三峡水电站发电机断路器设计及运用研究

三峡右岸电站是世界上首个在700 MW级水轮发电机主回路配套使用发电机断路器(简称GCB)的水电工程,其额定电流26 kA、短路开断电流160 kA。为了确保大型GCB在三峡工程中得到成功运用,进行了大量的工程设计和研究工作,解决了GCB特征参数确定、设备布置、厂内运输安装等一系列工程实际问题。对GCB在三峡水电站工程实际运用中遇到的一些问题及其有针对性地开展的分析研究工作、所采取的一些应对措施等情况作了介绍。对问题的论述及结论可为同类电站的设计提供参考。     

Comparing interpolation techniques for monthly rainfall mapping using multiple evaluation criteria and auxiliary data sources: A case study of Sri Lanka

Interpolating climatic variables such as rainfall is challenging due to the highly variable nature of meteorological processes, the effects of terrain and geography, and the difficulty in establishing a representative network of stations. While interpolation models are being adapted to include these effects, often the rainfall data contain significant gaps in coverage. In this paper, we evaluated rainfall data from an agro-ecological monitoring network for producing maps of total monthly rainfall in Sri Lanka. We compared four spatial interpolation techniques: inverse distance weighting, thin-plate splines, ordinary kriging, and Bayesian kriging. Error metrics were used to validate interpolations against independent data. Satellite data were used to assess the spatial pattern of rainfall. Results indicated that Bayesian kriging and splines performed best in low and high rainfall, respectively. Rainfall maps generated from the agro-ecological network were found to have accuracies consistent with previous studies in Sri Lanka.     

显微红外热成像技术在故障定位中的应用

电子元器件是整机的基础,在装备的生产和使用过程中,元器件工作异常将影响整个装备的正常运行,元器件发生故障时,必须迅速、准确地进行故障分析和失效定位,避免军用装备在关键时刻发生故障。显微红外热成像技术是一种对电子元器件的微小面积进行高精度非接触的测量,能够显示元器件的反常热分布,暴露不合理的设计和工艺缺陷。论文介绍了显微红外热像仪的原理及特点,举例说明了显微红外热成像技术在失效分析故障定位中的应用,对元器件的故障失效分析和有效性检测提供了指导作用。     

主成分分析法在学生成绩分析中的应用

本文从大学四年成绩的真实数据入手,利用主成分分析法,建立了数学模型,然后给出各主成分的得分函数,并结合成绩进行分析,最后得出影响成绩的主要课程,并验证了学校实行的学分绩是合理的。该研究结果为今后的教学研究和管理提供了科学的依据。     

Microsoft Windows vs. Apple Mac OS X: Resilience against ARP cache poisoning attack in a local area network

ABSTRACT

Robust security measures are integrated into new release versions of operating systems (OSs) to ensure that users have a more secure and reliable environment in which to run their daily tasks. In this article, through extensive practical experiments, we evaluate and compare the resilience of popular versions of Microsoft Windows OSs and Apple Mac OS X against Address Resolution Protocol (ARP) cache poisoning attack in a local area network (LAN). The experimental results demonstrate clearly that all tested versions of Windows OSs and Apple Mac OS X are vulnerable to the ARP cache poisoning attack, and do not deploy built-in efficient security features to prevent success of this attack. In addition, the experimental results directly contradict the common belief that Windows OSs are always less secure than Apple OSs. On the other hand, the article analyzes the efforts that have been made and the different methods that have been applied to detect and prevent ARP cache poisoning attacks. The article shows that none of these efforts and methods has been able to give satisfactory results.     

Developing a Higher-Cycled Product Design CAE Model： The Evolution of Automotive Product Design and CAE

To help corporations survive amidst worldwide quality competition, the authors have focused on the strategic development of a higher-cycled product design CAE model employing a highly reliable CAE analysis technology component model. Their efforts are part of principle-based research aimed at evolving product design and CAE development processes to ensure better quality assurance. To satisfy the requirements of developing and producing high quality products while also reducing costs and shortening development times, the effectiveness of this model was verified by successfully applying it to the technological problems of loosening bolts and other product design bottlenecks at auto manufacturers.     

一种改进的谐波电流检测方法

针对传统的ip-iq谐波电流检测方法采用锁相环虽然能得到三相电流的基频和初相角,但当电网电压发生畸变时则存在检测精度较低、电路复杂的问题,提出了一种改进的无锁相环的谐波电流检测方法;详细分析了当电网电压发生畸变时,在三相电流对称和不对称的情况下该改进方法的检测原理,并给出了该改进方法应用于单相电路谐波电流检测的实现。实验结果表明,该改进方法能够准确、实时地检测谐波电流,且算法简单。     

基于Trustie资源库的导航软件构件管理

结合导航软件生产现状与制约因素,提出对导航软件进行构件化改造,形成10大类120个共享构件。同时,利用Trustie已有成果,首先对Trustie构件资源库进行适应性改造,使之能适应导航软件生产;然后对导航软件构件在进入Trustie构件资源库之前,进行可信分级评估;最后利用该构件资源库,实现对导航软件构件的登记、查询、统计等管理,建立起导航构件资源库。该资源库的建立,极大地提高导航软件构件的可复用率,方便对构件的分类与管理,完成各类构件在导航软件协同生产环境中共享,为实现导航软件的大规模生产与敏捷制造奠定了基础。     

CAE在同步辐射装置挡光元件设计中的应用

针对第三代同步辐射装置挡光元件承受极高热负载、设计难度大的问题,综述CAE在其设计中的应用情况:借助有限元分析可以获得挡光元件关键部件吸收体的最高温度和最大应力这两个最主要设计参数;通过计算流体力学(Computational Fluid Dynamics,CFD)软件模拟可以获得吸收体中冷却管道的对流换热与流动阻力特性参数;采用热弹塑性有限元分析可以获得用于低周疲劳寿命预估的吸收体热应力应变迟滞循环.下一步工作将围绕当今研究的核心问题——基于低周疲劳的设计准则展开,包括同步辐射高热负载作用下低周疲劳裂纹的起裂寿命和扩展寿命预测,以及吸收体倾角、表面光滑度、冷却管道排布等对寿命的影响.这些研究均需要充分利用CAE的强大分析功能.     

集装箱码头三维仿真组件平台

为直观、形象地研究集装箱码头生产优化问题,采用三维仿真的方法实现集装箱码头物流信息与作业过程的可视化．基于不同业务流程的仿真要求,合理地划分静态布局、装卸设备、装卸对象、码头操作、运动学解算、数据访问、通信接口和图形渲染等组件的粒度;建立层次结构形式的组件平台,体现客观对象的逻辑关系;遵循标准COM＋规范设计岸桥、场桥和集卡等集装箱码头主要三维仿真组件．以上海振华重工（集团）股份有限公司自动化集装箱码头为例验证该组件平台的可操作性,结果表明该方法对集装箱码头装卸工艺的改进和管理水平的提升具有实际指导意义．