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141.
Ruckenstein E 《Journal of colloid and interface science》2002,246(2):393-400
The problem of coating a plate or a fiber through their withdrawal from a large reservoir was treated in the literature in various limiting cases. In the present paper, interpolation expressions are derived by scaling for Newtonian, Bingham, and viscoelastic fluids. The scaling analysis was also employed to explain the sharp increase in film thickness produced by inertia and the occurrence of a maximum thickness for an optimum velocity. It is also shown that, for a viscoelastic fluid, the film thickness tends to a finite value at very large withdrawal rates. An explanation is also provided for the existence of a maximum film thickness for an optimum surfactant concentration. 相似文献
142.
Clemens Berger 《Advances in Mathematics》2002,169(1):118-175
143.
Antons A Schroeder K Voigtländer B Cherepanov V Berger R Blügel S 《Physical review letters》2002,89(23):236101
The early stages of surfactant- (As, Sb) mediated homoepitaxial growth on Si (111) are examined by scanning tunneling microscopy and extensive ab initio calculations of Si(n) clusters (n=12). The results reveal the different microscopic behavior of the two surfactants: On As-covered Si (111), one exclusively finds two-dimensional islands with double-layer height which show the (1 x 1) terrace structure. On Sb-covered Si (111), the islands show two different reconstructions: at the rim of the islands a (1 x 1) structure appears, while in the center the (square root 3 x square root 3) terrace structure is observed. 相似文献
144.
Photoluminescence excitation spectroscopy and scanning-tunneling spectroscopy are used to study the electronic states in CdSe quantum rods that manifest a transition from a zero-dimensional to a one-dimensional quantum-confined structure. Both optical and tunneling spectra show that the level structure depends primarily on the diameter of the rod and not its length. With increasing diameter, the band gap and the excited state level spacings shift to the red. The level structure was assigned using a multiband effective-mass model, showing a similar dependence on rod dimensions. 相似文献
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146.
Paul D. Berger Thomas Magliozzi 《The Journal of the Operational Research Society》1992,43(11):1079-1086
This paper considers optimization of vertical co-operative promotion decisions in a direct mail operation. After presenting our model, we demonstrate that it is likely that a vertical co-operative direct mail promotional effort can result in a situation in which both the direct mailer and the manufacturer increase profits, compared with the situation where the direct mailer makes ‘optimal’ direct mail decisions without regard to any involvement with the manufacturer. We next show that the manufacturer can optimize his own profitability by agreeing to a specific (quantitatively determined) contribution to mail order costs. Finally, we illustrate how the manufacturer and direct mailer can co-operate (move away from their individual optimal decision variables), reaching an integrative, rather than a distributive solution, and jointly set the values of these decision variables, so that the total profit generated by the operation is higher than the sum of the individual profits of the two parties. 相似文献
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Beverly K Berger 《Annals of Physics》1984,156(1):155-193
The Gowdy T3 Cosmology is an exact solution to the vacuum Einstein equations interpreted to be a single polarization of gravitational waves propagating in an anisotropic, spatially inhomogeneous background. The classical behavior is reviewed and related to standard cosmological parameters. Canonical quantization of the dynamical degrees of freedom is reviewed. An adiabatic vacuum state is constructed. Adiabatic regularization is used to obtain non-divergent stress-energy tensor vacuum expectation values. Casimir energy terms due to T3 imposed discrete modes are evaluated. The vacuum expectation values are analyzed in early and late time limits and evaluated numerically. The regularized expectation value is used as a source for the classical background spacetime in the spirit of semi-classical gravity. An entirely vacuum expectation value source term produces essentially the time reverse of the classical evolution. Classical stress-energy added to the source restores the classical behavior at late times only. The combined system collapses from infinite to small but non-zero volume and reexpands. The classical singularity is replaced by a symmetric bounce. 相似文献