Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “compound events”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Elucidation of Structure and Physical Properties of Pyrolytic Sugar Oligomers Derived from Cellulose Depolymerization/Dehydration Reactions: A Density Functional Theory Study

Fast pyrolysis of lignocellulosic materials is a promising research area to produce renewable fuels and chemicals. Dehydration is known to be among the most important reaction families during cellulose pyrolysis; water is the most important product. Together with water, dehydration reactions also form a range of poorly known oligomer species of varying molecular sizes, often collected as part of bio-oil water-soluble (WS) fraction. In this work, we used electronic structure calculations to evaluate the relative thermodynamic stabilities of several oligomer species resulting from up to three consecutive dehydration events from cellulose depolymerization intermediates. A library of the thermodynamically favored candidate molecular structures was compiled. Results revealed that most of the water molecules are eliminated from the non-reducing end, forming thermodynamically more stable conjugated compounds. This is consistent with results reported by other researchers in literature where dehydration reactions occur preferably at the non-reducing ends of oligomers. The physical-chemical properties of the proposed structures were estimated using quantitative structure-property relationships (QSPRs) and quantitative property-property relationships (QPPRs). The anhydro-sugars derived from cellulose are often blamed for coke formation during bio-oil hydrotreatment. Understanding their chemical structure could help to develop rational strategies to mitigate coke formation. Furthermore, the thermo-physical properties reported (boiling point, melting point, Gibb’s free energy of formation, enthalpy of formation, and solubility parameters among others) are also fundamental to conducting first principle engineering calculations to design and analyze new pyrolysis reactors and bio-oil up-grading units.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Compounding effects of Lake and urbanization on summer precipitation in the Greater Chicago area

Here, this study explores the impacts of Lake Michigan and Chicago's urbanization on precipitation patterns over the Greater Chicago Area, using 22 years of observational data and Weather Research and Forecasting (WRF) model simulations focused on an early summer rain event. Observational analysis reveals that urban areas consistently experience more precipitation than the adjacent southern Lake Michigan region throughout the year, particularly before 2015. However, this disparity has narrowed since 2016 due to a more rapid increase in heavy precipitation over the lake compared to urban areas. Specifically, lake precipitation has risen by 25 mm per year, compared to 15 mm per year over urban areas. Additionally, the number of days with precipitation exceeding 5 mm per day has been rising at a rate of 1.34 days per year over the lake and 0.84 days per year over urban areas. Modeling experiments reveal that both urbanization and lake effects, including lake breezes, enhance precipitation over urban areas, primarily through convergence induced by interactions between land and lake breezes. In contrast, these same factors suppress precipitation over the lake. The suppression results from Lake Michigan's stable environment, characterized by cooler surface temperatures, limited evaporation in early summer, and a high-pressure anomaly over the lake driven by urban heating, which creates upward motion over urban areas and downward motion over the lake, further influencing precipitation patterns.

Coastal urban↗
DOE OSTI2025

Versatile & Intelligent Biodetection via Environmental Sensing (VIBES)

Reactive health monitoring strategies during events like the COVID-19 pandemic highlighted the need for predictive, threat-agnostic diagnostics that can detect both known diseases and novel chemical or biological threats. To address this, we investigated an optical biosensor as a breath volatile organic compound (VOC) analyzer, aiming to emulate biological olfaction. We assembled and validated the device with thin film metal coated substrate-based sensors. We immobilized small biological recognition elements on the substrates and delivered controlled concentrations of target VOCs. The sensor was irradiated with a visible laser and the sensor signal was recorded. We characterized the laser performance and tested 3 recognition elements for 2 VOCs with varying concentrations (1-100 ppm). We also evaluated enhancement of the signal using nanostructures on the metal film in comparison with planar film substrate. We demonstrated detecting ethanol reliably at concentrations as low as ~2 ppm along with preliminary detection of acetone (<100 ppm). We also found several unexpected factors that influence the sensor behavior that should be addressed to further refine the device’s performance. The nanostructures were, as expected, found to amplify the sensor signals. These findings demonstrate the feasibility of the optical bio-sensing modality for breath VOC monitoring at physiologically relevant levels. This positions LLNL to develop a low-cost, scalable, broad-spectrum health monitoring capability aligned with the Early Detection thrust of the Bioresilience Mission Focus Area and attract external funding.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Experimental and Computational Studies of Crystal Nucleation in Composition Gradients (Final Report)

