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21.
22.
结构化P2P网络研究 总被引:1,自引:0,他引:1
结构化P2P系统采用支持分布式哈希表(DHT)的路由算法,根据精确关键字进行对象的定位与发现。本文介绍了两种结构化P2P系统:CAN和Chord系统。重点分析了这两种结构化P2P系统的构建和路由算法以及对等节点加入和离开P2P系统的过程,并详细讨论了CAN和Chord的改进方案,最后指出了结构化P2P系统所面临的问题与不足。 相似文献
23.
WANG Xiu-li TU Jiang-ping CHEN Chang-pin ZHANG Xiao-bin ZHAO Xin-bing 《Journal of Zhejiang University. Science. B》2005,(3)
Mg2Ni0.8Cr0.2-x wt.% CoO/Al2O3 (x=0.5, 1, 2 and 3) composites were prepared by mechanically milling sintered Mg2Ni0.8Cr0.2 alloy and CoO/Al2O3 compound for 45 h. The addition of CoO/Al2O3 compound resulted in the good kinetics properties of hydriding/dehydriding reaction of the composites. The composite with 1.0 wt.% CoO/Al2O3 catalyst could reach the maximum hydrogen absorption capacity (2.9 wt.%) within 5 min at 393 K under H2 pressure of 4 MPa, and can desorb rapidly at 493 K. The decomposition and synthesis of hydrogen molecule on Mg2Ni0.8Cr0.2 alloy surface was promoted by addition of CoO/Al2O3 catalyst. In addition, the formation of metallic Ni particles, strain and defects during the ball milling process also resulted in the improved hydrogenation performance of Mg2Ni-based alloys. 相似文献
24.
分析了我国鲜活植物产品贮藏保鲜与专业技术人才培养的现状和存在的问题,提出了开办农产品贮藏工程与技术专业,培养具有现代生物学、工程学、信息学及贸易学知识和技术,具有国际观的现代复合型农产品贮藏保鲜专门人才的建议. 相似文献
25.
介绍了一种以TI公司的TMS320LF2407A DSP芯片为核心的实时数据采集存储系统设计方案.该系统通过外接12位AD转换器AD7858来提高DSP采样精度,实时采集病人的心电数据,通过数字滤波处理后可以真实反映病人的心脏健康状况,借助串口电路建立与上位机的通讯.相对于采用PC机和单片机设计的系统,该系统具有功耗小、成本低、实时性强等优点. 相似文献
26.
本文对心理词汇、外语心理词汇、二语心理词汇、双语心理词汇所涉及到的语言与思维关系问题进行了较为深入的分析、阐释和讨论,明确指出:1)在语言习得和外语学习过程中,逻辑思维和形象思维两套系统会因信息输入途径的不同而各自、相继或同时参与着信息加工;2)两种思维系统所参与的信息加工,会以"词条或概念群组"的形式加以储存;3)提出了外语学习信息加工心理词库的假说;4)并对定位论和总体论以及各种类型心理词汇的分类、概念及其信息输入、储存、激活等问题分别进行了简明扼要地阐述、分析和讨论;在此基础上,提出了"人脑信息加工神经网络化体系论"假说。 相似文献
27.
陈仕洲 《韩山师范学院学报》2011,(6):1-7
利用Mawhin重合度理论,研究了一类具有分布时滞的高阶P—Laplacian中立型微分方程,获得了其周期解存在性的一些新结果. 相似文献
28.
File semantic has proven effective in optimizing large scale distributed file system. As a consequence of the elaborate and
rich I/O interfaces between upper layer applications and file systems, file system can provide useful and insightful information
about semantic. Hence, file semantic mining has become an increasingly important practice in both engineering and research
community. Unfortunately, it is a challenge to exploit file semantic knowledge because a variety of factors could affect this
information exploration process. Even worse, the challenges are exacerbated due to the intricate interdependency between these
factors, and make it difficult to fully exploit the potentially important correlation among various semantic knowledges. This
article proposes a file access correlation miming and evaluation reference (FARMER) model, where file is treated as a multivariate
vector space, and each item within the vector corresponds a separate factor of the given file. The selection of factor depends
on the application, examples of factors are file path, creator and executing program. If one particular factor occurs in both
files, its value is non-zero. It is clear that the extent of inter-file relationships can be measured based on the likeness
of their factor values in the semantic vectors. Benefit from this model, FARMER represents files as structured vectors of
identifiers, and basic vector operations can be leveraged to quantify file correlation between two file vectors. FARMER model
leverages linear regression model to estimate the strength of the relationship between file correlation and a set of influencing
factors so that the “bad knowledge” can be filtered out. To demonstrate the ability of new FARMER model, FARMER is incorporated
into a real large-scale object-based storage system as a case study to dynamically infer file correlations. In addition FARMER-enabled
optimize service for metadata prefetching algorithm and object data layout algorithm is implemented. Experimental results
show that is FARMER-enabled prefetching algorithm is shown to reduce the metadata operations latency by approximately 30%–40%
when compared to a state-of-the-art metadata prefetching algorithm and a commonly used replacement policy. 相似文献
29.
As a parallel programming model, Map-Reduce is used for distributed computing of massive data. Map-Reduce model encapsulates
the details of parallel implementation, fault-tolerant processing, local computing and load balancing, etc., provides a simple but powerful interface. In case of having no clear idea about distributed and parallel programming, this
interface can be utilized to save development time. This paper introduces the method of using Hadoop, the open-source Map-Reduce
software platform, to combine PCs to carry out scalable parallel computing. Our experiment using 12 PCs to compute N-body problem based on Map-Reduce model shows that we can get a 9.8x speedup ratio. This work indicates that the Map-Reduce can be applied in scalable parallel computing. 相似文献
30.
通过对2004年至2005年武汉4个主要钢材仓储货场的考察,结合武钢集团销售模式和钢铁物流的特点,剖析了货场运作中的弊病,并提出了三步走的改造方案。最后对武汉钢铁流通产业的未来格局作了分析展望。 相似文献