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At least 1,081 records · Page 60
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Electrorefining Bismuth Using AC Superimposed DC Waveforms

Bismuth has been successfully electrorefined using both direct current (DC) and alternating current (AC) superimposed DC waveforms on a kilogram scale at Brigham Young University (BYU) in Provo, Utah. Finding a suitable surrogate for Pu Electrorefining has always been a technical challenge. This work allows the possibility to improve Pu electrorefining with nonradioactive material at universities, which greatly reduces the cost at Lawrence Livermore National Laboratory (LLNL) for improving Pu Electrorefining. Several possible surrogates (Ce, In, Sn, Zn, and Bi) were selected based on their ability to mimic the Pu electrorefining process. Ce and In electrorefining experiments were conducted at the same temperature as Pu electrorefining in CaCl 2 while Sn, Zn, and Bi, electrorefining experiments were conducted at a lower temperature in a eutectic molten salt composed of LiCl, KCl, and CaCl 2 . The electrorefining experiments using Ce with a Ga impurity did not produce a cathode ring. While the remaining Ce anode after electrorefining was significantly less than what was initially added, Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX) analysis showed that the Ce had been oxidized and formed a colloid with the surrounding molten salt. This is supported in the literature by analysis of Ce-rich CaCl 2 mixtures. All the electrorefining experiments except for the Ce electrorefining experiments did not introduce an impurity to the system. Electrorefining experiments with In showed that the InCl 3 volatilized out of the molten salt to an extent that only a low current (<<1 A) could be supported without decomposing the molten salt. Zn electrorefining experiments had marginal success, however an easily separable product was not formed. The Zn had to be rinsed from the salt after the experiment. Of the identified potential surrogates. Investigated, only Bi and Sn yielded an easily separable product ring, which enables quantitative analysis of yields and coulombic efficiencies. Bismuth was first identified as a surrogate at BYU, while Sn was identified as a surrogate at LLNL later. Thus, the electrorefining experiments conducted at BYU using AC superimposed DC waveforms used Bi as the metal to be electrorefined.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Wrought Aluminum-Cerium Alloys by Shear Assisted Processing and Extrusion

Al-Ce alloys have attracted recent interest because of their high thermal stability due to the very low solubility of Ce in the Al matrix. The Al 11 Ce 3 eutectic phase gives excellent strain hardening behavior and moderate high-temperature strength in the as-cast state. However, its strengthening effect is limited by its coarse as-cast structure. Therefore, alternative manufacturing methods such as additive manufacturing or equal channel angular pressing have been applied to refine the Al 11 Ce 3 phase to good effect. However, these techniques are both expensive and time-consuming. Therefore, this study aims to use Shear Assisted Processing and Extrusion (ShAPE), an emerging solid phase processing technique that is more easily scalable than the previously mentioned methods. ShAPE can produce useful cross-sections of an Al-8Ce-4Mg alloy while refining the Al 11 Ce 3 phase to produce a higher strength material. It was found that a low temperature ShAPE process can improve the room temperature yield strength by ~60% compared to a binary Al-4Mg alloy. Additionally, the high-temperature yield strength of the Al-Ce alloys increased by 20%, with a simultaneous 15% improvement in ductility compared to the binary Al-Mg alloy. These results highlight the potential for ShAPE as a processing technique for Al-Ce alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Super Resolving Unrolled Neural Networks for Remote Sensing

