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Distributed top-k similarity query on big trajectory streams

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Frontiers of Computer Science 2019年第3期13卷 647-664页

作者： Zhigang ZHANG Xiaodong QI Yilin WANG Cheqing JIN Jiali MAO Aoying ZHOU School of Data Science and Engineering East China Normal University Shanghai 200062 China Computer School China West Normal University Nanchong 637009 China

Recently, big trajectory data streams are generated in distributed environments with the popularity of smartphones and other mobile devices. Distributed top?k similarity query, which finds k trajectories that are most similar to a given query trajectory from all remote sites, is critical in this field. The key challenge in such a query is how to reduce the communication cost due to the limited network bandwidth resource. Although this query can be solved by sending the query trajectory to all the remote sites, in which the pairwise similarities are computed precisely. However, the overall cost, O(n·m),is huge when nor mis huge, where n is the size of query trajectory and m is the number of remote sites. Fortunately, there are some cheap ways to estimate pairwise similarity, which filter some trajectories in advance without precise computation. In order to overcome the challenge in this query, we devise two general frameworks, into which concrete distance measures can be plugged. The former one uses two bounds (the upper and lower bound), while the latter one only uses the lower bound. Moreover, we introduce detailed implementations of two representative distance measures, Euclidean and DTW distance, after inferring the lower and upper bound for the former framework and the lower bound for the latter one. Theoretical analysis and extensive experiments on real-world datasets evaluate the efficiency of proposed methods.

关键词： top-k similarity query trajectory stream communication cost

Event-Driven top-k Queries in Sensor Networks with Multi Microenvironments

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Chinese Journal of Electronics 2015年第2期24卷 373-378页

作者： LI Yinglong LV Mingqi YANG Lianghuai School of Computer Science and Technology Zhejiang University of Technology

In the emerging area of sensor-based systems, a significant challenge is to develop reliable, energy efficient methods to extract useful information from the distributed sensory data. Existing top-k query algorithms of sensor networks are only applicable to the sensor networks with single Microenvironment(ME). Besides, these approaches rely on using raw sensor readings, which handling these raw sensory data requires large amount of data transmission and is memory-consuming. In this paper we highlight the multiple MEs in sensor networks and propose a novel event-driven approximate top-k query framework based on fuzzy method. Firstly, membership function of fuzzy method is introduced to describe the global potential event confidence. Subsequently, non-uniform membership degree subranges based linguistic variables instead of numeric sensor readings are used for in-network top-k event fusion. Also two distributed event-driven approximate top-k query algorithms are devised. Theoretical analysis as well as extensive simulations based on synthetic and real data sets show that our framework reduces the data transmission significantly and the query results are more interpretable with quality guarantees.

关键词： Microenvironment Event linguistic variable Linguistic ranking top-k Fuzzy method Sensor network

Differentially Private top-k Items Based on Least Mean Square——Take E-Commerce Platforms for Example

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Wuhan University Journal of Natural Sciences 2019年第2期24卷 98-106页

作者： CAO Mengyue WU Fusheng NI Mingtao XIONG Xingxing LIU Shubo WANG Jun Department of Foreign Languages Yangtze University College of Arts and Sciences Guizhou key Laboratory of Economics System Simulation Guizhou University of Finance and Economics School of Cyber Science and Engineering Wuhan University School of Computer Science Leshan Normal University School of Computer Wuhan University College of Computer South-Central University for Nationalities

User preference data broadly collected from e-commerce platforms have benefits to improve the user’s experience of individual purchasing recommendation by data mining and analyzing,which may bring users the risk of privacy *** this paper,we explore the problem of differential private top-k items based on least mean ***,we consider the balance between utility and privacy level of released data and improve the precision of top-k based on *** show that our algorithm can achieve differential privacy over streaming data collected and published periodically by server *** evaluate our algorithm with three real datasets,and the experimental results show that the precision of our method reaches 85%with strong privacy protection,which outperforms the kalman filter-based existing methods.

