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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Low-Speed Performance Enhancement Using Localized Active Flow Control: Localized Active Flow Control Simulations on a Reference Aircraft (2/4)

A study of the potential implementations of localized active flow control (AFC) technology onto future airplanes is presented. This collaborative investigation addresses key objectives of the NASA Advanced Air Transport Technology (AATT) Project, in terms of reduction in fuel consumption and lower emission. It specifically targets the goals set forth in a roadmap developed by the NASA/Boeing team. The roadmap is a result of a series of meetings held between the two parties over the years and it represents a shared vision for practical implementations, leading up to flight demonstrations of localized flow control. If successful, localized flow control may lead to important ramifications for next generation airplanes from both the economic and environmental perspectives. Under this contract localized AFC has been used to improve aerodynamic performance during high-lift operations using Computational Fluid Dynamics (CFD). Specifically, AFC has been applied at the aileron and at various location in the wing leading edge (LE) regions. The applications target reduced drag and enhanced lift over the range of practical angles of attack, including stall. These benefits translate to airplane performance improvements, such as longer range or larger payload. The CFD results are used to quantify potential aerodynamic benefits, as well as the input required for actuation. This helps identify the most promising candidates, which potentially provide material net airplane level enhancements using onboard fluidic sources. The airplane configuration selected for the CFD study is a representative of a future short/medium-range twin-engine airplane dubbed the Reference Aircraft. A slew of AFC applications has been explored and their aerodynamic performance enhancements were benchmarked against the baseline Reference Aircraft. Promising AFC candidates have been deemed practical and potentially suitable for both the aileron and the wing LE implementations. The findings on the Reference Aircraft are used to guide the development of the AFC-enhanced aileron for the CRM-HL. The wind-tunnel model of the CRM-HL will be used by NASA to validate the AFC concepts, complementing the CFD-based analysis and the integration study (final report document #3).

CFD↗
DOE OSTI2014

Place Based STEM: Leveraging Local Resources to Engage K-12 Teachers in Teaching Integrated STEM and for Addressing the Local STEM Pipeline

Business, industry, parks, nature settings, government infrastructure, and people, can be invaluable resources for connecting STEM curriculum within context which results in conditions ideal for promoting purposeful learning of authentic STEM content. Thus, community-based STEM resources offer ideal context for teaching STEM content. A benefit of focusing teacher attention on these contextual, content aligned resources is that they are in every community; making place-based STEM education a possibility, regardless of the location of STEM teaching and learning. Further, associating STEM teaching and learning with local resources addresses workforce development and the STEM pipeline by exposing students to STEM careers and applications in their local communities. The desire to align STEM teaching and learning with local STEM related resources guided the design of our week-long integrated STEM K-12 teacher professional development (PD) program, i-STEM. We have completed four years of our i-STEM PD program and have made place-based STEM a major emphasis of our curriculum. This report focuses on the data collected in the fourth year of our program. Our week-long i-STEM PD served over 425 educators last summer (2013), providing them with in depth theme-based integrated STEM short courses which were limited to an average of 15 participants and whole group plenary sessions focused around placed based integrated STEM, inquiry, engineering design, standards and practices of Common Core and 21st Century skills. This state wide PD was distributed in five Idaho community colleges and took place over two weeks. The STEM short courses included topics on engineering for sustainability, using engineering to spark interest in STEM, municipal water systems, health, agriculture, food safety, mining, forestry, energy, and others. Integral to these short courses were field trips designed to connect the K-12 educators to the resources in their local communities that could be leveraged for teaching integrated STEM and provide a relevant context for teaching STEM content. Workplace presentations made by place-based STEM experts and provided teachers field trips to place-base STEM industries and business such as manufacturing plants, waste water treatment systems, mines, nature parks, food processing plants, research, hospitals, and laboratory facilities. We researched the 425 participants’ conceptions of place-based STEM prior to and after their taking part in the summer institutes, which included fieldtrips. Our findings revealed substantial increase in our participants’ knowledge, interest, and plans to use place-based resources for teaching integrated STEM. We detail the data analysis and provide a theoretical foundation and justification for the importance of place-based STEM to address the STEM pipeline for the future workforce.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Localization of a radioactive source in an urban environment using Bayesian Metropolis methods [Bayesian Metropolis methods for source localization in an urban environment]

