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不同的入侵检测系统,使用不同的数据属性。朴素贝叶斯(Naive Bayes简称NB)分类器由于其强独立性假设,并未考虑属性之间的相互关系,而入侵检测的数据集不能很好地满足条件假设,本文引入隐藏贝叶斯网络分类器,并将其应用于入侵检测中。该模型为每一个属性创建一个隐藏的父属性,它能影响到分类器的其它属性。实验表明,该算法可以优化朴素贝叶斯模型,能提高入侵检测系统的整体性能,效果更好。 相似文献
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基于因子分析的NBC及其在边坡识别中的应用 总被引:1,自引:0,他引:1
高岩 《计算机工程与设计》2011,32(11):3828-3831
满足条件独立性假设时,朴素贝叶斯分类器理论上比其它分类方法具有更高的分类正确率,但该假设在许多实际情况中并不成立,针对这一问题,提出了一种基于因子分析的朴素贝叶斯分类模型FA-NBC,并将其应用于边坡的稳定性识别。为了保证朴素贝叶斯分类器结构上的简单性,FA-NBC模型以方差贡献为依据构建新的属性集,新属性集包含原属性集的大部分信息且满足条件独立性假设。UCI数据集上的实验结果证明了FA-NBC模型的有效性。 相似文献
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高速网络环境中数据量日益增大,安全问题日益突出,对入侵检测技术提出了更高的要求.朴素贝叶斯作为数据挖掘的重要方法之一,在入侵检测中有着重要的地位.由于其属性独立假设,使得如何在海量高维数据处理背景下快速、准确、有效地选出代表原数据的属性显得尤为重要.本文提出了一种快速属性选择方法并结合朴素贝叶斯分类模型应用于入侵检测中.实验表明,结合了该属性选择方法的朴素贝叶斯分类器有很好的分类精度及较低的时空消耗. 相似文献
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基于有向树算法构造的TAN分类器 总被引:1,自引:0,他引:1
树扩展型朴素贝叶斯(TAN)分类器放松了朴素贝叶斯的属性独立性假设,是对朴素贝叶斯分类器的有效改进.但传统TAN的构造算法中树的根结点是随意选择的,这使得其无法精确表达属性间的依赖关系.通过将依赖关系设定方向,并将有向树算法引入TAN分类器的构造,提出了一种新的TAN模型构造方法--DTAN.实验结果表明,DTAN分类方法在实例个数比较多的数据集上具有显著优秀的分类性能. 相似文献
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一种限定性的双层贝叶斯分类模型 总被引:29,自引:1,他引:28
朴素贝叶斯分类模型是一种简单而有效的分类方法,但它的属性独立性假设使其无法表达属性变量间存在的依赖关系,影响了它的分类性能.通过分析贝叶斯分类模型的分类原则以及贝叶斯定理的变异形式,提出了一种基于贝叶斯定理的新的分类模型DLBAN(double-level Bayesian network augmented naive Bayes).该模型通过选择关键属性建立属性之间的依赖关系.将该分类方法与朴素贝叶斯分类器和TAN(tree augmented naive Bayes)分类器进行实验比较.实验结果表明,在大多数数据集上,DLBAN分类方法具有较高的分类正确率. 相似文献
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朴素贝叶斯分类器是一种简单而高效的分类器,但需要属性独立性假设,无法表示现实世界中属性之间的依赖关系,影响了其分类性能.利用独立分量分析提升朴素贝叶斯分类性能,把样本投影到由独立分量所确定的特征空间,提高了朴素贝叶斯分类器的分类性能.实验结果表明,这种基于独立分量分析的朴素贝叶斯分类器具有良好的性能. 相似文献
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朴素贝叶斯分类器是一种简单而高效的分类器,但是其属性独立性假设限制了对实际数据的应用。提出一种新的算法,该算法为避免数据预处理时,训练集的噪声及数据规模使属性约简的效果不太理想,并进而影响分类效果,在训练集上通过随机属性选取生成若干属性子集,并以这些子集构建相应的贝叶斯分类器,进而采用遗传算法进行优选。实验表明,与传统的朴素贝叶斯方法相比,该方法具有更好的分类精度。 相似文献
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基于遗传算法的朴素贝叶斯分类 总被引:1,自引:0,他引:1
朴素贝叶斯分类器是一种简单而高效的分类器,但是其属性独立性假设限制了对实际数据的应用。提出一种新的算法,该算法为避免数据预处理时,训练集的噪声及数据规模使属性约简的效果不太理想,并进而影响分类效果,在训练集上通过随机属性选取生成若干属性子集,并以这些子集构建相应的贝叶斯分类器,进而采用遗传算法进行优选。实验表明,与传统的朴素贝叶斯方法相比,该方法具有更好的分类精度。 相似文献
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A certain assumption that appears in the proof of correctness of the standard Boltzmann machine learning procedure is investigated. The assumption, called the clamping assumption, concerns the behavior of a Boltzmann machine when some of its units are clamped to a fixed state. It is argued that the clamping assumption is essentially an assertion of the time reversibility of a certain Markov chain underlying the behavior of the Boltzmann machine. As such, the clamping assumption is generally false, though it is certainly true of the Boltzmann machines themselves. The author also considers how the concept of the Boltzmann machine may be generalized while retaining the validity of the clamping assumption. 相似文献
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Comments on "a separable low complexity 2D HMM with application to face recognition' 总被引:1,自引:0,他引:1
The separable low complexity 2D HMM proposed in the paper by Othman and Aboulnasr (2003) builds on the assumption of conditional independence in the relationship between adjacent blocks. The authors view this assumption as the key assumption to reduce the complexity. In this communication, we show that this key assumption is entirely unnecessary 相似文献
