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The pattern of cross stream migration of neutrally buoyant particles in a pressure driven flow depends strongly on the properties of the suspending fluid. These migration effects have been studied by direct numerical simulation in planar flow. Shear thinning has a large effect when the inertia or elasticity is large, but only a small effect when they are small. At moderate Reynolds numbers, shear thinning causes particles to migrate away from the centerline, creating a particle-free zone in the core of the channel, which increases with the amount of shear thinning. In a viscoelastic fluid with shear thinning, particles migrate either toward the centerline or toward the walls, creating an annular particle-free zone at intermediate radii. The simulations also give rise to precise determination of slip velocity distributions in the various cases studied. 相似文献
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We analyze the network of cross-border bank lending connections among countries from 1977 to 2018. The network includes core countries that lend money and peripheral countries that borrow money from core countries. In nowadays highly connected banking network, financial crisis that start from a country can spread to other countries very fast and cause global affects. We use principal component analysis (PCA) to find the influential lending (core) countries in this network over the years and clusters of borrowing (peripheral) countries related to these impactful core countries. We find three clusters of peripheral countries, with some constant and some changing members over time. This can be a sign of changes in the financial or political interactions among countries. The changes in the role of core countries and how these roles get affected by the important financial crisis in the past decades is investigated. Among 31 of core countries, 7 countries have a partially or constantly important role in the network including France, United Kingdom, United States, Japan, Germany, Chinese Taipei and Switzerland. 相似文献
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E. O. Aleksanyan E. M. Laziev M. L. Movsisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(5):245-250
An opportunity of using the 20 MeV Linac at YerPhI as a driver of THz-FELs is considered. The basic parameters of the Linac and FELs are given. Requirements to the electron beam and Linac systems are determined. 相似文献
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研究了DVB传输流实时捕获系统的结构及其实现方法.该系统的硬件利用复杂可编程逻辑器件和总线接口芯片,实现了传输流与PcI总线之间的接口,软件利用设备驱动程序将硬件采集的数据流传入计算机.同时保证了高速的数据交换速率,可以对捕获的数据流进行实时的处理,该系统在DvB的分析、测试、存储、编辑和复用中都有着广阔的应用前景. 相似文献
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氙灯提供的有效抽运能量决定了钕玻璃中反转粒子的数目。针对氙灯供能的要求,建立了氙灯放电回路与氙灯辐射数值模型。将数值模拟结果与实验结果进行了比对,提出了利用模拟退火算法求解最优抽运状态的电路参数的方法,并模拟计算不同电路参数下氙灯的工作状态。定义了两个更实用的评价参数:有效辐射效率和有效输出光谱效率,用于筛选最佳的抽运能量和进灯功率。计算结果表明,在氙灯参数与工作电压一定的条件下,通过利用模拟退火算法可以快速优化放电回路中的电容、电感参数,以选择最佳的进灯能量,避免抽运带内有效能量份额因光谱蓝移而降低,同时可保证氙灯的使用寿命。 相似文献
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Through-silicon-via crosstalk model and optimization design for three-dimensional integrated circuits
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Through-silicon-via (TSV) to TSV crosstalk noise is one of the key factors affecting the signal integrity of three- dimensional integrated circuits (3D ICs). Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 rnV and 379 mV reductions in the peak noise voltage, respectively. 相似文献
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针对直线变压器驱动源(LTD)对开关的长寿命需求,基于前期研制的200kV低抖动多间隙气体开关电极几何参数以及开关通流水平,详细开展了不同电极材料(钼、黄铜、铜钨合金、高密度石墨、304和321不锈钢)的烧蚀性能实验。实验结果表明,在单次电荷转移量15.4mC,脉冲电流20kA条件下,体积烧蚀速率从大到小依次为:石墨、黄铜、铜钨合金、钼、不锈钢。电极烧蚀微观形貌分析表明,不锈钢是用于LTD开关相对较好的电极材料。根据不锈钢电极的体积烧蚀速率,可知理论上LTD开关的运行寿命可以超过1×106次,但前提是开关外壳需保持足够的绝缘强度。 相似文献