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51.
We investigate an operator renormalization group method to extract and describe the relevant degrees of freedom in the evolution of partial differential equations. The proposed renormalization group approach is formulated as an analytical method providing the fundamental concepts of a numerical algorithm applicable to various dynamical systems. We examine dynamical scaling characteristics in the short-time and the long-time evolution regime providing only a reduced number of degrees of freedom to the evolution process. 相似文献
52.
Jerónimo Rodríguez 《Comptes Rendus Mathematique》2004,339(6):445-450
In the present Note we introduce an extension of the conservative space–time mesh refinement method presented by Fouquet et al. We also propose a post-treatment of the solution that reduces the spurious phenomena due to the non-conformity between the time meshes. A reinterpretation of the equations in terms of new unknowns leads to a new scheme with second order consistent coupling equations. Numerical experiments in 2D and a plane wave analysis for the 1D model show that the method is second order accurate for an arbitrary refinement. To cite this article: J. Rodríguez, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
53.
Antonio Uris Jose Maria Bravo Jaime Llinares Hermelando Estelles 《Applied Acoustics》2004,65(4):421-430
In this paper the influence on sound reduction index of the length and the depth of sound leaks at the perimeter of lightweight partitions was examined. It was shown that the most important decrease on sound reduction index is caused by the first slit between lightweight partition and one of the structural members. When the length of the slit is increased, the decrease on sound reduction index is less significative. Calculated results show the same effects as measured ones. 相似文献
54.
Palladium-containing zeolites catalyze the cycloisomerization of diethyl diallylmalonate to dimethylcyclopentenes. When the reaction is carried out in toluene, the performance of the palladium catalyst depends on the pore size of the zeolites. At 60 °C, palladium adsorbed on large pore size Beta zeolite (pore size ∼7.4 Å) is more active than medium pore size ZSM-5 (pore size ∼5.4 Å). This lower activity of ZSM-5 compared to Beta is attributable to the restricted diffusion of reagent and products through the ZSM-5 channels as compared to Beta zeolite. However, due to the gas-like diffusion characteristic of the supercritical state, the activity of ZSM-5 increases and becomes identical to that of Beta zeolite using supercritical CO2 as medium. 相似文献
55.
Ana Luísa Daniel‐da‐Silva João Carlos Moura Bordado José Miguel Martín‐Martínez 《Journal of Polymer Science.Polymer Physics》2007,45(22):3034-3045
The degree of phase separation in several moisture‐cured poly(urethane urea)s (PUUs) was studied by FTIR spectroscopy, wide angle X‐ray diffraction (WAXD), and temperature‐modulated differential scanning calorimetry (TMDSC). This latter technique was shown to be particularly useful in analysing the degree of phase separation in PUU polymers. Both phase mixing and phase segregation coexisted in the PUUs and the degree of phase separation increased as the urea hard segment (HS) content in the PUU increased. The maximum solubility of urea HSs into the polyol soft segments (SSs) was achieved for 50 wt % urea HS content in diol‐based PUUs, whereas for triol‐based PUUs the highest solubility between HS and SS was reached for lower urea HS amount. Finally, the higher the urea HS content the higher the extent of phase separation in the PUU. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3034–3045, 2007 相似文献
56.
Antonio Longi 《Fresenius' Journal of Analytical Chemistry》1884,23(1):149-151
Ohne Zusammenfassung 相似文献
57.
Oleg Palumbíny 《Czechoslovak Mathematical Journal》2003,53(2):467-477
The paper deals with oscillation criteria of fourth order linear differential equations with quasi-derivatives. 相似文献
58.
Monika Goikoetxea María J. Barandiaran José M. Asua 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):5838-5846
The mechanisms involved in the formation of n‐butanol during the synthesis of butyl acrylate containing latices were investigated. The experimental results showed that neither the hydrolysis of butyl acrylate nor of the ester bond in the butyl acrylate segments of the polymer played a major role in the formation of n‐butanol, which was mainly generated from the polymer backbone, by transfer reactions to polymer chain followed by cyclization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5838–5846, 2007 相似文献
59.
Dynamic stage repair policies where the stage repair probabilities are determined by the number of items in the buffer are examined through a model of a manufacturing system with two unreliable workstages connected by a minimal intermediate storage buffer. Definitions for workstage availability and line balance are extended for sequential manufacturing systems with dynamic repair policies. A measure for stage repair inputs and a general form of dynamic stage repair policies are presented. The steady-state probabilities of the resultant state-inhomogeneous Markov chain are computed by an efficient solution procedure. Insights obtained from extensive numerical studies are illustrated and discussed. 相似文献
60.
Jiří Herec 《Czechoslovak Journal of Physics》2004,54(12):1473-1481
In this paper the quantum-statistical properties of light beams propagating in a directional nonlinear coupler are investigated.
This device is composed of a pair of linearly coupled nonlinear waveguides operating by means of degenerate parametric downconversion.
The possibility of generation of nonclassical states of light in single and compound modes, using the short-length approximation,
is discussed. Influence of linear and nonlinear mismatches for generation of nonclassical light is taken into account.
This work was supported by Project LN00A015, Research Project No. CEZ: J14/98 and the COST project OC P11.003 of the Czech
Ministry of Education. 相似文献