移动对象连续查询位置匿名策略

用户位置隐私保护已经成为基于位置服务领域研究的热点问题之一,现有的方法多是只针对用户单独一次查询的隐私保护,没有考虑移动过程中由于连续查询而造成的位置隐私泄露问题。主要针对连续查询下的移动对象位置隐私保护提出一种基于历史用户的虚假用户生成的位置匿名方法,该方法结合用户历史数据,通过确定合理的假用户生成区域及假用户生成时刻其空间位置,使虚假用户能够实时对真实用户位置进行保护,通过实验验证其可行性和有效性。     

基于时空关联和位置语义的个性化假位置生成方法

基于假位置的一类隐私保护方案在保护用户位置隐私的同时能够使用户获得准确查询信息,并无需依赖第三方和共享密钥.然而,当攻击者掌握一定的背景知识,例如道路时空可达信息、位置特征和用户的历史请求统计特性等,会导致假位置被识别的概率升高,降低隐私保护程度.针对上述问题,提出了基于时空关联和位置语义的个性化假位置生成算法.首先根据与前一次请求位置连续可达的条件产生假位置,然后通过建立语义树筛选出与真实位置语义相近的假位置,最后进一步筛选出与用户历史请求统计特性最接近的假位置.基于真实数据集将该算法与现有的算法进行比较,表明该算法在攻击者掌握相关背景知识的情况下,可以有效地降低位置隐私泄露的风险.     

一种基于假数据的新型轨迹隐私保护模型

基于位置服务的普及给人们的生活带来了极大的便利,但同时也带来了严重的隐私泄露问题。基于假轨迹的隐私保护技术是目前比较流行的一种方法,但是现有的大多数假轨迹方法没有考虑到用户的个性化需求。基于此问题,提出了一种改进的隐私保护模型,并按照这个模型设计了一个假轨迹生成算法。该模型包含5个参数,分别命名为短期位置暴露概率、长期轨迹暴露概率、轨迹偏移距离、轨迹局部相似度和服务请求概率,用户可以通过自身需求自定义这些度量,并通过假轨迹生成算法来生成假轨迹,从而避免隐私的泄露。实验结果表明,该算法可以在满足相同隐私的条件下生成较少的假轨迹,尤其是考虑了服务请求概率这一背景信息,该模型在保护移动对象轨迹隐私方面比之前的方案更有效。     

基于高效假轨迹的隐私保护算法研究

为了解决LBS服务中用户轨迹隐私泄露的问题,提出了一种基于高效假轨迹的隐私保护算法。首先,该方案综合考虑用户所处区域的背景信息,以划分网格的方式,统计每个网格的历史服务请求概率,确保生成的每一个假位置与对应真实位置具有相同的历史服务请求概率;其次,结合网格历史服务请求概率并通过万有引力定律模型计算出用户位置转移概率;最后,生成与真实位置转移概率最相近的k-1条假轨迹实现K-匿名。实验结果表明,该方案能够更有效地保护用户的轨迹隐私。     

面向连续查询的敏感语义位置隐私保护方案

针对连续查询位置服务中构造匿名区域未考虑语义位置信息导致敏感隐私泄露问题，通过设计[(K,θ)]-隐私模型，提出一种路网环境下面向连续查询的敏感语义位置隐私保护方案。该方案利用Voronoi图将城市路网预先划分为独立的Voronoi单元，依据用户的移动路径和移动速度，选择具有相似特性的其他[K-1]个用户，构建匿名用户集；利用匿名用户集用户设定的敏感语义位置类型和语义安全阈值，以及用户所处语义位置的Voronoi单元，构建满足[(K,θ)]-隐私模型的语义安全匿名区域，可以同时防止连续查询追踪攻击和语义推断攻击。实验结果表明，与SCPA算法相比，该方案在隐私保护程度上提升约15%，系统开销上降低约20%。     

