静态环型波长路由光网络中RWA问题的研究

RWA问题是静态环型波长路由光网络中的一个核心问题.随着RWA优化算法求解方式的简化,算法的运算效率得到了提高,但却牺牲了解的优化性能.如何使优化效率和时间效率协调统一是当前环网波长路由光网络中RWA优化算法设计的难点.本文对静态波长路由光网络中RWA问题进行了阐述,综述了当前国内外的RWA算法,并对静态环网中几种新的算法进行了分析研究.     

波长路由光网络中RWA算法的设计分析

文章通过对波长路由光网络中路由与波长分配(RWA)问题的研究,介绍了求解路由子问题和波长分配子问题的常用方法,总结了3种类型的RWA问题的优化解决方法,最后对目前RWA算法设计中存在的问题进行了分析并阐述了解决此类问题的重要性.     

波分复用全光网络路由和波长分配算法

本文根据波分复用全光网络路由和波长分配（ＲＷＡ）实现过程的不同把算法划分为两大类;路由和波长分配分解法和路由和波长分配并行法。对这两类分别讨论了动态和静态ＲＷＡ算法。     

DNA计算在整数规划问题中的应用

基于生化反应原理的DNA计算由于在解决一类困难问题,特别是NP-完全问题上具有硅计算机无法比拟的优势,因此对DNA计算的研究具有重要意义。利用在基于表面的DNA计算中采用荧光标记的策略,提出了一种基于DNA计算的一类特殊整数规划问题最优解的求解算法,新算法利用荧光猝灭技术,通过观察DNA分子表面的荧光来排除非解。算法分析表明,新提出的基于DNA计算的求解算法具有编码简单和错误率低等特点。     

Multicast wavelength assignment with sparse wavelength converters to maximize the network capacity using ILP formulation in WDM mesh networks

In general, multicast routing and wavelength assignment (MC-RWA) can be subdivided in routing and wavelength assignment issues in wavelength-division multiplexing (WDM) mesh networks. Previous studies on WDM multicast have mainly focused on WDM multicast routing. The multicast wavelength assignment problem is studied in this paper. A unicast routing path can be established by a lightpath in an all-optical network. However, in the multicasting case, a multicast routing tree can be established by a single light-tree or several lightpaths, or a combination of several light-trees and lightpaths. We propose a wavelength assignment algorithm for finding an optimal combination of lightpaths and light-trees to construct a newly required multicast session. First of all, two cost functions are given to evaluate the establishing cost for each feasible wavelength, and then find a set of wavelengths that covers all destinations with the minimal cost using Integer Linear Programming (ILP) formulation. We focus on maximizing the total number of users served in a multicast session and the network capacity. The simulation results show that the proposed algorithm can improve system resource utilization and reduce the blocking probability compared with the First-Fit algorithm.This research was partially supported by the Grant of National Science Council, R.O.C. (NSC 94-2745-E-155-007-URD).     

一种提高光网络攻击容忍性的RWA算法研究

通过研究光网络中带内串扰攻击及其传播原理,在基于串扰攻击有限传播的模型之上,提出了一种限制串扰攻击传播的波长路由分配(Routing and Wavelength Assignment,RWA)算法.该算法把分配后能产生最小串扰攻击传播最大值(Crosstalk Attack Propagation Maximum,CAPM)的波长路由分配给新的光路请求,从而减少全网的潜在的攻击传播范围.仿真结果显示,与常用的首次命中(Fist-fit)RWA算法相比,该算法能显著降低全网的串扰攻击传播最大值,从而提高光网络的攻击容忍性.     

