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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Dirac cosmology

The large numbers hypothesis (LNH) linking the magnitude of large dimensionless ratios in physics (on the order of 10 to the 40th power) to cosmic time is examined. The LNH is checked against evidence on 3K background radiation of the universe and the (log N, log S)-relation for radio galaxies. Earlier criticisms of LNH by Gamow and Teller are examined, and alternative hypotheses put forth by Dicke and Carter (1974) are discussed. The discussion covers: continuous (additive or multiplicative) creation of matter, the Einstein metric and the atomic metric, and general cosmological and local astronomical implications of LNH. LNH is also viewed in relation to solar evolution and pulsar physics.

Canuto, V.↗
DOE OSTI2022

Disentangling the Influences of Storm-Relative Flow and Horizontal Streamwise Vorticity on Low-Level Mesocyclones in Supercells

Sufficient low-level storm-relative flow is a necessary ingredient for sustained supercell thunderstorms and is connected to supercell updraft width. Assuming a supercell exists, the role of low-level storm-relative flow in regulating supercells’ low-level mesocyclone intensity is less clear. One possibility considered in this article is that storm-relative flow controls mesocyclone and tornado width via its modulation of overall updraft extent. This hypothesis relies on a previously postulated positive correspondence between updraft width, mesocyclone width, and tornado width. An alternative hypothesis is that mesocyclone characteristics are primarily regulated by horizontal streamwise vorticity irrespective of storm-relative flow. A matrix of supercell simulations was analyzed to address the aforementioned hypotheses, wherein horizontal streamwise vorticity and storm-relative flow were independently varied. Among these simulations, mesocyclone width and intensity were strongly correlated with horizontal streamwise vorticity, and comparatively weakly correlated with storm-relative flow, supporting the second hypothesis. Accompanying theory and trajectory analysis offers the physical explanation that, when storm-relative flow is large and updrafts are wide, vertically tilted streamwise vorticity is projected over a wider area but with a lesser average magnitude than when these parameters are small. These factors partially offset one another, degrading the correspondence of storm-relative flow with updraft circulation and rotational velocity, which are the mesocyclone attributes most closely tied to tornadoes. In conclusion, these results refute the previously purported connections between updraft width, mesocyclone width, and tornado width, and emphasize horizontal streamwise vorticity as the primary control on low-level mesocyclones in sustained supercells.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Metallurgical and mechanical characterization of ATP-5 aluminum alloys for minimizing machining distortion

ATP-5 aluminum alloy was considered as an alternative to 6061-T651 aluminum alloy to minimize machining distortion. ATP-5 is a proprietary cast alloy that is compositionally similar to 5083 aluminum and is purported to have excellent machinability, stability, and corrosion response. Dimensional stability tests, mechanical testing, chemical analysis, microstructural analysis, and fractography were completed to understand the metallurgy of the ATP-5 alloy and assess its potential as a 6061-T651 alloy alternative. Ultimately, the ATP-5 was found to retain dimensional stability issues, albeit to a lesser extent, relative to the 6061-T651 alloy. Combined with the residual cast structure observed microstructurally and lot-to-lot mechanical property variation, the alloy was deemed not suitable for a structural application. Alternative uses of ATP-5 include tooling, molds, vacuum chucks, fixtures, and jigs, where the material can shine in non-load bearing applications with a need for dimensional control and machinability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Complex Sources and Impacts on Remediation and Monitoring Approaches

