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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Requirements for a Moderate-Resolution Infrared Imaging Sounder (MIRIS)

The high cost of imaging and sounding from space warrants exploration of new methods for obtaining the required information, including changing the spectral band sets, employing new technologies and merging instruments. In some cases we must consider relaxation of the current capability. In others, we expect higher performance. In general our goal is to meet the VIIRS and CrIS requirements while providing the enhanced next generation capabilities: 1) Hyperspectral Imaging in the Vis/NIR bands, 2) High Spatial Resolution Sounding in the Infrared bands. The former will improve the accuracy of ocean color products, aerosols and water vapor, surface vegetation and geology. The latter will enable the high-impact achieved by the current suite of hyperspectral infrared sounders to be achieved by the next generation high resolution forecast models. We examine the spectral, spatial and radiometric requirements for a next generation system and technologies that can be applied from the available inventory within government and industry. A two-band grating spectrometer instrument called the Moderate-resolution Infrared Imaging Sounder (MIRIS) is conceived that, when used with the planned NASA PACE Ocean Color Instrument (OCI) will meet the vast majority of CrIS and VIIRS requirements in the all bands and provide the next generation capabilities desired. MIRIS resource requirements are modest and the Technology Readiness Level is high leading to the expectation that the cost and risk of MIRIS will be reasonable.

Atmospheric Infrared Sounder (AIRS)↗
NASA NTRS2018

Updates of Moderate Resolution Imaging Spectroradiometer On-Orbit Calibration Uncertainty Assessments

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments have successfully operated for more than 18 and 16 years, respectively, on-board the NASA’s Earth Observing System Terra and Aqua spacecraft. Both Terra and Aqua MODIS have significantly contributed to the advance of global Earth remote sensing applications with a broad range of science products that have been continuously produced since the beginning of each mission and freely distributed to users worldwide. MODIS collects data in 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB), covering wavelengths from 0.41 to 14.4 μm. Its level 1B (L1B) data products, which provide the input for the MODIS high-level science products, include the top of the atmosphere reflectance factors for the RSB, radiances for both the RSB and TEB, and associated uncertainty indices (UI) at a pixel-by-pixel level. This paper provides a brief review of MODIS L1B calibration algorithms, including a number of improvements made in recent years. It presents an update of sensor calibration uncertainty assessments with a focus on several new contributors resulting from on-orbit changes in sensor characteristics, approaches developed to address these changes, and the impact due to on-orbit changes on the L1B data quality. Also discussed are remaining challenges and potential improvements to be made to continuously maintain sensor calibration and data quality, particularly those related to the quality of MODIS L1B uncertainty.

Spectroradiometer↗
NASA NTRS2017

Realistic 3D Radiative Modeling of Turbulent Structure of Moderate-Mass Stars and Sun

Understanding the turbulent dynamics of the Sun and stars is a critical element for interpreting observed processes and phenomena on different scales and for predicting extreme events such as flares and super flares. High-­‐resolution observations of the Sun and high-­‐fidelity radiative MHD numerical simulations have substantially advanced our understanding of solar and stellar local dynamics and magnetism from the upper convection zone to the atmosphere and corona. However, global modeling of the Sun with such a high degree of realism is currently not affordable due to the extremely high computational cost of resolving the scales in the convection zone. The physics of the deep solar dynamics can be effectively addressed through modeling more massive solar-­‐type stars where the convection zone is shallower and the convective overturning time is much shorter than those on the Sun. We present recent 3D realistic simulation results of moderate-­‐mass stars and discuss links between solar and stellar dynamics, such as the multiscale structure of granulation, convective overshoot, and others. In particular, these simulations have provided better understanding of the dynamics of the tachocline (the overshoot layer at the bottom of the convection zone) and have explained long-­‐ standing results from helioseismology.

Realistic↗
NASA NTRS2023

Warming Overwhelms the Efficacy of Wet Conditions to Moderate Extreme Heat and Atmospheric Aridity Across the Central Plains

While the relationships between dry land surface conditions, heat, and aridity have been well-established, few studies have addressed whether global warming will affect the ability of wet conditions to moderate high temperatures and atmospheric aridity. Using Coupled Model Intercomparison Project Phase 6 models, we demonstrate that absolute changes in the monthly maximum temperature distribution during Central North American summers strongly outweigh the historical cooling effect of high precipitation and soil moisture conditions. Although wet conditions nearly always prevent concurrent extreme temperatures in the baseline period, these conditions are 40%–48% and 96%–98% less effective at 1 and 2° of global warming, respectively. However, high precipitation and soil moisture partially retain the ability to constrain concurrent high vapor pressure deficit conditions below historical thresholds at 1–2° of warming. Our results highlight the growing vulnerability of Central North America to warmer temperatures and drier atmospheric conditions, even during periods of high precipitation and soil moisture.

