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边界约束的非相交球树实体对象多维统一索引 被引量:5
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作者 俞肇元 袁林旺 +2 位作者 罗文 胡勇 闾国年 《软件学报》 EI CSCD 北大核心 2012年第10期2746-2759,共14页
针对现有空间索引剖分结构复杂、节点重叠率高及对多维实体对象检索及运算支撑较弱等问题,构建了一种边界约束的非相交球实体对象多维统一空间索引;利用球的几何代数外积表达,提出了基于求交算子的直线-平面和直线-球面的相交判定与交... 针对现有空间索引剖分结构复杂、节点重叠率高及对多维实体对象检索及运算支撑较弱等问题,构建了一种边界约束的非相交球实体对象多维统一空间索引;利用球的几何代数外积表达,提出了基于求交算子的直线-平面和直线-球面的相交判定与交点提取方法,建立了多维实体对象体元化剖分方法及包含边界约束的非相交离散球实体填充算法,实现了实体对象空间均匀、非重叠的分割,并在填充球的个数、重叠率以及对象逼近近似度等约束条件上获得了较好的平衡.定义了最小外包球生成与更新的迭代算法与包含球体积修正的批量Neural Gas层次聚类算法,在尽可能保证球树各分支平衡性的前提下,实现了索引层次体系的稳健构建.利用几何代数下球对象间几何关系计算的内蕴性与参数更新的动态性,实现了索引结构的动态生成与更新,进而设计了实体对象表面及其内部任意位置及区域的检索策略及基于实体索引的空间关系计算方法.基于不同实体对象的模拟实验显示,基于几何代数的实体对象索引可以有效实现多维实体对象表面及其内部任意位置及区域的快速检索,并能在有限时间内以较高的精度实现多维实体对象最近邻距离和动态实体对象相交状态的检索.相对于常用球树索引,所提出的索引方法在填充率、节点重叠率、填充误差、体元个数、层次球个数、体积百分比和时间占用等方面均具有明显优势,且不同分辨率剖分条件下的索引结构及空间关系计算精度具有更高的稳健性,可运用于具有较强时间约束下复杂多维动态场景中对象检索与空间关系计算. 展开更多
关键词 多维统一空间索引 相交球 空间剖分 空间聚类 实体对象索引
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相交球孤立导体的静电问题
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作者 杜召海 崔元顺 《牡丹江师范学院学报(自然科学版)》 1997年第1期54-57,共4页
用环坐标系研究一类相交球孤立导体的静电问题。其结果对分析某些导体结构的电场和电位分布具有一定的理论意义。
关键词 相交球 孤立导体 静电问题 环坐标系
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Cn中双球相交域上的奇异积分方程
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作者 龚定东 郭玉琴 《数学物理学报(A辑)》 CSCD 北大核心 2022年第1期18-25,共8页
C;中双球相交域上具有全纯核的奇异积分的Sokhotsky-Plemelj公式具有一种特殊的形式,它在边界上是分片连续的.利用这个Sokhotsky-Plemelj公式,在适当条件下得到了一个特殊的合成公式,并得到了常系数奇异积分方程和方程组的特征方程一个... C;中双球相交域上具有全纯核的奇异积分的Sokhotsky-Plemelj公式具有一种特殊的形式,它在边界上是分片连续的.利用这个Sokhotsky-Plemelj公式,在适当条件下得到了一个特殊的合成公式,并得到了常系数奇异积分方程和方程组的特征方程一个直接解,并把常系数奇异积分方程和方程组化为一类与之等价的Fredholm型方程和方程组. 展开更多
关键词 复双相交 合成公式 奇异积分方程 奇异积分方程组
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基于MATLAB的导弹毁伤效能数值计算效率优化方法
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作者 肖师云 陈文 《火箭军工程大学学报》 2024年第3期1-8,共8页
为解决蒙特卡洛仿真法评估导弹毁伤效能计算时间长、效率低的问题,研究了一种基于MATLAB的导弹毁伤效能仿真计算效率优化方法。在建立一体化目标易损性模型和战斗部威力场模型的基础上,应用包围球相交检测法实现破片射击线与目标部件相... 为解决蒙特卡洛仿真法评估导弹毁伤效能计算时间长、效率低的问题,研究了一种基于MATLAB的导弹毁伤效能仿真计算效率优化方法。在建立一体化目标易损性模型和战斗部威力场模型的基础上,应用包围球相交检测法实现破片射击线与目标部件相交的快速检测,并建立了交点求解优化算法;基于MATLAB编制了导弹毁伤效能快速数值计算程序。实例结果表明:与常规线面相交求解算法相比,优化方法的计算效率提高了约16倍。 展开更多
关键词 杀伤概率 目标易损性 战斗部威力场 蒙特卡洛仿真 包围相交检测
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The 2007-2009 Financial Crisis on Emerging Markets: Quantitative Identification of Crisis in Continent-based Regions
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作者 Joanna Olbrys Elzbieta Majewska 《Chinese Business Review》 2014年第7期411-426,共16页
This paper focuses on a direct quantitative identification of crisis periods in selected emerging stock markets from four continent-based regions of Europe, Latin America, East Asia, and Middle East and North Africa ... This paper focuses on a direct quantitative identification of crisis periods in selected emerging stock markets from four continent-based regions of Europe, Latin America, East Asia, and Middle East and North Africa (MENA), in the context of an influence of the 2007 U.S. subprime financial crisis. The 17 emerging stock markets and, for comparison, the U.S. stock market are investigated. A statistical method of dividing market states into bullish and bearish markets, based on monthly logarithmic returns of