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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Convergence and Quantum Advantage of Trotterized MERA for Strongly-Correlated Systems

Strongly-correlated quantum many-body systems are difficult to study and simulate classically. We recently proposed a variational quantum eigensolver (VQE) based on the multiscale entanglement renormalization ansatz (MERA) with tensors constrained to certain Trotter circuits. Here, we determine the scaling of computation costs for various critical spin chains which substantiates a polynomial quantum advantage in comparison to classical MERA simulations based on exact energy gradients or variational Monte Carlo. Algorithmic phase diagrams suggest an even greater separation for higher-dimensional systems. Hence, the Trotterized MERA VQE is a promising route for the efficient investigation of strongly-correlated quantum many-body systems on quantum computers. Furthermore, we show how the convergence can be substantially improved by building up the MERA layer by layer in the initialization stage and by scanning through the phase diagram during optimization. For the Trotter circuits being composed of single-qubit and two-qubit rotations, it is experimentally advantageous to have small rotation angles. We find that the average angle amplitude can be reduced considerably with negligible effect on the energy accuracy. Benchmark simulations suggest that the structure of the Trotter circuits for the TMERA tensors is not decisive; in particular, brick-wall circuits and parallel random-pair circuits yield very similar energy accuracies.

Miao, Qiang [Duke Quantum Center, Duke University,↗
DOE OSTI2014

High-quality II-VI films grown on amorphous substrates using tunable tetradymite templates

We demonstrate the growth of highly oriented CdSe and ZnTe films at ~300 °C on amorphous substrates such as glass and flexible polyimide using ultrathin tetradymite buffer layers composed of Sb x Bi 2-x Te 3 alloys lattice-matched to the film overgrowth. This leads to significant improvement of the crystallinity, roughness, grain size, and pit density of the II-VI overlayer along with enhancement of the optoelectronic properties. For example, photoluminescence emission is observed at ~1.74 eV for optimized CdSe films, the same as in a single crystal reference. An in-plane carrier diffusion length of ~500 nm is inferred from transient optical data. The use of tetradymite buffer layers to control II-VI compound deposition on non-crystalline substrates is a promising route for large area optoelectronic applications such as photovoltaic, light-emission, or infrared detector devices.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Group-Additivity–Embedded Multiscale Modeling for Electric Field-Enhanced Nanocatalysis

Elucidating structure-performance relationships remains a central challenge in field-enhanced catalysis, where nanoparticles exhibit nonuniform surface sites with site-dependent responses to electric fields. Low-coordination sites (edges, corners, and tips) are particularly electric field-sensitive (EF), leading to nonuniform charge distribution, adsorption energies, and catalytic activity. Here, using ammonia decomposition on a ruthenium cluster as a model system, we develop a transferable multiscale framework integrating density functional theory, group additivity (GA), Brønsted-Evans-Polanyi scaling, and microkinetic modeling to predict EF-dependent activity across nonuniform cluster sites. Across sites and fields, the nitrogen adsorption energy (E N ) emerges as the governing descriptor, yielding robust volcano relationships whose optimum shifts systematically with field: negative fields strengthen N binding via electron accumulation, while positive fields weaken N binding via charge depletion, moving the optimal E N toward weaker binding. Microkinetic analysis shows that N≡N bond formation remains the key kinetic bottleneck over most conditions; positive fields lower the effective barrier and, critically, increase the fraction of near-optimal active sites, leading to a net enhancement in overall activity relative to zero-field and negative-field cases. By capturing EF- and site-dependent energetics with high accuracy and low computational cost, this GA-embedded multi-scale simulation workflow provides a physically interpretable route to predict and design field-enhanced nanocatalysis.

ammonia decomposition↗
DOE OSTI2023

Carbon optimized production of 3-hydroxypropionic acid in the Agile BioFoundry organism Rhodosporidium toruloides