The major goals of this project were to develop and validate a predictive nucleation model that incorporates composition gradients and is applicable to a large range of metallic systems which form both stochiometric and non-stochiometric compounds. Computationally we planned to expand the extent of thermodynamics-based theories and lay the groundwork to improve the general understanding and predictive capabilities of the role that gradients play in phase formation, glass formability and stability, and nucleation and growth events. To address these goals, we used Molecular Dynamics (MD) simulations and both isothermal and isochronal nanocalorimetric experiments on amorphous phases with a controlled composition gradient with the hopes of validating and improving the classical nucleation model and its use in solid solutions. While the computations were successful and identified ways to improve the classical nucleation model, the in situ nanocalorimetry studies proved very challenging due to unexpected difficulties in fabricating effective calorimeters and samples. Thus, we could not experimentally validate our predicted influence of composition gradients on nucleation. Nonetheless, important insights were gained and modifications to the classical nucleation theory were suggested.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Upper Limit for the 248 Cm( 50 Ti, x n) 298− x Og Reaction Cross Section

After the synthesis of element 113, nihonium (Nh) via the 209 Bi( 70 Zn,n) 278 Nh cold fusion reaction using the RIKEN heavy-ion Linear ACcelerator (RILAC) and the GAs-filled Recoil Ion Separator (GARIS), the search for the heaviest isotopes of oganesson was initiated with GARIS-II by means of the 248 Cm( 50 Ti,xn) 298−x Og fusion evaporation reaction. The optimal bombarding energy for the 50 Ti + 248 Cm reaction was determined from the quasielastic barrier distribution extracted from the excitation function of quasielastic backscattering. Here, this method optimizes the compound nucleus formation. The search for Og was conducted for 39 days on the basis of the experimentally derived 50 Ti beam energy of 227.9(5) MeV at the middle of 248 Cm target. A precise analysis of the dataset based on multiple event search strategies revealed no decay chains with a total dose on 248 Cm target of 4.93 × 10 18 50 Ti projectiles, reaching a sensitivity of 0.27 pb and a 1σ upper cross section limit of 0.50 pb.

Gall, Benoît Jean-Paul [University of Strasbourg (↗
DOE OSTI2024

Venturing Past Uranium: Synthesis of a Np(IV) Polyoxomolybdate–Alkoxide Sandwich Complex

The synthesis of a Np(IV) polyoxomolybdate– alkoxide sandwich complex, (TBA) 2 [Np{Mo 5 O 13 (OMe) 4 NO} 2 ] (TBA = tetrabutylammonium), is reported. This compound represents a rare example of a neptunium polyoxometalate cluster isolated outside of water, allowing for characterization of its electrochemical properties in nonaqueous solvents. Complexation of An(IV) cations fine-tunes the redox properties of the cluster, with the observed four reversible reductive events varying slightly both in potential and peak separation depending on the actinide present. The new Np(IV) complex also shows an irreversible event assigned to oxidation of Np(IV) to Np(V). New methodology for facile 17 O enrichment of (TBA) 2 [Mo 5 O 13 (OMe) 4 NO][Na(MeOH)] is presented, which provides a simple pathway to 17 O enriched analogues of the sandwich complexes discussed (Zr(IV), Hf(IV), Th(IV), U(IV), U(V), Np(IV)). 17 O NMR spectroscopy subsequently provides insights into both the nature of metal–oxygen bonding, as well as the influence of unpaired f-electrons on the local environment of the oxygen nuclei.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Preliminary Nuclear Containment Vessel Modeling for Multi-Hazard Probabilistic Risk Assessment under Seismic Hazards and Concrete Degradation

