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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

High-Fidelity Simulation of Flow-Induced Vibrations in Helical Steam Generators for Small Modular Reactors

Flow-induced vibration (FIV) is a widespread problem in energy systems as they rely on fluid movement for energy conversion. Vibrating structures may be damaged as fatigue or wear occur. Given the importance of reliable components in the nuclear industry, FIV has long been a major concern in the safety and operation of nuclear reactors. In particular, nuclear fuel rods and steam generators have been known to suffer from FIV and related failures. In this paper we discuss the use of the computational fluid dynamics code Nek5000 coupled to the structural code Diablo to simulate the flow in helical coil heat exchangers and associated FIV. In particular, one-way coupled calculations are performed, where pressure and tractions data are loaded into the structural model. The main focus of this paper is on validation of this capability. Fluid-only Nek5000 large eddy simulations are first compared against dedicated high-resolution experiments. Then, one-way coupled calculations are performed with Nek5000 and Diablo for two data sets that provide FIV data for validation. These calculations were aimed at simulating available legacy FIV experiments in helical steam generators in the turbulent buffeting regime. In this regime one-way coupling is judged sufficient since the pressure loads do not cause substantial displacements. It is also the most common source of vibration in helical steam generators at the low flows expected in integral pressurized water reactors. We discuss validation of two-way coupled experiments and benchmarks toward the simulation of fluid elastic instability. We briefly discuss the application of these methods to grid-to-rod fretting.

Flow-Induced Vibration↗
DOE OSTI2018

A Review of Interface Microstructures in Electronic Packaging Applications: Soldering Technology

Here, this report examines the role of interfaces in electronic packaging applications with the focus placed on soldering technology. Materials and processes are described with respect to their roles on the performance and reliability of associated interfaces. The discussion will also include interface microstructures created by coatings and finishes that are frequently used in packaging applications. Numerous examples are cited to illustrate the importance of interfaces in physical and mechanical metallurgy as well as the engineering function of interconnections. Regardless of the specific application, interfaces are non-equilibrium structures , which has important ramifications for the long-term reliability of electronic packaging.

42 ENGINEERING↗
DOE OSTI2024

On-demand nanoengineering of in-plane ferroelectric topologies

Hierarchical assemblies of ferroelectric nanodomains, so-called super-domains, can exhibit exotic morphologies that lead to distinct behaviours. Controlling these super-domains reliably is critical for realizing states with desired functional properties. Here we reveal the super-switching mechanism by using a biased atomic force microscopy tip, that is, the switching of the in-plane super-domains, of a model ferroelectric Pb 0.6 Sr 0.4 TiO 3 . We demonstrate that the writing process is dominated by a super-domain nucleation and stabilization process. A complex scanning-probe trajectory enables on-demand formation of intricate centre-divergent, centre-convergent and flux-closure polar structures. Correlative piezoresponse force microscopy and optical spectroscopy confirm the topological nature and tunability of the emergent structures. The precise and versatile nanolithography in a ferroic material and the stability of the generated structures, also validated by phase-field modelling, suggests potential for reliable multi-state nanodevice architectures and, thereby, an alternative route for the creation of tunable topological structures for applications in neuromorphic circuits.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Soil Aggregate Microbial Communities: Towards Understanding Microbiome Interactions at Biologically Relevant Scales

Soils contain a tangle of minerals, water, nutrients, gases, plant roots, decaying organic matter, and microorganisms which work together to cycle nutrients and support terrestrial plant growth. Most soil microorganisms live in periodically interconnected communities closely associated with soil aggregates, i.e., small (<2 mm), strongly bound clusters of minerals and organic carbon that persist through mechanical disruptions and wetting events. Their spatial structure is important for biogeochemical cycling, and we cannot reliably predict soil biological activities and variability by studying bulk soils alone. To fully understand the biogeochemical processes at work in soils, it is necessary to understand the micrometer-scale interactions that occur between soil particles and their microbial inhabitants. Here, we review the current state of knowledge regarding soil aggregate microbial communities and identify areas of opportunity to study soil ecosystems at a scale relevant to individual cells. We present a framework for understanding aggregate communities as “microbial villages” that are periodically connected through wetting events, allowing for the transfer of genetic material, metabolites, and viruses. Here, we describe both top-down (whole community) and bottom-up (reductionist) strategies for studying these communities. Understanding this requires combining “model system” approaches (e.g., developing mock community artificial aggregates), field observations of natural communities, and broader study of community interactions to include understudied community members, like viruses. Initial studies suggest that aggregate-based approaches are a critical next step for developing a predictive understanding of how geochemical and community interactions govern microbial community structure and nutrient cycling in soil.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

