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Results for “high performance analytics”

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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

High-throughput ab initio reaction mechanism exploration in the cloud with automated multi-reference validation

Quantum chemical calculations on atomistic systems have evolved into a standard approach to studying molecular matter. These calculations often involve a significant amount of manual input and expertise, although most of this effort could be automated, which would alleviate the need for expertise in software and hardware accessibility. Here, we present the AutoRXN workflow, an automated workflow for exploratory high-throughput electronic structure calculations of molecular systems, in which (i) density functional theory methods are exploited to deliver minimum and transition-state structures and corresponding energies and properties, (ii) coupled cluster calculations are then launched for optimized structures to provide more accurate energy and property estimates, and (iii) multi-reference diagnostics are evaluated to back check the coupled cluster results and subject them to automated multi-configurational calculations for potential multi-configurational cases. All calculations are carried out in a cloud environment and support massive computational campaigns. Key features of all components of the AutoRXN workflow are autonomy, stability, and minimum operator interference. We highlight the AutoRXN workflow with the example of an autonomous reaction mechanism exploration of the mode of action of a homogeneous catalyst for the asymmetric reduction of ketones.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Vertically assembled nanosheet networks for high-density thick battery electrodes

As one of the prevailing energy storage systems, lithium-ion batteries (LIBs) have become an essential pillar in electric vehicles (EVs) during the past decade, contributing significantly to a carbon-neutral future. However, the complete transition to electric vehicles requires LIBs with yet higher energy and power densities. Here, we propose an effective methodology via controlled nanosheet self-assembly to prepare low-tortuosity yet high-density and high-toughness thick electrodes. By introducing a delicate densification in a three-dimensionally interconnected nanosheet network to maintain its vertical architecture, facile electron and ion transports are enabled despite their high packing density. This dense and thick electrode is capable of delivering a high volumetric capacity >1,600 mAh cm −3 , with an areal capacity up to 32 mAh cm −2 , which is among the best reported in the literature. The high-performance electrodes with superior mechanical and electrochemical properties demonstrated in this work provide a potentially universal methodology in designing advanced battery electrodes with versatile anisotropic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Direct Chemical Vapor Deposition Synthesis of Porous Single-Layer Graphene Membranes with High Gas Permeances and Selectivities

Single-layer graphene containing molecular-sized in-plane pores is regarded as a promising membrane material for high-performance gas separations due to its atomic thickness and low gas transport resistance. However, typical etching-based pore generation methods cannot decouple pore nucleation and pore growth, resulting in a trade-off between high areal pore density and high selectivity. In contrast, intrinsic pores in graphene formed during chemical vapor deposition are not created by etching. Therefore, intrinsically porous graphene can exhibit high pore density while maintaining its gas selectivity. Here in this work, the density of intrinsic graphene pores is systematically controlled for the first time, while appropriate pore sizes for gas sieving are precisely maintained. As a result, single-layer graphene membranes with the highest H 2 /CH 4 separation performances recorded to date (H 2 permeance > 4000 GPU and H 2 /CH 4 selectivity > 2000) are fabricated by manipulating growth temperature, precursor concentration, and non-covalent decoration of the graphene surface. Moreover, it is identified that nanoscale molecular fouling of the graphene surface during gas separation where graphene pores are partially blocked by hydrocarbon contaminants under experimental conditions, controls both selectivity and temperature dependent permeance. Overall, the direct synthesis of porous single-layer graphene exploits its tremendous potential as high-performance gas-sieving membranes.

chemical vapor deposition↗
DOE OSTI2022

Oxygen vacancy-rich amorphous FeNi hydroxide nanoclusters as an efficient electrocatalyst for water oxidation

Here, a one-pot strategy is presented to directly synthesize amorphous Fe x Ni y hydroxide nanoclusters (denoted as ANC-Fe x Ni y , <2 nm) with oxygen vacancies induced by ionic liquids. The ANC-Fe x Ni y catalyst presents abundant catalytic sites and high intrinsic conductivity. As such, the optimized ANC-Fe 1 Ni 2 exhibits high activity in oxygen evolution reaction (OER) with a Tafel slope of 39 mV dec –1 and an overpotential of 266 mV at 10 mA cm –2 . Notably, the optimized ANC-Fe 1 Ni 2 shows an extraordinarily large mass activity of 3028 A g FeNi –1 at the overpotential of 300 mV, which is ~24-fold of commercial RuO 2 catalyst. The superior activity of these Fe x Ni y hydroxide nanoclusters is ascribed to (i) the amorphous and distorted structure with abundant oxygen vacancies, and (ii) enhanced active site density by downsizing the ANC-Fe x Ni y clusters. This strategy provides a novel route for enhancing OER electrocatalytic performance and highly encouraging for the future application of amorphous metal hydroxides in catalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

