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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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Modeling Load Dynamics to Support Resiliency-based Operations in Low-Inertia Microgrids
Microgrids have repeatedly demonstrated the ability to provide uninterrupted service to critical end-use loads during normal outages, severe weather events, and natural disasters. While their ability to provide critical services is well documented, microgrids present a more dynamic operational environment than grid-connected distribution systems. The dynamics of a microgrid are commonly driven by the high inertia of rotating generators, which are common in many microgrids. In such high-inertia systems, the impact of end-use load dynamics are often not examined. However, with the increased penetration of inverter-based generation with little or no inertia, it is necessary to consider the impact that the dynamics of the end-use loads have on the operations of microgrids, particularly for a resiliency-based operation. These operations include, but are not limited to, switching operations, loss of generating units, and the starting of induction motors. This paper examines the importance of including dynamic models of the end-use load when evaluating the operations of low inertia microgrids, and shows that by properly representing their behavior, it is possible to cost effectively size equipment while supporting resilient operations of critical end-use loads.
Nanomineralogy as a new dimension in understanding elusive geochemical processes in soils: The case of low-solubility-index elements
Nanomineralogical studies of mineral surface coatings in soils reveal insights into biogeochemical processes that heretofore were not known to exist. This is a new dimension in understanding past and present biogeochemical processes in soils, and in this study it is a way to better understand the behavior of low-solubility-index elements such as Al, Ti, and Zr. Soils were sampled from selected sites in Sudbury (Ontario, Canada) that have been affected by acidification and particulate matter emissions from base-metal smelters with subsequent remediation within the past century. These anthropogenic processes have affected an entire landscape, but are now recorded in assemblages of nano-size phases that can be only studied using a combination of focused ion beam technology (for sample preparation) and high-resolution analytical transmission electron microscopy (for phase identification). A first generation of clay minerals (pre-acidification phase), their partial replacement by nano-size hematite and amorphous silica (anthropogenic acidification), and a second generation of clay minerals (post-acidification, including soil remediation) are products of changes in soil biogeochemical processes during these natural and anthropogenic-induced weathering stages. Furthermore, complex assemblages of nanophases formed prior to the second generation of clay minerals depict underlying mechanisms for the mobilization and sequestration of the low-solubility-index elements Zr and Ti under acidic conditions. The occurrence of baddeleyite (ZrO 2 ), anatase (TiO 2 ), and the Magneli phases Ti 4 O 7 and Ti 5 O 9 (all present at the nanoscale) suggest an influx of nanocolloidal Zr and Ti oxides during weathering of smelter-derived particulate matter. Kelyshite {NaZr[Si 2 O 6 (OH)]}, authigenic zircon (ZrSiO 4 ), and kleberite [Fe 3+ Ti 6 O 11 (OH) 5 ] are most likely products of the sequestration of the Zr- and Ti-bearing nanocolloids.
A Preconditioned Low-Rank Projection Method with a Rank-Reduction Scheme for Stochastic Partial Differential Equations
Herein, we consider the numerical solution of large systems of linear equations obtained from the stochastic Galerkin formulation of stochastic partial differential equations. We propose an iterative algorithm that exploits the Kronecker product structure of the linear systems. The proposed algorithm efficiently approximates the solutions in low-rank tensor format. Using standard Krylov subspace methods for the data in tensor format is computationally prohibitive due to the rapid growth of tensor ranks during the iterations. To keep tensor ranks low over the entire iteration process, we devise a rank-reduction scheme that can be combined with the iterative algorithm. The proposed rank-reduction scheme identifies an important subspace in the stochastic domain and compresses tensors of high rank on-the-fly during the iterations. The proposed reduction scheme is a coarse-grid method in that the important subspace can be identified inexpensively in a coarse spatial grid setting. The efficiency of the present method is displayed by numerical experiments on benchmark problems.
A Low-Rank Multigrid Method for the Stochastic Steady-State Diffusion Problem
We study a multigrid method for solving large linear systems of equations with tensor product structure here. Such systems are obtained from stochastic finite element discretization of stochastic partial differential equations such as the steady-state diffusion problem with random coefficients. When the variance in the problem is not too large, the solution can be well approximated by a low-rank object. In the proposed multigrid algorithm, the matrix iterates are truncated to low rank to reduce memory requirements and computational effort. The technique is proved convergent with an analytic error bound. Numerical experiments show its effectiveness in solving the Galerkin systems compared to the original multigrid solver, especially when the number of degrees of freedom associated with the spatial discretization is large.
Genome Wide Evaluation of Normal Human Tissue in Response to Controlled, In vivo Low-Dose Low LET Ionizing Radiation Exposure: Pathways and Mechanisms (Final Report)
During course of this project, we have worked in several areas relevant to low-dose ionizing radiation. Using gene expression to measure biological response, we have examined the response of human skin exposed in-vivo to radation, human skin exposed ex-vivo to radiation, and a human-skin model exposed to radiation. We have learned a great deal about the biological response of human skin to low-dose ionizing radiation.
