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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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Conceptual Model Update of Mercury Sources and Flux at Y-12 and Upper East Fork Poplar Creek, Oak Ridge,Tennessee

The interactions between the key processes that control the fate and transport of mercury (Hg) in the sediments, groundwater, and stream water within the Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee are complex, and many aspects are not well understood. In contaminated environments such as Y-12, conceptual models are frequently developed to aid in visualizing and understanding the dynamic nature of the hydrologic, geochemical, and physical environment. These conceptual models integrate data in an internally consistent manner to understand processes that control the fate and transport of contaminants. Over the past few decades of environmental investigation at Y-12, a number of conceptual models have been developed to identify and define various technical processes at various scales. The main purpose of the activities described in this report is to update the 2011 conceptual model for Upper East Fork Poplar Creek using the most recent Hg concentration and flux data and informed scientific interpretation. Emphasis was placed on improving the previous model by implementing a more detailed spatial and temporal approach to visualize transport pathways in the watershed and trends in flux and concentration over time, and to compare baseflow and stormflow system dynamics. Detailed descriptions of historical and current Hg sources and transport pathways are also provided for the east and west ends of the facility. This conceptual model will allow the US Department of Energy to evaluate past and present remedial activities and provide a strong technical basis for prioritizing and optimizing remedial responses in a cost-effective and efficient manner. Twenty years ago, Hg flux from Outfall (OF) 200 at the headwaters of East Fork Poplar Creek represented approximately 20% of the overall flux leaving Y-12. By the time of the 2011 conceptual model report, that percentage had increased to 70%–80%. Flux estimates compiled for this report using data from 2009 to 2018 show that OF200 accounted for roughly 60% of the flux leaving Y-12. The relative role of the four storm drain conduits to OF200 appeared similar to 2011, with OF163 being the greatest contributor to downstream flux. An increase in Hg concentrations and flux occurred throughout and downstream of west end storm drains in 2011 in response to a storm drain cleanout. Leading up to the 2011 storm drain cleanout, annual baseflow flux was higher at OF200A6 than at Station 17. From 2011 to 2018, the trend reversed with concentrations and flux being higher at Station 17 than at OF200A6. A spike in concentrations occurred in July 2018, potentially due to a one-time influx of Hg that occurred during COLEX decontamination and decommissioning activities at Y-12. This report includes recommendations for improving our conceptual understanding of Hg sources, transport pathways, and flux at Y-12. Important recommendations include further evaluation of transport pathways, concurrent measurement of Hg concentration and flux under baseflow and stormflow conditions at multiple sites, and research to understand the connections among periphyton and methylmercury concentration, bioavailability, and bioaccumulation. Ongoing facility decontamination and decommissioning efforts, site characterization, remedial actions, and research are facilitating the collection of new Hg data at Y-12. The conceptual model update provided herein takes advantage of the extensive recent Hg sampling to provide an updated assessment of Hg mass balance and support a refined understanding of Hg behavior at or near Y-12. This assessment should assist in future environmental management decisions and in mitigating the impacts of Hg on the surrounding environment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Directed Energy Deposition Process Modeling, Validation, and Process-Informed Optimization

The directed energy deposition (DED) process, one of the most popular additive manufacturing techniques in use today, involves various complex physical mechanisms that are not yet well understood. In this regard, computational tools show promise for elucidating the manufacturing process and enabling nondestructive performance evaluations of manufactured parts. To better control and optimize the DED process?thereby improving the manufactured product? the present work develops and demonstrates a novel artificial intelligence (AI)-based process control and optimization technique. Specifically, a geometry-free thermo-mechanical model with adaptive subdomain construction is developed to accurately capture the material?s thermo-mechanical response under cyclical reheating and high cooling rates [1]. The model is demonstrated and validated with experimental measurements, in light of various geometries and processing parameters. Moreover, based on this thermo-mechanical model, a physics-informed reduced-order model is developed to enable quick predictions of the temperature field at every time step. Furthermore, an AI-based controller is developed that can adapt to the ever-changing system states by automatically adjusting the manufacturing process parameters. This entire work is based on the open-source Multiphysics Object-Oriented Simulation Environment (MOOSE) [2] and its recent integration with Libtorch (the C++ frontend of PyTorch [3]). The combined development of the adaptive material deposition scheme, thermo-mechanical model, associated reduced-order model, and AI-based process controller carries great potential for improving advanced manufacturing processes.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Conceptual Model of Primary Mercury Sources, Transport Pathways, and Flux at the Y-12 Complex and Upper East Fork Poplar Creek, Oak Ridge, Tennessee

