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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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

High throughput semiconductor deposition system

A reactor for growing or depositing semiconductor films or devices. The reactor may be designed for inline production of III-V materials grown by hydride vapor phase epitaxy (HVPE). The operating principles of the HVPE reactor can be used to provide a completely or partially inline reactor for many different materials. An exemplary design of the reactor is shown in the attached drawings. In some instances, all or many of the pieces of the reactor formed of quartz, such as welded quartz tubing, while other reactors are made from metal with appropriate corrosion resistant coatings such as quartz or other materials, e.g., corrosion resistant material, or stainless steel tubing or pipes may be used with a corrosion resistant material useful with HVPE-type reactants and gases. Using HVPE in the reactor allows use of lower-cost precursors at higher deposition rates such as in the range of 1 to 5 .mu.m/minute.

36 MATERIALS SCIENCE↗
DOE OSTI2019

High throughput semiconductor deposition system

A reactor for growing or depositing semiconductor films or devices. The reactor may be designed for inline production of III-V materials grown by hydride vapor phase epitaxy (HVPE). The operating principles of the HVPE reactor can be used to provide a completely or partially inline reactor for many different materials. An exemplary design of the reactor is shown in the attached drawings. In some instances, all or many of the pieces of the reactor formed of quartz, such as welded quartz tubing, while other reactors are made from metal with appropriate corrosion resistant coatings such as quartz or other materials, e.g., corrosion resistant material, or stainless steel tubing or pipes may be used with a corrosion resistant material useful with HVPE-type reactants and gases. Using HVPE in the reactor allows use of lower-cost precursors at higher deposition rates such as in the range of 1 to 5 .mu.m/minute.

Young, David L.↗
NASA NTRS2013

Unibody Composite Pressurized Structure

An integrated, generic unibody composite pressurized structure (UCPS) combined with a positive expulsion device (PED), consisting of an elastomeric bladder for monopropellant hydrazine, has been quasi-standardized for spacecraft use. The combination functions as an all-composite, non-metallic, propellant tank with bladder. The integrated UCPS combines several previous innovations - specifically, the linerless, all-composite cryogenic tank technology; all-composite boss; resin formulation; and integrated stringer system. The innovation combines the UCPS with an integrated propellant management device (PMD), the PED or bladder, to create an entirely unique system for in-space use. The UCPS is a pressure vessel that incorporates skirts, stringers, and other structures so that it is both an in-space hydrazine tank, and also a structural support system for a spacecraft in a single, all-composite unit. This innovation builds on the progress in the development of a previous SBIR (Small Business Innovation Research) Phase I with Glenn Research Center and an SBIR III with Johnson Space Center that included the fabrication of two 42-in. (≈107-cm) diameter all-composite cryogenic (LOX and liquid methane) UCPS test tanks for a lunar lander. This Phase II provides hydra zine compatibility testing of the elastomeric bladder, a see-through PED to validate the expulsion process and model, and a complete UCPS-based PED with stringers and skirts that will be used to conduct initial qualification and expulsion tests. This extends the UCPS technology to include hydrazine-based, in-space pro - pulsion applications and can also be used for electric propulsion. This innovation creates a system that, in comparison to the traditional approach, is lower in weight, cost, volume, and production time; is stronger; and is capable of much higher pressures. It also has fewer failure modes, and is applicable to both chemical and electric propulsion systems.

Rufer, Markus↗
DOE OSTI2015

RE-VISIT OF HST FUV OBSERVATIONS OF THE HOT-JUPITER SYSTEM HD 209458: NO Si iii DETECTION AND THE NEED FOR COS TRANSIT OBSERVATIONS

