分布式光网络中的波长和端口数目优化分析

研究了分布式Mesh光网络中动态业务疏导问题中的波长和端口优化问题,通过对分布式Mesh光网络中不同业务和网络拓扑情况下的网络结点波长和端口使用数目的仿真分析,得出网络中的合理波长和端口数目配置,为网络规划和设计提供依据.     

波长扫描法布里-珀罗干涉仪的优化设计

分析了可用于绝对距离测量的波长扫描法布里－珀罗干涉仪腔内多光束干涉对输出信号的影响, 及由此产生的相位测量误差。研究表明, 通过选择合适的腔端面反射率和参考腔长度可以减小相位测量误差。优化选择的腔面反射率为０．１０～０．１５, 参考腔长为０．９５ ｍ ｍ , 在１ ｍ ｍ 范围内系统可达到０．０５ μｍ 的测距精度。     

Wavelength Conversion in WDM All-Optical Networks and Analytical Models

This paper gives a brief introduction to the various wavelength conversion techniques. In order to explain the applications and benefits of the wavelength conversion techniques in WDM all-optical networks, several analytical models are studied.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Reducing Power Consumption in Core Wavelength Division Multiplexing Optical Networks

Abstract

This work proposes some heuristic criteria aiming at saving energy by efficiently switching off optical fibers in generalized multi-protocol label switching-controlled optical networks during low traffic load periods and by taking into account network equipment power consumption. Simulations show that up to 80% of energy can be saved when the traffic is reduced by 20% with respect to its maximum. The impact of network design parameters is also investigated.     

多波长双向抽运光纤拉曼放大器的优化设计

通过合理分析提出了便于计算多波长双向抽运光纤拉曼放大器信号及噪声功率的实用数值模型,给出求解信号和噪声功率的快速算法。在定义抽运方向度为前向抽运功率与总抽运功率值的比值后,通过对计算结果的分析发现信道平均放大自发辐射噪声功率随着抽运方向度的提高而单调递减;而信道平均双重瑞利散射噪声功率相对抽运方向度的变化曲线始终成U字形。不同的增益下存在对应的最优抽运方向度,在此抽运方向度下放大器总噪声最低。进而考虑在信号非线性失真的条件下提出了抽运方向度优化的衡量指标。优化后的多波长双向抽运方式不仅能保证对所有信道的平坦放大,而且其综合性能明显高于后向抽运方式。     

基于SiPLS-SPA波长优选的血红蛋白定量分析研究

血红蛋白是人体的一项重要生理指标,浓度异常会导致人体产生各种疾病。红外光谱技术具有简单、无损、快速等优点,非常适合用于生理参数的定量分析。由于光谱背景复杂、有效信息弱,如何提取有效特征变量,构建精准定量模型是个难题。针对此问题,以血液样本和血红蛋白仿体溶液样本光谱数据为研究对象,采用SPXY法、 K＿S法、 duplex法、等间隔划分法四种数据集划分方法划分数据并通过建模对比,优选出最佳数据集划分方法为SPXY法。遍历了SavitzkyGolay一阶求导滤波(S＿G1)+小波变换、小波变换+S＿G1、标准正态变量变换(SNV)+S＿G1三种预处理方法,优选出SNV+S＿G1预处理方法。结合串联思想,提出组合区间偏最小二乘法(SiPLS)与连续投影算法(SPA)串联的特征波长优选方法,构建SiPLS-SPA-PLS预测模型,用两组数据对模型进行验证,依据评价指标判断模型的优劣,并与全谱PLS, SPA-PLS和SiPLS三种定量模型相比较。实验结果表明：(1)使用SiPLS-SPA-PLS模型进行定量分析,血液样本的R_c,R_p, RMSEC和R...     

Nature-Inspired Routing and Wavelength Assignment Algorithms for Optical Circuit-Switched Polymorphic Networks

Polymorphic optical networks simultaneously support several optical switching paradigms over a single physical network. In this way, they provide service differentiation at the optical layer by employing the most appropriate paradigm for each service. One type of such architecture is the optical circuit-switched polymorphic network (OCSPN), which combines optical circuit switching paradigms with different grades of dynamism. The performance of this network relies on the utilization of efficient routing and wavelength assignment (RWA) algorithms. In this article, we review the fundamentals of OCSPNs and present a set of efficient RWA algorithms based on ant colony optimization and genetic algorithms.     

