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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Morphology and mixing of black carbon particles collected in central California during the CARES field study

Aerosol absorption is strongly dependent on the internal heterogeneity (mixing state) and morphology of individual particles containing black carbon (BC) and other non-absorbing species. Here, we examine an extensive microscopic data set collected in the California Central Valley during the CARES 2010 field campaign. During a period of high photochemical activity and pollution buildup, the particle mixing state and morphology were characterized using scanning transmission X-ray microscopy (STXM) at the carbon K-edge. Observations of compacted BC core morphologies and thick organic coatings at both urban and rural sites provide evidence of the aged nature of particles, highlighting the importance of highly aged particles at urban sites during periods of high photochemical activity. Based on the observation of thick coatings and more convex BC inclusion morphology, either the aging was rapid or the contribution of fresh BC emissions at the urban site was relatively small compared to background concentrations. Most particles were observed to have the BC inclusion close to the center of the host. However, host particles containing inorganic rich inclusions had the BC inclusion closer to the edge of the particle. Furthermore, these measurements of BC morphology and mixing state provide important constraints for the morphological effects on BC optical properties expected in aged urban plumes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

A Phase-Field Study on Internal to External Oxidation Transition in High-Temperature Structural Alloys

Structural alloys applied at high temperatures rely on an external dense layer of oxide scale for protection. As some reactive alloy components are selectively oxidized internally, understanding how these dispersed metal oxide particles reach the surface to form a protective scale—the so-called internal to external oxidation transition—is crucial for designing these alloys. While the literature is replete with experimental studies on oxidation of alloys, there is a lack of computational studies in this realm due to the complex nature of coupled reaction and diffusion processes in multicomponent multi-phase alloy systems. In this work, we apply a recently developed phase-field model to simulate the oxidation processes under different compositions and nucleation scenarios to gain insights into how a continuous oxide scale can be established. The results show that while alloy composition is critical for internal to external oxidation transition, the oxide nuclei size, shape and distribution also have significant impact on the transition kinetics.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Intergalactic magnetic field studies by means of γ -ray emission from GRB 190114C

The presence of delayed GeV emission after a strong transient, such as a gamma-ray burst (GRB), in the very-high energy (VHE) E > 100 GeV band can be the signature of a nonzero magnetic field in the intergalactic medium. Here we used a synchrotron self-Compton multiwavelength model to infer an analytical description of the intrinsic VHE spectrum (corrected for absorption by the extragalactic background light) of GRB 190114C to predict the light curves and spectral energy distributions of the delayed emission with Monte Carlo simulations for different intergalactic magnetic field (IGMF) configurations (strengths B = 8 × 10 -21 G, 10 -20 G, 3 × 10 -20 G and correlation length $\lambda$ > 1 Mpc), and compared them with the Fermi Large Area Telescope (Fermi LAT) limits computed for several exposure times. We found that the Fermi LAT is not sensitive enough to constrain any IGMF strengths using GRB 190114C.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Quantum ghost imaging microscopy depth-of-field study

Quantum ghost imaging approaches have been proposed to enhance biological microscopy, for example, using 2D visible detectors to provide IR images or providing additional dimensions of spatial or spectral information. Toward the goal of making such imaging schemes practical, we compare image quality and depth-of-field between traditional images and ghost images at the same excitation levels. We measure how image quality and depth-of-field depend on the parameters of the entangled light produced using type-I spontaneous parametric down-conversion (SPDC). We use a pair of time-synchronized, photon-timing single-photon avalanche diode (SPAD) array detectors to capture two distinct microscope imaging paths simultaneously on a photon-pair-by-photon-pair basis: one in a traditional imaging pathway and the other a quantum ghost imaging pathway. We calculate the depth-of-field, resolution, contrast, and signal-to-noise ratio (SNR) through the parameter space of a β-Barium Borate (BBO) type-I bulk non-linear crystal length and angle. Our results provide a basis for choosing parameters for quantum ghost imaging with type-I SPDC sources.