解无约束极大极小问题的非对称神经网络算法

本文构造了一种新的非对称神经网络模型，用于求解极大极小无约束优化问题，并证明了非对称线性神经网络和非线性神经网络是整体Ｌｙａｐｕｎｏｖ稳定的，且收敛于对应的Ｌａｇｒａｎｇｅ方程的稳定点，计算机模拟的结果表明此方法是可行的，且具有良好的整体收敛性。     

Practical Integrated Design Strategies for Opaque and All-Optical DWDM Networks: Optimization Models and Solution Procedures

Dense wavelength division multiplexing (DWDM) opaque networks use expensive optical/electrical/optical (O/E/O) conversion at each end of a fiber link. Several technological advances have been used in an attempt to reduce the O/E/O conversion cost component: improved optical amplifiers using distributed Raman amplification allow signals to traverse longer distances without amplification and/or regeneration; optical switches allow the signal to remain in the optical domain most of the time. Networks that use this equipment to eliminate some of the O/E/O conversions are called transparent or all-optical networks and benefit from reduced capital costs at the expense of operational costs and complexity in order to handle potential adjustments in traffic demand. In this investigation, we develop optimization-based algorithms for DWDM network design and traffic routing for both opaque and all-optical networks. This study compares the performance of AMPL/CPLEX implementations of both algorithms on realistically sized networks with up to 36 nodes and 67 links. In all test cases considered the all-optical network design is substantially less expensive than the traditional opaque network design with cost reductions in the range of 12% to 26%.     

Reducing the lightpath establishing time of FWM-aware dynamic RWA for wavelength-routed optical networks

A dynamic routing and wavelength allocation technique with an interplay between physical and network layer parameters encompassing Four-wave mixing (FWM) awareness and teletraffic performance of wavelength-routed optical networks has previously been proposed for a distributed approach. In this article, we present a fast computational algorithm for our routing and wavelength assignment (RWA) encompassing FWM-induced crosstalk. The objective is to minimize the time of establishing a dynamic lightpath. For this purpose, a precomputed matrix of FWM crosstalk products is used in an adapted version of the FWM-aware dynamic RWA algorithm. The approach is validated through simulations showing improvement up to 30–50% on the provisioning time of lightpaths for different network topologies compared to an online full computational scheme.

HFC双向网络改造中存在的问题及处理办法

随着国家对"三网融合"的要求以及居民对电视节目多样性的需求,原有HFC网络迫切需要改造,在改造过程中,我们需要选择适合本网络的模式,同时,结合本市网络改造,提出可能出现的问题并提出处理办法。     

Comparison of potential- and activation-based formulations for the inverse problem of electrocardiology

Two predominant source formulations for the inverse problem of electrocardiology currently exist. They involve the reconstruction of epicardial potentials or myocardial activation times from noninvasively recorded torso surface potentials. Each of these formulations have their advantages, however, they have not been systematically compared against each other. We present results from a simulation study which compared a number of epicardial potential (Tikhonov, Truncated singular value decomposition (TSVD), Greensite-Tikhonov and Greensite-TSVD), and a myocardial activation time formulation for the inverse problem of electrocardiology. A number of different methods were also used to determine the appropriate level of regularization (optimal, L-curve, zero-crossing, and composite residual and smoothing operator) to apply to each formulation. The simulation study was conducted using an anatomically based boundary element porcine model with a variety of cardiac sources. Varying levels of geometric error were introduced to the system and solutions were computed using each of the inverse algorithms. Results show that under pure Gaussian noise potential-based methods performed best at low noise levels while the activation-based method was less effected by higher noise levels. In the presence of correlated geometric error, the activation-based method out performed the potential methods, with the Greensite-Tikhonov method being the most favored potential-based method when using the L-curve or zero-crossing method to determine the regularization parameter.     

多播光网络研究中几个问题的探讨

波分复用(WDM)技术的开发和应用使得网络中的信息容量得到了极大的提高，而网络中业务信息的多样化则促进了多播技术的应用和发展。多播的出现使网络的节点结构、虚拟拓扑连接方式及路由和流量疏导算法变得更加复杂多样。为此对光网络中各种多播方式及节点结构并对现有的路由和波长分配算法进行了评述。在此基础上提出了对这类光网络中的信息流量进行疏导时应遵循的几个基本原则，目的是提高波长容量的利用率，减少网络中所用的波长和分插复用器（ADM）数，降低网络的成本和费用。     