The modern global economy relies heavily on carbon-based products that are derived from petroleum, which presents sustainability, resource management, and greenhouse gas exacerbated climate change challenges. Due to these challenges, there is the need for a global industrial transition towards green and sustainable production. Microbial production of valuable chemicals from renewable biomass represents one promising route. However, high-volume low-value products such as commodity chemicals are still difficult to make profitable. One fundamental bottleneck is a waste of more than 1/3 of the feedstock carbon as CO 2 in the fermentation process. Here the project focuses on fundamentally reconfiguring the metabolism to reduce CO 2 loss in central metabolic pathways thereby also improving bioproduct yields. Here we present technologies to prevent CO 2 loss and balance reducing equivalents within the cell to enable complete conversion of glucose from renewable feedstocks into bioproducts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Optimizing stadium evacuation by integrating geocomputation and affordance theory

Football is culturally and economically important in the United States, and football stadiums are part of the country's critical infrastructure, thus receiving government protection against hazard events. In this project, an agent-based evacuation model was implemented to optimize evacuation time from The University of Southern Mississippi's M.M. Roberts Stadium (football) by accounting for evacuees’ age, gender, physical fitness, alcohol consumption, and prior experience with hazard events. The findings revealed that (i) the age and gender of an individual impact his/her locomotion speed and (ii) evacuation route choice is influenced by evacuees’ perception of its safety and effectiveness. The estimated evacuation times for all evacuees to exit only the stadium and the stadium plus the surrounding campus were 20.82 and 165.01 minutes, respectively. Both of these times were shorter than the evacuation times determined by models employing location-unspecific locomotion speeds. One-way analysis of variance revealed that there were statistically significant differences between use of location-specific and location-unspecific within-stadium evacuation times (p ≤ 0.001 with α = 0.05). These results suggest that using local data is vital to accurately estimate evacuation time.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2016

Fabrication of UN microsphere kernels for Fully Ceramic Microencapsulated fuel

Fully Ceramic Microencapsulated (FCM) fuel is of interest to the U.S. Department of Energy's Fuel Cycle Research and Development program as an Accident Tolerant Fuel (ATF). The FCM design uses a TRISO (Tri-Structural Isotropic) particle with a ZrO{sub 2} surrogate kernel, embedded in a dense SiC matrix. TRISO technology, originally developed for High Temperature Gas Reactors, has an established high level of performance retaining fission products and the SiC matrix of an FCM compact shows good steam oxidation behavior. This work reports on a fabrication route for producing dense UN microspheres used as the kernel of the TRISO particles in FCM fuel. The UN microspheres are of high purity and density with enough porosity to accommodate volatile fission products. Increasing the density is nevertheless of interest potentially allowing for an additional adjustable property for optimizing the fuel kernel and TRISO particle characteristics. Current work is focused on investigating the effect of a feedstock microstructure on final product density. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Cooling arbitrary near-critical systems using hyperbolic quenches

We describe a quench protocol that allows the rapid preparation of ground states of arbitrary interacting conformal field theories in 1+1 dimensions. We start from the ground state of a related gapped relativistic quantum field theory and consider sudden quenches along the spacelike trajectories t 2 – x 2 = $T$ $^{2}_{0}$ (parameterized by T 0 ) to a conformal field theory. Using only arguments of symmetry and conformal invariance, we show that the post-quench stress-energy tensor of the conformal field theory is uniquely constrained up to an overall scaling factor. Crucially, the geometry of the quench necessitates that the system approach the vacuum energy density over all space except the singular lines x = ±t. Here, the above arguments are verified using an exact treatment of the quench for the Gaussian scalar field theory (equivalently the Luttinger liquid), and numerically for the quantum O(N) model in the large-N limit. Additionally, for the Gaussian theory, we find in fact that even when starting from certain excited states, the quench conserves entropy, and is thus also suitable for rapidly preparing excited states. Our methods serve as a fast, alternative route to reservoir-based cooling to prepare quantum states of interest.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Developing reactors for electrifying bio-methanation: a perspective from bio-electrochemistry

