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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

High Performance Platinum Group Metal Free Membrane Electrode Assemblies through Control of Interfacial Processes

The quantitative goal of this project was to produce a high-performance anion exchange membrane water electrolyzer (AEM-WE) completely free of platinum group metals (PGMs), which could operate for at least 500 hours with less than 50 microV/hour degradation, at 500 mA/cm 2 . To achieve this goal, work focused on the optimization of electrocatalyst conductivity, with dispersion and utilization in the membrane electrode assembly (MEA) improved through refinement of deposition techniques. Critical factors were also explored with significant work undertaken by Northeastern University to further understand catalyst-membrane-ionomer interfaces and how they differ from liquid electrolyte. Water management and optimal cell operational parameters were established through the design, fabrication, and test of a new test station at Proton specific for AEM evaluation. Additionally, AEM material stability and robustness at high potentials and gas evolution conditions were advanced at Penn State.

08 HYDROGEN↗
DOE OSTI2011

US Veteran Gets a Facelift

Idaho National Laboratory's Advanced Test Reactor (ATR) has received replacement instrumentation and control systems - the process distributed control system (DCS) and the console display system (CDS), which included a replacement annunciator subsystem. The new systems offer the latest software and technology advancements, ensuring the availability of the reactor for future energy research. ATR, a pressurized, light water moderated 250 MW materials test reactor, became operational in 1965. In the early 1990s, after nearly thirty years of analogue/pneumatic controls, the laboratory upgraded ATR to digital-based instrumentation and control systems. By 2007, the equipment and technology used in these digital systems were reaching the end of their lifecycle. The systems component failure rates were on a rise, while vendor support and parts availability were declining. With current projections and plans for operating ATR into 2040, modernization of the reactor's infrastructure is necessary to maintain reliability and efficiency. As a result, the Idaho National Laboratory and the U.S. Department of Energy (DOE) invested more than $13 million in a four-year project to replace ATR's instrumentation and control systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2012

Linearization Techniques for Controlled Piecewise Deterministic Markov Processes; Application to Zubov's Method

We aim at characterizing domains of attraction for controlled piecewise deterministic processes using an occupational measure formulation and Zubov's approach. Firstly, we provide linear programming (primal and dual) formulations of discounted, infinite horizon control problems for PDMPs. These formulations involve an infinite-dimensional set of probability measures and are obtained using viscosity solutions theory. Secondly, these tools allow to construct stabilizing measures and to avoid the assumption of stability under concatenation for controls. The domain of controllability is then characterized as some level set of a convenient solution of the associated Hamilton-Jacobi integral-differential equation. The theoretical results are applied to PDMPs associated to stochastic gene networks. Explicit computations are given for Cook's model for gene expression.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Statistical analysis of the Nb 3 Sn strand production for the ITER toroidal field coils

The ITER toroidal field (TF) strand procurement initiated the largest Nb 3 Sn superconducting strand production hitherto. The industrial-scale production started in Japan in 2008 and finished in summer 2015. Six ITER partners (so-called Domestic Agencies, or DAs) are in charge of the procurement and involved eight different strand suppliers all over the world, of which four are using the bronze route (BR) process and four the internal-tin (IT) process. In total more than 500 tons have been produced including excess material covering losses during the conductor manufacturing process, in particular the cabling. The procurement is based on a functional specification where the main strand requirements like critical current, hysteresis losses, Cu ratio and residual resistance ratio are specified but not the strand production process or layout. We introduce the analysis on the data acquired during the quality control (QC) process that was carried out to ensure the same conductor performance requirements are met by the different strand suppliers regardless of strand design. The strand QC is based on 100% billet testing and on applying statistical process control (SPC) limits. Throughout the production, samples adjacent to the strand pieces tested by the suppliers are cross-checked ('verified') by their respective DAs reference labs. The level of verification was lowered from 100% at the beginning of the procurement progressively to approximately 25% during the final phase of production. Based on the complete dataset of the TF strand production, an analysis of the SPC limits of the critical strand parameters is made and the related process capability indices are calculated. In view of the large-scale production and costs, key manufacturing parameters such as billet yield, number of breakages and piece-length distribution are also discussed. Furthermore, the results are compared among all the strand suppliers, focusing on the difference between BR and IT processes. Following the completion of the largest Nb 3 Sn strand production, our experience gained from monitoring the execution of the QC activities and from auditing the results from the measurements is summarised for future superconducting strand material procurement activities.