A novel hardmask-to-substrate pattern transfer method for creating 3D, multi-level, hierarchical, high aspect-ratio structures for applications in microfluidics and cooling technologies

Abstract This letter solves a major hurdle that mars photolithography-based fabrication of micro-mesoscale structures in silicon. Conventional photolithography is usually performed on smooth, flat wafer surfaces to lay a 2D design and subsequently etch it to create single-level features. It is, however, unable to process non-flat surfaces or already etched wafers and create more than one level in the structure. In this study, we have described a novel cleanroom-based process flow that allows for easy creation of such multi-level, hierarchical 3D structures in a substrate. This is achieved by introducing an ultra-thin sacrificial silicon dioxide hardmask layer on the substrate which is first 3D patterned via multiple rounds of lithography. This 3D pattern is then scaled vertically by a factor of 200–300 and transferred to the substrate underneath via a single shot deep etching step. The proposed method is also easily characterizable—using features of different topographies and dimensions, the etch rates and selectivities were quantified; this characterization information was later used while fabricating specific target structures. Furthermore, this study comprehensively compares the novel pattern transfer technique to already existing methods of creating multi-level structures, like grayscale lithography and chip stacking. The proposed process was found to be cheaper, faster, and easier to standardize compared to other methods—this made the overall process more reliable and repeatable. We hope it will encourage more research into hybrid structures that hold the key to dramatic performance improvements in several micro-mesoscale devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

LiPON and NaPON glasses: A study of the ammonolysis of lithium and sodium metaphosphate melts

Metaphosphate glasses such as LiPO 3 and NaPO 3 are known to incorporate nitrogen in the molten state under NH 3 flow to form (Li/Na)PON glasses through the reaction: (Li/Na)PO 3 + x NH 3 → (Li/Na)PO 3–(3 x /2) N x + (3 x /2)H 2 O, by partially replacing two-coordinated oxygen with two- and three-coordinated nitrogen. After nitridation, the glasses exhibit improved properties such as increased working range, chemical durability, and ionic conductivity. In this study, LiPO 3 and NaPO 3 glasses were prepared by the conventional melting and casting method and used as base glasses for the ammonolysis procedure. The nitridation processes were carried out by remelting the base glasses at temperatures up to 780°C, under a constant NH 3 flow. The effects on the nitrogen content in the resulting (Li/Na)PON glasses caused by different processing times and masses of powder and/or bulk materials were investigated. Nitridation was successfully confirmed by CNHS chemical analyses, Raman spectroscopy, and Differential Scanning Calorimetry. Mass loss measurements after the ammonolysis process and Raman spectroscopy were used to quantify the nitrogen content into the glass structure. A new approach using a specific Raman normalization, (P–N<)/(O–P–O) sym , has been demonstrated as a reliable, simple, and fast way to determine the amounts of N incorporated to metaphosphate glass structures.

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

Dominant Energy Carrier Transitions and Thermal Anisotropy in Epitaxial Iridium Thin Films

High aspect ratio metal nanostructures are commonly found in a broad range of applications such as electronic compute structures and sensing. The self-heating and elevated temperatures in these structures, however, pose a significant bottleneck to both the reliability and clock frequencies of modern electronic devices. Any notable progress in energy efficiency and speed requires fundamental and tunable thermal transport mechanisms in nanostructured metals. Here, in this work, time-domain thermoreflectance is used to expose cross-plane quasi-ballistic transport in epitaxially grown metallic Ir(001) interposed between Al and MgO(001). Thermal conductivities ranges from roughly 65 (96 in-plane) to 119 (122 in-plane) W m -1 K -1 for 25.5–133.0 nm films, respectively. Further, low defects afforded by epitaxial growth are suspected to allow the observation of electron–phonon coupling effects in sub-20 nm metals with traditionally electron-mediated thermal transport. Via combined electro-thermal measurements and phenomenological modeling, the transition is revealed between three modes of cross-plane heat conduction across different thicknesses and an interplay among them: electron dominant, phonon dominant, and electron–phonon energy conversion dominant. The results substantiate unexplored modes of heat transport in nanostructured metals, the insights of which can be used to develop electro-thermal solutions for a host of modern microelectronic devices and sensing structures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Long-term thermal aging behavior and strength reduction in a laser powder bed fusion 316H stainless steel

