裸光纤光栅及光纤力锤在大桥模型试验中的应用

经缩尺比例后,大跨度悬索桥模型的构件一般变得很细小,尺寸大的传感器无法或不宜安装在结构模型上,尤其是需作动力试验的模型,附加大量传感器及电缆线的质量、刚度和阻尼会严重影响试验的结果.为解决此问题,该文采用细柔的裸光纤光栅测量直径仅0.5mm细钢丝吊索及其他细小构件的应变.为获得光纤所测应变的传递函数,研制了激振用的光纤...     

Ignition Pattern Analysis for Automotive Engine Trouble Diagnosis Using Wavelet Packet Transform and Support Vector Machines

Engine spark ignition is an important source for diagnosis of engine faults.Based on the waveform of the ignition pattern,a mechanic can guess what may be the potential malfunctioning parts of an engine with his/her experience and handbooks.However,this manual diagnostic method is imprecise because many spark ignition patterns are very similar.Therefore,a diagnosis needs many trials to identify the malfunctioning parts.Meanwhile the mechanic needs to disassemble and assemble the engine parts for verification.To tackle this problem,an intelligent diagnosis system was established based on ignition patterns.First,the captured patterns were normalized and compressed.Then wavelet packet transform(WPT) was employed to extract the representative features of the ignition patterns.Finally,a classification system was constructed by using multi-class support vector machines(SVM) and the extracted features.The classification system can intelligently classify the most likely engine fault so as to reduce the number of diagnosis trials.Experimental results show that SVM produces higher diagnosis accuracy than the traditional multilayer feedforward neural network.This is the first trial on the combination of WPT and SVM to analyze ignition patterns and diagnose automotive engines.     

Evolutionary programming using a mixed mutation strategy

Different mutation operators have been proposed in evolutionary programming, but for each operator there are some types of optimization problems that cannot be solved efficiently. A mixed strategy, integrating several mutation operators into a single algorithm, can overcome this problem. Inspired by evolutionary game theory, this paper presents a mixed strategy evolutionary programming algorithm that employs the Gaussian, Cauchy, Lévy, and single-point mutation operators. The novel algorithm is tested on a set of 22 benchmark problems. The results show that the mixed strategy performs equally well or better than the best of the four pure strategies does, for all of the benchmark problems.     

香港公共房屋承建商表现评价与分析

住宅建设施工中承建商的表现对工程质量有十分重要的影响。根据香港政府推行的“承建商表现评价体系”（PASS），对承建商质量表现的总体趋势进行了评价；同时，对PASS在施工期间的变化、PASS分与工期的关系进行了剖析；并以市场份额为基础，对1994年－1998年间41家不同规模的承建商的质量表现进行了分析，结果表明，尽管ISO9000国际标准被强制推行，但质量持续改进的预期目标并未实现。     

在线自适应网络异常检测系统模型与算法

随着因特网等计算机网络应用的增加,安全问题越来越突出,对具有主动防御特征的入侵检测系统的需求日趋紧迫.提出一个轻量级的在线自适应网络异常检测系统模型,给出了相关算法.系统能够对实时网络数据流进行在线学习和检测,在少量指导下逐渐构建网络的正常模式库和入侵模式库,并根据网络使用特点动态进行更新.在检测阶段,系统能够对异常数据进行报警,并识别未曾见过的新入侵.系统结构简单,计算的时间复杂度和空间复杂度都很低,满足在线处理网络数据的要求.在DARPAKDD99入侵检测数据集上进行测试,10%训练集数据和测试集数据以数据流方式顺序一次输入系统,在40s之内系统完成所有学习和检测任务,并达到检测率91.32%和误报率0.43%的结果.实验结果表明系统实用性强,检测效果令人满意,而且在识别新入侵上有良好的表现.     

Learning by local kernel polarization

The problem of evaluating the quality of a kernel function for a classification task is considered. Drawn from physics, kernel polarization was introduced as an effective measure for selecting kernel parameters, which was previously done mostly by exhaustive search. However, it only takes between-class separability into account but neglects the preservation of within-class local structure. The ‘globality’ of the kernel polarization may leave less degree of freedom for increasing separability. In this paper, we propose a new quality measure called local kernel polarization, which is a localized variant of kernel polarization. Local kernel polarization can preserve the local structure of the data of the same class so the data can be embedded more appropriately. This quality measure is demonstrated with some UCI machine learning benchmark examples.     

基于并行约简的概念漂移探测

数据流挖掘是当前数据挖掘研究的一个热点,概念漂移检测是数据流挖掘的一个重要研究方向.虽然有不少概念漂移的探测方法,但是它们都有一些共同的缺陷:没有整体上删除冗余属性以及利用外部属性去探测概念漂移(比如利用对外部数据的分类准确率)等.利用粗糙集和F-粗糙集的基本原理和基本方法,把数据流中的滑动窗口当成决策子表簇,提出了一种对数据流进行并行约简、整体删除冗余属性的方法,并运用并行约简后数据流决策子表簇中属性重要性的变化探测概念漂移现象.与传统的方法不同,新方法利用数据的内部特性对概念漂移进行探测.实验结果显示,该方法能够有效地整体删除冗余属性、探测概念漂移现象,并且基于互信息的属性重要性在概念漂移探测效果方面比基于正区域的属性重要性要好些.     

基于支持向量机的手写体相似字识别

本文提出对手写相似汉字进行识别的支持向量机方法。该方法与人工神经网络一样适用于小规模分类,但由于支持向量机依据结构风险最小化原则,因此泛化能力更强。并且,由于支持向量机算法是一个凸二次优化问题,能够保证找到的极值解就是全局最优解。本文用支持向量机算法对三组手写相似汉字进行了识别,取得了较好的结果。     

支持向量机多专家决策算法

多专家决策算法是对多个专家的决策做出综合决策,使决策更符合实际情况.通常的算法使用各专家决策的加权求和法,由于各专家的权值在不同的情况下会有所不同,因此难以应用.本文提出采用基于支持向量机的非线性回归法进行综合决策,克服了权值变化的问题.多专家决策的另一途径是选取最佳的专家决策,本文采用基于支持向量机的非线性分类的方法,可以在不同情况下选取相应的最佳专家决策.本文提出的算法用于"隧道工程岩石力学参数综合处理系统",对若干子系统的结果进行综合,解决了专家权值变化的问题,取得了较精确的结果.