The current practice for natural phenomena hazards (NPH) risk assessment of nuclear facilities is to compute the risk for each hazard independently and then compound the total risk as a combination of single hazard risks. This state of practice does not consider correlations between hazards and the cascading impacts to structures, systems, and components (SSCs), and could thus underestimate the NPH risk or overestimate the nuclear facility safety. Events such as the Fukushima Daiichi accident have highlighted the importance of multi-hazard risk considerations to nuclear power plants (NPPs) that quantify the cascading damage effects to SSCs in the risk models. Moreover, the current fleet of NPPs in the United States is aging; these NPPs are now expected to operate well beyond their initially planned design life. Aging-related deterioration can potentially decrease the capacity of critical structures such as containment vessels to withstand NPH. Such aging considerations may not be adequately accounted for by the current NPH risk assessment guidelines. This paper presents a preliminary modeling and simulation of a representative reinforced concrete containment vessel subjected to seismic mainshock and aftershock considering concrete degradation due to alkali silica reaction. The broader aim is to develop multi-hazard time-dependent fragility functions that could be subsequently used in the probabilistic risk assessment (PRA) model. The multi-hazard component comes into play due to the consideration of damage to the containment vessel under seismic loads and concrete degradation. Consideration of concrete degradation also brings into play the time-dependent nature of the containment vessel response. The response of the containment vessel under varying degrees of concrete degradation to seismic loads is investigated. The results presented are simulated using the Multi-hazard Analysis for STOchastic time-DOmaiN phenomena (MASTODON) software for seismic analysis and the Blackbear software for concrete degradation and damage modeling. Both software are open source and developed within the Multiphysics Object-Oriented Simulation Environment (MOOSE).

42 ENGINEERING↗
DOE OSTI2025

Ascorbic Acid Stability and pH Testing to Support RWM-018 Pilot Scale Wellhead Treatment System Feasibility Determination

A multitude of groundwater remediation techniques for chlorinated volatile organic compounds (cVOCs) have been conducted at the A/M-Areas of the Savannah River Site (SRS). Historical in-situ chemical oxidation (ISCO) injections of potassium permanganate and sodium persulfate conducted in 2018 and 2020, have left residual oxidant concentrations in the A/M-Area groundwater system. ISCO events targeted dense non-aqueous phase liquids (DNAPLs) through the injection of strong oxidants within plume zones upgradient of current groundwater recovery wells RWM-008 and RWM-018. These residual oxidants could significantly impede the operation of the mercury removal system needed to meet National Pollutant Discharge Elimination System (NPDES) permit requirements for the ongoing pump-and-treat system that hydraulically controls potions of the A/M-Area plume. Effluent treated groundwater from this system is discharged to surface water at the receiving outfall of the M-1 Air Stripper. To prevent interference of the M-1 Air Stripper system by residual oxidants, groundwater recovery has been ceased at well RWM-018. Modeling of oxidant transport in A/M-Area from ISCO estimated that the potential oxidant load contributed by RWM-018 could be as high as 120 mg/L. It is also possible that oxidants may be contributed via pumping at well RWM-008 in the near future as residual oxidants within the aquifer migrate toward its zone of influence. Savannah River National Laboratory (SRNL) has conducted research to investigate potential pre-treatment chemicals to neutralize these residual oxidants, before reaching the M-1 Air Stripper, to allow for resumed groundwater recovery at RWM-018 and continued pumping at RWM-008. Deployment of ascorbic acid for neutralization of residual oxidants at RWM-018 (and possibly RWM-008) is recommended based on results from previous reductant testing (SRNL, 2021). For a maximum estimated oxidant load at RWM-0018, a well-head treatment system would need to dose about 400 gallons of ascorbic acid each month to ensure complete neutralization. A second system with additional reagent should also be considered for deployment at RWM-008.

