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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Detection of vapor nanobubbles by small angle neutron scattering (SANS)

Experiments using boiling water on untreated (roughness 100–300 nm) metal surfaces using small-angle neutron scattering (SANS) show the appearance of structures that are 50–70 nm in size when boiling is present. The scattering signal disappears when the boiling ceases, and no change in the signal is detected at any surface temperature condition below saturation. This confirms that the signal is caused by vapor nanobubbles. Two boiling regimes are evaluated herein that differ by the degree of subcooling (3–10 °C). A polydisperse spherical model with a log-normal distribution fits the SANS data well. In conclusion, the size distribution indicates that a large number of nanobubbles exist on the surface during boiling, and some of them grow into large bubbles.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Internal structure of the San Jacinto fault zone at the Ramona Reservation, north of Anza, California, from dense array seismic data

SUMMARY We image the internal structure of the San Jacinto fault zone (SJFZ) near Anza, California, with seismic data recorded by two dense arrays (RA and RR) from ∼42 000 local and ∼180 teleseismic events occurring between 2012 and 2017. The RA linear array has short aperture (∼470 m long with 12 strong motion sensors) and recorded for the entire analysed time window, whereas the RR is a large three-component nodal array (97 geophones across a ∼2.4 km × 1.4 km area) that operated for about a month in September–October 2016. The SJFZ at the site contains three near-parallel surface traces F1, F2 and F3 from SW to NE that have accommodated several Mw > 6 earthquakes in the past 15 000 yr. Waveform changes in the fault normal direction indicate structural discontinuities that are consistent with the three fault surface traces. Relative slowness from local events and delay time analysis of teleseismic arrivals in the fault normal direction suggest a slower SW side than the NE with a core damage zone between F1 and F2. This core damage zone causes ∼0.05 s delay at stations RR26–31 in the teleseismic P arrivals compared with the SW-most station, and generates both P- and S-type fault zone trapped waves. Inversion of S trapped waves indicates the core damaged structure is ∼100 m wide, ∼4 km deep with a Q value of ∼20 and 40 per cent S-wave velocity reduction compared with bounding rocks. Fault zone head waves observed at stations SW of F3 indicate a local bimaterial interface that separates the locally faster NE block from the broad damage zone in the SW at shallow depth and merges with a deep interface that separates the regionally faster NE block from rocks to the SW with slower velocities at greater depth. The multiscale structural components observed at the site are related to the geological and earthquake rupture history at the site, and provide important information on the preferred NW propagation of earthquake ruptures on the San Jacinto fault.

Geochemistry & Geophysics↗
DOE OSTI2024

Dynamics and activity of an ammonia-oxidizing archaea bloom in South San Francisco Bay

Abstract Transient or recurring blooms of ammonia-oxidizing archaea (AOA) have been reported in several estuarine and coastal environments, including recent observations of AOA blooms in South San Francisco Bay. Here, we measured nitrification rates, quantified AOA abundance, and analyzed both metagenomic and metatranscriptomic data to examine the dynamics and activity of nitrifying microorganisms over the course of an AOA bloom in South San Francisco Bay during the autumn of 2018 and seasonally throughout 2019. Nitrification rates were correlated with AOA abundance in quantitative polymerase chain reaction (PCR) data, and both increased several orders of magnitude between the autumn AOA bloom and spring and summer seasons. From bloom samples, we recovered an extremely abundant, high-quality Candidatus Nitrosomarinus catalina-like AOA metagenome-assembled genome that had high transcript abundance during the bloom and expressed >80% of genes in its genome. We also recovered a putative nitrite-oxidizing bacteria metagenome-assembled genome from within the Nitrospinaceae that was of much lower abundance and had lower transcript abundance than AOA. During the AOA bloom, we observed increased transcript abundance for nitrogen uptake and oxidative stress genes in non-nitrifier metagenome-assembled genomes. This study confirms AOA are not only abundant but also highly active during blooms oxidizing large amounts of ammonia to nitrite—a key intermediate in the microbial nitrogen cycle—and producing reactive compounds that may impact other members of the microbial community.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

First Data Acquired on the EQ-SANS Diffractometer at the Spallation Neutron Source