The integration of microbial synthesis with renewable electricity is an emerging route for both CO 2 utilization and seasonal energy storage in the form of stored bio-electrofuels. The major benefits of electrifying bioreactors include: using highly selective bio-catalysts for CO 2 conversion under mild reaction conditions; decoupling the production of more facile electrochemical intermediates, such as hydrogen, at the electrode from the production of bio-catalyzed multi-electron and/or carbon products, such as methane or acetate; using microbes as robust and self-regenerating catalysts enabling higher efficiency and durability in CO 2 conversion systems compared to inorganic catalysis. In this Perspective, we propose research aimed at developing electro-bioreactor components that will increase the productivity of the reactor while maintaining high energy efficiency and biocompatible reaction conditions to fully realize the benefits of electrified bioreactors. Furthermore, these developments include: flow reactors with tailored 3D electrodes to optimally use the reactor volume, electrocatalysts designed for peak performance in neutral pH electrolytes, high conductivity microbial media, and new membrane separator materials with high ion conductivity and low gas permeability. Production of methane via a hybrid electrical-biological approach is taken as a case study to motivate these developments. Finally, an iterative design–manufacture–test cycle, enabled by additive manufacturing and 3D printing technologies, is proposed to rapidly prototype components prior to large-scale manufacturing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Extended Ladder‐Type Benzo[ k ]tetraphene‐Derived Oligomers

Abstract Well‐defined, fused‐ring aromatic oligomers represent promising candidates for the fundamental understanding and application of advanced carbon‐rich materials, though bottom‐up synthesis and structure–property correlation of these compounds remain challenging. In this work, an efficient synthetic route was employed to construct extended benzo[ k ]tetraphene‐derived oligomers with up to 13 fused rings. The molecular and electronic structures of these compounds were clearly elucidated. Precise correlation of molecular sizes and crystallization dynamics was established, thus demonstrating the pivotal balance between intermolecular interaction and molecular mobility for optimized processing of highly ordered solids of these extended conjugated molecules.

Lee, Jongbok↗
DOE OSTI2013

Thermodynamic studies of CaLaFe₁₁O₁₉(s)

Thermodynamic studies on CaLaFe₁₁O₁₉(s) were carried out using Knudsen effusion mass spectrometry and calorimetry, viz. differential scanning calorimetry and high temperature oxide melt solution calorimetry. Standard molar Gibbs free energy of formation (Δ{sub f}G⁰{sub m}), enthalpy of formation and heat capacity (C⁰{sub ₚ,m}) of the compound were calculated as a function of temperature for the first time. C⁰{sub ₚ,m}(CaLaFe₁₁O₁₉) was determined and used for second law analysis, from which enthalpy and entropy of formation of the compound were calculated and the respective values are: Δ{sub f}H⁰{sub m}(298.15 K)/kJ mol⁻¹=-6057(±8) and S⁰{sub m}(298.15 K)/J K⁻¹ mol⁻¹=427(±5). Δ{sub f}H⁰{sub m}(298.15 K)/kJ mol⁻¹: -6055(±6) was also calculated using oxide melt solution calorimetry, which is in close agreement with the second law value. A heat capacity anomaly was also observed at T=684 K. A table of thermodynamic data from 298.15 K to 1000 K for CaLaFe₁₁O₁₉(s) was also constructed to represent an optimized set of data. - graphical abstract: Variation of standard molar heat capacities of CaLaF₁₁O₁₉(s) and MFe₁₂O₁₉(s) (M=Sr, Ba and Pb) as a function of temperature. Highlights: • Thermodynamic studies on CaLaFe₁₁O₁₉(s) were performed using KEQMS and solution calorimetry. • It was synthesized using gel combustion route and characterized by XRD technique. • The compound is magnetic in nature and shows a heat capacity anomaly at 684 K. • Thermodynamic table was constructed from 298 K to 1000 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Superconductor-in-an-Hour: Spark Plasma Synthesis of Co- and Ni-Doped BaFe 2 As 2