First graded metal pushered single shell capsule implosions on the National Ignition Facility

Graded metal pushered single shell (PSS) capsules are predicted to be a viable alternative to low-Z capsule indirect drive inertial confinement fusion (ICF) implosions for achieving high fusion yields [MacLaren et al., Phys. Plasmas 28, 122710 (2021)]. The first experiments with Be/Cr-graded metal PSS capsules indicate that the implementation of the principle design feature, the graded density inner metal layer, has succeeded in producing a stable implosion with performance in agreement with predictions. With 50% Cr concentration in the pusher, PSS capsules have greater than ~2× higher shell densities during stagnation for enhanced core confinement and radiation trapping at ~35% lower shell implosion velocities than low-Z capsules. High-energy >30 keV inflight shell radiography recorded 215 km/s implosion velocities and show that implosion Legendre mode P 2 asymmetry can be tuned via inner-to-outer beam wavelength separation, similar to other implosions. Shell radiographs and neutron core images show similar P 2 asymmetry, suggesting no symmetry swings between peak implosion velocity and stagnation times. Despite the modest implosion velocities, gas-filled deuterium–tritium capsule implosions generate 10 15 neutron yields at relatively modest core ion temperatures of 2.75 keV, indicating that in spite of the high-density inner layer, the implosions have been stabilized by the design density gradient. When compared with hydrodynamic simulations, the measured yield-over-simulated is 35% due to fuel–pusher mix and other perturbations such as the capsule fill tube. Finally, simple analytical scalings of hot spot pressure and neutron yield show that PSS implosions reach similar performance at lower implosion velocities and higher shell densities to low-Z ICF capsules.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

A Performance Portable, Fully Implicit Landau Collision Operator with Batched Linear Solvers

Modern accelerators use hierarchical parallel programming models that enable massive multithreading within a processing element (PE), with multiple PEs per device driven by traditional processes. Batching is a technique for exposing PE-level parallelism in algorithms that have traditionally run on MPI processes or multiple threads within a single process. Opportunities for batching arise in, for example, kinetic discretizations of magnetized plasmas where collisions are advanced in velocity space at each spatial point independently. This paper builds on previous work on a high-performance, fully nonlinear, Landau collision operator by batching the linear solver, as well as batching the spatial point problems and adding new support for multiple grids for multiscale, multispecies problems. An anisotropic relaxation verification test that agrees well with previously published results and analytical models is presented. The performance results from NVIDIA A100 and AMD MI250X nodes are presented with hardware utilization analysis for each architecture. Finally, the entire implicit Landau operator time advance is implemented in Kokkos for performance portability, running entirely on the device and is available in the PETSc numerical library.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Construction of an Anion-Pillared MOF Database and the Screening of MOFs Suitable for Xe/Kr Separation

The separation of xenon/krypton (Xe/Kr) mixtures is a challenging process. Many porous materials allow the adsorption of both Xe and Kr but only with low selectivity. Anion-pillared metal–organic frameworks (MOFs), featuring the anion groups as structural pillars, show potential in gas separations, but only a limited number of them have been synthesized. Here, we describe a collection of 936 anion-pillared MOFs based on 22 experimentally available structures. We performed density functional theory (DFT) optimization and then assigned density-derived electrostatic and chemical (DDEC) charges for each MOF to make them well suited to molecular simulations. The structural properties of the MOFs vary more strongly with the choice of the organic ligand than with other aspects like fluorine groups and metal centers. We then screened the entire collection of MOFs in the context of Xe/Kr separation at room temperature. Compared with previously reported MOFs, the interpenetrated MOF SIFSIX-6-Cd-i is predicted to perform better for Xe/Kr separations, with a good balance between working capacity (1.62 mmol/g) and separation selectivity (16.4) at 298 K and 100 kPa. Here, we also found that the heterogeneity of fluorine groups within a MOF can help to enhance Xe working capacity without reducing the Xe/Kr selectivity, suggesting that synthesis of anion-pillared MOFs with mixed fluorine groups may lead to improved Xe/Kr separation performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Stabilizing Ni-rich layered cathode for high-voltage operation through hierarchically heterogeneous doping with concentration gradient

