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81.
82.
本文结合次梯度选取技术及割平面法和强次可行方向法的思想,提出了一个求解目标函数非光滑约束优化问题的强次可行方向算法.通过设计一个新的寻找搜索方向子问题和构造新型线搜索,算法不仅能接受不可行的初始点,而且能保持迭代点的强次可行性,同时避免在可行域外目标函数值的不适度增加.算法具备全局收敛性,且初步的数值试验表明算法是稳定有效的. 相似文献
83.
V. Lepiller A. Goharzadeh A. Prigent I. Mutabazi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):445-455
We have investigated the influence of a weak radial
temperature gradient in a wide gap and large aspect ratio
Couette-Taylor system. The inner cylinder is rotating and can be
heated or cooled, the outer cylinder is at rest and immersed in a
large thermal bath. We found that a radial temperature gradient
destabilizes the Couette flow leading to a pattern of traveling
helicoidal vortices occurring only near the bottom of the system.
The size of the pattern increases as the rotation frequency of the cylinder is increased. We
have characterized the spatiotemporal properties of the pattern and we have shown that it
behaves as a wall mode found in the simulation of the
complex Ginzburg-Landau equation with homogeneous boundary
conditions. 相似文献
84.
This paper investigates a genotype selection model subjected to both a multiplicative coloured noise and an additive coloured noise with different correlation time τ1 and τ2 by means of the numerical technique. By directly simulating the Langevin Equation, the following results are obtained. (1) The multiplicative coloured noise dominates, however, the effect of the additive coloured noise is not neglected in the practical gene selection process. The selection rate μ decides that the selection is propitious to gene A haploid or gene B haploid. (2) The additive coloured noise intensity and the correlation time τ2 play opposite roles. It is noted that α and τ2 can not separate the single peak, while can make the peak disappear and ~-2 can make the peak be sharp. (3) The multiplicative coloured noise intensity D and the correlation time τ1 can induce phase transition, at the same time they play opposite roles and the reentrance phenomenon appears. In this case, it is easy to select one type haploid from the group with increasing D and decreasing τ1. 相似文献
85.
86.
In this paper, the idea of random selection in the theorem on gambling system is extended to Markov chains, by using the notion likelihood ratio and an analytic technique. A strong limit theorem on the relative frequency of ordered couple under random selection is established.AMS Subject Classification (2001)
primary 60F15 Secondary 60J10 相似文献
87.
In this paper, we derive a stochastic model for the HIV epidemic in homosexual populations involving age and race. To account for effects of different mixing patterns, a low risk selection rule is introduced. The model is then formulated in terms of chain multinomial distributions by means of which the means are derived. Some simulation studies by computer indicate clearly that age and race have a significant impact on the HIV epidemic. 相似文献
88.
Luc Chapleau Jacques-A. Ferland Jean-Marc Rousseau 《European Journal of Operational Research》1985,20(1):48-57
This paper introduces a new approach for generating school bus routes in a dense urban area. First, a districting algorithm is used to determine clusters including appropriate numbers of students. Then, for each cluster, a route and the stops along this route are determined. Numerical results are reported and compared with those obtained previously. Although the algorithm has been developped and tested in a specific context, it could easily be extended to more general vehicle routing problems. 相似文献
89.
A model for polar filaments interacting via molecular motor complexes is investigated which exhibits bifurcations to spatial
patterns. It is shown that the homogeneous distribution of filaments, such as actin or microtubules, may become either unstable
with respect to an orientational instability of a finite wave number or with respect to modulations of the filament density,
where long-wavelength modes are amplified as well. Above threshold nonlinear interactions select either stripe patterns or
periodic asters. The existence and stability ranges of each pattern close to threshold are predicted in terms of a weakly
nonlinear perturbation analysis, which is confirmed by numerical simulations of the basic model equations. The two relevant
parameters determining the bifurcation scenario of the model can be related to the concentrations of the active molecular
motors and of the filaments, respectively, which both could be easily regulated by the cell. 相似文献
90.
In this paper we consider a problem of distance selection in the arrangement of hyperplanes induced by n given points. Given a set of n points in d-dimensional space and a number k,
, determine the hyperplane that is spanned by d points and at distance ranked by k from the origin. For the planar case we present an O(nlog2n) runtime algorithm using parametric search partly different from the usual approach [N. Megiddo, J. ACM 30 (1983) 852]. We establish a connection between this problem in 3-d and the well-known 3SUM problem using an auxiliary problem of counting the number of vertices in the arrangement of n planes that lie between two sheets of a hyperboloid. We show that the 3-d problem is almost 3SUM-hard and solve it by an O(n2log2n) runtime algorithm. We generalize these results to the d-dimensional (d4) space and consider also a problem of enumerating distances. 相似文献