基于最小二乘支持向量机的非平衡分布数据分类

支持向量机是在统计学习理论基础上发展起来的一种十分有效的分类方法。然而当两类样本数量相差悬殊时,会引起支持向量机分类能力的下降。为了提高支持向量机的非平衡数据分类能力,文章分析了最小二乘支持向量机的本质特征,提出了一种非平衡数据分类算法。在UCI标准数据集上进行的实验表明,该算法能够有效提高支持向量机对非均衡分布数据的正确性,尤其对于大规模训练集的情况,该算法在保证不损失训练精度的前提下,使训练速度有较大提高。     

基于自适应步长的支持向量机快速训练算法*

支持向量机训练问题实质上是求解一个凸二次规划问题。当训练样本数量非常多时, 常规训练算法便失去了学习能力。为了解决该问题并提高支持向量机训练速度,分析了支持向量机的本质特征,提出了一种基于自适应步长的支持向量机快速训练算法。在保证不损失训练精度的前提下,使训练速度有较大提高。在UCI标准数据集上进行的实验表明,该算法具有较好的性能,在一定程度上克服了常规支持向量机训练速度较慢的缺点、尤其在大规模训练集的情况下,采用该算法能够较大幅度地减小计算复杂度,提高训练速度。     

一种支持向量机的快速分类算法

鉴于传统支持向量机分类过程的计算量和支持向量的个数成正比,为了提高分类决策的速度,提出一种约简支持向量的快速分类算法,该算法对原始的支持向量进行特定比例的模糊均值聚类操作,按照分类误差最小的原则构建最小线性二乘回归模型,求解新的支持向量系数和决策函数的偏置.人造数据集和标准数据集上的实验表明,约简50%支持向量后,可以在保持分类精度在无统计意义的明显损失的前提下,使得分类速度提高50%.     

一种快速的支持向量机多类分类算法

提出了一种快速的支持向量机多类分类算法.首先用每类训练样本的样本数作为权值构造最优二叉树,然后对每个非叶子结点训练两类分类器.分类时,从二叉树根结点开始逐层向下分类,直到某一叶子结点,该结点对应的类别即为待分类样本的类别.在Reuters 21578标准数据集上进行的分类实验表明,该算法具有较好的性能,在一定程度上克服了现有的支持向量机多类分类算法分类速度较慢的缺点,尤其在类别数较多、各类样本规模相同的情况下,采用该算法能够较大幅度地提高分类速度.     

基于OC-SVM的大型数据集分类方法

支持向量机是最有效的分类技术之一,具有很高的分类精度和良好的泛化能力,但其应用于大型数据集时的训练过程还是非常复杂。对此提出了一种基于单类支持向量机的分类方法。采用随机选择算法来约简训练集,以达到提高训练速度的目的;同时,通过恢复超球体交集中样本在原始数据中的邻域来保证支持向量机的分类精度。实验证明,该方法能在较大程度上减小计算复杂度,从而提高大型数据集中的训练速度。     

多项式核函数SVM快速分类算法

标准的SVM分类计算过程中有大量的支持向量参与了计算，导致了分类速度缓慢。该文为提高SVM的分类速度，提出了一种快速的多项式核函数SVM分类算法，即将使用多项式核的SVM分类决策函数展开为关于待分类向量各分量的多项式，分类时通过计算各个多项式的值而得到分类结果，使分类计算量和支持向量数量无关，又保留了全部支持向量的信息。当多项式核函数的阶数或待分类向量的维数较低而支持向量数量较多时，使用该算法可以使SVM 分类的速度得到极大的提高。针对实际数据集的实验表明了该算法的有效性。     

基于人工鱼群优化的直推式支持向量机分类算法

提出基于人工鱼群优化的直推式支持向量机分类算法。该算法使直推式学习思想的优势得到充分的展现,在部分UCI标准数据集和20-Newgroups文本实验数据集上的对比实验表明,该算法较经典支持向量机算法和基于蚁群算法的直推式支持向量机算法具有更高的分类性能。     

面向不平衡样本集的变速器故障分类判别算法研究

针对变速器新产品故障检测问题,提出以阶次分析进行故障特征提取和支持向量机分类器进行故障分类的方法.通过建立二层支持向量机分类判别模型和对惩罚因子C的调整,解决了在训练样本集不平衡的情况下标准支持向量机分类器的分类面偏向样本数量较多类别的问题.通过对现场数据的实验结果表明,该方法的故障识别率和运行时间比BP神经网络和标准支持向量机算法均有较大提高.     

改进的最小二乘支持向量机在入侵检测系统中的应用

介绍最小二乘支持向量机的基本原理论．提出基于最小二乘支持向量机的网络入侵检测系统模型。由于计算经验风险的损失函数为二次函数形式．LSSVM丧失了标准支持向量机的稀疏性,为使LSSVM具有稀疏性,从统计分析的角度出发,应用主成分分析的方法,对样本集进行特征提取,消除变量间的相关性。选取训练样本中分类作用最大的若干样本个体作为支持向量,并将非支持向量上的分类信息转移至支持向量上．提出新的LSSVM稀疏化算法——基于主成分分析的最小二乘支持向量机算法。实验结果表明,由此构建的稀疏LSSVM分类器保持了支持向量机的良好分类性能．而稀疏率相对高,其支持向量数甚至少与标准支持向量机,明显提高了LSSVM的分类效率和实时性。     

一种基于混合二叉树结构的多类支持向量机分类算法

为提高多类支持向量机的分类效率,提出了一种基于混合二叉树结构的多类支持向量机分类算法。该混合二叉树中的每个内部结点对应一个分割超平面,该超平面通过计算两个距离最远的类的质心而获得,即该超平面为连接两质心线段的垂直平分线。每个终端结点(即决策结点)对应一个支持向量机,它的训练集不再是质心而是两类(组)样本集。该分类模型通常是超平面和支持向量机的混合结构,其中超平面实现训练早期的近似划分,以提升分类速度;而支持向量机完成最终的精确分类,以保证分类精度。实验结果表明,相比于经典的多类支持向量机方法,该算法在保证分类精度的前提下,能够有效缩短计算时间,提升分类效率。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate