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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 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

A tough and sustainable fiber-forming material from lignin and waste poly(ethylene terephthalate)

In this report we describe repurposing of recycled polyesters as a matrix for lignin-a biorefinery coproduct that is used as a solid fuel and needs to find higher value-to make sustainable high-performance thermoplastic materials. Brittle lignin oligomers, isolated from plant biomass, require a low-melting host polymer matrix to form a rigid and tough renewable material. We demonstrate controlled lignin dispersion and interfacial interactions in softened recycled polyethylene terephthalate (PET) using a simple solvent-free, melt-blending technique. To avoid lignin degradation and devolatilization during melt processing, it was thermally treated. Tall oil fatty acid was used to enable PET processability at low enough temperature to accommodate lignin without charring. Chemical analysis reveals reduction of aliphatic hydroxyl content from 2 mmol g –1 to 1.63 mmol g –1 and an increase of total phenolic hydroxyl moieties from 5.86 to 6.64 mmol g –1 and cleavage of β-O-4 ether linkages due to thermal treatment. Structural transformation of lignin macromolecules during heat treatment was further confirmed by an increase in molar mass and improved thermal stability. Interfacial interactions between lignin and PET were assessed from mechanical properties and thermal analyses. Thermal treatment not only helps to improve the stability of lignin but also slightly reduces the size of the dispersed lignin domains via favored interfacial interactions with the PET matrix. These methods improve mechanical properties of the material. Further, incorporation of lignin in the plasticized PET matrix increases the ductility in the blended products. Here, the method we discuss here utilizes industrial wastes and co-products, and it does not require solvent or toxic chemicals during the reactive extrusion process that yields complete conversion to products.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Delayed Neutron Precursor Group Parameter and Spectra Generation from Fast Fission of 235U in SCALE

Delayed neutron precursor (DNP) group data are important for modeling reactor dynamics. Although the data for individual DNPs have been developed over time, the DNP group data present in the Evaluated Nuclear Data Files (ENDF) have not been updated in the past 20 years. In this work, we use SCALE to recreate the Godiva experiment that was used to generate the original DNP group structure for fast fission of 235U. However, each DNP is modeled using up-to-date data, and the results are then converted into a newly updated group structure. This conversion uses an iterative linear least squares solver to minimize chi-squared. The approaches used in this work also enable energy spectrum generation and uncertainty tracking. The method used in this paper for fast 235U fission DNP group structure updating can be applied to different energies and fissile nuclides. Demonstration of the uncertainty tracking in reactor kinetics and dynamics simulations is shown using point reactor kinetics simulations. Results show that there are data discrepancies between the International Atomic Energy Agency database and data used in ORIGEN, which are currently being fixed. Results also show that the proposed method for group spectra generation performs well.

Seifert, Luke [University of Illinois]↗
DOE OSTI2021

Gallium Nitride Superjunction Fin Field Effect Transistor (Continued Funding Report)

The goal of this project is to develop the gallium vacancy assisted diffusion (GAID) method in GaN and apply it to demonstrate 2-terminal, 3-terminal, and large area Superjunction-enhanced modules. These devices will find use in high efficiency power conversion applications with the capability of operating at higher voltages, higher frequency, and less loss than comparable stat-of- the-art devices.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Gallium Nitride Superjunction Transistor (Continued Funding Report)

The initial goal of this project is to develop the gallium vacancy assisted diffusion (GAID) method in GaN and apply it to demonstrate 2-terminal, 3-terminal, and large area Superjunction-enhanced modules. These devices will find use in high efficiency power conversion applications with the capability of operating at higher voltages, higher frequency, and less loss than comparable stat-ofthe-art devices. The approach of this project has been to utilize simulation tools to drive diffusion experiments and inform semiconductor device fabrication processes. VASP has been relied upon to simulate first principles diffusion mechanisms while SILVACO TCAD has been utilized to understand tradeoffs of the the critical dimensions in GaN devices.