Here, we present a method for localizing an unknown source of radiation in an urban environment using a distributed detector network. This method employs statistical parameter estimation techniques, relying on an approximation for the response of a detector to the source based on a simplified model of the underlying transport phenomena, combined with a Metropolis-type sampler that is modified to propagate the effect of fixed epistemic uncertainties in the material macroscopic cross sections of objects in the scene. We apply this technique to data collected during a measurement campaign conducted in a realistic analog for an urban scene using a network of six mobile detectors. Our initial results are able to localize the source to within approximately 8 m over a scene of size 300 m 200 m in two independent trials with 30 min count times, including a characterization of the uncertainty associated with the poorly known macroscopic cross sections of objects in the scene. In these measurements, the nearest detectors were between 20 m to 30 m from the source, and recorded count rates between approximately 3 and 13 times background. A few detectors had line-of-sight to the source, while the majority were obscured by objects present in the scene. After extending our model to account for the orientation of the detectors and correcting for anomalies in the measurement data we were able to further improve the localization accuracy to approximately 2 m in both trials.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Measuring Local Electric Fields and Local Charge Densities at Electrode Surfaces Using Graphene-Enhanced Raman Spectroscopy (GERS)-Based Stark-Shifts

Here, we report spectroscopic measurements of the local electric fields and local charge densities at electrode surfaces using graphene-enhanced Raman spectroscopy (GERS) based on the Stark-shifts of surface-bound molecules and the G band frequency shift in graphene. Here, monolayer graphene is used as the working electrode in a three-terminal potentiostat while Raman spectra are collected in situ under applied electrochemical potentials using a water immersion lens. First, a thin layer (1 Å) of copper(II) phthalocyanine (CuPc) molecules are deposited on monolayer graphene by thermal evaporation. GERS spectra are then taken in an aqueous solution as a function of the applied electrochemical potential. The shifts in vibrational frequencies of the graphene G band and CuPc are obtained simultaneously and correlated. The upshifts in the G band Raman mode are used to determine the free carrier density in the graphene sheet under these applied potentials. Of the three dominant peaks in the Raman spectra of CuPc (i.e., 1531, 1450, and 1340 cm –1 ), only the 1531 cm –1 peak exhibits Stark-shifts and can, thus, be used to report the local electric field strength at the electrode surface under electrochemical working conditions. Between applied electrochemical potentials from -0.8 V to 0.8 V vs NHE, the free carrier density in the graphene electrode spans a range from -4 × 10 12 cm –2 to 2 × 10 12 cm –2 . Corresponding Stark-shifts in the CuPc peak around 1531 cm –1 are observed up to 1.0 cm –1 over a range of electric field strengths between -3.78 × 10 6 and 1.85 × 10 6 V/cm. Slightly larger Stark-shifts are observed in a 1 M KCl solution, compared to those observed in DI water, as expected based on the higher ion concentration of the electrolyte. Based on our data, we determine the Stark shift tuning rate to be 0.178 cm –1 / (10 6 V/cm), which is relatively small due to the planar nature of the CuPc molecule, which largely lies perpendicular to the electric field at this electrode surface. Computational simulations using density functional theory (DFT) predict similar Stark shifts and provide a detailed atomistic picture of the electric field-induced perturbations to the surface-bound CuPc molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