关键词： top-k differential privacy least mean square streaming data

关系数据库中支持语义的top-k关键字搜索(英文)

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软件学报 2008年第9期19卷 2362-2375页

作者：王斌杨晓春王国仁东北大学信息学院辽宁沈阳110004

为了增强关系数据库中的关键字搜索查询结果,考虑了多表之间以及元组之间的语义关系,提出了一种语义评分函数.该语义评分函数不仅涵盖了当前的评分思想,并且加入新指标来衡量查询结果与查询关键字之间的相关性.基于该评分函数,提出两种... 详细信息

为了增强关系数据库中的关键字搜索查询结果,考虑了多表之间以及元组之间的语义关系,提出了一种语义评分函数.该语义评分函数不仅涵盖了当前的评分思想,并且加入新指标来衡量查询结果与查询关键字之间的相关性.基于该评分函数,提出两种以数据块为处理单位的top-k搜索算法,分别为BA(blocking algorithm)算法和EBA(early-stopping blocking algorithm)算法.EBA在BA基础上引入了过滤域值,以便尽早终止算法的迭代次数.最后实验结果显示语义评分函数保证了搜索结果的高查准率和查全率,所提出的BA算法和EBA算法改善了现有方法的查询性能.

关键词： top-k 关键字搜索关系数据库信息检索浠义相似度

kDS-CM:A Cache Mechanism Based on top-k Data Source for Deep Web Query

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Wuhan University Journal of Natural Sciences 2007年第5期12卷 830-834页

作者： kOU Yue SHEN Derong YU Ge LI Dong NIE Tiezheng College of Information Science and Engineering Northeastem University Shenyang 110004 Liaoning China Business Software Division Neusoft Group Limited Company Shenyang 110004 Liaoning China

Caching is an important technique to enhance the efficiency of query processing. Unfortunately, traditional caching mechanisms are not efficient for deep Web because of storage space and dynamic maintenance limitations. In this paper, we present on providing a cache mechanism based on top-k data source （kDS-CM） instead of result records for deep Web query. By integrating techniques from IR and top-k, a data reorganization strategy is presented to model kDS-CM. Also some measures about cache management and optimization are proposed to improve the performances of cache effectively. Experimental results show the benefits of kDS-CM in execution cost and dynamic maintenance when compared with various alternate strategies.

关键词： cache top-k Deep Web data reorganization cache management and optimization

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RDF图的top-k最短路径查询

电子学报 2015年第8期43卷 1531-1537页

作者：章登义吴文李欧阳黜霏武汉大学计算机学院湖北武汉430072

最短路径查询是图数据管理与复杂关系挖掘的基本操作之一．本文针对资源描述框架图上的top-k最短路径查询，构造基于组件的索引，并在该索引的基础上实现查询的响应．查询优化阶段，针对查询效率问题，提出频繁路径以及结构剪枝策略，... 详细信息

最短路径查询是图数据管理与复杂关系挖掘的基本操作之一．本文针对资源描述框架图上的top-k最短路径查询，构造基于组件的索引，并在该索引的基础上实现查询的响应．查询优化阶段，针对查询效率问题，提出频繁路径以及结构剪枝策略，并给出有效性证明．实验表明，本文方法准确返回top-k最短路径并提高92％的查询速率．索引构造时间相比已有方法，提高约56％．同时，索引所占空间仅为原始数据大小的1～1．2倍．

关键词：资源描述框架最短路径查询图数据库 top-k 查询处理

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基于外存后缀树的top-k局部比对算法

计算机学报 2016年第10期39卷 2061-2074页

作者：王斌朱睿杨晓春王国仁于戈东北大学信息科学与工程学院沈阳110004

局部比对是一种衡量字符串间相似程度的技术,它在生物信息学领域具有十分重要的作用.介于此,许多学者已对其进行了深入的研究.然而,随着数据规模的扩大,常规的内存算法已不适用于支持大规模文本数据的局部比对.为解决上述问题,该文研究... 详细信息

