排序方式: 共有16条查询结果,搜索用时 15 毫秒
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使用桩腿内切割方式进行导管架平台拆除过程中,需对桩腿进行抽泥作业;清淤泵作为桩腿内抽泥系统的关键设备,其性能直接决定了清淤系统的工作效率.为了获得抽泥系统中清淤泵的最优配置方案,基于熵权-模糊层次分析法对清淤泵的性能进行综合评价.建立清淤泵性能指标评价数学模型,从5种性能相近的清淤泵中获得了最优选型方案.研究结果表明:NSQ100-60-45型清淤泵的综合评价权重最大,性能更适合桩腿内抽泥作业.文章建立的清淤泵性能评价模型具有较高的可靠性,对抽泥系统中清淤泵方案选择具有指导意义. 相似文献
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目的建立应用测汞仪直接测定野生食用菌中总汞含量的测定方法。方法样品经均质器粉碎,称量后,直接进样。样品在催化管内加热分解,在氧气的作用下,汞在齐化管内与金粉反应被捕集下来,形成金汞齐,再经高温使金汞齐分解成汞原子蒸气经载气带入吸收池,在253.7 nm处进行吸收测定。结果测汞仪检测方法线性范围:0.0~1000 ng/L,检出限为0.005 ng/m L,相关系数(R2)优于0.999,相对标准偏差(RSD)小于1.5%,回收率大于99%。结论用此仪器检测的方法无需进行样品前处理、进样量少、方法灵敏度高、精密度好、结果准确可靠、操作简单快速、没有试剂污染、检测速度快和运行成本不高,适用于野生食用菌中总汞的测定。 相似文献
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基于IXP1200的快速报文分类算法的设计与实现 总被引:3,自引:1,他引:3
通过对现有报文分类算法的分析和性能比较,并结合分类规则所具有的特性提出了一种新的基于IXP1200网络处理器的多维报文分类算法,称为PCBNP(packet classification based on network processor),并达到了报文的线速转发.算法除了通过减少分类的规则数和分类的域宽来加快分类的速度外,还采用重定向排序索引、位向量表示匹配规则等技术来加快分类的速度,特别是利用了规则的动态分布规律来确定查找报文字段的顺序,通过先查找“分布最均匀的字段”来达到在所有的字段被查找之前提前找到报文匹配的过滤规则的目的.算法具有高速、多维和可扩展的特性,与现有的算法比较,该算法在综合性能上优于已有的报文分类算法. 相似文献
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A copolyester was characterized to have 91 mol% trimethylene terephthalate unit and 9 mol% ethylene terephthalate unit in a random sequence by using 13C NMR. Differential scanning calorimeter (DSC) was used to investigate the isothermal crystallization kinetics in the temperature range (Tc) from 180 to 207 °C. The melting behavior after isothermal crystallization was studied by using DSC and temperature modulated DSC (TMDSC). The exothermic behavior in the DSC and TMDSC curves gives a direct evidence of recrystallization. No exothermic flow and fused double melting peaks at Tc = 204 °C support the mechanism of different morphologies. The Hoffman-Weeks linear plot gave an equilibrium melting temperature of 236.3 °C. The kinetic analysis of the growth rates of spherulites and the morphology change from regular to banded spherulites indicated that there existed a regime II → III transition at 196 °C. 相似文献
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研究了彩色自蛇模型的形成过程,对遥感TM图像进行了后处理放大处理,采用最邻近点插值、双线性插值、三次样条插值、双立方插值、双二次插值。针对插值放大后的图像的边缘出现锯齿化和模糊化问题,由于彩色自蛇模型本身不仅具有边缘锐化功能,它可以消除边缘锯齿化和边缘模糊化问题,而且具有去噪的能力。采用彩色自蛇模型进行后处理,并对处理后的残余斑点进行研究,结果采用了中值滤波的方式取得更好的效果,并对含噪的遥感图像也有较好的放大效果,实验结果证明该方法适于遥感图像的放大处理。 相似文献
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All existing fault-tolerance job scheduling algorithms for computational grids were proposed under the assumption that all sites apply the same fault-tolerance strategy. They all ignored that each grid site may have its own fault-tolerance strategy because each site is itself an autonomous domain. In fact, it is very common that there are multiple fault-tolerance strategies adopted at the same time in a large-scale computational grid. Various fault-tolerance strategies may have different hardware and software requirements. For instance, if a grid site employs the job checkpointing mechanism, each computation node must have the following ability. Periodically, the computational node transmits the transient state of the job execution to the server. If a job fails, it will migrate to another computational node and resume from the last stored checkpoint. Therefore, in this paper we propose a genetic algorithm for job scheduling to address the heterogeneity of fault-tolerance mechanisms problem in a computational grid. We assume that the system supports four kinds fault-tolerance mechanisms, including the job retry, the job migration without checkpointing, the job migration with checkpointing, and the job replication mechanisms. Because each fault-tolerance mechanism has different requirements for gene encoding, we also propose a new chromosome encoding approach to integrate the four kinds of mechanisms in a chromosome. The risk nature of the grid environment is also taken into account in the algorithm. The risk relationship between jobs and nodes are defined by the security demand and the trust level. Simulation results show that our algorithm has shorter makespan and more excellent efficiencies on improving the job failure rate than the Min–Min and sufferage algorithms. 相似文献
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La2O3-TiO2非晶氧化物是一种具有优异光学性能的材料, 有着广泛的应用前景, 但其非晶形成能力较差, 通过无容器凝固制备的材料尺寸通常在10 mm以下。为了获得大尺寸La2O3-TiO2非晶氧化物材料, 本研究在La2O3-TiO2氧化物体系中加入少量SiO2。先通过气动悬浮技术制备非晶粉末, 然后用真空热压烧结的方式制备出了高致密度的大块La2O3-TiO2-SiO2材料, 并用XRD、SEM等技术手段进行表征。结果表明: SiO2可以提高La2O3-TiO2体系的非晶形成能力, 通过气动悬浮技术获得的原料粉末呈完全非晶态, 通过热压烧结方式获得的块体材料高度致密, 仅存在少量的气孔。烧结样品有微弱的晶化, 晶化是其无法完全致密的一个重要原因。通过研究烧结曲线, 分析了La2O3-TiO2-SiO2非晶粉末的烧结机制。烧结的La2O3-TiO2-SiO2材料在可见光区域的折射率大于2.2, 具有优异的光学性能。 相似文献
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