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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Search for J / ψ weak decays containing a D meson

Using a sample of about 10 billion J / ψ events with the BESIII detector, we search for the weak decays of J / ψ → D ¯ 0 π 0 + c . c . , J / ψ → D ¯ 0 η + c . c . , J / ψ → D ¯ 0 ρ 0 + c . c . , J / ψ → D − π + + c . c . , and J / ψ → D − ρ + + c . c . . Since no significant signal is observed, we set the upper limits of the branching fractions of these decays to be B ( J / ψ → D ¯ 0 π 0 + c . c . ) < 4.7 × 10 − 7 , B ( J / ψ → D ¯ 0 η + c . c . ) < 6.8 × 10 − 7 , B ( J / ψ → D ¯ 0 ρ 0 + c . c . ) < 5.2 × 10 − 7 , B ( J / ψ → D − π + + c . c . ) < 7.0 × 10 − 8 , and B ( J / ψ → D − ρ + + c . c . ) < 6.0 × 10 − 7 at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2021

Structural and electronic properties of the first iridium containing mixed B-site spinel oxide: Cu [ Ir 1.5 Cu 0.5 ] O 4

Geometrically frustrated systems populated with large spin-orbit coupled ions are an ideal setting for the exploration of novel exotic states of matter. In this study we present an example of iridium on a mixed B-site spinel oxide structure: Cu [ Ir 1.498 ( 2 ) Cu 0.502 ( 2 ) ] O 4 . Synchrotron XRD refinements reveal a face-centered-cubic structure with space group F d 3 ¯ m and mixed Cu-Ir site disorder within the B 2 O 4 rocksalt substructure. Electrical properties reveal a metallic state within the 50–600-K range with a Kondo effect at T < 50 K . X-ray absorption spectroscopy (XAS) measurements show a mixed Cu 1 + / 2 + and Ir 3 + / 4 + charge partitioned picture, which suggests a metallic/band description with reduced on-site Coulomb interactions. Spin-glass-like freezing is seen at T g = 49 K , and the hysteresis behavior for T > T g resembles that of a strongly frustrated magnet. DFT calculations show sizable hybridization between the Cu 3 d and Ir 5 d states with an effective mixed Ir 3 + / 4 + charge partitioned picture, supporting the electronic and XAS results.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Study of a High-speed Outer Rotor Burst Containing Enclosure

The increasing demand for high-speed electric machines in many applications pushes the development of high-power density electric motors. Outer rotor motors, which can be designed with a larger airgap diameter than inner rotor motors for the same overall diameter and, therefore, provide higher torque, distinguish themselves in space-constrained but high torque applications. However, increasing the motor speed and diameter results in significant centrifugal loads for the outer rotor motor due to its higher airgap diameter. Additional attention must be paid at the design stage to consider the extreme situation of possible mechanical failure, such as the sudden burst of the high-speed rotating parts in the motor, and measures must be taken to prevent their damage to other system components in advance. Through the finite element dynamic impact analysis, we studied the damage caused by broken parts on the inner wall of the electric motor housing when the motor rotates at 20,000 RPM. The proposed method is expected to provide reasonable recommendations of the enclosure material and its thickness required to protect other components in the same powertrain system when the high-power density motor fails unexpectedly.

Lin, Lianshan↗
DOE OSTI2021

Electron Dynamics Within a MITL Containing a Load

In this paper, we derive the vacuum electric fields within specific cylindrically symmetric magnetically insulated transmission lines (MITLs) in the limit of an infinite speed of light for an arbitrary time-dependent current. We focus our attention on two types of MITLs: the radial MITL and a spherically curved MITL. We then simulate the motion of charged particles, such as electrons, present in these MITLs due to the vacuum fields. In general, the motion of charged particles due to the vacuum fields is highly nonlinear since the fields are nonlinear functions of spatial coordinates and depend on an arbitrary time-dependent current drive. Using guiding center theory, however, one can describe the gross particle kinetics using a combination of $\textbf {E} \times \textbf {B}$ and $\nabla B$ drifts. In addition, we compare our approximate inner MITL field models and particle kinetics with those from a fully electromagnetic simulation code. We find that the agreement between the approximate model and the electromagnetic simulations is excellent.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Design and synthesis of diazirine‐containing dyes for polypropylene fibre: A study on the effect of alkyl chain

Abstract The dyeing of polypropylene fabrics utilising conventional‐disperse dyes often meets poor colour yield and fastness problems, fundamentally caused by the low affinity between dyes and polypropylene fibres. In this article, a new class of hydrophobic reactive dyes that can react with polypropylene were designed using diazirine moiety as a reactive group, azo structure as a chromophore, and an ester group as a linking bridge. The difference among these dyes was the alkyl chain length on the azo chromophore, which was used to fine‐tune the affinity between the dyes and fibre. The structures of the synthesised dyes and intermediates were characterised and confirmed using nuclear magnetic resonance, mass spectrometry, and infrared spectrometry. The absorption and thermal properties of the dyes were also studied to ensure their feasibility for dyeing application. In addition, the diazirine dyes were successfully applied to dye polypropylene fabrics using a two‐step process by dyeing in a non‐aqueous solvent and fixing it under heating. The dyes and polypropylene fibre were demonstrated to react, where the fixation values were in the range 64.5–76.4%. The systematic study of the structure–property relationship demonstrated the positive effect of the alkyl chain in promoting colour yield, however, accompanied by a slightly reduced fixation value. Due to the chemical bonding of the dye molecules to the fibre, the dyed polypropylene fabrics exhibited excellent colour fastness property, making the dyeing technology very promising for future industrial applications.

