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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 685 records · Page 38

All sources NASA NTRS DOE OSTI

DOE OSTI2026

Measuring Loss Tangents of Substrates for Superconducting Qubits with Part-per-Billion Precision

We report precision measurements of dielectric loss tangents in substrates for superconducting qubits using an ultra-high quality factor niobium SRF cavity operating at millikelvin temperatures and low electric fields. Multiple substrate types and surface treatments are compared to assess how processing impacts microwave dissipation. The RF results are correlated with materials analysis, including ToF-SIMS and XPS, to identify dominant loss mechanisms. This combined study links microscopic surface chemistry to macroscopic performance and provides a framework for materials-driven improvements in qubit coherence and device design.

Bafia, Daniel [Fermilab]↗

DOE OSTI2026

Measuring Loss Tangents of Substrates for Superconducting Qubits with Part-per-Billion Precision

Bafia, Daniel [Fermilab]↗

NASA NTRS1972

Sources, losses, and transport of magnetospherically trapped particles.

Trapping, pseudo-trapping, and non-trapping regions within an observed magnetospheric configuration are described. Time averaged proton and electron distributions and available data concerning the alpha particle distribution within the trapping and pseudo-trapping regions are presented. A review of the observational evidence leading to the identification of major sources, losses, and transport of magnetospherically trapped particles is given. Conclusions are summarized and additional suggestions offered on these factors for inner and outer zone protons and electrons. One general result of this review is that much is now known of source, loss, and transport processes, although specific experiments and calculations must still be done. It is shown that the inclusion of pitch angle diffusion processes within the magnetosphere significantly alters the concept of stable trapping and allows a consistent quiescent description of outer zone electrons to be formulated from energies of a few tens of kilovolts to several MeV.

Williams, D. J.↗

NASA NTRS1995

The effect of oblateness and gravity darkening on the radiation driving in winds from rapidly rotating B stars

We calculate the radiative driving force for winds around rapidly rotating oblate B stars, and we estimate the impact these forces should have on the production of a wind compressed disk. The effects of limb darkening, gravity darkening, oblateness, and an arbitrary wind velocity field are included in the computation of vector 'oblate finite disk' (OFD) factors, which depend on both radius and colatitude in the wind. The impact of limb darkening alone, with or without rotation, can increase the mass loss by as much as 10% over values computed using the standard uniformly bright spherical finite disk factor. For rapidly rotating stars, limb darkening makes 'sub-stellar' gravity darkening the dominant effect in the radial and latitudinal OFD factors, and lessens the impact of gravity darkening at other visible latitudes (nearer to the oblate limb). Thus, the radial radiative driving is generally stronger over the poles and weaker over the equator, following the gravity darkening at these latitudes. The nonradial radiative driving is considerably smaller in magnitude than the radial component, but is directed both away from the equatorial plane and in a retrograde azimuthal direction, acting to decrease the effective stellar rotation velocity. These forces thus weaken the equatorward wind compression compared to wind models computed with nonrotating finite disk factors.

Cranmer, Steven R.↗

DOE OSTI2023

An Investigation on the Pollen-Induced Soiling Losses in Utility-Scale PV Plants

Soiling, the accumulation of dust and other contaminants on the surface of photovoltaic (PV) modules, is a common factor that can negatively impact the performance of PV systems. In this study, the authors aim to analyze the impact of pollen on soiling losses in PV systems located in North Carolina, USA, particularly during the spring season. The performance data of two utility-scale PV plants was collected and analyzed using the two soiling extraction methods. Environmental data, including croplands and vegetation was also collected and analyzed to identify correlations with soiling losses. The results of the study may help improve understanding of necessary operation and maintenance activities for PV plants and provide new insights into the phenomenon of pollen deposition on PV systems.

correlation↗

DOE OSTI2020

Understanding Hailstone Temporal Variability and Contributing Factors over the U.S. Southern Great Plains

