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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 1,333 records · Page 74
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Finite element model for piles in liquefiable ground

This paper develops a three dimensional finite element modelling method for piles in liquefiable ground and applies it to the analysis of seismic pile responses. A unified plasticity model for large post-liquefaction shear deformation of sand provides the basis for the effective and efficient modelling of liquefiable ground. Special attention is dedicated towards the modelling of piles and soil-pile interface to accurately reflect the behaviour of piles. A staged modelling procedure is adopted to appropriately generate the initial conditions for the soil and piles and achieve hydrostatic pore pressure prior to seismic loading. Three centrifuge shaking table tests on single piles, both with and without pile cap and superstructure, in level and inclined liquefiable ground are conducted and simulated in validation and application of the proposed method. Further studies to investigate the effects of pile cap, lateral spreading, and non-liquefiable surface layer are undertaken numerically using the validated method. The results show these aforementioned factors to be influential in the dynamic and residual response of piles in liquefiable ground.

Centrifuge test↗
DOE OSTI2022

Survey of Surveys: I. The largest compilation of radial velocities for the Galaxy

In the present-day panorama of large spectroscopic surveys, the amount, diversity, and complexity of the available data continuously increase. The overarching goal of studying the formation and evolution of our Galaxy is hampered by the heterogeneity of instruments, selection functions, analysis methods, and measured quantities. Here, we present a comprehensive catalogue, the Survey of Surveys (SoS), built by homogeneously merging the radial velocity (RV) determinations of the largest ground-based spectroscopic surveys to date, such as APOGEE, GALAH, Gaia-ESO, RAVE, and LAMOST, using Gaia as a reference. This pilot study serves to prove the concept and to test the methodology that we plan to apply in the future to the stellar parameters and abundance ratios as well. We have devised a multi-staged procedure that includes: (i) the cross match between Gaia and the spectroscopic surveys using the official Gaia cross-match algorithm, (ii) the normalisation of uncertainties using repeated measurements or the three-cornered hat method, (iii) the cross calibration of the RVs as a function of the main parameters on which depend (magnitude, effective temperature, surface gravity, metallicity, and signal-to-noise ratio) to remove trends and zero point offsets, and (iv) the comparison with external high-resolution samples, such as the Gaia RV standards and the Geneva-Copenhagen survey, to validate the homogenisation procedure and to calibrate the RV zero-point of the SoS catalogue. We provide the largest homogenised RV catalogue to date, containing almost 11 million stars, of which about half come exclusively from Gaia and half in combination with the ground-based surveys. We estimate the accuracy of the RV zero-point to be about 0.16–0.31 km s –1 and the RV precision to be in the range 0.05–1.50 km s –1 depending on the type of star and on its survey provenance. We validate the SoS RVs with open clusters from a high resolution homogeneous samples and provide the systemic velocity of 55 individual open clusters. Additionally, we provide median RVs for 532 clusters recently discovered by Gaia data. The SoS is publicly available and ready to be applied to various research projects, such as the study of star clusters, Galactic archaeology, stellar streams, or the characterisation of planet-hosting stars, to name a few. We also plan to include survey updates and more data sources in future versions of the SoS.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

The DES Science Verification weak lensing shear catalogues

Here, we present weak lensing shear catalogues for 139 square degrees of data taken during the Science Verification (SV) time for the new Dark Energy Camera (DECam) being used for the Dark Energy Survey (DES). We also describe our object selection, point spread function estimation and shear measurement procedures using two independent shear pipelines, IM3SHAPE and NGMIX, which produce catalogues of 2.12 million and 3.44 million galaxies, respectively. Furthermore, we detail a set of null tests for the shear measurements and find that they pass the requirements for systematic errors at the level necessary for weak lensing science applications using the SV data. Finally, we discuss some of the planned algorithmic improvements that will be necessary to produce sufficiently accurate shear catalogues for the full 5-yr DES, which is expected to cover 5000 square degrees.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Evaluation Of Year 2020 IEEE RTS Generation Reliability Indices

