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Efficient Computation of Reverse Skyline on data Stream

Efficient Computation of Reverse Skyline on Data Stream

The Second International Joint Conference on Computational Science and Optimization(CSO 2009)(2009 国际计算科学与优化会议)

作者： Ling Zhu Cuiping Li Hong Chen School of Information Renmin University of China Key Lab of Data Engineering and Knowledge Engineering of MOE

Reverse Skyline Queries have been proved very useful in business location, environmental monitoring and some other applications. In this paper, we consider reverse skyline queries processing on data stream, which provides continuous, high-speed data elements. Specifically, we consider the latest objects in the sliding window. The challenge is that it is difficult to maintain a multidimensional index (for example, R-tree) in a dynamic dataset. Focusing on this challenge, we propose an algorithm with a DC-Tree as index and effective pruning methods to reduce the search space of query processing and the cost of index maintaining. Extensive experiments show that our algorithms are efficient and effective for on-line reverse skyline query.

关键词： Monitoring Query processing Costs data engineering knowledge engineering Multidimensional systems

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Incremental computation for MEDIAN cubes in what-if analysis

Incremental computation for MEDIAN cubes in what-if analysis

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

作者： Xiao, Yanqin Zhang, Yansong Wang, Shan Chen, Hong Key Laboratory of Data Engineering and Knowledge Engineering Renmin University of China MOE Beijing 100872 China School of Information Renmin University of China Beijing 100872 China Computer Center Hebei University Baoding Hebei 071002 China Department of Computer Science Harbin Finance College Harbin 150030 China

ISBN: (纸本)9783642006715

What-if analysis is an important type of DSS analysis processing procedure. It analyzes hypothetical scenarios based on historical data. The data cube view must be updated when the what-if condition is changed. Since source data must be kept in order to compute the new aggregate value when new tuples are inserted or deleted, in what-if analysis, incrementally computing a data cube for holistic aggregation functions is a difficult problem. In this paper, we adopt delta cube strategy and work area technique to incrementally compute data cube for MEDIAN function. The size of work area has important influence on the efficiency of the incremental computing. This paper optimizes the size of work area based on the number and the cardinality of dimension attributes of the cuboid. Performance study shows that our algorithms are effective over large databases. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Geometry

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Efficient incremental computation of CUBE in multiple versions what-if analysis

Efficient incremental computation of CUBE in multiple versio...

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Joint International Conference on Advances in data and Web Management, APWeb/WAIM 2009

ISBN: (纸本)9783642006715

What-if analysis is an important method to analyze the hypothetical scenarios based on the historical data. It provides useful information for the decision- maker. Multiple versions are critical to what-if analysis. In this paper, we analyze the problem of multiple versions data processing and the incremental computation of cubes in what-if analysis, proposing a strategy to process multiple versions of what-if data. Our solution can adopt different data processing methods according to the type of aggregate functions, the efficiency of multiple versions data processing is improved. Furthermore, we proposes an algorithm of incremental computation of CUBE for max(min) function to reduce the access time of fact table, and the experimental results showed that the performance is improved about 10%. © Springer-Verlag Berlin Heidelberg 2009.

关键词： Decision making

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Interference and power constrained Broadcasting and Multicasting in wireless ad hoc networks with directional antennas

Interference and power constrained Broadcasting and Multicas...

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IEEE Internatonal Conference on Mobile Adhoc and Sensor Systems (MASS)

作者： Zheng Li Deying Li Ming Liu Key Laboratory of Data Engineering and Knowledge Engineering MOE School of Information Renmin University of China China School of Computer Science and Engineering University of Electronic Science and Technology Chengdu China

ISBN: (纸本)9781424451142

Broadcasting/Multicasting problems have been well studied in wireless ad hoc networks. However, only a few approaches take into account the low interference and energy efficiency as the optimization objective simultaneously. In this paper, we study the interference and power constrained broadcast/multicast and the delay-bounded interference and power constrained broadcast/multicast routing problems in wireless ad hoc networks using directional antennas. We propose an approximation and a heuristic algorithm for the two problems, respectively. Importantly, motivated by the study of above optimization problems, we propose approximation schemes for two multi-constrained directed Steiner tree problems, respectively. Broadcast/Multicast message by using the trees found by our algorithms tend to have less channel collisions and higher network throughput. The theoretical results are corroborated by simulation studies.

关键词： Interference constraints Broadcasting Mobile ad hoc networks Directional antennas Multicast algorithms Energy efficiency Routing Approximation algorithms Heuristic algorithms Throughput

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Assessing the influence probability between objects: A random walker approach

Assessing the influence probability between objects: A rando...

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IEEE Symposium on Computational Intelligence and data Mining (CIDM)

作者： Pei Li Zhixu Li Jun He Xiaoyong Du Hongyan Liu Key Laboratories of Data Engineering and Knowledge Engineering MOE China & School of Information Renmin University of China Beijing China Department of Management Science and Engineering Tsinghua University Beijing China

Influence between objects needs to be assessed in many applications. Lots of measures have been proposed, but a domain-independent method is still expected. In this paper, we give a probabilistic definition of influence based on the random walker model on graphs. Two approaches, linear systems method and Basic InfRank algorithm, are shown and return equal results, but Basic InfRank is more efficient by iterative computation. Two variants on bipartite graphs and star graphs are discussed. Experiments show InfRank algorithms have good accuracy, fast convergent rate and high performance.

