基于免疫遗传算法的支持向量机参数优化及其应用

支持向量机是在统计学习理论基础上发展起来的一种性能优良的新型机器学习方法,它具有坚实的理论基础,巧妙的算法实现。支持向量机的卓越性能依赖于它的参数的正确选择。本文采用改进的免疫遗传算法对支持向量机的参数进行优化。实验证明对于低维数据分类时,本文的优化算法比传统的网格法可以较大减少参数优化时间和提升分类的准确率。对高维的文本数据分类时,在保证分类准确率的前提下,仍然可以较大减少优化的时间。     

基于对偶随机投影的线性核支持向量机

针对大型支持向量机（SVM）经随机投影特征降维后分类精度下降的问题,结合对偶恢复理论,提出了面向大规模分类问题的基于对偶随机投影的线性核支持向量机（drp-LSVM）。首先,分析论证了drp-LSVM相关几何性质,证明了在保持与基于随机投影降维的支持向量机（rp-LSVM）相近几何优势的同时,其划分超平面更接近于用全部数据训练得到的原始分类器。然后,针对提出的drp-LSVM快速求解问题,改进了传统的序列最小优化（SMO）算法,设计了基于改进SMO算法的drp-LSVM分类器。最后实验结果表明,drp-LSVM在继承rp-LSVM优点的同时,减小了分类误差,提高了训练精度,并且各项性能评价更接近于用原始数据训练得到的分类器;设计的基于改进SMO算法的分类器不但可以减少内存消耗,同时可以拥有较高的训练精度。     

An enhanced Support Vector Machine classification framework by using Euclidean distance function for text document categorization

This paper presents the implementation of a new text document classification framework that uses the Support Vector Machine (SVM) approach in the training phase and the Euclidean distance function in the classification phase, coined as Euclidean-SVM. The SVM constructs a classifier by generating a decision surface, namely the optimal separating hyper-plane, to partition different categories of data points in the vector space. The concept of the optimal separating hyper-plane can be generalized for the non-linearly separable cases by introducing kernel functions to map the data points from the input space into a high dimensional feature space so that they could be separated by a linear hyper-plane. This characteristic causes the implementation of different kernel functions to have a high impact on the classification accuracy of the SVM. Other than the kernel functions, the value of soft margin parameter, C is another critical component in determining the performance of the SVM classifier. Hence, one of the critical problems of the conventional SVM classification framework is the necessity of determining the appropriate kernel function and the appropriate value of parameter C for different datasets of varying characteristics, in order to guarantee high accuracy of the classifier. In this paper, we introduce a distance measurement technique, using the Euclidean distance function to replace the optimal separating hyper-plane as the classification decision making function in the SVM. In our approach, the support vectors for each category are identified from the training data points during training phase using the SVM. In the classification phase, when a new data point is mapped into the original vector space, the average distances between the new data point and the support vectors from different categories are measured using the Euclidean distance function. The classification decision is made based on the category of support vectors which has the lowest average distance with the new data point, and this makes the classification decision irrespective of the efficacy of hyper-plane formed by applying the particular kernel function and soft margin parameter. We tested our proposed framework using several text datasets. The experimental results show that this approach makes the accuracy of the Euclidean-SVM text classifier to have a low impact on the implementation of kernel functions and soft margin parameter C.     

Chaotic antlion algorithm for parameter optimization of support vector machine

Support Vector Machine (SVM) is one of the well-known classifiers. SVM parameters such as kernel parameters and penalty parameter (C) significantly influence the classification accuracy. In this paper, a novel Chaotic Antlion Optimization (CALO) algorithm has been proposed to optimize the parameters of SVM classifier, so that the classification error can be reduced. To evaluate the proposed algorithm (CALO-SVM), the experiment adopted six standard datasets which are obtained from UCI machine learning data repository. For verification, the results of the CALO-SVM algorithm are compared with grid search, which is a conventional method of searching parameter values, standard Ant Lion Optimization (ALO) SVM, and three well-known optimization algorithms: Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Social Emotional Optimization Algorithm (SEOA). The experimental results proved that the proposed algorithm is capable of finding the optimal values of the SVM parameters and avoids the local optima problem. The results also demonstrated lower classification error rates compared with GA, PSO, and SEOA algorithms.     

