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Semantic-based query processing for relational data integration 认领 引用 被引量：1
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作者 苗壮 张亚非 +2 位作者 王进鹏 陆建江 周波 《Journal of Southeast University(English Edition)》 EI CAS 2011年第1期22-25,共4页
To solve the query processing correctness problem for semantic-based relational data integration,the semantics of SAPRQL（simple protocol and RDF query language） queries is defined.In the course of query rewriting,al... To solve the query processing correctness problem for semantic-based relational data integration,the semantics of SAPRQL（simple protocol and RDF query language） queries is defined.In the course of query rewriting,all relative tables are found and decomposed into minimal connectable units.Minimal connectable units are joined according to semantic queries to produce the semantically correct query plans.Algorithms for query rewriting and transforming are presented.Computational complexity of the algorithms is discussed.Under the worst case,the query decomposing algorithm can be finished in O（n2） time and the query rewriting algorithm requires O（nm） time.And the performance of the algorithms is verified by experiments,and experimental results show that when the length of query is less than 8,the query processing algorithms can provide satisfactory performance. 展开更多
关键词 data integration relational database simple protocol and RDF query language（SPARQL） minimal connectable unit query processing
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Storage optimization for query processing over data streams 认领 引用
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作者 唐向红 《Journal of Chongqing University》 2010年第2期79-92,共14页
A defining characteristic of continuous queries over on-line data streams,possibly bounded by sliding windows,is the potentially infinite and time-evolving nature of their inputs and outputs.For different update patte... A defining characteristic of continuous queries over on-line data streams,possibly bounded by sliding windows,is the potentially infinite and time-evolving nature of their inputs and outputs.For different update patterns of continuous queries,suitable data structures bring great query processing efficiency.In this paper,we proposed a data structure suitable for weak nonmonotonic update pattern in which the lifetime of each tuple is known at generation time,but the length of lifetime is not necessarily the same.The new data structure combined the ladder queue with the feature of weak non-monotonic update pattern.The experiment results show that the new data structure performs much better than the traditional calendar queue in many cases. 展开更多
关键词 calendar queue ladder queue query processing sliding windows
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Caching Document Identifiers to Speedup Query Processing in Search Servers 认领 引用
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作者 Gabriel H.Tolosa Pablo Lavallén Esteban A Ríssola 《Journal of Computer Science & Technology》 SCIE EI CSCD 2025年第3期870-886,共17页
Modern search systems have become a fundamental tool for accessing the massive amount of information stored in different repositories.These systems use sophisticated techniques to efficiently process a high volume of ... Modern search systems have become a fundamental tool for accessing the massive amount of information stored in different repositories.These systems use sophisticated techniques to efficiently process a high volume of queries(thus optimizing energy consumption).One of these techniques is caching,which is implemented at different levels of a search architecture.In this work,we propose a novel caching strategy that speeds up dynamic pruning techniques(such as Maxscore)by exploiting the information of the lowest(Min)and highest(Max)document identifiers that appear as the result of a previously submitted query.We name this technique as Min/Max caching.The idea is to use Min/Max information for pruning the terms’posting lists in the query before executing the ranking algorithm in a document-at-a-time(DAAT)approach.The proposed technique uses low memory resources,returns safe results,and complements other levels of caching(if present).We also combine the approach with different access policies.Extensive experimentation on real-world data shows that the proposed method increases query processing speedup up to 1.23x and can also reduce high-percentile tail latency(up to 2.0x speedup),an essential requirement for operational scenarios.We evaluate different access and eviction cache policies based on different decision criteria.Our findings confirm that considering the cost of the cached items(cost-aware policies)allows more computation savings. 展开更多
关键词 caching efficiency query processing search
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k-Nearest Neighbor Query Processing Algorithms for a Query Region in Road Networks 认领 引用 被引量：10
