Trust-based group services selection in web-based service-oriented environments

Multi-agent technologies have been widely employed for the development of web-based systems, including web-based e-markets, web-based grid computing, e-governments and service-oriented software systems. In these service-oriented systems, service provider agents and service consumer agents are autonomous and rational entities, which can enter and leave the environments freely. For simplicity, we use terms ‘provider’ and ‘consumer’ to represent this two types of agents. How to select the most suitable service providers according to a service request from a consumer in such an open environment is a very challenging issue. In this paper, we propose an innovative trust model, called the GTrust model, for service group selection in general service-oriented environments. In the GTrust model, the trust evaluation for a service group is based on the functionality coverage of the group, the dependency relationships among individual services in the group, the ratings of individual services on the attributes of the service request and a similarity measurement of the extent to which reference reports can reflect the service request in terms of the priority distribution of attributes. The experimental results and analysis demonstrate the good performance of the GTrust model on the service group selection in service-oriented environments.     

基于冗余链路的校园网流量管理设计与实现

分析了目前校园网用户体验宽带不宽的主要因素,针对校园网出口冗余链路提出基于时间策略的负载均衡方案,并对校园网骨干架构做出相应调整,经过实际应用测试,保障了用户办公学习网络应用带宽,提高了校园网用户满意度。     

Statistically uniform intra-block refresh algorithm for very low delay video communication

This paper focuses on the mechanism underlying the overall delay of a real-time video communication system from the time of capture at the encoder to the time of display at the decoder. A detailed analysis is presented to illustrate the delay problem. We then describe a statistically uniform intra-block refresh scheme for very low delay video communication. By scattering intra-blocks uniformly into continuous frames, the overall delay is significantly decreased, and object changes in the scene could be presented to the end user instantly. For comparison, the overall delay and the peak signal-to-noise ratio (PSNR) performance are tested. The experiment results show that an average of approximately 0.1 dB PSNR gain on average is obtained relative to random intra-macroblock refresh algorithm in H.264 JM, and the end-to-end delay performance is significantly improved.     

DVB-S2系统中LDPC码的编码算法的研究

本文介绍了DVB-S2标准中所采用的IRA LDPC码的结构,在研究其结构的基础上分析了直接型IRA码编码技术以及串行Turbo码编码技术.采用对比特节点所对应的所有校验节点进行并行编码运算的硬件实现方法,大大提高了编码器的工作速率.     

浅谈网络安全风险的评估方法

本文通过分析网络系统风险的概念及评价体系建设原则,针对风险评估的流程进行探讨,并就应注意的几个问题提出几点建议。以期通过本文的阐述为网络管理人员更好地制定安全策略提供有效的技术支持。