复合滑动窗口连接算法

滑动窗口是对数据流进行连续查询处理、得出近似查询结果的一种常用的数据采样技术．连续查询处理的执行方式有2类：一类是立即执行方式；一类是周期执行方式、在已有的研究工作中，基于滑动窗口的连接算法都是适用于立即执行的连续查询．提出了适用于周期执行的连续查询的复合滑动窗口连接算法，即CSWSNLJ算法和CSWSNHJ算法．理论分析和试验结果表明CSWSNHJ算法具有较好的性能．     

An Indexed Non-Equijoin Algorithm Based on Sliding Windows over Data Streams

0 IntroductionJooipner partoorcess ,sihnags ,rebceeiinvged o nreen oefw tehdei nmtoersets tex dpueen stiovein qfiuneirteymemory requirements from stream-oriented applications .Symmetric HashJoin(SHJ)[1 ,2]which was originally designedto allowa high degree of pipeliningintraditional parallel data-base systems ,is an optional approach because both ofitsinputmust be kept in bounded memory during query execution.Butit leads into thrashing on larger inputs . To rectify the situa-tion,XJoinis pro…     

基于数据流频繁模式挖掘的入侵检测模型

计算机网络入侵通常具有高频度特性,因此,识别是否正常访问,对数据流中重复元素的挖掘,给出频度指标,是一种重要的依据.提出一种基于数据流频繁模式的改进型AFP算法,该算法采用滑动窗口树技术,单遍扫描数据流及时捕获网络上的最新模式信息,并将该算法应用在入侵检测模型中正常数据和异常数据的在线挖掘.解决了有限存储和无限数据流的矛盾.实验结果表明,该模型有较高的报警率和较低的误报率.     

支持复杂语义的数据流滑动窗口连接建模和查询优化

数据流连接操作的执行方式直接影响到查询执行的效率和结果的正确性.在STREAM项目流化方法的基础上,对复杂应用下的数据流滑动窗口连接的准确语义进行了分析和建模,以时间窗口连接的增量维护为例提出了两种改进的基本维护策略,给出了针对元组窗和分组窗的维护方法,讨论了根据参数和环境的不同进行适应性的维护.实验证明了在不同的窗口、流速和选择度下,适应性地选择不同的优化算法会达到最优的处理性能.     

滑动窗口下数据流完全加权最大频繁项集挖掘

针对当前关于数据流加权最大频繁项集WMFI(weighted maximal frequent itemsets)的研究无法有效地处理频繁阈值和加权频繁阈值不一致情况下WMFI的挖掘问题,提出了完全加权最大频繁项集FWM FI(full w eighted maximal frequent itemsets)的概念.为了减少naive算法在处理滑动窗口下完全加权最大频繁项集挖掘时存在的冗余运算,提出了FWMFI-SW(FWMFI mining based on sliding window over data stream)算法.所提出的算法通过基于频繁约束条件的优化策略减少了naive算法中M ax W优化策略的无效调用次数;采用编辑距离比率作为WMFP-SW-tree的重构判别函数,可以有效减少该树的重构次数.实验结果表明FWMFI-SW算法是有效的,且比naive算法更有时间优势.     

A hybrid model for the mid-long term runoff forecasting by evolutionary computation techniques

The mid-long term hydrology forecasting is one of most challenging problems in hydrological studies. This paper proposes an efficient dynamical system prediction model using evolutionary computation techniques. The new model overcomes some disadvantages of conventional hydrology forecasting ones. The observed data is divided into two parts: the slow “smooth and steady” data, and the fast “coarse and fluctuation” data. Under thedivide and conquer strategy, the behavior of smooth data is modeled by ordinary differential equations based on evolutionary modeling, and that of the coarse data is modeled using gray correlative forecasting method. Our model is verified on the test data of the mid-long term hydrology forecast in the northeast region of China. The experimental results show that the model is superior to gray system prediction model (GSPM). Foundation item: Supported by the National Natural Science Foundation of China ( 60133010, 70071042, 60073043) Biography: Zou Xiu-fen(1966-),female,Associate professor, research direction:evolutionary computing, parallel computing.     

