面向决策的信任融合模型研究

信任关系模型无论是在现实生活中还是在开放网络中都是最复杂的社会关系模型之一,是一个很难度量的抽象的心理认知,因为它涉及假设、期望、行为和环境等多种因素。借鉴以往的研究经验,综合考虑多种信任关系要素,提出了一种新的面向决策的信任融合模型。该模型基于直接信任度、间接信任度和信誉值的演化,依据信任融合获得决策信任度,为主体评判下一次的交互提供依据。为了证明信任融合模型的有效性,假设客体在ω类活动中以期望为PωX的概率从事该项活动。实验证明,信任融合模型得到的决策信任度和客体可信度的差异明显小于直接信任度、间接信任度或信誉值。     

The relationship between perceived e-service quality and brand equity: A simultaneous equations system approach

Using the data collected from the online banking users in Taiwan, we build a hierarchical model of e-banking service quality and investigate the relationships among e-service quality, trust, satisfaction, loyalty, and brand equity. Moreover, the simultaneous equations system approach is also applied to transfer the traditional satisfaction-loyalty path into the simultaneous relationships between trust and loyalty, and between satisfaction and loyalty. As the structural form coefficients demonstrate the direct relations between our research constructs, the reduced form estimates further disclose the total impacts of the quality of e-banking service on trust, satisfaction, loyalty, and brand equity, respectively. The results indicate that the perceived quality formed through interaction with an online banking service positively affects customer trust and satisfaction, which in turn influence loyalty and brand equity. The significant simultaneous relationships between trust and loyalty, and between satisfaction and loyalty, are confirmed by our data, implying that these relationships must be determined simultaneously, rather than sequentially.     

基于贝叶斯后验概率和非合作博弈的推荐算法

针对传统协同过滤推荐算法推荐精度较低等问题,提出一种基于贝叶斯后验概率预测和非合作博弈的个性化推荐算法。采用文件主题模型求取用户与其参加过的所有社交活动的主题分布,利用隐含主题概率分布表征用户兴趣度,根据信任传递机制求取用户的直接信任和间接信任,形成用户间的信任度;将用户的兴趣度和信任度等隐式特征赋予合理的先验分布,利用贝叶斯后验概率预测隐式特征后的显式反馈;依据显式反馈将推荐结果转化为非合作博弈中用户效益最大化的纳什均衡求解。仿真对比实验表明,与其他三种推荐算法相比该算法的查准率至少提高了3.13%,查全率至少提高了2.62%。     

A probabilistic reputation model based on transaction ratings

This work introduces a probabilistic model allowing to compute reputation scores as close as possible to their intrinsic value, according to the model. It is based on the following, natural, consumer-provider interaction model. Consumers are assumed to order items from providers, who each has some intrinsic, latent, “quality of service” score. In the basic model, the providers supply the items with a quality following a normal law, centered on their intrinsic “quality of service”. The consumers, after the reception and the inspection of the item, rate it according to a linear function of its quality - a standard regression model. This regression model accounts for the bias of the consumer in providing ratings as well as his reactivity towards changes in item quality. Moreover, the constancy of the provider in supplying an equal quality level when delivering the items is estimated by the standard deviation of his normal law of item quality generation. Symmetrically, the consistency of the consumer in providing similar ratings for a given quality is quantified by the standard deviation of his normal law of ratings generation. Two extensions of this basic model are considered as well: a model accounting for truncation of the ratings and a Bayesian model assuming a prior distribution on the parameters. Expectation-maximization algorithms, allowing to estimate the parameters based on the ratings, are developed for all the models. The experiments suggest that these models are able to extract useful information from the ratings, are robust towards adverse behaviors such as cheating, and are competitive in comparison with standard methods. Even if the suggested models do not show considerable improvements over other competing models (such as Brockhoff and Skovgaard’s model [12]), they, however, also permit to estimate interesting features over the raters - such as their reactivity, bias, consistency, reliability, or expectation.     