The measurement of the conformation of a Generation-8 Polyamidoamine dendrimer is reported as an initial experiment using the Extended Q-range Small Angle Neutron Scattering (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory (ORNL). The conformation parameters (radius of gyration, thickness of the soft shell etc.) are extracted by model fitting. The results are compared with data collected at the General-Purpose Small Angle Neutron Scattering at the High Flux Isotopic Reactor at ORNL. The comparison shows that the EQ-SANS diffractometer has comparable data statistics and Q resolution with shorter counting time over the measured Q-range.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Visualizing urban microclimate and quantifying its impact on building energy use in San Francisco

© 2019 Association for Computing Machinery. Weather data at nearby airports are usually used in building energy simulation to estimate energy use in buildings or evaluate building design or retrofit options. However, due to urbanization and geography characteristics, local weather conditions can differ significantly from those at airports. This study presents the visualization of 10-year hourly weather data measured at 27 sites in San Francisco, aiming to provide insights into the urban microclimate and urban heat island effect in San Francisco and how they evolve during the recent decade. The 10-year weather data are used in building energy simulations to investigate its influence on energy use and electrical peak demand, which informs the city's policy making on building energy efficiency and resilience. The visualization feature is implemented in CityBES, an open web-based data and computing platform for urban building energy research.

Hong, T↗
DOE OSTI2025

An open-access simulated earthquake ground-motion database for an M7 Hayward Fault earthquake in the San Francisco Bay Region

Comprehensive understanding of earthquake ground motions, particularly in the near-fault region of large-magnitude events, is limited by gaps in strong-motion data. This challenge is prominent in areas with high seismic hazard but infrequent large earthquakes where data is sparse and difficult to interpret. These data limitations lead to uncertainties in the development of site-specific ground motions, which are crucial for engineering risk assessments. To address these challenges, physics-based regional-scale ground-motion simulations have been developed. With the emergence of exaflop-scale computing ecosystems, it is now possible to simulate regional earthquake processes at unprecedented fidelity and generate the large number of fault rupture realizations necessary to characterize both intra- and inter-event ground-motion variability. This article introduces a new database of simulated earthquake ground motions, created for applications in earthquake engineering, earthquake planning, and emergency response. The inaugural version of the database features simulated ground motions for a magnitude 7 Hayward Fault earthquake in the San Francisco Bay Region (SFBR), using the EarthQuake SIMulation (EQSIM) simulation framework and the Graves–Pitarka kinematic rupture model. The aim is to provide high-fidelity, spatially dense, three-component motions generated on the Department of Energy’s (DOE) newest generation of graphics processing unit (GPU)-accelerated supercomputers. These motions are being made openly available to the engineering, scientific, and disaster planning communities. In addition, this work develops protocols for the efficient dissemination of these large data sets and emphasizes community engagement to build confidence in their application. This article discusses the methodology behind the data, underlying software verification and validation, scalable data management, and a user interface for data access. The goal is to facilitate widespread use and elicit expert feedback to maximize the utility and exploitation of simulated motions. While the initial focus is on the San Francisco Region, simulations for additional regions will be added as the DOE program progresses.

Simulated ground-motion database↗
DOE OSTI2022

Induced seismicity potential based on probabilistic geomechanics for the San Juan Basin CarbonSAFE project

Although geologic carbon sequestration projects have yet to induce — or may never induce — a damaging earthquake, experiences from other deep injection industries such as hydraulic fracturing, enhanced geothermal systems, and saltwater disposal suggest that effective quantitative seismic risk assessment is necessary for deep saline carbon capture and sequestration (CCS) projects. One such imminent CCS project is the San Juan Basin CarbonSAFE Phase III program. We use Monte Carlo probabilistic geomechanical analyses combined with observations of the geologic and operational parameters of the San Juan Basin site and suggest that this project is of low-induced seismic risk. The primary analysis is split into four sections. First, we assess the literature for faults and past seismicity, and at least five faulting scenarios are directly relevant. Second, we develop and calibrate an integrated earth model for the project site. Third, we perform Monte Carlo simulations that consider reasonable uncertainties of the geomechanical parameters. Of five tested faulting scenarios, only one presents high Coulomb failure functions, but fourth, we determine the risk to be low based on the combined lack of historical seismicity, the geologic framework of the faulting scenario, and the presence of saltwater injection at the same depth as the proposed supercritical carbon dioxide injection. The most sensitive parameters in the geomechanical calculations are the fault dip and the coefficient of friction. The least sensitive are the fault strike and the orientation of the maximum horizontal principal stress.

