51,630 research outputs found
Method of welding joint in closed vessel improves quality of seam
To facilitate welding of closed vessels, a metal backup strip is used at the junction inside the vessel. After welding from the outside, this strip is dissolved by a chemically reactive solvent poured through a filler hole into the vessel
Air Flow Investigation for Location of Angle of Attack Head on a JN4h Airplane
The technical staff of the NACA at Langley Field, has made a series of free flight tests with a JN4h airplane in order to find the best place for an instrument for measuring the angle of attack. A "neutral zone" was found where the air remains either at rest relative to the undisturbed air beyond the influence of the airplane, or is set in motion parallel to the motion of the airplane. This zone is about midway between the two wings and slightly in front of, or at the vertical plane through the leading edges of the wings but the exact position as well as the outlines of the zone varies considerably as the conditions of flight change
Two-state system driven by imperfect pi pulses: an estimate of the error accumulation in bang-bang control methods
The evolution of a two-state system driven by a sequence of imperfect pi
pulses (with random phase or amplitude errors) is calculated. The resulting
decreased fidelity is used to derive a plausible limit on the performance of
"bang-bang" control methods for the suppression of decoherence.Comment: 9 pages, 3 figures; submitted to Journal of Modern Optic
On The Origin of Super-Hot Electrons from Intense Laser Interactions with Solid Targets having Moderate Scale Length Preformed Plasmas
We use PIC modeling to identify the acceleration mechanism responsible for
the observed generation of super-hot electrons in ultra-intense laser-plasma
interactions with solid targets with pre-formed plasma. We identify several
features of direct laser acceleration (DLA) that drive the generation of
super-hot electrons. We find that, in this regime, electrons that become
super-hot are primarily injected by a looping mechanism that we call
loop-injected direct acceleration (LIDA)
Robust Logic Gates and Realistic Quantum Computation
The composite rotation approach has been used to develop a range of robust
quantum logic gates, including single qubit gates and two qubit gates, which
are resistant to systematic errors in their implementation. Single qubit gates
based on the BB1 family of composite rotations have been experimentally
demonstrated in a variety of systems, but little study has been made of their
application in extended computations, and there has been no experimental study
of the corresponding robust two qubit gates to date. Here we describe an
application of robust gates to Nuclear Magnetic Resonance (NMR) studies of
approximate quantum counting. We find that the BB1 family of robust gates is
indeed useful, but that the related NB1, PB1, B4 and P4 families of tailored
logic gates are less useful than initially expected.Comment: 6 pages RevTex4 including 5 figures (3 low quality to save space).
Revised at request of referee and incorporting minor corrections and updates.
Now in press at Phys Rev
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