In remote sensing systems, the capabilities of the system are constrained by the complex interactions between size, weight, and power (SWAP) of potential designs. In electro-optical (EO) systems, examples of these critical parameters include the system’s sensitivity and resolution. Those parameters can be increased by ever larger optical apertures and focal planes but at the cost of more SWAP. Multi-image super resolution (MISR) techniques allow resolution to be enhanced via computation rather than more sophisticated optical hardware. These algorithms combine multiple images together into a single, higher resolution image, trading temporal resolution and computation for spatial resolution. Fielded MISR techniques, such as Drizzle, can require several hundred images to create a single super resolved image, implying reduced temporal resolution, increased data acquisition load, and limiting mission applications. Iterative techniques, such as model-based image reconstruction and compressive sensing, have been shown to create super resolved images using fewer images than Drizzle. They do this by posing an optimization problem that balances accuracy between a highly accurate physical model and an image model. In the case of super resolution, the physical model is defined by the relation between low resolution input images and the desired high resolution output image. The image model encodes some assumptions about the super resolved image. These assumptions are meant to suppress reconstruction artifacts that arise due to deterministic physical model error, stochastic measurement noise, and potential undersampling. In practice, the performance of iterative methods are limited by imaging models compatible with optimization. Deep learning-based methods can effectively learn image models of arbitrary complexity, but lack the theoretical explainability and robustness of iterative techniques. Consensus equilibrium (CE) generalizes the iterative techniques beyond optimization, enabling blackbox algorithms such as traditional and neural image denoisers to be used as the image model. CE-based approaches retain much of the explainability and robustness of iterative techniques while allowing the expressiveness of machine learning image models to be used. Additionally, by unrolling iterations of CE with an embedded image denoiser, the image denoiser can be further trained and specialized to the specific application with potentially higher quality reconstructions. Under this project, we demonstrated the feasibility of training an unrolled neural network based upon CE. While we didn’t train one, we showed that the CE process is differentiable and its gradient can be tractably computed. We also explored the usage of a variants of CE akin to generative neural works. Most importantly, we applied the CE framework to a number of problems including non-blind deconvolution, upsampling, single-image super resolution, MISR, event-based sensing, and saturated deconvolution. Our MISR prototype creates high quality reconstructions with an order of magnitude fewer images than previous approaches and, critically, produces these reconstructions fast enough for practical usage.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

Active Galactic Nuclei Continuum Reverberation Mapping Based on Zwicky Transient Facility Light Curves

We perform a systematic survey of active galactic nuclei (AGNs) continuum lags using ~3 days cadence gri-band light curves from the Zwicky Transient Facility. We select a sample of 94 type 1 AGNs at z < 0.8 with significant and consistent inter-band lags based on the interpolated cross-correlation function method and the Bayesian method JAVELIN. Within the framework of the "lamp-post" reprocessing model, our findings are: (1) The continuum emission (CE) sizes inferred from the data are larger than the disk sizes predicted by the standard thin-disk model. (2) For a subset of the sample, the CE size exceeds the theoretical limit of the self-gravity radius (12 lt-days) for geometrically thin disks. (3) The CE size scales with continuum luminosity as R CE ∝ L 0.48±0.04 with a scatter of 0.2 dex, analogous to the well-known radius–luminosity relation of broad Hβ. These findings suggest a significant contribution of diffuse continuum emission from the broad-line region (BLR) to AGN continuum lags. We find that the R CE –L relation can be explained by a photoionization model that assumes ~23% of the total flux comes from the diffuse BLR emission. In addition, the ratio of the CE size and model-predicted disk size anticorrelates with the continuum luminosity, which is indicative of a potential nondisk BLR lag contribution evolving with the luminosity. Finally, a robust positive correlation between the CE size and black hole mass is detected.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Controlled Environment Agriculture - Farming and Food Access for Healthy Diets

