网络中多节点故障定位的探测路径选择算法

针对现有故障定位技术不能满足多节点故障定位的要求,尤其当网络中存在大量故障节点时,提出了一种基于主动探测的探测路径选择算法。该算法主要包括用于故障检测的贪婪路径选择算法和用于故障定位的禁忌链路搜索算法。在故障检测阶段,使用贪婪路径选择算法迭代地选择具有最小权重的探测路径覆盖网络中的节点。在故障定位阶段,使用禁忌链路搜索算法多次生成候选路径集以选择最合适的探测路径来解决多节点故障定位问题。在随机网络拓扑和真实网络拓扑上的仿真结果表明,与现有的节点故障定位算法相比,探测路径选择算法具有更高的成功定位率和更低的探测成本。     

Evaluating the usage of fault localization in automated program repair: an empirical study

Fault localization techniques are originally proposed to assist in manual debugging by generally producing a rank list of suspicious locations.With the increasing popularity of automated program repair,the fault localization techniques have been introduced to effectively reduce the search space of automated program repair.Unlike developers who mainly focus on the rank information,current automated program repair has two strategies to use the fault localization information:suspiciousness-first algorithm(SFA)based on the suspiciousness accuracy and rank-first algorithm(RFA)relying on the rank accuracy.However,despite the fact that the two different usages are widely adopted by current automated program repair and may result in different repair results,little is known about the impacts of the two strategies on automated program repair.In this paper we empirically compare the performance of SFA and RFA in the context of automated program repair.Specifically,we implement the two strategies and six well-studied fault localization techniques into four state-of-the-art automated program repair tools,and then use these tools to perform repair experiments on 60 real-world bugs from Defects4J.Our study presents a number of interesting findings:RFA outperforms SFA in 70.02%of cases when measured by the number of candidate patches generated before a valid patch is found(NCP),while SFA performs better in parallel repair and patch diversity;the performance of SFA can be improved by increasing the suspiciousness accuracy of fault localization techniques;finally,we use SimFix that deploys SFA to successfully repair four extra Defects4J bugs which cannot be repaired by SimFix originally using RFA.These observations provide a new perspective for future research on the usage and improvement of fault localization in automated program repair.     

主从式USV协同定位系统性能分析

为研究以距离为观测量的主从式无人水面航行器(unmanned surface vehicle,USV)协同定位系统在不同运动状态下的定位性能问题,建立一种新的协同坐标系,并在该坐标系中推导主从USV运动模型,以主从USV相对距离为观测量分析主从式USV协同定位系统的可观测性及可观测度.同时,针对不可观测路径,提出通过改变控制输入的方法以达到提高系统可观测度的目的.通过MATLAB仿真实验与水面舰艇实验,结果表明:在不同情况下,通过调整控制输入的方法改变系统的可观测度是有效的;利用所提出的分析方法可以反映协同定位系统的定位性能,验证了所得结论及方法的有效性.     

Mathematical Advancement of General Chlorine Bulk Decay Model

An accurate chlorine bulk decay model is needed to ensure that potable water meets the microbial and the chemical safeties at the treatment plant and throughout the distribution. Among the mathematical models available,the general second-order chlorine bulk decay model( GBDM) is the most fundamentally sound.Application of the GBDM,however,has been hindered by its numerous fictive parameters and lack of an analytical solution. This theoretical work removes the two obstacles. The GBDM is solved through transformation and integration. The analytical solution provides deep insights into the GBDM and facilitates the parameterization and sensitivity analysis. The background natural organic matter( NOM) is characterized with the probabilistic distribution of functional groups. It reveals that the mean of the function group distribution is correlated with the initial chlorine decay rate coefficient( κ_0). A simple formula is developed to determine κ_0 directly from the initial chlorine decay. The theoretical treatment reduces the fictive parameters to a minimum. For the common lognormal distribution,the GBDM needs only three parameters,well defined as initial chlorine demand X_0,median rate coefficient km,and heterogeneity index σ. For more complicated scenarios,composite distributions are constructed through superposition of individual distributions. A highlighted example is to predict chlorine decay in blends of different waters. With the theoretical and mathematical advancement here,the GBDM can be applied effectively to any reactive background matter in any reaction systems.     

