限定记忆模式的MEWMA-ICA方法研究及其应用

传统基于多变量指数移动加权平均的独立元分析(MEWMA-ICA)方法:虽然可以有效监测化工过程中的缓变故障,但对突变故障监测滞后。本文提出了限定记忆模式的MEWMA-ICA方法:。该方法:通过引入基于记忆代数的遗忘因子,构造动态建模数据集。随后利用动态数据集建立ICA统计分析模型。最后采用T~2和SPE统计量对系统进行监测。其中,遗忘因子和记忆代数是通过优化算法进行选择的。通过测试问题和裂解气压缩机的仿真研究,验证了限定记忆模式的MEWMA-ICA方法:在保证传统MEWMA-ICA算法对缓变故障监测能力的同时,减少了对突变故障监测的时滞。     

化工过程故障原因诊断的变量异常顺序法

为对化工过程故障进行实时诊断,建立设了备的主元分析(Principal component analysis,PCA)模型,根据实时数据和PCA模型计算综合指标以在线检测其故障的发生,并提出了PCA模型的在线更新策略,以适应实际过程中工况缓变特性。为在线监测到故障发生时,能确定故障根原因,根据各变量的DCS报警上下限判断其异常状态,并记录各变量出现异常的时间顺序,以供操作人员参考,从而准确地诊断所发生故障的根源。基于过程安全生产指导平台,将所提出的方法实际应用于某炼油厂延迟焦化装置的分馏塔单元,长期在线应用结果表明所提出的在线更新PCA模型能准确地连续检测出故障的发生并适应工况的缓变,而变量异常顺序可帮助操作人员正确地确定故障原因。     

双余度传感器缓变故障检测的改进残差检验法

分析了基于卡尔曼滤波器的残差检验法对传感器缓变故障检测的不敏感性原因.针对双余度传感器缓变故障检测,采取了先故障判断后故障定位的故障检测策略,并提出了一种基于移动伪正常状态的残差构造方法.数学仿真验证了改进方法比传统方法更能够及时准确地识别双余度传感器缓变故障.     

基于MEWMA PCA的微小故障检测方法研究及其应用

针对过程中难以检测到的微小、缓变故障的检测问题，提出一种新的多变量统计过程监测方法，把传统的单变量EWMA扩展为多变量EWMA，并与PCA方法相结合，构成新的MEWMA-PCA方法，重新构造统计量 和 并建立其对应的统计限，详细分析了各个统计量的统计性能指标及其影响因素。通过对Tennessee Eastman（TE）过程的仿真研究，说明提出的方法是可行的，并有效地改进了该过程微小故障的检测效果，从而更好地保证了过程运行的安全、稳定性。     

基于PCA与KPCA的TE过程故障检测应用研究

针对传统主元分析法(PCA)应用于复杂非线性的化工过程故障检测时存在性能差的问题,提出利用核主元分析法(KPCA)来进行故障检测的思想.从而将输入空间中复杂的非线性问题转化为特征空间中的线性问题.将上述方法应用于Tennessee Eastman(TE)化工过程模型,仿真结果表明,KPCA方法在复杂非线性化工过程敝障检测方面的应用明显优于普通的PCA方法.     

TE过程微小故障的多变量统计方法

针对化工过程中发生的微小故障问题,将传统的单变量方法转换成多变量,即多变量累计和(Multivariate Cumulative Sum MCUSUM)和多变量指数加权移动平均(Multivariate Exponent Weighted Moving MEWMA)的混合方法,并利用传统的独立元分析法提取独立元进行降维,最后利用支持向量机数据描述建立统计量及控制限。通过对Tennessee Eastman(TE)过程的仿真研究,验证了该方法的可行性和有效性,改善了该过程微小故障的检测效果,从而更好地保证过程运行的安全、稳定性。     

BP神经网络辅助的缓变故障双阈值检测法

针对传统$\chi ^2$检测法对惯性/卫星组合导航缓变故障检测效率不高的问题,提出一种基于BP神经网络辅助的缓变故障双阈值检测法.基于BP神经网络建立位置与速度子预测器,实现对卫星导航量测数据的预测,在此基础上根据预测精度提出双阈值的低检测门限,辅助残差chi^2检测法进行故障检测与系统重构.仿真结果表明,对于缓变故障,所提出方法能有效提高故障期间滤波精度、降低漏警率以及组合导航的可靠性.     

