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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Regulatory framework for NORM residues in Belgium

The Belgian radiation protection authority (Federal Agency for Nuclear Control - FANC) has published in March 2013 a decree regulating the acceptance of NORM residues by nonradioactive waste treatment facilities. This regulation is based on the concept of 'work activities involving natural radiation sources' in the sense of article 40 of the 96/29/EURATOM directive. The disposal or processing facilities which accept NORM residues with an activity concentration above a generic exemption level will be considered as 'work activities' and submitted to declaration according to the Belgian radiation protection regulations. On basis of this declaration, specific acceptance criteria for the different types of processing/ disposal of the residues (disposal on landfill, recycling into building materials, etc.) are imposed. FANC has drafted guidelines for these acceptance criteria. A methodological guide for the operators of the concerned facilities was also published. Moreover, sites where significant quantities of NORM residues are or have been disposed, are subjected to an environmental monitoring in the framework of the national program of radiological surveillance of FANC. FANC also introduced in its regulations the concept of anthropogenic radon-prone areas: e.g. former phosphogypsum stacks have been defined as anthropogenic radon-prone areas, which allows some form of regulatory control of these sites. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Application of a new model of residual magnetization of iron for calculating the deflecting magnet of an accelerator

Allowing for residual magnetization of iron is necessary when calculating the magnetic field of elements of electron-optical channels in charged-particle accelerators because the contribution of residual magnetization to the field in the gap can be on the order of mT. Moreover, the magnitude and sign of this contribution depend on the magnetization process. Earlier, we proposed a model of residual magnetization of iron with the use of a small number of magnetic domain types. Here, an algorithm for magnetic-field calculation with the use of this model is described. The ability of the algorithm was demonstrated for the case of a simplest electromagnet with an O-shaped magnetic circuit. Comparison with the measurement results demonstrated a satisfactory accuracy of allowing for residual magnetization.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Conserved active site cysteine residue of archaeal THI4 homolog is essential for thiamine biosynthesis in Haloferax volcanii

Thiamine (vitamin B1) is synthesized de novo by certain yeast, fungi, plants, protozoans, bacteria and archaea. The pathway of thiamine biosynthesis by archaea is poorly understood, particularly the route of sulfur relay to form the thiazole ring. Archaea harbor structural homologs of both the bacterial (ThiS-ThiF) and eukaryotic (THI4) proteins that mobilize sulfur to thiazole ring precursors by distinct mechanisms. Results: Based on comparative genome analysis, halophilic archaea are predicted to synthesize the pyrimidine moiety of thiamine by the bacterial pathway, initially suggesting that also a bacterial ThiS-ThiF type mechanism for synthesis of the thiazole ring is used in which the sulfur carrier ThiS is first activated by ThiF-catalyzed adenylation. The only ThiF homolog of Haloferax volcanii (UbaA) was deleted but this had no effect on growth in the absence of thiamine. Usage of the eukaryotic THI4-type sulfur relay was initially considered less likely for thiamine biosynthesis in archaea, since the active-site cysteine residue of yeast THI4p that donates the sulfur to the thiazole ring by a suicide mechanism is replaced by a histidine residue in many archaeal THI4 homologs and these are described as D-ribose-1,5-bisphosphate isomerases. The THI4 homolog of the halophilic archaea, including Hfx. volcanii (HVO_0665, HvThi4) was found to differ from that of methanogens and thermococci by having a cysteine residue (Cys165) corresponding to the conserved active site cysteine of yeast THI4p (Cys205). Deletion of HVO_0665 generated a thiamine auxotroph that was trans-complemented by a wild-type copy of HVO_0665, but not the modified gene encoding an HvThi4 C165A variant. Based on our results, we conclude that the archaeon Hfx. volcanii uses a yeast THI4-type mechanism for sulfur relay to form the thiazole ring of thiamine. We extend this finding to a relatively large group of archaea, including haloarchaea, ammonium oxidizing archaea, and some methanogen and Pyrococcus species, by observing that these organisms code for THI4 homologs that have a conserved active site cysteine residue which is likely used in thiamine biosynthesis. Thus, archaeal members of IPR002922 THI4 family that have a conserved cysteine active site should be reexamined for a function in thiamine biosynthesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Identification of the nucleophile catalytic residue of GH51 α-l-arabinofuranosidase from Pleurotus ostreatus