The discovery of O i atoms and C ii ions in the upper atmosphere of HD 209458b, made with the Hubble Space Telescope Imaging Spectrograph (STIS) using the G140L grating, showed that these heavy species fill an area comparable to the planet’s Roche lobe. The derived ∼10% transit absorption depths require super-thermal processes and/or supersolar abundances. From subsequent Cosmic Origins Spectrograph (COS) observations, C ii absorption was reported with tentative velocity signatures, and absorption by Si iii ions was also claimed in disagreement with a negative STIS G140L detection. Here, we revisit the COS data set showing a severe limitation in the published results from having contrasted the in-transit spectrum against a stellar spectrum averaged from separate observations, at planetary phases 0.27, 0.72, and 0.49. We find variable stellar Si iii and C ii emissions that were significantly depressed not only during transit but also at phase 0.27 compared to phases 0.72 and 0.49. Their respective off-transit 7.5% and 3.1% flux variations are large compared to their reported 8.2 ± 1.4% and 7.8 ± 1.3% transit absorptions. Significant variations also appear in the stellar line shapes, questioning reported velocity signatures. We furthermore present archive STIS G140M transit data consistent with no Si iii absorption, with a negative result of 1.7 ± 18.7 including ∼15% variability. Silicon may still be present at lower ionization states, in parallel with the recent detection of extended magnesium, as Mg i atoms. In this frame, the firm detection of O i and C ii implying solar or supersolar abundances contradicts the recent inference of potential 20–125× subsolar metallicity for HD 209458b.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Period–luminosity relations derived from the OGLE-III fundamental mode Cepheids. II. The small magellanic cloud Cepheids

In this paper we present multi-band period–luminosity (P–L) relations for fundamental mode Cepheids in the SMC. The optical VI-band mean magnitudes for these SMC Cepheids were taken from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III) catalog. We also matched the OGLE-III SMC Cepheids to 2MASS and SAGE-SMC catalog to derive mean magnitudes in the JHK-bands and the four Spitzer IRAC bands, respectively. All photometry was corrected for extinction by adopting Zaritsky’s extinction map. Cepheids with periods smaller than ∼2.5 days were removed from the sample. In addition to the extinction corrected P–L relations in nine filters from optical to infrared, we also derived the extinction-free Wesenheit function for these Cepheids. We tested the nonlinearity of these SMC P–L relations (except the 8.0 μm-band P–L relation) at 10 days: none of the P–L relations show statistically significant evidence of nonlinearity. When compared to the P–L relations in the LMC, the t-test results revealed that there is a difference between the SMC/LMC P–L slopes only in the V- and J-band. Further, we found excellent agreement between the SMC/LMC Wesenheit P–L slope. The difference in LMC and SMC Period–Wesenheit relation LMC and SMC zero points was found to be Δμ=0.483±0.015 mag. This amounts to a difference in distance modulus between the LMC and SMC.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Strength mechanisms and tunability in Al-Ce-Mg ternary alloys enabled by additive manufacturing

Al-Ce-based alloys are promising candidates for additive manufacturing (AM) due to their hot-cracking resistance and because they do not require heat treatment to obtain precipitation strengthening. Rapid solidification rates enabled by AM methods can lead to enhanced mechanical properties; however, the strengthening mechanisms over large composition ranges were unclear. Here, combinatorial synthesis by directed-energy deposition (DED) and hardness measurements were used to rapidly map the composition-dependent strength of the ternary Al-Ce-Mg system. Tensile testing and microstructure characterization of selected compositions were performed to elucidate the compositional dependence of the strengthening mechanisms. Al 11 Ce 3 precipitates were present in all cases, and the maximum hardness (1.25 GPa) was measured for the Al-8Ce-10Mg composition. A combination of (i) Hall-Petch strengthening, based on the FCC-matrix-phase cell size; (ii) particle strengthening, based on Al 11 Ce 3 volume fraction and size; and (iii) solid-solution strengthening, based on Mg composition of the matrix phase, were used to account for the measured strengths. Vickers hardness is shown to correlate well with ultimate tensile strength in these alloys, highlighting the value of surface-based techniques for rapid screening.

