基于改进的LVQ神经网络的发动机故障诊断

学习向量量化(LVQ)神经网络可以通过监督学习完成对输入向量模式的准确分类,提出了一种基于改进的LVQ神经网络的发动机故障诊断方法,介绍了LVQ神经网络及其改进的学习算法。以长城哈佛GW2.8TC型发动机为实验对象,让发动机在怠速状况下,对发动机进行故障设置,利用金德KT600电脑故障诊断仪采集发动机数据流,运用改进的LVQ神经网络建立诊断模型,诊断结果表明,改进的LVQ神经网络能对发动机故障做出正确分类,准确率比较高。     

基于PC的齿轮泵实验台设计

为了获得齿轮泵的特性曲线,以PC机为基础设计了齿轮实验台。对实验台液压管路系统、计算机硬件线路以及LabWindows/CVI上位机测控软件进行详细设计。测试表明该实验台运行稳定,获取的数据可以得到齿轮泵的特性曲线,能够满足科研、教学要求。     

基于PNN神经网络的电控发动机故障诊断

PNN是前馈型神经网络,具有强大的非线性模式分类能力。提出运用PNN神经网络对发动机电控系统进行故障诊断的方法,介绍了PNN神经网络及其工作原理,以伊兰特汽车发动机电控系统为研究对象,让发动机在怠速情况下,并对其进行故障设置,运用金德KT600故障诊断仪采集发动机故障数据流,利用PNN神经网络建立诊断模型,并对网络诊断模型进行验证,诊断结果完全正确,且训练速度非常快。实验结果表明PNN神经网络具有较强的泛化能力和实用价值。     

计算机安装、调试和维修人员初级考核复习思考题(3)

选择题(续)86.计算机组装完毕,加电开机后,主机开始工作,但是显示器无任何显示。最可能的原因是_。 A.计算机的CPU有故障 B.计算机主板有故障 C.显示器有故障 D.主板上的显卡安插不到位或是显卡与显示器不兼容87.计算机组装完毕,所有连接无误,加电开机后却检测不到硬盘或光驱,很可能的原因是_。A.厂商提供的硬盘或光驱有故障B.计算机CPU损坏C.计算机内部的出厂预设置有误D.硬盘或光驱的跳线帽设置不正确88.计算机组装完毕,要想对CMOS参数进行设置,开机后,多数情况下应按下的键是_。A.Del B.Tab C.Shift D.Ctrl89.目前,安…     

基于BP神经网络的电控发动机故障诊断

针对汽车发动机电控系统结构的复杂性,提出用BP神经网络进行故障诊断的方法。以北京现代05款途胜G4GC型发动机电控系统为实验,并对其进行故障设置,采集发动机故障数据流,运用BP神经网络构建诊断模型,并且改变BP训练方法。诊断结果表明用BP神经网络诊断发动机电控系统故障是行之有效的,具有较好的应用前景。     

汽车电控发动机常见故障分析

随着汽车电控技术的发展进步,汽车电控发动机系统也日益复杂,汽车发动机的故障发生率增大,故障维修的难度增加,也形成了汽车维修行业领域近年来新的难题。从实践经验中得知,汽车电控发动机故障的发生可能是多方面原因引起的,尤其是在油路系统和气路故障上,故障识别诊断难度大,故障发生率也较高。笔者在本文中对电控发动机常见故障进行了简要的结语分析,并对故障排除进行了探讨,旨在通过本文的研究为汽车电控发动机故障诊断与排除提供相应的指导。     

车辆GPS远程监控系统开发

为了解决车辆信贷风险控制、车辆远程位置监控、远程故障诊断、车辆行驶区域设定等问题,研究和开发了GPS远程监控系统。采用＂远程控制中心＋GPS终端＂的模式构建,整车上的GPS终端通过CAN总线与发动机ECU进行通信,实现对发动机信息的采集以及响应控制中心的远程控制命令。目前该系统已成功应用于某型号的电控发动机,实现了位置监控、整车行驶路线设置、发动机油耗统计、发动机信息远程诊断、远程坡行控制等功能。     

