Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “TITAN”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Titan Turtle: NIAC Phase II Design for a Submersible Vehicle for Titan Exploration

Conceptual designs for a submersible vehicle for exploration of the hydrocarbon seas of Saturn’s moon Titan were done by the NASA Glenn COMPASS systems engineering team, as part of the NASA’s Innovative Advanced Concepts (NIAC) program. The efforts investigated what approaches and technologies would allow exploration below the surface of the low temperature (–180 °C) hydrocarbon seas of Titan. The Phase-II design refined the design concepts, looking at a smaller design supported by an orbital relay, the “Titan Turtle”. The phase-II project resulted in a smaller vehicle using an orbiter supported relay/navigation link to eliminate the requirement for a large phased-array antenna. Eliminating the DTE communications requirement also reduced the associated high power required by the communications system.

Steven R Oleson↗
NASA NTRSDate not supplied

Titan Turtle: NIAC Phase II Design for a Submersible Vehicle for Titan Exploration

Conceptual designs for a submersible vehicle for exploration of the hydrocarbon seas of Saturn’s moon Titan were done by the NASA Glenn COMPASS systems engineering team, as part of the NASA’s Innovative Advanced Concepts (NIAC) program. The efforts investigated what approaches and technologies would allow exploration below the surface of the low temperature (–180 °C) hydrocarbon seas of Titan. The Phase-II design refined the design concepts, looking at a smaller design supported by an orbital relay, the “Titan Turtle”. The phase-II project resulted in a smaller vehicle using an orbiter supported relay/navigation link to eliminate the requirement for a large phased-array antenna. Eliminating the DTE communications requirement also reduced the associated high power required by the communications system.

Lunar and Planetary Scientific Exploration↗
DOE OSTI2015

Physical properties and electronic structure of a new barium titanate suboxide Ba{sub 1+δ}Ti{sub 13−δ}O{sub 12} (δ = 0.11)

The structure, transport, thermodynamic properties, x-ray absorption spectra (XAS), and electronic structure of a new barium titanate suboxide, Ba{sub 1+δ}Ti{sub 13−δ}O{sub 12} (δ = 0.11), are reported. It is a paramagnetic poor metal with hole carriers dominating the transport. Fermi liquid behavior appears at low temperature. The oxidization state of Ti obtained by the XAS is consistent with the metallic Ti{sup 2+} state. Local density approximation band structure calculations reveal the material is near the Van Hove singularity. The pseudogap behavior in the Ti-d band and the strong hybridization between the Ti-d and O-p orbitals reflect the characteristics of the building blocks of the Ti{sub 13} semi-cluster and the TiO{sub 4} quasi-squares, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Small hole polarons in rare-earth titanates

In this study, we investigate the behavior of hole polarons in rare-earth titanates by combining optical conductivity measurements with first-principles hybrid density functional calculations. Sr-doped GdTiO 3 (Gd 1-x Sr x TiO 3 ) was grown by molecular beam epitaxy. We show that a feature in the optical conductivity that was previously identified with the Mott-Hubbard gap is actually associated with the excitation of a small polaron. The assignment is based on an excellent match between the experimental spectra and first-principles calculations for polaron excitation mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Probing the thermal Hall effect using miniature capacitive strontium titanate thermometry

The thermal Hall effect is the thermal analog of the electrical Hall effect. Rarely observed in normal metals, thermal Hall signals have been argued to be a key property for a number of strongly correlated materials, such as high temperature superconductors, correlated topological insulators, and quantum magnets. The observation of the thermal Hall effect requires precise measurement of temperature in intense magnetic fields. Particularly at low temperature, resistive thermometers have a strong dependence on field, which makes them unsuitable for this purpose. We have created capacitive thermometers which instead measure the dielectric constant of strontium titanate (SrTiO 3 ). SrTiO 3 approaches a ferroelectric transition, causing its dielectric constant to increase by a few orders of magnitude at low temperature. As a result, these thermometers are very sensitive at low temperature while having very little dependence on the applied magnetic field, making them ideal for thermal Hall measurements. Here, we demonstrate this method by making measurements of the thermal Hall effect in Bismuth in magnetic fields of up to 10 T.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Initial Stages of Growth of Barium Zirconate Titanate and Barium Stannate Titanate Films on Single-Crystal Sapphire and Silicon Carbide

The initial stages of growth of barium zirconate titanate and barium stannate titanate ferroelectric films on single-crystal sapphire and silicon carbide are studied for the first time. The choice of substrates is dictated by the possibility of using such structures in ultra-high frequency devices. The growth of discontinuous BaZr{sub x}Ti{sub 1–x}O{sub 3} films is found to be mediated by the gas phase mass transport mechanism in the studied temperature range. For deposition of BaSn{sub x}Ti{sub 1–x}O{sub 3} films, the mechanism of mass transport switches at ~800°C from surface diffusion to gas phase diffusion; also, the films deposited on sapphire and silicon carbide have considerably different elemental composition. The formation of an intermediate SiO{sub 2} layer is noted on silicon carbide during the growth of oxide films on this substrate, its thickness depending on the deposition temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Fatigue of extracted lead zirconate titanate multilayer actuators under unipolar high field electric cycling

