小波包分解及其能量谱在发动机连杆轴承故障诊断中的应用

论述了波波包分解及其能量谱处理发动机连杆轴承故障的原理与方法,结合传统断火诊断法的思想,应用小波包能量谱直观地识别出故障的特征频带,并进行量化分析,结果证明了这种方法比传统的付立叶分析方法具有更大的优越性及现实的应用价值。     

尺度-小波能量谱在滚动轴承故障诊断中的应用

针对滚动轴承故障振动信号的特点，构造脉冲响应小波，采用连续小波变换的方法来提取滚动轴承故障振动信号的特征，在此基础上提出了一种滚动轴承故障诊断方法：尺度-小波能量谱比较法。通过对具有外圈缺陷、内圈缺陷的滚动轴承振动信号的分析，说明尺度-小波能量谱比较法不仅能检测到滚动轴承故障的存在，而且能有效地识别滚动轴承的故障模式。     

时间-小波能量谱在滚动轴承故障诊断中的应用

为滚动轴承故障诊断提供了一种新途径，针对滚动轴承故障振动信号的特点，构造脉冲响应小波，采用连续小波变换的方法来提取滚动轴承故障振动信号的特征，在此基础上提出了一种滚动轴承故障诊断方法：时间-小波能量谱自相关分析法。通过对滚动轴承具有外圈缺陷、内圈缺陷的情况下振动信号的分析，说明时间-小波能量谱自相关分析法不仅能检测到滚动轴承故障的存在，而且能有效地识别滚动轴承的故障模式。     

小波包分析在齿轮故障诊断中的应用

基于小波包对信号的高分辨率分解和重构能力,把信号分解到不同频段,然后选择有效频段进行故障信号重构,分离出故障信息。通过对含有周期冲击的信号进行分解处理,展示了小波包分析在特征提取中的优点。通过对减速箱齿轮故障信号进行降噪、分解处理,表明该方法可以有效地提取故障信号中的周期冲击成分。     

小波分析在印刷机故障诊断中的应用

本文介绍了小波变换的原理及在印刷机故障诊断中的应用,利用小波包分析了其机械传动系统的故障。结果显示,同傅里叶变换和傅里叶变换(STFT)相比,小波变换及小波包变换是更有效的印刷机故障诊断方法。     

五滚柱式定向离合器故障诊断的小波包变换方法

论述了小波包分解及其能量谱处理五滚柱式定向离合器故障的原理与方法。应用小波包分解及其能量谱直观地识别出故障的特征频带,并进行了量化分析。结果表明,小波包及小波包分解能量谱比传统的傅立叶分析方法具有更大的优越性和价值。     

小波分析在自行火炮变速箱滚动轴承故障诊断中的应用

本文对某自行火炮变速箱中的滚动轴承进行故障诊断研究.分析了自行火炮变速箱中滚动轴承典型故障信号特征,介绍了小波分析工程应用的基本理论,最后研究了在发动机振动、齿轮啮合振动等大背景噪声下,利用小波分析方法有效地提取滚动轴承故障特征的方法,并通过实验结果分析验证了方法的可行性.     

小波包在提升机减速箱故障诊断中的应用

本文简述了小波变换的基本原理及利用小波包对振动信号进行分解的方法。小波分析良好的时－频局部化特性,为实现对振动信号在不同频率范围内对应不同零部件故障特征信息的分离和提取,及机械故障诊断提供了有效的分析手段。文中给出了利用小波包在煤矿提升机主减速箱故障诊断中提取微弱故障特征的实例。     

小波包能量谱和BP神经网络在波纹管压浆超声检测中的应用

针对小波分析在信号处理的局限性,将小波包分析和反向传播(Back Propagation,BP)神经网络相结合,提出一种基于小波包能量谱和BP神经网络的波纹管压浆超声检测方法.采用超声检测方法接收波纹管模型的回波信号,以小波包分解后各子频带的能量作为检测特征,当波纹管内部出现脱落时,检测特征会发生变化,最后将特征输入B...     

