用多用户多窗口处理多维视图动态选择 - 薛永生; 林子雨; 段江娇; 吕晓华; 张伟
多维视图动态维护是数据仓库领域当前研究的一个热点 随着数据仓库的普及 ,将有越来越多的各种类型的用户使用OLAP工具满足各自特定的分析需求 现有的各种视图选择方法没有考虑不同类型用户的特点 ,从而存在一些缺陷 提出多用户多窗口方法 ,充分考虑用户的差异 ,利用单个用户在查询时的相对有规律性 ,为用户划分级别 ,并为每个用户设置相应级别的用户视图窗口 ,从而合理地利用了系统有限的资源 ,提高了查询响应速度 ,也保证了特殊用户对查询性能的特殊需求 ;给出了相关的定义和MUMW算法 ,并阐述了多用户多窗口方法的优点。Dynamic selection of materialized views of multi-dimensional data is one of the most researched aspects in the field of data warehouse; With the increasing use of data warehouse, there will be accordingly more and more different kinds of users making use of OLAP tools to complete their analytical work; The existing met hods being used to select views do not take into ccount the characteristic of various kinds of users, and therefore have some defects; A multi-users and multi-windows method is presented here, which considerst he...
实时主动数据仓库中的变化数据捕捉研究综述 - 林子雨; 杨冬青; 宋国杰; 王腾蛟
实时主动数据仓库是数据仓库的最新发展阶段和未来发展趋势,它为企业提供了对战略决策和战术决策的双重支持.实时主动数据仓库中包含两类数据,即实时数据和非实时数据,相应地,需要两种不同类型的变化数据捕捉方法,即支持实时变化数据捕捉的方法和普通的(不支持实时的)变化数据捕捉方法.结合在该领域的研究经验,对实时主动数据仓库中可以使用的多种变化数据捕捉方法进行了系统地论述,并比较各种方法的应用条件、优点、缺点和适用场合。Real-time active data warehouse is the most recent stage in the evolution history of data warehouses．It supports both strategic decision and tactic decision，which will bring great benefits to organizations．There are two types of data existing in real-time active data warehouses，i．e．，real-time data and non-real-time data．Accordingly，change data capture methods are classified into tWO kinds，including those supporting real-time change data capture and those not supporting real-time change data capture．Based on extensive research work in this field，those change data capture methods are systematically discussed，which may meet the requirements in real-time active data warehouses．
实时主动数据仓库中面向需求的实时数据集成方法研究 - 林子雨; 杨冬青; 宋国杰; 王腾蛟
实时数据集成是实时主动数据仓库研究领域的一个重要问题。现有的研究成果都是从技术角度出发，而并没有考虑具体的商务应用需求。而在大型商务应用中，即使采用过滤规则只捕捉感兴趣的变化数据，也会产生大量的数据集成工作，从而导致不必要的沉重系统开销，同时还很有可能出现系统响应缓慢和用户需求无法得到满足等情况。本文从应用角度出发，提出了实时主动数据仓库中面向需求的实时数据集成方法，包括被频繁请求的数据的实时集成、满足突发请求的实时数据集成和由用户决定的实时数据集成。针对不同的商务需求，采用不同的数据集成策略，可以很好地满足不同类型的应用需求。Real-time data integration is a very important aspect in the field of real-time active data warehouse. Almost all the available research work now is from a technological point of view instead of an application angle. While in the real-world business application, a large amount of real-time data integration needs to be done even with the help of change data capture technology to integrate only the interesting part of the data from the data source, which will usually lead to the deteriorated system performance and fail to satisfy the business requirement in some cases. From an application angle, we here propose...
