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一种具有连续跳数值的三维DV-Hop改进算法 被引量:16
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作者 程杰 董云玲 +1 位作者 陈嘉兴 刘志华 《电子学报》 EI CAS CSCD 北大核心 2020年第11期2122-2130,共9页
设计精确的定位算法是无线传感器网络(Wireless Sensor Networks,WSNs)的研究热点.针对DV-Hop(Distance Vector-Hop)定位算法中节点间距离估计误差较大导致定位不精确的问题,提出了一种具有连续跳数值的三维DV-Hop改进算法.探究了邻居... 设计精确的定位算法是无线传感器网络(Wireless Sensor Networks,WSNs)的研究热点.针对DV-Hop(Distance Vector-Hop)定位算法中节点间距离估计误差较大导致定位不精确的问题,提出了一种具有连续跳数值的三维DV-Hop改进算法.探究了邻居节点间的距离与相应节点位置和通信半径构成的相交球体体积之间的关系,提出了连续跳数值的定义,并通过参数修正给出了其计算方法.通过仿真实验探究了网络环境对参数的影响并确定了参数的取值,使用连续跳数值代替DV-Hop算法中的跳数来降低节点间距离估计误差.仿真实验表明,该算法在不增加算法复杂度以及额外硬件的情况下有效地降低了定位误差. 展开更多
关键词 无线传感器网络 DV-HOP定位 相交球体 连续跳数值 参数修正
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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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