SEARCH · Search NASA

Results for “coupling coefficient”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53

All sources NASA NTRS DOE OSTI

DOE OSTI2017

Quantitative Determination on Ionic-Liquid-Gating Control of Interfacial Magnetism

Ionic-liquid gating on a functional thin film with a low voltage has drawn a lot of attention due to rich chemical, electronic, and magnetic phenomena at the interface. A key challenge in quantitative determination of voltage-controlled magnetic anisotropy (VCMA) in Au/[DEME] + [TFSI] - /Co field-effect transistor heterostructures is addressed. The magnetic anisotropy change as response to the gating voltage is precisely detected by in situ electron spin resonance measurements. Furthermore, a reversible change of magnetic anisotropy up to 219 Oe is achieved with a low gating voltage of 1.5 V at room temperature, corresponding to a record high VCMA coefficient of ≈146 Oe V -1 . Two gating effects, the electrostatic doping and electrochemical reaction, are distinguished at various gating voltage regions, as confirmed by X-ray photoelectron spectroscopy and atomic force microscopy experiments. Our work shows a unique ionic-liquid-gating system for strong interfacial magnetoelectric coupling with many practical advantages, paving the way toward ion-liquid-gating spintronic/electronic devices.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Effect of solution chemistry on the iodine release from iodoapatite in aqueous environments

To ensure the safe disposal of nuclear waste, understanding the release process of radionuclides retained in the nuclear waste forms is of vital importance. Iodoapatite Pb 9.85 (VO 4 ) 6 I 1.7 , a potential waste form for iodine-129, was selected as a model system for ceramic waste forms in this study to understand the effect of aqueous species on iodine release. Semi-dynamic leaching tests were conducted on bulk samples in cap-sealed Teflon vessels with 0.1 mol/L NaCl, Na 2 CO 3 , Na 3 PO 4 , and Na 2 SO 4 solutions under 90 °C, fixed sample surface area to solution volume ratio of 5/m, and periodic replacement of leaching solutions. The reacted solutions were then analyzed by Inductively Coupled Plasma-Mass Spectrometry and Inductively Coupled Plasma-Optical Emission Spectrometry; the leached surfaces were characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. The finding shows that, compared to deionized water, the ion-rich solutions enhanced the iodine release as a result of the increased ionic strength, reduced activity coefficient of dissolved species, and increased solution pH. Surface reactions can lead to the formations of secondary phases by ion-exchange and precipitation. These findings indicate that an ion-rich environment in the geological repository can be detrimental to the disposal safety of the nuclear waste form.

36 MATERIALS SCIENCE↗

DOE OSTI2013

Rotational relaxation of CS by collision with ortho- and para-H{sub 2} molecules

Quantum mechanical investigation of the rotationally inelastic collisions of CS with ortho- and para-H{sub 2} molecules is reported. The new global four-dimensional potential energy surface presented in our recent work is used. Close coupling scattering calculations are performed in the rigid rotor approximation for ortho- and para-H{sub 2} colliding with CS in the j = 0–15 rotational levels and for collision energies ranging from 10{sup −2} to 10{sup 3} cm{sup −1}. The cross sections and rate coefficients for selected rotational transitions of CS are compared with the ones previously reported for the collision of CS with He. The largest discrepancies are observed at low collision energy, below 1 cm{sup −1}. Above 10 cm{sup −1}, the approximation using the square root of the relative mass of the colliders to calculate the cross sections between a molecule and H{sub 2} from the data available with {sup 4}He is found to be a good qualitative approximation. The rate coefficients calculated with the electron gas model for the He-CS system show more discrepancy with our accurate results. However, scaling up these rates by a factor of 2 gives a qualitative agreement.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2016

Numerical investigation of electromagnetic pulse welded interfaces between dissimilar metals

The quality of an electromagnetic pulse weld is strongly affected by a variety of interacting physical phenomena including large plastic deformation, materials mixing, localised heating and rapid cooling, and possible localised melting and interfacial cracks and void. In the present study, a thermomechanically coupled dynamic model has been developed to quantitatively resolve the high speed impact joining interface characteristics as well as the process induced interface temperature evolution, defect formation and possible microstructural composition variations. Reasonably good agreement has been obtained between the predicted results and the experimental measurements in terms of interfacial morphology characteristics. The modelling framework is expected to provide further understanding of the hierarchical interfacial features of the non-equilibrium material joining process and the weld formation mechanisms.

