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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,513 records · Page 84
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Magnetoelectric memory cells with domain-wall-mediated switching

A magnetoelectric memory cell with domain-wall-mediated switching is implemented using a split gate architecture. The split gate architecture allows a domain wall to be trapped within a magnetoelectric antiferromagnetic (MEAF) active layer. An extension of this architecture applies to multiple-gate linear arrays that can offer advantages in memory density, programmability, and logic functionality. Applying a small anisotropic in-plane shear strain to the MEAF can block domain wall precession to improve reliability and speed of switching.

42 ENGINEERING↗
DOE OSTI2020

Radial Wall Jet Flow Over Sigmoidal Surfaces

Radial wall jet flows across flat smooth surfaces have been studied for decades. These studies show that the radial velocity of these jets decays inversely with distance from the nozzle with modest contribution from friction (Poreh, et al., 1967; Rajaratnam, 1976). However, the extent to which flat surface results apply to curved surfaces remains unclear. In this article we explore the influence of settled particle bed slope on these velocity profiles. We model the step change in thickness as a sigmoidal curve of variable steepness and use conservation of momentum to evaluate the velocity profile. We show that the velocity profile attenuates because of curvature. Next, we evaluate the influence of surface curvature on radial wall jet flow. Jet flows over particle beds often introduce curvature in the particle bed profile but the influence of the developed curvature on the velocity profile has not been explored. Here we develop a solution for steady fixed beds based on conservation of momentum. We find that surface curvature has a significant influence on the velocity decay coefficients and celerity of radial wall jets, provided there is velocity slip in the vicinity of the particle bed interface, which is strictly true for particle surfaces. Conservation of momentum predicts conditions where the forward momentum of the flow is directed completely upward. The solution identifies two new dimensionless groups that determine whether a curved surface is sufficient to block radial flow and force flow vertically.

Surface curvature, jet flow, multiphase flow↗
DOE OSTI2022

Ultrasonic through-wall sensors

Aspects of ultrasonic through-wall data communication are described. In some aspects, a sensor device is located in an isolated environment behind a wall. A modulator generates a modulated sensor signal based on the binary sensor signal and a carrier signal. A coaxially aligned pair of electroacoustic transducers that transmits the modulated sensor signal through the wall of the isolated environment. A demodulator demodulates the modulated sensor signal to generate a demodulated binary sensor signal. A sensor data recovery component converts the demodulated binary sensor signal into an image or another sensor parameter.

Zhang, Haifeng↗
DOE OSTI2023

Methods for controlling cell wall biosynthesis and genetically modified plants

The present disclosure provides methods of producing plants with preferred levels of cell wall biosynthesis; and uses of such plants. The inventors have identified that the GFR9, CCoAOMT and MYB41 genes are major regulators of the cell wall biosynthesis pathway. Plants with modulated cell wall biosynthesis, based on modulation of the expression or activity of the GFR9, CCoAOMT and MYB41 genes, have divergent uses including pulp and paper production, and bioproduct production.

Tschaplinski, Timothy J.↗
DOE OSTI2016

The Effectiveness of Gd Contents of Fuel Basket Wall in UNF Shipping and Storage Cask - 16598

A more effective basket structure, which employs the single wall basket structure and more effective neutron absorbing materials compared to the conventional 3 wall structure with boron neutron absorber, is under development. The criticality of the cask was evaluated as a function of the Gd and B contents in the plate and the Gd-containing SS plate thickness while maintaining the basic geometry the same as the reference cask which uses boron compound as neutron absorber. The KENO-VI code in SCALE with the data library ENDF/B-VII 238-group was used. In all the range of interest, the k{sub eff} values are below 0.4 which is much lower than licensing limit of 0.95. As Gd content increases, the k{sub eff} exponentially decreases. The Gd added SS shows higher performance than B added case in low atomic percent region. The B case curve showed less steep slope than the Gd case. The results of the wall thickness effect calculation indicated that the k{sub eff} decreases with thickness increase until ∼6 mm and it increases as thickness increases over ∼7 mm. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Resolution requirements for high-speed droplet impact along a rigid wall

The mechanical and thermal loads that are produced on high-speed projectiles from a droplet are key in the projectile development.To accurately predict the pressure produced along the wall surface during impact, it is important to correctly model the air/water interface of the droplet. Novel modeling approaches such as the Phase-Field enable control of the (numerical) interface thickness. However, the interplay between the grid resolution (including potential adaptive mesh refinement) and the interface thickness is unclear. In this work, the resolution requirements for numerical simulations of a two-dimensional cylindrical water droplet impacting a rigid wall at Mach four are computationally investigated. Numerical simulations are performed using a second-order accurate scheme with adaptive mesh refinement and a Phase-Field interface model. The choice of numerical interface thickness and resolution parameters affects the maximum pressure and location of the maximum pressure along the wall. The overall maximum pressure does not converge even at high resolutions. The number of levels and thickness (number of cells across the interface) play a role in obtaining a well behaved solution.