串扰对密集波分复用网络扩展性的影响

串扰是限制密集波分复用网络扩展的一个重要因素。理论分析了三种典型光交叉连接中的串扰。结果表明基于扩展贝奈斯光交换结构的光交叉连接可以完全消除低于二阶的各类串扰,同时,若将可调谐的窄带滤波器引入到结构2中可以消除低于三阶的各类串扰。用数值模拟的方法分析了带内串扰对强度调制直接检测网络扩展性的影响。结果表明,基于扩展贝奈斯光交换结构的光交叉连接对器件串扰系数的要求得到了很大的放宽,用它来组建的密集波分复用网络具有很好的扩展性。串扰多是由构成光交换节点中各种器件的非理想性造成的,通过分析得出器件中产生的串扰可以从系统中得到很好的解决。     

考虑非线性效应的路由与波长分配算法

本文研究了在波长路由的智能光网络中选择路由与波长分配(RWA)过程中如何考虑非线性效应的影响.在简要分析了考虑非线性效应影响的必要性后,以交叉相位调制为例推导出了一种简单的计算非线性效应引起的光功率代价计算公式,并讨论了如何将其引入路由与波长分配算法中.仿真结果表明非线性效应确实对RWA的优化结果产生一定的影响,其程度与物理拓扑、业务需求和具体的网络传输参量有关.     

Nature-Inspired Routing and Wavelength Assignment Algorithms for Optical Circuit-Switched Polymorphic Networks

Polymorphic optical networks simultaneously support several optical switching paradigms over a single physical network. In this way, they provide service differentiation at the optical layer by employing the most appropriate paradigm for each service. One type of such architecture is the optical circuit-switched polymorphic network (OCSPN), which combines optical circuit switching paradigms with different grades of dynamism. The performance of this network relies on the utilization of efficient routing and wavelength assignment (RWA) algorithms. In this article, we review the fundamentals of OCSPNs and present a set of efficient RWA algorithms based on ant colony optimization and genetic algorithms.     

频谱分割波分复用无源光网络及色散影响

频谱分割是使用窄带光滤波器选择宽带光源光谱的一个切片的WDM技术,在波分复用无源光网络(WDM-PON)中采用波分复用器((MUX)进行频谱分割,能够实现光网络单元(ONU)的无色化.模型分析表明由于频谱分割的作用,使得波分复用器光通带外的频谱成分被过滤,减小了宽带光源的色散影响.在20 nm CWDM标准信道间隔下,能够以不超过1 dB的光功率代价支持155 Mb/s信号在20 km的G.652常规光纤上传输;在0.8 nm DWDM信道间隔下则能够支持2.5 Gb/s信号传输,色散引起的光功率代价低于0.5 dB.采用中心波长为1550 nm、谱宽70 nm、输出功率为-10 dBm的LED,研制了125 Mb/s速率信号直接调制的无色ONU.在信道间隔为20 nm、光纤长度为20 km的4波长WDM-PON系统上进行测试,色散等因素引起的光功率代价小于1 dB,系统光功率余量则超过5.6 dB.     

激光波长对煤激光诱导击穿光谱特性影响的试验研究

我国电站入炉煤种复杂多变,实时快速获取煤质成分对保障锅炉的安全、高效、低污染运行具有重大意义。将激光诱导击穿光谱(LIBS)技术应用于燃煤煤质测量,观测了不同波长激光(355,532和1 064 nm)诱导产生的等离子体时间演变特性和不同电离特性元素的谱线时间特性,对比了出现屏蔽效应时的能量阈值随激光波长的变化特征,并研究了激光波长对煤LIBS光谱特性的影响规律。结果发现：使用532 nm激光作为激发光源时,煤LIBS光谱具有最强的谱线信号强度,且出现等离子体屏蔽效应的能量阈值也较高,是一种较理想的激发光源,为LIBS技术在煤质测量领域的工业应用提供了实验依据。     