Remedy selection, implementation, and coordination with tank farm activities for adjacent waste sites need to be facilitated by a technically defensible description of sources and their relative strength and temporal contributions to groundwater contamination. Detailed data describing contaminant source releases are typically not available, so source locations are highly uncertain. Furthermore, data on sources and model parameters are not readily available through direct measurements. Instead, source data are often derived by extrapolation from a few direct and/or indirect measurements, while model parameters are commonly estimated using inverse modeling or calibration methods. Because the conceptual model of sources will influence the mass and timing of the flux of contaminants to groundwater, uncertainty in the source terms should be considered. Even though a best-fit model can often be identified, it may not be the best representation of the sources given the sparse, uncertain nature of the data used for estimating source terms. To support future feasibility studies, a systematic approach is needed for identifying remediation and monitoring activities appropriate under conditions of uncertainty. In this study, an integrated assessment of alternative conceptual model elements has been examined using the B-Complex site in the Hanford Central Plateau to demonstrate how multiple sources in a waste management complex can be described to identify their relative contributions to groundwater. The heterogeneous structure of the system is modeled based on available field information on the lithological data for both the vadose zone and aquifer. The approach includes a simulation assessment and linkages to site data, with an uncertainty analysis applied to evaluate the effects of source term uncertainty on contaminant mass flux to groundwater. An integrated assessment of alternative conceptual model elements was evaluated to identify how parameter uncertainty impacts both temporal and spatial uncertainties associated with vadose zone source terms. Modeling scenarios identify important characteristics of remediation target zones to provide context for how surface barriers, in situ remedies, and water-table treatment zones can be designed to account for source dynamics. Ramifications for remediation and monitoring are discussed within the context of the source term uncertainty. The described approach facilitates systematically addressing alternative conceptual model questions in relation to remediation and monitoring and supports the remedial investigation/ feasibility study process and the remediation strategy development for the Hanford Central Plateau.

Rockhold, Mark L.↗
DOE OSTI2019

Complex Sources and Impacts on Remediation and Monitoring Approaches - 19058

Remedy selection, implementation, and coordination with tank farm activities for adjacent waste sites need to be facilitated by a technically defensible description of sources and their relative strength and temporal contributions to groundwater contamination. Detailed data describing contaminant source releases are typically not available, so source locations are highly uncertain. Furthermore, data on sources and model parameters are not readily available through direct measurements. Instead, source data are often derived by extrapolation from a few direct and/or indirect measurements, while model parameters are commonly estimated using inverse modeling or calibration methods. Because the conceptual model of sources will influence the mass and timing of the flux of contaminants to groundwater, uncertainty in the source terms should be considered. Even though a best-fit model can often be identified, it may not be the best representation of the sources given the sparse, uncertain nature of the data used for estimating source terms. To support future feasibility studies, a systematic approach is needed for identifying remediation and monitoring activities appropriate under conditions of uncertainty. In this study, an integrated assessment of alternative conceptual model elements has been examined using the B-Complex site in the Hanford Central Plateau to demonstrate how multiple sources in a waste management complex can be described to identify their relative contributions to groundwater. The heterogeneous structure of the system is modeled based on available field information on the lithological data for both the vadose zone and aquifer. The approach includes a simulation assessment and linkages to site data, with an uncertainty analysis applied to evaluate the effects of source term uncertainty on contaminant mass flux to groundwater. An integrated assessment of alternative conceptual model elements was evaluated to identify how parameter uncertainty impacts both temporal and spatial uncertainties associated with vadose zone source terms. Modeling scenarios identify important characteristics of remediation target zones to provide context for how surface barriers, in situ remedies, and water-table treatment zones can be designed to account for source dynamics. Ramifications for remediation and monitoring are discussed within the context of the source term uncertainty. The described approach facilitates systematically addressing alternative conceptual model questions in relation to remediation and monitoring and supports the remedial investigation/ feasibility study process and the remediation strategy development for the Hanford Central Plateau. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2003

Performance Testing of Thermal Interface Filler Materials in a Bolted Aluminum Interface Under Thermal/Vacuum Conditions

A thermal interface material is one of the many tools often used as part of the thermal control scheme for space-based applications. Historically, at Marshall Space Flight Center, CHO-THERM 1671 has primarily been used for applications where an interface material was deemed necessary. However, numerous alternatives have come on the market in recent years. It was decided that a number of these materials should be tested against each other to see if there were better performing alternatives. The tests were done strictly to compare the thermal performance of the materials relative to each other under repeatable conditions and do not take into consideration other design issues, such as off-gassing, electrical conduction, isolation, etc. The purpose of this Technical Memorandum is to detail the materials tested, test apparatus, procedures, and results of these tests. The results show that there are a number of better performing alternatives now available.