Testing of large prototype lead zirconate titanate (PZT) stacks presents substantial technical challenges to electronic testing systems, so an alternative approach that uses subunits extracted from prototypes has been pursued. Extracted 10-layer and 20-layer plate specimens were subjected to an electric cycle test under an electric field of 3.0/0.0 kV/mm, 100 Hz to 10{sup 8} cycles. The effects of measurement field level and stack size (number of PZT layers) on the fatigue responses of piezoelectric and dielectric coefficients were observed. On-line monitoring permitted examination of the fatigue response of the PZT stacks. The fatigue rate (based on on-line monitoring) and the fatigue index (based on the conductance spectrum from impedance measurement or small signal measurement) were developed to quantify the fatigue status of the PZT stacks. The controlling fatigue mechanism was analyzed against the fatigue observations. The data presented can serve as input to design optimization of PZT stacks and to operation optimization in critical applications, such as piezoelectric fuel injectors in heavy-duty diesel engines.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

A Big Data Analytics Framework for HPC Log Data: Three Case Studies Using the Titan Supercomputer Log

Reliability, availability and serviceability (RAS) logs of high performance computing (HPC) resources, when closely investigated in spatial and temporal dimensions, can provide invaluable information regarding system status, performance, and resource utilization. These data are often generated from multiple logging systems and sensors that cover many components of the system. The analysis of these data for finding persistent temporal and spatial insights faces two main difficulties: the volume of RAS logs makes manual inspection difficult and the unstructured nature and unique properties of log data produced by each subsystem adds another dimension of difficulty in identifying implicit correlation among recorded events. To address these issues, we recently developed a multi-user Big Data analytics framework for HPC log data at Oak Ridge National Laboratory (ORNL). This paper introduces three in-progress data analytics projects that leverage this framework to assess system status, mine event patterns, and study correlations between user applications and system events. We describe the motivation of each project and detail their workflows using three years of log data collected from ORNL's Titan supercomputer.

Park, Byung↗
DOE OSTI2017

Formation of sodium bismuth titanate-barium titanate during solid-state synthesis

Phase formation of sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 or NBT) and its solid solution with barium titanate (BaTiO 3 or BT) during the calcination process is studied using in situ high-temperature diffraction. The reactant powders were mixed and heated to 1000°C, while X-ray diffraction patterns were recorded continuously. Phase evolutions from starting materials to final perovskite products are observed, and different transient phases are identified. The formation mechanism of NBT and NBT–xBT perovskite structures is discussed, and a reaction sequence is suggested based on the observations. The in situ study leads to a new processing approach, which is the use of nano-TiO 2 , and gives insights to the particle size effect for solid-state synthesis products. Lastly, it was found that the use of nano-TiO 2 as reactant powder accelerates the synthesis process, decreases the formation of transient phases, and helps to obtain phase-pure products using a lower thermal budget.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A layered nonstoichiometric lepidocrocite-type sodium titanate anode material for sodium-ion batteries

A lepidocrocite-structured sodium titanate prepared by ion-exchange of a Cs-containing precursor shows promise as an anode material for sodium ion batteries, with a discharge capacity of up to 229 mAh g -1 at an average potential of about 0.6 V vs. Na + /Na. Titanium vacancies in the metal oxide layers provide additional sites for sodium intercalation in addition to interlayer sites, which accounts for the higher capacity compared to other previously reported lepidocrocite-structured titanates. By screening a series of electrolyte formulations and binders, we were able to improve the first-cycle coulombic efficiency to 81.8% and 94.7% respectively using CMC/SBR-based and binder-free electrodes in ether electrolytes. Finally, the electrochemical consequences of short-term air-exposure on the electrodes are also discussed.

25 ENERGY STORAGE↗
DOE OSTI2015

P-type conductivity in annealed strontium titanate

Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

36 MATERIALS SCIENCE↗
NASA NTRS1991

Titan's atmosphere from Voyager infrared observations. III - Vertical contributions of hydrocarbons and nitriles near Titan's north pole

Voyager 1 IR spectra have been used to infer the Titan north polar region minor stratospheric constituents' temperature structure and vertical distribution. The mixing ratios of the species C4H2, C2H6, C3H4, HCN, HC3N, and C2N2 increase with altitude, implying upper stratosphere (and higher) formation regions. When compared with abundances obtained near the equator, it is found that the HC3N and C2N2 nitriles, together with such hydrocarbons as C2H4, C3H4, and C4H2, are substantially enhanced over the north polar region. A factor-of-2 (minimum) depletion of CO2 relative to the equator is noted; it is judged that current photochemical models are inadequate bases for interpretation of these observations.

Coustenis, A.↗