电子政务中时态信息的研究

随着计算机技术和网络技术的发展，电子政务在我国开始全面实施。但是其中存在着诸如对信息时效性不能很好地处理等问题，这使其推广受到阻碍。通过分析目前电子政务中信息处理方法的不足，结合时态数据库的理论和方法，提出了一个解决电子政务中信息有效性的处理模型。     

基于恒等子图搜索的点模式匹配算法

点模式匹配问题是计算机视觉和模式识别领域中的一个重要课题,但由于噪声、视场等因素始终难以完全解决.通过构建点模式关系图,把点模式匹配问题转化为关系图最大恒等子图搜索问题,由此给出图、子图、图同构和恒等、支持顶点对及支持顶点对集的概念并对它们满足的一些性质和定理进行了证明,最后提出了一种对最大恒等子图搜索的有效算法,在对...     

基于时态关系代数的工作流引擎

对于工作流系统中普遍存在的时态信息,由于后台关系数据库管理系统难以很好处理,造成工作流引擎需要进行相关的时态信息处理。提出在时态数据库平台上建立工作流管理系统的架构,并采用时态关系代数描述工作流引擎运行中涉及的时态信息,证明了该架构的优势。最后以一个例子分析该架构下的工作流执行过程。     

基于特征值的多模式匹配算法

高速网是当今网络发展的必然趋势,采用现行匹配算法的入侵检测系统(IDS)很难在高速网中有效地运行。本文主要从特征值的多模式匹配算法、模式库的组织和逻辑实现这三个方面来大幅度地提高系统检测速率,完全适应于高速网络的入侵检测。     

高效的模式匹配算法研究

对入侵检测中模式匹配的方法进行了研究,分析了当前常用的模式匹配方法的弱点与不足,提出了一种基于三叉树结构的自动机方法,较好的避免了传统树型结构中由于节点数目变化而导致的不便。此外,利用匹配失败的信息,实现了跳跃匹配,提高了模式匹配的速度。*     

基于遗传算法图像模式匹配的收敛性研究

介绍了采用遗传算法进行图像模式匹配的程序概要设计,通过实例分析说明了影响GA收敛性的5个因素。通过研究GA收敛性揭示了图像匹配GA搜索过程的一些规律,为遗传选择策略特别是遗传算子的设计提供了参考。     

频繁子图挖掘研究综述

归纳了频繁子图挖掘方法的处理流程,分析评价了频繁子图挖掘的典型算法:广度优先搜索和深度优先搜索的频繁子图挖掘算法,概述了频繁子图挖掘研究的平台--图模型及其产生器,并对频繁子图挖掘方法未来研究方向进行了展望.     

基于GMM模型的声纹识别模式匹配研究

模式匹配是声纹识别的关键问题之一,为了提高识别正确率和识别效率,本文采用GMM模型建模,训练阶段利用EM算法求取参数集,并通过MAP准则实现模式识别。引入LBG算法求取起始参数值,并设计了基于3种方法的联合判决门限决策。实验结果表明 GMM模型利用平均值向量和协方差矩阵使它具有更好的模型能力,当高斯混合数为32时识别率达到最高,联合判决门限决策有效降低了误识率与虚警率,并提高了识别效率。     

字符串模式匹配算法的研究及改进

串的模式匹配是一种重要的串运算。本文首先对朴素的模式匹配BF算法与KMP算法进行了分析,在此基础上寻求出一种简单实用、易于理解的字符串模式匹配改进算法。结果表明改进算法能减少模式匹配中字符的比较次数和尝试次数,提高模式匹配的效率。     

A universal predictor based on pattern matching

We consider a universal predictor based on pattern matching. Given a sequence X₁, ..., X_n drawn from a stationary mixing source, it predicts the next symbol X_n+1 based on selecting a context of X_n+1. The predictor, called the sampled pattern matching (SPM), is a modification of the Ehrenfeucht-Mycielski (1992) pseudorandom generator algorithm. It predicts the value of the most frequent symbol appearing at the so-called sampled positions. These positions follow the occurrences of a fraction of the longest suffix of the original sequence that has another copy inside X₁X₂···X_n ; that is, in SPM, the context selection consists of taking certain fraction of the longest match. The study of the longest match for lossless data compression was initiated by Wyner and Ziv in their 1989 seminal paper. Here, we estimate the redundancy of the SPM universal predictor, that is, we prove that the probability the SPM predictor makes worse decisions than the optimal predictor is O(n^-ν) for some 0<ν<½ as n→∞. As a matter of fact, we show that we can predict K=O(1) symbols with the same probability of error     

一种基于模板匹配的语音识别算法

语音识别是语音信号处理的一个重要研究方向,涉及到生理学、心理学、语言学、计算机科学以及信号处理等诸多领域,广泛应用于控制、通信、消费品等行业。文中介绍了一种简单的语音识别算法。该算法主要流程包括预处理、端点检测、提取特征值、模式匹配4个过程,其中端点检测以幅值为标准,特征值采用临界带特征矢量,模板匹配采用DTW算法。主...     