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

Structure-guided approach to modulate small molecule binding to a promiscuous ligand-activated protein

Ligand-binding promiscuity in detoxification systems protects the body from toxicological harm but is a roadblock to drug development due to the difficulty in optimizing small molecules to both retain target potency and avoid metabolic events. Immense effort is invested in evaluating metabolism of molecules to develop safer, more effective treatments, but engineering specificity into or out of promiscuous proteins and their ligands is a challenging task. To better understand the promiscuous nature of detoxification networks, we have used X-ray crystallography to characterize a structural feature of pregnane X receptor (PXR), a nuclear receptor that is activated by diverse molecules (with different structures and sizes) to up-regulate transcription of drug metabolism genes. We found that large ligands expand PXR’s ligand-binding pocket, and the ligand-induced expansion occurs through a specific unfavorable compound-protein clash that likely contributes to reduced binding affinity. Removing the clash by compound modification resulted in more favorable binding modes with significantly enhanced binding affinity. We then engineered the unfavorable ligand-protein clash into a potent, small PXR ligand, resulting in marked reduction in PXR binding and activation. Structural analysis showed that PXR is remodeled, and the modified ligands reposition in the binding pocket to avoid clashes, but the conformational changes result in less favorable binding modes. Thus, ligand-induced binding pocket expansion increases ligand-binding potential of PXR but is an unfavorable event; therefore, drug candidates can be engineered to expand PXR’s ligand-binding pocket and reduce their safety liability due to PXR binding.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Yet Another Hauser-Feshbach Code

Code framework to perform simulations of nuclear reactions with incident particles including gammas, protons, neutrons, deuterons, tritons, helium-3, and alphas to develop nuclear data libraries and study nuclear reaction phenomona. The code can model nuclear reactions or initial populations specified by the user. The decays principally follow the compound-nucleus hypothesis and the statistical decay of Hauser and Feshbach. The code models nuclear decays with a Monte Carlo process that tracks the decay of each state. Data libraries are produced that can be translated into GNDS (generalized Nuclear Data Structure). YAHFC can also be used as an event generator, with individual decays written to disk for offline analysis. Both serial and MPI versions are provided. YAHFC does NOT perform transport of nuclear reactions through materials, only the primary reaction with a target material.

Ormand, WilliamE.↗
DOE OSTI2023

Source apportionment of soot particles and aqueous-phase processing of black carbon coatings in an urban environment

Abstract. The impacts of soot particles on climate and human health depend on the concentration of black carbon (BC) as well as the thickness and composition of the coating material, i.e., organic and inorganic compounds internally mixed with BC. In this study, the size-resolved chemical composition of BC-containing aerosol was measured using a high-resolution soot particle aerosol mass spectrometer (SP-AMS) during wintertime in Fresno, California, a location influenced by abundant combustion emissions and frequent fog events. Concurrently, particle optical properties were measured to investigate the BC absorption enhancement. Positive matrix factorization (PMF) analysis was performed on the SP-AMS mass spectral measurements to explore the sources of soot particles and the atmospheric processes affecting the properties of BC coatings. The analysis revealed that residential woodburning and traffic are the dominant sources of soot particles. Alongside primary soot particles originating from biomass burning (BBOABC) and vehicles (HOABC) two distinct types of processed BC-containing aerosol were identified: fog-related oxidized organic aerosol (FOOABC) and winter-background OOABC (WOOABC). Both types of OOABC showed evidence of having undergone aqueous processing, albeit with differences. The concentration of FOOABC was substantially elevated during fog events, indicating the formation of aqueous secondary organic aerosol (aqSOA) within fog droplets. On the other hand, WOOABC was present at a relatively consistent concentration throughout the winter and was likely related to the formation of secondary organic aerosol (SOA) in both the gas phase and aerosol liquid water. By comparing the chemical properties and temporal variations in FOOABC and WOOABC, we gain insights into the key aging processes of BC aerosol. It was found that aqueous-phase reactions facilitated by fog droplets had a significant impact on the thickness and chemical composition of BC coatings, thereby affecting the light absorption and hygroscopic properties of soot particles. These findings underscore the important role of chemical reactions occurring within clouds and fogs and influencing the climate forcing of BC aerosol in the atmosphere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Active mechanisorption driven by pumping cassettes

