基于相对编辑相似度的近似重复视频检索和定位

为有效对近似重复视频进行检索和定位,提出了一种基于相对编辑相似度的检索和定位算法.算法包括基于局部特征的视频编码和基于相对编辑相似度的在线检索和定位两部分.基于局部特征的视频编码首先提取数据库视频的关键帧,然后在关键帧中提取Root-SIFT特征描述符并应用层次K-Means聚类算法构建词典,之后将关键帧量化至词袋模型的单词并编码.基于相对编辑相似度的在线检索和定位首先对查询视频进行编码,然后应用相对编辑相似度算法,筛选近似重复视频并对近似重复片段进行定位.实验结果表明,LD算法比Yeh等提出的算法在平均F₁评价准则上效果要高8.55%,并且NDCR降低为原来的29%,效果提升明显.      

Multicategory Purchase Incidence Models for Partitions of Product Categories

We analyze multicategory purchases of households by means of heterogeneous multivariate probit models that relate to partitions formed from a total of 25 product categories. We investigate both prior and post hoc partitions. We search model structures by a stochastic algorithm and estimate models by Markov chain Monte Carlo simulation. The best model in terms of cross‐validated log‐likelihood refers to a post hoc partition with two groups; the second‐best model considers all categories as one group. Among prior partitions with at least two category groups a five‐group model performs best. Effects on average basket value differ for the model with five prior category groups from those for the best‐performing model in 40% and 24% of the investigated categories for features and displays, respectively. In addition, the model with five prior category groups also underestimates total sales revenue across all categories by about 28%. Copyright © 2016 John Wiley & Sons, Ltd.     

The effects of forest fragmentation on the population ecology and natural history of a funnel-web spider

Habitat fragmentation strongly affects the abundance, distribution, body size and population genetics of invertebrates. Urban growth in Brazil has led to severe fragmentation, especially in the Atlantic Forest and savannas. The effects of this fragmentation on the common funnel-web spider Aglaoctenus lagotis were examined in two forest fragments within the interior savanna: a smaller fragment within an urban environment and a larger fragment within a rural environment. The reproductive period occurred in October, coinciding with the beginning of the rainy season, when the species was aggregated in the two forest fragments. The smaller fragment contained a larger population, and the spiders had a larger average prosoma size and web area. The presence of a larger population in a smaller area within the urban centre may reflect a limited dispersal ability, reduced predator abundance or low interspecific competition. The larger prosoma length and web area in the smaller habitat fragment suggest greater resource availability and a higher probability of capturing prey in the urban environment. In both areas, a larger number of capture threads was positively correlated with the presence of inquiline spiders in the webs. The genetic data indicate close similarity between and within the two areas, indicating that the species has low genetic variability or that the areas studied, consistent with their proximity, have separated only recently. Most savannas and forests in midwestern Brazil have recently undergone severe fragmentation, and further studies of this nature are needed.     

基于模糊信息增益的图像相关性度量

针对图像中所含有的统计概率不确定信息以及模糊不确定信息,提出了一种综合图像概率信息与模糊信息的新模糊信息增益度量方法来比较目标图像与参考图像之间的相关度,从而为图像相关匹配与检索提供强有力的依据.实验结果表明,该方法是有效的.     

千兆以太网1000BASE-T收发器物理编码子层系统及芯片设计

提出了一种优化而可行的系统结构,并以硬件实现了千兆以太网物理编码子层.该系统主要电路模块包括:递归式系统卷积码和网格编码器,以达到约6 dB的编码增益;优化的逻辑电路,以实现符号映射,替代了约6 KB的ROM;并行搜索阵列电路,以实现物理编码子层的训练.仿真及FPGA验证结果表明,该系统的关键路径时延小于7 ns,符合802.3标准.     

基于改进乌鸦搜索算法的无人艇新型路径规划策略

鉴于无人艇的实际航行需求,所规划的路径应满足顺滑性和经济性要求,为此提出一种基于改进乌鸦搜索算法和新型路径拟合方法的路径规划策略。文中提出一种新型路径拟合方法,用于优化转向点的数量并对转向点进行圆弧过渡处理,从而缩短路径长度,并保证无人艇在航速稳定的情况下实现转向,在此基础上提出一种改进的乌鸦搜索算法,用于优化路径转向点的位置。算法的改进主要体现在3个方面：采用反向学习策略以提高初始种群质量及多样性;提出一种动态变化的意识概率以提高算法局部和全局的搜索能力;采用莱维飞行策略以改善搜索的方向性和有效性。仿真结果表明,所提出的新型路径拟合方法优于B样条曲线拟合方法和直线段拟合方法。迭代计算和方差分析结果表明：在优化新型拟合路径方面,所提出的改进乌鸦搜索算法相较于标准乌鸦搜索算法、差分进化算法和遗传算法具有更高的收敛精度和鲁棒性,能更高效地处理无人艇路径规划的实际问题。     

装配生产线任务完成时间延迟的响应策略

针对实际装配生产线中由各种干扰引起的任务完成时间延迟,将不平衡问题缩小到动态响应区,并基于局部搜索算法的基本原理以及数组的读取规则,编制了改进的嵌套式搜索算法.分别制定了单个和多个动态工人时的响应策略,得出多人共同服务整个生产线的策略优于分别服务策略,且用算例分析验证了这种策略的有效性.     

简单界约束非线性方程组的不精确线搜索法

提出一种用非单调线搜索方法求解简单界约束非线性方程组,算法采用满足Armijo条件的不精确线搜索技巧,并使用非单调结构,将当前函数最大值的下降改进为函数平均值的下降,推广了算法的适用范围.最后进行了数值试验,结果表明,算法十分有效.     

螺旋流输沙相似律探讨

本文从分析螺旋流流态入手，考虑泥沙的运动状态相似，讨论了螺旋流中均匀泥沙在有效重力和绕流阻力作用下成为悬移质的相似律，以及泥沙的起动相似和悬移相似的同一性问题；分析了螺旋流输沙过程中沿程阻力损失。它为螺旋流输沙的试验研究提供了可靠的理论依据。     

基于时间序列的数控设备状态智能评判方法

针对因异构数控系统多样造成设备数据采集和状态评判困难的问题,设计一种通用的数据采集和设备状态智能评判方法. 首先由能耗信号采集器采集设备加工时的能耗信息并分析能耗特征. 采用加工仿真或预先采集的方法,收集各NC代码加工时设备主轴的能耗信息,进行信号变换形成标准能耗信息库. 然后检测数控设备的能耗信息并视为时间序列,应用时间序列的相关理论和方法对信号进行变换,采用基于编辑距离的相似性度量方法,将该时序信息和标准信息库中的信息进行比对,识别判断数控设备的加工工件类别和状态,并进行统计分析. 在此基础上,设计开发了数控设备状态智能采集系统,实现了设备数据的采集. 最后,通过实例验证该方法的可行性与可靠性.