Xu, W.↗

DOE OSTI2022

Total metals, sulfur and organic carbon data; Slate River floodplain, Crested Butte, CO; March 2021-October 2021

This data package includes processed and undiluted measurements for metal, sulfur and organic carbon concentrations from pore water (groundwater) samples from the Slate River floodplain of Crested Butte, CO, a focus field site for the SLAC Floodplain Hydro-Biogeochemistry SFA. The data was generated as part of the work targeting the overarching research question for the SLAC SFA: How do ubiquitous subsurface interfaces mediate molecular-scale biogeochemical processes and groundwater quality in floodplains and watersheds? Samples were collected between March and October of 2021. These measurements were all recorded at the Environmental Measurements Facility (EM-1) at Stanford University in Stanford, CA. Groundwater samples were extracted from a network of installed rhizon (Rhizosphere Research Products, part no. 19.60.21F, 0.6 micrometer mesh size) and piezometer wells within the river floodplain. All water samples were shaded from sun exposure during extraction from the subsurface and preserved at 2C until measured at EM-1.Analysis by ICP-MS:Measurements for total metals were performed on an inductively coupled plasma optical emission spectrometer (ICP-OES; iCAP 6300, Thermo Scientific, Cambridge, U.K.). Calibration standards were prepared from the mulit element stock solution (Sigma-Aldrich Multielement standard for ICP, St. Louis, MO) using matrix matched to sample solutions (2% HNO3). Calibration curves included 5 points with correlation coefficients of >0.99. The QC protocol includes a continuing calibration blank and quality control samples that are analyzed just after calibration and again every 20 samples and at the completion of the run. Acceptable QC responses must be between 90-110% of the certified value. Analysis by Total Organic Carbon:Dissolved organic carbon concentrations were quantified on a total organic carbon (TOC) analyzer (TOC-L, Shimadzu, Kyoto, Japan) running the NPOC method. Standard curves were developed using an Organic Carbon Standard from RICCA Chemical Company (Arlington,TX). A series of 4 to 6 standards were automatically diluted by the instrument in a concentration range that spans that of the samples. A blank sample was run just after the calibration curve and at the end of the run. A QC sample was run every 25 samples. Acceptable QC responses must be between 90-110% of the certified value.All files are in csv format.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2017

Characterization of the pyroelectric coefficient of a high-temperature sensor

Temperature is one of the most important thermodynamic properties measured and controlled in energy generation systems. To operate the energy system at optimum operating conditions for lower emission and higher efficiency, it is important to measure real-time temperatures. Furthermore, temperature sensing in intense environments is necessary since most sensors in energy systems get exposed to elevated temperatures, corrosive environments, and elevated pressures. One of the solutions for developing harsh environment sensors is to use ceramic materials, especially functional ceramics such as pyroelectrics. Pyroelectric ceramics could be used to develop active sensors for both temperature and pressure due to their capabilities in coupling energy among mechanical, thermal, and electrical domains. In this study, Lithium niobate (LiNbO 3 ) pyroelectric ceramic material was used to develop a temperature sensor for high-temperature applications. LiNbO 3 has high Curie temperature (1210°C) compared to other pyroelectric ceramic materials. A high Curie temperature material is important since the polarization properties of the material break down above the Curie temperature. Hence, the use of a material with a higher Curie temperature, such as LiNbO 3 , makes it promising to be used as a sensing material for high-temperature applications. A study was performed to actively measure the temperature up to 500°C using a pyroelectric ceramic lithium niobate (LiNbO 3 ) as a sensor material. Due to the non-linear pyroelectric response of LiNbO 3 , the temperature-dependent pyroelectric coefficient of LiNbO 3 was measured with a dynamic pyroelectric coefficient technique in temperature ranges up to 500°C. Temperature-dependent pyroelectric coefficient of LiNbO 3 was found to increase from −0.5 × 10 −5 to −3.70 × 10 −5 C/m 2 °C from room temperature to 500°C. The LiNbO 3 sensor was then tested for higher temperature sensing at 220°C, 280°C, 410°C, and 500°C and has shown 4.31%, 2.1%, 0.4%, and 0.6% deviation, respectively, compared with thermocouple measurements.