Fruits and vegetables are critical for a healthy diet and USDA guidelines recommend increasing fruit and vegetable consumption for almost all Americans. However, most food system lifecycle assessments do not capture the importance of these food groups in the food system. Moreover, long supply chains and limited access to fresh produce are particularly prevalent in disadvantaged neighborhoods. Many of these communities are food deserts or food swamps characterized by a lack of full-scale groceries, and a prevalence of convenience stores and fast-food restaurants. Stocking of fresh produce is difficult and often unprofitable for small stores. Convenience stores are usually space-limited, unable to achieve economies-of-scale in purchasing and have difficulty managing the short shelf-life of fresh produce. Controlled-Environment (CE) farming, including greenhouses and fully indoor vertical farms, have the potential to address persistent food access issues for disadvantaged communities. CE farming offers several potential advantages for food desert and food swamp neighborhoods, including shorter or non-existent transport distances and fewer middlemen, which could reduce costs. CE farming can be integrated into existing buildings at virtually any scale, providing local jobs and revitalization of community hubs such as shopping malls, or larger-scale farms located in close-in warehouse or industrial areas. Rainwater harvesting and recovery of nutrients from wastewater could further improve food system resilience and circularity. Geospatial modeling of CE farming in case study cities of various sizes and densities will help to quantify the benefits of CE farming. Geospatial modeling can help to answer questions such as whether sufficient collection area is available for rainwater harvesting for a CE farm, and what size of farm would be required to serve the community living within walking distance of the farm. This paper reports on progress in geospatial modeling of CE farming integration into several case study cities.

controlled environment agriculture↗
DOE OSTI2023

Tuning the Interaction between Platinum Single Atoms and Ceria by Zirconia Doping for Efficient Catalytic Ammonia Oxidation

Aiming at the development of an efficient NH 3 oxidation catalyst to eliminate the harmful NH 3 slip from the stationary flue gas denitrification system and diesel exhaust aftertreatment system, a facile ZrO 2 doping strategy was proposed to construct Pt 1 /Ce x Zr 1–x O 2 catalysts with a tunable Pt-CeO 2 interaction strength and Pt–O–Ce coordination environment. According to the results of systematic characterizations, Pt species supported on Ce x Zr 1–x O 2 were mainly in the form of single atoms when x ≥ 0.7, and the strength of the Pt-CeO 2 interaction and the coordination number of Pt–O–Ce bond (CN Pt–O–Ce ) on Pt 1 /Ce x Zr 1–x O 2 showed a volcanic change as a function of the ZrO 2 doping amount. Here, it was proposed that the balance between the reasonable concentration of oxygen defects and limited surface Zr–O x species well accounted for the strongest Pt-CeO 2 interaction and the highest CN Pt–O–Ce on Pt/Ce 0.9 Zr 0.1 O 2 . It was observed that the Pt/Ce 0.9 Zr 0.1 O 2 catalyst exhibited much higher NH 3 oxidation activity than other Pt/Ce x Zr 1–x O 2 catalysts. The mechanism study revealed that the Pt 1 species with the stronger Pt-CeO 2 interaction and higher CN Pt–O–Ce within Pt/Ce 0.9 Zr 0.1 O 2 could better activate NH 3 adsorbed on Lewis acid sites to react with O 2 thus resulting in superior NH 3 oxidation activity. This work provides a new approach for designing highly efficient Pt/CeO 2 based catalysts for low-temperature NH 3 oxidation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeCdAu by Materials Project

CeAuCd crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Au and six equivalent Cd atoms. There are four shorter (3.15 Å) and one longer (3.22 Å) Ce–Au bond lengths. There are two shorter (3.35 Å) and four longer (3.48 Å) Ce–Cd bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Cd atoms. All Au–Cd bond lengths are 2.88 Å. In the second Au site, Au is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Cd atoms. All Au–Cd bond lengths are 2.99 Å. Cd is bonded in a 4-coordinate geometry to six equivalent Ce and four Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeAlNi by Materials Project

CeNiAl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 5-coordinate geometry to five Ni and six equivalent Al atoms. There are four shorter (2.88 Å) and one longer (2.92 Å) Ce–Ni bond lengths. There are two shorter (3.11 Å) and four longer (3.24 Å) Ce–Al bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Al atoms. All Ni–Al bond lengths are 2.58 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Al atoms. All Ni–Al bond lengths are 2.71 Å. Al is bonded in a 12-coordinate geometry to six equivalent Ce, four Ni, and two equivalent Al atoms. Both Al–Al bond lengths are 2.77 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2(Zn2Ge)3 by Materials Project