High-nickel LiNi x Mn y Co 1-x-y O 2 (NMC) cathodes have demonstrated superior energy density, yet their stability is compromised under high voltage conditions. To address this, here we propose a strategy of heterogeneous doping with a concentration gradient, specifically through Sr–Zr co-modification. We synthesized Ni-rich NMC particles featuring several micron-sized secondary particles composed of micron-sized primary grains. This design aims to harness the structural robustness of single-crystalline grains and the favorable diffusion kinetics of polycrystalline secondary particles. Systematic characterization using a combination of electrochemical measurements and synchrotron analytics reveals an intriguing pattern of hierarchically heterogeneous Sr–Zr co-doping. It demonstrates a depth-dependent concentration gradient at the secondary particle level and competing dopant segregation over the buried grain boundaries. This unique characteristic creates opportunities for enhancing battery performance, particularly by optimizing precursors and implementing advanced modulation techniques. We also investigate the dissolution and precipitation of the cathode's transition metal cations upon high-voltage cycling. These insights suggest that a tailored compositional variation can be a viable approach to effectively design the next-generation high-Ni NMC cathode materials for high-voltage lithium batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Towards Generalizable and Efficient Circuit Topology Design: A Graph-Transformer-based Surrogate Model with Curriculum Learning

Unlike circuit parameter and sizing optimizations, the automated design of analog circuit topologies poses significant challenges for learning-based approaches. One challenge arises from the combinatorial growth of the topology space with circuit size, which limits the topology optimization efficiency. Moreover, traditional circuit evaluation methods are time-consuming, while the presence of data discontinuity in the topology space makes the accurate prediction of circuit performance exceptionally difficult for unseen topologies. To tackle these challenges, we design a novel Graph-Transformer-based Network (GTN) as the surrogate model for circuit evaluation, offering a substantial acceleration in the speed of circuit topology optimization without sacrificing performance. Our GTN model architecture is designed to embed voltage changes in circuit loops and current flows in connected devices, enabling accurate performance predictions for circuits with unseen topologies. To address the cold start problem when scaling GTN to large-scale circuits, we further introduce a curriculum learning strategy that progressively trains GTN from small-scale to large-scale circuits. This approach enables the model to first learn fundamental physical principles from simpler topologies and gradually adapt to complex configurations, effectively bridging the circuit complexity gap and improving prediction accuracy. Taking the power converter circuit design as an experimental task, our GTN model significantly outperforms an analytical approach and baseline methods directly utilizing graph neural networks. Furthermore, GTN achieves less than 5% relative error and 196× speed-up compared with high-fidelity simulation. Notably, our GTN surrogate model empowers an automatic circuit design framework to discover circuits of comparable quality to those identified through high-fidelity simulation while reducing the time required by up to 98.2%. With curriculum learning, the enhanced GTN achieves a 51% improvement for performance prediction of large-scale circuits compared to the GTN model without this strategy. These advancements establish GTN as a scalable framework for automated analog circuit design across varying circuit complexity levels.

Lu, Haoshu [New Jersey Institute of Technology (NJ↗
DOE OSTI2023

Appealing sheath-core spun high-performance composite carbon molecular sieve membranes

Carbon molecular sieve (CMS) membranes are attractive candidates to meet requirements for challenging gas separations. The added ability to maintain such intrinsic properties in an asymmetric morphology with a structure that we term a “Pseudo Wheel+Hub & Spoke” asymmetric form offers new opportunities. For CMS membrane, specifically, the structure provides both selective layer support and low flow resistance even for high feed pressures and fluxes in CO 2 removal from natural gas. Further, this capability is unavailable to even rigid glassy polymers due to the much higher modulus of CMS materials. Combining precursor asymmetric hollow fiber formation and optimized pyrolysis creates a defect free CMS proof-of-concept membrane for this application. Facile formation of the sheath-core spun precursor with a 6FDA-DAM sheath and Matrimid® core also avoids the need to seal defects before or after the carbonization of the precursors. The composite CMS membrane shows CO 2 /CH 4 (50 : 50) mixed gas feed with an attractive CO 2 /CH 4 selectivity of 64.3 and CO 2 permeance of 232 GPU at 35 °C. A key additional benefit of the approach is reduction in use of the more costly high performance 6FDA-DAM in a composite sheath-core CMS membrane with the “Pseudo Wheel+Hub & Spoke” structure.