In this work, BaFe 2 As 2 superconductors doped with Co or Ni were synthesized by heat treatment of the reactive BaH 2 precursor and elemental Fe, Co, Ni, and As in a sealed niobium container. The hydride route provides better mixing of the starting materials, resulting in faster preparation of the target phases. The hydrogen gas evolved during sintering facilitates the preparation of the oxygen-free powders. Using powder X-ray diffraction (PXRD), including low-temperature synchrotron PXRD, it was shown that this route leads to successful doping of the Co (Ni) dopant and that the actual dopant content in the produced powdered samples of BaFe 2– x Co x As 2 (0 ≤ x ≤ 0.4) and BaFe 2– x Ni x As 2 (0 ≤ x ≤ 0.18) is close to the nominal content. The optimally doped samples of BaFe 2– x Co x As 2 and BaFe 2– x Ni x As 2 exhibit bulk superconducting properties. The highest T c for the Co-doped sample is 24 K when x = 0.15–0.175 and 21 K for the Ni-doped sample when x ~ 0.1. The reaction mechanism between the BaH 2 hydride precursor and elemental Fe and As was studied by operando high-temperature synchrotron PXRD. The formation of the target BaFe 2 As 2 phase occurs at the relatively low temperature of 785 K with binary iron arsenide (FeAs) being an intermediate product. Finally, the in situ combined synthesis and sintering of the intimately mixed BaH 2 and Fe, Co, and As was performed inside the spark plasma sintering apparatus to obtain compact pellets of the BaFe 2– x Co x As 2 superconductors. A higher sintering temperature (>873 K) is needed to ensure a homogeneous Co dopant distribution and, thus, the abrupt superconducting transitions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Two-step spin-coating of vacancy-ordered double perovskites enables growth of thin films for electronic devices

Vacancy-ordered double perovskites (VODPs), such as Cs 2 TeX 6 (X = Cl, Br, I), are lead-free alternatives to conventional metal-halide perovskites (MHPs). One limitation of VODPs is the lack of processes to form thin films relevant for physical characterization and electronic devices. A two-step spin-coating method was developed for synthesizing high-quality films of Cs 2 TeBr 6 . Independently depositing CsBr and TeBr 4 enables high precursor concentrations and control over crystallization kinetics. By optimizing the spin-coating parameters, conversion of precursors to phase pure films was observed using structural and surface characterization methods. The growth of mixed-halide systems was investigated using alternative salts including CsCl and CsI. The formation of halide alloys was found to depend on the existence of routes to byproducts. Lastly, single carrier diodes of Cs2TeBr6 were designed following valence band characterization with photoelectron spectroscopy. Temperature-dependent space-charge-limited current measurements revealed that transport occurs by hopping and the hole mobility is 3.2 × 10 −5 cm 2 V −1 s −1 near room temperature. As a result, the insights from the 2-step procedure provide a pathway towards making semiconducting devices from VODPs.

Kuklinski, Owen [University of California, Santa B↗
DOE OSTI2017

Ultrasound-assisted facile synthesis of a new tantalum(V) metal-organic framework nanostructure: Design, characterization, systematic study, and CO{sub 2} adsorption performance

This work presents a fast route for the preparation of a new Ta(V) metal-organic framework nanostructure with high surface area, significant porosity, and small size distribution. X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), energy dispersive spectrometer (EDS), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyser, and Brunauer-Emmett-Teller (BET) surface area analysis were applied to characterize the synthesized product. Moreover, the influences of ultrasonic irradiation including temperature, time, and power on different features of the final products were systematically studied using 2{sup k-1} factorial design experiments, and the response surface optimization was used for determining the best welding parameter combination. The results obtained from analyses of variances showed that ultrasonic parameters affected the size distribution, thermal behaviour, and surface area of Ta-MOF samples. Based on response surface methodology, Ta-MOF could be obtained with mean diameter of 55 nm, thermal stability of 228 °C, and high surface area of 2100 m{sup 2}/g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO{sub 2} adsorption. - Graphical abstract: A facile route was used for fabrication of a new metal -organic framework based on tantalum nanostructures that have high surface area, considerable porosity, homogenous morphology, and small size distribution.