用于教学的电气实训系统的设计

本文介绍了一种用于教学的智能化电气实训系统的工作原理和操作方法,对提高高职院校机电一体化及电气自动化专业学生的动手操作能力有较大的帮助。使用该实训系统时,学生只需按照电气原理图在接线端子排上完成接线即可,避免了直接在电气元件上频繁拆装,因而可提高电气实训台的可靠性,延长其使用寿命。经扩充后的智能化电气实训系统,可通过计算机设置故障及代码,便于学生分析和排查故障训练,并且可以作为技能鉴定考核装置。     

汽车传感器分类

车用传感器是汽车计算机系统的输入装置，它把汽车运行中各种工况信息，如车速、各种介质的温度、发动机运转工况等，转化成电讯号输给计算机，以便发动机处于最佳工作状态。车用传感器很多，判断传感器出现的故障时，不应只考虑传感器本身，而应考虑出现故障的整个电路。因此，在查找故障时，除了检查传感器之外，还要检查线束、插接件以及传感器与电控单元之间的有关电路。下面我们来认识一下汽车上的主要传感器。     

汽车发动机机械系统维修教学之探讨

汽车发动机机械系统维修是高等职业院校汽车维修类专业的重要专业课,是以汽车发动机维修岗位的主要工作任务为重点而设置的一们课程,具有极为重要的地位。本文论述了汽车发动机机械系统维修教学的思路,解析了汽车发动机机械系统维修教学案例,并探讨了汽车发动机机械系统维修教学评价策略。     

仿生小波变换在飞机发动机故障诊断中的应用

飞机发动机是一种复杂的旋转机械,故障种类多而且难以辨别。为了保证飞行安全,对飞机发动机的故障进行正确、快速地检测,文中应用仿生小波变换对某型涡轮风扇发动机在飞行中空中停车的振动信号作了分析。实验结果表明,对在频谱图上难以找到其相应的明显频率成分的准周期故障信号,利用仿生小波变换(BWT)的自适应调节功能,使得故障信号的细节成分更加地突出,对比该频率和故障情况下计算出的特征频率,可以找出故障的原因。     

Diagnosis of multiple sensor and actuator failures in automotiveengines

Unlike cases where only a single failure occurs, fault detection and isolation of multiple sensor and actuator failures for engines are difficult to achieve because of the interactive effects of the failed components. If faults all appear either in sensors only or in actuators only, many existing residual generators which provide decoupled residual signals can be employed directly to obtain proper fault detection and isolation. However, when both sensor and actuator failures occur at the same time, their mutual effects on residuals make fault isolation particularly difficult. Under such circumstances, further decision logic is required. In the paper, the authors propose a hexadecimal decision table to relate all possible failure patterns to the residual code. The residual code is obtained through simple threshold testing of the residuals, which are the output of a general scheme of residual generators. The proposed diagnostic system incorporating the hexadecimal decision table has been successfully applied to automotive engine sensors and actuators in both simulation and experimental analyses. Enhancement of the present diagnostic performance by implementing an additional sensor is also described     

Dynamic emulation of mechanical loads using a vector-controlledinduction motor-generator set

This paper addresses the problem of electronic emulation of both linear and nonlinear mechanical loads using a vector-controlled induction machine dynamometer. It is shown that a basic emulation scheme where the dynamometer torque demand is derived from the inverse dynamics of the emulated load is not generally viable, especially if the emulated load is part of a closed-loop speed control system. A new feedforward speed-tracking control scheme for the dynamometer is presented, which preserves the load dynamics and allows for emulation of a large class of nonlinear loads. An experimental rig is described using vector-controlled induction machines as the drive motor and dynamometer, and experimental results showing excellent emulation of both linear and nonlinear load dynamics are presented     

Cloud Computing Technology and Its Applications

Virtualization and distributed parallel architecture are typical cloud computing technologies. In the area of virtualization technology, this article discusses physical resource pooling, resource pool management and use. cluster fault location and maintenance, resource pool grouping, and construction and application of heterogeneous virtualization platforms. In the area of distributed technology, distributed file system and Key/Value storage engine are discussed. A solution is proposed for the host bottleneck problem, and a standard storage interface is proposed for the distributed file system. A directory-based storage scheme for Key/Value storage engine is also proposed.     