Burrell, E.↗
DOE OSTI2019

Fusion applications for lithium: wall conditioning in magnetic confinement devices

The application of lithium to plasma facing components (PFCs) has been widely used to improve plasma performance in magnetic confinement devices. The ability of lithium to retain hydrogen isotopes has been exploited to lower wall recycling. Low recycling leads to high edge plasma temperatures, and decreased temperature gradients reduce the free energy source for microinstabilities that cause transport. A variety of techniques have been developed to introduce lithium into fusion research devices, and its beneficial effects have been observed in their plasmas. The mechanism for the retention of hydrogen isotopes has been elucidated by detailed surface science studies, and 'first principles' molecular dynamics simulations. The remaining challenges primarily pertain to long pulse operation. Our knowledge of erosion, transport, and redeposition needs to improve for the mixed material PFCs lithium creates. As a result, flowing liquid lithium systems also must be demonstrated for the replenishable lithium walls that fusion reactors require.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Evolution of p -coumaroylated lignin in eudicots provides new tools for cell wall engineering

Ester-linked p-coumarate (pCA) is a hallmark feature of the secondary cell walls in commelinid monocot plants. It has been shown that pCA groups arise during lignin polymerisation from the participation of monolignol conjugates assembled by p-coumaroyl-CoA:monolignol transferase (PMT) enzymes, members of the BAHD superfamily of acyltransferases. Herein we report that a eudicot species, kenaf (Hibiscus cannabinus), naturally contains p-coumaroylated lignin in the core tissues of the stems but not in the bast fibres. Moreover, we identified a novel acyltransferase, HcPMT, that shares less than 30% amino acid identity with known monocot PMT sequences. Recombinant HcPMT showed a preference in enzyme assays for p-coumaroyl-CoA and benzoyl-CoA as acyl donor substrates, and sinapyl alcohol as an acyl acceptor. Heterologous expression of HcPMT in hybrid poplar trees led to the incorporation of pCA in lignin but no improvement in the saccharification potential of the wood. This work illustrates the value in mining diverse plant taxa for new monolignol acyltransferases. Furthermore, the occurrence of pCA outside of monocot lineages may represent another example of convergent evolution in lignin structure. Furthermore, this discovery expands textbook views on cell wall biochemistry and provides a new molecular tool for engineering the lignin of biomass feedstock plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Machining of Thin-Walled Structures From Stiffness-Driven Additively Manufactured Preform Geometry

Additive manufacturing provides the means to build component preforms with reduced excess material to create functional parts. In the case of aero-structural and aero-engine components, additive manufacturing technologies offer the possibility to substantially reduce the volume of material to be removed by machining operations. To achieve this objective, the preform must be built with the minimum material necessary to contain the final geometry and simultaneously provide enough stiffness to withstand the magnitude of the machining forces. This work describes a computationally efficient method to calculate the geometry required from the preform to reliably manufacture typical thin-walled structures via finish machining processes. This is achieved by defining the preform with near constant static stiffness across the width of the preform, in combination with a prescribed magnitude of stiffness at the top edge of the preform. The prescribed static stiffness is the function of the machining force magnitude, a direct consequence of the preselected cutting conditions. In conclusion, this article illustrates the application of the method to a straight single boundary thin-walled structure as an introduction case and for ease of description.

Additive manufacturing↗
DOE OSTI2016

Using Retrofit Nail Base Panels to Expand the Market for Wall Upgrades

This project evaluated the effectiveness and affordability of integrating retrofit insulated panels into a re-siding project. The Partnership for Home Innovation (PHI) teamed with New York State Energy Research and Development Authority (NYSERDA), the Albany Housing Authority (AHA), and the New York State Weatherization Assistance Program (WAP) administered by Albany Community Action Partnership to demonstrate an energy retrofit and siding upgrade on a two-story, seven unit, multifamily building in Albany New York (CZ 5). The project focused on accomplishing three goals - doubling the existing wall thermal resistance (from approximately R-13 to a weighted average of R-27), reduction of building air leakage, and completion of the retrofit within a budget where the additional cost for upgrading wall's thermal resistance is equal to the cost of the standard re-siding effort (i.e., the total cost of the energy efficient re-siding scope of work is not more than double the cost of the standard re-siding effort). Lessons learned from the project strongly indicate that the retrofit panel technology can be installed using common installation practices and with minimal training. Other lessons learned include limitation on the use of standard air sealing materials during cold weather installations and the need to develop better installation guidance for trades working with the level of tolerances that may be present in the existing structure. This technology demonstration showed that exterior retrofit panels provide a viable and reasonable option for the siding trades to increase market opportunities and achieve synergistic benefits for aesthetic upgrades to a building's exterior.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Extended Plate and Beam Wall System

