Modeling of Software Partition for Distributed Real-Time Applications

The issue of software partition deals with the process of mapping the given set of logical modules, which reflect the user's point of view, into a set of software tasks, which reflect the software implementor's point of view. It is shown in this paper that the software partitioning problem can be modeled as one that maximizes the efficiency in resource utilization while observing the constraints on CPU throughput, memory space available, maximally allowed task execution time, and the order of module execution. The CPU and memory constraints are implementation dependent. The maximum task execution time constraint is due to considerations on the response time performance. The constraint on module execution order is a logical one, and it is shown to have significant performance impact. It is proven that by employing the module precedence relation, which reflects the sequence of module execution, the order of module execution can be properly maintained during the software partitioning process. And thus the defined tasks can be guaranteed to be completely executable, once properly activated With completely executable tasks, the operating overhead cost and the response time delay can be minimized. The following four module precedence relations are explored: precede, succeed, parallel, and precede as well as succeed. The validity of the selected partitioning criterion of maximizing the resource utilization efficiency is also assessed through simulation experiments. The results of simulation show that performance of the selected criterion is insensitive to the application environment, as well as to the application requirements.     

分布式虚拟环境中区域重叠划分研究

分布式虚拟环境在划分区域后,区域边界附近的化身不能实时交换动态信息。针对这一情况,提出了区域重叠划分方法,通过增加一定的网络负载和多播组数目,来最大限度地保证相邻化身之间实时交换数据。详细分析了区域重叠划分方法,以及实现中的具体问题。     

有效的完全分布式代理签名体制

章提出了基于椭圆曲线密码的完全分布式代理签名体制,极大地提高了代理密钥分布式生成和代理签名分布式生成的效率。     

基于查询空间的分布式文档集合划分算法

合理的文档集合划分能够有效的提高分布式信息检索的效果,本文针对分布式信息检索中的集合划分问题,提出了一种基于查询空间的文档集合划分算法。与传统的基于文档空间的划分算法相比,该算法从一种全新的角度看待和理解文档集合划分问题,给出了一种针对大规模海量信息的文档集合划分解决方案。实验表明该算法在算法效果和算法效率方面都有很大的提高。     

分布式关联规则挖掘中的聚类分区算法

在分布式关联规则挖掘中首先需要解决分布武环境下的聚类分区问题,该文基于CURE的工作原理,提出了D-CURE算法。实验证明,D-CURE算法可以很好地解决分布式环境下聚类分区问题。     

分布式信息检索中文档集合划分问题的评价

分布式信息检索的文档集合划分方案的评价是一个困难的问题,目前还没有良好的评价标准.从文档集合划分问题本身出发,给出了两个划分模型来刻画文档集合划分问题,从而使这两个模型可以作为文档集合划分的有效评价指标.在此基础上,提出了一种类Huffman编码的模型快速求解算法,可以求出在给定查询测试集情况下的最优文档划分方案,该方案可以作为其他文档划分方案的参考.实验表明,两个文档划分模型可以成为有效的文档集合划分评价标准.     

分布式关联规则挖掘中的聚类分区算法

在分布式关联规则挖掘中，首先需要解决分布式环境下的聚类分区问题。该文基于CURE的工作原理，提出了D-CURE算法。实验证明，D-CURE算法可以很好地解决在分布式环境下的聚类分区问题。     

基于链接划分的分布式WEB信息检索

分布式信息检索是面向海量WEB信息检索的一种有效手段.本文采用一种基于链接的聚类方法(LIBCA)来对网页数据进行划分,并采用BloomFilter优化LIBCA算法的计算效率,在检索过程中采用CORI集合选择算法和OKAPI BM25检索算法.基于最近3年的TREC WEB实验数据集,对比集中式检索、基于随机划分的分布式检索,实验结果表明,本文方法在P@10的指标上可达到甚至超过集中式检索的效果.效率方面的实验表明利用BloomFilter的LIBCA算法具有较高的划分效率,适合海量数据的处理.     

