr. Thus, the initial Sr/87/Sr-86 ratio found in lunar anorthosite 60015 strongly supports the hypothesis that the age of the Moon is about 4.65 b.y. The U-238/Pb-204 value estimated for the source of the excess lead in "orange soil" 74220 is approximately 35 and lower than the values estimated for the sources of KREEP (600-1000), high-K (300-600), and low-K (100-300) basalts. From these and other physical, chemical and petrographic results it was hypothesized that (1) the moon formed approximately 4.65 b.y. ago; (2) a global-scale gravitational differentiation occurred at the beginning of lunar history; and (3) the differentiation resulted in a radical chemical and mineralogical zoning in which the U-238/Pb-204 ratios increased toward the surface, with the exception of the low U-238/Pb-204 surficial anorthositic layer which "floated" at the beginning of the differentiation relative to the denser pyroxene-rich material.

Tatsumoto, M.↗

NASA NTRS2019

Air and Water Temperature Relationship and Growth of Hyacinth and Primrose

Temperature is a primary determining factor for plant growth and development so providing an appropriate temperature input is critically important for developing growth models. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA (US Dept. of Agriculture)-sponsored area-wide project including NASA Ames Research Center and State of California Department of Boating and Waterways, uses modeling to assess invasive aquatic plant impacts on ecosystem services in the Delta. Availability of continuous records for monitored temperature is limited and particularly in the case of water temperature the distribution of monitoring is inadequate. This work quantitatively defines the influence of air and water temperature in determining dominant growth rate processes for important floating aquatic invasive plants in the Delta. Since these plants function with portions submerged and above water we wanted to understand the relationship between root zone and shoot zone temperature and ability to use a single temperature inputs in DRAAWP models. Water Hyacinth and Primrose were gown in multiple controlled environment chamber studies with various combinations of root zone and shoot zone temperatures. Long-term growth studies provided integrated response of biomass accumulation and distribution within the canopy. Short-term gas exchange studies provide a time scale for responsiveness to temperature and a short-term study approach to evaluate temperature responses at various stages of canopy development.

Hyacinth↗

NASA NTRS2005

An Application-Based Performance Characterization of the Columbia Supercluster

Columbia is a 10,240-processor supercluster consisting of 20 Altix nodes with 512 processors each, and currently ranked as the second-fastest computer in the world. In this paper, we present the performance characteristics of Columbia obtained on up to four computing nodes interconnected via the InfiniBand and/or NUMAlink4 communication fabrics. We evaluate floating-point performance, memory bandwidth, message passing communication speeds, and compilers using a subset of the HPC Challenge benchmarks, and some of the NAS Parallel Benchmarks including the multi-zone versions. We present detailed performance results for three scientific applications of interest to NASA, one from molecular dynamics, and two from computational fluid dynamics. Our results show that both the NUMAlink4 and the InfiniBand hold promise for application scaling to a large number of processors.

Biswas, Rupak↗

NASA NTRS1978

Instrumentation for dc and low-frequency electric-field measurements on ISEE-A

It has been found that systematic measurements of the various properties of electric fields existing in space are required for an understanding of the plasma environment. Progress has, however, been limited by a lack of opportunities to fly the long antenna-probes required for double-probe measurements. The improved capabilities of ISEE-A should make it possible to conduct systematic studies of the spatial extent and variability of the zone of strong E-fields, or fast convection, in adjacent magnetospheric regions. The objectives of the ISEE-A measurements are discussed along with the symmetric double-probe floating-potential technique and the antenna-probe design. A description of the electronic design is also provided, giving attention to dc-field measurements, spin coupled dc-field measurements, and calibration and plasma impedance measurements.

Heppner, J. P.↗