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  • 1
    Electronic Resource
    Electronic Resource
    Velocity and Reynolds stresses in a precessing jet flow (1997)
    Springer
    Experiments in fluids 22 (1997), S. 489-495 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  A novel fluid mixing device, described elsewhere, has been shown to have a dramatic effect on the combustion characteristics of a fuel jet. The main features of the flow are the deflection of the jet between 30° and 60° from the nozzle axis and its precession about that axis. Many of the factors governing the nozzle instabilities which drive the mixing in the external field are imprecisely defined. It is the aim of the present paper to examine, in isolation from the nozzle instabilities, the influence of precession on a deflected jet as it proceeds downstream from the nozzle exit. The fluid dynamically driven phenomena within the nozzle which cause the precession are in the present investigation replaced by a mechanical rotation of a nozzle from which is emerging a jet which is orientated at an angle from the nozzle axis. By this means the effect of precession on the deflected jet can be investigated independently of the phenomena which cause the precession. The experimental data reported here has been obtained from measurements made using a miniature, rapid response four-hole “Cobra” pitot probe in the field of the precessing jet. Phase-averaged three dimensional velocity components identify the large scale motions and overall flow patterns. The measured Reynolds stresses complement the velocity data and are found to be compatible with the higher entrainment rates of the jet found in earlier investigations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050076
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  • 2
    Electronic Resource
    Electronic Resource
    Velocity measurements in a precessing jet flow using a three dimensional LDA system (1997)
    Springer
    Experiments in fluids 23 (1997), S. 89-98 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The turbulent, three dimensional and time dependent flow field of a precessing jet is investigated. In the present case the jet precession is generated by mechanically rotating a round jet inclined relative to the axis of rotation. A conditional flow visualisation technique is used to complement three dimensional laser Doppler velocity data, time-averaged and phase-averaged at the frequency of precession. The conditional phase-averaging technique enables phase-averaged velocity contours and vectors to be obtained which reveal flow patterns and structures within the flow field. Time-averaging of the velocity data shows that these structures are significant in that they generate a reverse flow (recirculation) region between the jet and its spinning axis. They are found also to cause a rapid decay of the mean velocity. The characteristics of the precessing jet found here are compared with previous investigations of the same flow and with investigations of other turbulent jets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050089
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  • 3
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary X-ray crystallographic analysis of recombinant transaldolase B from Eschericha coli (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 192-193 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Recombinant transaldolase from Escherichia coli, an enzyme of the pentose phosphate pathway has been crystallized by the vapor-diffusion method using polyethylene glycol 6000 as precipitant. The crystals are orthorhombic, space group P212121 with cell dimensions a = 68.9, b = 91.3 and c = 130.5 Å and diffract to 2 Å resolution on a conventional X-ray source. The asymmetric unit very likely contains two subunits, corresponding to a packing density of 2.9 Å3 Da−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444995010365
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  • 4
    Electronic Resource
    Electronic Resource
    A method for processing diffraction data from twinned protein crystals and its application in the structure determination of an FAD/NADH-binding fragment of nitrate reductase (1995)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 13-20 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A general method to deconvolute oscillation data sets from twinned protein crystals to a corresponding single-crystal data set has been developed and applied to diffraction data measured from crystals of a fragment containing the FAD- and NADH-binding domains of nitrate reductase. The procedure allows straightforward processing of diffraction data from twinned crystals. Typically, Rmerge values of reduced data sets from the nitrate reductase crystals after deconvolution are about 0.06 compared to 0.13 and higher before deconvolution. Based on these deconvoluted data sets, the structure of the FAD- and NADH-binding domains of nitrate reductase could be solved successfully. The result indicates that crystal twinning does not necessarily prevent crystallographic structure determination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444994008693
