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991.
In this paper, we show the results of an experimental study about the most important algorithms proposed to solve the Maximum
Flow problem. The appropriate statistical analysis not only allows us to justify comparisons between the different procedures
but also to obtain classifications of their practical efficiency. Furthermore, an empirical experiment allows us to identify
the influence of several parameters that are not included in a theoretical study. 相似文献
992.
The reaction Fe(CN)4(bpy)2? + S2O82? has been studied in aqueous micellar solutions of N‐tetradecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐14. The influence of changes in the surfactant concentration as well as in the peroxodisulfate ions concentration on kobs was investigated. Spectroscopic and conductivity measurements have given information about the distribution of both anionic reagents between the aqueous and micellar pseudophases of the SB3‐14 micellar solutions. A discussion about the adequacy of various equations based on the pseudophase model to rationalize kinetic micellar effects for anion‐anion reactions in sulfobetaine micellar solutions has been done. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 225–231, 2001 相似文献
993.
Ibon Alkorta Fernando Blanco Pere M. Deyà José Elguero Carolina Estarellas Antonio Frontera David Quiñonero 《Theoretical chemistry accounts》2010,126(1-2):1-14
This review covers two aspects concerning cooperativity in multiple weak bonds: a summary of literature results and a theoretical study of a complete series of model complexes. All the 15 combination of five weak bonds were explored: hydrogen bonds, hydric bonds, dihydrogen bonds, halogen bonds and ion–π interactions. Since in several cases there were no examples reported, a systematic exploration has been carried out on simple models at the MP2/aug-cc-pVTZ level. The results thus obtained have been analyzed using the atoms in molecules methodology. 相似文献
994.
995.
Alexandra Muoz‐Bonilla Enrique Lpez Madruga Marta Fernndez‐García 《Journal of polymer science. Part A, Polymer chemistry》2005,43(1):71-77
The atom transfer radical polymerization of cyclohexyl methacrylate (CHMA) is reported. Controlled polymerizations were performed with the CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine catalytic system with ethyl 2‐bromoisobutyrate as the initiator in bulk and different solvents (25 vol %) at 40 °C. The polymerization of CHMA in bulk resulted in a controlled polymerization, although the concentration of active species was relatively elevated. The addition of a solvent was necessary to reduce the polymerization rate, which was dependent on the dipole moment. Well‐controlled polymers were obtained in toluene, diphenyl ether, and benzonitrile solutions. Poly(cyclohexyl methacrylate) as a macroinitiator was used to synthesize the poly(cyclohexyl methacrylate)‐b‐poly(tert‐butyl methacrylate) block copolymer, which allowed a demonstration of its living character. In addition, two difunctional initiators, 1,4‐bis(bromoisobutyryloxy) benzene and 1,2‐bis(bromoisobutyryloxy) ethane, were used to initiate the atom transfer radical polymerization of CHMA. The experimental molecular weights of the obtained polymers were very close to the theoretical ones. These, along with the relative narrow molecular weight distributions, indicated that the polymerization was living and controlled. For confirmation, two different poly(tert‐butyl methacrylate)‐b‐poly(cyclohexyl methacrylate)‐b‐poly(tert‐butyl methacrylate) triblock copolymers were also synthesized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 71–77, 2005 相似文献
996.
Hua Zhang Jianwei Mu Wei-Ping Huang 《Lightwave Technology, Journal of》2008,26(5):600-607
Accurate rational approximations to the square root operators are crucial for the bidirectional beam propagation method in simulation of strongly reflective structures. An assessment and comparison of various commonly used rational approximations is performed for both transverse electric (TE) and transverse magnetic (TM) waves. The range of validity and level of accuracy for the different approximations are studied by investigating the structures with varying reflection intensities. Guidelines for accurately modeling of evanescent and propagating modes are provided. 相似文献
997.
An anatomically accurate eye model with a shell-structure lens 总被引:1,自引:0,他引:1
A human eye model based on anatomically accurate eye model previously proposed by Liou, has been transformed into a new eye model, in which laminated structure of the lens is considered. The crystalline lens is presented in the form of hundreds of shells with rotational symmetry, and with constant index within each shell. The refractive index increases from the cortical shell to the inner one, according to the equation proposed by Smith G. et al. The anterior surface of the lens is prolate, whereas the posterior surface of the lens is oblate which is consistent with the anatomical data. A ray tracing procedure has been applied to study the refractive structure of the eye. The optical characters of the model have been studied. The reason that the wings occur on the spherical aberration curve has been given. And we found that the lens with gradient refractive index and lens with shell structure can give same longitudinal spherical aberration results. 相似文献
998.
999.
1000.
Acoustic maps are the main diagnostic tools used by authorities for addressing the growing problem of urban acoustic contamination. Geostatistics models phenomena with spatial variation, but restricted to homogeneous prediction regions. The presence of barriers such as buildings introduces discontinuities in prediction areas. In this paper we investigate how to incorporate information of a geographical nature into the process of geostatistical prediction. In addition, we study the use of a Cost-Based distance to quantify the correlation between locations. 相似文献