共查询到19条相似文献，搜索用时 265 毫秒
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1 Introduction Large and complex engineering problems often needmuch computation ti me and storage to run on ordinaryuniprocessor computers . Even if they can be solved ,powerful computation capability is required to obtainaccurate and reliable results within reasonable ti me .Parallel computing can meet requirements of high per-formance computing[1].Various types of parallel hard-ware architectures have been developed and parallelalgorithms adapted to these hardware architecturesproposed[2 ,3… 相似文献
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1 Introduction One class of applications , such as power networkscheduling, intelligent traffic and real-ti me monitor-ing,demand that distributed databases are able to pro-cess theti ming constraints of data and transactions andprovide ti mely and correct results ,i.e. distributedreal-ti me database systems are required .In general ,adistributed real-ti me database system(DRTDBS) is thedistributed database system within which transactionsand data have ti ming constraints and system correct-… 相似文献
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1IntroductionRecent advances in wireless communication,digitallibrary,distributed multi media,massive storage,andmobile computing technologies are sti mulating the de-velopment of mobile multi media digital library systems(M2DLS)that allow mobile clients to access multi me-dia material anywhere and anyti me over a cellular ra-dio network[1,2].In M2DLS,multi media objects,ingeneral,can be composed of multiple media streamssuch as audio and video,whose retrieval must proceedso as to not only … 相似文献
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1IntroductionSerpentine used as inorganic material inindustry hasbeeninvestigated for many years[1-3].But there are noreports on serpentine cat’s eye owing to its rarity.During our recent field investigation in Sichuan Prov-ince,southwest of China,for the first ti me we discov-ered the rare serpentine cat’s eye with well-growntex-ture and,if properly polished,a vivid cat eye effect(see Fig.1).Weng,et al.[4]also reported the newdiscovery of nephrite cat’s eyes inthis region.Serpen-tine can… 相似文献
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The lifeti me maintenance of a bridge can comprise amuch greater portion of the total lifeti me cost than theoriginal cost of construction because of deterioration.An opti mal maintenance programis the key to makingappropriate decisions to mini mize cost and maintain anappropriate level of safety.Life-cycle cost is a usefulconcept in reducing the overall cost and achieving anappropriate maintenance plan[1,2].It is difficult tomake a reliable esti mate of thelifeti me costs whenthefuture of the… 相似文献
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Dynamic distribution model is one of the best schemes for parallel volume rendering. However, in homogeneous cluster system, since the granularity is traditionally identical, all processors communicate almost simultaneously and computation load may lose balance. Due to problems above, a dynamic distribution model with prime granularity for parallel computing is presented. Granularities of each processor are relatively prime, and related theories are introduced, A high parallel performance can be achieved by minimizing network competition and using a load balancing strategy that ensures all processors finish almost simultaneously, Based on Master-Slave-Gleaner （ MSG） scheme, the parallel Splatting Algorithm for volume rendering is used to test the model on IBM Cluster 1350 system. The experimental results show that the model can bring a considerable improvement in performance, including computation efficiency, total execution time, speed, and load balancing. 相似文献
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MOTIVATION The calculus of Mobile Ambients (MA) (Cardelli and Gordon, 1998) was proposed to model the mobile computation based upon the notion of ambient, a bounded location where computation takes place. It can also perform movements and carry mul-tiple processes and nested ambients within it: Primi-tive “in” and “out” allows the ambient to cross the computation boundary, and primitive “open” allows the boundary to dissolve and then to unleash the in-ternal processes. Later on, s… 相似文献
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This paper proposes a design optimization method for the multi-objective orbit design of earth observation satellites, for which the optimality of orbit performance indices with different units, such as: total coverage time, the frequency of coverage, average time per coverage and maximum coverage gap, etc. is required simultaneously. By introducing index normalization method to convert performance indices into dimensionless variables within the range of [0, 1], a design optimization method based on the principal component analysis and cluster analysis is proposed, which consists of index normalization method, principal component analysis, multiple-level cluster analysis and weighted evaluation method. The results of orbit optimization for earth observation satellites show that the optimal orbit can be obtained by using the proposed method. The principal component analysis can reduce the total number of indices with a non-independent relationship to save computing time. Similarly, the multiple-level cluster analysis with parallel computing could save computing time. 相似文献
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Multi-proxy signature schemes allow the original signer to delegate his/her signing power to n proxy signers such that all proxy signers must corporately generate a valid proxy signature on behalf of the original signer. We first propose a multi-proxy signature scheme based on discrete logarithms and then adapt it to the elliptic curve cryptosystem. With the integration of self-certified public-key systems and the message recovery signature schemes, our proposed schemes have the following advantages： （1） They do not require the signing message to be transmitted, since the verifier can recover it from the signature; （2） The authentication of the public keys, verification of the signature, and recovery of the message can be simultaneously carried out in a single logical step; （3） No certificate is needed for validating the public keys. Further, the elliptic curve variant with short key lengths especially suits the cryptographic applications with limited computing power and storage space, e.g., smart cards. As compared with the previous work that was implemented with the certificate-based public-key systems, the proposed schemes give better performance in terms of communication bandwidth and computation efforts. 相似文献
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1.A friend of mine says to me that his son is only four years old,but can speak English fluently and clearly.Though I don't believe it,that's true.Why?