A new IEEE Reliability Test System (2017 update) with wind and solar sources modeling 2020 has been created by NREL and posted on the GitHub RTS-GMLC repository. A simple procedure duplicates the 1979 RTS 'exact' indices and calculates indices for the 1996 RTS and the new 2020 Model RTS 'exact' indices. Extremely fast execution is realized by simply 'looking up' the exact LOLPs each hour from a COPT. Wind and solar are treated as hourly demand reducers. Computer program codes are included.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

Status and Challenges in the MQXFB Nb 3 Sn Quadrupoles for the HL-LHC

The inner triplet (or low-β) quadrupole magnets are among the components to be upgraded in LHC interaction regions for the HL-LHC project. The new quadrupole magnets, called MQXF, are based on Nb 3 Sn superconducting magnet technology, with a conductor peak field of 11.3 T. CERN is in charge of the fabrication of the MQXFB variant, the longest Nb 3 Sn accelerator magnets designed and manufactured up to now, with a magnetic length of 7.2 m. Two magnets, MQXFBP3 and MQXFB02, reached the HL-LHC project requirements. However, they still exhibited a limitation at 4.5 K with a phenomenology similar to the one observed on the first two prototypes. After improvements on the cold mass (longitudinal welding) and magnet assembly (elimination of overstress on the conductor during loading) procedures, a series of modifications were implemented in MQXFB03 at the level of the coil fabrication to address and/or reduce weaknesses in the coils. The magnet was tested and was the first to achieve performance requirements at both 1.9 K and 4.5 K, with no signs of conductor limitation at 4.5 K. MQXFB is now in the series production phase, with around 2/3 of the coils completed and half of the magnets assembled. We provide in this paper an overview of the MQXFB program, with a summary of the main recent achievements and an overall status of the fabrication.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

PCB-on-DBC GaN Power Module Design with High-Density Integration and Double-Sided Cooling

Lateral gallium nitride (GaN) high-electron-mobility transistors (HEMTs) present better electrical characteristics compared to silicon or silicon carbide devices such as high switching speed and low gate charge, but also present additional challenges on the module design. Here, this paper discusses a high-density GaN power module with double-sided cooling, low inductance, on-package decoupling capacitors, and integrated gate drivers. The GaN dies as well as the gate drive are sandwiched between the printed circuit board (PCB) and direct bonded copper (DBC) substrate to achieve compact loop and double-sided cooling effect. Design considerations and thermal performance are analyzed. A module assembly procedure is presented utilizing the layer-by-layer attachment process. Finally, a 2.7 cm x 1.8 cm half-bridge GaN power module is fabricated and tested, achieving a low power-loop inductance of 1.03 nH, and the overshoot voltage of the switching waveform is less than 5% under a 400-V/25-A double-pulse test. The thermal resistance is 0.32 K/W, verified by simulation and experimental results. The design and assembly process can be generalized and applied to high power applications to achieve high power density and high performance.

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

Mechanical Characterization Study of Sintered Silver Pastes Bonded in a Double-Lap Configuration

Sintered silver-based bonded interfaces are a critical enabling technology for high-temperature, compact, high-performance, and reliable wide-bandgap packages and components. High-pressure (~40 MPa) sintered silver interfaces have been implemented commercially, most notably the commercial products offered by Semikron. To reduce manufacturing complexity, there is significant industry interest in pressure-less sintered silver interfaces. To this end, current formulations of sintered silver paste are comprised of purely nano-sized silver particles or a combination of nano- and micro-sized silver particles/flakes. It is essential to quantify the mechanical properties and determine the reliability of these interfaces prior to use in automotive power electronics applications. In this paper, research efforts at the National Renewable Energy Laboratory, in collaboration with Virginia Polytechnic Institute and State University and an industry partner, in optimizing the synthesis procedure and mechanical characterization of sintered silver double-lap samples are described. These double-lap samples were synthesized using pressure-less sintering techniques. Shear testing was conducted at multiple temperatures and displacement rates on these samples sintered using two types of sintered sintered silver pastes, one of them consisting of nano-silver particles and the other a hybrid paste or a combination of nano- and micron-sized silver flakes, employed in a double-lap configuration. Maximum values of shear stress obtained from the characterization study are reported.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2017

