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A novel network model of multiple source fountain coding is developed and a novel class of generic multiple source fountain codes with unequal error protection(UEP)property is proposed.The And–Or tree analysis technique is generalized to analyze the asymptotic performance of the proposed codes and a joint optimization method employing both linear and nonlinear programs is developed to optimize the degree distributions.Furthermore,we propose three basic methods to achieve UEP property and the performance of each method is discussed.We employ these analytical results and optimization method to design and discuss several UEP codes with two and four sources for different application scenarios.Simulation results verify that the proposed codes can be applied to the networks with any number of sources and can provide strong UEP property in various ways based on the proposed three basic methods. 相似文献
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Juan Li XiaoFei Shi Feng Gao LuQi Liu Rui Chen ChunYing Chen Zhong Zhang 《中国科学:技术科学(英文版)》2014,57(2):239-243
In this study,the size distribution of atmospheric aerosol in Beijing was monitored by the scanning mobility particle sizer spectrometer and the optical particle sizer.The size of particles in atmospheric aerosol was primarily distributed in the range of less than 1 m.It showed different changes with the mass concentrations of particulate matters with an aerodynamic diameter of 2.5 m(PM2.5)for different sizes of fine particles.The amount of ultrafine particles(less than about 60 nm)decreased while the larger ones(60 nm)increased along with the mass concentration of PM2.5 in atmospheric aerosol.This was because of the formation of the secondary atmospheric aerosol.The polylactic acid(PLA)nanofibers were prepared for filtering the aerosol by electrospinning.PLA nanofiber mats were used as the middle layer to design the composite filter membranes.Atmospheric aerosol was used as dust source in the filtration test.The results showed that the filtration efficiency of the composite filter media increased along with the thickness of nanofiber mats,which was controlled by the collection time during electrospinning.Filtration efficiency can be improved obviously by compositing with a thin layer of nanofibers. 相似文献
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主要研究了不同Ce中间合金对A356铝合金的细化变质的效果,结果表明:Al-10Ce和Al-4Ti-4Ce-B中间合金对A356合金具有较好的细化变质效果,Al-5Sr-5Ce中间合金对A356的细化变质效果不够理想,而Al-10Sr中间合金的添加对Al-4Ti-4Ce-B中间合金的细化变质具有促进作用。本文还进行了Ce对A356合金细化变质机理的探讨。 相似文献
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发明一种技术图样表达式.它用英文字母表示图形种类和尺寸要素,并用算术符号等字符表示图形和尺寸相互间的关系.用技术图样表达式可同时表示出图样的形状、大小、定位和公差、粗糙度等技术数据.图样表达式可作技术制图的尺寸标注,使图样大为简化;作计算机传输的信息,使计算机制图更为简易. 相似文献
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宣钢7#高炉是一座450M^3中型高炉,年产生铁约55万多吨。本文介绍的就是宣钢7#高炉的自动控制系统,该自动化系统采用ABB公司的Industrial IT工业集散过程控制系统(DCS)。该系统控制稳定、可靠、故障率低。将先进控制思想、现代通讯技术和自动化技术的最新发展集于一身。 相似文献
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LIAO XiaoFei LI He JIN Hai HOU HaiXiang JIANG Yue & LIU HaiKun Services Computing Technology System Lab Cluster Grid Computing Lab School of Computer Science Technology Huazhong University of Science Technology Wuhan China 《中国科学:信息科学(英文版)》2011,(6):1104-1118
Desktop virtualization is a very hot concept in both industry and academic communities. Since virtualized desktop system is based on multiple virtual machines (VM), it is necessary to design a distributed storage system to manage the VM images. In this paper, we design a distributed storage system, VMStore, by taking into account three important characteristics: high performance VM snapshot, booting optimization from multiple images and redundancy removal of images data. We adopt a direct index structure of... 相似文献
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基于网格监控系统的动态监控间隔的研究 总被引:2,自引:0,他引:2
网格环境是由很多元素构成的高度复杂的分布式计算环境。对于网格来说,监控其中每个计算节点的状态是至关重要的。然而频繁地监控资源的状态信息会增加系统的负担。本文提出一种动态调整监控间隔的方法, 来降低监控服务所需的花费,并利用动态监控间隔来准确地获取监控事件,最后通过在网格环境下进行实验,对该方法做出客观的评价。 相似文献
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介绍接地电阻测试的基本原理,设计了符合IEC61010标准的由工业PC控制的接地电阻测试系统。系统由程控电源、测试回路、信号采样、调理电路和数据采集接口卡等部分组成。实验数据表明系统工作稳定,数据重复精度高。 相似文献