Pumping macrocycles onto surfaces Numerous chemical processes, ranging from water purification to catalysis, involve sorption of small molecules onto surfaces. Typically, spontaneous attractive interactions favor the binding event. Feng et al . report a mechanisorption process that requires redox manipulations to pump macrocycles from bulk solution onto axles immobilized on a metal-organic framework. The resulting rotaxanes store energy through nonequilibrium charge concentration in their mechanical bonds. Ultimately, the technique could also prove useful for actively partitioning compounds with particular functionality between surface and bulk environments. —JSY

Science & Technology - Other Topics↗
DOE OSTI2025

WRF-Chem & Data Assimilation: Reconstructing a Historic Dispersion Event

CONCLUSIONS • For this particular case and use, 3D-VAR was the most useful data assimilation method applied for modeling this plume. • Slight downside was the plume was modeled to move too quickly. • Whether this result is generalizable may be debatable based on the circumstances. • The atmospheric state altered how effective the data assimilation algorithms performed. • Nudging and 3D-VAR are not mutually exclusive, but their errors for wind speed may compound

Thomas, Andrew M. [Savannah River National Laborat↗
DOE OSTI2024

Regulatory Treatment of Low Frequency External Events under a Risk-Informed Performance-Based Licensing Pathway: Safety Criteria Evaluation

There has been recent progress in the development of risk-informed performance-based (RIPB) design and licensing approaches, which leverage the insights gained from detailed risk assessments and utilize performance-based metrics to permit flexibility and innovation. The RIPB approaches have included the probabilistic treatment of external hazards, including low frequency events that are beyond the design basis. A preceding study conducted in FY21 noted that there are certain challenges to the probabilistic treatment of low frequency external events, which are primarily the result of uncertainty in the hazard curve and the associated plant response to rare, severe events. The current work expands on the previous study by examining the regulatory safety criteria contained within draft 10 CFR Part 53 and associated draft RIPB seismic design guidance. The evaluation identified potential challenges in demonstrating satisfaction of the safety criteria for low frequency external events, with specific difficulties associated with demonstrating compliance with cumulative safety criteria metrics, such as the quantitative health objectives (QHOs). Non-LWRs are expected to utilize the direct calculation of offsite consequence, rather than use surrogates, for comparison to the QHOs, which can be particularly challenging as the previously identified uncertainties are compounded by uncertainties in the response of the neighboring population. The current work details this evaluation and key findings. The central recommendation from this effort is that it is necessary to develop an approach for demonstrating compliance with the safety criteria in draft Part 53 that addresses the key challenges while providing flexibility to applicants.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2026

Compound flood simulations indicate rising public exposure to sewage-contaminated waters in Waikīkī, Hawai‘i

Waikīkī, Hawai‘i serves as a valuable case study for flood vulnerability due to its low elevation, present-day exposure to multiple flood sources, and role as the state’s economic engine. This study applies the high-resolution, open-source WRF-Hydro-CUFA (Coastal Urban Flood Application) model to simulate compound flood interactions among pluvial, fluvial, coastal, storm drain-driven, and subsurface processes, and to evaluate how flood characteristics in Waikīkī evolve under projected sea-level rise (SLR). Simulated water levels in an estuarine drainage canal, serving as the primary outlet for gravity-flow drainage from Waikīkī, show strong agreement with observations (r ≥ 0.935, R 2 ≥ 0.874), accurately reproducing flooding observed during recent 5-year and 50-year storm events. Simulations incorporating SLR demonstrate a shift in dominant flood drivers as sea levels rise. In addition, results identify critical thresholds at which elevated estuarine tailwater conditions cause widespread drainage backflow, eventually occurring in the absence of rainfall. These findings suggest that tidally driven flooding will progressively dominate over rainfall-driven events, increasing public exposure to highly contaminated canal and groundwater sources. The results underscore the urgent need to integrate water quality issues and drainage failure into coastal flood management strategies for low-lying urban environments, particularly those reliant on polluted estuarine waterways for stormwater management.