一种基于时序特征匹配的信号配对方法

针对协同问答模式下无线电信号配对关系分析的需求,提出了一种基于信号时间序列匹配的询问应答信号配对方法。该方法提取侦察传感器获取的信号模式、到达时间、节点位置等参数,反向推算信号发射时间序列,通过时序匹配算法对询问和应答信号进行准确配对,从而提取节点间问答关系。计算机仿真验证了方法的有效性,在一定的条件下配对正确率超过95%。     

A recursive MISD architecture for pattern matching

Many applications require searching for multiple patterns in large data streams for which there is no preprocessed index to rely on for efficient lookups. An multiple instruction stream-single data stream (MISD) VLSI architecture that is based on a recursive divide and conquer approach to pattern matching is proposed. This architecture allows searching for multiple patterns simultaneously. The patterns can be constructed much like regular expressions, and add features such as requiring subpatterns to match in a specific order with some fuzzy distance between them, and the ability to allow errors according to prescribed thresholds, or ranges of such. The current implementation permits up to 127 simultaneous patterns at a clock frequency of 100 MHz, and does 1.024/spl times/10/sup 11/ character comparisons per second.     

Blind pattern matching attack on watermarking systems

Billions of dollars allegedly lost to piracy of multimedia content have triggered the industry to rethink the way music and films are distributed on the Internet. As encryption is vulnerable to digital or analog re-recording, currently almost all copyright protection mechanisms rely to a certain extent on watermarking. A watermark is an imperceptive secret hidden into a host signal. We analyze the security of multimedia copyright protection systems that use watermarks by proposing a new breed of attacks on generic watermarking systems. A typical blind pattern matching attack relies on the observation that multimedia content is often highly repetitive. Thus, the attack procedure identifies subsets of signal blocks that are similar and permutes these blocks. Assuming the permuted blocks are marked with distinct secrets, it can be shown that any watermark detector is facing a task of exponential complexity to reverse the permutations as a preprocessing step for watermark detection. We describe the logistics of the attack and an implementation against a spread-spectrum and a quantization index modulation data hiding technology for audio signals.     

Bit-sequential array for pattern matching

This letter presents the design and analysis of a bit-sequential array for pattern matching applications. The architecture makes multiple use of each data sample, has built-in concurrency and pipelining, and is based on a highly modular design with only nearest neighbor connections between array modules. The array computes all occurrences of a pattern of length m, in the string of length n, in O(m + n) time and O(m) hardware. The pattern and the string are fed in sequentially and the match indicators come out in the same fashion, leading to a significant reduction in silicon area.     

DEDUCE: A pattern matching method for automatic de-identification of Dutch medical text

In order to use medical text for research purposes, it is necessary to de-identify the text for legal and privacy reasons. We report on a pattern matching method to automatically de-identify medical text written in Dutch, which requires a low amount of effort to be hand tailored. First, a selection of Protected Health Information (PHI) categories is determined in cooperation with medical staff. Then, we devise a method for de-identifying all information in one of these PHI categories, that relies on lookup tables, decision rules and fuzzy string matching. Our de-identification method DEDUCE is validated on a test corpus of 200 nursing notes and 200 treatment plans obtained from the University Medical Center Utrecht (UMCU) in the Netherlands, achieving a total micro-averaged precision of 0.814, a recall of 0.916 and a F₁-score of 0.862. For person names, a recall of 0.964 was achieved, while no names of patients were missed.     

Interactive pattern analysis and classification systems: A survey and commentary

Starting with the era of learning machines, reasons are presented for the current emergence of graphics-oriented interactive pattern analysis and classification systems (IPACS) as a general approach to practical pattern-recognition problems. A number of representative systems and their application to a wide variety of patterns are surveyed. Various aspects of alternative hardware and software implementations are commented upon and computational algorithms and mappings relevant to interactive analysis and classification of patterns are discussed.     

基于多尺度时域矩匹配的自适应非均匀性校正算法

非制冷红外焦平面阵列的固定图案噪声具有与条带噪声相类似的特性.通过对矩匹配算法和时域高通滤波算法的研究, 提出了一种多尺度时域矩匹配非均匀性校正算法.首先利用高斯金字塔对相邻帧待校正图像进行全局运动估计, 然后对各尺度的高斯金字塔和拉普拉斯金字塔分别进行时域矩匹配.对真实红外图像序列的实验结果表明, 该算法在提高收敛速度的同时可有效减少鬼影现象的出现.     

NIDS中协议分析和模式匹配的研究

对入侵检测系统中的关键部分一检测引擎的数据分析中的模式匹配技术和协议分析技术进行了介绍。讨论了模式匹配中最常用的两种算法一KMP算法和BM算法，重点分析了模式匹配技术运用在网络级入侵检测系统中的不足，并指出结合使用协议分析和模式匹配进行数据分析的优越性。