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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

A Deep Learning Approach for In-Network Synchrophasor Missing Data Recovery Using Programmable Network Switches

Phasor measurement unit (PMU) networks deliver accurate and timely measurements, which is essential for managing today’s electric power systems. To ensure data quality and enhance the cyber-resilience of PMU networks against malicious attacks and data errors, this study presents an online PMU missing data recovery scheme by leveraging P4 programmable switches. The data plane incorporates a customized PMU protocol parser that abstracts the necessary payload data for recovery. Recovery processes are executed in the control plane using a pre-trained machine learning model. Both traditional and advanced ML models, such as transformer and TimeGPT, are explicitly employed for data prediction. This approach ensures rapid and precise data recovery. Performance evaluations focus on recovery speed and accuracy, using a real dataset from a campus microgrid. With 20% missing PMU data, the mean absolute percentage error for voltage magnitude is 0.0384%, and the phase angle error discrepancy is approximately 0.4064%.

Phasor Measurement Unit, Machine Learning, Program↗
DOE OSTI2021

Results of the 2018 Wood Stove Design Challenge

The 2018 Wood Stove Design Challenge was an international design competition which sought to identify top performing residential wood stoves based on automation. To prepare for the event, the Northeast States for Coordinated Air Use Management (NESCAUM) developed a testing protocol that challenged the stoves by testing them in more field-like conditions—capturing emissions from start-up, reloading a stove, and the use of larger piece sizes. Flue gas emissions were measured using a combination of in-stack and novel dilution sampling methods, as the event occurred on the National Mall in Washington D.C. in a non-laboratory setting. Particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were measured from three stoves in real-time. A combustion efficiency was also calculated for each stove in real-time. Measured PM emission rates ranged between 1.8 and 8.0 g/hr for all stoves and operating conditions, with the highest emissions being measured during cold start in all cases. The test average PM emission rates were 2.4, 4.0, and 2.4 g/hr for stoves A, B, and C, respectively. Results showed emissions measured during transient operations, which are often excluded in current certification methods, can be significantly higher than steady-state periods—echoing other studies and highlighting the importance of testing in various operational modes for more realistic emission estimates. Additionally, the stoves had overall CO emission rates of 48.8, 284.8, and 100.8 g/hr, for stoves A, B and C, respectively. Calculated PM and CO emission factors overall were low considering the testing protocol sought to follow more challenging yet realistic practices in terms of fuel loading and operating procedures. The overall estimated combustion efficiency for stoves A, B, and C was 85%, 78%, 76%, respectively and in all cases was lowest during the cold start period.This report details the successfully proposed and assembled instrumentation that was relatively portable for field-site testing and the results of the emissions measurements for the 2018 Wood Stove Design Challenge competition. Overall, the repeatability of each stove was favorable with coefficients of variation (COV) ranging from 7 to 15% for measured PM concentrations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

Megahertz Rate Optical Diagnostics of Explosively Generated Soot

Detonation of a solid explosive produces a turbulent and luminous post‐detonation fireball containing condensed carbon soot. Diagnostics of soot dynamics are needed for model validation and to interpret emission signals. Diffuse back‐illumination extinction imaging (DBI‐EI) and laser‐induced incandescence (LII) are two common optical diagnostics for flame soot. This work extends both to measure time‐resolved soot dynamics from a 12 mm HMX hemisphere. DBI‐EI measured line‐of‐sight optical extinction exceeds 99% in some regions. Results are tomographically inverted to obtain a signal proportional to the soot volume fraction. Pulse‐burst LII measures are presented at 1 MHz. For the first time, LII results are combined with DBI‐EI extinction measurements to quantify and correct for signal trapping. Following this, spatially and temporally resolved DBI‐EI and LII measures are shown to be in reasonable agreement. Finally, experimental results are compared against recently developed simulations. Quantitative differences in the soot mixing dynamics are resolved. These findings motivate future model improvements and demonstrate ongoing needs for diagnostic advancements for heavily sooting environments.

