Design of 4-disjoint gamma interconnection network layouts and reliability analysis of gamma interconnection Networks

Multistage interconnection networks (MINs) are widely used for reliable data communication in a tightly coupled large-scale multiprocessor system. High reliability of MINs can be achieved using fault tolerance techniques. The fault tolerance is generally achieved by disjoint paths available through multiple connectivity options. The gamma interconnection network (GIN) is a class of fault tolerant MINs providing alternate paths for source–destination node pairs. Various 2-disjoint and 3-disjoint GIN architectures have been presented in the literature. In this paper, two new designs of 4-disjoint paths multistage interconnection networks, called 4-disjoint gamma interconnection networks (4DGIN-1 and 4DGIN-2) are proposed. The proposed 4DGINs provide four disjoint paths for each source–destination pair and can tolerate three switches/link failures in intermediate interconnection layers. Proposed designs are highly reliable GIN with higher fault-tolerant capability than other gamma networks at low cost. Terminal pair reliabilities of proposed designs and various other 2-disjoint and 3-disjoint GINs are evaluated, analyzed and compared. Reliability values of proposed designs are found higher.     

Multicriterion network optimization problem

In this paper a multicriterion network optimization problem is discussed. The problem formulation is given and next the min-max principle of optimality is used in order to define the optimal path in the network. Then a method for seeking the optimal path in the network is described.     

一种新型混合互连网络拓扑结构的分析与优化

随着高性能互连网络规模的增大,如何通过互连网络拓扑结构的设计来提升系统的性能和降低物理开销成为了系统设计的关键之一。传统的拓扑结构(可分为直接网络和间接网络)在网络规模增加时,不能很好地折衷网络性能和物理开销的关系。2012年Roberto P等人提出一种新型混合的拓扑结构,结合了直接网络和间接网络的特点,有效考虑了物理开销和网络性能的折衷。在此基础上,将新型混合拓扑每一维上的唯一的一个间接网络优化为多个间接网络,经过理论分析和实验模拟新型混合拓扑结构优化后的混合拓扑结构以及较常用的传统拓扑结构,优化后的混合拓扑结构能够在提升网络性能的同时降低物理开销。     

动态视角下的城市道路交通网络失效评价模型

利用可靠性相关理论,在对交通网络状态变化规律分析的基础上,给出了了城市道路交通单元及交通网络的‘失效—非失效’态的表达方法;分析了路段单元及交通网络的状态从观察起始点t0到首次演变到‘失效态’的时间分布规律,并以此为基础推导了城市道路单元及交通网络的失效概率、平均失效时长、失效率以及条件失效时长等失效评价模型,给出了模型标定的方法。以国内某城市核心城区5条道路单元组成的路网为实例,对首次失效时间进行了分布拟合及检验,对模型进行了标定,并将模型计算结果与实际观察结果进行了对比。结果表明,利用对数正态分布来拟合首次失效时间较为理想,而且模型的计算结果与实际观察结果也非常接近,表明模型具有良好的实用性。     

基于可信计算的网络互联模型

针对传统互联技术难以实现内外网在安全可信情况下互联互通互操作的问题,将可信计算中的相关技术应用到网络互联中,实现内外网在安全隔离情况下的信息交互。研究了网络可信互联框架模型,结合该模型,对基于身份的公钥认证算法进行改进,设计了认证系统与接入者之间的密码协议。分析实体的持续性行为进行并建立评估树模型,对接入者自身的安全状况进行综合可信度评估。最后,通过测试实验对评估方法进行分析与验证,实验结果表明,该评估模型排除时效偏差等不利因素的影响,具有可行性和有效性。     

Computer network reliability optimization under double-resource assignments subject to a transmission budget

This paper discusses a double-resource assignment problem to maximize network reliability for a computer network. The resources are separated into two types: one is transmission line and another is transmission facility. In particular, each resource is multistate due to full failure, partial failure, or maintenance. Such a network assigned with multistate resources is usually modeled as a stochastic-flow network. Furthermore, each resource should have a transmission cost in reality. Hence, the network reliability is the probability that a specified demand is transmitted through the network successfully subject to a transmission budget. This paper devotes to find out the optimal double-resource assignment with maximal network reliability. An optimization algorithm combining the genetic algorithm, the minimal paths, and the Recursive Sum of Disjoint Products is developed to solve the proposed problem. The experimental results show that the proposed algorithm can be executed in a reasonable time.     