基于支持向量机的枪弹外观缺陷识别与分类

为解决枪弹外观缺陷自动分类问题,提出了一种基于支持向量机的枪弹外观缺陷自动识别与分类模型。首先针对枪弹表面缺陷的图像特点,从几何、灰度、纹理三方面进行了特征提取,在此基础上建立了基于支持向量机的枪弹外观缺陷分类模型,并对特征参数进行了优选;研究了支持向量机中惩罚系数和核函数参数对分类器性能的影响;通过实验与基于BP神经网络的枪弹外观缺陷分类器进行了比较,结果表明,在小样本下,基于支持向量机的枪弹外观缺陷分类器性能更好。     

Associated evolution of a support vector machine-based classifier for pedestrian detection

Support vector machine (SVM) has become a dominant classification technique used in pedestrian detection systems. In such systems, classifiers are used to detect pedestrians in some input frames. The performance of a SVM classifier is mainly influenced by two factors: the selected features and the parameters of the kernel function. These two factors are highly related and therefore, it is desirable that the two factors can be analyzed simultaneously, which are usually not the case in the previous work.In this paper, we propose an evolutionary method to simultaneously optimize the feature set and the parameters for the SVM classifier. Specifically, adaptive genetic operators were designed to be suitable for the feature selection and parameter tuning. The proposed method is used to train a SVM classifier for pedestrian detection. Experiments in real city traffic scenes show that the proposed approach leads to higher detection accuracy and shorter detection time.     

Design of semi-tensor product-based kernel function for SVM nonlinear classification

The kernel function method in support vector machine (SVM) is an excellent tool for nonlinear classification. How to design a kernel function is difficult for an SVM nonlinear classification problem, even for the polynomial kernel function. In this paper, we propose a new kind of polynomial kernel functions, called semi-tensor product kernel (STP-kernel), for an SVM nonlinear classification problem by semi-tensor product of matrix (STP) theory. We have shown the existence of the STP-kernel function and verified that it is just a polynomial kernel. In addition, we have shown the existence of the reproducing kernel Hilbert space (RKHS) associated with the STP-kernel function. Compared to the existing methods, it is much easier to construct the nonlinear feature mapping for an SVM nonlinear classification problem via an STP operator.     

基于SVM的语音关键词确认方法研究

对支持向量机理论进行了简要分析,并将支持向量机引入汉语语音关键词识别系统中,根据关键词置信度将关键词假想命中分为接受和拒识两类,从而提高系统正确识别率。针对线性支持向量机、不同核函数下的非线性支持向量机以及核函数为径向基函数时支持向量机的性能做了一些相关实验。实验结果显示,支持向量机是一种相当有效的关键词确认方法。     

Learning Semi-Structured Document Categorization Using Bounded-Length Spectrum Sub-Sequence Kernels

In this paper we report an investigation into the learning of semi-structured document categorization. We automatically discover low-level, short-range byte data structure patterns from a document data stream by extracting all byte sub-sequences within a sliding window to form an augmented (or bounded-length) string spectrum feature map and using a modified suffix trie data structure (called the coloured generalized suffix tree or CGST) to efficiently store and manipulate the feature map. Using the CGST we are able to efficiently compute the stream's bounded-length sequence spectrum kernel. We compare the performance of two classifier algorithms to categorize the data streams, namely, the SVM and Naive Bayes (NB) classifiers. Experiments have provided good classification performance results on a variety of document byte streams, particularly when using the NB classifier under certain parameter settings. Results indicate that the bounded-length kernel is superior to the standard fixed-length kernel for semi-structured documents.     