36 MATERIALS SCIENCE↗
NASA NTRS1986

Phase transitions and convection in icy satellites

The effects of solid-solid phase changes on subsolidus convection in the large icy moons of the outer solar system are considered. Phase transitions affect convection via processes that distort the phase change boundary and/or influence buoyancy through thermal expansion. Linear stability analyses are carried out for ice layers with a phase change at the midplane. Two exothermic phase transitions (ice I - ice II, ice VI - ice VIII) and two endothermic transitions (ice I - ice III, ice II - ice V) are considered. For the exothermic cases, the phase change can either impede or enhance whole-layer convection. For the endothermic cases, the phse change always inhibits whole-layer convective overturn and tends to enforce two-layer convection. These results play some constraints on possible models of icy satellite evolution and structure.

Bercovici, D.↗
NASA NTRSDate not supplied

Mitigation of High Lateral Asymmetry Rates Due to Loss of a Cruise Motor on the X-57 Mod III Aircraft

The X-57 Mod III aircraft utilizes wingtip electric motors to generate thrust. The potential benefit of wingtip propulsion is a reduction in induced drag because wingtip vortices are interrupted. Wingtip propulsors, however, pose the risk of dangerous thrust asymmetry if one of the motors abruptly stops producing full thrust. This paper examines the effects of a full-power, single-motor failure at various phases of flight for the X-57 Mod III aircraft design by way of piloted-in-the-loop simulations conducted by two National Aeronautics and Space Administration test pilots. After determining that a failure during takeoff potentially poses the highest risk of catastrophic consequences, possible mitigations to the failure were explored and evaluated through pilot simulation data, Cooper-Harper ratings, and pilot comments. The preferred mitigation was found to be an automated power reduction system that allowed for a lower pilot workload and quick reduction of the asymmetric thrust.

Ryan Wallace↗
DOE OSTI2015

Multi-scale Material Parameter Identification Using LS-DYNA® and LS-OPT®

Ever-tightening regulations on fuel economy and carbon emissions demand continual innovation in finding ways for reducing vehicle mass. Classical methods for computational mass reduction include sizing, shape and topology optimization. One of the few remaining options for weight reduction can be found in materials engineering and material design optimization. Apart from considering different types of materials by adding material diversity, an appealing option in automotive design is to engineer steel alloys for the purpose of reducing thickness while retaining sufficient strength and ductility required for durability and safety. Such a project was proposed and is currently being executed under the auspices of the United States Automotive Materials Partnership (USAMP) funded by the Department of Energy. Under this program, new steel alloys (Third Generation Advanced High Strength Steel or 3GAHSS) are being designed, tested and integrated with the remaining design variables of a benchmark vehicle Finite Element model. In this project the principal phases identified are (i) material identification, (ii) formability optimization and (iii) multi-disciplinary vehicle optimization. This paper serves as an introduction to the LS-OPT methodology and therefore mainly focuses on the first phase, namely an approach to integrate material identification using material models of different length scales. For this purpose, a multi-scale material identification strategy, consisting of a Crystal Plasticity (CP) material model and a Homogenized State Variable (SV) model, is discussed and demonstrated. The paper concludes with proposals for integrating the multi-scale methodology into the overall vehicle design.

36 MATERIALS SCIENCE↗
DOE OSTI2019

In-situ monitoring of seeded and unseeded stage III corrosion using Raman spectroscopy

Abstract Stage III glass dissolution, the occasionally observed tendency for accelerated aqueous corrosion after extensive time spent at low reaction rates, is a major area of technical uncertainty in long-term glass performance modeling for vitreous nuclear waste forms. Stage III dissolution behavior is thought to be caused by the precipitation of zeolite phases that lower the activity of the rate-controlling orthosilicic acid ion and cause the acceleration of glass dissolution. The uncertainty lies mainly in a poor understanding of the growth kinetics of these key crystalline phases. It is particularly important to understand the impact of temperature and pH conditions on Stage III behavior. Accurate analysis of this phenomenon is complicated by the typically very long (e.g., years), and variable length of the induction period preceding the onset of Stage III behavior. In this study of a high-sodium aluminoborosilicate glass, we demonstrate the ability to initiate the onset of Stage III behavior in a controllable fashion so as to both reduce the time delay of the incubation period, and to also be able to initiate Stage III dissolution in controlled conditions. In this case, we demonstrate that Stage III glass corrosion behavior is possible at 70 °C, a lower temperature than previously observed (90 °C), even in an unseeded experiment. We confirm, through a comparison study, that seeded and unseeded Stage III corrosion rates are equivalent. This enables wide-scale testing of Stage III corrosion rates for many glass compositions in relatively short times through this technique. We also report further development of the use of in situ Raman spectroscopy monitoring of boron concentration and pH through simple and chemometric analysis methods.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Probing the fatigue enhancement in a thermally aged cast duplex stainless steel by in situ neutron diffraction

