具有频率依赖性耦合的神经振子群相响应同步

考虑频率依赖性耦合神经振子群在外部谐波刺激下的动力学模型,引入相位概率密度函数导出序参数的演化方程.数值模拟结果表明,当固有频率的众数较低时,频率依赖性耦合对神经振子群相响应同步无显著影响;而当固有频率的众数较高时,频率依赖性神经振子群在外部弱刺激下几乎达到完全相位同步,随着刺激强度的增加转为无规则的振荡,最终达到同步周期振荡.     

On the Average Distribution of Inversive Pseudorandom Numbers

The inversive congruential method is an attractive alternative to the classical linear congruential method for pseudorandom number generation. The authors have recently introduced a new method for obtaining nontrivial upper bounds on the multidimensional discrepancy of inversive congruential pseudorandom numbers in parts of the period. This method has also been used to study the multidimensional distribution of several other similar families of pseudorandom numbers. Here we apply this method to show that, “on average” over all initial values, much stronger results than those known for “individual” sequences can be obtained.     

Ranking Functions Induced by Weighted Average of Fuzzy Numbers

In this paper we present two definitions of possibilistic weighted average of fuzzy numbers, and by them we introduce two different rankings on the set of real fuzzy numbers. The two methods are dependent on several parameters. In the first case, the parameter is constant and the results generalize what Carlsson and Fuller have obtained in (2001). In the second case, the parameter is a function, not fixed a priori by the decision maker, but it depends on the position of the interval on the real axe. In all the two cases we call the parameter degree of risk, which takes into account of a risk-tendency or aversion of the decision maker.     

Average Linking Numbers of Closed Orbits of Hyperbolic Flows

The existence of an asymptotic average of linking numbers ofperiodic orbits of a basic set of an Axiom A flow in S³ or R³is proved.     

Average Root Numbers for a Nonconstant Family of Elliptic Curves

We give some examples of families of elliptic curves with nonconstant j-invariant where the parity of the (analytic) rank is not equidistributed among the fibres.     

具有不同耦合强度且带有时滞的振子网络上的同步

本文研究了具有不同耦合强度且带有时滞的振子网络上的同步问题．我们给出了该网络同步状态的稳定性准则，证实了其同步状态的稳定性与网络的拓扑性无关．最后，通过数值模拟验证了我们的理论结果．     

Quadrangulations on 3-Colored Point Sets with Steiner Points and Their Winding Numbers

Let P be a point set on the plane, and consider whether P is quadrangulatable, that is, whether there exists a 2-connected plane graph G with each edge a straight segment such that V(G) = P, that the outer cycle of G coincides with the convex hull Conv(P) of P, and that each finite face of G is quadrilateral. It is easy to see that it is possible if and only if an even number of points of P lie on Conv(P). Hence we give a k-coloring to P, and consider the same problem, avoiding edges joining two vertices of P with the same color. In this case, we always assume that the number of points of P lying on Conv(P) is even and that any two consecutive points on Conv(P) have distinct colors. However, for every k ≥ 2, there is a k-colored non-quadrangulatable point set P. So we introduce Steiner points, which can be put in any position of the interior of Conv(P) and each of which may be colored by any of the k colors. When k = 2, Alvarez et al. proved that if a point set P on the plane consists of \({\frac{n}{2}}\) red and \({\frac{n}{2}}\) blue points in general position, then adding Steiner points Q with \({|Q| \leq \lfloor \frac{n-2}{6} \rfloor + \lfloor \frac{n}{4} \rfloor +1}\) , P ∪ Q is quadrangulatable, but there exists a non-quadrangulatable 3-colored point set for which no matter how many Steiner points are added. In this paper, we define the winding number for a 3-colored point set P, and prove that a 3-colored point set P in general position with a finite set Q of Steiner points added is quadrangulatable if and only if the winding number of P is zero. When P ∪ Q is quadrangulatable, we prove \({|Q| \leq \frac{7n+34m-48}{18}}\) , where |P| = n and the number of points of P in Conv(P) is 2m.     

分形花及其网络上的平均测地距离

借助圆周映射计算距离函数在自相似测度上的积分,本文利用自相似测度得到分形花上的平均测地距离,并将此结果应用于分形花网络.     