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作者 Hyeong-Il Kim Jae-Woo Chang 《Journal of Computer Science & Technology》 SCIE EI CSCD 2013年第4期585-596,共12页
Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations... Recent development of wireless communication technologies and the popularity of smart phones .are making location-based services （LBS） popular. However, requesting queries to LBS servers with users＇ exact locations may threat the privacy of users. Therefore, there have been many researches on generating a cloaked query region for user privacy protection. Consequently, an efficient query processing algorithm for a query region is required. So, in this paper, we propose k-nearest neighbor query （k-NN） processing algorithms for a query region in road networks. To efficiently retrieve k-NN points of interest （POIs）, we make use of the Island index. We also propose a method that generates an adaptive Island index to improve the query processing performance and storage usage. Finally, we show by our performance analysis that our k-NN query processing algorithms outperform the existing k-Range Nearest Neighbor （kRNN） algorithm in terms of network expansion cost and query processing time. 展开更多
关键词 island index k-nearest neighbor query processing scheme locatiombased service road network
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Dominant Skyline Query Processing over Multiple Time Series 认领 引用 被引量：1
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作者 汪浩 王朝坤 +1 位作者 徐亚军 宁苑池 《Journal of Computer Science & Technology》 SCIE EI CSCD 2013年第4期625-635,共11页
Multiple time series （MTS）, which describes an object in multi-dimensions, is based on single time series and has been proved to be useful. In this paper, a new analytical method called α/β-Dominant-Skyline on MTS... Multiple time series （MTS）, which describes an object in multi-dimensions, is based on single time series and has been proved to be useful. In this paper, a new analytical method called α/β-Dominant-Skyline on MTS and a formal definition of the α/β-dominant skyline MTS are given. Also, three algorithms, called NL, BC and MFB, are proposed to address the α/β-dominant skyline queries over MTS. Finally experimental results on both synthetic and real data verify the correctness and effectiveness of the proposed method and algorithms. 展开更多
关键词 multiple time series α/β-dominant skyline skyline query processing
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Improving the performance of query processing using proposed resilient distributed processing technique 认领 引用 被引量：1
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作者 C.Lakshmi K.Usha Rani 《International Journal of Intelligent Computing and Cybernetics》 EI 2021年第2期158-169,共12页
Purpose-Resilient distributed processing technique(RDPT),in which mapper and reducer are simplified with the Spark contexts and support distributed parallel query processing.Design/methodology/approach-The proposed wo... Purpose-Resilient distributed processing technique(RDPT),in which mapper and reducer are simplified with the Spark contexts and support distributed parallel query processing.Design/methodology/approach-The proposed work is implemented with Pig Latin with Spark contexts to develop query processing in a distributed environment.Findings-Query processing in Hadoop influences the distributed processing with the MapReduce model.MapReduce caters to the works on different nodes with the implementation of complex mappers and reducers.Its results are valid for some extent size of the data.Originality/value-Pig supports the required parallel processing framework with the following constructs during the processing of queries:FOREACH;FLATTEN;COGROUP. 展开更多
关键词 Query processing MapReduce Scalability Resilient distributed processing Spark
Processing Constrained K Closest Pairs Query in Spatial Databases 认领 引用 被引量：1
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作者 LIU Xiaofeng LIU Yunsheng XIAO Yingyuan 《Wuhan University Journal of Natural Sciences》 EI CAS 2006年第3期543-546,共4页
In this paper, constrained K closest pairs query is introduced, wbich retrieves the K closest pairs satisfying the given spatial constraint from two datasets. For data sets indexed by R trees in spatial databases, thr... In this paper, constrained K closest pairs query is introduced, wbich retrieves the K closest pairs satisfying the given spatial constraint from two datasets. For data sets indexed by R trees in spatial databases, three algorithms are presented for answering this kind of query. Among of them, two-phase Range＋Join and Join＋Range algorithms adopt the strategy that changes the execution order of range and closest pairs queries, and constrained heap-based algorithm utilizes extended distance functions to prune search space and minimize the pruning distance. Experimental results show that constrained heap-base algorithm has better applicability and performance than two-phase algorithms. 展开更多