diffuse back-illumination extinction imaging↗
DOE OSTI2023

Spectro-Microscopy Studies of Atmospheric Particles

Our project investigated composition and physical properties of individual atmospheric particles collected in field campaigns organized by the DOE Atmospheric Systems Research and Atmospheric Radiation Measurement (ASR/ARM) programs, such as the Green Ocean Amazon (GoAmazon, 2014/5), the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE, 2016/7), the Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA, 2017/8), the Aerosol–Ice Formation Closure Pilot Study (AEROICESTUDY, 2019) and in additional small-scale supporting field experiments focused on the investigation of the light-absorbing (aka brown carbon) atmospheric particles. In these studies, we investigated the contribution of natural and anthropogenic sources to populations of atmospheric particles during representative atmospheric conditions; characterized particle composition and evaluated their hygroscopic properties and propensity to act as cloud condensation nuclei (CCN) and ice nuclei (IN); correlated typical particle-type and mixing state characteristics with real-time measurements in the areas of studies. We used multi-modal spectro-microscopy techniques to examine elemental and molecular composition, mixing state, size, and higher order morphology for individual particles. Specifically, we used computer-controlled scanning electron microscopy and X-ray microanalysis for quantitative analysis of particle elemental composition, and we used transmission electron microscopy to provide additional information on the distribution of different components within individual particles (particle heterogeneity). We used synchrotron-based scanning transmission X-ray microscopy for quantitative description of the mixing state and molecular bonding of carbon in particles. The particle composition, mixing state, and morphology from analyzed periods was then combined with the real-time ARM measurements of aerosol size distribution, CCN concentration, hygroscopicity, and aerosol bulk composition. Combined together, results of our studies allowed us to assess the major particle sources (biogenic vs. anthropogenic, primary vs secondary) and gain insight into the atmospheric processing of aerosol particles resulting from condensation, coagulation, oxidative aging, and cloud processing. In collaboration with other scientists involved in field campaigns, we carried out statistical analysis of particle properties and their source-specific contributions to regional aerosol loading under representative air mass, meteorological, and cloud conditions.

scanning transmission X-ray microscopy↗
DOE OSTI2022

Standardizing reverberation-measured C iv time-lag quasars, and using them with standardized Mg ii quasars to constrain cosmological parameters

ABSTRACT We use 38 C iv quasar (QSO) reverberation-mapped observations, which span eight orders of magnitude in luminosity and the redshift range 0.001064 ≤ z ≤ 3.368, to simultaneously constrain cosmological-model and QSO radius–luminosity (R–L) relation parameters in six cosmological models, using an improved technique that more correctly accounts for the asymmetric errors bars of the time-lag measurements. We find that R–L relation parameters are independent of the cosmological models used in the analysis and so the R–L relation can be used to standardize the C iv QSOs. The C iv QSO cosmological constraints are consistent with those from Mg ii QSOs, allowing us to derive joint C iv + Mg ii QSO cosmological constraints which are consistent with currently accelerated cosmological expansion, as well as consistent with cosmological constraints derived using better-established baryon acoustic oscillation (BAO) and Hubble parameter [H(z)] measurements. When jointly analysed with H(z) + BAO data, current C iv + Mg ii QSO data mildly tighten current H(z) + BAO data cosmological constraints.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

A new generation of uranium coincidence fast neutron collars for assay of LWR fresh fuel assemblies

The active uranium neutron coincidence collar provides a means of non-destructively assaying the fissile linear density of Light Water Reactor fresh fuel assemblies containing low enriched uranium. These neutron collars can operate in two modes: a thermal and a fast mode. In fast mode, a neutron collar has an added cadmium (Cd) liner in the sample cavity of the detector to reduce the impact of the burnable poison (thermal neutron absorber) on the detector signal (doubles). The main advantage for operating in fast mode is a detected signal that is less dependent of the burnable neutron poison content and thus less dependent on facility operator declarations. The drawback is that operating in fast mode requires a longer measurement time (~hour vs tens of minutes for thermal mode) to achieve the statistically needed precision in the measurements. The trend in the modern reactor fuel assemblies is moving to higher burnup by using higher initial enrichment and, consequently, a higher number of burnable poison rods to compensate the initial neutron reactivity. The increase of the burnable poison loading has motivated the development of a new generation of high efficiency fast neutron collars to allow practical measurements in-field by nuclear inspectors. This paper describes the development and performance evaluation of a new generation of neutron collars, for both boiling water reactor (BWR) and pressurized water reactor (PWR) fuels, jointly developed between the US Department of Energy, through Los Alamos National Laboratory, and the Euratom Safeguards Directorate of the European Commission. In this work, we present here calibrations with reference fuel assemblies at Los Alamos National Laboratory as well as the results of in-field measurement campaigns in fuel fabrication plants with modern commercial fuel assemblies. The experimental results show that a typical PWR verification can be made in a total time of 30 min with an uncertainty in the measured mass of 2% at one standard deviation (1σ). A BWR verification can be made in 47 min with an uncertainty in the measured mass of 1.9% at 1σ, or a total time of 20 min with 1σ uncertainty in the measured mass of 2.5%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Ultrafast Dynamics of Excited Electronic States in Nitrobenzene Measured by Ultrafast Transient Polarization Spectroscopy

