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排序方式: 共有1038条查询结果,搜索用时 62 毫秒
31.
Junwei Zhang Bu-Sung Lee Xueyan Tang Chai-Kiat Yeo 《The Journal of supercomputing》2011,56(3):245-269
Data Grid has evolved to be the solution for data-intensive applications, such as High Energy Physics (HEP), astrophysics,
and computational genomics. These applications usually have large input of data to be analyzed and these input data are widely
replicated across Data Grid to improve the performance. The job scheduling performance on traditional computing jobs can be
studied using queuing theory. However, with the addition of data transfer, the job scheduling performance is too complex to
be modeled. In this research, we study the impact of data transfer on the performance of job scheduling in the Data Grid environment.
We have proposed a parallel downloading system that supports replicating data fragments and parallel downloading of replicated
data fragments, to improve the job scheduling performance. The performance of the parallel downloading system is compared
with non-parallel downloading system, using three scheduling heuristics: Shortest Turnaround Time (STT), Least Relative Load
(LRL) and Data Present (DP). Our simulation results show that the proposed parallel download approach greatly improves the
Data Grid performance for all three scheduling algorithms, in terms of the geometric mean of job turnaround time. The advantage
of parallel downloading system is most evident when the Data Grid has relatively low network bandwidth and relatively high
computing power. 相似文献
32.
In this paper, we investigate the mean square exponential synchronization of stochastic nonlinear complex dynamical networks with or without communication delays. A new self‐triggered mechanism is proposed to reduce the amount of communication while preserving the desired system's performance. Under this mechanism, the next sampling instant is dynamically determined by the latest transmitted state rather than the online detection of the event‐triggered condition. Meanwhile, we show that the inter‐execution time of self‐triggered mechanism is bounded by a strictly positive constant, and the maximal allowable delay of the underlying system is given. A simulation is provided to illustrate the effectiveness of the proposed self‐triggered scenario. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
33.
Potential Clogging and Dissolution Effects During Artificial Recharge of Groundwater Using Potable Water 总被引:1,自引:0,他引:1
To avoid the water quality deterioration that are caused by artificial recharge (AR) of groundwater, potable drinking water has been used as one of the source water for AR to control the side effects caused by the over-exploitation of groundwater. Chemical clogging problems can still be caused by certain chemical components, especially Fe and Al, and a lower concentration of these elements can cause a notable decrease in hydraulic conductivity at the top layer of the infiltration medium. Some components in AR source water can be obstructed by the clogging layer, leading to a change in water quality. The accumulation of total suspended solids (TSS) at the clogging layer can cause physical clogging and worsen the degree of chemical clogging. Although clogging and the related change in water quality were the dominant issues that affect the infiltration rate and health risks during the AR process, the dissolution of the aquifer matrix should also be taken into account. This dissolution contributed to not only the hydraulic conductivity of the infiltration medium but also the potential change in water quality during the aquifer recharge, storage and recovery processes. 相似文献
34.
中国特色装备文化是我军进行信息化装备建设的文化导向,加强中国特色装备文化建设对于推动我军装备发展、军队信息化转型以及国防和军队建设都起到积极的作用。重点论述了中国特色装备文化的基本特征,中国特色装备文化建设的内容以及实现途径,为中国特色装备文化的发展提出思路。 相似文献
35.
This paper deals with the problem of optimization of job sequence in a two-machine flow shop problem in the presence of uncertainty.
It is assumed that the processing times of jobs on the machines are described by triangular fuzzy sets. A new optimization
algorithm based on Johnson”s algorithm for deterministic processing times and on an improvement of McCahon and Lee”s algorithm
is developed and presented. In order to compare fuzzy processing times, McCahon and Lee use mean values of their corresponding
fuzzy sets. It is shown that this approach cannot fully explore possible relationships between fuzzy sets. In order to overcome
this drawback we consider different fuzzy sets determined by λ-cuts of the fuzzy processing times. Extensive experiments show
that the new algorithm gives better solutions with respect to makespan than existing McCahon and Lee's algorithm. 相似文献
36.
37.
38.
Dynamic Web contents are generated by running application programs on base data which often change frequently. Geographically replicating the applications that construct these contents (including the programs and the related data they access) is an effective approach to improve their access latency. To maintain the freshness of an object replica, the new version of the object either has to be fetched from remote servers or be reconstructed locally when the origin copy is updated. We present a theoretical study on geographical replication of dynamic Web contents with the objective of minimizing the consistency management costs in terms of update transfers and object reconstruction. The dependencies among dynamic objects and base data are modeled as a directed acyclic graph. We formulate the minimum cost replication problem under a flat framework of update delivery. The problem is solved by first transforming it into a minimum cut problem in a flow network. A polynomial-time algorithm is then proposed to compute the optimal replication strategy which designates where each object should be replicated and how to keep the replicas up-to-date. 相似文献
39.
汽轮发电机转子外伸端质量不平衡引起的振动分析 总被引:8,自引:0,他引:8
讨论了汽轮发电机转子外伸端质量不平衡产生的振动特点及其诊断方法,结合现场分析处理实例,阐明发电机转子外伸端质量不平衡产生的振动类似于主跨转子三阶不平衡引起的振动特性,但有时发电机转子两轴承处也会产生明显的反相振动分量。对于外伸端质量不平衡的识别,应根据主跨转子的振型分离情况、转子动力学知识及现场经验综合判断。 相似文献
40.
GAO Shi MA Qingjie CUI Qu LIU Lin ZHOU Xueyan JIA Bing CHEN Zuowei ZHANG Haishan 《核技术(英文版)》2013,(2):36-40
The 99mTc-3PRGD2 targeted SPECT/CT scanning was of significance in detecting differentiated glioma.In this work,the diagnostic value of 99mTc-3PRGD2 scintigraphy in brain glioma was evaluated by the ten clinically verified brain glioma patients after obtaining informed consent.The patients first accepted X-ray imaging to localize the detecting regions before administrating with 99mTc-3PRGD2 at a mean radioactivity of 849±115 MBq via single intravenous bolus injection 2 h prior to SPECT/CT imaging.Tumor samples for detectingαvβ3 were collected by surgical operations two weeks after the scintigraphy.The results of CT and SPECT scanning were merged and compared.The correlation between tumor occupation(T/N ratio) andαvβ3 expression level were analyzed.The T/N ratios in brain glioma were proportionally correlated to av(33 positive cell percentage(R2=0.9253,p<0.05).This study primarily evaluated the clinical application of 99mTc-3PRGD2 SPECT scintigraphy on brain glioma.The more pathological types and detecting strategies covering a large amount of samples would aid to clarify the potentials. 相似文献