42 ENGINEERING↗
DOE OSTI2023

Development of In-Situ Chlorine Generator for Metal Purification (End of Contract Report)

It has been demonstrated that rare-earth and actinide metals can be purified via conversion to chlorides and heating to volatilize impurities. To this end, BYU has been working towards designing, building, and testing a system that incorporates the chlorine gas generation method into the chloride volatility process. The efforts made towards the project tasks listed in the Statement of Work are addressed in the following sections. Finally, a report on information related to this project that has been published or presented is addressed. By the end of the contract period, small-scale tests using LaCl 3 -CaCl 2 to generate Cl 2 had been conducted, the produced Cl 2 was successfully reacted with Ce foil to create CeCl 3 , initial designs for the large-scale apparatus were completed, and manufacturing for the large-scale apparatus had begun.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1980

Methodology for the comparative assessment of the Satellite Power System (SPS) and alternative technologies

The energy systems concerned are the satellite power system, several coal technologies, geothermal energy, fission, fusion, terrestrial solar systems, and ocean thermal energy conversion. Guidelines are suggested for the characterization of these systems, side-by-side analysis, alternative futures analysis, and integration and aggregation of data. A description of the methods for assessing the technical, economic, environmental, societal, and institutional issues surrounding the development of the selected energy technologies is presented.

Wolsko, T.↗
NASA NTRS1985

Forward and reverse transfer function model synthesis

A process for synthesizing a mathematical model for a linear mechanical system using the forward and reverse Fourier transform functions is described. The differential equation for a system model is given. The Bode conversion of the differential equation, and the frequency and time-domain optimization matching of the model to the forward and reverse transform functions using the geometric simplex method of Nelder and Mead (1965) are examined. The effect of the window function on the linear mechanical system is analyzed. The model is applied to two examples; in one the signal damps down before the end of the time window and in the second the signal has significant energy at the end of the time window.

Houghton, J. R.↗
NASA NTRS1998

Methods and apparatus for using gas and liquid phase cathodic depolarizers

The invention provides methods for using gas and liquid phase cathodic depolarizers in an electrochemical cell having a cation exchange membrane in intimate contact with the anode and cathode. The electrochemical conversion of cathodic depolarizers at the cathode lowers the cell potential necessary to achieve a desired electrochemical conversion, such as ozone evolution, at the anode. When gaseous cathodic depolarizers, such as oxygen, are used, a gas diffusion cathode having the cation exchange membrane bonded thereto is preferred. When liquid phase cathodic depolarizers are used, the cathode may be a flow-by electrode, flow-through electrode, packed-bed electrode or a fluidized-bed electrode in intimate contact with the cation exchange membrane.

Murphy, Oliver J.↗
NASA NTRSDate not supplied

Modeling Electro-Optic Frequency Comb Generation as a Pump Source for Quantum Communications

The Quantum Communications group at NASA GRC is focused on developing technologies and system architectures to enable future space-based quantum networks. High-repetition rate pulsed pump lasers are needed because the signal on the quantum channel cannot be amplified, hence entanglement generation rates can only be increased through high-rate pumping. Additionally, tunability in center frequency, pulse width, and repetition rate allows for a wider parameter space over which to optimize quantum channel frequency conversion efficiency, joint spectral engineering, and channel synchronization for high-fidelity entanglement swapping –a necessary stepping-stone towards quantum repeater development. One of the most flexible methods for high-repetition rate pulse generation is through spectral shaping–generating a frequency comb from a continuous-wave(CW)laser using electro-optic modulators (EOMs). As a result, this project focuses on analytically modeling and simulating the effects various EOMs such as phase and intensity modulators have on a CW source. Generating a tunable frequency comb as the pump source allows us to conveniently fine-tune the central frequency, repetition rate, and the spectral shape of our source to match the strict optimal parameters for any given entanglement source considered in the future. These models and simulations are to be used for comparison purposes for future experiments as well as for providing the Quantum Communications group a convenient tool to understand the effects of manipulating various parameters have on the outgoing frequency comb.