支持向量机分类器遥感图像分类研究

SVM分类器核函数的选择以及参数的设置直接影响系统的泛化能力和运行速度。引入交叉验证技术和栅格搜索技术,对径向基核、多项式核和Sigmoid核函数应用于图像多类别分类的性能进行理论推导、测试及分析,求得三种核函数应用于SVM分类器的性能,并证明了栅格搜索寻找最优参数的有效性。最后通过对TM 6波段BSQ格式遥感图像进行分类对比证明了SVM分类器核函数用于TM图像分类的可行性及高效性。     

基于KNN和RVM的分类方法——KNN RVM分类器

针对相关向量机(RVM)算法分类精度低、核参数选择困难等问题,文中提出临界滑动阈值的概念并以其为基础将RVM与K近邻(KNN)算法结合构建分类器——KNN-RVM分类器。从理论上提出并证明KNN-RVM分类过程等价于带软间隔约束的支持向量机的分类过程、KNN-RVM分类器等价于每类只选一个代表点的1-NN分类器、KNN-RVM分类效果优于RVM这3个结论。对这3个不同数据集进行实验证明临界滑动阈值的临界性与滑动性及KNN-RVM分类器的准确性、适应性及全局最优性,提高分类精度,减轻算法对核参数的依赖性,进而证明KNN-RVM分类器是一种有效的分类器。     

基于遗传算法优化SVM的嵌入式网络系统异常入侵检测

由于传统嵌入式网络系统入侵检测方法难以获得较高的检测精度,提出基于遗传算法优化的支持向量机(GA-SVM)的网络入侵检测技术.支持向量机分类器能够较好地解决少样本、高维、非线性分类问题.然而,支持向量机训练参数的选择对其分类精度有着很大影响,遗传算法能够同时优化支持向量机的训练参数,采用遗传算法进行支持向量机的训练参数同步优化.实验结果表明,这种遗传算法优化的支持向量机分类入侵检测模型有着很高的检测精度.     

Imbalanced data classification based on scaling kernel-based support vector machine

In many classification problems, the class distribution is imbalanced. Learning from the imbalance data is a remarkable challenge in the knowledge discovery and data mining field. In this paper, we propose a scaling kernel-based support vector machine (SVM) approach to deal with the multi-class imbalanced data classification problem. We first use standard SVM algorithm to gain an approximate hyperplane. Then, we present a scaling kernel function and calculate its parameters using the chi-square test and weighting factors. Experimental results on KEEL data sets show the proposed algorithm can resolve the classifier performance degradation problem due to data skewed distribution and has a good generalization.     

基于SVM的房贷信用评估的应用研究

信贷风险是金融机构风险主要来源.支持向量机(SVM)在解决两类问题上是一种较好的分类方法,其学习模型有较强的稳定性.对SVM在房贷信用评估应用中的问题进行了研究和解决,如核函数选取,参数选取,样本非均衡问题等.实验得出在实际应用中径向基模型较好,采用Grid-search方法调整参数,能达到更好的推广能力和预测结果,用分别惩罚支持向量机能有效解决样本非均衡问题.试验结果也证明了基于SVM的房贷信用评估方法优于原有的打分方法.     

Motor Imagery Electroencephalograph Classification Based on Optimized Support Vector Machine by Magnetic Bacteria Optimization Algorithm

In this paper, an optimized support vector machine (SVM) based on a new bio-inspired method called magnetic bacteria optimization algorithm method is proposed to construct a high performance classifier for motor imagery electroencephalograph based brain–computer interface (BCI). Butterworth band-pass filter and artifact removal technique are combined to extract the feature of frequency band of the ERD/ERS. Common spatial pattern is used to extract the feature vector which are put into the classifier later. The optimization mechanism involves kernel parameters setting in the SVM training procedure, which significantly influences the classification accuracy. Our novel approach aims to optimize the penalty factor parameter C and kernel parameter g of the SVM. The experimental results on the BCI Competition IV dataset II-a clearly present the effectiveness of the proposed method outperforming other competing methods in the literature such as genetic algorithm, particle swarm algorithm, artificial bee colony, biogeography based optimization.     

Kernel selection in multi-class support vector machines and its consequence to the number of ties in majority voting method

Support vector machines are a relatively new classification method which has nowadays established a firm foothold in the area of machine learning. It has been applied to numerous targets of applications. Automated taxa identification of benthic macroinvertebrates has got generally very little attention and especially using a support vector machine in it. In this paper we investigate how the changing of a kernel function in an SVM classifier effects classification results. A novel question is how the changing of a kernel function effects the number of ties in a majority voting method when we are dealing with a multi-class case. We repeated the classification tests with two different feature sets. Using SVM, we present accurate classification results proposing that SVM suits well to the automated taxa identification of benthic macroinvertebrates. We also present that the selection of a kernel has a great effect on the number of ties.     

