基于社会网络的(α,k)-匿名方法

随着网络技术的快速发展,大量在线社会网络的建立和使用,越来越多的人参加到社会网络中分享和交流信息,而在这种交互过程中,会产生大量的数据。这些数据中有些是用户个人生活领域中不愿意别人知道的事情,可以认为它们是用户的隐私。社会网络数据发布的隐私保护成为新兴的研究课题。本文提出了应用于社会网络的(α,k)-匿名方法,采用基于聚类的方法,对节点的属性及节点之间的关系进行保护。每个聚类中的节点数至少为k个,并且聚类中任一敏感属性值相关的节点的百分比不高于α。理论分析和实验结果表明,基于社会网络的(α,k)-匿名方法能在信息损失尽可能小的情况下有效地保护隐私。     

基于社会网络的(a,k)-匿名方法

随着网络技术的快速发展,大量在线社会网络的建立和使用,越来越多的人参加到社会网络中分享和交流信息,而在这种交互过程中,会产生大量的数据.这些数据中有些是用户个人生活领域中不愿意别人知道的事情,可以认为它们是用户的隐私.社会网络数据发布的隐私保护成为新兴的研究课题.本文提出了应用于社会网络的(a,k)-匿名方法,采用基于聚类的方法,对节点的属性及节点之间的关系进行保护.每个聚类中的节点数至少为k个,并且聚类中任一敏感属性值相关的节点的百分比不高于a.理论分析和实验结果表明,基于社会网络的(a,k)-匿名方法能在信息损失尽可能小的情况下有效地保护隐私.     

社会网络子集(θ, k)-匿名方法

针对目前社会网络邻域隐私保护相关研究并没有考虑对子集的保护,并且邻域子集中的特定属性分布情况也会造成个体隐私泄露这一问题,提出了一种新的(θ, k)-匿名模型。该模型移除社会网络中需要被保护的节点邻域子集标签后,基于k-同构思想,利用邻域组件编码技术和节点精炼方法处理候选集中的节点及其邻域子集信息,完成同构操作,其中考虑特定敏感属性分布问题。最终,该模型满足邻域子集中的每个节点都存在至少k-1个节点与其邻域同构,同时要求每个节点的属性分布在邻域子集内和在整个子集的差值不大于θ。实验结果表明,(θ, k)-匿名模型能够降低匿名成本并且最大化数据效用。     

基于聚类的高效(K,L)-匿名隐私保护

为防止发布数据中敏感信息泄露,提出一种基于聚类的匿名保护算法.分析易被忽略的准标识符对敏感属性的影响,利用改进的K-means聚类算法对数据进行敏感属性聚类,使类内数据更相似.考虑等价类内敏感属性的多样性,对待发布表使用(K,L)-匿名算法进行聚类.实验结果表明,与传统K-匿名算法相比,该算法在实现隐私保护的同时,数据信息损失较少,执行时间较短.     

A General Approach to L(h, k)-Label Interconnection Networks

Given two non-negative integers h and k,an L(h,k)-labeling of a graph G=(V,E) is a function from the set V to a set of colors,such that adjacent nodes take colors at distance at least h,and nodes at distance 2 take colors at distance at least k.The aim of the L(h,k)-labeling problem is to minimize the greatest used color.Since the decisional version of this problem is NP-complete,it is important to investigate particular classes of graphs for which the problem can be efficiently solved.It is well known that the most common interconnection topologies,such as Butterfly-like,Bene(?),CCC,Trivalent Cayley networks,are all characterized by a similar structure:they have nodes organized as a matrix and connections are divided into layers.So we naturally introduce a new class of graphs,called (1×n)-multistage graphs,containing the most common interconnection topologies,on which we study the L(h,k)-labeling.A general algorithm for L(h,k)-labeling these graphs is presented,and from this method an efficient L(2,1)-labeling for Butterfly and CCC networks is derived.Finally we describe a possible generalization of our approach.     