Electro-optic modulator↗
NASA NTRS2025

A Preliminary Study on the Feasibility of Large Language Models for Detecting Micro-Behaviors Among Team Members in Space Missions

Large-language models (LLMs) have been recently used for spoken language understanding (SLU) to infer meaning and semantics from speech in tasks such as speaker intent and sentiment classification. Due to being trained on large amounts of data, and their ability to understand context and relationships between words, LLMs are competent, enabling them to generalize across tasks without requiring many task-specific training samples. This research examines the feasibility of few-shot learning in LLMs for detecting subtle, brief, and possibly unconscious interactions between team members, called ``micro-behaviors," and provides insights into the appropriate design of LLMs for this task. Our data came from 5 teams participating in a 45-day mission at the US National Aeronautics and Space Administration’s (NASA) Human Exploration Research Analog (HERA). More specifically we used data collected from team interaction battery (TIB) tasks teams performed five times in-mission which comprise an average 1.5 hours of conversation data per day. Micro-behaviors were coded according to an adapted version of Smith & Griffins (2022) theoretical framework in terms of Violation (i.e., presence of valenced behavior, uplifting/positive or discouraging/negative), Intensity (i.e., force of behavior in terms of how uplifting or discouraging is the behavior), and Intent (i.e., motive of the behavior in terms of whether it was deliberate or unintentional). We explore the ability of LLMs to detect the presence and intensity of micro-behaviors. We examine employing and fine-tuning readily available LLMs (i.e., RoBERTa, DistilBERT), as well as prompting state-of-the-art sequence classification models (i.e., Llama-2, Llama-3). In a total of 13,058 conversational turns (17.8% uplifting, 3.3% discouraging, 75.76% neutral, 3.14% nulls), we compute the macro F1-score of the 3-way micro-behavior classification task (i.e., classifying among uplifting, discouraging, and neutral; 33% chance). Results indicate that the RoBERTa model achieves a F1-score of 36.2% (uplift: 43.3% precision (P), 15.1% recall (R); discourage: 20% P, 0.5% R). These results significantly improve when we augment the data via paraphrasing in the RoBERTa model, reaching a 41.2% macro F1-score (uplift: 37.7% P, 86.3% R; discourage: 3.5% P, 1.8% R). Finally, the Llama-2 model with 3-shot prompting yields 38% macro F1-score (uplift: 28.7% P, 20% R; discourage: 7.2% P, 18% R), which is slightly better compared to the RoBERTa model without data augmentation, highlighting the effectiveness of sequence classification models in detecting minority classes with a small sample size. Findings indicate that LLMs hold potential to detect subtle behaviors in conversations, which could be valuable in assessing team behavior in space exploration missions. Future studies will evaluate the performance of different LLM prompting strategies or fine-tuning methods.

Ankush Raut↗
DOE OSTI2021

BETO 2021 Peer Review - Continuous Enzymatic Hydrolysis Development (CEHD) WBS 2.4.1.101

The Continuous Enzymatic Hydrolysis Development (CEHD) project aims to reduce the cost and commercialization scale-up risks of biorefinery sugar-lignin production through development of a deployable continuous enzymatic hydrolysis (CEH) process. Through the use of external cross flow membrane filtration loops coupled to enzymatic hydrolysis (EH) reactors, pretreated biomass solids and enzymes are retained for reaction while solubilized product sugars are removed in situ, with high extents of conversion achieved through a series of reactor-membrane unit stages. The CEHD project is focused on advancing CEH as a transformational, process-intensified, lower-cost method for producing soluble clarified biomass sugars and insoluble lignin-rich streams than traditional batch enzymatic hydrolysis (BEH). The project's primary objective is to reduce the cost of CEH to be compellingly lower than conventional BEH, 10% lower in year 1 and 20% lower in year 3 (end of project). A related objective is to expand CEH's operating envelope to increase process efficiency. Through more thorough de-risking and demonstration of CEH, in conjunction with building a suite of modeling and optimization tools that allow for more facile rigorous in silico evaluation of novel CEH designs and modalities, this project intends to elevate industry interest in adopting CEH as an improvement over conventional batch processing. This project was merit reviewed in FY20. It's now in its first year of a new 3-year plan spanning FY21-FY23.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2023