基于波段带宽的谱段测温的优化测量分析

基于窄波段内普适性的线性发射率模型,采用具有Gauss分布的传感器设计,将三波长(单色)辐射温度测量拓展到三波段(谱段)辐射温度测量,提出了使测量具有最佳温度分辨精度的优化准则。讨论优化测量的主要方式是通过改变Gauss分布的半宽度,实现从单色测量到谱段测量的逐渐递进,因而优化分析从传统的分析波长选择上,过渡到分析波段带宽的选择上。对于特定的辐射情形,依据优化准则,数值模拟结果给出了最佳温度分辨精度的波段带宽(即Gauss分布半宽度)分布。最优半宽度的分析表明,单色辐射测量往往并非是最优测量,文章的分析将给辐射优化测量提供重要的理论指导。     

Topological Properties of Fibonacci Networks

The Fibonacci numbers are the numbers defined by the linear recurrence equation,in which each subsequent number is the sum of the previous two.In this paper,we propose Fibonacci networks using Fibonacci numbers.The analytical expressions involving degree distribution,average path length and mean first passage time are obtained.This kind of networks exhibits the small-world characteristic and follows the exponential distribution.Our proposed models would provide the valuable insights into the deterministically delayed growing networks.     

Topological Properties of Fibonacci Networks

The Fibonacci numbers are the numbers defined by the linear recurrence equation, in which each subsequent number is the sum of the previous two. In this paper, we propose Fibonacci networks using Fibonacci numbers. The analytical expressions involving degree distribution, average path length and mean first passage time are obtained. This kind of networks exhibits the small-world characteristic and follows the exponential distribution. Our proposed models would provide the valuable insights into the deterministically delayed growing networks.     

智能优化算法应用于近红外光谱波长选择的比较研究

近红外光谱(NIRS)是一种间接分析技术,其应用需建立相应的校正模型。为了提高模型的解释能力、预测准确度和建模效率,需要对NIRS进行波长选择,优选最小化冗余信息。智能优化算法是以生物的行为方式或物质的运动形态为背景,经过数学抽象建立算法模型,通过迭代计算来求解组合最优化问题,其核心策略是以某种目标函数为标准,基于多元校正建模并以逐步逼近的方法筛选出有效的波长点。选用蚁群优化(ACO)、遗传优化(GA)、粒子群优化(PSO)、随机青蛙(RF)和模拟退火(SA)5种智能优化算法对烟叶总氮和烟碱近红外光谱数据进行特征波长选择,结合偏最小二乘(PLS)算法,构建了多个烟叶总氮和烟碱的校正模型,结果显示：所选用两个数据集的总氮最优模型分别为PSO-PLS和GA-PLS模型,烟碱最优模型分别为GA-PLS和SA-PLS模型,五种智能优化算法所建模型预测性能并非全部优于全谱PLS模型,但是通过智能优化算法进行波长选择后建立的PLS模型大大简化,模型的预测精度、可解释性和稳定性均有所提高。同时也对优选波长进行了解释和分析,烟叶总氮特征波长优选组合为4 587~4 878和6 700~7 200 cm-1;烟叶烟碱特征波长优选组合为4 500~4 700和5 800~6 000 cm-1,优选出来的特征波长具有实际物理意义。     

Crosstalk Elimination in Dense Wavelength Division Multiplexing Networks: Implementation and Theory

Abstract

Data traffic for multiple independent data channels can be simultaneously transmitted over a dense wavelength division multiplexing network with complete segregation. A limiting amplifier applied to each channel after the optical to electrical conversion eliminates crosstalk.     

光传送网中结合传输损伤的路由和波长分配

在波长路由光网优化设计的过程中考虑了物理传输损伤造成的限制,提出了一种联合优化思路.将光信号在传输过程中的物理损伤作为问题公式的另一维约束,给出了相应的启发式算法,并按照由粗到细的机制对所提出的思路做了相应的评估,同时对负荷平衡问题作了初步的分析.数值结果表明这种算法可以获得与优化值相近的波长需求解,并且能够保证网络的传输性能,其业务分布随着备选路径的增加而趋向均衡.     

Properties of Bottleneck on Complex Networks

The traffic bottleneck plays a key role in most of the natural and artificial network. Here we present a simply model for bottleneck dynamical characteristics consideration the reliability on the complex network by taking into account the network topology characteristics and system size. We find that there is a critical rate of flow generation below which the network traffic is free but above which traffic congestion occurs. Also, it is found that random networks have larger critical flow generating rate than scale free ones. Analytical results may be practically useful for designing networks, especially for the urban traffic network.