Abstract Hailstones are a natural hazard that pose a significant threat to property and are responsible for significant economic losses each year in the United States. Detailed understanding of their characteristics is essential to mitigate their impact. Identifying the dynamic and physical factors contributing to hail formation and hailstone sizes is of great importance to weather and climate prediction and policymakers. In this study, we have analyzed the temporal and spatial variabilities of severe hail occurrences over the U.S. southern Great Plains (SGP) states from 2004 to 2016 using two hail datasets: hail reports from the Storm Prediction Center and the newly developed radar-retrieved maximum expected size of hail (MESH). It is found that severe and significant severe hail occurrences have a considerable year-to-year temporal variability in the SGP region. The interannual variabilities have a strong correspondence with sea surface temperature anomalies over the northern Gulf of Mexico and there is no outlier. The year 2016 is identified as an outlier for the correlations with both El Niño–Southern Oscillation (ENSO) and aerosol loading. The correlations with ENSO and aerosol loading are not statistically robust to inclusion of the outlier 2016. Statistical analysis without the outlier 2016 shows that 1) aerosols that may be mainly from northern Mexico have the largest correlation with hail interannual variability among the three factors and 2) meteorological covariation does not significantly contribute to the high correlation. These analyses warrant further investigations of aerosol impacts on hail occurrence.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1972

Design of toroidal transformers for maximum efficiency

The design of the most efficient toroidal transformer that can be built given the frequency, volt-ampere rating, magnetic flux density, window fill factor, and materials is described. With the above all held constant and only the dimensions of the magnetic core varied, the most efficient design occurs when the copper losses equal 60 percent of the iron losses. When this criterion is followed, efficiency is only slightly dependent on design frequency and fill factor. The ratios of inside diameter to outside diameter and height to build of the magnetic core that result in transformers of maximum efficiency are computed.

Dayton, J. A., Jr.↗

DOE OSTI2021

Characterization of the indoor near-field aerosol transmission in a model commercial office building

To evaluate the exposure potential of infectious aerosols containing SARS-CoV-2 in an office building setting, synthetic test aerosols were used to experimental study airborne particle transmission in a multizone small office test building at the Oak Ridge National Laboratory. Nine measurement points in a single zone using active aerosol impactors report that the coefficient of variation of the time-averaged concentration is <10% in two campaigns and < 15% in one campaign, so a nearly well-mixed condition was noted. To understand the effect of HVAC system operation on the dynamic concentration of aerosols in office spaces, an aerosol transport model that includes factors such as outside air (OA) ratio, filtration, return air fraction, transport loss in air ducts, and particle deposition has been developed. The results of model fitting demonstrate strong agreement with experimental data. Overall, our investigation finds the return air fraction effects outweigh other mechanisms for the aerosol recirculation in this study, and the impact of air change rate (ACR) is more important than the small particle deposition for aerosol removal. Because ACR dominates the aerosol transport, the full model can be simplified to just one factor, the ACR, while maintaining an acceptable representation of the experimental data.

60 APPLIED LIFE SCIENCES↗

NASA NTRS1997

Growth hormone/IGF-I and/or resistive exercise maintains myonuclear number in hindlimb unweighted muscles

In the present study of rats, we examined the role, during 2 wk of hindlimb suspension, of growth hormone/insulin-like growth factor I (GH/IGF-I) administration and/or brief bouts of resistance exercise in ameliorating the loss of myonuclei in fibers of the soleus muscle that express type I myosin heavy chain. Hindlimb suspension resulted in a significant decrease in mean soleus wet weight that was attenuated either by exercise alone or by exercise plus GH/IGF-I treatment but was not attenuated by hormonal treatment alone. Both mean myonuclear number and mean fiber cross-sectional area (CSA) of fibers expressing type I myosin heavy chain decreased after 2 wk of suspension compared with control (134 vs. 162 myonuclei/mm and 917 vs. 2,076 micron2, respectively). Neither GH/IGF-I treatment nor exercise alone affected myonuclear number or fiber CSA, but the combination of exercise and growth-factor treatment attenuated the decrease in both variables. A significant correlation was found between mean myonuclear number and mean CSA across all groups. Thus GH/IGF-I administration and brief bouts of muscle loading had an interactive effect in attenuating the loss of myonuclei induced by chronic unloading.

NASA Center ARC↗

NASA NTRS1991

Planetological implications of mass loss from the early Sun

The element lithium is observed to be underabundant in the Sun by a factor of approx. equal to 100. To account for this depletion, Boothroyd et al. (Ap. J., in press 1991) proposed a model in which the Sun's zero-age-main-sequence mass was approx. 1.1 solar magnitude. If this is the explanation for the lithium depletion, then astronomical observations of F/G dwarfs in clusters suggest that the timescale for mass loss is approx. equal to 0.6 Gyr. Assuming this approximate timescale, the authors investigated several planetological implications of the astrophysical model.