Virtual Engineering of Low-Temperature Conversion

In this work, we present the development of an overarching software framework and supporting multiphysics models to simulate the end-to-end process of biomass conversion. This virtual engineering (VE) software is designed with the goal of accelerating research and development and reducing risk for market-relevant biomass conversion processes. We currently support multiple models, computing paradigms, and fidelities representing the steps of feedstock pretreatment, enzymatic hydrolysis, and bioconversion. Although this VE approach was developed to support a biomass workflow, we have designed each component in a way that allows us to easily support new domains, unit models, and feedstocks. We begin by presenting the user-facing aspects of the VE software and highlight how simulated elements are defined and linked by VE functions. We then present an overview of the high-fidelity computational fluid dynamics (CFD) models developed to support our target domain before segueing into our efforts to develop accurate and fast surrogate models, capturing the salient outcomes from the CFD simulations in a significantly less computationally demanding manner. We then present how VE calculations interface with a commercial techno-economic analysis software, Aspen Plus. We conclude by presenting VE case studies that leverage these methods and discuss how our methods can be extended to support a wide variety of accelerated biofuel commercialization pathways in the future.

biofuel↗
DOE OSTI2024

Prediction of Feasibility of Polaronic OER on (110) Surface of Rutile TiO 2

The polaronic effects at the atomic level hold paramount significance for advancing the efficacy of transition metal oxides in applications pertinent to renewable energy. The lattice–distortion mediated localization of photoexcited carriers in the form of polarons plays a pivotal role in the photocatalysis. This investigation focuses on rutile TiO 2 , an important material extensively explored for solar energy conversion in artificial photosynthesis, specifically targeting the generation of green H 2 through photoelectrochemical (PEC) H 2 O splitting. By employing Hubbard-U corrected and hybrid density functional theory (DFT) methods, we systematically probe the polaronic effects in the catalysis of oxygen evolution reaction (OER) on the (110) surface of rutile TiO 2 . Theoretical understanding of polarons within the surface, coupled with simulations of OER at distinct titanium (Ti) and oxygen (O) active sites, reveals diverse polaron formation energies within the lattice sites with strong preference for bulk and surface bridge (O b ) oxygen sites. Moreover, we provide the evidence for the facilitative role of polarons in OER. Here, we find that hole polarons situated at the equatorial oxygen sites near the Ti–active site, along with bridge site hole polarons distal from the O b active site yield a small reduction in OER overpotential by ~0.06 eV and ~0.12 eV, respectively. However, subsurface, equatorial, and bridge site hole polarons significantly reduce the Ti-active site OER overpotential by ~0.4 eV through the peroxo–type oxygen pathway. We also observe that the presence of hole polarons stabilizes the *OH, *O, and *OOH intermediate species compared to the scenario without hole polarons. Overall, this study provides a detailed mechanistic insight into polaron–mediated OER, offering a promising avenue for improving the catalytic activity of transition metal oxide-based photocatalysts catering to renewable energy requisites.

14 SOLAR ENERGY↗
NASA NTRS1979

A fast-reacting and versatile optokinetic stimulus pattern by computer graphics with application examples

A computer graphics method for the generation of horizontally moving vertical stripes which serve as stimuli for optokinetic nystagmus is presented. The pattern is generated by the successive addition of a constant in a digital register, leading to its periodic overflow. Digital to analog conversion of the register contents results in a staircase waveform, which is converted into a pattern of vertical lines on a CRT. The addition of any number to the reference buffer shifts all lines uniformly, so that the group velocity of the pattern is easily controlled. The computer controlled display allows an accurate realization of a commanded velocity profile with practically no time delay and facilitates study under conditions of variable feedback. The display software can be easily modified to limit stimulation to a selected area of the moving retina, and the method has been used to simulate central scotomata. It is pointed out that the technique, while more accurate, versatile and responsive than a rotating drum device, may be less useful in experiments requiring a wide field display.

