高效液相色谱仪常见故障与应对措施

高效液相色谱仪(HPLC)是药物含量及杂质分析的常用仪器,就高效液相色谱仪在使用过程中经常出现的故障及问题作了简单剖析,并提出了解决这些故障的措施。     

安捷伦高效液相色谱仪的故障诊断及仪器维护

高效液相色谱仪的故障诊断遵循一定的步骤,由于各家公司的仪器设计各不相同,步骤也有不同,下面以安捷伦1100液相色谱仪为例,将各指示灯代表的意义、故障现象,确认及排除的方法介绍如下,供维修人员在以后的故障修理中参考。     

HPLC柱的故障诊断与排除

本文介绍了高效液相色谱仪色谱柱故障的预防，诊断和排除。     

瓦里安5000型高效液相色谱仪电气故障的诊断与维修

本文通过对瓦里安５０００型高效液相色谱仪电气故障的诊断与处理，介绍了该仪器在正常使用条件下，电气故障的维修方法。     

沃特斯高效液相色谱仪51O泵控制系统

介绍了几例沃特斯高效液相色谱仪510泵电路故障及其处理方法.     

沃特斯高效液相色谱仪510泵控制系统故障分析与检修

介绍了几例沃特斯高效液相色谱仪510泵电路故障及其处理方法。     

Waters高效液相色谱仪柱温箱故障分析与维修1例

温控系统由温控器及柱温箱组成,是Waters高效液相色谱仪重要的组成部件.在设定温度下,温控系统可以避免柱温受外界的影响,从而保持柱温恒定对保证分析结果的重复性、准确性有非常重要的作用.通过对柱.温箱故障现象及其控制电路的分析,确定故障原因为固态继电器损坏,更换相应继电器,故障消除.     

岛津 LC- 4A型高压液相色谱仪 PC- 2H主板故障的检修

介绍了岛津LC-4A型高效液相色谱仪PC-2H主板故障的检修。提出了维修和使用时应注意的问题。     

高效液相色谱仪常用检测器的使用与维护

高效液相色谱是高等院校、药业、食品、环保等各个领域常用的仪器之一。笔者对常用检测器的故障进行分析、同时对示差折光检测器的原理及使用等进行介绍,旨在给从事液相色谱仪使用的人员提供一点参考。     

UV100／200型紫外检测器计算机控制系统故障分析与排除

紫外检测器是液相色谱仪常用的检测器,出现故障会直接影响谱仪的使用。美国瓦里安公司生产的UV100和UV200型紫外检测器设计先进,自动化程度很高,分别配置在该公司VISTA5000型和VISTA5500型液相色谱仪上。作者在工作中发现,这两种检测器的故障大多发生在单板计算机控制电路中。以下是几个故障实例。     

液压马达的状态监测及故障诊断方法的研究

利用神经网络方法解决液压马达多故障诊断的问题。文中通过对液压马达故障机理的分析，针对液压马达多故障模式提出了利用神经网络进行多故障诊断的策略。理论和试验结果分析表明，利用神经网络方法可以有效地诊断和识别液压马达多故障模式，其识别率随着学习样本量的增大而提高。     

Bayesian networks: application in safety instrumentation and risk reduction

The Safety Integrity Level (SIL) of a Safety Instrumented Function (SIF) depends on failures of the various components involved in performing the function. These failures depend on various factors and can be random hardware failures and/or systematic failures. Failure of a SIF need not necessarily result in a hazardous event when there are other layers of protection. Hence the residual risk probability that is left out after various layers of protection is of interest and it should be tolerable. In order to find the residual risk due to a hazard we need to know the demand rate of the hazard, the failure rates of various layers of protection and the factors which influence these failures. So the failure rates are not static and are dynamic, as various factors come into play during the lifecycle of the protection devices involved. In this paper the author proposes Bayesian belief networks to build the scenario based hazard probability model and uses that in the post-design phase to track the residual risk probability. An example is used to illustrate the application.     

An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs

This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, mitigating the IGBTs failures by specific inverter control. Indeed, the two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number).     

