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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Antarctic ice sheet model comparison with uncurated geological constraints shows that higher spatial resolution improves deglacial reconstructions

Accurately reconstructing past changes to the shape and volume of the Antarctic ice sheet relies on the use of physically based and thus internally consistent ice sheet modeling, benchmarked against spatially limited geologic data. The challenge in model benchmarking against geologic data is diagnosing whether model-data misfits are the result of an inadequate model, inherently noisy or biased geologic data, and/or incorrect association between modeled quantities and geologic observations. In this work we address this challenge by (i) the development and use of a new model-data evaluation framework applied to an uncurated data set of geologic constraints, and (ii) nested high-spatial-resolution modeling designed to test the hypothesis that model resolution is an important limitation in matching geologic data. While previous approaches to model benchmarking employed highly curated datasets, our approach applies an automated screening and quality control algorithm to an uncurated public dataset of geochronological observations (specifically, cosmogenic-nuclide exposure-age measurements from glacial deposits in ice-free areas). This optimizes data utilization by including more geological constraints, reduces potential interpretive bias, and allows unsupervised assimilation of new data as they are collected. We also incorporate a nested model framework in which high-resolution domains are downscaled from a continent-wide ice sheet model. We highlight the application of this framework by applying these methods to a small ensemble of deglacial ice-sheet model simulations, and demonstrate that the nested approach improves the ability of model simulations to match exposure age data collected from areas of complex topography and ice flow. We develop a range of diagnostic model-data comparison metrics to provide more insight into model performance than possible from a single-valued misfit statistic, showing that different metrics capture different aspects of ice sheet deflation.

Geosciences↗
DOE OSTI2023

Understanding the cold plasma synthesis of ammonia with model metal catalysts through plasma diagnostics (Final Report)

The industrial synthesis of ammonia, which amounts to over 200 million tons annually, is the most energy-intensive chemical process. Therefore, there is a critical need and increased interest in exploring less energetic routes to produce ammonia. Not only does ammonia have a direct impact on the food market, but also it has the potential as a fuel and hydrogen carrier. Recently, plasma catalysis has emerged as a promising alternative for synthesizing ammonia at mild (pressure, temperature and power) conditions. The key to this catalytic process is the synergy between the plasma and the catalyst, where the non-equilibrium plasma allows the generation of excited species, which recombine at the catalyst surface to form ammonia. However, our current understanding of this process is in its infancy. In this respect, model metals are ideal candidates for gaining a basic understanding of this reaction. Moreover, a major roadblock to rationally designing novel effective catalysts for plasma-assisted ammonia production is the need for fundamental aspects of this process. Through a comprehensive plan that integrates model metals as catalysts and world-class diagnostics, the proposed work aims to provide fundamental knowledge about the nature of reactive processes occurring during plasma-assisted catalysis and to demonstrate the selective production of ammonia, catalyzed by employing selected metals under non-thermal plasma conditions. Toward this goal, the central thrust of this proposal was to demonstrate that the synergy between plasma and rationally selected model metals will boost ammonia yields during plasma-assisted ammonia synthesis by delaying hydrogen recombination. Specifically, we aimed to (1) understand the formation and role of gas-phase active species such as NH, N 2 , N 2 + and Ha during the plasma-enhanced synthesis of ammonia through OES and FTIRAS using different reaction configurations: a) only plasma (non-packed DBD reactor) and b) packed DBD reactor with metal nanoparticles. This proposal was awarded/recommended with a run time on the PCRF facility FY20.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2012

The Connection between Model Performance on the CCMVal Transport Diagnostics and Simulated Sensitivity of Ozone to Chlorine Change

