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At least 469 records · Page 26

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NASA NTRSDate not supplied

Identifying Human Errors and Error Mechanisms From Accident Reports Using Large Language Models

Emerging operational concepts for aviation hinge on novel paradigms for human machine interaction. Critical to their safe operation is early consideration of human error into the design process. Existing methods for consideration of human error require significant expert input, which is challenging both in early design and in novel systems for which there is little existing safety expertise. In this research, we propose a methodology for identifying human error, error producing factors, and mechanisms in early design from historical incident reports. Additionally, we hypothesize that cross-domain sharing of lessons learned can aid with early design human considerations in circumstances where data is not relevant or incomplete. This is addressed by identifying causes of human error in aviation and railway domains through applying state-of-the art natural language processing techniques to historical incident reports. Using this method, it is possible to extract extensive reports on human error from past incidents. Using the proposed approach, we identify nine human errors from railway reports and fourteen from aviation reports, with three errors common to both domains. There is at least one error producing conditions for each human error while a majority of the errors have more than one error mechanism. We also found that a majority of the human errors, error producing factors, and error mechanisms (even if they are not common between the domains) can be used to inform safe operations across domains as long as the errors are not domain specific and are interpreted and contextualized using engineering judgement.

Human Errors↗

DOE OSTI2024

Tackling the Giants: Applying Smart Labs Principles to Constant Air Volume Lab Buildings

Laboratories typically consume 3 to 10 times more energy than similarly sized commercial buildings, and as much as 50% of that energy is wasted by inefficient and poorly operating fume hoods and ventilation systems. One challenge faced by older laboratory buildings is the heating, ventilation, and air-conditioning systems serving many of these buildings. The older systems are usually constant air volume (CAV) systems that maintain constant ventilation rates that cause excess airflow and inefficient energy use. Variable air volume systems can be more efficient systems with sensors to detect the need for a change in volumetric flow rate; however; renovation of ventilation systems can create disruption to ongoing research and operations along with considerable up-front costs. When a Smart Labs program is implemented, an organization has a systems-based management approach that yields a high-performing laboratory building. As decarbonization continues as a priority for sites, buildings with CAV systems are difficult to address. This work centers around practical guidance for improving lab buildings with CAV. In conjunction with industry input on top technology solutions and best practices, recommendations will include performing a laboratory ventilation risk assessment in conjunction with robust retro-commissioning work, which is a crucial step in the Smart Lab process. By applying Smart Labs principles, the aging laboratory building stock of 153,343 (Lawrence Berkeley National Laboratory [LBNL] 2017), comprising roughly 500,000 lab spaces in the United States, can be brought to safe and high-performance operations.

building↗

NASA NTRSDate not supplied

Assessment of a Surface Propellant Transportation System Concept for Operations on Mars

NASA is working to define the architecture needed for a Mars exploration campaign. One potential architecture option allows for pre-deployment of essential cargo and equipment to support a crew landing, including the pre-positioning of a Mars Ascent Vehicle (MAV). This MAV is likely to represent the largest single payload that must be landed on the Martian surface. Its size would be influenced by the amount of mass that state-of-the-art Entry, Descent, and Landing (EDL) systems would be capable of placing on Mars. One possible method of increasing the usable size of the MAV without exceeding available EDL capabilities is to land the MAV without its ascent propellant on board. Following such a method may necessitate a strategy to acquire sufficient ascent propellant to allow a crew to safely depart the Martian surface. This paper describes a conceptual return propellant strategy that uses a liquid transportation skid, or pallet, to be used in conjunction with a rover mobility system to transfer cryogenic propellant, consisting of oxygen and methane, across the Martian surface from a delivery lander to the MAV to enable its launch. Design considerations, concept of operations, and rover energetics will be discussed in this paper.