On the mass of the local group

We use recent proper motion measurements of the tangential velocity of M31, along with its radial velocity and distance, to derive the likelihood of the sum of halo masses of the Milky Way and M31. This is done using a sample of halo pairs in the Bolshoi cosmological simulation of ΛCDM cosmology selected to match the properties and the environment of the Local Group. The resulting likelihood gives an estimate of the sum of the masses of M {sub MW,} {sub 200c} + M {sub M31,} {sub 200c} = 2.40{sub −1.05}{sup +1.95}×10{sup 12} M{sub ⊙} (90% confidence interval). This estimate is consistent with individual mass estimates for the Milky Way and M31 and is consistent, albeit somewhat on the low side, with the mass estimated using the timing argument. We show that although the timing argument is unbiased on average for all pairs, for pairs constrained to have radial and tangential velocities similar to that of the Local Group the argument overestimates the sum of masses by a factor of 1.6. Using similar technique, we estimate the total dark matter mass enclosed within 1 Mpc from the Local Group barycenter to be M{sub LG}(r<1 Mpc)=4.2{sub −2.0}{sup +3.4}×10{sup 12} M{sub ⊙} (90% confidence interval).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

A meshless Galerkin method for non-local diffusion using localized kernel bases

Here, we introduce a meshless method for solving both continuous and discrete variational formulations of a volume constrained, nonlocal diffusion problem. We use the discrete solution to approximate the continuous solution. Our method is nonconforming and uses a localized Lagrange basis that is constructed out of radial basis functions. By verifying that certain inf-sup conditions hold, we demonstrate that both the continuous and discrete problems are well-posed, and also present numerical and theoretical results for the convergence behavior of the method. The stiffness matrix is assembled by a special quadrature routine unique to the localized basis. Combining the quadrature method with the localized basis produces a well-conditioned, symmetric matrix. This then is used to find the discretized solution.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Concavity-based local erosion and sphere-size-based local dilation applied to lithium-ion battery electrode microstructures for particle identification

Performance metrics of lithium-ion batteries can be extracted from the analysis of electrode microstructures nanoscale imaging. The characterization workflow can involve a challenging particle identification, or instance segmentation, step. In this work, we propose a new identification method based on an original transformation: a sphere-size-based local dilation followed by a concavity-based local erosion, that is local morphology closing. The new transformation is much more efficient than the global morphology closing, with correct identification achieved with only 1.7 % dilation volume and 2.6 % erosion volume on a test geometry, compared to 39.2 % and more than 50 %, respectively, with its global counterpart. The new method has been then benchmarked versus other identification algorithms (watershed and pseudo coulomb repulsive field) on a real electrode microstructure with equal or better segmentation achieved.

25 ENERGY STORAGE↗
DOE OSTI2021

Intraoperative Electron Beam Radiation Therapy (IOERT) Versus High-Dose-Rate Intraoperative Brachytherapy (HDR-IORT) in Patients With an R1 Resection for Locally Advanced or Locally Recurrent Rectal Cancer

Intraoperative radiation therapy (IORT), delivered by intraoperative electron beam radiation therapy (IOERT) or high-dose-rate intraoperative brachytherapy (HDR-IORT), may reduce the local recurrence rate in patients with locally advanced and locally recurrent rectal cancer (LARC and LRRC, respectively). The aim of this study was to compare the oncological outcomes between both IORT modalities in patients with LARC or LRRC who underwent a microscopic irradical (R1) resection.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Dynamic shear localization of a titanium alloy under high-rate tension characterized by x-ray digital image correlation

Highlights: • First systematic error analyses for XDIC • First XDIC study of Ti-6Al-4V under dynamic tension • Deformation mode transition induces dynamic ductility decrease. • Dynamic shear localization due to rate-dependent microvoid coalescence process. - Abstract: Dynamic and quasi-static tension experiments are conducted on Ti-6Al-4V alloys, with in situ, synchrotron-based, high-speed, x-ray phase contrast imaging implemented to characterize the dynamic deformation and fracture process of Ti alloys at the Advanced Photon Source. X-ray digital imaging correlation (XDIC) is applied for strain field mapping. The size distribution of x-ray speckles are quantified via a morphological analysis, with a mean of ∼20 μm. Systematic error analyses of displacement and strain field measurements are firstly conducted for XDIC, and demonstrate that the displacement and strain errors can be controlled below 0.01 pixel and 0.1%, respectively. Mesoscale strain characteristics measured via XDIC are consistent with and reveal mechanisms for the bulk-scale stress–strain responses. Under dynamic tension, a sharp transition to strain softening occurs when the bulk strain exceeds about 0.04, which leads to a lower dynamic fracture strain (0.08) than the quasi-static one (0.1). The corresponding strain filed mapping demonstrates that shear deformation localizations grow and coalesce rapidly into a narrow shear deformation band under dynamic loading, while tensile deformation and necking progresses gradually under quasi-static loading. Scanning electron microscopy shows that void nucleation occurs mainly at the interface of α and β phases for both quasi-static and dynamic tension. However, microvoids coalesce preferentially along colony boundaries or the boundary α phase under quasi-static tension, but along the maximum shear stress direction (across colonies) under dynamic tension. Fractography of recovered samples also shows consistent features.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Local Lattice Distortions in Mn[N(CN) 2 ] 2 under Pressure