Ce2(Zn2Ge)3 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 6-coordinate geometry to nine Zn and six equivalent Ge atoms. There are three shorter (3.25 Å) and six longer (3.45 Å) Ce–Zn bond lengths. All Ce–Ge bond lengths are 3.13 Å. There are two inequivalent Zn sites. In the first Zn site, Zn is bonded in a 3-coordinate geometry to four equivalent Ce, four equivalent Zn, and three equivalent Ge atoms. All Zn–Zn bond lengths are 2.80 Å. There are one shorter (2.53 Å) and two longer (2.67 Å) Zn–Ge bond lengths. In the second Zn site, Zn is bonded in a distorted water-like geometry to two equivalent Ce, six Zn, and two equivalent Ge atoms. Both Zn–Zn bond lengths are 2.53 Å. Both Zn–Ge bond lengths are 2.55 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ce and five Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeAg by Materials Project

CeAg is Tetraauricupride structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ce is bonded to four equivalent Ce and eight equivalent Ag atoms to form distorted CeCe4Ag8 cuboctahedra that share corners with twelve equivalent CeCe4Ag8 cuboctahedra, edges with eight equivalent CeCe4Ag8 cuboctahedra, edges with sixteen equivalent AgCe8Ag4 cuboctahedra, faces with eight equivalent AgCe8Ag4 cuboctahedra, and faces with ten equivalent CeCe4Ag8 cuboctahedra. All Ce–Ce bond lengths are 3.20 Å. All Ce–Ag bond lengths are 3.24 Å. Ag is bonded to eight equivalent Ce and four equivalent Ag atoms to form distorted AgCe8Ag4 cuboctahedra that share corners with twelve equivalent AgCe8Ag4 cuboctahedra, edges with eight equivalent AgCe8Ag4 cuboctahedra, edges with sixteen equivalent CeCe4Ag8 cuboctahedra, faces with eight equivalent CeCe4Ag8 cuboctahedra, and faces with ten equivalent AgCe8Ag4 cuboctahedra. All Ag–Ag bond lengths are 3.20 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeSnRh by Materials Project

CeRhSn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Rh and six equivalent Sn atoms. There are four shorter (3.04 Å) and one longer (3.10 Å) Ce–Rh bond lengths. There are two shorter (3.23 Å) and four longer (3.39 Å) Ce–Sn bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Sn atoms. All Rh–Sn bond lengths are 2.78 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Sn atoms. All Rh–Sn bond lengths are 2.85 Å. Sn is bonded in a 10-coordinate geometry to six equivalent Ce and four Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2Ga10Pd by Materials Project

Ce2PdGa10 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to sixteen Ga atoms. There are a spread of Ce–Ga bond distances ranging from 3.27–3.54 Å. Pd is bonded in a body-centered cubic geometry to eight equivalent Ga atoms. All Pd–Ga bond lengths are 2.60 Å. There are four inequivalent Ga sites. In the first Ga site, Ga is bonded in a 9-coordinate geometry to four equivalent Ce and five Ga atoms. There are one shorter (2.41 Å) and four longer (2.60 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 9-coordinate geometry to four equivalent Ce and five Ga atoms. All Ga–Ga bond lengths are 2.62 Å. In the third Ga site, Ga is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent Ga atoms. In the fourth Ga site, Ga is bonded in a 2-coordinate geometry to two equivalent Ce, two equivalent Pd, and two equivalent Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeSi3Ru by Materials Project