We investigate ultrafast dynamics of the lowest singlet excited electronic state in liquid nitrobenzene using ultrafast transient polarization spectroscopy, extending the well-known technique of optical Kerr effect spectroscopy to excited electronic states. The third-order nonlinear response of the excited molecular ensemble is measured using a pair of femtosecond pulses following a third femtosecond pulse that populates the S 1 excited state. By measuring this response, which is highly sensitive to details of the excited state character and structure, as a function of time delays between the three pulses involved, we extract the dephasing time of the wave packet on the excited state. The dephasing time, measured as a function of time delay after pump excitation, shows oscillations indicating oscillatory wave packet dynamics on the excited state. Finally, from the experimental measurements and supporting theoretical calculations, we deduce that the wave packet completely leaves the S 1 state potential energy surface after three traversals of the intersystem crossing between the singlet S 1 and triplet T 2 states.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Online data-enabled predictive control

We develop an online data-enabled predictive (ODeePC) control method for optimal control of unknown systems, building on the recently proposed DeePC (Coulson et al., 2019). Our proposed ODeePC method leverages a primal-dual algorithm with real-time measurement feedback to iteratively compute the corresponding real-time optimal control policy as system conditions change. The proposed ODeePC conceptual-wise resembles standard adaptive system identification and model predictive control (MPC), but it provides a new alternative for the standard methods. ODeePC is enabled by computationally efficient methods that exploit the special structure of the Hankel matrices in the context of DeePC with Fast Fourier Transform (FFT) and primal-dual algorithm We provide theoretical guarantees regarding the asymptotic behavior of ODeePC, and we demonstrate its performance through numerical examples.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

The ultrafast pixel array camera system and its applications in high energy density physics

Diagnostics in high energy density physics, shock physics, and related fields are primarily driven by a need to record rapidly time-evolving signals in single-shot events. These measurements are often limited by channel count and signal degradation issues on cable links between the detector and digitizer. Here we present the Ultrafast Pixel Array Camera (UPAC), a compact and flexible detector readout system with 32 waveform-recording channels at up to 10 Gsample/s and 1.8 GHz analog bandwidth. The compact footprint allows the UPAC to be directly embedded in the detector environment. A key enabling technology is the PSEC4A chip, an eight-channel switch-capacitor array sampling device with up to 1056 samples/channel. The UPAC system includes a high-density input connector that can plug directly into an application-specific detector board, programmable control, and serial readout, with less than 5 W of power consumption in full operation. We present the UPAC design and characterization, including a measured timing resolution of ~20 ps or better on acquisitions of sub-nanosecond pulses with minimal system calibrations. Example applications of the UPAC are also shown to demonstrate operation of a solid-state streak camera, an ultrafast imaging array, and a neutron time-of-flight spectrometer.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Online Data-Enabled Predictive Control

We develop an online data-enabled predictive (ODeePC) control method for trajectory tracking of unknown systems, building upon the recently proposed DeePC. Our proposed ODeePC method leverages a primal-dual algorithm with real-time measurement feedback to iteratively compute the corresponding real-time optimal control policy as system conditions change. Specifically, our developed ODeePC: a) records data from the unknown system and updates the underlying primal-dual algorithm dynamically, b) can track changes in the system's operating point and adjust the control inputs, and c) is computationally efficient as it deploys a Fast Fourier Transform-based algorithm enabling the fast computation of the product of a non-square Hankel matrix with a vector. We provide theoretical guarantees regarding the asymptotic behavior of ODeePC and demonstrate its performance through a power system application.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2020

