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171.
172.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献
173.
Sung‐Fu Hsu Tzong‐Ming Wu Chien‐Shiun Liao 《Journal of Polymer Science.Polymer Physics》2006,44(23):3337-3347
Poly(3‐hydroxybutyrate) (PHB)/layered double hydroxides (LDHs) nanocomposites were prepared by mixing PHB and poly(ethylene glycol) phosphonates (PEOPAs)‐modified LDH (PMLDH) in chloroform solution. Both X‐ray diffraction data and TEM micrographs of PHB/PMLDH nanocomposites indicate that the PMLDHs are randomly dispersed and exfoliated into the PHB matrix. In this study, the effect of PMLDH on the isothermal crystallization behavior of PHB was investigated using a differential scanning calorimeter (DSC) and polarized optical microscopy. Isothermal crystallization results of PHB/PMLDH nanocomposites show that the addition of 2 wt % PMLDH into PHB induced more heterogeneous nucleation in the crystallization significantly increasing the crystallization rate and reducing their activation energy. By adding more PMLDH into the PHB probably causes more steric hindrance of the diffusion of PHB, reducing the transportation ability of polymer chains during crystallization, thus increasing the activation energy. The correlation among crystallization kinetics, melting behavior and crystalline structure of PHB/PMLDH nanocomposites can also be discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3337–3347, 2006 相似文献
174.
L. A. Gil‐Alana 《商业与工业应用随机模型》2006,22(4):385-395
This article examines the length of the cycles in the gross domestic product (GDP) real per capita series of 15 countries by means of new statistical techniques based on unit root cycles. We propose tests for unit root cycles at each of the frequencies of the process. Using this approach, we are able to approximate the number of periods per cycle. The results show that the cycles have a periodicity of approximately six years when the disturbances are white noise. However, if we permit autocorrelation, they may also occur at smaller intervals of time. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
175.
176.
Jian‐guo Tang 《Mathematical Methods in the Applied Sciences》2006,29(11):1327-1338
An implicit iterative method is applied to solving linear ill‐posed problems with perturbed operators. It is proved that the optimal convergence rate can be obtained after choosing suitable number of iterations. A generalized Morozov's discrepancy principle is proposed for the problems, and then the optimal convergence rate can also be obtained by an a posteriori strategy. The convergence results show that the algorithm is a robust regularization method. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
177.
178.
This paper is devoted to the proof of almost global existence results for Klein‐Gordon equations on Zoll manifolds (e.g., spheres of arbitrary dimension) with Hamiltonian nonlinearities, when the Cauchy data are smooth and small. The proof relies on Birkhoff normal form methods and on the specific distribution of eigenvalues of the Laplacian perturbed by a potential on Zoll manifolds. © 2007 Wiley Periodicals, Inc. 相似文献
179.
180.
Jiaqiang Wang Hua Fang Ying Li Junjie Li Zhiying Yan 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):75-79
Cobalt-doped mesoporous titania with a crystalline framework synthesized by surfactant templating method presented highly selective (99%) and reasonable conversion rate (49%) of catalytic oxidation of para-chlorotoluene to para-chlorobenzaldehyde in acetic acid using aqueous hydrogen peroxide as oxidant for the first time. Recycling of the catalyst indicates that the catalyst can be used a number of times without losing its activity to a greater extent. By contrast, cobalt-doped mesoporous titania without a crystalline structure and cobalt doped the commercial titania, Degussa P25 prepared by impregnation method with the similar concentration of cobalt were found inactive. The effects of catalyst concentration, reaction time, reaction temperature, and solvents on the performance of the catalyst were also investigated. 相似文献