The chemistry climate models that contributed simulations for past and future ozone evolution to the 2010 Scientific Assessment of Ozone Depletion were subject to extensive evaluation by the SPARC (Stratospheric Processes and their Role in Climate) CCMVal (Chemistry-Climate Model Validation) activity. The sensitivity of ozone to changes in composition and climate varies among the models, but the relationship between these variations and the model evaluations of CCMVal is not obvious. We have learned that the transport evaluation can be used to interpret the comparisons between observed and simulated columns of chlorine reservoirs, hydrochloric acid (HCl) and chlorine nitrate (ClONO2); these comparisons were part of the CCMVal evaluation of chemistry. The simulations with best performance on the transport diagnostics most faithfully reproduce the evolution and seasonal variation of the chlorine reservoirs as observed at NDACC (Network for Detection of Atmospheric Composition Change) stations (NyAlesund 78.9N, Kiruna 67.8N, Harestua 60.2N, Jungfraujoch 46.6N, Toronto 43.6N, Kitt Peak 31.9N, Izana 28.3N, Mauna Loa 19.5N, Lauder 45S and Arrival Heights 77.8S). In the simulations, the HCl in the lower stratosphere depends on total inorganic chlorine (Cly) and partitioning between HCl and ClON02. Total inorganic chlorine depends on the fractional release of chlorine from source gases, and ratio of ClON02 to HCl is inversely dependent on methane and varies quadratically with ozone. Simulated HCl from various models may agree with observations even though Cly is in error, partitioning is in error, or both. Simulated ozone sensitivity to chlorine is shown to be greater for models that produce larger values of chlorine nitrate for background chlorine levels, and vice versa. Comparisons with the NDACC data show why the models with 'best' transport have similar sensitivity to chlorine change. The realistic evolution of the simulated HCl and ClONO2 columns suggests realistic levels of Cly in the lower atmosphere. In addition, the wide range values for the sensitivity of ozone to chlorine obtained from the CCMVal simulations is explained by the wide range in lower atmospheric columns of ClONO2 and the concomitant wide range of levels for chlorine monoxide.

Douglass, Anne↗
NASA NTRS2012

Broadband Liner Optimization for the Source Diagnostic Test Fan

The broadband component of fan noise has grown in relevance with the utilization of increased bypass ratio and advanced fan designs. Thus, while the attenuation of fan tones remains paramount, the ability to simultaneously reduce broadband fan noise levels has become more appealing. This paper describes a broadband acoustic liner optimization study for the scale model Source Diagnostic Test fan. Specifically, in-duct attenuation predictions with a statistical fan source model are used to obtain optimum impedance spectra over a number of flow conditions for three liner locations in the bypass duct. The predicted optimum impedance information is then used with acoustic liner modeling tools to design liners aimed at producing impedance spectra that most closely match the predicted optimum values. Design selection is based on an acceptance criterion that provides the ability to apply increased weighting to specific frequencies and/or operating conditions. Typical tonal liner designs targeting single frequencies at one operating condition are first produced to provide baseline performance information. These are followed by multiple broadband design approaches culminating in a broadband liner targeting the full range of frequencies and operating conditions. The broadband liner is found to satisfy the optimum impedance objectives much better than the tonal liner designs. In addition, the broadband liner is found to provide better attenuation than the tonal designs over the full range of frequencies and operating conditions considered. Thus, the current study successfully establishes a process for the initial design and evaluation of novel broadband liner concepts for complex engine configurations.

Nark, Douglas M.↗
NASA NTRS1994

Numerical analysis and modeling of atmospheric phenomena

For the past 22 years Grant NGR 22-009-727 has been supporting research in the Center for Meteorology and Physical Oceanography (and its predecessors) in a wide variety of diagnostic and modeling studies of atmospheric and ocean phenomena. Professor Jule Charney was the initial Principal Investigator. Professor Peter Stone joined him as co-Principal Investigator in 1975 and became the sole Principal Investigator in 1981. During its lifetime the Grant has supported in whole or in part 11 Master's theses, 14 Ph.D. theses, and 45 papers published in refereed scientific journals. All of these theses and papers (with bibliographic references) are listed below. All but one of the theses were used to fulfill the requirements for MIT (Massachusetts Institute of Technology) degrees and are available from the MIT libraries. The one exception is F. Chen's Ph.D. thesis which was for a Harvard degree and is available from the Harvard libraries. In addition to the work described in the citations listed below, the Grant has supported Research Assistant Amy Solomon during the past two years to carry out a study of how baroclinic adjustment is affected by vertical resolution, vertical temperature structure, and dissipation. Ms. Solomon plans to use this project for her Ph.D. thesis. Support for this project will continue under NASA Grant NAG 5-2490, 'The Factors Controlling Poleward Heat Transport in Climate Models.'

