基于QoS协同关联的改进Skyline制造服务组合优化方法

服务社会网络环境下,云制造服务通过与其他参与同一任务的服务共享与竞争物理设备、信息、知识等资源形成协同效应,对双方实际执行效果具有重要影响,导致出现QoS偏离现象,现有服务选择模型难以适应这一情景。根据服务协同网络特点,本文提出基于QoS协同关联的制造服务组合方法。运用QoS协同关联和协同系数表达资源共享、冲突对QoS的影响程度,构建了新的服务选择优化模型。基于创新Skyline服务对概念,改善了Skyline算法在QoS协同关联条件下的搜索效率和结果,通过智能汽车制造仿真实验,验证了本文模型和算法的有效性。     

环形全光WDM网络的波长分配

我们考虑的问题来自于基于波分复用技术(WDM)的全光环形网络．给定环形网络中一个路(通讯请求)的集合，将每一条路分配一个波长，使得经过相同连接的路必须分配不同的波长我们的目标就是找一个波长分配方案使所需的波长数目最小．令ω表示为路集中最大两两相交路的个数．本文我们设计了一个可以保证指派到路集的波长数目不超过1．5ω的近似算法．因为ω是路集所需波长最小数目的一个下界，所以该算法的近似比不超过1．5．     

求解网络最大流问题的一个算法

为了便于建立与网络最大流问题有关的决策支持系统，本给出一个求解网络最大流问题的数值算法。证明了算法的理论依据，并举例说明了算法的应用。该算法能求出网络最大流和最小截，并具有易于编程实现、收敛性好等优点，大量数值实验表明该算法非常实用有效。     

满足路径约束的最优路算法

满足路径约束的最优路问题已被证明是NP-hard问题。本针对源点到宿点满足两个QoS(服务质量)度量的路由问题，给出一种保证时延的最小费用路由启发式算法。这个算法的优点是计算较简单、占用内存小、时间短。算法的复杂度是多项式的，表明算法是有效的。     

求解最大利润流问题的一个算法

为了便于建立与最大利润流问题有关的决策支持系统，本给出了一个交易网络中求最大利润流的数值算法，证明了算法的理论依据，并举例了说明算法的应用。该算法能求得问题的最优解，并具有易于编程实现、收敛性好等优点，大量数值实验表明该算法非常实用有效。     

带有模糊容量限制的网络中的最佳最小费用量大流

本文主要讨论当网络中弧容量限制和最大流目标要求带有模糊性时的最小费最大流问题，通过构造带费用的增量网络并设法寻找其中的最佳最小费用路，给出了求解这类模糊网络流问题的算法。     

运输最短时限问题的网络解法及讨论

本提出了运输最短时限问题的基于Ford-Fullerson最大流算法的网络解法，并讨论了这个算法给出的附加信息的意义和应用价值，特别是可据以解决“运输某给定量至少需费时多少”的问题。     

带有模糊容量限制的网络中的最佳最小费用最大流

本文主要讨论当网络中的弧容量限制和最大流目标要求带有模糊性时的最小费用最大流问题，通过构造带费用的增量网络并设法寻找其中的最佳最小费用路，给出了求解这类模糊网络流问题的算法。     

最大并流

本文根据运输问题中一类常见的情况建立了在并容量网络中求最大并流的网络模型，证明了最大并流问题的NP完全性，并给出了求解该问题的一种分枝定界算法．     

带有边集限制的最均匀支撑树问题

本在无向网络中，建立了带有边集限制的最均匀支撑树问题的网络模型．中首先解决最均匀支撑树问题，并给出求无向网络中最均匀支撑树的多项式时间算法；然后，给出了求无向网络中带有边集限制的最小树多项式时间算法；最后，在已解决的两个问题的基础上解决了带有边集限制的最均匀支撑树问题．     

Multi-objective OLSR for proactive routing in MANET with delay,energy, and link lifetime predictions

In this paper, we develop a multi-objective approach for proactive routing in a Mobile Ad Hoc Network (MANET). We consider three routing objectives: minimizing average end-to-end delay, maximizing network energy lifetime, and maximizing packet delivery ratio. Accordingly, we develop three routing metrics: mean queuing delay on each node, energy cost on each node, and link stability on each link. For the proposed multi-objective approach, we develop efficient prediction methods: (a) predicting queuing delay and energy consumption using double exponential smoothing, and (b) predicting residual link lifetime using a heuristic of the distributions of the link lifetimes in MANET. Extensive simulation (by using ns2) is performed for the comparison of this multi-objective OLSR with existing OLSRs. The results show that the multi-objective OLSR is effective in finding optimal routing by tradeoffs among proposed objectives.     

AD HOC网络中的区域划分和资源分配研究

建立了新的Ad Hoc无线网络的区域划分和资源分配模型,讨论了网络覆盖率和抗毁性.通过构造Voronoi图对平面单连通区域的Ad Hoc网络建立区域划分优化模型;定义了网络抗毁性的评价指标连通率,并通过构造Delaunay三角网的最小生成树和蒙特卡罗实验,取得了较好的抗毁仿真结果.最后结合K-均值分簇和罚函数法,得到了近似最优的平面复连通区域的Ad Hoc网络的区域划分和信道安排.     