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of roughness and interdiffusion in zone plate structures on the diffraction efficiency described by coupled wave theory (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 599-601 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diffractive transmission x-ray optics, e.g., zone plates and gratings, are well suited for x-ray microscopy and spectroscopy. X-ray optics for use at short wavelengths require high zone aspect ratios which can be obtained by alternately depositing two materials with different x-ray scattering properties on a microwire. The roughness and the diffusion inherent to this process influence the diffraction efficiency of these optics. Using coupled wave theory, it is shown that roughness and interdiffusion increase the structure height required for optimal diffraction efficiency compared to ideally smooth structure profiles. In addition, the maximum obtainable diffraction efficiency decreases with increasing root-mean-square roughness and interdiffusion. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121868
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  • 6
    Electronic Resource
    Electronic Resource
    Radiation-enhanced network formation in copolymer galvanoforms for diffractive nickel x-ray optics with high aspect ratios (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1805-1807 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-resolution x-ray microscopy makes use of nanostructured diffractive optics such as Fresnel zone plates made of nickel. These micro zone plates are manufactured using microscopic galvanoforms and electrodeposition techniques. Copolymer galvanoforms for nickel micro zone plates were irradiated with high doses of x-ray radiation to increase the degree of cross-linking of the copolymer network; in this way, exact pattern replication in the galvanoform was obtained for zone aspect ratios of up to 8:1. Using these galvanoforms, nickel micro zone plates were produced for the soft x-ray wavelength λ=2.4 nm, with smallest zone widths of 30 nm and 40 nm, achieving first-order diffraction efficiencies of up to 13% and 20%, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121190
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  • 7
    Electronic Resource
    Electronic Resource
    Calculation of the magnetocrystalline anisotropy energy using a torque method : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3869-3871 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We calculate the torque on a magnetic moment with arbitrary orientation in a solid and use it to calculate the magnetocrystalline anisotropy energy (MAE) of bulk materials by integrating the torque along an angular path connecting the easy and hard magnetization directions. We apply this approach to the calculation of the MAE of elemental ferromagnets Ni and Fe using a tight-binding model with an added spin-orbit-coupling (SOC) term λSOL⋅S. The MAE for both Fe and Ni is computed for a wide range of values of the SOC strength. Our results for the MAE calculated with the torque method agree with the MAE determined from energy differences. The convergence rate as a function of k-vector needed for integrating over the Brillouin zone for the torque method is comparable to the convergence rate of conventional energy difference schemes. We compare the calculated torque as function of angle to the lowest order term in the expansion in anisotropy constants. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364737
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  • 8
    Electronic Resource
    Electronic Resource
    Zone plates with high efficiency in high orders of diffraction described by dynamical theory (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2242-2244 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The coupled wave theory is applied to calculate the diffraction efficiency of zone plates used in high orders of diffraction. In contradiction to the existing understanding about 30%–50% of the incident intensity can be diffracted by a single high order if the line-to-space ratio of the zone structures is in the range of 0.1–0.5 and the aspect ratios are larger than 30:1. Highly efficient diffractive transmission x-ray optics with high numerical apertures and resolving power can be developed without manufacturing extremely small zones which are necessary for zone plates used in the first order. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120069
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  • 9
    Electronic Resource
    Electronic Resource
    A Fluorinated D-Homoestrone Derivative (1996)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 2258-2259 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270196003897
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  • 10
    Electronic Resource
    Electronic Resource
    NICMOS/HST Post-Perihelion Images of Comet Hale-Bopp in Outburst (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 243-249 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Near-infrared images of comet Hale-Bopp (C/1995 O1) were obtained from NICMOS/HST on UT August 27–28, 1997, when the comet emerged from the 50 degree solar elongation limit at 2.99 AU from Earth. Diffraction-limited images were obtained with camera 2 filters centered at 1.87, 1.90, 2.04 and 2.22 μm with ∼0.2″ resolution (0.076″/pixel; 165 km/pixel). Over the 1.7-hour baseline of observation, a recent (〈7 hours) outburst is seen in the form of an expanding spiral arm with a projected expansion velocity of ∼80 m/s. Other asymmetric features include a jet emanating from the nucleus and several static linear features. Comparisons of the flux distribution in the 2.04 and 2.22 μm filters indicate that the region near the nucleus exhibits a slight, ∼3%, water ice absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006209302147
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