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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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The effect of spark timing and negative valve overlap on Spark Assisted Compression Ignition combustion heat release rate
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Relationship between manual air valve positioning, water quality and energy usage in activated sludge processes
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Multiported Pulsed Valve Interface for a Linear Quadrupole Ion Trap Mass Spectrometer to Enable Rapid Screening of Multiple Functional-Group Selective Ion–Molecule Reactions
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Active control of magnetoresistance of organic spin valves using ferroelectricity
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Controllable 0–π Josephson junctions containing a ferromagnetic spin valve
Superconductivity and ferromagnetism are antagonistic forms of order, and rarely coexist. Many interesting new phenomena occur, however, in hybrid superconducting/ferromagnetic systems. For example, a Josephson junction containing a ferromagnetic material can exhibit an intrinsic phase shift of π in its ground state for certain thicknesses of the material. Such ‘π-junctions’ were first realized experimentally in 2001, and have been proposed as circuit elements for both high-speed classical superconducting computing and for quantum computing. Here we demonstrate experimentally that the phase state of a Josephson junction containing two ferromagnetic layers can be toggled between 0 and pi by changing the relative orientation of the two magnetizations. These controllable 0–π junctions have immediate applications in cryogenic memory, where they serve as a necessary component to an ultralow power superconducting computer. Such a fully superconducting computer is estimated to be orders of magnitude more energy-efficient than current semiconductor-based supercomputers. Here, phase-controllable junctions also open up new possibilities for superconducting circuit elements such as superconducting ‘programmable logic’, where they could function in superconducting analogues to field-programmable gate arrays.
Enhancement of magnetoresistance using CoFe/Ru/CoFe synthetic ferrimagnetic pinned layer in BiFeO{sub 3} based spin-valves
SrTiO{sub 3} (100) sub/BiFeO{sub 3}/CoFe/Ru/CoFe/Cu/CoFe/Ta structure was prepared by a combination of chemical solution deposition and sputtering method, and followed by a systematical investigation for the structural, magnetic and magnetoresistance properties at room temperature (RT) as a function of CoFe and Ru thicknesses. It was revealed that introduction of synthetic CoFe/Ru/CoFe as a pinning layer increased the giant magentoresistance (MR) ratio to 8.3% at RT. This enhancement of MR ratio might be attributed to (i) the increase of pinning field, and (ii) suppression of the influence of the surface roughness of BiFeO{sub 3} by inserting the synthetic CoFe/Ru/CoFe layer.
Local magnetoresistance in Fe/MgO/Si lateral spin valve at room temperature
Room temperature local magnetoresistance in two-terminal scheme is reported. By employing 1.6 nm-thick MgO tunnel barrier, spin injection efficiency is increased, resulting in large non-local magnetoresistance. The magnitude of the non-local magnetoresistance is estimated to be 0.0057 Ω at room temperature. As a result, a clear rectangle signal is observed in local magnetoresistance measurement even at room temperature. We also investigate the origin of local magnetoresistance by measuring the spin accumulation voltage of each contact separately.
Magnetotransport properties of spin-valve structures with Mg spacer layers
A theoretical prediction by Wang et al. [Phys. Rev. B 82, 054405 (2010)] suggests the preferential transmission of majority-spin states with Δ{sub 1} symmetry across a magnesium interlayer in Fe/Mg/MgO/Fe based magnetic tunnel junctions. Here, we report experiments to probe this question in CoFe/Mg/CoFe structures. We find that the strength of the interlayer coupling decays exponentially with increasing the spacer thickness, however, a non-monotonic variation of the magnetoresistance as a function of the Mg layer is observed. These data may help revisit the role of the insertion of a Mg interface layer in MgO-based devices.
Spin valve with non-collinear magnetization configuration imprinted by a static magnetic field
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Thermal Hydraulic Static Operation of a Chloride Molten Salt Shut Off Valve.
Abstract not provided.
Thermal gradients and anomalous Nernst effects in membrane-supported nonlocal spin valves
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Asymmetric magnetization reversal in dipolarly coupled spin valve structures with perpendicular magnetic anisotropy
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Multiterminal High-Voltage dc Systems with Series-Parallel Valve Group-Based High-Voltage dc Substations
To transfer large amount of power over long distances, multiterminal direct current (MTdc) system based on bipole high-voltage direct current (HVdc) technology is a viable option. However, such system results in large dc transmission loss. The same can be reduced by increasing the dc voltage level. This paper introduces a new MTdc system architecture comprising of series (for increasing dc voltage level) and parallel (for increasing dc current capability) connected HVdc converters. The new architecture is compared with the bipole MTdc architecture in terms of equipment needed and dc transmission loss. The control modifications needed for the MTdc system are identified and the performance of the developed control is verified through electromagnetic transient (EMT) simulations.