Measuring robustness of computing systems

System builders are becoming increasingly interested in robust design. We believe that a methodology for generating robustness metrics will help the robust design research efforts and, in general, is an important step in the efforts to create robust computing systems. The purpose of the research in this paper is to quantify the robustness of a resource allocation, with the eventual objective of setting a standard that could easily be instantiated for a particular computing system to generate a robustness metric. The paper exposes how not considering the uncertainties can result in gross overestimation of the system capacity, and shows a method for reducing the impact of uncertainty, and even use it to our advantage if the uncertainties are correlated. We present our theoretical foundation for a robustness metric and give its instantiation for a particular system.     

一种时频域联合捕捉主动声纳信号的方法

介绍了一种可应用于被动声纳的时频域联合捕捉主动声纳信号的方法及其工作流程。仿真相同噪声环境下使用该方法的发现距离与主动声纳探测距离,仿真结果表明使用该方法的发现距离远超过主动声纳探测距离,使用该方法可实现对目标的远程发现。     

空间最近点对的计算机算法研究

最近点对问题是空中交通控制系统中的一个重要问题,并且在许多领域都有应用,也是计算几何学研究的基本问题之一.利用分治法解决该问题的线性和平面情况,算法可以在O(n*logn)时间内完成.本文在此基础上,进一步实现空间最接近点的算法,并对算法的复杂性进行分析.     

基于动态规划融合多模态的足球视频事件分析

为了更好地满足用户浏览和检索视频的需要,提出一种融合文本的足球视频事件分析框架.分别从文本和视频中提取事件信息,采用动态规划的算法对2种信息进行全局匹配,对于未匹配的文本事件信息.采用一个全局概率模型估计其在视频中的事件边界.通过寻找文本与视频事件信息的最优全局匹配,有效地避免了局部匹配方法造成的漏检和误检.实验结果表明,文中方法能够快速、准确地检测事件,获得详尽的事件内容信息,性能优于局部匹配算法.     

基于搜索的面向路径字符串测试数据自动生成方法

针对字符串测试数据自动生成,讨论了字符串间的距离,将不满足路径条件的字符串谓词表示成一个实值目标函数;利用快速下降搜索算法实施目标函数极小化,实现了基于搜索的面向路径字符串测试数据自动生成方法;探讨了其测试数据生成效率与初始输入、路径处理顺序之间的关系,并与遗传算法等几种算法进行了比较．实验结果表明：该方法是一种更经济有效的测试数据生成方法．     

Oriented energy,nearness and fault diagnosis

This paper describes why the k-dimension maximal oriented energy subspace of the measurable voltage-change matrix id the optimal feature to locate faults in a population of circuits. The paper elaborately designs a "nearness" concept, which is used to construct a fault candidate set in a small size, and proposes a maximal nearness criterion. On the basis of these, the paper presents a novel algorithm to efficiently improve the accuracy and speed of fault locating.     

基于改进灰狼算法的啤酒灌装PID液位控制

目的 针对啤酒罐装液位控制存在的变负荷、多模态、PID参数整定难的问题,提出一种基于改进灰狼算法的PID参数整定方法,以提高啤酒生产的工作效率。方法 对灰狼算法进行改进,使用欧式距离变化率动态调整收敛因子,平衡算法的全局搜索能力;引入动态自适应权重因子,提高算法的优化速度和精度;与基本灰狼算法比较并用测试函数验证改进算法的性能。结果 仿真结果表明,改进后的灰狼算法在收敛速度和精度上提升效果显著;改进灰狼算法整定的PID参数的上升时间为1.9s,调节时间为5.12 s,超调量为3.78%。结论 与基本灰狼算法对比,改进灰狼算法对啤酒灌装液位PID参数进行整定,调节时间快,超调较小,可以更好地满足啤酒生产的控制要求。     

Stochastic simulation of velocity pulses of near-fault ground motions based on multivariate copula modeling

Due to the featured high-amplitude, long-period pulses in velocity or displacement time–history, the near-fault ground motion may have a stronger destructive effect on engineering structures. Therefore, studying velocity pulses modeling of near-fault ground motions has been an important topic in the earthquake engineering community. However, the variability and probabilistic correlation of pulse model parameters have not received enough attention. To this end, an elegant method for stochastic simulation of velocity pulses of near-fault ground motions is proposed based on the classical Gabor wavelet modeling and probabilistic correlation analysis of associated model parameters by multivariate copula modeling. Especially, an efficient scheme of iteratively determining the optimal copulas pertinent to edges of a complex vine structure is developed, and two parameters relevant to the near-fault ground motion records, i.e., the rupture distance and the strongest pulse orientation, are introduced which provides a physical basis for addressing the dependence structure among variables. For illustrative purposes, the ground accelerograms recorded by near-fault instruments in the 1999 Chi-Chi earthquake are used. It is shown that the multivariate copula modeling enables the efficient representation of probabilistic correlation between model parameters which is consistent with their physical mechanism. The time histories and spectral characteristics of velocity pulses of near-fault ground motions and their stochastic fluctuations with respect to the rupture distance are well simulated. While the empirical linear regression model does not meet the requirements of random vibration analysis and thus cannot guide the safety design of seismic structures.     

Computing the Kantorovich Distance for Images

Computing the Kantorovich distance for images is equivalent to solving a very large transportation problem. The cost-function of this transportation problem depends on which distance-function one uses to measure distances between pixels.In this paper we present an algorithm, with a computational complexity of roughly order (N2), where N is equal to the number of pixels in the two images, in case the underlying distance-function is the L1-metric, an approximation of the L2-metric or the square of the L2-metric; a standard algorithm would have a computational complexity of order (N3). The algorithm is based on the classical primal-dual algorithm.The algorithm also gives rise to a transportation plan from one image to the other and we also show how this transportation plan can be used for interpolation and possibly also for compression and discrimination.     

一种减少测距误差的传感器网络定位算法

接收信号强度(RSSI)常被作为无线传感器网络定位算法的测距技术,通常,获取的RSSI信号序列中同时存在随机误差和粗差两种误差,利用以往常用的算法都难以消除混合误差对RSSI测量统计数据的影响;在分析两种误差特征的基础上,提出了一种基于统计中值的加权定位算法,算法在去除粗差的基础上,能在一定程度上平滑了随机误差,算法不仅提高了定位的精度,同时提高了节点的覆盖率;理论分析和仿真结果都表明算法具有较高的定位精度和覆盖率,最优情况下定位精度较原先算法能够提高6.99%,而不可定位节点比例下降8.05%。