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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Nanotesla Magnetometry with the Silicon Vacancy in Silicon Carbide

Silicon carbide is a promising host material for spin-defect-based quantum sensors owing to its commercial availability and established techniques for electrical and optical microfabricated device integration. The negatively charged silicon vacancy is one of the leading spin defects studied in silicon carbide owing to its near-telecom photoemission, high spin number, and nearly temperature-independent ground-state zero-field splitting. We report the realization of nanotesla shot-noise-limited ensemble magnetometry based on optically detected magnetic resonance with the silicon vacancy in 4H silicon carbide. By coarsely optimizing the anneal parameters and minimizing power broadening, we achieve a sensitivity of 50 nT/√Hz and a theoretical shot-noise-limited sensitivity of 3.5 nT/√Hz. This is accomplished without utilizing complex photonic engineering, control protocols, or applying excitation powers greater than a watt. This work demonstrates that the silicon vacancy in silicon carbide provides a low-cost and simple approach to quantum sensing of magnetic fields.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Realization of ordered magnetic skyrmions in thin films at ambient conditions

Magnetic skyrmions have captivated physicists due to their topological nature and novel physical properties. In addition, skyrmions hold significant promise for future information technologies. A key barrier to realizing skyrmion-based devices has been stabilizing these spin structures under ambient conditions. In this paper, we demonstrate that the tunable magnetic properties of amorphous Fe/Gd mulitlayers enable the formation of skyrmion lattices which are stable over a large temperature and magnetic field parameter space, including room temperature and zero magnetic field. These skyrmions, having a hybrid nature displaying both Bloch-type and Néel-type characteristics, are stabilized by dipolar interactions rather than Dzyaloshinskii-Moriya interactions, typically considered a requirement for the generation of skyrmions. Small angle neutron scattering (SANS) was used in combination with soft x-ray microscopy to provide a unique, multiscale probe of the local and long-range order of these structures. The hexagonal lattice seen in SANS results from the hybrid skyrmion picture obtained with micromagnetic simulations. Furthermore, these results identify a pathway to engineer controllable skyrmion phases in thin film geometries which are stable at ambient conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Ewald: an extended wide-angle Laue diffractometer for the second target station of the Spallation Neutron Source

Visualizing hydrogen atoms in biological materials is one of the biggest remaining challenges in biophysical analysis. While X-ray techniques have unrivaled capacity for high-throughput structure determination, neutron diffraction is uniquely sensitive to hydrogen atom positions in crystals of biological materials and can provide a more complete picture of the atomic and electronic structures of biological macromolecules. This information can be essential in providing predictive understanding and engineering control of key biological processes, for example, in catalysis, ligand binding and light harvesting, and to guide bioengineering of enzymes and drug design. One very common and large capability gap for all neutron atomic resolution single-crystal diffractometers is the weak flux of available neutron beams, which results in limited signal-to-noise ratios giving a requirement for sample volumes of at least 0.1 mm 3 . The ability to operate on crystals an order of magnitude smaller (0.01 mm 3 ) will open up new and more complex systems to studies with neutrons which will help in our understanding of enzyme mechanisms and enable us to improve drugs against multi resistant bacteria. With this is mind, an extended wide-angle Laue diffractometer, `Ewald', has been designed, which can collect data using crystal volumes below 0.01 mm 3 .

36 MATERIALS SCIENCE↗
DOE OSTI2022

An automated approach to the alignment of compound refractive lenses

Compound refractive lenses (CRLs) are established X-ray focusing optics, and are used to focus the beam or image the sample in many beamlines at X-ray facilities. While CRLs are quite established, the stack of single lens elements affords a very small numerical aperture because of the thick lens profile, making them far more difficult to align than classical optical lenses that obey the thin-lens approximation. This means that the alignment must be very precise and is highly sensitive to changes to the incident beam, often requiring regular readjustments. Some groups circumvent the full realignment procedure by using engineering controls ( e.g. mounting optics) that sacrifice some of the beam's focusing precision, i.e. spot size, or resolution. While these choices minimize setup time, there are clear disadvantages. This work presents a new automated approach to align CRLs using a simple alignment apparatus that is easy to adapt and install at different types of X-ray experiments or facilities. This approach builds on recent CRL modeling efforts, using an approach based on the Stochastic Nelder–Mead (SNM) simplex method. This method is outlined and its efficacy is demonstrated with numerical simulation that is tested in real experiments conducted at the Advanced Photon Source to confirm its performance with a synchrotron beam. This work provides an opportunity to automate key instrumentation at X-ray facilities.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Identifying Hydrometeorological Factors Influencing Reservoir Releases Using Machine Learning Methods

