Search NASA⌕ Search

SEARCH · Search NASA

Results for “medium”

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.

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

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Microstructures and Properties of Medium Manganese Sheet Steels - Strategies and Opportunities

Medium manganese steels, with 3 to 10 wt pct Mn, have been shown to be capable of being thermally-processed to produce sheet products with a variety of strength-ductility combinations and thus are receiving considerable attention as candidates for 3rd generation advanced high strength steels (3GAHSS). The steels typically contain refined microstructures with characteristic microstructural dimensions of 1 to 2 µm and consist of significant amounts of retained austenite in a fine grained ferritic matrix. Strategies for development of medium manganese steels are reviewed and results of recent property predictions based on composite modeling are presented. The importance of controlling austenite stability is illustrated with data on medium Mn (7 and 10 wt pct.), low carbon (0.1 and 0.15 wt pct) steels. Important forming variables (strain, strain rate, and temperature) are discussed, along with a consideration of yield point elongation, present in many medium Mn steels.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Quarkonium in-medium properties from realistic lattice NRQCD

Here, we present the final results of our high statistics study on the properties of bottomonium and charmonium at finite temperature. We focus on the temperature range around the crossover transition 150 ≤ T ≤ 410MeV, relevant for current heavy ion collision experiments. The QCD medium degrees of freedom, which consist of dynamical u,d, and s quarks and gluons are captured by realistic state-of-the art (m π ≈ 161MeV) lattice QCD simulations of the HotQCD collaboration. For the heavy quarks we deploy the non-relativistic effective field theory of QCD, NRQCD. The in-medium properties of quarkonium are deduced from their spectral functions, which are reconstructed using improved and novel Bayesian approaches. Through a systematic analysis we shed light on the origin of the discrepancies in melting temperatures previously reported in the literature, showing that they are owed to underestimated methods uncertainties of the deployed spectral reconstructions. Our simulations corroborate a picture of sequential in-medium modification, ordered according to the vacuum binding energy of the states. As a central quantitative result, our study reveals how the mass of the heavy quarkonium ground state reduces as temperature increases. The observed spectral modifications are interpreted in the light of, and compared to previous studies based on the complex lattice potential for heavy quarkonium. Furthermore for the first time we provide a robust picture of in-medium heavy quarkonium modification in the quark-gluon plasma consistent among different non-relativistic methods. We also critically discuss the perspectives for improving on these results.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Ensuring combination of strength, ductility and toughness in medium-manganese steel through optimization of nano-scale metastable austenite

Highlights: • Medium-Mn steel was innovatively designed for medium to heavy steel plates. • Three intercritical annealing processes were adopted to ensure TRIP effect. • Austenite-martensite submicro-laminate structure was obtained after annealing. • The reversed austenite with different stability led to improved ductility. • TRIP effect induced by metastable austenite contributed excellent impact properties. - Abstract: Medium-Mn steel was innovatively designed in terms of alloying elements for medium to heavy steel plates to obtain combination of high strength, good ductility, and excellent low temperature toughness. Martensite was the dominant microstructure in the directly quenched steel plate because of high hardenability obtained by the addition of 5.6 wt% Mn. Three intercritical annealing processes were adopted to ensure transformation-induced-plasticity (TRIP) effect through optimization of the volume fraction, morphology, and C and Mn-enriched reversed austenite. On annealing, the dislocation density of martensite plate was decreased because of recovery and recrystallization, and metastable austenite film nucleated at the interface. Both thermal and mechanical stability of austenite decreased with increase in annealing temperature. The high yield strength of 840 MPa, good elongation after fracture of 24.3%, and excellent toughness at − 60 °C of 130.3 J was obtained at intermediate annealing temperature of 650 °C, and the volume fraction of reversed austenite at room temperature and − 80 °C was 22% and 17%, respectively. The reversed austenite exhibited different stability with increased tensile strain, leading to improved ductility and delayed necking. Moreover, the crack initiation energy and crack propagation energy were increased via dynamic stress partitioning and relaxation together with the transformation of metastable austenite. Thus, significant degree of TRIP effect induced by moderate stability of austenite played an important role in governing mechanical properties.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Biohydrogen production from hyperthermophilic anaerobic digestion of fruit and vegetable wastes in seawater: Simplification of the culture medium of Thermotoga maritima