实时主动数据仓库中多维数据实视图的选择 - 林子雨; 杨冬青; 宋国杰; 王腾蛟; 唐世渭
通过基于主动决策引擎日志的数据挖掘来找到分析规则的CUBE 使用模式,从而为多维数据实视图选择算法提供重要依据;在此基础上设计了3A 概率模型,并给出考虑CUBE 受访概率分布的视图选择贪婪算法PGreedy(probability greedy), 以及结合视图挽留原则的视图动态调整算法. 实验结果表明, 在实时主动数据仓库环境下,PGreedy 算法比BPUS(benefit per unit space)算法具有更好的性能. In this paper, data mining based on the log of active decision engine is introduced to find the CUBE using pattern of analysis rules, which can be used as important reference information for materialized views selection. Based on it, a 3A probability model is designed, and the greedy algorithm, called PGreedy (probability greedy), is proposed, which takes into account the probability distribution of CUBE. Also view keeping rule is adopted to achieve better performance for dynamic view adjusting. Experimental results show that PGreedy algorithm can achieve better performance...
用基于移动均值的索引实现时间序列相似查询 - 林子雨; 杨冬青; 王腾蛟
提出了基于移动均值的索引来解决子序列匹配中的"(-查询"问题;提出并证明了基于移动均值的缩距定理和缩距比关系定理,后者具有很好的"裁减"能力,可以在相似查询时淘汰大部分不符合条件的候选时间序列,从而达到快速相似查找的目的;引入了由Jagadish 等人提出的BATON*-树,并在此基础上适当修改,建立了MABI索引,极大地加快了相似查询过程;最后,在一个股票交易数据集上进行了实验,证明了MABI索引的良好性能.In this paper, a method called MABI (moving average based indexing) is proposed to effectively deal with the issue of (-search query in subsequence matching. Two important theorems, distance reduction theorem and DRR(distance reduction rate) relation theorem, are proposed here to be as the basis of MABI. DRR relation theorem has strong capability in "pruning" those unqualified candidate sequences so as to achieve of fast similarity search. Furthermore, by modifying BATON* introduced by Jagadish, et al., a multi-way balanced tree structure is introduced, to construct the index from time series, which significantly speeds up the similarity search. Extensive experiments...
实视图选择研究 - 林子雨; 杨冬青; 王腾蛟; 宋国杰
定义了数据仓库领域的视图选择问题,并讨论了与该问题相关的代价模型、收益函数、代价计算、约束条件和视图索引等内容;介绍了3大类视图选择方法,即静态方法、动态方法和混合方法,以及各类方法的代表性研究成果;最后展望未来的研究方向.Definition of view selection issue in the field of data warehouses is presented, followed by the discussion of related problems, such as cost model, benefit function, cost computation, restriction condition, view index, etc. Then three categories of view selection methods, namely, static, dynamic and hybrid methods are discussed. For each method, some representative work is introduced. Finally some future trends in this area are discussed.
DB&IR系统研究综述 - 林子雨; 左思强; 赖永炫; 张东站
介绍了从DB、IR到DB&IR的发展历程；阐述了DB&IR系统的设计考虑因素；讨论了DB&IR系统的体系架构设计问题；介绍了DB&IR系统所采用的基于关键词的查询技术；最后总结并展望未来的研究方向。The development process from DB, IR to DB&IR is presented first, followed by the detailed description of the consideration factors for the design and architecture of DB&IR system. Then keyword search in DB&IR system is discussed. Finally, some future trends in this area are discussed.
基于关系数据库的关键词查询 - 林子雨; 杨冬青; 王腾蛟; 张东站
介绍了基于关系数据库的关键词查询问题的研究背景;阐述了解决该问题的两大类方法,即基于数据图的方法和基于模式图的方法,并详细介绍了各种方法的原理以及各自的优缺点;最后展望了未来的研究方向。First, the research background of keyword search over relational databases is presented and is followed by a detailed description of two solutions to this problem, i.e., data graph based and schema graph based methods, and a discussion of the principles, advantages and disadvantages of these methods is also mentioned. Finally, some future trends in this area are discussed.
云数据库研究 - 林子雨; 赖永炫; 林琛; 谢怡; 邹权
随着云计算的发展,云数据库的重要性和价值日益显现;介绍了云数据库的特性、影响、相关产品;详细讨论了云数据库领域的研究问题,包括数据模型、系统体系架构、事务一致性、编程模型、数据安全、性能优化和测试基准等;最后讨论了云数据库的未来研究方向。With the recent development of cloud computing, the importance of cloud databases has been widely acknowledged. Here the features, influence and related products of cloud databases are first discussed. Then research issues of cloud databases are presented in detail, which include data model, architecture, consistency, programming model, data security, performance optimization, benchmark, and so on. Finally, some future trends in this area are discussed.