功能危险分析在飞机刹车系统中的应用研究

功能危险分析(Functional Hazard Analysis,即FHA)是一个分析和评估过程,主要是以分析评估系统内或设备中潜在的故障及所发生故障的影响。它通过分析来确定系统操作中可能发生的故障,并判断故障对人员的危害。FHA是系统安全评估中的重要内容,是其他安全性分析项目的基础,更是民用飞机满足适航审定要求必须完成的分析项目。通过对功能危险分析方法在飞机刹车系统应用过程的分析,总结了该方法应用时遇到的难点以及应对办法,并简要说明了分析结果。     

具有随机机器故障的制造过程建模与性能分析

为研究机器故障和维修活动对制造过程性能的影响,提出一种基于广义随机Petri网的制造过程建模与性能分析方法.分析了随机机器故障特征;定义了两种故障发现模式和两种中断作业处理策略;给出具有随机机器故障的制造过程的不同模型方法;通过对模型结构特征的分析,证明了其有效性.针对不同策略和参数设置进行了性能仿真.分别以平均产量和平均过程流时间等性能指标,分析了单个工作站的性能;采用平均产量,分析了具有两个工作站的流水线的性能.仿真结果表明,故障率、平均维修时间、缓存数量配置、维修工人数量、故障发现模式和中断作业处理策略是影响具有随机机器故障的制造过程性能的主要因素.     

Condition monitoring of planetary gearbox by hardware implementation of artificial neural networks

The hazards of planetary gearboxes’ failures are the most crucial in the machinery which directly influence human safety like aircrafts. But also in an industry their damages can cause the large economic losses. Planetary gearboxes are used in wind turbines which operate in non-stationary conditions and are exposed to extreme events. Also bucket-wheel excavators are equipped with high-power gearboxes that are exposed to shocks. Continuous monitoring of their condition is crucial in view of early failures, and to ensure safety of exploitation. Artificial neural networks allow for a quick and effective association of the symptoms with the condition of the machine. Extensive research shows that neural networks can be successfully used to recognize gearboxes’ failures; they allow for detection of new failures which were not known at the time of training and can be applied for identification of failures in variable-speed applications. In a majority of the studies conducted so far neural networks were implemented in the software, but for dedicated engineering applications the hardware implementation is being used increasingly, due to high efficiency, flexibility and resistant to harsh environmental conditions. In this paper, a hardware implementation of an artificial neural network designed for condition monitoring of a planetary gearbox is presented. The implementation was done on a Field Programmable Gate Array (FPGA). It is characterized by much higher efficiency and stability than the software one. To assess condition of a gearbox working in non-stationary conditions and for chosen failure modes, a signal pre-processing algorithm based on filtration and estimation of statistics from the vibration signal was used. Additionally, the rewards-punishments training process was improved for a selected neural network, which is based on a Learning Vector Quantization (LVQ) algorithm. Presented classifier can be used as an independent diagnostic system or can be combined with traditional data acquisition systems using FPGAs.     

浅谈液压系统故障的诊断方法与步骤

筒述液压系统故障的分类及可能引起液压系统故障的原因和如何快速准确对液压故障进行诊断的方法与步骤,并通过对油压机故障的诊断和分析来说明如何快速准确诊断液压系统故障。     

The auto-diagnosis system of an intelligent measuring instrument

The methodological aspects and the design of the automatic self-diagnosis (auto-diagnosis) system of a high-performance measuring instrument for electrical quantities are described. The auto-diagnosis system can recognise not only severe failures which require out-of-service instrument setting, but also slight failures simply affecting accuracy or not basic features; in the latter case, the instrument is set working in degraded conditions. The auto-diagnosis process is performed making reference to the instrument architecture, based on independent and interconnected functional units, and using an analysis technique, called ‘extending ring’, to detect failing subsystems.The auto-diagnosis system is divided into two main parts, conceived for separate aims: one is named ‘off-line full test auto-diagnosis system’ and performs, at power up or on user request, a full comprehensive test; the other, named ‘on-line auto-diagnosis system’, continuously monitors the instrument behaviour while operating normally to reveal failures or error conditions that can derate the whole performance.     

一种改进的时滞不确定性系统鲁棒容错控制算法

研究了一类具有时滞不确定性系统的鲁棒容错控制问题,针对既有传感器失效,又有执行器失效的故障情形,通过引入一种无记忆的状态反馈控制器,基于Lyapunov稳定定理和运用线性矩阵不等式(LMI)的方法,给出了在传感器失效和执行器失效故障下具有鲁棒完整性的充分条件,并进行了证明。最后利用Matlab中的LMI工具箱进行了算例仿真,证实了这种设计方法的有效性和可行性,减少了当出现故障时需要先判断哪类故障的任务,为容错控制提供了便利。