Propellant↗

NASA NTRSDate not supplied

Assessment of a Surface Propellant Transportation System Concept for Operations on Mars

NASA is working to define the architecture needed for a Mars exploration campaign. One potential architecture option allows for pre-deployment of essential cargo and equipment to support a crew landing, including the pre-positioning of a Mars Ascent Vehicle (MAV). This MAV is likely to represent the largest single payload that must be landed on the Martian surface. Its size would be influenced by the amount of mass that state-of-the-art Entry, Descent, and Landing (EDL) systems would be capable of placing on Mars. One possible method of increasing the usable size of the MAV without exceeding available EDL capabilities is to land the MAV without its ascent propellant on board. Following such a method may necessitate a strategy to acquire sufficient ascent propellant to allow a crew to safely depart the Martian surface. This presentation describes a conceptual return propellant strategy that uses a liquid transportation skid, or pallet, to be used in conjunction with a rover mobility system to transfer cryogenic propellant, consisting of oxygen and methane, across the Martian surface from a delivery lander to the MAV to enable its launch. Design considerations, concept of operations, and rover energetics will be discussed in this presentation.

Surface↗

NASA NTRS2025

A Summary of Results from Vertical Drop Testing of Hybrid III and WIAMan ATDs

With the development and maturation of the Urban Air Mobility (UAM) market, many new types of electric vertical take-off and landing (eVTOL) vehicles will be flying in the national airspace carrying goods, people or conducting operations for a variety of missions. These types of vehicles are unlike current aircraft due to their novel design and operational profile. Several considerations must be examined in areas including noise, comfort and safety in order for these vehicles to be utilized and accepted into the current airspace system. Researchers at NASA Langley Research Center (LaRC) have conducted sub-scale and full-scale tests on representative eVTOL airframes and seats under a variety of dynamic impact conditions. These tests were conducted to generate data necessary to inform the development of standards in the areas specific to crashworthiness of eVTOL vehicle systems and safety. The data in this report relates to occupant responses obtained during a test campaign utilizing various makes, models, and sizes of Anthropomorphic Test Devices (ATD’s, a.k.a. crash test dummies) undergoing vertical impacts in a variety of seats. The data is intended to provide occupant behavior response and injury metrics for several anticipated impact scenarios that may occur in eVTOL operations. This report will present test data highlighting the effects of several variables on the test results. Discussions on the ATD sizes, along with comparisons between different ATD makes and types will be included. The performance of an in-house developed energy absorbing seat will be detailed, and discussions pertaining to the applicability in various loading conditions will be presented. Finally, a discussion as to the applicability of the tested results to eVTOL full-scale conditions will be included.

Dynamic Drop Testing↗

NASA NTRS2024

Development of a Surface Water Transportation System for ISRU Operations on Mars

NASA is working to define the architecture needed for a Mars exploration campaign. Initial analysis assumptions allow for pre-deployment of essential cargo and equipment to support a crew landing, including the pre-positioning of a Mars Ascent Vehicle (MAV). This MAV is likely to represent the largest single payload that must be landed on the Mars surface. Its size would be influenced by the amount of mass that state-of-the-art Entry, Descent, and Landing (EDL) systems would be capable of placing on Mars. One possible method of increasing the usable size of the MAV without exceeding available EDL capabilities is to land the MAV without ascent propellant on board. Following such a method may necessitate a strategy to acquire sufficient ascent propellant to allow a crew to safely depart the Martian surface. This paper describes a conceptual return propellant strategy that uses a liquid transportation skid, or pallet, to be used in conjunction with a rover mobility system to transfer water across the Martian surface from a source point to an in-situ resource utilization (ISRU) plant that would use this water as a feedstock to generate oxygen and methane to enable launch of the MAV. Design considerations, concept of operations, and rover energetics will be discussed in this paper.

