Motivated by this observation , this paper studies the problem of efficiently processing k nn k - ge 1 search on r - tree - like structures storing historical information about moving object trajectories . two algorithms are developed based on best - first traversal paradigm , called bfp k nn and bft k nn , which handle the k nn retrieval with respect to the static query point and the moving query trajectory , respectively . both algorithms minimize the number of node access , that is , they perform a single access only to those qualifying nodes that may contain the final result 例如，若已知动物的轨迹，则动物学家可能提出如下两种查询： i在时间区间ti , tj内找到离一个给定的静态点譬如食物源实验室等最近的k条动物轨迹ii在时间区间ti , tj内找到离一条预先指定的动物轨迹最近的k条动物轨迹。
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The thesis , somehow , is a summary , which expounds the main contents of traditional portfolio theory ( tpt ) and mpt , also gives a comparison between tpt and mpt ; analyses two aspects of markowitz theory , one is the effects of risk disperses and the demonstration , the other is how to make an optimal portfolio strategy ; researches into capital assets pricing model ( capm ) , factor model ( fm ) and arbitrage pricing theory ( apt ) respectively in three parts ; studies another two parts , one is the premise of mpt , which is the efficient market hypothesis ( emh ) , the other analyses the behavior finance theory ( bft ) produced in the background of challenging and querying to emt and capm . the thesis finally discusses the researching and applying prospects of mpt in china 论文对现代资产组合理论与传统资产组合理论分别进行了分析，并对两者进行了比较研究，对马克维茨的均值? ?方差理论从资产组合风险分散效应和最优资产组合选择两方面进行了重点分析，对资本资产定价模型、因素模型、套利定价理论进行了一定深度的分析和研究，对现代资产组合理论的前提假设? ?有效市场理论及在对有效市场理论和资本资产定价模型形成挑战和质疑背景下提出的行为金融理论进行了论述，论文最后分析了现代资产组合理论在我国的研究及其应用的广阔前景。
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