major stock market indexes, is employed. The analyzed sample period begins in January 2003 and ends in December 2013. As there is no unanimity in the literature about the crisis periods in the continent-based regions, a formal statistical identification of crises is worthwhile to conduct. Furthermore, the effect of increasing cross-market correlations in the crisis compared to the pre-crisis period in the context of contagion is examining. To address this issue, both standard contemporaneous cross-correlations and volatility-adjusted cross-correlations are applied. The results are consistent with the literature and confn'm that tests for contagion based on cross-market correlations are problematic due to the bias introduced by changing volatility in market returns. As contagion can be confused with globalization, the globalization tests in the group of international investigated markets are employed. The results generally do not confirm a global world market integration effect, i.e. there is no reason to reject the research hypothesis of no globalization during the 2007-2009 financial crisis. 展开更多
关键词 emerging markets market states cross-market correlations contagion GLOBALIZATION
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The Power of Language: Globalizing "The Chinese Dream" 被引量:1
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作者 Anny Boc 《Fudan Journal of the Humanities and Social Sciences》 2015年第4期533-551,共19页
After assuming the Chinese presidency in March 2013, Xi Jinping introduced the new political slogan "the Chinese Dream," which he does not only address to the domestic audience but also aims to promote to the world.... After assuming the Chinese presidency in March 2013, Xi Jinping introduced the new political slogan "the Chinese Dream," which he does not only address to the domestic audience but also aims to promote to the world. Since his inaugural trip abroad, Xi has repeatedly speeches when addressing international catchphrase received as much appeal as used the term "Chinese Dream" in his audiences. However, nowhere has the in Africa. Simultaneously, African academics and other interested parties have observed the promotion of the idea of an African Dream by the Chinese Communist Party (CCP) with great suspicion as they view it simply as a projection of China's own foreign policy onto Africa. But what do the Chinese Dream and African Dream actually mean? How can we make sense out of these terms? In order to decode or demystify the meaning behind the Chinese Dream narrative in the context of China's foreign policy, this paper argues that it is essential to examine how it is constructed and projected to the international audience, in particular to Africa. The Chinese Dream is understood as a narrative which is strategically used by the CCP in order to shape perceptions and behavior of other international actors according to their own agenda. Moreover, the dynamic interactions between the media and politics and how they impinge on the formation and projection of the Chinese Dream and African Dream narrative will also be taken into account. 展开更多
关键词 African Dream · Chinese Dream ·Critical discourse analysis ·Foreign policy ·Media ·Strategic narratives
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