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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Evaluation and recommendations for work group integration within the Materials and Processes Lab

The goal of this study was to evaluate and make recommendations for improving the level of integration of several work groups within the Materials and Processes Lab at the Marshall Space Flight Center. This evaluation has uncovered a variety of projects that could improve the efficiency and operation of the work groups as well as the overall integration of the system. In addition, this study provides the foundation for specification of a computer integrated manufacturing test bed environment in the Materials and Processes Lab.

Farrington, Phillip A.↗
DOE OSTI2025

Next-generation electronics by co-design with chalcogenide materials

As Moore’s law approaches its limits, chalcogenides offer a promising route to next-generation computing and sensing, thanks to their topological, magnetoelectric, excitonic, and spintronic properties. Yet the same traits that make them appealing, e.g., exotic properties at monolayer thickness, clean van der Waals interfaces, and strong many-body effects, also heighten sensitivity to fabrication, hindering translation into scalable devices. Progress is further constrained by fragmented knowledge across synthesis, processing, and integration, and by the lack of systematic links between fabrication parameters and performance metrics. This Perspective examines key obstacles in controlling chalcogenide heterostructures and stresses the need for an integrated co-design framework, uniting materials growth, processing, and device architecture to accelerate practical technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Thermodynamic and experimental assessment of proton conducting solid oxide fuel cells with internal methane steam reforming

Operating proton conducting solid oxide fuel cells (H-SOFCs) with hydrocarbon as fuel remains a challenge because of the instability of the anode and electrolyte materials in a CO 2 /H 2 O-containing atmosphere and the catalytic activity and coking resistance of the anode for direct oxidation of hydrocarbons. Therefore, in this paper, the steam reforming of methane (SRM, an endothermic process) is integrated into the H-SOFCs (fuel cell process, an exothermic process) for internally converting hydrocarbon to hydrogen and increasing energy efficiency of H-SOFCs. Moreover, a proton-conducting zirconate oxide (BaZr 0.8 Y 0.2 O 3 , BZY), which is stable in a CO 2 /H 2 O-containing atmosphere, is applied as an electrolyte and anode material of H-SOFCs. The operation of BZY-based H-SOFCs with internal SRM is assessed by thermodynamic calculation and experiments for the first time. The catalytic activity and coking resistance of the Ni-BZY anode for SRM are investigated thermodynamically and experimentally. Finally, the results demonstrate that the Ni-BZY anode possesses reasonable catalytic activity as well as good coking resistance for SRM at a temperature as low as 550 °C. Then, the electrochemical performance and durability of H-SOFCs operated with internal SRM are comprehensively studied from 550 °C to 700 °C.

25 ENERGY STORAGE↗
DOE OSTI2024

Integrated top-down process and voxel-based microstructure modeling for Ti-6Al-4V in laser wire direct energy deposition process

Laser-wire metal additive manufacturing (AM) is one of the ideal direct energy deposition (DED) processes for creating large-scale parts with a medium level of complexity. However, the DED process involves complex thermal signatures and wide length scales making the fabrication of realistic AM components and part qualification often reliant on experimental trial-and-error optimization. While experimental measurements over the full volume of a part are valuable and necessary, measuring the entire area of a part is significantly laborious and practically infeasible, particularly for large parts in terms of cost and rapid qualification. Therefore, in this work, we developed an effective thermal and microstructure modeling framework based on the Johnson–Mehl-Avrami-Kolmogorov (JMAK) and Koistinen & Marburger (KM) models through a top-down approach that considers plate distortion-affected thermal profiles. A voxel-by-voxel simulation method is used to predict individual phase fractions of Ti-6Al-4 V. The predicted results were validated through detailed metallurgical measurements. A combined voxel-by-voxel approach with a sparse data reconstruction technique produced a near-perfect reconstruction of the original data. This approach anticipates a significant reduction in data points and computation time and resources. Lastly, we conclude with potential extensions of this work to other modeling efforts.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Electronic transport of titanate heterostructures and their potential as channels on (001) Si

Perovskite oxides and their heterostructures have demonstrated considerable potential for devices that require high carrier densities. These oxides are typically grown on ceramic substrates that suffer from low thermal conductivity, which limits performance under high currents, and from the limited size of substrates, which precludes large scale integration and processing. We address both of these hurdles by integrating oxide heterostructures with high carrier density 2D electron gases (2DEGs) directly on (001) Si. 2DEGs grown on Si show significant improvement of the high current performance over those grown on oxide substrates, a consequence of the higher thermal conductivity of the substrate. Hall analysis, transmission line measurements, and the conductance technique are employed for a detailed analysis of the carrier density, contact resistance, mobility, and electron drift velocities. Current densities of 10 A/cm are observed at room temperature with 2.9 × 10{sup 14} electrons/cm{sup 2} at a drift velocity exceeding 3.5 × 10{sup 5 }cm/s. These results highlight the promise of oxide 2DEGs integration on Si as channels for high electron density devices.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Fire as a fundamental ecological process: Research advances and frontiers