Simulation of reservoir releases plays a critical role in social-economic functioning and our nation's security. How-ever, it is challenging to predict the reservoir release accurately because of many influential factors from natural environments and engineering controls such as the reservoir inflow and storage. Moreover, climate change and hydrological intensification causing the extreme precipitation and temperature make the accurate prediction of reservoir releases even more challenging. Machine learning (ML) methods have shown some successful applications in simulating reservoir releases. However, previous studies mainly used inflow and storage data as inputs and only considered their short-term influences (e.g, previous one or two days). In this work, we use long short-term memory (LSTM) networks for reservoir release prediction based on four input variables including inflow, storage, precipitation, and temperature and consider their long-term influences. We apply the LSTM model to 30 reservoirs in Upper Colorado River Basin, United States. We analyze the prediction performance using six statistical metrics. More importantly, we investigate the influence of the input hydrometeorological factors, as well as their temporal effects on reservoir release decisions. Results indicate that inflow and storage are the most influential factors but the inclusion of precipitation and temperature can further improve the prediction of release especially in low flows. Additionally, the inflow and storage have a relatively long-term effect on the release. These findings can help optimize the water resources management in the reservoirs.

Fan, Ming↗
DOE OSTI2015

SU-E-P-20: Personnel Lead Apparel Integrity Inspection: Where We Are and What We Need?

Purpose: In recent years, tremendous efforts have been devoted to radiation dose reduction, especially for patients who are directly exposed to primary radiation or receive radiopharmaceuticals. Limited efforts have been focused on those personnel who are exposed to secondary radiation while fulfilling their work responsibilities associated with diagnostic imaging and image-guided interventions. Occupational exposure is compounded in daily practice and can lead to a significant radiation dose over time. Personnel lead apparel is a well-accepted engineering control to protect healthcare workers when radiation is inevitable. The question is, do we have a nationally established program to protect personnel? This study is to investigate the lead apparel inspection programs among the USA. Methods: A series of surveys of state regulations, the University Health System Consortium, and federal regulations and regulations determined by accrediting bodies were conducted. The surveys were used to determine the current status of lead apparel programs regarding integrity inspections. Based on the survey results, a thorough program was proposed accordingly. Results: Of 50 states, seventeen states and Washington D.C. require lead apparel integrity inspections within their state regulations. Eleven of these states specify that the inspection is required on an annual basis. Two of these states require lead apron integrity checks to be performed semi-annually. Eleven out of the two hundred academic medical centers surveyed responded. The results show that the method (visually vs. fluoroscopy) used to conduct lead apparel integrity checks differ greatly amongst healthcare organizations. The FDA, EPA, CRCPD and NCRP require lead apparel integrity checks. However, the level of policies is different. A standard program is not well established and clearly there is a lack of standardization. Conclusion: A program led by legislative (state or federal government) and with specific frequency, methods, tracking and criteria is needed to ensure the integrity of personnel lead apparel.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Cyber-informed Engineering Dashboard Tool

The CIE Engineered Controls Database is a large collection of entries and stored in a json structure which makes manual analysis of entries challenging. The dashboard provides a user with a simple interface to look through the database contents.

Lampe, BenjaminR↗
DOE OSTI2020

Computationally efficient evaluation of optimum homogeneous charge compression ignition operating range with accelerated multizone engine cycle simulation

The very intensive calculations necessary to define a performance map requiring evaluation of over a hundred individual operating points can be efficiently conducted with accelerated multizone for engine cycle simulation, leading to a definition of regions of acceptable and optimum homogeneous charge compression ignition operation. Accelerated multizone for engine cycle simulation has the virtue of enabling accurate evaluation of many operating conditions based on thermal stratification data from a single fluid mechanics run at motored conditions. This is possible because thermal stratification is more sensitive to engine geometry than to operating conditions. In this article, accuracy of accelerated multizone for engine cycle simulation is demonstrated by comparison with experimental data for iso-octane homogeneous charge compression ignition operation over a broad range of lean equivalence ratios (0.14–0.28). The validated accelerated multizone for engine cycle simulation model is then applied to generating a performance map for an engine controlled by appropriately adjusting equivalence ratio and internal exhaust gas recirculation. Regions of acceptable and optimum combustion are identified. It is finally demonstrated that while indicated mean effective pressure remains low for optimum homogeneous charge compression ignition operation (1–4 bar), this is sufficient for a large fraction of typical driving in light-duty vehicles. Much driving including idle can therefore be done in homogeneous charge compression ignition mode at high efficiency and low (essentially zero) NOx and particulate matter emissions.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2016

SWiFT Software Quality Assurance Plan.