关键词 spatial databases query processing R-tree closest pairs query constrained closest pairs query
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AbIx: An Approach to Content-Based Approximate Query Processing in Peer-to-Peer Data Systems 认领 引用
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作者 王朝坤 王建民 +2 位作者 孙家广 石胜飞 高宏 《Journal of Computer Science & Technology》 SCIE EI 2007年第2期280-286,共7页
In recent years there has been a significant interest in peer-to-peer （P2P） environments in the community of data management. However, almost all work, so far, is focused on exact query processing in current P2P dat... In recent years there has been a significant interest in peer-to-peer （P2P） environments in the community of data management. However, almost all work, so far, is focused on exact query processing in current P2P data systems. The autonomy of peers also is not considered enough. In addition, the system cost is very high because the information publishing method of shared data is based on each document instead of document set. In this paper, abstract indices （AbIx） are presented to implement content-based approximate queries in centralized, distributed and structured P2P data systems. It can be used to search as few peers as possible but get as many returns satisfying users＇ queries as possible on the guarantee of high autonomy of peers. Also, abstract indices have low system cost, can improve the query processing speed, and support very frequent updates and the set information publishing method. In order to verify the effectiveness of abstract indices, a simulator of 10,000 peers, over 3 million documents is made, and several metrics are proposed. The experimental results show that abstract indices work well in various P2P data systems. 展开更多
关键词 approximate query processing content-based information retrieval peer-to-peer data systems abstract indices
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Area Query Processing Based on Gray Code in Wireless Sensor Networks 认领 引用
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作者 Chunyu Ai Yueming Duan +1 位作者 Mingyuan Yan Jing He 《Tsinghua Science and Technology》 EI CAS 2012年第5期499-511,共13页
Area query processing is significant for various applications of wireless sensor networks since it can request information of particular areas in the monitored environment. Existing query processing techniques cannot ... Area query processing is significant for various applications of wireless sensor networks since it can request information of particular areas in the monitored environment. Existing query processing techniques cannot solve area queries. Intuitively, centralized processing on Base Station can accomplish area queries via collecting information from all sensor nodes. However, this method is not suitable for wireless sensor networks with limited energy since a large amount of energy is wasted for reporting useless data. This motivates us to propose an energy-efficient in-network area query processing scheme. In our scheme, the monitored area is partitioned into grids, and a unique gray code number is used to represent a Grid ID （GID）, which is also an effective way to describe an area. Furthermore, a reporting tree is constructed to process area merging and data aggregations. Based on the properties of GIDs, subareas can be merged easily and useless data can be discarded as early as possible to reduce energy consumption. For energy-efficiently answering continuous queries, we also design an incremental update method to continuously generate query results. In essence, all of these strategies are pivots to conserve energy consumption. With a thorough simulation study, it is shown that our scheme is effective and energy-efficient 展开更多
关键词 area query area query processing gray code wireless sensor networks
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Diversification on big data in query processing 认领 引用 被引量：1
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作者 Meifan ZHANG Hongzhi WANG +1 位作者 Jianzhong LI Hong GAO 《Frontiers of Computer Science》 SCIE EI CSCD 2020年第4期135-154,共20页
Recently,in the area of big data,some popular applications such as web search engines and recommendation systems,face the problem to diversify results during query processing.In this sense,it is both significant and e... Recently,in the area of big data,some popular applications such as web search engines and recommendation systems,face the problem to diversify results during query processing.In this sense,it is both significant and essential to propose methods to deal with big data in order to increase the diversity of the result set.In this paper,we firstly define the diversity of a set and the ability of an element to improve the overall diversity.Based on these definitions,we propose a diversification framework which has good performance in terms of effectiveness and efficiency.Also,this framework has theoretical guarantee on probability of success.Secondly,we design implementation algorithms based on this framework for both numerical and string data.Thirdly,for numerical and string data respectively,we carry out extensive experiments on real data to verify the performance of our proposed framework,and also perform scalability experiments on synthetic data. 展开更多