The long-term thermal stability of structural alloys is essential for ensuring the safe and reliable operation of nuclear reactors and other power plants. While extensive research has explored the effects of thermal aging on conventional stainless steels, the behavior of additively manufactured (AM) alloys remains less understood. This study examines the thermal aging response of laser powder bed fusion (LPBF) 316H stainless steel (SS) at temperatures ranging from 550 °C to 750 °C over durations of up to 10,000 h (approximately 1.14 years). Advanced characterization techniques, including electron microscopy and synchrotron X-ray diffraction, were used to investigate dislocation recovery and phase evolution. Based on these findings, a time-temperature-precipitation (TTP) diagram was developed for LPBF 316H SS, revealing a 10- to100-fold acceleration in precipitation kinetics compared to wrought 316H SS. A physics-informed model was calibrated using the short-term experimental data, enabling predictions of average precipitate sizes, volume fractions of M 23 C 6 and Laves phases, and changes in molybdenum solute concentration for aging up to 1 × 10⁶ h (114 years). These microstructural insights were further utilized to estimate yield strength and extrapolate strength reduction factors over the extended aging period. Despite the accelerated aging kinetics, LPBF 316H SS demonstrated superior yield strength retention compared to its wrought counterpart. In conclusion, this study establishes a framework for evaluating long-term performance using short-term experimental data and supports the accelerated qualification of AM materials for high-temperature structural applications.

Laser powder bed fusion↗
DOE OSTI2021

Halo effective field theory analysis of one-neutron knockout reactions of Be 11 and C 15

Background: One-nucleon knockout reactions provide insightful information on the single-particle structure of nuclei. When applied to one-neutron halo nuclei, they are purely peripheral, suggesting that they could be properly modeled by describing the projectile within a halo effective field theory (halo-EFT). Purpose: We reanalyze the one-neutron knockout measurements of 11 Be and 15 C —both one-neutron halo nuclei—on beryllium at about 60 MeV/nucleon. We consider halo-EFT descriptions of these nuclei which already provide excellent agreement with breakup and transfer data. Method: Here we include a halo-EFT description of the projectile within an eikonal-based model of the reaction and compare its outcome to existing data. Results: Excellent agreement with experiment is found for both nuclei. The asymptotic normalization coefficients inferred from this comparison confirm predictions from ab initio nuclear-structure calculations and values deduced from transfer data. Conclusions: Halo-EFT can be reliably used to analyze one-neutron knockout reactions measured for halo nuclei and test predictions from state-of-the-art nuclear structure models on these experimental data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Massachusetts Large Blade Test Facility Final Report

Project Objective: The Massachusetts Clean Energy Center (CEC) will design, construct, and ultimately have responsibility for the operation of the Large Wind Turbine Blade Test Facility, which is an advanced blade testing facility capable of testing wind turbine blades up to at least 90 meters in length on three test stands. Background: Wind turbine blade testing is required to meet international design standards, and is a critical factor in maintaining high levels of reliability and mitigating the technical and financial risk of deploying massproduced wind turbine models. Testing is also needed to identify specific blade design issues that may contribute to reduced wind turbine reliability and performance. Testing is also required to optimize aerodynamics, structural performance, encourage new technologies and materials development making wind even more competitive. The objective of this project is to accelerate the design and construction of a large wind blade testing facility capable of testing blades with minimum queue times at a reasonable cost. This testing facility will encourage and provide the opportunity for the U.S wind industry to conduct more rigorous testing of blades to improve wind turbine reliability.

17 WIND ENERGY↗
DOE OSTI2016

The equation of state of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one determined via in-situ optical microscopy and interferometry measurements

Quasi-hydrostatic high-pressure equations of state (EOS) are typically determined, for crystalline solids, by measuring unit-cell volumes using x-ray diffraction (XRD) techniques. However, when characterizing low-symmetry materials with large unit cells, conventional XRD approaches may become problematic. To overcome this issue, we examined the utility of a “direct” approach toward determining high pressure material volume by measuring surface area and sample thickness using optical microscopy and interferometry (OMI), respectively. We have validated this experimental approach by comparing results obtained for 2,4,6-triamino-1,3,5-trinitrobenzene TATB with an EOS determined from synchrotron XRD measurements; and, a good match is observed. We have measured the high pressure EOS of 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (α-NTO) up to 28 GPa. No high-pressure XRD EOS data have been published on α-NTO, probably due to its complex crystal structure. The results of this study suggest that OMI is a reliable and versatile alternative for determining EOSs, especially when conventional methodologies are impractical.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Properties of reactive oxygen species by quantum Monte Carlo

The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of chemistry, biology, and atmospheric science. Nevertheless, the electronic structure of such species is a challenge for ab initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution, and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular, we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as N{sup 3} − N{sup 4}, where N is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Scheduling and Pricing for Expected Ramp Capability in Real-Time Power Markets