In this paper, the recombinant α-l-arabinofuranosidase from the fungus Pleurotus ostreatus (rPoAbf) was subjected to site-directed mutagenesis in order to identify the catalytic nucleophile residue. Based on bioinformatics and homology modelling analyses, E449 was revealed to be the potential nucleophilic residue. Thus, the mutant E449G of PoAbf was recombinantly expressed in Pichia pastoris and its recombinant expression level and reactivity were investigated in comparison to the wild-type. The design of a suitable set of hydrolysis experiments in the presence or absence of alcoholic arabinosyl acceptors and/or formate salts allowed to unambiguously identify the residue E449 as the nucleophile residue involved in the retaining mechanism of this GH51 arabinofuranosidase. 1 H NMR analysis was applied for the identification of the products and the assignement of their anomeric configuration.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Data for Pilot-Scale Processing of Miscanthus x giganteus for Recovery of Anthocyanins Integrated with Production of Microbial Lipids and Lignin-Rich Residue

Chemical-free hydrothermal pretreatment of Miscanthus x giganteus (Mxg) at the lab scale using high liquid-to-solid ratios resulted in the recovery of anthocyanins and enhanced enzymatic digestibility of residual biomass. In this study, the process is scaled up by using a continuous hydrothermal pretreatment reactor operated at a low liquid-to-solid ratio (50 % w/w solids) as an important step towards commercialization. Anthocyanin yield was 70 % w/w at the pilot scale (50 kg of Mxg), compared to the 94 % w/w yield achieved at the lab scale (0.5 g of Mxg). The pretreated biomass was subsequently refined mechanically using a disc mill to increase the accessibility of cellulose by cellulases. Enzymatic saccharification of the pretreated and disc-milled residue yielded 238 g/L sugar concentration by operating in fed-batch mode at 50 % w/v solids content. Two strains of Rhodosporidium toruloides were evaluated for converting the hydrolysate sugars into microbial lipids, and strain Y-6987 had the highest lipid titer (11.0 g/L). Further, the residue left after enzymatic saccharification was determined to be enriched 1.7-fold in the lignin content. This lignin-rich residue has value as a feedstock for the production of sustainable aviation fuel precursors and other high-value lignin-based chemicals. Hence the proposed biorefinery based on Mxg creates an opportunity for generating revenue from multiple high-value products. As the demand for biofuels and biobased products is rising, the biorefinery products from Mxg would create a niche in the industrial sector.

Conversion↗
DOE OSTI2018

Public Acceptance of Pre-Commercial Thinning and Energy and Soil Amendment Products from Post-Harvest Residues in Western Forests of the United States

Abstract . The goals of the Waste-to-Wisdom project is to produce bioenergy products and biochar from post-harvest forest residues and thus understanding public acceptance of the forest management and utilizing forest residues for biomass-based products is critical. This research explores the public perceptions of producing bioenergy products and biochar from forest thinning activities in the western Pacific Northwest region. A web-based survey was conducted in Washington, Oregon, and Northern California generating 1,202 responses. Multinomial regression techniques and simulation-based approach were applied to analyze how demographic and socio-economic factors influence public perceptions. People living in less populated areas are more likely to support forest thinning. Higher levels of education and household income also lead to higher levels of support for forest thinning. On the other hand, supports for forest thinning results in supports for using forest residuals to produce bioenergy products. These results suggest that different strategies are necessary to effectively communicate the environmental and ecological benefits of using forest residuals derived from forest thinning activities to produce biomass-based products. Keywords: Environmental Perceptions, Multinomial Logistic Regression, Natural Resource Management, Rural vs. Urban, Simulation-Based Approach.