The interactions between the key processes that control the fate and transport of mercury in the sediments, groundwater, and stream water within the Y-12 National Security Complex in Oak Ridge, Tennessee are extremely complicated, and many aspects are not well understood. In complex environments such as that at the Y-12 Complex, conceptual models are frequently developed to aid in visualization and understanding of the dynamic nature of the hydrologic, geochemical, and physical environment. These conceptual models represent the attempt of scientists to integrate known data in an internally consistent manner to understand processes that control the fate and transport of contaminants. Over the many years of environmental investigation at Y-12, a number of conceptual models have been developed to identify and define various technical processes at a variety of scales. Many of these models have value today as a historical summary of previous modeling efforts and are provided in Appendix A of this report. The main purpose of the activity described in this report was to develop a conceptual model that delineates the location of mercury sources, transport pathways, and flux based on the most recent data and knowledgeable scientific interpretation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

A novel role for the nuclear localization signal in regulating hnRNP K protein stability in vivo

hnRNP K is a highly conserved nucleocytoplasmic shuttling protein, which associates with RNAs through synergistic binding via its three KH domains. hnRNP K is required for proper nuclear export and translational control of its mRNA targets, and these processes are controlled by hnRNP K's movement between subcellular compartments. Whereas the nuclear export and localization of hnRNP K that is associated with mRNP complexes has been well studied, the trafficking of hnRNP K that is unbound to mRNA has yet to be elucidated. To that end, we expressed an EGFP-tagged RNA binding-defective form of hnRNP K in intact Xenopus embryos, and found it was rapidly degraded in vivo. Deleting hnRNP K's nuclear localization signal (NLS), which contains two prospective ubiquitination sites, rescued the protein from degradation. These data demonstrate a novel activity for the NLS of hnRNP K in regulating the protein's stability in vivo when it is unbound to nucleic acids. - Highlights: • An RNA-binding mutant of Xenopus hnRNP K is degraded in vivo. • hnRNP K's nuclear localization signal contains two predicted ubiquitination sites. • Deletion of the nuclear localization signal rescues RNA-binding mutant degradation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Chapter 6: Wind Turbine Control Design

In this chapter, the author introduced wind turbine control, discussing sensors and actuators, operating regions, and the operational controller loops. The author then described the different levels of models needed in the controller development process, emphasizing that the models needed for control design are a simplification of the detailed models used in control simulation testing. Scripts used in conjunction with MATLAB are used to synthesize the controller, and detailed models are used for controller simulations. We described the design of the basic operational controller based on simplified models, including the generator torque controller for optimizing energy capture, and the blade pitch controller for regulating turbine speed (or power). The author described how to account for the effects of turbine nonlinearities and actuator dynamics and saturation. We then gave an overview of modern state-space control design methods, which are useful when designing a controller to meet multiple control objectives. The author also described a variety of advanced multivariable control methods. The author gave an overview of the use of advanced sensors (such as lidar sensors for upwind wind-speed measurements) and actuators (outboard blade aerodynamic devices used in 'smart' blade technology). The use of individual blade pitch, although not considered an advanced actuator, was also described. The author concluded with some special control issues for offshore floating systems.

17 WIND ENERGY↗
DOE OSTI2023

Deep-Learning-Based Koopman Modeling for Online Control Synthesis of Nonlinear Power System Transient Dynamics

Power system stability and control have become more challenging due to the increasing uncertainty associated with renewable generation. Here, the performance of conventional control is highly driven by the physics-based offline-developed dynamic models that can deviate from the actual system characteristics under different operating conditions and/or configurations. Data-driven approaches based on online measurements can be a better solution to addressing these issues by capturing real-time operation conditions. This article describes a novel fully data-driven probabilistic framework to derive a linear representation of postcontingency grid dynamics and online prescribe control based on the derived model to enhance transient stability. The complex nonlinear power system dynamics is approximated by a linear model by using multiple neural network modules that infer distributions of the observations and introducing a Koopman layer to sample possible Koopman linear models from the inferred distributions. The trained model features linearity that can be easily incorporated into the existing linear control design paradigm and ease the controller design process. The effectiveness of Koopman-based control designs is validated through comparative case studies, which demonstrate increased prediction accuracy and control performance when applied to a power system with heterogeneous generator dynamics.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Methods for operating solar-thermochemical processes

Methods for controlling or operating solar thermochemical reactions process that maximize the two-step thermochemical energy cycle efficiency by a combination of pressure and temperature swing are disclosed.