局部比对是一种衡量字符串间相似程度的技术,它在生物信息学领域具有十分重要的作用.介于此,许多学者已对其进行了深入的研究.然而,随着数据规模的扩大,常规的内存算法已不适用于支持大规模文本数据的局部比对.为解决上述问题,该文研究了基于外存后缀树的top-k局部比对算法.它从根本上消除了内存空间对算法的束缚.为了提高算法的性能,该文首先将经典内存算法中的过滤策略引入该文.通过适当的修改,这些策略可以基于外存后缀树有效地降低计算开销.其次,该文提出一种巧妙的算法支持top-k局部比对查询.该算法通过引入启发式策略有效规避了TA算法的固有问题.具体地,它一方面可以提高算法的过滤能力,另一方面可以降低候选对象的维护代价.再次,该文对外存后缀树和磁盘的工作原理进行了研究.基于此,该文提出一种槽的结构支持查询.该结构既可以实现磁盘的顺序访问,又可以降低磁盘的访问次数.因此,它可以有效提高算法的查询效率.最后,大量的实验验证了该文所提出算法的有效性.

关键词：局部比对 top-k 外存后缀树叉子区域

基于多关键字的top-k布尔可搜索加密方案

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计算机研究与发展 2022年第8期59卷 1841-1852页

作者：郭斯栩何申粟栗张星周福才张鑫月中国移动通信有限公司研究院安全技术研究所北京100053 东北大学软件学院沈阳110819

针对在云存储服务中可搜索加密技术的研究,解决了现存3个问题:1)传统可搜索加密方法大多数只支持单关键字搜索,并且在安全索引过大时,搜索时间代价过大;2)现有方案大多使用倒排索引进行快速搜索,然而倒排索引并不支持动态关键字更新;3)... 详细信息

针对在云存储服务中可搜索加密技术的研究,解决了现存3个问题:1)传统可搜索加密方法大多数只支持单关键字搜索,并且在安全索引过大时,搜索时间代价过大;2)现有方案大多使用倒排索引进行快速搜索,然而倒排索引并不支持动态关键字更新;3)现有方案大多数无法针对某些按需用户,根据关键字的重要性对搜索文件进行安全高效的top-k排序.提出了一种基于多关键字的top-k布尔可搜索加密方案(top-k boolean searchable encryption scheme based on multiple keywords,TBSE).该方案利用Goldwasser-Micalli与2DNF这2种加密算法构建了一种支持动态更新的安全索引;利用集合论与布尔搜索的相关知识构建了关键字交集索引与交集搜索令牌,以实现对多关键字的布尔搜索;利用TF-IDF加权技术与安全协处理器构造分数索引,进而能够对文件进行top-k排序.安全性分析表明:该方案保证了在已知密文模型与已知背景模型下的安全性.通过实验证明:该方案提升了对多关键字布尔搜索的效率以及索引存储的效率.

关键词：布尔搜索多关键字 top-k 可搜索加密动态更新

基于覆盖码预排序的数据立方体部分和top-k查询算法

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北京大学学报（自然科学版） 2007年第1期43卷 55-60页

作者：张卫华谭少华殷普杰张煜宇成富北京大学信息科学技术学院视觉与听觉信息处理国家重点实验室北京100871

在决策支持系统中,排序查询是研究的热点问题。提出了一种在OLAP(数据仓库)数据立方体中对部分和查询结果进行排序的高效算法,该算法综合利用覆盖码和预排序,有效地解决了对部分和结果的top-k查询问题。实验结果表明无论数据在随机分布... 详细信息

在决策支持系统中,排序查询是研究的热点问题。提出了一种在OLAP(数据仓库)数据立方体中对部分和查询结果进行排序的高效算法,该算法综合利用覆盖码和预排序,有效地解决了对部分和结果的top-k查询问题。实验结果表明无论数据在随机分布还是存在主导集情况下,该算法都能很好地改进查询的时间代价。

关键词：联机分析处理部分和 top-k 覆盖码