RW22空调软卧车空气调节系统的微机控制

ＲＷ２２型空调软卧车的空气调节系统原是固定逻辑式接触器继电器控制系统，该系统可靠性差，占的空间体积大，易损坏，常因故障而停机，因此，不能满足人们对软卧车舒适性的要求，为提高软卧车空调系统的可靠性，减少故障率，采用可编程序控制器代替原控制系统中的继电器部分。文章分析了原系统控制要求，论述了用ＰＣ实现的控制过程及电气控制保护。     

盾构仿真机控制系统的设计与开发

由于盾构掘进装备和施工安全的特殊要求及施工环境的特殊性,导致绝大部分盾构掘进设备技术人员难以在实际的施工现场进行盾构关键技术的相关研究,当前研究和掌握盾构掘进技术多以模拟仿真试验作为重要方法。文中论述了在盾构掘进系统中的:刀盘控制系统、管片拼装系统以及推进系统作为设计对象进行电液控制系统开发。应用结果表明该系统性能稳定可靠,能够较为全面的展现盾构掘进过程中的控制功能,达到了系统设计的效果。     

复合地层下泥水盾构管片上浮规律及影响因素分析

针对在盾构隧道施工中经常出现的管片上浮问题,以南昌轨道交通4号线泥水盾构过江隧道为工程依托,通过数理统计方法对泥水盾构穿越不同地层时管片上浮量进行归纳分析,探讨地层参数以及盾构掘进参数对管片上浮的影响规律。研究结果表明:在全断面砂层中掘进,管片上浮量小且上浮值变化稳定;而当进入上软下硬地层和泥质粉砂岩层,管片上浮量急剧变化,尤其是在过江段中风化泥质粉砂岩中掘进,管片上浮量最大。考虑盾构掘进参数单因素影响,随着注浆压力、泥水压力和盾构推力的增大,管片上浮量均会出现增大,而掘进速度的变化对施工期间管片上浮影响较小。在掘进过程中需要结合地层特性对管片上浮影响并且对主要掘进参数进行实时调整,在一定程度上可以实现对管片上浮的有效控制。     

挖泥船分布式控制系统研究

近年来我国挖泥船技术有了较大的发展,挖泥船市场需求也日益增长,但国内挖泥船的作业控制系统技术还比较落后,严重制约挖泥船在作业中设备的效能发挥,为提高挖泥船控制系统性能及作业整体效率,本文引入分布式开放网络架构设计挖泥船控制系统的三层网络结构,提高系统通信实时性,可靠性和抗干扰能力.对与上位机系统,采用OPC模式设计web上位机软件系统,实现系统的便捷操作,提高系统的维护和管理质量,降低维护成本.     

盾构管片开裂原因分析及应对措施

管片作为盾构隧道的主体结构,其开裂必将造成隧道的质量问题,并最终影响隧道的使用寿命.通过对隧道管片在盾构掘进施工中产生的裂缝进行原因分析,提出相应的对策,对指导施工具有重要意义.     

盾构管片开裂原因分析及应对措施

管片作为盾构隧道的主体结构,其开裂必将造成隧道的质量问题,并最终影响隧道的使用寿命。通过对隧道管片在盾构掘进施工中产生的裂缝进行原因分析,提出相应的对策,对指导施工具有重要意义。     

一例船舶发电机滑油日耗量增加故障分析

船舶发电副机系统滑油耗量异常增加时,过多的滑油窜入燃烧室会造成燃烧恶化,严重污染活塞、气缸、气阀、排气道,甚至结焦造成活塞环卡死,影响安全生产。以某型号船舶发电副机滑油日耗不断增加的故障为例,分析滑油油耗增加的常见原因,进行故障排查,得出该型号船舶发电副机滑油油耗的增加并非滑油系统自身的原因,而是由于活塞环制作工艺不完善造成的。因此,在备件的购置和验收时要加强审核,择优选用。日常要对滑油消耗量、吊缸检查、活塞环搭口间隙、磨损测量等进行检查,及时发现故障,排除故障,确保船舶航行安全。     

