Fault detection of vehicle suspension system using wavelet analysis

This paper presents a method based on continuous wavelet transform to detect the faults of vehicle suspension systems. The Morlet wavelet functions are employed to approach the natural frequencies of the system and the frequency components of the signal with relative maximum energy. To evaluate our method, we use a full vehicle dynamic model which has been simulated in ADAMS/CAR and validated by laboratory test results. The suspension faults have been considered due to the damage of shock absorbers (dampers) and upper damper bushings (UDBs) and assumed as the decrease in damping force and loose joints, respectively. In this paper, the incapability of the spectral analysis by using fast Fourier transform in analysis of the signals is revealed through applying the inputs that include transient characteristics and then wavelet transform employed to achieve more proper results. A swept frequency is applied as an input to the wheels that simulates the road irregularities. After detection of faulty sections of the system using signal energy distribution, the defects of damper and UDBs are distinguished from each other through observing the changes of natural frequencies and corresponding energy amplitudes.     

某港重力式墩台压顶方块开裂原因分析

通过对某港重力式墩台压顶方块开裂原因的分析,阐述了一种罕见的支撑状态改变引起墩台上构件破损的因素。     

小波变换用于列车振动信号消噪的研究

小波变换的重要应用之一就是用于信号的消噪。通常从列车上采集的振动信号都混有大量的噪声 ,现采用非线性小波阈值法对信号进行消噪 ,并利用阈值处理后的小波系数重建信号 ,从而得到有用的信号波形。实验结果表明该方法能有效的去除噪声 ,可靠性高 ,特别适用于信号中混有白噪声的情况     

基于 Keystone 变换的俯冲加速运动 SAR 成像算法

俯冲加速条件下的SAR成像算法是当前SAR成像领域中一个热门研究课题。受到加速度的影响,其距离方程不再是单纯的双曲线形式,从而导致无法根据驻定相位原理求得俯冲加速SAR回波的二维频谱解析表达式。因此,传统SAR频域成像算法不再适用于俯冲加速SAR成像。论文从SAR距离徙动特性着手,利用Keystone变换实现对俯冲加速SAR的线性徙动校正,从而实现距离向和方位向的二维解耦合,得到最终的SAR聚焦图像。     

暗河地区高填路堤筋墙方式拓宽重载动力响应模型试验

利用重载动力响应模型试验装置,对路堤下伏溶洞的变形破坏机理与稳定性进行了深入分析,归纳出路基下不同部位变形破坏特征,分析了暗河漏斗地区高填路堤的稳定性。得出了路基路面在不同荷载作用下相应产生变形,传递到路面下各结构层并引起相应沉降变形,最终导致了路面塌陷和坡脚的破坏,确定暗河地区高填路堤筋墙方式拓宽,为暗河地区高填路堤整治方案奠定了基础。     

公路货运抽样调查数据自动采集系统应用措施研究

公路货运抽样调查数据自动采集系统是利用科学技术进行数据自动采集与传输,并能避开人为干扰因素.具有很好的推广应用价值.     

A High-performance Low Cost Inverse Integer Transform Architecture for AVS Video Standard

A high-performance, low cost inverse integer transform architecture for advanced video standard (AVS) video coding standard was presented. An 8×8 inverse integer transform is required in AVS video system which is compute-intensive. A hardware transform is inevitable to compute the transform for the real-time ap-plication. Compared with the 4×4 transform for H.264/AVC, the 8×8 integer transform is much more complex and the coefficient in the inverse transform matrix Ts is not inerratic as that in H.264/AVC. Dividing the Ts into matrix S8 and R8, the proposed architecture is implemented with the adders and the specific CSA-trees instead of multipliers, which are area and time consuming. The architecture obtains the data processing rate up to 8 pixels per-cycle at a low cost of area. Synthesized to TSMC 0.18 μm COMS process, the architecture attains the operating frequency of 300 MHz at cost of 34 252 gates with a 2-stage pipeline scheme. A reusable scheme is also introduced for the area optimization, which results in the operating frequency of 143 MHz at cost of only 19 758 gates.     

Hilbert-Huang变换在桥梁振动分析中的应用

提出将Hilbert Huang 变换的信号处理方法应用于桥梁振动分析中。此方法是通过经验模态分解(EMD)将一复杂的原始数据序列分解成一组本征模函数(IMF)和一个残余项,然后再对每一个IMF进行Hil bert变换。这样所得到的信号幅度和瞬时频率都是时间的函数,即获得了幅度的频率时间分布,称为Hilbert Huang幅度谱,进而得到Hilbert边界谱。文中利用Hilbert Huang变换对南京桥有列车通过时的实测加速度响应进行了处理与分析,结果表明该方法可行、有效。     

基于霍夫变换的全景图中建筑物识别方法

提出了一种能够自动识别全景图中建筑物轮廓的方法.首先利用Canny算子获得边缘图像,使用霍夫变换算法提取出边缘图像中的直线.然后检测各条直线之间的位置关系,由于全景图尺寸较大,采用了局部化原理来进行检测.再根据直线之间的位置关系生成直线关系图.最后遍历直线关系图得到封闭几何图形,从而识别出大规模全景图中的建筑物轮廓,为进一步的全景图中建筑物三维建模提供素材.算法分析和实验结果表明,该方法对于几何形状规则的建筑物能够较好的识别.     

人车路综合风险场模型构建及驾驶风格评估

为帮助驾驶人正确认知自身的安全驾驶能力，揭示“人-车-路”相互作用关系并衡量各要 素对车辆驾驶安全性的影响，构建了考虑驾驶风格因子的综合风险场模型。首先，针对现有风险 场模型在人因要素刻画不足，将车辆加速度方差和方向盘转角方差转化为驾驶风格因子，表征驾 驶人潜在驾驶习惯；然后，根据事故风险的突发性和短时性特征，利用希尔伯特-黄变换(HilbertHuang Transform, HHT)将驾驶全域风险分解为平稳阶段和局部突变阶段风险信号能量，作为评 价驾驶能力内在属性的关键依据；最后，开展行人横穿风险场景的驾驶模拟试验验证。结果表 明：驾驶风险能量在空间形态上呈“椭圆形”圈层分布，沿物理轮廓中心高边缘低，风险演变过程 能量大小“爬山式”递增效应显著。对风险能量聚类可获得比主观问卷更加细致可量化的分类结 果，对比发现，驾驶人存在“认知-操纵”偏差(问卷安全型-模型危险型/危险倾向)同时丰富的驾驶 经验对薄弱的安全意识有补偿作用(问卷危险型-模型安全型/安全倾向)。研究成果可以为识别 危险驾驶人群，提高安全驾驶能力提供一种新方法。