Yasui, S.↗
DOE OSTI2023

Hardware-in-the-Loop Efficiency Analysis of Tidal Power Systems

Marine renewable energy presents an opportunity for sustainable power in areas located near and in the marine environment. In particular, tidal energy offers a consistent and reliable resource. However, tidal energy harvesting systems seeking to take advantage of this resource face challenges associated with power electronics. Power conversion electronics struggle with low efficiencies, lack of off-the-shelf options for small-scale energy harvesting systems, and limited opportunities for testing with deployed turbines. This work demonstrates a hardware-in-the-loop experimental design and methodology for characterizing efficiency of tidal turbine power electronics and control methods. The suggested method removes barriers to testing these power electronics by eliminating the need for a physical tidal turbine and generator to produce accurate harvested tidal power profiles.

tidal turbine, hardware-in-the-loop, energy conver↗
DOE OSTI2024

Zeolite‐Based Catalysts for Conversion of Oxygenated Polymer Waste by Positron Annihilation

Positron Annihilation Lifetime Spectroscopy (PALS) has been employed to investigate the catalysts HZSM-5 and MESO−Y, which play a pivotal role in catalyzing and upgrading plastics, with a primary focus on oxygenated polymers, thereby transforming existing plastic materials into simpler, higher-quality value-added products. Here, in this study, PALS was systematically compared with other complementary analytical techniques. The research outcomes have successfully demonstrated the efficacy of PALS in elucidating the morphology and topology of zeolites at micro/meso-meter scales. The first experiment focuses on H-ZSM-5 zeolite subjected to treatments involving polyurethane and polypropylene. The second experiment delves into H-ZSM-5 zeolites with varying Si/Al ratios, both before and after conversion. The third experiment investigates Y zeolites that are surfactant templated to induce meso-porosity, examining their fresh state as well as their post-conversion condition. The PALS analysis was supplemented by BET (Brunauer-Emmett-Teller) analysis and NMR (Nuclear Magnetic Resonance) spectroscopies. Notably, PALS exhibits superior sensitivity, at the sub-nanometer scale, suggesting its potential as a preferred complementary method for catalysis studies. In conclusion, the integration of PALS into the repertoire of analytical tools enhances our understanding of catalyst behavior and catalytic processes, offering valuable insights for the advancement of plastic recycling and catalysis research.

32 - ENERGY CONSERVATION, CONSUMPTION, AND UTILIZA↗
DOE OSTI2024

Amine-Assisted Ligand-Exchange Method to Enhance Photovoltaic Parameters in FAPbI3 Nanocrystal Solar Cells

Perovskite colloidal nanocrystals (PeNCs) have exceptional optoelectronic properties and phase stability, making them promising for photovoltaic applications. However, insulating ligands on PeNC surfaces limit the current density and reduce the power conversion efficiency (PCE) in PeNC solar cells (SCs). This study introduces an amine-assisted ligand-exchange (ALE) strategy using 3-phenyl-1-propylamine (3P1P) to effectively remove long ligands from PeNC films. ALE reduced long-chain ligand density without increasing the number of defect states and therefore reduced the exciton-binding energy of FAPbI3 NC films. These changes facilitated exciton dissociation and charge transport in FAPbI3 PeNC SCs. The facilitation of exciton dissociation was due to the increased magnetic dipole interaction between excitons after the ALE process. The use of ALE achieved FAPbI3 PeNC SCs that had an improved short-circuit current density of 17.98 mA/cm2 and a PCE of 15.56% with improved stability after the treatment and negligible hysteresis. This work provides new insight into engineering PeNC films.

amines↗
DOE OSTI2024

A Refined Method to Translate Solar Data Quality Assessment Flags to Estimated Measurement Uncertainty

Integrating solar resource uncertainties due to radiometer measurement performance and operational data quality assessment can provide improved estimates of economic bankability, system design performance, and compliance of solar energy conversion systems. Estimating radiometer measurement uncertainty is an established procedure consistent with recognized best practices and international guidelines. SERI QC is a robust solar data quality assessment software tool that has been in continuous use for more than three decades. This report, the fourth of six for the Data Quality and Uncertainty Integration Project, presents a refined algorithm description for software to translate solar resource data quality assessment results into estimated uncertainty values in a Solar Resource Operational Uncertainty Integrator (SROUI) application. This algorithm requires three-component solar irradiance measurements - global horizontal irradiance, direct normal irradiance, and diffuse horizontal irradiance - collected at 1- to 60-minute intervals, as described in the previous deliverables. The development of this report as Deliverable 6.4 was an iterative process that included reviews and feedback from the project team on initial drafts designed to refine how the new software could best support determining solar resource data uncertainty. The results of this effort will contribute to the final software system development by National Renewable Energy Laboratory staff.

14 SOLAR ENERGY↗