Fluid Structure Interface↗

NASA NTRSDate not supplied

Assessment of a Surface Water Transportation System for ISRU Operations on Mars

Fluid Structure Interface↗

NASA NTRS1939

Engine Operation in Flight for Minimum Fuel Consumption

Engine and airplane performance data have been gathered from various sources and analyzed to determine indications of the most economical methods of flight operation from a consideration of fuel expenditure. The analysis includes the influence of such facts as fuel-air ratio, engine speed, engine knock, altitude, cylinder cooling, spark timing, and limits of cruising brake mean effective pressure. The results indicate that the cheapest power is obtained with approximately correct mixture at low engine speed and highest permissible manifold pressure. If more power is desired, the methods of obtaining it are, in order of fuel economy: (a) increasing the engine speed and maintaining safe cylinder temperatures by cooling; (b) retarding the spark or cooling further to permit higher manifold pressure; and, (c) riching the mixture. The analysis further shows that the maximum time endurance of flight occurs at the air speed corresponding to minimum thrust horsepower required and with minimum practicable engine speed. Maximum mileage per pound of fuel is obtained at slightly higher air speed. The fuel-air ratio should be approximately the theoretically correct ratio in both cases. For an engine equipped with a geared supercharger, as in the example presented, and with knock as the limiting condition, a comparison of operation at sea level and at 6,000 feet shoes flight at altitude to be more economical on the basis of both range and endurance.

Reuter, George↗

NASA NTRS2011

Assessment of Durable SiC JFET Technology for +600 C to -125 C Integrated Circuit Operation

Electrical characteristics and circuit design considerations for prototype 6H-SiC JFET integrated circuits (ICs) operating over the broad temperature range of -125 C to +600 C are described. Strategic implementation of circuits with transistors and resistors in the same 6H-SiC n-channel layer enabled ICs with nearly temperature-independent functionality to be achieved. The frequency performance of the circuits declined at temperatures increasingly below or above room temperature, roughly corresponding to the change in 6H-SiC n-channel resistance arising from incomplete carrier ionization at low temperature and decreased electron mobility at high temperature. In addition to very broad temperature functionality, these simple digital and analog demonstration integrated circuits successfully operated with little change in functional characteristics over the course of thousands of hours at 500 C before experiencing interconnect-related failures. With appropriate further development, these initial results establish a new technology foundation for realizing durable 500 C ICs for combustion engine sensing and control, deep-well drilling, and other harsh-environment applications.

Neudeck, P. G.↗

DOE OSTI2025

Time-resolved electrical potential pump – X-ray photoelectron spectroscopy probe developments for investigating dynamic processes occurring at electrochemical interfaces

Electrode–electrolyte interfaces are of critical importance in several fields, including renewable energy, corrosion, and environmental chemistry. However, investigating these interfaces under operational conditions poses considerable challenges due to the limitations of the instrumentation employed. While recent advancements in in situ and operando techniques have enhanced our comprehension of the steady-state properties of solid-liquid interfaces, the dynamic behaviors of these systems remain inadequately explored. This study introduces a time-resolved X-ray photoelectron spectroscopy (XPS) technique designed to capture transient reaction intermediates and charging dynamics at electrified interfaces. The presented proof-of-principle study demonstrates that electrochemical processes, represented by an equivalent electrical circuit (EEC) model, can be probed and understood using square wave voltage pulses of a potentiostat synchronized to the modified data acquisition of an XPS setup. This method offers a valuable alternative to traditional pump–probe techniques, facilitating the investigation of a broader range of electrochemical systems. A dedicated software package for analyzing time- and energy-resolved XPS with a focus on extracting parameters of the EEC is geared towards benchmarking different EECs in future real-world electrochemical experiments.

Electrochemistry↗

DOE OSTI2023

Advances and prospects to achieve high-performing and durable proton-exchange-membrane unitized regenerative fuel cells

Proton-exchange-membrane unitized regenerative fuel cell (PEM-URFC) is a promising energy storage and conversion device for large-scale and long-term applications. Previous research has primarily focused on materials development studies, with performance and durability not evaluated at relevant conditions. Such an approach becomes insufficient for making URFC technology commercially competitive. In this review, we highlight recent progress on high-performing PEM-URFCs, focusing on electrode engineering, key components, and operating approaches that take realistic operating conditions into consideration. Key components of a membrane electrode assembly (MEA), including catalyst layer, diffusion media, and membrane, which require different optimization strategies, are discussed in this review.