Stone, Peter H.↗
DOE OSTI2018

High Fidelity Fast Running Multi-scale Multi-physics Battery Pack Software

The project team comprising of General Motors LLC (GM), ANSYS, ESim, and the National Renewable Energy Laboratory (NREL) proposed to develop multiscale multiphysics battery pack engineering software that significantly surpassed the most advanced state-of-the-art software in computational speed and accuracy. The successful software was to run faster than current state-of-the-art software by a factor of 100 while resolving complex multiphysics interplays across the scales from materials to large automotive battery pack systems. The proposed project was to shift the paradigm to using software for battery pack system design and evaluation, potentially revolutionizing the standard development process for the broader electric vehicle industry. The project objectives were to: (a) enhance computation speed and stability of the pack level multiscale model while still resolving nonlinearities of the battery’s dynamic responses across the scales from particles to a battery pack and (b) enhance multiphysics integrity at the pack level model enabling model-based diagnostics and prognostics for life and safety.

25 ENERGY STORAGE↗
DOE OSTI2018

Incorporating Beam Attenuation Calculations into an Integrated Data Analysis Model for Ion Effective Charge

Here, we have created a forward model for charge-exchange impurity density measurements that incorporates neutral beam attenuation measurements self-consistently for the purpose of determining the ion-effective charge Z eff . The model is constructed within an integrated data analysis framework to include a self-consistent calculation of neutral beam attenuation due to multiple impurity species into the measurement of a single impurity density. The model includes measurements of the beam Doppler-shift spectrum and shine-through particle flux to determine the neutral beam particle density which is attenuated by ion collisions. Synthetic data are generated from the diagnostic forward model using statistical and calibration uncertainties. These “noisy” data are used in the analysis to evaluate how accurately Z eff is determined. Methods of experimental design are employed to calculate the information gained from different diagnostic combinations. The analysis shows that while attenuation measurements alone do not provide a unique impurity density measurement in the case of a multispecies inhomogeneous plasma, they do provide an effective measurement of the Z eff profile and place constraints on the impurity density profiles.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1978

Earth Radiation Budget Science, 1978. 1: Introduction

An earth radiation budget satellite system (ERBSS) is planned in order to understand climate on various temporal and spatial scales. The system consists of three satellites and is designed to obtain radiation budget data from the earth's surface. Among the topics discussed are the climate modeling and climate diagnostics, the applications of radiation modeling to ERBSS, and the influence of albedo clouds on radiation budget and atmospheric circulation.

Source record↗
NASA NTRS2001

NASA IVHM Technology Experiment for X-vehicles (NITEX)

The purpose of the NASA IVHM Technology Experiment for X-vehicles (NITEX) is to advance the development of selected IVHM technologies in a flight environment and to demonstrate the potential for reusable launch vehicle ground processing savings. The technologies to be developed and demonstrated include system-level and detailed diagnostics for real-time fault detection and isolation, prognostics for fault prediction, automated maintenance planning based on diagnostic and prognostic results, and a microelectronics hardware platform. Complete flight The Evolution of Flexible Insulation as IVHM consists of advanced sensors, distributed data acquisition, data processing that includes model-based diagnostics, prognostics and vehicle autonomy for control or suggested action, and advanced data storage. Complete ground IVHM consists of evolved control room architectures, advanced applications including automated maintenance planning and automated ground support equipment. This experiment will advance the development of a subset of complete IVHM.

Sandra, Hayden↗
NASA NTRS2020

A Statistical Model to Predict the Extratropical Transition of Tropical Cyclones

This paper introduces a logistic regression model for the extratropical transition(ET) of tropical cyclones in the North Atlantic and the Western North Pacific, using elastic net regularization to select predictors and estimate coefficients.Predictors are chosen from the 1979-2017 best track and reanalysis datasets, and verification is done against the tropical/extratropical labels in the best track data. In an independent test set, the model skillfully predicts ET at lead times up to two days, with latitude and sea surface temperature as its most important predictors. At a lead time of 24 h, it predicts ET with a Matthews correlation coefficient of 0.4 in the North Atlantic, and 0.6 in the Western North Pacific. It identifies 80% of storms undergoing ET in the North Atlantic, and 92% of those in the Western North Pacific. 90% of transition time errors are less than 24 h. Select examples of the model's performance on individual storms illustrate its strengths and weaknesses.Two versions of the model are presented: an "operational model" that may provide baseline guidance for operational forecasts, and a "hazard model"that can be integrated into statistical TC risk models. As instantaneous diagnostics for tropical/extratropical status, both models' zero lead time predictions perform about as well as the widely used Cyclone Phase Space (CPS) in the Western North Pacific and better than the CPS in the North Atlantic, and predict the timings of the transitions better than CPS in both basins.

