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The 9th International Conference for Young Computer Scientists(第九届国际青年计算机大会)

作者： Tian Xia Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China MOE Beijing 100872 China School of Information Resource Management Renmin University of China. Beijing 100872 China

The edit distance between two given strings X and Y is the minimum number of edit operations that transform X into Y. In ordinary course, string editing is based on character insert, delete, and substitute operations. It has been suggested that extending this model with block edits would be useful in applications such as DNA sequence comparison and sentence similarity computation. However, the existing algorithms have generally focused on the normalized edit distance, and seldom of them consider the block swap operations at a higher level. In this paper, we introduce an extended edit distance algorithm which permits insertions, deletions, and substitutions at character level, and also permits block swap operations. Experimental results on randomly generated strings verify the algorithm's rationality and efficiency. The main contribution of this paper is that we present an algorithm to compute the lowest edit cost for string transformation with block swap in polynomial time, and propose a breaking points selection algorithm to improve the computation speed.

关键词： Edit distance edit operation block swap string matching.

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Clustering XML retrieval results based on hybrid similarity

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Journal of Computational Information Systems 2008年第3期4卷 1323-1330页

作者： Wan, Changxuan Yu, Hong School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Jiangxi University of Finance and Economics Nanchang 330013 China

With the unceasing growth of XML data in World Wide Web, XML document retrieval and clustering retrieval results are confronted with both challenges and opportunities. One of the challenges is how to improve the quality of XML retrieval results. Firstly, according to the features of XML documents, a method of modeling XML retrieval result documents is brought forward, which integrates both structural semantic features and content information of XML documents. Then, a measure method to compute similarity, including structural semantic similarity and keywords similarity, between retrieval result documents is suggested;and a strategy named Item Frequency in Cluster-Inverse Cluster Frequency to extract labels from result clusters is presented. Experiments indicate that the clustering quality for XML retrieval results based on hybrid similarity is obviously better than the one only based on content similarity.

关键词： XML

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Automatic detection of integer sign vulnerabilities

Automatic detection of integer sign vulnerabilities

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International Conference on Information and Automation (ICIA)

作者： Bin Liang Hui Liu Wenchang Shi Zhiyong Shan Renmin University of China Beijing CN College of Computer Science and Technology Huazhong University of Science and Technology Wuhan China Key Laboratory of Data Engineering and Knowledge Engineering (Renmin University of China) MOE Beijing 100872 China

The integer sign vulnerability is a comparatively new and subtle type of vulnerabilities, they can compromise system security. Especially, if a sign vulnerability occurs in operating system kernel, it may result in very serious invalid read/write operations to kernel memory area. Unfortunately, little attention has been paid to static detecting them automatically. This paper presents a novel approach to detecting sign vulnerabilities in Linux kernel using type qualifier technique. We introduce three pairs of type qualifier and corresponding lattices to identify some key kernel data and relationships between them. Based on an extended type inference tool, we are able to effectively detect known and unknown sign vulnerabilities from elaborately preprocessed Linux kernel files. Our experiences demonstrate that type qualifier technique can be applied to detect sign vulnerabilities effectively.

关键词： Kernel Linux Lattices Indexes Arrays Security Buffer overflow

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MRST-- An Efficient Monitoring Technology of Summarization on Stream data

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Journal of Computer Science & Technology 2007年第2期22卷 190-196页

作者：樊小泊解婷婷李翠平陈红 School of Information Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering MOE Beijing 100872 China

Monitoring on data streams is an efficient method of acquiring the characters of data stream. However the available resources for each data stream are limited, so the problem of how to use the limited resources to process infinite data stream is an open challenging problem. In this paper, we adopt the wavelet and sliding window methods to design a multi-resolution summarization data structure, the Multi-Resolution Summarization Tree （MRST） which can be updated incrementally with the incoming data and can support point queries, range queries, multi-point queries and keep the precision of queries. We use both synthetic data and real-world data to evaluate our algorithm. The results of experiment indicate that the efficiency of query and the adaptability of MRST have exceeded the current algorithm, at the same time the realization of it is simpler than others.

关键词： Haar wavelet sliding window stream data

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Indexing Future Trajectories of Moving Objects in a Constrained Network

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Journal of Computer Science & Technology 2007年第2期22卷 245-251页

作者：陈继东孟小峰 School of Information Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Beijing 100872 China

Advances in wireless sensor networks and positioning technologies enable new applications monitoring moving objects. Some of these applications, such as traffic management, require the possibility to query the future trajectories of the objects. In this paper, we propose an original data access method, the ANR-tree, which supports predictive queries. We focus on real life environments, where the objects move within constrained networks, such as vehicles on roads. We introduce a simulation-based prediction model based on graphs of cellular automata, which makes full use of the network constraints and the stochastic traffic behavior. Our technique differs strongly from the linear prediction model, which has low prediction accuracy and requires frequent updates when applied to real traffic with velocity changing frequently. The data structure extends the R-tree with adaptive units which group neighbor objects moving in the similar moving patterns. The predicted movement of the adaptive unit is not given by a single trajectory, but instead by two trajectory bounds based on different assumptions on the traffic conditions and obtained from the simulation. Our experiments, carried on two different datasets, show that the ANR-tree is essentially one order of magnitude more efficient than the TPR-tree, and is much more scalable.

