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1.
D. Merritt 《Celestial Mechanics and Dynamical Astronomy》1996,64(1-2):55-67
Recent results on chaos in triaxial galaxy models are reviewed. Central mass concentrations like those observed in early-type galaxies - either stellar cusps, or massive black holes — render most of the box orbits in a triaxial potential stochastic. Typical Liapunov times are 3–5 crossing times, and ensembles of stochastic orbits undergo mixing on timescales that are roughly an order of magnitude longer. The replacement of the regular orbits by stochastic orbits reduces the freedom to construct self-consistent equilibria, and strong triaxiality can be ruled out for galaxies with sufficiently high central mass concentrations. 相似文献
2.
风浪宏观特征量是描述风浪场特征的重要物理量。作者基于风浪有停留在混乱运动状态的趋势的性质对风浪场特征量间的关系进行了研究。主频波频率附近的波动自风摄取能量,风浪吸收的能量通过非线性相互作用在谱中重新分配。谱中能量的重新分配产生多尺度波动,这导致风浪波面的混乱运动(风浪处于混乱运动状态)。在稳定状态,风浪运动最为混乱。当风浪状态偏离最混乱运动状态,谱中非线性相互作用引起的能量重新分配将使风浪回到该状态。基于线性海浪理论导出风浪场特征量间的关系。导出的关系与观测结果进行了对比,发现理论结果与观测结果很好地符合。风浪场宏观特征量间存在固有关系。尽管目前风浪场特征量关系的观测结果存在差异,但本文中证明,所导出的理论关系与实验结果很好地符合。 相似文献
3.
In this contribution, we present a virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical
simulations with the aim to highlight the power of 3D representations in the understanding of this geological phenomenon.
In particular, samples of mixed juveniles from Salina island (Southern Italy) are reconstructed in 3D by serial lapping and
digital montage and numerical simulations are performed by using a 3D chaotic dynamical system. Natural and simulated magma
mixing structures are visualized by using several multimedia tools including animations and “virtual reality” models. It is
shown that magma interaction processes can generate large spatial and temporal compositional heterogeneities in magmatic systems.
The same topological structures are observed in both 3D reconstructed rock samples and chaotic numerical simulations, indicating
that the mixing of magmas is governed by chaotic dynamics. The use of 3D multimedia models gives the opportunity to penetrate
into magma mixing structures and to understand their significance in the context of magma dynamics. Such an approach is very
powerful since multimedia tools can strongly capture the attention of the reader bringing him/her into an interactive and
memorable geological experience.
Electronic supplementary material enclosed: 相似文献
4.
岩石断裂作用的复杂性和混沌动力学 总被引：1，自引：0，他引：1
断裂是一个复杂的动力学体系,受到岩石结构、反应、流体迁移、应力、岩石变形和力学等多种地质因素和过程的耦合控制。本文建立了断裂体系的反应-输运-力学耦合动力学模型并编制了模拟程序。以湖南水口山矿区为例,通过动力学模拟表明不同地层岩性的断裂渗透率大小和演化特征存在显著差异,断裂作用促使岩石渗透率的空间非均匀性增强,从而有利于流体的局部汇聚和矿体的形成。断裂中压力随时间呈现出非周期振荡变化,反映了断裂演化的混沌特征。 相似文献
5.
本文在正压涡度方程中引进短时间尺度周期性热力强迫项。在一定的参数范围内,该强迫项可以引起环流指数准两至三周的低频振荡。 相似文献
6.
7.
混沌系统的局域特征与可预报性 总被引：1，自引：0，他引：1
讨论了混沌系统的时间和空间的局域特征。首先分析了研究时间和空间局域特征的必要性。接着引进了有限时间不稳定和局域时间不稳定的概念，并对有关的计算问题进行了研究。对Ｌｏｒｅｎｚ系统的具体计算表明，随着轨线在混沌吸引子上的演变，局域不稳定特征有很大的变化，相应误差增长也有很大的变化。相应于误差迅速增长的轨线部分局限于很有限的相空间范围内，而且同误差增长缓慢的轨线部分占据的相空间区域截然可分。每一个例的可预报性依赖于轨线在相空间中所处的区域。混沌系统的这种局域特征可以是导致个例业务预报技巧之间有很大差别的主要原因。 相似文献
8.
Abedalrazq F. Khalil Mac McKeeMariush Kemblowski Tirusew AsefaLuis Bastidas 《Advances in water resources》2006
Sparse learning machines provide a viable framework for modeling chaotic time-series systems. A powerful state-space reconstruction methodology using both support vector machines (SVM) and relevance vector machines (RVM) within a multiobjective optimization framework is presented in this paper. The utility and practicality of the proposed approaches have been demonstrated on the time series of the Great Salt Lake (GSL) biweekly volumes from 1848 to 2004. A comparison of the two methods is made based on their predictive power and robustness. The reconstruction of the dynamics of the Great Salt Lake volume time series is attained using the most relevant feature subset of the training data. In this paper, efforts are also made to assess the uncertainty and robustness of the machines in learning and forecasting as a function of model structure, model parameters, and bootstrapping samples. The resulting model will normally have a structure, including parameterization, that suits the information content of the available data, and can be used to develop time series forecasts for multiple lead times ranging from two weeks to several months. 相似文献
9.
J. C. Muzzio 《Celestial Mechanics and Dynamical Astronomy》2006,96(2):85-97
We created a self-consistent triaxial stellar system through the cold disipationless collapse of 100,000 particles whose evolution was followed with a multipolar code. The resulting system rotates slowly even though its total angular momentum is zero, i.e., it offers an example of figure rotation. The potential of the system was subsequently approximated with interpolating formulae yielding a smooth potential stationary in the rotating frame. The Lyapunov exponents could then be computed for a randomly selected sample of 3,472 of the bodies that make up the system, allowing the recognition of regular and partially and fully chaotic orbits. The regular orbits were Fourier analyzed and classified using their locations on the frequency map. A comparison with a similar non-rotating model showed that the fraction of chaotic orbits is slightly but significantly enhanced in the rotating model; alternatively, there are no significant differences between the corresponding fractions neither of partially and fully chaotic orbits nor of long axis tubes, short axis tubes, boxes and boxlets among the regular orbits. This is a reasonable result because the rotation causes a breaking of the symmetry that may increase chaotic effects, but the rotation velocity is probably too small to produce any other significant differences. The increase in the fraction of chaotic orbits in the rotating system seems to be due mainly to the effect of the Coriolis force, rather than the centrifugal force, in good agreement with the results of other investigations. 相似文献
10.
Chandima Gomes Vernon Cooray Mahendra Fernando Raul Montano Upul Sonnadara 《Journal of Atmospheric and Solar》2004,66(18):428
Pulse trains of irregular pulse characteristics and erratic amplitudes are observed in lightning flashes. These are termed “chaotic pulse trains” in this study. The average width of the individual pulses of these pulse trains is in the range of a few microseconds, with the lower limit of individual measurements extending into the sub-microsecond region. The typical pulse separation lies in the range of 2–. The pulse duration shows a consistent distribution with the most probable value at 400–. Chaotic pulse trains occur most often immediately prior to subsequent strokes. However, they occur also a few milliseconds to several tens of milliseconds prior to return strokes and sometimes do not precede return strokes at all. Twenty-six percent of the total subsequent strokes recorded in this study were preceded by chaotic pulse trains. A few of these pulse trains have occurred in a sequence of several tens of millisecond intervals in between return strokes. We have also found them to occur within very intense cloud flashes. These chaotic pulse trains have features that are different from those of other known pulse trains reported in the lightning literature. Hence, they may be caused by a physical process that has not yet been identified. 相似文献