Low cost and reliable anonymity protocols in P2P reputation systems

In peer-to-peer (P2P) reputation systems,each peer's trustworthiness is evaluated based on its pseudonym's rating values given by other peers. Since it is assumed that each peer has a long lived pseudonym,all the transactions conducted by the same peer may be linked by its pseudonym. Therefore,one of the fundamental challenges in P2P reputation systems is to protect peers' identity privacy. In this paper,we present two independent anonymity protocols to achieve all the peers' anonymity by changing pseudonym...     

Caching Scheme Based on Power-Law Characteristic in Unstructured P2P Networks

In order to reduce the traffic load and improve the availability of the shared resources in unstructured P2P networks, a caching scheme combining alternative index and adaptive replication (AIAR) is presented. AIAR uses random walk mechanism to disperse the caching information of resources in the network based on its power-law characteristic, and dynamically adjusts replicas according to the visit frequency on resources and the degree information of peers. Subsequent experimental results show that the proposed AIAR scheme is beneficial to improve the search performance of success rate and respond speed. In addition, compared to some existing caching scheme, AIAR can perform much better in success rate, especially in a dynamic environment.     

一种基于二叉树的P2P网络查找算法

针对P2P网络中资源查找以及其自身存在的问题,提出了一种基于二叉树的P2P网络模型。该模型借鉴了可信计算中的直接匿名认证机制、DHT、超级节点的思想,在此基础上设计了一种高效的可扩展查找算法,解决P2P网络查询延迟、冗余信息、可扩展性等关键问题。模拟实验表明,该算法能够有效减少网络带宽消耗并能显著提升P2P网络的查找效率。     

伸缩缝及支座维修更换的间接成本计算模型

伸缩缝及支座维护必然产生一定的费用,主要由直接费用和间接费用两部分组成。在已有研究成果的基础上,对间接成本的计算模型进行一定改进和创新,可供相关人员参考。     

引入图式理论提高EFL阅读能力的对策

在阅读理解中,文化背景知识起着举足轻重的作用。交互式阅读模式是建立在图式理论基础上对信息加工两种模式(自上而下与自下而上)的综合。文章以认知心理学的视角,从影响学生阅读能力的非语言因素--背景知识(图式)出发,运用图式理论,结合英语阅读学习中存在的实际问题,针对现有的问题提出一些提高EFL阅读能力的对策。     

模糊系统知识模型（Ⅱ）：范畴、知识及其近似与度量

讨论了建立在模糊系统知识模型之上的范畴与知识的概念,并通过引入粗糙集中上、下近似等基本且重要的概念,在知识模型中给出了标号集关于复合关系的上、下近似等定义,以及给出了知识模型中范畴与知识的近似及其度量方法.对于所给出的有关概念及度量方法通过举例给出了具体说明,为模糊系统知识模型一致性和完备性的讨论奠定基础.     

一种基于差分隐私保护的skyline查询方法

为了解决差分隐私保护机制中重复攻击会泄露用户隐私的问题，提出了一种基于动态页敏感度调节的skyline查询方法. 首先，提出了依据最优主导页的计算页敏感度方法，提高页敏感度计算的效率；其次，为了合理设置隐私预算值，提出了基于置信率的隐私预算值调节方法；最后，基于隐私预算值动态更新查询次数的上界，实现了基于差分隐私保护的skyline查询方法. 实验结果表明:所提出方法在隐私预算值设定小于0.8时，隐私数据的泄露数由787个降低到423个.      

Efficient Search in P2P File Sharing System

A new routing algorithm of peer-to-peer file sharing system with routing indices was proposed, in which a node forwards a query to neighbors that are more likely to have answers based on its statistics. The proposed algorithm was tested by creating a P2P simulator and varying the input parameters, and was compared to the search algorithms using flooding （FLD） and random walk （RW）. The result shows that with the proposed design, the queries are muted effectively, the network flows are reduced remarkably, and the peer-to-peer file sharing system gains a good expansibility.     

模型驱动的智能教学系统分层规划的研究

智能教学系统是计算机技术、人工智能的一个重要研究应用领域.以建构主义学习理论为指导,建立能根据学生的实际情况选取教学内容、教学模式,对学生实施个别化教学的智能教学系统是21世纪人类社会数字化教育发展的重要方向.笔者在以建构主义学习理论为指导,通过对知识、课程整体结构的分析,提出了一种新型的便于学生进行知识建构的知识模型和课程结构模型,并以此模型驱动教学规划的设计,从而实现学生的动态知识建构,以及领域无关的智能教学平台建设.这种方法在多模式智能教学系统中取得了令人满意的效果.     