47 OTHER INSTRUMENTATION↗
NASA NTRS1987

Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies

The Garlock and Death Valley fault zones in SE California are two active strike-slip faults coming together on the east side of the Avawatz Mtns. The kinematics of this intersection, and the possible continuation of either fault zone, are being investigated using a combination of field mapping, and processing and interpretation of remotely sensed image data. Regional and local relationships are derivable from Thematic Mapper data (30 m resolution), including discrimination and relative age dating of alluvial fans, bedrock mapping, and fault mapping. Aircraft data provide higher spatial resolution over more limited areas. Hypotheses being considered are: (1) the Garlock fault extends east of the intersection; (2) the Garlock fault terminates at the intersection and the Death Valley fault continues southeastward; and (3) the Garlock fault has been offset right laterally by the Death Valley fault which continues to the southeast. Preliminary work indicates that the first hypothesis is invalid. From kinematic considerations, image analysis, and field work the third hypothesis is favored. The projected continuation of the Death Valley zone defines the boundary between the Mojave crustal block and the Basin and Range block.

Abrams, Michael↗
DOE OSTI2017

Alabama Residential Energy Code Field Study: Baseline Report

A research project in the state of Alabama identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in March 2014 and continued through May 2014. During this period, research teams visited 134 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates nearly $1.3 million in potential savings to Alabama homeowners that could result from increased code compliance. Public and private entities within the state can use this information to justify and catalyze future investments in energy code training and related energy-efficiency programs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Arkansas Residential Energy Code Field Study (Baseline Report)

A research project in the State of Arkansas identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in May 2015 and continued through October 2015. During this period, research teams visited 226 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $300,000 in potential annual savings to Arkansas homeowners that could result from increased code compliance.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Georgia Residential Energy Code Field Study: Baseline Report

A research project in the State of Georgia identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in April 2015 and continued through November 2015. During this period, research teams visited 216 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $3 million in potential annual savings to Georgia homeowners that could result from increased code compliance.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Kentucky Residential Energy Code Field Study: Baseline Report

A research project in the Commonwealth of Kentucky identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in April 2015 and continued through August 2015. During this period, research teams visited 140 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $1,200,000 in potential annual savings to Kentucky homeowners that could result from increased code compliance.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

Maryland Residential Energy Code Field Study: Baseline Report

A research project in the state of Maryland investigated energy code-related aspects of residential single-family new construction. The study was initiated in January 2015 and continued through July 2015. During this period, research teams visited 207 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $1.5 million in potential savings to Maryland homeowners that could result from increased code compliance. Public and private entities within the state can use this information to justify and catalyze future investments in energy code training and related energy-efficiency programs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

North Carolina Residential Energy Code Field Study: Baseline Report

A research project in the State of North Carolina identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in January 2015 and continued through September 2015. During this period, research teams visited 249 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $1.5 million in potential annual savings to North Carolina homeowners that could result from increased code compliance.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Pennsylvania Residential Energy Code Field Study: Baseline Report

A research project in the Commonwealth of Pennsylvania identified opportunities to reduce homeowner utility bills in residential single-family new construction by increasing compliance with the state energy code. The study was initiated in October 2014 and continued through July 2015. During this period, research teams visited 171 homes during various stages of construction, resulting in a substantial data set based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes, and indicates over $2.7 million in potential annual savings to Pennsylvania homeowners that could result from increased compliance with the 2009 International Energy Conservation Code (and equivalent compliance options). Public and private entities within the state can use this information to justify and catalyze future investments in energy code training and related energy-efficiency programs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Spin fluctuations, absence of magnetic order, and crystal electric field studies in the Yb 3+ -based triangular lattice antiferromagnet Rb 3 ⁢Yb⁢(VO 4 ) 2