Melanie Bieli↗
NASA NTRS1984

Extreme Limb Profiles of the Sun at Far Infrared and Submillimeter Wavelengths

Limb intensity profiles at 30, 50, 100, and 200 microns, determined from Kuiper airborne observatory (KAO) observations of the occultation of the solar limb during the total eclipse of July 31, 1981, are presented. Significant but gradual limb brightening was found at the longer wavelengths consistent with the 6000 K temperature-plateau structure of the model chromospheres of Vernazza, Avrett, and Loeser. The 100 and 200 micrometers limbs are extended significantly further above the visible limb than the Vernazza, Avrett, and Loeser model predicts. These results show that the solar chromosphere is strongly perturbed from gravitational-hydrostatic equilibrium to heights as low as 1000 km. These profiles can serve as a powerful diagnostic for modeling the temperature and density of chromospheric structure free from the assumption of gravitational-hydrostatic equilibrium.

Becklin, E. E.↗
NASA NTRS1993

Diagnostic budgets of analyzed and modelled tropical plumes

Blackwell et al. successfully simulated tropical plumes in a global barotropic model valid at 200 mb. The plume evolved in response to strong equatorial convergence which simulated a surge in the Walker Circulation. The defining characteristics of simulated plumes are: a subtropical jet with southerlies emanating from the deep tropics; a tropical/mid-latitude trough to the west; a convergence/divergence dipole straddling the trough; and strong cross contour flow at the tropical base of the jet. Diagnostic budgets of vorticity, divergence, and kinetic energy are calculated to explain the evolution of the modelled plumes. Budgets describe the unforced (basic) state, forced plumes, forced cases with no plumes, and ECMWF analyzed plumes.

Mcguirk, James P.↗
DOE OSTI2013

Prominence mass supply and the cavity

A prevalent but untested paradigm is often used to describe the prominence-cavity system: the cavity is under-dense because it is evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolution of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model with diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prominence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 Å bandpass near the prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of our one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2013

Prominence Mass Supply and the Cavity

A prevalent but untested paradigm is often used to describe the prominence-cavity system; the cavity is under-dense because it it evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolutin of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model and diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prminence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 A badpass near he prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

PROMINENCES↗
DOE OSTI2020

Role of sheared E × B flow in self-organized, improved confinement states in magnetized plasmas

A great scientific success story of magnetic fusion research in the past several decades is the theoretical development and experimental testing of the process of turbulence decorrelation and stabilization by sheared E×B flow which shows that E×B shear effects are ubiquitous in magnetized plasmas. This concept of turbulence decorrelation and stabilization has the universality needed to explain the H-mode edge transport barriers seen in limiter and divertor tokamaks, stellarators, and mirror machines; the broader edge transport barrier seen in VHmode plasmas; and the core transport barriers formed in tokamaks. Similar effects are seen in linear devices. These examples of confinement improvement are of considerable physical interest; it is not often that a system self-organizes to reduce transport when an additional source of free energy is applied to it. The transport decrease associated with E×B velocity shear is also of great practical benefit to fusion research, since it contributed to substantially increased fusion yield in all DT magnetic fusion experiments conducted to date. The fundamental physics involved in transport reduction is the effect of E×B shear on the growth, radial extent, and phase correlation of turbulent eddies in the plasma. The same basic transport reduction process can be operational in various portions of the plasma because there are a number of ways to change the radial electric field Er. An important secondary theme in this area is the synergistic effect of E×B velocity shear and magnetic shear. Although the E×B velocity shear appears to have an effect on broader classes of microturbulence, magnetic shear can mitigate some potentially harmful effects of E×B velocity shear and facilitate turbulence stabilization. Our present understanding in this area is the result of a multi-decade, intertwined effort in theory, modeling and diagnostic development combined with continuing experimental investigations. These experiments have clearly demonstrated that increased E×B shear causes reductions in turbulence and transport. Finally, the experimental findings are generally consistent with the basic theoretical models although considerable work remains to be done before we have a fully predictive theory of transport in magnetized plasmas including E×B shear effects.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