Multi-Dimensional Pedestrian System on the New Campus of University of Macau

The Multi-dimensional Pedestrian System( MPS) is an integral part of the new campus of University of Macau. It observes the principle of "pedestrian first " and features a pedestrian-vehicle dividing system.Based on a comprehensive analysis of the location,climate,ecology and other factors of the project site,the conception of the idea of MPS and the related researches are illustrated. The transportation features of the MPS,as summarized,include multi-dimensions,short-distance and weather-resistance. Its features for the sake of livability include integration of nature, respect for the environment and sharing of landscape. Upon the completion of the project, the effects on its users were tested. Finally, some constructive rules for the construction of similar campus pedestrian systems were proposed.     

基于传声器阵列的机器人声源定位系统

随着计算机技术和信号处理技术的发展,各种具有特殊功能的机器人应用到人们的生产生活中。听觉系统可以弥补机器人视觉系统存在的不足,使机器人在黑暗或有障碍物遮挡的环境中,利用声音信息感知环境中存在的目标,并对其定位,辅助机器人工作,尤其在灾难现场搜救、军事等领域,声源定位系统具有独特的优势。针对机器人声源定位系统进行研究,设计了基于传声器阵列的机器人声源定位系统,采用平面四元传声阵列,利用广义互相关算法,实现对声源的定位,具有较高的实用价值。     

一种改进的无线传感器网络优化定位算法

节点定位是无线传感器网络实际应用需要解决的关键问题。为了在提高定位精度的同时降低成本,提出了一种改进的粒子群优化定位算法。该算法首先提出前摄估计思想,完成未知节点的区域估计,缩小并限制可行解空间,以此加快粒子群的搜索速度;然后给出了竞争进化思想的数学模型,使用该模型和自适应权重在进一步加快收敛速度的同时增强了算法的全局和局部搜索能力。仿真结果表明,对比同类算法,该算法能更有效地利用锚节点信息,降低网络成本,在计算量显著减少的同时明显提高了定位精度,并且具有对测距误差鲁棒性强的优点。     

利用多点互相关值均值的实时声源定位算法

基于可控响应功率的麦克风阵列声源定位算法在噪声和混响环境中具有较好的鲁棒性,但是利用网格搜索方法寻找可控响应功率的最大值计算复杂度很高。故提出一种新的实时声源定位算法,使用网格中多互相关值均值代替单点的可控响应功率值作为代价函数,通过多级区域收缩方法实现了代价函数最大值的空间搜索,并给出一种不显著增加计算量的互相关值求和范围的计算方式。由于利用了网格中更多的空间采样信息,因此可以使用更大尺度的搜索网格,从而降低了整个搜索过程的计算复杂度。     

无线传感器网络静态节点定位算法综述

针对无线传感器网络静态节点定位算法特点,总结了无线传感器网络节点定位的基本原理、定位算法的最新进展及其评价标准。从基于测距的静态节点定位算法和无需测距的静态节点定位算法两个方面分类讨论了典型的静态节点定位算法,并对各算法的性能进行归纳比较,说明了目前算法存在的问题,并提出未来发展趋势。     

一种语义级文本协同图像识别方法

为解决单纯依赖图像低级视觉模态信息进行图像识别准率低的问题. 考虑到许多图像中存在文本信息,提出了利用图像中的文本信息辅助图像识别的语义级文本协同图像识别方法. 该方法通过文本定位方法定位到图像中的文本块,对其进行分割、二值化、提取特征等处理;然后获取语义,提取图像底层视觉信息,计算两模态的相关性,从而得到协同后验概率; 最后,得到联合后验概率,并取其中最大联合后验概率对图像进行识别. 在自建体育视频帧数据库中,通过与以朴素贝叶斯为代表的单模态方法进行比较,方法在3种不同视觉特征下均具有更高的准确率. 实验结果表明,文本协同方法能够有效辅助图像识别,具有更好的识别性能.