24,528 research outputs found

    Validation of a new flying quality criterion for the landing task

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    A strong correlation has been found to exist between flight path angle peak overshoot and pilot ratings for the landing task. The use of flightpath overshoot as a flying quality metric for landing is validated by correlation with four different in-flight simulation programs and a ground simulation study. Configurations tested were primarily medium-weight generic transports. As a result of good correlation with this extensive data base, criterion boundaries are proposed for landing based on the flight path peak overshoot metric

    Equivalence between two-mode spin squeezed states and pure entangled states with equal spin

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    We prove that a pure entangled state of two subsystems with equal spin is equivalent to a two-mode spin-squeezed state under local operations except for a set of bipartite states with measure zero, and we provide a counterexample to the generalization of this result to two subsystems of unequal spin.Comment: 6 pages, no figure

    Berry Curvature on the Fermi Surface: Anomalous Hall Effect as a Topological Fermi-Liquid Property

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    The intrinsic anomalous Hall effect in metallic ferromagnets is shown to be controlled by Berry phases accumulated by adiabatic motion of quasiparticles on the Fermi surface, and is purely a Fermi-liquid property, not a ``bulk'' Fermi sea property like Landau diamagnetism, as has been previously supposed. Berry phases are a new topological ingredient that must be added to Landau Fermi-liquid theory in the presence of broken inversion or time-reversal symmetry.Comment: 4 pages, 0 figures; to appear in Physical Review Letters; cleaner form of main formula+note added confirming continued validity of result in interacting Fermi liquids: + improved summary paragraph stating result; final published version (minor changes

    A polyphonic acoustic vortex and its complementary chords

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    Using an annular phased array of eight loudspeakers, we generate sound beams that simultaneously contain phase singularities at a number of different frequencies. These frequencies correspond to different musical notes and the singularities can be set to overlap along the beam axis, creating a polyphonic acoustic vortex. Perturbing the drive amplitudes of the speakers means that the singularities no longer overlap, each note being nulled at a slightly different lateral position, where the volume of the other notes is now nonzero. The remaining notes form a tri-note chord. We contrast this acoustic phenomenon to the optical case where the perturbation of a white light vortex leads to a spectral spatial distribution

    STUDIES ON ABLATION OF OBJECTS TRAVERSING AN ATMOSPHERE

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    Ablation-type thermal protection of objects traversing an atmosphere - earth and mar

    Musculoskeletal adaptations to physical interventions in spinal cord injury

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