Here, we report a comprehensive experimental investigation of the structural, thermodynamic, static, and dynamic properties of a triangular lattice antiferromagnet Rb 3 ⁢Yb(VO 4 ) 2 . Through the analysis of magnetic susceptibility, magnetization, and specific heat, complemented by crystal electric field (CEF) calculations, we confirm the Kramers' doublet with effective spin 𝐽 eff = 1/2 ground state. Magnetic susceptibility and isothermal magnetization analysis reveal a weak antiferromagnetic interaction among the 𝐽 eff = 1/2 spins, characterized by a small Curie-Weiss temperature (𝜃$^{\textrm{LT}}_{\textrm{CW}}$ ≃−0.26 K) or a reduced exchange coupling (𝐽/𝑘 B ≃ 0.18 K). The 51 V NMR spectra and spin-lattice relaxation rate (1/𝑇 1 ) show no evidence of magnetic long-range-order down to 1.6 K but reflect strong influence of CEF excitations in the intermediate temperatures. At low temperatures, 1/𝑇 1 ⁡(𝑇) shows pronounced frequency dependence and 1/𝑇 1 vs field at different temperatures follows the scaling behavior, highlighting the role of paramagnetic fluctuations. The CEF calculations using the point charge approximation divulge a large energy gap ( ∼18.61 meV) between the lowest and second lowest energy doublets, further establishing Kramers' doublet as the ground state. Our calculations also reproduce the experimental magnetization and specific heat data and indicate an in-plane magnetic anisotropy. These findings position Rb 3⁢ Yb(VO 4 ) 2 as an ideal candidate to explore intrinsic quantum fluctuations and possible quantum spin-liquid physics in a Yb 3+ -based triangular lattice antiferromagnet.

Sebastian, Sebin J. [Indian Institute of Science E↗
DOE OSTI2019

Idaho Residential Energy Code Field Study

A research project in the state of Idaho identified opportunities to reduce homeowner energy costs in residential single-family new construction by increasing compliance with the current state energy code. The study was initiated in January 2018; data collection began in March 2018 and continued through June 2018. During this period, research teams visited 127 homes during various stages of construction, resulting in a collection of data based on observations made directly in the field. Analysis of the data has led to a better understanding of the energy features present in homes and indicates nearly $500,000 in potential annual savings to Idaho homeowners that could result from increased compliance with the Idaho Energy Conservation Code.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

CalWater Field Studies Designed to Quantify the Roles of Atmospheric Rivers and Aerosols in Modulating U.S. West Coast Precipitation in a Changing Climate

The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region’s economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (AR), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions.To address these gaps a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009-2011 a series of field campaigns (CalWater 1) collected atmospheric chemistry, cloud microphysics and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on remaining gaps, a vision was developed to extend these studies offshore over the Eastern North Pacific and to enhance land based measurements from 2014-2018 (CalWater 2). The data set and selected results from CalWater 1 are summarized here. The goals of CalWater-2, and measurements to date, are then described. Through this work, CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Formation and self-organization of void superlattices under irradiation: A phase field study

Self-organized patterns, realized in non-equilibrium processes, have been widely observed in physics and chemistry. As a powerful tool to create far-from-equilibrium environments, irradiation produces a variety of types of defects, which can self-organize through physical interactions and chemical reactions. Such a process becomes complicated especially when both thermodynamics and kinetics play critical roles in pattern formation. Here, we explore the formation and self-organization mechanism of void superlattices in metals and alloys under irradiation through phase field modeling and simulations. For the first time, three different formation mechanisms of void superlattices are clearly distinguished according to their thermodynamic origin and reaction kinetics. It is discovered that the characteristic length and symmetry of an emerging superlattice is determined by the interplay of the thermodynamic driving force and the kinetic anisotropy of the system. Through parametric study, the effects of kinetic coefficients, such as atomic mobility and irradiation dose rate, on the nucleation, growth, coarsening, coalescence, and ordering of voids are systematically investigated. The theoretical model developed in this work may provide guidelines for designing desired self-organized microstructures under irradiation.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Magnetic field studies of the solar wind interaction with Venus from the Galileo flyby

During the February 10, 1990 flyby of Venus, the Galileo spacecraft skimmed the downnstream flank of the planetary bow shock. This provided an opportunity to examine both the global and the local structure of the shock in an interval during which conditions in the solar wind plasma were quite steady. The data show that the cross section of the shock in planes transverse to the flow is smaller in directions aligned with the projection of the interplanetary magnetic field than in directions not so aligned. Ultralow-frequency waves were present in the unshocked solar wind, and their amplitude peaked when the spacecraft was downstream of the foreshock. At large distances down the tail, the Mach number of the flow normal to the shock is low, thus providing the opportunity to study repeated crossings of the collisionless shock in an interesting parameter regime. Some of the shock crossings reveal structure that comes close to the theoretically predicted form of intermediate shocks, whose existence in collisionless plasmas has not been confirmed.

Kivelson, M. G.↗