Guo, Guangluo↗
DOE OSTI2020

Conversion kinetics of container glass batch melting

Abstract Understanding the batch‐to‐glass conversion process is fundamental to optimizing the performance of glass‐melting furnaces and ensuring that furnace modeling can correctly predict the observed outcome when batch materials or furnace conditions change. To investigate the kinetics of silica dissolution, gas evolution, and primary foam formation and collapse, we performed X‐ray diffraction, thermal gravimetry, feed expansion tests, and evolved gas analysis of batch samples heated at several constant heating rates. We found that gas evolving reactions, foaming, and silica dissolution depend on the thermal history of the batch in a similar manner: the kinetic parameters of each process were linear functions of the square root of the heating rate. This kinetic similarity reflects the stronger‐than‐expected interdependence of these processes. On the basis of our results, we suggest that changes in furnace operating conditions, such as firing or boosting, influence the melting rate less than what one would expect without consideration of batch conversion kinetics.

Ueda, Nanako↗
DOE OSTI2023

Impact on aggregate/matrix bonding when a refractory contains zinc aluminate instead of spinel and magnesia‐chrome

The high hot strength of MgO–Cr 2 O 3 refractory is often ascribed to its intimate aggregate/matrix bonding. For a fundamental comparison with it, ~2 mm aggregates of MgO and Al 2 O 3 were separately embedded in ZnAl 2 O 4 and MgAl 2 O 4 matrices, sintered at 1600°C, and examined. It was found that similarity of thermal expansion coefficient (TEC) between the aggregate and the matrix is critical to achieve good bonding and this is more important than the extent of interdiffusion. The TEC mismatch of ≥ 5.7 × 10 -6 K -1 caused significant undesirable debonding in MgO aggregate/MgAl 2 O 4 matrix sample and MgO/ZnAl 2 O 4 despite >736 μm Zn 2+ diffusion depth in the latter. Direct bonding, as inferred from a thicker interfacial reaction layer and a greater shift of the aggregate/matrix interface before and after firing, was better in MgAl 2 O 4 /ZnAl 2 O 4 combination, followed by tabular Al 2 O 3 /ZnAl 2 O 4 and Al 2 O 3 /MgAl 2 O 4 . Powder X-ray diffraction indicated that the volatilization of ZnAl 2 O 4 at 1600°C in air was negligible compared to MgO–Cr 2 O 3 .

36 MATERIALS SCIENCE↗
DOE OSTI2025

Phase formation in the CaO–Al 2 O 3 –ZnO system as an analogue to CaO–Al 2 O 3 –MgO in spinel containing refractories

Recently, gahnite (ZnAl 2 O 4 ) is gaining attraction as a potential refractory ceramic because of the similarity of its structure and properties with those of magnesium aluminate (MgAl 2 O 4 ) spinel refractories. Formation of MgO and hibonite solid solution (CaMg x Al 12−x O 19−0.5x ; 0 ≤ x ≤ 0.18), CAM-I (Ca 2 Mg 2−3x Al 28+2x O 46 (0 ≤ x ≤ 0.3), and CAM-II (CaMg 2−3x Al 16+2x O 27 , 0 ≤ x ≤ 0.2) phases with platelet and interlocking microstructure in the CaO–Al 2 O 3 –MgO ternary system significantly enhances the high temperature mechanical properties of refractory castables. The CaO–Al 2 O 3 –ZnO ternary system has been studied, for the first time to our knowledge, in a selected compositional range with reference to the CaO–Al 2 O 3 –MgO system from 1650°C to 1700°C. The formation of ZnO and hibonite solid solution (CaZn x Al 12−x O 19−0.5x ; 0 < x < 0.18), CAZ-I (Ca 2 Zn 2−3x Al 28+2x O 46 ; 0 ≤ x ≤ 0.3), and CAZ-II (CaZn 2−3x Al 16+2x O 27 ; 0 ≤ x ≤ 0.2) phases with platelet and interlocking morphology have been found. The crystal structures and lattice parameters of ZnO and hibonite solid solution, CAZ-I, and CAZ-II are comparable, respectively, with MgO and hibonite solid solution, CAM-I, and CAM-II. Furthermore, CAZ-I and CAZ-II phases also form due to reaction between hibonite (CaO·6Al 2 O 3 ) and ZnAl 2 O 4 .

calcium aluminate cement↗