无线网状网技术与应用

无线网状网(WMNs)由网状路由器节点和客户机节点组成,其中的网状路由器节点组成了无线网状网的网络骨干,其移动性很小。他们一起为无线网状网和其他常规无线网络的客户机节点提供网络的无线接入。WMNs技术结合了中心式控制的蜂窝网与分布式控制的无线自组织网的优点,可有效克服这两种技术的缺陷并显著提高无线网络的性能,已经成为下一代无线通信网络的研究热点之一。WMNs可为无线个域网、局域网、校园网、城域网的一系列应用提供高速无线宽带接入服务。虽然目前WMNs技术发展很快,但其协议栈各层仍存在许多有待研究的课题。首先简要介绍了无线网状网的结构与特点;随后重点分析了其主要的几个应用领域;最后探讨了WMNs各协议层的研究现状与关键技术,并分析了该技术存在的问题及未来的研究方向。     

Quality-of-Service Based Protection in MPLS Control WDM Mesh Networks

Intelligent methods for automatic protection and restoration are critical in optical transport mesh networks. This paper discusses the problem of quality-of-service (QoS)-based protection in terms of the protection-switching time and availability for end-to-end lightpaths in a WDM mesh network. We analyze the backup lightpath-sharing problem in such networks and study the correlation of the working lightpaths and the impact of the correlation on the sharing of the backup lightpaths. We present a multi-protocol-label-switching (MPLS) control-based fully distributed algorithm to solve the protection problem. The proposed algorithm includes intelligent and automatic procedures to set up, take down, activate, restore, and manage backup lightpaths. It greatly reduces the required resources for protection by allowing the sharing of network resources by multiple backup lightpaths. At the same time, it guarantees, if possible, to satisfy the availability requirement even with resource sharing by taking the correlation of working lightpaths into consideration. A simple analysis of the proposed algorithm in terms of computation time and message complexity indicates that the implementation of the algorithm is practical. The illustrative studies that compare the performance of 1:1, unlimited sharing, and QoS-based backup sharing algorithms indicate that QoS-based sharing achieves comparable performance as unlimited sharing, which is much better than the 1:1 backup scheme in terms of connection blocking probability, average number of connections in the network for a given offered load, and network resource utilization.     

同心筒发射中旁泄流影响的数值研究

同心筒是一种先进的新型的舰载导弹垂直发射装置。文中采用动网格技术模拟了导弹在同心式发射筒内发射的瞬态过程。探讨了发射过程中旁泄流的产生与消失原因。通过设计内外筒的合理大小可以有效减弱旁泄流的影响。通过大量的数值实验,给出了避免外筒发生雍塞的代数关系式。     

一种网格结构的雷达信号处理单元

介绍了一种采用网络结构，使用五片SHARC芯片组成的相控阵雷达信号处理单元。并介绍了此单元上基于IEEE1149.1边界扫描标准的故障诊断系统。     

基于MAX120的峰值电压检测及其与CPLD的接口

介绍了一种性能良好的A／D转换器MAX120，详细阐述了基于MAX120的数字式峰值电压检测器，并示出了其逻辑功能的Verjlog—HDL描述和与CPLD的接口电路，最后给出了在窄脉冲测试源作用下的实测结果。     

Dynamic Survivability in WDM Mesh Networks Under Dynamic Traffic

Network survivability is a crucial requirement in WDM mesh networks. In this paper, we systematically consider the problem of dynamic survivability with dynamic single link failure in WDM networks under dynamic traffic demands. Specifically, we investigate various protection schemes, such as dedicated path protection (DPP), shared path protection (SPP), dedicated link protection (DLP), shared link protection (SLP), and two restoration schemes, path restoration (PR) and link restoration (LR). Moreover, two new shared protection methods are proposed, i.e., SRLG-based shared link protection (SRLG-SLP) and SRLG-based shared path protection (SRLG-SPP). The SRLG (shared risk link group) constraint defines the availability of protection resources to a working path, which requires that any two working paths sharing the same risk of failure (or in the same SRLG) cannot share the same protection resources. Furthermore, in our study, we consider a more practical dynamic single-link failure model, in which the link-failure-interarrival time and link-failure-holding time are considered as two independent parameters. Based on this link-failure model, extensive simulations are done to analyze and compare the dynamic survivable performance of various protection and restoration schemes. Resource utilization, protection efficiency, restoration efficiency, and service disruption ratio are employed as survivable performance metrics versus traffic load, link-failure frequency, and link-failure reparation time to evaluate the survivable performance. Many meaningful results are given. In addition, we show that the developed SRLG-SLP and SRLG-SPP protection schemes perform very well in terms of protection efficiency and service disruption ratio, while sacrificing some performance in terms of resource utilization.     

从120号溶剂油中提取正庚烷并回收甲基环己烷的研究

总结了国内外正庚烷的生产状况和市场行情，分析了中小型石化企业生产正庚烷的可行件，提出采用萃取精馏分离正庚烷的方法．在间歇精馏塔塔顶温度为91-101℃、塔釜为103-110℃的条件下，可以得到58％以上正庚烷和甲基环己烷的混合液．根据物质相关性质，初步确定有关萃取溶剂，利用单级循环汽液平衡釜对初选的萃取剂进行实验研究，选定乙二醇作为萃取剂，为进一步实验研究提供依据．     

基于散乱数据点的三角网格生成算法研究

根据光学三维传感测得的数据特点，提出了一种基于动态圆的散乱数据点的三角网格生成算法。该算法效率高，得到的曲面的效果好，并且还可以根据实际情况调整动态圆的半径来改善图形的效果。本文还给出了用这种算法处理三维面形自动测量仪测量数据的实验结果。     

Relation between microstructure, properties and spark plasma sintering (SPS) parameters of pure ultrafine WC powder

A combined experimental/numerical methodology is developed to fully consolidate pure ultrafine WC powder under a current-control mode. Three applied currents, 1900, 2100 and 2700 A, and a constant pressure of 20 MPa were employed as process conditions. The developed spark plasma sintering (SPS) finite-element model includes a moving-mesh technique to account for the contact resistance change due to sintering shrinkage and punch sliding. The effects of the heating rate on the microstructure and hardness were investigated in detail along the sample radius from both experimental and modeling points of view. The maximum hardness (2700 HV10) was achieved for a current of 1900 A at the core sample, while the maximum densification was achieved for 2100 and 2700 A. A direct relationship between the compact microstructure and both the sintering temperature and the heating rate was established.     

一种矿山用钢筋网自动化焊接生产线的设计

设计一条钢筋网自动化焊接生产线，包括经料送料平台、纬料自动分料及上料机构、多点电阻点焊机、接料平台、卸料机械手。从上料到出料依靠电机、汽缸之间的协调工作来实现。并由单片机和PLC实现控制功能，上位机用MCGS组态软件在整个过程监视现场，采集工作状态及参数，起到监控作用。