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121.
D.H. Zanette 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(3):537-541
A system of globally coupled maps whose synchronized dynamics differs from the individual (chaotic) evolution is considered.
For nonchaotic synchronized dynamics, the synchronized state becomes stable at a critical coupling intensity lower than that
of the fully chaotic case. Below such critical point, synchronization is also stable in a set of finite intervals. Moreover,
the system is shown to exhibit multistability, so that even when the synchronized state is stable not all the initial conditions
lead to synchronization of the ensemble.
Received 22 October 1999 相似文献
122.
The α-phase in Zr-2.5 Nb pressure tubes has been analysed after irradiation with neutrons for temperatures between 523 and 573 K. The α-phase contains Nb in supersaturated solid solution (about 0.5−1 wt% Nb) in the as-fabricated condition. Irradiation results in the formation of small discrete precipitates having diameters of about 5 nm. Energy Dispersive X-ray (EDX) analysis using a scanning transmission electron microscope (STEM) was complicated by the presence of a self-generated X-rays in the irradiated material and by the fact that the precipitates were small relative to the foil thickness (typically 100–200 nm). Techniques developed to measure segregation of impurities at interfaces were employed to show that the precipitates were Nb-rich, their formation being consistent with a decrease in Nb concentration in the matrix. 相似文献
123.
This article is intended for investigating the effects of magnetohydrodynamics (MHD) and volume fraction of carbon nanotubes (CNTs) on the flow and heat transfer in two lateral directions over a stretching sheet. For this purpose, three types of base fluids specifically water, ethylene glycol and engine oil with single and multi-walled carbon nanotubes are used in the analysis. The convective boundary condition in the presence of CNTs is presented first time and not been explored so far. The transformed nonlinear differential equations are solved by the Runge–Kutta–Fehlberg method with a shooting technique. The dimensionless velocity and shear stress are obtained in both directions. The dimensionless heat transfer is determined on the surface. Three different models of thermal conductivity are comparable for both CNTs and it is found that the Xue [1] model gives the best approach to guess the superb thermal conductivity in comparison with the Maxwell [2] and Hamilton and Crosser [3] models. And finally, another finding suggests the engine oil provides the highest skin friction and heat transfer rates. 相似文献
124.
Rosângela S. do Nascimento 《Physica A》2010,389(9):1869-1873
In this work, we apply Detrended Fluctuation Analysis (DFA) to study the dynamics of electrical cortical activity in rats during the phenomenon of Cortical Spreading Depression (CSD), as well as the periods before and after this phenomenon. The characteristic of CSD is reduced electrical activity that occurs and spreads in the cerebral cortex after the application of electrical, chemical or mechanical stimulus. Our results show that the electrocorticogram signal shows long range temporal correlations and scaling behavior, except during the pre-CSD burst phase (significant increase of amplitude provoked by stimulus). 相似文献
125.
The effects of finite grid resolution on the statistics of small scales in direct numerical simulations of turbulent mixing of passive scalars are addressed in this paper. Simulations at up to 20483 grid points with grid spacing Δx varied from about 2 to 1/2 Batchelor scales (ηB) show that most conclusions on Schmidt number (Sc) dependence from prior work at less stringent resolution remain qualitatively correct, although simulations at resolution Δx≈ηB are preferred and will give adequate results for many important quantities including the scalar dissipation intermittency exponent and structure functions at moderately high orders. For Sc≥1, since ηB=ηSc−1/2 (where η is the Kolmogorov scale), the requirement Δx≈ηB is more stringent than the corresponding criterion Δx≈η for the velocity field, which is thus well resolved in simulations aimed at high Schmidt number mixing. A simple argument is given to help interpret the effects of Schmidt and Reynolds numbers on trends towards local isotropy and saturation of intermittency at high Schmidt number. The present results also provide evidence for a trend to isotropy at high Reynolds number with fixed Sc=1.0. This is a new observation apparently not detected in less well resolved simulations in the past, and will require further investigation in the future. 相似文献
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128.
极谱分析法连续测定痕量铅和镉 总被引:13,自引:0,他引:13
研究了 Pb2 + 和 Cd2 + 与 KCl-酒石酸钠 -三乙醇胺 -明胶体系的二次导数极谱波。在 p H=4 .5的 HAc-Na Ac介质中 ,Pb2 + 和 Cd2 + 分别于 - 0 .4 6 V和 - 0 .6 4V电位处产生一良好的极谱波。峰电流与 Pb2 + 和Cd2 + 的浓度分别在 1× 10 -5— 3× 10 -1g· L-1和 5× 10 -5— 6× 10 -3 g· L-1范围内呈线性关系。 Pb2 + 和Cd2 +的检出限分别为 1× 10 -7g·L-1和 5× 10 -7g·L-1。本法准确、简便、快速、选择性高。已直接用于饮料中铅和镉的连续测定 ,同时也对酒及面粉样品进行了测定 ,回收率分别为 99.9%— 10 0 .1%和 97.0 %—10 4 .8%。 相似文献
129.
极紫外光刻系统物镜光学元件的支撑与分析 总被引:1,自引:0,他引:1
介绍了极紫外光刻系统物镜光学元件的支撑原理和支撑要求,分析了符合运动学支撑要求的物镜支撑结构和面形检测用支撑结构;针对支撑结构性能和支撑方案中关键问题进行了深入研究,并提出了相应的解决方案。最后建立了支撑结构的有限元模型,并在此基础上进行了重力场中的镜体变形分析和温度场作用下系统的热变形分析。分析结果表明,检测用支撑与实际用支撑两种结构在重力环境下支撑出的元件面形基本相同,面形相差0.0026nm(RMS);温控范围为0.05℃时,由机械结构热变形引起的镜体面形变化在0.001nm(RMS)量级。研究结果表明,运动学物镜元件支撑结构能够满足极紫外光刻系统对于物镜机械支撑结构的要求。 相似文献
130.