南京公共宽带IP城域网建设实践

为了突破信息高速公路最后一公里的瓶颈,南京电信局于１９９９年建设成了“超级金陵热线”宽带ＩＰ试验网,目前已完成了网络架构的搭建、设备的互通性测试、应用业务的测试、小区的规划与设备改造以及网络安全策略的确立。在此基础上,南京电信局确立了２０００年宽带ＩＰ网建设项目ＢＩＰ－２０００,建设南京公众宽带ＩＰ城域网。     

Effect of corrosion potential on the corrosion fatigue crack growth behaviour of low-alloy steels in high-temperature water

The low-frequency corrosion fatigue (CF) crack growth behaviour of different low-alloy reactor pressure vessel steels was characterized under simulated boiling water reactor conditions by cyclic fatigue tests with pre-cracked fracture mechanics specimens. The experiments were performed in the temperature range of 240-288 °C with different loading parameters at different electrochemical corrosion potentials (ECPs). Modern high-temperature water loops, on-line crack growth monitoring (DCPD) and fractographical analysis by SEM were used to quantify the cracking response. In this paper the effect of ECP on the CF crack growth behaviour is discussed and compared with the crack growth model of General Electric (GE). The ECP mainly affected the transition from fast (‘high-sulphur’) to slow (‘low-sulphur’) CF crack growth, which appeared as critical frequencies ν_crit = f(ΔK, R, ECP) and ΔK-thresholds ΔK_EAC = f(ν, R, ECP) in the cycle-based form and as a critical air fatigue crack growth rate da/dt_Air,crit in the time-domain form. The critical crack growth rates, frequencies, and ΔK_EAC-thresholds were shifted to lower values with increasing ECP. The CF crack growth rates of all materials were conservatively covered by the ‘high-sulphur’ CF line of the GE-model for all investigated temperatures and frequencies. Under most system conditions, the model seems to reasonably well predict the experimentally observed parameter trends. Only under highly oxidizing conditions (ECP ? 0 mV_SHE) and slow strain rates/low loading frequencies the GE-model does not conservatively cover the experimentally gathered crack growth rate data. Based on the GE-model and the observed cracking behaviour a simple time-domain superposition-model could be used to develop improved reference CF crack growth curves for codes.     

Pseudo Optical PAM‐N Signal Using Externally Modulated Lasers

We propose a pseudo optical N‐level pulse‐amplitude modulation (PO PAM‐N) signal using a few externally‐modulated lasers (EMLs) operating at different wavelengths, which is suitable for upgrading the transmission speed over an optical link of ＜ 10 km single‐mode fiber with low‐cost components. To compare a PO PAM‐N signal with that of a standard optical PAM‐N signal, we perform experiments for evaluating the performance of a 51.56‐Gb/s PO PAM‐4 signal and standard 51.56‐Gb/s optical PAM‐4 signal. The receiver sensitivity (at ) of the PO PAM‐4 signal is 1.5 dB better than the receiver sensitivity of a standard optical PAM‐4 signal. We also investigate the feasibility of PO PAM‐N signals operating at 103.12 Gb/s, considering relative intensity noise, timing jitter, extinction ratio (ER) of EMLs, and dispersion. From the results, a PO PAM‐8 signal performs better than PO PAM‐4 and PO PAM‐16 signals at 103.12 Gb/s. Finally, we suggest a timing control method to suppress the effect of dispersion in a PO PAM‐N signal. We show that the tolerance to dispersion of a 103.12‐Gb/s PO PAM‐8 signal can be improved to ±40 ps/nm by applying a proposed scheme.     

一个基于组件式GIS技术的矿井安全与救援信息系统

本文给出了一个基于组件式GIS的井下安全与救援信息系统。首先介绍了组件式GIS技术,说明了矿井安全与救援信息系统的设计目标、井下生产相关信息,并给出了以GS组件MapX为核心,以井下安全生产和事故救援信息支持为主要功能的系统设计方案。该系统已成功开发并投入试行。     

无线局域网视频流组播优化机制

针对网络电视业务的802.11无线局域网数据传输问题,提出一种视频流组播优化机制,基于视频帧区分的方法,对关键帧I帧采用可靠组播机制传输,对非关键的B帧和P帧采用组播机制传输。仿真结果表明,该机制可以在丢帧率和数据延迟之间取得较好的折中,尤其是在无线网络带宽不足的情况下,能够有效提高数据传输后视频的观看质量。     

基于反向复用技术的100G光传输的设计与实现

基于PDM-QPSK(偏振复用-正交相位调制)以及相干光加高速DSP技术的100G传输技术在骨干网的应用越来越成熟.然而,此100G传输方案价格依然昂贵,当采用100G应用于底层网络,例如接入网以及数据中心交换机的互联互通时,价格成本考量就显得尤为突出.提出了一种新型的100G传输方案,以反向复用技术与多通道分发(MLD-Multi Lane Distribution)技术为基础并实现了基于此方案的样机设计,并且完成了48小时的160 km的无误码传输测试.实验证明,此方案基于传统单模光纤的100G传输性能良好,且是真正实现了低成本的100G传输方案.     

喷流床气化技术选择对IGCC系统能量利用效率的影响

气化炉是整体煤气化联合循环(integrated gasificationcombined cycle,IGCC)中的核心设备之一,气化技术的选择会对系统发电效率产生重要影响。文中采用GT Pro软件,分别对以壳牌(Shell)炉、德士古(GE/Texaco)炉(分激冷流程和废锅流程)和三菱(MHI)空气气化炉为合成气气源的4种IGCC系统进行流程模拟,并在此基础上探讨气化技术对IGCC系统能量利用效率的影响和内在机制。计算结果表明,整体系统的能量转化和分配受气化岛的进料形式、氧化剂选择和合成气显热回收方式等因素的影响。在采用Shell气化炉的IGCC系统中,煤炭能量更多地转化为合成气的化学能,易获得较高的系统效率;而采用GE废锅流程和空气气化炉,煤炭能量中转化为合成气物理显热的比例增加,并以蒸汽形式回收利用。     

巴基斯坦SAIF发电厂燃机小岛运行试验分析

由于燃机具备启动快速的特点,故比较适合作为电网事故情况下黑启动电源,此时燃机能够运行在小岛模式显得尤为重要.介绍了巴基斯坦SAIF发电厂燃机小岛运行试验的情况,主要分析了GE公司燃机小岛运行逻辑的设计思想,并对试验的过程及试验过程中出现的问题及解决方法进行了总结.试验证明,GE公司的燃机具备比较优良的小岛运行能力.     

9FA燃机DLN2.0+燃烧系统故障分析及处理

统计表明,DLN 2.0+燃烧系统故障是9FA燃机运行中最频率的故障。介绍 了GE公司9FA燃机DLN 2.0+燃烧系统的结构及其设备在机组启动、运行和停机过程中的动作时序,列举了出现在该系统的燃气泄漏试验失败、辅助关断阀(FSV)故障、速比阀(SRV)故障、清吹故障的原因分析及处理过程,并提出了改进措施。实际应用表明,采用改进措施后,故障率明显降低。     

A/O氧化沟污水处理工艺及自动化控制

简介A/O改良型氧化沟污水处理工艺以及污水处理的PLC自动控制系统.