1,160 research outputs found

    Investigation of space shuttle launch vehicle external tank nose configuration effects (model 67-OTS) in the Rockwell International 7 by 7 foot trisonic wind tunnel (IA69)

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    Wind tunnel aerodynamic investigations were conducted on an 0.015-scale representation of the space shuttle launch configuration. The primary test objectives were to investigate shock wave formation and record the aerodynamic stability and control effects generated by a new external tank nose configuration (MCR 467) at a Mach number of 1.2. Schlieren photographs were taken at angles of attack of -4 deg, 0 deg, and 4 deg, beta = 0 deg with force and pressure data recorded over the alpha range of -4 deg equal to or less than alpha equal to or less than 4 deg at beta = + or - 4 deg. The launch configuration model, consisting of the VL70-00014OA/B Orbiter, the VL78-000041B ET, and the VL77-000036A SRBs, was sting mounted on a 2.5-inch Task type internal balance entering through the ET base region. Wing, body, and base pressure lines for all orifices were routed internally through the model to the sting support system. Parametric variation consisted only of altering the ET nose configuration

    Stability and control characteristics for the inner mold line configuration of the space shuttle orbiter (OA110)

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    Experimental aerodynamic investigations were conducted on a sting mounted 0.0405-scale representation of the -140A/B inner mold line (IML) space shuttle orbiter in 7.75 x 11 foot low speed wind tunnel, during the time period from 18 March 1974 to 20 March 1974. The primary test objectives were to establish basic longitudinal and lateral-directional stability and control characteristics for the IML orbiter. Additional configurations investigated were sealed elevon hingeline gaps, sealed rudder split line and hingeline gaps, larger radius leading edge on the vertical tail, and sealed speedbrake base. Aerodynamic force and moment data for the orbiter were measured in the body-axis system by an internally mounted, six-component strain gage balance. The model was sting mounted with the center of rotation located at approximately the wing trailing edge. The nominal angle of attack range was from -4 to +30 degrees. Yaw polars were recorded over a nominal yaw angle range from -14 to +14 degrees at constant angles of attack of 0, + or - 5, 10, 15 and 20 degrees

    Charge Pumping Through a Single Donor Atom

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    Presented in this paper is a proof-of-concept for a new approach to single electron pumping based on a Single Atom Transistor (SAT). By charge pumping electrons through an isolated dopant atom in silicon, precise currents of up to 160 pA at 1 GHz are generated, even if operating at 4.2 K, with no magnetic field applied, and only when one barrier is addressed by sinusoidal voltage cycles.Comment: 14 pages, 10 figures, few changes in the text and in figure 8, New J. Phys. (2014) at pres

    A nonlinear analysis for sloshing forces and moments on a cylindrical tank

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    Sloshing forces and moments on cylindrical tank - integration of nonlinear force equation

    An approximate nonlinear analysis of the stability of sloshing modes under transla- tional and rotational excitation

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    Nonlinear analysis of sloshing mode stability under translational and rotational excitatio

    Multiple transitions of the spin configuration in quantum dots

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    Single electron tunneling is studied in a many electron quantum dot in high magnetic fields. For such a system multiple transitions of the spin configuration are theoretically predicted. With a combination of spin blockade and Kondo effect we are able to detect five regions with different spin configurations. Transitions are induced with changing electron numbers.Comment: 4 pages, 5 figure

    Interaction-Induced Spin Polarization in Quantum Dots

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    The electronic states of lateral many electron quantum dots in high magnetic fields are analyzed in terms of energy and spin. In a regime with two Landau levels in the dot, several Coulomb blockade peaks are measured. A zig-zag pattern is found as it is known from the Fock-Darwin spectrum. However, only data from Landau level 0 show the typical spin-induced bimodality, whereas features from Landau level 1 cannot be explained with the Fock-Darwin picture. Instead, by including the interaction effects within spin-density-functional theory a good agreement between experiment and theory is obtained. The absence of bimodality on Landau level 1 is found to be due to strong spin polarization.Comment: 4 pages, 5 figure

    Non-invasive detection of molecular bonds in quantum dots

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    We performed charge detection on a lateral triple quantum dot with star-like geometry. The setup allows us to interpret the results in terms of two double dots with one common dot. One double dot features weak tunnel coupling and can be understood with atom-like electronic states, the other one is strongly coupled forming molecule-like states. In nonlinear measurements we identified patterns that can be analyzed in terms of the symmetry of tunneling rates. Those patterns strongly depend on the strength of interdot tunnel coupling and are completely different for atomic- or molecule-like coupled quantum dots allowing the non-invasive detection of molecular bonds.Comment: 4 pages, 4 figure

    A Thin Cylindrical Shell Problem

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    This paper considers the problem of a thin cylindrical shell sector clamped on two curved edges and one straight edge, free on the remaining straight edge and loaded by a load similar to a hydrostatic load. The method of solution is that of superimposing the solutions of three separate problems with appropriate boundary conditions
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