富水硬岩地层盾构管片上浮机理及控制对策

管片上浮引发的错台、开裂是盾构隧道施工过程中的典型问题。针对长沙地铁6 号线朝芙区间管片上浮严重的地段,分析了富水硬岩地层中管片上浮的机理,并采用数值模拟的方法探究了浆液凝固时间、浆液早期弹性模量及地下水位对管片上浮的影响,结合施工过程提出控制管片上浮的对策。研究结果表明:浆液的凝固时间对管片上浮影响最大,通过调整浆液的配比,让浆液在4~6h内凝固可有效控制管片上浮;浆液的早期弹性模量对于管片上浮也有很大影响,可根据实际情况选择性质较好的浆液,其中双液浆可在30s内速凝形成很高的弹性模量,可应用于上浮严重地段,抑制管片上浮;较低的地下水压力对抑制管片上浮较有利,在盾尾每10环施作止水环箍可有效形成止水隔离带,降低地下水的影响;控制同步注浆过程保证同步注浆的质量,其中注浆压力控制在设定范围内且不能超过设定值,将理论注浆量进行调整且增加管片上部注浆比例;控制盾构的掘进姿态从而减小管片受力不均引起的上浮,同时控制盾构掘进速度能够保证盾尾空隙被同步注浆浆液有效填充。     

HXD2B型机车冷却风机故障原因分析及预防措施

HXD2B型机车是我国铁路干线主要货运机车,随着机车运用里程的增加,机车冷却风机接触器故障频发,造成机车质量不稳。针对HXD2B型机车C4修后发生的典型冷却风机接触器故障原因进行分析,提出改进和预防措施,确保机车修后质量,保障机车运用安全。     

盾构施工对盾尾浆液压力波动变化的影响

为探明盾构隧道同步注浆过程中管片壁后浆液压力不稳定变化的原因,通过对珠海马骝洲隧道工程进行现场测试及施工参数统计,获得了盾构掘进过程中管片外荷载的变化规律与注浆滞后时间;将盾尾视为充满高压液体的密闭容器,盾构推进视为改变容器的边界条件,推导了盾尾体积应变与浆液压力的关系式;并用钱江隧道及Sohpia隧道的监测结果对其适用性进行了验证. 研究结果表明:造成同步注浆过程中管片壁后浆液压力不稳定变化的因素主要包括浆液注入口压力的波动变化,管片脱离盾尾过程中浆液的扩散及施工过程中同步注浆相较于盾构行程的滞后效应;马骝洲隧道注浆相较于盾构推进的平均滞后时间为86 s,当盾尾间隙体积变量为1 × 10–4时浆液压力变化值达到了0.218 MPa,盾构机从静止到掘进的短时间内滞后效应会使管片壁后浆液压力急剧降低的现象得到了验证.      

现代汽车电控单元常见故障原因及对策

随着现代汽车电子设备的广泛应用,电控单元ECU的故障率逐年增加,同时也表现出不同于以往传统汽车电控系统的故障原因和解决方法为提高汽车电控系统的可靠性,针对一些常见的故障及其表征,结合多年来的教学成果和维修经验．对这些故障进行详尽的分析,并分别提出解决方法,可供参考。     

Binary decision diagram quantitative analysis method based on fuzzy set theory

A binary decision diagram(BDD) is a data structure that is used to represent a Boolean function.Converting fault tree into BDD can effectively simplify counting processes and improve the accuracy and effectiveness of the results. However, due to various types of uncertainties in reliability data, we cannot obtain precise failure probabilities. In order to accurately quantify the certainties and obtain much more reliable results, we use BDD method based on fuzzy set theory for reliability quantitative analysis. In this regard, we take W-axis feeding system of heavy-duty computer numerical control(CNC) machine as a project example and adopt fuzzy BDD quantitative analysis method to analyze its reliability. The analysis results(aided by computer calculation)illustrate the effectiveness of the method proposed in this paper.     

Reliability analysis of electrical system of computer numerical control machine tool based on bayesian networks

The core of computer numerical control (CNC) machine tool is the electrical system which controls and coordinates every part of CNC machine tool to complete processing tasks, so it is of great significance to strengthen the reliability of the electrical system. However, the electrical system is very complex due to many uncertain factors and dynamic stochastic characteristics when failure occurs. Therefore, the traditional fault tree analysis (FTA) method is not applicable. Bayesian network (BN) not only has a unique advantage to analyze nodes with multiply states in reliability analysis for complex systems, but also can solve the state explosion problem properly caused by Markov model when dealing with dynamic fault tree (DFT). In addition, the forward causal reasoning of BN can get the conditional probability distribution of the system under considering the uncertainty; the backward diagnosis reasoning of BN can recognize the weak links in system, so it is valuable for improving the system reliability.     