Correction of Dual-PRF Doppler Velocity Outliers in the Presence of Aliasing

Abstract In Doppler weather radars, the presence of unfolding errors or outliers is a well-known quality issue for radial velocity fields estimated using the dual–pulse repetition frequency (PRF) technique. Postprocessing methods have been developed to correct dual-PRF outliers, but these need prior application of a dealiasing algorithm for an adequate correction. This paper presents an alternative procedure based on circular statistics that corrects dual-PRF errors in the presence of extended Nyquist aliasing. The correction potential of the proposed method is quantitatively tested by means of velocity field simulations and is exemplified in the application to real cases, including severe storm events. The comparison with two other existing correction methods indicates an improved performance in the correction of clustered outliers. The technique proposed is well suited for real-time applications requiring high-quality Doppler radar velocity fields, such as wind shear and mesocyclone detection algorithms, or assimilation in numerical weather prediction models.

58 GEOSCIENCES↗
DOE OSTI2022

Benchmark Analysis

Tremendous progress has been achieved in the development of land models and their inclusion in Earth system models (ESMs). However, we still have very limited knowledge on the performance skills of these land models. This chapter introduces benchmark analysis, which is a procedure to measure performance of models against a set of defined standards. The benchmark analysis includes: (1) defining targeted aspects of model performance to be evaluated; (2) testing model performance in comparison with a set of benchmarks; (3) measuring model performance skill through quantitative metrics; and (4) evaluating model performance and offering suggestions for future model improvement.

Luo, Yiqi↗
DOE OSTI2014

Direct Utilization of Coal Syngas in High Temperature Fuel Cells

This EPSCoR project had two primary goals: (i) to build infrastructure and work force at WVU to support long-term research in the area of fuel cells and related sciences; (ii) study effects of various impurities found in coal-syngas on performance of Solid Oxide Fuel Cells (SOFC). As detailed in this report the WVU research team has made significant accomplishments in both of these areas. What follows is a brief summary of these accomplishments: State-of-the-art test facilities and diagnostic tools have been built and put into use. These include cell manufacturing, half-cell and full-cell test benches, XPS, XRD, TEM, Raman, EDAX, SEM, EIS, and ESEM equipment, unique in-situ measurement techniques and test benches (Environmental EM, Transient Mass-Spectrometer-MS, and IR Optical Temperature measurements). In addition, computational capabilities have been developed culminating in a multi-scale multi-physics fuel cell simulation code, DREAM-SOFC, as well as a Beowulf cluster with 64 CPU units. We have trained 16 graduate students, 10 postdoctoral fellows, and recruited 4 new young faculty members who have actively participated in the EPSCoR project. All four of these faculty members have already been promoted to the tenured associate professor level. With the help of these faculty and students, we were able to secure 14 research awards/contracts amounting to a total of circa $5.0 Million external funding in closely related areas of research. Using the facilities mentioned above, the effects of PH3, HCl, Cl2, and H2S on cell performance have been studied in detail, mechanisms have been identified, and also remedies have been proposed and demonstrated in the laboratory. For example, it has been determined that PH3 reacts rapidly with Ni to from secondary compounds which may become softer or even melt at high temperature and then induce Ni migration to the surface of the cell changing the material and micro-structural properties of the cell drastically. It is found that the extent of steam and current load accelerate the degradation caused by PH3. A unique filtering technique has been proposed to reduce the effect of PH3. In addition, various cell materials have been proposed to reduce the rate of degradation caused by H2S. Furthermore, a three-dimensional, transient multi-physics model has been formulated to describe primary transport processes and electro-chemical reactions occurring within the cell. This model has been validated using data gathered from accelerated tests. The validated model then has been used to study the degradation rates under a range of operating conditions and impurity levels. This has resulted in a procedure that uses both experiments and simulations to predict the life-time of a cell operating with syngas with known concentration of trace impurities. Finally all the experience and knowledge gained has been disseminated via 39 journal papers and 43 presentations/posters/conference papers.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2018

