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991.
992.
Let V be a star shaped region. In 2006, Colzani, Meaney and Prestini proved that if function f satisfies some condition, then the multiplier transform with the characteristic function of tV as the multiplier tends to f almost everywhere, when t goes to∞. In this paper we use a Theorem established by K.K.Chen to show that if we change their multiplier, then the condition on f can be weakened. 相似文献
993.
Ke Bo Lu 《数学学报(英文版)》2013,29(11):2181-2192
In this paper, we study the combinatorial properties ol words m chscrete dynamical systems from antisymmetric cubic maps. We also discuss the relationship of primitive kneading sequences of length n and period-doubling kneading sequences of length 2n, and then determine the number of all kneading sequences of length n. 相似文献
994.
该文把变换场理论中的变换场概念引进稳态悬浮体领域,建立了确定悬浮体的形变张量场的积分方程,在此基础上计算了稳态悬浮体的粘滞率张量,从而为进一步研究悬浮体的流变学性质开辟了一种新方法。 相似文献
995.
多物种生态竞争系统周期正解的存在性和全局吸引性 总被引:12,自引:0,他引:12
利用重合度理论中的延拓定理和Lyapunov泛函方法讨论了一类具有多个滞量的多物种生态竞争系统周期正解的存在性和全局吸引性,得到了一些新的结果.实例表明我们的结果更加广泛,更加便于应用. 相似文献
996.
997.
An autonomous stochastic predator–prey model with time delays is investigated. Almost sufficient and necessary conditions for stability in the mean and extinction of each population are established. Numerical simulations are introduced to support the results. 相似文献
998.
具无限时滞的非自治捕食者-食饵系统的持久性 总被引:16,自引:0,他引:16
本文采用新的方法研究了具无限时滞的非自治、非卷积的捕食者-食饵系统的持久性问题,得到了新的、有趣的结果。本文的结果包含已知的结果作为特例. 相似文献
999.
This paper considers a special but broad class of convex programming problems whose feasible region is a simple compact convex set intersected with the inverse image of a closed convex cone under an affine transformation. It studies the computational complexity of quadratic penalty based methods for solving the above class of problems. An iteration of these methods, which is simply an iteration of Nesterov’s optimal method (or one of its variants) for approximately solving a smooth penalization subproblem, consists of one or two projections onto the simple convex set. Iteration-complexity bounds expressed in terms of the latter type of iterations are derived for two quadratic penalty based variants, namely: one which applies the quadratic penalty method directly to the original problem and another one which applies the latter method to a perturbation of the original problem obtained by adding a small quadratic term to its objective function. 相似文献
1000.
Variational models provide reliable formulation for segmentation of features and their boundaries in an image, following the seminal work of Mumford-Shah (1989, Commun. Pure Appl. Math.) on dividing a general surface into piecewise smooth sub-surfaces. A central idea of models based on this work is to minimize the length of feature’s boundaries (i.e., H1 Hausdorff measure). However there exist problems with irregular and oscillatory object boundaries, where minimizing such a length is not appropriate, as noted by Barchiesi et al. (2010, SIAM J. Multiscale Model. Simu.) who proposed to miminize L2 Lebesgue measure of the γ-neighborhood of the boundaries. This paper presents a dual level set selective segmentation model based on Barchiesi et al. (2010) to automatically select a local feature instead of all global features. Our model uses two level set functions: a global level set which segments all boundaries, and the local level set which evolves and finds the boundary of the object closest to the geometric constraints. Using real life images with oscillatory boundaries, we show qualitative results demonstrating the effectiveness of the proposed method. 相似文献