25 ENERGY STORAGE↗

DOE OSTI2024

Iodine solid sorbent design: a literature review of the critical criteria for consideration

Designing sorbents for iodine capture in different conditions requires selection and optimization of a large and diverse range of variables. These variables fall into general categories (or features) of sorbent activity, sorbent stability, and the fate of the loaded material in terms of the disposal (waste form) options available. To illustrate, silver-loaded, high-porosity sorbents make for maximized iodine capture and less pressure drop in a column-based sorption system approach, however, this high porosity can lead to less mechanically stable sorbents. Additionally, waste forms containing silver must also be compliant with additional criteria for hazardous waste disposal. Thus, all these aspects must be considered simultaneously when selecting a sorbent for utilization under specific conditions. Information is given for different types of sorbent design considerations for different operating conditions and some emphasis is also given on promising alternatives for silver as the active (chemisorption-based) getter metal. Discussion is given around demonstrated options for waste forms for different metal-iodide compounds.

36 MATERIALS SCIENCE↗

DOE OSTI2022

AR reactor neutronics multi-code validation*

The affordable, robust, compact (ARC) reactor is a tokamak fusion reactor concept currently under development by Commonwealth Fusion Systems and Massachusetts Institute of Technology. There are three important neutronics considerations for the operation of the ARC reactor: (1) breeding of enough tritium in the blanket to sustain the D–T reaction in the plasma; (2) ensuring low fluence on the superconducting toroidal field coils; and (3) assessing neutron volumetric heating in structural components. Here, this work aims to perform a validation of the neutronics analysis approach by code-to-code comparison. State-of-the-art software stacks are employed for the neutronics analysis of the ARC reactor, and a computer-aided design (CAD) model is used directly for Monte Carlo (MC) neutron transport calculations. Three software stacks, Attila-MCNP, OpenMC-DAGMC, and Shift-DAGMC, are used to perform neutronic analyses of a 90° sector CAD model of the ARC reactor. In conclusion, results show that the flux tallies calculated by the three software stacks are very close. Also, the volumetric heating and tritium breeding values have less than 0.6% relative difference between codes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2021

Modeling and Analysis of DC Microgrids as Stochastic Hybrid Systems

This study proposes a method of predicting the influence of random load behavior on the dynamics of dc microgrids and distribution systems. This is accomplished by combining stochastic load models and deterministic microgrid models. Together, these elements constitute a stochastic hybrid system. The resulting model enables straightforward calculation of dynamic state moments, which are used to assess the probability of desirable operating conditions. Specific consideration is given to systems based on the dual active bridge (DAB) topology. Bounds are derived for the probability of zero voltage switching (ZVS) in DAB converters. A simple example is presented to demonstrate how these bounds may be used to improve ZVS performance as an optimization problem. In conclusion, predictions of state moment dynamics and ZVS probability assessments are verified through comparisons to Monte Carlo simulations.

42 ENGINEERING↗

DOE OSTI2024

Coarse Mesh Finite Difference Acceleration for Pebble Tracking Transport in Griffin

We implemented a coarse mesh finite difference (CMFD) for accelerating transport calculations with PTT (pebble tracking transport) in the Griffin code. More specifically, extensions for transport update with the consideration of scattering operator and CMFD projection were implemented for PTT. The implementation was verified with a simplified PBR (pebble bed reactor) benchmark problem and significant performance improvements in CPU time was observed.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2026

Airport Ground Support Equipment Analysis

Ground support equipment (GSE) plays a critical role in providing services to aircraft at arrival and departure gates, ensuring smooth and efficient airport operations. As the airline industry seeks to reduce costs and expand energy options, electric GSE (eGSE) is emerging as a promising solution. This project examines the integration of eGSE into airport operations, addressing key considerations such as vehicle deployment, charging infrastructure, and grid impacts. We developed a flexible, bottom-up modeling framework to evaluate energy demands and infrastructure requirements across more than 300 U.S. airports, providing actionable insights to support electrification planning and implementation. The study focuses on eight major types of GSE with commercially available electric counterparts: aircraft tractors, ground power units, baggage tractors, belt loaders, cargo loaders, catering trucks, lavatory trucks, and water trucks. Project results include annual charging load profiles, total energy consumption, and the charger and fleet requirements for each airport.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2021

Evaluation of a Surface Spill Operation to Return Adult Steelhead Overshoots Downstream of McNary Dam