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由于作为朴素贝叶斯分类器的主要特征的条件独立性假设条件过强且在不同数据集上表现出的差异,所以独立性假设成为众多改进算法的切入点。但也有研究指出不满足该假设并没有对分类器造成预想的影响。从降低后验概率的估计误差入手提出一种条件熵匹配的半朴素贝叶斯分类器。实验证明,该方法能有效提高朴素贝叶斯分类器的性能。 相似文献
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Sanjoy Baruah 《Real-Time Systems》2014,50(3):317-341
Model-based design methodologies based on the synchrony assumption are widely used in many safety-critical application domains. The synchrony assumption asserts that actions (such as the execution of code) occur instantaneously; however, physical platforms obviously do not possess this property. This paper considers the problem of obtaining resource-efficient implementations of programs that are written under the synchrony assumption on actual platforms, such that these implementations execute in a manner that is semantically consistent with the execution sequences that would occur if the synchrony assumption were to hold. 相似文献
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In this note, we discuss the problem of the sample-path-based (on-line) performance gradient estimation for Markov systems.
The existing on-line performance gradient estimation algorithms generally require a standard importance sampling assumption.
When the assumption does not hold, these algorithms may lead to poor estimates for the gradients. We show that this assumption
can be relaxed and propose algorithms with multi-step sampling for performance gradient estimates; these algorithms do not
require the standard assumption. Simulation examples are given to illustrate the accuracy of the estimates. 相似文献
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The traditional statistical assumption for interpreting histograms and justifying approximate query processing methods based on them is that all elements in a bucket have the same frequency—this is called uniform distribution assumption. In this paper, we analyze histograms from a statistical point of view. We show that a significantly less restrictive statistical assumption – the elements within a bucket are randomly arranged even though they might have different frequencies – leads to identical formulas for approximating aggregate queries using histograms. Under this assumption, we analyze the behavior of both unidimensional and multidimensional histograms and provide tight error guarantees for the quality of approximations. We conclude that histograms are the best estimators if the assumption holds; sampling and sketching are significantly worse. As an example of how the statistical theory of histograms can be extended, we show how XSketches – an approximation technique for XML queries that uses histograms as building blocks – can be statistically analyzed. The combination of the random shuffling assumption and the other statistical assumptions associated with XSketch estimators ensures a complete statistical model and error analysis for XSketches. 相似文献
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Stephen L. Campbell 《Automatica》1981,17(4):645-646
In a recent paper by B. A. Francis, an assumption was made that guaranteed convergence in the boundary layer for singularly perturbed linear systems, but the assumption was not discussed. This note examines this assumption in some detail. Verifiable sufficient and necessary conditions are given. Illustrative examples are presented. 相似文献
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数字指纹编码与嵌入假设 总被引:1,自引:0,他引:1
数字指纹系统是数字水印技术的一个重要分支,是用于盗版追踪的一种技术。离散指纹编码和连续指纹编码是数字指纹研究领域的两大阵营。本文介绍了嵌入假设对指纹编码研究的重要意义,指出这两种研究方向的主要分歧在于对待嵌入假设条件的态度不同。从嵌入假设条件出发分析了离散指纹编码和连续指纹编码的基本思路、面临的挑战和发展趋势。 相似文献