光RP(k)网络上Hypercube通信模式的波长指派算法

波长指派是光网络设计的基本问题,设计波长指派算法是洞察光网络通信能力的基本方法.基于光RP(k)网络,讨论了其波长指派问题. 含有N=2ⁿ个节点的Hypercube通信模式,构造了节点间的一种排列次序Xn,并设计了RP(k)网络上的波长指派算法.在构造该算法的过程中,得到了在环网络上实现n维Hypercube通信模式的波长指派算法.这两个算法具有较高的嵌入效率.在RP(k)网络上,实现Hypercube通信模式需要max{2,「5(2^n-5/3」}个波长.而在环网络上,实现该通信模式需要复用(N/3+N/12(个波长,比已有算法需要复用「N/3+N/4」个波长有较大的改进.这两个算法对于光网络的设计具有较大的指导价值.     

一种基于彩色编码技术的基序发现算法

从DNA序列中发现基序是生物计算中的一个重要问题,序列条数K=20包含基序用例的序列条数k=16的(l,d)-(K-k)问题(记作(l,d)-(20-16)问题)是目前生物学家十分关注的基序发现问题.针对该问题提出了一种基于彩色编码技术的SDA(sample-driven algorithm)搜索算法--彩色编码基序搜索算法(color coding motif finding algorithm,简称CCMF算法).它利用彩色编码技术将该问题转化为(l,d)-(16-16)问题,再采用分治算法和分支定界法来求解.在解决将(l,d)-(20-16)问题转化为(l,d)-(16-16)问题时,CCMF算法利用彩色编码技术将4 845个组合降低到403个着色,这将极大地提高算法的整体运行效率.使用模拟数据和生物数据进行测试的结果表明,CCMF算法能够快速发现所有(l,d)-(20-16)问题的基序模型和基序用例,具有优于其他算法的综合性能评价,能够用于真实的基序发现问题.同时,通过修改着色方案,CCMF算法可以用于求解一般的(l,d)-(K-k)问题,其中,k＜K.     

A method for transforming grammars into LL(k) form

Summary A new method for transforming grammars into equivalent LL(k) grammars is studied. The applicability of the transformation is characterized by defining a subclass of LR(k) grammars, called predictive LR(k) grammars, with the property that a grammar is predictive LR(k) if and only if the corresponding transformed grammar is LL(k). Furthermore, it is shown that deterministic bottom-up parsing of a predictive LR(k) grammar can be done by the LL(k) parser of the transformed grammar. This parsing method is possible since the transformed grammar always left-to-right covers the original grammar. The class of predictive LR(k) grammars strictly includes the class of LC(k) grammars (the grammars that can be parsed deterministically in the left-corner manner). Thus our transformation is more powerful than the one previously available, which transforms LC(k) grammars into LL(k) form.     

Network Design with Edge-Connectivity and Degree Constraints

We consider the following network design problem; Given a vertex set V with a metric cost c on V, an integer k≥1, and a degree specification b, find a minimum cost k-edge-connected multigraph on V under the constraint that the degree of each vertex v∈V is equal to b(v). This problem generalizes metric TSP. In this paper, we show that the problem admits a ρ-approximation algorithm if b(v)≥2, v∈V, where ρ=2.5 if k is even, and ρ=2.5+1.5/k if k is odd. We also prove that the digraph version of this problem admits a 2.5-approximation algorithm and discuss some generalization of metric TSP.     

The <Emphasis Type="Italic">k</Emphasis>-Homotopic Thinning and a Torus-Like Digital Image in <Emphasis Type="Bold">Z</Emphasis><Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

In order to discuss digital topological properties of a digital image (X,k), many recent papers have used the digital fundamental group and several digital topological invariants such as the k-linking number, the k-topological number, and so forth. Owing to some difficulties of an establishment of the multiplicative property of the digital fundamental group, a k-homotopic thinning method can be essentially used in calculating the digital fundamental group of a digital product with k-adjacency. More precisely, let be a simple closed k _i -curve with l _i elements in . For some k-adjacency of the digital product which is a torus-like set, proceeding with the k-homotopic thinning of , we obtain its k-homotopic thinning set denoted by DT _k . Writing an algorithm for calculating the digital fundamental group of , we investigate the k-fundamental group of by the use of various properties of a digital covering (Z×Z,p ₁×p ₂,DT _k ), a strong k-deformation retract, and algebraic topological tools. Finally, we find the pseudo-multiplicative property (contrary to the multiplicative property) of the digital fundamental group. This property can be used in classifying digital images from the view points of both digital k-homotopy theory and mathematical morphology.