CeRuSi3 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. Ce is bonded in a 4-coordinate geometry to five equivalent Ru and twelve Si atoms. There are four shorter (3.37 Å) and one longer (3.40 Å) Ce–Ru bond lengths. There are a spread of Ce–Si bond distances ranging from 3.05–3.41 Å. Ru is bonded in a 5-coordinate geometry to five equivalent Ce and five Si atoms. There are one shorter (2.34 Å) and four longer (2.36 Å) Ru–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded in a distorted bent 120 degrees geometry to four equivalent Ce, two equivalent Ru, and two equivalent Si atoms. Both Si–Si bond lengths are 2.61 Å. In the second Si site, Si is bonded in a 1-coordinate geometry to four equivalent Ce, one Ru, and four equivalent Si atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeGe3Rh by Materials Project

CeRhGe3 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to five equivalent Rh and twelve Ge atoms. There are one shorter (3.37 Å) and four longer (3.54 Å) Ce–Rh bond lengths. There are eight shorter (3.22 Å) and four longer (3.47 Å) Ce–Ge bond lengths. Rh is bonded in a 5-coordinate geometry to five equivalent Ce and five Ge atoms. There are one shorter (2.40 Å) and four longer (2.44 Å) Rh–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 2-coordinate geometry to four equivalent Ce, two equivalent Rh, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.73 Å. In the second Ge site, Ge is bonded in a 1-coordinate geometry to four equivalent Ce, one Rh, and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeGe3Ir by Materials Project

CeIrGe3 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to five equivalent Ir and twelve Ge atoms. There are one shorter (3.41 Å) and four longer (3.54 Å) Ce–Ir bond lengths. There are eight shorter (3.23 Å) and four longer (3.49 Å) Ce–Ge bond lengths. Ir is bonded in a 5-coordinate geometry to five equivalent Ce and five Ge atoms. There are one shorter (2.41 Å) and four longer (2.45 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 2-coordinate geometry to four equivalent Ce, two equivalent Ir, and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.73 Å. In the second Ge site, Ge is bonded in a 1-coordinate geometry to four equivalent Ce, one Ir, and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeZnPd by Materials Project

CePdZn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Pd and six equivalent Zn atoms. There are four shorter (2.99 Å) and one longer (3.02 Å) Ce–Pd bond lengths. There are two shorter (3.23 Å) and four longer (3.30 Å) Ce–Zn bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Zn atoms. All Pd–Zn bond lengths are 2.68 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Zn atoms. All Pd–Zn bond lengths are 2.84 Å. Zn is bonded in a 4-coordinate geometry to six equivalent Ce and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2Al2Co15 by Materials Project

Ce2Al2Co15 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ce is bonded in a 3-coordinate geometry to fifteen Co and one Al atom. There are a spread of Ce–Co bond distances ranging from 2.88–3.17 Å. The Ce–Al bond length is 3.06 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded to two equivalent Ce, eight Co, and two equivalent Al atoms to form a mixture of distorted corner, edge, and face-sharing CoCe2Al2Co8 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.39–2.59 Å. Both Co–Al bond lengths are 2.72 Å. In the second Co site, Co is bonded to three equivalent Ce, eight Co, and one Al atom to form a mixture of distorted corner, edge, and face-sharing CoCe3AlCo8 cuboctahedra. There are two shorter (2.41 Å) and two longer (2.46 Å) Co–Co bond lengths. The Co–Al bond length is 2.59 Å. In the third Co site, Co is bonded in a 12-coordinate geometry to eight Co and two equivalent Al atoms. Both Co–Al bond lengths are 2.52 Å. Al is bonded in a 6-coordinate geometry to one Ce, twelve Co, and one Al atom. The Al–Al bond length is 2.60 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeInAu by Materials Project

CeAuIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 5-coordinate geometry to five Au and six equivalent In atoms. There are four shorter (3.18 Å) and one longer (3.19 Å) Ce–Au bond lengths. There are two shorter (3.39 Å) and four longer (3.52 Å) Ce–In bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent In atoms. All Au–In bond lengths are 2.89 Å. In the second Au site, Au is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent In atoms. All Au–In bond lengths are 2.96 Å. In is bonded in a 4-coordinate geometry to six equivalent Ce and four Au atoms.

36 MATERIALS SCIENCE↗