This document describes the software development practice areas and processes which contribute to the ability of SWiFT software developers to provide quality software. These processes are designed to satisfy the requirements set forth by the Sandia Software Quality Assurance Program (SSQAP). APPROVALS SWiFT Software Quality Assurance Plan (SAND2016-0765) approved by: Department Manager SWiFT Site Lead Dave Minster (6121) Date Jonathan White (6121) Date SWiFT Controls Engineer Jonathan Berg (6121) Date CHANGE HISTORY Issue Date Originator(s) Description A 2016/01/27 Jon Berg (06121) Initial release of the SWiFT Software Quality Assurance Plan

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Mesoscale Connections Summer 2017

Our challenge derives from the fact that in metals or explosives grains, interfaces and defects control engineering performance in ways that are neither amenable to continuum codes (which fail to rigorously describe the heterogeneities derived from microstructure) nor computationally tractable to first principles atomistic calculations. This is a region called the mesoscale, which stands at the frontier of our desire to translate fundamental science insights into confidence in aging system performance over the range of extreme conditions relevant in a nuclear weapon. For dynamic problems, the phenomena of interest can require extremely good temporal resolutions. A shock wave traveling at 1000 m/s (or 1 mm/μs) passes through a grain with a diameter of 1 micron in a nanosecond (10-9 sec). Thus, to observe the mesoscale phenomena—such as dislocations or phase transformations—as the shock passes, temporal resolution better than picoseconds (10-12 sec) may be needed. As we anticipate the science challenges over the next decade, experimental insights on material performance at the micron spatial scale with picosecond temporal resolution—at the mesoscale— are a clear challenge. This is a challenge fit for Los Alamos in partnership with our sister labs and academia. Mesoscale Connections will draw attention to our progress as we tackle the mesoscale challenge. We hope you like it and encourage suggestions of content you are interested in.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Technical Report for Calculations of Atmospheric Dispersion at Onsite Locations for Department of Energy Nuclear Facilities

The Department of Energy (DOE) has performed an evaluation of the technical bases for the default value for the atmospheric dispersion parameter χ/Q. This parameter appears in the calculation of radiological dose at the onsite receptor location (co-located worker at 100 meters) in safety analysis of DOE nuclear facilities. The results of the calculation are then used to determine whether safety significant engineered controls should be established to prevent and/or mitigate the event causing the release of hazardous material. An evaluation of methods for calculation of the dispersion of potential chemical releases for the purpose of estimating the chemical exposure at the co-located worker location was also performed. DOE’s evaluation consisted of: (a) a review of the regulatory basis for the default χ/Q dispersion parameter; (b) an analysis of this parameter’s sensitivity to various factors that affect the dispersion of radioactive material; and (c) performance of additional independent calculations to assess the appropriate use of the default χ/Q value.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2019

PV Cyber Security Research (Final Report)

Extensive deployment of interoperable distributed energy resources (DER) on power systems is increasing the power system cyber security attack surface. National and jurisdictional interconnection standards require DER to include a range of autonomous and commanded grid support functions which can drastically influence power quality, voltage, and bulk system frequency. This project was split into two phases. The first provided a survey and roadmap of the cybersecurity for the solar industry. The second investigated multiple PV cybersecurity research and development (R&D) concepts identified in the first phase. In the first year, the team created a roadmap for improving cybersecurity for distributed solar energy resources. This roadmap was intended to provide direction for the nation over the next five years and focused on the intersection of industry and government and recommends activities in four related areas: stakeholder engagement, cyber security research and development, standards development, and industry best practices. At the same time, the team produced a primer for DER vendors, aggregators, and grid operators to establish a common taxonomy and describe basic principles of cyber security, encryption, communication protocols, DER cyber security recommendations and requirements, and device-, aggregator-, and utility-level security best practices to ensure data confidentiality, integrity, and availability. This material was motivated by the need to assist the broader PV industry with cybersecurity resilience and describe the state-of-the-art for securing DER communications. Lastly, an adversary-based assessment of multiple PV devices was completed at the Distributed Energy Technologies Laboratory at Sandia National Laboratories to determine the status of industry cybersecurity practices. The team found multiple deficiencies in the security features of the assessed devices. In the second year, a set of recommendations was created for DER communication protocols— especially with respect to the state-of-the-art requirements in IEEE 2030.5. Additionally, several cybersecurity R&D technologies related to communications-enabled photovoltaic systems were studied to harden DER communication networks. Specifically, the team investigated (a) using software defined networking to create a moving target defense system for DER communications, and (b) engineering controls that prevent misprogramming or adversary action on DER devices/networks by disallowing setpoints that will generate unstable power system operations.