二部图最大匹配问题的分层网络优化模型

为解决二部图最大匹配问题,提出了分层网络及网络逆序的概念,在此基础上建立了一种分层网络优化模型及其算法。给出了算法的思想、步骤、实例、时间复杂度分析,概述了求解二部图最大匹配问题的常见算法,与分层网络优化算法进行比较。实验验证,算法可读性强,易于理解和操作,在解决大规模二部图最大匹配问题时具有良好的性能。     

蚁群算法在冗余系统可靠性最优分配上的应用

针对各种进化算法所存在的早熟收敛,易陷人局部极值点的缺点,采用两种不同的状态转移规则和与系统属性紧密相关的信息素更新规则,用蚁群算法解决元件可选择不同类型的最优冗余分配问题,实例仿真结果表明蚁群算法可以在相对短的时间内较快的找到问题的最优解。     

Design and reliability analysis of fault-tolerant shuffle exchange gamma logical neighborhood interconnection network

The Journal of Supercomputing - Multistage interconnection networks are used as a medium for interconnecting processors and memories in multiprocessor systems. Multistage interconnection networks...     

面向级联失效的加权网络负载容量非线性模型鲁棒性优化

在考虑网络负载容量关系的情况下,研究加权网络中的级联失效现象。提出了负载容量非线性模型,并针对模型参数的多目标优化问题,通过理论分析确定其影响因素。以级联失效前后网络连通性测度的比值作为鲁棒性测度,以网络容量与负载的比值平均数作为网络成本测度,采用基于拥挤距离排序的多目标粒子群优化算法(MOPSO-CD)对参数进行优化。最后通过在模拟网络和实际网络中进行的仿真比较,验证了优化后的负载容量非线性模型可以在有限的网络成本下更好地提高网络对级联失效的抵御能力。     

改进神经网络模型对通信网可靠性的预测

首先利用一种改进后的粒子群算法对BP神经网络权值的选取进行优化,然后以LAN/WLAN集成网络为背景,用三种方法（BP神经网络、改进PSO算法优化后的BP神经网络、SVM）建立了LAN/WLAN集成网络可靠性的预测模型,最后通过实验比较,证明了改进后的神经网络模型预测通信网的可靠性、有效性和优越性。     

Topology optimization of interconnection networks

This paper describes an automatic optimization tool that searches a family of network topologies to select the topology that best achieves a specified set of design goals while satisfying specified packaging constraints. Our tool uses a model of signaling technology that relates bandwidth, cost and distance of links. This model captures the distance-dependent bandwidth of modern high-speed electrical links and the cost differential between electrical and optical links. Using our optimization tool, we explore the design space of hybrid Clos-torus (C-T) networks. For a representative set of packaging constraints we determine the optimal hybrid C-T topology to minimize cost and the optimal C-T topology to minimize latency for various packet lengths. We then use the tool to measure the sensitivity of the optimal topology to several important packaging constraints such as pin count and critical distance.     

低碳环境下闭环供应链网络设计多目标鲁棒模糊优化问题

针对低碳环境下多级闭环供应链网络设计的战略定位和配置问题,综合考虑网络参数的模糊性以及多产品流,以供应链网络的总成本和总碳排放最小为目标,建立多目标鲁棒模糊优化模型.该模型将机会约束的最低置信水平作为决策变量,实现目标函数期望值、最优鲁棒性和可行鲁棒性之间的有效平衡.最后,设计一种基于必要性测度的交互式$\varepsilon$约束模糊求解方法,并通过算例验证所提模型和算法的有效性和可行性.     

