网络型电子图书探析

网络型电子图书是近年来发展迅速的一种新型图书资源。文章在探究网络电子图书内涵与特性的基础上 ,归纳了其主要信息源 ,并分析了其发展的主要问题及解决之道。     

集群Web服务器系统及负载平衡技术在情报信息网中的应用

随着集群的广泛应用, 集群管理的重要性显得越来越明显。分析了负载平衡集群服务器的结构和特点。探讨了基于情报信息网络负载平衡的主要技术。网络负载平衡提高了诸如Web 服务器、FTP 服务器和其它关键任务服务器上的服务程序的可用性和可伸缩性。     

关于建立省际卫星传播公司的建议

在全球化的今天 ,开放是惟一可行的对策。全国性竞争是进行国际竞争的前提和预演 ,要开展全国性竞争 ,必须有一个实力足以和中央电视台“叫板”的真正对手。为此 ,本文提出建立省际卫星传播公司以提高中国电视竞争力的一个大胆建议。其制度安排类似欧洲及世界上其他一些国家广播电视实行的双重体制。     

浅论西部民族地区省级卫视的发展路径

西部民族地区大多地处边疆,经济、科技、经营理念相对落后,但丰富的民族文化资源却独具特色。民族地区卫视应当发挥身处民族文化资源富矿的独特优势,以民族文化传播作为主要频道定位,打造优势节目、调整传统思维,以期在新一轮竞争中有所作为。     

E-Mail as Spectroscopy: Automated Discovery of Community Structure within Organizations

We describe a method for the automatic identification of communities of practice from e-mail logs within an organization. We use a betweenness centrality algorithm that can rapidly find communities within a graph representing information flows. We apply this algorithm to an initial e-mail corpus of nearly 1 million messages collected over a 2-month span, and show that the method is effective at identifying true communities, both formal and informal, within these scale-free graphs. This approach also enables the identification of leadership roles within the communities. These studies are complemented by a qualitative evaluation of the results in the field.     

卫星云图的三维显示系统

讨论了卫星红外云图的立体网格显示和三维真实感显示的设计和实现,为显示云顶的温度变化情况和云系的构造提供了比较直观的手段。     

On exploiting propagation delays for passive target localization using bearings-only measurements

For many cases, target localization accuracy can significantly improve by accounting for the propagation delay between the target source and the sensors. This paper considers when it is advantageous to compensate for the propagation delay for the case of a network of nodes where each node consists of an array of sensors. Each node calculates a direction of arrival (DOA) from the raw data, and these DOAs are combined to localize the target. First, we consider the case when no prior data are given and the localization occurs using DOA measurements from a single snapshot. Such localization methods are necessary to initiate a target track. Finally, we investigate the case where an extended Kalman filter is used to aggregate measurements over multiple snapshots.     

On-line learning networks: Framework and scenarios

The idea of using the internet as a platform to mediate social interactions and learning at different levels has progressively affirming itself, and this has given rise to a huge number of spontaneous and planned collectives, which are often described as on-line learning networks. On-line learning networks create value through the combination of content and people’s knowledge. They can vary widely in the strength and permanence of their connections and the resources necessary to maintain them. Aspects of both a pragmatic and social nature need to be carefully considered in the process of initiation of on-line learning communities. This paper considers learning networks from the perspective of the potential they offer to the strengthening of relationships among institutions, groups, and people sharing a common interest in computer-enhanced learning. Some case studies are analysed and an analytical framework is sketched out to guide observations and to provide a lens through which case studies can be interpreted. The final goal is to delineate a reference for identifying strong and weak elements in virtual networks and to examine under what conditions they are succeeding. In addition, some possible scenarios for on-line networks are delineated along two main lines: the organisation and structure of the network and its level of establishment.

The Quality of Online and Offline Relationships: The Role of Multiplexity and Duration of Social Relationships

Recent studies have shown that adolescents use the Internet not only to maintain social relationships with distant relatives and friends but also to create new relationships online; some of these friendships become integrated into their social circle. Research has focused mainly on the effect of the Internet on existing relationships or the nature of online-only ties, so studies comparing the quality of online and face-to-face relationships are missing. The goal of this study is to bridge this gap. In keeping with previous studies on social association, we argue that the quality of social relationships is dependent on duration and diversity of topics and activities carried together. Time is important, as it facilitates the development of a collective shared history and identity. Intimacy develops through the participation in shared activities and discussion of diverse issues of personal concern. Using a representative sample of the adolescent population in Israel, we find that closeness to a friend is a function of social similarity, content and activity multiplexity, and duration of the relationships. Friendships originated in the Internet are perceived as less close and supportive because they are relatively new and online friends are involved in less joint activities and less topics of discussion. The implications of the findings are discussed.     

卫星电源测试评估系统的初步研究

介绍了卫星电源基本体系结构以及卫星电源测试评估方法 ,建立了基于虚拟仪器概念的卫星电源测试评估系统 ,并对一个简单的非调节母线卫星电源系统模型进行测试 ,给出了结果分析 .