万兆以太网物理层实现的研究

在深入研究了最新高速以太网技术——万兆以太网（10GbE）的物理层实现的基础上,提出了采用四路并行的甚短距离传输（VSR）技术实现传输距离在300m以内的局域和广域万兆以太网物理介质连接子层（PMA）和物理介质相关子层（PMD）子层的方法,从而实现了万兆以太网整个物理层的功能。该方法具有构建方便、性能稳定和成本低等优点,能够满足在局域万兆以太网和较短距离上的广域万兆以太网的数据传输。     

基于波分业务端到端测试的研究

本文从波分业务端到端性能出发,提出在波分系统维护过程中,采用以太网表测试能对OTN业务链路端到端的通断、性能进行完整的测试。通过采用城域波分/OTN的业务挂表测试采用远端环回,本端测试的方式,和采用两端挂表的方式测试两种方式,并论述各自优缺点,从而实现波分业务端到端完整性能测试。     

市场活动

康普高速以太网在互通测试大会上取得成功 近日，美国康普公司参加了由以太网联盟下属的高速以太网委员会举办的互通测试大会。在会上，采用美国康普的SYSTIMAX LazrSPEED 550和LazrSPEED 300光缆布线的基础设施超出了电气电子工程师协会关于高速以太网性能的8023ba标准的要求，并成功地展示出与其他全部供应商受测组件的互通性。     

以太网动态VLAN注册技术的研究与比较

随着网络规模的不断扩大，以太网对动态VLAN注册技术和生成树协议的要求也不断提高。目前二层以太网常用的动态VLAN注册都是基于GVRP（GARPVLAN Registration Protocol，VLAN屙陛注册协议）。但网络发生拓扑变化时，存在VLAN注册不稳定，流量临时中断等问题。本文介绍了基于MVRP（Multiple VLAN Registration Protocol，多vLAN注册协议）的动态VLAN注册原理，通过比较得出了其对GVRP作出的改进，最后结合组网实例分析了其在MSTP环境下的协议行为。     

嵌入式设备以太网接口的设计研究

针对传统嵌入式设备中以太网传输速度慢的问题,研制了一种基于FPGA和W5100的高速以太网实现方案.采用SOPC技术配置NiosⅡ处理器,控制硬件TCP/IP协议栈W5100芯片实现设备的以太网传输,并利用C2H对W5100中的关键C代码进行硬件提速.该系统传输数据可靠,传输速度较传统实现方法有显著提高,实现了系统的高速网络传输.     

Ipv4和Ipv6互通技术与双协议栈工作方式研究

我们提到的双协议栈是指在网络中的单个节点同时支持两种协议,网络中主要服务商在计算机互联网络真正全部升级到Ivp6协议之前必将支持Ipv4和Ipv6双协议栈。本文介绍了Ipv4和Ipv6双协议栈的工作机理和模型,探讨了基于双协议栈的工作方式以及互通技术。     

瑞斯康达MSAP与华为MSTP对开以太网业务时FCS的设置

FCS数据帧校验序列,采用循环冗余校验（CRC）算法,用于检测数据包在传输过程中是否损坏,为维护人员提供判断传输通道质量好坏的依据,在判断处理某些以太网传输故障过程中,借助网管系统的性能深入分析,可以迅速、准确的找出故障产生的原因,从而彻底解决故障。瑞斯康达以太网处理板8EOS—FE与华为设备以太网板互通时需要修改FCS参数的属性。     

构成新一代分布式系统的工业以太网

讨论了工业以太网构成分布式系统的可行性和优点，分析了4种满足分布式控制的工业以太网协议及其各自的优缺点。提出了设备制造商为支持这些协议在产品中增加以太网连接必须考虑的内容和实现途径。     

高性能路由器操作系统HEROS中的高可用性设计

为了保证路由器系统的整体性能和安全性，清华大学设计并实现了用于骨干网络路由器的高性能路由器操作系统HEROS（Highly Efficient Router Operation System）。骨干路由器是Internet的核心，为了保证网络的平稳运行，需要其具有相当高的可用性。本文首先分析了骨干路由器的高可用性要求，设计并实现了一种基于消息传递机的面向协议软件的高可用性系统。该系统具有对上层协议透明，独立于底层传输机制等优点，在采用主节点双机备份的硬件条件下，可以保证系统软件无故障地平稳运行。     

一种新的基于移动预测的MANET路由协议

移动自组网是一种由一系列可以自由移动的节点主机聚集而成的一个临时性动态网络。它没有固定基站，也没有作为控制管理中心的节点主机，由于其拓扑的动态性，其路由协议与其他传统网络有很大的区别。为了能更有效地移动自组网中实现数据的传送，本文提出了一种基于移动预测下的MANET路由协议，该协议综合考虑了传输路径的延时和稳定性，选择在延时限制下平均拥有最稳特性的传输路径，模拟结果表明，这种方法比基于移动预测量稳路径路由协议的传输时延要短，传送成功概率要高，而控制开销却相关不大。     

Higher‐order multi‐resolution topology optimization using the finite cell method

This article presents a detailed study on the potential and limitations of performing higher‐order multi‐resolution topology optimization with the finite cell method. To circumvent stiffness overestimation in high‐contrast topologies, a length‐scale is applied on the solution using filter methods. The relations between stiffness overestimation, the analysis system, and the applied length‐scale are examined, while a high‐resolution topology is maintained. The computational cost associated with nested topology optimization is reduced significantly compared with the use of first‐order finite elements. This reduction is caused by exploiting the decoupling of density and analysis mesh, and by condensing the higher‐order modes out of the stiffness matrix. Copyright © 2016 John Wiley & Sons, Ltd.     

