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考虑一类具梯度源项的非散度型抛物方程解的熄灭行为,获得了解的临界熄灭指数,同时,给出了熄灭解的指数衰减估计. 相似文献
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研究奇异非线性边界流耦合热方程组的有限时刻熄灭问题. 给出区分同时与非同时熄灭的准则,然后 特别得到不同非线性指标区域和适当初值条件的3类同时熄灭速率. 推广了Pablo, Quirós 和 Rossi 关于内部吸收项耦合热方程组齐次Neumann边值条件下有限时刻熄灭问题的原有工作. 相似文献
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本文研究一类具有变指标的反应扩散方程组的非齐次第一初边值问题.通过利用多个变指标的最大值给出方程组问题熄灭解的两个分量发生同时或非同时熄灭的最优判据,继而给出熄灭速率. 相似文献
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该文研究一带时滞的退化非线性抛物方程的初边值问题。运用正则化方法和上下解技巧证明了上述问题的古典正解的局部存在性及其可延拓性。讨论了整体存在性和 有限时刻熄灭,建立了临界长度,得到了熄灭点的位置以及特殊f(u)情形下的熄灭速率估计。 相似文献
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本文研究一类带奇异项的拟线性抛物方程的初边值问题.得到了古典解的熄灭现象,并对熄灭解的渐近行为作了分析,包含了[2-5]的相应结论 相似文献
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本文研究一类带奇异项的一性抛物方程的初边值问题,得到了古典解的熄灭现象,并对熄灭解的渐近行为作了分析,包含了(2-5)的相应结论。 相似文献
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本文从医院管理实际出发,研究和探索了时间顺序预测,因果预测和预报性预测这三种分别适用于短期,中期和长期的科学预测方法。它在我国医院管理中具有实际的指导意义。 相似文献
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Consider a real-valued and second-order stationary time series with mean zero. The aim is to estimate its spectral density. A minimax solution of this problem is known when either the time series is observed directly, or some observations are missed according to an independent Bernoulli process, or for some special cases when the time series is multiplied by an amplitude-modulating time series with known distribution. It is shown that if a time series of interest, a Bernoulli time series defining missing mechanism, and an amplitude-modulating time series are mutually independent, then the shape of spectral density of an underlying time series of interest can be estimated with the minimax rate known for the case of direct observations. Furthermore, in some special cases the spectral density can be estimated with the minimax rate known for directly observed time series of interest. 相似文献
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In this article, we propose a novel method for transforming a time series into a complex network graph. The proposed algorithm is based on the spatial distribution of a time series. The characteristics of geometric parameters of a network represent the dynamic characteristics of a time series. Our algorithm transforms, respectively, a constant series into a fully connected graph, periodic time series into a regular graph, linear divergent time series into a tree, and chaotic time series into an approximately power law distribution network graph. We find that when the dimension of reconstructed phase space increases, the corresponding graph for a random time series quickly turns into a completely unconnected graph, while that for a chaotic time series maintains a certain level of connectivity. The characteristics of the generated network, including the total edges, the degree distribution, and the clustering coefficient, reflect the characteristics of the time series, including diverging speed, level of certainty, and level of randomness. This observation allows a chaotic time series to be easily identified from a random time series. The method may be useful for analysis of complex nonlinear systems such as chaos and random systems, by perceiving the differences in the outcomes of the systems—the time series—in the identification of the systemic levels of certainty or randomness. © 2011 Wiley Periodicals, Inc. Complexity, 2011 相似文献
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金霁 《数学的实践与认识》2012,42(10):222-229
研究工件加工时间是开工时间的线性分段函数的单机排序问题,其中工件的加工时间是开工时间的线性增加函数,但是有一个上界,在时刻T(T是已知常数)以后开始加工的工件,其加工时间不再因开工时间的推迟而增大,优化的目标是极小化总误工工件数.当工件的工期与加工时间满足某种一致性关系的时候,不管工件的加工时间是开工时间的简单线性分段函数,还是其基本加工时间是与恶化率有关的分段线性函数,证明这两种情况都是多项式时间可解的. 相似文献
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William G. Gray Julia C. Muccino 《Numerical Methods for Partial Differential Equations》2000,16(3):312-326
Multivalue methods are a class of time‐stepping procedures for numerical solution of differential equations that progress to a new time level using the approximate solution for the function of interest and its derivatives at a single time level. The methods differ from multistep procedures, which make use of solutions to the differential equation at multiple time levels to advance to the new time level. Multistep methods are difficult to employ when a change in time‐step is desired, because the standard formulas (e.g., Adams‐Moulton or Gear) must be modified to accommodate the change. Multivalue methods seem to possess the desirable feature that the time‐step may be changed arbitrarily as one proceeds, since the solution proceeds from a single time level. However, in practice, changes in the time‐step introduce lower order errors or alter the coefficient in the truncation error term. Here, the multivalue Adams‐Moulton method is presented based on a general interpolation procedure. Modifications required to retain the high‐order accuracy of these methods during a change in time‐step are developed. Additionally, a formula for the unknown initial derivatives is presented. Finally, two examples are provided to illustrate the potential merit of the modification to the standard multivalue methods. © 2000 John Wiley & Sons, Inc. Numer Methods Partials Differential Eq 16: 312–326, 2000 相似文献
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Peter E. Kloeden 《Journal of Difference Equations and Applications》2013,19(3-4):357-368
Dynamical equations on time scales typically generate a nonautonomous process, even when the vector field function does not depend explicitly on time. Nonautonomous pullback attractors are thus the appropriate generalisation of autonomous attractors to time scale dynamics. The existence of a pullback attractor follows when the process has a pullback absorbing set. Assuming that a dynamical equation over a given time scale which has no rapidly increasing gaps satisfies a certain dissipativity condition, and thus possesses a pullback attractor, and that its solutions depend uniformly on initial data including the time scale, it is shown that the same dynamical equation over nearby time scales also has a pullback attractor, whose component sets converge upper semicontinuously to the corresponding component sets of the pullback attractor of the original system. 相似文献
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We consider a model system of two inhomogeneous nonlinear Sobolev-type equations of sixth order with second-order time derivative and prove the local (with respect to time) solvability of the problem. We state conditions under which the blow-up of the solution occurs in finite time and find an upper bound for the blow-up time. 相似文献