基于验证方式的系统安全设计

本文给出了关于系统安全方式的集中设计及实现,主要是通过验证方式来保证系统的安全,给出了用户验证和一般性字符验证的设计及实现。     

基于兴趣的用户聚类分析在入侵检测中的应用

在入侵检测中对用户进行聚类,可以改善安全分析的效率,有助于发现潜在非法用户.在聚类中提出按照访问兴趣对用户进行聚类分析,在用户访问兴趣度量中综合考虑网页内容和浏览路径因素.在聚类分析中,依据访问兴趣定义提出新的相似度计算方法.利用传递闭包法对用户进行聚类.算法可以提高用户聚类的准确性,试验结果表明该算法是有效的.     

基于视觉的车辆运动目标轨迹检测

运动目标状态分析已经成为计算机视觉研究的焦点问题,该文在介绍了运动目标成像系统的基础上,提出了基于帧间差分和差分背景图像信息融合的自适应背景模型以适应外界环境的变化,将α-β滤波的预测信息来提高聚类分析的实时性,同时将聚类结果来预测运动目标在下一帧图像的位置,根据运动的平滑性进行帧间匹配,从而有效地获得多目标轨迹。     

A multi-level, multi-theory perspective of information technology implementation

Abstract.  Much of information technology (IT) implementation research has focused on individuals' acceptance of IT by examining their behaviour when faced with new IT and the antecedents of these behaviours. As they are frequently undertaken within a project framework, IT implementations also entail the application of project management practices in order to be successful. Based on the premise that antecedents of lower level theories are frequently determined by the outcomes of a higher level theory, the present paper illustrates how organizational-level decisions, examined from the perspective of economics theories, can help explain the antecedents of project risk management at the project and individual levels. To do so, the paper describes an IT implementation effort which went through three phases; the first two of which were abandoned versions of the same project. An organizational-level analysis of the case from an economics perspective and its project-level analysis from a risk management perspective show how organizational-level decisions influenced the antecedents at the project and individual levels, providing a more complete understanding of the IT implementation in question, an understanding which neither a theory approach nor a level perspective could provide on its own.     

基于综合时空特性的混合式轨迹压缩算法

针对车辆全球卫星定位系统(GPS)中如何降低轨迹数据存储空间,提高数据分析及传送速度等问题,提出一种基于综合时空特性的混合式轨迹压缩算法.该算法一方面采用了新的综合时空特性的在线轨迹压缩策略,利用GPS数据的位置信息、时间信息、方向角、速度信息进行轨迹特征点的综合判断,以更准确地选取特征点;另一方面,采用了在线与批处理相结合的混合式轨迹压缩策略,定时采用道格拉斯批量压缩算法对在线压缩的轨迹集进行二次压缩,以提高轨迹的压缩效率.实验结果表明,较现有的时空特性压缩算法,新的综合时空特性在线轨迹压缩策略虽然在压缩率上略有下降,但压缩误差有显著减小.进一步采用混合式压缩策略后,通过选取适当的批处理时间周期,所提算法在压缩率和压缩误差上较现有的时空特性算法均有所改进.     

MSDA: multi-subset data aggregation scheme without trusted third party

Data aggregation has been widely researched to address the privacy concern when data is published,meanwhile,data aggregation only obtains the sum or average in an area.In reality,more fine-grained data brings more value for data consumers,such as more accurate management,dynamic price-adjusting in the grid system,etc.In this paper,a multi-subset data aggregation scheme for the smart grid is proposed without a trusted third party,in which the control center collects the number of users in different subsets,and obtains the sum of electricity consumption in each subset,meantime individual user’s data privacy is still preserved.In addition,the dynamic and flexible user management mechanism is guaranteed with the secret key negotiation process among users.The analysis shows MSDA not only protects users’privacy to resist various attacks but also achieves more functionality such as multi-subset aggregation,no reliance on any trusted third party,dynamicity.And performance evaluation demonstrates that MSDA is efficient and practical in terms of communication and computation overhead.     

融合用户信任度的概率矩阵分解群组推荐算法

利用推荐系统进行群组推荐时,群组成员之间的交互关系对推荐结果有很大影响,但传统的群组推荐算法较少考虑用户信任度的重要性,致使社交关系信息不能得到充分利用。在群组融合时考虑群组内用户间的交互关系,提出一种基于用户信任度和概率矩阵的群组推荐算法。在获取用户信任度数据后,使用概率矩阵分解（PMF）算法补全信任度矩阵并进行归一化处理,得到相似度矩阵,同时在后验概率计算过程中加入用户间的信任度因素,通过极大化后验概率获得预测评分。在此基础上,对群组中用户的权重进行归一化处理,使用基于用户交互关系的权重策略融合群组成员偏好,得到最终的推荐结果。在Epinions和FilmTrust数据集上的实验结果表明,该算法可使融合结果更具群组特性,同时提高推荐结果的可靠性和可解释性,且均方根误差和命中率均优于PMF、NeuMF、RippleNet等对比算法。     

Effects of User Request Patterns on a Multimedia Delivery System

Because of their size, service times, and drain on server resources, multimedia objects require specialized replication systems in order to meet demand and ensure content availability. We present a novel method for creating replication systems where the replicated objects' sizes and/or per-object service times are large. Such replication systems are well-suited to delivering multimedia objects on the Internet. Assuming that user request patterns to the system are known, we show how to create replication systems that distribute read load to servers in proportion to their contribution to system capacity and experimentally show the positive load distribution properties of such systems. However, when user request patterns differ from what the system was designed for, system performance will be affected. Therefore, we also report on results that reveal (i) how server loads are affected and (ii) the impact two system design parameters (indicators of a system's load distribution qualities) have on server load when request patterns differ from that for which a system was designed.     

用对偶映射原理规划和分析机器人轨迹运动

在研究机器人广义位姿的基础上,依据从基坐标系列任一坐标系的旋转变换可以通过绕基坐标系中的瞬时转动轴的等效旋转来实现的原理,提出用等效角位移矢量来描述机器人姿态以及用姿态旋量及其 Pl(u|¨)cker线坐标来描述机器人的位姿.依据对偶数代数理论中关于三维欧氏空间中的有向直线与三维对偶空间中的点具有一一对应关系的对偶映射原理,在对偶空间中对姿态旋量所映射的点进行规划,从而找到一种机器人位姿轨迹生成和运动分析新方法,文末算例说明上述原理和推导的正确性.     

Towards automatic evaluation of multimodal user interfaces

The evaluation of the usability and the learnability of a computer system may be performed with predictive models during the design phase. It may be done on the executable code as well as by observing the user in action. In the latter case, data collected in vivo must be processed. The goal is to provide software supports for performing this difficult and time consuming task.

The paper presents an early analysis of, and experience relating to, the automatic evaluation of multimodal user interfaces. With this end in view, a generic Wizard of Oz platform has been designed to allow the observation and automatic recording of subjects' behavior while they interact with a multimodal interface. It is then shown how recorded data can be analyzed to detect behavioral patterns, and how deviations of such patterns from a data-flow-oriented task model can be exploited by a software usability critic.