13,074 research outputs found

    Evaluation of a Wake Vortex Upset Model Based on Simultaneous Measurements of Wake Velocities and Probe-Aircraft Accelerations

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    Simultaneous measurements were made of the upset responses experienced and the wake velocities encountered by an instrumented Learjet probe aircraft behind a Boeing 747 vortex-generating aircraft. The vortex-induced angular accelerations experienced could be predicted within 30% by a mathematical upset response model when the characteristics of the wake were well represented by the vortex model. The vortex model used in the present study adequately represented the wake flow field when the vortices dissipated symmetrically and only one vortex pair existed in the wake

    Preliminary Checklist of the Fishes of the Illinois River, Arkansas

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    A survey of the fishes of the mainstream of the Illinois River in northwestern Arkansas produced 51 species representing 11 families. Four of these species, Ictiobus bubalus, smallmouth buffalo; Moxostoma carinatum, river redhorse; Lepomis gulosus, warmouth; and Percina phoxocephala, slenderhead darter, have not been recorded previously from the Arkansas part of the Illinois. Eleven additional species have been reported previously that were not collected during this survey, for a total of 62 species known in the Illinois River

    Quantum equilibration in finite time

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    It has recently been shown that small quantum subsystems generically equilibrate, in the sense that they spend most of the time close to a fixed equilibrium state. This relies on just two assumptions: that the state is spread over many different energies, and that the Hamiltonian has non-degenerate energy gaps. Given the same assumptions, it has also been shown that closed systems equilibrate with respect to realistic measurements. We extend these results in two important ways. First, we prove equilibration over a finite (rather than infinite) time-interval, allowing us to bound the equilibration time. Second, we weaken the non degenerate energy gaps condition, showing that equilibration occurs provided that no energy gap is hugely degenerate.Comment: 7 page

    Colonial History & Anglo-American tension: Allegheny Uprising & Drums along the Mohawk

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