Highlights: • H2 production from fruit and vegetable wastes by T. maritima in seawater was studied. • The supply of seawater can replace some components necessary for T. maritima. • Using natural seawater medium recorded similar results to the mineral basal medium. • No H{sub 2} production by T. maritima in absence of nitrogen and sulfur sources. - Abstract: Biohydrogen production by the hyperthermophilic and halophilic bacterium T. maritima, using fruit and vegetable wastes as the carbon and energy sources was studied. Batch fermentation cultures showed that the use of a culture medium containing natural seawater and fruit and vegetable wastes can replace certain components (CaCl{sub 2}, MgCl{sub 2}, Balch's oligo-elements, yeast extract, KH{sub 2}PO{sub 4} and K{sub 2}HPO{sub 4}) present in basal medium. However, a source of nitrogen and sulfur remained necessary for biohydrogen production. When fruit and vegetable waste collected from a wholesale market landfill was used, no decreases in total H{sub 2} production (139 mmol L{sup −1}) or H{sub 2} yield (3.46 mol mol{sup −1}) was observed.

08 HYDROGEN↗
DOE OSTI2023

Medium-Range Ordering in the Ionic Glass Electrolytes LiPON and LiSiPON

In this work, we provide an in-depth structural characterization of the amorphous ionic glasses LiPON and LiSiPON with high Li content. Based on ab initio molecular dynamics simulations, the structure of these materials is an inverted structure with either isolated polyanion tetrahedra or polyanion dimers in a Li+ matrix. Based on neutron scattering data, this type of inverted structure leads to a significant amount of medium-range ordering in the structure, as demonstrated by two sharp diffraction peaks and a periodic structural oscillation in the density function G(r). While this medium-range ordering is commonly observed in liquids and metallic glasses, it has not previously been observed in oxides. On a local scale, adding N and Si increases the number of anion bridges and polyanion dimer structures, leading to higher ionic conductivity. In the medium-range ordering, the addition of Si leads to more disorder in the polyanion substructure but a significant increase in the ordering of the O substructure. Finally, we demonstrate that this inverted structure with medium-range ordering results in a glassy material that is both mechanically stiff and ductile on the nanoscale.

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

Influence of the Ag concentration on the medium-range order in a CuZrAlAg bulk metallic glass

Fluctuation electron microscopy of bulk metallic glasses of CuZrAl(Ag) demonstrates that medium-range order is sensitive to minor compositional changes. Furthermore, by analyzing nanodiffraction patterns medium-range order is detected with crystal-like motifs based on the B2 CuZr structure and its distorted structures resembling the martensitic ones. This result thus demonstrates some structural homology between the metallic glass and its high temperature crystalline phase. The amount of medium-range order seems slightly affected with increasing Ag concentration (0, 2, 5 at.%) but the structural motifs of the medium-range ordered clusters become more diverse at the highest Ag concentration. The decrease of dominant clusters is consistent with the destabilization of the B2 structure measured by calorimetry and accounts for the increased glass-forming ability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Analysis of the light shift in the hyper-Ramsey scheme of two-level atom interrogation in an optically dense medium

The properties of the Ramsey resonance and its sensitivity to the light shift of the atomic transition frequency are investigated in the case of the hyper-Ramsey interrogation in an optically dense medium of cold atoms. The shape of the interrogating pulses varies significantly due to the processes of absorption and dispersion in the atomic medium, which leads to a distortion of the Ramsey resonance and a periodic change in the central minimum to the maximum and vice versa. The dependence of the position of the central resonance on the light shift of the atomic transition is found with the attenuation of radiation in the medium taken into account. It is shown that in a certain section of the medium this dependence becomes N-shaped. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Generalised hyper-Ramsey spectroscopy of two-level atoms in an optically dense medium

