±800kV特高压换流站换流阀BOD动作导致阀组闭锁故障分析处理及优化

2014年4月8日,西北某特高压换流站极Ⅱ高端换流阀阀控主机CCPB切至主用状态时,由于极Ⅱ高端阀组换流阀控制单元VBE的B系统满足单晶闸管冗余跳闸条件(保护性触发大于3个跳闸),造成极Ⅱ高端阀组闭锁及功率转带成功,但未造成功率损失。本文首先介绍了换流阀阀控及流阀保护性触发(BOD)动作原理。其次详细说明该换流站发生换流阀BOD动作事件以及通过现场检查及试验排查的方法对故障进行分析处理方法,发现换流阀BOD动作逻辑和控保软件切换逻辑不合理。最后针对这两种不合理问题,提出相应的优化建议,避免后续工程出现类似问题。     

CFD-based method of determining form factor <Emphasis Type="Italic">k</Emphasis> for different ship types and different drafts

The value of form factor k at different drafts is important in predicting full-scale total resistance and speed for different types of ships. In the ITTC community, most organizations predict form factor k using a low-speed model test. However, this method is problematic for ships with bulbous bows and transom. In this article, a Computational Fluid Dynamics (CFD)-based method is introduced to obtain k for different type of ships at different drafts, and a comparison is made between the CFD method and the model test. The results show that the CFD method produces reasonable k values. A grid generating method and turbulence model are briefly discussed in the context of obtaining a consistent k using CFD.     

Galvanic corrosion behaviour of HE 20 / MDN 138 &amp; HE 20 / MDN 250 alloys in natural seawater

In view of their excellent mechanical properties, workability and heat treatment characteristics, MDN 138 & MDN 250 have been widely used in missile, rocket and aerospace industries. With light weight and high performance characteristics HE 20 aluminium alloy acts as an important material in defence and aerospace applications. The galvanic corrosion behaviour of the metal combinations HE 20 / MDN 138 and HE 20 / MDN 250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI’s Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN 138, MDN 250 and HE 20 of the individual metal, the mixed potential and galvanic current of the couples HE 20 / MDN 138 and HE 20 / MDN 250 were periodically monitored throughout the study period. The calcareous deposits on MDN 138 and MDN 250 were analysed using XRD. The results of the study reveal that that HE 20 has offered required amount of protection to MDN 138 & MDN 250.     

Biogeography-based combinatorial strategy for efficient autonomous underwater vehicle motion planning and task-time management

Autonomous Underwater Vehicles (AUVs) are capable of spending long periods of time for carrying out various underwater missions and marine tasks. In this paper, a novel conflict-free motion planning framework is introduced to enhance underwater vehicle’s mission performance by completing maximum number of highest priority tasks in a limited time through a large scale waypoint cluttered operating field, and ensuring safe deployment during the mission. The proposed combinatorial route-path planner model takes the advantages of the Biogeography-Based Optimization (BBO) algorithm toward satisfying objectives of both higher-lower level motion planners and guarantees maximization of the mission productivity for a single vehicle operation. The performance of the model is investigated under different scenarios including the particular cost constraints in time-varying operating fields. To show the reliability of the proposed model, performance of each motion planner assessed separately and then statistical analysis is undertaken to evaluate the total performance of the entire model. The simulation results indicate the stability of the contributed model and its feasible application for real experiments.     

基于多Agent的船舶电力系统故障诊断系统设计

在对多Agent技术和船舶电力系统故障诊断系统相关技术进行研究的基础上,设计出基于多Agent技术的船舶电力系统故障诊断系统,阐述了该系统的特点、分类、功能、结构,并就其诊断信息的交互过程做了详细的介绍。文中设计的船舶电力系统故障诊断系统能充分利用已有的诊断资源,提高故障诊断的效率,便于构造大型船舶电力系统故障诊断系统。     

某船用加压舱空调系统改进设计

本文介绍了某船加压舱空调系统制冷工况设计原理,给出了空调系统改造的相关计算以及选型设备主要性能指标。结果表明经调试检测,各项指标均达到设计要求。     

三维裂纹扩展时动态应力强度因子的有限元研究

三维裂纹在动态断裂力学中,由于其数学和物理上的复杂性,求解其动态应力强度因子受到一定的约束。文中主要介绍了利用有限元分析软件ANSYS来求解三维动态应力强度因子。     

一类可反对称化矩阵反问题的最小二乘解

利用矩阵的奇异值分解讨论了如下问题:已知X,B∈Rn×m,S=ASRn×n,A*∈Rn×m,令L={A∈S|‖AX-B‖=min},求AL,S∈L使‖A*-AL,S‖=infA∈L‖A*-A‖,给出了问题的通解表达式.     

发布订阅系统软件框架的设计与实现

随着现代装备系统的发展,装备系统中的数据传输面临着适应平台异构、动态重配置、实时性能等方面的挑战。针对这些需求,提出了一个发布/订阅系统软件框架,并基于ACE/TAO给出了发布/订阅系统的实现。最后针对该系统设计了性能测试方法。     

论水上交通事故责任认定行为的可诉性

通过对水上交通事故责任认定争议的分析,阐述了将水上交通事故责任认定行为纳入行政诉讼的受案范围的4点理由,说明了将水上交通事故调查责任认定纳入可诉性范围对人和海事管理机构都具有积极意义。