基于关系数据库的top-k聚合关键词查询 - 张东站; 苏志锋; 林子雨; 薛永生
基于关系数据库的关键词查询,使得用户在不需要掌握结构化查询语言和数据库模式的情况下,可以方便的进行关系数据库查询.给定一个关键词查询,已有的方法通过数据库中的主外键关联,查询得到包含关键词的元组集合.但是,在很多实际应用中,元组集合的聚合结果对用户更有价值;研究了基于关系数据库的top-k聚合关键词查询,提出了基于递归的聚合单元枚举算法—RFS.为了获得更好的查询性能, 设计了新的排序方法、二维索引和快速搜索算法—OQS,从而可以高效地枚举top-k个聚合单元;在不同的数据集上进行了大量的实验,实验结果表明OQS算法具有良好的查询性能.Keyword search over relational databases allows users to search databases without any knowledge of database schema and query languages. Given a keyword query, the existing approaches find individual tuples which match a set of query keywords based on primary-foreign-key relationships in databases. However, it is more useful for users to get the aggregation result of tuples in many real applications, and those existing methods cannot be used to deal with such issue. Therefore, this paper is focused on the problem of top-k aggregation keyword search over relational databases. Here recursion-based full search algorithm, i.e., RFS, is proposed to get...
An Approach for Identifying Cytokines Based on a Novel Ensemble Classifier - Quan Zou; Zhen Wang; Xinjun Guan; Bin Liu; Yunfeng Wu; Ziyu Lin; 林子雨
Copyright 2013 Quan Zou et al. his is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Synthesis of Structurally Simple Supervisors Enforcing Generalized Mutual Exclusion Constraints in Petri Nets - Li, Z. W.; Yan, M. M.; Zhou, M. C.; 黎忠文
Generalized mutual exclusion constraints (GMECs) are a typical class of specifications for the supervisory control of discrete event systems in a Petri net formalism. This paper classifies the given constraints into elementary and dependent ones according to the linear dependency of their characteristic transition vectors that indicate the token count change of the concerned places. The dependent constraints are further divided into strongly and weakly dependent ones. A constraint is usually enforced by explicitly adding a monitor to a plant model. This research develops the conditions under which a dependent constraint is enforced due to the enforcement of the elementary...
Formulas of Gauss-Ostrogradskii type on real Finsler manifolds - Li Zhiwei; Zhong Chunping; 黎忠文
This article generalizes the formulas of Gauss-Ostrogradskii type for semibasic vector fields from Riemannian manifolds to real Finsler manifolds and obtains some formulas of Gauss-Ostrogradskii type for Finsler vector fields which are expressed in terms of the vertical and horizontal derivatives of the Cartan connection in real Finsler manifolds.
A cross-authentication model and implementation - Li, Z. W.; Chen, Q.; Xiang, Y.; 黎忠文
The current status is that there is coexistence of different authentication mechanisms in heterogeneous domains. We have noticed that the there are little work has been cone in cross-authentication for heterogeneous domains. In this paper, we target on this problem, and propose a cross-authentication model for heterogeneous domains on active networks. We implement our model with the method of system redundancy. We make the simulation of active networks under Windows environment. Moreover, we give out the security proof of our model. Our system implements mutual entity authentication among heterogeneous domains based on PKI and ID-PKC. The theoretical analysis and the...
Checkpointing schemes for Grid workflow systems - Li, Z. W.; Xiang, Y.; 黎忠文
One of the major challenges in wide use of Grid workflow systems is fault tolerance and avoidance. Checkpointing schemes provide a way of fault detection and recovery. In our research, we focus on the performance optimization of checkpointing schemes and dynamic voltage scaling (DVS) for Grid workflow systems. We propose offline checkpointing schemes with DVS and online adaptive checkpointing schemes that dynamically adjust the checkpointing intervals by using store checkpoints and compare checkpoints. When combined with DVS, offline adaptive checkpointing schemes not only are fault tolerant but also lead to reduce average execution time of tasks. These schemes can efficiently...