2.An orange fell to the ground dirtied.If there is no water,how can I clean it and eat it?
3.Neither a plane nor a bird am I,though you can see me in the sky.Full of water,yet not a river or the sea.What do you think I can be?
4.Jim wanted to go into the house.He brought out the key and opened the door.But whatever he did,he couldn't push the door. 相似文献
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付朝江 《福建工程学院学报》2010,8(1)
稀疏矩阵与向量相乘的问题是大规模科学与工程计算的核心部分。考虑在工作站机群上实现大型稀疏矩阵与向量乘的负载平衡,提出了一个快速负载平衡和有效的消息传递技术相结合的方法,来缓解计算和节点间通信。并且通过I/O延迟隐藏和整体负载平衡使I/O开销能有效地分摊。数值测试表明,该方法具有良好的性能。 相似文献
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基于C-N格式提出了热传导方程区域分解的并行差分方法。该方法在子区域的边界处采用古典显格式计算,在子区域内部使用C-N格式进行求解。对算法进行了稳定性分析,得到稳定性条件为r〈1。 相似文献
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ZHUJialin ZHANGTaiping 《重庆大学学报(英文版)》2002,1(1):47-52
A boundary element method based on non-overlapping domain decomposition method to solve the time-dependent diffusion equations is presented.The time-dependent fundamental solution is used in the formulation of boundary integrals and the time integratioin process always restarts from the initial time condition.The process of replacing the interface values,which needs a summation of boundary integrals related to the boundary values at previous time steps can be treated in parallel parallel iterative procedure,Numerical experiments demonstrate that the implementation of the present alogrithm is efficient. 相似文献
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对网格方程组作区域分裂并行计算,应用谱等价胜质讨论了变换在预条件迭代中的作用．将近似LU分解与局部正交化方法相结合构造预处理矩阵,并通过算例证明了这种方法的有效性． 相似文献
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This paper presents a new approach to parallelize 3D lattice Monte Carlo algorithms used in the numerical simulation of polymer on ZiQiang 2000-a cluster of symmetric multiprocessors(SMPs).The combined load for cell and energy calculations over the time step is balanced together to form a single spatial decomposition.Basic aspects and strategies of running Monte Carlo calculations on parallel computers are studied.Different steps involved in porting the software on a parallel architecture based on ZiQiang 2000 running under Linux and MPI are described briefly.It is found that parallelization becomes more advantageous when either the lattice is very large or the model contains many cells and chains. 相似文献
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In this work, two parallel implementation strategies for the numerical simulation of wind flow around buildings were developed
based on a four-processor transputer system. The first parallel strategy is based on the functional decomposition of the problem.
It is easily implementable, but the degree of parallelism is low. In the second strategy, both the functional and the domain
parallelisms of the problem were utilized, so the degree of parallelism is highly increased. Numerical examples indicate that
the parallel speed-ups and efficiencies achievable by the second strategy are significantly greater than those of the first
one.
Project (59478034) supported by Natural Science Foundation of China. 相似文献
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发掘和利用现有串行算法中的并行性,直接将串行算法改造为并行算法,是并行算法设计的最常用方法之一。提出一个基于Huang算法的解一族线性方程组的并行算法,该算法在集群系统环境下,具有较好的灵活性和优越性。算例表明,对病态线性方程组显得特别有效。特别是在时间紧迫、可考虑方案或边值可选较多的情况下,具有可观的快捷高效性。 相似文献