基于节点影响力的电力通信网拓扑结构诊断

结合电力通信网络的结构特征,建立了面向电力通信网络的复杂网络模型,从节点邻居拓扑特征和网络聚合特征出发定义了节点影响力。采用网络属性值信息熵计算网络拓扑特征及其对节点影响力的整体贡献度,从连通性和网络效率的角度分析节点故障后对网络拓扑抗毁性和鲁棒性的影响。分别针对BA网络、WS网络、地市骨干电力通信网络和省级骨干电力通信网络的节点影响力进行了仿真分析。结果显示在网络效率和连通度方面,与采用其他复杂网络指标的方法相比,所提出的方法能够更好地反映关键节点的传播影响力。     

低碳低合金钢的变幅疲劳寿命估算

分别用15MnVN钢旋转弯曲试样和经过锤击后的16Mn钢对焊接头，试验研究了带存活率的变幅疲劳寿命估算方法。结果表明，在同一应力水平下，所用试样的常幅疲劳寿命服从对数正态分布。本文首先给出了以当量应力幅表示的疲劳寿命表达式，以及带存活率的疲劳寿命表达式，并进一步给出了带存活率的变幅疲劳寿命估算方法和估算结果。最后通过变幅疲劳寿命试验结果进行了验证，表明本文的估算结果是精确的。     

Optimal elements separation in non-repairable phased-mission systems

Enhancement of the survivability of a system can be achieved by separating its elements. Since different elements can play different roles in fulfilling the system mission, the way in which they are separated strongly affects the achieved level of the mission survivability. Thus, the optimal separation problem arises. This paper formulates a new problem of optimal element separation in non-repairable phased-mission systems (PMSs) where the mission consists of multiple, consecutive and non-overlapping phases of operation. An accurate survivability analysis of a PMS must consider the statistical dependence of element states across phases as well as dynamics in system structure function and element failure behaviour. We suggest a method for finding the separation of the system elements that provides a maximal possible level of the PMS survivability while satisfying a certain separation cost constraint. A backward recursion algorithm is applied for determining the survivability of a vulnerable PMS. A genetic algorithm is used as an optimization tool in solving the newly formulated separation problem for PMSs.     

Geographic max-flow and min-cut under a circular disk failure model

Failures in fiber-optic networks may be caused by natural disasters, such as floods or earthquakes, as well as other events, such as an Electromagnetic Pulse (EMP) attack. These events occur in specific geographical locations, therefore the geography of the network determines the effect of failure events on the network’s connectivity and capacity.In this paper we consider a generalization of the min-cut and max-flow problems under a geographic failure model. Specifically, we consider the problem of finding the minimum number of failures, modeled as circular disks, to disconnect a pair of nodes and the maximum number of failure disjoint paths between pairs of nodes. This model applies to the scenario where an adversary is attacking the network multiple times with intention to reduce its connectivity. We present a polynomial time algorithm to solve the geographic min-cut problem and develop an ILP formulation, an exact algorithm, and a heuristic algorithm for the geographic max-flow problem.     

Impacts of Hierarchy in Ethernet Ring Networks on Service Resiliency

In transport networks, a multi‐ring architecture is very useful to facilitate network planning and to design and provide more resilient services for customers. Unlike traditional synchronous optical network multi‐rings, the service resiliency of Ethernet‐based multi‐rings is significantly impacted by the ring hierarchy because a link or node failure in a certain level ring triggers filtering database flush actions in all higher level rings as well as in the ring with the failure, and consequently a large amount of duplicated data frames may be flooded. In this paper, we investigate how the ring hierarchy impacts the service resiliency of multi‐ring networks. Based on extensive experiments on various single‐ and multiple‐link failures, we suggest two effective inter‐ring connection rules to minimize the transient traffic and to ensure more resilient multi‐ring networks. In addition, we consider a flush optimization technique called e‐ADV, and show that the combination of e‐ADV and multi‐ring structures satisfying our inter‐ring connection rules results in a more attractive survivability performance.     

Survivable network virtualization for single facility node failure: A network flow perspective

Network virtualization facilitates the technology advancement via decoupling the traditional Internet Service Providers (ISPs) into the infrastructure provider (InP) and the service provider (SP). Revolutionary technologies hence can be easily employed by the SP and transparently mapped to the physical network managed by the InP after resolving the network embedding problem. In this work, we target on importing resilience to the virtualization context by solving the survivable network embedding (SNE) problem. We view the SNE problem from a multi-commodity network flow perspective, and present an Integer Linear Programming (ILP) model for both splittable and non-splittable flow to achieve joint optimal allocation for the working and backup resources. For large-scale problems, we propose two efficient heuristic algorithms for the case with splittable and non-splittable flow, respectively. Our performance evaluation shows that the splittable mapping outperforms the non-splittable mapping in terms of the consumed resources, while the latter bears the advantage of consistent QoS guarantee.     

The Integrated Control-Mechanism in ATM-Based Networks

Survivability is one of the important issues in ATM-based networks since even a single network element failure may cause a serious data loss. This paper introduces a new restoration mechanism based on multi-layer ATM survivable network management architecture. This mechanism integrates the general control and restoration control by establishing the Working VPs logical network, Backup VPs logical network and spare logical network in order to optimally utilize the network resources while maintaining the restoration requirements.     

改进证据模型下的防空武器系统生存能力评估

为了评估防空武器系统在作战背景下的生存能力,引入证据推理方法以综合多个不同类型专家的意见;通过证据加权平均法解决了证据高度冲突问题,改进了基本证据理论的证据模型.提出利用改进的证据模型进行防空武器系统生存能力评估的方法,并应用该方法对防空武器系统在作战背景下的生存能力进行实例分析.     

基于ADC的信息系统生存能力评价

立足于任务这个高层次的用户需求，结合对象、任务、条件、时间和能力这5个方面的内容，通过对可用度A、可信赖度D和能力C的分析，提出了基于ADC评估方法的信息系统生存能力评价模型．实例分析表明，该模型有效地结合了用户的实际需求，并且能够根据系统生存能力的评判结果给出相应的改进建议，以便能在有限的资源下尽可能提高信息系统的生存性，在恶意环境下顺利完成任务．     

Circular and radial design comparison of survivability in asymmetrical hierarchical networks

Communication networks are immensely important today, since both companies and individuals use numerous services that rely on them. This paper considers the design of hierarchical (communication) networks. We consider the survivability of asymmetrical hierarchical network flows (AHNF), when arcs failure and, hence, flow destruction is probable. In such networks, it is supposed that the remaining arc capacities are known and the guaranteed evaluation of the functional capability assumes finding the worst distribution of flow in the destructed network. Since, in the network flows, a unique efficiency criterion is not generally known or defined, we assess the quality of the network functioning by a measure of demands satisfaction, i.e. the fraction of satisfied demands at the sink nodes. With regard to this criterion, we construct the mathematical model of the network regardless of the design structure. Then, by defining a measure of satisfying the demands, we compute and compare the survivability of two well-known reserve designs, namely radial and circular reserves.