Density and level set-XFEM schemes for topology optimization of 3-D structures

As the capabilities of additive manufacturing techniques increase, topology optimization provides a promising approach to design geometrically sophisticated structures. Traditional topology optimization methods aim at finding conceptual designs, but they often do not resolve sufficiently the geometry and the structural response such that the optimized designs can be directly used for manufacturing. To overcome these limitations, this paper studies the viability of the extended finite element method (XFEM) in combination with the level-set method (LSM) for topology optimization of three dimensional structures. The LSM describes the geometry by defining the nodal level set values via explicit functions of the optimization variables. The structural response is predicted by a generalized version of the XFEM. The LSM–XFEM approach is compared against results from a traditional Solid Isotropic Material with Penalization method for two-phase “solid–void” and “solid–solid” problems. The numerical results demonstrate that the LSM–XFEM approach describes crisply the geometry and predicts the structural response with acceptable accuracy even on coarse meshes.     

关于智慧家居技术的研究

针对目前国内大部分智能家居功能的局限以及实用性上的不足;如视频的远程传输,系统的远程实时控制等问题;基于人们对智慧家居系统的实际的需求,设计了一种智慧家居系统,该系统结合了以太网通信技术、WIFI网络技术、ZIGBEE通信技术等先进的技术手段,实现了数据的远程传输与控制,同时具有较大的灵活性;可以根据实际情况进行相应的裁剪和扩充。     

基于等几何裁剪分析的拓扑与形状集成优化

提出了将设计和分析、拓扑与形状优化集成的思想,探索了基于等几何裁剪分析的拓扑与形状集成优化设计算法,该方法统一了结构优化的计算机辅助设计、计算机辅助工程分析和优化设计的模型,基于B样条的等几何裁剪分析既能准确表达几何形状,又可以用裁剪面分析方便处理任意复杂拓扑优化问题,由裁剪选择标准确定合理的拓扑结构变动方向,结构变动时无需重新划分网格,设计结果突破初始设计空间的限制,还可方便优化形状。建立了等几何裁剪灵敏度分析的计算方法,给出了等几何裁剪分析拓扑与形状集成优化算法,通过典型实例表明所用方法的正确性和有效性。     

A review of synthesis methods for additive manufacturing

With the design freedoms afforded by additive manufacturing (AM) processes, an increasing interest in shape synthesis methods has led to a variety of advances in topology optimisation methods and associated synthesis technologies. In this paper, we identify research issues related to the application of AM to shape synthesis methods, review recent advances in topology optimisation, and outline a vision for future synthesis capabilities.     

Optimal design of piezoelectric microstructures

Application of piezoelectric materials requires an improvement in their performance characteristics which can be obtained by designing new topologies of microstructures (or unit cells) for these materials. The topology of the unit cell (and the properties of its constituents) determines the effective properties of the piezocomposite. By changing the unit cell topology, better performance characteristics can be obtained in the piezocomposite. Based on this idea, we have proposed in this work an optimal design method of piezocomposite microstructures using topology optimization techniques and homogenization theory. The topology optimization method consists of finding the distribution of material phase and void phase in a periodic unit cell, that optimizes the performance characteristics, subject to constraints such as property symmetry and stiffness. The optimization procedure is implemented using sequential linear programming. In order to calculate the effective properties of a unit cell with complex topology, a general homogenization method applied to piezoelectricity was implemented using the finite element method. This method has no limitations regarding volume fraction or shape of the composite constituents. Although only two-dimensional plane strain topologies of microstructures have been considered to show the implementation of the method, this can be extended to three-dimensional topologies. Microstructures obtained show a large improvement in performance characteristics compared to pure piezoelectric material or simple designs of piezocomposite unit cells.     

Novel applications of Z-matrix to network topology analysis in the relay coordination software

The impedance matrix (Z-matrix) of power system contains much useful and unrevealed information. It has been widely used for short-circuit analysis, contingency analysis and economic dispatch. Based on the electrical coupling paths described by physical parameters of equivalent network derived from the reduced impedance matrix, some novel physical topological analysis methods to identify cut edges, cut vertices and radial paths in the relay coordination and fault analysis software are proposed. The formation of the impedance matrix is the fundamental work of the fault analysis and relay coordination. The physical methods proposed thoroughly utilise the topological information concealed in the existent Z-matrix. Compared with the traditional graph-theoretical approaches, the physical one has clearer and more significant physical implication that may help to understand and give insight into the study of the topology of the electrical network topology in power system comprehensively. Examples are presented to prove the consistency of physical topology in power system with the corresponding geometrical topology. The efficiency of the physical methods to improve network topology analysis has also been validated.