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141.
A two-wave-mixing microwave system under a delayed feedback control is proposed for chaotic communications in this study. Under the consideration of simple chaotic masking, Hilbert-Huang transform is proved to be an efficient way to detect characteristics of information signals via the spectrum of intrinsic mode functions. Based upon detrended fluctuation as well as multiscale entropy analyses on masking efficiency in the present system, we may suggest that Hilbert-Huang transform would be an alternative method to analyze complex dressed signals from nonlinear optoelectronic systems. 相似文献
142.
Bontempo D Li RC Ly T Brubaker CE Maynard HD 《Chemical communications (Cambridge, England)》2005,(37):4702-4704
Low polydispersity poly(N-isopropylacrylamide) with a biotin end-group was obtained in one step from a biotinylated initiator for atom transfer radical polymerization and interacted with streptavidin to generate the thermosensitive polymer-protein conjugate. 相似文献
143.
Brindle CA Prado MR Janda KC Halberstadt N Lewerenz M 《The Journal of chemical physics》2005,123(6):64312
New data are reported for the mass-spectrometry fragmentation patterns of helium clusters, either pure or containing a Ne or an Ar atom. The patterns for He(n)+ and Ar+He(n) show clear evidence of structure, while those of Ne+He(n) do not. To better understand the surprising result for the Ne+He(n) fragments, diffusion quantum Monte Carlo (DMC) calculations of the energies and structural properties of these ions were performed using a diatomics-in-molecule (DIM) parametrization of the potential energy. Using DIM for electronic energy evaluation allows us to sample 10(9) configurations even for a cluster as large as Ne+He14. The results of the DMC calculation are very surprising. For n > 7, the DMC random walkers rarely venture within 100 cm(-1) of the minimum potential energy. Analysis of the resulting particle density distributions shows that the zero-point energy does more than spread the wave function around the potential-energy minima, resulting in very diffuse wave functions. For some of the clusters the quantum effects nearly exclude the region of the potential minimum from the overall wave function. An important result of this effect is that the incremental bonding energy of the nth helium atom varies quite smoothly with n, for n > 5. This eliminates the expected shell structure and explains the lack of magic-number-type features in the data. 相似文献
144.
Stevenson S Lee HM Olmstead MM Kozikowski C Stevenson P Balch AL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(19):4528-4535
The trimetallic nitride template (TNT) approach has been successfully utilized to prepare the new endohedral Lu(3)N@C(80). Well-ordered crystals of Lu(3)N@C(80).5 (o-xylene) and Sc(3)N@C(80).5 (o-xylene) form upon cooling of o-xylene solutions of these endohedrals and they are isomorphous. Although the positions of the fullerene cage (which is fully ordered and located at a crystallographic center of symmetry) and the o-xylene molecules are nearly identical in these two structures, the positioning of the metal ions in the two crystals differ in significant ways. However, the expected difference in sizes of lutetium and scandium does not affect the dimensions of the C(80) cage. Nevertheless, the positions of the metal atoms do produce a slight outward dislocation of the immediately adjacent carbon atoms. 相似文献
145.
Sydney C. K. Chu Carrie K. Y. Lin Kevin Y. K. Ng 《The Journal of the Operational Research Society》1991,42(7):525-536
This paper considers the problem of planning effective servicing support of a Hong Kong-based company by providing sufficient technicians to repair/service copier machines at numerous customer sites throughout the city. As quality of service depends on its operational responsiveness, there is an urgent need to address the company's present and projected staffing.Mathematical modelling techniques based on the well-tested square-root response distance formulation of Kolesar et al. and a corresponding affine time-distance relationship are successfully applied to quantify the performance measure with respect to manpower resources. The numerical results enable model validation against collected data as well as analyses of different modes of centralized/decentralized, prioritized/non-prioritized service operations. Parametric study of performance versus resource offers further insights and directions towards the goal of optimal manpower planning.The approach is found to be very useful in an actual decision support setting, owing to its ease of adaptation, generalization and robust numerical modelling. 相似文献
146.
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148.
Luis C. Villamizar Prapas Lohateeraparp Jeffrey H. Harwell Daniel E. Resasco Bor Jier Shiau 《Transport in Porous Media》2013,96(1):63-81
Single-walled carbon nanotube-silica nanohybrid particles are a very promising material that could be used for enhanced oil recovery because of their interfacial activity. To demonstrate the basic principle, aqueous nanohybrid particle dispersions were evaluated by looking at the effect of pH, surfactant, and polymer. The results showed that pH did not have significant effect on the dispersion stability of nanohybrid particles. Although surfactant could improve the dispersion stability, it reduced the interfacial activity of the nanohybrid particles, causing them to stay in the aqueous phase. The best nanohybrid particle dispersion stability was found upon polymer addition, where the dispersions were stable for more than a week even at low polymer concentration (50?ppm). One-dimensional sand-pack studies were performed to evaluate the flow of the nanohybrid particles through porous media. The results showed that most of the nanohybrid particles (>99%) could pass through a column packed with glass beads while a measurable fraction of the particles was retained in the column packed with crushed Berea. When the columns contained a residual saturation of decane, additional nanohybrid particles were retained at the oil/water interface in both glass beads and crushed Berea sand media. The sand pack studies showed that not only can the nanohybrid particles flow through porous media but also about half of the particles injected will go the O/W interface when the porous medium contains a residual saturation of hydrocarbon, where they could be used to support a catalytic conversion of components of the oil in reservoirs. 相似文献
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150.
A remarkably versatile synthesis of cis-stilbenoid hydrocarbons containing highly functionalized phenyl groups is developed via an efficient palladium-catalyzed coupling of aryl Grignard reagents with trans-1,2-dibromoalkenes (generally obtained via bromination of the corresponding dialkylacetylenes) in tetrahydrofuran. 相似文献