关键词： data engineering knowledge engineering Iterative algorithms Attenuation measurement Helium knowledge management engineering management Linear systems Iterative methods Bipartite graph

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Malicious Web Pages Detection Based on Abnormal Visibility Recognition

Malicious Web Pages Detection Based on Abnormal Visibility R...

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International Conference on E-Business and Information System Security, EBISS

作者： Bin Liang Jianjun Huang Fang Liu Dawei Wang Daxiang Dong Zhaohui Liang Key Laboratory of Data Engineering and Knowledge Engineering MOE Renmin University of China Beijing China School of Information Renmin University of China Beijing China Renmin University of China Beijing CN

In recent years, Web sites have already become the attackers' main target. When attackers embed malicious code in the Web pages, they generally change the display mode of the corresponding HTML tags to make the display effect of malicious code invisible or almost invisible to the browser users. In this paper, the concept of abnormal visibility is proposed to describe the display feature setting of malicious code embedded. According to the concept, a malicious code detection method based on abnormal visibility recognition is designed and a prototype system is implemented. Compared to traditional methods and systems, the method has higher efficiency and less maintenance cost. Besides, a special-purpose JavaScript interpreter is implemented to get the execution output of browser-end scripts that are often used to generate malicious code dynamically by attackers. Experiments show that this system can detect most of the malicious Web pages efficiently and at the same time locate the malicious code in the source code accurately.

关键词： Web pages Displays Java Prototypes HTML Costs Invasive software Fingerprint recognition laboratories data engineering

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Static vulnerabilities detection method based on security state tracing and checking

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Jisuanji Xuebao/Chinese Journal of Computers 2009年第5期32卷 899-909页

作者： Liang, Bin Hou, Kan-Kan Shi, Wen-Chang Liang, Zhao-Hui School of Information Renming University of China Beijing 100872 China MOE Key Laboratory of Data Engineering and Knowledge Engineering Beijing 100872 China

The main problem of existing static vulnerability detection methods based source code analysis is their high false positive and false negative rates. One main reason is lack of accurate and effective identification and analysis of security-related program elements, e.g. data validation checking, tainted data source, etc. A static vulnerability detection method based on data security state tracing and checking is proposed. In this method, the state space of state machine model is extended;the security state of a variable is identified by a vector that may correspond to multiple security-related properties rather than by a single property;Fine-grained state transition is provided to support accurate recognition of program security-related behaviors;The recognition of validation checking is introduced in vulnerability state machine to reduce false positives;and a systematic discrimination mechanism for tainted data is constructed to prevent false negatives result from neglecting tainted data sources. The experimental results of a prototype system show that this method can effectively detect buffer overflow and other type's vulnerabilities in software systems, and with obviously lower false positive than existing mainstream static detection methods and avoid some serious false negatives of these methods.

关键词： Static analysis

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A new dynamic hash index for flash-based storage

A new dynamic hash index for flash-based storage

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9th International Conference on Web-Age Information Management, WAIM 2008

作者： Xiang, Li Zhou, Da Meng, Xiaofeng School of Information Renmin University of China Key Laboratory of Data Engineering and Knowledge Engineering MOE

ISBN: (纸本)9780769531854

Compared with traditional magnetic disks, Flash memory has many advantages and has been used as external storage media for a wide spectrum of electronic devices (such as PDA, MP3, Digital Camera and Mobile Phone) in recent years. As the capacity increases and price drops, it looks like a perfect alternative for magnetic disks. However, due to hardware limitations of flash memory, techniques including storage subsystem and indexing originally designed for magnetic disks can not run smoothly in a flash memory without any modification. In this paper we explore problems of indexing flash-resided data and present a new dynamical hash index for flash memory in two schemas. The analysis and experimental results validate the efficiency of our design. © 2008 IEEE.

关键词： Flash memory

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基于Web Services的信息系统的实施研究

基于Web Services的信息系统的实施研究

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第15届海峡两岸信息管理发展与策略学术研讨会(2009)

作者： Zuo Meiyun 左美云 Wang Shijuan 王世娟 In formation School and Key Laboratory of Data Engineering and Knowledge Engineering MOE Renmin Univ 中国人民大学信息学院数据工程与知识工程教育部重点实验室北京

基于Web Services的信息系统将会是今后信息系统建设的一种重要模式。论文在对23个实施基于WebServices的信息系统的二手资料分析的基础上，归纳了基于Web Services的信息系统的类型、实施策略和实施过程。

关键词：企业管理信息系统控制策略网络服务

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LOB: Bucket based index for range queries

LOB: Bucket based index for range queries

引用

9th International Conference on Web-Age Information Management, WAIM 2008

作者： Wang, Jieping Du, Xiaoyong Key Laboratory of Data Engineering and Knowledge Engineering MOE Beijing 100872 China School of Information Renmin University of China Beijing 100872 China

ISBN: (纸本)9780769531854

database-as-a-Service is a promising data management paradigm in which data is encrypted before being sent to the untrusted server. Efficient querying on encrypted data is a performance critical problem which has various solutions, among which bucket based index is an effective and flexible one. In previous research some metrics are proposed to measure security and efficiency. In this paper, we illustrate by example the limitations of these metrics and introduce a new security metric based on probability distribution variance and efficiency metric based on overlapping ratio. Based on these metrics we propose a local overlapping bucket algorithm (LOB) with time complexity of O(nlogn), where n represents the cardinality of the table. Experiments on synthetic and real dataset show that our algorithm can achieve higher security by trading off efficiency. © 2008 IEEE.

关键词： Information management

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