Higher variable renewable generation penetrations are occurring throughout the world on different power systems. These resources increase the variability and uncertainty on the system which must be accommodated by an increase in the flexibility of the system resources in order to maintain reliability. Many scheduling strategies have been discussed and introduced to ensure that this flexibility is available at multiple timescales. To meet variability, that is, the expected changes in system conditions, two recent strategies have been introduced: time-coupled multi-period market clearing models and the incorporation of ramp capability constraints. To appropriately evaluate these methods, it is important to assess both efficiency and reliability. But it is also important to assess the incentive structure to ensure that resources asked to perform in different ways have the proper incentives to follow these directions, which is a step often ignored in simulation studies. Here we find that there are advantages and disadvantages to both approaches. We also find that look-ahead horizon length in multi-period market models can impact incentives. This paper proposes scheduling and pricing methods that ensure expected ramps are met reliably, efficiently, and with associated prices based on true marginal costs that incentivize resources to do as directed by the market. Case studies show improvements of the new method.

25 ENERGY STORAGE↗
DOE OSTI2014

Structure of Cu{sub 64.5}Zr{sub 35.5} metallic glass by reverse Monte Carlo simulations

Reverse Monte Carlo simulations (RMC) have been widely used to generate three dimensional (3D) atomistic models for glass systems. To examine the reliability of the method for metallic glass, we use RMC to predict the atomic configurations of a “known” structure from molecular dynamics (MD) simulations, and then compare the structure obtained from the RMC with the target structure from MD. We show that when the structure factors and partial pair correlation functions from the MD simulations are used as inputs for RMC simulations, the 3D atomistic structure of the glass obtained from the RMC gives the short- and medium-range order in good agreement with those from the target structure by the MD simulation. These results suggest that 3D atomistic structure model of the metallic glass alloys can be reasonably well reproduced by RMC method with a proper choice of input constraints.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Functional protein mining with conformal guarantees

Molecular structure prediction and homology detection offer promising paths to discovering protein function and evolutionary relationships. However, current approaches lack statistical reliability assurances, limiting their practical utility for selecting proteins for further experimental and in-silico characterization. To address this challenge, we introduce a statistically principled approach to protein search leveraging principles from conformal prediction, offering a framework that ensures statistical guarantees with user-specified risk and provides calibrated probabilities (rather than raw ML scores) for any protein search model. Our method (1) lets users select many biologically-relevant loss metrics (i.e. false discovery rate) and assigns reliable functional probabilities for annotating genes of unknown function; (2) achieves state-of-the-art performance in enzyme classification without training new models; and (3) robustly and rapidly pre-filters proteins for computationally intensive structural alignment algorithms. Our framework enhances the reliability of protein homology detection and enables the discovery of uncharacterized proteins with likely desirable functional properties.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

The Plug-and-Play Electricity Era: Interoperability to Integrate Anything, Anywhere, Anytime

The advent of the information age continues to transform the mechanics of integrating electric power devices and systems from coordinated operations based purely on the physics of electric power engineering to an increasing blend of power with information and communications technology engineering. Integrating electric system components is not just about attaching electric power wires but requires the connection of computer-based automation systems and their associated sensing and communications equipment. The architectural impacts are significant. Well-considered and commonly held concepts, principles, and organizational structures have been emerging to address the complexity of the integrated operational challenges that drives our society to expect more flexibility in configuring the electric power system, while simultaneously achieving greater efficiency, reliability, and resilience. Architectural concepts such as modularity and composability contribute to forming structures that enable the connection of power system equipment characterized by clearly-defined interfaces that consist of physical connections and cyber connections. Overall, the result of successful integration of the components of the electric power system is interoperation; the discipline that drives the integration to be simple and reliable is the topic of interoperability.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2018

Photovoltaic Power Supply Unit for the Basic Stations of Cellular Companies

The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered.

14 SOLAR ENERGY↗
DOE OSTI2012

Band gap tuning and optical absorption in type-II InAs/GaSb mid infrared short period superlattices: 14 bands K Dot-Operator p study

The MBE growth of short-period InAs/GaSb type-II superlattice structures, varied around 20.5 A InAs/24 A GaSb were [J. Applied physics, 96, 2580 (2004)] carried out by Haugan et al. These SLs were designed to produce devices with an optimum mid-infrared photoresponse and a sharpest photoresponse cutoff. We have used a realistic and reliable 14-band k.p formalism description of the superlattice electronic band structure to calculate the absorption coefficient in such short-period InAs/GaSb type-II superlattices. The parameters for this formalism are known from fitting to independent experiments for the bulk materials. The band-gap energies are obtained without any fitting parameters, and are in good agreement with experimental data.

36 MATERIALS SCIENCE↗