Fire is a powerful ecological and evolutionary force that regulates organismal traits, population sizes, species interactions, community composition, carbon and nutrient cycling and ecosystem function. It also presents a rapidly growing societal challenge, due to both increasingly destructive wildfires and fire exclusion in fire–dependent ecosystems. As an ecological process, fire integrates complex feedbacks among biological, social and geophysical processes, requiring coordination across several fields and scales of study. Here, we describe the diversity of ways in which fire operates as a fundamental ecological and evolutionary process on Earth. We explore research priorities in six categories of fire ecology: (a) characteristics of fire regimes, (b) changing fire regimes, (c) fire effects on above–ground ecology, (d) fire effects on below–ground ecology, (e) fire behaviour and (f) fire ecology modelling. We identify three emergent themes: the need to study fire across temporal scales, to assess the mechanisms underlying a variety of ecological feedbacks involving fire and to improve representation of fire in a range of modelling contexts. As fire regimes and our relationships with fire continue to change, prioritizing these research areas will facilitate understanding of the ecological causes and consequences of future fires and rethinking fire management alternatives.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Multiscale Modeling of Carbon Fiber Reinforced Polymer (CFRP) for Integrated Computational Materials Engineering Process

In this work, a multiscale modeling framework for CFRP is introduced to study hierarchical structure of CFRP. Four distinct scales are defined: nanoscale, microscale, mesoscale, and macroscale. Information at lower scales can be passed to higher scale, which is beneficial for studying effect of constituents on macroscale part’s mechanical property. This bottom-up modeling approach enables better understanding of CFRP from finest details. Current study focuses on microscale and mesoscale. Representative volume element is used at microscale and mesoscale to model material’s properties. At microscale, unidirection CFRP (UD) RVE is used to study properties of UD. The UD RVE can be modeled with different volumetric fraction to encounter non-uniform fiber distribution in CFRP part. Such consideration is important in modeling uncertainties at microscale level. Currently, we identified volumetric fraction as the only uncertainty parameters in UD RVE. To measure effective material properties of UD RVE, periodic boundary conditions (PBC) are applied to UD RVE to ensure convergence of obtained properties. Properties of UD is directly used at mesoscale woven RVE modeling, where each yarn is assumed to have same properties as UD. Within woven RVE, there can be many potential uncertainties parameters to consider for a physical modeling of CFRP. Currently, we will consider fiber misalignment within yarn and angle between wrap and weft yarns. PBC is applied to woven RVE to calculate its effective material properties. The effect of uncertainties are investigated quantitatively by Gaussian process. Preliminary results of UD and Woven study are analyzed for efficacy of the RVE modeling. This work is considered as the foundation for future multiscale modeling framework development for ICME project.

Composite, ICME, Multiscale Modeling↗
DOE OSTI2016

Resonance Parameter Adjustment Based on Integral Experiments

Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Biomass pre-extraction, hydrolysis and conversion process improvements fro an integrated biorefinery

In this project, Virdia will show that it can improve the production of sugars suitable for the conversion into advanced biofuels from a range of woods. Several biomass feedstocks (Pine wood chips & Eucalyptus wood chips) will be tested on this new integrated biorefinery platform. The resultant drop-in biodiesel can be a cost-effective petroleum-replacement that can compete with projected market prices

09 BIOMASS FUELS↗
DOE OSTI2019

Integrating Smart Plug and Process Load Controls into Energy Management Information System Platforms: A Landscaping Study

Plug and process loads (PPLs) already represent a significant fraction of total energy use in commercial buildings and their contribution is expected to increase in the future. Although plug-in devices are typically not monitored or controlled, new wireless technologies are being developed that can provide these functions. These 'smart' outlets collect data from connected devices and transmit it to cloud services for energy measurement, tracking, and control purposes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Potential Integration Between Residual Biogenic Process Resources and Green Hydrogen [Slides]

This presentation highlights previously published analysis on the use of off-gases from biomass pyrolysis processes towards energy utilities. The potential for use of pyrolysis off-gases in existing steam reformers for green hydrogen production is assessed. Impacts on various operations within a steam reforming system (with natural gas as the primary base feed) from the introduction of pyrolysis off-gases in various proportions are quantified to assess the feasibility of reusing existing industrial facilities with renewably sourced gases.

09 BIOMASS FUELS↗
NASA NTRS1978

Applications and limitations of very large-scale integration in SAR azimuth processing

The major limitation of a convolution processor designed with CCD memory chips is the inability to operate in real time except for slow aircraft speeds or coarse resolutions. Two methods of summing the products were evaluated with respect to speed, power, and space requirements. A convolution processor was designed, and the number of chips as well as the power and volume requirements were determined using 4, 6, and 8 bit data words. The processor is flexible because range samples may be traded for additional azimuth samples by altering the control signals. The processor is also modular, and additional range or azimuth may be processed by adding more cards.

Kuhler, D. G.↗
NASA NTRS1992

Perspectives on integrated modeling of transport processes in semiconductor crystal growth

The wide range of length and time scales involved in industrial scale solidification processes is demonstrated here by considering the Czochralski process for the growth of large diameter silicon crystals that become the substrate material for modern microelectronic devices. The scales range in time from microseconds to thousands of seconds and in space from microns to meters. The physics and chemistry needed to model processes on these different length scales are reviewed.

Brown, Robert A.↗