After long-term thermal aging at 400 °C for 3000 h and 10,000 h, a cast duplex stainless steel exhibits promoted fatigue performance, including enhanced three-stage cyclic hardening and prolonged fatigue life. Utilizing in situ neutron diffraction, the phase-specific stresses are resolved, and their evolutions over entire fatigue cycling reveal the underlying mechanisms of the fatigue enhancement. It is found that the ferrite phase bears a much higher stress than the austenite matrix under both as-received and aged conditions. The enhanced cyclic hardening in Stage I is attributed to the strengthening of both phases due to thermal aging, while the enhancement in Stage III results from the martensitic transformation induced strengthening. The fatigue life is prolonged thanks to the cyclic hardening and the delay of martensitic transformation in the austenite phase after thermal aging.

Yu, Dunji↗
DOE OSTI2023

Controllable topological insulator phases in litharge-phase InBi monolayer

Despite recent advances of layered square-net topological material models that possess ideal semimetallic electronic structures and promising potential in material applications, the identification of experimentally accessible two-dimensional square-net materials with related topological properties has proven challenging. Due to the highly tunable physical and topological properties of III-V semiconductors, we revisit the class of III-V materials and observe that the litharge-phase InBi is a layered square-net material and can be exfoliated into the InBi monolayer. We present a comprehensive first-principles study of the energy landscape of the InBi monolayer. We identify a paraelastic phase and three ferroelastic phases and study their topological properties. Specifically, we show that the paraelastic InBi monolayer is a trivial insulator due to the orbital-ordering-induced band inversion occurring between states with the same parity. Substituting one Bi atom per cell with another V-group element (N, P, As) or applying an electric field that breaks the inversion symmetry and changes the orbital onsite energy, the paraelastic InBi monolayer can be driven into the topological insulator phase. Furthermore, one of the ferroelastic phases of pure InBi, which can be obtained by gently straining the paraelastic phase, also possesses such topological insulating properties. Furthermore, these results provide several experimentally accessible routes to tune the nontrivial topology in the InBi monolayer, including creating heterostructures with piezoelectric or ferroelectric substrates and applying mechanical strain, making the InBi monolayer an ideal platform to study the interplay of reduced dimensionality, square-net chemical bonding networks, and band topology.