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

Neural Network-Based Electric Vehicle Range Prediction for Smart Charging Optimization

Range prediction is a standard feature in most modern road vehicles, allowing drivers to make informed decisions about when to refuel. Most vehicles make range predictions through data- or model-driven means, monitoring the average fuel consumption rate or using a tuned vehicle model to predict fuel consumption. The uncertainty of future driving conditions makes the range prediction problem challenging, particularly for less pervasive battery electric vehicles (BEV). Most contemporary machine learning-based methods attempt to forecast the battery SOC discharge profile to predict vehicle range. In this work, we propose a novel approach using two recurrent neural networks (RNNs) to predict the remaining range of BEVs and the minimum charge required to safely complete a trip. Each RNN has two outputs that can be used for statistical analysis to account for uncertainties; the first loss function leads to mean and variance estimation (MVE), while the second results in bounded interval estimation (BIE). These outputs of the proposed RNNs are then used to predict the probability of a vehicle completing a given trip without charging, or if charging is needed, the remaining range and minimum charging required to finish the trip with high probability. Training data was generated using a low-order physics model to estimate vehicle energy consumption from historical drive cycle data collected from medium-duty last-mile delivery vehicles. Here, the proposed method demonstrated high accuracy in the presence of day-to-day route variability, with the root-mean-square error (RMSE) below 6% for both RNN models.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Extended Ladder-Type Benzo[k]tetraphene-Derived Oligomers

Well-defined, fused-ring aromatic oligomers represent promising candidates for the fundamental understanding and application of advanced carbon-rich materials, though bottom-up synthesis and structure–property correlation of these compounds remain challenging. In this work, an efficient synthetic route was employed to construct extended benzo[k]tetraphene-derived oligomers with up to 13 fused rings. The molecular and electronic structures of these compounds were clearly elucidated. Precise correlation of molecular sizes and crystallization dynamics was established, thus demonstrating the pivotal balance between intermolecular interaction and molecular mobility for optimized processing of highly ordered solids of these extended conjugated molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Opportunities in full-stack design of low-overhead fault-tolerant quantum computation

Quantum error correction provides a route to realizing large-scale quantum computation but incurs substantial resource overheads. Here, in this work, we highlight recent advances that reduce these overheads by co-designing different levels of the computational stack, including algorithms, quantum-error-correction strategies and hardware architecture. We then discuss opportunities for further optimization such as leveraging flexible qubit connectivity and quantum low-density parity check codes. These strategies can bring useful quantum computation closer to reality as experiments advance in the coming years.

quantum information↗
DOE OSTI2022

Broadband polarization-entangled source for C+L-band flex-grid quantum networks

The rising demand for transmission capacity in optical networks has motivated steady interest in expansion beyond the standard C-band (1530–1565 nm) into the adjacent L-band (1565–1625 nm) for an approximate doubling of capacity in a single stroke. However, in the context of quantum networking, the L-band has yet to be fully leveraged with the suite of advanced tools for characterization and management available from classical lightwave communications. In this work, we demonstrate an ultrabroadband two-photon source integrating both C- and L-band wavelength-selective switches for complete control of spectral routing and allocation across 7.5 THz in a single setup. Polarization state tomography of all 150 pairs of 25-GHz-wide channels reveals an average fidelity of 0.98 and total distillable entanglement greater than 181 kebits/s. This source is explicitly designed for flex-grid optical networks and can facilitate optimal utilization of entanglement resources across the full C+L-band.

42 ENGINEERING↗
DOE OSTI2018

A Cascaded Multi-Rate Model Predictive Control and Reference Governor Approach for Real-Time Velocity Optimization in the Presence of Traffic

This paper presents a novel approach for ecological driving with distance keeping, where a long-horizon model predictive control (MPC) strategy for fuel consumption minimization is cascaded with a short-horizon reference governor for maintaining safe following distance. The control strategy developed in this work has been validated using a medium-fidelity proprietary Volvo model of a heavy-duty truck for three representative trucking routes. Results indicate the control strategy developed in this paper produces fuel savings of 5.11% - 6.17% when compared to the baseline.

33 ADVANCED PROPULSION SYSTEMS↗