The peculiarities of Ramsey resonance and its sensitivity to the light shift from an optically dense medium of cold atoms are investigated. Different composite pulse protocols for clock spectroscopy, including hyper-Ramsey, modified and generalised hyper-Ramsey schemes, are compared. Error signals change significantly due to the processes of absorption and dispersion in the atomic medium. The dependence of the position of the central fringe resonance with a residual uncompensated light shift of the atomic transition is studied with the attenuation of the radiation intensity in the medium taken into account. It is shown that using a combination of generalised hyper-Ramsey error signals allows one to suppress the sensitivity to the light shift for any length of the medium. (laser cooling of atoms)

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

TWO SNe Ia AT REDSHIFT ∼2: IMPROVED CLASSIFICATION AND REDSHIFT DETERMINATION WITH MEDIUM-BAND INFRARED IMAGING

We present two supernovae (SNe) discovered with the Hubble Space Telescope (HST) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, an HST multi-cycle treasury program. We classify both objects as SNe Ia and find redshifts of z = 1.80 ± 0.02 and 2.26{sup +0.02}{sub −0.10}, the latter of which is the highest redshift SN Ia yet seen. Using light curve fitting we determine luminosity distances and find that both objects are consistent with a standard ΛCDM cosmological model. These SNe were observed using the HST Wide Field Camera 3 infrared detector, with imaging in both wide- and medium-band filters. We demonstrate that the classification and redshift estimates are significantly improved by the inclusion of single-epoch medium-band observations. This medium-band imaging approximates a very low resolution spectrum (λ/Δλ ≲ 100) which can isolate broad spectral absorption features that differentiate SNe Ia from their most common core collapse cousins. This medium-band method is also insensitive to dust extinction and (unlike grism spectroscopy) it is not affected by contamination from the SN host galaxy or other nearby sources. As such, it can provide a more efficient—though less precise—alternative to IR spectroscopy for high-z SNe.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

LOCAL INTERSTELLAR MEDIUM: SIX YEARS OF DIRECT SAMPLING BY IBEX

The Interstellar Boundary Explorer (IBEX) has been directly observing neutral atoms from the local interstellar medium for the last six years (2009–2014). This paper ties together the 14 studies in this Astrophysical Journal Supplement Series Special Issue, which collectively describe the IBEX interstellar neutral results from this epoch and provide a number of other relevant theoretical and observational results. Interstellar neutrals interact with each other and with the ionized portion of the interstellar population in the “pristine” interstellar medium ahead of the heliosphere. Then, in the heliosphere's close vicinity, the interstellar medium begins to interact with escaping heliospheric neutrals. In this study, we compare the results from two major analysis approaches led by IBEX groups in New Hampshire and Warsaw. We also directly address the question of the distance upstream to the pristine interstellar medium and adjust both sets of results to a common distance of ∼1000 AU. The two analysis approaches are quite different, but yield fully consistent measurements of the interstellar He flow properties, further validating our findings. While detailed error bars are given for both approaches, we recommend that for most purposes, the community use “working values” of ∼25.4 km s{sup −1}, ∼75.°7 ecliptic inflow longitude, ∼ −5.°1 ecliptic inflow latitude, and ∼7500 K temperature at ∼1000 AU upstream. Finally, we briefly address future opportunities for even better interstellar neutral observations to be provided by the Interstellar Mapping and Acceleration Probe mission, which was recommended as the next major Heliophysics mission by the NRC's 2013 Decadal Survey.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Heavy flavor quenching and flow: the roles of initial condition, pre-equilibrium evolution, and in-medium interaction