A Fast Distributed Algorithm for Association Rule Mining Based on Binary Coding Mapping Relation

Association rule mining is an important issue in data mining. The paper proposed an binary system based method to generate candidate frequent itemsets and corresponding supporting counts efficiently, which needs only some operations such as ＂and＂, ＂or＂ and ＂xor＂. Applying this idea in the existed distributed association rule mining al gorithm FDM, the improved algorithm BFDM is proposed. The theoretical analysis and experiment testify that BFDM is effective and efficient.     

基于时间窗口权值的数据流分类算法

针对不同时间段的数据流对当前数据流分类影响程度不同,在滑动窗口技术基础上提出了时间窗口权值的频繁模式(TWWFP)分类算法.首先,对滑动窗口中的每个基本窗口赋予一个与时间有关的窗口权值;然后,采用TWWFP-Tree结构存储当前滑动窗口中每个基本窗口中的频繁数据属性,实时更新TWWFP-Tree结构;最后,检测相邻3个滑动窗口中权值属性的平均分类误差,发现突变后及时减少下一个滑动窗口的长度可适应数据流的变化.实验证明该分类算法比没有时间窗口权值分类算法的精确度最大提高3%.     

基于滑动窗口的动态数据流聚类算法研究

数据流聚类算法是当前数据流研究领域里的重要分支,而滑动窗口是数据流中一种关注近期数据的近似方法,提出一种采用滑动窗口处理数据的优化算法SWStream.算法采用双层架构思想,在线阶段利用滑动窗口树存储概要结构,动态调整窗口大小.而在离线阶段对上一阶段的结果进行宏聚类,得到最后的结果.实验验证本算法有更高的处理效率,也相对节约内存.     

Linked-Tree： An Aggregate Query Algorithm Based on Sliding Window over Data Stream

How to process aggregate queries over data streams efficiently and effectively have been becoming hot re search topics in both academic community and industrial community. Aiming at the issues, a novel Linked-tree algorithm based on sliding window is proposed in this paper. Due to the proposal of concept area, the Linked-tree algorithm reuses many primary results in last window and then avoids lots of unnecessary repeated comparison operations between two successive windows. As a result, execution efficiency of MAX query is improved dramatically. In addition, since the size of memory is relevant to the number of areas but irrelevant to the size of sliding window, memory is economized greatly. The extensive experimental results show that the performance of Linked-tree algorithm has significant improvement gains over the traditional SC （Simple Compared） algorithm and Ranked-tree algorithm.     

An Improved Genetic Algorithm for Problem of Genome Rearrangement

In view of the fact that the problem of sorting unsigned permutation by reversal is NP-hard, while the problem of sorting signed permutation by reversal can be solved easily, in this paper, we first transform an unsigned permutation of length n,π （π1 ,… ,πn）, into a set S（π） containing 2^n signed permutations, so that the reversal distance of π is equal to the reversal distance of the optimal signed permutation in S（π）. Then analyze the structural features of S（π） by creating a directed graph and induce a new computing model of this question. Finally, an improved genetic algorithm for solving the new model is proposed. Experimental results show that the proposed model and algorithm is very efficient in practice.     

一种基于混沌理论的数据流连续聚集查询预测算法

为了有效地预测聚集查询的未来聚集值,提出了一种基于混沌理论的数据流连续聚集查询预测未来聚集值算法——CSPA算法.数据流看作是以数据到达时间为序的一个时间序列,借鉴传统时间序列分析技术探讨了连续聚集查询的未来聚集值预测问题,但由于数据流序列与传统时间序列在时间间隔和数据集的处理上存在很大差别,于是采用流滑动窗口技术加以处理.其次,针对目前数据流聚集查询预测领域已有的一些研究结果都未考虑流数据内在的复杂非线性动力学特征对预测的影响问题,该算法又利用了混沌理论中的局域预测思想解决了这一不足.实验结果表明,利用该算法进行预测具有很好的准确性.     

Web Database Query Interface Annotation Based on User Collaboration

A vision based query interface annotation meth od is used to relate attributes and form elements in form based web query interfaces, this method can reach accuracy of 82%. And a user participation method is used to tune the result; user can answer ＂yes＂ or ＂no＂ for existing annotations, or manually annotate form elements. Mass feedback is added to the annotation algorithm to produce more accurate result. By this approach, query interface annotation can reach a perfect accuracy.     