Sarker, Md Rashedul H.↗

DOE OSTI2024

Analytic amplitudes for a pair of Higgs bosons in association with three partons

The pair production of Higgs bosons at the LHC can give information about the triple Higgs boson coupling. We perform an analytic one-loop calculation of the amplitudes for a pair of Higgs bosons in association with three partons, retaining the exact dependence on the quark mass circulating in the loop. These amplitudes constitute the real radiation corrections in the calculation of Higgs boson pair production at next-to-leading order in the strong coupling. The results of an analytic generalised-unitarity computation are simplified via analytic reconstruction in spinor variables. Compact ansätze for kinematic pole residues are iteratively fitted via p-adic evaluations near said poles and subtracted until no pole remains. A new ansatz construction is introduced to minimally parametrise coefficients of amplitudes with multiple massive external legs. The simplified expressions are faster to evaluate than automatic codes and can lead to more stable results near singular regions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Melt compounding of spray-dried cellulose nanofibrils/polypropylene and their application in 3D printing

Abstract Micro- and nano-scale cellulosic fillers exhibit excellent dispersion and distribution within a thermoplastic matrix during the process of melt compounding or injection molding. In this study, spray-dried cellulose nanofiber (SDCNF) powders were manufactured using a pilot-scale rotating disk atomizer spray dryer. Bleached Kraft pulp (BKP), unbleached Kraft pulp (UKP), and old corrugated cardboard pulp (OCC) fibrillated at a fines level of 90% were used as feedstock materials for spray-drying. BKP-, UKP-, and OCC- SDCNFs were compounded with polypropylene using a twin screw co-rotating extruder. Maleic anhydride grafted polypropylene (MAPP) was used as a coupling agent in the composite formulations. The tensile, flexural, and impact properties of SDCNF-filled PP composites increased at 10 wt% SDCNF loading. The presence of SDCNFs in the PP matrix resulted in faster crystallization and a 12% reduction in the degree of crystallinity of the neat PP. The coefficient of thermal expansion (CTE) of neat PP was reduced by up to 31% attributable to the presence of the SDCNFs. Application of the SDCNF-reinforced PP composites in 3D printing reduced the shrinkage rate of the printed neat PP by 39%, and the printability of the PP was significantly improved with the addition of the SDCNFs.

Materials Science↗

DOE OSTI2017

Hot deformation characteristics of AZ80 magnesium alloy: Work hardening effect and processing parameter sensitivities

Isothermal compression experiment of AZ80 magnesium alloy was conducted by Gleeble thermo-mechanical simulator in order to quantitatively investigate the work hardening (WH), strain rate sensitivity (SRS) and temperature sensitivity (TS) during hot processing of magnesium alloys. The WH, SRS and TS were described by Zener-Hollomon parameter (Z) coupling of deformation parameters. The relationships between WH rate and true strain as well as true stress were derived from Kocks-Mecking dislocation model and validated by our measurement data. The slope defined through the linear relationship of WH rate and true stress was only related to the annihilation coefficient Ω. Obvious WH behavior could be exhibited at a higher Z condition. Furthermore, we have identified the correlation between the microstructural evolution including β-Mg17Al12 precipitation and the SRS and TS variations. Intensive dynamic recrystallization and homogeneous distribution of β-Mg17Al12 precipitates resulted in greater SRS coefficient at higher temperature. The deformation heat effect and β-Mg17Al12 precipitate content can be regarded as the major factors determining the TS behavior. At low Z condition, the SRS becomes stronger, in contrast to the variation of TS. The optimum hot processing window was validated based on the established SRS and TS values distribution maps for AZ80 magnesium alloy.

36 MATERIALS SCIENCE↗

DOE OSTI2025

A Meta-Generalized Gradient Approximation for the Cavity-Dependent Exchange-Correlation Interaction in Strongly Coupled Light–Matter Systems

Strong light–matter coupling in optical cavities enables the manipulation of chemical and physical properties without altering molecular composition. Theoretical modeling of such phenomena requires exchange-correlation (XC) functionals that account for both electron–electron and electron–photon (ep) interactions within quantum electrodynamical density functional theory (QEDFT). In this work, we develop a meta-generalized gradient approximation (meta-GGA) specifically targeting the cavity-dependent XC interaction in strongly coupled light–matter systems. This novel approximation is built upon a new semilocal polarizability approximation, which draws from the jellium-with-a-gap model, and can be extended to a “global hybrid” variant that goes beyond the isotropic model from previous approximations. The polarizability model yields significantly improved dispersion coefficients and benchmark calculations with the cavity-dependent XC functional demonstrate improved agreement with QED Hartree–Fock (QED-HF) reference energies. Application to the regioselectivity of brominated nitrobenzene intermediates reveals the functional’s capacity to capture cavity-induced energetic shifts. In conclusion, our results advance the Jacob’s ladder of functionals for QEDFT and provide a practical tool for modeling polaritonic chemistry.