Ideals of Classical Linear Lie Superalgebra P（n） over Commutative Rings

Let R be a commutative ring with identity 1. The relations between the ideals of Lie superalgebra P(n) and the ideals of R are discussed by studying the basis, center and order ideal of P(n). All ideals of P(n) are proved to be minimal and standard.     

基于自更新哈希链的安全高效车-地鉴权方案

针对下一代高速铁路无线通信系统LTE-R （long term evolution-railway）对安全性和实时性的特殊需求，基于哈希链技术，提出一种完全基于对称密码体制的的车-地通信鉴权方案. 用户归属服务器（home subscriber sever，HSS）利用身份授权主密钥为车载设备（on-board unit，OBU）生成动态可变的匿名身份（temporary identity，TID），以在接入认证请求信令中保护车载设备的隐私，同时能够抵挡去同步攻击. 在列车高速移动过程中，方案采用高效的哈希链代替认证向量完成列车和服务网络之间的双向认证，哈希链的本地更新可解决认证向量耗尽导致的全认证重启问题. 此外，通过引入身份证明票据实现基于基站协同的高效无缝切换认证. 安全性和性能分析表明:在同样条件下，所提出的全认证协议、重认证协议和切换认证协议与目前性能最优的LTE （long term evolution）标准协议相比，计算量分别下降41.67%、44.44%和45.45%，通信量分别下降62.11%、50.91%和84.91%，能够满足LTE-R接入网络的安全性和实时性要求.      

Proxy Re-Encryption Based Multi-Factor Access Control for Ciphertext in Cloud

Cloud computing provides a wide platform for information sharing. Users can access data and retrieve service easily and quickly. Generally, the data in cloud are transferred with encrypted form to protect the information. As an important technology of cloud security, access control should take account of multi-factor and ciphertext to satisfy the complex requirement for cloud data protection. We propose a proxy re-encryption (PRE) based multi-factor access control (PMAC) for cipher text in the above background. The PMAC adapts to the privacy and the protection of data confidently. We explain the motivation and some assumptions of PMAC at first. Then we define system model and algorithm. The system model and algorithm show how to create the data with corresponding accessing policy and how to grant and revoke the permission.     

圆形区域划分的k-匿名位置隐私保护方法

用户位置信息的准确度反比于用户的隐私保护安全系数k（privacy protection level）,正比于查询服务质量;为了平衡由位置信息的准确性引起的隐私保护安全与查询服务质量之间的矛盾,借助位置k-匿名模型,提出了圆形区域划分匿名方法.将整个区域划分为相切圆及相邻的4个相切圆的顶点组成的曲边菱形形成的组合区域,当用户位置区域含有的用户数量不满足隐私保护安全系数要求时,利用区域扩充公式得到合适的匿名区域.实验结果表明该方法减小了匿名区域的面积,提高了相对匿名度,从而平衡了k与QoS的矛盾;并从匿名成功率、服务质量和信息处理时间3个角度确定了基于位置k-匿名隐私保护方法的评估模型.     

隐私的边界及其内容探析

本文从"公生活"的角度出发,引进了公关系和绝对隐私等概念,研究了隐私权的保护客体(隐私)及其内容,较好地展示了隐私与公生活之间的边界,为进一步制定和实施相关的法律提供了重要的基础.     

基于Excel的测斜数据自动计算与分析

深层土体水平位移是基坑监测中的一个重要内容。在简要介绍测斜仪的基本原理的基础上,通过大量工程实践,提出一种基于Excel表格的实用快捷的数据处理模板,可供同行参考。     

An Intelligent Master Model of Computer Aided Process Planning for Large Complicated Stampings