基于高斯线调频小波变换能量谱的齿轮故障诊断

提出了一种基于高斯线调频小波变换诊断齿轮故障的新方法。线调频小波变换是信号的时间－频率－尺度变换，具有比小波变换及其它时频分析方法更强的非平稳信号分析功能。利用高斯线调频小波变换作齿轮振动信号的能量谱估计，可提取调制边频带结构，识别故障模式。试验结果表明这种方法可有效应用于齿轮局部故障诊断中。     

Simplified method for evaluating energy loss in vehicle collisions

A method is proposed for the evaluation of energy loss in road vehicle collisions. The energy loss evaluation is an essential task to reconstruct the dynamics of a road accident. The proposed method combines the simplicity of visual evaluation, typical of the method based on EES (equivalent energy speed), with flexibility, in order to evaluate the energy loss on any kind of vehicle deformation profile, of the methods based on measuring residual crush.The method is based on linearizing the damage profile, so that it is possible to predetermine the analytical expression of the kinetic energy loss in relation to only two parameters that characterise the shape of the damage. The stiffness of the vehicle is determined by estimating the geometric parameters of the damage starting from a photograph of generic damage, with documented EES, on a vehicle of the same model as the one under investigation.The proposed method was validated performing crash tests and using data from crash tests found in the literature. The method estimate with sufficient accuracy the kinetic energy loss in deformation on vehicles. The method, thanks to its simplicity and versatility, can constitute a valid alternative to the classic procedures for evaluating energy loss commonly utilised.     

小波分析与傅里叶分析的比较及其在故障诊断中的应用

小波分析是傅里叶分析的发展与延拓。本文首先对小波分析与傅里叶分析的概念及特征进行比较，然后简要论述了这两种分析方法在故障诊断中的应用。     

The epidemiology of fatal motor vehicle accidents in Kuwait

The main objectives of this study are to present data on fatal motor vehicle accidents in Kuwait with a view to find out the principal epidemiological features, establish a baseline for future evaluation, use international death rates to compare Kuwait with other countries and offer specific recommendations as to how the risks involved can be reduced. The epidemiology of all fatal accidents which had occurred in Kuwait between 1 January 1977 and 31 December 1978 are analysed. This two-year series, which includes 726 accidents and represents 1.7% of all types of accidents, resulted in 803 deaths (7.3% of the national deaths toll) and 1175 injuries. The death rates per hundred million vehicle kilometers of travel, per 100,000 registered motor vehicles and per 100,000 resident population in 1978 were about 8.5, 84.8 and 31.7 respectively. These figures reveal significantly higher rates than in some industrialized countries, thus ranking motor vehicle accidents among the four leading causes of death and probably as the commonest single cause of death in Kuwait. The study shows that children under the age of 15 yr contributed 26.2% of all motor vehicle fatalities. 40.9% of pedestrian deaths (55.2% of the series), 25% of pedal-cyclist deaths, 6.3% of motorcyclist deaths and 1.2% of driver deaths. It also confirms the importance of the motor vehicle-pedestrian type of accident (58.3%) and the over-representation of buses, trucks and motorcycles with respect to involvement in fatal accidents as compared to their relative ratios of registered vehicles. The principal recommendations call for the formation of a National Council for Road Safety, the establishment of intensive roadside care, traffic education of road users and at risk groups, improvement of the environment and the firm enforcement of the law to curb the toll of this killer disease in a traditional country undergoing rapid modernization like Kuwait.     

小波极大模方法在旋转机械故障诊断中的应用研究

通过小波变换奇异性检测理论,利用连续小波变换提取极大模值线并求取Lipschitz指数,提取转子每转中Lipschitz指数的平均个数和全部Lipschitz指数的平均值作为转子故障振动信号的奇异性特征。通过BP神经网络对转子不平衡、不对中、油膜涡动、摩碰和无故障5种状态进行分类识别,取得了较好的效果。     

我国新能源汽车空调技术专利发展概况

在追求节能、环保的大趋势下,采用燃料电池、混合动力、氢能、太阳能等作为驱动力的新能源汽车已经成为全球汽车产业的必然发展方向。新能源的使用会使汽车结构出现相应变化,因此,新能源汽车空调技术也需要配套发展应运而生。本文对我国新能源汽车空调专利技术发展概况作出了总结、分析,让读者对该领域技术发展现状有所了解。     

Odontoid fracture in motor vehicle environments

The National Automotive Sampling System (NASS) and Crash Injury Research and Engineering Network (CIREN) databases were used in an analysis of odontoid fracture in motor vehicle crashes. NASS data were evaluated for the years 1996-2002, and CIREN from 1996 to 2003. Out of 58 fractures, 38 were identified in the NASS and 20 in the CIREN databases. There were 3108 weighted cases in the NASS database. Frontal impacts (11:00 to 1:00 h) were most commonly associated with the injury in both databases. Although male and female occupants sustained the injury, females were shorter in stature, older in age, lighter in weight, and crashes were less severe (lower change in velocity) when female occupants were involved in trauma. In both databases, pure odontoid fracture and facet/lamina fracture accounted for approximately one-third of the cases, and a majority of impacts were associated with changes in velocity less than 56 km/h. Although vehicle model years ranged from 1976 to 2002, recent model years were more frequently associated with CIREN data. In the CIREN database, type II odontoid fracture was the most common, but no particular mechanism of injury dominated; such information was not available in the NASS database. To ameliorate odontoid fracture, focus should be on frontal impacts. Because different types of odontoid fracture are not included in the current Abbreviated Injury Scale, appropriate coding schemes should be developed to classify this injury. The CIREN database is unique because it provides important clinical information, i.e., fracture type, and the associated mechanism of injury. The mechanism component in any epidemiologically based injury analyses is valuable to advance improvements in vehicle crashworthiness.     

