Characterizing the computational power of energy-based P systems

We investigate the computational power of energy-based P systems, a model of membrane systems, where a fixed amount of energy is associated with each object and the rules transform single objects by adding or removing energy from them. We answer the recently proposed open questions about the power of such systems without priorities associated with the rules, for both sequential and maximally parallel modes. We also conjecture that deterministic energy-based P systems are not computationally complete.     

Unexpected universality results for three classes of P systems with symport/antiport

Symport and antiport are biological ways of transporting molecules through membranesin ``collaborating' pairs; in the case of symport the two molecules pass in the same direction, in the case of antiport the two molecules pass in opposite directions. Here we first survey the results about the computing power of membrane systems (P systems) using only symport/antiport rules (hence these systems compute by communication only), then we consider a recently introduced, way of defining the result of a computation in a membrane system: looking for the trace of certain objects in their movement through membranes. Rather unexpected, in this way we get characterizations of recursively enumerable languages by means of membrane systems with symport/antiport which work with multisets of objects (note the qualitative difference between the data structure used by computations – multisets: no ordering– and the data structure of the output – strings: linear ordering). A similar remark holds true for the case of analysing P systems, which work in an automata-like manner: the sequence of certain distinguished objects taken from the environment during acomputation is the string recognized by the computation. We also survey universality results from this area, with sketched proofs. Some open problems are also formulated. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characterizing Grids: Attributes, Definitions, and Formalisms

Grid systems and technologies have evolved over nearly a decade; yet, there is still no widely accepted definition for Grids. In particular, the essential attributes that distinguish Grids from other distributed computing environments have not been articulated. Most approaches to definition adopt a static view and consider only the properties and components of, or the applications supported by, Grids. The definition proposed in this paper is based on the runtime semantics of distributed systems. Rather than attempt to simply compare static characteristics of Grids and other distributed computing environments, this paper analyzes operational differences, from the viewpoint of an application executing in both environments. Our definition is expressed formally as an Abstract State Machine that facilitates the analysis of existing Grid systems or the design of new ones with rigor and precision. This new, semantical approach proposes an alternative to the currently accepted models for determining whether or not a distributed system is a Grid.     

基于Agent的分布式模型形式化语义描述

为解决分布式系统构建过程中系统组合和语义验证等方面的问题,基于范畴理论和进程代数,为基于Agent的分布式系统模型提出了一种形式化的语义描述框架。范畴图表用于描述整个系统的结构模型,态射用来表示系统各组成部分之间的交互和协作机制。在此基础上,对Agent规范的描述、组合、精化以及迁移过程中的语义保持问题进行了探讨。应用研究表明,该框架适用于分布式系统模型的描述和构建,有助于分析系统分解和组合的正确性。     

About P systems with symport/antiport

It is proved that four membranes suffice to a variant of P systems with symport/antiport with maximal parallelism to generate all recursively enumerable sets of numbers. P systems with symport/antiport without maximal parallelism are also studied, considering two termination criteria.     

自然语言处理技术在药物专利检索中的应用研究

本文研究了自然语言处理技术在药物专利检索中的应用,开发出一套翻译软件,能够将药物专利中对族性变量的文本描述半自动化地转化为符合规则的GSCCT格式,为准确、高效地建立药物专利检索数据库打下了基础。     

基于大规模廉价计算平台的海量数据处理系统的研究*

提出一种基于大规模廉价计算平台的海量数据处理模型,吸取了Map/Reduce计算模式和大规模分布式数据存储机制Bigtable的基本思想,实现了以数据为中心的计算密集型的经济性超级计算系统平台。系统选择电信部门的大规模业务数据为分析对象,对电信通话和数据业务的大规模数据集进行处理,从而向运营商和普通用户提供有价值的数据分析服务。该平台适用于其他多种海量数据的分布式处理,为其他的各种应用提供了一个具有良好参考价值的示范。     

基于细胞膜演算的Web服务事务处理形式化描述与验证

采用细胞膜演算具体分析了当前比较主流的Web服务中原子事务协调协议WS-AT．针对WS-AT协议采用简单的状态转换表和转换图,无法描述协调者和多个参与者的复杂协调活动,采用细胞膜演算给出了其形式化描述,用于规范协调者和参与者的活动,并分析了该协议的活性和安全性,得到了38187个状态．模型检验的实验结果表明,该协议满足稳定性、一致性和非平凡性,而不满足非阻塞性．进而,分析出注册和协调协议混在一起是其不满足非阻塞性的原因．     

志愿者计算模型的研究进展

志愿者计算模型由于可以高效的聚集和利用在Internet上闲散的大规模计算资源,使得人们对高性能计算的研究与实现比集群系统更加廉价和容易,近年来已在工程和科学计算中显示其越来越重要的作用.在构造志愿者计算环境的过程中,志愿者计算网络的拓扑架构、任务的调度模型、应用的编程模型、数据的传输协议、应用的扩充研究等都是研究的关键技术点.本文分析志愿者计算的基本概况,综述了目前的志愿者计算项目在关键技术点上的研究进展,并对其今后的若干研究方向进行了展望.     

