P2P中基于云模型和灰色系统理论的信任机制研究

针对P2P网络信任机制中没有全面考虑信任的模糊性和随机性问题,将云模型引入到信任机制中。利用灰色预测理论,对节点的行为进行预测,根据云模型的特征参数从节点的信任值平均水平和离散水平两个方面考虑一个节点是否值得信任。实验仿真表明,该机制可以有效识别出网络中行为不稳定的恶意节点,并通过降低其信任值的方法减少其参与网络交易的机会,提高了系统的交易成功率,保证了网络的安全性。     

无线传感网络节点模糊信任演化模型

针对无线传感网络中节点信任评估的模糊性以及信任决策动态演化问题,给出一种基于模糊理论的无线传感网络节点信任演化模型。该模型引入了节点的主观信任模糊性,有效提高了信任值分类的精确度。以节点信任策略选择的演化过程为基础,推导出节点信任演化过程中的复制动态方程以及在某种条件下演化稳定策略存在的定理,对传感器节点的信任管理机制做出了改进。仿真说明了模糊信任值计算模型的健壮性,验证了定理结论并分析了奖励机制对稳定状态的影响。     

DWATrust:一种基于“二次加权法”的P2P网络动态综合信任模型

针对现有的P2P网络信任模型在聚合节点信任值时对节点行为的差异性与动态性考虑不足,提出了一种基于“二次加权法的”的P2P网络动态综合信任模型—DWATrust。该模型在对节点进行评价时,首先通过引入“时序立体数据表”来记录节点在过去某几段时间内不同评价指标下的评价得分,然后通过“嫡值法”分别计算出各个时间段内各个节点对于各个评价指标的不同权值并进行第一次加权综合,得到各个节点在不同时间段内的综合信任值。最后,通过求解一个“非线性规划问题”计算出各个时间段的权值并进行第二次加权综合,得到各个节点在整个时间段上的综合信任值。由此可见,该模型不仅充分考虑到交易上下文及节点上下文的动态变化对节点信任值的影响,而且引入时间粒度来反映这种变化。仿真实验表明,该模型可以较好地识别节点进行周期性振荡欺骗等恶意行为,从而大大改善P2P网络的交易成功率。     

MANET中多角色的分簇信任评估模型

针对现有信任评估模型中簇头选择标准单一、不同角色节点信任值难以分配与更新的问题,提出一种多角色的信任评估模型。将节点分成簇头、簇成员、网关和代理4种角色,引入节点信任值、移动性、相关度等多影响因子作为簇头、网关和代理的选择标准,采用新颖簇头节点的信任值计算方式。在簇内簇头节点的信任值由代理节点监督计算。在簇间利用由簇头、代理以及网关节点形成简化网络,根据社会网中人际关系的特点分配不同关系节点的可信度。 NS2仿真实验结果表明,该模型能有效检测出恶意节点并将其隔离,保证网络的安全性。     

VANET中基于博弈论的信任模型

为了提高车载自组织网络中通信的安全性,VANET迫切需要有效的信任管理;针对该问题提出一种基于博弈论的信任模型,该模型引入了时间衰减函数来提高信任评价的准确性和动态适应能力,并在推荐信任计算中引入节点交易密度函数来计算推荐节点的推荐可信度;为了有效激励节点积极提供高质量的服务,惩罚不良行为节点,还引入博弈论,对节点的信任值进行博弈分析,并根据分析结果决定是否转发消息;通过仿真实验证明,该信任模型在抵御恶意节点方面有很好的效果,并且能够识别自私节点并能在信任节点之间建立信任,而且有效地隔离了自私节点。     

P2P网络中基于随时间推移的风险值评估的信任管理模型

针对现有的对等(P2P)网络信任管理模型中存在的问题:忽视短期交易时间与长期交易时间对信任值的不同影响以及缺少对交易对象资源的具体风险分析,在现有信任管理模型的基础之上,以不同用户对同一种类资源所提供的资源品质和风险作为关注点,引入风险值评估的概念,建立了基于随时间推移的风险值评估的信任管理模型。仿真结果表明,该模型使得恶意节点的行为得到有效控制,对交易资源的分析量化更加深入,进一步有效地帮助用户筛选出最优的交易者。     

基于H指数的网络信任管理模型

网络信任管理是通过对网络节点间的历史交易数据进行收集、分析和处理,通过建立相应的网络信任模型来提高网络的安全性。本文分析了节点信任和节点声誉的区别,给出了节点声誉的定义,并对网络中全局声誉模型进行了研究。给出了网络信任管理中基于H指数理论的全局声誉信任模型,该模型中利用网络节点的全局声誉值作为节点间是否进行交易的决策依据。     

基于声誉的机会网络信任模型

机会网络中,节点间进行交互必须考虑其他节点的可信性。针对机会网络节点间信任问题,提出基于声誉的机会网络信任模型。该模型采用贝叶斯方法计算节点的直接声誉,并将时间退变因子引入到间接声誉的计算当中,利用加权求合的方法合成信任值,根据此信任值节点双方进行访问控制并更新信任表。最后研究模型各个参数对信任值的影响,该模型能够有效地提高节点交互成功率。     

基于P2P网络的动态模糊综合信任模型

针对现有的P2P网络信任模型在聚合节点信任值时对节点行为的差异性与动态性考虑不足,提出了一种动态的模糊综合信任模型——DFCTrust,即在静态模糊综合评价的基础上加入时间衰减因子及波动惩罚因子。首先,该模型通过静态模糊综合评价的方法来计算每次交易的满意度得分,由于在计算过程中加入了交易上下文的评价因素,所以可以很好地避免恶意节点在小交易上诚信在大交易上欺骗的恶意行为;其次,在综合计算节点信任度时,引入了时间衰减因子和波动惩罚因子,这样不仅可以避免与不活跃节点交易所造成的失败,而且还可以有效地抵御节点采用周期性振荡欺骗的恶意行为。仿真实验表明,DFCTrust具有更好的动态适应能力,能够有效地处理动态恶意节点策略性的行为改变,从而提高交易的成功率。     

基于信任的节点邻居动态配置的P2P拓扑构建

P2P服务质量和P2P网络拓扑结构有着密切的关系,本文所提出的基于信任的P2P网络动态拓扑适应模型,每个节点的连接信任值根据其邻居节点的服务质量和连接信任来计算,并概率的选取连接信任值高的节点作为邻居节点,不断更新邻居列表。实验证明该模型能有效提高网络的成功下载率,并通过理论分析进一步验证了该模型对网络中恶意节点行为的抗攻击能力。运用动态构建P2P网络拓扑的方法成功地提高了网络的可用性,该方法具有一定的实用价值。     

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.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

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.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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