Glasgow, S. D.↗
DOE OSTI2021

Astrophysical and Theoretical Physics Implications from Multimessenger Neutron Star Observations

Here, the Neutron Star Interior Composition Explorer (NICER) recently measured the mass and equatorial radius of the isolated neutron star PSR J0030+0451. We use these measurements to infer the moment of inertia, the quadrupole moment, and the surface eccentricity of an isolated neutron star for the first time, using relations between these quantities that are insensitive to the unknown equation of state of supranuclear matter. We also use these results to forecast the moment of inertia of neutron star A in the double pulsar binary J0737-3039, a quantity anticipated to be directly measured in the coming decade with radio observations. Combining this information with the measurement of the tidal Love number with LIGO/Virgo observations, we propose and implement the first theory-agnostic and equation-of-state-insensitive test of general relativity. Specializing these constraints to a particular modified theory, we find that consistency with general relativity places the most stringent constraint on gravitational parity violation to date, surpassing all other previously reported bounds by 7 orders of magnitude and opens the path for a future test of general relativity with multimessenger neutron star observations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Alternative Technologies Meta Study Report

Brookhaven National Laboratory (BNL) was tasked to conduct a meta-study to assess peer-reviewed published, in-vivo murine, radiation biology studies that utilize X-ray irradiators. The study is intended to support a more general effort to facilitate the adoption of X-ray technologies to identify best practices that can be implemented by potential adopters, or those who are still unfamiliar with X-ray technology. The meta-study identified over 450 published papers in the last four years (September 2017 through August 2021). The review builds upon the more extensive meta-study published by the Draeger Report (June 2019) and facilitates a more recent assessment of methodological practices in the use of X-ray irradiators.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Alternative Technologies Adopters Outreach Survey Report

Brookhaven National Laboratory (BNL), in collaboration with Ioanna Iliopulos and Christopher Boyd (independent contractors), conducted quantitative and qualitative surveys to document views and opinions of scientists and researchers with firsthand experience operating x-ray devices for a wide range of research applications. The goal of the study was to fill critical information gaps and identify misconceptions widely held among the research community regarding the transition from Cesium-137 irradiators to x-ray devices. The survey instrument focused on three distinct yet interrelated areas that impact users' experience: operational impacts, including infrastructure needs, workflow, personnel management, and training, and regulatory compliance; research design and investigation impacts, including calibration, dosimetry, continuity of previous studies, development of new research agendas, and the outcomes for both; and funding impacts, specifically how grant sources and opportunities have responded to the transition.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1989

Hybrid propulsion technology program: Phase 1, volume 4

The use of a liquid oxidizer-solid fuel hybrid propellant combination in booster rocket motors appears extremely attractive due to the integration of the best features of liquid and solid propulsion systems. The hybrid rocket combines the high performance, clean exhaust, and safety of liquid propellant engines with the low cost and simplicity of solid propellant motors. Additionally, the hybrid rocket has unique advantages such as an inert fuel grain and a relative insensitivity to fuel grain and oxidizer injection anomalies. The advantages mark the hybrid rocket as a potential replacement or alternative for current and future solid propellant booster systems. The issues are addressed and recommendations are made concerning oxidizer feed systems, injectors, and ignition systems as related to hybrid rocket propulsion. Early in the program a baseline hybrid configuration was established in which liquid oxygen would be injected through ports in a solid fuel whose composition is based on hydroxyl terminated polybutadiene (HTPB). Liquid oxygen remained the recommended oxidizer and thus all of the injector concepts which were evaluated assumed only liquid would be used as the oxidizer.

Claflin, S. E.↗
NASA NTRS1999

Spaceflight Validation of Hzetrn Code

HZETRN is being developed as a fast deterministic radiation transport code applicable to neutrons, protons, and multiply charged ions in the space environment. It was recently applied to 50 hours of IMP8 data measured during the August 4, 1972 solar event to map the hourly exposures within the human body under several shield configurations. This calculation required only 18 hours on a VAX 4000 machine. A similar calculation using the Monte Carlo method would have required two years of dedicated computer time. The code has been benchmarked against well documented and tested Monte Carlo proton transport codes with good success. The code will allow important trade studies to be made with relative ease due to the computational speed and will be useful in assessing design alternatives in an integrated system software environment. Since there are no well tested Monte Carlo codes for HZE particles, we have been engaged in flight validation of the HZETRN results. To date we have made comparison with TEPC, CR-39, charge particle telescopes, and Bonner spheres. This broad range of detectors allows us to test a number of functions related to differing physical processes which add to the complicated radiation fields within a spacecraft or the human body, which functions can be calculated by the HZETRN code system. In the present report we will review these results.