This study, funded by the U.S. Army Corps of Engineers (USACE), was conducted by the Pacific Northwest National Laboratory to evaluate the efficacy of operating one Top Spill Weir (TSW) at McNary Dam outside the normal TSW operation dates for juvenile salmon passage. Of interest is whether the TSW is an effective downstream passage route for adult steelhead overshoots. Overshoots are fish which, having passed upstream at McNary Dam, must pass downstream to return to their natal stream to spawn. This report covers Fall (2019) and Spring (2020) study periods. The study design arranged the available 24 hours of TSW spill per week into weekly blocks with sub-blocks differentiated into day and night operations with TSW discharge periods of 4- and 8-hours duration. Hydroacoustic techniques were used to sample adult fish passage at the TSW and at turbine units 1 and 10. The experimental design contrasted TSW spill periods of differing duration and at different times of the day. The small number of fish detected passing the TSW, and the smaller number of fish detected passing the turbine units, were best suited to an ad hoc, exploratory approach to evaluating the effect of TSW spill. It is worthwhile to note that the operations data obtained for the fall study period had a greater than expected number of gaps and apparent anomalies that we believe were a result of how the data were aggregated. These problems are not particularly problematic for the present study, because the available data still provide a good indication of whether the TSW was operating at each point in time. TSW flows in both fall and spring data sets were able to be cleaned up using the established relationship between forebay elevation and TSW discharge rate. Additional cleanup of operations data would be needed, however, if more quantitative evaluation of dam-wide flow and passage relationships were needed. This study contrasted TSW spill periods of differing duration and at different times of the day. The small number of fish detected passing the TSW, and the smaller number of fish detected passing the turbine units were best suited to an ad hoc, exploratory approach to evaluating the effect of TSW spill. Spring adult steelhead passage numbers estimated using hydroacoustics were notably lower than during the fall study period, and that was consistent with our analysis of PIT tagged fish likely to be in the vicinity during each study period. Detections of fish in BlueView sampling areas upstream of the TSW and powerhouse were not correlated with detections of fish passing hydroacoustic sampling areas, which suggests that fish approaching the face of the dam can move around the forebay before passing. Other fish detected in the forebay in large numbers, such as shad, were able to be filtered out of steelhead passage counts and did not appear to be influencing hydroacoustic passage rate estimates. A pulse of passage at the initial TSW opening was weakly evident, but trends across 4- and 8-hour operational periods did not show a distinct decline in passage over time as TSW operation continued. Our findings do not indicate a reason to choose one 8-hour period over two 4-hour periods, or vice versa. This suggests that the duration of spill periods can be chosen based on operational or other considerations. Passage rates were consistently higher during the daytime TSW discharge periods, relative to nighttime TSW discharge periods. The experimental design of the current study used start times near dawn for day periods and near dusk for night periods.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2020

Degradation and Failure Phenomena of Accident Tolerant Fuel Concepts: FeCrAl Alloy Cladding

The U.S. Nuclear Regulatory Commission (NRC) is anticipating licensing applications and commercial use of accident tolerant fuel (ATF) in United States commercial nuclear power reactors. Pacific Northwest National Laboratory is providing technical assistance to the NRC related to the newly proposed nuclear fuel and cladding designs. This report focuses specifically on the iron-chromium-aluminum (FeCrAl) alloys being investigated to replace zirconium-based alloys for fuel cladding and provides current state-of-the-industry information on material properties and fuel performance considerations under reactor operating conditions and design basis accident conditions. Currently, Global Nuclear Fuels (GNF) is the only U.S.-based fuel vendor considering FeCrAl cladding as a near-term ATF design. GNF has tested several different FeCrAl alloys including Kanthal APMT, C26M, and MA956; fueled C26M rods and unfueled Kanthal APMT, C26M, and MA956 rods have been inserted in lead test assemblies at Plants Hatch and Clinton. This report will focus on those three alloys specifically, with broader information given regarding in-reactor and ex-reactor testing of FeCrAl alloys. To support the NRC’s readiness efforts, this report will identify and discuss degradation and failure modes of FeCrAl cladding concepts, including fuel performance characteristics that may not be addressed within existing regulatory documents.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