Multilayer control of an induction motor drive:A strategic step for automotive applications

Fault tolerance is a critical attribute in automotive electrical and propulsion systems. In this paper, a control scheme is presented that allows an induction motor drive system to operate in the event of multiple sensor failures. Automatic diagnosis of sensor fault and recovery is performed and used to reconfigure the drive system controls to achieve the best performance in lieu of component degradation. This approach couples a new digital delta-hysteresis regulation scheme with a model reference adaptive system scheme in order to provide fault tolerance for both phase-current and rotor position (speed) sensors. Simulation and experimental results are provided to show the effectiveness of the proposed scheme.     

基于虚拟仪器技术的主机监控系统自动测试系统设计

针对某主机监控系统故障维修难度大且缺少相应维修测试仪器和工装设备的实际情况,设计了一种基于LabVIEW的PCI总线和数据采集卡的自动测试装备并完成了具体设计工作。其采用PCI-3361进行信号的采集和控制向量的输出,通过继电器和外部接口电路实现测试单元的自动选择,利用Lab VIEW应用程序进行故障的检测、识别、定位。实验表明该测试装备工作可靠,适用性良好。     

阵列乘法器通路时延故障的内建自测试

阵列乘法器因高度集成和高速运行,容易受到时延故障的困扰.该文对阵列乘法器的通路时延故障提出了一种用累加器实现的以单跳变序列作为测试序列的内建自测试方案.已有的理论和实践表明采用单跳变测试序列比多跳变序列具有更高的测试鲁棒性.同时,该文的测试方案在测试通路覆盖率和测试向量数之间做到了兼顾.仿真结果表明这种单跳变测试序列具有高测试通路覆盖率.此外,测试生成通过系统已有累加器的复用可节省硬件成本开销.     

Hybrid learning control schemes with input shaping of a flexible manipulator system

The paper describes a practical approach to investigate and develop a hybrid iterative learning control scheme with input shaping. An experimental flexible manipulator rig and corresponding simulation environment are used to demonstrate the effectiveness of the proposed control strategy. A collocated proportional-derivative (PD) controller utilizing hub-angle and hub-velocity feedback is developed for control of rigid-body motion of the system. This is then extended to incorporate iterative learning control with acceleration feedback and genetic algorithms (GAs) for optimization of the learning parameters and a feedforward controller based on input shaping techniques for control of vibration (flexible motion) of the system. The system performance with the controllers is presented and analysed in the time and frequency domains. The performance of the hybrid learning control scheme with input shaping is assessed in terms of input tracking and level of vibration reduction. The effectiveness of the control schemes in handling various payloads is also studied.     

Integrated fault-tolerant scheme for a DC speed drive

In this paper, an active fault-tolerant control (FTC) scheme is presented with disturbance compensation. Fault-detection and compensation are merged together to propose a robust algorithm against model uncertainties. The GIMC control architecture is used as a feedback configuration for the active fault-tolerant scheme. The synthesis procedure for the parameters of the fault-tolerant scheme is carried out by using tools of robust control theory. A detection filter is designed for fault isolation taking into account uncertainties and disturbances in the mathematical model. Finally, the fault compensation strategy incorporates an estimate of the disturbances into the system to improve the performance of the closed-loop systems after the fault is detected. In order to illustrate these ideas, the speed regulation of a dc motor is selected as a case study, and experimental results are reported.     

柴油机OBD系统设计

为了开发低成本的且具有自主知识产权的OBD系统,论文针对高压共轨柴油机电控系统。选取冷却液温度传感器作为典型传感器进行故障诊断分析。设计了故障诊断电路,研究了故障诊断策略。通过MATLBASIMULINK仿真方法对故障诊断策略进行理论研究。最后在发动机试验台上进行故障诊断试验。该设计能够准确可靠的确诊故障并给出合适的处理结果。为整个OBDII系统设计提供经验。