Approximation↗

DOE OSTI2017

Quantum criticality among entangled spin chains

Here, an important challenge in magnetism is the unambiguous identification of a quantum spin liquid, of potential importance for quantum computing. In such a material, the magnetic spins should be fluctuating in the quantum regime, instead of frozen in a classical long-range-ordered state. While this requirement dictates systems wherein classical order is suppressed by a frustrating lattice, an ideal system would allow tuning of quantum fluctuations by an external parameter. Conventional three-dimensional antiferromagnets can be tuned through a quantum critical point—a region of highly fluctuating spins—by an applied magnetic field. Such systems suffer from a weak specific-heat peak at the quantum critical point, with little entropy available for quantum fluctuations. Here we study a different type of antiferromagnet, comprised of weakly coupled antiferromagnetic spin-1/2 chains as realized in the molecular salt K 2 PbCu(NO 2 ) 6 . Across the temperature–magnetic field boundary between three-dimensional order and the paramagnetic phase, the specific heat exhibits a large peak whose magnitude approaches a value suggestive of the spinon Sommerfeld coefficient of isolated quantum spin chains. These results demonstrate an alternative approach for producing quantum matter via a magnetic-field-induced shift of entropy from one-dimensional short-range order to a three-dimensional quantum critical point.

36 MATERIALS SCIENCE↗

DOE OSTI2015

Magnetite nanoparticles coated glass wool for As(V) removal from drinking water

Arsenic (As) removal from contaminated groundwater is a key environmental concern worldwide. In this study, glass wool was coated with magnetite nanoparticles under argon gas flow and magnetite coated glass wool have been investigated for application as an adsorbent for As(V) removal from water. The adsorbent was characterized by using Scanning Electron Microscopy (SEM) and arsenic contaminated water treated with adsorbent was analyzed by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The ICP-MS results showed that 10 g/L of adsorbent removed 99.4% of As(V) within 5 hours at pH-7 and initial arsenic concentration of 360µg/L. Adsorption kinetics data fitted well in pseudo-first-order kinetics model with high correlation coefficient (R{sup 2} = 0.995). As magnetite nanoparticles coated glass wool showed favorable adsorption behavior for As(V), it can be a promising tool for water purification.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Vertical instability forecasting and controllability assessment of multi-device tokamak plasmas in DECAF with data-driven optimization

Abstract Reliable vertical position control will be an essential element of any future tokamak-based fusion power plant in order to reduce disruptions and maximize performance. We investigate methods to improve vertical controllability boundary determination in plasma operational space and demonstrate a data-driven approach based on direct pseudoinversion of operational space data that is rigorously quantitative, applicable in real-time plasma control systems, and physically intuitive to interpret. Applied to historical shot data from entire run campaigns on the MAST-U, KSTAR, and NSTX tokamaks, this approach, implemented in DECAF, improves vertical displacement event identification accuracy to 98.9%–100%. Further, we explore the application of a physics-based vertical stability metric as an early warning forecaster for vertical displacement events. The development of a linear surrogate model for the plasma current density profile, with a coefficient of determination of 0.992 on the training dataset, enables potential employment of this forecaster in real-time. The application of this approach on historical data from the MAST-U MU02 campaign yields a forecaster with 62.6% accuracy, indicating promise for this method when further refined and potentially coupled with other stability metrics.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2025

Temperature and Strain Sensing Characteristics of a 128° YX-Cut LiNbO 3 Rayleigh-Mode SAW Sensor From Room to Cryogenic Temperatures