Analytical model based on green criteria for optical backbone network interconnection

Key terms such as Global warming, Green House Gas emissions, or Energy efficiency are currently on the scope of scientific research. Regarding telecommunications networks, wireless applications, routing protocols, etc. are being designed following this new “Green” trend. This work contributes to the evaluation of the environmental impact of networks from physical interconnection point of view. Networks deployment, usage, and disposal are analyzed as contributing elements to ICT's (Information and Communications Technology) CO₂ emissions. This paper presents an analytical model for evaluating and quantifying the CO₂ emissions of optical backbone networks during their lifetime. The main goal of this work is to present the model and illustrate how to evaluate the physical interconnection of backbones from an environmental perspective. This model can be applied as a new type of decision support criteria for backbone's interconnection, since minimization of CO₂ emissions is becoming an important factor. In addition, two case studies are presented to illustrate the use and application of this model, and the need for de facto and international standards to reduce CO₂ emissions through good network planning.     

Uniform load sharing on a hierarchical content delivery network interconnection model

Content management system (CMS) is an infrastructure for efficient distribution, organization, and delivery of digital content. It is desirable that the content must be successfully delivered regardless of the end users location or attachment network. For the end to end delivery of content, a virtual open content delivery infrastructure is formed by interconnecting several CDNs. In this paper, we focus on content delivery network interconnection. An efficient and suitable to implement hierarchical CDNI architecture, named as HCDNI, is proposed to reduce the limitations of CDNIs. Next, a content distribution and redistribution scheme is proposed so that the searching time and the round trip time for the content delivery can be minimized. Next, we find a reliable and fault tolerant scheme for web server replica placement and content caching. Finally, analysis and simulation studies show that proposed algorithm results in a significant improvement in terms of data routing, path selection, content distribution and redistribution, load balancing and network scalability.     

基于可靠度的计算机系统优化问题的研究

分析了计算机系统硬件优化配置问题,给出了该问题的优化模型,并利用模拟退火算法和遗传退火算法对求解该问题进行了具体设计。通过实例仿真比较,遗传退火算法能得到比文献中算法和模拟退火算法更好的结果,表明算法是非常有效的。     

一种自相似网络可靠性分析模型

利用ON/OFF模型产生自相似流量,提出了一种基于排队延迟的自相似网络可靠性分析模型。将节点和到达信息流视为G/M/1/B排队模型,利用大偏差理论得到节点平均排队延迟时间,进而得到网络各种工作状态下全网平均排队延迟时间。再利用延迟阀值得到各种工作状态下的网络可靠性,进一步得到全网可靠性。通过模拟计算,得到了给定拓扑结构网络的可靠性与自相似程度、ON/OFF源数量以及节点缓存大小之间的关系。     

考虑双重不确定性的公交时刻表分布鲁棒优化模型

城市公交系统由于受外界干扰,其需求和运行环境在时空上呈现高度不确定性,给日常运营组织带来了巨大挑战.为增强公交系统对于客流需求和运行场景双重不确定性的应对能力,提出一种权衡服务质量和服务鲁棒性的单一线路时刻表优化方法.方法采用离散场景集刻画需求的不确定性,并以滞留人数的期望值和条件风险值最小化为目标,综合考虑多方面约束,构建多场景耦合的分布鲁棒优化模型(DRO).为方便模型求解,运用模糊集描述场景发生概率的不确定性,再借助对偶理论和常规线性化方法将原模型转化为等价的混合整数线性规划形式.最后通过实际案例对方法进行分析,结果表明:等价转换得到的线性形式可由GUROBI优化软件快速求得最优解; DRO模型所得时刻表能有效应对双重不确定性;随着不确定性的上升,分布鲁棒优化方法相较于传统随机规划方法体现出更强的鲁棒性,可以切实改善公交系统运营的稳定性.     

Topological optimization models for communication network with multiple reliability goals

Network reliability models for determining optimal network topology have been presented and solved by many researchers. This paper presents some new types of topological optimization model for communication network with multiple reliability goals. A stochastic simulation-based genetic algorithm is also designed for solving the proposed models. Some numerical examples are finally presented to illustrate the effectiveness of the algorithm.     

变路网情况下多库房应急物资调度模型及算法

考虑一类大规模自然灾害应急救援情景,基于实际应用条件和需要,建立了最优变路网情况下多库房应急物资调度模型。探讨了车辆所依托的路网结构可变和多库房对调度算法的双重影响,设计了一种求解问题的动态加速自适应遗传算法。作为结论的直接应用,给出的仿真算例验证了问题模型及其求解算法的合理性和有效性。