Within an advanced Langevin-hydrodynamics framework coupled to a hybrid fragmentation-coalescence hadronization model, we study heavy flavor quenching and flow in relativistic heavy-ion collisions. We investigate how the initial heavy quark spectrum, the in-medium energy loss and hadronization mechanisms of heavy quarks, the evolution profile of the pre-equilibrium stage, the medium flow, and the temperature dependence of heavy quark diffusion coefficients influence the suppression and elliptic flow of heavy mesons at the RHIC and the LHC. Our results show that the different modeling of initial conditions, pre-equilibrium evolution, and in-medium interactions can individually yield uncertainties of approximately 10-40% in D meson suppression and flow at a low transverse momentum. Furthermore, we also find that proper combinations of collisional versus radiative energy loss, coalescence versus fragmentation in hadronization, and the inclusion of medium flow are the most important factors for describing the suppression and elliptic flow of heavy mesons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Probing chiral interactions up to next-to-next-to-next-to-leading order in medium-mass nuclei

Here, we study ground-state energies and charge radii of closed-shell medium-mass nuclei based on novel chiral nucleon-nucleon (NN) and three-nucleon (3⁢𝑁) interactions, with a focus on exploring the connections between finite nuclei and nuclear matter. To this end, we perform in-medium similarity renormalization group (IM-SRG) calculations based on chiral interactions at next-to-leading order (NLO), N 2 ⁢LO, and N 3 ⁢LO, where the 3⁢𝑁 interactions at N 2⁢ LO and N 3 ⁢LO are fit to the empirical saturation point of nuclear matter and to the triton binding energy. Our results for energies and radii at N 2 ⁢LO and N 3 ⁢LO overlap within uncertainties, and the cutoff variation of the interactions is within the EFT uncertainty band. We find underbound ground-state energies, as expected from the comparison to the empirical saturation point. The radii are systematically too large, but the agreement with experiment is better. We further explore variations of the 3⁢𝑁 couplings to test their sensitivity in nuclei. While nuclear matter at saturation density is quite sensitive to the 3⁢𝑁 couplings, we find a considerably weaker dependence in medium-mass nuclei. In addition, we explore a consistent momentum-space SRG evolution of these NN and 3⁢𝑁 interactions, exhibiting improved many-body convergence. For the SRG-evolved interactions, the sensitivity to the 3⁢𝑁 couplings is found to be stronger in medium-mass nuclei.

ab initio calculations↗
DOE OSTI2015

Medium-induced flavor conversion and kaon spectra in electron-ion collisions

Multiple scattering and induced parton splitting lead to a medium modification of the QCD evolution for jet fragmentation functions and final hadron spectra. Medium-induced parton splittings not only lead to energy loss of leading partons and suppression of leading hadron spectra, but also modify the flavor composition of a jet due to induced flavor conversion via gluon emission and quark pair production and annihilation. By doing a numerical study of the medium-modified QCD evolution, leading K - strange meson spectra are found to be particularly sensitive to the medium-induced flavor conversion in semi-inclusive deeply inelastic scatterings (SIDIS) off a large nucleus. The induced flavor conversion can lead to an increased number of gluons and sea quarks in a jet shower and, as a consequence, enhance the leading K - spectrum to counter the effect of parton energy loss in SIDIS with large momentum fractions x B , where the struck quarks are mostly valence quarks of the nucleus.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

QED nuclear medium effects at EIC energies

Here, we present the first calculation of quantum electrodynamics (QED) nuclear medium effects under the experimental conditions of future Electron-Ion Collider (EIC) experiments. Our work offers numerical estimates, particularly in the context of inclusive deep inelastic scattering on a $^{208}_{82}$Pb nucleus. While prior studies have predominantly focused on elastic scattering, our investigation extends to the more complex scenarios of inelastic processes within a nuclear medium. Our findings suggest that the cross section corrections due to QED nuclear medium effects could be substantial, reaching or exceeding the level of experimental precision. This work further compares the effects of single rescattering events with those of multiple rescatterings, as particles travel the nuclear volume. We estimate the dominant source of the uncertainties associated with our formalism by varying the scale of the atomic physics where the screening of the electric field of the nucleus happens. This calculation not only contributes to the understanding of QED nuclear medium effects, but also offers a path to a more precise extraction of the process-independent nonperturbative structure of nuclei.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Medium induced transverse momentum broadening in hard processes