Improvement of Quantification in Non-Destructive Characterization of Radioactive Waste Packages -Introduction to the Ideas of a Currently Started Project - 20197

For the characterization of radioactive waste packages (e.g. 200-L drums) with inhomogeneous activity and density distributions preferably non-destructive methods like segmented gamma scanning and transmission measurements are applied. While the first is used for identification of the radioactive inventory, both are necessary for a reliable activity quantification. Although at nuclear facilities, segmented gamma scanner are state-of-the-art and are mostly equipped with a vertically moveable transmission source the combining of this data and further a-priori information improving accuracy in data estimation giving realistic, reliable and traceable uncertainty estimations are improvable. This challenge is tackled by a R and D project funded by the German Federal Ministry of Education and Research (BMBF). The boundary conditions for this project are (i) taking into account the typical instrumentation available at nuclear facilities, (ii) minimize the overall measurement time and (iii) combining data from emission and transmission measurements by Bayesian methods. For the R and D project, being still in its initial stage, the basic ideas, the data used for evaluation and the result of a preliminary investigation demonstrating the proof of principle are presented. Additionally, some first aspects on spatial resolution in emission and transmission measurements are addressed. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Network-Scale Ubiquitous Volume Estimation Using Tree-Based Ensemble Learning Methods

Currently ubiquitous volume data for roadway networks remains the key missing dimension in traffic operations. Most volume data are average annual daily traffic (AADT) measures derived from the Highway Performance Monitoring System (HPMS). Although methods to factor the AADT to hourly averages for typical day of week exist, actual volume data is limited to a sparse collection of locations in which volumes are continuously recorded. This paper/poster explores the use of state-of-art machine learning techniques to estimate accurate volume measures that span the highway network providing ubiquitous coverage in space, and point-in-time measures for a specific date and time. Three tree-based ensemble learning models, random forest (RF), gradient boost machine (GBM), and extreme gradient boost (XGBoost), were tested for volume estimation by learning from combined dataset of commercial probe data provided by TomTom, the FHWA's Travel Monitoring Analysis System (TMAS) data, and other infrastructure attributes such as number of lanes, speed limit, and weather. The methods were tested on major corridors and freeways in the metropolitan area of Denver. All three machine learning methods were able to provide hourly volume estimates 24 hours a day, 7 days a week, and 365 days a year with around 18% mean absolute error to true volume and about 5% of error with respect to roadway capacity. The low error measures allow the potential application by transportation agencies.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2023

Time-Delay Cosmography: Spectroscopy of Galaxies in the Environment of the J1537 Lensed Quasar System

Due to their sufficient distances and prevalence, lensed quasars have been a key site for research in gravitational lensing. In particular, researchers are interested in constraining Hubble's constant by measuring time delays in the arrival times of multiply imaged quasars. However, a lens model will need to be created that accounts for not just the lensing galaxy, but also any perturbers nearby that could affect the light path. Here, the J1537-3010 lensed quasar environment is investigated, and redshifts of 62 targets have been identified using Gemini IRAF and RASCAL. The success rate is roughly 45% across all four masks, less than the expected 60%-70%. We expect that masking out a bad amplifier contributed to the lower redshift measurement rates, as well as potentially poor viewing conditions during observation. With these redshifts, flexion shifts can be measured to determine if the observed target should be included in the lens model. An accurate lens model is fundament al for constraining the measurements of the time-delays of the quasar images and, thereby, constraining measurements in Hubble’s constant.