Agriculture↗
DOE OSTI2018

Strategies for Reducing Moisture Content in Forest Residues at the Harvest Site

Abstract. The moisture content (MC) of biomass derived from forest residues can pose a challenge to biomass utilization. It plays a significant role in determining the cost of transportation and subsequent market price. Additionally, emerging biomass conversion technologies, such as gasification, torrefaction, and briquetting, have very narrow specifications for the MC (e.g., <15%) in their feedstocks. The goal of this study was to develop strategies for reducing moisture content by evaluating different arrangement patterns of forest residues and its effect on MC reduction at the harvest site. The study compared four different arrangement patterns including criss-cross, teepees, traditional piling (processor piled), and scattered residues in three different timber harvest units in northern California. Two of the arrangement patterns (criss-cross and processor piled) were also covered with a plastic cover. Samples were collected from each treatment using a transect method and were recorded for 12 months. There was an overall drop of MC from 52% (freshly cut) to 12% between all arrangements over the study period. The cost of construction per pile, averaged $37, $41, and $48 for teepees, criss-cross, and processor piles, respectively. Even though, there was no significant difference in MC reduction between piles (except scattered), each pile arrangement of forest residues directly affected biomass feedstock operations, logistics, and costs. Keywords: Feedstock quality, Logging slash, Transect sampling method, Woody biomass energy.

Agriculture↗
DOE OSTI2016

Residual Viremia in Treated HIV+ Individuals

Antiretroviral therapy (ART) effectively controls HIV infection, suppressing HIV viral loads. However, some residual virus remains, below the level of detection, in HIV-infected patients on ART. Furthermore, the source of this viremia is an area of debate: does it derive primarily from activation of infected cells in the latent reservoir, or from ongoing viral replication? Our observations seem to be contradictory: there is evidence of short term evolution, implying that there must be ongoing viral replication, and viral strains should thus evolve. The phylogenetic analyses, and rare emergent drug resistance, suggest no long-term viral evolution, implying that virus derived from activated latent cells must dominate. We use simple deterministic and stochastic models to gain insight into residual viremia dynamics in HIV-infected patients. Our modeling relies on two underlying assumptions for patients on suppressive ART: that latent cell activation drives viral dynamics and that the reproductive ratio of treated infection is less than 1. Nonetheless, the contribution of viral replication to residual viremia in patients on ART may be non-negligible. However, even if the portion of viremia attributable to viral replication is significant, our model predicts (1) that latent reservoir re-seeding remains negligible, and (2) some short-term viral evolution is permitted, but long-term evolution can still be limited: stochastic analysis of our model shows that de novo emergence of drug resistance is rare. Thus, our simple models reconcile the seemingly contradictory observations on residual viremia and, with relatively few parameters, recapitulates HIV viral dynamics observed in patients on suppressive therapy.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Evaluation residual moisture in lithium-ion battery electrodes and its effect on electrode performance

Removing residual moisture in lithium-ion battery electrodes is essential for desired electrochemical performance. In this manuscript, the residual moisture in LiNi 0.5 Mn 0.3 Co 0.2 O 2 cathodes produced by conventional solvent-based and aqueous processing is characterized and compared. The electrochemical performance has also been investigated for various residual moisture contents. As a result, it has been demonstrated that the residual moisture lowers the first cycle coulombic efficiency, but its effect on short term cycle life is insignificant.

25 ENERGY STORAGE↗
DOE OSTI2018

Phosphorus Sorption to Aluminum‐based Water Treatment Residuals Reacted with Dairy Wastewater: 2. X‐Ray Absorption Spectroscopy