2-dimensional systems↗
NASA NTRS1994

Coherent-phase or random-phase acceleration of electron beams in solar flares

Time structures of electron beam signatures at radio wavelengths are investigated to probe correlated versus random behavior in solar flares. In particular we address the issue whether acceleration and injection of electron beams is coherently modulated by a single source, or whether the injection is driven by a stochastic (possibly spatially fragmented) process. We analyze a total of approximately = 6000 type III bursts observed by Ikarus (Zurich) in the frequency range of 100-500 MHz, during 359 solar flares with simultaneous greater than or = 25 keV hard X-ray emission, in the years 1890-1983. In 155 flares we find a total of 260 continuous type III groups, with an average number of 13 +/- 9 bursts per group, a mean duration of D = 12 +/- 14 s, a mean period of P = 2.0 +/- 1.2 s, with the highest burst rate at a frequency of nu = 310 +/- 120 MHz. Pulse periods have been measured between 0.5 and 10 s, and can be described by an exponential distribution, i.e., N(P) varies as e (exp -P/1.0s). The period shows a frequency dependence of P(nu)=46(exp-0.6)(sub MHz)s for different flares, but is invariant during a particular flare. We measure the mean period P and its standard deviation sigma (sub p) in each type III group, and quantify the degree of periodicity (or phase-coherence) by the dimensionless parameter sigma (sub p)P. The representative sample of 260 type III burst groups shows a mean periodicity of sigma (sub p/P) = 0.37 +/- 0.12, while Monte Carlo simulations of an equivalent set of truly random time series show a distinctly different value of sigma (sub p)P = 0.93 +/- 0.26. This result indicates that the injection of electron beams is coherently modulated by a particle acceleration source which is either compact or has a global organization on a timescale of seconds, in contrast to an incoherent acceleration source, which is stochastic either in time or space. We discuss the constraints on the size of the acceleration region resulting from electron beam propagation delays and from Alfvenic synchronization during a pulse period. We discuss two periodic preocesses in flares, which potentially control quasi-periodic particle acceleration: (1) MHD oscillations, and (2) current sheets with oscillatory dynamics.

Aschwanden, Markus J.↗
NASA NTRS2012

The Operational MODIS Cloud Optical and Microphysical Property Product: Overview of the Collection 6 Algorithm and Preliminary Results

Operational Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals of cloud optical and microphysical properties (part of the archived products MOD06 and MYD06, for MODIS Terra and Aqua, respectively) are currently being reprocessed along with other MODIS Atmosphere Team products. The latest "Collection 6" processing stream, which is expected to begin production by summer 2012, includes updates to the previous cloud retrieval algorithm along with new capabilities. The 1 km retrievals, based on well-known solar reflectance techniques, include cloud optical thickness, effective particle radius, and water path, as well as thermodynamic phase derived from a combination of solar and infrared tests. Being both global and of high spatial resolution requires an algorithm that is computationally efficient and can perform over all surface types. Collection 6 additions and enhancements include: (i) absolute effective particle radius retrievals derived separately from the 1.6 and 3.7 !-lm bands (instead of differences relative to the standard 2.1 !-lm retrieval), (ii) comprehensive look-up tables for cloud reflectance and emissivity (no asymptotic theory) with a wind-speed interpolated Cox-Munk BRDF for ocean surfaces, (iii) retrievals for both liquid water and ice phases for each pixel, and a subsequent determination of the phase based, in part, on effective radius retrieval outcomes for the two phases, (iv) new ice cloud radiative models using roughened particles with a specified habit, (v) updated spatially-complete global spectral surface albedo maps derived from MODIS Collection 5, (vi) enhanced pixel-level uncertainty calculations incorporating additional radiative error sources including the MODIS L1 B uncertainty index for assessing band and scene-dependent radiometric uncertainties, (v) and use of a new 1 km cloud top pressure/temperature algorithm (also part of MOD06) for atmospheric corrections and low cloud non-unity emissivity temperature adjustments.

Platnick, Steven↗
DOE OSTI2017

An Interdisciplinary View of Interfaces: Perspectives Regarding Emergent Phase Formation

A perspective on emergent phase formation is presented using an interdisciplinary approach gained by working at the “interface” between diverse application areas, including solid oxide fuel cells (SOFCs) and ionic membrane systems, solid state lithium batteries, and ceramics for nuclear waste immobilization. The grain boundary interfacial characteristics of model single-phase materials in these application areas, including (i) CeO2, (ii) Li7La3Zr2O12 (LLZO), and (iii) hollandite of the form BaxCsyGa2x+yTi8-2x-yO16, as well as the potential for emergent phase formation in composite systems, are discussed. The potential physical properties resulting from emergent phase structure and distribution are discussed, including an overview of existing three-dimensional (3D) imaging techniques recently used for characterization. Finally, an approach for thermodynamic characterization of emergent phases based on melt solution calorimetry is outlined, which may be used to predict the energy landscape including phase formation and stability of complex multiphase systems.