基于证据理论的云计算信任模型研究

信任模型是研究云计算中信任机制的重要问题,其研究结果可应用于云计算数据安全、服务安全,平台安全等研究.为了解决信任的量化和不确定问题,利用证据理论对信任及信任行为进行建模,并认为信任由直接的服务行为结果和间接的第三方推荐组成.提出信任的传递和聚合方式,并将建立的信任模型通过传递方式和聚合方式进行实验;结果显示该信任模型在聚合和信任行为结果纪录情况下,有利于抑制信任的不确定.     

Trust assessment of security for e-health systems

The expansive connectivity of emerging information systems has set the stage for pervasive access to healthcare services via e-health systems for selecting the best possible healthcare services. Emerging systems are expected to be highly dynamic open environments connecting diverse number of healthcare services and autonomous entities that are autonomous agents or software applications representing patients. Entities in such dynamic environments may have different security needs from e-health systems raising the challenge of trust computations regarding security. In this research, we proposed a trust assessment model of an e-health service from the viewpoint of an entity. The model contains a comprehensive architecture applicable to different types of entities, and a novel set of trust assessment metrics may be used to assess a specific property of a security system (i.e. partial metrics) or all properties (i.e. total metrics). The simulation based evaluation of proposed model in the context of a Hospital Online Appointment Service has shown that the proposed model provides better trust computation results than existing trust models for e-health systems. Furthermore, the entities are also able to assess the trust even with incomplete security information.     

Beauty is more than screen deep: Improving the web survey respondent experience through socially-present and aesthetically-pleasing user interfaces

Web surveys are rapidly becoming standard issue in many researchers’ toolkits; however, measurement error has been shown to affect web surveys to a greater extent than paper-and-pencil surveys (Couper, 2000, Manfreda and Vehovar, 2002). Principles of aesthetic design and social presence have been applied to web surveys to reduce the prevalence of such error with promising results, which were further investigated in this research. A sample of 181 first-year psychology undergraduate students participated in this study. Participants were randomly allocated to view one of eight web survey interfaces, which varied by aesthetic quality and social presence. Exploratory structural equation modeling using the partial least squares method revealed that classical aesthetic quality and social presence were both positively related to perceived ease of use of the web survey interface and positive state affect; social presence and perceived ease of use were positively related to trust in the web survey researcher; classical aesthetic quality was negatively related to negative state affect; and, expressive aesthetic quality was negatively related to perceived ease of use and positively related to positive state affect. Interestingly, expressive aesthetic quality was also positively related to negative state affect. These relationships between aesthetic quality and social presence should inform best practice web survey design recommendations, and future empirical work should extend and test the generalizability of these findings.     

A light-weight trust-based QoS routing algorithm for ad hoc networks

In a mobile ad hoc network (MANET), the lack of a trusted infrastructure makes secure and reliable packet forwarding very challenging, especially for providing QoS guarantee for multimedia applications. In this paper, we firstly introduce the concept of trust and QoS metric estimation into establishing a trust-based QoS model. In this model, we estimate the trust degree between nodes from direct trust computation of direct observation and indirect trust computation by neighbors’ recommendations. On the other hand, due to the NP-completeness of the multi-QoS constraints problem, we only take into account link delay as the QoS constraint requirement. Then, we design a trust-based QoS routing algorithm (called TQR) from the trade-off between trust degree and link delay. At last, by using NS2 we implement this algorithm based on AODV (Ad hoc On-demand Distance Vector). We compare its performance with AODV, Watchdog-DSR and QAODV. The simulation results show that TQR scheme can prevent attacks from malicious nodes and improve the security performance of the whole network, especially in terms of packet delivery ratio, average end-to-end delay, routing packet overhead and detection ratio of malicious nodes.     

基于熟人模型的移动Agent安全机制研究

信任管理技术是移动Agent安全的关键性技术之一。提出基于熟人模型的移动Agent信任管理机制,并就其安全体系结构和相关算法进行设计。实验表明该方法能有效提高移动Agent的安全性。