Phosphorus capture from wastewater can decrease water pollution and provide a P‐rich fertilizer alternative for use in agricultural production. This study was conducted to elucidate P retention mechanisms in Al‐based water treatment residuals (Al‐WTR) to gain insight regarding P sorption and the potential for P release from Al‐WTR after reaction with dairy wastewater. Synchrotron‐based microfocused X‐ray fluorescence (micro‐XRF) spectrometry, bulk P K ‐edge X‐ray absorption near edge structure spectroscopy (XANES), and P K ‐edge micro‐XANES spectroscopy were used to determine P distribution and speciation within the Al‐WTR materials. Bulk XANES analyses indicated a shift from ∼56 P atom % Ca‐associated P in the initial Al‐WTR to ∼32% P atom % Ca‐associated P after reaction with wastewater; Al‐associated P made up the remainder of the P species. According to XANES analyses, adsorption appeared to be the primary P retention mechanism in the Al‐WTR materials. However, micro‐XANES analyses depicted a more complicated picture of P retention mechanisms, with regions of primarily Al‐associated P, regions of primarily Ca‐associated P, regions of mixed Al‐ and Ca‐associated P, and distinct apatite‐ or octocalcium phosphate‐like P grains. Synchrotron micro‐XRF mapping further suggested that exposure of the aggregate exteriors to wastewater caused P to diffuse into the porous Al‐WTR aggregates. Organic P species were not explicitly identified via P K ‐edge XANES despite high organic matter content, suggesting that organic P may have been predominantly associated with mineral surfaces. Although diffusion and sorption to Al may decrease P bioavailability, Ca‐associated P may increase P bioavailability from Al‐WTR that is reused as a soil amendment. Core Ideas XAS provided unambiguous evidence of P associations with Al and Ca in water treatment residuals. Phosphorus adsorbed to Al and Ca surfaces in Al‐based water treatment residuals. Grains of apatite‐ or octocalcium phosphate‐like P were found in water treatment residuals. Phosphorus diffused into aggregates on reaction with P‐rich wastewater. Evidence from electron microscopy and XRD complemented these findings.

Massey, Michael S.↗
DOE OSTI2015

Determining the Release of Radionuclides from Tank Waste Residual Solids: FY2015 Report

Methodology development for pore water leaching studies has been continued to support Savannah River Site High Level Waste tank closure efforts. For FY2015, the primary goal of this testing was the achievement of target pH and Eh values for pore water solutions representative of local groundwater in the presence of grout or grout-representative (CaCO 3 or FeS) solids as well as waste surrogate solids representative of residual solids expected to be present in a closed tank. For oxidizing conditions representative of a closed tank after aging, a focus was placed on using solid phases believed to be controlling pH and E h at equilibrium conditions. For three pore water conditions (shown below), the target pH values were achieved to within 0.5 pH units. Tank 18 residual surrogate solids leaching studies were conducted over an E h range of approximately 630 mV. Significantly higher Eh values were achieved for the oxidizing conditions (ORII and ORIII) than were previously observed. For the ORII condition, the target Eh value was nearly achieved (within 50 mV). However, E h values observed for the ORIII condition were approximately 160 mV less positive than the target. E h values observed for the RRII condition were approximately 370 mV less negative than the target. Achievement of more positive and more negative E h values is believed to require the addition of non-representative oxidants and reductants, respectively. Plutonium and uranium concentrations measured during Tank 18 residual surrogate solids leaching studies under these conditions (shown below) followed the general trends predicted for plutonium and uranium oxide phases, assuming equilibrium with dissolved oxygen. The highest plutonium and uranium concentrations were observed for the ORIII condition and the lowest concentrations were observed for the RRII condition. Based on these results, it is recommended that these test methodologies be used to conduct leaching studies with actual Tank 18 residual solids material. Actual waste testing will include leaching evaluations of technetium and neptunium, as well as plutonium and uranium.

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

V&V of Residual Stress for GTS

Residual stresses induced during forging and welding can cause detrimental failure in reservoirs due to enhanced possibility of crack propagation. Therefore, reservoirs must be designed with yield strengths in a tight range. This report summarizes an effort to verify and validate a computational tool that was developed to aid in prediction of the evolution of residual stresses throughout the manufacturing process. The application requirements are identified and summarized in the context of the Predictive Capability Maturity Model (PCMM). The phenomena of interest that the model attempts to capture are discussed and prioritized using the Phenomena Identification and Ranking Table (PIRT) to identify any gaps in our approach. The fidelity of the modeling approach is outlined and details on the implementation and boundary conditions are provided. The code verification requirements are discussed and solution verification is performed, including a mesh convergence study on the series of modeling steps (forging, machining and welding). Validation activities are summarized, including validation of the displacements, residual stresses, recrystallization, yield strength and thermal history. A sensitivity analysis and uncertainty quantification are also performed to understand how variations in the manufacturing process affect the residual stresses.