Whitmire, D. P.↗

NASA NTRS2010

Bone Density Following Long Duration Space Flight and Recovery

At approx.12 months, Bone Mineral Density (BMD) at most sites in men remained lower than would be predicted, raising concerns for long-term bone health consequences following space flight. Additional analyses based on longer follow-up are being conducted. Although the N is too small for definitive conclusions, women had lower rates of loss at load-bearing sites of the hip and spine immediately post-flight relative to men and smaller differences between observed vs. predicted BMD at most sites, both immediately and 12 months post-flight, relative to men. The role of other exposures/risk factors need to be explored to further understand these possible gender differences in BMD loss and recovery following long-duration space flight.

Amin, Shreyasee↗

NASA NTRS2014

Fatigue in U.S. Astronauts Onboard the International Space Station: Environmental Factors, Operational Impacts, and Implementation of Countermeasures

Since 2000, US astronauts have been supporting missions up to a six month duration on the International Space Station (ISS). Crewmembers have experienced fatigue for reasons similar to military deployments. Astronauts experience psychological stressors such as heavy workloads, extended duty periods, circadian misalignment, inadequate/ineffective sleep, and loss of the environmental cues of a gravity environment. Complicating the psychological stressors are environmental factors; distracting background noise, unexpected and variable mission schedules, unfavorable thermal control, elevated CO2 levels, and an unusual sleep environment with schedules that impinge on pre‐sleep periods. Physiological contributors to poor sleep and fatigue include a cephalad fluid shift and back pain. Restful sleep is further challenged due to a lack of gravity‐related proprioceptive cues and need for restraints. The term "space fog" has been used by astronauts to describe a phenomenon of forgetfulness, slowed reaction time and transient confusion while trying to complete tasks. There is a distinct temporal correlation with arrival on the Space Station and the onset of slowed cognitive skills and a spontaneous resolution that may take up to 6 weeks. The Genesis of this phenomenon may be chronic fatigue secondary to transitioning from a planar environment to a 360deg microgravity perspective. Recently, countermeasures to improve sleep duration and quality in astronauts on the ISS have been instituted with moderate degrees of success as measured by self‐reaction time (psychomotor vigilance task testing), actigraphy, and subjective reports. Judicious use of stimulants and hypnotics, light therapy, controlled sleep periods and sleep shifting and reducing ambient CO2 levels are a few of the most promising countermeasures being used in space to improve sleep and reduce fatigue.

Scheuring, R. A.↗

DOE OSTI2026

Performance Enhancement of the Transcritical CO2 Cycle with a Near-Isothermal Liquid Piston Compression by an Ejector

This study investigates the use of an ejector in a transcritical CO2 cycle employing a near-isothermal liquid piston compressor, with the objective of mitigating refrigerant degassing in mineral oil. While the liquid piston compressor demonstrated high isothermal efficiency (˜90%), overall cycle performance was limited by CO2 degassing during chamber pressure fluctuations. A thermodynamic model was developed to compare baseline and ejector-assisted cycles, incorporating solubility correlations, entrainment ratio characteristics, and a degassing correction factor. Results indicate that the ejector increased suction pressure and reduced CO2–oil solubility variation, which improved refrigerant intake and reduced degassing losses. Despite these benefits, the ejector-assisted cycle showed a lower coefficient of performance (COP) than the baseline. Possible contributing factors include the limited marginal benefit of pressure reduction in a highly efficient isothermal compressor, reduced effectiveness of the separator due to the use of a suction-line heat exchanger in both cycles, and uncertainties in the solubility data under transient conditions. These findings suggest that degassing mitigation is essential for realizing the potential of liquid piston compression, but ejector integration alone is unlikely to enhance COP. Future work should focus on ejector optimization, improved oil–refrigerant management, introducing less-soluble working liquids, and experimental validation under realistic operating conditions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS2022