关键词： database spatial database access methods moving objects

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Capability enhanced trust evaluation model for Web services

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Jisuanji Xuebao/Chinese Journal of Computers 2008年第8期31卷 1471-1477页

作者： Li, Hai-Hua Du, Xiao-Yong Tian, Xuan Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China Beijing 100872 China School of Information Renmin University of China Beijing 100872 China School of Information Science and Technology Beijing Forestry University Beijing 100083 China

In open environment, an effective trust mechanism should be built to ensure transaction safety. But current trust evaluation approaches solely based on the certificate or feedback are inaccurate and ineffective. Thus, referring to the social trust models, this paper presents a capability enhanced method to improve the accuracy of evaluating trustworthiness. Based on it, this paper also designs a trust evaluation model ServTrust that naturally provides a solution to the trust problem. Compared with current feedback based approaches, simulation experimental results show the effectiveness of the proposed model in trust evaluating.

关键词： Web services

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Structural Join and Staircase Join Algorithms of Sibling Relationship

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Journal of Computer Science & Technology 2007年第2期22卷 171-181页

作者：万常选刘喜平 School of Information Technology Jiangxi University of Finance and Economics Nanchang 330013 China Jiangxi Key Laboratory of Data and Knowledge Engineering Nanchang 330013 China

The processing of XML queries can result in evaluation of various structural relationships. Efficient algorithms for evaluating ancestor-descendant and parent-child relationships have been proposed. Whereas the problems of evaluating preceding-sibling-following-sibling and preceding-following relationships are still open. In this paper, we studied the structural join and staircase join for sibling relationship. First, the idea of how to filter out and minimize unnecessary reads of elements using parent＇s structural information is introduced, which can be used to accelerate structural joins of parent-child and preceding-sibling-following-sibling relationships. Second, two efficient structural join algorithms of sibling relationship are proposed. These algorithms lead to optimal join performance： nodes that do not participate in the join can be judged beforehand and then skipped using B^＋-tree index. Besides, each element list joined is scanned sequentially once at most. Furthermore, output of join results is sorted in document order. We also discussed the staircase join algorithm for sibling axes. Studies show that, staircase join for sibling axes is close to the structural join for sibling axes and shares the same characteristic of high efficiency. Our experimental results not only demonstrate the effectiveness of our optimizing techniques for sibling axes, but also validate the efficiency of our algorithms. As far as we know, this is the first work addressing this problem specially.

关键词： XML query processing sibling relationship structural join staircase join

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Optimization framework for distributed clustering scheme in wireless sensor networks

Optimization framework for distributed clustering scheme in ...

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SNPD 2007: 8th ACIS International Conference on Software engineering, Artificial Intelligence, Networking, and Parallel/Distributed Computing

作者： Yongxuan, Lai Xiaobo, Fan Hong, Chen Tingting, Xie School of Information Renmin University of China Beijing Key Laboratory of Data Engineering and Knowledge Engineering MOE

ISBN: (纸本)0769529097

Recently there have been growing interests in the applications of wireless sensor networks. Innovative techniques that improve energy efficiency to prolong the network lifetime are highly required. Clustering is an effective topology control approach and data gathering protocol in wireless sensor networks. In this paper, we propose a novel optimization framework called MICA (MICa Adjustments) for clustering scheme in wireless sensor networks. MICA takes the cluster as a whole, and dynamically adjusts the clusters according to the real-lime workload of the local clusters to balance energy consumption among clusters. The adjustments can also deal with link failures. Simulation results show that MICA can be easily embedded into existing clustering schemes to balance the energy consumptions among the clusters, and to prolong the lifetime of wireless sensor networks. © 2007 IEEE.

关键词： Wireless sensor networks

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A WSMO-based semantic web services discovery framework in heterogeneous ontologies environment

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2nd International Conference on knowledge Science, engineering and Management, KSEM 2007

作者： Haihua, Li Xiaoyong, Du Xuan, Tian School of Information Renmin University of China China Key Laboratory of Data Engineering and Knowledge Engineering MOE

ISBN: (纸本)9783540767183

Nowadays, WSMO (Web Service Modeling Ontology)1 has received great attention of academic and business communities, since its potential to achieve dynamic and scalable infrastructure for web services is extracted. Therefore, we design an ontology-based Semantic Web Services (SWSs) discovery framework based on WSMO so as to searching dynamically web services located at different nodes. Also, we provide several SWSs matching techniques based on this framework. © Springer-Verlag Berlin Heidelberg 2007.

关键词： Semantic Web

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CLASCN： Candidate Network Selection for Efficient Top-κ keyword Queries over databases

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Journal of Computer Science & Technology 2007年第2期22卷 197-207页

作者：张俊彭朝晖王珊聂惠静 School of Information Renmin University of China Beijing 100872 China Key Laboratory of Data Engineering and Knowledge Engineering Ministry of Education Beijing 100872 China Computer Science and Technology College Dalian Maritime University Dalian 116026 China

keyword Search Over Relational databases （KSORD） enables casual or Web users easily access databases through free-form keyword queries. Improving the performance of KSORD systems is a critical issue in this area. In this paper, a new approach CLASCN （Classification, Learning And Selection of Candidate Network） is developed to efficiently perform top-κ keyword queries in schema-graph-based online KSORD systems. In this approach, the Candidate Networks （CNs） from trained keyword queries or executed user queries are classified and stored in the databases, and top-κ results from the CNs are learned for constructing CN Language Models （CNLMs）. The CNLMs are used to compute the similarity scores between a new user query and the CNs from the query. The CNs with relatively large similarity score, which are the most promising ones to produce top-κ results, will be selected and performed. Currently, CLASCN is only applicable for past queries and New All-keyword-Used （NAU） queries which are frequently submitted queries. Extensive experiments also show the efficiency and effectiveness of our CLASCN approach.

关键词： relational database keyword search top-κ query candidate network

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