Kharchilava, George V.↗
DOE OSTI2024

Technology and times scales in Photonic Doppler Velocimetry (PDV)

Photonic Doppler Velocimetry (PDV) is a fiber-based measurement amenable to a wide range of experimental conditions. Interference between two optical signals—one Doppler shifted and the other not—is the essential principle in these measurements. A confluence of commercial technologies, largely driven by the telecommunication industry, makes PDV particularly convenient at near-infrared wavelengths. This discussion considers how measurement time scales of interest relate to the design, operation, and analysis of a PDV measurement, starting from the steady state through nanosecond resolution. Benefits and outstanding challenges of PDV are summarized, with comparisons to related diagnostics.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Embedded Fiber Bragg Grating (FBG) Sensors Fabricated by Ultrasonic Additive Manufacturing for High-Frequency Dynamic Strain Measurements

This article demonstrates high-frequency dynamic strain measurements using fiber Bragg grating (FBG) sensors embedded in metal parts. Using an ultrasonic additive manufacturing (UAM) process, FBGs inscribed in polyimide coated optical fibers were embedded in aluminum parts. An electromagnetic shaker was used to exert dynamic events on the embedded FBG sensors with frequencies from 1 to 10 kHz. The high-speed interrogation of FBG sensors was accomplished using a tunable vertical-cavity surface-emitting laser (VCSEL) and a high-speed interrogation system sampling at 120 kHz. The strain response measured by the FBG sensors was compared with real-time measurements using a laser velocimeter. A finite-element analysis (FEA) was performed to simulate responses to both static strain and high-frequency dynamic strain. In conclusion, results show that strains as small as 2.5$με$ can be resolved at frequencies up to 10 kHz.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Biogenic Emissions and Aerosol Response on the North Slope (BEAR-oNS) Field Campaign Report

Climate in the Arctic is changing at a rapid pace. When vegetation reacts to these changes, chemicals called biogenic volatile organic compounds (BVOCs) can be released into the atmosphere in new ways. This project seeks to investigate how climate change affects the quantity and type of BVOCs released into the atmosphere on the North Slope of Alaska (NSA). In addition, we are interested in the chemical reactions these BVOCs undergo in the arctic atmosphere. Project goals will be accomplished through field work on the NSA at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility’s observatory in Utqiagvik, real-time measurements, and collection and laboratory analysis of atmospheric aerosol samples.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Verification and Performance Impact of the New Parallel MCNP6.3 Particle Track Output Capability for Subcritical Multiplication Simulations

The MCNP6® code, version 6.3, has several new features that are intended to ultimately replace legacy features that are now marked for deprecation. One of these features is the new particle track output (PTRAC) format and capability, where the legacy PTRAC capability still exists alongside the modern PTRAC capability in MCNP6.3. While the MCNP6.3 code has been extensively verified and validated for many applications, the PTRAC feature is not exercised in any of the typical verification and validation (V&V) applications studied during the course of a typical MCNP code release. The primary goal of this paper is to verify that the legacy and modern PTRAC feature produces equivalent results for subcritical multiplication benchmarks previously studied. In the process of verifying that the simulated benchmark results are equivalent, the computational performance is compared between the legacy and modern PTRAC uses. In addition to verification of the update, which is important to the community as a whole, this effort also supports advances in the simulation of recent subcritical neutron noise measurements that require higher computational effort per second of real-time measurement than that of systems typically measured.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

The CLAS12 Backward Angle Neutron Detector (BAND)

The Backward Angle Neutron Detector (BAND) of CLAS12 detects neutrons emitted at backward angles of 155° to 175°, with momenta between 200 and 600 MeV$/c_0$. It is positioned 3-m upstream of the target, consists of 18 rows and 5 layers of 7.2-cm by 7.2-cm scintillator bars, and read out on both ends by PMTs to measure time and energy deposition in the scintillator layers. Between the target and BAND there is a 2-cm thick lead wall followed by a 2-cm veto layer to suppress gammas and reject charged particles. This paper discusses the component-selection tests and the detector assembly. Timing calibrations (including offsets and time-walk) were performed using a novel pulsed-laser calibration system, resulting in time resolutions better than 250 ps (150 ps) for energy depositions above 2 MeV (5 MeV). Cosmic rays and a variety of radioactive sources were used to calibration the energy response of the detector. Scintillator bar attenuation lengths were measured. We report the time resolution results in a neutron momentum reconstruction resolution, $δp/p$ < 1.5% for neutron momentum 200 ≤ $p$ ≤ 600 MeV/c. Final performance of the BAND with CLAS12 is shown, including electron–neutral particle timing spectra and a discussion of the off-time neutral contamination as a function of energy deposition threshold.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