关键词 diversification query processing big data
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Non-Intrusive Elastic Query Processing in the Cloud 认领 引用
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作者 Ticiana L. Coelho da Silva Mario A. Nascimento +2 位作者 Jose Antonio F. de Macedo Flavio R. C. Sousa Javam C. Machado 《Journal of Computer Science & Technology》 SCIE EI CSCD 2013年第6期932-947,共16页
Cloud computing is a very promising paradigm of service-oriented computing. One major benefit of cloud computing is its elasticity, i.e., the system＇s capacity to provide and remove resources automatically at runtime... Cloud computing is a very promising paradigm of service-oriented computing. One major benefit of cloud computing is its elasticity, i.e., the system＇s capacity to provide and remove resources automatically at runtime. For that, it is essential to design and implement an efficient and effective technique that takes full advantage of the system＇s potential flexibility. This paper presents a non-intrusive approach that monitors the performance of relational database management systems in a cloud infrastructure, and automatically makes decisions to maximize the efficiency of the provider＇s environment while still satisfying agreed upon ＂service level agreements＂ （SLAs）. Our experiments conducted on Amazon＇s cloud infrastructure, confirm that our technique is capable of automatically and dynamically adjusting the system＇s allocated resources observing the SLA. 展开更多
关键词 elasticity query processing non-intrusive service level agreement
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RPE Query Processing and Optimization Techniques for XML Databases 认领 引用 被引量：7
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作者 Guo-RenWang BingSun Jian-HuaLv GeYu 《Journal of Computer Science & Technology》 SCIE EI 2004年第2期224-237,共14页
An extent join to compute path expressions containing parent-children andancestor-descendent operations and two path expression optimization rules, path-shortening andpath-complementing, are presented in this paper. P... An extent join to compute path expressions containing parent-children andancestor-descendent operations and two path expression optimization rules, path-shortening andpath-complementing, are presented in this paper. Path-shortening reduces the number of joins byshortening the path while path-complementing optimizes the path execution by using an equivalentcomplementary path expression to compute the original one. Experimental results show that thealgorithms proposed are more efficient than traditional algorithms. 展开更多
关键词 XML regular path expressions query processing and optimization
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Range Query Processing in Multidisk Systems 认领 引用 被引量：1
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作者 李建中 《Journal of Computer Science & Technology》 SCIE EI 1992年第4期316-327,共12页
In order to reduce the disk access time, a database can be stored on several simultaneously accessi- ble disks. In this paper, we are concerned with the dynamic d-attribute database allocation problem for range querie... In order to reduce the disk access time, a database can be stored on several simultaneously accessi- ble disks. In this paper, we are concerned with the dynamic d-attribute database allocation problem for range queries. An allocation method, called coordinate modulo allocation method, is proposed to al- locate data in a d-attribute database among disks so that the maximum disk accessing concurrency can be achieved for range queries. Our analysis and experiments show that the method achieves the optimum or near-optimum parallelism for range queries. The paper offers the conditions under which the method is optimal. The worst case bounds of the performance of the method are also given. In addi- tion, the parallel algorithm of processing range queries is described at the end of the paper. The meth- od has been used in the statistic and scientific database management system which is being designed by us. 展开更多
关键词 Pro Range Query Processing in Multidisk Systems CMA
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A Processing Approach for Event-Based Location Aware Queries in Hybrid Wireless Sensor Networks 认领 引用
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作者 HONG Liang LU Yansheng 《Wuhan University Journal of Natural Sciences》 CAS 2009年第4期327-332,共6页