global warming↗
DOE OSTI2011

Design of a Moderated Multidetector Neutron Spectrometer for Optimal Specificity

Neutron spectrometry can play an important role in the detection and identification of neutron-emitting sources in various security applications. In the present work, a portable filtered array neutron spectrometer, consisting of twelve 6LiF-based thermal neutron detectors embedded within a single heterogeneous volume was designed and its expected performance compared to that of a commercially available 12-sphere Bonner spheres spectrometer. Each detector within the volume was designed to optimally respond to a unique portion of the neutron spectrum by varying the type and thickness of materials used to filter the spectrum as well as the thickness of the moderator in front of the detector. The available design space was permuted and performance metrics developed to identify the optimal geometries. The top performing detector geometries were then combinatorially explored to identify the best array of geometries that yielded the most information about a neutron spectrum. The best performing filtered array was found to provide as much spectral information as, or more than, the commercially available 12-sphere Bonner spheres spectrometer to which it was compared.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Characterization of a Polyethylene Moderated Highly Enriched Uranium System

The polyethylene interstitial materials for the Class Foils experiment are one of the teaching tools used to teach criticality safety at the National Criticality Experiments Research Center (NCERC). This set of polyethylene plates is designed to provide the optimal H/{sup 235}U ratio on the critical mass curve allowing the experiment to have the minimum amount of {sup 235}U. This makes a great teaching tool to show that either additional {sup 235}U or additional moderator would increase the critical mass. The optimal H/{sup 235}U ratio and increased hydrogen density compared to the previously used Lucite plates has reduced the critical mass by 34%, to 997.9 ± 0.65 g. The robustness of this experiment makes it ideal for hands on training. The fuel foils consist of thin highly enriched uranium (93 wt% {sup 235}U) metal foils laminated in plastic; each foil weighs approximately 68 grams. The fuel is interleaved between interstitial plates to attain a critical configuration. The critical configuration requires 14.5 fuel foils. Rossi-α experiments have been proposed as a method of benchmarking kinetics properties given by neutronics codes such as MCNP. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2026

Modulating Li + and Polysulfide Solvation with Low-Density Moderately Solvating Electrolytes for Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries show great promise as the next-generation rechargeable batteries, yet they still suffer from polysulfide shuttling and interphasial instability. Electrolyte, as the medium for ion transport and sulfur conversion, plays a crucial role in overcoming these challenges. Here, we introduce a moderately solvating electrolyte (MSE) based on low-density, low-viscosity, and nonfluorinated ether co-solvents that balances polysulfide suppression, Li metal stabilization, and redox kinetics. Through multiple solvent–solvent and solvent-ion interactions, the optimized MSE weakens Li + -solvent pairing while strengthening cation–anion interactions, thereby lowering the desolvation barrier and promoting the formation of a favorable solid–electrolyte interphase (SEI). Meanwhile, MSE limits the polysulfide dissolution but improves the accessibility of active material through better wettability and tailored solvation environment, leading to an altered sulfur deposition mechanism with β – α conversion. This approach enables a stable cycling of high-mass loading Li–S cells (> 3.5 mg cm -2 ) at both room temperature and 45 °C (where shuttling and side reactions are severer), and demonstrates a pouch cell with lean electrolyte content (4.5 µL mg s -1 ). This work highlights a practical route to develop high-performance electrolyte for Li–S cells and provides mechanistic insights into their operation.

25 ENERGY STORAGE↗
DOE OSTI2019

Methane dehydrogenation on Cu and Ni surfaces with low and moderate oxygen coverage

First-principles density functional theory calculations are carried out to evaluate energy barriers and mechanisms for the dehydrogenation reactions of CH 4 on clean and oxygen-covered surfaces of Cu (111) and Ni (111) with low and moderate oxygen coverage. In the presence of oxygen, two possible pathways have been evaluated. The more likely pathway, which is further analyzed, is that CH 4 loses an H to the surface O. Results from this pathway agree with previous findings showing that oxygen promotes CH 4 dissociation on Cu (111) and hinders that on Ni (111). In addition, our results show lower energy barriers on Cu with higher oxygen coverages up to 0.38 monolayer. However, such an increase in oxygen coverage did not show any favorable effect for CH 4 dissociation on Ni (111). Fianlly, the findings are analyzed through electronic factors revealed by charge analysis and density of states.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Gluon TMD in particle production from low to moderate x