42 ENGINEERING↗
DOE OSTI2020

High Order Implicit Residual-Based Spatial Discretization Error Estimation for S N Neutron Transport

This work demonstrates our novel residual source spatial discretization error estimator (LeR/TEAD) for a DGFEM-1 discretization and assesses it along with two contemporary estimators, Ragusa and Wang's h -refinement estimator (RW) and Duo, Azmy, and Zikatanov's explicit residual-based estimator (DAZ), on a suite of Method of Manufactured Solutions (MMS) 2D problems and three realistic problem geometries. LeR/TE-AD is attractive because it directly estimates the local error in the angular flux, as opposed to a mere indicator of the error's behavior, on the same mesh and method order as the original numerical solution, thus typically being less computationally intensive than a refinement-based method. On the MMS suite, LeR/TE-AD consistently displayed a reduced performance versus its DGFEM-0 results in terms of accuracy and precision metrics, though it was not typically grossly inaccurate. This is attributed to the irregularities in the true solution across singular characteristics limiting the local accuracy of the numerical flux solution, leading to poor derivative approximations used in the residual approximations. The error transport problem then spreads the error in the residual to nearby cells, causing a greater degree of imprecision that did not afflict DAZ or RW. In testing the estimators on realistic problem geometries, however, LeR/TE-AD fared better. In practice, the true error is much larger in non-idealized geometries like in MMS, and a superlinear true solution means that RW and DAZ are not beneficially biased for DGFEM-1 error estimation. LeR/TE-AD was typically first or second in accuracy, primarily competing with RW, but the latter usually consumed 2-4 times the computational time as LeR/TE-AD, and requires a solution with four times as many unknowns. Furthermore, RW and LeR/TE-AD can be used to compute direct estimates of the error in any quantity of interest that is based on the angular ux solution, such as the fission rate density in a fuel pin, whereas DAZ requires a heuristic extension due to its norm-based nature.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Analysis on Part Distortion and Residual Stress in Big Area Additive Manufacturing with Carbon Fiber-Reinforced Thermoplastic using Dehomogenization Technique

Part distortion and bottom surface warpage often occur in extrusion-based additive manufacturing. The undesirable deformations during the printing process are due to residual stresses caused by material shrinkage. Analysis on residual stress and deformation requires accurate thermo-mechanical material properties. Polymer composites reinforced with short fibers have intrinsic inhomogeneities with nonuniform fiber orientation. Therefore, homogenized macro properties may not accurately represent the progressive damage behavior or distortion. In this study, fiber orientations in Acrylonitrile Butadiene Styrene (ABS) reinforced with 20%wt carbon fiber are calculated using a de-homogenization technique. Thermal expansion coefficients in multiple directions are obtained from Thermo-Mechanical Analysis (TMA) tests. Temperature dependent stiffness is measured, and temperature dependent strength is estimated. Thermal conductivities in multiple directions and thermal capacity are measured. The calibrated thermo-mechanical properties of the composite with de-homogenized technique are used to analyze the residual stress and distortion of a 4 ft-wide wall printed in the Big Area Additive Manufacturing (BAAM) system. For experimental measurement on the wall printing, Infra-Red (IR) camera captures the temperature field, and Linear Variable Differential Transformer (LVDT) is installed to measure the warpage at the bottom surface. The experimental data are compared to the numerical analysis results. The temperature profile and the distortion profile from experiment are close to the simulation results. Damages due to residual stress and distortion are analyzed.