Fault tree analysis of feeding control system for computer numerical control heavy-duty horizontal lathes with multiple common cause failure groups

The lathes are basic machine tools for manufacturing cylindrical parts. In recent years, the DLseries computer numerical control(CNC) heavy-duty horizontal lathes(HDHLs) have been widely used in the transportation, energy and aviation industries. High availability of the CNC heavy-duty lathes is demanded to guarantee the efficiency and benefit of these manufacturing industries. As one of the key subsystems of the HDHLs, the feeding control system is studied in this paper on reliability modeling and reliability analysis. The fault tree analysis(FTA) method is used for reliability modelling of the feeding control system. Considering the multiple common cause failure groups(CCFGs) existing in the system, a modified beta factor parametric model is introduced to model the common cause failure(CCF) in system. The reliability of feeding control system is then obtained and the effect of CCF on the reliability of the whole system is studied as well.     

CAN现场总线运行故障调试和分析

CAN总线以其高可靠性、长传输距离和低成本而具有巨大的应用潜力。但在网络的构建过程中或现场调试时，可能影响网络安全运行的因素较多，使CAN总线的应用受到限制。章从网络拓扑，终端电阻的匹配、CAN波形的选择、抗干扰和接地保护等几个对网络安全运行和通信质量有严重影响的关键方面来阐述网络的维护和故障的分析诊断。     

马自达M6轿车防盗系统的检修

随着电子技术和遥控技术的不断发展,汽车防盗装置日趋严密和完善。马自达M6轿车采用了电子防盗系统,可有效地防止车辆被盗。介绍了一汽马自达M6轿车电子防盗系统的正确使用和维护方法,包括:安全灯的检查;通过专用仪器读取故障码,以确定故障发生的大致部位及原因;通过对故障码的进一步检查,以确定故障的具体部位并加以排除。     

Imprecise reliability assessment for heavy numerical control machine tools against small sample size problem

Small sample size problem is one of the main problems that heavy numerical control (NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliability data such as reliability data of similar products, expert opinion, and engineers’ experience are used in reliability assessment. However, the existing mathematical theories cannot simultaneously process the above reliability data of multiple types, and thus imprecise probability theory is introduced. Imprecise probability theory can simultaneously process multiple reliability data by quantifying multiple uncertainties (stochastic uncertainty, fuzzy uncertainty, epistemic uncertainty, etc.) together. Although imprecise probability theory has so many advantages, the existing natural extension models are complex and the computation result is imprecise. Therefore, they need some improvement for the better application of reliability engineering. This paper proposes an improved imprecise reliability assessment method by introducing empirical probability distributions to natural extension model, and the improved natural extension model is applied to the reliability assessment of heavy NC machine tool spindle to illustrate its effectiveness.     

电子雕刻机及其微机控制系统

电子雕刻机计算机控制系统的设计与实现是一个涉及到光、机、电、印染和印刷工艺等方面的复尔技术问题,本文对我国研制的第一台配有微机控制系统的 DDJ-160型电子雕刻机的结构特点、工作方式和扫描、雕刻进给传动的微机控制系统进行了较详细的研究,给出了控制软件框图,并经反复调试证明系统工作可靠.     

TY180推土机工作装置液压系统常见故障及诊断

分析了TY180推土机工作装置液压系统的工作原理、组成结构及其典型故障,总结了常见故障的现象及其形成原因,提出了相应的排除措施;运用因果分析法、故障树分析法等故障诊断方法,绘制了推土铲刀不动或上升无力故障的鱼骨图和松土器油缸不动故障的故障树,明确了这2种故障的成因与相应结果之间的逻辑关系.实践证明:运用上述方法能够较快...     

基于PLC控制的船舶自动化系统可靠性的讨论

基于PLC控制的船舶自动化系统可靠性主要取决于PLC,通过改变PLC系统的组态可以进一步提高整个控制系统的可靠性。在基于PLC的控制系统中应用具有冗余特性的模块能大大延长系统的可靠性。实践中,美国EPD公司研制和生产的基于PLC控制的船舶自动化系统同时采用两种带有冗余I/O模块的冗余CPU系统的结合,这些船舶已经和即将投入使用,受到船东的欢迎。