We study the rapidity evolution of gluon transverse momentum dependent distributions appearing in processes of particle production and show how this evolution changes from small to moderate Bjorken x.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Rapidity evolution of gluon TMD from low to moderate x

In this article, we study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small $x \ll 1$ to linear evolution at moderate $x \sim 1$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Prostatic Arterial Embolization Treating Moderate-to-Severe Lower Urinary Tract Symptoms Related to Benign Prostate Hyperplasia: A Meta-Analysis

PurposeTo evaluate the clinical efficiency and safety of PAE treating moderate-to-severe LUTS related to BPH.Materials and MethodsA systematic literature search was performed using PUBMED, EMBASE, Cochrane database of systematic review, and Web of Science, up to April 2016, to identify eligible studies. The Cochrane Collaboration’s RevMan 5.3 was used to analyze the extracted data. Random- or fixed-effect model was selected to fit the pooled out heterogeneity.Results20 eligible studies were included in this meta-analysis. Synthetic data showed that there were statistically significant improvements in IPSS (MD = −13.25; 95% CI −14.81 to −11.69; P < 0.00001), QoL score (MD = −2.34; 95% CI −2.69 to −2.00, P < 0.00001), PSA level (MD = −1.33; 95% CI −1.86 to −0.80; P < 0.00001), PV (MD = −28.00; 95% CI −35.94 to −20.07; P < 0.00001), Qmax (MD = 5.51; 95% CI 4.62 to 6.40; P < 0.00001), and PVR (MD = −67.8; 95% CI −81.35 to −53.60; P < 0.00001). There was no significant difference in IIEF score (MD = 0.93; 95% CI 0.43–1.42; P = 0.07). Major complications following PAE include pain in the perineum, retropubic area, and/or urethra (9.4%), and hematuria (9.0%).ConclusionsPAE should be considered to be the very promising alternative treatment for those who do not want or cannot tolerate surgical treatment, with its benefits on IPSS, QoL score, PSA level, PV, Qmax, and PVR without affecting erectile function.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Effective shear viscosity and dynamics of suspensions of micro-swimmers from small to moderate concentrations.

Recently, there has been a number of experimental studies convincingly demonstrating that a suspension of self-propelled bacteria (microswimmers in general) may have an effective viscosity significantly smaller than the viscosity of the ambient fluid. This is in sharp contrast with suspensions of hard passive inclusions, whose presence always increases the viscosity. Here we present a 2D model for a suspension of microswimmers in a fluid and analyze it analytically in the dilute regime (no swimmer-swimmer interactions) and numerically using a Mimetic Finite Difference discretization. Our analysis shows that in the dilute regime (in the absence of rotational diffusion) the effective shear viscosity is not affected by self-propulsion. But at the moderate concentrations (due to swimmer-swimmer interactions) the effective viscosity decreases linearly as a function of the propulsion strength of the swimmers. These findings prove that (i) a physically observable decrease of viscosity for a suspension of self-propelled microswimmers can be explained purely by hydrodynamic interactions and (ii) self-propulsion and interaction of swimmers are both essential to the reduction of the effective shear viscosity. We also performed a number of numerical experiments analyzing the dynamics of swimmers resulting from pairwise interactions. The numerical results agree with the physically observed phenomena (e.g., attraction of swimmer to swimmer and swimmer to the wall). This is viewed as an additional validation of the model and the numerical scheme.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Effects of Hydrogen Redistribution at High Temperatures in Yttrium Hydride Moderator Material

We report advanced materials development, manufacturing, and modeling capabilities for innovative reactor designs support nuclear security and mission-focused science through enhanced technology for safer and more efficient and secure production of nuclear energy. The high temperature moderator material yttrium hydride poses a significant enhancement in small reactor design by thermalizing (slowing down) neutrons and decreasing the required fuel mass for a system. The research presented here supports understanding hydrogen distribution in yttrium hydride through: (1) the development of neutron-based hydrogen imaging and crystallographic characterization that allows us to understand fundamental diffraction behaviors and to observe changes in hydrogen distribution as a function of temperature and (2) subsequent neutron multiplication (reactivity) effects of changes in hydrogen distribution using measurement-based cross sections in a sample microreactor design. The main conclusions from the work are that: (1) hydrogen does not redistribute significantly below temperatures of 800°C in yttrium hydride and (2) hydrogen redistribution affects the reactivity slightly but not significantly.

36 MATERIALS SCIENCE↗