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

Unleashing the potential of waste: A supercharged high-performance 3D printing resin from discarded polylactic acid

In additive manufacturing/3D printing, the limitation no longer lies in people’s imagination but in the very materials that one can print with. While the additive manufacturing process can virtually create any geometry, available applications are often limited by factors like parts’ mechanical strength, glass transition temperature, and heat deflection temperature. These factors are especially critical for polymer-based printing. Here we introduce a simple formulation derived from the aminolysis of polylactic acid (PLA) plastic waste, namely the N-lactoyl ethanolamine (N-LEA). The N-LEA is next reacted with excess methacrylic anhydride, forming a photo-crosslinkable resin for MSLA 3D printing. The resulting 3D printed part has a set of impressive properties that is unrivaled amongst engineering grade 3D printing resins on the market and research literature. The 3D printed part has an ultrahigh tensile strength of 131.7 MPa, glass transition at ~190 °C, and heat deflection temperature at 162.6 °C. Furthermore, this work demonstrates a true upcycling approach for turning PLA waste into a value-added product in a simple and efficient manner while also expanding the high-performance material portfolio available for photocuring additive manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The importance of cycle-by-cycle data in performing rapid battery technology development and validation

Lithium-ion battery (LiB) technology is playing a crucial role in transforming the predominantly fossil fuel-based transportation and stationary storage sectors to achieve a low-carbon economy. Rapid innovation in the LiB materials to electrode to cell design is happening to satisfy the performance, life, and safety metrics required by those myriads of applications. Lately, advanced analytics, such as machine-learning or artificial intelligence (ML/AI) techniques, are being used more frequently to aid in expedited LiB technology development, performance validation, and life prediction. The success of these techniques often relies on a large volume of well-defined and high-quality battery test data. On the other hand, most battery developers and research and development (R&D) communities are still following a classical approach to develop batteries, which is running calendar- and/or cycle-aging tests, performing reference performance tests (RPTs), and conducting post-mortem analyses periodically without paying attention to the wealth of data often not collected during the calendar or cycle life aging tests. This sparse data collection approach is time- and resource-intensive, requiring data capture and evaluation of months to years of RPT data to diagnose accurate battery state of performance, health, and safety. Even so, the underlying aging modes and mechanisms can be missed. If collected properly, battery test data during cycling or calendaring can be efficiently combined with ML/AI techniques to create powerful tools in the rapid diagnosis of battery state of performance, health, and safety along with insights into underlying aging modes and mechanisms. In this report, we discuss the importance of effective cycle-by-cycle (CBC) data collection with example case studies. Within a reasonable timeframe, RPT data are often inadequate in capturing many of the crucial battery aging dynamics, which often predominantly show up in CBC test data. Finally, we also show examples of ML/AI techniques that use CBC data in rapid diagnosis and projection of LiB state of health (SOH) to motivate the scientific community in collecting and using CBC data to facilitate expeditious technology development and validation.

25 ENERGY STORAGE↗
DOE OSTI2023

Modular Iron–Bipyridine-Based Conjugated Aerogels as Catalysts for Oxygen Reduction Reaction

Aerogels have a large surface area and a porous structure, which make them an attractive catalyst support materials for fuel cells. Modifying the aerogels’ building blocks and introducing catalytic sites into their backbones allow them to function as both catalysts and supports, thereby increasing the density and distribution of catalyst active sites. In this work, we studied conjugated aerogels containing iron–bipyridine catalytic sites for the oxygen reduction reaction. To demonstrate the variation in physical and electrochemical properties of these aerogels, a series of aerogels were synthesized by a Glaser coupling reaction. Iron salt was added to the three-dimensional gel to produce iron–bipyridine complexes and obtain atomically dispersed catalytic sites. The electrocatalytic activity and electrical conductivity of the aerogels were increased after their heat treatment to yield Fe-doped carbon aerogels. The control of metal loadings was accomplished by changing the bipyridine content during the aerogel synthesis, resulting in 0.9–4.1 wt % Fe. In conclusion, the results show a correlation between Fe loading, aerogel structure, and catalytic activity, achieving high performance for the oxygen reduction reaction in both acidic and alkaline media.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Investigations of the stability of GaAs for photoelectrochemical H 2 evolution in acidic or alkaline aqueous electrolytes

