Detection and isolation of actuator and sensor faults for networked control systems

Detection and isolation of actuator and sensor faults in presence of disturbance for a class of linear networked control systems is considered, while unknown network‐induced delay is taken into account. The network‐induced delay effect is modeled by time‐varying polytopic uncertainties. Using eigen‐structure assignment approach, a fault detection filter is designed to decouple the fault and plant disturbance, while minimizing the effect of the induced delays in the network, using H _∞ and H _? index theories and benefiting from the free parameters in the eigen‐structure assignment approach. If the full disturbance de‐coupling is not feasible, another filter is designed to achieve partial de‐coupling and maximum robustness against the disturbance and network‐induced delay, while sensitivity to the fault is optimized. The actuator fault and disturbance vectors are augmented to define a new disturbance vector for isolation of the sensor and actuator faults. Numerical simulations are performed to evaluate the feasibility and applicability of the proposed approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Set‐valued observer‐based active fault‐tolerant model predictive control

This paper proposes an integrated actuator and sensor active fault‐tolerant model predictive control scheme. In this scheme, fault detection is implemented by using a set‐valued observer, fault isolation (FI) is performed by set manipulations, and fault‐tolerant control is carried out through the design of a robust model predictive control law. In this paper, a set‐valued observer is used to passively complete the fault detection task, while FI is actively performed by making use of the constraint‐handling capability of robust model predictive control. The set‐valued observer is chosen to implement fault detection and isolation (FDI) because of its simple mathematical structure that is not affected by the type of faults such as sensor, actuator, and system‐structural faults. This means that only one set‐valued observer is needed to monitor all considered actuator and sensor statuses (health and fault) and to carry out the fault detection and isolation task instead of using a bank of observers (each observer matching a health/fault status). Furthermore, in the proposed scheme, the advantage of robust model predictive control is that it can effectively deal with system constraints, disturbances, and noises and allow to implement an active FI strategy, which can improve FI sensitivity when compared with the passive FI methods. Finally, a case study based on the well‐known two‐tank system is used to illustrate the effectiveness of the proposed fault‐tolerant model predictive control scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

个旧居民肺癌发病率与室内氡关系的探讨

目的 探讨云南个旧地区居民（不包括矿工和冶炼工）肺癌高发的原因。方法 应用固体核径迹探测器（简称SSNTD）方法对土壤、室内氡进行了测定。结果 发现纵贯个旧地区的个旧－小江断裂带提供了丰富的土壤氡的地下来源，在断裂带上测得土壤氡水平为世界土壤氡平均值的8．6倍，断裂带上的室内氡水平是远离断裂带室内氡水平的6．5倍。调查组室内氡平均值比对照组室内氡平均值高出44．5％。分组统计表明，室内氡水平越高，肺癌发病率（除一组例外）相应增高。结论 通过本次调查似乎可以认为肺癌发病率与室内氡水平有呈正相关的趋势。     

东芝Aquilion16 CT扫描床水平运行系统工作原理及应用

通过对东芝Aquilion16扫描床平移运动的分析,了解扫描床的结构及组成;同时,通过对扫描床水平运动过程的分析,了解伺服电路控制原理。透过扫描床工作原理的应用,介绍扫描床水平方向运动的指令、动作和反馈的控制流程,并对扫面床水平运动的故障进行分析,排查故障单元。从而累积大型医疗设备维修工作经验,增强维修工作的实用性和有效修复率,节省医疗设备维修成本。     

一种特高压直流输电线路神经网络双端故障测距新方法

提出一种基于高频量衰减特性的特高压直流输电线路神经网络双端故障测距方法。传统基于高频量衰减特性的特高压直流输电线路双端测距方法的测距精度依赖于线路衰减常数的准确求取，但准确计算线路衰减常数是一个难题。人工神经网络具有很强的非线性逼近拟合能力，利用人工神经网络方法，将不必准确计算线路衰减常数也能准确实现故障定位。选取不同频带内整流侧和逆变侧测距装置处检测到的故障电压行波线模分量高频部分首波头幅值比作为BP神经网络的输入样本集，故障距离作为输出样本集，对神经网络进行训练、测试，形成直流输电线路故障测距神经网络模型，将反映故障位置的特征数据输入训练后的网络模型即可实现故障测距。大量仿真结果表明:该基于高频量衰减特性的特高压直流输电线路神经网络双端故障测距方法精度较高，而且耐受过渡电阻能力强。     

大宛齐油田薄互层油藏提高采收率对策研究

大宛齐油田属于复杂断块油藏,纵向多套油层发育,含油砂体面积小且厚度薄,注采井距仅为50~70m,油田开发过程中采用多层合采和合注的方式,层间矛盾突出。基于大量的产液剖面、吸水剖面等资料对井区层间矛盾进行系统分析,同时建立油藏数学模型,采用正交实验设计方法对含油单砂体采收率的主控因素和层间矛盾进行了系统研究,明确砂体规模、水体大小是影响砂体采收率的关键因素,基于研究成果对井区提出了砂体分类、分级动用、对应精细注水等开发调整对策并取得了良好的应用效果,对井区的下步调整和同类油田开发具有一定的指导意义。     

基于加权距离邻域选取策略的多模态过程故障检测

针对多模态过程数据密度不规则性提出的一类基于密度的方法,大多是以欧式距离为基础来比较彼此间的相似性,从而检测过程是否发生故障。然而多模态数据密度在较小范围内变化较大,采用欧式距离很难获得全面的数据信息。本文提出了一种新的基于加权距离选择邻居的策略,该策略首先对距离进行合理的加权,再根据新的加权距离重新选择样本点的邻居,能有效地避免数据信息不全面的问题。在仿真实验中,首先通过比较基于传统的欧式距离和基于本文加权距离选取的邻居,说明本文策略的优越性;进而将该策略与局部离群因子（Local Outlier Factor, LOF）结合用于TE过程,对TE过程的仿真结果表明该策略在应用于基于密度的检测方法上获得了的良好效果。     

苯泄漏事故的应急响应等级

临床技能考核是研究生中期考核的重要内容,以往的考核方法随意性和主观性较大,不能有效反应研究生的真实水平。基于SP的OSCE可以完整地模拟临床处理过程,使考核客观化、系统化、透明化,并可定量评估。我们两年来采心医学生扮演SP的OSCE组织外科临床型研究生的中期技能考核,缩短了SP的培训周期,并且SP表演的逼真性、OSCE的组织形式得到了考生和临床教师的认可,能较好地反应研究生的临床工作水平.     

双机容错技术在图书馆网络中的应用研究

 

介绍了双机容错技术的原理及其在图书馆中的应用，详细说明了双机互备援模式和双机热备份模式的双机容错模式及图书馆中常采用的系统数据镜像技术和共享磁盘技术这两种双机容错方案。