Emphasizing the rank positions in a distance-based aggregation procedure

This paper deals with the problem of aggregating individual preferences in order to obtain a social order. In particular, a preference aggregation procedure is proposed for those cases in which the decision-makers express their preferences by means of a ranking of alternatives. Among the most commonly applied methods for this purpose are those based on distance measures between individual and collective preferences, which look for the solution that minimizes the disagreement across decision-makers. This class of procedures may include weighting factors in order to emphasize the relative importance of the individuals. In the model proposed here, a weighted disagreement function that computes the differences between alternatives differentiating the rank positions of the alternatives is developed. The proposed disagreement function weighs the differences between orders depending on the ordinal position that the alternative occupies.     

Realization and synthesis of reversible functions

Reversible circuits play an important role in quantum computing. This paper studies the realization problem of reversible circuits. For any n-bit reversible function, we present a constructive synthesis algorithm. Given any n-bit reversible function, there are N distinct input patterns different from their corresponding outputs, where N≤2ⁿ, and the other (2ⁿ−N) input patterns will be the same as their outputs. We show that this circuit can be synthesized by at most 2n⋅N ‘(n−1)’-CNOT gates and 4n²⋅N NOT gates. The time and space complexities of the algorithm are Ω(n⋅4ⁿ) and Ω(n⋅2ⁿ), respectively. The computational complexity of our synthesis algorithm is exponentially lower than that of breadth-first search based synthesis algorithms.     

一种基于双线性对的群密钥管理方案

现有群密钥管理方案大都基于GDH(Group key Management Based on Diffi}Hellman)密钥交互协议,该协议限制了子树规模。针对这一问题,提出一种基于双线性对的群密胡管理方案(13PGKM, Group Kcy Managcmcnt based on I3ifinear Pairing),该方案在保证安全的前提下可扩大密钥树中子树的规模,以支持更大规模的网络,同时可使计算操作减少一半,以提高群密钥管理操作的效率。     

安全群组通信在远程教育系统中的应用

近年来,随着远程教育的发展,远程教育的通信安全成为远程教育网络安全体系的研究热点。而构建于群组通信系统之上的安全群组通信系统(SGCS),不仅可提供可靠的、顺序的消息传送和小组成员关系服务,还能为成员间消息的传输提供安全机制。针对远程教育通信的特点,将SGCS和流媒体传输技术融合后应用于远程教育通信中,构建了一个远程流媒体课堂系统。     

Global Optimization Based on Heuristic Self-Organization: The Discrete Case

Application of the heuristic self-organization method (or the so-called Group Method of Data Handling) to the solution of discrete optimization problems is considered. Convergence by probability of the self-organization process to a global optimization point is proved. Some examples of numerical experiments are presented.     

Electronic Meeting Support for Councils

City councils hold meetings several times a week. There is a need for computer support at certain meetings. This paper examines the potential for group support systems for use in city council meetings and shows in what ways they can be helpful in pre-meeting and post-meeting activities. The study is based on 17 computer-supported city council meetings, carried out in Stuttgart, Kornwestheim and other cities as part of the Cuparla Project between 1996 and 1998. Three of these meetings are described in the paper as brief case studies. Following this, all 17 meeting sequences are evaluated and analysed. Guidelines have been developed from the results of the study for the introduction of group support systems in city council meetings.     

基于团队机制的高可用性分布式系统的研究与实现

基于分布式环境的高可用系统是采用服务器冗余技术提高的可用性。本文针对分布式环境Ｃｏｒｂａ,给出了基于团队机制的高可用分布式系统的方案,结构和实现,并对这一方案的性能进行了分析和评价。     

Group awareness and self-presentation in computer-supported information exchange

A common challenge in many situations of computer-supported collaborative learning is increasing the willingness of those involved to share their knowledge with other group members. As a prototypical situation of computer-supported information exchange, a shared-database setting was chosen for the current study. This information-exchange situation represented a social dilemma: while the contribution of information to a shared database induced costs and provided no benefit for the individual, the entire group suffered when all members decided to withhold information. In order to alleviate the information-exchange dilemma, a group-awareness tool was employed. It was hypothesized that participants would use group awareness for self-presentational purposes. For the examination of this assumption, the personality variable ‘protective self-presentation’ (PSP) was measured. An interaction effect of group awareness and PSP was found: when an awareness tool provided information concerning the contribution behavior of each individual, this tool was used as a self-presentation opportunity. In order to understand this effect in more detail, single items of the PSP-scale were analyzed.     

Distributed key management for dynamic groups in MANETs

Most existing solutions to group security in Mobile Ad Hoc Networks (MANETs) rely on a multicast Core Based Tree (CBT) for key distribution. Such solutions, although suitable for systems with low mobility and static characteristics, are unsuitable for dynamic and sparse groups with changing neighborhoods. In this paper, we propose an entirely decentralized key generation mechanism, employing a central trusted entity only during initialization. Using our approach, keys can be established between group members with absolutely no prior communication. The solution relies on threshold cryptography and introduces a novel concept of Node-Group-Key (NGK) mapping. We have provided an extensive analytical model for the computations involved and communication costs and have also provided a lie detection mechanism. Simulation results show appreciable performance improvement and enhanced robustness.     

典型产业网络的组织结构分析

产业网络是一种新型的组织协调方式。是产业组织的创新。随着经济的不断发展,产业网络显现了不同的形态特征和发展趋势。本文在网络理论分析的基础上,从主体、行为、资源三个网络要素出发,构楚了产业网络的组织结构分析框架。在此基础上,本文在诸多产业网络的形态中选取了四种较为典型的产业网络进行组织结构分析,分别是虚拟企业、战略联盟、企业集团和产业集群。最后,本文对四种产业网络的组织结构进行了比较。