In hybrid wireless sensor networks,sensor mobility causes the query areas to change dynamically.Aiming at the problem of inefficiency in processing the data aggregation queries in dynamic query areas,this paper propos... In hybrid wireless sensor networks,sensor mobility causes the query areas to change dynamically.Aiming at the problem of inefficiency in processing the data aggregation queries in dynamic query areas,this paper proposes a processing approach for event-based location aware queries(ELAQ),which includes query dissemination algorithm,maximum distance projection proxy selection algorithm,in-network query propagation,and aggregation algorithm.ELAQs are triggered by the events and the query results are dependent on mobile sensors'location,which are the characteristics of ELAQ model.The results show that compared with the TinyDB query processing approach,ELAQ processing approach increases the accuracy of the query result and decreases the query response time. 展开更多
关键词 query processing wireless sensor network mobility data aggregation event
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Learned Distributed Query Optimizer:Architecture and Challenges 认领 引用
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作者 GAO Jun HAN Yinjun +2 位作者 LIN Yang MIAO Hao XU Mo 《ZTE Communications》 2024年第2期49-54,共6页
The query processing in distributed database management systems(DBMS)faces more challenges,such as more operators,and more factors in cost models and meta-data,than that in a single-node DMBS,in which query optimizati... The query processing in distributed database management systems(DBMS)faces more challenges,such as more operators,and more factors in cost models and meta-data,than that in a single-node DMBS,in which query optimization is already an NP-hard problem.Learned query optimizers(mainly in the single-node DBMS)receive attention due to its capability to capture data distributions and flexible ways to avoid hard-craft rules in refinement and adaptation to new hardware.In this paper,we focus on extensions of learned query optimizers to distributed DBMSs.Specifically,we propose one possible but general architecture of the learned query optimizer in the distributed context and highlight differences from the learned optimizer in the single-node ones.In addition,we discuss the challenges and possible solutions. 展开更多
关键词 distributed query processing query optimization learned query optimizer
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A method for improving graph queries processing using positional inverted index (P.I.I) idea in search engines and parallelization techniques 认领 引用 被引量：2
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作者 Hamed Dinari Hassan Naderi 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第1期150-159,共10页
The idea of positional inverted index is exploited for indexing of graph database. The main idea is the use of hashing tables in order to prune a considerable portion of graph database that cannot contain the answer s... The idea of positional inverted index is exploited for indexing of graph database. The main idea is the use of hashing tables in order to prune a considerable portion of graph database that cannot contain the answer set. These tables are implemented using column-based techniques and are used to store graphs of database, frequent sub-graphs and the neighborhood of nodes. In order to exact checking of remaining graphs, the vertex invariant is used for isomorphism test which can be parallel implemented. The results of evaluation indicate that proposed method outperforms existing methods. 展开更多
关键词 graph query processing frequent subgraph graph mining data mining positional inverted index
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Bounded Evaluation:Querying Big Data with Bounded Resources 认领 引用
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作者 Yang Cao Wen-Fei Fan Teng-Fei Yuan 《International Journal of Automation and computing》 CSCD 2020年第4期502-526,共25页
This work aims to reduce queries on big data to computations on small data,and hence make querying big data possible under bounded resources.A query Q is boundedly evaluable when posed on any big dataset D,there exist... This work aims to reduce queries on big data to computations on small data,and hence make querying big data possible under bounded resources.A query Q is boundedly evaluable when posed on any big dataset D,there exists a fraction DQ of D such that Q(D)=Q(DQ),and the cost of identifying DQ is independent of the size of D.It has been shown that with an auxiliary structure known as access schema,many queries in relational algebra(RA)are boundedly evaluable under the set semantics of RA.This paper extends the theory of bounded evaluation to RAaggr,i.e.,RA extended with aggregation,under the bag semantics.(1)We extend access schema to bag access schema,to help us identify DQ for RAaggr queries Q.(2)While it is undecidable to determine whether an RAaggr query is boundedly evaluable under a bag access schema,we identify special cases that are decidable and practical.(3)In addition,we develop an effective syntax for bounded RAaggr queries,i.e.,a core subclass of boundedly evaluable RAaggr queries without sacrificing their expressive power.(4)Based on the effective syntax,we provide efficient algorithms to check the bounded evaluability of RAaggr queries and to generate query plans for bounded RAaggr queries.(5)As proof of concept,we extend PostgreSQL to support bounded evaluation.We experimentally verify that the extended system improves performance by orders of magnitude. 展开更多