Soil Carbon Losses Reduce Soil Moisture in Global Climate Model Simulations

Most agricultural soils have experienced substantial soil organic carbon losses in time. These losses motivate recent calls to restore organic carbon in agricultural lands to improve biogeochemical cycling and for climate change mitigation. Declines in organic carbon also reduce soil infiltration and water holding capacity, which may have important effects on regional hydrology and climate. To explore the regional hydroclimate impacts of soil organic carbon changes, we conduct new global climate model experiments with NASA Goddard Institute for Space Studies ModelE that include spatially explicit soil organic carbon concentrations associated with different human land management scenarios. Compared to a “no land use” case, a year 2010 soil degradation scenario, in which organic carbon content (OCC; weight %) is reduced by a factor of ∼0.12 on average across agricultural soils, resulted in soil moisture losses between 0.5 and 1 temporal standard deviations over eastern Asia, northern Europe, and the eastern United States. In a more extreme idealized scenario where OCC is reduced uniformly by 0.66 across agricultural soils, soil moisture losses exceed one standard deviation in both hemispheres. Within the model, these soil moisture declines occur primarily due to reductions in porosity (and to a lesser extent infiltration) that overall soil water holding capacity. These results demonstrate that changes in soil organic carbon can have meaningful, large-scale effects on regional hydroclimate and should be considered in climate model evaluations and developments. Further, this also suggests that soil restoration efforts targeting the carbon cycle are likely to have additional benefits for improving drought resilience.

Atmosphere-land interaction↗

DOE OSTI2020

Equation of motion coupled-cluster cumulant approach for intrinsic losses in x-ray spectra

We present an equation of motion coupled cluster approach for calculating and understanding intrinsic inelastic losses in core level x-ray absorption spectra (XAS). The method is based on a factorization of the transition amplitude in the time-domain, which leads to a convolution of an effective one-body spectrum and the core-hole spectral function. The spectral function characterizes these losses in terms of shake-up excitations and satellites, and is calculated using a cumulant representation of the core-hole Green’s function that includes non-linear corrections. The one-body spectrum also includes orthogonality corrections that enhance the XAS at the edge.

Rehr, John J.↗

NASA NTRS2018

Risk Tolerance and Safety Culture: Minimizing the Risk of Catastrophe by Bringing the Lessons of Space Home

The Johnson Space Center has pursued integrating risk management practices and techniques throughout a large organization with an extraordinarily diverse mission. Past mission and institutional failures have been used to inform NASA's safety culture and a implement a uniform risk management environment. Basics from the loss prevention industry have influenced NASA's approach to sustaining its unique, yet aging, infrastructure. Lessons learned at NASA can augment and enhance occupational safety, health and risk management capabilities within hazardous industries. By focusing on risk informed decision-making, building a pervasive safety culture, and accommodating human factors, NASA's safety capabilities have been specifically developed to minimize the risk of loss of life and loss of mission.

Loyd, David↗

NASA NTRS2018

Risk Tolerance and Safety Culture: Minimizing the Risk of Catastrophe by Bringing the Lessons of Space Home

The Johnson Space Center has pursued integrating safety culture and risk management practices and techniques throughout a large organization with an extraordinarily diverse mission. Past mission and institutional failures have been used to inform NASA's safety culture and a implement a uniform risk management environment. Basics from the loss prevention industry have influenced NASA's approach to sustaining its unique, yet aging, infrastructure. Lessons learned at NASA can augment and enhance occupational safety, health and risk management capabilities within hazardous industries. By focusing on risk informed decision-making, building a pervasive safety culture, and accommodating human factors, NASA's safety capabilities have been specifically developed to minimize the risk of loss of life and loss of mission.

Mishap↗

DOE OSTI2025

Quantum Key Distribution Applicability to Smart Grid Cybersecurity Systems

To meet the increasing demand for electricity and to have a more reliable and resilient electric grid against conventional and extreme events, grid modernization is more crucial now than ever before. This will require the development and deployment of devices that provide advanced communication capabilities. The overall efficiency, reliability, and resilience of the smart grid will be inextricably linked to the exchange of information between these devices. Unfortunately, the increased information flow will increase the potential attack surface and introduce new vulnerabilities. While a smarter grid will depend critically on information flow, these benefits will be accrued only if that information can be protected. Nowadays, information is secured in smart grids primarily through cryptography. However, with the increasing number of sophisticated attacks as well as the increasing computational power, the security of the “classical” cryptographic algorithms is threatened. Quantum information science offers solutions to this problem, specifically quantum key distribution (QKD), which provides a means for the generation and secure distribution of symmetric cryptographic keys. The security of QKD stems ultimately from the very nature of quantum physics. In this paper, we investigate the applicability of QKD to the various smart grid sectors and specific use cases. We have identified 18 smart grid use cases of interest for QKD suitability together with 7 QKD factors used for the assessment of the various use cases. For each use case, the impact to security of the loss of confidentiality, integrity, and/or availability is specified. In addition, the suitability of QKD is assessed for each use case with respect to multiple factors.

24 POWER TRANSMISSION AND DISTRIBUTION↗