Accurate, passive, and wireless monitoring of cryogenic hardware is essential for high-energy physics, space propulsion, and biomedical instrumentation. Here, this study quantifies the coupled temperature-strain behavior of Rayleigh-mode surface acoustic-wave (SAW) delay-line sensors fabricated on 128° YX-cut LiNbO 3 . A nonlinear finite element (FE) model incorporating Varshni-based elastic constants, higher-order thermal expansion, and temperature-dependent piezo- and dielectric coefficients was developed and validated experimentally between 280K and 80K. Free-standing (first test condition) and bonded/wired (second test condition) devices exhibited indistinguishable thermal responses; the average temperature coefficient of delay (TCD) in the critical cryogenic range from 130K down to 80K differed by only 0.15 ppm/K (0.32%), confirming that bonding-induced stress is negligible. Over 280-80K the measured TCD was 61.77 ppm/K, while the FE model predicted an equivalent temperature coefficient of frequency (TCF) of −62.74 ppm/K with an overall coefficient of determination R2 = 0.998. In the critical cryogenic interval 130-80K the TCD fell to 47.66 ppm/K, indicating improved thermal stability at low temperature. Controlled loading (0-300 με) revealed a strain coefficient of delay (SCD) that rises from 0.53 ± 0.02 ppm/με at 300K to 1.05 ± 0.02 ppm/με at 80K. This modest sensitivity confirms that, for temperature sensing, strain is a second-order perturbation above 135K but must be compensated at deeper cryogenic levels. Overall, this work establishes a predictive multiphysics model together with repeatable wired measurements that confirm the suitability of SAW sensors for temperature and strain monitoring in extreme cryogenic environments, while also providing a baseline for future wireless implementations.

25 ENERGY STORAGE↗

DOE OSTI2014

TOUGHREACT (TREACT) v3.32

TOUGHREACT V3.32 is a 3-D reactive transport code that handles to non-isothermal, multiphase/multicomponent fluid flow, heat transport, aqueous and gaseous species advection-diffusion, and equilibrium/kinetic water-gas-rock-biological reactions. TOUGHREACT V3.32 is based on TOUGHREACT V3.0-OMP, with several new features including temperature and species-dependent aqueous species diffusion coefficients, addition of the EWASG EOS module, a new generalized Monod kinetics function, time-dependent pressure-temperature boundary conditions, new VisIt-compatible tecplot-format output files (with new flux and velocity vector component outputs), new input and output options, and improved global water mass balance and coupling between flow, transport and reactive chemistry.

Sonnenthal, Eric↗

DOE OSTI2019

Seismic Noise Induced by Wind Turbine Operation and Wind Gusts

Improved seismic noise characterization, due to varied sources, may benefit traditional applications. Some examples are earthquake detection, Earth structure research, and nuclear testing. This improvement could also permit use of seismic data in transdisciplinary research such as wind gust detection and wind turbine (WT) condition monitoring. However, it is a challenging task to unambiguously quantify relationships between potential sources of seismic noise and the actual seismic response. In this article, we analyze seismic and meteorological data (wind speed and pressure), measured at a remote site in a complex terrain area in eastern Portugal, to examine seismic signatures from WT operational status and wind gusts. Results presented herein show the following: (1) WT signatures in seismic data can be used to accurately determine WT-operational status. Attenuation of WT signatures in seismic data exhibits an exponential decay with distance, with attenuation coefficients that scale with frequency. (2) After WT signatures are removed from seismic power spectra, wind gust signatures remain. Analyses of these data further indicate that it may be possible to extract quantitative wind gust estimates from seismic data and decompose them into pressure and shear stress drivers of this coupling.

Geochemistry & Geophysics↗

DOE OSTI2017

SIERRA Low Mach Module: Fuego Theory Manual (V.4.44)

The SIERRA Low Mach Module: Fuego along with the SIERRA Participating Media Radiation Module: Syrinx, henceforth referred to as Fuego and Syrinx, respectively, are the key elements of the ASCI fire environment simulation project. The fire environment simulation project is directed at characterizing both open large-scale pool fires and building enclosure fires. Fuego represents the turbulent, buoyantly-driven incompressible flow, heat transfer, mass transfer, combustion, soot, and absorption coefficient model portion of the simulation software. Syrinx represents the participating-media thermal radiation mechanics. This project is an integral part of the SIERRA multi-mechanics software development project. Fuego depends heavily upon the core architecture developments provided by SIERRA for massively parallel computing, solution adaptivity, and mechanics coupling on unstructured grids.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2017

SIERRA Low Mach Module: Fuego User Manual (V.4.44)

97 MATHEMATICS AND COMPUTING↗