MTU和MSS问题研究

如果网络不丢包而网络时快时慢,或部分应用无法使用,很大程度上可以定位为MTU&MSS问题。文章从MTU和MSS原理分析了问题产生的原因,提出了解决问题的方法。     

市电子政务外网改造故障分析及解决办法

本文从TCP/IP协议角度对市电子政务外网改造过程中,对由MTU引起故障进行讨论,分析了故障产生的原因,并给出解决方法。     

Solaris10操作系统在SUN V890服务器中的安装方法

钟吉太，岳淑华，杨志仁．Solaris10操作系统在SUN V890服务器中的安装方法，物探装备，2006，16（4）：298-300 SUN V890服务器具有强大的处理、解释功能，是在物探地震资料解释中起重要作用的高性能的工作站服务器。为了充分发挥SUN V890服务器的强大功效，必须为服务器安装Solaris操作系统，本文对Solaris操作系统在SUN V890服务器中的安装方法进行了详细地介绍。     

在MCU中通过特殊硬件进行电机控制

电流电机控制的主芯片可以大致分为三类:纯DSP、纯MCU和MCU+DSP.基于三种芯片的电机解决方案各有特点.本文使用了一种有别于上述主芯片的单芯片MTU进行电机控制设计,从控制电机同步、测量电机两相电流等应用介绍了用MTU进行设计的方案特点.     

Stationary Fuel Cells at Work – An Interim Report

Different fuel cell systems, in various numbers, have been installed and run at customers' sites using natural gas. Operational results from these field tests are presented, which demonstrate that several fuel cell systems can be used successfully to generate heat and electricity. Improved reliability and cutting costs are the most urgent challenges for commercialisation.     

基于单片机控制的Q890D钢/6061铝合金MIG焊接头组织与性能

选取TI公司开发的MSP430F149单片机为控制核心的MIG焊过程控制系统,研究焊接电流、焊接速度、焊接方向&焊枪角度和钢侧坡口角度等对Q890D钢/6061铝合金焊缝成形的影响,并在优化焊接工艺下分析焊接电流和焊接速度对Q890D钢/6061铝合金MIG焊接头界面区组织和接头力学性能的影响。结果表明:Q890D钢/6061铝合金适宜焊接方向为右焊法,适宜的焊枪角度为10°,适宜的钢侧坡口角度为45°,焊丝位置宜处于钢侧坡口中部,适宜的焊接电流和焊接速度分别为105 A和50 cm/min;不同焊接电流和焊接速度的Q890D钢/6061铝合金MIG焊接头的断裂位置都处于界面区,而MIG焊过程中界面区形成的靠近钢侧的(Fe,Cu)2Al5和靠近铝侧的(Fe,Cu)4Al13相的双层金属间化合物层结构有助于改善焊接质量。     

A review on the clad failure studies

In this paper, an attempt has been made to systematically organize the research investigations conducted on clad tube failure, so far. Before presenting the review on the clad failure studies, an introduction to different clad materials has been added, in which the effect of alloying elements on the material properties have been presented. The literature on clad failure has been broadly categorized under the headings LOCA and RIA. The failure mechanisms like creep, corrosion and pellet-clad interaction have been discussed in details. Each subsection of the review has been provided with summary table, in which the studies are arranged in the chronological order. A small section on acceptance criteria for ECCS has also been included. The last section of the review has been dedicated to the core-degradation phenomena.     

高电压锂离子电池组检测方案设计

为使电池组对外能够提供足够的能量和高电压,通常都是由多节单体电池串、并联而成.提出了一种由TM320LF2407A的DSP芯片对每个电池模块进行检测的方案.每个模块单体电池电压的采集由OZ890完成,给出了CAN接口电路,电流采集和内阻测量的原理图,该方案提高了锂离子电池组的安全性和可靠性.     

基于防火墙的路径MTU发现问题研究

通过分析路径MTU发现机制,本文深入剖析了复杂网络环境中由于防火墙、路由器等网关设备存在而引起的端到端访问异常的问题,结合FW3000防火墙设计了FAPM模型,并通过实际测试和理论分析证明了这个模型解决复杂网络环境中PMTU发现问题的有效性。     

Rate limitable and efficient discovery of path maximum transmission units

Path maximum transmission unit discovery (PMTUD) is the protocol by which a host can find the largest packet it can send through an internet protocol (IP) network to a given destination. It relies on intermediary nodes sending “packet too big” (PTB) messages in IPv6 or “datagram too big” messages in IPv4 (both henceforth referred to as PTB for the purposes of this paper). These are often completely blocked by firewalls, presumably due to a fear of PTB floods wasting the bandwidth of network links. This breaks PMTUD, forcing the use of fragmentation in IPv4 and/or suboptimal packet sizes. In IPv6, fragmentation by intermediary nodes is no longer an option. Utilizing a dynamic programming‐based solution to the generalization of a mathematical puzzle, the two‐egg problem, this work presents a family of strategies for a host to discover path MTU while obeying hard limits on the maximum number of incoming PTB messages that may be generated. This allows a firewall to mitigate PTB floods via rate limits. Moreover, these strategies are compliant with the relevant standards on PMTUD and thus can be deployed by merely changing the PMTUD algorithm implementation in TCP/IP stacks on end hosts without changing intermediary nodes' protocol behavior.