Partial extinction,permanence and global attractivity in nonautonomous <Emphasis Type="Italic">n</Emphasis>-species Lotka-Volterra competitive systems with impulses

In this paper, the qualitative properties of general nonautonomous Lotka-Volterra n-species competitive systems with impulsive effects are studied. Some new criteria on the permanence, extinction and global attractivity of partial species are established by used the methods of inequalities estimate and Liapunov functions. As applications, nonautonomous two species Lotka-Volterra systems with impulses are discussed.     

基于灰色聚类分析的企业应急管理能力评价

在对企业应急管理能力概念初步界定的基础上,建立企业应急管理能力评价指标体系,针对企业应急管理能力多指标综合评价中存在的主观性问题,依据灰色聚类原理,提供了一种计算各指标权重的方法,使得指标之间的权重在评价过程中自动产生,不需要经过人为判断,减少了评价过程中的主观因素.结合实例企业,通过专家对各指标进行评估打分,根据评价...     

基于辩论的多agent商务谈判辩论产生和决策过程研究

由于在自动谈判中加入辩论成分能够允许Agent在谈判过程中通过辩论的形式交换和交流额外的信息,进而影响对方的信念、偏好、意向或目标,使谈判向着有利于达成协议方向发展,并提高谈判效率,降低交易成本,因此已经成为多Agent商务谈判领域的热点发展方向.本文针对如何产生辩论这一重要问题进行研究,提出了"候选辩论集的产生策略"和"基于冲突分析的辩论目标产生模型",分析了基于辩论的多Agent商务谈判决策过程,并通过原型系统进行了验证.本文的研究成果将促使多Agent商务谈判系统向着更为实用方向发展.     

RCMARS: Robustification of CMARS with different scenarios under polyhedral uncertainty set

Our recently developed CMARS is powerful in handling complex and heterogeneous data. We include into CMARS the existence of uncertainty about the scenarios. Indeed, data include noise in both output and input variables. Therefore, solutions of the optimization problem may reveal a remarkable sensitivity to perturbations in the parameters of the problem. The data uncertainty results in uncertain constraints and objective function. To overcome this difficulty, we refine our CMARS algorithm by a robust optimization technique proposed to cope with data uncertainty. In our previous study, we present the new robust CMARS (RCMARS) in theory and method and illustrate it with a numerical example. In this study, we present RCMARS results with different uncertainty scenarios for our numerical example.     

A delay digestion process with application in a three-species ecosystem

In a natural ecosystem, specialist predators feed almost exclusively on one specific species of prey which may be possible for a parasitoid. But generalist predators feed on many types of species. It is also well known that the predation rate increases as prey density rises, but eventually levels off due to the predator’s handling time. The response function, thereby, is often assumed to Holling II functional response. In addition, digestion processes of the predation often involve reactions with delays. In view of these facts, a three-species ecosystem with a delay digestion process and Holling functional response is formulated. By analyzing the corresponding characteristic equations, the stability of the equilibria is investigated. Furthermore, Hopf bifurcations occurring at the positive equilibrium under some conditions are demonstrated. The consequence of global stability of the positive equilibrium is that predation will not irreversibly change the system. That is, as long as preys are not made extinct by excessive predation of their predator, the system is able to recover. Numerical simulations are carried out to illustrate our theoretical results. Meanwhile, they indicate that time delay is harmless for permanence of populations even thought it has a tendency to produce oscillations.     

The variational iteration method for solving nonlinear singular boundary value problems arising in various physical models

In this paper, the variational iteration method (VIM) is used to study a nonlinear singular boundary value problems arising in various physical equations. The VIM overcomes the singularity issue at the origin x = 0. The Lagrange multipliers for all four cases of the boundary value problems are formally derived. The variational iteration method is tested for its efficiency and reliability.     

奇素数幂中的优美指数猜想

对于不小于7素数p,设1≤k≤p-1,则使用同余方法可证明方程n=pkp-1d（n）无正整数解,从而pkp-1不是优美指数,进而可以肯定＂存在无穷多个正整数不是优美指数＂.     

Dini定理修正

讨论经典Dini定理,证明当Dini定理的连续性条件被放宽成"un(x)一u(x)有最大值"时,同样可以得到一致收敛的结论.在函数项级数和含参变量积分中,Dini定理可以进行类似的修改.最后,给出修正后的Dini定理的一个具体应用.     

Robust multigrid preconditioners for the high‐contrast biharmonic plate equation

We study the high‐contrast biharmonic plate equation with Hsieh–Clough–Tocher discretization. We construct a preconditioner that is robust with respect to contrast size and mesh size simultaneously based on the preconditioner proposed by Aksoylu et al. (Comput. Vis. Sci. 2008; 11 :319–331). By extending the devised singular perturbation analysis from linear finite element discretization to the above discretization, we prove and numerically demonstrate the robustness of the preconditioner. Therefore, we accomplish a desirable preconditioning design goal by using the same family of preconditioners to solve the elliptic family of PDEs with varying discretizations. We also present a strategy on how to generalize the proposed preconditioner to cover high‐contrast elliptic PDEs of order 2k, k>2. Moreover, we prove a fundamental qualitative property of the solution to the high‐contrast biharmonic plate equation. Namely, the solution over the highly bending island becomes a linear polynomial asymptotically. The effectiveness of our preconditioner is largely due to the integration of this qualitative understanding of the underlying PDE into its construction. Copyright © 2010 John Wiley & Sons, Ltd.     

A bargaining set for monotonic simple games based on external and internal stability

A new bargaining set based on notions of both internal and external stability is developed in the context of endogenous coalition formation. It allows one to make an explicit distinction between within-group and outside-group deviation options. This type of distinction is not present in current bargaining sets. For the class of monotonic proper simple games, the outcomes in the bargaining set are characterized. Furthermore, it is shown that the bargaining set of any homogeneous weighted majority game contains an outcome for which the underlying coalition structure consists of a minimal winning coalition and its complement.