基于PCA与OLPP混合方法的化工过程故障检测

对于复杂的工业过程,采集到的过程数据能反映出生产过程的内在变化和运行状况。本文提出一种新的多变量统计过程监测策略,数据建模过程包含主元分析(Principal Component Aanlysis,PCA)与正交局部保持投影(Orthogonal Locality PreservingProjection,OLPP)两步。首先利用PCA在不丢失任何信息的前提下将原始数据旋转成不相关的潜变量,然后再作OLPP以提取能表征过程正常数据内在局部近邻结构的特征用于故障检测。利用T~2和SPE(或Q)统计量以及核密度估计方法确定的控制限进行化工过程的在线监测,TE过程仿真实验验证了该混合方法的有效性和优越性。     

基于多尺度核主元分析的非线性过程监控方法研究

针对化工过程数据的多尺度性和非线性特性,提出了一种多尺度核主元分析方法(MSKPCA)监控过程的运行状态。使用小波变换在不同尺度下分解测量信号．然后借助于核函数对分解后的数据进行非线性变换,在变换后的线性空间中用主元分析(PCA)提取过程数据的主要特征,构造监控统计量T2和Q来检测故障。在此基础上,提出了一种贡献图方法．计算过程变量对故障的贡献量,用于故障变量的分离。在TE过程上的监控结果表明,MSKPCA可以比PCA和动态PCA更迅速地检测到过程故障,贡献图方法能够正确地分离故障变量。     

基于差分分段PCA的多模态过程故障监测

多模态的故障监测是一个复杂的问题, 既需要考虑稳定模态下的故障监测, 也需要考虑不同模态间的过渡故障监测. 不同稳定模态下的数据具有不同的相关关系, 对每个稳定模态需要建立不同的稳定模态模型. 当稳定生产模态发生改变时, 生产过程进入过渡模态, 需要考虑过渡变量相关关系的变化. 本文通过对过渡数据差分, 得到变量相对变化信息. 利用主成分分析(Principal component analysis, PCA)分段对差分变量的相关特性进行分析, 提取相对变化的特征. 最后以实际连续退火机组生产线为背景, 用基于差分分段PCA的多模态方法对多模态过程进行故障监测, 发现算法很好地反映了实际过渡过程机理, 验证了算法的有效性.     

Improving facility planning with decision technology systems

Facility planning is a complex process that requires art, science, and technology. Several methodologies have been generated to facilitate this process. Computer information systems (CIS) have been developed to deliver these methodologies and to provide knowledge relevant for effective facility planning. Since accurate decisions are required at each step of the process, the development effort has focused on CISs that support decision-making.Traditionally, the support has been provided in a segmented fashion and for separate phases of the decision-making process. To be absolutely effective, the support should be integrated and complete. There have been efforts to provide the required CIS support, but these systems have inherent conceptual shortcomings. Moreover, the newer and enhanced systems create additional problems that will prevent them from providing integrated support for all decision making phases in facility planning.This paper examines the facility planning process. Then traditional and enhanced information systems support is reviewed and the inherent shortcomings and unresolved integration problems are explained. Finally, an alternative approach, referred to as a Decision Technology System (DTS), is proposed to resolve the difficulties.     

A simulation sequencing algorithm

In the course of developing a programming project for a course in operating systems, a general purpose language (Burroughs B6700 Algol) possessing concurrency and semaphores was used to provide a process oriented simulation sequencing facility. This facility has been used successfully to simulate several simple operating systems. The facility comprises three procedures along with ‘simulation semaphore’ variables. The first procedure, when called, inserts a simulated time delay into the progress of a simulation model process: the latter two procedures provide a P and a V operation on simulation semaphores, and are used to synchronize processes in a simulation model. The P operation may insert a simulated time delay into the progress of a process. These procedures are explained and presented along with a simple example to show their use.     

基于CORBA的TE过程仿真器实现

TE过程(Tennessee Eastman process)是对一个化工过程的真实模拟，它被广泛用于过程控制研究。它的设计目的采对基于Eastman Chemical的化工过程的各种故障的模拟。然而，原有的用Fortran写成的模拟器不利于与其他应用、软件的数据共享。该文用C Builder重新编写了TE过程仿真器，使用CORBA技术实现数据共享。仿真器界面友好、功能齐全，为研究过程工程任务的人员提供良好的基础平台。     

Computer aided control system design applied to milk drying plants

This paper reviews a computer aided control system design facility that has been used to develop a set of control systems that have been implemented on a pilot scale industrial process. The facility caters for a broad range of control situations including those with interactions, time delays and disturbances. Online interactive graphics is used as a design aid for the identification of plant dynamics and for the assessment of control system performance. Control systems may be developed systematically to be structured in a hierarchical configuration on the plant. Particular applications to the plant, an evaporator and a spray drier, are discussed in detail.     