Optimal multicast route packing

This paper considers the hop-constrained multicast route packing problem with a bandwidth reservation to build QoS-guaranteed multicast routing trees with a minimum installation cost. Given a set of multicast sessions, each of which has a hop limit constraint and a bandwidth requirement, the problem is to determine the set of multicast routing trees in an arc-capacitated network with the objective of minimizing the cost. For the problem, we propose a branch-and-cut-and-price algorithm, which can be viewed as a branch-and-bound method incorporating both the strong cutting plane algorithm and the column generation method. We implemented and tested the proposed algorithm on randomly generated problem instances with sizes up to 30 nodes, 570 arcs, and 10 multicast sessions. The test results show that the algorithm can obtain the optimal solution to practically sized problem instances within a reasonable time limit in most cases.     

A distributed dual ascent algorithm for the Hop-constrained Steiner Tree Problem

The Hop-constrained Steiner Tree Problem is often used to model applications of multicast routing with QoS requirements. This paper introduces a distributed heuristic for the problem based on the application of dual ascent over a graph transformation introduced by Gouveia et al. The proposed algorithm is shown to yield significantly better solutions than the previously known algorithms.     

ATM Routing Algorithms for Multimedia Traffic in Private ATM Networks

The goal of this paper is to recommend a good Private Network-to-Network Interface (PNNI) routing algorithm for private ATM networks. A good routing algorithm has to work well with multimedia traffic with several quality of service (QoS) requirements (such as cell loss ratio, cell delay and its variation etc.) in different networks under various traffic conditions. The multiplicity of QoS requirements makes the routing problem NP-complete, so our approach to the problem is based on large scale simulations involving several empirical algorithms (compliant with the PNNI routing specification) which have been tested for different network topologies and traffic scenarios. Based on analysis of tradeoffs involving performance metrics (such as blocking rate, complexity, load distribution) we recommend a consistently good routing algorithm for single domain ATM networks.     

A New Multiobjective Dynamic Routing Method for Multiservice Networks: Modelling and Performance

There are potential advantages in formulating the routing problems in modern multiservice networks as multiple objective problems. This paper presents a novel hierarchical bi-level multiobjective dynamic routing model for multiservice networks. It is based on a bi-objective shortest path algorithm, with dynamically adapted soft-constraints, to compute alternative paths for each node pair and on a heuristic to synchronously select alternative routing plans for the network in a dynamic alternative routing context. It is a routing method which periodically changes alternative paths as a function of periodic updates of certain QoS related parameters obtained from real-time measurements. The performance of the proposed routing method is compared with two reference dynamic routing methods namely RTNR and DAR by means of a discrete-event simulator.A previous short version of this work was presented at INOC’03 (International Network Optimisation Conference). Work partially supported by programme POSI of the III EC programme cosponsored by FEDER and national funds.     

基于模糊信息的多QoS约束组播路由算法研究

首次将模糊集理论应用到组播路由算法中，定义了各个QoS参数的隶属度和理想点，建立了计算各个QoS参数到理想点距离的模型和方法，将多QoS约束简化为单距离约束，设计和实现了MQMRFI算法，分析了该算法的时间复杂度和空间复杂度，仿真结果证明在CPU执行时间上优于传统的QoS组播路由算法。     

QoS-aware service evaluation and selection

Making the provision of services QoS-aware is to the advantage of both clients and providers in the e-business domain. This paper studies the problem of providers that receive multiple concurrent requests for services demonstrating different QoS properties. It introduces the “Selective Multiple Choice Knapsack Problem” that aims to identify the services, which should be delivered in order to maximise the provider’s profit, subject to maximum bandwidth constraints. This problem is solved by a proposed algorithm that has been empirically evaluated via numerous experiments.     

Flooding-limited and multi-constrained QoS multicast routing based on the genetic algorithm for MANETs

A wireless MANET is a collection of wireless mobile hosts that dynamically create a temporary network without a fixed infrastructure. The topology of the network may change unpredictably and frequently. Therefore, multicast routing in ad hoc networks is a very challenging problem. This paper proposes a multi-constrained QoS multicast routing method using the genetic algorithm. The proposal will be flooding-limited using the available resources and minimum computation time in a dynamic environment. By selecting the appropriate values for parameters such as crossover, mutation, and population size, the genetic algorithm improves and tries to optimize the routes. Simulation results indicate its better performances compared to other methods.     

Rerouting tunnels for MPLS network resource optimization

In Multi-Protocol Label Switching (MPLS) networks, traffic demands can be routed along tunnels called Label Switched Paths (LSPs). A tunnel is characterized by a path in the network and a reserved bandwidth. These tunnels can be created and deleted dynamically, depending on traffic demand arrivals or departures. After several operations of this type, the network resource utilization can be unsatisfactory, with congestion or too long routing paths for instance. One way to improve it is to reroute tunnels; the rerouting process depends on the LSP Quality of Service (QoS) requirements.