Compound flooding↗
DOE OSTI2022

BayoTech Risk and Modeling Support of NM Gas Site

The BayoTech hydrogen generation system has been evaluated in terms of safety considerations at the NM Gas site. The consequence of a leak in different components in the system was evaluated in terms of plume dispersion and overpressure. Additionally, the likelihood of a leak scenario for different hydrogen components was identified. The worst-case plume dispersion cases, full-bore leaks, resulted in relatively large plumes. However, these cases were noted to be far less likely than the partial break cases that were evaluated. The partial break cases resulted in nearly negligible plume lengths. Similarly, the overpressure analysis of the full-bore break scenarios resulted in much larger overpressures than the partial break cases (which resulted in negligible overpressure at the lot line). There were several cases evaluated in the analysis that represented leak scenarios from both hydrogen and natural gas sources. Generally, the natural gas leak scenarios resulted in a smaller horizontal impact than that of hydrogen leaks. The worst-case consequence from a hydrogen leak resulted from the compressors, storage pods, or dispensing system. To consider the safety features that may isolate the leak, the consequence was evaluated at different times after the leak event to show the reduction of pressure. After 2 seconds, the plume dispersion from this event is contained within the perimeter of the site. The worst-case consequences show that the plume may disperse to adjacent facilities and to the street. When considering both likelihood and consequence, the risk may be considered low because the maximum frequency of a full-bore leak from any component within the hydrogen compound is 8.2 E-5/yr. This means that a full-bore leak is expected to occur less than once every 10,000 years. The risk can be further reduced by implementing mitigative countermeasures, such as CMU walls along the sides of the equipment compound. This would reduce the overall consequence of the worst-case dispersion scenarios (horizontal impact of plume). In terms of siting and safety analysis, the NFPA 2 code was used to provide a high-level evaluation of the current site plan. The most limiting equipment in terms of set-back distance are the compressors/storage units because of the high-pressure hydrogen. The site layout was evaluated for an acceptable location for the compression/storage unit based on NFPA 2 set-back distances. It is important to note that the NFPA 2 set-back distances consider both likelihood and consequence. This is important because the worst-case results evaluated herein also represent the least likely leak scenario. Other site-specific considerations were evaluated, including the parking shade structure with photovoltaic cells and refueling vehicles. These issues were dispositioned and determined to not present a safety risk.

08 HYDROGEN↗
DOE OSTI2024

Algorithmically detected rain-on-snow flood events in different climate datasets: a case study of the Susquehanna River basin

Abstract. Rain-on-snow (RoS) events in regions of ephemeral snowpack – such as the northeastern United States – can be key drivers of cool-season flooding. We describe an automated algorithm for detecting basin-scale RoS events in gridded climate data by generating an area-averaged time series and then searching for periods of concurrent precipitation, surface runoff, and snowmelt exceeding predefined thresholds. When evaluated using historical data over the Susquehanna River basin (SRB), the technique credibly finds RoS events in published literature and flags events that are followed by anomalously high streamflow as measured by gauge data along the river. When comparing four different datasets representing the same 21-year period, we find large differences in RoS event magnitude and frequency, primarily driven by differences in estimated surface runoff and snowmelt. Using dataset-specific thresholds improves agreement between datasets but does not account for all discrepancies. We show that factors such as meteorological forcing and coupling frequency, as well as choice of land surface model, play roles in how data products capture these compound extremes and suggest care is to be taken when climate datasets are used by stakeholders for operational decision-making.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

A North Carolina Retrospective: Major Outage Event Trends & Hurricane Helene using TASTI-GRID

The impacts of Hurricane Helene in September of 2024 showed magnifying effects on the number of major power outages reported both during and after the catastrophic weather event. The affected areas on the western edge of North Carolina, particularly Buncombe County (Asheville), endured a disproportionate number of outage impacts than surrounding counties atop the Piedmont Plateau. In 2024, each of the counties with the highest frequency of major outage events received at least one category of FEMA Disaster Declaration following Hurricane Helene. While the storm’s impacts certainly skewed 2024’s yearly major outage frequencies, we use TASTI-GRID to identify existence resilience challenges in the years prior to 2024 that may have given way to understanding how geography, topography, population density and other factors have compounding effects on existing resilience challenges in Buncombe and Mecklenburg counties, specifically.

24 POWER TRANSMISSION AND DISTRIBUTION↗