三角模糊数的加权平均及其在评价决策中的应用

定义了满足权重要求的模糊权重向量,利用三角模糊数的截集,给出了模糊加权平均数的计算原理、步骤和一种简便的近似方法。当评价值与权重表达成三角模糊数时,运用该方法可以使决策以及评价对象本身所具有的模糊性有效地利用起来进行综合评价。最后给出了一个算例。     

固定合作规模网络的平均路径长度

本文提出了一种特殊的合作网络,称之为固定合作规模网络．我们重点研究了这类网络的平均路径长度,通过建立微分方程,得到平均路径长度的增加速度近似与网络规模的对数成正比．     

Phase Transition and Eigenvalue Degeneracy of a One Dimensional Anharmonic Oscillator

For a one dimensional lattice model with long range exponential interaction the problem of deriving the thermodynamic properties of the system reduces to the problem of determining the spectrum of a differential equation for a one dimensional anharmonic oscillator with potential αx² + βγx⁴ where γ is the inverse of the range of the interaction and α is a function of temperature which is positive at high temperatures and negative at low temperatures. It is proved that at low temperatures, α < 0, and in the limit γ → 0, (corresponding to an infinitely long range interaction) the spectrum becomes asymptotically degenerate. The relation of degeneracy to the occurrence of a phase transition is discussed and the generalization to higher dimensions is mentioned briefly.     

超立方体网络的(d,k)控制数

(d,k)控制数是刻画容错网络中资源共亨可靠性的一个新参数.本文考虑了k维超立方体Qk的(d,k)控制数,得到:γ1,k(Qk)=2k-1(k>1);d=[k/2] 1(k>2)时,γd,k(Qk)=2;d≤[k/2](k≥4)时,3≤γd,k(Qk)≤2k-d 1;以及若d为正整数,且[k/d]=[k/(d-1)] 1,则γd,k(Qk)=γd,k(Qk),其中[k/d].d 1≤k1≤k.     

On the Average Discrepancy of Successive Tuples of Pseudo-Random Numbers over Parts of the Period

 In the present paper we give an upper and a lower bound for the average value of the discrepancy of non-overlapping s-tuples of successive elements of a first order congruential pseudo-random-number generator (with prime modulus and maximal period). The estimates are – up to logarithmic factors – sharp also for short parts of the period. Received 30 January 1997; in revised form 2 May 1997     

一致有界树指标马氏链的层频率的强大数定律

利用一致有界树指标马氏链的强大数定律,给出了一致有界树指标马氏链的关于状态和状态序偶出现的层频率的强大数定律.     

论平均预期寿命与平均死亡年龄

首先回顾了平均预期寿命和平均死亡年龄的定义,并总结了当前文献中提到的两者的区别,就其中存在的问题提出了质疑,并以中国人寿保险业经验生命表和中国企业生命表为例,验证了平均预期寿命与平均死亡年龄在数值上是一样的,并在理论上做了证明.结论是两者并不是"有本质区别的"并且两者都会受到死亡年龄结构的影响,同时得到了,平均剩余寿命加上年龄区间的下限值就等于该年龄人口的平均死亡年龄.     

关于可列马氏链状态出现频率延迟平均的强大数定律

对于齐次马氏链由有限状态推广到可列的情形,由于可列和与极限运算不能交换,与文中证明方法与有限情形不同.利用了二元函数延迟平均的强极限定理和条件期望的平滑性,研究可列齐次马氏链状态出现频率延迟平均的强大数定律.     

Designing Heteroclinic and Excitable Networks in Phase Space Using Two Populations of Coupled Cells

We give a constructive method for realising an arbitrary directed graph (with no one-cycles) as a heteroclinic or an excitable dynamic network in the phase space of a system of coupled cells of two types. In each case, the system is expressed as a system of first-order differential equations. One of the cell types (the p-cells) interacts by mutual inhibition and classifies which vertex (state) we are currently close to, while the other cell type (the y-cells) excites the p-cells selectively and becomes active only when there is a transition between vertices. We exhibit open sets of parameter values such that these dynamical networks exist and demonstrate via numerical simulation that they can be attractors for suitably chosen parameters.