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  • 34.70  (1)
  • 42.70.Df  (1)
  • Building effects  (1)
  • Chemical Engineering  (1)
  • 1
    ISSN: 1432-0630
    Keywords: 79.20R ; 34.50 ; 34.70 ; 79.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Transient adsorption or skipping motion of silicon ions scattered under specular conditions from a Cu(111) surface is reported. The phenomena is identified on the basis of the observation of discrete energy loss peaks in the scattered positive and negative ion kinetic energy distributions, together with their behaviour upon variation of the crystal azimuth, incidence angle of the beam to the surface, and scattering angular distributions. Up to five reflections in a binding potential were seen. We propose that the beam is trapped following an energy loss, by electron-hole pair or plasmon excitation, which exceeds the incident beam energy component normal to the surface. The results lend strong support to the thesis that ion beam techniques can probe the family of potential surfaces upon which adsorption and reaction, at thermal energies, proceed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 61 (1995), S. 59-62 
    ISSN: 1432-0649
    Keywords: 42.70.Df
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Low-molar-mass liquid crystals consisting of a binary nematic mixture of twoβ-naphthylester which exhibit an anisotropic glassy state at room temperature have recently proven to be a suitable material for erasable optical data-storage applications. Using the holographic-grating technique, it is shown that more than 1000 all-optical write, read and erase cycles can be realized without remarkable loss of reversibility. The recording intensities are of the order of 100 W/cm2 and optical erasure can be achieved with about twice that intensity. The times for recording and erasure of the optical gratings range on the millisecond scale and the stored gratings persist several months with a diffraction efficiency of typically 1 %. The spatial resolution has been proven down to 2 µm so far. The obtained results are compared with other reversible recording materials.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Boundary layer meteorology 97 (2000), S. 25-45 
    ISSN: 1573-1472
    Keywords: Building effects ; Roughness length ; Turbulence scale ; Urban canopy ; Urban pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A simple model originally derived for meanwind speed profiles in vegetative canopy flows ismodified for application to arrays ofthree-dimensional surface obstacles (cubes), whichcould be representative of a simple urban-typesurface. It is shown that for cube arrays that arenot too densely packed, the predicted exponentialvelocity profile provides an adequate fit to thespatially averaged velocity profile (u(z))within the obstacle canopy. Application of the model to a set of wind-tunnel dataallows for the evaluation of an empirical fittingparameter called the attenuation coefficient. This isrelated to the turbulence length scale, which can befound by manipulating the results of thegradient-diffusion model used to derive the velocityprofile. The results show a reduction of theturbulence length scale with increasing obstaclepacking density. By assuming a linear transition fromthis length scale at the top of the canopy to theclassical Prandtl length scale in the overlyinginertial sublayer, an acceptable model is obtained forthe full velocity profile within simple obstaclearrays, from the ground up to the overlyingsemi-logarithmic region.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1-8 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Results of a computer study are reported applying data reconciliation and interpretation techniques to a single-stage flash operation. Measured errors in the process variables are significantly reduced. The techniques are successfully extended to estimate flash efficiency. The flash efficiency is estimated using two methods: (1) a statistically rigorous simultaneous data reconciliation and efficiency estimation procedure, and (2), a faster, nonrigorous sequential procedure. It is found that the simultaneous procedure provides better measured variable and flash efficiency estimates.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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