Report on the FY18 creep rupture and creep-fatigue tests on the first commercial heat of Alloy 709

Creep, fatigue and creep-fatigue tests were performed on the Carlson plate of Alloy 709 (ID 58776). The plate, which is the first of the commercial heats tested, was divided into several sections, each undergoing different processing conditions. The effects of processing method and solution annealing temperature were studied in FY18 to inform best procedures for the second heat. The solution annealing temperature of 1050°C was found to be unacceptable due to the grain size being smaller than allowed by the specifications, as well as generally having poor creep properties. Both argon oxygen decarburization AOD and electro-slag remeltin ESR were found to have desirable properties, and the homogenization heat treatment was found to not significantly improve the mechanical properties.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Simulation-Based Inference for Neutrino Interaction Model Parameter Tuning

High-energy physics experiments studying neutrinos rely heavily on simulations of their interactions with atomic nuclei. Limitations in the theoretical understanding of these interactions typically necessitate ad hoc tuning of simulation model parameters to data. Traditional tuning methods for neutrino experiments have largely relied on simple algorithms for numerical optimization. While adequate for the modest goals of initial efforts, the complexity of future neutrino tuning campaigns is expected to increase substantially, and new approaches will be needed to make progress. In this paper, we examine the application of simulation-based inference (SBI) to the neutrino interaction model tuning for the first time. Using a previous tuning study performed by the MicroBooNE experiment as a test case, we find that our SBI algorithm can correctly infer the tuned parameter values when confronted with a mock data set generated according to the MicroBooNE procedure. This initial proof-of-principle illustrates a promising new technique for next-generation simulation tuning campaigns for the neutrino experimental community.

Tame-Narvaez, Karla Maria [Fermilab]↗
DOE OSTI2025

ROADRUNNER MiniFuel Experiment: Readiness for Insertion

The Research On ADvancing the peRformance of UraNium Nitrides in Extreme enviRonments (ROADRUNNER) campaign is a collaborative irradiation experiment designed to evaluate the performance of uranium nitride (UN) fuel fabricated with controlled variations in density and impurity content. Oak Ridge National Laboratory’s MiniFuel irradiation platform and the High Flux Isotope Reactor (HFIR) are being used to irradiate six targets containing 36 UN miniature disks. These targets have been assembled to systematically investigate burnup and temperature effects under accelerated irradiation conditions. This report documents the finalized test plan, describes the experiment assembly and subcapsule integration process, and confirms the readiness of all ROADRUNNER targets for HFIR insertion. All targets have passed quality control procedures, and five have begun irradiation. The campaign will provide critical performance data to support fuel model validation and future UN qualification efforts.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

ROADRUNNER MiniFuel Experiment: Readiness for Insertion

The Research On ADvancing the peRformance of UraNium Nitrides in Extreme enviRonments (ROADRUNNER) campaign is a collaborative irradiation experiment designed to evaluate the performance of uranium nitride (UN) fuel fabricated with controlled variations in density and impurity content. Oak Ridge National Laboratory’s MiniFuel irradiation platform and the High Flux Isotope Reactor (HFIR) are being used to irradiate six targets containing 36 UN miniature disks. These targets have been assembled to systematically investigate burnup and temperature effects under accelerated irradiation conditions. This report documents the finalized test plan, describes the experiment assembly and subcapsule integration process, and confirms the readiness of all ROADRUNNER targets for HFIR insertion. All targets have passed quality control procedures, and five have begun irradiation. The campaign will provide critical performance data to support fuel model validation and future UN qualification efforts.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Mechanical Characterization Study of Sintered Silver Pastes: Preprint