An FPGA Implementation of GF （p） Elliptic Curve Cryptographic Coprocessor

A GF (p) elliptic curve cryptographic coprocessor is proposed and implemented on Field Programmable Gate Array (FPGA). The focus of the coprocessor is on the most critical, complicated and time-consuming point multiplications. The technique of coordinates conversion and fast multiplication algorithm of two large integers are utilized to avoid frequent inversions and to accelerate the field multiplications used in point multiplications. The characteristic of hardware parallelism is considered in the implementation of point multiplications. The coprocessor implemented on XILINX XC2V3000 computes a point multiplication for an arbitrarypoint on a curve defined over GF(2^192-2^64-1) with the frequency of 10 MHz in 4.40 ms in the average case and 5.74ms in the worst case. At the same circumstance, the coprocessor implemented on XILINX XC2V4000 takes 2.2 ms in the average case and 2.88 ms in the worst case.     

一种基于滑动窗口的一趟数据流聚类算法

在海量的动态数据流中发现有价值的知识,是数据挖掘技术研究的重要问题.研究数据流聚类,根据数据流的特点,提出了一种基于滑动窗口的一趟数据流挖掘的算法,对原有的一趟数据流聚类算法进行了改进,增强了一趟数据流聚类算法的扩展性,改进了数据流聚类的质量.     

一种基于可变滑动窗口的数据流分段聚类算法

数据流的应用越来越广泛,数据流挖掘成为数据挖掘的重点研究方向之一。在分析各种数据流聚类算法的基础上,提出了一种基于可变滑动窗口的数据流分段聚类算法。算法以时间序列数据流模式表示技术为参考,以去除噪音和压缩数据为目的,实现了数据流的特征提取和概要存储。实验表明,算法具有低时空复杂度、自适应等特点。     

抗阻塞干扰的低速率语音编码传输算法

为满足在跳频信道上的语音传输需求,研究了一种抗阻塞干扰的"滑动窗"语音传输算法。将传输码流均匀地分成若干片段,用定长的"滑动窗"在码流上滑动并截取其中的一段连续片段作为某跳频点的数据。接收端比较连续若干跳的重叠部分,判断并恢复出"坏跳"数据。对每个片段进行差错控制保护,通过"联合最大后验概率译码"的方法抵抗更高误码率的影响。测试表明:在有阻塞干扰的跳频信道上,"滑动窗"算法的分段信噪比平均高出传统的连续可变斜率增量调制算法20dB。     

Trustworthiness Technologies of DDSS

The most significant strategic development in information technology over the past years has been ＂trusted computing＂ and trusted computers have been produced. In this paper trusted mechanisms adopted by PC is imported into distributed system, such as chain of trust, trusted root and so on. Based on distributed database server system （DDSS）, a novel model of trusted distributed database server system （TDDSS） is presented ultimately. In TDDSS role-based access control, two-level of logs and other technologies are adopted to ensure the trustworthiness of the system.     

Theoretical investigation of negative refraction in metallic and ferromagnetic composites

A new design of LHM (left handed material) is suggested, in which the wave vector k and the energy flow S (the Poyming veclor) are in the opposite direction. Metallic cores or lines are coated with ferromagnetic layers to obtain negative permittivity and permeability. This design may bring some improvements over the binary design, such as higher homogeneity, smaller volume size, lower power loss, higher convenience and economy. The analytical expressions for the permiltivily s and permeability μ are shown to be negative in certain direction and frequency regions. Two specific structures are theoretically discussed and proved to be left-handed.     

Probabilistic Analysis on Connectivity for Sensor Grids with Unreliable Nodes

0 IntroductionWireless sensor networks consist of manynodes , each containing application-specificsensors ,a wirelesstransceiver ,anda si mple proces-sor[1-4]. Sensor networks have extensive applica-tions . A large number of research results can beseenin Refs .[5-7] .This paper mainly concerns with sensor net-works that are inherently unreliable. We consider anetwork with mn nodes ,arranged in a grid over asquare region of areaA. This model was presentedin[8 ,9].Each nodeis a sensor ,and can…