In this study, using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related P T broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium P T broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Influence of phase connectivity on the relationship among capillary pressure, fluid saturation, and interfacial area in two-fluid-phase porous medium systems

Here, multiphase flow in porous medium systems is typically modeled using continuum mechanical representations at the macroscale in terms of averaged quantities. These models require closure relations to produce solvable forms. One of these required closure relations is an expression relating fluid pressures, fluid saturations, and, in some cases, the interfacial area between the fluid phases, and the Euler characteristic. An unresolved question is whether the inclusion of these additional morphological and topological measures can lead to a non-hysteretic closure relation compared to the hysteretic forms that are used in traditional models, which typically do not include interfacial areas, or the Euler characteristic. We develop a lattice-Boltzmann (LB) simulation approach to investigate the equilibrium states of a two-fluid-phase porous medium system, which include disconnected now- wetting phase features. The proposed approach is applied to a synthetic medium consisting of 1,964 spheres arranged in a random, non-overlapping, close-packed manner, yielding a total of 42,908 different equilibrium points. This information is evaluated using a generalized additive modeling approach to determine if a unique function from this family exists, which can explain the data. The variance of various model estimates is computed, and we conclude that, except for the limiting behavior close to a single fluid regime, capillary pressure can be expressed as a deterministic and non-hysteretic function of fluid saturation, interfacial area between the fluid phases, and the Euler characteristic. This work is unique in the methods employed, the size of the data set, the resolution in space and time, the true equilibrium nature of the data, the parameterizations investigated, and the broad set of functions examined. The conclusion of essentially non-hysteretic behavior provides support for an evolving class of two-fluid-phase flow in porous medium systems models.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Medium Voltage Converter Inductor Insulation Design Considering Grid Insulation Requirements

Medium voltage SiC devices facilitate direct (without 50/60 Hz transformer) connection of the power electronics converter to the medium voltage grid using simple topology. Compared to the insulation design of medium voltage inductors that have been widely used in the power system, the insulation design of directly connected medium voltage converter filter inductors has more challenges. Although some works has been done discussing that, the grid insulation requirements on converter filter inductors are rarely discussed. This paper introduces the insulation design of a grid-side filter inductor for a 13.8 kV power conditioning system converter. The grid insulation requirements, including the short-duration power frequency overvoltage and the lightning impulse voltage, are considered in the design. To meet the requirements, the layer-to-layer insulation, winding-to-core/ground insulation, the air gap discharge between the winding and the core, as well as the local electrical field have been taken into consideration. Experimental tests are provided to validate the design.

Li, Haiguo↗
DOE OSTI2022

Drying of a Fully Saturated Porous Medium With Excess Water Layers: A Numerical Study

Abstract Drying of moist porous media can be very energy inefficient. For example, in the pulp and paper industry, paper drying consumes more than two-thirds of the total energy used in paper machines. Novel drying technologies can decrease the energy used for drying and lessen the manufacturing processes' carbon footprint. Developing next-generation drying technologies to dry moist porous media may require an understanding of removing moisture from a fully saturated porous material with excess water. This paper provides a fundamental understanding of heat and mass transfer in a fully saturated porous medium with excess water. This is relevant, for example, in drying tissue as well as pulp or paper for the purpose of thermal insulation where pressing is preferred to be avoided to overcome the reduction in the sheet thickness. For this purpose, a theoretical drying model is developed where the porous medium corresponds to paper and is assumed to be sandwiched between two excess-water layers (bottom and top). The conjugate model consists of energy and mass conservation equations for each layer. The model is validated with corresponding experimental data. In the model, the thickness of each water layer is calculated as a function of drying time based on local temperature and total moisture content. The numerical model is transient and one-dimensional in space (i.e., in the thickness direction). This paper demonstrates the governing equations, boundary conditions, and results when the saturated porous medium with water layers is heated from one side. Moisture and temperature profiles are estimated in the thickness direction of the porous medium as it dries.

Engineering↗