We combined synchrotron-based infrared spectroscopy, Raman scattering, and diamond anvil cell techniques with complementary lattice dynamics calculations to reveal local lattice distortions in Mn[N(CN)2]2 under compression. Strikingly, we find a series of transitions involving octahedral counter-rotations, changes in the local Mn environment, and deformations of the superexchange pathway. In addition to reinforcing trends in the magnetic exchange anisotropy, these pressure-induced local lattice distortions may provide an avenue for the development of new functionalities.

Brinzari, Tatiana V.↗
DOE OSTI2026

Local Spin Density Approximation Strongly Improved by a Better-Informed Local Scaling of Its Self-Interaction Correction

The Perdew−Zunger self-interaction correction (PZSIC) makes density functional approximations (DFAs) exact for all one-electron densities. However, it overcorrects in manyelectron regions, introducing errors for the uniform-density limit, where uncorrected DFAs are exact. The locally scaled PZSIC (LSIC), based on the iso-orbital indicator zσ [which distinguishes single-orbital and slowly varying density regions and is used with the local spin density approximation (LSDA)], restores the uniform-density limit and significantly improves results for many properties, including chemical reaction barrier heights, atomization energies, and ionization potentials. Yet, LSIC performs poorly for weakly bonded systems, leaving many unbound, due to limitations of its iso-orbital indicator. To correct this, in this work we propose a new local scaling, LSIC-α, based on the iso-orbital indicator ασ (which additionally identifies regions of overlapping density tails). A two-parameter scaling function of ασ is fitted to a subset of the nonbonded appropriate norms for the SCAN and r2SCAN meta- GGAs, and tested on many properties of main-group atoms, molecules, and molecular complexes. LSIC-α greatly improves the interaction energies of weakly bonded systems in the S22 data set while retaining LSIC’s accuracy for other properties. This work shows that the errors of LSDA (and presumably of higher-level DFAs) can be largely but not entirely repaired by a proper “do no harm” self-interaction correction.

Approximation↗
DOE OSTI2023

Localized high-concentration electrolytes get more localized through micelle-like structures

Liquid electrolytes in batteries are typically treated as macroscopically homogeneous ionic transport media despite having a complex chemical composition and atomistic solvation structures, leaving a knowledge gap of the microstructural characteristics. Here, we reveal a unique micelle-like structure in a localized high-concentration electrolyte, in which the solvent acts as a surfactant between an insoluble salt in a diluent. The miscibility of the solvent with the diluent and simultaneous solubility of the salt results in a micelle-like structure with a smeared interface and an increased salt concentration at the centre of the salt–solvent clusters that extends the salt solubility. These intermingling miscibility effects have temperature dependencies, wherein a typical localized high-concentration electrolyte peaks in localized cluster salt concentration near room temperature and is used to form a stable solid–electrolyte interphase on a Li metal anode. Importantly, these findings serve as a guide to predicting a stable ternary phase diagram and connecting the electrolyte microstructure with electrolyte formulation and formation protocols of solid–electrolyte interphases for enhanced battery cyclability.