14 SOLAR ENERGY↗
DOE OSTI2018

Ammonia Remediation in Hanford WTP Liquid Secondary Waste

The Hanford Site Effluent Treatment Facility (ETF) treats aqueous waste streams; some of these waste streams have high concentrations of ammonium ion. When the WTP begins operation the ETF LSW is slated to be stabilized by grouting prior to disposal. During stabilization of such waste by grouting the pH would rise considerably, leading to the evolution of ammonia gas. Such an ammonia release would require engineering controls to assure worker and environmental safety. The primary objective of this work was to perform a parametric study of the efficacy of ammonia destruction from solution using sodium nitrite addition under varying conditions that expands upon previous work.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

High Efficiency Cost Optimized - Spark Ignited Natural Gas Engines (HECO-SING) (Final Report)

The abundance of relatively low cost natural gas in the North American market, along with energy independence, makes natural gas attractive as an alternate fuel. Natural gas also has an advantage over diesel engines in low NOx emissions production. Natural gas does however have some technical challenges in its lower efficiency due to natural gas energy content in comparison to diesel or gasoline, which is also a partial factor in its vehicle storage capacity limitations and thus driving range. In order to address these challenges, the HECO-SING (High-Efficiency Cost-Optimized, Spark Ignited Natural Gas) project was undertaken. The goal was to increase engine efficiency (fuel economy), while still meeting future emissions, in a cost effective manner. In order to achieve these goals, high dilution combustion will be used with focus on advanced ignition systems, optimized aftertreatment selection, and creative engine controls are applied.

03 NATURAL GAS↗
DOE OSTI2019

Methods for Microgrid Protection (Literature Review)

This work reviews existing conventional and non-conventional protection schemes for grid- and islanded-connected mode operations in North American microgrid projects. The protection schemes applied for the microgrid projects had different types of distributed energy resources (DERs), and integrated the hydropower/diesel generators, gas/steam/wind turbines and photovoltaic (PV) systems with energy storages. In this work, conventional protection schemes were those defined within the IEEE Standard C37.2-2008, while non-conventional schemes were those not defined within this Standard. The pros and cons of conventional and non-conventional protection schemes applied in microgrid projects were discussed in detail. The overvoltage, undervoltage and frequency elements were the most common conventional protection schemes applied in microgrid projects in North America. These protection elements were used to detect the islanded conditions and faults that could not be sensed by overcurrent relays because the small fault currents contributed by the low-inertia DERs and power-electronic sources. The directional overcurrent elements allowed to distinguish between external (grid) and internal (microgrid) faults. The adaptive protection was the most popular non-conventional protection scheme applied in microgrid projects. The adaptive protection detected if the microgrid was set in grid- or islanding-connected modes and selected the relay settings for the actual microgrid conditions to avoid relays’ misoperations. In conclusion, each microgrid project can confront different types of DERs and operation modes that require individual studies to solve their protection and control challenges, to obtain the best technical and economical solution. The protection scheme results and discussions for North American microgrid projects collected in this report provides an important information to guide protection and control engineers, designers and researchers in defining the protection methods for microgrids based on the types of DERs and grid- or islanded-connected operational modes

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Viral Fate and Transport for COVID-19 - NVBL

The NVBL Viral Fate and Transport Team includes researchers from eleven DOE national laboratories and is utilizing unique experimental facilities combined with physics-based and data-driven modeling and simulation to study the transmission, transport, and fate of SARSCoV-2. The team was focused on understanding and ultimately predicting SARS-CoV-2 viability in varied environments with the goal of rapidly informing strategies that guide the nation’s resumption of normal activities. The primary goals of this project include prioritizing administrative and engineering controls that reduce the risk of SARS-CoV-2 transmission within an enclosed environment; identifying the chemical and physical properties that influence binding of SARS-CoV-2 to common surfaces; and understanding the contribution of environmental reservoirs and conditions on transmission and resurgence of SARS-CoV-2.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Viral Fate and Transport for COVID-19

The NVBL Viral Fate and Transport Team includes researchers from eleven DOE national laboratories and is utilizing unique experimental facilities combined with physics-based and data-driven modeling and simulation to study the transmission, transport, and fate of SARSCoV-2. The team was focused on understanding and ultimately predicting SARS-CoV-2 viability in varied environments with the goal of rapidly informing strategies that guide the nation’s resumption of normal activities. The primary goals of this project include prioritizing administrative and engineering controls that reduce the risk of SARS-CoV-2 transmission within an enclosed environment; identifying the chemical and physical properties that influence binding of SARS-CoV-2 to common surfaces; and understanding the contribution of environmental reservoirs and conditions on transmission and resurgence of SARS-CoV-2.

54 ENVIRONMENTAL SCIENCES↗