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291.
Controlling the phase delay of light transmitted through double-layer metallic subwavelength slit arrays 总被引:1,自引:0,他引:1
Marcet Z Paster JW Carr DW Bower JE Cirelli RA Klemens F Mansfield WM Miner JF Pai CS Chan HB 《Optics letters》2008,33(13):1410-1412
We demonstrate that the phase of light transmitted through double-layer subwavelength metallic slit arrays can be controlled through lateral shift of the two layers. Our samples consist of two aluminum layers, each of which contains an array of subwavelength slits. The two layers are placed in sufficient proximity to allow coupling of the evanescent fields at resonance. By changing the lateral shift between the layers from zero to half the period, the phase of the transmitted electromagnetic field is increased by pi, while the transmitted intensity remains high. Such a controllable phase delay could open new capabilities for nanophotonic devices that cannot be achieved with single-layer structures. 相似文献
292.
Hui-Ming Pai 《Queueing Systems》2010,64(4):325-358
This paper considers multiclass queueing network systems with fixed routing. With the service control as one player and the
arrival and service rates as the other, the problem of network regulation can be formulated as a differential game. Representations
of the value function are developed by studying the geometric properties of the associated Hamiltonians and are expressed
in terms of related simpler halfspace problems. Also, a method of constructing the optimal feedback controls through the representation
and the projected Isaacs equations is provided. The controls so constructed give both a guaranteed level of performance and
robust stability over a range of rate perturbations. 相似文献
293.
294.
A second-order closure turbulence model is used to simulate the plume behaviour of a passive contaminant dispersed in a convective boundary layer. A time-splitting finite element scheme is used to solve the set of partial differential equations. It is shown that the second-order closure model compares favourably with recent findings from laboratories, wind-tunnel experiments and large-eddy simulations. We also compare the second-order closure model with the commonly used K-diffusion model for the same meteorological conditions. Case studies also show the effects of model parameters and turbulence variables on the plume behaviour. 相似文献
295.
Tylophorine has been degraded to a compound, identified as 2:3:6:7-tetramethoxy-9-methylphenanthrene. In conjunction with other degradation results and biogenetic considerations, tylophorine is now formulated as 2:3:6:7-tetramethoxyphenanthro(9:10:6′:7′)indolizidine.
A synthesis of the basic ring system, phenanthro-(9:10:6′:7′)indolizidine, present in tylophorine has been achieved. 相似文献
296.
297.
Triterpenes of Calophyllum inophyllum Linn 总被引:1,自引:0,他引:1
298.
S. K. Mundra S. A. Pai M. S. Subramanian 《Journal of Radioanalytical and Nuclear Chemistry》1987,116(1):203-211
Synergistic extraction of uranyl ion with acylpyrazolones such as 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 (HPMTFP, pKa=2.7), 1-phenyl-3-methyl-4-acetylpyrazolone (HPMAP, pKa=3.8) or 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP, pKa=4.2) in combination with dicyclohexano-18-crown-6 (DC-18-C6) has been studied at various fixed temperatures. The results indicate that the equilibrium constants of the organic phase addition reaction, log Ks, at 30°C are almost constant, viz., 2.72, 2.69 and 2.84, respectively, for the above three systems. The similarity and low log Ks values with DC-18-C6 as compared with TBP systems with these pyrazolones appears to arise due to the limitation to the approach of the large crown ether molecule in bonding with the uranyl chelate. This is in contrast to the fact that the relative basicities of the two donors (equilibrium constant for nitric acid uptake) are comparable. Thermodynamic data for chelate extraction with HPMTFP evaluated by the temperature coefficient method indicates that a hydrated chelate is extracted into the organic phase. Also, the organic phase addition reaction with DC-18-C6 is stabilized by exothermic enthalpy change, the entropy change counteracting in all the three cases. 相似文献
299.
300.
P. R. Nambiar V. R. Pai Verneker S. R. Jain 《Journal of Thermal Analysis and Calorimetry》1975,7(3):587-592
The thermal decomposition of methylammonium perchlorate (MAP) has been studied under isothermal and non-isothermal conditions. Differential thermal analysis of MAP showed, in addition to the exotherm due to decomposition, another exotherm at 408° which was observed for the first time. Chemical analysis and the infrared spectrum of the residue left behind after the decomposition proved it to contain NH4ClO4. The results have been explained on the basis of a methyl group transfer in addition to proton transfer in the decomposition process. 相似文献