58 GEOSCIENCES↗
DOE OSTI2016

Seismic Survey 2016 Metadata at San Emidio, Nevada

1301 Vertical Component seismic instruments were deployed at San Emidio Geothermal field in Nevada in December 2016. The first record starts at 2016-12-05T02:00:00.000000Z (UTC) and the last record ends at 2016-12-11T14:00:59.998000Z (UTC). Data are stored in individual files in one-minute increments. Data includes seismic station locations, seismic data logger specifications, instrumentation specifications, descriptions of data, a fracture finding summary and the final report for the 2016 WHOLESCALE seismic survey done in San Emidio, Nevada.

15 GEOTHERMAL ENERGY↗
DOE OSTI2026

1995 San Diego Region Travel Behavior Survey

The 1995 San Diego Region Travel Behavior Survey was conducted January-June of 1995 under the auspices of the San Diego Association of Governments. The survey was an essential element in the regional study of transportation activity and travel patterns. The survey was designed to examine the relationship between characteristics of households and travel behavior, as well as to provide information state and local decision makers require when considering future regional transportation needs and investments. In total, 2,375 households were recruited to participate in the study. Of these, 2,062 households completed travel diaries, and the information was retrieved from all household members older than age five. 2,049 were successfully geocoded to California state plane coordinates for home addresses. A total of 17,060 trips were profiled in the course of this survey during the assigned 24-hour weekday.

1Hz data↗
DOE OSTI2011

Experimental Evidence of Super Densification of Adsorbed Hydrogen by in-situ Small Angle Neutron Scattering (SANS)

Entrapping hydrogen molecules within the nanopores of solid adsorbents serves a unique alternative for on-board storing of hydrogen for transportation purposes. The key advantage of utilizing the physisorption process for hydrogen storage is the higher density values achieved with the adsorbed gas, compared to that of the compressed phase, translating into higher storage capacities at lower pressures. The necessary condition for superior adsorption is the presence of nanopores (< 7 ) which serves the most suitable environment of hydrogen adsorption. Despite numerous theoretical calculations or indirect experimental findings, there was no direct experimental result that measured the density of adsorbed hydrogen or compared the same with varying pore sizes. In the present study, we employed in-situ small angle neutron scattering (SANS) on adsorbed hydrogen over polyfurfuryl alcohol-derived activated carbon (PFAC), at room temperature and pressures up to ~200 bar, with an aim to provide for the first time direct experimental measurements of the effect of pore size and pressure on the density of the adsorbed hydrogen. SANS studies were carried out at the General-Purpose Small-Angle Neutron Scattering spectrometer, at the High Flux Isotope Reactor, at Oak Ridge National Laboratory. The measurements covered the Q-range from 0.01 to 0.8 -1, covering to pores in the range of 9 to 34 of the PFAC material. Initial studies suggested that the density of adsorbed hydrogen is higher than the bulk phase and increases with decrease in pore size. The calculated densification is higher at the lower pressure level.

Saha, Dipendu↗
DOE OSTI2020

AmeriFlux US-ASM USSL San Joaquin Valley Almond Medium Salinity

This is the AmeriFlux version of the carbon flux data for the site US-ASM USSL San Joaquin Valley Almond Medium Salinity. Site Description - almond orchard in San Joaquin Valley. Different water source and water quality than adjacent site US-SAH

Anderson, Ray G.↗
DOE OSTI2020

AmeriFlux US-xSJ NEON San Joaquin Experimental Range (SJER)

This is the AmeriFlux version of the carbon flux data for the site US-xSJ NEON San Joaquin Experimental Range (SJER). Site Description - Located at The San Joaquin Experimental Range, in the western foothills of the Sierra Nevada, this 18.2 kilometer terrestrial field site is a mix of open woodlands, shrubs and grasslands with low density cattle grazing. SJER is an ecosystem research experimental area. It was originally conceived as a cooperative interdisciplinary research center to identify cost-effect methods of commercial livestock production in the annual grass-oak pine woodlands, while maintaining the integrity of the ecosystem. More recently, research objectives have expanded and diversified to include research projects making contributions to our knowledge of the patterns and processes working in this ecosystem.