Wilson, J. W.↗
DOE OSTI2019

Development of an Alternative Approach to Demonstrating Environmental Performance in the UK - 19354

European basic safety standards require that exposure of humans to the potentially harmful effects of ionising radiation are optimised so that they are as low as reasonably achievable, taking account of economic and societal factors. In the United Kingdom the responsibility for ensuring that exposures to humans are optimised is split between two regulatory functions. The Office of Nuclear Regulation regulates exposures to workers in all scenarios and to members of the public in the event of an accident. Environmental regulators in each of the four nations comprising the United Kingdom regulate exposures to members of the public from normal operations. Since the early 1990's, all permissions granted to nuclear sites in the UK for the discharge/disposal of radioactive waste to the environment have contained conditions requiring holders to demonstrate that they minimise the generation of radioactive waste, apply appropriate abatement and discharge/dispose of it in a way that minimises impacts on members of the public and the environment. For many years, the industry standard for providing this demonstration, which was heavily influenced by regulatory expectations and feedback, was to undertake one or a series of multi-attribute decision assessments (MADA). Wood's team of environmental specialists has been involved in undertaking such MADA studies for many years. Since the mid-2000's, our team has become increasingly aware of some of the limitations of undertaking MADA to demonstrate environmental performance for large scale new nuclear build projects and, in particular, the next generation of new nuclear power stations that are being planned and implemented in the UK. We have collaborated with the vendors of reactor technologies, the prospective/owner operators of new nuclear power stations and the developers of new facilities on existing sites to develop an alternative approach to demonstrating environmental performance. Our alternative approach comprises three main pillars which are summarised as: - Evolution - benefit from progressive improvements, operational experience and recent permitting activities. Our alternative approach uses the claim, argument, evidence approach which is commonly used for nuclear safety cases and which allows us to 'tell the story' of how environmental performance has been achieved. We have successfully deployed this approach for all new nuclear power stations proposed in the UK. - Integration - ensure that optimisation is integrated into the project programme and forms part of the 'big picture'. Our alternative approach allows environmental performance to be managed better throughout the life cycle of the project and ensures that our outputs are 'living' documents and do not 'sit on the shelf'. We have successfully demonstrated how this can be applied during rationalisation of major schemes and significant design changes on nuclear new build projects. - Opportunity - identify the best time to deliver elements of the programme. Our alternative approach aims to minimise the overall time, trouble and costs associated with demonstrating environmental performance by ensuring that decisions are made at the time when they offer greatest benefit and by minimising unnecessary rework. Our advice has helped to reduce the project costs and minimise delays associated with regulatory queries and interventions. This paper describes the journey that we have taken with our clients in developing our alternative approach to demonstrating environmental performance. We explain the UK regulatory context and explore the need for change. We present a number of case studies related to new nuclear power stations and other new facilities on existing nuclear sites that demonstrate the successful application of our alternative approach. We provide examples of how we have successfully implemented the outputs of our alternative approach into project and corporate management arrangements. Finally, we examine feedback from clients, regulators and other interested parties to propose future refinements. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Nonlinear evolution of quadratic gravity in 3 + 1 dimensions

We present a numerically stable system of ( 3 + 1 ) evolution equations for the nonlinear gravitational dynamics of quadratic-curvature corrections to General Relativity (quadratic gravity). We also report on the numerical implementation of these evolution equations. We recover a well-known linear instability and gather evidence that—aside from said instability—quadratic gravity exhibits a physically stable Ricci-flat subsector. In particular, we demonstrate that Teukolsky-wave perturbations of a Schwarzschild black hole as well as a full binary inspiral (evolved up to merger) remain Ricci flat throughout evolution. Furthermore, this suggests that, at least in vacuum, classical quadratic gravity can mimic General Relativity, even in the fully nonlinear strong-gravity regime.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Production-Ready CsPbBr3 Module Fabrication