25 ENERGY STORAGE↗
DOE OSTI2014

Average structure and local configuration of excess oxygen in UO2+x

Determination of the local configuration of interacting defects in a crystalline, periodic solid is problematic because defects typically do not have a long-range periodicity. Uranium dioxide, the primary fuel for fission reactors, exists in hyperstoichiometric form, UO2+x. Those excess oxygen atoms occur as interstitial defects, and these defects are not random but rather partially ordered. The widely-accepted model to date, the Willis cluster based on neutron diffraction, cannot be reconciled with the first-principles molecular dynamics simulations present here. We demonstrate that the Willis cluster is a fair representation of the numerical ratio of different interstitial O atoms; however, the model does not represent the actual local configuration. The simulations show that the average structure of UO2+x involves a combination of defect structures including split di-interstitial, di-interstitial, mono-interstitial, and the Willis cluster, and the latter is a transition state that provides for the fast diffusion of the defect cluster. The results provide new insights in differentiating the average structure from the local configuration of defects in a solid and the transport properties of UO2+x.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Localized High Concentration Electrolyte Behavior near a Lithium-Metal Anode Surface

Wide-scale practical application of rechargeable lithium-metal batteries remains a significant challenge due to dendrite growth. To overcome this challenge, electrolytes must be designed to allow for the formation of protective solid electrolyte interphase (SEI) layers on the highly reactive lithium-metal anode (LMA) surfaces. Recently, novel localized high-concentration electrolytes (LHCEs) were introduced as a potential solution to enable dendrite-free cycling of LMAs, by using an inert solvent to “dilute” the high concentration electrolytes. Ideally, the diluent itself does not dissolve the salt but is miscible with the solvent to form a localized high concentrated salt/solvent cluster surrounded by the diluent. However, detailed structure and potential surface reactions that may take place in LHCE environment are not yet clear. In this work, we investigated the reactivity of a 1M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of dimethoxyethane (DME)/Tris(2,2,2-trifluoroethyl)orthoformate (TFEO) (1:3 by mol) electrolyte near a Li metal surface based on density functional theory and ab-initio molecular dynamics (MD) simulations. Selected liquid interfacial configurations were obtained from classical MD simulasults indicate that when salt and TFEO molecules are close to each other and to the surface, fluorine anions resulting from the fast salt anion decomposition can trigger a cascade of reactions that lead to the decomposition of TFEO. However, if the Li cation is initially solvated by DME and the anion forming a complex, the stability of the anion increases significantly. The Li solvated structure is implied in the LHCE concept; however statistically the larger amount of TFEO molecules suggest also the first scenario leading to TFEO decomposition. Therefore, the broader implication of our simulations is that the defluorination of TFEO may contribute, together with the anion decomposition, to the observed rapid formation of a stable SEI on the surface of the lithium metal; consequently, favorably affecting the stability of LMAs during battery operation.

Zheng, Yu↗
DOE OSTI2014

Photoluminescence lineshape and dynamics of localized excitonic transitions in InAsP epitaxial layers

The excitonic radiative transitions of InAs{sub x}P{sub 1−x} (x = 0.13 and x = 0.40) alloy epitaxial layers were studied through magnetic field and temperature dependent photoluminescence and time-resolved photoluminescence spectroscopy. While the linewidth and lineshape of the exciton transition for x = 0.40 indicate the presence of alloy broadening due to random anion distribution and the existence of localized exciton states, those of x = 0.13 suggest that this type of compositional disorder is absent in x = 0.13. This localization is further supported by the behavior of the exciton transitions at low temperature and high magnetic fields. InAs{sub 0.4}P{sub 0.6} exhibits anomalous “S-shaped” temperature dependence of the excition emission peak below 100 K as well as linewidth broadening at high magnetic fields due to the compression of the excitonic volume amid compositional fluctuations. Finally, photoluminescence decay patterns suggest that the excitons radiatively relax through two channels, a fast and a slow decay. While the lifetime of the fast decay is comparable for both compositions (∼30 ps), that of the slow decay increases from 206 ps to 427 ps as x increases from 0.13 to 0.40, attributable to carrier migration between the localization states of InAs{sub 0.4}P{sub 0.6}.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