A deterministicO(k 3)-competitivek-server algorithm for the circle

Suppose thatk mobile servers are located on a circle. Repeatedly, a request at a pointx on the circle appears. To serve this request one of the servers has to be moved tox. The cost of moving a server tox is the distance on the circle between the server's previous location andx. The decision which server to move has to be doneon-line; that is, without the knowledge of future requests. We give a deterministic on-line algorithm for making these decisions. Our algorithm isO(k ³)-competitive: for any sequence of requests, the cost incurred by our algorithm in serving this sequence is bounded (up to an additive constant) byO(k ³) times the cost of serving this sequence using the bestoff-line algorithm; i.e., an algorithm that hasa priori knowledge of the whole sequence. Our algorithm is the best deterministic constructive algorithm fork>2.     

结合调整差值变换的(K,N)有意义图像分存方案

目的 针对传统有意义分存方法存在的像素扩张和分发掩体图像视觉质量不高等问题,提出一种结合调整差值变换的(K,N)有意义图像分存方案,该方案可用于与掩体等大且同为自然图像的密图分存.方法 在分存阶段,首先用调整差值变换将密图转换为差值图和位置图;其次将差值图和位置图进行(K,N)分存,分别嵌入到掩体图像中,并使用密钥确定位置图分存信息的嵌入位置和根据位置图中不同的差值类型选择不同的差值嵌入方法;再次对密钥进行(K,N)分存,将子密钥和分发掩体对应的MD5值公布到第3方公信方作为认证码;最后将子密钥和分发掩体分发给参与者进行保管.在恢复阶段,首先核对参与者的子密钥和分发掩体对应的MD5值,若认证通过的人数小于K,则恢复失败;否则,使用认证通过的子密钥还原出密钥,然后根据密钥提取并恢复出位置图;其次根据位置图中的差值类型来提取和恢复出差值图;最后使用逆调整差值变换还原出最终密图.结果 同现有方法相比,所提策略不存在像素扩张且分发掩体图像视觉质量较高,具有较强的恶意参与者检测能力.结论 本文方法的掩体图像与密图等大且同为自然图像,同经典有意义图像分存方案相比,克服了像素扩张问题,嵌入信息后的掩体图像具有较高的视觉质量,使用第3方公信方存储的MD5值作为认证码,具有较强的恶意参与者识别能力.     

Intuitionistic (<Emphasis Type="Italic">S</Emphasis>, <Emphasis Type="Italic">T</Emphasis>)-fuzzy hyperquasigroups

The concept of intuitionistic fuzzy subhyperquasigroups in a hyperquasigroup with respect to an s-norm and a t-norm on intuitionistic fuzzy sets is introduced and their properties of such hyperquasigroups are studied. Intuitionistic (S, T)-fuzzy relations on a hyperquasigroup G are discussed. In particular, we investigate connections hyperquasigroups with binary quasigroups.     

Multi-Radio Multi-Channel无线传感器网络中信道分配和路由策略

针对无线传感器网络中传输时延长、传输冲突大和吞吐量低等问题,提出了一种在Multi-Radio Multi-Channel无线传感器网络中信道分配和路由策略.该策略动态地建立k元n立方体拓扑结构,使用优化的静态信道分配算法提高节点的吞吐量,使用维序寻径的路由算法减少传输冲突.该方法适用于网络节点稠密、节点相互之间通信冲突大的情况,并且在单跳和多跳的网络环境下均适用.实验结果表明,基于k元n立方体这一拓扑结构的信道分配和路由策略与传统方法相比,有效地减少了端到端时延,降低了网络冲突,减少了节点能量消耗,延长了网络寿命,提高了网络吞吐量.