25 ENERGY STORAGE↗
NASA NTRS1985

Solar flare development during the impulsive phase as deduced from correlated radio and hard X-ray observations

A correlative study of metric type III/V bursts and hard X-ray events during the preflash and the impulsive phases of solar flares is presented. A total of 55 groups of type III bursts were observed with the Nancay radiospectrograph, and 32 of these were associated with hard X-ray bursts detected with instruments on ISEE 3, SMM, or both. X-ray bursts associated with type III or U bursts, and type V continuum emission lasting less than 10 s are relatively small, with peak fluxes at 30 keV of not more than 1 photon/sq cm per sec per keV. X-ray bursts associated with type III bursts and continuum emission lasting longer than 30 s are considerably more intense, with peak fluxes at 30 keV exceeding 1 photon/sq cm per sec per keV and spectra extending to not less than 100 keV. For these latter events, type III emission was observed at 169 MHz with the Nancay radioheliograph from several locations during the preflash phase. At the time of the rapid increase in the hard X-ray flux, a new source appeared at 169 MHz and proceeded to fluctuate in phase with one of the original sources that brightened at the same time. This type of behavior, observed in 13 flares, is interpreted as being caused by the rapid interaction of two or more magnetic structures giving rise to the impulsive phase of the flare.

Raoult, A.↗
DOE OSTI2013

THE MAGELLANIC QUASARS SURVEY. III. SPECTROSCOPIC CONFIRMATION OF 758 ACTIVE GALACTIC NUCLEI BEHIND THE MAGELLANIC CLOUDS

The Magellanic Quasars Survey (MQS) has now increased the number of quasars known behind the Magellanic Clouds by almost an order of magnitude. All survey fields in the Large Magellanic Cloud (LMC) and 70% of those in the Small Magellanic Cloud (SMC) have been observed. The targets were selected from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III) based on their optical variability, mid-IR, and/or X-ray properties. We spectroscopically confirmed 758 quasars (565 in the LMC and 193 in the SMC) behind the clouds, of which 94% (527 in the LMC and 186 in the SMC) are newly identified. The MQS quasars have long-term (12 yr and growing for OGLE), high-cadence light curves, enabling unprecedented variability studies of quasars. The MQS quasars also provide a dense reference grid for measuring both the internal and bulk proper motions of the clouds, and 50 quasars are bright enough (I ∼< 18 mag) for absorption studies of the interstellar/intergalactic medium of the clouds.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Water-soluble Schiff base-actinyl complexes and their effect on the solvent extraction of f-elements

Conventional solvent extraction of selected f-element cations by bis(2-ethylhexyl)phosphoric acid (HDEHP) yields increased extraction from aqueous to organic solution along the series Np(V) < Cm(III) < Eu(III) < U(VI), with distribution ratios all within two orders of magnitude. However, in the presence of the water-soluble tetradentate Schiff base (N,N'-bis(5-sulfonatosalicylidene)-ethylenediamine or H 2 salenSO 3 ), selective complexation of the two actinyl cations (Np(V) and U(VI)) resulted in an extraction order of Np(V) < U(VI) << Eu(III) < Cm(III). The extraction of neither Cm(III) or Eu(III) by HDEHP are significantly impacted by the presence of the aqueous phase Schiff base. Despite observed hydrolytic decomposition of H 2 salenSO 3 in aqueous solutions, the calculated high conditional stability constant (β 11 = 26) for the complex [UO 2 (salenSO 3 )] 2- demonstrates its capacity for aqueous hold-back of U(VI). UV-visible-NIR spectroscopy of solutions prepared with a Np(VI) stock and H 2 salenSO 3 suggest that reduction of Np(VI) to Np(V) by the ligand was rapid, resulting in a pentavalent Np complex that was substantially retained in the aqueous phase. Lastly, results from 1 H NMR of aqueous solutions of H 2 salenSO 3 with U(VI) and La(III), Eu(III), and Lu(III) provides additional evidence that the ligand readily chelates U(VI), but has only weak interactions with trivalent lanthanide ions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