Home Innovation Research Labs studied the extended plate and beam wall (EP&B) system during a two-year period from mid-2015 to mid-2017 to determine the wall’s structural performance, moisture durability, constructability, and cost effectiveness for use as a high-R enclosure system for energy code minimum and above-code performance in climate zones 4–8.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

A computational study of turbulent separated flow over a wall-mounted cube at two different Reynolds numbers and incoming velocity profiles

Simulations of the canonical wall-mounted unit cube subjected to two distinct incident velocity profiles is performed at Reynolds numbers (Re) where the bulk flow characteristics are known to become relatively Re-insensitive using both direct numerical simulation (DNS) and wall-resolved large eddy simulation (WRLES). The aim of this work is to highlight the sensitivity of such bluff-body flows to mean shear and to provide a representative set of data for such flow scenarios where common turbulence modeling techniques often fail. Simple boundary conditions are selected to allow for easy comparisons for model development purposes and avoid confounding effects from freestream turbulence. In addition to mean velocity profiles, select turbulence statistics are presented in detail. We find that both mean velocity profiles and mean wake turbulence are Re-insensitive over the range examined here.

42 ENGINEERING↗
DOE OSTI2021

Xylan Is Critical for Proper Bundling and Alignment of Cellulose Microfibrils in Plant Secondary Cell Walls

Plant biomass represents an abundant and increasingly important natural resource and it mainly consists of a number of cell types that have undergone extensive secondary cell wall (SCW) formation. These cell types are abundant in the stems of Arabidopsis, a well-studied model system for hardwood, the wood of eudicot plants. The main constituents of hardwood include cellulose, lignin, and xylan, the latter in the form of glucuronoxylan (GX). The binding of GX to cellulose in the eudicot SCW represents one of the best-understood molecular interactions within plant cell walls. The evenly spaced acetylation and 4-O-methyl glucuronic acid (MeGlcA) substitutions of the xylan polymer backbone facilitates binding in a linear two-fold screw conformation to the hydrophilic side of cellulose and signifies a high level of molecular specificity. However, the wider implications of GX–cellulose interactions for cellulose network formation and SCW architecture have remained less explored. In this study, we seek to expand our knowledge on this by characterizing the cellulose microfibril organization in three well-characterized GX mutants. The selected mutants display a range of GX deficiency from mild to severe, with findings indicating even the weakest mutant having significant perturbations of the cellulose network, as visualized by both scanning electron microscopy (SEM) and atomic force microscopy (AFM). We show by image analysis that microfibril width is increased by as much as three times in the severe mutants compared to the wild type and that the degree of directional dispersion of the fibrils is approximately doubled in all the three mutants. Further, we find that these changes correlate with both altered nanomechanical properties of the SCW, as observed by AFM, and with increases in enzymatic hydrolysis. Results from this study indicate the critical role that normal GX composition has on cellulose bundle formation and cellulose organization as a whole within the SCWs.

09 BIOMASS FUELS↗
DOE OSTI2025

Crossing the Oxo‐Peroxo Wall for Selective Electrochemical Epoxidation

Electrochemical oxidation in water requires the formation of reactive oxygen species to be able to oxidize unsaturated hydrocarbons to epoxides, aldehydes, and ketones. These reactions, broadly classified as alternative oxidation reactions (AOR), directly compete with the prevalent oxygen evolution reaction (OER). In molecular catalysis, the Oxo-Wall dictates a transition from a stable oxo intermediate (OER active) to a meta-stable metal-oxo (OER inactive) generally occurs. In this work on heterogeneous catalysis, the same Oxo-Wall applies, however, a meta-stable oxo preferentially coordinates with lattice oxygen to form a more stable surface peroxo intermediate. A universal free energy onset of this process is identified at 3.39 eV under electrochemical activation in water and show that it is completely decoupled from the OER oxo species. Such decoupling gives rise to a new region of oxygen reactivity relevant for AOR where a selective oxidation of the unsaturated C-C bonds is predicted to occur instead of OER. A distinct AOR overpotential volcano is constructed and identify recently reported electrocatalysts, including palladium-platinum for propylene epoxidation and silver-nickel for ethylene epoxidation, along with others such as TiO 2 and CuO. Broader implications and limitations of electrochemical AOR are discussed, highlighting their potential to enable electrochemically enhanced thermal catalysis.