Vostner, A.↗
DOE OSTI2016

Impulsive Control for Continuous-Time Markov Decision Processes: A Linear Programming Approach

In this paper, we investigate an optimization problem for continuous-time Markov decision processes with both impulsive and continuous controls. We consider the so-called constrained problem where the objective of the controller is to minimize a total expected discounted optimality criterion associated with a cost rate function while keeping other performance criteria of the same form, but associated with different cost rate functions, below some given bounds. Our model allows multiple impulses at the same time moment. The main objective of this work is to study the associated linear program defined on a space of measures including the occupation measures of the controlled process and to provide sufficient conditions to ensure the existence of an optimal control.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Dynamic Beam Shape Sensing and Control in an Open Architecture Metal AM System for Microstructure Manipulation

Most commercially available metal additive manufacturing (AM) systems are closed-architecture, meaning that the system manufacturer limits the ability of the user to directly control the process conditions and can modify the specified inputs using proprietary methods. Unfortunately, this approach severely limits or confounds the ability for users to perform research on fundamental aspects of additive manufacturing. ARCTOS Technology Solutions (ARCTOS) produces an open-architecture laser powder bed fusion (PBF) additive manufacturing system that allows the user to fully control all aspects of the process control and monitoring. The purpose of this project is to help develop beam shaping capabilities and controls within the ARCTOS open-architecture system for control of microstructure evolution during metal AM.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Machine learning informed control systems for extrusion printing processes

Systems and methods for controlling a material extrusion device to extrude a filament of an ink are provided. An extrusion printing control system collects from one or more sensors measurements representing an internal state of material extrusion processing during extrusion of the filament. In addition, the system collects an image of the filament as the filament is extruded. The system applies a classifier to the collected image to generate an image-derived state characterizing the filament. Based on the internal state and the image-derived state, the system estimates a derived state using a model. The system determines control parameters using the model to achieve a desired quality of the filament by minimizing a cost function based on the internal state, the image-derived state, the derived state, and constraints of the material extrusion device. Finally, the system provides the control parameters to a controller of the material extrusion device.

Howell, Brian↗
DOE OSTI2017

Control of the clustering process in molecular beams using IR lasers

The control of clustering in molecular beams with the help of IR lasers is experimentally studied. Studies were performed with a molecular CF{sub 3}I gas diluted with argon or xenon using a cw CO{sub 2} laser. The control of clustering is based on the resonance vibrational excitation of molecules or clusters by the IR laser radiation near the nozzle exit. Depending on the distance from the excitation region to the nozzle cut, the irradiation of the molecular beam either suppresses the clustering of resonantly excited molecules (when the beam is irradiated near the nozzle exit where clustering occurs) or causes the dissociation of small clusters (when the beam is irradiated away from the nozzle where clustering is at the growth stage). The suppression of molecular clustering and the dissociation of clusters in beams were studied by measuring and analyzing the integrated intensities of ion peaks of cluster fragments with a time-of-flight spectrometer. The efficiencies of clustering suppression and cluster dissociation were studied as functions of exciting laser radiation parameters, the beam irradiation geometry, gas parameters over the nozzle, and the nozzle construction. It is shown that the efficiencies of clustering suppression and cluster dissociation strongly depend on the exciting laser radiation intensity, the nozzle construction, and the distance from the irradiation region to the nozzle cut. Parameters providing the most efficient control of clustering suppression and cluster dissociation are found.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Apparatus to control the total energy flux into the top ingot surface during vacuum arc remelting processes

A Vacuum Arc Remelting controller apparatus wherein process control is accomplished primarily through control of pool power. Pool power being defined as the total energy flux into a top ingot surface of the VAR ingot. The controller apparatus of the present invention comprises a controller computer that transmits commands to the host furnace through an ethernet connection.

42 ENGINEERING↗
DOE OSTI2025

Employing a Hardware-in-the-Loop Approach to Realize a Fully Homomorphic Controller for a Small Modular Advanced High Temperature Reactor

This paper addresses the cybersecurity challenges of advanced nuclear reactors by integrating fully homomorphic encryption (FHE) into their control systems, enabling encrypted processing of control signals without compromising functionality. Advanced nuclear reactors, including Small Modular Reactors (SMRs) and microreactors, aim to achieve autonomous and remote operations, reducing costs and enhancing competitiveness. However, these advancements expand the attack surface for cyberattacks, particularly in autonomous and remote operation scenarios. Cyberattacks can exploit vulnerabilities to manipulate physical processes, causing shutdowns, asset damage, or public harm. Such attacks begin with passive reconnaissance, where adversaries intercept communications or observe behaviors to gather information, which is then leveraged to execute cyber-physical attacks by injecting malicious commands. Nuclear power must adopt cybersecurity protection measures to secure the integrity and availability of their digital control systems. This paper demonstrates the application of FHE to secure operations by enabling encrypted processing of sensitive signals and parameters -- ensuring privacy without exposing data. FHE supports secure mathematical operations on encrypted data without requiring decryption. Using a hardware-in-the-loop (HIL) approach, this paper implements an FHE-integrated controller on a BeagleBone Black (BBB) controlling a simulation of the Small Modular Advanced High Temperature Reactor (SmAHTR). By doing so, the encrypted controller protects the integrity of critical set points and control signals during transmission and processing. Thus, FHE-integrated controllers enhance secure operations of advanced nuclear reactors while maintaining functionality.

control systems↗