Process planning for large complicated stampings is more complicated, illegible and multiform than that for common stampings. In this paper, an intelligent master model of computer aided process planning （CAPP） for large complicated stampings has been developed based on knowledge based engineering （KBE） and feature technology. This innovative model consists of knowledge base （KB）, process control structure （PCS）, process information model （PIM）, multidisciplinary design optimization （MDO）, model link environment （MLE） and simulation engine （SE）, to realize process planning, optimization, simulation and management integrated to complete intelligent CAPP system. In this model, KBE provides knowledge base, open architecture and knowledge reuse ability to deal with the multi-domain and multi-expression of process knowledge, and forms an integrated environment. With PIM, all the knowledge consisting of objects, constraints, cxtmricncc and decision-makings is carried by object-oriented method dynamically for knowledge-reasoning. PCS makes dynamical knowledge modified and updated timely and accordingly. MLE provides scv. cral methods to make CAPP sysmm associated and integrated. SE provides a programmable mechanism to interpret simulation course and result. Meanwhile, collaborative optimization, one method of MDO, is imported to deal with the optimization distributed for multiple purposes. All these make CAPP sysmm integrated and open to other systems, such as dic design and manufacturing system.     

ID-Based Threshold Decryption Secure Against Chosen Plaintext Attack

Introduction Inthresholddecryptioncryptosystems,the powertodecryptissharedamongasetofdecryp-tionservers.In2001,D.BonehandM.Franklin proposedapracticalidentity-basedencryption(IBE)schemefromtheweilpairing.Combining thetwoconceptstogether,some“ID-basedthresh-olddecryption”schemeshavebeenconstructed.In suchschemes,anentity'spublickeyisderiveddi-rectlyfromitsidentity.Atrustedthirdparty calledtheprivatekeygenerator(PKG)usesthe masterkeytogenerateprivatekeysforallentities.Eachdecryptionserve…     

Image Betrayal Checking Based on the Digital Fingerprint of Images on the Internet

In the Internet environment, documents are easily leaked, and divulged files spread rapidly. Therefore, it is important for privacy institutions to actively check the documents on the Internet to find out whether some private files have been leaked. In this paper, we put forward a scheme for active image betrayal checking on the Internet based on the digital fingerprint, which embeds fingerprints into privacy documents, extracts codes from the Internet images, and then finds out the divulged files by matching two groups of codes. Due to so many documents on the Internet, the number of times of code comparison is huge, which leads to a large running time. To overcome the deficiency in practical application, we optimized the process by accurate matching methods and approximate matching method. Then a method was proposed to group objects by locality sensitive hashing (LSH) process before code comparison, in order to eliminate the vast majority of unrelated pairs. Experiments prove that this method could operate with less running time and less memory.     

THE EXPRESSION AND SIGNIFICANCE OF P53 AND P21 （WAF1／CIP1） IN THYROID CARCINOMA

Thethyroidcanceristhemostcommoncarci nomaintheendocrinicneoplasms.Thyroidcarcino ma,dependingonthepathologicaltype,hastwo thoroughlypolarizedcharacteristicsofprogression. Undifferentiatedcarcinomaischaracterizedbyex ceptionallyquickprogressionwithdirep…     

妊娠滋养细胞疾病P16和P53蛋白表达及意义

目的　探讨P1 6、P5 3基因产物在正常绒毛组织、葡萄胎、恶性葡萄胎 (恶葡 )、绒毛膜上皮癌 (绒癌 )中的表达与恶性程度及预后的关系。方法　采用SP免疫组织化学技术对正常绒毛组织、葡萄胎、恶葡、绒癌组织中的肿瘤抑制基因P1 6、P5 3蛋白表达进行检测。结果　正常绒毛组织、葡萄胎、恶葡、绒癌组织中P1 6蛋白阳性率分别为 1 0 0 % (1 0 /1 0 )、75 % (3 0 /40 )、41 .7% (5 /1 2 )、2 2 .2 % (2 /9)呈递减趋势。正常绒毛组织与葡萄胎之间以及葡萄胎、恶葡、绒癌之间差异有显著性 (P <0 .0 5 ) ;正常绒毛组织P5 3蛋白不表达 ,葡萄胎表达呈弱阳性 3 0 % (1 2 /40 ) ,恶葡为83 .3 % (1 0 /2 0 ) ,绒癌为 88.9% (8/9) ,显著高于正常绒毛组织和葡萄胎 (P <0 .0 5 )。正常绒毛、葡萄胎、恶葡和绒癌中P1 6和P5 3蛋白表达之间未见明显相关。结论　恶葡及绒癌组织中P1 6蛋白低表达和P5 3蛋白过表达均有促进肿瘤细胞增殖作用 ,与滋养叶细胞肿瘤恶性程度及预后有关