EKELAND'S VARIATIONAL PRINCIPLE AND CARISTI'S FIXED POINT THEOREM IN PROBABILISTIC METRIC SPACE

The main purpose of this paper is to establish the Ekeland's variational principle andCaristi's fixed point theorem in probabilistic metric spaces and to give a direct simple proofof the equivalence between these two theorems in the probabilistic metric space. The resultspresented in this paper generalize the corresponding results of [9--12].     

具有N—策略休假的M／G／1排除的同分解与最优策略

本文利用向量Ｍａｒｋｏｖ过程方法，研究了具有Ｎ－策略休假且休假时间为一般分布的Ｍ／Ｇ／１排队。它的两种特殊情况分别是具有多重休假的Ｍ／Ｇ／１排队和具有Ｎ－策略控制的Ｍ／Ｇ／１排队。     

服务台可修的M/G(E_k/H)/1排队系统的统计平衡理论

在随机运筹学中,排队模型和可靠性模型是研究得较多的两大模型,但两者相结合的模型却只有极少数文章研究过。然而,实践中却经常会遇到这类服务台可修的排队模型。这样,无论从排队论角度还是从可靠性角度都很有必要进行深入研究。这种相结合的模型在理论上会出现两大困难:一是顾客的服务时间分布将依赖于服务台的剩余寿命;二是这种可修系统的状态会由于顾客源无限而无限。为使问题简化,现有文献都假定了服务台寿命     

平均寿命浅说

平均寿命原是人口统计中的一个术语,随着可靠性技术的诞生和发展现已广泛用于衡量产品的耐久性.然而,工程界在使用平均寿命时却存在不少误解之处,本文偿试把这个概念说清楚. 要说清平均寿命,首先要知道什么是寿命.产品的寿命是指产品从完好状态开始到刚进入失效状态为止所经历的一段时间.定义中涉及的产品完好状态和失效状态工程上必须确切描述,换句话说,在研究产品的耐久性时,首先应严格定义产品完好状态的开始时刻和产品失效状态的精确判据. 对不可修复的产品,通常以产品开始使用时刻作为产品完好状态的起点.对可修复的产品,如果能保证“…     

计算可修系统在(0,t]中平均故障次数的新方法

§1.引言 设系统S由n个部件(或称单元)组成,记为S={e_1,…,e_n}。假定在任一时刻t,系统S不是完好(工作)就是故障(修理)。然而,这时部件e_i却可能处于工作、贮备、修理、待修等诸种情况之一。 定义1 全部e_i所可能处的各种确定情况的组合称为系统的状态。 显然,系统S的状态有限,经适当编号后可记为     

机助故障树分析的统一算法

本文提出一种机助故障树分析的统一算法。该算法能给出原故障树的全部模块子树,各模块子树及其对偶模块子村的不交蕴涵族,原故障树的质蕴涵族,完成常规的定量计算和某些新的定量分析。它与Willie的算法相比较功能更全也更为有效。     

Co-evolution of the brand effect and competitiveness in evolving networks

The principle that ‘the brand effect is attractive’ underlies the preferential attachment. Here we show that the brand effect is just one dimension of attractiveness. Another dimension is competitiveness. We firstly introduce a general framework that allows us to investigate the competitive aspect of real networks, instead of simply preferring popular nodes. Our model accurately describes the evolution of social and technological networks. The phenomenon that more competitive nodes become richer can help us to understand the evolution of many competitive systems in nature and society. In general,the paper provides an explicit analytical expression of degree distributions of the network. In particular, the model yields a nontrivial time evolution of nodes’ properties and the scale-free behavior with exponents depending on the microscopic parameters characterizing the competition rules. Secondly, through theoretical analyses and numerical simulations, we reveal that our model has not only the universality for the homogeneous weighted network, but also the character for the heterogeneous weighted network. Thirdly, we also develop a model based on the profit-driven mechanism. It can better describe the observed phenomenon in enterprise cooperation networks. We show that the standard preferential attachment,the growing random graph, the initial attractiveness model, the fitness model, and weighted networks can all be seen as degenerate cases of our model.     

欧洲航空超网络的实证分析

本文将机场定义为节点,将航空公司定义为超边,采用超网络方法分析了欧洲航空网络的特征.实证结果表明,这些统计属性的累计概率分布服从指数分布,说明多个随机因素的相互作用导致了该超网络的形成,较小的平均距离和较大的聚集系数表明该超网络符合小世界效应.