基于自适应谐波小波和能量熵的转子系统故障诊断研究

针对转子系统非平稳振动时故障特征难以准确提取的问题,提出一种基于自适应谐波小波和能量熵的转子系统故障诊断方法。首先,采用连续谐波小波方法分解转子信号,克服二进制谐波小波包分解不能任意选取感兴趣频段的缺限,同时在分解过程中通过时间尺度变换的方式消除信号采集过程中不同转速及采样频率的影响;然后,通过设定合理的分解参数,提取出表征转子系统的故障特征信息并构建故障模式矩阵,得到转子系统早期局部碰摩、全周碰摩、油膜涡动和油膜振荡等4种工况下的能量熵值;最后,将特征向量输入支持向量机(support vector machine,SVM)判断出转子系统的故障类型。试验结果表明:该方法可以有效用于转子系统的故障诊断。     

机动车前照灯检测仪校准器的光轴角测量方法

研制的检测装置实现了对机动车前照灯检测仪校准器光轴角的检测。该检测装置采用光电检测和计算机数据处理技术相结合的方法,完成数据自动采集,并进行光轴角的示值误差计算。该方法替代使用坐标板的机械测量方法,其测量不确定度满足JJG 967-2001的要求,极大地提高了检测仪的检测效率。     

Severe-to-fatal head injuries in motor vehicle impacts

Severe-to-fatal head injuries in motor vehicle environments were analyzed using the United States Crash Injury Research and Engineering Network database for the years 1997-2006. Medical evaluations included details and photographs of injury, and on-scene, trauma bay, emergency room, intensive care unit, radiological, operating room, in-patient, and rehabilitation records. Data were synthesized on a case-by-case basis. X-rays, computed tomography scans, and magnetic resonance images were reviewed along with field evaluations of scene and photographs for the analyses of brain injuries and skull fractures. Injuries to the parenchyma, arteries, brainstem, cerebellum, cerebrum, and loss of consciousness were included. In addition to the analyses of severe-to-fatal (AIS4+) injuries, cervical spine, face, and scalp trauma were used to determine the potential for head contact. Fatalities and survivors were compared using nonparametric tests and confidence intervals for medians. Results were categorized based on the mode of impact with a focus on head contact. Out of the 3178 medical cases and 169 occupants sustaining head injuries, 132 adults were in frontal (54), side (75), and rear (3) crashes. Head contact locations are presented for each mode. A majority of cases clustered around the mid-size anthropometry and normal body mass index (BMI). Injuries occurred at change in velocities (ΔV) representative of US regulations. Statistically significant differences in ΔV between fatalities and survivors were found for side but not for frontal impacts. Independent of the impact mode and survivorship, contact locations were found to be superior to the center of gravity of the head, suggesting a greater role for angular than translational head kinematics. However, contact locations were biased to the impact mode: anterior aspects of the frontal bone and face were involved in frontal impacts while temporal-parietal regions were involved in side impacts. Because head injuries occur at regulatory ΔV in modern vehicles and angular accelerations are not directly incorporated in crashworthiness standards, these findings from the largest dataset in literature, offer a field-based rationale for including rotational kinematics in injury assessments. In addition, it may be necessary to develop injury criteria and evaluate dummy biofidelity based on contact locations as this parameter depended on the impact mode. The current field-based analysis has identified the importance of both angular acceleration and contact location in head injury assessment and mitigation.     

Daily fluctuations in Honolulu motor vehicle accidents

Changes in daily motor vehicle accidents during 1990 are examined for the City and County of Honolulu. Adjusting for changed reporting criteria, daily accidents fluctuate according to an interaction between traffic volume, weekday travel patterns, holidays and weather. Fridays, particularly, and Saturdays have more daily accidents. Minor holidays generate more daily accidents, but major holidays generate fewer daily accidents, primarily because of lower traffic volume. Rainfall increases the risk of accidents substantially. The interaction between afternoons and rainfall is particularly dangerous. Unemployment also appears to reduce daily accidents.