ECG beat classification using particle swarm optimization and support vector machine

In this paper, we propose a novel ECG arrhythmia classification method using power spectral-based features and support vector machine (SVM) classifier. The method extracts electrocardiogram’s spectral and three timing interval features. Non-parametric power spectral density (PSD) estimation methods are used to extract spectral features. The proposed approach optimizes the relevant parameters of SVM classifier through an intelligent algorithm using particle swarm optimization (PSO). These parameters are: Gaussian radial basis function (GRBF) kernel parameter σ and C penalty parameter of SVM classifier. ECG records from the MIT-BIH arrhythmia database are selected as test data. It is observed that the proposed power spectral-based hybrid particle swarm optimization-support vector machine (SVMPSO) classification method offers significantly improved performance over the SVM which has constant and manually extracted parameter.     

Methods for the combination of kernel matrices within a support vector framework

The problem of combining different sources of information arises in several situations, for instance, the classification of data with asymmetric similarity matrices or the construction of an optimal classifier from a collection of kernels. Often, each source of information can be expressed as a similarity matrix. In this paper we propose a new class of methods in order to produce, for classification purposes, a single kernel matrix from a collection of kernel (similarity) matrices. Then, the constructed kernel matrix is used to train a Support Vector Machine (SVM). The key ideas within the kernel construction are twofold: the quantification, relative to the classification labels, of the difference of information among the similarities; and the extension of the concept of linear combination of similarity matrices to the concept of functional combination of similarity matrices. The proposed methods have been successfully evaluated and compared with other powerful classifiers and kernel combination techniques on a variety of artificial and real classification problems.     

一种基于样本加权的多尺度核支持向量机方法

多核学习方法是机器学习领域中的一个新的热点。核方法通过将数据映射到高维空间来增加线性分类器的计算能力,是目前解决非线性模式分析与分类问题的一种有效途径。但是在一些复杂的情况下,单个核函数构成的核学习方法并不能完全满足如数据异构或者不规则、样本规模大、样本分布不平坦等实际应用中的需求问题,因此将多个核函数进行组合以期获得更好的结果,是一种必然的发展趋势。因此提出一种基于样本加权的多尺度核支持向量机方法,通过不同尺度核函数对样本的拟合能力进行加权,从而得到基于样本加权的多尺度核支持向量机决策函数。通过在多个数据集上的实验分析可以得出所提方法对于各个数据集都获得了很高的分类准确率。     

Quadratic-radial-basis-function-kernel for classifying multi-class agricultural datasets with continuous attributes

Classification of agricultural data such as soil data and crop data is significant as it allows the stakeholders to make meaningful decisions for farming. Soil classification aids farmers in deciding the type of crop to be sown for a particular type of soil. Similarly, wheat variety classification assists in selecting the right type of wheat for a particular product. Current methods used for classifying agricultural data are mostly manual. These methods involve agriculture field visits and surveys and are labor-intensive, expensive, and prone to human error. Recently, data mining techniques such as decision trees, k-nearest neighbors (k-NN), support vector machine (SVM), and Naive Bayes (NB) have been used in classification of agricultural data such as soil, crops, and land cover. The resulting classification aid the decision making process of government organizations and agro-industries in the field of agriculture. SVM is a popular approach for data classification. A recent study on SVM highlighted the fact that using multiple kernels instead of a single kernel would lead to better performance because of the greater learning and generalization power. In this work, a hybrid kernel based support vector machine (H-SVM) is proposed for classifying multi-class agricultural datasets having continuous attributes. Genetic algorithm (GA) or gradient descent (GD) methods are utilized to select the SVM parameters C and γ. The proposed kernel is called the quadratic-radial-basis-function kernel (QRK) and it combines both quadratic and radial basis function (RBF) kernels. The proposed classifier has the ability to classify all kinds of multi-class agricultural datasets with continuous features. Rigorous experiments using the proposed method are performed on standard benchmark and real world agriculture datasets. The results reveal a significant performance improvement over state of the art methods such as NB, k-NN, and SVM in terms of performance metrics such as accuracy, sensitivity, specificity, precision, and F-score.