Low-Latency Science Exploration of Planetary Bodies: How ISS Might Be Used as Part of a Low-Latency Analog Campaign for Human Exploration
We suggest that the International Space Station be used to examine the application and validation of low-latency telepresence for surface exploration from space as an alternative, precursor, or potentially as an adjunct to astronaut "boots on the ground." To this end, controlled experiments that build upon and complement ground-based analog field studies will be critical for assessing the effects of different latencies (0 to 500 milliseconds), task complexity, and alternate forms of feedback to the operator. These experiments serve as an example of a pathfinder for NASA's roadmap of missions to Mars with low-latency telerobotic exploration as a precursor to astronaut's landing on the surface to conduct geological tasks.
Enhanced Damage in Bipolar Devices at Low Dose Rates: Effects at Very Low Dose Rates*
The effect of very low dose rates and equivalence of high-temperature irradiation are investigated for several device types that are sensitive to enhanced low dose-rate damage. New results are included at 0.001 rad(si)/s.
Li-Ion Synaptic Transistor for Low Power Analog Computing
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A Low-Swelling Polymeric Mixed Conductor Operating in Aqueous Electrolytes
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High-Performance High-Loading Lithium-Sulfur Batteries by Low Temperature Atomic Layer Deposition of Aluminum Oxide on Nanophase S Cathodes
This study examines the effects of nanophase S and surface coatings via atomic layer deposition (ALD) on high-loading sulfur cathodes for developing high-performance and high-energy lithium-sulfur (Li-S) batteries. It is first verified that ball milling is an effective and facile route for nanoengineering microsized S powders and the resultant nanoscale S particles exhibit better performance. Using these ball milled nanoscale S cathodes, it is found that ALD Al2O3 performed at 50 degrees C yields deposits that evolve with ALD cycles from dispersed nanoparticles, to porous, connected films, and finally to dense and continuous films. Moreover, this low temperature ALD process suppresses S loss by sublimation. The ALD Al2O3 greatly improves sulfur cathode sustainable capacity and Coulombic efficiency. This study postulates two different mechanisms underlying the effects of ALD Al2O3 surface coatings depending on their morphology. ALD Al2O3 nanoparticles dispersed on the sulfur surface mainly function to adsorb polysulfides, thereby inhibiting S shuttling and improving sustainable capacity and Coulombic efficiency. By contrast, ALD Al2O3 films behave as a physical barrier to prevent polysulfides from contacting the liquid electrolyte and dissolving. The dispersed Al2O3 nanoparticles improve both sustainable capacity and Coulombic efficiency while the closed Al2O3 films improve Coulombic efficiency while decreasing the capacity
Long Cycle Life, Low Self-Discharge Sodium-Selenium Batteries with High Selenium Loading and Suppressed Polyselenide Shuttling
The utilization of selenium as a cathode in rechargeable sodium–selenium batteries is hampered by low Se loading, inferior electrode kinetics, and polyselenide shuttling between the cathode and anode. Here a high-performance sodium–selenium cell is presented by coupling a binder-free, self-interwoven carbon nanofiber–selenium cathode with a light-weight carbon-coated bifunctional separator. With this strategy, electrodes with a high Se mass loading (4.4 mg cm -2 ) render high reversible capacities of 599 mA h g -1 at 0.1C rate and 382 mA h g -1 at 5C rate. In addition, this novel cell offers good shelf-life with a low self-discharge, retaining 93.4% of its initial capacity even after resting for six months. As evidenced by experimental and density functional theory analysis, the remarkable dynamic (cycle life) and static (shelf-life) stabilities originate from the high electrical conductivity, improved Na-ion accessibility through the 3D interconnected open channels, and highly restrained polyselenide shuttle. The findings demonstrate the viability of high-performance sodium–selenium batteries with high selenium loading.
Low-Barrier and Canonical Hydrogen Bonds Modulate Activity and Specificity of a Catalytic Triad
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Cyanohydridoborate Anions: Synthesis, Salts, and Low‐Viscosity Ionic Liquids
Abstract High‐yield syntheses up to molar scales for salts of [BH(CN) 3 ] − ( 2 ) and [BH 2 (CN) 2 ] − ( 3 ) starting from commercially available Na[BH 4 ] (Na 5 ), Na[BH 3 (CN)] (Na 4 ), BCl 3 , (CH 3 ) 3 SiCN, and KCN were developed. Direct conversion of Na 5 into K 2 was accomplished with (CH 3 ) 3 SiCN and (CH 3 ) 3 SiCl as a catalyst in an autoclave. Alternatively, Na 5 is converted into Na[BH{OC(O) R } 3 ] ( R =alkyl) that is more reactive towards (CH 3 ) 3 SiCN and thus provides an easy access to salts of 2 . Some reaction intermediates were identified, for example, Na[BH(CN){OC(O)Et} 2 ] (Na 7 b ) and Na[BH(CN) 2 {OC(O)Et}] (Na 8 b ). A third entry to 2 and 3 uses ether adducts of BHCl 2 or BH 2 Cl such as the commercial 1,4‐dioxane adducts that react with KCN and (CH 3 ) 3 SiCN. Alkali metal salts of 2 and 3 are convenient starting materials for organic salts, especially for low viscosity ionic liquids (ILs). [EMIm] 3 has the lowest viscosity and highest conductivity with 10.2 mPa s and 32.6 mS cm −1 at 20 °C known for non‐protic ILs. The ILs are thermally, chemically, and electrochemically robust. These properties are crucial for applications in electrochemical devices, for example, dye‐sensitized solar cells (Grätzel cells).
Synthesis of High-Performance Monolayer Molybdenum Disulfide at Low Temperature
Not provided.