Sintered silver-based bonded interfaces are a critical enabling technology for high-temperature, compact, high-performance, and reliable wide-bandgap packages and components. High-pressure (about 40 MPa) sintered silver interfaces have been implemented commercially, most notably the commercial products offered by Semikron. To reduce manufacturing complexity, there is significant industry interest in pressure-less sintered silver interfaces. To this end, current formulations of sintered silver paste are comprised of purely nano-sized silver particles or a combination of nano- and micro-sized silver particles/flakes. It is essential to quantify the mechanical properties and determine the reliability of these interfaces prior to use in automotive power electronics applications. In this paper, research efforts at the National Renewable Energy Laboratory, in collaboration with Virginia Polytechnic Institute and State University and an industry partner, in optimizing the synthesis procedure and mechanical characterization of sintered silver double-lap samples are described. These double-lap samples were synthesized using pressure-less sintering techniques. Shear testing was conducted at multiple temperatures and displacement rates on these samples sintered using two types of sintered silver pastes, one of them consisting of nano-silver particles and the other a hybrid paste or a combination of nano- and micron-sized silver flakes, employed in a double-lap configuration. Maximum values of shear stress obtained from the characterization study are reported.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2016

Determination of the mechanical properties of blisters by nanoindentation

In light-water reactors, a zirconium oxide layer will be formed at the outer surface of the fuel cladding as a consequence of the chemical reaction which takes place between zirconium and the cooling water. This zirconium oxide layer is a good thermal insulator, but at some point, it may spall-out. As a consequence, a cold spot will be formed at the outer surface of the cladding. In this situation, the hydrogen will quickly migrate to this spot to form a highly-enriched hydride zone, known as blister. In this work, an experimental procedure has been devised to produce blisters with a similar shape to the ones reported in the literature for irradiated cladding with severe hydriding. Nano-indentation tests were performed on blisters prepared in laboratory. A numerical simulation by the finite element method was developed to fit the load versus penetration depth data from the aforementioned nano-indentation tests. By means of an inverse process which combines experimental data and numerical simulations, the constitutive equation of the blister was determined. The process has been used to calculate the plastic stress-strain curve of the blister under study at room temperature. The results show an almost perfect numerical fitting of the experimental data.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2025

Simulation-based inference for neutrino interaction model parameter tuning

High-energy physics experiments studying neutrinos rely heavily on simulations of their interactions with atomic nuclei. Limitations in the theoretical understanding of these interactions typically necessitate ad hoc tuning of simulation model parameters to data. Traditional tuning methods for neutrino experiments have largely relied on simple algorithms for numerical optimization. While adequate for the modest goals of initial efforts, the complexity of future neutrino tuning campaigns is expected to increase substantially, and new approaches will be needed to make progress. In this paper, we examine the application of simulation-based inference (SBI) to the neutrino interaction model tuning for the first time. Using a previous tuning study performed by the MicroBooNE experiment as a test case, we find that our SBI algorithm can correctly infer the tuned parameter values when confronted with a mock data set generated according to the MicroBooNE procedure. This initial proof-of-principle illustrates a promising new technique for next-generation simulation tuning campaigns for the neutrino experimental community.

Tame-Narvaez, Karla [Fermilab] (ORCID:000000022249↗
DOE OSTI2016

Improving Bending Moment Measurements on Wind Turbine Blades

Full-scale fatigue testing of wind turbine blades is conducted using resonance test techniques where the blade plus additional masses is excited at its first resonance frequency to achieve the target loading amplitude. Because there is not a direct relationship between the force applied by an actuator and the bending moment, the blade is instrumented with strain gauges that are calibrated under static loading conditions to determine the sensitivity or relationship between strain and applied moment. Then, during dynamic loading the applied moment is calculated using the strain response of the structure. A similar procedure is also used in the field to measure in-service loads on turbine blades. Because wind turbine blades are complex twisted structures and the deflections are large, there is often significant cross-talk coupling in the sensitivity of strain gauges placed on the structure. Recent work has shown that a sensitivity matrix with nonzero cross terms must be employed to find constant results when a blade is subjected to both flap and lead-lag loading. However, even under controlled laboratory conditions, potential for errors of 3 percent or more in the measured moment exist when using the typical cross-talk matrix approach due to neglecting the influence of large deformations and torsion. This is particularly critical when considering a biaxial load as would be applied on the turbine or during a biaxial fatigue test. This presentation describes these results demonstrating errors made when performing current loads measurement practices on wind turbine blades in the lab and evaluating potential improvements using enhanced cross-talk matrix approaches and calibration procedures.

17 WIND ENERGY↗