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  • 1
    Electronic Resource
    Electronic Resource
    X-ray characteristics of a niobium superconducting tunnel junction with a highly transmissive tunnel barrier (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5098-5104 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of an investigation into the x-ray properties of a superconducting tunnel junction (STJ) are presented. The photoabsorption of an x-ray photon by one of the thin superconducting films of the junction results in the production of quasiparticles, which may subsequently tunnel through the thin oxide barrier into the second superconducting film. The transfer of charge across the barrier is detected, and gives a measure of both the x-ray photon energy and the effective energy gap ε of the superconducting film in which the photoabsorption occurred. A charge output of 55% of the theoretical maximum has been obtained for a niobium-based STJ. Such a charge output indicates a mean energy ε of (approximately-equal-to)4.7 meV is required to create a single charge carrier in the junction such that ε/Δ(approximately-equal-to)3, where 2Δ is the junction energy gap. This is the lowest value of ε/Δ obtained to date for x-ray photoabsorption in STJs. The energy resolution of the device is, however, still poor, with a full width half maximum of (approximately-equal-to)200 eV for 6 keV x rays, compared with the theoretical Fano limited resolution of (approximately-equal-to)4 eV. The principle mechanisms which are believed to degrade the resolution are discussed. These are principally quasiparticle recombination, phonon leakage out of the junction, quasiparticle diffusion into and out of the tunneling region, in addition to possible local variations in the energy gap. A Monte Carlo simulation of the nonequilibrium system has been performed. The results assist in the identification of the major charge loss mechanisms, and indicate various means by which Fano limited resolution may be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353782
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  • 2
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy and atomic force microscopy analysis of Nb-Al-AlOx-Nb superconducting tunnel junction detectors (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4099-4106 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance of photon detectors based on superconducting tunnel junctions are related to their current - voltage (I-V) curve characteristics and, ultimately, to the quality of the thin tunnel barriers (of order 1 nm) which separate the two superconducting thin films. Both the optimization of the spectroscopic performance of these detectors and the development of a reproducible and high yield fabrication route, require a better understanding of barrier quality and growth techniques. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) provide valuable tools for the investigation of the barrier region and for the control of the quality of the different thin films and related interfaces. In this paper, the results of a TEM and AFM evaluation of Nb-Al-AlOx-Nb tunnel junctions are reported, together with their interpretation on the basis of the I-V curve performance at low temperature (T≥0.3 K). Thickness disuniformities of the Al plus AlOx overlayer and evidence of barrier defects have been found, which may place constraints on the spectroscopic performance of such devices. Through the use of TEM it has also been possible to confirm the epitaxial nature of the Nb base electrode. The junction counter electrode however appears to be polycrystalline, with a columnar morphology and an average grain width of 40 nm. The overall structure of the various layers may well place constraints on the tunneling characteristics of the device. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359492
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  • 3
    Electronic Resource
    Electronic Resource
    The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows (1993)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 25 (1993), S. 539-575 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.25.010193.002543
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  • 4
    Electronic Resource
    Electronic Resource
    The Measurement of Turbulence with the Laser-Doppler Anemometer (1979)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 11 (1979), S. 443-503 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.11.010179.002303
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  • 5
    Electronic Resource
    Electronic Resource
    The dependence of the dissipation on rotation (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2304-2305 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A form of the evolution equation for the dissipation showing the effects of rotation is derived directly from the Navier–Stokes equations. Rotation affects the dissipation if the flow is inhomogeneous or compressible. This is due to the fact that pressure scales with inverse Rossby number and certain pressure correlations usually neglected have to be retained when Re Ro≈1. The term reflecting the effects of rotation on the dissipation is a volume integral of the two-point velocity correlation similar in structure to the "rapid-pressure'' correlation appearing in the second-moment equations. Some of its properties are indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858536
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  • 6
    Electronic Resource
    Electronic Resource
    Some comments on turbulence (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 203-211 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A few remarks are made about the average dissipation of energy in unsteady turbulent flows, and the way in which it is modeled. Some suggestions are made that place the customary models on a more rational basis, and which lead to an improved model. Sample calculations with the improved model are presented. From time to time, philosophical comments are made about turbulence as a field, theoreticians, and other subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858347
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  • 7
    Electronic Resource
    Electronic Resource
    Second-order modeling of near-wall turbulence (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 971-975 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new model form of the wall-proximity effect on the pressure-strain correlation term is carefully derived based on realizability. All other models used in this paper also satisfy realizability. As a test flow for a complete set of second-order realizable models, the turbulent boundary layer with zero-pressure gradient was calculated. Numerical solutions of the mean velocity, component energies, shear stress, and dissipation of the turbulence energy are obtained, which are in excellent agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865692
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  • 8
    Electronic Resource
    Electronic Resource
    Evolution of a non-self-preserving thermal mixing layer (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 3976-3981 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In an attempt to explain apparently anomalous measurements, a first integral of the equation relating mean temperature and heat flux is obtained using a Gram–Charlier representation. This permits relating moments of the heat flux distribution to derivatives of coefficients in the mean temperature representation. The same sort of analysis is applied to the temperature variance equation, giving other relations among coefficients. It is concluded that the measurements are consistent with a very small and rapidly decaying fourth-order component which has a surprisingly large effect on the maximum value of the heat flux. It is found that the evolution of the layer certainly cannot be described by an eddy viscosity. Several relations (e.g., connecting the integral of the heat flux with the growth of the length scale, and another giving an estimate for the temperature variance) are thought to be new, are not limited by assumptions of self-preservation, and should prove useful in analyzing other data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865738
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  • 9
    Electronic Resource
    Electronic Resource
    Drag Reduction by Additives (1969)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 1 (1969), S. 367-384 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.01.010169.002055
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  • 10
    Electronic Resource
    Electronic Resource
    No blood or blood products (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 50 (1995), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1995.tb15107.x
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