高斯过程下的CMA-ES在医学图像配准中的应用

为了改进协方差矩阵自适应进化策略(CMA-ES)的性能,提出了一种高斯过程协助下的协方差矩阵自适应进化策略(GPACMA-ES)。该策略利用CMA-ES中的协方差矩阵构建核函数,引入高斯过程,在线学习历史经验,并根据历史经验预测全局最优解的最有前景区域,有效地降低了适应度函数的评价次数。同时,为了提高群体的搜索效率,引入了置信区间。群体在置信区间内更高效地采样,使得算法具备更快的收敛速度和全局寻优能力。最后,将GPACMA-ES算法应用于医学图像配准中,配准精度和效率均高于标准的CMA-ES算法。     

基于社交网络信任关系的服务推荐方法

随着服务型计算的兴起,大量跨领域电子服务应运而生。用户要从众多服务中挑选出适合自己且可信的服务十分困难,因而提出高效的服务推荐算法十分必要。传统的协同推荐方法存在冷启动、数据稀疏以及实时性不好等问题,在评分数据较少时推荐效果不佳。为获得更好的推荐结果,文中在社交网络中使用信任传递机制,建立信任传递模型,由此获取任意用户间的信任度。另一方面,设计了相似性判定指标,凭借系统评分数据,求得用户间的偏好相似度。在得到用户间信任度和偏好相似度的基础上,根据社交网络的特性,动态结合两部分指标以获得综合推荐权重,再以此权重替代传统相似度衡量标准进行基于用户的协同过滤推荐。所提方法能在解决传统推荐算法问题的基础上进一步提升推荐效果,并以准确率、覆盖率为标准在Epinions数据集上进行验证,获得了较好的效果。     

Social Media and Trust during the Gezi Protests in Turkey

The Gezi Protests, an environmental sit‐in that turned into a social movement in Turkey, is often compared to the Arab Spring and the Occupy movement with regard to the importance attributed to social media. This paper examines the role that social media played during the protests, with an emphasis on how trust was built and maintained among the protestors. In‐depth interviews with 21 active Gezi protestors revealed that social trust and system trust were intertwined in actual practices. On one side, technological affordances worked as an interface that facilitated social identification, which helped in trusting the person behind the information. On the other side, technological affordances themselves invited different levels of trust, subject to both physical constraints and technological barriers.     

基于信任和时间约束的访问控制模型TTRBAC

在分析基于信任的访问控制模型TrustBAC及模型中信任级计算方法的基础上,提出在信任级计算中引入了时间因素后的TTRBAC模型,给出了时间因素影响信任级的计算方法.新模型把用户在线时长作为影响用户信任级的重要因素,提高了模型的描述能力.     

Sharing information and building trust through value congruence

This study explores how value congruence contributes to the formation of trust in e-businesses, and how trust and value congruence influence consumers to share personal information. It is hypothesized that the perceived values of organizations regarding moral, social, environmental and political causes can have an effect on the trusting beliefs of e-commerce consumers and their willingness to disclose private personal information. A total of 775 subjects rated their perceived value congruence with organizations, their trusting beliefs, and the types of information they would be willing to disclose. This study finds that value congruence not only plays a role in mediating the trust of consumers for the organizations, but it also has a strong effect on determining their willingness to disclose personal information. In some cases, the influence of value congruence is greater than that of trust, even though trust has been touted in the literature as one of the most important factors in e-commerce. This research expands prior work by using structural equation modeling to test the relative strength of the effect of value congruence on each dimension of trust and the overall trust level, as well as its direct effect on behavioral intentions in terms of information sharing for non-profit and for-profit organizations.

网格域间信任评估模型的研究

在网格域划分的基础上,提出一种域间信任关系评估模型,具有同时兼顾服务的上下文和信任的时衰性的特点,并针对网格环境中的恶意节点和恶意推荐行为,给出相应的应对机制。实验表明,该模型能够有效地解决网格环境中的恶意行为,对恶意节点进行惩罚。     

Trust fraud: A crucial challenge for China’s e-commerce market

Currently, China’s e-commerce market is growing at an unprecedented pace, however, it is faced with many challenges, among which the trust fraud problem is the biggest issue. In this article, we use Taobao as an example and conduct a thorough investigation of the trust fraud phenomenon in China’s e-commerce market. We present the development history of trust fraud, summarize its unique characteristics, and explore the reasons why so many sellers commit fraud. We further propose a dynamic time decay trust model that aims to deter trust fraud by raising its cost and promote the growth of small and medium-sized sellers. The model utilizes detailed seller ratings as the data source, and incorporates a transaction amount weight, a time decay coefficient, and three trust factors in the calculation of trust. We test the model on real transaction data from Taobao, and the experimental results verify its effectiveness. Our proposed trust model yields a practical approach to online trust management not only in the Taobao market but also for other e-commerce platforms.     

Trust-based security for the OLSR routing protocol

The trust is always present implicitly in the protocols based on cooperation, in particular, between the entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and the entire network. In our work, we are interested by trust as security solution for OLSR protocol. This approach fits particularly with characteristics of ad hoc networks. Moreover, the explicit trust management allows entities to reason with and about trust, and to take decisions regarding other entities.In this paper, we detail the techniques and the contributions in trust-based security in OLSR. We present trust-based analysis of the OLSR protocol using trust specification language, and we show how trust-based reasoning can allow each node to evaluate the behavior of the other nodes. After the detection of misbehaving nodes, we propose solutions of prevention and countermeasures to resolve the situations of inconsistency, and counter the malicious nodes. We demonstrate the effectiveness of our solution taking different simulated attacks scenarios. Our approach brings few modifications and is still compatible with the bare OLSR.     

分布式信任模型直接信任的模糊计算方法

在电子商务、数据通信和网络安全等应用系统中,信任模型是不可缺少的基本机制。但是对于Ad—hoe网络,Peer-to—Peer网络等分布式系统,由于不存在集中专用的服务器,传统的信任模型无法被采用。本文分析了保证分布式信任模型有效性的关键因素,提出了一种新的直接信任模糊计算方法,仿真数据表明,新方法比传统方法更准确。     

Trust estimation of the semantic web using semantic web clustering

Abstract

Development of semantic web and social network is undeniable in the Internet world these days. Widespread nature of semantic web has been very challenging to assess the trust in this field. In recent years, extensive researches have been done to estimate the trust of semantic web. Since trust of semantic web is a multidimensional problem, in this paper, we used parameters of social network authority, the value of pages links authority and semantic authority to assess the trust. Due to the large space of semantic network, we considered the problem scope to the clusters of semantic subnetworks and obtained the trust of each cluster elements as local and calculated the trust of outside resources according to their local trusts and trust of clusters to each other. According to the experimental result, the proposed method shows more than 79% Fscore that is about 11.9% in average more than Eigen, Tidal and centralised trust methods. Mean of error in this proposed method is 12.936, that is 9.75% in average less than Eigen and Tidal trust methods.