A Two-Stage Approach for Network Monitoring

A goal of network tomography is to infer the status (e.g. delay) of congested links internal to a network, through end-to-end measurements at boundary nodes (end-hosts) via insertion of probe signals. Because (a) probing constitutes traffic overhead, and (b) in any typical scenario, the number of congested links is a small fraction of the total number in the network, a desirable design objective is to identify those (few) congested links using a minimum number of probes. In this paper, we make a contribution to solving this problem, by proposing a new two-stage approach for this problem. First, we develop a binary observation model linking end-to-end observations with individual link statuses and derive necessary and sufficient conditions for whether at least one link in the network is congested. Stage I of the proposed method shows that achieving 1-identifiability with a minimum number of probes is equivalent to the familiar minimum set covering problem that can be efficiently solved via a greedy heuristic. A sequential algorithm is described, leading to a significantly lowered computational complexity vis-a-vis a batch algorithm. Next, a binary splitting algorithm originally developed in group testing is used to identify the location of the congested links. The proposed scheme is evaluated by simulations in OPNET and experiments on the PlanetLab testbed to validate the advantages of our 2-stage approach vis-a-vis a conventional (batch) algorithm.     

水布垭大坝施工期面板裂缝成因分析及处理措施

清江水布垭面板堆石坝施工过程中,大坝面板由于受混凝土干缩、温度应力及堆石坝体沉降变形的影响,使大坝面板产生了不同程度的裂缝,从宏观上分析了裂缝的成因,对裂缝进行分类,提出了限制面板裂缝发生的措施,并针对不同类型裂缝性质、裂缝宽度,制定了切实可行的处理方案,面板裂缝经修补后,都呈闭合状态,大坝面板可满足工程安全运行需要。     

Skeleton pruning as trade-off between skeleton simplicity and reconstruction error

The position and orientation of moving platform mainly depends on global positioning system and inertial navigation system in the field of low-altitude surveying, mapping and remote sensing and land-based mobile mapping system. However, GPS signal is unavailable in the application of deep space exploration and indoor robot control. In such circumstances, image-based methods are very important for self-position and orientation of moving platform. Therefore, this paper firstly introduces state of the art development of the image-based self-position and orientation method (ISPOM) for moving platform from the following aspects: 1) A comparison among major image-based methods (i.e., visual odometry, structure from motion, simultaneous localization and mapping) for position and orientation; 2) types of moving platform; 3) integration schemes of image sensor with other sensors; 4) calculation methodology and quantity of image sensors. Then, the paper proposes a new scheme of ISPOM for mobile robot — depending merely on image sensors. It takes the advantages of both monocular vision and stereo vision, and estimates the relative position and orientation of moving platform with high precision and high frequency. In a word, ISPOM will gradually speed from research to application, as well as play a vital role in deep space exploration and indoor robot control.     

杆塔倾角监测与报警系统的设计

分析杆塔的环境条件对杆塔倾角监测与报警系统提出的要求,采用太阳能电池板和蓄电池联合供电的方式,设计具有定时唤醒机制的两级MCU控制的集散控制中心,一级MCU以中断方式接收加速度计传感器采集的数据,二级MCU将数据转换成RS-485传输方式,经过光纤转换模块以光缆传输到指挥控制中心,实现了信息的可靠获取及传输;该系统体积小、成本低、微功耗、可靠性高、可维护性强,可用于各种环境的倾角指示和测量。     

篮球比赛记时记分器设计

以P89V51RB2单片机为核心结合ZLG7289B外围显示管理芯片,使用LED点阵和七段数码管共同进行显示,完成了记时与记分的功能;该装置可以显示当前节次,比赛剩余时间,双方比分,并能够根据实际情况对比赛的时间及分数进行修改。     

Parallel block tridiagonalization of real symmetric matrices

Two parallel block tridiagonalization algorithms and implementations for dense real symmetric matrices are presented. Block tridiagonalization is a critical pre-processing step for the block tridiagonal divide-and-conquer algorithm for computing eigensystems and is useful for many algorithms desiring the efficiencies of block structure in matrices. For an “effectively” sparse matrix, which frequently results from applications with strong locality properties, a heuristic parallel algorithm is used to transform it into a block tridiagonal matrix such that the eigenvalue errors remain bounded by some prescribed accuracy tolerance. For a dense matrix without any usable structure, orthogonal transformations are used to reduce it to block tridiagonal form using mostly level 3 BLAS operations. Numerical experiments show that block tridiagonal structure obtained from this algorithm directly affects the computational complexity of the parallel block tridiagonal divide-and-conquer eigensolver. Reduction to block tridiagonal form provides significantly lower execution times, as well as memory traffic and communication cost, over the traditional reduction to tridiagonal form for eigensystem computations.     

基于Lucene/Heritrix的垂直搜索引擎的研究与应用

Lucene是一个用Java写的全文索引引擎工具包,访问索引时间快,支持多用户访问,可以跨平台使用.Heritrix是一个由Java开发的、开源的Web网络爬虫,用户可以使用它从网络上抓取想要的资源.探讨了Lucene和Heritrix在构建垂直搜索引擎中的应用.     

德化陶瓷虚拟展厅

讨论了虚拟现实技术用于陶瓷展示的可行性,关键技术和系统的实现过程.利用3DSMAX和PhotoShop建立展厅和瓷器的三维模型,并使用贴图技术增强瓷器模型的真实感;使用开源的图形渲染引擎0GRE实现场景资源的组织和管理,并基于OGRE实现了虚拟展厅的实时交互和动态漫游功能.     

基于间歇控制的不确定主从Lur’e系统的指数同步

研究了不确定主从Lur’e系统的问歇控制同步问题．运用Lyapunov稳定性理论和S-过程,首先推导出保证标称主从Lur’e系统指数同步的一个充分条件．在此基础上进一步得到了具有范数有界不确定性主从Lur’e系统鲁棒指数同步的结果．这些同步判据以矩阵不等式的形式给出．另外我们还提出了一种最小化性能指标的优化策略．最后,通过两个数值例子验证了结果的有效性．     

基于SSH架构的社区卫生管理系统设计与实现

针对传统社区卫生管理系统开发的不足,基于J2EE企业级应用开发平台,整合Struts、Spring和Hibernate（SSH）开源框架技术,提出了一种多层社区卫生管理信息系统模型,实践表明,该整合框架在构建复杂业务系统中提高了开发效率和系统的可维护性,同时增强了系统的可扩展性。