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As an important type of multidimensional preference query, the skyline query can find a superset of optimal results when there is no given linear function to combine values for all attributes of interest. Its processing has been extensively investigated in the past. While most skyline query processing algorithms are designed based on the assumption that query processing is done for all attributes in a static dataset with deterministic attribute values, some advanced work has been done recently to remove part of such a strong assumption in order to process skyline queries for real-life applications, namely, to deal with data with multi-valued attributes (known as data uncertainty), to support skyline queries in a subspace which is a subset of attributes selected by the user, and to support continuous queries on streaming data. Naturally, there are many application scenarios where these three complex issues must be considered together. In this paper, we tackle the problem of probabilistic subspace skyline query processing over sliding windows on uncertain data streams. That is, to retrieve all objects from the most recent window of streaming data in a user-selected subspace with a skyline probability no smaller than a given threshold. Based on the subtle relationship between the full space and an arbitrary subspace, a novel approach using a regular grid indexing structure is developed for this problem. An extensive empirical study under various settings is conducted to show the effectiveness and efficiency of our PSS algorithm. 相似文献
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轨迹大数据:数据、应用与技术现状 总被引:1,自引:0,他引:1
移动互联技术的飞速发展催生了大量的移动对象轨迹数据。这些数据刻画了个体和群体的时空动态性,蕴含着人类、车辆、动物的行为信息,对交通导航、城市规划、车辆监控等应用具有重要的价值。为了实现有效的轨迹数据价值提取,近年来学术界和工业界针对轨迹管理问题开展了大量研究工作,包括轨迹数据预处理,以解决数据冗余高、精度差、不一致等问题;轨迹数据库技术,以支持有效的数据组织和高效的查询处理;轨迹数据仓库,支持大规模轨迹的统计、理解和分析;最后是知识提取,从数据中挖掘有价值的模式与规律。因此,综述轨迹大数据分析,从企业数据、企业应用、前沿技术这3个角度揭示该领域的现状。 相似文献
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针对高清电视应用,实现了面向H.264主层面CABAC解码模块输出之后的宏块残差的顺序调整、反变换和反量化操作。借助高效组织的SRAM,本设计有效地连接了残差调序和反变换反量化两个部分,硬件资源得以充分利用,较好地解决了残差调序的时间瓶颈。同时,根据帧内帧间预测情况下亮度和色度的反变换反量化的算法,通过适当变换,采用同一块电路实现了所有情况下的操作。 相似文献
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为解决纯软件的Java卡虚拟机(JCVM)在嵌入式系统中解释执行速度较慢、效率低的性能问题,软硬件协同方式设计面向家庭网络(Home Network)的Java协处理器,对部分JCVM指令使用硬件电路来加速执行.并且在硬件加速的过程中采用流水线结构、环形指令缓存、指令折叠等方式来进一步提高电路速度. 相似文献
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提出了一种快速、高效专用于JPEG2000中EBCOT算法的VLSI结构.根据用于提高EBCOT算法处理速度的多种加速技术,提出了一种“探测——编码”方法,即先找出下一个待编码比特的位置,然后再对其进行编码.这样三次编码过程的扫描量实质上只相当于一次全扫描,编码效率提高了三倍.根据馥方法本文中的结构建立两级流水线操作方式,将编码过程分为:“探测”和“编码”两个处理过程.从而处理速度得到极大的提高.最后.对本文的结构进行了VLSI实现和验证.并在结构的面积,速度和功耗等方面和同类结构进行了比较,可以看出本文中的结构具有高的处理速度和较低的功耗. 相似文献
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