The effects of trust and constructive controversy on student achievement and attitude in online cooperative learning environments

This study investigated the effects of trust and constructive controversy on student achievement and attitude in online cooperative learning environments. Students in one university course were randomly assigned to one of the two treatment groups after they took part in a common initial workshop on general cooperative learning skills. The “trust” and the “constructive controversy” groups received subsequent associated skills training. The overall results indicated that after each group received the treatment during online cooperative group activities, the “trust” groups had significantly higher achievement than the “constructive controversy” groups. In addition, the “trust” groups had significantly more positive attitudes toward online cooperative learning than the “constructive controversy” groups. Specifically, using “trust” building strategies was significantly more effective than using “constructive controversy” strategies for improving the ‘openness and sharing’ and ‘acceptance and support’ components of student attitudes in online cooperative learning environments.     

Support for argument structures review and assessment

Argument structures are commonly used to develop and present cases for safety, security and for other properties of systems. Such structures tend to grow excessively, which causes problems with their review and assessment. Two issues are of particular interest: (1) systematic and explicit assessment of the compelling power of an argument, and (2) communication of the result of such an assessment to relevant recipients. The paper presents a solution to these problems. The method of Visual Assessment of Arguments (VAA), being this solution, is based on the Dempster-Shafer theory of evidence applied to the assessment of the strength of arguments, and a visual mechanism of issuing and presenting assessments, supported by the so-called opinion triangle. In the paper we explain theoretical grounding for the method and provide guidance on its application. The results of some validation experiments are also presented.     

A User Authentication Protocol Combined with the Trust Model,Biometrics and ECC for Wireless Sensor Networks

In this article, a new user authentication protocol using trust model, elliptic curve cryptography and biometrics for WSNs is submitted. The result of the trust model analysis indicates that the model can improve the model’s ability of withstanding attacks from the malicious nodes. The results of safety analysis and performance analysis for our proposed user authentication protocol demonstrate that this protocol can be flexible to all sorts of common known attacks and performs similarly or better compared with some active user authentication protocols. It is suitable for WSNs which have a prominent request for the security and the performance.     

New River Village

Social affordable housing is so often the poor relation of any private development, allocated the poorest plot with the least attractive aspect. Bruce Stewart describes how at Hornsey in north London, Stock Woolstencroft has transcended these problems with considerate spatial organisation and security management. Copyright © 2007 John Wiley & Sons, Ltd.     

大规模电力系统无功优化问题的线性规划实用化算法

以原对偶内点法为基础,将信赖域思想引入线性规划算法,从而克服动态调整步长的困难。此外,采用三角分解法解修正方程,提高了计算速度。通过对一个实际的538节点系统进行数值计算,验证所提算法的有效性。     

Consumer confidence in the safety of food in Canada and the Netherlands: The validation of a generic framework

A thorough understanding of consumer confidence in the safety of food and the factors by which this is influenced is necessary for the development of adequate and effective risk management and communication regarding food safety issues. As food chains become globalized, risk management and communication are increasingly applied at international levels. As a consequence, cross-culturally valid theoretical models are needed to investigate consumer confidence in the safety of food. In this study, consumer confidence in the safety of food in Canada and the Netherlands was systematically compared. On the basis of two nationally representative samples, it was examined to what extent differences in consumer confidence between the two countries resulted from differences in the relative importance of the determinants of confidence, and differences in the means of the constructs. No differences between Canada and the Netherlands were found regarding the relative importance of the determinants, which provides support for the generalizability of the framework. However, results indicated that Dutch consumers had a higher level of optimism and a lower level of pessimism regarding the safety of food, which appeared to be mainly related to Dutch consumers’ lower level of concern about factors related to production. The results also indicated cross-national differences in consumer recall of food safety issues in the media.     

A model of a trust-based recommendation system on a social network

In this paper, we present a model of a trust-based recommendation system on a social network. The idea of the model is that agents use their social network to reach information and their trust relationships to filter it. We investigate how the dynamics of trust among agents affect the performance of the system by comparing it to a frequency-based recommendation system. Furthermore, we identify the impact of network density, preference heterogeneity among agents, and knowledge sparseness to be crucial factors for the performance of the system. The system self-organises in a state with performance near to the optimum; the performance on the global level is an emergent property of the system, achieved without explicit coordination from the local interactions of agents.     

基于信任介绍的P2P安全研究

本文在分析研究传统信任模型的基础上,结合近两年最热门的网络架构方式,建立了一种新的基于P2P网络的信任介绍机制.这个机制利用了节点过去在网络中的历史经验,建立了节点之间的信任关系,更加有效的去解决网络中信任关系,而其算法比较简洁,比一些具有复杂算法的信任模型更适合在现实网络中的应用.该机制能够增强网络可用性,具有结构简单、可靠性强的优点.     

一种基于规则的自动信任协商模型

自动信任协商中,访问控制策略规范了用户访问资源的行为从而保护敏感信息与资源,当策略本身就包含敏感信息时,则策略的暴露会泄露隐私信息;而对策略的敏感信息再次进行保护时,则增加了协商复杂性。针对策略保护的矛盾,提出一种基于规则的自动信任协商模型——RBAM。对策略进行分解,将非敏感策略与域约束归为一类,并使用Agent技术来协商双方的交互,从而达到降低协商复杂度、提高协商效率的目的。     

Construction and Preliminary Performance of Reedbed Treatment Systems at Castle Espie Wildfowl and Wetlands Trust Centre, Northern Ireland

In 1993, the Wildfowl and Wetlands Trust constructed a demonstration reedbed treatment system at its Castle Espie Visitor Centre in Northern Ireland. The objectives of the project included (a) the treatment of septic-tank effluent, (b) the protection of water quality in Strangford Lough, and (c) the establishment of a research base for constructed wetland systems. Parallel beds of equally sized sub-surface and surface flow were constructed and planted, and a research project was initiated to provide data on performance.