关键词 Bounded evaluation resource-bounded query processing effective syntax access schema boundedness
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A Grammar Analysis Model for the Unified Multimedia Query Language 认领 引用
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作者 Zhong-Sheng Cao Zong-Da Wu Yuan-Zhen Wang 《Journal of Electronic Science and Technology of China》 2008年第3期317-322,共6页
The unified multimedia query language （UMQL） is a powerful general-purpose multimedia query language, and it is very suitable for multimedia information retrieval. The paper proposes a grammar analysis model to impl... The unified multimedia query language （UMQL） is a powerful general-purpose multimedia query language, and it is very suitable for multimedia information retrieval. The paper proposes a grammar analysis model to implement an effective grammatical processing for the language. It separates the grammar analysis ofa UMQL query specification into two phases： syntactic analysis and semantic analysis, and then respectively uses Backus-Naur form （EBNF） and logical algebra to specify both restrictive grammar rules. As a result, the model can present error guiding information for a query specification which owns incorrect grammar. The model not only suits well the processing of UMQL queries, but aLso has a guiding significance for other projects concerning query processings of descriptive query languages. 展开更多
关键词 Grammar analysis query language query processing unified multimedia query language
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Hash-area-based data dissemination protocol in wireless sensor networks 认领 引用 被引量：2
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作者 王田 王国军 +1 位作者 过敏意 贾维嘉 《Journal of Central South University of Technology》 2008年第3期392-398,共7页
HashQuery,a Hash-area-based data dissemination protocol,was designed in wireless sensor networks. Using a Hash function which uses time as the key,both mobile sinks and sensors can determine the same Hash area. The se... HashQuery,a Hash-area-based data dissemination protocol,was designed in wireless sensor networks. Using a Hash function which uses time as the key,both mobile sinks and sensors can determine the same Hash area. The sensors can send the information about the events that they monitor to the Hash area and the mobile sinks need only to query that area instead of flooding among the whole network,and thus much energy can be saved. In addition,the location of the Hash area changes over time so as to balance the energy consumption in the whole network. Theoretical analysis shows that the proposed protocol can be energy-efficient and simulation studies further show that when there are 5 sources and 5 sinks in the network,it can save at least 50% energy compared with the existing two-tier data dissemination(TTDD) protocol,especially in large-scale wireless sensor networks. 展开更多
关键词 wireless sensor networks Hash function data dissemination query processing mobile sinks
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Monitoring Median Queries over Moving Objects 认领 引用
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作者 许浒 卢炎生 李支成 《Journal of Southwest Jiaotong University(English Edition)》 2010年第4期326-332,共7页
The k-median problem has attracted a number of researchers. However,few of them have considered both the dynamic environment and the issue of accuracy. In this paper,a new type of query is studied,called continuous me... The k-median problem has attracted a number of researchers. However,few of them have considered both the dynamic environment and the issue of accuracy. In this paper,a new type of query is studied,called continuous median monitoring （CMM） query. It considers the k-median problem under dynamic environment with an accuracy guarantee. A continuous group nearest neighbor based （CGB） algorithm and an average distance medoid （ADM） algorithm are proposed to solve the CMM problem. ADM is a hill climbing schemed algorithm and achieves a rapid converging speed by checking only qualified candidates. Experiments show that ADM is more efficient than CGB and outperforms the classical PAM （partitioning around medoids） and CLARANS （clustering large applications based on randomized search） algorithms with various parameter settings. 展开更多
关键词 Spatial databases Query processing Nearest neighbor query k-Median problem
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