BIM-enabled facilities operation and maintenance: A review

Building Information modeling (BIM) has the potential to advance and transform facilities Operation and Maintenance (O&M) by providing a platform for facility managers to retrieve, analyze, and process building information in a digitalized 3D environment. Currently, because of rapid developments in BIM, researchers and industry professionals need a state-of-the-art overview of BIM implementation and research in facility O&M. This paper presents a review of recent publications on the topic. It aims to evaluate and summarize the current BIM-O&M research and application developments from a facility manager's point of view, analyze research trends, and identify research gaps and promising future research directions. The scope of this research includes the academic articles, industry reports and guidelines pertaining to using BIM to improve selected facility O&M activities, including maintenance and repair, emergency management, energy management, change/relocation management, and security. The content analysis results show that research on BIM for O&M is still in its early stage and most of the current research has focused on energy management. We have identified that the interoperability in the BIM-O&M context is still a challenge and adopting the National Institute of Standards and Technology (NIST) Cyber-Physical Systems (CPS) Framework is a potential starting point to address this issue. More studies involving surveys are needed to understand the underlying O&M principles for BIM implementation – data requirements, areas of inefficiencies, the process changes. In addition, more studies on the return on investment of the innovative systems are required to justify the value of BIM-O&M applications and an improved Life Cycle Cost Analysis method is critical for such justifications.     

System lifecycle processes for cyber security in a research reactor facility

The digitalization of nuclear facilities has brought many benefits,including high performance and convenient maintainability,in terms of facility operation.However,cyber accidents accompanied by the use of digital technologies have increased,and cyber security has been one of the most important issues in the nuclear industry area.Several guidelines have been published for nuclear power plants,but it is difficult to apply all requirements within the guidelines to research reactor facilities because the characteristics in terms of facility scale,purpose,and system design,are different from those of power plants.To address this emerging topic,this paper introduces system lifecycle processes for cyber security in a research reactor facility.It addresses the integration of activities for securing systems and guarding a facility safely using the practices at a research reactor facility.     

Correlations between characteristics of maximum influence and degree distributions in software networks

Software systems can be represented as complex networks and their artificial nature can be investigated with approaches developed in network analysis.Influence maximization has been successfully applied on software networks to identify the important nodes that have the maximum influence on the other parts.However,research is open to study the effects of network fabric on the influence behavior of the highly influential nodes.In this paper,we construct class dependence graph(CDG)networks based on eight practical Java software systems,and apply the procedure of influence maximization to study empirically the correlations between the characteristics of maximum influence and the degree distributions in the software networks.We demonstrate that the artificial nature of CDG networks is reflected partly from the scale free behavior:the in-degree distribution follows power law,and the out-degree distribution is lognormal.For the influence behavior,the expected influence spread of the maximum influence set identified by the greedy method correlates significantly with the degree distributions.In addition,the identified influence set contains influential classes that are complex in both the number of methods and the lines of code(LOC).For the applications in software engineering,the results provide possibilities of new approaches in designing optimization procedures of software systems.     

Assessment of gradient-based iterative learning controllers using a multivariable test facility with varying interaction

A multiple input, multiple output (MIMO) experimental test facility has been developed for the evaluation, benchmarking and comparison of iterative learning control (ILC) strategies. The system addresses the distinct lack of experimental studies for the multivariable case and enables controller performance and robustness to be rigorously investigated over a broad range of operating conditions. The electromechanical facility is multi-configurable with up to 3 inputs and permits both exogenous disturbance injection and a variable level of coupling to be applied between input and output pairs. To confirm its suitability for evaluation and comparison of ILC, theoretical results are derived for two popular forms of gradient-type ILC algorithm, linking interaction with fundamental performance limitations. The test facility is then used to establish how well theoretical predictions match experimental results. The analysis is then extended to provide solutions to address this performance degradation, and these are again confirmed using the test facility.     

Quantitative knowledge based approach for preliminary design of tall buildings

A knowledge based expert system for the preliminary design of tall buildings has been developed. The system implementation is based on the integration of symbolic and numerical processing. A domain independent shell has been employed in the expert system development and verification. The rule based knowledge base of the system includes a set of IF/THEN rules that provide the inference mechanism with the information needed in the judgemental process. A numerical algorithm is introduced to help quantify the decision making process by relating the confidence factors for each possible solution to a numerical quantity defined as the virtual number of stories. The judgemental process is coupled with the numerical algorithm through the external program facility provided in the expert system development shell.