基于精英蚂蚁算法的动态路由和波长分配研究

为了更有效地解决密集波分复用光网络中动态路由和波长分配问题,提高光网络中资源利用率,该文提出了一种基于精英策略蚂蚁系统算法的动态路由和波长分配问题的解决方法。在仿真中通过将精英策略蚂蚁算法应用到经典的美国国家科学基金会网络中,动态地完成路由和波长的分配。仿真结果表明,精英策略蚂蚁算法能够降低网络阻塞率,有效提高密集波分复用光网络的带宽资源利用率,并且随着波长数目或者网络负载的不断增加,这种优势更加明显。     

虚拟网络功能资源容量自适应调整方法

为了实现网络功能虚拟化平台中物理资源的动态按需分配,该文提出一种虚拟网络功能资源容量自适应调整方法.该方法首先利用长短期记忆网络预测平台流量的变化趋势,然后结合流量预测结果设计了一种基于多层前馈神经网络的虚拟网络功能资源需求预测方法,最后根据资源需求预测结果,设计了一种基于动态编码遗传算法的虚拟网络功能动态部署方法,实...     

NETWORK ANALYSIS OF EIGENVALUE PROBLEM FOR MULTILAYER DIELECTRIC WAVEGUIDE CONSISTING OF ARBITRARY NUMBER OF LAYERS

In this paper,the eigenvalue problem of a multilayer dielectric waveguide consisting of arbitrarynumber of layers is solved by the microwave network method.A general program with the function of com-puter graphics has been developed for analyzing the dispersion characteristics and the electromagnetic fielddistributions of an N layer dielectric waveguide.As an example of practical applications,the procedure ofmode conversion and mode separation in dielectric branching waveguides is vividly demonstrated throughanalyzing the field distributions of asymmetric multilayer dielectric structures and the general rules of modeconversion are discussed.     

基于路径的整数线性规划方法在阻塞IP over WDM网络中能耗优化的应用

针对容量有限的透明IP over WDM网络模型,该文提出一种基于路径的整数线性规划(ILP)方法来优化网络的能耗。相对基于连接的整数线性规划方法,该方法可以在光层提供更多的路径选择组合。仿真结果显示,基于路径的整数线性规划方法能够通过选择更优的光路组合进一步降低网络的能耗。     

脑电计算问题应用平台的设计与实现

脑电正及脑电逆问题的研究一直是脑电研究领域的核心。文中针对脑电计算问题进行了算法研究和软件系统设计开发。首先对已有的脑电计算方法进行研究分析,选出适宜的计算方法嵌入到软件系统中;基于Visual C++6.0平台,设计开发了系统软件,脑电正系统可以以灰度图形式直观显示出脑电压大小的分布情况,脑电逆系统可由获取的脑电数据快速地计算出偶极子电偶极矩的大小并实时显示。该系统具有界面友好、操作简单、易于扩展等特点。     

Analyzing the redeployment problem of mobile wireless sensor networks via geographic models

Since sensor networks integrate virtual and physical worlds, spatial deployment of sensor nodes may have a significant impact on operation costs and performance. This paper investigates the problem of redeploying mobile sensor networks, in which the objective is to design an efficient algorithm which optimizes the global performance of networks. We take a novel approach in analyzing the problem from a macroscopic perspective, modeling the sensor deployment as a density distribution and the redeployment algorithm as an integral transform of that distribution. Despite lacking the details for individual node, we may still derive insightful results, such as number of moves, stability, and transitional behavior. We also derive the bound of total moving distance difference between an arbitrary one‐move algorithm and the optimum redeployment algorithm, allowing for the estimation of the minimum moving distance from the initial deployment region. In summary, we present an theoretical analysis of the redeployment problem from a macroscopic perspective, and believe the results can serve as a basis for further algorithm development and analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

一种基于神经网络模型的计算机通信网络迟延和流量分配新算法

求解计算机网络最小平均迟延和流量分配的本质是一个联合优化问题。进一步分析得出，它可近似为一个二次型优化问题。利用一种具有全局收敛性质的神经网络模型来解决这个问题，计算结果表明这种方法是可行且有效的。