Network), NEON (National Ecological Observatory↗
DOE OSTI2024

AmeriFlux FLUXNET-1F US-ASH USSL San Joaquin Valley Almond High Salinity

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-ASH USSL San Joaquin Valley Almond High Salinity. This is the FLUXNET version of the carbon flux data for the site US-ASH USSL San Joaquin Valley Almond High Salinity produced by applying the standard ONEFlux (1F) software.

Anderson, Ray G.↗
DOE OSTI2020

Kimberlina - Regional Static 3D Geologic Model of the Southern San Joaquin Basin

Regional static 3D geologic model of the southern San Joaquin Basin for the Westcarb Kimberlina demonstration project created in Earthvision (DGI, Inc.). Also contains a smaller-scale model from the larger basin domain for the geometry used in Birkholzer et al. (2011). Data sets derived from: Wagoner, J., 2009, 3D geologic modeling of the Southern San Joaquin Basin for the Westcarb Kimberlina demonstration project—A status report: Lawrence Livermore National Laboratory LLNL-TR-410813, 27 p. Birkholzer, J.T., Zhou, Q., Cortis, A. and Finsterle, S., 2011, A sensitivity study on regional pressure buildup from large-scale CO2 storage projects. Energy Procedia, 4, pp.4371-4378. LLNL contact and file inventory creator: Kayyum Mansoor (mansoor1@llnl.gov)

3D Geological Model↗
DOE OSTI2012

Modeling the Gila-San Francisco Basin using system dynamics in support of the 2004 Arizona Water Settlement Act

Water resource management requires collaborative solutions that cross institutional and political boundaries. This work describes the development and use of a computer-based tool for assessing the impact of additional water allocation from the Gila River and the San Francisco River prescribed in the 2004 Arizona Water Settlements Act. Between 2005 and 2010, Sandia National Laboratories engaged concerned citizens, local water stakeholders, and key federal and state agencies to collaboratively create the Gila-San Francisco Decision Support Tool. Based on principles of system dynamics, the tool is founded on a hydrologic balance of surface water, groundwater, and their associated coupling between water resources and demands. The tool is fitted with a user interface to facilitate sensitivity studies of various water supply and demand scenarios. The model also projects the consumptive use of water in the region as well as the potential CUFA (Consumptive Use and Forbearance Agreement which stipulates when and where Arizona Water Settlements Act diversions can be made) diversion over a 26-year horizon. Scenarios are selected to enhance our understanding of the potential human impacts on the rivers ecological health in New Mexico; in particular, different case studies thematic to water conservation, water rights, and minimum flow are tested using the model. The impact on potential CUFA diversions, agricultural consumptive use, and surface water availability are assessed relative to the changes imposed in the scenarios. While it has been difficult to gage the acceptance level from the stakeholders, the technical information that the model provides are valuable for facilitating dialogues in the context of the new settlement.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

University of California, San Diego (UCSD) Sky Imager Cloud Position Study Field Campaign Report

During the University of California, San Diego (UCSD) Sky Imager Cloud Position Study, two University of California, San Diego Sky Imagers (USI) (Figure 1) were deployed the U.S. Department of Energy(DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains SGP) research facility. The UCSD Sky Imagers were placed 1.7 km apart to allow for stereographic determination of the cloud height for clouds over approximately 1.5 km. Images with a 180-degree field of view were captured from both systems during daylight hours every 30 seconds beginning on March 11, 2013 and ending on November 4, 2013. The spatial resolution of the images was 1,748 × 1,748, and the intensity resolution was 16 bits using a high-dynamic-range capture process. The cameras use a fisheye lens, so the images are distorted following an equisolid angle projection.

58 GEOSCIENCES↗
DOE OSTI2019

Conference Grant Report Submitted to the Office of Fusion Energy Science by the University of California, San Diego

The High Energy Density Science Association (HEDSA) in collaboration with the University of California San Diego (UCSD), hosted the High Energy-Density Science Summer School from July 30 – August 11, 2017 on the UC San Diego campus. The goal of the Summer School series is to introduce new talent to the breadth of the U.S. High Energy Density Science (HEDS) community through lectures, engaging workshops, and discussion sessions with leaders in academia and the national laboratories. The objectives are to inspire young scientists to pursue graduate and professional careers in the fields of high energy density science, teach them fundamental HED science and critical skills, and grant them the opportunity to network with leading academic and national laboratory researchers. Our focus was to attract promising early-career students from across the country.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