基于网格计算技术的电力系统分布式并行计算——底层平台设计与实现

文章提出了基于网格计算来实现电力系统分布式并行计算的方案。主要涉及计算池(ComputingPool)的设计、资源的管理与动态分配,以及图论分割和稀疏数值计算库的设计和实现等。文章首先介绍了网格计算应用于电力系统分布式并行计算的概念,在此基础上,分析了基于GlobusR网格计算开发平台实现的以上功能模块。最后对测试平台和测试结果进行了简要的介绍。     

Parallel four‐dimensional Haralick texture analysis for disk‐resident image datasets

Texture analysis is one possible method of detecting features in biomedical images. During texture analysis, texture‐related information is found by examining local variations in image brightness. Four‐dimensional (4D) Haralick texture analysis is a method that extracts local variations along space and time dimensions and represents them as a collection of 14 statistical parameters. However, application of the 4D Haralick method on large time‐dependent image datasets is hindered by data retrieval, computation, and memory requirements. This paper describes a parallel implementation using a distributed component‐based framework of 4D Haralick texture analysis on PC clusters. The experimental performance results show that good performance can be achieved for this application via combined use of task‐ and data‐parallelism. In addition, we show that our 4D texture analysis implementation can be used to classify imaged tissues. Copyright © 2006 John Wiley & Sons, Ltd.     

ODP系统企业观点的形式化描述

ＯＤＰ系统的企业观点反映了开放分布式系统对象之间的合作关系，本文以模态逻辑为工具来讨论企业观点下ＯＤＰ系统的形式化描述方法，通过在合作的系统对象和模态逻辑的可通界关系之间建立联系，并使用多值逻辑来计算模态命题真值的方法来形式化地表述系统对象之间的合作关系，并用这种方法建立了一组共同体的存在性约束规则。     

高实时要求的嵌入式智能计算云平台设计

智能云计算是下一代智能作战装备的发展趋势,本文针对军事应用场景下的高实时性要求,介绍一种嵌入式智能云计算平台.该系统基于ARM+DSP+FPGA架构,采用MapReduce技术,可实现大数据智能计算方法在典型军事应用场景下的应用.     

基于虚拟化与分布式技术的存储系统

介绍了一套基于云计算(cloud computing)技术的数据应用平台系统设计方案。该系统由多组服务器集群组成,可提供数据存储、备份和并行运算服务。并可采用虚拟化应用端与分布式(Hadoop)技术相结合的方式为用户提供高容量和异构应用存储系统,以便结合iSCSI协议在硬件层获得更灵活的部署。     

CEStream:一种复杂事件流处理语言

复杂事件处理是支持大数据处理的流式计算平台的核心技术之一。CEStream语言作为一种新型的事件流处理语言,支持分布式环境下的复杂事件处理。该语言以XML等层次化数据为数据模型,为复杂事件检测提供了一种正规树模式匹配功能,并且支持结构连接和正规式匹配。同时,针对分布式的多个事件流,其能够将各个事件源模式匹配的结果按照时间顺序再一次进行正规式模式匹配,满足多源组合型复杂事件的检测需求,具有较强的事件处理能力。为了实现CEStream语言,研制了一个基于流数据处理集群和远端查询代理的执行引擎系统。该系统通过远程查询代理实现基于正规树模式的事件检测,通过流处理集群完成多源组合型复杂事件处理。实验表明,该系统实现了CEStream语言,有效地限制了各个节点之间的通信量,充分利用了集群的计算能力,整体性能能够满足应用需求。     

云计算中隐私需求的建模与一致性检测

云计算中应用分层、服务外包以及数据的分布存储等特性引发了隐私保护的新挑战.如何刻画不同服务提供者的隐私需求,并保证不同参与方隐私需求在全局应用上一致无冲突是云计算隐私保护的一个核心问题.在对隐私需求的分类和建模目标系统分析后,提出了一种综合考虑了数据、角色和目的的层次结构,并支持时序约束表达的声明式隐私需求描述语言DPPL.为验证不同隐私需求间的一致性,给出了该语言的形式化语义及对应的形式化建模算法.考虑到传统形式化验证由于空间爆炸而带来的实用性限制,进一步结合隐私活动的特征提出了隐私需求模型的约简方法.最后,通过实例分析和原型工具检验了所提出方法的可行性,并对于该方法目前尚存在的限制和未来工作进行了讨论.     

DNA计算的基本代数原理(一)

在文中,通过引进M-粘连代数、M-剪切代数与M-重组代数等概念,达到了使与标志集M相关联的DNA计算可按所引进代数中给出的代数定律来推演的目的.进而研究了这些代数的一系列性质,得到了许多有价值的结果.它们对DNA计算的理论与应用研究必将带来极大的便利.     

面向对象语言并行化中的调用局部化优化

该文提出了一种将调用局部化技术应用于并行环境下面向对象语言的方法，文中详细讨论了该技术的适用条件以及如何通过该方法减少循环中的远程过程调用开销，该优化技术产首先将循环分离成多个包含有远程调用的循环，再将分离后的循环分离给循环中对象所在的处理器，最后，化简迭代空间，并且用消息传递来传输数据，这种优化对象分布和循环并行化之后进行，将函数调用局部化于处理器，通过这种优化，可以进一步挖掘循环中的任务并行性，降低计算复杂度，减少函数调用开销，尤其适合面向对象语言中对循环里小函数的优化，该技术已经在作者设计的Java自动并行化编译器JAPS－Ⅱ中实现，在实验中，利用这种优化技术得到了超线性性加速比。     

Optimal control of infinite horizon partially observable decision processes modelled as generators of probabilistic regular languages

Decision processes with incomplete state feedback have been traditionally modelled as partially observable Markov decision processes. In this article, we present an alternative formulation based on probabilistic regular languages. The proposed approach generalises the recently reported work on language measure theoretic optimal control for perfectly observable situations and shows that such a framework is far more computationally tractable to the classical alternative. In particular, we show that the infinite horizon decision problem under partial observation, modelled in the proposed framework, is λ-approximable and, in general, is not harder to solve compared to the fully observable case. The approach is illustrated via two simple examples.