Electrocatalysis↗
DOE OSTI2018

Theoretical Studies on Magnetic Structures, Hysteresis Loops and Size Effects of a Pair of Frustrated Double-Walled Nanotubes

We propose a theoretical quantum model and derive a set of analytic formulas to study the physical properties of a pair of double-walled magnetic nanotubes. The Heisenberg exchange parameters between the two walls of the nanotubes are assumed to differ only in sign. Thus, in the absence of external magnetic field, our calculated macroscopic properties of this pair of nanotubes are almost precisely identical, exhibiting fascinating duality of the nanosystems and demonstrating the correctness of our theoretical model. The two spin systems are all frustrated, so that sudden changes in the macroscopic properties are observed around T{sub M2} that is well below the transition temperature T{sub M1}. However, only the inner shell consisting of smaller A-type spins has been obviously affected. In the temperature range T{sub M2} < T < T{sub M1}, this shell becomes semi-antiferromagnetic and its magnetization is considerably suppressed, whereas as temperature falls below T{sub M2} the shell gradually restores its ferromagnetic nature. The longitudinal hysteresis behavior of such a double-waled nanotube is ferromagnetic-like below T{sub M2}, but antiferromagnetic-like in the temperature interval T{sub M2} < T < T{sub M1}. Moreover, we find that the diameter of the nanotube has seemly no effects on its physical properties, whereas its length does affects the two temperatures slightly, and also its spin configuration at very low temperatures if the tube is sufficiently long. More importantly, the theoretical results presented in this paper can be precisely reproduced with the quantum computational method we develop in recent years, justifying the validity of the numerical approach once again.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up to 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Metabolites of 2,3-diketogulonate delay peroxidase action and induce non-enzymic H 2 O 2 generation: Potential roles in the plant cell wall

A proportion of the plant's l-ascorbate (vitamin C) occurs in the apoplast, where it and its metabolites may act as pro-oxidants and anti-oxidants. One ascorbate metabolite is 2,3-diketogulonate (DKG), preparations of which can non-enzymically generate H 2 O 2 and delay peroxidase action on aromatic substrates. As DKG itself generates several by-products, we characterised these and their ability to generate H 2 O 2 and delay peroxidase action. DKG preparations rapidly produced a by-product, compound ( 1 ), with λ max 271 and 251 nm at neutral and acidic pH respectively. On HPLC, ( 1 ) co-eluted with the major H 2 O 2 -generating and peroxidase-delaying principle. Compound ( 1 ) was slowly destroyed by ascorbate oxidase, and was less stable at pH 6 than at pH 1. Electrophoresis of an HPLC-enriched preparation of ( 1 ) suggested a strongly acidic (p K a ≈ 2.3) compound. Mass spectrometry suggested that un-ionised ( 1 ) has the formula C 6 H 6 O 5 , i.e. it is a reduction product of DKG (C 6 H 8 O 7 ). In conclusion, compound ( 1 ) is the major H 2 O 2 -generating, peroxidase-delaying principle formed non-enzymically from DKG in the pathway ascorbate → dehydroascorbic acid → DKG → ( 1 ). We hypothesise that ( 1 ) generates apoplastic H 2 O 2 (and consequently hydroxyl radicals) and delays cell-wall crosslinking - both these effects favouring wall loosening, and possibly playing a role in pathogen defence.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

A study of solid wall models for weakly compressible SPH

This paper is concerned with a comparison of two methods of treating solid wall boundaries in the weakly compressible (SPH) method. They have been chosen because of their wide use in simulations. These methods are the boundary force particles of Monaghan and Kajtar [24] and the use of layers of fixed boundary particles. The latter was first introduced by Morris et al. [26] but has since been improved by Adami et al. [1] whose algorithm involves interpolating the pressure and velocity from the actual fluid to the boundary particles. For each method, we study the effect of the density diffusive terms proposed by Molteni and Colagrossi [19] and modified by Antuono et al. [3]. We test the methods by a series of simulations commencing with the time-dependent spin-down of fluid within a cylinder and the behaviour of fluid in a box subjected to constant acceleration at an angle to the walls of the box, and concluding with a dam break over a triangular obstacle. In the first two cases the results from the two methods can be compared to analytical solutions while, in the latter case, they can be compared with experiments and other methods. These results show that the method of Adami et al. together with density diffusion is in very satisfactory agreement with the experimental results and is, overall, the best of the methods discussed here.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