The long-term stability of p-GaAs photocathodes has been investigated for the hydrogen-evolution reaction (HER) in contact with either 1.0 M H 2 SO 4 (aq) or 1.0 M KOH(aq). Stability for the HER was evaluated using p-GaAs electrodes that were either etched or coated with active HER catalysts (Pt and CoP). Changes in surface characteristics of GaAs after exposure to electrochemical conditions were monitored by X-ray photoelectron spectroscopy (XPS), and electrode dissolution processes were evaluated by inductively coupled plasma mass spectrometry (ICP-MS). Consistent with thermodynamic predictions, after operation of the HER at pH 0 or pH 14, illuminated etched p-GaAs electrodes exhibited minimal dissolution while preserving a nearly stoichiometric surface. Electrodeposition or sputtering of Pt on the p-GaAs surface promoted the formation of excess As 0 via an interfacial reaction during the HER. The resulting non-stoichiometric As 0 -rich surface of p-GaAs/Pt electrodes caused a loss in photoactivity as well as substantial cathodic dark current. In contrast, p-GaAs electrodes coated with thin-film CoP catalysts did not display an increase in surficial As 0 after operation of the HER in acidic electrolytes. Minimization of deleterious interfacial reactions is thus critical to obtain extended stability in conjunction with high performance from p-GaAs photocathodes.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

A facile strategy to fabricate a lignin-based thermoset alternative to formaldehyde-based wood adhesives

The utilization of sustainable lignin to synthesize wood adhesives has attracted increasing attention in recent years. However, the facile fabrication of strong and environmentally friendly lignin-based adhesives with a high lignin content remains a significant challenge. In this study, we developed a formaldehyde-free wood adhesive system by combining alkali lignin and poly(propylene glycol) bis(2-aminopropyl ether). The process of producing lignin-based adhesives involves a simple mixing of wood flour, lignin, and a commercially available crosslinker (polyetherimide), followed by direct hot-pressing into particleboards. The lignin-based adhesive showed a high biomass content of 75 wt% (crosslinker accounting for 25 wt%) and the internal bonding strength of the formaldehyde-free and non-toxic particleboards was 1.42 MPa, outperforming many other bio-based adhesives. In conclusion, the study demonstrates a new and facile strategy to synthesize a lignin-based thermoset that is readily and practically applicable as an adhesive to fabricate high-performance, high lignin content, and formaldehyde-free wood products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

A large enhancement of ionic conductivity in SrCoO 2.5 controlled by isostructural phase transition and negative linear compressibility

The exploration of next-generation materials and the underlying mechanisms for high ionic conductivity have been the mainstay of the study in the solid state ionic field, but with limited success. Here, we performed closely integrated in situ high-pressure structural and electronic characterizations on SrCoO 2.5 , a typical material for solid fuel cell application. We discovered that the activation energy for ionic transport decreased by approximately 47% at 13.6 GPa upon compression, demonstrating a large enhancement of conductivity. Such a desired functional behavior is strongly interlinked with the pressure-driven isostructural phase transition at which negative linear compressibility occurs along c-lattice, weakening the interaction between Co and O atoms and then enhancing the ionic diffusion. Our results provide fundamental insight of the solid ionic mechanism and materials-by-design for future high-performance oxides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Software Defined Architectures for Portability and Performance

The Software Defined Architectures for Portability and Performance (SODAPOP) project developed a co-design framework to partition and map converged applications on specialized heterogeneous architectures. We started from key domain applications that combine scientific simulation with data analytics and machine learning as drivers to integrate our framework. The framework includes high-level compilers that interfaces with high-level programming frameworks, domain-specific optimization passes, and hardware-oriented optimizations. The framework leverages hardware generators to enable specialization and facilitate exploration of custom system designs.

97 MATHEMATICS AND COMPUTING↗