A Fully Distributed Proactively Secure Threshold-Multisignature Scheme

Threshold-multisignature schemes combine the properties of threshold group-oriented signature schemes and multisignature schemes to yield a signature scheme that allows a threshold (t) or more group members to collaboratively sign an arbitrary message. In contrast to threshold group signatures, the individual signers do not remain anonymous, but are publicly identifiable from the information contained in the valid threshold-multisignature. The main objective of this paper is to propose such a secure and efficient threshold-multisignature scheme. The paper uniquely defines the fundamental properties of threshold-multisignature schemes and shows that the proposed scheme satisfies these properties and eliminates the latest attacks to which other similar schemes are subject. The efficiency of the proposed scheme is analyzed and shown to be superior to its counterparts. The paper also proposes a discrete logarithm based distributed-key management infrastructure (DKMI), which consists of a round optimal, publicly verifiable, distributed-key generation (DKG) protocol and a one round, publicly verifiable, distributed-key redistribution/ updating (DKRU) protocol. The round optimal DKRU protocol solves a major problem with existing secret redistribution/updating schemes by giving group members a mechanism to identify malicious or faulty share holders in the first round, thus avoiding multiple protocol executions     

Building Distributed Context-Aware Applications

Context-aware applications gather information from sensors about their users and operating environment. Sensor handling is a complicated issue that makes it hard and time-consuming to develop context-aware applications. This paper shows how dynamic discovery protocols can be employed to deal with the physical distribution of sensors and the need to share sensors between many applications. We report on our experiences from building a position-aware application using the dynamic discovery protocol that is part of the Jini software infrastructure for distributed systems.     

一种高拓扑一致性完全分布式节点发现模型

由于缺少集中式服务器的全局管理,节点发现成为基于P2P的大规模分布式虚拟环境(DVE)设计的一个挑战.在满足全局连通性的基础上,通过满足AOI邻居封闭性、邻居封闭性和薄弱区周期关注性这三个不同强弱的拓扑要求来实现系统的局部感知性,提出了一种保证高拓扑一致性的节点发现分析框架.在此框架的基础上,设计了具有高拓扑一致性的完全分布式节点发现模型SimWorld.实验结果表明SimWorld模型的拓扑一致性接近100%.     

Distributed Graph Traversals by Relabelling Systems with Applications

Graph traversals are in the basis of many distributed algorithms. In this paper, we use graph relabelling systems to encode two basic graph traversals which are the broadcast and the convergecast. This encoding allows us to derive formal, modular and simple encoding for many distributed graph algorithms. We illustrate this method by investigating the distributed computation of a breadth-first spanning tree and the distributed computation of a minimum spanning tree. Our formalism allows to focus on the correctness of a distributed algorithm rather than on the implementation and the communication details.     

全同态加密研究动态及其应用概述

随着互联网的发展,尤其是云计算概念的诞生,人们在加密数据搜索与处理等方面的需求日益增加,使得全同态加密变得愈加重要.全同态加密的思想是20世纪70年代Rivest等人首次提出的,如何构造满足全同态性质的体制一直是困扰密码学家的难题,直到2009年Gentry基于理想格提出了第1个全同态加密体制使得该方面的研究取得突破性进展.随后许多密码学家在全同态加密方案的研究上作出了有意义的工作,促进了全同态加密向实用化的发展.对全同态加密的研究动态进行了概要的介绍,包括Gentry提出的第1个全同态加密方案及其优化;基于整数的全同态加密方案;基于LWE问题的全同态加密方案等.随后探讨了全同态加密的一般性应用框架,并以云计算、电子投票、数字水印3个应用为例,介绍了全同态加密的重要应用价值.     

Editorial: Parallel and Distributed Processing with Applications

The Journal of Supercomputing -     

基于分形维度的完全分布式聚类算法

传统的聚类算法通常针对单处理机,当数据资源分别存储在不同节点的计算机时,无法运用传统的聚类算法进行计算。本文提出一种完全分布式聚类算法,通过计算分形维度,利用分布式环境信息广播方式交流多台计算机的运行结果,最终汇集成全局聚类的信息进行聚类。理论分析表明,该算法不仅对分布数据可以很好的聚类而且可以最大限度降低通信成本和延时情况。