Kim, Pum↗
DOE OSTI2019

Sky Residual Correction

The near-infrared is populated by numerous emission lines radiated from the Earth’s atmosphere, and these emission lines are often several orders of magnitude brighter in intensity than the typical astrophysical science target. The subtraction of these emission lines, sky subtraction, can create large systematic errors in ground-based astronomical spectra effectively limiting the number of usable resolution elements. A more effective sky subtraction, and the reduction of the systematic errors due to the sky subtraction process, is a major hurdle which ground-based astronomy must overcome to increase the amount of usable spectrum, and to be able to observe fainter scientific targets. Large high-quality data sets such as the Sloan Digital Sky Survey (SDSS) in themselves present opportunities for a reduction of the systematic sky subtraction errors through self-calibration. The sky residual correction method of Wild and Hewett is one such self-calibration technique which uses principal component analysis to reduce the systematic sky residual errors present in SDSS spectra. We apply sky residual corrections to the SDSS, Baryon Oscillation Spectroscopic Survey, and Apache Point Observatory Galactic Evolution Experiment data sets to optimize the number of subtraction components, and to quantify the reduction of the systematic errors in the science spectra. Finally as a proof of concept we use the sky-residual-corrected SDSS luminous red galaxy spectra to search for gravitationally lensed emission line Galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Data from: Hotspots of soil N2O emission enhanced through water absorption by plant residue

N2O is a highly potent greenhouse gas and arable soils represent its major anthropogenic source. Field-scale assessments and predictions of soil N2O emission remain uncertain and imprecise due to the episodic and microscale nature of microbial N2O production, most of which occurs within very small discrete soil volumes. Such hotspots of N2O production are often associated with decomposing plant residue. Here we quantify physical and hydrological soil characteristics that lead to strikingly accelerated N2O emissions in plant residue-induced hotspots. Results reveal a mechanism for microscale N2O emissions: water absorption by plant residue that creates unique micro-environmental conditions, markedly different from those of the bulk soil. Moisture levels within plant residue exceeded those of bulk soil by 4–10-fold and led to accelerated N2O production via microbial denitrification. The presence of large (∅ >35 μm) pores was a prerequisite for maximized hotspot N2O production and for subsequent diffusion to the atmosphere. Understanding and modelling hotspot microscale physical and hydrologic characteristics is a promising route to predict N2O emissions and thus to develop effective mitigation strategies and estimate global fluxes in a changing environment.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1975

Lamination residual stresses in fiber composites

An experimental investigation was conducted to determine the magnitude of lamination residual stresses in angle-ply composites and to evaluate their effects on composite structural integrity. The materials investigated were boron/epoxy, boron/polyimide, graphite/low modulus epoxy, graphite/high modulus epoxy, graphite/polyimide and s-glass/epoxy. These materials were fully characterized. Static properties of laminates were also determined. Experimental techniques using embedded strain gages were developed and used to measure residual strains during curing. The extent of relaxation of lamination residual stresses was investigated. It was concluded that the degree of such relaxation is low. The behavior of angle-ply laminates subjected to thermal cycling, tensile load cycling, and combined thermal cycling with tensile load was investigated. In most cases these cycling programs did not have any measurable influence on residual strength and stiffness of the laminates. In the tensile load cycling tests, the graphite/polyimide shows the highest endurance with 10 million cycle runouts at loads up to 90 percent of the static strength.

Daniel, I. M.↗
NASA NTRS1976

Longitudinal residual stresses in boron fibers

A technique is proposed for measuring the longitudinal residual stress distribution in commercial CVD (Chemical Vapor Deposition) boron on tungsten fibers of 102, 142, and 203 microns in diameter. The experimental apparatus is so designed that continuous measurements are made of the length changes of a boron fiber specimen as the surface of the fiber is removed by electropolishing. The effects of surface removal on core residual stress and core-initiated fracture are discussed. The three sizes of boron fibers investigated show similar residual stress distributions, i.e., compressive at the surface, tensile near the core, and for the 102-micron fiber compressive again in the core. It is shown that an increase in UTS is due to the increase in the compressive stress at the core produced by fiber contraction during surface removal. An expression is derived for calculating the longitudinal residual stress at a given radius for an as-received fiber of a certain radius from measurements of the axial strain produced by removal of the surface by electropolishing.

Behrendt, D. R.↗