Ermanoski, Ivan↗
DOE OSTI2017

Transparent group III metal nitride and method of manufacture

Large-area, low-cost single crystal transparent gallium-containing nitride crystals useful as substrates for fabricating GaN devices for electronic and/or optoelectronic applications are disclosed. The gallium-containing nitride crystals are formed by controlling impurity concentrations during ammonothermal growth and processing to control the relative concentrations of point defect species.

Jiang, Wenkan↗
DOE OSTI2020

Methods for operating solar-thermochemical processes

Methods for controlling or operating solar thermochemical reactions process that maximize the two-step thermochemical energy cycle efficiency by a combination of pressure and temperature swing are disclosed.

14 SOLAR ENERGY↗
DOE OSTI2023

Adaptive controller for forced oscillation suppression in the grid

A control system and method for an inverter-based resource device provided in a synchronous power grid. The control system includes at least one inverter based resource device connected to an electrical power system, and a controller module. The inverter based resource device includes a reference power Pref, a combination module and a transfer function. The inverter based resource device injects modulated power into the power system. The power system (which is represented by a transfer function in the control system) receives an undesirable forced oscillation, which is connected to a measuring device. A controller module processes the measured output and provides a control signal to the inverter based resource device. The controller is arranged to suppress a forced oscillation detected in the power system.

Guttromson, Ross↗
DOE OSTI2022

Reinforcement learning for online adaptation of model predictive controllers: Application to a selective catalytic reduction unit

Here we present a novel application of reinforcement learning (RL) for online dynamic tuning of model predictive controllers (MPC). Applying a state-action-reward-state-action (SARSA) algorithm for temporal difference learning with a control-specific reward function improves the error tracking performance of a standard MPC formulation. The proposed RL approach is also readily adaptable to other MPCs, or entirely different control approaches. Practical details for the implementation of the RL-MPC algorithm are also presented. The proposed algorithm is applied to a case study of controlling nitrogen oxide (NO x ) emissions in an industrial selective catalytic reduction (SCR) unit, a control problem characterized by significant nonlinearity and time delay. Along with an RL-MPC formulation for NOx control, another MPC is proposed to mitigate ammonia slip and decrease ammonia consumption in the SCR. Results showing the efficacy of the RL-MPC for NO x control through learning and implementation on the nonlinear SCR dynamic model are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Verification and Validation of Digitally Upgraded Control Rooms

As nuclear power plants undertake main control room modernization, a challenge is the lack of a clearly defined human factors process to follow. Verification and validation (V&V) as applied in the nuclear power community has tended to involve efforts such as integrated system validation, which comes at the tail end of the design stage. To fill in guidance gaps and create a step-by-step process for control room modernization, we have developed the Guideline for Operational Nuclear Usability and Knowledge Elicitation (GONUKE). This approach builds on best practices in the software industry, which prescribe an iterative user-centered approach featuring multiple cycles of design and evaluation. Nuclear regulatory guidance for control room design emphasizes summative evaluation—which occurs after the design is complete. In the GONUKE approach, evaluation is also performed at the formative stage of design—early in the design cycle using mockups and prototypes for evaluation. The evaluation may involve expert review (e.g., software heuristic evaluation at the formative stage and design verification against human factors standards like NUREG-0700 at the summative stage). The evaluation may also involve user testing (e.g., usability testing at the formative stage and integrated system validation at the summative stage). An additional, often overlooked component of evaluation is knowledge elicitation, which captures operator insights into the system. In this report we outline these evaluation types across design phases that support the overall modernization process. The objective is to provide industry-suitable guidance for steps to be taken in support of the design and evaluation of a new human-machine interface (HMI) in the control room. We suggest the value of early-stage V&V and highlight how this early-stage V&V can help improve the design process for control room modernization. We argue that there is a need to overcome two shortcomings of V&V in current practice—the propensity for late-stage V&V and the use of increasingly complex psychological assessment measures for V&V.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2026

Intelligent experiments through real-time AI: Fast Data Processing and Autonomous Detector Control for sPHENIX and future EIC detectors (Phase-I)

