基于光流计算的异常拥挤行为检测算法

面向人群场景中异常拥挤行为检测,提出基于光流计算的检测方法。该方法首先采用光流微粒矢量场提取人群运动特征;然后基于社会力模型计算光流微粒之间的相互作用力;最后对相互作用力进行直方图熵值处理来实现人群行为判别。仿真实验表明,本算法可以区分人群场景中异常区域内相互作用力的大小,对异常拥挤行为进行判别和定位。     

基于光流的ATM机异常行为实时检测

异常行为检测在自助银行智能监控系统领域中有广泛的应用前景.本文针对此应用领域,提出了基于区域光流特征的异常行为检测方法.首先利用混合高斯模型来表示背景像素的变化并自适应更新背景模型,用背景差法从视频序列中提取运动前景;采用lucas-kanade光流法计算出运动区域内的光流信息.采用基于幅值的加权方向直方图描述行为,计算区域内直方图的运动熵发现候选异常区域,再利用支持向量机进行分类.从实验结果可以看出,能够较好的识别出异常事件,并且实时性较好,能够满足实际应用需求.     

基于SimpleFlow的人群场景异常运动方向区域的识别

人群视频监控对公共安全越来越重要.人群的运动方向是人群视频中的重要信息.提出基于SimpleFlow和方向直方图检测人群视频场景中运动方向异常区域的方法.实验结果表明,该方法能很好地检测人群视频中运动方向异常的场景区域,从而为辅助智能视频监控和智能视频分析提供重要的信息.     

基于运动方向的异常行为检测

提出了一种基于运动方向的异常行为检测方法. 根据不同行为的运动方向具有不同的规律性, 该方法采用块运动方向描述不同的动作, 并利用支持向量机(Support vector machine, SVM)对实时监控视频进行异常行为检测. 为了减少噪声运动的影响, 同时有效保留小幅度运动的前景目标, 在行为描述之前, 本文采用了背景边缘模型对每一视频帧进行前景帧(有目标出现的视频帧)判断. 在行为描述时, 先提取相应视频段的所有前景帧的块运动方向, 然后对这些运动方向进行归一化直方图统计得到该视频段的行为特征. 在走廊等公共场景中的实验结果表明, 该方法能够对单人以及多人的复杂行为进行有效检测, 对运动过程中目标大小的变化、光照的变化以及噪声等具有较好的鲁棒性, 而且计算复杂度小, 能够实现实时监控.     

基于运动熵的拥挤人群异常检测

视频监控在社会安全方面扮演着越来越重要的角色,在计算机视觉领域,人群异常行为检测也成为非常重要的研究课题.提出一种基于运动熵计算的人群异常检测方法.该方法在图像上散布特征点,运用光流法分组计算出各特征点的运动大小与方向,并据此建立运动直方图,用图像熵的计算方法得出图组的运动熵,运动熵及平均能量值则作为异常检测的判断依据.实验使用明尼苏达大学逃离与恐慌相关实验视频及部分网络视频,实验表明此方法拥有较强的容错能力,并能实时正确的检测出大部分异常行为的发生.     

联合加权重构轨迹与直方图熵的异常行为检测

为解决多目标打斗、抢劫等异常行为检测精度不高的问题,提出一种联合加权重构轨迹与直方图熵的异常行为检测算法。首先,采用背景相减法结合宽高比提取行人目标;然后将卡尔曼滤波器及HOG特征融入时空上下文算法中,实现短时间内被完全遮挡行人的鲁棒跟踪;最后对跟踪轨迹进行训练,构造正常行为字典并稀疏重构待检测轨迹,通过联合加权最小重构残差和直方图熵,实现对异常行为的有效检测。通过对比实验,表明该算法对于打斗和抢劫等异常行为具有较好的检测效果,在静态背景且无遮挡的情况下,检测率可达92%以上。     

基于自投影和灰度检索的视频帧中异常行为检测

针对智能监控系统,提出了一种基于运动目标灰度直方图和自身投影直方图的检索匹配方法,能够快速实现视频序列中行人的运动方向异常检测。该方法结合目标的灰度直方图和自身投影直方图在人群中快速检索匹配目标,采用目标质心运动历史记录表连续记录目标质心和运动方向,通过比较各个目标的运动方向找出运动人群中的异常目标。实验结果表明,引入目标的自身投影直方图,比只利用灰度图的灰度信息有更高的检测准确性,同时历史移动记录表可完全胜任运动目标信息记录的任务。该方法计算量小,同时利用记录质心的移动速度能实时对目标的运动情况进行预测,对运动目标的相互遮蔽有一定的鲁棒性。     

基于运动图像序列的异常行为检测*

针对公共重点区域的智能监视问题,研究了一种基于运动历史图像（motion history image,MHI）的行人异常行为检测方法。利用运动图像序列得到的MHI获取视频帧中运动目标的运动方向,由运动方向的变化分类确定人体运动模式和行为是否异常,同时给出相应的实验结果。结果表明,该方法实现简单,具有较好的实时性与鲁棒性,可以作为实时监控系统中异常行为检测的有效方法。     

基于分割集成的行人检测方法

为提高行人检测的准确率,提出基于分割集成的方法用于静态图片中的行人检测。先将每个训练样本均匀分割成若干区域,提取特征后利用AdaBoost算法对每个区域建立一个局部分类器,这些局部分类器加权组成一个全局分类器。采用不同的分割方法重复上述过程,得到多个全局分类器。为进一步提高检测效果,得到更好的平均性能,对每种分割方法分别使用方向梯度直方图、多尺度方向梯度直方图特征建立2个全局分类器。当检测新的窗口时,集成上述全局分类器,通过加权投票的方式决定最终的检测结果。在INRIA公共测试集上的实验表明,文中方法有效提高检测效果。     

基于深度学习与稀疏光流的人群异常行为识别

目前公共场所人群异常行为检测的异常种类检测准确率较低,且多数对突然奔跑等部分异常行为无法识别.为此,提出一种基于YOLO_v3与稀疏光流的人群异常行为识别算法,通过检测小团体异常为群体异常预警与采取相应的应急措施提供充足的时间.为方便定位异常发生区域,将视频分割为多个子区域,通过获取子区域的图像样本进行诱发群体异常的小团体异常检测,利用改进YOLO_v3神经网络对传统算法较难检测行人持棍、持枪、持刀与面部遮挡等异常进行检测,在未检测到上述异常诱因时,使用稀疏光流法获取人群平均动能与运动方向熵,将得到的特征数据通过PSO-ELM进行分类,区分正常行为与同向突散或无规则突散.实验结果表明,与现有同类算法相比,该算法能有效检测行人持械与面部遮挡等小团体异常,并且定位异常发生区域的准确率达到98.227%.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.