小波变换在结构损伤识别中的应用研究

针对土木工程结构的复杂性和数据的不完备性，以小波分析为理论基础，结合多尺度分析理论和数值模拟，对结构损伤识别进行了研究。主要分析了结构动力参数在损伤后的变化特征，对单自由度框架的加速度信号进行小波分析，得到结构损伤的时刻；研究了利用空间域信息对结构损伤位置的识别问题，对带裂缝悬臂梁的变形曲线进行小波变换，判定了结构损伤位置。     

Estimating the ride quality characteristics of vehicles with random decrement analysis of on-the-road vibration response data

This paper describes the application of a practical analytical technique based on the random decrement method to estimate the rigid sprung mass dynamic characteristics (frequency response function) of road vehicles using only vibration response data during constant-speed operation. A brief history and development of the random decrement technique is presented, along with a summary of work undertaken on optimal parameter selection to establish the random decrement signature. Two approaches to estimate the dynamic characteristics from the random decrement signature are described and evaluated. A custom, single-wheeled vehicle (physical quarter car) was commissioned to undertake a series of on-the-road experiments at various nominally constant operating speeds. The vehicle, also instrumented as an inertial profilometer, simultaneously measured the longitudinal pavement profile to establish the vehicle's actual dynamic characteristics during operation. The main outcome of the paper is that the random decrement technique can be used to provide accurate estimates of the sprung mass mode of the vehicle's dynamic characteristics for both linear and nonlinear suspension systems of an idealised vehicle.     

京港澳高速公路河北段改扩建工程研究

介绍了原路基宽度和改扩建后新路基宽度。描述了原有路基状况、改扩建路基用土石方数量和来源及对特殊路基采用的技术措施、路基防护手段、新建及改造路段路面结构,为同类工程提供技术参考。     

A framework for short-term traffic flow forecasting using the combination of wavelet transformation and artificial neural networks

The main objective of this paper is to develop a framework for short-term traffic flow forecasting models with high accuracy. Due to flow oscillations, the real-time information presented to the drivers through variable message signs, etc., may not be valid by the time the driver reaches the location. On the other hand, not all compartments of the flow signal are of same importance in determining its future state. A model is developed to predict the value of traffic flow in near future (next 5–35?minutes) based on the combination of wavelet transformation and artificial neural networks. This model is called the hybrid WT-ANN. Wavelet transformation is set to denoise the flow signal, i.e., filtering the unimportant fluctuations of the flow signal. Unimportant fluctuations are those that have little or no effect on the future condition of the signal. The neural network is set and trained to use previous data for predicting future flow. To implement the system, traffic data of US-101 were used from Next Generation Simulation (NGSIM). Results show that removing the noises has improved the accuracy of the prediction to a great extent. The model was used to predict the flow in three different locations on the same highway and a different highway in a different country. The model rendered highly reliable predictions. The proposed model predicts the flow of next 5?min on the same location with 2.5% Mean Absolute Percentage Error (MAPE) and of next 35?min with less than 12% MAPE. It predicts the flow on downstream locations for next 5?min with less than 8% MAPE and for the different highway with 2.3% MAPE.     

基于DSP的水下目标识别嵌入式系统

水下目标识别系统是海洋开发的关键组成部分,而利用声呐对目标物进行定位跟踪是水下目标识别系统中最重要的技术。本文首先分析水下目标识别系统的基本原理及组成,重点研究水下声呐目标识别技术中的基于形状及纹理等特性对识别精度的影响,最后优化小波变换对目标物声呐图像的提取特征算法,通过对声呐特性的分析提出一种小波提升分析法,并构造基于DSP嵌入式系统。     

基于拟牛顿迭代的分数阶Fourier变换最佳阶次的搜索方法研究

针对如何快速确定分数阶Fourier变换最佳阶次的问题,在分析拟牛顿迭代法基本原理的基础上,研究了其在这一实际应用中的具体实现步骤.通过仿真实验展现了拟牛顿迭代法搜索分数阶Fourier变换最佳变换阶次的收敛过程,分析讨论了其在实际应用中存在的利弊.     

视觉刺激情感变化β波同步分析

针对由视觉刺激产生情感变化问题,运用事件相关去同步化和同步化方法分析不同情感的视觉刺激下左右脑前额和中央区域的活动状态和活动强度.通过去同步化和同步系数零一法标记特定时间段来判断受刺激阶段的活动状态,并在此基础上通过左右脑功率谱差值绝对值判断活动区域的强烈程度.结果表明视觉刺激为高兴时,男性和女性大脑活动区域相同但前额区域左右脑活动强度有区别;视觉刺激为不高兴时,男性两区域均为活动状态但强度有区别,女性两区域均为惰性状态.进而推断出:男性对高兴和不高兴的视觉刺激反应均比较明显而女性只对高兴的视觉刺激明显.     

基于小波融合的车牌模糊图像复原算法

为了更有效的实现交通信息采集,提出了一种基于小波融合的车牌图像超分辨率方法.首先分析了低分辨率图像的降质原因,主要降质因素包括:图像的形变、模糊和欠采样,根据这些降质因素建立了降质模型,分析降质模型,得出本文方法的理论模型.然后针对交通图像的特点,对形变、模糊和欠采样3个问题进行探讨,得出主要参数的估计方法.并对小波融...     

基于振动信号和小波变换的转速测量方法研究

通过分析发动机振动信号的基频与转速之间的数学关系,设计了基于LabVIEW的采集系统,利用小波变换的方法提取振动信号的基频,提出了一种精度高、易于实现的发动机瞬时转速检测算法,并通过试验验证了该方法的可行性.经过与实际转速比较,该算法的误差率在1%以内,准确性和鲁棒性均符合测量求,具有重要的实用价值.     

工业时窗小波降噪调制连续线性动力学系统参数直接辨识

在时窗内对噪声干扰的信号进行小波降噪,对降噪数据调制积分得等价的代数方程,利用最小二乘算法,进行线性动力学系统参数的直接估计．针对受噪声污染的系统参数估计的有偏性,借助时窗降噪调制方法构造辅助变量,提出了降噪调制辅助变量递推算法,进行了系统参数的无偏估计．仿真实验和应用实例表明,该方法具有有效性和实用性,可为工业在线辨识获得可信的系统参数提供参考．