26,545 research outputs found

    Oceanic wave measurement system

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    An oceanic wave measured system is disclosed wherein wave height is sensed by a barometer mounted on a buoy. The distance between the trough and crest of a wave is monitored by sequentially detecting positive and negative peaks of the output of the barometer and by combining (adding) each set of two successive half cycle peaks. The timing of this measurement is achieved by detecting the period of a half cycle of wave motion

    Low-dimensional models for turbulent plane Couette flow in a minimal flow unit

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    We model turbulent plane Couette flow in the minimal flow unit (MFU) – a domain whose spanwise and streamwise extent is just sufficient to maintain turbulence – by expanding the velocity field as a sum of optimal modes calculated via proper orthogonal decomposition from numerical data. Ordinary differential equations are obtained by Galerkin projection of the Navier–Stokes equations onto these modes. We first consider a 6-mode (11-dimensional) model and study the effects of including losses to neglected modes. Ignoring these, the model reproduces turbulent statistics acceptably, but fails to reproduce dynamics; including them, we find a stable periodic orbit that captures the regeneration cycle dynamics and agrees well with direct numerical simulations. However, restriction to as few as six modes artificially constrains the relative magnitudes of streamwise vortices and streaks and so cannot reproduce stability of the laminar state or properly account for bifurcations to turbulence as Reynolds number increases. To address this issue, we develop a second class of models based on ‘uncoupled’ eigenfunctions that allow independence among streamwise and cross-stream velocity components. A 9-mode (31-dimensional) model produces bifurcation diagrams for steady and periodic states in qualitative agreement with numerical Navier–Stokes solutions, while preserving the regeneration cycle dynamics. Together, the models provide empirical evidence that the ‘backbone’ for MFU turbulence is a periodic orbit, and support the roll–streak–breakdown–roll reformation picture of shear-driven turbulence

    Synchronizer for random binary data

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    Simplified binary-data transition detector, for synchronization of relatively noise-free signals, can be used with radio or cable data-control links. It permits reception of binary data in absence of clock signal or self-clocking coder

    Action of lithium in radiation hardened silicon solar cells Quarterly report, 23 Apr. - 15 Jul. 1968

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    Recovery properties of lithium containing p-n silicon solar cells after radiation damag

    Socialism: Aim, methods and tactics as applied to twentieth century conditions

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    https://stars.library.ucf.edu/prism/1224/thumbnail.jp

    Study to determine and improve design for lithium-doped solar cells Quarterly report, 1 Apr. - 30 Jun. 1970

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    Lithium action effects on spontaneous annealing of radiation damage in bulk silicon and silicon solar cell

    Alternative derivation of the Feigel effect and call for its experimental verification

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    A recent theory by Feigel [Phys. Rev. Lett. {\bf 92}, 020404 (2004)] predicts the finite transfer of momentum from the quantum vacuum to a fluid placed in strong perpendicular electric and magnetic fields. The momentum transfer arises because of the optically anisotropic magnetoelectric response induced in the fluid by the fields. After summarising Feigel's original assumptions and derivation (corrected of trivial mistakes), we rederive the same result by a simpler route, validating Feigel's semi-classical approach. We then derive the stress exerted by the vacuum on the fluid which, if the Feigel hypothesis is correct, should induce a Poiseuille flow in a tube with maximum speed ≈100μ\approx 100\mum/s (2000 times larger than Feigel's original prediction). An experiment is suggested to test this prediction for an organometallic fluid in a tube passing through the bore of a high strength magnet. The predicted flow can be measured directly by tracking microscopy or indirectly by measuring the flow rate (≈1\approx 1ml/min) corresponding to the Poiseuille flow. A second experiment is also proposed whereby a `vacuum radiometer' is used to test a recent prediction that the net force on a magnetoelectric slab in the vacuum should be zero.Comment: 20 pages, 1 figures. revised and improved versio

    Radiation damage in lithium-containing solar cells Final report, 21 Jun. 1966 - 20 Mar. 1968

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    Interaction of lithium with defects induced in silicon solar cells by one MeV electron bombardmen
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