基于速度动态差异的位置服务匿名算法

随着基于位置服务应用的日益流行,其潜在的用户隐私泄露问题也成为制约其发展的一大挑战。用户位置数据的泄露,可能导致与用户生活相关的活动、住址等隐私信息泄露,隐私问题成为位置服务中人们普遍关注的热门话题。尤其是在连续查询场景下,查询间存在着密切的联系,这就使得用户的隐私面临更大的威胁。针对这一问题,文章提出了一种连续查询下的隐私保护算法,称为基于速度的动态匿名算法(V-DCA)。在匿名处理时,考虑了用户的运动特征和趋势,也就是速度和加速度,并且利用历史匿名集合来产生新的匿名集合,在抵御查询跟踪攻击、保护隐私的同时提供了良好的服务质量。文章设计了一种连续查询隐私保护算法——基于速度的动态匿名算法(V-DCA),将用户的速度、加速度作为匿名条件之一,有效地平衡了隐私和服务质量;为了评价匿名算法,分别从隐私保障、服务质量和匿名时间3个方面提出了多个度量指标;通过在真实地图及相同环境下与其他匿名算法进行比较实验,验证了V-DCA在隐私保障、服务质量和响应时间方面的良好表现。     

位置服务中一种基于假轨迹的轨迹隐私保护方法

在位置隐私保护中,现有的方法很多都是针对用户单个位置的隐私保护,而现实情况是,用户始终处在一个连续运动的状态中,在每一个地点都有可能发出位置查询服务,由此可以产生一个用户运动的轨迹。因此如何保证这条轨迹不被攻击者识别出来就是连续查询条件下要解决的问题。针对轨迹隐私保护问题,文章提出一种基于假轨迹的轨迹隐私保护方法,在用户连续查询形成运行轨迹的同时,算法根据用户自身设定的隐私度参数要求,生成符合要求的假位置和假轨迹,通过降低攻击者的识别概率来提高轨迹隐私保护度。模拟仿真实验结果证明,与随机生成假轨迹的方法相比,在隐私保护度较高的情形下,文章方法在时间消耗和假轨迹的生成数目上都有一定的优势。     

基于马尔可夫模型的同态加密位置隐私保护方案

针对基于位置服务的位置隐私与查询隐私保护问题,提出一种基于马尔可夫模型的同态加密位置隐私保护方案。首先,随机置换匿名用户真实身份,结合用户的历史查询内容,构建马尔可夫状态转移矩阵;其次,预查询用户的历史高频率内容及马尔可夫链下的预测内容,并且存储相应结果集;最后,对该方案双预测系统的安全性进行了分析。该方案使服务器满足k+1个查询内容,并使恶意服务器或攻击者无法判定查询用户的真实身份与查询内容之间的对应关系,实现了用户位置隐私与查询隐私的保护。同时,利用同态加密密文的可计算性和保密性,实现了面向密文数据的统计分析和隐私数据的安全存储。     

连续不确定协作用户的隐私保护方法

针对分布式系统架构的基于位置服务隐私保护方法在连续位置查询服务中可能会受到的差异识别攻击,提出了一种单元格不确定性扩张的连续匿名区域隐私保护方法。该方法通过连续匿名区域内的协作用户缓存查询结果,并提供给需要同类查询结果的邻近用户的方法,降低申请者在整个连续位置查询服务的过程中与位置服务提供商之间的直接信息交互量,使得不可信的服务提供商无法获得足够的申请者信息来发动差异识别攻击,最大程度地保护了申请者的位置隐私。最后,通过安全性分析验证了所提出方法的隐私保护能力,同时利用实验验证进一步证明了该算法的安全性和执行效率。     

一种基于匿名区域变换的位置隐私保护方法

针对基于位置服务的应用中存在的用户位置隐私泄露问题,提出一种基于匿名区域变换的位置隐私保护方法。在离用户一定距离处选择一个锚点生成匿名区域后,利用邻近节点处理法计算用户邻近节点查询结果与用户真实位置之间的距离,从而实现在保护用户位置隐私的同时得到精确的查询结果。理论分析和实验结果表明,与Cloaking Region和SpaceTwist算法相比,该方法在保证较低通信开销的前提下,具有较好的位置隐私保护性能。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

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。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。