With an ever increasing demand for high precision data from modern detectors for discovery science and precision measurements, all major high energy nuclear and particle experiments, current and future, are facing the challenge on how to deal with the large volume of raw data generated from sophisticated state-of-the-art detectors in high rate collisions. These goals need to be balanced with available hardware and cost limits on DAQ (Data AcQuisition system) bandwidth and offline computing resources to capture, store and process the signal events. Two prototypical examples are the upcoming sPHENIX experiment, the DOE next generation heavy ion physics experiment at the Relativistic Heavy Ion Collider at BNL, and the future EIC experiments that are planned to be online circa 2030.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. In this paper, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally different from its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. Finally, these insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

The Path to Nitrate Salt Disposition

The topic is presented in a series of slides arranged according to the following outline: LANL nitrate salt incident as thermal runaway (thermally sensitive surrogates, full-scale tests), temperature control for processing, treatment options and down selection, assessment of engineering options, anticipated control set for treatment, and summary of the overall steps for RNS.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

MO-AB-BRA-02: Modeling Nanoparticle-Eluting Spacer Degradation During Brachytherapy Application with in Situ Dose-Painting

Purpose: Brachytherapy application with in situ dose-painting using gold nanoparticles (GNP) released from GNP-loaded brachytherapy spacers has been proposed as an innovative approach to increase therapeutic efficacy during brachytherapy. This work investigates the dosimetric impact of slow versus burst release of GNP from next generation biodegradable spacers. Methods: Mathematical models were developed based on experimental data to study the release of GNP from a spacer designed with FDA approved poly(lactic-co-glycolic acid) (PLGA) polymer. The diffusion controlled released process and PLGA polymer degradation kinetics was incorporated in the calculations for the first time. An in vivo determined diffusion coefficient was used for determining the concentration profiles and corresponding dose enhancement based on initial GNP-loading concentrations of 7 mg/g. Results: The results showed that there is significant delay before the concentration profile of GNP diffusion in the tumor is similar to that when burst release is assumed as in previous studies. For example, in the case of burst release after spacer administration, it took up to 25 days for all the GNP to be released from the spacer using diffusion controlled release process only. However, it took up to 45 days when a combined model for both diffusion and polymer degradation processes was used. Based on the tumor concentration profiles, a significant dose enhancement factor (DEF >20%), could be attained at a tumor distances of 5 mm from a spacer loaded with 10 nm GNP sizes. Conclusion: The results highlight the need to take the slow release of GNP from spacers and factors such as biodegradation of polymers into account in research development of GNP-eluting spacers for brachytherapy applications with in-situ dose-painting using gold nanoparticles. The findings suggest that I-125 may be the more appropriate for such applications given the relatively longer half-live compared to other radioisotopes like Pd-103 and Cs-131.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Advection, moistening, and shallow‐to‐deep convection transitions during the initiation and propagation of M adden‐ J ulian O scillation

Abstract Using observations from the 2011 AMIE/DYNAMO field campaign over the Indian Ocean and a high‐resolution regional model simulation, the processes that lead to the rapid shallow‐to‐deep convection transitions associated with the initiation and eastward propagation of the Madden‐Julian Oscillation (MJO) are examined. By tracking the evolution of the depth of several thousand individual model simulated precipitation features, the role of and the processes that control the observed midtropospheric moisture buildup ahead of the detection of deep convection are quantified at large and convection scales. The frequency of shallow‐to‐deep convection transitions is found to be sensitive to this midlevel moisture and large‐scale uplift. This uplift along with the decline of large‐scale drying by equator‐ward advection causes the moisture buildup leading to the initiation of the MJO. Convection scale moisture variability and uplift, and large‐scale zonal advection play secondary roles.

Hagos, Samson↗
DOE OSTI2017

Re-evaluation of Moisture Controls During ARIES Oxide Processing, Packaging and Characterization

DOE-STD-3013 [1] requires limiting the relative humidity (RH) in the glovebox during processing of the oxide product for specific types of plutonium oxides. This requirement is mandated in order to limit corrosion of the stainless steel containers by deliquescence of chloride salts if present in the PuO2. DOE-STD-3013 also specifies the need to limit and monitor internal pressure buildup in the 3013 containers due to the potential for the generation of free H2 and O2 gas from the radiolysis of surfaceadsorbed water. DOE-STD-3013 requires that the oxide sample taken for moisture content verification be representative of the stabilized material in the 3013 container. This is accomplished by either limiting the time between sampling and packaging, or by control of the glovebox relative humidity (%RH). This requirement ensures that the sample is not only representative, but also conservative from the standpoint of moisture content.

36 MATERIALS SCIENCE↗