The purpose of this SBIR was to work on evaluation, development, and testing of CsPbBr3 semiconductors for use in commercial gamma-ray detection. The overarching goal was to demonstrate the capability to fabricate functional detectors through resources available to H3D, Inc in pursuit of an alternative to CdZnTe for room-temperature semiconductor detectors. Throughout the project, CdZnTe crystals from Redlen were used as a control group to demonstrate whether the fabrication processes could produce reasonable results. The CdZnTe crystals were diced into roughly 6 mm x 6 mm x 4.5 mm pieces and electrodes were evaporated onto planar faces. In one case, pixels were patterned through a laser ablation method; in the other, a rudimentary pixel shadow-mask was fabricated, and the pixels were generated in the evaporation process. A 16 mm x 16 mm x 14 mm CsPbBr3 crystal was diced into four smaller crystals. These CsPbBr3 had electrodes applied in a similar way to the CdZnTe samples with a rudimentary mask used for pixels on the cathode. Tested CdZnTe pieces were found to generally function with reasonable, low-energy performance. CsPbBr3 crystals were found to be non-functional under forward bias with a large dark-current. A separate attempt, using reverse bias in a non-H3D, Inc test system, observed a dark current similar to previous observations, and some active pixels but no waveforms were observed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Implications of the weak gravity conjecture for tidal Love numbers of black holes

The weak gravity conjecture indicates that extremal black holes in the low-energy effective field theory should be able to decay. This criterion gives rise to nontrivial constraints on the coefficients of higher-order derivative corrections to gravity. In this paper, we investigate the tidal deformability of neutral black holes due to higher-order derivative corrections. As a proof of concept, we consider a correction of cubic order in the Riemann curvature tensor. The tidal Love numbers of neutral black holes receive leading-order corrections from higher-order derivative terms, since black holes in pure General Relativity have vanishing tidal Love number. We conclude that the interplay between the tidal deformability of black holes and the weak gravity conjecture provides useful information about the effective field theory.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2014

Development and Validation of Linear Alternator Models for the Advanced Stirling Convertor

Two models of the linear alternator of the Advanced Stirling Convertor (ASC) have been developed using the Sage 1-D modeling software package. The first model relates the piston motion to electric current by means of a motor constant. The second uses electromagnetic model components to model the magnetic circuit of the alternator. The models are tuned and validated using test data and compared against each other. Results show both models can be tuned to achieve results within 7% of ASC test data under normal operating conditions. Using Sage enables the creation of a complete ASC model to be developed and simulations completed quickly compared to more complex multi-dimensional models. These models allow for better insight into overall Stirling convertor performance, aid with Stirling power system modeling, and in the future support NASA mission planning for Stirling-based power systems.

Linear Alternators↗
NASA NTRS2015

Development and Validation of Linear Alternator Models for the Advanced Stirling Convertor

Two models of the linear alternator of the Advanced Stirling Convertor (ASC) have been developed using the Sage 1-D modeling software package. The first model relates the piston motion to electric current by means of a motor constant. The second uses electromagnetic model components to model the magnetic circuit of the alternator. The models are tuned and validated using test data and also compared against each other. Results show both models can be tuned to achieve results within 7 of ASC test data under normal operating conditions. Using Sage enables the creation of a complete ASC model to be developed and simulations completed quickly compared to more complex multi-dimensional models. These models allow for better insight into overall Stirling convertor performance, aid with Stirling power system modeling, and in the future support NASA mission planning for Stirling-based power systems.

Linear Alternators↗
DOE OSTI2018

Using spectral methods to obtain particle size information from optical data: applications to measurements from CARES 2010

Abstract. Multi-wavelength in situ aerosol extinction, absorption and scattering measurements made at two ground sites during the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are analyzed using a spectral deconvolution method that allows extraction of particle-size-related information, including the fraction of extinction produced by the fine-mode particles and the effective radius of the fine mode. The spectral deconvolution method is typically applied to analysis of remote sensing measurements. Here, its application to in situ measurements allows for comparison with more direct measurement methods and validation of the retrieval approach. Overall, the retrieved fine-mode fraction and effective radius compare well with other in situ measurements, including size distribution measurements and scattering and absorption measurements made separately for PM1 and PM10, although there were some periods during which the different methods yielded different results. One key contributor to differences between the results obtained is the alternative, spectrally based definitions of fine and coarse modes from the optical methods, relative to instruments that use a physically defined cut point. These results indicate that for campaigns where size, composition and multi-wavelength optical property measurements are made, comparison of the results can result in closure or can identify unusual circumstances. The comparison here also demonstrates that in situ multi-wavelength optical property measurements can be used to determine information about particle size distributions in situations where direct size distribution measurements are not available.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